光学晶体K2Al2B2O7用于全固态紫外激光器的理论研究

讨论了(KABO)晶体的折射率与群速指数随光波长参数的变化.基于非线性光学晶体的谐波理论,详细分析比较了KABO晶体倍频和三倍频的频率变换特性.得到了LD泵浦的调QNd:YAG激光器在Ⅰ类和Ⅱ类相位匹配下的倍频,三倍频、四倍频的相位匹配角、有效非线性系数、光波走离角等参量.     

双轴晶体LiB3O5和KTiOPO4的和频特性

本文综述了非线性晶体的和频（ＳＦＭ）特性。对ＬｉＢ３Ｏ５和ＫＴｉＯＰＯ４中的二次谐波产生（ＳＨＧ）和ＳＦＭ进行了数值计算并分析了相位匹配范围,主要的相位匹配参数,最佳相位匹配角θ和Х,有效非线性系数ｄｅｆｆ,走离角α和允许角△θ和△Х。还讨论了在３个主平面内ＳＦＭ的偏振特性。     

单晶AgGaSe_2红外倍频器

采用竖式布里奇曼法生长了若干优质的ф２０×８０ｍｍＡｓＧａＳｅ２单晶体。经过Ａｇ２Ｓｅ共存下退火的样品，其通光波段透过率几乎都达到反射极限。计算了Ⅰ型和Ⅱ型红外倍频器的角度调谐特性曲线，利用上述晶体制备了１０．６μｍ辐射的Ⅰ型相位匹配倍频器。在一台ＴＥＡＣＯ２激光器的１０．６μｍ信频实验中测得相位匹配角为５６．１°，接收角参数△θ·Ｌ为１．０４°·ｃｍ。     

Linear and nonlinear optical properties of some ternary selenides

The refractive indices of the ternaryA^{I}B^{III}C_{2}^{VI}semiconductors CuAlSe2, AgGaSe2, CuGaSe2, and AgInSe2have been measured over most of the transparency range of these crystals. The optical nonlinear coefficients for second-harmonic generation of AgGaSe2CuGaSe2, and AgInSe2have also been measured. Three-frequency colinear phase matching is analyzed in detail for AgGaSe2. The birefringences of the other three crystals are not sufficient to permit three-frequency colinear phase matching within the range of the measured index. The merits of AgGaSe2for nonlinear optical applications are evaluated in comparison with other promising infrared nonlinear materials.     

Single-Cycle Terahertz Pulse Generation from OH1 Crystal via Cherenkov Phase Matching

OH1 crystal is an organic nonlinear optical crystal with a large nonlinear optical constant. However, it has dispersion of refractive indices in the terahertz (THz) frequency. This limits the frequencies that satisfy the phase matching conditions for THz wave generation. In this study, we addressed the phase matching conditions for THz wave generation by combining an OH1 crystal with prism-coupled Cherenkov phase matching. We observed the generation of single-cycle THz pulses with a spectrum covering a frequency range of 3 THz. These results prove that combining prism-coupled Cherenkov phase matching with nonlinear optical crystals yields a THz wave generation method that is insusceptible to crystal dispersion.     

单发次皮秒脉冲宽度的二阶自相关法测试

理论分析非共线二次谐波转换中非共线夹角与相位匹配角、温度及波长的变化关系,综合考虑非共轴二次谐波转换中群速度延迟、色散等因素影响,合理给出入射光斑直径、两束光之间的夹角、位相匹配角、晶体尺寸等设计参数。利用非线性晶体(KDP)非共线匹配倍频效应,研制了针对皮秒脉冲测试的单发次自相关仪,并对单发次皮秒输出脉冲宽度进行测试分析。     

Linear and nonlinear optical properties of AgGaS2, CuGaS2, and CuInS2, and theory of the wedge technique for the measurement of nonlinear coefficients

