用于自由电子激光THz源的频谱测量方法

Spectrum measurement method for free electron laser terahertz source

为解决自由电子激光THz(FEL-THz)源在调试初期输出功率低,且实验大厅存在射线对电子测量设备的辐射干扰条件下THz信号频谱测量问题,利用步进模式的傅里叶变换红外光谱仪获取探测器信号,采用高速数据采集卡对信号进行采集,并编写程序对数据进行处理.搭建了面向自由电子激光THz源调试初期的频谱测量系统,并利用商业量子级联激光器在不同重复频率和输出功率下对系统进行了可靠性验证.结果表明该方法适用于重复频率1 Hz以上、平均功率mW量级的脉冲THz信号的频谱测量.

To solve the problem of spectrum measurement under conditions that the power generated by the free electron laser terahertz(FEL-THz) source is low during the debugging process,and there is also strong radiation interference on the electronic measurement equipment,the stepper-mode of Fourier transform infrared spectrometer was used to obtain the detector signal,the high-speed data acquisition card was utilized to collect discrete signal points,and a homemade program was written to process the signal.The spectrum measurement system was successfully realized for the initial commissioning of the FEL-THz source,and a commercial quantum cascade laser was used to verify the reliability of the system at different levels of repetition rate and output power.Results show that this method is well suitable for the spectrum measurement of THz pulse with repetition rate higher than 1 Hz and average power in the level of μW.