前馈PMD补偿实验中从偏振度椭球获得差分群时延的研究

运用偏振度(DOP)椭球法从实验的有限样点数据中获得了差分群时延和偏振主态方向,这为前馈补偿实验提供了最关键的技术因素.在实验中获得了偏振主态方向和DGD,而且当DGD较小时,从实验所获得的DGD值与理论模拟的变化趋势基本一致.结果表明当DGD较小时,可以用偏振度椭球法从实验上得到正确的DGD和偏振主态方向.     

基于银纳米链的马赫-曾德干涉仪结构的生物传感器

优化了一种基于表面等离激元银纳米链的马赫-曾德干涉式传感结构.该结构由参考臂、传感臂及纳米线波导构成.纳米线波导由银纳米线包裹一定厚度的硅来构成.引入两条银纳米链分别作为马赫-曾德干涉仪的参考臂和传感臂,并研究所设计结构的传输特性,通过降低传输损耗以提高所设计结构的精确度与灵敏度.相比于两条完全相同的银纳米线作为参考臂和传感臂的情况,在参考臂和传感臂改为银纳米链后,传输特性有明显提高,单位长度损耗明显降低.这是由于银纳米链中的单元结构之间的长程/库仑相互作用增强了结构中的电磁场,进而降低了传输损耗.将两条银纳米链的晶格常数设置为不同的情况,研究发现,在特定的银包硅纳米线的宽度与某些占空比下,含有非对称的银纳米链结构的单位传输损耗小于含有对称的银纳米链结构.由此可以知道,具有小损耗的银纳米颗粒链可以弥补大损耗的银纳米颗粒链的传输损失.利用这个特点,进一步优化设计结构,将一侧银纳米链改为纳米线.改变另一侧银纳米链的晶格常数与占空比,可以发现大多数情况下,这类结构传输特性优于含有两条银纳米链以及含有两条银纳米线的结构.本文的设计结构可以大幅减小传统的马赫-曾德干涉仪的传输损耗,且在结构的制备...     

Entire Transmission in Negative Directions through a Single Layer of Nanorods

We numerically investigate the regulation of beam direction by a single layer of high electrical permittivity nanorods with two kinds of cross-arranged radii. It is found that an oblique incident optical beam transmits more than 95% with a wide range wavelength of 80 nm near 1550 nm in a negative direction. In particular the efficiency can be up to 100% around the wavelength of 1550nm at a wide-range angle. The results are very promising for designing subwavelength optical elements to realize beam steering in optical integrated circuits.     

偏振控制器完成任意偏振态变化的最小自由度研究

偏振控制器(PC)是处理光纤中信号偏振态(SOP)的重要器件,它是偏振模色散(PMD)自适应补偿器的重要组成部分.以两种类型的商用偏振控制器为例,理论和实验证明了转变任意输入态到庞加莱(Poincaré)球上其他任何状态至少需要调整三个自由度而不是两个自由度.因此至少需要控制每一阶段的PMD补偿器中偏振控制器上的三个自由度而不是两个白由度,才能够实现完全的PMD补偿.     

Characteristics of the Coupled-Resonator Structure Based on a Stub Resonator and a Nanodisk Resonator

A coupled-resonator structure consisting of a stub resonator and a nanodisk resonator is proposed and numeri- cally investigated by using a two-dimensional finite element method. Simulation results show that two resonant modes occur in the transmission spectra, and the sharp and asymmetric Fano-lines increase with the wavelength resolution. We also analyze the properties of two resonant modes of the structure and design a similar structure supporting only one resonant mode, which has better wavelength resolution. Our models are important for improving the wavelength resolution in plasmonic devices and the sensitivity in sensors.     

Millimeter Propagation and High Confinement in Rhombus-Based Hybrid Plasmonic Waveguides

A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations show that the present waveguide can achieve the millimeter propagation distance （1244 μm） and deep subwavelength mode area （5.5 × 10-3 μm2）, simultaneously. Compared with the previous hybrid waveguides based on cylinder nanowires or fiat films, the rhombie corner angles enable our waveguide to achieve both longer propagation distance and smaller mode area. This is due to the enhanced coupling between the dielectric guided mode in nanowires and the surface plasmon polariton mode at rhombic surface. Furthermore, the extreme confinement near the rhombic corner angles can strengthen the light-matter interaction greatly and make the present waveguide useful in many applications, such as nonlinear photonics, high-quality nanolazers and nanophotonic waveguides.     

不同调制格式的偏振模色散补偿性能分析

研究了不同调制格式的产生及其偏振模色散补偿性能。首先从实验上得到了不同调制格式的频谱和眼图,并将其输入偏振模色散补偿系统,实现了缓解与补偿的动态结合。其次,从数值上比较和分析了不同调制格式应用于以偏振度做反馈信号的偏振模色散补偿系统后的补偿性能,结果表明,差分相移键控对偏振度的响应度和偏振模色散补偿效果要比传统开关键控好,因此差分相移键控非常适合于以偏振度做反馈信号的偏振模色散补偿系统;而载波抑制码差分相移键控结合了载波抑制码载波抑制特性和差分相移键控的特殊频谱特性,具有最好的偏振模色散补偿效果。     

基于偏振度的偏振模色散补偿中检测信号对不同归零码型的响应研究

从理论上数值分析和比较了一阶和二阶偏振模色散对各种光调制码型（RZ、CSRZ、RZ-DPSK、CSRZ-DPSK）的偏振模色散的影响，结果表明:不同码型的偏振度大不相同，RZ码受偏振度影响最大，CSRZ-DPSK码受二阶偏振模色散的影响最小，在补偿系统中更适合缓解偏振模色散.     

An experiment for obtaining DOP ellipsoid using particle swarm optimization algorithm

The degree of polarization (DOP) ellipsoid can be used as either feedback or feedforward signal for automatic polarization mode dispersion compensation. We have realized the experiment for obtaining DOP ellipsoid from 100 sampling data of output states of polarization using particle swarm optimization (PSO) as ellipsoid data fitting algorithm. It was shown that the PSO algorithm was powerful for ellipsoid data fitting with high precision within 250 ms.     

PSO算法用于WDM系统多信道PMD补偿的研究

根据波分复用（Wavelength Division Multiplexing,WDM）系统多信道偏振模色散（Polarization Mode Dispersion,PMD）的最坏信道补偿方案,将粒子群优化（Particle Swarm Optimization,PSO）算法用于多信道的PMD补偿.在补偿最坏信道的同时,保障了其他信道的性能.并以两信道PMD补偿系统为例进行了数值模拟,得到了很好的补偿效果.