频谱分割DWDM无源光网络系统串扰实验研究

设计实现了基于宽光源频谱分割密集波分复用无源光网络(DWDM-PON)的实验系统。针对于相邻信道和非相邻信道串扰,通过串扰理论模型分析、系统实验测试得出的丢包率和光谱图比较了二者的影响;对比了理论和实验中DWDM-PON系统的串扰功率代价。结果表明:在信道间隔为0.8nm、速率为125Mbit/s的情况下,相邻信道串扰带来的光功率代价约为0.2dB;相邻信道引起的串扰远大于非相邻信道引起的串扰,非相邻信道引起的串扰影响可以忽略。     

垂直双抽运结构PM-OFDM信号对全光波长变换系统的影响

对垂直双抽运结构的偏振复用信号在半导体光放大器(SOA)中的全光波长变换(AOWC)进行了研究。理论分析了激光器线宽对此系统性能的影响,仿真研究了偏振复用-正交频分复用(PM-OFDM)信号在此系统中传输的性能。仿真结果显示,当系统的光信噪比为10dB时,10Gbit/s的PM-OFDM信号经过SOA中的四波混频效应后,在接收端能够实现无串扰偏振不敏感PM信号的接收,其中x和y方向对应的系统误码率分别为1.16×10-4和1.06×10-5。仿真结果表明激光器线宽,OFDM信号的子载波个数,信道功率,以及OFDM调制格式均与系统波长转换效率有关,且仿真结果与理论推导结果一致。     

独立可寻址小间距二极管激光器阵列

独立可寻址小间距二极管激光器阵列将在激光打印机、光盘扫描器、光互联之类应用中发挥作用。要制造此类实用器件,必须使激光条间的串扰最小。加州施乐研究中心设计了一个四元件、独立可寻址的785nm激光器阵列,使用纯氧化物约束脊形波导以达到7μm间距。激光阈值电流小于8mA,每面每信道的差分量子效率超过35%,两束激光间的串扰低于5%。对于不相邻的激光条,串扰还要低些,如第二条与第四条相距14μm,它们之间的串扰低于2%。研究人员称,制造这样的器件要比建造常规的绝缘层约束脊形波导激光器容易得多,因为纯氧化物只在脊形波导的侧壁形成,无…     

一种改进的基于频率选路的DWDM-ROF系统

设计了一个基于频率选路的DWDM-ROF系统。通过30 GHz射频信号驱动相位调制器,对4个间隔为100 GHz的光信道进行双边带调制,产生12个光信道。采用分插复用器将边带分成两组,一组边带分别加载2.5 Gb/s的数据,另一组不做任何变化,然后两路共同耦合进入下行光纤传输50 km,此方案最多可以解复用至6个基站分别接收毫米波信号后供天线发射,并且可以对任意信道进行选路复用。结果表明,通过4路的信道产生6路的毫米波信号,具有较高的频谱效率,同时系统信道间串扰对系统影响不大。     

调制特性对WDM系统中拉曼串扰的影响

从调制统计特性对受激拉曼串扰的作用出发,给出了基于强度调制-直接检测的WDM光通信系统中拉曼串扰的概率密度分布：并从该概率密度分布特征分析了不同波长信道下的受激拉曼串扰程度,结果发现：不同波长信道下,其受激拉曼串扰程度有所不同,且在中间影响最小,而最短波长时影响最大。最后给出了各信道误码率与拉曼串扰期望值成互补误差的函数关系。     

允许1010信道的级联滤波器

日本Tokai的NTT光电技术实验室的研究人员论证了可用于光远程通信的1010信道滤波器，他们相信这将使超高密度网络成为可能。去年六月份的IEEE PhotonicsTechnology Letters报道了该装置。他们将10个10GHz信道间距的1×160阵列波导光栅与一个1THz信道间距的1×10阵列波导光栅相连接。该滤波器覆盖了C-和L-波段，每个信道显示有13~29dB的损耗，研究人员希望能将损耗降到9dB。邻近信道间串扰和累积信道间串扰变化分别为-32~-25dB和-24~-18dB。允许1010信道的级联滤波器@余婷…     

