共查询到20条相似文献,搜索用时 31 毫秒
1.
A novel graphical representation of the supermode theory of a waveguide directional coupler based on phasor analysis is described. Following this approach, dependence of the magnitudes and phases of the output fields on the splitting ratio of a directional coupler is discussed. Both the cases of phase-matched (identical) and non-phase-matched (non-identical) waveguides constituting a directional coupler are investigated. This approach directly illustrates the fact that the phase shift suffered by the coupled light relative to the throughput light is π/2, regardless of the splitting ratio for identical guides, which is not the case for couplers with non-identical waveguides. It also yields additional information about the phases of the output fields of a directional coupler. The usefulness of this approach in the context of wavelength-flattened couplers, wavelength division multiplexing couplers, and polarization effects in directional couplers is also discussed. This approach should also be helpful in the analysis of guided wave interferometric devices such as wavelength interleave filters and modulators, based on concatenated directional couplers. 相似文献
2.
偏振脱敏高隔离度高分子波导分波器设计 总被引:1,自引:1,他引:0
提出了一种新的高分子波导分波器结构,用以改善波长串扰以及偏振变动、波长带宽等引起的劣化影响.主要技术特征是采用两支参量不同的波导来构成非对称定向耦合器.报告了用非对称定向耦合器构成的马赫-泽德尔干涉型波导分波器的结构特点、基本工作原理和光学特性,详细讨论了器件的设计原理和器件性能优化的处理方法.采用三维波束传播法做了仿真验证,结果表明,该器件在1 550±5 nm和1 310±5 nm的波长带域上、对两个正交偏振态均实现了串扰小于-40 dB的高隔离度分波特性. 相似文献
3.
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
4.
5.
The power-transfer function of asymmetrical directional couplers consisting of two polished single-mode fibres with different core diameters and refractive-index differences has a band-pass behaviour over the wavelength. The fixed centre wavelength of the bandpass is determined by the fibre parameters only. Theoretical calculations show that, by inserting an intermediate dielectric layer with suitable thickness and shape between the fibres, the centre wavelength can be shifted easily over a range of ±30 nm. Experimental results are in good agreement with theory. 相似文献
6.
Photonic crystal waveguide directional couplers as wavelength selective optical filters 总被引:4,自引:0,他引:4
Waveguide directional couplers, formed by two closely spaced linear defect waveguides in a two-dimensional photonic crystal of air holes in a semiconductor matrix, are numerically studied using plane wave expansion and finite difference time domain methods. The coupling lengths are on a wavelength scale and show a strong wavelength dependence, allowing for the design of compact wavelength selective optical filters. Applications as a channel interleaver for the 1.55 μm wavelength range and as a micrometer sized 1.31/1.55 μm wavelength demultiplexer are presented. 相似文献
7.
H. Kurt 《Applied physics. B, Lasers and optics》2009,95(2):341-344
To obtain highly directional light output from photonic crystal waveguides (PCWs), the emission characteristics of the narrow-width
waveguide structures are investigated by tailoring the geometry of the exit sides. The local structural deformations in the
form of air hole removal from the triangular-lattice photonic crystal (PC) show the effectiveness of the previously proposed
approach that was implemented by us for another type of PC. The spatial broadening of the beam is greatly suppressed. With
the modified waveguide exits, highly directional emissions with small side lobes are achieved. The frequency dependency of
the directional emissions is evaluated. We show that the divergence angles of the beams depend linearly on the wavelength
for a regular type of PCW but the modified PCW exits have local minima with respect to wavelength in terms of the divergence
angle. The present work may prove to be helpful in the design of couplers and edge-emitting lasers and in the implementation
of free-space optical communications. 相似文献
8.
应用有效折射率/有限元法(EI-FEM),考虑到LiNbO3晶体和Ti扩散的各向异性,折射率增量与寻常光、非寻常光及波长色散的关系,设计了1.55μm光波长下工作的z切y传播Ti:LiNbO3单模条波导的制备参数,计算和分析了其单模特性、模式场分布及其变化规律.扩展了EI-FEM,将其用于求解耦合波导系统,确定了方向耦合器的耦合长度及其波长色散特性. 相似文献
9.
The even and the odd supermodes of nonlinear directional couplers are determined by means of a variational approach; both slab and channel nonlinear couplers are considered. The validity of the solutions given by the analytical method and their stability properties are analysed through numerical integration of the governing equations. It is shown that channel nonlinear directional couplers improve the stability of the eigenmodes. 相似文献
10.
Chii-Chang Chen Henri Porte Jean-Pierre Goedgebuer Vincent Armbruster Richard Ferriere 《Optics & Laser Technology》2002,34(6):453-455
The coupling ratio of directional couplers in Z-cut Y-propagation and X-cut Z-propagation LiNbO3 crystals was adjusted by laser ablation. The coupling ratio change is more efficient for the TM-mode of Z-cut couplers. The method can be used to correct the uncertainty of the coupling ratio for directional couplers that occurs during fabrication process. 相似文献
11.
