Light localization induced enhancement of third order nonlinearities in a GaAs photonic crystal waveguide

Abstract

Nonlinear propagation experiments in GaAs photonic crystal waveguides (PCW) were performed, which exhibit a large enhancement of third order nonlinearities, due to light propagation in a slow mode regime, such as two-photon absorption (TPA), optical Kerr effect and refractive index changes due to free-carriers generated by TPA. A theoretical model has been established that shows a very good quantitative agreement with experimental data and demonstrates the important role that the group velocity plays. These observations give a strong insight into the use of PCWs for optical switching devices.

Double pulse generation in a highly nonlinear GaAs optical waveguide

“…The intensity change will also influence the spectral property of the output pulse illustrated in Figure 2b, where the spectrum bandwidth is significantly broadened, and a majority of pulse energy is blue-shifted as a result of enhanced free carrier related effects under the condition of high input peak level. The spectrum property shown is similar to the reported experiment result as the initial intensity is gradually enhanced [12,24]. Now, let us focus on the influence of changed time duration on the output pulse at the end of a 1-mm long waveguide, where the output pulse shapes and frequency spectra are, respectively, depicted for 3 cases of t 0 = 10 ps, 30 ps, and 50 ps in Figures 3a and 3b.…”

Slow light enhancement of nonlinear effects in silicon engineered photonic crystal waveguides

“…It has long been predicted that the slow light enhancement of light-matter interaction should induce a reduction of either the physical length of waveguide or input power needed to observe nonlinear phenomena such as stimulated Raman scattering or harmonic generation [3,4]. However, demonstrations of such enhancement process are still rare [5] and preliminary, partly due to the challenging increase of coupling loss, linear [6] and nonlinear losses as well as the large high order dispersion that typically cause pulse distortion in the slow light regime [7].…”

Saturation of the Raman amplification by self-phase modulation in silicon nanowaveguides

“…Beyond the measurement method proposed, this work provides insight in the study of slow-mode Raman devices. Indeed, increasing the group index of both pump and signal beams, for the purpose of compactness and low-command power, will be detrimental to SRS because of the simultaneous enhancement of the spectral broadening of the pulses, in particular through the phase modulation effects 15 . Accurate understanding of the interaction between SRS and phase modulation is crucial in the study of Raman functionality.…”