Electro-optic Network Research Articles

Secure remote synchronization and secure key distribution in electro-optic networks revealed by symmetries

Despite the intuition that synchronization of different nodes in coupled oscillator networks results from information exchange between them, it has recently been shown that remote nodes could be partially synchronous even when they are separated by intermediately unsynchronized nodes. Here based on electro-optic system, we report on a more stronger form of such synchronization pattern that is termed as secure remote synchronization, in which two remotely separated nodes could have identically synchronized dynamical behaviors while the rest of the network are both statistically and information-theoretically incoherent relative to the two synchronized nodes. The generalized form of mirror symmetry in the network structure is identified to be a key mechanism allowing for secure remote synchronization. Moreover, this synchronization mode is robust against a wild range of system parameters and noise perturbing the intermediary dynamics. The lack of information about the synchronized dynamics in the rest of the network suggests that our results could potentially lead to network-based solutions for secure key distribution and secure communication.

Extracting S-parameters of bilateral electro-optic network for lightwave component analyzer calibration

A new method for extracting E/O and O/E S-parameters of a bilateral electro-optic network (BEON) is theoretically proposed. It is based on measuring reflection coefficients from three optical loads: an absorber and two mirrors. This technique includes two series of reflections measurements: first when loads are connected to optical port of BEON directly and second when loads are connected in series with optical waveguide of fixed length. Using two BEONs and this calibration technique allows to make calibrated lightwave measurements with a standard microwave network analyzer without using additional electro-optical equipment such as lightwave component analyzer or optical heterodyne techniques.

Cluster synchronization and isolated desynchronization in complex networks with symmetries.

Synchronization is of central importance in power distribution, telecommunication, neuronal and biological networks. Many networks are observed to produce patterns of synchronized clusters, but it has been difficult to predict these clusters or understand the conditions under which they form. Here we present a new framework and develop techniques for the analysis of network dynamics that shows the connection between network symmetries and cluster formation. The connection between symmetries and cluster synchronization is experimentally confirmed in the context of real networks with heterogeneities and noise using an electro-optic network. We experimentally observe and theoretically predict a surprising phenomenon in which some clusters lose synchrony without disturbing the others. Our analysis shows that such behaviour will occur in a wide variety of networks and node dynamics. The results could guide the design of new power grid systems or lead to new understanding of the dynamical behaviour of networks ranging from neural to social.

Half a century of optics in computing—a personal perspective [Invited

Optical signal processing and computing was triggered by the invention of the laser. Starting practically in 1960, it really took off with the introduction of the spatial-matched filter in 1964. Almost half a century later, research and engineering activity in the field continues unabated but in directions that could not have been anticipated in those early days. This paper presents an overview of the developments in the field, discussing the advantages, disadvantages, and limitations of optics in computing paradigms to indicate where and how optics can be exploited in this area. Initially, optical methods were introduced for processing analog signals. Early attempts to extend optical methods toward digital processing failed because the differences between photons and electrons were not properly appreciated. In the last part of the paper we show that some novel concepts and advanced technology may revitalize also optical processes within the digital computing world. This latter development is demonstrated by digital logic functions implemented on simple electro-optic networks. (My personal perspective on the role of optics in computing is deeply rooted in many years of collaboration with my late friend, H. John Caulfield, and I dedicate this paper to his memory.).

基于Crossbar电光开关网络的偏振结构自由空间全光路由器

基于Crossbar电光开关网络的偏振结构自由空间全光路由器

Optical IP Switching: A Flow-Based Approach to Distributed Cross-Layer Provisioning

Technological improvements, such as erbium-doped fiber amplifiers (EDFAs) and wavelength division multiplexing (WDM), have revolutionized optical transmission, boosting the development and worldwide deployment of the Internet. Similar progress has not yet impacted the routing layer, as current IP routing technology struggles to deliver the necessary bandwidth at competitive costs. Hybrid electro-optical architectures, where dynamical optical circuit switching is combined with legacy packet routing, have been introduced in the past few years as promising solutions to reduce costs at the IP layer and to deliver new revenue-generating services and applications. Most of the architectures currently proposed have focused on end-to-end lightpath provisioning, coordinated through a centralized management plane. In this paper we propose optical IP switching (OIS), a hybrid electro-optical network architecture that combines IP routing and wavelength switching, using a distributed decision-making process. We report technical and economic analysis, based on simulations obtained through real traffic traces and routing tables, that compare our distributed model to an opaque IP-over-WDM and centralized, transparent overlay models. We also report testbed results that analyze the effect of dynamic transparent switching operation on the TCP and UDP transport protocols. The results obtained show that distributed provisioning based on local traffic analysis can be feasible, although more work is required to evaluate the efficacy of optimization techniques on distributed network models.

Implementation and calibration of a two-port electrooptic network analyzer

A novel bidirectional electrooptic network analyzer has been demonstrated which enables the full S-parameter characterization of both electrooptic (E/O) and optoelectronic (O/E) components using a single connection of the device-under-test to the test ports. A combined two-tier E/O and O/E calibration is proposed. Measurement results which validate both the analyzer architecture and the calibration are presented.

