Analysis of mode behavior in a waveguide with graded index and gain

Abstract

Abstract-Numerical analysis has been carried out for a waveguide with graded index and gain. I t is shown that the radiation peak of the fundamental mode is deflected as the gradient of either the index or gain increases. The high-order modes also change their peak intensity ratio as the gradient of index or gain increases. The behavior of the fundamental mode is suitable for use in a beam scanner while that of higher-order modes is suitable for use in a deflection switching of laser beams. The analysis also shows that the modal gain of higher-order modes becomes larger than that of the fundamental mode as the gradient of the index and gain increases, which provides some explanation for the wide laser beam scanning observed by Scifres et al.

Gain Switching of Monolithic 1.3 μm InAs/GaAs Quantum Dot Lasers on Silicon

“…To simulate the measured gain-switched pulses, a modal gain on the order of 20 cm -1 is, therefore, needed to reproduce the experimental pulse rise times. Yet after all it is important to bear in mind that the transverse variations occurring over the width of the 50 μm waveguides in the local gain, the carrier density, and the photon density, allow for substantial variations in the observed device performance, and thus in the associated simulation parameters [45], [46]. It is, therefore, expected that greater confidence about laser parameters likely to be obtained in Si-based 1.3 m QD lasers can be achieved through further experiments with narrow ridge-waveguide lasers.…”