用于光导板的亚微米光栅透射衍射特性分析

提出了利用亚微米光棚制作光导板的方法,用严格耦合波理论博分析了亚微米光栅从光密介质到光疏介质的1级透射衍射效率与光栅槽深的关系,讨论在满足基底全反射条件的入射角下,对应于红、绿、蓝(红光700mn,绿光555nm,蓝光465nm)三色光的亚微米光栅(0.651μm、0.516μm、0.433μm)在导波条件下的光场衍射特性,并用实验证明在导波条件下1级衍射效率与光栅槽深关系的可靠性,给出亚微米光栅型光导板的初始结构,进行误差分析.     

多层膜沉积对光栅衬底槽形影响研究

衍射效率的高低是衡量极紫外多层膜光栅的最重要指标.为实现高衍射效率,必须发展合适的多层膜沉积方法,以确保在镀膜过程中光栅衬底的槽形不发生变化.针对极紫外波段所采用的矩形光栅衬底,对其镀膜过程中的槽形变化进行了考察.结果表明,多层膜周期数对保持光栅槽形至关重要.对于槽深在2～5 nm的极浅槽深矩形光栅,为确保光栅槽形不发...     

亚波长光栅用于实现宽光谱消色散1/4波片的研究

基于严格耦合波理论 ,分析了共振区域矩形位相光栅的衍射特性 :位相延迟与光栅周期、占空比、槽深的关系 ,并设计出在 40 0～ 80 0nm范围内的消色散 1/4波片光栅 ,可以实现较为平坦的衍射效率和位相延迟曲线 ,其中位相延迟可保持在 90°左右 ,最大偏差小于 9% ,达到甚至优于普通二元复合消色散波片。通过对加工及安装误差的讨论 ,得到了影响消色散波片光栅性能的主要加工误差是槽深误差和占空比误差。     

镀铬基片全息光栅光刻胶掩模槽形参量光谱检测方法

为了检测全息光栅掩模槽形,运用严格耦合波理论(RCWT)分析镀铬基片光栅光刻胶掩模反射0级衍射效率光谱曲线与槽形参量的关系。测量了400~700 nm波长范围内60°入射角条件下的镀铬基片全息光栅光刻胶掩模反射0级衍射效率光谱曲线。将实验曲线与不同槽形参数对应理论曲线相减、求标准差进行匹配,标准差最小者为匹配结果,从而找到被测掩模的槽深和占宽比(光栅齿宽占光栅周期的百分比)。结果表明,该方法图形匹配速度快,误差容限大,匹配结果与电镜结果相符。对于要求同时检测矩形或接近矩形槽形的全息光刻胶光栅掩模的槽深和占宽比,该方法完全适用。     

用于光导板的亚微米光栅衍射特性研究

提出了利用亚微米光栅制作光导板的方法,用严格耦合波理论计算分析了亚微米光栅从光密介质到光疏介质的1级透射衍射效率与光栅槽深、入射角度的关系。讨论了在满足基底全反射条件的入射角时对应于R、G、B三原色光的亚微米光栅（0．651μm、0．508μm、0．405μm）在导波条件下的光场衍射特性,并用实验证明在导波条件下1级衍射效率率与光栅槽深关系的可靠性。给出亚微米光栅型光导板的初始结构,并进行了误差分析。     

与波导表面垂直等量发射的线阵全息波导光互联

报道了以玻璃为基、以光致聚合物制造透射体积输出光栅的全息波导光互联,并通过实验绘制了光栅的衍射效率与曝光时间曲线。通过控制各输出光栅的衍射效率,可实现用一束与波导表面垂直的入射光,产生6束与波导表面垂直且能量相等的出射光。输出光栅的最大衍射效率仅需趋于50%。在波长为632.8nm的红光下,测出输出光偏离表面垂直方向的角度为0.43°,输出光的相对强度的最大偏差为11%。     

