高功率太赫兹脉冲半导体探测器的分析与设计

Analysis and design of semiconductor detector for high-power terahertz pulse

设计了一种基于半导体热电子效应的0.14THz高功率脉冲探测器.首先根据探测器的结构特点,分析了探测器的工作原理,并推导了探测器的相对灵敏度表达式.接着采用三维电磁场时域有限差分法,模拟计算了探测器的电压驻波比和线性区的相对灵敏度.在优化的结构参数下,探测器在0.14THz波段的电压驻波比不大于1.3,相对灵敏度约为0.6kW-1,且在0.13—0.16THz频带内波动不超过10%.然后讨论了焦耳热效应对探测器的影响,考察了太赫兹脉冲宽度与输出电压变化率的关系.最后对探测器的检波模拟和分析结果表明,探测器最大承受功率约为2.2kW,线性工作区最大功率达数十瓦,响应时间为皮秒量级,可完成0.14THz纳秒级高功率太赫兹脉冲的直接测量,提高其功率测量的精度.

A 0. 14 THz high-power terahertz pulse detector based on hot electron effect in semiconductors is designed in this paper. First,the working principle of the detector is analyzed and its relative sensitivity is derived according to the structural characteristics of the detector. Then a three-dimensional finite-difference time-domain method is used to simulate the voltage standing wave ratio （VSWR） and relative sensitivity in a linear region. With optimized structural parameters, the VSWR of the designed detector is less than 1. 3 while the relative sensitivity is about 0. 6 kW^-1,fluctuating no more than 10% in a frequency range of 0. 13—0. 16 THz. Subsequently discussed are the effect of Joule heat on the detector, and the relation between variation ratio of the output voltage and terahertz pulse duration. Finally the detecting simulations of the detector and its analysis results show that the detector with response time of picosecond-leval can handle a maximum power of about 2. 2 kW,while the maximum power of its linear working region reaches tens of watts,so it can accomplish the direct measuring of 0. 14 THz high-power terahertz pulses with nanosecond-level durations,increasing the accuracy of power measurement.