WorldWideScience

Sample records for broadband

  1. Adoption of Broadband Services

    DEFF Research Database (Denmark)

    Falch, Morten

    2008-01-01

    Broadband is seen as a key infrastructure for developing the information society. For this reason many Governments are actively engaged in stimulating investments in broadband infrastructures and use of broadband services. This chapter compares a wide range of broadband strategies in the most...... successful markets for broadband. This is done through analysis of national policies in three European countries-Denmark, Sweden, and Germany-and the U.S., Japan, and South Korea. We concluded that successful implementation of broadband depends on the kind of policy measures to be taken at the national level...

  2. Broadband Telecommunications Benchmarking Study

    OpenAIRE

    2004-01-01

    This report assesses Ireland's competitiveness relative to 21 countries, with particular focus on the broadband telecommunications requirements of the enterprise sector. The report outlines strengths and weaknesses that currently exist and progress that has already been made. It also makes a series of recommendations to further promote the development of the broadband market in Ireland.

  3. The Broadband Buzz.

    Science.gov (United States)

    Buchanan, Bruce

    2003-01-01

    "Broadband," the term for a variety of high-speed Internet options, opens up many opportunities for online classroom learning. Challenges for school districts include keeping the network running, training teachers, and paying for it. A sidebar lists broadband resources. (MLF)

  4. Broadband adoption by SMES

    OpenAIRE

    Oni, Oluwasola

    2007-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Because the benefits of broadband for businesses have been widely publicized, the UK government has tried to ensure that there is a wide and fast take-up of the technology. Initial figures showed that broadband adoption by SMEs was particularly slow and there has been little research on the use of broadband by businesses, particularly SMEs. An in-depth study into the roles and activities of t...

  5. Direct UV-written broadband directional broadband planar waveguide couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....

  6. Czech way to broadband

    Czech Academy of Sciences Publication Activity Database

    Kuchar, Anton; Peterka, J.; Hrstka, J.; Hankiewiczová, H.

    -, August (2006), s. 274-278. ISSN 1106-2975. [FITCE Congress /45./. Athens, 30.08.2006-02.09.2006] Grant ostatní: BReATH Consortium EU(XE) EC FP6 1ST Programme Institutional research plan: CEZ:AV0Z20670512 Keywords : telecommunication networks * Internet * broadband networks Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  7. Metasurface Broadband Solar Absorber

    OpenAIRE

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Milan Sykora; Nina R. Weisse-Bernstein; Luk, Ting S.; Antoinette J. Taylor; Dalvit, Diego A. R.; Hou-Tong Chen

    2016-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experiment...

  8. Broadband terahertz spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Wenhui Fan

    2011-01-01

    1.Introduction Spanning the frequency range between the infrared (IR) radiation and microwaves,terahertz (THz) waves are,also known as T-rays,T-lux,or simply called THz,assigned to cover the electromagnetic spectrum typically from 100 GHz (1011 Hz) to 10 THz (1013 Hz),namely,from 3 mm to 30 μm in wavelength,although slightly different definitions have been quoted by different authors.For a very long time,THz region is an almost unexplored field due to its rather unique location in the electromagnetic spectrum.Well-known techniques in optical or microwave region can not be directly employed in the THz range because optical wavelengths are too short and microwave wavelengths are too long compared to THz wavelengths.%An overview of the major techniques to generate and detect THz radiation so far, especially the major approaches to generate and detect coherent ultra-short THz pulses using ultra-short pulsed laser, has been presented. And also, this paper, in particularly, focuses on broadband THz spectroscopy and addresses on a number of issues relevant to generation and detection of broadband pulsed THz radiation as well as broadband time-domain THz spectroscopy (THz-TDS) with the help of ultra-short pulsed laser. The time-domain waveforms of coherent ultra-short THz pulses from photoconductive antenna excited by femtosecond laser with different pulse durations and their corresponding Fourier-transformed spectra have been obtained via the numerical simulation of ultrafast dynamics between femtosecond laser pulse and photoconductive material. The origins of fringes modulated on the top of broadband amplitude spectrum, which is measured by electric-optic detector based on thin nonlinear crystal and extracted by fast Fourier transformation, have been analyzed and the major solutions to get rid of these fringes are discussed.

  9. Broadband Radio Service (BRS) and Educational Broadband Service (EBS) Transmitters

    Data.gov (United States)

    Department of Homeland Security — The Broadband Radio Service (BRS), formerly known as the Multipoint Distribution Service (MDS)/Multichannel Multipoint Distribution Service (MMDS), is a commercial...

  10. Broadband frequency conversion

    DEFF Research Database (Denmark)

    Sanders, Nicolai; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter;

    We present a simple, passive and static setup for broadband frequency conversion. By using simple optical components like lenses, mirrors and gratings, we obtain the spectral angular dispersion to match the second harmonic generation phasematching angles in a nonlinear BiBO crystal. We are able to...... frequency double a single-frequency diode laser, tunable in the 1020-1090 nm range, with almost equal efficiency for all wavelengths. In the experimental setup, the width of the phasematch was increased with a factor of 50. The method can easily be extended to other wavelength ranges and nonlinear crystals...

  11. Broadband pendulum energy harvester

    Science.gov (United States)

    Liang, Changwei; Wu, You; Zuo, Lei

    2016-09-01

    A novel electromagnetic pendulum energy harvester with mechanical motion rectifier (MMR) is proposed and investigated in this paper. MMR is a mechanism which rectifies the bidirectional swing motion of the pendulum into unidirectional rotation of the generator by using two one-way clutches in the gear system. In this paper, two prototypes of pendulum energy harvester with MMR and without MMR are designed and fabricated. The dynamic model of the proposed MMR pendulum energy harvester is established by considering the engagement and disengagement of the one way clutches. The simulation results show that the proposed MMR pendulum energy harvester has a larger output power at high frequencies comparing with non-MMR pendulum energy harvester which benefits from the disengagement of one-way clutch during pendulum vibration. Moreover, the proposed MMR pendulum energy harvester is broadband compare with non-MMR pendulum energy harvester, especially when the equivalent inertia is large. An experiment is also conducted to compare the energy harvesting performance of these two prototypes. A flywheel is attached at the end of the generator to make the disengagement more significant. The experiment results also verify that MMR pendulum energy harvester is broadband and has a larger output power at high frequency over the non-MMR pendulum energy harvester.

  12. Broadband terahertz fiber directional coupler

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Jepsen, Peter Uhd; Bang, Ole

    2010-01-01

    We present the design of a short broadband fiber directional coupler for terahertz (THz) radiation and demonstrate a 3 dB coupler with a bandwidth of 0:6 THz centered at 1:4 THz. The broadband coupling is achieved by mechanically downdoping the cores of a dual-core photonic crystal fiber by...

  13. Metasurface Broadband Solar Absorber

    CERN Document Server

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  14. Metasurface Broadband Solar Absorber

    Science.gov (United States)

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  15. Metamaterial broadband angular selectivity

    Science.gov (United States)

    Shen, Yichen; Ye, Dexin; Wang, Li; Celanovic, Ivan; Ran, Lixin; Joannopoulos, John D.; Soljačić, Marin

    2014-09-01

    We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each effective anisotropic layer is constructed from a multilayered metamaterial. We show that by simply changing the structure of the metamaterials, the selective angle can be tuned to a broad range of angles; and, by increasing the number of stacks, the angular transmission window can be made as narrow as desired. As a proof of principle, we realize the idea experimentally in the microwave regime. The angular selectivity and tunability we report here can have various applications such as in directional control of electromagnetic emitters and detectors.

  16. Metamaterial Broadband Angular Selectivity

    CERN Document Server

    Shen, Yichen; Wang, Zhiyu; Wang, Li; Celanovic, Ivan; Ran, Lixin; Joannopoulos, John D; Soljacic, Marin

    2014-01-01

    We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each effective anisotropic layer is constructed from a multilayered metamaterial. We show that by simply changing the structure of the metamaterials, the selective angle can be tuned to a broad range of angles; and, by increasing the number of stacks, the angular transmission window can be made as narrow as desired. As a proof of principle, we realize the idea experimentally in the microwave regime. The angular selectivity and tunability we report here can have various applications such as in directional control of electromagnetic emitters and detectors.

  17. Broadband and ultra-broadband modular half-wave plates

    Science.gov (United States)

    Dimova, Emiliya; Huang, Wei; Popkirov, George; Rangelov, Andon; Kyoseva, Elica

    2016-05-01

    We experimentally demonstrate broadband and ultra-broadband spectral bandwidth modular half-wave plates. Both modular devices comprise an array of rotated single half-wave plates (HWPs), whereby for broadband and ultra-broadband performance we use standard and commercial achromatic HWPs, respectively. The bandwidth of the modular HWPs depends on the number N of individual HWPs used and in this paper we experimentally investigate this for N = { 3 , 5 , 7 , 9 }. The elements in the arrays are rotated at specific angles with respect to their fast-polarization axes, independent of the nature of the birefringent material. We find the rotation angles using an analogy to the technique of composite pulses, which is widely used for control in nuclear magnetic resonance.

  18. Broadband Advanced Spectral System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NovaSol proposes to develop an advanced hyperspectral imaging system for earth science missions named BRASS (Broadband Advanced Spectral System). BRASS combines...

  19. Heterogeneous broadband network

    Science.gov (United States)

    Dittmann, Lars

    1995-11-01

    Although the vision for the future Integrated Broadband Communication Network (IBCN) is an all optical network, it is certain that for a long period to come, the network will remain very heterogeneous, with a mixture of different physical media (fiber, coax and twisted pair), transmission systems (PDH, SDH, ADSL) and transport protocols (TCP/IP, AAL/ATM, frame relay). In the current work towards the IBCN, the ATM concept is considered the generic network protocol for both public and private network, with the ability to use different underlying transmission protocols and, through adaptation protocols, provide the appropriate services (old as well as new) to the customer. One of the major difficulties of heterogeneous network is the restriction that is usually given by the lowest common denominator, e.g. in terms of single channel capacity. A possible way to overcome these limitations is by extending the ATM concept with a multilink capability, that allows us to use separate resources as one common. The improved flexibility obtained by this protocol extension further allows a real time optimization of network and call configuration, without any impact on the quality of service seen from the user. This paper describes an example of an ATM based multilink protocol that has been experimentally implemented within the RACE project 'STRATOSPHERIC'. The paper outlines the complexity of introducing an extra network functionality compared with the added value, such as an improved ability to recover an error due to a malfunctioning network component.

  20. Broadband transmission EPR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Wilfred R Hagen

    Full Text Available EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (biomolecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed.

  1. Broadband accelerator control network

    International Nuclear Information System (INIS)

    A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AG) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating system has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel

  2. Broadband Rotational Spectroscopy

    Science.gov (United States)

    Pate, Brooks

    2014-06-01

    The past decade has seen several major technology advances in electronics operating at microwave frequencies making it possible to develop a new generation of spectrometers for molecular rotational spectroscopy. High-speed digital electronics, both arbitrary waveform generators and digitizers, continue on a Moore's Law-like development cycle that started around 1993 with device bandwidth doubling about every 36 months. These enabling technologies were the key to designing chirped-pulse Fourier transform microwave (CP-FTMW) spectrometers which offer significant sensitivity enhancements for broadband spectrum acquisition in molecular rotational spectroscopy. A special feature of the chirped-pulse spectrometer design is that it is easily implemented at low frequency (below 8 GHz) where Balle-Flygare type spectrometers with Fabry-Perot cavity designs become technologically challenging due to the mirror size requirements. The capabilities of CP-FTMW spectrometers for studies of molecular structure will be illustrated by the collaborative research effort we have been a part of to determine the structures of water clusters - a project which has identified clusters up to the pentadecamer. A second technology trend that impacts molecular rotational spectroscopy is the development of high power, solid state sources in the mm-wave/THz regions. Results from the field of mm-wave chirped-pulse Fourier transform spectroscopy will be described with an emphasis on new problems in chemical dynamics and analytical chemistry that these methods can tackle. The third (and potentially most important) technological trend is the reduction of microwave components to chip level using monolithic microwave integrated circuits (MMIC) - a technology driven by an enormous mass market in communications. Some recent advances in rotational spectrometer designs that incorporate low-cost components will be highlighted. The challenge to the high-resolution spectroscopy community - as posed by Frank De

  3. Driving demand for broadband networks and services

    CERN Document Server

    Katz, Raul L

    2014-01-01

    This book examines the reasons why various groups around the world choose not to adopt broadband services and evaluates strategies to stimulate the demand that will lead to increased broadband use. It introduces readers to the benefits of higher adoption rates while examining the progress that developed and emerging countries have made in stimulating broadband demand. By relying on concepts such as a supply and demand gap, broadband price elasticity, and demand promotion, this book explains differences between the fixed and mobile broadband demand gap, introducing the notions of substitution and complementarity between both platforms. Building on these concepts, ‘Driving Demand for Broadband Networks and Services’ offers a set of best practices and recommendations aimed at promoting broadband demand.  The broadband demand gap is defined as individuals and households that could buy a broadband subscription because they live in areas served by telecommunications carriers but do not do so because of either ...

  4. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  5. Broadband perfect polarization conversion metasurfaces

    International Nuclear Information System (INIS)

    We propose a broadband perfect polarization conversion metasurface composed of copper sheet-backed asymmetric double spilt ring resonator (DSRR). The broadband perfect polarization convertibility results from metallic ground and multiple plasmon resonances of the DSRR. Physics of plasmon resonances are governed by the electric and magnetic resonances. Both the simulation and measured results show that the polarization conversion ratio (PCR) is higher than 99% for both x- and y-polarized normally incident EM waves and the fractional bandwidth is about 34.5%. The metasurface possesses the merits of high PCR and broad bandwidth, and thus has great application values in novel polarization-control devices. (paper)

  6. The Skill Complementarity of Broadband Internet

    OpenAIRE

    Akerman, Anders; Gaarder, Ingvil; Mogstad, Magne

    2013-01-01

    Does adoption of broadband internet in firms enhance labor productivity and increase wages? And is this technological change skill biased or factor neutral? We exploit rich Norwegian data with firm-level information on value added, factor inputs and broadband adoption to answer these questions. We estimate production functions where firms can change their technology by adopting broadband internet. A public program with limited funding rolled out broadband access points, and provides plausibly...

  7. Broadband Internet's Value for Rural America

    OpenAIRE

    Stenberg, Peter L.; Morehart, Mitchell J.; Vogel, Stephen J.; Cromartie, John; Breneman, Vincent E.; Brown, Dennis M.

    2009-01-01

    As broadband—or high-speed—Internet use has spread, Internet applications requiring high transmission speeds have become an integral part of the “Information Economy,” raising concerns about those who lack broadband access. This report analyzes (1) rural broadband use by consumers, the community-at-large, and businesses; (2) rural broadband availability; and (3) broadband’s social and economic effects on rural areas. It also summarizes results from an ERS-sponsored workshop on rural broadband...

  8. Achieving universal access to broadband

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders

    2009-01-01

    The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures to be...

  9. Broadband SHF Direction-Finder

    Directory of Open Access Journals (Sweden)

    S. Radionov

    2008-06-01

    Full Text Available The original design of the compact broadband direction-finder is presented in this paper. The cylindrical monopole antenna serves as a primary source of the reflector- type antenna. "Zero-amplitude" technique is used for bearing the SHF sources. The model experiments with the proposed direction-finder prototype in the frequency band 6 GHz - 11 GHz have been carried out.

  10. Broadband Loaded Cylindrical Monopole Antenna

    OpenAIRE

    Boucher, Solene; Sharaiha, Ala; Potier, Patrick

    2013-01-01

    Ahstract-A broadband printed monopole antenna based on the variation of the conductivity along its length is proposed .. The result indicates that a non-monotonous repartition provides interesting performances in terms of impedance bandwidth but also concerning antenna gain. The achievement of the method is demonstrated through its application, using the carbon fibers to perform this conductivity variation. Monopole antenna presents a large impedance bandwidth of 123% with an interesting gain...

  11. Analysis of the Proposed Ghana Broadband Strategy

    DEFF Research Database (Denmark)

    Williams, Idongesit; Botwe, Yvonne

    This project studied the Ghana Broadband Strategy with the aim of evaluating the recommendations in the strategy side by side the broadband development in Ghana. The researchers conducted interviews both officially and unofficially with ICT stakeholders, made observations, studied Government...... intervention policies recommended in the Ghana broadband policy is used to evaluate the broadband market to find out whether the strategy consolidates with the Strengths and opportunities of the market and whether it corrects the anomalies that necessitate the weaknesses and threats to the market....... The strategy did address some threats and weaknesses of the broadband market. It also consolidated on some strengths and opportunities of the broadband market. The researchers also discovered that a market can actually grow without a policy. But a market will grow faster if a well implemented policy is guiding...

  12. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  13. The economic impact of broadband deployment in Kentucky

    OpenAIRE

    David Shideler; Narine Badasyan; Laura Taylor

    2007-01-01

    Significant resources are being invested by government and the private sector in broadband infrastructure to increase broadband deployment and use. With a unique dataset of broadband availability (sorted by county), the authors assess whether broadband infrastructure has affected the industrial competitiveness of Kentucky counties. Their results suggest that broadband availability increases employment growth in some industries but not others.

  14. Broadband b: scaling law of P-wave broadband radiated energy

    OpenAIRE

    Wu, Zhongliang; Kim, So G.; Gao, Yuan

    1995-01-01

    We analyzed the NEIC broadband radiated energy catalogue and found that the scaling law of earthquake energy deduced from Gutenegberg-Richter’s law is not valid in a quantitative sense. The analysis of broadband radiated energy, however, also shows a scaling law, which may be represented by a broadband b value.

  15. Understanding broadband over power line

    CERN Document Server

    Held, Gilbert

    2006-01-01

    Understanding Broadband over Power Line explores all aspects of the emerging technology that enables electric utilities to provide support for high-speed data communications via their power infrastructure. This book examines the two methods used to connect consumers and businesses to the Internet through the utility infrastructure: the existing electrical wiring of a home or office; and a wireless local area network (WLAN) access point.Written in a practical style that can be understood by network engineers and non-technologists alike, this volume offers tutorials on electric utility infrastru

  16. Broadband tuning of optomechanical cavities

    Science.gov (United States)

    Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Lee, Sunwoo; Lipson, Michal

    2011-01-01

    We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 $\\mu$W/nm. By choosing a relatively low optical Q resonance ($\\approx$18,000) we prevent the cavity from reaching the regime of regenerative optomechanical oscillations. The static mechanical displacement induced by optical gradient forces is estimated to be as large as 60 nm.

  17. Broadband Tuning of Optomechanical Cavities

    OpenAIRE

    Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Lee, Sunwoo; Lipson, Michal

    2010-01-01

    We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 $\\mu$W/nm. By choosing a relatively low optical Q resonance ($\\approx$18,000) we prevent the cavity from ...

  18. Broadband Tuning of Optomechanical Cavities

    CERN Document Server

    Wiederhecker, Gustavo S; Lee, Sunwoo; Lipson, Michal

    2010-01-01

    We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 $\\mu$W/nm. By choosing a relatively low optical Q resonance ($\\approx$18,000) we prevent the cavity from reaching the regime of regenerative optomechanical oscillations. The static mechanical displacement induced by optical gradient forces is estimated to be as large as 60 nm.

  19. Achieving Universal Access to Broadband

    Directory of Open Access Journals (Sweden)

    Morten FALCH

    2009-01-01

    Full Text Available The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures to be applied. The paper concludes that other policy measure than the classical universal service obligation are in play, and discusses various policy measures taking the Lisbon process as a point of departure. Available policy measures listed in the paper include, universal service obligation, harmonization, demand stimulation, public support for extending the infrastructure, public private partnerships (PPP, and others.

  20. Broadband Wireline Provider Service Summary; BBRI_wirelineSum12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of broadband Internet access in Rhode Island via all wireline technologies assessed by Broadband Rhode Island. Broadband...

  1. 78 FR 32165 - Broadband Over Power Lines

    Science.gov (United States)

    2013-05-29

    ... has potential applications for broadband and Smart Grid uses--while protecting incumbent radio... providing for Access BPL technology--which has potential applications for broadband and Smart Grid uses... study on In-House BPL in our consideration of Access BPL interference potential. However, that...

  2. 76 FR 71892 - Broadband Over Power Lines

    Science.gov (United States)

    2011-11-21

    ... BPL technology that has potential applications for broadband and Smart Grid while protecting incumbent... providing for Access BPL technology that has potential applications for broadband and Smart Grid while... used by manufacturers of HomePlug In-House BPL equipment, it is more stringent than is necessary...

  3. Broadband antenna arrays using planar horns

    OpenAIRE

    Braude, V. B.; Sukhovetskaya, S. B.

    1997-01-01

    Broadband antennas are vitally important for various applications ranging from TV broadcasting to carrier-free ground-probing radars. We propose a microwave broadband antenna array (BAA), which may be realised using microstrip planar horns — flared end-fire radiating slot lines, known as Vivaldi-type antennas.

  4. Customer Churn Prediction for Broadband Internet Services

    Science.gov (United States)

    Huang, B. Q.; Kechadi, M.-T.; Buckley, B.

    Although churn prediction has been an area of research in the voice branch of telecommunications services, more focused studies on the huge growth area of Broadband Internet services are limited. Therefore, this paper presents a new set of features for broadband Internet customer churn prediction, based on Henley segments, the broadband usage, dial types, the spend of dial-up, line-information, bill and payment information, account information. Then the four prediction techniques (Logistic Regressions, Decision Trees, Multilayer Perceptron Neural Networks and Support Vector Machines) are applied in customer churn, based on the new features. Finally, the evaluation of new features and a comparative analysis of the predictors are made for broadband customer churn prediction. The experimental results show that the new features with these four modelling techniques are efficient for customer churn prediction in the broadband service field.

  5. Broadband cloaking for flexural waves

    CERN Document Server

    Zareei, Ahmad

    2016-01-01

    The governing equation for elastic waves in flexural plates is not form invariant, and hence designing a cloak for such waves faces a major challenge. Here, we present the design of a perfect broadband cloak for flexural waves through the use of a nonlinear transformation, and by matching term-by-term the original and transformed equations. For a readily achievable flexural cloak in a physical setting, we further present an approximate adoption of our perfect cloak under more restrictive physical constraints. Through direct simulation of the governing equations, we show that this cloak, as well, maintains a consistently high cloaking efficiency over a broad range of frequencies. The methodology developed here may be used for steering waves and designing cloaks in other physical systems with non form-invariant governing equations.

  6. Interpreting Flux from Broadband Photometry

    CERN Document Server

    Brown, Peter J; Roming, Peter W A; Siegel, Michael

    2016-01-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broad-band photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by comparing in the natural units of the observations. We recommend that integrated flux measurements be made using a spectrum or spectral energy distribution whic...

  7. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    Airlines have been continuously upgrading their wide-body, long-haul aircraft with IFE (in-flight entertainment) systems that can support from 12 to 24 channels of video entertainment as well as provide the infrastructure to enable in-seat delivery of email and internet services. This is a direct consequence of increased passenger demands for improved in-flight services along with the expectations that broadband delivery systems capable of providing live entertainment (news, sports, financial information, etc.) and high speed data delivery will soon be available. The recent events of Sept. 11 have slowed the airline's upgrade of their IFE systems, but have also highlighted the compelling need for broadband aeronautical delivery systems to include operational and safety information. Despite the impact of these events, it is estimated that by 2005 more than 3000 long haul aircraft (servicing approximately 1 billion passengers annually) will be fully equipped with modern IFE systems. Current aircraft data delivery systems, which use either Inmarsat or NATS, are lacking in bandwidth and consequently are unsuitable to satisfy passenger demands for broadband email/internet services or the airlines' burgeoning data requirements. Present live video delivery services are limited to regional coverage and are not readily expandable to global or multiregional service. Faced with a compelling market demand for high data transport to aircraft, AirTV has been developing a broadband delivery system that will meet both passengers' and airlines' needs. AirTV is a global content delivery system designed to provide a range of video programming and data services to commercial airlines. When AirTV is operational in 2004, it will provide a broadband connection directly to the aircraft, delivering live video entertainment, internet/email service and essential operational and safety data. The system has been designed to provide seamless global service to all airline routes except for those

  8. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    Airlines have been continuously upgrading their wide-body, long-haul aircraft with IFE (in-flight entertainment) systems that can support from 12 to 24 channels of video entertainment as well as provide the infrastructure to enable in-seat delivery of email and internet services. This is a direct consequence of increased passenger demands for improved in-flight services along with the expectations that broadband delivery systems capable of providing live entertainment (news, sports, financial information, etc.) and high speed data delivery will soon be available. The recent events of Sept. 11 have slowed the airline's upgrade of their IFE systems, but have also highlighted the compelling need for broadband aeronautical delivery systems to include operational and safety information. Despite the impact of these events, it is estimated that by 2005 more than 3000 long haul aircraft (servicing approximately 1 billion passengers annually) will be fully equipped with modern IFE systems. Current aircraft data delivery systems, which use either Inmarsat or NATS, are lacking in bandwidth and consequently are unsuitable to satisfy passenger demands for broadband email/internet services or the airlines' burgeoning data requirements. Present live video delivery services are limited to regional coverage and are not readily expandable to global or multiregional service. Faced with a compelling market demand for high data transport to aircraft, AirTV has been developing a broadband delivery system that will meet both passengers' and airlines' needs. AirTV is a global content delivery system designed to provide a range of video programming and data services to commercial airlines. When AirTV is operational in 2004, it will provide a broadband connection directly to the aircraft, delivering live video entertainment, internet/email service and essential operational and safety data. The system has been designed to provide seamless global service to all airline routes except for those

  9. The impact of broadband in schools: Summary report

    OpenAIRE

    Underwood, Jean; Ault, Alison; Banyard, Phil; Bird, Karen; Dillon, Gayle; Hayes, Mary; Selwood, Ian; Somekh, Bridget; Twining, Peter

    2005-01-01

    Summary of the report, which reviews evidence for the impact of broadband in English schools, exploring; variations in provision in level of broadband connectivity. Links between the level of broadband activity and nationally accessible performance data; aspects of broadband connectivity and the school environment that contribute to better outcomes for pupils and teachers; academic and motivational benefits associated with educational uses of this technology.

  10. 47 CFR 27.1305 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Shared wireless broadband network. 27.1305... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network....

  11. 47 CFR 90.1405 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Shared wireless broadband network. 90.1405... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network....

  12. Broadband Adoption And Use In America

    Data.gov (United States)

    Federal Communications Commission — On February 23, 2010, the FCC published the results of its first Broadband Consumer Survey. This national survey of 5,005 adult Americans focused on non-adopters...

  13. 75 FR 6627 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-02-10

    ..., Washington, DC 20230; Help Desk e-mail: BroadbandUSA@usda.gov , Help Desk telephone: 1-877-508- 8364.../ . SUPPLEMENTARY INFORMATION: On January 22, 2010, NTIA published a Notice of Funds Availability (NOFA) (75 FR...

  14. Broadband V-band angular transition

    OpenAIRE

    Shcherbyna, Olga A.; Yashchyshyn, Yevhen

    2016-01-01

    A model of broadband V-band transition from a rectangular air-filled waveguide to substrate integrated waveguide has been proposed. Theoretical principles used for constructing the model of transition are also presented.

  15. Nanophotonic Design for Broadband Light Management

    Energy Technology Data Exchange (ETDEWEB)

    Kosten, Emily; Callahan, Dennis; Horowitz, Kelsey; Pala, Ragip; Atwater, Harry

    2014-10-13

    We describe nanophotonic design approaches for broadband light management including i) crossed-trapezoidal Si structures ii) Si photonic crystal superlattices, and iii) tapered and inhomogeneous diameter III-V/Si nanowire arrays.

  16. Wireless Broadband Access and Accounting Schemes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, we propose two wireless broadband access and accounting schemes. In both schemes, the accounting system adopts RADIUS protocol, but the access system adopts SSH and SSL protocols respectively.

  17. Household Demand for Broadband Internet Service

    OpenAIRE

    Gregory Rosston; Scott Savage; Donald Waldman

    2010-01-01

    As part of the Federal Communications Commission (“FCC”) National Broadband Report to Congress, we have been asked to conduct a survey to help determine consumer valuations of different aspects of broadband Internet service. Our empirical results show that reliability and speed are important characteristics of Internet service. The representative household is willing to pay about $20 per month for more reliable service and $45-48 for an increase in speed. Willingness-to-pay for speed increase...

  18. Rural Broadband At A Glance, 2009 Edition

    OpenAIRE

    Stenberg, Peter L.; Low, Sarah A

    2009-01-01

    Three-quarters of U.S. residents used the Internet to access information, education, and services in 2007. Broadband Internet access is becoming essential for both businesses and households; many compare its evolution to other technologies now considered common necessities—such as cars, electricity, televisions, microwave ovens, and cell phones. Although rural residents enjoy widespread access to the Internet, they are less likely to have high-speed, or broadband, Internet access than their u...

  19. Is European Broadband Ready for Smart Grid?

    DEFF Research Database (Denmark)

    Balachandran, Kartheepan; Pedersen, Jens Myrup

    2014-01-01

    In this short paper we compare the communication requirements for three Smart Grid scenarios with the availability of broadband and mobile communication networks in Europe. We show that only in the most demanding case - where data is collected and transmitted every second - a standard GSM....../GPRS connection is not enough. Whereas in the less demanding scenarios it is almost all of the European households that can be covered by a standard broadband technology for use with Smart Grid....

  20. Evaluation of arctic broadband surface radiation measurements

    OpenAIRE

    Matsui, N.; C. N. Long; J. Augustine; Halliwell, D.; T. Uttal; Longenecker, D.; O. Nievergall; Wendell, J.; Albee, R.

    2011-01-01

    The Arctic is a challenging environment for making in-situ radiation measurements. A standard suite of radiation sensors is typically designed to measure the total, direct and diffuse components of incoming and outgoing broadband shortwave (SW) and broadband thermal infrared, or longwave (LW) radiation. Enhancements can include various sensors for measuring irradiance in various narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are...

  1. Broadband circularly polarized antennas for UHF SATCOM

    OpenAIRE

    Tekin, İbrahim; Tekin, Ibrahim; Manzhura, Oksana; Niver, Edip

    2011-01-01

    Novel circularly polarized (CP) antenna configurations derived from Moxon type antenna (bent dipole element over a ground plane) for broadband VHF SATCOM applications. A sequence of topologies starting from a single vertical element to two vertical elements of the Moxon arms, then widened strip arm elements were studied. Further, arms were widened to bow tie structures with bents at 900.for achieving broadband operation. Bow tie elements were further split and optimized at a certain angle to...

  2. Broadband direct RF digitization receivers

    CERN Document Server

    Jamin, Olivier

    2014-01-01

    This book discusses the trade-offs involved in designing direct RF digitization receivers for the radio frequency and digital signal processing domains.  A system-level framework is developed, quantifying the relevant impairments of the signal processing chain, through a comprehensive system-level analysis.  Special focus is given to noise analysis (thermal noise, quantization noise, saturation noise, signal-dependent noise), broadband non-linear distortion analysis, including the impact of the sampling strategy (low-pass, band-pass), analysis of time-interleaved ADC channel mismatches, sampling clock purity and digital channel selection. The system-level framework described is applied to the design of a cable multi-channel RF direct digitization receiver. An optimum RF signal conditioning, and some algorithms (automatic gain control loop, RF front-end amplitude equalization control loop) are used to relax the requirements of a 2.7GHz 11-bit ADC. A two-chip implementation is presented, using BiCMOS and 65nm...

  3. Ultra-broadband photonic internet

    Science.gov (United States)

    Romaniuk, Ryszard S.

    2011-06-01

    In this paper, there is presented a review of our today's understanding of the ultimately broadband photonic Internet. A simple calculation is presented showing the estimate of the throughput of the core photonic network branches. Optoelectronic components, circuits, systems and signals, together with analogous electronic entities and common software layers, are building blocks of the contemporary Internet. Participation of photonics in development of the physical layer in the future Internet will probably increase. The photonics leads now to a better usage of the available bandwidth (increase of the spectral efficiency measured in Bit/s/Hz), increase in the transmission rate (from Gbps, via Tbps up to probably Pbps), increase in the transmission distance without signal regeneration (in distortion compensated active optical cables), increase in energy/power efficiency measured in W/Gbps, etc. Photonics may lead, in the future, to fully transparent optical networks and, thus, to essential increase in bandwidth and network reliability. It is expected that photonics (with biochemistry, electronics and mechatronics) may build psychological and physiological interface for humans to the future global network. The following optical signal multiplexing methods were considered, which are possible without O/E/O conversion: TDM-OTDM, FDM-CO-OFDM, OCDM-OCDMA, WDM-DWDM.

  4. Broadband antireflection coatings for multifunctional avionic displays

    Science.gov (United States)

    Kumari, Neelam; Kumar, Mukesh; Rao, P. K.; Karar, Vinod; Sharma, Amit Lochan

    2015-06-01

    Broadband Multilayer Antireflection (AR) coatings markedly improve the transmission efficiency of any optical component such as lens, prism, beam-splitter, beam combiner or a window. By reducing surface reflections over a wide wavelength range, broadband antireflection coatings improve transmission and enhance contrast which is desired in avionic displays. The broadband antireflection coating consisting of MgF2, ZrO2 and Al2O3 were designed to cover the whole visible spectrum and fabricated on optical grade glass substrate. The optical characterization of these coatings indicates reduction of the reflection to 2.28% as compared to 8.5 % at 545 nm (i.e. design wavelength of most avionic displays) for bare substrate making them useful in optical displays for avionic applications.

  5. Broadband absorption engineering of hyperbolic metafilm patterns

    Science.gov (United States)

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-03-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting.

  6. Participation in the broadband society in Denmark

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders; Skouby, Knud Erik

    2009-01-01

    The purpose of the paper is to provide an empirical overview of broadband developments in Denmark. The overview includes sections on coverage and penetration, connection speeds, retail prices, competition, interconnection prices, and residential access to Internet. The documentation shows...... passed the threshold set by the EU with respect to the relevance of initiating a discussion on the implementation of a universal service obligation on broadband. As documented in the paper, there are groups among primarily the elderly and the unemployed who do not have Internet access. Their own...... that Denmark is doing well in most international comparisons, but retail prices are still relatively high and connection speeds are lower than the best performing countries. In terms of households, approximately three quarters have broadband access. Denmark - and a number of other countries as well - has thus...

  7. Broadband Multilayered Array Antenna with EBG Reflector

    Directory of Open Access Journals (Sweden)

    P. Chen

    2013-01-01

    Full Text Available Most broadband microstrip antennae are implemented in the form of slot structure or laminate structure. The impedance bandwidth is broadened, but meanwhile, the sidelobe of the directivity pattern and backlobe level are enlarged. A broadband stacked slot coupling microstrip antenna array with EBG structure reflector is proposed. Test results indicate that the proposed reflector structure can effectively improve the directivity pattern of stacked antenna and aperture coupled antenna, promote the front-to-back ratio, and reduce the thickness of the antenna. Therefore, it is more suitable to be applied as an airborne antenna.

  8. Socio Technical Impact of Broadband Services in Baluchistan

    OpenAIRE

    Saira Ahthasham; Aftab Ahmed Shaikh; Muhammad Iqbal; Ahtsham Sajid; Amir Shahzad

    2012-01-01

    Broadband infrastructure is a key component of knowledge economy. Broadband service both on fixed and mobile networks are becoming an indicator of the knowledge economy. Globally it is viewed    that countries with developed broadband infrastructures are working more efficiently and effectively towards social and economic growth. To achieve worldwide broadband connectivity level Government of Pakistan and industry must play a combine role for the betterment and improvement of the said industr...

  9. 75 FR 29516 - Broadband Researchers' Data Workshop

    Science.gov (United States)

    2010-05-26

    ... a public meeting concerning the nature of data related to broadband Internet access and use that the..., ``Innovation in the Economy: Drive Economic Growth and Solve National Problems by Deploying a 21st Century...) to provide up-to-date information on the extent of the Nation's Internet adoption and the...

  10. Broadband Minimum Variance Beamforming for Ultrasound Imaging

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Gran, Fredrik; Jensen, Jørgen Arendt

    2009-01-01

    A minimum variance (MV) approach for near-field beamforming of broadband data is proposed. The approach is implemented in the frequency domain, and it provides a set of adapted, complex apodization weights for each frequency subband. The performance of the proposed MV beamformer is tested on...

  11. Fibre laser based broadband THz imaging systems

    DEFF Research Database (Denmark)

    Eichhorn, Finn

    State-of-the-art optical fiber technology can contribute towards complex multi-element broadband terahertz imaging systems. Classical table-top terahertz imaging systems are generally limited to a single emitter/receiver pair, which constrains their imaging capability to tedious raster scanning i...

  12. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

    Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted for...

  13. EMERGING BROADBAND WIRELESS TECHNOLOGIES: WIFI AND WIMAX

    Directory of Open Access Journals (Sweden)

    Rama K. Raju

    2012-07-01

    Full Text Available Now-a-days there is high demand for broadband mobile services. Traditional high-speed broadband solutions depend on wired technologies namely digital subscriber line (DSL. Wifi and Wimax are useful in providing any type of connectivity such as the fixed or portable or nomadic connectivity without the requirement of LoS (Line of Sight of the base station. Mobile Broadband Wireless Network (MBWN is a flexible and economical solution for remote areas where wired technology and also terminal mobility cannot be provided. The IEEE Wi-Fi and Wi-Max/802.16 are the most promising technologies for broadband wireless metropolitan area networks (WMANs and these are capable of providing high throughput even on long distances with varied QoS. These technologies ensure a wireless network that enables high speed Internet access to residential, small and medium business customers, as well as Internet access for WiFi hot spots and cellular base stations. These offer support to both point-to-multipoint (P2MP and multipoint-to-multipoint (mesh nodes and offers high speed data (voice, video service to the customers. In this paper, we study the issues related to, benefits and deployment of these technologies.

  14. Adjustable, Broadband, Selective Excitation with Uniform Phase

    Science.gov (United States)

    Cano, Kristin E.; Smith, Mari A.; Shaka, A. J.

    2002-03-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion.

  15. Broadband optical isolator in fibre optics

    OpenAIRE

    Berent, Michal; Rangelov, Andon A.; Vitanov, Nikolay V.

    2013-01-01

    We propose a broadband optical diode, which is composed of one achromatic reciprocal quarter-wave plate and one non-reciprocal quarter-wave plate, both placed between two crossed polarizers. The presented design of achromatic wave plates relies on an adiabatic evolution of the Stokes vector, thus, the scheme is robust and efficient. The possible simple implementation using fiber optics is suggested.

  16. Localization of aerial broadband noise by pinnipeds

    Science.gov (United States)

    Holt, Marla M.; Schusterman, Ronald J.; Southall, Brandon L.; Kastak, David

    2004-05-01

    Although many pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system, few studies have addressed these animals' ability to localize aerial broadband sounds. In this study, the aerial sound localization acuities of a female northern elephant seal (Mirounga angustirostris), a male harbor seal (Phoca vitulina), and a female California sea lion (Zalophus californianus) were measured in the horizontal plane. The stimulus was broadband white noise that was band pass filtered between 1.2 and 15 kHz. Testing was conducted in a hemi-anechoic chamber using a left/right forced choice procedure to measure the minimum audible angle (MAA) for each subject. MAAs were defined as half the angular separation of two sound sources bisected by a subject's midline that corresponded to 75% correct discrimination. MAAs were 4.7°, 3.6°, and 4.2° for the northern elephant seal, harbor seal, and California sea lion, respectively. These results demonstrate that individuals of these pinniped species have sound localization abilities comparable to the domestic cat and rhesus macaque. The acuity differences between our subjects were small and not predicted by head size. These results likely reflect the relatively acute general abilities of pinnipeds to localize aerial broadband signals.

  17. 77 FR 36903 - Accelerating Broadband Infrastructure Deployment

    Science.gov (United States)

    2012-06-20

    ... Infrastructure Development Through More Efficient and Effective Permitting and Environmental Review). (b) The..., Washington, June 14, 2012. [FR Doc. 2012-15183 Filed 6-19-12; 8:45 am] Billing code 3295-F2-P ... Documents#0;#0; ] Executive Order 13616 of June 14, 2012 Accelerating Broadband Infrastructure Deployment...

  18. Measuring sustainable broadband adoption: An innovative approach to understanding broadband adoption and use

    OpenAIRE

    Larose, Robert; De Maagd, Kurt; Chew, Han Ei; Tsai, Hsin-yi Sandy; Steinfield, Charles; Wildman, Steven S; Bauer, Johannes M.

    2012-01-01

    Efforts to promote sustainable broadband Internet adoption urge new attention to the classic diffusion of innovations paradigm. For this study, innovation attributes were reconceptualized following Social Cognitive Theory (SCT). In a sample of inner-city residents, the model accounted for 36% of the variance in intentions to adopt broadband technology and services, primarily from the SCT variables of expected outcomes and self-efficacy. Prior habitual use of the Internet was also a predictor....

  19. Investment in broadband infrastructure under local deregulation: Evidence from the UK broadband market

    OpenAIRE

    Fabritz, Nadine; Falck, Oliver

    2013-01-01

    This paper investigates telecommunication operator investment in broadband infrastructure after local deregulation of the wholesale broadband access market. Using a panel dataset covering all 5,598 exchange areas in the United Kingdom, we exploit regional differences in deregulation following a 2008 reform. Controlling for initial conditions, first-difference estimates show that local deregulation increases local investment in infrastructure by both the incumbent and competitors.

