一种新颖的用于光腔模式及光束传输模拟的特征向量法

根据有限元法单元划分的思想，提出了一种新颖的模拟光腔模式及光束传输的特征向量法. 该方法的关键之处在于基于衍射积分理论构造了一种新的光束传输矩阵，通过求解特征矩阵方程可一次性得到谐振腔的一系列特征向量，每一列特征向量即代表了腔镜上光场的一个确定模式的振幅及相位分布. 并可采用该方法模拟光场传输到腔内或腔外任意地方的场分布. 该方法将传统方法中大量的迭代过程转化成为本征积分方程特征向量的求解过程，并与初值取值无关，且可一次性求得多个模式分布，从而可方便地分析谐振腔的模式鉴别能力. 特征向量法对圆形镜共焦 关键词： 谐振腔 特征向量法 模式分布     

多元件谐振腔模式的有限元传输矩阵分析方法

建立了多元件谐振腔本征模的有限元传输矩阵模型。提出了模式计算相对误差概念及相应表达式,该表达式在数值上不受菲涅耳数的影响,能够很好反映有限单元划分方案对不同菲涅耳数的谐振腔的模式计算精度的影响。提出了有限单元划分精细度的概念和相应表达式,用以表征有限单元划分的精细程度。该表达式以菲涅耳数作为有限元传输矩阵法对腔镜单元格数划分的相对要求,用镜面实际划分的单元格数与菲涅耳数的比值来表征有限单元划分的精细程度。分析了不同谐振腔参数变化时模式计算相对误差与有限单元划分精细度的关系,建立了3种不同函数形式的经验表达式,并通过比较拟合残差选择了拟合效果较好的表达式。     

束变换环孔激光谐振腔的设计与分析

分析了束变换环孔激光谐振腔的特点和优势,给出了这种复杂激光谐振腔的设计原理。对采用该方法设计的激光谐振腔空腔模式进行了计算和分析,并使用自行编写的三维光线追迹程序对这种腔的稳定性也进行了研究。结果表明这种谐振腔输出光场分布合理,相传均匀,远场分布接近衍射极限,并且这种腔对于扰动在一定范围内具有抑制能力,是一种研究价值很高的非稳腔。此外针对该腔提出的设计及模式计算方法对其他复杂腔型也具有一定的参考价值。     

光腔模式及光束传输的特征向量算法

发展了一种新颖的适用于光腔模式及光束传输模拟计算的特征向量法.该方法的核心是基于菲涅耳-基尔霍夫衍射积分理论构造了一种新的光腔传输矩阵,通过求解激光谐振腔的本征积分方程,即可一次求解得到表征腔镜上多个光场模式振幅及相位分布的特征向量组;而谐振腔内或腔外任意地方的光场分布,也可采用该方法进行光束传输模拟而求得.对与该方法有关的单元划分、形函数选取、误差及稳定性分析等问题进行了论述,分析表明:合适的单元划分和形函数选取有利于提高计算速度、精度和稳定性.     

交叉柱面镜腔的研究

使用矩阵理论,对两个交叉成任意角度的柱面镜构成的谐振腔作了深入的理论研究.分析了这类光腔的稳定性、模式分布和腔内光束传输特性,并以数值计算例说明.对我们使用交叉柱面镜腔的钕玻璃板条激光器有关的实验结果作了报道和讨论.     

激光非稳腔模式的快速计算方法

对Du Fort-Frankel差分格式用于谐振腔模式计算进行简要分析,以该差分格式为基础,提出基于移动矩阵法的非稳腔模式数值计算快速算法.对空腔共焦非稳腔模式进行数值模拟,将计算结果与参考文献进行对比,两者吻合较好.对有源共焦非稳谐振腔内增益区位置对谐振腔输出功率的影响进行数值计算,结果表明:对于采用共焦非稳腔的大功率激光器,当增益体积一定、小信号增益曲线相同时,随着谐振腔内增益区与凹面镜之间的距离的减小,激光器输出功率会有较为明显的提高.数值算例证明了本文方法的正确性和有效性.     

