Terahertz-wave generating element, terahertz-wave detecting element, and terahertz time-domain spectroscopy device

Abstract

A terahertz-wave generating element includes a waveguide including an electro-optic crystal; an optical coupling member that extracts a terahertz wave, which is generated from the electro-optic crystal as a result of light propagating through the waveguide, to a space; and at least two electrodes that cause a first-order electro-optic effect in the electro-optic crystal by applying an electric field to the waveguide so as to change a propagation state of the light propagating through the waveguide. A crystal axis of the electro-optic crystal of the waveguide is set such that the terahertz wave generated by a second-order nonlinear optical process and the light propagating through the waveguide are phase-matched.

1 . A terahertz-wave detecting unit for detecting a terahertz wave by making a light from a light source enter the terahertz-wave detecting unit, comprising:
 a terahertz-wave detecting element comprising:   a waveguide including an electro-optic crystal; and   an optical coupling member that guides a terahertz wave from a space to the waveguide through which a light propagates; and   a detector that detects a beat signal based on the light and the terahertz wave.   
     
     
         2 . The terahertz-wave detecting unit according to  claim 1 , wherein the detector detects the beat signal between the light which is not coupled with the terahertz wave and the light which is coupled with the terahertz wave. 
     
     
         3 . The terahertz-wave detecting unit according to  claim 1 , wherein the terahertz-wave detecting element is of a Cerenkov phase-matching type. 
     
     
         4 . The terahertz-wave detecting unit according to  claim 1 , wherein the light is a pulsed light. 
     
     
         5 . A terahertz time-domain spectroscopy device comprising:
 a generator that generates a terahertz wave; and   a detector that detects the terahertz wave,   wherein the detector comprises the terahertz wave detecting unit according to  claim 1 .