Optical Switch

This paper presents a theoretical study on the generation of optical frequency combs (OFCs) using direct modulation of semiconductor laser. Influence of gain suppression on characteristics of the generated OFCs is investigated. The study includes intensive and comprehensive investigations of the temporal and spectral characteristics of the generated OFCs as a function of the gain suppression over a wide range of the bias current. We report on generation of short optical pulses and large numbers of comb lines with low-power flatness under weak gain suppression and/or strong modulation depth when the laser is biased near the threshold. The influence of gain suppression becomes more robust when the laser is biased far above threshold. By adopting the operating parameters, we predict pulses with 60 ps width and 10 comb lines with 2.1 dB flatness when the gain suppression is ignored. Under strong gain suppression, broader pulses (132 ps width) and only five lines with higher flatness of 4.99 dB could be obtained.

One kind of Bragg-spaced all-optical switching has been proposed in this paper, and the quantum dots ensembles are used in it as active layers. By one-dimensional photonic crystal theory and transmission matrix method, we have studied the reflectivity stop band and switching effect based on the ac Stark effect. The reflectivity stop band of this switch can be suppressed or recovered, and the circular dichroism and birefringence are induced by a circle-polarized control light, which result in a significant polarization switching effect. This switching structure shows great advantages of lower requirement of pump light intensity, larger contrast ratio than that of Bragg-spaced quantum wells with the same period, especially this switching can be used at room temperature theoretically. So we predict that there are prodigious prospects for its using in high speed optical communications as all-optical switching.

Optical bistable devices are fundamental to digital photonics as building blocks of switches, logic gates, and memories in future computer systems. Here, we demonstrate both optical and electrical bistability and capability for switching in a single transistor operated at room temperature. The electro-optical hysteresis is explained by the interaction of electron-hole (e-h) generation and recombination dynamics with the cavity photon modulation in different switching paths. The switch-UP and switch-DOWN threshold voltages are determined by the rate difference of photon generation at the base quantum-well and the photon absorption via intra-cavity photon-assisted tunneling controlled by the collector voltage. Thus, the transistor laser electro-optical bistable switching is programmable with base current and collector voltage, and the basis for high speed optical logic processors.

Due to the growing popularity of optical superchannels and software defined networking, reconfigurable optical add-drop multiplexer (ROADM) architectures for superchannel switching have recently attracted significant attention. ROADMs based on micro electro-mechanical system (MEMS) and liquid crystal-on-silicon (LCoS) technologies are predominantly used. Motivated by requirements for low power, high-speed, small area footprint and compact switching solutions, we propose and demonstrate spatial and wavelength flexible superchannel switching using monolithically integrated silicon photonics (SiP) micro-ring resonators (MRR). We demonstrate the MRRs capabilities and potential to be used as a fundamental building block in ROADMs. Unicast and multicast switching operation of an entire superchannel is demonstrated after transmission over 50 km of standard single mode fiber. The performance of each sub-channel from the 120 Gb/s QPSK Nyquist superchannel is analyzed and degradation in error vector magnitude performance was observed for outer sub-channels due to the 3-dB bandwidth of the MRRs, which is comparable with the superchannel bandwidth. However, all subchannels for all switching cases (unicast, multicast and bi-directional operation) exhibit performance far below the 7% FEC limit. The switching time of the SiP MRR chip is such that high capacity superchannel interconnects between users can be setup and reconfigured on the microsecond timescale.

A thermally driven wavelength-selective switch, based on integrated-optic micro-ring resonators is described. This configuration allows high ON/OFF ratios combined with small dimensions. Measurements of the thermal behaviour of a single resonator confirm the switching capability

The wavelength tuning of a compact microring resonator with a chromium heater is described. A tuning of 12 pm/ • C is measured with extremely low driving power. This property together with the small footprint makes applications feasible in filter or switching arrays.

