Ultrafast all-optical switching of bistable Semiconductor Ring Lasers

Semiconductor ring lasers (SRLs) usually exhibit regimes of unidirectional operation, which offers a great potential for applications such as all-optical memories, switching and gating. In this paper, bistable semiconductor ring lasers of cavity lengths ranging from 1200 ¿m up to 1900 ¿m is fabricated. The devices were fabricated on a multiple quantum well AlGalnAs/InP wafer using a shallow etched technology. To study all-optical flip-flop operation of the device, 5 ps FWHM optical trigger pulses produced by an OPO is injected. In order to evaluate the limits of switching speed that can be achieved, numerical simulations of the SRL using a recently developed traveling-wave model is performed. The model includes coupling of the CW and CCW waves arising from both spectral- and spatial-hole burning in the carrier density. The numerical results are in excellent agreement with the experimental observations.