Publications

2026

1. OE

   InGaAs membrane plasmonic photodetector with Ni-InGaAs alloy integrated on Si waveguide

   Kentaro Komatsu, Taketoshi Nakayama, Tomohiro Akazawa, and 10 more authors

   Opt. Express, Feb 2026

   Abs DOI Bib

   

   We propose III-V/Si hybrid plasmonic waveguide photodetector incorporating an InGaAs membrane. We confirmed that Ni-InGaAs alloy functions effectively as an electrode for a plasmonic waveguide. Utilizing Ni-InGaAs alloy enabled the integration of plasmonic waveguide photodetectors into the Si photonics platform through a simplified fabrication process. We achieved a responsivity of 0.13 A/W at 1 V with a dark current of 400 nA and confirmed a 32.1 Gbit/s clear eye diagram, demonstrating the potential for high speed InGaAs plasmonic photodetector in Si photonics.

   @article{KOMATSU_2026_OE,
     author = {Komatsu, Kentaro and Nakayama, Taketoshi and Akazawa, Tomohiro and Wakita, Yosuke and Sakumoto, Hiroya and Zhang, Chao and Miyatake, Yuto and Monfray, St\'{e}phane and Boeuf, Fr\'{e}d\'{e}ric and Tang, Rui and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Opt. Express},
     keywords = {Numerical simulation; Optical interconnects; Optical modulators; Plasmon waveguides; Scanning electron microscopy; Waveguide cores},
     number = {3},
     pages = {3932--3940},
     publisher = {Optica Publishing Group},
     title = {InGaAs membrane plasmonic photodetector with Ni-InGaAs alloy integrated on Si waveguide},
     volume = {34},
     month = feb,
     year = {2026},
     url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-34-3-3932},
     doi = {10.1364/OE.586807},
   }

2. JSAP

   [第47回論文奨励賞受賞記念講演] 進化戦略を用いた小型・低損失・広帯域2×2シリコン光カプラの設計と実証

   宮武悠人, トープラサートポンカシディット, 高木信一, and 1 more author

   In 第73回応用物理学会春季学術講演会, Mar 2026

   Abs Bib

   我々はCMA-ESと呼ばれる進化戦略アルゴリズムを用いた設計手法を提案し、これまでに様々なシリコンフォトニクス受動素子の設計に適用してきた。今回、2×2シリコン光カプラの設計に取り組み、小型・低損失・広帯域のデバイスを実験的に実証した。実証した2×2シリコン光カプラは、マッハ・ツェンダー型光回路の大規模化とハードウェアエラーの低減に貢献する。

   @inproceedings{MIYATAKE_2026_JSAP-SPRING,
     author = {宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {第73回応用物理学会春季学術講演会},
     title = {[第47回論文奨励賞受賞記念講演] 進化戦略を用いた小型・低損失・広帯域2×2シリコン光カプラの設計と実証},
     year = {2026},
     volume = {},
     number = {17p-WL2_401-1},
     pages = {},
     month = mar,
   }

3. JSAP

   Ge₂Sb₂Te₃S₂光強度変調器を用いた低クロストーク1×2シリコンMZI光スイッチ

   小林研二, 宮武悠人, 唐睿, and 6 more authors

   In 第73回応用物理学会春季学術講演会, Mar 2026

   Abs Bib

   人工知能（AI）の発展に伴い、シリコンフォトニクスを用いたプログラマブル光集積回路（PIC）が注目されている。本研究では、マイクロリング共振器（MRR）にワイドギャップ相変化材料Ge2Sb2Te3S3（GSTS）を光強度変調器として用いることで、低損失かつ広帯域の不揮発性光スイッチを実現した。

   @inproceedings{KOBAYASHI_2026_JSAP-SPRING,
     author = {小林研二 and 宮武悠人 and 唐睿 and 牧野孝太郎 and 畑山, 祥吾 and 岡野誠 and トープラサートポン, カシディット and 高木信一 and 竹中充},
     booktitle = {第73回応用物理学会春季学術講演会},
     title = {Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>光強度変調器を用いた低クロストーク1×2シリコンMZI光スイッチ},
     year = {2026},
     volume = {},
     number = {18a-WL2_401-5},
     pages = {},
     month = mar,
   }

4. IEICE

   シリコンフォトニクスを用いた光AI演算回路

   唐睿, 柴成立, 大野修平, and 11 more authors

   In 2026年電子情報通信学会総合大会, Mar 2026

   Bib

   @inproceedings{TANG_2026_IEICE-SPRING,
     author = {唐睿 and 柴成立 and 大野修平 and 張超 and 宮武悠人 and 谷澤健 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 池田和浩 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {2026年電子情報通信学会総合大会},
     title = {シリコンフォトニクスを用いた光AI演算回路},
     year = {2026},
     volume = {},
     number = {CI-4},
     pages = {},
     month = mar,
   }

5. BOOK

   

   シリコンフォトニクスによる光デバイスの開発と異種材料集積化 第2章 第7節 相変化材料を用いた低損失光位相変調器の研究開発

   宮武悠人

   2026

   HTML

2025

1. OME

   

   Low-loss Sb₂S₃ optical phase shifter enabled by optimizing sputtering conditions

   Yuto Miyatake, Tomohiro Anda, Yosuke Wakita, and 6 more authors

   Opt. Mater. Express, Aug 2025

   Abs DOI Bib

   

   By quantitatively evaluating the atomic concentrations of sputtered Sb₂S₃ films with different sputtering powers and Ar flows, we reveal that a sputtered Sb₂S₃ film becomes close to the stoichiometric composition as the sputtering power and Ar flow decrease. We characterize the optical properties of Sb₂S₃ and show that the lower sputtering power leads to a better figure of merit of Sb₂S₃ as an optical phase shifter in the near infrared (NIR) range. Based on these results, we achieve a loss per phase shift of 0.33 dB/\pi at a wavelength of 1.55 \mum, one of the lowest losses among Sb₂S₃ phase shifters in the NIR range.

   @article{MIYATAKE_2025_OME,
     author = {Miyatake, Yuto and Anda, Tomohiro and Wakita, Yosuke and Makino, Kotaro and Hatayama, Shogo and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Opt. Mater. Express},
     keywords = {Extinction coefficients; Near infrared; Optical absorption; Optical computing; Optical properties; Phase shift},
     number = {8},
     pages = {1972--1986},
     publisher = {Optica Publishing Group},
     title = {Low-loss Sb<sub>2</sub>S<sub>3</sub> optical phase shifter enabled by optimizing sputtering conditions},
     volume = {15},
     month = aug,
     year = {2025},
     url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-15-8-1972},
     doi = {10.1364/OME.568607},
   }

2. IPC

   Direct Laser Lithography on Sb₂S₃ Thin Film for Optical Waveguide Fabrication

   Mamoru Tanabe, Jooyoung Yoo, Kotaro Makino, and 5 more authors

   In 2025 IEEE Photonics Conference (IPC), Nov 2025

   Abs DOI Bib

   

   We successfully fabricated rewritable photonic devices by inducing amorphization in Sb₂S₃ thin films using direct laser lithography. Line/space patterning with a 500 nm pitch was achieved, enabling the successful demonstration of grating couplers and single-mode waveguides.

   @inproceedings{TANABE_2025_IPC,
     author = {Tanabe, Mamoru and Yoo, Jooyoung and Makino, Kotaro and Hatayama, Shogo and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {2025 IEEE Photonics Conference (IPC)},
     title = {Direct Laser Lithography on Sb<sub>2</sub>S<sub>3</sub> Thin Film for Optical Waveguide Fabrication},
     year = {2025},
     volume = {},
     number = {},
     pages = {1-2},
     keywords = {Optical device fabrication;Lithography;Waveguide lasers;Couplers;Optical coupling;Optical sensors;Optical films;Gratings;Optical waveguides;Photonics;phase change material;optical waveguides;grating coupler;laser direct lithography;photonic integrated circuit},
     doi = {10.1109/IPC65510.2025.11282352},
     issn = {2575-274X},
     month = nov,
   }

3. ECOC

   Phase-Error-Correctable 4×4 Programmable Photonic Integrated Circuit Enabled by Dual-Functional Si PIN Waveguides as Phase Shifter and Transparent Power Monitor

   Tomohiro Akazawa, Rui Tang, Yuto Miyatake, and 4 more authors

   In 2025 European Conference on Optical Communications (ECOC), Sep 2025

   Abs DOI Bib

   

   We experimentally demonstrate the phase error correction of a 4 \times 4 programmable PIC using Si PIN waveguides which function as phase shifter and transparent in-line power monitor. Employing dual-functional PIN waveguides enables a simple, fast, and error-correctable programmable PIC with the minimal number of devices.

   @inproceedings{AKAZAWA_2025_ECOC,
     author = {Akazawa, Tomohiro and Tang, Rui and Miyatake, Yuto and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {2025 European Conference on Optical Communications (ECOC)},
     title = {Phase-Error-Correctable 4×4 Programmable Photonic Integrated Circuit Enabled by Dual-Functional Si PIN Waveguides as Phase Shifter and Transparent Power Monitor},
     year = {2025},
     volume = {},
     number = {},
     pages = {1-4},
     keywords = {Transmission line matrix methods;Phase shifters;Photonic integrated circuits;Europe;Silicon;Optical fiber communication;Pins;Error correction;Optical waveguides;Monitoring},
     doi = {10.1109/ECOC66593.2025.11263031},
     issn = {},
     month = sep,
   }

4. OECC/PSC

   Non-Volatile Optical Phase Shifters for Photonic Computing

   Mitsuru Takenaka, Rui Tang, Yuto Miyatake, and 10 more authors

   In 2025 30th OptoElectronics and Communications Conference (OECC) and 2025 International Conference on Photonics in Switching and Computing (PSC), Jun 2025

   Abs DOI Bib

   

   We demonstrated non-volatile optical phase shifters using III-V/Si MOSCAPs with FeFETs, phase change material GSTS at mid-infrared wavelength, and ferroelectric \textHfZrO_2 for energy-efficient photonic computing.

