Showing papers on "Optical switch published in 2010"

Helios: a hybrid electrical/optical switch architecture for modular data centers

Abstract: The basic building block of ever larger data centers has shifted from a rack to a modular container with hundreds or even thousands of servers. Delivering scalable bandwidth among such containers is a challenge. A number of recent efforts promise full bisection bandwidth between all servers, though with significant cost, complexity, and power consumption. We present Helios, a hybrid electrical/optical switch architecture that can deliver significant reductions in the number of switching elements, cabling, cost, and power consumption relative to recently proposed data center network architectures. We explore architectural trade offs and challenges associated with realizing these benefits through the evaluation of a fully functional Helios prototype.

Sub-femtojoule all-optical switching using a photonic-crystal nanocavity

Abstract: Although high-speed all-optical switches are expected to replace their electrical counterparts in information processing, their relatively large size and power consumption have remained obstacles. We use a combination of an ultrasmall photonic-crystal nanocavity and strong carrier-induced nonlinearity in InGaAsP to successfully demonstrate low-energy switching within a few tens of picoseconds. Switching energies with a contrast of 3 and 10 dB of 0.42 and 0.66 fJ, respectively, have been obtained, which are over two orders of magnitude lower than those of previously reported all-optical switches. The ultrasmall cavity substantially enhances the nonlinearity as well as the recovery speed, and the switching efficiency is maximized by a combination of two-photon absorption and linear absorption in the InGaAsP nanocavities. These switches, with their chip-scale integratability, may lead to the possibility of low-power, high-density, all-optical processing in a chip. All-optical switching energies as small as 0.42 fJ — two orders of magnitude lower than previously reported — are demonstrated in small photonic crystal cavities incorporating InGaAsP. These devices can switch within a few tens of picoseconds, and may therefore have potential for low-power high-density all-optical processing on a chip.

Flexible architectures for optical transport nodes and networks

Abstract: Flexibility to support mesh topologies, dynamic capacity allocation, and automated network control and light path setup are key elements in the design of next-generation optical transport networks. To realize these capabilities, reconfigurable optical add/drop multiplexers with dynamic add/drop structures, embedded control planes, and lightpath characterization are required. This article presents the architectures and various ROADM implementations including colorless, directionless, and contentionless add/drop structures. The effect of scaling bit rates beyond 100 Gb/s on ROADM architectures is reviewed including providing variable channel bandwidth depending on bit rate. Automated provisioning and restoration using the GMPLS control plane and optical measurement approaches for lightpaths are also discussed.

An ultra-small, low power all-optical flip-flop memory on a silicon chip

Abstract: Ultra-small, low-power, all-optical switching and memory elements, such as all-optical flip-flops, as well as photonic integrated circuits of many such elements, are in great demand for all-optical signal buffering, switching and processing. Silicon-on-insulator is considered to be a promising platform to accommodate such photonic circuits in large-scale configurations. Through heterogeneous integration of InP membranes onto silicon-on-insulator, a single microdisk laser with a diameter of 7.5 µm, coupled to a silicon-on-insulator wire waveguide, is demonstrated here as an all-optical flip-flop working in a continuous-wave regime with an electrical power consumption of a few milliwatts, allowing switching in 60 ps with 1.8 fJ optical energy. The total power consumption and the device size are, to the best of our knowledge, the smallest reported to date at telecom wavelengths. This is also the only electrically pumped, all-optical flip-flop on silicon built upon complementary metal-oxide semiconductor technology. Scientists demonstrate that a single 7.5-μm-diameter microdisk laser coupled to a silicon-on-insulator wire waveguide can work as an all-optical flip-flop memory. Under a continuous bias of 3.5 mA, flip-flop operation is demonstrated using optical triggering pulses of 1.8 fJ and with a switching time of 60 ps. This device is attractive for on-chip all-optical signal buffering, switching, and processing.

Adaptive Current Regulation for Solid State Lighting

Abstract: Exemplary embodiments provide an apparatus, system and method for power conversion to provide power to solid state lighting, and which may be coupled to a first switch, such as a dimmer switch. An exemplary system comprises: a switching power supply; solid state lighting; a first adaptive interface circuit to provide a resistive impedance to the first switch and conduct current from the first switch in a default mode; and a second adaptive interface circuit to create a resonant process. An exemplary apparatus comprises: a switching power supply; and an adaptive interface circuit comprising a resistive impedance coupled in series to a reactive impedance to conduct current from the first switch in a first current path in a default mode, and further comprising a second switch coupled to the reactive impedance to conduct current from the first switch in a second current path, with the adaptive interface circuit further damping oscillation when the first switch turns on.

