Theoretical analysis on polarization deviation and switch windowoptimization in nonlinear optical loop mirror demultiplexer

This paper investigates theoretically two of the dominant issues on a nonlinear optical loop mirror (NOLM) demultiplexer: the sensibility to the polarization deviation between signal and control pulses and the optimization of the switch window width. The complete nonlinear Schrodinger equations concerning the different states of polarization between signal and control lights are firstly established to study the impact of the polarization deviation on the demultiplexed signal. Considering simultaneously the channel crosstalk and the timing jitter between signal and control pulses, the switch window width of NOLM is optimized to achieve the best demultiplexing performance. The theoretical analysis shows that the polarization deviation has to be controlled less than 20° within the bit error rate (BER) of 10^-9 s. The optimal amount of the pulse walkoff is a little less than half of the slot width of the OTDM system     

A Hybrid OTDM Scheme With Enhanced Demultiplexing Performance

We propose a novel hybrid optical time-division multiplexing (OTDM) approach, which contains hybrid modulation formats of return-to-zero on-off keying and return-to-zero differential-phase-shift keying, and investigate its demultiplexing performance. Compared with conventional OTDM with homogenous modulation format, the target demultiplexed channel in a hybrid OTDM signal suffers from much less degradation due to the possible crosstalk from the adjacent channels. We experimentally demonstrate 84.88- to 10.61-Gb/s hybrid OTDM demultiplexing and achieve a relatively wide switching window, which cannot be realized by using the conventional OTDM. Moreover, experimental results at 42.44 Gb/s show a much larger tolerance against timing misalignment in demultiplexing, which further validates the improved demultiplexing performance by using the hybrid OTDM scheme.     

基于三波长SLA的全光解复用器

工作在三波长状态下的SLA作为非线性元件,在光环形镜中实现OTDM信号的解复用,模拟计算表明,在保持光束功率为1W时,SLA恢复时间小于10ps,可从OTDM复用信号中提取出任一路信号,在控制脉冲功率为900mW时,带宽可达100GHz。     

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application     

RZ-DPSK OTDM demultiplexing using fibre optical parametric amplifier with clock-modulated pump

Optical demultiplexing for a 40 Gbit/s RZ-DPSK OTDM signal using a fibre optical parametric amplifier with a sinusoidal-clock-modulated pump is experimentally demonstrated. Less than 1.3 dB power penalty and around 30 dB gain are obtained for all four demultiplexed channels. Superior performance is obtained for the demultiplexed tributaries in RZ-DPSK OTDM systems compared with those in RZOOK OTDM.     

Timing-jitter-free demultiplexing of an all-optical signal processor based on the intensity-dependent self-wavelength conversion of Raman solitons

An all-optical signal processor based on the self-wavelength conversion of Raman solitons is described. The processor consists of an erbium-doped fiber amplifier (EDFA), a highly nonlinear fiber, and an optical bandpass filter. The timing-jitter-free demultiplexing of the processor was demonstrated by an 80-km transmission experiment. Error-free bit error rate (BER) performance was achieved. Transmitted fourfold optical time-division multiplexing (OTDM) signals with a large timing jitter of about 16 ps for an OTDM signal interval of 25 ps were demultiplexed to 9.95-Gb/s signals without signal degradation.     

高速光时分复用系统的全光解复用技术

作为高速光信号处理应用的一个分支,全光解复用技术涉及到半导体非线性光学多方面的问题,是实现高速光时分复用（OTDM）系统的关键技术之一。文章对现有的OTDM系统的全光解复用技术进行了综述,较为详细地描述了两类主流技术的工作原理,对两者的优缺点做了剖析,介绍了潜在的基于更高速全光开关的解复用新技术,并探讨了全光解复用技术的演进思路。     

40-Gb/s OTDM to 4×10 Gb/s WDM conversion in monolithic InPMach-Zehnder interferometer module

