Theory of large-signal direct modulation of extended cavitysemiconductor lasers with dispersive loss

摘要

We present a model of coupled semiconductor diode-dispersivenextended cavity lasers that describes arbitrarily large currentnmodulation, does not assume uniform photon and carrier densities withinnthe semiconductor diode gain medium, and is simple to implementnnumerically. In particular, we look at the fiber grating laser, annexample of such a coupled system that has been studied as a possiblenoptical communications source. We find simple expressions for theninstantaneous frequency and intensity in terms of a few parametersncharacterizing the dispersion, allowing for the design of the system tonminimize chirp. From these expressions we also recover Kazarinov andnHenry's adiabatic chirp formula in the limit of slow modulation andnPetermann's dynamical chirp formula in the limit of uniform carrier andnphoton densities. We show that in typical cases, where nonuniformity isnimportant, the instantaneous frequency modulation is quantitatively andnqualitatively different than is predicted by previous models