微盘腔垂直耦合器特性的拓展分析

利用垂直于微盘腔边界的波导与腔耦合是一种新开发的耦合技术. 采用有限元数值模拟方法对垂直耦合器的腔尺寸适应性、波长适应性和端口扩展性做出详细分析. 结果证实: 垂直耦合器在大尺寸腔中或者多个波段均有效; 并且多个垂直耦合器可以和同一盘腔交换能量, 实现滤波、分束、光路交叉的功能. 垂直耦合器在以微腔为元件的集成光路中的应用将使材料选取和光路排布更为灵活. 关键词： 微纳光学 微腔 回音壁模式 垂直耦合器     

Mach-Zehnder interferometer with a uniform wavelength period

We have realized a first optical filter composed of optical delay lines and couplers that has a periodic response with respect to wavelength, whereas a conventional optical filter is known to have a periodic response to relative optical frequency. This new filter can be constructed by using a phase-generating coupler (PGC) that supplies the optical delay lines with a wavelength-dependent nonlinear phase. The PGC, which is also composed of optical delay lines and couplers, can simultaneously provide a desired phase and an arbitrary amplitude coupling ratio. We applied our transformation method to a conventional Mach-Zehnder interferometer (MZI) as an example of an optical frequency filter and converted it to an optical wavelength filter. We fabricated the designed MZI on a silica-based planar lightwave circuit and successfully realized what is believed to be the first MZI with a uniform wavelength period.     

Fused biconical tapered fiber-optic devices: Application to data buses

The technology of fiber-optic couplers based on fused biconical tapered structures is reviewed, and the linear and star data-bus configurations that can be constructed using these couplers are discussed. A useful network topology for interconnecting star couplers using the hybrid transmission-reflection star coupler is also proposed. This network configuration has the advantage of requiring significantly less optical fiber than networks employing a single transmission or reflection star.     

Hybrid photonics structures with grating and prism couplers based on ZnO waveguides

This paper presents the results of investigations concerning input-output systems of an electromagnetic wave in the visible and near visible spectrum for their application in structures of integrated optics. The input-output structures used in described planar optical waveguides are in a form of prism and grating couplers. The first part of the paper contains numerical analysis of grating couplers aiming at an optimization of their geometrical parameters, strictly — the depth of the grooves in the grating coupler. The second part presents the practical realization, as well as experimental tests of the planar optical waveguide with the hybrid input-output system. As the input system of the electromagnetic wave, a prism coupler was used, and in the case of the output system — a photonic structure with grating coupler was applied. The investigated planar wave guides with the input-output structures were made of a wide energy band gap semiconductor — zinc oxide (ZnO).     

Fused biconical tapered fiber-optic devices: Application to data buses

Abstract

The technology of fiber-optic couplers based on fused biconical tapered structures is reviewed, and the linear and star data-bus configurations that can be constructed using these couplers are discussed. A useful network topology for interconnecting star couplers using the hybrid transmission-reflection star coupler is also proposed. This network configuration has the advantage of requiring significantly less optical fiber than networks employing a single transmission or reflection star.     

BPM Simulation and Comparison of 1 × 2 Directional Waveguide Coupling and Y-Junction Coupling Silicon-on-Insulator Optical Couplers

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.     

新型1×4塑料光纤功率耦合器的研制

提出了一种新型的塑料光纤功率耦合器 ,该耦合器与传统的拉锥型和混合棒塑料光纤耦合器不同。理论分析了它的损耗特性。该耦合器基于塑料光纤本身的热特性 ,分别将塑料光纤进行拉锥和热缩构成耦合器的两端 ,结构简单 ,制作容易 ,实验结果表明其性能也可满足塑料光纤短距离通信网的要求     

Simulations of refractive index variation in a multimode interference coupler: Application to gas sensing

An optical sensor based on multimode interference couplers structures has been studied. We have introduced the optical parameters of materials used in existing optical integrated circuits and a sensitive material characterised in previous studies. The variation of optical properties such as the refractive index of the covering sensitive material leads to a modification of waveguiding conditions in the multimode interference coupler. A gas sensor can be developed by measuring the variation of light intensity at the output of the multimode interference coupler structure under gas exposure. Simulations have been performed in order to optimise the output light intensity variations to increase sensitivity. We have shown that these structures are more sensitive than Mach-Zehnder interferometers, and that the relation between dimensions and sensitivity of the multimode interference coupler is not trivial.     

