Bidirectional WDM passive optical network for simultaneous transmission of data and digital broadcast video service

We have demonstrated an easily upgradable bidirectional passive optical network for the simultaneous transmission of wavelength-division-multiplexing channels and digital broadcast video signals. The proposed network could transmit 15 2.5-Gb/s downstream channels, 15 155-Mb/s upstream channels, and one broadcast signal consisting of more than 70 digital video channels.     

A novel self-surviving architecture for next-generation OFDM passive optical network supporting colorless ONUs

In this paper, we propose a novel self-surviving architecture for next-generation orthogonal frequency division multiplexing (OFDM) passive optical network (PON) supporting colorless optical network units. The proposed scheme can protect distribution and feeder fiber simultaneously. Two different frequency bands are used in this proposed system for paratactic OFDM-PON. The disrupt signals can be restored via the fiber links of the neighboring OFDM-PON without special protecting fibers. We analytically and experimentally study the receiver sensitivity to downstream 10 Gb/s OFDM signals and upstream 2.5 Gb/s NRZ signals. The proposed architecture is designed mainly for next-generation PON systems.     

A novel WDM passive optical network architecture supporting two independent multicast data streams

We propose a novel scheme to perform optical multicast overlay of two independent multicast data streams on a wavelength-division-multiplexed (WDM) passive optical network. By controlling a sinusoidal clock signal and shifting the wavelength at the optical line terminal (OLT), the delivery of the two multicast data, being carried by the generated optical tones, can be independently and flexibly controlled. Simultaneous transmission of 10-Gb/s unicast downstream and upstream data as well as two independent 10-Gb/s multicast data was successfully demonstrated.     

长距离波分时分混合复用无源光网络系统

提出一种基于10G EPON的长距离波分时分混合复用无源光网络(HPON)系统.系统下行采用商用化程度高、成本低的连续模式波长转换模块OEO,上行采用响应速度快、适用于突发信号波长转换的全光波长转换模块AOWC.采用掺铒光纤放大器(EDFA)对光信号进行中继放大处理,可以满足100 km接入距离的要求,顺应了接入网和城域网融合的趋势.在系统的上行引入了基于SOA的全光均衡技术,使得上行光信号的幅度保持一致,使用商用10 Gb/s连续接收机替代高成本的突发接收机,降低了系统成本.系统采用扩展盒技术,可以在现有EPON的基础上方便灵活地进行系统升级,不需要改动EPON的ONU和OLT,最大限度地保留了EPON低成本的优势.     

A centralized-light-source WDM access network utilizing inverse-RZ downstream signal with upstream data remodulation

We propose and demonstrate employing inverse-return-to-zero (IRZ) downstream signal format to facilitate upstream data remodulation in a wavelength division multiplexing (WDM) passive optical network (PON) architecture with centralized light sources. The finite optical power in each downstream IRZ bit can be simply remodulated by the upstream data at the optical network unit. This can make each downstream and upstream pair share a single light source and such light reuse can be easily realized. An experiment on 10-Gb/s downstream IRZ signal generation, 2.5-Gb/s upstream signal remodulation, and two-way transmission is successfully demonstrated. The downstream/upstream signal performance in such a PON has also been analyzed, which is useful for system design.     

A novel 1:N protection scheme for WDM passive optical networks

This paper presents a 1:N protection scheme based on the cyclic property of an array waveguide grating and a specific connection pattern among the optical network units (ONUs). The proposed scheme requires half the number of wavelengths of existing schemes presented in the literature. Although the current scheme requires more fiber links among the ONUs than previous schemes, the network resource demands are greatly reduced and the protection performance is improved.     

WDM passive optical network with subcarrier transmission and baseband detection scheme for laser-free optical network units

We demonstrate a new scheme to achieve source-free optical network units (ONUs) in a wavelength-division-multiplexed passive optical network. The scheme utilizes subcarrier downlink transmission that enables penalty-free remodulation of the downstream signal for upstream transmission. The downstream data can be recovered at baseband either using an optical or electrical technique. In the optical scheme, the downstream signal is passed through a delay interferometer (DI) at the ONUs. A single variety of the DI is applicable to all ONUs that eliminates location-specific devices. Alternatively, the baseband data can be detected using a high-speed photodiode, a dc block, and a rectifier without any optical filter or phase locked loop for down-conversion. The upstream data is also detected at baseband without any modification to conventional receivers. We present experimental and simulation results for the scheme at 2-Gb/s downstream and upstream transmission over 20 km of fiber.     

