全介质三波长消偏振平板型分光膜的设计

 利用Needle合成法与Conjugate graduate精炼法，并基于Thelen和Costich的理论选择初始膜系的材料和结构，设计了532，633和1 315 nm三波长消偏振平板型分光膜。结果表明，此膜系在(532±10), (633±10)和(1 315±10) nm范围内的偏振分离都非常小。对于532，633和1 315 nm 3个波长位置的消偏振要求，入射角的合理变化范围可以是45±2°。     

近紫外区宽角度消偏振平板分光镜

简要介绍K9玻璃为基板的用金属-介质膜系实现近紫外区宽角度消偏振平板分光镜的设计,设计波长为360～480 nm,空气中的入射角变化范围为45°±6°,膜系的反射率R和透过率T的之比的平均值为63.6%,总损耗约为10%,S偏振分量和P偏振分量的平均偏离约为1%.     

近红外双波段消偏振分光膜的设计

大角度倾斜入射时,光学薄膜表现出强烈的偏振效应。这一现象在大部分应用场合会带来系统光学性能的劣变,然而控制偏振效应的光学薄膜设计是困难的。分析了产生偏振效应的内在原因,采用由三种全介质材料构成的四层膜堆和等效层结构膜堆组合得到初始膜系,结合单纯形法和共轭梯度法的多级优化,设计了1300～1330nm和1535～1565nm两个波段范围内分光比都为1∶1的近红外双波段消偏振分光膜。结果显示,在45°入射时,在两个工作波段的s分量和p分量的反射率曲线偏振分离小,反射和透射引起的相位变化也控制在很小范围。     

基于二维结构薄膜的偏振选择相位光栅的研究

利用二维结构薄膜构建了具有偏振选择特性的新型相位光栅,借助严格耦合波分析(RCWA)方法计算了光栅各级衍射强度随入射光波长及入射角的变化,发现在垂直入射情况下,波长600—640 nm范围内,相位光栅对横向电学(TE)模主要产生0级衍射,而对横向磁学(TM)模产生±1级衍射,在波长633nm处,0级衍射光的偏振消光比为109.8,±1级衍射光的偏振消光比为334.6.利用时域有限差分方法对这种相位光栅的偏振分束现象进行了模拟,偏振分离角在玻璃基板内可以达到10°左右,最后模拟了入射角为23°时光栅对不同偏     

近红外消偏振分光膜设计近红外消偏振分光膜设计

大角度倾斜入射时,光学薄膜表现出强烈的偏振效应。入射光S分量和P分量的反射率和透射率曲线,以及反射或透射引起的两个分量的相位变化都不再相同,彼此有一定的偏振分离。通过对产生偏振效应内在原因的分析,采用一个在近红外波段对于45倾斜入射光的S分量和P分量等效导纳非常接近的膜系结构,结合单纯形法优化算法,设计得到一个1 500～1 600 nm范围内反射率都是50％的近红外消偏振分光膜。结果显示,在45入射时,S分量和P分量的反射率曲线偏振分离小,反射和透射引起的相位变化也控制在很小范围。     

双菱体λ/4消色差相位延迟器的设计

根据菲涅尔全内反射相变理论,给出了双菱体λ/4消色差器的结构设计、性能分析和测量方法.由有效通光孔径和光线追迹设计出BK7玻璃在波长532 nm时相位延迟λ/4的双菱体的结构,用作532 nm至1 064 nm波长范围的标准λ/4相位延迟器.理论分析了入射角变化和波长变化对双菱体相位延迟的影响,当入射角变化限制在±4.3°以内时,其影响得到补偿;波长从532 nm到1 064 nm产生的误差为－0.65°.采用椭偏法中的消光技术,分别实测了双菱体在532 nm和1 064 nm波长下的相位延迟为：90.08±0.14°和88.99±0.1°,可知两不同波长产生的相位延迟误差为－1.09°.     