  20. The broadband debate: A documentary research on the broadband policy in Australia

    OpenAIRE

    Li, Grace

    2011-01-01

    Against a current trend of investing in the next generation networks (NGNs) by using public funds, the Australian government has recently initiated a so-called National Broadband Networks (NBN) project to invest up to AUD$36 billion tax payer's money on building a national wide fibre broadband network aiming to cover 93 per cent Australian by 2020. As being the most costly infrastructure-building project in Australian history, the NBN project will use a public-private-partnership as the instr...

  1. Broadband passive optical network media access control protocols

    Science.gov (United States)

    Quayle, Alan

    1996-11-01

    Most telecommunication operators are currently deciding on how to respond to customers' needs stimulated by the synergy between compression coding of multimedia and the emergence of broadband digital networks. This paper describes a range of broadband access architectures under consideration in the full services access network initiative. All architectures have a common requirement for a broadband ATM PON. A common broadband PON applicable to many operators increases the world-wide market for the product. With greater production volumes manufacturers' costs reduce because of the experience curve effect making broadband access systems economic.

  2. Management of broadband technology and innovation policy, deployment, and use

    CERN Document Server

    Choudrie, Jyoti

    2013-01-01

    When one considers broadband, the Internet immediately springs to mind. However, broadband is impacting society in many ways. For instance, broadband networks can be used to deliver healthcare or community related services to individuals who don't have computers, have distance as an issue to contend with, or don't use the internet. Broadband can support better management of scarce energy resources with the advent of smart grids, enables improved teleworking capacity and opens up a world of new entertainment possibilities. Yet scholarly examinations of broadband technology have so far examin

  3. Broadband Eclipse Spectra of Exoplanets are Featureless

    CERN Document Server

    Hansen, C J; Cowan, N B

    2014-01-01

    Spectral retrieval methods leverage features in emission spectra to constrain the atmospheric composition and structure of transiting exoplanets. Most of the observed emission spectra consist of broadband photometric observations at a small number of wavelengths. We compare the Bayesian Information Criterion (BIC) of blackbody fits and spectral retrieval fits for all planets with eclipse measurements in multiple thermal wavebands, typically hot Jupiters with 2-4 observations. If the published error bars are taken at face value, then eight planets are significantly better fit by a spectral model than by a blackbody. In this under-constrained regime, however, photometric uncertainties directly impact one's ability to constrain atmospheric properties. By considering the handful of planets for which eclipse measurements have been repeated and/or reanalyzed, we obtain an empirical estimate of systematic uncertainties for broadband eclipse depths obtained with the Spitzer Space Telescope: sigma_sys = 5E-4. When thi...

  4. Random Lasers for Broadband Directional Emission

    CERN Document Server

    Schönhuber, Sebastian; Hisch, Thomas; Deutsch, Christoph; Krall, Michael; Detz, Hermann; Strasser, Gottfried; Rotter, Stefan; Unterrainer, Karl

    2016-01-01

    Broadband coherent light sources are becoming increasingly important for sensing and spectroscopic applications, especially in the mid-infrared and terahertz (THz) spectral regions, where the unique absorption characteristics of a whole host of molecules are located. The desire to miniaturize such light emitters has recently lead to spectacular advances with compact on-chip lasers that cover both of these spectral regions. The long wavelength and the small size of the sources result in a strongly diverging laser beam that is difficult to focus on the target that one aims to perform spectroscopy with. Here, we introduce an unconventional solution to this vexing problem relying on a random laser to produce coherent broadband THz radiation as well as an almost diffraction limited far-field emission profile. Our random lasers do not require any fine-tuning and thus constitute a promising example of practical device applications for random lasing.

  5. A Broadband Dipolar Resonance in THz Metamaterials

    CERN Document Server

    Sangala, Bagvanth Reddy; Gopal, Achanta Venu; Prabhu, S S

    2014-01-01

    We demonstrate a THz metamaterial with broadband dipole resonance originating due to the hybridization of LC resonances. The structure optimized by finite element method simulations is fabricated by electron beam lithography and characterized by terahertz time-domain spectroscopy. Numerically, we found that when two LC metamaterial resonators are brought together, an electric dipole resonance arises in addition to the LC resonances. We observed a strong dependence of the width of these resonances on the separation between the resonators. This dependence can be explained based on series and parallel RLC circuit analogies. The broadband dipole resonance appears when both the resonators are fused together. The metamaterial has a stopband with FWHM of 0.47 THz centered at 1.12 THz. The experimentally measured band features are in reasonable agreement with the simulated ones. The experimental power extinction ratio of THz in the stopbands is found to be 15 dB.

  6. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  7. Techno-Economics of Residential Broadband Deployment

    DEFF Research Database (Denmark)

    Sigurdsson, Halldor Matthias

    2007-01-01

    of the proper broadband deployment strategy is depending on a complexed set of parameters, and there is a demand for precise techno-economic cost models estimating financial feasibility. The existing cost models do not consider the dynamic developments in the market caused by competition. The Ph...... economic and telecom regulation theory. Based upon this a techno-economic cost model is made that simulates capital expenses and services. As a special element of the model game theory is used to simulate the interaction between competitive infrastructures. The work has a specific focus on the Danish......PhD-projektet har titlen ”Techno-Economics of residential broadband deployment” (”Tekno-økonomisk analyse af bredbåndsforbindelser til private husstande”). Det omhandler den aktuelle markedssituation for bredbåndstjenester, hvor elselskaberne udfordrer de traditionelle teleselskaber ved massiv...

  8. Ultra-Broadband Coherent Supercontinuum Frequency Comb

    CERN Document Server

    Ruehl, Axel; Cossel, Kevin C; Chen, Lisheng; McKay, Hugh; Thomas, Brian; Benko, Craig; Dong, Liang; Dudley, John M; Fermann, Martin E; Hartl, Ingmar; Ye, Jun

    2011-01-01

    We present detailed studies of the coherence properties of an ultra-broadband super-continuum, enabled by a new approach involving continuous wave laser sources to independently probe both the amplitude and phase noise quadratures across the entire spectrum. The continuum coherently spans more than 1.5 octaves, supporting Hz-level comparison of ultrastable lasers at 698 nm and 1.54 {\\mu}m. We present the first numerical simulation of the accumulated comb coherence in the limit of many pulses, in contrast to the single-pulse level, with systematic experimental verification. The experiment and numerical simulations reveal the presence of quantum-seeded broadband amplitude noise without phase coherence degradation, including the discovery of a dependence of the super-continuum coherence on the fiber fractional Raman gain.

  9. Broad-band acoustic hyperbolic metamaterial

    CERN Document Server

    Shen, Chen; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-01-01

    Acoustic metamaterials (AMMs) are engineered materials, made from subwavelength structures, that exhibit useful or unusual constitutive properties. There has been intense research interest in AMMs since its first realization in 2000 by Liu et al. A number of functionalities and applications have been proposed and achieved using AMMs. Hyperbolic metamaterials are one of the most important types of metamaterials due to their extreme anisotropy and numerous possible applications, including negative refraction, backward waves, spatial filtering, and subwavelength imaging. Although the importance of acoustic hyperbolic metamaterials (AHMMs) as a tool for achieving full control of acoustic waves is substantial, the realization of a broad-band and truly hyperbolic AMM has not been reported so far. Here, we demonstrate the design and experimental characterization of a broadband AHMM that operates between 1.0 kHz and 2.5 kHz.

  10. Broadband single-molecule excitation spectroscopy

    Science.gov (United States)

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F.

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy.

  11. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  12. The EarthCARE broadband radiometer detectors

    Science.gov (United States)

    Proulx, Christian; Williamson, Fraser; Allard, Martin; Baldenberger, Georges; Gay, David; Garcia-Blanco, Sonia; Côté, Patrice; Martin, Louis; Larouche, Carl; Ilias, Samir; Pope, Tim; Caldwell, Martin; Ward, Kim; Delderfield, John

    2009-08-01

    The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide top-of-atmosphere (TOA) radiance measurements in two spectral channels, and over three along-track directions. The instrument has three fixed telescopes (one for each view) each containing a broadband detector. Each detector consists of an uncooled 30-pixel linear focal plane array (FPA) coated with gold black in order to ensure uniform spectral responsivity from 0.2 μm to 50 μm. The FPA is hybridized with a readout integrated circuit (ROIC) and a proximity electronics circuit-card assembly (CCA) packaged in an aluminum base plate with cover. This paper provides a technical description of the detector design and operation. Performance data at the FPA pixel level as well as unit-level test results on early prototypes of the detectors are also presented.

  13. Integrated broadband bowtie antenna on transparent substrate

    CERN Document Server

    Zhang, Xingyu; Subbaraman, Harish; Zhan, Qiwen; Pan, Zeyu; Chung, Chi-jui; Yan, Hai; Chen, Ray T

    2015-01-01

    The bowtie antenna is a topic of growing interest in recent years. In this paper, we design, fabricate, and characterize a modified gold bowtie antenna integrated on a transparent glass substrate. We numerically investigate the antenna characteristics, specifically its resonant frequency and enhancement factor. We simulate the dependence of resonance frequency on bowtie geometry, and verify the simulation results through experimental investigation, by fabricating different sets of bowtie antennas on glass substrates utilizing CMOS compatible processes and measuring their resonance frequencies. Our designed bowtie antenna provides a strong broadband electric field enhancement in its feed gap. The far-field radiation pattern of the bowtie antenna is measured, and it shows dipole-like characteristics with large beam width. Such a broadband antenna will be useful for a myriad of applications, ranging from wireless communications to electromagnetic wave detection.

  14. Broadband Visible Light Induced NO Formation

    Science.gov (United States)

    Lubart, Rachel; Eichler, Maor; Friedmann, Harry; Savion, N.; Breitbart, Haim; Ankri, Rinat

    2009-06-01

    Nitric oxide formation is a potential mechanism for photobiomodulation because it is synthesized in cells by nitric oxide synthase (NOS), which contains both flavin and heme, and thus absorbs visible light. The purpose of this work was to study broadband visible light induced NO formation in various cells. Cardiac, endothelial, sperm cells and RAW 264.7 macrophages were illuminated with broadband visible light, 40-130 mW/cm2, 2.4-39 J/cm2, and nitric oxide production was quantified by using the Griess reagent. The results showed that visible light illumination increased NO concentration both in sperm and endothelial cells, but not in cardiac cells. Activation of RAW 264.7 macrophages was very small. It thus appears that NO is involved in photobiomodulation, though different light parameters and illumination protocols are needed to induce NO in various cells.

  15. Broadband Visible Light Induced NO Formation

    International Nuclear Information System (INIS)

    Nitric oxide formation is a potential mechanism for photobiomodulation because it is synthesized in cells by nitric oxide synthase (NOS), which contains both flavin and heme, and thus absorbs visible light. The purpose of this work was to study broadband visible light induced NO formation in various cells. Cardiac, endothelial, sperm cells and RAW 264.7 macrophages were illuminated with broadband visible light, 40-130 mW/cm2, 2.4-39 J/cm2, and nitric oxide production was quantified by using the Griess reagent. The results showed that visible light illumination increased NO concentration both in sperm and endothelial cells, but not in cardiac cells. Activation of RAW 264.7 macrophages was very small. It thus appears that NO is involved in photobiomodulation, though different light parameters and illumination protocols are needed to induce NO in various cells.

  16. Household Demand for Broadband Internet in 2010

    OpenAIRE

    Rosston Gregory L.; Savage Scott J; Waldman Donald M.

    2010-01-01

    This paper uses data from a nationwide survey administered during late 2009 and early 2010 to estimate a random utility model of household preferences for broadband Internet service. Reliability and speed are important service characteristics: the representative household is willing to pay $20 per month for more reliable service; $45 for an improvement in speed from slow to fast; and $48 for an improvement in speed from slow to very fast. A representative household would be willing to pay $79...

  17. Broadband phase-preserved optical elevator

    OpenAIRE

    Luo, Yuan; Han, Tiancheng; Zhang, Baile; Qiu, Cheng-Wei; Barbastathis, George

    2011-01-01

    Phase-preserved optical elevator is an optical device to lift up an entire plane virtually without distortion in light path or phase. Using transformation optics, we have predicted and observed the realization of such a broadband phase-preserved optical elevator, made of a natural homogeneous birefringent crystal without resorting to absorptive and narrowband metamaterials involving time-consuming nano-fabrication. In our demonstration, the optical elevator is designed to lift a sheet upwards...

  18. Broadband Waveguide QED System on a Chip

    OpenAIRE

    Quan, Qimin; Bulu, Irfan; Loncar, Marko

    2009-01-01

    We demonstrate that a slot waveguide provides a broadband loss-free platform suitable for applications in quantum optics. We find that strong coupling between light quanta and a single quantum emitter placed in the waveguide slot can be achieved with efficiency higher than 96% and Purcell factor (spontaneous emission factor) larger than 200. The proposed system is a promising platform for quantum information processing and can be used to realize an efficient single photon source and optically...

  19. Broadband high efficiency active integrated antenna

    OpenAIRE

    Qin, Yi

    2007-01-01

    Active integrated antenna (MA) is a very popular topic of research during recent decades. This is mostly due to its advantages, such as compact size, multiple functions and low cost, etc. The MA system can be regarded as an active microwave circuit which the output or input port is free space instead of a conventional 50-ohm interface. The major drawbacks of the conventional MA include narrow bandwidth, low efficiency, etc. An experimental investigation on broadband slot-coupled antenna is ca...

  20. Circularly Polarized Broadband RFID Microstrip Tag Antenna

    OpenAIRE

    B. Rajini; G. V. Subrahmanyam

    2014-01-01

    In recent years, the application of radio frequency identification (RFID) operating in the ultra-high frequency (UHF) band (860-960MHz) are expanding exponentially, due to the advantages such as long reading distance, high data transfer rate, and small tag size. So the design of a CP tag antenna with broadband characteristic is presently one of the most challenging topics. This project presents a square patch passive RFID tag antenna designed for UHF band. To a...

  1. A Broadband Dipolar Resonance in THz Metamaterials

    OpenAIRE

    Sangala, Bagvanth Reddy; Surdi, Harshad; Gopal, Achanta Venu; Prabhu, S. S.

    2014-01-01

    We demonstrate a THz metamaterial with broadband dipole resonance originating due to the hybridization of LC resonances. The structure optimized by finite element method simulations is fabricated by electron beam lithography and characterized by terahertz time-domain spectroscopy. Numerically, we found that when two LC metamaterial resonators are brought together, an electric dipole resonance arises in addition to the LC resonances. We observed a strong dependence of the width of these resona...

  2. Mobility Extension for Broadband Satellite Multimedia

    OpenAIRE

    Hu, Y.Fun; Pillai, Prashant; Berioli, Matteo

    2009-01-01

    This paper presents an extension for Broadband Satellite Multimedia (BSM) to support Mobility Management (MM). To support seamless handovers, mobility related entities are proposed in the Satellite Independent Access Function (SIAF) defined over the SI-SAP interface. This enables the mapping of the mobility related primitives between the higher layer and the satellite dependant lower layers via the Satellite Dependent Access Function (SDAF). The proposed MM architecture incorporates the Media...

  3. Telecommunication policies for broadband access networks

    OpenAIRE

    Pereira, João Paulo

    2009-01-01

    The "triple play" services required (Internet, telephone and TV services) lead to a great increase in bandwidth demand. However, the existing access networks are not able to support this increase, and the capacity to delivery broadband services remain as a challenge ("last mile problem"). The access network remains a bottleneck in terms of the bandwidth and service quality it affords the end user. Besides the bandwidth, other great challenge to access networks is the mobility and the user nee...

  4. Broadband Approximations for Doubly Curved Reflector Antenna

    OpenAIRE

    V. Schejbal; J. Pidanic

    2010-01-01

    The broadband approximations for shaped-beam doubly curved reflector antennas with primary feed (rectangular horn) producing uniform amplitude and phase aperture distribution are derived and analyzed. They are very valuable for electromagnetic compatibility analyses both from electromagnetic interference and susceptibility point of view, because specialized more accurate methods such as physical optics are only used by antenna designers. To allow quick EMC analyses, typical values, beamwidth ...

  5. Rural Broadband Internet Access Supply and Demand

    OpenAIRE

    Stenberg, Peter L.; Morehart, Mitchell J.

    2009-01-01

    Internet use has grown rapidly over the last 15 years and so has its integration into the rural economy. Connecting to the Internet via high-speed technology such as DSL lines, cable, satellite, and wireless networks increases bandwidth and makes the Internet much more useful to businesses, households, and governments. Rural households are almost as likely as urban households to use the Internet. Broadband Internet access in rural areas has been less prevalent than in much more densely popula...

  6. Switched Broadband Services For The Home

    Science.gov (United States)

    Sawyer, Don M.

    1990-01-01

    In considering the deployment of fiber optics to the residence, two critical questions arise: what are the leading services that could be offered to justify the required investment; and what is the nature of the business that would offer these services to the consumer ? This talk will address these two questions together with the related issue of how the "financial engine" of today's television distribution infrastructure - TV advertising - would be affected by an open access system based on fiber optics coupled with broadband switching. On the business side, the talk concludes that the potential for open ended capacity expansion, fair competition between service providers, and new interactive services inherent in an open access, switched broadband system are the critical items in differentiating it from existing video and TV distribution systems. On the question of broadband services, the talk will highlight several new opportunities together with some findings from recent market research conducted by BNR. The talk will show that there are variations on existing services plus many new services that could be offered and which have real consumer appeal. The postulated open access system discussed here is visualized as having ultimately 1,000 to 2,000 video channels available to the consumer. Although this may appear to hopelessly fragment the TV audience and destroy the current TV advertising infrastructure, the technology of open access, switched broadband will present many new advertising techniques, which have the potential to be far more effective than those available today. Some of these techniques will be described in this talk.

  7. Broadband Wireless Access in Disaster Emergency Response

    OpenAIRE

    Bai, Xin

    2006-01-01

    The “WLAN in Disaster Emergency Response” (WIDER) project has developed and implemented an emergency communication system. It provides network and communication services to relief organizations. In order to guarantee the stable and efficient connectivity with a high quality of service (QoS) for the end user, and to make the WIDER system more adaptive to the disaster area, the IEEE 802.16 specification based broadband wireless access solution is adopted. This thesis work aims at evaluating and...

  8. Broadband absorption engineering of hyperbolic metafilm patterns

    OpenAIRE

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-01-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experime...

  9. Design of broadband single polarized antenna

    Science.gov (United States)

    Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

    2015-05-01

    In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

  10. Broadband: What do consumers want? Examining willingness-to-pay

    OpenAIRE

    Klie, Adrian

    2013-01-01

    Recently, fourth-generation mobile networks have gained traction. Those new mobile services offer speed comparable to existing fixed broadband access. This convergence in speed of mobile and fixed broadband puts in question the need for consumers to be subscribed to two separate services for fixed and mobile access. This study investigates the willingness-to-pay for mobile broadband as well as consumers' willingness to give up speed for the flexibility of having their “regular” in...

  11. Broadband Infrastructure and Entrepreneurship: Evidence from German Municipalities

    OpenAIRE

    Falck, Oliver; Mazat, Andreas; Stockinger, Bastian

    2015-01-01

    Policy makers in many places regularly call for broadband infrastructure deployment to foster regional development. While some empirical studies deal with the productivity impact of broadband Internet availability, few hard facts are known about its relation to establishment start-up. This paper contributes to closing the gap, providing causal evidence on the impact of broadband Internet availability on establishment start-up. We apply an instrumental variables approach, exploiting technologi...

  12. Socio-Economic Assessment of Broadband Development in Egypt

    OpenAIRE

    World Bank

    2010-01-01

    The Government of Egypt has recognized broadband as being of strategic importance to the country´s economic and social development and it is developing a new strategy to develop access and use of broadband networks and services. As a specific target of this strategy, the government seeks to increase broadband penetration to 20 connections per 100 inhabitants by 2013. This report is the res...

  13. Incoherent broadband optical pulse generation using an optical gate

    Institute of Scientific and Technical Information of China (English)

    Biao Chen; Qiong Jiang

    2008-01-01

    In two-dimensional (2D) time-spreading/wavelength-hopping optical code division multiple access (OCDMA) systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and better system performance. An optical gate based scheme for generating weakly coherent(approximately incoherent) broadband optical pulses was proposed and experimentally demonstrated. Inthis scheme, the terahertz optical asymmetric demultiplexer, together with a coherent narrowband controlpulse source, turns an incoherent broadband continuous-wave (CW) light source into the required pulse source.

  14. Denial of service attacks and challenges in broadband wireless networks

    OpenAIRE

    Khan, S.; Loo, KK; Naeem, T; Khan, MA

    2008-01-01

    Broadband wireless networks are providing internet and related services to end users. The three most important broadband wireless technologies are IEEE 802.11, IEEE 802.16, and Wireless Mesh Network (WMN). Security attacks and vulnerabilities vary amongst these broadband wireless networks because of differences in topologies, network operations and physical setups. Amongst the various security risks, Denial of Service (DoS) attack is the most severe security threat, as DoS can compromis...

  15. Broadband Faraday isolator for gravitational wave detectors

    CERN Document Server

    Parfenov, V A

    2002-01-01

    In this paper, we report on the concept and performance of a highly effective broadband Faraday isolator. This device is based on Nd:Fe:B permanent magnets and can be used in interferometric gravitational wave detectors in which lasers oscillating in the visible or near infrared region are used. The degree of optical isolation of 30 dB, provided by the device, is achieved when operating with laser beams of up to 2 mm, and up to 25 dB when the aperture of the magneto-optic element (10 mm) is completely filled.

  16. Ultra-broadband Microwave Metamaterial Absorber

    CERN Document Server

    Ding, Fei; Ge, Xiaochen; Jin, Yi; He, Sailing

    2012-01-01

    A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes at multi-frequencies, of which the overlapping leads to the total absorption of the incident wave over an ultra-wide spectral band. The experimental absorption at normal incidence is above 90% in the frequency range of 7.8-14.7GHz, and the absorption is kept large when the incident angle is smaller than 60 degrees. The experimental results agree well with the numerical simulation.

  17. Cascaded frequency doublers for broadband laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N F; Vlasova, K V; Davydov, V S; Kulikov, S M; Makarov, A I; Sukharev, Stanislav A; Freidman, Gennadii I; Shubin, S V

    2012-10-31

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband ({approx}33 cm{sup -1}) single-mode fibre laser radiation with low peak power ({approx}300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency {eta} = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to {approx}30 %. (nonlinear optical phenomena)

  18. Cascaded frequency doublers for broadband laser radiation

    Science.gov (United States)

    Andreev, N. F.; Vlasova, K. V.; Davydov, V. S.; Kulikov, S. M.; Makarov, A. I.; Sukharev, Stanislav A.; Freidman, Gennadii I.; Shubin, S. V.

    2012-10-01

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband (~33 cm-1) single-mode fibre laser radiation with low peak power (~300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency η = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to ~30 %.

  19. Broadband surface-wave transformation cloak.

    Science.gov (United States)

    Xu, Su; Xu, Hongyi; Gao, Hanhong; Jiang, Yuyu; Yu, Faxin; Joannopoulos, John D; Soljačić, Marin; Chen, Hongsheng; Sun, Handong; Zhang, Baile

    2015-06-23

    Guiding surface electromagnetic waves around disorder without disturbing the wave amplitude or phase is in great demand for modern photonic and plasmonic devices, but is fundamentally difficult to realize because light momentum must be conserved in a scattering event. A partial realization has been achieved by exploiting topological electromagnetic surface states, but this approach is limited to narrow-band light transmission and subject to phase disturbances in the presence of disorder. Recent advances in transformation optics apply principles of general relativity to curve the space for light, allowing one to match the momentum and phase of light around any disorder as if that disorder were not there. This feature has been exploited in the development of invisibility cloaks. An ideal invisibility cloak, however, would require the phase velocity of light being guided around the cloaked object to exceed the vacuum speed of light--a feat potentially achievable only over an extremely narrow band. In this work, we theoretically and experimentally show that the bottlenecks encountered in previous studies can be overcome. We introduce a class of cloaks capable of remarkable broadband surface electromagnetic waves guidance around ultrasharp corners and bumps with no perceptible changes in amplitude and phase. These cloaks consist of specifically designed nonmagnetic metamaterials and achieve nearly ideal transmission efficiency over a broadband frequency range from 0(+) to 6 GHz. This work provides strong support for the application of transformation optics to plasmonic circuits and could pave the way toward high-performance, large-scale integrated photonic circuits. PMID:26056299

  20. Circularly Polarized Broadband RFID Microstrip Tag Antenna

    Directory of Open Access Journals (Sweden)

    B. Rajini

    2014-04-01

    Full Text Available In recent years, the application of radio frequency identification (RFID operating in the ultra-high frequency (UHF band (860-960MHz are expanding exponentially, due to the advantages such as long reading distance, high data transfer rate, and small tag size. So the design of a CP tag antenna with broadband characteristic is presently one of the most challenging topics. This project presents a square patch passive RFID tag antenna designed for UHF band. To achieve compact size broadband and circular polarization (CP radiation, the square patch is embedded with a cross slot, while an L-shaped open-end microstrip line coupled to the patch. By selecting an appropriate length for the microstrip line and its coupling distance with the radiating element, easy control on the input impedance of the designed tag antenna which leads to excellent impedance matching is achieved. The measured 10-dB return-loss bandwidth of the tag antenna is 27MHz (from 901–928 MHz.

  1. Broadband acoustic properties of a murine skull

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Turner, Jake; Razansky, Daniel

    2016-03-01

    It has been well recognized that the presence of a skull imposes harsh restrictions on the use of ultrasound and optoacoustic techniques in the study, treatment and modulation of the brain function. We propose a rigorous modeling and experimental methodology for estimating the insertion loss and the elastic constants of the skull over a wide range of frequencies and incidence angles. A point-source-like excitation of ultrawideband acoustic radiation was induced via the absorption of nanosecond duration laser pulses by a 20 μm diameter microsphere. The acoustic waves transmitted through the skull are recorded by a broadband, spherically focused ultrasound transducer. A coregistered pulse-echo ultrasound scan is subsequently performed to provide accurate skull geometry to be fed into an acoustic transmission model represented in an angular spectrum domain. The modeling predictions were validated by measurements taken from a glass cover-slip and ex vivo adult mouse skulls. The flexible semi-analytical formulation of the model allows for seamless extension to other transducer geometries and diverse experimental scenarios involving broadband acoustic transmission through locally flat solid structures. It is anticipated that accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in a broad variety of applications employing transcranial detection or transmission of high frequency ultrasound.

  2. A novel broadband circularly polarised monopole antenna

    Science.gov (United States)

    Kang, Ding; Cheng, Gao; Tongbin, Yu; Dexin, Qu

    2015-11-01

    A novel broadband circularly polarised (CP) monopole antenna is designed and implemented in this article. The antenna consists of a radiating patch that is composed of an annular-ring linked by a square ring over the corner and a modified ground plane. The broadband property is achieved based on a novel monopole structure that is connected by two perturbed loops, so the CP wave is generated due to the perturbation. Besides, by cutting a rectangular slit and embedding a vertical stub on the ground plane, the impedance and axial-ratio (AR) bandwidths can be greatly enhanced. The measured results reveal that the proposed monopole antenna has an impedance bandwidth of 4.575 GHz from 2.3 to 6.85 GHz, reaching the particularly broad bandwidth of 99.5%. Furthermore, a wide 3-dB AR bandwidth of 34.6% (1.53 GHz, 3.65-5.18 GHz) centred at 4.42 GHz is achieved. The radiation characteristics of the designed antenna are also presented.

  3. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

    Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.

  4. 77 FR 14340 - Proposed Information Collection; Comment Request; Broadband Technology Opportunities Program...

    Science.gov (United States)

    2012-03-09

    ... of automated collection techniques or other forms of information technology. Comments submitted in...; Broadband Technology Opportunities Program (BTOP) Quarterly and Annual Performance Progress Reports AGENCY... broadband service to underserved areas of the country; (3) To provide broadband access, education,...

  5. The role of public initiatives facilitating investments in broadband infrastructures

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza; Henten, Anders;

    2015-01-01

    This paper discusses the role of a developmental approach to broadband policy. The policy approaches made in Denmark and Sweden are compared, and the scope for public intervention at the broadband market is discussed. The paper includes a case study on public intervention in the rural areas of the...

  6. A broadband, high-resolution spatial heterodyne spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J E; Roesler, F L; Labby, Z [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Harlander, J [Department of Physics, Astronomy, and Engineering Science, St. Cloud State University, St. Cloud, MN 56301 (United States)], E-mail: jelawler@wisc.edu

    2009-05-15

    Design and performance parameters of a broadband, high-resolution spatial heterodyne spectrometer (SHS) with a transmitting beamsplitter are described. This Mark 1 SHS achieves more than a factor of five in continuous wavenumber coverage with a resolving power in hundreds of thousands. Progress toward an all reflection, broadband, high-resolution Mark 2 SHS is reported.

  7. 78 FR 8353 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2013-02-06

    ... Service concluded that broadband investment in rural areas yields significant economic and socio-economic..., economic, and social factors can overcome common barriers to broadband expansion. In general, rural America... referred to as the Agency, is adopting as final, with change, an interim rule (published at 76 FR 13770...

  8. 78 FR 25787 - Community Connect Broadband Grant Program

    Science.gov (United States)

    2013-05-03

    ... Sec. 1739.1 Purpose. (a) The provision of broadband service is vital to the economic development... overlap with the service areas of current RUS borrowers and grantees. Sec. 1739.12 Eligible grant purposes... CFR Part 1739 RIN 0572-AC30 Community Connect Broadband Grant Program AGENCY: Rural Utilities...

  9. Silicon graphene waveguide tunable broadband microwave photonics phase shifter

    OpenAIRE

    Capmany, Jose; Domenech, David; Muñoz, Pascual

    2013-01-01

    We propose the use of silicon graphene waveguides to implement a tunable broadband microwave photonics phase shifte based on integrated ring cavities. Numerical computation results show the feasibility for broadband operation over 40 GHz bandwidth and full 360 degree radiofrequency phase-shift with a modest voltage excursion of 0.12 volt.

  10. Silicon graphene waveguide tunable broadband microwave photonics phase shifter.

    Science.gov (United States)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-04-01

    We propose the use of silicon graphene waveguides to implement a tunable broadband microwave photonics phase shifter based on integrated ring cavities. Numerical computation results show the feasibility for broadband operation over 40 GHz bandwidth and full 360° radiofrequency phase-shift with a modest voltage excursion of 0.12 volt. PMID:24718185

  11. Techno-economic evaluation of broadband access technologies

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias; Skouby, Knud Erik

    2005-01-01

    Broadband for all is an essential element in the EU policy concerning the future of ICT-based society. The overall purpose of this paper is to present a model for evaluation of different broadband access technologies and to present some preliminary results based on the model that has been carried...

  12. Broadband Optical Access Technologies to Converge towards a Broadband Society in Europe

    Science.gov (United States)

    Coudreuse, Jean-Pierre; Pautonnier, Sophie; Lavillonnière, Eric; Didierjean, Sylvain; Hilt, Benoît; Kida, Toshimichi; Oshima, Kazuyoshi

    This paper provides insights on the status of broadband optical access market and technologies in Europe and on the expected trends for the next generation optical access networks. The final target for most operators, cities or any other player is of course FTTH (Fibre To The Home) deployment although we can expect intermediate steps with copper or wireless technologies. Among the two candidate architectures for FTTH, PON (Passive Optical Network) is by far the most attractive and cost effective solution. We also demonstrate that Ethernet based optical access network is very adequate to all-IP networks without any incidence on the level of quality of service. Finally, we provide feedback from a FTTH pilot network in Colmar (France) based on Gigabit Ethernet PON technology. The interest of this pilot lies on the level of functionality required for broadband optical access networks but also on the development of new home network configurations.

  13. Broadband Dielectric Spectroscopy on Human Blood

    CERN Document Server

    Wolf, M; Lunkenheimer, P; Loidl, A

    2011-01-01

    Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of variou...

  14. Broadband Multifocal Conic-Shaped Metalens

    CERN Document Server

    Bao, Yanjun; Fang, Zheyu

    2016-01-01

    Compared with lens with one focal point,multifocal lens has a lower focusing quality with high background noise. This is arisen from the construction of multifocal lens, which is usually divided into several zones, with each corresponds to one focal point.Light passing through different zones cannot constructively interfere at the foci, resulting in a decreased optical performance. Here, we propose two multifocal metalenses with nanoslits arranged in an ellipse and a hyperbola, with both are able to focus incident light at their multifoci constructively, giving a better focusing properties than that designed by conventional methods.We theoretically and experimentally demonstrate that, within a broadband wavelength range (600-900 nm), the ellipse-shaped metalens (ESM) can focus the lights with opposite circular polarizations (CP) at its two focal points, respectively,while a hyperbola-shaped metalens (HSM) can only focus one particular CP light at its both foci, simultaneously.This types of conic-shaped metale...

  15. Ultra-broadband terahertz metamaterial absorber

    Science.gov (United States)

    Zhu, Jianfei; Ma, Zhaofeng; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

    2014-07-01

    We demonstrated an ultra-broadband, polarization-insensitive, and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design, each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21 μm is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40°. The full absorption width at half maximum of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

  16. Broadband optical cooling of molecular rotors

    CERN Document Server

    Lien, Chien-Yu; Odom, Brian C

    2014-01-01

    Contrary to intuition, resonant laser excitation of bound electrons can decrease the temperature of a system, with electronic relaxation times as fast as nanoseconds allowing for rapid cooling to far below ambient temperature. Although laser cooling of atoms is routine owing to their relatively simple internal structure, laser cooling of molecular translational speeds, vibrations, or rotations is challenging because a different laser frequency is required to electronically excite each populated vibrational and rotational state. Here, we show that molecules with decoupled vibrational and electronic modes can be rotationally cooled using a single spectrally filtered broadband laser to simultaneously address many rotational states. We optically cool AlH$^+$ ions held in a room-temperature radiofrequency Paul trap to collect 96% of the population in the ground quantum state, corresponding to a rotational temperature of 4 K. In our current implementation, parity-preserving electronic cycling cools to the two lowes...

  17. Frequency Doubling Broadband Light in Multiple Crystals

    International Nuclear Information System (INIS)

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth

  18. Broadband phase-preserved optical elevator

    CERN Document Server

    Luo, Yuan; Zhang, Baile; Qiu, Cheng-Wei; Barbastathis, George

    2011-01-01

    Phase-preserved optical elevator is an optical device to lift up an entire plane virtually without distortion in light path or phase. Using transformation optics, we have predicted and observed the realization of such a broadband phase-preserved optical elevator, made of a natural homogeneous birefringent crystal without resorting to absorptive and narrowband metamaterials involving time-consuming nano-fabrication. In our demonstration, the optical elevator is designed to lift a sheet upwards, and the phase is verified to be preserved always. The camouflage capability is also demonstrated in the presence of adjacent objects of the same scale at will. The elevating device functions in different surrounding media over the wavelength range of 400-700 nm. Our work opens up prospects for studies of light trapping, solar energy, illusion optics, communication, and imaging.

  19. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua

    2013-04-25

    Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range. © 2013 IOP Publishing Ltd.

  20. Broad-band multisection electrooptic modulators

    Science.gov (United States)

    Lax, Benjamin; Marino, Richard M.; Eng, Richard S.

    1988-10-01

    A general solution has been derived for expressing the conversion of power from a base frequency to a modulation sideband using a multisection electrooptic modulator. The objective is to obtain broadband frequency modulation of a laser by the use of multiple collinear electrooptic crystals with microwave power levels well below the breakdown threshold. It is found that segmented structures lead to greater bandwidths, which increase with the number of modulator sections. This is achieved by adjusting the phases of microwaves between sections to maximize the single-sideband conversion efficiency. It is shown that a 10.6-micron CO2 laser modulator with six geometrically identical CdTe sections can potentially achieve a 3-dB bandwidth of nearly 6 GHz using a 10-kW traveling-wave tube operating at 16-GHz center frequency.

  1. Statistical dispersion relation for spatially broadband fields.

    Science.gov (United States)

    Shan, Mingguang; Nastasa, Viorel; Popescu, Gabriel

    2016-06-01

    The dispersion relation is fundamental to a physical phenomenon that develops in both space and time. This equation connects the spatial and temporal frequencies involved in the dynamic process through the material constants. Electromagnetic plane waves propagating in homogeneous media are bound by simple dispersion relation, which sets the magnitude of the spatial frequency, k, as being proportional to the temporal frequency, ω, with the proportionality constant dependent on the refractive index, n, and the speed of light in vacuum, c. Here we show that, for spatially broadband fields, an analog dispersion relation can be derived, except in this case the k-vector variance is connected with the temporal frequency through the statistics of the refractive index fluctuations in the medium. We discuss how this relationship can be used to retrieve information about refractive index distributions in biological tissues. This result is particularly significant in measurements of angular light scattering and quantitative phase imaging of biological structures. PMID:27244396

  2. Policy factors affecting broadband development in Poland

    DEFF Research Database (Denmark)

    Henten, Anders; Windekilde, Iwona Maria

    2014-01-01

    gradually change the previous balance of power. The specific problem of the Polish market is its very poor infrastructure development and the lack of competitors on the fixed market. This translates into limited access to services for end users particularly in the rural areas. A much lower level of......’s telecommunications market with the European market. The market reflects all the global trends, a gradually growing significance of mobile telecommunications services, broadband Internet access, construction of offers directed towards clients’ needs, and a strong trend towards market consolidation, which will...... telecommunications network development in Poland than other countries in the European Union is the reason that the circumstances and also the effects of the implementation of some solutions of the EU regulation model are different in Poland than in the most developed EU countries. The aim of the paper is to examine...

  3. On helicopter rotor low frequency broadband noise

    Science.gov (United States)

    Williams, Morgan; Harris, Wesley L.

    1985-01-01

    The effect of shear-layer-type inflow turbulence on the low-frequency broadband noise of a model helicopter rotor is experimentally studied. The measurements and the one-dimensional energy spectral density indicate that the upstream airfoil wake turbulence is nonisotropic, but approaches isotropy at high wavenumbers. Turbulence measurements also indicate that the wake turbulence is weak. The effect of the inflow turbulence intensity on the peak sound pressure level follows an intensity-velocity squared scaling law. A number of length scales and turbulence intensities exist which can be measured in the airfoil wake depending on the position at which the measurements are taken. Comparison of experimental and theoretical sound pressure power spectral densities indicates that the initial anisotropy of the inflow turbulence does not invalidate the isotropic turbulence assumption made in noise prediction models as long as measured turbulence intensities and length scales are used.

  4. Model helicopter rotor low frequency broadband noise

    Science.gov (United States)

    Humbad, N. G.; Harris, W. L.

    1982-01-01

    The results of an experimental investigation of low frequency broadband noise (LFBN) radiated from model helicopter rotors are presented. The results up to tip Mach number of 0.50 suggest that the peak sound pressure level (SPL) of LFBN appears to follow tip Mach number to a fourth power law and rms velocity of turbulence to a second power law. The experimental results on the effect of tip speed and advance ratio on the peak SPL of LFBN can be explained on the basis of a simple scaling law. However, the experimental results on the effect of blade loading on the peak SPL of LFBN is still not clearly understood. A simple peak SPL scaling law for noise from a helicopter in forward flight encountering a sinusoidal gust is also developed. The trends predicted by the scaling law with the experimental results are found satisfactory for the cases of variation of the peak SPL of LFBN with tip speed and advance ratio.

  5. Broadband Approximations for Doubly Curved Reflector Antenna

    Directory of Open Access Journals (Sweden)

    V. Schejbal

    2010-12-01

    Full Text Available The broadband approximations for shaped-beam doubly curved reflector antennas with primary feed (rectangular horn producing uniform amplitude and phase aperture distribution are derived and analyzed. They are very valuable for electromagnetic compatibility analyses both from electromagnetic interference and susceptibility point of view, because specialized more accurate methods such as physical optics are only used by antenna designers. To allow quick EMC analyses, typical values, beamwidth changes, sidelobe levels and aperture efficiencies are given for frequency changes approximately up to four times operating frequency. A comparison of approximated and measured patterns of doubly curved reflector antennas shows that the given approximation could be reliably used for analyses of pattern changes due to very broad frequency changes.

  6. Future large broadband switched satellite communications networks

    Science.gov (United States)

    Staelin, D. H.; Harvey, R. R.

    1979-01-01

    Critical technical, market, and policy issues relevant to future large broadband switched satellite networks are summarized. Our market projections for the period 1980 to 2000 are compared. Clusters of switched satellites, in lieu of large platforms, etc., are shown to have significant advantages. Analysis of an optimum terrestrial network architecture suggests the proper densities of ground stations and that link reliabilities 99.99% may entail less than a 10% cost premium for diversity protection at 20/30 GHz. These analyses suggest that system costs increase as the 0.6 power of traffic. Cost estimates for nominal 20/30 GHz satellite and ground facilities suggest optimum system configurations might employ satellites with 285 beams, multiple TDMA bands each carrying 256 Mbps, and 16 ft ground station antennas. A nominal development program is outlined.

  7. Michelson interferometer diagnostics for broadband ECE measurement

    International Nuclear Information System (INIS)

    A Michelson interferometer (MI) diagnostic is capable of measuring broadband intensity spectra in the microwave and near infrared spectral range. The Michelson interferometer diagnostics is dedicated to probe the full electron cyclotron emission (ECE) spectrum emitted by plasmas in tokamak experiments with magnetic confinement. At the SST-1 Tokamak at IPR, Michelson interferometer will be used to measure the spectrum of the electron cyclotron emission in the spectral range 70-500 GHz. The interferometer is absolutely calibrated using the hot/cold technique and, in consequence, the spatial profile of the plasma electron temperature is determined from the measurements. The Michelson interferometer has spectral resolution of 3.66 GHz and temporal resolution of about 16.67 ms. Installation of the Michelson interferometer diagnostics is in process at IPR. (author)

  8. Hot Carrier extraction with plasmonic broadband absorbers

    CERN Document Server

    Ng, Charlene; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gomez, Daniel E

    2016-01-01

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to $\\sim$ 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the S...

