Integrated switches play a crucial role in the development of reconfigurable optical add-drop multiplexers (ROADMs) that have greater flexibility and compactness, ultimately leading to robust ...single-chip solutions. Despite decades of research on switches with various structures and platforms, achieving a balance between dense integration, low insertion loss (IL), and polarization-dependent loss (PDL) remains a significant challenge. In this paper, we propose and demonstrate a 32 × 4 optical switch using high-index doped silica glass (HDSG) for ROADM applications. This switch is designed to route any of the 32 inputs to the express ports or drop any channels from 32 inputs to the target 4 drop ports or add any of the 4 ports to any of the 32 express channels. The switch comprises 188 Mach-Zehnder Interferometer (MZI) type switch elements, 88 optical vias for the 44 optical bridges, and 618 waveguide-waveguide crossings with three-dimensional (3D) structures. At 1550 nm, the fiber-to-fiber loss for each express channel is below 2 dB, and across the C and L bands, below 3 dB. For each input channel to all 4 drop/add channels at 1550 nm, the loss is less than 3.5 dB and less than 5 dB across the C and L bands. The PDLs for all express and input channels to the 4 drop/add channels are below 0.3 dB over the C band, and the crosstalk is under -50 dB for both the C and L bands.
To overcome the Internet ossification, network virtualization has been proposed as a promising method because of its advantages (e.g., on-demand and efficient resource allocation). Virtual network ...embedding (VNE) is one of the main challenges for network virtualization. Energy costs of servers in data centers (DCs) aremajor contributions to the power consumption in information and communication technology. Therefore, VNE should consider both acceptance ratio and power consumption. In this paper, a mixed integer linear programming model is proposed with the objective of minimizing the total power consumption in software- defined optical data center networks by reducing the active data centers and power-consuming network components. In addition, the coordinates of nodes and delay of links are considered for a more realistic scenario. Compared with the existing node ranking method, the proposed global topology resource (GTR) can effectively evaluate the possibility of each DC node to host virtual nodes. Based on the GTR method, we propose a location-aware energy efficient VNE algorithm, namely GTR-VNE. Simulation results show that GTR-VNE can obtain up to 9.3% and 5% improvement of power consumption and acceptance ratio compared with benchmarks. Furthermore, based on GTR and artificial intelligence ant colony optimization (ACO), another energy efficient algorithm, ACO-VNE, is proposed.ACO-VNE can obtain up to 28.7% improvement in power consumption compared with GTR-VNE. In addition, ACO-VNE has better performance in terms of revenue cost ratio and acceptance ratio.
We demonstrate concepts and results of a field trial for a flexible-rate passive optical network (FLCS-PON), which delivers bitrates up to 100 Gbit/s and allows for adaptations in the transmission ...method to match the users' channel conditions and optimize throughput. FLCS-PON builds on top of the hardware ecosystem that will be developed for ITU-T 50 Gbit/s PON and employs three new ingredients: optical network unit (ONU) grouping, flexible modulation format, and flexible forward error correction (FEC) code rate. Together, these techniques take advantage of the optical distribution network (ODN) statistics to realize a system capable of more than twofold throughput increase compared to the upcoming 50 Gbit/s PON, but still able to support a full array of deployed fiber edge cases, which are problematic for legacy PONs. In this paper we explain the concepts behind enabling techniques of FLCS-PON. We then report on a field trial over a deployed fiber infrastructure, using a system consisting of one FLCS-PON OLT and two ONUs. We report both pre- and post-forward-error-correction (post-FEC) performance of our system, demonstrating achievable net bitrate over an operator's fiber infrastructure. We realize a downlink transmission at double the speed of ITU-T 50 Gbit/s PON for ONUs exhibiting lower optical path loss (OPL), while simultaneously continue to support ONUs at high OPLs. We additionally realize a record-high 31.5 dB loss budget for 100 Gbit/s transmission using a direct-detection ONU with an optical preamplifier.
We introduce the real-time multitechnology transport layer monitoring to facilitate the coordinated virtualisation of optical and Ethernet networks supported by optical virtualise-able transceivers ...(V-BVT). A monitoring and network resource configuration scheme is proposed to include the hardware monitoring in both Ethernet and Optical layers. The scheme depicts the data and control interactions among multiple network layers under the software defined network background, as well as the application that analyses the monitored data obtained from the database. We also present a reconfiguration algorithm to adaptively modify the composition of virtual optical networks based on two criteria. The proposed monitoring scheme is experimentally demonstrated with OpenFlow extensions for a holistic (re)configuration across both layers in Ethernet switches and V-BVTs.
