基于超快激光诱导量子应力的材料相变基础研究

Ultrafast laser technique, as one of the main routes for fine fabrication, has attracted broad interests in both the fields of science and industry. The technique has shown very good potentials in the microstructured materials in the fields of photon/light control, biological lab on chip, and so on. However, since the basic knowledge of ultrafast laser induced matter-light interaction at atomic level is still rather lacking, this leads to the difficulty in fine “fabrication” of materials at atomic level, and limits the controllable “full-scale” change for materials by the ultrafast laser technique. Our previous study has theoretically explore a kind of electron excitation induced quantumn stress to make GeSbTe phase change, where the electronic structure is disturbed and then the properties is modulated. In this proposal, based on the former studies, we plan to extend and comprehend the physial origin of the laser induced stress on matter phase change combined with the theoretical first-principles calculation and exprimental ultrafast Raman spectrum study. We will take the transparent optical medium materials for example, and study the relatively physical rules between ultrafast laser induced quantum stress and the phase states of matters. The research contents mainly include: the experimental demonstration of quantumn stress by ultrafast laser; first-principles calculation on equation of states for matter induced by quantumn stress; ultrafast Raman spectrum study on quantumn stress induced phase change. We expect our proposed research plan will elucidate the microscopic physical processes and mechanism on the generation of ultrafast laser-induced quantum stress, and lay an important stone for controling and designing new matter characteristics at atomic level using ultrafast laser technique.

超快激光技术作为精细加工核心手段日渐受到关注，该技术对材料微结构化已在光子调控、生化微流控等领域展现出广阔应用前景。然而，目前人们对其在物质原子尺度调控规律认识仍相当匮乏，从而难以对材料的基本物性进行更高层次的精准“加工”，制约了该技术对材料“全尺度”的可控性改造。前期我们以锗锑碲材料为例，理论预言了一种超快激光诱导的“量子应力”效应，能通过对其电子动态结构调控进而改变物性；在此基础上本项目拟通过飞秒拉曼光谱技术结合第一性原理模拟，以透明光学介质材料为例，建立超快激光诱导量子应力与该材料各相状态方程关联物理规律。具体研究内容包括，飞秒激光诱导物质量子应力的实验验证；量子应力诱导介质材料相变化及其状态方程规律的第一性原理研究；量子应力诱导材料相变的飞秒时间分辨拉曼光谱研究。通过以上工作澄清超快激光产生量子应力的微观物理过程和原子机制，为超快激光技术电子动态调控加工技术奠定理论和技术基础。

超快激光在微观尺度与材料的相互作用机制是激光微纳加工的基本支撑，但是目前对物质原子尺度调控规律认识仍相当匮乏，从而难以对材料的基本物性进行更高层次的精准“加工”。为此，本项目从理论与实验相结合的角度尝试阐明超快激光诱导的量子应力、原子受力的物理内涵及其在材料加工中的具体表现方式，结合材料特性提出可能的应用，首先，探索了应力、原子力产生的物理原理及基本规律；基于密度泛函理论的第一性原理计算计算了9种不同的半导体材料中不同激发量的电子-空穴等离子体作用下的应力，证明应力和激发量以及材料的平均形变势成正比。同时，研究了电子激发诱导原子受力的基本原理及规律，指出原子受力具有元素选择性和晶格对称性依赖。进一步，研究了电子激发诱导量子应力和原子受力对激光加工的潜在影响及应用：电子-空穴等离子体激发诱导的应力可以导致巨大的晶格膨胀，即使在超硬材料金刚石中也能诱导超过10%的膨胀率；激发诱导的原子受力可以导致材料的固态非晶化；低激发在有机无机杂化钙钛矿中可以在保持晶体结构的前提下调控晶格结构，使材料对称性提高；强激发可以导致材料发生库仑爆炸，用于制备非晶碳。最后，利用量子应力及原子受力基本规律和效应，探索新的激光加工方式并进行了各种微纳器件的加工：在亚皮秒尺度，提出通过预降温抑制热效应来进行冷加工的方案；利用晶格对称性对应力和力的影响，提出材料结构导向的新型加工方式；开发了刻蚀辅助飞秒激光加工新方法解决硬脆材料微纳加工精度、效率问题；实现了光量子光源及光操控元件的制备，完成了宽带隙、硬质材料蓝宝石和硫化锌的光学元件加工；上述成果有望为超快激光对材料基本物性进行动态调控的自由可控“裁剪加工”打下理论和实验基础，进一步提高激光微纳的加工精度和效率。项目共发表包括Nature Comms、Light Sci&App等高水平SCI论文36篇。

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