紫外、深紫外非线性光学晶体的最新进展

深紫外相干光源对于光刻技术、光电子能谱仪、激光精密机械加工等均具有十分重要的意义.本文将系统地阐述可产生深紫外谐波光输出的非线性光学晶体是如何被发现的,这些晶体的基本线性、非线性光学性质和使用它们产生深紫外谐波光的方法.最后还简单介绍深紫外谐波光的几个典型例子.     

紫外、深紫外非线性光学晶体的最新研究进展

深紫外相干光源对于光刻技术、光电子能谱仪、激光精密机械加工等均具有十分重要的意义。本文系统地阐述了可产生深紫外谐波光输出的非线性光学晶体的发现、基本线性、非线性光学性质，以及用它产生深紫外谐波光的方法。最后简介了深紫外谐波光的几个实例。     

新型深紫外非线性光学晶体KBe_2BO_3F_2族的研究进展

深紫外非线性光学晶体KBe2BO3F2(KBBF)发展至今,已有将近20年的历史。首先简单回顾了KBBF化合物的发现、晶体生长以及基本光学性质,同时对KBBF族(MBe2BO3F2,M=K,Rb,Cs)的其它化合物如:RbBe2BO3F2和CsBe2BO3F2的晶体生长和其基本光学性质进行了报道,然后对这些新晶体产生深紫外谐波光输出的能力做了评估,最后介绍了利用KBBF晶体器件产生的深紫外相干光源在先进仪器等方面的应用。     

新型紫外非线性光学晶体KNa5Ca5(CO3)8的合成、表征及性能的研究

采用水热法合成出一种新型碳酸盐非线性光学晶体材料KNa₅Ca₅(CO₃)₈, 该晶体属于六方晶系, 空间群为P63mc, 晶胞参数为a=b=1.00786(4) nm, c=1.26256(8) nm, Z=2。其晶体结构可以看作是由站立的[CO₃]基团连接相邻的两个[CaCO₃]_∞层, 从而沿[010]方向形成了四种不同类型的孔洞, 在这些孔洞中填充着K、Na 和[Na_0.67Ca_0.33]原子。KNa₅Ca₅(CO₃)₈晶体的粉末倍频效应为KDP的1.2倍, 且能够在可见光区实现相位匹配。紫外-可见-近红外漫反射光谱测试结果表明其晶体具有较大的光学带隙, 大概为5.95 eV, 是具有潜在应用前景的紫外非线性光学晶体材料。此外, 第一性原理的计算结果表明, 晶体的非线性系数主要来源于CO₃基团。     

深紫外非线性晶体KBe2BO3F2的倍频转换效率

深紫外(Duv)相干光源对于光刻技术、激光微加工、激光光谱仪等均具有重要的意义.KBe2BO3F2(KBBF)晶体是目前唯一可直接倍频产生深紫外激光的非线性光学晶体.本文通过分析KBBF晶体的光学倍频特性,分别得到了Nd:YV04激光2倍频、4倍频和6倍频以及Ti:Sapphire激光4倍频输出的相关技术参数;在此基础上,详细分析了KBBF晶体用于高斯光束的Ⅰ类和Ⅱ类倍频的转换效率.结果对于KBBF晶体用于产生深紫外全固态激光(DPL)的实验研究提供了重要的理论依据.     

非线性光学活性分子的EFISH研究

非线性极化率是衡量非线性光学材料品质的主要指标之一，本文用电场诱导二次谐波方法测定了一种新型金属有机分子碘化（反式）－［１－二茂铁基－２－（Ｎ－十八烷基－４－吡啶基）乙烯］的二阶非线性极化率，研究表明该分子具有较强的非线性光学活性。     

非线性光学晶体三硼酸铋的拉曼光散射

结构分析表明非线性光学晶体三硼酸铋BiB3 O6的晶胞参数为a1=0 .7116nm ,a2 =0 .4993nm ,a3 =0 .65 0 8nm ,β =10 5 .62° ,每个初基晶胞含有二个分子。在不同几何配置下的激光拉曼光谱观察到了晶体中硼氧四面体和硼氧三角形的特征晶格振动和振动模的分裂。拉曼光谱表明晶体的内部结构有很强的各向异性 ,这就是晶体非线性光学性质的来源     

有机低分子三阶非线性光学材料

介绍了三阶非线性光学原理.根据分子结构特征对各类有机低分子三阶非线性光学材料的结构与性能关系作了评述,提出了分子设计有机三阶NLO材料的一些规律性结论.离域能小的共轭骨架,长的共轭链,吸供取代基的引入,取代基强的供电子性或吸电子性,长的吸供电子取代基之间的距离,以及良好的共平面程度等因素均有利于获得较大的三阶NLO性能.     

