全光半加器的研究进展

综述了全光半加器的研究进展和现状.阐述了不同结构全光半加器的工作原理、优缺点,并展望了全光半加器未来的发展方向.

Abstract：

It is summarized for current all-optical half-adder.The principles of different kinds of all-optical half-adders are analyzed,and their advantages and disadvantages are also discussed.Finally,the prospects of all-optical half-adder are given.     

8 × 10 Gb/s transmission system over 2 015 km with dispersion compensation by fiber Bragg Grating

The cascaded chirp fiber Bragg gratings（CFBGs） with ITU-T standard wavelengths and wavelength grid are applied to compensate the dispersion of 8×10 Gb/s WDM system. The ASE of the EDFA could be reduced, the OSNR of the transmitted signal can be increased and the fluctuation of the EDFA gain can be restrained in a certain scope by the CFBG employed in the system. Experiment of error-free 8×10 Gb/s 2015 km transmission without FEC and electric regeneration is demonstrated in this paper. In this system, only EDFA is used as amplifier,and no other form of dispersion compensator is adopted except CFBG. The experimental result showed that after 2 015 km transmission,the consistency of the dispersion compensating for each channel is perfect.     

Real-time wavelength routing based on Bragg reflection with integrated forward Raman for long-reach networks

We experimentally demonstrate the all-optical efficient technique for dynamic full-duplex wavelength routing and reach extension through adoption of passive fibre Bragg grating(FBG),energy efficient vertical cavity surface emitting lasers(VCSELs)and high gain forward Raman pump.In this study,two VCSEL channels at 1549.62 nm and 1550.01 nm are directly modulated with a 8.5 Gbit/s data signal each,and transmitted over 25.5 km fibre to a passive single mode FBG-based wavelength routing node.The precise wavelength selectivity of the FBG is exploited to achieve all-optical real-time wavelength routing of the 1549.62 nm VCSEL channel with a maximum insertion loss of 22.1 dB.The 1550.01 nm channel is transmitted through the FBG with a maximum penalty of 1.03 dB.By utilizing the 7.2 dB flat gain of a forward Raman pump,the routed 1549.62 nm VCSEL channel is transmitted over 76.7 km fibre with a maximum penalty of 3.84 dB at bit error rate(BER)of 5-5.Our technique is all-optical,power efficient as it employs passive FBG and circulators and has low cross talk allied to precise wavelength selectivity of the technique.     

A special issue on photonic signal processing

Photonic signal processing has been receiving increasing attention for about fifteen years.It would be enabling technology for next generation large capacity optical networks because it can avoid electronics bottleneck and decrease power consumption greatly.There are two main areas related to photonic signal processing.One topic is all-optical signal processing for digital bit sequence in optical network,such as all-optical wavelength conversion,alloptical logic operation,all-optical 3R regeneration,all-optical clock recovery,all-optical buffer,etc.The other topic is microwave photonic signal processing,such as microwave photonic filters,arbitrary waveform generation,RF signal generation,UWB signal generation,etc.However,there are still many problems to be solved before these functions could be used in optical networks.Researchers all over the world are concentrating on realizing photonic signal processing functions with some characteristics such as high operation speed and large bandwidth,flexible and multifunctional,potential integration.     

Wavelength Routing Algorithm of All Optical Network Based on Traffic Engineering

General multi-protocol label switching （GMPLS） based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.     

A low power high gain gain-controlled LNAC＋mixer for GNSS receivers

A low power high gain gain-controlled LNAC+mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load.Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNACmixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNAC+mixer, a previous low power LNAC+mixer, and the proposed LNAC+mixer are presented. The circuit is implemented in 0.18 m mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2and consumes 2 mA current under 1.8 V supply.     

Low power high gain gain-controlled LNA and mixer for GNSS receivers Wei Binbin(魏斌斌)1, Jiang Jinguang(江金光)1,2,3*

A low power high gain gain-controlled LNA ＋ mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNA ＋ mixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNA ＋ mixer, a previous low power LNA ＋ mixer, and the proposed LNA ＋ mixer are presented. The circuit is implemented in 0.18 #m mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2 and consumes 2 mA current under 1.8 V supply.     

EFFECTS OF ANTENNA APERTURE PHASE DISTRIBUTION ON THE SYNTHETIC ARRAY PATTERN AND THE DOPPLER-DELAY RESPONSE

The ideal aperture current distribution of SAR antenna is discussed in theoretical sense.Onthe basis of the results derived by R.C.Heimiller and R.W.Bayma,the effects of current distributionwhich is out of phase on the synthetic array pattern and the Doppler-delay response are furtheranalysed and numerical results calculated for the case of quadratic and cubic phase distributions aregiven.These results show that such phase distributions will cause a drop in gain of the syntheticarray and in signal to ambiguity ratio of the Doppler-delay response.In consideration of these effects,the author proposes his additional remarks on the range of repetition frequency given by R.W.Bayma(1975).     

120 GHz on-chip multi-mode wideband dielectric resonator antennas for THz applications

This work discusses the design methods of 120 GHz on-chip dual-mode and three-mode dielectric resonator antennas (DRAs) based on a standard CMOS technology. The bandwidths of the DRAs are expanded by merging adjacent modes with similar radiation patterns. The impedance bandwidth of 18.6% with the peak gain of 6 dBi is achieved for the proposed on-chip dual-mode DRA. In addition, the impedance bandwidth of 20.1% with the peak gain of 6.9 dBi is achieved for the proposed three-mode DRA. To the best of authors’ knowledge, the on-chip multi-mode DRAs are first proposed. The impedance bandwidth of the proposed three-mode on-chip DRA is wider than the other on-chip DRAs using planar feeding with on-chip ground. The proposed antennas are promising for terahertz applications due to the merits of wide band, high gain and high radiation efficiency.     