   @inproceedings{TAKENAKA_2025_OECC_PSC,
     author = {Takenaka, Mitsuru and Tang, Rui and Miyatake, Yuto and Akazawa, Tomohiro and Sakumoto, Hiroya and Wakita, Yosuke and Bhardwaj, Dhruv Ishan and Kobayashi, Kenji and Makino, Kotaro and Hatayama, Shogo and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {2025 30th OptoElectronics and Communications Conference (OECC) and 2025 International Conference on Photonics in Switching and Computing (PSC)},
     title = {Non-Volatile Optical Phase Shifters for Photonic Computing},
     year = {2025},
     volume = {},
     number = {invited},
     pages = {1-2},
     keywords = {Phase change materials;Optical polarization;Ferroelectric materials;Optical device fabrication;Phase shifters;Optical materials;Optical modulation;Optical waveguides;FeFETs;Photonics},
     doi = {10.23919/OECC/PSC62146.2025.11109756},
     issn = {2166-8892},
     month = jun,
   }

5. CLEO

   Heterogeneous Integration for Programmable Photonic Integrated Circuits

   Mitsuru Takenaka, Rui Tang, Yuto Miyatake, and 15 more authors

   In 2025 Conference on Lasers and Electro-Optics (CLEO), May 2025

   Abs DOI Bib

   

   Heterogeneous material integration is essential for Si photonics for advanced performance and functionalities. In this paper, we discuss how III-V semiconductors, phase change materials, and ferroelectrics contribute to Si programmable photonic integrated circuits. © 2025 The Author(s)

   @inproceedings{TAKENAKA_2025_CLEO,
     author = {Takenaka, Mitsuru and Tang, Rui and Miyatake, Yuto and Chai, Chengli and Akazawa, Tomohiro and Sakumoto, Hiroya and Wakita, Yosuke and Bhardwaj, Dhruv Ishan and Komatsu, Kentaro and Kobayashi, Kenji and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Monfray, Stéphane and Boeuf, Frédéric and Toprasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {2025 Conference on Lasers and Electro-Optics (CLEO)},
     title = {Heterogeneous Integration for Programmable Photonic Integrated Circuits},
     year = {2025},
     volume = {},
     number = {},
     pages = {1-2},
     keywords = {Phase change materials;Semiconductor lasers;Photonic integrated circuits;Multichip modules;Silicon;Laser transitions;III-V semiconductor materials;Electro-optical waveguides;Photonics},
     doi = {},
     issn = {2160-8989},
     month = may,
   }

6. CLEO

   Non-volatile Si microring resonator switch with Ge₂Sb₂Te₃S₂ optical intensity modulator

   Kenji Kobayashi, Yuto Miyatake, Rui Tang, and 7 more authors

   In 2025 IEEE Silicon Photonics Conference (SiPhotonics), Apr 2025

   Abs DOI Bib

   

   We demonstrate microring resonator (MRR) optical switch using phase change material Ge2Sb2Te3Se2 (GSTS). With negligible optical absorption in amorphous GSTS, the MRR maintains its Q-factor after GSTS integration. Successful non-volatile switching is achieved over broad wavelength range with crystalline GSTS, enabling multi-wavelength programmable photonic circuits.

   @inproceedings{KOBAYASHI_2025_CLEO,
     author = {Kobayashi, Kenji and Miyatake, Yuto and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {2025 IEEE Silicon Photonics Conference (SiPhotonics)},
     title = {Non-volatile Si microring resonator switch with Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> optical intensity modulator},
     year = {2025},
     volume = {},
     number = {},
     pages = {1-2},
     keywords = {Q-factor;Phase change materials;Absorption;Optical switches;Optical resonators;Optical computing;Optical fiber networks;Silicon photonics;Optical materials;Switching circuits;Phase-change material;microring resonator;intensity modulation;optical switching},
     doi = {10.1109/SiPhotonics64386.2025.10985637},
     issn = {1949-209X},
     month = apr,
   }

7. PCSI

   Non-volatile optical phase shifters on Si photonics platform

   Mitsuru Takenaka, Yuto Miyatake, Kazuma Tang, and 13 more authors

   In 50th Conference on the Physics and Chemistry of Surfaces and Interfaces (PCSI-50), Jan 2025

   Bib

   @inproceedings{TAKENAKA_2025_PCSI,
     author = {Takenaka, Mitsuru and Miyatake, Yuto and Tang, Rui Taki, Kazuma and Sekine, Naoki and Watanabe, Kohei and Akazawa, Tomohiro and Sakumoto, Hiroya and and Bhardwaj, Dhruv Ishan and Fujita, Masahiro and Tang, Hanzhi and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {50th Conference on the Physics and Chemistry of Surfaces and Interfaces (PCSI-50)},
     title = {Non-volatile optical phase shifters on Si photonics platform},
     year = {2025},
     volume = {},
     number = {MoM2-33, invited},
     month = jan,
   }

8. JSAP

   標準シリコンフォトニクスにおけるMOSFETの短チャネル効果抑制のための設計

   宮武悠人, 池田誠, and 竹中充

   In 第72回応用物理学会春季学術講演会, Mar 2025

   Abs Bib

   標準的なシリコンフォトニクスプロセスの設計ルール内で、SOI層の側壁にチャネルをもつサイドゲートMOSFETの設計を改善し、短チャネル効果の抑制を図った。シミュレーションによる解析に基づいて、ソース・ドレインの浅接合化、チャネル直下の基板ドーピングの導入、ゲートドーピングの極性の反転により短チャネル効果の抑制と閾値電圧の低減に成功し、チャネル長を短縮することで駆動力の改善に成功した。

   @inproceedings{MIYATAKE_2025_JSAP-SPRING,
     author = {宮武悠人 and 池田誠 and 竹中充},
     booktitle = {第72回応用物理学会春季学術講演会},
     title = {標準シリコンフォトニクスにおけるMOSFETの短チャネル効果抑制のための設計},
     year = {2025},
     volume = {},
     number = {17a-K305-6},
     pages = {},
     month = mar,
   }

9. JSAP

   光パワーモニタ内蔵Si PIN型位相シフタを用いた4×4プログラマブル光回路における位相誤差補正の実証

   赤澤智熙, 唐睿, 宮武悠人, and 4 more authors

   In 第86回応用物理学会秋季学術講演会, Sep 2025

   Bib

   @inproceedings{AKAZAWA_2025_JSAP-AUTUMN,
     author = {赤澤智熙 and 唐睿 and 宮武悠人 and 岡野誠 and トープラサートポン, カシディット and 高木信一 and 竹中充},
     booktitle = {第86回応用物理学会秋季学術講演会},
     title = {光パワーモニタ内蔵Si PIN型位相シフタを用いた4×4プログラマブル光回路における位相誤差補正の実証},
     year = {2025},
     volume = {},
     number = {9p-N202-9},
     pages = {},
     month = sep,
   }

10. JSAP

    Ge₂Sb₂Te₃S₂光強度変調器を用いた低クロストーク1×2シリコンMZI光スイッチ

    小林研二, 宮武悠人, 唐睿, and 7 more authors

    In 第72回応用物理学会春季学術講演会, Mar 2025

    Bib

    @inproceedings{KOBAYASHI_2025_JSAP-SPRING,
      author = {小林研二 and 宮武悠人 and 唐睿 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第72回応用物理学会春季学術講演会},
      title = {Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>光強度変調器を用いた低クロストーク1×2シリコンMZI光スイッチ},
      year = {2025},
      volume = {},
      number = {16ppK305-4},
      pages = {},
      month = mar,
    }

11. JSAP

    III-V/Siハイブリッド導波路向けSb₂S₃不揮発光位相シフタの検証

    脇田耀介, 宮武悠人, 大野修平, and 8 more authors

    In 第72回応用物理学会春季学術講演会, Mar 2025

    Bib

    @inproceedings{WAKITA_2025_JSAP-SPRING,
      author = {脇田耀介 and 宮武悠人 and 大野修平 and 赤澤智熙 and 牧野孝太郎 and 畑山祥吾 and モンフレ・ステファン and ブフ・フレデリック and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第72回応用物理学会春季学術講演会},
      title = {III-V/Siハイブリッド導波路向けSb<sub>2</sub>S<sub>3</sub>不揮発光位相シフタの検証},
      year = {2025},
      volume = {},
      number = {16ppK305-5},
      pages = {},
      month = mar,
    }

2024

1. JJAP

   

   Compact, low-loss, and broadband 2×2 Si optical coupler designed by covariance matrix adaptation evolution strategy

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   Japanese Journal of Applied Physics, Dec 2024

   JSAP Outstanding Paper Award (JSAP Young Scientist Award) Abs DOI Bib

   

   Yuto Miyatake received 47th JSAP Outstanding Paper Award (JSAP Young Scientist Award). This award is presented to outstanding young researchers who are expected to contribute significantly to the progress and advancement of applied physics. It is granted to the first author of exceptional papers published in the Japanese Journal of Applied Physics (JJAP) or Applied Physics Express (APEX).

   We experimentally demonstrate compact, low-loss, and broadband 2×2 Si optical couplers on a Si photonic platform designed using the covariance matrix adaptation evolution strategy (CMA-ES). The measured minimum insertion losses (ILs) in the C-band were 0.071 dB, 0.016 dB, 0.016 dB, and 45%–55% optical bandwidth were 140 nm, 136 nm, and 139 nm for device lengths of 7.56 μm, 9.64 μm, and 12.32 μm, respectively. The ILs are smaller than ever reported in 2 × 2 optical couplers shorter than 10 μm, and the optical bandwidths are much larger than a conventional directional coupler. The results validate the effectiveness of the proposed CMA-ES-based design method, extending the scope of application of our design method to the design of passive devices on Si photonics platform.

   @article{MIYATAKE_2024_JJAP,
     doi = {10.35848/1347-4065/ad983b},
     url = {https://doi.org/10.35848/1347-4065/ad983b},
     year = {2024},
     month = dec,
     publisher = {IOP Publishing},
     volume = {63},
     number = {12},
     pages = {12SP16},
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     title = {Compact, low-loss, and broadband 2×2 Si optical coupler designed by covariance matrix adaptation evolution strategy},
     journal = {Japanese Journal of Applied Physics},
   }

2. JLT

   

   Photonic Matrix-Vector Multiplication With Low-Insertion-Loss and Non-Volatile Ge₂Sb₂Te₃S₂ Intensity Modulators

   Yuto Miyatake, Rui Tang, Kotaro Makino, and 6 more authors

   Journal of Lightwave Technology, Jun 2024

   Yasujirou Niwa Memorial Paper Award Abs DOI Bib

   

   Yuto Miyatake received the 49th Yasujirou Niwa Memorial Paper Award for this paper. This award is presented to young researchers who have conducted original research and published outstanding papers in the fields related to electronic and communication engineering (broadly including information engineering, electrical engineering, and related areas). It was established in 1977 in honor of Dr. Yasujirō Niwa, the first president of Tokyo Denki University, to commemorate his achievements.

