Showing papers on "Optical switch published in 2011"

On-chip optical isolation in monolithically integrated non-reciprocal optical resonators

Abstract: Scientists report the fabrication of a nonreciprocal optical resonator with a small length footprint of 290 µm on a silicon-on-insulator substrate. The device achieves unidirectional optical transmission with an isolation ratio of up to 19.5 dB near the telecommunications wavelength of 1,550 nm in a homogeneous external magnetic field.

Advanced continuous analyte monitoring system

Abstract: Systems and methods for processing, transmitting, and displaying data received from a continuous analyte (e.g., glucose) sensor are provided. A sensor system can comprise a sensor electronics module that includes power saving features, e.g., a low power measurement circuit that can be switched between a measurement mode and a low power mode, wherein charging circuitry continues to apply power to electrodes of a sensor during the low power mode. The sensor electronics module can be switched between a low power storage mode and a higher power operational mode via a switch, e.g., a reed switch or optical switch. A validation routine can be implemented to ensure an interrupt signal sent from the switch is valid. The sensor can be physically connected to the sensor electronics module in direct wireless communication with a plurality of different display devices.

Liquid-crystal photonic applications

Abstract: Liquid crystals are nowadays widely used in all types of display applications. However their unique electro-optic properties also make them a suitable material for nondisplay applications. We will focus on the use of liquid crystals in different photonic components: optical filters and switches, beam-steering devices, spatial light modulators, integrated devices based on optical waveguiding, lasers, and optical nonlinear components. Both the basic operating principles as well as the recent state-of-the art are discussed.

Induced transparency in nanoscale plasmonic resonator systems.

Abstract: An optical effect analogous to electromagnetically induced transparency (EIT) is observed in nanoscale plasmonic resonator systems. The system consists of a slot cavity as well as plasmonic bus and resonant waveguides, where the phase-matching condition of the resonant waveguide is tunable for the generation of an obvious EIT-like coupled resonator-induced transparency effect. A dynamic theory is utilized to exactly analyze the influence of physical parameters on transmission characteristics. The transparency effect induced by coupled resonance may have potential applications for nanoscale optical switching, nanolaser, and slow-light devices in highly integrated optical circuits.

Ultralow Power Silicon Photonics Thermo-Optic Switch With Suspended Phase Arms

Abstract: In this letter, a 2 × 2 thermo-optic waveguide-based switch with ultralow power consumption is demonstrated and fabricated using a standard complementary metal-oxide-semi conductor (CMOS) process. The phase arms are suspended by removing adjacent SiO2 and 120 μm of the underlying Si, while leaving a few SiO2 beams to support the suspended phase arms for the purpose of structural strength. As compared to the switch without isolation layer, a significant reduction of >;98% in power consumption is achieved. It is realized by preventing the heat from leaking out of the phase arms due to the presence of the air isolation layer. Our device shows an extinction ratio of over 23 dB at 1550 nm for TE mode with an ultralow power consumption of 0.49 mW. The response time is 266 μs, including the raise time of 144 μs and the fall time of 122 μs.

Non-Blocking 4x4 Electro-Optic Silicon Switch for On-Chip Photonic Networks

Abstract: We present a 4x4 spatially non-blocking Mach-Zehnder based silicon optical switch fabricated using processes fully compatible with standard CMOS. We successfully demonstrate operation in all 9 unique switch states and 12 possible I/O routing configurations, with worst-case cross-talk levels lower than −9 dB, and common spectral bandwidth of 7 nm. High-speed 40 Gbps data transmission experiments verify optical data integrity for all input-output channels.

The emerging optical data center

Abstract: We review the architecture of modern datacenter networks, as well as their scaling challenges; then present high-level requirements for deploying optical technologies in datacenters, particularly focusing on optical circuit switching and WDM transceivers.

Bandwidth Squeezed Restoration in Spectrum-Sliced Elastic Optical Path Networks (SLICE)

Abstract: With the continuing growth in the amount of backbone traffic, improving the cost-effectiveness and ensuring survivability of the underlying optical networks are very important problems facing network service providers today. In this paper, we propose a bandwidth squeezed restoration (BSR) scheme in our recently proposed spectrum-sliced elastic optical path network (SLICE). The proposed BSR takes advantage of elastic bandwidth variation in the optical paths of SLICE. It enables spectrally efficient and highly survivable network recovery for best-effort traffic as well as bandwidth guaranteed traffic, while satisfying the service level specifications required from the client layer networks. We discuss the necessary interworking architectures between the optical path layer and client layer in the BSR in SLICE. We also present a control framework that achieves flexible bandwidth assignment as well as BSR of optical paths in SLICE. Finally, we describe an implementation example of a control plane using generalized multi-protocol label switching (GMPLS).

