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A novel circular Dammann grating is proposed to generate uniform-intensity impulse rings corresponding to different diffraction orders in the far field. The intensities of the rings are determined by the coefficients of the circular sine series decomposition of the grating function. The definition of diffraction efficiency and uniformity for this novel device are described. Numerical solutions of binary phase circular Dammann gratings are presented. A binary phase three-order circular Dammann grating of pi phase depth is fabricated by an e-beam direct writing technique and is experimentally demonstrated. 相似文献
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提出了一种基于达曼光栅的动态光耦合器,通过控制装置中达曼光栅位移参量,可实现入射光束的分束或合束以及两者之间的动态转换。适当选择达曼光栅类型可实现任意N×M的动态光耦合。实验中以1550 nm光波长为例,对1×8达曼动态光耦合器进行测量,测得其实现光开关功能时插入损耗为0.43 dB,实现光分束功能时均匀性达到0.03,单路插入损耗均值为10.5 dB。该实验装置易于调节、体积小、能耗低,且关键元件达曼光栅制作工艺成熟,易于批量化生产。特别是在实现中大规模光交换阵列时,该方案就具有更明显的优越性,有实用意义。 相似文献
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The influences of various laser modes on the splitting beam effect of Dammann grating are studied in theory and by numerical simulation. The results show that fundamental mode laser resembles plane wave while high order mode laser differs from plane wave in the splitting beam effect by Dammann grating. Therefore, the fundamental mode laser is more suitable to be the light source to improve the energy efficiency in far-distance image detecting systems, such as laser image ladar, which use Dammann grating in the ilhlmination svstem. 相似文献
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We report a 2D static binary phase Dammann vortex grating that combines the features of a conventional vortex grating and a Dammann grating. This grating uniformly distributes energies among the diffraction orders, so the low-efficiency problem at higher diffraction orders of conventional vortex gratings is resolved and the detection range of the optical vortices (OVs) is greatly increased. Experimental results of OV detection using a fabricated 5×5 Dammann vortex grating are given, and the topological charge detection range from -12 to +12 is achieved. The potential applications of such gratings include transmitting, receiving, and multiplexing OV beams in optical communication systems. 相似文献
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A circular Dammann grating that can produce circular equal intensities at various orders in the far field is described. A set of parameters such as order, circular number, uniformity, and diffraction efficiency has been defined to describe the novel diffractive phase elements. Numerical solutions of binary-phase (0, pi) circular Dammann gratings are given. The results of experiments with a four-order circular Dammann grating made by a lithographic technique are presented. This novel diffractive optical element should be highly interesting in a wide variety of practical applications. 相似文献
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A novel technique for collimation testing with a circular Dammann grating is proposed. When the beam under test is incident on a one-order circular Dammann grating with limited aperture, double-humped radial rings will be generated at the back focal plane of a focusing lens. If the beam is collimated, the separation between the two rings will reach its minimal, otherwise the two rings will be apart from each other. Therefore, the degree of collimation of the tested beam can be estimated from the separation. The principle and experimental results of the method are presented. Owing to the simplicity and low cost of the method, it is a promising method for quickly checking the collimation of a laser beam. 相似文献
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In this paper we introduce a new phase type combined optical element. The element is combined with Dammann grating and Fresnel zone plate in the same substrate by microelectronics technique, hence it has splitting functions of the Dammann grating and self-focusing function of the Fresnel plate. It can produce uniform multiple images by itself. We experimentally designed and fabricated an 9x9 multiple image element, and results show that the element can realize the multiple images we require and the intensity of each image is the same. Relative error is less than 5%. 相似文献
