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Sample records for high-q whispering gallery

  1. Universal nonlinear scattering in ultra-high Q whispering gallery-mode resonators.

    Science.gov (United States)

    Lin, Guoping; Diallo, Souleymane; Dudley, John M; Chembo, Yanne K

    2016-06-27

    Universal nonlinear scattering processes such as Brillouin, Raman, and Kerr effects are fundamental light-matter interactions of particular theoretical and experimental importance. They originate from the interaction of a laser field with an optical medium at the lattice, molecular, and electronic scale, respectively. These nonlinear effects are generally observed and analyzed separately, because they do not often occur concomitantly. In this article, we report the simultaneous excitation of these three fundamental interactions in mm-size ultra-high Q whispering gallery mode resonators under continuous wave pumping. Universal nonlinear scattering is demonstrated in barium fluoride and strontium fluoride, separately. We further propose a unified theory based on a spatiotemporal formalism for the understanding of this phenomenology.

  2. Low-threshold stimulated Brillouin scattering in high-Q whispering gallery mode tellurite microspheres.

    Science.gov (United States)

    Guo, Changlei; Che, Kaijun; Zhang, Pan; Wu, Jinshu; Huang, Yantang; Xu, Huiying; Cai, Zhiping

    2015-12-14

    We demonstrate the first observation of stimulated Brillouin scattering (SBS) in a high-Q whispering gallery mode tellurite microsphere. Tellurite glass with composition of 70TeO₂-20ZnO-5Na₂O-5La₂O₃ (molar ratio) was prepared in-house using a melt-quenching technique. Moreover, tellurite microspheres with Q in excess of 13 millions at 1550 nm were fabricated by melting tellurite microwires using a CO₂ laser. By pumping the tellurite microspheres with a tunable single frequency laser, SBS is further realized with a threshold as low as 0.58 mW. At last, the beat notes between the pump and the Stokes signals were measured, which indicated the Brillouin frequency shift is at the 8.2 GHz band for our tellurite glass. Our results could propel significant applications utilizing SBS by employing tellurite microspheres.

  3. All-optical tunable buffering with coupled ultra-high Q whispering gallery mode microcavities.

    Science.gov (United States)

    Yoshiki, Wataru; Honda, Yoshihiro; Tetsumoto, Tomohiro; Furusawa, Kentaro; Sekine, Norihiko; Tanabe, Takasumi

    2017-09-06

    All-optical tunable buffering was recently achieved on a chip by using dynamically tuned coupled mode induced transparency, which is an optical analogue of electromagnetically induced transparency. However, the small Q s of about 105 used in those systems were limiting the maximum buffering time to a few hundred ps. Although employing an ultra-high Q whispering gallery mode (WGM) microcavity can significantly improve the maximum buffering time, the dynamic tuning of the WGM has remained challenging because thermo-optic and pressure tunings, which are widely used for WGM microcavities, have a very slow response. Here we demonstrate all-optical tunable buffering utilizing coupled ultra-high Q WGM cavities and the Kerr effect. The Kerr effect can change the refractive index instantaneously, and this allowed us to tune the WGM cavity very quickly. In addition, from among the various WGM cavities we employed a silica toroid microcavity for our experiments because it has an ultra-high Q factor (>2 × 107) and a small mode volume, and can be fabricated on a chip. Use of the Kerr effect and the silica toroid microcavity enabled us to observe an on-chip all-optical tunable buffering operation and achieve a maximum buffering time of 20 ns.

  4. Observation of energy oscillation between strongly-coupled counter-propagating ultra-high Q whispering gallery modes.

    Science.gov (United States)

    Yoshiki, Wataru; Chen-Jinnai, Akitoshi; Tetsumoto, Tomohiro; Tanabe, Takasumi

    2015-11-30

    We report the first experimental observation of an energy oscillation between two coupled ultra-high Q whispering gallery modes in the time domain. Two counter-propagating whispering gallery modes in a silica toroid microcavity were employed for this purpose. The combination of a large coupling coefficient between the two modes and an ultra-high Q factor, which creates a large Γ value of > 10, results in a clear energy oscillation. Our measurement is based on a drop-port measurement technique, which enables us to observe the light energy in the two modes directly. The oscillation period measured in the time domain precisely matched that inferred from mode splitting in the frequency domain, and the measured results showed excellent agreement with results calculated with the developed numerical model.

  5. Ultra-high Q whispering-gallery-mode bottle microresonators: properties and applications

    NARCIS (Netherlands)

    O'Shea, Danny; Junge, Christian; Nickel, Sebastian; Pöllinger, Michael; Rauschenbeutel, Arno; Kudryashov, Alexis V.; Paxton, Alan H.; Ilchenko, Vladimir S.

    2011-01-01

    Highly prolate-shaped whispering-gallery-mode "bottle microresonators" have recently attracted considerable attention due to their advantageous properties. We experimentally show that such resonators offer ultra-high quality factors, microscopic mode volumes, and near lossless in- and out-coupling

  6. High-Q MgF₂ whispering gallery mode resonators for refractometric sensing in aqueous environment.

    Science.gov (United States)

    Sedlmeir, Florian; Zeltner, Richard; Leuchs, Gerd; Schwefel, Harald G L

    2014-12-15

    We present our experiments on refractometric sensing with ultrahigh-Q, crystalline, birefringent magnesium fluoride (MgF₂) whispering gallery mode resonators. The difference to fused silica which is most commonly used for sensing experiments is the small refractive index of MgF₂ which is very close to that of water. Compared to fused silica this leads to more than 50% longer evanescent fields and a 4.25 times larger sensitivity. Moreover the birefringence amplifies the sensitivity difference between TM and TE type modes which will enhance sensing experiments based on difference frequency measurements. We estimate the performance of our resonators and compare them with fused silica theoretically and present experimental data showing the interferometrically measured evanescent field decay and the sensitivity of mm-sized MgF₂ whispering gallery mode resonators immersed in water. These data show reasonable agreement with the developed theory. Furthermore, we observe stable Q factors in water well above 1 × 10⁸.

  7. Adsorption detection for polylysine biomolecules based on high-Q silica capillary whispering gallery mode microresonator

    Science.gov (United States)

    Wu, Jixuan; Liu, Bo; Zhang, Hao; Song, Binbin

    2017-11-01

    A silica-capillary-based whispering gallery mode (WGM) microresonator has been proposed and experimentally demonstrated for the real-time monitoring of the polylysine adsorption process. The spectral characteristics of the WGM resonance dips with high quality factor and good wavelength selectivity have been investigated to evaluate the dynamic process for the binding of polylysine with a capillary surface. The WGM transmission spectrum shows a regular shift with increments of observation time, which could be exploited for the analysis of the polylysine adsorption process. The proposed WGM microresonator system possesses desirable qualities such as high sensitivity, fast response, label-free method, high detection resolution and compactness, which could find promising applications in histology and related bioengineering areas.

  8. Ultra-high Q whispering-gallery-mode bottle microresonators: properties and applications

    CERN Document Server

    O'Shea, D; Nickel, S; Poellinger, M; Rauschenbeutel, A; 10.1117/12.876790

    2011-01-01

    Highly prolate-shaped whispering-gallery-mode "bottle microresonators" have recently attracted considerable attention due to their advantageous properties. We experimentally show that such resonators offer ultra-high quality factors, microscopic mode volumes, and near lossless in- and out-coupling of light using ultra-thin optical fibers. Additionally, bottle microresonators have a simple and customizable mode structure. This enables full tunability using mechanical strain and simultaneous coupling of two ultra-thin coupling fibers in an add-drop configuration. We present two applications based on these characteristics: In a cavity quantum electrodynamics experiment, we actively stabilize the frequency of the bottle microresonator to an atomic transition and operate it in an ultra-high vacuum environment in order to couple single laser-cooled atoms to the resonator mode. In a second experiment, we show that the bottle microresonator can be used as a low-loss, narrow-band add-drop filter. Using the Kerr effect...

  9. Coupling single NV-centres to high-Q whispering gallery modes of a preselected frequency-matched microresonator

    Energy Technology Data Exchange (ETDEWEB)

    Schietinger, Stefan; Benson, Oliver [Nano-Optics, Institute of Physics, Humboldt-Universitaet zu Berlin, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)], E-mail: schietinger@physik.hu-berlin.de

    2009-06-14

    In this paper, we report the controlled coupling of fluorescence from a single NV-centre in a single nanodiamond to the high-Q modes of a preselected microsphere. Microspheres from an ensemble with a finite size distribution can be characterized precisely via white light Mie-scattering. The mode spectrum of individual spheres can be determined with high precision. A sphere with an appropriate spectrum can be selected, and a nanodiamond containing a single NV-centre can be coupled to it. The spectral position of the calculated lowest order whispering gallery modes are found to be in very good agreement with the experimentally observed resonances of the coupled fluorescence from the single NV-re.

  10. Refractometry-based air pressure sensing using glass microspheres as high-Q whispering-gallery mode microresonators

    Science.gov (United States)

    Bianchetti, Arturo; Federico, Alejandro; Vincent, Serge; Subramanian, Sivaraman; Vollmer, Frank

    2017-07-01

    In this work a refractometric air pressure sensing platform based on spherical whispering-gallery mode microresonators is presented and analyzed. The sensitivity of this sensing approach is characterized by measuring the whispering-gallery mode spectral shifts caused by a change of air refractive index produced by dynamic sinusoidal pressure variations that lie between extremes of ± 1.8 kPa . A theoretical frame of work is developed to characterize the refractometric air pressure sensing platform by using the Ciddor equation for the refractive index of air, and a comparison is made against experimental results for the purpose of performance evaluation.

  11. High-Q MgF$_2$ whispering gallery mode resonators for refractometric sensing in aqueous environment

    CERN Document Server

    Sedlmeir, Florian; Leuchs, Gerd; Schwefel, Harald G L

    2014-01-01

    We present our experiments on refractometric sensing with ultrahigh-Q, crystalline, birefringent magnesium fluoride (MgF$_2$) whispering gallery mode resonators. The difference to fused silica which is most commonly used for sensing experiments is the small refractive index of MgF$_2$ which is very close to that of water. Compared to fused silica this leads to more than 50% longer evanescent fields and a 4.25 times larger sensitivity. Moreover the birefringence amplifies the sensitivity difference between TM and TE type modes which will enhance sensing experiments based on difference frequency measurements. We estimate the performance of our resonators and compare them with fused silica theoretically and present experimental data showing the interferometrically measured evanescent decay and the sensitivity of mm-sized MgF$_2$ whispering gallery mode resonators immersed in water. They show reasonable agreement with the developed theory. Furthermore, we observe stable Q factors in water well above $1 \\times 10^...

  12. Test of the FDTD accuracy in the analysis of the scattering resonances associated with high-Q whispering-gallery modes of a circular cylinder.

    Science.gov (United States)

    Boriskin, Artem V; Boriskina, Svetlana V; Rolland, Anthony; Sauleau, Ronan; Nosich, Alexander I

    2008-05-01

    Our objective is the assessment of the accuracy of a conventional finite-difference time-domain (FDTD) code in the computation of the near- and far-field scattering characteristics of a circular dielectric cylinder. We excite the cylinder with an electric or magnetic line current and demonstrate the failure of the two-dimensional FDTD algorithm to accurately characterize the emission rate and the field patterns near high-Q whispering-gallery-mode resonances. This is proven by comparison with the exact series solutions. The computational errors in the emission rate are then studied at the resonances still detectable with FDTD, i.e., having Q-factors up to 10(3).

  13. Electro-optic modulation of high-Q lithium niobate whispering gallery resonator with integrated ground plane (Conference Presentation)

    Science.gov (United States)

    Douglas, Kenneth; Moore, Jeremy; Friedman, Thomas; Eichenfield, Matthew

    2017-02-01

    We experimentally demonstrate electro-optic modulation in thin film lithium niobate microdisk resonators with an integrated bottom electrode fabricated from a z-cut Lithium Niobate on Insulator wafer. The structure consisted of a 400nm thick crystalline z-cut lithium niobate/2um SiO2/20nm Cr/100nm Au/10nm Cr film stack on top of a z-cut lithium niobate handle wafer. The integrated bottom electrode is located 2um beneath the resonator. This proximity, coupled with positioning an electrical probe close to the top of the resonator, allows large optical frequency shifts with low voltages. We observed a 0.111pm/V resonance shift of vertically polarized (TM) optical whispering gallery modes, with the voltage applied perpendicular to the wafer surface. This corresponds to a shift of one optical linewidth at an applied voltage of 180V, using the r33 component of the eletro-optic tensor. We observed a smaller shift of 0.066pm/V for the radially polarized (TE) modes, using the r13 component of the electro-optic tensor. The experiment was performed using a 1550nm tunable laser that was coupled to the optical resonator modes using a tapered optical fiber. To measure the electro-optic shift of the resonance, a voltage was applied across the device via DC probe tips and the peak shift was calibrated with a Toptica WS6 IR wavemeter with 200 MHz absolute accuracy. We also present a finite element model that accurately predicts the resonance shift as a function of applied voltage for both polarizations.

  14. Whispering Gallery Mode Thermometry.

    Science.gov (United States)

    Corbellini, Simone; Ramella, Chiara; Yu, Lili; Pirola, Marco; Fernicola, Vito

    2016-10-29

    This paper presents a state-of-the-art whispering gallery mode (WGM) thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a sapphire-crystal-based whispering gallery mode resonator with the main resonant modes between 10 GHz and 20 GHz. In particular, it was found that the WGM around 13.6 GHz maximizes measurement performance, affording sub-millikelvin resolution and temperature stability of better than 1 mK at 0 °C. The thermometer system was made portable and low-cost by developing an ad hoc interrogation system (hardware and software) able to achieve an accuracy in the order of a few parts in 10⁸ in the determination of resonance frequencies. Herein we report the experimental assessment of the measurement stability, repeatability and resolution, and the calibration of the thermometer in the temperature range from -74 °C to 85 °C. The combined standard uncertainty for a single temperature calibration point is found to be within 5 mK (i.e., comparable with state-of-the-art for industrial thermometry), and is mainly due to the employed calibration setup. The uncertainty contribution of the WGM thermometer alone is within a millikelvin.

  15. Whispering Gallery Mode Thermometry

    Directory of Open Access Journals (Sweden)

    Simone Corbellini

    2016-10-01

    Full Text Available This paper presents a state-of-the-art whispering gallery mode (WGM thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a sapphire-crystal-based whispering gallery mode resonator with the main resonant modes between 10 GHz and 20 GHz. In particular, it was found that the WGM around 13.6 GHz maximizes measurement performance, affording sub-millikelvin resolution and temperature stability of better than 1 mK at 0 °C. The thermometer system was made portable and low-cost by developing an ad hoc interrogation system (hardware and software able to achieve an accuracy in the order of a few parts in 109 in the determination of resonance frequencies. Herein we report the experimental assessment of the measurement stability, repeatability and resolution, and the calibration of the thermometer in the temperature range from −74 °C to 85 °C. The combined standard uncertainty for a single temperature calibration point is found to be within 5 mK (i.e., comparable with state-of-the-art for industrial thermometry, and is mainly due to the employed calibration setup. The uncertainty contribution of the WGM thermometer alone is within a millikelvin.

  16. Whispering gallery mode sensors.

    Science.gov (United States)

    Foreman, Matthew R; Swaim, Jon D; Vollmer, Frank

    2015-06-30

    We present a comprehensive overview of sensor technology exploiting optical whispering gallery mode (WGM) resonances. After a short introduction we begin by detailing the fundamental principles and theory of WGMs in optical microcavities and the transduction mechanisms frequently employed for sensing purposes. Key recent theoretical contributions to the modeling and analysis of WGM systems are highlighted. Subsequently we review the state of the art of WGM sensors by outlining efforts made to date to improve current detection limits. Proposals in this vein are numerous and range, for example, from plasmonic enhancements and active cavities to hybrid optomechanical sensors, which are already working in the shot noise limited regime. In parallel to furthering WGM sensitivity, efforts to improve the time resolution are beginning to emerge. We therefore summarize the techniques being pursued in this vein. Ultimately WGM sensors aim for real-world applications, such as measurements of force and temperature, or alternatively gas and biosensing. Each such application is thus reviewed in turn, and important achievements are discussed. Finally, we adopt a more forward-looking perspective and discuss the outlook of WGM sensors within both a physical and biological context and consider how they may yet push the detection envelope further.

  17. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  18. Highly Efficient Integrated Generator of Tripartite Entanglement from χ (2) Whispering Gallery Microresonator

    Science.gov (United States)

    He, Guangqiang; Hu, Linxi; Li, Rongyu

    2017-08-01

    Whispering gallery microresonator (WGM) filled with nonlinear material has proven to be valuable for enhancing nonlinear optical effects. Here we explore the production of the pump-signal-idler tripartite entanglement based on the integrated high-Q whispering gallery mode cavities filled with lithium niobate. Our theoretical analysis about the entanglement condition when the van Loock and Furusawa criteria are violated paves the way for future investigation of integrated entanglement based on nonlinear high-Q microresonator. In addition, we present parameters used in our designed generator and our theoretical model is highly expansible to further exploration of entanglement over general χ (2) whispering gallery microresonator.

  19. Nanofabricated Optomechanical Whispering Gallery Mode Resonators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Strong interest in whispering gallery mode resonators (WGMR) for use in chip-scale photonic devices is motivated by their high optical quality, mechanical simplicity...

  20. Whispering-gallery-mode-based seismometer

    Science.gov (United States)

    Fourguette, Dominique Claire; Otugen, M Volkan; Larocque, Liane Marie; Ritter, Greg Aan; Meeusen, Jason Jeffrey; Ioppolo, Tindaro

    2014-06-03

    A whispering-gallery-mode-based seismometer provides for receiving laser light into an optical fiber, operatively coupling the laser light from the optical fiber into a whispering-gallery-mode-based optical resonator, operatively coupling a spring of a spring-mass assembly to a housing structure; and locating the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure so as to provide for compressing the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure responsive to a dynamic compression force from the spring-mass assembly responsive to a motion of the housing structure relative to an inertial frame of reference.

  1. Phone-sized whispering-gallery microresonator sensing system

    CERN Document Server

    Xu, Xiangyi; Zhao, Guangming; Yang, Lan

    2016-01-01

    We develop a compact whispering-gallery-mode (WGM) sensing system by integrating multiple components, including a tunable laser, a temperature controller, a function generator, an oscilloscope, a photodiode detector, and a testing computer, into a phone-sized embedded system. We demonstrate a thermal sensing experiment by using this portable system. Such a system successfully eliminates bulky measurement equipment required for characterizing optical resonators and will open up new avenues for practical sensing applications by using ultra-high Q WGM resonators.

  2. Nonlinear optics and crystalline whispering gallery mode resonators

    Science.gov (United States)

    Matsko, Andrey B.; Savchenkov, Anatoliy A.; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode (WGM) crystalline resonators, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics. In particular, we demonstrate experimentally a tunable third-order optical filter fabricated from the three metalized resonators; and report observation of parametric frequency dobuling in a WGM resonator made of periodically poled lithium niobate (PPLN).

  3. Optimized polaritonic modes in whispering gallery microcavities

    Science.gov (United States)

    Hu, Tao; Xie, Wei; Wu, Lin; Wang, Yafeng; Zhang, Long; Chen, Zhanghai

    2017-08-01

    We study both theoretically and experimentally the quality factor characteristic and the optimized polaritonic modes in a whispering gallery microcavity. The quality factors (Q-factors) of the resonant modes are determined by two main factors, i.e., the so called cavity loss and media loss. These two factors determine the final Q-factor and spontaneously lead to an optimized wavelength range for polariton modes. By using finite element analysis (FEA), we present the numerical simulation of resonant frequencies, field distributions and quality factors of the TE polarized whispering gallery modes (WGMs), which agree well with the experimental results. The control of optimized resonance in polaritonic system will be very useful for the development of semiconductor lasers with low threshold.

  4. Whispering gallery resonators for optical sensing

    Science.gov (United States)

    Madugani, Ramgopal; Kasumie, Sho; Yang, Yong; Ward, Jonathan; Lei, Fuchuan; Nic Chormaic, Síle

    2017-04-01

    In recent years, whispering gallery mode devices have extended their functionality across a number of research fields from photonics to sensing applications. Here, we will discuss environmental sensing applications, such as pressure, flow, and temperature using ultrahigh Q-factor microspheres fabricated from ultrathin optical fiber and microbubbles fabricated from pretapered glass capillary. We will discuss device fabrication and the different types of sensing that can be pursued using such systems. Finally, we will introduce the concept of using cavity ring-up spectroscopy to perform dispersive transient sensing, whereby a perturbation to the environment leads to a frequency mode shift, and dissipative transient sensing, which can lead to broadening of the mode, in a whispering gallery mode resonator.

  5. Naturally Phase-Matched Second-Harmonic Generation in a Whispering-Gallery-Mode Resonator

    DEFF Research Database (Denmark)

    Fürst, J. U.; Strekalov, D.V.; Elser, D.

    2010-01-01

    We demonstrate for the first time natural phase matching for optical frequency doubling in a high-Q whispering-gallery-mode resonator made of lithium niobate. A conversion efficiency of 9% is achieved at 30  μW in-coupled continuous wave pump power. The observed saturation pump power of 3.2 m...

  6. Feasibility of Passive Gas Sensor Based on Whispering Gallery Modes and its RADAR Interrogation: Theoretical and Experimental Investigations

    Directory of Open Access Journals (Sweden)

    Hamida HALLIL

    2010-05-01

    Full Text Available Feasibility of gas sensors based on Titanium Dioxide (TiO2 dielectric resonator operating with whispering-gallery modes is presented. The gas or humidity adsorption modifies the TiO2 dielectric permittivity and such modification induces variation in the resonant frequencies of high-Q whispering-gallery modes in the millimeter-wave frequency range. Full-wave electromagnetic simulation indicates that the measurement of this variation allows the derivation of few pars-per-million fluctuations in gas or humidity concentration. For validation purposes very first prototypes of resonator operating with whispering-gallery modes in the millimeter-wave frequency range are micro-machined. The obtained measured performances confirm that such high-Q resonant modes are very sensitive to small variations in dielectric resonator permittivity. Moreover we validate experimentally that these small variations can be remotely detected from the RADAR interrogation of an antenna loaded by the whispering-gallery modes resonator.

  7. Reconfigurable optical spectra from perturbations on elliptical whispering gallery resonances

    OpenAIRE

    Mohageg, Makan; Maleki, Lute

    2008-01-01

    Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbation is also observed.

  8. Full-vectorial whispering-gallery-mode cavity analysis.

    Science.gov (United States)

    Du, Xuan; Vincent, Serge; Lu, Tao

    2013-09-23

    We present a full-vectorial three-dimensional whispering-gallery-mode microcavity analysis technique. With this technique, optical properties such as resonance wavelength, quality factor, and electromagnetic field distribution of a microcavity in the presence of individual nanoparticle adsorption can be simulated with high accuracy, even in the presence of field distortion from plasmon effects at a wavelength close to plasmon resonance. This formulation is applicable to a wide variety of whispering-gallery related problems, such as waveguide to cavity coupling and full wave propagation analysis of a general whispering-gallery-mode microcavity where axisymmetry along the azimuthal direction is not required.

  9. Back-scatter based whispering gallery mode sensing

    National Research Council Canada - National Science Library

    Knittel, Joachim; Swaim, Jon D; McAuslan, David L; Brawley, George A; Bowen, Warwick P

    2013-01-01

    Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive real-time observation of motor molecule motion...

  10. Aptasensors Based on Whispering Gallery Mode Resonators.

    Science.gov (United States)

    Nunzi Conti, Gualtiero; Berneschi, Simome; Soria, Silvia

    2016-07-16

    In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR)-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON) ring resonators.

  11. Aptasensors Based on Whispering Gallery Mode Resonators

    Directory of Open Access Journals (Sweden)

    Gualtiero Nunzi Conti

    2016-07-01

    Full Text Available In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON ring resonators.

  12. Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

    Science.gov (United States)

    Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K.

    2013-01-01

    Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency. PMID:23963358

  13. Observation of whispering gallery modes through electron beam-induced deposition

    NARCIS (Netherlands)

    Timmermans, F. J.; Chang, L.; Van Wolferen, H. A.G.M.; Lenferink, A. T.M.; Otto, C.

    2017-01-01

    Surprisingly intense spectra of whispering gallery modes were observed in polymer microbeads after illumination with electrons in a scanning electron microscope and subsequent laser illumination and spectral analysis. It will be proposed that whispering gallery mode resonances became visible after

  14. Performance of Eudragit Coated Whispering Gallery Mode Resonator-Based Immunosensors

    Directory of Open Access Journals (Sweden)

    Franco Cosi

    2012-10-01

    Full Text Available Whispering gallery mode resonators (WGMR are an efficient tool for the realization of optical biosensors. A high Q factor preservation is a crucial requirement for good biosensor performances. In this work we present an Eudragit®L100 coated microspherical WGMR as an efficient immunosensor. The developed resonator was morphologically characterized using fluorescence microscopy. The functionalization process was tuned to preserve the high Q factor of the resonator. The protein binding assay was optically characterized in terms of specificity in buffer solution.

  15. Whispering gallery modes in deformed hexagonal resonators

    Energy Technology Data Exchange (ETDEWEB)

    Grundmann, Marius; Dietrich, Christof P. [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften, Institut fuer Experimentelle Physik II, Linnestr. 5, 04103 Leipzig (Germany)

    2012-05-15

    Optical resonances in polygonal resonators are due to whispering gallery modes (WGM). We investigate WGM in regular and deformed hexagonal ZnO microwire resonators. Four types of geometries are investigated: regular hexagonal and dodecagonal cross sections, hexagonal cross section elongated for one pair of facets and hexagonal cross section deformed by bending (uniaxial stress). Experimental data on mode energies and angular dispersion are correlated with model calculations and Poincare surfaces of section. Hexagonal ({phi} = 60 ), square ({phi} = 45 ), triangular ({phi} = 30 ), and Fabry-Perot modes ({phi} = 0 ) are observed in the various investigated geometries, {phi} being the angle of incidence at the facets with respect to the normal direction. Hexagonal WGMs (green, 6-WGM), triangular (red, 3-WGM), and double-triangular (blue, D3-WGM) rays in regular hexagons, elongated hexagons and hexagons deformed by bending. Triangular WGMs are stable modes in all three resonators. Hexagonal modes are not stable in the bent hexagon. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Reconfigurable Liquid Whispering Gallery Mode Microlasers.

    Science.gov (United States)

    Yang, Shancheng; Ta, Van Duong; Wang, Yue; Chen, Rui; He, Tingchao; Demir, Hilmi Volkan; Sun, Handong

    2016-06-03

    Engineering photonic devices from liquid has been emerging as a fascinating research avenue. Reconfigurably tuning liquid optical micro-devices are highly desirable but remain extremely challenging because of the fluidic nature. In this article we demonstrate an all-liquid tunable whispering gallery mode microlaser floating on a liquid surface fabricated by using inkjet print technique. We show that the cavity resonance of such liquid lasers could be reconfigurably manipulated by surface tension alteration originated from the tiny concentration change of the surfactant in the supporting liquid. As such, remarkable sensing of water-soluble organic compounds with a sensitivity of free spectral range as high as 19.85 THz / (mol · mL(-1)) and the detectivity limit around 5.56 × 10(-3) mol · mL(-1) is achieved. Our work provides not only a novel approach to effectively tuning a laser resonator but also new insight into potential applications in biological, chemical and environmental sensing.

  17. Ringing phenomenon based whispering-gallery-mode sensing.

    Science.gov (United States)

    Ye, Ming-Yong; Shen, Mei-Xia; Lin, Xiu-Min

    2016-01-22

    Highly sensitive sensing is one of the most important applications of whispering-gallery-mode (WGM) microresonators, which is usually accomplished through a tunable continuous-wave laser sweeping over a whispering-gallery mode with the help of a fiber taper in a relative slow speed. It is known that if a tunable continuous-wave laser sweeps over a high quality whispering-gallery mode in a fast speed, a ringing phenomenon will be observed. The ringing phenomenon in WGM microresonators is mainly used to measure the Q factors and mode-coupling strengths. Here we experimentally demonstrate that the WGM sensing can be achieved based on the ringing phenomenon. This kind of sensing is accomplished in a much shorter time and is immune to the noise caused by the laser wavelength drift.

  18. Liquid whispering-gallery-mode resonator as a humidity sensor.

    Science.gov (United States)

    Labrador-Páez, Lucía; Soler-Carracedo, Kevin; Hernández-Rodríguez, Miguel; Martín, Inocencio R; Carmon, Tal; Martin, Leopoldo L

    2017-01-23

    We experimentally demonstrate the high sensitivity of a novel liquid state, whispering-gallery-mode optical resonator to humidity changes. The optical resonator used consists of a droplet made of glycerol, a transparent liquid that enables high optical quality factor, doped with fluorescent material. As glycerol is highly hygroscopic, the refractive index and radius of the droplet change with ambient humidity. This produces a shift on the whispering gallery mode's wavelengths, which modulates the emission of the fluorescent material. This device shows an unpreceded sensitivity of 10-3 per relative humidity percent.

  19. Whispering gallery modes in silicon nanocrystal coated microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Bianucci, P.; Clements, C.; Meldrum, A. [Department of Physics, University of Alberta, Edmonton (Canada); Rodriguez, J.R.; Hessel, C.M.; Veinot, J.G.C. [Department of Chemistry, University of Alberta, Edmonton (Canada)

    2009-05-15

    We present photoluminescence studies of silicon-nanocrystal (Si-NC) coated microcavities. The particular geometries studied are hollow fibers where there is a Si-NC coating in the inner surface and regular optical fibers and glass microspheres where the coating is on the outside surface. The coatings were prepared using an inexpensive and straightforward solution-based process that yields a high-quality film. The measured photoluminescence spectra from the resonators show high Q-factor (between 1200 and 2800) resonant modes that correspond with the whispering gallery modes expected from the confinement geometries. The presence of these modes is also an indication that the emission of the Si-NCs is coupled to the cavity. The combination of Si-NCs and optical microcavities with strong confinement has promising potential for applications like sensing, optical communications and may be a possible route toward a Si-NC laser. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Controlled assembly of organic whispering-gallery-mode microlasers as highly sensitive chemical vapor sensors.

    Science.gov (United States)

    Gao, Miaomiao; Wei, Cong; Lin, Xianqing; Liu, Yuan; Hu, Fengqin; Zhao, Yong Sheng

    2017-03-09

    We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.

  1. Back-scatter based whispering gallery mode sensing.

    Science.gov (United States)

    Knittel, Joachim; Swaim, Jon D; McAuslan, David L; Brawley, George A; Bowen, Warwick P

    2013-10-17

    Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive real-time observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors.

  2. Whispering gallery modes in zinc oxide micro- and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Czekalla, Christian; Nobis, Thomas; Rahm, Andreas; Cao, Bingqiang; Zuniga-Perez, Jesus; Sturm, Chris; Schmidt-Grund, Ruediger; Lorenz, Michael; Grundmann, Marius [Institut fuer Experimentelle Physik II, Fakultaet fuer Physik und Geowissenschaften, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany)

    2010-06-15

    Optical whispering gallery mode (WGM) resonances have been observed in zinc oxide micro- and nanowire cavities. Using model calculations, the experimentally observed mode spectrum was reproduced. The effect has been observed for wire radii between 100 nm and 10 {mu}m corresponding to angular mode numbers from 1 to about 250. The whispering gallery effect was used to determine the refractive index of the wires as a function of the photon energy and temperature. Under high excitation conditions, WGM lasing was observed. Two methods for calculating the complex resonant modes are presented: a simple plane wave model and the numerical solution of the Helmholtz equation for the given resonator geometry. A typical photoluminescence (PL) spectrum showing WGM resonances and (inset) a scanning electron microscopy (SEM) image of a zinc oxide (ZnO) microwire. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  3. Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species

    OpenAIRE

    Anna Boleininger; Thomas Lake; Sophia Hami; Claire Vallance

    2010-01-01

    Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperat...

  4. Cylindrical Beam Propagation Modelling of Perturbed Whispering-Gallery Mode Microcavities

    OpenAIRE

    Shirazi, Mohammad Amin Cheraghi; Yu, Wenyan; Vincent, Serge; Lu, Tao

    2013-01-01

    We simulate light propagation in perturbed whispering-gallery mode microcavities using a two-dimensional finite-difference beam prop- agation method in a cylindrical coordinate system. Optical properties of whispering-gallery microcavities perturbed by polystyrene nanobeads are investigated through this formulation. The light perturbation as well as quality factor degradation arising from cavity ellipticity are also studied.

  5. Cylindrical beam propagation modelling of perturbed whispering-gallery mode microcavities.

    Science.gov (United States)

    Shirazi, Mohammad Amin Cheraghi; Yu, Wenyan; Vincent, Serge; Lu, Tao

    2013-12-16

    We simulate light propagation in perturbed whispering-gallery mode microcavities using a two-dimensional finite-difference beam propagation method in a cylindrical coordinate system. Optical properties of whispering-gallery microcavities perturbed by polystyrene nanobeads are investigated through this formulation. The light perturbation as well as quality factor degradation arising from cavity ellipticity are also studied.

  6. Broadband light-extraction enhanced by arrays of whispering gallery resonators

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Ou, Yiyu; Jokubavicius, Valdas

    2012-01-01

    We demonstrate a light-extraction approach using a whispering gallery resonators array. The wavelength-scale resonant dielectric nanospheres support whispering gallery modes, which can be coupled with the confined waveguide modes inside the bulk material, thus dramatically improving light...

  7. Whispering gallery modes in a spherical microcavity with a photoluminescent shell

    Energy Technology Data Exchange (ETDEWEB)

    Grudinkin, S. A., E-mail: grudink@gvg.ioffe.ru; Dontsov, A. A.; Feoktistov, N. A. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Baranov, M. A.; Bogdanov, K. V. [ITMO University (Russian Federation); Averkiev, N. S.; Golubev, V. G. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2015-10-15

    Whispering-gallery mode spectra in optical microcavities based on spherical silica particles coated with a thin photoluminescent shell of hydrogenated amorphous silicon carbide are studied. The spectral positions of the whispering-gallery modes for spherical microcavities with a shell are calculated. The dependence of the spectral distance between the TE and TM modes on the shell thickness is examined.

  8. Effects of whispering gallery mode in microsphere super-resolution imaging

    Science.gov (United States)

    Zhou, Song; Deng, Yongbo; Zhou, Wenchao; Yu, Muxin; Urbach, H. P.; Wu, Yihui

    2017-09-01

    Whispering Gallery modes have been presented in microscopic glass spheres or toruses with many applications. In this paper, the possible approaches to enhance the imaging resolution by Whispering Gallery modes are discussed, including evanescent waves coupling, transformed and illustration by Whispering Gallery modes. It shows that the high-order scattering modes play the dominant role in the reconstructed virtual image when the Whispering Gallery modes exist. Furthermore, we find that the high image resolution of electric dipoles can be achieved, when the out-of-phase components exist from the illustration of Whispering Gallery modes. Those results of our simulation could contribute to the knowledge of microsphere-assisted super-resolution imaging and its potential applications.

  9. Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism

    CERN Document Server

    Foreman, Matthew R; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical whispering gallery mode (WGM) resonators are a powerful and versatile tool used in many branches of science. Fine tuning of the central frequency and line width of individual resonances is however desirable in a number of applications including frequency conversion, optical communications and efficient light-matter coupling. To this end we present a detailed theoretical analysis of dielectric tuning of WGMs supported in axisymmetric resonators. Using the Bethe-Schwinger equation and adopting an angular spectrum field representation we study the resonance shift and mode broadening of high $Q$ WGMs when a planar dielectric substrate is brought close to the resonator. Particular focus is given to use of a uniaxial substrate with an arbitrarily aligned optic axis. Competing red and blue resonance shifts ($\\sim 30$ MHz), deriving from generation of a near field material polarisation and back action from the radiation continuum respectively, are found. Anomalous resonance shifts can hence be observed depend...

  10. Effect of crystalline family and orientation on stimulated Brillouin scattering in whispering-gallery mode resonators.

    Science.gov (United States)

    Diallo, Souleymane; Aubry, Jean-Pierre; Chembo, Yanne K

    2017-11-27

    Ultra-high Q whispering-gallery mode resonators pumped by a continuous-wave laser are known to enhance stimulated Brillouin scattering when optimal resonance and phase-matching conditions are met. In crystalline resonators, this process depends critically on the crystal orientation and family, which impose the elastic constants defining the velocity of the acoustic waves. In this article, we investigate the effect of crystalline orientation and family on this velocity which is proportional to the Brillouin frequency down-shift. In particular, the study is based on the development of a model and numerical simulations of acoustic wave velocities that propagate along the periphery of four fluoride crystals, namely calcium, magnesium, lithium and barium fluoride. We find that depending on the crystal and its orientation, the frequency excursion around the Brillouin offset can vary from few tens of kHz to more than a GHz.

  11. Bi-material crystalline whispering gallery mode microcavity structure for thermo-opto-mechanical stabilization

    Directory of Open Access Journals (Sweden)

    Hiroki Itobe

    2016-05-01

    Full Text Available We fabricated a calcium fluoride (CaF2 whispering gallery mode (WGM microcavity with a computer controlled ultra-precision cutting process. We observed a thermo-opto-mechanical (TOM oscillation in the CaF2 WGM microcavity, which may influence the stability of the optical output when the cavity is employed for Kerr comb generation. We studied experimentally and numerically the mechanism of the TOM oscillation and showed that it is strongly dependent on cavity diameter. In addition, our numerical study suggests that a microcavity structure fabricated with a hybrid material (i.e. CaF2 and silicon, which is compatible with an ultra-high Q and high thermal conductivity, will allow us to reduce the TOM oscillation and stabilize the optical output.

  12. All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators

    CERN Document Server

    O'Shea, D; Poellinger, M; Vogler, A; Rauschenbeutel, A

    2011-01-01

    We review our recent work on tunable, ultrahigh quality factor whispering-gallery-mode bottle microresonators and highlight their applications in nonlinear optics and in quantum optics experiments. Our resonators combine ultra-high quality factors of up to Q = 3.6 \\times 10^8, a small mode volume, and near-lossless fiber coupling, with a simple and customizable mode structure enabling full tunability. We study, theoretically and experimentally, nonlinear all-optical switching via the Kerr effect when the resonator is operated in an add-drop configuration. This allows us to optically route a single-wavelength cw optical signal between two fiber ports with high efficiency. Finally, we report on progress towards strong coupling of single rubidium atoms to an ultra-high Q mode of an actively stabilized bottle microresonator.

  13. In-fiber Mach-Zehnder interferometer and sphere whispering gallery mode resonator coupling structure.

    Science.gov (United States)

    Shi, Leilei; Zhu, Tao; Huang, Dongmei; Liang, Chuancan; Liu, Min; Liang, Shibin

    2017-01-01

    An in-fiber Mach-Zehnder interferometer and sphere whispering gallery mode resonator coupling structure is demonstrated by femtosecond laser micromachining. Asymmetric spectra around the resonant wavelength of the whispering gallery cavities in different coupling states are experimentally observed. An extinction ratio of ∼7  dB and a slope of 117 dB/nm can be achieved in the asymmetric spectrum of the overcoupled whispering gallery cavity, where an additional π phase shift at the resonant wavelength is introduced to the Mach-Zehnder interferometer.

  14. Unidirectional ultraviolet whispering gallery mode lasing from floating asymmetric circle GaN microdisk

    Science.gov (United States)

    Zhu, G. Y.; Qin, F. F.; Guo, J. Y.; Xu, C. X.; Wang, Y. J.

    2017-11-01

    Floating asymmetric circle and circle GaN microdisks are fabricated by using standard semiconductor techniques. Unidirectional ultraviolet whispering gallery mode lasing results from floating asymmetric circle GaN microdisks under optical pumping conditions at room temperature. The characteristics of the unidirectional whispering gallery mode lasing, including the lasing emission direction, threshold, emission intensity, and lasing mode number, are studied. A 2D finite difference time domain simulation on optical field distribution confirmed the resonance mechanism of whispering gallery mode lasing. This work is crucial for enhancing collection efficiency and facilitating the coupling of the electronic and photonic devices.

  15. Surface plasmon-enhanced two-photon excited whispering-gallery modes ultraviolet laser from Zno microwire

    Directory of Open Access Journals (Sweden)

    Yunpeng Wang

    2017-11-01

    Full Text Available The two-photon excited UV laser with narrow line width and high Q value was obtained. The total internal reflection from the four side surfaces of the quadrilateral-ZnO microwire offered the whispering gallery mode (WGM resonant cavity. The UV emission, resonant mechanism, and laser mode characteristics were discussed in detail for this special type of micro-cavity. In addition, in order to enhance the power of the two-photon excited UV laser, the surface plasmon enhancement by the Au nanoparticles was also performed and explained well by the theory of the localized surface plasmon.

  16. Surface plasmon-enhanced two-photon excited whispering-gallery modes ultraviolet laser from Zno microwire

    Science.gov (United States)

    Wang, Yunpeng; Zhu, Gangbei; Mei, Jingjing; Tian, Cancan; Liu, Hongzhen; Wang, Fei; Zhao, Dongxu

    2017-11-01

    The two-photon excited UV laser with narrow line width and high Q value was obtained. The total internal reflection from the four side surfaces of the quadrilateral-ZnO microwire offered the whispering gallery mode (WGM) resonant cavity. The UV emission, resonant mechanism, and laser mode characteristics were discussed in detail for this special type of micro-cavity. In addition, in order to enhance the power of the two-photon excited UV laser, the surface plasmon enhancement by the Au nanoparticles was also performed and explained well by the theory of the localized surface plasmon.

  17. Two-photon excited whispering-gallery mode ultraviolet laser from an individual ZnO microneedle

    Science.gov (United States)

    Zhu, G. P.; Xu, C. X.; Zhu, J.; Lv, C. G.; Cui, Y. P.

    2009-02-01

    Wurtzite structural ZnO microneedles with hexagonal cross section were fabricated by vapor-phase transport method and an individual microneedle was employed as a lasing microcavity. Under excitation of a femtosecond pulse laser with 800 nm wavelength, the ultraviolet (UV) laser emission was obtained, which presented narrow linewidth and high Q value. The UV emission, resonant mechanism, and laser mode characteristics were discussed in detail. The results demonstrated that the UV laser originated from the whispering-gallery mode induced by two-photon absorption assisted by Rabi oscillation.

  18. The influence of the whispering gallery modes resonators shape on their sensitivity to the movement

    Science.gov (United States)

    Filatov, Yuri V.; Govorenko, Ekaterina V.; Kukaev, Alexander S.; Shalymov, Egor V.; Venediktov, Vladimir Yu.

    2017-05-01

    The optical whispering gallery modes resonators are axially symmetrical resonators with smooth edges, supporting the existence of the whispering gallery modes by the total internal reflection on the surface of the resonator. For today various types of such resonators were developed, namely the ball-shaped, tor-shaped, bottle-shaped, disk-shaped etc. The movement of whispering gallery modes resonators in inertial space causes the changes of their shape. The result is a spectral shift of the whispering gallery modes. Optical methods allow to register this shift with high precision. It can be used in particular for the measurement of angular velocities in inertial orientation and navigation systems. However, different types of resonators react to the movement on a miscellaneous. In addition, their sensitivity to movement can be changed when changing the geometric parameters of these resonators. This work is devoted to a research of these aspects.

  19. Whispering gallery mode emission from a composite system of J-aggregates and photonic microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Melnikau, Dzmitry; Savateeva, Diana [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); Rusakov, Konstantin I. [Department of Physics, Brest State Technical University, Brest 224017 (Belarus); Rakovich, Yury P., E-mail: Yury.Rakovich@ehu.es [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)

    2014-01-15

    We report on development and characterization of Whispering Gallery Modes spherical microcavities integrated with organic dye molecules in a J-aggregate state. The microcavities are studied using micro-photoluminescence spectroscopy, and fluorescence lifetime imaging confocal microscopy. Directional emission of light from the microcavity is also experimentally demonstrated and attributed to the photonic jets generated in the microsphere. -- Highlights: • Report on the development and characterization of hybrid system consisting of thin shell of J-aggregates and spherical Whispering Gallery Mode microcavity. • An investigation of spontaneous emission rate in the shell of J-aggregates integrated with a Whispering Gallery Mode cavity. • Demonstration of directional emission from Whispering Gallery Mode cavity with J-aggregates which is highly desirable functionality for both micro- and nano-scale cavities.

  20. Optical sensors based on whispering gallery modes in fluorescent microbeads: size dependence and influence of substrate

    National Research Council Canada - National Science Library

    Francois, Alexandre; Himmelhaus, Michael

    2009-01-01

    Whispering gallery modes in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing changes in the refractive index of the beads' environment by exposing...

  1. Active chiral control of GHz acoustic whispering-gallery modes

    Science.gov (United States)

    Mezil, Sylvain; Fujita, Kentaro; Otsuka, Paul H.; Tomoda, Motonobu; Clark, Matt; Wright, Oliver B.; Matsuda, Osamu

    2017-10-01

    We selectively generate chiral surface-acoustic whispering-gallery modes in the gigahertz range on a microscopic disk by means of an ultrafast time-domain technique incorporating a spatial light modulator. Active chiral control is achieved by making use of an optical pump spatial profile in the form of a semicircular arc, positioned on the sample to break the symmetry of clockwise- and counterclockwise-propagating modes. Spatiotemporal Fourier transforms of the interferometrically monitored two-dimensional acoustic fields measured to micron resolution allow individual chiral modes and their azimuthal mode order, both positive and negative, to be distinguished. In particular, for modes with 15-fold rotational symmetry, we demonstrate ultrafast chiral control of surface acoustic waves in a micro-acoustic system with picosecond temporal resolution. Applications include nondestructive testing and surface acoustic wave devices.

  2. Whispering-Gallery Mode Resonators for Detecting Cancer.

    Science.gov (United States)

    Pongruengkiat, Weeratouch; Pechprasarn, Suejit

    2017-09-13

    Optical resonators are sensors well known for their high sensitivity and fast response time. These sensors have a wide range of applications, including in the biomedical fields, and cancer detection is one such promising application. Sensor diagnosis currently has many limitations, such as being expensive, highly invasive, and time-consuming. New developments are welcomed to overcome these limitations. Optical resonators have high sensitivity, which enable medical testing to detect disease in the early stage. Herein, we describe the principle of whispering-gallery mode and ring optical resonators. We also add to the knowledge of cancer biomarker diagnosis, where we discuss the application of optical resonators for specific biomarkers. Lastly, we discuss advancements in optical resonators for detecting cancer in terms of their ability to detect small amounts of cancer biomarkers.

  3. All-polymer whispering gallery mode sensor system.

    Science.gov (United States)

    Petermann, Ann Britt; Varkentin, Arthur; Roth, Bernhard; Morgner, Uwe; Meinhardt-Wollweber, Merve

    2016-03-21

    Sensors based on whispering gallery modes have been extensively investigated with respect to their possible application as physical or biological sensors. Instead of using a single resonator, we use an all polymer resonator array as sensing element. A tunable narrowband laser is coupled into a PMMA plate serving as an optical wave guide. PMMA spheres are placed in the evanescent field on the surface of the plate. Due to small size variations, some spheres are in resonance at a given wavelength while others are not. We show that this device is well suited for the determination of an unknown wavelength or for temperature measurements. Moreover, we discuss several general aspects of the sensor concept such as the number and size of sensing elements which are necessary for a correct measurement result, or the maximum acceptable linewidth of the laser.

  4. Dispersion analysis of whispering gallery mode microbubble resonators.

    Science.gov (United States)

    Riesen, Nicolas; Zhang, Wen Qi; Monro, Tanya M

    2016-04-18

    This paper examines the opportunities existing for engineering dispersion in non-silica whispering gallery mode microbubble resonators, for applications such as optical frequency comb generation. More specifically, the zero dispersion wavelength is analyzed as a function of microbubble diameter and wall thickness for several different material groups such as highly-nonlinear soft glasses, polymers and crystalline materials. The zero dispersion wavelength is shown to be highly-tunable by changing the thickness of the shell. Using certain materials it is shown that dispersion equalization can be realized at interesting wavelengths such as deep within the visible or mid-infrared, opening up new possibilities for optical frequency comb generation. This study represents the first extensive analysis of the prospects of using non-silica microbubbles for nonlinear optics.

  5. Polarization-selective out-coupling of whispering gallery modes

    CERN Document Server

    Sedlmeir, Florian; Vogl, Ulrich; Zeltner, Richard; Schunk, Gerhard; Strekalov, Dmitry V; Marquardt, Christoph; Leuchs, Gerd; Schwefel, Harald G L

    2016-01-01

    Whispering gallery mode (WGM) resonators are an important building block for linear, nonlinear and quantum optical experiments. In such experiments, independent control of coupling rates to different modes can lead to improved conversion efficiencies and greater flexibility in generation of non-classical states based on parametric down conversion. In this work, we introduce a scheme which enables selective out-coupling of WGMs belonging to a specific polarization family, while the orthogonally polarized modes remain largely unperturbed. Our technique utilizes material birefringence in both the resonator and coupler such that a negative (positive) birefringence allows selective coupling to TE (TM) polarized WGMs. We formulate a new coupling condition suitable for describing the case where the refractive indices of the resonator and the coupler are almost the same, from which we derive the criterion for polarization-selective coupling. We experimentally demonstrate our proposed method using a lithium niobate di...

  6. Light scattering by magnons in whispering gallery mode cavities

    Science.gov (United States)

    Sharma, Sanchar; Blanter, Yaroslav M.; Bauer, Gerrit E. W.

    2017-09-01

    Brillouin light scattering is an established technique to study magnons, the elementary excitations of a magnet. Its efficiency can be enhanced by cavities that concentrate the light intensity. Here, we theoretically study inelastic scattering of photons by a magnetic sphere that supports optical whispering gallery modes in a plane normal to the magnetization. Magnons with low angular momenta scatter the light in the forward direction with a pronounced asymmetry in the Stokes and the anti-Stokes scattering strength, consistent with earlier studies. Magnons with large angular momenta constitute Damon-Eschbach modes which are shown to inelastically reflect light. The reflection spectrum contains either a Stokes or anti-Stokes peak, depending on the direction of the magnetization, a selection rule that can be explained by the chirality of the Damon-Eshbach magnons. The controllable energy transfer can be used to manage the thermodynamics of the magnet by light.

  7. Nonlinear and Quantum Optics with Whispering Gallery Resonators

    CERN Document Server

    Strekalov, Dmitry V; Matsko, Andrey B; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon was later realized to have a rather general nature, equally applicable to sound and all other waves, but in particular also to electromagnetic waves ranging from radio frequencies to ultraviolet light. Very high quality factors of optical WGM resonators persisting in a wide wavelength range, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

  8. Optical frequency conversion in silica-whispering-gallery-mode microspherical resonators.

    Science.gov (United States)

    Farnesi, D; Barucci, A; Righini, G C; Berneschi, S; Soria, S; Nunzi Conti, G

    2014-03-07

    High quality factor whispering-gallery-mode microresonators are ideally suited for nonlinear optical interactions. We analyze, experimentally and theoretically, a variety of χ((3)) nonlinear interactions in silica microspheres, consisting of third harmonic generation and Raman assisted third order sum-frequency generation in the visible. A tunable, room temperature, cw multicolor emission in silica microspherical whispering-gallery-mode microresonators has been achieved by controlling the cavity mode dispersion and exciting nonequatorial modes for efficient frequency conversion.

  9. Whispering galleries and the control of artificial atoms.

    Science.gov (United States)

    Forrester, Derek Michael; Kusmartsev, Feodor V

    2016-04-28

    Quantum computation using artificial-atoms, such as novel superconducting circuits, can be sensitively controlled by external electromagnetic fields. These fields and the self-fields attributable to the coupled artificial-atoms influence the amount of quantum correlation in the system. However, control elements that can operate without complete destruction of the entanglement of the quantum-bits are difficult to engineer. Here we investigate the possibility of using closely-spaced-linear arrays of metallic-elliptical discs as whispering gallery waveguides to control artificial-atoms. The discs confine and guide radiation through the array with small notches etched into their sides that act as scatterers. We focus on π-ring artificial-atoms, which can generate their own spontaneous fluxes. We find that the micro-discs of the waveguides can be excited by terahertz frequency fields to exhibit whispering-modes and that a quantum-phase-gate composed of π-rings can be operated under their influence. Furthermore, we gauge the level of entanglement through the concurrence measure and show that under certain magnetic conditions a series of entanglement sudden-deaths and revivals occur between the two qubits. This is important for understanding the stability and life-time of qubit operations using, for example, a phase gate in a hybrid of quantum technologies composed of control elements and artificial-atoms.

  10. Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species

    Directory of Open Access Journals (Sweden)

    Anna Boleininger

    2010-03-01

    Full Text Available Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperature, and its measurement capabilities are demonstrated through application to high-precision fibre geometry profiling and the detection of unlabelled biochemical species. The prototype sensor is capable of detecting unlabelled biomolecular species in attomole quantities.

  11. Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species

    Science.gov (United States)

    Boleininger, Anna; Lake, Thomas; Hami, Sophia; Vallance, Claire

    2010-01-01

    Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperature, and its measurement capabilities are demonstrated through application to high-precision fibre geometry profiling and the detection of unlabelled biochemical species. The prototype sensor is capable of detecting unlabelled biomolecular species in attomole quantities. PMID:22294898

  12. Whispering-Gallery modes dynamics of GaAs-AlGaAs microdisk lasers

    Science.gov (United States)

    Heberle, Albert; Zhang, Botao

    2009-03-01

    Semiconductor microdisk lasers are of great interest because of their low threshold, high Q-factor and potential for quantum optical effects. A microdisk laser consists of a disk with typically 100 nm thickness and several microns diameter freely standing on a pedestal. Total reflection induces high-Q whispering-gallery modes inside the circular outer edge of the disk-shaped cavity. We investigated the picoseconds dynamics of GaAs/AlGaAs microdisk lasers after ultrafast optical excitation at a sample temperature of 10 Kelvin. Surface recombination was prevented by passivation. The emission was measured temporally and spectrally resolved with a streak camera connected to a confocal microscope. The spatial emission patterns of the lasers varied significantly with the position of the exciting laser spot and shifted blue shift with increasing excitation power. The devices emitted in one or two optical modes with an excitation-dependent turn-on delay of the order of 15 picoseconds and a 5 meV red shift with two time constants during the typically 50 picosecond emission time. These effects show the balance between carrier cooling, diffusion and recombination in connection with band gap renormalization and refractive index changes

  13. Optofluidic whispering gallery mode microcapillary lasers for refractive index sensing

    Science.gov (United States)

    François, Alexandre; Riesen, Nicolas; Gardner, Kristy; Monro, Tanya M.; Meldrum, Al

    2016-12-01

    Whispering gallery modes (WGMs) allow for remarkable refractive index sensing performance with extremely low detection limits, and thus have found use in various emerging label free biosensing applications. Among the different types of resonators which have been studied, microcapillaries have the unique property of having the evanescent fields extend into and sample the medium inside the resonator, which is particularly interesting because the resonator itself serves as a microfluidic channel. Here, lasing of the WGMs in fluorescent microcapillaries is demonstrated for the first time, and their application to refractive index sensing is investigated. The laser gain medium used here is embedded inside a high refractive index polymer coating deposited onto the inner surface of the capillary. Lasing can only be realized for thick polymer coatings (in this case >= 800 nm), with higher Q factor but also stronger confinement of the propagating wave, which lowers the refractive index sensitivity compared to non-lasing capillaries which can have thinner polymer coatings. We however find that the large improvement in signal-to-noise ratio and Q factor realized upon lasing more than compensates for the reduced sensitivity, resulting in an order-of-magnitude improvement in the detection limit for refractive index sensing.

