共查询到20条相似文献,搜索用时 15 毫秒
1.
光折变晶体Ce:BaTiO_3中的各向同性扇形散射 总被引:1,自引:0,他引:1
用一束e偏振的激光入射到一块掺CeBaTiO3晶体上,在出射方向上观察到了相同偏振的散射光扇。测量了散射光强度、建立时间与入射光波长、入射角度、入射功率的依赖关系,以及散射光强的角分布。对实验现象进行了解释。使用一组经过简化的基于二波耦合理论的方程进行了计算。在所得结果中,散射光强的角分布与实验值定量地符合;透射光强与入射角度、波长的关系能够反映出其变化趋势。 相似文献
2.
Ce:KNSBN晶体光扇效应的入射光强度阈值特性研究 总被引:5,自引:0,他引:5
采用非同时读出条件下的两波耦合实验装置,以单束光入射Ce:KNSBN光折变晶体,系统研究了Ce:KNSBN晶体中光扇效应随入射光偏振态、入射光强度、光入射角的变化情况.结果表明异常偏振光入射晶体时光扇效应明显,且存在明显的入射光强度阈值特性,入射光强度阈值为38.2 mW/cm2;相同光入射角下,稳态光扇强度随入射光强度的增强而明显变大;对应相同的入射光强度,稳态光扇强度随光入射角θ的增大而增大,当θ为15°时到达峰值,而后随θ的增大而逐渐减小.同时对光扇效应的入射光强度阈值特性以及稳态光扇强度随入射光偏振态、入射光强度、光入射角的变化作出了相应的物理解释. 相似文献
3.
Daisuke Ishikawa Atsushi Okamoto Satoshi Honma Terumasa Ito Kohei Shimayabu Kunihiro Sato 《Optical Review》2007,14(4):246-251
In this paper, we propose all-optical multifunctional logic gates for image information using photorefractive (PR) two-wave
mixing. The optical setup is simply configured compared with the other all-optical logic gates for image information. The
XOR-, OR-, and AND-operation are all-optically performed in the same optical setup through the transitional response of the
PR medium. One can switch these logic operations simply by means of the on-off control of the signal and the pump beam illumination.
We analyze the spatial distribution of beam intensity in these logic gates using a finite-difference beam propagation method
(FD-BPM) and the crosstalk between adjoining pixels is examined from the result. We also experimentally verify that the XOR-,
OR-, and AND-gates are realized in the same optical setup. 相似文献
4.
光折变两波耦合对光扇开效应的抑制作用 总被引:4,自引:0,他引:4
以多个两波耦合(TWM)相位栅模型建立了考虑光扇开效应后的动态两波耦合方程,通过数值求解揭示了在大信号两波耦合对光扇开效应的抑制作用和在小信号下光束扇开损耗对两波耦合影响的规律,并进行了相应的实验研究。 相似文献
5.
采用两波耦合非同时读出实验装置 ,测量了掺铈钾钠铌酸锶钡 (Ce∶KNSBN)晶体两波耦合过程中的信号光和抽运光非同时打开条件下两波耦合增益的时间变化规律 ,讨论了光扇的入射光强阈值及光扇效应对两波耦合动态过程的影响。结果表明 :6 32 .8nmHe Ne激光在Ce∶KNSBN晶体中写入体光栅时 ,光扇效应存在明显的写入光强阈值特性 ,当入射光强大于 30mW /cm2 时 ,才存在强烈的光扇效应。利用修正耦合波方程对Ce∶KNSBN晶体中的两波耦合动态过程、增益随着信号光和抽运光打开时间间隔Δt的变化进行了模拟计算 ,理论模拟结果与实验测量结果基本一致 相似文献
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Kenichi Masuda Atsushi Tate Mariko Ishida Takanori Suzuki Hiroyuki Tsuda 《Optical Review》2006,13(4):184-188
We propose a beam steering type optical switch employing a phase shifter. It consists of collimating waveguide mirrors, an
arrayed-waveguide which has deep trenches incorporating polymer materials, and input/output waveguides. The incident light
is guided to the front mirror, where it is then collimated, and input to the arrayed waveguide. The number of trenches filled
with polymer linearly increases in order. The refractive index of the polymer can be controlled with temperature, and the
propagation direction of the output light from the arrayed waveguide can also be controlled. A switch with 15 waveguides in
the array has been fabricated. The chip size is about 2:5 × 9:0 mm2, the insertion loss is 10 dB, and the extinction ratio is about 10–13 dB. 相似文献
8.
