Generation of high-energy narrowband terahertz pulses in semiconductor crystals with artificial sign modulation of nonlinear susceptibility

The new scheme for multicycle THz pulse generation by optical rectification (OR) in phase mask covered semiconductor nonlinear materials will be developed and implemented. The use of multi-slit phase mask (PM) leads to the formation of a structure with artificial periodic signmodulated of nonlinear susceptibility (SMNS). To the best of our knowledge, this is the first application of phase mask for THz generation in semiconductors. The THz generation in artificial periodic SMNS structures based on ZnTe, GaP, and GaAs will be theoretically and experimentally investigated. A comparison will be made with results for THz generation in widely used periodically poled lithium niobate and potassium titanyl phosphate (PPLN and PPKTP) crystals. According our preliminary estimations, the energy of multicycle THz pulse can reach about 50 J with relative spectral bandwidth ~ 2 %. By building the PM image in crystal with various magnifications, it is possible to change the central frequency of THz generation within one octave. In addition, it is possible to control the relative bandwidth of generation in the range of 2 – 70% by changing the aperture of the pump beam in the crystal.