高效率多波长输出THz波参量源研究

THz-wave parameter sources based on stimulated polariton scattering (SPS) are with important research significance. They can output narrow linewidth and continuously tunable THz waves. Due to the low power of the traditional Stokes light seeding sources，and the difficult for achieving multi-wavelength simultaneous output，constraining the efficiency of injection-seeded THz-wave generators (is-TPGs). Multi-wavelengths simultaneous outputting for THz-wave parameter sources is also constrained. This project is based on the frequency self-selected characteristics of cross-pumped SPS. High-power multi-wavelength Stokes lights outputs under sub-ns laser pumping condition is achieved by using pulse delay technique. Pulse-delayed multi-wavelength is-TPG is constructed. Firstly, based on the SPS basic principle and the non-collinear phase matching relationship, a theoretical model of the cross-pumped SPS frequency self-selected characteristics is established. The characteristics of the frequency self-selected seeding source based on a thin-film crystal structure are experimentally studied. High-power Stokes light outputs with high efficiency, narrow linewidth and large tuning range is obtained. Study the gain characteristics of THz wave in is-TPG, and use high power seed injection to achieve high efficiency of THz wave generation. Then the gain characteristics of THz waves in is-TPG are studied. High efficiency THz-wave generation is achieved using High power seeding injection. Finally, the pulse-delayed multi-wavelength is-TPG is constructed base on pulse delay technique. The influence of pump pulse delay time on the frequency stability and generation efficiency of THz waves is studied. The experimental parameters are optimized, and finally the high-efficiency and stable multi-wavelength THz wave output is obtained. Clear key technical barriers for real-time pop measurement applications. This study provide a viable way to realize real-time spectrum measurement applications for THz-wave parametric technology.

基于晶体受激电磁耦子散射(SPS)的THz波参量源可输出窄线宽、连续可调谐的THz波，具有重要研究意义。传统Stokes光种子源功率低，不易实现多波长同时输出，制约种子注入THz波参量发生器（is-TPG）的效率，及THz波多波长同时输出的实现。本项目基于交叉泵浦SPS自选频特性，利用脉冲延时技术，实现亚ns激光泵浦下高功率多波长Stokes光输出，构建脉冲延时多波长is-TPG。首先根据SPS基本原理和非共线相位匹配关系建立交叉泵浦SPS自选频特性理论模型，利用薄片晶体结构获得高功率、窄线宽Stokes光的高效输出。然后研究is-TPG的THz波增益特性，利用高功率种子注入实现THz波高效率产生。最后构建脉冲延时多波长is-TPG，研究泵浦脉冲延时对THz波频率稳定性及产生效率的影响，最终获得高效稳定的多波长THz波输出。本研究为THz波参量技术实现实时波谱测量提供一种可行途径。

太赫兹波具有非极性分子的穿透性和指纹光谱识别特性，大多数有机/无机非金属物质在THz波段具有特征吸收峰，THz波谱测量/成像技术在生物医学、物理学、化学、天文学、材料科学和环境科学等诸多方面有着极其重要的应用。开发多波长输出的太赫兹波源推动THz波谱检测向着非扫描、实时在线检测迈进的重要环节，具有重要研究价值。本项目围绕多波长脉冲延时输出的THz波参量源开展研究，揭示了交叉泵浦SPS实现非共线相位匹配条件的限定的物理机制；研究了基于亚ns脉宽激光交叉泵浦SPS的可调谐窄线宽Stokes光的输出特性；构建了脉冲延时泵浦的太赫兹波参量振荡器，实现双波长THz波脉冲延时输出；探索了实现多波长THz波输出的技术方案。本项目的开展为THz波谱差分测量，实时THz波谱在线检测等应用技术提供技术支持，并为短脉冲激光的非线性频率变换实现相位匹配提供另一种方案参考。