光脉冲在微环耦合谐振光波导中传输线性特性的数值仿真

利用传输矩阵法得到了微环耦合谐振光波导色散关系的一般表达式,并由色散关系出发讨论了光脉冲在微环耦合谐振光波导中传输时的线性特性,包括带宽、群速度、色散和线性相位变化,这些特性对微环耦合谐振光波导在光通信和光传感领域的应用有重要意义. 关键词： 微环光波导 光脉冲线性特性 传输矩阵法 数值仿真     

微环耦合谐振光波导中的色散控制模型与数值仿真

本文利用传输矩阵法得到了微环耦合谐振光波导的色散关系,讨论了耦合损耗、传输损耗及耦合系数对微环耦合谐振光波导色散的影响,改变耦合损耗、传输损耗及耦合系数可控制其色散曲线的形状、位置、以及带宽,色散曲线的变化及控制对微环耦合谐振光波导在滤波、光信号延迟及缓存等方面的应用有重要意义. 关键词： 光波导 微环光波导 传输矩阵法     

槽型相移布拉格光栅微环谐振器及其传感特性

为实现高灵敏度及高品质因数的折射率传感特性,设计了一种基于槽型相移布拉格光栅的微环谐振器结构。该结构由槽型直波导内嵌相移布拉格光栅耦合单实波导微环构成。结构中离散态光模式与连续态光模式相互干涉产生了Fano共振。利用传输矩阵法量化谐振器中各部分的光场分布,分析系统的传输原理。采用时域有限差分法对提出的器件结构进行仿真模拟,并对结构物理参数进行优化。模拟结果表明该结构的品质因数达到25 729,比传统微环谐振器提高了3倍以上,消光比为18.65 dB,高出传统微环谐振器6.46 dB,折射率灵敏度达到122 nm/RIU,且该谐振器结构简单。所提出的结构在传感应用中具有一定的优势。     

基于方形谐振器的表面等离子体波导传感器

本文利用方形谐振器与两个金属/介质/金属型波导结构耦合设计了一个亚波长的表面等离子体波导传感器,并通过有限元分析研究了此结构的传输特性。研究表明,通过谐振器耦合能有效增强共振波长的表面等离子体波的透射能力,同时减小两侧波导结构与方形谐振器之间的金属势垒层宽度可提高透射率。传感器的共振波长与介质材料的折射率之间存在着线性关系,1阶共振模的灵敏度可达1100nm/RIU。这种传感器可实现器件的小型化,在生物、工业传感领域有着很大的潜力。     

一种包含非线性光学效应的硅基微环稳态模型

微环谐振器是集成光学中的关键器件,它的实际滤波特性会受到输入光功率的影响,但长期以来,微环谐振器的稳态模型仅包含线性光学作用。考虑微环谐振器反馈波导中的光学非线性引入的损耗和相移,以及微环耦合器中光学非线性引入的耦合比改变等因素,推导了考虑自相位调制、双光子吸收和热光效应的微环谐振器的非线性模型。重点讨论了双光子吸收和光学非线性引入的耦合器耦合比改变对微环谐振器陷波深度的影响,仿真结果表明,在热光效应和自相位调制产生谐振谱线频移的同时,功率相关的耦合器耦合比的改变对微环谐振器陷波深度的影响较大。     

加入增益介质的表面等离子体激元耦合共振波导传输特性理论研究

将增益介质加入金属环构成的表面等离子体激元耦合共振波导,利用传输矩阵及时域有限差分方法研究了不同增益系数下该耦合共振波导的透射谱线、色散关系以及群折射率.结果表明,增益介质共振频率附近的反常色散及正常色散变化能有效影响由共振波导几何结构决定的色散关系曲线,且具有相反的效果,分别使其变得平坦和陡峭,从而放大和缩小由共振波导几何结构决定的群折射率.另外,增益系数随外加抽运光改变的特点使得加入增益介质的耦合共振波导具有传输性能可灵活调节特性.文章的研究对促进耦合共振波导在高密度光学集成中的广泛应用具有积极意义. 关键词： 增益介质 耦合共振波导 表面等离子体激元 群折射率     

