Interposers for inter-chip interconnects should perform stably under high-temperature conditions and rapid temperature change due to the heat generated by mounted large-scale integration (LSI) chips. Athermal silicon optical interposers integrated with quantum dot lasers and other temperature-insensitive components on a single silicon substrate are demonstrated, and error-free data links at 12.5 Gbit/s operating from 25 to 125 degrees C are achieved without any bias adjustment. Since maximum junction temperatures in most LSIs have been below 125 degrees C now and will be in the future, the interposers are tolerant of heat generated by LSIs, and are suitable for inter-chip interconnects.

We developed a 25-Gb/s silicon modulator with 9.83-dB.V alpha V L-pi, which is smallest of those operated at 25 Gb/s and higher. We used forward-biased diode operations, which enables small V L-pi with moderately doped low-loss waveguides.

We fabricated 25-Gb/s silicon modulators with side-wall gratings on a 300-mm wafer. They exhibited high modulation efficiency of VπL = 0.274 V-cm at 12.5 GHz in forward-biased mode. Equivalent-circuit parameters showed good in-wafer uniformity for stable frequency-compensated operations.

Silicon optical interposers for inter-chip interconnects, integrated with lasers, optical splitters, modulators, waveguides and photodetectors on a single silicon substrate were demonstrated. They were optically complete and closed systems. We achieved 20-Gbps error-free data transmission and a 30-Tbps/cm2 bandwidth density using these interposers.

We developed a high-speed Mach-Zehnder modulator with the shortest phase shifter (100-μm length) reported so far. Our modulator exhibited 25-Gbps eye-openings with an extinction ratio of 4.3 dB and on-chip insertion loss of 4.7 dB.