Numerical simulation of the generation of picosecond pulses with gain-switched DFB lasers

Abstract

We discuss the numerical generation of picosecond pulses in gain-switched distributed feedback (DFB) lasers using the traveling-wave equation model. The principle of pulse generation is discussed, which consists of injection of trapezoidal - shaped injected current, which leads to an fast increase in carrier density, followed by an abrupt decrease that result in a pulse shape of the output power. We report improvements in the shape and peak of the pulses, as well as a reduction of pulse width. Our findings suggest that these lasers can produce pulses with a peak power exceeding 1.0 W and a pulse width of less than 10 ps. We investigated the effect of various parameters, such as injected currents, the width of the active region, the pulse length of the trapezoid of injected current, and both the rise and fall times of the injected current affect the primary pulse characteristics, including peak power, energy, and full width of half maximum (FWHM). We present a set of geometrical and material parameters for a system, that could provide an experimental demonstration of the theoretical results obtained. Finally, we identified the optimal parameters for applications requiring short pulses.