A new THz-to-millimeter-wave source

"This SBIR Phase I project focuses on the implementation of a new THz module that can emit coherent and tunable THz waves. Recently, coherent THz radiation was generated at room temperature by PI, with a tuning range of 56.8-1618 ¿m (5.27 - 0.18 THz), inGaSe based on difference-frequency generation. The peak THz power can be as high as 69.4 W at 196 ¿m. The corresponding photon conversion efficiency reaches 3.3%. The objectives for Phase I include optimized design and detailed testing of the THz module.This module consists of all the optics, opto-mechanical components with knobs for adjustments, a mounted GaSe crystal, and a GaAs etalon for THz wavelength measurements. This module can be initially pumped by two laser beams, e.g., Nd:YAG laser and MOPOsystem.Presently, electro-optic sampling becomes a widely-accepted technique in the THz domain. However, for some applications such as the identifications of substances by the absorption of THz waves, there is a critical need for the development of a coherentquasi-CW THz source. To be usable for this application, the THz radiation should have high coherence, a narrow linewidth, a high power, and a low divergence angle. Such a type of the instrument can be eventually used for target acquisition as well astracking and pointing. It also has applications in pollution monitoring, identifying toxic chemicals, remote sensing, molecular spectroscopy, bio-medical imaging, and security screening. I