Design of Polymethine Dyes with Large Third-Order Optical Nonlinearities and Loss Figures of Merit

Abstract: All-optical switching applications require materials with large third-order nonlinearities and low nonlinear optical losses. We present a design approach that involves enhancing the real part of the third-order polarizability (γ) of cyanine-like molecules through incorporation of polarizable chalcogen atoms into terminal groups, while controlling the molecular length to obtain favorable one- and two-photon absorption resonances that lead to suitably low optical loss and appreciable dispersion enhancement of the real part of γ. We implemented this strategy in a soluble bis(selenopyrylium) heptamethine dye that exhibits a real part of γ that is exceptionally large throughout the wavelength range used for telecommunications, and an imaginary part of γ, a measure of nonlinear loss, that is smaller by two orders of magnitude. This combination is critical in enabling low-power, high-contrast optical switching.

Exciton–polariton spin switches

Abstract: An all-optical spin switch based on exciton–polaritons in a semiconductor microcavity is demonstrated. These results may lead to small and fast spin-based on-chip logic devices.

Three-dimensional structure and multistable optical switching of triple-twisted particle-like excitations in anisotropic fluids

Abstract: Control of structures in soft materials with long-range order forms the basis for applications such as displays, liquid-crystal biosensors, tunable lenses, distributed feedback lasers, muscle-like actuators and beam-steering devices. Bistable, tristable and multistable switching of well-defined structures of molecular alignment is of special interest for all of these applications. Here we describe the facile optical creation and multistable switching of localized configurations in the molecular orientation field of a chiral nematic anisotropic fluid. These localized chiro-elastic particle-like excitations--dubbed 'triple-twist torons'--are generated by vortex laser beams and embed the localized three-dimensional (3D) twist into a uniform background. Confocal polarizing microscopy and computer simulations reveal their equilibrium internal structures, manifesting both skyrmion-like and Hopf fibration features. Robust generation of torons at predetermined locations combined with both optical and electrical reversible switching can lead to new ways of multistable structuring of complex photonic architectures in soft materials.

DOS: a scalable optical switch for datacenters

Abstract: This paper discusses the architecture and performance studies of Datacenter Optical Switch (DOS) designed for scalable and high-throughput interconnections within a data center. DOS exploits wavelength routing characteristics of a switch fabric based on an Arrayed Waveguide Grating Router (AWGR) that allows contention resolution in the wavelength domain. Simulation results indicate that DOS exhibits lower latency and higher throughput even at high input loads compared with electronic switches or previously proposed optical switch architectures such as OSMOSIS [4, 5] and Data Vortex [6, 7]. Such characteristics, together with very high port count on a single switch fabric make DOS attractive for data center applications where the traffic patterns are known to be bursty with high temporary peaks [13]. DOS exploits the unique characteristics of the AWGR fabric to reduce the delay and complexity of arbitration. We present a detailed analysis of DOS using a cycle-accurate network simulator. The results show that the latency of DOS is almost independent of the number of input ports and does not saturate even at very high (approx 90%) input load. Furthermore, we show that even with 2 to 4 wavelengths, the performance of DOS is significantly better than an electrical switch network based on state-of-the-art flattened butterfly topology.

Ultrafast all-optical switching in a silicon-nanocrystal-based silicon slot waveguide at telecom wavelengths.

Abstract: We demonstrate experimentally all-optical switching on a silicon chip at telecom wavelengths. The switching device comprises a compact ring resonator formed by horizontal silicon slot waveguides filled with highly nonlinear silicon nanocrystals in silica. When pumping at power levels about 100 mW using 10 ps pulses, more than 50% modulation depth is observed at the switch output. The switch performs about 1 order of magnitude faster than previous approaches on silicon and is fully fabricated using complementary metal oxide semiconductor technologies.

An ultra-small, low-power all-optical flip-flop memory on a silicon chip

Abstract: A 7.5pm-diameter InP microdisk laser, integrated on an SOI waveguide is demonstrated as all-optical flip-flop working in continuous-wave regime with an electrical power consumption of several mW, and allowing switching in 60ps with pulses of 1.8fJ.

