飞秒激光诱导光子晶体光栅的多光子效应机理及器件研究

Diffraction grating plays an irreplaceable role in major projects such as Laser-driven nuclear fusion. And the damage threshold of the diffraction grating determines the laser output capacity of the entire laser nuclear fusion devices. Developing a new method of the diffraction grating with high damage threshold plays an important role in Laser-driven nuclear fusion device and high power laser system. This project proposes a new femtosecond laser multiphoton fabrication method for the of photonic crystal grating. In the project, ultrafast dynamics and microscopic mechanism of the interaction between femtosecond laser and transparent dielectric materials, microscopic transient mechanisms of laser induced material internal microcavity structures and high-precision laser processing principle and method of microcavity will be studied in deep. The photon energy absorption, conduction and ionization mechanisms in the process of laser-induced microcavity structure will be clarified in this research. The energy deposition characteristics of laser focusing on the micro-area and the principle and method of the laser induced micro-cavity structures will be obtained. Finally, new femtosecond laser multiphoton fabrication method and technology of three-dimensional micro-cavity with accuracy controlled morphology, spatial structure and position will be explored. Breaking through the technical bottleneck of the ultra-precision manufacturing of high damage threshold three-dimensional micro-optical device, a new method of femtosecond laser multiphoton fabrication of photonic crystal grating devices will be explored and formed in the project.

衍射光栅在激光核聚变等重大工程应用中起着不可替代的作用，而衍射光栅的损伤阈值特性决定着整个激光核聚变装置的激光输出能力，发展新型的高损伤阈值衍射光栅制备方法，对于激光核聚变装置和大能量激光系统的建设具有重要的价值，但传统微加工工艺还难以制备这种三维高精密微光学元件。本项目提出一种光子晶体光栅的飞秒激光多光子制备新方法，拟通过深入研究飞秒激光与透明电介质材料作用的超快动力学与微观机理、激光诱导材料内部微腔结构的微观瞬态机制、微腔的高精度激光制备原理与方法，并在研究中逐步澄清飞秒激光诱导微腔中的光子能量吸收、传导、电离机制，获得激光聚焦微区材料能量沉积特性与激光诱导微腔结构的原理与方法，探索出三维微腔阵列形貌、空间结构和位置精确可控的飞秒激光多光子制备方法与工艺，突破高损伤阈值三维微光学器件超精密制造的技术瓶颈，探索和形成光子晶体光栅器件的飞秒激光多光子制造新方法。

衍射光栅在激光核聚变等重大工程应用中起着不可替代的作用，发展新型的高损伤阈值衍射光栅制备方法，对于激光核聚变装置和大能量激光系统的建设具有重要的价值。针对目前三维衍射光栅制备的难题，本项目开展了三维光子晶体光栅结构的器件制备和机理研究。首先利用近红外飞秒激光脉冲，通过直写诱导、瞬态相干和高速扫描等方法，在半导体、金属表面以及透明材料内部制备出了多种周期性三维光栅结构，并在理论上开展了飞秒激光诱导材料表面均匀周期性微纳结构的机理研究，探明了飞秒激光在金膜表面制备高对比度周期光栅的动力学机制。其次，开展了飞秒激光在透明介质内部诱导微孔洞的实验研究，实现了多脉冲和单脉冲两种条件下在透明介质内部诱导微孔洞及三维微孔洞阵列，并利用单脉冲诱导微孔洞序列的方式在石英玻璃内部诱导出三维周期性微孔洞序列，其制备效率较多脉冲逐点逐层制备的方式提高了4个数量级，有望成为一种透明介质内部周期微腔器件新的制备方法。最后，我们研究了飞秒激光制备大面阵纳米小孔阵列的加工方法，实验上成功在二氧化硅（SiO2）材料表面制备了特征尺寸~25nm的纳腔/孔洞和三维微透镜阵列（单元数1000, 000），并成功开发了飞秒激光压缩成像技术，期望对上述加工过程的超快光谱以及时间特性进行实时观测。