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en: Terahertz wireless communication in a 560-GHz band using a Kerr micro-resonator soliton comb

en: Optics Continuum

ja: Optics Continuum


en: High-performance Ge/Si electro-absorption optical modulator up to 85°C and its highly efficient photodetector operation

en: We studied a high-speed Ge/Si electro-absorption optical modulator (EAM) evanescently coupled with a Si waveguide of a lateral p-n junction for a high-bandwidth optical interconnect over a wide range of temperatures from 25 °C to 85 °C. We demonstrated 56 Gbps high-speed operation at temperatures up to 85 °C. From the photoluminescence spectra, we confirmed that the bandgap energy dependence on temperature is relatively small, which is consistent with the shift in the operation wavelengths with increasing temperature for a Ge/Si EAM. We also demonstrated that the same device operates as a high-speed and high-efficiency Ge photodetector with the Franz-Keldysh (F-K) and avalanche-multiplication effects. These results demonstrate that the Ge/Si stacked structure is promising for both high-performance optical modulators and photodetectors integrated on Si platforms.

en: Optics Express

ja: Optics Express


en: Direct Bandgap Control by Narrowing the Germanium Strip Structure on Silicon for C+L Band Photonic Devices

en: IEEE Journal of Quantum Electronics

ja: IEEE Journal of Quantum Electronics


en: Si Photonic-Integrated Chip Assembly With Waveguide Ge Avalanche Photodiode for 10 Gbps L-Band Optical Access Networks

en: IEEE Photonics Journal

ja: IEEE Photonics Journal


en: High-extinction-ratio Si optical modulator loaded with integrated polarizer

en: Japanese Journal of Applied Physics

ja: Japanese Journal of Applied Physics


en: Modulation bandwidth improvement of III-V/Si hybrid MOS optical modulator by reducing parasitic capacitance

en: In this work, we numerically and experimentally examined the impact of parasitic capacitance on the modulation bandwidth of a III-V/Si hybrid metal-oxide-semiconductor (MOS) optical modulator. The numerical analysis revealed that the parasitic capacitance between the III-V membrane and the Si slab should be considered to achieve high-speed modulation, particularly in the case of a thick gate oxide. We also fabricated a high-speed InGaAsP/Si hybrid MOS optical modulator with a low capacitance using a SiO-embedded Si waveguide. The fabricated device exhibited a modulation efficiency of 0.245 Vcm and a 3 dB bandwidth of up to 10 GHz. Clear eye patterns with 25 Gbps non-return-to-zero (NRZ) modulation and 40 Gbps 4-level pulse amplitude modulation (PAM-4) were obtained without pre-emphasis.


en: Rongyang Xu, Junichi Fujikata, and Junichi Takahara, "Graphene perfect absorber based on degenerate critical coupling of toroidal mode," Opt. Lett. 48, 1490-1493 (2023)

en: Optics Letters

ja: Optics Letters


en: 112 Gb/s PAM-4 Silicon Photonics Receiver Integrated with SiGe-BiCMOS Linear TIA

en: IEEE Photonics Technology Letters

ja: IEEE Photonics Technology Letters