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A coupled-mode formulation based on complex local modes is developed for tapered and longitudinally varying optical waveguides. Different from the conventional coupled-mode theory that requires integration over the entire spectrum of radiation modes, the new formulation treats the radiation fields via discrete complex modes similarly to the guided modes. Accuracy, convergence, and scope of validity for the solutions of the complex coupled-mode equations are investigated in detail for a typical single-mode waveguide taper. It is demonstrated that the complex coupled-mode theory has overcome the difficulties of the conventional theory in simulation of radiation field effects while preserving the simplicity and intuitiveness of this popular method. 相似文献
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光波导横向耦合模理论包含正交耦合模理论和非正交耦合模理论两大类, 为了追求形式上的完美, 两类理论没有统一的解析解, 并且都没有对非匹配耦合系统中耦合功率的非对称性进行深入研究. 本文一方面由Helmholtz方程出发推导出了一种新型的非正交耦合模方程, 并对两类理论中的耦合模方程进行了统一处理和求解, 得到了一种统一的解析解; 另一方面根据所得到的统一的解析解对非匹配耦合系统中耦合功率的非对称性进行了详细研究, 计算结果表明非匹配耦合系统中的最大互耦合功率和最小自耦合功率均可用统一的解析解进行近似计算.
关键词:
光波导
耦合模理论
耦合器
最大耦合功率 相似文献
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Gómez-Alcalá R Fraile-Peláez FJ Chamorro-Posada P Díaz-Otero FJ 《Optics letters》2012,37(11):2097-2099
In this Letter we employ the general coupled-mode equations of the nonlinear directional coupler and demonstrate that the switching characteristics of prototypical nonlinear racetrack-resonator structures may differ considerably from those obtained when the standard, generally incorrect, coupled-mode equations are used. 相似文献
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Based on the weakly coupled-mode theory, the coupled-mode equations of the spatial multiwaveguide system are presented in general. The intensity distribution in each waveguide is determined by numerical method. Optical logic devices based on spatial multiwaveguide system are proposed. The analysis results show that the spatial multiwaveguide system permits different Boolean logic states obtained by phase modulation.. Applications of the logic devices include optical calculation, optical interconnection, and spatial optical signal processing. 相似文献
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1 Introduction Grating assisteddirectionalcouplerisanattractiveadd dropfilterfordensewavelength divisionmultiplexing (DWDM ) .Anumberofsuchadd dropfiltershavebeenproposedanddemonstrated[1~ 5] .Twomainapproacheshavebeen proposedtosimulate gratingeffectindirect… 相似文献
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A new coupled-mode formulation is developed for grating-assisted parallel optical fiber cores. The theory is derived from the scalar wave equation by perturbation method. The diffraction caused by grating and coupler in the grating region are both considered. Based on the theory, various experimental phenomena in grating-assisted parallel optical fiber cores can be simulated accurately. 相似文献
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基于耦合模理论,得出了三角结构三芯光子晶体光纤(TTC-PCF)的耦合模方程.数值模拟研究了该结构中纤芯间的定向耦合特性,分析了光纤结构及入射波长对耦合系数的影响以及入射光振幅比对纤芯间能量耦合特性的影响.结果表明,通过调节入射光振幅比可实现对纤芯间耦合强度的连续调节.对比了耦合模理论与束传播法得到的结果,两者表现出很好的一致性.结合TTC-PCF展现的独特耦合传输性能,讨论了其在耦合强度连续可调光纤定向耦合器和大模场光纤激光器的设计与制备等方面的可能应用前景. 相似文献
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Using conventional coupled-mode theory, a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings. A helical-core fiber is analyzed as an example. The analysis is simple in mathematical form and intuitive in physical concept. Based on the analysis, the polarization independence of mode coupling in special fiber gratings is revealed. The transmission characteristics of helical-core fibers are also simulated and discussed. 相似文献
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We present here a simple unified derivation of the exact Fokker-Planck equation obtained earlier by Zwanzig and the exact Langevin and transport equations derived by Mori. The derivation, based on the use of a Hilbert space formulation of the dynamics, leads to substantial generalizations of these results in a straightforward manner. We obtain nonlinear Langevin equations for classical systems and discuss the extension of the theory to driven transport and to quantum dynamics based either on the use of density matrices or Γ-space densities as suggested by Wigner. Remaining limitations of the theory are pointed out. 相似文献
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Exact closed-form frequency equations for thick circular plates using a third-order shear deformation theory 总被引:4,自引:0,他引:4
Sh. Hosseini-Hashemi H. Rokni Damavandi Taher M. Fadaie 《Journal of sound and vibration》2010,329(16):3382-3396
This paper presents, for the first time, exact closed-form frequency equations and transverse displacement for thick circular plates with free, soft simply supported, hard simply supported and clamped boundary conditions based on Reddy's third-order shear deformation theory. Hamiltonian and minimum potential energy principles are used to extract the equations of dynamic equilibrium and natural boundary conditions of the plate. The new formulation is verified by comparing the results with their counterparts reported in open literature. Natural frequencies of circular plates with different boundary conditions are tabulated in dimensionless form for various values of thickness-radius ratios. The results presented on the basis of exact, closed-form frequency equations are expected to serve as reliable benchmarks. 相似文献
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A new and simple mathematical formulation that is employed to analyze numerically coupled-mode equations modeling uniform
and non-uniform gratings in optical fiber is investigated. This method would be straightforward and thus beneficial to solve
multimode coupled equations in comparison with a previously used fundamental matrix method, and the Runge--Kutta algorithm.
