Optical Network Technology Research Articles

Ultra-high-capacity band and space division multiplexing backbone EONs: multi-core versus multi-fiber

Both multi-band and space division multiplexing (SDM) independently represent cost-effective approaches for next-generation optical backbone networks, particularly as data exchange between core data centers reaches the petabit-per-second scale. This paper focuses on different strategies for implementing band and SDM elastic optical network (BSDM EON) technology and analyzes the total network capacity of three sizes of backbone metro-core networks: ultra-long-, long-, and medium-distance networks related to the United States, Japan, and Spain, respectively. Two BSDM strategies are considered, namely, multi-core fibers (MCFs) and BSDM based on standard single-mode fiber (SSMF) bundles of multi-fiber pairs (BuMFPs). For MCF-based BSDM, we evaluated the performance of four manufactured trench-assisted weakly coupled (TAWC) MCFs with 4, 7, 13, and 19 cores. Simulation results reveal that, in the regime of ultra-low (UL) loss and inter-core crosstalk (ICXT), MCF-based throughput can be up to 14% higher than SSMF BuMFP-based BSDM when the core pitch exceeds 43 µm and the loss coefficient is lower than that of standard single-mode fibers. However, increasing the number of cores with (non-)standard cladding diameters, UL loss, and ICXT coefficient is not beneficial. As core counts increase up to 13 for non-standard cladding diameters (<230µm), the core pitch and loss coefficient also increase, leading to degraded performance of MCF-based BSDM compared to SSMF BuMFP-based BSDM. The results indicate that, in scenarios with 19 MFPs, SSFM BuMFP-based BSDM outperforms 19-core MCF-based scenarios, increasing the throughput by 55% to 73%, from medium-backbone networks to ultra-long ones.

Modulation Format Recognition Scheme Based on Discriminant Network in Coherent Optical Communication System

In this paper, we skillfully utilize the discriminative ability of the discriminator to construct a conditional generative adversarial network, and propose a scheme that uses few symbols to achieve high accuracy recognition of modulation formats under low signal-to-noise ratio conditions in coherent optical communication. In the one thousand kilometres G.654E optical fiber transmission system, transmission experiments are conducted on the PDM-QPSK/-8PSK/-16QAM/-32QAM/-64QAM modulation format at 8G/16G/32G baud rates, and the signal-to-noise ratio parameters are traversed under experimental conditions. As a key technology in the next-generation elastic optical networks, the modulation format recognition scheme proposed in this paper achieves 100% recognition of the above five modulation formats without distinguishing signal transmission rates. The optical signal-to-noise ratio thresholds required to achieve 100% recognition accuracy are 12.4 dB, 14.3 dB, 15.4 dB, 16.2 dB, and 17.3 dB, respectively.

Virtualization and energy management optimization of high speed computer network data centers based on optical switching and network technology

With the development of cloud computing and big data technology, the scale and complexity of data centers are increasing, and the thermal energy consumption management of computer processors can effectively improve the energy efficiency of data centers and reduce operating costs. Therefore, this study discusses the application of high-speed computer network architecture based on optical switching and network technology in data center virtualization. By constructing a high-speed computer network model based on optical switching technology, virtualization technology is used to dynamically schedule and manage resources, combined with real-time monitoring system, and the energy consumption data of the processor is collected. Using the data analysis method, the energy consumption performance under different load conditions is evaluated and the optimization strategy is proposed. The experimental results show that the network architecture using optical switching technology significantly reduces the latency of data center and improves the resource utilization. In the thermal management of the processor, dynamic resource scheduling successfully reduces the energy consumption and effectively maintains the stability and performance of the system. As a result, data center virtualization solutions based on optical switching and networking technologies can significantly optimize the power management of computer processors and improve overall energy efficiency.

Crosstalk- and fragmentation-aware survivable routing, modulation, space, and spectrum assignment using Ant Colony Optimization

The use of Space Division Multiplexing (SDM) technology in Elastic Optical Networks (EONs) is a promising solution to improve the transport capability and flexibility required by next-generation applications. In this work, we have illustrated that Ant Colony Optimization (ACO) algorithms can be incorporated into the network control plane and associated with a crankback mechanism to provision and restore lightpaths in a fully distributed manner. In effect, by tackling the challenging Routing, Modulation, Spectrum, and Space Assignment (RMSSA) problem, ACO algorithms can address the inter-core crosstalk and spectrum fragmentation that may limit the potential of the SDM-EON. By comparing different levels of resource state accuracy at the control plane, the simulation results demonstrate the superior performance of the ACO algorithms compared to routing algorithms based on a centralized control plane with a link-state routing protocol, showcasing lower bandwidth blocking rate, comparable restorability, controlled crosstalk levels, and higher scalability, all achieved without a significant increase in setup and restoration times.

