The role of nonlinear optical absorption in narrow-band difference frequency terahertz-wave generation

TL;DR

This paper analyzes how nonlinear optical absorption affects the efficiency of narrow-band difference frequency terahertz-wave generation, providing universal charts and insights into maximum conversion efficiency considering multiphoton absorption effects.

Contribution

It introduces a normalized analytical framework including multiphoton absorption, enabling universal phase-matched conversion charts and predicting efficiency limits for terahertz generation.

Findings

Universal charts for phase-matched conversion considering nonlinear absorption

Assessment of multiphoton absorption impact on terahertz generation

Predictions of maximum achievable conversion efficiency at high pump intensities

Abstract

We present a general analysis of the influence of nonlinear optical absorption on terahertz generation via optical difference frequency generation, when reaching for the quantum conversion efficiency limit. By casting the equations governing the process in a suitably normalized form, including either two-photon- or three-photon-absorption terms, we have been able to plot universal charts for phase matched optical-to-terahertz conversion for different values of the nonlinear absorption coefficients. We apply our analysis to some experiments reported to date, in order to understand to what extent multiphoton absorption could have played a role and also to predict the maximum achievable conversion efficiency at higher peak pump intensities.