Physics. Creating and probing electron whispering-gallery modes in graphene.

PubMed

Zhao, Yue; Wyrick, Jonathan; Natterer, Fabian D; Rodriguez-Nieva, Joaquin F; Lewandowski, Cyprian; Watanabe, Kenji; Taniguchi, Takashi; Levitov, Leonid S; Zhitenev, Nikolai B; Stroscio, Joseph A

2015-05-08

The design of high-finesse resonant cavities for electronic waves faces challenges due to short electron coherence lengths in solids. Complementing previous approaches to confine electronic waves by carefully positioned adatoms at clean metallic surfaces, we demonstrate an approach inspired by the peculiar acoustic phenomena in whispering galleries. Taking advantage of graphene's gate-tunable light-like carriers, we create whispering-gallery mode (WGM) resonators defined by circular pn junctions, induced by a scanning tunneling probe. We can tune the resonator size and the carrier concentration under the probe in a back-gated graphene device over a wide range. The WGM-type confinement and associated resonances are a new addition to the quantum electron-optics toolbox, paving the way to develop electronic lenses and resonators. Copyright © 2015, American Association for the Advancement of Science.

Development of optical WGM resonators for biosensors

NASA Astrophysics Data System (ADS)

Brice, I.; Pirktina, A.; Ubele, A.; Grundsteins, K.; Atvars, A.; Viter, R.; Alnis, J.

2017-12-01

Whispering Gallery Mode (WGM) resonators are very sensitive to nanoparticles attaching to the surface. We simulate this process using COMSOL Wave Optics module. Our spherical WGM resonators are produced by melting a tip of an optical fiber and we measure optical Q factors in the 105 range. Molecular oxygen lines of the air in the 760 nm region are used as reference markers when looking for the shifts of the WGM resonance lines. We demonstrate WGM microresonator surface coating with a layer of ZnO nanorods as well as with polystyrene microspheres. Coatings produce increased contact surface. Additional layer of antigens/antibodies will be coated to make high-specificity biosensors.

Selective Coupling Enhances Harmonic Generation of Whispering-Gallery Modes

NASA Astrophysics Data System (ADS)

Trainor, Luke S.; Sedlmeir, Florian; Peuntinger, Christian; Schwefel, Harald G. L.

2018-02-01

We demonstrate second-harmonic generation (SHG) in an x -cut congruent lithium niobate (LN) whispering-gallery mode (WGM) resonator. First, we show theoretically that independent control of the coupling of the pump and signal modes is optimal for high conversion rates. A coupling scheme based on our earlier work [F. Sedlmeir et al., Phys. Rev. Applied 7, 024029 (2017), 10.1103/PhysRevApplied.7.024029] is then implemented experimentally to verify this improvement. Thereby, we are able to improve on the efficiency of SHG by more than an order of magnitude by selectively outcoupling using a LN prism, utilizing the birefringence of it and the resonator in kind. This method is also applicable to other nonlinear processes in WGM resonators.

Quantification of whispering gallery mode spectrum variability in application to sensing nanobiophotonics

NASA Astrophysics Data System (ADS)

Saetchnikov, Anton; Skakun, Victor; Saetchnikov, Vladimir; Tcherniavskaia, Elina; Ostendorf, Andreas

2017-10-01

An approach for the automated whispering gallery mode (WGM) signal decomposition and its parameter estimation is discussed. The algorithm is based on the peak picking and can be applied for the preprocessing of the raw signal acquired from the multiplied WGM-based biosensing chips. Quantitative estimations representing physically meaningful parameters of the external disturbing factors on the WGM spectral shape are the output values. Derived parameters can be directly applied to the further deep qualitative and quantitative interpretations of the sensed disturbing factors. The algorithm is tested on both simulated and experimental data taken from the bovine serum albumin biosensing task. The proposed solution is expected to be a useful contribution to the preprocessing phase of the complete data analysis engine and is expected to push the WGM technology toward the real-live sensing nanobiophotonics.

Few-Mode Whispering-Gallery-Mode Resonators

NASA Technical Reports Server (NTRS)

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

2006-01-01

Whispering-gallery-mode (WGM) optical resonators of a type now under development are designed to support few well-defined waveguide modes. In the simplest case, a resonator of this type would support one equatorial family of WGMs; in a more complex case, such a resonator would be made to support two, three, or some other specified finite number of modes. Such a resonator can be made of almost any transparent material commonly used in optics. The nature of the supported modes does not depend on which material is used, and the geometrical dispersion of this resonator is much smaller than that of a typical prior WGM resonator. Moreover, in principle, many such resonators could be fabricated as integral parts of a single chip. Basically, a resonator of this type consists of a rod, made of a suitable transparent material, from which protrudes a thin circumferential belt of the same material. The belt is integral with the rest of the rod (see figure) and acts as a circumferential waveguide. If the depth (d) and width (w) of the belt are made appropriately small, then the belt acts as though it were the core of a single-mode optical fiber: the belt and its adjacent supporting rod material support a single, circumferentially propagating mode or family of modes. It has been shown theoretically that the fiber-optic-like behavior of the belton- rod resonator structure can be summarized, in part, by the difference, Dn, between (1) an effective index of refraction of an imaginary fiber core and (2) the index of refraction (n) of the transparent rod/belt material. It has also been shown theoretically that for a given required value of Dn, the required depth of the belt can be estimated as d R Dn, where R is the radius of the rod. It must be emphasized that this estimated depth is independent of n and, hence, is independent of the choice of rod material. As in the cases of prior WGM resonators, input/output optical coupling involves utilization of evanescent fields. In the

Vertically-coupled Whispering Gallery Mode Resonator Optical Waveguide, and Methods

NASA Technical Reports Server (NTRS)

Matsko, Andrey B. (Inventor); Savchenkov, Anatolly A. (Inventor); Matleki, Lute (Inventor)

2007-01-01

A vertically-coupled whispering gallery mode (WGM) resonator optical waveguide, a method of reducing a group velocity of light, and a method of making a waveguide are provided. The vertically-coupled WGM waveguide comprises a cylindrical rod portion having a round cross-section and an outer surface. First and second ring-shaped resonators are formed on the outer surface of the cylindrical rod portion and are spaced from each other along a longitudinal direction of the cylindrical rod. The first and second ringshaped resonators are capable of being coupled to each other by way an evanescent field formed in an interior of the cylindrical rod portion.

Whispering-Gallery-Mode Resonances: A New Way to Accelerate Charged Particles

NASA Astrophysics Data System (ADS)

Żakowicz, Władysław

2005-09-01

Looking for future high energy accelerators we point at a very strong interaction between relativistic electrons and powerful electromagnetic fields existing in the vicinity of a dielectric cylinder in conditions of resonantly excited whispering gallery modes (WGM). A particular example of the WGM resonance, corresponding to angular index n=22, shows that the accelerating fields are almost 100 times stronger than these in the incident wave. That yields an acceleration rate of about 5GeV/m with the incident microwave radiation beam of the wavelength λ=1cm and a moderately high intensity of P=1MW/cm2.

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

NASA Astrophysics Data System (ADS)

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.

Nanoscale welding aerosol sensing based on whispering gallery modes in a cylindrical silica resonator.

PubMed

Lee, Aram; Mills, Thomas; Xu, Yong

2015-03-23

We report an experimental technique where one uses a standard silica fiber as a cylindrical whispering gallery mode (WGM) resonator to sense airborne nanoscale aerosols produced by electric arc welding. We find that the accumulation of aerosols on the resonator surface induces a measurable red-shift in resonance frequency, and establish an empirical relation that links the magnitude of resonance shift with the amount of aerosol deposition. The WGM quality factors, by contrast, do not decrease significantly, even for samples with a large percentage of surface area covered by aerosols. Our experimental results are discussed and compared with existing literature on WGM-based nanoparticle sensing.

Sensitivity optimization in whispering gallery mode optical cylindrical biosensors

NASA Astrophysics Data System (ADS)

Khozeymeh, F.; Razaghi, M.

2018-01-01

Whispering-gallery-mode resonances propagated in cylindrical resonators have two angular and radial orders of l and i. In this work, the higher radial order whispering-gallery-mode resonances, (i = 1 - 4), at a fixed l are examined. The sensitivity of theses resonances is analysed as a function of the structural parameters of the cylindrical resonator like different radii and refractive index of composed material of the resonator. A practical application where cylindrical resonators are used for the measurement of glucose concentration in water is presented as a biosensor demonstrator. We calculate the wavelength shifts of the WG1-4, in several glucose/water solutions, with concentrations spanning from 0.0% to 9.0.% (weight/weight). Improved sensitivity can be achieved using multi-WGM cylindrical resonators with radius of R = 100 μm and resonator composed material of MgF 2 with refractive index of nc = 1.38. Also the effect of polarization on sensitivity is considered for all four WGMs. The best sensitivity of 83.07 nm/RIU for the fourth WGM with transverse magnetic polarization, is reported. These results propose optimized parameters aimed to fast designing of cylindrical resonators as optical biosensors, where both the sensitivity and the geometries can be optimized.

