Exploiting the optical quadratic nonlinearity of zincblende semiconductors for guided-wave terahertz generation: a material comparison

TL;DR

This paper compares various zincblende semiconductor waveguides for efficient terahertz generation via optical difference frequency generation, introducing a figure of merit to evaluate their performance considering dispersion, absorption, and mode properties.

Contribution

It introduces a general figure of merit for comparing dielectric waveguides for terahertz DFG, enabling optimized material and configuration selection.

Findings

GaP and GaAs waveguides show highest efficiency predictions.

Waveguides can approach quantum efficiency limits with kW optical powers.

The analysis accounts for dispersion, absorption, and mode properties.

Abstract

We present a detailed analysis and comparison of dielectric waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.