A novel 1 x 4 coupler-multiplexer permutation switch for WDM applications

A novel 1 x 4 coupler multiplexer permutation switch (CMPS) is proposed for applications in wavelength-division-multiplexing (WDM) optical networks. T he structure of the CMPS integrates the multiplexing and switching function s into a single compact device. It consists of a single-mode/multimode-wave guide grating-assisted, backward-coupler multiplexer followed by a 1 x 4 di gital optical switch (DOS), The specific design uses an InP-based 1 x 4 CMP S with InGaAsP/InP multiple-quantum-well (MQW) DOS. The calculated values o f crosstalk for the coupler multiplexer and the DOS are <-25 dB and -23 dB, respectively, giving an overall crosstalk <-21 dB for channel bandwidths o f 10-13 GHz, The device channels are unequally spaced, which reduces unwant ed four-wave mixing (FWM), but are fitted to the ITU standard wavelength gr id.