A novel architecture of hybrid (WDM/TDM) passive optical networks with suitable modulation format

In this paper, we have analyzed the performance and feasibility of a hybrid wavelength division multiplexing/time division multiplexing passive optical network (WDM/TDM) PON system with 128 optical networks units (ONUs). In the proposed network, the triple play services (video, voice and data) are successfully transmitted to a distance of 28 km to all ONUs. In addition, we investigate and compare the proposed hybrid PON for suitability of various modulation formats for different distance. It has been observed that the most suitable data format for hybrid PON network is NRZ Rectangular.     

Bidirectional and simultaneous transmission of baseband and wireless signals over RSOA based WDM radio-over-fiber passive optical network using incoherent light injection technique

Reflective semiconductor optical amplifier (RSOA) based wavelength division multiplexed radio-over-fiber passive optical network (WDM−RoF−PON) has been proposed and demonstrated, to transmit 2.5 Gbps baseband (BB) and 1.25 Gbps wireless data in downstream and 1 Gbps BB data signal in upstream over 25-km single-mode fiber (SMF), and wireless downstream signal over 25-km SMF as well as 5.2 m free space in air. In the downstream, 2.5 Gbps BB data and 1.25 Gbps wireless data are modulated using single-electrode Mach–Zehnder modulator (SD-MZM) based on double-sideband with optical carrier suppression (DSBCS) scheme and simultaneously transmitted by incoherent light injection technique and employing fiber Bragg grating (FBG) at the base station. RSOA is utilized at the user end to reuse the carrier for uplink transmission. High receiver sensitivity, low bit-error-rate (BER) and excellent eye-diagram, eye height are achieved in our proposed network system and the results affirm the acceptability of proposed RSOA based WDM−RoF−PON.     

A novel optical WDM demultiplexer consisting of a simple opticalmultimode guide and an electrical neural network

The operation of the demultiplexer with two different wavelength signals spaced 3 nm apart at 100 Mb/s is discussed. The wavelength resolution of the demultiplexer depends on the differences between the speckle patterns and the recognition performance of the electrical neural network (E-NN). The differences between the patterns become clearer when the guide is longer and the numerical aperture (NA) is larger. The recognition performance is improved by increasing the number of E-NN elements, which have weighting and thresholding functions     

A self-seeded reflective SOA-based optical network unit for optical beat interference robust WDM/SCM-PON link

We have proposed and experimentally demonstrated a novel optical source configuration that uses a self-seeded reflective semiconductor optical amplifier (RSOA) as an optical network unit (ONU) in a wavelength division multiplexed/subcarrier multiplexing (SCM)-passive optical network (PON). A fiber Bragg grating (FBG) was used to obtain a single longitudinal mode of the RSOA. The proposed ONU configuration is simple, cost-effective, and effective regardless of wavelength allocation. Additionally, it would be robust for optical beat interference (OBI) noise. As the ONU is composed only of an RSOA and FBG, the self-seeded RSOA, due to the strong self-injection caused by the reflection of the FBG, has a broad optical spectrum. A self-homodyne apparatus method was performed in order to demonstrate the robustness of the self-seeded RSOA in OBI. To confirm the validity of the proposed scheme, a 16-quadrature amplitude modulation transmission experiment was performed in a 10-, 20-km optical access link with an SCM frequency of 1 GHz. An error vector magnitude of less than 4% for 2 Msps was successfully obtained through the transmission experiment.     

A novel medium access control protocol for passive optical network supporting local area networking capabilities

An alternate solution for Ethernet passive optical networks (EPON) providing local area networking (LAN) capabilities is proposed in this article. Our solution adopts a star coupler-based PON architecture and uses radio frequency subcarrier multiplexed transmission for the LAN traffic delivery. The proposed medium access control (MAC) protocol supports a fully distributed control plane among the optical network units (ONUs) for ONU–ONU communication as well as upstream access to the OLT. The simulation results indicate that the proposed MAC protocol outperforms the others in terms of the average packet end-to-end delay, especially for LAN traffic.     

A 4-wavelength optical multi/demultiplexer for WDM subscriber loop systems using analog baseband video transmission

This paper describes the design principles and performance of optical multi/demultiplexers (MUX/DEMUX's) in wavelength-division multiplexing (WDM) subscriber-loop systems over a 50- μm core diameter, graded-index (GI), multimode fiber, which employ analog baseband video transmission using laser diodes (LD's). In this WDM arrangement, requirements for MUX/DEMUX's are: 1) low insertion loss; 2) no signal degradation caused by optical interchannel crosstalk; 3) only a small amount of analog baseband signal degradation caused by the use of MUX/DEMUX; 4) a small size and simple structure capable of multiplexing three or four wavelengths; and 5) good stability. The newly developed 4-wavelength MUX/DEMUX satisfies the preceding requirements and is suitable for application to WDM subscriber-loop systems using analog baseband signals along with digital signals.     

