Free space photonic switching network demonstration

A prototype digital free-space photonic switching fabric consisting of three cascaded 16*8 arrays of symmetric self-electrooptic effect devices (S-SEEDs) is demonstrated. The three stages implement the input interface and one 2*1 node stage of a multistage switching network using crossover interconnections. The devices in the arrays used in this experiment are configured to function as logic gates to implement an array of 2*1 switching nodes. The 128 data inputs to the system are generated by a matrix of 64 fibers and by a laser passing through 8*8 binary phase grating (BPG) beamsplitter. The output power from each fiber is 94 mu W. Vignetting in the collection optics results in an output power of less than 1 mu W, which limits the first stage switching speed to about 100 kHz (33-kb/s system data rate). The minimum signal power cascaded from one S-SEED array to the next is about 150 mu W. If the system speed were limited only by the signal powers between arrays, a data rate of 200 kb/s would be achievable.<>