  9. Designing Broadband Access Networks with Triple Redundancy

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Riaz, Muhammad Tahir; Knudsen, Thomas Phillip;

    2005-01-01

    An architecture is proposed for designing broadband access networks, which offer triple redundancy to the end users, resulting in networks providing connectivity even in case of any two independent node or line failures. Two physically independent connections are offered by fiber, and the last...... provided by some wireless solution. Based on experience with planning Fiber To The Home, the architecture is designed to meet a number of demands, making it practicable and useful in realworld network planning. The proposed wired topology is planar, and suitable for being fitted onto the road network...... without compromising line independency, and it can be implemented stepwise, the first step being based on a simple ring/tree topology. The double ring is used for the distribution network, ensuring 3-connectivity and making it feasible to use for connecting the base stations of the wireless network...

  10. Local Implementation of a Broadband Network: Social Impact issues of New Broadband Capacity in Australia

    OpenAIRE

    Tiffany Amber Tenty; Brendan Wallis; Sumita Ghosh; Richard Howitt

    2012-01-01

    In April 2009, the Australian Government announced plans to roll-out the National Broadband Network (NBN) Company Open Access Network in Australia. Australia’s NBN will bring high speed internet access to areas and people that otherwise would have been without. Predicting consequences (both positive and negative) arising from the NBN, as well as risks and opportunities that it will generate differentially between places, groups and sectors, is inherently uncertain. With little reliable data a...

  11. Local Implementation of a Broadband Network: Social Impact issues of New Broadband Capacity in Australia

    Directory of Open Access Journals (Sweden)

    Tiffany Amber Tenty

    2012-12-01

    Full Text Available In April 2009, the Australian Government announced plans to roll-out the National Broadband Network (NBN Company Open Access Network in Australia. Australia’s NBN will bring high speed internet access to areas and people that otherwise would have been without. Predicting consequences (both positive and negative arising from the NBN, as well as risks and opportunities that it will generate differentially between places, groups and sectors, is inherently uncertain. With little reliable data available on social impacts of NBN-style access at the household and community level, policy-making and regulation risks responding to optimistic speculation and commercially motivated spin rather than carefully weighed evidence. The research reported in this paper aimed to address this gap with a preliminary assessment of the social impacts of the NBN-like broadband roll-out at one New South Wales test site in southwest Sydney. The paper discusses the research methods and findings and frames recommendations for further research to address both limitations that arose in the research reported here, and broader gaps in understanding the social impacts of new forms of broadband access and associated applications. Keywords: Social Impacts, Communication Technologies, High Speed Internet

  12. Broadband fitting approach for the application of supercontinuum broadband laser absorption spectroscopy to combustion environments

    Science.gov (United States)

    Göran Blume, Niels; Ebert, Volker; Dreizler, Andreas; Wagner, Steven

    2016-01-01

    In this work, a novel broadband fitting approach for quantitative in-flame measurements using supercontinuum broadband laser absorption spectroscopy (SCLAS) is presented. The application and verification of this approach in an atmospheric, laminar, non-premixed CH4/air flame (Wolfhard-Parker burner, WHP) is discussed. The developed fitting scheme allows for an automatic recognition and fitting of a B-spline curve reference intensity for SCLAS broadband measurements while automatically removing the influence of absorption peaks. This approach improves the fitting residual locally (in between absorption lines) and globally by 23% and 13% respectively, while improving the in-flame SNR by a factor of 2. Additionally, the approach inherently improves the time-wavelength-correlation based on recorded in-flame measurements itself in combination with a theoretical spectrum of the analyte. These improvements have allowed for the recording of complete spatially resolved methane concentration profiles in the WHP burner. Comparison of the measured absolute mole fraction profile for methane with previously measured reference data shows excellent agreement in position, shape and absolute values. These improvements are a prerequisite for the application of SCLAS in high-pressure combustion systems.

  13. The Social Impact Of Broadband Household Internet Access

    OpenAIRE

    Anderson, Ben

    2008-01-01

    Broadband changes everything. Or so we are told. But does it? There is only one way to find out - follow people who move from narrowband to broadband internet access and see what changes. This paper reports exactly this kind of analysis using data from a two wave European panel study (e-Living) and the lagged endogenous regression approach to see if switching to broadband increases the time spent online, the use of online communication services, the breadth of internet activities and the amou...

  14. Ultra-broadband perfect cross polarization conversion metasurface

    Science.gov (United States)

    Dong, Guoxiang; Shi, Hongyu; Xia, Song; Zhang, Anxue; Xu, Zhuo; Wei, Xiaoyong

    2016-04-01

    We propose a metasurface with multiple plasmon resonances that achieves an ultra-broadband perfect cross polarization conversion. The metasurface is composed of an array of unit resonators, three plasmon resonances are excited in the unit resonator, which leads to an ultra-broadband perfect cross polarization conversion. The cross polarization conversion efficiency is higher than 99%, and the bandwidth of the converter is 53.7% of the central wavelength. Both numerical and experimental results were used to validate the ultra-broadband perfect cross polarization converter presented here.

  15. Statistically Based Approach to Broadband Liner Design and Assessment

    Science.gov (United States)

    Nark, Douglas M. (Inventor); Jones, Michael G. (Inventor)

    2016-01-01

    A broadband liner design optimization includes utilizing in-duct attenuation predictions with a statistical fan source model to obtain optimum impedance spectra over a number of flow conditions for one or more liner locations in a bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners having impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increasing weighting to specific frequencies and/or operating conditions. One or more broadband design approaches are utilized to produce a broadband liner that targets a full range of frequencies and operating conditions.

  16. Broadband nulling behaviour of PSR B2319+60

    CERN Document Server

    Gajjar, Vishal; Kramer, M

    2012-01-01

    Pulse nulling is one of many single pulse phenomena exhibited by radio pulsars. The broadband nature of this phenomena remained unexplained due to lack of coordinated observations. We are reporting broadband nulling behaviour of a well known nulling pulsar PSR B2319+60. The simultaneous observations were carried out at four different frequencies using the Giant Meterwave Radio telescope (325 and 610 MHz), the Westerbork Synthesis Radio Telescope (1420 MHz) and the Effelsberg radio telescope (5100 MHz). The nulling fractions were estimated at all four observed frequencies, which suggest similar degree of nulling across these frequencies. To comment on the broadband behaviour of pulse nulling, we calculated the Pearson cross-correlation coefficients for the occurrence of null and burst pulses between all four frequencies. We conclude that nulling is largely a broadband phenomenon for this pulsar and it points towards a global failure of the magnetospheric currents which produces radio emission at these frequenc...

  17. Exploiting Narrowband Efficiency for Broadband Convolutive Blind Source Separation

    Directory of Open Access Journals (Sweden)

    Aichner Robert

    2007-01-01

    Full Text Available Based on a recently presented generic broadband blind source separation (BSS algorithm for convolutive mixtures, we propose in this paper a novel algorithm combining advantages of broadband algorithms with the computational efficiency of narrowband techniques. By selective application of the Szegö theorem which relates properties of Toeplitz and circulant matrices, a new normalization is derived as a special case of the generic broadband algorithm. This results in a computationally efficient and fast converging algorithm without introducing typical narrowband problems such as the internal permutation problem or circularity effects. Moreover, a novel regularization method for the generic broadband algorithm is proposed and subsequently also derived for the proposed algorithm. Experimental results in realistic acoustic environments show improved performance of the novel algorithm compared to previous approximations.

  18. 7 CFR 1738.11 - Availability of broadband service.

    Science.gov (United States)

    2010-01-01

    ... comparable to those of similar services in neighboring urban and suburban areas, as determined by RUS; and (3..., DEPARTMENT OF AGRICULTURE RURAL BROADBAND ACCESS LOANS AND LOAN GUARANTEES Loan Purposes and Basic...

  19. Low-frequency broadband noise generated by a model rotor

    Science.gov (United States)

    Aravamudan, K. S.; Harris, W. L.

    1979-01-01

    Low-frequency broadband noise generated by model rotors is attributed to the interaction of ingested turbulence with the rotor blades. The influence of free-stream turbulence in the low-frequency broadband noise radiation from model rotors has been experimentally investigated. The turbulence was generated in the M.I.T. anechoic wind tunnel facility with the aid of bipolar grids of various sizes. The spectra and the intensity of the low-frequency broadband noise have been studied as a function of parameters which characterize the turbulence and of helicopter performance parameters. The location of the peak intensity was observed to be strongly dependent on the rotor-tip velocity and on the longitudinal integral scale of turbulence. The size scale of turbulence had negligible effect on the intensity of low-frequency broadband noise. The experimental data show good agreement with an ad hoc model based on unsteady aerodynamics.

  20. Variation of focal switch with spectrum of a broadband laser

    Science.gov (United States)

    Zhang, Biyu; Peng, Runwu; Xie, Haiqing; Zhang, Wei

    2016-05-01

    Effects of the spectrum on focal switch of a broadband laser in a dispersion dual-focus system are presented in this paper. The numerical results show that the two maximum intensities of the broadband laser on the z-axis vary when the central frequency of the broadband laser shifts and the spectrum shape changes, and the variations affect the generation of the focal switch. It is also found that difference of the two maximum intensities tends to increase when the absolute value of central wavelength increases. According to the results in this paper, the generation of the focal switch can be controlled by choosing the shift of the central frequency, the bandwidth, the distance between the two lenses, and the spectrum shape of the broadband laser.

  1. Broadband Wireless Data Acquisition and Control Device Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobitrum is proposing to develop a broadband wireless device for real-time data acquisition and monitoring applicable to the field instrumentation and control...

  2. MODERN MEASUREMENT APPROACHES OF BROADBAND WIRELESS TRANSCEIVER MODULES PARAMETERS

    OpenAIRE

    A. A. Murauyou; A. L. Khaminich

    2015-01-01

    The article contains results of development and use of non-standard methods for measuring parameters of broadband radio transceiver modules for compliance with the technical regulations of the Customs Union. 

  3. MODERN MEASUREMENT APPROACHES OF BROADBAND WIRELESS TRANSCEIVER MODULES PARAMETERS

    Directory of Open Access Journals (Sweden)

    A. A. Murauyou

    2015-08-01

    Full Text Available The article contains results of development and use of non-standard methods for measuring parameters of broadband radio transceiver modules for compliance with the technical regulations of the Customs Union. 

  4. Broadband Reflective Coating Process for Large FUVOIR Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZeCoat Corporation will develop and demonstrate a set of revolutionary coating processes for making broadband reflective coatings suitable for very large mirrors...

  5. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  6. Optimizing Broadband Terahertz Modulation with Hybrid Graphene/Metasurface Structures

    OpenAIRE

    Shi, S. -F.; Zeng, B.; Han, H. -L.; Hong, X; Tsai, H. -Z.; Jung, H. S.; Zettl, A.; Crommie, M. F.; Wang, F.

    2014-01-01

    We demonstrate efficient terahertz (THz) modulation by coupling graphene strongly with a broadband THz metasurface device. This THz metasurface, made of periodic gold slit arrays, shows near unity broadband transmission, which arises from coherent radiation of the enhanced local-field in the slits. Utilizing graphene as an active load with tunable conductivity, we can significantly modify the local-field enhancement and strongly modulate the THz wave transmission. This hybrid device also prov...

  7. Mediating effects of broadband consumers’ behavior in India

    OpenAIRE

    G, Thiagarajan; Nakkeeran, Senthilkumar; Arockiasamy, Arulraj

    2010-01-01

    Internet usage is rapidly growing in areas like cosmopolitan cities, semi-urban cities in India. I-enabled services offered by various government agencies, educational institutions and commercial activities force users of these services to seek superior internet access like broadband, WiMax is likely to replace traditional broadband and dial-up access soon. Interestingly, reforms in telecom sector are taking place at a rapid pace in India. Many private players started internet services affect...

  8. Drivers of fixed and mobile broadband infrastructure adoption and quality

    OpenAIRE

    Tsai, Hsin-yi Sandy; Bauer, Johannes M.

    2014-01-01

    The benefits of advanced information and communication services are increasingly dependent on the quality of the available connectivity. This paper examines the factors that influence the quality of fixed and mobile broadband access in OECD countries. Drawing on institutional economics, the study provides an integrated conceptual framework that allows analyzing the interaction of supply, demand, policy, and contextual factors. We explore the drivers of broadband access and quality and potenti...

  9. Efficiency of broadband internet adoption in European Union member states

    OpenAIRE

    Pavlyuk, Dmitry

    2011-01-01

    This paper is devoted to econometric analysis of broadband adoption efficiency in EU member states. Stochastic frontier models are widely used for efficiency estimation. We enhanced the stochastic frontier model by adding a spatial component into the model specification to reflect possible dependencies between neighbour countries. A maximum likelihood estimator for the model was developed. The proposed spatial autoregressive stochastic frontier model is used for estimation of broadband ad...

  10. Assessment of wireless solutions in emerging broadband markets

    OpenAIRE

    Benseny Quintana, Jaume

    2016-01-01

    Although broadband markets have grown steadily since the advent of the mobile Internet, penetration levels for developing countries are far from reaching the ordinary citizen. This thesis analyses three hypotheses as bottlenecks to the growth of emerging mobile broadband markets: (i) the low competence of users, (ii) the low quality of service, (iii) the high access price and, based on the results, alternative wireless solutions are studied to accelerate the Internet diffusion. Bottleneck...

  11. Novel crystalline-waveguide broadband light sources for interferometry

    OpenAIRE

    Pollnau, Markus

    2003-01-01

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The longitudinal resolution of such instruments is inversely proportional to the optical bandwidth of the light source. Broadband luminescence from transition-metal-ion doped materials can significantly improve t...

  12. Competition, Regulation, and Broadband Access to the Internet

    OpenAIRE

    Götz, Georg

    2009-01-01

    This paper re-examines the effect of the regulatory regime on both penetration and coverage of broadband access to the internet. The framework also allows for an evaluation of different public policy measures such as subsidization of broadband demand and supply. A welfare analysis asks what the optimal regulatory regime is and whether and how high-speed access to the internet should be subsidized. Using an approach similar to Valletti et al. (2002), the paper highlights the importance of popu...

  13. Deployment and operational aspects of rural broadband wireless access networks

    OpenAIRE

    Bernardi, Giacomo

    2012-01-01

    Broadband speeds, Internet literacy and digital technologies have been steadily evolving over the last decade. Broadband infrastructure has become a key asset in today’s society, enabling innovation, driving economic efficiency and stimulating cultural inclusion. However, populations living in remote and rural communities are unable to take advantage of these trends. Globally, a significant part of the world population is still deprived of basic access to the Internet. Broad...

  14. A Performance Study of Wireless Broadband Access (WiMAX)

    OpenAIRE

    Maan A. S. Al-Adwany

    2011-01-01

    WiMAX (worldwide interoperability for microwave access) is one of the wireless broadband access technologies which supplies broadband services to clients, but it surpasses other technologies by its coverage area, where one base station can cover a small city. In this paper, WiMAX technology is studied by exploring its basic concepts, applications, and advantages / disadvantages. Also a MATLAB simulator is used to verify the operation of the WiMAX system under various chan...

  15. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    CERN Document Server

    Staude, Isabelle; Decker, Manuel; Miroshnichenko, Andrey E; Neshev, Dragomir N; Jagadish, Chennupati; Kivshar, Yuri S

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly reflecting their broadband characteristics.

  16. Broadband metasurface absorber for solar thermal applications

    Science.gov (United States)

    Wan, C.; Chen, L.; Cryan, M. J.

    2015-12-01

    In this paper we propose a broadband polarization-independent selective absorber for solar thermal applications. It is based on a metal-dielectric-metal metasurface structure, but with an interlayer of absorbing amorphous carbon rather than a low loss dielectric. Optical absorbance results derived from finite difference time domain modelling are shown for ultra-thin carbon layers in air and on 200 nm of gold for a range of carbon thicknesses. A gold-amorphous carbon-gold trilayer with a top layer consisting of a 1D grating is then optimised in 2D to give a sharp transition from strong absorption up to 2 μm to strong reflection above 2 μm resulting in good solar selective performance. The gold was replaced by the high-melting-point metal tungsten, which is shown to have very similar performance to the gold case. 3D simulations then show that the gold-based structure performs well as a square periodic array of squares, however there is low absorption around 400 nm. A cross-based structure is found to increase this absorption without significantly reducing the performance at longer wavelengths.

  17. Broadband Observations of High Redshift Blazars

    CERN Document Server

    Paliya, Vaidehi S; Fabian, A C; Stalin, C S

    2016-01-01

    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 ($z=3.37$), CGRaBS J0225+1846 ($z=2.69$), BZQ J1430+4205 ($z=4.72$), and 3FGL J1656.2$-$3303 ($z=2.40$), using the quasi-simultaneous data from {\\it Swift}, {\\it NuSTAR}, and {\\it Fermi}-Large Area Telescope (LAT) and also the archival {\\it XMM-Newton} observations. Other than 3FGL J1656.2$-$3303, none of the sources were known as $\\gamma$-ray emitters and our analysis of $\\sim$7.5 years of LAT data reveals the first time detection of the statistically significant $\\gamma$-ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of {\\it NuSTAR} observations and reproduce them using a one zone leptonic emission model. The optical$-$UV emission in all the objects can be explained by the radiation from the accretion disk, whereas, X-ray to $\\gamma$-ray window of the SEDs are found to be dominated by the inverse Compton scattering off the broad line reg...

  18. Impedance matching for broadband piezoelectric energy harvesting

    International Nuclear Information System (INIS)

    This paper presents a system design for broadband piezoelectric energy harvesting by means of impedance matching. An inductive load impedance is emulated by controlling the output current of the piezoelectric harvester with a bipolar boost converter. The reference current is derived from the low pass filtered voltage measured at the harvester terminals. In order to maximize the harvested power especially for nonresonant frequencies the filter parameters are adjusted by a simple optimization algorithm. However the amount of harvested power is limited by the efficiency of the bipolar boost converter. Therefore an additional switch in the bipolar boost converter is proposed to reduce the capacitive switching losses. The proposed system is simulated using numerical parameters of available discrete components. Using the additional switch, the harvested power is increased by 20%. The proposed system constantly harvests 80% of the theoretically available power over frequency. The usable frequency range of ±4Hz around the resonance frequency of the piezoelectric harvester is mainly limited due to the boost converter topology. This comparison does not include the power dissipation of the control circuit

  19. The Broadband Afterglow of GRB980703

    CERN Document Server

    Frail, D A; Berger, E; Harrison, F A; Sari, R; Kulkarni, S R; Taylor, G B; Bloom, J S; Fox, D W; Moriarty-Schieven, G H; Price, P A

    2003-01-01

    We present radio observations of the afterglow of the bright gamma-ray burst GRB980703 made between one day and one year after the burst. These data are combined with published late-time radio measurements and existing optical, near-infrared (NIR) and X-ray observations to create a comprehensive broadband dataset for modeling the physical parameters of the outflow. While a wind-stratified medium cannot be ruled out statistically, it requires a high fraction of the shock energy in the electrons, and so is not favored on theoretical grounds. Instead, the data are consistent with a fireball model in which the ejecta are collimated and expanding into a constant density medium. The radio data cannot be fit with an isotropic shock but instead require a jet break at ~ 3.5 days, not seen at optical wavelengths due to the presence of a a bright host galaxy. The addition of the full radio dataset constrains the self-absorption frequency, giving an estimate of the circumburst density of n ~ 30 cm^-3, a value which diffe...

  20. Investigating broadband acoustic adsorption using rapid manufacturing

    Science.gov (United States)

    Godbold, O.

    The reduction of nuisance noise and the removal of unwanted sound modes within a room or component enclosure-area can be accomplished through the use of acoustic absorbers. Sound absorption can be achieved through conversion of the kinetic energy associated with pressure waves, into heat energy via viscous dissipation. This occurs within open porous materials, or by utilising resonant effects produced using simple cavity and orifice configurations. The manufacture of traditional porous and resonant absorbers is commonly realised using basic manufacturing techniques. These techniques restrict the geometry of a given resonant construction, and limit the configuration of porous absorbers. The aim of this work is to exploit new and emerging capabilities of Rapid Manufacturing (RM) to produce components with geometrical freedom, and apply it to the development of broadband acoustic absorption. New and novel absorber geometric configurations are identified and their absorption performance is determined. The capabilities and limitations of RM processes in reproducing these configurations are demonstrated. The geometric configuration of RM resonant absorbers is investigated. Cavity modifications aimed at damping the resonant effect by restricting the motion of cavity air, and adding increased viscous resistance are explored. Modifications relating to cavity shape, the addition of internal perforations and increased cavity surface area have all been shown to add acoustic resistance, thereby increasing the bandwidth of absorption. Decreasing the hydraulic radius of the cavity cross section and reducing internal feature dimensions provide improved resistance over conventional configurations..

  1. Highly coherent modeless broadband semiconductor laser.

    Science.gov (United States)

    Sellahi, M; Myara, M; Beaudoin, G; Sagnes, I; Garnache, A

    2015-09-15

    We report on the highly coherent modeless broadband continuous wave operation of a semiconductor vertical-external-cavity-surface-emitting laser. The laser design is based on a frequency-shifted-feedback scheme provided by an acousto-optic frequency shifter inserted in a linear or a ring traveling wave cavity. The gain mirror is a GaAs-based multiple quantum well structure providing large gain at 1.07 μm. This laser exhibits a coherent optical spectrum over 1.27 nm (330 GHz) bandwidth, with 70 mW output power and a high beam quality. The light polarization is linear (>30  dB extinction ratio). The laser dynamics exhibits a low intensity noise close to class A regime, with a ∼1.5  MHz cutoff frequency. The frequency noise spectral density shows a first-order low-pass like shape (130 kHz cutoff) leading to a Gaussian shape for homodyne interferometric signals. The measured beat width is ≃54  kHz and the coherence time of ∼19  μs. No nonlinear effects are observed, showing dynamics very close to theory. PMID:26371921

  2. Broadband Spectral Analysis of Aql X-1

    CERN Document Server

    Raichur, H; Dewangan, G

    2011-01-01

    We present the results of a broadband spectral study of the transient Low Mass X-ray Binary Aql X-1 observed by Suzaku and Rossi X-ray Timing Explorer satellites. The source was observed during its 2007 outburst in the High/Soft (Banana) state and in the Low/Hard (Extreme Island) state. Both the Banana state and the Extreme Island state spectra are best described by a two component model consisting of a soft multi-colour blackbody emission likely originating from the accretion disk and a harder Comptonized emission from the boundary layer. Evidence for a hard tail (extending to ~50 keV) is found during the Banana state; this further (transient) component, accounting for atleast ~1.5% of the source luminosity, is modeled by a power-law. Aql X-1 is the second Atoll source after GX 13+1 to show a high energy tail. The presence of a weak but broad Fe line provides further support for a standard accretion disk extending nearly to the neutron star surface. The input photons for the Comptonizing boundary layer could...

  3. Broadband Linear Polarization of Jupiter Trojans

    CERN Document Server

    Bagnulo, S; Stinson, A; Christou, A; Borisov, G B

    2016-01-01

    Trojan asteroids orbit in the Lagrange points of the system Sun-planet-asteroid. Their dynamical stability make their physical properties important proxies for the early evolution of our solar system. To study their origin, we want to characterize the surfaces of Jupiter Trojan asteroids and check possible similarities with objects of the main belt and of the Kuiper Belt. We have obtained high-accuracy broad-band linear polarization measurements of six Jupiter Trojans of the L4 population and tried to estimate the main features of their polarimetric behaviour. We have compared the polarimetric properties of our targets among themselves, and with those of other atmosphere-less bodies of our solar system. Our sample show approximately homogeneous polarimetric behaviour, although some distinct features are found between them. In general, the polarimetric properties of Trojan asteroids are similar to those of D- and P-type main-belt asteroids. No sign of coma activity is detected in any of the observed objects. A...

  4. Broadband Acoustic Cloak for Ultrasound Waves

    CERN Document Server

    Zhang, Shu; Fang, Nicholas

    2010-01-01

    Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (~6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of ma...

  5. Hollow plasmonic antennas for broadband SERS spectroscopy

    Directory of Open Access Journals (Sweden)

    Gabriele C. Messina

    2015-02-01

    Full Text Available The chemical environment of cells is an extremely complex and multifaceted system that includes many types of proteins, lipids, nucleic acids and various other components. With the final aim of studying these components in detail, we have developed multiband plasmonic antennas, which are suitable for highly sensitive surface enhanced Raman spectroscopy (SERS and are activated by a wide range of excitation wavelengths. The three-dimensional hollow nanoantennas were produced on an optical resist by a secondary electron lithography approach, generated by fast ion-beam milling on the polymer and then covered with silver in order to obtain plasmonic functionalities. The optical properties of these structures have been studied through finite element analysis simulations that demonstrated the presence of broadband absorption and multiband enhancement due to the unusual geometry of the antennas. The enhancement was confirmed by SERS measurements, which showed a large enhancement of the vibrational features both in the case of resonant excitation and out-of-resonance excitation. Such characteristics indicate that these structures are potential candidates for plasmonic enhancers in multifunctional opto-electronic biosensors.

  6. Broadband Infrared Heterodyne Spectrometer: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C G; Cunningham, C T; Tringe, J W

    2010-12-16

    This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.

  7. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua; Li, Chuanrong; Li, Zhao-Liang

    2011-01-01

    This work analyzed and addressed the estimate of the broadband emissivities for the spectral domains 3-14μm (ε(3-14)) and 3-∞μm (ε(3-∞). Two linear narrow-to-broadband conversion models were proposed to estimate broadband emissivities ε(3-14) and ε(3-∞) using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived emissivities in three thermal infrared channels 29 (8.4-8.7μm), 31 (10.78-11.28μm) and 32 (11.77-12.27μm). Two independent spectral libraries, the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library and the MODIS UCSB (University of California, Santa Barbara) emissivity library, were used to calibrate and validate the proposed models. Comparisons of the estimated broadband emissivities using the proposed models and the calculated values from the spectral libraries, showed that the proposed method of estimation of broadband emissivity has potential accuracy and the Root Mean Square Error (RMSE) between estimated and calculated broadband emissivities is less than 0.01 for both ε(3-14) and ε(3-∞). PMID:21263556

  8. Broadband magnetotellurics over the Swedish Caledonides

    Science.gov (United States)

    Garcia Juanatey, M. A.; Juhlin, C.; Ping, Y.

    2013-12-01

    In connection with the drilling project Collisional Orogeny in the Scandinavian Caledonides (COSC), broadband magnetotelluric (MT) data were acquired along a 60 km long transect in central Sweden. The COSC project, with drilling costs funded by the International Continental Scientific Program (ICDP) and the Swedish Research Council (VR), focuses on the study of mountain building processes through the investigation of the composition and structure of the Caledonides. The project encompasses two fully cored boreholes to ~2.5 km depth. The plan is to locate the boreholes so they penetrate structures at different levels of the tectonostratigraphy of the mountain belt. Before acquisition of the current MT data, several seismic reflection surveys were carried out to determine the location of the first borehole (COSC-1). The objectives of the MT measurements are to provide more information about the deeper structures, and complement the seismic reflection studies carried out along the same profile. In total, 86 MT soundings were recorded, three different sampling modes were used: 3000 Hz for half an hour in daytime, 1000 Hz for two hours around midnight and 20 Hz for ˜24 hours continuously. All stations recorded two horizontal components of the electric and magnetic fields, and about 40% of them, distributed along the whole profile, recorded also the vertical component of the magnetic field. The station spacing was 600 m close to possible drill sites and where there are gaps in the seismic data. Otherwise the spacing is of the order of 1 km. Data quality varies from very good to noisy nearby urban areas. Results from these data set will be combined with other geophysical methods to improve the 3D geological model of the area around the COSC-1 drill site. Additionally, it is expected that this data set will help to determine the location of the second borehole, COSC-2.

  9. Computing broadband accelerograms using kinematic rupture modeling

    International Nuclear Information System (INIS)

    In order to make the broadband kinematic rupture modeling more realistic with respect to dynamic modeling, physical constraints are added to the rupture parameters. To improve the slip velocity function (SVF) modeling, an evolution of the k-2 source model is proposed, which consists to decompose the slip as a sum of sub-events by band of k. This model yields to SVF close to the solution proposed by Kostrov for a crack, while preserving the spectral characteristics of the radiated wave field, i.e. a w2 model with spectral amplitudes at high frequency scaled to the coefficient of directivity Cd. To better control the directivity effects, a composite source description is combined with a scaling law defining the extent of the nucleation area for each sub-event. The resulting model allows to reduce the apparent coefficient of directivity to a fraction of Cd, as well as to reproduce the standard deviation of the new empirical attenuation relationships proposed for Japan. To make source models more realistic, a variable rupture velocity in agreement with the physics of the rupture must be considered. The followed approach that is based on an analytical relation between the fracture energy, the slip and the rupture velocity, leads to higher values of the peak ground acceleration in the vicinity of the fault. Finally, to better account for the interaction of the wave field with the geological medium, a semi-empirical methodology is developed combining a composite source model with empirical Green functions, and is applied to the Yamaguchi, Mw 5.9 earthquake. The modeled synthetics reproduce satisfactorily well the observed main characteristics of ground motions. (author)

  10. The Representation of a Broadband Vector Field

    Institute of Scientific and Technical Information of China (English)

    Qunyan Ren; Jean Pierre Hermand; Shengchun Piao

    2011-01-01

    Compared to a scalar pressure sensor,a vector sensor can provide a higher signal-to-noise ratio (SNR)signal and more detailed information on the sound field.Study on vector sensors and their applications have become a hot topic.Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology.This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship,and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform.From theory analysis and numerical simulation,the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but,being quantitatively different,provides additional information on the waveguide,especially through the vertical component.For the range-frequency representation,physical quantities that can better exhibit the interference characteristics of the waveguide are the products of pressure and particle velocity and of the pressure and pressure gradient.An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly.The representation of the vector impulse response was discussed according to two different measurement systems,also known as particle velocity and pressure gradient.The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.

  11. Broadband set-top box using MAP-CA processor

    Science.gov (United States)

    Bush, John E.; Lee, Woobin; Basoglu, Chris

    2001-12-01

    Advances in broadband access are expected to exert a profound impact in our everyday life. It will be the key to the digital convergence of communication, computer and consumer equipment. A common thread that facilitates this convergence comprises digital media and Internet. To address this market, Equator Technologies, Inc., is developing the Dolphin broadband set-top box reference platform using its MAP-CA Broadband Signal ProcessorT chip. The Dolphin reference platform is a universal media platform for display and presentation of digital contents on end-user entertainment systems. The objective of the Dolphin reference platform is to provide a complete set-top box system based on the MAP-CA processor. It includes all the necessary hardware and software components for the emerging broadcast and the broadband digital media market based on IP protocols. Such reference design requires a broadband Internet access and high-performance digital signal processing. By using the MAP-CA processor, the Dolphin reference platform is completely programmable, allowing various codecs to be implemented in software, such as MPEG-2, MPEG-4, H.263 and proprietary codecs. The software implementation also enables field upgrades to keep pace with evolving technology and industry demands.

  12. Negative impedance shunted electromagnetic absorber for broadband absorbing: experimental investigation

    International Nuclear Information System (INIS)

    The traditional tuned mass absorber is widely employed to control the vibration of a primary structure by transferring the vibrating energy to the absorber. However, the working band of the absorber is very narrow, which limits the application of broadband vibration control. This study presents a novel broadband electromagnetic absorber by first introducing two negative impedance shunts to improve broadband damping of the absorber. The electromagnetic absorber is modeled, and the corresponding electromagnetic coupling coefficient is tested. A cantilever beam is employed to verify the broadband vibration absorption of the negative resistance (NR) shunted electromagnetic absorber (NR absorber) and the negative inductance NR shunted electromagnetic absorber (NINR absorber). The governing equations of the beam with two absorbers are derived, and the experiments are set up. The results point out that the NR and NINR absorbers can attenuate the broadband vibration. The proposed absorbers do not need the feedback system and the real-time controller compared to the active absorber; hence, they have great application potential in aerospace and in submarine applications, as well as in civil and mechanical engineering. (paper)

  13. Broadband Access Network Planning Optimization Considering Real Copper Cable Lengths

    Science.gov (United States)

    Peternel, Blaž Kos, Andrej

    Broadband access network planning strategies with techno-economic calculations are important topics, when optimal broadband network deployments are considered. This paper analyzes optimal deployment combination of digital subscriber line technologies (xDSL) and fiber to the home technologies (FTTx), following different user bandwidth demand scenarios. For this reason, optimal placement of remote digital subscriber line multiplexer (RDSLAM) is examined. Furthermore, the article also discusses the economy of investments, depending on certain investment threshold and the reach of different xDSL technologies. Finally, the difference between broadband network deployment in a characteristic urban and rural area in Republic of Slovenia, in terms of required optical cable dig length per household is shown. A tree structure network model of a traditional copper access network is introduced. A dynamic programming logic, with recursion as a basis of a tree structure examination and evaluation of optimal network elements placement is used. The tree structure network model considers several real network parameters (e. g.: copper cable lengths, user coordinates, node coordinates). The main input for the optimization is a local loop distance between each user and a candidate node for RDSLAM placement. Modelling of copper access networks with a tree structure makes new extensions in planning optimization of broadband access networks. Optimization of network elements placement has direct influence on efficiency and profitability of broadband access telecommunication networks.

  14. Broadband Observations of High Redshift Blazars

    Science.gov (United States)

    Paliya, Vaidehi S.; Parker, M. L.; Fabian, A. C.; Stalin, C. S.

    2016-07-01

    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2‑3303 (z = 2.40) using quasi-simultaneous data from the Swift, Nuclear Spectroscopic Telescope Array (NuSTAR) and the Fermi-Large Area Telescope (LAT) and also archival XMM-Newton observations. Other than 3FGL J1656.2‑3303, none of the sources were known as γ-ray emitters, and our analysis of ∼7.5 yr of LAT data reveals the first time detection of statistically significant γ-ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of NuSTAR observations and reproduce them using a one-zone leptonic emission model. The optical‑UV emission in all the objects can be explained by radiation from the accretion disk, whereas the X-ray to γ-ray windows of the SEDs are found to be dominated by inverse Compton scattering off the broad line region photons. All of them host black holes that are billions of solar masses. Comparing the accretion disk luminosity and the jet power of these sources with a large sample of blazars, we find them to occupy a high disk luminosity–jet power regime. We also investigate the X-ray spectral properties of the sources in detail with a major focus on studying the causes of soft X-ray deficit, a feature generally seen in high redshift radio-loud quasars. We summarize that this feature could be explained based on the intrinsic curvature in the jet emission rather than being due to the external effects predicted in earlier studies, such as host galaxy and/or warm absorption.

  15. Inferring surface solar absorption from broadband satellite measurements

    Science.gov (United States)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    An atmospheric solar radiation model and surface albedo models that include wavelength dependence and surface anisotropy are combined to study the possibility of inferring the surface solar absorption from satellite measurements. The model includes ocean, desert, pasture land, savannah, and bog surface categories. Problems associated with converting narrowband measurements to broadband quantities are discussed, suggesting that it would be easier to infer surface solar absorption from broadband measurements directly. The practice of adopting a linear relationship between planetary and surface albedo to estimate surface albedos from satellite measurements is examined, showing that the linear conversion between broadband planetary and surface albedos is strongly dependent on vegetation type. It is suggested that there is a linear slope-offset relationship between surface and surface-atmosphere solar absorption.

  16. Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Jerome K. [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun, E-mail: hyeounkim@nnfc.re.kr, E-mail: jhpark@nnfc.re.kr; Park, Jae Hong, E-mail: hyeounkim@nnfc.re.kr, E-mail: jhpark@nnfc.re.kr [National Nano-Fab Center, Daejeon 305-701 (Korea, Republic of); Lee, Won-Oh [S-Package Solution Co., Ltd., Daegu 702-701 (Korea, Republic of)

    2015-12-21

    High performance microbolometers are widely sought for thermal imaging applications. In order to increase the performance limits of microbolometers, the responsivity of the device to broadband infrared (IR) radiation needs to be improved. In this work, we report a simple, quick, and cost-effective approach to modestly enhance the broadband IR response of the device by evaporating Ag nanocrystals onto the light entrance surface of the device. When irradiated with IR light, strong fields are built up within the gaps between adjacent Ag nanocrystals. These fields resistively generate heat in the nanocrystals and underlying substrate, which is transduced into an electrical signal via a resistive sensing element in the device. Through this method, we are able to enhance the IR absorption over a broadband spectrum and improve the responsivity of the device by ∼11%.

  17. Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

    International Nuclear Information System (INIS)

    High performance microbolometers are widely sought for thermal imaging applications. In order to increase the performance limits of microbolometers, the responsivity of the device to broadband infrared (IR) radiation needs to be improved. In this work, we report a simple, quick, and cost-effective approach to modestly enhance the broadband IR response of the device by evaporating Ag nanocrystals onto the light entrance surface of the device. When irradiated with IR light, strong fields are built up within the gaps between adjacent Ag nanocrystals. These fields resistively generate heat in the nanocrystals and underlying substrate, which is transduced into an electrical signal via a resistive sensing element in the device. Through this method, we are able to enhance the IR absorption over a broadband spectrum and improve the responsivity of the device by ∼11%

  18. Photo-excited broadband tunable terahertz metamaterial absorber

    Science.gov (United States)

    Zhang, Jianna; Wang, Guocui; Zhang, Bo; He, Ting; He, Yanan; Shen, Jingling

    2016-04-01

    We demonstrate a photo-excited broadband tunable metamaterial absorber for use in the terahertz region. The metamaterial absorber consists of a hybrid metal-semiconductor square split ring and a metallic ground plane that are separated by a dielectric resonator spacer. The conductivity of the silicon used to fill the gap in the metallic resonator is tuned actively as a function of the incident pump power, which results in frequency modulation of the resonance absorption peak. Broadband tunable metamaterial absorbers are produced by suitable placement of the photoconductive silicon in different critical regions of the metallic resonator. In addition, the proposed method is applicable to a concentric rings-based metallic resonator. The proposed photo-excited broadband tunable metamaterial absorber has numerous potential applications, including uses as terahertz modulators and switches.

  19. Piezomagnetoelastic broadband energy harvester: Nonlinear modeling and characterization

    Science.gov (United States)

    Aravind Kumar, K.; Ali, S. F.; Arockiarajan, A.

    2015-11-01

    Piezomagnetoelastic energy harvesters are one among the widely explored configurations to improve the broadband characteristics of vibration energy harvesters. Such nonlinear harvesters follow a Moon beam model with two magnets at the base and one at the tip of the beam. The present article develops a geometric nonlinear mathematical model for the broadband piezomagnetoelastic energy harvester. The electromechanical coupling and the nonlinear magnetic potential equations are developed from the dimensional system parameters to describe the nonlinear dynamics exhibited by the system. The developed model is capable of characterizing the monostable, bistable and tristable operating regimes of the piezomagnetoelastic energy harvester, which are not explicit in the Duffing representation of the system. Bifurcations and attractor motions are analyzed as nonlinear functions of the distance between base magnets and the field strength of the tip magnet. The model is further used to characterize the potential wells and stable states, with due focus on the performance of the system in broadband energy harvesting.

  20. Light source for narrow and broadband coherent Raman scattering microspectroscopy.

    Science.gov (United States)

    Brinkmann, Maximilian; Dobner, Sven; Fallnich, Carsten

    2015-12-01

    We present a light source that is well adapted to both narrow- and broadband coherent Raman scattering (CRS) methods. Based on a single oscillator, the light source delivers synchronized broadband pulses via supercontinuum generation and narrowband, frequency-tunable pulses via four-wave mixing in a photonic crystal fiber. Seeding the four-wave mixing with a spectrally filtered part of the supercontinuum yields high-pulse energies up to 8 nJ and the possibility of scanning a bandwidth of 2000  cm(-1) in 25 ms. All pulses are emitted with a repetition frequency of 1 MHz, which ensures efficient generation of CRS signals while avoiding significant damage of the samples. Consequently, the light source combines the performance of individual narrow- and broadband CRS light sources in one setup, thus enabling hyperspectral imaging and rapid single-resonance imaging in parallel. PMID:26625022

  1. Swift/BAT and MAXI/GSC Broadband Transient Monitor

    CERN Document Server

    Sakamoto, Takanori; Mihara, Tatehiro; Yoshida, Atsumasa; Arimoto, Makoto; Barthelmy, Scott D; Kawai, Nobuyuki; Krimm, Hans A; Nakahira, Satoshi; Serino, Motoko

    2015-01-01

    We present the newly developed broadband transient monitor using the Swift Burst Alert Telescope (BAT) and the MAXI Gas Slit Camera (GSC) data. Our broadband transient monitor monitors high energy transient sources from 2 keV to 200 keV in seven energy bands by combining the BAT (15-200 keV) and the GSC (2-20 keV) data. Currently, the daily and the 90-minute (one orbit) averaged light curves are available for 106 high energy transient sources. Our broadband transient monitor is available to the public through our web server, http://yoshidalab.mydns.jp/bat_gsc_trans_mon/, for a wider use by the community. We discuss the daily sensitivity of our monitor and possible future improvements to our pipeline.

  2. High-sensitivity broadband microwave spectroscopy with small nonresonant coils

    Science.gov (United States)

    Mahdjour, H.; Clark, W. G.; Baberschke, K.