电场边缘效应对液晶光栅特性的影响

建立了液晶光栅与等效矩形光栅之间的理论模型,且计算了零级衍射效率和槽深h的理论数据。将实验数据与理论模型进行比较,得到了考虑电场边缘效应时的修正系数α和槽深h的修正计算公式,通过修正公式得出了槽深h和占空比修正值Δρ的图形,最后分析了电场边缘效应对液晶光栅衍射特性的影响。当电控液晶光栅ρ=0.5:光线正入射时进行实验测试,发现由于电场边缘效应,液晶光栅偶级衍射出现,并分析了随着电压的变化,边缘效应对液晶光栅衍射效率、相位差、占空比修正值Δρ及槽深h变化的影响。     

800 nm亚波长夹层式金属偏振分束光栅

为获得高性能的偏振分束光栅,设计了一种亚波长夹层式金属光栅结构,通过严格耦合波分析和遗传算法优化出最佳光栅结构。所设计的光栅在波长为800 nm时,0级衍射级次上TM偏振波的透射率和TE偏振波的反射率分别为98%和96.5%。在波长747 nm 854 nm,以及入射角-27 27范围内,光栅的透射和反射消光比都大于20 dB,达到了高衍射效率、高消光比、宽带宽及大角度的要求,数值分析表明该光栅对周期、槽深、覆盖层厚度具有优良的工艺容差。该光栅结构简单,性能稳定,对入射光损耗低,偏振分束效果明显,在光学偏振器件、激光器系统、偏振成像等领域具有广泛的应用前景。     

锯齿槽闪耀光栅制作误差对衍射效率的影响

与矩形槽和正弦槽光栅相比,锯齿槽光栅具有高的衍射效率,可采用全息离子束刻蚀和单点金刚石车削两种方法制造。首先,介绍了这两种方法的制造误差。然后,分析了这些制造误差对用于可见近红外和长波红外成像光谱仪的光栅衍射效率的影响,指出闪耀角误差、槽顶角误差和刻刀圆弧半径是影响锯齿槽光栅衍射效率的关键因素。为制作高质量成像光谱仪用光栅奠定了理论基础和指导。     

光谱巡天科学级紫外光栅的研制

不同于国际上其他空间项目采用光栅切换的光谱获取方式,中国空间巡天望远镜采用近焦面拼接光栅的方式获取大视场、宽波段无缝光谱,波长覆盖范围为250～1000nm,光谱分辨率R≥200。国内紫外透射衍射光栅的天文应用尚在起步阶段,制作难度高,且不能从国外获得。经过多年努力,光栅性能在近期获得了较大提升。本文针对紫外光栅的科学应用性能和使用条件,分析了衍射光栅制作参数的优化,给出了衍射效率随入射角、入射光偏振态以及光栅槽形结构参数的变化规律。相关数据对在轨流量定标具有借鉴价值。通过选用不同的光栅结构参数对衍射效率特性进行分析,发现了紫外光栅峰值波长与顶角投影在每个周期上的比值之间的近似线性表达关系。本文讨论了满足科学需求的参数许可域,并将其用于控制光栅制作参数。多次试验后,光栅槽形结构参数和形状得到了精确控制,获得了性能优异的衍射光栅。制作的光栅线密度为333line/mm,闪耀角为12.51°,峰值效率波长控制在315nm,紫外波段实测峰值衍射效率为72.3%,平均效率为65.1%。该光栅的槽形、波前质量等均控制在较高水平,衍射波前质量均方根(RMS)达到0.06λ,峰谷值(PV值)达到了0...     

Fabrication of Transmission Color Filters Using Silicon Subwavelength Gratings on Quartz Substrates

We investigate theoretically and experimentally transmission color filters using silicon subwavelength gratings on quartz substrates. Each grating area is 120$mu$m-square, which is suitable pixel size for displays and multichannel detectors. In the fabrication, electron beam lithography and fast atom beam etching are used. The grating periods are 400, 350, and 440 nm for the red, green, and blue filters, respectively. The transmission spectrum obtained from a coupling between an incident light and the submicrometer periodic grating matches with human color perception. The transmittances of 71.1%, 58.1%, and 59.3% are obtained for the red, green, and blue filters, respectively.     

