Multiplexing and Filtering of Optical Signals.

摘要

The objective of this contract is to develop an optical multiplexing device to combine onto one channel the information carried on several separate fiber optic channels and, subsequently, to perform the demultiplexing operation after transmission over distances of the order of a km. The main research effort is the development of the optical multiplexing/demultiplexing device. This device must be compatible with multimode fibers of relatively large numerical aperture, exhibit total throughput losses less than 15 dB, total signal to crosstalk ratio of more than 20 dB, and a bandwidth capability of 1.3 MHz. This report covers the work performed during a one year effort beginning May, 1976. During the past year a complete multiplexed optical data link that meets nearly all of the criteria outlined above has been constructed and tested. The main effort centered on the development of the actual electro-optic multiplexing device itself, a thin crystal of LiTaO3 that controls the flow of light with the application of appropriate voltages. Several designs were constructed and tested before the final design was chosen. The final multiplexer design exhibited less than 15 db throughput loss, and operates at high frequency with up to .25 numerical aperture fibers. The inherent signal to crosstalk ratio is about 15 dB, 5 dB less than the requested performance. Following the construction of the devices, permanent fiber-to-device connections were developed, and the complete multiplexer and demultiplexer units were packaged with integral butt coupled fibers. This is the first reported development of an optical switch with fibers produced as a permanent package.