不同方法DKDP晶体生长和损伤阈值

生长方法是影响DKDP晶体生长和光损伤阈值的一个重要因素。分别采用传统降温法和点籽晶快速生长法,利用同种原料从氘化程度为85%的溶液生长了DKDP晶体,并选取部分Ⅱ类3倍频晶片进行3倍频光损伤阈值和透过性能测试。实验表明,不同生长方法对DKDP晶体的损伤阈值以及DKDP晶体的生长速度的影响效果正好相反,即由于生长溶液过饱和度的差别,点籽晶快速生长法晶体生长速度为传统方法的10倍,但晶体损伤阈值下降了50%,且紫外波段透过性能下降明显。     

不同方法DKDP晶体生长和损伤阈值

生长方法是影响DKDP晶体生长和光损伤阈值的一个重要因素。分别采用传统降温法和点籽晶快速生长法,利用同种原料从氘化程度为85%的溶液生长了DKDP晶体,并选取部分Ⅱ类3倍频晶片进行3倍频光损伤阈值和透过性能测试。实验表明,不同生长方法对DKDP晶体的损伤阈值以及DKDP晶体的生长速度的影响效果正好相反,即由于生长溶液过饱和度的差别,点籽晶快速生长法晶体生长速度为传统方法的10倍,但晶体损伤阈值下降了50%,且紫外波段透过性能下降明显。     

不同温度生长DKDP晶体的性质

用点籽晶快速生长法在不同温度区间生长了四块氘含量60% DKDP晶体, 观察了不同温度下晶体生长过程, 同时测量了晶体的透过光谱、摇摆曲线和1053 nm激光损伤阈值。结果表明, 在高温区间晶体生长外形优于低温生长的晶体。不同温区晶体的透过光谱并无明显变化, 但是随着生长温度的降低, 晶体的结构完整性变差, 1053 nm激光损伤阈值降低。     

不同温度生长DKDP晶体的性质

用点籽晶快速生长法在不同温度区间生长了四块氘含量60%DKDP晶体,观察了不同温度下晶体生长过程,同时测量了晶体的透过光谱、摇摆曲线和1053nm激光损伤阈值。结果表明,在高温区间晶体生长外形优于低温生长的晶体。不同温区晶体的透过光谱并无明显变化,但是随着生长温度的降低,晶体的结构完整性变差,1053nm激光损伤阈值降低。     

-1不同温度生长DKDP晶体的性质

用点籽晶快速生长法在不同温度区间生长了四块氘含量60% DKDP晶体,观察了不同温度下晶体生长过程,同时测量了晶体的透过光谱、摇摆曲线和1053 nm激光损伤阈值。结果表明,在高温区间晶体生长外形优于低温生长的晶体。不同温区晶体的透过光谱并无明显变化,但是随着生长温度的降低,晶体的结构完整性变差,1053 nm激光损伤阈值降低。     

不同脉冲宽度355 nm波长激光诱导DKDP晶体损伤特性

研究了用于三倍混频的Ⅱ类DKDP晶体在35 ps,850 ps和7.6 ns三种不同脉宽355 nm波长激光作用下的损伤特性。实验对比分析了损伤阈值、概率和损伤针点形貌、尺寸和密度,并根据损伤阈值及概率得到前驱体阈值及密度。结果表明,前驱体的激光能量吸收量与脉宽线性相关。35 ps激光作用下DKDP有一种前驱体吸收激光能量形成熔融状损伤针点。850 ps激光作用下有两种前驱体吸收激光能量并产生力学破坏形成中心熔融四周断裂的损伤针点。7.6 ns激光作用下只有一种前驱体吸收激光能量,并且形成的损伤针点与850 ps对应的损伤针点有相同特征。     

生长条件对KDP 晶体激光损伤阈值的影响

 研究了各种生长条件对晶体激光损伤阈值的影响, 发现提纯原料用的EDTA对晶体的光损伤阈值没有显著的影响, 溶液陈化能够降低晶体的散射强度,从而使光损伤阈值提高。多磷酸盐阻碍晶体锥面生长, 影响晶体的生长习性, 并降低晶体的激光损伤阈值。     

