Abstract-Polarization-variable emitter for terahertz time-domain spectroscopy

Dmitry S. Bulgarevich, Makoto Watanabe, Mitsuharu Shiwa, Gudrun Niehues, Hideaki Kitahara, and Masahiko Tani
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-24-27160

We report on the progress in the development of linear polarization-variable multi-electrode emitters for terahertz time-domain spectroscopy. The results on its microfabrication, the finite element method modeling of appropriate bias distribution between electrodes, the finite-difference time-domain simulated spectral output, and actual experimental testing are presented. The rotation of the emitted terahertz field with linear polarization on an angle multiple of 45° can be achieved by synchronized bias and single polarizer rotations.

© 2016 Optical Society of America

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Abstract-Low temperature-grown GaAs carrier lifetime evaluation by double optical pump terahertz time-domain emission spectroscopy

Valynn Katrine Mag-usara, Stefan Funkner, Gudrun Niehues, Elizabeth Ann Prieto, Maria Herminia Balgos, Armando Somintac, Elmer Estacio, Arnel Salvador, Kohji Yamamoto, Muneaki Hase, and Masahiko Tani

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-23-26175

We present the use of a “double optical pump” technique in terahertz time-domain emission spectroscopy as an alternative method to investigate the lifetime of photo-excited carriers in semiconductors. Compared to the commonly employed optical pump-probe transient photo-reflectance, this non-contact and room temperature characterization technique allows relative ease in achieving optical alignment. The technique was implemented to evaluate the carrier lifetime in low temperature-grown gallium arsenide (LT-GaAs). The carrier lifetime values deduced from “double optical pump” THz emission decay curves show good agreement with data obtained from standard transient photo-reflectance measurements on the same LT-GaAs samples grown at 250 °C and 310 °C.

© 2016 Optical Society of America

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Abstract-A matter of symmetry: terahertz polarization detection properties of a multi-contact photoconductive antenna evaluated by a response matrix analysis

Gudrun Niehues, Stefan Funkner, Dmitry S. Bulgarevich, Satoshi Tsuzuki, Takashi Furuya, Koji Yamamoto, Mitsuharu Shiwa, and Masahiko Tani
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-12-16184

While terahertz time domain spectroscopy (THz-TDS) is a well-established technique, polarization sensitive measurements are challenging due to the need of broadband polarization devices. Here, we characterize our recently introduced multi-contact photoconductive detector antenna with a response matrix analysis. We show that the lead lines attached to electrodes reduce the antenna symmetry and thereby influence the properties of the response matrices. With a wire grid polarizer, we simulate a sample influencing the polarization angle and the intensity of the incident THz pulse. Evaluating the measurements with the response matrix analysis, our results show a well agreement of the adjusted and measured polarization angles and intensities over a frequency range from 0.25 to 0.8 THz.

© 2015 Optical Society of America

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Abstract-A polarization-sensitive 4-contact detector for terahertz time-domain spectroscopy

Dmitry S. Bulgarevich, Makoto Watanabe, Mitsuharu Shiwa, Gudrun Niehues, Seizi Nishizawa, and Masahiko Tani  »View Author Affiliations

Optics Express, Vol. 22, Issue 9, pp. 10332-10340 (2014)
http://dx.doi.org/10.1364/OE.22.010332

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-9-10332

A light polarization angle-sensitive photoconductive detector for terahertz time-domain spectroscopy is computer-modeled, microfabricated, and tested. The experimental results show good agreement with the linear angular response for an ideal detector. The detector’s frequency, angular, and crosstalk responses are discussed in the context of theoretical and experimental considerations.

© 2014 Optical Society of America