  14. Protein-based flexible whispering gallery mode resonators

    Science.gov (United States)

    Yilmaz, Huzeyfe; Pena-Francesch, Abdon; Xu, Linhua; Shreiner, Robert; Jung, Huihun; Huang, Steven H.; Özdemir, Sahin K.; Demirel, Melik C.; Yang, Lan

    2016-02-01

    The idea of creating photonics tools for sensing, imaging and material characterization has long been pursued and many achievements have been made. Approaching the level of solutions provided by nature however is hindered by routine choice of materials. To this end recent years have witnessed a great effort to engineer mechanically flexible photonic devices using polymer substrates. On the other hand, biodegradability and biocompatibility still remains to be incorporated. Hence biomimetics holds the key to overcome the limitations of traditional materials in photonics design. Natural proteins such as sucker ring teeth (SRT) and silk for instance have remarkable mechanical and optical properties that exceed the endeavors of most synthetic and natural polymers. Here we demonstrate for the first time, toroidal whispering gallery mode resonators (WGMR) fabricated entirely from protein structures such as SRT of Loligo vulgaris (European squid) and silk from Bombyx mori. We provide here complete optical and material characterization of proteinaceous WGMRs, revealing high quality factors in microscale and enhancement of Raman signatures by a microcavity. We also present a most simple application of a WGMR as a natural protein add-drop filter, made of SRT protein. Our work shows that with protein-based materials, optical, mechanical and thermal properties can be devised at the molecular level and it lays the groundwork for future eco-friendly, flexible photonics device design.

  15. Whispering-gallery mode resonators for highly unidirectional laser action

    Science.gov (United States)

    Wang, Qi Jie; Yan, Changling; Yu, Nanfang; Unterhinninghofen, Julia; Wiersig, Jan; Pflügl, Christian; Diehl, Laurent; Edamura, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi; Capasso, Federico

    2010-01-01

    Optical microcavities can be designed to take advantage of total internal reflection, which results in resonators supporting whispering-gallery modes (WGMs) with a high-quality factor (Q factor). One of the crucial problems of these devices for practical applications such as designing microcavity lasers, however, is that their emission is nondirectional due to their radial symmetry, in addition to their inefficient power output coupling. Here we report the design of elliptical resonators with a wavelength-size notch at the boundary, which support in-plane highly unidirectional laser emission from WGMs. The notch acts as a small scatterer such that the Q factor of the WGMs is still very high. Using midinfrared (λ ∼ 10 μm) injection quantum cascade lasers as a model system, an in-plane beam divergence as small as 6 deg with a peak optical power of ∼5 mW at room temperature has been demonstrated. The beam divergence is insensitive to the pumping current and to the notch geometry, demonstrating the robustness of this resonator design. The latter is scalable to the visible and the near infrared, thus opening the door to very low-threshold, highly unidirectional microcavity diode lasers. PMID:21149678

  16. Whispering Gallery Mode Dip Sensor for Aqueous Sensing.

    Science.gov (United States)

    Agarwal, Monica; Teraoka, Iwao

    2015-10-20

    We report fabrication of a 4 mm thick, preassembled whispering gallery mode (WGM) sensor that can be repeatedly dipped into aqueous solutions and lifted. We built the viable photonic sensor assembly by bending an optical fiber by 90° and molding its tip into a sphere, thus, a long stem holding a submillimeter sensor at the end of a short arm of fiber, and positioning a pair of parallel cone-tipped tapers along the long stem so that the tips touch the sensor. Our sensor head is an optical fiber device just a few millimeters thick and yet has a sensitivity of the resonance wavelength shift comparable to the one obtained with conventional WGM sensors in a planar arrangement. Since dipping and lifting from the solution changes the temperature of the sensor, affecting the resonance wavelength, we enclosed a thermistor within the sensor head to monitor the temperature. We demonstrate that the resonance shift in repeated transfer of the sensor head between water and a solution of sucrose, after correction by the temperature change, is reproducible and agrees with a theoretical estimate of the shift for different concentrations.

  17. Whispering gallery mode temperature sensor of liquid microresonastor.

    Science.gov (United States)

    Liu, Zhihai; Liu, Lu; Zhu, Zongda; Zhang, Yu; Wei, Yong; Zhang, Xiaonan; Zhao, Enming; Zhang, Yaxun; Yang, Jun; Yuan, Libo

    2016-10-15

    We propose and demonstrate a whispering gallery mode (WGM) resonance-based temperature sensor, where the microresonator is made of a DCM (2-[2-[4-(dimethylamino)phenyl] ethenyl]-6-methyl-4H-pyran-4-ylidene)-doped oil droplet (a liquid material) immersed in the water solution. The oil droplet is trapped, controlled, and located by a dual-fiber optical tweezers, which prevents the deformation of the liquid droplet. We excite the fluorescence and lasing in the oil droplet and measure the shifts of the resonance wavelength at different temperatures. The results show that the resonance wavelength redshifts when the temperature increases. The testing sensitivity is 0.377 nm/°C in the temperature range 25°C-45°C. The results of the photobleaching testing of the dye indicate that measured errors can be reduced by reducing the measured time. As far as we know, this is the first time a WGM temperature sensor with a liquid state microcavity has been proposed. Compared with the solid microresonator, the utilization of the liquid microresonator improves the thermal sensitivity and provides the possibility of sensing in liquid samples or integrating into the chemical analyzers and microfluidic systems.

  18. Interfacing whispering gallery mode microresonators for environmental biosensing

    Science.gov (United States)

    Hunt, Heather K.; Dahmen, Jeremy L.; Soteropulos, Carol E.

    2014-03-01

    Label-free biosensors that combine high sensitivity and high specificity characteristics have shown tremendous potential for applications in medical diagnostics, and have more recently been extended to the food safety and environmental monitoring arenas. A unique type of label-free, optical biosensor, based on Whispering Gallery Mode microresonators, has tremendous potential to revolutionize biodetection due to its extreme sensitivity. The primary limitation of these biosensors, however, is that they require the addition of biorecognition elements to specifically target a biological species of interest. Therefore, the ability to selectively functionalize the microresonator for a specific target molecule, without degrading device performance, is extremely important, and represents the next step in translating these devices from laboratory to field environments. Here, we demonstrate a variety of straightforward bioconjugation strategies that not only impart specificity to optical microresonators, but also allow for the creation of multi-use platforms for complex environments. Of particular interest is the ability to detect harmful bacteria, insects, and fungi in crop and water systems. The resulting surface chemistries are illustrated with XPS, SEM, and fluorescence and optical microscopy, and the device sensitivity is determined via quantitative microcavity analysis. The ability to minimize non-specific adsorption and target unique molecules in complex environments is demonstrated via ellipsometry and in situ device testing. The resulting devices can be recycled several times without loss of sensitivity. By combining these high sensitivity biosensors with appropriate biochemistries, the resulting platforms can be extended to address broader issues in environmental biosensing that directly impact agriculture.

  19. Accurate identification of whispering gallery mode patterns of gyrotron with stabilized electro-optic imaging system

    Science.gov (United States)

    Lee, Ingeun; Sawant, Ashwini; Choe, Mun Seok; Lee, Dong-Joon; Choi, EunMi

    2018-01-01

    The precise field pattern measurement and analysis of a typical whispering gallery mode excited in a gyrotron are important to understand the interaction physics of the gyrotron. We precisely analyzed the characteristic of a whispering gallery mode, rotating TE6,2 mode, by a photonic-assisted W-band (75-110 GHz) electro-optic imaging measurement system. The whispering gallery mode in the W-band region diverges fast in free space as it propagates from the radiation port. Therefore, scanning the field patterns of a device-under-test should be performed as close as possible to identify the device's characteristics. We successfully accomplished visualizing highly accurate field patterns of a rotating and mixed whispering gallery mode based on the measured electric field magnitude and phase by using dual optical fiber-scale electro-optic (EO) probes. We observed the distorted fields when the typical open-ended waveguide and a general EO probe were used in the extremely near-field zone, whereas a very precise field was measured in a minimally invasive way by the proposed EO probe. The measured mode patterns were quantitatively analyzed by using a cross correlation function and a mode purity equation. This work promises a way to provide accurate electric field information in the generation of the whispering gallery mode in the millimeter and submillimeter regime.

  20. Whispering gallery modes in a glass microsphere as a function of temperature.

    Science.gov (United States)

    Martín, L L; Pérez-Rodríguez, C; Haro-González, P; Martín, I R

    2011-12-05

    Microspheres of Nd3+ doped barium titano silicate glass were prepared and the whispering gallery mode resonances were observed in a modified confocal microscope. A bulk sample of the same glass was calibrated as temperature sensor by the fluorescence intensity ratio technique. After that, the microsphere was heated by laser irradiation process technique in the microscope and the surface temperature was estimated using the fluorescence intensity ratio. This temperature is correlated with the displacement of the whispering gallery mode peaks, showing an average red-shift of 10 pm/K in a wide range of surface temperatures varying from 300 K to 950K. The limit of resolution in temperature was estimated for the fluorescence intensity ratio and the whispering gallery mode displacement, showing an improvement of an order of magnitude for the second method.

  1. In-fiber whispering-gallery-mode resonator fabricated by femtosecond laser micromachining.

    Science.gov (United States)

    Shi, Leilei; Zhu, Tao; Huang, Dongmei; Liu, Min; Deng, Ming; Huang, Wei

    2015-08-15

    An in-fiber whispering-gallery-mode resonator fabricated by femtosecond laser micromachining is demonstrated. The cylinder resonator cavity is fabricated by scanning the D-fiber cladding with infrared femtosecond pulses along a cylindrical trace with a radius of 25 μm and height of 20 μm. Quality factor on the order of 10(3) is achieved by smoothing the cavity surface with an ultrasonic cleaner, which is mainly limited by the surface roughness of several hundred nanometers. Resonant characteristics and polarization dependence of the proposed resonator are also studied in detail. Our method takes a step forward in the integration of whispering-gallery-mode resonators.

  2. The influence of whispering gallery modes on the far field of ring lasers

    Science.gov (United States)

    Szedlak, Rolf; Holzbauer, Martin; MacFarland, Donald; Zederbauer, Tobias; Detz, Hermann; Andrews, Aaron Maxwell; Schwarzer, Clemens; Schrenk, Werner; Strasser, Gottfried

    2015-01-01

    We introduce ring lasers with continuous π-phase shifts in the second order distributed feedback grating. This configuration facilitates insights into the nature of the modal outcoupling in an optical cavity. The grating exploits the asymmetry of whispering gallery modes and induces a rotation of the far field pattern. We find that this rotation can be connected to the location of the mode relative to the grating. Furthermore, the direction of rotation depends on the radial order of the whispering gallery mode. This enables a distinct identification and characterization of the mode by simple analysis of the emission beam. PMID:26573341

  3. Integrating Whispering Gallery Mode Refractive Index Sensing with Capillary Electrophoresis Separations Using Phase Sensitive Detection.

    Science.gov (United States)

    Kim, Daniel C; Dunn, Robert C

    2016-01-19

    Whispering gallery mode (WGM) resonators are small, radially symmetric dielectrics that recirculate light through continuous total internal reflection. High-Q resonances are observed that shift in response to changes in surrounding refractive index, leading to many applications in label-free sensing. Surface binding measurements with WGM resonators have demonstrated competitive analytical detection metrics compared to other sensing schemes. Similar figures of merit for detecting bulk refractive index changes, however, have proven more challenging. This has limited their use in applications such as capillary electrophoresis (CE), where their compact footprint and refractive index sensitivity offers advantages in nondestructive, universal detection. Here we couple WGM detection with CE by introducing a modulation scheme to improve detection limits. Phase sensitive WGM (PS-WGM) detection is developed to monitor real-time shifts in the WGM spectrum due to changes in surrounding refractive index. We directly compare phase sensitive detection with spectral measurements normally used to track WGM shifts. We report an improvement in detection limits by almost 300-fold using the PS-WGM method. The integrated CE with PS-WGM approach is demonstrated by detecting the separation of a three-component mixture of cations (Na(+), Li(+), and K(+)).

  4. Investigation of a shift of whispering-gallery modes caused by deformations and tensions

    Science.gov (United States)

    Filatov, Yuri Vladimirovich; Kukaev, Alexander Sergeevich; Shalymov, Egor Vadimovich; Venediktov, Vladimir Yurievich

    2017-10-01

    The influence of centrifugal forces on angular velocity sensors that measure a spectral shift of whispering-gallery modes (WGMs) is investigated. Spherical WGM resonators of different materials are considered the sensing elements. The study is based on the results of the simulation in OOFELIE::Multiphysics software.

  5. All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators

    NARCIS (Netherlands)

    O'Shea, D.; Junge, C.; Poellinger, M.; Vogler, A.; Rauschenbeutel, A.

    2011-01-01

    We review our recent work on tunable, ultra-high quality factor whispering-gallery-mode bottle microresonators and highlight their applications in non-linear optics and in quantum optics experiments. Our resonators combine ultra-high quality factors of up to Q=3.6x10(8), a small mode volume, and

  6. HCMT interaction of whispering gallery modes in circuits of integrated optical microring or -disk resonators

    NARCIS (Netherlands)

    Franchimon, Ellen F.; Hiremath, K.R.; Stoffer, Remco; Hammer, Manfred

    Whispering gallery modes (WGMs) supported by open circular dielectric cavities are embedded into a 2-D hybrid coupled mode theory (HCMT) framework. The model enables convenient studies of supermode formation in composite circuits (CROWS, photonic molecules), and of their excitation by straight

  7. Investigation of whispering gallery modes in microlasers by scanning near-field optical microscopy

    Science.gov (United States)

    Polubavkina, Yu S.; Kryzhanovskaya, N. V.; Nadtochiy, A. M.; Mintairov, A. M.; Lipovsky, A. A.; Scherbak, S. A.; Kulagina, M. M.; Maximov, M. V.; Zhukov, A. E.

    2017-11-01

    Near-field scanning optical microscopy (NSOM) with a spatial resolution below the light diffraction limit was used to study intensity distributions of the whispering gallery modes (WGMs) in quantum dot-based microdisk and microring lasers on GaAs with different outer diameters. Room temperature microphotoluminescence study (μPL) reveal lasing in microlasers of both geometries.

  8. Highly Stable On-Chip Embedded Organic Whispering Gallery Mode Lasers

    NARCIS (Netherlands)

    Lu, Shi-Yang; Fang, Hong-Hua; Feng, Jing; Xia, Hong; Zhang, Tie-Qiang; Chen, Qi-Dai; Sun, Hong-Bo; Fang, Honghua

    2014-01-01

    Chip-embedded organic resonator is fabricated with 2,5-Bis(4-biphenylyl)thiophene (BP1T) crystals encapsulated with polydimethylsiloxane (PDMS). Whispering gallery mode lasing is demonstrated in these on-chip embedded crystalline microresonators, without decline in the spectral properties, and

  9. Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern

    DEFF Research Database (Denmark)

    Schunk, Gerhard; Fuerst, Josef U.; Förtsch, Michael

    2014-01-01

    Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMR...

  10. Using Whispering-Gallery-Mode Resonators for Refractometry

    Science.gov (United States)

    Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry; Iltchenko, Vladimir; Maleki, Lute

    2010-01-01

    A method of determining the refractive and absorptive properties of optically transparent materials involves a combination of theoretical and experimental analysis of electromagnetic responses of whispering-gallery-mode (WGM) resonator disks made of those materials. The method was conceived especially for use in studying transparent photorefractive materials, for which purpose this method affords unprecedented levels of sensitivity and accuracy. The method is expected to be particularly useful for measuring temporally varying refractive and absorptive properties of photorefractive materials at infrared wavelengths. Still more particularly, the method is expected to be useful for measuring drifts in these properties that are so slow that, heretofore, the properties were assumed to be constant. The basic idea of the method is to attempt to infer values of the photorefractive properties of a material by seeking to match (1) theoretical predictions of the spectral responses (or selected features thereof) of a WGM of known dimensions made of the material with (2) the actual spectral responses (or selected features thereof). Spectral features that are useful for this purpose include resonance frequencies, free spectral ranges (differences between resonance frequencies of adjacently numbered modes), and resonance quality factors (Q values). The method has been demonstrated in several experiments, one of which was performed on a WGM resonator made from a disk of LiNbO3 doped with 5 percent of MgO. The free spectral range of the resonator was approximately equal to 3.42 GHz at wavelengths in the vicinity of 780 nm, the smallest full width at half maximum of a mode was approximately equal to 50 MHz, and the thickness of the resonator in the area of mode localization was 30 microns. In the experiment, laser power of 9 mW was coupled into the resonator with an efficiency of 75 percent, and the laser was scanned over a frequency band 9 GHz wide at a nominal wavelength of

  11. Interaction of whispering gallery modes in integrated optical micro-ring or -disk circuits: Hybrid CMT model

    NARCIS (Netherlands)

    Franchimon, Ellen F.; Hiremath, K.R.; Stoffer, Remco; Hammer, Manfred

    2013-01-01

    Whispering gallery modes supported by open circular dielectric cavities are embedded into a nonparametric two-dimensional frequency domain hybrid coupled mode theory framework. Regular aggregates of these cavities, including straight access channels, are investigated. The model enables convenient

  12. Whispering gallery mode resonators for frequency metrology applications

    Science.gov (United States)

    Baumgartel, Lukas

    This dissertation describes an investigation into the use of whispering gallery mode (WGM) resonators for applications towards frequency reference and metrology. Laser stabilization and the measurement of optical frequencies have enabled myriad technologies of both academic and commercial interest. A technology which seems to span both motivations is optical atomic clocks. These devices are virtually unimaginable without the ultra stable lasers plus frequency measurement and down-conversion afforded by Fabry Perot (FP) cavities and model-locked laser combs, respectively. However, WGM resonators can potentially perform both of these tasks while having the distinct advantages of compactness and simplicity. This work represents progress towards understanding and mitigating the performance limitations of WGM cavities for such applications. A system for laser frequency stabilization to a the cavity via the Pound-Drever-Hall (PDH) method is described. While the laser lock itself is found to perform at the level of several parts in 1015, a variety of fundamental and technical mechanisms destabilize the WGM frequency itself. Owing to the relatively large thermal expansion coefficients in optical crystals, environmental temperature drifts set the stability limit at time scales greater than the thermal relaxation time of the crystal. Uncompensated, these drifts pull WGM frequencies about 3 orders of magnitude more than they would in an FP cavity. Thus, two temperature compensation schemes are developed. An active scheme measures and stabilizes the mode volume temperature to the level of several nK, reducing the effective temperature coefficient of the resonator to 1.7x10-7 K-1; simulations suggest that the value could eventually be as low as 3.5x10-8 K-1, on par with the aforementioned FP cavities. A second, passive scheme is also described, which employs a heterogeneous resonator structure that capitalizes on the thermo-mechanical properties of one material and the optical

  13. Towards next-generation label-free biosensors: recent advances in whispering gallery mode sensors.

    Science.gov (United States)

    Kim, Eugene; Baaske, Martin D; Vollmer, Frank

    2017-03-29

    Whispering gallery mode biosensors have been widely exploited over the past decade to study molecular interactions by virtue of their high sensitivity and applicability in real-time kinetic analysis without the requirement to label. There have been immense research efforts made for advancing the instrumentation as well as the design of detection assays, with the common goal of progressing towards real-world sensing applications. We therefore review a set of recent developments made in this field and discuss the requirements that whispering gallery mode label-free sensors need to fulfill for making a real world impact outside of the laboratory. These requirements are directly related to the challenges that these sensors face, and the methods proposed to overcome them are discussed. Moving forward, we provide the future prospects and the potential impact of this technology.

  14. Magnetic-field tuning of whispering gallery mode lasing from ferromagnetic nematic liquid crystal microdroplets.

    Science.gov (United States)

    Mur, Maruša; Sofi, Junaid Ahmad; Kvasić, Ivan; Mertelj, Alenka; Lisjak, Darja; Niranjan, Vidur; Muševič, Igor; Dhara, Surajit

    2017-01-23

    We report magnetic field tuning of the structure and Whispering Gallery Mode lasing from ferromagnetic nematic liquid crystal micro-droplets. Microlasers were prepared by dispersing a nematic liquid crystal, containing magnetic nanoparticles and fluorescent dye, in a glycerol-lecithin matrix. The droplets exhibit radial director structure, which shows elastic distortion at a very low external magnetic field. The fluorescent dye doped ferromagnetic nematic droplets show Whispering Gallery Mode lasing, which is tunable by the external magnetic field. The tuning of the WGM lasing modes is linear in magnetic field with a wavelength-shift of the order of 1 nm/100 mT. Depending on the lasing geometry, the WGMs are red- or blue-shifted.

  15. Scattering of e Polarized Whispering-Gallery mode from Concave Boundary

    Directory of Open Access Journals (Sweden)

    Alexander P. Anyutin

    2012-03-01

    Full Text Available In this work we present numerical results for the 2D problem of scattering E polarised whispering-gallery mode from concave convex perfectly conducting boundary. The results were obtained by applying the developed method of currants integral equations (CIE [6,7] for high frequency domain when the size of the scatterer match is greater than the wave length. We have applied the described procedure in order to find numerical solutions of scattering whispering-gallery mode by concave finite convex boundary as a part of a circular cylinder or part of parabolic cylinder. As incident wave we have considered cylindrical waves from line source and Gauss beam [6] with different effective width. It is shown that we have a complicated process of focusing and oscillating of the beam’s reflected field, both cylindrical and Gauss beam incident fields. The distortions of reflected field depend on shape of the boundary and parameters of the incident fields.

  16. Low threshold Rhodamine-doped whispering gallery mode microlasers fabricated by direct laser writing.

    Science.gov (United States)

    Tomazio, Nathália B; Boni, Leonardo De; Mendonca, Cleber R

    2017-08-17

    The combination of the outstanding properties of whispering gallery modes with both the flexibility and ease of processing of polymers is particularly attractive for photonics applications. However, the versatile fabrication of polymeric nano/microdevices with the desired photonic performance has proven challenging. Here, we report on lasing in Rhodamine B doped whispering gallery mode microcavities fabricated by direct laser writing via two-photon polymerization. Threshold pump energies as low as 12 nJ were achieved for free-space pulsed excitation at 532 nm. To the best of our knowledge, this is the lowest laser threshold attained for microcavities fabricated in a single step of femtosecond laser writing, a remarkable feat that stands out from other fabrication methods.

  17. Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern.

    Science.gov (United States)

    Schunk, Gerhard; Fürst, Josef U; Förtsch, Michael; Strekalov, Dmitry V; Vogl, Ulrich; Sedlmeir, Florian; Schwefel, Harald G L; Leuchs, Gerd; Marquardt, Christoph

    2014-12-15

    Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs. The radial mode numbers q and the angular mode numbers p = ℓ-m are identified and labeled via far-field imaging. The polar mode numbers ℓ are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination of the geometry and the refractive index at different temperatures of the WGMR. For future applications in classical and quantum optics, this mode analysis enables one to control the narrow-band phase-matching conditions in nonlinear processes such as second-harmonic generation or parametric down-conversion.

  18. White-Light Whispering Gallery Mode Optical Resonator System and Method

    Science.gov (United States)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy A. (Inventor); Maleki, Lute (Inventor)

    2009-01-01

    An optical resonator system and method that includes a whispering-gallery mode (WGM) optical resonator that is capable of resonating across a broad, continuous swath of frequencies is provided. The optical resonator of the system is shaped to support at least one whispering gallery mode and includes a top surface, a bottom surface, a side wall, and a first curved transition region extending between the side wall and the top surface. The system further includes a coupler having a coupling surface which is arranged to face the transition region of the optical resonator and in the vicinity thereof such that an evanescent field emitted from the coupler is capable of being coupled into the optical resonator through the first curved transition region

  19. Coupled-mode induced transparency in a bottle whispering-gallery-mode resonator.

    Science.gov (United States)

    Wang, Yue; Zhang, Kun; Zhou, Song; Wu, Yi-Hui; Chi, Ming-Bo; Hao, Peng

    2016-04-15

    Whispering-gallery-mode (WGM) optical resonators are ideal systems for achieving electromagnetically induced transparency-like phenomenon. Here, we experimentally demonstrate that one or more transparent windows can be achieved with coupled-mode induced transparency (CMIT) in a single bottle WGM resonator due to the bottle's dense mode spectra and tunable resonant frequencies. This device offers an approach for multi-channel all-optical switching devices and sensitivity-enhanced WGM-based sensors.

  20. Efficient frequency generation in phoXonic cavities based on hollow whispering gallery mode resonators.

    Science.gov (United States)

    Farnesi, Daniele; Righini, Giancarlo; Nunzi Conti, Gualtiero; Soria, Silvia

    2017-03-07

    We report on nonlinear optical effects on phoxonic cavities based on hollow whispering gallery mode resonators pumped with a continuous wave laser. We observed stimulated scattering effects such as Brillouin and Raman, Kerr effects such as degenerated and non-degenerated four wave mixing, and dispersive wave generation. These effects happened concomitantly. Hollow resonators give rise to a very rich nonlinear scenario due to the coexistence of several family modes.

  1. In situ tuning of whispering gallery modes of levitated silica microspheres

    Science.gov (United States)

    Minowa, Yosuke; Toyota, Yusuke; Ashida, Masaaki

    2017-06-01

    We demonstrated the tuning of whispering gallery modes (WGMs) of a silica microsphere during optical levitation through the annealing process. We determined the annealing temperature from the power balance between the CO2 laser light heating and several cooling processes. Cooling caused by heat conduction through the surrounding air molecules is the dominant process. We achieved a blue shift of the WGMs as large as 1 \\%, which was observed in the white-light scattering spectrum from the levitated microsphere.

  2. Light absorption enhancement in thin-film solar cells using whispering gallery modes in dielectric nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Grandidier, Jonathan; Callahan, Dennis M.; Munday, Jeremy N.; Atwater, Harry A. [Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2011-03-11

    Freely propagating sunlight can be diffractively coupled and transformed into several guided whispering gallery modes within an array of wavelength scale dielectric spheres. Incident optical power is then transferred to the thin-film cell by leaky mode coupling into a thin solar cell absorber layer and significantly enhances its efficiency by increasing the fraction of incident light absorbed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Chasing the thermodynamical noise limit in whispering-gallery-mode resonators for ultrastable laser frequency stabilization.

    Science.gov (United States)

    Lim, Jinkang; Savchenkov, Anatoliy A; Dale, Elijah; Liang, Wei; Eliyahu, Danny; Ilchenko, Vladimir; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2017-03-31

    Ultrastable high-spectral-purity lasers have served as the cornerstone behind optical atomic clocks, quantum measurements, precision optical microwave generation, high-resolution optical spectroscopy, and sensing. Hertz-level lasers stabilized to high-finesse Fabry-Pérot cavities are typically used for these studies, which are large and fragile and remain laboratory instruments. There is a clear demand for rugged miniaturized lasers with stabilities comparable to those of bulk lasers. Over the past decade, ultrahigh-Q optical whispering-gallery-mode resonators have served as a platform for low-noise microlasers but have not yet reached the stabilities defined by their fundamental noise. Here, we show the noise characteristics of whispering-gallery-mode resonators and demonstrate a resonator-stabilized laser at this limit by compensating the intrinsic thermal expansion, allowing a sub-25 Hz linewidth and a 32 Hz Allan deviation. We also reveal the environmental sensitivities of the resonator at the thermodynamical noise limit and long-term frequency drifts governed by random-walk-noise statistics.High-quality optical resonators have the potential to provide a miniaturized frequency reference for metrology and sensing but they often lack stability. Here, Lim et al. experimentally characterize the stability of whispering-gallery resonators at their fundamental noise limits.

  4. Giant Rabi Splitting of Whispering Gallery Polaritons in GaN/InGaN Core-Shell Wire.

    Science.gov (United States)

    Gong, Su-Hyun; Ko, Suk-Min; Jang, Min-Ho; Cho, Yong-Hoon

    2015-07-08

    The hybrid nature of exciton polaritons opens up possibilities for developing a new concept nonlinear photonic device (e.g., polariton condensation, switching, and transistor) with great potential for controllability. Here, we proposed a novel type of polariton system resulting from strong coupling between a two-dimensional exciton and whispering gallery mode photon using a core-shell GaN/InGaN hexagonal wire. High quality, nonpolar InGaN multiple-quantum wells (MQWs) were conformally formed on a GaN core nanowire, which was spatially well matched with whispering gallery modes inside the wire. Both high longitudinal-transverse splitting of nonpolar MQWs and high spatial overlap with whispering gallery modes lead to unprecedented large Rabi splitting energy of ∼180 meV. This structure provides a robust polariton effect with a small footprint; thus, it could be utilized for a wide range of interesting applications.

  5. Integration of microsphere resonators with bioassay fluidics for whispering gallery mode imaging.

    Science.gov (United States)

    Kim, Daniel C; Armendariz, Kevin P; Dunn, Robert C

    2013-06-07

    Whispering gallery mode resonators are small, radially symmetric dielectrics that trap light through continuous total internal reflection. The resonant condition at which light is efficiently confined within the structure is linked with refractive index, which has led to the development of sensitive label-free sensing schemes based on whispering gallery mode resonators. One resonator design uses inexpensive high index glass microspheres that offer intrinsically superior optical characteristics, but have proven difficult to multiplex and integrate with the fluidics for sample delivery and fluid exchange necessary for assay development. Recently, we introduced a fluorescence imaging approach that enables large scale multiplexing with microsphere resonators, thus removing one obstacle for assay development. Here we report an approach for microsphere immobilization that overcomes limitations arising from their integration with fluidic delivery. The approach is an adaptation of a calcium-assisted glass bonding method originally developed for microfluidic glass chip fabrication. Microspheres bonded to glass using this technique are shown to be stable with respect to fluid flow and show no detectable loss in optical performance. Measured Q-factors, for example, remain unchanged following sphere bonding to the substrate. The stability of the immobilized resonators is further demonstrated by transferring lipid films onto the immobilized spheres using the Langmuir-Blodgett technique. Bilayers of DOPC doped with GM1 were transferred onto immobilized resonators to detect the binding of cholera toxin to GM1. Binding curves generated from shifts in the whispering gallery mode resonance result in a measured Kd of 1.5 × 10(-11) with a limit of detection of 3.3 pM. These results are discussed in terms of future assay development using microsphere resonators.

  6. Whispering gallery mode lasing in high quality GaAs/AlAs pillar microcavities

    Science.gov (United States)

    Jaffrennou, P.; Claudon, J.; Bazin, M.; Malik, N. S.; Reitzenstein, S.; Worschech, L.; Kamp, M.; Forchel, A.; Gérard, J.-M.

    2010-02-01

    We report whispering gallery mode (WGM) lasing from high quality GaAs/AlAs micropillars with embedded InAs quantum dots, under continuous optical pumping. For temperatures ranging from 5 to 100 K, simultaneous lasing from TE1,1,m WGMs is observed for pillar diameters in the 3-4 μm range. Spectral linewidths and energy shifts of the lasing modes are analyzed as a function of the pump power. Thanks to the efficient heat sinking provided by the micropillar geometry, a clear line narrowing is observed above threshold. Moreover, the lasing mode energy remains stable for pump power as large as six times the lasing threshold.

  7. Whispering Gallery Mode Based Optical Fiber Sensor for Measuring Concentration of Salt Solution

    Directory of Open Access Journals (Sweden)

    Chia-Chin Chiang

    2013-01-01

    Full Text Available An optical fiber solution-concentration sensor based on whispering gallery mode (WGM is proposed in this paper. The WGM solution-concentration sensors were used to measure salt solutions, in which the concentrations ranged from 1% to 25% and the wavelength drifted from the left to the right. The experimental results showed an average sensitivity of approximately 0.372 nm/% and an R2 linearity of 0.8835. The proposed WGM sensors are of low cost, feasible for mass production, and durable for solution-concentration sensing.

  8. Wavelength shift in a whispering gallery microdisk due to bacterial sensing: A theoretical approach

    Directory of Open Access Journals (Sweden)

    Hala Ghali

    2017-04-01

    Full Text Available Whispering gallery mode microcavities have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Binding of a biomolecule to the surface of a microresonator will increase its path length, leading to a shift in the resonance frequency according to the reactive sensing principle. In this paper, we develop a theoretical expression that will link the reactive shift to the bacteria and microdisk parameters and help quantify the number of bacteria that bind to the surface of a 200μm-diameter silica microdisk.

  9. Generalized full-vector multi-mode matching analysis of whispering gallery microcavities.

    Science.gov (United States)

    Du, Xuan; Vincent, Serge; Faucher, Mathieu; Picard, Marie-Josée; Lu, Tao

    2014-06-02

    We outline a full-vectorial three-dimensional multi-mode matching technique in a cylindrical coordinate system that addresses the mutual coupling among multiple modes co-propagating in a perturbed whispering gallery mode microcavity. In addition to its superior accuracy in respect to our previously implemented single-mode matching technique, this current technique is suitable for modelling waveguide-to-cavity coupling where the influence of multi-mode coupling is non-negligible. Using this methodology, a robust scheme for hybrid integration of a microcavity onto a silicon-on-insulator platform is proposed.

  10. Whispering gallery mode laser based on cholesteric liquid crystal microdroplets as temperature sensor

    Science.gov (United States)

    Zhao, Liyuan; Wang, Yan; Yuan, Yonggui; Liu, Yongjun; Liu, Shuangqiang; Sun, Weimin; Yang, Jun; Li, Hanyang

    2017-11-01

    We developed a tunable whispering gallery mode (WGM) microlaser based on dye-doped cholesteric liquid crystal (CLC) microdroplets with controllable size in an aqueous environment. An individual dye-doped CLC microdroplet confined at the tip of a microcapillary was optically pumped via a tapered optical fiber tip positioned within its vicinity. Numerical simulations and various spectral characteristics verify the WGM resonance of the lasing in microdroplets. Thermal tuning of the lasing modes is realized due to the thermo-optic effect of CLC. The proposed CLC microdroplet-based WGM resonator was applied as a temperature sensor and exhibited maximum temperature sensitivity up to 0.96 nm/°C.

  11. Low-Threshold Optical Parametric Oscillations in a Whispering Gallery Mode Resonator

    DEFF Research Database (Denmark)

    Fürst, J. U.; Strekalov, D. V.; Elser, D.

    2010-01-01

    In whispering gallery mode (WGM) resonator light is guided by continuous total internal reflection along a curved surface. Fabricating such resonators from an optically nonlinear material one takes advantage of their exceptionally high quality factors and small mode volumes to achieve extremely...... such an optical parametric oscillator (OPO) based on naturally phase-matched PDC in lithium niobate. We demonstrated a single-mode, strongly nondegenerate OPO with a threshold of 6.7  μW and linewidth under 10 MHz. This work demonstrates the remarkable capabilities of WGM-based OPOs....

  12. Entanglement of separate nitrogen-vacancy centers coupled to a whispering-gallery mode cavity

    Energy Technology Data Exchange (ETDEWEB)

    Yang Wanli; Xu Zhenyu; Feng Mang [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Du Jiangfeng, E-mail: mangfeng@wipm.ac.c, E-mail: djf@ustc.edu.c [Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

    2010-11-15

    We present a quantum electrodynamical model involving nitrogen-vacancy centers coupled to a whispering-gallery mode cavity. We consider two schemes to create the W state and Bell state, respectively. One scheme makes use of Raman transition with the cavity field virtually excited, and the other enables Bell state preparation and quantum information transfer by virtue of dark state evolution and adiabatic passage, which is tolerant to ambient noise and experimental parameter fluctuations. We justify our schemes by considering their experimental feasibility and challenge, using the currently available technology.

  13. THz Pyro-Optical Detector Based on LiNbO₃ Whispering Gallery Mode Microdisc Resonator.

    Science.gov (United States)

    Cosci, Alessandro; Cerminara, Matteo; Conti, Gualtiero Nunzi; Soria, Silvia; Righini, Giancarlo C; Pelli, Stefano

    2017-01-28

    This study analyzes the capabilities of a LiNbO₃ whispering gallery mode microdisc resonator as a potential bolometer detector in the THz range. The resonator is theoretically characterized in the stationary regime by its thermo-optic and thermal coefficients. Considering a Q-factor of 10⁷, a minimum detectable power of 20 μW was evaluated, three orders of magnitude above its noise equivalent power. This value opens up the feasibility of exploiting LiNbO₃ disc resonators as sensitive room-temperature detectors in the THz range.

  14. Solid-state Raman quantum memory in whispering gallery mode resonators: signal-to-noise ratio

    Science.gov (United States)

    Berezhnoi, Alexander; Kalachev, Alexey

    2017-10-01

    The possibility of implementation of optical quantum memory via off-resonant Raman absorption and emission of single-photon pulses in rare-earth-ion-doped crystals is theoretically analysed taking into account signal-to-noise ratio at the output of the memory device. The crystal 143Nd3+:Y7LiF4 is considered as an example. It is shown that the signal-to-noise ratio can exceed unity for single-photon input pulses provided that storage and retrieval of them is performed in the doped crystals forming a microcavity such as whispering gallery mode resonator.

  15. Rapid 3D µ-printing of polymer optical whispering-gallery mode resonators.

    Science.gov (United States)

    Wu, Jushuai; Guo, Xin; Zhang, A Ping; Tam, Hwa-Yaw

    2015-11-16

    A novel microfabrication method for rapid printing of polymer optical whispering-gallery mode (WGM) resonators is presented. A 3D micro-printing technology based on high-speed optical spatial modulator (SLM) and high-power UV light source is developed to fabricate suspended-disk WGM resonator array using SU-8 photoresist. The optical spectral responses of the fabricated polymer WGM resonators were measured with a biconically tapered optical fiber. Experimental results reveal that the demonstrated method is very flexible and time-saving for rapid fabrication of complex polymer WGM resonators.

  16. Optical Sensors Based on Whispering Gallery Modes in Fluorescent Microbeads: Size Dependence and Influence of Substrate

    Directory of Open Access Journals (Sweden)

    Alexandre Francois

    2009-08-01

    Full Text Available Whispering gallery modes in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing changes in the refractive index of the beads’ environment by exposing them to water/glycerol mixtures of varying composition. The mode positions are analyzed by simultaneous fitting for mode number, bead radius, and environmental index. Down to a diameter of 8 μm, the sensor response follows the index of the bulk solution very well. For smaller bead sizes, some deviations occur, in particular for fluid indices not too different from that of water, which might be attributed to the presence of the substrate.

  17. Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

    Science.gov (United States)

    Neilson, Jeffrey M

    2015-02-24

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  18. Optical Sensors Based on Whispering Gallery Modes in Fluorescent Microbeads: Response to Specific Interactions

    Science.gov (United States)

    Himmelhaus, Michael; Krishnamoorthy, Sivashankar; Francois, Alexandre

    2010-01-01

    Whispering gallery modes (WGMs) in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing the formation of biochemical adsorption layers on their outer surface with the well-established biotin-streptavidin specific binding as the model system. Three different methods for analysis of the observed shifts in the WGM wavelength positions are applied and used to quantify the adsorbed mass densities, which are then compared with the results of a comparative surface plasmon resonance (SPR) study. PMID:22219711

  19. Polarized photoluminescence study of whispering gallery mode polaritons in ZnO microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Liaoxin; Chen, Zhanghai; Ren, Qijun; Zhou, Weihang; Bai, Lihui; Shen, Xuechu [Surface Physics Laboratory, Department of Physics, Fudan University, Shanghai (China); Yu, Ke; Zhu, Z.Q. [Department of Electronic Engineering, East China Normal University, Shanghai (China)

    2009-01-15

    Polariton effect and its polarization dependence were studied in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning the excitation along the tapered arm of ZnO tetrapod with different polarizations, the photo-exciton coupling strength were continuingly tuned and thus the resonant interaction between the WG optical modes and the excitons with different dipole orientation are clearly resolved. The experimental observations were well described by the plane wave model with excitonic polariton dispersions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

    Science.gov (United States)

    Stallard, Barry W.; Makowski, Michael A.; Byers, Jack A.

    1992-01-01

    An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k.sub..phi. component of the propagation vector of the gyrotron output beam. The second mirror has a twist reflector to linearly polarize the beam. The third mirror has a constant phase surface so the converter output is in phase.

  1. Solid-state Raman quantum memory in whispering gallery mode resonators: signal-to-noise ratio

    Directory of Open Access Journals (Sweden)

    Berezhnoi Alexander

    2017-01-01

    Full Text Available The possibility of implementation of optical quantum memory via off-resonant Raman absorption and emission of single-photon pulses in rare-earth-ion-doped crystals is theoretically analysed taking into account signal-to-noise ratio at the output of the memory device. The crystal 143Nd3+:Y7LiF4 is considered as an example. It is shown that the signal-to-noise ratio can exceed unity for single-photon input pulses provided that storage and retrieval of them is performed in the doped crystals forming a microcavity such as whispering gallery mode resonator.

  2. Coupled-mode-induced transparency in aerostatically tuned microbubble whispering-gallery resonators.

    Science.gov (United States)

    Yang, Yong; Saurabh, Sunny; Ward, Jonathan; Chormaic, Síle Nic

    2015-04-15

    Coupled-mode-induced transparency is realized in a single microbubble whispering-gallery mode resonator. Using aerostatic tuning, we find that the pressure-induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference, and this is confirmed by experiments. A transparency spectrum is obtained when a first-order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  3. Electrodynamical Light Trapping Using Whispering-Gallery Resonances in Hyperbolic Cavities

    Directory of Open Access Journals (Sweden)

    Chihhui Wu

    2014-04-01

    Full Text Available We theoretically study spherical cavities composed of hyperbolic metamaterials with indefinite permittivity tensors. Such cavities are capable of electrodynamically confining fields with deep subwavelength cavity sizes. The supported resonant modes are analogous to the whispering-gallery modes found in dielectric microcavities with much larger physical sizes. Because of the nature of electrodynamical confinement, these hyperbolic metamaterial cavities exhibit quality factors higher than predicted in the electrostatic limit. In addition, confining electromagnetic fields into the small cavities results in an extremely high photonic local density of states.

  4. Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators

    CERN Document Server

    Yang, Yong; Ward, Jonathan; Chormaic, Síle Nic

    2015-01-01

    Coupled-mode induced transparency is realized in a single microbubble whispering gallery mode resonator. Using aerostatic tuning, we find that the pressure induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference and this is confirmed by experiments. A transparency spectrum is obtained when a first order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  5. Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K

    2015-01-01

    We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  6. Whispering gallery mode photoemission from self-assembled poly-para-phenylenevinylene microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Kushida, Soh; Yamamoto, Yohei [Division of Materials Science and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Braam, Daniel; Lorke, Axel [Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstraße 1, Duisburg, D-47048 (Germany)

    2015-12-31

    Poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMOPPV) self-assembles to form well-defined spheres with several micrometers in diameter upon addition of a methanol vapor into a chloroform solution of MDMOPPV. The single sphere of MDMOPPV with 5.7 µm diameter exhibits whispering gallery mode (WGM) photoemission upon excitation with focused laser beam. The periodic emission lines are characterized by transverse electric and magnetic WGMs, and Q-factor reaches ∼345 at the highest.

  7. On-Chip Glass Microspherical Shell Whispering Gallery Mode Resonators.

    Science.gov (United States)

    Zhang, Chenchen; Cocking, Alexander; Freeman, Eugene; Liu, Zhiwen; Tadigadapa, Srinivas

    2017-11-02

    Arrays of on-chip spherical glass shells of hundreds of micrometers in diameter with ultra-smooth surfaces and sub-micrometer wall thicknesses have been fabricated and have been shown to sustain optical resonance modes with high Q-factors of greater than 50 million. The resonators exhibit temperature sensitivity of -1.8 GHz K-1 and can be configured as ultra-high sensitivity thermal sensors for a broad range of applications. By virtue of the geometry's strong light-matter interaction, the inner surface provides an excellent on-chip sensing platform that truly opens up the possibility for reproducible, chip scale, ultra-high sensitivity microfluidic sensor arrays. As a proof of concept we demonstrate the sensitivity of the resonance frequency as water is filled inside the microspherical shell and is allowed to evaporate. By COMSOL modeling, the dependence of this interaction on glass shell thickness is elucidated and the experimentally measured sensitivities for two different shell thicknesses are explained.

  8. Pseudo-type-II tuning behavior and mode identification in whispering gallery optical parametric oscillators.

    Science.gov (United States)

    Meisenheimer, Sarah-Katharina; Fürst, Josef Urban; Schiller, Annelie; Holderied, Florian; Buse, Karsten; Breunig, Ingo

    2016-06-27

    Wavelength tuning of conventional mirror-based optical parametric oscillators (OPOs) exhibits parabolically-shaped tuning curves (type-0 and type-I phase matching) or tuning branches that cross each other with a finite slope (type-II phase matching). We predict and experimentally prove that whispering gallery OPOs based on type-0 phase matching show both tuning behaviors, depending on whether the mode numbers of the generated waves coincide or differ. We investigate the wavelength tuning of optical parametric oscillation in a millimeter-sized radially-poled lithium niobate disk pumped at 1 μm wavelength generating signal and idler waves between 1.7 and 2.6 μm wavelength. Our experimental findings excellently coincide with the theoretical predictions. The investigated whispering gallery optical parametric oscillator combines the employment of the highest nonlinear-optical coefficient of the material with a controlled type-II-like wavelength tuning and with the possibility of self-phase locking.

  9. Unified theory of whispering gallery multilayer microspheres with single dipole or active layer sources.

    Science.gov (United States)

    Hall, Jonathan M M; Reynolds, Tess; Henderson, Matthew R; Riesen, Nicolas; Monro, Tanya M; Afshar, Shahraam

    2017-03-20

    The development of a fast and reliable whispering gallery mode (WGM) simulator capable of generating spectra that are comparable with experiment is an important step forward for designing microresonators. We present a new model for generating WGM spectra for multilayer microspheres, which allows for an arbitrary number of concentric dielectric layers, and any number of embedded dipole sources or uniform distributions of dipole sources to be modeled. The mode excitation methods model embedded nanoparticles, or fluorescent dye coatings, from which normalized power spectra with accurate representation of the mode coupling efficiencies can be derived. In each case, the emitted power is expressed conveniently as a function of wavelength, with minimal computational load. The model makes use of the transfer-matrix approach, incorporating improvements to its stability, resulting in a reliable, general set of formulae for calculating whispering gallery mode spectra. In the specific cases of the dielectric microsphere and the single-layer coated microsphere, our model simplifies to confirmed formulae in the literature.

  10. Tunable waveguide and cavity in a phononic crystal plate by controlling whispering-gallery modes in hollow pillars

    DEFF Research Database (Denmark)

    Jin, Yabin; Fernez, Nicolas; Pennec, Yan

    2016-01-01

    We investigate the properties of a phononic crystal plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic crystal...

  11. Whispering-gallery-mode dye lasers in blue, green, and orange regions using dye-doped, solid, small spheres

    OpenAIRE

    Taniguchi, Hiroshi; Fujiwara, Tamiya; Yamada, Hiroshi; Tanosaki, Shinji; Baba, Mamoru

    1993-01-01

    A whispering-gallery-mode (WGM) dye laser in blue, green, and orange regions is reported using dye-doped, solid, small spheres. A WGM dye laser is pumped by a transversely excited atmospheric UV N2 laser. Some features of the WGM dye laser are demonstrated.

  12. Under-Coupling Whispering Gallery Mode Resonator Applied to Resonant Micro-Optic Gyroscope

    Directory of Open Access Journals (Sweden)

    Kun Qian

    2017-01-01

    Full Text Available As an important sensing element, the whispering gallery mode resonator (WGMR parameters seriously affect the resonant micro-optic gyroscope (RMOG performance. This work proposes an under-coupling resonator to improve the resonator’s Q value and to optimize the coupling coefficient to maximize the RMOG’s sensitivity. GeO2-doped silica waveguide-type resonators with different coupling coefficients were simulated, designed, fabricated and tested. An under-coupling ring resonator with a quality factor of 10 million is reported. The RMOG system was built based on this resonator and the scale factor was tested on a uniaxial high-precision rotating platform. Experimental results show that this resonator could improve the RMOG sensitivity by five times.

  13. Under-Coupling Whispering Gallery Mode Resonator Applied to Resonant Micro-Optic Gyroscope.

    Science.gov (United States)

    Qian, Kun; Tang, Jun; Guo, Hao; Liu, Wenyao; Liu, Jun; Xue, Chenyang; Zheng, Yongqiu; Zhang, Chengfei

    2017-01-06

    As an important sensing element, the whispering gallery mode resonator (WGMR) parameters seriously affect the resonant micro-optic gyroscope (RMOG) performance. This work proposes an under-coupling resonator to improve the resonator's Q value and to optimize the coupling coefficient to maximize the RMOG's sensitivity. GeO₂-doped silica waveguide-type resonators with different coupling coefficients were simulated, designed, fabricated and tested. An under-coupling ring resonator with a quality factor of 10 million is reported. The RMOG system was built based on this resonator and the scale factor was tested on a uniaxial high-precision rotating platform. Experimental results show that this resonator could improve the RMOG sensitivity by five times.

  14. Whispering gallery mode lasing in optically isolated III-nitride nanorings.

    Science.gov (United States)

    Li, K H; Cheung, Y F; Choi, H W

    2015-06-01

    III-nitride nanorings fabricated from a combination of hybrid-nanosphere-lithography and laser lift-off processes is demonstrated. Being formed on an interfacial metallic layer optically coupling between the optical ring and its substrate is eliminated, maximizing optical confinement of whispering gallery resonant mode within the ring cavity. The tapered cross-sectional profile also promotes coupling of emitted light into resonant modes. Optically pumped lasing with a dominant peak at 421.5 nm is observed at room temperature, with threshold energy density of ∼6.5  mJ/cm2. Etch-induced sidewall roughness causes scattering of light at the interface to diminish confinement, and is also responsible for the mode-splitting effect according to finite-difference time-domain simulations.

  15. Hybrid plasmonic-photonic whispering gallery mode resonators for sensing: a critical review.

    Science.gov (United States)

    Bozzola, Angelo; Perotto, Sara; De Angelis, Francesco

    2017-03-13

    In this review we present the state of the art and the most recent advances in the field of optical sensing with hybrid plasmonic-photonic whispering gallery mode (WGM) resonators. After a brief introduction on the basic physics behind photonic WGM resonators and localized surface plasmon (LSP) nanostructures, we analyze the different types of optical sensors specifically designed for bulk refractive index sensing, molecular binding and single object detection. We point out the physical and technological key points of the different approaches proposed in the literature, and we systematically compare hybrid sensors and purely photonic WGM sensors. This comparative analysis points out the real advantages brought by LSP nanostructures, and it identifies the most promising hybrid architectures.

  16. Computational model and simulation for the whispering gallery modes inside micro-optical cavity

    Science.gov (United States)

    Ali, Amir R.; Erian, Abanoub M.; Shokry, Kirelloss

    2017-05-01

    A computational model for the whispering gallery modes inside a microsphere resonator is presented. In the archetypical microsphere resonator sensor, a tunable laser light beam is injected into an optical fiber and coupled with the resonator's cavity. The resonant optical coupling is achieved by bringing the fiber in the vicinity of the cavity's evanescent field. The transmission spectrum is then observed to detect the WGM shifts. In this paper, two-dimensional models of a single laser source put near the equator of a microsphere are simulated using COMSOL Multi-physics 5.1 electromagnetic waves, beam envelopes library. Afterwards, a three-dimensional model of two laser sources put near the horizontal and vertical equators of a microsphere is computed. The transmission spectrum of both simulations was taken and cross correlation was performed on them. Results show a big similarity between both simulations and could bring a breakthrough in the area of optical sensors.

  17. Whispering-gallery mode lasing from optically free-standing InGaN microdisks.

    Science.gov (United States)

    Zhang, Xuhui; Cheung, Yuk Fai; Zhang, Yiyun; Choi, H W

    2014-10-01

    Optically pumped multi-mode whispering-gallery mode (WGM) lasing has been observed in optically free-standing InGaN/GaN quantum well microdisks at room temperature. The ∼6.6  μm optically isolated microdisks are patterned by microsphere lithography on GaN thin-films prepared by laser lift-off of the sapphire substrate, enabling superior optical confinement. The modes are determined to be of second order according to simulations. The lasing threshold is found to be ∼9.06  mJ/cm2, with a quality factor Q of ∼770 evaluated from the dominant mode at λ=430.2  nm, and a free space range (FSR) of 3.17 to 2.16 nm, which is mode-dependent.

  18. III-nitride tunable cup-cavities supporting quasi whispering gallery modes from ultraviolet to infrared

    Science.gov (United States)

    Shubina, T. V.; Pozina, G.; Jmerik, V. N.; Davydov, V. Yu.; Hemmingsson, C.; Andrianov, A. V.; Kazanov, D. R.; Ivanov, S. V.

