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. 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. 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.
© 1986 Optical Society of AmericaPDF Article