Non-Uniform Grating Effects on Time-Dependent Bistable Characteristics of QWS-DFB Semiconductor Laser Amplifiers

In this paper, using a proposed procedure we analyze temporal behavior of bistable quarter wavelength shifted distributed feedback (QWS-DFB) semiconductor laser amplifiers based on a time-dependent model. In a QWS-DFB laser amplifier, we find that this model yields the shapes of the hysteresis curves which qualitatively agree with those based on the steady-state model for long signal-modulation periods. The results show that for modulation periods approaching the carrier life time, the hysteresis curve will close down, but the distortion of the bistable characteristics due to short modulation periods is reduced for non-uniform grating QWS-DFB laser amplifiers. The transfer matrix method (TMM) is utilized for simulating all results.