50/100GHz AWG型光学梳状滤波器的设计与制备

以Si基SiO2平面光波导为基础,设计并制备了50/100GHz AWG型光学梳状滤波器．制备得到的AWG型光学梳状滤波器可以覆盖1520～1585nm的波长范围,共有160个信道．功率输出不均匀度＜0.5dB,插入损耗＜8dB,相邻通道的串扰＞13dB,在距离中心频率最远的信道,输出频率偏离ITU标准15GHz．分析了影响器件串扰和信道频率偏移的原因,并提出了相应的解决办法．     

50/100GHz AWG型光学梳状滤波器的设计与制备

以Si基SiO2平面光波导为基础,设计并制备了50/100GHz AWG型光学梳状滤波器.制备得到的AWG型光学梳状滤波器可以覆盖1520～1585nm的波长范围,共有160个信道.功率输出不均匀度＜0.5dB,插入损耗＜8dB,相邻通道的串扰＞13dB,在距离中心频率最远的信道,输出频率偏离ITU标准15GHz.分析了影响器件串扰和信道频率偏移的原因,并提出了相应的解决办法.     

光网络中大功率信号引起的带内串扰攻击研究

分析了光网络中大功率信号引起的带内串扰攻击,攻击信号功率和光开光串扰系数是带内串扰攻击对用户信号质量产生破坏影响的主要因素.在VPI仿真软件中搭建实验系统,以误码率为评价指标,定量研究了带内串扰攻击对用户信号质量的影响及其攻击传播能力.结果表明,当光开关串扰系数为-20 dB、初始攻击信号功率高于用户信号功率20 dB以上时,在OXC1处,经过第一级和第二级光开关的用户信号会受到攻击影响,经过第三级光开关的用户信号几乎不受攻击影响.带内串扰攻击具有一定的攻击传播能力,当初始攻击信号功率高于用户信号功率27dB、光开光串扰系数为-20 dB时,初始攻击信号的攻击能力可传播至OXC3,同时,二阶攻击信号基本不具备攻击传播能力.     

带间与带内串扰的理论分析与实验研究

在波分复用(WDM)系统中不同信道之间的串扰将恶化每路信号的消光比,而多波长光交叉连接网络中还会出现带内串扰的情况,它所产生的拍频噪声对系统的影响远大于带间串扰。从不同的角度分析了这两种串扰,理论分析的结果与实验现象吻合良好。     

Impact of laser linewidth on optical channel spacing requirements for multichannel FSK and ASK systems

The sensitivity penalty is evaluated for amplitude-shift-keyed and frequency-shift-keyed multichannel coherent systems that use lasers with linewidths which are a significant fraction of the bit rate. The study was conducted for both ASK and FSK systems using a single-filter receiver with nonsynchronous detection. For FSK systems, both NRZ (nonreturn-to-zero) and alternate mark inversion (AMI) signal formats were studied. The optical channel spacing is strongly determined by the laser linewidth. For example, with the FSK-NRZ data rate of 150 Mb/s, the optical channel spacing which gives 1-dB crosstalk penalty is 4 GHz when the intermediate frequency linewidth is 50 MHz (laser linewidth is 25 MHz), as opposed to 1.8 GHz when the linewidth is negligible.<>     

Influence of adjacent channel interference on thefrequency-modulated WDM optical communication system

The effect of adjacent channel interference on the frequency modulated wavelength division multiplexing (FM-WDM) optical communication system is analyzed in this paper. This system uses injection-locked optical discriminator at the output for the demodulation of FM channels. Adjacent channel interference results in crosstalk in the FM-WDM communication system which has been calculated. Dependence of crosstalk on the channel spacing, received signal power in a particular channel, and linewidth enhancement factor of the slave laser incorporated in the optical discriminator has been numerically investigated. The injection-locked discriminator has a typical output crosstalk level of -50 dB for a channel spacing of 100 GHz with optical injection level of -30 dB into the slave laser and is a suitable subsystem to be used in FM-WDM communication system     

基于硅纳米线波导的16通道200GHz阵列波导光栅

设计了基于硅纳米线波导的16通道,通道间隔为200GHz的阵列波导光栅(AWG)。传输函数法模拟了器件传输谱,结果表明器件的通道间隔为1.6nm,通道间串扰为31dB。器件利用SOI材料,由193nm深紫外光刻工艺制备。光谱测试结果分析表明,通道串扰为5-8dB,中心通道损耗2.2dB,自由光谱区长度24.7nm,平均信道间隔1.475nm。详细分析了器件谱线畸变的原因。     

16 channel 200 GHz arrayed waveguide grating based on Si nanowire waveguides

A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed.The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB.The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate.The demultiplexing characteristics are observed with crosstalk of 5-8 dB,central channel’s insertion loss of 2.2 dB,free spectral range of 24.7 nm and average channel spacing of 1.475 nm.The cause of the spectral distortion is analyzed specifically.     