   We propose a low-insertion-loss (IL) and non-volatile optical intensity modulator based on Ge₂Sb₂Te₃S₂ (GSTS), a recently proposed Se-free wide-gap phase change material. Owing to the negligibly small optical absorption of amorphous GSTS at a wavelength of 1550 nm, a non-volatile intensity modulator with a low IL of less than 0.08 dB and a high extinction ratio (ER) of 19.6 dB is realized using GSTS with a device length of 8 μm, overcoming the trade-off relationship between IL and ER in conventional Ge₂Sb₂Te₅ (GST). Using visible laser light irradiation, we demonstrate multilevel modulation up to 24 levels by taking advantage of the small optical absorption of amorphous GSTS and the moderately large optical absorption of crystalline GSTS compared with GST. With the proposed GSTS intensity modulators, we demonstrate 4×4 matrix-vector multiplication using a recently proposed photonic tensor core, which shows a high tolerance to hardware error accumulation. On the basis of the experimental results, we numerically confirm that a high recognition accuracy of 97.33% can be obtained using a convolutional neural network with emulated optical convolutional operations.

   @article{MIYATAKE_2024_JLT,
     author = {Miyatake, Yuto and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Journal of Lightwave Technology},
     title = {Photonic Matrix-Vector Multiplication With Low-Insertion-Loss and Non-Volatile Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> Intensity Modulators},
     year = {2024},
     volume = {42},
     number = {12},
     pages = {4347-4354},
     keywords = {Modulation;Optical modulation;Photonics;Tensors;Pulse modulation;Adaptive optics;Transmission line matrix methods;Non-volatile intensity modulator;phase change materials;photonic matrix multiplication;photonic tensor core},
     doi = {10.1109/JLT.2024.3408877},
     issn = {1558-2213},
     month = jun,
   }

3. JLT

   Add-Drop Microring Resonator Switch With Positive/Negative Phase Tuning Using InGaAsP/Si Hybrid MOS Phase Shifter

   Yosuke Wakita, Rui Tang, Hanzhi Tang, and 8 more authors

   Journal of Lightwave Technology, Jun 2024

   Abs DOI Bib

   

   We successfully demonstrated an add-drop Si microring resonator switch using an InGaAsP/Si hybrid metal-oxide-semiconductor (MOS) optical phase shifter. We revealed that a Si shallow rib waveguide is effective to achieve a quasi-single-mode microring resonator, even when employing a 200-nm-thick InGaAsP membrane on the Si ring waveguide. Owing to the careful design in the Si waveguide, we experimentally demonstrated the well-behaved add-drop switching operation using the InGaAs/Si hybrid MOS phase shifter with a modulation efficiency of 0.53 Vcm. The integration of a 200-nm-thick InGaAsP enabled both positive and negative phase tuning through carrier accumulation and depletion at the InGaAsP MOS interface. As a result, the modulation efficiency was improved by a factor of 7.5, compared to the hybrid MOS phase shifter utilizing a 25-nm-thick InP membrane. With an insignificant gate leakage current, we achieved an exceptionally low switching power of 150 fW. Additionally, the measured switching time was less than 6 ns. These characteristics make the demonstrated add-drop microring resonator switch highly promising for wavelength division multiplexed programmable photonic integrated circuits.

   @article{WAKITA_2024_JLT,
     author = {Wakita, Yosuke and Tang, Rui and Tang, Hanzhi and Ohno, Shuhei and Akazawa, Tomohiro and Miyatake, Yuto and Monfray, Stephane and Boeuf, Frederic and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Journal of Lightwave Technology},
     title = {Add-Drop Microring Resonator Switch With Positive/Negative Phase Tuning Using InGaAsP/Si Hybrid MOS Phase Shifter},
     year = {2024},
     volume = {42},
     number = {12},
     pages = {4289-4295},
     keywords = {Optical waveguides;Optical switches;Optical ring resonators;Phase shifters;Optical device fabrication;Silicon photonics;III-V semiconductor materials;Optical modulators;Heterogeneous integration;III-V compound semiconductor;microring resonator;optical modulator;optical phase shifter;optical switch;Si photonics},
     doi = {10.1109/JLT.2024.3383724},
     issn = {1558-2213},
     month = jun,
   }

4. Nat. Commun.

   Nonvolatile optical phase shift in ferroelectric hafnium zirconium oxide

   Kazuma Taki, Naoki Sekine, Kouhei Watanabe, and 6 more authors

   Nature Communications, 2024

   Abs DOI Bib

   

   A nonvolatile optical phase shifter is a critical component for enabling the fabrication of programmable photonic integrated circuits on a Si photonics platform, facilitating communication, computing, and sensing. Although ferroelectric materials such as BaTiO3 offer nonvolatile optical phase shift capabilities, their compatibility with complementary metal-oxide-semiconductor fabs is limited. Hf_0.5Zr_0.5O₂ is an emerging ferroelectric material, which exhibits complementary metal-oxide-semiconductor compatibility. Although extensively studied for ferroelectric transistors and memories, its application to photonics remains relatively unexplored. Here, we show the optical phase shift induced by ferroelectric Hf_0.5Zr_0.5O₂. We observed a negative change in refractive index at a 1.55 μm wavelength in a pristine device regardless of the direction of the applied electric field. The nonvolatile phase shift was only observed once in a pristine device. This non-reversible phase shift can be attributed to the spontaneous polarization within the Hf_0.5Zr_0.5O₂ film along the external electric field.

   @article{TAKI_2024_NCOM,
     title = {Nonvolatile optical phase shift in ferroelectric hafnium zirconium oxide},
     author = {Taki, Kazuma and Sekine, Naoki and Watanabe, Kouhei and Miyatake, Yuto and Akazawa, Tomohiro and Sakumoto, Hiroya and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Nature Communications},
     volume = {15},
     number = {1},
     pages = {3549},
     year = {2024},
     publisher = {Nature Publishing Group UK London},
     doi = {10.1038/s41467-024-47893-2},
   }

5. JJAP

   Numerical evaluation of bandwidth and optical loss in InP-organic hybrid optical modulator with doping optimization

   Hiroya Sakumoto, Taketoshi Nakayama, Yuto Miyatake, and 3 more authors

   Japanese Journal of Applied Physics, Jan 2024

   Abs DOI Bib

   

   We examine the influence of doping profile optimization on the trade-off relationship between modulation bandwidth and optical loss in an InP-organic hybrid (IOH) optical modulator, comparing it with a Si-organic hybrid (SOH) optical modulator. By incorporating the RF transmission line model, which enables a more precise modulation bandwidth analysis than the RC constant model, we demonstrate that the IOH modulator can achieve a modulation bandwidth of over 500 GHz with a 2 dB loss, capitalizing on the higher electron mobility of InP. In contrast, the SOH modulator cannot attain a 200 GHz modulation bandwidth with acceptable optical loss. Furthermore, we explore the potential for further enhancing the modulation bandwidth of the IOH modulator by shortening its length, making the IOH modulator a promising candidate for future ultra-high-speed optical modulation.

   @article{SAKUMOTO_2024_JJAP,
     doi = {10.35848/1347-4065/ad189b},
     url = {https://doi.org/10.35848/1347-4065/ad189b},
     year = {2024},
     month = jan,
     publisher = {IOP Publishing},
     volume = {63},
     number = {2},
     pages = {02SP52},
     author = {Sakumoto, Hiroya and Nakayama, Taketoshi and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     title = {Numerical evaluation of bandwidth and optical loss in InP-organic hybrid optical modulator with doping optimization},
     journal = {Japanese Journal of Applied Physics},
   }

6. SSDM

   Experimental demonstration of compact, low-loss and broadband 22 Si optical coupler designed by CMA-ES

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   In International Conference on Solid State Devices and Materials (SSDM), 2024

   Bib

   @inproceedings{MIYATAKE_2024_SSDM,
     title = {Experimental demonstration of compact, low-loss and broadband 22 Si optical coupler designed by CMA-ES},
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {International Conference on Solid State Devices and Materials (SSDM)},
     pages = {1--4},
     year = {2024},
     organization = {JSAP},
   }

7. MRS

   Development of optical phase change materials for non-volatile photonics

   Kotaro Makino, Yuto Miyatake, Shogo Hatayama, and 2 more authors

   In MRS Fall Meeting, Dec 2024

   Bib

   @inproceedings{MAKINO_2024_MRS,
     author = {Makino, Kotaro and Miyatake, Yuto and Hatayama, Shogo and Takenaka, Mitsuru and Tominaga, Junji},
     booktitle = {MRS Fall Meeting},
     title = {Development of optical phase change materials for non-volatile photonics},
     year = {2024},
     volume = {},
     number = {EL02.08.03},
     pages = {1-6},
     month = dec,
   }

8. ISPEC

   Non-volatile Ge₂Sb₂Te₃S₂ driven Si microring resonator switch for photonic matrix multiplication

   Kenji Kobayashi, Yuto Miyatake, Rui Tang, and 7 more authors

   In 14th International Symposium on Photonics and Electronics Convergence (ISPEC), Nov 2024

   Bib

   @inproceedings{KOBAYASHI_2024_ISPEC,
     title = {Non-volatile Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> driven Si microring resonator switch for photonic matrix multiplication},
     author = {Kobayashi, Kenji and Miyatake, Yuto and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {14th International Symposium on Photonics and Electronics Convergence (ISPEC)},
     number = {P-16},
     year = {2024},
     month = nov,
   }

9. ISPEC

   InGaAs-based plasmonic photodetector using Ni-InGaAs alloy

   Kentaro Komatsu, Taketoshi Nakayama, Tomohiro Akazawa, and 10 more authors

   In 14th International Symposium on Photonics and Electronics Convergence (ISPEC), Nov 2024

   Bib

   @inproceedings{KOMATSU_2024_ISPEC,
     title = {InGaAs-based plasmonic photodetector using Ni-InGaAs alloy},
     author = {Komatsu, Kentaro and Nakayama, Taketoshi and Akazawa, Tomohiro and Wakita, Yosuke and Sakumoto, Hiroya and Zhang, Chao and Miyatake, Yuto and Monfray, Stéphane and Boeuf, Frédéric and Tang, Rui and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {14th International Symposium on Photonics and Electronics Convergence (ISPEC)},
     number = {P-13},
     year = {2024},
     month = nov,
   }

10. ISPEC

    InP-Si interlayer optimization using GPU-accelerated CMA-ES

    Hiroya Sakumoto, Yuto Miyatake, Kasidit Toprasertpong, and 2 more authors

    In 14th International Symposium on Photonics and Electronics Convergence (ISPEC), Nov 2024

    Bib

    @inproceedings{SAKUMOTO_2024_ISPEC,
      title = {InP-Si interlayer optimization using GPU-accelerated CMA-ES},
      author = {Sakumoto, Hiroya and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
      booktitle = {14th International Symposium on Photonics and Electronics Convergence (ISPEC)},
      number = {P-11},
      year = {2024},
      month = nov,
    }

11. ECOC

    Plasmonic Photodetector with InGaAs Membrane on Si Waveguide using Ni-InGaAs Alloy

    Kentaro Komatsu, Taketoshi Nakayama, Tomohiro Akazawa, and 10 more authors

    In ECOC 2024; 50th European Conference on Optical Communication, Sep 2024

    Abs DOI Bib

    

    We demonstrate III-V/Si hybrid plasmonic waveguide photodetector with InGaAs membrane. Alloying between InGaAs and Ni enables the simple fabrication of plasmonic structure. We achieve 0.13 A/W responsivity at 1 V with 400 nA dark current, demonstrating the potential for low-voltage and high-speed InGaAs plasmonic photodetectors.

