激光自倍频晶体YbxY1-xAl3(BO3)4的研究进展

本文回顾了自倍频晶体的发展过程:从Yb3+离子的能级结构和光谱特性出发,阐述了掺Yb3+激光材料的研究前景和研究意义;简述了本课题组在YbxY1-xAl3(BO3)4晶体方面所取得的研究成果;并对YbxY1-xAl3(BO3)4晶体的未来发展作了展望.     

新型激光自倍频晶体Cr:Nd:GdCa4O(BO3)3

首次利用提拉法生长了优质铬离子敏化激光自倍频晶体Cr:Nd:GdCa4O(BO3)3(Cr:Nd:GdCOB),发现当铬离子和钕离子双掺时,由于协同效应使铬离子容易进入GdCOB晶体中,测量了Cr:Nd:GdCOB和Nd:GdCOB晶体的室温透过谱和荧光谱.Cr:Nd:GdCOB晶体在蓝紫外区比Nd:GdCOB晶体具有更强的吸收,适合于利用闪光灯泵浦.利用闪光灯泵浦分别对长度为7mm,沿最佳倍频方向(θ＝66.8°,φ＝132.6°)切割的Cr:Nd:GdCOB和Nd:GdCOB晶体进行自倍频实验.Cr:Nd:GdCOB的激发阈值为0.9J,而Nd:GdCOB的激发阈值为1.0J.在10J的输入能量时,Cr:Nd:GdCOB输出绿光能量为2.46mJ,而Nd:GdCOB输出绿光能量为1.96mJ,说明在该晶体中,铬离子对钕离子有很好的敏化作用.     

新型AgGa1-xInxSe2晶体用于CO2激光倍频研究

本实验室用布里奇曼方法成功生长出有应用前景的新型四元非线性AgGa1-xInxSe2晶体,对晶体光学透过,红外低倍显微成像,反射损耗和吸收系数进行了研究和计算.基于纯AgGaSe2和AgInSe2的Sellmeier方程,用线性内插方法计算了不同In含量的AgGa1-xInxSe2在0.9～19μm的Sellmeier色散系数并建立了Sellmeier方程.计算和描绘了Ⅰ型相位匹配CO2激光二次谐波产生的调谐曲线,并标出我们的倍频实验数据.在近似非临界相位匹配条件下,进行了TEA CO2激光10.6μm在AgGa1-xInxSe2中的倍频实验研究,并与AgGaSe2进行了比较,测量的1#AgGa1-xInxSe2相位匹配角θ及相位匹配接收外角△θext·L分别为88.2°和7.7°·cm,AgGa1-xInxSe2的倍频效率比AgGaSe2高出近3倍.     

碲镉汞晶体组分及其均匀性控制研究

本文利用碲镉汞膺二元固液T-X相图对碲镉汞晶体生长方法进行了分类研究;分析了影响碲镉汞晶体组分及其均匀性的因素,提出了存在的问题和改善的措施;认为在特定组分的固相线温度(相图中的B点)生长碲镉汞晶体是一种比较有效的方法,并报道了采用双相复合维持液相成份生长大直径40mm碲镉汞晶体组分控制研究的结果(在S≈12cm2的晶片面积上,x＝0.218±0.003).     

蓝紫光倍频材料硫氰酸汞镉晶体生长动力学和机理的研究

利用倒置相差显微镜观察了用于蓝紫光倍频的硫氰酸汞镉晶体(CdHg(SCN)4)在3;的KCl溶液中的生长形貌:在(100)面上呈现为生长直线台阶列,在锥面上呈现生长丘.在溶液循环流动的情况下测量了晶体的生长速率,发现晶体在过饱和度低于2.5;时不生长.计算了晶体不同面的界面相变熵因子.通过三者综合分析得到晶体为多二维成核生长机制.     

一种全新的非线性光学材料-金属有机配合物硫氰酸汞镉合乙二醇一甲醚(GCMTC)

本文报道了在水和乙二醇-甲醚体积比为1∶1的混合液中,用低温溶液法生长出金属有机配合物型非线性光学晶体硫氰酸汞镉合乙二醇一甲醚(GCMTC)晶体.该晶体具有较强的粉末倍频效应,用半定量的方法测定了其SHG强度约为尿素的10倍.透光范围为366～2770nm,比氰酸汞镉(CMTC)紫移了14nm.具有较稳定的物理化学性能.是一种具有潜在的应用前景的非线性光学晶体.     

