A novel symmetric 10 Gbit/s architecture with a single feeder fiber for WDM-PON based on chirp-managed laser

We propose the single feeder fiber architecture for wavelength division multiplexing passive optical network(WDM-PON)based on directly modulated chirp managed laser(CML).The downlink(DL)signal output from the laser is converted to return-to-zero(RZ)differential phase shift signal using a pulse carver.The downstream signal is reused as a carrier for the upstream using intensity modulation technique.Simulation results show the error-free performance at symmetric data rate of 10 Gbit/s per channel with negligible power penalty and improved receiver sensitivity for the uplink(UL),over 25 km standard single-mode fiber(SSMF).A low-cost and reduced circuitry network design is implemented on a single feeder fiber with the elimination of differential encoder and one external modulator.     

Single fiber colorless symmetric WDM-PON architecture using time interleaved remodulation technique for mitigating Rayleigh backscattering resilience

A time interleaved differential phase shift keying (DPSK) remodulation technique is proposed to mitigate the effect of Rayleigh backscattering (RBS)-induced noise in a single fiber colorless wavelength-division-multiplexing passive optical network (WDM-PON). In order to achieve a cost effective optical network unit (ONU) solution without dedicated laser sources for upstream signals to provide optimum symmetric capacity in a colorless WDM-PON, remodulation becomes the core attraction. Also as the performance of colorless WDM-PON systems suffers from the transmission impairments due to RBS, it is mitigated by using this remodulation scheme. Simulation results show that downstream and upstream signals achieve the error-free performance at 10 Gbit/s with negligible penalty, and enhance the tolerance to RBS-induced noise over a 25 km single-mode fiber.     

A novel AWG-based WDM-PON architecture with full protection capability

The higher bandwidth utilization of wavelength-division-multiplexing passive optical networks (WDM-PONs) can be problematic if the link failure is not repaired in a timely manner since major data losses may occur in the event of link failure. Therefore, developing robust WDM-PON architectures with an effective protection capability is an essential task when designing optical access networks. Although the literature contains many proposals for WDM-PON protection schemes, the majority of these schemes protect either the feeder fibers or the distribution fibers, but not both. By exploiting the cyclic properties of the AWG and establishing appropriate interconnections between matched pairs of ONUs such that one ONU in the pair can use the distribution fiber assigned to its partner for backup purposes, the proposed scheme can protect both the feeder fibers and the distribution fibers through the designated protection streams in feeder fiber 3. Additionally, five operational modes of the proposed scheme are detailed with the proposed wavelength assignment scheme, the operational sequence, and the operation flow chart of decision circuit in the ONU/OLT. The analytical results have shown that the proposed scheme not only provides a full protection capability for WDM-PON networks, but also has a lower unavailability, a lower construction cost, and a reduced wavelength requirement than existing representative protection schemes. Finally, an analysis of the power budget and the recovery time has confirmed the practical feasibility of the proposed scheme.     

A Remotely Reconfigurable Remote Node for Next-Generation Access Networks

A remotely reconfigurable remote node (RN) for next-generation (NG) access networks is proposed and demonstrated. The RN is remotely reconfigured by instantaneous optical powering at the central office through feeder fiber and maintained in a passive state by employing optical latching switches (OLSs). The feasibility of the proposed RN is demonstrated by investigating the operating conditions of optical powering for the reconfiguration and its nonlinear effect both for time-division-multiplexing passive optical network (TDM-PON) as legacy services and wavelength-division-multiplexing passive optical network (WDM-PON) as NG services. The existence of OLSs for reconfigurability and crosstalk effect between TDM-PON and WDM-PON are negligible on transmission performance.     

Rayleigh backscattering minimization in single fiber colorless WDM-PON using intensity remodulation technique

The performance of colorless wavelength-division multiplexed passive optical network(WDM-PON) systems suffers from the transmission impairments mainly due to Rayleigh backscattering(RB).In this paper,we propose and demonstrate a single fiber colorless WDM-PON which enhances the tolerance to RB induced noise.The high extinction ratio in both return-to-zero(RZ)-shaped differential phase shift keying(DPSK) downstream(DS) data signal and intensity-remodulated upstream(US) data signal helps to improve the tolerance to RB induced noise.Simulation results show that downstream and upstream signals can achieve error-free performance at 10 Gbit/s with negligible penalty and improve the tolerance to RB induced noise over 25 km standard single-mode fiber.     

Reliable Wavelength-Division-Multiplexed Passive Optical Network Using Novel Protection Scheme

A novel, reliable wavelength-division-multiplexed passive optical network (WDM-PON) with self-protection capability is proposed. By utilizing the routing characteristics of N x N arrayed waveguide grating, the proposed architecture can provide automatic protection against any fiber cut between central office and optical network unit (ONU). Compared with the conventional schemes, this scheme adopts colorless ONUs, thus leading to a decrease in the costs of operation, administration, and maintenance, as well as the production cost. Without the performance degradation, the proposed WDM-PON scheme can offer a reliable network service. In the experiment, the protection performance was demonstrated in the carrier-distributed 1.25-Gb/s WDM transmission over 20-km single-mode fiber.     