    @inproceedings{KOMATSU_2024_ECOC,
      author = {Komatsu, Kentaro and Nakayama, Taketoshi and Akazawa, Tomohiro and Wakita, Yosuke and Sakumoto, Hiroya and Zhang, Chao and Miyatake, Yuto and Monfray, Stephane and Boeuf, Frederic and Tang, Rui and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
      booktitle = {ECOC 2024; 50th European Conference on Optical Communication},
      title = {Plasmonic Photodetector with InGaAs Membrane on Si Waveguide using Ni-InGaAs Alloy},
      year = {2024},
      volume = {},
      number = {},
      pages = {706-709},
      keywords = {},
      doi = {},
      issn = {},
      month = sep,
    }

12. IPC

    Si programmable photonic integrated circuits based on phase change materials

    Mitsuru Takenaka, Yuto Miyatake, Rui Tang, and 6 more authors

    In IEEE Si Photonics Conference, Apr 2024

    Bib

    @inproceedings{TAKENAKA_2024_IPC,
      author = {Takenaka, Mitsuru and Miyatake, Yuto and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi},
      booktitle = {IEEE Si Photonics Conference},
      title = {Si programmable photonic integrated circuits based on phase change materials},
      year = {2024},
      volume = {},
      number = {ThD2, invited},
      month = apr,
    }

13. JSAP

    異種材料集積を用いたAI用光回路

    竹中充, 唐睿, 宮武悠人, and 20 more authors

    In 第85回応用物理学会秋季学術講演会, Sep 2024

    Bib

    @inproceedings{TAKENAKA_2024_JSAP-AUTUMN,
      author = {竹中充 and 唐睿 and 宮武悠人 and 柴成立 and 赤澤智熙 and 作本宙彌 and 脇田耀介 and バルダワジ, ダルワ イシャン and 按田智大 and 高城和馬 and 関根尚希 and 渡辺耕坪 and 大野修平 and 谷澤健 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 池田和浩 and 岡野誠 and モンフレ, ステファン and ブフ, フレデリック and トープラサートポン, カシディット and 高木信一},
      booktitle = {第85回応用物理学会秋季学術講演会},
      title = {異種材料集積を用いたAI用光回路},
      year = {2024},
      volume = {},
      number = {18p-C302-6, 招待講演},
      pages = {},
      month = sep,
    }

14. JSAP

    GPUを用いた進化戦略計算によるInP-Siレイヤ間遷移光導波路設計

    作本宙彌, 宮武悠人, トープラサートポンカシディット, and 2 more authors

    In 第85回応用物理学会秋季学術講演会, Sep 2024

    Bib

    @inproceedings{SAKUMOTO_2024_JSAP-AUTUMN,
      author = {作本宙彌 and 宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中, 充},
      booktitle = {第85回応用物理学会秋季学術講演会},
      title = {GPUを用いた進化戦略計算によるInP-Siレイヤ間遷移光導波路設計},
      year = {2024},
      volume = {},
      number = {16a-A25-5},
      pages = {},
      month = sep,
    }

15. JSAP

    Ni-InGaAs合金を用いたInGaAs-Siハイブリッドプラズモニック導波路受光器

    小松健太郎, 中山武壽, 赤澤智熈, and 10 more authors

    In 第85回応用物理学会秋季学術講演会, Sep 2024

    Bib

    @inproceedings{KOMATSU_2024_JSAP-AUTUMN,
      author = {小松健太郎 and 中山武壽 and 赤澤智熈 and 脇田耀介 and 作本宙彌 and 張超 and 宮武悠人 and モンフレ・ステファン and ブフ・フレデリック and 唐睿 and トープラサートポン・カシディット and 高木信一 and 竹中, 充},
      booktitle = {第85回応用物理学会秋季学術講演会},
      title = {Ni-InGaAs合金を用いたInGaAs-Siハイブリッドプラズモニック導波路受光器},
      year = {2024},
      volume = {},
      number = {16p-A25-15},
      pages = {},
      month = sep,
    }

16. JSAP

    Investigation of linear electro-optic effect in ferroelectric hafnium zirconium oxide on SiN waveguide

    Dhruv Ishan Bhardwaj, Kazuma Taki, Naoki Sekine, and 7 more authors

    In 第85回応用物理学会秋季学術講演会, Sep 2024

    Bib

    @inproceedings{BHARDWAJ_2024_JSAP-AUTUMN,
      author = {Bhardwaj, Dhruv Ishan and Taki, Kazuma and Sekine, Naoki and Watanabe, Kohei and Miyatake, Yuto and Akazawa, Tomohiro and Sakumoto, Hiroya and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
      booktitle = {第85回応用物理学会秋季学術講演会},
      title = {Investigation of linear electro-optic effect in ferroelectric hafnium zirconium oxide on SiN waveguide},
      year = {2024},
      volume = {},
      number = {16p-A25-3},
      pages = {},
      month = sep,
    }

17. JSAP

    低損失光位相シフタに向けたSb₂S₃の最適成膜条件の探索

    按田智大, 宮武悠人, 牧野孝太郎, and 6 more authors

    In 第71回応用物理学会春季学術講演会, Mar 2024

    Bib

    @inproceedings{ANDA_2024_JSAP-SPRING,
      author = {按田智大 and 宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 岡野誠 and トープラサートポン・シディット and 高木信一 and 竹中充},
      booktitle = {第71回応用物理学会春季学術講演会},
      title = {低損失光位相シフタに向けたSb<sub>2</sub>S<sub>3</sub>の最適成膜条件の探索},
      year = {2024},
      volume = {},
      number = {22p-11F-12},
      pages = {},
      month = mar,
    }

18. LSJ

    相変化材料Ge₂Sb₂Te₃S₂を用いたプログラマブル光回路

    竹中充, 宮武悠人, 牧野孝太郎, and 6 more authors

    In レーザー学会第44回年次大会, Jan 2024

    Bib

    @inproceedings{TAKENAKA_2024_LSJ,
      author = {竹中充 and 宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 岡野誠 and トープラサートポンカシディット and 高木信一},
      booktitle = {レーザー学会第44回年次大会},
      title = {相変化材料Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>を用いたプログラマブル光回路},
      year = {2024},
      volume = {},
      number = {招待講演},
      pages = {},
      month = jan,
    }

2023

1. OE

   

   Design of compact and low-loss S-bends by CMA-ES

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   Opt. Express, Dec 2023

   Abs DOI Bib

   

   We employ the covariance matrix adaptation evolution strategy (CMA-ES) algorithm to design compact and low-loss S-bends on the standard silicon-on-insulator platform. In line with the CMA-ES-based approach, we present experimental results demonstrating insertion losses of 0.041 dB, 0.025 dB, and 0.011 dB for S-bends with sizes of 3.5 \textmum, 4.5 \textmum, and 5.5 \textmum, respectively, which are the lowest insertion losses within the footprint range smaller than approximately 30 \textmum2. These outcomes underscore the remarkable performance and adaptability of the CMA-ES to design Si photonics devices tailored for high-density photonic integrated circuits.

   @article{MIYATAKE_2023_OE,
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Opt. Express},
     keywords = {Coupling efficiency; Genetic algorithms; Inverse design; Neural networks; Optical modulators; Photonic crystals},
     number = {26},
     pages = {43850--43863},
     publisher = {Optica Publishing Group},
     title = {Design of compact and low-loss S-bends by CMA-ES},
     volume = {31},
     month = dec,
     year = {2023},
     url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-31-26-43850},
     doi = {10.1364/OE.504866},
   }

2. T-ED

   

   Proposal of Low-Loss Non-Volatile Mid-Infrared Optical Phase Shifter Based on Ge₂Sb₂Te₃S₂

   Yuto Miyatake, Kotaro Makino, Junji Tominaga, and 6 more authors

   IEEE Transactions on Electron Devices, Apr 2023

   Abs DOI Bib

   

   An optical phase shifter based on phase-change materials (PCMs) is a promising building block of quantum photonic integrated circuits (QPICs) operating at mid-infrared (MIR) wavelengths on a Si photonics platform. In this article, we propose a record low-loss non-volatile PCM phase shifter operating at MIR wavelengths based on Ge₂Sb₂Te₃S₂ (GSTS), which is a new Se-free widegap PCM. On the basis of the refractive index and extinction coefficient spectra measured by spectroscopic ellipsometry, we show that GSTS has excellent material properties for optical phase shifters. By using GSTS in the MIR range, the optical absorption of a PCM phase shifter can be considerably reduced. We achieved an optical loss of 0.29 dB for a \pi phase shift, which is the lowest loss ever reported for a PCM phase shifter integrated with a Si waveguide. We also demonstrate the non-volatile resonance wavelength tuning of a microring resonator (MRR) with a GSTS phase shifter and the optically induced phase transition of a GSTS phase shifter based on laser irradiation.

   @article{MIYATAKE_2023_TED,
     author = {Miyatake, Yuto and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {IEEE Transactions on Electron Devices},
     title = {Proposal of Low-Loss Non-Volatile Mid-Infrared Optical Phase Shifter Based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>},
     year = {2023},
     volume = {70},
     number = {4},
     pages = {2106-2112},
     keywords = {Phase shifters;Phase change materials;Optical variables control;Optical refraction;Optical losses;Silicon;Photonic band gap;Mid-infrared (MIR);non-volatile;phase-change material (PCM);phase shifter},
     doi = {10.1109/TED.2023.3235865},
     issn = {1557-9646},
     month = apr,
   }

3. ISPEC

   Photonic matrix multiplication with Ge₂Sb₂Te₃S₂ intensity modulators

   Yuto Miyatake, Rui Tang, Kotaro Makino, and 7 more authors

   In 13th International Symposium on Photonics and Electronics Convergence (ISPEC2023), Nov 2023

   Bib

   @inproceedings{MIYATAKE_2023_ISPEC,
     title = {Photonic matrix multiplication with Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> intensity modulators},
     author = {Miyatake, Yuto and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashiand and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {13th International Symposium on Photonics and Electronics Convergence (ISPEC2023)},
     pages = {1--2},
     number = {P-27},
     year = {2023},
     month = nov,
   }

4. ECOC

   Photonic tensor core with low-insertion-loss, non-volatile Ge₂Sb₂Te₃S₂ intensity modulators

   Y. Miyatake, R. Tang, K. Makino, and 6 more authors

   In 49th European Conference on Optical Communications (ECOC 2023), Oct 2023

   Abs DOI Bib

   

   We proposed a low-insertion-loss and non-volatile optical intensity modulator based on Ge₂Sb₂Te₃S₂ (GSTS), a recently proposed widegap phase change material. We demonstrated matrix-vector multiplication using a new photonic tensor core with GSTS intensity modulators, enabling a high recognition accuracy of 97.34 % in CNN.

