Optics letters | 2019
Iris-assisted terahertz field-induced second-harmonic generation in air.
Abstract
Terahertz field-induced second-harmonic generation (TFISH) is a technique for optical detection of broadband THz fields. We show that by placing an iris at the interaction volume of the THz and optical fields, the TFISH signal increases by several tenfold 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.