Optical Network Elements Research Articles

PERENCANAAN SISTEM OPTICAL TRANSPORT NETWORK (OTN) PADA SISTEM TRANSMISI DWDM

An OTN consists of a set of optical network elements connected by a fiber-optic link. OTN can provide the use of transport, multiplexing, routing, management, supervision and resilience of optical channels. OTN (Optical Transport Network) itself is a technology that can increase network bandwidth and reliability by building network functions into optical networks. . An OTN consists of a set of optical network elements connected by a fiber-optic link.

A Pair of Coupled Waveguides as a Classical Analogue for a Solid-State Qubit.

We have determined conditions when a pair of coupled waveguides, a common element for integrated room-temperature photonics, can act as a qubit based on a system with a double-well potential. Moreover, we have used slow-varying amplitude approximation (SVA) for the "classical" wave equation to study the propagation of electromagnetic beams in a couple of dielectric waveguides both analytically and numerically. As a part of an extension of the optical-mechanical analogy, we have considered examples of "quantum operations" on the electromagnetic wave state in a pair of waveguides. Furthermore, we have provided examples of "quantum-mechanical" calculations of nonlinear transfer functions for the implementation of the considered element in optical neural networks.

Optical filtering impairment monitoring based on model fusion for optical networks.

Reconfigurable optical add-and-drop multiplexer (ROADM) is a key element in optical networks. As several ROADMs are cascaded over long paths, the penalty induced by ROADM has become non-negligible due to the tight optical filtering. In this case, for efficient and reliable network planning and operation, accurate monitoring of optical filtering penalty is very important. In this paper, we propose a real-time optical filtering monitoring scheme based on model fusion. We combine an analytical model based on the digital communications theory of band-limited channels with linear equalization and a data-driven model implemented using artificial neural network (ANN). The scheme can achieve high accuracy and interpretability. Moreover, since the input features are extracted from configuration parameters and receiver digital signal processing (DSP), no additional devices are needed, which is attractive for practical deployment. Extensive simulations and experiments are conducted to investigate the performance of the scheme, and the results show the superior performance.

A General Variable Bandwidth Microring Filter for Lossless Bandwidth Tuning

We propose a general variable bandwidth filter of arbitrary even order based on the sum-difference microring filter architecture. The filter bandwidth can be varied by tuning only the resonant frequencies of the microrings and thus do not require additional controls other than those used to tune the filter center frequency. In addition, we show that there exists a bandwidth tuning range over which the filter exhibits no extra insertion loss and no degradation in the filter shape. We demonstrated a 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> -order variable bandwidth filter in Silicon-on-Insulator, achieving a bandwidth tuning range from 0.3 nm to 1.35 nm with a maximum in-band ripple of 3 dB. The proposed variable bandwidth filter could serve as a key element in elastic optical networks which can support variable data bandwidth allocation on demand.

A security optical tree establishment protocol based on distributed path computation element in multi-domain optical networks

How to build a secure optical tree through signalling mechanism in multi domain optical network is an important problem. To solve the problem, a security optical tree establishment protocol based on distributed Path Computation Element (PCE) in multi-domain optical networks was proposed. The protocol used a distributed PCE architecture. By expanding the optical network control plane and integrating multiple security mechanisms, the new signaling process of establishing a multicast optical tree was designed. The analysis and experimental results showed that, the protocol performed better performance in a malicious environment compared with the typical layered PCE-based protocol.

Fiber-Longitudinal Anomaly Position Identification Over Multi-Span Transmission Link Out of Receiver-end Signals

We have developed a fiber-longitudinal monitor that visualizes distance-wise optical power throughout the entire multi-span link by using the signal waveform obtained by a coherent receiver placed at the receiver-end. This is an in-situ monitor that estimates power profile along the link-longitudinal axis from its incoming signal by employing digital post-processing of coherent receiver data. We demonstrate through experiments that our method can simultaneously visualize and localize multiple power attenuation anomalies over fiber transmission links. This data processing-based monitoring by digital coherent receiver will be a key element in future autonomous optical networks driven by rich information on physical-layer.

