1.6 Tbit/s(40×40 Gbit/s)光通信传输系统

在国家自然科学基金网(NSFCNet)上已实现由400 km×10 Gbit/s传输链路直接升级的一路400 km×40 Gbit/s光传输实验的基础上,采用自行研制的40×40 Gbit/s载波抑制归零(CS-RZ)码多波长光发送源,进行了160 km的1.6 Tbit/s(40×40 Gbit/s)波分复用(WDM)光传输实验。实验结果表明,对于常规中短距离10 Gbit/s传输链路可以直接升级至40 Gbit/s。但是由于40 Gbit/s传输系统的色散容限小于60 ps/nm,而且传输光纤与色散补偿模块的色散斜率不匹配,要实现40通道40 Gbit/s的传输,必须对40个信道分别进行精细的色散补偿。这也说明,对于宽带的40 Gbit/s多波长系统,有必要优化设计或更新传输链路。     

基于10 Gb/s传输链路的40 Gb/s光传输实验研究

基于中国自然科学基金网(NSFCNet)的400 km×10 Gb/s光传输链路实现了40 Gb/s光传输,没有出现误码率(BER)平台,说明在常规的中短距离10 Gb/s系统可以直接升级至40 Gb/s系统,而不需要升级传输链路。但是,由于相对10 Gb/s系统而言40 Gb/s系统的色散容限非常小,在升级时必须精确补偿原有链路的色散,在接收机前一般需要加可调色散补偿单元。同时,还分析了光纤注入功率对系统性能的影响,结果表明在设计这种由10 Gb/s向40 Gb/s升级的系统时,不仅要考虑信号带宽增加带来信噪比要求的提高,而且必须充分考虑光纤非线性的影响。     

An optical bit-rate flexible transmission system with 5-Tb/s-kmcapacity employing multiple in-line erbium-doped fiber amplifiers

An optical bit-rate flexible transmission system using erbium-doped fiber amplifiers (EDFAs) is proposed, and the system design is discussed. An optical bit-rate flexible system using multiple in-line erbium-doped fiber amplifiers has produced a regenerative repeater spacing of 505 km at 10 Gb/s and 523 km at 5 Gb/s for direct-detection systems. This system proves that an optical bit-rate flexible system with a transmission capacity of 5.05 Tb/s-km can be feasibly constructed. System capacity is clarified both theoretically and experimentally. The power penalties involved are discussed. The related optical and electrical circuits proved operational above 10 Gb/s. The 523 km at 5 Gb/s and 505 km at 10 Gb/s transmission experiments successfully demonstrated that EDFAs effectively enhance a system's transmission capacity     

High-Performance and Low-Cost 40-Gb/s CWDM Optical Modules

High-performance and low-cost 40-Gb/s optical modules using four different wavelength uncooled 10-Gb/s distributed-feedback (DFB) lasers are proposed and demonstrated. The 40-Gb/s optical module was integrated with coarse wavelength division multiplexing (CWDM) thin-film filters which enabled four 10-Gb/s transmission channels output through a single fiber. The 10-Gb/s DFB laser was packaged by commercialized low-cost coaxial TO-Can technology. The results of the 40-Gb/s optical module showed that the output optical power was above ${-}1$ dBm per channel and the system power budget was 12 dB. The transmission distance with a single-mode fiber reached more than 30 km at a bit-error-rate of $10^{{-}9}$. Compared with conventional 40-Gb/s optical modules, the module is easy to fabricate and is low cost. This proposed high-performance 40-Gb/s CWDM optical module demonstrates not only the feasibility of a 30 km transmission, but also shows the low-cost possibility of ensuring the application of WDM-passive optical network fiber-to-the-home systems.      

High performance 10 Gbit/s pin-FET optical receiver

An optical receiver suitable for a 10 Gbit/s direct detection optical transmission system is described. It uses a pin diode, commercial GaAs MESFETs and hybrid construction techniques on a coplanar substrate. The measured sensitivity of the receiver is -20.4 dBm, which is the best reported sensitivity at 10 Gbit/s for a pin-FET optical receiver to date.<>     

64-Gb/s highly reliable network switch (RHiNET-2/SW) using paralleloptical interconnection

RHiNET-2/SW is a network switch that enables high-performance optical network based parallel computing system in a distributed environment. The switch used in such a computing system must provide high-speed, low-latency packet switching with high reliability. Our switch allows high-speed 8-Gb/s/port optical data transmission over a distance of up to 100 m, and the aggregate throughput is 64 Gb/s. In RHiNET-2/SW, eight pairs of 800-Mb/s×12-channel optical interconnection modules and a one-chip CMOS ASIC switch LSI (a 784-pin BGA package) are mounted on a single compact board. To enable high-performance parallel computing, this switch must provide high-speed, highly reliable node-to-node data transmission. To evaluate the reliability of the switch, we measured the bit error rate (BER) and skew between the data channels. The BER of the signal transmission through one I/O port was better than 10^-11 at a data rate of 800 Mb/s ×10 b with a large timing-budget margin (870 ps) and skew of less than 140 ps. This shows that RHiNET-2/SW can provide high-throughput, highly reliable optical data transmission between the nodes of a network-based parallel computing system     