Photoconductively loaded plasmonic nanoantenna as building block for ultracompact optical switches.

Abstract: We propose and explore theoretically a new concept of ultrafast optical switches based on nonlinear plasmonic nanoantennas. The antenna nanoswitch operates on the transition from the capacitive to conductive coupling regimes between two closely spaced metal nanorods. By filling the antenna gap with amorphous silicon, progressive antenna-gap loading is achieved due to variations in the free-carrier density in the semiconductor. Strong modification of the antenna response is observed both in the far-field response and in the local near-field intensity. The large modulation depth, low switching threshold, and potentially ultrafast time response of antenna switches holds promise for applications ranging from integrated nanophotonic circuits to quantum information devices.

InP Photonic Integrated Circuits

Abstract: InP is an ideal integration platform for optical generation, switching, and detection components operating in the range of 1.3-1.6 m wavelength, which is preferred for data transmission in the most prevalent silica-based optical fiber. We review the current state of the art in advanced InP photonic ICs.

High-frequency switch module

Abstract: A high-frequency switch module which comprises a high-frequency switch circuit connected among an antenna, a transmission circuit, and a reception circuit and comprising switching elements and a surface acoustic wave filter connected between the high-frequency switch circuit and the reception circuit, uses a laminate constituted of dielectric layers having electrode patterns as the multilayered board, and has a phase correction circuit disposed between the switch circuit and the surface acoustic wave filter, wherein the high-frequency switch circuit comprises a switching element, a transmission line, and a capacitor as main elements, with at least a part of the transmission line and the capacitor constituted of an electrode pattern in the laminate, and with the surface acoustic wave filter mounted on the laminate.

Optically Pumped Frequency Reconfigurable Antenna Design

Abstract: This letter presents a novel frequency reconfigurable antenna design using photoconductive silicon elements as optical switches. By illuminating these silicon elements with light of suitable wavelength, their physical properties can be altered from that of a semiconductor to almost metal-like, which in turn alters the radiation properties of the antenna structure. Our work builds on similar work conducted in the past, but goes further by demonstrating a new geometry for coupling the light energy onto the silicon switches, thereby facilitating conformal integration of such reconfigurable antennas into next-generation wireless devices. In this letter, we first present a theoretical model characterizing the behavior of silicon substrate under light illumination. We then present experimental results on a stripline circuit employing a single silicon switch under light illumination and compare the theoretical model to experimental measurements. Finally, a novel frequency reconfigurable antenna design utilizing our new coupling geometry is designed, and its experimentally measured RF performance is compared to numerical simulations.

Low-crosstalk 2 × 2 thermo-optic switch with silicon wire waveguides

Abstract: We demonstrate a low-crosstalk 2 × 2 thermo-optic switch with silicon wire waveguides. The device is based on a 2 × 2 array of Mach–Zehnder interferometer (MZI) switches. Lowest crosstalk levels of –50 dB and –30 dB are obtained for ‘bar’ and ‘cross’ switching states, respectively. An intersection in the switch is important for low-crosstalk operation. The power consumption of one MZI element switch is 40 mW and the total power consumption of the device is at most 160 mW.

Synthesis of CdZnO thin film as a potential candidate for optical switches

Abstract: Cadmium doped zinc oxide thin films have been prepared using a thermal decomposition technique. The influence of Cd as a doping agent on the structure, optical and nonlinear optical properties was carefully investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a UV–vis spectrophotometer. A deep correlation has been found between the surface roughness and the optical properties. The roughness is found to deteriorate the nonlinear response, such that the highest nonlinear susceptibility χ (3) is obtained for the smoothest layer. The third-order nonlinear susceptibility χ (3) has been calculated using the Frumer model, and is estimated to be 3.37×10 −10 esu. The dispersion of the refractive index of the prepared thin film is shown to follow the single electronic oscillator model. From the model, the values of oscillator strength ( E d ), oscillator energy ( E o ) and dielectric constant ( e ∞ ) have been determined. The conductivity has been measured as a function of the energy of the photons, revealing marginal change at energies below 3.15 eV, while above this value there is a large increase in the conductivity. This suggests that CdZnO is a potential candidate for applications in optical devices such as optical limiter and optical switching.