Transformation of high bit-rate optical time-domain multiplexed (OTDM) signals into a multitude of lower bit-rate wavelength-division-multiplexed (WDM) channels is demonstrated by means of a single monolithically integrated indium phosphide Mach-Zehnder interferometer with semiconductor optical amplifiers in its arms. Full demultiplexing of 10-Gb/s OTDM signals into 4×10-Gb/s WDM channels is demonstrated. Bit-error-rate penalties are below 1.5 dB for polarization independent signal conversion throughout the 1.55-μm wavelength range     

Bismuth oxide nonlinear fibre-based 80 Gbit/s wavelength conversion and demultiplexing using cross-phase modulation and filtering scheme

Reported is the experimental demonstration of wavelength conversion and subsequent demultiplexing of an 80 Gbit/s OTDM signal using the cross-phase modulation and spectral filtering technique in short lengths of bismuth oxide-based nonlinear fibre with a nonlinearity of /spl gamma/=/spl sim/1100 W/sup -1/ /spl middot/ km/sup -1/. Error-free, overall operation is readily achieved over a wavelength tuning range of /spl sim/10 nm.     

All-optical time-division demultiplexing experiment withsimultaneous output of all constituent channels from 100 Gbit/s OTDMsignal

The successful demonstration of all-optical time-division demultiplexing is reported, wherein all 10 Gbit/s constituent channels are simultaneously demultiplexed with no error from a 10×10 Gbit/s OTDM signal. A multichannel demultiplexer based on cross phase modulation (XPM)-induced frequency shift in an optical fibre, called MOXIC, is used     

All-optical TDM data demultiplexing at 80 Gb/s with significant timing jitter tolerance using a fiber Bragg grating based rectangular pulse switching technology

We demonstrate the use of fiber Bragg grating based pulse-shaping technology to provide timing jitter tolerant data demultiplexing in an 80 Gb/s all-optical time division multiplexing (OTDM) system. Error-free demultiplexing operation is achieved with /spl sim/6 ps timing jitter tolerance using superstructured fiber Bragg grating based 1.7 ps soliton to 10 ps rectangular pulse conversion at the switching pulse input to a nonlinear optical loop mirror (NOLM) demultiplexer comprising highly nonlinear dispersion shifted fiber (HNLF). A 2-dB power-penalty improvement is obtained compared to demultiplexing without the pulse-shaping grating.     

In-band clock distribution concept for ultra-high bit rates OTDM system

A novel clock distribution concept based on inband phase-modulated pilot insertion is demonstrated.This method avoids the need for an ultrafast phase comparator and a phase-locked loop in the receiver.Experimental results show that the clock can be successfully extracted from 160Gbit/s optical time-division multiplexing (OTDM) data signal and employed for demultiplexing of 40Gbit/s tributaries.The in-band clock distribution introduces 1.5dB of power penalty with an error-free performance.     

Injection-locked Fabry-Pe/spl acute/rot laser with electronic feedback for clock recovery from high-speed OTDM signals

We demonstrate the use of an injection-locked Fabry-Pe/spl acute/rot laser diode with electronic feedback for base-rate clock recovery in N/spl times/10 Gb/s optical time-division-multiplexing (OTDM) systems. Injection-locking enhances the resonance frequency of the laser and the electrical feedback achieves strong resonance at the base-rate frequency of the injected data streams, enabling ultrastable electrical clock signal generation at the base rate of 10 GHz. Experimental demonstrations for clock recovery at 10 GHz from 40-Gb/s OTDM data streams and 4-1 demultiplexing of the data using the extracted clock after fiber transmission is presented. The timing jitter measured in the recovered electrical clock is less than 0.25 ps.     

Characterization of the Dynamic Absorption of Electroabsorption Modulators With Application to OTDM Demultiplexing

In this paper, a technique for characterizing the dynamic absorption of electroabsorption modulators (EAMs) under high-frequency sinusoidal modulation is described. By using an optical sampling oscilloscope (OSO), the nonlinear response of a modulator to 10- and 40-GHz modulation is accurately measured. The results for the dynamic absorption are used in a measurement-based model to calculate optical gating windows for the demultiplexing of a 160-Gb/s optical time-division multiplexed (OTDM) signal to its 10- and 40-Gb/s tributary signals. Good agreement is achieved between the calculated and measured gating windows.      

