A Simple One-System Solution COF-PON for Metro/Access Networks

In this paper, next-generation ultralong reach code division multiplexing (CDM) on fiber (COF) passive optical network (COF-PON) based on CDM (multiplexing carried out in electrical domain) presented here. We describe the system configuration, COF transceiver, key merits such as bidirectional transmission (on the same wavelength with single fiber), extending the reach by coding gain, and offering huge bandwidth to large number of subscribers by overlaying on coarse wavelength division multiplexing (CWDM)/wavelength division multiplexing (WDM). We believe our newly proposed ultralong reach COF-PON will help to drastically reduce the Capex and Opex costs by consolidating metro and access networks into one simple network. We demonstrated initial experimental results over 100-km bidirectional COF-PON overlay on 4lambda-CWDM channels' transmission without the use of an optical amplifier     

基于熔融拉锥技术的全光纤粗波分复用器

介绍了使用熔融拉锥技术(FBT)制作粗波分复用器(CWDM)中无源器件的过程,并且测试了制作的粗波分复用器无源器件的性能参数。同时我们比较了用熔融拉锥技术制作的粗波分复用器无源器件和用薄膜技术制作的粗波分复用器以及密集波分复用器的无源器件的性能。     

Design of a Cost‐Effective Hybrid‐Type PBEx Providing a High Power Budget in an Asymmetric 10G‐EPON

This paper proposes a cost‐effective hybrid‐type power budget extender (PBEx) that can provide a high power budget of over 45 dB in an asymmetric 10‐Gb/s Ethernet passive optical network (10/1G‐EPON). The hybrid‐type 10/1G‐EPON PBEx comprises a central office terminal (COT) and remote terminal (RT) module supporting four channels and uses a coarse wavelength division multiplexing (CWDM) technology between the COT and RT for a reduction of fiber cost and efficient access network design. The proposed 10/1G‐EPON PBEx can provide over a 40‐km reach and 128‐way split per CWDM wavelength with no modification of a legacy 10/1G‐EPON system and can satisfy the error‐free service in 10¹⁰ packet transmission.     

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.      

Channel Enlargement of PON System Using Nonreciprocal Multiplexing Filter Based on CWDM

We propose a nonreciprocal filter based on coarse wavelength division multiplexing (CWDM) that reduces the upstream channel insertion loss in a passive optical network (PON). We also propose a method to increase the number of channels/optical network units (ONUs) in PON systems using the proposed filter to reduce the service cost per subscriber. Experimental results show that the PON system with the proposed 4‐channel filter can reduce the power budget of the upstream and increase the number of ONUs by 3 to 4 times that of a conventional time‐division multiplexing PON.     

Radio-Frequency Self-Referencing Technique With Enhanced Sensitivity for Coarse WDM Fiber Optic Intensity Sensors

A self-referenced passive optical network (PON) with coarse wavelength division multiplexing (CWDM) is reported for remotely addressing optical intensity sensors with enhanced sensitivity. The self-referencing remote configuration is described as a finite-impulse-response (FIR) filter in reflective operation using two fiber Bragg gratings (FBG) and a fiber delay line. The antisymmetrical phase response of the configuration permits to achieve a self-referencing measurement parameter two times more sensitive than reported previously. To enhance the power budget of the network, CWDM devices with low insertion losses are used for spectral splitting of a radio-frequency (RF) modulated broadband light source (BLS). The network topology and the sensor's interrogation technique are theoretically analyzed and experimental results validating the models are reported.     

Demonstration of RSOA‐Based 20 Gb/s Linear Bus WDM‐PON with Simple Optical Add‐Drop Node Structure

We demonstrate a linear bus wavelength‐reused gigabit wavelength‐division multiplexing passive optical network (WDM‐PON) with multiple optical add‐drop nodes. A commercially available reflective semiconductor optical amplifier‐based WDM‐PON has a sufficient power budget to provide multiple optical add/drop nodes in 16 WDM channels. Sixteen 1.25 Gb/s WDM channels are successfully transmitted over 20 km of single‐mode fiber with four optical add/drop multiplexers, even with 32 dB reflection and chromatic dispersion in the link.     

1.25-Gb/s bidirectional colorless WDM-PON based on RSOA using subcarrier detection and optical carrier suppression

A new architecture for bidirectional gigabit colorless wavelength division multiplexed-passive optical network system based on a reflective semiconductor optical amplifier is proposed. It uses techniques of both optical carrier suppression and subcarrier multiplexing. There is no impact of a downlink signal on an uplink one due to the wavelength reuse because a light from a single optical source is divided into two parts for uplink and downlink transmissions. One is modulated by a downlink signal and the other, which is transformed into two sidebands with a suppressed optical carrier, is utilized for an uplink transmission. An uplink data is recovered by subcarrier multiplexing technique. 1.25-Gb/s error-free transmissions of both uplink and downlink are demonstrated experimentally.     

