112 Gbit/s信号混传多种速率信号的非线性效应影响

主要研究在波长间隔50GHz的密集波分复用系统中,112Gbit/s偏分复用差分四相移键控信号在不同速率的相邻信道影响下经过长距离传输后的非线性容忍度。实验结果表明,112Gbit/s信号结合43Gbit/s信号或者10Gbit/s信号传输时系统得到较好的非线性容忍度,验证了在严重的非线性效应存在的情况下同步传输系统的可行性。     

Simultaneous demodulation and slow light of differential phase-shift keying signals using stimulated-Brillouin-scattering-based optical filtering in fiber

For the first time to our knowledge, we demonstrate simultaneous demodulation and slow-light delay of differential phase-shift keying (DPSK) signals at flexible bit rates using the stimulated-Brillouin-scattering-based optical filtering effect in optical fiber. Both 10 and 2.5 Gbit/s DPSK signals have been demodulated and delayed with excellent performances. In the case of the 10 Gbit/s DPSK signal, after demodulation the tunable delay range with error-free operation is about 50 ps, which we believe is the best result obtained for 10 Gbit/s slow-light demonstrations. For the 2.5 Gbit/s DPSK signal, the optimal sensitivity after demodulation is -36.5 dBm, which is comparable with the back-to-back sensitivity of a 2.5 Gbit/s nonreturn-to-zero signal.     

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SOA器件的色散补偿系统

基于半导体光放大器非线性效应提出一种连续可调谐的色度色散补偿方法.利用SOA的交叉相位调制效应,对10 Gbit/s和 40 Gbit/s RZ码系统的补偿效果和补偿范围进行了仿真分析.分析结果表明,该方法在10 Gbit/s传输系统中,可以实现补偿范围为400 ps/nm的正负色散.在40 Gbit/s传输系统中,可以实现补偿范围为40 ps/nm的正负色散.在理论分析基础上,进行了10 Gbit/s传输系统下连续动态色度色散测补偿实验.实验结果表明,该方法实现了-40～60 ps/nm范围内色度色散的连续可调谐补偿.     

Simultaneous demultiplexing and clock recovery using a single electroabsorption modulator in a novel bi-directional configuration

A single electroabsorption modulator was used to demultiplex a 10 Gbit/s channel from a 40 Gbit/s OTDM data stream, whilst simultaneously recovering the 10 GHz electrical clock. This was achieved using a new bi-directional operation of the EA modulator, combined with a simple phase-locked loop feedback circuit. Excellent system performance was achieved, indicating that operation up to and beyond 100 Gbit/s is possible using current technology.     

Spectrally efficient slow light using multilevel phase-modulated formats

A phase-preserving and spectrally efficient slow-light scheme has been proposed and demonstrated by utilizing advanced multilevel phase-modulated formats. A 60 ps symbol delay with error-free demodulation of both I and Q channels for 10 Gbit/s return-to-zero differential-quadrature-phase-shift-keyed (DQPSK) signals via a broadband stimulated Brillouin scattering-based slow-light medium is achieved experimentally. Simulation results on 20 Gbit/s DQPSK and 30 Gbit/s D8PSK propose to transmit very high spectrally efficient multilevel formats through a bandwidth-limited slow-light element.     

10 Gbit/s Silicon modulator and germanium detector chip-to-chip optical link

Experimental results of a high-speed silicon optical modulator based on carrier depletion in a pipin diode and Germanium photodetectors are presented. 10 Gbit/s data transmission is obtained for both optoelectronic devices, with for the optical modulator an extinction ratio (ER) higher than 8 dB and insertion loss (IL) lower than 6 dB and for Ge photodetector, a zero-bias operating at 10 Gbit/s. Finally, a 10 Gbit/s optical link combining Si modulator and Ge photodetector is demonstrated.     

Interchannel nonlinear transmission penalties in polarization-multiplexed 2 x 10 Gbit/s differential phase-shift keying transmission

We discuss the performance of a multichannel 2 x 10 Gbit/s polarization-multiplexed differential phase-shift keying transmission system. Through simulations and transmission experiments we find that, despite the constant power envelope of non-return-to-zero phase-shift keying modulation formats, polarization multiplexing strongly reduces the nonlinear tolerance and transmission performance at a 2 x 10 Gbit/s line rate with multichannel transmission. This results in a 10 dB power penalty when comparing single- and nine-channel transmission. Additionally, multichannel impairments in differential phase-shift keying and on-off keying are compared for 2 x 10 Gbit/s polarization-multiplexed transmission.     