We present a four channel optical add-drop multiplexer based on vertically coupled microring resonators fabricated in Si3N4/SiO2. The device with a Manhattan-like geometry has a footprint of 0.25 mm2 and can find application in metro-networks. The individual micro-resonators have a 50 μm radius and are thermally tunable over a 4 nm range. The maximum power consumption per ring is 0.5 W. Measurements show that each microring has a bandwidth >10 Gbit and can be thermally tuned in less than 1 ms. The measured on-off resonance in the drop ports of each micro-resonator is 10 dB.

A compact [200 200 m 2 ] wavelength-selective switch based on thermally tunable SiO 2 -Si 3 N 4 microring resonators has been designed and realized. The switch supports gigabit filtering applications in access networks. Spectral measurements show an ON-OFF ratio of 12 dB and a channel separation of 20 dB. The 10-Gb/s measurements on a single ring show no degradation of the modulated signal and a theoretical bit-error rate 10 12 .

A novel wavelength-selective switch based on hermally tunable Si 3NI microring resonators has been design& rsahzed and charactefized. The switch has an ONDFF ratio of 7.5 dB and is made out of two rings which allow neady lull dropping (83%) and can thermally be tuned over 3 nm.

Abstrcrct--We report the characteristics of a four-channel monolithic GaAs optical/electronic selector for applications in fast packet-switched wavelength division multiaccess networks. The selector chip consists of four metal-semiconductor-metal photodetectors sharing a single differential transimpedance amplifier selected by four enhancement-mode MESFET switches. The channel switching time is about 2 ns and no appreciable crosstalk is observed hrn neighboring channels.

A high-speed optical packet switching node using the WDM all optical switch structure is studied in this paper. Teletra c performance of an optical IP packet router is simulated under the self-similar bursty tra c condition. Four di erent control algorithms are investigated for the performance and complexity. A simple round-robin algorithm cannot attain an acceptable performance. Finding minimum bu er occupancy and sorting the packets by length are methods used to improve the IP router performance.

In Data Centers each rack uses a Top-of-Rack (ToR) as a first level switch to connect servers to the aggregation switches. The current paper focuses on a hybrid electrical/optical ToR design, which first, adapts the servers Ethernet traffic to the optical TDMA operation of the core network for supporting optical switching in the Data Center's upper layer and second, it employs optical switching of traffic at the rack level. The proposed ToR architecture is based on an Ethernet switch and FPGA port extensions realizing the required functions to support 20 10Gbps connections, exploit the network routing resources and handle effectively virtual queues.

The in-advance reservation of bandwidth capacity philosophy of Optical Burst Switching architectures via Burst-Control Packets brings high flexibility in the separation of network resources for services with different qualityof-service requirements. In this light, real-time applications can periodically be guaranteed a certain amount of bandwidth reservation for the transmission of traffic with Constant Bit Rate requirements (for instance IP television, VoIP, etc), whilst the remaining capacity may be used for transmission of best-effort traffic of the so-called elastic applications (e-mailing, web browsing, etc). The Polymorphous, Agile and Transparent Optical Networks (PATON) architecture (Qiao et al. IEEE Commu Mag 44(12):104-114 2006) proposes periodic reservation of time-slots over one or several wavelengths of an optical fibre, yet remaining gaps in between them for transmission of best-effort traffic. This work presents a novel analysis of the performance perceived by best-effort traffic which are given full access to optical switching only during a portion of the total time. The following analyses the nonblocking probability among best-effort data bursts that share such available gaps in between the periods of CBR traffic. An exact expression of the non-blocking probability is derived when a single wavelength is used for CBR traffic, along with a lower bound for the case when CBR traffic is transmitted using multiple wavelengths. These results can be of further interest in the optimal design of OBS architectures where the transmission of high-priority real-time traffic and best-effort data coexist over the same wavelength.

Introduction There has recently been much interest in the development of high performance semiconductor optical amplifier (SOA) based switches for computing and other optical networking applications as they offer high on-off switching ratios and provide inherent optical gain. Demonstrations have been made both for switches based on discrete components1 and also partially populated integrated solutions2. To date however monolithic crosspoint devices have been formed with port counts of 4x4, and recently 1x8 port splitters made by active passive integration in quantum well ...

