OPTICAL SWITCH

摘要

Optical signals used for telecommunications in time division multiplexed format are processed to remove channels for local demodulation and to replac e the removed channels with locally modulated data. The received signals (15) are subjected to a further wavelength modulation (13) so that signals in selected channels are given distinctive wavelengths. After wavelength modulation the time division multiplexed signals are separated using wavelength sensitive splitters (21, 24) and the various channels are sent their correct destinations by wavelength selection. In a preferred embodimen t one channel is selected and given a distinctive wavelength and all the non- selected channels retain their original wavelength. The channels with the original wavelength are provided to an output terminal (25) for onward transmission whereas the selected channel is provided (26) for local demodulation. The invention is particularly suitable for use with signals within a bit interleaved version of a time division multiplex.