SBIR Phase I: A Novel Coherent and Tunable Terahertz (THz) Module for Chemical Identification

这个小企业创新研究（SBIR）第一阶段项目的重点是实现一个太赫兹（THz）模块，该模块可以发射相干和可调谐的太赫兹波。这个项目自然遵循了项目调查员最近获得的结果。最近，在硒化镓中，基于差频产生，在室温下产生了相干太赫兹辐射，该辐射可以在56.8 mm到1618 mm（5.27到0.18太赫兹）之间连续可调。在196毫米处，峰值太赫兹功率可高达69.4瓦。相应的光子转换效率达到3.3%。由于硒化镓在太赫兹域中极低的吸收系数和较大的二阶非线性系数的结合，该值得到了极大的提高。另一方面，研究表明，铌酸锂中的光学参量振荡器可以产生110-460 m （2.7-0.7 THz）范围内的太赫兹波，峰值功率为300 W。然而，铌酸锂存在光折变损伤。人们需要更高的激光强度来实现参量振荡。太赫兹源将极大地影响分子光谱学。这种仪器最终可用于控制污染和识别有毒化学品，用于遥感、生物医学成像和安全检查。

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.