利用特征向量法分析有源失调腔的2维模场

 利用一种用于光腔模式及光束传输模拟计算的特征向量法计算有源腔的2维失调,通过对谐振腔几何关系的求解,以及对增益进行薄层模型处理,最后利用特征向量法计算有源腔失调后的模式分布,发现失调造成了模式强度分布不均匀,并带来模式阶数的改变。计算了相应的光束质量因子,结果表明:在一定失调范围内,失调可能会带入新的模式竞争;谐振腔在一定范围的失调情况下,各阶模式的光束质量可能变好,也有可能变差,随着模式阶数的增加光束质量整体趋势是越来越差;原来简并的模式可能不再简并。该方法可以为计算失调后谐振腔的模场带来方便。     

孔径光阑输出对太赫兹激光器模式特性的影响

孔径光阑耦合技术是大功率光泵气体太赫兹激光器的一种常用谐振腔设计方法。在不考虑波导对腔内模式形成的影响下,采用传输矩阵的特征向量法,针对孔径光阑耦合太赫兹谐振腔的腔内本征模式以及输出光束特性进行了数值模拟,得到了该种谐振腔在不同g参数下损耗最低的几种本征模式及其相应的衍射损耗;采用衍射积分与矩阵光学结合的方法计算了孔径光阑输出太赫兹激光的光束特性,得到不同本征模式的远场衍射光斑及发散角。研究工作为孔径光阑耦合的气体太赫兹激光器设计提供了理论参考。     

具有二维光子带隙结构的太赫兹谐振腔的谐振特性

采用数值计算方法,模拟了具有二维光子带隙结构的太赫兹频段谐振腔的谐振模式场分布,计算了这种谐振腔的品质因数,详细分析了光子晶体结构、缺陷腔几何参量对谐振特性的影响.计算得到频率落在光子晶体禁带内的单一、高阶谐振模式,且缺陷腔横向尺寸越大,谐振模式的阶数越高.这种谐振腔具有很高的品质因数,腔体的纵向长度对品质因数的影响较大.     

同轴放电环形增益区谐振腔镜面的场分布

 对几类环形增益区谐振腔进行了比较，得出利用谐振腔两镜之一的全工作面输出的新型环形增益区谐振腔是适合的谐振腔。提出了一种计算全工作面输出的同轴放电环形增益区谐振腔镜面场分布的方法，利用几何方法对腔镜镜面进行划分,得出了基于菲涅尔-基尔霍夫衍射积分定理的积分区域，并对该区域进行了有限元划分，应用计算机编程计算出了同轴放电环形增益区谐振腔镜面处的光场分布和相位分布。近场分布在环形区中央部分近似地呈高斯分布，且沿径向出现高阶模场分布特点，沿角向无差别。     

Classifying the transmission resonances of a subwavelength aperture within a thin metallic film by breaking the symmetry

Here by introducing an I-shape structure to break the symmetry of a thin metallic film, the contributions of Fabry–Perot (FP) resonance-like modes and surface plasmon polariton (SPP) resonance-like are determined. The finite difference-time domain (FDTD) simulation is utilized to provide a clear picture of the electromagnetic field distribution and transmission profile. The FP matrix method is employed to specify the contribution of FP resonance. Some of the predicted resonances of the FP matrix method coincide with the simulation result which is labeled as FP resonance-like modes. The remaining resonance modes in transmission profile are considered as SPP resonance-like modes. Our results provide explicit evidence that both FP resonator modes and SPP resonance are responsible for extraordinary optical transmission (EOT) through a subwavelength aperture.     

