Optical multiplexers and demultiplexers for optical wavelength-division multiplex transmission systems

Compact micro-optic multi-demultiplexers designed on the beam splitter principle were developed for optical wavelength division multiplex transmission systems with two or three wavelength channels over multimode graded index fibers. No lenses are required. The edge interference filter for separation or combination of the radiation of two different wavelengths or wavelength groups is directly evaporated onto a glass fiber endface, polished at an oblique angle. Since all ports have identical fibers, the multi/demultiplexers are used for both one way and two way communications. The components (all with fiber pigtails) were tested with light emitting diodes at wavelengths of 755, 825, and 1270 nm. The characteristic data of the 2 channel (3 channel) component vary between 1 and 2 dB (1.2 and 1.8 dB) for insertion loss, 11 and 14 dB (11 and 28 dB) for far end crosstalk attenuation and 40 dB (35 dB) for near end crosstalk attenuation.