WGM Resonators for Terahertz-to-Optical Frequency Conversion

NASA Technical Reports Server (NTRS)

Strekalov,Dmitry; Savchenkov, Anatoliy; Matsko, Andrey; Nu, Nan

2008-01-01

Progress has been made toward solving some practical problems in the implementation of terahertz-to-optical frequency converters utilizing whispering-gallery-mode (WGM) resonators. Such frequency converters are expected to be essential parts of non-cryogenic terahertz- radiation receivers that are, variously, under development or contemplated for a variety of applications in airborne and spaceborne instrumentation for astronomical and military uses. In most respects, the basic principles of terahertz-to-optical frequency conversion in WGM resonators are the same as those of microwave (sub-terahertz)-to-optical frequency conversion in WGM resonators, various aspects of which were discussed in the three preceeding articles. To recapitulate: In a receiver following this approach, a preamplified incoming microwave signal (in the present case, a terahertz signal) is up-converted to an optical signal by a technique that exploits the nonlinearity of the electromagnetic response of a whispering-gallery-mode (WGM) resonator made of LiNbO3 or another suitable electro-optical material. Upconversion takes place by three-wave mixing in the resonator. To ensure the required interaction among the optical and terahertz signals, the WGM resonator must be designed and fabricated to function as an electro-optical modulator while simultaneously exhibiting (1) resonance at the required microwave and optical operating frequencies and (2) phase matching among the microwave and optical signals circulating in the resonator. Downstream of the WGM resonator, the up-converted signal is processed photonically by use of a tunable optical filter or local oscillator and is then detected. The practical problems addressed in the present development effort are the following: Satisfaction of the optical and terahertz resonance-frequency requirement is a straightforward matter, inasmuch as the optical and terahertz spectra can be measured. However, satisfaction of the phase-matching requirement is

White-Light Whispering Gallery Mode Optical Resonator System and Method

NASA Technical Reports Server (NTRS)

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

Self-assembled dye-doped polymer microspheres as whispering gallery mode lasers

NASA Astrophysics Data System (ADS)

Chen, Xiaogang; Sun, Hongyi; Yang, Hongqin; Wu, Xiang; Xie, Shusen

2016-10-01

Microlasers based on high-Q whispering-gallery-mode (WGM) resonances are promising low-threshold laser sources for bio-sensing and imaging applications. In this talk, we demonstrate a cost effective approach to obtain size-controllable polymer microspheres, which can be served as good WGM microcavities. By injecting SU-8 solution into low-refractiveindex UV polymer, self-assembled spherical droplet with smooth surface can be created inside the elastic medium and then solidified by UV exposure. The size of the microspheres can be tuned from several to hundreds of microns. WGM Lasing has been achieved by optically pumping the dye-doped microspheres with ns lasers. Experimental results show that the microsphere lasers have high quality factors and low lasing thresholds. The self-assembled dye-doped polymer microspheres would provide an excellent platform for the micro-laser sources in on-chip biosensing and imaging systems.

White-Light Whispering-Gallery-Mode Optical Resonators

NASA Technical Reports Server (NTRS)

Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

2006-01-01

Whispering-gallery-mode (WGM) optical resonators can be designed to exhibit continuous spectra over wide wavelength bands (in effect, white-light spectra), with ultrahigh values of the resonance quality factor (Q) that are nearly independent of frequency. White-light WGM resonators have potential as superior alternatives to (1) larger, conventional optical resonators in ring-down spectroscopy, and (2) optical-resonator/electro-optical-modulator structures used in coupling of microwave and optical signals in atomic clocks. In these and other potential applications, the use of white-light WGM resonators makes it possible to relax the requirement of high-frequency stability of lasers, thereby enabling the use of cheaper lasers. In designing a white-light WGM resonator, one exploits the fact that the density of the mode spectrum increases predictably with the thickness of the resonator disk. By making the resonator disk sufficiently thick, one can make the frequency differences between adjacent modes significantly less than the spectral width of a single mode, so that the spectral peaks of adjacent modes overlap, making the resonator spectrum essentially continuous. Moreover, inasmuch as the Q values of the various modes are determined primarily by surface Rayleigh scattering that does not depend on mode numbers, all the modes have nearly equal Q. By use of a proper coupling technique, one can ensure excitation of a majority of the modes. For an experimental demonstration of a white-light WGM resonator, a resonator disk 0.5-mm thick and 5 mm in diameter was made from CaF2. The shape of the resonator and the fiberoptic coupling arrangement were as shown in Figure 1. The resonator was excited with laser light having a wavelength of 1,320 nm and a spectral width of 4 kHz. The coupling efficiency exceeded 80 percent at any frequency to which the laser could be set in its tuning range, which was >100-GHz wide. The resonator response was characterized by means of ring

Mode-splitting for refractive index sensing in fluorescent whispering gallery mode resonators with broken symmetry

NASA Astrophysics Data System (ADS)

Kang, Yvonne Q.; François, Alexandre; Riesen, Nicolas; Monro, Tanya M.

2018-02-01

Whispering Gallery Mode (WGM) biosensors have been widely exploited over the past decade, owing to their unprecedented detection limits and label free capability. WGM based sensing mechanisms, such as resonance frequency shift, linewidth broadening, and splitting of the two counter-propagating WGMs, have been extensively researched and applied for bio-chemical sensing. However, the mode-splitting of the originally degenerate WGMs from different equatorial planes on a fluorescent microsphere has not been fully investigated. In this work, we break the symmetry of the surrounding environment outside the microsphere by partially embedding the sphere into a high-refractive-index medium (i.e. glue), to lift the degeneracy of the modes from different WGM planes. The split-modes from multiple planes of the fluorescent microsphere are indiscriminately collected. It is found that the effective quality factor Q of the WGMs increases non-conventionally as the Refractive Index (RI) of the probing liquid increases up to the point where it is equal to that of the glue. This presents a new methodology for quantifying changes in the probing environment based on the Q spoiling of the resonances as determined by the RI difference between the environment and that of the reference glue. Furthermore, we find that this sensing platform opens the door to simple self-referenced sensing techniques based on the analysis of the spectral positions of subsets of the split modes.

Comparison of raised-microdisk whispering-gallery-mode characterization techniques.

PubMed

Redding, Brandon; Marchena, Elton; Creazzo, Tim; Shi, Shouyuan; Prather, Dennis W

2010-04-01

We compare the two prevailing raised-microdisk whispering-gallery-mode (WGM) characterization techniques, one based on coupling emission to a tapered fiber and the other based on collecting emission in the far field. We applied both techniques to study WGMs in Si nanocrystal raised microdisks and observed dramatically different behavior. We explain this difference in terms of the radiative bending loss on which the far-field collection technique relies and discuss the regimes of operation in which each technique is appropriate.

Electrically tunable whispering gallery mode microresonator based on a grapefruit-microstructured optical fiber infiltrated with nematic liquid crystals.

PubMed

Yang, Chengkun; Zhang, Hao; Liu, Bo; Lin, Shiwei; Li, Yuetao; Liu, Haifeng

2017-08-01

An electrically tunable whispering gallery mode (WGM) microresonator based on an HF-etched microstructured optical fiber (MOF) infiltrated with nematic liquid crystals (NLCs) is proposed and experimentally demonstrated. Experimental results indicate that as the peak-to-peak voltage of the applied AC electric field increases from 160 to 220 V, WGM resonance peaks gradually move toward a shorter wavelength region by 0.527 nm with a wavelength sensitivity up to 0.01  nm/V for a TM1691 mode, and the Q-factor for each WGM resonance peak rapidly decreases with the increment of applied electric voltage. The proposed electrically controlled WGM tuning scheme shows a linear resonance wavelength shift with good spectral reversibility, which makes it a promising candidate to serve as an integrated functional photonic device in practical use and in related fundamental scientific studies.

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

NASA Astrophysics Data System (ADS)

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.

WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

NASA Technical Reports Server (NTRS)

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

2007-01-01

Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids. These sensor optics exploit the properties of a special class of non-diffracting light beams that are denoted Bessel beams because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have large values of angular momentum. In a sensor optic of this type, a low-profile WGM resonator that supports modes having large angular momenta is used to generate high-order Bessel beams. As used here, "low-profile" signifies that the WGM resonator is an integral part of the rod optical waveguide but has a radius slightly different from that of the adjacent part(s).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushida, Soh; Yamamoto, Yohei; Braam, Daniel

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.

Biosensing by WGM Microspherical Resonators

PubMed Central

Righini, Giancarlo C.; Soria, Silvia

2016-01-01

Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 108–109 lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

Preventing Raman Lasing in High-Q WGM Resonators

NASA Technical Reports Server (NTRS)

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

2007-01-01

A generic design has been conceived to suppress the Raman effect in whispering- gallery-mode (WGM) optical resonators that have high values of the resonance quality factor (Q). Although it is possible to exploit the Raman effect (even striving to maximize the Raman gain to obtain Raman lasing), the present innovation is intended to satisfy a need that arises in applications in which the Raman effect inhibits the realization of the full potential of WGM resonators as frequency-selection components. Heretofore, in such applications, it has been necessary to operate high-Q WGM resonators at unattractively low power levels to prevent Raman lasing. (The Raman-lasing thresholds of WGM optical resonators are very low and are approximately proportional to Q(sup -2)). Heretofore, two ways of preventing Raman lasting at high power levels have been known, but both entail significant disadvantages: A resonator can be designed so that the optical field is spread over a relatively large mode volume to bring the power density below the threshold. For any given combination of Q and power level, there is certain mode volume wherein Raman lasing does not start. Unfortunately, a resonator that has a large mode volume also has a high spectral density, which is undesirable in a typical photonic application. A resonator can be cooled to the temperature of liquid helium, where the Raman spectrum is narrower and, therefore, the Raman gain is lower. However, liquid-helium cooling is inconvenient. The present design overcomes these disadvantages, making it possible to operate a low-spectral-density (even a single-mode) WGM resonator at a relatively high power level at room temperature, without risk of Raman lasing.

