全光纤耦合异步光学采样THz-TDS系统  

Fiber-Coupled Asynchronous Optical Sampling THz-TDS System

作　　者：段国腾 李林[1] 崔海林[2] 张存林[2] 

机构地区：[1]北京理工大学光电学院,北京100081 [2]首都师范大学物理系,北京100048

出　　处：《北京理工大学学报》2016年第2期170-174,共5页Transactions of Beijing Institute of Technology

摘　　要：针对传统THz-TDS系统利用机械步进延迟线进行采样扫描的方式获取太赫兹时域谱使得检测信号速度慢等缺点,设计了全光纤耦合快速异步光学扫描THz-TDS系统,该系统利用以锁相环(PLL)和直接频率合成器(DDS)为核心的电子系统精确控制两台飞秒激光器重复频率,使之有较小的固定频差,使两台飞秒激光器的脉冲之间产生周期性呈线性增长的相位延迟,实现了一个脉冲对另一个脉冲的毫秒级快速扫描.结果表明,该系统对太赫兹脉冲的扫描时间缩短为2ms,实际采样频率可达到1GHz.有效解决了以往太赫兹光谱检测速度慢、便携性差等问题,从而进一步拓展了太赫兹光谱测量的应用范围.Conventional THz-TDS systems employ a stepped delay line for their optical delay line scan and utilize lock-in amplifier for acquisition of THz signal.In this approach,the speed of THz signal sampling is too slow to be introduced into some applications which require a highspeed performance.A terahertz time-domain spectroscopy（THz-TDS）based on fiber-coupled high-speed asynchronous optical sampling was proposed.An electronic system was used which included phase-locked loop（PLL）and the direct frequency synthesizer（DDS）to fix the frequency difference between the two femtosecond laser repetitions to achieve periodic liner increasing of phase delay and millisecond fast scan of the terahertz pulse.The results show that the system can shorten the scanning time of terahertz pulse to 2ms,and the actual sampling frequency can reach1 GHz.It effectively solves the problems of slow detection speed and poor portability in the past,and further expands the application range of terahertz spectrum measurement.

关 键 词：异步光学采样 太赫兹时域光谱 光纤 

分 类 号：O433.1[机械工程—光学工程]