高能量超短脉冲中红外激光技术

3~5μm中红外高能量超短脉冲激光在军事和安全等领域具有重大需求。针对该波段激光发展存在能量低、系统复杂等问题，拟采用基于2μm 全固态飞秒激光泵浦OPO，再经过Fe:ZnSe类晶体放大产生中红外高能量超短脉冲调谐激光。首先系统研究Fe:ZnSe类晶体组分结构与晶体场强、声子能量、激光性能等构效关系，建立多参数协同物理模型，获得降低声子能量、减小无辐射跃迁几率、克服声子淬灭新方法；研制出适于室温运转的高质量Fe:ZnSe类晶体，突破制约中红外激光发展的晶体材料“瓶颈”；研究Fe:ZnSe类晶体和2μm激光材料的光热折射、谐波和自聚焦等非线性效应，探索锁模新机理和设计新型器件；研究色散补偿新技术；研制2μm飞秒激光器、3~5μm 参量振荡器和晶体多冲程放大器，实现中红外可调谐脉宽100fs级、M2小于2、能量100微焦级激光输出。项目成果将推动中红外超快激光技术的发展，服务于国防重大需求。

3~5μm high energy mid-infrared ultrafast laser holds much promise for the security and military field. In this project, a 2μm all-solid-state ultrafast laser will be used as the pumping for optical parametric oscillating and generate 3~5μm ultrafast seed laser, then the seed laser will be amplified by a Fe:ZnSe based amplifier and realize the high energy output. Firstly, we would carry out the systematic research of the structure-activity relationship between the components and the properties (such as crystal field strength, phonon energy, laser performance) in the kind of Fe:ZnSe crystals. Then, a physical model based on these structure-activity relationships would be set up to obtain a new method on how to reduce the phonon energy, decrease the nonradiative transition probability, and overcome the multiple phonon quenching. Finally, a kind of excellent Fe:ZnSe crystals suitable for room temperature laser operation will be developed, which would break through the “crystal material bottleneck” that restricts the development of mid-infrared laser. We would study the nonlinear effects (photorefractive effect, thermal induced birefringence effect and self-focusing effect) of the Fe:ZnSe based crystal and the gain media emits at 2μm, find the new methods for mode-locking and design new mode-locked devices; exploit new technologies for dispersion compensation; develop a 2μm ultrafast laser with an amplifier, a 3~5μm optical parametric oscillator and a Fe:ZnSe based innoslab amplifier, and finally obtain the high energy mid-infrared femtosecond tunable laser. These achievements will promote the development of high energy mid-infrared ultrafast tunable laser and meet the great demand in the military field.