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Proceedings Paper

Enhancement of electro-optic sampling signal in detection of pulsed terahertz waves by polarization filtering (Conference Presentation)
Author(s): Masahiko Tani; Hideaki Kitahara; Hiroyuki Kato; Masaki Shiihara; Akihiro Esaki; Jessica Afalla; Valynn K. Mag-usara; Takashi Furuya; Clare Escano; Kohji Yamamoto; Elmer S. Estacio; Michael I. Bakunov

Paper Abstract

In this paper, we demonstrate significant enhancement of electro-optic (EO) sampling signal in the detection of pulsed terahertz (THz) waves by using a technique we call “polarization filtering”. In the EO sampling of pulsed THz waves, a linearly polarized probe optical pulse is phase-modulated by THz electric field through the linear EO effect and, as the result, it becomes slightly elliptically polarized after passing through the EO crystal. The phase-retardation of the probe optical pulse is then detected as an optical intensity modulation (EO signal), dI/I (the ratio of the intensity change, dI, and the original intensity, I) with an appropriate optical detection system. In “polarization filtering,” the EO sampling signal, dI/I, is enhanced by suppressing the main polarization component of the probe beam, resulting in a reduced probe beam intensity I’ = b^2*I, after the interaction with THz field in the EO crystal. Since the intensity modulation, dI, also reduces to dI’= b*dI, as the result of the polarization filtering, the THz EO sampling signal is enhanced by a factor of 1/b: dI’/I’ =(1/b)*dI/I. This “polarization filtering” is applicable not only to the conventional ellipsometric EO sampling but also to the heterodyne EO sampling. Firstly, we explain the principle of the polarization filtering, and then show the results of the proof-of-principle experiment for the standard and the heterodyne EO sampling, respectively.

Paper Details

Date Published: 14 May 2019
Proc. SPIE 10983, Next-Generation Spectroscopic Technologies XII, 109830Y (14 May 2019); doi: 10.1117/12.2519806
Show Author Affiliations
Masahiko Tani, Univ. of Fukui (Japan)
Hideaki Kitahara, Univ. of Fukui (Japan)
Hiroyuki Kato, Univ. of Fukui (Japan)
Masaki Shiihara, Univ. of Fukui (Japan)
Akihiro Esaki, Univ. of Fukui (Japan)
Jessica Afalla, Univ. of Fukui (Japan)
Valynn K. Mag-usara, Univ. of Fukui (Japan)
Takashi Furuya, Univ. of Fukui (Japan)
Clare Escano, Univ. of Fukui (Japan)
Kohji Yamamoto, Univ. of Fukui (Japan)
Elmer S. Estacio, Univ. of the Philippines Diliman (Philippines)
Michael I. Bakunov, N.I. Lobachevsky State Univ. of Nizhni Novgorod (Russian Federation)

Published in SPIE Proceedings Vol. 10983:
Next-Generation Spectroscopic Technologies XII
Richard A. Crocombe; Luisa T.M. Profeta; Abul K. Azad, Editor(s)

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