An investigation of terahertz response in monocrystalline 6H-SiC for electro-optic sampling
We theoretically investigate the feasibility of terahertz detection via electro-optic (EO) sampling using 6H-SiC single crystal. The frequency response is simulated based on the principle of phase-matching condition. The optical dispersion of 6H-SiC was calculated by Sellmeier equation. In collinear incidence approach, the THz detectable bandwidths are simulated by a frequency response function at different excitation wavelengths. The cut-off frequency as a function of crystal thickness is revealed. In non-collinear incidence approach, the phase-matching condition can be achieved by using a silicon prism to couple the THz radiation into 6H-SiC single crystal. The crossing angle between THz radiation and incident optical beam is subject to the THz dispersion of Si prism and group index of 6H-SiC. The relation between THz coherence length and crossing angle is discussed. Both approaches display that 6H-SiC performs a broadband THz response for EO sampling at 515 nm. The sensitivity of EO sampling of 6H-SiC is triple times higher than GaP. In combination of the high critical breakdown field, 6H-SiC is consider to be a promising candidate for detecting high field THz radiation.
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