碳酸钙镁石家族非线性光学晶体研究进展

自倍频晶体是将激光和非线性光学效应集于一体的一类晶体,可以实现波长变换、调幅、开关、记忆等功能,被广泛应用于光电子、光通信、激光等领域。然而现有的Nd∶LiNbO₃(Nd∶LN)、Nd∶Na₃La₉O₃(BO₃)₈(Nd∶NLBO)、Nd∶La₂CaB₁₀O₁₉(Nd∶LCB)等晶体由于固有的光折变效应、二次谐波(SHG)输出功率低、光学均匀性差等缺点限制了其进一步的应用,发展新的激光自倍频晶体具有重要的意义和价值。碳酸钙镁石家族硼酸盐晶体由于具有较大的非线性光学(NLO)系数、不易潮解、优异的光学性能和机械性能等优点,近几十年来成为人们重点研究的对象。本文从晶体结构、生长方法、性能、发展趋势等方面,着重介绍了碳酸钙镁石家族REM₃(BO₃)₄(RE为稀土元素La-Lu和Y;M为Al,Ga,Sc)和La_xRE_ySc_z(BO₃)₄(RE=Gd,Y,Nd,Lu,Sm,Tb;x+y+z=3)共取代型硼酸盐非线性光学晶体。对比了不同助熔剂、气氛、方法生长的晶体的紫外(UV)截止边、光学性能、非线性性能的差异。通过改善生长工艺,进行元素掺杂等可以得到光学性能良好、非线性性能显著、有广泛市场应用前景的自倍频(SFD)晶体。

Research Progress of Huntite Family Nonlinear Optical Crystals

Self frequency doubling crystal is a kind of crystal that integrates laser and nonlinear optical effect, which can realize wavelength conversion, amplitude modulation, switch, memory and other functions, and has become widely used in photoelectronic, optical communication, laser and other fields. However, the existing crystals such as Nd∶LiNbO₃(Nd∶LN), Nd∶Na₃La₉O₃(BO₃)₈(Nd∶NLBO), Nd∶La₂CaB₁₀O₁₉(Nd∶LCB) have limited the further applications due to their inherent photorefractive effect, low second harmonic generation (SHG) output power, poor optical homogeneity and other shortcomings, so it is necessary to develop new laser self frequency doubling crystals. Due to the large nonlinear optics (NLO) coefficient, difficult to deliquesce, excellent optical, mechanical properties and so on, hunitite family borate crystals have become the focus of research in recent decades. In this paper, the crystal structure, growth methods, properties and development trend and other aspects of huntite family REM₃(BO₃)₄ (RE is rare earth elements La-Lu and Y; M is Al, Ga, Sc) and La_xRE_ySc_z(BO₃)₄(RE=Gd, Y, Nd, Lu, Sm, Tb; x+y+z=3) co-substituted borate nonlinear optical crystals are introduced emphatively. The differences of ultraviolet (UV) cut-off edge, optical properties and nonlinear properties of crystals grown by different fluxes, atmospheres and methods are compared. By improving the growth technology and doping elements, self-frequency-doubled (SFD) crystals with good optical properties, remarkable nonlinear properties and extensive market application prospects can be obtained.