Non-trivial scaling of self-phase modulation and three-photon absorption in III-V photonic crystal waveguides

Abstract

We investigate the nonlinear response of photonic crystal waveguides with suppressed two-photon absorption. A moderate decrease of the group velocity (approximately c/6 to c/15, a factor of 2.5) results in a dramatic (x 30) enhancement of three-photon absorption well beyond the expected scaling, proportional, variant 1/v3g. This non-trivial scaling of the effective nonlinear coefficients results from pulse compression, which further enhances the optical field beyond that of purely slow-group velocity interactions. These observations are enabled in mm-long slow-light photonic crystal waveguides owing to the strong anomalous group-velocity dispersion and positive chirp. Our numerical physical model matches measurements remarkably.

Soliton Pulse Propagation in the Presence of Disorder-Induced Multiple Scattering in Photonic Crystal Waveguides

“…As we the increase the group index to β 1 = 13.782, the effect of multiple scattering begins to manifest in the spectral domain via the generation of a fine peak structure that slightly distorts the transmission spectrum whilst giving rise to a non-negligible reflection. This is in very good agreement with related experimental spectra obtained for similar group indices [2,3]. For β 1 = 24.69, which lies in the slow light regime, the transmission is greatly reduced and reflection enhanced as disorderinduced scattering now dominates over the Kerr nonlinearity as one sees large pulse distortion in the spectral domain.…”

“…When nonlinearities dominate over multiple scattering, the soliton's spectra shows a random fine peak structure, whereas when multiple scat- tering dominates, the soliton's spectra exhibits narrow spectral peaks indicative of disorder-induced photon localization. Our numerical results are able to capture unexplained experimental features related to multiple scattering [2,3,19] and our formalism can be generalized to assess the impact of multiple scattering on other nonlinearities such as 2PA, 3PA, self-steepening, four-wave mixing, etc.…”

Nonlinear properties of dispersion engineered InGaP photonic wire waveguides in the telecommunication wavelength range

“…Heterogeneously integrated III-V materials on a silicon substrate have already been extensively studied for on-chip light generation [11][12][23][24]. Previous studies have explored the nonlinear properties of photonic wire waveguides and photonic crystal waveguides realized on their III-V growth substrate based on different III-V materials, including InGaP, for a range of nonlinear optics applications [14][15][16][17][18][19]22].…”

Giant anomalous self-steepening in photonic crystal waveguides

“…For a typical wavelength of 1550 nm (photon energy of 0.8 eV), silicon (E g = 1.1 eV) is restricted by two-photon absorption (TPA), and the wide-gap material GaInP (E g = 1.9 eV) is limited by three-photon absorption (3PA). While the optical properties of silicon have been widely studied, only over the past few years have we investigated the χ (3) properties of GaInP and established this material as a viable platform for nonlinear optics at 1.5 μm [12,22,32,36]. In simplest terms, nonlinear absorption damps the dynamics similar to linear absorption.…”

“…For the modeling below, we take the slow-light-scaled values of the bulk parameters as described in prior literature [36,40]. The parameters are α 3eff = α 3…”