副载波多路复用模拟光传输系统中激光器非线性畸变的分析

本文主要分析副载波多路复用模拟光传输系统中激光器的非线性畸变，提出一个激光器非线性失真分析的完整的数学模型，特别考虑了多路副载波情况下激光器的削波影响。认真分析了ＱｕｎＳｈｉ等人的论文，对他们提出的传输系统中ＣＳＯ和ＣＴＢ的计算公式进行了改进，考虑了高阶失真项的影响。理论推导已为实验所得多路光纤ＣＡＴＶ链路中的ＣＳＯ和ＣＴＢ结果所证实。     

Performance characteristics and applications of hybrid multichannelANI-VSB/M-QAM video lightwave transmission systems

The performance characteristics and applications of hybrid multichannel amplitude modulation vestigal sideband (AM-VSB)/M-quadrature amplitude modulation (QAM) video lightwave transmission systems operating at either 1310 or 1550 nm are reviewed. These systems can transport up to 80 AM-VSB video channels and more than 30 64/256-QAM digital video channels over a standard single-mode fiber (SMF) using a single laser transmitter. Five main transmission impairment mechanisms for these systems are reviewed as follows: (a) clipping-induced impulse noise, (b) bursty nonlinear distortions, (c) multiple optical reflections, (d) stimulated Brillouin scattering, and (e) self-phase modulation. For AM-QAM video lightwave trunking applications, the in-line erbium-doped fiber amplifier (EDFA) selection is discussed using a frequency-domain simulation model. Such lightwave trunking systems can provide an AM carrier-to-noise ratio (CNR) greater than 50 dB with composite second order (CSO) and composite-triple-beat (CTB) distortions less than -65 dBc, and nearly error-free transmission (BER⩽10^-9) for the 64-QAM channels with signal-to-noise ratio (SNR) of 30-dB or better. Comparison between 64-QAM and 256-QAM video channel transmission and the effect of the QAM channels on the AM-VSB channels are also presented. The implications of these results and others in hybrid multichannel AM-QAM video lightwave trunking systems are discussed     

Recent advances in theory and applications of scrambling techniquesfor lightwave transmission

This paper discusses recent advances in the theory and applications of scrambling techniques for digital lightwave transmission. It introduces the theories of sequence space and shift register generator (SRG) space which enable systematic analysis and mathematical manipulation of the behavior of sequences in general and the related SRG's. It discusses the behavior and realization of frame synchronous scrambling (FSS) and distributed sample scrambling (DSS) with emphasis on parallel sequences and the related parallel SRG's (PSRG). In addition, it describes self synchronous scrambling (SSS). Then the paper applies the theories to today's lightwave transmission systems by demonstrating practical parallel designs of FSS for SDH/SONET transmission, DSS for cell-based ATM transmission, and SSS for SDH-based ATM transmission. It finally considers how DSS can be used for scrambling of mixed isochronous and nonisochronous data in future high-speed data networks. The paper employs various new concepts and terminology, such as PSRG engine, generating vector discrimination matrix, (M,N) PSRG, sampling vector, correction vector, correction matrix, predictable scrambling concurrent sampling, and immediate correction     

Numerical simulation of clipping induced distortion in externallymodulated lightwave AM-SCM systems

For the first time to our knowledge the results of numerical simulation, and experimental verification, of clipping induced distortion in externally modulated lightwave AM-SCM CATV systems are presented. Comparison of these results with clipping induced distortion in directly modulated systems show a remarkable outcome: under the same modulation conditions the composite triple beat (CTB) distortion component in externally modulated systems is 6 dB higher than in directly modulated systems     

Compensation for Nonlinear Distortion of Optical Transmitter with Predistortion

The paper studies the nonlinear distortion of direct modulated laser diode applying to AM-VSB lightwave CATV systems from the viewpoint of rate equations and designs a predistortion circuit in an easier way. It is shown that CSO and CTB in 60 PAL channels have been improved obviously.     

