Abstract-Terahertz Detection With a Low-Cost Packaged GaAs High-Electron-Mobility Transistor

Elham Javadi,  Alvydas Lisauskas,  Mahmoud Shahabadi,  Nasser Masoumi , Jingshui Zhang, 
Johann Wolfgang Goethe

https://ieeexplore.ieee.org/document/8506393

We present experimental results of an investigation into the performance of a commercial, packaged GaAs high-electron-mobility transistor (HEMT) as a detector of terahertz (THz) radiation in the frequency ranges 0.22–0.32 and 0.520–0.650 THz. Enclosed in a standard ceramic housing and without a dedicated antenna for radiation coupling, the transistor is capable of sensitive direct detection (power detection) of THz radiation at room temperature. The device responsivity shows a strong variation with wavelength, indicating that various device features (transistor metallization, contact pads, wires) act as an effective THz antenna. With the THz radiation focused with a parabolic mirror (and without a substrate lens), the maximum responsivity reaches 2.5 and 0.72 V/W with values of the minimum optical noise-equivalent power (NEP) of 1.4 and 2.5 nW/ Hz−−−√ at the sensitivity peaks at 0.271 and 0.632 THz, respectively. The performance of the HEMT, in comparison with antenna-coupled FET detectors optimized for THz detection (TeraFETs), can be assessed better if the responsivity and the NEP are referred to the effective antenna cross-section determined experimentally for the device. We arrive at a cross-sectional responsivity of 42 V/W (1.6 V/W) and a cross-sectional NEP of 135 pW/ Hz−−−√ (1250  pW/ Hz−−−√ ) at 0.271 THz (0.632 THz), for measurements through the ceramic cap. The cross-sectional NEP values are about one order of magnitude at 0.271 THz and two orders of magnitude at 0.632 THz higher than those achieved with the best TeraFETs, yet in a range where they enable many practical applications at low cost for the detector.

Abstract-Terahertz wave polyethylene lens based on wave front phase modulation

Tielin Lu; Xiaohu Guo; Lingqin Kong; Yuejin Zhao; Jingshui Zhang; Shijing Zhang

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10383/103830M/Terahertz-wave-polyethylene-lens-based-on-wave-front-phase-modulation/10.1117/12.2273282.short


Terahertz(THz) wave modulator technology, due to its important value of imaging and detecting research. In the paper, we discuss the Polyethylene lens based the terahertz wave front modulation, which is benefit the terahertz wave image technology. Simulation results show that the optical system can extent the depth of imaging field of test objects based on continuous terahertz source. The way to get the image has significant meaning for detection and large image quality.

© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Coherent detection for continuous terahertz wave

Hui Yuan, Tielin Lu, Jingshui Zhang, Yuejin Zhao

Beijing Institute of Technology (China)

Liangliang Zhang, Ji Zhao

Capital Normal Univ. (China)

Proc. SPIE 9585, Terahertz Emitters, Receivers, and Applications VI, 95850O (August 31, 2015); doi:10.1117/12.2187465

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2434792

In this paper we demonstrated a coherent raster-scan imaging system that can acquire phase information based on continuous terahertz imaging. It mixes the terahertz with a Fs-laser by a electro-optic crystal of ZnTe to make a hybrid modulation on the crystal to achieve continuous terahertz detection. In this way, it can not only propagate for a long distance but also achieve phase detection for continuous terahertz imaging. The surface images of objects that are under test can be obtained by the Backward-Wave Oscillator, which the output power is 10mW at 205.994GHz. With the repetition frequency of 80MHz, the output power of the MaiTai is 1.65W and 100fs pulse light at 800nm. The images can achieve diffraction-limited resolution approximately. And the simulated results show that the system can obtain phase imaging of test objects based on continuous terahertz source. The way to get the phase of the signal has significant meaning for coherent detection of continuous terahertz source.
 © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.