Multimode interference bistable laser diode

We propose a novel bistable laser diode (BLD) with active multimode interference (MMI) cavity. Bistable switching can be realized between two cross-coupled modes by means of gain saturation. Static characteristics of the multimode interference (MMI)-BLD are analyzed using a finite-difference beam propagation method. The photon-carrier interactions are calculated using the carrier-rate equation. This model gives accurate distributions of photon and carrier densities, optical gain, and refractive index inside the cavity. We predict that the MMI-BLD shows bistable switching between the two cross-coupled modes by light injection, therefore allowing it to be used as all-optical flip-flop or optical memory.