光子晶体波导慢光特性研究

基于二维三角晶格空气孔光子晶体,通过在光子晶体单线缺陷波导两侧引入不同的耦合腔,设计了慢光特性较好的波导结构.利用平面波展开法计算波导的色散曲线,并分析慢光模式的群速度和群速度色散特性.耦合腔采用单缺陷腔时,适当调节波导宽度可以获得在零色散点群速度为0.0128c的慢光模式,对应在1.55 μm波长处的带宽为409 G...     

曲折圆形槽波导慢波系统的高频特性

 对曲折圆形槽波导新型慢波系统的高频特性进行了研究，通过理论分析和数值计算，得到了它的色散曲线和耦合阻抗表达式，并分析了结构参数变化对色散特性和耦合阻抗的影响。研究表明：当周期变小时色散减弱，耦合阻抗增加；而增大直波导长度时色散变弱，但同时耦合阻抗也会下降。因此较小的周期有利于改善曲折圆形槽波导慢波电路的高频特性。鉴于这种电路的耦合阻抗较低，可以适当地减小直波导长度来提高耦合阻抗。曲折槽波导结合了曲折波导散热能力强、色散特性好、容易加工和槽波导单模工作、低损耗、大尺寸等优点，在毫米波及亚毫米波段的行波管中具有较好的发展前景。     

基于包层模谐振的三包层石英特种光纤温度传感特性研究

提出了一种基于包层模谐振的光纤温度传感器. 它是通过将三包层石英特种光纤(TCQSF)两端分别与普通单模光纤(SMF)电弧熔接构成的SMF-TCQSF-SMF结构. 根据耦合模理论, 首先将TCQSF等效为三个同轴波导, 按各波导模场的分布特点标量计算其传输模式的色散曲线, 并深入研究其耦合长度与传输谱线之间的关系; 其次根据光纤的热光效应及热膨胀效应, 分析计算该传感器的温度灵敏度; 最后选取耦合长度为一个拍长时的传感器进行温度传感实验. 实验结果表明, 在35-95 ℃的温度变化范围内, 其温度灵敏度为73.74 pm/℃, 与理论计算结果一致. 因此, 该传感器具有结构简单、制备容易、灵敏度高、包层模激发可控等优点, 可用于工业生产、生物医学等温度传感领域.     

用于纳米粒子检测的双环谐振器

设计了一种可以探测单个纳米粒子的光学传感器结构,该结构由双环、双环间耦合区的通孔和直波导构成,并引入了Fano效应,进一步增强了粒子在光场中出现时的光耦合场变化.当纳米粒子穿过两个微环间的通孔时,其耦合系数和输出端的光强均发生变化,提出了一种基于双环谐振器结构的高精度耦合系数传感方法,通过检测双环谐振器耦合系数和输出端光强的变化对单体纳米粒子进行精确检测和计数.理论计算结果表明,在损耗为1 dB/cm的情况下,与单环结构相比,双环结构的灵敏度提升了两个数量级.该双环结构在减小波导损耗的同时有效提升了检测灵敏度.     

平面环形谐振腔微光学陀螺结构设计与优化

提出具有高群有效折射率的双环级联作为核心元件的谐振式平面光波导陀螺结构, 基于光学Sagnac原理得到了双微环耦合谐振式光学陀螺理论灵敏度与群有效折射率的一般表达式和双环与单环陀螺系统的灵敏度关系, 并由耦合模理论方法得到了双环系统耦合器的两个透射系数对应的群有效折射率变化情况. 在环腔半径R₁=R₂=100 μm、环腔传输损耗系数t₁=t₂=0.95的情况下, 针对环与环之间耦合器和环与波导之间耦合器透射系数对群有效折射率的不同影响, 得到了最大群有效折射率的产生条件. 采用文中参数(R=100 μm, t=0.95)计算的单环谐振式陀螺灵敏度为(10⁴-10⁵)°/h, 而双环级联谐振系统理论灵敏度能够达到10 °/h. 该研究对微环耦合谐振腔在角速度检测上的应用有重要的意义.     