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

NASA Astrophysics Data System (ADS)

Itobe, Hiroki; Nakagawa, Yosuke; Mizumoto, Yuta; Kangawa, Hiroi; Kakinuma, Yasuhiro; Tanabe, Takasumi

2016-05-01

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.

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

PubMed Central

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

2016-01-01

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. PMID:27153099

Infrared light detection using a whispering-gallery-mode optical microcavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jiangang, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu; Ozdemir, Sahin Kaya, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu; Yang, Lan, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu

2014-04-28

We demonstrate a thermal infrared (IR) detector based on an ultra-high-quality-factor (Q) whispering-gallery-mode (WGM) microtoroidal silica resonator and investigate its performance to detect IR radiation at 10 μm wavelength. The bandwidth and the sensitivity of the detector are dependent on the power of a probe laser and the detuning between the probe laser and the resonance frequency of the resonator. The microtoroid IR sensor achieved a noise-equivalent-power (NEP) of 7.46 nW, corresponding to an IR intensity of 0.095 mW/cm{sup 2}.

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

PubMed

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.

WGM-Based Photonic Local Oscillators and Modulators

NASA Technical Reports Server (NTRS)

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

2007-01-01

Photonic local oscillators and modulators that include whispering-gallery mode (WGM) optical resonators have been proposed as power-efficient devices for generating and detecting radiation at frequencies of the order of a terahertz. These devices are intended especially to satisfy anticipated needs for receivers capable of detecting lowpower, narrow-band terahertz signals to be used for sensing substances of interest in scientific and military applications. At present, available terahertz-signal detectors are power-inefficient and do not afford the spectral and amplitude resolution needed for detecting such signals. The proposed devices would not be designed according to the conventional approach of direct detection of terahertz radiation. Instead, terahertz radiation would first be up-converted into the optical domain, wherein signals could be processed efficiently by photonic means and detected by optical photodetectors, which are more efficient than are photodetectors used in conventional direct detection of terahertz radiation. The photonic devices used to effect the up-conversion would include a tunable optical local oscillator and a novel electro-optical modulator. A local oscillator according to the proposal would be a WGM-based modelocked laser operating at a desired pulserepetition rate of the order of a terahertz. The oscillator would include a terahertz optical filter based on a WGM microresonator, a fiber-optic delay line, an optical amplifier (which could be either a semiconductor optical amplifier or an erbium-doped optical fiberamplifier), and a WGM Ka-band modulator. The terahertz repetition rate would be obtained through harmonic mode locking: for example, by modulating the light at a frequency of 33 GHz and locking each 33d optical mode, one would create a 1.089-THz pulse train. The high resonance quality factors (Q values) of WGM optical resonators should make it possible to decrease signal-generation threshold power levels significantly below

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

PubMed Central

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

Whispering gallery mode resonators for rapid label-free biosensing in small volume droplets.

PubMed

Wildgen, Sarah M; Dunn, Robert C

2015-03-23

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.

New spherical optical cavities with non-degenerated whispering gallery modes

NASA Astrophysics Data System (ADS)

Kumagai, Tsutaru; Palma, Giuseppe; Prudenzano, Francesco; Kishi, Tetsuo; Yano, Tetsuji

2017-02-01

New spherical resonators with internal defects are introduced to show anomalous whispering gallery modes (WGMs). The defect induces a symmetry breaking spherical cavity and splits the WGMs. A couple of defects, a hollow sphere (bubble), and a hollow ring, have been studied. The hollow sphere was fabricated and the splitting of WGM was observed. In this paper, this "non-degenerated WGMs (non-DWGMs) resonance" in a microsphere with hollow defect structure is reviewed based on our research. The resonance of WGMs in a sphere is identified by three integer parameters: the angular mode number, l, azimuthal mode number m, and radial mode number, n. The placement of the defect such as a hollow ring or single bubble is shown to break symmetry and resolve the degeneracy concerning m. This induces a variety of resonant wavelengths of the spherical cavity. A couple of simulations using the eigenmode and transient analyses propose how the placed defects affect the WGM resonance in the spherical cavity. For the sphere with a single bubble defect, the experimentally observed resonances in Nd-doped tellurite glass microsphere with a single bubble are clarified to be due to the splitting of resonance modes, i.e., the existence of "non-DWGMs" in the sphere. The defect bubble plays a role of opening the optically wide gate to introduce excitation light for Nd3+ pumping using non-DWGMs in the sphere efficiently.

SERS-active ZnO/Ag hybrid WGM microcavity for ultrasensitive dopamine detection

NASA Astrophysics Data System (ADS)

Lu, Junfeng; Xu, Chunxiang; Nan, Haiyan; Zhu, Qiuxiang; Qin, Feifei; Manohari, A. Gowri; Wei, Ming; Zhu, Zhu; Shi, Zengliang; Ni, Zhenhua

2016-08-01

Dopamine (DA) is a potential neuro modulator in the brain which influences a variety of motivated behaviors and plays a key role in life science. A hybrid ZnO/Ag microcavity based on Whispering Gallery Mode (WGM) effect has been developed for ultrasensitive detection of dopamine. Utilizing this effect of structural cavity mode, a Raman signal of R6G (5 × 10-3 M) detected by this designed surface-enhanced Raman spectroscopy (SERS)-active substrate was enhanced more than 10-fold compared with that of ZnO film/Ag substrate. Also, this hybrid microcavity substrate manifests high SERS sensitivity to rhodamine 6 G and detection limit as low as 10-12 M to DA. The Localized Surface Plasmons of Ag nanoparticles and WGM-enhanced light-matter interaction mainly contribute to the high SERS sensitivity and help to achieve a lower detection limit. This designed SERS-active substrate based on the WGM effect has the potential for detecting neurotransmitters in life science.

Using Whispering-Gallery-Mode Resonators for Refractometry

NASA Technical Reports Server (NTRS)

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

Percolation of light through whispering gallery modes in 3D lattices of coupled microspheres.

PubMed

Astratov, Vasily N; Ashili, Shashanka P

2007-12-10

Using techniques of flow-assisted self-assembly we synthesized three-dimensional (3D) lattices of dye-doped fluorescent (FL) 5 mum polystyrene spheres with 3% size dispersion with well controlled thickness from one monolayer up to 43 monolayers. In FL transmission spectra of such lattices we observed signatures of coupling between multiple spheres with nearly resonant whispering gallery modes (WGMs). These include (i) splitting of the WGM-related peaks with the magnitude 4.0-5.3 nm at the average wavelength 535 nm, (ii) pump dependence of FL transmission showing that the splitting is seen only above the threshold for lasing WGMs, and (iii) anomalously high transmission at the WGM peak wavelengths compared to the background for samples with thickness around 25 mum. We propose a qualitative interpretation of the observed WGM transport based on an analogy with percolation theory where the sites of the lattice (spheres) are connected with optical "bonds" which are present with probability depending on the spheres' size dispersion. We predict that the WGM percolation threshold should be achievable in close packed 3D lattices formed by cavities with ~10(3) quality factors of WGMs and with ~1% size dispersion. Such systems can be used for developing next generation of resonant sensors and arrayed-resonator light emitting devices.

Squeezing Alters Frequency Tuning of WGM Optical Resonator

NASA Technical Reports Server (NTRS)

Mohageg, Makan; Maleki, Lute

2010-01-01

Mechanical squeezing has been found to alter the frequency tuning of a whispering-gallery-mode (WGM) optical resonator that has an elliptical shape and is made of lithium niobate. It may be possible to exploit this effect to design reconfigurable optical filters for optical communications and for scientific experiments involving quantum electrodynamics. Some background information is prerequisite to a meaningful description of the squeezing-induced alteration of frequency tuning: The spectrum of a WGM resonator is represented by a comblike plot of intensity versus frequency. Each peak of the comblike plot corresponds to an electromagnetic mode represented by an integer mode number, and the modes are grouped into sets represented by integer mode indices. Because lithium niobate is an electro-optically active material, the WGM resonator can be tuned (that is, the resonance frequencies can be shifted) by applying a suitable bias potential. The frequency shift of each mode is quantified by a tuning rate defined as the ratio between the frequency shift and the applied potential. In the absence of squeezing, all modes exhibit the same tuning rate. This concludes the background information. It has been demonstrated experimentally that when the resonator is squeezed along part of either of its two principal axes, tuning rates differ among the groups of modes represented by different indices (see figure). The differences in tuning rates could be utilized to configure the resonance spectrum to obtain a desired effect; for example, through a combination of squeezing and electrical biasing, two resonances represented by different mode indices could be set at a specified frequency difference something that could not be done through electrical biasing alone.

Spectrum Analyzers Incorporating Tunable WGM Resonators

NASA Technical Reports Server (NTRS)

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

2009-01-01

A photonic instrument is proposed to boost the resolution for ultraviolet/ optical/infrared spectral analysis and spectral imaging allowing the detection of narrow (0.00007-to-0.07-picometer wavelength resolution range) optical spectral signatures of chemical elements in space and planetary atmospheres. The idea underlying the proposal is to exploit the advantageous spectral characteristics of whispering-gallery-mode (WGM) resonators to obtain spectral resolutions at least three orders of magnitude greater than those of optical spectrum analyzers now in use. Such high resolutions would enable measurement of spectral features that could not be resolved by prior instruments.

