All-optical switching behaviors in an all-semiconductor nonlinear loop device

Feasibility of pulsed-signal operation of all-optical self-switching and cross switching in an all-semiconductor optical-amplifier nonlinear optical loop device is reported. The device, based on a GaAs/AlGaAs quantum-well epitaxial structure, has dimensions of 0.6mm x 1.3mm and a latency of 49.2 ps. It is composed of a loop amplifier, a multimode interference waveguide amplifier (MMIWA), an input leg, and an output leg. The functions of the MMIWA include input/output power splitting and nonlinear coupling. Those of the loop include signal amplification, rearrangement of the field distribution in the MMIWA, and asymmetric gain/phase modulation between the two counterpropagating signals. With these functions combined, quite efficient power-dependent switching was implemented. Numerical-simulation results agreed well in trends with experimental data. From the results of output pulse width and the pump-probe measurements, it is expected that highspeed operation of the device for all-optical modulation and multiplexing/demultiplexing is feasible. (C) 2001 Optical Society of America.