探测光波长对太赫兹波电光取样探测技术的影响

摘要

由于太赫兹波电光取样探测技术中电光晶体存在的色散关系,探测光的波长会直接影响到电光取样的探测带宽和效率.由于该色散关系的存在,不同的电光晶体在电光取样中响应函数不同.本文研究了两种典型的电光晶体-碲化锌和磷化镓晶体的响应函数,发现在选取的四种探测激光波长内(600 nm、800 nm、1200 nm、1600 nm),800 nm的探测激光更合适碲化锌晶体,1200 nm的激光更合适磷化镓晶体.对于不同厚度的晶体,存在一个最优化的探测激光波长,使得该晶体的电光响应函数有最宽的带宽.%The wavelength of the probe laser can affect the bandwidth and the efficiency of terahertz electro-optic sampling (EOS) detection method because of the relationship of velocity match between the terahertz phase velocity and the laser group velocity.An electro-optic (EO) crystal has different dispersion with different lasers,thus the wavelength of the probe laser for a given EO crystals have different influence on the EOS detection.The response functions of EOS systems based on two typical EO crystals,ZnTe and GaP,have been studied.The results show that the probe laser with wavelengths of 800 nm and 1200 nm are more suitable for the ZnTe-and GaP-based EOS system,respectively,than other selected wavelengths (600 nm,800 nm,1200 nm and 1600 nm).We also found that for a given thickness of an EO crystal,there exists an optimal wavelength for the probe laser pulse to obtain the broadest response function with high value.