Simulation of optical field in laser resonators cavity by eigenvector method

In this paper, an Eigenvector method (EM) for the calculation of optical resonator modes and beam propagation is introduced, in which the transit matrix of an optical resonator is obtained by dividing the mirror into finite grids based on the Fresnel–Kirchoff diffractive integral equation. Then, the eigenvectors, representing the multimode characteristics of the resonator, can be calculated by solving the integral matrix eigenequation. The merits of EM include that the considerably simpler procedure of solution of eigenvectors of the matrix eigenequation replaces the complicated iteration in traditional methods, and there is no dependence on the initial field distribution, and a number of modes can be derived once and the discrimination capability of the resonator can be evaluated easily. The examples using EM to simulate con-focal resonators with small or large Fresnel numbers are given, and the calculated results, well matched with Fox–Li method or Lagueree–Gaussian approximation analytical solution, prove that EM is highly feasible and reasonable.     

Dual-band optical filter based on a single microdisk resonator

We propose and experimentally demonstrate a dual-band optical filter based on a single microdisk resonator. An analytical model is built based on the transfer matrix method and is applied to simulate the properties of such a device. Competition and interference of the dual modes in the resonator lead to dual-band filtering with high isolation. As the finite-difference time-domain simulation illustrates, two low-order resonant modes can be effectively triggered by optimizing the waveguide width and spacing gap between the compact resonator and waveguides. In experiment, a double side-coupled microdisk resonator was fabricated on a nanophotonic silicon-on-insulator platform, and dual-band bandpass filtering is realized with an optical isolation higher than 20 dB and an insertion loss lower than 2 dB. The experimental results agree well with our modeling results.     

激光谐振腔自再现模的波型特征

本文用光传输矩阵理论给出分析激光光腔模式波型特性统一处理方法.导出激光谐振腔自再现模的波型函数.讨论了在各类激光谐振腔中激光束的波型特征.     

圆镜共焦腔激光横模的传输矩阵法模拟和分析

共焦腔是一般稳定腔的特例,由于等价性,共焦腔中自再现模的振幅分布、损耗和光斑尺寸常常被用于讨论一般稳定腔。为了分析具有大菲涅尔数的圆镜共焦腔,本文利用传输矩阵方法对腔模进行计算和讨论。研究结果表明:传输矩阵方法的结果与Fox-Li积分迭代法的结果一致,并且传输矩阵方法实用于大菲涅尔数共焦腔。     

Unidirectional excitation of surface plasmon polaritons in T-shaped waveguide with nanodisk resonator

The unidirectional excitation of surface plasmon polaritons (SPPs) in a novel configuration is numerically investigated by the finite-difference time-domain method. It is found that the transmission varies periodically with the increase of distance between the nanodisk resonator and horizontal nanoslit, which can be interpreted by the interference theory. The operating wavelength of this structure can be tuned by altering the refractive index of the nanodisk resonator. This subwavelength-scale structure exhibits high transmission (～58%) due to the constructive interference of the SPP modes, and thus can find important applications on the manipulation of SPP excitation in highly integrated optical circuits.     

一种新型光子晶体双色谐振腔

提出一种新型的光子晶体双色谐振腔,以光学传输矩阵法为基础给出了设计的关键参量及其优化方法,并分析了其物理原理.根据常用的650nm/780nm,532nm/671nm,1079nm/1320nm和1 064 nm/1 319 nm等双色激光谱线,设计了4个光子晶体双色谐振腔结构.这种一维光子晶体谐振腔只需要一个谐振腔,缺陷层两侧周期数为5层时,该腔体总厚度小于5 μm,可获品质因子为103~104,相对带宽为10－4~10－5的双色谱线,且模式纯净,基于基模谐振.     

Field quantization for chaotic resonators with overlapping modes

Feshbach's projector technique is employed to quantize the electromagnetic field in optical resonators with an arbitrary number of escape channels. We find spectrally overlapping resonator modes coupled due to the damping and noise inflicted by the external radiation field. For wave chaotic resonators the mode dynamics is determined by a non-Hermitean random matrix. Upon including an amplifying medium, our dynamics of open-resonator modes may serve as a starting point for a quantum theory of random lasing.