Semiconductor laser amplifier in loop mirror configurations for signal-processing

The authors discuss the SLALOM (SLA in a Loop Mirror) and the TOAD (Terahertz Optical Asymmetric Demultiplexer). The TOAD appears to be a modification of the SLALOM. They show that based on the SLALOM several functions are possible which are required to make an all-optical system. Examples described are: demultiplexer, decision gate for data regeneration, and noise suppression in a fiber ring optical buffer. The properties of the SLALOM depend not on the fiber nonlinearity but on the nonlinearity of the SLA together with the interferometer operation of the fiber loop. Consequently, the SLALOM is different from the nonlinear fiber loop mirror even if sometimes optical amplifiers are used in these loop mirrors. Because the nonlinear effect in the SLALOM is confined to a length of some 100 mu m, the SLALOM can be very compact and an integration of the SLALOM (SLA, coupler and waveguide) on a chip seems to be possible. In most of the applications the operation speed of the SLALOM appears to be limited by the gain recovery time of the SLA to a few GHz. An exception is the application to the multiplexer/demultiplexer, where an operation speed up to 100 GHz is predicted.