光纤AM——CATV外调制传输系统中受激布里渊散射及其抑制

受激布里渊散射（ＳＢＳ）的抑制是光纤ＡＭ－ＣＡＴＶ外调制传输系统中的关键技术之一。本文对光纤ＡＭ－ＣＡＴＶ（调幅有线电视）外调制传输系统中ＳＢＳ的机理与ＳＢＳ阈值的特点进行了分析,并介绍了激光器高频抖动法和相位调制法两种有效的ＳＢＳ抑制技术。     

光纤AM—CATV外调制传输系统中受激布里渊散射及其抑制

受激布里渊散射（ＳＢＳ）的抑制是光纤ＡＭ－ＣＡＴＶ外调制传输系统中关键技术之一。文中对光纤ＡＭ－ＣＡＴＶ（调幅有线电视）外调制传输系统中ＳＢＳ的机理与ＳＢＳ阈值的特点进行了分析,并介绍了激光器高频抖动法和相位调制法两种有效的ＳＢＳ抑制技术。     

受激布里渊散射的多频调相抑制法

受激布里渊散射（ＳＢＳ）的抑制是光纤ＡＭ－ＣＡＴＶ外调制传输系统中关键技术之一。本文提出了一种多频率信号相位调制抑制ＳＢＳ的方法,较之传统的单频率信号相位调制法,对ＳＢＳ阈值有较大提高。     

光纤AM-CATV外调制发射机中的关键技术

介绍了光纤ＡＭ－ＣＡＴＶ外调制发射机中的关键技术,包括最佳偏置点的稳定控制技术;光学线性调制器及预失真补偿等非线性补偿技术;以及附加相位调制法与激光器高频抖动法等受激布里渊散射（ＳＢＳ）的抑制技术。     

光纤AM—CATV外调制传输系统中的关键技术

介绍了光纤ＡＭ－ＣＡＴＶ外调制传输技术中的关键技术,包括外调制器及其最佳偏置点的稳定控制技术;光学线性化调制器及预失真补偿等非线性补偿技术;以及附加相位调制法与激光器高频抖动法等受激布里渊散射（ＳＢＳ）的抑制技术。     

光纤AM—CATV外调制传输中SBS的激光抖动抑制及其对色散非线性与MPI噪声的

对光纤ＡＭ－ＣＡＴＶ外调制传输系统中激光抖动法抑制ＳＢＳ的原理,以及激光抖动法抑制ＳＢＳ时光纤ＡＭ－ＣＡＴＶ中的百线性失真与噪声进行了详细分析了计算,发现激光抖动法对系统的多径干涉（ＭＰＩ）噪声有一定的抑制作用,而且只要抖动信号的频率大于二倍的ＣＡＴＶ频带的最大频率,色散引起的非线性失真还可以忽略不计。     

光纤AM—CATV外调制发射机中的关键技术

本文介绍了光纤ＡＭ－ＣＡＴＶ外调制发射机中的关键技术,包括最佳偏置点的稳定控制技术光学线性化调制器及预失真补偿等非线性补偿技术;以及附加相位调制法与激光 高频抖动法等受激布里渊散射的抑制技术。     

高副载波复用光纤CATV系统的优化设计

高副载波复用（ＳＭＣＭ）ＡＭ－ＶＳＢ ＣＡＴＶ系统在国内正日渐引起人们的关注。本文提出了采用掺饵光纤放大器（ＥＤＦＡ）和线性化外调制器在系统中进行优化,以实现高副载波复用。并首次采用定量的无约束数值优化法,即单纯形法,对全系统中一些关键参数进行优化,从而为ＭＳＣＭ ＡＭ－ＶＳＢ ＣＡＴＶ系统的优化提供了一种有实际意义的通用方法。     

光纤CATV系统和光调制度

光纤ＣＡＴＶ系统的一个主要设备是ＡＭ光发送、接收端机。本文从分析ＡＭ光发送、接收端机的内部机理出发，说明了一个重要的内部参数－光调制度，它与光纤ＣＡＴＶ系统的性能指标ＣＮＲ（载噪比）、ＣＴＢ（组合三次差拍）、ＣＳＯ（组合二次差拍）等的关系，再从内部参数转为频道数与ＣＮＲ、ＣＴＢ、ＣＳＯ等的关系。为实际光纤ＣＡＴＶ系统设计给出了一个理论依据。本文同时出讲述了光调制度的控制方法、具体测量方法，以及ＡＭ     

AM光纤CATV系统信号传输的指标分析

本文分析ＡＭ光纤ＣＡＴＶ系统的Ｃ／Ｎ、ＣＴＢ、ＣＳＯ指标的计算及其在光链路传输中的变化情况。     

An optical modulation method to suppress stimulated Brillouin scattering and the phase noise in a remote interferometric fiber sensing system

A novel optical modulation method for stimulated Brillouin scattering (SBS) and the phase noise suppression in a remote interferometric fiber sensing system is proposed. Compared to the conventional phase modulation method to suppress SBS with only one phase modulation signal, another phase modulation signal with π shift is applied at the output end of the fiber, which converts the generated multi-frequency light to single-frequency light. Therefore the method can suppress not only SBS but also the phase noise induced by linewidth broadening owing to the first phase modulation. As a result, the method can keep the system a low phase noise level with a higher input power, which overcomes the conventional drawback of linewidth broadening. The results show a good reference to the design of remote interferometric fiber sensing systems.     