This paper is about the suppression of the relative intensity noise (RIN) peak and phase noise of a diode pumped Neodymium-doped Lithium Niobate (Nd:LiNbO 3) microchip laser. Relaxation oscillations result in about 15-20 dB noise peak above the flat noise at 350 kHz offset frequency. In case of high quality requirements this noise peak is significantly disturbing. In this paper a new approach is presented for the suppression of the RIN peak and phase noise in microchip lasers.

In the present paper, a detailed investigation on the switching behaviour of a nonlinear Mach-Zehnder interferometer (NMZI) has been carried out using beam propagation method (BPM). A thorough investigation on input vs. output characteristic has been carried out by varying different parameters like length of the arms, refractive index of the linear/nonlinear arm, wavelength of the input beams and nonlinear coefficient of the material of the nonlinear arm. The input vs. output characteristic has also been investigated by shifting the balance point of the NMZI. The present paper provides a physically intuitive understanding of the effect of change in different parameters of the NMZI on its switching behaviour.

Energy-efficient programmable photonic integrated circuits (PICs) are the cornerstone of on-chip classical and quantum optical technologies.1,2 Optical phase shifters constitute the fundamental building blocks which enable these programmable PICs. Thus far, carrier modulation and thermooptical effect are the chosen phenomena for ultrafast and low-loss phase shifters, respectively; however, the state and information they carry are lost once the power is turned off—they are volatile. The volatility not only compromises energy efficiency due to their demand for constant power supply, but also precludes them from emerging applications such as in-memory computing. To circumvent this limitation, we introduce a novel phase shifting mechanism that exploits the nonvolatile refractive index modulation upon structural phase transition of Sb2Se3, an ultralow-loss phase change material. A zero-static power and electrically-driven phase shifter was realized on a foundry-processed siliconon-insula...

Reconfigurable photonic systems featuring minimal power consumption are crucial for integrated optical devices in real‐world technology. Current active devices available in foundries, however, use volatile methods to modulate light, requiring a constant supply of power and significant form factors. Essential aspects to overcome these issues are the development of nonvolatile optical reconfiguration techniques which are compatible with on‐chip integration with different photonic platforms and do not disrupt their optical performances. Herein, a solution is demonstrated using an optoelectronic framework for nonvolatile tunable photonics that uses undoped‐graphene microheaters to thermally and reversibly switch the optical phase‐change material Ge2Sb2Se4Te1 (GSST). An in situ Raman spectroscopy method is utilized to demonstrate, in real‐time, reversible switching between four different levels of crystallinity. Moreover, a 3D computational model is developed to precisely interpret the s...

UV-Laser interactions with wide bandgap insulators and semiconductors has generated a number of examples of point defect production, surface and bulk modification, etching and re-deposition processes, as well as numerous PLD related applications involving the emitted particles. In this talk we examine these phenomena and modifications in oriented single crystals of the transparent semiconductor ZnO which as a band-gap of ~3.4 eV. This material is of high interest for production of transparent conductors and transistors, solar cells, lasers, sensors, and in catalysis (including potential use in the photo-dissociation of water). We explore exposure of single crystal ZnO to UV laser radiation under ultra high vacuum conditions. We examine the underlying mechanisms for nanoparticle growth on the exposed surface, the emissions of ions, the intense and energetic emissions of neutral Zn, O, and O 2 , and the extraordinary clean etching of this very brittle but highly important technological material.

The present paper is a first feasibility study for the SONOLINO project which aims at developing a new method of in-situ diagnostics for the characterization of combustion nanoparticle structure in aerosol phase by using their non-linear optical behavior.

The project’s results will provide a new understanding about the particles’ maturity and composition and will thus in the long-term help to analyze air quality and particle toxicity and to reduce the production of air pollutants.

