红外非线性光学晶体磷化硅镉研究进展

介绍了红外非线性光学材料磷化硅镉晶体的性能特点,以及其多晶合成、晶体生长和光学参量振荡的研究进展情况。最后,指出了制约着大尺寸、高光学质量CSP单晶体生长的主要原因以及研制CSP单晶体的必要性。     

有机非线性光学晶体——二苯甲酮的研究

本文首次报道了有机非线性光学材料二苯甲酮(DPK)单晶生长条件和方法。采用降温法在乙醇溶液中培养出50mm×80mm×50mm大尺寸的单晶,对单晶进行了定向形貌分析,测定了红外光谱和质谱,用紫外光谱测试了晶体的透射波段,用1064nm的Nd~(3+):YAG激光辐射晶体产生532nm的倍频光,其倍频强度近似KDP单晶。     

2,4-二硝基苯酚的二阶非线性光学性质研究

合成了二阶非线性光学材料 2 ,4 -二硝基苯酚 (DNP) ,测试了其二次谐波产生 (SHG)的强度和晶体结构。用 CNDO/S- CI程序计算了 DNP的分子二阶非线性光学系数β,结果表明 DNP的β值呈现明显的各向异性 ;引起分子二阶非线性效应的分子内电荷转移主要是从氨基指向邻位硝基。分析了 DNP的微观结构与宏观非线性光学倍频性能之间的关系。报道了 DNP晶体的生长 ,获得了尺寸为 2 1mm× 17mm× 7mm的优质 DNP晶体。     

新紫外用非线性光学晶体

1　前言近年 ,光刻和高密度多层基板的加工、DVD光盘的刻录、光造形、激光治疗和 DNA解析等许多产业、医疗领域 ,对相干紫外光源的需求增大了。固体激光器和非线性光学晶体相结合的全固态光源可以产生用半导体激光器难以振荡的紫外光。此外 ,与 Ar+激光器和受激准分子激光器等气体激光器相比 ,装置体积小、容易使用、维护费便宜。因此 ,许多领域的光源都趋向全固态化。以氧和硼为基本结构的硼酸盐系材料 ,大多数都具备 ( 1 )强的非线性 ;( 2 )吸收带窄 ;( 3)适度的双折射率等产生紫外光所不可缺少的特性。下面 ,以最受关注的硼酸盐 Nd∶…     

几种新型非线性光学晶体的性能和应用

本文介绍LBO、BBO、KTP、LAP晶体的物理、化学、机械和抗潮等方面的性质,给出了它们折射率的Sellmeier方程、非线性光学系数、几种常见波长的位相匹配的计算及测量结果。并对它们的性能进行了比较和讨论。还介绍了用这些晶体制成的非线性光学器件的性能和指标,最后介绍了LBO、BBO、KTP晶体在光学参量振荡和在“飞秒’脉宽激光测量上的应用。     

有机非线性光学晶体DAST的太赫兹发射性能

研究了DAST晶体的有效二阶非线性系数和太赫兹发射性能。实验以DAST-甲醇溶液的亚稳区范围为依据,采用溶液降温法进行DAST的生长。实验发现,降温速率越快,晶体的生长速度越快,但晶体易发生多晶转变;在晶体生长后期,采用较慢的降温速率,有利于晶体厚度的增加。经磨抛后的晶体表面粗糙度能够达到光学测试等级(微米级)要求。经测试,DAST晶片有效二阶非线性系数平均值为16.58 pm/V,实现了频率范围0.84~10 THz的太赫兹波发射,并在2.72 THz处具有最大发射强度。     

Crosslinkable organic glasses with quadratic nonlinear optical activity

In this paper, the use of a pure benzimidazole based dimethacrylic push–pull chromophore has been investigated for the preparation of thin films exhibiting quadratic nonlinear optical (NLO) properties. To stabilize these NLO properties, the chromophore orientation has been frozen in a noncentrosymmetric arrangement by cross-linking the material using thermal polymerization induced by suitable initiators. The films present a very stable quadratic optical activity up to T = 152 °C with SHG coefficient d₃₃ of 14 pm/V measured at 1.9 μm.     

