A new solving method of non-uniform dielectric planar waveguide

A new solving method of non-unifrom dielectric planar waveguide is presented in this paper. By applying this method to solving the problem of planar dielectric waveguide with arbitrary refractive index variation, the advantage of this new method is more evident. By dividing the waveguide into proper numbers and thickness of layers, we can transform the problem of non-uniform dielectric planar waveguide into the multilayer dielectric waveguide to calculate its propagation constantβ.     

基于平板波导的小型红外光栅光谱仪光学设计

为实现红外光谱仪器的小型化,通过分析现有小型光谱仪,提出了一种基于平板波导的小型红外光栅光谱仪的设计方法。平板波导光谱仪的小型化原理与一般的微小型光谱仪不同。在平板波导光谱仪中,光束被限制在一层薄薄的平板波导介质中传播,看起来像是整个光学系统被压扁了。在垂直于平板波导的方向上光学元件的尺寸可以做到很小,从而显著减小光学系统的尺寸。该系统的设计可分为Czerny-Turner结构设计、波导结构设计。先根据像差理论设计Czerny-Turner结构,目标是保证光谱分辨率及校正像差;然后根据几何光学理论设计波导结构,包括平板波导和两个柱面透镜,目标是压缩光束并校正像散;最后将它们输入Zemax软件中进行综合优化,以获得最优的光学系统。据此方法设计了一个平板波导红外光栅光谱仪,工作波段为8~12 μm,数值孔径为0.22,采用线阵探测器。通过Zemax软件对结果进行分析和评价,表明仪器光学系统的尺寸为130 mm×125 mm×20 mm,工作波段内光谱分辨率达到80 nm,满足设计指标要求。证明了该优化设计方法是可行的,所得系统尺寸小、性能高。     

Optical properties of He+-implanted and diamond blade-diced terbium gallium garnet crystal planar and ridge waveguides

Terbium gallium garnet (Tb₃Ga₅O₁₂, TGG) crystal can be used to fabricate various magneto-optical devices due to its optimal Faraday effect. In this work, 400-keV He⁺ ions with a fluence of 6.0×10¹⁶ ions/cm² are irradiated into the TGG crystal for the planar waveguide formation. The precise diamond blade dicing with a rotation speed of 2×10⁴ rpm and a cutting velocity of 0.1 mm/s is performed on the He⁺-implanted TGG planar waveguide for the ridge structure. The dark-mode spectrum of the He⁺-implanted TGG planar waveguide is measured by the prism-coupling method, thereby obtaining the relationship between the reflected light intensity and the effective refractive index. The refractive index profile of the planar waveguide is reconstructed by the reflectivity calculation method. The near-field light intensity distribution of the planar waveguide and the ridge waveguide are recorded by the end-face coupling method. The He⁺-implanted and diamond blade-diced TGG crystal planar and ridge waveguides are promising candidates for integrated magneto-optical devices.     

Shift multiplexing by planar waveguide referencing

We present a new method with which to implement shift multiplexing by planar waveguide referencing. In this method, a planar waveguide is used to steer the reference beam, and we implement shift multiplexing by shifting the recording medium. A spatial selectivity as high as 1.1 microm is obtained. By using waveguide referencing we can make a compact and simple holographic system.     

Derivative free method for computing modes of multilayer planar waveguide

A technique to solve generalized dispersion equation of multilayer planar waveguide has been demonstrated to obtain all the expected guided modes. The solution is based on the derivative free method for computing the zeros of an analytical function in complex plane. The derivative free method extracts the roots which are very close to actual zeros of the function. Roots are further refined using the robust iteration method to achieve the desired accuracy. Application of the proposed method has been verified by solving the modes of a variety of structures including lossless structure, leaky structure, quantum well waveguide, active waveguide, ARROW waveguide and metal clad waveguide. The method is efficient and computes all modes of planar waveguide with high accuracy.     