WDM光网络中一种备用路由下支持优先级的波长分配算法

研究了WDM光网络中的动态业务下的波长分配问题,在无波长转换器的条件下提出了一种改进的动态门限算法.该算法不仅能保证高优先级请求有较低的阻塞率,同时还能优化低优先级请求的阻塞率,从而改善全网的平均阻塞率.此外,该算法利用负载均衡算法,能更加精确地描述波长分配对全网状态的影响,从而更加有效地利用了网络资源.计算机仿真结果证明了该算法的有效性.     

A novel dynamic survivable routing in WDM optical networks with/without sparse wavelength conversion

In this paper, we study the dynamic survivable routing problem, both in optical networks without wavelength conversion and in optical networks with sparse wavelength conversion, and propose a novel hybrid algorithm for it based on the combination of mobile agents technique and genetic algorithms (GA). By keeping a suitable number of mobile agents in the network to cooperatively explore the network states and continuously report cycles (that are formed by two disjoint-link routes) into the routing tables, our new hybrid algorithm can promptly determine the first population of cycles for a new request based on the routing table of its source node, without the time consuming process associated with current GA-based lightpath protection schemes. We further improve the performance of our algorithm by introducing a more advanced fitness function that is suitable for both the above networks. Extensive simulation studies on the ns-2 network simulator show that our hybrid algorithm achieves a significantly lower blocking probability than the conventional survivable routing algorithms for all the cases we studied.     

A reliable WDM optical access network enabling dynamic wavelength allocation and triple-play service

A reliable dual-fiber ring-tree wavelength-division multiplexing optical access network architecture is proposed in this paper. On the one hand, due to the use of differential phase shift keying modulation, triple-play service including point-to-point service and broadcast service is realized. On the other hand, the wavelengths can be allocated dynamically by means of the special design of the remote node. What is more important is this network architecture can provide flexible protection modes for either single or multiple failures as well. The network survivability could be improved largely.     

25 Gbit/s无源光网络技术进展和实验研究

高清视频、虚拟现实等新业务的产生以及PON传输5G移动前传和回传信号的需求,要求PON能支持单波超过10 Gbit/s速率的传输.当线路速率超出10 Gbit/s时,色散和功率预算成为限制系统性能的主要因素.介绍了25 Gbit/s PON系统的研究进展和存在的问题,并对采用基于零色散附近的25 Gbit/s速率的EML、分别基于25 Gbit/s和10 Gbit/s速率的APD接收机进行了实验研究.实验结果表明,采用25 Gbit/s速率的APD,EML的发射光功率设置为+5 dBm,在没有光放大器的情况下,可以达到10 Gbit/s对称的吉比特无源光网络的32 dBm的N2级别的光功率预算.     

A novel hybrid WDM/SCM-PON sharing wavelength for up- and down-link using reflective semiconductor optical amplifier

A hybrid wavelength-division multiplexed/subcarrier multiplexed passive optical network (WDM/SCM-PON) which shares the same wavelength both up-link and down-link is presented by using a reflective semiconductor optical amplifier (RSOA) as a modulator. We investigated down-link of 622 Mb/s using distributed feedback laser diode with direct modulation and 100-Mb/s up-link using an RSOA as a modulator with 900-MHz SCM signal. In our scheme, a novel efficient and cost-effective WDM/SCM-PON using the same wavelength for down/up-link at each optical network unit is proposed and experimentally demonstrated.     

A passive star-configured optical local area network using carrier sense multiple access with a novel collision detector

This work describes design and theoretical performance of a passive star-configured multimode optical fiber local area network that employs carrier sense multiple access with collision detection (CSMA/CD). We introduce a novel collision detection method that uses collision sequences constructed from cyclic error-correcting codes and a sequence weight violation rule. Each transmitter has its own unique sequence and all sequences have identical Hamming weight. The collision detection sequence is inserted in each packet header. Our method enables detection of collisions subject to a wider dynamic range variation than competing methods proposed up to now and is extremely simple. The collision detector consists of a counter which estimates the Hamming weight of the received collision detection sequence. It works both for non-return-to-zero and Manchester coding. The collision detector is analyzed for an avalanche photodiode receiver. The general performance analysis is done both with Gaussian approximations and with method of moments. A dynamic range of 17 dB seems possible for a transmitter with an extinction ratio of 100 and a simple receiver with a fixed threshold. An explicit table of 56 collision detection sequences based on the Golay code is presented.     

Time-multiplexed signals and parallel signal analysis/switch optimization for MEMS-based optical cross-connect

The calibration of the numerous mirror pairs, or switches, in MEMS-mirror optical cross-connect systems is a critical process in their manufacture. Because the number of switch connections for these systems scales quadratically to the number of inputs/outputs, this places great demands on the equipment used to perform testing. We propose and demonstrate a calibration technique for generic optical subsystems based on optical time-division multiplexing (OTDM).