 The coupled electronic states in two-dimensional (2D) and three-dimensional (3D) double quantum dot (DQD) systems are investigated using a phenomenological model applied to InAs/GaAs heterostructures. The single-band k . p effective potential approach previously proposed by our group is employed to numerically calculate the energy spectrum and spatial localization of a single electron, serving as an indicator of the coupling strength within the binary system. For identical quantum dots (QDs) in a DQD, the electronic states exhibit ideal coherence. We systematically vary the DQD geometry and the strength of the confinement potential (via an applied electric field)to examine the effects of symmetry breaking and the sensitivity of electron localization in both identical and nearly identical DQDs. Our results show that coherence in DQDs is highly sensitive to these subtle variations. This sensitivity can be harnessed to detect changes in the surrounding environment, such as fluctuations in chemical or electrical properties that affect the DQD system.

An SDN-enabled modular photonic system architecture, including VCSEL-based bandwidth/bitrate variable transceivers, for multi-terabit capacity transmission and agile spectrum/space switching in optical metro networks is presented, providing the proposed technological solutions, programmability aspects and preliminary assessment.

Many research papers on optical interconnects have been published over the last three decades, however, some models are oversimplified and overlooked important design considerations. These include the timing synchronization of the VCSEL sources; detailed calculations of the free space optoelectronic interconnect network, theoretical analysis of computer generated hologram on optical interconnect system. An example of detailed analysis are presenting here for devising optoelectronic interconnect switching network based on a banyan switch. In order to expand the work into a large optoelectronic switching arrays, more careful considerations may be necessary from system perspective..

Interconnection networks must transport an always increasing information density and connect a rising number of processing units. Electronic technologies have been able to sustain the traffic growth rate, but are getting close to their physical limits. In this context, optical interconnection networks are becoming progressively more attractive, especially because new photonic devices can be directly integrated in CMOS technology. Indeed, interest in microring resonators as switching components is rising, but their usability in full optical interconnection architectures is still limited by their physical characteristics. Indeed, differently from classical devices used for switching, switching elements based on microring resonators exhibit asymmetric power losses depending on the output ports input signals are directed to. In this paper, we study classical interconnection architectures such as crossbar, Benes and Clos networks exploiting microring resonators as building blocks. Since classical interconnection networks lack either scalability or complexity, we propose two new architectures to improve performance of microring based interconnection networks while keeping a reasonable complexity.

The IST-LASAGNE project aims at designing and implementing the first, modular, scalable and truly all-optical photonic router capable of operating at 40 Gb/s. The main results achieved in the project are presented in this paper, with emphasis on the implementation of network node functionalities employing optical logic gates and optical flip-flops, as well as an economical study on the proposed all-optical node architecture. Experimental results on clock recovery, packet-rate clock recovery and 2-bit label reading are provided employing optical gates based on active Mach-Zehnder interferometers as the basic building block. The obtained results are very promising towards the goal of building an all-optical photonic router for label-swapping networks.

We demonstrate 4 × 4 and 8 × 8 switch fabrics in multistage topologies based on 2 × 2 Mach-Zehnder interferometer switching elements. These fabrics are integrated onto a single chip with digital CMOS logic, device drivers, thermo-optic phase tuners, and electro-optic phase modulators using IBM's 90 nm silicon integrated nanophotonics technology. We show that the various switch-and-driver systems are capable of delivering nanosecondscale reconfiguration times, low crosstalk, compact footprints, low power dissipations, and broad spectral bandwidths. Moreover, we validate the dynamic reconfigurability of the switch fabric changing the state of the fabric using time slots with sub-100-ns durations. We further verify the integrity of high-speed data transfers under such dynamic operation. This chip-scale switching system technology may provide a compelling solution to replace some routing functionality currently implemented as bandwidth-and power-limited electronic switch chips in high-performance computing systems.

