Terahertz waves generation using the isomorphs of PPKTP crystal: a theoretical investigation

Highly efficient terahertz (THz) wave sources based on the difference frequency generation (DFG) process in nonlinear optical crystals plays an important role for the applications of THz waves. In order to find more novel nonlinear crystals, here, we theoretically investigate the generation of THz waves using the isomorphs of periodically poled KTiOPO4 (PPKTP), including periodically poled RTP, KTA, RTA and CTA. By solving the cascaded difference frequency coupled wave equations, it is found that the intensities of the THz wave generated from the cascaded difference frequency processes are improved by 5.27, 2.87, 2.82, 3.03, and 2.76 times from the non-cascaded cases for KTP, RTP, KTA, RTA and CTA, respectively. The effects of the crystal absorption, the phase mismatch, and the pump intensity are also analyzed in detail. This study might help to provide a stronger THz radiation source based on nonlinear crystals. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study theoretically investigates the generation of THz waves using isomorphs of periodically poled KTiOPO4, showing that the intensities of THz waves from cascaded difference frequency processes are significantly improved compared to non-cascaded cases.