Spectrally Efficient Long-Haul WDM Transmission Using 224-Gb/s Polarization-Multiplexed 16-QAM

Abstract: We discuss the generation, wavelength-division-multiplexed (WDM) long-haul transmission, and coherent detection of 224-Gb/s polarization-division-multiplexed (PDM) 16-ary quadrature amplitude modulation (16-QAM) at a line rate of 28 Gbaud. We measure a required optical signal-to-noise ratio of 23.4 dB (0.1-nm reference bandwidth; 10-3 bit-error ratio), 3.4-dB off the theoretical limit. Using ultra-large-area fiber, we achieve 2000-km single-channel transmission. We also demonstrate 1200-km WDM transmission on a 50-GHz grid (4-b/s/Hz spectral efficiency), including three passes through a wavelength-selective switch.

Theoretical and experimental investigation of all-optical switching based on cascaded LPFGs separated by an erbium-doped fiber

Abstract: A new all-optical switching device, which is constructed by connecting an erbium-doped fiber with two symmetrical long-period fiber gratings (EDF-LPFGs), is demonstrated. The performance of EDF-LPFGs switching has been investigated based on cross-phase modulation under different parameters. The theoretical analysis shows that the threshold switching power is inverse proportional to the nonlinear coefficient of the erbium-doped fiber, and is proportional to the effective area of the erbium-doped fiber and absorption coefficient. Moreover, the switching power as low as 36 mW and high extinction ratio of 18 dB are obtained in our experiment. Good agreement between the theoretical and experimental results indicate that EDF-LPFGs switching is a new design in support of switching power reduction.

Progress in Low-Power Switched Optical Interconnects

Abstract: Optical links have successfully displaced electrical links when their aggregated bandwidth-distance product exceeds ~100 Gb/s-m because their link energy per bit per unit distance is lower. Optical links will continue to be adopted at distances of 1 m and below if link power falls below 1 pJ/bit/m. Providing optical links directly to a switching/routing chip can significantly improve the switched energy/bit. We present an early experimental switched CMOS-vertical-cavity surface-emitting laser (VCSEL) system operating at Gigabit Ethernet line rates that achieves a switched interconnect energy of less than 19 pJ/bit for a fully nonblocking network with 16 ports and an aggregate capacity of 20 Gb/s/port. The CMOS-VCSEL switch achieves an optical bandwidth density of 37 Gb/s/mm2 even when operating at a modest line rate of 1.25 Gb/s and is capable of scaling to much higher peak bandwidth densities (~350 Gb/s/mm2) with 5-10 pJ/switched bit. We also review a silicon photonic system design that will lower link energies to 300 fJ/bit, while providing multiterabits per second per square millimeter bandwidth densities. This system will ultimately provide switched optical interconnect at less than a picojoule per switched bit and computer/router system energies of tens of picojoule per bit. We review progress made to date on the silicon photonic components and analyze an energy and bandwidth-density roadmap for future advances toward these goals.

Electrowetting driven optical switch and tunable aperture

Abstract: We demonstrate an electrowetting based optical switch with tunable aperture. Under the influence of an electric field a non-transparent oil film can be replaced locally by a transparent water drop creating an aperture through which light can pass. Its diameter can be tuned between 0.2 and 1.2 mm by varying the driving voltage or frequency. The on and off response time of the switch is in the order of 2 and 120 ms respectively. Finally we demonstrate an array of switchable apertures that can be tuned independently or simultaneously.

Integrated OpenFlow — GMPLS control plane: An overlay model for software defined packet over optical networks

Abstract: A novel software-defined packet over optical networks solution based on the OpenFlow and GMPLS control plane integration is demonstrated. The proposed architecture, experimental setup, and average flow setup time for different optical flows is reported.

Flexible and grid-less wavelength selective switch using LCOS technology

Abstract: The increasing spectral efficiency of Optical Transmission systems is constrained by the limitations of wavelength switching and is driving a requirement for significantly more flexible approaches to routing of the optical traffic. We present the intrinsic Grid-free capabilities of LCOS and show how it can be used practically in a flexible Grid architecture to maximize total fiber capacity.

Large Port Count High-Speed Optical Switch Fabric for Use Within Datacenters [Invited]

Abstract: This paper reviews advances in the technology of integrated semiconductor optical amplifier based photonic switch fabrics, with particular emphasis on their suitability for high performance network switches for use within a datacenter. The key requirements for large port count optical switch fabrics are addressed noting the need for switches with substantial port counts. The design options for a 16 × 16 port photonic switch fabric architecture are discussed and the choice of a Clos-tree design is described. The control strategy, based on arbitration and scheduling, for an integrated switch fabric is explained. The detailed design and fabrication of the switch is followed by experimental characterization, showing net optical gain and operation at 10 Gb/s with bit error rates lower than 10-9. Finally improvements to the switch are suggested, which should result in 100 Gb/s per port operation at energy efficiencies of 3 pJ/bit.

