无磁性光子晶体类T型非互易性双通道滤波器设计

基于无磁性二维光子晶体设计了一种由直线波导及矩形谐振腔构成的类T型非互易性双通道滤波器。矩形谐振腔具有局域多频率电磁波且电磁波传播方向可调的特性，直线波导的结构尺寸决定了其对不同对称性电磁波的承载能力。利用矩形谐振腔和直线波导的特性实现了非互易性双通道滤波功能。实验结果表明：正向传输情况下，滤波器实现了中心波长分别为1534 nm和1574 nm，带宽分别为16 nm和8 nm的滤波传输，对应的插入损耗分别为0.4 dB和0.36 dB，通道间隔离度为33 dB和22 dB；反向输入情况下，电磁波对称模式的不匹配导致无法传输。这表明设计的双通道非互易滤波器滤波效果良好，在未来全光通信集成领域具有潜在的应用价值。     

基于表面等离子波耦合的流体波导光栅耦合器

提出了一种由金属光栅和流体光波导结构组成的,基于表面等离子波耦合的光栅耦合器。利用光栅的衍射效应,将金属光栅与介质分界面之间产生的表面等离子波耦合到流体光波导中,并且能够沿着流体光波导稳定地向前传播。通过采用基于有限时域差分算法的FDTD Solutions软件对光栅耦合器进行了参数优化及特性分析,通过优化使该结构在650 nm波长下的耦合效率达到56%。此外,由于该结构对TE偏振光和TM偏振光的选择比达到70∶1,因此具有偏振器的功能。同时由于TE偏振光耦合频谱的频带宽度仅为20 nm,该结构还具有窄带滤波的作用。此外,还研究了光栅结构参数、入射角以及流体折射率对耦合频谱的影响。     

金属膜衬底上亚波长介质光栅结构的特性及传感应用

提出亚波长介质光栅-金属膜-石英玻璃衬底结构,根据等效介质理论该结构可等效为由金属-光栅-包覆层构成的单面金属包覆波导,在入射波长和入射角满足一定条件时,发生导模共振(GMR)从而产生光波全吸收现象。根据严格耦合波分析(RCWA)理论进行数值分析发现,等效波导中的TM1 GMR峰尖锐,并且对光栅包覆层的折射率变化非常敏感,角度灵敏度为127.87°/RIU(RIU为折射率单位),波长灵敏度为409.35 nm/RIU,在很大的折射率范围内线性度良好。与全介质GMR传感器和光栅型表面等离子体共振(SPR)传感器相比,该结构通过GMR实现较高灵敏度的同时,其较窄的共振峰使得检测精度更高。     

基于SOA和F-P环形滤波器的双波长激光器

提出了基于半导体光放大器(SOA)和掺铒法布里-波罗(F-P)环形滤波器的双波长激光器结构。该激光器以半导体光放大器为增益介质,利用其自发辐射起振,激光器中的多模光纤布喇格光栅、法布里-波罗环形滤波器和线型谐振腔都有选频作用。其中,光栅的布喇格波长决定了振荡波长,使激光器产生两个波长的激光输出,线型谐振腔自身的梳状滤波作用和F-P环形滤波器抑制激光器的多余纵模,使得输出激光具有窄线宽特性,得到了线宽为0.05nm双波长振荡。     

磁光光纤光栅法布里-珀罗腔的光谱可调性研究

利用传输矩阵法分析了磁光效应和光栅折射率初始相位对磁光光纤布拉格光栅(MFBG)-法布里-珀罗(FP)光谱特性的影响。通过调节外加磁场的大小及方向,能实现MFBG-FP的可调滤波特性,并能控制甚至抵消光栅折射率初始相位差引起的透射峰平移。对于高光栅反射率的MFBG-FP,透射峰位置和波长间隔可由其有效腔长以及等效磁光耦合系数来解析表达。MFBG-FP的磁可调能力会随着FP腔与MFBG的磁光耦合系数比的增加而增强,磁光耦合系数比大于1的MFBG-FP结构的磁可调特性优于相应的MFBG结构。     

基于双面金属波导的纳米磁流体磁调制

设计了一种双面金属包覆波导,其中作为样品室的导波层厚度达到毫米量级.在波导腔体中注入浓度为0.15%的水基四氧化三铁纳米磁流体,采用波长为860 nm的红外激光束小角度(小于5°)入射到该波导金属耦合层上,以激发波导中的超高阶导模,使纳米磁流体处于光波导的振荡场中.根据超高阶导模的高灵敏特性,对磁流体施加10 mT的调制磁场,检测到纳米磁流体的磁光信号上升和下降时间为2 ms.     

