Bidirectional Optical Fiber Transmission using a Multiple Quantum Well (MQW) Modulator/Detector

Abstract

For many short-distance communication applications in the telephone loop plant or local area networks where cost is a significant factor, use of a traditional bidirectional optical fiber communications system with 2 lasers, 2 fibers, and 2 detectors is unattractive. Additionally, such traditional systems require the placement of a laser at the user site, where an environment hostile to the laser might be encountered. These considerations have led to interest in nontraditional system architectures which require fewer components.[1] One approach which has been demonstrated is the use of a single fiber connecting the two users, with a laser at one end, and a photodetector and lithium niobate waveguide modulator at the other.[2] In this system, which operated at a wavelength of 1.3 μm, a portion of the light emerging from the optical fiber is passed through the modulator, returned to the fiber, and detected at the laser location. Data rates of 34 Mbit/sec and 565 Mbit/sec were achieved over a 2 km span in the modulator-to-laser and laser-to-detector directions, respectively.