Whispering gallery mode resonators for frequency metrology applications

NASA Astrophysics Data System (ADS)

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

Microwave-to-Optical Conversion in WGM Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Strekalov, Dmitry; Yu, Nan; Matsko, Andrey; Maleki, Lute

2008-01-01

Microwave-to-optical frequency converters based on whispering-gallery-mode (WGM) resonators have been proposed as mixers for the input ends of microwave receivers in which, downstream of the input ends, signals would be processed photonically. A frequency converter as proposed (see figure) would exploit the nonlinearity of the electromagnetic response of a WGM resonator made of LiNbO3 or another suitable ferroelectric material. Up-conversion would take place by three-wave mixing in the resonator. The WGM resonator would be de - signed and fabricated to obtain (1) resonance at both the microwave and the optical operating frequencies and (2) phase matching among the input and output microwave and optical signals as described in the immediately preceding article. Because the resonator would be all dielectric there would be no metal electrodes signal losses would be very low and, consequently, the resonance quality factors (Q values) of the microwave and optical fields would be very large. The long lifetimes associated with the large Q values would enable attainment of high efficiency of nonlinear interaction with low saturation power. It is anticipated that efficiency would be especially well enhanced by the combination of optical and microwave resonances in operation at input signal frequencies between 90 and 300 GHz.

Study of NTA-Nickel (II) Motif Functionalization for Binding of Histidine-Tagged Proteins by a Whispering Gallery Mode Resonator

NASA Astrophysics Data System (ADS)

Khuong, Anne Chudolij

This work demonstrates the viability of the whispering gallery mode (WGM) photonic sensing method for use as a biosensor by demonstrating a surface immobilization strategy for histidine tagged biomolecules to the WGM sensor surface. The WGM resonator is a dielectric spherical microstructure that can sustain high-Q electromagnetic waves confined to the sphere by total internal reflection. Light circumnavigates the periphery of the WGM resonator and when the trapped light constructively superimposes onto itself on the round trip, a resonance condition is achieved. Because of minimal loss due to reflection, these modes can reach unusually high quality factors. When a change occurs in the evanescent field at the boundary of the resonator and surrounding environment, such as when a molecule binds to the resonator surface, a shift results in the resonance wavelength; this enables the WGM resonator to be used as a sensor. WGM optical biosensors offer a powerful alternative to conventional analytical techniques due to their high sensitivity, specificity and their ability to directly detect label-free events in real time. There has been considerable growth in this field over the last decade and potential applications to medical and biotechnological research are numerous; however, there are still obstacles limiting the widespread commercial use of these devices. The obstacle we address in this work relates to a general fundamental difficulty incorporating biomaterial into biosensors. We demonstrate a specific and controlled functionalization strategy intended for subsequent assimilation of biomolecules onto the WGM resonator surface. We have developed a general method which can be used to controllably immobilize recombinant proteins to WGM silica surfaces via their histidine tags. In the work presented herein we monitor by WGM, in real time, a two step functionalization strategy to incorporate an NTA-Ni2+ motif onto the surface of a WGM resonator. We estimated the

Phase-Array Approach to Optical Whispering Gallery Modulators

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry

2010-01-01

This technology leverages the well-defined orbital number of a whispering gallery modulator (WGM) to expand the range of applications for such resonators. This property rigidly connects the phase variation of the field in this mode with the azimuthal angle between the coupling locations. A WGM with orbital momentum L has exactly L instant nodes around the circumference of the WGM resonator supporting such a mode. Therefore, in two locations separated by the arc alpha, the phase difference of such a field will be equal to phi= alpha L. Coupling the field out of such locations, and into a balanced interferometer, once can observe a complete constructive or distractive interference (or have any situation in between) depending on the angle alpha. Similarly, a mode L + delta L will pick up the phase phi + alpha delta L. In all applications of a WGM resonator as a modulator, the orbital numbers for the carrier and sidebands are different, and their differences delta L are known (usually, but not necessarily, delta L = 1). Therefore, the choice of the angle alpha, and of the interferometer arms difference, allows one to control the relative phase between different modes and to perform the conversion, separation, and filtering tasks necessary.

Microoptical device for efficient read-out of active WGM resonators

NASA Astrophysics Data System (ADS)

Wienhold, Tobias; Brammer, Marko; Grossmann, Tobias; Schneider, Marc; Kalt, Heinz; Mappes, Timo

2012-06-01

Whispering-gallery mode (WGM) resonators are known to offer outstanding properties for applications in photonics and telecommunication. Despite their promising performance, one major obstacle for the use of WGM resonators in industrial products is the need of expensive components and high-precision setups for their operation, requiring a controlled lab environment. For industrial applications technically simpler and more robust realizations are desired. Active WGM resonators utilize an optical gain medium for light amplification within the resonator and may be operated as lasers. They offer several advantages over their passive counterparts, such as cheap pump sources, free space excitation of resonator modes, and potentially narrower line widths. However, collection of the light emitted from the resonator still bears several challenges. Emission occurs in plane of the resonator and radiation is emitted isotropically along the circumference. Thus, detectors positioned in plane of the resonator may collect only a limited angular segment of the resonator's light emission. We report on a microoptical device which is integrated on the resonator chip and redirects all in-plane emission of active WGM resonators into a defined off-plane direction. Redirected light can easily be collected using a standard detector. Contrary to other approaches our microoptical device does not decrease the quality factor (Q factor) of the resonator. As light from all angular segments of the resonator is collected, the detected signal-to-noise ratio is expected to be largely improved. Our microoptical device therefore offers a promising approach towards mass-producible integration of active WGM resonators, e. g. into a Lab-on-a-Chip, for sensor applications, where smallest possible frequency shifts need to be read out by a highly sensitive detector.

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

PubMed

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.

Calligraphic Poling for WGM Resonators

NASA Technical Reports Server (NTRS)

Mohageg, Makan; Strekalov, Dmitry; Savchenkov, Anatoliy; Matsko, Andrey; Ilchenko, Vladimir; Maleki, Lute

2007-01-01

By engineering the geometry of a nonlinear optical crystal, the effective efficiency of all nonlinear optical oscillations can be increased dramatically. Specifically, sphere and disk shaped crystal resonators have been used to demonstrate nonlinear optical oscillations at sub-milliwatt input power when cs light propagates in a Whispering Gallery Mode (WGM) of such a resonant cavity. in terms of both device production and experimentation in quantum optics, some nonlinear optical effects with naturally high efficiency can occult the desired nonlinear scattering process. the structure to the crystal resonator. In this paper, I will discuss a new method for generating poling structures in ferroelectric crystal resonators called calligraphic poling. The details of the poling apparatus, experimental results and speculation on future applications will be discussed.

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

PubMed

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.

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

PubMed

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.

Whispering-gallery-mode-based seismometer

DOEpatents

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.

Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators

NASA Technical Reports Server (NTRS)

Anderson, Mark S.

2013-01-01

The motivation of this work was to have robust spectroscopic sensors for sensitive detection and chemical analysis of organic and molecular compounds. The solution is to use silica sphere optical resonators to provide surface-enhanced spectroscopic signal. Whispering-gallery mode (WGM) resonators made from silica microspheres were used for surface-enhanced Raman scattering (SERS) without coupling to a plasmonic mechanism. Large Raman signal enhancement is observed by exclusively using 5.08-micron silica spheres with 785-nm laser excitation. The advantage of this non-plasmonic approach is that the active substrate is chemically inert silica, thermally stable, and relatively simple to fabricate. The Raman signal enhancement is broadly applicable to a wide range of molecular functional groups including aliphatic hydrocarbons, siloxanes, and esters. Applications include trace organic analysis, particularly for in situ planetary instruments that require robust sensors with consistent response.

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

PubMed

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.

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

PubMed Central

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

2016-01-01

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 Hg2+ 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. PMID:27483277

Ringing phenomenon in coupled cavities: Application to modal coupling in whispering-gallery-mode resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trebaol, Stephane; Dumeige, Yannick; Feron, Patrice

We present a simple model to describe the transient response of two coupled resonators probed by a monochromatic wave whose frequency is rapidly swept across the resonances with respect to their characteristic photon lifetimes. The model is applied to analyze the dynamic behavior of the modal coupling between two degenerate resonances of the same cavity. In particular, this can be used to describe the coupling of counterpropagating whispering gallery modes (WGMs) by Rayleigh scattering. The theory is successfully compared to experiments carried out in silica microspheres. These results show that this ringdown technique can be extended to accurately measure linearmore » properties and frequency splittings of high-quality factor WGM microresonators.« less

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

NASA Astrophysics Data System (ADS)

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.

The Role of Transport Phenomena in Whispering Gallery Mode Optical Biosensor Performance

NASA Astrophysics Data System (ADS)

Gamba, Jason

Whispering gallery mode (WGM) optical resonator sensors have emerged as promising tools for label-free detection of biomolecules in solution. These devices have even demonstrated single-molecule limits of detection in complex biological uids. This extraordinary sensitivity makes them ideal for low-concentration analytical and diagnostic measurements, but a great deal of work must be done toward understanding and optimizing their performance before they are capable of reliable quantitative measurents. The present work explores the physical processes behind this extreme sensitivity and how to best take advantage of them for practical applications of this technology. I begin by examining the nature of the interaction between the intense electromagnetic elds that build up in the optical biosensor and the biomolecules that bind to its surface. This work addresses the need for a coherent and thorough physical model that can be used to predict sensor behavior for a range of experimental parameters. While this knowledge will prove critical for the development of this technology, it has also shone a light on nonlinear thermo-optical and optical phenomena that these devices are uniquely suited to probing. The surprisingly rapid transient response of toroidal WGM biosensors despite sub-femtomolar analyte concentrations is also addressed. The development of asymmetric boundary layers around these devices under ow is revealed to enhance the capture rate of proteins from solution compared to the spherical sensors used previously. These lessons will guide the design of ow systems to minimize measurement time and consumption of precious sample, a key factor in any medically relevant assay. Finally, experimental results suggesting that WGM biosensors could be used to improve the quantitative detection of small-molecule biomarkers in exhaled breath condensate demonstrate how their exceptional sensitivity and transient response can enable the use of this noninvasive method to probe

WGM Temperature Tracker

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.