An He-implanted optical planar waveguide in an Nd:YGG laser crystal preserving fluorescence properties

We report the formation of a planar waveguide in an Nd:YGG laser crystal by low-energy He-ion implantation at liquid nitrogen temperature (77 K). The optical properties are measured by the prism coupling and end-face coupling methods, the absorption properties the waveguide and Nd:YGG substrate are obtained. The fluorescence spectrums are investigated by confocal methods. The experimental results revealed that the planar waveguide preserved the absorption and fluorescence properties of the Nd:YGG laser crystal. Thus, the planar waveguide formed by the ion implantation method is a promising candidate in waveguide lasers.     

多层介质波导的一种新方法及其在非均匀介质平面光波导中的应用

本文提出求解多层介质平面光波导的一个简单而直接的方法。将其应用于非均匀平面光波导,可以求解任意折射率分布和TM模问题。以抛物线型和指数型分布为例,说明只要分层数目足够多,本文介绍的方法可以达到任意精度。     

基于平面波导激励的修正长程表面波的传感器研究

为了解决传统的强度检测型波导激励的表面等离子体共振传感器灵敏度不高的缺点,研究平面波导激励的介质膜-金属-被测介质的可激发修正的长程表面等离子体波结构。采用离子交换的方法制备折射率可用费米函数拟合的平面波导,研究了离子交换时间对平面波导的模数及等效折射率等特性的影响,为激励波导的优化设计提供有效依据。采用制备的平面波导激励介质膜-金属-被测介质的非对称结构,研究金属材质、介质膜厚和金属膜厚等因素对修正的长程表面等离子体波特性的影响,对被测溶液的折射率进行检测。实验结果表明,其灵敏度为传统的强度检测型表面等离子体共振传感器的6倍,并且具有较好的线性关系。     

Coupling characteristics of a three channel waveguide directional coupler

We develop an accurate analysis for a three channel waveguide directional coupler which takes the effect of corner regions into account through the first order perturbation theory. The applicability of the earlier approaches namely (i) effective-index method (ii) planar waveguide approximation for such couplers has also been discussed. It is found that while the effective-index approach used by earlier authors underestimates the coupling length, the planar waveguide approximation overestimates the same.     

Multi-layer cladding leaky planar waveguide for high-power applications

We design a multi-layer cladding large-core planar waveguide that supports a single guided mode. The waveguide works on the principle of higher-order mode discrimination. The cladding of the waveguide is formed by alternate low- and high- index regions, which helps leaking out of higher-order modes while retaining the fundamental mode over the entire length of the waveguide. The structure is analyzed by the transfer-matrix method and the leakage losses of the modes have been calculated. We show that a waveguide formed in silica with numerical aperture 0.24 and core width 10 μm can be designed to exhibit single-mode operation at 1550-nm wavelength. Such a structure should find applications in high-power planar waveguide lasers and amplifiers.     

迭代法重建平板光波导折射率分布

提出了一种用于重建渐变折射率平板光波导折射率分布的方法,这种方法通过数值法求解亥姆霍兹方程．从光波导的低阶模开始采用迭代法顺次对各个模式对应的“转折点”位置进行校正．并多次重复迭代以消除“转折点”外折射率分布的变化对相应模式“转折点”位置的影响。借助WKB近似原理说明了这种方法迭代过程中“转折点”坐标的收敛性。对折射率按照指数规律变化的平板光波导的折射率分布重建结果证明这种方法具有较高的精度。分析表明：这种方法克服了WKB法固有的缺陷,即忽略模式“转折点”外折射率分布对相应模式传输常鞋的影响和“转折点”处相移的不确定性,因而比逆WKB法具有更好的自洽性和精确性。     

有限宽平板波导中的克尔空间孤子及全光器件的设计

利用数值模拟的方法研究了倾斜入射的傍轴光束在有限宽非线性平板波导内的传输规律.研究发现,当不同波长相同束宽的光束各以临界功率倾斜入射波导时,如果倾斜角、入射点都一样,它们将沿大致相同的周期性的Z字形路径传输;如果光束功率进一步增大,相邻反射点之间的间距随传输距离有逐渐变大的趋势,Z字形路径不再有严格的周期性;当功率相当大时,光束将沿波导z方向传输,不再在波导的两个边界之间来回反射.利用倾斜入射光束在波导内的传输路径随功率而变的特点,设计了一个功率开关和一个光时分解复用器. 关键词： 空间光孤子 有限宽非线性平板波导 全光器件     

平面光波导结构的FDTD分析

将各向异性理想匹配层(APML)吸收边界条件用于平面光波导结构的时域有限差分法(FDTD)分析中,导出了APML媒质中适用于角域和边缘的通用差分方程,并对平行介质带定向耦合器进行了数值模拟和验证,所得数值解与解析解非常一致.该方法可用于任意复杂结构的平面光波导的计算机辅助设计与分析.     