生长条件对KDP 晶体激光损伤阈值的影响

研究了各种生长条件对晶体激光损伤阈值的影响, 发现提纯原料用的EDTA对晶体的光损伤阈值没有显著的影响, 溶液陈化能够降低晶体的散射强度,从而使光损伤阈值提高。多磷酸盐阻碍晶体锥面生长, 影响晶体的生长习性, 并降低晶体的激光损伤阈值。     

DKDP晶体的拉曼散射谱分析

根据空间群理论分析和指认了磷酸二氘钾晶体[K(D_xH_1-x)₂PO₄,简称DKDP]的拉曼活性晶格振动模,测量了其室温拉曼光谱。结果表明DKDP晶体的晶格振动谱主要是由D₂PO-₄阴离子团簇的内振动引起的。与H₂PO-₄阴离子稀溶液的拉曼谱和NaD₂(PO₄)₂晶体的拉曼谱比较,DKDP晶体中D₂PO-₄阴离子的四个特征内振动模可被指认为881 cm-1(ν₁),357 cm-1(ν₂),514/541 cm-1(ν₃),965 cm-1(ν₄)。     

355nm和1064nm双波长预处理对DKDP晶体损伤性质的影响

为了研究3ω预处理、3ω和1ω同时辐照预处理情况后DKDP晶体的3ω损伤特性,建立了双波长预处理和损伤测试实验系统,重点研究了双波长同时辐照预处理情况下1ω能量密度对预处理效果的影响,分析了双波长同时辐照预处理过程中的能量耦合机制。研究结果表明:双波长同时辐照预处理在提升DKDP晶体抗3ω激光损伤性能方面的效果明显好于单波长预处理;在双波长同时辐照预处理情况下,远低于自身预处理阈值的1ω参与了预处理作用过程;在相同3ω能量密度、能量阶梯的预处理策略下,1ω能量密度存在最佳值。     

Second harmonic chalcone crystal: Synthesis, growth and characterization

The novel nonlinear optical chalcone derivative (2E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.     

热退火对KDP晶体损伤阈值的影响（英）

研究了不同退火温度下磷酸二氢钾（KDP）晶体的透过光谱和损伤阈值的变化。发现热退火对晶体的透过光谱没有影响,退火温度分别为140 ℃和160 ℃时晶体的损伤阈值没有明显变化。但是在150 ℃下,晶体的损伤阈值提高了约1.4倍。实验证明150 ℃下的热退火对提高晶体的损伤阈值效果最好。     

热退火对KDP晶体损伤阈值的影响（英）

研究了不同退火温度下磷酸二氢钾（KDP）晶体的透过光谱和损伤阈值的变化。发现热退火对晶体的透过光谱没有影响,退火温度分别为140 ℃和160 ℃时晶体的损伤阈值没有明显变化。但是在150 ℃下,晶体的损伤阈值提高了约1.4倍。实验证明150 ℃下的热退火对提高晶体的损伤阈值效果最好。     

Structural,optical, thermal and mechanical characterization of an organic nonlinear optical material: 4-methyl-3-nitrobenzoic acid single crystal

Organic single crystals of 4-methyl-3-nitrobenzoic acid (4M3N) have been grown by slow evaporation solution growth technique at room temperature. The single crystal X-ray diffraction study reveals that 4M3N crystallizes in monoclinic system with space group P21/n. The crystalline perfection of the crystal was analyzed by high resolution X-ray diffraction (HRXRD) measurements. The functional groups present in 4M3N have been identified from FT-IR and FT-Raman spectra. The lower cut-off wavelength of 4M3N is found to be 404 nm and the optical band gap is calculated as 2.91 eV. The refractive index shows normal behavior with wavelength. The physio chemical changes, decomposition and stability of the 4M3N compound were established by TG-DTA studies. Vickers microhardness measurement concludes that 4M3N belongs to soft material (n=2.5) category. The LDT value is found to be higher than that of KDP and some of the important organic NLO materials. The third order nonlinear refractive index and nonlinear absorption coefficient of the 4M3N have been measured by Z-scan studies. The imaginary and real parts of the third-order susceptibility values were determined as Im χ³=9.129×10⁻¹¹ esu and Re χ³=1.4034×10⁻⁹ esu respectively. The dislocation density was calculated to be 3.0448×10⁶ cm⁻² which indicates the quality of the crystal.     

