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

TL;DR

This paper explores the nonlinear optical response in photonic crystal waveguides, revealing a surprising 30-fold increase in three-photon absorption due to pulse compression and slow-light effects, with implications for nonlinear photonics.

Contribution

It demonstrates a non-trivial scaling of three-photon absorption in slow-light photonic crystal waveguides, highlighting the role of pulse compression and dispersion in enhancing nonlinear interactions.

Findings

30x enhancement of three-photon absorption beyond expected scaling

Pulse compression significantly boosts optical field in slow-light regimes

Numerical model accurately matches experimental measurements

Abstract

We investigate the nonlinear response of photonic crystal waveguides with suppressed two-photon absorption. A moderate decrease of the group velocity (~ c/6 to c/15, a factor of 2.5) results in a dramatic (30x) enhancement of three-photon absorption well beyond the expected scaling, proportional to 1/(vg)^3. 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.