University campus network planning and design based on GPON technology

With the continuous development of Internet applications, in order to meet the increasing demands of teachers and students for the campus network in teaching, scientific research, office work and daily life, it is necessary to build a network environment that can meet the needs of smart campuses and future new applications. This paper makes an in-depth analysis of the current situation of campus networks, uses Gigabit Passive Optical Network (GPON) technology to upgrade and transform the existing network, reduces the cost of switching equipment and maintenance difficulty, improves the network transmission rate, increases the upper limit of campus network user access, and effectively solves the problem of separation between wired and wireless networks.

Resilience enhancement in open network–cloud ecosystems through disaggregation and cooperation [Invited

To accommodate the growing demand for cloud services, telecom carriers’ networks and datacenter (DC) facilities form large network–cloud ecosystems (ecosystems for short) physically supporting these services. These large-scale ecosystems are continuously evolving and must be highly resilient to support critical services. Open and disaggregated optical-networking technologies promise to enhance the interoperability across telecom carriers and DC operators, thanks to their open interfaces in both the data plane and control/management plane. In the first part of this paper, we focus on a single entity (e.g., a telecom carrier or an emerging telecom/DC partnership company) that owns both the network and DC infrastructures in the ecosystem. We introduce a solution by leveraging open and disaggregated technologies to enhance the resilience of the optical networks within a multi-vendor and multi-domain ecosystem. In the second part of this paper, we consider the case when the networks and DCs are owned by different entities. Also, in this case, cooperation among datacenter providers (DCPs) and carriers is crucial to provide failure/disaster resilience to today’s cloud services. However, such cooperation is more challenging since DCPs and carriers, being different entities, may not disclose confidential information, e.g., detailed resource availability. Hence, we introduce a solution to enhance the resilience of such multi-entity ecosystems through cooperation between DCPs and carriers without violating confidentiality.

Advances in Adaptive Filtering for Coherent Dual-Polarization Optical Communication Systems and Their Integration in Dynamic Optical Networks

A thorough examination of current developments in adaptive filtering for coherent dualpolarization optical communication systems is provided in this work. The emphasis is on high-capacity networks made possible by dual-polarization, coherent detection, variable bit-rate transceivers. The review explores the effectiveness of different adaptive algorithms in coherent receivers, the importance of dual polarization, and the function of adaptive filters in reducing channel impairments. The research also sheds light on the tradeoffs and difficulties related to flexible bitrate optical transceivers. The paper comprises an extensive assessment of dynamic optical networks, categorized by network granularity and generation, in addition to the study of adaptive filtering. A comprehensive understanding of the developments in dynamic optical networking technologies is provided by the discussion of the evolution and traits of each generation. The poll also covers optical access networks, emphasizing the acceptance and advantages of optical access protocols as IEEE EPON and ITU-T GPON. The study also examines how digital filtering might be used to manage transmission constraints, highlighting the significance of segmenting digital filtering into distinct blocks. An overview of the types and applications of optical filters utilized in optical communication systems is included in the discussion. The study wraps up with a review of the literature that summarizes current research on optical communication systems, such as studies on adaptive algorithms' convergence properties, coherent dual-polarization receivers, and machine learning's use in optical fiber communication. The contributions of this paper include a thorough analysis of adaptive algorithm performance, a comparative study of dynamic optical networks, and a comprehensive overview of recent research in optical communication systems.

Comparative analysis of passive optical networks using multiple parameters: a review

Abstract The desideratum for high-end communication networks and high-speed data transfer has surged exorbitantly in the contemporary era. To meet this demand, various optical access network technologies have been invented and assembled, including gigabit passive optical networks (GPON), Ethernet passive optical networks (EPON), and wavelength multiplexed passive optical networks (WDM-PON). Due to their huge bandwidth capacity, excellent compatibility, dynamic bandwidth allocation, and dispersion tolerance, these technologies constitute potential substitutes for imparting local loop broadband services. This paper presents a thorough review and comparative analysis of the contemporary evolution in optical access network technologies with an accentuate on their functionality, mechanism, manoeuvre, and applications. We are also looking at the upcoming development of these innovations, including the incorporation of 100 G-EPON connectivity to meet the enhanced bandwidth demands precipitated by IP video, mobile broadband, and the Internet of things (IoT).

