Iris-assisted Terahertz Field-Induced Second Harmonic Generation in Air

TL;DR

This paper demonstrates that inserting an iris into the interaction region significantly amplifies terahertz-induced second harmonic signals in air, enabling enhanced detection and study of nonlinear phase-matching in gases.

Contribution

The study introduces an iris-assisted method to greatly enhance TFISH signals in air, providing a new platform for nonlinear phase-matching research in the gas phase.

Findings

TFISH signal increases by tens of times with an iris in air.

Amplification varies with air pressure and probe intensity.

Platform enables detailed study of nonlinear phase-matching in gases.

Abstract

Terahertz field-induced second harmonic generation (TFISH) is a technique for optical detection of broad-band THz fields. We show that by placing an iris at the interaction volume of the THz and optical fields, the TFISH signal increases by few ten-fold in atmospheric air. The iris-assisted TFISH amplification is characterized at varying air pressures and probe intensities and provides an elegant platform for studying nonlinear phase-matching in the gas phase.