飞秒激光空间选择性诱导玻璃微结构及应用

利用飞秒激光与玻璃的非线性相互作用，可以对玻璃进行空间选择性微观改性与修饰，赋予新的光功能．本文介绍飞秒激光的持点及其对玻璃微结构的改性，以及近年来利用飞秒激光进行玻璃的缺陷控制、光活性离子(稀土、过渡和重金属离子)价态操作、微晶析出与折射率调控及其在光开关、波分复用、波导型有源器件、光子晶体等微光学器件的制备及光学集成领域应用的进展．     

基于非理想克尔介质的弧形波导全光开关

基于非理想克尔介质的弧形波导全光开关     

衰减全反射型聚合物波导光开关

衰减全反射型聚合物波导光开关     

超快非线性干涉仪开关窗口的特性研究

超快非线性干涉仪（UNI）是一种基于半导体光放大器（SOA）的超高速全光开关器件。UNI的开关窗口特性的好坏是评价UNI性能的一个重要指标。文章对单臂结构的UNI的工作原理进行了描述,并用Optisystem 3.0对UNI开关窗口特性进行了仿真模拟,详细分析了延时τ.SOA的偏置电流、控制光功率以及连续光功率等因素对UNI开关窗口的影响,从而为实现最佳的开关窗口提供了一个理论指导。     

聚合物光波导端面磁流变抛光工艺(英文)

光波导端面的表面质量会严重影响光波导器件的光耦合封装性能,耦合封装前必须对波导器件端面进行抛光处理.目前聚合物光波导端面主要依靠传统研磨盘进行抛光处理,该工艺工序复杂、抛光效率低已成为制约聚合物波导器件应用的瓶颈.基于聚合物光波导材料优良的加工特性,通过对比实验提出了聚合物光波导的磁流变端面抛光工艺.采用5μm、0.5μm和1μm粒径的氧化铈抛光粉分别配制研磨盘抛光液及磁流变抛光液对3 mm×3 mm聚合物光波导端面进行抛光实验,发现磁流变加工对聚合物光波导端面进行一次2 m in光栅扫描抛光就具有比传统研磨盘约3 h精、粗抛光较好的端面质量.经过白光干涉仪测量,磁流变抛光后光波导端面表面粗糙度的均方根值达到了2.6 nm,传统端面抛光端面粗糙度均方根值为128.7 nm.通过自动对准耦合平台测试,结果显示通过磁流变端面抛光的光波导的插入损耗由抛光前的32.7 dB降低到了17.8 dB.磁流变抛光方法可以对聚合物光波导端面进行快速、高性能的抛光,在光波导应用领域具有非常广阔的应用前景.     

半导体光放大器的非线性分析

近些年来,在对半导体光放大器的光学非线性特性的研究方面,我们取得很大的进步。一系列很有潜力的应用已经被我们开发出来,包括波长变换、光学多路输出选择器、时钟复原、时空开关、传播补偿等。研究半导体光放大器非线性方面的特性,希望对今后的研究提供帮助。     

光开关在光通信中的应用及其最新进展

光开关是全光通信网的关键器件,在网络出现拥堵时通过自动保护倒换功能为网络预留备份通道.常见的光开关有热光效应光开关,MEMS光开关等.近年来,来自高校的研究人员又提出了基于微流控的波导型光开关.     

玻璃基掩埋式光波导堆栈的制作与表征

在硅酸盐光学玻璃基片上制作了光波导堆栈, 这种光波导堆栈通过Ag⁺/Na⁺熔盐离子交换和电场辅助离子扩散技术顺次制作了两层掩埋式光波导. 对光波导堆栈的横截面显微结构进行了观察, 并对堆栈中两层波导的损耗特性进行了测试. 所获得的光波导堆栈中的上、下两层波导芯部分别位于玻璃表面以下14和35 μm处; 上层光波导芯部尺寸约为12 μm×7 μm; 下层光波导芯部尺寸约为9 μm×8 μm. 通光测试显示两层波导在1.55 μm工作波长下均为单模光波导, 且两者之间没有相互耦合. 损耗测试分析结果显示: 堆栈中两层光波导的传输损耗均约为0.12 dB/cm,与单模光纤之间的耦合损耗分别为0.78和0.73 dB. 分析表明, 这种光波导堆栈在玻璃基集成光芯片的高密度集成方面具有很好的应用前景.     

