共查询到19条相似文献,搜索用时 78 毫秒
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梯形介质膜光栅衍射特性分析 总被引:3,自引:1,他引:2
基于严格耦合波理论建立了梯形介质膜光栅的衍射机理模型,利用该模型讨论了底角为70°的梯形介质膜光栅-1级的衍射行为.通过对梯形介质膜光栅的占空比、槽深和剩余厚度的优化,设计了应用于1053 nm和51.2°角度入射的梯形介质膜光栅.对于顶层为HfO2的介质膜光栅,当槽深为200 nm,剩余厚度为100 nm,占空比为0.35时.其衍射效率优于99.5%,而对于顶层为SiO2的梯形光栅,为获得99.5%的衍射效率.其槽深为800 nm,剩余厚度为320 nm.而且,获得同样的衍射效率,顶层为HfO2的梯形光栅具有更宽的光谱特性.数值计算表明,严格耦合波理论模型对梯形介质膜光栅衍射效率的计算具有很好的收敛性和稳定性. 相似文献
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任意槽形金属光栅矢量模式理论的数值计算 总被引:1,自引:1,他引:0
本文根据任意槽形金属光栅的矢量模式理论,对正弦槽光栅和半椭圆槽光栅的情况进行了推导和数值计算。对任意入射方向和偏振态的入射场,计算了其衍射场的分布情况,并详细研究了光栅结构参数(光栅常数、槽宽、槽深等)对衍射场的影响。 相似文献
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矩形槽光栅矢量模式理论的数值计算 总被引:1,自引:1,他引:0
本文根据矩形槽光栅的矢量模式理论进行了数值计算。对于任意入射方向及任意偏振态的入射场,计算了其衍射效率和偏振特性变化,并详细研究了光栅结构参数(周期、槽宽、槽深等)对衍射场的影响。 相似文献
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在流形元的基础上,提出了非协调数值流形方法,非协调数值流形方法的优点是在不增加广义节点自由度的前提下,大大提高数值流形方法的计算精度和计算效率.利用内部自由度静力凝聚处理,推导了消除内参后的单元应变矩阵和单元刚度矩阵.在Hilbert空间内,从最小势能原理出发对非协调数值流形方法的稳定性和收敛性进行了分析和讨论,得到了保证非协调流形元解唯一存在和收敛的基本条件,完善了非协调数值流形方法的理论基础.数值试验表明,新单元构造过程简单,有较高的精度,从而证明了本方法的可行性.
关键词:
数值流形方法
非协调元
稳定性分析
收敛性分析 相似文献
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利用正交化列处理法和线性变换,给出了一个确定任意齐次线性代数方程组解空间结构的数值计算方法;分析了该方法的收敛性、计算复杂度、数值稳定性和内在并行性,进而探讨了该方法的应用前景。 相似文献
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Hongting Jia Kiyotoshi Yasumoto 《International Journal of Infrared and Millimeter Waves》2004,25(11):1591-1609
A new formula has been proposed for analyzing arbitrary shaped-gratings. The formula is in very simple form, is always suitable for all the gratings of arbitrary profiles, any depth, and any permittivity. The new formula has a character of satisfying rigorously the energy-flux conservation. The effectiveness and its characters have been confirmed by numerical examples. The numerical examples have shown that the new formula is superior to the classical formulas with Fourier series technique in convergence, computing precision, and stability. 相似文献
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Amin Khavasi 《Optics Communications》2011,284(13):3211-3215
The performance of the adaptive spatial resolution technique is improved by making the resolution function of the coordinate transformation as smooth as possible. To this end, the smoothness of the resolution function is probed and a quantitative criterion is proposed to make the jump points; which were conventionally equidistant from each other, regularized. The here-proposed regularization is applied to two different recent formulations and its effects on the overall convergence rate and on the presence of numerical artifacts in analysis of highly conducting gratings are studied. Dielectric and metallic gratings at optical and microwave frequencies are considered and the helpfulness of the proposed technique is discussed. 相似文献
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A new formulation of the differential method in TM polarization, based on correct representation of truncated Fourier series of products of discontinuous functions, is proposed. Although the derived equations are more complicated than in the classical formulation, the convergence rate with respect to the truncation parameter (with the number of diffraction orders taken into account) is much faster for arbitrary grating profiles, approaching the convergence rate in TE polarization. Numerical examples are presented for dielectric and metallic sinusoidal gratings with a 100% modulation ratio. 相似文献
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We show that the strength of long-period gratings recorded in boron-doped fibers by CO2 radiation can be significantly enhanced by a uniform pre-exposure by the same laser. The resultant gratings could be erased by a similar uniform exposure and then recorded again multiple times with no loss of fiber sensitivity. We suggest that such gratings are formed by reversible densification of the fiber core. These densification gratings have higher thermal stability than gratings written with ultraviolet light. 相似文献
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Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses 总被引:9,自引:0,他引:9
We have fabricated long-period fiber gratings by use of a novel technique using focused irradiation of infrared femtosecond laser pulses. We investigate the thermal stability of the fabricated fiber gratings. The values of the loss peak wavelength and the transmittance of the fiber gratings after heat treatment below 500 degrees C are the same as initial values before heat treatment. The fiber gratings that were fabricated by this technique have a high resistance to thermal decay. We propose that this technique will be useful for fabrication of fiber gratings with a superior aging characteristic. 相似文献
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Characterization of thermal (in)stability and temperature-dependence of type-I and type-IIA Bragg gratings written in B-Ge co-doped fiber 总被引:1,自引:0,他引:1
Suchandan Pal 《Optics Communications》2006,262(1):68-76
The temperature-dependence and the thermal stability of UV-exposed type-I and type-IIA fiber Bragg gratings written in boron-germanium co-doped silica fiber were examined, in terms of their refractive-index modulations and the change in the Bragg wavelengths. The decay in the reflectivity of the gratings with time at different temperatures was studied and modelled according to a power-law and a master aging curve approach. The distribution of the activation energy, for these types of gratings, was evaluated to describe their thermal stability and then the comparison of their stabilities has been made. Temperature-induced reversible and irreversible changes in the grating characteristics were observed. The temperature-induced reversible spectral characteristics of type-I and type-IIA gratings were found to be different in nature. All these results were discussed within the framework of the current theoretical approaches for predicting the stability and operational lifetime of these types of gratings. 相似文献
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The C-method is one of the most efficient and versatile method designed for diffraction gratings. The boundary conditions of the grating can be greatly simplified when the coordinate systems coincide with the surfaces of the grating. Reflectance and Transmission Coefficient Matrix (RTCM) with clearly physical concept is a powerful propagation algorithm proposed for steady and fast calculation of multilayer gratings. In this paper, the C-method is extended to treat the multilayer diffraction grating with the identical or nonidentical surface shapes. Numerical examples including diffraction efficiencies of both dielectric and metallic grating are presented. In addition, the excellent convergence for various adjacent-heights and diffracted orders of our propagation algorithm for TE and TM polarizations is also included. 相似文献