A Free Space Optical Data Link using GaAs Multiple Quantum Well Modulators and Si CMOS Photodetectors.

We report the operation of a simple optical link using two GaAs Multiple Quantum Well Modulators (MQWMs) as the output port, a differential photodetector and sense circuit fabricated using Si CMOS technology as the input port and free space optics for the interconnect. The GaAs MQWMs could be modulated at over 1GHz. The differential photodetectors circuit could be operated at over 150MHz with ~ 100microwatts incident optical power. The operating speed of the system was limited by saturation of the MQWMs, unoptimized optical coatings, and unoptimized photodetectors to 10MHz with incident powers on the MQWMs of 90microwatts. The experiment does however serve as proof of principle for the development of fully integrated optical interchip communication.