共查询到17条相似文献,搜索用时 93 毫秒
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提出一种利用光折变二波耦合放大原理实现图像边缘增强的新方法,在用Cr:SBN晶体作记录介质的实时傅里叶变换全息读写装置中,物光中相对分离的高,低空间频率成分分别与参才光波在晶体中发生二次耦合,由于代表图像边缘信息的高频分量强度远低于低频分量,耦合的结果使得相对较弱的高频分量得到增强,从而使再现的全息像边缘凸出,文中详细讨论了晶体光轴取向及参物比对图像边缘增强效果的影响,分析了不同能量转移方向下实现边缘增强的物理机制,实验结果表明,Cr:BSN晶体有可能成为一种用于图像边缘增强的光折变晶体动态滤波器。 相似文献
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提出一种利用光折变二波耦合放大原理实现图像边缘增强的新方法。在用Cr∶SBN晶体作记录介质的实时傅里叶变换全息读写装置中 ,物光中相对分离的高、低空间频率成分分别与参考光波在晶体中发生二波耦合。由于代表图像边缘信息的高频分量强度远低于低频分量 ,耦合的结果使得相对较弱的高频分量得到增强 ,从而使再现的全息像边缘凸出。文中详细讨论了晶体光轴取向及参物比对图像边缘增强效果的影响 ,分析了不同能量转移方向下实现边缘增强的物理机制。实验结果表明 ,Cr∶SBN晶体有可能成为一种用于图像边缘增强的光折变晶体动态滤波器。 相似文献
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本文报道在InP:Fe中皮秒二波耦合的实验研究.文中测量了瞬态二波耦合增益随泵浦光与探测光相对延迟时间改变而变化的曲线,分析了瞬态二波耦合中各种过程的特性,最后还利用皮秒二波耦合实现了低开启光强、高信噪比,透过率达17%的皮秒光开关. 相似文献
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首次报道四方相FeiKTN晶体的二波耦合性质.测得晶体的二波耦合增益系数和衍射效率分别为7.3cm~(-1)和42%,响应时间为2.8sec.文中还分析了主要载流子的符号并计算了其它参数. 相似文献
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热效应对光折变晶体两波耦合的特性影响的理论分析 总被引:2,自引:1,他引:2
用一种模型对两波耦合进行了分析,导出了强度相位的解析式,对影响两波耦合的参数进行了理论分析。分析了对BaTiO3光折变晶体的两波耦合的测量结果。 相似文献
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从实验上研究了不同外加直流电场作用下固液同成分的SBN:Cr和SBN:Rh晶体的光致折射率变化规律.测量结果表明:无外加电场作用时,晶体中的光致折射率变化不明显;若在光辐照晶体的同时,沿晶体c轴方向施加一定方向的外电场,则晶体中即刻出现显著的光致折射率变化.这种折射率变化随外加电场的增大而增大,并且电场方向不同,折射率变化的正负也不同.因而可以通过改变外加电场的极性和幅度控制SBN:Cr和SBN:Rh晶体中光致折射率的变化特性,这对于在该类晶体中制作动态光波导具有重要意义. 相似文献
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Light-induced scattering in SBN:Cr crystal under external electric fields and its suppression 下载免费PDF全文
In this paper, the enhancement of light-induced scattering in congruent SBN:Cr (Sr_{0.61}Ba_{0.39}Nb_2O_6:Cr) crystals in the presence of an externally applied electric field and its suppression are studied. If a coherent image is focalized in SBN:Cr crystal without applying external electric field, the output image will remain clear, because of the weak photorefractive effect in the crystal. When a field is applied properly along the crystal axis, markedly enhanced scattering from the signal beam and the output image dispersion can be observed due to the increase of the photorefractive two-beam coupling gain and the light-induced index change in SBN:Cr crystals. By introducing a coherent or incoherent beam with higher intensity the light-induced scattering can be suppressed through the erasure of scattering gratings. The difference between coherent and incoherent beam is that the former can also amplify the signal beam as the scattered light is removed, whereas the latter can only make the signal beam revert to its initial state. The results obtained under different experimental conditions are consistent with theoretical analysis. 相似文献
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INVESTIGATION OF PHOTOREFRACTIVE TWO-WAVE COUPLING IN Cr-DOPED STRONTIUM BARIUM NIOBATE CRYSTAL 总被引:1,自引:0,他引:1 下载免费PDF全文
We present here the experimental results of photorefractive two-wave coupling in the congruent strontium barium niobate (SBN:61) crystal doped with 1000ppm Cr. Employing a He-Ne laser (632.8nm), we observed the coupling characteristics under different conditions. The crystal shows excellent photorefractive properties, with a high coupling coefficient nearly 6cm-1 as the beam intensity ratio m is less than 100. The saturated coupling coefficient of SBN:61:Cr shows a maximum at a certain external beam crossing angle 2θpeak, which varies with different m, showing a nearly linear dependence on m. The saturated coupling response time τ is measured to be less than 0.8 s. The response time decreased with increasing beam crossing angles no matter how large m is. We also observed the behaviour of the probe beam in reversed experimental procedures. We found that the probe beam shows a bistable state in both procedures. 相似文献
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SBN:Cr晶体中孤子诱导的实时平面光波导及其导光特性分析 总被引:2,自引:1,他引:1
通过数值模拟和实验对SBN:Cr晶体中的(1+1)维亮屏蔽空间孤子及其诱导的实时平面光波导的导光特性进行了研究.采用分步束传播法和Petviashvili迭代法对(1+1)维亮屏蔽空间孤子的特性进行了模拟.通过求解本征方程,对孤子诱导平面波导中存在的导波模式进行了数值求解.采用633 nm的He-Ne激光作为孤子诱导光束,532 nm的半导体泵浦的固体激光作为探测光,在固液同成分的SBN:Cr晶体中进行了实验研究.实验结果和数值模拟的结果符合的很好.而且结果表明SBN:Cr晶体中红光诱导的波导可以作为实时光波导. 相似文献
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The dynamical evolution and stability of
bright dissipative holographic solitons in biased photorefractive materials
in which the self-trapping beam obtains a gain from the pump beam via two-wave
mixing has been investigated numerically. Results show that these solitons are stable relative to small
perturbations. Adjusting some system parameters, such as the bias field and
the angle between beams, can easily control the generation of such solitons.
Potential applications in optical switches or repeaters are discussed. 相似文献
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利用扩展的准直He-Ne激光束通过菲涅耳双棱镜所形成的干涉光场辐照SBN:Cr晶体, 同时沿晶体光轴方向施加适当的直流电场,可在晶体中形成类似于体相位光栅结构的阵列平 面光波导. 采用马赫-曾德干涉仪光路实时测量了所写入阵列平面光波导的横向折射率分布 ,其峰值接近10-4. 初步的导光测试结果表明,利用周期结构光辐照并辅以适当的外加电场在SBN:Cr晶体中写入阵列平面光波导是可行的. 并且由于SBN:Cr晶体的快速响应特性,所写入的光波导是动态的,可随着写入光的撤除而快速消失,或通过改变双光束夹角
关键词:
SBN:Cr晶体
结构光辐照
阵列平面光波导
折射率分布
外电场 相似文献
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CAI Xin LIU JinSong & WANG ShengLie Wuhan National Laboratory for Optoelectronics School of Optoelectronic Science Engineering Huazhong University of Science Technology Wuhan China School of Science Wuhan University of Technology Wuhan 《中国科学:物理学 力学 天文学(英文版)》2010,(5)
The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and experimentally.Both the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams increase.In accordance with these results,the state of two Gauss... 相似文献