Interfacing Massively Parallel Computers to Terabit Fiber Links

摘要

This program investigated the potential use of refractive index modulation in III-V semiconductor multiple quantum wells of interfacing electronic parallel computers and/or local networks to terabit fiber links. The lack of efficient and fast optoelectronic devices capable of modulating large optical intensities inhibits such interfaces. Traditionally, multiple-quantum- well (MQW) devices have been limited to the use of amplitude modulation at low optical intensity. Although the index modulation in MQW material is potentially higher than in other electro-optical materials, this effect is masked by the absorption leading to phase modulated devices with very high insertion loss. Thus the main thrust of this program was to study the refractive index modulation in III-V semiconductor MQW devices under high optical power. We have showed theoretically and experimentally during the course of this program, that the refractive index modulation in MQW materials although small in magnitude also exists above absorption saturation. This finding indicates the potential use of MQW material for phase modulation with low insertion loss when biased properly. A phase-shift interferometry method has been developed to measure the index change with a resolution of 1/2500. The measured index change in our MQW materials under intensity saturation was about 0.05% for a modulation voltage of 3V.