First Commercial Deployment of a Colorless Gigabit WDM/TDM Hybrid PON System Using Remote Protocol Terminator

Colorless gigabit wavelength-division-multiplexing (WDM)/time-division-multiplexing (TDM) hybrid passive optical network (PON) using a remote protocol terminator is proposed and experimentally demonstrated. The system consists of reflective semiconductor optical amplifier-based WDM-PON and a legacy TDM-PON, combined with a simple and efficient remote node structure in order to provide high-speed fiber-to-the-home service to a large area with a high population density. The demonstrated system can support 512 subscribers with a single feeder fiber. The performance and feasibility of the system were evaluated by transmitting gigabit per second data including the effects of Rayleigh backscattering and 20 km attenuation. The system has been used by Korea Telecom to provide commercial services in Gwangju, Korea, since March 2009, after successfully passing through the benchmark test. This is the first commercial deployment of a WDM/TDM hybrid PON. It can accommodate field-deployed TDM-PON link without any modification and extend the maximum total reach of PON link by the use of remote protocol termination. Number of subscribers and the allocated bandwidth to the subscribers can be designed by simply changing the splitting ratio.      

一种应用于波分复用无源光网络系统中的滤波片-PIN-TIA阵列光接收组件

设计并实现了一种将密集波分复用(DWDM)薄膜滤波片与光电探测器PIN以及前置放大器TIA集成封装的光接收组件。通过创新设计单模光纤双芯插针和自聚焦透镜的结构,解决了透过密集波分复用滤波片后的反射光偏离轴线带来的耦合问题。并基于该组件实现了32个密集波分复用通道的解复用与信号检测同时完成的波分复用无源光网络(WDM-PON)系统中上行信道阵列接收模块。测试表明模块满足国际电信联盟(ITU-T)中心波长,最小插入损耗为0.3 dB,最大插入损耗为6 dB,响应速率为100 Mbit/s~1.25 Gbit/s。     

Highly Utilized Fiber Plant with Extended Reach and High Splitting Ratio Based on AWG and EDFA Characteristics

In this paper, we propose a hybrid time‐division multiplexing and dense wavelength‐division multiplexing scheme to implement a cost‐effective and scalable long‐reach optical access network (LR‐OAN). Our main objectives are to increase fiber plant utilization, handle upstream and downstream flow through the same input/output port, extend the reach, and increase the splitting ratio. To this end, we propose the use of an arrayed waveguide grating (AWG) and an erbium‐doped fiber amplifier (EDFA) in one configuration. AWG is employed to achieve the first and second objectives, while EDFA is used to achieve the third and fourth objectives. The performance of the proposed LR‐OAN is verified using the Optisystem and Matlab software packages under bit error rate constraints and two different approaches (multifiber and single‐fiber). Although the single‐fiber approach offers a more cost‐effective solution because service is provided to each zone via a common fiber, it imposes additional losses, which leads to a reduction in the length of the feeder fiber from 20 km to 10 km.     

一种基于相位调制环的多波长产生器的WDM-PON

本文首先简单介绍了WDM-PON的技术背景,在此基础上分析WDM-PON的劣势为造价成本高,通过对现存关键技术的研究和对比,提出了一种基于相位调制环的多波长产生器,将这种技术应用于WDM-PON中,大大降低了成本。     

An (OPS-M)-based WDM-PON with functions of wavelength tri-reuse and all-sided fiber protection

In this paper, an optical power splitter module (OPS-M) and (OPS-M)-based WDM-PON are proposed. The symmetry and passivity of OPS-M makes it easy to integrate and dirt cheap in practice. It shows this OPS-M can be widely applied in an optical network. By utilizing the OPS-M, the wavelength tri-reuse is realized. At the same time, the coherent interference can also be eliminated due to cross-wavelength reuse. By introducing matrix operations and orthogonal vector group, the relations among wavelengths, optical network units and their services are shown clearly. By designing structure of ONU, feeder fiber and distributed fiber failures can be self-protected. Besides, the ONUs remain colorless and the system has passivity. By the simulation, feasibility of the scheme is demonstrated.     

