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On the basis of the interaction between phonons in ionic crystals with anharmonic lattice vibration, we present a laser model on acoustic nondegenerate four-wave mixing. Two beams of highfrequency ultrasound, incident on the acoustic cavity fulfilled with the medium of ionic crystal, play the role of pumping and one of the two side-band modes of the pumping frequency as an acoustic signal mode has a strong interaction with the optical cavity mode, the coupling-out of which wiIl be the light (far-infrared) output of a laser. The problem is treated with quantum-mechanics. The theory shows that there is the threshold phenomenon as usual lasers and a so called "phase-matching" condition is derived, which should be satisfied for stability of the system. 相似文献
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We present an original detailed theoretical modeling of guided-wave noncollinear acoustooptic (AO) interaction produced by a multifrequency surface acoustic wave (SAW) in planar guided-wave structures. The modeling of the multifrequency AO interaction is based on a modified version of the coupled-mode theory. The first- and third-order diffraction efficiency and optimum dynamic range of the Bragg cell have been calculated as a function of acoustic power, acoustic radiofrequency, and optical waveguide parameters in Y-cut Ti:LiNbO3 planar waveguides. Polynomial approximations, describing the first and third order diffraction efficiency versus normalized acoustic power in the cases of two- and three-frequency interactions, are derived and presented for the first time for arbitrarily large RF signals 相似文献
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提出一种利用准平行光干涉进行激光干扰的方案。在干涉理论分析的基础上,利用He-Ne激光实验得到2路、3路、4路的多光束准平行光干涉图像与干涉强度极大值,并仿真得出准平行光干涉图像和干涉光强分布。实验和仿真表明:准平行光干涉的图样的形状取决于光束的方向角。在某些方向角时,干涉视场的中央可出现干涉亮纹或亮斑。干涉条纹或干涉光斑之间的间距由两两光束之间的夹角所确定。在不大于0.5 mrad范围内,两两光束间夹角的实验数据与仿真数据近似一致,并且干涉亮纹或亮斑的强度极大值接近理论最大值,即2束、3束、4束准平行光的干涉强度最大值分别是单束光强的4倍、8倍、15倍。给出干扰方案的效果评估以及干扰有效性的验证。 相似文献
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带有螺旋相位分布的波束都具有轨道角动量(Orbital Angular Momentum,OAM),其螺旋相位取决于OAM态拓扑荷数。理论分析了叠加涡旋光束的相位及光场分布,然后将叠加态涡旋光束的相位分布图加载到空间光调制器上产生了多态涡旋光束,讨论了不同拓扑荷数叠加时光场衍射图的分布情况。实验结果表明,叠加态的涡旋光束光场衍射图随着叠加光束拓扑荷数的正负以及数值而呈一定规律性变化,即当叠加的两束光拓扑荷数为异号时,衍射产生的光斑数为两束光拓扑荷数绝对值之和;当叠加的两束光拓扑荷数为同号时,衍射产生的光斑数为两束光拓扑荷数之差的绝对值。通过此性质可以检验涡旋光束的拓扑荷数,为叠加涡旋光束在自由空间光复用通信系统的拓扑荷数检测提供了新的方法。 相似文献
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在自适应光学系统中,采用传统的哈特曼波前传感器只能在较小视场范围内对大气湍流进行有效校正,而以光场相机作为波前探测器具有视场大、一次曝光可获得多视角方向湍流信息等特点,可以替代传统多层共轭自适应光学(MCAO)系统中的多个波前探测器,达到简化系统,节约成本的效果。文中采用自主研发的光学系统仿真软件Seelight中的光场相机模块,结合光场数字重聚焦技术、模式法大气层析技术,复原了大视场完整波前,并搭建了自适应光学仿真系统,模拟与89单元变形镜配合实现在闭环工作模式下对大视场的大气湍流引起波前畸变的有效校正。 相似文献
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S. N. Antonov A. V. Vainer V. V. Proklov Yu. G. Rezvov 《Journal of Communications Technology and Electronics》2008,53(4):453-459
Formation of the multibeam pattern of a Bragg acoustooptical modulator in the case of diffraction by a periodically phase modulated acoustic wave is considered. The relation between the spatial spectrum of diffracted light and the spectrum of the input signal is investigated for the case of highly efficient diffraction. A technique of forming a given multibeam pattern is proposed. The technique is based on the frequency modulation of an acoustic wave by a set of multiple frequencies. The level and nature of interference distortions of the pattern that appear owing to the proximity of beams in the angular space are established for the stationary diffraction regime. The processes developing during the transition from one pattern to another are considered, and the conditions ensuring minimal distortions are formulated. The results of simulations are presented. 相似文献
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涡旋光场调控对涡旋光在激光通信、生物操控等领域的应用研究具有重要意义。为了揭示透镜球差对拉盖尔-高斯(Laguerre-Gaussian,LG)涡旋光束传输特性的影响,本文基于菲涅尔衍射理论,模拟研究了不同透镜球差系数下的LG光束聚焦场的强度、相位以及螺旋谱分布。结果表明:光学系统初级球差系数的增大恶化了LG光束聚焦场的强度分布和螺旋相位,弥散了轨道角动量(orbital angular momentum,OAM) 。由此,本文提出了一种光阑补偿方案,通过在透镜前添加大小合适的圆孔光阑,以消除透镜像差。光阑补偿后的LG光束聚焦场由星芒状空心分布恢复为空心圆环分布,OAM态保持单一稳定。本研究工作为改善透镜像差对涡旋光的传输影响提供了解决方案。 相似文献
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双路频分复用荧光共焦显微探测技术研究 总被引:1,自引:0,他引:1
报道了结合频分复用技术来提高荧光共焦生物显微探测系统探测能力的实现原理和方法。通过对双路激发光信号的载频调制,将激发光聚焦到生物样品上产生荧光信号,再通过傅里叶变换、滤波和解调制过程,最后将两路荧光信号强度随时间变化曲线进行还原。实验搭建了紫外波段激励光源的双频复用荧光共焦显微成像系统,并成功探测到了鼠神经海马细胞样品发出的双点荧光信号。频分复用共焦显微成像系统能够多通道、实时、快速地探测生物细胞荧光信号,并具有较高的时间和空间分辨率。 相似文献
