Bistable output characteristics in semiconductor laser injection locking

Experimental observations of bistability in semiconductor lsaer injection locking are demonstrated for the first time in the output versus frequency detuning curve. This is accomplished using DFB lasers for both injecting and injected lasers in order to maintain a single longitudinal mode operation, even at a near laser threshold. The essential mechanism giving rise to the bistability is the carrier density dependence of the refractive index in the active region. Bistability in injected laser output is also observed when the injecting laser drive current changes.