Planar waveguide lasers and structures created by laser ablation — an overview

The parameters of planar and channel waveguide lasers fabricated by different techniques are reviewed. Materials and properties of thin films used for creation of planar waveguide lasers are summarized. The parameters of active and passive planar waveguides created by the method of pulsed laser deposition and problems of laser deposition are described. The aspects of laser generation of planar waveguide lasers, resonators and channel waveguides are presented. The results of our experiments of laser deposition of thin Ti:sapphire layers and thin layers of Nd:YAG and Nd:YAP are briefly discussed. This work was supported by the grant of Czech Grant Agency No. 102/96/0429.     

K-Na离子交换单模平面波导的制备及其表征

通过K-Na离子交换技术制备了多模玻璃平面波导.采用棱镜耦合技术测量了波导的有效折射率,用IWKB方法拟合得到K-Na离子交换波导的折射率分布符合高斯分布,由色散曲线得到单模波导的制备条件(即扩散深度范围),从而得出单模波导的离子交换时间范围,制备出单模波导,并通过求解WKB色散方程得出单模波导的表面折射率.用普通数码相机,通过对离子交换平面玻璃光波导传输线进行数字成像,根据传输线上的光强分布拟合出光强传输衰减曲线,计算出单模波导的传输损耗大约为0.4 dB/cm.     

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。     

Modal Characterization of a Planar Waveguide in Bismuth Borate Crystal

We report on the fabrication and modal property studies of planar waveguide structure in x-cut bismuth borate biaxial crystal formed by He ion implantation with triple energies. The prism coupling method is used to measure the effective refractive indices of this waveguide. We reconstruct the refractive index distribution of this waveguide by the reflectivity calculation method. Our results indicate that a broadened optical barrier is produced by the multiple He ion implantations. The so-called tunneling effect of the non-stationary mode in this type of barrier waveguide is presented by the well-known finite difference beam propagation method.     

Forward and backward wave propagation in multilayer planar waveguide using metamaterials layer

In this study, an efficient method is discussed to analyze the multilayer planar waveguides with double negative guided (DNG) and double positive material as guiding film. Here, among various lossless multilayer planar waveguide structures, only three layer and five layer structures are discussed. For these structures, guided dispersion characteristic, along with electric field distribution of TM modes are numerically analyzed and compared. This analysis enables an effective comparison of guided modal properties of various modes and results in a better understanding of the multilayer planar waveguide with DNG as guiding film.     

二维光子晶体波导与单模平面介质波导间的喇叭波导接头

提出并优化了用于二维介质柱光子晶体波导与单模平面介质波导对接的基于分布布拉格反射波导的喇叭波导接头，提高了这两种波导之间的传输效率.二维时域有限差分仿真结果表明，在大部分光子晶体波导导模的频谱范围内，传输效率高于98％.传输效率最高可以达到99.85％. 关键词： 光子晶体波导 平面介质波导 时域有限差分     

The Observation of Photorefractive Effect of Prism Coupling in Ion-implanted Fe-doped LiNbO_3 Plannar Waveguide

1.IntroductionTheFe--dopedLithiumNiobate(LiNbO3)crystalhavebeenintensitystudiedbecauseoftheirimprovedphotorefractivepropertiesandutilizationinawiderangeofapplicationsinopticalstorage,opticalphaseconjugationandtwo-andfour--wavemixingtechniques.ThewaveguidefabricatedwithsuchcrystalisdesirablebecauseitprovidescomP8tibilitywithotherminiaturizedintegrateddevicescommonlyusedtoday,particularwithlaserdiodesandfibergeometries.Comparingtootherwaveguidefabricationtechniques,suchasmetaldiffusionorionex…