International Journal of Terahertz Science and Technology
  TST >> Vol.4, No.3, September 2011: PP. 137-148
 

Cross-polarization Response of a Two-contact Photoconductive Terahertz Detector

Yandong Gong *, Hui Dong and Zhining Chen
Institute for Infocomm Research, 1 Fusionopolis Way, # 21-01 Connexis South, Singapore 138632
* Email: gongyd@i2r.a-star.edu.sg

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Abstract: The cross-polarization response of a two-contact photoconductive terahertz (THz) detector, is experimentally found in the polarization state measurement of THz radiation in THz time-domain spectroscopy (THz-TDS). It means that this detector responded to a mixture of the two polarization components of THz radiation and such a response is frequency dependent. To evaluate this response quantitatively, three parameters are presented and measured. In the measurement of THz-TDS, such a detector response will result in the distortion of the measured THz spectrum. As a consequence, it will reduce the dynamic range of the system in some frequency bands. In some special cases, it may even lead to a fake "absorption peak" in the THz spectrum. Furthermore, when such a detector is used to measure the polarization state of THz radiation with the assistance of THz polarizers, it will be impossible to decide the optimum orientations of the polarizers as its cross-polarized response is frequency dependent. Finally, we experimentally demonstrated that this effect could be partially eliminated by adjusting the focusing condition of the probe laser beam on the antenna.

Keywords:Terahertz time-domain spectroscopy, Photoconductivity, Polarization.

Published: 2011-9-30

Acknowledgments: This work is supported by the international joint project between A-STAR of Singapore and JST of Japan with A-STAR/SERC/SICP grant No. 1021630069.

Cite this article:
Yandong Gong, Hui Dong and Zhining Chen. Cross-polarization Response of a Two-contact Photoconductive Terahertz Detector[J]. International Journal of Terahertz Science and Technology, 2011, Vol.4, No.3: 137-148.  DOI:10.11906/TST.137-148.2011.09.21

URL: http://www.tstnetwork.org/10.11906/TST.137-148.2011.09.21

 

 
 

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