Study on a Multiplexer a 40 Gb/s OTDM System

In a 4?0Gb/s OTDM system (optical time-division-multiplication) system, multiplexing devices are key devices. The time interval of four channels of the 40Gb/s OTDM system is 25ps respectively. If the time intervals are no accurate, will induce the system performance to degeneration. In order to make out OTDM device and carry out a transmission experiment in a 40Gb/s OTDM system, a kind of OTDM device is researched. This scheme be used to fabricate multiplex device. Also the device have been used to a 40Gb/s OTDM system. Our experimental results shows that, the multiplex device based on the six 1 optical fiber couplers can be used to multiple at a time domain.That make four 10Gb/s optical signals multiple to 40Gb/s. The time interval error of each of channels is not bigger than 1ps, inserted loss is smaller than 2dB.     

光时分复用系统中单路时钟的提取

提出利用复用信号的时候不均匀性,采用主动光纤锁模激光器,直接从复用后的信号中提取出复用前的时钟光脉冲。考虑到电的时分复用与光的时分复用在机理上的一致性,故初步复用时分复用信号进行实验,成功地从时分复用信号中得到了复用前的时钟光脉冲。此处电的时分复用所得的结论适用于光的时分复用。     

Error-free OTDM demultiplexer using the supercontinuum spectrum-slicing induced clock signal

We experimentally demonstrate an 80-Gb/s optical time-division multiplexing (OTDM) demultiplexing system based on the cross-phase modulation (XPM) effect in high-nonlinearity fibers. The message carried by OTDM signal is loaded onto the probe signal by sampling the OTDM packet with a 10-GHz stable and controllable clock pulse train. The clock signal with ~ 11 ps pulse width is achieved by employing supercontinuum spectrum-slicing technique, which is distinct from that based on mode-locked lasers. The demultiplexed signal is obtained by filtering out the XPM-induced spectral sidebands of the probe signal. The OTDM demultiplexer based on this novel technique shows excellent performances and contributes to a bit error rate of as low as 10⁻⁹.     

等幅均匀复用OTDM信号的单路和群路时钟提取

提出了针对等幅均匀复用的光时分复用信号进行全光时钟提取的一种新方案,理论上分析了该方案的可行性,并给出了各次谐波时钟频率分量大小的表达式.实验上利用该方案成功地从等幅均匀复用的8×2.5 GHz信号中提取出了2.5 GHz单路时钟和20 GHz群路时钟光脉冲.此技术可应用于高速OTDM信号的时钟提取.     

Novel scheme of clock recovery for high-speed OTDM signals based on stimulated Brillouin scattering

A new but simply implemented optical clock recovery scheme for optical time-division multiplexing （OTDM） systems based on stimulated BriUouin scattering （SBS） effect is presented and demonstrated experimentally. According to the unequal-amplitude even-multiplexed OTDM signals, the frame clock is extracted. In addition, the clock with multiple tributary rates is recovered from 160-Gb/s OTDM signal in simulation by utilizing the clock recovery module.     

Performance analysis of OTDM system in the presence of FEC using symmetric Mach-Zehnder switch

Optical time division multiplexing is an emerging and promising alternative for future high-speed photonic networks because of its ability to accommodate higher bit rate and flexible bandwidth. SMZ have been found to be the most suitable switching element than all the available de-multiplexing switches because of compact size, thermal stability, and low-power operation. In this paper, we simulate four channel OTDM systems (all-channel multiplexer and de-multiplexer) with a Mach-Zehnder modulator and an SMZ de-multiplexer to investigate the impact of FEC on the OTDM system. It is observed that the presence of FEC in OTDM transmission can greatly improve the system performance.     

非等幅OTDM信号的全光时钟提取

理论上推导了非等幅均匀复用的OTDM信号中时钟分量与各路脉冲幅度的关系式,并分别从频域和时域的角度给出了利用以半导体光放大器（SOA）作为调制器的锁模光纤激光器进行时钟提取的物理机制,对时钟提取的物理过程给出了形象解释.实验上通过利用锁模光纤激光器成功地从非等幅均匀复用的8×2.5 GHz OTDM信号中提取了2.5 GHz单路时钟和20 GHz群路时钟光脉冲.利用该方案提取的时钟脉冲稳定性好,对偏振态不敏感,是较理想的时钟源.此技术可用于高速OTDM信号的时钟提取.     

Analysis of polarization dependence for OTDM demultiplexers based on four-wavelength mixing in semiconductor optical amplifier

In optical time-division multiplexing (OTDM) systems using the four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) for time demultiplexing, the polarization states of control pulse and OTDM data lights are an important factor in the optical time demultiplexing process, which can influence the bit error rate (BER) of OTDM systems. In this paper, we analyze the effect of light polarization states on the FWM of a SOA, and use a simulation approach to study the BER performance of 100 Gbit/s OTDM systems that use the FWM in a SOA for optical time demultiplexing. It reveals that the BER or Q factor of OTDM systems is dependent on the misalignment θ between the polarization states of OTDM data and control lights. With increasing θ, both the optical power of resulting FWM component and the BER performance (or Q factor) of OTDM systems is degraded. For linearly polarized lights, our results show that the increase of BER and the reduction in Q factor are made smoothly when θ changes its value from 0° to 75°, whereas the degradation of BER and Q factor becomes rapid when θ exceeds 75°. Although the best system BER is obtained for θ = 0°, the BER performance can still tolerate some misalignment θ (e.g., up to 20° in our simulation). This is useful for the engineering design and applications of SOA-based optical time demultiplexers.     

