新型紫外非线性光学晶体β-YBe2B5O11的生长、表征及应用前景探索

The generation of UV coherent light has become increasingly important for their wide applications, such as semiconductor photolithography, photochemical, laser micromachining and laser processing. The best way to generate UV coherent light with solid-state lasers is through cascaded frequency conversion using nonlinear optical (NLO) crystals which are able to shorten the wavelength of light by a factor of two (or double the frequency). So far, China is a world’s leading country in UV crystal studying and fastly develop in the field..In preview study, we successful synthesized a new rare earth beryllium borate: β-YBe2B5O11 (β-YBBO). Its second harmonic generation (SHG) effect is as strong as that of KBe2BO3F2 (KBBF) and can be phase-matching. Its cut-off wavelength is 166nm. In addition, it has bulk-growth habit and is easier grown as large crystal than KBBF. Moreover, β-YBBO is non-hygroscopic and stable in the air. All of these properties show that β-YBBO is a promising UV and deep-UV NLO crystal..In this project, we will mainly study β-YBBO’s growth method and optical properties, including: (1) Select the best flux. (2) Optimize growth condition. (3) Grow the β-YBBO single crystal with centimeter size and good optical quality. (4) Measure the single crystal’s optical properties. (5) Design and manufacture YBBO UV device. (6) Achieve UV laser output by using YBBO device. After that, we will learn more about this new crystal and find out its applications as UV nonlinear optical crystal. This project is benefit to develop the application of YBBO crystal in UV region and is helpful to further develop the theory of UV crystal exploration.

非线性光学晶体是全固态激光技术中的重要基础材料。目前，工业界迫切需要输出高功率紫外与深紫外波段的全固态激光光源。而推动这一光源发展的核心技术是发展性能优异的紫外及深紫外非线性光学晶体。.项目申请人发现了一种新型非线性光学晶体β-YBe2B5O11 (β-YBBO)。前期研究结果显示其与KBe2BO3F2 (KBBF)的非线性效应相当，紫外截止边为166nm，较KBBF有更佳的生长习性。不潮解，物化性能稳定。本项目拟深入研究YBBO相图，优化单晶生长工艺，表征光学性能，设计、制作原型器件，并通过β-YBBO实现紫外波段的倍频激光输出。预计将实现以下目标：发展一种新型的、具有自主产权的紫外非线性光学晶体，探索其作为Nd:YAG激光的三倍频、四倍频，甚至六倍频变频晶体的应用前景。本项目将有助于为β-YBBO晶体的实际应用提供必要的基础理论支撑，创造应用的条件。

在本项目的研究工作中，申请人用氧化锂作为助熔剂，生长出了块状β-YBBO晶体。确认其紫外截止边为166nm，粉末倍频效应为1倍的KDP，并可实现相位匹配。测量了β-YBBO的非线性系数d31=0.08pm/V, d32=0.42pm/V, d33=-0.80pm/V。β-YBBO是一种在紫外波段具有潜在应用前景的非线性光学晶体。