2012-01-01

This software implements digital control of a WGM (whispering-gallerymode) resonator temperature based on the dual-mode approach. It comprises one acquisition (dual-channel) and three control modules. The interaction of the proportional-integral loops is designed in the original way, preventing the loops from fighting. The data processing is organized in parallel with the acquisition, which allows the computational overhead time to be suppressed or often completely avoided. WGM resonators potentially provide excellent optical references for metrology, clocks, spectroscopy, and other applications. However, extremely accurate (below micro-Kelvin) temperature stabilization is required. This software allows one specifically advantageous method of such stabilization to be implemented, which is immune to a variety of effects that mask the temperature variation. WGM Temperature Tracker 2.3 (see figure) is a LabVIEW code developed for dual-mode temperature stabilization of WGM resonators. It has allowed for the temperature stabilization at the level of 200 nK with one-second integration time, and 6 nK with 10,000-second integration time, with the above room-temperature set point. This software, in conjunction with the appropriate hardware, can be used as a noncryogenic temperature sensor/ controller with sub-micro-Kelvin sensitivity, which at the time of this reporting considerably outperforms the state of the art.

Optically pumped whispering-gallery mode lasing from 2-μm GaN micro-disks pivoted on Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yiyun; Ma, Zetao; Zhang, Xuhui

2014-06-02

2-μm micro-disks containing InGaN/GaN quantum wells supported on a tiny Si nanotip are fabricated via microsphere lithography followed by dry and wet etch processes. The micro-disks are studied by photoluminescence at both room-temperature and 10 K. Optically pumped blue lasing at room-temperature is observed via whispering-gallery modes (WGMs) with a lasing threshold as low as 8.43 mJ/cm{sup 2}. Optical resonances in the micro-disks are studied through numerical computations and finite-difference time-domain simulations. The WGMs are further confirmed through the measured broadband transmission spectrum, whose transmission minima coincide well with predicted WGM frequencies.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Polarization characteristics of Whispering-Gallery-Mode fiber lasers based on evanescent-wave-coupled gain.

PubMed

Zhang, Yuan-Xian; Pu, Xiao-Yun; Feng, Li; Han, De-Yu; Ren, Yi-Tao

2013-05-20

The polarization characteristics of Whispering-Gallery-Mode (WGM) fiber lasers based on evanescent-wave-coupled gain are investigated. For the laser gain is excited by side-pumping scheme, it is found that the polarization property of lasing emission is simply dependent on the polarized states of the pump beams. The polarization property of lasing emission depends on the propagating situation of the pump beams in an optical fiber if the laser gain is excited by evanescent-wave pumping scheme, that is, if the pump beams within the fiber are meridional beams, the lasing emission is a transverse electric (TE) wave that forms a special radial polarization emission. However, if the pump beams within the fiber are skew beams, both transverse magnetic (TM) and TE waves exist simultaneously in lasing emission that forms a special axially and radially mixed polarization emission. Pumped by skew beams, the wave-number differences between TE and TM waves are also investigated quantitatively, the results demonstrate that the wave-number difference decreases with the increase of the fiber diameter and the refractive index (RI) of the cladding solution. The observed polarization characteristics have been well explained based on lasing radiation mechanism of WGM fiber laser of gain coupled by evanescent wave.

Lithium Niobate Whispering Gallery Resonators: Applications and Fundamental Studies

NASA Astrophysics Data System (ADS)

Maleki, L.; Matsko, A. B.

Optical whispering gallery modes (WGMs) are closed circulating electromagnetic waves undergoing total internal reflection inside an axio-symmetric body of a transparent dielectric that forms a resonator. Radiative losses are negligible in these modes if the radius of the resonator exceeds several tens of wavelengths, and surface scattering losses can be made small with surface conditioning techniques. Thus, the quality factor (Q) in crystalline WGM resonators is limited by material losses that are, nevertheless, extremely small in optical materials. WGM resonators made of LiNbO3 have been successfully used in optics and microwave photonics. The resonators are characterized by narrow bandwidth, in the hundred kilohertz to gigahertz range. A proper choice of highly transparent and/or nonlinear resonator material, like lithium niobate, allows for realization of a number of high performance devices: tunable and multi-pole filters, resonant electro-optic modulators, photonic microwave receivers, opto-electronic microwave oscillators, and parametric frequency converters, among others.

Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter

NASA Technical Reports Server (NTRS)

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

2004-01-01

An experimental tunable, narrow-band-pass electro-optical filter is based on a whispering-gallery resonator. This device is a prototype of tunable filters needed for the further development of reconfigurable networking wavelength-division multiplexers and communication systems that utilize radio-frequency (more specifically, microwave) subcarrier signals on optical carrier signals. The characteristics of whispering-gallery resonators that make them attractive for such applications include high tuning speed, compactness, wide tuning range, low power consumption, and compatibility with single-mode optical fibers. In addition, relative to Fabry-Perot resonators, these devices offer advantages of greater robustness and lower cost. As described in several prior NASA Tech Briefs articles, a whispering-gallery resonator is a spheroidal, disk-like, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. The experimental whispering-gallery tunable filter (see figure) is made from a disk of Z-cut LiNbO3 of 4.8-mm diameter and 0.17-mm thickness. The perimeter of the disk is rounded to a radius of curvature of 100 m. Metal coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery modes by means of a diamond prism. Another diamond prism is used to couple light from the whispering-gallery modes to an output optical fiber. This device is designed and operated to exploit transverse magnetic (TM) whispering- gallery modes, rather than transverse electric (TE) modes because the

Graded-index whispering gallery mode resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor)

2005-01-01

Whispering gallery mode optical resonators which have spatially-graded refractive indices. In one implementation, the refractive index spatially increases with a distance from an exterior surface of such a resonator towards an interior of the resonator to produce substantially equal spectral separations for different whispering gallery modes. An optical coupler may be used with such a resonator to provide proper optical coupling.

Effects of whispering gallery mode in microsphere super-resolution imaging

NASA Astrophysics Data System (ADS)

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.

Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.

PubMed

Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai

2013-07-01

In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.

Low threshold lasing of bubble-containing glass microspheres by non-whispering gallery mode excitation over a wide wavelength range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumagai, Tsutaru, E-mail: kumagai.t.af@m.titech.ac.jp; Kishi, Tetsuo; Yano, Tetsuji

2015-03-21

Bubble-containing Nd{sup 3+}-doped tellurite glass microspheres were fabricated by localized laser heating technique to investigate their optical properties for use as microresonators. Fluorescence and excitation spectra measurements were performed by pumping with a tunable CW-Ti:Sapphire laser. The excitation spectra manifested several sharp peaks due to the conventional whispering gallery mode (WGM) when the pumping laser was irradiated to the edge part of the microsphere. However, when the excitation light was irradiated on the bubble position inside the microsphere, “non-WGM excitation” was induced, giving rise to numerous peaks at a broad wavelength range in the excitation spectra. Thus, efficient excitation wasmore » achieved over a wide wavelength range. Lasing threshold excited at the bubble position was much lower than that for the excitation at the edges of the microsphere. The lowest value of the laser threshold was 34 μW for a 4 μm sphere containing a 0.5 μm bubble. Efficiency of the excitation at the bubble position with broadband light was calculated to be 5 times higher than that for the edge of the microsphere. The bubble-containing microsphere enables efficient utilization of broadband light excitation from light-emitting diodes and solar light.« less

Whispering gallery modes in a spherical microcavity with a photoluminescent shell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grudinkin, S. A., E-mail: grudink@gvg.ioffe.ru; Dontsov, A. A.; Feoktistov, N. A.

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.

Whispering-gallery nanocavity plasmon-enhanced Raman spectroscopy

PubMed Central

Zhang, Jing; Li, Jinxing; Tang, Shiwei; Fang, Yangfu; Wang, Jiao; Huang, Gaoshan; Liu, Ran; Zheng, Lirong; Cui, Xugao; Mei, Yongfeng

2015-01-01

The synergy effect in nature could enable fantastic improvement of functional properties and associated effects. The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors. Here, greatly-enhanced SERS detection is realized based on rolled-up tubular nano-resonators decorated with silver nanoparticles. The synergy effect between whispering-gallery-mode (WGM) and surface plasmon leads to an extra enhancement at the order of 105 compared to non-resonant flat SERS substrates, which can be well tuned by altering the diameter of micron- and nanotubes and the excitation laser wavelengths. Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials. PMID:26443526

Comparison of various excitation and detection schemes for dye-doped polymeric whispering gallery mode micro-lasers.