玻璃光波导研究进展

介绍了目前国际上主要玻璃光波导的研究热点。阐述了制备光波导的晶体材料、玻璃材料和高分子聚合物材料的优缺点。着重阐述了玻璃材料的研究进展,并简要介绍了采用硫卤玻璃制备非线性光波导的诱人前景。     

聚合物通道波导的分析及制备

ＰＤＡ聚合物有较大的三阶非线性极化率和超快的响应特性，是全光器件应用中非常有前景的材料，本文采用有效折射率法分析了下条载聚合物薄膜通道波导的传输特性，讨论了制备单模传输波导的条件及其影响因素，制备了ＰＤＡ薄膜通道波导，并测试了其波导特性。     

Interdigitated electrode-induced phase grating with an electrically switchable and tunable period

A new design for an adjustable electro-optic phase grating inside a waveguide is proposed. The electric field and the refractive-index distribution induced inside a waveguide by voltage applied to double-sided periodic interdigitated electrode arrays are calculated rigorously on the basis of an original analytical technique. The modeling was carried out with the Mathcad software. It is shown that the fundamental periodicity of the induced grating inside the waveguide can be switched between l and 2l by application of the appropriate voltage, where l is the spatial periodicity of the interdigitated electrodes. One can also fine tune the peak grating reflectivity by changing the constant component of the induced refractive index with the help of the constant component of the electric field inside the waveguide. The suggested design can be used as a basic idea for a variety of optical communication networking applications, including switching, modulation, deflection, and data processing.     

Adiabatic polymer-glass-waveguide all-optical switch

We propose an adiabatic all-optical switch that is composed of an asymmetric Y-branch ion-exchanged glass waveguide with a strip of nonlinear polymer loaded on top of one branch. The properties of nonlinear wave propagation in the device are investigated in detail. By extending the effective-index method to the analysis of nonlinear waveguides, we calculate the nonlinear dispersion curves in successive sections to explain the evolution of normal modes in the device. As the multivalued propagation constants exist in the tapered directional coupler region, the device possesses an abrupt switching behavior and nonreciprocal properties. To demonstrate nonlinear switching behaviors in the Y-branch waveguide further, we employ a beam propagation method to simulate optical-field propagation. The inputs by three different ports are investigated, and the results agree well with the dispersion-curve analysis.     

Polymer-based waveguides and optical switching

The fabrication and linear optical characterization of a Bragg reflector in a planar polymeric waveguide, suitable for an all-optical switching device, is reported. Surface corrugation gratings with a grating constant of 349 nm were produced in different polymeric films of poly(phenylene-vinylene), polydiacetylene and polystyrene by excimer laser photoablation. Furthermore, the gap in the linear transmission spectrum of the modulated waveguide was measured and compared with the result of numerical simulations. A good agreement can only be found if a non-uniform grating with a small chirp is assumed. This small deviation from the uniform grating cannot be resolved with a scanning electron microscope. However, this linear optical investigation helps to further improve the fabrication process and opens the possibility to yield a well-defined grating with a prescribed modulation strength, which is a vital requirement for the proper operation of a nonlinear all-optical switch.     

新型光缓存器及2×622Mb／sATM光交换系统

给出了一种新型的光缓存器的结构，以解决在ＡＴＭ光交换中的信元碰撞问题。这种缓存器是由光纤延迟线、光波导开关阵及非线性半导体光放大器构成。文中还报告了一种用于交换各用户不同速率的信元（可达６２２Ｍｂ／ｓ）的ＡＴＭ光交换实验系统，系统的总容量为了１．２Ｇｂ／ｓ。     

Integrated Mach-Zehnder-based 2x2 all-optical switch using nonlinear two-mode interference waveguide

The Mach-Zehnder interferometer (MZI) is a common structure for integrated all-optical switches. We proposed and designed an all-optical 2x2 switch that is based on the MZI, multimode interference, and a nonlinear two-mode interference waveguide. The beam propagation method is used to simulate and analyze the device. The results show that the switching action is done properly.     

