Multi-order optical cross-connect

Abstract

A selective routing cross-connect device comprises a switch array, together with a phasar. The phasar comprises an array of channel waveguides, and first and second slab waveguides. A main input feeds a wavelength division multiplexed (WDM) signal into the first slab waveguide so that demultiplexed outputs corresponding to an m diffraction order exit the second slab waveguide. First and second further waveguides feed respective sets of demultiplexed signals back into the second slab waveguide at positions offset from said m diffraction order (preferably at locations slightly offset from the adjacent diffraction orders). The first further waveguide supplies those demultiplexed signals which are to remain in the main channel, together with any added signals, whereas the third waveguide supplies those demultiplexed signals which are to be dropped. Selection of component signals for maintenance, adding or dropping is performed by control of the switch array. The added demultiplexed signals can be generated by inputting a WDM add channel to the second slab waveguide at a free location (preferably offset from the m diffraction order by two times the adjacent channel spacing), and looping back to the switch array the resultant demultiplexed outputs which exit the first slab waveguide.