High-fidelity lightwave transmission of multiple AM-VSB NTSCsignals

The progress towards developing AM lightwave links for the transmission of multiple TV signals is reported. While the signal-quality objectives and transmission distances are appropriate for CATV trunking, the technology is expected to have applicability to the distribution of video signals in the subscriber loop. Highly linear 1.3-μm distributed feedback (DFB) lasers designed expressly for analog requirements are used to transmit 42 continuous wave carriers according to the standard US CATV frequency plan. For the best lasers, when evaluated over 12 km of fiber, carrier to noise was >52 dB, composite second-order distortion was >70 dBc, and composite triple beat was >70 dBc. The relationship between measurements with continuous wave carriers and actual video signals is discussed. System design rules are offered. Properties that lead to superior analog performance are discussed. Data from 700 links indicate that composite third-order distortion generally scales with product count but that composite second-order distortion has a significant frequency-dependent component     

Single-mode lightwave transmission in SOI-type photonic-crystalline-defect waveguides with phase-shifted holes

Single-mode lightwave transmission was observed in novel line-defect photonic-crystal (PC) waveguides. The waveguide structure is constructed by adding phase-shifted holes in an ordinary missing-hole line defect. This device permits a fine single-mode lightwave transmission even though the waveguide structure is fabricated on silicon-on-insulator (SOI) substrate, which seriously promotes off-plane leakage of waveguiding modes     

A Comparison of Lightwave, Microwave, and Coaxial Transmission Technologies

The relative performance, complexity, and cost for three digital transmission technologies-microwave, coaxial, and lightwave- are compared from the point of view of the lightwave technologist. It is found that lightwave systems are inherently noisier than the others. However, its bandwidth advantage can be exploited through bandwidth expansion techniques to overcome the noise disadvantage. It is further found that lightwave systems are potentially less complex than their radio and wireline counterparts given the advancements expected in the near future. Lastly, it is found that present-day lightwave systems can be less costly than the other technologies. Furthermore, it is found that anticipated near-term improvements to the technology will make lightwave systems even more attractive from the cost point of view. It is concluded that digital lightwave and microwave systems will continue to grow in usage-each has its own unique advantages relative to the other-and that digital coaxial systems will decline in usage.     

一种考虑MOS效应及频变特性的类传输线型锥形TSV通孔电学模型

为准确描述锥形TSV通孔寄生电阻、电容、电感高频下MOS效应及其频变特性,本文首先推导出了锥形TSV通孔压控MOS电容的解析模型。其次基于修正后的双传输线寄生参数提取公式对锥形TSV通孔内寄生参数进行了提取。最终建立了一种考虑MOS效应及频变特性的类传输线型锥形TSV通孔电学模型。通过仿真工具验证模型精度,结果显示：在100GHz频带内模型与仿真结果吻合度较高,可以准确描述高频下锥形TSV通孔内寄生参数的半导体物理特性及频变特性,可用来预测锥形TSV通孔的电学特性,对优化三维集成电路电学性能有一定指导意义。     

Recent progress in amplified undersea systems

The advent of the optical amplifiers has removed the loss limitation of the fiber in the conventional undersea systems using 3R (retiming, reshaping, regenerating) repeaters, and it has introduced new design criteria for the undersea lightwave systems. The accumulation of the small impairment factors that was negligible in the conventional system becomes significant to determine the transmission performances of the amplified system. The fiber nonlinearity is a distinctive limitation factor that dominates the transmission performance of the amplified system, although it was not a limitation factor in the conventional system. This paper describes the recent progress of the undersea lightwave cable systems employing optical amplifier repeaters. The limitation factors and the polarization dependent characteristics of the amplified system are described. The system demonstrations with conventional IM-DD technology are presented using both recirculating loop and straight fiber transmission line. The system maintenance method is also explained briefly. Future technologies adopting the WDM or the optical solitons are also discussed     

A double-stage injection-locked oscillator for optically fed phasedarray antennas

In an optically fed phased array antenna system, the microwave carrier signal is transmitted via a modulated lightwave to each active T/R (transmit/receive) module, where it must be converted back to the microwave domain. Currently, efficient optical-to-microwave conversion is extremely difficult, as the detected microwave signal is weak and noisy. A novel circuit, containing a high-gain/low-noise microwave injection-locked oscillator, has been developed to improve the interface between the optical and microwave components. The circuit utilizes two FETs and a dielectric resonator, which serves as a frequency-dependent feedback element. The circuit, designed to operate at about 8 GHz, provides significant amplitude and phase noise suppression. In addition, the circuit realization is compatible with MMIC technology     

Microwave-multiplexed lightwave systems: A new approach to wideband networks

For the last fifteen years the attention of the fibre-optic community has been principally focused on developing baseband digital transmission system for transmitting time-division-multiplexed voice channels over long distance and interoffice routes. Attention has now shifted to extending the fibreoptic network to the subscriber loop and to providing a multitude of new services through lightwave networks. Based on the results reviewed here, it is apparent that microwave-multiplexing techniques provide a new and attractive way to transmit wideband services over optical fibre. By allowing lightwave systems designers to use and combine the complete range of available electronics, including both analog and digital electronics, and both baseband and microwave techniques, a great number of new possibilities arise for exploiting the bandwidth of lightwave components and for designing wideband lightwave networks. Over the next few years the microwave-multiplexing techniques described in this article may fundamentally change the way we use lightwave technology.     