4×10Gb/s OTDM复用与解复用结构优化技术研究

基于40Gb/s OTDM复用结构,利用电吸收调制器(EAM)及时钟提取模块组成的解复用模型,实现了10GHz时钟分量的提取和信号的解复用.针对OTDM复用后信号的非等幅现象以及对应频谱中含有10GHz、20GHz等其他频谱分量的情况,进行了仿真分析及讨论.同时通过实验对不同的时钟提取与解复用结构提取出的时钟信号的质量进行了对比,优化了解复用结构,得到了抖动更小的帧时钟信号.     

40GHz窄时间窗口的实现及其在高速光时分复用系统中的应用

Optical Time Division Multiplexing (OT-DM) is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time window with low insert loss, low phase noise, low timing-jitter and high speed performance is essential for ultrahigh speed OTDM systems using phase and amplitude modulation formats. In this paper, we review three promising methods to obtain 40 GHz short time window including Electro-Absorption Modulator ( EAM ), Dual-Parallel Mach-Zehnder Modulator (DPMZM) and Fiber Loop-Polarization Modulator (FL-PolM). Subpicosecond short pulse source generation, optical time division demultiplexing and clock recovery are realized respectively by using the short time window based on the three methods. By using DPMZM based pulse source and EAM based Clock Recovery (CR) and demultiplexer, error free transmission of 640 Gbit/s (160 Gbaud/s Pol-Mux DQPSK) single channel signal over 400 km single mode fiber is proven to be experimentally successful.     

160 Gbit/s all-optical time-division demultiplexing utilisingmodified multiple-output OTDM demultiplexer (MOXIC)

The first successful demonstration of error-free simultaneous four-channel-output demultiplexing of 160 Gbit/s OTDM signals is reported. The key is a modification to the authors original multiple-output demultiplexer, MOXIC, that significantly increases the stability of its operation owing to improving on/off extinction ratios of demultiplexed signals     

Optical time-division multiplexing for very high bit-ratetransmission

Optical time-division multiplexing (OTDM) extends and expands the well-known techniques of electrical time-division multiplexing into the optical domain. In OTDM, optical data streams are constructed by time-multiplexing a number of lower-bit-rate optical streams. Opportunities for very high-speed transmission and switching are created by removing limitations set by the restricted bandwidth of electronics and by capitalizing on the inherent high-speed characteristics of optical devices. An overview of recent work in optical time-division multiplexing and demultiplexing is presented. Design considerations affecting system architecture are described. Emphasis on the factors that limit system performance, such as crosstalk between multiplexed channels. Examples of very high bit-rate optical time-division multiplexed system experiments using short pulses from mode-locked semiconductor lasers and high-speed Ti:LiNbO₃ waveguide switch/modulators are presented     

非线性光环镜及其在信息技术领域中的应用

扼要叙述了非线性光环镜的构成及工作原理 ,介绍了它在全光开关、全光解复用、信号再生、逻辑运算、信号格式变换及全光波长变换等信息技术领域的超快速响应中的应用。     

基于光滤波器的光时分复用光谱压缩技术实验

提出了解复用窗口匹配滤波器的概念,分析了利用光带通滤波器提高光时分复用(OTDM)频谱效率的光谱压缩技术。基于自制的40Gb/sOTDM复用器,采用电吸收调制器(EAM)及时钟提取模块组成的反馈环路解复用模块,以阵列波导光栅(AWG)作为电吸收采样窗口(EASW)的匹配滤波器对4×10Gbit/sOTDM信号进行光谱压缩,实现了无误码传输100km及传输后的解复用。实验结果表明,AWG的使用使得OTDM信号的频谱效率提高至4倍。