LiNbO3 waveguide quasi-phase-matching second harmonicgeneration devices with ferroelectric-domain-inverted gratings formed byelectron-beam scanning

The characteristics of the formation of LiNbO₃ ferroelectric-domain-inverted gratings using electron-beam scanning are examined and discussed for application to waveguide quasi-phase-matching second-harmonic-generation (SHG) devices. It is found that the domain inversion tends to occur in segmented regions, and the inversion width is thinner near the crystal surface than inside the crystal. The dependence of the SHG efficiency on the grating structure is examined theoretically. Prototype devices for green and blue light generation have been fabricated and the device performance examined. Normalized SHG efficiencies as high as 50%/W and 70%/W, respectively, are obtained in green and blue light generation devices of 3.3-mm length. The experimental results are compared with the theoretical results     

Improvement of emission efficiency and color rendering of high-power LED by controlling size of phosphor particles and utilization of different phosphors

White light can be produced by a combination of red, green and blue emitting diode chips or by the combination of a single diode chip with phosphors. Presently, more single chip white light-emitting diodes (LEDs) than multi-chip one are used because of their low cost, easily controlled circuitry, ease of maintenance and favorable luminescence efficiency. Since phosphors must be used as light converting materials in a single diode chip to obtain the desired emission, this study considers the problems encountered in using phosphors in LEDs. The proper application of phosphors in the package of LED can improve its efficiency, color rendering and thermal stability of luminescence. For example, a uniform size distribution of phosphors with red, green and blue emission helps to improve luminescence efficiency by preventing cascade excitation; the change in color with temperature can be overcome by counter-balancing red-shifting and blue-shifting phosphors; larger particles help to ensure the high efficiency of high-power LEDs, and costs can be reduced by using small particles size in low-power LED packaging because allows less phosphor to be used to obtain a particular efficiency.     

智能型植物工厂光谱监测中的光学膜设计

介绍了一种设施农业中用于光谱监测的光学膜设计,主要利用截止滤波器的组合得到了三种设施农业用光学膜——红光膜、蓝光膜及红蓝滤光膜,红、蓝光中心波长分别在 460nm和660nm,透光带宽约50nm。红、蓝光透光波段根据植物对光谱的需求设定,在实际应用中可根据需要设定其透光的中心波长及带宽。该滤光片可用于制作设施农业及农业研究中的光谱监测单元,该光谱监测单元是将特定的光学膜片置于晶硅光伏芯片上,通过测定光伏芯片的发电量来监测光学膜片预设波段的光强度。     

Triplet Harvesting in Hybrid White Organic Light‐Emitting Diodes

White organic light‐emitting diodes (OLEDs) are highly efficient large‐area light sources that may play an important role in solving the global energy crisis, while also opening novel design possibilities in general lighting applications. Usually, highly efficient white OLEDs are designed by combining three phosphorescent emitters for the colors blue, green, and red. However, this procedure is not ideal as it is difficult to find sufficiently stable blue phosphorescent emitters. Here, a novel approach to meet the demanding power efficiency and device stability requirements is discussed: a triplet harvesting concept for hybrid white OLED, which combines a blue fluorophor with red and green phosphors and is capable of reaching an internal quantum efficiency of 100% if a suitable blue emitter with high‐lying triplet transition is used is introduced. Additionally, this concept paves the way towards an extremely simple white OLED design, using only a single emitter layer.     

