基于光电导天线探测的THz-ATR系统设计和性能研究OACSTPCD

In this paper,a terahertz attenuated total reflection(THz-ATR)system based on photoconductive antenna detection was designed and built to prepare for the sensing and detection of trace and low-concentration biochemical macromolecular aqueous solutions.Unlike the THz-TDS test,where the terahertz wave is in direct contact with the sample,the THz-ATR system uses the evanescent wave generated at the interface where total reflection occurs to avoid the strong absorption of terahertz waves by the aqueous solution during the test.The system terahertz light is generated by femtosecond light excited by indium arsenide,which detects a photoconductive antenna using a hemispherical silicon lens to delay echoes in the time-domain spectrum,resulting in high-frequency spectral resolution.The performance of the built THz-ATR system was tested,and its frequency range was 0.2-2 THz,the dynamic range was better than 50 dB,the signal-to-noise ratio was 600:1,and the spectral resolution could reach 3 GHz.Finally,the spectral characteristics of different humidity environments were explored to provide support for subsequent experiments.