GdAl3(BO3)4和Nd离子掺杂的倍频与自变频激光晶体研究

采用熔盐顶部籽晶法从K2Mo3O10-B2O3助熔剂中生长出尺寸为20 mm的优质GdAl3(BO3)4(简称GAB)和Nd3+激活的自变频激光晶体.确定了GAB晶体的透光波长范围、折射率和倍频系数随波长的变化,结果表明其在整个透光范围内均可实现相位匹配.测定了Nd3+∶GAB晶体在室温下的偏振吸收、荧光光谱和荧光寿命,进行了光谱计算,测试了晶体的自变频激光性能,实现了紫外-可见光-红外-中红外多波段激光输出.     

有机非线性倍频晶体间硝基苯甲酸*二乙醇胺的研究

本文报道了间硝基苯甲酸(m-NBA)*二乙醇胺(DEA)单晶体在不同环境下的生长习性以及对该晶体形貌的影响.测定了该晶体及两种原料的红外光谱,同时讨论了晶体的差热分析、透光波段以及初步测定了晶体的二次谐波强度.     

双掺质KTP晶体倍频效应的研究

采用激光粉末倍频法,对掺入相同浓度Nb5+离子(1;)和相同浓度Nd3+,Yb3+,Tm3+等稀土离子(3;)的KTP-K6体系中生长的Nb:Nd:KTP,Nb:Yb:KTP和Nb:Tm:KTP双掺晶体进行了粉末倍频效应测试.结果发现,3种双掺质KTP晶体的粉末倍频效应较之KTP均有所提高.     

非线性光学晶体Na3La9O3(BO3)8的高功率纳秒激光三倍频特性研究

本文对新型非线性光学晶体Na₃La₉O₃(BO₃)₈(NLBO)三倍频产生355 nm紫外纳秒激光的特性进行了研究。以重复频率10 kHz、脉冲宽度10 ns的高功率1 064 nm调Q激光器作为基频光源,采用I类相位匹配的LBO和NLBO晶体分别作为倍频晶体和三倍频晶体,获得平均输出功率152.5 mW的355 nm紫外纳秒激光输出,为目前采用NLBO晶体获得355 nm紫外激光的最高输出功率。本文还研究了NLBO晶体在实现三倍频最佳输出时晶体偏转角度随温度的变化规律,从实验角度对NLBO晶体在不同温度下的三倍频最佳相位匹配角度进行了修正。     

Investigation of the Solution Structures and Determination of the Growth Units of Cadmium Mercury Thiocyanate Crystal

To get a better understanding of the growth of cadmium mercury thiocyanate (CMTC), a promising nonlinear optical crystal, we have investigated the structures of its growth solutions by using Raman spectra. It has been found that Hg(II) ions coordinate with SCN^‐ through S atoms, forming the most stable complex of [Hg(SCN)₄]^2‐ in the solutions while Cd(II) ions bind to SCN^‐ around Hg(II) through the other end N atom. Thereby, taking [Hg(SCN)₄]^2‐ anions as centers, a network structure of Cd(II)‐N‐C‐S‐Hg(II) is formed in the solutions as in the crystal lattice. It is notably that there are other complexes, mostly the Cd(SCN)_n (n < 4) complexes, in the solutions. Therefore, the solution structure of CMTC is complicated, which is believed to contribute greatly to the difficulty of growing large single crystals. Based on the analysis of the solution structures, the reasonable growth units of CMTC are proposed.     