The refractive indices of the ternaryA^{I}B^{III}C_{2}^{VI}semiconductors AgGaS2, CuGaS2, and CuInS2have been measured over the entire range of transparency of these crystals. The optical nonlinear coefficients for second-harmonic generation have also been determined. Three-frequency collinear phase matching is analyzed in detail for AgGaS2. The birefringences of CuGaS2and CuInS2are not large enough to permit three-frequency phase matching within the transparent regions. A parametric oscillator threshold calculation for a pump wavelength 0.89 μ, which is within the range of the GaAs injection laser, indicates that AgGaS2is promising for this application. The upconversion efficiency in AgGaS2for sum mixing of the CO2laser (lambda = 10.5 mu) with the xenon ion laser (lambda = 0.597 mu) is also calculated. The result indicates that, depending upon system requirements and the availability of high optical quality material, AgGaS2can be comparable to ZnGeP2for upconversion. In Appendix II, we present a theory of the wedge technique for the measurement of nonlinear coefficients. This theory takes into account losses and assumes a Gaussian beam geometry. Furthermore, a discussion of units in nonlinear optics is given.     

非线性光学晶体CsLiB6O10特性的研究进展

综述了国内外对非线性光学晶体CsLiB6O10的理论和实验工作。围绕着CsLiB6O10在频率变换过程中的相位匹配角、有效非线性系数、允许参量范嗣和谐波转换效率等性能进行了阐述，从而进一步说明了CsLiB6O10是一种优质的高功率紫外光学品体。     

BBO晶体Ⅱ类相位匹配光参量放大理论分析

理论研究了BBO晶体在Ⅱ类相位匹配下非共线情况时的参量放大特性。计算了在不同非共线夹角下的相位匹配角度。在增益谱分布的模拟计算中发现Ⅱ类匹配具有非常窄的增益带宽，并在其参量带宽的模拟计算中得到了证实。数值模拟了转换效率随晶体长度的变化曲线。分析了抽运光脉冲和信号光脉冲的时间不同步以及初始输入的信号光脉冲形状对转换效率的影响。选择最佳晶体长度和同步时间，最大转换效率可达到25％。研究结果表明BBO的Ⅱ类相位匹配具有非常窄的参量带宽和增益带宽，这对于窄带的激光参量放大的研究有重要意义，并拓宽了BBO晶体在光参量放大技术中的用途。     

红外非线性晶体Na2Ge2Se5非线性变频模拟计算

对红外非线性光学晶体Na2Ge2Se5的非线性性质进行了研究。计算了在主平面内倍频调谐曲线,0.946μm、1.064μm、1.1319μm泵浦情况下的倍频空间调谐曲线以及和频产生0.589μm激光的匹配曲线,并对计算结果进行了分析比较。所得结果可为Na2Ge2Se5晶体用于特定波长激光器,设计新波段提供理论依据。     

单轴晶非共线相位匹配研究

通过对单轴晶非共线相位匹配理论的分析 ,推导出相位失配梯度、接受容限角和有效非线性系数的精确表达式。以KDP晶体为例进行了非共线倍频的理论计算和实验测试。对实验结果的分析验证了非共线相位匹配理论分析和数值计算的正确性。     

CO2激光差频GaSe晶体产生太赫兹波的数值计算

以可调谐CO2激光差频非线性GaSe晶体为例,在共线相位匹配方式下,计算了oe-e和oe-o两种相位匹配方式下的角度调谐特性、有效非线性系数、走离角和允许角。结果表明:GaSe晶体可产生73.84～3 000 m的太赫兹波,且有效非线性系数为41～54 pm/V;走离角在1.771～10.63之间;所允许的最大发散角为13.95～94.7 mrad,对入射光的方向性要求较高。对于500 m以上的太赫兹波,两种匹配方式除有效非线性系数外没有大的区别。模拟结果对于开展基于激光差频技术产生太赫兹的研究具有重要的指导意义。     

Growth and characterization of 2-inch high quality β-Ga2O3 single crystals grown by EFG method

β-Ga2O3 is an ultra-wide band-gap semiconductor with promising applications in UV optical detectors,Schottky barrier diodes,field-effect transistors and substrates for light-emitting diodes.However,the preparation of large β-Ga2O3 crystals is undeveloped and many properties of this material have not been discovered yet.In this work,2-inch β-Ga2O3 single crystals were grown by using an edge-defined film-fed growth method.The high quality of the crystal has been proved by high-resolution X-ray diffraction with 19.06 arcsec of the full width at half maximum.The electrical properties and optical properties of both the unintentionally doped and Si-doped β-Ga2O3 crystals were investigated systematically.     

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1.064μm、2.05μm、2.79μm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.     