Coexistence in future optical access networks from an operator’s perspective [Invited

In this paper, we address the challenges related to the simultaneous operation of legacy and future network technologies in passive optical networks (PONs) and point-to-point topologies. We explore the coexistence issues for various user categories, including residential, enterprise, factories, and mobile users. The future access networks will need to accommodate multiple technologies concurrently. Our paper demonstrates how G-PON, XGS-PON, and 50G-PON can coexist on the same optical distribution network using triple coexistence multi-PON modules. However, there are certain limitations that need to be considered, such as achieving a high optical budget and the associated costs, both in terms of monetary investment and CO2 emissions for technology deployment by operators. Additionally, we emphasize the significance of optical line terminals (OLTs) as crucial network components in the future. OLTs play a central role in supporting the traffic evolution with optimal efficiency in terms of throughput, latency, jitter, and adherence to CO2 emission constraints. Finally, we experimentally demonstrate the first assessment, to our knowledge, of a 50G-PON prototype with optical budget reaching 23.9 dB limited by the downstream (DS). Furthermore, we evaluate the potential limitations regarding coexistence by examining the effects of stimulated Raman scattering between the DS of 50G-PON and the upstream of XGS-PON for the first time with real PON systems.

Improved passive optical network RoF system based vertical cavity-surface emitting laser (VCSEL) optical source external modulation

Passive Optical Network (PON) is a promising 5 G optical fiber network technology, that can enhance reliability data rate, and bandwidth saving. This simulation-based study investigates the feasibility of implementing a vertical cavity-surface emitting laser (VCSEL) optical source along with wavelength-division multiplexing (WDM) for designing a PON radio over fiber (RoF) system that can authorize multi-subscribers, users, to simultaneously use the same optical fiber for Front long-haul data transmission. Three scenarios are proposed: First, a VCSEL, and a Mach–Zehnder Modulator with a distinctive frequency are made accessible to every user in the PON system. Whereas, in the second scenario, a continuous wave (CW) laser is used to replace the VCSEL in the same PON. 16 users are multiplexed by a WDM and transmitted over a link length of 200 km. The system performance is, thus measured in terms of Q-factor, and it is revealed that the VCSEL-based system outperforms the system utilized CW laser to a distance of 150 km, with a maximum gain in the Q-factor of about 4.5. Both postulated systems are able to achieve a maximum transmission distance of 180 km with a minimum Q-factor of 6. Moreover, to minimize, the input current of around 1 mA and the system complexity, a third scenario is presented in which one VCSEL with 193.1 THz is shared among multiple users. The Q-factor performance is then simulated for up to 72 users, revealing that the minimum level of acceptable Q-factor has been maintained up to a link length of 180 km.

On three shades of partial protection in elastic optical networks

Gone have been the days when the allocation of spectrum resources for a demand is over-provisioned due to worst-case based designs and the optical transmission technologies are based on the fixed spectral grid, modulation format and/or line-rate schemes. Elastic optical networks technologies featuring adaptive spectrum allocation mechanisms have been becoming the architecture and technology of choice for future core networks to meet explosive traffic growths in a cost and energy-efficient manner. Partial protection strategies based on the observation that in failure events, a service can tolerate a certain amount of degradation and therefore by reducing the protection traffic in the network, better spectrum utilization could be attained. Such concept has been widely studied in the traditional wavelength division multiplexing (WDM) context and yet has been somehow faded due to the fact that fixed transmission technologies provide limited room for spectral improvements. This paper aims to renew the interest in partial protection and re-adapt it to the context of elastic optical networks. The evolutionary perspective we lay out in this paper identifies a new route for achieving greater spectral efficiency in a pragmatic way by simply differentiating the protection services for each demand rather than the uniform treatment for all demands. As such, we present a new research problem entitled, routing, modulation level, spectrum and protection service assignment which is essentially an extension of the well-established one, that is, routing, modulation level, and spectrum assignment as the (partial) protection service for each demand is taken into account and optimized. Three variants of that problem reflecting shades of applying partial protection are covered in details. Specifically, the first one considers the intuitive case as the amount of protection traffic for each demand is provided as the input to the network planning process while the second one is dedicated to the special case of enforcing the same level of partial protection for all demands. More interesting case emerges in the third variant where given the service level agreement for the total protected network traffic, we provide the optimal solution that determines the protection service for each individual demand so as to minimize the spectral occupancy. Extensive numerical simulations have been conducted in the realistic COST239 network topology and it has been revealed that a remarkable spectral saving could be achieved thanks to introducing partial protection services. Moreover, our results have demonstrated that the demand-wise approach far outperforms the one-size-fits-all one and the difference could be up to 25% in our studied cases.

