共查询到20条相似文献,搜索用时 359 毫秒
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GeSi/Si异质结布拉格反射光栅是硅基光电集成领域一种重要的集成光学器件,分析GeSi/Si异质结的传光特性和布拉格条件,通过求解布拉格光栅方程,得出耦合系数和耦合效率.利用上述原理设计出入射角为66°,波导层的厚度为2 μm,光栅长度为4 252 μm,槽深为0.05 μm,光栅周期为0.456 μm,滤波带宽为0.214 nm,耦合效率为84.1%的1.3 μm Ge0.05Si0.95/Si异质结单模共面布拉格反射光栅,并用数值模拟了入射光渡电场和反射光波电场的分布. 相似文献
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GeSi/Si异质结布拉格反射光栅是硅基光电集成领域一种重要的集成光学器件,分析GeSi/Si异质结的传光特性和布拉格条件,通过求解布拉格光栅方程,得出耦合系数和耦合效率。利用上述原理设计出入射角为66°,波导层的厚度为2μm,光栅长度为4252μm,槽深为0.05μm,光栅周期为0.456μm,滤波带宽为0.214nm,耦合效率为84.1%的1.3μm Ge0.05Si0.95/Si异质结单模共面布拉格反射光栅,并用数值模拟了入射光波电场和反射光波电场的分布。 相似文献
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二值化梯形透过率光栅是一种具有离轴衍射级次的二维光栅,其各衍射点光强信息和位置信息的确定对该新型光栅的实际应用具有重要意义。然而,目前尚无相关解析理论对其进行合理的描述。为了解决上述问题,通过二维傅里叶变换方法获得了该光栅各个衍射级次光强分布的解析表达式,并根据二维光栅的结构特征给出了在透射式和反射式情况下该光栅满足的光栅方程。这为该新型光栅的光线追迹计算打下了理论基础。最后,将解析表达式计算结果与采用X-Lab软件标量衍射模块计算的数值模拟结果进行比较,验证解析理论的正确性。 相似文献
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提出了以单轴晶体材料为包层,光轴平行于光栅主轴(z轴)的新型啁啾光纤光栅模型,应用耦合模理论和传输矩阵方法在理论上分析了该类光纤光栅中的电光效应和弹光效应,理论研究发现在包层施加沿光栅轴向的电场和应变场可以改变布拉格波长和反射谱。得到了3种不同单轴晶体为包层时布拉格波长λB和反射光谱随外加电场和应变场变化的曲线。研究结果表明当轴向外加电场从1×107V/m变化到8×107V/m时λB减小0.12nm,当外加应变场从0变化到0.04时,λB减小0.45nm。 相似文献
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Some integrated optics devices can be made based on the interdigital electro-optic Bragg diffraction grating. The point-matching
method is extended to the analysis of interdigital electro-optic Bragg diffraction gratings. This method provides a simple
and fast analytic expression of the electric field in the structure. The field distributions are used to calculate the optical
and electrical characteristic parameters of the gratings. The effects of finite conductor thickness have been taken into account
in the analysis. It is shown that the simulation results agree well with the measured data. 相似文献
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Exposure of oxide glass to two coherent light beams with different frequencies ω and 2 ω leads to the buildup of spatial index
gratings in the glass. The kinetics of the writing and relaxation of the gratings is investigated. Illumination with one beam
or a background illumination of the sample accelerates the relaxation process; this acceleration is due to the appreciable
photoconductivity of the glass. The diffraction is found to reach a residual self-maintaining level when a grating is illuminated
continuously with a beam at the fundamental frequency. The results are analyzed on the basis of a model that includes the
coherent photogalvanic current, the accumulation of a grating of nonuniform charges under the action of this current, and
the back-effect of the static field, via electrooptic effects, on the propagation of the beams. It is shown that an optical
instability of the photoinduced index gratings exists in the glass.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 3, 166–170 (10 February 1996) 相似文献
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Aharon J. Agranat 《Physica A》1993,200(1-4):608-612
A new approach for implementing artificial neural networks (ANNs), based ona novel concept in volume holographic storage-electroholography (EH)-is described. EH is based on the use of paraelectric photorefractive crystals in which the photorefractive mechanism is created in the paraelectric phase. Thus the quadratic electrooptic effect is used to transform the information carrying space charge fields into birefringence gratings, and therefore the diffraction efficiency is governed by an external electric field. This principle enables the construction of a page oriented architecture in which each neuron is implemented as a local electronic circuit, governing the diffraction efficiency of a small volume hologram representing the axon of the neuron. The EH approach is expected to enable the construction of networks with 105−106 neurons, each with 103−104 synapses. 相似文献
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We report on the X-ray Bragg diffraction analysis of periodic surface gratings on (100) GaAs crystals. We show that the X-ray Bragg diffraction is a very powerful method to investigate ultrafine surface gratings and allow us to determine not only the grating period but, in particular, the width of the grooves and to characterize the quality of the sidewalls, which is not easily possible with optical methods. The X-ray diffraction on surface crystal gratings is analogue to the Fraunhofer diffraction of multiple slits or reflection gratings. 相似文献
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Hiroyuki Okamoto Kohei Noda Moritsugu Sakamoto Tomoyuki Sasaki Yasuhiro Wada Nobuhiro Kawatsuki Hiroshi Ono 《Optical Review》2017,24(4):510-516
We developed a method for the design of multilevel anisotropic diffraction gratings based on a genetic algorithm. The method is used to design the multilevel anisotropic diffraction gratings based on input data that represent the output from the required grating. The validity of the proposed method was evaluated by designing a multilevel anisotropic diffraction grating using the outputs from an orthogonal circular polarization grating. The design results corresponded to the orthogonal circular polarization grating structures that were used to provide outputs to act as the input data for the process. Comparison with existing design methods shows that the proposed method can reduce the number of human processes that are required to design multilevel anisotropic diffraction gratings. Additionally, the method will be able to design complex structures without any requirement for subsequent examination by a human designer. The method can contribute to the development of optical elements by designing multilevel anisotropic diffraction gratings. 相似文献
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台阶光栅衍射的傅里叶分析 总被引:3,自引:1,他引:2
提出了一种台阶光栅模型 ,并应用傅里叶光学方法推导出了反射式衍射光强的表达式。分析计算了衍射光强随台阶数、入射波长、衍射角和轮廓角 (闪耀角 )的变化关系。结果表明 ,台阶光栅能起到闪耀作用 ,台阶对衍射强度分布有影响 ,但不改变衍射光极大值的位置 ,随台阶数的增加 ,能量逐渐向闪耀方向集中。当台阶数等于 8时 ,其衍射效率可接近三角形闪耀光栅的衍射。台阶光栅衍射的傅里叶分析对光栅制作有一定的指导意义 相似文献
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P. Szwaykowski 《Optics & Laser Technology》1985,17(5):255-260
In this paper, a method — based on the diffraction of light — for producing binary diffraction gratings is presented. It is shown that using two master gratings of the Ronchi type and utilizing the results of the double diffraction system it is possible to produce binary gratings with an arbitrary opening ratio. The results have been extended for a two-dimensional case and it is shown that producing binary grid gratings with arbitrary opening ratios in both x and y directions is also possible. 相似文献