光纤型种子注入单频宽调谐中红外OPO脉冲光源的研究

This research project plans to find new solutions to the miniaturization, narrow-bandwidth and wideband-tuning issues of OPO mid-infrared pulsed laser source based on fiber laser technology and injection-seeded technology. By utilizing the rich wavelength resources of near-infrared region fiber laser and the nonlinear frequency conversion characteristics of injection-seeded OPO, we can obtain the optimized design for the tuning ranges and combination project of pump light and injected seed light. By developing corresponding single-frequency fiber lasers of pulsed pump light and continuous-wave injected seed light, and optimizing the structure parameters and control of resonant cavity and periodically poled crystal, and realizing the efficient coupling between the injected seed light and cavity frequency, and solving the issues of OPO system broadband tuning and effective polarization state control, we build an efficient single-frequency widely tunable OPO mid-infrared pulse laser source. Obviously, executing this project plan will definitely establish a solid theoretical and technical foundation for the development of new miniaturized single frequency widely tuning of infrared pulsed laser source, and thus, holds an remarkable significance in both scientific research and technological progress.

本项目拟基于光纤激光技术和单频种子注入技术，解决OPO光源的小型化、单频和宽带调谐等问题，发展小型化光纤型单频宽调谐OPO中红外脉冲激光源。利用光纤激光器在近红外波段的丰富波长资源以及种子注入OPO非线性频率变换的特性，设计泵浦光和注入种子光调谐组合优化方案；通过研制相应的脉冲泵浦源和连续波种子源单频光纤激光器，提出周期极化晶体和谐振腔结构参数优化设计与调控方案，并解决注入种子光与腔频之间的高效耦合、OPO系统宽带调谐以及光纤传输偏振态的有效控制问题，构建高效单频宽带连续调谐的OPO中红外脉冲激光光源。通过本项研究，将为新型小型化便携式单频宽调谐脉冲中红外激光光源的发展奠定理论与技术基础，具有极其重要的科学意义和实用价值。

光纤激光器和光纤放大器不仅具有体积小、重量轻、以及散热性能好等优点，而且光纤激光光斑小、亮度高、光束质量好，此外，近红外波段丰富的波长资源使光纤激光可调谐范围宽，光纤放大器的放大带宽宽。因此利用光纤激光光源为泵浦源，可实现中红外光学参量振荡（Optical parametric oscillator, OPO）激光源的小型化、宽调谐和高效运转，但是却存在着单个光纤激光器调谐范围有限，单频运转困难等缺点。本项目中提出利用光纤激光与传输技术，并采用种子注入单频技术构建中红外OPO系统，实现中红外单频激光宽调谐输出。.首先采用种子注入环形腔结构方案研究了宽调谐单频脉冲光纤激光泵浦源，利用温度控制稳频封装等方式解决了单频脉冲光纤激光源的单纵模稳定输出问题，并通过优化放大器结构方案，解决了单频脉冲光纤激光的功率提升问题，实现了脉冲泵浦源的单纵模稳定输出，最终获得了线宽约1.5MHz，边模抑制比约50dB，平均功率大于9W，单脉冲能量大于100uJ的窄线宽泵浦脉冲激光输出；接着研究了单频连续波光纤激光技术，实现了OPO系统种子激光源2kHz的线宽输出，同时研制了光纤光栅波长调谐器件，实现了OPO系统泵浦源与种子激光源的波长调谐；研究了基于种子注入的光学参量振荡OPO非线性频率变换特性，提出了满足中红外种子注入OPO激光源宽调谐要求的泵浦和种子光优化调谐组合方案；开展了光纤型种子注入单频宽调谐中红外OPO脉冲激光光源系统实验研究，解决了注入种子光与腔频之间的高效耦合、OPO系统宽带调谐以及光纤传输偏振态的有效控制问题，实现了中红外OPO激光源3308-3314nm平均功率520mW的单频宽调谐输出。通过本项研究，将为新型小型化便携式单频宽调谐脉冲中红外激光光源的发展奠定理论与技术基础，具有极其重要的科学意义和实用价值。