单模光纤WDM传输中受激拉曼散射引起的串扰分析

文章通过微分方程的解,定量描述了单模光纤ＷＤＭ传输中ＳＲＳ串扰,并指出减小这种串扰的方法。     

光纤陀螺姿态系统的旋转矢量算法研究

将光纤陀螺作为一种角速率传感器,会使其姿态系统的旋转矢量算法的误差增大,角增量的提取方法改变。为此给出三子样和四子样算法的角速度提取角增量公式,推导算法在圆锥运动下的误差,根据圆锥运动下误差最小的原则,对算法系数进行改进,提出两种改进算法,推导误差公式表明改进算法比原算法的精度提高（Ωh）^2倍。仿真表明：改进算法比原算法的精度提高了半个数量级。     

Phase error bounds of fiber gyro with polarization-holding fiber

Phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber. The phase error and resulting zero-point drift is related to the polarization-holding parameterhof the fiber. Comparison of the theory with recent experimentally observed bias drift is made.     

50-dB nonlinear crosstalk suppression in a WDM analog fiber system by complementary modulation and balanced detection

We investigate, theoretically and experimentally, a novel scheme to suppress the nonlinear crosstalk between wavelengths in wavelength-division multiplexing (WDM) analog fiber systems. It is based on an improvement to a previously introduced crosstalk-suppression technique by complementary modulation of two closely spaced optical twin carriers (TCs). By combining the modulated TCs by a balanced detector (TCs-balanced detection [TC-BD]), the suppression can be improved further. We have obtained up to 50-dB crosstalk reduction at low modulation frequencies, where crosstalk is most severe, and in the most interesting region for cable television systems.     

集成光学调制器在光纤陀螺中的调制特性研究

对高精度光纤陀螺(零漂>0.01(°)/h)中的核心光学器件——铌酸锂集成光学调制器在光纤陀螺中的调制特性及系统测试方法进行了探讨,对其应用及与光路其他各部分配合的技术进行了理论分析和实验研究。与此同时,对该器件在光纤陀螺系统中的特性研究建立了通用的测试系统。文中提出了集成光学调制器与系统匹配的问题。研究结果表明:铌酸锂集成光学调制器的光、电特性以及其电特性与系统的匹配对陀螺的性能发挥着至关重要的作用。     

光纤陀螺中的关键技术分析

光纤陀螺作为一种新型的陀螺,正逐渐成为捷联惯导系统中最重要的传感器件.简要论述了光纤陀螺的基本原理和工作过程,并对光纤熔接技术、光纤绕制技术、误差检测和补偿技术、系统动态误差补偿技术、光源以及噪声抑制技术、集成光学芯片技术、数字信号处理电路等关键技术作了详细分析.     

光源谱宽对保偏光纤串音测试的影响分析

从光源相干性出发,分析了光源谱宽对保偏光纤交叉模式中耦合光波之间干涉的影响,指出了保偏光纤串音测试系统中光源谱宽越宽,串音测试结果的稳定性越好.试验结果表明,当测试系统光源谱宽为5nm时,串音跳动为1dB左右,基本可以满足一般测试要求;采用宽带光源,串音测试结果有更好的稳定性.     

Liquid pressure sensing system based on distributed polarization crosstalk analysis in polarization maintaining fiber

A novel quasi-distributed liquid pressure sensing system based on distributed polarization crosstalk analysis (DPXA) in polarization maintaining fiber (PMF) is proposed and demonstrated. We design a special structure of liquid pressure sensing units and invent a corresponding nonlinear calibration method. Five sensing units deployed on a sensing tape can effectively transform the liquid pressure into the transverse-force applied on the sensing PMF, and the induced polarization crosstalk can be measured and located by the DPXA system, so as to further establish the relationship between liquid pressure and crosstalk through the nonlinear calibration method. The liquid pressure sensing system has good sensitivity and high repeatability, and a maximal measurement relative error of 8.96% is measured for the five sensing units, which can be much improved by optimizing the packaging of sensing units. We believe our sensing system will find great applications in the field of engineering liquid pressure sensing.     

