A novel coherent and tunable THz module for chemical identification

This Small Business Innovation Research (SBIR) Phase I project focuses on the implementation of a Terahertz (THz) module that can emit coherent and tunable Terahertz waves. This project naturally follows the recent result obtained by the Project Investigator. Recently, coherent Terahertz radiation was generated at room temperature, which could be continuously tunable from 56.8 mm to beyond 1618 mm (5.27 to 0.18 THz), in Gallium Selenide, based on difference-frequency generation. The peak Terahertz power can be as high as 69.4 W at 196 mm. The corresponding photon conversion efficiency reaches 3.3%. This value has been greatly improved owing to the combination of extremely low absorption coefficients in the Terahertz domain and a large second-order nonlinear coefficient for Gallium Selenide. On the other hand, it has been demonstrated that optical parametric oscillator in Lithium Niobate can be used to generate a Terahertz wave tunable in the range of 110-460 m (2.7-0.7 THz) with a peak power of 300 W. However, Lithium Niobate suffers from photorefractive damage. One needs a much higher laser intensity to achieve parametric oscillation. The Terahertz source will dramatically impact molecular spectroscopy. Such an instrument can be eventually used to control pollution and to identify toxic chemicals, for remote sensing, bio- medical imaging, and security screening.