Toward Highly Efficient Solid‐State White Light‐Emitting Electrochemical Cells: Blue‐Green to Red Emitting Cationic Iridium Complexes with Imidazole‐Type Ancillary Ligands

Using imidazole‐type ancillary ligands, a new class of cationic iridium complexes ( 1 – 6 ) is prepared, and photophysical and electrochemical studies and theoretical calculations are performed. Compared with the widely used bpy (2,2′‐bipyridine)‐type ancillary ligands, imidazole‐type ancillary ligands can be prepared and modified with ease, and are capable of blueshifting the emission spectra of cationic iridium complexes. By tuning the conjugation length of the ancillary ligands, blue‐green to red emitting cationic iridium complexes are obtained. Single‐layer light‐emitting electrochemical cells (LECs) based on cationic iridium complexes show blue‐green to red electroluminescence. High efficiencies of 8.4, 18.6, and 13.2 cd A^?1 are achieved for the blue‐green‐emitting, yellow‐emitting, and orange‐emitting devices, respectively. By doping the red‐emitting complex into the blue‐green LEC, white LECs are realized, which give warm‐white light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.42, 0.44) and color‐rendering indexes (CRI) of up to 81. The peak external quantum efficiency, current efficiency, and power efficiency of the white LECs reach 5.2%, 11.2 cd A^?1, and 10 lm W^?1, respectively, which are the highest for white LECs reported so far, and indicate the great potential for the use of these cationic iridium complexes in white LECs.     

白光有机电致发光器件发光稳定性研究

基于红绿/蓝双发光层,制作了结构为ITO/MoO ₃(10nm)/NPB(40nm)/TCTA(10nm)/CBP:R-4B(2%):GIR1(14%,X nm)/mCP:Firpic(8%,Y nm/BCP(10nm)/Alq₃(40nm)/LiF(1nm)/Al( 100nm)的白色全磷光有机电致发光器件(OLED),通过 调节红绿发光层的厚度X与蓝光发光层的厚度Y,研究了不同发光层厚度器件发 光性能的影响。研究发现:当X 为23nm、Y为7nm时,器件的光效和色坐标都具有 很高的稳定性,在电压分别为5、 10和15V时,色坐标分别为(0.33,0.37)、(0.33,0. 37)和(0.34,0.38);在电压为 5V时,电流密度为0.674mA,亮度为158.7cd ,最大电流效率为26.87cd/A;利用电子阻 挡材料TCTA和空穴阻挡材料BCP能够显著提高载流子的复合效率。分析认为:发光层顺序 为红绿/蓝时,更有利于蓝光的出射,从而使白光的色坐标更稳定。     

Above 20% external quantum efficiency in green and white phosphorescent organic light-emitting diodes using an electron transport type green host material

Highly efficient green and white phosphorescent organic light emitting diodes were developed using a green phosphorescent host material based on phenyl substituted spirobifluorene. A high quantum efficiency of 25.3% was achieved in the green phosphorescent device and a high quantum efficiency of 21.6% was obtained in the white device with a stacked emitting structure of deep blue and red:green emitting layers.     

Photochemically Switchable Interconnected Microcavities for All-Organic Optical Logic Gate

Optical microcavities confine molecular luminescence and transfer it to a far longer distance than the conventional Förster resonant energy transfer process. Such cavity-mediated energy transfer is advantageous for use in optical circuitry. However, to realize all-organic optical circuits, optical gate operation with organic materials is indispensable. Here, all-organic optical gates consisting of polymer whispering gallery mode (WGM) resonators that work as the optical source, drain, and gate, which are interconnected with polymer microfiber, are demonstrated. Photoirradiation of the source sphere, as an optical input, triggers the blue fluorescence that transmits to the gate sphere through the fiber. The fiber interconnection enhances both the light confinement efficiency in the individual spheres and the light transmission efficiency between distant spheres. The gate sphere contains photoisomerizable fluorescent dye that converts, in its closed state, the blue emission into green light, which is again transmitted to the drain sphere through the fiber and lets the sphere emit red light as an output. This optical cascade is switched on and off upon photoisomerization of the dye in the gate sphere. Furthermore, an energy cascade equipped with two gate spheres works as an OR-type logic gate, demonstrating potential utility for the future all-organic and all-optical integrated devices.