基于半导体材料微纳波导全光逻辑门的研究进展

全光逻辑门是全光计算以及全光信号处理系统中关键的光子器件.随着互补金属氧化物半导体(COMS)工艺的发展,基于半导体材料微纳波导全光逻辑门已经成为集成光学领域中的重要方向;尤其是硅基光子集成器件在近些年成为了国际研究热点.文章主要对基于绝缘体上的硅(SOD)和Ⅲ-Ⅴ族化合物材料不同波导结构(马赫-曾德尔干涉仪(Mach-Zehnder interferometer)微环谐振腔和条形波导结构)的全光逻辑门的研究进展进行了介绍,并且在器件的工作速率和功耗方面,分别对上述基于SOI和Ⅲ-Ⅴ族化合物材料三种不同波导结构的全光逻辑门进行了分析和比较.     

All-optical functions based on semiconductor ring lasers

Semiconductor ring laser （SRL） has been shown to possess robust bistability between its two possible directions, i.e., clockwise （cw） and counter-clockwise （ccw） lasing, routinely demonstrating directional extinction ratio （DER） of 〉 25 dB. In this paper, experimental schemes and results using the SRL as a universal photonic digital element to form all-optical logic, memory, and signal processing circuits are summarized. It is demonstrated that the SRL can be used for both combinatorial and sequential logic functions, and as all-optical regeneration devices. Furthermore, it is shown that a SRL logic circuit can be all-optically reconfigured to perform different all-optical logic functions.     

基于SOA的环形腔激光器在全光信号处理中的应用

半导体光放大器（SOA）因其具有良好的光光互作用特性,包括交叉增益调制、交叉相位调制、交叉偏振调制以及四波混频等,在全光信号处理技术中已经获得了广泛的应用。利用SOA与光纤反馈可构成环形腔激光器S_FRL。在S—FRL中将SOA的光一光互作用特性与反馈条件相结合,可以改变孓FRI．的起振、抑制、选频等多种状态,从而构成不同功能的全光信号处理器件。在分析S—FRL激光振荡原理的基础上,提出了双环耦合的S-FRL,并以此为基础构成一种双环耦合的双稳态触发器,进而构成一种同步脉冲展宽器;还提出了一种级联的S-FRL,由此构成一种基于负逻辑的全光判决器。     

An all-optical matrix multiplication scheme with non-linear material based switching system

Optics is a potential candidate in information, data, and image processing. In all-optical data and information processing, optics has been used as information carrying signal because of its inherent advantages of parallelism. Several optical methods are proposed in support of the above processing. In many algebraic,arithmetic, and image processing schemes fundamental logic and memory operations are conducted exploring all-optical devices. In this communication we report an all-optical matrix multiplication operation with non-linear material based switching circuit.     

Mach-Zehnder interferometer-based tree architecture for all-optical logic and arithmetic operations

Interferometric devices for optical processing have been of great interest in recent years. Semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI) has already taken a significant role in the field of ultra-fast all-optical signal processing. Optical tree architecture (OTA) provides important contributions in optical interconnecting networks. In this communication, we have tried to exploit the advantages of both OTA and SOA-based MZI switches. We have proposed SOA-MZI-based tree architecture, a new and alternative scheme, for integrated all-optical logic and arithmetic operations. This architecture can enable one to perform all-optical processing of signals, including two input logic operations, half-adder, full-adder, full-subtractor, one-bit data comparator, etc.     

Four-Wave Mixing in Microwires to All-Optical Signal Processing in Mode-Division Multiplexing Systems

Abstract

Mode-division multiplexing requires all-optical signal processing techniques that are able to deal with a new coding dimension, the spatial mode. In this context, optical microwires emerge as a potential highly non-linear and multi-modal waveguide envisioning the development of all-optical signal processing devices to mode-division multiplexing systems based on the four-wave mixing process. The inter- and intramodal phase-matching conditions for the four-wave mixing process are mapped as a function of the microwire diameter and the wavelength of signals. Moreover, the efficiency of four-wave mixing considering a strong guiding regime is investigated in the multi-modal regime.     

半导体光放大器的光-光互作用及其应用

半导体光放大器（SOA）中的非线性系数约为普通光纤的10^9，为光子晶体光纤的10^7，而且有4种光-光互作用，即交叉增益调制（XGM）、交叉相位调制（XPM）、交叉偏振调制（XSM）及四波混频（FWM），可以灵活地组成各种光信号处理器件，如波长变换器、全光触发器、全光逻辑、全光时钟恢复、全光缓存器……等，正成为整个光信号处理的基础。文章介绍了它们的原理和简单应用。     

Control of the switch between optical multistability and bistability in three-level V-type atoms

We theoretically investigated a hybrid absorptive-dispersive optical bistability and multistability behaviour in a three-level V-type system using a microwave field driving a hyperfine transition between two upper excited states inside a unidirectional ring cavity. We find that the intensity and the frequency detuning of the coupling field as well as the intensity of the microwave field can affect the OM behaviour dramatically, which can be used to control the transition from OM to OB or vice versa without need to resort the effect of the quantum interference. The effects of the phase, the quantum interference and the atomic cooperation parameter on the OM are also studied. Our scheme may be used for building more efficient all-optical switches and logic-gate devices for optical computing and quantum information processing.     