PubMed

Siegle, Tobias; Kellerer, Jonas; Bonenberger, Marielle; Krämmer, Sarah; Klusmann, Carolin; Müller, Marius; Kalt, Heinz

2018-02-05

We compare different excitation and collection configurations based on free-space optics and evanescently coupled tapered fibers for both lasing and fluorescence emission from dye-doped doped polymeric whispering gallery mode (WGM) micro-disk lasers. The focus of the comparison is on the lasing threshold and efficiency of light collection. With the aid of optical fibers, we localize the pump energy to the cavity-mode volume and reduce the necessary pump energy to achieve lasing by two orders of magnitude. When using fibers for detection, the collection efficiency is enhanced by four orders of magnitude compared to a free-space read-out perpendicular to the resonator plane. By enhancing the collection efficiency we are able to record a pronounced modulation of the dye fluorescence under continuous wave (cw) pumping conditions evoked by coupling to the WGMs. Alternatively to fibers as a collection tool, we present a read-out technique based on the detection of in-plane radiated light. We show that this method is especially beneficial in an aqueous environment as well as for size-reduced micro-lasers where radiation is strongly pronounced. Furthermore, we show that this technique allows for the assignment of transverse electric (TE) and transverse magnetic (TM) polarization to the observed fundamental modes in a water environment by performing polarization-dependent photoluminescence (PL) spectroscopy. We emphasize the importance of the polarization determination for sensing applications and verify expected differences in the bulk refractive index sensitivity for TE and TM WGMs experimentally.

Multiwavelength optical source at 12.5-GHz optical spacing based on a coupled optoelectronic oscillator with a whispering gallery mode resonator

NASA Astrophysics Data System (ADS)

Kossakovski, Dmitri; Solomatine, Iouri V.; Morozov, Nikolai; Ilchenko, Vladimir S.

2004-06-01

The evolution of optical networks calls for denser channel grids and increased number of channels. Additionally, there is a system architecture benefit to eliminate the banks of DFB lasers that act as light sources for individual channels, and use instead a single multi-wavelength source. We have demonstrated a compact multi-wavelength optical source (MWS) for 12.5 GHz DWDM. At least 16 channels are observed within 3 dB optical power bandwidth with optical spectrum contrast ratio exceeding 28 dB. The source is based on a coupled opto-electronic oscillator (COEO) with an optical whispering gallery mode (WGM) microresonator. Free spectral range of the resonator determines the spacing of the optical channels in the MWS. The spacing can be scaled up or down depending on design requirements. The resonator is robustly packaged and fiber pigtailed. In the RF domain the MWS acts as oscillator with operational frequency of 12.5 GHz.

Chiral modes and directional lasing at exceptional points

PubMed Central

Peng, Bo; Özdemir, Şahin Kaya; Liertzer, Matthias; Chen, Weijian; Kramer, Johannes; Yılmaz, Huzeyfe; Wiersig, Jan; Yang, Lan

2016-01-01

Controlling the emission and the flow of light in micro- and nanostructures is crucial for on-chip information processing. Here we show how to impose a strong chirality and a switchable direction of light propagation in an optical system by steering it to an exceptional point (EP)—a degeneracy universally occurring in all open physical systems when two eigenvalues and the corresponding eigenstates coalesce. In our experiments with a fiber-coupled whispering-gallery-mode (WGM) resonator, we dynamically control the chirality of resonator modes and the emission direction of a WGM microlaser in the vicinity of an EP: Away from the EPs, the resonator modes are nonchiral and laser emission is bidirectional. As the system approaches an EP, the modes become chiral and allow unidirectional emission such that by transiting from one EP to another one the direction of emission can be completely reversed. Our results exemplify a very counterintuitive feature of non-Hermitian physics that paves the way to chiral photonics on a chip. PMID:27274059

Electro-pumped whispering gallery mode ZnO microlaser array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, G. Y.; State Key Laboratory of Bioelectronics, School of Electronic Science and Engineering, Southeast University, Nanjing 210096; Li, J. T.

2015-01-12

By employing vapor-phase transport method, ZnO microrods are fabricated and directly assembled on p-GaN substrate to form a heterostructural microlaser array, which avoids of the relatively complicated etching process comparing previous work. Under applied forward bias, whispering gallery mode ZnO ultraviolet lasing is obtained from the as-fabricated heterostructural microlaser array. The device's electroluminescence originates from three distinct electron-hole recombination processes in the heterojunction interface, and whispering gallery mode ultraviolet lasing is obtained when the applied voltage is beyond the lasing threshold. This work may present a significant step towards future fabrication of a facile technique for micro/nanolasers.

Critical Coupling Between Optical Fibers and WGM Resonators

NASA Technical Reports Server (NTRS)

Matsko, Andrey; Maleki, Lute; Itchenko, Vladimir; Savchenkov, Anatoliy

2009-01-01

Two recipes for ensuring critical coupling between a single-mode optical fiber and a whispering-gallery-mode (WGM) optical resonator have been devised. The recipes provide for phase matching and aperture matching, both of which are necessary for efficient coupling. There is also a provision for suppressing intermodal coupling, which is detrimental because it drains energy from desired modes into undesired ones. According to one recipe, the tip of the single-mode optical fiber is either tapered in diameter or tapered in effective diameter by virtue of being cleaved at an oblique angle. The effective index of refraction and the phase velocity at a given position along the taper depend on the diameter (or effective diameter) and the index of refraction of the bulk fiber material. As the diameter (or effective diameter) decreases with decreasing distance from the tip, the effective index of refraction also decreases. Critical coupling and phase matching can be achieved by placing the optical fiber and the resonator in contact at the proper point along the taper. This recipe is subject to the limitation that the attainable effective index of refraction lies between the indices of refraction of the bulk fiber material and the atmosphere or vacuum to which the resonator and fiber are exposed. The other recipe involves a refinement of the previously developed technique of prism coupling, in which the light beam from the optical fiber is collimated and focused onto one surface of a prism that has an index of refraction greater than that of the resonator. Another surface of the prism is placed in contact with the resonator. The various components are arranged so that the collimated beam is focused at the prism/resonator contact spot. The recipe includes the following additional provisions:

Microwave Oscillators Based on Nonlinear WGM Resonators

NASA Technical Reports Server (NTRS)

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

2006-01-01

Optical oscillators that exploit resonantly enhanced four-wave mixing in nonlinear whispering-gallery-mode (WGM) resonators are under investigation for potential utility as low-power, ultra-miniature sources of stable, spectrally pure microwave signals. There are numerous potential uses for such oscillators in radar systems, communication systems, and scientific instrumentation. The resonator in an oscillator of this type is made of a crystalline material that exhibits cubic Kerr nonlinearity, which supports the four-photon parametric process also known as four-wave mixing. The oscillator can be characterized as all-optical in the sense that the entire process of generation of the microwave signal takes place within the WGM resonator. The resonantly enhanced four-wave mixing yields coherent, phase-modulated optical signals at frequencies governed by the resonator structure. The frequency of the phase-modulation signal, which is in the microwave range, equals the difference between the frequencies of the optical signals; hence, this frequency is also governed by the resonator structure. Hence, further, the microwave signal is stable and can be used as a reference signal. The figure schematically depicts the apparatus used in a proof-of-principle experiment. Linearly polarized pump light was generated by an yttrium aluminum garnet laser at a wavelength of 1.32 microns. By use of a 90:10 fiber-optic splitter and optical fibers, some of the laser light was sent into a delay line and some was transmitted to one face of glass coupling prism, that, in turn, coupled the laser light into a crystalline CaF2 WGM disk resonator that had a resonance quality factor (Q) of 6x10(exp 9). The output light of the resonator was collected via another face of the coupling prism and a single-mode optical fiber, which transmitted the light to a 50:50 fiber-optic splitter. One output of this splitter was sent to a slow photodiode to obtain a DC signal for locking the laser to a particular

Interrelation of the effects caused by the rotation of the whispering gallery modes resonator

NASA Astrophysics Data System (ADS)

Dmitriyeva, Anna D.; Filatov, Yuri V.; Shalymov, Egor V.; Venediktov, Vladimir Yu.

2016-11-01

Optical whispering gallery modes resonators are characterized by unique properties: ultrahigh quality factor, small amount of the modes and small size. It allows to use them in compact high-precision measuring devices. In particular these resonators can be used in the composition of gyros. For today all researches, devoted to the application of the whispering gallery modes resonators in gyros, deals only with one of induced by the rotation effects (Sagnac effect or the influence of centrifugal forces on the resonator size). In this work we study the interrelation of the effects caused by the rotation of the whispering gallery modes resonator. Also in work we consider the possibility of joint application of both effects (the influence of centrifugal forces and Sagnac effect) for measuring angular velocity.

Three-dimensional whispering gallery modes in InGaAs nanoneedle lasers on silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tran, T.-T. D.; Chen, R.; Ng, K. W.

2014-09-15

As-grown InGaAs nanoneedle lasers, synthesized at complementary metal–oxide–semiconductor compatible temperatures on polycrystalline and crystalline silicon substrates, were studied in photoluminescence experiments. Radiation patterns of three-dimensional whispering gallery modes were observed upon optically pumping the needles above the lasing threshold. Using the radiation patterns as well as finite-difference-time-domain simulations and polarization measurements, all modal numbers of the three-dimensional whispering gallery modes could be identified.

Laser-tuned whispering gallery modes in a solid-core microstructured optical fibre integrated with magnetic fluids

PubMed Central

Lin, Wei; Zhang, Hao; Liu, Bo; Song, Binbin; Li, Yuetao; Yang, Chengkun; Liu, Yange

2015-01-01

A laser-assisted tuning method of whispering gallery modes (WGMs) in a cylindrical microresonator based on magnetic-fluids-infiltrated microstructured optical fibres (MFIMOFs, where MF and MOF respectively refer to magnetic fluid and microstructured optical fibre) is proposed, experimentally demonstrated and theoretically analysed in detail. The MFIMOF is prepared by infiltrating the air-hole array of the MOF using capillary action effect. A fibre-coupling system is set up for the proposed MFIMOF-based microresonator to acquire an extinction ratio up to 25 dB and a Q-factor as large as 4.0 × 104. For the MF-infiltrated MOF, the light propagating in the fibre core region would rapidly spread out and would be absorbed by the MF-rod array cladding to induce significant thermal effect. This has been exploited to achieve a WGM resonance wavelength sensitivity of 0.034 nm/mW, which is ~20 times higher than it counterpart without MF infiltration. The wavelength response of the resonance dips exhibit linear power dependence, and owing to such desirable merits as ease of fabrication, high sensitivity and laser-assisted tunability, the proposed optical tuning approach of WGMs in the MFIMOF would find promising applications in the areas of optical filtering, sensing, and signal processing, as well as future all-optical networking systems. PMID:26632445

GaN microwires as optical microcavities: whispering gallery modes Vs Fabry-Perot modes.

