High sensitivity terahertz parametric up-conversion detector based on KTP crystal

A highly sensitive terahertz parametric up-conversion detector based on KTiOPO4(KTP) crystal pumped by 1064nm laser was demonstrated in this paper. THz wave was generated in KTP crystal with a terahertz parametric oscillator (TPO), which can generate THz wave from 1.17-5.98 THz by varying the phase-matching angle between the pump and Stokes wave inside KTP crystal. THz wave and pump wave were mixed in KTP crystal to generate up-conversion signal based on stimulated parametric scattering. The up-conversion signal was amplified in another two KTP crystals based on non-collinear and collinear phase matching to improve detection sensitivity. Spectrometer and photodiode were used to measure the wavelength and pulse energy of up-conversion signal respectively. The detectable THz frequency range was 4.26-4.50 THz and 4.80-4.92 THz. The minimum detectable energy of 250 pJ was realized with dynamic range of 32 dB at 4.40 THz, and the minimum detectable energy at 4.85 THz was 9.4 pJ with dynamic range of 48 dB. All experiments were carried out under pump threshold conditions of spontaneous parametric noise generation. Compared with LiNbO3 crystal, the parametric up-conversion detection based on KTP crystal can realize high frequency range (>3 THz) THz wave detection, filling in the gaps for high-frequency detection.

Automated summary

This paper demonstrates a highly sensitive terahertz parametric up-conversion detector based on a KTiOPO4 crystal, which enables terahertz wave detection in a high-frequency range.