Synergy of Photonic Technologies and Software-Defined Networking in the Hyperconnectivity Era

Photonic technologies and software-defined networking (SDN) are key to supporting hyperconnectivity in a globally networked society. We present programmable optical transmission systems and particularly SDN-enabled transceiver architectures for addressing this challenge. Special attention is devoted to promising technologies able to reduce the cost, power consumption, and footprint of the optical subsystems and network elements. This is particularly relevant for future agile and high-capacity metro networks, identified to be the most challenging segment. Specifically, the adoption of high-dense photonic integration and long-wavelength vertical cavity surface emitting lasers is considered for the design of sliceable bandwidth/bitrate variable transceiver architectures supporting hyperconnectivity. Programmability and technological aspects are discussed, as well as recent results and achievements, focusing on opportunities and limitations provided by the proposed solutions. Starting from the identification of programmable parameters, the modeling of photonic transceivers is provided toward their automatic configurability by an SDN controller. An efficient use of available resources is promoted, while fully exploiting the photonic technology potentialities and exploring advanced functionalities that can be provided.

Connection Provisioning for PCE-Based GMPLS Optical Networks

Generalized Multiprotocol Label Switching (GMPLS) networks is capable of allocating suitable route based on the size of the network and computational constraints. In this paper, we propose a connection provisioning strategy for updating the Traffic Engineering Database of Path Computation Element (PCE) in GMPLS optical networks. Control and management plane are used for resource optimization in PCE-based centralized network. We have also proposed connection provisioning for Label Switched Path (LSP) to optimize the resources and to maximize the connection establishment. For provisioning a connection with LSP requests, we have formulated the Integer Linear Programming and constraints to minimize the blocking of connections and network performance. The results obtained shows that the proposed strategy has better network resource utilization with minimum blocking of connections.

Fully SDN-Enabled All-Optical Architecture for Data Center Virtualization with Time and Space Multiplexing

Virtual data center (VDC) solutions provide an environment that is able to quickly scale up, and where virtual machines and network resources can be quickly added on-demand through self-service procedures. VDC providers must support multiple simultaneous tenants with isolated networks on the same physical substrate. The provider must make efficient use of its available physical resources while providing high-bandwidth and low-latency connections to tenants with a variety of VDC configurations. This paper utilizes state-of-the-art optical network elements to provide high-bandwidth optical interconnections and develop a VDC architecture to slice the network and the compute resources dynamically, to efficiently divide the physical network between tenants. We present a data center virtualization architecture with a softwaredefined networking controlled all-optical data plane combining optical circuit switching and a time-shared optical network. Developed network orchestration dynamically translates and provisions VDCs requests onto the optical physical layer. The experimental results show the provisioned bandwidth can be varied by adjusting the number of time slots allocated in the time-division multiplexing (TDM) network. These results lead to recommendations for provisioning TDM connections with different performance characteristics. Moreover, application-level optical switch reconfiguration time is also evaluated to fully understand the impact on application performance in VDC provision. The experimental demonstration confirmed that the developed VDC approach introduces negligible delay and complexity on the network side.

A proposal for an SDN-based SIEPON architecture

Passive Optical Network (PON) elements such as Optical Line Terminal (OLT) and Optical Network Units (ONUs) are currently managed by inflexible legacy network management systems. Software-Defined Networking (SDN) is a new networking paradigm that improves the operation and management of networks. In this paper, we propose a novel architecture, based on the SDN concept, for Ethernet Passive Optical Networks (EPON) that includes the Service Interoperability standard (SIEPON). In our proposal, the OLT is partially virtualized and some of its functionalities are allocated to the core network management system, while the OLT itself is replaced by an OpenFlow (OF) switch. A new MultiPoint MAC Control (MPMC) sublayer extension based on the OpenFlow protocol is presented. This would allow the SDN controller to manage and enhance the resource utilization, flow monitoring, bandwidth assignment, quality-of-service (QoS) guarantees, and energy management of the optical network access, to name a few possibilities. The OpenFlow switch is extended with synchronous ports to retain the time-critical nature of the EPON network. OpenFlow messages are also extended with new functionalities to implement the concept of EPON Service Paths (ESPs). Our simulation-based results demonstrate the effectiveness of the new architecture, while retaining a similar (or improved) performance in terms of delay and throughput when compared to legacy PONs.

