Pulse Propagation with Self-Phase Modulation in Nonlinear Chiral Fiber and Its Applications

From Maxwell＇s equations and Post＇s formalism, a generalized chiral nonlinear Schr6dinger equation （CNLSE） is obtained for the nonlinear chiral fiber. This equation governs light transmission through a dispersive nonlinear chiral fiber with joint action of chirality in linear and nonlinear ways. The generalized CNLSE shows a modu- lation of chirality to the effect of attenuation and nonlinearity compared with the case for a conventional fiber. Simulations based on the split-step beam propagation method reveal the role of nonlinearity with cooperation to chirality playing in the pulse evolution. By adjusting its strength the role of chirality in forming solitons is demonstrated for a given circularly polarized component. The application of nonlinear optical rotation is also discussed in an all-optical switch.

Multiparameter performance monitoring of pulse amplitude modulation channels using convolutional neural networks

A designed visual geometry group(VGG)-based convolutional neural network(CNN)model with small computational cost and high accuracy is utilized to monitor pulse amplitude modulation-based intensity modulation and direct detection channel performance using eye diagram measurements.Experimental results show that the proposed technique can achieve a high accuracy in jointly monitoring modulation format,probabilistic shaping,roll-off factor,baud rate,optical signal-to-noise ratio,and chromatic dispersion.The designed VGG-based CNN model outperforms the other four traditional machine-learning methods in different scenarios.Furthermore,the multitask learning model combined with MobileNet CNN is designed to improve the flexibility of the network.Compared with the designed VGG-based CNN,the MobileNet-based MTL does not need to train all the classes,and it can simultaneously monitor single parameter or multiple parameters without sacrificing accuracy,indicating great potential in various monitoring scenarios.

Intense,wideband optical waveform generation by self-balanced amplification of fiber electro-optical sideband modulation

We demonstrate a simple method to obtain accurate optical waveforms with a gigahertz-level programmable modulation bandwidth and a watt-level output power for wideband optical control of free atoms and molecules.Arbitrary amplitude and phase modulations are transferred from microwave to light with a low-power fiber electro-optical modulator.The sub-milliwatt optical sideband is co-amplified with the optical carrier in a power-balanced fashion through a tapered semiconductor amplifier(TSA).By automatically keeping TSA near saturation in a quasi-continuous manner,typical noise channels associated with pulsed high-gain amplifications are efficiently suppressed.As an example application,we demonstrate interleaved cooling and trapping of two rubidium isotopes with coherent nanosecond pulses.

Research of photonic-assisted triangular-shaped pulses generation based on quadrupling RF modulation

We propose an approach to generate optical triangular-shaped pulse train with tunable repetition rate using quadrupling radio frequency(RF)modulation and optical grating dispersion-induced power fading.In this work,a piece of chirped fiber Bragg grating(FBG)is employed as the dispersive media to remove the undesired 8th harmonic in optical intensity.Thus,the generated harmonics of optical intensity can be corresponding to the first two Fourier components of typical periodic triangular pulses.This work also analyzes the impacts of the extinction ratio and the bias voltage drift on the harmonic distortion suppression ratio.After that,the value of the extinction ratio and the range of the bias voltage drift can be obtained.The advantage of this proposal is that it can generate high order frequency-multiplexed optical pulses train which can be applied in all optical signal processing and other fields.

可调谐DFB激光器泵浦的PPLN绿色倍频光源

为研制脉冲宽度、重复频率以及输出功率可调谐至单光子级别的可见光波段高重频纳秒级窄脉冲光源,提出了一种基于增益调制型DFB激光器和PPLN晶体的绿色倍频光源设计方案。通过自制的纳秒级高速驱动电路以脉冲方式驱动DFB激光器产生固定波长的泵浦源;利用光纤半导体衰减器调节衰减量,调制泵浦光强度;采用PPLN晶体作为非线性晶体材料,通过其可调谐特性得到准相位匹配的绿色倍频激光输出。实验结果表明,DFB激光器输出的泵浦光功率和中心波长稳定,脉冲宽度1.02 ns~10.25 ns、工作频率1 Hz~10 MHz连续独立可调,泵浦光功率衰减至-44.61 dB时工作于532.96 nm波段的绿色倍频光输出脉冲平均光子数约为384 N,倍频光-光转换效率9.3%。

Experimental study on generation of high energy few cycle pulses with hollow fiber filled with neon

25 fs pulses with energy up to 0.8 mJ from a multi-pass amplifier system have been spectrally broadened from 460 nm to 950 nm due to strong self-phase modulation(SPM) effect in a gas filled hollow fiber.Using a set of chirped mirrors,the ul-tra-broadband dispersion compensation was achieved,and the compressed pulses reached their transform limit.Under optimized conditions we achieved pulses with duration of 5.1 fs and with energy of 400 μJ,corresponding to the peak power up to 80 GW.