Erratum to: Multiple magnetic transitions in single crystals of Ce12Fe57.5As41and La12Fe57.5As41

Commercial computers based on electronic logic devices have brought great changes to the world. However, traditional electronic devices are suffering from numerous technical challenges in their attempts to continue to satisfy Moore's law. Alloptical logic devices, as promising successors to their electronic counterparts, have become a major focus of optics research. In this paper, we provide a review of current all-optical logic devices. The logic gates in these devices, which are described in the first part of the review, are divided into five categories based on the different principles used in their realization. Complex optical devices with various functions and reconfigurable devices are summarized in the next section. In the final part of this paper, we discuss some of the previous works on all-optical integrated chips with specific functions. This review will provide a complete technological roadmap for all-optical devices and aims to be helpful in possible future developments in this growing field.     

High-speed optical signal processing using semiconductor optical amplifiers

The authors report on all-optical switching devices based on semiconductor optical amplifiers (SOA) in applications for optical time division multiplexing (OTDM) transmission technology. The report includes a discussion on the basic properties of an SOA, on the nonlinear processes of cross-phase modulation and four-wave mixing in the SOA used for all-optical switching, and on the application of the SOA as demultiplexer, add-drop multiplexer, clock recovery and wavelength converter. The devices considered here operate at data rates in excess of \Gb80, where electrical signal processing is not available today.     

Ultrafast all-optical signal processing with Symmetric Mach–Zehnder type all-optical switches

We present Symmetric Mach–Zehnder (SMZ) type all-optical switches: an SMZ all-optical switch, a polarization-discriminating SMZ (PD-SMZ) all-optical switch, and a delayed interference signal wavelength converter (DISC). These switches are capable of ultrafast, low control power, and low chirp switching, which is not restricted by slow relaxation of highly efficient nonlinearities. High repetition operation unrestricted by slow relaxation is also possible for these switches. This is because of a push–pull modulation scheme or sometimes called a differential phase modulation scheme. These three devices are similar, but different in some important aspects, thus a comparison is made among the three. Then semiconductor optical amplifiers (SOAs) are discussed as a nonlinear phase shifter for these devices. Then, ultrafast all-optical signal processing using SOA based SMZs is demonstrated. Error-free demultiplexing from 168 to 10.5 Gbit/s is presented, in which a hybrid-integrated SMZ (HI-SMZ) is used as a demultiplexer. In pulse regeneration experiment, the signal pulses at 84 Gbit/s are regenerated by the PD-SMZ and the regenerated pulses are demultiplexed to 10.5 Gbit/s by the HI-SMZ to verify error-free operation. The retiming capability of this scheme is quantitatively demonstrated. Also presented is error-free all-optical wavelength conversion at 168 Gbit/s using the DISC. These results represent the fastest error-free operations reported to date in each category.     

Ultra-high on/off ratio optical trigger based on SOI–SOA waveguide

We present a device able to perform an all-optical trigger by utilizing the cascaded silicon-on-insulator (SOI) and semiconductor-optical-amplifier (SOA) optical waveguides, where both the controlling pulse and the signal pulse are co-propagating along the device. The results of numerical simulations show that the all-optical trigger behavior with ultra-high on/off ratio can be easily achieved by adjusting the device parameters. To improve and optimize the optical trigger operation, the negative initial delay (the signal pulse before the controlling pulse) and the positive initial delay (the signal pulse after the controlling pulse) are considered for performing the optical trigger operation.     

Realizing reliable logic and memory function with noise-assisted Schmitt trigger circuits

Schmitt trigger is a comparator circuit with hysteresis, implemented by applying positive feedback to a noninverting input. Recently, it has been verified that noise under certain condition can help nonlinear circuit to realize reliable logical stochastic resonance (LSR). In this letter, we demonstrate that, without any modifications, Schmitt trigger can operate flexibly both as logic operation and latch operation in an optimal noise range. In traditional Schmitt trigger, the hysteresis is designed for resisting noise. In the new design, the hysteresis tends to enhance the LSR effect in Schmitt trigger with the help of noise and helps the system to perform better at higher noise levels. Thus, our results extend the application scope and generality of the traditional Schmitt trigger.     

