光开关及其在全光网中的应用

光开关是完成全光交换的核心器件 ,光开关的研究日益成为全光通信领域关注的焦点。从光开关的性能指标开始系统介绍了光开关的类型 ,深入探讨了光开关构成的全光交换机的结构原理。随着数据网络的迅速发展 ,光开关将在全光网络中得到广泛的应用     

40 Gbps All‐Optical 3R Regeneration and Format Conversion with Related InP‐Based Semiconductor Devices

We report an experimental demonstration of 40 Gbps all‐optical 3R regeneration with all‐optical clock recovery based on InP semiconductor devices. We also obtain all optical non‐return‐to‐zero to return‐to‐zero (NRZ‐to‐RZ) format conversion using the recovered clock signal at 10 Gbps and 40 Gbps. It leads to a good performance using a Mach‐Zehnder interferometric wavelength converter and a self‐pulsating laser diode (LD). The self‐pulsating LD serves a recovered clock, which has an rms timing jitter as low as sub‐picosecond. In the case of 3R regeneration of RZ data, we achieve a 1.0 dB power penalty at 10^?9 BER after demultiplexing 40 Gbps to 10 Gbps with an eletro‐absorption modulator. The regenerated 3R data shows stable error‐free operation with no BER floor for all channels. The combination of these functional devices provides all‐optical 3R regeneration with NRZ‐to‐RZ conversion.     

与偏振相关和无关的4×4自由空间光开关

设计了一种由相位型空间光调制器（PSLM）、偏振光分束器（PBS）、反射镜、半波片（HWP）和四分之一波片（QWP）构成的2×2光开关。该光开关所用器件少,具有结构紧凑规整、功能的实现与信号光的偏振态无关以及可以完成双向交换等特点。在此基础上通过2×2光开关的级联,设计了一种与偏振无关的4×4光开关的实验模块,根据其路由控制表对该实验模块功能的实现进行了分析。为与之作比较,还提出了一种与偏振相关的4×4光开关,该光开关利用对信号光偏振态的控制进行路由选择,以实现所需的交换和排序。     

光控光开关的研究进展

对前人提出了多种光开关的方案和最新研究成果进行了概括和总结,按照光开关所能处理的信号类型,将其分为两类,即基于二光平的光控光开关和基于ＲＺ码（弧子）的光控光开关,分析和研究了其工作原理和开关特性,对两类光开关的性能进行了比较。     

16QAM/PPM光标记交换系统的仿真研究

提出一种脉冲位置调制光标记(PPM)与正交幅度调制(QAM)净荷相结合的光标记交换系统。利用仿真对携带40Gbit/s 16QAM净荷和2.5Gbit/s 2PPM标记的系统传输特性进行验证。通过优化系统频率间隔,得到BER=10-9时,标记和净荷的接收灵敏度与光信噪比(OSNR)分别为-28.51dBm/13.65dB和-22.03dBm/15.02dB。经96km光纤传输后,传输代价均未超过1.5dB。结果证明:16QAM/2PPM光标记交换系统具备良好的传输特性。     

Filter‐Free Wavelength Conversion Using Mach‐Zehnder Interferometer with Integrated Multimode Interference Semiconductor Optical Amplifiers

We propose a filter‐free wavelength conversion using a Mach‐Zehnder interferometer with monolithically integrated 2×2 multimode interference semiconductor optical amplifiers (MMI‐SOAs). The device has been optimized by considering a non‐homogeneous carrier distribution due to the self‐imaging properties of the MMI‐SOA. Static measurements show an extinction ratio of up to 18 dB and an input signal rejection ratio of up to 20 dB.     

Soft‐State Bandwidth Reservation Mechanism for Slotted Optical Burst Switching Networks

This paper proposes a novel transport network architecture for the next generation network (NGN) based on the optical burst switching technology. The proposed architecture aims to provide efficient delivery of various types of network traffic by satisfying their quality‐of‐service constraints. To this end, we have developed a soft‐state bandwidth reservation mechanism, which enables NGN transport nodes to dynamically reserve bandwidth needed for active data burst flows. The performance of the proposed mechanism is evaluated by means of numerical analysis and NS2 simulation. Our results show that the packet delay is kept within the constraint for each traffic flow and the burst loss rate is remarkably improved.     

Priority‐Based Duplicate Burst Transmission Mechanism in Optical Burst Switching Networks

This paper proposes a priority‐based duplicate burst transmission mechanism in an optical burst switching network to enhance the probability of successful reception of bursts. The performance of the proposed mechanism is evaluated by NS2 simulations. Our results show that the burst loss rate is improved especially under light traffic loads.     