The influence of Er-doped fiber source under irradiation on fiber optic gyro

The relationship between the parameters of Er-doped fiber source (EDFS) and the performance of fiber optic gyro (FOG) is analyzed in theory firstly. Then, the irradiation resistance characterizations of FOG using EDFS with and without spectrum trimming are compared. Through the theory analysis and experimental research, it is confirmed that the mean wavelength of the EDFS with spectrum trimming varies less than the EDFS without spectrum trimming under irradiation, and the FOG used EDFS with spectrum trimming have more stable performance under irradiation. Therefore, to trim EDFS’s spectrum into a Gaussian-like spectrum is an effective manner to suppress the irradiation influence on FOG.     

Bias of a resonator fiber optic gyro composed of apolarization-maintaining fiber ring resonator with the photoinducedbirefringent grating

A theoretical study of the polarization-fluctuation induced bias of an resonator fiber optic gyro (R-FOG), which employs a polarization-maintaining fiber ring resonator with a photoinduced birefringent grating, is presented. The polarization conversion due to the photoinduced birefringent grating can stabilize the resonator output, which result in the reduction of the bias in the R-FOG output. The influences of the parameters, such as the fluctuation of the input polarization, the resonator finesse, and the photoinduced index change of the dielectric tensor, on the bias in the gyro-output have been investigated. Our results show that with the help of a photoinduced birefringent grating the bias in the gyro-output can be limited around 10^-7 rad/s (0.02 deg/hr), a typical specification for the aircraft-navigation     

Analysis and observation of coupling ratio dependence of Rayleighbackscattering noise in a fiber optic gyroscope

Noise due to Rayleigh backscattering in a fiber-optic gyroscope is observed in quadrature with the Sagnac signal. This noise can be nulled by adjustment of the coupling ratio of the loop coupler and the state of polarization in the gyro loop. A rigorous analysis of the phases of, and the modulations applied to, the primary and scattered beams shows that no coherent Rayleigh backscatter noise should be detected on the Sagnac signal even with relatively coherent semiconductor laser sources     

Analysis of signal voltage in a semiconductor ring laser gyro

It is expected that a semiconductor ring laser is useful as a gyro because of its tiny size. Here, we propose to use as signals voltage changes in a semiconductor ring laser corresponding to rotation. These changes in the voltage during rotation are caused by an interference of clockwise and counterclockwise laser beams inside the ring cavity. In this paper, these signal voltages are analyzed for the first time by using rate equations, It is shown that the signal voltages saturate with an increase in the injection current into a semiconductor ring laser if gain saturation is neglected. When gain saturation is considered, there exists an optimum injection current to obtain a signal voltage as large as possible. To confirm validity of this analysis, a signal voltage below laser threshold is compared with that of a semiconductor optical amplifier, and good agreement is obtained     

模拟环路实现谐振式光纤陀螺的频率锁定

在分析R-FOG工作原理的基础上,采用T型反馈网络作为运放的反馈回路,构建了PI控制器,以减小运放误差对PI输出的影响,将其应用到R-FOG闭环环路中,控制激光器的输出光波频率,实现了R-FOG谐振频率的长时间(4000s)的锁定,锁定稳定度优于9×10-12,10s积分时间输出下的频率锁定精度为0.24°/s。     

Statistical analysis on stimulated Raman crosstalk in dispersion-managed fiber links

Power impairments due to stimulated Raman scattering (SRS) in dispersion-managed (DM) fiber links are evaluated theoretically. We extend previous work on the statistical analysis of SRS crosstalk to the case of multiple fiber segments. Closed-form formulas are derived, and the applicable range is presented by comparison with simulation results. The SRS crosstalk in DM fiber links is evaluated using derived formulas, and the preferable configuration of DM fiber links for suppressing SRS crosstalk is discussed. We also evaluate the exact power penalty induced by the SRS crosstalk in consideration of the log-normal waveform distribution due to SRS and non-Gaussian noise and clarify the system bounds in some typical DM fiber links. The developed approach provides a design rule for DM fiber links from the viewpoint of SRS crosstalk suppression.     