    2015-01-01

    Rapidly developing nanophotonics needs microresonators for different spectral ranges, formed by chip-compatible technologies. In addition, the tunable ones are much in demand. Here, we present site-controlled III-nitride monocrystal cup-cavities grown by molecular beam epitaxy. The cup-cavities can operate from ultraviolet to near-infrared, supporting quasi whispering gallery modes up to room temperature. Besides, their energies are identical in large ’ripened’ crystals. In these cavities, the refractive index variation near an absorption edge causes the remarkable effect of mode switching, which is accompanied by the spatial redistribution of electric field intensity with concentration of light into a subwavelength volume. Our results shed light on the mode behavior in semiconductor cavities and open the way for single-growth-run manufacturing the devices comprising an active region and a cavity with tunable mode frequencies. PMID:26656267

  19. Whispering-gallery-mode microlaser based on self-assembled organic single-crystalline hexagonal microdisks.

    Science.gov (United States)

    Wang, Xuedong; Liao, Qing; Kong, Qinghua; Zhang, Yi; Xu, Zhenzhen; Lu, Xiaomei; Fu, Hongbing

    2014-06-02

    Whispering-gallery-mode (WGM) resonators of semiconductor microdisks have been applied for achieving low-threshold and narrow-linewidth microlasers, but require sophisticated top-down processing technology. Organic single-crystalline hexagonal microdisks (HMDs) of p-distyrylbenzene (DSB) self-assembled from solution can function as WGM microresonators with a cavity quality factor (Q) of 210. Both multiple- and single-mode lasing had been achieved using DSB HMDs with an edge length of 4.3 and 1.2 μm, respectively. These organic microdisks fabricated by bottom-up self-assembly approach may offer potential applications as low-threshold microlaser sources for photonic circuit integration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Experimental demonstration of critical coupling of whispering gallery mode cavities on a Bloch surface wave platform.

    Science.gov (United States)

    Vosoughi Lahijani, B; Badri Ghavifekr, H; Dubey, R; Kim, M-S; Vartiainen, I; Roussey, M; Herzig, H P

    2017-12-15

    We experimentally demonstrate critical coupling of whispering gallery mode (WGM) disk resonators implemented on a Bloch surface wave platform using scanning near-field optical microscopy. The studied structure is a 60 nm thick TiO2 WGM disk cavity (radius of 100 μm) operating within the C-band telecommunication wavelength. An extinction ratio of 26 dB and a quality factor of 2200 are measured. Such a high extinction ratio verifies the critical coupling of the WGM resonator. This result paves the way to planar optical signal processing devices based on the proposed geometry, for which a critical coupling condition is a guarantee of optimum performance.

  1. Whispering gallery mode single nanoparticle detection and sizing: the validity of the dipole approximation.

    Science.gov (United States)

    Foreman, Matthew R; Keng, David; Treasurer, Eshan; Lopez, Jehovani R; Arnold, Stephen

    2017-03-01

    Interactions between whispering gallery modes (WGMs) and small nanoparticles are commonly modeled by treating the particle as a point dipole scatterer. This approach is assumed to be accurate as long as the nanoparticle radius, a, is small compared to the WGM wavelength λ. In this Letter, however, we show that the large field gradients associated with the evanescent decay of a WGM causes the dipole theory to significantly underestimate the interaction strength and, hence, the induced WGM resonance shift, even for particles as small as a∼λ/10. To mitigate this issue, we employ a renormalized Born approximation to more accurately determine nanoparticle-induced resonance shifts and, hence, enable improved particle sizing. The domain of validity of this approximation is investigated, and supporting experimental results are presented.

  2. Thermal sensing based on whispering gallery modes in tapered-fiber-coupled liquid crystal microdroplets

    Science.gov (United States)

    Wang, Yan; Li, Hanyang; Zhao, Liyuan; Liu, Yongjun; Liu, Shuangqiang; Yang, Jun

    2017-04-01

    We report the efficient coupling of optical whispering gallery modes (WGMs) in liquid crystal microdroplets suspended in immiscible aqueous environment. Individual nematic liquid crystal (NLC) microdroplet is confined at the tip of a microcapillary used to generate the microdroplets and coupled through a tapered optical fiber waveguide positioned in the vicinity of the microdroplets. Efficient coupling of WGMs is observed in the NLC microdroplets with a diameter of 50-150 μm. In addition, the wavelengths of the WGMs can be tuned by temperature, making such NLC microdroplets suitable for thermal sensors. A temperature sensitivity of 0.244 nm/°C is achieved in a 75-μm-diameter microdroplet. The estimated thermal resolution of the microdroplet sensor is 8.2 × 10-2 °C.

  3. Tuning Whispering Gallery Mode Lasing from Self-Assembled Polymer Droplets

    Science.gov (United States)

    Ta, Van Duong; Chen, Rui; Sun, Han Dong

    2013-01-01

    Optical microcavities are important for both fundamental studies of light-matter interaction and applications such as microlasers, optical switches and filters etc... Tunable microresonators, in which resonant modes can be manipulated, are especially fascinating. Here we demonstrate a unique approach to mechanically tuning microresonators formed by polymer droplets with varying sizes. The droplets are self-assembly inside an elastic medium. By incorporating different dye molecules into the droplets, optically pumped lasing with selective wavelengths in a range of about 100 nm are achieved. Lasing action is ascribed to whispering gallery modes, verified by rigorous characterizations. Single longitudinal mode lasing is obtained when the droplet diameter is reduced to about 14 μm. Tuning lasing modes are clearly demonstrated by mechanical deformation. Our finding provides an excellent platform for exploring flexible and tunable microlasers for plastic optoelectronic devices. PMID:23449157

  4. Phase-locking transition in Raman combs generated with whispering gallery mode resonators.

    Science.gov (United States)

    Lin, Guoping; Chembo, Yanne K

    2016-08-15

    We investigate the mechanisms leading to phase locking in Raman optical frequency combs generated with ultrahigh Q crystalline whispering gallery mode disk resonators. We show that several regimes can be triggered depending on the pumping conditions, such as single-frequency Raman lasing, multimode operation involving more than one family of cavity eigenmodes, and Kerr-assisted Raman frequency comb generation. The phase locking and coherence of the combs are experimentally monitored through the measurement of beat signal spectra. These phase-locked combs, which feature high coherence and wide spectral spans, are obtained with pump powers in the range of a few tens of mW. In particular, Raman frequency combs with multiple free-spectral range spacings are reported, and the measured beat signal in the microwave domain features a 3 dB linewidth smaller than 50 Hz, thereby indicating phase locking.

  5. One-dimensional finite-elements method for the analysis of whispering gallery microresonators.

    Science.gov (United States)

    Bagheri-Korani, Ebrahim; Mohammad-Taheri, Mahmoud; Shahabadi, Mahmoud

    2014-07-01

    By taking advantage of axial symmetry of the planar whispering gallery microresonators, the three-dimensional (3D) problem of the resonator is reduced to a two-dimensional (2D) one; thus, only the cross section of the resonator needs to be analyzed. Then, the proposed formulation, which works based on a combination of the finite-elements method (FEM) and Fourier expansion of the fields, can be applied to the 2D problem. First, the axial field variation is expressed in terms of a Fourier series. Then, a FEM method is applied to the radial field variation. This formulation yields an eigenvalue problem with sparse matrices and can be solved using a well-known numerical technique. This method takes into account both the radiation loss and the dielectric loss; hence, it works efficiently either for high number or low number modes. Efficiency of the method was investigated by comparison of the results with those of commercial software.

  6. The whispering gallery mode biosensor: label-free detection from virus to single protein

    Science.gov (United States)

    Holler, S.; Dantham, V. R.; Keng, D.; Kolchenko, V.; Arnold, S.; Mulroe, Brigid; Paspaley-Grbavac, M.

    2014-08-01

    The whispering gallery mode (WGM) biosensor is a micro-optical platform capable of sensitive label-free detection of biological particles. Described by the reactive sensing principle (RSP), this analytic formulation quantifies the response of the system to the adsorption of bioparticles. Guided by the RSP, the WGM biosensor enabling from detection of virus (e.g., Human Papillomavirus, HPV) to the ultimate goal of single protein detection. The latter was derived from insights into the RSP, which resulted in the development of a hybrid plasmonic WGM biosensor, which has recently demonstrated detection of individual protein cancer markers. Enhancements from bound gold nanoparticles provide the sensitivity to detect single protein molecules (66 kDa) with good signal-to-noise (S/N > 10), and project that detection of proteins as small as 5 kDa.

  7. Visualizing the condensation of graphene whispering gallery modes into Landau levels in real-space

    Science.gov (United States)

    Gutierrez, Christopher; Walkup, Daniel; Ghahari, Fereshte; Watanabe, Kenji; Taniguchi, Takashi; Zhitenev, Nikolai B.; Stroscio, Joseph A.

    Recent methods for the creation of circular p-n junctions in graphene have opened the door to investigating the effects of spatial confinement on Dirac fermions, such as the formation of whispering gallery modes (WGMs). These quasi-bound modes can be confined even further into highly-degenerate Landau levels by the application of a perpendicular magnetic field. Here we use scanning tunneling microscopy and spectroscopy (STM/STS) to investigate the effects of increasing magnetic field on the graphene WGMs in graphene/boron nitride heterostructures. Using detailed differential conductance (dI/dV) mapping we directly visualize the condensation of the distinct WGMs into degenerate Landau levels. We further show that residual disorder allows for the imaging of cyclotron orbits and circular edge modes.

  8. Origin of optical losses in gallium arsenide disk whispering gallery resonators

    CERN Document Server

    Parrain, David; Wang, Guillaume; Guha, Biswarup; Santos, Eduardo Gil; Lemaitre, Aristide; Senellart, Pascale; Leo, Giuseppe; Ducci, Sara; Favero, Ivan

    2015-01-01

    Whispering gallery modes in GaAs disk resonators reach half a million of optical quality factor. These high Qs remain still well below the ultimate design limit set by bending losses. Here we investigate the origin of residual optical dissipation in these devices. A Transmission Electron Microscope analysis is combined with an improved Volume Current Method to precisely quantify optical scattering losses by roughness and waviness of the structures, and gauge their importance relative to intrinsic material and radiation losses. The analysis also provides a qualitative description of the surface reconstruction layer, whose optical absorption is then revealed by comparing spectroscopy experiments in air and in different liquids. Other linear and nonlinear optical loss channels in the disks are evaluated likewise. Routes are given to further improve the performances of these miniature GaAs cavities.

  9. Barium fluoride whispering-gallery-mode disk-resonator with one billion quality-factor

    CERN Document Server

    Lin, Guoping; Henriet, Rémi; Jacquot, Maxime; Chembo, Yanne K

    2015-01-01

    We demonstrate a monolithic optical whispering gallery mode resonator fabricated with barium fluoride (BaF$_2$) with an ultra-high quality ($Q$) factor above $10^9$ at $1550$ nm, and measured with both the linewidth and cavity-ring-down methods. Vertical scanning optical profilometry shows that the root mean square surface roughness of $2$ nm is achieved for our mm-size disk. To the best of our knowledge, we show for the first time that one billion $Q$-factor is achievable by precision polishing in relatively soft crystals with mohs hardness of ~$3$. We show that complex thermo-optical dynamics can take place in these resonators. Beside usual applications in nonlinear optics and microwave photonics, high energy particle scintillation detection utilizing monolithic BaF$_2$ resonators potentially becomes feasible.

  10. Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Ward, Jonathan M; Chormaic, Síle Nic

    2016-01-01

    In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady state transmission spectrum through the coupling waveguide. Alternatively, cavity ring-up spectroscopy (CRUS) sensing can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh \\textit{Q}-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which might improve the data collection rate.

  11. Label-Free Biological and Chemical Sensing Using Whispering Gallery Mode Optical Resonators: Past, Present, and Future

    Directory of Open Access Journals (Sweden)

    Judith Su

    2017-03-01

    Full Text Available Sensitive and rapid label-free biological and chemical sensors are needed for a wide variety of applications including early disease diagnosis and prognosis, the monitoring of food and water quality, as well as the detection of bacteria and viruses for public health concerns and chemical threat sensing. Whispering gallery mode optical resonator based sensing is a rapidly developing field due to the high sensitivity and speed of these devices as well as their label-free nature. Here, we describe the history of whispering gallery mode optical resonator sensors, the principles behind detection, the latest developments in the fields of biological and chemical sensing, current challenges toward widespread adoption of these devices, and an outlook for the future. In addition, we evaluate the performance capabilities of these sensors across three key parameters: sensitivity, selectivity, and speed.

  12. Label-Free Biological and Chemical Sensing Using Whispering Gallery Mode Optical Resonators: Past, Present, and Future.

    Science.gov (United States)

    Su, Judith

    2017-03-08

    Sensitive and rapid label-free biological and chemical sensors are needed for a wide variety of applications including early disease diagnosis and prognosis, the monitoring of food and water quality, as well as the detection of bacteria and viruses for public health concerns and chemical threat sensing. Whispering gallery mode optical resonator based sensing is a rapidly developing field due to the high sensitivity and speed of these devices as well as their label-free nature. Here, we describe the history of whispering gallery mode optical resonator sensors, the principles behind detection, the latest developments in the fields of biological and chemical sensing, current challenges toward widespread adoption of these devices, and an outlook for the future. In addition, we evaluate the performance capabilities of these sensors across three key parameters: sensitivity, selectivity, and speed.

  13. Impact of the photorefractive and pyroelectric-electro-optic effect in lithium niobate on whispering-gallery modes.

    Science.gov (United States)

    Leidinger, Markus; Werner, Christoph S; Yoshiki, Wataru; Buse, Karsten; Breunig, Ingo

    2016-12-01

    Whispering-gallery resonators made of undoped and MgO-doped congruently grown lithium niobate are used to study electro-optic refractive index changes. Hereby, we focus on the volume photovoltaic and the pyroelectric effect, both providing an electric field driving the electro-optic effect. Our findings indicate that the light-induced photorefractive effect, combining the photovoltaic and electro-optic effect, is present only in the non-MgO-doped lithium niobate for exposure with light having wavelengths of up to 850 nm. This leads to strong resonance frequency shifts of the whispering-gallery modes. No photorefractive effect was observed in the MgO-doped material. One has to be aware that surface charges induced by the pyroelectric effect result in a similar phenomenon and are present in both materials.

  14. Application of whispering-gallery-mode optical microcavities for detection of silver nanoparticles in an aqueous medium

    Science.gov (United States)

    Samolenko, A. A.; Levin, G. G.; Lyaskovskii, V. L.; Min'kov, K. N.; Ivanov, A. D.; Bilenko, I. A.

    2017-06-01

    The results of an experimental investigation of a sensor intended for detection and measurement of concentration of nanoparticles in an aqueous medium, which is based on optical-dielectric whispering-gallery-mode microcavities, are presented. Variation of the frequency and Q-factor of the eigenmodes of the microcavity upon its interaction with silver nanoparticles is studied. It is demonstrated that this type of sensor can be used for measurement of infinitesimally low concentrations of nanoparticles.

  15. Large-scale parallel surface functionalization of goblet-type whispering gallery mode microcavity arrays for biosensing applications.

    Science.gov (United States)

    Bog, Uwe; Brinkmann, Falko; Kalt, Heinz; Koos, Christian; Mappes, Timo; Hirtz, Michael; Fuchs, Harald; Köber, Sebastian

    2014-10-15

    A novel surface functionalization technique is presented for large-scale selective molecule deposition onto whispering gallery mode microgoblet cavities. The parallel technique allows damage-free individual functionalization of the cavities, arranged on-chip in densely packaged arrays. As the stamp pad a glass slide is utilized, bearing phospholipids with different functional head groups. Coated microcavities are characterized and demonstrated as biosensors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. ZORRO: zirconium oxide resonators for all-in-one Raman and whispering-gallery-mode optical sensing.

    Science.gov (United States)

    Bontempi, N; Vassalini, I; Danesi, S; Alessandri, I

    2017-09-25

    We report the observation of whispering-gallery modes in 2 μm-sized SiO2/ZrO2 core/shell beads utilized as all-dielectric Raman enhancers. This allows us to achieve simultaneous optical and Raman ultrasensitive detection with a single spectral analysis. This opportunity opens exciting perspectives for the multimodal chemical sensing and fabrication of optical fiber devices.

  17. Silica core/conjugated polymer shell particles via seeded Knoevenagel dispersion polymerization - laser action in whispering gallery mode resonators.

    Science.gov (United States)

    Ciftci, Sibel; Mikosch, Annabel; Haehnle, Bastian; Witczak, Łukasz; Kuehne, Alexander J C

    2016-12-06

    Here, we present a seeded Knoevenagel dispersion polymerization to generate hybrid particles with a conjugated polymer shell on inorganic silica cores. This seeded dispersion polymerization facilitates the generation of core-shell particles, which exhibit whispering gallery mode lasing. The lasing threshold decreases while the spectral range of emission increases with increasing shell thickness. This novel seeded Knoevenagel dispersion polymerization opens up a facile and metal free pathway towards single particle conjugated polymer lasers on the micrometer scale.

  18. On the generation of octave-spanning optical frequency combs using monolithic whispering-gallery-mode microresonators.

    Science.gov (United States)

    Chembo, Yanne K; Yu, Nan

    2010-08-15

    Octave-spanning optical frequency combs are especially interesting in optical metrology owing to the ability of self-referencing. We report a theoretical study on the generation of octave-spanning combs in the whispering gallery modes of a microresonator. Through a modal expansion model simulation in a calcium fluoride microcavity, we show that a combination of suitable pump power, Kerr nonlinearity, and dispersion profile can lead to stable and robust octave-spanning optical frequency combs.

  19. Ultrahigh Q whispering gallery mode electro-optic resonators on a silicon photonic chip.

    Science.gov (United States)

    Soltani, Mohammad; Ilchenko, Vladimir; Matsko, Andrey; Savchenkov, Anatoliy; Schlafer, John; Ryan, Colm; Maleki, Lute

    2016-09-15

    Crystalline whispering gallery mode (WGM) electro-optic resonators made of LiNbO3 and LiTaO3 are critical for a wide range of applications in nonlinear and quantum optics, as well as RF photonics, due to their remarkably ultrahigh Q(>108) and large electro-optic coefficient. Achieving efficient coupling of these resonators to planar on-chip optical waveguides is essential for any high-yield and robust practical applications. However, it has been very challenging to demonstrate such coupling while preserving the ultrahigh Q properties of the resonators. Here, we show how the silicon photonic platform can overcome this long-standing challenge. Silicon waveguides with appropriate designs enable efficient and strong coupling to these WGM electro-optic resonators. We discuss various integration architectures of these resonators onto a silicon chip and experimentally demonstrate critical coupling of a planar Si waveguide and an ultrahigh QLiTaO3 resonator (Q∼108). Our results show a promising path for widespread and practical applications of these resonators on a silicon photonic platform.

  20. Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks

    Directory of Open Access Journals (Sweden)

    Hala Ghali

    2016-05-01

    Full Text Available Whispering Gallery Mode (WGM microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest. In this paper, WGM microdisks are used as biosensors for detection of Staphylococcus aureus. The microdisks are functionalized with LysK, a phage protein specific for staphylococci at the genus level. A binding event on the surface shifts the resonance peak of the microdisk resonator towards longer wavelengths. This reactive shift can be used to estimate the surface density of bacteria that bind to the surface of the resonator. The limit of detection of a microdisk with a Q-factor around 104 is on the order of 5 pg/mL, corresponding to 20 cells. No binding of Escherichia coli to the resonators is seen, supporting the specificity of the functionalization scheme.

  1. Single Mode ZnO Whispering-Gallery Submicron Cavity and Graphene Improved Lasing Performance.

    Science.gov (United States)

    Li, Jitao; Lin, Yi; Lu, Junfeng; Xu, Chunxiang; Wang, Yueyue; Shi, Zengliang; Dai, Jun

    2015-07-28

    Single-mode ultraviolet (UV) laser of ZnO is still in challenge so far, although it has been paid great attention along the past decades. In this work, single-mode lasing resonance was realized in a submicron-sized ZnO rod based on serially varying the dimension of the whispering-gallery mode (WGM) cavities. The lasing performance, such as the lasing quality factor (Q) and the lasing intensity, was remarkably improved by facilely covering monolayer graphene on the ZnO submicron-rod. The mode structure evolution from multimodes to single-mode was investigated systematically based on the total internal-wall reflection of the ZnO microcavities. Graphene-induced optical field confinement and lasing emission enhancement were revealed, indicating an energy coupling between graphene SP and ZnO exciton emission. This result demonstrated the response of graphene in the UV wavelength region and extended its potential applications besides many previous reports on the multifunctional graphene/semiconductor hybrid materials and devices in advanced electronics and optoelectronics areas.

  2. Whispering Gallery Mode Laser from Carbon Dot-NaCl Hybrid Crystals.

    Science.gov (United States)

    Liu, Hongzhen; Wang, Fei; Wang, Yunpeng; Mei, Jingjing; Zhao, Dongxu

    2017-05-31

    Carbon dot (CD)-NaCl hybrid crystals are obtained by incorporating the CDs into NaCl matrix through a simple process. The embedded CDs have added the luminescence centers into NaCl, and as a result, the hybrid crystals present the fluorescence centered at 510 nm under the illumination of 365 nm light. Meanwhile, the phosphorescence with an average lifetime of 314 ms is achieved after the 365 nm light was turned off. Furthermore, optical gain and lasing phenomenon has been observed from hybrid crystals. When the pump power is low, a weak spontaneous emission can be observed from the hybrid crystal, whereas the lasing action was observed under high pump power. The lasing threshold is found to be 0.08 mW and corresponding Q factor is calculated to be 447. The tiny cubic crystal in hybrid crystals offers the whispering gallery mode (WGM) resonant cavity for lasing emission. That has provided a new approach for realizing lasing materials.

  3. Whispering gallery mode resonator sensor for in situ measurements of hydrogel gelation.

    Science.gov (United States)

    Huang, Steven H; Sheth, Saahil; Jain, Era; Jiang, Xuefeng; Zustiak, Silviya P; Yang, Lan

    2018-01-08

    Whispering gallery mode (WGM) resonators are compact and ultrasensitive devices, which enable label-free sensing at the single-molecule level. Despite their high sensitivity, WGM resonators have not been thoroughly investigated for use in dynamic biochemical processes including molecular diffusion and polymerization. In this work, the first report of using WGM sensors to continuously monitor a chemical reaction (i.e. gelation) in situ in a hydrogel is described. Specifically, we monitor and quantify the gelation dynamics of polyacrylamide hydrogels using WGM resonators and compare the results to an established measurement method based on rheology. Rheology measures changes in viscoelasticity, while WGM resonators measure changes in refractive index. Different gelation conditions were studied by varying the total monomer concentration and crosslinker concentration of the hydrogel precursor solution, and the resulting similarities and differences in the signal from the WGM resonator and rheology are elucidated. This work demonstrates that WGM alone or in combination with rheology can be used to investigate the gelation dynamics of hydrogels to provide insights into their gelation mechanisms.

  4. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, Arnold, E-mail: qulaser@gmail.com [Kuang-Chi Institute of Advanced Technology, Shenzhen, 518057 (China); Kostikov, Alexander [Donbass State Engineering Academy, 84303, Kramatorsk, Donetsk (Ukraine)

    2017-03-26

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder. - Highlights: • We consider scattering of electromagnetic plane waves by two cylinders. • WGMs occur because of the presence of additional cylinder at specific location. • The accuracy for the locations is much less than required for specific values of single cylinder. • The interference of waves scattered by additional cylinders and incident on the main is responsible for the effect.

  5. Integrating Nanostructured Artificial Receptors with Whispering Gallery Mode Optical Microresonators via Inorganic Molecular Imprinting Techniques.

    Science.gov (United States)

    Hammond, G Denise; Vojta, Adam L; Grant, Sheila A; Hunt, Heather K

    2016-06-15

    The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound of interest. However, many environmental pollutants do not have corresponding biorecognition elements. Fortunately, biomimetic chemistries, such as molecular imprinting, allow for the design of artificial receptors with very high selectivity for the target. Here, we perform a proof-of-concept study to show how artificial receptors may be created from inorganic silanes using the molecular imprinting technique and paired with high-sensitivity transducers without loss of device performance. Silica microsphere Whispering Gallery Mode optical microresonators are coated with a silica thin film templated by a small fluorescent dye, fluorescein isothiocyanate, which serves as our model target. Oxygen plasma degradation and solvent extraction of the template are compared. Extracted optical devices are interacted with the template molecule to confirm successful sorption of the template. Surface characterization is accomplished via fluorescence and optical microscopy, ellipsometry, optical profilometry, and contact angle measurements. The quality factors of the devices are measured to evaluate the impact of the coating on device sensitivity. The resulting devices show uniform surface coating with no microstructural damage with Q factors above 10⁶. This is the first report demonstrating the integration of these devices with molecular imprinting techniques, and could lead to new routes to biosensor creation for environmental monitoring.

  6. Whispering Gallery Mode Resonators for Rapid Label-Free Biosensing in Small Volume Droplets

    Directory of Open Access Journals (Sweden)

    Sarah M. Wildgen

    2015-03-01

    Full Text Available Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection.

  7. Robust Whispering-Gallery-Mode Microbubble Lasers from Colloidal Quantum Dots.

    Science.gov (United States)

    Wang, Yue; Ta, Van Duong; Leck, Kheng Swee; Tan, Beng Hau Ian; Wang, Zeng; He, Tingchao; Ohl, Claus-Dieter; Demir, Hilmi Volkan; Sun, Handong

    2017-04-12

    Microlasers hold great promise for the development of photonics and optoelectronics. Among the discovered optical gain materials, colloidal quantum dots (CQDs) have been recognized as the most appealing candidate due to the facile emission tunability and solution processability. However, to date, it is still challenging to develop CQD-based microlasers with low cost yet high performance. Moreover, the poor long-term stability of CQDs remains to be the most critical issue, which may block their laser aspirations. Herein, we developed a unique but generic approach to forming a novel type of a whispering-gallery-mode (WGM) microbubble laser from the hybrid CQD/poly(methyl methacrylate) (PMMA) nanocomposites. The formation mechanism of the microbubbles was unraveled by recording the drying process of the nanocomposite droplets. Interestingly, these microbubbles naturally serve as the high-quality WGM laser resonators. By simply changing the CQDs, the lasing emission can be tuned across the whole visible spectral range. Importantly, these microbubble lasers exhibit unprecedented long-term stability (over one year), sufficient for practical applications. As a proof-of-concept, the potential of water vapor sensing was demonstrated. Our results represent a significant advance in microlasers based on the advantageous CQDs and may offer new possibilities for photonics and optoelectronics.

  8. Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks.

    Science.gov (United States)

    Ghali, Hala; Chibli, Hicham; Nadeau, Jay L; Bianucci, Pablo; Peter, Yves-Alain

    2016-05-03

    Whispering Gallery Mode (WGM) microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q) factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest. In this paper, WGM microdisks are used as biosensors for detection of Staphylococcus aureus. The microdisks are functionalized with LysK, a phage protein specific for staphylococci at the genus level. A binding event on the surface shifts the resonance peak of the microdisk resonator towards longer wavelengths. This reactive shift can be used to estimate the surface density of bacteria that bind to the surface of the resonator. The limit of detection of a microdisk with a Q-factor around 10⁴ is on the order of 5 pg/mL, corresponding to 20 cells. No binding of Escherichia coli to the resonators is seen, supporting the specificity of the functionalization scheme.

  9. Giant thermo-optical relaxation oscillations in millimeter-size whispering gallery mode disk resonators.

    Science.gov (United States)

    Diallo, Souleymane; Lin, Guoping; Chembo, Yanne K

    2015-08-15

    In this Letter, we show that giant thermo-optical oscillations can be triggered in millimeter (mm)-size whispering gallery mode (WGM) disk resonators when they are pumped by a resonant continuous-wave laser. Our resonator is an ultrahigh-Q barium fluoride cavity that features a positive thermo-optic coefficient and a negative thermo-elastic coefficient. We demonstrate for the first time, to our knowledge, that the complex interplay between these two thermic coefficients and the intrinsic Kerr nonlinearity yields very sharp slow-fast relaxation oscillations with a slow timescale that can be exceptionally large, typically of the order of 1 s. We use a time-domain model to gain understanding into this instability, and we find that both the experimental and theoretical results are in excellent agreement. The understanding of these thermal effects is an essential requirement for every WGM-related application and our study demonstrates that even in the case of mm-size resonators, such effects can still be accurately analyzed using nonlinear time-domain models.

  10. A FBG Intensity Modulation System Combined with an Optical Whispering Gallery Mode Edge Filter

    Directory of Open Access Journals (Sweden)

    Sheng-Feng Wang

    2016-03-01

    Full Text Available In this study, we demonstrated an edge filter–based fiber Bragg grating (FBG intensity modulation system to realize strain measurement. In order to establish a precise and highly sensitive intensity modulation system, we utilized a bent single-mode fiber to induce whispering gallery mode (WGM interference as an edge filter and combined that with a FBG sensor. The interference spectra of the attenuation band for the WGM edge filter were tuned by adjusting the bending radii. In addition, we compared and analyzed the signals from the proposed vibration interrogating system and a strain gauge. The measured voltage signals from the proposed interrogation system were in close agreement with measured strains of the strain gauge. The experimental results showed that when the resonant wavelength of the WGM edge filter was 1535.10 nm, the filtration was better and the noise was lower within 100 Hz. Moreover, as the frequency of piezoelectric transducer (PZT was at 400 and 1000 Hz, the better signal-to-noise ratios (SNRs of 28.54 and 25.97 were measured at wavelength 1542.05 nm of the edge filter.

  11. A Guide to Quantitative Biomarker Assay Development using Whispering Gallery Mode Biosensors.

    Science.gov (United States)

    Robison, Heather M; Bailey, Ryan C

    2017-09-14

    Whispering gallery mode (WGM) sensors are a class of powerful analytical techniques defined by the measurement of changes in the local refractive index at or near the sensor surface. When functionalized with target-specific capture agents, analyte binding can be measured with very low limits of detection. There are many geometric manifestations of WGM sensors, with chip-integrated silicon photonic devices first commercialized because of the robust, wafer-scale device fabrication, facile optical interrogation, and amenability to the creation of multiplexed sensor arrays. Using these arrays, a number of biomolecular targets have been detected in both label-free and label-enhanced assay formats. For example, sub-picomolar detection limits for multiple cytokines were achieved using an enzymatically enhanced sandwich immunoassay that showed high analyte specificity suitable for detection in complex, clinical matrices. This protocol describes a generalizable approach for the development of quantitative, multiplexed immunoassays using silicon photonic microrings as an example WGM platform. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley and Sons, Inc.

  12. Particle acceleration by wave scattering off dielectric spheres at whispering-gallery-mode resonance

    Directory of Open Access Journals (Sweden)

    Władysław Żakowicz

    2007-10-01

    Full Text Available The large electromagnetic fields, created in wave scattering near a perfect dielectric sphere at the condition of whispering-gallery-mode resonances, are investigated as driving units for high energy charged particle accelerators. For optimal trajectories passing near the scattering sphere, particle coupling with the field reduces to very short intervals, of the order of the wave period. Interacting fields can be almost 1000 times stronger than that in the incident wave. An example considered indicates that the instantaneous energy yield during this strong coupling interval is equivalent to ∼30  GeV/m, assuming the incident electric field E_{0}=100  MV/m. It was shown that the particle transverse deflection is negligible if the phase of the particle is optimal for acceleration. Hence, the acceleration process can be repeated many times. A rough estimate of the energy gain in a periodic chain of such elementary accelerating unit cells gives ΔEnergy/m≈5  GeV/m, which is several hundred times more than in contemporary operating and projected accelerators. Preliminary estimates of absorption losses in the scheme are given.

  13. Effects of Nanocylinders on the Whispering Gallery Modes in a Microcylinder

    Science.gov (United States)

    Han, Jinwoo

    2016-01-01

    Optical biosensors have been studied extensively for the detection and characterization of biological entities, such as viruses, bacteria, and biomolecules. A two-dimensional (2D) microcylinder resonator (Q∼2×105) was designed, and the effects of a nanocylinder on the whispering gallery modes (WGMs) were examined numerically. For this purpose, the finite element method with COMSOL multiphysics software was employed. The perturbation of the WGM resonances can be characterized by the shift and splitting of the resonance peaks, which varies according to the position, size, and refractive index of an embedded nanocylinder. The positional dependence shows a large splitting in the region of strong electric fields, and the size dependence shows a broad peak of the splitting at Rc=110 nm. These results are attributed to the changing degree of overlap of the WGMs with the nanocylinder. The refractive index dependences of splitting show linear behavior for a nanocylinder less than 50 nm in size, and the nonlinear behavior increases with increasing size of the nanocylinder. The optical resonator system is shown to be suitable for detecting impurity particles, which are smaller than the sizes of the node and antinode regions. PMID:27070622

  14. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Science.gov (United States)

    Siegle, T.; Remmel, M.; Krämmer, S.; Kalt, H.

    2017-09-01

    Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  15. Size-optimized polymeric whispering gallery mode lasers with enhanced sensing performance.

    Science.gov (United States)

    Krämmer, Sarah; Rastjoo, Sanaz; Siegle, Tobias; Wondimu, Sentayehu F; Klusmann, Carolin; Koos, Christian; Kalt, Heinz

    2017-04-03

    Integration of optically active materials into whispering gallery mode (WGM) cavities enables low-threshold laser emission. In contrast to their passive counterparts, the WGMs of these microlasers can be pumped and read out easily via free-space optics. The WGMs interact with the cavity environment via their evanescent field, and thus lend themselves to label-free bio-sensing. The detection limit of such sensors, given as the ratio of the resolution of the whole measurement system to the sensitivity of the WGMs, is an important figure of merit. In this work we show that the detection limit of polymeric microdisk lasers can be improved by more than a factor of seven by optimizing their radius and thickness. We use the bulk refractive index sensitivity, the magnitude of the sensor reaction towards refractive index changes of the bulk environment, to quantify the sensing performance and show that it can be enhanced while the spectral resolution is maintained. Furthermore, we investigate the effect of the size of the cavity on the quality factor and the lasing threshold in an aqueous environment, hence allowing optimization of the cavity size for enhanced sensor performance. For all considered quantities, numerically computed expectations are verified by experimental results.

  16. Whispering-gallery-mode emission from biological luminescent protein microcavity assemblies.

    Science.gov (United States)

    Humar, Matjaž; Yun, Seok Hyun

    2017-01-01

    Fluorescence and bioluminescence are widely used to study biological systems from molecular to whole organism level. However, their broadband emission is often a bottleneck for sensitive spectral measurements and multiplexing. To overcome the limitation, the emitters can be coupled with optical cavity modes to generate narrowband spectral features. Here we demonstrate several types of emitter-resonator complexes made of fluorescent or bioluminescent proteins and artificially or naturally formed optical resonators. We engineered cells to express green fluorescent protein (GFP) fused with ABHD5, which binds to oil or lipid droplets supporting whispering gallery modes (WGM). The genetically-integrated complexes feature well-defined WGM spectral peaks. We measured WGM peaks from GFP-coated BaTiO3 beads (2.56 μm in diameter) during mitosis. Finally, we demonstrate cavity-enhanced bioluminescence using luciferase-coated beads and biochemical excitation. The ability to tailor spontaneous emission by cavity resonance inside biological systems should have applications in biological sensing, imaging and cell tagging.

  17. Whispering Gallery Mode Resonators for Rapid Label-Free Biosensing in Small Volume Droplets

    Science.gov (United States)

    Wildgen, Sarah M.; Dunn, Robert C.

    2015-01-01

    Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM) resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection. PMID:25806835

  18. Whispering gallery mode lasing from hexagonal shaped layered lead iodide crystals.

    Science.gov (United States)

    Liu, Xinfeng; Ha, Son Tung; Zhang, Qing; de la Mata, Maria; Magen, César; Arbiol, Jordi; Sum, Tze Chien; Xiong, Qihua

    2015-01-27

    We report on the synthesis and optical gain properties of regularly shaped lead iodide (PbI2) platelets with thickness ranging from 10-500 nm synthesized by chemical vapor deposition methods. The as-prepared single crystalline platelets exhibit a near band edge emission of ∼ 500 nm. Whispering gallery mode (WGM) lasing from individual hexagonal shaped PbI2 platelets is demonstrated in the temperature-range of 77-210 K, where the lasing modes are supported by platelets as thin as 45 nm. The finite-difference time-domain simulation and the edge-length dependent threshold confirm the planar WGM lasing mechanism in such hexagonal shaped PbI2 platelet. Through a comprehensive study of power-dependent photoluminescence (PL) and time-resolved PL spectroscopy, we ascribe the WGM lasing to be biexcitonic in nature. Moreover, for different thicknesses of platelet, the lowest lasing threshold occurs in platelets of ∼ 120 nm, which attributes to the formation of a good Fabry-Pérot resonance cavity in the vertical direction between the top and bottom platelet surfaces that enhances the reflection. Our present study demonstrates the feasibility of planar light sources based on layered semiconductor materials and that their thickness-dependent threshold characteristic is beneficial for the optimization of layered material based optoelectronic devices.

  19. The Detection of Helicobacter hepaticus Using Whispering-Gallery Mode Microcavity Optical Sensors.

    Science.gov (United States)

    Anderson, Mark E; O'Brien, Emily C; Grayek, Emily N; Hermansen, James K; Hunt, Heather K

    2015-08-07

    Current bacterial detection techniques are relatively slow, require bulky instrumentation, and usually require some form of specialized training. The gold standard for bacterial detection is culture testing, which can take several days to receive a viable result. Therefore, simpler detection techniques that are both fast and sensitive could greatly improve bacterial detection and identification. Here, we present a new method for the detection of the bacteria Helicobacter hepaticus using whispering-gallery mode (WGM) optical microcavity-based sensors. Due to minimal reflection losses and low material adsorption, WGM-based sensors have ultra-high quality factors, resulting in high-sensitivity sensor devices. In this study, we have shown that bacteria can be non-specifically detected using WGM optical microcavity-based sensors. The minimum detection for the device was 1 × 10(4) cells/mL, and the minimum time of detection was found to be 750 s. Given that a cell density as low as 1 × 10(3) cells/mL for Helicobacter hepaticus can cause infection, the limit of detection shown here would be useful for most levels where Helicobacter hepaticus is biologically relevant. This study suggests a new approach for H. hepaticus detection using label-free optical sensors that is faster than, and potentially as sensitive as, standard techniques.

  20. Probing Stress-Induced Optical Birefringence of Glassy Polymers by Whispering Gallery Modes Light Localization

    Science.gov (United States)

    2017-01-01

    An optical resonance method for the determination of the strain- and stress-optical coefficients of optically transparent polymers is presented and exemplified for monodisperse and bidisperse molecular weight polystyrene (PS). This method employs whispering gallery modes (WGMs) resonation inside a spheroid polymeric cavity, suspended on an optical fiber taper waist, which, in turn, is used for subjecting the polymeric resonator to controlled strain conditions. The wavelength shifts of equal order transverse electric and transverse magnetic polarization WGMs are measured, as well as their relative birefringence versus applied strain. For monodisperse PS microspheroids (2 and 50 kDa) the stress-optical coefficient is negative, contrary to the results for bulk PS in the glassy state indicating different phenyl group orientation of the PS monomer with respect to the strain direction. In the bidisperse (2 and 50 kDa) spheroid with a symmetric monomer composition, local structural irregularities are probably responsible for the observed coupling between WGMs. The method possesses metrological capabilities for probing the molecular orientation of polymer-based resonators. PMID:29302634

  1. Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators.

    Science.gov (United States)

    Farnesi, Daniele; Berneschi, Simone; Cosi, Franco; Righini, Giancarlo C; Soria, Silvia; Nunzi Conti, Gualtiero

    2016-04-04

    Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given. The couplers described here are tapered fibers. Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility Χ((3)) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS). A proof of the cavity-enhanced phenomenon is given by the lack of correlation among the pump, signal and idler: a resonant mode has to exist in order to obtain the pair of signal and idler. In the case of hyperparametric oscillations (four wave mixing and stimulated anti-stokes Raman scattering), the modes must fulfill the energy and momentum conservation and, last but not least, have a good spatial overlap.

  2. All-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers.

    Science.gov (United States)

    Wienhold, T; Kraemmer, S; Wondimu, S F; Siegle, T; Bog, U; Weinzierl, U; Schmidt, S; Becker, H; Kalt, H; Mappes, T; Koeber, S; Koos, C

    2015-09-21

    We present an all-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers integrated into a microfluidic chip. The chip is entirely made from polymers, enabling the use of the devices as low-cost disposables. The microgoblet cavities feature quality factors exceeding 10(5) and are fabricated from poly(methyl methacrylate) (PMMA) using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow. In contrast to silica-based microtoroid resonators, this approach replaces technically demanding vacuum-based dry etching and serial laser-based reflow techniques by solution-based processing and parallel thermal reflow. This enables scaling to large-area substrates, and hence significantly reduces device costs. Moreover, the resonators can be fabricated on arbitrary substrate materials, e.g., on transparent and flexible polymer foils. Doping the microgoblets with the organic dye pyrromethene 597 transforms the passive resonators into lasers. Devices have lasing thresholds below 0.6 nJ per pulse and can be efficiently pumped via free-space optics using a compact and low-cost green laser diode. We demonstrate that arrays of microgoblet lasers can be readily integrated into a state-of-the-art microfluidic chip replicated via injection moulding. In a proof-of-principle experiment, we show the viability of the lab-on-a-chip via refractometric sensing, demonstrating a bulk refractive index sensitivity (BRIS) of 10.56 nm per refractive index unit.

  3. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Directory of Open Access Journals (Sweden)

    T. Siegle

    2017-09-01

    Full Text Available Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  4. Effects of Nanocylinders on the Whispering Gallery Modes in a Microcylinder

    Directory of Open Access Journals (Sweden)

    Jinwoo Han

    2016-04-01

    Full Text Available Optical biosensors have been studied extensively for the detection and characterization of biological entities, such as viruses, bacteria, and biomolecules. A two-dimensional (2D microcylinder resonator ( Q ∼ 2 × 10 5 was designed, and the effects of a nanocylinder on the whispering gallery modes (WGMs were examined numerically. For this purpose, the finite element method with COMSOL multiphysics software was employed. The perturbation of the WGM resonances can be characterized by the shift and splitting of the resonance peaks, which varies according to the position, size, and refractive index of an embedded nanocylinder. The positional dependence shows a large splitting in the region of strong electric fields, and the size dependence shows a broad peak of the splitting at R c = 110 nm . These results are attributed to the changing degree of overlap of the WGMs with the nanocylinder. The refractive index dependences of splitting show linear behavior for a nanocylinder less than 50 nm in size, and the nonlinear behavior increases with increasing size of the nanocylinder. The optical resonator system is shown to be suitable for detecting impurity particles, which are smaller than the sizes of the node and antinode regions.

  5. The Detection of Helicobacter hepaticus Using Whispering-Gallery Mode Microcavity Optical Sensors

    Directory of Open Access Journals (Sweden)

    Mark E. Anderson

    2015-08-01

    Full Text Available Current bacterial detection techniques are relatively slow, require bulky instrumentation, and usually require some form of specialized training. The gold standard for bacterial detection is culture testing, which can take several days to receive a viable result. Therefore, simpler detection techniques that are both fast and sensitive could greatly improve bacterial detection and identification. Here, we present a new method for the detection of the bacteria Helicobacter hepaticus using whispering-gallery mode (WGM optical microcavity-based sensors. Due to minimal reflection losses and low material adsorption, WGM-based sensors have ultra-high quality factors, resulting in high-sensitivity sensor devices. In this study, we have shown that bacteria can be non-specifically detected using WGM optical microcavity-based sensors. The minimum detection for the device was 1 × 104 cells/mL, and the minimum time of detection was found to be 750 s. Given that a cell density as low as 1 × 103 cells/mL for Helicobacter hepaticus can cause infection, the limit of detection shown here would be useful for most levels where Helicobacter hepaticus is biologically relevant. This study suggests a new approach for H. hepaticus detection using label-free optical sensors that is faster than, and potentially as sensitive as, standard techniques.

  6. Simultaneous cooling of coupled mechanical oscillators using whispering gallery mode resonances.

    Science.gov (United States)

    Li, Ying Lia; Millen, James; Barker, P F

    2016-01-25

    We demonstrate simultaneous center-of-mass cooling of two coupled oscillators, consisting of a microsphere-cantilever and a tapered optical fiber. Excitation of a whispering gallery mode (WGM) of the microsphere, via the evanescent field of the taper, provides a transduction signal that continuously monitors the relative motion between these two microgram objects with a sensitivity of 3 pm. The cavity enhanced optical dipole force is used to provide feedback damping on the motion of the micron-diameter taper, whereas a piezo stack is used to damp the motion of the much larger (up to 180 μm in diameter), heavier (up to 1.5 × 10(-7) kg) and stiffer microsphere-cantilever. In each feedback scheme multiple mechanical modes of each oscillator can be cooled, and mode temperatures below 10 K are reached for the dominant mode, consistent with limits determined by the measurement noise of our system. This represents stabilization on the picometer level and is the first demonstration of using WGM resonances to cool the mechanical modes of both the WGM resonator and its coupling waveguide.

  7. Integrating Nanostructured Artificial Receptors with Whispering Gallery Mode Optical Microresonators via Inorganic Molecular Imprinting Techniques

    Directory of Open Access Journals (Sweden)

    G. Denise Hammond

    2016-06-01

    Full Text Available The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound of interest. However, many environmental pollutants do not have corresponding biorecognition elements. Fortunately, biomimetic chemistries, such as molecular imprinting, allow for the design of artificial receptors with very high selectivity for the target. Here, we perform a proof-of-concept study to show how artificial receptors may be created from inorganic silanes using the molecular imprinting technique and paired with high-sensitivity transducers without loss of device performance. Silica microsphere Whispering Gallery Mode optical microresonators are coated with a silica thin film templated by a small fluorescent dye, fluorescein isothiocyanate, which serves as our model target. Oxygen plasma degradation and solvent extraction of the template are compared. Extracted optical devices are interacted with the template molecule to confirm successful sorption of the template. Surface characterization is accomplished via fluorescence and optical microscopy, ellipsometry, optical profilometry, and contact angle measurements. The quality factors of the devices are measured to evaluate the impact of the coating on device sensitivity. The resulting devices show uniform surface coating with no microstructural damage with Q factors above 106. This is the first report demonstrating the integration of these devices with molecular imprinting techniques, and could lead to new routes to biosensor creation for environmental monitoring.

  8. Optical signal processing and tracking of whispering gallery modes in real-time for sensing applications

    Science.gov (United States)

    Ali, Amir R.; Afifi, Amr N.; Taha, Hazem

    2017-05-01

    A novel approach for tracking of whispering gallery modes (WGM) in real-time for dielectric cavities used in sensing application is presented in this paper. Real-time tracking for the shifts of the WGM can be used to measure the physical quantity of interest precisely, under high repetition rates. The tracking algorithm is based on cross-correlation signal processing technique which has been proved to be accurate in WGM shifts detection. In order to achieve portability, the aforementioned real-time algorithm is implemented using a single-board re-configurable input-output hardware. The hardware platform used combines a real-time processor and a field programmable gate array (FPGA), it also allows for data exchange between them. The tracking algorithm's accuracy and real-time behavior is verified by preforming simulations based on experiments conducted on the dielectric cavity, where the cavity is used as a force sensor measuring mechanical compression. The light from a laser diode is tuned with rates up to 10 kHz and then tangentially coupled into the cavity to excite the WGM. Results show that shifts of the WGM are tracked by the algorithm providing real-time force readings.

  9. Enhanced reflectance X-ray absorption fine structure sensitivity using a whispering-gallery waveguide

    CERN Document Server

    Chernov, V A; Kovalenko, N V; Zolotarev, K V

    2000-01-01

    A new technique of reflectance X-ray absorption fine structure (REFL-XAFS) utilizing waveguides where X-rays are reflected many times along the waveguide surface is discussed. The multiple total reflection (MTR) phenomenon highly increases X-ray interaction with the waveguide surface and hence offers higher sensitivity compared to conventional (single reflection) REFL-XAFS. On the one hand, this technique is a direct structural method for characterizing waveguides (e.g. capillaries) where the application of other methods is very difficult. On the other hand, the conventional thin wafer can be transformed to a whispering-gallery (WG) waveguide by bending to a curved mirror. Ray tracing calculations demonstrate that the WG waveguide is very suitable for REFL-XAFS measurements. This method was experimentally realized for a cylindrically bent silica wafer with the surface covered with a GeO sub 2 monolayer. The Ge K-edge REFL-XAFS measurements were performed using both MTR and conventional techniques. The MTR tec...

  10. Investigation of plasmonic whispering-gallery mode characteristics for graphene monolayer coated dielectric nanodisks.

    Science.gov (United States)

    Zhao, Jing; Qiu, Weibin; Huang, Yixin; Wang, Jia-Xian; Kan, Qiang; Pan, Jiao-Qing

    2014-10-01

    In this Letter, we theoretically studied high-quality (Q) factor plasmonic whispering-gallery modes (WGMs) with ultrasmall mode volumes in graphene monolayer coated semiconductor nanodisks in the mid-infrared range. The influence of the chemical potential, the relaxation time of graphene, and the radius of the nanodisk on the cavity Q factor and the mode volume was numerically investigated. The numerical simulations showed that the plasmonic WGMs excited in this cavity had a deep subwavelength mode volume of 1.4×10(-5)(λ(0)/2n)(3), a cavity Q factor as high as 266 at a temperature lower than 250 K, and, consequently, a large Purcell factor of ∼1.2×10(7) when the chemical potential and relaxation time were assumed to be 0.9 eV and 1.4 ps, respectively. The results provide a possible application of plasmonic WGMs in the integration of nano-optoelectronic devices based on graphene.

  11. Whispering Gallery Mode Resonances from Ge Micro-Disks on Suspended Beams

    Directory of Open Access Journals (Sweden)

    Abdelrahman Zaher Al-Attili

    2015-05-01

    Full Text Available Ge is considered to be one of the most promising materials for realizing full monolithic integration of a light source on a silicon (Si photonic chip. Tensile-strain is required to convert Ge into an optical gain material and to reduce the pumping required for population inversion. Several methods of strain application to Ge are proposed in literature, of which the use of free-standing beams fabricated by micro-electro-mechanical systems (MEMS processes are capable of delivering very high strain values. However, it is challenging to make an optical cavity within free-standing Ge beams, and here, we demonstrate the fabrication of a simple cavity while imposing tensile strain by suspension using Ge-On-Insulator (GOI wafers. Ge micro-disks are made on top of suspended SiO$_{2}$ beams by partially removing the supporting Si substrate. According to Raman spectroscopy, a slight tensile strain was applied to the Ge disks through the bending of the SiO2 beams. Whispering-Gallery-Mode (WGM resonances were observed from a disk with a diameter of 3um, consistent with the finite-domain time-difference simulations. The quality (Q factor was 192, and upon increasing the pumping power, the Q-factor was degraded due to the red-shift of Ge direct-gap absorption edge caused by heating.

  12. Polarization-Selective Out-Coupling of Whispering-Gallery Modes

    Science.gov (United States)

    Sedlmeir, Florian; Foreman, Matthew R.; Vogl, Ulrich; Zeltner, Richard; Schunk, Gerhard; Strekalov, Dmitry V.; Marquardt, Christoph; Leuchs, Gerd; Schwefel, Harald G. L.

    2017-02-01

    Whispering-gallery mode (WGM) resonators are an important platform for linear, nonlinear, and quantum optical experiments. In such experiments, independent control of in-coupling and out-coupling rates to different modes can lead to higher conversion efficiencies and greater flexibility in the generation of nonclassical states based on parametric down-conversion. In this work, we introduce a scheme that enables selective out-coupling of WGMs belonging to a specific polarization family, while the orthogonally polarized modes remain largely unperturbed. Our technique utilizes material birefringence in both the resonator and the coupler such that a negative (positive) birefringence allows for polarization-selective coupling to TE (TM) WGMs. We formulate a refined coupling condition suitable for describing the case where the refractive indices of the resonator and the coupler are almost the same, from which we derive a criterion for polarization-selective coupling. Finally, we experimentally demonstrate our proposed method using a lithium niobate disk resonator coupled to a lithium niobate prism, where we show a 22-dB suppression of coupling to TM modes relative to TE modes.

  13. Microstructured optical fiber for multichannel sensing based on Fano resonance of the whispering gallery modes.

    Science.gov (United States)

    Lin, Wei; Zhang, Hao; Chen, Shih-Chi; Liu, Bo; Liu, Yan-Ge

    2017-01-23

    We present the design and theoretical demonstration of a microstructured optical fiber (MOF) for multichannel sensing applications based on the Fano resonance among the different whispering-gallery modes (WGMs) propagating in the MOF. The proposed MOF consists of a number of capillary channels with different diameters inside a tubular frame. When the phases of the WGMs in the capillary channels and the frame are matched, the Fano resonance will occur and the resonant peaks can be observed in the output spectrum of the tubular frame resonator. Sensing signals from the individual channels can be detected by measuring the central wavelengths of the corresponding Fano resonant peaks. To demonstrate the practicality, we study a dual-channel MOF for bio-sensing applications, i.e., detecting the refractive index variation in biological samples. In the analysis, we have shown that channel 1 and 2 achieve a sensitivity of 29.0557 nm/RIU (refractive index unit) and 22.9160 nm/RIU in the TE mode; and 16.0694 nm/RIU and 13.3181 nm/RIU in the TM mode respectively, when the refractive index of the biological samples varies between 1.330 and 1.345. The new MOF can be a compact, flexible, and low-cost solution for a variety of applications including multichannel bio/chemical sensing, multi-microcavity laser, and tunable photonics devices.

  14. Non-linear fluorescence excitation of Rhodamine 6G and TRITC labeled IgG in whispering gallery mode microresonators

    Science.gov (United States)

    Pastells, Carme; Marco, M. Pilar; Merino, David; Loza-Alvarez, Pablo; Pasquardini, Laura; Pederzolli, Cecilia; Farnesi, Daniele; Berneschi, Simone; Righini, Giancarlo C.; Nunzi Conti, Gualtiero; Soria Huguet, Silvia

    2015-03-01

    We report the non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a microspherical whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also tested the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are tetramethyl rhodamine isothiocyanate and Rhodamine 6G. All measurements were performed in a modified confocal microscope.

  15. Surface plasmon resonance-based refractometry using whispering gallery modes in bent metalized single-mode optical fibers

    Science.gov (United States)

    Dyshlyuk, Anton V.; Mitsai, Evgeniy V.; Vitrik, Oleg B.

    2017-09-01

    The work is devoted to the numerical and experimental study of surface plasmon resonance in a bent single-mode optical fiber with metalized cladding. It was shown that with a proper combination of metal film thickness and bend radius one can achieve coupling between fundamental and surface plasmon modes through an intermediary of whispering gallery mode supported by the bent fiber's optical cladding. This brings about a dip in the transmission spectrum of the fiber at the resonant wavelength which depends strongly on the external medium refractive index, so that refractometric measurements can be performed with a sensitivity of ˜5 μm/RIU and resolution ˜4.10-6.

