An investigation on terahertz response in electro-optic crystals excited at 1.03 μm wavelength

Abstract

We theoretically investigate terahertz (THz) emission and detection from 〈110〉-oriented electro-optic (EO) crystals adapted for Yb-doped femtosecond pulse laser. According to the principles of phase-matching condition, the dispersion relation between optical velocity and THz pulse, THz absorption spectra, and coherence lengths of CdTe, GaP, and GaAs crystals below the phonon resonant frequency are calculated correspondingly. The optical rectification and EO sampling process of above crystals with the same thickness of 0.1 mm are simulated. As a consequence, we found that the optimal emission frequency of CdTe is at 2.65 THz, however, it reaches 6.56 THz of GaAs and 4.77 THz of GaP. With the help of frequency response function, the calculated cut-off frequency of CdTe is only 3.45 THz, while GaAs and GaP achieve 7.15 and 6.37 THz correspondingly. Finally, the EO sampling sensitivity of GaAs is higher than CdTe and GaP when the crystal’s thickness exceeds 1.58 mm. The strong THz absorption of CdTe saturates distinctly the EO sampling sensitivity with its thickness increasing.