Packet Networks using All-Optical Bit Serial Processing

In the early days of computing (1940’s and 1950’s), computers were designed to operate serially as no static memory was available and storage could only be implemented using recirculating delay lines. Modem silicon based computers process data in parallel using static memory and latching logic gates. If processing is to be possible in all-optical form we believe it is necessary to return to serial techniques since it has proved difficult to keep light still and obtain latching. Recent work at Colorado [1] has used these serial techniques to implement a stored program optoelectronic computer using a combination of electronic detection to control lithium niobate gates and optical fibres to provide the optical pathways. The key feature of the bit serial design is to use the time of flight of the light to provide a natural memory and to arrange for computation to occur by appropriate synchronisation of data and control pulses. One advantage of this approach is that the optical processing is scaleable in bit rate. In this paper we will describe an all-optical implementation of these techniques, based on the Nonlinear Optical Loop Mirror (NOLM)[2] switch architecture, with application to the operation of packet switched networks.