新型红外波段非线性光学晶体材料研究通过验收

中科院福建物构所主持的“新型红外波段非线性光学晶体材料研究”项目通过了专家的验收。该项目组针对非线性光学晶体材料发展前沿领域,开展了红外波段非线性光学晶体材料探索研究,取得了一系列创新性研究进展。他们合成了数种在中红外区透过的新型硼铌酸盐化合物,粉末非线性倍频系数为6．8-20倍KDP,采用助溶剂法研究了晶体生长。合成了数种中远红外透过的新的硫属化物,在空气中可稳定存在至700℃,初步粉末倍频效应测试表明,该类硫属化物具有非线性光学效应。     

静态紫外地球模拟器光学系统设计

静态紫外地球模拟器是一种对紫外导航敏感器进行地面标定和精度测试的设备。本文设计了一种静态紫外地球模拟器光学系统,提出大视场静态紫外地球模拟器光学系统设计方案,对光学系统的参数进行了分析,系统选用七片透镜进行设计,有效孔径为D=10 mm,焦距为f=100 mm,视场角为Φ40°。全视场相对畸变小于0.036%,MTF在50 lp/mm处大于0.7,波像差均方根值小于0.037λ,地球张角偏差??0.006 7°,达到了高精度的指标要求,满足设计要求。     

Benzothiazolium Single Crystals: A New Class of Nonlinear Optical Crystals with Efficient THz Wave Generation

Highly efficient nonlinear optical organic crystals are very attractive for various photonic applications including terahertz (THz) wave generation. Up to now, only two classes of ionic crystals based on either pyridinium or quinolinium with extremely large macroscopic optical nonlinearity have been developed. This study reports on a new class of organic nonlinear optical crystals introducing electron‐accepting benzothiazolium, which exhibit higher electron‐withdrawing strength than pyridinium and quinolinium in benchmark crystals. The benzothiazolium crystals consisting of new acentric core HMB (2‐(4‐hydroxy‐3‐methoxystyryl)‐3‐methylbenzo[d]thiazol‐3‐ium) exhibit extremely large macroscopic optical nonlinearity with optimal molecular ordering for maximizing the diagonal second‐order nonlinearity. HMB‐based single crystals prepared by simple cleaving method satisfy all required crystal characteristics for intense THz wave generation such as large crystal size with parallel surfaces, moderate thickness and high optical quality with large optical transparency range (580–1620 nm). Optical rectification of 35 fs pulses at the technologically very important wavelength of 800 nm in 0.26 mm thick HMB crystal leads to one order of magnitude higher THz wave generation efficiency with remarkably broader bandwidth compared to standard inorganic 0.5 mm thick ZnTe crystal. Therefore, newly developed HMB crystals introducing benzothiazolium with extremely large macroscopic optical nonlinearity are very promising materials for intense broadband THz wave generation and other nonlinear optical applications.     

A Rare-Earth Selenite with Unexpectedly Well-Balanced Ultraviolet Nonlinear Optical Functionality,Sc(HSeO3)3

Establishing high performance ultraviolet (UV) nonlinear optical (NLO) selenite crystals with well-balanced properties is very challenging attributable to their strong absorption for UV light. Here a rare-earth selenite, Sc(HSeO₃)₃, with excellent UV NLO properties is introduced. Sc(HSeO₃)₃ crystallizing in the polar NCS space group, Cc, features a 3D archetiture built up by interconnected ScO₆ octahedra and HSeO₃ groups. The crystal exhibits remarkably well-balanced UV-NLO functionality, namely, the shortest absorption edge (214 nm) among NLO-active selenites, wide bandgap (5.28 eV), large phase-matchable SHG response (5 × KDP), and sufficiently large birefringence (cal. 0.105 @1064 nm). Detailed DFT calculations have been performed to elucidate the structure–property relationships. This work provides a new example of discovering novel UV NLO selenite materials.     

有机低分子三阶非线性光学材料

根据分子结构特征对各类有机低分子三阶非线性光学材料结构与性能的关系作了评述。根据三阶非线性光学基本原理对有机材料三阶非线性光学效应的机理和材料的分子设计作了分析。     

A “Phase Separation” Molecular Design Strategy Towards Large‐Area 2D Molecular Crystals

2D molecular crystals (2DMCs) have attracted considerable attention because of their unique optoelectronic properties and potential applications. Taking advantage of the solution processability of organic semiconductors, solution self‐assembly is considered an effective way to grow large‐area 2DMCs. However, this route is largely blocked because a precise molecular design towards 2DMCs is missing and little is known about the relationship between 2D solution self‐assembly and molecular structure. A “phase separation” molecular design strategy towards 2DMCs is proposed and layer‐by‐layer growth of millimeter‐sized monolayer or few‐layer 2DMCs is realized. High‐performance organic phototransistors are constructed based on the 2DMCs with unprecedented photosensitivity (2.58 × 10⁷), high responsivity (1.91 × 10⁴ A W^?1), and high detectivity (4.93 × 10¹⁵ Jones). This “phase separation” molecular design strategy provides a guide for the design and synthesis of novel organic semiconductors that self‐assemble into large‐area 2DMCs for advanced organic (opto)electronics.