Perspectives on and the road towards 100 Gb/s TDM PON with intensity-modulation and direct-detection

We assess the status of current generation 25G and 50G time division multiplexed passive optical network (TDM PON) technologies based on leveraging the cost efficiencies of the Ethernet intra-datacenter ecosystem. As a first step towards 100G TDM PON, we predict the real-world impact of a flexible modulation enhancement to 50G PON, whereby four-level pulse amplitude modulation (PAM4) symbols can be transmitted at the same symbol rate as 50 Gb/s PAM2, but only where excess margins permit. We find that sufficient margins are likely to exist to allow for a majority of future 50G PON optical network units to operate at 100 Gb/s PAM4. Next, we look at the options for a 100G PON capable of supporting the full loss budget and reach requirements. There is no technical risk if coherent technology is adopted, but intensity-modulation and direct-detection (IM-DD) will provide lower complexity, lower cost, and lower power dissipation. We evaluate this option and conclude that by following IM-DD Ethernet optics to 100 GBd, single wavelength IM-DD will continue to be feasible for 100G PON and will be a strong contender for the next generation of PON after 50 Gb/s.

Optical label-based cost-effective DWDM optical network performance monitoring using low-bandwidth PD with novel SRS mitigation DSP

Large-scale dense wavelength division multiplexing (DWDM) multi-channel performance monitoring is one of the indispensable technologies for the flexible optical networks. The existing Labelbased monitoring scheme requires expensive optical demultiplexing components/equipment to avoid the influence of stimulated Raman scattering (SRS), which is not only costly and bulky, but also could not monitor the wavelength channels simultaneously. In this paper, a low-cost, high-accuracy monitoring scheme based on Optical Label Method is proposed for DWDM networks, where the optical channel power and node identification (ID), as the main monitoring targets that both can indicate or evaluate the channel connection status, could be efficiently monitored. In the scheme, a novel digital signal processing (DSP) method of SRS mitigation is proposed and demonstrated, and an asynchronous code-division multiple access (A-CDMA) based digital label encoding and decoding method is adopted to distinguish the node ID so that channel initial added node can be accurately verified, thereby wavelength connection status can be reliably monitored by combining the channel power and node ID information. The simulation results show that each wavelength channel power and node ID can be accurately monitored only by low bandwidth photoelectric detector (PD) under the condition of 80 wavelengths and 10 spans at C-band.

Perancangan dan Analisis Jaringan FTTB Berbasis Teknologi GPON Pada Bangunan Hotel

This paper presents the design and implementation of a Fiber To The Building (FTTB) network infrastructure based on Gigabit Passive Optical Network (GPON) technology in a hotel cluster building located in West Sumatra, Indonesia. GPON technology was selected for its cost-effectiveness and efficiency in the distribution area, particularly when the terminal bandwidth is set at ≤500 Mbps. The waterfall method was utilized in the network's design. The results were tested and analyzed across three Open System Interconnection (OSI) layers: the physical layer, represented by the link power budget; the datalink layer, represented by the Traffic Container (T-CONT); and the network layer, represented by the QoS network performance. The link power budget showed a minimum received power of -16.41 dBm on the downlink and -18.95 dBm on the uplink, with a power margin value above zero. T-CONT has been implemented with the fixed bandwidth value set to provide a bandwidth guarantee meeting the minimum requirement of 1.1 Mbps. The network performance of the FTTB GPON demonstrated excellent performance, as per Internet Protocol Harmonization Over Network (TIPHON) standards, recording a latency of 1.18 ms, jitter of 0.18 ms, and zero packet loss

Series Editorial: Optical Communications and Networks

In the first issue of the Optical Communications and Networks Series in 2023, we have selected six fascinating articles reporting on recent advances in optical communications and networking. They address free-space optical (FSO) communications including visible light communication (VLC), intelligent fiber-optic communications leveraging machine learning (ML), passive optical network (PON) technology for industrial networks, and dynamic optical path provisioning for alien access links.