Optical signal processing using four wave mixing in highly nonlinear silicon nano-wire

Silicon-on-insulator (SOI) waveguide devices are emerging for the realization of optical signal processing systems for the last couple of years. The recent technological advancement in silicon photonics is the main driving force at the back of these devices. Using non-linear optical phenomenon in silicon wires and their compatibility with CMOS devices provide the stage for integrated photonic devices. All-optical signal processing devices are being investigated at present, but the chip-scale solution provided by the silicon photonics is the most promising. In this research we have investigated all-optical signal processing in a 10 mm long SOI waveguide by exploiting well established coupled wave equations. We consider single pulsed pump to analyze frequency shifting by four-wave-mixing (FWM). For the wavelengths 20?30 nm far from the pump, the gain overcomes nonlinear losses resulting in higher frequency conversion efficiency.     

光梯度力驱动的纳米硅基光开关

通过一道光改变另一道光的传输路线是光子集成网络中重要而长远的目标, 然而, 由于硅材料的光学非线性较弱, 在硅材料上实现开关的全光控制难以实现. 因此本文提出了一种由光梯度力驱动的纳米硅基光开关, 实现了硅基光开关的全光控制. 该光开关由一个部分悬空的微环谐振器和一个交叉波导结构构成, 当通入一道控制光时, 悬空的微环谐振器在光梯度力的作用下发生弯曲, 微环谐振器的谐振波长随之发生变化, 从而实现光信号的传输路线发生改变. 该光开关利用纳米光子制造技术在标准绝缘体上硅晶圆上制造, 实验数据得出其最小消光比为10.67 dB, 最大串扰为 -11.01 dB, 开关时间分别为180 ns和170 ns. 该光开关具有尺寸小, 响应速度快, 低损耗和可拓展等优点, 在片上集成光路、高速信号处理以及下一代光纤通信网络中具有潜在应用.     

全光地址识别机理的研究

在面向分组业务的全光交换系统中,采用全光地址处理技术可以减少处理时延,大大提高信息处理速度和网络吞吐量,对全光网络的研究具有重要意义。分析了光正交码的自相关性与互相关性,并将其特性应用于全光传送网中,以针对未来基于光分组业务的全光环网为例,提出了一种光分插复用器的新型结构,给出了总体应用设计规则,重点研究和分析了全光地址识别机理和相关的应用设计方法,给出了针对全光环网组网规模的仿真分析结构和基本实验结果。结果表明采用所提出的设计原则和设计方法来实现全光地址识别是可行的。     

非线性克尔效应对飞秒激光偏振的超快调制

研究了近红外飞秒激光的偏振在太赫兹频率的超快调制.利用抽运-探测光谱技术,通过改变两个脉冲之间的延迟时间可以控制光脉冲的旋转角.在Li：NaTb（WO₄）₂磁光晶体中观察到探测光的偏振随延迟时间变化的高速振荡,振荡信号的中心频率为0.19 THz.这种超快偏振调制现象可以解释为,抽运-探测实验构置中,前向传播的抽运光诱导的光学克尔非线性引起被晶体远端表面所反射的背向传播的探测光脉冲偏振面的额外旋转.通过改变抽运光的圆偏振旋性可以控制探测光调制信号的相位和振幅.实验结果表明,非线性光学克尔效应可以作为一种全新的手段,在磁光晶体中实现近红外飞秒激光以太赫兹频率的超快偏振调控.这将在超快磁光调制器等全光器件中得以应用.实验结果将有助于偏振依赖的超快动力学过程的研究.     

Nonlinear Phase Shift by Parametric Amplification in Leaky Waveguides

In this article, the cascaded second-order nonlinear phase shifts induced in the signal wave are studied using the three-wave parametric interaction in a four-layered QPM leaky waveguide configuration in Z-cut LiNbO 3 . In this interaction, the pump-andsignal waves are guided modes and the idler is radiated into the substrate. We have analyzed the nonlinear phase shifts induced in the signal wave due to cascaded second-order effects, as a function of different waveguide parameters. These studies should find application in realizing practical all-optical signal processing devices.     

Nonlinear Phase Shift by Parametric Amplification in Leaky Waveguides

In this article, the cascaded second-order nonlinear phase shifts induced in the signal wave are studied using the three-wave parametric interaction in a four-layered QPM leaky waveguide configuration in Z-cut LiNbO 3 . In this interaction, the pump-andsignal waves are guided modes and the idler is radiated into the substrate. We have analyzed the nonlinear phase shifts induced in the signal wave due to cascaded second-order effects, as a function of different waveguide parameters. These studies should find application in realizing practical all-optical signal processing devices.     

A method of generating single optical pulse in nanosecond range with the joint uses of electro-optic modulator and nonlinear material

Optics has already been established as a successful candidate in data processing. Lots of all-optical data processors are proposed in the last few decades. Again it is well-known that, in many situations, an optical single pulse is very much useful to trigger an optical data processing circuit. In this communication the authors propose a method of generating a sub-nanosecond optical pulse using electro-optic modulator and nonlinear material.