全光数字光开关和光限幅器

分析了级联单端输入非线性光波导耦合器的输出特性。理论分析表明这类器件具有极好的开关、限幅以及稳定光功率的特性。调整耦合器的耦合长度,可改变开关的阈值功率和限幅器的门限,且随着级联耦合器数目的增加,开关的动态开关区、消光比以及输出功率的起伏下降。数值分析表明,级联耦合器作为全光开关,消光比可小于－９０ｄＢ,动态开关区可小于３×１０－４Ｐｃ;作为光功率稳定器和光学限幅器,其输出光功率起伏可小于１０－７Ｐｃ。     

Directly laser-written integrated photonics devices including diffractive optical elements

Femtosecond laser-written integrated devices involving Fresnel Zone Plates (FZPs) and waveguide arrays are demonstrated as built-in optical couplers. These structures were fabricated in borosilicate glass using a direct laser writing technique. The optical properties of these integrated photonic structures were investigated using CW lasers and high-resolution CCDs. For a single FZP coupled to a single waveguide, the overall coupling efficiency was 9%. A multiplexed optical coupler composed of three FZP layers was demonstrated to couple three waveguides simultaneously in a waveguide array. Structures of this type can be used as platforms for multichannel waveguide coupling elements or as microfluidic sensors that require higher light collecting efficiency.     

Hybrid Optical Comb Filter with Multi-Port Fiber Coupler for DWDM Optical Network

Optical comb filters based on multi-port fused fiber couplers are proposed and numerically analyzed, 3-arm MZI composed by1fiber splitter and7×33×fiber coupler, and 2-stage cascaded FIR type MZI interleave filter.     

Apodized grating coupler using fully-etched nanostructures

A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency.Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer.     

Design and analysis of a gallium lanthanum sulfide based nanoplasmonic coupler yielding 67% efficiency

In this paper, we propose a novel ultra-compact nanoplasmonic coupler using gallium lanthanum sulfide (GLS) which yields an efficiency of 67% at the optical communication wavelength. The analysis has been done numerically using the finite-difference time-domain method. Our proposed coupler can operate at a broad frequency range and easier to fabricate than couplers with multi-section tappers since it is a simple rectangular-shaped coupler with no variation along the whole length.     

棱镜-漏波导耦合器的理论分析

根据多光束干涉原理,理论上分析了棱镜-漏波导耦合器,且与棱镜-波导耦合器作了比较,给出正确使用这两种耦合器的判据.分析结果表明,在强耦合条件下,棱镜-漏波导耦合器可用于薄膜参数测量和光波导输入-输出耦合;对于弱耦合,本文的结果与Tien和Ulrich的理论一致.     

Spectral properties of asymmetrical optical directional couplers with periodic structures

A comparison is made of co- and contradirectional couplers with periodic structures, with a view to their suitability as WDM devices for integrated optical systems. Expressions are obtained for the spectral response within the framework of a coupled-mode theory. It is shown that the competition between direct Bragg, Bragg-exchange and codirectional coupling in the contradirectional coupler leads to shifting and constriction of the stop bands. Calculations are made for a codirectional coupler with a new type of meander structure and for the contradirectional coupler.     

飞秒激光微细加工中光耦合器参数的数值模拟

用有限差分迭代求解光束传输方程,对1×2(Y型)耦合器和2×2(X型)耦合器分路的夹角大小对分路中光束分配比例的影响进行了模拟研究.模拟结果显示：耦合器夹角控制在一定的范围内,对分路中光束能量分配影响不大;2×2耦合器对分路夹角以及波导宽度的变化敏感.为飞秒激光加工光纤无源器件的可行性做了理论上的分析.     