Crosstalk noise and bit error rate analysis for optical network-on-chip

Abstract: Crosstalk noise is an intrinsic characteristic of photonic devices used by optical networks-on-chip (ONoCs) as well as a potential issue. For the first time, this paper analyzed and modeled the crosstalk noise, signal-to-noise ratio (SNR), and bit error rate (BER) of optical routers and ONoCs. The analytical models for crosstalk noise, minimum SNR, and maximum BER in mesh-based ONoCs are presented. An automated crosstalk analyzer for optical routers is developed. We find that crosstalk noise significantly limits the scalability of ONoCs. For example, due to crosstalk noise, the maximum BER is 10−3 on the 8×8 mesh-based ONoC using an optimized crossbar-based optical router. To achieve the BER of 10−9 for reliable transmissions, the maximum ONoC size is 6×6. A novel compact high-SNR optical router is proposed to improve the maximum ONoC size to 8×8.

Tunable one-way cross-waveguide splitter based on gyromagnetic photonic crystal

Abstract: We report our design of a tunable one-way cross-waveguide splitter, resulting from the broken time-reversal symmetry, based on the edge modes of gyromagnetic photonic crystal. Mode control is accomplished by altering the radius or refractive index of a single central electro-optical rod. The on-off switch of the channels can be manipulated by external electric or magnetic field. Coupled-mode theory between defect modes and waveguide modes was used to characterize the transmission efficiency of the channels.

Tb/s Optical Logic Gates Based on Quantum-Dot Semiconductor Optical Amplifiers

Abstract: The performance of an ultrafast all-optical logic gate based on quantum-dot semiconductor optical amplifier (QD-SOA) has been theoretically analyzed in this paper. We introduce a novel approach to accelerate the gain recovery process with a control pulse (CP) using the cross-gain modulation (XGM) effect. It is shown that the optical XOR gate in a Mach-Zehnder interferometer-based structure is feasible at Tb/s speeds with proper quality factor. The operation capability at 2.5 Tb/s with a Q-factor of 4.9 and 2 Tb/s with a Q -factor of 8.8 is reported for the first time. This capability indicates great potential for ultrafast all-optical signal processing and switching.

Tb/s Coherent Optical OFDM Systems Enabled by Optical Frequency Combs

Abstract: This paper discusses the realization of terabit per second high speed and high spectral-efficiency optical transmissions using much lower speed electronics and optoelectronics through parallel processing of coherent optical frequency combs at both the transmitter and receiver. The coherent and parallel processing enables electrical-to-optical and optical-to-electrical (E/O and O/E) conversion of wide-bandwidth optical signals which would otherwise exceeds the capability of conventional optoelectronics. In the first experiment, an optical frequency comb (OFC) generator provides 32 comb lines with less than 5-dB power variation. Subsequently, 1.008-Tb/s modulation capability is realized on 32 × 106 OFDM subcarriers with 16-QAM modulation in a 318-GHz seamless optical bandwidth. It demonstrates an effective way to generate an optical OFDM signal with tens of times wider optical bandwidth than that of analog-to-digital converters and digital-to-analog converters (ADC/DAC). The second experiment demonstrates simultaneous detection of multiple OFDM bands from a 32-band coherent optical OFDM signal using another optical frequency comb, a silica planar lightwave circuit (PLC) that implemented the major optical devices, and two pairs of balanced photodiodes. The experimental results indicate prospects for an optically integrated coherent optical OFDM system on a chip-scale platform.

Optical switching of a metamaterial by temperature controlling

Abstract: We have fabricated a metamaterial of metal/semiconductor/metal sandwich nanostrips structure comprising a pair of gold strips and a vanadium dioxide (VO2) strip. The optical response of the metamaterial has been studied. The results indicate the nanostructure with VO2 strips can be used as a temperature-controlling optical switch and the mechanism of this switch can be explained by the magnetic resonance.

Compact Optical Switches and Modulators Based on Dispersion Engineered Photonic Crystals

Abstract: We use slow-light photonic crystals to enhance optical switching and modulation in silicon. By using dispersion-engineered designs, a switch as short as 5 ?m was achieved, in which we have demonstrated rerouting of optical pulses on a 3-ps time scale through the absorption of a femtosecond pulse. We additionally demonstrate a modulator with a Mach-Zehnder interferometer (MZI) configuration with flat-band slow-light photonic crystal phase shifters that is designed to give a large group-index-bandwidth product. An extinction ratio in excess of 15 dB is obtained over the entire 11-nm bandwidth of the modulator.