PubMed

Coulon, Pierre-Marie; Hugues, Maxime; Alloing, Blandine; Beraudo, Emmanuel; Leroux, Mathieu; Zuniga-Perez, Jesus

2012-08-13

GaN microwires grown by metalorganic vapour phase epitaxy and with radii typically on the order of 1-5 micrometers exhibit a number of resonances in their photoluminescence spectra. These resonances include whispering gallery modes and transverse Fabry-Perot modes. A detailed spectroscopic study by polarization-resolved microphotoluminescence, in combination with electron microscopy images, has enabled to differentiate both kinds of modes and determined their main spectral properties. Finally, the dispersion of the ordinary and extraordinary refractive indices of strain-free GaN in the visible-UV range has been obtained thanks to the numerical simulation of the observed modes.

Improving the Optical Quality Factor of the WGM Resonator

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Matsko, Andrey; Iltchenko, Vladimir

2008-01-01

Resonators usually are characterized with two partially dependent values: finesse (F) and quality factor (Q). The finesse of an empty Fabry-Perot (FP) resonator is defined solely by the quality of its mirrors and is calculated as F=piR(exp 1/2)/(1-R). The maximum up-to-date value of reflectivity R approximately equal to 1 - 1.6 x 10(exp -6) is achieved with dielectric mirrors. An FP resonator made with the mirrors has finesse F=1.9 x 10(exp 6). Further practical increase of the finesse of FP resonators is problematic because of the absorption and the scattering of light in the mirror material through fundamental limit on the reflection losses given by the internal material losses and by thermodynamic density fluctuations on the order of parts in 109. The quality factor of a resonator depends on both its finesse and its geometrical size. A one-dimensional FP resonator has Q=2 F L/lambda, where L is the distance between the mirrors and lambda is the wavelength. It is easy to see that the quality factor of the resonator is unlimited because L is unlimited. F and Q are equally important. In some cases, finesse is technically more valuable than the quality factor. For instance, buildup of the optical power inside the resonator, as well as the Purcell factor, is proportional to finesse. Sometimes, however, the quality factor is more valuable. For example, inverse threshold power of intracavity hyperparametric oscillation is proportional to Q(exp 2) and efficiency of parametric frequency mixing is proportional to Q(exp 3). Therefore, it is important to know both the maximally achievable finesse and quality factor values of a resonator. Whispering gallery mode (WGM) resonators are capable of achieving larger finesse compared to FP resonators. For instance, fused silica resonators with finesse 2.3 x 10(exp 6) and 2.8 x 10(exp 6) have been demonstrated. Crystalline WGM resonators reveal even larger finesse values, F=6.3 x 10(exp 6), because of low attenuation of light in the

The comparison of the influence of centrifugal forces and the Sagnac effect on a rotating whispering gallery modes resonators

NASA Astrophysics Data System (ADS)

Filatov, Yuri V.; Shalymov, Egor V.; Venediktov, Vladimir Yu.; Dmitrieva, Anna D.

2016-10-01

The parameters of whispering gallery modes resonators can be significantly modified under the action of external factors, for instance, in the case of resonator movement. The effects, which take place in the moving resonators of whispering gallery modes, can be employed for measuring of the angular velocity. In this work we was compared the influence of centrifugal forces and the Sagnac effect on the eigenfrequencies (wavelengths) of whispering gallery modes resonators. Also work is devoted mutual relationships of the effects.

Active chiral control of GHz acoustic whispering-gallery modes

NASA Astrophysics Data System (ADS)

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.

Super low threshold plasmonic WGM lasing from an individual ZnO hexagonal microrod on an Au substrate for plasmon lasers.

PubMed

Dong, H M; Yang, Y H; Yang, G W

2015-03-05

We demonstrate an individual ZnO hexagonal microrod on the surface of an Au substrate which can become new sources for manufacturing miniature ZnO plasmon lasers by surface plasmon polariton coupling to whispering-gallery modes (WGMs). We also demonstrate that the rough surface of Au substrates can acquire a more satisfied enhancement of ZnO emission if the surface geometry of Au substrates is appropriate. Furthermore, we achieve high Q factor and super low threshold plasmonic WGM lasing from an individual ZnO hexagonal microrod on the surface of the Au substrate, in which Q factor can reach 5790 and threshold is 0.45 KW/cm(2) which is the lowest value reported to date for ZnO nanostructures lasing, at least 10 times smaller than that of ZnO at the nanometer. Electron transfer mechanisms are proposed to understand the physical origin of quenching and enhancement of ZnO emission on the surface of Au substrates. These investigations show that this novel coupling mode holds a great potential of ZnO hexagonal micro- and nanorods for data storage, bio-sensing, optical communications as well as all-optic integrated circuits.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goryachev, Maxim; Farr, Warrick G.; Carmo Carvalho, Natalia do

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 muchmore » 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.« less

Demonstration of versatile whispering-gallery micro-lasers for remote refractive index sensing.

PubMed

Wan, Lei; Chandrahalim, Hengky; Zhou, Jian; Li, Zhaohui; Chen, Cong; Cho, Sangha; Zhang, Hui; Mei, Ting; Tian, Huiping; Oki, Yuji; Nishimura, Naoya; Fan, Xudong; Guo, L Jay

2018-03-05

We developed chip-scale remote refractive index sensors based on Rhodamine 6G (R6G)-doped polymer micro-ring lasers. The chemical, temperature, and mechanical sturdiness of the fused-silica host guaranteed a flexible deployment of dye-doped polymers for refractive index sensing. The introduction of the dye as gain medium demonstrated the feasibility of remote sensing based on the free-space optics measurement setup. Compared to the R6G-doped TZ-001, the lasing behavior of R6G-doped SU-8 polymer micro-ring laser under an aqueous environment had a narrower spectrum linewidth, producing the minimum detectable refractive index change of 4 × 10 -4 RIU. The maximum bulk refractive index sensitivity (BRIS) of 75 nm/RIU was obtained for SU-8 laser-based refractive index sensors. The economical, rapid, and simple realization of polymeric micro-scale whispering-gallery-mode (WGM) laser-based refractive index sensors will further expand pathways of static and dynamic remote environmental, chemical, biological, and bio-chemical sensing.

All-optical Photonic Oscillator with High-Q Whispering Gallery Mode Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy A.; Matsko, Andrey B.; Strekalov, Dmitry; Mohageg, Makan; Iltchenko, Vladimir S.; Maleki, Lute

2004-01-01

We demonstrated low threshold optical photonic hyper-parametric oscillator in a high-Q 10(exp 10) CaF2 whispering gallery mode resonator which generates stable 8.5 GHz signal. The oscillations result from the resonantly enhanced four wave mixing occurring due to Kerr nonlinearity of the material.

Second-harmonic generation using tailored whispering gallery modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumeige, Yannick; Feron, Patrice

It has been shown that whispering gallery modes can be used to obtain a combination of modal and geometrical quasi-phase-matching in second-harmonic generation. This could be achieved in isotropic, nonferroelectric, strongly dispersive and highly nonlinear materials such as III-V semiconductors. Unfortunately the poor overlap between the second-harmonic field and second order nonlinear polarization limits the conversion efficiency. In this paper we show that by engineering the refractive index it is possible to increase field overlap and to enhance effective second order nonlinear polarization of semiconductor microdisks.

Method of fabricating a whispering gallery mode resonator

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy A. (Inventor); Matkso, Andrey B. (Inventor); Iltchenko, Vladimir S. (Inventor); Maleki, Lute (Inventor)

2011-01-01

A method of fabricating a whispering gallery mode resonator (WGMR) is provided. The WGMR can be fabricated from a particular material, annealed, and then polished. The WGMR can be repeatedly annealed and then polished. The repeated polishing of the WGMR can be carried out using an abrasive slurry. The abrasive slurry can have a predetermined, constant grain size. Each subsequent polishing of the WGMR can use an abrasive slurry having a grain size that is smaller than the grain size of the abrasive slurry of the previous polishing iteration.

Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

DOEpatents

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.

Integration of Microsphere Resonators with Bioassay Fluidics for Whispering Gallery Mode Imaging

PubMed Central

Kim, Daniel C.; Armendariz, Kevin P.

2013-01-01

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. PMID:23615457

Highly sensitive mode mapping of whispering-gallery modes by scanning thermocouple-probe microscopy.

PubMed

Klein, Angela E; Schmidt, Carsten; Liebsch, Mattes; Janunts, Norik; Dobynde, Mikhail; Tünnermann, Andreas; Pertsch, Thomas

2014-03-01

We propose a method for mapping optical near-fields with the help of a thermocouple scanning-probe microscope tip. As the tip scans the sample surface, its apex is heated by light absorption, generating a thermovoltage. The thermovoltage map represents the intensity distribution of light at the sample surface. The measurement technique has been employed to map optical whispering-gallery modes in fused silica microdisk resonators operating at near-infrared wavelengths. The method could potentially be employed for near-field imaging of a variety of systems in the near-infrared and visible spectral range.