Modulation instability in negative refractive materials with saturable nonlinearity

Starting directly from the nonlinear propagation equation including saturable nonlinearity, the first-and the second-order nonlinear dispersions, the dispersion relation, instable condition, gain spectra, and the dimensionless cut-off frequency and gain spectra of modulation instability (MI) in the negative refractive material are deduced by adopting the linear stability analysis and Drude electromagnetic model. And the variations of the dimensionless gain spectra with the normalized angular frequency and normalized incident power are calculated and discussed for different sign relations between the linear dispersion and the third-order nonlinear coefficients. The results show that in the negative refractive index region, MI can occur irrespective of the sign relation between the linear dispersion and the third-order nonlinear coefficients. And depending on different dimensionless angular frequencies and different sign relations, the variations of the dimensionless gain spectra with incident power take on several different forms. Namely, the peak gain and the cut-off frequency of MI may increase then decrease with the increase of the incident power, or decrease monotonously. Moreover, MI may even have a threshold incident power for some cases.     

高性能光纤参量放大器的设计与应用

近年来,光纤参量放大的发展非常迅猛。分析了提高光纤参量放大增益、扩展带宽、降低偏振灵敏度的几种重要方法,并就光纤参量在分立式集中放大、透明的波长转换、归零脉码生成、OTDM开关、全光抽样、可擦除全光缓存、3R再生等方面的典型应用进行了全面综述。光纤OPA在DWDM系统、全光网等领域将有非常广泛而重要的运用。     

全光3R再生中的光判决技术

全面论述了光3R再生中各种光判决技术,包括基于光纤非线性效应的非线性光纤环镜(NOLM)技术,太赫兹光学非对称解复用(TOAD)技术,基于半导体光放大器(SOA)的马赫-曾德干涉仪(MZI)/迈克尔逊干涉仪(MI)技术和超快非线性干涉仪（UNI）,以及电吸收调制器(EAM)技术等。指出MZI/MI技术和EAM技术具有较好的发展应用前景。     

非线性光环镜在光通信系统中的新应用

非线性光环镜(NOLM)以其独特的优点,被广泛应用于光通信系统中.文章阐述了非线性光环镜的基本原理,主要介绍了应用NOLM作为光判决单元、多波长可调谐掺铒光纤激光器的增益均衡器以及2R中继器等在高速光通信系统中的新应用,分别分析了它们特点和发展状况.     

光纤参量放大的最新进展

分析了提高光纤参量放大增益、扩展带宽、降低偏振灵敏度的几种重要方法，全面综述了光纤参量在分立式集中放大、透明的波长转换、归零脉码生成、O—TDM开关、全光抽样、可擦除全光缓存、3R再生等方面的典型应用。     

光网络中的全光再生

在超高速大容量光网络中,全光3R再生（再定时、再整形、再放大）是非常必要的。光判决门是全光3R再生中非常重要的部分,其开关特性是影响全光3R再生的重要因素。在阐述了光判决门的研究现状的基础上,重点评价了以非线性光开关为基础的光判决门的开关特性及其串话、消光比、抖动容限等,以对全光3R再生的研究和优化设计提供依据。     

A Fiber-Based All-Optical 3R Regenerator for DPSK Signals

Analysis of an all-optical 3R regenerator for differential phase-shift keying (DPSK) signals is presented. Incoming DPSK signals impaired by noise are first demodulated to on-off keying (OOK) signals by a delay interferometer. The amplitude of the OOK signals is then stabilized by a fiber-based all-optical 2R regenerator. In a subsequent nonlinear fiber, locally generated optical clock pulses are phase-modulated by the stabilized OOK pulses and are output as regenerated signals. It is shown that significant phase-noise suppression is achieved by strong amplitude regeneration     

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application     

Shared OTDM packet compressor and decompressor

A novel shared packet compressor and decompressor system for OTDM is proposed. The system can process multiple packets simultaneously, promoting high utilisation of optical components. Its operation is based on bit reordering, which allows an elegant implementation. Depending on implementation all-optical 2R or 3R regeneration can be provided     

Jitter and Amplitude Noise Accumulations in Cascaded All-Optical Regenerators

This paper proposes and demonstrates a simulation model to systematically investigate jitter accumulations in cascaded all-optical 2R regenerators. The simulation results indicate that when the pattern dependence from the memory effect is minimized, the jitter accumulation depends critically on the degree of the regenerative nonlinearity. Studies of tradeoffs between the jitter from bandwidth limitation and the signal-to-noise-ratio degradation help identify the optimized regenerator bandwidth for various degrees of regenerative nonlinearity. The simulation then considers the pattern dependence from the memory effect and finds that it can severely degrade the cascadability of an optical 2R regenerator and can make it worse than that of a linear optical amplifier (optical 1R). The simulation results show good matches to the experimental results of an optical 2R regenerator based on a semiconductor optical amplifier based Mach-Zehnder interferometer. To overcome the jitter accumulation associated with the optical 2R regeneration, we experimentally demonstrate an optical 3R regenerator for optical nonreturn-to-zero signals with all-optical clock recovery. The experiments achieve more than 1000-hop cascadability for pseudorandom binary sequence 2³¹-1 inputs with a 100-km recirculation loop using lab fiber. Field trial experiments then demonstrate a more than 1000-hop cascadability for a 3R spacing of 66 km and a 100-hop cascadability for a 3R spacing of 264 km.