    1986-06-01

    The use of a small, nonresonant, coil of micron dimensions as the microwave magnetic field structure of a broadband electron-spin-resonance (ESR) spectrometer is described. The coil is driven by a broadband microwave generator which operates between 0.1 and 8.5 GHz. The samples may fill the coil to approximately 100 percent. It is shown that for small size samples this system offers higher sensitivity than a conventional cavity spectrometer. Because the system is broadband, either frequency scans or the conventional magnetic field scans can be used to traverse the resonance. Examples for DPPH and for the spin glass AgMn using this method are reported. Since the sample coil is small, it has many potential applications, such as insertion into the mixing chamber of dilution refrigerator or high-pressure cell, efficient use of power in ENDOR and other double resonance experiments, and rapid recovery from transients in pulsed ESR experiments.

  3. Symmetry-Breaking Plasmonic Metasurfaces for Broadband Light Bending

    DEFF Research Database (Denmark)

    Ni, Xingjie; Emani, Naresh K.; Kildishev, Alexander V.;

    2012-01-01

    We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface.......We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface....

  4. Optimizing broadband terahertz modulation with hybrid graphene/metasurface structures.

    Science.gov (United States)

    Shi, S-F; Zeng, B; Han, H-L; Hong, X; Tsai, H-Z; Jung, H S; Zettl, A; Crommie, M F; Wang, F

    2015-01-14

    We demonstrate efficient terahertz (THz) modulation by coupling graphene strongly with a broadband THz metasurface device. This THz metasurface, made of periodic gold slit arrays, shows near unity broadband transmission, which arises from coherent radiation of the enhanced local-field in the slits. Utilizing graphene as an active load with tunable conductivity, we can significantly modify the local-field enhancement and strongly modulate the THz wave transmission. This hybrid device also provides a new platform for future nonlinear THz spectroscopy study of graphene. PMID:25483819

  5. Synchrony in broadband fluctuation and the 2008 financial crisis.

    Directory of Open Access Journals (Sweden)

    Der Chyan Lin

    Full Text Available We propose phase-like characteristics in scale-free broadband processes and consider fluctuation synchrony based on the temporal signature of significant amplitude fluctuation. Using wavelet transform, successful captures of similar fluctuation pattern between such broadband processes are demonstrated. The application to the financial data leading to the 2008 financial crisis reveals the transition towards a qualitatively different dynamical regime with many equity price in fluctuation synchrony. Further analysis suggests an underlying scale free "price fluctuation network" with large clustering coefficient.

  6. Broadband polymer microstructured THz fiber coupler with downdoped cores

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole; Jepsen, Peter Uhd

    2010-01-01

    We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz.......We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz....

  7. Sensitive, time-resolved, broadband spectroscopy of single transient processes

    Science.gov (United States)

    Fjodorow, Peter; Baev, Ivan; Hellmig, Ortwin; Sengstock, Klaus; Baev, Valery M.

    2015-09-01

    Intracavity absorption spectroscopy with a broadband Er3+-doped fiber laser is applied to time-resolved measurements of transient gain and absorption in electrically excited Xe and Kr plasmas. The achieved time resolution for broadband spectral recording of a single process is 25 µs. For pulsed-periodic processes, the time resolution is limited by the laser pulse duration, which is set here to 3 µs. This pulse duration also predefines the effective absorption path length, which amounts to 900 m. The presented technique can be applied to multicomponent analysis of single transient processes such as shock tube experiments, pulse detonation engines, or explosives.

  8. Broadband development in the Czech and Slovak Republics

    Czech Academy of Sciences Publication Activity Database

    Kuchar, Anton; Hrstka, J.; Murín, V.

    Vol. E8. Geneve : BReATH Consortium, 2006, --. [BReATH Closing Conference. Geneve (CH), 11.12.2006] Grant ostatní: BReATH Consortium EU(XE) EC FP6 1ST Programme Institutional research plan: CEZ:AV0Z20670512 Keywords : Internet * telecommunication networks * broadband networks Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.ist-breath.net/documents/BReATH/E8_Closing_Conference/presentations/session_II/Kuchar_-_Broadband_development_in_CZ_and_SR.pdf

  9. Bragg-Berry mirrors: reflective broadband q-plates

    CERN Document Server

    Rafayelyan, Mushegh

    2016-01-01

    We report on the experimental realization of flat mirrors enabling the broadband generation of optical vortices upon reflection. The effect is based on the geometric Berry phase associated with the circular Bragg reflection phenomenon from chiral uniaxial media. We show the reflective optical vortex generation from both diffractive and nondiffractive paraxial light beams using spatially patterned chiral liquid crystal films. The intrinsic spectrally broadband character of spin-orbit generation of optical phase singularities is demonstrated over the full visible domain. Our results do not rely on any birefringent retardation requirement and consequently foster the development of a novel generation of robust optical elements for spin-orbit photonic technologies.

  10. Upper Bound Performance Estimation for Copper Based Broadband Access

    DEFF Research Database (Denmark)

    Jensen, Michael; Gutierrez Lopez, Jose Manuel

    2012-01-01

    Around 70% of all broadband connections in the European Union are carried over copper, and the scenario is unlikely to change in the next few years as carriers still believe in the profitability of their copper infrastructure. In this paper we show how to estimate the performance upper bound of...... define the limitations of copper based broadband access. A case study in a municipality in Denmark shows how the estimated network dimension to be able to provide video conference services to the majority of the population might be too high to be implemented in reality....

  11. Experimental demonstration of quantum teleportation of broadband squeezing.

    Science.gov (United States)

    Yonezawa, Hidehiro; Braunstein, Samuel L; Furusawa, Akira

    2007-09-14

    We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe -0.8+/-0.2 dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of broadband entanglement. Our teleporter achieves sufficiently high fidelity to allow the teleportation to be cascaded, enabling, in principle, the construction of deterministic non-Gaussian operations. PMID:17930422

  12. A novel structure for a broadband left-handed metamaterial

    International Nuclear Information System (INIS)

    A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross (MSMC) structure is proposed and investigated numerically and experimentally in the microwave frequency range. The effective media parameters were retrieved from the numerical and experimental results, which clearly show that there exists a very wide frequency band where the permittivity and permeability are negative. The influence of the structure parameters on the magnetic response and the cut-off frequency of the negative permittivity are studied in detail. This metamaterial would have potential application in designing broadband microwave devices

  13. The Quest for Ultimate Broadband High Power Microwaves

    CERN Document Server

    Podgorski, Andrew S

    2014-01-01

    Paper describes High Power Microwave research of combining GW peak power to achieve MV/m and GV/m radiated fields in 1 to 500 GHz band. To achieve such fields multiple independently triggered broadband GW sources, supplying power to multiple spatially distributed broadband radiators/antennas are used. Single TW array is used as an ultimate microwave weapon in 1 to 5 GHz range while multiple TW arrays provide GV/m radiating field at plasma frequencies in 300 GHz range leading to fusion power.

  14. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.;

    1997-01-01

    Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity of...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....

  15. Implementation of Scientific Computing Applications on the Cell Broadband Engine

    Directory of Open Access Journals (Sweden)

    Guochun Shi

    2009-01-01

    Full Text Available The Cell Broadband Engine architecture is a revolutionary processor architecture well suited for many scientific codes. This paper reports on an effort to implement several traditional high-performance scientific computing applications on the Cell Broadband Engine processor, including molecular dynamics, quantum chromodynamics and quantum chemistry codes. The paper discusses data and code restructuring strategies necessary to adapt the applications to the intrinsic properties of the Cell processor and demonstrates performance improvements achieved on the Cell architecture. It concludes with the lessons learned and provides practical recommendations on optimization techniques that are believed to be most appropriate.

  16. Analysis of broadband aerodynamic noise from VS45

    Energy Technology Data Exchange (ETDEWEB)

    Dundabin, P. [Renewable Energy Systems Ltd., Glasgow, Scotland (United Kingdom)

    1997-12-31

    This paper describes the analysis of acoustic data taken from the VS45 at Kaiser-Wilhelm-Koog. The aim was to investigate the dependence of aerodynamic noise on tip speed and angle of attack. In particular, the dependence of noise in individual third octave bands on these variable is examined. The analysis is divided into 3 sections: data selection, data checks and analysis of broadband nacelle noise; analysis of broadband aerodynamic noise and its sensitivity to tip speed and angle of attack. (LN)

  17. Investigations for broadband internet within high-speed trains

    OpenAIRE

    I. Gaspard; Zimmermann, G.

    2005-01-01

    Broadband IP-based multimedia services are rapidly growing and there is the trend to use these services everywhere. Due to the fact that passengers in long distance high speed trains have a very comfortable environment to use their own terminal equipment, e.g. laptops with IEEE802.11×WLAN capability, it seems to be very promising to deliver broadband internet into trains. The challenge is the land-train connection where a high bit data rate link, e.g. 1Mbps in average in up-...

  18. SDN-Based Broadband Network for Cloud Services

    Institute of Scientific and Technical Information of China (English)

    Xiongyan Tang; Pei Zhang; Chang Cao

    2014-01-01

    Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization (SDN/NFV) will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for intercon-nection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtu-alized residential gateway (VRG). We discuss the deployment modes of VRG.

  19. Multi-band and broadband acoustic metamaterial with resonant structures

    International Nuclear Information System (INIS)

    We design an acoustic metamaterial (AM) with multi-band of negative modulus composed of different sized split hollow spheres (SHSs). From acoustic transmitted experiment, the AM exhibits simultaneously negative modulus at frequencies 914, 1298 and 1514 Hz. Based on the multi-band designed concept, broadband AM is fabricated by arraying gradually sized SHS. The transmission results indicate that this medium can achieve negative modulus at the frequency range from 900 to 1500 Hz. This kind of broadband AM is very convenient to couple with other structures to gain the double-negative AM.

  20. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  1. Broadband Wireline Provider Service: Cable Modem - Other; BBRI_cableOther12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - Other" technology. Broadband availability is...

  2. Broadband Wireline Provider Service: Cable Modem - DOCSIS 3.0; BBRI_cableDOCSIS12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - DOCSIS 3.0" technology. Broadband availability is...

  3. Broadband Wireline Provider Service: Asymmetric xDSL; BBRI_DSLasym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Asymmetric xDSL technology. Broadband availability is summarized...

  4. Broadband Wireline Provider Service: Symmetric xDSL; BBRI_DSLsym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Symmetric xDSL technology. Broadband availability is summarized...

  5. Broadband Wireline Provider Service: Optical Carrier - Fiber to the End User; BBRI_fiber12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Optical Carrier - Fiber to the End User" technology. Broadband...

  6. 76 FR 23812 - Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects...

    Science.gov (United States)

    2011-04-28

    ... Documents in Rulemaking Proceedings, 63 FR 24121 (1998). Electronic Filers: Comments may be filed... COMMISSION Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects on Broadband Communications Networks of Damage or Failure of Network Equipment or Severe...

  7. The Impact of Broadband on U.S. Agriculture: An Evaluation of the USDA Broadband Loan Program

    OpenAIRE

    Kandilov, Amy M.G.; Kandilov, Ivan T.; Liu, Xiangping; Renkow, Mitch

    2011-01-01

    We evaluate the impact of USDA’s low-cost broadband loan programs on the U.S. agricultural sector. The broadband loan programs increase access to high-speed internet in recipient communities, which can raise farm sales by increasing both farm output and prices received by producers. Further, high-speed internet may drive down costs by providing information on cheaper inputs and better management practices, leading to an overall improvement in farm profits. Using data from the 1997, 2002, and ...

  8. A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna

    OpenAIRE

    Jianming Zhou

    2015-01-01

    A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characte...

  9. Competition and Regulation in the Retail Broadband Sector: a Holistic Approach for Pricing Policies

    OpenAIRE

    Martínez Santos, Fernando

    2015-01-01

    [eng] This thesis analyses the pricing policies used by operators when they establish broadband tariffs. The studies draw on datasets that combine broadband plans’ characteristics and tariffs with other sources of data at country level to reflect the market structure and regulation activity. The pricing models in this dissertation share the common thread of using three groups of variables to explain the level of broadband prices: 1- the characteristics of the broadband service, 2- the operat...

  10. The Evolution of South Korea's Broadband Convergence Network, 2004-2007

    Science.gov (United States)

    Menon, Siddhartha Shankar

    2010-01-01

    Broadband holds a critical position in the progress of economic and social indicators by connecting consumers, businesses and governments. South Korea has consistently been the global leader in broadband deployment since 1999. In the last ten years the Korean government has pursued several strategies for its broadband policy. The purpose of this…

  11. Libraries Use Broadband Internet Service to Serve High Need Communities. Data Note. Number 1

    Science.gov (United States)

    Pastore, Erica; Henderson, Everett

    2009-01-01

    America needs greater access to broadband Internet to spur economic growth, innovation, and job creation. To date, gains in household broadband take-up are not evenly distributed across all demographic groups or geographic areas. While from 2001 to 2007, the percentage of households in the United States with access to broadband Internet services…

  12. Community Broadband Networks and the Opportunity for E-Government Services

    DEFF Research Database (Denmark)

    Williams, Idongesit

    2016-01-01

    Community Broadband Networks (CBN) facilitate Broadband connectivity in underserved areas in many countries. The lack of Broadband connectivity is one of the reasons for the slow diffusion of e-government services in many countries.This article explains how CBNs can be enabled by governments to f...

  13. 76 FR 51271 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

    Science.gov (United States)

    2011-08-18

    ... COMMISSION 47 CFR Part 90 Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the... interoperable public safety broadband network. The establishment of a common air interface for 700 MHz public safety broadband networks will create a foundation for interoperability and provide a clear path for...

  14. Bottle microresonator broadband and low repetition rate frequency comb generator

    CERN Document Server

    Dvoyrin, V

    2016-01-01

    We propose a new type of broadband and low repetition rate frequency comb generator which has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height which is greater or equal to lambda/2pi*n0 (here lambda is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material). Overall, the microresonator possesses a broadband, small FSR, and accurately equidistant spectrum convenient for the generation of a broadband and low repetition rate optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, which radiation frequency matches a single axial eigenfrequency of the microresonator, or, alternatively, by p...

  15. A stochastic approach to robust broadband structural control

    Science.gov (United States)

    Macmartin, Douglas G.; Hall, Steven R.

    1992-01-01

    Viewgraphs on a stochastic approach to robust broadband structural control are presented. Topics covered include: travelling wave model; dereverberated mobility model; computation of dereverberated mobility; power flow; impedance matching; stochastic systems; control problem; control of stochastic systems; using cost functional; Bernoulli-Euler beam example; compensator design; 'power' dual variables; dereverberation of complex structure; and dereverberated transfer function.

  16. 76 FR 13769 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2011-03-14

    ... for low- and high-end service jobs, from call centers to software development, but does not guarantee... characteristics, suggesting that policy, economic, and social factors can overcome common barriers to broadband... especially significant given the importance of ] ongoing parental involvement in children's...

  17. Broadband for Public Libraries: Importance, Issues, and Research Needs

    Science.gov (United States)

    Mandel, Lauren H.; Bishop, Bradley Wade; McClure, Charles R.; Bertot, John Carlo; Jaeger, Paul T.

    2010-01-01

    U.S. public libraries provide free public internet services to the communities that they serve, but require robust, high-speed broadband internet connections to continue meeting public demands. The 2008-2009 "Public Library Funding & Technology Access Study" ("PLFTAS") illustrates challenges that public libraries encounter in achieving broadband…

  18. Drivers and barriers for development of alternative broadband

    DEFF Research Database (Denmark)

    Tadayoni, Reza; Sigurdsson, Halldór Matthias

    2005-01-01

    Alternative broadband infrastructures are emerging and developing very fast. Different technologies and organization/business models have been used to establish these networks. The aim of the paper is to understand and identify the technological, economic and political/regulatory drivers and barr...

  19. Broadband antireflection properties of thin heterogeneous dielectric films.

    Science.gov (United States)

    Shvartsburg, A B; Petite, G; Hecquet, P

    2000-12-01

    New exactly solvable flexible models of inhomogeneous thin film with smooth and deep variations of dielectric susceptibility epsilon(z) are presented. Formation of cutoff frequencies of such films (as well as the broadband antireflection), controlled by the profiles epsilon(z), is shown. The crucial role of gradients of epsilon(z) in the optics of strongly inhomogeneous media is emphasized. PMID:11140487

  20. Novel broadband glass phosphors for high CRI WLEDs.

    Science.gov (United States)

    Chen, Li-Yin; Cheng, Wei-Chih; Tsai, Chun-Chin; Chang, Jin-Kai; Huang, Yi-Chung; Huang, Jhih-Ci; Cheng, Wood-Hi

    2014-05-01

    New broadband glass phosphors with excellent thermal stability were proposed and experimentally demonstrated for white light-emitting-diodes (WLEDs). The novel glass phosphors were realized through dispersing multiple phosphors into SiO₂ based glass (SiO₂-Na₂O-Al₂O₃-CaO) at 680°C. Y₃Al₅O₁₂:Ce³⁺ (YAG), Lu₃Al₅O₁₂:Ce³⁺ (LuAG), and CaAlSiN₃: Eu²⁺ (nitride) phosphor crystals were chosen respectively as the yellow, green, and red emitters of the glass phosphors. The effect of sintering temperature on inter-diffusion reduction between phosphor crystals and amorphous SiO₂ in nitride-doped glass phosphors was studied and evidenced by the aid of high-resolution transmission electron microscopy (HRTEM). Broadband glass phosphors with high quantum-yield of 55.6% were thus successfully realized through the implementation of low sintering temperature. Proof-of-concept devices utilizing the novel broadband phosphors were developed to generate high-quality cool-white light with trisstimulus coordinates (x, y) = (0.358, 0.288), color-rending index (CRI) = 85, and correlated color temperature (CCT) = 3923K. The novel broadband glass phosphors with excellent thermal stability are essentially beneficial to the applications for next-generation solid-state indoor lighting, especially in the area where high power and absolute reliability are required. PMID:24922375

  1. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    Directory of Open Access Journals (Sweden)

    Xiupu Zhang

    2014-11-01

    Full Text Available Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelength, optical channelization and the others, implemented in optical domain, to suppress both even and odd order nonlinear distortion components, such as second and third order. Digital predistortion has been a widely used linearization method for RF power amplifiers. However, digital linearization that requires analog to digital converter is severely limited to hundreds of MHz bandwidth. Instead, analog and optical linearization provide broadband linearization with up to tens of GHz. Therefore, for broadband radio over fiber transmission that can be used for future broadband cloud radio access networks, analog and optical linearization are more appropriate than digital linearization. Generally speaking, both analog and optical linearization are able to improve spur-free dynamic range greater than 10 dB over tens of GHz. In order for current digital linearization to be used for broadband radio over fiber transmission, the reduced linearization complexity and increased linearization bandwidth are required. Moreover, some digital linearization methods in which the complexity can be reduced, such as Hammerstein type, may be more promising and require further investigation.

  2. K/Ka-band Antenna for Broadband Aeronautical Mobile Application

    Science.gov (United States)

    Densmore, A.

    1994-01-01

    The Jet Propulsion Laboratory (JPL) has recently begun the development of a Broadband Aeronauical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS).

  3. Nonlinear Analysis of Renal Autoregulation Under Broadband Forcing Conditions

    DEFF Research Database (Denmark)

    Marmarelis, V Z; Chon, K H; Chen, Y M;

    1994-01-01

    in describing the dynamic pressure-flow relation is found to be important. Furthermore, the dependence of 1st-order kernel waveforms on the power level of broadband pressure forcing indicates the presence of nonlinear feedback (of sigmoid type) based on previously reported analysis of a class of...... nonlinear feedback systems....

  4. Photonic crystal fiber design for broadband directional coupling

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Bang, Ole; Bjarklev, Anders Overgaard

    2004-01-01

    A novel design for a broadband directional coupler based on a photonic crystal fiber is investigated numerically. It is shown that suitable index-depressing doping of the core regions in an index-guiding twin-core photonic crystal fiber can stabilize the coupling coefficient between the cores over...

  5. Broadband microwave photonic phase shifter based on polarisation rotation

    DEFF Research Database (Denmark)

    Xue, Weiqi; Öhman, Filip; Blaaberg, Søren; Chen, Yaohui; Sales, Salvador; Mørk, Jesper

    2008-01-01

    A broadband microwave photonic phase shifter is presented based on the polarisation properties of a Mach-Zehnder intensity modulator and nonlinear polarisation rotation in a semiconductor optical amplifier. The system can realise about 150deg phase shift in the frequency range from 50 MHz to 19 GHz....

  6. China Netcom: Stressing on Broadband and Building an Innovative Enterprise

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China Network Communications Group Corporation (CNC) proposed and reaffirmed for many times the strategic objective of transferring to a broadband communication and multimedia service provider since the beginning of this year. CNC, insisting on self-innovation, is going to forge itself into a domestically high-class and internationally influential innovative company within five years.

  7. Strategies for Complex Mixture Analysis in Broadband Microwave Spectroscopy.

    Science.gov (United States)

    Steber, Amanda L.; Neill, Justin L.; Muckle, Matthew T.; Pate, Brooks H.; Plusquellic, D. F.; Lattanzi, V.; Spezzano, S.; McCarthy, M. C.

    2010-06-01

    Broadband microwave spectra often contain overlapping spectra from a large number of species in the sample mixture, whether in the study of conformational isomers, molecular complexes, reaction products from reactive molecular sources (e.g., electrical discharge), or analysis of chemical mixtures. In these experiments, the identification of individual spectra in the full spectrum through pattern recognition becomes difficult when there is a high density of transitions. Strategies for extracting individual spectra from broadband measurements are discussed. Two approaches for microwave-microwave double resonance spectroscopy have been evaluated. One uses a transition-by-transition screening in a narrowband cavity spectrometer to identify an unknown spectrum and has a time advantage from the increased sensitivity of cavity spectroscopy. The second double-resonance approach uses a broadband spectral editing approach that gives a multiplex advantage in the detection. Both of these experimental techniques are combined with computer-aided assignment algorithms to make the spectral assignment in a minimum of double-resonance observations. The performance of spectral analysis solely using computer-aided assignment is also evaluated. The potential for fully automated spectral decomposition of the broadband spectrum of a complex mixture will be described.

  8. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu

    2015-02-12

    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  9. Ultra-broadband light trapping using nanotextured decoupled graphene multilayers

    Science.gov (United States)

    Anguita, José V.; Ahmad, Muhammad; Haq, Sajad; Allam, Jeremy; Silva, S. Ravi P.

    2016-01-01

    The ability to engineer a thin two-dimensional surface for light trapping across an ultra-broad spectral range is central for an increasing number of applications including energy, optoelectronics, and spectroscopy. Although broadband light trapping has been obtained in tall structures of carbon nanotubes with millimeter-tall dimensions, obtaining such broadband light–trapping behavior from nanometer-scale absorbers remains elusive. We report a method for trapping the optical field coincident with few-layer decoupled graphene using field localization within a disordered distribution of subwavelength-sized nanotexturing metal particles. We show that the combination of the broadband light–coupling effect from the disordered nanotexture combined with the natural thinness and remarkably high and wavelength-independent absorption of graphene results in an ultrathin (15 nm thin) yet ultra-broadband blackbody absorber, featuring 99% absorption spanning from the mid-infrared to the ultraviolet. We demonstrate the utility of our approach to produce the blackbody absorber on delicate opto-microelectromechanical infrared emitters, using a low-temperature, noncontact fabrication method, which is also large-area compatible. This development may pave a way to new fabrication methodologies for optical devices requiring light management at the nanoscale. PMID:26933686

  10. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  11. Measuring Broadband IR Irradiance in the Direct Solar Beam (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 um and 50 um, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 um to 3 um, while the present photovoltaic cells are limited to approximately 0.3 um to 1 um. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and are calibrated with traceability to consensus reference, yet are calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 um to 50 um, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degrees to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  12. Measuring Broadband IR Irradiance in the Direct Solar Beam (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Konings, J.; Xie, Y.; Dooraghi, M.; Sengupta, M.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 micrometers and 50 micrometers, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 micrometers to 3 micrcometers, while the present photovoltaic cells are limited to approximately 0.3 micrometers to 1 micrometers. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus reference, yet calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 micrometers to 50 micrometers, as first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degres to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  13. Broadband circular polarizers constructed using helix-like chiral metamaterials

    Science.gov (United States)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Chen, Xiaoshuang; Lu, Wei

    2016-08-01

    In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical response. For only a four-layer helix-like metamaterial, the maximum extinction ratio can reach 19.7. The operation band is in the wavelength range of 4.69 μm to 8.98 μm with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation band. Such a structure is a promising candidate for integratable and scalable broadband circular polarizers, especially it has great potential to act as a broadband circular micropolarizer in the field of the full-Stokes division of focal plane polarimeters.In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical

  14. Broadband detuned Sagnac interferometer for future generation gravitational wave astronomy

    CERN Document Server

    Voronchev, N V; Danilishin, S L

    2015-01-01

    Broadband suppression of quantum noise below the Standard Quantum Limit (SQL) becomes a top-priority problem for the future generation of large-scale terrestrial detectors of gravitational waves, as the interferometers of the Advanced LIGO project, predesigned to be quantum-noise-limited in the almost entire detection band, are phased in. To this end, among various proposed methods of quantum noise suppression or signal amplification, the most elaborate approach implies a so-called *xylophone* configuration of two Michelson interferometers, each optimised for its own frequency band, with a combined broadband sensitivity well below the SQL. Albeit ingenious, it is a rather costly solution. We demonstrate that changing the optical scheme to a Sagnac interferometer with weak detuned signal recycling and frequency dependent input squeezing can do almost as good a job, as the xylophone for significantly lower spend. We also show that the Sagnac interferometer is more robust to optical loss in filter cavity, used f...

  15. Broadband laser polarization control with aligned carbon nanotubes

    CERN Document Server

    Yang, He; Lia, Diao; Chen, Ya; Mattila, Marco; Tian, Ying; Yong, Zhenzhong; Yang, Changxi; Tittonen, Ilkka; Ren, Zhaoyu; Bai, Jingtao; Li, Qingwen; Kauppinen, Esko I; Lipsanen, Harri; Sun, Zhipei

    2015-01-01

    We introduce a simple approach to fabricate aligned carbon nanotube (ACNT) device for broadband polarization control in fiber laser systems. The ACNT device was fabricated by pulling from as-fabricated vertically-aligned carbon nanotube arrays. Their anisotropic property is confirmed with optical and scanning electron microscopy, and with polarized Raman and absorption spectroscopy. The device was then integrated into fiber laser systems (at two technologically important wavelengths of 1 and 1.5 um) for polarization control. We obtained a linearly-polarized light output with the maximum extinction ratio of ~12 dB. The output polarization direction could be fully controlled by the ACNT alignment direction in both lasers. To the best of our knowledge, this is the first time that ACNT device is applied to polarization control in laser systems. Our results exhibit that the ACNT device is a simple, low-cost, and broadband polarizer to control laser polarization dynamics, for various photonic applications (such as ...

  16. Ultra-broadband wavelength conversion sensor using thermochromic liquid crystals

    Science.gov (United States)

    Chen, Ichun Anderson; Park, S. W.; Chen, G.; Wang, C.; Bethea, C.; Martini, R.; Woolard, D.

    2013-03-01

    Wavelength conversion (WC) imaging is a methodology that employs temperature sensitive detectors to convert photoinduced termperature into a detectable optical signal. One specific method is to use molecular detectors such as thermochromic liquid crystals (TLC), which exhibits thermochromism to observe the surface temperature of an area by observing the apparent color in the visible spectrum. Utilizing this methodology, an ultra-broadband room temperature imaging system was envisioned and realized using off the shelf thermochromic liquid crystals. The thermochromic properties of the sensor were characterized to show a thermochromic coefficient α = 10%/°K and a noise equivalent power (NEP) of 64 μW. With the TLC camera, images of both pulsed and continuous wave (CW) sources spanning 0.6 μm to 150 μm wavelengths were captured to demonstrate its potential as a portable, low-cost, and ultra-broadband imaging tool.

  17. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M

    2013-10-14

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  18. Broadband terahertz amplification in a heterogeneous quantum cascade laser.

    Science.gov (United States)

    Bachmann, Dominic; Leder, Norbert; Rösch, Markus; Scalari, Giacomo; Beck, Mattias; Arthaber, Holger; Faist, Jérôme; Unterrainer, Karl; Darmo, Juraj

    2015-02-01

    We demonstrate a broadband terahertz amplifier based on ultrafast gain switching in a quantum cascade laser. A heterogeneous active region is processed into a coupled cavity metal-metal waveguide device and provides broadband terahertz gain that allows achieving an amplification bandwidth of more than 500 GHz. The temporal and spectral evolution of a terahertz seed pulse, which is generated in an integrated emitter section, is presented and an amplification factor of 21 dB is reached. Furthermore, the quantum cascade amplifier emission spectrum of the emerging sub-nanosecond terahertz pulse train is measured by time-domain spectroscopy and reveals discrete modes between 2.14 and 2.68 THz. PMID:25836170

  19. Ultra-broadband terahertz heterogeneous quantum cascade lasers

    International Nuclear Information System (INIS)

    Full text: We report an ultra-broadband heterogeneous quantum cascade laser emitting from 2.2 to 3.2 THz. The broad gain medium is obtained by placing different active-region designs into a common double metal waveguide that provides no cutoff and excellent figure of merit over a broad wavelength range. The active-region design is based on a four quantum well design which is then rescaled to obtain emissions with center-frequencies 2.1 THz, 2.4 THz and 2.6 THz. Lasers operate up to 125 K in pulsed mode. Studying the spectral emission as function of injected current we see progressive switching on of emission from the appropriate designs. Short devices provide broad-band emission also in continuous-wave operation. We also performed time-resolved measurements using a fast superconducting bolometer and 5ns wide gate. Strong gain-competition phenomena among the designs were observed. (author)

  20. A Broadband Approach to Axion Dark Matter Detection

    CERN Document Server

    Kahn, Yonatan; Thaler, Jesse

    2016-01-01

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axion dark matter with masses in the range of 10^{-13} eV to 10^{-6} eV, particularly the QCD axion with a GUT-scale decay constant.

  1. Efficient composite broadband polarization retarders and polarization filters

    International Nuclear Information System (INIS)

    A new type of broadband polarization half-wave retarder and narrowband polarization filters are described and experimentally tested. Both, the retarders and the filters are designed as composite stacks of standard optical half-wave plates, each of them twisted at specific angles. The theoretical background of the proposed optical devices was obtained by analogy with the method of composite pulses, known from the nuclear and quantum physics. We show that combining two composite filters built from different numbers and types of waveplates, the transmission spectrum is reduced from about 700 nm to about 10 nm width.We experimentally demonstrate that this method can be applied to different types of waveplates (broadband, zero-order, multiple order, etc.)

  2. Amplifier based broadband pixel for sub-millimeter wave imaging

    Science.gov (United States)

    Sarkozy, Stephen; Drewes, Jonathan; Leong, Kevin M. K. H.; Lai, Richard; Mei, X. B. (Gerry); Yoshida, Wayne; Lange, Michael D.; Lee, Jane; Deal, William R.

    2012-09-01

    Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and 1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

  3. A Performance Study of Wireless Broadband Access (WiMAX

    Directory of Open Access Journals (Sweden)

    Maan A. S. Al-Adwany

    2011-12-01

    Full Text Available WiMAX (worldwide interoperability for microwave access is one of the wireless broadband access technologies which supplies broadband services to clients, but it surpasses other technologies by its coverage area, where one base station can cover a small city. In this paper, WiMAX technology is studied by exploring its basic concepts, applications, and advantages / disadvantages. Also a MATLAB simulator is used to verify the operation of the WiMAX system under various channel impairments and for variety of modulation schemes. From the simulation results, we found that WiMAX system works well in both AWGN and multipath fading channels, but under certain constraints that are addressed in this paper.

  4. Radiative cooling and broadband phenomenon in low-frequency waves

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial -plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves. Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period, and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabatic heating. when the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.

  5. Planar metamaterial-based beam-scanning broadband microwave antenna

    International Nuclear Information System (INIS)

    The broadband directive emission from the use of waveguided metamaterials is numerically and experimentally reported. The metamaterials, which are composed of non-resonant circular complementary closed ring structures printed on a dielectric substrate, are designed to obey the refractive index of a Luneburg lens. An arc array of planar radiating slot antennas placed at the periphery of the lens is used as wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, far-field radiation patterns have been measured. Furthermore, this metamaterial-based lens can be used to achieve beam-scanning with a coverage of up to 120 °. Far-field measurements agree qualitatively with calculated near-field distributions

  6. Broadband second harmonic generation in whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Strekalov, Dmitry V; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cyclically. The technique can be implemented with a WGM resonator with its disk plane parallel to the optic axis of the crystal. With a single beta barium borate (BBO) resonator in that configuration, we experimentally demonstrated efficient second harmonic generation (SHG) to harmonic wavelengths from 780 nm in the near infrared to 317 nm in the ultraviolet (UV). The observed SHG conversion efficiency is as high as 4.6% (mW)-1. This broadband PM technique opens a new way for nonlinear optics applications in WGM resonators. Th...

  7. Broadband and chiral binary dielectric meta-holograms.

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-05-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices' compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics. PMID:27386518

  8. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    Science.gov (United States)

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region. PMID:26907442

  9. Swift/BAT and MAXI/GSC broadband transient monitor

    Science.gov (United States)

    Sakamoto, Takanori; Oda, Ryoma; Mihara, Tatehiro; Yoshida, Atsumasa; Arimoto, Makoto; Barthelmy, Scott D.; Kawai, Nobuyuki; Krimm, Hans A.; Nakahira, Satoshi; Serino, Motoko

    2016-06-01

    We present a newly developed broadband transient monitor using the Swift Burst Alert Telescope (BAT) and the MAXI Gas Slit Camera (GSC) data. Our broadband transient monitor keeps vigil for high-energy transient sources from 2 keV to 200 keV in seven energy bands by combining the BAT (15-200 keV) and the GSC (2-20 keV) data. Currently, daily and 90-minute (one orbit) averaged light curves are available for 106 high-energy transient sources. This transient monitor is available to the public through our web server, http://yoshidalab.mydns.jp/bat_gsc_trans_mon/, for wider use by the community. We discuss a daily sensitivity of our monitor and possible future improvements on our pipeline.

  10. Global characterization of seismic noise with broadband seismometers

    OpenAIRE

    Coughlin, Michael William; Harms, Jan

    2012-01-01

    In this paper, we present an analysis of seismic spectra that were calculated from all broadband channels (BH?) made available through IRIS, NIED F-net and Orfeus servers covering the past five years and beyond. A general characterization of the data is given in terms of spectral histograms and data-availability plots. We show that the spectral information can easily be categorized in time and regions. Spectral histograms indicate that seismic stations exist in Africa, Australia and Antarctic...

  11. A Novel, Free-Space Broadband Dielectric Measurement Technique

    OpenAIRE

    Liu, YaQiang

    2014-01-01

    Frequently, when free-space electromagnetic waves pass through a material, there will be some form of interaction between the wave and the material. Measuring this change forms the basis of free-space, dielectric material measurement, where the variations will be attenuation and a phase change relative to the wave when the material was not present and are typically recorded over a broadband range of frequencies. In this work a new technique is presented to accurately perform free-space bro...

  12. Ultra-Broadband Acoustic Metasurface for Manipulating the Reflected Waves

    OpenAIRE

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2014-01-01

    We have designed and experimentally realized an ultra-broadband acoustic metasurface (UBAM) capable of going beyond the intrinsic limitation of bandwidth in existing designs of optical/acoustical metasurfaces. Both the numerical and experimental results demonstrate that the UBAM made of subwavelength gratings can manipulate the reflected phase-front within a bandwidth larger than 2 octaves. A simple physical model based on the phased array theory is developed for interpreting this extraordina...

  13. Robust Two-Dimensional FIR Filter Design for Broadband Beamformers

    OpenAIRE

    Nordebo, Sven

    1995-01-01

    With conventional least squares or Chebyshev approximation methods in the design of a fixed, broadband, delay{and{sum beamformer, the filter weight values may become excessively large. This anomaly is due to large, unspecified regions of the corresponding two{dimensional FIR filter frequency plane. With large filter weight values, the frequency response of the resulting beamformer may be severely degraded due to inaccuracies in sensor positions and/or sensor frequency response. For an adaptiv...

  14. Fiber Optic Broadband Ultrasonic Probe for Virtual Biopsy: Technological Solutions

    OpenAIRE

    Biagi, E.; Cerbai, S.; Masotti, L.; L. Belsito; A. RONCAGLIA; Masetti, G.; N. Speciale

    2010-01-01

    An ultrasonic probe was developed by using, in conjunction, optoacoustic and acousto-optic devices based on fiber optic technology. The intrinsic high frequency and wide bandwidth associated both to the opto-acoustic source and to the acousto-optic receiving element could open a way towards a “virtual biopsy” of biological tissue. A Micro-Opto-Mechanical-System (MOMS) approach is proposed to realize the broadband ultrasonic probe on micromachined silicon frames suited to be mounted on the tip...

  15. Architecture For Delivery Of Broadband Services To The Residence

    Science.gov (United States)

    Coathup, Larry; Goddard, G. W.; McEachern, James; Bears, James

    1990-01-01

    This paper presents a technology and architecture perspective of the cost of evolving today's copper access network, optimized for POTS, to a fiber access network providing both narrowband and broadband services. Architectures are assessed using application studies based on cost models for actual routes in North America. This study identifies three architectures as serious candidates (i.e., close to copper in cost) for providing POTS service in 1992: the double star, the active pedestal and the star-bus.

  16. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

    OpenAIRE

    Reyes Reyes, A.; Hou, Z.; Van Mastrigt, E.; Horsten, R.C.; J. C. De Jongste; Pijnenburg, M. W.; Urbach, H.P.; Bhattacharya, N.

    2014-01-01

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm−1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present in a complex gas mixture without any pre-treatment in two minutes. We demonstrate that we can detect sub-ppmv concentration of acetone in presence of 2% of water at the same wavenumber region.

  17. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy.

    Science.gov (United States)

    Reyes-Reyes, A; Hou, Z; van Mastrigt, E; Horsten, R C; de Jongste, J C; Pijnenburg, M W; Urbach, H P; Bhattacharya, N

    2014-07-28

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm(-1). Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present in a complex gas mixture without any pre-treatment in two minutes. We demonstrate that we can detect sub-ppmv concentration of acetone in presence of 2% of water at the same wavenumber region. PMID:25089450

  18. Multiplexed broadband beam steering system utilizing high speed MEMS mirrors

    OpenAIRE

    Knoernschild, Caleb; Kim, Changsoon; Lu, Felix P.; Kim, Jungsang

    2009-01-01

    We present a beam steering system based on micro-electromechanical systems technology that features high speed steering of multiple laser beams over a broad wavelength range. By utilizing high speed micromirrors with a broadband metallic coating, our system has the flexibility to simultaneously incorporate a wide range of wavelengths and multiple beams. We demonstrate reconfiguration of two independent beams at different wavelengths (780 and 635 nm) across a common 5x5 array with 4 us settlin...

  19. Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

    OpenAIRE

    Jingyan Mo; Wei Liu; Weidong Fang; Haigao Xue; Zhongchao Lin

    2016-01-01

    This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA). The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values...

  20. Broadband opportunity in Europe’s new member states

    Czech Academy of Sciences Publication Activity Database

    Hill, G.; Kuchar, Anton; Blazic, B.; Granat, J.; Kolias, C.

    [Bordeaux]: BREAD , 2005, W01B.01--. [Broadband Europe 2005. Bordeaux (FR), 12.12.2005-14.12.2005] Grant ostatní: BReATH Consortium EU(XE) EC FP6 1ST Programme Institutional research plan: CEZ:AV0Z20670512 Keywords : Internet * telecommunication networks * cable television Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.bbeurope.org Parallel Sesion WO0B - Regional Projects I

  1. Textile broadband e-patch at ISM band

    OpenAIRE

    Paul, DL; Klemm, M; Railton, CJ; McGeehan, JP

    2007-01-01

    This paper presents early results of an investigation into the fabrication of a textile E-shaped patch antenna suitable for broadband communications in the ISM band (2.4 GHz - 2.5 GHz). The design was inspired from literature and further tuned using in-house FDTD software. The textile antenna compares reasonably well with the same antenna in conventional technology featuring 17% bandwidth with a centre frequency of 2.4 GHz and good radiation patterns

  2. Global Optimization and Broadband Analysis Software for Interstellar Chemistry (GOBASIC)

    Science.gov (United States)

    Rad, Mary L.; Zou, Luyao; Sanders, James L.; Widicus Weaver, Susanna L.

    2016-01-01

    Context. Broadband receivers that operate at millimeter and submillimeter frequencies necessitate the development of new tools for spectral analysis and interpretation. Simultaneous, global, multimolecule, multicomponent analysis is necessary to accurately determine the physical and chemical conditions from line-rich spectra that arise from sources like hot cores. Aims: We aim to provide a robust and efficient automated analysis program to meet the challenges presented with the large spectral datasets produced by radio telescopes. Methods: We have written a program in the MATLAB numerical computing environment for simultaneous global analysis of broadband line surveys. The Global Optimization and Broadband Analysis Software for Interstellar Chemistry (GOBASIC) program uses the simplifying assumption of local thermodynamic equilibrium (LTE) for spectral analysis to determine molecular column density, temperature, and velocity information. Results: GOBASIC achieves simultaneous, multimolecule, multicomponent fitting for broadband spectra. The number of components that can be analyzed at once is only limited by the available computational resources. Analysis of subsequent sets of molecules or components is performed iteratively while taking the previous fits into account. All features of a given molecule across the entire window are fitted at once, which is preferable to the rotation diagram approach because global analysis is less sensitive to blended features and noise features in the spectra. In addition, the fitting method used in GOBASIC is insensitive to the initial conditions chosen, the fitting is automated, and fitting can be performed in a parallel computing environment. These features make GOBASIC a valuable improvement over previously available LTE analysis methods. A copy of the sofware is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A23

  3. Broadband detection of squeezed vacuum: A spectrum of quantum states

    OpenAIRE

    Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1999-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtai...