ABSTRACTOptical broadband directional couplers (BDCs) are indispensable components for providing wavelength-insensitive and flexible optical splitting in the construction of functional photonic integrated circuits (PICs). The existing BDC device structures are usually required to determine specific design parameters for different waveguide structures and operating wavelength bands. To circumvent this dilemma, here we present a novel optimization procedure to realize a compact BDC by using the asymmetric curved waveguide structure. The versatile particle swarm optimization (PSO) technique is adopted to determine the optimal device parameters of the compact and broadband asymmetric curved directional couplers (ACDCs) for different coupling ratios. In order to reduce the computational complexity in the optimization, the 3D ACDC is first converted to an equivalent 2D structure by using the modified effective index method (MEIM). The device parameters of the equivalent 2D ACDC are optimized by the PSO with the objective function of a wavelength flattened coupling ratio. Afterward, the optimized 2D structure is converted to the 3D one by including the waveguide thickness. To cope with the approximation error by the MEIM, the 3D ACDC is further fine-tuned by sweeping one of the device parameters with the full 3D simulation but keeping all of the other optimal parameters obtained from the PSO intact. As a result, a DC with broad bandwidth of 100 nm is obtained over the wavelength range from 1.50 µm to 1.60 µm with a very small coupling length of 6 µm. The semi-optimized ACDC is used to construct an unbalanced Mach-Zehnder interferometer (MZI) and a Sagnac loop mirror (SLM), both of which show high extinction ratios of >25 dB over a broad wavelength range with low excess loss. 相似文献
12.
Liqun Xu Shijie Lin Lanfen Qi Ye Luo 《International Journal of Infrared and Millimeter Waves》1988,9(3):265-272
A practical design of nonradiative dielectric (NRD) waveguide directional couplers is presented. The dispersion characteristics of coupled NRD-guides and the scattering coefficients of NRD-guide directional couplers are studied as well as the transitions from metal rectangular wave-guide to NRD-guide couplers. Experiments of 3-dB and 10-dB NRD-guide couplers in ka-band show that the couplers are of good performance and promise in millimeter-wave integrated circuits. 相似文献
13.
A new type of wavelength selective filter, based on high differential dispersion between two coupled waveguides, is presented. The Bragg Reflection Waveguide displays high effective refractive index dispersion, due to the interaction of the guided mode with the two confining Bragg reflectors. When coupled with a weakly guided buried channel silica waveguide, a very narrow bandwidth filter (<1 nm) can be easily produced, in a shorter length, with respect to directional couplers made with standard step index channel waveguides. The complete design methodology, fabrication and characterization are presented. 相似文献
14.
15.
Najmeh Nozhat 《Optics Communications》2011,284(13):3449-3455
In this paper, the metal-insulator-metal (MIM) plasmonic directional coupler (PDC) with 45° waveguide bends based on surface plasmon polaritons (SPPs) excitation has been analyzed by the finite-difference time-domain (FDTD) numerical method. Effects of the variations of the coupler length and the metal gap thickness on the output powers and the propagation loss at 1550 nm wavelength have been studied. By choosing proper coupler lengths, power splitters with various output power ratios at 1550 nm wavelength and multi/demultiplexers, as some applications of the directional couplers have been proposed and their performances have been simulated. 相似文献
16.
M. I. Belovolov E. M. Dianov A. V. Kuznetsov A. M. Prokhorov 《Fiber and Integrated Optics》2013,32(4):239-253
A new design of Y-type end-fused single-mode fiber directional couplers has been suggested and its optimum parameters to obtain losses of 0,5–1 dB have been determined. A technique has been developed for fabricating such couplers by electric arc fusion of single-mode fibers with thin claddings. Excess loss in these couplers splitting into two channels is 1—3 dB and the value is in good agreement with calculations. Cross-talk attenuation between reverse channels exceeds 60 dB, which is an indication of high directivity of the couplers. It has been found by experiments that the developed couplers maintain the state of polarization of the propagating radiation. 相似文献
17.
M. I. Belovolov E. M. Dianov A. V. Kuznetsov A. M. Prokhorov 《Fiber and Integrated Optics》1987,6(4):239-253
A new design of Y-type end-fused single-mode fiber directional couplers has been suggested and its optimum parameters to obtain losses of 0,5-1 dB have been determined. A technique has been developed for fabricating such couplers by electric arc fusion of single-mode fibers with thin claddings. Excess loss in these couplers splitting into two channels is 1—3 dB and the value is in good agreement with calculations. Cross-talk attenuation between reverse channels exceeds 60 dB, which is an indication of high directivity of the couplers. It has been found by experiments that the developed couplers maintain the state of polarization of the propagating radiation. 相似文献
18.
We demonstrate a polarization rotator based on adiabatic mode evolution on silicon for polarization-diversified circuits. The rotator has a device length of 420?μm, a polarization-conversion efficiency of more than 90%, and an insertion loss less than 1?dB for a wavelength range of 80?nm. Combining the rotator with a compact, broadband polarization beam splitter based on cascaded directional couplers enhances the polarization conversion extinction ratio to over 30?dB with less than 1.5?dB total insertion loss over a 60?nm spectral range. 相似文献
19.
定向耦合器是构成各类光子器件的基础元件. 本文采用一种基于电场分量的全矢量有限元法, 分析由梯形截面硅基水平多槽纳米线构成的定向耦合器. 给出了准TE与准TM偶、奇模有效折射率、耦合长度及模场分布, 揭示了其模式的混合特性及模场分布特点. 分析结果表明, 准TE模与准TM模的耦合长度随波导间距的增大均呈指数增长, 其中准TE模的耦合长度对波导侧壁倾角的变化敏感, 而准TM模的耦合长度对槽厚及槽折射率的变化敏感. 恰当选择结构与材料参数, 可实现两偏振态下相同耦合长度, 定向耦合器在偏振无关条件下工作. 相似文献
20.
A variational analysis of graded optical directional couplers is presented. Fabrication of such directional couplers by an electron-beam writing method has recently been reported. We have shown that our analysis gives better results than the WKB method which has been used previously to analyse such couplers. Further, our analysis involves much less algebraic and numerical work than the WKB method. 相似文献