Highly efficient narrowband terahertz generation driven by a two-spectral-line laser in PPLN

TL;DR

This paper reports highly efficient narrowband terahertz generation using a novel two-spectral-line laser and cascaded difference frequency generation in PPLN, achieving record conversion efficiencies of up to 0.9%.

Contribution

Introduction of a customized two-line laser source and optimized PPLN crystals for enhanced narrowband THz generation efficiency.

Findings

Achieved up to 0.9% conversion efficiency.

Demonstrated effectiveness at cryogenic and room temperatures.

Optimized crystal length and poling period for maximum efficiency.

Abstract

We demonstrate record conversion efficiencies of up to 0.9 percent for narrowband (1 percent relative bandwidth) THz generation by strongly-cascaded difference frequency generation. These results are achieved using a novel laser source, customized for high efficiencies, with two narrow spectral lines of variable separation and pulse duration (250 ps). THz generation in 5 percent MgO doped PPLN crystals of varying poling period was explored at cryogenic and room temperature operation as well as different crystal lengths. This work addresses an increasing demand for high-field THz pulses which has, up to now, been largely limited by low optical-to-THz conversion efficiencies.