  4. Magnetically tunable broadband transmission through a single small aperture

    OpenAIRE

    Ke Bi; Wenjun Liu; Yunsheng Guo; Guoyan Dong; Ming Lei

    2015-01-01

    Extraordinary transmission through a small aperture is of great interest. However, it faces a limitation that most of approaches can not realize the tunable transmission property, which is not benefit for the miniaturization of the microwave system. Here, we demonstrate a magnetically tunable broadband transmission through a small aperture. By placing two ferrite rods symmetrically on both sides of a single small aperture, the strongly localized electromagnetic fields are effectively coupled ...

  5. Plasmonic Micro Lens for Extraordinary Transmission of Broadband Light

    OpenAIRE

    Sumit Saxena; Raghvendra Pratap Chaudhary; Abhay Singh; Saurabh Awasthi; Shobha Shukla

    2014-01-01

    Extraordinary transmittance and focusing of light in quasi far field region using miniaturized optical devices is a daunting task. A polarization independent, broadband, planar metallic transmissive micro aperture capable of achromatically focusing visible light in quasi far field region is proposed. The calculated enhancement factor of transmission efficiency was about ~2.2. The total transmission after the aperture is about 60%. This high throughput focusing device will open new avenues for...

  6. Broadband second harmonic generation in whispering gallery mode resonators

    OpenAIRE

    Lin, Guoping; Fürst, Josef U.; Strekalov, Dmitry V.; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cycli...

  7. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    OpenAIRE

    Staude, Isabelle; Ivan S. Maksymov; Decker, Manuel; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Jagadish, Chennupati; Kivshar, Yuri S.

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly r...

  8. Broadband sum frequency generation via chirped quasi-phase-matching

    OpenAIRE

    Rangelov, A. A.; Vitanov, N. V.

    2011-01-01

    An efficient broadband sum frequency generation (SFG) technique using the two collinear optical parametric processes \\omega 3=\\omega 1+\\omega 2 and \\omega 4=\\omega 1+\\omega 3 is proposed. The technique uses chirped quasi-phase-matched gratings, which, in the undepleted pump approximation, make SFG analogous to adiabatic population transfer in three-state systems with crossing energies in quantum physics. If the local modulation period %for aperiodically poled quasi-phase-matching first makes ...

  9. Entry Threat and Entry Deterrence: The Timing of Broadband Rollout

    OpenAIRE

    Mo Xiao; Orazem, Peter F.

    2007-01-01

    Past empirical literature provides strong evidence that competition increases when new firms enter a market. However, rarely have economists been able to examine how competition changes with the threat of entry. This paper uses the evolution of the zip code level market structure of facilities-based broadband providers from 1999 to 2004 to investigate how a firm adjusts its entry strategy when facing the threat of additional entrants. We identify the potential entrant into a local market as t...

  10. Simultaneous Information and Power Transfer for Broadband Wireless Systems

    OpenAIRE

    Huang, Kaibin; Larsson, Erik G.

    2013-01-01

    Far-field microwave power transfer (MPT) will free wireless sensors and other mobile devices from the constraints imposed by finite battery capacities. Integrating MPT with wireless communications to support simultaneous wireless information and power transfer (SWIPT) allows the same spectrum to be used for dual purposes without compromising the quality of service. A novel approach is presented in this paper for realizing SWIPT in a broadband system where orthogonal frequency division multipl...

  11. Broadband internet: An information superhighway to sex crime?

    OpenAIRE

    Bhuller, Manudeep; Havnes, Tarjei; Leuven, Edwin; Mogstad, Magne

    2012-01-01

    Does internet use trigger sex crime? We use unique Norwegian data on crime and internet adoption to shed light on this question. A public program with limited funding rolled out broadband access points in 2000–2008, and provides plausibly exogenous variation in internet use. Our instrumental variables estimates show that internet use is associated with a substantial increase in both reports, charges and convictions of rape and other sex crimes. We present a conceptual framework that highlight...

  12. Broadband Wireless Channel measurements for high speed trains

    OpenAIRE

    Kaltenberger, Florian; BYIRINGIRO, Auguste; Arvanitakis, George; GHADDAB, Ryad; NUSSBAUM, Dominique; Knopp, Raymond; Berbineau, Marion; Cocheril, Yann; Philippe, Henri

    2014-01-01

    We describe a channel sounding measurement campaign for cellular broadband wireless communications with high speed trains that was carried out in the context of the project CORRIDOR. The campaign combines MIMO and carrier aggregation to achieve very highth roughputs. We compare two different scenarios, the first one reflects a cellular deployment, where the base station is about 1 km away from the railway line. The second scenario corresponds to a railway deployed network, where the base stat...

  13. Broadband bow-tie antenna with tapered balun

    OpenAIRE

    Jaafar, Hussein Mohammed

    2014-01-01

    ABSTRACT: In microwave applications spectrum Industrial, Scientific and Medical (ISM) band, especially in wireless communication systems applications such as GSM, 3G, Wi-Fi and Wi-MAX applications, high antenna characteristics such as high gain and wide bandwidth are required. In this thesis, a broadband Bow Tie Antenna (BTA) with high performance characteristics has been designed, to cover the wireless application requirements. One of the fundamental problems of the transmission line in the ...

  14. Swift/BAT and MAXI/GSC broadband transient monitor

    Science.gov (United States)

    Sakamoto, Takanori; Oda, Ryoma; Mihara, Tatehiro; Yoshida, Atsumasa; Arimoto, Makoto; Barthelmy, Scott Douglas; Kawai, Nobuyuki; Krimm, Hans A.; Nakahira, Satoshi; Serino, Motoko

    2016-04-01

    "Time-domain astronomy" is one of the frontier field of astronomy for the next decade. Since the most of the transient sources show the temporal variation in a broad spectral range, it would be ideal to have the real time transient monitor which covers a wide energy band. We present the newly developed broadband transient monitor using the Swift Burst Alert Telescope (BAT) and the MAXI Gas Slit Camera (GSC) data. Our broadband transient monitor monitors high-energy transient sources from 2 keV to 200 keV in seven energy bands by combining the BAT (15-200keV) and the GSC (2-20keV) data. Currently, daily and 90-minute (one orbit) averaged light curves are available for 106 high-energy transient sources. Our broadband transient monitor is available to the public through our web server, http://yoshidalab.mydns.jp/bat_gsc_trans_mon/, for wider use by the community. We discuss the daily sensitivity of our monitor and possible future improvements to our pipeline.

  15. Sound localization of aerial broadband noise in pinnipeds

    Science.gov (United States)

    Holt, Marla M.; Schusterman, Ronald J.; Kastak, David; Southall, Brandon L.

    2003-04-01

    Pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system in order to coordinate their reproductive activities. How well do they localize these types of signals? In this study, the aerial sound localization acuities of a harbor seal (Phoca vitulina), a California sea lion (Zalophus californianus), and a northern elephant seal (Mirounga angustirostris) were measured in the horizontal plane with a broadband white noise stimulus. Testing was conducted in a hemi-anechoic chamber using a left/right forced choice procedure to measure the minimum audible angle (MAA) for each subject. MAAs were defined as half the angular separation of two sound sources relative to a subject's midline that corresponded to 75% correct discrimination. MAAs were 3.6, 4.2, and 4.7 deg for the harbor seal, California sea lion, and northern elephant seal, respectively. These results demonstrate that these pinniped species had sound localization abilities comparable to the domestic cat and rhesus macaques. The acuity differences between our subjects were small, were not predicted by head size, and therefore likely reflect the relatively acute abilities of other pinniped species to localize aerial broadband signals.

  16. A NOVEL QOS SCHEDULING FOR WIRELESS BROADBAND NETWORKS

    Directory of Open Access Journals (Sweden)

    D. David Neels Pon Kumar

    2010-09-01

    Full Text Available During the last few years, users all over the world have become more and more familiar to the availability of broadband access. When users want broadband Internet service, they are generally restricted to a DSL (Digital Subscribers Line, or cable-modem-based connection. Proponents are advocating worldwide interoperability for microwave access (WiMAX, a technology based on an evolving standard for point-to multipoint wireless networking. Scheduling algorithms that support Quality of Service (QoS differentiation and guarantees for wireless data networks are crucial to the deployment of broadband wireless networks. The performance affecting parameters like fairness, bandwidth allocation, throughput, latency are studied and found out that none of the conventional algorithms perform effectively for both fairness and bandwidth allocation simultaneously. Hence it is absolutely essential for an efficient scheduling algorithm with a better trade off for these two parameters. So we are proposing a novel Scheduling Algorithm using Fuzzy logic and Artificial neural networks that addresses these aspects simultaneously. The initial results show that a fair amount of fairness is attained while keeping the priority intact. Results also show that maximum channel utilization is achieved with a negligible increment in processing time.

  17. Broadband illumination of superconducting pair breaking photon detectors

    Science.gov (United States)

    Guruswamy, T.; Goldie, D. J.; Withington, S.

    2016-04-01

    Understanding the detailed behaviour of superconducting pair breaking photon detectors such as Kinetic Inductance Detectors (KIDs) requires knowledge of the nonequilibrium quasiparticle energy distributions. We have previously calculated the steady state distributions resulting from uniform absorption of monochromatic sub gap and above gap frequency radiation by thin films. In this work, we use the same methods to calculate the effect of illumination by broadband sources, such as thermal radiation from astrophysical phenomena or from the readout system. Absorption of photons at multiple above gap frequencies is shown to leave unchanged the structure of the quasiparticle energy distribution close to the superconducting gap. Hence for typical absorbed powers, we find the effects of absorption of broadband pair breaking radiation can simply be considered as the sum of the effects of absorption of many monochromatic sources. Distribution averaged quantities, like quasiparticle generation efficiency η, match exactly a weighted average over the bandwidth of the source of calculations assuming a monochromatic source. For sub gap frequencies, however, distributing the absorbed power across multiple frequencies does change the low energy quasiparticle distribution. For moderate and high absorbed powers, this results in a significantly larger η-a higher number of excess quasiparticles for a broadband source compared to a monochromatic source of equal total absorbed power. Typically in KIDs the microwave power absorbed has a very narrow bandwidth, but in devices with broad resonance characteristics (low quality factors), this increase in η may be measurable.

  18. Broadband circulator based on spoof surface plasmon polaritons

    Science.gov (United States)

    Qiu, Tianshuo; Wang, Jiafu; Li, Yongfeng; Wang, Jun; Qu, Shaobo

    2016-09-01

    In this paper, we proposed a method to design broadband circulators with a compact size. We show that spoof surface plasmon polaritons (SSPPs), which are mediated by metallic blade structures, can be used for the design. The SSPPs wave on metallic blade structures and the transverse electromagnetic (TEM) wave on strip lines are combined to realize wideband circulation performance. A broadband characteristic, which is different from a traditional one, with a compact size can be achieved by combining the SSPPs wave and the TEM wave, which propagates simultaneously in the circulator. The simulation results indicate that from 4.5 GHz to 14 GHz, the return loss and isolation degree basically reaches up to 12 dB and 15 dB, respectively. The mechanism of the broadband transmission characteristic is analyzed using field distributions obtained in simulation. Moreover, the insertion loss is less than 1 dB. This method is helpful to reduce the size of the device and the bulk of ferrite.

  19. Broadband distortion modeling in Lyman-$\\alpha$ forest BAO fitting

    CERN Document Server

    Blomqvist, Michael; Bautista, Julian E; Ariño, Andreu; Busca, Nicolás G; Miralda-Escudé, Jordi; Slosar, Anže; Font-Ribera, Andreu; Margala, Daniel; Schneider, Donald P; Vazquez, Jose A

    2015-01-01

    In recent years, the Lyman-$\\alpha$ absorption observed in the spectra of high-redshift quasars has been used as a tracer of large-scale structure by means of the three-dimensional Lyman-$\\alpha$ forest auto-correlation function at redshift $z\\simeq 2.3$, but the need to fit the quasar continuum in every absorption spectrum introduces a broadband distortion that is difficult to correct and causes a systematic error for measuring any broadband properties. We describe a $k$-space model for this broadband distortion based on a multiplicative correction to the power spectrum of the transmitted flux fraction that suppresses power on scales corresponding to the typical length of a Lyman-$\\alpha$ forest spectrum. Implementing the distortion model in fits for the baryon acoustic oscillation (BAO) peak position in the Lyman-$\\alpha$ forest auto-correlation, we find that the fitting method recovers the input values of the linear bias parameter $b_{F}$ and the redshift-space distortion parameter $\\beta_{F}$ for mock dat...

  20. High-resolution Precipitation and Lightning Monitoring by the Ku-band Broadband Radar and the VHF Broadband Digital Interferometer

    Science.gov (United States)

    Nakamura, Yoshitaka; Yoshikawa, Eiichi; Akita, Manabu; Morimoto, Takeshi; Ushio, Tomoo; Kawasaki, Zen-Ichiro; Saito, Toshiya; Nishida, Takashi; Sakazume, Norio

    We propose a high-resolution precipitation and lightning monitoring for meteorological application. This monitoring is mainly utilized the Ku-band broadband radar (BBR) and the VHF broadband digital interferometer (DITF). The BBR can accurately measure the radar reflectivity factor and the mean Doppler velocity with 5 m resolution over a range from 40 m to several kilometers for 10 W power using a pulse compression technique. The two or more DITFs make us visualize lightning channel propagations in three dimensions. Moreover, we add new functions that integrate these observation data and disclose integration analyses results with the quasi real-time information disclosure system. Initial observations for severe storms with lightning during summer and winter thunderstorm season by these monitoring instruments indicate that we obtain detailed precipitation distribution and detect active convective cells with lightning discharges.

  1. ANALYSIS OF THE ISSUES OF EFFECTIVE BROADBAND MEDIA SERVICES DEPLOYMENT IN THE COMPUTER COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Dr.S.S.Riaz Ahamed

    2010-06-01

    Full Text Available Fast Internet access barely scratches the surface of the powers of broadband, DSL, and IP technology, which, combined in broadband media services, will connect people and businesses around the world like never before. Broadband media services will put the consumer in total control by enabling personal, custom, on-demand viewing of entertainment, e-learning, video games, and other types of content. Individuals will choose what they want to hear, see, or be entertained by on their own, and people will no longer have to plan around preconceived broadcast schedules for home entertainment. A broadband media service provides endless possibilities for consumers to choose and personalize their entertainment and infotainment. A brief history tracing the evolution of broadband media services will be presented, along with descriptions of multimedia standards, potential services, and the roles of the various entities involved in creating broadband media services–network providers, content providers, services providers, and businesses and consumers.

  2. 将宽带梦想接入现实%Broadband Dream Accessing Reality

    Institute of Scientific and Technical Information of China (English)

    夏竞辉

    2005-01-01

    Now the developing roadmap of “Industrialization Driven by Information Technology” and the industry strategy of “Telecom Giant” are both conformed, which means that the development of broadband industry and its market will be supported by the government, In addition, the Digital Olympics plan of “Establishing the 2008 Olympics as the First Real Broadband Olympics” will give great powers to the broadband development in China, In view of the great importance of broadband development now in China, in this issue “New Telecom Salon” focuses on broadband services development, And we are horned to invite all the experts in this field. They will show us the new image of broadband industry development by discussion here,

  3. Universal Broadband: An Analysis of Global Stakeholders and the Pursuit of the Common Good

    OpenAIRE

    David J. Yates; Joseph W. Weiss

    2010-01-01

    A new digital divide is emerging both within and between nations that is due to inequalities in broadband Internet access. To bridge the global broadband divide, organizations and individuals must collaborate to provide broadband access to a converged high-speed Internet for both rich and poor citizens worldwide. The authors argue that addressing this global problem is an ethical imperative that requires bridging the perspectives of multiple stakeholders and applying their collective resource...

  4. Business Models for Mobile Broadband Media Services : A case study about the Indian Market

    OpenAIRE

    Selvakumar, Ekambar

    2012-01-01

    The emergence of Mobile broadband media services creates high expectations among end users and constant challenges among the Mobile network operators. Due to large number of applications for voice and messaging embedded in this Mobile broadband media services, the operators are facing fall in revenue in their traditional voice and SMS services. Now it is the suitable time for the operators to make a shift in their business to provide services via Mobile broadband which could help them improve...

  5. Are tv-viewers and surfers different breeds? : broadband demand and asymmetric cross-price effects

    OpenAIRE

    Andersson, Kjetil; Fjell, Kenneth; Foros, Øystein

    2003-01-01

    We consider two different qualities of broadband access, one that simply means greater access speed to Internet applications and content and a premium version that also gives access to interactive TV-centric applications. Based on a market survey we find that potential consumers of this premium broadband access do not consider basic broadband Internet access as a substitute. The price of the basic Internet-centric service does not constrain the price that may be charged for the premium TV-cen...

  6. Broadband MC DS-CDMA Using Space-Time and Frequency-Domain Spreading

    OpenAIRE

    Yang, L-L.; Hanzo, L.

    2002-01-01

    In this contribution multicarrier direct-sequence codedivision multiple-access (MC DS-CDMA) using space-time spreading (STS) assisted transmit diversity and frequency-domain (F-domain) spreading is investigated in the context of broadband communications over frequency-selective Rayleigh fading channels. We consider the attainable capacity extension of broadband MC DS-CDMA with the advent of using Time-Frequency-domain (TF-domain) spreading. The BER performance of STS assisted broadband MC DS-...

  7. PERFORMANCE ANALYSIS AND SPECIAL ISSUES OF WIRELESS BROADBAND SYSTEMS IN THE INFORMATION AND COMMUNICATION ENVIRONMENT

    OpenAIRE

    Dr.S.S.Riaz Ahamed

    2010-01-01

    Wireless broadband Internet access uses many frequency bands. Wireless broadband modems offer similar performance to cable modems operating over wired cable television systems (CATV), but the business is easier to enter as the transmitters cover an entire city or region. A broadband wireless system can deliver up to 30-Mbps data capacity in a 6-MHz channel. The wireless system's strength is that it can quickly provide high burst speed Internet access to a 10-mile, 20-mile, or 35-mile radius d...

  8. Research and action agenda for a national broadband initiative in India

    OpenAIRE

    Jain, Rekha; Dass, Rajanish

    2011-01-01

    Broadband has found to have substantial impact on the economic growth of various nations. Recognizing the positive impact of broadband, several countries have gone ahead with their respective broadband plans, which, at times, include requisite fiscal stimulus. In this paper we have tried to look into several of these international examples and have tried to put forth the challenges and opportunities that exist in a fast developing country like India. Based on these experiences, observations a...

  9. FUZZY REQUIREMENT BASED STRATEGY OF QoS SERVICE FOR BROADBAND TELECOMMUNICATION NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A fuzzy requirement based strategy for QoS service in broadband networks was presented. With the analysis of QoS service in ATM networks and broadband IP networks, it gave a requirement-based strategy for QoS service application with Fuzzy language evaluation principles. The requirement parameters are chosen according to the WANT/COST rule, and a fuzzy set is constructed to realize the fuzzy determinant. The simulation results show that it is useful to evaluate the QoS service in broadband networks, and to effectively simplify the access protocols and solve the billing issues in broadband networks.

  10. Investigation of stimulated Brillouin scattering for broadband KrF laser

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Hui; Lǘ Zhi-Wei; Lin Dian-Yang; Wang Chao; Zhao Xiao-Yan; Tang Xiu-Zhang; Zhang Hai-Feng; Shan Yu-Sheng

    2004-01-01

    Stimulated Brillouin scattering (SBS) numerical mode for broadband multimode KrF laser pump with optical breakdown has been built up in this paper. The basic premises of the model are that KrF spectrum is composed of a number of lines and SBS arises from these lines with coupling to some extent. The broadband SBS threshold strongly depends on pump bandwidth. SBS and optical breakdown occur nearly simultaneously when broadband SBS and breakdown have the same threshold. The decrease of saturation reflectivity for broadband pump radiation is explained with this model. Experimental results agree well with the model.

  11. Empirical analysis of mobile broadband adoption in major six countries from the view of competition policy

    OpenAIRE

    Shinohara, Sobee; Morikawa, Hiroyuki; TSUJI, Masatsugu

    2014-01-01

    The purpose of this paper is to study competition policy on mobile broadband, consisting of 3G and 4G (LTE).Currently mobile broadband has been developing rapidly and its access speed amounts to 150Mbps for the latest 4G, which is similar to fixed broadband. This paper analyzesthe factors affect the mobile broadband adoption in major six countries,such as the U.S., UK, France, Germany, Japan, and Korea,those cover more than fifty percentof total population and adoption ratio of OECD 34 member...

  12. Highly Reflecting, Broadband Deformable Membrane Mirror for Wavefront Control Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I STTR project will develop a highly reflecting, broadband, radiation resistant, low-stress and lightweight, membrane integrated into an...

  13. The monterey bay broadband ocean bottom seismic observatory

    Directory of Open Access Journals (Sweden)

    R. Uhrhammer

    2006-06-01

    Full Text Available We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB in Monterey Bay, California (USA, 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI and the Berkeley Seismological Laboratory (BSL. The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate boundary fault system. In addition to a 3-component CMG-1T seismometer package, the station comprises a current meter and Differential Pressure Gauge, both sampled at high-enough frequency (1 Hz to allow the study of relations between background noise on the seismometers and ocean waves and currents. The proximity of several land-based broadband seismic stations of the Berkeley Digital Seismic Network allows insightful comparisons of land/ocean background seismic noise at periods relevant to regional and teleseismic studies. The station is currently autonomous. Recording and battery packages are exchanged every 3 months during scheduled one day dives. Ultimately, this station will be linked to shore using continuous telemetry (cable and/or buoy and will contribute to the earthquake notification system in Northern California. We present examples of earthquake and noise data recorded during the first 6 months of operation of MOBB. Lessons learned from these and continued recordings will help understand the nature and character of background noise in regional off-shore environments and provide a reference for the installation of future off-shore temporary and permanent broadband seismic stations.

  14. Acoustic Environment of Admiralty Inlet: Broadband Noise Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.; Carlson, Thomas J.; Myers, Joshua R.; Weiland, Mark A.; Jones, Mark E.

    2011-09-30

    Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the highly endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines at Admiralty Inlet. Of particular concern is the potential for blade strike or other negative interactions between the SRKW and the tidal turbine. A variety of technologies including passive and active monitoring systems are being considered as potential tools to determine the presence of SRKW in the vicinity of the turbines. Broadband noise level measurements are critical for the determination of design and operation specifications of all marine and hydrokinetic energy capture technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array (VLA) with four calibrated hydrophones. The sound pressure level (SPL) power spectrum density was estimated based on the fast Fourier transform. This study describes the first broadband SPL measurements for this site at different depths with frequency ranging from 10 kHz to 480 kHz in combination with other information. To understand the SPL caused by this bedload transport, three different pressure sensors with temperature and conductivity were also assembled on the VLA to measure the conditions at the hydrophone deployment depth. The broadband SPL levels at frequency ranges of 3 kHz to 7 kHz as a function of depth were estimated. Only the hydrophone at an average depth of 40 m showed the strong dependence of SPL with distance from the bottom, which was possibly caused by the cobbles shifting on the seabed. Automatic Identification System data were also studied to understand the SPL measurements.

  15. The monterey bay broadband ocean bottom seismic observatory

    OpenAIRE

    Romanowicz, B.; Seismological Laboratory, University of California, Berkeley; Stakes, D.; Monterey Bay Aquarium Research Institute; Dolenc, D.; Seismological Laboratory, University of California, Berkeley; Neuhauser, D.; Seismological Laboratory, University of California, Berkeley; McGill, P.; Monterey Bay Aquarium Research Institute; Uhrhammer, R.; Seismological Laboratory, University of California, Berkeley; Ramirez, T.; Monterey Bay Aquarium Research Institute

    2006-01-01

    We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB) in Monterey Bay, California (USA), 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate...

  16. The monterey bay broadband ocean bottom seismic observatory

    OpenAIRE

    R. Uhrhammer; McGill, P; Neuhauser, D; D. Dolenc; D. Stakes; B. Romanowicz; Ramirez, T.

    2006-01-01

    We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB) in Monterey Bay, California (USA), 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate boundary fault...

  17. Broadband manipulation of acoustic wavefronts by pentamode metasurface

    Science.gov (United States)

    Tian, Ye; Wei, Qi; Cheng, Ying; Xu, Zheng; Liu, Xiaojun

    2015-11-01

    An acoustic metasurface with a sub-wavelength thickness can manipulate acoustic wavefronts freely by the introduction of abrupt phase variation. However, the existence of a narrow bandwidth and a low transmittance limits further applications. Here, we present a broadband and highly transparent acoustic metasurface based on a frequency-independent generalized acoustic Snell's law and pentamode metamaterials. The proposal employs a gradient velocity to redirect refracted waves and pentamode metamaterials to improve impedance matching between the metasurface and the background medium. Excellent wavefront manipulation based on the metasurface is further demonstrated by anomalous refraction, generation of non-diffracting Bessel beam, and sub-wavelength flat focusing.

  18. Application of Planar Broadband Slow-Wave Systems

    Directory of Open Access Journals (Sweden)

    Edvardas Metlevskis

    2012-04-01

    Full Text Available Different types of planar broadband slow-wave systems are used for designing microwave devices. The papers published by Lithuanian scientists analyze and investigate the models of helical and meander slow-wave systems. The article carefully examines the applications of meander slow-wave systems and presents the areas where similar systems, e.g. mobile devices, RFID, wireless technologies are used and reviewed nowadays. The paper also focuses on the examples of the papers discussing antennas, filters and couplers that contain designed and fabricated meander slow-wave systems.Article in Lithuanian

  19. Broadband transmitter for pulse nuclear quadrupole resonance spectrometer

    International Nuclear Information System (INIS)

    A broadband transmitter, comprising a radiofrequency pulse shaper and power amplifier with gating system, is described. The transmitter operation frequency range is 0.1-60 MHz, power amplification factor is 40 db at nonuniformity ≤ 3 db, output power is 1 kW. Suppression factor of the carrier frequency during interruption of radio frequency pulse shaper constitutes 80 db. Moreover, the suppression factor increases at the expense of the power amplifier supply modulation. Amplification stages are produced using the KP901, KP904 field effect transistors

  20. A Broadband Micro-machined Far-Infrared Absorber

    CERN Document Server

    Wollack, Edward J; Jhabvala, Christine A; Miller, Kevin H; Quijada, Manuel A

    2016-01-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is $>\\,0.95$ from ${\\rm 1-20\\,THz}$ (${\\rm 300-15\\,\\mu m}$) over a temperature range spanning ${\\rm 5-300\\,K}$. The meta-material, realized from an array of tapers ${\\rm \\approx 100\\,\\mu m}$ in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  1. Intracavity generation of broadband biphotons in a thin crystal

    International Nuclear Information System (INIS)

    We propose and realize a method of high intensity generation of broadband biphotons and achieve its value up to 150 THz. The source is based on a thin BBO crystal with a thickness of 100 microns, in which spontaneous parametric down-conversion takes place. To compensate for the intensity decrease of the down-conversion caused by the small thickness of the crystal, it is placed inside the cavity of an Ar+ laser. In general, this experiment relates to the widely discussed problem of two-photon shaping in the frequency and/or angular domain. (letter)

  2. Coherent Lensless imaging with Ultra-Broadband Light Sources

    Directory of Open Access Journals (Sweden)

    Eikema K. S. E.

    2013-03-01

    Full Text Available We demonstrate a method for efficient lensless imaging using ultra-broadband light sources. By using a pair of time-delayed, coherent pulses in a Fourier-transform scheme, spectrally resolved diffraction patterns are obtained throughout the entire spectrum of the incident light source. We perform a proof-of-principle experiment using an octave-spanning visible light source, and obtain images of a holographic test sample with near-diffraction limited resolution. Our approach provides a promising route towards efficient high-resolution imaging using table-top high-harmonic soft-X-ray sources.

  3. Metallic subwavelength structures for a broadband infrared absorption control

    Science.gov (United States)

    Biener, Gabriel; Niv, Avi; Kleiner, Vladimir; Hasman, Erez

    2007-04-01

    We present a method to control the absorption of a resonator by using a subwavelength structure consisting of thin metallic plates that behaves as a metamaterial film. We demonstrate the ability to tailor the conductivity of such a metallic subwavelength structure to achieve a resonator with the desired impedance matching for the mid-infrared range. This approach provides for broadband, as well as broad-angle, enhanced absorption. Theoretical analyses, as well as experimental results of the optical properties of a metallic NiCr structure at 8-12 μm spectral range are introduced.

  4. A broadband micro-machined far-infrared absorber

    Science.gov (United States)

    Wollack, E. J.; Datesman, A. M.; Jhabvala, C. A.; Miller, K. H.; Quijada, M. A.

    2016-05-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is >0.95 from 1 to 20 THz (300-15 μm) over a temperature range spanning 5-300 K. The meta-material, realized from an array of tapers ≈100 μm in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  5. Frequency Comb Assisted Broadband Precision Spectroscopy with Cascaded Diode Lasers

    CERN Document Server

    Liu, Junqiu; Pfeiffer, Martin H P; Kordts, Arne; Kamel, Ayman N; Guo, Hairun; Geiselmann, Michael; Kippenberg, Tobias J

    2016-01-01

    Frequency comb assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this letter we present a novel method using cascaded frequency agile diode lasers, which allows extending the measurement bandwidth to 37.4 THz (1355 to 1630 nm) at MHz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy and in particular it enables to characterize the dispersion of integrated microresonators up to the fourth order.

  6. Broadband wide-angle polarization converter for LCD backlight.

    Science.gov (United States)

    Tsai, Chang-Ching; Wu, Shin-Tson

    2008-05-20

    A novel polarization converter using reflective metallic gratings and a polarization beam splitter is introduced for LCD backlight illumination. These two optical elements form a polarization rotation resonator. Broadband and high optical efficiency of polarization conversion in the visible region is achieved through the resonance of the refracted light and the surface plasmon wave in metallic surface-relief gratings. For wide-angle illumination, the conversion efficiency with arbitrary incident angle is studied. This device can convert unpolarized light to linear polarization with over 85% efficiency. PMID:18493296

  7. Improved Interference Suppression Algorithm Against Broadband BPSK Interference

    Institute of Scientific and Technical Information of China (English)

    AN Jian-ping; XIA Cai-jie; WANG Ai-hua

    2008-01-01

    An improved polar exciser (IMPE) interference suppression method against broadband constant envelope binary phase shift keying (BPSK) interference is proposed. The disadvantage of traditional polar exciser (PE) is the performance degradation when the power of interference is low, i.e., the threshold effect. The proposed improved PE (IMPE) algorithm can overcome the threshold effect of PE by introducing compression gain (CG) metric, which forces PE suppressor active only at larger jammer-to-signal ratio (JSR) and switch to matched filter (MF) at lower JSR. Theoretical analysis and numerical simulations show the exactness of CG as a switching metric and the validity of the IMPE algorithm.

  8. Design of broadband omnidirectional antireflection coatings using ant colony algorithm.

    Science.gov (United States)

    Guo, X; Zhou, H Y; Guo, S; Luan, X X; Cui, W K; Ma, Y F; Shi, L

    2014-06-30

    Optimization method which is based on the ant colony algorithm (ACA) is described to optimize antireflection (AR) coating system with broadband omnidirectional characteristics for silicon solar cells incorporated with the solar spectrum (AM1.5 radiation). It's the first time to use ACA method for optimizing the AR coating system. In this paper, for the wavelength range from 400 nm to 1100 nm, the optimized three-layer AR coating system could provide an average reflectance of 2.98% for incident angles from Raveθ+ to 80° and 6.56% for incident angles from 0° to 90°. PMID:24978076

  9. Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

    Directory of Open Access Journals (Sweden)

    Jingyan Mo

    2016-01-01

    Full Text Available This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA. The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values are more than 39% and 31.5%, respectively. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.

  10. BaMAP: A Broadband Multimedia Application Platform

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, a broadband multimedia application platform, BaMAP, is introduced. The BaMAP aims to offer content and service providers a good integrated environment for efficient content production, management, delivery and sharing. It supports large-scale hierarchical storage, as well as mechanisms for content distribution and queries from remote nodes. The on-demand service, part of the BaMAP, offers two access interfaces, DVB-C and IP, which allow the platform to run on most of the existing access networks.

  11. Broadband Active Phase Shifter GaAs MMIC

    OpenAIRE

    Duême, Ph.; Dequen, Th.; Funck, R.; Caillon, B.; Guerbeur, G.

    2002-01-01

    A broadband multifunction MMIC, achieving combined amplification and phase shift, has been developed on 2 (3.2 x 4) mm² chips using the UMS PH25 process. The frequency range is as large as characterised by a ratio of Fmax/Fmin = 6. The 5 bit phase shifter section is based on switched "all-pass" cells. The amplification function is realised through active switches consuming less than a total of 40 mA under 3V and providing an overall gain of about +6 dB.

  12. Broadband detection of squeezed vacuum A spectrum of quantum states

    CERN Document Server

    Breitenbach, G; Schiller, S; Mlynek, J; Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1998-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtained. The recorded states show a smooth transition from the squeezed vacuum to a vacuum state. In the time domain we evaluated the first order correlation function of the squeezed output field, showing good agreement with the theory.

  13. Intracavity generation of broadband biphotons in a thin crystal

    Science.gov (United States)

    Katamadze, K. G.; Borshchevskaya, N. A.; Dyakonov, I. V.; Paterova, A. V.; Kulik, S. P.

    2013-04-01

    We propose and realize a method of high intensity generation of broadband biphotons and achieve its value up to 150 THz. The source is based on a thin BBO crystal with a thickness of 100 microns, in which spontaneous parametric down-conversion takes place. To compensate for the intensity decrease of the down-conversion caused by the small thickness of the crystal, it is placed inside the cavity of an Ar+ laser. In general, this experiment relates to the widely discussed problem of two-photon shaping in the frequency and/or angular domain.

  14. Broadband continuum generation in an irregularly multicore microstructured optical fiber

    Institute of Scientific and Technical Information of China (English)

    Peiguang Yan; Qinlin Guo; Guiyao Zhou; Lantian Hou; Yaqing Jia; Hongxin Su; Yigang Li; Lei Ding; Wei Zhang; Kecheng Lü; Tiequn Zhang; Xiaonong Zhu

    2005-01-01

    @@ A broadband continuum generation is reported in a novel multicore microstructured optical fiber (MOF) where irregular air holes are randomly distributed in cladding. By launching ultrashort light pulses from a Ti:sapphire laser into a 190-mm-long fiber of this type, we have observed a group of continua generated from different cores, each with distinct color. 20-dB bandwidth of the broadest continuum is 1260 nm with an average power of 143 mW. The result confirms that the multicore MOF can be fabricated, with different dispersion profiles tailored for specific supercontinuum (SC) generation towards practical applications.

  15. Broadband line imaging with subwavelength resolution using plasmonic waveguides

    OpenAIRE

    Podoliak, N.; Horak, P.; Prangsma, J.C.; Pinkse, P.W.H.

    2015-01-01

    In this paper we design a high-resolution line imaging device allowing for broadband operation at near-infrared wavelengths ranging from 1 ?m to 2 ?m utilizing the advantage of subwavelength light confinement in plasmonic waveguides. The device consists of an array of air-guided plasmonic waveguides in gold with fanned-out geometry. In the main part of the device the separation between waveguides increases gradually from the input towards the output. High resolution is achieved on the input s...

  16. Broadband manipulation of acoustic wavefronts by pentamode metasurface

    International Nuclear Information System (INIS)

    An acoustic metasurface with a sub-wavelength thickness can manipulate acoustic wavefronts freely by the introduction of abrupt phase variation. However, the existence of a narrow bandwidth and a low transmittance limits further applications. Here, we present a broadband and highly transparent acoustic metasurface based on a frequency-independent generalized acoustic Snell's law and pentamode metamaterials. The proposal employs a gradient velocity to redirect refracted waves and pentamode metamaterials to improve impedance matching between the metasurface and the background medium. Excellent wavefront manipulation based on the metasurface is further demonstrated by anomalous refraction, generation of non-diffracting Bessel beam, and sub-wavelength flat focusing

  17. Design and demonstration of broadband thin planar diffractive acoustic lenses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenqi; Xie, Yangbo; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A., E-mail: cummer@ee.duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

    2014-09-08

    We present here two diffractive acoustic lenses with subwavelength thickness, planar profile, and broad operation bandwidth. Tapered labyrinthine unit cells with their inherently broadband effective material properties are exploited in our design. Both the measured and the simulated results are showcased to demonstrate the lensing effect over more than 40% of the central frequency. The focusing of a propagating Gaussian modulated sinusoidal pulse is also demonstrated. This work paves the way for designing diffractive acoustic lenses and more generalized phase engineering diffractive elements with labyrinthine acoustic metamaterials.

  18. Design and demonstration of broadband thin planar diffractive acoustic lenses

    International Nuclear Information System (INIS)

    We present here two diffractive acoustic lenses with subwavelength thickness, planar profile, and broad operation bandwidth. Tapered labyrinthine unit cells with their inherently broadband effective material properties are exploited in our design. Both the measured and the simulated results are showcased to demonstrate the lensing effect over more than 40% of the central frequency. The focusing of a propagating Gaussian modulated sinusoidal pulse is also demonstrated. This work paves the way for designing diffractive acoustic lenses and more generalized phase engineering diffractive elements with labyrinthine acoustic metamaterials.

  19. Contour optimization of a planar broadband dipole using genetic algorithms

    OpenAIRE

    Vasylenko, Dmytro O.; Dubrovka, Fedor F.; Edenhofer, Peter

    2007-01-01

    The application of genetic algorithm (GA) optimization to the design and analysis for planar broadband dipoles of bow-tie type is presented. Primary attention is given to the analysis of the radiating contour profile of the bow-tie antenna. The planar dipole antenna is proposed for UWB communications in the frequency range 3.1-10.6 GHz. A printed design of the proposed antenna is defined for return loss < -10 dB and antenna gain > 2 dB over the whole frequency range.

  20. Broadband manipulation of acoustic wavefronts by pentamode metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Ye; Wei, Qi, E-mail: weiqi@nju.edu.cn; Cheng, Ying [Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Xu, Zheng [School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Liu, Xiaojun, E-mail: liuxiaojun@nju.edu.cn [Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-11-30

    An acoustic metasurface with a sub-wavelength thickness can manipulate acoustic wavefronts freely by the introduction of abrupt phase variation. However, the existence of a narrow bandwidth and a low transmittance limits further applications. Here, we present a broadband and highly transparent acoustic metasurface based on a frequency-independent generalized acoustic Snell's law and pentamode metamaterials. The proposal employs a gradient velocity to redirect refracted waves and pentamode metamaterials to improve impedance matching between the metasurface and the background medium. Excellent wavefront manipulation based on the metasurface is further demonstrated by anomalous refraction, generation of non-diffracting Bessel beam, and sub-wavelength flat focusing.

  1. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.; Zhurbenko, Vitaliy

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...... transmission line. The output power of approximately 600 mW, with an associated gain of 9 dB and PAE greater than 30 percent, is demonstrated in the frequency range from 10 to 1800 MHz....

  2. Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

    KAUST Repository

    Yu, Zongfu

    2012-10-01

    The coupling between free space radiation and optical media critically influences the performance of optical devices. We show that, for any given photonic structure, the sum of the external coupling rates for all its optical modes are subject to an upper bound dictated by the second law of thermodynamics. Such bound limits how efficient light can be coupled to any photonic structure. As one example of application, we use this upper bound to derive the limit of light absorption in broadband solar absorbers. © 2012 American Physical Society.

  3. Cell broadband engine architecture as a DSP platform

    Science.gov (United States)

    Szumski, Karol; Malanowski, Mateusz

    2009-06-01

    The slowing pace of performance improvement in the commonly available processors is a cause of concern amongst many computational scientists. This combined with the ever increasing need for computational power has caused us to turn to alternative architectures in search of performance gains. Two main candidates were the Compute Unified Device Architecture (CUDA) and the Cell Broadband Engine (CELL BE) architecture. This paper focuses on the latter, outlining the architecture and basic programming paradigms, and also contains performance comparison of algorithms currently developed by our team.

  4. Design of Broadband Dispersion Compensating Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Md. Selim Habib

    2012-08-01

    Full Text Available This paper presents a triangular-lattice photonic crystal fiber for broadband dispersion compensation. The finite element method with perfectly matched absorbing layers boundary condition is used to investigate the guiding properties. The designed dispersion compensating fiber shows that it is possible to obtain a larger negative dispersion coefficient of −360 ps/(nm.km at 1.55 μm, better dispersion slope compensation, better compensation ratio in the entire  telecommunication (1460-1640 nm band by using a modest number of design parameters and very simple cladding design.

  5. Distributed Shared Memory for the Cell Broadband Engine (DSMCBE)

    DEFF Research Database (Denmark)

    Larsen, Morten Nørgaard; Skovhede, Kenneth; Vinter, Brian

    2009-01-01

    The CELL-BE processor provides high performance and has been shown to reach a performance close to the theoretical peak, however, the high performance comes at the price of a quite complex programming model. Central to the complexity of the CELL-BE programming model is the need to move data in and...... out of non-coherent local storage blocks for each special processor element. In this paper we present a software library, namely the Distributed Shared Memory for the Cell Broadband Engine (DSMCBE). By using techniques known from distributed shared memory DSMCBE allows programmers to program the CELL...