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The energy loss and field distribution in a curved single-mode fibre are calculated in terms of the coupling between the fundamental (LP01) mode and the radiation field. In agreement with recent experimental results, it is found that, initially, light travels in a zigzag path around the bend, and radiation is emitted in discrete beams. 相似文献
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Tsai C.S. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1996,84(6):853-869
Acoustooptic (AO) Bragg interactions between guided optical waves and surface acoustic waves (SAW's) and the resulting AO Bragg cell modulators have evolved in integrated AO technology in recent years. A variety of hybrid multichannel integrated AO device modules including power and interferometric RF spectrum analyzers, space switches, tunable filters, frequency shifters and modulators, analog algebraic processors, programmable correlators and other multichannel device modules have been realized in common LiNbO3 substrate up to 1.0×3.7 cm 2 in maximum size. The prospects for realization of their counterparts in monolithic integrated format in a common substrate of InGaAsP material system are also significantly enhanced recently. These AO device modules have shown a high degree of modularity and suggested applications in optical information processing and communications. In the meantime, the magnetooptic (MO) Bragg interactions between guided optical waves and magnetostatic waves (MSWs) in yttrium iron garnet-gadolinium gallium garnet (YIG-GGG) waveguides have resulted in miniaturized MO Bragg cell modulators in analogy with the guided-wave AO Bragg cell modulators. Most recently the performance of such MO Bragg cell modulators has been significantly improved and the modulators have been integrated with ion-milled waveguide lenses to realize hybrid integrated MO device modules, and have been utilized to demonstrate a number of novel applications. In this paper, a review of some of these integrated AO and MO device modules and applications together with some unpublished new results are presented 相似文献
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在保偏光纤两端同一偏振方向上注入两束泵浦光,产生受激布里渊散射并激发出相干声波场,该声波场会对介质折射率进行调制,即形成布里渊动态光栅。利用该动态光栅可实现温度与应变高精度的分布式测量以及多参量的同时传感,并具有读写分离、光谱可调等优点。文章从原理上详细介绍了布里渊散射与布里渊动态光栅的产生原理,并对比分析了布里渊动态光栅在光纤传感方面的优势。针对现阶段布里渊动态光栅在布里渊光相干域与布里渊光时域中的应用进行详细综述,指出了各自的不足与改进后取得的进展。最后,对布里渊动态光栅在分布式光纤传感技术中的发展进行了总结与展望。 相似文献
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Optical integrated switching systems using collinear acoustooptic (AO) interactions for wavelength division multiplexing (WDM) systems are discussed. The AO switch module has excellent advantages compared to electrooptic switches. Optical WDM signals can be wavelength-selectively switched by frequency multiplexed surface acoustic waves. WDM switching systems are proposed as an application of this AO switch, and optical insertion loss, crosstalk, and optical frequency shift are discussed. Wavelength-selective characteristics in the AO module are established. The crosstalk from other wavelengths is found to be reduced by decreasing slightly the switching transfer efficiency. The wavelength-selective switching was experimentally demonstrated with a slab-type module of a 4-mm interaction region, where the WDM interval of 25.2 Å was realized. This wavelength interval can be decreased by increasing the interaction length 相似文献
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A new type of the Schaefer-Bergmann diffraction patterns originated from the abnormal Bragg reflection phenomenon in anisotropic media has been demonstrated using α quartz and monoclinic Pb2 MoO5 crystals. The wave-vector direction of the diffracted light has been expressed in analytical equations for the general cases in uniaxial crystals as a function of those of the incident light beam and the acoustic wave, on the basis of the simple pseudo momentum conservation relation. The shape of the abnormal patterns can be determined using the equations and the known data on the acoustic and the optical wave-vector surfaces, and calculated patterns for α quartz are in good agreement with the observed ones. The equations predict that a small difference appears in the shape of the patterns between two cases where the polarization planes of the incident optical beams are orthogonal with each other, and this fact has been well confirmed by the present experiment. 相似文献