   @inproceedings{MIYATAKE_2023_ECOC,
     author = {Miyatake, Y. and Tang, R. and Makino, K. and Tominaga, J. and Miyata, N. and Okano, M. and Toprasertpong, K. and Takagi, S. and Takenaka, M.},
     booktitle = {49th European Conference on Optical Communications (ECOC 2023)},
     title = {Photonic tensor core with low-insertion-loss, non-volatile Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> intensity modulators},
     year = {2023},
     volume = {2023},
     number = {},
     pages = {432-435},
     keywords = {},
     doi = {10.1049/icp.2023.2098},
     issn = {},
     month = oct,
   }

5. CLEO

   Compact Low-loss S-bends Designed by CMA-ES

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   In 2023 Conference on Lasers and Electro-Optics (CLEO), May 2023

   Abs DOI Bib

   

   Based on a design method by CMA-ES, we experimentally demonstrated an ultra-compact S-bend with an insertion loss of 0.011 dB, which is the lowest value in the footprint range smaller than around 30 μm2.

   @inproceedings{MIYATAKE_2023_CLEO,
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {2023 Conference on Lasers and Electro-Optics (CLEO)},
     title = {Compact Low-loss S-bends Designed by CMA-ES},
     year = {2023},
     volume = {},
     number = {},
     pages = {1-2},
     keywords = {Design methodology;Insertion loss;Lasers and electrooptics;Electrooptical waveguides},
     doi = {},
     issn = {2160-8989},
     month = may,
   }

6. ISPEC

   Evaluation of the impact of the doping optimization on the modulation bandwidth and the optical loss of the InP-EO polymer hybrid optical modulator

   Hiroya Sakumoto, Taketoshi Nakayama, Yuto Miyatake, and 3 more authors

   In 13th International Symposium on Photonics and Electronics Convergence (ISPEC2023), Nov 2023

   Bib

   @inproceedings{SAKUMOTO_2023_ISPEC,
     title = {Evaluation of the impact of the doping optimization on the modulation bandwidth and the optical loss of the InP-EO polymer hybrid optical modulator},
     author = {Sakumoto, Hiroya and Nakayama, Taketoshi and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {13th International Symposium on Photonics and Electronics Convergence (ISPEC2023)},
     number = {P-12},
     year = {2023},
     month = nov,
   }

7. ISPEC

   Ge avalanche photodiode integrated with microring resonator for 2 µm wavelengths on Ge-on-insulator platform

   Chao Zhang, Ziqiang Zhao, Rui Tang, and 5 more authors

   In 13th International Symposium on Photonics and Electronics Convergence (ISPEC2023), Nov 2023

   Bib

   @inproceedings{ZHANG_2023_ISPEC,
     title = {Ge avalanche photodiode integrated with microring resonator for 2 µm wavelengths on Ge-on-insulator platform},
     author = {Zhang, Chao and Zhao, Ziqiang and Tang, Rui and Akazawa, Tomohiro and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {13th International Symposium on Photonics and Electronics Convergence (ISPEC2023)},
     number = {P-12},
     year = {2023},
     month = nov,
   }

8. ECOC

   Low-power add-drop microring resonator switch with positive/negative phase tuning using InGaAsP/Si hybrid MOS phase shifter

   Y. Wakita, R. Tang, H. Tang, and 8 more authors

   In 49th European Conference on Optical Communications (ECOC 2023), Oct 2023

   Abs DOI Bib

   

   We demonstrated add-drop Si microring resonator switch using InGaAsP/Si hybrid MOS optical phase shifter. Through careful Si waveguide design, quasi-single-mode add-drop operation with bipolar phase tuning was achieved. Owing to negligible gate leakage current, high extinction ratio of 34 dB was obtained with150 fW.

   @inproceedings{WAKITA_2023_ECOC,
     author = {Wakita, Y. and Tang, R. and Tang, H. and Ohno, S. and Akazawa, T. and Miyatake, Y. and Monfray, S. and Boeuf, F. and Toprasertpong, K. and Takagi, S. and Takenaka, M.},
     booktitle = {49th European Conference on Optical Communications (ECOC 2023)},
     title = {Low-power add-drop microring resonator switch with positive/negative phase tuning using InGaAsP/Si hybrid MOS phase shifter},
     year = {2023},
     volume = {2023},
     number = {},
     pages = {322-325},
     keywords = {},
     doi = {10.1049/icp.2023.2070},
     issn = {},
     month = oct,
   }

9. SSDM

   Numerical evaluation of modulation bandwidth and insertion loss in InP-EO polymer hybrid optical modulator with doping optimization

   Hiroya Sakumoto, Taketoshi Nakayama, Yuto Miyatake, and 3 more authors

   In International Conference on Solid State Devices and Materials (SSDM2023), Sep 2023

   Bib

   @inproceedings{SAKUMOTO_2023_SSDM,
     title = {Numerical evaluation of modulation bandwidth and insertion loss in InP-EO polymer hybrid optical modulator with doping optimization},
     author = {Sakumoto, Hiroya and Nakayama, Taketoshi and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {International Conference on Solid State Devices and Materials (SSDM2023)},
     number = {H-7-04},
     year = {2023},
     month = sep,
   }

10. OAPC

    Scalable programmable photonic integrated circuits by III-V/Si hybrid integration

    Mitsuru Takenaka, Hanzhi Tang, Kohei Watanabe, and 17 more authors

    In Optica Advanced Photonics Congress (OAPC), Jul 2023

    Bib

    @inproceedings{TAKENAKA_2023_OAPC,
      author = {Takenaka, Mitsuru and Tang, Hanzhi and Watanabe, Kohei and Ochiai, Takaya and Akazawa, Tomohiro and Huang, Ming and Wakita, Yosuke and Miyatake, Yuto and Ohno, Shuhei and Sumita, Kei and Monfray, Sylvain and Boeuf, Frédéric and Tang, Rui and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi},
      booktitle = {Optica Advanced Photonics Congress (OAPC)},
      title = {Scalable programmable photonic integrated circuits by III-V/Si hybrid integration},
      year = {2023},
      volume = {},
      number = {invited},
      month = jul,
    }

11. JSAP

    低挿入損失・不揮発性Ge₂Sb₂Te₃S₂強度変調器を用いた光行列演算

    宮武悠人, 唐睿, 牧野孝太郎, and 6 more authors

    In 第84回応用物理学会秋季学術講演会, Sep 2023

    Abs Bib

    プログラミングの容易さと高い作製誤差耐性を両立する光回路として、最近我々は二層導波路を用いた新しい光行列演算回路を提案した。今回、新規に開発した相変化材料Ge₂Sb₂Te₃S₂（GSTS）を用いた強度変調器を提案回路に集積した行列演算回路を作製し、4×4の行列演算を行った。実験結果に基づいて畳み込みニューラルネットワークの推論計算をシミュレーションし、高い精度で推論が行えることを数値的に示した。

    @inproceedings{MIYATAKE_2023_JSAP-AUTUMN,
      author = {宮武悠人 and 唐睿 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第84回応用物理学会秋季学術講演会},
      title = {低挿入損失・不揮発性Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>強度変調器を用いた光行列演算},
      year = {2023},
      volume = {},
      number = {20p-A201-5},
      pages = {},
      month = sep,
    }

12. JSAP

    Ge₂Sb₂Te₃S₂に基づく不揮発性相変化中赤外光位相シフタの低損失化

    宮武悠人, 牧野孝太郎, 富永淳二, and 6 more authors

    In 第70回応用物理学会春季学術講演会, Mar 2023

    Bib

    @inproceedings{MIYATAKE_2023_JSAP-SPRING,
      author = {宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第70回応用物理学会春季学術講演会},
      title = {Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>に基づく不揮発性相変化中赤外光位相シフタの低損失化},
      year = {2023},
      volume = {},
      number = {15p-A502-8},
      pages = {},
      month = mar,
    }

13. IEEJ

    Ge₂Sb₂Te₃S₂を用いた不揮発性相変化中赤外光位相シフタ

    宮武悠人, 牧野孝太郎, 富永淳二, and 6 more authors

    In 電気学会ナノエレクトロニクス機能化・応用技術調査専門委員会, Mar 2023

    Bib

    @inproceedings{MIYATAKE_2023_IEEJ,
      author = {宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {電気学会ナノエレクトロニクス機能化・応用技術調査専門委員会},
      title = {Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>を用いた不揮発性相変化中赤外光位相シフタ},
      year = {2023},
      volume = {},
      number = {招待講演},
      pages = {},
      month = mar,
    }

14. IEICE

    Ge₂Sb₂Te₃S₂を用いた不揮発性相変化中赤外光位相シフタ

    宮武悠人, 牧野孝太郎, 富永淳二, and 6 more authors

    In 電子情報通信学会シリコン材料・デバイス研究会（SDM）, Mar 2023

    Bib

    @inproceedings{MIYATAKE_2023_IEICE,
      author = {宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 岡野誠 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {電子情報通信学会シリコン材料・デバイス研究会（SDM）},
      title = {Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub>を用いた不揮発性相変化中赤外光位相シフタ},
      year = {2023},
      volume = {},
      number = {招待講演},
      pages = {},
      month = mar,
    }

15. PCOS

    Non-volatile optical devices based on Ge₂Sb₂Te₃S₂ on Si photonics platform for computing applications

    Mitsuru Takenaka, Yuto Miyatake, Kotaro Makino, and 7 more authors

    In 相変化研究会, Nov 2023

    Bib

    @inproceedings{TAKENAKA_2023_PCOS,
      author = {Takenaka, Mitsuru and Miyatake, Yuto and Makino, Kotaro and Tang, Rui and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinich},
      booktitle = {相変化研究会},
      title = {Non-volatile optical devices based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>3</sub>S<sub>2</sub> on Si photonics platform for computing applications},
      year = {2023},
      volume = {},
      number = {招待講演},
      pages = {},
      month = nov,
    }