An integrated electrochromic nanoplasmonic optical switch

We demonstrate an electrochemically driven optical switch based on absorption modulation of surface plasmon polaritons (SPPs) propagating in a metallic nanoslit waveguide containing nanocrystals of electrochromic Prussian Blue dye. Optical transmission modulation of ～96% is achieved by electrochemically switching the dye between its oxidized and reduced states using voltages below 1 V. High spatial overlap and long interaction length between the SPP and the active material are achieved by preferential growth of PB nanocrystals on the nanoslit sidewalls. The resulting orthogonalization between the directions of light propagation and that of charge transport from the electrolyte to ultrathin active material inside the nanoslit waveguide offers significant promise for the realization of electrochromic devices with record switching speeds.     

Ultralow voltage resonant tunnelling diode electroabsorption modulator

Embedding a double barrier resonant tunnelling diode (RTD) in a unipolar InGaAlAs optical waveguide gives rise to a very low driving voltage electroabsorption modulator (EAM) at optical wavelengths around 1550 nm. The presence of the RTD within the waveguide core introduces high non-linearity and negative differential resistance in the current-voltage (I-V) characteristic of the waveguide. This makes the electric field distribution across the waveguide core strongly dependent on the bias voltage: when the current decreases from the peak to the valley, there is an increase of the electric field across the depleted core. The electric field enhancement in the core-depleted layer causes the Franz-Keldysh absorption band-edge to red shift, which is responsible for the electroabsorption effect. High-frequency ac signals as low as 100 mV can induce electric field high-speed switching, producing substantial light modulation (up to 15 dB) at photon energies slightly lower than the waveguide core band-gap energy. The key difference between this device and conventional p-i-n EAMs is that the tunnelling characteristics of the RTD are employed to switch the electric field across the core-depleted region; the RTD-EAM has in essence an integrated electronic amplifier and, therefore, requires considerably less switching power.     

Modeling liquid-crystal devices with the three-dimensional full-vector beam propagation method

Simulation of light propagation within nematic liquid-crystal (LC) devices is considered, of which the director is aligned normal to the z axis. A three-dimensional full-vector finite-difference beam propagation method for an anisotropic medium is presented and an alternating direction implicit scheme is adopted. Simulations of light propagation in a bulk polarization converter, a waveguide with a LC covering layer, and an integrated polarization splitter and optical switch are presented. Comparison with an existing simulation method is carried out for beam behavior within the bulk polarization converter. The effect of strong surface anchoring of a LC cell on the beam behaviors within the integrated switch is also demonstrated.     

Design and analysis of hybrid optical and electronic buffer based optical packet switch

Optical packet switching has the potential to be used as next generation data transfer technology. This paper, introduces an Arrayed Waveguide Gratings (AWG) switch where hybrid buffer (electronic + optical) is used for the buffering of contending packets. Power budget analysis has been carried out under various switch designs. Comparison of optical and electronic buffering is done in terms of power required for the correct operation of the switch. Energy consumption per bit is also evaluated for both optical and electronic buffers for various buffering time ranges from nano-seconds to milli-seconds. In the switch analysis it has been found that, amplified switch requires five times less power, in comparison to un-amplified switch for correct operation. Energy consumption analysis reveals that for shorter duration storage, optical buffer would be a better choice.     

All-optical switch using optically controlled two mode interference coupler

In this paper, we have introduced optically controlled two-mode interference (OTMI) coupler having silicon core and GaAsInP cladding as an all-optical switch. By taking advantage of refractive index modulation by launching optical pulse into cladding region of TMI waveguide, we have shown optically controlled switching operation. We have studied optical pulse-controlled coupling characteristics of the proposed device by using a simple mathematical model on the basis of sinusoidal modes. The device length is less than that of previous work. It is also seen that the cross talk of the OTMI switch is not significantly increased with fabrication tolerances (±δw) in comparison with previous work.