A model of an optical neural network with learning ability is proposed. We numerically evaluate the learning ability of the proposed network by using parameters determined by experiments. Adaptive connections between artificial neurons are implemented using photorefractive (PR) waveguides that can be optically modified by guided beams. The network consists of three layers and has bipolar weights within the limited range. The bipolar weight is encoded as the difference between optical power transmittances of signal beams in two channels of the PR waveguides. The adaptivity of the transmittance of PR waveguide is experimentally evaluated and is incorporated into the proposed network simulated in a computer. The proposed network is trained by a simplified local learning algorithm. Numerical results showed that the proposed three-layered network with six hidden neurons can solve the exclusive-or problem. 相似文献
9.
研究了入射光调制条件下Ce∶KNSBN晶体两波耦合动态过程.结果表明,入射光调制抑制了光扇噪音对Ce∶KNSBN晶体两波耦合动态过程的影响,提高了透射信号光强度.同时研究了入射光光强比Ip/Is及入射光总光强Io对最佳调制频率及增益改善Gm/Gf的影响.结果显示,同一Io下,Ip/Is为100时,Gm/Gf到达峰值1.52,对应的最佳调制频率为150 Hz;同一Ip/Is下,Io为57 mW/cm2时,Gm/Gf最大为1.53,对应的最佳调制频率为175 Hz. 相似文献
10.
We investigate experimentally and numerically a novel method of modifying photorefractive waveguides in a lithium niobate crystal by a guided beam. The guided beam with a strong optical power can change the refractive index of the photorefractive waveguide because of the photorefractive effect. The modification of waveguide structure can be utilized for optical dynamic interconnection. Changes of optical characteristics of a probe beam caused by a modification beam are investigated. Experimental results show that the transmitted power or the peak intensity of the probe beam decreases exponentially as a function of total exposure energy of the modification beam. We also numerically analyze the refractive index change caused by the modification beam in the photorefractive waveguide. The numerical results show good agreement with the experimental results. 相似文献
11.
Takeharu Innami Ryushi Fujimura Masahiro Nomura Tsutomu Shimura Kazuo Kuroda 《Optical Review》2005,12(6):448-450
The photorefractive effect was observed in He-ion-implanted semi-insulating GaN film in the UV spectral region. The photorefractive
grating is induced by the electroabsorption effect near the band-edge. Two beam coupling experiments were performed at a wavelength
of 363.8 nm. The experimental results indicate that absorption grating mainly contributes to the beam coupling. 相似文献
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This paper reports that when an intense extraordinary-polarized laser beam
illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is
formed to be a thermal-like light source with a long correlation time and wide
spectral bandwidth. The experimental results of the first- and second-order
double-slit interference with such photorefractive fanning light source, can be
understood with the theoretical simulation in terms of Hanbury-Brown and Twiss
effect. 相似文献
14.
Takeshi Hashimoto Ikutoshi Fukushima Mitsuru Namiki Kimiaki Yamamoto 《Optical Review》1998,5(3):152-157
We show a prototype of a coding system for image compression using vector quantization with an optical inner product processor, whose accuracy is improved by the applying data transformation method. We also present compression effects for gray-scaled images by this system. The system can compress 256X256X8 bits image data within 1.2 seconds under 0.18 compression ratio with an adequate quality. 相似文献
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Saad Rfifi 《理论物理通讯》2018,69(3):311-316
We let a set of beam splitters of vacuum mode with a chosen transmittance parameter η in interaction with a separable coherent states.This model induces the production of an attenuated quantum channels based on entangled optical states.Indeed,the decoherence effect is exploited positively here to generate such kind of quantum channels.Next,the amplitude damping and the entanglement amount of these produced channels are enhanced thereafter by a probabilistic quasi amplification process using again a 50 : 50 beam splitter. 相似文献
18.
利用受扰光纤理论理论和光纤弹光效应理论对YAP晶体光纤弹光效应进行了理论分析和实验研究。结果表明,这种晶纤可以弹光调制、压力和加速度传感等方面得到应力,并为该类传感器的设计提供理论根据。 相似文献
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光学渡越辐射作为高能强流电子束束流参数测量的一种方式, 具有时间响应快、分辨率高等特点, 可以测量电子束的束剖面、发散角、能量等多个参数;通过电子束束参数的时间分辨测量则能够了解电子束产生、运输中的问题, 非常有利于加速器的研究与调试. 一种具有时间分辨能力的、利用光学渡越辐射进行高能强流电子束参数测量的系统被建立起来, 并应用到了18.5MeV, 2.5kA, 90ns的实际的电子束束参数的在线测量中, 具有以10ns的时间间隔和3ns的曝光时间来获得90ns内相应的时间分辨的束发射度的变化值的能力, 为加速器的研究提供了又一个强有力的测试手段. 该系统具有的时间分辨能力最高到达10ns, 一次可以拍摄到8幅图像, 最小的曝光时间为3ns, 图像分辨率为1376×1035, 幅面可以达到φ80mm以上. 相似文献