  6. Compact U-Slotted Antenna for Broadband Radar Applications

    Directory of Open Access Journals (Sweden)

    S. Costanzo

    2013-01-01

    Full Text Available The original U-shaped patch antenna is properly modified in this work to provide a compact and broadband antenna configuration with reduced cross-polar effects, well suitable for modern radar applications. The proposed antenna layout is applied to design, realize, and test two different prototypes working at P-band and C-band, typically adopted for ground-penetrating radar. The experimental results successfully demonstrate a large operating bandwidth between 15% and 20%, a significant reduction of size (about half of the standard configuration, and a low cross-polarization level within the operating frequency range.

  7. Dispersion analysis for broadband guided wave using generalized warblet transform

    Science.gov (United States)

    Yang, Y.; Peng, Z. K.; Zhang, W. M.; Meng, G.; Lang, Z. Q.

    2016-04-01

    Dispersive properties of guided waves (GW), which indicate the group velocity of the wave varies with the frequency, have been widely investigated in many applications. The broadband GW is usually highly dispersive and multimodal, which is a good candidate for time-frequency analysis (TFA). In the time-frequency (TF) domain, the dispersion trajectory of a dispersive single-modal wave, which is a function of frequency, corresponds to its frequency-dependent dispersion law. To analyze such highly dispersive and multimodal broadband guided wave (HDMB-GW) effectively, we proposed a generalized warblet transform (GWT) based TFA method, which comprises the GWT and a mode separation procedure. Advantages of the proposed method include distinguishing and obtaining the dispersion trajectories of highly dispersive and overlapped modes of the HDMB-GW in the TF domain. Comparing with the existing TFA methods, the proposed method is more suitable for the HDMB-GW, especially when the dispersion trajectories of different modes intersect with each other. Both the simulated and experimental analysis on Lamb waves verified the effectiveness of the proposed method in the dispersion analysis for the HDMB-GW.

  8. Broadband, Spectrally Flat, Graphene-based Terahertz Modulators.

    Science.gov (United States)

    Shi, Fenghua; Chen, Yihang; Han, Peng; Tassin, Philippe

    2015-12-01

    Advances in the efficient manipulation of terahertz waves are crucial for the further development of terahertz technology, promising applications in many diverse areas, such as biotechnology and spectroscopy, to name just a few. Due to its exceptional electronic and optical properties, graphene is a good candidate for terahertz electro-absorption modulators. However, graphene-based modulators demonstrated to date are limited in bandwidth due to Fabry-Perot oscillations in the modulators' substrate. Here, a novel method is demonstrated to design electrically controlled graphene-based modulators that can achieve broadband and spectrally flat modulation of terahertz beams. In our design, a graphene layer is sandwiched between a dielectric and a slightly doped substrate on a metal reflector. It is shown that the spectral dependence of the electric field intensity at the graphene layer can be dramatically modified by optimizing the structural parameters of the device. In this way, the electric field intensity can be spectrally flat and even compensate for the dispersion of the graphene conductivity, resulting in almost invariant absorption in a wide frequency range. Modulation depths up to 76% can be achieved within a fractional operational bandwidth of over 55%. It is expected that our modulator designs will enable the use of terahertz technology in applications requiring broadband operation. PMID:26448571

  9. The Future of the Very Broadband Seismic Sensor

    Science.gov (United States)

    Ingate, S. F.; Berger, J.; Collins, J.; Farrell, W.; Fowler, J.; Herrington, P.; Hutt, C. R.; Romanowicz, B.; Sacks, S.; Vernon, F.; Wielandt, E.

    2004-05-01

    Few fundamental advances have been made in seismometers since the introduction of the broadband feedback systems nearly 1/4 century ago. In the intervening period, academic (and to a lesser extent industrial) research and developments on seismographic instrumentation has declined. Today, adequate sensors to meet the scientific requirements are in short supply. This is particularly true of the GSN; the cornerstone of GSN instrumentation is the STS-1 seismometer, which is no longer in production. Further, the pool of trained scientists working on seismographic instrumentation has dwindled to near zero. A 2.5 day workshop was held in Tahoe in March, 2004. Over 40 participants from government, universities, and corporate sectors participated in a mixture of oral, poster and discussion sessions. Through this workshop, the geoscience community interacted with research and development groups involved in sensor technology, material sciences and nanotechnology to assess emerging technologies that have applications in inertial sensors. A goal of this workshop was to consider whether and how such advances might be applied to the design and manufacture of a new-generation, ultra-quiet, mHz - 20 Hz seismic sensors. Key items included an examination of partnerships and technology transfer, new and innovative designs, testing standards and testing facilities, funding strategies and an educational perspective including new University programs. One product of this workshop is the formulation of a plan to revitalize research and development of techniques in broadband seismometry and related seismographic instrumentation.

  10. Low coherence interferometry modelling using combined broadband Gaussian light sources

    Science.gov (United States)

    Jansz, Paul; Wild, Graham; Richardson, Steven; Hinckley, Steven

    2012-02-01

    Using a Low Coherence Interferometry (LCI) model, a comparison of broadband single-Gaussian and multi-Gaussian light sources has been undertaken. For single-Gaussian sources, the axial resolution improved with source bandwidth, confirming the coherence length relation that resolution for single Gaussian sources improves with increasing spectral bandwidth. However, narrow bandwidth light sources resulted in interferograms with overlapping strata peaks and the loss of individual strata information. For multiple-Gaussian sources with the same bandwidth, spectral side lobes increased, reducing A-scan reliability to show accurate layer information without eliminating the side lobes. The simulations show the conditions needed for resolution of strata information for broadband light sources using both single and multiple Gaussian models. The potential to use the model to study LCI and OCT light sources, optical delays and sample structures can better characterise these LCI and OCT elements. Forecasting misinformation in the interferogram, may allow preliminary corrections. With improvements to the LCI-OCT model, more applications are envisaged.

  11. Error and Congestion Resilient Video Streaming over Broadband Wireless

    Directory of Open Access Journals (Sweden)

    Laith Al-Jobouri

    2015-04-01

    Full Text Available In this paper, error resilience is achieved by adaptive, application-layer rateless channel coding, which is used to protect H.264/Advanced Video Coding (AVC codec data-partitioned videos. A packetization strategy is an effective tool to control error rates and, in the paper, source-coded data partitioning serves to allocate smaller packets to more important compressed video data. The scheme for doing this is applied to real-time streaming across a broadband wireless link. The advantages of rateless code rate adaptivity are then demonstrated in the paper. Because the data partitions of a video slice are each assigned to different network packets, in congestion-prone wireless networks the increased number of packets per slice and their size disparity may increase the packet loss rate from buffer overflows. As a form of congestion resilience, this paper recommends packet-size dependent scheduling as a relatively simple way of alleviating the buffer-overflow problem arising from data-partitioned packets. The paper also contributes an analysis of data partitioning and packet sizes as a prelude to considering scheduling regimes. The combination of adaptive channel coding and prioritized packetization for error resilience with packet-size dependent packet scheduling results in a robust streaming scheme specialized for broadband wireless and real-time streaming applications such as video conferencing, video telephony, and telemedicine.

  12. Experimental characterization of broadband electrostatic noise due to plasma compression

    Science.gov (United States)

    Dubois, Ami M.; Thomas, Edward, Jr.; Amatucci, William E.; Ganguli, Gurudas

    2015-11-01

    For a wide variety of laboratory and space plasma environments, theory states that plasmas are unstable to transverse shear flows over a very broad frequency range, where the shear scale length (LE) compared to the ion gyro-radius (ρi) determines the character of the shear-driven instability that may prevail. During active periods in the Earth's magnetosphere, such sheared flows are intensified and broadband electrostatic noise (BEN) is often observed by satellites traversing natural boundary layers. An interpenetrating magnetized plasma configuration is used to create a transverse velocity shear profile similar to that found at natural space plasma boundary layers. The continuous variation and the associated transition of the instability regimes driven by the shear flow mechanism are demonstrated in a single laboratory experiment. For the first time, broadband wave emission, which is correlated to increasing/decreasing stress (i.e., ρi/LE) on a plasma boundary layer, is found under controlled and repeatable conditions. This result provides evidence that the compression/relaxation of a plasma boundary layer leads to a BEN signature and holds out the promise for understanding the cause and effect of the in situ observation of BEN by satellites. This project was supported with funding from the U.S. Department of Energy, the Defense Threat Reduction Agency, and NRL Base Funds.

  13. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    CERN Document Server

    Lin, Lin; Baring, Matthew G; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT Windowed Timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5 - 200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT/GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbo...

  14. Broadband energy harvesting via magnetic coupling between two movable magnets

    International Nuclear Information System (INIS)

    Harvesting energy from ambient mechanical vibrations by the piezoelectric effect has been proposed for powering microelectromechanical systems and replacing batteries that have a finite life span. A conventional piezoelectric energy harvester (PEH) is usually designed as a linear resonator, and suffers from a narrow operating bandwidth. To achieve broadband energy harvesting, in this paper we introduce a concept and describe the realization of a novel nonlinear PEH. The proposed PEH consists of a primary piezoelectric cantilever beam coupled to an auxiliary piezoelectric cantilever beam through two movable magnets. For predicting the nonlinear response from the proposed PEH, lumped parameter models are established for the two beams. Both simulation and experiment reveal that for the primary beam, the introduction of magnetic coupling can expand the operating bandwidth as well as improve the output voltage. For the auxiliary beam, the magnitude of the output voltage is slightly reduced, but additional output is observed at off-resonance frequencies. Therefore, broadband energy harvesting can be obtained from both the primary beam and the auxiliary beam. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. Broadband ultrathin low-profile metamaterial microwave absorber

    Science.gov (United States)

    Sood, Deepak; Tripathi, Chandra Charu

    2016-04-01

    In this paper, a single-layer broadband low-profile ultrathin metamaterial microwave absorber is proposed for wide angle of incidence. The proposed absorber provides triple-band absorption under normal incidence of electromagnetic wave with two peaks lying in X-band and one in Ku-band. The unit cell is designed by using parametric optimization in such a way that the three peaks merge together to give broadband absorption. The absorber exhibits full width at half maxima bandwidth (FWHM) of 7.75 GHz from 7.55 to 15.30 GHz for wide angle of incidence up to 60° for both TE and TM polarizations. The mechanism of absorption of the absorber has been analyzed by field and surface current distributions. The proposed absorber has been fabricated and experimentally tested for different angles of incidence and polarization of the incident wave. The absorber is low profile with unit cell dimension of the order of 0.168 λ 0, and it is ultrathin with a thickness of ~ λ 0/17 at the center frequency of 11.43 GHz corresponding to the FWHM absorption bandwidth. This proposed absorber can be used for many potential applications such as stealth technology, cloaking and in antenna systems.

  16. Exoplanet detection and characterization via parallel broadband nulling coronagraphy

    Science.gov (United States)

    Hicks, Brian A.

    2016-01-01

    The contrast and angular resolution required to directly image and characterize mature exoplanetary systems place stringent requirements on the space-based telescopes and starlight suppression systems needed to study spatial distributions of debris disks, exozodiacal dust, and individual planets at multiple epochs in their orbits. A nulling interferometer (nuller) is a coronagraphic suppression system that can be used with all telescope types, including those with obscured and segmented apertures envisioned for upcoming and future observatories. One of the challenges for detection and characterization of exoplanetary signals is achieving high contrast with broad spectral coverage. This work presents design concepts for broadband nulling over four parallel ˜20% bandpasses spanning the visible spectrum. Contrast-limiting effects of stellar angular extent, residual chromaticity of broadband phase shifters, and aperture diffraction are considered to reach simultaneous ≲2×10-8 contrast over separations spanning 0.2 to 0.9 arc sec for a 2.4-m telescope observing a Sun-like star at 10 pc. With added dark hole wavefront control and postprocessing point spread function subtraction techniques to further reduce scattered starlight, such a system could be capable of detecting the very the nearest Earth-like exoplanets and spectral characterization of several nearby extrasolar gas giants.

  17. Mirror-based broadband scanner with minimized aberration

    Science.gov (United States)

    Yu, Jiun-Yann; Tzeng, Yu-Yi; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

    2009-02-01

    To obtain specific biochemical information in optical scanning microscopy, labeling technique is routinely required. Instead of the complex and invasive sample preparation procedures, incorporating spectral acquisition, which commonly requires a broadband light source, provides another mechanism to enhance molecular contrast. But most current optical scanning system is lens-based and thus the spectral bandwidth is limited to several hundred nanometers due to anti-reflection coating and chromatic aberration. The spectral range of interest in biological research covers ultraviolet to infrared. For example, the absorption peak of water falls around 3 μm, while most proteins exhibit absorption in the UV-visible regime. For imaging purpose, the transmission window of skin and cerebral tissues fall around 1300 and 1800 nm, respectively. Therefore, to extend the spectral bandwidth of an optical scanning system from visible to mid-infrared, we propose a system composed of metallic coated mirrors. A common issue in such a mirror-based system is aberrations induced by oblique incidence. We propose to compensate astigmatism by exchanging the sagittal and tangential planes of the converging spherical mirrors in the scanning system. With the aid of an optical design software, we build a diffraction-limited broadband scanning system with wavefront flatness better than λ/4 at focal plane. Combined with a mirror-based objective this microscopic system will exhibit full spectral capability and will be useful in microscopic imaging and therapeutic applications.

  18. Further Development and Assessment of a Broadband Liner Optimization Process

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.

    2016-01-01

    The utilization of advanced fan designs (including higher bypass ratios) and shorter engine nacelles has highlighted a need for increased fan noise reduction over a broader frequency range. Thus, improved broadband liner designs must account for these constraints and, where applicable, take advantage of advanced manufacturing techniques that have opened new possibilities for novel configurations. This work focuses on the use of an established broadband acoustic liner optimization process to design a variable-depth, multi-degree of freedom liner for a high speed fan. Specifically, in-duct attenuation predictions with a statistical source model are used to obtain optimum impedance spectra over the conditions of interest. The predicted optimum impedance information is then used with acoustic liner modeling tools to design a liner aimed at producing impedance spectra that most closely match the predicted optimum values. The multi-degree of freedom design is carried through design, fabrication, and testing. In-duct attenuation predictions compare well with measured data and the multi-degree of freedom liner is shown to outperform a more conventional liner over a range of flow conditions. These promising results provide further confidence in the design tool, as well as the enhancements made to the overall design process.

  19. Efficient Implementation of a Symbol Timing Estimator for Broadband PLC

    Directory of Open Access Journals (Sweden)

    Francisco Nombela

    2015-08-01

    Full Text Available Broadband Power Line Communications (PLC have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA.

  20. The Evolution of the Policy Objectives of South Korea's Broadband Convergence Network from 2004 to 2007

    Science.gov (United States)

    Menon, Siddhartha

    2011-01-01

    The purpose of this study is to explore the South Korean government's policy objectives for the Broadband Convergence Network (BcN) between 2004 and 2007. The BcN is envisioned as conduit for broadband content and applications. This paper uses generativity as a conceptual framework to determine whether the objectives for the BcN, based on a…

  1. Exploring Geographic Disparities in Broadband Access and Use in Rural Southern Illinois: Who's Being Left behind?

    Science.gov (United States)

    Oyana, Tonny J.

    2011-01-01

    Recent literature about broadband telecommunications reveals two major areas that are not only globally gaining prominence, but are also demanding urgent attention from a research perspective. One of the key areas is related to the need to spatially evaluate the availability and deployment of broadband services, especially among urban versus rural…

  2. Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation.

    Science.gov (United States)

    Hermann, Peter; Hoehl, Arne; Patoka, Piotr; Huth, Florian; Rühl, Eckart; Ulm, Gerhard

    2013-02-11

    We demonstrate scanning near-field optical microscopy with a spatial resolution below 100 nm by using low intensity broadband synchrotron radiation in the IR regime. The use of such a broadband radiation source opens up the possibility to perform nano-Fourier-transform infrared spectroscopy over a wide spectral range. PMID:23481749

  3. Continuous Vernier filtering of an optical frequency comb for broadband cavity-enhanced molecular spectroscopy

    CERN Document Server

    Rutkowski, Lucile

    2016-01-01

    We have recently introduced the Vernier-based Direct Frequency Comb Cavity-Enhanced Spectroscopy technique and we present the corresponding formalism for quantitative broadband spectroscopy. We achieve high sensitivity and broadband performance by acquiring spectra covering more than 2000 cm$^{-1}$ around 12600 cm$^{-1}$ (800 nm), resolving the 3$\

  4. The Broadband Quandary for Rural America. The Main Street Economist: Commentary on the Rural Economy.

    Science.gov (United States)

    Staihr, Brian

    High speed data services known as broadband have the potential to make rural areas less isolated and improve the rural quality of life, but physical barriers, sparse population density, and few markets present significant obstacles to their deployment in rural areas. Broadband applications such as e-commerce, distance education, and telemedicine…

  5. 47 CFR 90.18 - Public Safety 700 MHz Nationwide Broadband Network.

    Science.gov (United States)

    2010-10-01

    ... Network. 90.18 Section 90.18 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... 700 MHz Nationwide Broadband Network. The 763-768/793-798 MHz band is dedicated to a broadband public..., pursuant to a Network Sharing Agreement and such other agreements as the Commission may require....

  6. Design of broadband transmission quarter-wave plates for polarization control of isolated attosecond pulses

    International Nuclear Information System (INIS)

    Using a standard Levenberg–Marquardt algorithm, broadband quarter-wave plates (QWPs) with bandwidth from 3 to 18 eV in the extreme ultraviolet (EUV) region were designed using aperiodic Mo/Si multilayers. By analyzing the design results of the Mo/Si multiayers with different bilayer numbers, we found that a Mo/Si multilayer with more bilayers can achieve broader phase control, but suffers from lower total throughput and a degree of circular polarization. In addition, the pulse broadenings caused by the group delay dispersions of the designed broadband QWPs were studied, and their layer distributions were investigated. The oscillating distribution of bilayer thickness in optimized multilayers was observed, which is considered to be the reason for forming the broadband phase control. Such broadband QWPs can be applied to generate a circularly polarized broadband EUV source, such as isolated attosecond pulse, directly from a linearly polarized source. (paper)

  7. Autonomous, continuously recording broadband seismic stations at high-latitude

    Science.gov (United States)

    Beaudoin, B.; Parker, T.; Bonnett, B.; Tytgat, G.; Anderson, K.; Fowler, J.

    2009-04-01

    IRIS PASSCAL is in the third year of an NSF funded development and acquisition effort to establish a pool of cold-hardened seismic stations specifically for high-latitude broadband deployments. We have two complete years of field trials and have successfully recorded continuous seismic data during both years with data recovery rates of ~90%. Our design is premised on a 2W autonomous system recording to local media, capable of lasting two years without service. The system is composed of four new design elements: a heavily insulated station enclosure; a state-of-health (SOH) Iridium modem; a light weight, easily deployed solar panel mount; and a power system that includes power switching between primary (Lithium Thionyl Chloride) and secondary batteries. The station enclosures have proved most critical in keeping our data acquisition systems operating within manufacturer specifications and primary batteries within a 50-70% efficiency range. Enclosures with 2.5cm-thick vacuum panels and 5cm of foam insulation have kept interior enclosure temperatures 25-30°C above background (typically below -50°C). This austral summer we are deploying version three of our enclosures. Significant changes in the design include thicker vacuum panels (5cm), more robust construction, and simplified cable routing. An important aspect of our station design is easy installation and minimal weight. To simplify installation our station enclosures are packed with datalogger, SOH communications and batteries in the lab or base camp, so that access to the internal components is not necessary at the remote site. Bulkhead connectors allow a user to fully interact with the system without ever having to open the enclosure. Solar panel mounts are also fully constructed prior to deployment. Once on site, digging two large holes (one for the enclosure and one for the broadband seismometer) and constructing the site takes roughly 2 hours. A station designed to record continuously for 12-14 months is

  8. Broadband metacoaxial nanoantenna for metasurface and sensing applications.

    Science.gov (United States)

    Smolyaninov, Alexei; Pang, Lin; Freeman, Lindsay; Abashin, Maxim; Fainman, Yeshaiahu

    2014-09-22

    We introduce a metacoaxial nanoantenna (MN) that super-localizes the incident electromagnetic field to "hotspots" with a top-down area of 2 nm(2), a local field enhancement of ~200-400, and a field localization with a very large spectral range from the visible to the infrared range that has a spectral bandwidth ≥ 900 nm. Not only is this nanoantenna extremely broadband with ultra-high localization, it also shows significant improvements over traditional nanoantenna designs, as the hotspots are re-configurable by breaking the circular symmetry which enables the ability to tailor the polarization response. These attributes offer significant improvements over traditional nanoantennas as building blocks for metasurfaces and enhanced biodetection that we demonstrate in this work. PMID:25321747

  9. Broadband non-reciprocal transmission of sound with invariant frequency

    CERN Document Server

    Gu, Zhong-ming; Liang, Bin; Zou, Xin-ye; Cheng, Jian-chun

    2015-01-01

    The emergence of "acoustic diode" (AD) capable of rectifying acoustic wave like electrical diodes do to electricity has been believed to be able to offer unconventional manipulation on sound, e.g., to isolate the wrong-way reflection, and therefore have great potential in various important scenarios such as medical ultrasound applications. However, the existing ADs have always been suffering from the problem that the transmitted wave must have either doubled frequency or deviated direction, lacking the most crucial features for achieving such expectations in practice. Here we design and experimentally demonstrate a broadband yet compact non-reciprocal device with hitherto inaccessible functionality of maintaining the original frequency and high forward transmission while virtually blocking the backscattered wave, which is close to what a perfect AD is expected to provide and is promising to play the essential role in realistic acoustic systems like electric diodes do in electrical circuits. Such an extreme ab...

  10. Calculated secondary yields for proton broadband using DECAY TURTLE

    International Nuclear Information System (INIS)

    The calculations for the yields were done by Al Sondgeroth and Anthony Malensek. The authors used the DECAY deck called PBSEC E.DAT from the CMS DECKS library. After obtaining the run modes and calibration modes from the liaison physicist, they made individual decay runs, using DECAY TURTLE from the CMS libraries and a production spectrum subroutine which was modified by Anthony, for each particle and decay mode for all particle types coming out of the target box. Results were weighted according to branching ratios for particles with more than one decay mode. The production spectra were produced assuming beryllium as the target. The optional deuterium target available to broadband will produce slightly higher yields. It should be noted that they did not include pion yields from klong decays because they could not simulate three body decays. Pions from klongs would add a very small fraction to the total yield

  11. Invited Article: Broadband highly efficient dielectric metadevices for polarization control

    Science.gov (United States)

    Kruk, Sergey; Hopkins, Ben; Kravchenko, Ivan I.; Miroshnichenko, Andrey; Neshev, Dragomir N.; Kivshar, Yuri S.

    2016-06-01

    Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: a narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle, with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms, to achieve destructive interference in reflection over a large spectral bandwidth. By employing this novel concept, we demonstrate reflectionless (˜90% transmission) half-wave plates, quarter-wave plates, and vector beam q-plates that can operate across multiple telecom bands with ˜99% polarization conversion efficiency.

  12. Efficient and broadband polarization conversion with the coupled metasurfaces.

    Science.gov (United States)

    Huang, Cheng-ping

    2015-12-14

    Coupled metasurfaces may refer to a composite plasmonic structure, which consists of multilayered but usually different metasurfaces. A pair of orthogonal plasmonic polarizers, which represents one of such systems, can induce a transmission of light and 90-degree polarization rotation. We explored the effect systematically and found that such effect may be highly efficient and broadband in the near-infrared region. By combining the low-loss metal (silver), the longer operating wavelength, and a work style using propagating waveguide mode, conversion efficiency more than 80% has been suggested near the telecom wavelength. We also suggested that, by overlapping the internal surface-plasmon (2, 0) and (1, 1) modes, an efficient and wideband polarization rotation can be realized. The maximal efficiency is 83% around the wavelength 1340 nm, and the working bandwidth reaches 300 nm. Similar effect has also been revealed in the THz band. The results are useful for constructing compact and high-performance polarization rotators. PMID:26698992

  13. The Australia Telescope Compact Array Broadband Backend (CABB)

    CERN Document Server

    Wilson, Warwick E; Axtens, P; Brown, A; Davis, E; Hampson, G; Leach, M; Roberts, P; Saunders, S; Koribalski, B S; Caswell, J L; Lenc, E; Stevens, J; Voronkov, M A; Wieringa, M H; Brooks, K; Edwards, P G; Ekers, R D; Emonts, B; Hindson, L; Johnston, S; Maddison, S T; Mahony, E K; Malu, S S; Massardi, M; Mao, M Y; McConnell, D; Norris, R P; Schnitzeler, D; Subrahmanyan, R; Urquhart, J S; Thompson, M A; Wark, R M

    2011-01-01

    Here we describe the Compact Array Broadband Backend (CABB) and present first results obtained with the upgraded Australia Telescope Compact Array (ATCA). The 16-fold increase in observing bandwidth, from 2 x 128 MHz to 2 x 2048 MHz, high bit sampling, and addition of 16 zoom windows (each divided into a further 2048 channels) provide major improvements for all ATCA observations. The benefits of the new system are: (1) hugely increased radio continuum and polarization sensitivity as well as image fidelity, (2) substantially improved capability to search for and map emission and absorption lines over large velocity ranges, (3) simultaneous multi-line and continuum observations, (4) increased sensitivity, survey speed and dynamic range due to high-bit sampling, and (5) high velocity resolution, while maintaining full polarization output. The new CABB system encourages all observers to make use of both spectral line and continuum data to achieve their full potential. Given the dramatic increase of the ATCA capab...

  14. Frequency-shifted feedback amplifier for broadband laser cooling

    Science.gov (United States)

    Lim, Michael; van Kooy, Alexander; Yanakas, Michael

    2014-03-01

    We have developed a compact, all-solid state laser amplifier for generating asymmetric sidebands with controlled number and spacing of optical frequencies. The gain element is a tapered semiconductor amplifier, used in conjunction with an acousto-optic modulator that generates red-detuned feedback frequencies. This results in asymmetric sidebands that are all lower in optical frequency than the narrowband seed laser frequency. The output laser spectrum has a well-defined edge (the input laser frequency) and multiple sidebands whose number, frequency spacing, and power are fully controlled by the seed laser characteristics and a single radio frequency input. The number of sidebands can be varied in a controlled way, and the output optical power is variable up to the Watt level of the amplifier chip. The system will be used for broadband laser cooling.

  15. Broadband infrared vibrational nano-spectroscopy using thermal blackbody radiation.

    Science.gov (United States)

    O'Callahan, Brian T; Lewis, William E; Möbius, Silke; Stanley, Jared C; Muller, Eric A; Raschke, Markus B

    2015-12-14

    Infrared vibrational nano-spectroscopy based on scattering scanning near-field optical microscopy (s-SNOM) provides intrinsic chemical specificity with nanometer spatial resolution. Here we use incoherent infrared radiation from a 1400 K thermal blackbody emitter for broadband infrared (IR) nano-spectroscopy. With optimized interferometric heterodyne signal amplification we achieve few-monolayer sensitivity in phonon polariton spectroscopy and attomolar molecular vibrational spectroscopy. Near-field localization and nanoscale spatial resolution is demonstrated in imaging flakes of hexagonal boron nitride (hBN) and determination of its phonon polariton dispersion relation. The signal-to-noise ratio calculations and analysis for different samples and illumination sources provide a reference for irradiance requirements and the attainable near-field signal levels in s-SNOM in general. The use of a thermal emitter as an IR source thus opens s-SNOM for routine chemical FTIR nano-spectroscopy. PMID:26698997

  16. Broadband non-reciprocal transmission of sound with invariant frequency

    Science.gov (United States)

    Gu, Zhong-Ming; Hu, Jie; Liang, Bin; Zou, Xin-Ye; Cheng, Jian-Chun

    2016-01-01

    We design and experimentally demonstrate a broadband yet compact acoustic diode (AD) by using an acoustic nonlinear material and a pair of gain and lossy materials. Due to the capabilities of maintaining the original frequency and high forward transmission while blocking backscattered wave, our design is closer to the desired features of a perfect AD and is promising to play the essential diode-like role in realistic acoustic systems, such as ultrasound imaging, noise control and nondestructive testing. Furthermore, our design enables improving the sensitivity and the robustness of device simultaneously by tailoring an individual structural parameter. We envision our design will take a significant step towards the realization of applicable acoustic one-way devices, and inspire the research of non-reciprocal wave manipulation in other fields.

  17. Self-Organizing OFDMA System for Broadband Communication

    Science.gov (United States)

    Roy, Aloke (Inventor); Anandappan, Thanga (Inventor); Malve, Sharath Babu (Inventor)

    2016-01-01

    Systems and methods for a self-organizing OFDMA system for broadband communication are provided. In certain embodiments a communication node for a self organizing network comprises a communication interface configured to transmit data to and receive data from a plurality of nodes; and a processing unit configured to execute computer readable instructions. Further, computer readable instructions direct the processing unit to identify a sub-region within a cell, wherein the communication node is located in the sub-region; and transmit at least one data frame, wherein the data from the communication node is transmitted at a particular time and frequency as defined within the at least one data frame, where the time and frequency are associated with the sub-region.

  18. Omnidirectional broadband insulating device for flexural waves in thin plates

    CERN Document Server

    Climente, Alfonso; Sánchez-Dehesa, José

    2013-01-01

    This work presents a gradient index device for insulating from vibrations a circular area of a thin plate. The gradient of the refractive index is achieved by locally changing the thickness of the plate, exploiting in this way the thickness-dependence of the dispersion relation of flexural waves in thin plates. A well-like thickness profile in an annular region of the plate is used to mimic the combination of an attractive and repulsive potentials, focusing waves at its bottom and dissipating them by means of a properly designed absorptive layer placed on top of the plate. The central area is therefore isolated from vibrations while they are dissipated at the bottom of the well. Simulations have been done using the multilayer multiple scattering method and the results prove their broadband efficiency and omnidirectional properties.

  19. Nanoscale broadband transmission lines for spin qubit control

    Science.gov (United States)

    Dehollain, J. P.; Pla, J. J.; Siew, E.; Tan, K. Y.; Dzurak, A. S.; Morello, A.

    2013-01-01

    The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.

  20. Conversion of broadband to narrowband thermal emission through energy recycling

    Science.gov (United States)

    de Zoysa, Menaka; Asano, Takashi; Mochizuki, Keita; Oskooi, Ardavan; Inoue, Takuya; Noda, Susumu

    2012-08-01

    Converting from a broadband to a narrowband thermal emission spectrum with minimal loss of energy is important in the creation of efficient environmental sensors and biosensors as well as thermo-photovoltaic power generation systems. Here, we demonstrate such thermal emission control by manipulating photonic modes with photonic crystals as well as material absorption with quantum-well intersubband transitions. We show that the emission peak intensity for our device can be more than four times greater than that of a blackbody sample under the same input power and thermal management conditions due to an increase in the temperature compared to the blackbody reference, and the emission bandwidth and angular spread are narrowed by a factor of 30 and 8, respectively. These results indicate that the energy saved by thermal emission control can be recycled and concentrated to enhance the narrow peak emission intensity.

  1. Broad-band characteristics of circular button pickups

    International Nuclear Information System (INIS)

    A broad-band.theory of the circular button pickup is presented. Expressions for the longitudinal and transverse transfer impedance of a pair of such pickups are derived in the frequency domain. The broad-band expressions are shown to reduce to the standard electrostatic transfer functions for wavelengths large compared to the button diameter. The theory is shown to be in reasonable agreement with measurements performed on standard LEP button electrodes. In particular, the theory explains a resonance in the response of the LEP buttons which made them unsuitable, in standard form, for their intended application as pickups in the LBL Advanced Light Source feedback system. The buttons were modified to suppress the resonance and subsequently incorporated into the feedback system

  2. Best-basis analysis of broadband tremor signals

    Directory of Open Access Journals (Sweden)

    P. Steffen

    1999-06-01

    Full Text Available Active volcanoes usually generate highly non-stationary broadband tremor signals. Short-time shock events with a frequency content of several decades are superimposed on a stationary narrow band continuous tremor. Tremor signals of this type can be observed in the near field of many active volcanoes. In this paper we will demonstrate the analysis of such signals using a specific tremor signal of Mt. Stromboli (Sicily. We used the Best-Basis Algorithm (BBA in order to compute a spectrogram which is adapted to signal properties on highly different scales. It turns out that the BBA can reveal better fitting properties of the tremor in the time-frequency plane compared to standard methods like Short-Time Fourier Transformation (STFT. Moreover, this very effective algorithm can be used for real time monitoring in the time-frequency plane, for data compression or for de-noising of the tremor signals.

  3. Low-voltage broadband hybrid plasmonic-vanadium dioxide switches

    CERN Document Server

    Joushaghani, Arash; Paradis, Suzanne; Alain, David; Aitchison, J Stewart; Poon, Joyce K S

    2012-01-01

    Surface plasmon polaritons can substantially reduce the sizes of optical devices, since they can concentrate light to (sub)wavelength scales. However, (sub)wavelength-scale electro-optic plasmonic switches or modulators with high efficiency, low insertion loss, and high extinction ratios remain a challenge due to their small active volumes. Here, we use the insulator-metal phase transition of a correlated-electron material, vanadium dioxide, to overcome this limitation and demonstrate compact, broadband, and efficient plasmonic switches with integrated electrical control. The devices are micron-scale in length and operate near a wavelength of 1550 nm. The switching bandwidths exceed 100 nm and applied voltages of only 400 mV are sufficient to attain extinction ratios in excess of 20 dB. Our results illustrate the potential of using phase transition materials for highly efficient and ultra-compact plasmonic switches and modulators.

  4. Mission-Critical Mobile Broadband Communications in Open Pit Mines

    DEFF Research Database (Denmark)

    Uzeda Garcia, Luis Guilherme; Portela Lopes de Almeida, Erika; Barbosa, Viviane S. B.;

    2016-01-01

    that need to be met by the wireless network. This article introduces fundamental concepts behind open-pit mining and discusses why this ever changing environment coupled with strict industrial reliability requirements pose unique challenges to traditional broadband network planning and optimization......The need for continuous safety improvements and increased operational efficiency is driving the mining industry through a transition towards automated operations. From a communications perspective, this transition introduces a new set of high-bandwidth business- and mission-critical applications...... techniques. On the other hand, unlike unpredictable disaster scenarios, mining is a carefully planned activity. Taking advantage of this predictability element, we propose a framework that integrates mine and network planning so that continuous and automated adaptation of the network becomes possible...

  5. Broadband plasmonic response of self-organized aluminium nanowire arrays

    International Nuclear Information System (INIS)

    We investigated the plasmonic response of arrays of Al nanowires fabricated in high-vacuum and embedded within a transparent protective medium. The nanostructures exhibited a strongly-birefringent plasmonic response which, depending on the mutual orientation of the incident-field polarization and the nanowire axis, allowed the plasmon resonance to span the whole spectral range from the visible to the deep-ultraviolet regime. Comparing the experimental data with theoretical calculations allowed to rationalize the optical response in terms of non-ideal nanowire morphologies arising from the bottom-up character of the nanofabrication method. The broadband plasmonic response suggests the potential application of these systems in plasmon-enhanced photovoltaics, exploiting the great advantage of the low-cost of aluminium. (paper)

  6. Broadband RF front-end using microwave photonics filter.

    Science.gov (United States)

    Wang, Jingjing; Chen, Minghua; Liang, Yunhua; Chen, Hongwei; Yang, Sigang; Xie, Shizhong

    2015-01-26

    We propose and demonstrate a novel RF front-end with broadened processing bandwidth, where a tunable microwave photonic filter based on optical frequency comb (OFC) is incorporated to accomplish simultaneous down-conversion and filtering. By designing additional phase shaping and time delay controlling, the frequency tunability of the system could be enhanced. More importantly, the beating interferences generated from broadband RF input could also be suppressed, which help to break the limitation on the processing bandwidth. In our experiments, a photonics RF receiver front-end for RF input with wide bandwidth of almost 20 GHz was realized using 10-GHz-space OFC, where the center frequency of the pass band signals could be tuned continuously. PMID:25835844

  7. Broadband-antireflective hybrid nanopillar array for photovoltaic application

    International Nuclear Information System (INIS)

    Subwavelength structures such as nanopillars, nanoholes, and nanodomes have recently attracted considerable attention as antireflective structures for solar cells. Recent studies on the optical property of nanopillar array revealed that the reflection minimum is related to the diameter, the pitch, and the height of nanopillars. Here, we investigate the “hybrid” nanopillar array, which is composed of different diameters of nanopillars. Finite differential time domain simulations revealed that the photogeneration in a hybrid nanopillar array is spatially heterogeneous: carriers are generated mainly in the narrower pillars for short-wavelength incident light and in the thicker pillars for long-wavelength light, respectively. Hybrid silicon nanopillar arrays fabricated by using electron beam lithography and dry etching show excellent broadband antireflection property. Hybrid nanopillar array is thus highly promising for next-generation antireflection for photovoltaic applications

  8. Guidelines for Standardized Testing of Broadband Seismometers and Accelerometers

    Science.gov (United States)

    Hutt, Charles R.; Evans, John R.; Followill, Fred; Nigbor, Robert L.; Wielandt, Erhard

    2010-01-01

    Testing and specification of seismic and earthquake-engineering sensors and recorders has been marked by significant variations in procedures and selected parameters. These variations cause difficulty in comparing such specifications and test results. In July 1989, and again in May 2005, the U.S. Geological Survey hosted international pub-lic/private workshops with the goal of defining widely accepted guidelines for the testing of seismological inertial sensors, seismometers, and accelerometers. The Proceedings of the 2005 workshop have been published and include as appendix 6 the report of the 1989 workshop. This document represents a collation and rationalization of a single set of formal guidelines for testing and specifying broadband seismometers and accelerometers.

  9. Short-term Variability of Extinction by Broadband Stellar Photometry

    Energy Technology Data Exchange (ETDEWEB)

    Musat, I.C.; Ellingson, R.G.

    2005-03-18

    Aerosol optical depth variation over short-term time intervals is determined from broadband observations of stars with a whole sky imager. The main difficulty in such measurements consists of accurately separating the star flux value from the non-stellar diffuse skylight. Using correction method to overcome this difficulty, the monochromatic extinction at the ground due to aerosols is extracted from heterochromatic measurements. A form of closure is achieved by comparison with simultaneous or temporally close measurements with other instruments, and the total error of the method, as a combination of random error of measurements and systematic error of calibration and model, is assessed as being between 2.6 and 3% rms.

  10. The Broadband Spectral Energy Distribution of the MOJAVE Sample

    CERN Document Server

    Chang, C S; Kadler, M; Aller, M F; Aller, H D; Angelakis, E; Fuhrmann, L; Nestoras, I; Ungerechts, H

    2010-01-01

    We are constructing the broadband SED catalog of the MOJAVE sample from the radio to the gamma-ray band using MOJAVE, Swift UVOT/XRT/BAT, and Fermi/LAT data, in order to understand the emission mechanism of extragalactic outflows and to investigate the site of high-energy emission in AGN. Since the launch of Fermi gamma-ray Space Telescope in August 2008, two thirds of the MOJAVE sources have been detected by Fermi/LAT. Combining the results of high-resolution VLBI, X-ray, and gamma-ray observations of the jet-dominated AGN sample, we want to pin down the origin of high-energy emission in relativistic jets. Here we present our overall project and preliminary results for 6 selected sources.

  11. Broadband communications in medicine - Race-Project Telemed

    International Nuclear Information System (INIS)

    State-of-the-art imaging techniques, in conjunction with recently developed computer-assisted diagnostic procedures in medicine, have permitted digital production and retrieval systems for radiographs to become part of the standard equipment of hospitals. The vast range of data provided by those pictures and low transmission rates of long-distance networks have, however, so far created a roadblock to regular exchanges of electronic images between the individual medical institutions. Race-Project Telemed, which offers the possibility of broadband communications, is now paving the way for physicians all over Europe to cooperate more effectively (by means of on-the-spot long-distance consultation and diagnosis, reference data bases for radiographs, etc.). (HP)

  12. Broadband Continuous Wave Quantum Cascade laser beatnote characterization

    International Nuclear Information System (INIS)

    Full text: Quantum cascade lasers (QCLs) operated in continuous wave tend to become multimode above a certain value of the threshold current. There is great interest in understanding this multimode behavior in QCLs, since it is of key importance for technology to master this regime for various applications. We present a study of the beatnote, measured using a quantum well infrared photodetector at the round trip frequency of the laser, of a broadband continuous wave QCL. The laser emits radiation over 200 cm-1 with an output power of 78 mW at -200C at a center wavelength of 7 μm. We record an interferogram of the beatnote through an FTIR. This gives us information on the relative phases between the laser modes as well as the spectral composition of the beatnote. (author)

  13. Maskless fabrication of broadband antireflection nanostructures on glass surfaces

    Science.gov (United States)

    Tamayo R, E. E.; Hoshii, T.; Tamaki, R.; Watanabe, K.; Sugiyama, M.; Okada, Y.; Miyano, K.

    2016-06-01

    In order to reduce reflection losses at the surface of glass optical components, we have developed a plasma-etching fabrication method in which a CaF2 mask is self-assembled on the glass surface, generating nanostructures of around 100 nm in size, fabricated with an approximate etching rate of 10 nm per minute, and with controllable height, depending on the process time. By treating glasses with different compositions, it was found that the nanostructures can be successfully fabricated in a glass composed mainly of SiO2, but with 10% CaO content. In addition to the high aspect ratio and tapered geometry of the nanostructures, through cross-section composition analysis, graded Si and O compositions were also found within the nanostructures. The combined contribution of the geometrical and graded composition effects resulted in broadband 96% and over 99% transmittance on one-side and both-side treated glass substrates, respectively.