  16. Subwavelength silicon disk whispering-gallery-mode microcavities for size-dependent nanoparticles detection in the mid-infrared

    Science.gov (United States)

    Dionne, Jeffrey; Ashwath, Harshitha; Kuznetsova, Lyuba

    2017-05-01

    Three-dimensional finite-element-method numerical simulations are used to investigate a size-dependent sensing technique by observing the effects that a spherical nanoparticle had on the frequency resonances of whispering-gallery modes of a subwavelength silicon microdisk. Results show that the observed spectral shift varies significantly (˜2 to 8 nm) for the TM optical mode with an attached nanoparticle with radii between 150 and 400 nm. This frequency shift size-dependence makes it possible to identify viruses of different sizes by the resonant frequency change in the transmission spectrum in the mid-infrared.

  17. Measurements of the Complex Permittivity of Liquid Helium-4 in the Millimeter Wave Range by a Whispering Gallery Mode Resonator

    Science.gov (United States)

    Smorodin, A. V.; Rybalko, A. S.; Konstantinov, D.

    2017-06-01

    We report an experimental study of the electrical properties of liquid helium-4 in the temperature range 1.2-3 K. The experiment is carried out in the millimeter wave range using a whispering gallery mode dielectric resonator, and the complex permittivity of liquid helium is extracted from the data using the resonant perturbation method. The results for the temperature dependence of the dielectric constant are consistent with the previous studies. In addition, we find strong enhancement of the loss tangent around the superfluid transition temperature.

  18. Controllable fabrication and optical properties of Sn-doped ZnO hexagonal microdisk for whispering gallery mode microlaser

    Directory of Open Access Journals (Sweden)

    J. Dai

    2013-09-01

    Full Text Available We report a controllable method for fabricating hexagonal Sn doped ZnO microdisks. The photoluminescence mechanism of the Sn doped ZnO microdisks is investigated, the defect emission is attributed to the singly charged oxygen vacancy. Under the excitation of a femtosecond pulsed laser with a wavelength of 325 nm, exciton-exciton collision process is clearly demonstrated, and amplified spontaneous emission is further realized under strong excitation. Using the perfect hexagonal symmetric structure of the Sn doped ZnO microdisks, the whispering-gallery mode lasing with high quality factor and fine mode structure is obtained from a single microdisk.

  19. Mode conversion in a tapered fiber via a whispering gallery mode resonator and its application as add/drop filter.

    Science.gov (United States)

    Huang, Ligang; Wang, Jie; Peng, Weihua; Zhang, Wending; Bo, Fang; Yu, Xuanyi; Gao, Feng; Chang, Pengfa; Song, Xiaobo; Zhang, Guoquan; Xu, Jingjun

    2016-02-01

    Based on the conversion between the fundamental mode (LP01) and the higher-order mode (LP11) in a tapered fiber via a whispering gallery mode resonator, an add/drop filter was proposed and demonstrated experimentally, in which the resonator only interacted with one tapered fiber, rather than two tapered fibers as in conventional configurations. The filter gains advantages of easy alignment and low scattering loss over the other filters based on tapered fiber and resonator, and will be useful in application.

  20. THz Pyro-Optical Detector Based on LiNbO3 Whispering Gallery Mode Microdisc Resonator

    Science.gov (United States)

    Cosci, Alessandro; Cerminara, Matteo; Nunzi Conti, Gualtiero; Soria, Silvia; Righini, Giancarlo C.; Pelli, Stefano

    2017-01-01

    This study analyzes the capabilities of a LiNbO3 whispering gallery mode microdisc resonator as a potential bolometer detector in the THz range. The resonator is theoretically characterized in the stationary regime by its thermo-optic and thermal coefficients. Considering a Q-factor of 107, a minimum detectable power of 20 μW was evaluated, three orders of magnitude above its noise equivalent power. This value opens up the feasibility of exploiting LiNbO3 disc resonators as sensitive room-temperature detectors in the THz range. PMID:28134857

  1. Bio-optical sensor for brain activity measurement based on whispering gallery modes

    Science.gov (United States)

    Ali, Amir R.; Massoud, Yasmin M.

    2017-05-01

    In this paper, a high-resolution bio-optical sensor is developed for brain activity measurement. The aim is to develop an optical sensor with enough sensitivity to detect small electric field perturbations caused by neuronal action potential. The sensing element is a polymeric dielectric micro-resonator fabricated in a spherical shape with a few hundred microns in diameter. They are made of optical quality polymers that are soft which make them mechanically compatible with tissue. The sensors are attached to or embedded in optical fibers which serve as input/output conduits for the sensors. Hundreds or even thousands of spheres can be attached to a single fiber to detect and transmit signals at different locations. The high quality factor for the optical resonator makes it significantly used in such bio-medical applications. The sensing phenomenon is based on whispering gallery modes (WGM) shifts of the optical sensor. To mimic the brain signals, the spherical resonator is immersed in a homogeneous electrical field that is created by applying potential difference across two metallic plates. One of the plates has a variable voltage while the volt on the other plate kept fixed. Any small perturbations of the potential difference (voltage) lead to change in the electric field intensity. In turn the sensor morphology will be affected due to the change in the electrostriction force acting on it causing change in its WGM. By tracking these WGM shift on the transmission spectrum, the induced potential difference (voltage change) could be measured. Results of a mathematical model simulation agree well with the preliminary experiments. Also, the results show that the brain activity could be measured using this principle.

  2. Intensity fluctuations of erbium-doped whispering gallery mode lasers (Conference Presentation)

    Science.gov (United States)

    Féron, Patrice; Ceppe, Jean-Baptiste; Dumeige, Yannick; Mortier, Michel S.

    2017-02-01

    Micro spherical resonators have attracted significant attention in recent years due to their interesting optical properties and the range of applications for which they can be used. Most of the publications dedicated to micro spherical Laser are devoted to lasing effects in different materials where the spectral properties of the emission depends on (i) the choice of dopant (e.g. Er3+, Yb3+, Tm3+) and (ii) the host matrix (e.g. silica, fluoride, phosphate or telluride glass) in which the dopant is embedded. Yet, the dynamics of theses Lasers are still to be studied. This paper shows experimental results on the amplitude fluctuations of a Whispering Gallery Mode Laser, also known as relative intensity noise (RIN). It gives information about the dynamics inside the cavity, such as photon lifetime, effective pumping rate and noise sources. We use as active medium Er3+ doped fluoride ZBLALiP glass and also industrial IOG-1 Yb3+- Er3+ co-doped phosphate glass. Theses glasses are well adapted to the development of micro spherical Laser operating in the infrared region, in particular with emission wavelengths falling respectively in the C-band and C+L band. We have observed that the RIN can provide insurance about the emission of the Laser. Moreover, we have shown that a single-mode emission comes with the presence of multiple harmonics of the relaxation frequency, which is the signature of a Laser with high noise levels. In this particular case, the second and higher orders of intensity fluctuations cannot be neglected any longer in the small-signal analysis.

  3. Microsensors based on a whispering gallery mode in AlGaN microdisks undercut by hydrogen-environment thermal etching.

    Science.gov (United States)

    Kouno, Tetsuya; Sakai, Masaru; Takeshima, Hoshi; Suzuki, Sho; Kikuchi, Akihiko; Kishino, Katsumi; Hara, Kazuhiko

    2017-04-20

    AlGaN microdisks were fabricated via a top-down process using electron-beam lithography, inductively coupled plasma reactive-ion etching, and hydrogen-environment thermal etching from commercial epitaxial wafers with a 100-300 nm thick AlGaN layer grown on a c-plane GaN layer by metal-organic chemical vapor deposition. The hydrogen-environment thermal etching performed well in undercutting the AlGaN microdisks owing to the selective etching for the GaN layer. The AlGaN microdisks acted as the whispering gallery mode (WGM) optical microresonators, exhibiting sharp resonant peaks in room temperature photoluminescence spectra. The evanescent component of the whispering gallery mode (WGM) is influenced by the ambient condition of the microdisk, resulting in the shift of the resonant peaks. The phenomenon is considered to be used for microsensors. Using the WGM in the AlGaN microdisks, we demonstrated microsensors and a microsensor system, which can potentially be used to evaluate biological and chemical actions in a microscale area in real time.

  4. Second-harmonic generation using 4-quasi-phasematching in a GaAs whispering-gallery-mode microcavity.

    Science.gov (United States)

    Kuo, Paulina S; Bravo-Abad, Jorge; Solomon, Glenn S

    2014-01-01

    The 4 crystal symmetry in materials such as GaAs can enable quasi-phasematching for efficient optical frequency conversion without poling, twinning or other engineered domain inversions. 4 symmetry means that a 90° rotation is equivalent to a crystallographic inversion. Therefore, when light circulates about the 4 axis, as in GaAs whispering-gallery-mode microdisks, it encounters effective domain inversions that can produce quasi-phasematching. Microdisk resonators also offer resonant field enhancement, resulting in highly efficient frequency conversion in micrometre-scale volumes. These devices can be integrated in photonic circuits as compact frequency convertors, sources of radiation or entangled photons. Here we present the first experimental observation of second-harmonic generation in a whispering-gallery-mode microcavity utilizing -quasi-phasematching. We use a tapered fibre to couple into the 5-μm diameter microdisk resonator, resulting in a normalized conversion efficiency η≈5 × 10(-5)mW(-1). Simulations indicate that when accounting for fibre-cavity scattering, the normalized conversion efficiency is η≈3 × 10(-3)mW(-1).

  5. Observation of defect-assisted enhanced visible whispering gallery modes in ytterbium-doped ZnO microsphere

    Science.gov (United States)

    Khanum, Rizwana; Moirangthem, Rakesh S.; Das, Nayan Mani

    2017-06-01

    Smooth surfaced and crystalline undoped and ytterbium doped zinc oxide (ZnO) microspheres having an approximate size of 3-5 μm were synthesized by hydrothermal process. Out of these microspheres, a single microparticle was chosen and engaged as a whispering gallery wave microresonator. The defect induced luminescence from an individual ZnO microsphere was investigated with micro-photoluminescence measurement in the spectral range of 565 to 740 nm under the excitation of a green laser having a centered wavelength at 532 nm. The defects-related emissions from a single ZnO microsphere show optical resonance peaks so-called "whispering gallery modes" (WGMs) which are confirmed with the theoretical calculation. Further, ZnO microspheres were chemically doped with the different molar percentages of Ytterbium (Yb), and enhancement in their emission properties was investigated. Our experimental results show that ZnO microspheres with 0.5 mol. % doping of Yb gives the strongest optical emission and has highest Q-factor which can be employed in the development of WGM based optical biosensor or laser.

  6. Second-harmonic generation using -quasi-phasematching in a GaAs whispering-gallery-mode microcavity

    Science.gov (United States)

    Kuo, Paulina S.; Bravo-Abad, Jorge; Solomon, Glenn S.

    2014-01-01

    The crystal symmetry in materials such as GaAs can enable quasi-phasematching for efficient optical frequency conversion without poling, twinning or other engineered domain inversions. symmetry means that a 90° rotation is equivalent to a crystallographic inversion. Therefore, when light circulates about the axis, as in GaAs whispering-gallery-mode microdisks, it encounters effective domain inversions that can produce quasi-phasematching. Microdisk resonators also offer resonant field enhancement, resulting in highly efficient frequency conversion in micrometre-scale volumes. These devices can be integrated in photonic circuits as compact frequency convertors, sources of radiation or entangled photons. Here we present the first experimental observation of second-harmonic generation in a whispering-gallery-mode microcavity utilizing -quasi-phasematching. We use a tapered fibre to couple into the 5-μm diameter microdisk resonator, resulting in a normalized conversion efficiency η≈5 × 10−5 mW−1. Simulations indicate that when accounting for fibre-cavity scattering, the normalized conversion efficiency is η≈3 × 10−3 mW−1. PMID:24434576

  7. Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

    Science.gov (United States)

    Ioppolo, Tindaro; Ötügen, Volkan; Ayaz, Ulas

    2013-01-01

    Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential. The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 μm) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere

  8. Sensing operations based on hexagonal GaN microdisks acting as whispering-gallery mode optical microcavities.

    Science.gov (United States)

    Kouno, Tetsuya; Sakai, Masaru; Kishino, Katsumi; Hara, Kazuhiko

    2015-06-15

    Using room temperature photoluminescence measurements, we have demonstrated a sensing operation based on hexagonal GaN microdisks with a side length of approximately 1.5 μm that acted as optical microcavities. In the experiment, the optical microresonant systems based on the whispering-gallery mode (WGM) in the microdisks were affected by their ambient conditions, resulting in shifts of the lasing wavelength by varying the mixing ratios of isopropanol and o-xylene. We also obtained such shifts for aqueous solutions with varying sucrose concentrations. In addition, we demonstrated that tiny waterborne particles can be detected using a microdisk. These results indicate that the WGM in the hexagonal GaN microdisks potentially can be used to develop optical microbiosensors that can evaluate a limited area with a radius of 1-2 μm.

  9. Integrating a DNA Strand Displacement Reaction with a Whispering Gallery Mode Sensor for Label-Free Mercury (II) Ion Detection.

    Science.gov (United States)

    Wu, Fengchi; Wu, Yuqiang; Niu, Zhongwei; Vollmer, Frank

    2016-07-29

    Mercury is an extremely toxic chemical pollutant of our environment. It has attracted the world's attention due to its high mobility and the ease with which it accumulates in organisms. Sensitive devices and methods specific for detecting mercury ions are, hence, in great need. Here, we have integrated a DNA strand displacement reaction with a whispering gallery mode (WGM) sensor for demonstrating the detection of Hg(2+) ions. Our approach relies on the displacement of a DNA hairpin structure, which forms after the binding of mercury ions to an aptamer DNA sequence. The strand displacement reaction of the DNA aptamer provides highly specific and quantitative means for determining the mercury ion concentration on a label-free WGM sensor platform. Our approach also shows the possibility for manipulating the kinetics of a strand displacement reaction with specific ionic species.

  10. Multiphoton absorption-induced optical whispering-gallery modes in ZnO microcavities at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dai, J; Xu, C X; Guo, J Y; Li, Z H [State Key Laboratory of Bioelectronics, and Advanced Photonics Center, Southeast University, Nanjing 210096 (China); Sun, L X; Chen, Z H, E-mail: xcxseu@seu.edu.cn [State Key Laboratory of Surface Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China)

    2011-01-19

    Ultralong ZnO microrods with a perfect hexagonal cross section were synthesized on a large scale by the vapour phase transport method and were employed as a whispering-gallery mode (WGM) cavity to realize optical resonance and lasing. An individual ZnO microrod was selected to investigate the multiphoton absorption-induced optical behaviours based on the enhancement of the nonlinear optical interaction in the WGM cavity. Three-photon absorption-induced UV lasing, second-harmonic generation and defect-related visible emission simultaneously present distinct WGMs under the excitation of femtosecond laser pulses at 1200 nm. When the pump laser was changed to 1240 nm, four-photon absorption-induced WGM lasing was observed. The characteristics and generation process of the above resonant signals were investigated in detail.

  11. Relationship between height and width of resonance peaks in a whispering gallery mode resonator immersed in water and sucrose solutions

    Science.gov (United States)

    Teraoka, Iwao; Yao, Haibei; Huiyi Luo, Natalie

    2017-06-01

    We employed a recently developed whispering gallery mode (WGM) dip sensor made of silica to obtain spectra for many resonance peaks in water and solutions of sucrose at different concentrations and thus having different refractive indices (RI). The apparent Q factor was estimated by fitting each peak profile in the busy resonance spectrum by a Lorentzian or a sum of Lorentzians. A plot of the Q factor as a function the peak height for all the peaks analyzed indicates a straight line with a negative slope as the upper limit, for each of water and the solutions. A coupling model for a resonator and a pair of fiber tapers to feed and pick up light, developed here, supports the presence of the upper limit. We also found that the round-trip attenuation of WGM was greater than the one estimated from light absorption by water, and the difference increased with the concentration of sucrose.

  12. Laser-frequency locking to a whispering-gallery-mode cavity by spatial interference of scattered light.

    Science.gov (United States)

    Zullo, R; Giorgini, A; Avino, S; Malara, P; De Natale, P; Gagliardi, G

    2016-02-01

    We present a simple and effective method for frequency locking a laser source to a free-space-coupled whispering-gallery-mode cavity. The scheme relies on the interference of spatial modes contained in the light scattered by the cavity, where low- and high-order modes are simultaneously excited. A dispersion-shaped signal proportional to the imaginary component of the resonant optical field is simply generated by spatial filtering of the scattered light. Locking of a diode laser to the equatorial modes of a liquid droplet resonator is demonstrated using this scheme, and its performance is compared to the Pound-Drever-Hall technique. This new approach makes laser-frequency locking straightforward and shows a number of advantages, including robustness, low cost, and no need for sophisticated optical and electronic components.

  13. Integration of digital microfluidics with whispering-gallery mode sensors for label-free detection of biomolecules.

    Science.gov (United States)

    Wondimu, Sentayehu F; von der Ecken, Sebastian; Ahrens, Ralf; Freude, Wolfgang; Guber, Andreas E; Koos, Christian

    2017-05-16

    We present a multi-sensor chip comprising an array of whispering-gallery mode (WGM) micro-goblet lasers integrated into a digital microfluidic (DMF) system. In contrast to earlier demonstrations, the lasers are fabricated from dye-doped poly-methyl methacrylate (PMMA) at low cost using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow techniques. Pumping and read-out of the devices is accomplished via simple free-space optics, thereby allowing large-scale sensor arrays to be addressed. We demonstrate the viability of the system by bulk refractive index-sensing and by measuring the specific binding of streptavidin to a biotinylated sensor surface. This is the first time that optical cavities are used for label-free detection of biomolecules in a DMF system. This approach can be extended to a versatile detector platform that targets a wide range of clinically relevant biomolecules.

  14. Light-controlled microwave whispering-gallery-mode quasi-optical resonators at 50W LED array illumination

    Directory of Open Access Journals (Sweden)

    V. B. Yurchenko

    2015-08-01

    Full Text Available We present experimental observations of light-controlled resonance effects in microwave whispering-gallery-mode quasi-optical dielectric-semiconductor disk resonators in the frequency band of 5 GHz to 20 GHz arising due to illumination from a light emitting diode (LED of 50W power range. We obtain huge enhancement of photo-sensitivity (growing with the resonator Q-factor that makes light-microwave interaction observable with an ordinary light (no laser at conventional brightness (like an office lighting in quasi-optical microwave structures at rather long (centimeter-scale wavelength. We also demonstrate non-conventional photo-response of Fano resonances when the light suppresses one group of resonances and enhances another group. The effects could be used for the optical control and quasi-optical switching of microwave propagation through either one or another frequency channel.

  15. Graphene-supported plasmonic whispering-gallery mode in a metal-coated microcavity for sensing application with ultrahigh sensitivity

    Science.gov (United States)

    Fan, Huibo; Xia, Changquan; Fan, Li; Wang, Lichun; Shen, Mingya

    2018-03-01

    We propose and numerically investigate the plasmonic whispering-gallery mode (WGM) with high-quality (Q) factor (as high as 285) and ultra-small mode volume (as low as 0 . 04 μm3) in the hybrid plasmonic microcavity with a sandwiched and electrically controlled graphene. The theoretical results present that the resonant wavelength of hybrid plasmonic microcavity dramatically changes and the corresponding intrinsic loss exhibits a distinct peak by electrically adjusting the permittivity of graphene around the epsilon-near-zero (ENZ) point. The influence of graphene with different layers on the characteristic of hybrid plasmonic microcavity is also analyzed. As a potential application, the plasmonic WGM microcavity with the sandwiched graphene could be applied for a refractometer with the sensitivity of higher than 1000 nm per refraction index unit (nm/RIU), and large figure of merit. The sensitivity can also be tuned by the electrically controlled graphene.

  16. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    CERN Document Server

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  17. Whispering Gallery mode ESR spectroscopy and parameters measurement in single crystal SrLaAlO4 at millikelvin temperature

    Science.gov (United States)

    Hosain, M. A.; Le Floch, J.-M.; Krupka, J.; Tobar, M. E.

    2017-08-01

    A cylindrical single crystal SrLaAlO4 Whispering Gallery mode dielectric resonator was cooled to millikelvin temperature using a dilution refrigerator. By controlling a DC-magnetic field, impurity ions' spins were coupled to a variety of modes allowing the measurement of hybrid spin-photon systems. This Electron Spin Resonance mapping technique allowed us to detect Cu2+,Fe3+ and Mn4+ impurity ions (at the level of parts per million (ppm) to parts per billion (ppb)), verified by the measurement of the spin parameters along with their site symmetry. Whispering Gallery modes exhibited Q-factors ⩾105 at a temperature less than 20mK , allowing sensitive spectroscopy with high precision. Measured hyperfine line constants of the Cu2+ ion shows different parallel g-factors, g‖Cu , of 2.526, 2.375, 2.246 and 2.142 . The spin-orbit coupling constant of the Cu2+ ion was determined to be λ ≃ - 635cm-1 . The low-spin state Fe3+ ion's measured parallel g-factor, g‖Fe , of 2.028 reveals tetragonal anisotropy. The Mn4+ ion is identified in the lattice, producing hyperfine structure with high-valued g-factors,g‖Mn , of 7.789, 7.745, 7.688, 7.613, 7.5304 and 7.446 . The hyperfine structures of the Cu2+ and Mn4+ ions show broadening of about 79G between 9.072GHz and 10.631GHz , and 24.5G broadening between 9.072GHz and 14.871GHz , respectively.

  18. Dynamic Self-Referencing Approach to Whispering Gallery Mode Biosensing and Its Application to Measurement within Undiluted Serum.

    Science.gov (United States)

    Reynolds, Tess; François, Alexandre; Riesen, Nicolas; Turvey, Michelle E; Nicholls, Stephen J; Hoffmann, Peter; Monro, Tanya M

    2016-04-05

    Biosensing within complex biological samples requires a sensor that can compensate for fluctuations in the signal due to changing environmental conditions and nonspecific binding events. To achieve this, we developed a novel self-referenced biosensor consisting of two almost identically sized dye-doped polystyrene microspheres placed on adjacent holes at the tip of a microstructured optical fiber (MOF). Here self-referenced biosensing is demonstrated with the detection of Neutravidin in undiluted, immunoglobulin-deprived human serum samples. The MOF allows remote excitation and collection of the whispering gallery modes (WGMs) of the microspheres while also providing a robust and easy to manipulate dip-sensing platform. By taking advantage of surface functionalization techniques, one microsphere acts as a dynamic reference, compensating for nonspecific binding events and changes in the environment (such as refractive index and temperature), while the other microsphere is functionalized to detect a specific interaction. The almost identical size allows the two spheres to have virtually identical refractive index sensitivity and surface area, while still having discernible WGM spectra. This ensures their responses to nonspecific binding and environmental changes are almost identical, whereby any specific changes, such as binding events, can be monitored via the relative movement between the two sets of WGM peaks.

  19. Covert Photonic Barcodes Based on Light Controlled Acidichromism in Organic Dye Doped Whispering-Gallery-Mode Microdisks.

    Science.gov (United States)

    Gao, Zhenhua; Wei, Cong; Yan, Yongli; Zhang, Wei; Dong, Haiyun; Zhao, Jinyang; Yi, Jun; Zhang, Chunhuan; Li, Yong Jun; Zhao, Yong Sheng

    2017-08-01

    Photonic barcodes with a small footprint have demonstrated a great value for multiplexed high-throughput bioassays and tracking systems. Attempts to develop coding technology tend to focus on the generation of featured barcodes both with high coding capacity and accurate recognition. In this work, a strategy to design photonic barcodes is proposed based on whispering-gallery-mode (WGM) modulations in dye-doped microdisk resonant cavities, where each modulated photoluminescence spectrum constitutes the fingerprint of a corresponding microdisk. The WGM-based barcodes can achieve infinite encoding capacity through tuning the dimensions of the microdisks. These photonic barcodes can be well disguised and decoded based on the light controlled proton release and acidichromism of the organic materials, which are essential to fulfill the functions of anti-counterfeiting, information security, and so on. The results will pave an avenue to new types of flexible WGM-based components for optical data recording and security labels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Maximization of the optical intra-cavity power of whispering-gallery mode resonators via coupling prism.

    Science.gov (United States)

    Santamaría-Botello, G A; García Muñoz, L E; Sedlmeir, F; Preu, S; Segovia-Vargas, D; Atia Abdalmalak, K; Llorente Romano, S; García Lampérez, A; Malzer, S; Döhler, G H; Schwefel, H G L; Weber, H B

    2016-11-14

    In this paper, a detailed description of the optical coupling into a Whispering Gallery Mode (WGM) resonator through a prism via frustrated total internal reflection (FTIR) is presented. The problem is modeled as three media with planar interfaces and closed expressions for FTIR are given. Then, the curvature of the resonator is taken into account and the mode overlap is theoretically studied. A new analytical expression giving the optimal geometry of a disc-shaped or ring-shaped resonator for maximizing the intra-cavity circulating power is presented. Such expression takes into consideration the spatial distribution of the WGM at the surface of the resonator, thus being more accurate than the currently used expressions. It also takes into account the geometry of the prism. It is shown an improvement in the geometry values used with the current expressions of about 30%. The reason why the pump laser signal can be seen in experiments under critical coupling is explained on this basis. Then, the conditions required for exciting the highest possible optical power inside the resonator are obtained. The aim is to achieve a highly-efficient up-conversion of a THz signal into the optical domain via the second-order nonlinearity of the resonator material.

  1. Raman gain induced mode evolution and on-demand coupling control in whispering-gallery-mode microcavities.

    Science.gov (United States)

    Yang, Xu; Özdemir, Şahin Kaya; Peng, Bo; Yilmaz, Huzeyfe; Lei, Fu-Chuan; Long, Gui-Lu; Yang, Lan

    2015-11-16

    Waveguide-coupled optical resonators have played an important role in a wide range of applications including optical communication, sensing, nonlinear optics, slow/fast light, and cavity QED. In such a system, the coupling regimes strongly affect the resonance feature in the light transmission spectra, and hence the performance and outcomes of the applications. Therefore it is crucial to control the coupling between the waveguide and the microresonator. In this work, we investigated a fiber-taper coupled whispering-gallery-mode microresonator system, in which the coupling regime is traditionally controlled by adjusting the distance between the resonator and the fiber-taper mechanically. We propose and experimentally demonstrate that by utilizing Raman gain one can achieve on-demand control of the coupling regime without any mechanical movement in the resonator system. Particularly, the application of Raman gain is accompanied by Q enhancement. We also show that with the help of Raman gain control, the transitions between various coupling regimes can affect the light transmission spectra so as to provide better resolvability and signal amplification. This all-optical approach is also suitable for monolithically integrated and packaged waveguide-resonator systems, whose coupling regime is fixed at the time of manufacturing. It provides an effective route to control the light transmission in a waveguide-couple resonator system without mechanically moving individual optical components.

  2. Optical multistability and Fano line-shape control via mode coupling in whispering-gallery-mode microresonator optomechanics.

    Science.gov (United States)

    Zhang, Suzhen; Li, Jiahua; Yu, Rong; Wang, Wei; Wu, Ying

    2017-01-03

    We study a three-mode (i.e., a clockwise mode, a counterclockwise mode, and a mechanical mode) coherent coupling regime of the optical whispering-gallery-mode (WGM) microresonator optomechanical system by considering a pair of counterpropagating modes in a general case. The WGM microresonator is coherently driven by a strong control laser field and a relatively weak probe laser field via a tapered fiber. The system parameters utilized to explore this process correspond to experimentally demonstrated values in the WGM microresonator optomechanical systems. By properly adjusting the coupling rate of these two counterpropagating modes in the WGM microresonator, the steady-state displacement behaviors of the mechanical oscillation and the normalized power transmission and reflection spectra of the output fields are analyzed in detail. It is found that the mode coupling plays a crucial role in rich line-shape structures. Some interesting phenomena of the system, including optical multistability and sharp asymmetric Fano-shape optomechanically induced transparency (OMIT), can be generated with a large degree of control and tunability. Our obtained results in this study can be used for designing efficient all-optical switching and high-sensitivity sensor.

  3. Lasing mode regulation and single-mode realization in ZnO whispering gallery microcavities by the Vernier effect.

    Science.gov (United States)

    Wang, Y Y; Xu, C X; Jiang, M M; Li, J T; Dai, J; Lu, J F; Li, P L

    2016-10-07

    The wide direct bandgap and strong exciton binding energy of ZnO have inspired examinations of ultraviolet lasing over the previous decades. However, regulation of the lasing mode, especially the realization of single mode lasing, is still a challenge. In this study, a ZnO comb-like structure with an array of microrods was selected to design coupled whispering-gallery-mode cavities, wherein the naturally varied air-gap between the adjacent microrods created a flexible condition for optical field coupling without any complicated micromanipulation. Spectral behaviour of lasing and coupling interaction between coupled ZnO microrods were systematically investigated. By regulating the nano-scale inter-space of dual coupled microrods, stable single-mode lasing with a higher Q factor and lower threshold was obtained successfully based on the Vernier effect. The formation conditions and the mechanism of single-mode lasing derived from the coupled ZnO microrods were discussed in detail. It also demonstrated an approach to construct high quality single-mode lasing by tuning the diameters of the coupled ZnO microrods.

  4. Protein-Based Three-Dimensional Whispering-Gallery-Mode Micro-Lasers with Stimulus-Responsiveness.

    Science.gov (United States)

    Sun, Yun-Lu; Hou, Zhi-Shan; Sun, Si-Ming; Zheng, Bo-Yuan; Ku, Jin-Feng; Dong, Wen-Fei; Chen, Qi-Dai; Sun, Hong-Bo

    2015-08-04

    For the first time, proteins, a promising biocompatible and functionality-designable biomacromolecule material, acted as the host material to construct three-dimensional (3D) whispering-gallery-mode (WGM) microlasers by multiphoton femtosecond laser direct writing (FsLDW). Protein/Rhodamine B (RhB) composite biopolymer was used as optical gain medium innovatively. By adopting high-viscosity aqueous protein ink and optimized scanning mode, protein-based WGM microlasers were customized with exquisite true 3D geometry and smooth morphology. Comparable to previously reported artificial polymers, protein-based WGM microlasers here were endowed with valuable performances including steady operation in air and even in aqueous environments, and a higher quality value (Q) of several thousands (without annealing). Due to the "smart" feature of protein hydrogel, lasing spectrum was responsively adjusted by step of ~0.4 nm blueshift per 0.83-mmol/L Na2SO4 concentration change (0 ~ 5-mmol/L in total leading to ~2.59-nm blueshift). Importantly, other performances including Q, FWHM, FSR, peak intensities, exhibited good stability during adjustments. So, these protein-based 3D WGM microlasers might have potential in applications like optical biosensing and tunable "smart" biolasers, useful in novel photonic biosystems and bioengineering.

  5. Mathematical Model for Electric Field Sensor Based on Whispering Gallery Modes Using Navier’s Equation for Linear Elasticity

    Directory of Open Access Journals (Sweden)

    Amir R. Ali

    2017-01-01

    Full Text Available This paper presents and verifies the mathematical model of an electric field senor based on the whispering gallery mode (WGM. The sensing element is a dielectric microsphere, where the light is used to tune the optical modes of the microsphere. The light undergoes total internal reflection along the circumference of the sphere; then it experiences optical resonance. The WGM are monitored as sharp dips on the transmission spectrum. These modes are very sensitive to morphology changes of the sphere, such that, for every minute change in the sphere’s morphology, a shift in the transmission spectrum will happen and that is known as WGM shifts. Due to the electrostriction effect, the applied electric field will induce forces acting on the surface of the dielectric sphere. In turn, these forces will deform the sphere causing shifts in its WGM spectrum. The applied electric field can be obtained by calculating these shifts. Navier’s equation for linear elasticity is used to model the deformation of the sphere to find the WGM shift. The finite element numerical studies are performed to verify the introduced model and to study the behavior of the sensor at different values of microspheres’ Young’s modulus and dielectric constant. Furthermore, the sensitivity and resolution of the developed WGM electric filed sensor model will be presented in this paper.

  6. Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population

    Directory of Open Access Journals (Sweden)

    Boissinot K

    2010-01-01

    Full Text Available Abstract We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10−4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots.

  7. Whispering-gallery-mode based CH3NH3PbBr3 perovskite microrod lasers with high quality factors

    CERN Document Server

    Wang, Kaiyang; Zhang, Chen; Sun, Wenzhao; Gu, Zhiyuan; Xiao, Shumin; Song, Qinghai

    2016-01-01

    Lead halide perovskite based micro- and nano- lasers have been widely studied in past two years. Due to their long carrier diffusion length and high external quantum efficiency, lead halide perovskites have been considered to have bright future in optoelectronic devices, especially in the "green gap" wavelength region. However, the quality (Q) factors of perovskite lasers are unspectacular compared to conventional microdisk lasers. The record value of full width at half maximum (FWHM) at threshold is still around 0.22 nm. Herein we synthesized solution-processed, single-crystalline CH3NH3PbBr3 perovskite microrods and studied their lasing actions. In contrast to entirely pumping a microrod on substrate, we partially excited the microrods that were hanging in the air. Consequently, single-mode or few-mode laser emissions have been successfully obtained from the whispering-gallery like diamond modes, which are confined by total internal reflection within the transverse plane. Owning to the better light confinem...

  8. Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population

    Science.gov (United States)

    Charlebois, M.; Paquet, A.; Verret, L. S.; Boissinot, K.; Boissinot, M.; Bergeron, M. G.; Allen, C. Nì.

    2010-03-01

    We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs) without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10-4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots.

  9. Low-threshold whispering-gallery-mode microlasers fabricated in a Nd: glass substrate by three-dimensional femtosecond laser micromachining

    CERN Document Server

    Lin, Jintian; Song, Jiangxin; Zeng, Bin; He, Fei; Xu, Huailiang; Sugioka, Koji; Fang, Wei; Cheng, Ya

    2013-01-01

    We report on fabrication of whispering-gallery-mode microlasers in a Nd:glass chip by femtosecond laser three-dimensional (3D) micromachining. Main fabrication procedures include the fabrication of freestanding microdisks supported by thin pillars by femtosecond laser ablation of the glass substrate immersed in water, followed by CO2 laser annealing for surface smoothing. Lasing is observed at a pump threshold as low as ~69 {\\mu}W at room temperature with a continuous-wave laser diode operating at 780nm. This technique allows for fabrication of microcavities of high quality factors in various dielectric materials such as glasses and crystals.

  10. High quality factor whispering gallery modes from self-assembled hexagonal GaN rods grown by metal-organic vapor phase epitaxy.

    Science.gov (United States)

    Tessarek, C; Sarau, G; Kiometzis, M; Christiansen, S

    2013-02-11

    Self-assembled GaN rods were grown on sapphire by metal-organic vapor phase epitaxy using a simple two-step method that relies first on a nitridation step followed by GaN epitaxy. The mask-free rods formed without any additional catalyst. Most of the vertically aligned rods exhibit a regular hexagonal shape with sharp edges and smooth sidewall facets. Cathodo- and microphotoluminescence investigations were carried out on single GaN rods. Whispering gallery modes with quality factors greater than 4000 were measured demonstrating the high morphological and optical quality of the self-assembled GaN rods.

  11. Gyrotron whispering gallery mode coupler with a mode conversion reflector for exciting a circular symmetric uniform phase RF beam in a corrugated waveguide

    Science.gov (United States)

    Neilson, Jeffrey M.

    2017-07-25

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  12. Coupling Light from a High-Q Microsphere Resonator Using a UV-induced Surface Grating

    Science.gov (United States)

    Ilchenko, V. S.; Starodubov, D. S.; Gorodetsky, M. L.; Maleki, L.; Feinberg, J.

    2000-01-01

    High-Q microspheres with whispering-gallery modes have very narrow resonances that can be used for fiber-optic filters, ultra-compact narrow-linewidth lasers and optical/microwave oscillators. Whispering-gallery modes were previously excited in microspheres using evanescent optical fields. The necessary phase synchronism was obtained by adjusting the incident angle of input light beam (prism coupler) or adjustment of the waveguide propagation constant (fiber taper coupler). For many applications, however, bulky near-field couplers are undesirable. They compromise the symmetry and generate stray fields. Also, the control of coupling is crucial for the performance of microsphere resonators: in analogy with radio frequency circuits, the loading Q-factor should be less than the intrinsic Q-factor, Q(sub L) less than or equal to Q(sub O). Ideally one should combine a stable coupling element and a resonator into a single microsphere component.

  13. Lasing of whispering-gallery modes in asymmetric waveguide GaInP micro-disks with InP quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Y. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)], E-mail: ychu@nd.edu; Mintairov, A.M.; He, Y.; Merz, J.L. [Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Kalyuzhnyy, N.A.; Lantratov, V.M.; Mintairov, S.A. [Ioffe Physical Technical Institute, St. Petersburg (Russian Federation)

    2009-03-16

    Using wafer bonding (WB) and wet oxidation (WO) techniques, GaInP microdisks having an asymmetric waveguide (diameters D=1-3 {mu}m) with embedded InP quantum dots (size/density {approx}100 nm/{approx}10{sup 9} cm{sup -2}) have been fabricated on Si and GaAs substrates, respectively. The TE{sub m,l} (m=28-12, l=1,2) and TM{sub m,l} (m=25-10, l=1-4) whispering gallery modes with quality factors Q{approx}2-5x10{sup 3} have been identified in photoluminescence spectra of these microdisks (MDs) in the spectral range 720-770 nm. Lasing thresholds of 6 (30) {mu}W and mode coupling constants 0.9 (0.7) have been demonstrated for WO (WB) MDs.

  14. Whispering gallery mode in periodic InGaN-based hexagonal nanoring arrays grown by rf-MBE using Ti-mask selective-area growth

    Energy Technology Data Exchange (ETDEWEB)

    Kouno, Tetsuya [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); CREST, Japan Science and Technology Agency, Tokyo (Japan); Kishino, Katsumi; Kikuchi, Akihiko [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Sophia Nanotechnology Research Center, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); CREST, Japan Science and Technology Agency, Tokyo (Japan)

    2010-01-15

    We fabricated periodic InGaN-based hexagonal nanoring arrays by rf-molecular beam epitaxy (rf-MBE) with Ti-mask selective-area growth (SAG). Multiple photoluminescence peaks from InGaN-based hexagonal nanorings were observed in room temperature photoluminescence (RT-PL) measurements with a 325 nm He-Cd laser. We employed a simple plane wave model and a two-dimensional finite difference time domain (2D-FDTD) method in the numerical analysis to investigate these multiple peaks. Experimental data was in good coincidence with calculated data, evincing that whispering gallery modes (WGMs) supported in the InGaN-based hexagonal nanorings were responsible for the multipeaks. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range

    CERN Document Server

    Lin, Guoping

    2015-01-01

    Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above $10^9$. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion ($GVD$). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the $GVD$ of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar $GVD$, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to pus...

  16. Classification of the micro and nanoparticles and biological agents by neural network analysis of the parameters of optical resonance of whispering gallery mode in dielectric microspheres

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav; Ostendorf, Andreas

    2011-07-01

    A novel technique for the label-free analysis of micro and nanoparticles including biomolecules using optical micro cavity resonance of whispering-gallery-type modes is being developed. Various schemes of the method using both standard and specially produced microspheres have been investigated to make further development for microbial application. It was demonstrated that optical resonance under optimal geometry could be detected under the laser power of less 1 microwatt. The sensitivity of developed schemes has been tested by monitoring the spectral shift of the whispering gallery modes. Water solutions of ethanol, ascorbic acid, blood phantoms including albumin and HCl, glucose, biotin, biomarker like C reactive protein so as bacteria and virus phantoms (gels of silica micro and nanoparticles) have been used. Structure of resonance spectra of the solutions was a specific subject of investigation. Probabilistic neural network classifier for biological agents and micro/nano particles classification has been developed. Several parameters of resonance spectra as spectral shift, broadening, diffuseness and others have been used as input parameters to develop a network classifier for micro and nanoparticles and biological agents in solution. Classification probability of approximately 98% for probes under investigation have been achieved. Developed approach have been demonstrated to be a promising technology platform for sensitive, lab-on-chip type sensor which can be used for development of diagnostic tools for different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells as well as in different experimental contexts e.g. proteomics, genomics, drug discovery, and membrane studies.

  17. InAsSb/InAsPSb multiple quantum well disk cavities with pedestal structures on a GaSb substrate for mid-infrared whispering-gallery-mode emission beyond 4  μm.

    Science.gov (United States)

    Lin, Yen-Chih; Mao, Ming-Hua; Wu, Chen-Jun; Lin, Hao-Hsiung

    2015-05-01

    The mid-infrared whispering-gallery-mode disk cavities with InAs0.85Sb0.15/InAs0.53P0.23Sb0.24 multiple quantum wells active medium on a GaSb substrate were fabricated. For this material system in the mid-infrared range, fabrication techniques were developed to form the disk cavity structure. The smooth sidewalls of the disk cavities were achieved by appropriate gas mixture flow ratio of BCl3/Ar in the inductively coupled plasma-reactive ion etching. In addition, selective wet etching technique was used to form the pedestal of the disk cavity using dilute hydrofluoric acid with good selectivity. For efficient confinement of the whispering gallery modes along the radial direction, the extent of the lateral etching was carefully controlled. The processed 30-μm-diameter disk cavities were optically pumped, and the whispering gallery modes with wavelengths around 4.1 μm can be observed up to 90 K.

  18. Implementation of single-photon quantum routing and decoupling using a nitrogen-vacancy center and a whispering-gallery-mode resonator-waveguide system.

    Science.gov (United States)

    Cao, Cong; Duan, Yu-Wen; Chen, Xi; Zhang, Ru; Wang, Tie-Jun; Wang, Chuan

    2017-07-24

    Quantum router is a key element needed for the construction of future complex quantum networks. However, quantum routing with photons, and its inverse, quantum decoupling, are difficult to implement as photons do not interact, or interact very weakly in nonlinear media. In this paper, we investigate the possibility of implementing photonic quantum routing based on effects in cavity quantum electrodynamics, and present a scheme for single-photon quantum routing controlled by the other photon using a hybrid system consisting of a single nitrogen-vacancy (NV) center coupled with a whispering-gallery-mode resonator-waveguide structure. Different from the cases in which classical information is used to control the path of quantum signals, both the control and signal photons are quantum in our implementation. Compared with the probabilistic quantum routing protocols based on linear optics, our scheme is deterministic and also scalable to multiple photons. We also present a scheme for single-photon quantum decoupling from an initial state with polarization and spatial-mode encoding, which can implement an inverse operation to the quantum routing. We discuss the feasibility of our schemes by considering current or near-future techniques, and show that both the schemes can operate effectively in the bad-cavity regime. We believe that the schemes could be key building blocks for future complex quantum networks and large-scale quantum information processing.

  19. On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range.

    Science.gov (United States)

    Lin, Guoping; Chembo, Yanne K

    2015-01-26

    Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above 109. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion (GVD). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the GVD of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar GVD, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to push the zero-dispersion wavelength of fluorite crystals towards the mid-infrared (mid-IR) range, thereby allowing for efficient Kerr comb generation in that spectral range. We show that barium fluoride is the most interesting crystal in this regard, due to its zero dispersion wavelength (ZDW) at 1.93 μm and an optimal dispersion profile in the mid-IR regime. We expect our results to facilitate the design of different platforms for Kerr frequency comb generations in both telecommunication and mid-IR spectral ranges.

  20. Engineering the Absorption and Field Enhancement Properties of Au-TiO2 Nanohybrids via Whispering Gallery Mode Resonances for Photocatalytic Water Splitting.

    Science.gov (United States)

    Zhang, Jianming; Jin, Xin; Morales-Guzman, Pablo I; Yu, Xin; Liu, Hong; Zhang, Hua; Razzari, Luca; Claverie, Jerome P

    2016-04-26

    Recently, surface plasmon resonance (SPR) effects have been widely used to construct photocatalysts which are active in the visible spectral region. Such plasmonic photocatalysts usually comprise a semiconductor material transparent in the visible range (such as TiO2) and plasmonic nano-objects (e.g., Au nanoparticles (Au NPs)). Specific SPRs, though, only partially cover the visible spectrum and feature weak light absorption. Here, we explore the unique role played by whispering gallery mode (WGM) resonances in the expression of the photocatalytic activity of plasmonic photocatalysts. Using numerical simulations, we demonstrate that, by solely exploiting a proper geometrical arrangement and WGM resonances in a TiO2 sphere, the plasmonic absorption can be extended over the entire visible range and can be increased by more than 40 times. Furthermore, the local electric field at the Au-TiO2 interface is also considerably enhanced. These results are experimentally corroborated, by means of absorption spectroscopy and Raman measurements. Accordingly, such WGM-assisted plasmonic photocatalysts, when employed in water splitting experiments, exhibit enhanced activity in the visible range. Our findings show a promising and straightforward way to design full solar spectrum photocatalysts.

  1. Analytical and simulation results of a triple micro whispering gallery mode probe system for a 3D blood flow rate sensor.

    Science.gov (United States)

    Phatharacorn, Prateep; Chiangga, Surasak; Yupapin, Preecha

    2016-11-20

    The whispering gallery mode (WGM) is generated by light propagating within a nonlinear micro-ring resonator, which is modeled and made by an InGaAsP/InP material, and called a Panda ring resonator. An imaging probe can also be formed by the micro-conjugate mirror function for the appropriate Panda ring parameter control. The 3D WGM probe can be generated and used for a 3D sensor head and imaging probe. The analytical details and simulation results are given, in which the simulation results are obtained by using the MATLAB and Optiwave programs. From the obtained results, such a design system can be configured to be a thin-film sensor system that can contact the sample surface for the required measurements The outputs of the system are in the form of a WGM beam, in which the 3D WGM probe is also available with the micro-conjugate mirror function. Such a 3D probe can penetrate into the blood vessel and content, from which the time delay among those probes can be detected and measured, and where finally the blood flow rate can be calculated and the blood content 3D image can also be seen and used for medical diagnosis. The tested results have shown that the blood flow rate of 0.72-1.11  μs-1, with the blood density of 1060  kgm-3, can be obtained.

  2. Ultra-sensitive optical biosensor based on whispering gallery modes: The effect of buffer solutions refractive index on their sensitivity and performance

    Science.gov (United States)

    Nadgaran, Hamid; Pourmand, Raheleh

    2013-01-01

    Background: Whispering gallery modes (WGM) biosensors are ultrasensitive systems that can measure amount of adsorbed layer onto the micro-cavity surface. They have many applications including protein, peptide growth, DNA and bacteria detection, molecular properties measurements and specific interaction and drug table recognitions due to their high sensitivity, compact size and label free sensing mechanism.     Objective: In this paper we investigate the effect of buffer solution on detection of specific biomolecules in WGM biosensors through its refractive index change. Methods: The propagation of electromagnetic waves in a dielectric microsphere is analyzed by solving Maxwell’s equations through proper boundary condition to find a concise relation for micro-cavity resonance shift. Results: Analysis of the buffer solution’s refractive index effects on detection of BSA by WGM biosensors are presented and it was shown that even a very small change in the refractive index of buffer solution can affect the biosensor wavelength shift and the sensitivity of biosensors. Conclusion: This study opens up a discussion in biosensor sensitivity based on true and reliable performance of the buffer solution through its accurate determination of refractive index and behavior. To avoid expensive methods of enhancing sensitivity, one can improve the sensitivity of WGM biosensor to some extent, by means of using proper buffer solution. PMID:25505748

  3. Construction of high-dimensional universal quantum logic gates using a Λ system coupled with a whispering-gallery-mode microresonator.

    Science.gov (United States)

    He, Ling Yan; Wang, Tie-Jun; Wang, Chuan

    2016-07-11

    High-dimensional quantum system provides a higher capacity of quantum channel, which exhibits potential applications in quantum information processing. However, high-dimensional universal quantum logic gates is difficult to achieve directly with only high-dimensional interaction between two quantum systems and requires a large number of two-dimensional gates to build even a small high-dimensional quantum circuits. In this paper, we propose a scheme to implement a general controlled-flip (CF) gate where the high-dimensional single photon serve as the target qudit and stationary qubits work as the control logic qudit, by employing a three-level Λ-type system coupled with a whispering-gallery-mode microresonator. In our scheme, the required number of interaction times between the photon and solid state system reduce greatly compared with the traditional method which decomposes the high-dimensional Hilbert space into 2-dimensional quantum space, and it is on a shorter temporal scale for the experimental realization. Moreover, we discuss the performance and feasibility of our hybrid CF gate, concluding that it can be easily extended to a 2n-dimensional case and it is feasible with current technology.

  4. Single step integration of ZnO nano- and microneedles in Si trenches by novel flame transport approach: whispering gallery modes and photocatalytic properties.

    Science.gov (United States)

    Reimer, Tim; Paulowicz, Ingo; Röder, Robert; Kaps, Sören; Lupan, Oleg; Chemnitz, Steffen; Benecke, Wolfgang; Ronning, Carsten; Adelung, Rainer; Mishra, Yogendra K

    2014-05-28

    Direct growth of quasi-one-dimensional nano- and microstructures in desired places of complex shaped substrates using simple growth methods is highly demanded aspect for various applications. In this work, we have demonstrated direct integration of ZnO nano- and microneedles into Si trenches by a novel flame transport synthesis approach in a single fabrication step. Growth of partially and fully covered or filled trenches in Si substrate with ZnO nano- and microneedles has been investigated and is discussed here. Detailed microstructural studies revealed the evolution of the ZnO nano- and microneedles as well as their firm adhesion to the wall in the Si trenches. Micro-photoluminescence measurements at different locations along the length of needles confirmed the good crystalline quality and also the presence of whispering gallery mode resonances on the top of needles due to their hexagonal shape. Faceted ZnO nano- and microstructures are also very important candidates with regard to photocatalytic activity. First, photocatalytic measurements from the grown ZnO nano- and microneedles have shown strong degradation of methylene blue, which demonstrate that these structures can be of significant interest for photocatalysis and self-cleaning chromatography columns.

  5. Discovery of iron group impurity ion spin states in single crystal Y{sub 2}SiO{sub 5} with strong coupling to whispering gallery photons

    Energy Technology Data Exchange (ETDEWEB)

    Goryachev, Maxim; Farr, Warrick G.; Carmo Carvalho, Natalia do; Creedon, Daniel L.; Le Floch, Jean-Michel [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Probst, Sebastian [Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe (Germany); Bushev, Pavel [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany); Tobar, Michael E., E-mail: michael.tobar@uwa.edu.au [ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, University of Western Australia, Crawley 6009 (Australia)

    2015-06-08

    Interaction of Whispering Gallery Modes (WGMs) with dilute spin ensembles in solids is an interesting paradigm of Hybrid Quantum Systems potentially beneficial for Quantum Signal Processing applications. Unexpected ion transitions are measured in single crystal Y{sub 2}SiO{sub 5} using WGM spectroscopy with large Zero Field Splittings at 14.7 GHz, 18.4 GHz, and 25.4 GHz, which also feature considerable anisotropy of the g-tensors as well as two inequivalent lattice sites, indicating spins from Iron Group Ion (IGI) impurities. The comparison of undoped and Rare-Earth doped crystals reveal that the IGIs are introduced during co-doping of Eu{sup 3+} or Er{sup 3+} with concentration at much lower levels of order 100 ppb. The strong coupling regime between an ensemble of IGI spins and WGM photons have been demonstrated at 18.4 GHz and near zero field. This approach together with useful optical properties of these ions opens avenues for “spins-in-solids” Quantum Electrodynamics.

  6. PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing

    Directory of Open Access Journals (Sweden)

    Fanyongjing Wang

    2015-07-01

    Full Text Available Whispering Gallery Mode (WGM optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol (PEG can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor’s performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection.

  7. PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing.

    Science.gov (United States)

    Wang, Fanyongjing; Anderson, Mark; Bernards, Matthew T; Hunt, Heather K

    2015-07-24

    Whispering Gallery Mode (WGM) optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol) (PEG) can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor's performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection.

  8. Low-threshold Raman laser from an on-chip, high-Q, polymer-coated microcavity.

    Science.gov (United States)

    Li, Bei-Bei; Xiao, Yun-Feng; Yan, Meng-Yuan; Clements, William R; Gong, Qihuang

    2013-06-01

    We study the stimulated Raman emission of a high-Q polydimethylsiloxane (PDMS)-coated silica microsphere on a silicon chip. In this hybrid structure, as the thickness of the PDMS coating increases, the spatial distribution of the whispering gallery modes moves inside the PDMS layer, and the light emission switches from silica Raman lasing to PDMS Raman lasing. The Raman shift of the PDMS Raman laser is measured at 2900 cm(-1), corresponding to the strongest Raman fingerprint of bulk PDMS material. The threshold for this PDMS Raman lasing is demonstrated to be as low as 1.3 mW. This type of Raman emission from a surface-coated high-Q microcavity not only provides a route for extending lasing wavelengths, but also shows potential for detecting specific analytes.

  9. High Q-factor micro-cavity laser: Fabrication and lasing emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Pham Van Hoi; Ha Xuan Vinh; Chu Thi Thu Ha; Tran Thi Cham [Institute of Materials Science, Vietname Academy of Science and Technology 18 Hoang Quoc Viet Road, Cau Giay District, Hanoi (Viet Nam); Bui Van Thien [Faculty of Natural Science, College of Medicine, Thai Nguyen (Viet Nam); Gruzintsev, A N [Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences (IPMT-RAS) (Russian Federation)], E-mail: hoipv@ims.vast.ac.vn

    2009-09-01

    In this article the fabrication method and lasing emission properties of High-Q micro-cavity lasers based on High-concentration Erbium-doped silica-alumina glasses are presented in detail. The configurations of micro-cavities were spherical and/or modified toroidal forms. The lasing threshold of micro-cavity laser pumped by laser diodes was of hundred micro-watts and Q-factor of cavity had been achieved up-to 10{sup 8} in experiment. The emission power of one whispering-gallery-mode (WGM) lasing from micro-cavity laser was of 0.05-0.5 mW that would be enough for applying in the quantum information and optical sensor techniques. The modified toroidal micro-cavity permits to decrease the polar-mode of WGMs, which help to obtain the single-mode emission from micro-cavity lasers.

  10. Nonlinear properties of high-Q optical microresonators in normal dispersion range

    Directory of Open Access Journals (Sweden)

    Shitikov Artem

    2017-01-01

    Full Text Available We demonstrate the generation of Kerr frequency combs and platicons in whispering gallery mode crystalline microresonators in normal group velocity regime at 780 nm and 1064 nm wavelengths.

  11. Understanding GaN/InGaN core–shell growth towards high quality factor whispering gallery modes from non-polar InGaN quantum wells on GaN rods

    Science.gov (United States)

    Tessarek, C.; Rechberger, S.; Dieker, C.; Heilmann, M.; Spiecker, E.; Christiansen, S.

