密集波分复用系统中波长控制技术研究

本文利用半导体激光器的热阻模型,研究分析了密集波分复用系统中光源的波长控制技术。利用本文的理论指导设计的特定波长的光源已经应用于武汉邮电科学研究院研制的济南—青岛８×２．５Ｇｂｉｔ／ｓ密集波分复用实验工程。     

A Fast Optical Wavelength-Tunable Transmitter With a Linear Thermoelectric Cooler Driver

This letter demonstrates a fast optical wavelength-tunable transmitter based on a sampled grating distributed Bragg reflector (SG-DBR) laser. A high-precision clock distributing circuit has been introduced into the transmitter to guarantee the switching synchronization for driving currents to different tuning sections of the SG-DBR laser. To achieve fast and accurate wavelength switching, a linear thermoelectric cooler driver board has been applied as a part of the transmitter to stabilize the temperature of the SG-DBR laser. Experiments have been performed to show the wavelength switching characteristics of the optical transmitter.      

Fast wavelength detection technique for multi-wavelength photonic packet networks

A wavelength detection technique for the control of transmitter wavelengths in WDM/FDM optical packet networks is demonstrated. The wavelength of a transmitter can be determined within a single packet duration (1.6 mu s). The authors demonstrate optical frequency detection to an accuracy of +or-75 MHz over a capture range of 6 GHz.<>     

Simultaneous fast wavelength switching and intensity modulationusing a tunable DBR laser

The use of a three-section distributed Bragg reflector (DBR) laser to switch wavelengths rapidly and simultaneously transmit data by intensity modulation is discussed. This combination simulates the operation of a tunable transmitter in a multiwavelength packet switch. In this type of switch, each output port is tuned to receive data on a unique, fixed wavelength; packets are routed from input ports to the appropriate output ports by wavelength addressing. In each transmission cycle, the input port transmitter tunes to the wavelength associated with the intended output port and subsequently broadcasts the data packet. Limitations on various system parameters, such as the number of allowed channels, the wavelength switching times, and packet lengths (residency times), as determined by thermally-induced wavelength drifts are also discussed. The advantages of using a single device for both fast wavelength switching and direct data modulation are significant: the elimination of external modulators improves both the simplicity of the implementation and the available power budget     

2.5 Gbit/s光发射模块的中心频率稳定性研究

波分复用的系统光源中心频率的稳定技术是该系统的关键技术之一。本文研究了高速率（以２．５Ｇｈｉｔ／ｓ速率为例）速分复用系统中光发射模块中心频率的稳定技术一温度反馈稳频技术。根据温度反馈稳频技术原理,作者设计并调试了高精度自动控制模块。该控温模块通过控制２．５Ｇｂｉｔ／ｓ光发射模块中激光器管芯温度来稳定其中心频率,为波分复用系统的应用提供了具备稳定中心频率特性的光源。     

Interference in CPFSK optical crossconnect systems with noncoherentdetection

In optical crossconnect applications, as the wavelength of a transmitter laser is switched from one channel to another, it may momentarily coincide with wavelengths being used by other transmitter lasers. The resultant interference is assessed experimentally for CPFSK systems with noncoherent detection based on a Fabry-Perot optical filter. It is shown that wavelength switching causes a significant degradation in the bit error ratio performance when direct frequency modulation is used. The influence of the relative states of polarisation of the modulated and switched signals on the switching induced interference is also examined     

A 10-Gb/s Monolithically Integrated Filterless InGaAsP/InP Widely Tunable Wavelength Converter With Conversion Gain

In this paper, we present the details of a monolithically integrated filterless wavelength converter based on photocurrent-driven technology. The device consists of an integrated tunable laser transmitter and an optical receiver. The transmitter includes a sampled-grating distributed-Bragg-reflector laser, an electroabsorption modulator, and a semiconductor optical amplifier. The optical receiver employs two semiconductor optical amplifiers and a quantum-well p-i-n photodetector. The wavelength converter is characterized at 10 Gb/s over a variety of bias conditions at various input-power levels in various digital-system experiments. Bit-error-rate measurements at 10 Gb/s over an output tuning range of 32 nm between 1531 and 1563 nm show power penalties less than 1 dB. Similar experiments over an input wavelength range of 25 nm from 1535 to 1560 nm show a power penalty less than 2.5 dB. For a wavelength conversion from 1548 nm to a range of output wavelengths between 1531 and 1563 nm, the facet-to-facet gain ranges from 9 to 13 dB, neglecting fiber coupling losses.     

