Abstract: Pseudorandom pulse code generators utilize XOR gates constructed of a pair of back to back parallel connected laser diodes, and fiber optic delay lines connecting the XOR gates to generate PN code sequences with tens of Gbits/s data rates. The single tap generator uses a fiber optic line of a length representing a selected number of delay stages connected to the optical output of the XOR gate and with optical splitters at the end of the delay line and at a selected delay stage feeding back optical signals to the optical inputs of the XOR gate to produce the PN sequence at the end of the delay line. Multi-tap generators utilize additional electro-optical XOR gates connected in serial-parallel, or preferably in a converging cascade arrangement to feed back pulses to the delay line.