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

Abstract

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.

High-power terahertz pulse sensor with overmoded structure

“…To effectively measure the power of the high power terahertz wave, a novel fundamental-mode resistive sensor (RS), based on the hot electron effect in semiconductor in high electric field, [12][13][14][15] was developed and used to detect the power generated by a high power surface wave oscillator working at 0.14 THz. [8,9,12] We are currently developing a new high power terahertz wave source working at 0.34 THz, [11] and we have designed a similar sensor by placing a silicon bar in the WR 2.8 waveguide working at the fundamental mode. [16,17] However, there are two difficulties.…”

High-power TM 01 millimeter wave pulse sensor in circular waveguide

“…Referring to our previous work on the resistive sensors (RS) used in a rectangular waveguide, [14][15][16] the sensing structure for the millimeter wave of the TM 01 mode in a circular waveguide is proposed and shown in Fig. 1.…”

“…Let us consider the sensitivity of the proposed sensing structure for TM 01 mode millimeter wave with power P in in the circular waveguide. According to the scattering theory of electrons in a semiconductor, the resistance change ∆R/R 0 of the SE under a high electric field satisfies the equation [14] ∆R R 0 4…”

“…Second, the initial resistance of the SE should be in the vicinity of 50 Ω to match the external circuits and have a response time in the picosecond level. [14] Finally, a flat frequency response of relative sensitivity in the 300-400 GHz range is preferable. Besides, it is worth mentioning that the ranges and precisions of parameters that can reach for practical n-Si materials used for the SE should be considered before proceeding with finetuning of the parameters to optimize the sensing structure.…”