Dispersion Characteristics of Waveguide Arrays in Optical Spectrum Analyzers

Formulas for calculating the spectral characteristics of waveguide arrays, which are incorporated into waveguide spectrum analyzers based on planar waveguides, channel waveguides, and fiber optical waveguides, are derived taking into account the contribution of both the waveguide dispersion and the material dispersion to the dispersion factor. These formulas are used to study the dependence of the dispersion factor on the waveguide-system parameters for specific models of waveguide arrays. It is shown that consideration of contributions of the waveguide dispersion and material dispersion can affect profoundly the spectral characteristics of waveguide arrays.     

A novel accelerometer based on microring resonator

A novel microring resonator accelerometer is proposed. It is realized by a suspended straight waveguide coupled with a microring resonator. Under the external acceleration, the coupling coefficient is a function of gap spacing between the two waveguides. The mathematical model of the sensing element is established. Both the finite element method and coupled mode theory are adopted to analyze and optimize the proposed structure. Simulation results show that the mechanical sensitivity is 0.015 μm/g with the working frequency below 500 Hz and cross-axis sensitivity less than 0.001%, which is promising in seismic related applications.     

Optimization of optical ring resonator devices for sensing applications

The Q-factor of an optical resonance device determines the width of its transmission resonances. For this reason, in sensing applications of optical resonators, it is commonly assumed that the Q-factor fully determines resonator sensitivity. Practically, the latter is not exactly correct. In this Letter, the parameters responsible for the sensitivity of resonance devices (i.e., the steepness and the sharpness of the transmission resonance) are analyzed. It is shown that, for given intrinsic losses of a single ring resonator sensor, the slope of the resonance is largest if its extinction ratio is 9.5 dB, while the resonance is sharpest if its extinction ratio is 6 dB. For a sensor consisting of several identical ring resonators coupled to a bus waveguide, the largest slope and sharpness parameters correspond to the extinction ratios of ~9 dB and ~4.5 dB, respectively. The determined optimum parameters can be achieved by tuning the coupling between the resonator rings and the waveguide.     

Single-photon all-optical switching using coupled microring resonators

We study the nonlinear phase response of a microring resonator coupled to a bus waveguide and the use of this nonlinear phase shift to store information in the microring resonator and enhance the switching characteristics of a Mach-Zehnder interferometer (MZI). By introducing coupling between adjacent microring resonators, the switching characteristics of the MZI can be exponentially enhanced as a function of the number of microring resonators, when compared to the linear enhancement for uncoupled resonators. With only a few moderate-finesse microring resonators, the switching power can be reduced to attowatt level, allowing for photonic switching devices that operate at single-photon level in ordinary optical waveguides.      

Coupled magnetic resonator optical waveguides

Optical resonators are important devices that control the properties of light and manipulate light–matter interaction. Various optical resonators are designed and fabricated using different techniques. For example, in coupled resonator optical waveguides, light energy is transported to other resonators through near‐field coupling. In recent years, magnetic optical resonators based on LC resonance have been realized in several metallic microstructures. Such devices possess stronger local resonance and lower radiation loss compared with electric optical resonators. This study provides an overall introduction on the latest progress in coupled magnetic resonator optical waveguide (CMROW). Various waveguides composed of different magnetic resonators are presented and Lagrangian formalism is used to describe the CMROW. Moreover, several interesting properties of CMROWs, such as abnormal dispersions and slow‐light effects, are discussed and CMROW applications in nonlinear and quantum optics are shown. Future novel nanophotonic devices can be developed using CMROWs.     