Microring-resonator-based four-port optical router for photonic networks-on-chip

Abstract: We design and fabricate a four-port optical router, which is composed of eight microring-resonator-based switching elements, four optical waveguides and six waveguide crossings. The extinction ratio is about 13 dB for the through port and larger than 30 dB for the drop port. The crosstalk of the measured optical links is less than -13 dB. The average tuning power consumption is about 10.37 mW and the tuning efficiency is 5.398 mW/nm. The routing functionality and optical signal integrity are verified by transmitting a 12.5 Gb/s PRBS optical signal.

The role of optics in future high radix switch design

Abstract: For large-scale networks, high-radix switches reduce hop and switch count, which decreases latency and power. The ITRS projections for signal-pin count and per-pin bandwidth are nearly flat over the next decade, so increased radix in electronic switches will come at the cost of less per-port bandwidth. Silicon nanophotonic technology provides a long-term solution to this problem. We first compare the use of photonic I/O against an all-electrical, Cray YARC inspired baseline. We compare the power and performance of switches of radix 64, 100, and 144 in the 45, 32, and 22 nm technology steps. In addition with the greater off-chip bandwidth enabled by photonics, the high power of electrical components inside the switch becomes a problem beyond radix 64. We propose an optical switch architecture that exploits highspeed optical interconnects to build a flat crossbar with multiplewriter, single-reader links. Unlike YARC, which uses small buffers at various stages, the proposed design buffers only at input and output ports. This simplifies the design and enables large buffers, capable of handling ethernet-size packets. To mitigate head-of-line blocking and maximize switch throughput, we use an arbitration scheme that allows each port to make eight requests and use two grants. The bandwidth of the optical crossbar is also doubled to to provide a 2x internal speedup. Since optical interconnects have high static power, we show that it is critical to balance the use of optical and electrical components to get the best energy efficiency. Overall, the adoption of photonic I/O allows 100,000 port networks to be constructed with less than one third the power of equivalent all-electronic networks. A further 50% reduction in power can be achieved by using photonics within the switch components. Our best optical design performs similarly to YARC for small packets while consuming less than half the power, and handles 80% more load for large message traffic.

High gain ultraviolet photodetectors based on AlGaN/GaN heterostructures for optical switching

Abstract: We report on the optoelectronic properties of Al0.25Ga0.75N/GaN-based ultraviolet (UV) photodetectors for the application as a high current, high gain optical switch. Due to an internal gain mechanism combined with the high conductivity of the two-dimensional electron gas at the heterostructure interface, photocurrents in the milliampere-range were obtained with UV illumination. By employing a mesa structure design with meander geometry very low dark currents below 50 nA up to a bias voltage of 100 V were achieved. Optical switching with an on/off-current-ratio of five orders of magnitude was demonstrated. The response time was determined to be 6 ms and persistent photoconductivity was observed. The photodetector is visible-blind with a cut-off wavelength of 365 nm according to the band gap energy of the GaN absorption layer. A high responsivity with a maximum of 70 A/mW at 312 nm and 100 V bias voltage was demonstrated.

All-optical switching of a single resonance in silicon ring resonators.

Abstract: We theoretically investigate a wavelength-selective all-optical switch using Raman-induced loss in a silicon resonator add–drop filter. We show that picojoule control pulses can selectively modulate and “erase” a single cavity resonance from full extinction to greater than 97% transmission while leaving adjacent resonances undisturbed. Full switching is achievable in less than 300 ps with only a few hundred femtojoule energy dissipation. This represents, to our knowledge, the first scheme for selective modulation of single resonances of an optical cavity.

Complex Faraday rotation in microstructured magneto-optical fiber waveguides.

Abstract: Magneto-optical glasses are of considerable current interest, primarily for applications in fiber circuitry, optical isolation, all-optical diodes, optical switching and modulation. While the benchmark materials are still crystalline, glasses offer a variety of unique advantages, such as very high rare-earth and heavy-metal solubility and, in principle, the possibility of being produced in fiber form. In comparison to conventional fiber-drawing processes, pressure-assisted melt-filling of microcapillaries or photonic crystal fibers with magneto-optical glasses offers an alternative route to creating complex waveguide architectures from unusual combinations of glasses. For instance, strongly diamagnetic tellurite or chalcogenide glasses with high refractive index can be combined with silica in an all-solid, microstructured waveguide. This promises the implementation of as-yet-unsuitable but strongly active glass candidates as fiber waveguides, for example in photonic crystal fibers.