自由空间与偏振无关的1×N和N×1光开关设计

基于光开关在全光通信和光互连网络中的重要作用，设计了由偏振光分束器（PBS）、相位型空间光调制器（PSLM）和反射镜构成的1×N和N×1光开关模块，其中N＝2m，m＝1，2，3…。该设计利用PSLM对信号光偏振态的控制，在自由空间实现信号的路由和切换，信号光的P光分量和S光分量同时参与工作，并在输出端口重新会合，因此光开关表现出与信号光偏振态无关的特点。同时，该光开关所用器件少，具有结构简单紧凑、控制方便灵活和操作迅速快捷等特点，而且具有很强的重构与升级能力，对于构建大规模的交换矩阵具有一定的作用。     

Polymer 1×2 Thermo‐Optic Digital Optical Switch Based on the Total‐Internal‐Reflection Effect

This letter presents a polymer 1×2 thermo‐optic total‐internal‐reflection digital optical switch (TIR‐DOS) with an index contrast of 1.5%‐Δ operating at low power consumption. The structure of our 1×2 TIR‐DOS was created by adding a reflection port to that of a conventional multimode filtering variable optical attenuator. To improve the total‐internal‐reflection efficiency, a heater offset was applied to the crossing region of multimode waveguides of the TIR‐DOS. The fabricated 1×2 TIR‐DOS shows a low electrical power consumption of 18 mW for an on‐off ratio of 35 dB.     

国内MOEMS光开关的研究现状

阐述了国内MOEMS光开关的研制现状,列举了国内正在研制的各种MOEMS光开关的结构和性能参数,并且分析了影响光开关性能的各种因素。     

Pump–Push–Probe for Ultrafast All‐Optical Switching: The Case of a Nanographene Molecule

In the last two decades, the three‐beam pump–push–probe (PPP) technique has become a well‐established tool for investigating the multidimensional configurational space of a molecule, as it permits disclosure of precious information about the multiple and often complex deactivation pathways of the excited molecule. From the spectroscopic point of view, such a tool has revealed details about the efficiency of charge pair generation and conformational relaxation in π‐conjugated molecules and macromolecules. In addition, PPP is effectively utilized for modulating the gain signal in conjugated materials by taking advantage of the spectral overlap between stimulated emission and charge absorption in those systems. However, the relatively low stability of conjugated polymers under intense photoexcitation is a crucial limitation for their real employment in plastic optical fibers (POFs) and for signal control applications. Herein, the role of PPP for achieving ultrafast all‐optical switching in π‐conjugated systems is highlighted. Furthermore, new experimental data on optical switching of a newly synthesized nanographene molecule, namely dibenzo[hi,st]ovalene (DBOV), is reported. The superior environmental and photostability of DBOV and, in general, of graphene nanostructures can represent a great advantage for their effective applications in POFs and information and communications technology.     

An All‐Optical Gain‐Controlled Amplifier for Bidirectional Transmission

A novel all‐optical gain‐controlled (AOGC) bidirectional amplifier is proposed and demonstrated in a compact structure. The AOGC function using fiber Bragg grating (FBG) pairs controls both directional signals independently, and combinations of optical interleavers and isolators suppress Rayleigh backscattering (RB) noise. The amplifier achieves high and constant gain with a wide dynamic input signal range and low noise figure. The performance does not depend on the input signal conditions, whether static‐state or transient signals, or whether there is symmetric or asymmetric data traffic on bidirectional transmission. Transmission comparison experiments between invariable symmetrical and random variable asymmetric bidirectional data traffic verify that the all‐optical gain control and bidirectional amplification functions are successfully combined into this proposed amplifier.     

Strategies for Fast‐Switching in All‐Polymer Field Effect Transistors

Low‐cost printable field effect transistors (FETs) are typically associated with slow switching characteristics. Dynamic response of polymer field effect transistors (PFETs) is a manifestation of time scales involved in processes such as dielectric polarization, structural relaxation, and transport via disordered‐interfacial states. A range of dielectrics and semiconductors are studied to arrive at a parameter which serves as a figure of merit and quantifies the different processes contributing to the switching response. A cross‐over from transport limiting factors to dielectric limiting factors in the dynamics of PFETs is observed. The dielectric limited regime in the PFET dynamics is tapped in to explore high speed processes, and an enhancement of switching speed by three orders of magnitude (from 300 μs to 400 ns) is observed at channel lengths which can be accessed by low cost printing methods. The device structure utilizes polymer‐ferroelectrics (FE) as the dielectric layer and involves a fabrication‐procedure which assists in circumventing the slow dynamics within the bulk of FE. This method of enhancing the dynamic response of PFETs is universally applicable to all classes of disordered‐FE.     