基于光纤反射腔的高灵敏电流传感器方案

提出了一种基于平面Y分支波导与法拉第旋镜的高灵敏度光纤电流传感器结构方案。利用两个法拉第旋镜与平面Y分支波导构成一个光纤反射腔,通过光在腔中的多次反射来增加待测电流导致的传感光纤中的法拉第相移,从而实现对微弱电流的测量。该结构方案中首次采用了平面Y分支光波导,从而可降低光路系统损耗,增加灵敏度,为微弱电流测量的工程化提供了一种可行的方法。     

Silica waveguide ring resonators with multi-turn structure

Optical waveguide ring resonator is the basic element of resonator integrated optic gyro (RIOG). In this paper, we report a novel configuration of optical waveguide ring resonator using a multi-turn structure. The characteristic of the light propagating across the crossed waveguides is analyzed using the finite difference beam propagation method. The relationship between the propagation loss and the intersection angle for arbitrary intersecting angles has been analyzed. Some crossed waveguides are fabricated in silica waveguides to verify the theoretical results. On this basis, the influences of the loop numbers and the excess loss of the crossed waveguide on the limited sensitivity of the RIOG have been analyzed. There is a critical intersection angle for certain resonator, only when the intersection angle is bigger than the critical angle, the gyro sensitivity can be improved by increasing the loop numbers. This will be helpful to how to determine the optimum length in resonator for its application in RIOG.     

空芯光波导在光谱气敏检测中的应用

空芯光波导(HWG)用于光谱气体检测中,既可以实现光路的传输,又可以充当气体样品池实现长光程高灵敏度测量,具有体积小,响应时间快、成本低、光路稳定灵活等优点。介绍了基于镀银/碘化银的空芯光波导(Ag/AgI-HWG)、光子带隙空芯光波导(PBG-HWG)和基片集成空芯光波导(iHWG)等类型的空芯光波导,并总结了近年来空芯光波导在光谱气敏检测中的研究及进展,梳理了其应用方式及应用领域。研究表明,空芯光波导替代传统的气体池与傅里叶变换红外光谱(FTIR)、激光吸收光谱和拉曼光谱等不同的光谱技术结合已取得一系列成果,且已经应用于环境监测、呼气诊断和工业过程检测和控制等领域。其中,基于中红外激光吸收光谱的空芯光波导传感器组成相对简单,成本较低,与各类光波导的兼容性和环境适应性较强,发展前景较好。总之,随着激光技术、光波导技术和光谱技术的发展,基于空芯光波导的光谱气体检测正在迅速发展,并逐步由实验室走向现场应用。     

基于十字连通形环形谐振腔金属-介质-金属波导的折射率传感器和滤波器

提出了由十字连通形环形谐振腔耦合两个金属-介质-金属(metal-insulator-metal, MIM)波导的结构,并用有限元法数值研究了表面等离极化激元在结构中的传输特性.通过对透射谱的研究,系统地分析了MIM结构的传感特性.结果表明,在透射光谱中有三个共振峰,即存在三种共振模式,其中透射峰与材料的折射率呈线性关系.通过对结构参数的优化,得到了折射率灵敏度(S)高达1500 nm/RIU的理论值,相应的传感分辨率为1.33×10~(-4)RIU.更重要的是,灵敏度不受结构参数变化的影响,这意味着传感器的灵敏度不受制造偏差的影响.此外,谐振波长与环形腔中心半径成线性关系,该器件在较大波长范围内实现可调谐带通滤波.透射强度随着波导与环形腔间距的增大而减小,透射带宽同时减小,因此,可以通过控制环形腔与波导的耦合距离来调谐透射强度及透射带宽.研究结果对高灵敏度纳米级折射率传感器和带通滤波器的设计以及在生物传感器方面的应用都具有一定的指导意义.