Hybrid switch circuit

Abstract: A hybrid switch circuit includes a hybrid switch that couples an input conductor connected to an AC power supply to an output conductor connected to a load. The hybrid switch includes a power semiconductor in parallel with an electromagnetic relay. A control circuit turns on the hybrid switch by turning on the power semiconductor at a zero-voltage crossing of the AC voltage to provide a conductive path and then closing the relay to provide a conductive bypass path that bypasses the power semiconductor. The control circuit turns off the hybrid switch by opening the relay and subsequently turning off the power semiconductor at a zero crossing of the load current. The control circuit operates in response to at least one switch control signal that indicates whether an operating fault condition exists.

A frequency-addressed plasmonic switch based on dual-frequency liquid crystals

Abstract: A frequency-addressed plasmonic switch was demonstrated by embedding a uniform gold nanodisk array into dual-frequency liquid crystals (DFLCs). The optical properties of the hybrid system were characterized by extinction spectra of localized surface plasmon resonances (LSPRs). The LSPR peak was tuned using a frequency-dependent electric field. A ∼4 nm blueshift was observed for frequencies below 15 kHz, and a 23 nm redshift was observed for frequencies above 15 kHz. The switching time for the system was ∼40 ms. This DFLC-based active plasmonic system demonstrates an excellent, reversible, frequency-dependent switching behavior and could be used in future integrated nanophotonic circuits.

Analytical model for optical bistability in nonlinear metal nano-antennae involving Kerr materials.

Abstract: Optical bistability at nanoscale is a promising way to realize optical switching, a key component of integrated nanophotonic devices. In this work we present an analytical model for optical bistability in a metal nano-antenna involving Kerr nonlinear medium based on detailed analysis of the correlation between the incident and extinction light intensity under surface plasmon resonance (SPR). The model allows one to construct a clear picture on how the threshold, contrast, and other characteristics of optical bistability are influenced by the nonlinear coefficient, incident light intensity, local field enhancement factor, SPR peak width, and other physical parameters of the nano-antenna. It shows that the key towards low threshold power and high contrast optical bistability in the nanosystem is to reduce the SPR peak width. This can be achieved by reducing the absorption of metal materials or introducing gain media into nanosystems.

Hybrid optical/electrical switching system for data center networks

Abstract: In one aspect, a system includes one or more electrical switches to transfer data in a data network; one or more optical switching groups coupled to each electrical switch, each switching group having one or more server racks, each server rack coupled to a top of rack (TOR) switch and an optical transceiver coupled to the TOR switch; and an optical switching unit (OSU) coupled to the one or more optical switching groups.

A Hierarchical Hybrid Optical-Electronic Network-on-Chip

Abstract: Network-on-chip (NoC) can improve the performance, power efficiency, and scalability of multiprocessor system-on-chip (MPSoC) However, traditional NoCs using metallic interconnects consume significant amount of power to deliver even higher communication bandwidth required in the near future Optical NoCs are based on CMOS-compatible optical waveguides and micro resonators, and promise significant bandwidth and power advantages In this paper, we propose a hybrid optical mesh NoC, HOME, which utilizes optical waveguides as well as metallic interconnects in a hierarchical manner HOME employs a new set of protocols to improve the network throughput and latency We compared HOME with a matched optical mesh NoC for a 64-core MPSoC in 45nm, using SPICE simulations and our cycle-accurate multi-objective NoC simulation platform, MoLab Comparing with the optical mesh NoC, HOME uses 75% less optical/electronic interfaces and laser diodes Simulation results show that HOME achieves 17% higher throughput and 40% less latency while consuming 42% less power

Optical switch using a deformable liquid droplet

Abstract: An optical switch based on a deformable liquid droplet is demonstrated. The device consists of a clear liquid droplet surrounded by a black liquid. In the voltage-off state, the incident light is absorbed by the black liquid. As the voltage increases, the dielectric force reshapes the droplet by uplifting its dome. As the dome touches the top substrate, a clear channel is opened, allowing the incident light to pass through. Once the voltage is removed, the deformed droplet relaxes back to its original shape and the channel is closed. Devices based on such an operation mechanism have potential applications in light shutters, variable optical attenuators, adaptive irises, and displays.