1.13-Gbit/lightwave transmission system

A new high capacity lightwave transmission system has been developed using GaAs semicustom logic arrays and a DFB single-mode laser, and is presently in production. The architecture of this product is designed for in-service upgrade of a 565-Mbit/s product. This paper reviews the technical characteristics and design considerations of the Rockwell LTS-21130 lightwave transmission system.     

Mach-Zehnder interferometer exactly aligned with ITU grid frequencies

We propose a new Mach-Zehnder interferometer (MZI) that can align passband/rejection-band centers exactly with an arbitrary frequency grid. The proposed MZI incorporates phase-generating couplers, which generate a nonlinear frequency-dependent phase to control the absolute frequency and the dispersion of the waveguide refractive index simultaneously. As an example, we present an MZI that is exactly aligned with the 50-GHz spaced International Telecommunication Union grid. We fabricated the proposed MZI using silica-based planar lightwave circuit technology and demonstrated an MZI with a frequency error of less than /spl plusmn/0.3 GHz over a wide frequency range of 10 THz.     

High-speed optical transmission systems using advanced monolithicIC technologies

The authors discuss the design and performance of monolithic ICs for multigigabit lightwave transmission systems including direct detection and coherent detection. The required function and performance of a lightwave transmitter and receiver are discussed. The fabricated ICs and their application to the transmission system are shown in a direct system. Microwave monolithic ICs for lightwave heterodyne detection and an interconnection technique are introduced. Future trends of ICs are discussed     

Triggerable semiconductor lasers

A triggerable semiconductor laser emits light in very short (0.1 ns) intense (0.1 W) pulses with a few nanosecond periods when biased a fraction of a milliampere above a threshold current. Single uniform lightwave pulses can be triggered by fractional milliampere current pulses up to several nanoseconds in duration. This behavior was first seen in computer simulations of devices with a high electron-trap density (other causes are possible). Devices exhibiting this behavior have been found among the population of AlGaAs stripe lasers made by deep proton bombardment. A simple lightwave pulse regenerator has been built by adding a photodiode with less than unity gain. This circuit emits lightwave pulses with 6 pJ energy, less than 0.2 ns in duration, and with an amplitude that is up to 15 times larger than the input pulse.     

High-speed optical receiver with soft decision ISI cancellation

A receiver with soft decision intersymbol interference (ISI) cancellation (SDIC) is presented to deal with ISI in high-speed lightwave systems. The analytical and simulation results show that the transmission distance can be doubled with SDIC. In addition, the receiver with SDIC allows the ISI cancellation circuit to operate with a processing and propagation delay much longer than 1-b period. Therefore, it is very promising in very-high-bit-rate optical systems     

The impact of CSO/CTB distortion on BER characteristics by hybridmultichannel analog/QAM transmission systems

This article describes the measurements of composite second order (CSO), composite triple beats (CTB) frequency spectrum and time-varying distortion in the basic bandwidth (BB) (0-4 MHz) of the 64-QAM digital channels by multichannel AM/64-QAM optical and coaxial transmission systems. For any regular standard frequency plans (Europe, USA, NCTA, etc.) there is, for the I and Q components in the BB of the QAM channels, the harmonic series of the CSO/CTB with the first harmonic f ₁. It has been shown that for all the same laser-optics or coaxial transmission systems the CSO/CTB distortions spectrum form in the QAM BB 60-80 μs duration bursts of a series pulse with a pulse period T=1/f₁ and a pulse duration τ≈0.4/f_m, where f_m is the CSO/CTB harmonic with maximum amplitude in the QAM BB. The bursts result in the essential unevenness of error bits in time domain distribution. These bursts can deteriorate essential error correction by the interleaver-deinterleaver and Reed-Solomon (RS) forward error correction (FEC) code of the transmission systems also with a relative low bit error rate (BER) of about 10^-5 before FEC. There is, white Gaussian noise like, intermodulation distortion from interaction of digital-, digital-analog channels too, that have added white Gaussian noise     

Rockwell 135 Mbit/s lightwave system

A new intermediate-capacity digital lightwave system has been developed using digital gate array technology, hermetically sealed optical hybrids, and decision feedback equalization of the lightwave fiber. This paper reviews the technical characteristics and design considerations of the Rockwell LTS-135 lightwave transmission system.