Phase-matched harmonic generation in lithium triborate (LBO)

The authors present refractive index, thermo-optic, phase-matching angle, nonlinear coefficient, absorption, and scattering data on lithium triborate (LBO) crystals. They briefly discuss the material quality of the crystals, including the results of calorimetric absorption measurements in the infrared and ultraviolet. They present a new set of refractive index values with better than fourth decimal place precision, as well as measurements of the thermo-optic parameters. The nonlinear coefficients and other frequency conversion parameters of LBO were investigated by studying the phase-matched generation of Nd:YAG harmonics. These results are summarized. The authors discuss angular and thermal bandwidths for phase matching. Finally, they compare the efficiency of LBO with that of several other frequency conversion crystals for a common commercial application-the generation of Nd:YAG harmonics     

PPLN晶体实现2m激光输出的理论分析

为了实现2m激光输出,采用周期性极化铌酸锂(PPLN)晶体用于光参变振荡(OPO)产生2m激光的方法,从PPLN晶体的Sellmeier方程出发,考虑三波相互作用需满足的动量守恒和能量守恒条件,进行了理论分析和数值计算,得到在120℃时,PPLN晶体的极化周期为31.35m的理论值;绘制出了输出波长与极化周期、输出波长与入射角的关系曲线;并从相位同步因子sinc2(Kl/2)出发,分别计算了允许角、允许周期、允许温度.结果表明,此方法不仅克服了利用双折射特性和色散特性方法带来的走离效应,而且还充分利用了晶体的最大有效非线性系数,从而理论上提高了转换效率.该理论分析为PPLN-准相位匹配-OPO输出2m激光的下一步实验奠定了基础.     

大功率CO2激光器倍频晶体综述

介绍了中红外激光的产生方式以及各种中红外激光器的特点。结合CO2激光器倍频产生中红外的优点,重点讨论了CO2激光器倍频晶体的性能。对常用的双折射相位匹配(BPM)倍频晶体和准相位匹配(QPM)倍频晶体性能进行了比较分析。展望了高功率CO2倍频激光器的发展需要解决的问题及可能的技术途径。     

CaO-SiO2-B2O3基板材料制备的研究

研究高温熔融法制备的CaO-B2O3-SiO2与溶胶凝胶法(sol-gel)法制备的CaO-B2O3-SiO2按不同比例制备的复相陶瓷,在850℃烧结温度下的晶相组成、微观结构、烧结性能、介电性能与导电浆料的匹配性.结果表明高温熔融法制备的CaO-B2O3-SiO2晶相含有大量的CaSiO3与少量的CaB2O4.添加sol-gel法制备的CaO-B2O3-SiO2后晶相无明显变化,但经SEM分析CaSiO3晶相长大,改善了体系的烧结性能与介电性能.当添加量为15.5%,在1 MHz下,可获得εr=5.80,tgδ=0.46× 10-4.     

Noncollinear interactions in parametric luminescence

A quantum mechanical perturbation treatment of optical parametric luminescence in nonlinear crystals is briefly given. The expression obtained for the emitted signal power applies to noncollinear phase-matching situations. Next, a detailed analysis of these interactions is given, with results in the form of signal wavelength versus observation angle, with fixed pump direction. The nonlinear crystal is LiNbO3and the pump is one of the lines from an argon ion laser. The effect of temperature is studied. Emphasis is on large observation angle effects, and on the singularities arising from the particular dispersion curves of the crystal. Experimental results provide a good check on noncollinear matching predictions. The far-field signal wavelength dependence on angle as measured from pump beam is approximately quadratic for small angles, and linear for the particular temperature that gives the collinear degenerate interaction. For larger angles, the law is not simple, and there is a limiting cone of directions with no matched signal outside. This cone appears brightest in far field. Applications discussed include the accurate measurement of nonlinear susceptibilities of crystals, the design of tunable optical parametric oscillators, and the measurement of refractive indices in strong absorption regions.     

常用双轴晶体连续调谐倍频时的相位匹配特性

本文讨论了常用双轴晶体ＫＴＰ、ＬＢＯ、ＫＮ在基频光波长连续调谐时的倍频相位匹配特性，给出了这三种晶体在不同波长倍频时的最佳相位匹配角的有效倍频极化系数，并纠正了以往计算中的不正确作法。