High Average Power Diode-Side-Pumped Intracavity Terahertz Parametric Source Based on Stimulated Polariton Scattering in RbTiOPO4 Crystal

Zhenhua Cong,Zengguang Qin,Zhaojun Liu,Weitao Wang,Peng Wang,Jinjin Xu,Xiaohan Chen,Xingyu Zhang,Shaojun Zhang,Feilong Gao

doi:10.1109/jphot.2020.2981527

Zhenhua Cong, Zengguang Qin + Show 8 more

Open Access

https://doi.org/10.1109/jphot.2020.2981527

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Abstract

This paper reports an intracavity terahertz parametric source based on the stimulated polariton scattering in RbTiOPO4 crystal with a high repetition rate and a high average power. The side pumping for the gain medium by laser diodes is adopted to get a higher fundamental power and a larger fundamental laser beam size than those in the diode-end-pumping in order to improve the THz output power. A non-collinear convex-plane fundamental cavity is adopted so that the thermal effect can be offset in some degree and the fundamental beam size is further increased. The obtained maximum average THz output power is 367 μW at 3.88 THz when the diode pump power is 105 W and the pulse repetition frequency (PRF) is 7 kHz. The terahertz power of 367 μW is the highest ever obtained in SPS sources.

Highlights

Terahertz wave sources have received considerable attention for many applications such as material science, drug and food inspection, security checking, biomedicine, and imaging [1]–[6]
This paper reports an intracavity terahertz parametric source based on the stimulated polariton scattering in RbTiOPO4 crystal with a high repetition rate and a high average power
A non-collinear convex-plane fundamental cavity is adopted so that the thermal effect can be offset in some degree and the fundamental beam size is further increased

Summary

Introduction

Terahertz wave sources have received considerable attention for many applications such as material science, drug and food inspection, security checking, biomedicine, and imaging [1]–[6]. Stimulated polariton scattering (SPS) is an efficient nonlinear effect which can be used to generate the terahertz wave. It is a mixed second-order and third-order nonlinear process. When a sufficiently strong fundamental laser is incident in polar crystals (both infrared-active and Raman-active), a near-infrared wave (which is usually called Stokes wave) and a far-infrared wave at THz frequency are parametrically generated. The systems based on the SPS effect are usually compact and low cost, and operated at room-temperature. The generated THz radiation is highly coherent in time and space and widely frequency-tunable. In the SPS process, the fundamental, Stokes and THz waves must follow the momentum conservation and energy conservation laws [8]

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