We report a dual-polarization radio frequency (RF) channelizer based on microcombs. Two high-Q micro-ring resonators (MRRs) with slightly different free spectral ranges (FSRs) are used: one MRR is ...pumped to yield soliton crystal microcombs ("active"), and the other MRR is used as a "passive" periodic optical filter supporting dual-polarization operation to slice the RF spectrum. With the tailored mismatch between the FSRs of the active and passive MRRs, wideband RF spectra can be channelized into multiple segments featuring digital-compatible bandwidths via the Vernier effect. Due to the use of dual-polarization states, the number of channelized spectral segments, and thus the RF instantaneous bandwidth (with a certain spectral resolution), can be doubled. In our experiments, we used 20 microcomb lines with ∼ 49 GHz FSR to achieve 20 channels for each polarization, with high RF spectra slicing resolutions at 144 MHz (TE) and 163 MHz (TM), respectively; achieving an instantaneous RF operation bandwidth of 3.1 GHz (TE) and 2.2 GHz (TM). Our approach paves the path towards monolithically integrated photonic RF receivers (the key components - active and passive MRRs are all fabricated on the same platform) with reduced complexity, size, and unprecedented performance, which is important for wide RF applications with digital-compatible signal detection.
In order to serve the future high-performance network-based Internet applications, optical network virtualization is proposed to offer each application type a dedicated virtual optical network (VON). ...Virtualizeable bandwidth variable transceiver (V-BVT) is a key enabler in supporting the creation of multiple VONs. In this paper, we present a feasible V-BVT architecture that can be a part of a software-defined optical network. The proposed V-BVT has a novelty to offer independent operation, control, and management abilities to the clients or higher level network controllers. In addition, a specific V-BVT virtualization algorithm is proposed, in order to enable the efficient creation of multiple coexisting, but independent virtual transceivers that share the same V-BVT physical resources. The virtual transceiver can provide specific bit rate, subcarrier, modulation format, and a corresponding baud rate to each VON, based on the requirement of the VON demand, V-BVT resources availability, and optical network status. We further realize the proposed V-VBT architecture on an experimental platform with a software-defined network controller. The V-BVT resource allocation through the proposed virtualization algorithm is also performed using the extended OpenFlow protocol. The proposed and experimentally demonstrated V-BVT achieves independence in virtual transceivers control and management in the control plane, while maintaining the coexisting and isolation features in the physical layer.
Optical transport networks with an expanding variety and volume of network data services challenge network providers' ability to provide high-quality service assurance and network management. ...Software-defined networks (SDNs) decouple the data plane and control plane and enable network programmability in optical networks with a centralized network controller. The optical network then becomes more dynamic in network architecture and reconfigures frequently. Dynamic optical networks require all kinds of visibility into application data types, traffic flows, and end-to-end connections. Thus, we propose an SDN-based monitoring framework that expands network analytics to a converged packet and optical network. With a designated monitoring hub, monitoring information from multiple layers are collected and processed in a centralized server. Several monitoring technologies are provided as network services with the architecture-on-demand optical node architecture. The developed network applications on top of the SDN controller process all the collected monitoring information and enable multilayer network analytics based on the SDN-based monitoring framework. Several use cases demonstrated successfully that the developed multilayer network analytics provides powerful tools for network replanning and optimization. The multilayer network analytics enables quality of service recovery to avoid network disruption, optical power equalization at any combining device, and network debugging and restoration in optical networks.
Future high-performance network-based applications are delivered over the high-capacity dynamic optical network. Each of these applications requires dedicated network service, which can be provided ...by the virtual optical network (VON) created by optical network virtualization. The virtualizable bandwidth variable transceiver (V-BVT) is a key enabling technology for optical network virtualization. In this paper, we propose the virtualization of V-BVT to support the virtualization of optical orthogonal frequency-division-multiplexing-based elastic optical network. We present a novel V-BVT architecture, and introduce both online and offline virtualization algorithms for V-BVT. Accordingly, multiple independent but coexisting virtual transceivers that share the same physical transceiver resources are created, in order to serve separate VONs. To guarantee the isolation of the created virtual transceivers together with their quality of transmission (QoT), the impact of physical layer impairments on different V-BVT solutions is also considered and integrated into the virtualization algorithms. In the offline virtualization, both heuristic and integral linear programming methods are proposed, in order to maximize the VON demand accommodation using the given physical V-BVT resources. In the online virtualization, a heuristic method is proposed to accommodate real-time received VON demands. By applying both algorithms, multiple virtual transceivers can be dynamically created based on the bandwidth and QoT of the VON demands. Finally, we evaluate and compare the performance of the proposed algorithms, and also verify the V-BVT transmission performance through simulation studies.
An SDN based monitoring framework is proposed and demonstrated to aggregate multilayer monitoring information and enable end-to-end network analytics for converged packet and optical networks. New ...network functions are demonstrated with the proposed framework.
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