Optical Noise Tolerance in a Polarization-, Wavelength-, and Filter-Free All-Optical Clock Recovery System Based on a Monolithic Mode-Locked Laser

We experimentally investigated optical noise tolerance of a polarization-, wavelength-, and filter-free all-optical clock recovery system based on a monolithic mode-locked laser diode. The results showed that for input signal degradation, the jitter of the recovered clock did not degrade to approximately 8 dB/nm of the optical SNR. We also compared the clock recovery performance as functions of the wavelength and the modulation format (on-off keying and phase-shift keying) of the input data signals. We revealed that no significant changes were measured in the clock recovery performance despite such changes in the parameters of the input data signals, indicating that noise-tolerable clock recovery is expected, retaining the polarization- and the filter-free operations, regardless of the wavelength and the modulation format of the input data signals, by using our new scheme.     

Cascadability of an All-Optical 3R Regenerator Utilizing Nonlinear Phase Modulation and Offset Filtering at 10 and 40 Gb/s

The cascadability of a polarization-insensitive wavelength-preserving all-optical 3R regenerator is experimentally investigated for bit rates of 10 and 40 Gb/s. The regenerator consists of a self-pulsating laser for clock recovery, cross-phase-modulation-based retiming, and self-phase-modulation-based reshaping. A recirculating loop is used to demonstrate the cascadability of the regeneration scheme by transmitting return-to-zero on–off-keyed signals over 18 000 km at 10 Gb/s and over 8000 km at 40 Gb/s.      

1.3-$mu$m Amplifier-Free All-Optical 2R Regenerator Using Two-Mode Injection-Locked Distributed Feedback Laser Diode

This study presents a novel and cost-effective 1.3-mum all-optical 2R regenerator based on a two-mode injection-locked distributed feedback laser diode. The proposed 2R regenerator, with 14.13-dB small signal gain, has achieved an amplifier-free 10-Gb/s straight line transmission over 60 km while keeping the power penalty less than 0.84 dB at bit-error rate (BER) =10^-9. In addition, properties like BER degradation, output extinction ratio, gain, and data-rate transparency are also experimentally investigated     

Random Timing Noise Growth in a Cascaded Digital Regenerator Chain

A restriction on the type of phase-locked loop usable as a timing filter in digital regenerative repeaters is discussed. The limitation arises from the growth of random timing noise. It is shown that the use of second-order loops enables an improvement of less than 1 dB in noise bandwidth over the comparable first-order loop.     

Impact of the Signal and Nonlinearity Extinction Ratios on the Design of Nonideal 2R All-Optical Regenerators

The impact of the signal and nonlinearity extinction ratios on the optimum parameters of a reamplification and reshaping (2R) all-optical regenerator is investigated for different nonlinearity characteristic shapes. The bit error ratio (BER) is numerically evaluated along the 2R all-optical regenerator chain using the rigorous distribution and the Gaussian distribution for the optical power. It is shown that, when the extinction ratio of the signal at the transmitter output decreases, the optimum nonlinearity threshold increases. The results also show that, independent of the nonlinearity characteristic shape, the requirements on the extinction ratio of the nonlinearity can be strongly relaxed when the extinction ratio of the nonlinearity is higher than the extinction ratio of the signal at the transmitter output. Numerical results show that, only for nonlinearities with a small degree of nonlinearity and small extinction ratio, the Gaussian distribution correctly estimates the optimum regenerator parameters. For a small extinction ratio of the nonlinearity or a small extinction ratio of the signal at the transmitter output, the Gaussian distribution only provides correct estimates of the minimum BER along the regeneration chain. Furthermore, for high and moderate extinction ratios and degrees of nonlinearity, and for high and moderate extinction ratios of the signal at the transmitter output, the Gaussian distribution fails to correctly estimate the optimum regenerator parameters and minimum BER.     

Cascaded Operation of a 2R Burst-Mode Regenerator for Optical Burst Switching Network Transmission

We demonstrate the cascaded operation of an all-optical 2R burst-mode regenerator consisting of a single Mach-Zehnder interferometer, using a loop configuration that introduces a 6-dB power variation on each recirculation of the data. The device is shown to regenerate error-free 10-Gb/s data streams for up to six successive loop recirculations.     

Two-Stage SPM-Based All-Optical 2R Regeneration by Bidirectional Use of a Highly Nonlinear Fiber

Two-stage all-optical 2R (reamplification and reshaping) signal regeneration based on spectrum broadening due to self-phase modulation in a nonlinear fiber and subsequent off-centered filtering is demonstrated by the use of only one fiber spool in which the signal is transmitted twice in opposite directions. The two-stage configuration allows wavelength shift-free operation of the regenerator. Recirculating-loop signal transmission and regeneration experiment shows that the bidirectional 2R regenerator extends transmission distance by a factor more than two for an unequally-spaced 40 Gb/s short-pulse train with minimum pulse separation of 12.5 ps. Numerical simulation for assessing the influence of Rayleigh backscattering in the bidirectional configuration is performed, which shows that although some influence of Rayleigh backscattering can appear at higher operation speeds such as 80 Gb/s, strong noise reduction is still achievable by the bidirectional two-stage regeneration.      

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.     