Analysis of interchannel crosstalk in a dispersion-managed analog transmission link

A technique for computing the effect of cross-phase modulation (XPM) on two copropagating analog channels in an optical fiber link is presented. In this approach, the interaction between the two channels is linearized by keeping the self-phase modulation (SPM) and XPM interactions in the strong optical carrier components only at lowest order and then at the next order, deriving the effect on the modulation components of both channels when the optical carrier is strong relative to the other components of the channel. In contrast to some previously suggested approaches, it is not assumed that the pump is undistorted, and therefore, this method accurately describes distortions due to SPM, XPM, and dispersion management in both channels. This method is easily applied to systems with multiple spans employing dispersion management with loss and gain. The expressions for the received radio frequency power and crosstalk between the two channels when direct detection is used are then provided. Using this approach, new expressions for the amplitude modulation and phase modulation modes of the two channels are derived, and the way they exchange energy when SPM, XPM, and dispersion are all considered is explained. This method yields excellent agreement between theory and experimental data.     

系统中陀螺信号的三种滤波方法

在凝视扫描系统中,大惯量反射镜与快速控制反射镜的速度匹配非常重要。陀螺的输出噪声影响两者的速度匹配,于是陀螺输出信号的滤波就成了首要的问题。通过对三种滤波方法的研究,结果表明:小波收缩去噪具有更好的信噪分离效果。     

降低连接器内电磁干扰的方法分析

基于对任一接插件的干扰只来自最邻近接插件的假设,对连接器内部的电磁干扰建模,模型内接插件间的互耦电容用矩量法进行计算,根据模型的特点采用三角函数做匹配函数简化了计算过程并提高了计算精度.求出敏感接插件周围的接插件全部为信号线时的单位长度参数,不同状态的实现只需通过负载的调节即可,使对不同连接的模拟变得简单易行.对什么时候会在敏感件上产生最大和最小的干扰,以及周围信号的多少对干扰的影响都进行了讨论,以S参数和时域波形的形式给出模拟结果.模拟对正确地连接接插件,降低相互干扰有参考价值.     

Appropriate method of core selection and crosstalk optimization in single-mode homogeneous multicore fiber

The approach for homogeneous core structure design and selection based on low crosstalk, low dispersion, and acceptable mode effective area have been explored. The forward and backward crosstalk behaviors with respect to wavelength, fiber bending radius, and twisting rate in 12-core, and 21-core single-mode trench-assisted homogenous multicore fiber have been analyzed. The new expression for forward crosstalk under bending and twisting conditions has been derived using the conventional method. For the analysis and optimization of crosstalk, three different core structures are considered, it helps to draw the attention to select the appropriate core structure model for multicore fiber, which follows the standards used in telecom services.     

Analysis of crosstalk and field coupling to lossy MTLs in a SPICEenvironment

This paper proposes a circuit model for lossy multiconductor transmission lines (MTLs) suitable for implementation in modern SPICE simulators, as well as in any simulator supporting differential operators. The model includes the effects of a uniform or nonuniform disturbing field illuminating the line and is especially devised for the transient simulation of electrically long wideband interconnects with frequency dependent per-unit-length parameters. The MTL is characterized by its transient matched scattering responses, which are computed including both dc and skin losses by means of a specific algorithm for the inversion of the Laplace transform. The line characteristics are then represented in terms of differential operators and ideal delays to improve the numerical efficiency and to simplify the coding of the model in existing simulators. The model can be successfully applied to many kinds of interconnects ranging from micrometric high-resistivity metallizations to low-loss PCBs and cables, and can be considered a practical extension of the widely appreciated lossless MTL SPICE model, which maintains the simplicity and efficiency