Preparation and Characterization of Nonlinear Optical Crystal Materials: Cadmium Mercury Thiocyanate and its Lewis Base Adducts

Cadmium mercury thiocyanate (CdHg(SCN)₄, CMTC) and its two lewis base adducts: cadmium mercury thiocyanate dimethyl‐sulphoxide (CdHg(SCN)₄(H₆C₂OS)₂, CMTD) and cadmium mercury thiocyanate glycol monomethyl ether (CdHg(SCN)₄(C₃H₈O₂), CMTG) have been discovered as nonlinear optical (NLO) crystal materials. Their structural, optical and physicochemical properties were characterized by X‐ray powder diffraction (XRPD), infrared spectroscopy, vis/UV/NIR spectra and thermal analysis. It is discovered that their transparency cutoffs lie in the UV region and CMTD crystals possess the shortest cutoff wavelength among the three crystal materials.     

Direct Growth of Aggregates on {110} Faces of Cadmium Mercury Thiocyanate Crystals

New growth phenomena ‐ direct incorporation of aggregates have been observed on the {110} faces of cadmium mercury thiocyanate CdHg(SCN)₄ crystals by atomic force microscopy. These aggregates grow in two forms: some directly cover up the steps and forms new growth layers; while others are just incorporated at the step edges. These aggregates, which are mostly oriented along [111] direction, are formed by small columnar structural units. The aggregates have the similar structure of CdHg(SCN)₄ crystals and greatly vary in nature with the variation of solution supersaturation σ and growth time t. With the increase of σ the aggregates become larger, consistent with the variation of growth units dimension with the supersaturation; and with the increase of growth time the aggregates become more structurally substantial. These observations have led to a new understanding about the crystal growth.     

Atomic Force Microscopy Studies on Growth Mechanisms and Defect Formations on {110} Faces of Cadmium Mercury Thiocyanate Crystals

Growth mechanisms and defect formations on {110} faces of cadmium mercury thiocyanate crystals grown at 30°C (σ=0.24) were investigated by using atomic force microscopy (AFM). It was found that, under this condition, spiral dislocation controlled mechanism and 2D nucleation mechanism operates simultaneously and equally during growth, which is completely different from the traditional 2D nucleation and dislocation source controlled mechanisms. A number of 2D nucleus are formed at the large step terraces generated by dislocation sources, leading to the unequal growth rates of the elementary steps and thereby “step bunches” arecaused. Various defects are formed under this growth condition, which is assumed to result from the incongruence between the steps generated by different sources. A new kind of 2D defect, corresponding to one growth layer in height, was observed for the first time.     

LiB3O5晶体946nm,473nm倍频增透膜的研制

采用离子辅助沉积技术在LiB3O5晶体上制备了946nm,473nm倍频增透膜,并测量了薄膜的性质.测试结果表明, 该增透膜具有较低的剩余反射、高的环境稳定性和良好的附着力.进一步测量了薄膜在波长1064nm多脉冲辐照下的激光损伤阈值,获得了两种不同的损伤形貌,并对损伤原因作了初步的探讨.此工艺下镀制的LiB3O5晶体用于瓦级全固态蓝光激光器,获得了3.8W波长为473nm的连续蓝光输出.     

基于级联PPMgLN晶体的双倍/三倍频双波长激光器

本文演示了紧凑的绿色和近红外双色连续波激光光源,其发射波长分别为516 nm和775 nm.设计并制造了级联的周期性极化掺镁铌酸锂晶体,用于同时转换通信波长的二次谐波(SHG)和三次谐波(THG),可以在相同温度下获得绿色和近红外激光的输出.通过建立一个单程激光测量系统,在2 W泵浦功率下获得516 nm的0.15 m...     

Investigation on the Aqueous Solution for Growth of Bimetallic Thiocyanate Complex Crystal Materials

The stability of cadmium mercury thiocyanate (CMTC) crystal growth solution was mainly discussed. The effects of temperature, pH value, time and KCl concentration on CMTC crystal growth were investigated. The effects of pH value and KCl concentration on crystallization habit of CMTC were also studied. The results show that when pH value ranges from 2.5 to 3.8, the solution is relatively stable, under the condition of pH ≤ 2.0 or pH ≥ 4.0, the solution has poor stability and some powder appears. The solution becomes unstable at high temperatures. When the concentration of KCl is more than 27% there has not generated CMTC crystal in the solution, a new kind of material produced from solution. The pH value and KCl concentration affect crystalline morphology of CMTC crystal.