共查询到20条相似文献,搜索用时 718 毫秒
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We describe and example the Beam Propagation Method (BPM) used to model and simulate nonlinear refractive and absorptive effects in materials with applications to optical limiting and switching. Various scenarios including laser-beam trapping and laser-beam division are investigated, in order to demonstrate the power of the BPM. A novel technique is also described for efficiently modelling the external far-field propagation from nonlinear media, including the propagation of non-Gaussian-shaped spatial profiles. The methods are finally combined with the phenomenon of nonlinear absorption to demonstrate enhanced power limiting in the presence of self-refraction. Optimal parameters for high-fluence power-limiting are subsequently discussed. 相似文献
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The spectral response of an arrayed-waveguide grating (AWG) demultiplexer is calculated by simulating the field propagation in the output section of an AWG with a wide-angle beam propagation method (BPM) in a cylindrical coordinate system. As in a practical design of an AWG demultiplexer, each output waveguide consists of two straight sections connected by a bending section. The spectral response obtained by the present algorithm is more accurate than those obtained with two popular approximate methods, namely, the conventional overlapped integral method and the standard BPM for radially straight and infinitely long output waveguides. With the present algorithm, the dependence of the spectral response on the parameters of the output section is analyzed. The channel crosstalk and the 3 dB passband width of the spectral response depend mainly on the length of the first straight section, the end separation and the angular separation of the output waveguides. The bending section results in an asymmetrical spectral response with remarkable sidelobes which can be reduced by increasing the bending radius. 相似文献
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An efficient and accurate three-dimensional (3D) hybrid modeling, which combines a 3D beam propagation method (BPM) and the two-dimensional (2D) Kirchhoff–Huygens diffraction formula, is developed to simulate the field propagation in an arrayed waveguide grating (AWG) demultiplexer. The 2D Kirchhoff–Huygens diffraction formula is used for the simulation of the light propagation in the free propagation regions (FPRs). A 3D BPM in a polar coordinate system is used to simulate the light propagation in the transition region between the input FPR and the arrayed waveguides so that the coupling coefficients for the arrayed waveguides are calculated conveniently and accurately. For the simulation in the transition region between the arrayed waveguides and the output FPR, only the central arrayed waveguide and several adjacent ones are needed in the computational window of a standard BPM and thus the computation efficiency is improved. Finally, a flat-top AWG is designed and fabricated to verify the reliability of the present simulation method. The calculated and measured spectral responses are in a good agreement. 相似文献
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An extension of the beam propagation algorithm based on the method of lines (MoL–BPM) is proposed and substantiated for analysis of curved bends–constituent parts of complicated optical devices, connecting waveguides with different orientation. Cylindrical coordinates are introduced. The formulas are compatible with those in Cartesian coordinates for analysis of straight waveguides. So, in combination concatenations of curved bends and straight waveguides can be examined in a uniform way. For the purpose of analysis in cylindrical coordinates a suitable set of wave equations without any approximation and valid for a general hybrid case is derived. To prove the accuracy of the MoL–BPM in cylindrical coordinates applying the derived formulas, the curvature loss of a rib waveguide was computed and compared with other methods showing very good agreement. As an application of the method two straight waveguides are connected by a curved bend and the power flow is determined. 相似文献
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A new beam propagation method (BPM) is developed based on a direct approximation to the propagator by its [(p-1)/p] Padé approximant. The approximant is simple to construct and has the desired damping effect for the evanescent modes. The method is applied to a tapered waveguide for TM-polarized waves, based on the energy-conserving improvement of the one-way Helmholtz equation. Numerical results are compared with those obtained with other variants of the BPM. 相似文献
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An extension of the recently proposed three-dimensional (3D) wide-angle (WA) beam propagation method (BPM) using complex Jacobi
iteration (CJI) taken into account polarization effects is presented. The resulting iterative BPM is faster than BPMs based
on the traditional direct matrix inversion for waveguides with unchanging refractive index profiles during propagation direction.