长周期光纤光栅波导色散因子和有效折射率热光系数的测量

对串联的长周期光纤光栅(CLPFG)的透射谱特性进行了理论分析和实验研究。分析表明,长周期光纤光栅中纤芯模和包层模之间的马赫曾德尔干涉效应导致在长周期光纤光栅谐振峰内的梳状滤波结构特性;其峰值位置和峰间距同串联区光纤的长度以及光纤的波导色散因子有关。测量了长周期光纤光栅的透射谱,并研究了其温度特性。根据测量数据,得到对应于1554 nm波长处,所用单模光纤HE14模的波导色散因子γ为0.874;纤芯/包层有效折射率差的热光系数为4.8×10-5℃-1。并对这一测试方法和结果,以及长周期光纤光栅的应用进行了讨论。     

LNOI阵列波导光栅的设计与制备

基于薄膜铌酸锂(Lithium Niobate on insulator,LNOI)材料平台,设计并制备了中心波长1 550 nm、4通道且通道间隔为400 GHz的阵列波导光栅,并完成了 LNOI波导端面抛光.测试结果表明,该阵列波导光栅相邻通道间串扰约-7.5 dB,通道非均匀性小于0.5 dB,中心波长1 551...     

法拉第手征圆波导中旋磁性和手征性的复合效应

基于分离变量和Mller求根法,本文详细地分析了均匀和非均匀法拉第手征圆波导中混合模的传输特性;揭示了模分裂、对称和非互易性、后向波和衰减随不同本构参数的变化規律,而这不同于一般旋磁和互易手征波导情形。     

氧化锌单晶DFB半导体激光器的设计与分析

基于严格耦合波理论(RCWA)和介质平板波导理论,针对光通信中的1550 nm波长,设计了一种基于氧化锌(ZnO)单晶的分布反馈式(DFB)半导体激光器的光栅结构,分析了二维电场模式图以及激射波长线宽图,得到了光栅结构的变化对其单纵模传输的影响。仿真结果表明,当光栅的周期为489 nm,占空比为50%,光栅深度为400 nm时,全局电场能量达到了8.3×107 J,光谱线宽小于0.1 。该激光器具有很好的窄线宽输出以及波长选择特性。理论分析与仿真结果基本一致为后期进行该器件的制备提供了较好的参考。     

在二氧化硅衬底上制备磁光Ce：YIG薄膜用于磁光波导型器件

对Ce1YIG磁光薄膜的制备过程及磁光性能进行了详细的研究．用RF磁控溅射法在二氧化硅的基片．上淀积Ce1YIG薄膜,再对此薄膜进行晶化处理,以得到具有磁光性能的Ce1YIG薄膜．本文讨论了晶化过程中,Ce1YIG薄膜微观结构的变化对其磁光性能的影响．结果表明：采用波长为630nm的可见光测量,薄膜的饱和法拉第旋转系数θF为0．8deg／μm．同时,晶化薄膜易磁化方向为平行于膜面方向,其居里温度点为220℃．所得Ge1YIG薄膜的参数表明：所制备的薄膜适宜于制备波导型磁光隔离器．     

Analysis of an MMI-Based Six-Port Circulator by Using 3-D Magneto-Optical Beam Propagation Method

An MMI-based six-port circulator is analyzed by 3-D magneto-optical (MO) beam propagation method (BPM). Since opposite nonreciprocal 4pi/3-phase shifts are introduced into the two sided interferometric arms of 3 times 3 mirror-image MMI coupler, light travels through this device in a nonreciprocal fashion and obeys the sequential order. After using the Ce:YIG/SOI bonding waveguide to construct the proposed circulator, the 3-D MO BPM formula are validated for the first time to simulate nonreciprocal device with external magnetization perpendicular to the light propagation direction. Simulation shows that this device features in easy fabrication, good operation bandwidth, ability to reduce the port count number.     