二阶偏振模色散对高速高斯光脉冲在单模光纤中传输的影响

研究二阶偏振模色散（PMD）对高斯光脉冲在单模光纤中传输产生的影响，给出输出光脉冲的时域表达式。分析表明，输出光脉冲在每个基本偏振态上仍保持高斯形状，但其频率啁啾及脉宽等特性都已改变，文中对这些变化与二阶偏振模色散之间的关系进行了讨论。通过比较10Gb/s和40Gb/s的光传输系统中二阶偏振模色散的影响，可以发现，若规定脉冲展宽不能超过脉宽的十分之一，40Gb/s系统所能容忍的二阶偏振模色散极限值比10Gb/s系统小一个数量级。     

Recent Progress of Wavelength Division Multiplexing Technology In Tera-bit/s Transoceanic Undersea Cable Systems

Transmission capacity for optical undersea cable systems is growing remarkably and a more than 500-fold increase has been achieved for commercial systems over the past 10 years. The first optical fiber cable in the Pacific Ocean went into service in 1989 and has a capacity of 280 Mbit/s per fiber pair. The emergence of an Erbium-doped fiber amplifier paved the way for a drastic capacity increase for these cables, and large capacity optical amplifier undersea cable systems with 5 Gbit/s per fiber pair were constructed worldwide in 1995-1996. Recent 10 Gbit/s-based wavelength division multiplexing (WDM) technologies together with new fibers and new amplifiers have allowed a further increase in capacity up to 160 Gbit/s, and these WDM systems will begin commercial service in both the Pacific Ocean and the Atlantic Ocean in 2000. Research interest is now being directed towards the development of undersea cable systems with a transmission capacity of 1 Tera-bit/s or more. This paper reviews the key technologies for next generation 160 Gbit/s optical undersea cable systems and recent progress towards Tera-bit/s systems. Dispersion managed soliton transmission for future higher bit rate WDM is also discussed.     

Directly modulated DBR lasers for long-haul transmission at 1.7 Gbit/s

We demonstrate 1.7 Gbit/s transmission through 257 km of conventional fiber using directly modulated distributed-Bragg reflector (DBR) lasers and fiber amplifiers. This experiment resulted in a record bit rate distance product of 437 km Gb/s for direct modulation at rates between 1 and 3 Gbit/s. This paper has been accepted for presentation at OFC '92.     

具有旋转连接功能的双层光互连网络设计

在设计的双层光互连网络中,上层网络是星型连接,依靠数字路由结点进行通信.单通道最大传输速率为1.4 Gbps,数字路由结点吞吐率大于10 Gbps,底层为网络接口卡和结点机连成的环形网,峰值传输速率为1.056 Gbps.在底层网络中个别结点机与传感器之间配置有光纤旋转连接器,可传输动态数据.经计算,环网内最大通信延迟时间小于5.292 μs,互连网络的平均通信延迟时间为11.03 μs,环形网络的最大数据传输带宽为50 Mbit/s.     

Gain Controlling of Erbium-Doped Fiber Amplifier by Samarium Doped Inner-Cladding in the 1.5µm Region

In this work, WDM transmission with 40-Gbit/s per channel bit rate has been experimentally demonstrated over a 500-km link. Different chromatic dispersion conditions have been managed and in-line all-optical wavelength conversion has been carried out with a periodical poled lithium niobate (PPLN) device in a polarization-independent scheme. The link was obtained by connecting the fibers contained in an installed cable between Roma and Pomezia (25 km), encompassing single-mode (G.652) and high-end (G.655, non-zero dispersion with a particular value and flat curve for chromatic dispersion) fibers. Some 40 Gb/s channels were propagated in the link 500 km long and one channel was dropped from the link after 300-km propagation, wavelength converted, and added to the other channels for the next 200 km. The electrical data interfaces exploited a 4 × 10 Gbit/s to 1 × 40 Gbit/s MUX at the transmitter, along with a 1 × 40 Gbit/s to 4 × 10 Gbit/s DMUX at the receiver. Successful transmission of 4 channels, 200-GHz spaced, has been achieved over 500 km along both G.652 and G.655 links. No evidence of penalty comparing converted and unconverted channels has been reported. Transmission experiments of 8 × 40 Gbit/s, with 100 GHz frequency spacing, are also reported. No significant degradation has been observed in the case of the G.652 link.     