Polymer network structure and electro-optic performance of polymer stabilized cholesteric textures II. The effect of UV curing conditions

The effect of UV curing intensity and curing time on the electro-optic behaviour and network morphology of reverse mode polymer stabilized cholesteric textures (PSCTs) has been studied. Scanning electron micrographs indicate that increasing the curing intensity generally results in a more open polymer network characterized by a larger average void size, while the morphology of the individual strands remains largely unchanged. In addition, as the polymerization process proceeds, voids within the network are observed to decrease in size. PSCTs with sufficiently large network voids exhibit a two-stage switching behaviour consistent with a model in which the cholesteric liquid crystal is divided between two distinct environments one in which the liquid crystal is strongly dominated by the polymer network, the other in which a bulk-like behaviour, comparable to the unstabilized cholesteric material, is observed.

Polymer network structure and electro-optic performance of polymer stabilized cholesteric textures I. The influence of curing temperature

The effect of curing temperature on the electro-optic behaviour and network morphology of reverse mode polymer stabilized cholesteric textures (PSCTs) has been studied. Scanning electron micrographs indicate that increasing the curing temperature generally results in a larger average void size within a polymer network, while the morphology of the individual strands (which varies significantly for different monomers) remains largely unchanged. PSCTs with sufficiently large network voids exhibit a two-stage switching behaviour consistent with a model in which the cholesteric liquid crystal is divided between two distinct environments one in which the liquid crystal is strongly dominated by the polymer network, the other in which a bulk-like behaviour, comparable to the unstabilized cholesteric material, is observed.

Security issues in all-optical networks

All-optical networks are emerging as a promising technology for terabit per second class communications. However, they are intrinsically different from electro-optical networks, particularly because they do not regenerate signals in the network. The characteristics of all-optical network components and architectures manifest new and still unstudied security vulnerabilities but also offer a new array of possible countermeasures. We focus on two types of attacks on the physical security of the network: service disruption, which prevents communication or degrades quality of service (QoS), and tapping, which compromises privacy by providing unauthorized users access to data which may be used for eavesdropping or traffic analysis.

Simulation and implementation of lightwave component characterization using a bilateral electro-optic network

The simulation and implementation of a bilateral electro-optic network has been demonstrated. The advantage of the proposed network is that it can be used as a black box to convert a microwave network analyzer into a two-port lightwave network analyzer. Simulations have been carried out to determine the sensitivity of the bilateral network to optical reflections. Measurement results on one-port optical structures are more accurate than those obtained with commercial lightwave analyzers and indicate the viability of this approach for full two-port lightwave measurements.

Optoelectronic techniques for ultrafast device network analysis to 700 GHz

Recent advances in state-of-the-art optoelectronic techniques are presented for small-signal electronic device network analysis. The impetus for optoelectronic approaches is given by the severely inadequate bandwidth coverage of existing measurement techniques. Based on a comparison of the trade-offs offered by various optoelectronic techniques, external electrooptic sampling was chosen. Then, the three basic building blocks of an electrooptic characterization system are discussed, which cover the areas of wide-band signal measurement, generation and transmission. The building blocks are subsequently integrated into a complete electrooptic network analyser system capable of active device characterization over a 100 GHz bandwidth. These capabilities are demonstrated on a heterojunction field-effect transistor with a directly-measured maximum frequency of oscillation of 94 GHz. Then, the performance of the electrooptic network analyser is optimized by minimizing transmission line losses, and by improving signal generation and measurement geometries. The resulting system exhibits an unprecedented single-measurement bandwidth of 700 GHz on passive structures. The system performance is verified by comparing measured results with simple models of the measured passive structures.

Designing Optical Networks from Simple Switching Elements

An analysis of switching networks and current optical technology reveals that the topology of networks determines the extent to which optics can offer system-level performance advantages over electronic and electrical implementations. For direct connection networks such as mesh networks, hybrid electrooptical networks that employ circuit switching can reduce latency and thereby system throughput by an order of magnitude. For packet switched local area networks, optically controlled electrooptic waveguide crossbar networks provide higher efficiency and also lower latency advantages. To illustrate our thesis, we present two examples of electrooptical waveguide-based network designs. In the first, we describe a new self-routing optical crossbar design, VIPER +, that can be realized by locally controlled 2 × 2 electrooptic switches. The VIPER + crossbar is unique in that it can solve the network access and conflict arbitration problems optoelectronically. Further, by cascading the proposed crossbar networks, larger nonblocking self-routing optical networks can be implemented in modular fashion. The second design based on VIPER + is a waveguide mesh interconnection network that incorporates an optical express router, in which optical channels are accessed for remote processor communications, in an electrical mesh.

General sensitivity enhancement and common-mode compensation principle for interferometric fiber-optic sensors

Numerical simulations are presented which show that, when an optical circuit for common-mode compensation and an electrooptic feedback network for measure and sensitivity enhancement are incorporated into any of four main types of interferometric fiber-optic sensors, measured sensitivity can be enhanced by at least an order of magnitude, while sensitivity to common-mode environmental perturbations (such as source wavelength drift or spatially uniform temperature variation) is drastically reduced. >