Supercontinuum generation at 1.55 μm in an all-normal dispersion photonic crystal fiber with high-repetition-rate picosecond pulses

We demonstrate the generation of supercontinuum(SC) spectrum covering S+C+L band of optical communication by injecting 1.4 ps optical pulses with center wavelength of 1552 nm and repetition rate of 10 GHz into an all-normal dispersion photonic crystal fiber(PCF) with length of 80 m. The experimental results are in good agreement with the numerical simulations, which are used to illustrate the SC generation dynamics by self-phase modulation and optical wave breaking(WB).

基于DP-BPSK调制器的四级光信号生成方案

面对短距离光通信中不断增长的数据流量需求,以及高昂的高速数据中心互连成本,文章提出了一种基于双偏振二进制相移键控(DP-BPSK)调制器的四级光信号生成方案。所提方案的实验架构包括激光二极管(LD)、由二进制数据驱动的DP-BPSK调制器、偏振控制器(PC)和偏振器,无需数字模拟转换器,结构简单易于实现。为验证所提方案的可行性,采用方案生成了四级脉冲振幅调制(PAM-4)信号,并将生成的PAM-4信号以不同的数据速率在65km标准单模光纤(SSMF)上传输,传输信号的眼图和误码率实验结果表明信号具有较高质量。因此,所提方案在未来短距离光通信中具有良好的应用潜力。

瑞利布里渊光时域分析系统中电光调制器的理论模型与实验研究

瑞利布里渊光时域分析系统能够以非破坏性方式实现单光源、单端工作,利用强度型电光调制器同时调制脉冲基底和脉冲信号是获得该系统所需连续光和脉冲光的关键技术.本文理论分析、仿真和实验研究了一种将脉冲信号输入到电光调制器偏置端、微波信号输入到电光调制器射频端同时调制脉冲基底和脉冲信号的新调制方法,探讨了电光调制器用于瑞利布里渊光时域分析系统时的最佳工作点问题.结果表明,当调制脉冲基底和脉冲时分别将电光调制器偏置在传输曲线的谷点和峰点,并根据实际系统的组成和性能指标要求选择合适的微波调制信号幅度,可获得满足瑞利布里渊光时域分析系统要求的连续光和脉冲光.本文的研究结果为瑞利布里渊光时域分析系统的最佳化设计提供了理论依据.

基于啁啾FBG的三角形光脉冲发生器的优化设计

提出了利用啁啾光纤布拉格光栅(FBG)和马赫增德尔调制器产生三角形光脉冲的优化方案。方案采用FBG模拟单模光纤的色散特性,结合光载波抑制调制产生了三角形光脉冲,并通过仿真分析,选择FBG的长度、调制深度、适当的折射率切趾函数对三角形光脉冲的线性特征进行了优化。仿真结果表明,在同一啁啾系数下,产生的三角形光脉冲的失真程度随啁啾光纤光栅的调制深度增大而增大,光栅长度、折射率切趾函数对三角形光脉冲的影响也比较明显。与现有系统相比,由于将FBG引入系统,省去长距离的光纤,优化方案系统结构更为简单,三角形光脉冲线性特征更好。

光纤型输液器液位自动报警装置

利用光纤传输以及液面全内反射方式,并采用光源脉冲调制和锁相环信号检测技术,研制了一种光纤型液位自动报警装置,已经用于输液器输液终了时的远距离自动报警。该装置抗干扰能力强、安全可靠、成本低且易于网络化,并可以用于其它种类液位的非接触远距离监测。

声光调Q纳秒脉冲全光纤超连续谱光源

基于声光调Q技术的纳秒脉冲光纤激光超连续谱光源系统为全光纤结构,使用普通的传能光纤作为超连续谱的产生介质,通过改变泵浦功率和调制频率,可获得不同的超连续谱输出。实验结果表明:泵浦功率越大,调制频率越低,传能光纤越长,光谱展宽越宽。当传能光纤为200m、调制频率为1kHz、占空比为1.0%、泵浦功率为4.68W时,获得谱线宽度超过700nm的超连续谱输出。该系统可作为超连续谱光源的一种参考方案。

任意波形脉冲泵浦下掺铒光纤的自发辐射

为了突破以往研究的波形局限,探究任意波形脉冲泵浦下掺铒光纤的自发辐射特性,从速率方程组出发,采用分时段计算的方法得到各能级粒子数及自发辐射平均功率的表达式.仿真和实验表明,泵浦光毛刺对自发辐射光的影响较小,具有类似"高频滤波"的特性;泵浦功率较大时自发辐射光的波形与泵浦波形接近,该研究结果可以用于光纤激光器的全光调制.理论分析与实验结果相符合,证明了理论的可靠性.