The new formulation proposed in this study is applied to calculate transmission and reflection spectra of core mode and higher-order
cladding modes of acoustically induced superstructure modulation caused by microbending through fiber Bragg gratings (FBGs).
Co-directional and contra-directional couplings based on acoustically induced modulation in FBGs have been discussed for a
variety of induced coupling coefficients. 相似文献
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V. F. Dmitriev 《Technical Physics》2003,48(2):231-238
Modified coupled-mode equations are employed to develop a theory of filters that use waveguide modes of two surface acoustic
wave (SAW) resonators weakly coupled in the transverse direction. Results of simulation based on this theory are compared
with the earlier experiment. 相似文献
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不在同一平面的空间多波导中光耦合发生在横截面两个方向,利用空间多波导可以方便、有效地实现不同层间器件的互连。将平面波导耦合模理论推广到空间多波导之间的耦合,在弱导引条件下给出了空间多波导的耦合方程。利用该耦合方程对三维集成光学器件中常见的空间三波导和空间四波导的耦合特性进行分析,得出光强分布及耦合长度的解析表达式,并用三维全矢量光束传输法验证了分析结果。分析结果表明利用空间多波导可以实现水平和垂直两个方向上的均匀或非均匀分束,为利用空间多波导之间相互耦合的三维定向耦合器件的设计和分析提供理论基础。 相似文献
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We study the dynamics of vectorial coupled-mode solitons in one-dimensional photonic crystals with quadratic and cubic nonlinearities. Starting from Maxwell's equations, the vectorial coupled-mode equations for the envelopes of two fundamental-frequency optical mode and one low-frequency mode components due to optical rectification are derived by means of the method of multiple scales. A set of coupled soliton solutions of the vectorial coupled-mode equations is provided. The results show that a modulation of the fundamental-frequency optical modes occurs due to the optical rectification field resulting from the quadratic nonlinearity. The optical rectification field disappears when the frequency of the fundamental-frequency optical fields approaches the edge of the photonic bands. 相似文献
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本文利用模式耦合理论,分析了光纤失配耦合器在耦合区带有一个布喇格光栅后两光纤中基模场的传输特性,得到基模场发生耦合现象的条件及满足的方程。采用数值分析方法模拟耦合现象,并得出了带有布喇格光栅的光纤耦合器用于波分复用/解复用的最优化设计方案。 相似文献
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各向同性光波导受到各向同性微扰时的严格矢量耦合模理论 总被引:2,自引:0,他引:2
从Maxwell方程出发,推导出各向同性光波导受到各向同性微扰时严格的非正交矢量耦合模理论,在耦合系数的表达式中发现不包含Wei-Ping Huang 的准矢量耦合模理论中的偏振耦合项,但在推导过程中曾出现过偏振耦合项.最后认为这是由于偏振耦合项是二阶小量,而弱导近似忽略了与之相等的二阶小量耦合项.因此,严格的矢量耦合模理论不存在该项而准矢量耦合模理论可把偏振耦合项作为修正项. 相似文献
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以经典耦合模理论为基础,结合线性啁啾莫尔光纤光栅的结构特性,给出了线性啁啾莫尔光纤光栅的耦合系数和耦合模方程,并用龙格库塔迭代法数值求解耦合模方程.对多种线性啁啾莫尔光纤光栅的光谱特性和时延特性进行了理论模拟.分析结果表明,线性啁啾莫尔光纤光栅的相移特性和切趾特性,使得该类型光栅在波分复用全光网中有着很好的应用前景. 相似文献
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通过利用标准简正波程序KRAKEN计算本地简正波解及耦合矩阵, 进一步发展了求解水平变化波导中声场的全局矩阵耦合简正波方法(Luo et al., "A numerically stable coupled-mode formulation for acoustic propagation in range-dependent waveguides," Sci. China-Phys. Mech. Astron. 55, 572 (2012)), 使得该方法可以处理具有可穿透海底及随深度变化声速剖面等实际问题, 并提供声场的完全双向解. 本文还给出了双层波导中耦合矩阵的解析表达式, 并利用其验证了本方法中耦合矩阵数值算法的精度. 最后, 利用改善后的全局矩阵耦合简正波模型(DGMCM)计算了美国声学学会(ASA)提出的可穿透楔形波导标准问题, 将所得数值解与参考解比较, 结果表明DGMCM方法可以精确处理水平变化波导中声传播实际问题.
关键词:
耦合简正波理论
全局矩阵方法
可穿透楔形波导 相似文献