Third order nonlinear optical,spectral, dielectric,laser damage threshold,and photo luminescence characteristics of an efficacious semiorganic acentric crystal: L-Ornithine monohydrochloride

The efficient acentric L-ornithine monohydrochloride (LOMHCl), which belongs to the trait of semiorganic category and depicts nonlinear optical characteristics, was grown-up by the process of slow evaporation. The crystal structure and crystallinity of LOMHCl was established by the process of single crystal and powder X-ray diffraction. Single XRD affirm that LOMHCl crystallizes in the system of monoclinic with P2₁ as acentric space group. The examination of FTIR was done to ascertain the existence of various functional groups in LOMHCl. UV–Vis spectral analysis substantiates its optical quality and the optical constants were also assessed. Photoluminescence process elucidates its emission characteristics and its lifetime is also determined. LOMHCl discloses exquisite resistance to laser radiation having threshold up to 2.69 GW/cm². The SEM analysis highlights its surface topography. The mechanical stability has been attested by the analysis of microhardness and several mechanical parameters are also estimated. The investigation of dielectric characteristics of LOMHCl was also accomplished. The studies on second and third order nonlinearity were established by the method of Kurtz–Perry and Z-scan which facilitates its utility in the field of nonlinear optics.     

熔石英亚表面划痕激光诱导损伤阈值实验研究

用原子力显微镜和光学显微镜观测酸蚀后熔石英亚表面划痕,并根据形貌特征将其分为Boussinesq-point-force crack(BPFC)、Hertzian-conical scratch(HCS)和Plastic indent(PI)三类,测试了各类划痕的损伤阈值,讨论了激光损伤机制。结果表明锐度较大的BPFC损伤阈值不超过2.0 J/cm<>2;深度小于1 μm的 HCS阈值可达2.6 J/cm2;形变较大的PI阈值至2.8 J/cm2,形变较小的PI的激光损伤阈值与无缺陷材料相当。BPFC 和深度超过1 μm的HCS是导致熔石英损伤阈值低的主要因素。     

The effect of porosity on the laser induced damage threshold of TiO2 and ZrO2 single layer films

Monolayer ZrO₂ and TiO₂ films were prepared on BK7 glass by physical vapor deposition (PVD) and were subsequently annealed for 1 h at 300 °C. By using the transmission spectra of two samples and the envelope method, the refractive index dispersion and extinction coefficients have been calculated. Laser induced damage threshold (LIDT) measurement shows that despite slight differences between the extinction coefficients of the two samples, the LIDT parameter of the ZrO₂ film is greater than that of the TiO₂ film. This fact leads us to consider thermal conductivity as an important parameter for interpreting the LIDT difference. According to our theoretical analysis, as a consequence of increase in the number of thermal barriers along poorer film, its thermal conductivity, and hence LIDT, decreased, which is in agreement with our experimental results. The measured porosity of the two samples shows higher porosity for TiO₂ single layer, which is in agreement with atomic force (AFM) images. The gradual and smooth damage morphology of ZrO₂ observed in optical images implies higher thermal conductivity than TiO₂.     

不同波长三倍频DKDP晶体的激光损伤

采用传统降温法,利用高纯原料从氘化程度为80%的溶液生长了四方相磷酸二氘钾（DKDP）晶体,并按Ⅱ类三倍频方式切割晶体。三倍频用DKDP晶体的最大问题在于其抗光伤阈值低于KDP晶体,严重限制了激光输出的能量密度和晶体使用寿命。考察了不同波长下三倍频DKDP晶体的损伤阈值,以及激光退火效应。实验表明,激光退火对于DKDP晶体的损伤阈值有显著的提升作用,基频、倍频、三倍频的提升效果分别达到1.4,1.9,2.7倍,是改善DKDP晶体抗光伤能力的有效途径。