基于频率梳的太赫兹辐射功率密度测量

Terahertz spatial radiant power density measurements based on terahertz frequency comb

为实现太赫兹辐射特性精准认知,开展太赫兹辐射功率密度测量研究.通过光学频率梳产生太赫兹频率梳,利用太赫兹频率梳实现太赫兹辐射源空间辐射功率密度测量.本文利用电光采样和光电导探测两种方式,实现了100 GHz辐射源空间辐射功率密度测量;将100 GHz辐射总功率溯源到标准太赫兹功率计,实现太赫兹辐射功率密度绝对测量.分析比较了利用800 nm空间光进行电光采样和利用1 550 nm光纤激光进行光电导探测的测量结果.在不同距离下,对太赫兹辐射源的空间辐射功率密度进行了测量和量值溯源,实验揭示了太赫兹辐射传输的空间演化特性.

Terahertz frequency comb,which is generated from femtosecond frequency comb,is applied to measure the spatial radiant power density of terahertz source.Two technologies,electro-optic sampling and photoconductive detection,are applied to generate terahertz frequency comb,and the spatial power density of a 100 GHz source is measured with both of these two techniques.The total radiant power is traceable to a standard terahertz radiometer,and the absolute power density of the terahertz source is obtained.The measurement results with both of the two techniques,electro-optic sampling with 800 nm femtosecond optical pulse in free space and photoconductive antenna detection with 1 550 nm femtosecond optical pulse in fiber,are analyzed and compared.Moreover,the spatial power density of the terahertz radiation at different distance away from the terahertz source are measured,and the involvement of the terahertz radiation in free space is experimentally studied.