We propose a new design scheme of resilient Wavelength Division Multiplexing (WDM) networks by extending and reshaping pre-configured protection tree (p-tree) structures. The resulting protection scheme relies on optimized pre-cross connected structures that span all previously proposed protection patterns. p-Tree-based protection schemes offer the advantages of scalability, local restoration capabilities, and failure impact restriction, but at the same time suffers from capacity inefficiency. While keeping these advantages, we propose an extension (reshaping) of the p-tree protection pattern that imposes no restriction on the shapes of the protection building blocks. Not only the resulting protection scheme remains scalable and highly flexible, but it also leads to pre-configured protection structures that improve much further on capacity efficiency and recovery delay. We establish some new integer linear programming models, and use large scale optimization tools, namely column generation (CG) to solve them. Our CG-based solution method is highly scalable as it does not require an a priori explicit enumeration of the protection structures, but an efficient dynamic enumeration of only the most promising ones. Comparison are made with three other protection schemes, i.e, simple and non-simple p-cycles (fully pre-cross connected structures) as well as p-trees. Results show a clear advantage of the proposed extended-tree scheme with respect to flexibility, capacity efficiency, and restoration delay.

Based on a microscopic many-particle theory we study the amplification of polaritons in a multiple-quantum-well resonant photonic crystal. For the Bragg-spaced multiple quantum wells under investigation we predict that in a typical pump-probe setup four-wave mixing processes can lead to an unstable energy transfer from the pump into the probe and the background-free four-wave mixing directions. We find that under certain excitation conditions this phase-conjugate oscillation induced instability can lead to a large amplification of the weak probe pulse.

Volume-phonon-polaritons (VPP’s) propagating at a light-in-vacuum-like speed are identified in the wurtzite-type Zn0.74Mg0.26Se mixed crystal by near-forward Raman scattering. Their detection is selective to both the laser energy and the laser polarization, depending on whether the ordinary (n0) or extraordinary (ne) refractive index is addressed. Yet, no significant linear birefringence (n0 $${\boldsymbol{\simeq }}$$ ≃  ne) is observed by ellipsometry. The current access to ultrafast VPP’s is attributed to the quasi-resonant Raman probing of an anomalous dispersion of n0 due to impurity levels created deep in the optical band gap by oriented structural defects. The resonance conditions are evidenced by a dramatic enhancement of the Raman signals due to the polar modes. Hence, this work reveals a capacity for the lattice defects’ engineering to “accelerate” the VPP’s of a mixed crystal up to light-in-vacuum-like speeds. This is attractive for ultrafast signal processing in the terah...

We present a theoretical study of Coulomb exchange interaction for electrons confined in a cylindrical quantum wire and subject to a Rashba-type spin-orbit coupling with radial electric field. The effect of spin splitting on the single-particle band dispersions, the quasiparticle effective mass, and the system's total exchange energy per particle are discussed. Exchange interaction generally suppresses the quasiparticle effective mass in the lowest nanowire subband, and a finite spin splitting is found to significantly increase the magnitude of the quasiparticle-mass suppression (by upto 15% in the experimentally relevant parameter regime). In contrast, spin-orbit coupling causes a modest (1%-level) reduction of the magnitude of the exchange energy per particle. Our results shed new light on the interplay of spin-orbit coupling and Coulomb interaction in quantum-confined systems, including those that are expected to host exotic quasiparticle excitations.

Exciton-polaritons are hybrid light-matter states that arise from strong coupling between an exciton resonance and a photonic cavity mode. As bosonic excitations, they can undergo a phase transition to a condensed state that can emit coherent light without a population inversion. This aspect makes them good candidates for thresholdless lasers, yet short exciton-polariton lifetime has made it difficult to achieve condensation at very low power densities. In this sense, long-lived symmetry-protected states are excellent candidates to overcome the limitations that arise from the finite mirror reflectivity of monolithic microcavities. In this work we use a photonic symmetry protected bound state in the continuum coupled to an excitonic resonance to achieve state-of-theart polariton condensation threshold in GaAs/AlGaAs waveguide. Most important, we show the influence of fabrication control and how surface passivation via atomic layer deposition provides a way to reduce exciton quenching at the grating sidewalls.