垂直腔半导体光放大器双稳及逻辑特性的理论研究

基于垂直腔半导体光放大器（VCSOA）双稳模型，从数值上分析了VCSOA的双稳条件、双稳控制以及双稳环简并下的AND逻辑实现．结果表明，在阈值附近（大于阈值的93%）和初始相位失谐量为负的情况下，输出光功率出现双稳态．偏置电流为阈值的98%时，输入光功率在5.5μW和2.2μW处发生上下跳变的结果与实验报道结果吻合得较好．同时，从理论上给出了偏置电流、相位失谐量、线宽展宽因子、顶端面反射率等控制参数对VCSOA开关功率、跳变点、双稳环宽和环宽简并以及对比度的影响规律．     

混洗网络中光开关矩阵研究

基于偏振控制技术,利用偏振光分束器和位相型空间光调制器构建1×2和2×1的节点开关单元,节点开关单元各端口间按照特定的映射规则和连接关系以光纤实现互连,从而得到一种新型的4×4光开关矩阵.该 4×4光开关矩阵利用位相型空间光调制器对信号光偏振态的控制实现路由,通过对其各输入端口光信号路由状态的分析表明,它可以完成信号光点对点的全排列无阻塞的输出与交换,同时,还具备部分的多点组播功能.该矩阵开关具有交换速度快、插入损耗小、串话低、性能稳定等特点,对于构建大规模的光互连网络具有一定的帮助.     

Thermomechanically Triggered Two‐Stage Pattern Switching of 2D Lattices for Adaptive Structures

Pattern switching (or transformation) widely exists in the activities of various creatures and plays an important role in designing adaptive structures in modern materials. Utilizing the glass transition behavior in amorphous polymers, thermomechanically triggered two‐stage pattern switching of 2D lattices is achieved, where components made of an amorphous polymer and a flexible elastomer are interconnected in predesigned layouts. Upon loading at room temperature, the elastomer is far more flexible than the amorphous polymer and the lattice switches into one pattern. With temperature increasing, the modulus of the amorphous polymer decreases due to glass transition. Under the proper choice of amorphous polymer whose storage modulus can decrease to below the modulus of the elastomer, a change in the relative stiffness can be achieved and can switch the overall pattern from one to another while maintaining the external load. Both the experimental and computational studies are carried out to investigate the switching mechanism. Several periodic structures are fabricated to demonstrate several switched patterns. Particularly, a proof‐of‐concept smart window design is fabricated to explore the potential engineering applications.     

Broadband,High‐Speed,and Large‐Amplitude Dynamic Optical Switching with Yttrium‐Doped Cadmium Oxide

Transparent conducting oxides, such as doped indium oxide, zinc oxide, and cadmium oxide (CdO), have recently attracted attention as tailorable materials for applications in nanophotonic and plasmonic devices such as low‐loss modulators and all‐optical switches due to their tunable optical properties, fast optical response, and low losses. In this work, optically induced extraordinarily large reflection changes (up to 135%) are demonstrated in bulk CdO films in the mid‐infrared wavelength range close to the epsilon near zero (ENZ) point. To develop a better understanding of how doping level affects the static and dynamic optical properties of CdO, the evolution of the optical properties with yttrium (Y) doping is investigated. An increase in the metallicity and a blueshift of the ENZ point with increasing Y‐concentrations is observed. Broadband all‐optical switching from near‐infrared to mid‐infrared wavelengths is demonstrated. The major photoexcited carrier relaxation mechanisms in CdO are identified and it is shown that the relaxation times can be significantly reduced by increasing the dopant concentration in the film. This work could pave the way to practical dynamic and passive optical and plasmonic devices with doped CdO spanning wavelengths from the ultraviolet to the mid‐infrared region.     

2D Tellurium Based High‐Performance All‐Optical Nonlinear Photonic Devices

Tellurium (Te), as one of the rarest stable solid elements far more common in the universe than on earth, is a p‐type semiconductor with excellent optical properties. Herein, a novel two‐dimensional (2D) Te nanosheets (Ns)‐based air‐stable nonlinear photonic devices: all‐optical switcher and photonic diode, owing to its strong light–matter interaction in the visible‐to‐infrared band are reported. The findings validate that the proposed photonic diode can be utilized for the function of nonreciprocal light propagation in optical telecommunications or integrated photonics. Moreover, 2D Te‐based light‐modulate‐light system is successfully designed to realize “ON” and “OFF” modes for all‐optical switching operation. This work highlights a good promise of 2D Te in the field of nonlinear photonics, leading to an important step toward 2D Te‐based advanced photonics devices. The versatile solution process allows a universal access of 2D Te as a new 2D material in a wider range of photonics device applications such as, detector, modulator, switcher, etc.     

Low‐Power and High‐Contrast Nanoscale All‐Optical Diodes Via Nanocomposite Photonic Crystal Microcavities

A novel nanoscale integrated all‐optical diode is reported, realized by combining the strong plasmonic responses of gold nanoparticles with the all‐optical tunable properties of polymeric photonic crystal microcavities. Non‐reciprocal transmission properties are achieved based on the effect of surface‐plasmon resonance enhancing the optical non‐linearity and dynamic coupling of asymmetrical microcavity modes. An ultralow‐threshold photon intensity of 2.1 MW cm^?2 and an ultrahigh transmission contrast over 10⁴ are realized simultaneously. Compared with previously reported all‐optical diodes, the operating power is reduced by five orders of magnitude, while the transmission contrast is enlarged by three orders of magnitude.