一种高速光纤声光调制器

该文介绍了应用于光纤传感系统中的高速光纤声光调制器的设计和应用。分析了影响光纤声光调制器调制速度的因素,介绍了高速光纤声光调制器的设计方法。最后采用氧化碲(TeO_2)晶体和小束腰光纤准直器得到工作波长1 550nm、光脉冲上升时间23.9ns、插入损耗2.9dB、通断消光比53dB的高速光纤声光调制器。

光纤中基于互相位调制效应的超短光脉冲对的产生

提出一种在单模光纤正常色散区由连续波产生超短光脉冲对的新方法 即让连续波和一个波长位于光纤负色散区的高阶孤子在光纤中同时传输 ,互相位调制效应和群速度色散效应的互相作用能使连续波演化成超短光脉冲对 本文还通过计算机模拟 ,对该方法进行了全面的考察和分析 结果表明 。

大容量级联式电池储能功率调节系统中多脉冲驱动技术研究

出于高压隔离目的,大容量级联式电池储能系统中,一般采用光纤传输驱动脉冲信号。由于H桥单元个数众多,驱动脉冲数量庞大,为减少光纤使用数量,降低系统成本,提高工作可靠性,采用编解码技术,对多路脉冲驱动信号进行编码后通过一条光纤信号进行串行传输成为一种可行的解决方案。首先分析了PWM脉冲信号的产生算法,在此之上提出针对多路PWM脉冲进行编解码的算法,指定通信协议,采用光纤信号进行串行通信,并将该方案成功应用于一台6 k V,600 k W电池储能功率调节系统(PCS)中,实验结果表明采用该编解码方案使用一条光纤即可完成传统多路光纤传输任务,功率调节系统输出与理论分析一致,电压谐波含量低,并网电流正弦度高,验证了所提的脉冲编解码方案的正确性与可行性。

高精度温控脉宽调制工作方式与频谱问题研究

介绍了几种用于光纤陀螺光源的高精度温度控制的脉宽调制(PWM)工作方式,并分析了这几种工作方式的驱动转换过程。对于脉宽调制方式引入的电磁干扰问题,详细分析了转换交越过程中的输出信号及频谱。研究发现,在脉宽调制工作的交越过程中,输出信号的频率和脉宽是复杂的、无规律的,其谱线位置发生了随机的、不可预测的变化,功率分布不再符合周期矩形脉冲谱特性。针对这种交越随机频谱引入的电磁干扰,提出了几种有效的解决方案,并给出了一种方案的实验验证。

光载超宽带脉冲雷达信号传输性能研究

采用双并行马赫曾德尔调制器产生高斯脉冲一阶微分和二阶微分型超宽带脉冲雷达信号和光载无线电传输技术,通过仿真研究了两种超宽带脉冲雷达信号在标准单模光纤中的传输特性.结果表明,高斯脉冲一阶微分型脉冲随着传输距离的增大而不断展宽,而高斯脉冲二阶微分型脉冲则先压缩后展宽.经100km标准单模光纤传输之后,在传输终端采用色散补偿光纤对传输信号进行不同程度的色散补偿,可获得满足美国联邦通信委员会规范要求的不同宽度高斯脉冲一阶微分和二阶微分型脉冲信号.

单偏振光纤声光调制器

该文介绍了一种全光纤耦合的单偏振声光调制器的设计及应用。理论分析了光纤声光调制器的工作原理,描述了单偏振光纤声光调制器的关键指标(插入损耗、消光比、光脉冲上升时间)的设计方法和单偏振光纤准直器的耦合工艺方法。设计制作了工作在1.06μm波长的高速低插损单偏振光纤声光调制器,其偏振消光比达到42 dB,能有效隔离系统偏振噪声。

一种一体化光纤声光调制器

该文采用光纤声光调制器集成化、低功耗和热仿真设计技术,设计并制作了工作波长1550 nm、光脉冲上升时间16.7 ns、光脉冲延时抖动1.5 ns、电功耗0.72 W(脉冲)、整体尺寸59.56 mm×49.48 mm×14.6 mm的高性能一体化光纤声光调制器。结果表明,该调制器具有体积小及功耗低等优点,对小型化低功耗光纤激光器、激光测风雷达及光纤分布式传感系统的研制有一定促进作用。