We analyze the extended wavelength photoresponse beyond the standard threshold limit ( / . t 24 1 , where is the activation energy) in non-symmetrical p-GaAs/AlGaAs heterostructure photodetectors with a barrier energy offset. We propose that hot-cold hole carrier interactions in the p-GaAs absorber are responsible for the threshold wavelength extension. Experimental results are analyzed by considering a quasi-Fermi distribution of hot holes at a hot hole temperature H T , which is much higher than the lattice temperature L T . The experimental photoresponse is fitted using an escape cone model, modified with a quasi-Fermi level (EquasiF). The simulated results are found to be in good agreement with experimental data, justifying the model used.

This paper deals with optical packet switching in a full-IP transport network scenario. Given the technological limits of accomplishing packet buffering in the optical domain, deflection routing is here explored as an alternative technique for resolving packet contentions without buffering packets. Two different network topologies have been considered here, that is a regular six-node network with different connectivity factors and the classical NSF network. A limited amount of optical buffering is considered in the switching nodes that performs both input queuing and shared queuing of packets to be switched. The performance improvements that can be obtained by deflection routing have been evaluated considering different methods for choosing the alternative paths where to deflect packets that cannot be transmitted onto the shortest path to the addressed destination.

The asynchronous transfer mode ͑ATM͒ is a promising technique for broadband switching that is capable of supporting high-bit-rate multimedia services. Progress in all-optical parallel processing shows that photonics may be used in the future in full-functionality ATM switching nodes. All-optical switching fabrics and buffers have already been demonstrated. Fewer studies have been dedicated to ATM header-processing functions. As an example of photonic header processing, the implementation of a header-error control ͑HEC͒ subsystem by means of an optical circuit is investigated. Although traditional electronic decoders perform HEC in a serial mode, the architecture chosen for the optical HEC subsystem is based on parallelism, and an appropriate parallel-decoding algorithm was used in designing it.

This paper describes the first experiment on Multi-Rail and MultiLane technologies using global networks. These technologies leverage end-host and network parallel resources, e.g., processor cores and lambda paths, to achieve large bandwidths.

I propose combining of all-optical devices to produce an all-optical device that exhibits a desired input-output (I/ O) characteristic (i.e., a desired functionality). There could be infinite distinct combinations of same/different all-optical devices of same/different parameters resulting in possibility of infinite number of all-optical devices with distinct I/O characteristics, and hence, the proposal presented here opens-up a gateway to synthesis of alloptical devices of desired functionalities. To give a few of examples in support of the proposal, I show certain series and parallel combinations of nonlinear Mach-Zehnder interferometers (NMZIs) to synthesize an (i) ideal optical switch (with step like I/O characteristic), (ii) optical isolator/optical stabilizer (iii) optical pulse generator (iv) optical power filter and (v) optical limiter. The analytical findings are verified using BPM simulations in presence of losses also.

We demonstrate a ferroelectric optical device based on single crystal LiTaO 3 that can scan a laser beam from the visible to the infrared. It utilizes the electro-optic effect in the ferroelectric that has potentially high intrinsic response times of GHz. There are many applications to such scanning devices in the infrared such as optical switching, spectrometry, microscopy, and sensing. Lithium tantalate has two ferroelectric polarization states that are antiparallel (180û) to each other. The domain states can be reversed by applying an electric field of ~21 kV/mm at room temperature. By reversing the domain structure in the crystal, we can create domains in the crystal of almost any desired shape. By creating prism-shaped domain, we can create a ferroelectric deflector or scanner by applying either static or sweeping voltages across the crystal. This scanner is capable of scanning wavelengths from 0.4-5 µm. The scanning performance varied from a total deflection angle of 13.38° at 1558 nm to 16.18° at 632.8 nm. Since the amount of deflection of the incoming light is determined by the applied voltage, the electro-optic coefficient and other fixed quantities, by measuring the deflection angle as a function of wavelength, the dispersion of the electro-optic coefficient in lithium tantalate can be determined. In these experiments, the scanner was characterized from the visible (632.8 nm) to midinfrared (1558 nm). Both extraordinary and the ordinary polarizations of light were used, in order to determine the electro-optic coefficients, r 33 and r 31 . Except for the values at 632.8 nm, these values of the electro-optic coefficients have not been previously reported. For lithium tantalate, r 33 at 632.8 nm is reported in the literature as 30.2 pm/V. We found that this decreases to 27.1 pm/V at 1558 nm. For the extraordinary polarization, r 13 varied from 7.55 pm/V (632.8 nm) to 6.84 pm/V (1558 nm).

