Proposal for an Ultracompact Polarization-Beam Splitter Based on a Photonic-Crystal-Assisted Multimode Interference Coupler

An ultracompact polarization-beam splitter (PBS) combining a multimode interference (MMI) coupler and some photonic crystal (PC) structures is presented. The MMI coupler is designed to collect polarized powers reflected by or transmitted through an internal PC structure. The simulation result shows that the designed PBS is very short (about 50 mum), and has a low insertion loss, a high extinction ratio, and a broad bandwidth     

多模干涉耦合器中光传输特性的分析与模拟

本文采用导模传输分析法分析多模波导的传输特性,模拟多模波导横向场分布,得到了多模波导3种干涉单像和多像位置的表达式,为多模干涉耦合器的参数设计提供了有利的手段。     

Temperature Dependence of Characteristics for Multimode Interference Based 3—dB Coupler in SOI

The temperature dependence of characteristics for multimode interference (MMI) based 3-dB coupler in silicon-on-insulator is analyzed, which originates from the relatively high thermo-optic coefficient of silicon.For restricted interference 3-dB MMI coupler,the output power uniformity is ideally 0 at room temperature and becomes 0.32 dB when temperature rises up to 550 K.For symmetric interference 3-dB MMI coupler,the power uniformity keeps ideally 0 due to its intrinsic symmetric interference mechanism.With the temperature rising,the excess loss of the both devices increases.The performance deterioration due to temperature variety is more obvious to restricted interference MMI3-dB coupler,comparing with that of symmetric interference MMI3-dB coupler.     

紧缩型SOI多模干涉光开关的设计

提出了一种新的紧缩型SOI多模干涉(MMI)光开关。开关由单模输入输出波导和MMI耦合器组成。通过在多模波导区域引入调制区,利用Si的等离子色散效应(PDE)改变调制区的折射率来实现开关动作。用FD-BPM方法对开关的工作原理和性能进行了模拟与分析。结果表明,光开关良好的综合性能,而整个开关的长度只有7mm。     

Analysis of Coupling and Radiation Properties for an Improved Dielectric Waveguide Directional Coupler Utilizing a Tapering Left-Handed Slab Core

The coupling and radiation characteristics of an improved dielectric waveguide directional coupler with a tapering left-handed slab core located in the coupling region are analyzed by the staircase approximation method, which combines the building block approach and multi-mode network theory with a rigorous mode-matching procedure. Particular attentions are directed toward the radiation characteristics under different structural parameters of the coupler. Numerical results indicate that the proposed coupler is very promising by shortening the coupling length significantly while keeping the radiation loss at a low level.     

Analysis of a Two-Section Coupler (Correspondence)

The use of single-section quarter wavelength TEM mode directional couplers having excellent wide-band performance is well known. A method for decreasing the coupling variation with frequency by cascading three quarter wavelength couplers has also been described. The purpose of this note is to analyze, for loose coupling, the behavior of a two quarter wave section coupler and compare the results with a coupler consisting of three sections.     

General matrix theory of self-imaging in multimode interference(MMI) couplers

We present a simple and very general matrix method for predicting the properties of integrated optical multimode interference (MMI) couplers with single-mode input and output guides. We derive a set of N×N matrices which (in the paraxial limit) can be used to predict the complex mode amplitudes in the output guides from the complex mode amplitudes in the input guides for any type of MMI coupler, splitter or recombiner. We compare this theory with experiment for an 11×11 nonuniform coupler     

Multimode interference mechanism in V(z) curves obtained by acoustic line-focus beam

The multimode interference mechanism in the acoustic material signatures of V(z) curves, which generally deforms the dip intervals and the shape, is investigated theoretically and experimentally for the acoustic line-focus beam. It is shown, taking a (111)-Si substrate as an example, that V(z) curves associated with multiple leaky waves are represented as a superposition of elemental V(z) curves with different characteristic dip intervals corresponding to the respective velocities of the leaky waves.     

