基于DAST晶体差频的可调谐THz辐射源

Tunable THz Radiation Source Based on DAST Crystal via Difference Frequency Generation

基于自发成核法自行生长的4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲苯酸盐(DAST)晶体,可实现宽带可调谐THz辐射输出。实验探究饱和生长溶液质量浓度对晶体生长形态和光学质量的影响,并结合晶体的拉曼光谱,对其生色团振动和转动特性进行分析。采用波长为1.3~1.5μm的高能量、可调谐双波长的激光为泵浦光,基于0类相位匹配外腔差频和电控振镜快速扫描技术,实现了0.1~20.0THz的宽带THz辐射输出。在18.9THz处,每个脉冲最大输出能量为3.59μJ,转换效率为2.39×10-4。基于宽带THz输出谱可知,DAST晶体对THz波的吸收主要是因为晶格振动引起的。

A 4-dimethylamino-N′-meth-yl-4′-stilbazolium tosylate(DAST)crystal grown by spontaneous nucleation method can realize a tunable broadband THz radiation source.Effects of mass concentration of saturated growth solution on the crystal growth morphology and optical quality are investigated,and the vibration and rotation characteristics of the chromophore are analyzed by the Raman spectrum of the crystal.Using the high-energy and tunable dual-wavelength laser within the wavelength range of 1.3--1.5μm as a pump source,the broadband THz radiation output in the range of 0.1--20.0 THz is achieved by the 0-phase matching external-cavity different frequency and galvano-optical fast scanning technology.The maximum output energy of each pulse is 3.59μJ at 18.9 THz,and the energy conversion efficiency is 2.39×10-4.Based on the broadband THz output spectrum,it is found that the absorption of THz wave by the DAST crystal is mainly caused by lattice vibration.