Demonstration of an 8×10-Gb/s OTDM system

An 8×10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroabsorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which generated stable 10-GHz, 2-ps full-width at half-maximum (FWHM) pulse train, an optoelectronic oscillator (OEO) that extracted 10-GHz clock with a timing jitter of 300 fs from 80-Gb/s OTDM signal and a self cascaded EAM which produced a switching window of about 10 ps. A back-to-back error free demultiplexing experiment with a power penalty of 3.25 dB was carried out to verify the system performance.     

Demonstration of feasibility of a complete 160 Gbit/s OTDM system including all-optical 3R

A complete 160 Gbit/s single-channel OTDM system experiment is presented. The OTDM system includes all-optical transmitter, 3R (Retiming, Reshaping, and Reamplification), and receiver. Performance measurements of the single subsystems are also reported. Finally Q-factor measures verify the effectiveness of the whole system.     

Demonstration of a 16×10-Gb/s OTDM system

A 16×10-Gb/s optical time-division-multiplexing (OTDM) system was demonstrated experimentally with a well-designed ultrashort pulse source based on an electro-absorption modulator (EAM) and nonlinear fiber compressor. The obtained 10-GHz stable and pedestal-free pulse train has 2-ps width, high extinction ratio, and low timing jitter. An ultrafast demultiplexer based on a nonlinear optical loop mirror (NOLM) including a commercially available highly nonlinear fiber (HNLF) is employed to demultiplex data signal from 160 to 10 Gb/s. A back-to-back error-free demultiplexing experiment is carried out to verify the system performance.     

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。     

Ultrafast OTDM transmission using novel fiber devices for pulse compression, shaping, and demultiplexing

This paper describes key fiber devices that were used to generate and handle femtosecond optical pulses in the 1.28-Tbit/s OTDM transmission experiment.     

Analysis of a polarisation-maintaining NOLM switch for OTDM applications

We propose a polarisation-maintaining NOLM switch design to be used as optical regenerator or wavelength converter in dense optical time-division multiplexed (OTDM) systems. The Sagnac loop is made of a piece of high birefringence fibre which is cut and cross-spliced in the middle. If pump and probe polarisations are linear and aligned in the co-propagating direction, the cross-splice ensures that the counter-propagating probe beam will be orthogonal to the pump, so that the parasitic cross-phase modulation between counter-propagating beams is minimised. This architecture also allows easy control of the optical phase bias, through squeezing a short section of the fibre, without any other modification of the setup. The performances of the proposed architecture are studied analytically and numerically, and compared with those of conventional schemes. It appears that, although the proposed setup reduces the interaction between counter-propagating beams only by a factor 3, it yields an extinction ratio improvement of a factor 10 or higher in comparison with conventional schemes. If there is substantial walkoff between pump and probe, a 10-fold reduction of the relative intensity noise of the emerging signal is also obtained when the mark ratio of the incoming data is variable.     

Compensating Large PMD by Four Free degrees in an OTDM System

In this paper, by introducing a two-stages polarization mode dispersion (PMD) compensator after a optical fiber link with a large PMD, we compensated over 270ps first-order and 2000ps2 high-order PMD in a optical fiber link with super high PMD. Our experimental results shows that, the compensators based on the two-stages of compensator can be used to PMD compensation in a 20Gb/s OTDM system with 60 km high PMD fiber. Before compensation,270ps DGD is became into max. 7ps after compensation. At simultaneity, the tunable FBG have a function of dispersion compensation.     

面向LOFAR应用的160Gbit/s OTDM试验平台

报告了一个用于低频射频天线网络LOFAR的160 Gbit/s 演示平台.文章介绍了LOFAR网络结构以及用于LOFAR长臂的OTDM/WDM系统结构,回顾并探讨了用于实现160 Gbit/s系统的关键技术,并介绍了实验室中实现该160 Gbit/s OTDM/WDM演示平台所采用的技术方案。出于经济性考虑,所有的关键系统功能都采用自己搭建方案.     

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.     

基于SOA-DI结构的OTDM分组网分组头提取技术

提出了一种基于SOA-DI结构在OTDM网中光分组信头提取的方案,该方案利用半导体光放大器（SOA）的增益饱和效应,通过DI结构干涉实现了2.5Gbit/s 全光信头和40Gbit/s净荷数据的OTDM光分组包信头提取,提取的光分组信头消光比可达16dB以上.给出了理论模型并进行了数值仿真,从理论上对输入脉冲能量和脉宽、SOA的饱和能量、SOA载流子寿命、SOA小信号增益以及DI干涉时延差等重要参量对光分组包信头提取质量的影响做了分析.该方案结构简单,易于集成.     

利用非线性光纤环路镜将20Gb/s的OTDM信号变换26nm

本文利用非线性光纤环路镜成功地将中心波长为1533.9nm的20Gb/s(8×2.5Gb/s)的OTDM信号变换到1553.3nm和1560.3nm,变换的最大间距达26nm,测量了变换后信号光的眼图和光谱图,并对实验结果进行了分析。     

Realizing 20 Gbit/s OTDM Transmission over 50 km True-wave Fiber with Dispersion Compensation

20 Gbit/s OTDM transmission over 50 km true-wave fiber with dispersion compensation was realized for the first time in China. The power penalty is smaller than 8 dB. The following technology problems were solved: the generation and the compression of ultra-short optical pulse; low bits to high bits multiplexer; high bits to low bits demulitplexer; the clock extraction from high speed system, dispersion compensation.