  14. Integrated Broadband Bowtie Antenna on Transparent Silica Substrate

    CERN Document Server

    Zhang, Xingyu; Wang, Shiyi; Subbaraman, Harish; Pan, Zeyu; Zhan, Qiwen; Chen, Ray T

    2016-01-01

    The bowtie antenna is a topic of growing interest in recent years. In this paper, we design, fabricate, and characterize a modified gold bowtie antenna integrated on a transparent silica substrate. The bowtie antenna is designed with broad RF bandwidth to cover the X-band in the electromagnetic spectrum. We numerically investigate the antenna characteristics, specifically its resonant frequency and enhancement factor. Our designed bowtie antenna provides a strong broadband electric field enhancement in its feed gap. Taking advantage of the low-k silica substrate, high enhancement factor can be achieved without the unwanted reflection and scattering from the backside silicon handle which is the issue of using an SOI substrate. We simulate the dependence of resonance frequency on bowtie geometry, and verify the simulation results through experimental investigation, by fabricating different sets of bowtie antennas on silica substrates and then measuring their resonance frequencies. In addition, the far-field rad...

  15. Broadband ultrasonic spectroscopy for the characterization of viscoelastic materials.

    Science.gov (United States)

    Aksoy, Hüseyin Gökmen

    2016-04-01

    In this study, non-destructive experimental method based on acoustic through transmission technique along with broadband spectroscopy is proposed in order to determine the linear viscoelastic material properties in 20-400kHz range. Material properties such as phase velocity and attenuation coefficient of longitudinal and shear waves are measured. Diffraction correction developed for focused transducers is used to eliminate the spreading error due to the spherical wave generated by the hydrophone which is used as a transmitter. Method is validated on polymethyl methacrylate (PMMA). Both longitudinal wave velocity, shear wave velocity and attenuation coefficient of longitudinal wave of PMMA are in agreement with the previously reported values which are given in the literature. Attenuation coefficient of shear wave in PMMA is measured successfully and in agreement with the theoretical predictions. Longitudinal wave velocity and corresponding attenuation coefficient of gelatine gel are also measured. PMID:26859428

  16. Optical technique for broadband microwave absorption spectroscopy in aqueous media

    International Nuclear Information System (INIS)

    Precise measurements of microwave absorption over a large range of frequencies in aqueous media are difficult to obtain and can result in conflicting results as a consequences of small differences in instrumentation. Traditional methods of microwave spectroscopy that make use of time-domain spectrometers or network analyzer systems provide only indirect measurement of the microwave absorption coefficient because they measure the real and imaginary parts of the dielectric constant, ε' and ε'', separately. The absorption coefficient must then be calculated from ε' and ε'' taking into account the geometry (e.g., of the waveguide and mode) among other factors. It has been shown that direct measurement of the microwave absorption coefficient α is possible using phase fluctuation optical heterodyne spectroscopy. Taking advantage of this hybrid optical-microwave technique the authors report on a broadband spectrometer with demonstrated accurate operation from 3 to 20 GHz

  17. Coupled Lines Filters for Broadband Impedance Matching of Microwave Amplifiers

    Directory of Open Access Journals (Sweden)

    Mohammed Lahsaini

    2014-08-01

    Full Text Available In this paper we present a broadband matching technique for the design of low noise amplifiers. This technique is based on the use of coupled lines filters and quarter wave transformers for the adaptation and stabilization of these amplifiers, presenting the theory and the design process of these circuits. The type of transistors used for modeling this amplifier is the HEMT of Alpha Industries®. The results we found show that this amplifier is unconditionally stable with a satisfactory gain of about 20 dB and good impedance matching across the band of interest [10-12] GHz. The amplifier modeled in this work can be integrated in satellite receiving systems and radar systems.

  18. Improving TCP Performance of DOCSIS Based Broadband Networks

    Directory of Open Access Journals (Sweden)

    Wissam Al-Khatib

    2006-01-01

    Full Text Available Data-Over-Cable Service Interface Specifications (DOCSIS is developed for data transmissions over cable networks; it is intended to support IP flows with significantly higher data rate links for high quality data, audio, video and interactive services. It is important to provide traffic scheduling mechanisms to support Quality of Service (QoS for such applications. This study analyses the TCP performance over DOCSIS protocol in HFC broadband networks and also proposes an algorithm to improve the TCP performance. Simulations were in done in ns-2 with simple modification in MAC layer. The result proves that the proposed algorithm have less access delay, good throughput and good channel utilization when compared existing DOCSIS protocol.

  19. Broadband reflectionless metasheets: Frequency-selective transmission and perfect absorption

    CERN Document Server

    Asadchy, V S; Ra'di, Y; Khakhomov, S A; Semchenko, I V; Tretyakov, S A

    2015-01-01

    Energy of propagating electromagnetic waves can be fully absorbed in a thin lossy layer, but only in a narrow frequency band, as follows from the causality principle. On the other hand, it appears that there are no fundamental limitations on broadband matching of thin absorbing layers. However, known thin absorbers produce significant reflections outside of the resonant absorption band. In this paper we explore possibilities to realize a thin absorbing layer which produces no reflected waves in a very wide frequency range, while the transmission coefficient has a narrow peak of full absorption. Here we show, both theoretically and experimentally, that a wide-band-matched thin resonant absorber, invisible in reflection, can be realized if one and the same resonant mode of the absorbing array unit cells is utilized to create both electric and magnetic responses. We test this concept using chiral particles in each unit cells, arranged in a periodic planar racemic array, utilizing chirality coupling in each unit ...

  20. Synchronously pumped femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūte, Karolina; Melnikas, Simas; Kičas, Simonas; Trišauskas, Lukas; Vengelis, Julius; Grigonis, Rimantas; Vengris, Mikas; Sirutkaitis, Valdas

    2015-05-01

    We present results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) with broadband complementary chirped mirror pairs (CMP). The SPOPO based on β-BBO nonlinear crystal is pumped by second harmonic of femtosecond Yb:KGW laser and provides signal pulses tunable over spectral range from 625 to 980 nm. More than 500 mW are generated in the signal beam, giving up to 27 % pump power to signal power conversion efficiency. The plane SPOPO cavity mirror pairs were specially designed to provide 99 % reflection in broad spectral range corresponding to signal wavelength tuning (630-1030 nm) and to suppress group delay dispersion (GDD) oscillations down to +/-10 fs2. Dispersion properties of designed mirrors were tested with white light interferometer (WLI) and attributed to the SPOPO tuning behaviour.

  1. Broadband sample holder for microwave spectroscopy of superconducting qubits

    International Nuclear Information System (INIS)

    We present a practical design and implementation of a broadband sample holder suitable for microwave experiments with superconducting integrated circuits at millikelvin temperatures. Proposed design can be easily integrated in standard dilution cryostats, has flat pass band response in a frequency range from 0 to 32 GHz, allowing the RF testing of the samples with substrate size up to 4 × 4 mm2. The parasitic higher modes interference in the holder structure is analyzed and prevented via design considerations. The developed setup can be used for characterization of superconducting parametric amplifiers, bolometers, and qubits. We tested the designed sample holder by characterizing of a superconducting flux qubit at 20 mK temperature

  2. A Broadband Terahertz Waveguide T-Junction Variable Power Splitter.

    Science.gov (United States)

    Reichel, Kimberly S; Mendis, Rajind; Mittleman, Daniel M

    2016-01-01

    In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting. PMID:27352772

  3. Broadband highly-efficient dielectric metadevices for polarization control

    CERN Document Server

    Kruk, Sergey; Kravchenko, Ivan; Miroshnichenko, Andrey; Neshev, Dragomir N; Kivshar, Yuri S

    2016-01-01

    Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms to achieve destructive interference in reflection over a large spectral bandwidth. By employing this novel concept, we demonstrate reflectionless (~90% transmission) half-wave plates, quarter-wave plates, and vector beam q-plates that can operate across multiple telecom bands with ~99% polarization conversion efficiency.

  4. Observation of Broadband Time-Dependent Rabi Shifting in Microplasmas

    International Nuclear Information System (INIS)

    Coherent broadband radiation in the form of Rabi sidebands is observed when a ps probe laser propagates through a weakly ionized, electronically excited microplasma generated in the focus of an intense pump beam. The sidebands arise from the interaction of the probe beam with pairs of excited states of a constituent neutral atom via the probe-induced Rabi oscillation. Sideband shifting of >90 meV from the probe carrier frequency results in an effective bandwidth of 200 meV. The sidebands are controlled by the intensity and temporal profile of the probe pulse; with amplitude and shift in agreement with the predictions of a time-dependent generalized Rabi cycling model.

  5. Three-dimensional broadband omnidirectional acoustic ground cloak.

    Science.gov (United States)

    Zigoneanu, Lucian; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-04-01

    The control of sound propagation and reflection has always been the goal of engineers involved in the design of acoustic systems. A recent design approach based on coordinate transformations, which is applicable to many physical systems, together with the development of a new class of engineered materials called metamaterials, has opened the road to the unconstrained control of sound. However, the ideal material parameters prescribed by this methodology are complex and challenging to obtain experimentally, even using metamaterial design approaches. Not surprisingly, experimental demonstration of devices obtained using transformation acoustics is difficult, and has been implemented only in two-dimensional configurations. Here, we demonstrate the design and experimental characterization of an almost perfect three-dimensional, broadband, and, most importantly, omnidirectional acoustic device that renders a region of space three wavelengths in diameter invisible to sound. PMID:24608143

  6. Cavity-Enhanced Room-Temperature Broadband Raman Memory

    Science.gov (United States)

    Saunders, D. J.; Munns, J. H. D.; Champion, T. F. M.; Qiu, C.; Kaczmarek, K. T.; Poem, E.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.

    2016-03-01

    Broadband quantum memories hold great promise as multiplexing elements in future photonic quantum information protocols. Alkali-vapor Raman memories combine high-bandwidth storage, on-demand readout, and operation at room temperature without collisional fluorescence noise. However, previous implementations have required large control pulse energies and have suffered from four-wave-mixing noise. Here, we present a Raman memory where the storage interaction is enhanced by a low-finesse birefringent cavity tuned into simultaneous resonance with the signal and control fields, dramatically reducing the energy required to drive the memory. By engineering antiresonance for the anti-Stokes field, we also suppress the four-wave-mixing noise and report the lowest unconditional noise floor yet achieved in a Raman-type warm vapor memory, (15 ±2 )×10-3 photons per pulse, with a total efficiency of (9.5 ±0.5 )%.

  7. Metamaterial-based perfect absorber: polarization insensitivity and broadband

    International Nuclear Information System (INIS)

    We report the design and simulation of a microwave metamaterials-based perfect absorber using a simple and highly symmetric structure. The basic structure consists of three functional layers: the middle is a dielectric, the back is a metallic plane and the front is a ring of metal. The influence of structural parameters on the absorbance and absorption frequency were investigated. The results show an exceptional absorption performance of near unity around 16 GHz. In addition, the absorption is insensitive to the polarization of the incident beam due to the highly symmetric structure. Finally, four and nine rings with different sizes are arranged appropriately in a unit cell in order to construct a broadband absorber. A polarization-insensitive absorbance of above 90% is achieved over a bandwidth of 15%. (papers)

  8. Chirped photonic crystals: a natural strategy for broadband reflectance

    CERN Document Server

    Cook, Caleb Q

    2016-01-01

    One-dimensional photonic crystals with slowly varying, i.e. "chirped", lattice period are responsible for broadband light reflectance in many diverse biological contexts, ranging from the shiny coatings of various beetles to the eyes of certain butterflies. We present a quantum scattering analogy for light reflection from these adiabatically chirped photonic crystals (ACPCs) and apply a WKB-type approximation to obtain a closed-form expression for the reflectance. From this expression we infer several design principles, including a differential equation for the chirp pattern required to elicit a given reflectance spectrum and the minimal number of bilayers required to exceed a desired reflectance threshold. Comparison of the number of bilayers found in ACPCs throughout nature and our predicted minimal required number also gives a quantitative measure of the optimality of chirped biological reflectors. Together these results elucidate the design principles of chirped reflectors in nature and their possible app...

  9. Broadband Meter-Wavelength Observations of Ionospheric Scintillation

    CERN Document Server

    Fallows, R A; McKay, D; Vierinen, J; Virtanen, I I; Postila, M; Ulich, Th; Enell, C-F; Kero, A; Iinatti, T; Lehtinen, M; Orispää, M; Raita, T; Roininen, L; Turunen, E; Brentjens, M; Ebbendorf, N; Gerbers, M; Grit, T; Gruppen, P; Meulman, H; Norden, M; de Reijer, J-P; Schoenmakers, A; Stuurwold, K

    2015-01-01

    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally these observations are relatively narrow band. With Low Frequency Array (LOFAR) technology at the Kilpisj\\"arvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a 3 octave bandwidth. ``Parabolic arcs'', which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broad-band observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250\\,MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disapp...

  10. Motional narrowing of broadband absorption of solvatochromic indicator Betaine 30

    Energy Technology Data Exchange (ETDEWEB)

    Renge, Indrek [Institute of Physics, University of Tartu, Riia Street 142, EE51014 Tartu (Estonia)], E-mail: indrek.renge@ut.ee

    2009-05-15

    Temperature dependence of the absorption spectra of Betaine 30 (2,6-diphenyl-4-(2,4,6-triphenylpyridinio)-phenolate, widely known as Reichardt's dye) is compared with that of the broadband spectra of other dyes. The double value of the half-width (2 hwhm) of Betaine 30 absorption band between 10 and 293 K in a polymer decreases by 130{+-}20 cm{sup -1}, from 4220 to 4090 cm{sup -1}. This unprecedented narrowing with increasing temperature is ascribed to hydrogen bond symmetrization due to thermally activated proton tunneling in a pigment-solvent complex. The averaging of charge distribution along the proton coordinate causes motional narrowing of inhomogeneous width.

  11. Evaluation of the broadband longitudinal impedance of the CERN PS

    CERN Document Server

    Damerau, H; Hancock, S; Migliorati, M; Palumbo, L; Persichelli, S; CERN. Geneva. ATS Department

    2012-01-01

    The CERN Proton Synchrotron (PS) produces beams well beyond its original parameters and especially the high-brightness beams delivered to the Large Hadron Collider are close to present stability limitations. Within the framework of the LHC Injectors Upgrade project, a signicant increase in beam intensity is planned. With this background, collective effects triggered by the self-induced electromagnetic elds, which are generated by the interaction of the beam with the surrounding environment, may play an important role in beam stability and machine performance. In this paper we study the short range wakeelds and the corresponding longitudinal broadband coupling impedance of the PS by measuring the incoherent quadrupole synchrotron frequency as a function of beam intensity and comparing the results with the evaluation of the contribution of several machine installations to the total impedance budget.

  12. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    Science.gov (United States)

    Washenfelder, R. A.; Flores, J. M.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2013-04-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  13. Ultra-broadband supercontinuum generation in fluoride glass by filamentation

    Science.gov (United States)

    Liao, Meisong; Ohishi, Yasutake

    2014-10-01

    The mid-IR supercontinuum (SC) light source is in demand for many chemical, biological, medical, and astronomical applications. It is of great significance to develop a mid-IR SC light source whose spectrum is wide and flat. We obtained ultra-broadband mid-IR SC by using a piece of fluoride glass through filamentation. Though the SC generation by filamentation needs a powerful laser chain to be the pump source, it has some advantages in comparison with that based on fiber. First, the optical path length in the glass can be very short due to the adopted high pump power. The negative influence of accumulated loss can be reduced greatly, so the transparent range of glass is much larger than fiber. Secondly, it is convenient in light-coupling, and the coupling efficiency can be high. In comparison with it, the coupling of the small core (usually the core is small to ensure a high nonlinearity) mid-IR glass fiber is troublesome. Thirdly, the glass piece is cost-effective, and can be fabricated easily. We obtained a SC spectrum covering 0.2-8.0 μm by using a 32mm-thick fluoride glass sample. The 3 dB bandwidth covers 1.15-4.76 μm. The 20 dB bandwidth spans from 0.39 to 7.4 μm. The glass thickness, optical path, and pump conditions are optimized to enable the SC to be as wide as possible. This work shows that the SC generation through filamentation in bulk glass can be an effective way to obtain an ultra-broadband mid-IR light source, which will find various applications in mid-IR regions.

  14. New Developments of Broadband Cavity Enhanced Spectroscopic Techniques

    Science.gov (United States)

    Walsh, A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2013-06-01

    In recent years, cavity enhanced spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), cavity enhanced absorption spectroscopy (CEAS), and broadband cavity enhanced absorption spectroscopy (BBCEAS), have been widely employed as ultra-sensitive methods for the measurement of weak absorptions and in the real-time detection of trace species. In this contribution, we introduce two new cavity enhanced spectroscopic concepts: a) Optomechanical shutter modulated BBCEAS, a variant of BBCEAS capable of measuring optical absorption in pulsed systems with typically low duty cycles. In conventional BBCEAS applications, the latter substantially reduces the signal-to-noise ratio (S/N), consequently also reducing the detection sensitivity. To overcome this, we incorporate a fast optomechanical shutter as a time gate, modulating the detection scheme of BBCEAS and increasing the effective duty cycle reaches a value close to unity. This extends the applications of BBCEAS into pulsed samples and also in time-resolved studies. b) Cavity enhanced self-absorption spectroscopy (CESAS), a new spectroscopic concept capable of studying light emitting matter (plasma, flames, combustion samples) simultaneously in absorption and emission. In CESAS, a sample (plasma, flame or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. A high detection sensitivity of weak absorption is reached without the need of an external light source, such as a laser or broadband lamp. The performance is illustrated by the first CESAS result on a supersonically expanding hydrocarbon plasma. We expect CESAS to become a generally applicable analytical tool for real time and in situ diagnostics. A. Walsh, D. Zhao, W. Ubachs, H. Linnartz, J. Phys. Chem. A, {dx.doi.org/10.1021/jp310392n}, in press, 2013. A. Walsh, D. Zhao, H. Linnartz Rev. Sci. Instrum. {84}(2), 021608 2013. A. Walsh, D. Zhao

  15. Parallel Processing of Broad-Band PPM Signals

    Science.gov (United States)

    Gray, Andrew; Kang, Edward; Lay, Norman; Vilnrotter, Victor; Srinivasan, Meera; Lee, Clement

    2010-01-01

    A parallel-processing algorithm and a hardware architecture to implement the algorithm have been devised for timeslot synchronization in the reception of pulse-position-modulated (PPM) optical or radio signals. As in the cases of some prior algorithms and architectures for parallel, discrete-time, digital processing of signals other than PPM, an incoming broadband signal is divided into multiple parallel narrower-band signals by means of sub-sampling and filtering. The number of parallel streams is chosen so that the frequency content of the narrower-band signals is low enough to enable processing by relatively-low speed complementary metal oxide semiconductor (CMOS) electronic circuitry. The algorithm and architecture are intended to satisfy requirements for time-varying time-slot synchronization and post-detection filtering, with correction of timing errors independent of estimation of timing errors. They are also intended to afford flexibility for dynamic reconfiguration and upgrading. The architecture is implemented in a reconfigurable CMOS processor in the form of a field-programmable gate array. The algorithm and its hardware implementation incorporate three separate time-varying filter banks for three distinct functions: correction of sub-sample timing errors, post-detection filtering, and post-detection estimation of timing errors. The design of the filter bank for correction of timing errors, the method of estimating timing errors, and the design of a feedback-loop filter are governed by a host of parameters, the most critical one, with regard to processing very broadband signals with CMOS hardware, being the number of parallel streams (equivalently, the rate-reduction parameter).

  16. BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550-5418 BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lin Lin; Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I Tuzla, Istanbul 34956 (Turkey); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander; Watts, Anna L. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Gruber, David; Von Kienlin, Andreas [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85748 Garching bei Mnchen (Germany); Younes, George [USRA, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, Neil, E-mail: linlin@sabanciuniv.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  17. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    Science.gov (United States)

    Lin, Lin; Goegues, Ersin; Baring, Matthew G.; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L.; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  18. Tunable Dielectric Materials and Devices for Broadband Wireless Communications

    Science.gov (United States)

    Mueller, Carl H.; Miranda, Felix A.; Dayton, James A. (Technical Monitor)

    1998-01-01

    Wireless and satellite communications are a rapidly growing industries which are slated for explosive growth into emerging countries as well as countries with advanced economies. The dominant trend in wireless communication systems is towards broadband applications such as multimedia file transfer, video transmission and Internet access. These applications require much higher data transmission rates than those currently used for voice transmission applications. To achieve these higher data rates, substantially larger bandwidths and higher carrier frequencies are required. A key roadblock to implementing these systems at K-band (18-26.5 GHz) and Ka-band (26.5-40 GHz) is the need to develop hardware which meets the requirements for high data rate transmission in a cost effective manner. In this chapter, we report on the status of tunable dielectric thin films for devices, such as resonators, filters, phased array antennas, and tunable oscillators, which utilize nonlinear tuning in the control elements. Paraelectric materials such as Barium Strontium Titanate ((Ba, Sr)TiO3) have dielectric constants which can be tuned by varying the magnitude of the electric field across the material. Therefore, these materials can be used to control the frequency and/or phase response of various devices such as electronically steerable phased array antennas, oscillators, and filters. Currently, tunable dielectric devices are being developed for applications which require high tunability, low loss, and good RF power-handling capabilities at microwave and millimeter-wave frequencies. These properties are strongly impacted by film microstructure and device design, and considerable developmental work is still required. However, in the last several years enormous progress has occurred in this field, validating the potential of tunable dielectric technology for broadband wireless communication applications. In this chapter we summarize how film processing techniques, microwave test

  19. Three-dimensional broadband intensity probe for measuring acoustical parameters

    Science.gov (United States)

    Miah, Khalid Hossain

    Measuring different acoustical properties have been the key in reducing noise and improving the sound quality from various sources. In this report, a broadband (200 Hz -- 6.5 kHz) three-dimensional seven-microphone intensity probe system is developed to measure the sound intensity, and total energy density in different acoustical environments. Limitations of most commercial intensity probes in measuring the three-dimensional intensity for a broadband sound field was the main motivation in developing this probe. The finite-difference error and the phase mismatch error which are the two main errors associated with the intensity measurements are addressed in this report. As for the physical design, seven microphones were arranged in a two-concentric arrays with one microphone located at the center of the probe. The outer array is for low-frequencies (200 Hz -- 1.0 kHz), and the inner one is for high-frequencies (1.0 kHz -- 6.5 kHz). The screw adjustable center microphone is used for the microphone calibration, and as the reference microphone of the probe. The simultaneous calibrations of all the microphones in the probe were done in the anechoic room. Theories for the intensity and the energy densities calculations for the probe were derived from the existing four-microphone probe configuration. Reflection and diffraction effects on the intensity measurements due to the presence of the microphones, and the supporting structures were also investigated in this report. Directivity patterns of the calculated intensity showed the omnidirectional nature of the probe. The intensity, and total energy density were calculated and compared with the ideal values in the anechoic room environment. Characterization of sound fields in a reverberant enclosed space, and sound source identification are some applications that were investigated using this probe. Results of different measurements showed effectiveness of the probe as a tool to measure key acoustical properties in many

  20. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    Directory of Open Access Journals (Sweden)

    R. A. Washenfelder

    2013-01-01

    Full Text Available Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross-sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED and a grating spectrometer with charge-coupled device (CCD detector. We determined aerosol extinction cross-sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate, slightly absorbing (Suwannee River fulvic acid, and strongly absorbing (nigrosin dye. We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross-sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (±0.03 + 0.19 (±0.08 i at 360 nm and 1.53 (±0.03 + 0.21 (±0.05 i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (±0.02 + 0.07 (±0.06 i at 360 nm and 1.66 (±0.02 + 0.06 (±0.04 i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross-section, and complex refractive index as a function of wavelength.

  1. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    Directory of Open Access Journals (Sweden)

    R. A. Washenfelder

    2013-04-01

    Full Text Available Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED and a grating spectrometer with charge-coupled device (CCD detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate, slightly absorbing (Suwannee River fulvic acid, and strongly absorbing (nigrosin dye. We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03 + 0.19 (± 0.08i at 360 nm and 1.63 (± 0.03 + 0.21 (± 0.05i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02 + 0.07 (± 0.06i at 360 nm and 1.66 (± 0.02 + 0.06 (± 0.04i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  2. Broadband nanophotonic wireless links and networks using on-chip integrated plasmonic antennas.

    Science.gov (United States)

    Yang, Yuanqing; Li, Qiang; Qiu, Min

    2016-01-01

    Owing to their high capacity and flexibility, broadband wireless communications have been widely employed in radio and microwave regimes, playing indispensable roles in our daily life. Their optical analogs, however, have not been demonstrated at the nanoscale. In this paper, by exploiting plasmonic nanoantennas, we demonstrate the complete design of broadband wireless links and networks in the realm of nanophotonics. With a 100-fold enhancement in power transfer superior to previous designs as well as an ultrawide bandwidth that covers the entire telecommunication wavelength range, such broadband nanolinks and networks are expected to pave the way for future optical integrated nanocircuits. PMID:26783033

  3. Theory and design of broadband matching networks applied electricity and electronics

    CERN Document Server

    Chen, Wai-Kai

    1976-01-01

    Theory and Design of Broadband Matching Networks centers on the network theory and its applications to the design of broadband matching networks and amplifiers. Organized into five chapters, this book begins with a description of the foundation of network theory. Chapter 2 gives a fairly complete exposition of the scattering matrix associated with an n-port network. Chapter 3 considers the approximation problem along with a discussion of the approximating functions. Chapter 4 explains the Youla's theory of broadband matching by illustrating every phase of the theory with fully worked out examp

  4. Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

    Directory of Open Access Journals (Sweden)

    P. Pignalosa

    2011-09-01

    Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

  5. High efficiency third-harmonic generation of broadband Nd: glass laser

    International Nuclear Information System (INIS)

    The paper proposes and numerically demonstrates a simple and efficient broadband frequency-tripling scheme for Nd: glass laser system based on mixing narrowband and broadband laser pulses in the sum-frequency generation (SFG) process. The group-velocity mismatching effect in the of SFG process is substantially alleviated with the assist of a narrowband laser, which is the dominant obstacle to efficient broadband third-harmonic generation. Moreover, by adding a second tripler in the SFG process, the proposed scheme will support efficient frequency tripling over a bandwidth of 5 nm (theoretical efficiency more than 80%). (authors)

  6. Visible broadband magnetic response from Ag chiral Z-shaped nanohole array

    CERN Document Server

    Han, Chunrui

    2015-01-01

    We show that broadband magnetic response in visible range can be achieved through an Ag chiral Z-shaped nanohole array. The broadband effect is realized by incorporating multi-scaled inverted SRRs and metal/dielectric nanostrip antenna in one unit cell of only 260 nm square lattice, resulting in multiple excitations of magnetic resonances at different wavelengths. The collective modes show structure dependence and respond separately to LCP and RCP incident light. The Ag Z- and reverse-Z-shaped nanohole arrays have been experimentally realized by shadowing vapor deposition method which exhibit broadband transmission difference, in good agreement with numerical simulations.

  7. Broadband nanophotonic wireless links and networks using on-chip integrated plasmonic antennas

    Science.gov (United States)

    Yang, Yuanqing; Li, Qiang; Qiu, Min

    2016-01-01

    Owing to their high capacity and flexibility, broadband wireless communications have been widely employed in radio and microwave regimes, playing indispensable roles in our daily life. Their optical analogs, however, have not been demonstrated at the nanoscale. In this paper, by exploiting plasmonic nanoantennas, we demonstrate the complete design of broadband wireless links and networks in the realm of nanophotonics. With a 100-fold enhancement in power transfer superior to previous designs as well as an ultrawide bandwidth that covers the entire telecommunication wavelength range, such broadband nanolinks and networks are expected to pave the way for future optical integrated nanocircuits.

  8. Comparative Noise Performance of Portable Broadband Sensor Emplacements

    Science.gov (United States)

    Sweet, Justin; Arias-Dotson, Eliana; Beaudoin, Bruce; Anderson, Kent

    2015-04-01

    IRIS PASSCAL has supported portable broadband seismic experiments for close to 30 years. During that time we have seen a variety of sensor vaults deployed. The vaults deployed fall into two broad categories, a PASSCAL style vault and a Flexible Array style vault. The PASSCAL vault is constructed of materials available in-county and it is the Principle Investigator (PI) who establishes the actual field deployed design. These vaults generally are a large barrel placed in a ~1 m deep hole. A small pier, decoupled from the barrel, is fashioned in the bottom of the vault (either cement, paving stone or tile) for the sensor placement. The sensor is insulated and protected. Finally the vault is sealed and buried under ~30 cm of soil. The Flexible Array vault is provided to PIs by the EarthScope program, offering a uniform portable vault for these deployments. The vault consists of a 30 cm diameter by 0.75 cm tall piece of plastic sewage pipe buried with ~10 cm of pipe above grade. A rubber membrane covers the bottom and cement was poured into the bottom, coupling the pier to the pipe. The vault is sealed and buried under ~30 cm of soil. Cost, logistics, and the availability of materials in-country are usually the deciding factors for PIs when choosing a vault design and frequently trades are made given available resources. Recently a third type of portable broadband installation, direct burial, is being tested. In this case a sensor designed for shallow, direct burial is installed in a ~20 cm diameter by ~1 m deep posthole. Direct burial installation costs are limited to the time and effort required to dig the posthole and emplace the sensor. Our initial analyses suggest that direct burial sensors perform as well and at times better than sensor in vaults on both horizontal and vertical channels across a range of periods (<1 s to 100 s). Moving towards an instrument pool composed entirely of direct burial sensors (some with integrated digitizers) could yield higher

  9. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    International Nuclear Information System (INIS)

    Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer–Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements

  10. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    Science.gov (United States)

    Sanchez, B.; Vandersteen, G.; Bragos, R.; Schoukens, J.

    2011-11-01

    Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer-Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements when

  11. Determination of the broadband optical properties of biomass burning aerosol

    Science.gov (United States)

    Bluvshtein, Nir; Flores, J. Michel; Segev, Lior; Lin, Peng; Laskin, Alexander; Rudich, Yinon

    2016-04-01

    The direct and semi-direct effects of atmospheric aerosol on the Earth's energy balance are still the two of the largest uncertainties in our understanding of anthropogenic radiative forcing. In this study we developed a new approach for determining high sensitivity broadband UV-Vis spectrum (300-650 nm) of extinction, scattering and absorption coefficients, single scattering albedo and the complex refractive index for continuous, spectral and time dependent, monitoring of polydisperse aerosols population. This new approach was applied in a study of biomass burning aerosol. Extinction, scattering and absorption coefficients (αext, αsca, αabs, respectively) were continually monitored using photoacoustic spectrometer coupled to a cavity ring down spectrometer (PA-CRD-AS) at 404 nm, a dual-channel Broadband cavity-enhanced spectrometer (BBCES) at 315-345 nm and 390-420 nm and a three channel integrating nephelometer (IN) centered at 457, 525 and 637 nm. During the biomass burning event, the measured aerosol number concentration increased by more than an order of magnitude relative to other week nights and the mode of the aerosols size distribution increased from 40-50 nm to 110nm diameter. αext and αsca increased by a factor of about 5.5 and 4.5, respectively. The αabs increased by a factor over 20, indicating a significant change in the aerosol overall chemical composition. The imaginary part of the complex RI at 404nm increased from its background level at about 0.02 to a peak of about 0.08 and the SSA decreased from 0.9 to about 0.6. Significant change of the absorption spectral dependence indicates formation of visible-light absorbing compounds. The mass absorption cross section of the water soluble organic aerosol (MACWSOA) reached up to about 12% of the corresponding value for black carbon (BC) at 450 nm and up to 30% at 300 nm. These results demonstrate the importance of biomass burning in understanding global and regional radiative forcing.

  12. Ultimate VHF Broadband Interferometer Zen KAWASAKI and Manabu AKITA

    Science.gov (United States)

    Kawasaki, Z.; Akita, M.

    2013-12-01

    propagation, like electromagnetic wave propagation in non-dispersive medium. This procedure presented exciting results of lightning channel imaging, and the bi-directional leader propagation can be visualized in terms of azimuth and elevation as a function of time. Moreover all of the VHF radiation process for an entire lightning flash from initiation to termination can be imaged, and it is concluded that the system might be an ultimate broad band digital interferometer. The authors would like to show their appreciation to Paul Krehbiel, NMIMT, who gave a chance and suggestion of a continuous recording scheme for BDITF. M. Stock et al. : Continuous Broadband Digital Interferometry of Lightning using a Generalized Cross Correlation Algorithm M. Akita et al. : Data Processing Procedure 1 using Distribution of Slopes of Phase Differences for Broadband VHF Interferometer

  13. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces

    CERN Document Server

    Pala, Ragip A; Aydin, Koray; Atwater, Harry A

    2015-01-01

    Light trapping in planar ultrathin-film solar cells is limited due to a small number of optical modes available in the thin-film slab. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local density of states in a subwavelength volume and maintaining efficient coupling of light. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelength-scale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theoretically and experimentally in prototypes consisting of lithographically patterned, two-dimensional periodic arrays of silicon nanoresonators on silica substrates. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across the visible and near-IR spectra. Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements ...

  14. Neural networks using broadband spectral discriminators reduces illumination required for broccoli identification in weedy fields

    Science.gov (United States)

    Hahn, Federico

    1996-03-01

    Statistical discriminative analysis and neural networks were used to prove that crop/weed/soil discrimination by optical reflectance was feasible. The wavelengths selected as inputs on those neural networks were ten nanometers width, reducing the total collected radiation for the sensor. Spectral data collected from several farms having different weed populations were introduced to discriminant analysis. The best discriminant wavelengths were used to build a wavelength histogram which selected the three best spectral broadbands for broccoli/weed/soil discrimination. The broadbands were analyzed using a new single broadband discriminator index named the discriminative integration index, DII, and the DII values obtained were used to train a neural network. This paper introduces the index concept, its results and its use for minimizing artificial lightning requirements with broadband spectral measurements for broccoli/weed/soil discrimination.

  15. Broadband Direct UVA irradiance measurement for clear skies evaluated using a smartphone

    International Nuclear Information System (INIS)

    UVA wavelengths (320-400 nm) have been implicated in recent studies to contribute to melanoma induction and skin photo-aging in humans and damage to plants. The use of smartphones in UVA observations is a way to supplement measurements made by traditional radiometric and spectro-radiometric technology. Although the smartphone image sensor is not capable of determining broadband UVA irradiances, these can be reconstructed from narrowband irradiances, which the smartphone, with narrowband and neutral density filters, can quantify with discrepancies not exceeding 5 %. Three models that reconstruct direct broadband clear sky UVA were developed from narrowband irradiances derived from smartphone image sensor pixel data with coefficients of determination of between 0.97 and 0.99. Reasonable accuracy and precision in determining the direct broadband UVA was maintained for observations made with solar zenith angles as high as 70 deg. . The developed method has the potential to increase the uptake of the measurement of broadband UVA irradiances. (authors)

  16. Making structured metals transparency for broadband and wide-incidence-angle electromagnetic waves

    Science.gov (United States)

    Fan, Renhao; Peng, Ruwen; Huang, Xianrong; Wang, Mu

    2014-03-01

    Very recently, we have demonstrated that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic (EM) waves under oblique incidence. However, the oblique-incidence geometry, is inconvenient for the technological applications. To overcome this drawback, here we instead use oblique metal gratings with optimal tilt angles to achieve normal-incidence broadband transparence for EM waves. Further we use two-dimensional periodic metallic cuboids to achieve broadband and broad-angle high transmission and antireflection. By introducing such metallic cuboids arrays into silicon solar cells, we find that high performance of light trapping in the cells can be obtained with a significant enhancement of the ultimate quantum efficiency. The structured metals, which achieve broadband and broad-angle high transmission for EM waves, may have many other potential applications, such as transparent conducting panels, white-beam polarizers, and stealth objects.

  17. Acousto-Optics Tunable Filter Based on a Hollow Optical Fiber for Broadband Polarization Switch Application

    Institute of Scientific and Technical Information of China (English)

    Jaewon; Lee; Jaewang; Yu; Sangsoo; Choi; Kyunghwan; Oh; Dong; Il; Yum; Byoung; Yoon; Kim

    2003-01-01

    A novel acousto-optic tunable filter (AOTF) using a hollow optical fiber (HOF) is proposed. Its broadband rejection over 100nm was observed and high polarization dependence as a polarization switch is discussed.

  18. 3D broadband isotropic NRI metamaterial based on metallic cross-pairs

    International Nuclear Information System (INIS)

    In this paper, a new type of 3D metamaterial composed of double periodic array of metallic cross-pairs printed on the six sides of a cubic dielectric substrate was proposed to obtain the characteristics of broadband NRI and isotropy for the applications of super lenses. The behaviors of NRI, isotropy and polarization were analyzed using the CST Microwave Studio. The results show that the proposed metamaterial exhibits not only a broadband NRI whose relative bandwidth can be up to 56.7%, but also polarization-independence and isotropy. Thus, the proposed metamaterial is a good candidate material for 3D broadband isotropic NRI metamaterial. - Highlights: → 3D metamaterial is composed of double periodic array of metallic cross-pairs printed on the six sides of a cubic dielectric substrate. → Broadband negative refraction index (NRI) with relative bandwidth of 56.7%. → Polarization-independence and isotropy.

  19. Broadband Wireline Provider Service: Other Copper Wireline; BBRI_otherCopper12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Other Copper Wireline" technology. In Rhode Island, this...

  20. High Temperature and High QE Broadband Longwave Infrared SLS FPA for LANDSAT Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a high-performance broadband infrared focal plane array (FPA) for the Thermal Infrared Sensor (TIRS) on NASA's LANDSAT satellite. The FPA will feature a...

  1. Meta-atom cluster acoustic metamaterial with broadband negative effective mass density

    International Nuclear Information System (INIS)

    We design a resonant meta-atom cluster, via which a two-dimensional (2D) acoustic metamaterial (AM) with broadband negative effective mass density from 1560 Hz to 5580 Hz is fabricated. Experimental results confirm that there is only weak interaction among the meta-atoms in the cluster. And then the meta-atoms in the cluster independently resonate, resulting in the cluster becoming equivalent to a broadband resonance unit. Extracted effective refractive indices from reflection and transmission measurements of the 2D AM appear to be negative from 1500 Hz to 5480 Hz. The broadband negative refraction has also been demonstrated by our further experiments. We expect that this meta-atom cluster AM will significantly contribute to the design of broadband negative effective mass density AM

  2. Propagation characteristics of nanometer-level broadband chirped pulse in high power laser system

    International Nuclear Information System (INIS)

    High frequency spatial modulation induced by Fresnel diffraction of broadband nanosecond chirped laser pulse were studied. It shows that the hundreds-nm broadband pulse has some effects of Fresnel diffraction, while the tens-nm one has hardly any. Moreover, three B-integral expressions and the fast gain frequency of tens-nm broadband nanosecond chirped laser pulse were studied, and compared with the nonlinear experiments of narrowband pulse and chirped pulse stacking on prototype facility. The results reveal that, the maximal B-integral or the weighted average B-integral can better reflect the nonlinear self-focusing phenomenon, and there are no distinct differences between the narrowband and the tens-nm broadband nanosecond laser pulses with respect to the fast gain frequency. (authors)

  3. 76 FR 62309 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

    Science.gov (United States)

    2011-10-07

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Chapter I Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this...

  4. Characteristics of a Broadband Dye Laser Using Pyrromethene and Rhodamine Dyes

    Science.gov (United States)

    Tedder, Sarah A.; Danehy, Paul M.; Wheeler, Jeffrey L.

    2011-01-01

    A broadband dye laser pumped by a frequency-doubled Nd:YAG laser with a full-width half-maximum (FWHM) from 592 to 610 nm was created for the use in a dual-pump broadband CARS system called WIDECARS. The desired broadband dye laser was generated with a mixture of Pyrromethene dyes as an oscillator gain medium and a spectral selective optic in the oscillator cavity. A mixture of Rhodamine dyes were used in the amplifier dye cell. To create this laser a study was performed to characterize the spectral behavior of broadband dye lasers created with Rhodamine dyes 590, 610, and 640, Pyrromethene dyes 597 and 650 as well as mixture of these dyes.

  5. Multi-Criteria Comparison Between Legacy and Next Generation Point of Presence Broadband Network Architectures

    Directory of Open Access Journals (Sweden)

    Moufida Feknous

    Full Text Available Development of new applications and the introduction of innovative technologies can lead to revise network architectures in order to build sustainable broadband infrastructures. The present paper describes the main drivers and enabling technologies leadin ...

  6. Modelling of Remote Area Broadband Technology Over Low Voltage Power Line Channel

    Directory of Open Access Journals (Sweden)

    Abdallah Mahmoud Mousa Altrad

    2012-10-01

    Full Text Available Several broadband development initiatives have been proposed in Malaysia in order to Bridging DigitalDivide (BDD through the provisions of the Information and Communication Technology (ICT servicesto facilitate wide access to the internet through corporates government and private sector for high levelof scio-economy. Nevertheless, there is delay in provide broadband services due to the high cost ofdeployment in the remote area. Therefore, this paper investigates on Broadband over Power Lines (BPLtechnology and Malaysia’s broadband initiatives. BPL transmission technology model of using electricalpower lines for data, video and voice transmission is proposed. Furthermore, indoor part of theproposed model is carried out on Matlab/Simulink to explore the validity of power line channel transferfunction.

  7. Improvement of broadband seismic station installations at the Observatoire de Grenoble (OSUG) seismic network

    OpenAIRE

    Langlais, M; B. Vial; Coutant, O.