16. JSAP

    Germanium microring resonator avalanche photodiode for 2 µm wavelengths on Ge-on-insulator platform

    Chao Zhang, Ziqiang Zhao, Rui Tang, and 5 more authors

    In 第84回応用物理学会秋季学術講演会, Sep 2023

    Bib

    @inproceedings{ZHANG_2023_JSAP-AUTUMN,
      author = {Zhang, Chao and Zhao, Ziqiang and Tang, Rui and Akazawa, Tomohiro and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
      booktitle = {第84回応用物理学会秋季学術講演会},
      title = {Germanium microring resonator avalanche photodiode for 2 µm wavelengths on Ge-on-insulator platform},
      year = {2023},
      volume = {},
      number = {20p-A201-13},
      pages = {},
      month = sep,
    }

17. JSAP

    強誘電体Hf_0.5Zr_0.5O₂における不揮発的位相変化の観測

    高城和馬, 関根尚希, 宮武悠人, and 3 more authors

    In 第70回応用物理学会春季学術講演会, Mar 2023

    Bib

    @inproceedings{TAKI_2023_JSAP-SPRING,
      author = {高城和馬 and 関根尚希 and 宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第70回応用物理学会春季学術講演会},
      title = {強誘電体Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>における不揮発的位相変化の観測},
      year = {2023},
      volume = {},
      number = {15p-A502-9},
      pages = {},
      month = mar,
    }

18. JSAP

    ドーピング最適化によるInP-EOポリマーハイブリッド光変調器の高速化、低損失化の検証

    作本宙彌, 中山武壽, 宮武悠人, and 3 more authors

    In 第70回応用物理学会春季学術講演会, Mar 2023

    Bib

    @inproceedings{SAKUMOTO_2023_JSAP-SPRING,
      author = {作本宙彌 and 中山武壽 and 宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第70回応用物理学会春季学術講演会},
      title = {ドーピング最適化によるInP-EOポリマーハイブリッド光変調器の高速化、低損失化の検証},
      year = {2023},
      volume = {},
      number = {16a-A409-8},
      pages = {},
      month = mar,
    }

2022

1. OME

   

   Non-volatile compact optical phase shifter based on Ge₂Sb₂Te₅ operating at 2.3 µm

   Yuto Miyatake, Chong Pei Ho, Prakash Pitchappa, and 8 more authors

   Opt. Mater. Express, Dec 2022

   Abs DOI Bib

   

   We investigate an optical phase shifter based on Ge₂Sb₂Te₅ (GST) integrated with a Si waveguide at mid-infrared (MIR) wavelengths. Since the optical absorption of both amorphous and crystalline GST can be reduced at a longer wavelength, we demonstrate that the optical loss of the phase shifter can be reduced at MIR wavelengths. The measured optical loss per π phase shift of a phase-change material (PCM) phase shifter at 2.32 µm wavelength is 2.6 dB/π, which is more than 80 times smaller than that at 1.55 µm wavelength (21.7 dB/π) and more than 5 times smaller than that at 1.92 µm wavelength (9.7 dB/π). Moreover, resonance wavelength tuning of an add-drop micro-ring resonator using a PCM phase shifter at 2.32 µm wavelength is demonstrated owing to the low-loss optical phase shift. These findings reinforce the applicability of the approach toward a low-loss optical phase shifter based on PCMs operating at MIR wavelengths on a Si photonic platform for quantum computing, sensing, and optical communication.

   @article{MIYATAKE_2022_OME,
     author = {Miyatake, Yuto and Ho, Chong Pei and Pitchappa, Prakash and Singh, Ranjan and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Opt. Mater. Express},
     keywords = {Lidar; Material properties; Optical absorption; Phase shift; Photonic quantum computing; Rayleigh scattering},
     number = {12},
     pages = {4582--4593},
     publisher = {Optica Publishing Group},
     title = {Non-volatile compact optical phase shifter based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> operating at 2.3 \&\#x00B5;m},
     volume = {12},
     month = dec,
     year = {2022},
     url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-12-12-4582},
     doi = {10.1364/OME.473987},
   }

2. Nat. Commun.

   Ultrahigh-responsivity waveguide-coupled optical power monitor for Si photonic circuits operating at near-infrared wavelengths

   Takaya Ochiai, Tomohiro Akazawa, Yuto Miyatake, and 7 more authors

   Nature Communications, 2022

   Abs DOI Bib

   

   A phototransistor is a promising candidate as an optical power monitor in Si photonic circuits since the internal gain of photocurrent enables high responsivity. However, state-of-the-art waveguide-coupled phototransistors suffer from a responsivity of lower than 103 A/W, which is insufficient for detecting very low power light. Here, we present a waveguide-coupled phototransistor operating at a 1.3 μm wavelength, which consists of an InGaAs ultrathin channel on a Si waveguide working as a gate electrode to increase the responsivity. The Si waveguide gate underneath the InGaAs ultrathin channel enables the effective control of transistor current without optical absorption by the gate metal. As a result, our phototransistor achieved the highest responsivity of approximately 106 A/W among the waveguide-coupled phototransistors, allowing us to detect light of 621 fW propagating in the Si waveguide. The high responsivity and the reasonable response time of approximately 100 μs make our phototransistor promising as an effective optical power monitor in Si photonic circuits.

   @article{OCHIAI_2022_NCOM,
     title = {Ultrahigh-responsivity waveguide-coupled optical power monitor for Si photonic circuits operating at near-infrared wavelengths},
     author = {Ochiai, Takaya and Akazawa, Tomohiro and Miyatake, Yuto and Sumita, Kei and Ohno, Shuhei and Monfray, St{\'e}phane and Boeuf, Frederic and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Nature Communications},
     volume = {13},
     number = {1},
     pages = {7443},
     year = {2022},
     publisher = {Nature Publishing Group UK London},
     doi = {10.1038/s41467-022-35206-4},
   }

3. ECST

   Ge-on-insulator Platform for Mid-infrared Photonic Integrated Circuits

   Mitsuru Takenaka, Ziqiang Zhao, Chong Pei Ho, and 6 more authors

   ECS Transactions, Sep 2022

   Abs DOI Bib

   

   Since mid-infrared (MIR) wavelengths have a great potential for optical communication, sensing, and quantum information, Si-based MIR photonic integrated circuits (PICs) have been developed by leveraging Si photonics technology for near-infrared wavelengths. However, the transparency wavelength window of Si is from 1.2 μm to 8 μm, limiting the available wavelengths in the MIR spectrum. Ge is emerging as a waveguide material to overcome this difficulty because Ge is transparent in the entire MIR spectrum. We have developed a Ge-on-insulator (GeOI) platform for MIR integrated photonics. The strong optical confinement in a GeOI waveguide enables an ultracompact MIR PIC. Using wafer bonding and Smart-cut, a GeOI wafer was successfully fabricated. As a result, we have demonstrated various Ge passive devices, thermo-optic phase shifters, modulators, and photodetectors on a GeOI platform.

   @article{TAKENAKA_2022_ECST,
     doi = {10.1149/10904.0047ecst},
     url = {https://doi.org/10.1149/10904.0047ecst},
     year = {2022},
     month = sep,
     publisher = {The Electrochemical Society, Inc.},
     volume = {109},
     number = {4, invited},
     pages = {47},
     author = {Takenaka, Mitsuru and Zhao, Ziqiang and Ho, Chong Pei and Fujigaki, Takumi and Piyapatarakul, Tipat and Miyatake, Yuto and Tang, Rui and Toprasertpong, Kasidit and Takagi, Shinichi},
     title = {Ge-on-insulator Platform for Mid-infrared Photonic Integrated Circuits},
     journal = {ECS Transactions},
   }

4. IEDM

   Record-low Loss Non-volatile Mid-infrared PCM Optical Phase Shifter based on Ge2 Sb2 Te3 S2

   Yuto Miyatake, Kotaro Makino, Junji Tominaga, and 6 more authors

   In 2022 International Electron Devices Meeting (IEDM), Dec 2022

   Abs DOI Bib

   

   We propose a low-loss non-volatile phase change material (PCM) phase shifter operating at mid-infrared wavelengths using Ge₂Sb₂Te₃S₂ (GSTS), a new selenium-free widegap PCM. The Si waveguide with GSTS exhibited the record-low optical loss for \pi phase shift of 0.29\textdB/\pi, more than 20 times better than the PCM phase shifters reported so far in terms of figure-of-merit, defined by ∆n/\kappa_c, where ∆n and \kappa_\textc are the change in the refractive index and the extinction coefficient of the crystalline PCM, respectively. A GSTS phase shifter, enabled by our approach to use a wider bandgap PCM at a longer operating wavelength, is one of the solutions to realize a low-loss phase shifter for quantum photonic integrated circuits.

   @inproceedings{MIYATAKE_2022_IEDM,
     author = {Miyatake, Yuto and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinich and Takenaka, Mitsuru},
     booktitle = {2022 International Electron Devices Meeting (IEDM)},
     title = {Record-low Loss Non-volatile Mid-infrared PCM Optical Phase Shifter based on Ge2 Sb2 Te3 S2},
     year = {2022},
     volume = {},
     number = {},
     pages = {19.1.1-19.1.4},
     keywords = {Phase change materials;Optical losses;Waveguide transitions;Optical recording;Phase shifters;Photonic integrated circuits;Optical variables control},
     doi = {10.1109/IEDM45625.2022.10019420},
     issn = {2156-017X},
     month = dec,
   }

5. ISPEC

   Optimization of Compact and Low-loss 2×2 Si Optical Coupler based on CMA-ES

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   In 12th International Symposium on Photonics and Electronics Convergence (ISPEC2022), Dec 2022

   Bib

   @inproceedings{MIYATAKE_2022_ISPEC,
     title = {Optimization of Compact and Low-loss 2×2 Si Optical Coupler based on CMA-ES},
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {12th International Symposium on Photonics and Electronics Convergence (ISPEC2022)},
     pages = {1--2},
     number = {P-2},
     year = {2022},
     month = dec,
   }

6. SSDM

   Compact, low-loss, fabrication-tolerant, and thermally stable 2x2 Si optical coupler designed by CMA-ES

   Yuto Miyatake, Kasidit Toprasertpong, Shinichi Takagi, and 1 more author

   In International Conference on Solid State Devices and Materials (SSDM), 2022

   Bib

   @inproceedings{MIYATAKE_2022_SSDM,
     title = {Compact, low-loss, fabrication-tolerant, and thermally stable 2x2 Si optical coupler designed by CMA-ES},
     author = {Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {International Conference on Solid State Devices and Materials (SSDM)},
     number = {A-10-04},
     pages = {1--2},
     year = {2022},
     organization = {JSAP},
   }

