非线性晶体高功率紫外损伤机理与抗损伤技术探究

项目名称： 非线性晶体高功率紫外损伤机理与抗损伤技术探究

项目编号： No.61475083

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 柳强

作者单位： 清华大学

项目金额： 78万元

中文摘要： 非线性晶体（LBO）高功率条件下紫外损伤问题是紫外激光器产业化的技术瓶颈，传统的办法是通过换点或者布儒斯特角输出不镀膜方式提高紫外激光器寿命，带来的问题是紫外激光功率在下降的过程中，光束质量也不断恶化，这对高精度微纳加工而言是致命的，因此研究非线性晶体高功率条件下紫外损伤机理，找到避免损伤的新方法，提高单点寿命是高功率紫外激光器的核心问题。本项目提出了通过Mie散射理论分析非线性晶体表面残留、微缺陷以及亚表面损伤等因素导致的电场增强效应，进而研究在高功率条件下引起非线性晶体表面损伤的机理，提出超平滑表面加工和残留去除等是提高非线性晶体表面抗损伤的重要手段，建立非线性晶体表面特征参数与紫外激光器寿命的定量关系，对于给定功率条件下的寿命指标给出非线性晶体表面加工要求，突破影响紫外激光器寿命的技术瓶颈。对于推进紫外激光器产业化具有重要的理论研究意义和实际应用价值。

中文关键词： 全固态激光器；LBO晶体；非线性晶体损伤；超平滑表面

英文摘要： Damage of nonlinear crystal (LBO) under irradiation of high power UV laser is the bottleneck of UV laser industrialization. Traditional solution to improve the UV laser life is to change the incident spot or keep the output light travel at Brewster angle with uncoated crystal surface. However, the beam quality degrades as the UV laser output power drops, which is a fatal problem in high precision mirco-nano processing. Therefore, it is the central issue of high power UV laser to study the damage mechanism of nonlinear crystal under the incidence of high UV laser, and figure out new ways to avoid the damage and thus increase the life of single spot on the crystal surface. This project based on the Mie scattering theory analyzes the effects of electric field enhancement caused by surface residue, micro defect and the subsurface damage of nonlinear crystal, and then studies the damage mechanism of nonlinear crystal surface induced by the irradiation of high power UV laser. The project puts forward new ways to improve the damage resistance of nonlinear crystal surface such as the ultra-smooth surface machining and residue removal method, establishes the quantitative relationship between the surface characteristic parameters of nonlinear crystal and the UV laser life, provides the machining requirements of the nonlinear crystal respecting to a life standard under the given UV laser power, breaks through the technical bottleneck that limits the life of UV laser. It has very important theoretical research sense and practical application value to promote the industrialization of ultraviolet laser.

英文关键词： all-state-solid laser;LBO crystal;nonlinear crystal damage;ultra-smooth surface