Narrowband terahertz generation in a plane-parallel Rb:KTP crystal using a phase mask

Abstract

A scheme for efficient generation of multi-cycle terahertz pulses by optical rectification in an artificial periodically poled rubidium (Rb)-doped potassium titanyl phosphate (Rb:PPKTP) structure is proposed. The structure consists of a multi-slit phase mask placed in front of a large-aperture Rb:KTP crystal. The developed theory predicts the THz pulse energy of 343 µJ and the efficiency of the pump-to-terahertz conversion of 0.44% for pump pulse peak intensity of 70GW/cm2 inside an aperture of 9.4×15mm2 at a crystal temperature of 85 K. The opportunity to control the THz spectral bandwidth (in the range of 1.8%∼85%) and frequency of the generation (from 0.3 to 0.8 THz) is shown. The results of the study indicate the high potential of the artificial Rb:PPKTP structure for tunable high-energy THz generation.