红外双波段激光滤光膜的研制

为了满足红外军用仪器的特殊要求,根据薄膜理论进行了红外双波段滤光膜的膜系设计;采用电子束真空镀膜的方法,通过对工艺参数的调整,在多光谱ZnS基底上镀制了1 064nm高反、3～5μm高透的红外双波段滤光膜.利用低能离子轰击,使膜层与基底间的应力明显减小;使用BGS 6341薄膜应力测试仪,采用渐变梯度法,测得其压应力由...     

人眼安全激光测距与红外成像滤光膜的研制

从人眼安全的角度,设计并制备了对1 064 nm激光抑制并可用于1 550 nm激光测距以及3 m～5 m波段红外成像的滤光膜。选用ZnS、YbF3作为膜料组合、多光谱ZnS作为基底,利用薄膜设计软件对薄膜进行了优化设计。膜系设计通过合理的厚度控制和膜层安排,来增强薄膜的机械强度。滤光膜的制备采用了电子束沉积技术,通过离子辅助沉积和真空退火处理技术,进一步提高滤光膜的牢固性。光谱测试表明:在1 064 nm处的透射率仅为0.5%,1 550 nm处的透过率为99.3%,3 m～5 m波段的平均透过率大于96%,经分析YbF3的折射率在薄膜沉积过程中有所提高,但是对光谱曲线影响不大;可靠性测试表明:滤光膜能够耐受恶劣的环境考验,满足使用要求。     

双通感红外日夜两用型滤光膜的研制

选取二氧化钛与二氧化硅作为薄膜材料,借助膜系设计软件优化设计膜系。采用离子源辅助沉积的真空镀膜方法,通过调整镀膜工艺参数,减少膜厚控制误差,在石英基底上成功镀制了符合使用要求的多波段滤光膜。所镀膜层在420～640 nm与近红外920～960 nm波段的平均透射比大于95%,680～880 nm和990～1100 nm波段的平均透射比小于3%,能够承受恶劣的环境测试,完全满足红外夜视摄像机的使用要求。     

卫星激光通信滤光膜的研制

为满足卫星激光通信中超高速数据传输的特殊要求,采用电子束和离子辅助沉积技术,制备了532nm、632nm和1 064nm波长处高反射,808nm和1 550nm处高透射的多波段滤光膜.选取了H4和SiO2作为高低折射率材料,通过对膜系设计曲线的不断优化,减少了灵敏层的个数,得到了相对易于制备的膜系结构;采用电子束加热蒸发方法并加以离子辅助沉积系统制备薄膜,采用光控与晶控同时监控的方法控制膜厚;通过不断调整工艺,提高了薄膜的抗激光损伤能力,减小了膜厚控制误差,提高了透射波段的透过率及反射波段的反射率,最终得到了光谱性能较好的滤光膜.该薄膜能够承受雨淋、盐雾、高低温等环境测试,满足使用要求.     

卫星激光通信滤光膜的研制

为满足卫星激光通信中超高速数据传输的特殊要求,采用电子束和离子辅助沉积技术,制备了532 nm、632 nm和1 064 nm波长处高反射,808 nm和1 550 nm处高透射的多波段滤光膜.选取了H₄和SiO₂作为高低折射率材料,通过对膜系设计曲线的不断优化,减少了灵敏层的个数,得到了相对易于制备的膜系结构;采用电子束加热蒸发方法并加以离子辅助沉积系统制备薄膜, 采用光控与晶控同时监控的方法控制膜厚;通过不断调整工艺,提高了薄膜的抗激光损伤能力,减小了膜厚控制误差,提高了透射波段的透过率及反射波段的反射率,最终得到了光谱性能较好的滤光膜.该薄膜能够承受雨淋、盐雾、高低温等环境测试,满足使用要求.     

模压硫系玻璃元件红外增透膜的研制

为满足红外探测系统无热化、高质量成像的需求,在非球面硫系玻璃基底制备3.7～4.8 μm波段增透膜.根据试验要求选取黏结层材料,提高基板与薄膜之间的附着力;利用有限元分析法通过多物理场仿真软件,将温度场与热应力场相结合建立三维模型,分析非球面薄膜的应力分布情况.根据模拟结果对沉积工艺进行优化,采用温度梯度烘烤法降低硫系玻璃基底的热应力,并采用真空原位退火法释放沉积薄膜的应力,解决非球面镜的脱膜问题.所制备的薄膜可以通过MIL-C-48497A标准中的附着力、湿度、中度摩擦等测试,并在3.7～4.8 μm波段的平均透过率为99.12％,满足红外探测系统的指标要求.     

近红外宽截止窄带滤光膜的研制

在空间光通信系统中,为满足光学系统对滤光膜的特殊要求,研制出了一种近红外宽截止窄带滤光膜,实现了降低深背景范围内杂散光干扰的要求.通过对薄膜材料特性的研究、膜系设计曲线的不断优化,得到了相对易于制备的窄带滤光膜结构;采用电子束加热蒸发及离子辅助沉积技术制备薄膜,采用光控加晶控同时监控的方法监控膜层厚度,通过不断优化工艺参量,提高中心波长处的透过率,最终成功得到了光谱性能较好的滤光膜.经光谱测试表明:所镀膜层在800~1 530nm、1 600~1 800nm波段平均透过率低于0.3%,1 565nm单点透过率高于92%,通带半带宽为18nm,满足光学系统的使用要求.     

可见与红外双波段宽带增透膜的研制

根据军用光学仪器的使用要求,在多光谱ZnS基底上镀制增透膜,要求薄膜在可见与近红外波段400～1000 nm及远红外波段7～11 μm的平均透射率均大于90%.采用电子束真空镀膜的方法并加以离子辅助沉积系统,通过选择ZnS和YbF3作为高低折射率材料,利用最新OptilLayer软件三大模块的功能辅助,调整镀膜工艺参数,改进监控方法,减少膜厚控制误差,在多光谱ZnS基底上成功镀制符合使用要求的增透膜.所镀膜层在可见与近红外波段400～1000 nm的平均透射率大于91%,远红外波段7～11μm的平均透射率大于90%,能够承受恶劣的环境测试,完全满足军用光学仪器的使用要求.     

激光／红外双波段减反射膜研究

在硫化锌、硒化锌两种基底上开展了激光／中波红外、激光／长波红外双波段减反射膜技术研究。通过采用离子辅助沉积以及镀保护膜层等方法,对膜系结构和镀制工艺进行了优化。研制的激光／红外双波段减反射膜不仅具有良好的光学性能,而且具有较强的抗恶劣环境能力,可以满足实际使用要求。     

ZnS和MgF2薄膜的离子辅助淀积

用Ar离子辅助制备了ZnS和MgF_2薄膜,依据滤光片吸潮波长漂移的测量,MgF_2膜的聚集密度大约从未轰击时的0.8上升到轰击后的0.9～0.95,实验发现,高能离子轰击(>1keV),膜层的吸收散射损耗增加,而低能离子轰击(<700eV)可以保持优良的光学性质,并显著地增加膜层的牢固度,这对于温度敏感的基底制备耐久薄膜是一个重要的应用.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.