7. ISPEC

   Si hybrid integration using ultrathin III-V membrane for photodetection

   Mitsuru Takenaka, Takaya Ochiai, Tomohiro Akazawa, and 7 more authors

   In 12th International Symposium on Photonics and Electronics Convergence (ISPEC2022), Dec 2022

   Bib

   @inproceedings{TAKENAKA_2022_ISPEC,
     title = {Si hybrid integration using ultrathin III-V membrane for photodetection},
     author = {Takenaka, Mitsuru and Ochiai, Takaya and Akazawa, Tomohiro and Miyatake, Yuto and Sumita, Kei and Ohno, Shuhei and Monfray, Sylvain and Boeuf, Frédéric and Toprasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {12th International Symposium on Photonics and Electronics Convergence (ISPEC2022)},
     number = {D-2},
     year = {2022},
     month = dec,
   }

8. ECS

   Ge-on-insulator platform for mid-infrared photonic integrated circuits

   Mitsuru Takenaka, Ziqiang Zhao, Piyapatarakul Tipat, and 3 more authors

   In 242th ECS Meeting, Oct 2022

   Bib

   @inproceedings{TAKENAKA_2022_ECS,
     title = {Ge-on-insulator platform for mid-infrared photonic integrated circuits},
     author = {Takenaka, Mitsuru and Zhao, Ziqiang and Tipat, Piyapatarakul and Miyatake, Yuto and prasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {242th ECS Meeting},
     number = {Symposium G03, invited},
     year = {2022},
     month = oct,
   }

9. PSC

   III-V/Si hybrid integration for scalable optical switching and computing

   Mitsuru Takenaka, Hanzhi Tang, Kohei Watanabe, and 17 more authors

   In International Conference on Photonics in Switching and Computing (PSC2022), Jul 2022

   Bib

   @inproceedings{TAKENAKA_2022_PSC,
     author = {Takenaka, Mitsuru and Tang, Hanzhi and Watanabe, Kohei and Ochiai, Takaya and Akazawa, Tomohiro and Huang, Ming and Wakita, Yosuke and Miyatake, Yuto and Ohno, Shuhei and Sumita, Kei and Monfray, Sylvain and Boeuf, Frédéric and Tang, Rui and Tang, Rui and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Okano, Makoto and Toprasertpong, Kasidit and Takagi, Shinichi},
     booktitle = {International Conference on Photonics in Switching and Computing (PSC2022)},
     title = {III-V/Si hybrid integration for scalable optical switching and computing},
     year = {2022},
     volume = {},
     number = {invited},
     month = jul,
   }

10. JSAP

    CAM-ESに基づく小型低損失2×2カプラの設計

    宮武悠人, トープラサートポンカシディット, 高木信一, and 1 more author

    In 第83回応用物理学会秋季学術講演会, Sep 2022

    Bib

    @inproceedings{MIYATAKE_2022_JSAP-AUTUMN,
      author = {宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中充},
      booktitle = {第83回応用物理学会秋季学術講演会},
      title = {CAM-ESに基づく小型低損失2×2カプラの設計},
      year = {2022},
      volume = {},
      number = {21a-A205-9},
      pages = {},
      month = sep,
    }

2021

1. OME

   Low-loss Ge waveguide at the 2-µm band on an n-type Ge-on-insulator wafer

   Ziqiang Zhao, Cheol-Min Lim, Chongpei Ho, and 5 more authors

   Opt. Mater. Express, Dec 2021

   Abs DOI Bib

   

   Integrated mid-infrared (MIR) photonics has been widely investigated for the past decade, where germanium (Ge) is a promising optical material in this regime. In this work, we studied the origin of optical losses in Ge waveguides on a Ge-on-insulator (GeOI) wafer fabricated using Smart-cut. We observed that the high optical loss was mainly due to the holes in Ge films, which were generated by crystal defects formed by hydrogen ion implantation for Smart-cut. Furthermore, we found that the carrier concentration profile after the splitting process in remaining Ge films depends on the hydrogen ion implantation energy and initial background doping concentration of Ge wafers. A higher proton implantation energy can lead to deeper penetration of hydrogen ions into Ge films with less damage remaining near the implantation surface, resulting in the successful fabrication of an n-type GeOI wafer with a low carrier density. As a result, we experimentally demonstrated a low-loss Ge waveguide on an n-type GeOI wafer with a propagation loss as low as 2.3 ± 0.2 dB/cm. This work suggests an approach to tailor the carrier type in a Ge film formed using Smart-cut for large-scale MIR Ge photonic integrated circuits.

   @article{ZHAO_2021_OME,
     author = {Zhao, Ziqiang and Lim, Cheol-Min and Ho, Chongpei and Sumita, Kei and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     journal = {Opt. Mater. Express},
     keywords = {Chalcogenide glass; Frequency combs; Germanium; Hydrogen; Optical materials; Variable optical attenuators},
     number = {12},
     pages = {4097--4106},
     publisher = {Optica Publishing Group},
     title = {Low-loss Ge waveguide at the 2-\&\#x00B5;m band on an n-type Ge-on-insulator wafer},
     volume = {11},
     month = dec,
     year = {2021},
     url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-11-12-4097},
     doi = {10.1364/OME.444071},
   }

2. ISPEC

   Reduction of optical loss of phase-change phase shifter based on Ge₂Sb₂Te₅ operating at mid-infrared wavelength

   Yuto Miyatake, Chong Pei Ho, Kotaro Makino, and 7 more authors

   In 12th International Symposium on Photonics and Electronics Convergence (ISPEC2021), Dec 2021

   Bib

   @inproceedings{MIYATAKE_2021_ISPEC,
     title = {Reduction of optical loss of phase-change phase shifter based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> operating at mid-infrared wavelength},
     author = {Miyatake, Yuto and Ho, Chong Pei and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {12th International Symposium on Photonics and Electronics Convergence (ISPEC2021)},
     number = {P-22},
     year = {2021},
     month = dec,
   }

3. OFC

   Thermo-optic Mach–Zehnder Interferometer Integrated with Si PN Diode Switch for Bipolar Optical Phase Control

   Hanzhi Tang, Shuhei Ohno, Yuto Miyatake, and 3 more authors

   In Optical Fiber Communication Conference (OFC) 2021, 2021

   Abs DOI Bib

   

   We demonstrated the bipolar phase control in Mach–Zehnder interferometer by serial connection of TiN heaters and PN diodes. We achieved 2\pi phase shift with single electrical signal, and pulse amplitude modulation for time-multiplexed control.

   @inproceedings{TANG_2021_OFC,
     author = {Tang, Hanzhi and Ohno, Shuhei and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {Optical Fiber Communication Conference (OFC) 2021},
     journal = {Optical Fiber Communication Conference (OFC) 2021},
     keywords = {Interferometers; Optical computing; Optical neural systems; Phase modulation; Phase shift; Silicon photonics},
     pages = {Tu5B.5},
     publisher = {Optica Publishing Group},
     title = {Thermo-optic Mach--Zehnder Interferometer Integrated with Si PN Diode Switch for Bipolar Optical Phase Control},
     year = {2021},
     url = {https://opg.optica.org/abstract.cfm?URI=OFC-2021-Tu5B.5},
     doi = {10.1364/OFC.2021.Tu5B.5},
   }

4. JSAP

   Siストリップ導波路を用いた非対称方向性結合器による波長依存性低減の検討

   宮武悠人, トープラサートポンカシディット, 高木信一, and 1 more author

   In 第82回応用物理学会秋季学術講演会, Sep 2021

   Bib

   @inproceedings{MIYATAKE_2021_JSAP-AUTUMN,
     author = {宮武悠人 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {第82回応用物理学会秋季学術講演会},
     title = {Siストリップ導波路を用いた非対称方向性結合器による波長依存性低減の検討},
     year = {2021},
     volume = {},
     number = {11a-N207-3},
     pages = {},
     month = sep,
   }

5. JSAP

   波長2.4umで動作する相変化材料を用いた中赤外光位相シフタ

   宮武悠人, 牧野孝太郎, 富永淳二, and 6 more authors

   In 第68回応用物理学会春季学術講演会, Mar 2021

   Bib

   @inproceedings{MIYATAKE_2021_JSAP-SPRING,
     author = {宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 関根尚希 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {第68回応用物理学会春季学術講演会},
     title = {波長2.4umで動作する相変化材料を用いた中赤外光位相シフタ},
     year = {2021},
     volume = {},
     number = {17a-Z10-8},
     pages = {},
     month = mar,
   }

6. JSAP

   シリコンプログラマブル光回路を用いた深層学習の展望

   竹中充, 湯涵智, 大野修平, and 4 more authors

   In 第68回応用物理学会春季学術講演会, Mar 2021

   Bib

   @inproceedings{TAKENAKA_2021_JSAP-SPRING,
     author = {竹中充 and 湯涵智 and 大野修平 and 宮武悠人 and 渡辺耕坪 and トープラサートポンカシディット and 高木信一},
     booktitle = {第68回応用物理学会春季学術講演会},
     title = {シリコンプログラマブル光回路を用いた深層学習の展望},
     year = {2021},
     volume = {},
     number = {17p-Z08-7, 招待講演},
     pages = {},
     month = mar,
   }

7. JSAP

   Bipolar thermo-optic Mach–Zehnder interferometer with pulse-height modulation

   Hanzhi Tang, Shuhei Ohno, Yuto Miyatake, and 3 more authors

   In 第68回応用物理学会春季学術講演会, Mar 2021

   Bib

   @inproceedings{TANG_2021_JSAP-SPRING,
     author = {Tang, Hanzhi and Ohno, Shuhei and Miyatake, Yuto and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {第68回応用物理学会春季学術講演会},
     title = {Bipolar thermo-optic Mach–Zehnder interferometer with pulse-height modulation},
     year = {2021},
     volume = {},
     number = {18a-Z18-3},
     pages = {},
     month = mar,
   }

2020

1. JJAP

   

   Computational design of efficient grating couplers using artificial intelligence

   Yuto Miyatake, Naoki Sekine, Kasidit Toprasertpong, and 2 more authors

   Japanese Journal of Applied Physics, Mar 2020

   Abs DOI Bib

   

   We examined the applicability of neural networks (NNs) and the covariance matrix adaptation evolution strategy (CMA-ES) for designing high-efficiency grating couplers on a Si-on-insulator (SOI) photonics platform operating at a wavelength of 1550 nm. We trained a NN to predict the wavelength dependences of coupling efficiency instead of using the finite-difference time-domain method, which enabled us to calculate analytically the gradient of coupling efficiency with respect to the design parameters. As a result, we found that a gradient-based method can be applied to find a more optimal design from an apodized grating coupler. In contrast, the CMA-ES, which is one of the most efficient evolutionary strategies, enabled us to explore a large design-parameter space efficiently without any constraint in an initial design of a grating coupler. As a result, we successfully obtained the optimal design from a uniform grating coupler. The optimized grating coupler exhibited a coupling efficiency of 74.7% when the thickness of the Si layer is 220 nm. The CMA-ES also enabled us to optimize the thickness of the Si gratings simultaneously. Through the optimization, we achieved a coupling efficiency of 92.1% when the Si thickness is 293 nm.

