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

TL;DR

This theoretical study explores the potential of isomorphs of PPKTP crystals for efficient terahertz wave generation via difference frequency generation, showing significant intensity improvements through cascaded processes.

Contribution

It introduces a theoretical analysis of THz generation using isomorphs of PPKTP crystals, highlighting enhanced efficiencies through cascaded difference frequency processes.

Findings

Cascaded difference frequency processes significantly increase THz wave intensity.

RTP, KTA, RTA, and CTA isomorphs show 2.76 to 5.27 times improvement.

Analysis of absorption, phase mismatch, and pump effects informs optimization.

Abstract

Highly efficient terahertz (THz) wave sources based on difference frequency generation (DFG) process in nonlinear optical crystals play an important role for the applications of THz wave. In order to find more novel nonlinear crystals, here we theoretically investigate the generation of THz wave using the isomorphs of periodically poled $\mathrm{KTiOPO_4}$ (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 the nonlinear crystals.