A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs' switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed.

A technique of impurity-free vacancy-induced disordering of GaAs/AlGaAs multiquantum wells (MQW) that is area selective, very reliable, and highly reproducible, has been developed. The localized compositional disordering is induced by rapid thermal annealing of the sample after it has been coated with a thin film of ‘‘spin-on’’ glass and prebaked at 400 °C in a high purity nitrogen:oxygen (78:22) atmosphere. In order to self-consistently determine the diffusion coefficient of the Al and Ga atoms, the photoluminescence peak is fitted to the n=1 electron to heavy hole transition that corresponds to an error function potential profile caused by the diffusion. The process has been used to integrate two optical devices on a MQW structure. One is a nonlinear directional coupler all-optical switch, and the other is an integrated Mach–Zehnder all-optical modulator. The switching characteristics of the devices were measured using the conventional pump-probe measurement technique.

This paper proposes KAR (Key-for-Any-Route), a new intra-domain resilient routing system in which edge-nodes set a route ID to select any existing route as an alternative to safely forward packets to their destination. In KAR routing system, a route is defined as the remainder of the division between a route ID and a set of switch IDs along the path(s) between a pair of nodes. KAR-enabled switches explore the existing routes by using special properties of Residue Number System as our encoding technique. Packets are deviated from the faulty link (liveness condition) with routing deflections. Deflected packets are guided to their original destination due to resilient forwarding paths added to the route ID. Three deflection methods are discussed along emulation experiments. Results show that KAR efficiently allows deflected packets to automatically reach their destination, imposing a bound on packets disordering measured in TCP throughput.

This paper contains some interesting experimental results of the study carried out on anomalous spectral behavior due to coherence and polarization change on polychromatic focused dark hollow Gaussian beam (DHGB). On the basis of experimental and numerical analysis, the possibility and significance of DHGB based free-space optical (FSO) links for indoor and outdoor optical communications are explored.

We describe the design of an optical switch in the chaperonin GroEL that is opened and closed by its ATP-and cochaperonin GroES-driven conformational changes. The switch, based on a fluorophore and a quencher, is engineered into the single-ring variant of the chaperone, and shows dramatic modulation of its fluorescent intensity in response to the transition of the protein between its allosteric states. It, therefore, forms a sensitive probe for the dynamics of the allosteric transitions of this machine, both in the bulk and in single molecules.

We demonstrate path wavelength routing and switching using a packaged and pigtailed hybrid integrated silicon-on-insulator (SOI) photonic circuit. The fabricated device incorporates a 1.25 mm nonlinear semiconductor optical amplifier mounted on the SOI board and two multimode interference-based cascaded delay interferometers monolithically integrated on the same SOI substrate. The photonic chip has a footprint of 384 mm and performs all-optical wavelength conversion at ultrafast data rates. The packaged and pigtailed module is inserted and tested as a switching node in a meshed optical network testbed carrying real data traffic and encompassing a wavelength division multiplexing optical link. Optical path wavelength switching and routing is implemented by a generalized multiprotocol label switching control plane. We present 10 GbE video-streaming routing as well as 40 Gb/s wavelength switching employing the system integrated all-optical wavelength converter. Error-free transmission and different kind of end-to-end services (video distribution, audio conference, and video conference) have been successfully evaluated.