Broadband Silicon Photonic Electrooptic Switch for Photonic Interconnection Networks

Abstract: We present a silicon photonic microring resonator electrooptic switch, demonstrate error-free switching of single-channel data rates up to 40 Gb/s, and characterize the device using bit-error-rate and power penalty metrics. We experimentally verify penalty-free switching of single-channel data rates up to 10 Gb/s, and low-penalty switching up to 40 Gb/s, firmly establishing the feasibility of this switch for high-performance photonic networks-on-chip.

Traffic grooming in Spectrum-Elastic Optical Path Networks

Abstract: We propose a novel approach of traffic grooming in Spectrum-Elastic Optical Path Networks. Higher spectrum efficiency is achieved by our approach comparing with non-traffic-grooming scenario.

Reducing Power Consumption in Wavelength Routed Networks by Selective Switch Off of Optical Links

Abstract: In this paper, the power consumption of a transparent circuit-switched wavelength-division multiplexing (WDM) optical network is evaluated, considering client flow protection requirements and the daily traffic variability. Moreover, a simple heuristic algorithm is applied to the considered network scenario to reduce the power consumption of optical links. When traffic load decreases, the algorithm tries to switch off optical links according to several heuristic criteria that take into account the power consumption parameter of links, some topological consideration and the congestion of each fiber. By performing such an optimization, applying the best link-ordering criterion, it is possible to save an amount of power from 28% up to 86% of the power consumed by optical links on the basis of the traffic load. This leads to an average energy saving of 35% with respect to the energy consumed by the whole optical network. Moreover, we evaluate the impact of network design parameters on the proposed algorithm and the network power consumption. Results show that, for a 18-node network supporting an average traffic of 75 Gbits/s between each node pair, a number of wavelengths equal to 80 can drastically reduce the power consumption of optical links.

Power management of optoelectronic interfaces for dynamic optical networks

Abstract: We propose a protocol enhancement to manage the power state of optoelectronic interfaces in automatically reconfigurable optical networks. For dynamic traffic scenarios 67% of energy savings have been estimated for the optoelectronic interfaces.

Experimental realization of a low-noise heralded single-photon source

Abstract: We present a heralded single-photon source with a much lower level of unwanted background photons in the output channel by using the herald photon to control a shutter in the heralded channel. The shutter is implemented using a simple field programable gate array controlled optical switch.

A 2×2 spatial optical switch based on PT-symmetry.

Abstract: We show a PT-symmetric coupler having an arm with a tunable gain and a no-loss arm when appropriately designed to possess reciprocal behavior, unlike its rivals having a fixed gain/loss arm, can perform as a tunable 2×2 spatial optical switch. The degree of the tunability equals the ratio of the coupler’s length to the total coupling length.

Pneumatically tunable optofluidic 2 × 2 switch for reconfigurable optical circuit

Abstract: We presented a pneumatically tunable 2 × 2 optofluidic switch for on-chip light routing that was controlled by compressed air. The device was fabricated with an optically clear elastomer—polydimethylsiloxane (PDMS)—by soft-lithography. The optical switching is realized with a tunable air-gap mirror by which the light is deflected due to total internal reflection in the bypass state. When the device is subjected to high pressure, the air gap collapses and hence the light will be switched to the crossover state. The device had a switching speed of more than 5 Hz and an extinction ratio of 8 dB. This switch can be readily integrated with other microfluidic circuits. We demonstrated a simple reconfigurable optical waveguide circuit for dual-channel microfluidic spectroscopy measurement on a chip.

Experimental demonstration of 400 Gb/s multi-flow, multi-rate, multi-reach optical transmitter for efficient elastic spectral routing

Abstract: We demonstrate a multi-flow/multi-rate/multi-reach optical transmitter and spectral routing of total 400 Gb/s optical flows. The number of optical flows, bit rate, and optical reach can be adjusted to enable efficient elastic spectral routing.

Architecture on demand for transparent optical networks

Abstract: We present the Architecture on Demand (AoD) concept whereby transparent optical cross-connects (OXC) do not have an associated static architecture but can adapt their architecture to suit to the switching and processing requirements of input traffic. The proposed AoD-OXC is implemented with a 96×96 3D-MEMS optical switch functioning as an optical backplane that interconnects architecture-building modules that provide the required services such as arbitrary spectrum switching, time-domain sub-wavelength switching and optical multicasting. This approach will enable unprecedented levels of flexibility and modularity for the introduction of new services and applications in transparent optical networks.