Narrow linewidth and wideband tunable continuous-wave terahertz generator based on difference frequency generation with DAST crystal

Abstract

A narrow linewidth and wideband tunable continuous-wave terahertz generator with DAST crystal has been demonstrated in this paper. Two narrow-linewidth CW fiber lasers were used as the pump sources for difference frequency generation. The terahertz wave can be continuously tunable in the range of 1.1-3 THz. The maximum output power of 2.79nW was obtained at 2.568 THz. The linewidth of the output THz wave was estimated to be 56.5 MHz by fitting transmission spectrum of CO gas at 450 Pa pressure around 80.52 cm-1 with the Vogit gas model. Furthermore, the output spectra at room temperature and pressure was in good agreement with the air absorption lines in Hitran database. Moreover, the narrower absorption characteristic spectrum of 2-Deoxy-D-Glucose sample has been obtained through the spectrum measurements. Therefore, it could promote the practical prospect of tunable CW-THz source, which will have good potential in THz high-precision spectroscopic detection and multispectral imaging.

Fabrication and Characterization of 2D Nonlinear Structures Based on DAST Nanocrystals and SU-8 Photoresist for Terahertz Application

“…Several groups in the world have examined different nonlinear materials for THz emission by optical rectification. These materials include organic salts such as dimethyl amino 4-N-methylstilbazolium tosylate (DAST) [14][15][16][17][18], dielectric inorganic electro-optical materials like LiTaO 3 , and semiconductors such as GaAs and GaP [19]. Among them, DAST is the most efficient THz rectification material [20,21], due to its large electro-optics coefficient and its low dielectric constant (ϵ = 5.2), giving rise to a high modulator figure of merit [21].…”