All-optical parity checker with bit-differential delay

We demonstrate an all-optical digital processing circuit that can check the parity of a binary optical word. The circuit operates by repetitively inpu tting the binary word to be checked into an optical memory whose capacity d iffers from the repeat time of the input word by one bit. The accumulated p arity of the input word is generated by applying the XOR logical function t o the repeated input word and the time-shifted stored word in the memory. ( C) 1999 Elsevier Science B.V. All rights reserved.