Observation of Dynamic Frequency Chirp in Bistable Semiconductor Laser Amplifiers

Dispersive optical bistability in a Fabry-Perot, a distributed feedback (DFB), or a distributed Bragg reflector (DBR), semiconductor laser amplifier has recently attracted much attention, because of its potential in the operation of highly functional optical devices. While the steady-state operation of bistable diode laser amplifiers are well understood, studies of the dynamic properties have been limited to switching time, critical slowing down and output spiking measurements[1-3]. Little attention has been paid to the dynamic frequency chirp which is associated with the turn-on spike at the onset of light injection. Such frequency chirp exists because in dispersive bistability the Fabry-Perot resonance (or the DBR/DFB transmission peak) sweeps through the injected wavelength as a result of alight induced refractive index change. In this paper, we report on a theoretical analysis and the first experimental observation of this dynamic chirp in a Fabry-Perot type nonlinear semiconductor laser amplifier. It is found that the magnitude of the chirp depends on the input power, which in turn is related to critical slowing down.