调相法抑制光纤CATV中受激布里渊散射的实验研究

对光纤AM CATV外调制传输系统中附加相位调制法抑制受激布里渊散射 (SBS)进行了详细的实验研究 ,结果显示SBS抑制效果与调相源个数及相位调制深度有关 ,与调相源频率无关 ;单个调相源可将SBS阈值提高到13dBm以上 ,而两个调相源可将系统SBS阈值提高到 18dBm以上 ;相位调制对系统的非线性特性无影响     

光纤AM-CATV外调制传输系统中双频调相抑制SBS的理论分析

受激布里渊散射 SBS 的抑制是光纤 AM- CATV外调制传输系统中关键技术之一 .理论分析了双 多 频率相位调制抑制 SBS的方法 ,较之传统的单频率相位调制法 ,双 多 频率相位调制对 SBS阈值有较大提高 ,并对双频率相位调制法中调制频率的选择进行了分析与计算 .     

Optical phase modulation in an injection locked AlGaAs semiconductor laser

Optical phase modulation by injecting coherent CW light into a directly frequency modulated semiconductor laser is reported. Phase modulation was obtained at up to 800 MHz modulation frequency without distortion for a 1.6 GHz full locking bandwidth. A static phase shift of ? took place with a 0.48 mA bias current change in the injection locked laser. Experimental and theoretical results showed that the product of the normalised phase deviation by the frequency deviation and the cutoff modulation frequency is constant.     

Phase noise in coherent analog AM-WIRNA optical links

Coherent analog amplitude modulated-wideband rectifier narrowband (AM-WIRNA) systems have been the focus of many recent studies because of their high performance and relative immunity to phase noise compared to angle modulated systems. Despite their natural advantages over angle modulated systems, AM-WIRNA receivers are still vulnerable to phase noise because of distortion of their phase broadened signals in a finite bandwidth system. We present the first numerical analysis of the effects of this distortion on the performance of AM-WIRNA systems. The analysis accurately models the power spectral density of the phase-to-intensity noise with a root-mean-square deviation from the averaged experimental noise spectrum of 1.2 dB and a maximum deviation of 3.8 dB in the modulation range of <2 GHz. The accuracy of the analysis is limited primarily by nonidealities in the AM-WIRNA receiver and the accuracy of the analytical intermediate frequency (IF) filter model. Optimal link designs are presented which minimize the impact of phase-to-distortion noise in AM-WIRNA systems. We present experimental data from AM-WIRNA links which use both external cavity and distributed feedback lasers for the signal and local oscillator sources. The numerical analysis predicts the link signal-to-noise ratio (SNR) for different signal laser powers to within 1.4 dB of experiment. We find that systems requiring high SNR such as phased array antennas and AM-CATV are significantly affected by this noise     

Degradation of modulation and noise characteristics ofsemiconductor lasers after propagation in optical fiber due to a phaseshift induced by stimulated Brillouin scattering

Here we demonstrate theoretically that stimulated Brillouin scattering (SBS) can induce a phase shift of the optical carrier relative to its sidebands due to the waveguiding effect of the optical fiber on the acoustic wave. This causes conversion of frequency modulation to intensity modulation, which results in an increase in the relative intensity noise and degradation of the modulation response of directly modulated lasers after propagation in an optical fiber, in agreement with our experimental observations. Suppression of SBS can be achieved at low frequencies and high modulation powers due to the laser adiabatic chirp     

Notes on the theory of modulation

The transmission system of "frequency modulation" (transmission by variation of the frequency of the radiated wave) is mathematically analyzed, and the width of the band of frequencies occupied by this method of transmission at a given speed is compared with the width of the corresponding band for transmission by amplitude variation. It is proved that the frequency modulation system using a spacing or compensating wave is inferior to the amplitude variation system both as to the width of the frequency band occupied and as to distortion of signal waveform.     

30-GHz millimeter-wave carrier generation with single sideband modulation based on stimulated Brillouin scattering

A new technique to generate a millimeter（mm）-wave carrier of 32.57 GHz(f_LO=10.85 GHz) with single sideband modulation（SSB） for radio-over-fiber（RoF） systems is experimentally demonstrated by using stimulated Brillouin scattering（SBS）.The SSB is realized by directly amplifying the +3rd sideband of the modulated optical carrier in the process of SBS.The pump wave is provided through a double Brillouin scattering frequency shifting configuration.The use of the same laser source to generate the pump wave ensures the stability of the mm-wave generation system since the relative frequency shift between them can be eliminated.In addition, the mm-wave carrier obtains an RF power gain of 21 dB with the SBS amplification and a 3-dB bandwidth of 10kHz.     

调制滤波引起脉冲起伏研究

由于惯性约束聚变(Inertia confinement fusion,ICF)中约束激光功率较大,常会在后续光学系统中产生受激布里渊散射(SBS).一般应用相位调制器使单纵模激光展宽,提高SBS阈值.基于计算机模拟平台进行了模拟研究,讨论经过相位及幅度调制后再通过宽带或窄带滤波器激光脉冲变化情况.结合在实验上观察到的对应于4.3 GHz调制频率的0.23 ns间隔脉冲起伏,提出滤波导致高频分量缺失是产生脉冲顶部高频起伏的根本原因,而滤波中心波长偏离激光中心波长导致在实验上观察到明显起伏.通过数值模拟给出了不同滤波波形对脉冲高频起伏的影响,并给出滤波带宽、中心波长偏差和顶部起伏大小的关系,提出减小起伏的优化方法.滤波带宽和激光中心波长存在偏差时,选择较小滤波带宽,应该优先考虑使用类高斯形的滤波器;而当滤波带宽比较大,选择类方波形滤波器较有优势.     

利用扰动抑制SBS效应的实验研究

文章从光传输系统中受激布里渊散射(SBS)效应产生的基本原理出发．分析了扰动对SBS效应抑制的理论基础。利用实验方法研究了10Gbit／s光传输系统在不同输入功率的情况下．通过叠加扰动对SBS效应的抑制效果,得到了最佳的扰动频率和扰动信号的调制幅度。