激光器件 化学激光器

TN248．5 2005053343 COIL用薄膜90°位相延迟高反射镜的研制=Fabrication of HR mirror with 90°phase retardance in COIL resonator [刊,中]／李刚(中科院大连化物所．辽宁,大连(116023)), 公发全…∥强激光与粒子束．-2005,17(2)．-161-163 在倍频膜系的设计基础上,优化设计出了激光45°入 射时对1315 nm和632．8nm双波长高反(HR)并在1315 nm处具有90°位相延迟的高反射镜,其基底材料为融石 英,高折射率材料为ZrO2,低折射率材料为SiO2。然后, 采用电子束蒸发手段制备了口径为900 mm的高反射位相 延迟镜。最后对该延迟镜的性能进行了测试。结果表明, 对632．8 nm波长的反射率≥95．0％,对1 315 nm波长的 反射率≥99．8％,位相延迟在90．235°～95．586°范围内。 图3表2参7(严寒)     

双折射消偏振膜的设计和制备

基于倾斜沉积薄膜材料的双折射特性,采用单一TiO2设计和制备了中心波长为632 nm的双折射消偏振膜。首先以60°和70°的沉积角度镀制了TiO2单层膜,通过单层膜的透射光谱分别拟合出两种沉积角度下薄膜对s和p偏振光的等效折射率nPH,nSH和nPL,nSL。通过对折射率的组合,实现正入射时s偏振光透射率大于p偏振光,而入射角度增大会使两者透射率差值减小,基于这一思想设计并制备了消偏振膜。分别测量了消偏振薄膜在400~800 nm波段范围内正入射及倾斜入射条件下s和p偏振光的透射光谱。入射角为60°时,s偏振光反射带宽基本与p偏振光反射带宽重合,在波长632 nm左右基本实现消偏振。结果表明,利用材料的双折射特性,可以设计和制备出倾斜入射条件下消偏振薄膜。     

薄膜对激光测距中棱镜器件选择的影响

分光棱镜是一些测距系统中的关键元件,而分光膜又是关键中的关键。采用45°与30°两种不同的分光棱镜,制备不同的分光膜。利用这两种棱镜作测距实验,发现在相同的天气和系统条件下,45°棱镜测距能力为800m;而30°棱镜测距能力为1800m。所以,在实际设计中一定要考虑分光膜的p偏振的影响。     

基于遗传算法的30.4 nm多层膜设计

阐述了用遗传算法设计周期和非周期多层膜的原理和实现过程,完成了30.4 nm Mg/SiC周期和非周期多层膜设计,研究了遗传算法中不同种群数和多层膜膜厚取值范围对优化结果的影响.计算发现,种群数的恰当选取是使算法快速达到或逼近最优解的前提,膜厚取值范围的合理选择是提高算法效率的关键.设计得到入射角10°的周期多层膜和15°~22°范围内的宽角多层膜在波长30.4 nm处的反射率依次为56.57%与39.96±0.29%,5°入射的双功能多层膜在波长30.4 nm和58.4 nm处的反射率分别为54.1%和0.1%.结果表明遗传算法也是一种很好的多层膜设计方法.     

Photodissociation effects on pulsed laser deposited silver oxide thin films: surface‐enhanced resonance Raman scattering

Temporal Raman scattering measurements with 488, 532 and 632 nm excitation wavelengths and normal Raman studies by varying the power (from 30 W/cm² to 2 MW/cm²) at 488 nm were performed on silver oxide thin films prepared by pulsed‐laser deposition. Initially, silver oxide Raman spectra were observed with all three excitation wavelengths. With further increase in time and power, silver oxide photodissociated into silver nanostructures. High‐intensity spectral lines were observed at 1336 ± 25 and 1596 ± 10 cm⁻¹ with 488 nm excitation. No spectral features were observed with 633 nm excitation. Surface‐enhanced resonance Raman scattering theory is used to explain the complex behavior in the intensity of the 1336/1596 cm⁻¹ lines with varying power of 488 nm excitation. Copyright © 2011 John Wiley & Sons, Ltd.     