    2017-12-01

    GaN microrods are used as a basis for subsequent InGaN quantum well (QW) and quantum dot deposition by metal-organic vapor phase epitaxy. The coverage of the shell along the sidewall of rods is dependent on the rod growth time and a complete coverage is obtained for shorter rod growth times. Transmission electron microscopy measurements are performed to reveal the structural properties of the InGaN layer on the sidewall facet and on the top facet. The presence of layers in the microrod and on the microrod surface will be discussed with respect to GaN and InGaN growth. A detailed model will be presented explaining the formation of multiple SiN layers and the partial and full coverage of the shell around the core. Cathodoluminescence measurements are performed to analyze the InGaN emission properties along the microrod and to study the microresonator properties of such hexagonal core–shell structures. High quality factor whispering gallery modes with Q∼ 1200 are reported for the first time in a GaN microrod/InGaN non-polar QW core–shell geometry. The GaN/InGaN core–shell microrods are expected to be promising building blocks for low-threshold laser diodes and ultra-sensitive optical sensors.

  12. Mid-Infrared ultra-high-Q resonators based on fluoride crystalline materials

    CERN Document Server

    Lecaplain, C; Gorodetsky, M L; Kippenberg, T J

    2016-01-01

    Decades ago, the losses of glasses in the near infrared (near-IR) were investigated in views of developments for optical telecommunications. Today, properties in the mid-infrared (mid-IR) are of interest for molecular spectroscopy applications. In particular, high-sensitivity spectroscopic techniques based on high-finesse mid-IR cavities hold high promise for medical applications. Due to exceptional purity and low losses, whispering gallery mode microresonators based on polished alkaline earth metal fluoride crystals (i.e the $\\mathrm{XF_2}$ family, where X $=$ Ca, Mg, Ba, Sr,...) have attained ultra-high quality (Q) factor resonances (Q$>$10$^{8}$) in the near-IR and visible spectral ranges. Here we report for the first time ultra-high Q factors in the mid-IR using crystalline microresonators. Using an uncoated chalcogenide (ChG) tapered fiber, light from a continuous wave quantum cascade laser (QCL) is efficiently coupled to several crystalline microresonators at 4.4 $\\mu$m wavelength. We measure the optica...

  13. Thermal Properties of Whispering Gallery Mode Resonators

    Science.gov (United States)

    2014-12-22

    unique fabrication process which involves melting and reflowing glass material that produces extremely smooth surfaces. They also have very small...has a strong absorption at 10 µm wavelength. The beam from the CO2 laser was first expanded by a ZnSe lens and then passed through a small pinhole ...Only a small fraction of total IR radiation passes through the pinhole and reaches at the resonator. The microtoroid was placed at an angle of 45

  14. Fundamental limits in high-Q droplet microresonators

    Science.gov (United States)

    Giorgini, A.; Avino, S.; Malara, P.; de Natale, P.; Gagliardi, G.

    2017-02-01

    Liquid droplet whispering-gallery-mode microresonators open a new research frontier for sensing, optomechanics and photonic devices. At visible wavelengths, where most liquids are transparent, a major contribution to a droplet optical quality factor is expected theoretically from thermal surface distortions and capillary waves. Here, we investigate experimentally these predictions using transient cavity ring-down spectroscopy. With our scheme, the optical out-coupling and intrinsic loss are measured independently while any perturbation induced by thermal, acoustic and laser-frequency noise is avoided thanks to the ultra-short light-cavity interaction time. The measurements reveal a photon lifetime at least ten times longer than the thermal limit and indicate that capillary fluctuations activate surface scattering effects responsible for light coupling. This suggests that droplet microresonators are an ideal optical platform for ultra-sensitive spectroscopy of highly transparent liquid compounds in nano-liter volumes.

  15. Frequency-Temperature Compensation Techniques for High-Q Microwave Resonators

    Science.gov (United States)

    Hartnett, John G.; Tobar, Michael E.

    Low-noise high-stability resonator oscillators based on high-Q monolithic sapphire ``Whispering Gallery'' (WG)-mode resonators have become important devices for telecommunication, radar and metrological applications. The extremely high quality factor of sapphire, of 2 x10^5 at room temperature, 5 x10^7 at liquid nitrogen temperature and 5 x10^9 at liquid helium temperature has enabled the lowest phase noise and highly frequency-stable oscillators in the microwave regime to be constructed. To create an oscillator with exceptional frequency stability, the resonator must have its frequency-temperature dependence annulled at some temperature, as well as a high quality factor. The Temperature Coefficient of Permittivity (TCP) for sapphire is quite large, at 10-100parts per million/K above 77K. This mechanism allows temperature fluctuations to transform to resonator frequency fluctuations.A number of research groups worldwide have investigated various methods of compensating the TCP of a sapphire dielectric resonator at different temperatures. The usual electromagnetic technique of annulment involves the use of paramagnetic impurities contributing an opposite temperature coefficient of the magnetic susceptibility to the TCP. This technique has only been realized successfully in liquid helium environments. Near 4K the thermal expansion and permittivity effects are small and only small quantities of the paramagnetic ions are necessary to compensate the mode frequency. Compensation is due to impurity ions that were incidentally left over from the manufacturing process.Recently, there has been an effort to dispense with the need for liquid helium and make a compact flywheel oscillator for the new generation of primary frequency standards such as the cesium fountain at the Laboratoire Primaire du Temps et des Fréquences (LPTF), France. To achieve the stability limit imposed by quantum projection noise requires that the local oscillator stability is of the order of 10

  16. Group Delay of High Q Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert Frølund

    2013-01-01

    become an issue, when working with high Q antennas, because of the steep phase shift over the frequency. In this paper, it is measured how large group delay variations can become, when going from a low Q antenna to a high Q antenna. The group delay of a low Q antenna is shown to be around 1.3 ns, whereas...... a high Q antenna has group delay of around 22 ns. It is due to this huge group delay variation characteristics of high Q antennas, that signal distortion might occur in the radio system with high Q antennas....

  17. Waveguide couplers for ferroelectric optical resonators

    OpenAIRE

    Grudinin, Ivan S.; Kozhanov, A.; Yu, N.

    2014-01-01

    We report a study of using the same material to fabricate a whispering gallery mode resonator and a coupler. Coupling to high Q whispering gallery modes of the lithium niobate resonator is demonstrated by means of the titanium-doped waveguide. The waveguide coupling approach opens possibilities for simpler and wider practical usage of whispering gallery mode resonators and their integration into optical devices.

  18. VLF/LF/MF Whispering Gallery Propagation Studies.

    Science.gov (United States)

    1981-09-09

    can be expressed as ry0 HGF = AnGn (z)Gn(z) - tn)1/2ki(tn - z)Ai(t - ). (8)n n n ~ 2 (Yo 0 ~ If both the transmitting and receiving antennas are...6503 10 PR 1/2 [n ~D v- h [a sin D/aJ AnGn (Z)Gn(;) exp 1--61 V/m, (9) n where all lengths are in meters and the radiated power, PR’ is in kilowatts...P.Greifinger) 2 Pacific-Sierra Research Corp., 1456 Cloverfield Boulevard, Santa Monica , CA 90404 (E. C. Field) I Johns Hopkins University, Applied Physics

  19. Ultrahigh-Q Tunable Whispering-Gallery-Mode Microresonator

    NARCIS (Netherlands)

    Poellinger, M.; O'Shea, D.; Warken, F.; Rauschenbeutel, A.

    2009-01-01

    Typical microresonators exhibit a large frequency spacing between resonances and a limited tunability. This impedes their use in a large class of applications which require a resonance of the microresonator to coincide with a predetermined frequency. Here, we experimentally overcome this limitation

  20. Lithium-Niobate-Silica Hybrid Whispering-Gallery-Mode Resonators.

    Science.gov (United States)

    Bo, Fang; Wang, Jie; Cui, Jiao; Ozdemir, Sahin Kaya; Kong, Yongfa; Zhang, Guoquan; Xu, Jingjun; Yang, Lan

    2015-12-22

    Lithium-niobate-silica hybrid resonators with quality factors higher than 10(5) are fabricated by depositing a layer of polycrystalline lithium niobate on the flat top surfaces of inverted-wedge silica microdisk resonators. All-optical modulation with improved performance over silica-only resonators and electro-optic modulation not achievable in silica-only resonators are realized in the hybrid resonators. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Parity-Time-Symmetric Whispering-Gallery Microcavities

    Science.gov (United States)

    2014-04-06

    Nature Photon. 4, 46–49 (2010). 48. Dantham, V. R. et al. Label-free detection of single protein using a nanoplasmonic-photonic hybrid microcavity. Nano ...microcavities. μR1: active microtoroid; μR2: passive microtoroid; PD: photodetector; WDM: wavelength division multiplexer; FC: fiber connector; TEC ...resonators and fiber tapers as well as between the directly-coupled active and passive resonators. 5) Thermoelectric cooler ( TEC ) used to tune

  2. Quantum Light from a Whispering-Gallery-Mode Disk Resonator

    DEFF Research Database (Denmark)

    Fürst, J. U.; Strekalov, D. V.; Elser, D.

    2011-01-01

    Optical parametric down-conversion has proven to be a valuable source of nonclassical light. The process is inherently able to produce twin-beam correlations along with individual intensity squeezing of either parametric beam, when pumped far above threshold. Here, we present for the first time t...

  3. On-chip sensing with high-Q amorphous silicon microdisk resonators

    Science.gov (United States)

    Lipka, T.; Amthor, J.; Müller, J.

    2013-05-01

    In this paper we present a low-loss hydrogenated amorphous silicon microdisk resonator which is employed for evanescent field refractive index sensing. The resonances of the whispering gallery modes have extinction ratios of measurements the resonators intrinsic limit of detection was calculated to be LOD=3.3x10-4 and the minimum detectable amount of NaCl diluted in DI-water was determined to be 0.0375%. The early results prove that photonic microdisk resonators that are fabricated with low-loss hydrogenated amorphous silicon material can be applied in a variety of different areas for label-free lab-on-chip sensing, including chemical, medical and bio-sensing applications.

  4. Integrated Ultra-High-Q Optical Resonator

    OpenAIRE

    Yang, Ki Youl; Oh, Dong Yoon; Lee, Seung Hoon; Yang, Qi-Fan; Yi, Xu; Vahala, Kerry

    2017-01-01

    Optical microcavities are compact, often chip-based devices, that are essential in technologies spanning frequency metrology to biosensing. They have also enabled new science in quantum information and cavity optomechanics. Performance requirements in subjects like cavity-QED and sensing have long placed emphasis on low-optical-loss (high-Q-factor) micrometer-scale resonators. However, an array of system-on-a-chip applications have emerged that also require millimeter-scale devices. To avoid ...

  5. Reconstruction of speech from whispers.

    Science.gov (United States)

    Morris, Robert W; Clements, Mark A

    2002-01-01

    This paper investigates a method for the real-time reconstruction of normal speech from whispers. This system could be used by aphonic individuals as a voice prosthesis. It could also provide improved verbal communication when normal speech is not appropriate. The normal speech is synthesized using the mixed excitation linear prediction model. Differences between whispered and phonated speech are discussed and methods for estimating the parameters of this model from whispered speech for real-time synthesis are proposed. This includes smoothing the noisy linear prediction spectra, modifying the formants, and synthesizing of the excitation signal. Trade-offs between computational complexity, delay, and accuracy of different methods are discussed.

  6. NAIP Status Maps Gallery

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — NAIP Status Maps Gallery. These maps illustrate what aerial imagery collection is planned, whats been collected, when it is available and how it is available. These...

  7. Lunar Orbiter Photo Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...

  8. A comprehensive vowel space for whispered speech.

    Science.gov (United States)

    Sharifzadeh, Hamid Reza; McLoughlin, Ian V; Russell, Martin J

    2012-03-01

    Whispered speech is a relatively common form of communications, used primarily to selectively exclude or include potential listeners from hearing a spoken message. Despite the everyday nature of whispering, and its undoubted usefulness in vocal communications, whispers have received relatively little research effort to date, apart from some studies analyzing the main whispered vowels and some quite general estimations of whispered speech characteristics. In particular, a classic vowel space determination has been lacking for whispers. For voiced speech, this type of information has played an important role in the development and testing of recognition and processing theories over the past few decades and can be expected to be equally useful for whisper-mode communications and recognition systems. This article aims to redress the shortfall by presenting a vowel formant space for whispered speech and comparing the results with corresponding phonated samples. In addition, because the study was conducted using speakers from Birmingham, the analysis extends to discuss the effect of the common British West Midlands accent in comparison with Standard English (Received Pronunciation). Thus, the article presents the analysis of formant data showing differences between normal and whispered speech while also considering an accentual effect on whispered speech. Copyright © 2012 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  9. Detuning effect study of High-Q Mobile Phone Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert F.

    2015-01-01

    Number of frequency bands that have to be covered by smart phones, are ever increasing. This broadband coverage can be obtained either by using a low-Q antenna or a high-Q tunable antenna. This study investigates high-Q antennas performance when placed in proximity of the user. This study...

  10. Covariance Data File Formats for Whisper-1.0 & Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-09

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation. It uses the sensitivity profile data for an application as computed by MCNP6 along with covariance files for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014. During 2015-2016, Whisper was updated to version 1.1 and is to be included with the upcoming release of MCNP6.2. This report describes the file formats used for the covariance data in both Whisper-1.0 and Whisper-1.1.

  11. User Manual for Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-26

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation [1-3]. It uses the sensitivity profile data for an application as computed by MCNP6 [4-6] along with covariance files [7,8] for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014 [3]. During 2015- 2016, Whisper was updated to version 1.1 and is to be included with the upcoming release of MCNP6.2. This document describes the user input and options for running whisper-1.1, including 2 perl utility scripts that simplify ordinary NCS work, whisper_mcnp.pl and whisper_usl.pl. For many detailed references on the theory, applications, nuclear data & covariances, SQA, verification-validation, adjointbased methods for sensitivity-uncertainty analysis, and more – see the Whisper – NCS Validation section of the MCNP Reference Collection at mcnp.lanl.gov. There are currently over 50 Whisper reference documents available.

  12. [Glottal and supraglottal configuration during whispering].

    Science.gov (United States)

    Fleischer, S; Kothe, C; Hess, M

    2007-04-01

    The purpose of the study was to assess glottal and supraglottal configurations during whispering in comparison to habitual phonation and to visually estimate to what extent force is exerted onto the vocal fold epithelium during whispering. Is whispering a good compromise between preservation of epithelium and permission to communicate orally, e. g. postoperatively? We investigated on 100 patients with organic or non-organic voice disorders. Patients with vocal fold immobility and patients with organic lesions large enough to impede glottal closure were excluded. Videolaryngoscopy and stroboscopy was performed via flexible endoscopy. During fiberoscopy the patients were asked (i) to phonate and then whisper a series of vowels in various loudness levels and (ii) to count to 10 voiced and whispered in various loudness levels. The extent of vocal fold adduction and supraglottal configuration were assessed and whispering compared with voiced phonation. Interindividual differences in glottal and supraglottal configuration during whispering were seen. The two different and most frequently seen glottal area patterns were determined by the position of the vocal processes - either adducted or abducted. Adduction resulted in sole cartilaginous triangle formation or 'kissing processes', abduction in ligamentous and cartilaginous triangle. Another surprising result was that with increasing loudness either a narrowing or widening of glottal and supraglottal structures was visible. There are different patterns of glottal and supraglottal configuration during whispering. Although the vocal folds can show partial or total contact over the membranous parts, the lack of additional vibration of the vocal folds suggests that epithelial forces are smaller than with additional vibratory shear stress. Thus, whispering may be considered and allowed for postoperative communication purposes, when patients follow instructions for low-effort whispering.

  13. Release Notes for Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-27

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation [1-3]. It uses the sensitivity profile data for an application as computed by MCNP6 [4-6] along with covariance files [7,8] for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014 [3]. During 2015-2016, Whisper was updated to version 1.1 [9] and is to be included with the upcoming release of MCNP6.2. This document describes the Whisper-1.1 package that will be included with the MCNP6.2 release during 2017. Specific details are provided on the computer systems supported, the software quality assurance (SQA) procedures, installation, and testing. This document does not address other important topics, such as the importance of sensitivity-uncertainty (SU) methods to NCS validation, the theory underlying SU methodology, tutorials on the usage of MCNP-Whisper, practical approaches to using SU methodology to support and extend traditional validation, etc. There are over 50 documents included with Whisper-1.1 and available in the MCNP Reference Collection on the MCNP website (mcnp.lanl.gov) that address all of those topics and more. In this document, however, a complete bibliography of relevant MCNP-Whisper references is provided.

  14. Gallery | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Toggle navigation. Home; ·; About; ·; Speakers; ·; Schedule; ·; Gallery · Logo of the Indian Academy of Sciences; Info for Participants; ·; Downloads; ·; Contact Us. © 2017 Indian Academy of Sciences, Bengaluru.

  15. High-Q Bandpass Comb Filter for Mains Interference Extraction

    Directory of Open Access Journals (Sweden)

    Neycheva T.

    2009-12-01

    Full Text Available This paper presents a simple digital high-Q bandpass comb filter for power-line (PL or other periodical interference extraction. The filter concept relies on a correlated signal average resulting in alternating constructive and destructive spectrum interference i.e. the so-called comb frequency response. The presented filter is evaluated by Matlab simulations with real ECG signal contaminated with low amplitude PL interference. The made simulations show that this filter accurately extract the PL interference. It has high-Q notches only at PL odd harmonics and is appropriate for extraction of any kind of odd harmonic interference including rectangular shape. The filter is suitable for real-time operation with popular low-cost microcontrollers.

  16. High-Q microwave photonic filter with a tuned modulator.

    Science.gov (United States)

    Capmany, J; Mora, J; Ortega, B; Pastor, D

    2005-09-01

    We propose the use of tuned electro-optic or electroabsorption external modulators to implement high-quality (high-Q) factor, single-bandpass photonic filters for microwave signals. Using this approach, we experimentally demonstrate a transversal finite impulse response with a Q factor of 237. This is to our knowledge the highest value ever reported for a passive finite impulse-response microwave photonic filter.

  17. High-Q Antennas with built-in coils

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Svendsen, Simon; Pedersen, Gert Frølund

    2014-01-01

    Efficiency and isolation, at low frequencies (700 MHz), are two of the most important metrics for successful multicommunication implementation. This paper presents an antenna concept, that exhibits a very high isolation between high-Q Tx and Rx antennas at 700 MHz. Furthermore, it is shown how...... coils can be integrating into the antenna structure for obtaining better efficiency. It is shown that by integrated coils into the antenna structure, the efficiency can be improved by 2dB for each antenna....

  18. High-Q gold and silicon nitride bilayer nanostrings

    Science.gov (United States)

    Biswas, T. S.; Suhel, A.; Hauer, B. D.; Palomino, A.; Beach, K. S. D.; Davis, J. P.

    2012-08-01

    Low-mass, high-Q, silicon nitride nanostrings are at the cutting edge of nanomechanical devices for sensing applications. Here we show that the addition of a chemically functionalizable gold overlayer does not adversely affect the Q of the fundamental out-of-plane mode. Instead the device retains its mechanical responsiveness while gaining sensitivity to molecular bonding. Furthermore, differences in thermal expansion within the bilayer give rise to internal stresses that can be electrically controlled. In particular, an alternating current (AC) excites resonant motion of the nanostring. This AC thermoelastic actuation is simple, robust, and provides an integrated approach to sensor actuation.

  19. High-Q terahertz reconfigurable metamaterials using graphene

    Science.gov (United States)

    Arezoomandan, Sara; Sensale Rodriguez, Berardi

    2016-09-01

    We propose and discuss high-Q reconfigurable metamaterials based on graphene. The key components of the device are periodic concentric metallic ring resonators with interdigitated fingers, which are placed in-between the rings and provide for the large Q in the metamaterial, as well as several strategically located gaps where active graphene sheets are placed. We can easily adjust the frequency response of the metamaterial by means of varying a couple of parameters, such as the ring dimensions, number of fingers, etc., but also dynamically by means of varying conductivity in graphene.

  20. Proton structure at high Q/sup 2/

    CERN Document Server

    Nagano, K

    2001-01-01

    The H1 and ZEUS experiments at HERA have measured e/sup +/p and e/sup -/p deep inelastic scattering cross sections at high Q/sup 2/ both for neutral and charged current interactions. Results are presented from data taken during the 1994-1997 (e/sup +/p) and 1998-April 1999 (e/sup -/p) running periods. Preliminary results by H1 from the e/sup +/p data taken during the recent July 1999-2000 running period are also presented.

  1. High Q-factor tunable superconducting HF circuit

    CERN Document Server

    Vopilkin, E A; Pavlov, S A; Ponomarev, L I; Ganitsev, A Y; Zhukov, A S; Vladimirov, V V; Letyago, A G; Parshikov, V V

    2001-01-01

    Feasibility of constructing a high Q-factor (Q approx 10 sup 5) mechanically tunable in a wide range of frequencies (12-63 MHz) vibration circuit of HF range was considered. The tunable circuit integrates two single circuits made using YBaCuO films. The circuit frequency is tuned by changing distance X (capacity) between substrates. Potentiality of using substrates of lanthanum aluminate, neodymium gallate and strontium titanate for manufacture of single circuits was considered. Q-factor of the circuit amounted to 68000 at resonance frequency of 6.88 MHz

  2. Remote Whispering Applying Time Reversal

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Brian Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-16

    The purpose of this project was to explore the use of time reversal technologies as a means for communication to a targeted individual or location. The idea is to have the privacy of whispering in one’s ear, but to do this remotely from loudspeakers not located near the target. Applications of this work include communicating with hostages and survivors in rescue operations, communicating imaging and operational conditions in deep drilling operations, monitoring storage of spent nuclear fuel in storage casks without wires, or clandestine activities requiring signaling between specific points. This technology provides a solution in any application where wires and radio communications are not possible or not desired. It also may be configured to self calibrate on a regular basis to adjust for changing conditions. These communications allow two people to converse with one another in real time, converse in an inaudible frequency range or medium (i.e. using ultrasonic frequencies and/or sending vibrations through a structure), or send information for a system to interpret (even allowing remote control of a system using sound). The time reversal process allows one to focus energy to a specific location in space and to send a clean transmission of a selected signal only to that location. In order for the time reversal process to work, a calibration signal must be obtained. This signal may be obtained experimentally using an impulsive sound, a known chirp signal, or other known signals. It may also be determined from a numerical model of a known environment in which the focusing is desired or from passive listening over time to ambient noise.

  3. High-Q MEMS Resonators for Laser Beam Scanning Displays

    Directory of Open Access Journals (Sweden)

    Ulrich Hofmann

    2012-06-01

    Full Text Available This paper reports on design, fabrication and characterization of high-Q MEMS resonators to be used in optical applications like laser displays and LIDAR range sensors. Stacked vertical comb drives for electrostatic actuation of single-axis scanners and biaxial MEMS mirrors were realized in a dual layer polysilicon SOI process. High Q-factors up to 145,000 have been achieved applying wafer level vacuum packaging technology including deposition of titanium thin film getters. The effective reduction of gas damping allows the MEMS actuator to achieve large amplitudes at high oscillation frequencies while driving voltage and power consumption can be minimized. Exemplarily shown is a micro scanner that achieves a total optical scan angle of 86 degrees at a resonant frequency of 30.8 kHz, which fulfills the requirements for HD720 resolution. Furthermore, results of a new wafer based glass-forming technology for fabrication of three dimensionally shaped glass lids with tilted optical windows are presented.

  4. Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

    National Research Council Canada - National Science Library

    Ioppolo, Tindaro; Ötügen, Volkan; Ayaz, Ulas

    2013-01-01

    ...) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology...

  5. Optimisation of the prism coupling of optical whispering-gallery-mode microcavities

    Science.gov (United States)

    Demchenko, Yu A.; Bilenko, I. A.; Gorodetsky, M. L.

    2017-08-01

    The methods for increasing the coupling efficiency of a prism with spheroidal microcavities, aimed at exciting whisperinggallery modes, have been analytically investigated. Optimal angles of incidence and incident beam parameters are obtained for a spheroidal cavity. The cavity eigenfrequency shift caused by the presence of a prism and the introduced loss by it is calculated.

  6. Whispering-gallery mode lasing from patterned molecular single-crystalline microcavity array

    NARCIS (Netherlands)

    Fang, Hong-Hua; Ding, Ran; Lu, Shi-Yang; Yang, Yue-De; Chen, Qi-Dai; Feng, Jing; Huang, Yong-Zhen; Sun, Hong-Bo; Fang, Honghua

    Organic single-crystalline materials have attracted great attention for laser applications. However, the fabrication of laser resonators and pattern of crystals are still intractable problems. Organic single crystals have been limited to fundamental property studies despite their superior photonic

  7. An Alternative Millimeter Wave Oscillator using a Dielectric Puck in the Whispering Gallery Mode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A majority of millimeter wave based systems used for space exploration, communications and research, require a millimeter wave oscillator. These oscillators have...

  8. High-sensitivity monitoring of micromechanical vibration using optical whispering gallery mode resonators

    Energy Technology Data Exchange (ETDEWEB)

    Schliesser, A; Anetsberger, G; Riviere, R; Arcizet, O; Kippenberg, T J [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)], E-mail: tjk@mpq.mpg.de

    2008-09-15

    The inherent coupling of optical and mechanical modes in high finesse optical microresonators provides a natural, highly sensitive transduction mechanism for micromechanical vibration. Using homodyne and polarization spectroscopy techniques, we achieve shot-noise limited displacement sensitivities of 10{sup -19} m Hz{sup -1/2}. In an unprecedented manner, this enables the detection and study of a variety of mechanical modes, which are identified as radial breathing, flexural and torsional modes using three-dimensional finite element modeling. Furthermore, a broadband equivalent displacement noise is measured and found to agree well with models for thermorefractive noise in silica dielectric cavities. Implications for ground-state cooling, displacement sensing and Kerr squeezing are discussed.

  9. Adiabatic tapered optical fiber fabrication for exciting whispering gallery modes in microcavities

    Science.gov (United States)

    Chenari, Z.; Latifi, H.; Hashemi, R. S.; Doroudmand, F.

    2014-05-01

    This article demonstrates an investigation and analysis of a tapered fiber fabrication using an etchant droplet method. To achieve precise control on process, a two-step etching method is proposed (using 48% concentration of HF acid and Buffered HF) which results in low-loss adiabatic tapered fiber. A spectrum analysis monitoring in addition to a microscopy system was used to verify the etching progress. Tapers with losses less than 0.4 dB in air and 4.5 dB in water are demonstrated. A biconical fiber taper fabricated using this method was used to excite the WGMs on a microsphere surface in aquatic environment.

  10. Interfacing Whispering-Gallery Microresonators and Free Space Light With Cavity Enhanced Rayleigh Scattering

    Science.gov (United States)

    2014-09-17

    air flow and mechanical vibrations). This significantly limits the practical use of fiber-taper-coupled WGMRs. Prism and on-chip waveguide couplers are...evanescent field channel exists for extracting light from WGMs, and for coupling light into WGMs using prisms , tapered fibers or waveguides21–25...more stable, but their applications are limited by the bulkiness of prism system, or the requirement of additional optics to couple light into the on

  11. Towards a fully integrated optical gyroscope using whispering gallery modes resonators

    Science.gov (United States)

    Amrane, T.; Jager, J.-B.; Jager, T.; Calvo, V.; Léger, J.-M.

    2017-11-01

    Since the developments of lasers and the optical fibers in the 70s, the optical gyroscopes have been subject to an intensive research to improve both their resolution and stability performances. However the best optical gyroscopes currently on the market, the ring laser gyroscope and the interferometer fiber optic gyroscope are still macroscopic devices and cannot address specific applications where size and weight constraints are critical. One solution to overcome these limitations could be to use an integrated resonator as a sensitive part to build a fully Integrated Optical Resonant Gyroscope (IORG). To keep a high rotation sensitivity, which is usually degraded when downsizing this kind of optical sensors based on the Sagnac effect, the resonator has to exhibit a very high quality factor (Q): as detailed in equation (1) where the minimum rotation rate resolution for an IORG is given as a function of the resonator characteristics (Q and diameter D) and of the global system optical system characteristics (i.e. SNR and bandwidth B), the higher the Q×D product, the lower the resolution.

  12. Spatial refractive index sensor using whispering gallery modes in an optically trapped microsphere

    NARCIS (Netherlands)

    Zijlstra, P.; Zijlstra, Peter; van der Molen, K.L.; Mosk, Allard

    2007-01-01

    The authors propose the use of an optically trapped, dye doped polystyrene microsphere for spatial probing of the refractive index at any position in a fluid. Using the dye embedded in the microsphere as an internal broadband excitation source the authors eliminated the need for a tunable excitation

  13. Tuning whispering gallery mode lasing from self-assembled polymer droplets

    National Research Council Canada - National Science Library

    Ta, Van Duong; Chen, Rui; Sun, Han Dong

    2013-01-01

    .... The droplets are self-assembly inside an elastic medium. By incorporating different dye molecules into the droplets, optically pumped lasing with selective wavelengths in a range of about 100 nm are achieved...

  14. High-Q Supercavity Modes in Subwavelength Dielectric Resonators.

    Science.gov (United States)

    Rybin, Mikhail V; Koshelev, Kirill L; Sadrieva, Zarina F; Samusev, Kirill B; Bogdanov, Andrey A; Limonov, Mikhail F; Kivshar, Yuri S

    2017-12-15

    Recent progress in nanoscale optical physics is associated with the development of a new branch of nanophotonics exploring strong Mie resonances in dielectric nanoparticles with a high refractive index. The high-index resonant dielectric nanostructures form building blocks for novel photonic metadevices with low losses and advanced functionalities. However, unlike extensively studied cavities in photonic crystals, such dielectric resonators demonstrate low quality factors (Q factors). Here, we uncover a novel mechanism for achieving giant Q factors of subwavelength nanoscale resonators by realizing the regime of bound states in the continuum. In contrast to the previously suggested multilayer structures with zero permittivity, we reveal strong mode coupling and Fano resonances in homogeneous high-index dielectric finite-length nanorods resulting in high-Q factors at the nanoscale. Thus, high-index dielectric resonators represent the simplest example of nanophotonic supercavities, expanding substantially the range of applications of all-dielectric resonant nanophotonics and meta-optics.

  15. High Q, Miniaturized LCP-Based Passive Components

    KAUST Repository

    Shamim, Atif

    2014-10-16

    Various methods and systems are provided for high Q, miniaturized LCP-based passive components. In one embodiment, among others, a spiral inductor includes a center connection and a plurality of inductors formed on a liquid crystal polymer (LCP) layer, the plurality of inductors concentrically spiraling out from the center connection. In another embodiment, a vertically intertwined inductor includes first and second inductors including a first section disposed on a side of the LCP layer forming a fraction of a turn and a second section disposed on another side of the LCP layer. At least a portion of the first section of the first inductor is substantially aligned with at least a portion of the second section of the second inductor and at least a portion of the first section of the second inductor is substantially aligned with at least a portion of the second section of the first inductor.

  16. Digitally Programmable High-Q Voltage Mode Universal Filter

    Directory of Open Access Journals (Sweden)

    D. Singh

    2013-12-01

    Full Text Available A new low-voltage low-power CMOS current feedback amplifier (CFA is presented in this paper. This is used to realize a novel digitally programmable CFA (DPCFA using transistor arrays and MOS switches. The proposed realizations nearly allow rail-to-rail swing capability at all the ports. Class-AB output stage ensures low power dissipation and high current drive capability. The proposed CFA/ DPCFA operates at supply voltage of ±0.75 V and exhibits bandwidth better than 95 MHz. An application of the DPCFA to realize a novel voltage mode high-Q digitally programmable universal filter (UF is given. Performances of all the proposed circuits are verified by PSPICE simulation using TSMC 0.25μm technology parameters.

  17. Ultra-high-Q nanobeam cavity design in Diamond

    CERN Document Server

    Bayn, Igal; Kalish, Rafi

    2010-01-01

    A novel nanobeam design with a triangular cross-section is proposed. This design makes possible implementing nanocavities with improved optical properties. The dependence of a diamond-based cavity quality factor Q and mode volume Vm on geometry parameter space are studied via 3D FDTD computations. An ultra-high-Q cavity with Q\\aprox 2.51 \\times 10^6 and Vm=1.06 \\times ({\\lambda}/n)^3 is predicted. The mode preferential radiation is upward. The implications on the potential applications are discussed. The proposed nanobeam enables fabrication of the cavity without relying on a pre-existing free-standing diamond membrane as required in most previous approaches.

  18. Macroscopic quantum electrodynamics of high-Q cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khanbekyan, Mikayel

    2009-10-27

    In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the

  19. The Child Whisperer: Effective Parenting Strategies Adapted from "The Dog Whisperer"

    Science.gov (United States)

    McKinney, Cliff; Durr, Brandi

    2013-01-01

    Behavior modification with children has been popularized through television shows such as "Super Nanny" and "Nanny 911". The popularity of these shows may be related to the demand parents have for improving their children's behavior. Interestingly, an approach adopted by "The Dog Whisperer" may prove effective when used with children. The purpose…

  20. Thermal Loss of High-Q Antennas in Time Domain vs. Frequency Domain Solver

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert Frølund

    2014-01-01

    High-Q structures pose great challenges to their loss simulations in Time Domain Solvers (TDS). Therefore, in this work the thermal loss of high-Q antennas is calculated both in TDS and Frequency Domain Solver (FDS), which are then compared with each other and with the actual measurements....... The thermal loss calculation in FDS is shown to be more accurate for high-Q antennas....

  1. Whispers from the Edge of Physics

    Science.gov (United States)

    Andersson, Nils

    2017-09-01

    Neutron stars involve extreme physics which is difficult (perhaps impossible) to explore in laboratory experiments. We have to turn to astrophysical observations, and try to extract information from the entire range of the electromagnetic spectrum. In addition, neutron stars may radiate gravitational waves through a range of scenarios. This brief summary outlines some of the main ideas, focussing on what we do and do not know, and the challenges involved in trying to catch these faint whispers from the very edge of physics are described.

  2. Rael Artel Gallery Tartus ja Varssavis

    Index Scriptorium Estoniae

    2006-01-01

    Rael Artel Gallery : Non-Profit Project Space'i tegevusest Tartus. 27.04-27.05. 2006 Varssavis Warszawski Aktyw Artystov'i ruumides näitus "Estonian Video Art. The blood project", osalesid Flo Kasearu, Gert Hatsukov, Külli K. Kaats, Allan Tõnissoo, Marko Nautras, Tanja Muravskaja ja Airi Triisberg

  3. Lecture Notes on Criticality Safety Validation Using MCNP & Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    Training classes for nuclear criticality safety, MCNP documentation. The need for, and problems surrounding, validation of computer codes and data area considered first. Then some background for MCNP & Whisper is given--best practices for Monte Carlo criticality calculations, neutron spectra, S(α,β) thermal neutron scattering data, nuclear data sensitivities, covariance data, and correlation coefficients. Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the Monte Carlo radiation transport package MCNP. Whisper's methodology (benchmark selection – Ck's, weights; extreme value theory – bias, bias uncertainty; MOS for nuclear data uncertainty – GLLS) and usage are discussed.

  4. [Physical diagnostic procedures: whispered speech and tuning fork test].

    Science.gov (United States)

    Grote, J J; de Laat, J A

    1998-08-08

    Hearing impairment occurs in 10% of the Dutch population and may lead to major communication problems and even social isolation. A good method to detect hearing loss in a general practice is the screening audiometer. The treating physician may further use the whispered speech test and tuning fork tests which together give a good impression of the severity and the nature of the hearing loss if any. The whispered speech test is best performed in the standardized form according to the guideline 'Slechthorendheid' [hardness of hearing] of the Dutch College of General Practitioners (NHG), in which certain combinations of letters are recommended. The tuning fork tests according to Rinne and Weber indicate a difference in perception and conduction deafness, and are decisive for any hearing asymmetry. Use of the whispered speech test and of the tuning fork tests is recommended for adults and children from the age of 7.

  5. A new microphone system for near whispering.

    Science.gov (United States)

    Choi, Sungjoon; Moon, Wonkyu; Lee, Jeong Hyun

    2003-08-01

    A new microphone system was developed to monitor the human voice near the microphone in a noisy environment. The system is equipped with two special functions in addition to the usual microphone functions: reduction of air-blow effects by the mouth and focused reception to a sound source. A wind filter was developed to reduce the air-blow effects from the mouth during speaking. This filter is a plate perforated by an array of small holes; the method used to design the filter is also presented. To achieve focused reception, four microphones were used in conjunction with a new signal-processing method. The proposed signal-processing method effectively increases the directivity in the desired direction. Additionally, it provides the system with focusing on the source since the source is located adjacent to the system. A prototype of the proposed system was fabricated and subjected to performance tests. The results showed that air-blow effects can be reduced by up to 20 dB and the directional gain is more than 4 dB. The proposed microphone system shows such good performance that it can be used in mobile phones for whispering communication.

  6. Numerical study of long Josephson junctions coupled to a high-Q cavity

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Pedersen, Niels Falsig; Davidson, A.

    1990-01-01

    Long Josephson junctions coupled to a high-Q resonator are studied numerically and compared with recently published approximative results, obtained by using a perturbative approach to the fluxon motion in the junction. The similarities and differences in the two approaches are discussed.......Long Josephson junctions coupled to a high-Q resonator are studied numerically and compared with recently published approximative results, obtained by using a perturbative approach to the fluxon motion in the junction. The similarities and differences in the two approaches are discussed....

  7. High-resolution photon-scanning tunneling microscope measurements of the whispering gallery modes in a cylindrical microresonator

    NARCIS (Netherlands)

    Klunder, D.J.W.; Balistreri, M.L.M.; Blom, F.C.; Driessen, A.; Hoekstra, Hugo; Kuipers, L.; van Hulst, N.F.

    2000-01-01

    A detailed analysis of spatio-spectral photon scanning tunneling microscope scans of the light intensity inside a cylindrical microresonator has been carried out. By comparing the experimental results with theory, it is shown that the inclusion of spectral mode-beat phenomena is crucial for an

  8. Frequency tuning of single photons from a whispering-gallery mode resonator to MHz-wide transitions

    DEFF Research Database (Denmark)

    Schunk, G.; Vogl, U.; Sedlmeir, F.

    2016-01-01

    Quantum repeaters rely on interfacing flying qubits with quantum memories. The most common implementations include a narrowband single photon matched in bandwidth and central frequency to an atomic system. Previously, we demonstrated the compatibility of our versatile source of heralded single ph...

  9. Thermal loss and soldering effect study of high-Q antennas in handheld devices

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Jagielski, Ole; Pedersen, Gert Frølund

    2013-01-01

    High-Q antennas are attractive because, besides being narrow-band, they have the advantage of being more compact and therefore occupy less volume in a mobile device. However, they can become very lossy especially at lower frequencies. In this paper it is investigated how low a thermal loss...

  10. Tunable High-Q N-Path Band-Pass Filters: Modeling and Verification

    NARCIS (Netherlands)

    Ghaffari, A.; Klumperink, Eric A.M.; Soer, M.C.M.; Nauta, Bram

    2011-01-01

    Abstract—A differential single-port switched-RC N-path filter with band-pass characteristic is proposed. The switching frequency defines the center frequency, while the RC-time and duty cycle of the clock define the bandwidth. This allows for high-Q highly tunable filters which can for instance be

  11. High-Q plasmonic infrared absorber for sensing of molecular resonances in hybrid lead halide perovskites

    Science.gov (United States)

    Dayal, Govind; Solanki, Ankur; Chin, Xin Yu; Sum, Tze Chien; Soci, Cesare; Singh, Ranjan

    2017-08-01

    Plasmonic resonances in sub-wavelength metal-dielectric-metal cavities have been shown to exhibit strong optical field enhancement. The large field enhancements that occur in sub-wavelength regions of the cavity can drastically boost the performance of microcavity based detectors, electromagnetic wave absorbers, metasurface hologram, and nonlinear response of the material in a cavity. The performance efficiencies of these plasmonic devices can be further improved by designing tunable narrow-band high-Q cavities. Here, we experimentally and numerically demonstrate high-Q resonances in metal-dielectric-metal cavity consisting of an array of conductively coupled annular and rectangular apertures separated from the bottom continuous metal film by a thin dielectric spacer. Both, the in-plane and out of plane coupling between the resonators and the continuous metal film have been shown to support fundamental and higher order plasmonic resonances which result in high-Q response at mid-infrared frequencies. As a sensor application of the high-Q cavity, we sense the vibrational resonances of an ultrathin layer of solution-processed organic-inorganic hybrid lead halide perovskites.

  12. Conical and bi-conical high-Q optical nanofiber microcoil resonator

    OpenAIRE

    Xu, Fei; Horak, Peter; Brambilla, Gilberto

    2006-01-01

    The Q-factor of the optical nanowire microcoil resonator is calculated and compared for different geometries. The results suggest that the Q-factor is very sensitive to the coupling conditions and high-Q resonators can be obtained more easily when the geometry of the nanowire microcoil resonator or its coupling contour has a bi-conical profile.

  13. Conical and biconical ultra-high-Q optical-fiber nanowire microcoil resonator.

    Science.gov (United States)

    Xu, Fei; Horak, Peter; Brambilla, Gilberto

    2007-02-01

    New 3D geometries of the optical nanowire microcoil resonator are suggested and investigated theoretically. The dependence of the Q factor on coupling parameters is calculated and compared for three different profiles. Results suggest that ultra-high-Q resonators can be fabricated more easily when the nanowire microcoil resonator has a biconical profile.

  14. Theoretical and experimental study of high-Q resonant modes in terahertz optical systems

    NARCIS (Netherlands)

    Jellema, Willem; Withington, S.; Trappe, Neil; Murphy, J. A.; Wild, Wolfgang

    2004-01-01

    The existence of multiple reflections in terahertz optical system causes numerous problems in applications ranging from astronomical to medical instrumentation. We have performed a detailed theoretical study, using waveguide and free-space modal matching, of the high-Q modes that appear on THz

  15. Materials selection for low temperature processed high Q resonators using ashby approach

    NARCIS (Netherlands)

    Kazmi, S.N.R.; Salm, Cora; Schmitz, Jurriaan

    2009-01-01

    MicroElectroMechanical Systems (MEMS) is an emerging class of microfabrication technology that can truly be anticipated as an enabling technology for future radio frequency (RF) communications. This work focuses on the material selection using the Ashby approach for the high-Q resonators that need

  16. Significance of parametric spectral ratio methods in detection and recognition of whispered speech

    Science.gov (United States)

    Mathur, Arpit; Reddy, Shankar M.; Hegde, Rajesh M.

    2012-12-01

    In this article the significance of a new parametric spectral ratio method that can be used to detect whispered speech segments within normally phonated speech is described. Adaptation methods based on the maximum likelihood linear regression (MLLR) are then used to realize a mismatched train-test style speech recognition system. This proposed parametric spectral ratio method computes a ratio spectrum of the linear prediction (LP) and the minimum variance distortion-less response (MVDR) methods. The smoothed ratio spectrum is then used to detect whispered segments of speech within neutral speech segments effectively. The proposed LP-MVDR ratio method exhibits robustness at different SNRs as indicated by the whisper diarization experiments conducted on the CHAINS and the cell phone whispered speech corpus. The proposed method also performs reasonably better than the conventional methods for whisper detection. In order to integrate the proposed whisper detection method into a conventional speech recognition engine with minimal changes, adaptation methods based on the MLLR are used herein. The hidden Markov models corresponding to neutral mode speech are adapted to the whispered mode speech data in the whispered regions as detected by the proposed ratio method. The performance of this method is first evaluated on whispered speech data from the CHAINS corpus. The second set of experiments are conducted on the cell phone corpus of whispered speech. This corpus is collected using a set up that is used commercially for handling public transactions. The proposed whisper speech recognition system exhibits reasonably better performance when compared to several conventional methods. The results shown indicate the possibility of a whispered speech recognition system for cell phone based transactions.

  17. Wireless Hybrid Identification and Sensing Platform for Equipment Recovery (WHISPER) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Systems & Technologies proposed WHISPER (Wireless Hybrid Identification and Sensing Platform for Equipment Recovery) solution to NASA's need for...

  18. High-Q photonic crystal cavities in all-semiconductor photonic crystal heterostructures

    Science.gov (United States)

    Bushell, Z. L.; Florescu, M.; Sweeney, S. J.

    2017-06-01

    Photonic crystal cavities enable the realization of high Q-factor and low mode-volume resonators, with typical architectures consisting of a thin suspended periodically patterned layer to maximize confinement of light by strong index guiding. We investigate a heterostructure-based approach comprising a high refractive index core and lower refractive index cladding layers. While confinement typically decreases with decreasing index contrast between the core and cladding layers, we show that, counterintuitively, due to the confinement provided by the photonic band structure in the cladding layers, it becomes possible to achieve Q factors >104 with only a small refractive index contrast. This opens up opportunities for implementing high-Q factor cavities in conventional semiconductor heterostructures, with direct applications to the design of electrically pumped nanocavity lasers using conventional fabrication approaches.

  19. The Design of High-Q Sallen-Key Biquads with Unity-Gain Buffer Amplifiers

    DEFF Research Database (Denmark)

    Gaunholt, Hans; Guldbrandsen, Birthe

    1997-01-01

    and to implement the Sallen- Key biquad even in the high-Q case with reasonable sensitivities. The method is based on the unity gain version of the biquad and as unity gain buffer amplifiers are readily manufactured in integrated circuit technology the results may be very useful in the fabrication of integrated...... analog filters in voltage-mode as well as current-mode technology. As an example we will choose the band-pass biquad as biquads of this type often has to be designed with high-Q values. The results in the band-pass case may readily be transferred to the low-pass and high-pass cases....

  20. First-principles method for high-$Q$ photonic crystal cavity mode calculations

    CERN Document Server

    Mahmoodian, Sahand; Poulton, Christopher G; Dossou, Kokou B; Botten, Lindsay C; McPhedran, Ross C; de Sterke, C Martijn

    2012-01-01

    We present a first-principles theory to compute radiation properties of ultra-high quality factor photonic crystal (PC) cavities using a basis of bound PC waveguide states. This method is used to compute the far-field radiation pattern and quality factor of cavity modes $\\sim 100$ times more rapidly than conventional finite-difference time domain methods. Our method provides a simple rule for engineering the PC cavity far-field radiation pattern in high $Q$ cavities.

  1. STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

    Science.gov (United States)

    2016-11-02

    STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...setup. At the end of this program, we had built the vacuum system, specialized cold atom chamber and were working on the fiber epoxy mount for the...Triangle Park, NC 27709-2211 Tapered Fibers, Cold atoms , Nonlinear Optics REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR

  2. East Side Gallery - en analyze af betydningstilskrivning

    OpenAIRE

    Lyngsø Knudsen, Lene

    2013-01-01

    In March 2013, the city of Berlins local government gave permission to remove 23 meters of East Side Gallery - a 1.3 kilometer section of the Berlin Wall. This was to make room for apartment buildings, and to reconstruct an old bridge across the river Spree. This caused many people to riot for the preservation of the Wall. They argued that the Wall and it’s sorroundings is a part of the citys history - a part that must not be forgotten. This conflict is the main subject of this assignment....

  3. Early results from the Whisper instrument on Cluster: An overview

    DEFF Research Database (Denmark)

    Decreau, P.M.E.; Fergeau, P.; Krasnoselskikh, V.

    2001-01-01

    The Whisper instrument yields two data sets: (i) the electron density determined via the relaxation sounder, and (ii) the spectrum of natural plasma emissions in the frequency band 2-80 kHz. Both data sets allow for the three-dimensional exploration of the magnetosphere by the Cluster mission....... The total electron density can be derived unambiguously by the sounder in most magnetospheric regions, provided it is in the range of 0.25 to 80 cm(-3). The natural emissions already observed by earlier spacecraft are fairly well measured by the Whisper instrument, thanks to the digital technology which...... largely overcomes the limited telemetry allocation. The natural emissions are usually related to the plasma frequency, as identified by the sounder, and the combination of an active sounding operation and a passive survey operation provides a time resolution for the total density determination of 2.2 s...

  4. The Authors Gallery: A Meaningful Integration of Technology and Writing

    Science.gov (United States)

    Martin, Deb

    2008-01-01

    In this article, the author first explains what an authors gallery is and suggests additional uses and modifications. Next, readers are taken through a day-by-day description of creating the gallery while having the theory behind this pedagogical choice explained. The step-by-step discussion is supported with student examples and concepts drawn…

  5. Science Outreach through Art: A Journal Article Cover Gallery

    Science.gov (United States)

    McCullough, Ian

    2015-01-01

    Research faculty journal covers were used to create a gallery in the Science & Technology branch library at the University of Akron. The selection, presentation, and promotion process is shared along with copyright considerations and a review of galleries used for library outreach. The event and display was a great success attracting faculty…

  6. Coral Reefs: A Gallery Program, Grades 7-12.

    Science.gov (United States)

    National Aquarium in Baltimore, MD. Dept. of Education.

    Gallery classes at the National Aquarium in Baltimore give the opportunity to study specific aquarium exhibits which demonstrate entire natural habitats. The coral reef gallery class features the gigantic western Atlantic coral reef (325,000 gallons) with over 1,000 fish. The exhibit simulates a typical Caribbean coral reef and nearby sandy…

  7. Direct Writing of Photonic Structures by Two-Photon Polymerization

    Directory of Open Access Journals (Sweden)

    Li Yan

    2013-11-01

    Full Text Available Single-mode dielectric-loaded surface plasmon-polariton nanowaveguides with strong mode confinement at excitation wavelength of 830 nm and high-Q polymer whispering gallery mode microcavities with surface roughness less than 12 nm have been directly written by two-photon polymerization, which pave the way to fabricate 3D plasmonic photonic structures by direct laser writing.

  8. Speaker-Sex Discrimination for Voiced and Whispered Vowels at Short Durations.

    Science.gov (United States)

    Smith, David R R

    2016-01-01

    Whispered vowels, produced with no vocal fold vibration, lack the periodic temporal fine structure which in voiced vowels underlies the perceptual attribute of pitch (a salient auditory cue to speaker sex). Voiced vowels possess no temporal fine structure at very short durations (below two glottal cycles). The prediction was that speaker-sex discrimination performance for whispered and voiced vowels would be similar for very short durations but, as stimulus duration increases, voiced vowel performance would improve relative to whispered vowel performance as pitch information becomes available. This pattern of results was shown for women's but not for men's voices. A whispered vowel needs to have a duration three times longer than a voiced vowel before listeners can reliably tell whether it's spoken by a man or woman (∼30 ms vs. ∼10 ms). Listeners were half as sensitive to information about speaker-sex when it is carried by whispered compared with voiced vowels.

  9. Applications of High-Q Microresonators in Cavity Optomechanics and Nonlinear Photonics

    Science.gov (United States)

    Jiang, Wei C.

    Optical microresonators confining light to small volumes are indispensable for a great variety of studies and applications. This thesis is devoted to a study of cavity optomechanical and nonlinear optical phenomena in high-Q microresonators with different materials and structures. Based on that, it proposes and demonstrates several novel schemes and device platforms that exhibit great potential for various applications ranging from frequency metrology and quantum photonics, to information processing and sensing. The thesis starts with a demonstration of a high-frequency (above 1 GHz) regenerative optomechanical oscillator based on a 2-mum-radius high-Q silicon microdisk resonator in the silicon-on-insulator platform with an ultra-low threshold pump power at room temperature and atmosphere. It then continues to explore the cavity optomechanics in single-crystal lithium niobate. A compact lithium niobate microdisk optomechanical resonator with high optical and mechanical qualities, large optomechanical coupling, and high mechanical frequency is achieved, enabling the demonstration of regenerative oscillation in the ambience. Meanwhile, I propose and investigate a novel approach for single molecule detection that utilizes the optical spring effect in a high-Q coherent optomechanical oscillator to dramatically enhance the sensing resolution by orders of magnitude compared with conventional resonator-based approaches. In particular, a high-Q silica microsphere is employed to experimentally demonstrate the detection of single Bovine Serum Albumin proteins with a molecular weight of 66 kDalton at a signal-to-noise ratio of 16.8. On the other hand, the thesis focuses on the theoretical and experimental investigation of the generation of high-purity bright photon pairs in a silicon microdisk based on the cavity enhanced four-wave mixing. The device is able to produce multiple photon pairs at different wavelengths in the telecom band with a high spectral brightness of 6.24 x

  10. Coupled high Q-factor Surface Nanoscale Axial Photonics (SNAP) microresonators

    CERN Document Server

    Sumetsky, M; DiGiovanni, D J; Dulashko, Y; Fini, J M; Monberg, E

    2011-01-01

    We experimentally demonstrate series of identical two, three, and five coupled high Q-factor Surface Nanoscale Axial Photonics (SNAP) microresonators formed by periodic nanoscale variation of the optical fiber radius. These microresonators are fabricated with a 100 \\mum period along an 18 \\mum radius optical fiber. The axial FWHM of these microresonators is 80 \\mum and their Q-factor exceeds 107. In addition, we demonstrate a SNAP microresonator with the axial FWHM as small as 30 \\mum and the axial FWHM of the fundamental mode as small as 10 \\mum. These results may potentially enable the dense integration of record low loss coupled photonic microdevices on the optical fiber platform.

  11. Two-dimensional Josephson junction arrays coupled through a high-Q cavity

    DEFF Research Database (Denmark)

    Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.

    2001-01-01

    The problem of disordered two-dimensional arrays of underdamped Josephson junctions is addressed. Our simulations show that when coupled to a high-Q cavity, the array exhibits synchronized behavior, and the power emitted can be considerably increased once enough junctions are activated to pump...... emission frequency of the junctions and the cavity resonant frequency. We show with a simple argument that we can predict the scaling behavior of disorder with the size of the array. The consequences for the design of microwave oscillators in the Gigahertz region are discussed...

  12. Numerical and Experimental Study of the Q Factor of High-Q Micropillar Cavities

    DEFF Research Database (Denmark)

    Gregersen, Niels; Reitzenstein, S.; Kistner, C.

    2010-01-01

    Micropillar cavities are potential candidates for high-efficiency single-photon sources and are testbeds for cavity quantum electrodynamics experiments. In both applications a high quality (Q) factor is desired. It was recently shown that the Q of high-Q semiconductor micropillar cavities exhibit...... to the effective reflectivity of the fundamental mode arising from coupling to scattering channels involving higher-order cavity modes and propagating Bloch modes in the distributed Bragg reflectors (DBRs). We show how these weak contributions lead to strong variations of the Q factor, and we relate the average...

