Perfect phase matching regulation in cubic semiconductors based on linear electro-optic effect

A novel method to modulate the phase-matching (PM) condition based on the linear electro-optic (EO) effect in cubic nonlinear crystals was proposed to enhance the efficiency and broaden the PM bandwidth of terahertz generation. Taking ZnTe and CdTe crystals as examples, monochromatic terahertz waves can be difference-frequency generated (DFG) and agilely tuned under perfect PM condition over a range of 2.25 THz and 1.84 THz, respectively, which also corresponds to large allowable wavelength and divergence angle of the pump beam. Simultaneous wideband terahertz generation via optical rectification (OR) modulated by the EO effect was also investigated. It introduces an extra degree of freedom to fulfill PM condition of different excitation wavelengths and polarization states by OR, where the polarization selectivity can be optimized by controlling the applied voltage.