一种基于相位调制环的WDM-PON

本文首先简单介绍了WDM-PON的技术背景,在此基础上分析WDM-PON的劣势为造价成本高,通过对现存关键技术的研究和对比,提出了一种基于相位调制环的多波长产生器,将这种技术应用于WDM-PON中,大大降低了成本。     

WDM-PON采用SOA实现无色光传输

波分复用无源光网络（WDM-PON）实现了点到点的连接,可为每个用户提供专有波长,被普遍认为是未来宽带接入的代表性技术。WDM-PON中采用的调制器,既要实现＂无色＂调制,又要保证系统性能,以降低成本。为此,在强度调制直接检测单模光纤（IMDD SMF）连接系统中,采用半导体光放大器（SOA）作为强度调制器,分析了调制信号与波长的相关性,提出了实现无色自适应调制光正交频分复用（AMOOFDM）传输的优化工作条件。     

基于波分复用的无源光网络技术

无源光网络(PON)技术是解决接入网“最后一公里”瓶颈问题最具吸引力的方法之一,特别是近年来光通信技术的发展使得波分复用的无源光网络技术(WDM-PON)的实现在经济和技术上变的可行。首先介绍了一种TDM-PON和WDM-PON共存的系统,并着重阐述了全波分复用的无源光网络(full WDM-PON)技术,对光纤色散、AWG温度稳定性问题以及非线性效应等在WDM-PON建设中需要解决的一些关键技术进行了讨论。     

SONET ring applications for survivable fiber loop networks

Synchronous optical network (SONET) self-healing rings (SHR) are studied in the loop environment. SONET SHR architectures for loop feeder networks are discussed, focusing on three possible dual central office (CO) architectures for fiber loop networks, using SONET SHRs to reduce network costs and provide network service survivability. These architectures reflect an integrated planning concept for SONET networks that eliminates the boundary between the access network and the inter-office network. It is shown that the use of SONET SHRs makes it easy to evolve to a protected dual CO access architecture. Economic and survivability studies are discussed. The economic studies show that using the ring approach yields significant advantages over the traditional diverse protection approach in terms of cost and survivability, especially for the dual CO architectures     

Using 10 Gb/s remodulation DPSK signal in self-restored colorless WDM-PON system

In this investigation, we propose and experimentally demonstrate the remodulation technique using DPSK format in both downlink and uplink traffics with high extinction ratio (ER) in colorless WDM-PON; together with a simple self-restored architecture against fiber fault. Error free operation was achieved in a 20-km-reach 10-Gb/s WDM-PON without dispersion compensation. Comparison with other wavelength remodulation schemes for WDM-PONs is also performed, showing the proposed scheme can be a potential candidate for next generation wavelength reuse WDM-PONs. In addition, the performance of self-protection has also been discussed and analyzed.     

A WDM-PON with DPSK modulated downstream and OOK modulated upstream signals based on symmetric 10 Gbit/s wavelength reused bidirectional reflective SOA

We investigate a wavelength-division-multiplexing passive optical network (WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying (DPSK) downstream signals and on-off keying (OOK) upstream signals, respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier (RSOA) as an intensity modulator at the optical network unit (ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio (ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate (BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.     

WDM-PON的无色ONU技术

波分复用无源光网络(WDM-PON)实现了点到点的连接,可为每个用户提供专有波长,被普遍认为是未来宽带接入的代表性技术.WDM-PON的关键在于:要求采用低成本、"无色"的光网络单元(ONU),以避免波长选择器件所带来的安装、运营以及维护成本的增加.本文简要分析了3种WDM-PON的无色ONU的实现方法,指出无色ONU是构建WDM-PON的一种较理想的解决方案.     

Fiber to the Home Using a PON Infrastructure

Traffic patterns in access networks have evolved from voice- and text-oriented services to video- and image-based services. This change will require new access networks that support high-speed (> 100 Mb/s), symmetric, and guaranteed bandwidths for future video services with high-definition TV quality. To satisfy the required bandwidth over a 20-km transmission distance, single-mode optical fiber is currently the only practical choice. To minimize the cost of implementing an FTTP solution, a passive optical network (PON) that uses a point-to-multipoint architecture is generally considered to be the best approach. There are several multiple-access techniques to share a single PON architecture, and the authors addressed several of these approaches such as time-division multiple access, wavelength-division multiple access, subcarrier multiple access, and code-division multiple access. Among these multiple techniques, they focus on time-division multiplexing (TDM)-PON and wavelength-division multiplexing (WDM)-PON, which will be the most promising candidates for practical future systems. A TDM-PON shares a single-transmission channel with multiple subscribers in time domain. Then, there exists tight coupling between subscribers. A WDM-PON provides point-to-point optical connectivity using a dedicated pair of wavelengths per user. While a TDM-PON appears to be a satisfactory solution for current bandwidth demands, the combination of future data-rate projections and traffic patterns coupled with recent advances in WDM technology may result in WDM-PON becoming the preferred solution for a future proof fiber-based access network     

Tunable OTDR Based on Direct Modulation of Self-Injection-Locked RSOA for In-Service Monitoring of WDM-PON

We propose a tunable optical time-domain reflectometer (OTDR) for in-service monitoring of wavelength- division- multiplexing passive optical networks (WDM-PONs). The proposed method uses a reflective semiconductor optical amplifier, which is self-injection-locked by a tunable fiber Bragg grating. The proposed tunable OTDR has a tuning range of 30 nm and a resolution of 50 m. The performance of the proposed scheme is experimentally evaluated to demonstrate the in-service monitoring of WDM-PON.