Software defined passive optical networks with energy-efficient control strategy

With the rapid growth of new broadband services and traffic flows, Passive Optical Network (PON) is facing the challenge of bandwidth crunch and energy consumption. There are a huge number of optical network elements, such as Optical Line Terminal (OLT) and Optical Network Units (ONU), which can be controlled flexibly and efficiently to improve the performance of PON. Then, software defined networking (SDN) is considered as the optimal choice for the next generation PON because of its advantages of flexible and centralized control capability. Software defined passive optical network (SPON) architecture is designed with OpenFlow protocol extension in this paper, based on which a novel energy-efficient control strategy is proposed and evaluated on SPON testbed. Also, theoretical analysis work for the energy consumption of this architecture has been conducted. Numeric results show that the proposed energy-efficient control strategy can reduce the energy consumption of optical access networks and efficiently facilitate the integration of access and metro networks resources.

Signal penalties induced by different types of optical filters in 100 Gbps PM-DQPSK based optical networks

Optical filters are crucial elements in optical communication networks. However, they seriously affect the signal quality, especially in the concatenation condition. In this paper, we study and simulate the signal penalties induced by five types of filters, including Butterworth, Gaussian, Bessel, Fiber Bragg Grating (FBG) and Fabry–Perot (F–P) filters, in order to optimize the optical network performance. Signal penalties, including both filter concatenation effect and filter induced in-band and out-band crosstalk, are analyzed by eye opening penalty (EOP) and Q-penalty. Simulation results show that the Butterworth filter performs best among these four types of filters. Total Q-penalty induced by a Butterworth filter-based demultiplexer/multiplexer pair, considering both filter concatenation effect and crosstalk, is lower than 0.5dB, when the filter bandwidth is in the range of 42–46GHz. Simulations done in a 100Gbps PM-DQPSK optical network indicate that the permitted cascaded number is 14 and 10 with respect to the case of filters aligned and misaligned, respectively. Penalties induced by laser frequency shift are investigated and the performance of the 3rd-order Butterworth filter is compared to the 4th-order superGaussian filter. Finally, discussions of optical filter performances, including insertion loss, reconfigurability and programmability, are presented.

Analysis of optical signal impairment induced by different types of optical filters in 40 Gbps DQPSK and 100 Gbps PM-DQPSK systems

Optical filters are crucial elements in optical communication networks. However, they severely affect the signal quality due to their non-ideal transfer functions. In order to minimize filter-induced signal impairment, we study and simulate signal impairment caused by four types of filters: Butterworth, Bessel, Fiber Bragg Grating and Fabry–Perot, and the center frequency tolerances of cascaded optical filters are also discussed. Signal impairment is analyzed by the eye opening penalty (EOP) and Q-penalty parameters. Simulation results obtained in single-channel systems show that the Butterworth filter has the best performance. When the center frequencies of all filters are well aligned, 18 Butterworth filters can be cascaded in a 40Gbps DQPSK single-channel system and 12 in a 100Gbps PM-DQPSK single-channel system, with 1-dB EOP. In the case of center frequencies of all filters misaligned with ±5GHz, the permitted value is reduced to 12 and 9 for the 40Gbps DQPSK and 100Gbps PM-DQPSK single-channel systems, respectively. In the 100Gbps PM-DQPSK-based multi-channel systems, even if 0.7±0.3dB more Q-penalty is introduced in comparison with the case of a single-channel, the Butterworth filter also shows the best performance. In addition, research into the Butterworth filter with different orders indicates that the second-order filter has the best performance in single-channel systems, whereas it has a similar performance as the third-order filter in multi-channel systems.

Is green networking beneficial in terms of device lifetime?