Analysis and design of semileaky-type thin-film optical waveguide isolator

This paper describes an optical waveguide isolator that utilizes the unidirectional guided-radiation mode coupling in a magnetooptic/anisotropic slab guide. The basic structure is the semileaky-type waveguide that has been previously used as a polarization mode filter. Specific features of the proposed device are its compact one-section form resulting from the inherent polarization-discrimination property and the relaxed dimensional tolerance due to the automatic phase-matching of coupled modes. Design data and a related discussion are given for the example of LiNbO3/YIG/GGG layered structure operating in the 1.15-μm-wavelength region.     

Beam-propagation in magnetooptic waveguides

The propagation of modes in magnetooptic waveguides distinguishes between the forward and the backward direction. This effect is applied to the realization of integrated optical isolators and circulators. The paper presents a finite-difference beam propagation simulation of such devices. Two different directions of the waveguide magnetization are considered. Finally, some consequences with respect to the practical realization of nonreciprocal integrated optical components are discussed     

A finite element beam propagation method for strongly guiding andlongitudinally varying optical waveguides

A unified finite element beam propagation method is described for both TE and TM waves propagating in strongly guiding and longitudinally varying optical waveguides with magnetooptic materials. In order to avoid nonphysical reflections from the computational window edges, the transparent boundary condition is introduced for both polarizations. In order to show the validity and usefulness of this approach, numerical examples are presented for a directional coupler composed of two parallel identical waveguides, an S-bend, a Y-branching optical isolator, and a 4-ports optical circulator. The present algorithm is, to our knowledge, the first beam propagation method for modeling nonreciprocal magnetooptic components     

An efficient finite-element analysis of magnetooptic channelwaveguides

A finite-element method based on the scalar-wave approximation is developed for the analysis of magnetooptic waveguides. A simple and efficient iterative method is proposed for solving a nonlinear eigenvalue equation derived from the scalar finite-element approach. To show the validity and usefulness of this method, examples are computed for magnetooptic rib-type and ridge-type waveguides. The waveguide structures which have larger nonreciprocal phase shift are discussed     

Optical Faraday rotator using Ce-substituted fibrous YIG singlecrystal grown by floating-zone method with YAG laser heating

A new optical Faraday rotator using a fibrous Ce-substituted yttrium-iron-garnet (Ce:YIG) single crystal was developed. The fibrous Ce:YIG single crystal was successfully grown by the floating-zone method with infrared-assisted YAG laser heating at a fast growth rate. This crystal has a good quality and shows a better figure-of-merit for an optical Faraday rotator at wavelength λ=1.55 μm compared with commonly used Bi-substituted YIG films. Ce:YIG single crystals grown by our method are expected to reduce the cost of optical isolators     

Fabrication and characterization of annealed proton exchanged long period waveguide grating in x-cut LiNbO3

In this paper, a long-period waveguide grating was fabricated in x-cut lithium niobate substrate by patterned annealed proton exchange waveguide fabrication process. The waveguide mode characteristic was evaluated using a charge-coupled device (CCD) camera. It shows that the waveguide is single mode transmission at a wavelength of 1 550 nm. The transmission spectra of the long period waveguide gratings were measured by optical spectrum analyzer (OSA) and show an extinction ratio of ~17 dB and a 3 dB bandwidth of ~10 nm at the resonant wavelength. The resonant wavelength moves toward to the long wavelength direction as the waveguide width-difference increases in the same period, and also shifts toward to the long wavelength direction with the increase of the period in the case of the same waveguide width-difference. The method of fabricating a long period waveguide grating based on a patterned annealed proton exchange technique simplifies the fabrication process, and at the same time, reduces the fabrication cost.     

Nonreciprocal Propagation Characteristics of YIG Thin Film

The characteristics of an optical nonreciprocal phase shifter, with which optical circulators can be constructed, are investigated. We have measured the nonreciprocal phase shift of an appropriately magnetized yttrium iron garnet (YIG) thin film and thus confirmed experimentally that an AIR/YIG/GGG structure can function as an optical nonreciprocal phase shifter.