High performance optical wavelength multiplexer–demultiplexer

Abstract
The principle of an optical wavelength multiplexer–demultiplexer is described in which the signals undergo repeated reflections from special filter elements that can be designed for a wide range of cross-talk ratios. The insertion losses of these units can be quite small and they can be implemented to provide simultaneous multichannel two-way transmission. In a preliminary investigation of an experimental prototype an insertion loss of 0.5 dB and a cross talk of −35 dB were demonstrated. The multiplexer–demultiplexer is expected to have a long life and high reliability.