Transmission performance analysis of 8/spl times/10 Gb/s WDM signals using cascaded SOAs due to signal wavelength displacement

We have analyzed the transmission performance of 8/spl times/10 Gb/s wavelength division multiplexing (WDM) signals due to crosstalk in cascaded conventional semiconductor optical amplifiers (SOAs). Using two different methods, the crosstalk over the whole gain bandwidth in SOAs is calculated to be 2-5 dB lower for the positive detuning. Then, transmission performance of 8/spl times/10 Gb/s WDM signals up to 6/spl times/40 km span in terms of receiver sensitivity is estimated over various transmission distances using cascaded SOAs for the positive signal wavelength displacement of 30, 40, and 50 nm. Especially for 50 nm detuning, transmission performances with and without using a reservoir channel are similar to each other. Our results suggest that SOAs can be used as an optical amplifier for displacement larger than 50 nm without using the reservoir channel.     

10-Gb/s error-free transmission under optical reflection using isolator-free 1.3- /spl mu/m InP-based vertical-cavity surface-emitting lasers

Error-free transmission through 10-km single-mode fiber at 10 Gb/s under -13-dB optical reflections has been demonstrated for the first time using a directly modulated 1.3-/spl mu/m InP-based VCSEL without any optical isolator. The 13-GHz relaxation oscillation frequency and stable polarization suppresses relative intensity noise degradation under optical reflection. Only 1-dB error-free power penalty has been observed with optical reflection set with the worst polarization direction.     

Beyond 240 Gb/s per Wavelength Optical Transmission Using Coded Hybrid Subcarrier/Amplitude/Phase/Polarization Modulation

In this letter, we propose a low-density parity-check coded hybrid subcarrier/amplitude/phase/polarization (H-SAPP) modulation scheme suitable to achieve a 240-Gb/s single-channel transmission rate over optical channels. The proposed scheme doubles the aggregate transmission rate achievable by eight-quadrature amplitude modulation while providing 2-dB optical signal-to-noise ratio performance improvement at a bit-error-ratio (BER) of $10^{-6}$ . Moreover, H-SAPP can increase the aggregate rate of the hybrid amplitude/phase/polarization scheme while maintaining the BER performance intact.      

准相干技术在C波段25 Gbit/s光模块中的研究与应用

针对传统C波段高速光模块传输距离过短的问题,文章对一种准相干接收技术进行了研究,结合现有25 Gbit/s光模块进行了实验,并讨论了准相干接收技术的应用方案.研究发现,准相干接收技术以外差相干检测技术为基础,具有结构简单和成本低等优点,在不使用额外的电或光色散补偿技术的前提下,准相干接收机也能有效减少色散对高速光模块传...     

Over 300 km CPFSK transmission experiment using 67 photon/bit sensitivity receiver at 2.5 Gbit/s

A nonrepeated fibre transmission experiment over 308 km of conventional optical fibre is reported at 2.5 Gbit/s in a CPFSK heterodyne detection system. The system has a sensitivity of -46.7 dBm or 67 photons/bit at 10/sup -9/ BER and has the maximum allowable attenuation of 55.1 dB without an optical amplifier.<>     

Demonstration of 20 Gbit/s subcarrier multiplexed transmissionsystem

A 20 Gbit/s subcarrier multiplexed (SCM) optical transmission system is presented. To date, this represents the highest aggregate bit rate SCM transmission that has been demonstrated. Results show that the bit error rate (BER) is less than 10^-12 for a link loss of 29.5 dB, which corresponds to 118 km single mode fibre (SMF). Furthermore, excellent performance is demonstrated after transmission over 82 km of dispersion compensated SMF. Results suggest that the system can support transmission over multiple spans of optical fibre     

Eye-opening improved electroabsorption modulator/DFB laser diodewith optimized thickness of the separate-confinement heterostructurelayers

The separate-confinement heterostructure (SCH) of an electroabsorption modulator integrated with a distributed feedback laser diode (EAM-LD) was optimized to obtain a clear optical waveform (eye opening) without penalty of chirp characteristics. The electric field applied to the multiple-quantum-well (MQW) structure was controlled by employing the proper thickness of undoped SCH layers to attain gentle absorption characteristics of the EAM at the optical mark level. As a result, the eye opening of the modulated emission at 10 Gb/s was improved and the intersymbol interference was reduced. No severe drawback on chirp characteristics was found in an α-parameter measurement. EAM-LD's with the optimized SCH structure exhibited good transmission characteristics of power penalties under 1.5 dB at 10 Gb/s, and the reliability of 10 Gb/s transmission characteristics was also confirmed. We have also investigated how the optical waveform after transmission was affected by the dependence of the α-parameter on bias voltage. Measurement and numerical calculation of the optical waveform after transmission showed that the optical waveform was severely affected by the α-parameters at deep reverse voltages     

Direct current to 34.1-Gb/s, 19-Gb/s/cm/sup 3/ low-jitter parallel optical interconnecting module for high-speed memory test systems

A protocol-free parallel optical interconnecting module is introduced as a solution to solve memory test system transmission bottlenecks. The optical transmission system flexibly suited for a memory test system is reviewed and discussed. A parallel optical module capable of transmitting from dc to 34.1Gb/s (4.267 Gb/s /spl times/8 ch) has been developed. A data transmission throughput density per unit volume of 19 Gb/s/cm/sup 3/ is achieved. A random jitter of less than 3-ps root-mean-square is also achieved. Furthermore, high-density optical connector, high-density optical fiber cable, fiber guides, and cable management/reinforcement members suited for mechanical requirements of the memory test system have been developed.     

