A7MIIRE2(B5O10)3系列紫外非线性光学晶体的研究进展

稀土硼酸盐非线性光学(NLO)材料由于其在激光技术领域的重要应用而备受关注,这主要是因为三价稀土离子如Y³⁺、Sc³⁺、Lu³⁺等可以有效抑制d-d和f-f电子跃迁从而扩宽化合物的透过范围,同时稀土原子与氧原子结合成畸变的多面体可增强材料的非线性光学效应。A₇M^IIRE₂(B₅O₁₀)₃系列(RE为稀土金属,A为碱金属、M为二价金属)化合物是稀土硼酸盐中一类重要的材料,其A、M以及RE位点具备灵活的占据方式,近年来得到了广泛关注。通过化学元素取代法,研究者们对该类化合物的种类进行拓展,目前已经合成出数十种属于该体系的化合物。这些化合物的截止边大多处在紫外甚至是波长小于200 nm的深紫外波段,非线性光学效应为0.4~2.1倍KDP,在紫外以及深紫外波段非线性光学领域中展现出了应用潜力。本文对其研究现状进行了总结,分析了其微观结构与光学性能之间的关系,并指出不同位点组分对材料非线性光学性能的影响,以期对此类化合物今后的发展提供参考。

Development of A7MIIRE2(B5O10)3 Series Ultraviolet Nonlinear Optical Crystals

Rare earth nonlinear optical (NLO) borates have attracted much attention due to their important applications in the field of laser technology. It is known that the trivalent rare earth ions (RE³⁺), such as Y³⁺, Sc³⁺, and Lu³⁺, usually have wide ultraviolet transmission range since their d-d and f-f electronic transitions are effectively suppressed. Meanwhile, the distorted [REO_n] polyhedra can significantly enhance the NLO effect. A₇M^IIRE₂(B₅O₁₀)₃ series (RE=rare earth, A=alkaline metal, M=divalent metal) are an important family of rare earth borates, in which A, M and RE sites can be flexibly occupied. Till now, dozens of A₇M^IIRE₂(B₅O₁₀)₃ compounds have been synthesized through chemical element substitution. Most of their transmission cut-off edges are located in the ultraviolet band, even in the deep ultraviolet band down to 200 nm, and their NLO effects are 0.4~2.1 times of KDP, showing its potential as promising NLO materials in ultraviolet/deep ultraviolet region. This article summarizes the recent progress of A₇M^IIRE₂(B₅O₁₀)₃ family by investigating the relationship between their microstructure and optical properties, from which the effects of different atomic sites on NLO properties are pointed out. This work would be beneficial to the future development of rare earth NLO borates.