A reconfigurable optical interconnection network for highly parallel architecture

The MONET project ended in November 1999. Over the five year duration of this project, many significant advances were made in optical networking architectures, components, subsystems, systems, and network demonstrations. In this paper, we report on the major accomplishment of the last year of the MONET project, which was the completion and operation of a transparent, reconfigurable optical network in Washington, DC. This paper describes the network and summarizes experimental results achieved in the first months of operation.

The switching and routing is essential for an advanced and reconfigurable optical network, and great efforts have been done for traditional single-mode system. We propose and demonstrate an on-chip switch compatible with mode-division multiplexing system. By controlling the induced phase difference, the functionalities of dynamically routing data channels can be achieved. The proposed switch is experimentally demonstrated with low insertion loss of ~1 dB and high extinction ratio of ~20 dB over the C-band for OFF-ON switchover. For further demonstration, the non-return-to-zero on-off keying signals at 10 Gb/s carried on the two spatial modes are successfully processed. Open and clear eye diagrams can be observed and the bit error rate measurements indicate a good data routing performance.

In this paper, we discuss TCP (transport control protocol data transfers over a reconfigurable optical network. We find the throughput to be diminished by false detection of congestion by TCP congestion control and avoidance mechanisms.

Statistical multiplexing at the optical layer has been considered a critical requirement in order to build the next generation of ultra-high capacity optical transport networks in a cost-efficient manner. However, even today, the state of the art of commercially available optical core networks is based on mature wavelength switching and routing technologies, which lack a transport and control plane architecture that can support statistical traffic multiplexing with guaranteed Quality of Service (QoS) across a wide range of QoS parameters even if they can support fast reconfiguration at msec time scales. For several years, most research efforts have focused on the concepts of Optical Burst Switching (OBS) and Optical Packet Switching (OPS), which are based on the hybrid use of electronic nodes and optical switches to exploit Time Division Multiplexing (TDM) in order to achieve statistical multiplexing and dynamic resource reservation over optical networks. While burst switching has been experimentally proven as a technically feasible technique, its performance suffers especially under strict requirements for QoS guarantees. In this paper we evaluate the performance gains that can be achieved exploiting statistical multiplexing over a large scale core optical network and we demonstrate the efficiency of the CANON architecture (Clustered Architecture for Nodes in an Optical Network) as a viable alternative to OBS, which can achieve both targets for statistical multiplexing gains and QoS guarantees at the same time.

This paper presents an overview of our work on the design, fabrication, and integration of micro/nano-scale optical devices, circuits, and networks. This is an extension of the macro/mega-scale optical networks down to the level of micro/nano-scale optical circuits and networks. The micro/nano-optical circuits and networks are designed to perform the functions of collecting, storing, transporting, processing, switching, routing, and distributing optical signals on boards or on chips. The integrated optical components include micro/nano-scale light sources, waveguides, detectors, switches, modulators, sensors, directional couplers, multi-mode interference devices, AWGs, ring-resonators, photonic crystal devices, plasmonic devices, and quantum devices, made of polymer, silicon and other semiconductor materials. The paper discusses scientific and engineering issues concerning the integration of micro/nano-scale photonic devices, circuits, and networks of ultra-small-scale dimensions to a very large scale integration density as applicable for datacom, telecom, transportation, aero/space/avionic, and bio/sensor systems.

A reconfigurable interconnection network (RIN) is a custom-designed on-chip switching network yielding routing solutions for a pre-given set of applications. Like field programmable gate array (FPGA) routing networks, the RIN is used to make reconfigurable interconnections among functional blocks. Unlike FPGAs, the network topology of a RIN is irregular as it is designed for a given set of routing requirements and optimized for the area cost subject to given delay constraints. In this paper, we propose an automatic design scheme for RINs, including routing specification formulation, graph modelings, network topology designs, routing algorithms and multiplexer-based network circuit implementation. The choice of the design scheme is based on the existing routing network design practices and research, which give feasible solutions. Our scheme is to optimize the designs with the choice of design parameters. A computer-aided design (CAD) tool is developed based on the design scheme, which takes a set of routing requirements as input and produces the corresponding RIN network topology and network circuit in hardware description language format. We present the area costs of various RINs generated by the CAD tool subject to delay constraints, and illustrate the RIN design scheme with a reconfigurable multistream video system.

Computational intelligence in photonics technology and optical networks: A survey and future perspectives

We have designed and constructed a scalable and reconfigurable optical IP network system for use in residential premises. The network system consists of an optical fiber bus, bus interfaces attached to the bus, and a gateway. In the newly constructed network, 8 optical wavelengths in the course WDM standard were allocated to Gigabit optical transceivers and optical add/drop modules, respectively. The performance examination clarified that throughput of around 90 Mbps was obtained even when 8 personal computers belonging to the different 8 sub networks sent packets simultaneously. The scalability was also confirmed by experiment.

Current optical transport networks provide high bandwidth through the use of advanced WDM technology, but are difficult to adapt to the different statistical patterns and quality of service (QoS) demands of future traffic. There has been much debate whether the use of dynamically reconfigurable optical networks would have a number of advantages in accommodating the needs of future traffic demands. Dynamic networks would eliminate the need for frequent opto-electronic conversion in current networks, and may save resources through higher utilization and fast adaptation. Different architectures have been proposed to address this problem: Wavelength-routed optical networks (WRON), optical burst switching (OBS), and optical packet-switching (with increasing granularity and speed of reconfiguration). In this paper we investigate whether these architectures are suitable (necessary?) to meet the demands of future traffic, using an analysis focusing on both modeling and experimental aspects.