Design of a MoOx/Au/MoOx transparent electrode for high-performance OLEDs

A MoO_x(top)/Au/MoO_x(bottom) multilayer was systematically designed for transparent electrodes in green OLEDs in terms of optical transmission and series resistance of the device. The enhancement in optical transmission of MoO_x/Au/MoO_x (MAM) structures is a result of a series of events, including the optical interference within the multilayers and the interaction of light with surface plasmon polaritons in the metal layer. For the maximum transmission, the optical interference occurring within the multilayers was simulated using a transfer matrix model to determine the optimum thickness of MoO_x layers, and then the thickness of the Au interlayer was experimentally optimized for extraordinary optical transmission. In addition, the series resistance added by the top MoO_x was characterized to confirm its negligible impact on the performance of the device. The optimum MoO_x (40 nm)/Au (10 nm)/MoO_x (40 nm) structure showed much higher transmission in the green-red region and lower sheet resistance than indium tin oxide (ITO). We have fabricated MAM-based OLEDs the driving voltage of which was significantly reduced to ∼5.5 V at a current density of 20 mA/cm², and the current efficiency (11.46 Cd/A) was higher than that (10.91 Cd/A) of ITO-based OLEDs, demonstrating that the MAM electrode is a potential replacement for ITO in optical devices.     

Very high speed intra-office optical link experiments for 0.4- and 1.6-Gbit/s trunk lines

Very high speed optical links are studied. Applicable areas for systems using light-emitting diodes (LED'S) or laser diodes (LD's) with short transmission length are clarified. A new type differential mode inversion (DMI) decoder is proposed and it is shown that the DMI code is suitable as the line code for very high speed intra-office optical links. By using DMI code. a 400-Mbit/s information rate optical transmission experiment employing a 1.3-μm InGaAsP LED and a 0.5-km graded-index multimode optical fiber (GIF) as well as a 1.6-Gbit/s information rate optical transmission experiment using a 1.3-μm InGaAsP/InP Fabry-Perot-type LD and a 10-km single-mode optical fiber (SMF) are carried out. These results show that the feasibility of a 400-Mbit/s intra-office optical link using the LED and GIF, as well as a 1.6-Gbit/s intra-office optical link using the LD and SMF, are confirmed and this optical transmission technology has high-speed performance up to 3.2 Gbit/s.     

Distance limits of 10 to 20 Gbit/s FSK transmission on standardfibre

A simple analysis is performed on an FSK transmission system using a high FM efficiency, high bandwidth DFB laser as a simple DFB transmitter and an FM/AM converter as an optical signal processor. It shows that optimum optical processing pushes the transmission limits to 150 km at 10 Gbit/s and to 40 km at 20 Gbit/s     

Ultralow error rate and dispersion-free transmission of 2.5 Gbit/s SONET for gigabit networks

It is demonstrated that for an NRZ modulated 1310 nm optical transmitter, dispersion-free transmission can be achieved up to approximately 250 km using dispersion-shifted singlemode fibre (DS-SMF) and optical pulse compression. This result implies that DS-SMFs have a potential advantage over standard SMFs for dual-window (1310/1550 nm) multigigabit per second transmission systems. Results on the long-term error performance of experimental prototype 2.5 Gbit/s SONET optical transmission systems are presented with measured error rates smaller than 10/sup -15/.<>     

具有连续自动温度补偿功能的10Gb/s光收发模块

设计并制作了一种10Gb/s光收发模块,在宽温度范围内能够保持稳定的光功率和消光比。基于背电流和光功率的换算比例,计算其偏置电流修正值和调制电流修正值,实现了光模块运行过程中激光器的工作参数可自动连续调节。通过高速电路信号仿真设计,解决了信号完整性、串扰和电磁兼容等问题。光模块收发通道可以独立工作,传输速率可达10Gb/s,实现了光模块高速率、高稳定性以及小体积设计,为甚短距离高速数据传输和处理提供了高可靠性的数据链接。     

Pseudomorphic 2DEG FET IC's for 10 Gb/s optical communicationsystems with external optical modulation

An optical modulator driver IC and a preamplifier IC for 10 Gb/s optical communication systems are developed using AlGaAs/InGaAs/GaAs pseudomorphic two-dimensional electron gas (2DEG) FETs with a gate length of 0.35 μm. The optical modulator driver IC operates at a data rate up to 10 Gb/s with an output voltage swing of more than 4 V_p-p . The bandwidth for the amplifier IC is 13.0 GHZ with ab 47 dB-Ω transimpedance gain. In addition, optical transmission experiments with external optical modulation using these ICs have successfully been carried out at 10 Gb/s