Observation of Nondegenerate Two-Photon Gain in GaAs

TL;DR

This paper reports the experimental observation of nondegenerate two-photon gain in GaAs, showing a significant enhancement that could enable the development of two-photon semiconductor lasers.

Contribution

First demonstration of nondegenerate two-photon gain in GaAs using femtosecond pump-probe measurements, with nearly two orders-of-magnitude enhancement.

Findings

Nearly two orders-of-magnitude increase in 2PG coefficient

Isolation of 2PG from other effects using polarization techniques

Potential pathway for two-photon semiconductor laser development

Abstract

Two-photon lasers require materials with large two-photon gain (2PG) coefficients and low linear and nonlinear losses. Our previous demonstration of large enhancement of two-photon absorption in semiconductors for very different photon energies translates directly into enhancement of 2PG. We experimentally demonstrate nondegenerate 2PG in optically excited bulk GaAs via femtosecond pump-probe measurements. 2PG is isolated from other pump induced effects through the difference between measurements performed with parallel and perpendicular polarizations of pump and probe. An enhancement in the 2PG coefficient of nearly two orders-of-magnitude is reported. The results point a possible way toward two-photon semiconductor lasers.