Fiber devices using polarization- maintaining fibers

Fiber devices using polarization-maintaining fibers called PANDA fibers are presented. They are polarization-maintaining couplers and polarization-splitting couplers, optical isolators and optical circulators, and multi/demultiplexers designed for 1.3 μm wavelength. Crosstalk of-32 dB and excess loss of 0.03 dB for the polarization-maintaining coupler, and polarization-splitting ratio of 17 dB and excess loss of 0.5 dB for the polarization-splitting coupler have been fabricated by a fusion-elongation method. A fiber polarizer with the extinction ratio of more than 40 dB has been presented by using the difference of bending loss between the orthogonal modes in the PANDA fibers. Multi/demultiplexer with narrow band-pass of 1.4 nm utilizing combination of PANDA fiber polarization dispersion and the polarization-splitting coupler has been realized. An optical isolator consisting of fiber polarizers and a spherical YIG with a lens function and an optical circulator consisting of polarizing-splitting couplers and spherical YIGs have been achieved.     

High efficiency grating couplers based on shared process with CMOS MOSFETs

Grating couplers are widely investigated as coupling interfaces between silicon-on-insulator waveguides and optical fibers.In this work,a high-efficiency and complementary metal-oxide-semiconductor(CMOS) process compatible grating coupler is proposed.The poly-Si layer used as a gate in the CMOS metal-oxide-semiconductor field effect transistor(MOSFET) is combined with a normal fully etched grating coupler,which greatly enhances its coupling efficiency.With optimal structure parameters,a coupling efficiency can reach as high as ～ 70% at a wavelength of 1550 nm as indicated by simulation.From the angle of fabrication,all masks and etching steps are shared between MOSFETs and grating couplers,thereby making the high performance grating couplers easily integrated with CMOS circuits.Fabrication errors such as alignment shift are also simulated,showing that the device is quite tolerant in fabrication.     

Fiber devices using polarization- maintaining fibers

Fiber devices using polarization-maintaining fibers called PANDA fibers are presented. They are polarization-maintaining couplers and polarization-splitting couplers, optical isolators and optical circulators, and multi/demultiplexers designed for 1.3 μm wavelength. Crosstalk of-32 dB and excess loss of 0.03 dB for the polarization-maintaining coupler, and polarization-splitting ratio of 17 dB and excess loss of 0.5 dB for the polarization-splitting coupler have been fabricated by a fusion-elongation method. A fiber polarizer with the extinction ratio of more than 40 dB has been presented by using the difference of bending loss between the orthogonal modes in the PANDA fibers. Multi/demultiplexer with narrow band-pass of 1.4 nm utilizing combination of PANDA fiber polarization dispersion and the polarization-splitting coupler has been realized. An optical isolator consisting of fiber polarizers and a spherical YIG with a lens function and an optical circulator consisting of polarizing-splitting couplers and spherical YIGs have been achieved.     

分布式抽运连续光纤激光器研究

为了避免高功率光纤激光器中光纤端面出现热效应问题,依据多点级联结构的耦合器,对分布式抽运的光纤激光器进行了研究。首先,介绍了实验室自主研制的级联耦合器。然后,分析了耦合器插入对光纤激光器的影响。最后,选用自制的耦合器搭建了分布式抽运的光纤激光器。实验结果表明:对耦合器插入损耗的研究,能够促进高功率级联耦合器的实现。在光纤激光器结构中,975 nm泵浦功率注入1.1 k W时,1 080nm激光功率输出为770 W,光-光转换效率为77%。在主控振荡功率放大结构中,激光功率输出为635 W,放大级的光-光转换效率为78%。分布式抽运方式可以使泵浦光多点注入,避免了热量的集中,能够获得千瓦级的激光功率输出。