This article analyzes the impact that sleep mode (SM)-based green strategies have on the reliability performance of optical and cellular network elements. First, we consider a device in isolation (i.e., not plugged into a network in operation), showing how operational temperature and temperature variations, both introduced by SM, impact its lifetime. We then evaluate, from an operational cost perspective, the impact of these lifetime variations, showing that some devices are critical, that is, their achievable energy savings might not cover the potential additional reparation costs resulting from being put in SM too frequently. Moreover, we present a model for evaluating the impact of SM on the lifetime of a device plugged into an operational network. The analysis considers two case studies (one based on the optical backbone and one on cellular networks) showing that the lifetime of a device is influenced by both the hardware parameters, which depend on the specific design of the device, and the SM parameters, which instead depend on the energy-efficient algorithm used, the network topology, and the traffic variations over time. Our results show that (i) the changes in the operational temperature and the frequency of their variation are two crucial aspects to consider while designing a SM-based green strategy, and (ii) the impact of a certain SM-based strategy on the lifetime of network devices is not homogeneous (i.e., it can vary through the network).

Optical Interconnection Networks Based on Microring Resonators

Optical microring resonators can be integrated on a chip to perform switching operations directly in the optical domain. Thus they become a building block to create switching elements in on-chip optical interconnection networks, which promise to overcome some of the limitations of current electronic networks. However, the peculiar asymmetric power losses of microring resonators impose new constraints on the design and control of on-chip optical networks. In this work, we study the design of multistage interconnection networks optimized for a particular metric that we name the degradation index, which characterizes the asymmetric behavior of microrings. We also propose a routing control algorithm to maximize the overall throughput, considering the maximum allowed degradation index as a constraint.

Energy Efficiency of Electronic and Optical Network Elements

Decoupling of economic growth and energy consumption becomes a very important goal that can be achieved only by increasing the energy efficiency of new technologies and processes, i.e., the ability to provide a higher performance by consuming less energy. Communication networks play a significant role as a crucial part of the information and communication technologies. An adequate and future-ready communication network infrastructure has become one of the most important strategic goals of any government, region, and municipality because a high-capacity network leads to an accelerated development of both business and society. However, an increase in capacity is mostly associated with an increase in both total power consumption and power density of the related telecommunication equipment. Since the current technology is already approaching the fundamental limits with regard to the power density, there is a need to examine new approaches for achieving high energy efficiency. This paper aims to give an overview on possible potentials of new technologies for implementing energy-efficient network elements. It identifies main energy-related issues in high-performance network elements and tries to draw attention to some promising approaches for implementing low-consuming components and networks.

Multi-channel amplitude equalization based on liquid crystal polarization interference filters

We propose the design of a multi-channel amplitude-equalizing polarization interference filter based on stacked liquid crystal birefringent blocks. Each block, which is optimized to control a predefined wavelength channel, consists of three components. The wavelength blocking/transmitting and the equalizing actions are provided by the liquid crystal component whose optical path difference varies between two particular values when its birefringence is electrically controlled. For a typical three-channel equalizing filter, the three liquid crystal cells provide all eight possible combinations to block/transmit channels and also allow us to independently equalize their corresponding levels. The benefit of such a polarization-based filter is that it operates without free-space demultiplexing optics and with no moving parts. It can be used as a key element in the present reconfigurable optical networks.

Ethernet aggregation and core network models for effcient and reliable IPTV services

With the growing interest on wireline network architectures for residential triple-play and business Ethernet services there is a renewed demand for efficient and reliable packet-based transport capabilities between the content providers and the end users. Voice and data traffic carried over a variety of access technologies is collected via technology-specific access networks (e.g., digital subscriber line [xDSL], passive optical network [xPON], and wireless fidelity [WiFi]). Metro and core networks need to aggregate the various user flows from different access network nodes and provide scalable and cost-effective distribution of various flow types (e.g., Internet access, voice, video on demand, and broadcast TV services) to the relevant service access points. Varying quality of service and resiliency requirements for these services are being reflected in a new breed of converged Ethernet and optical network elements with capabilities to interwork the bearer-planes of these two networking technologies seamlessly. Network elements based on Ethernet/Optical converged technology are able to select the most fitting mechanisms from each networking technology to meet the transport requirements for each individual service demand better while providing significantly enhanced implementation and operational efficiencies. This paper discusses network architecture models and network elements addressing these goals. © 2007 Alcatel-Lucent.

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 15 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 15 August 2006

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 1 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 1 August 2006