   @article{MIYATAKE_2020_JJAP,
     doi = {10.7567/1347-4065/ab641c},
     url = {https://doi.org/10.7567/1347-4065/ab641c},
     year = {2020},
     month = mar,
     publisher = {IOP Publishing},
     volume = {59},
     number = {SG},
     pages = {SGGE09},
     author = {Miyatake, Yuto and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     title = {Computational design of efficient grating couplers using artificial intelligence},
     journal = {Japanese Journal of Applied Physics},
   }

2. ECOC

   Mid-infrared Non-volatile Compact Optical Phase Shifter Based on Ge₂Sb₂Te₅

   Yuto Miyatake, Chong Pei Ho, Prakash Pitchappa, and 9 more authors

   In 2020 European Conference on Optical Communications (ECOC), 2020

   Bib

   

   @inproceedings{MIYATAKE_2020_ECOC,
     title = {Mid-infrared Non-volatile Compact Optical Phase Shifter Based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>},
     author = {Miyatake, Yuto and Ho, Chong Pei and Pitchappa, Prakash and Singh, Ranjan and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {2020 European Conference on Optical Communications (ECOC)},
     pages = {1--4},
     year = {2020},
     organization = {IEEE},
   }

3. ISPEC

   Non-volatile compact optical phase shifter based on Ge₂Sb₂Te₅ operating at mid-infrared wavelength

   Yuto Miyatake, Chong Pei Ho, Prakash Pitchappa, and 9 more authors

   In 12th International Symposium on Photonics and Electronics Convergence (ISPEC2020), Nov 2020

   Bib

   @inproceedings{MIYATAKE_2020_ISPEC,
     title = {Non-volatile compact optical phase shifter based on Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> operating at mid-infrared wavelength},
     author = {Miyatake, Yuto and Ho, Chong Pei and Pitchappa, Prakash and Singh, Ranjan and Makino, Kotaro and Tominaga, Junji and Miyata, Noriyuki and Nakano, Takashi and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {12th International Symposium on Photonics and Electronics Convergence (ISPEC2020)},
     number = {S-5},
     year = {2020},
     month = nov,
   }

4. NOLTA

   CMOS-compatible physical reservoir computing using ferroelectric field-effect transistors

   Kasidit Toprasertpong, Eishin Nako, Zeyu Nakane, and 4 more authors

   In International Symposium on Nonlinear Theory and Its Applications (NOLTA2020), Nov 2020

   Bib

   @inproceedings{TOPRASERTPONG_2020_NOLTA,
     author = {Toprasertpong, Kasidit and Nako, Eishin and Nakane, Ryosho Wang, Zeyu and Miyatake, Yuto and Takenaka, Mitsuru and Takagi, Shinichi and Wang, Zeyu},
     booktitle = {International Symposium on Nonlinear Theory and Its Applications (NOLTA2020)},
     title = {CMOS-compatible physical reservoir computing using ferroelectric field-effect transistors},
     year = {2020},
     volume = {},
     number = {invited},
     month = nov,
   }

5. VLSI

   Proposal and Experimental Demonstration of Reservoir Computing using Hf_0.5Zr_0.5O₂/Si FeFETs for Neuromorphic Applications

   E. Nako, K. Toprasertpong, R. Nakane, and 4 more authors

   In 2020 IEEE Symposium on VLSI Technology, Jun 2020

   Abs DOI Bib

   

   We propose a new AI calculation scheme by reservoir computing utilizing the memory effect and non-linearity of ferroelectric gate MOSFETs (FeFETs) for neuromorphic applications. The task operations of time-series data are experimentally demonstrated by taking time responses of the drain current for gate voltage input as the virtual nodes. A high ability to classify input data is experimentally verified.

   @inproceedings{NAKO_2020_VLSI,
     author = {Nako, E. and Toprasertpong, K. and Nakane, R. and Wang, Z. and Miyatake, Y. and Takenaka, M. and Takagi, S.},
     booktitle = {2020 IEEE Symposium on VLSI Technology},
     title = {Proposal and Experimental Demonstration of Reservoir Computing using Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/Si FeFETs for Neuromorphic Applications},
     year = {2020},
     volume = {},
     number = {},
     pages = {1-2},
     keywords = {Reservoirs;Delays;Task analysis;Silicon;Logic gates;MOSFET;Voltage measurement},
     doi = {10.1109/VLSITechnology18217.2020.9265110},
     issn = {2158-9682},
     month = jun,
   }

6. JSAP

   相変化材料を用いた中赤外光位相シフタの提案

   宮武悠人, 牧野孝太郎, 富永淳二, and 6 more authors

   In 第81回応用物理学会秋季学術講演会, Sep 2020

   Bib

   @inproceedings{MIYATAKE_2020_JSAP-AUTUMN,
     author = {宮武悠人 and 牧野孝太郎 and 富永淳二 and 宮田典幸 and 中野隆志 and 関根尚希 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {第81回応用物理学会秋季学術講演会},
     title = {相変化材料を用いた中赤外光位相シフタの提案},
     year = {2020},
     volume = {},
     number = {9p-Z19-8},
     pages = {},
     month = sep,
   }

7. JSAP

   進化戦略で設計した高効率グレーティングカプラの作製

   宮武悠人, 関根尚希, トープラサートポンカシディット, and 2 more authors

   In 第67回応用物理学会春季学術講演会, Mar 2020

   Bib

   @inproceedings{MIYATAKE_2020_JSAP-SPRING,
     author = {宮武悠人 and 関根尚希 and トープラサートポンカシディット and 高木信一 and 竹中充},
     booktitle = {第67回応用物理学会春季学術講演会},
     title = {進化戦略で設計した高効率グレーティングカプラの作製},
     year = {2020},
     volume = {},
     number = {14p-B508-4},
     pages = {},
     month = mar,
   }

8. JSAP

   FeFETリザバーコンピューティングにおける動作電圧と性能の関係の検証

   名幸瑛心, トープラサートポン・カシディット, 王澤宇, and 4 more authors

   In 第81回応用物理学会秋季学術講演会, Sep 2020

   Bib

   @inproceedings{NAKO_2020_JSAP-AUTUMN,
     author = {名幸瑛心 and トープラサートポン・カシディット and 王澤宇 and 中根了昌 and 宮武悠人 and 竹中充 and 高木信一},
     booktitle = {第81回応用物理学会秋季学術講演会},
     title = {FeFETリザバーコンピューティングにおける動作電圧と性能の関係の検証},
     year = {2020},
     volume = {},
     number = {9p-Z28-7},
     pages = {},
     month = sep,
   }

9. IEICE

   ニューロモルフィック応用に向けた Hf_0.5Zr_0.5O₂/Si FeFET を用いたリザバーコンピューティング

   名幸瑛心, トープラサートポン・カシディット, 中根了昌, and 4 more authors

   In 電子情報通信学会SDM研究会, Aug 2020

   Bib

   @inproceedings{NAKO_2020_IEICE,
     author = {名幸瑛心 and トープラサートポン・カシディット and 中根了昌 and 王澤宇 and 宮武悠人 and 竹中充 and 高木信一},
     booktitle = {電子情報通信学会SDM研究会},
     title = {ニューロモルフィック応用に向けた Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/Si FeFET を用いたリザバーコンピューティング},
     year = {2020},
     volume = {},
     number = {招待講演},
     pages = {},
     month = aug,
   }

10. JSAP

    FeFETリザバーコンピューティングにおける強誘電性の効果の検証

    名幸瑛心, トープラサートポン・カシディット, 中根了昌, and 4 more authors

    In 第67回応用物理学会春季学術講演会, Sep 2020

    Bib

    @inproceedings{NAKO_2020_JSAP-SPRING,
      author = {名幸瑛心 and トープラサートポン・カシディット and 中根了昌 and 王澤宇 and 宮武悠人 and 竹中充 and 高木信一},
      booktitle = {第67回応用物理学会春季学術講演会},
      title = {FeFETリザバーコンピューティングにおける強誘電性の効果の検証},
      year = {2020},
      volume = {},
      number = {14a-A301-3},
      pages = {},
      month = sep,
    }

2019

1. SSDM

   Computational design of high-efficiency grating coupler based on deep learning

   Yuto Miyatake, Naoki Sekine, Kasidit Toprasertpong, and 2 more authors

   In International Conference on Solid State Devices and Materials (SSDM), 2019

   Bib

   @inproceedings{MIYATAKE_2019_SSDM,
     title = {Computational design of high-efficiency grating coupler based on deep learning},
     author = {Miyatake, Yuto and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {International Conference on Solid State Devices and Materials (SSDM)},
     number = {B-2-05},
     pages = {1--2},
     year = {2019},
     organization = {JSAP},
   }

2. ISPEC

   “Optimization of grating couplers on SOI using artificial intelligence

   Yuto Miyatake, Naoki Sekine, Kasidit Toprasertpong, and 2 more authors

   In 12th International Symposium on Photonics and Electronics Convergence (ISPEC2019), Nov 2019

   Bib

   @inproceedings{MIYATAKE_2019_ISPEC,
     title = {“Optimization of grating couplers on SOI using artificial intelligence},
     author = {Miyatake, Yuto and Sekine, Naoki and Toprasertpong, Kasidit and Takagi, Shinichi and Takenaka, Mitsuru},
     booktitle = {12th International Symposium on Photonics and Electronics Convergence (ISPEC2019)},
     number = {S-5},
     year = {2019},
     month = nov,
   }

3. JSAP

   強誘電体FETを用いたリザバーコンピューティングの実験的検証

   名幸瑛心, トープラサートポン・カシディット, 中根了昌, and 4 more authors

   In 第80回応用物理学会秋季学術講演会, Sep 2019

   Bib

   @inproceedings{NAKO_2019_JSAP-AUTUMN,
     author = {名幸瑛心 and トープラサートポン・カシディット and 中根了昌 and 王澤宇 and 宮武悠人 and 竹中充 and 高木信一},
     booktitle = {第80回応用物理学会秋季学術講演会},
     title = {強誘電体FETを用いたリザバーコンピューティングの実験的検証},
     year = {2019},
     volume = {},
     number = {19p-F211-5},
     pages = {},
     month = sep,
   }