Cost-effective wavelength selectable light source using DFB fibrelaser array

A cost-effective wavelength selectable light source comprising a distributed feedback (DFB) fibre laser array is proposed. A large number of wavelengths can be selected via optical space switches using only one shared pump laser. The structure is a good candidate for use as a wavelength selectable backup transmitter for wavelength division multiplexed (WDM) systems     

基于FPGA的DWDM光源控制系统

设计了一种新型的DWDM光源控制系统,该系统采用MCU FPGA技术,可以同时对多个DWDM光源通道进行温度、波长和功率的检测控制,并且通过GPIB总线实现了PC机的远程控制.数字控制系统中FPGA技术的采用降低了系统的复杂性,提高了系统的可靠性和灵活性.在温度控制模块中,采用分阶段模糊控制的方法提高了系统的响应速度和控制精度.在LD控制模块中采用新型的波长锁定技术实现波长的高精度控制,同时采用软启动、限幅电路和短路开关等措施进行LD的浪涌保护.实验研究表明,该系统的温度和波长控制效果较好,而且能抑制因老化引起的波长漂移.     

高速光发射模块温度反馈稳频技术的理论分析

波分复用系统光源中心频率的稳定技术是该系统的关键技术之一。文中从理论上研究了高速率 (以 2 5Gbit/s速率为例 )波分复用系统中光发射模块中心频率的稳定技术温度反馈稳频技术。     

Selected area growth integrated wavelength converter based on PD-EAM optical logic gate

A selected area growth wavelength converter based on a PD-EAM optical logic gate for WDM application is presented, integrating an EML transmitter and a SOA-PD receiver. The design, fabrication, and DC characters were analyzed. A 2 Gb/s NRZ signal based on the C-band wavelength converted to 1555 nm with the highest extinction ratio of 7 dB was achieved and wavelength converted eye diagrams with eyes opened were presented.     

MOSAIC: a multiwavelength optical subcarrier multiplexed controllednetwork

The experimental demonstration of MOSAIC, a reconfigurable WDM add/drop network with subcarrier multiplexed control, is presented. The MOSAIC network implements the optical layer protocol to support bit-rate transparent multichannel lightpaths. Two types of add/drop multiplexers are implemented and combined in a three-node experiment. Multihop lightpaths are established giving an end-to-end bit error rate of better than 10^-9 at 1.2 Gbps. The reconfigurable add/drop multiplexer is based on a novel dilated 2×2 acoustooptic filter switch crossconnect and an analog optoelectronic crossconnect that drives a ten-wavelength laser array transmitter up to 2.5 Gbps per wavelength. The fixed wavelength add/drop multiplexer utilizes a fast digitally tunable laser transmitter. Both add/drop multiplexers support bit-rate transparent 2R optoelectronic regeneration as well as wavelength translation. Subcarrier multiplexing on each wavelength is used to support channel state monitoring and channel equalization as well as transmission of digital network control information. Systems experiments demonstrate cascaded 2R optoelectronic regeneration with wavelength translation and cascaded multichannel optical switching with up to seven hops. It is shown that combining cascaded 2R optoelectronic regeneration with cascaded multichannel optical switching can be used to balance jitter accumulation and amplified spontaneous emission generated amplitude noise to yield high signal-to-noise ratio for lightpaths     

Scheduling transmissions in WDM broadcast-and-select networks

Considers a broadcast-and-select, wavelength division multiplexed (WDM), optical communication network that is packet switched and time slotted. The amount of time it takes transmitters and receivers to tune from one wavelength to another is assumed to be T slots. The authors consider all-to-all transmission schedules, which are defined to be ones that schedule a packet transmission between each input-output pair. They present upper and lower bounds for the minimum length of such schedules. In particular, if each of N inputs has a tunable transmitter and each of N outputs has a tunable receiver then the minimum length is between (N+o(N))(√T+1) and ((N+o(N))√T. This provides some insight into the relationship between packet delay and T. The authors also consider schedules that do not allow packet transmissions while a transmitter or receiver is tuning from one wavelength to another     