基于电吸收调制器的40Gb/s光学3R再生器模型设计及性能分析

提出了一种结构简单而且性能稳定的40Gb/s光学3R再生器,它由基于电吸收调制的两个波长转换器与基于行波电吸收调制器的光时钟恢复器构成。     

基于嵌入式技术的分布式声振检测系统设计

设计并实现了基于嵌入式系统和GPRS无线数据网络的分布式噪声与振动检测系统,描述了系统体系结构、硬件框图和软件系统架构。该系统利用ARM处理器S3C2410作为核心处理器,依靠DSP协处理器中的软件算法实现声振信号的声级计算、频谱分析和噪声统计分析,在单个设备上集成了多种声振分析功能。同时,GPRS模块为系统提供了分布式声振检测能力,可以在一个监控中心就完成整个城市或区域的声振监控和研究工作。     

Investigation of a Rate-Selectable All-Optical Packet Clock Recovery System

This letter presents the experimental performance of a rate-selectable all-optical packet clock extractor using a Fabry-Perot (F-P) filter, a semiconductor optical amplifier (SOA), and polarization interferometers (PIs). The F-P filter with a low finesse and a free-spectral range (FSR) equal to the lowest packet data rate was used to directly extract the packet clock from the packet data stream, which ensures that the clock locks fast and vanishes quickly. Different PIs, in conjunction with the F-P filter, were used to form comb filters with different FSRs in order to suppress the undesired subharmonic frequencies. The clock then goes into SOA to reduce the low-frequency amplitude noise. We demonstrate packet clock extraction at 10, 20, and 40 Gb/s with the combination filter.     

中央空调系统空气噪声治理方法探讨

以某办公楼中央空调空气噪声超标为例,分析了产生的原因,提出了噪声综合治理的措施.     

Design and Operation of a Monolithically Integrated Two-Stage Tunable All-Optical Wavelength Converter

We report on the design and testing of a novel two-stage wavelength-converter architecture, monolithically fabricated in indium phosphide. Two widely tunable integrated sampled-grating distributed Bragg reflector lasers are utilized on chip as probes in both converter stages. The architecture provides a first-stage tunable signal that is internal to the chip (lambda_internal), facilitating cascaded integration of wavelength-sensitive structures, or allowing wavelength conversion for cases where the input wavelength is equal to the output wavelength (lambda_input = lambda_output). Output wavelength tuning over 35 nm is shown, and error-free wavelength conversion for lambda_input = lambda_output is demonstrated for four wavelengths over a 20-nm range at 2.5 Gb/s. Dynamic range measurements show less than 2 dB of power penalty over a 15-dB variation in input power.     

单片低噪声放大器的设计及其在数字T/R组件中的应用

采用GaAs PHEMT工艺，研制了单片宽带低噪声放大器。着重探讨了单片低噪声放大器在相控阵雷达数字T／R组件中应用的特殊要求，电路的工作原理与设计方法，以及ADS软件的仿真和优化；给出了主要技术指标和测试结果。最后，介绍了单片低噪声放大器在数字T／R组件中的应用。     

Design and Analysis of a Multicasting and Fault-Tolerant Optical Crossconnect for All-Optical Networks

This paper proposes an optical crossconnect (MFOXC) architecture that supports multicasting and fault tolerance. First, a tap-based and two splitter-based MFOXC node architectures are presented for wavelength routed all-optical networks. Compared to the existing optical crossconnects, the proposed MFOXC node not only performs multicasting efficiently but also improves reliability significantly. The MFOXC introduces a new feature (fault tolerance) and keeps the multicasting capability. It can be used at some critical points in a network to improve the overall reliability and multicast performance. Furthermore, the probability of maintaining fault free operations has been investigated for both MFOXC architectures. We present our evaluation results with a commonly used reliability measure, the mean time between failures (MTBF). Finally, we have proposed the cost and the sensitivity analysis for these MFOXC structures. The cost model and the sensitivity analysis show that the cost reduction in different components has various different impacts on the total cost of a MFOXC architecture. It can help us to know which component dominates the total cost and how to make a decision to choose among different MFOXC structures. The simulation results show that (1) the decrease of 75% in the cost of the N×N switch will result in the reduction of 20% in the total cost of the tap-based MFOXC, (2) the 1×2 switch has a big impact on the cost of the splitter-based MFOXC structures, and (3) the variation in the cost of the splitter does not introduce significant disadvantage to the type II splitter-based MFOXC structure.     

密钥管理系统的入侵容忍设计

本文概要介绍了入侵容忍技术的特点、原理、应用现状和发展趋势,并具体分析了如何采用入侵容忍技术实现高生存强度的密钥管理系统。     

一种低相位噪声2N分频器的设计

介绍了一种低相位噪声2N分频器的设计。该电路采用0.35μm BiCMOS SiGe工艺制作。1 kHz频偏下的相位噪声为-150 dBc/Hz,大大低于传统的分频器;在-55~125℃温度范围内,电路的工作频带为20 MHz~2.4 GHz,功耗电流约40 mA。数据输入端S0、S1、S2控制电路的分频比在21~28间变化,数据输入端与TTL/CMOS电平兼容。     

Wavelength-Shift-Free 3R Regenerator for 40-Gb/s RZ System by Optical Parametric Amplification in Fiber

We demonstrate wavelength-shift-free 3R-regenerator for 40-Gb/s optical return-to-zero (RZ) system by optical parametric amplification (OPA) with a clock-modulated pump in highly nonlinear fiber. The power penalty is improved by 2.6 dB, and the signal power is amplified by 7 dB     

一种水下有源噪声抵消系统的设计

潜艇的自噪声是影响潜艇被动声纳系统性能的重要因素。对接收信号中的潜艇自噪声进行有源抵消,从而可提高被动声纳的作用距离。该文设计了一个针对舰艇艏端被动声纳平台的本艇自噪声有源抵消系统,并设计了其试验系统方案。采用直接-并联型结构的多通道有源陷波器和滤波最小均方误差算法(FXLMS)自适应滤波算法,有效地抑制了潜艇自噪声中的线谱分量,提高了接收端的输入信噪比,提高了被动声纳作用距离。