With the advances in semiconductor and circuit integrated technologies, the number of IP cores that can be integrated on one chip is becoming larger and larger. The traditional bus interconnection method of System on Chip (SoC) cannot meet the performance requirements of the Multi Processor System on Chip (MPSoC). Network on Chip (NoC) has improved the interconnect performance of IP cores. However, the conventional metallic interconnection constrains NoC to make greater improvement, while the mature of optical device integrated technology makes the trend of applying optical interconnection technology to chip promising. This paper proposes a cluster-based reconfigurable optical network on chip architecture (CRONoC), which uses a high bandwidth optical circuit switching network to transmit the inter-cluster data and an electrical packet switching network to control the optical network and transmit the intra-cluster data. By activating the resonators in the proposed inter-cluster crossbar structure, the topology is reconfigurable. Employing the proposed routing algorithm, the maximum distance of the network is reduced to 3 for the 64 core CRONoC. Finally, the performance of CRONoC in terms of end to end latency and network throughput under different traffic patterns is evaluated with OPNET. The simulation results show that the CRONoC architecture is suitable for the local and collective communications.

In the 1980s optical communications systems smoothly evolved from single-wavelength transmission systems to multiwavelength high capacity ones due to the advent of the optical amplifiers. 30 years later they similarly migrate to optical networking platforms, thanks to the introduction of Reconfigurable Add/Drop Multiplexers (ROADMs) and/or Optical Cross-Connects (OXCs), in order to serve demands for higher capacity systems with long reach and flexibility (Stavdas A, Core and metro networks, Wiley, pp 382–438, 2010; Ramaswami R, Sivarajan K, Optical networks, Morgan Kauffman Publishers, 1998; Agrawal P, Fiber optic communication systems, Wiley, New York, 1997).However, when fiber was installed and became the main medium of the long-reach telecommunication systems, fiber impairments and component performance limitations for what we define today as high-capacity systems were not evident. When Wavelength Division Multiplexing (WDM) was introduced as an efficient way of resource sharing for the cost-efficient increase of the overall system capacity, physical-layer impairments manifested themselves as cross-channel effects. Meanwhile, as the advances in high-speed electronics and optical components allowed the use of higher channel bit rates, more intra-channel physical impairments appeared even as single-channel effects. Furthermore as wavelength switched optical networks (WSONs) are emerging, ROADMs and OXCs have added their own crosstalk and filtering effects on the transmission links, making decisions on how to efficiently design such optical systems even more complicated. In this chapter we will discuss the various physical degradations that affect emerging optical networks.

Optical performance monitoring might play a crucial role in enabling self-managed and reconfigurable high-performance optical networks. We will explore key motivating networking issues as well as potential monitoring techniques.

There is a large demand to increase the material and energy efficiency as well as the format-flexibility of packaging machines due to current market changes, e.g. the increased demand for individualized products and the resulting drop down of batch sizes. These machines are mostly customized products to fulfil the special requirements of the various packaging machine users. Thus, it is important to know the most profitable level of material and energy efficiency as well as format-flexibility for these machines at the beginning of the development phase. The focus of this paper is the introduction of a new model for the economical assessment of format-flexible packaging machines. It is targeted towards machine manufactures during the early stages of development as well as potential machine users in the investment decision process. Further, the model is applicable to consider further capability characteristics of different packaging machines. The introduced model combines the net present value method and the overall equipment effectiveness system. The application of the economic evaluation model will be shown by a practical use case.

A wavelength-routed optical network consists of a number of cross-connects which are interconnected by optical fibers. Transparent optical networks allow signals to bypass extensive electronic signal processing at intermediate nodes. The quality of an optical signal degrades as it travels though several optical components along its lightpath. It is essential to incorporate imapact of the physical impairments in the routing and wavelength assignment (RWA) problem in transparent optical networks. This work compiles a comprehensive survey, from various research publications, of the proposed algorithms that address this issue. The physical layer impairments classification in optical networks are initially presented followed by physical layer impairments (PLI) RWA algorithms and algorithmic approaches for the PLI-RWA problem. Performance metrics for evaluating the performance of the proposed PLI-RWA algorithms are presented at the end of the work. Further research topics are presented in this study.

The desirable features of future optical high-capacity networks include higher stability, reconfigurability and security. In order to enable robust and self-managed automated operation, the network itself should be able to monitor the physical state of the network, automatically diagnose and repair the network, dynamically allocate resources, and redirect traffic. Optical performance monitoring can agilely provide valuable information such that routing tables themselves can dynamically reflect the state of the physical links to the network controller. The key features of the desired monitor include simplicity in implementation, cost-effectiveness, transparency to data formats and rates, and isolation of the specific impairment from the others. We propose and demonstrate novel optical performance monitoring techniques using cost-effective photonic components and artificial neural network-assisted signal processing to continuously monitor multiple impairments and to accommodate different high-speed advanced modulation formats. These monitoring techniques can facilitate rapid identification and isolation of impairments to enhance the dynamic management of the optical high-capacity networks.