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A novel method for obtaining a single shot multi-point high dynamic range pulse contrast measurement is presented. We use Dammann gratings to generate multiple beamlets by division of amplitude on ultrashort laser pulses. The analysis results show that this method can achieve high dynamic range in pulse contrast measurement on a single shot by using photomultiplier tube (PMT) detectors and the long working distances to minimize cross talk between channels. Some distortion of pulse shape is also analyzed detailedly with the Dammann grating and its compensation grating, which may degrade the pulse contrast measurement in some degree by pulse stretching and spectrum clipping. 相似文献
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采用逆达曼光栅将二维锁相相干的激光阵列进行相干合束并进行孔径装填是获得远场单一主瓣大功率高光束质量激光输出的一种有效技术方案,将其应用于大尺寸5×5固体激光相干阵列相干合束中,并进行了固体激光阵列合束孔径装填的理论分析和原理性验证实验,测量了系统的实际合束效率,同时进行了后焦面逆达曼光栅的加工和放置误差对合束效率影响的详细分析。实验结果表明,逆达曼光栅用于固体激光阵列相干合束是一种有效的技术方案,且可以通过调节光栅周期和傅里叶透镜焦距来适应系统对激光阵列占空比的要求。这对于开发基于逆达曼光栅相干合束的高功率高光质量的全固态激光系统具有重要的意义。 相似文献
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An efficient beam-combining technique based on aperture filling is introduced to direct virtually all the energy of a mutually coherent laser array to the far-field main lobe. A comparison between this method and the Dammann grating method for beam superposition reveals the connection between the two and suggests specific applications for each. 相似文献
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We propose a novel on-line beam diagnostic method based on single-shot beam splitting phase retrieval. The incident beam to be measured is diffracted into many replicas by a Dammann grating and then propagates through a weakly scattering phase plate with a known structure; the exiting beams propagate along their original direction and form an array of diffraction patterns on the detector plane. By applying the intensity of diffraction patterns into an iterative algorithm and calculating between the grating plane, weakly scattering plane, and detector plane, the complex field of the incident beam can be reconstructed rapidly; the feasibility of this method is verified experimentally with wavelengths of 1053 and 632.8 nm. 相似文献
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High-frequency enhancement by an optical system for superresolution of temporally restricted objects 总被引:2,自引:0,他引:2
A system for superresolution of temporally restricted objects allows one to transmit ultrawideband optical signals (objects) through a narrow aperture. Such a system was proposed, improved, and implemented for one- and two-dimensional objects. Implementing frequency-plane enhancement in this system provides the ability of spatial filtering of ultrawideband objects. A method for spatial filtering in a system for superresolution of temporally restricted objects by use of a generalized Dammann grating is suggested. An experimental demonstration of high-frequency enhancement (high-pass filtering) of one-dimensional objects is presented. 相似文献
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Inverse symmetric Dammann grating is a special grating, whose transition points are reflection symmetric about the midpoint with inverse phase offset in one period. It can produce even-numbered or odd-numbered array illumination when the phase modulations are π or a specific value. Numerical solutions optimized by the steepest-descent algorithm for binary phase and multilevel phases with splitting ratio from 1 × 4 to 1 × 14 are given. Fabrication of 1 × 6 array without the zero-order intensity and 1 × 7 array with the zero-order intensity are made from the same amplitude mask. A 6 × 6 output without the crossed zero-orders was achieved by crossing two one-dimensional 1 × 6 inverse symmetric Dammann gratings. This grating may have potential value for practical applications. 相似文献
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涡旋光束是一种携带有轨道角动量的光束,在光学扳手、光通信、旋转探测等领域具有重要的应用价值.由于轨道角动量态是涡旋光束的特征值,因此如何探测光束的轨道角动量态分布至关重要.国内外学者已经提出了多种探测涡旋光束的技术,如干涉法、衍射光栅法、多普勒分析法、超材料表面法等.这些技术中,衍射光栅测量法较为简单易行,应用较广.本综述主要介绍了几种当前利用衍射光栅测量涡旋光束轨道角动量态的主流方法,同时也介绍了如何利用衍射光栅来测量光束的轨道角动量谱. 相似文献
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A fiber Bragg grating bandpass filter with tailored refractive-index modulation is investigated. The writing method includes a position weighting technique, which provides flexible and accurate control of the index modulation along the fiber. This weighting is accomplished by adjusting the positions of a large number of overlapping subgratings to control the local grating strength. A 10-cm grating with a truncated sin(x)/x refractive-index modulation function was written and characterized with this method, showing good agreement with simulations. These types of filter are well suited for wavelength-division-multiplexing applications and can be made to have steep edges, low sidelobes, large bandwidth, and low stopband ripple. 相似文献