WAVELENGTH-SHIFTING MODULE FOR FIBRE OPTIC ACCESS COMMUNICATIONS AND OTHER USES

摘要

The invention relates to a wavelength-shifting module for fibre optic access communications and other uses. According to the invention, the wavelength is shifted, remodulated and retransmitted to the central office using the same fibre optic. The module comprises an electro-optical modulator excited with a radio frequency tone which produces a combined amplitude and phase modulation, such that the output optical frequency is the input optical frequency moved to a value equal to the radio frequency tone. The new light is remodulated with the return data, reflected and retransmitted using the same fibre optic. Interference between signals in the opposing transmission directions of the fibre in wavelength multiplexing access network is reduced with centralised generation of optical signals and using laser-free reflexive subscriber equipment. In addition, in tuable lasers the basic version of the module can be used to obtain ultra-fine tuning.