    2013-01-01

    We describe in this paper different improvements that were brought to the installation of seismic broadband stations deployed by the Observatoire de Grenoble (OSUG) in the northern French Alps. This work was realized in the frame of a French-Italian ALCOTRA project (RISE), aimed at modernizing the broadband seismic networks across our common border. We had the opportunity with this project to improve some of our seismic recording sites, both in term of sensor installation qu...

  8. Metasurface-based broadband hologram with high tolerance to fabrication errors

    OpenAIRE

    Xiaohu Zhang; Jinjin Jin; Yanqin Wang; Mingbo Pu; Xiong Li; Zeyu Zhao; Ping Gao; Changtao Wang; Xiangang Luo

    2016-01-01

    With new degrees of freedom to achieve full control of the optical wavefront, metasurfaces could overcome the fabrication embarrassment faced by the metamaterials. In this paper, a broadband hologram using metasurface consisting of elongated nanoapertures array with different orientations has been experimentally demonstrated. Owing to broadband characteristic of the polarization-dependent scattering, the performance is verified at working wavelength ranging from 405 nm to 914 nm. Furthermore,...

  9. Offline Effects of Online Connecting: The Impact of Broadband Diffusion on Teen Fertility Decisions

    OpenAIRE

    Guldi, Melanie; Chris M. Herbst

    2015-01-01

    Broadband (high-speed) internet access expanded rapidly from 1999 to 2007. This expansion is associated with higher economic growth and labor market activity. In this paper, we examine whether the rollout also affected the social connections teens make. Specifically, we look at the relationship between increased broadband access and teen fertility. We hypothesize that increasing access to high-speed internet can influence fertility decisions by changing the size of the market as well as incre...

  10. Near-Field Broadband Beamformer Design via Multidimensional Semi-Infinite Linear Programming Techniques

    OpenAIRE

    Yiu, KFC; Yang, X.; Nordholm, S; Teo, KL

    2003-01-01

    Broadband microphone arrays has important applications such as hands-free mobile telephony, voice interface to personal computers and video conference equipment. This problem can be tackled in different ways. In this paper, a general broadband beamformer design problem is considered. The problem is posed as a Chebyshev minimax problem. Using the l1-norm measure or the real rotation theorem, we show that it can be converted into a semi-infinite linear programming problem. A numerical scheme us...

  11. Internet and broadband adoption in indigenous communities: An analysis of rural Alaska

    OpenAIRE

    Hudson, Heather E.

    2012-01-01

    Alaska is the largest state in the U.S., but with the nation's lowest population density of only 1.2 persons per square mile. About 15 percent of the population are Alaska Natives. Approximately two-thirds of this indigenous population live in more than 200 villages, most of which are remote settlements without road access. A current broadband infrastructure project in rural southwest Alaska provides an opportunity to gather reliable data on rural broadband adoption and use, and perceived bar...

  12. An Examination of the Evolution of Broadband Technologies in the UK

    OpenAIRE

    Deshpande, Advait

    2014-01-01

    The aim of this thesis is to examine the reasons due to which Digital Subscriber Line (DSL) became the most widely used technology to deliver broadband connectivity in the United Kingdom (UK). The research examines the outcome starting with events in 1960s when broadband as it is defined today did not exist. The research shows that a combination of factors involving regulatory decisions, changing market conditions, and unexpected technological breakthroughs contributed to the current day mix ...

  13. Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

    OpenAIRE

    The MAGIC Collaboration; Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.

    2014-01-01

    Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Aims. The goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These mechanisms may also apply to more distant blazars that cannot be studied with the same level of detail. Methods. A flare occurring in March 2010 ...

  14. Performance Analysis and Special Issues of Broadband Strategies in the Computer Communication

    OpenAIRE

    Dr.S.S.Riaz Ahamed; Dr.D.Mahesh

    2010-01-01

    Broadband communications consists of the technologies and equipment required to deliver packet-based digital voice, video, and data services to end users. Broadband affords end users high-speed, always-on access to the Internet while affording service providers the ability to offer value-added services to increase revenues. Due to the growth of the Internet, there has been tremendous buildout of high-speed, inter-city communications links that connect population centers and Internet service p...

  15. Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    OpenAIRE

    Washenfelder, R. A.; A. R. Attwood; Flores, J. M.; Rudich, Y.; S. S. Brown

    2015-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and ...

  16. Status of Broadband development in the Czech Republic and open issues

    Czech Academy of Sciences Publication Activity Database

    Kuchar, Anton

    Athens: BReATH Consortium, 2006, -. [Workshop Promoting Broadband Across Europe. Athens (GR), 04.09.2006] Grant ostatní: BReATH Consortium EU(XE) EC FP6 1ST Programme Institutional research plan: CEZ:AV0Z20670512 Keywords : telecommunication networks * broadband networks * Internet Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.ist-breath.net/events/eventE5.html

  17. Astigmatism-corrected Czerny-Turner imaging spectrometer for broadband spectral simultaneity

    International Nuclear Information System (INIS)

    A low-cost, broadband, astigmatism-corrected Czerny-Turner arrangement with a fixed plane grating is proposed. A wedge cylindrical lens is used to correct astigmatism over a broadband spectral range. The principle and method of astigmatism correction are described in detail. We compare the performance of this modified Czerny-Turner arrangement with that of the traditional Czerny-Turner arrangement by using a practical Czerny-Turner imaging spectrometer example.

  18. Astigmatism-corrected Czerny-Turner imaging spectrometer for broadband spectral simultaneity

    Energy Technology Data Exchange (ETDEWEB)

    Xue Qingsheng

    2011-04-01

    A low-cost, broadband, astigmatism-corrected Czerny-Turner arrangement with a fixed plane grating is proposed. A wedge cylindrical lens is used to correct astigmatism over a broadband spectral range. The principle and method of astigmatism correction are described in detail. We compare the performance of this modified Czerny-Turner arrangement with that of the traditional Czerny-Turner arrangement by using a practical Czerny-Turner imaging spectrometer example.

  19. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities.

    Science.gov (United States)

    Zhang, Xueqian; Tian, Zhen; Yue, Weisheng; Gu, Jianqiang; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2013-09-01

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. PMID:23787976

  20. Developing a marketing strategy for launching Intel-based mobile broadband dongles for the Russian market

    OpenAIRE

    Kasatkin, Dmitry

    2012-01-01

    The purpose of the study is to suggest a potential marketing strategy for launching Intel-based mobile broadband dongles for the Russian market. One objective is to identify what should be overall marketing strategy and another objective is to estimate potential demand for the Intel-based mobile broadband dongles. The conceptual framework is based on literature and articles about marketing strategies and consumer behavior. Concepts such as Marketing Mix (4Ps), Brand Image, Perceived Produc...

  1. Australia's project for universal broadband access: From policy to social potential

    OpenAIRE

    Dias, Marcos Pereira

    2012-01-01

    Australia’s National Broadband Network (NBN) aims to provide high–speed Internet broadband access to all Australians and transform Australia into one of the world’s top five digital economies by 2020. The NBN’s model of universal and equal access to information flows supported by a nationwide infrastructure network stands out from the dominant scenario of profit–driven, tiered models of communication infrastructure networks. This paper analyses the economic and s...

  2. Service Class Resource Management For Green Wireless-Optical Broadband Access NetworksWOBAN

    OpenAIRE

    Sruthy, S.; SUMI CHITRA K.A

    2015-01-01

    Abstract-Broadband access networks have become an essential part of worldwide communication systems because of the exponential growth of broadband services such as video on demand high definition TV internet protocol TV and video conferencing. Exponential growth in the volume of wireless data boosted by the growing popularity of mobile devices such as smartphone and tablets has forced the telecommunication industries to rethink the way networks are currently designed and to focus on the devel...

  3. Are Classroom Internet Use and Academic Performance Higher after Government Broadband Subsidies to Primary Schools?

    OpenAIRE

    Hyland, Marie; Layte, Richard; LYONS, SEAN; McCoy, Selina; Silles, Mary

    2015-01-01

    This paper combines data from a government programme providing broadband access to primary schools in Ireland with survey microdata on schools', teachers' and pupils use of the internet to examine the links between public subsidies, classroom use of the internet and educational performance. Provision of broadband service under a government scheme was associated with more than a doubling of teachers' use of the internet in class after about a two year lag. Better computing facilities in school...

  4. What drives and what hinders development of broadband in the Czech republic

    Czech Academy of Sciences Publication Activity Database

    Kuchar, Anton

    Geneve: BREAD , 2006, ---. [BroadBand Europe 2006. Geneve (CH), 11.12.2006-14.12.2006] Grant ostatní: BReATH Consortium EU(XE) EC FP6 1ST Programme Institutional research plan: CEZ:AV0Z20670512 Keywords : Internet * telecommunication networks * broadband networks Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.bbeurope.org, papers BB W1B-4

  5. The Use of PLC Technology in Broadband Services Offered to Households

    Directory of Open Access Journals (Sweden)

    Daniel Adamko

    2012-04-01

    Full Text Available The volume and quality of broadband services in any country is being understood not only as a major parameter related to the economic growth of that country, but also as a major parameter how much that country is ready for economic growth in the near future. With this understanding the main reasons why expansion of broadband services in Slovakia is an urgent issue are briefly outlined in this paper.

  6. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) – applicability and corrections

    OpenAIRE

    U. Platt; J. Meinen; D. Pöhler; T. Leisner

    2008-01-01

    Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broadband light sources, the broadband CEAS (BB-CEAS). BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light pa...

  7. Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

    OpenAIRE

    Varma, R. M.; Ball, S. M.; Brauers, T.; H.-P. Dorn; U. Heitmann; Jones, R L; U. Platt; D. Pöhler; A. A. Ruth; Shillings, A. J. L.; J. Thieser; A. Wahner; D. S. Venables

    2013-01-01

    Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three s...

  8. Examining Factors Influencing the Behavioral Intention to Adopt Broadband in Malaysia

    Science.gov (United States)

    Dwivedi, Yogesh K.; Selamat, Mohamad H.; Wahab, Muhammad S. Abd; Samsudin, Mohd A. Mat; Lal, Banita

    The aim of this study was to examine the factors affecting the adoption of broadband Internet in a developing country context by focusing upon Malaysia. The data relating to these factors was collected using a survey approach. The findings of this paper suggest that perceived usefulness, perceived ease of use, and social influence are significant factors for explaining the behavioral intention to adopt broadband Internet by Malaysian accountants. The paper proceeds to outline the research limitations, theoretical contributions, and implications for practice.

  9. Broadband terahertz generation using the semiconductor-metal transition in VO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Charipar, Nicholas A., E-mail: nicholas.charipar@nrl.navy.mil; Kim, Heungsoo; Mathews, Scott A.; Piqué, Alberto [Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, DC, 20375 (United States)

    2016-01-15

    We report the design, fabrication, and characterization of broadband terahertz emitters based on the semiconductor-metal transition in thin film VO{sub 2} (vanadium dioxide). With the appropriate geometry, picosecond electrical pulses are generated by illuminating 120 nm thick VO{sub 2} with 280 fs pulses from a femtosecond laser. These ultrafast electrical pulses are used to drive a simple dipole antenna, generating broadband terahertz radiation.

  10. Broadband Acoustic Liner Optimization Study Using Novel Poro-elastic Materials

    OpenAIRE

    Mitchell, Kelsey Ryan

    2015-01-01

    With the continual challenges associated with reducing aircraft engine noise, there is need for acoustic liner configurations that target broadband performance. This thesis experimentally and analytically investigates passive noise control methods to improve broadband frequency attenuation through various acoustic liner designs. The inclusion of acoustic metamaterials within these liners is examined and optimized. The metamaterials studied consist of resonant and non-resonant materials which ...

  11. Does Broadband Connectivity and Social networking sites build and maintain social capital in rural communities?

    OpenAIRE

    Tiwari, Sanjib; Lane, Michael; Alam, Khorshed

    2016-01-01

    Broadband internet access is a major enabling technology for building social capital (SC) by better connecting rural and regional communities which are often geographically dispersed both locally nationally and internationally. The main objectives of this paper were determine to what extent Social Networking Sites (SNS) can build SC for households in a rural and regional context of rural household adoption and use of broadband internet. A large scale survey of households was used to collect e...

  12. Information inequality and broadband network access: an analysis of Australian household data

    OpenAIRE

    Madden, Gary G; Savage, Scott J; Simpson, Michael

    1997-01-01

    There has been considerable debate in Australia concerning the social and economic effects of telecommunications carrier investment in broadband network infrastructure. Whether particular groups within networked communities are unable or unwilling to subscribe to broadband services is an important policy issue. This paper sets out to identify metropolitan households that are less likely to subscribe to services and examines whether there exists a systematic link between subscription interest ...

  13. RF Performance of Layer-Structured Broadband Passive Millimeter-Wave Imaging System

    OpenAIRE

    Kunio Sakakibara; Kunihiko Ohkawa; Yutaka Aoki; Nobuyoshi Kikuma

    2016-01-01

    Low profile and simple configuration are advantageous for RF module in passive millimeter-wave imaging system. High sensitivity over broad operation bandwidth is also necessary to detect right information from weak signal. We propose a broadband layer-structured module with low profile, simple structure, and ease of manufacture. This module is composed of a lens antenna and a detector module that consists of a detector circuit and a broadband microstrip-to-waveguide transition. The module for...

  14. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities

    KAUST Repository

    Zhang, Xueqian

    2013-06-21

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Proposition Analysis of Fixed Broadband Services Based on Product Segmentation and Purchasing Power of Urban Society

    OpenAIRE

    Triyono Budi Santoso

    2016-01-01

    Tight competition in the broadband industry has forced the provider to have a good product propotition and strategy in the market, including market segmentation and type of services delivered based on customers expextation and intention to buy. This research aims to make a product proposition based on two major criteries in fixed broadband service, which are speed and price of the product, by looking into the competition in existing market (competitors product). As many players in Indon...

  16. Global characterization of seismic noise with broadband seismometers

    CERN Document Server

    Coughlin, Michael William

    2012-01-01

    In this paper, we present an analysis of seismic spectra that were calculated from all broadband channels (BH?) made available through IRIS, NIED F-net and Orfeus servers covering the past five years and beyond. A general characterization of the data is given in terms of spectral histograms and data-availability plots. We show that the spectral information can easily be categorized in time and regions. Spectral histograms indicate that seismic stations exist in Africa, Australia and Antarctica that measure spectra significantly below the global low-noise models above 1 Hz. We investigate world-wide coherence between the seismic spectra and other data sets like proximity to cities, station elevation, earthquake frequency, and wind speeds. Elevation of seismic stations in the US is strongly anti-correlated with seismic noise near 0.2 Hz and again above 1.5 Hz. Urban settlements are shown to produce excess noise above 1 Hz, but correlation curves look very different depending on the region. It is shown that wind...

  17. Broadband sonar considerations for small underwater vehicle applications

    Science.gov (United States)

    Benjamin, Kim C.

    2003-10-01

    As underwater vehicles become more prevalent, so too does the design and integration of compact broadband sonar arrays. Rather than rely on conventional tonpilz technology, where the bandwidth is governed by the width of the transducer's mechanical resonance, designers must consider other transducer technologies that are better suited to small vehicle packaging constraints. These constraints include operational ruggedness, light weight, conformability, and low cost. This talk advocates the use of 1-3 piezocomposite and discusses the rationale behind such a selection. In going to a wideband material such as a 1-3 piezocomposite, with typical mechanical quality factors (Qm) around 2, the selection of where to place the resonance frequency differs from that of its tonpilz counterpart. For the tonpilz array, the sonar operational bandwidth is totally governed by the resonance response of the array element and is typically limited to approximately its 3-dB or half power points. Relaxor-based ferroelectric materials such as single crystal PMN-PT, which exhibit extremely large electromechanical coupling coefficients, cannot attain 3-dB bandwidths of a decade or more when configured in a tonpilz design. This presentation will discuss a 1-3 piezocomposite-based approach that places mechanical resonance near the upper band edge of an operational bandwidth of 1 decade (10-100 kHz).

  18. Broad-band study with Suzaku of the magnetar class

    CERN Document Server

    Enoto, Teruaki; Makishima, Kazuo; Rea, Nanda; Hurley, Kevein; Shibata, Shinpei

    2010-01-01

    Broad-band (0.8-70 keV) spectra of the persistent X-ray emission from 9 magnetars were obtained with Suzaku, including 3 objects in apparent outburst. The soft X-ray component was detected from all of them, with a typical blackbody temperature of kT ~ 0.5 keV, while the hard-tail component, dominating above ~10 keV, was detected at ~1 mCrab intensity from 7 of them. Therefore, the spectrum composed of a soft emission and a hard-tail component may be considered to be a common property of magnetars, both in their active and quiescent states. Wide-band spectral analyses revealed that the hard-tail component has a 1-60 keV flux, Fh, comparable to or even higher than that carried by the 1-60 keV soft component, Fs. The hardness ratio of these objects, defined as xi=Fh/Fs, was found to be tightly anti-correlated with their characteristic age tau as xi=(3.3+/-0.3)x(tau/1 kyr)^(-0.67+/-0.04) with a correlation coefficient of -0.989, over the range from xi~10 to xi~0.1. Magnetars in outburst states were found to lie o...

  19. Broadband PLC for Clustered Advanced Metering Infrastructure (AMI Architecture

    Directory of Open Access Journals (Sweden)

    Augustine Ikpehai

    2016-07-01

    Full Text Available Advanced metering infrastructure (AMI subsystems monitor and control energy distribution through exchange of information between smart meters and utility networks. A key challenge is how to select a cost-effective communication system without compromising the performance of the applications. Current communication technologies were developed for conventional data networks with different requirements. It is therefore necessary to investigate how much of existing communication technologies can be retrofitted into the new energy infrastructure to cost-effectively deliver acceptable level of service. This paper investigates broadband power line communications (BPLC as a backhaul solution in AMI. By applying the disparate traffic characteristics of selected AMI applications, the network performance is evaluated. This study also examines the communication network response to changes in application configurations in terms of packet sizes. In each case, the network is stress-tested and performance is assessed against acceptable thresholds documented in the literature. Results show that, like every other communication technology, BPLC has certain limitations; however, with some modifications in the network topology, it indeed can fulfill most AMI traffic requirements for flexible and time-bounded applications. These opportunities, if tapped, can significantly improve fiscal and operational efficiencies in AMI services. Simulation results also reveal that BPLC as a backhaul can support flat and clustered AMI structures with cluster size ranging from 1 to 150 smart meters.

  20. Upgrade to the Broadband Observation network for Lightning and Thunderstorms

    Science.gov (United States)

    Akiyama, Y.; Wu, T.; Stock, M.; Nakamura, Y.; Kikuchi, H.; Yoshida, S.; Ushio, T.; Kawasaki, Z.

    2015-12-01

    Observation sensors for lightning discharges sense electromagnetic waves, mainly in the ELF to UHF range, and especially in the LF and VHF bands. VHF band sensor sensors can observe lightning discharge process in detail but its observation coverage is limited. On the other hand, LF band sensor can observe lightning at much great distances. Therefore, LF sensors are well adapted to observe lightning throughout a thunderstorm's life cycle. Our research group has been designing and developing the Broadband Observation network for Lightning and Thunderstorm (BOLT), which locates radiation sources associated with lightning discharge in three spatial dimensions. BOLT consists of 11 LF band sensors which detect lightning pulses wide frequency range from 5 kHz to 500 kHz. We have been operating BOLT in Kansai area of Japan, locating both cloud-to-ground and intracloud discharges. Currently, the BOLT system observes about 100 to 1000 lightning pulses per flash, but we are striving to improve both the detection efficiency and the location accuracy. Preliminary investigation show that the number of sources located, increases dramatically when only the highest portion of the BLOT frequency band is used far location. So, our research group has proposed improving a new "DDT" antenna sensor design to improve the high frequency sensitivity of the antenna. The DDT antenna consists of a modified charge amplifier circuit. In this research, we present a comparison of the DDT antenna and show the advantages of the DDT antenna.

  1. Plasma wakefields driven by intense, broadband, incoherent electromagnetic radiation

    CERN Document Server

    Trines, R M G M; Mendonça, J T; Mori, W B; Norreys, P A; Bingham, R

    2014-01-01

    Non-linear wave-driven processes in plasmas are normally described by either a monochromatic pump wave that couples to other monochromatic waves, or as a random phase wave coupling to other random phase waves. An alternative approach involves an incoherent, random or broadband pump coupling to monochromatic and/or coherent structures in the plasma. This approach can be implemented through the wave kinetic model. In this model, the incoming pump wave is described by either a bunch (for coherent waves) or a sea (for random phase waves) of quasi-particles. A particle-in-cell type code has been developed to perform numerical simulations of such interactions using the quasi-particle approach. This code allows for a comparatively easy description of both random phase and coherent pump pulses coupling to slow electrostatic plasma waves, while providing an extended range of powerful diagnostics leading to a deeper physical insight into the dynamics of the fast waves. As an example, the propagation of short, intense l...

  2. Self-Organizing Maps on the Cell Broadband Engine Architecture

    International Nuclear Information System (INIS)

    We present and evaluate novel parallel implementations of Self-Organizing Maps for the Cell Broadband Engine Architecture. Motivated by the interactive nature of the data-mining process, we evaluate the scalability of the implementations on two clusters using different network characteristics and incarnations (PS3TMconsole and PowerXCell 8i) of the architecture. Our implementations use varying combinations of the Power Processing Elements (PPEs) and Synergistic Processing Elements (SPEs) found in the Cell architecture. For a single processor, our implementation scaled well with the number of SPEs regardless of the incarnation. When combining multiple PS3TMconsoles, the synchronization over the slower network resulted in poor speedups and demonstrated that the use of such a low-cost cluster may be severely restricted, even without the use of SPEs. When using multiple SPEs for the PowerXCell 8i cluster, the speedup grew linearly with increasing number of SPEs for a given number of processors, and linear up to a maximum with the number of processors for a given number of SPEs. Our implementation achieved a worst-case efficiency of 67% for the maximum number of processing elements involved in the computation, but consistently higher values for smaller numbers of processing elements with speedups of up to 70.

  3. Broadband Reflectionless Metasheets: Frequency-Selective Transmission and Perfect Absorption

    Science.gov (United States)

    Asadchy, V. S.; Faniayeu, I. A.; Ra'di, Y.; Khakhomov, S. A.; Semchenko, I. V.; Tretyakov, S. A.

    2015-07-01

    Energy of propagating electromagnetic waves can be fully absorbed in a thin lossy layer, but only in a narrow frequency band, as follows from the causality principle. On the other hand, it appears that there are no fundamental limitations on broadband matching of thin resonant absorbing layers. However, known thin absorbers produce significant reflections outside of the resonant absorption band. In this paper, we explore possibilities to realize a thin absorbing layer that produces no reflected waves in a very wide frequency range, while the transmission coefficient has a narrow peak of full absorption. Here we show, both theoretically and experimentally, that a thin resonant absorber, invisible in reflection in a very wide frequency range, can be realized if one and the same resonant mode of the absorbing array unit cells is utilized to create both electric and magnetic responses. We test this concept using chiral particles in each unit cell, arranged in a periodic planar racemic array, utilizing chirality coupling in each unit cell but compensating the field coupling at the macroscopic level. We prove that the concept and the proposed realization approach also can be used to create nonreflecting layers for full control of transmitted fields. Our results can have a broad range of potential applications over the entire electromagnetic spectrum including, for example, perfect ultracompact wave filters and selective multifrequency sensors.

  4. A broadband two axis flux-gate magnetometer

    Directory of Open Access Journals (Sweden)

    P. Palangio

    1998-06-01

    Full Text Available A broadband two axis flux-gate magnetometer was developed to obtain high sensitivity in magnetotelluric measurements. In magnetotelluric sounding, natural low frequency electromagnetic fields are used to estimate the conductivity of the Earth's interior. Because variations in the natural magnetic field have small amplitude(10-100 pT in the frequency range 1 Hz to 100 Hz, highly sensitive magnetic sensors are required. In magnetotelluric measurements two long and heavy solenoids, which must be installed, in the field station, perpendicular to each other (north-south and east-west and levelled in the horizontal plane are used. The coil is a critical component in magnetotelluric measurements because very slight motions create noise voltages, particularly troublesome in wooded areas; generally the installation takes place in a shallow trench. Moreover the coil records the derivative of the variations rather than the magnetic field variations, consequently the transfer function (amplitude and phase of this sensor is not constant throughout the frequency range 0.001-100 Hz. The instrument, developed at L'Aquila Geomagnetic Observatory, has a flat response in both amplitude and phase in the frequency band DC-100 Hz, in addition it has low weight, low power, small volume and it is easier to install in the field than induction magnetometers. The sensivity of this magnetometer is 10 pT rms.

  5. Photonics-based tunable and broadband radio frequency converter

    Science.gov (United States)

    Borges, Ramon Maia; Mazzer, Daniel; Rufino Marins, Tiago Reis; Sodré, Arismar Cerqueira

    2016-03-01

    This paper is regarding the concept and development of a photonics-based tunable and broadband radio frequency converter (PBRC). It employs an external modulation technique to generate and reconfigure its output frequency, a digital circuit to manage the modulators' bias voltages, and an optical interface for connecting it to optical-wireless networks based on radio-over-fiber technology. The proposed optoelectronic device performs photonics-based upconversion and downconversion as a function of the local oscillator frequency and modulators' bias points. Experimental results demonstrate a radiofrequency (RF) carrier conversion with spectral purity over the frequency range from 750 MHz to 6.0 GHz, as well as the integration of the photonics-based converter with an optical backhaul based on a 1.5-km single-mode fiber from a geographically distributed optical network. Low phase noise and distortion absence illustrate its applicability for convergent and reconfigurable optical wireless communications. A potential application relies on the use of PBRC in convergent optical wireless networks to dynamically provide RF carriers as a function of the telecom operator demand and radio propagation environment.

  6. Broadband Lg Attenuation Modeling in the Middle East

    Energy Technology Data Exchange (ETDEWEB)

    Pasyanos, M E; Matzel, E M; Walter, W R; Rodgers, A J

    2008-08-21

    We present a broadband tomographic model of Lg attenuation in the Middle East derived from source- and site-corrected amplitudes. Absolute amplitude measurements are made on hand-selected and carefully windowed seismograms for tens of stations and thousands of crustal earthquakes resulting in excellent coverage of the region. A conjugate gradient method is used to tomographically invert the amplitude dataset of over 8000 paths over a 45{sup o} x 40{sup o} region of the Middle East. We solve for Q variation, as well as site and source terms, for a wide range of frequencies ranging from 0.5-10 Hz. We have modified the standard attenuation tomography technique to more explicitly define the earthquake source expression in terms of the seismic moment. This facilitates the use of the model to predict the expected amplitudes of new events, an important consideration for earthquake hazard or explosion monitoring applications. The attenuation results have a strong correlation to tectonics. Shields have low attenuation, while tectonic regions have high attenuation, with the highest attenuation at 1 Hz is found in eastern Turkey. The results also compare favorably to other studies in the region made using Lg propagation efficiency, Lg/Pg amplitude ratios and two-station methods. We tomographically invert the amplitude measurements for each frequency independently. In doing so, it appears the frequency-dependence of attenuation is not compatible with the power law representation of Q(f), an assumption that is often made.

  7. Broadband Circular Polarizers Constructed by Helix-like Chiral Metamaterials

    CERN Document Server

    Ji, Ruonan; Liu, Xingxing; Chen, Xiaoshuang; Lu, Wei

    2016-01-01

    In this paper, a kind of helix-like chiral metamaterial, which can be realized with multiple conventional lithography or electron beam lithographic techniques, is proposed to achieve broadband bianisotropic optical response analogous to helical metamaterial. On the basis of twisted metamaterial, via tailoring the relative orientation within the lattice, the anisotropy of arc is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed to the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical response. For only a four-layer helix-like metamaterial, the maximum extinction ratio can reach 19.7. The operation band is in the wavelength range from 4.69 {\\mu}m to 8.98 {\\mu}m with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation...

  8. Broad-band solar bursts of the spike type

    International Nuclear Information System (INIS)

    Observations of high-resolution dynamic spectra of solar broad-band spike bursts (BSB), consisting of the instantaneous brightening of the continuum in the entire spectrograph range of 175-235 MHz, are reported. In noise storms events of the BSB type are rarely encountered and have the form of individual bursts with an average duration of 0.1-0.2 sec or groups of such bursts connected with type III bursts at lower frequencies. Series of aperiodic BSB structures unconnected with type III bursts and observed together with one-second pulsations and fiber bursts, predominate in type IV bursts. In noise storms BSB bursts can be emitted by electrons accelerated instantaneously as a result of the reconnection of magnetic fields, both in a small source (about 10 to the 8th cm) with a broad velocity dispersion and in an extended source (about 5 x 10 to the 9th cm). Structures of the BSB type in type IV bursts may be the result of the scattering of Langmuir waves on whistlers in a large height range. 30 references

  9. Spike-type broad-band solar bursts

    International Nuclear Information System (INIS)

    High-resolution dynamical spectra of solar broad-band spike bursts (BSB) have been observed. They represent an instantaneous brightening of the continuum emission in the range 175-235 MHz. In the noise stoms the BSB-type events occur seldom and have the form of either individual bursts with the average lifetime of 0.1-0.2 s or the groups of such bursts, related with type 3 bursts at lower frequencies. In type 4 bursts, the series of nonperiodic structures of BSB predominate. They are not related with type 3 bursts, but are observed together with the second pulsations and fiber bursts. In the noise storms, the BSB can be excited by electrons instantaneously accelerated owing to the magnetic field reconnection. The group delay leads to a negative frequency drift approximately -600 MHz/s in small sources and positive drift approximately 300 MHz/s in the extended ones. Such a high drift velocity cannot compensate the moderate frequency drift associated with the exciter motion in the corona. The BSB-structure in type 4 bursts can be the result of scattering of the Langmuir waves on the whistlers in a large height interval

  10. Broad-band solar bursts of the spike type

    Energy Technology Data Exchange (ETDEWEB)

    Bakunin, L.M.; Chernov, G.P.

    1985-10-01

    Observations of high-resolution dynamic spectra of solar broad-band spike bursts (BSB), consisting of the instantaneous brightening of the continuum in the entire spectrograph range of 175-235 MHz, are reported. In noise storms events of the BSB type are rarely encountered and have the form of individual bursts with an average duration of 0.1-0.2 sec or groups of such bursts connected with type III bursts at lower frequencies. Series of aperiodic BSB structures unconnected with type III bursts and observed together with one-second pulsations and fiber bursts, predominate in type IV bursts. In noise storms BSB bursts can be emitted by electrons accelerated instantaneously as a result of the reconnection of magnetic fields, both in a small source (about 10 to the 8th cm) with a broad velocity dispersion and in an extended source (about 5 x 10 to the 9th cm). Structures of the BSB type in type IV bursts may be the result of the scattering of Langmuir waves on whistlers in a large height range. 30 references.

  11. Theory for broadband detection of ion cyclotron resonance signals

    Science.gov (United States)

    McIver, Robert T.; Ledford, Edward B.; Hunter, Richard L.

    1980-02-01

    A complete line shape theory is developed for the transient response of a new type of ion cyclotron resonance (ICR) detector circuit. The detector is basically a balanced capacitance bridge which is sensitive to the abundance of gaseous ions stored in a static magnetic ion trap. For the first time, the equations of motion of ions in the ICR analyzer cell are shown to be coupled to the circuit equations of the detector. Also, the effect of nonreactive ion-molecule collisions on line shapes and on the transient response of the detector are analyzed and shown to allow measurement of ion-molecule collisions frequencies as a function of ion translational energy. One of the most important features of the capacitance bridge detector is its broadband sensitivity to a wide range of ion cyclotron resonance frequencies. This allows a mass spectrum of ions stored in the ICR analyzer cell to be obtained by scanning the frequency ω1 of the irradiating rf electric field at a fixed magnetic field strength. The capacitance bridge circuit can serve not only as a direct replacement for marginal oscillator circuits traditionally used in ICR experiments, but also as the detector for recently developed Fourier Transform and Rapid Scan ICR experiments.

  12. Transfer function of FBS-3A feedback broadband seismometer

    Institute of Scientific and Technical Information of China (English)

    刘庆伟; 庄灿涛; 刘慧宁

    2001-01-01

    FBS-3A feedback broadband seismometer has been widely utilized in observation networks up to now. There-fore, it is very important and practically meaningful for the application of this kind of sensor to fulfill some relative research work about its transfer function and for the analysis to the data recorded and the further devel-opment of the seismometer. In this paper, from the viewpoint of achieving its working principle, method of systematic analysis is applied to deduce the transfer functions, including both the transfer function for calibra-tion and that for measurement. Moreover, on the basis of that, the distribution of its zeroes and poles in a com-plex frequency domain is analyzed, which provides a convincing evidence to simplify this seismometer system from a high-order one to a two-order one. And the emulation of the frequency characteristics of FBS-3A is pre-sented in this paper. On the whole, the aim of this article is to do some theoretical work about the earthquake observation sensor, and also to introduce the method of making systematic analysis in a complex frequency domain to the research and the development of the seismometers.

  13. An omnidirectional broadband mirror design inspired by biological multilayer reflectors

    Science.gov (United States)

    Jordan, T. M.; Roberts, N. W.; Partridge, J. C.

    2012-04-01

    Biological multilayer reflectors are common in nature and some are able to reflect light across a broad range of wavelengths with a low degree of polarization over all angles of incidence. This inspired us to examine theoretically possible mechanisms that would allow stacks of biological materials to produce broadband omnidirectional reflections. Through the application of anisotropic multilayer theory, we establish that the degree of polarization of light reflected from the structure can be neutralized by birefringent layers with variations in the orientation of their optics axis and random variations in their optical thickness. The degree of polarization of reflected light decreases with the number of crystal layers and can be made arbitrarily low to produce true omnidirectional reflection. We also show that systematic variation in orientation and layer thickness can produce the same effect. This reflective structure is distinct from existing omnidirectional mirrors and can produce omnidirectional reflection even if the refractive index of the external environment is same as the low index isotropic layers.

  14. Broadband Vibrational Cooling of Cold Cesium Molecules: Theory and Experiments

    Institute of Scientific and Technical Information of China (English)

    D. Sofikitis; A. Fioretti; S. Weber; M. Viteau; A. Chotia; R. Horchani; M. Allegrini; B. Chatel; D. Comparat; P. Pillet

    2009-01-01

    The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample of cold molecules, initially distributed over several vibrational levels, has thus been transfered into a single selected vibrational level of the singlet X1∑g ground electronic state. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. In this paper we briefly report the main experimental results and then address, in a detailed way by computer simulations, the perspectives for a "complete" cooling of the molecules, including also the rotational degree of freedom. Since the pumping process strongly depends on the rclative shape of the ground and excited potential curves, ro-vibrational cooling through different excited states is theoretically compared.

  15. Nonperiodic metallic gratings transparent for broadband terahertz waves

    Science.gov (United States)

    Fan, Ren-Hao; Ren, Xiao-Ping; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    Recently, we demonstrate both theoretically and experimentally that nonperiodic metallic gratings can become transparent for broadband terahertz waves. Quasiperiodic and disordered metallic gratings effectively weaken and even eliminate Wood's anomalies, which are the diffraction-related characters of periodic gratings. Consequently, both the transparence bandwidth and transmission efficiency are significantly increased due to the structural aperiodicity. Furthermore, we show that for a specific light source, for example, a line source, a corresponding nonperiodic transparent grating can be also designed. We expect that our findings can be applied for transparent conducting panels, perfect white-beam polarizers, antireflective conducting solar cells, and beyond. References: X. P. Ren, R. H. Fan, R. W. Peng, X. R. Huang, D. H. Xu, Y. Zhou, and Mu Wang, Physical Review B, 91, 045111 (2015); R. H. Fan, R. W. Peng, X. R. Huang, J. Li, Y. Liu, Q. Hu, Mu. Wang, and X. Zhang, Advanced Materials, 24, 1980 (2012); and X. R. Huang, R. W. Peng, and R. H. Fan. Physical Review Letters, 105, 243901 (2010).

  16. Amorphous photonic membranes for broadband chemical sensing applications

    Science.gov (United States)

    Abbey, Sonja P.; Whaley, Ralph D., Jr.

    2012-01-01

    While there has been extensive development on integrated sensors in the near-IR region due to the maturation of Si, SOI, and III-V materials, these technologies are not easily translated into the visible and near-UV regions which are critical for the detection of many chemicals of environmental and security interest. This work focuses on the use of wide bandgap, amorphous materials, specifically, amorphous zinc oxide (a-ZnO), amorphous hafnium oxide (a-HfO2) and amorphous beryllium zinc oxide (a-BeZnO), in the development of broadband chemical sensors operating at critical absorption lines spanning the near-UV (200 nm) to the near-IR (1.55 μm). The architecture employed for this research is a nanoscale membrane (typically 40 - 100 nm thick) that supports a guided low optical overlap mode (LOOM) - an optical mode in which approximately 1% of the electric field is confined to the lossy core region. The resulting extended mode has a greatly enhanced analyte overlap, yielding a device sensitivity (~70%) that is over an order of magnitude higher than current high-performance, dielectric evanescent wave sensors (~2%) as modeled by analytical and finite element methods. Due to the extended nature of the LOOM, sensing across the entire spectral range can be achieved with a single waveguide design - critical for multi-point chemical sensing architectures.

  17. Speech recognition systems on the Cell Broadband Engine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y; Jones, H; Vaidya, S; Perrone, M; Tydlitat, B; Nanda, A

    2007-04-20

    In this paper we describe our design, implementation, and first results of a prototype connected-phoneme-based speech recognition system on the Cell Broadband Engine{trademark} (Cell/B.E.). Automatic speech recognition decodes speech samples into plain text (other representations are possible) and must process samples at real-time rates. Fortunately, the computational tasks involved in this pipeline are highly data-parallel and can receive significant hardware acceleration from vector-streaming architectures such as the Cell/B.E. Identifying and exploiting these parallelism opportunities is challenging, but also critical to improving system performance. We observed, from our initial performance timings, that a single Cell/B.E. processor can recognize speech from thousands of simultaneous voice channels in real time--a channel density that is orders-of-magnitude greater than the capacity of existing software speech recognizers based on CPUs (central processing units). This result emphasizes the potential for Cell/B.E.-based speech recognition and will likely lead to the future development of production speech systems using Cell/B.E. clusters.

  18. Model rotor low frequency broadband noise at moderate tip speeds

    Science.gov (United States)

    Humbad, N. G.; Harris, W. L.

    1980-01-01

    The results of an experimental investigation of low frequency broadband noise (LFBN) radiated from model helicopter rotors are presented. The results are for a range of tip Mach numbers (Mt) up to 0.50. The effect of rotor blade loading, advance ratio, tip speed, number of blades and free stream turbulence on the sound pressure level (SPL) and the spectrum of LFBN have been investigated. The peak SPL of LFBN appears to follow an M(4) law if the effect of rms turbulence velocity is removed. The peak SPL of LFBN seems to saturate with increases in advance ratio and with blade loading, and is proportional to the square of the turbulence integral scale when the effect of rms turbulence velocity and Mt are removed. Also, a simple peak SPL scaling law for noise from a helicopter rotor in forward flight due to convected sinusoidal gust is developed. The trend predicted by this scaling law is found to be satisfactory for the variation of the peak SPL of LFBN with tip speed.

  19. Optimization of broadband omnidirectional antireflection coatings for solar cells

    CERN Document Server

    Guo, Xia; Li, Chong; Zhou, Hongyi; Lv, Benshun; Feng, Yajie; Wang, Huaqiang; Liu, Wuming

    2015-01-01

    Broadband and omnidirectional antireflection coating is a generally effective way to improve solar cell efficiency, because the destructive interference between the reflected and input waves could maximize transmission light in the absorption layer. Several theoretical calculations have been developed to optimize the anti-reflective coating to maximize the average transmittance. However, the solar irradiances of the clear sky spectral direct beam on a receiver plane at different positions and times are variable greatly. Here we report a new theoretical calculation of anti-reflective coating with incident quantum efficiency {\\eta}in as evaluation function for practical application. The two-layer and three-layer anti-reflective coatings are optimized over {\\lambda} = [300, 1100] nm and {\\theta} = [0{\\deg}, 90{\\deg}] for cities of Quito, Beijing and Moscow. The {\\eta}in of two-layer anti-reflective coating increases by 0.26%, 1.37% and 4.24% for these 3 cities, respectively, compared with that other theoretical ...

  20. Broadband metasurface holograms: toward complete phase and amplitude engineering.

    Science.gov (United States)

    Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Gu, Jianqiang; Li, Yanfeng; Tian, Zhen; Singh, Ranjan; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2016-01-01

    As a revolutionary three-dimensional imaging technique, holography has attracted wide attention for its ability to photographically record a light field. However, traditional phase-only or amplitude-only modulation holograms have limited image quality and resolution to reappear both amplitude and phase information required of the objects. Recent advances in metasurfaces have shown tremendous opportunities for using a planar design of artificial meta-atoms to shape the wave front of light by optimal control of both its phase and amplitude. Inspired by the concept of designer metasurfaces, we demonstrate a novel amplitude-phase modulation hologram with simultaneous five-level amplitude modulation and eight-level phase modulation. Such a design approach seeks to turn the perceived disadvantages of the traditional phase or amplitude holograms, and thus enable enhanced performance in resolution, homogeneity of amplitude distribution, precision, and signal-to-noise ratio. In particular, the unique holographic approach exhibits broadband characteristics. The method introduced here delivers more degrees of freedom, and allows for encoding highly complex information into designer metasurfaces, thus having the potential to drive next-generation technological breakthroughs in holography. PMID:27615519