利用非线性光纤环镜160Gb/s到10Gb/s解时分复用

研究了160 Gb/s光时分复用(OTDM)系统的解复用技术.针对160 Gb/s速率的特点,对高非线性光纤(HNLF)的光纤环镜(NOLM)特性及解复用进行了数值仿真.计算了低信号光时间抖动下解复用误码特性对时钟与信号的走离及时钟功率的依赖关系.计算了三种走离值消光比随时钟功率增加的变化趋势并给出:存在一个能获得最大的解复用窗口消光比、并能降低相邻信道串扰的合适的时钟功率范围.利用自制的基于电吸收调制器和压缩技术的超短光脉冲源建立了160 Gb/s OTDM实验系统,测量了不同信号光功率下NOLM的消光比,它基本不随信号增大而变化,在信号功率为7.3 dBm时仍大于23 dB.利用上述装置实现了无误码的160 Gb/s到10 Gb/s全光解复用.     

基于光电反馈环单元时钟提取与解复用的160Gb/s OTDM信号100km传输

提出了一种能够同时对高速光时分复用技术信号解复用与时钟提取的光电反馈环单元.在接收端,采用光电反馈环单元,信号单次通过即可同时完成160Gb/s到10Gb/s的解复用与时钟提取:两级电吸收调制器级联工作方式缩减了采样窗口宽度,满足了解复用小于6.25ps超窄采样窗口的要求;而闭合环路的锁相同步工作方式,使所提取的时钟信号抖动(JitterRMS)由2.4ps降至450fs.基于该结构,实验上成功实现了无误码的100km160Gb/s光时分复用技术传输及传输后无误码地解复用与时钟提取,功率代价小于3dB.     

基于电吸收调制器的高速时钟信号的提取

对高速光时分复用系统中(2×10 Gb/s)基于电吸收调制器(EAM)的注入光电混合振荡器的时钟提取方法进行了实验验证. 实验证明,光电混合振荡器必须保证一定的增益才能提取出时钟,在此基础上,无论光电混合振荡器内或外的光功率的增加,将增加提取时钟的幅度,减小提取时钟的时间抖动.当偏置电压一定时,射频幅度增加,则电吸收调制器的窗口变窄,提取时钟幅度增大,抖动减小.     

基于光电反馈环单元时钟提取与解复用的160 Gb/s OTDM 信号100 km传输

提出了一种能够同时对高速光时分复用技术信号解复用与时钟提取的光电反馈环单元.在接收端,采用光电反馈环单元,信号单次通过即可同时完成160 Gb/s到10 Gb/s的解复用与时钟提取：两级电吸收调制器级联工作方式缩减了采样窗口宽度,满足了解复用小于6.25 ps超窄采样窗口的要求|而闭合环路的锁相同步工作方式,使所提取的时钟信号抖动（Jitter RMS）由2.4 ps降至450 fs.基于该结构,实验上成功实现了无误码的100 km 160 Gb/s光时分复用技术传输及传输后无误码地解复用与时钟提取,功率代价小于3 dB.     

光时分复用(OTDM)系统中基于电吸收调制器(EAM)的短脉冲光源及解复用器的设计考虑

研究了电吸收调制器（ＥＡＭ） 的衰减随外加反向电压增加而指数增加的情形下,短脉冲光源的脉冲输出和解复用器的开关窗口对ＥＡＭ 的消光效率、反向ＤＣ 偏置电压以及正弦ＲＦ 驱动信号的幅度等参量的依赖关系－ 在基于ＥＡＭ 的短脉冲光源中,输出脉冲的消光比等于ＥＡＭ 消光效率η与正弦驱动电压峰峰值Ｖｐｐ 的乘积,输出光脉冲的消光比和脉宽均与ＥＡＭ 的反向偏置电压无关,但输出脉冲的峰值功率与η、Ｖｐｐ 和Ｖｂ 都有关系－ 在基于ＥＡＭ的解复用器中,为了使解复用器的开关窗口近似为矩形,可利用ＥＡＭ 的削波效应,使Ｖｐｐ／２＞ Ｖｂ－ 在ＥＡＭ 的消光效率η已知时,通过仔细设计反向ＤＣ 偏置电压Ｖｂ 和正弦驱动电压的峰峰值Ｖｐｐ ,达到ＯＴＤＭ 解复用器所需要的开关窗口形状、宽度和消光比－     

40 Gbit/s非等幅编码光时分复用传输系统

4× 10Gb s非等幅编光时分复用 (OTDM)传输系统采用增益开关分布反馈式激光器 (GS DFB)产生超短光脉冲 ,通过色散补偿光纤 (DCF)和梳状色散光纤链 (CDPF)实现了脉冲的线性和非线性压缩 ;利用啁啾光纤光栅实现色散补偿 ;在接收端 ,利用电吸收调制器 (EAM)实现了光时分复用信号的解复用 ;同时采用非等幅编码方案提取帧时钟。整个系统经过 12 2km的G .6 5 2光纤传输之后 ,误码率小于 10 - 9。     