无源光接入网单纤三向消偏振截止滤光片的研制

无源光接入网单纤三向技术是实现音频、视频、数据集成传输的关键技术。由于单纤三向滤波要求薄膜器件是大角度入射,因而所造成的偏振分离限制了信道的分离。在单纤三向滤光片的设计中,通过运用消偏振截止设计的方法,经过理论分析,并在莱宝APS1104机上镀膜,研制出了入射角为45°时偏振分量截止位置重合的消偏振截止滤光片,消除了偏振截止分离的影响。     

LaMn_(1-x)Fe_xO_3的结构和Raman光谱

通过柠檬酸法制备了钙钛矿型氧化物LaMn1-xFexO3(x=0,0.2,0.4,0.5,0.6,0.8,1),经XRD分析,x≤0.2时结构为六角相,x0.2时为正交相。实验测量了材料的拉曼光谱,发现650 cm-1左右的光谱峰位随成分参量x的变化而变化,在x≤0.2时,Raman峰随x增大向高频移动,x0.2时,则向低频移动。     

Polarization holographic gratings in an azobenzene side-chain liquid-crystalline polymer

Polarization holographic recording was investigated in a liquid-crystalline azobenzene side-chain polymer. A highly stable polarization holographic grating with the diffraction efficiency of 12.6% was written in the polymer film by two orthogonally linearly polarized 532 nm beams with equal intensities of 150 mW/cm². The polarization grating was studied with a 633 nm probe beam by surveying the conversion of the polarization state of the probe beam and measuring the dependence of diffraction efficiency on the polarization direction of the probe beam. It was found that the ± first-order diffraction efficiency and the polarization of the diffracted wave depended strongly on the polarization of the readout wave. The unusual diffraction properties of the recorded grating were attributed to the presence of the circular photoinduced birefringence. PACS 42.40.Ht; 42.40.Lx; 78.20.Fm     

Photodesorption from ultra-thin metal films – a comparison of SO<Subscript>2</Subscript> and NO<Subscript>2</Subscript> on Ag/Si(100)

The photochemistry of SO₂ on thin epitaxial Ag films (5–60 nm) deposited on Si(100) has been studied using laser light with the wavelengths of 266, 355, and 532 nm. SO₂ desorbs with cross sections of 1.7×10^-19,1.7×10^-20 and 2.9×10^-21 cm², respectively. The average translation energy, 〈E_trans/2k〉, is 440 K for 266 and 355 nm light, and 270 K for 532 nm light. Cross sections for a 60 nm thick Ag film are practically identical to the ones for Ag(111) as the substrate. An increase by a factor of ∼3.5 is observed when the film thickness is reduced to 5 nm for 266 and 355 nm light. No significant change is observed for 532 nm excitation. The film thickness has no significant influence on the translational energy of the photodesorbed molecules. The data are discussed in connection with the change of absorptivity of the metal film–semiconductor system. A model is put forward which takes into account the light absorption in the Si substrate and the reduced relaxation of excited electrons in Si. Modelling indicates that electrons excited in the Si substrate with energies and parallel momenta not allowed in Ag contribute to the surface chemistry after crossing the gap in the projected band structure of Ag(111). PACS 82.45.MP; 73.63.-b; 82.50.Bc     

Irradiation effects in CaF2 probed by Raman scattering

The formation conditions and dynamics of Ca colloids and point defects that appear in irradiated single crystals of CaF₂ were investigated by Raman spectroscopy. The intensity changes in the Raman spectra because of the presence of different concentrations of point defects and Ca colloids that emerged in CaF₂ after irradiation with 2.2 GeV Au ions were used to study their distribution and stability under illumination with three laser wavelengths (473, 532 and 633 nm) at different output powers (2 to 200 mW). A damage saturation at a fluence of 6 × 10¹¹ ion cm⁻² was observed. The dependence of the spectral changes on the ion fluence can be described by a core/halo damage cross‐section model. A radius of 13–18 nm was obtained for the outer (halo) cylinder, in agreement with previous swelling studies. Illuminations of irradiated samples with blue (473 nm) and green (532 nm) lasers were found to be extremely efficient in bleaching the samples, while illumination with a red (633 nm) laser did not lead to a sample recovery. This indicates that the bleaching process is governed by recombination of point defects that have to overcome an energy barrier. Typical time constants for the processes involved are presented. Copyright © 2016 John Wiley & Sons, Ltd.