Enabling Next-Generation Industrial Networks with Industrial PON

Traditional industrial networks primarily focus on onsite device operation and worker safety. They do not engage in the ongoing digital transformation with remote control machinery and big data processing. The next-generation of industrial networks is expected to offer high-speed connectivity, intelligent management, and flexible architecture to adapt to technology advances and business competitions. Data from the environment, machinery, and offices should be collected and analyzed to support automated procedures related to an industry. In this article, a network architecture based on the passive optical network (PON) technology, the so-called industrial PON, is proposed to enable the next-generation industrial networks. It manages the network resource via a three-layer structure. Recent industrial PON implementations deployed by a Tier 1 operator are investigated in detail to evaluate the solution feasibility and network performance. Results demonstrate that the industrial PON can connect various business assets, provide data exchange to automate industrial processes, and manage the business to improve production efficiency.

Fiber to The Home (FTTH) Network Design Using Gigabit Passive Optical Network (GPON) Technology Using Link Power Budget and Rise Time Budget Analysis in Cibeber Village Tasikmalaya

Fiber optic is a transmission medium that can transmit information with large capacity. One of the developments in local fiber access networks is FTTH (Fiber to The Home). The construction of the FTTH network uses Gigabit Passive Optical Network (GPON) technology so that it can provide broadband services to customers with a wider range. This research was studied by designing FTTH based on GPON technology in Cibeber Village, Manonjaya District. The existing condition of the FTTH network in Cibeber Village is that there are 2 Optical Distribution Points (ODP) for 20 customers with each ODP having 10 subscribers. From the results of the location survey by measuring the distance to each customer, the furthest distance to the customer for the two ODPs was obtained, so that 2 new ODPs were needed for the design. From the design of the new optical network infrastructure, it has been analyzed using the link power budget and rise time budget method based on the customer with the farthest distance before the addition of ODP has a Power Receive sensitivity of -16.631 dBm to -15.631 dBm on the uplink and -16.644 dBm to -15.574 dBm on the downlink, these results are in accordance with the expected standard, which ranges from -8 dBm to -27 dBm. In calculating the value of the rise time budget for customers after the addition of ODP, it has a value of 0.2044 ns to 0.2039 ns on the uplink and 0.2188 ns to 0.21574 ns on the downlink. This value is still below the standard time limit set by PT. Telkom Indonesia 0.56 ns for uplink and 0.292 ns for downlink. So based on this the results of the design are feasible to implement.

Free Space Optical Communication Networking Technology Based on a Laser Relay Station

Optical communication modulation technology and networking technology are two important technologies for constructing free-space optical (FSO) communication. In this paper, pulse width modulation (PWM) is used to realize free-space optical communication. The process of signal modulation and demodulation is implemented by means of a field programmable gate array (FPGA). An optical communication relay system is constructed to realize communication networking. The binary data bits in the communication process are converted into pulse signals of different widths, the data demodulation process is realized by sampling with a high-speed analog-to-digital converter (ADC), the data level is determined by counting the proportion of high and low voltages sampled in a pulse period. The relay system analyzes the routing target after receiving the pulse signal from the transmitter, and then sends the data to the target receiver. The experimental results show that the constructed system can achieve point-to-multipoint free-space optical communication. Additionally, using ADC to demodulate the received signal increases the stability of the free-space optical communication system. This system provides the design prototype system of FSO communication networking technology.

Bistable All‐Optical Devices Based on Nonlinear Epsilon‐Near‐Zero (ENZ) Materials

AbstractNonlinear and bistable optical systems are a key enabling technology for the next generation optical networks and photonic neural systems with many potential applications in optical logic and information processing. Here, a novel bistable resonator‐free all‐optical waveguide device based on indium tin oxide as nonlinear epsilon‐near‐zero material providing a cost‐efficient and high‐performance binarity photonic platform is proposed. The salient features of the proposed device are compatibility with silicon photonics, enabling sub‐picosecond operation speeds with moderate switching power. The device can act as an optical analogue of memristor or thyristor and can become an enabling element of photonic neural networks not requiring OEO conversions.

Optical Distribution Network Design Using PSO

Fiber To The Home (FTTH) network based on the Gigabit Passive Optical Network (GPON) technology is considered a technology option capable of spreading high-speed Internet. However, the high project cost may make its deployment unfeasible. Given this challenge, we use Particle Swarm Optimization (PSO) to propose an Optical Distribution Network (ODN) design in FTTH network. The ODN is a region that links the Central Office (CO) and the User Network (UN), that is, a strategic region that needs additional attention. In the literature so far is rare to find a technical-economic analysis of the ODN problem. Therefore, the novelty of this letter is to adapt the PSO, an efficient and fast strategy to be applied to multivariable functions, within an ODN design with technical and economic criteria. Using system-level simulations, we attest that the proposed algorithm achieves 12% cost reduction from the conventional way.