In-Field n × 40 Gb/s Transmission Experiments with In-Line All-Optical Wavelength Conversion

In this work, WDM transmission with 40-Gbit/s per channel bit rate has been experimentally demonstrated over a 500-km link. Different chromatic dispersion conditions have been managed and in-line all-optical wavelength conversion has been carried out with a periodical poled lithium niobate (PPLN) device in a polarization-independent scheme. The link was obtained by connecting the fibers contained in an installed cable between Roma and Pomezia (25 km), encompassing single-mode (G.652) and high-end (G.655, non-zero dispersion with a particular value and flat curve for chromatic dispersion) fibers. Some 40 Gb/s channels were propagated in the link 500 km long and one channel was dropped from the link after 300-km propagation, wavelength converted, and added to the other channels for the next 200 km. The electrical data interfaces exploited a 4 × 10 Gbit/s to 1 × 40 Gbit/s MUX at the transmitter, along with a 1 × 40 Gbit/s to 4 × 10 Gbit/s DMUX at the receiver. Successful transmission of 4 channels, 200-GHz spaced, has been achieved over 500 km along both G.652 and G.655 links. No evidence of penalty comparing converted and unconverted channels has been reported. Transmission experiments of 8 × 40 Gbit/s, with 100 GHz frequency spacing, are also reported. No significant degradation has been observed in the case of the G.652 link.     

Experimental Study on Time-Spread/Wavelength-Hop Optical Code Division Multiplexing with Dispersion-Compensating En/Decoder

10Gbit/s time-spread/wavelength-hop optical code generation and decoding are performed by dispersion-compensating fiber Bragg grating (FBG) en/decoder pair. Error-free 10km single mode fiber (SMF) transmission of 10Gbit/s optical code division multiplexing (OCDM) has been experimentally demonstrated.     

740 Gbit/s (37 x 20 Gbit/s) DWDM Transmission Experiment Using Er3+-Doped Tellurite Fiber Amplifiers and Distributed Raman Amplification

We demonstrate 740 Gbit/s (37 × 20 Gbit/s) DWDM recirculating transmission experiment with 59 nm continuous bandwidth over 300 km by employing Er3+-doped tellurite fiber amplifiers. The use of Raman amplification is effective to increase the transmission bandwidth.     

Directly modulated DBR lasers for long-haul transmission at 1.7 Gbit/s

Abstract

We demonstrate 1.7 Gbit/s transmission through 257 km of conventional fiber using directly modulated distributed-Bragg reflector (DBR) lasers and fiber amplifiers. This experiment resulted in a record bit rate distance product of 437 km Gb/s for direct modulation at rates between 1 and 3 Gbit/s. This paper has been accepted for presentation at OFC '92.     

10-Gbit/s Serial Optical Interconnection for an ATM Switch

Serial optical interconnection is proposed for connections in a Torus asynchronous transfer mode switch. A cross-point switch was developed that operates at a bit rate of 20 Gbit/s. The switching operation was successfully performed using cascaded cross-point switches through an optical interconnection configuration consisting of commercial optoelectronics devices. The measured switching rate was 10 Gbit/s, and it was limited by the responses of the optoelectronics devices.     

Experimental observation of a 1.5 microm band wavelength conversion and logic NOT gate at 40 Gbit/s based on sum-frequency generation

We have experimentally verified a new idea for 40 Gbit/s wavelength conversion within the 1.5 microm band based on sum-frequency generation (SFG) in a periodically poled LiNbO3 waveguide. The spectrum and the temporal waveform of the output pump reveal that the input cw pump is converted to an optical pulse during SFG. Not only wavelength conversion but also a logic NOT gate at 40 Gbit/s are experimentally observed.     

Study of dual-directional high rate secure communication systems using chaotic multiple-quantum-well lasers

A scheme of synchronized injection multi-quantum-well (MQW) laser system using optical coupling-feedback is presented for performing chaotic dual-directional secure communication. The performance characterization of chaos masking is investigated theoretically, the equation of synchronization demodulation is deduced and its root is also given. Chaos masking encoding with a rate of 5\,Gbit/s and a modulation frequency of 1\,GHz, chaos modulation with a rate of 0.2\,Gbit/s and a modulation frequency of 0.2\,GHz and chaos shifting key with a rate of 0.2\,Gbit/s are numerically simulated, separately. The ratio of the signal to the absolute synchronous error and the time for achieving synchronous demodulation are analysed in detail. The results illustrate that the system has stronger privacy and good performances so that it can be applied in chaotic dual-directional high rate secure communications.