A wavelength-tunable optical transmitter using semiconductor optical amplifiers and an optical tunable filter for metro/access DWDM applications

This paper proposes and demonstrates a widely tunable and precisely controllable optical transmitter that uses semiconductor optical amplifiers (SOAs) and an optical tunable filter (OTF) for metro/access dense-wavelength-division-multiplexing (DWDM) systems/networks. The transmitter consists of a fiber-ring-laser section based on SOA(s) and an OTF and a modulation section based on an SOA. First, the requirements imposed on the components intended for the fiber-ring laser are clarified through approximate analyses and basic experiments. To obtain low-noise characteristics, the lower limit of effective OTF bandwidth is investigated by considering the SOA carrier lifetime. For obtaining wavelength precision, the upper limit of the effective OTF bandwidth is derived by considering the SOA ripple effect. Next, the proposed transmitter is demonstrated, where all SOAs are integrated into one planar lightwave circuit (PLC) platform using spot-size converting technology. By designing the fiber-ring-laser section according to the clarified requirements, a wavelength control precision of /spl plusmn/1.75GHz is achieved while realizing the required relative intensity noise (RIN) from 1540 to 1560 nm. Finally, it is demonstrated that the transmitter can handle signals at up to 1.25 Gb/s.     

Widely tunable 10 Gbit/s separate absorption and modulation Mach-Zehnder wavelength converter

A fully monolithic separate absorption and modulation region wavelength converter requiring no bias tees has been fabricated. The device consists of a transmitter comprising a sampled-grating DBR laser and series-push-pull Mach-Zehnder modulator, and a receiver composed of a linear semiconductor optical amplifier and a quantum well pin photodetector. The wavelength converter has a 13 GHz bandwidth and demonstrates error-free operation at 10 Gbit/s with unity gain     

WDM光传输系统2.5Gbit／s光发送模块研究

本文介绍了作者设计，调试的２．５Ｇｂｉｔ／ｓ光发送模块的工作原理、关键技术、典型性能参数，该模块通过控制激光器温度来稳定其中心波长，为波分复用系统的应用提供了具备稳定中心波长特性的光源。     

Demonstration of Wavelength Packet Switched Radio-Over-Fiber System

The authors present a novel concept of employing optical wavelength packet switching in radio-over-fiber access networks. In such a system, the tunable laser (TL) would be employed as a transmitter in the central station. The optical carrier generated by this device would be externally modulated with the data signal upconverted to an RF frequency before being sent to the appropriate base station (BS). If each of the BSs is assigned a unique wavelength, the addressing and routing of traffic could be performed on a packet-by-packet basis with the TL switching between the wavelength assigned to different BSs     

800 Mb/s fibre transmission test using low-loss and low-dispersion single-mode cable

Error-rate performances of a single-mode fibre transmission system are evaluated at wavelengths of 1.18 and 1.31 ?m. It is proven that longitudinal single-mode oscillation of the laser is important in a high-bit-rate system at a finite dispersion wavelength. At a low dispersion wavelength of 1.31 ?m, repeater spacing at 800 Mb/s was extended to 40 km, by developing a low-loss single-mode fibre cable, a stabilised optical transmitter and receiver and a single-mode optical connector.     

A media-access protocol for time- and wavelength-divisionmultiplexed passive star networks

A media access protocol is presented for time- and wavelength-division multiplexed optical passive star networks. The protocol is based on a bus-mesh virtual topology. The network provides minimum latency and high throughput while requiring only a single fixed wavelength transmitter and receiver at each station. The use of nonagile, fixed wavelength devices, readily available with current technology, reduces costs, improves reliability and avoids tuning delays and limitations. The multihop access protocol operates effectively in an environment with lengthy propagation delays. The wavelength-division multiplexing system is required to support only a small, easily achievable number of wavelength channels     

双跳波分复用网络的结构和访问控制协议

本文提出了一种无源星形波分复用网，网络中任意两个用户都能在１￣２跳内通信。本文还提出了波长配置算法，沱能使光器件的调谐范围最小，以降低网络对光器件的要求；它同时还使网络的单跳的比例最大，以降低分组时延。本文还对网络性能进行了理论分析和计算机模拟。