  13. Charged Particle Production in High Q2 Deep-Inelastic Scattering at HERA

    CERN Document Server

    Aaron, F.D.; Alexa, C.; Andreev, V.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martisikova, M.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Prideaux, P.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salek, D.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smiljanic, Ivan; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Stiewe, J.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Utkin, D.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2007-01-01

    The average charged track multiplicity and the normalised distribution of the scaled momentum, $\\xp$, of charged final state hadrons are measured in deep-inelastic $\\ep$ scattering at high $Q^2$ in the Breit frame of reference. The analysis covers the range of photon virtuality $100 < Q^2 < 20 000 \\GeV^{2}$. Compared with previous results presented by HERA experiments this analysis has a significantly higher statistical precision and extends the phase space to higher $Q^{2}$ and to the full range of $\\xp$. The results are compared with $e^+e^-$ annihilation data and with various calculations based on perturbative QCD using different models of the hadronisation process.

  14. High-Q X-band distributed Bragg resonator utilizing an aperiodic alumina plate arrangement.

    Science.gov (United States)

    Bale, Simon; Everard, Jeremy

    2010-01-01

    This paper describes a high-Q X-band distributed Bragg resonator that uses an aperiodic arrangement of non-lambda/4 low loss alumina plates mounted in a cylindrical waveguide. An ABCD parameter waveguide model was developed to simulate and optimize the cavity. The dielectric plates and air waveguide dimensions were optimized to achieve maximum quality factor by redistributing the energy loss within the cavity. An unloaded quality factor (Q(0)) of 196,000 was demonstrated at 9.93 GHz.

  15. Collect (Galerie Marzee) at the Saatchi Gallery (London)

    OpenAIRE

    Boyd, JMB

    2011-01-01

    COLLECT is the premier annual fair in Europe for international contemporary craft of museum quality.\\ud \\ud Originally held at the V&A, and now re launched at the Saatchi Gallery in London, COLLECT has an enviable reputation as a major event on the international cultural calendar, with a loyal audience of private collectors and museum curators.\\ud \\ud Jonathan Boyd's work was displayed by Galerie Marzee (the worlds largest comtemporary jewllery gallery). His work exploreed the themes and narr...

  16. Advertising identities: virtual galleries as places of identity

    Directory of Open Access Journals (Sweden)

    Alexandra Zontea

    2010-10-01

    Full Text Available This paper is focused on the public presentation of self through virtual art galleries, singling out the field of photography. Photography has always been disputed as being part of the highbrow arts because of its popular character. Today, anyone who owes a photo camera can experience photography as art, without a rigorous training. Everybody is able to expose the photos freely to a large number of people, on the Internet. Consequently, the Internet opens up a virtual space, in which photo artists and amateurs can promote their works and exhibit them in a personal online gallery, which represents their place in the virtual vastness. Therefore, my research approaches the matter of the virtual gallery as an identitary place, being focused on finding out why artists choose to exhibit in virtual galleries. I asked myself what are the new functions of the virtual art galleries?Are they understood as online markers that distinguish the owners in these virtual environments? In other words, are these personal galleries a way of expressing online identities?

  17. How to Tell Beans from Farmers: Cues to the Perception of Pitch Accent in Whispered Norwegian

    Directory of Open Access Journals (Sweden)

    Hannele Nicholson

    2004-01-01

    Full Text Available East Norwegian employs pitch accent contours in order to make lexical distinctions. This paper researches listeners' ability to make lexical distinctions in the absence of f0 (ie. whispered speech as the listener attempts to determine which pitch accent word token best fits into a whispered ambiguous utterance in spoken Norwegian. The results confirm that local syntactic context alone is not a reliable cue to assist in lexical selection and concur with Fintoft (1970 in suggesting that listeners utilise a separate prosodic cue, possibly syllable duration or intensity, to make the pitch accent distinction in whispered speech.

  18. Charged particle production in high Q{sup 2} deep-inelastic scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, F.D.; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Aktas, A. [DESY, Hamburg (DE)] (and others)

    2007-05-15

    The average charged track multiplicity and the normalised distribution of the scaled momentum, x{sub p}, of charged final state hadrons are measured in deep-inelastic ep scattering at high Q{sup 2} in the Breit frame of reference. The analysis covers the range of photon virtuality 100 < Q{sup 2} < 20 000 GeV{sup 2}. Compared with previous results presented by HERA experiments this analysis has a significantly higher statistical precision and extends the phase space to higher Q{sup 2} and to the full range of x{sub p}. The results are compared with e{sup +}e{sup -} annihilation data and with various calculations based on perturbative QCD using different models of the hadronisation process. (orig.)

  19. Fabrication of high-Q microresonators in dielectric materials using a femtosecond laser: Principle and applications

    Science.gov (United States)

    Wang, Min; Lin, Jin-Tian; Xu, Ying-Xin; Fang, Zhi-Wei; Qiao, Ling-Ling; Liu, Zheng-Ming; Fang, Wei; Cheng, Ya

    2017-07-01

    Femtosecond laser micromachining has been a promising technique for fabricating three-dimensional (3D) micro/nano-structures in various kinds of dielectric materials with unprecedented spatial resolutions as well as flexibility in terms of the geometry and the materials can be processed. This unique capability opens opportunities for fabrication of 3D high-quality (Q) microresonators, which are one of the key elements in modern photonic applications. Here, we review the recent progress in fabrication of high-Q microresonators on glass and crystalline substrates by employing femtosecond laser direct writing. We demonstrate the applications of the fabricated microresonators in generating low-threshold lasers, high-sensitivity chemical sensing and nonlinear optical wavelength conversion.

  20. Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Dhakal, Pashupati [JLAB; Ciovati, Gianluigi [JLAB; Kneisel, Peter [JLAB; Myneni, Ganapati Rao [JLAB

    2014-07-01

    Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×1010 at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities depth profiles were made on samples heat treated with the cavities.

  1. Vertical integration of high-Q silicon nitride microresonators into silicon-on-insulator platform.

    Science.gov (United States)

    Li, Qing; Eftekhar, Ali A; Sodagar, Majid; Xia, Zhixuan; Atabaki, Amir H; Adibi, Ali

    2013-07-29

    We demonstrate a vertical integration of high-Q silicon nitride microresonators into the silicon-on-insulator platform for applications at the telecommunication wavelengths. Low-loss silicon nitride films with a thickness of 400 nm are successfully grown, enabling compact silicon nitride microresonators with ultra-high intrinsic Qs (~ 6 × 10(6) for 60 μm radius and ~ 2 × 10(7) for 240 μm radius). The coupling between the silicon nitride microresonator and the underneath silicon waveguide is based on evanescent coupling with silicon dioxide as buffer. Selective coupling to a desired radial mode of the silicon nitride microresonator is also achievable using a pulley coupling scheme. In this work, a 60-μm-radius silicon nitride microresonator has been successfully integrated into the silicon-on-insulator platform, showing a single-mode operation with an intrinsic Q of 2 × 10(6).

  2. Versatile tissue lasers based on high-Q Fabry-Pérot microcavities.

    Science.gov (United States)

    Chen, Yu-Cheng; Chen, Qiushu; Zhang, Tingting; Wang, Wenjie; Fan, Xudong

    2017-01-31

    Biolasers are an emerging technology for next generation biochemical detection and clinical applications. Progress has recently been made to achieve lasing from biomolecules and single living cells. Tissues, which consist of cells embedded in an extracellular matrix, mimic more closely the actual complex biological environment in a living body and therefore are of more practical significance. Here, we developed a highly versatile tissue laser platform, in which tissues stained with fluorophores are sandwiched in a high-Q Fabry-Pérot microcavity. Distinct lasing emissions from muscle and adipose tissues stained respectively with fluorescein isothiocyanate (FITC) and boron-dipyrromethene (BODIPY), and hybrid muscle/adipose tissue with dual staining were achieved with a threshold of only ∼10 μJ mm-2. Additionally, we investigated how the tissue structure/geometry, tissue thickness, and staining dye concentration affect the tissue laser. Lasing emission from FITC conjugates (FITC-phalloidin) that specifically target F-actin in muscle tissues was also realized. It is further found that, despite the large fluorescence spectral overlap between FITC and BODIPY in tissues, their lasing emissions could be clearly distinguished and controlled due to their narrow lasing bands and different lasing thresholds, thus enabling highly multiplexed detection. Our tissue laser platform can be broadly applicable to various types of tissues/diseases. It provides a new tool for a wide range of biological and biomedical applications, such as diagnostics/screening of tissues and identification/monitoring of biological transformations in tissue engineering.

  3. High-Q lattice mode matched structural resonances in terahertz metasurfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ningning; Zhang, Weili, E-mail: weili.zhang@okstate.edu [School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078 (United States); Singh, Ranjan, E-mail: ranjans@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2016-07-11

    The quality (Q) factor of metamaterial resonances is limited by the radiative and non-radiative losses. At terahertz frequencies, the dominant loss channel is radiative in nature since the non-radiative losses are low due to high conductivity of metals. Radiative losses could be suppressed by engineering the meta-atom structure. However, such suppression usually occurs at the fundamental resonance mode which is typically a closed mode resonance such as an inductive-capacitive resonance or a Fano resonance. Here, we report an order of magnitude enhancement in Q factor of all the structural eigenresonances of a split-ring resonator fueled by the lattice mode matching. We match the fundamental order diffractive mode to each of the odd and even eigenresonances, thus leading to a tremendous line-narrowing of all the resonances. Such precise tailoring and control of the structural resonances in a metasurface lattice could have potential applications in low-loss devices, sensing, and design of high-Q metamaterial cavities.

  4. A broadband reflective filter for applying dc biases to high-Q superconducting microwave cavities

    Science.gov (United States)

    Hao, Yu; Rouxinol, Francisco; Lahaye, Matt

    2015-03-01

    The integration of dc-bias circuitry into low-loss microwave cavities is an important technical issue for topics in many fields that include research with qubit- and cavity-coupled mechanical system, circuit QED and quantum dynamics of nonlinear systems. The applied potentials or currents serve a variety of functions such as maintaining the operating state of device or establishing tunable electrostatic interactions between devices (for example, in order to couple a nanomechanical resonator to a superconducting qubit to generate and detect quantum states of a mechanical resonator). Here we report a bias-circuit design that utilizes a broadband reflective filter to connect to a high-Q superconducting coplanar waveguide (CPW) cavity. Our design allows us to apply dc-voltages to the center trace of CPW, with negligible changes in loaded quality factors of the fundamental mode. Simulations and measurements of the filter demonstrate insertion loss greater than 20 dB in the range of 3 to 10 GHz. Transmission measurements of the voltage-biased CPW show that loaded quality factors exceeding 105 can be achieved for dc-voltages as high as V = +/- 20V for the cavity operated in the single photon regime. National Science Foundation under Grant No. DMR-1056423 and Grant No. DMR-1312421.

  5. Development of Ultra High Gradient and High Q{sub 0} Superconducting Radio Frequency Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Clemens, William A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Follkie, James E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Harris, Teena M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Kushnick, Peter W. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Machie, Danny [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Martin, Robert E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Palczewski, Ari D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Perry, Era A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Slack, Gary L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Williams, R. S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Adolphsen, C. [SLAC, Menlo Park, California, (United States); Li, Z. [SLAC, Menlo Park, California, (United States); Hao, J. K. [Peking University, Beijing (China); Li, Y. M. [Peking University, Beijing (China); Liu, K. X. [Peking University, Beijing (China)

    2013-06-01

    We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q{sub 0} superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q{sub 0} of 10{sup 10} at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q{sub 0} of 2-10{sup 10} at 2K.

  6. Design of high Q-factor metallic nanocavities using plasmonic bandgaps.

    Science.gov (United States)

    Ee, Ho-Seok; Park, Hong-Gyu; Kim, Sun-Kyung

    2016-02-10

    The surface plasmon polariton modes often excited in metallic nanocavities enable the miniaturization of photonic devices, even beyond the diffraction limit, yet their severe optical losses deteriorate device performance. This study proposes a design of metallic nanorod cavities coupled to plasmonic crystals with the aim of reducing the radiation loss of surface plasmon modes. Periodic Ag disks placed on an insulator-metal substrate open a substantial amount of plasmonic bandgaps (e.g., Δλ=290  nm at λ=1550  nm) by modifying their diameter and thickness. When an Ag nanorod with a length of ∼400  nm is surrounded by the periodic Ag disks, its Q-factor increases up to 127, yielding a 16-fold enhancement compared with a bare Ag nanorod, while its mode volume can be as small as 0.03(λ/2n)³. Ag nanorods with gradually increasing lengths exhibit high Q-factor plasmonic modes that are tunable within the plasmonic bandgap. These numerical studies on low-radiation-loss plasmonic modes excited in metallic nanocavities will promote the development of ultrasmall plasmonic devices.

  7. Moths are not silent, but whisper ultrasonic courtship songs

    DEFF Research Database (Denmark)

    Nakano, R; Takanashi, T; Fujii, T

    2009-01-01

    species of moths including members of the Noctuidae, Arctiidae, Geometridae and Crambidae. Males of nine species, 70%, produced broadband ultrasound close to females. Peak frequencies ranged from 38 to above 100 kHz. All sounds were of low intensity, 43-76 dB SPL at 1 cm [64+/-10 dB peSPL (mean +/- s......Ultrasonic hearing is widespread among moths, but very few moth species have been reported to produce ultrasounds for sexual communication. In those that do, the signals are intense and thus well matched for long distance communication. By contrast, males of the Asian corn borer moth (Crambidae......) were recently shown to whisper extremely low-intensity ultrasonic courtship songs close to females. Since low sound levels will prevent eavesdropping by predators, parasites and conspecific rivals, we predicted low intensity ultrasound communication to be widespread among moths. Here we tested 13...

  8. Commissioning and Performance Analysis of WhisperGen Stirling Engine

    Science.gov (United States)

    Pradip, Prashant Kaliram

    Stirling engine based cogeneration systems have potential to reduce energy consumption and greenhouse gas emission, due to their high cogeneration efficiency and emission control due to steady external combustion. To date, most studies on this unit have focused on performance based on both experimentation and computer models, and lack experimental data for diversified operating ranges. This thesis starts with the commissioning of a WhisperGen Stirling engine with components and instrumentation to evaluate power and thermal performance of the system. Next, a parametric study on primary engine variables, including air, diesel, and coolant flowrate and temperature were carried out to further understand their effect on engine power and efficiency. Then, this trend was validated with the thermodynamic model developed for the energy analysis of a Stirling cycle. Finally, the energy balance of the Stirling engine was compared without and with heat recovery from the engine block and the combustion chamber exhaust.

  9. Whispering--a single-subject study of glottal configuration and aerodynamics.

    Science.gov (United States)

    Sundberg, Johan; Scherer, Ronald; Hess, Markus; Müller, Frank

    2010-09-01

    Whisper productions were produced by a single adult male subject over a wide range of subglottal pressures, glottal areas, and glottal flows. Dimensional measurements were made of these three variables, including glottal perimeter. Subglottal pressure was directly obtained by a pressure transducer in a tracheal catheter, and wide-band flow with a pneumotach mask. Four types of whispers were used-hyperfunctional, hypofunctional, neutral, and postphonation-in addition to three levels of loudness (soft, medium, loud). Sequences of the /pae/ syllable were used. Video recordings of the larynx were made. The glottis was outlined by hand with extrapolation for unseen parts, and area and perimeter were obtained through image analysis software. The whisper tokens resulted in the following wide ranges: subglottal pressure: 1.3-17 cm H2O; glottal flow: 0.9-1.71 L/s; glottal area: 0.065-1.76 m2; and glottal perimeter: 1.09-6.55 cm. Hyperfunctional whisper tended to have higher subglottal pressures and lower areas and flows than hypofunctional whisper, with neutral and postphonation whisper values in between. An important finding is that glottal flow changed more for small changes of area when the area was already small, and did not create much flow change when area was changed for already larger areas; that is, whisper is "more sensitive" to airflow changes for smaller glottal areas. A general equation for whisper aerodynamics was obtained, namely, P (subglottal pressure [cm H2O])=C X F (glottal flow [cm(3)/s]), where C = 0.052 x A(4) - 0.1913 x A(3) + 0.2577 x A(2) - 0.1523 x A+0.0388, where A is the glottal area (cm(2)). Another general equation for nondimensional terms (pressure coefficient vs Reynolds number) also is offered. Implications for whisper flow resistance and aerodynamic power are given. These results give insight into whisper aerodynamics and offer equations relevant to speech synthesis. Copyright © 2010 The Voice Foundation. Published by Mosby, Inc. All

  10. InfoGallery: Informative Arts Services for Physical Library Spaces

    DEFF Research Database (Denmark)

    Grønbæk, Kaj; Rohde, Anne; Sundararajah, Balasuthas

    2006-01-01

    Much focus in digital libraries research has been devoted to new online services rather than services for the visitors in the physical library. This paper describes InfoGallery, which is a web-based infrastructure for enriching the physical library space with informative art "exhibitions" of digi......Much focus in digital libraries research has been devoted to new online services rather than services for the visitors in the physical library. This paper describes InfoGallery, which is a web-based infrastructure for enriching the physical library space with informative art "exhibitions...

  11. Photonic crystal nanofiber air-mode cavity with high Q-factor and high sensitivity for refractive index sensing

    Science.gov (United States)

    Ma, Xiaoxue; Chen, Xin; Nie, Hongrui; Yang, Daquan

    2018-01-01

    Recently, due to its superior characteristics and simple manufacture, such as small size, low loss, high sensitivity and convenience to couple, the optical fiber sensor has become one of the most promising sensors. In order to achieve the most effective realization of light propagation by changing the structure of sensors, FOM(S •Q/λres) ,which is determined by two significant variables Q-factor and sensitivity, as a trade-off parameter should be optimized to a high value. In typical sensors, a high Q can be achieved by confining the optical field in the high refractive index dielectric region to make an interaction between analytes and evanescent field of the resonant mode. However, the ignored sensitivity is relatively low with a high Q achieved, which means that the resonant wavelength shift changes non-obviously when the refractive index increases. Meanwhile, the sensitivity also leads to a less desirable FOM. Therefore, a gradient structure, which can enhance the performance of sensors by achieving high Q and high sensitivity, has been developed by Kim et al. later. Here, by introducing parabolic-tapered structure, the light field localized overlaps strongly and sufficiently with analytes. And based on a one-dimensional photonic-crystal nanofiber air-mode cavity, a creative optical fiber sensor is proposed by combining good stability and transmission characteristics of fiber and strengths of tapered structure, realizing excellent FOM {4.7 x 105 with high Q-factors (Q{106) and high sensitivities (<700 nm/RIU).

  12. Engaging Families in the Galleries Using Design Thinking

    Science.gov (United States)

    Larson, Lucy

    2017-01-01

    The Palo Alto Art Center sought a solution to the challenge that loyal family audiences, visiting weekly for art studio classes, rarely visit the contemporary art exhibition galleries. This article relates the experience of using the human-centered design process, often called Design Thinking, as the methodology to create a solution for family…

  13. An Old-Growth Definition for Western Hardwood Gallery Forests

    Science.gov (United States)

    Kelly Kindscher; Jenny Holah

    1998-01-01

    Western hardwood gallery forests are found across an extremely large, diverse geographical area that encompasses the Great Plains in the United States and Canada. Remnant forests of this type still exist in the "Prairie Peninsula," which historically projected an eastern finger into Ohio. The forests are restricted to floodplains of major rivers and are in...

  14. Inverse design of high-Q wave filters in two-dimensional phononic crystals by topology optimization.

    Science.gov (United States)

    Dong, Hao-Wen; Wang, Yue-Sheng; Zhang, Chuanzeng

    2017-04-01

    Topology optimization of a waveguide-cavity structure in phononic crystals for designing narrow band filters under the given operating frequencies is presented in this paper. We show that it is possible to obtain an ultra-high-Q filter by only optimizing the cavity topology without introducing any other coupling medium. The optimized cavity with highly symmetric resonance can be utilized as the multi-channel filter, raising filter and T-splitter. In addition, most optimized high-Q filters have the Fano resonances near the resonant frequencies. Furthermore, our filter optimization based on the waveguide and cavity, and our simple illustration of a computational approach to wave control in phononic crystals can be extended and applied to design other acoustic devices or even opto-mechanical devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Switchable microwave photonic filter between high Q bandpass filter and notch filter with flat passband based on phase modulation.

    Science.gov (United States)

    Yu, Yuan; Xu, Enming; Dong, Jianji; Zhou, Lina; Li, Xiang; Zhang, Xinliang

    2010-11-22

    We propose and demonstrate a novel switchable microwave photonic filter based on phase modulation. Both a microwave high Q bandpass filter and a microwave notch filter with flat passband are achieved respectively. And the switchability between them by tuning the two tunable optical bandpass filters is demonstrated. We also present a theoretical model and analytical expression for the proposed scheme. A frequency response of a high Q bandpass filter with a Q factor of 327 and a rejection ratio of exceeding 42 dB, and a frequency response of a notch filter with flat passband with a rejection ratio exceeding 34 dB are experimentally obtained. The operation frequency of microwave photonic filter is around 20 GHz.

  16. Realization of high-Q/V photonic crystal cavities defined by an effective Aubry-André-Harper bichromatic potential

    Science.gov (United States)

    Simbula, A.; Schatzl, M.; Zagaglia, L.; Alpeggiani, F.; Andreani, L. C.; Schäffler, F.; Fromherz, T.; Galli, M.; Gerace, D.

    2017-05-01

    We report on the realization of high-Q/V photonic crystal cavities in thin silicon membranes, with resonances around 1.55 μm wavelength. The cavity designs are based on a recently proposed photonic crystal implementation of the Aubry-André-Harper bichromatic potential, defined from the superposition of two one-dimensional lattices with a non-integer ratio between their periodicity constants. In photonic crystal nanocavities, this confinement mechanism is such that optimized figures of merit can be straightforwardly achieved, in particular an ultra-high-Q factor and diffraction-limited mode volume. Several silicon membrane photonic crystal nanocavities have been realized with measured Q-factors in the 1 × 106 range, as evidenced by resonant scattering. The generality of the proposed designs and their easy implementation and scalability make these results particularly interesting for realizing highly performing photonic nanocavities on different material platforms and operational wavelengths.

  17. A comparative analysis of whispered and normally phonated speech using an LPC-10 vocoder

    Science.gov (United States)

    Wilson, J. B.; Mosko, J. D.

    1985-12-01

    The determination of the performance of an LPC-10 vocoder in the processing of adult male and female whispered and normally phonated connected speech was the focus of this study. The LPC-10 vocoder's analysis of whispered speech compared quite favorably with similar studies which used sound spectrographic processing techniques. Shifting from phonated speech to whispered speech caused a substantial increase in the phonomic formant frequencies and formant bandwidths for both male and female speakers. The data from this study showed no evidence that the LPC-10 vocoder's ability to process voices with pitch extremes and quality extremes was limited in any significant manner. A comparison of the unprocessed natural vowel waveforms and qualities with the synthesized vowel waveforms and qualities revealed almost imperceptible differences. An LPC-10 vocoder's ability to process linguistic and dialectical suprasegmental features such as intonation, rate and stress at low bit rates should be a critical issue of concern for future research.

  18. Like-Sign Dileptons at the Fermilab Tevatron Revisited in the Light of the HERA High-$Q^2$ Anomaly

    CERN Document Server

    Choudhury, D; Choudhury, Debajyoti; Raychaudhuri, Sreerup

    1997-01-01

    We re-examine like-sign dilepton signals at the Fermilab Tevatron assuming that the excess high-$Q^2$ events recently seen at HERA are due to the production and decay of squarks of $R$-parity-violating supersymmetry. For gluinos in the mass range of 200--350 GeV, the like-sign dilepton signal can help to make the crucial distinction between the most favoured squark explanation and other proposed solutions.

  19. A minimal Beta Beam with high-Q ions to address CP violation in the leptonic sector

    CERN Document Server

    Coloma, P; Migliozzi, P; Lavina, L Scotto; Terranova, F

    2011-01-01

    In this paper we consider a Beta Beam setup that tries to leverage at most existing European facilities: i.e. a setup that takes advantage of facilities at CERN to boost high-Q ions (8Li and 8B) aiming at a far detector located at L = 732 Km in the Gran Sasso Underground Laboratory. The average neutrino energy for 8Li and 8B ions boosted at \\gamma ~ 100 is in the range E_\

  20. Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators

    Science.gov (United States)

    Kaul, Anupama B.; Epp, Larry W.; Bagge, Leif

    2011-01-01

    High Q resonators are a critical component of stable, low-noise communication systems, radar, and precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits, resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW and SAW resonators compared to their electronic counterparts. The other advantages of mechanical resonators are their inherently higher radiation tolerance, a factor that makes them attractive for NASA s extreme environment planetary missions, for example to the Jovian environments where the radiation doses are at hostile levels. Despite these advantages, both BAW and SAW resonators suffer from low resonant frequencies and they are also physically large, which precludes their integration into miniaturized electronic systems. Because there is a need to move the resonant frequency of oscillators to the order of gigahertz, new technologies and materials are being investigated that will make performance at those frequencies attainable. By moving to nanoscale structures, in this case vertically oriented, cantilevered carbon nanotubes (CNTs), that have larger aspect ratios (length/thickness) and extremely high elastic moduli, it is possible to overcome the two disadvantages of both bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Nano-electro-mechanical systems (NEMS) that utilize high aspect ratio nanomaterials exhibiting high elastic moduli (e.g., carbon-based nanomaterials) benefit from high Qs, operate at high frequency, and have small force constants that translate to high responsivity that results in improved sensitivity, lower power consumption, and im - proved tunablity. NEMS resonators have recently been demonstrated using topdown

  1. The sagrada familia: A daily whisper of the spirit

    Science.gov (United States)

    Campos, Arturo

    2002-11-01

    Sounds from the top of the Temple; songs of loyals going beyond the city, sounds of the rustic forms of the spaces for the soul; reality and miracle in just one voice, voice of religion for participation; mystery, mysticism, meditation, happiness, music and songs, bells and church towers, choirs and pulpits, religion and city. The religious architecture of Gaudi is involved by mystic sounds, real or imaginary sounds, whispers almost imperceptibles and sonorous surprises in the journeys destined to peace and spiritual calm. The Sagrada Familia in Barcelona is a Temple where the sonorous itineraries will exist and where the acoustic design of choirs, bells and bell towers was an essential idea of Antoni Gaudi. A living building with its voice singing with the people a song which will take in the whole city; ringing bells and bell towers crossing the sky and sending music, view and hearing of all the people to the new cathedral, a symbol to guide pilgrimages, ceremonies, songs and festivals. The Sagrada Familia and Barcelona, a union that Gaudi wanted to turn in total and where the acoustic design will be transformed in a daily murmur, highly spiritual. (To be presented in Spanish.)

  2. Moths are not silent, but whisper ultrasonic courtship songs.

    Science.gov (United States)

    Nakano, R; Takanashi, T; Fujii, T; Skals, N; Surlykke, A; Ishikawa, Y

    2009-12-01

    Ultrasonic hearing is widespread among moths, but very few moth species have been reported to produce ultrasounds for sexual communication. In those that do, the signals are intense and thus well matched for long distance communication. By contrast, males of the Asian corn borer moth (Crambidae) were recently shown to whisper extremely low-intensity ultrasonic courtship songs close to females. Since low sound levels will prevent eavesdropping by predators, parasites and conspecific rivals, we predicted low intensity ultrasound communication to be widespread among moths. Here we tested 13 species of moths including members of the Noctuidae, Arctiidae, Geometridae and Crambidae. Males of nine species, 70%, produced broadband ultrasound close to females. Peak frequencies ranged from 38 to above 100 kHz. All sounds were of low intensity, 43-76 dB SPL at 1 cm [64+/-10 dB peSPL (mean +/- s.d.), N=9 species]. These quiet and/or hyper-frequency ultrasounds are audible to nearby mates, but inaudible to unintended receivers. Although largely unknown because it is so inconspicuous, acoustic communication using low intensity ultrasound appears to be widespread among hearing moths. Thus, acoustic communication may be the norm rather than the exception.

  3. Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes; Zhang, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Criticality Safety Division

    2016-09-27

    Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM_Solver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) “Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.”). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the keff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

  4. Social-Level Correlates of Shooting Gallery Attendance: a focus on networks and norms

    Science.gov (United States)

    Tobin, Karin; Davey-Rothwell, Melissa; Latkin, Carl

    2011-01-01

    The purpose of this study was to examine the association between social network characteristics and peer norms related to sharing needles and shooting gallery use. Multivariate logistic regression modeling was used to identify factors that were independently associated with shooting gallery use among a sample of injection drug users recruited in Baltimore, Maryland. Of 842 study participants, 35% reported attending a shooting gallery in the past 6 months. Social networks of shooting gallery users were larger, had a greater number of injectors and crack smokers, were younger and less dense with fewer kin members compared to networks of non-gallery attenders. A greater proportion of those who used a gallery perceived that their peers shared needles and that peers would not disapprove if they used a dirty needle. Future research is needed to understand how social networks and peer norms are specific to behavioral settings and how this may impede adoption of preventive behaviors. PMID:20099016

  5. Existence and switching behavior of bright and dark Kerr solitons in whispering-gallery mode resonators with zero group-velocity dispersion

    Science.gov (United States)

    Talla Mbé, Jimmi H.; Milián, Carles; Chembo, Yanne K.

    2017-07-01

    We use the generalized Lugiato-Lefever model to investigate the phenomenon of Kerr optical frequency comb generation when group-velocity dispersion is null. In that case, the first dispersion term that plays a leading role is third-order dispersion. We show that this term is sufficient to allow for the existence of both bright and dark solitons. We identify the areas in the parameter space where both kind of solitons can be excited inside the resonator. We also unveil a phenomenon of hysteretic switching between these two types of solitons when the power of the pump laser is cyclically varied. Contribution to the Topical Issue "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  6. Ghost Whisperer's Ghost in the Machine: An example of pop cultural representation of virtual worlds

    DEFF Research Database (Denmark)

    Reinhard, CarrieLynn D.

    2009-01-01

    Analysis of an episode of the CBS series "Ghost Whisperer" for how it depicts a) what is a virtual world and b) the tensions that are involved in discussing the uses and effects of a virtual world.  Discussion focuses on the overriding negative reception of virtual worlds in popular culture due...

  7. Whisper, a resonance sounder and wave analyser: Performances and perspectives for the Cluster mission

    DEFF Research Database (Denmark)

    Decreau, P.M.E.; Fergeau, P.; KrannoselsKikh, V.

    1997-01-01

    The WHISPER sounder on the Cluster spacecraft is primarily designed to provide an absolute measurement of the total plasma density within the range 0.2-80 cm(-3). This is achieved by means of a resonance sounding technique which has already proved successful in the regions to be explored. The wav...

  8. Demonstration of suppressed phonon tunneling losses in phononic bandgap shielded membrane resonators for high-Q optomechanics

    DEFF Research Database (Denmark)

    Tsaturyan, Yeghishe; Barg, Andreas; Simonsen, Anders

    2014-01-01

    so that it assumes the form of a cm-sized bridge featuring a 1-dimensional periodic pattern, whose phononic density of states is tailored to exhibit one, or several, full band gaps around the membrane’s high-Q modes in the MHz-range. We quantify the effectiveness of this phononic bandgap shield......, which in practice usually necessitates delicate, and difficult-to-reproduce mounting solutions. Here, we demonstrate that a phononic bandgap shield integrated in the membrane’s silicon frame eliminates this dependence, by suppressing dissipation through phonon tunneling. We dry-etch the membrane’s frame...

  9. High-sensitivity and high-Q-factor glass photonic crystal cavity and its applications as sensors.

    Science.gov (United States)

    Siraji, Ashfaqul Anwar; Zhao, Yang

    2015-04-01

    We investigate the properties of a planar photonic crystal cavity on glass and its applications as sensors. An airbridged twofold defect cavity on Schott glass background and Gorilla glass substrate has been designed for high Q-factor up to 4459. The average sensitivity of the cavity resonance to background refractive index is 388 nm/Refractive Index Unit. The resonant wavelength is sensitive to background temperature by 18.5 pm/°C. The designed sensors show much higher sensitivity than those based on waveguide interferometers or photonic bandgap structures without cavity resonance. The results are also useful for experimental studies of glass photonic devices.

  10. Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating

    Directory of Open Access Journals (Sweden)

    Ming Han

    2013-07-01

    Full Text Available We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q p-phase-shifted fiber-Bragg-grating (pFBG that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong pFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched pFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit at an ambient refractive index of 1.318. The reflection spectrum of the etched pFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ~1,550 nm, corresponding to a Q-factor of 7.4 ´ 105, which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings.

  11. Connecting Universal Design for Learning with Gallery Tours in Art Museum Education

    Science.gov (United States)

    Neach, Lauren

    2017-01-01

    My research study titled, "Connecting Universal Design for Learning with Gallery Tours in Art Museum Education," establishes a relationship between gallery tours in art museum education and the principles of UDL, (CAST, 2011). Through this study I will address contemporary theories on art museum education, volunteer guide training, and…

  12. The Art Gallery/La Galeria de Arte: An Exhibition of Transformation.

    Science.gov (United States)

    Biagi, Juliet

    2001-01-01

    Describes the development of an art gallery within an urban elementary school, examining its impact on diverse students and their social interactions at school and home. The gallery had a positive impact on students (improved self-esteem, motivation, and appreciation of others); the school (transformation of the physical space and appreciation of…

  13. Inclusive Art Gallery Practices: Exploring Collaborative Processes and Pedagogy in Outreach Community Programming

    Science.gov (United States)

    Reid, Natasha

    2011-01-01

    Currently, many museums and galleries are attempting to create more welcoming and meaningful experiences for individuals who tend to be reluctant to enter and participate in these institutions. Art galleries and museums are examining and experimenting with ways to connect diverse publics through socially inclusive community outreach programs. This…

  14. Gallery productivity, emergence, and flight activity of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

    Science.gov (United States)

    M. Lake Maner; James Hanula; S. Kristine Braman

    2013-01-01

    Flight and emergence of the redbay ambrosia beetle, Xyleborus glabratus Eichhoff, were monitored from March 2011 through August 2012 using Lindgren funnel traps baited with manuka oil and emergence traps attached over individual beetle galleries on infested redbay (Persea borbonia (L.) Sprengel) trees. Of the 432 gallery entrances...

  15. Novel Gas Sensor Arrays Based on High-Q SAM-Modified Piezotransduced Single-Crystal Silicon Bulk Acoustic Resonators

    Directory of Open Access Journals (Sweden)

    Yuan Zhao

    2017-06-01

    Full Text Available This paper demonstrates a novel micro-size (120 μm × 200 μm piezoelectric gas sensor based on a piezotransduced single-crystal silicon bulk acoustic resonator (PSBAR. The PSBARs operate at 102 MHz and possess high Q values (about 2000, ensuring the stability of the measurement. A corresponding gas sensor array is fabricated by integrating three different self-assembled monolayers (SAMs modified PSBARs. The limit of detection (LOD for ethanol vapor is demonstrated to be as low as 25 ppm with a sensitivity of about 1.5 Hz/ppm. Two sets of identification code bars based on the sensitivities and the adsorption energy constants are utilized to successfully discriminate isopropanol (IPA, ethanol, hexane and heptane vapors at low and high gas partial pressures, respectively. The proposed sensor array shows the potential to form a portable electronic nose system for volatile organic compound (VOC differentiation.

  16. Fungus symbionts colonizing the galleries of the ambrosia beetle Platypus quercivorus.

    Science.gov (United States)

    Endoh, Rikiya; Suzuki, Motofumi; Okada, Gen; Takeuchi, Yuko; Futai, Kazuyoshi

    2011-07-01

    Isolations were made to determine the fungal symbionts colonizing Platypus quercivorus beetle galleries of dead or dying Quercus laurifolia, Castanopsis cuspidata, Quercus serrata, Quercus crispula, and Quercus robur. For these studies, logs from oak wilt-killed trees were collected from Kyoto Prefecture, Japan. Fungi were isolated from the: (1) entrances of beetle galleries, (2) vertical galleries, (3) lateral galleries, and (4) the larval cradle of P. quercivorus in each host tree. Among the fungus colonies which appeared on YM agar plates, 1,219 were isolated as the representative isolates for fungus species inhabiting in the galleries based on their cultural characteristics. The validity of the visual classification of the fungus colonies was checked and if necessary properly corrected using microsatellite-primed PCR fingerprints. The nucleotide sequence of the D1/D2 region of the large subunit nuclear rRNA gene detected 38 fungus species (104 strains) of which three species, i.e., Candida sp. 3, Candida kashinagacola (both yeasts), and the filamentous fungus Raffaelea quercivora were isolated from all the tree species. The two yeasts were most prevalent in the interior of galleries, regardless of host tree species, suggesting their close association with the beetle. A culture-independent method, terminal restriction fragment length polymorphism (T-RFLP) analysis was also used to characterize the fungus flora of beetle galleries. T-RFLP patterns showed that yeast species belonging to the genus Ambrosiozyma frequently occurred on the gallery walls along with the two Candida species. Ours is the first report showing the specific fungi inhabiting the galleries of a platypodid ambrosia beetle.

  17. A Near-Infrared Spectroscopy Study on Cortical Hemodynamic Responses to Normal and Whispered Speech in 3- to 7-Year-Old Children

    Science.gov (United States)

    Remijn, Gerard B.; Kikuchi, Mitsuru; Yoshimura, Yuko; Shitamichi, Kiyomi; Ueno, Sanae; Tsubokawa, Tsunehisa; Kojima, Haruyuki; Higashida, Haruhiro; Minabe, Yoshio

    2017-01-01

    Purpose: The purpose of this study was to assess cortical hemodynamic response patterns in 3- to 7-year-old children listening to two speech modes: normally vocalized and whispered speech. Understanding whispered speech requires processing of the relatively weak, noisy signal, as well as the cognitive ability to understand the speaker's reason for…

  18. Video gallery of educational lectures integrated in faculty's portal

    Directory of Open Access Journals (Sweden)

    Jaroslav Majerník

    2013-05-01

    Full Text Available This paper presents a web based educational video-clips exhibition created to share various archived lectures for medical students, health care professionals as well as for general public. The presentation of closely related topics was developed as video gallery and it is based solely on free or open source tools to be available for wide academic and/or non-commercial use. Even if the educational video records can be embedded in any websites, we preferred to use our faculty’s portal, which should be a central point to offer various multimedia educational materials. The system was integrated and tested to offer open access to infectology lectures that were captured and archived from live-streamed sessions and from videoconferences.

  19. The Cosmology Gallery: Unity through diversity in a vast and awe-inspiring universe.

    Science.gov (United States)

    Goldsmith, John

    2011-06-01

    Scientists, artists, religious and cultural leaders have come together to create the Cosmology Gallery at the Gravity Discovery Centre (GDC) located 70 km north of Perth, Western Australia. The Cosmology Gallery exhibitions include the multicultural cosmology artworks, Celestial Visions astronomical photography exhibition and the Timeline of the Universe. The multicultural cosmology artworks are new artworks inspired by Australian Indigenous, Christian, Buddhist, Islamic, Hindu, scientific and technological perspectives of the universe. The Celestial Visions exhibition features astronomical events above famous landmarks, including Stonehenge and the Pyramids. The AUD 400,000+ project was funded by Lotterywest, Western Australia and the Cosmology Gallery was officially opened in July 2008 by the Premier of Western Australia.

  20. High-Q AlAs/GaAs adiabatic micropillar cavities with submicron diameters for cQED experiments

    DEFF Research Database (Denmark)

    Lermer, M.; Gregersen, Niels; Dunzer, F.

    stringent requirements to the design and the processing of the micropillars which show a drastic decrease of the Q factor in the low diameter limit due to sidewall scattering losses and mode mismatch. Indeed, these effects limit the Q factor to ~2,000 in the submicron diameter range for a standard...... microcavity design [1, 2]. To overcome the trade-off between high Q and low Vmode, we designed and implemented a novel adiabatic AlAs/GaAs cavity design (MC1) with 3 taper segments (Fig. 1 (a)) as it was suggested by Zhang et al. for SiO2/TiO2 micropillar cavities [3]. Comparative measurements of the Q factor...... were performed between a standard one-λ microcavity structure (MC2) and MC1 for pillars with diameters ranging from 0.70 μm to 1.50 μm (Fig. 1 (b; bottom)). As can be seen in Fig. 1(b) MC1 shows significantly higher Q-factors exceeding 10.000 in the submicron diameter range due to the adiabatic cavity...

  1. Measurement of the neutral current reaction at high Q{sup 2} in the H1 experiment at HERA II

    Energy Technology Data Exchange (ETDEWEB)

    Shushkevich, Stanislav

    2012-12-15

    This thesis presents inclusive e{sup {+-}}p double and single differential cross section measurements for neutral current deep inelastic scattering of longitudinally polarized leptons on protons as a function of the negative four-momentum transfer squared Q{sup 2} and the Bjorken variable x. The data were collected in the years 2003-2007 in the H1 experiment at HERA with positively and negatively longitudinally polarized lepton beams of 27 GeV and a proton beam of 920 GeV corresponding to the centre-of-mass energy of {radical}(s)=319 GeV. The integrated luminosity is about 330 pb{sup -1}. An overview of the phenomenology of the deep inelastic scattering is given and the experimental apparatus is described. The NC cross section measurement procedure is presented and discussed in details. The measured cross sections are used to investigate electroweak effects at high Q{sup 2}. The proton structure function xF{sub 3}, sensitive to the valence quarks in the proton, is measured. The polarization effects sensitive to the chiral structure of neutral currents are investigated. The Standard Model predictions are found to be in a good agreement with the measurement.

  2. Measurement of high-Q{sup 2} neutral current cross-sections with longitudinally polarised positrons with the ZEUS detector

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Trevor P.

    2012-07-15

    The cross sections for neutral current (NC) deep inelastic scattering (DIS) in e{sup +}p collisions with a longitudinally polarised positron beam are measured at high momentum transfer squared (Q{sup 2}>185 GeV{sup 2}) at the ZEUS detector at HERA. The HERA accelerator provides e{sup {+-}}p collisions at a centre-of-mass energy of 318 GeV, which allows the weak contribution to the NC process to be studied at high Q{sup 2}. The measurements are based on a data sample with an integrated luminosity of 135.5 pb{sup -1} collected with the ZEUS detector in 2006 and 2007. The single differential NC cross sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy and the reduced cross section {sigma} are measured. The structure function xF{sub 3} is determined by combining the e{sup +}p NC reduced cross sections with the previously measured e{sup -}p measurements. The interference structure function xF{sub 3}{sup {gamma}Z} is extracted at Q{sup 2}=1500 GeV{sup 2}. The cross-section asymmetry between the positive and negative polarisation of the positron beam is measured and the parity violation effects of the electroweak interaction are observed. The predictions of the Standard Model of particle physics agree well with the measurements. (orig.)

  3. Microlasers based on high-Q rare-earth-doped aluminum oxide resonators on silicon (Conference Presentation)

    Science.gov (United States)

    Bradley, Jonathan D. B.; Su, Zhan; Frankis, Henry C.; Magden, Emir Salih; Li, Nanxi; Byrd, Matthew; Purnawirman, Purnawirman; Shah Hosseini, Ehsan; Adam, Thomas N.; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R.

    2017-02-01

    One of the key challenges in the field of silicon photonics remains the development of compact integrated light sources. In one approach, rare-earth-doped glass microtoroid and microdisk lasers have been integrated on silicon and exhibit ultra-low thresholds. However, such resonator structures are isolated on the chip surface and require an external fiber to couple light to and from the cavity. Here, we review our recent work on monolithically integrated rare-earth-doped aluminum oxide microcavity lasers on silicon. The microlasers are enabled by a novel high-Q cavity design, which includes a co-integrated silicon nitride bus waveguide and a silicon dioxide trench filled with rare-earth-doped aluminum oxide. In passive (undoped) microresonators we measure internal quality factors as high as 3.8 × 105 at 0.98 µm and 5.7 × 105 at 1.5 µm. In ytterbium, erbium, and thulium-doped microcavities with diameters ranging from 80 to 200 µm we show lasing at 1.0, 1.5 and 1.9 µm, respectively. We observe sub-milliwatt lasing thresholds, approximately 10 times lower than previously demonstrated in monolithic rare-earth-doped lasers on silicon. The entire fabrication process, which includes post-processing deposition of the gain medium, is silicon-compatible and allows for integration with other silicon-based photonic devices. Applications of such rare earth microlasers in communications and sensing and recent design enhancements will be discussed.

  4. Earth Resources Observation and Science (EROS) Center's Journey of Lewis and Clark Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the this gallery of Landsat-derived images of one of the most remarkable and productive scientific...

  5. Krasotshnõje snõ Sed Arte Gallery / Irina Butjajeva

    Index Scriptorium Estoniae

    Butjajeva, Irina

    2007-01-01

    Valgevene kunstnike Jelena Shlegeli, Vladimir Gontsharuki, Dmitri Zenkovitshi ja Dmitri Masli maalinäitus "Valgevene värvilised unenäod" Tallinna galeriis Aatrium. Näitust vahendas Sed Arte Gallery, galerist Olga Ljubaskina

  6. Voice over: Audio-visual congruency and content recall in the gallery setting

    National Research Council Canada - National Science Library

    Merle T Fairhurst; Minnie Scott; Ophelia Deroy

    2017-01-01

    ...? In the present study, we focused on an everyday situation of audio-visual learning and manipulated the relationship between audio guide tracks and viewed portraits in the galleries of the Tate Britain...

  7. PAO Image Gallery = Public Affairs Photos of EROS Projects: 1972 - 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The EROS Image Gallery collection is composed of a wide variety of images ranging from low altitude aircraft to satellite and NASA imagery; oblique photographs and...

  8. Update History of This Database - Togo Picture Gallery | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data ...List Contact us Togo Picture Gallery Update History of This Database Date Update contents 2017/05/16 Togo Pi...cs.html ) is opened. About This Database Database Description Download License Update History of This Databa...se Site Policy | Contact Us Update History of This Database - Togo Picture Gallery | LSDB Archive ...

  9. High-Q Wafer Level Package Based on Modified Tri-Layer Anodic Bonding and High Performance Getter and Its Evaluation for Micro Resonant Pressure Sensor

    National Research Council Canada - National Science Library

    Liying Wang; Xiaohui Du; Lingyun Wang; Zhanhao Xu; Chenying Zhang; Dandan Gu

    2017-01-01

    In order to achieve and maintain a high quality factor (high-Q) for the micro resonant pressure sensor, this paper presents a new wafer level package by adopting cross-layer anodic bonding technique of the glass/silicon/silica (GSS...

  10. The effect of the user's body on high-Q and low-Q planar inverted F antennas for LTE frequencies

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej

    2012-01-01

    The influence of the user's body degrades small antenna performances. This paper investigates the detuning and the losses on high-Q planar antennas for small devices due to user proximity. The results at low frequencies for the Long Term Evolution (LTE) standard are compared to the results...

  11. GPR investigations in galleries buried inside a karstified limestone formation

    Science.gov (United States)

    Rousset, D.; Sénéchal, G.; Gaffet, S.

    2009-04-01

    A large scientific program of geophysical investigations is presently performed inside the Low-Noise Underground Laboratory (Laboratoire Souterrain à Bas Bruit / LSBB, Rustrel, France) which is an decomissioned underground missile control center, buried in a karstified limestone formation. One of the goals of this project is the understanding of the water circulation inside the structure. This experimental site offers a unique opportunity of perfoming measurements within an unweathered limestone massif. The tunnel has been dug in lower cretaceous limestone which is characterized by a low clay content, high electrical resistivity. The dip is around 25 degrees and vertical faults locally affect the structure. The studied zone is located in south-eastern France (Provence) and is characterized by a mediterranean climate with long dry periods and strong, short events of rain. This phenomenon induces large variations of water content within the karstified limestone from dry to saturated conditions. Analysis of the spatial and temporal variations of the water flow in a karstified limestones needs to define the geological context and the adequate geophysical methods. GPR offers a good tradeoff between resolution and ease of use on one hand and investigation depth on the other hand. We present some GPR profiles which have been acquired in April 2008 after a quite long and strong period of rain, inducing a complete water saturation inside the karstified massif. We used several RAMAC shielded antennas from 100 to 500 MHz. The longest profile is around 600 m long, with a 20 cm spacing, running from a raw to a concrete gallery. These data sets are characterized by a very good signal to noise ratio and a signal penetration, up to 18 meters. Signal processing includes very low frequency filtering, amplitude compensation, keeping lateral relative attenuation and ringing suppression. Final sections includes migration and time to depth conversion or depth migration. The estimated

  12. Microfluidic High-Q Circular Substrate-Integrated Waveguide (SIW) Cavity for Radio Frequency (RF) Chemical Liquid Sensing.

    Science.gov (United States)

    Memon, Muhammad Usman; Lim, Sungjoon

    2018-01-06

    In this study, a high-Q circular substrate-integrated waveguide (SIW) cavity resonator is proposed as a non-contact and non-invasive radio frequency (RF) sensor for chemical sensing applications. The design of the structure utilizes SIW technology along with a circular shape to achieve a high unloaded Q factor, which is one of the important requirements for RF sensors. The resonant frequency of the proposed circular SIW cavity sensor changes when a liquid material or a chemical (microliters) is inserted in the sensitive area of the structure. The sensing of liquid materials with different permittivities is accomplished via the perturbation of the electric fields in the SIW configuration. When a microwell that is 4 mm in radius is installed vertically through the center of the bare circular SIW cavity, the operating frequency varies from 5.26 to 5.34 GHz. Similarly, when the microwell contains ethanol, the frequency shifts from 5.26 to 5.18 GHz, and the amplitude of reflection coefficient is shifted from -29 dB to -17 dB; when the microwell contains mixing deionized (DI)-water, the frequency moves from 5.26 to 4.98 GHz (which is also 0% Ethanol in our study), and the amplitude of reflection coefficient is shifted from -29 dB to -8 dB. A high unloaded Q factor is maintained throughout all experimental results. To demonstrate our idea, different concentrations of ethanol are tested and recorded. The experimental validation yields a close agreement between the simulations and the measurements.

  13. Shooting gallery attendance among IDUs in Tijuana and Ciudad Juarez, Mexico: correlates, prevention opportunities, and the role of the environment.

    Science.gov (United States)

    Philbin, Morgan; Pollini, Robin A; Ramos, Rebecca; Lozada, Remedios; Brouwer, Kimberly C; Ramos, Maria Elena; Firestone-Cruz, Michelle; Case, Patricia; Strathdee, Steffanie A

    2008-07-01

    We identified factors associated with shooting gallery attendance among injection drug users (IDUs) in two Mexico-US border cities. IDUs in Tijuana (n=222) and Ciudad Juarez (n=205), Mexico, who were >or=18 years and injected illicit drugs in the last month were recruited using respondent-driven sampling (RDS). An interviewer-administered survey collected sociodemographic and behavioral data. Logistic regression was used to examine correlates of shooting gallery attendance in each of the two cities. Homelessness and being arrested for syringe possession--both structural level factors--were associated with shooting gallery use in both cities. In Ciudad Juarez, younger age and having overdosed were also associated with shooting gallery use. Our study highlights the need for structural interventions that mitigate homelessness among IDUs and facilitate changes in law enforcement practices associated with shooting gallery use. Harm reduction interventions based within shooting galleries should also be considered to prevent transmission of blood-borne pathogens among IDUs.

  14. The Sulphate Effect on Lijiaxia Concrete Dam (China Gallery

    Directory of Open Access Journals (Sweden)

    Xufen Zhu

    2017-01-01

    Full Text Available The concrete degradation is one of the most serious problems for a dam construct during the normal operation, which determines the dam service life. Hence, it is very important to reduce the extent of the dam concrete degradation for the safety of the dam normal operation. Here, Lijiaxia hydroelectric station is taken as an example, and a comprehensive method to assess the sulphate effect on dam gallery is proposed. Eleven samples in total were taken from three difference locations by the drill bore. The microstructural investigations including X-ray fluorescence spectrometry (XRF, X-ray diffraction (XRD, scanning electron microscope (SEM, and energy dispersive spectroscopy (EDS were conducted to assess the sulphate attack and the degradation degree. Meanwhile, the water chemical analysis was applied to reveal the mechanism of concrete degradation. The experimental and analysis results indicate that the concrete degradation degree varies with the location of the samples. The components of the concrete change and the content of SO3 increase dramatically during degradation. Moreover, the mineral facies of the concrete change correspondingly, with the cement paste substituted by the calcite, calcium vitriol, and gypsum. The reinforcement and precaution measures are suggested based on the results of the degradation assessment.

  15. Conceptual Design Report. Footprint Gallery Upgrade - Civil Construction, May 1988

    Energy Technology Data Exchange (ETDEWEB)

    None

    1988-05-01

    The Footprint Gallery Complex will be enlarged and modified. The basic outline of the project will be to add 68,100 square feet of new construction, remodel 20,600 square feet of existing space, and retire by removal 17 ,500 square feet. The principal items to be addressed are: the creation of larger Main Control Rooms and Central Control Computer Rooms, the replacement of several temporary structures with permanent facilities, the provision for a growth in population of 132 people, and the creation of an intermediate sized meeting/lecture room facility. Disjointed second floor areas will be connected and made accessible to the handicapped, secure and informative viewing for visitors will be provided, and parking will be increased to match the expected growth. The new construction will provide for a more centralized concentration of systems and support personnel of the Fermilab Accelerator Division, reflecting the growth of these organizations during the last 15 years. Experiments, such as the D-Zero detector and antiproton deceleration (E760), have been assigned to the Accelerator Division for support. The associated physicists and experimenters make up the most significant component of the growth in population for which this construction will provide additional space.

  16. Whisper: Tracing the Spatiotemporal Process of Information Diffusion in Real Time.

    Science.gov (United States)

    Cao, Nan; Lin, Yu-Ru; Sun, Xiaohua; Lazer, D; Liu, Shixia; Qu, Huamin

    2012-12-01

    When and where is an idea dispersed? Social media, like Twitter, has been increasingly used for exchanging information, opinions and emotions about events that are happening across the world. Here we propose a novel visualization design, "Whisper", for tracing the process of information diffusion in social media in real time. Our design highlights three major characteristics of diffusion processes in social media: the temporal trend, social-spatial extent, and community response of a topic of interest. Such social, spatiotemporal processes are conveyed based on a sunflower metaphor whose seeds are often dispersed far away. In Whisper, we summarize the collective responses of communities on a given topic based on how tweets were retweeted by groups of users, through representing the sentiments extracted from the tweets, and tracing the pathways of retweets on a spatial hierarchical layout. We use an efficient flux line-drawing algorithm to trace multiple pathways so the temporal and spatial patterns can be identified even for a bursty event. A focused diffusion series highlights key roles such as opinion leaders in the diffusion process. We demonstrate how our design facilitates the understanding of when and where a piece of information is dispersed and what are the social responses of the crowd, for large-scale events including political campaigns and natural disasters. Initial feedback from domain experts suggests promising use for today's information consumption and dispersion in the wild.