Next generation hierarchical CWDM/TDM-PON network with scalable bandwidth deliverability to the premises

Long haul optical networks have been on focus for more than two decades. With the advent of dense wavelength division multiplexing technology, optical long haul fiber networks have been so successful in delivering an unprecedented amount of bandwidth that they outperformed the traffic deliverability from/to the access network by orders of magnitude. The reason was a cost-efficiency mismatch; long haul ultra-high bandwidth networks can take advantage of state of the art and costly technology, which cost-sensitive access networks cannot. The result was an unbalanced traffic flow from/to access points to the network if one compares the aggregate flow of the long haul network with that of the access. Nevertheless, over the last decade technology at the access advanced and new standards have been developed so that in the access layer of the overall communications network the focus has shifted onto fiber optic access again. Thus, in the optical regime, two proposals have prevailed. One uses a time division multiplexing (TDM) scheme over a single wavelength and a comprehensive timing protocol, and the other uses coarse wavelength division multiplexing (CWDM) technology. Each technology has advantages and disadvantages, and the one attempts to address the disadvantages of the other. In this paper we describe a hierarchical CWDM/TDM passive optical network (PON). Our access network architecture is scalable, it is flexible to accommodate one of several topologies simultaneously, and it delivers any type of payload, synchronous and asynchronous that spans from DS0 to Gbps. We discuss the bandwidth flexibility, versatility, resiliency and cost efficiency of the access network. We also demonstrate that our network can deliver payload to more than 16,000 end-users using simple and existing optical technology. Thus, if one considers cost per bandwidth or per user, the cost-efficiency outperforms any previous PON access network. Moreover, we provide simulation results to support the viability of our network architecture.     

Optical design and analysis of CWDM upstream TWDM PON for NG-PON2

For passively reach-extended next-generation passive optical networks (NG-PONs), we propose an asymmetric hybrid PON architecture and wavelength plan for using eight 2.5 Gbit/s coarse wavelength division multiplexing (CWDM) in the upstream direction and eight 10 Gbit/s dense wavelength division multiplexing (DWDM) in the downstream direction, called Cu-TWDM PON. The power budget feasibilities, the optical path losses, and the dispersion power penalties in the CWDM upstream wavelengths are precisely investigated in terms of related specifications required to enhance the network coverage to over 40 km with single-mode fibers (SMFs) based on ITU-T G.652.A and B and Corning’s SMF-28e, as the worst-case and the practical-case feasibilities, respectively. We also report on 10 Gbit/s and 2.5 Gbit/s transmission experiments up to 60 km for the downstream and upstream links. Based on the analyses and experimental results, we provide guidelines for the physical media dependent layer specification of Cu-TWDM PON for NG-PON applications.     

Bidirectional optical amplifier for time transfer using bidirectional WDM transmission

In this letter, we propose a bidirectional optical amplification scheme for fiber-optic time transfer based on bidirectional wavelength-division multiplexing (WDM) transmission. The proposed scheme employs single unidirectional erbium-doped fiber amplifier (Uni-EDFA) for commercial optical networks to implement bidirectional optical amplification. Since including isolators, the effect of backscattering due to the accumulated amplification can be efficiently suppressed by the proposed amplifier. The proposed scheme is validated over different length fiber links in laboratory. Experimental results show that the proposed amplifier can support fiber-optic time transfer over several thousands of kilometers with an additional bidirectional delay difference fluctuation at picosecond magnitude.     

光纤参量放大器的最新进展

从单抽运和双抽运光纤参量放大器两种结构展开论述,着重介绍了光纤参量放大器对信号的放大能力及双抽运光纤参量放大器作为波分复用或密集波分复用系统放大器的可能性和所面临的问题,表明具有高增益和宽带宽的光纤参量放大器有可能成为新一代的光放大器.最后介绍了波长转换器方面的最新进展及双抽运偏振态相互正交时的光纤参量放大器在波长转换方面的独特性能.     

波分复用-光时分复用波长转换信号的消光比研究

对基于半导体光放大器(SOA)交叉增益调制(XGM)效应的全光波分复用一光时分复用(WDM—OTDM)转换后的两路时分复用输出信号的消光比(ER)特性进行了分析。研究了两路波分复用的输入抽运光和探测光的功率、波长、抽运光的消光比、数据速率以及半导体光放大器的偏置电流、腔长和模场限制因子对转换信号消光比的影响。模拟结果表明，增大抽运光输入功率，选择长波长抽运光，可以增加转换光相应信道消光比，但减小了相邻信道的输出消光比；增加抽运光消光比，可以提高转换光消光比，但各个信道增长幅度不同；减小探测光输入功率，选取短波长探测光波长，增加半导体光放大器的腔长和模场限制因子以及大的偏置电流可提高转换光消光比；对于两路或多路波分复用信号转换时分复用信号的过程中，一定要考虑转换光每个信道消光比的均衡。     

