Tatsuro Hiraki

Silicon/silica-hybrid delay line interferometer for DPSK demodulation

A 1-bit delay line interferometer based on silicon/silica-hybrid waveguides is demonstrated for a differential phase-shift keying (DPSK) demodulator. A 10-Gb/s NRZ-DPSK signal is demodulated with error-free operation in telecommunications bands.

Opto-electronic hybrid integrated chip packaging technology for silicon photonic platform using gold-stud bump bonding

We propose a new solder-free and low-temperature (200 °C or less) flip-chip integration technology for silicon photonic platforms. Au stud bumps are arranged facing each other on a substrate and a chip. Plastic deformation when the bumps are heated and pressed achieves Au-Au bonding. We measured mechanical and electrical characteristics (bonding strength, electrical resistance, and high-frequency characteristics) of test samples fabricated by using this technology and confirmed good performance. Further, we fabricated a four-channel WDM receiver using this technology and confirmed its good performance at 25-Gbit/s operation.

Design technique with equivalent circuit for photonics-electoronics convergence system

We developed a design technique for a photonics-electronics convergence system using an equivalent circuit of optical devices. This technique enables overall design and optimization of the photonics-electronics convergence system in an electrical circuit simulator.

22-Gbit/s × 16-ch WDM receiver based on a Si-Ge-silica monolithic photonic platform and its application to 40-km transmission

We developed a 22-Gbit/s × 16-ch WDM receiver based on a Si-Ge-silica monolithic photonic integration technology, in which a 16-ch SiOx AWG with 1.6-nm channel separation and Ge photodiodes are monolithically integrated. The AWG-PD device exhibited fiber-to-PD resoponsivity of 0.29 A/W and inter-channel crosstalk of less than 20 dB, and successfully received 22 Gbit/s signal for all 16 channels. In addition, we demonstrated 40-km transmission of 12.5 Gbit/s signal and obtained sensitivity of -6.8 dBm at BER of 10-9 without transimpedance amplifiers.