  17. Processing of terabytes of data for seismic noise analysis with the Python codes of the Whisper Suite. (Invited)

    Science.gov (United States)

    Briand, X.; Campillo, M.; Brenguier, F.; Boue, P.; Poli, P.; Roux, P.; Takeda, T.

    2013-12-01

    The Whisper Suite, as part of the ERC project Whisper (whisper.obs.ujf-grenoble.fr), is developed with the high-level programming language Python and uses intensively the scientific libraries Scipy and Obspy, which is dedicated to the seismological community (www.obspy.org). The Whisper Suite consists of several tools. It provides a flexible way to specify a pipeline of seismogram processing. The user can define his own sequence of treatments, can use the Python libraries he needs and eventually, can add his processing procedure to the Whisper Suite. Another package is dedicated to the computation of correlations. When dealing with large data set, computational time becomes a major difficulty and we devoted a lot of efforts to make possible the fast processing of the large data sets produced by the present day dense seismic networks. With the Whisper Suite, we manage currently more than 150TB of data for ambient noise analysis. For the computations of 68 millions correlations (daily, 5Hz, correlation window 3600s) on a 50 core cluster, with a dedicated disk array, the required time is 4 days. With a distributed storage (Irods) and a grid of clusters (mode best effort), both provided by the University of Grenoble, we compute currently one year of 4-hours correlations for 550 3C stations of the Hi-Net Japanese Network in one day (about 350 millions individual correlations) . Note that the quadratic space complexity can be critical. We developed also codes for the analysis of the correlations. The Whisper Suite is used to make challenging observations using cross-correlation techniques at various scales in the Earth. We present some examples of applications. Using a global data set of available broadband stations, we discuss the emergence of the complete teleseismic body wave wave field, including the deep phases used for imaging of the mantle and the core. The giant 2011 Tohoku-oki earthquake and the records of the dense Hi-Net array offer an opportunity to analyze

  18. Volcano monitoring with a multiparametric station placed inside a subhorizontal gallery in Tenerife (Canary Islands)

    Science.gov (United States)

    Torres-González, Pedro; Moure-García, David; Luengo-Oroz, Natividad; Jiménez-Mejías, María; Jiménez-Abizanda, Ana Isabel; García-Fraga, Jose Manuel; Soler-Javaloyes, Vicente; Domínguez Cerdeña, Itahiza

    2017-04-01

    Measuring gaseous emissions from a volcano is one of the main tasks in volcano monitoring. These emissions can occur inside an active crater as fumaroles or plumes or along the whole volcanic area as diffuse emissions through porous soils or using preferential paths like dikes, faults or fractures. H2O, CO2, SO2 and H2S are the main species released by volcanoes. Among them, CO2 has received special attention in the last years. It has been used as an unrest and/or eruption early warning signal due to his low magma solubility and easily measurement. In the Canary Islands (oceanic volcanic islands) during the last century hundreds of galleries, subhorizontal drillings with lengths from few meters to kilometers and a 2x2 meters mean section, have been drilled to obtain groundwater. In the island of Tenerife there are about 1200. These infrastructures can cut across some preferential rising paths like dikes or fractures, so they turn to be optimum places to measure volcanic gas emissions. In addition, atmospheric parameters influence significantly decreases inside the galleries. In this work, we present data analysis from a three years registration period of a station placed at 1600 meters from the entrance of a gallery in Tenerife. This station measures several parameters like ambient and soil temperature and CO2 and Radon air concentrations inside the gallery. We also show how outside atmospheric parameters affect the microclimate inside the gallery.

  19. Seasonal feeding ecology of ring-tailed lemurs: a comparison of spiny and gallery forest habitats.

    Science.gov (United States)

    LaFleur, Marni; Sauther, Michelle L

    2015-01-01

    Although Lemur catta persists in many habitat types in southern Madagascar, its ecology has been primarily studied within gallery forests. We compare plant food selection and properties for ring-tailed lemurs in the spiny and gallery forests over the synchronized lactation period (September to March) that includes both the dry and wet seasons. We found no significant habitat-specific differences in the type of plant part consumed per month (i.e. flower, fruit, leaf) or between the intake of soluble carbohydrates. However, the presence and use of Tamarindus indica plants appear to elevate protein and fiber intake in the gallery forest lemurs' diets. Protein is especially important for reproductive females who incur the added metabolic costs associated with lactation; however, fiber can disrupt protein digestion. Future work should continue to investigate how variations of protein and fiber affect ring-tailed lemur dietary choice and nutrient acquisition. © 2015 S. Karger AG, Basel.

  20. Topological Galleries: A High Level User Interface for Topology Controlled Volume Rendering

    Energy Technology Data Exchange (ETDEWEB)

    MacCarthy, Brian; Carr, Hamish; Weber, Gunther H.

    2011-06-30

    Existing topological interfaces to volume rendering are limited by their reliance on sophisticated knowledge of topology by the user. We extend previous work by describing topological galleries, an interface for novice users that is based on the design galleries approach. We report three contributions: an interface based on hierarchical thumbnail galleries to display the containment relationships between topologically identifiable features, the use of the pruning hierarchy instead of branch decomposition for contour tree simplification, and drag-and-drop transfer function assignment for individual components. Initial results suggest that this approach suffers from limitations due to rapid drop-off of feature size in the pruning hierarchy. We explore these limitations by providing statistics of feature size as function of depth in the pruning hierarchy of the contour tree.

  1. Theorizing How Art Gallery Interventions Impact People With Dementia and Their Caregivers.

    Science.gov (United States)

    Camic, Paul M; Baker, Erin L; Tischler, Victoria

    2016-12-01

    Dementia refers to a variety of diseases that are characterized by cognitive difficulties and an overall decline in daily living skills. Psychologically informed arts and health programs may be particularly beneficial ways of improving the lives of people with dementia and their caregivers. This study sought to better understand how programs at contemporary and traditional art galleries might play a role in the lives of people with dementia. Participants included 12 people with mild-to-moderate dementia, their 12 caregivers and 4 gallery facilitators. Those with dementia and their caregivers were engaged in art viewing followed by art making over an 8-week period. Data, collected through postintervention interviews with participants, field notes and extensive written communication between the facilitators and research team, were analyzed using grounded theory methodology to theorize how gallery-based interventions affect people with dementia and those who care for them. The emerging theory has four primary components: the art gallery is seen as being a physically valued place that provides intellectual stimulation and offers opportunities for social inclusion that can change how dementia is perceived. These components coalesced to create positive emotional and relational effects for those with dementia and caregivers. The resulting theory has potential implications for the use of gallery-based programs in dementia care within public health, healthcare, and museum/art gallery policy and practice. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Viability of microcomputed tomography to study tropical marine worm galleries in humid muddy sediments

    Energy Technology Data Exchange (ETDEWEB)

    Pennafirme, Simone F., E-mail: sipennafirme@gmail.com [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Marinha; Machado, Alessandra S.; Lima, Inaya; Suzuki, Katia N.; Lopes, Ricardo T., E-mail: machado@lin.ufrj.br, E-mail: inaya@lin.ufrj.br, E-mail: norisuzuki6@yahoo.com.br, E-mail: ricardo@lin.ufj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear

    2013-07-01

    Bioturbation is an ecological process driven by organisms, which transports nutrients and gases from air/water to sediment through their galleries, by the time they feed, burrow and/or construct galleries. This exchange is vital to the maintenance of micro and macrobenthic organisms, mainly in muddy flat environments. Species with distinct galleries could create levels of bioturbation, affecting the benthic interactions. In this sense, it is fundamental developing a non-destructive method that permits identifying/quantifying the properties of these galleries. The recent advances in micro-computed tomography are allowing the high resolution 3D images generation. However, once muddy sediments are rich in organic matter and interstitial water, these would lead to motion artifacts which could, in turn, decrease the accuracy of galleries identification/quantification. In this context, the aim of this study was to develop a protocol which combines laboratory experiments and microtomography analysis in order to generate accurate 3D images of the small marine worm's galleries within humid muddy sediments. The sediment was collected at both muddy flats of Surui's and Itaipu lagoon's mangroves (RJ-Brazil), sieved (0.5mm mesh) and introduced with one individual of the marine worm Laeonereis acuta (Nereididae, Polychaeta) in each acrylic corer holders (4.4cm of internal diameter). High energy microtomography scanner was used to obtain 3D images and the setup calibration was 130 kV and 61 mA. Each acquisition image time was among 4h and 6h. Several procedures of drying remained water inside the cores were performed aiming obtaining images without movement artifacts due to circulating water, and this issue was one of the main studied parameter. In order to investigate possible chemical effects, 2ml of formalin (35%) with menthol were added to the surface of the cores. The results show that although the drying time was appropriated, the chemicals created bubbles

  3. 75 FR 15740 - Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of Investigation

    Science.gov (United States)

    2010-03-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of... Leather Company, Inc., Trenton, Maine. The petitioner has requested that the petition be withdrawn...

  4. Fra Bartolomeo della Porta detto Fra Bartolomeo, Adorazione del Bambino, National Gallery, London

    DEFF Research Database (Denmark)

    Fischer, Chris

    2014-01-01

    En artikel om et maleri af Fra Bartolomeo i National Gallery i London udlånt til en udstilling i Museo Tosio Martinengo I Brescia i forbindelse med opdagelsen af et fuldstændigt overensstemmende maleri i dette museums magasiner. Hypotesen var at Bresciabilledet var et værkstedsarbejde lavet på...

  5. License - Togo Picture Gallery | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available liance with the terms and conditions of the license described below. The license sp...List Contact us Togo Picture Gallery License License to Use This Database Last updated : 2017/05/16 You may use this database in comp

  6. Experiences from a Real-Time Mobile Collaborative Writing System in an Art Gallery

    DEFF Research Database (Denmark)

    Korn, Matthias; Polli, Anna Maria; Klokmose, Clemens Nylandsted

    We present first experiences from Local Area Artworks, a system enabling collaborative art interpretation on-site, deployed during an exhibition in a local art gallery. Through the system, we explore ways to re-connect people to local places by making use of their personal mobile devices as inter...... of small groups of strangers or acquaintances experiencing the exhibition together....

  7. Domus: An On-Gallery Digital Museum Experience in Two Parts

    NARCIS (Netherlands)

    van der Vaart, M.; Ray, C.A.; Gottlieb, H.; Szeląg, M.

    2014-01-01

    In September 2014, the Allard Pierson Museum, the archaeology museum of the University of Amsterdam, opened its new Roman gallery. Leading to the redevelopment, the Museum’s NewMediaLab explored how interactive technologies, particularly virtual re-contextualization, could be used to aid visitor

  8. Durability of visitable concrete sewer gallery under the effect of domestic wastewater

    Science.gov (United States)

    Salhi, Aimed; Kriker, Abdelouahed; Tioua, Tahar; Abimiloud, Youcef; Barluenga, Gonzalo

    2016-07-01

    The durability of concrete structures for the disposal of wastewater depends on their behavior when faced to different aggressions such as mechanics, chemical and biological, causing a deterioration often cementing matrix. The deterioration of recent evacuations wastewater infrastructure, made of reinforced concrete less than 15 years ago, has become an important concern. The aim of this study was to investigate the degradation and the factors responsible for the deterioration of the concrete visitable gallery of sewage from the town of Touggourt (south-east of Algeria). Thus, samples from different parts of the gallery were extracted and unaltered samples were selected as a reference. A degraded sample exposed to H2S gas and another sample of the gallery submerged into wastewater were analyzed to characterize the internal and external damage to the gallery as well as the chemical and mineralogical changes. These tests were complemented by a physical and mechanical characterization of the samples. The experimental results showed the strong anisotropy of both internal and external damage.

  9. High sensitivity and high Q-factor nanoslotted parallel quadrabeam photonic crystal cavity for real-time and label-free sensing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Daquan [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Kita, Shota; Wang, Cheng; Lončar, Marko [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Liang, Feng; Quan, Qimin [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); Tian, Huiping; Ji, Yuefeng [State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-08-11

    We experimentally demonstrate a label-free sensor based on nanoslotted parallel quadrabeam photonic crystal cavity (NPQC). The NPQC possesses both high sensitivity and high Q-factor. We achieved sensitivity (S) of 451 nm/refractive index unit and Q-factor >7000 in water at telecom wavelength range, featuring a sensor figure of merit >2000, an order of magnitude improvement over the previous photonic crystal sensors. In addition, we measured the streptavidin-biotin binding affinity and detected 10 ag/mL concentrated streptavidin in the phosphate buffered saline solution.

  10. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Teleportation of Entangled States through Divorce of Entangled Pair Mediated by a Weak Coherent Field in a High-Q Cavity

    Science.gov (United States)

    Cardoso B., W.; Almeida G. de, N.

    2008-07-01

    We propose a scheme to partially teleport an unknown entangled atomic state. A high-Q cavity, supporting one mode of a weak coherent state, is needed to accomplish this process. By partial teleportation we mean that teleportation will occur by changing one of the partners of the entangled state to be teleported. The entangled state to be teleported is composed by one pair of particles, we called this surprising characteristic of maintaining the entanglement, even when one of the particle of the entangled pair being teleported is changed, of divorce of entangled states.

  11. Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

    Directory of Open Access Journals (Sweden)

    P. Canu

    Full Text Available We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth’s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.

    Key words. Space plasma physics (active perturbation experiments; waves and instabilities; instrument and techniques

  12. Whispering wind

    DEFF Research Database (Denmark)

    Barlieb, Christophe; Richter, Christoph; Greschner, Björn

    2009-01-01

    Low frequency noise generated by aircraft during pre-takeoff, takeoff, landing and post-landing operations equates to high levels of undesirable ground noise pollution. This phenomenon is gaining heightened popular interest among air transportation specialists and agencies as urban settlements an...

  13. [The gallery forests of the São Francisco river as corridors for Euglossine bees (Hymenoptera: Apidae) from tropical rainforests].

    Science.gov (United States)

    Moura, Debora C; Schlindwein, Clemens

    2009-01-01

    Euglossini are typical bees of Neotropical rainforests and only a few species occur in the Caatinga. The São Francisco river, which is the only permanent river in the semi-arid NE-Brazil, is bordered by a gallery forest with evergreen leaves. This environment offers flooral rewards along the year. Surveys of euglossine bees by attracting males to scent baits showed that species of the Atlantic Rainforest like Euglossa imperialis Cockerel, E. truncata Moure and Eulaema cingulata Fabricius occur in the gallery forest of the São Francisco river under the semi-arid climate of the caatinga region. These bees are restricted to the gallery forests which function as bio-corridors, and are absent at places where the forests were cut down. This emphasizes the need to protect the threatened gallery forests to maintain biodiversity.

  14. Investigations on gallery patterns of the Almond bark bettle (Scolytus amygdali Guerin-Méneville, 1847 (Coleoptera, Curculionidae in Tunisia

    Directory of Open Access Journals (Sweden)

    Asma Zeiri

    2016-01-01

    Full Text Available The Almond bark beetle Scolytus amygdali Guerin-Meneville, 1847 is a serious beetle that can affect important economic crops in Tunisia. The species is morphologically similar to other bark beetles attacking fruit trees such as Scolytus mediterraneus. The gallery systems of both species are also generally hard to differentiate. A detailed study about gallery systems has carried out in the central region of Tunisia in order to give more details on beetle damage under the bark. Maternal and larval galleries from infested branches of almond were examined and measured. It is hoped that these details of the shape and measurements of the gallery systems of Scolytus amygdali will facilitate the identification of infestations of almond bark beetles attacking fruit trees in Tunisia.

  15. Strong coupling of hybrid and plasmonic resonances in liquid core plasmonic micro-bubble cavities.

    Science.gov (United States)

    Lu, Qijing; Li, Ming; Liao, Jie; Liu, Sheng; Wu, Xiang; Liu, Liying; Xu, Lei

    2015-12-15

    A thin-wall plasmonic micro-bubble resonator, which is a high-Q optofluidic silica bubble cavity with a thin Ag film on the inside wall of the bubble, is proposed and fabricated to manipulate coupling among various types of resonant modes by changing its wall thickness and refractive index of the liquid in the core. Coupling of high-Q whispering gallery mode/plasmonic resonant mode forms hybrid mode; the hybrid mode can again strongly couple with another interior plasmonic resonant mode in the bubble cavity to achieve tunable high-Q plasmonic resonance that can be feasibly accessed by standard tapered fiber coupling. Therefore, the novel cavity structure provides a unique, yet general, platform to study plasmonic/photonic, hybrid/plasmonic, and plasmonic/plasmonic coupling.

  16. [Diversity of filamentous fungi associated with Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) and its galleries in berries of Coffea canephora (Pierre)].

    Science.gov (United States)

    Gama, Farah de C; Teixeira, César A D; Garcia, Alvanir; Costa, José N M; Lima, Daniela K S

    2006-01-01

    Field sampling was carried out in Ouro Preto d'Oeste - Rondônia (10 degrees 45'S and 62 degrees 15'W) to evaluate the mycobiota associated with Hypothenemus hampei Ferrari [cuticle, mouth, prothorax (mycangia), gut and feces] and its galleries on berries of Coffea canephora Pierre. Ten genera (201 isolates) were directly related with the insect while five genera (20 isolates) were related with galleries on berries. All the genera identified in the insects were also present in their galleries, what indicates that boring may be an active way of fungi inoculation by H. hampei. The fungi genera were more diverse in the mouth and prothorax of borers, and lower in feces. Fusarium, Penicillium and Geotrichum, with abundance of 55.7, 24.3 and 10.8%, respectively, were dominant genera. In the galleries Fusarium, Geotrichum, Trichoderma and Aspergillus with abundance of 33.3, 29.6, 18.5 and 14.8%, respectively, were dominant genera. The overall presence of Fusarium in coffee berry borer and its galleries) reinforces previous indications of a close interaction between H. hampei-Fusarium. The presence of Aspergillus and Penicillium emphasizes the possibility of "ochratoxin dispersion" by the borer. This work provides the first record of the mycobiota associated with H. hampei in C. canephora. Among the identified genera, Cephalosporium, Geotrichum and Oidiodendrum were recorded for the first time in association with H. hampei and its galleries in C. canephora.

  17. Shooting Gallery Attendance among IDUs in Tijuana and Ciudad Juarez, Mexico: Correlates, Prevention Opportunities, and the Role of the Environment

    Science.gov (United States)

    Philbin, Morgan; Pollini, Robin A.; Ramos, Rebecca; Lozada, Remedios; Brouwer, Kimberly C.; Ramos, Maria Elena; Firestone-Cruz, Michelle; Case, Patricia; Strathdee, Steffanie A.

    2009-01-01

    We identified factors associated with shooting gallery attendance among injection drug users (IDUs) in two Mexico–US border cities. IDUs in Tijuana (n = 222) and Ciudad Juarez (n = 205), Mexico, who were ≥18 years and injected illicit drugs in the last month were recruited using respondent-driven sampling (RDS). An interviewer-administered survey collected sociodemographic and behavioral data. Logistic regression was used to examine correlates of shooting gallery attendance in each of the two cities. Homelessness and being arrested for syringe possession—both structural level factors—were associated with shooting gallery use in both cities. In Ciudad Juarez, younger age and having overdosed were also associated with shooting gallery use. Our study highlights the need for structural interventions that mitigate homelessness among IDUs and facilitate changes in law enforcement practices associated with shooting gallery use. Harm reduction interventions based within shooting galleries should also be considered to prevent transmission of blood-borne pathogens among IDUs. PMID:18369723

  18. Effects of gallery density and species ratio on the fitness and fecundity of two sympatric bark beetles (Coleoptera: Curculionidae).

    Science.gov (United States)

    Davis, T S; Hofstetter, R W

    2009-06-01

    Interspecific interactions among tree-killing bark beetle species may have ecologically important consequences on beetle population dynamics. Using two tree-killing beetle species (Dendroctonus brevicomis and D. frontalis), we performed observational and experimental studies to verify cross-attraction and co-colonization under field conditions in northern Arizona and test the effects of gallery density and species ratio on response variables of average gallery length, offspring size (progeny fitness), and offspring production per centimeter gallery (fecundity). Our results show that both D. frontalis and D. brevicomis aggregate to pheromones synthesized de novo by D. brevicomis under field conditions and that galleries of both D. brevicomis and D. frontalis occurred together in the same region of a single host tree with significant frequency. In experimental manipulations of species ratios, the presence of conspecific beetles in the gallery environment strongly mediated fecundity, but D. frontalis was the only species that suffered negative impacts from the presence of heterospecific beetles in the gallery environment. Interactions did not result in any apparent fitness effects for progeny of either species, which suggests that multispecies aggregations and co-colonization may be a dominant ecological strategy in the region and result in niche sharing.

  19. High-Q Wafer Level Package Based on Modified Tri-Layer Anodic Bonding and High Performance Getter and Its Evaluation for Micro Resonant Pressure Sensor

    Directory of Open Access Journals (Sweden)

    Liying Wang

    2017-03-01

    Full Text Available In order to achieve and maintain a high quality factor (high-Q for the micro resonant pressure sensor, this paper presents a new wafer level package by adopting cross-layer anodic bonding technique of the glass/silicon/silica (GSS stackable structure and integrated Ti getter. A double-layer structure similar to a silicon-on-insulator (SOI wafer is formed after the resonant layer and the pressure-sensitive layer are bonded by silicon direct bonding (SDB. In order to form good bonding quality between the pressure-sensitive layer and the glass cap layer, the cross-layer anodic bonding technique is proposed for vacuum package by sputtering Aluminum (Al on the combination wafer of the pressure-sensitive layer and the resonant layer to achieve electrical interconnection. The model and the bonding effect of this technique are discussed. In addition, in order to enhance the performance of titanium (Ti getter, the prepared and activation parameters of Ti getter under different sputtering conditions are optimized and discussed. Based on the optimized results, the Ti getter (thickness of 300 nm to 500 nm is also deposited on the inside of the glass groove by magnetron sputtering to maintain stable quality factor (Q. The Q test of the built testing system shows that the number of resonators with a Q value of more than 10,000 accounts for more than 73% of the total. With an interval of 1.5 years, the Q value of the samples remains almost constant. It proves the proposed cross-layer anodic bonding and getter technique can realize high-Q resonant structure for long-term stable operation.

  20. Arts university student mentors and gallery peer leaders: partnerships for learning

    OpenAIRE

    Butcher, John

    2010-01-01

    This case study describes a partnership between University College Falmouth (UCF) and Tate St. Ives (TSI). Framed within a national Enquire project (one strand of a DCMS funded commissioning programme) investigating the learning benefits of gallery education, the report tells the story of a successful collaboration which engaged undergraduate Art student mentors from UCF in a peer leadership project at TSI. The project was evaluated using an innovative action research model to explore peer le...

  1. Perancangan E-Commerce Pada Febrin Fashion Gallery Berbasis Web Application

    OpenAIRE

    Manalu, Febrin Yessy

    2017-01-01

    142406018 Perkembangan teknologi informasi dan komunikasi pada saat ini mempunyai peranan yang sangat penting dalam kehidupan. Dimana tuntutan masyarakat akan kebutuhan teknologi semakin lama semakin besar khususnya pada sektor perdagangan. Untuk itu pada penulisan tugas akhir ini, penulis membuat suatu website pada Colors Fashion Gallery. Website ini di kembangkan dengan menggunakan perangkat lunak Sublime Text 2.0.2, Apache 2.2.3, PHP 5.2, dan MySQL 5.0, Website ini berfungsi untuk membe...

  2. Nonstandard FDTD Simulation-Based Design of CROW Wavelength Splitters

    Directory of Open Access Journals (Sweden)

    Naoki Okada

    2011-01-01

    Full Text Available The finite-difference time-domain (FDTD algorithm has been used in simulation-based designs of many optical devices, but it fails to reproduce high-Q whispering gallery modes (WGMs. On the other hand, the nonstandard (NS FDTD algorithm can accurately compute WGMs and can be used to make simulation-based designs of WGM devices. Wavelength splitters using the coupled resonator optical waveguides (CROWs based on WGM couplings have recently attracted attention because they are potentially ultracompact. In this paper, we design a CROW wavelength splitter using NS FDTD simulations and demonstrate high interchannel extinction ratios of over 20 dB.

  3. Plasmonic Nanoparticle-based Protein Detection by Optical Shift of a Resonant Microcavity

    CERN Document Server

    Santiago-Cordoba, Miguel A; Vollmer, Frank; Demirel, Melik C

    2011-01-01

    We demonstrated a biosensing approach which, for the first time, combines the high-sensitivity of whispering gallery modes (WGM) with a metallic nanoparticle based assay. We provided a computational model based on generalized Mie theory to explain the higher sensitivity of protein detection through Plasmonic enhancement. We quantitatively analyzed the binding of a model protein (i.e., BSA) to gold nanoparticles from high-Q WGM resonance frequency shifts, and fit the results to an adsorption isotherm, which agrees with the theoretical predictions of a two-component adsorption model.

  4. High Diversity and Low Specificity of Chaetothyrialean Fungi in Carton Galleries in a Neotropical Ant–Plant Association

    Science.gov (United States)

    Nepel, Maximilian; Voglmayr, Hermann; Schönenberger, Jürg; Mayer, Veronika E.

    2014-01-01

    New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the – usually undescribed – fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes). Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae), the ant Azteca brevis (Formicidae: Dolichoderinae) and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant–fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU) was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis. PMID:25398091

  5. High diversity and low specificity of chaetothyrialean fungi in carton galleries in a neotropical ant-plant association.

    Directory of Open Access Journals (Sweden)

    Maximilian Nepel

    Full Text Available New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the - usually undescribed - fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes. Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae, the ant Azteca brevis (Formicidae: Dolichoderinae and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

  6. Ephemeral Transparency: Glass as a Reflective Screen and Opaque Veil in the New National Gallery

    Directory of Open Access Journals (Sweden)

    Deniz Balik

    2017-12-01

    Full Text Available This article evaluates the dilemma between intentions and outcomes, based on the transparency debate that has recently resurfaced, by undertaking a critical reading of essential architectural history texts. Using the New National Gallery by Ludwig Mies van der Rohe, in Berlin, as the central focus, it argues that, in reality, transparent buildings do not always allow clear vision, free flow, circulation, connection, and accessibility. As a result, the building challenges modern notions by presenting glass as an ephemeral and temporal reflective screen and a condensed opaque veil due to its context and content.

  7. Orchid bee (Hymenoptera: Apidae community from a gallery forest in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    Francinaldo S Silva

    2012-06-01

    Full Text Available The orchid bees are a very important group of pollinators distributed in the Neotropics. Although a lot of studies concerning male euglossine bees have been done in this region, few works have so far been carried out in the Cerrado biome. This manuscript has the main objective to present the orchid bee community from a Gallery Forest in the Northeastern Brazilian Cerrado landscape, taking account the species composition, abundance, seasonality and hourly distribution. Male euglossine bees were collected monthly from October 2007 to May 2009, in the Reserva Florestal da Itamacaoca belonging to the Companhia de Água e Esgoto do Maranhão, in Chapadinha municipality, Maranhão State. The scents eucalyptol, eugenol and vanillin were utilized, between 07:00 and 17:00hr, to attract the euglossine males. Cotton balls were dampened with the scents and suspended by a string on tree branches 1.5m above soil level, set 8m from one another. The specimens were captured with entomological nets, killed with ethyl acetate and transported to the laboratory to be identified. A total of 158 individuals and 14 species of bees were recorded. The genus Eulaema was the most representative group of euglossine bees in relation to the total number of the sampled individuals, accounting for 50.6% of bees followed by Euglossa (26.6%, Eufriesea (15.2% and Exaerete (7.6%. The most frequent species were Eulaema nigrita (27.8%, Eulaema cingulata (19% and Euglossa cordata (18.3%. Many species typical of forested environments were found in samples, like Euglossa avicula, Euglossa violaceifrons and Eulaema meriana, emphasizing the role played by the Gallery Forests as bridge sites to connect the two great biomes of Amazonia and Atlantic Forest. The occurrence of Exaerete guaykuru represents the second record of this species for the Neotropical region, and both records coming from the Gallery Forest zones. The male euglossine bees were sampled mainly in the dry season, where 62

  8. Moving the body painting into the art gallery — knowing about and appreciating works of Aboriginal art

    Directory of Open Access Journals (Sweden)

    Howard Morphy

    2011-06-01

    Full Text Available The paper focuses on two kinds of relationship: between Western fine art and Indigenous art, and between anthropological and art historical approaches to understanding and appreciating works of art. The primary focus is on the process by which Australian Aboriginal art came to be incorporated within galleries of fine art. This process brought both kinds of relationships to the fore in the contemporary context and challenged established boundaries exemplified by the distinction between the museum and the art gallery. It is argued that objects encompassed within the category of fine art come from very different cultural traditions and historical backgrounds. The methods of both art history and anthropology can be productively applied in analysing the forms and significance of artworks in their social and cultural contexts. The paper concludes by considering some of the implications of the co-presence of artworks from different cultural traditions in the same contemporary gallery spaces.

  9. PHYTOSSOCIOLOGY AND DIAMETRIC ESTRUCTURE IN THE GALLERY FOREST OF PITOCO, IN THE ECOLOGICAL RESERVE OF IBGE, DF

    Directory of Open Access Journals (Sweden)

    Manoel Cláudio da Silva Júnior

    2005-06-01

    Full Text Available The gallery forest, in the cerrado region, has a very important function on the environmental and social equilibrium.Despite been protected by law, gallery forests have been systematically replaced by agriculture and other regional uses. One thousandtrees (DAP 5cm were sampled using point centered-quarter (PCQ method. Sampling lines were established, from the head to themouth of the stream and from the stream margins to the forest-cerrado border, of the Pitoco gallery forest, in the IBGE EcologicalReserve, in Federal District, Brazil. Results showed 99 species of 46 families in the area. The most important families were:Leguminosae, Vochysiaceae, Rubiaceae, Anacardiaceae, Euphorbiaceae, Lauraceae, Burseraceae, Moraceae, Annonaceae eSymplocaceae, while the most important species were: Callisthene major, Tapirira guianensis, Protium almecega, Copaifera langsdorffii,Sclerolobium paniculatum var. rubiginosum, Pseudolmedia guaranítica, Faramea cyanea, Emmotum nitens, Lamanonia ternata,Maprounea guianensis, excluding the group of dead trees which was ranked in the 5th position. Density and basal area were estimatedas 1971 trees.ha-1 and 38,8 m².ha-1 ,respectively. Diameter distribution showed a tendency to an inverted J curve revealing low levelsof disturbance in this gallery forest. A floristic comparison carried out with 21 gallery forests in the Federal District indicated Pitocogallery forest as a rich site including 99 (26,2% of the total of 378 species recorded, a Shannon & Weaver diversity index estimatedas 3,86 nats.ind-1 and Sørensen similarities ranging from 0,29 to 0,80 with DF gallery forests.

  10. The response of bats (Mammalia: Chiroptera) to an incidental fire on a gallery forest at a Neotropical savanna

    OpenAIRE

    de Oliveira, Hernani F. M.; Aguiar, Ludmilla M. S.

    2015-01-01

    Fire is a common and natural event in Cerrado that can influence the composition of trees and mammals and change the entire conditions of the environment. This study was developed in a gallery forest of Distrito Federal - Brazil. Bat samplings were conducted for a total of six nights after a fire that happened on the gallery forest. Three samplings were conducted: one day, three months and seven months after fire. A total of nine mist nets (12 m x 3 m) were opened from 7pm to 1am. Captured ba...

  11. A High-Q Resonant Pressure Microsensor with Through-Glass Electrical Interconnections Based on Wafer-Level MEMS Vacuum Packaging

    Directory of Open Access Journals (Sweden)

    Zhenyu Luo

    2014-12-01

    Full Text Available This paper presents a high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging. An approach to maintaining high-vacuum conditions by integrating the MEMS fabrication process with getter material preparation is presented in this paper. In this device, the pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in “H” type doubly-clamped micro resonant beams, leading to a resonance frequency shift. The device geometries were optimized using FEM simulation and a 4-inch SOI wafer was used for device fabrication, which required only three photolithographic steps. In the device fabrication, a non-evaporable metal thin film as the getter material was sputtered on a Pyrex 7740 glass wafer, which was then anodically bonded to the patterned SOI wafer for vacuum packaging. Through-glass via holes predefined in the glass wafer functioned as the electrical interconnections between the patterned SOI wafer and the surrounding electrical components. Experimental results recorded that the Q-factor of the resonant beam was beyond 22,000, with a differential sensitivity of 89.86 Hz/kPa, a device resolution of 10 Pa and a nonlinearity of 0.02% F.S with the pressure varying from 50 kPa to 100 kPa. In addition, the temperature drift coefficient was less than −0.01% F.S/°C in the range of −40 °C to 70 °C, the long-term stability error was quantified as 0.01% F.S over a 5-month period and the accuracy of the microsensor was better than 0.01% F.S.

  12. The F1-F2 vowel chart for Czech whispered vowels a, e, i, o, u.

    Science.gov (United States)

    Grepl, Michal; Furst, Tomas; Pesak, Josef

    2007-12-01

    The aim of this contribution is to present the formant chart of the Czech vowels a, e, i, o, u and show that this can be achieved by means of digital methods of sound processing. A group of 35 Czech students of the Pedagogical Faculty of Palacky University was tested and a record of whispered vowels was taken from each of them. The record was digitalized and processed by the Discrete Fourier Trasform. The result is the power spectrum of the individual vocals - the graphic output consists of a plot of the relative power of individual frequencies in the original sound. The values of the first two maxima which represent the first and the second formants were determined from the graph. The values were plotted on a formant chart. Altogether, 175 spectral analyses of individual vowels were performed. In the resulting power spectrum, the first and the second formant frequencies were identified. The first formant was plotted against the second one and pure vocal formant regions were identified. Frequency bands for the Czech vowel "a" were circumscribed between 850 and 1150 Hz for first formant (F1) and between 1200 and 2000 Hz for second formant (F2). Similarly, borders of frequency band for vowel "e" they were 700 and 950 Hz for F1 and 1700 and 3000 Hz for F2. For vowel "i" 300 and 450 Hz for F1 and 2000 and 3600 Hz for F2, for vowel "o" 600 and 800 Hz for F1 and 600 and 1400 Hz for F2, for vowel "u" 100 and 400 Hz for F1 and 400 and 1200 Hz for F2. At low frequencies it is feasible to invoke the source-filter model of voice production and associate vowel identity with frequencies of the first two formants in the voice spectrum. On the other hand, subject to intonation, singing or other forms of exposed voice (such as emotional speech, focused speech), the formant regions tend to spread. In spectral analysis other frequencies dominate, so specific formant frequency bands are not easily recognizable. Although the resulting formant map is not much different from the formant

  13. THE BOSS EMISSION-LINE LENS SURVEY. IV. SMOOTH LENS MODELS FOR THE BELLS GALLERY SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Yiping [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Bolton, Adam S.; Montero-Dorta, Antonio D.; Cornachione, Matthew A.; Zheng, Zheng; Brownstein, Joel R. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States); Mao, Shude [Physics Department and Tsinghua Centre for Astrophysics, Tsinghua University, Beijing 100084 (China); Kochanek, Christopher S. [Department of Astronomy and Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Pérez-Fournon, Ismael; Marques-Chaves, Rui [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 San Cristóbal de La Laguna, Tenerife (Spain); Oguri, Masamune [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ménard, Brice, E-mail: yiping.shu@nao.cas.cn [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2016-12-20

    We present Hubble Space Telescope F606W-band imaging observations of 21 galaxy-Ly α emitter lens candidates in the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Ly α EmitteR sYstems (BELLS GALLERY) survey. Seventeen systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately 0.55, while the lensed sources are Ly α emitters (LAEs) at redshifts from two to three. Although most of the lens systems are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are, on average, 60% larger than those of the BELLS lenses because of the much higher source redshifts. This will allow for a detailed investigation of the radius evolution of the mass profile in ETGs. With the aid of the average ∼13× lensing magnification, the LAEs are frequently resolved into individual star-forming knots with a wide range of properties. They have characteristic sizes from less than 100 pc to several kiloparsecs, rest-frame far-UV apparent AB magnitudes from 29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.

  14. Mycelial carton galleries of Azteca brevis (Formicidae) as a multi-species network

    Science.gov (United States)

    Mayer, Veronika E.; Voglmayr, Hermann

    2009-01-01

    Apart from growing fungi for nutrition, as seen in the New World Attini, ants cultivate fungi for reinforcement of the walls of their nests or tunnel-shaped runway galleries. These fungi are grown on organic material such as bark, epiphylls or trichomes, and form stable ‘carton structures’. In this study, the carton of the runway galleries built by Azteca brevis (Formicidae, Dolichoderinae) on branches of Tetrathylacium macrophyllum (Flacourtiaceae) is investigated. For the first time, molecular tools are used to address the biodiversity and phylogenetic affinities of fungi involved in tropical ant carton architecture, a previously neglected ant–fungus mutualism. The A. brevis carton involves a complex association of several fungi. All the isolated fungi were unequivocally placed within the Chaetothyriales by DNA sequence data. Whereas five types of fungal hyphae were morphologically distinguishable, our DNA data showed that more species are involved, applying a phylogenetic species concept based on DNA phylogenies and hyphal morphology. In contrast to the New World Attini with their many-to-one (different ant species—one fungal cultivar) pattern, and temperate Lasius with a one-to-two (one ant species—two mutualists) or many-to-one (different ant species share the same mutualist) system, the A. brevis–fungi association is a one-to-many multi-species network. Vertical fungus transmission has not yet been found, indicating that the A. brevis–fungi interaction is rather generalized. PMID:19556257

  15. The Art Gallery Test: A Preliminary Comparison between Traditional Neuropsychological and Ecological VR-Based Tests

    Directory of Open Access Journals (Sweden)

    Pedro Gamito

    2017-11-01

    Full Text Available Ecological validity should be the cornerstone of any assessment of cognitive functioning. For this purpose, we have developed a preliminary study to test the Art Gallery Test (AGT as an alternative to traditional neuropsychological testing. The AGT involves three visual search subtests displayed in a virtual reality (VR art gallery, designed to assess visual attention within an ecologically valid setting. To evaluate the relation between AGT and standard neuropsychological assessment scales, data were collected on a normative sample of healthy adults (n = 30. The measures consisted of concurrent paper-and-pencil neuropsychological measures [Montreal Cognitive Assessment (MoCA, Frontal Assessment Battery (FAB, and Color Trails Test (CTT] along with the outcomes from the three subtests of the AGT. The results showed significant correlations between the AGT subtests describing different visual search exercises strategies with global and specific cognitive measures. Comparative visual search was associated with attention and cognitive flexibility (CTT; whereas visual searches involving pictograms correlated with global cognitive function (MoCA.

  16. The Art Gallery Test: A Preliminary Comparison between Traditional Neuropsychological and Ecological VR-Based Tests

    Science.gov (United States)

    Gamito, Pedro; Oliveira, Jorge; Alghazzawi, Daniyal; Fardoun, Habib; Rosa, Pedro; Sousa, Tatiana; Maia, Ines; Morais, Diogo; Lopes, Paulo; Brito, Rodrigo

    2017-01-01

    Ecological validity should be the cornerstone of any assessment of cognitive functioning. For this purpose, we have developed a preliminary study to test the Art Gallery Test (AGT) as an alternative to traditional neuropsychological testing. The AGT involves three visual search subtests displayed in a virtual reality (VR) art gallery, designed to assess visual attention within an ecologically valid setting. To evaluate the relation between AGT and standard neuropsychological assessment scales, data were collected on a normative sample of healthy adults (n = 30). The measures consisted of concurrent paper-and-pencil neuropsychological measures [Montreal Cognitive Assessment (MoCA), Frontal Assessment Battery (FAB), and Color Trails Test (CTT)] along with the outcomes from the three subtests of the AGT. The results showed significant correlations between the AGT subtests describing different visual search exercises strategies with global and specific cognitive measures. Comparative visual search was associated with attention and cognitive flexibility (CTT); whereas visual searches involving pictograms correlated with global cognitive function (MoCA). PMID:29204128

  17. The Art Gallery Test: A Preliminary Comparison between Traditional Neuropsychological and Ecological VR-Based Tests.

    Science.gov (United States)

    Gamito, Pedro; Oliveira, Jorge; Alghazzawi, Daniyal; Fardoun, Habib; Rosa, Pedro; Sousa, Tatiana; Maia, Ines; Morais, Diogo; Lopes, Paulo; Brito, Rodrigo

    2017-01-01

    Ecological validity should be the cornerstone of any assessment of cognitive functioning. For this purpose, we have developed a preliminary study to test the Art Gallery Test (AGT) as an alternative to traditional neuropsychological testing. The AGT involves three visual search subtests displayed in a virtual reality (VR) art gallery, designed to assess visual attention within an ecologically valid setting. To evaluate the relation between AGT and standard neuropsychological assessment scales, data were collected on a normative sample of healthy adults (n = 30). The measures consisted of concurrent paper-and-pencil neuropsychological measures [Montreal Cognitive Assessment (MoCA), Frontal Assessment Battery (FAB), and Color Trails Test (CTT)] along with the outcomes from the three subtests of the AGT. The results showed significant correlations between the AGT subtests describing different visual search exercises strategies with global and specific cognitive measures. Comparative visual search was associated with attention and cognitive flexibility (CTT); whereas visual searches involving pictograms correlated with global cognitive function (MoCA).

  18. Immobilization of hemoglobin at the galleries of layered niobate HCa2Nb3O10.

    Science.gov (United States)

    Gao, Lu; Gao, Qiuming; Wang, Qigang; Peng, Shuge; Shi, Jianlin

    2005-09-01

    Hemoglobin (Hb) was intercalated at the galleries of layered niobate HCa(2)Nb(3)O(10) (HCNO). Two different kinds of layered phases of Hb-CNO composites Hb-CNO-1 and Hb-CNO-2 were obtained with the interlayer distances of 7.2 and 10.3nm in correspondence with the monolayer and bilayer arrangements of proteins between the niobate layers, respectively, based on the powder XRD pattern, HRTEM, UV-vis spectra and CHN analyses. FTIR spectra of Hb-CNO composites show that amide I and amide II bands were actually the same as those of the native Hb, which indicates that there is almost no structural change after immobilization. Michaelis-Menten model methods were used to study the peroxidatic activity of the reaction of 2-methoxyphenol and H(2)O(2) for the entrapped Hb in the galleries of HCNO. Compared to that of free Hb, the kinetic parameters of Hb-CNO k(cat), K(M) and k(cat)/K(M) were affected by the immobilization process. The immobilized Hb showed a higher relative activity than that of free Hb after incubated in phosphate buffer (pH = 7) at 80 degrees C for a period of time. The environments between the layers of HCNO are hydrophilic which will bind water tightly and help to stabilize the 'essential water' layer around the protein. So, immobilization of Hb between the layers of HCNO enhanced the activity of Hb in water-DMSO mixture.

  19. Juicebox Gallery

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... et 2014 – Ahmed K. Rashid

  20. Image Gallery

    Science.gov (United States)

    ... see Terms of Use . By Treatment Acupuncture Herbs Massage Tai Chi Yoga By Category Natural Products Manipulative Body-Based Mind-Body Medicine Time to Talk Campaign Whole Medical Systems Traditional Chinese Medicine © Bob Stockfield Courtesy: National Center for ...

  1. Juicebox Gallery

    International Development Research Centre (IDRC) Digital Library (Canada)

    2012 and 2014 IDRC Research Awardee Ahmed K. Rashid

  2. Multimode laser emission from free-standing cylindrical microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Jaison, E-mail: jaisonpeter@cusat.ac.in; Radhakrishnan, P.; Nampoori, V.P.N.; Kailasnath, M.

    2014-05-01

    We report a well resolved whispering gallery mode (WGM) laser emission from a free-standing microring cavity based on a dye doped hollow polymer optical fiber (DDHPOF), which is transversely pumped by a pulsed Nd:YAG laser. The microring laser is characterized by a well-defined, low threshold pump power at which the emission spectral intensity dramatically increases and collapses into several dominant microcavity laser modes with reduced mode spacing and high Q-value. Resonant modes are excited inside the gain medium which is strongly confined along the radial direction so that the spacing of lasing modes is controlled by the diameter of the cylindrical microcavity. A variation in the free spectral range of WGM spectra from 0.23 to 0.09 nm coupled with a red-shift is observed with an increase in the diameter of DDHPOFs. - Highlights: • Different diameter free-standing cylindrical microcavity lasers have been fabricated and their performances have been evaluated. • The microring laser is characterized by a well-defined, low threshold pump power, with reduced mode spacing and high Q-value. • When the diameter of DDHPOF increases, the number of lasing peaks increases along with the decrease of the FSR as observed from our studies. • It is also found that whispering gallery lasing envelope is shifted from 559 to 571 nm (Stokes shift) with the diameter.

  3. Rael Artel Gallery: Non-Profit Project Space : short tale of an experimental project's space tactics / Kiwa

    Index Scriptorium Estoniae

    Kiwa, pseud., 1975-

    2009-01-01

    Aastatel 2004-2008 Pärnus ja aastatel 2006-2008 Tartus tegutsenud Rael Artel Galeriist, mille looja ja moderaator oli Rael Artel. Galerii tegevus lõppes kunstialbumi "Hotell Pärnu : Rael Arel Gallery : Non Profit Project Space 2004-2008 / kontseptsioon ja toimetamine: Rael Artel" ilmumisega 2009. aastal

  4. Reporting on What Jane Saw 2.0: Female Celebrity and Sensationalism in Boydell’s Shakespeare Gallery

    Directory of Open Access Journals (Sweden)

    Janine Barchas

    2015-03-01

    Full Text Available This essay reports on ongoing efforts to build an accurate digital model of John Boydell’s popular Shakespeare Gallery precisely as it looked in August 1796—when a 20-year-old Jane Austen visited London’s sites, staying within a ten-minute walk from the gallery. The essay argues for the substantial difference between studying Boydell’s pictures in a paper volume (whether as lists, illustrations in books, or engraved folio plates and viewing them as an exhibition of paintings on walls, albeit virtual ones. For example, the digital reconstruction illuminated commissions from several female participants in Boydell’s male-dominated gallery, especially Angelica Kauffman (1741-1807 and Anne Seymour Damer (1749-1828. In addition, the essay also recounts how the celebrity of model Emma Hart/Hamilton (1765-1815 safeguarded one Boydell painting from oblivion while The Shakespeare Gallery proved the site of a strange form of self-promotion practiced by actress Mary Wells (1762-1829. Our digital visualization of an historic exhibition in 1796 brought the controversial celebrity of a few women artists into focus. In sum, this essay shows DH methodology in action while sampling what might be gleaned when digital tools serve historical scholarship in the humanities.

  5. Social Phenomenological Analysis as a Research Method in Art Education: Developing an Empirical Model for Understanding Gallery Talks

    Science.gov (United States)

    Hofmann, Fabian

    2016-01-01

    Social phenomenological analysis is presented as a research method to study gallery talks or guided tours in art museums. The research method is based on the philosophical considerations of Edmund Husserl and sociological/social science concepts put forward by Max Weber and Alfred Schuetz. Its starting point is the everyday lifeworld; the…

  6. Characteristics of UHF radio wave propagation in an underground gallery. Chika kodo wo tsutawaru goku chotanpa (UHF) no tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T.; Isei, T. (National Research Inst. for Pollution and Resources., Tsukuba, (Japan))

    1990-03-25

    UHF radio wave propagation along underground galleries is formulated using two methods so far proposed by other authors; one is based on characteristic equations and the other one makes use of simple geometrical image sources. Experimental measurements are carried out on the propagation of UHF waves of frequency 100 - 1500 MHz sent along two underground galleries; one of reinforced concrete wall and the other one of wooden timbering, the length being 400m or 200m and the area of cross section being 5.4 or 3.8 square meter respectively. It is demonstracted that the characteristics of wave propagation calculated by means of the geometrical image source method are in better agreement with the result obtained by the measurement compared with those by the characteristic equation method. Furthermore, numerical analysis using the geometrical image source method gives the following results; as the frequency of wave is increased, the attenuation constant of the wave propagating along an underground gallery decreases, becomes almost independent on the area of cross section of the gallery and insensitive to the kind of timbering materials. 5 refs., 11 figs.

  7. Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil).

    Science.gov (United States)

    Ragusa-Netto, J

    2015-01-01

    Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe the feeding habits and feeding niche breadth fluctuations of the Chaco chachalaca in relation to food resources abundance and diversity at the Miranda river gallery forest (Southern Pantanal). I also analyzed the relationships between Chaco chachalacas feeding activity and food resources abundance. This parameter (flowers and fruits) exhibited significant seasonal differences of abundance in which flowers were plentiful at the end of the dry, while fruits were abundant during the early wet season. However, food resources diversity to Chaco chachalacas exhibited no seasonal difference. Their feeding activity paralleled the availability of food resources, so that when some items were massively available an enhanced number of Chaco chachalacas foraged in the gallery forest, particularly during the prolonged dry season when they extensively used flowers and Genipa americana fruits. In fact, the Chaco chachalaca feeding niche breadth value presented low values in this period, while high values were common in the rest of the year. The flexible diet of this cracid, potentially favors their year round presence in the gallery forest, mainly during the prolonged dry season when the propensity for famine might be high. Since the Chaco chachalaca is among the largest and most abundant canopy frugivores in the gallery forest, it may contribute to forest regeneration, an underscored role due to the impact of annual floods and meandering dynamics on tree loss.

  8. The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Tâmara Dias Oliveira Machado

    Full Text Available BACKGROUND Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. OBJECTIVE To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs in the city of Palmas and to determine the rate of natural infection by trypanosomatids. METHODS Gallery forests and adjacent household areas were sampled on July (dry season and November (rainy season in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing. FINDINGS A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp. and 578 (22 spp. were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri. MAIN CONCLUSIONS These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins

  9. Structural and environmental variations in a continuum of gallery forest/savana stricto sensu in Itumirim, MG

    Directory of Open Access Journals (Sweden)

    Danilo José Santos Gomes

    2013-06-01

    Full Text Available This work verified the possible correlations among the variations of the strucuture, species diversity and variations of the substrate in a tree compartment in a continuum of Gallery Forest/Savana stricto sensu in Itumirim, southern of Minas Gerais. The soils of the areas of Gallery Forest, Transition Forest and Savana stricto sensu presented medium structure, high acidity with pH between 4.5 and 5.0 and high aluminum contents. The structural survey all over the patch presented 1,347 individuals distributed into 39 families, 77 genera and 102 species. The family Fabaceae stood out by the greatest richness of species followed by the families Myrtaceae, Lauraceae and Rubiaceae. The species Protium spruceanum and Myrsine umbellata were superior in all the phytosociological parameters, respectively, for all the areas of Gallery Forest and Savana stricto sensu. In the area of transition , the species Copaifera langsdorffii reached the highest values of basal area and absolute dominance; however, as regards to absolute density and cover value was the species Myrsine umbellata. Shannon's diversity indices (H' and Pielou's equatibility index (J' for the three places were of 3,57, 3,51 and 2,58 and 0,79, 0,88 and 0,77, respectively, for the areas of Gallery Forest, transition Forest and Savana stricto sensu. Through the rectified correspondence analysis (DCA, two groupings in the DCA diagram were found: grouping 1 containing only the three plots corresponding to the Savana stricto sensu; and grouping 2 joining together the other plots sampled encompassing the sites of Gallery and transition Forest.

  10. Nomes Sanumá entre gritos e sussuros Sanumá names between cries and whispers

    Directory of Open Access Journals (Sweden)

    Alcida Rita Ramos

    2008-05-01

    political life. With the arrival of outsiders, foreign names made their entrance in the Sanumá social lexicon, thus relieving the pressure over name secrecy. First came protestant missionaries with the Davids and Sarahs, then gold miners and other jungle adventurers with their regional and idisioncratic nicknames - Ceará, Paraíba, Passarão, etc. - greatly contributing to keep Sanumá personal names away from the public ear. It would thus seem that whispering would no longer be necessary, and crying out people’s names could be done at ease. Things, however, are not as they seem. To what extent Sanumá naming etiquette has reacted to these changes is what I intend to scrutinize.

  11. Lattices of dielectric resonators

    CERN Document Server

    Trubin, Alexander

    2016-01-01

    This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

  12. Diversity and Structure of the Gama Gallery Forest in Central Brazil in 2009

    Directory of Open Access Journals (Sweden)

    Roberto Tramontina Araujo

    2016-06-01

    Full Text Available The objective of this study was to evaluate the diversity and structure of the tree community of the Gama gallery forest, in the Federal District, in 2009. A total of 151 permanent plots of 10×20 m were allocated continually along ten lines perpendicular to the watercourse. All individuals with diameter at breast height (DBH equal or greater than 10 cm were tagged and measured. In total, 114 species in 52 families and 96 genera were identified. The density was 643 ind.ha-1, the basal area was 31.52 m2.ha-1 and 13 species were frequently at least in 25% of the plots. The Shannon index was 3.91 nats.ind-1 and the Pielou index was 82%, expressing the good conservation condition and the high diversity of the vegetation. The diameter distribution curve showed an "inverted J" pattern.

  13. PENINGKATAN AKTIVITAS DAN HASIL BELAJAR AKUNTANSI MATERI LAPORAN KEUANGAN MELALUI METODE GALLERY WALK DUATI-DUATA

    Directory of Open Access Journals (Sweden)

    Nining Mariyaningsih

    2014-06-01

    Full Text Available In learning accounting, conventional learning models are still frequently used by the teacher. As a result, the learning become monotonous and it’s not maximum. The problem of this study is wheather through Gallery Walk Duati-Duata can improve the activity and learning outcomes of accounting students.This study was class action research which was designed into two main cycles. Each cycle consisted of four stages started from planning, acting, observing and reflecting. The result showed that : (1 Learning activities increase from 27,78% before cycle, 69,45% in first cycle and 93,88% in second cycle, (2 The learning outcomes increase, from 22,22% before siklus, 75% in first cycle and 94,44% in second cycle. Therefore the use of this methods could be one of the reference of teachers in implementing the learning process.

  14. Analysis of borehole expansion and gallery tests in anisotropic rock masses

    Science.gov (United States)

    Amadei, B.; Savage, W.Z.