S-C-L triple-band double-pass erbium-doped silica fiber amplifier with an embedded DCF module for CWDM applications

In this paper, the authors present a double-pass triple-band doped fiber amplifier including an embedded dispersion-compensating fiber. The amplifier employs only silica-based erbium-doped fibers to achieve signal amplification over S-, C-, and L-bands. Experimental characterization is carried out in terms gain and noise figure over the coarse-wavelength-division-multiplexing (CWDM) wavelength grid. By providing optical gain to seven CWDM channels spectrally located between 1490 and 1610 nm, the amplifier can extend the reach of a CWDM optical bus well beyond the 100-km limit.     

Power budget analysis of dual/single feeder fiber WDMPON

This paper investigates how to reduce the cost of wavelength division multiplexing passive optical network （WDM- PON） by comparing the transmission performance of bidirectional single feeder fiber and dual feeder fiber. Comparison is performed on the basis of power budgeting and cost of both arrangements. Simulation results using Optisystem show that the performance of a single feeder fiber is almost equivalent to that of a dual feeder fiber. Therefore, the single feeder fiber WDM-PON can efficiently replace the dual feeder fiber WDM-PON with the minimum deterioration in system performance and reduction in cost.     

粗波分复用及其扩容技术

分析比较了粗波分复用(CWDM)技术与密集波分复用(DWDM)技术的异同,总结了CWDM技术的优点与不足之处,针对CWDM系统扩容性差的缺陷,给出了目前的一些解决方案: 全波段CWDM、CWDM内嵌DWDM波长、提高单位通道传输容量.     

Beyond 5G移动通信室内信号分布系统架构设计

简述并分析了目前2G、3G和4G移动通信室内分布系统的优势和弊端,提出了基于粗波分复用(CWDM)、光学相干调制技术的BCU+ORRU组网架构及光纤MIMO室内分布系统组网架构,给出了其组网架构的优势。     

Multiplexing of fibre optic intensity sensors using fused biconicalwavelength selective couplers

Fused biconical wavelength division multiplexers have been used to replace standard couplers in an intensity-sensor multiplexing network. The wavelength-selective power splitting and the low insertion losses of these devices (<0.2 dB) improve the power budget, while providing network overall optical isolations >30 dB. With this isolation, crosstalk effects in the network are proven to be negligible     

Optimizing amplifier placements in a multiwavelength opticalLAN/MAN: the equally powered-wavelengths case

Wavelength division multiplexing (WDM) provides the ability to utilize the enormous bandwidth offered by optical networks, using today's electronics. WDM-based optical networks employing passive-star couplers have been proposed for deployment in local and metropolitan areas. Optical amplification is often required in such networks to compensate for the signal attenuation along the fiber links and the splitting and coupling losses in the network. However, an optical amplifier has constraints on the maximum gain and the maximum output power it can supply; thus optical amplifier placement becomes a challenging problem. A simplifying assumption for analytical tractability requires that all wavelengths, present at a particular point in a fiber, be at the same power level, viz, the equally powered-wavelengths case. However, previous studies did not minimize the total number of amplifiers while achieving power equalization. In this paper, we formulate the minimization of amplifiers with power equalization as a mixed integer linear program (MILP) that can be solved by a linear program solver. Illustrative examples on sample networks are presented, which demonstrate the characteristics and the advantages of our optimal amplifier placement algorithm     

High-Speed Mode-Locked Quantum-Dot Lasers and Optical Amplifiers

Recent results on GaAs-based high-speed mode-locked quantum-dot (QD) lasers and optical amplifiers with an operation wavelength centered at 1290 nm are reviewed and their complex dependence on device and operating parameters is discussed on the basis of experimental data obtained with integrated fiber-based QD device modules. Hybrid and passive mode locking of QD lasers with repetition frequencies between 5 and 80 GHz, sub-ps pulse widths, ultralow timing jitter down to 190 fs, high output peak power beyond 1 W, and suppression of Q-switching are reported, showing the large potential of this class of devices for O-band optical fiber applications. Results on cw and dynamical characterization of QD semiconductor optical amplifiers (SOAs) are presented. QD amplifiers exhibit a close-to-ideal noise figure of 4 dB and demonstrate multiwavelength amplification of three coarse wavelength division multiplexing (CWDM) wavelengths simultaneously. Modelling of QD polarization dependence shows that it should be possible to achieve polarization insensitive SOAs using vertically coupled QD stacks. Amplification of ultrafast 80 GHz optical combs and bit-error-free data signal amplification at 40 Gb/s with QD SOAs show the potential for their application in future 100 Gb Ethernet networks.