Abstract-Polarization-sensitive electro-optic detection of terahertz wave using three different types of crystal symmetry: Toward broadband polarization spectroscopy

Kenichi Oguchi¹, Hotsumi Iwasaki¹, Makoto Okano¹ and Shinichi Watanabe^1,a)
http://scitation.aip.org/content/aip/journal/apl/108/1/10.1063/1.4939510
1 Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
a) Author to whom correspondence should be addressed. Electronic mail:watanabe@phys.keio.ac.jp
Appl. Phys. Lett. 108, 011105 (2016); http://dx.doi.org/10.1063/1.4939510

We investigated polarization-sensitive electro-optic (EO) detection of terahertz (THz) waves by using two uniaxial crystals: a c-cut gallium selenide and a c-cut lithium niobate crystals. We formulated a general frequency-domain description of EO detection by in-plane isotropic EO crystals, which holds regardless of the frequency. Based on this description, the polarization of THz waves can be derived by analyzing EO sampling signals measured with two orthogonal configurations of the in-plane isotropic EO crystals as well as typical (111) zinc-blende EO crystals. In addition, we experimentally demonstrated that the frequency-dependent polarizationof THz waves can be reproducibly retrieved using three EO crystals with different crystal symmetries and with different phase matching conditions. Our description provides essential information for practical polarization sensing in the THz frequency range as well as in the mid-infrared range.