Crosstalk penalty in a two-channel ASK heterodyne detection system with non-negligible laser line width

Crosstalk penalties as a function of channel spacing were measured in a two-channel ASK heterodyne system using 1·55?m DFB lasers. For an IF linewidth/bit rate ratio of 0.5, the channel spacing in the IF domain must be greater than 13 times the bit rate for negligible crosstalk penalty.     

Four-Wave Mixing Crosstalk Measurement in a Highly Doped L-Band Erbium-Doped Fiber Amplifier by Using Half of the Signal Channels

We propose a four-wave mixing (FWM) crosstalk measurement method for a signal with 50 GHz spaced wavelength channels in a highly doped L-band erbium-doped fiber amplifier (EDFA). The method uses the crosstalk measured by using a signal with 100 GHz spaced wavelength channels. This approach is based on analyses of the channel spacing dependence of FWM signal generation and the effect of the gain evolution of each signal channel along the EDF during FWM signal generation at a specific frequency. It is shown that reducing the channel spacing from 100 to 50 GHz has little impact on the efficiency of FWM generation if the gain evolution is the dominant term in FWM generation. It is also shown that the contributing ratio of the gain evolution of each channel is almost the same for the two signals. These results enable us to develop a measurement method for estimating the FWM crosstalk in an L-band EDFA applied to a wavelength-division multiplexing system with a 50 GHz spaced signal by using a 100 GHz spaced signal and a compensation factor. The validity of the measurement method is successfully demonstrated experimentally.      

Investigation of adjacent channel crosstalk in multichannelmonolithically integrated 1.55 μm photoreceiver arrays

We have investigated adjacent channel crosstalk in 3-, 8-, and 16-channel InP-based monolithically integrated p-i-n/HBT photoreceiver arrays, with a channel bandwidth of 11 GHz. By using a novel monolithically integrated radiation shield, we have been able to reduce the crosstalk to -35 dB at 10 GHz. These parameters represent the best performance in multichannel integrated photoreceiver arrays. The two main components of crosstalk are found to be radiation crosstalk and electrical crosstalk and these are separately dependent on interchannel spacing and single- or dual-source biasing schemes. An electromagnetic full-wave solution shows that the measured crosstalk in arrays without the radiation shield could be dominated by radiation crosstalk, which can be modeled as a capacitive coupling between adjacent channels. Similarly, electrical crosstalk can be modeled by equivalent parasitic resistive and inductive elements. Values of these circuit elements have been determined by analyzing experimental data     

Low-crosstalk 3.125 Gbit/s×four-channel LD array withisolated electrodes for parallel optical communications

An array of 1.3 μm FP-LDs with their anodes and cathodes separated channel by channel was developed to suppress interchannel electric crosstalk at high frequency. Low crosstalk of less than -30 dB was obtained between neighbouring LDs at 3.125 GHz. This is sufficiently low that BER characteristics observed under asynchronous operation of a four-channel LD array were found to be no worse than those under single channel operation     

Technique for widening passband of wavelength router

A new method to broaden the passband of arrayed-waveguide grating routers is proposed. A sinc(x) intensity distribution is formed in the array by a slot etched in the input star coupler. A 3 dB bandwidth of 65 GHz is obtained for a 100 GHz channel spacing and the adjacent channel crosstalk is less than 25 dB.     

Flat spectral response arrayed-waveguide grating multiplexer withparabolic waveguide horns

An eight-channel flat spectral response arrayed-waveguide grating multiplexer with parabolic waveguide horns has been fabricated on a planar lightwave circuit (PLC). A double-peaked intensity distribution is formed at the slab interface by the parabolic waveguide horn. A 1 dB bandwidth of 98 GHz, 3 dB bandwidth of 124 GHz and 20 dB bandwidth of 196 GHz are obtained for 200 GHz channel spacing. The crosstalk to neighbouring channels is less than -27 dB and the on-chip insertion losses range from 6.1 to 6.4 dB, respectively