Double pulse generation in a highly nonlinear GaAs optical waveguide

Abstract

This paper presents a simulation and investigation about the nonlinear interplay between an optical pulse and GaAs waveguide. The results obtained show that the nonlinear processes including self-phase modulation, 2-photon absorption, and free carrier related effects will have significant influences on the temporal shape and frequency spectrum of a propagating pulse in the GaAs waveguide with the result that 2-photon absorption can extend the pulse duration that can be again compressed by the free carrier absorption. The outcome spectrum is also asymmetrical due to the free carrier related effects, which takes on a complicated oscillation structure resulting from the interference. In addition, an interesting phenomenon is that the input pulse will eventually evolve into a double pulse along the GaAs waveguide by means of judiciously adjusting the intensity, waveform, and time duration of the input pulse, i.e. when the time duration of the input pulse is larger than the carrier lifetime, the input pulse with high enough intensity can develop into a double pulse at the end of the waveguide.