偏分复用系统信道串扰的理论模型及消除方案

建立了偏分复用(PDM)系统中信道串扰的数学模型,并提出了消除该串扰的方案,即用解复用端一路光信号的射频(RF)功率作为反馈信号以监测光信号在链路中偏振态的变化和在接收端的串扰情况,用粒子群优化(PSO)算法作为逻辑控制单元的算法,控制偏振控制器以消除信道间的串扰。数值仿真了RF功率与信道串扰大小之间的关系,并在2×50Gb/s偏分复用-差分正交移相键控(PDM-DQPSK)传输系统平台上仿真验证了消除串扰方案的效果。结果表明该方案能够大幅降低系统误码率,改善系统性能。     

自由空间微闪耀光栅解复用器

波分复用/解复用器件在光纤通信中具有重要的应用。设计了一种自由空间的微闪耀光栅解复用器,通过对其衍射光场的复振幅分布的研究,得到了满足1级闪耀输出的光栅方程,实现了复合波长信号光在空间上的解复用。通过对微闪耀光栅解复用器的衍射效率和串扰进行分析后表明,微闪耀光栅解复用器具有很高的衍射效率,信号间串扰非常小,而且元件尺寸小,结构紧凑,集成度高,在光通信和光信息处理中具有一定的应用价值。     

一种通带平坦的粗波分复用/解复用器件的研制

随着粗波分复用(CWDM)系统在城域网和接入网中日益广泛的应用,人们对粗波分复用／解复用器的研究也逐渐展开。报道了一种8通道波长间隔为20nm的粗复用／解复用器。该器件基于阵列波导光栅(AWG)原理设计,利用平面光波导技术(PLC)制作,采用多模干涉输入结构和“S”形阵列波导结构,实现了较宽的通带宽度和较低的串扰。实验测得1dB带宽大于10nm,相邻串扰大于24dB,非相邻串扰大于32dB。介绍了其设计原理和制作过程,给出了光束传播法(BPM)数值模拟结果,并和实验结果进行了对比。     

半导体光放大器引起的串扰及其抑制技术

由于半导体光放大器(SOA)的增益饱和效应,在波分复用系统中.每个信道的增益受到复用的其它信道的影响.SOA引起的各信道之间的串扰严重限制了其应用.理论研究了SOA增益饱和效应引起的信道间串扰.数值模拟了多路信道复用时系统的误码率随复用信道数和光功率的变化情况,发现随着复用信道数的增加SOA增益饱和引起的信道间串扰越来越严重.对SOA中串扰的抑制方法进行了理论和实验研究.数值模拟发现连续光注入可以抑制输出功率的波动,从而减小误码率,当复用10个信道时,连续光注入可以使功率代价减小2 dB;实验验证了两信道的40 Gb/s系统中,注入连续光可以减少SOA引起的信道间串扰.     

光时分复用(OTDM)系统中基于电吸收调制器(EAM)的短脉冲光源及解复用器的设计考虑

研究了电吸收调制器(EAM)的衰减随外加反向电压增加而指数增加的情形下,短脉冲光源的脉冲输出和解复用器的开关窗口对EAM的消光效率、反向DC偏置电压以及正弦RF驱动信号的幅度等参量的依赖关系.在基于EAM的短脉冲光源中,输出脉冲的消光比等于EAM消光效率η与正弦驱动电压峰峰值V_pp的乘积,输出光脉冲的消光比和脉宽均与EAM的反向偏置电压无关,但输出脉冲的峰值功率与η、V_pp和V_b都有关系.在基于EAM的解复用器中,为了使解复用器的开关窗口近似为矩形,可利用EAM的削波效应,使V_pp/2>V_b.在EAM的消光效率η已知时,通过仔细设计反向DC偏置电压V_b和正弦驱动电压的峰峰值V_pp,达到OTDM解复用器所需要的开关窗口形状、宽度和消光比.     

Optical time division multiplexing at 160 Gbps using MZI switching

Many lower-speed data streams can be multiplexed into one high-speed stream by means of optical time division multiplexing (OTDM), such that each input channel transmits its data in an assigned time slot. The simulation is performed by a fast multiplexer switch (mux). The routing of different data streams at the end of the TDM link is performed by a demultiplexer switch (demux) and this demultiplexer is employed using MZI switch as it consists a semiconductor optical amplifier (SOA) and an optical coupler. In this paper four channel OTDM is simulated at 40 Gbit/s and further the impact of the signal power, pulse width and control signal power on BER is investigated.     

Investigation of 2D-photonic crystal resonant cavity based WDM demultiplexer

In this attempt, Two Dimensional Photonic Crystal (2DPC) Quasi Square Ring Resonator (QSRR) based four channel demultiplexer is proposed and designed for Wavelength Division Multiplexing systems. The performance parameters of the demultiplexer such as transmission efficiency, passband width, line spacing, Q factor and crosstalk are investigated. The proposed demultiplexer is composed of bus waveguide, drop waveguide and QSRR. In the proposed demultiplexer, the output ports are arranged separately in odd and even number, where an odd number of ports are located on the right side and even number of ports are located on the left side of the bus waveguide that are used to reduce the channel interference or crosstalk. Further, the refractive index of rods around the center rod is increased linearly one to another in order to improve the signal quality. The resonant wavelengths of the proposed demultiplexer are of 1521.1?nm, 1522.0?nm, 1523.2?nm and 1524.3?nm, respectively. The footprint of the device is of 180.96?μm². Then, a four channel point to point network is designed and the proposed four channel demultiplexer is implemented by replacing a conventional demultiplexer. Finally, functional parameters of the network, namely, BER, receiver sensitivity and Q factor are estimated by varying the link distance. This attempt could create new dimensions of research in the domain of photonic networks.     