高效倍频有机非线性晶体MHBA的倍频光产生

本文对新型有机材料MHBA进行了倍频转换实验,对调QNd∶YAG脉冲激光器产生的1064nm基频光的转换效率高达58.94％;同时产生了400～450nm连续可调的蓝紫光,转换效率约为6％。     

中远红外非线性晶体材料CdSe生长及光学性能研究

红外非线性晶体材料CdSe具有透光波段宽广,吸收系数低等优点,在中长波尤其是8-12μm红外波段的频率转换方面有广阔的应用前景,目前已引起国外众多科研机构的极大重视。采用高温元素反应法直接合成CdSe多晶料, 利用温度梯度熔体区熔法生长出CdSe单晶,晶体棒毛坯尺寸达Φ19×70mm;通过X射线粉末衍射、感应耦合等离子体质谱等对多晶原料进行成分分析,原料纯度可达5N;利用低倍率红外显微镜、红外分光光度计检测了晶体的基本光学性能,3-20μm波段晶体平均吸收系数α约为 0.08cm-1,品质良好,已能满足激光实验要求。     

Determination of crystal orientation in organic thin films using optical microscopy

The electrical behavior of devices based on highly crystalline thin films of organic semiconductors is inherently anisotropic. Thin film optimization requires simple and accessible means to characterize the orientation of the constituent crystals. The standard polarized light microscopy (PLM) provides a contrast between different crystallites but fails to distinguish crystals with relative orientation of 90°. In this paper, we discuss two methods that enable the unambiguous identification of crystal orientation in thin films of optically anisotropic materials: PLM with a full-wave retardation plate and differential interference contrast (DIC). The latter is standard on most microscopes and delivers images with high contrast and good color balance.As an illustration, we use DIC to extract the optical properties of highly crystalline thin films of three high-performance organic semiconductors: rubrene, 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C₈-BTBT). Building on the relation between optical properties and crystal orientation, we demonstrate how DIC characterizes the in-plane crystal orientation of these thin films. This leads to the identification of the fast growth direction of the crystal front.     

Optical Kerr shutter using organic nonlinear optical materials in capillary waveguides

Fundamental experiments conducted on optically gated optical switches using organic materials with large optical nonlinearities are reported. An optical Kerr shutter was constructed, whose main part is a long-length and miniature-core glass capillary, filled with a solution of charge transfer organic material of 4-(N,N-diethylamino)- beta -nitrostyrene (DEANST). The capillary waveguide made it possible to enlarge the medium length and to reduce the beam diameter, realizing about 10/sup 4/ times greater efficiency than the conventional CS/sub 2/ optical Kerr shutter using a 1-mm thick cell. A response time of 4 ps was observed and gating power was reduced to 10 W.<>     

非线性光学晶体材料GaSe激光参数的模拟计算

对红外非线性光学晶体GaSe的非线性性质进行了研究.计算模拟了1.064 μm、2.05 μm、2.79 μm泵浦情况下Ⅰ、Ⅱ类相位匹配情况下GaSe晶体的相位匹配角、有效非线性系数、走离角、允许角和泵浦波波长的关系.同时计算了晶体激光光参量震荡和倍频波波长和相位匹配角、有效非线性系数、走离角、允许角的关系.对计算结果进行了分析比较.所得结果对于GaSe晶体用于特定波长激光器设计新波段提供了理论依据.     

Suppression of unwanted self-focusing effects in nonlinear optical experiments using liquid crystal

It is demonstrated that undesired self-focusing of strong laser beams through a liquid crystal film can be suppressed by the application of an alternating voltage on the sample. Diffraction efficiencies greater than 10% for optically induced optical phase gratings in the liquid crystal are obtained when self-focusing has been suppressed.     

非线性晶体的纵向光学不均匀性对倍频的影响

研究了基波光强均匀分布情况下非线性晶体的纵向光学不均匀性对倍频的影响。利用耦合波方程求得晶体纵向光学不均匀性与倍频之间简明解析式和确定倍频晶体最佳长度的近似公式,并对晶体的纵向和横向光学不均匀性对倍频的影响进行了比较。