However, for varying refractive index waveguides the iterative method suffered from the fact that the iteration count between
two successive cross-sections increases dramatically during the propagation direction. To overcome this problem, we propose
the utility of the iterated Crank–Nicholson method. At each propagation step, the propagation equation is divided in multiple
stages by the iterated Crank–Nicholson method and then each stage is recast in terms of a Helmholtz equation with source term,
which is solved effectively by the complex Jacobi iterative method. The resulting approach is stable and well-suited for large
structures with long propagation paths. 相似文献
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采用三维波束传输法的多模干涉耦合器成像位置的数值计算 总被引:2,自引:1,他引:1
多模干涉(MMI)耦合器需要精确定位成像位置,以便器件的设计制作。针对强限制和弱限制的三维多模波导干涉耦合器,采用三维交替方向隐式有限差分光束传输法(BPM),数值计算得出多模波导长度、输入波导和输出波导位置。首先通过对对称干涉多模干涉耦合器的数值分析求得多模干涉耦合器的等效宽度Weq及最低二阶模之间的拍长Lc,然后将这些参量结合光束传输法直接用于器件设计。计算显示该方法得到的成像位置和导模传输分析法(MPA)的理论预测比较接近,但Weq和Lc却是由光束传输法计算得到的,导模传输分析法理论只能在得到Weq和Lc的前提下才能得到成像位置。该方法直接针对三维波导进行,没有采用基于等效折射率方法的从三维波导到二维波导的简化处理,并且也没有采用导模传输分析法所采用的近似,保证了计算精度,对于实际多模干涉器件的设计制作可起参考作用。 相似文献
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A novel device capable of rapid and accurate wavelength determination in the C-Band of the telecommunications grid is presented. The device was developed with Planar Lightwave Circuit (PLC) technology, making it an ideal candidate for incorporation into next generation reconfigurable networks at add/drop sites that require stringent routing control. The described wavelength-meter can resolve any wavelength to a 2–5 pm precision within a sub-microsecond timeframe. The basic theory is outlined before the numerical aspects of the design and modelling are addressed. By establishing quadrature between two phase-shifted signals provided by two similar Fabry–Perot cavities, the interferometric throughput is referenced to a linear dielectric filter to resolve the wavelength in question. The elaborate mechanisms associated with multiple reflections in concatenated Fabry–Perot etalons warrant a meticulous verification by means of bidirectional beam propagation methods (BPM), discussed infra. Experimental characterisation verifies the theory. This signifies that concept of quadrature can also be applied in disciplines such as optical sensing and biophotonics. Thus, the device can be considered as a Generic Lightwave Integrated Chip (GLIC). 相似文献
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The beam propagation method (BPM) has been widely used in numerical simulations of optical waveguides that vary slowly in the propagation direction. However, when BPM is used over a large propagation distance, a significant amplitude error in the coefficient of the leading propagating mode can be observed. Energy-conserving corrections and the single scatter approximation have been used to improve the accuracy of the BPM. 相似文献
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For developing large area opto-electronic silicon-on-insulator (SOI) devices, the optical coupler is a basic key device. In this article, the authors design and simulate 1 2 2 directional waveguide coupling and Y-branch coupling optical couplers based on Unibond SOI rib waveguides. The beam propagation method (BPM) is used for light propagation analysis. The simulation results and comparisons of the two kinds of optical couplers are reported. The S-bend waveguide for attaching to the two kinds of SOI optical coupler is also analyzed by BPM. We find that the directional coupler has lower power loss, but the Y-junction coupler is more wavelength insensitive with the same device size and splitting angle. The fabrication tolerance analysis shows Y-junction coupler has better fabrication characteristics. 相似文献
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Lars Thylén 《Optical and Quantum Electronics》1983,15(5):433-439
Simple quantitative conditions for the applicability of the beam propagation method (BPM) in isotropic and anisotropic media are given. These conditions are derived using the operator formalism employed in the BPM in its conventional formulation. The basic limitations of the BPM are highlighted at the same time. 相似文献
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We propose a novel beam-propagation method (BPM) based on the higher-order Padé approximants in both the transverse and the longitudinal directions. Extending the Padé approximation to the propagation direction and adopting the multistep method increase the programming effort by only a small amount. Compared with the conventional BPM's, this method is more accurate and efficient. The accuracy and the propagation step size are well predicted by a phase analysis. 相似文献
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Due to the lens-induced quadratic phase factor from converging lens, the beam-propagation method (BPM) is computationally expensive in simulations by the sampling theorem for lens-induced strongly focused beams propagating in nonlinear media. In the paper, we present a modified approach (MA) based on the separate envelope and lens-induced phase to only compute the envelope in the whole focal region. Then we demonstrate the correctness of MA analytically by the propagation of focused Gaussian beam and numerically by that of focused Super-Gaussian beam in linear media. Numerical simulations of strongly focused beams based on MA are in good agreement with those of BPM when propagating in Kerr media. The sampling requirement of MA which is similar with no lens-induced phase beam is lower than that of BPM which increases with the lens-induced chirp parameter and the propagation distance. Thus the computational efficiency can be greatly improved. 相似文献
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Design and fabrication of the star coupler based on SOI material 总被引:1,自引:0,他引:1
A 1×25 star coupler is designed through calculation and beam propagation method (BPM) simulation. Improvement methods are focused on the design of the tapered waveguides in the device, improving the uniformity of the output light power of the star coupler. Utilizing the conventional Si process technology, the device is fabricated based on silicon-on-insulator (SOI) material. The test result shows that the star coupler has a perfect function of power splitting. 相似文献