A Semi-Transparent Mirror-Type Directional Coupler for Optical Fiber Applications (Letters)

A directional coupler for optical fiber applications is constructed of two pieces of optical fibers cut obliquely and a thin dielectric film. Coupling coefficient -20 dB to -10 dB depending on the refractive index of the dielectric film, insertion loss 1 dB, and directivity -20 dB are measured. They agree with the analytical results.     

宽频带圆波导TE_(21)模耦合器的设计方法

给出了宽频带圆极化 TE2 1 模耦合器的设计方法 ,该方法适用于实际工程设计 ,2 0 %的频带内耦合损耗<0 .5 d B,VSWR<1.5 ,轴比 <2 d B。     

宽频带圆波导TE21模耦合器的设计方法

给出了宽频带圆极化TE21模耦合器的设计方法,该方法适用于实际工程设计,20%的频带内耦合损耗<0.5dB,VSWR<1.5,轴比<2dB.     

Design of Compact Hybrid Branch Line Coupler (BLC) for GSM Application

Wireless Personal Communications - This paper presents a compact design of a&nbsp;hybrid branch line coupler (BLC) operating at 1.8&nbsp;GHz frequency for the&nbsp;global system for...     

MIMO-OFDM系统载波间干扰的时域消除

由于载波间干扰（ICI）是影响正交频分复用（OFDM）系统性能的重要因素,一般消除ICI时作信道估计都采用辅助导频的方法,需要使用大量的离散导频,为此提出了一种对MIMO信道中ICI消除的时域均衡方法。该方法利用MIMO空时检测后的数据信息迭代回去,当作导频符号估计出时变信道的冲激响应,然后通过时域均衡消除ICI,而无需额外的导频,在改善系统误误码率的同时,提高了频谱的利用率。     

基于指数型MMI一般成像特性的设计方法研究

研究指数型多模干涉(MMI)耦合器的一般成像特性,提出一种新的基于指数型MMI一般成像特性的器件设计方法,设计了1310nm/1550nm复用/解复用器,并利用FD-BPM仿真分析进行验证.     

Measurement of Two-Mode Discontinuities in a Multimode Waveguide by a Resonance Technique

The deliberate use of two or more propagating modes in a multimode waveguide, and a knowledge of associated control elements, has assumed renewed importance, particularly for millimeter wavelength applications. This paper presents a resonance measurement technique for the precise evaluation of the equivalent network for a lossless shunt discontinuity coupling two nondegenerate modes in a multimode waveguide. The discontinuity structure is placed into a cavity closed by adjustable plungers, and the data consists of those plunger positions which render the cavity resonant in the two modes of interest. This multipoint data is then transformed to permit an analysis of the two-port network in the discontinuity plane by conventional techniques. Computations and experimental results obtained at S band illustrative of the procedure are presented for shunt discontinuities coupling the E/sub 01/ and H/sub 01/ modes in circular waveguide. The accuracy achieved is comparable to that obtained in single mode precision measurements.     

超宽带多节定向耦合器设计

介绍了一种简单易行的多节定向耦合器设计方法.采用平行耦合线的分析理论得到了多节定向耦合器的耦合度通用表达式,再通过耦合度带内波纹波动最小条件求解得到耦合器的设计参数.最后给出了一个设计实例,耦合器在工作带宽1～4 GHz内,插损小于0.4 dB,耦合度带内波动小于±0.25 dB,设计数据和实物测试数据具有很好的一致性.     

多功能2×2 GaAs/GaAlAs多模干涉型光开关分析

提出了一种基于深刻蚀脊形光波导带模斑转换器的多功能2×2 GaAs/GaAlAs多模干涉型光开关,并用变量变换级数展开法及三维有限差分束传播法对其进行了模拟分析与优化设计.结果表明,通过控制多模波导中央的两段Schottky电极,器件可实现交叉态、直通态及3dB耦合器功能,并有较大的制作容差、较宽的工作带宽,只须一个多模波导,器件结构紧凑.采用深刻蚀脊形光波导能够满足多模干涉型器件的精确自镜像要求,并使输入/输出光波导在单模工作下有较大的横截面,较低的弯曲损耗及较小的耦合串扰.通道末端引入的模斑转换器可方便地与单模光纤连接耦合.