Design and optimization of photonic crystal based eight channel dense wavelength division multiplexing demultiplexer using conjugate radiant neural network

In this paper, two dimensional photonic crystal, based eight-channel demultiplexer is proposed and designed for DWDM applications. The performance parameters of the demultiplexer such as transmission efficiency, channel spacing, spectral line width, Q factor, and crosstalk have been evaluated. The proposed demultiplexer comprises of bus waveguide, drop waveguide and parellogram resonant cavity (PRC). The bus waveguide transmits light to the PRC and exits through respective drop waveguide. The PRC consists of a parellogram resonator with a nano ring cavity that is used for dropping eight specific wavelength for ITU-T G 694.1 standard with 50 GHz channel spacing. The circular ring resonator is placed above the PRC wherein a resonant air hole (Cr) is positioned for desired channel selection. The channel selection is done by altering the radius of the air hole. In addition, a conjugate radiant neural network is implemented for optimizing the radii of resonant air holes to select the required channel wavelength. The proposed device is very compact and it could be considered for implementing the photonic integrated circuits.     

Cascade Grating Structure for Increasing the Channel Number on Holographic Demultiplexer

The expansion capability of the channel number in the optical demultiplexer using two cascaded photopolymer volume gratings is reported. It could be accomplished by designing of two gratings with different spectral range. As a result of the experiment, a 0.4-nm-spaced 130-channel demultiplexer with the channel uniformity of 3.5 dB, the 3 riB-bandwidth of 0.12nm, and the channel crosstalk of-20 dB is experimentally demonstrated.     

Performance analysis of an eight channel demultiplexer using a 2D-photonic crystal quasi square ring resonator

Recent years, the design of photonic crystal (PC) based optical devices is receiving keen interest in research and scientific community. In this paper, two dimensional (2D) PC based eight channel demultiplexer is proposed and designed and the functional characteristics of demultiplexer namely resonant wavelength, transmission efficiency, quality factor, spectral width, channel spacing and crosstalk are investigated. The demultiplexer is designed to drop the wavelength centred at 1537.6 nm, 1538.5 nm, 1539.4 nm, 1540.4 nm, 1541.2 nm, 1541.9 nm, 1542.6 nm and 1543.1 nm. The proposed demultiplexer is primarily composed of bus waveguide, drop waveguide and quasi square ring resonator. The quasi square ring resonator and square ring micro cavity (inner rods) are playing a vital role for a desired channel selection. The operating range of the devices is identified through a photonic band gap (PBG) which is obtained using a plane wave expansion (PWE) method. The functional characteristics of the proposed demultiplexer are attained using a 2D finite difference time domain (FDTD) method. The proposed device offers low crosstalk and high transmission efficiency with ultra-compact size, hence, it is highly desirable for DWDM applications.     

Linear system model for planar concave grating demultiplexer

A linear system model for planar concave grating demultiplexer is developed based on the scalar diffraction theory. With this model the system can be simulated by using Fourier transform. Many device performances such as dispersion features, N × N interconnection, channel uniformity, insertion loss, crosstalk can be estimated or optimized. Furthermore, the behavior of aberration is included in the generalized model.     

基于夹层结构的偏振无关1×2定向耦合型解复用器的设计

提出一种基于夹层结构的偏振无关1×2定向耦合型解复用器,用于分离1310 nm和1550 nm两个波长.通过合理选择夹层结构芯区的折射率及波导间隙,可以调节同一波长两个正交偏振模的耦合长度相等,实现偏振无关;通过合理选择夹层结构波导宽度,可以使两个波长分别从不同输出波导端口输出,实现解复用功能.运用三维有限时域差分法进行建模仿真,对结构参数进行优化,并对器件性能进行了分析.结果表明:该器件定向耦合波导的长度为23μm,插入损耗低至0.1 dB,输出波导间的串扰低至–26.23 dB,3 dB带宽可达290 nm和200 nm.另外,本文提出的器件采用Si3N4/SiO2平台,可有效减小波导尺寸,提高集成度,不仅实现了偏振无关,而且结构紧凑、损耗低,在未来的集成光路中具有潜在的应用价值.     

Analysis method of the effect of fabrication errors on a planar waveguide demultiplexer

The impact of fabrication errors on a planar waveguide demultiplexer is analyzed based on an analytical method. The explicit expression of the transfer function taking into account phase and amplitude errors is presented in order to analyze the loss and crosstalk of the demultiplexer caused by fabrication errors. A basic requirement for the demultiplexer with a certain crosstalk criterion can be easily obtained. Using an etched diffraction grating demultiplexer as an example, it is shown that the analytical results have a good agreement with results from a numerical method.