    1991-01-01

    Closed-form solutions are used to show how rock anisotropy affects the variation of the modulus of deformation around the walls of a hole in which expansion tests are conducted. These tests include dilatometer and NX-jack tests in boreholes and gallery tests in tunnels. The effects of rock anisotropy on the modulus of deformation are shown for transversely isotropic and regularly jointed rock masses with planes of transverse isotropy or joint planes parallel or normal to the hole longitudinal axis for plane strain or plane stress condition. The closed-form solutions can also be used when determining the elastic properties of anisotropic rock masses (intact or regularly jointed) in situ. ?? 1991.

  15. Voice over: Audio-visual congruency and content recall in the gallery setting.

    Science.gov (United States)

    Fairhurst, Merle T; Scott, Minnie; Deroy, Ophelia

    2017-01-01

    Experimental research has shown that pairs of stimuli which are congruent and assumed to 'go together' are recalled more effectively than an item presented in isolation. Will this multisensory memory benefit occur when stimuli are richer and longer, in an ecological setting? In the present study, we focused on an everyday situation of audio-visual learning and manipulated the relationship between audio guide tracks and viewed portraits in the galleries of the Tate Britain. By varying the gender and narrative style of the voice-over, we examined how the perceived congruency and assumed unity of the audio guide track with painted portraits affected subsequent recall. We show that tracks perceived as best matching the viewed portraits led to greater recall of both sensory and linguistic content. We provide the first evidence that manipulating crossmodal congruence and unity assumptions can effectively impact memory in a multisensory ecological setting, even in the absence of precise temporal alignment between sensory cues.

  16. Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery : [luuletused] / Artur Alliksaar

    Index Scriptorium Estoniae

    Alliksaar, Artur, 1923-1966

    2001-01-01

    Tekst eesti ja inglise k. A. Alliksaare lühibiograafia eesti ja inglise k. lk. 55. Sisu: Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery ; "Olen määratusuur mets..." = "I am infinitely vast forest..." ; "Olen koredate külgedega kalju..." = "I am rough-sided cliff..." ; "Olen meri, millel puudub äär..." = "I am sea that knows no bounds..." ; "Liikumine on niivõrd liitunud mu loomusega..." = "Movement is so much part of me..." ; "Ma ei söandaks öelda, et olen rikas..." = "I would not claim that I am rich..." ; Pöördehetk = Turning point ; Kuigi on nii palju lilli... = Though there are so many flowers ; Antidolorosum

  17. Diversity and biocide susceptibility of fungal assemblages dwelling in the Art Gallery of Magura Cave, Bulgaria

    Directory of Open Access Journals (Sweden)

    Milena M. Mitova

    2017-01-01

    Full Text Available Magura Cave, north-western Bulgaria, possesses valuable rock-art paintings made with bat guano and dated from the period between the Eneolithic and Bronze Ages. Since 2008, the Art Gallery is closed to the general public in order to protect the paintings from vandalism, microclimatic changes caused by visitors and artificial illumination, and the consequent growth of fungi and phototrophs. Nevertheless, some tourist visits are allowed under the supervision of cave managers. This study provides the first scientific report on cultivable fungal assemblages dwelling different substrata in the Art Gallery. A total of 78 strains, belonging to 37 OTUs (Ascomycota 81%, Zygomycota 13%, Basidiomycota 5%, were isolated in the study. This fungal diversity was clearly dominated by Penicillium (50% of strains and Aspergillus (13%. The most relevant visible fungal colonies were detected in sediments rich in bat guano, where, besides Penicillium, other guanophilic fungi such as Mucor, Mortierella, Trichosporon and Trichoderma were dominant. Conversely, scarce fungi were detected on rock surface of painted walls. Based on the biocide susceptibility assay, octylisothiazolinone (OIT and benzalkonium chloride (BAC were effective inhibiting the in vitro growth of dominant fungal species in Magura Cave, when applied at concentrations ranged from 100 to 1,000 mg/L. These data provide a valuable knowledge about Magura fungi, and exemplify a type of preliminary test that may be conducted before planning any biocide treatment. However, considering the irreversible effects of biocides on the ecological balance in caves, and the low fungal contamination in painted walls of Magura Cave, there is no reason to use conventional biocides in this cave. Further studies, monitoring microbial communities and microclimatic parameters, should be conducted to improve the knowledge on microbial ecology in Magura Cave and possible human impacts, as well as to allow the early detection

  18. Termite (Insecta, Isoptera assemblage of a gallery forest relic from the Chaco province (Argentina: taxonomic and functional groups

    Directory of Open Access Journals (Sweden)

    Godoy, M. C.

    2013-04-01

    Full Text Available Termite fauna of the gallery forest in the Colonia Benitez Reserve (Chaco province, Argentina were analyzed using the rapid diversity assessment protocol (100 x 2 m transects. Twelve species, 10 genera and two families (Kalotermitidae and Termitidae, were detected, comprising the four feeding groups recognized for termites. True soil–feeders (IV showed the highest species richness, and dead wood and grasses feeders (II had the highest relative abundance. The most frequently occupied microhabitats were dead wood pieces lying on the ground. These results indicate that the Reserve harbors a diverse termite community similar to the ‘monte fuerte’ isopteran fauna (91.6% shared species. Our findings also support the Reserve´s value as a well–preserved fragment of the original gallery forest and emphasize the need to promote its conservation.

  19. Development and validation of a CFD model predicting the backfill process of a nuclear waste gallery

    Energy Technology Data Exchange (ETDEWEB)

    Gopala, Vinay Ramohalli, E-mail: gopala@nrg.eu [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands); Lycklama a Nijeholt, Jan-Aiso [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands); Bakker, Paul [Van Hattum en Blankevoort, Woerden (Netherlands); Haverkate, Benno [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands)

    2011-07-15

    Research highlights: > This work presents the CFD simulation of the backfill process of Supercontainers with nuclear waste emplaced in a disposal gallery. > The cement-based material used for backfill is grout and the flow of grout is modelled as a Bingham fluid. > The model is verified against an analytical solution and validated against the flowability tests for concrete. > Comparison between backfill plexiglas experiment and simulation shows a distinct difference in the filling pattern. > The numerical model needs to be further developed to include segregation effects and thixotropic behavior of grout. - Abstract: Nuclear waste material may be stored in underground tunnels for long term storage. The example treated in this article is based on the current Belgian disposal concept for High-Level Waste (HLW), in which the nuclear waste material is packed in concrete shielded packages, called Supercontainers, which are inserted into these tunnels. After placement of the packages in the underground tunnels, the remaining voids between the packages and the tunnel lining is filled-up with a cement-based material called grout in order to encase the stored containers into the underground spacing. This encasement of the stored containers inside the tunnels is known as the backfill process. A good backfill process is necessary to stabilize the waste gallery against ground settlements. A numerical model to simulate the backfill process can help to improve and optimize the process by ensuring a homogeneous filling with no air voids and also optimization of the injection positions to achieve a homogeneous filling. The objective of the present work is to develop such a numerical code that can predict the backfill process well and validate the model against the available experiments and analytical solutions. In the present work the rheology of Grout is modelled as a Bingham fluid which is implemented in OpenFOAM - a finite volume-based open source computational fluid dynamics

  20. Using Value Proposition Design and Lean Method to Reduce Risks of Starting a Business : Case: Cuban Art Gallery

    OpenAIRE

    Junttila, Eero

    2015-01-01

    The objective of this thesis was to create modern dynamic version of business plan to help create products or services with lower risks. The aim of the thesis was to create a successful starting point for a Cuban art gallery by using latest knowledge in business model design to reduce uncertainties. The basic idea was to use Value Proposition Design to design the service around validated customer needs. This thesis includes quantitative researches that were made about customers and their ...

  1. Beyond the Gallery Forest: Contrasting Habitat and Diet in Lemur catta Troops at Bezà Mahafaly Special Reserve.

    Science.gov (United States)

    Yamashita, Nayuta; Sauther, Michelle L; Cuozzo, Frank P; Youssouf Jacky, Ibrahim Antho

    2015-01-01

    Ring-tailed lemurs have been studied intensively in the Parcel 1 gallery forest of Bezà Mahafaly Special Reserve. Here, we report on lemur groups in a mixture of deciduous dry forest and spiny forest just 5 km to the west. Compared to Parcel 1, Parcel 2 (P2) has a lower density of Tamarindus indica, a major dietary plant species for gallery forest lemurs. Recent studies in drier habitats have called into question the association of lemur density and tamarind presence. In order to address this question, we measured forest structure and composition of plant plots between parcels and conducted lemur feeding observations. The trees and shrubs within the parcels did not differ in height or diameter at breast height, but the frequencies of plant species that were common between parcels were significantly different. Numbers of feeding observations on foods common to both parcels did not differ, but their relative rankings within parcels did. Frequencies of food plants corresponded to earlier reports of lemur population densities. However, we found that the ring-tailed lemur diet is a mixture of plants that are eaten in abundance regardless of frequency and those that are locally available. In terms of their reliance on Tamarindus, P2 animals appear intermediate between those in gallery forests and nontamarind sites. © 2015 S. Karger AG, Basel.

  2. Whispers of the Unspeakable: New York and Montreal Newspaper Coverage of the Oscar Wilde Trials in 1895

    Directory of Open Access Journals (Sweden)

    Greg Robinson

    2015-03-01

    Full Text Available Greg Robinson’s article “Whispers of the Unspeakable: New York and Montreal Newspaper Coverage of the Oscar Wilde Trials in 1895,” originally published in 2010 in the French-language journal Rue des Beaux Arts, no. 24 (2010, is here republished and—with much gratitude—translated (for the original text, please see http://www.oscholars.com/RBA/twenty-four/24.7/Articles.htm. Robinson’s transnational study focuses on how reading the specific language of newspaper reports of the Oscar Wilde case, literally from a distance, from places less emotionally attached to and nationally distinct from the scandal’s epicenter in London, England, provides insight into “the state of everyday public knowledge and discussion of (homosexuality, at least west of the Atlantic”; thus Robinson’s fascinating research, which involves numerous newspapers—from the elite New York Times to the New York Herald, from the Montreal Daily Star to the French-language papers of Quebec—concludes that the popular press, read transnationally, offers key insights into the developing attitudes toward and levels of interest in the newly forming identity of the “homosexual” across societies.

  3. Emergence: A Planetarium and Art Gallery Collaboration Between Artist, Astronomer, and Musician

    Science.gov (United States)

    Beaver, J.; Waller, J. B.; Turner, M.

    2011-09-01

    We describe an unusual planetarium program and art gallery exhibition that premiered in Menasha, Wisconsin. Emergence combines fine art and improvisational music with astronomy and physics. The authors, Judith Baker Waller, John Beaver, and Matt Turner, are, respectively, artist, astronomer, and musician. All three acted as partners in planning and executing the final production. The overall goal of Emergence is to use art, music, and natural science each as a point of departure to learn about the others, and to explore the interaction between humans and the natural world and the differences and commonalities between art, science, and music. Of particular interest, the planetarium portion includes techniques that are, so far as we know, unique. Each night the show is different, the details chosen randomly, but always according to the same theoretical scheme. Various elements are parameterized, the show varying with time according to subroutines that dictate the overall pacing and look, but with details always chosen randomly according to prearranged probabilities. We believe that some of these techniques could be of interest to others who wish to explore the unique possibilities of the planetarium as educational performance space. We argue that this provides a useful format for collaborations between artist and scientist, as scientific content can be delivered in a way that is consistent with the concerns of the artist. We describe some of the approaches taken toward these ends in Emergence, and some of the lessons learned about the process of collaboration between a scientist, a visual artist and a performing artist.

  4. Berenty Reserve—A Gallery Forest in Decline in Dry Southern Madagascar—Towards Forest Restoration

    Directory of Open Access Journals (Sweden)

    Vanessa Winchester

    2018-01-01

    Full Text Available Berenty Reserve, a fully protected gallery forest beside the Mandrare River is renowned for its lemurs, but the continuous canopy of the main forest is shrinking, fragmenting and degrading. The aim of this study, before any restoration can be considered, is to investigate why canopy-cover is declining and define the forest’s vegetation status and composition. Our study includes analysis of tamarind age (the dominant species and regeneration, forest extent, climate and soil. Measurement of trunk circumference and annual rings indicated a median age of 190 years, near the accepted maximum for tamarinds. There is no regeneration of tamarind seedlings under the canopy and an invasive vine, Cissus quadrangularis suffocates any regeneration on the forest margins. A vegetation survey, based on fifteen transects, broadly characterized three forest areas: continuous canopy near the river, transitional canopy with fewer tall trees, and degraded dryland; the survey also provided a list of the 18 most common tree species. Ring counts of flood-damaged roots combined with measurement to the riverbank show that erosion rates, up to 19.5 cm/year, are not an immediate threat to forest extent. The highly variable climate shows no trend and analysis of forest soil indicates compatibility with plant growth.

  5. A Review of Islamic Astronomical Artifacts in Sultan Haji Hassanal Bolkiah Islamic Exhibition Gallery, Brunei Darussalam

    Science.gov (United States)

    Noor, Nor Azam Mat

    2012-09-01

    The study of ancient artifacts is a branch of an ethnographic which includes a socio-cultural community that contributes to the development of civilization. In this case, it can be seen how a community showcase their respective cultures that would have triggered the views and thoughts within their civilization. How culture evolved can be seen from a perspective that although the Persian and Arab neighboring but very different in terms of creativity and their cosmological view. Results demonstrate both artifacts although there are similarities in the symbols of the constellation, but not all in the same cosmos thinking because it is influenced by the myth of the local people. Thus the study of artifacts is to consider the effects of a branch of archaeoastronomy and separate studies that approach on events using celestial navigation apart from the assimilation of science and technology. The study of such artifacts is very important in review of the purpose and scope of the establishment of a gallery and museum as a valuable item such as a heritage and artistic treasures of the world that must be given priority and documenting all the artifacts of which are for aesthetic value.

  6. Voice over: Audio-visual congruency and content recall in the gallery setting

    Science.gov (United States)

    Fairhurst, Merle T.; Scott, Minnie; Deroy, Ophelia

    2017-01-01

    Experimental research has shown that pairs of stimuli which are congruent and assumed to ‘go together’ are recalled more effectively than an item presented in isolation. Will this multisensory memory benefit occur when stimuli are richer and longer, in an ecological setting? In the present study, we focused on an everyday situation of audio-visual learning and manipulated the relationship between audio guide tracks and viewed portraits in the galleries of the Tate Britain. By varying the gender and narrative style of the voice-over, we examined how the perceived congruency and assumed unity of the audio guide track with painted portraits affected subsequent recall. We show that tracks perceived as best matching the viewed portraits led to greater recall of both sensory and linguistic content. We provide the first evidence that manipulating crossmodal congruence and unity assumptions can effectively impact memory in a multisensory ecological setting, even in the absence of precise temporal alignment between sensory cues. PMID:28636667

  7. Orchid bee (Hymenoptera: Apidae community from a gallery forest in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    Francinaldo S Silva

    2012-06-01

    Full Text Available The orchid bees are a very important group of pollinators distributed in the Neotropics. Although a lot of studies concerning male euglossine bees have been done in this region, few works have so far been carried out in the Cerrado biome. This manuscript has the main objective to present the orchid bee community from a Gallery Forest in the Northeastern Brazilian Cerrado landscape, taking account the species composition, abundance, seasonality and hourly distribution. Male euglossine bees were collected monthly from October 2007 to May 2009, in the Reserva Florestal da Itamacaoca belonging to the Companhia de Água e Esgoto do Maranhão, in Chapadinha municipality, Maranhão State. The scents eucalyptol, eugenol and vanillin were utilized, between 07:00 and 17:00hr, to attract the euglossine males. Cotton balls were dampened with the scents and suspended by a string on tree branches 1.5m above soil level, set 8m from one another. The specimens were captured with entomological nets, killed with ethyl acetate and transported to the laboratory to be identified. A total of 158 individuals and 14 species of bees were recorded. The genus Eulaema was the most representative group of euglossine bees in relation to the total number of the sampled individuals, accounting for 50.6% of bees followed by Euglossa (26.6%, Eufriesea (15.2% and Exaerete (7.6%. The most frequent species were Eulaema nigrita (27.8%, Eulaema cingulata (19% and Euglossa cordata (18.3%. Many species typical of forested environments were found in samples, like Euglossa avicula, Euglossa violaceifrons and Eulaema meriana, emphasizing the role played by the Gallery Forests as bridge sites to connect the two great biomes of Amazonia and Atlantic Forest. The occurrence of Exaerete guaykuru represents the second record of this species for the Neotropical region, and both records coming from the Gallery Forest zones. The male euglossine bees were sampled mainly in the dry season, where 62

  8. Feasibility of Gallery Intake Systems for Seawater Reverse Osmosis Facilities along the Northern Red Sea Coast of Saudi Arabia

    KAUST Repository

    Dehwah, Abdullah

    2012-03-01

    The Kingdom of Saudi Arabia is dependent on desalination of seawater to provide new water supplies for the future. Desalination is expensive and it is very important to reduce the cost and lower the energy consumption. Most seawater reverse osmosis facilities use open-ocean intakes, which require extensive pre-treatment processes to remove particulate and biological materials that cause operating problems. An alternative intake is the subsurface system which utilizes the concept of riverbank filtration using wells or galleries and provides natural filtration to improve the quality of feedwater before it enters the desalination plant. This reduces operating cost and lowers energy consumption. Research was focused on evaluating gallery-type intakes (beach and seabed galleries) that could be used along the Northern Red Sea shoreline to provide a better quality feedwater for desalination. The geological characteristics of the visited sites were favorable for the development of seabed filter systems (offshore), but not for beach gallery intakes. The low wave energy along the shoreline and the presence of mud or rocky coasts made beach galleries infeasible. One of the potentially favorable sites for a seabed filter was located in the nearshore area at King Abdullah Economic City (KAEC). This site has a predominantly sandy offshore bottom with shallow water depths, and a low tide range. In addition, the bottom is always covered with water and contains soft limestone unit below the sand mantle that could be easy excavated to facilitate the construction of a seabed filter. About 50 sediment samples were collected from the site and laboratory measurements were performed on them. Grain size distribution, porosity and hydraulic conductivity measurements were performed on the sediment samples. In addition, six statistical methods were used to estimate the hydraulic conductivity values. Based on results of lab measurements, field observations, tide ranges and sediment types, it

  9. Technical feasibility of using gallery intakes for seawater RO facilities, northern Red Sea coast of Saudi Arabia: The King Abdullah Economic City site

    KAUST Repository

    Dehwah, Abdullah

    2013-02-13

    The Kingdom of Saudi Arabia is dependent on desalination of seawater to provide new water supplies for the future. Desalination is expensive and it is very important to reduce the cost and lower the energy consumption. Most seawater reverse osmosis facilities use open-ocean intakes, which require extensive pretreatment processes to remove particulate and biological materials that cause operating problems such as membrane fouling or shutdown during algal blooms. Subsurface systems, using the concept of riverbank filtration, can be used as intakes. These systems include wells of various designs and galleries that provide natural filtration and biological treatment to improve the quality of feed water before it enters the desalination plant. This reduces operating cost, lowers chemical and energy consumption, and reduces environmental impacts. Technical feasibility of gallery-type intakes, beach and seabed types, for use as intakes to seawater reverse osmosis (RO) facilities was evaluated along the northern Red Sea shoreline of Saudi Arabia. The geological characteristics of the offshore ocean bottom were found to be favorable for the development of seabed gallery systems, but the shoreline geology was not adequate for the development of beach gallery intakes. One of the potentially favorable sites for a seabed gallery system was located in the nearshore area at King Abdullah Economic City (KAEC). Detailed investigation of the site hydrology (tides and wave action), sediment grain size characteristics, and sediment hydraulic conductivity, and access for construction were assessed. It was determined that seabed gallery development is favorable at the site. Based on the seawater that has a salinity of about 41,000 mg/L and a conversion rate of 40%, a conservatively designed gallery cell with dimensions of 100 by 50 m would produce about 25,000 m3/day of filtered seawater and seven cells (6 primary and 1 standby) could support a 60,000 m3/day (permeate) seawater RO plant

  10. Intense echolocation calls from two ;whispering' bats, Artibeus jamaicensis and Macrophyllum macrophyllum (Phyllostomidae)

    DEFF Research Database (Denmark)

    Brinkløv, Signe; Kalko, Elisabeth K V; Surlykke, Annemarie

    2009-01-01

    with entirely different foraging strategies. Macrophyllum macrophyllum hunts insects on the wing and gaffs them with its tail membrane and feet from or above water surfaces whereas Artibeus jamaicensis picks fruit from vegetation with its mouth. Recordings were made from bats foraging on the wing in a flight...... of Phyllostomidae have been categorised as low intensity (whispering) gleaners, assumed to emit echolocation calls with low source levels (approximately 70 dB SPL measured 10 cm from the bat's mouth). We used a multi-microphone array to determine intensities emitted from two phyllostomid bats from Panamá...

  11. Contributions by Host Trees and Insect Activity to Bacterial Communities in Dendroctonus valens (Coleoptera: Curculionidae) Galleries, and Their High Overlap With Other Microbial Assemblages of Bark Beetles.

    Science.gov (United States)

    Mason, Charles J; Hanshew, Alissa S; Raffa, Kenneth F

    2016-04-01

    Bark beetles are associated with a diversity of symbiotic microbiota that can mediate interactions with their host plants. Dendroctonus valens LeConte is a widely distributed bark beetle in North and Central America, and initiates solitary attacks on several species of Pinus in the Great Lakes region. In this study, we aimed to further characterize the bacterial community associated with D. valens feeding galleries using next-generation sequencing, and the possible contributions of both tree-resident and insect-associated bacteria to these consortia. We found that D. valens galleries harbor a diversity of microbial associates. Many of these associates were classified into a few taxonomic groups, of which Gammaproteobacteria were the most abundant class. Of the Gammaproteobacteria detected, many formed clades with 16S-rRNA sequences of bacteria previously associated with D. valens Many of the bacteria sequences detected in the galleries were similar to bacteria that function in detoxification, kairomone metabolism, and nitrogen fixation and cycling. The abundance of bacteria in galleries were 7× and 44× higher than in the surrounding uninfested tissues, and that were not attacked by D. valens, respectively. This suggests that the bacteria present in beetle galleries are largely introduced by D. valens and proliferate in this environment. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  12. The Restoration of Paintings at the Beginning of the Nineteenth Century in the Imperial Gallery

    Directory of Open Access Journals (Sweden)

    Alice Hoppe-Harnoncourt

    2012-04-01

    Full Text Available Les tableaux de la collection impériale à Vienne ont subi différentes phases de restauration. Dans la plupart des cas, celles-ci sont en rapport avec des évènements dans l´histoire de la galerie. Autour de l´année 1800, les traitements avaient généralement pour fonction d’adapter les peintures au goût du jour : beaucoup de changements de formats peuvent être retracés jusqu’à cette date ou les années précédentes. En revanche, après les guerres napoléoniennes, les interventions étaient de nature différente : la plupart des tableaux sur bois de la galerie ont été parquetés durant cette période. Appliquée systématiquement, cette méthode était apparemment considérée comme une solution de conservation à long terme.The paintings in the Imperial collection in Vienna underwent several phases of restoration treatments. In most cases they can be linked to events in the history of the picture gallery. In the years around 1800 the treatments seemed to be caused mainly by aesthetical aspects: many changes to the format of the paintings can be traced to that time. However, the treatments after the era of the Napoleonic wars were different: Most of the gallery’s panel paintings were cradled at that time. Since this method was applied systematically, it was probably considered as solution for a long lasting conservation.

  13. Shooting Gallery Operation in the Context of Establishing a Medically Supervised Injecting Center: Sydney, Australia

    Science.gov (United States)

    Dolan, Kate

    2007-01-01

    Shooting galleries (SGs) are illicit off-street spaces close to drug markets used for drug injection. Supervised injecting facilities (SIFs) are low threshold health services where injecting drug users (IDUs) can inject pre-obtained drugs under supervision. This study describes SG use in Kings Cross, Sydney before and after the opening of the Sydney Medically Supervised Injecting Centre (MSIC), Australia’s first SIF. Operational and environmental characteristics of SGs, reasons for SG use, and willingness to use MSIC were also examined. An exploratory survey of SG users (n = 31), interviews with SG users (n = 17), and drug workers (n = 8), and counts of used needles routinely collected from SGs (6 months before and after MSIC) and visits to the MSIC (6 months after MSIC) were triangulated. We found five SGs operated during the study period. Key operational characteristics were 24-h operation, AUS$10 entry fee, 30-min time limit, and dual use for sex work. Key reasons for SG use were to avoid police, a preference not to inject in public, and assistance from SG operators in case of overdose. SG users reported high levels of willingness to use the MSIC. The number of used needles collected from SGs decreased by 69% (41,819 vs. 12,935) in the 6 months after MSIC opened, while MSIC visits increased incrementally. We conclude that injections were transferred from SGs to the MSIC, but SGs continued to accommodate injections and harm reduction outreach should be maintained. PMID:17273925

  14. Crafting glass vessels: current research on the ancient glass collections in the Freer Gallery of Art, Washington, D.C.

    Science.gov (United States)

    Nagel, Alexander; McCarthy, Blythe; Bowe, Stacy

    Our knowledge of glass production in ancient Egypt has been well augmented by the publication of recently excavated materials and glass workshops, but also by more recent materials analysis, and experiments of modern glass-makers attempting to reconstruct the production process of thin-walled coreformed glass vessels. From the mounting of a prefabricated core to the final glass product our understanding of this profession has much improved. The small but well preserved glass collection of the Freer Gallery of Art in Washington, D.C. is a valid tool for examining and studying the technology and production of ancient Egyptian core formed glass vessels. Charles Lang Freer (1854-1919) acquired most of the material from Giovanni Dattari in Cairo in 1909. Previously the glass had received only limited discussion, suggesting that most of these vessels were produced in the 18th Dynasty in the 15th and 14th centuries BCE, while others date from the Hellenistic period and later. In an ongoing project we conducted computed radiography in conjunction with qualitative x-ray fluorescence analysis on a selected group of vessels to understand further aspects of the ancient production process. This paper will provide an overview of our recent research and present our data-gathering process and preliminary results. How can the examinations of core formed glass vessels in the Freer Gallery contribute to our understanding of ancient glass production and technology? By focusing on new ways of looking at old assumptions using the Freer Gallery glass collections, we hope to increase understanding of the challenges of the production process of core-vessel technology as represented by these vessels.

  15. Use of beach galleries as an intake for future seawater desalination facilities in Florida and globally similar areas

    KAUST Repository

    Missimer, Thomas M.

    2013-06-17

    Desalination of seawater using the reverse osmosis process can be made less costly by the use of subsurface intake systems. Use of conventional open-ocean intakes requires the addition of a number of pretreatment processes to protect the primary RO process. Despite using the best designs possible for the pretreatment, seawater RO membranes tend to biofoul because of the naturally-occurring organic material and small bacteria present in seawater. These materials are not completely removed by the pretreatment system and they pass through the cartridge filters into the membranes, thereby causing frequent and expensive cleaning of the membranes. Quality of the raw water can be greatly improved by the use of subsurface intakes which can substantially reduce the overall treatment cost. There are a number of possible subsurface designs that can be used including conventional vertical wells, horizontal wells, collector wells, beach galleries, and seabed filters. The key selection criteria for the type of subsurface intake most suited and most cost-effective for a site are based on the required volume of raw water and the local geology. The active shorelines of Florida are very well-suited for the development of beach gallery intake systems. These systems are installed beneath the active beach between the high and low tide zones of the beach. Since they are constructed with a depth to the screens between 3 and 5 m, they cannot be observed at surface and persons using the beach would be unaware of their existence. These galleries are simple to construct and they tend not to clog because the active wave action within the intertidal zone provides mechanical energy that continuously cleans the filter face. They also have other advantages, including: the water quality is seawater unaffected by substances present in freshwater aquifers occurring landward of the shoreline, the salinity of the water is generally constant, and there are no impacts on water users located inland from

  16. Deformed microcavity quantum cascade lasers with directional emission

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qijie; Yan Changling; Diehl, Laurent; Yu Nanfang; Pfluegl, Christian; Belkin, Mikhail A; Capasso, Federico [School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Hentschel, Martina [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Wiersig, Jan [Institut fuer Theoretische Physik, Universitaet Magdeburg, Postfach 4120, D-39016 Magdeburg (Germany); Edamura, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi [Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu 434-8601 (Japan)], E-mail: ldiehl@seas.harvard.edu, E-mail: capasso@seas.harvard.edu

    2009-12-15

    We report the experimental realization of deformed microcavity quantum cascade lasers (QCLs) with a Limacon-shaped chaotic resonator. Directional light emission with a beam divergence of {theta}{sub parallel}{approx}33 deg. from QCLs emitting at {lambda}{approx}10 {mu}m was obtained in the plane of the cavity for deformations in the range 0.37<{epsilon}<0.43. An excellent agreement between measured and calculated far-field profiles was found. Both simulations and experiments show that the Limacon-shaped microcavity preserves whispering gallery-like modes with high Q-factors for low deformations ({epsilon}<0.50). In addition, while the measured spectra show a transition from whispering gallery-like modes to a more complex mode structure at higher pumping currents, we observed 'universal far-field behavior' for different intracavity mode distributions in the Limacon microcavity, which can be explained by the distribution of unstable manifolds in ray optics simulations. Furthermore, the performance of the deformed microcavity lasers is robust with respect to variations of the deformation near its optimum value {epsilon}=0.40, which implies that this structure reduces the requirements on photolithography fabrication. The successful realization of these microcavity lasers may lead to applications in optoelectronics.

  17. ‘The catalogues of the Orchard Gallery: a contribution to critical and historical discourses in Northern Ireland, 1978-2003’

    OpenAIRE

    Gabriel Gee

    2013-01-01

    The Orchard Gallery opened in Derry in 1978. It was set up by Derry City Council, which appointed a then young artist and art teacher, Declan McGonagle, as its first exhibition director. In 1979-80, D. McGonagle convinced the council that the money it wanted to allocate to acquire works and establish a collection should be used to commission artists and art critics to produce artists’ books and publications. The artistic programme of the Orchard gallery aimed to exhibit a wide range of artist...

  18. Natural air ventilation in underground galleries as a tool to increase radon sampling volumes for geologic monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Eff-Darwich, Antonio [Departamento de Edafologia y Geologia, Universidad de La Laguna, Av. Astrofisico Francisco, Sanchez s/n, 38206 La Laguna, Tenerife (Spain); Instituto de Astrofisica de Canarias, c/Via Lactea s/n, 38205 La Laguna, Tenerife (Spain)], E-mail: adarwich@ull.es; Vinas, Ronaldo [Departamento de Edafologia y Geologia, Universidad de La Laguna, Av. Astrofisico Francisco, Sanchez s/n, 38206 La Laguna, Tenerife (Spain); Soler, Vicente [Estacion Volcanologica de Canarias, IPNA-CSIC, Av. Astrofisico Francisco Sanchez s/n, 38206 La Laguna, Tenerife (Spain); Nuez, Julio de la; Quesada, Maria L. [Departamento de Edafologia y Geologia, Universidad de La Laguna, Av. Astrofisico Francisco, Sanchez s/n, 38206 La Laguna, Tenerife (Spain)

    2008-09-15

    A simple numerical model was implemented to infer airflow (natural ventilation) in underground tunnels from the differences in the temporal patterns of radon, {sup 222}Rn, concentration time-series that were measured at two distant points in the interior of the tunnels. The main purpose of this work was to demonstrate that the installation of radon monitoring stations closer to the entrance of the tunnels was sufficient to remotely analyse the distribution of radon concentration in their interiors. This could ease the monitoring of radon, since the effective sampling volume of a single monitoring station located closer to the entrance of a tunnel is approximately 30,000 times larger than the sampling volume of a sub-soil radon sensor. This methodology was applied to an underground gallery located in the volcanic island of Tenerife, Canary Islands. This island constitutes an ideal laboratory to study the geo-dynamical behaviour of radon because of the existence of a vast network of galleries that conforms the main water supply of the island.

  19. Post-occupancy evaluation of a restored industrial building: A contemporary art and design gallery in Mexico

    Directory of Open Access Journals (Sweden)

    J. Mundo-Hernández

    2015-12-01

    Full Text Available This paper presents the results obtained from a post-occupancy evaluation (POE study conducted in an old fabric building called “La Violeta”. This structure has been recently converted into a contemporary art gallery. La Violeta is located in Puebla City, Mexico. The building dates from the beginning of the 19th century; it was built and used as a textile factory until the first decades of the 20th century. This POE study aims to assess the new use of the building from the users׳ point of view. Methodology involves historical research of the building, analysis of the conversion strategy, walkthrough investigation, and a user survey. Questions regarding the re-utilization strategy used in the building and its current use are included in the survey, such as “How do people perceive the space regarding its functionality, accessibility, and comfort?” Although the re-utilization process destroyed several historic elements, the re-use of old industrial spaces that otherwise would be obsolete and disused seems pertinent. Developing small renovation projects as part of an integral and wider project seems feasible. Users perceive the building as comfortable but not properly advertised as an art gallery, and its location is difficult to find.

  20. What is the password? Female bark beetles (Scolytinae) grant males access to their galleries based on courtship song.

    Science.gov (United States)

    Lindeman, Amanda A; Yack, Jayne E

    2015-06-01

    Acoustic signals are commonly used by insects in the context of mating, and signals can vary depending on the stage of interaction between a male and female. While calling songs have been studied extensively, particularly in the Orthoptera, much less is known about courtship songs. One outstanding question is how potential mates are differentiated by their courtship signal characteristics. We examined acoustic courtship signals in a new system, bark beetles (Scolytinae). In the red turpentine beetle (Dendroctonus valens) males produce chirp trains upon approaching the entrance of a female's gallery. We tested the hypotheses that acoustic signals are honest indicators of male condition and that females choose males based on signal characteristics. Males generated two distinct chirp types (simple and interrupted), and variability in their prevalence correlated with an indicator of male quality, body size, with larger males producing significantly more interrupted chirps. Females showed a significant preference for males who produced interrupted chirps, suggesting that females distinguish between males on the basis of their chirp performances. We suggest that interrupted chirps during courtship advertise a male's size and/or motor skills, and function as the proverbial 'passwords' that allow him entry to a female's gallery. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. miRToolsGallery: a tag-based and rankable microRNA bioinformatics resources database portal

    Science.gov (United States)

    Chen, Liang; Heikkinen, Liisa; Wang, ChangLiang; Yang, Yang; Knott, K Emily

    2018-01-01

    Abstract Hundreds of bioinformatics tools have been developed for MicroRNA (miRNA) investigations including those used for identification, target prediction, structure and expression profile analysis. However, finding the correct tool for a specific application requires the tedious and laborious process of locating, downloading, testing and validating the appropriate tool from a group of nearly a thousand. In order to facilitate this process, we developed a novel database portal named miRToolsGallery. We constructed the portal by manually curating > 950 miRNA analysis tools and resources. In the portal, a query to locate the appropriate tool is expedited by being searchable, filterable and rankable. The ranking feature is vital to quickly identify and prioritize the more useful from the obscure tools. Tools are ranked via different criteria including the PageRank algorithm, date of publication, number of citations, average of votes and number of publications. miRToolsGallery provides links and data for the comprehensive collection of currently available miRNA tools with a ranking function which can be adjusted using different criteria according to specific requirements. Database URL: http://www.mirtoolsgallery.org

  2. Technical feasibility of a seabed gallery system for SWRO facilities at Shoaiba, Saudi Arabia, and regions with similar geology

    KAUST Repository

    Rodri­guez, Luis R. Lujan

    2013-09-02

    Subsurface intakes can be used as part of the pretreatment system for seawater reverse osmosis facilities. Wells of various designs and galleries are being used for intakes at many sites globally to reduce pretreatment costs, chemical usage, biofouling potential, and environmental impacts (entrainment and impingement). The goal of using a subsurface intake is to reduce or replace conventional pretreatment processes. A field and laboratory investigation was undertaken to assess the feasibility of developing a seabed gallery intake offshore near the Shoaiba seawater RO (SWRO) plant site (150,000 m3/d treatment capacity) that could be used to replace the current intake used for only the RO capacity. A survey of the beach and offshore area was made and 51 sediment samples were collected from the seabed for laboratory analysis of grain size distribution, porosity, and hydraulic conductivity. Field observations showed that the marine bottom has a low slope from the shoreline seaward a distance of about 100 m to a depth of about 1.0 m before it steepens to a depth of over 2 m at 150 m from shore. The site has a relativity thin cover of unlithified carbonate sands, 2-5 cm thick, sitting on a soft coralline limestone of Pleistocene age. The sediments investigated were found to be clean carbonate or slightly muddy carbonate sands with mean grain diameters ranging mostly between 0.25 and 0.5 mm. Most of the area investigated contained a mud percentage between 0 and 5%. The measured porosity values range between 0.33 and 0.45 and measured hydraulic conductivity values from about 1.6 to 79.5 m/d with 64.6 m/d being the maximum offshore value. A preliminary design was developed to meet the full operational capacity of the Shoaiba SWRO treatment plant which would require 375,000 m3/d of raw water to produce 150,000 m3/d of permeate (40% conversion assumed for Red Sea water with a TDS of 41,000 mg/L). The design of the RO plant uses 10 trains to produce the 150,000 m3/d of product

  3. Nanomaterial-enhanced frequency combs (Conference Presentation)

    Science.gov (United States)

    Armani, Andrea M.; Castro-Beltran, Rigoberto; Diep, Vinh; Gungor, Eda; Shen, Xiaoqin; Soltani, Soheil

    2017-02-01

    Optical cavities are able to confine and store specific wavelengths of light, acting as optical amplifiers at those wavelengths. Because the amount of amplification is directly related to the cavity quality factor (Q) (or the cavity finesse), frequency comb research has focused on high-Q and ultra-high Q microcavities fabricated from a range of materials using a variety of methods. In all cases, the comb generation relies on a nonlinear process known as parametric frequency conversion which is based on a third order nonlinear interaction and which results in four wave mixing (FWM). Clearly, this approach requires significant optical power, which was the original motivation for using ultra-high-Q cavities. In fact, the majority of research to date has focused on pursuing increasingly high Q factors. However, another strategy is to improve the nonlinearity of the resonator through intelligently designing materials for this application. In the present work, a suite of nanomaterials (organic and inorganic) have been intelligently designed with the explicit purpose to enhance the nonlinearity of the resonator and reducing the threshold for frequency comb generation in the near-IR. The nanomaterials do not change the structure of the comb and only act to reduce the comb threshold. The silica microcavity is used as a testbed for initial demonstration and verification purposes. However, the fundamental strategy is translatable to other whispering gallery mode cavities.

  4. Passion Trumps Pay: A Study of the Future Skills Requirements of Information Professionals in Galleries, Libraries, Archives and Museums in Australia

    Science.gov (United States)

    Howard, Katherine; Partridge, Helen; Hughes, Hilary; Oliver, Gillian

    2016-01-01

    Introduction: This paper explores the current and future skills and knowledge requirements of contemporary information professionals in a converged gallery, library, archive and museum sector (also referred to as the GLAM sector) in Australia. This research forms part of a larger study that investigated the education needs of information…

  5. Thermal Loss in High-Q Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Bahramzy, Pevand; Svendsen, Simon

    2014-01-01

    Tunable antennas are very promising for future generations of mobile communications, where antennas are required to cover a wide range operating bands. This letter aims at characterizing the loss mechanism of tunable antennas. Tunable antennas typically exhibit a high Quality factor (Q), which can...

  6. N*(1535) electroproduction at high Q2

    Energy Technology Data Exchange (ETDEWEB)

    G. Ramalho, M.T. Pena, K. Tsushima

    2012-04-01

    A covariant spectator quark model is applied to study the {gamma}N {yields} N*(1535) reaction in the large Q{sup 2} region. Starting from the relation between the nucleon and N*(1535) systems, the N*(1535) valence quark wave function is determined without the addition of any parameters. The model is then used to calculate the {gamma}N {yields} N*(1535) transition form factors. A very interesting, useful relation between the A{sub 1/2} and S{sub 1/2} helicity amplitudes for Q{sup 2} > GeV{sup 2}, is also derived.

  7. High-Q antennas: Simulator limitations

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pedersen, Gert Frølund

    2013-01-01

    Increasing the mesh steps - i.e. the accuracy of the model - of a structure leads to converging results towards reality. With high-field structures, discretization of the domain in a transient simulation becomes of important matter. It is shown in this work that for these structures convergence...

  8. A gallery of oil components, their metals and Re-Os signatures

    Science.gov (United States)

    Stein, Holly J.; Hannah, Judith L.

    2016-04-01

    Most sediment-hosted metallic ore deposits are one degree of freedom from hydrocarbon. That is, sulfide fluid inclusions may contain vestiges of travel in tandem with hydrocarbon-bearing fluids. For metallic ore deposits of stated metamorphic and magmatic origin, the degrees of freedom are several times more or, in some cases, no relationship exists. Still, the fetish for stereotyping and classifying ore types into hardline ore deposit models (or hybrid models when the data are wildly uncooperative) impedes our ability to move toward a better understanding of source rock. Fluids in the deeper earth, fluids in the crust, and the extraterrestrial rain of metals provide the Re-Os template for oil. So, too, this combination ultimately drives the composition of many metallic ore deposits. The world of crude oil and its complex history of maturation, migration, mixing, metal-rich asphaltene precipitation, and subsequent mobility of lighter and metal-poor components, is an untapped resource for students of ore geology. In the same way that Mississippi Valley-type lead and zinc deposits are described as the outcome of two converging and mixing fluids (metal-bearing and sulfur-bearing fluids), asphaltene precipitation can be an outcome of a lighter oil meeting and mixing with a heavier one. In the petroleum industry, this can spell economic disaster if the pore-space becomes clogged with a non-producible heavy oil or solid bitumen. In ore geology, sulfide precipitation on loss of permeability may create a Pb-Zn deposit. Petroleum systems provide a gallery of successive time-integrated Re-Os results. Heavy or biodegraded oils, if intersected by lighter oil or gas, can generate asphaltite or tar mats, and release a reservoir of still lighter oil (or gas). During this process there are opportunities for separation of metal-enriched aqueous fluids that may retain an imprint of their earlier hydrocarbon history, ultimately trapped in fluid inclusions. Salinity, temperature and p

  9. The Strossmayer Gallery in Zagreb in the interwar period: from a utopian project to a renowned institution

    Directory of Open Access Journals (Sweden)

    Ljerka Dulibic

    2016-12-01

    Full Text Available The basis of today’s Strossmayer Gallery’s collection is the bequest of European Old Masters’ paintings collected by Bishop J. J. Strossmayer (1815-1905, with the fundamental desire to enlarge the scope of the Croatian cultural tradition through the appropriation of European elite culture. The meaning and function of the Gallery changed considerably over time. Before WWI, the Strossmayer Gallery was a utopian project in the sense that its mission was not only to fabricate what was seen to be a missing artistic past, but also to create the foundations for a future, native art. After WWI, with the formation of the Kingdom of Serbs, Croats and Slovenes, the national state was, at least in some form, realized, and the Gallery now turned its attention to concrete matters. In this paper, we follow the paths of intensive professionalization of the wide range of activities in the interwar period, retracing not only the history of museum presentation, or the history of Art History and of Art Conservation in Croatia, but also some traces of the general development of the dynamic, intertwined and significant relationship between Art History, Art Conservation and the museum. Il nucleo dell’odierna collezione della Galleria Strossmayer è costituito dal lascito delle opere dei maestri antichi europei raccolti dal vescovo J.J. Strossmayer (1815-1905, il cui scopo fondamentale fu di allargare la tradizione culturale croata con l’appropriazione della cultura elitaria europea. Con il passare del tempo, il signifi cato e la funzione della Galleria cambiò considerevolmente. Prima della Prima guerra mondiale la Galleria Strossmayer fu un progetto utopistico nel senso che la sua missione non era solo di riempire il vuoto visto come il passato artistico mancante, ma anche di creare le fondamenta per una futura arte locale. Dopo la guerra, con la formazione del Regno dei Serbi, Croati e Sloveni, lo stato nazionale fu, almeno in un certo senso, realizzato, e

  10. Technical feasibility of a seabed gallery seawater intake at Ras Abu Ali Island, Arabian Gulf, Saudi Arabia

    KAUST Repository

    Rachman, Rinaldi

    2014-07-23

    (less than 1%) with porosity ranging between 0.29 and 0.41 and hydraulic conductivities up to 22.5 m3/d. It was determined that seabed gallery development is suitable at this location. Preliminary design for a seabed gallery filter was developed using a series of cells. Each gallery cell represents a unit that can be simply duplicated to meet the overall intake capacity requirement. Each gallery cell is designed to have minimum 8 m/d infiltration rate through five layers of engineered sand and gravel. The total thickness of the filter bed is 4.5 m (2 m top layer). The dimensions of the proposed cells are 100 × 30 m and each cell will conservatively provide 24,000 m3/d of filtered water. The design is flexible to meet the required capacity. For example, a SWRO desalination plant which produces 54,000 m3/d product water from 38,000 mg/L salinity seawater at a 45% conversion rate will require a minimum of 6 cells using the preliminary design. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  11. Walk, Look, Remember: The Influence of the Gallery's Spatial Layout on Human Memory for an Art Exhibition.

    Science.gov (United States)

    Krukar, Jakub

    2014-09-01

    The spatial organisation of museums and its influence on the visitor experience has been the subject of numerous studies. Previous research, despite reporting some actual behavioural correlates, rarely had the possibility to investigate the cognitive processes of the art viewers. In the museum context, where spatial layout is one of the most powerful curatorial tools available, attention and memory can be measured as a means of establishing whether or not the gallery fulfils its function as a space for contemplating art. In this exploratory experiment, 32 participants split into two groups explored an experimental, non-public exhibition and completed two unanticipated memory tests afterwards. The results show that some spatial characteristics of an exhibition can inhibit the recall of pictures and shift the focus to perceptual salience of the artworks.

  12. Temporal Dynamics and Resource Availability for Drosophilid Fruit Flies (Insecta, Diptera in a Gallery Forest in the Brazilian Savanna

    Directory of Open Access Journals (Sweden)

    Henrique Valadão

    2010-01-01

    Full Text Available Seasonality can cause severe bottlenecks in natural populations, even leading to local extinction. Large variation in resource availability may explain the bottlenecks, but the role of these variations is still poorly understood. The goal of this study was to analyze if temporal variations in the guild of drosophilids breeding in fruits of Mauritia flexuosa (Arecaceae can be explained by the shortage of this resource during the dry season. Fruits of M. flexuosa were collected over one year in a gallery forest located in the Central Brazilian Savanna. The drosophilid assemblage varied over time, with a lower density of species and of individuals in the dry season, when the percentage of colonized fruits was also smaller. These findings suggest that although the fruits were available during the dry season, they were underused. This way, the resource availability does not seem to regulate the community in the dry season.

  13. Visual events and the friendly eye: modes of educating vision in new educational settings in Danish art galleries

    DEFF Research Database (Denmark)

    Illeris, Helene

    2009-01-01

    in order to stimulate the ‘disciplined eye' or the ‘aesthetic eye' of the visitors, this article aims to discuss the practices of looking encouraged by contemporary and experimental educational projects. The first part of the article develops a theoretical perspective on educational settings conceived...... as visual events, and it discusses how ‘the desiring eye' of some constructivist approaches, along with traditional practices of looking, have contributed to the formation of the modern, autonomous individual. The second part of the article analyses two cases from Danish art galleries and, inspired by Mieke...... Bal, proposes the ‘friendly eye' as a possible dialogical and collective practice of looking that can be stimulated in educational settings....

  14. Plant food resources and the diet of a parrot community in a gallery forest of the southern Pantanal (Brazil

    Directory of Open Access Journals (Sweden)

    J. Ragusa-Netto

    Full Text Available Neotropical parrots usually forage in forest canopies for nectar, flowers, leaves, fruit pulp, and seeds. As they have no all-purpose territories, these birds usually exploit vegetation mosaics in order to use plentiful resources as they become available. In this study we examine the use of a gallery forest in the southern Pantanal (Brazil by a diverse parrot community that ranged from Brotogeris chiriri (a small species to Ara chloroptera (a large one. Plant food resources principally used by parrots were abundantly available during the rainy season (fleshy fruits, the annual floods (fleshy fruits, and the dry season (flowers. While both smaller and larger species foraged on fruits, parakeets largely consumed the pulp, while larger parrot species used pulp and seeds. In the dry season parakeets foraged extensively on nectar, especially Inga vera nectar that was abundantly available during the last two months of the dry season, the harshest period of the year. Among larger parrots, only Propyrrhura auricollis frequently harvested nectar. Fruits maturing during floods, despite being fish- or water- dispersed were extensively used by the parrots. Hence, unlike what happens in most other Neotropical dry forests, occurrence of a fruiting peak during the annual flooding, which occurs in the transition from the wet to the dry season, constitutes an extra and significant episode of food availability, since in this period, fruit production normally declines. Therefore, the unique and abundant availability of flowers and fruits in this gallery forest may account for the presence of large parrot populations in the southern Pantanal.

  15. Stand-Off Biodetection with Free-Space Coupled Asymmetric Microsphere Cavities

    Directory of Open Access Journals (Sweden)

    Zachary Ballard

    2015-04-01

    Full Text Available Asymmetric microsphere resonant cavities (ARCs allow for free-space coupling to high quality (Q whispering gallery modes (WGMs while exhibiting highly directional light emission, enabling WGM resonance measurements in the far-field. These remarkable characteristics make “stand-off” biodetection in which no coupling device is required in near-field contact with the resonator possible. Here we show asymmetric microsphere resonators fabricated from optical fibers which support dynamical tunneling to excite high-Q WGMs, and demonstrate free-space coupling to modes in an aqueous environment. We characterize the directional emission by fluorescence imaging, demonstrate coupled mode effects due to free space coupling by dynamical tunneling, and detect adsorption kinetics of a protein in aqueous solution. Based on our approach, new, more robust WGM biodetection schemes involving microfluidics and in-vivo measurements can be designed.

  16. High quality factor of AlN microdisks embedding GaN quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Mexis, M.; Guillet, T.; Brimont, C.; Bretagnon, T.; Gil, B. [GES, Universite des Sciences et Techniques du Languedoc, Place Eugene Bataillon, 34095 Montpellier (France); Sergent, S. [CHREA-CNRS, 06560 Valbonne (France); Universite de Nice Sophia Antipolis, Parc Valrose, 06102 Nice (France); Semond, F.; Leroux, M. [CHREA-CNRS, 06560 Valbonne (France); Neel, D.; David, S.; Checoury, X.; Boucaud, P. [Institut d' Electronique Fondamentale, CNRS - Universite Paris Sud, 91405 Orsay (France)

    2011-07-15

    We report the observation of high quality (Q) factor whispering gallery modes for GaN/AlN quantum dot based microdisks. Room temperature photoluminescence measurements show a large number of high Q modes on the whole PL spectral range. For the first time we report Q values up to 6000 for nitride based cavities. We attribute this improvement of the Q factor to the etching quality and to the relatively low cavity loss by inserting dots into the microdisks. The uniformity of the resonant modes with respect to a wide range of energies allows us to identify the different radial mode families. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. A Solid State Ultraviolet Lasers Based on Cerium-Doped LiCaAIF(sub 6) Crystal Resonator

    Science.gov (United States)

    Yu, Nan; Le, Thanh; Schowalter, Steven J.; Rellergert, Wade; Jeet, Justin; Lin, Guoping; Hudson, Eric

    2012-01-01

    We report the first demonstration of a UV laser using a high-Q whispering gallery mode (WGM) resonator of Ce+: LiCaAlF6. We show that WGM resonators from LiCaAlF6 can achieve a Q of 2.6 x 10(sup 7) at UV. We demonstrated a UV laser at 290 nm with a pulsed pump laser at 266 nm. The experiments showed the low pump threshold intensity of 7.5 x 10(sup 9) W/m(sup 2) and slope efficiency of 25%. We have also observed lasing delay dynamics. These results are consistent with our modeling and theoretical estimates, and pave the way for a low threshold cw UV laser using WGM resonator cavity.

  18. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON RHIC SPIN PHYSICS III AND IV, POLARIZED PARTONS AT HIGH Q2 REGION, AUGUST 3, 2000 AT BNL, OCTOBER 14, 2000 AT KYOTO UNIVERSITY.

    Energy Technology Data Exchange (ETDEWEB)

    BUNCE, G.; VIGDOR, S.

    2001-03-15

    International workshop on II Polarized Partons at High Q2 region 11 was held at the Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan on October 13-14, 2000, as a satellite of the international conference ''SPIN 2000'' (Osaka, Japan, October 16-21,2000). This workshop was supported by RIKEN (The Institute of Physical and Chemical Research) and by Yukawa Institute. The scientific program was focused on the upcoming polarized collider RHIC. The workshop was also an annual meeting of RHIC Spin Collaboration (RSC). The number of participants was 55, including 28 foreign visitors and 8 foreign-resident Japanese participants, reflecting the international nature of the RHIC spin program. At the workshop there were 25 oral presentations in four sessions, (1) RHIC Spin Commissioning, (2) Polarized Partons, Present and Future, (3) New Ideas on Polarization Phenomena, (4) Strategy for the Coming Spin Running. In (1) the successful polarized proton commissioning and the readiness of the accelerator for the physics program impressed us. In (2) and (3) active discussions were made on the new structure function to be firstly measured at RHIC, and several new theoretical ideas were presented. In session (4) we have established a plan for the beam time requirement toward the first collision of polarized protons. These proceedings include the transparencies presented at the workshop. The discussion on ''Strategy for the Coming Spin Running'' was summarized by the chairman of the session, S. Vigdor and G. Bunce.

  19. The Child Whisperer

    Science.gov (United States)

    Peters, Dane L.

    2012-01-01

    Unquestionably, Maria Montessori's insights into child development were both innate and learned, derived from her many years of working with children. Her work, practices, philosophy, and passion have staying power that, so far, spans a century and are a testament to her dedication and abilities. In this article, the author explains why he sees…

  20. Type specimens of Mollusca described by Col. George Montagu in the Royal Albert Memorial Museum & Art Gallery, Exeter and The Natural History Museum, London

    Directory of Open Access Journals (Sweden)

    P. Graham Oliver

    2017-11-01

    Full Text Available A complete list of new molluscan taxa introduced by Col. George Montagu (1753–1815 is presented. The available type material of these taxa are itemised and illustrated. The majority are present in the Royal Albert Memorial Museum & Art Gallery, Exeter with a smaller number in the Natural History Museum, London. The historic background of both collections is reviewed with special reference to the many non-British species spuriously introduced into Testacea Britannica and its Supplement.