Spinning optical resonator sensor for torsional vibrational applications measurements

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Gatherer, Andrew; Ibrahim, Mariam S.

2016-03-01

Spinning spherical resonators in the torsional vibrational applications could cause a shift in its whispering gallery mode (WGM). The centripetal force acting on the spinning micro sphere resonator will leads to these WGM shifts. An analysis and experiment were carried out in this paper to investigate and demonstrate this effect using different polymeric resonators. In this experiment, centripetal force exerted by the DC-Motor on the sphere induces an elastic deformation of the resonator. This in turn induces a shift in the whispering gallery modes of the sphere resonator. Materials used for the sphere are polydimethylsiloxane (PDMS 60:1 where 60 parts base silicon elastomer to 1 part polymer curing agent by volume) with shear modulus (G≍1kPa), (PDMS 10:1) with shear modulus (G≍300kPa), polymethylmethacrylate (PMMA, G≍2.6×109GPa) and silica (G≍3×1010 GPa). The sphere size was kept constant with 1mm in diameter for all above materials. The optical modes of the sphere exit using a tapered single mode optical fiber that is coupled to a distributed feedback laser. The transmission spectrum through the fiber is monitored to detect WGM shifts. The results showed the resonators with smaller shear modulus G experience larger WGM shift due to the larger mechanical deformation induced by the applied external centripetal force. Also, the results show that angular velocity sensors used in the torsional vibrational applications could be designed using this principle.

Direct electrical-to-optical conversion and light modulation in micro whispering-gallery-mode resonators

NASA Technical Reports Server (NTRS)

Maleki, Lute (Inventor); Levi, Anthony F. J. (Inventor)

2005-01-01

Techniques for directly converting an electrical signal into an optical signal by using a whispering gallery mode optical resonator formed of a dielectric material that allows for direct modulation of optical absorption by the electrical signal.

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

PubMed

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.

Modelling of rotation-induced frequency shifts in whispering gallery modes

NASA Astrophysics Data System (ADS)

Venediktov, V. Yu; Kukaev, A. S.; Filatov, Yu V.; Shalymov, E. V.

2018-02-01

We study the angular velocity sensors based on whispering gallery mode resonators. Rotation of such resonators gives rise to various effects that can cause a spectral shift of their modes. Optical methods allow this shift to be determined with high precision, which can be used practically to measure the angular velocity in inertial orientation and navigation systems. The basic principles of constructing the angular velocity sensors utilising these effects are considered, their advantages and drawbacks are indicated. We also study the interrelation between the effects and the possibility of their mutual influence on each other. Based on the analytical studies of the effects, we consider the possibility of their combined application for angular velocity measurements.

Whispering-Gallery Mode Resonators for Detecting Cancer

PubMed Central

Pongruengkiat, Weeratouch; Pechprasarn, Suejit

2017-01-01

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. PMID:28902169

Reconfigurable Liquid Whispering Gallery Mode Microlasers

PubMed Central

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

2016-01-01

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. PMID:27256771

Tailoring of the free spectral range and geometrical cavity dispersion of a microsphere by a coating layer.

PubMed

Ristić, Davor; Mazzola, Maurizio; Chiappini, Andrea; Rasoloniaina, Alphonse; Féron, Patrice; Ramponi, Roberta; Righini, Giancarlo C; Cibiel, Gilles; Ivanda, Mile; Ferrari, Maurizio

2014-09-01

The modal dispersion of a whispering gallery mode (WGM) resonator is a very important parameter for use in all nonlinear optics applications. In order to tailor the WGM modal dispersion of a microsphere, we have coated a silica microsphere with a high-refractive-index coating in order to study its effect on the WGM modal dispersion. We used Er(3+) ions as a probe for a modal dispersion assessment. We found that, by varying the coating thickness, the geometrical cavity dispersion can be used to shift overall modal dispersion in a very wide range in both the normal and anomalous dispersion regime.

Dynamic Fano-like resonances in erbium-doped whispering-gallery-mode microresonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Fuchuan; Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130; Peng, Bo

2014-09-08

We report Fano-like asymmetric resonances modulated by optical gain in a whispering-gallery-mode resonator fabricated from erbium-doped silica. A time-dependent gain profile leads to dynamically varying sharp asymmetric resonances with features similar to Fano resonances. Depending on the scan speed of the frequency of the probe laser and the pump-probe power ratio, transmission spectra of the active microcavity exhibit a resonance dip, a resonance peak, or a Fano-like resonance.

All-polymer whispering gallery mode sensor system.

PubMed

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.

Tunable liquid-crystal microshell-laser based on whispering-gallery modes and photonic band-gap mode lasing.

PubMed

Lu, Yuelan; Yang, Yue; Wang, Yan; Wang, Lei; Ma, Ji; Zhang, Lingli; Sun, Weimin; Liu, Yongjun

2018-02-05

The lasing behaviors of dye-doped cholesteric liquid crystal (DDCLC) microshells fabricated with silica-glass-microsphere coated DDCLCs were examined. Lasing characteristics were studied in a carrier medium with different refractive indices. The lasing in spherical cholesteric liquid crystals (CLCs) was attributed to two mechanisms, photonic band-gap (PBG) lasing and whispering-gallery modes (WGMs), which can independently exist by varying the chiral agent concentration and pumping energy. It was also found that DDCLC microshells can function as highly sensitive thermal sensors, with a temperature sensitivity of 0.982 nm °C -1 in PBG modes and 0.156 nm °C -1 in WGMs.

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

PubMed Central

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

Microwave photonics systems based on whispering-gallery-mode resonators.

PubMed

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

2013-08-05

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.

Light scattering by magnons in whispering gallery mode cavities

NASA Astrophysics Data System (ADS)

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.

Ultra-high Q terahertz whispering-gallery modes in a silicon resonator

NASA Astrophysics Data System (ADS)

Vogt, Dominik Walter; Leonhardt, Rainer

2018-05-01

We report on the first experimental demonstration of terahertz (THz) whispering-gallery modes (WGMs) with an ultra-high quality factor of 1.5 × 104 at 0.62 THz. The WGMs are observed in a high resistivity float zone silicon spherical resonator coupled to a sub-wavelength silica waveguide. A detailed analysis of the coherent continuous wave THz spectroscopy measurements combined with a numerical model based on Mie-Debye-Aden-Kerker theory allows us to unambiguously identify the observed higher order radial THz WGMs.

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

PubMed Central

Su, Judith

2017-01-01

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. PMID:28282881

Physical Investigations of Small Particles: (I) Aerosol Particle Charging and Flux Enhancement and (II) Whispering Gallery Mode Sensing

NASA Astrophysics Data System (ADS)

Lopez-Yglesias, Xerxes

of the molecule and the electromagnetic interaction between the molecule and particle, especially for the neutral particle case, are completely ignored, or, as is often the case for a permanent dipole vapor species, strongly underestimated. Comparing our model to these classical models we determine an "enhancement factor" to characterize how important the addition of these physical parameters and processes is to the understanding of particle nucleation and growth. Part II: Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and non-specific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, lambdaR, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.

Single-longitudinal-mode, narrow bandwidth double-ring fiber laser stabilized by an efficiently taper-coupled high roundness microsphere resonator

NASA Astrophysics Data System (ADS)

Wan, Hongdan; Liu, Linqian; Ding, Zuoqin; Wang, Jie; Xiao, Yu; Zhang, Zuxing

2018-06-01

This paper proposes and demonstrates a single-longitudinal-mode, narrow bandwidth fiber laser, using an ultra-high roundness microsphere resonator (MSR) with a stabilized package as the single-longitudinal-mode selector inside a double-ring fiber cavity. By improving the heating technology and surface cleaning process, MSR with high Q factor are obtained. With the optimized coupling condition, light polarization state and fiber taper diameter, we achieve whispering gallery mode (WGM) spectra with a high extinction ratio of 23 dB, coupling efficiency of 99.5%, a 3 dB bandwidth of 1 pm and a side-mode-suppression-ratio of 14.5 dB. The proposed fiber laser produces single-longitudinal-mode laser output with a 20-dB frequency linewidth of about 340 kHz, a signal-to-background ratio of 54 dB and a high long-term stability without mode-hopping, which is potential for optical communication and sensing applications.

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

DOEpatents

Stallard, B.W.; Makowski, M.A.; Byers, J.A.

1992-05-19

An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam is described. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k[sub [phi

Whispering gallery resonators for optical sensing

NASA Astrophysics Data System (ADS)

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.

Simplified Generation of High-Angular-Momentum Light Beams

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Strekalov, Dmitry; Grudinin, Ivan

2007-01-01

A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering- gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. ( Bessel beam denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.) High-angular-momentum light beams are used in some applications in biology and nanotechnology, wherein they are known for their ability to apply torque to make microscopic objects rotate. High-angular-momentum light beams could also be used to increase bandwidths of fiber-optic communication systems. The present simplified method of generating a high-angular-momentum light beam was conceived as an alternative to prior such methods, which are complicated and require optical setups that include, variously, holograms, modulating Fabry-Perot cavities, or special microstructures. The present simplified method exploits a combination of the complex structure of the electromagnetic field inside a WGM resonator, total internal reflection in the WGM resonator, and the electromagnetic modes supported by an optical fiber. The optical fiber used to extract light from the WGM resonator is made of fused quartz. The output end of this fiber is polished flat and perpendicular to the fiber axis. The input end of this fiber is cut on a slant and placed very close to the WGM resonator at an appropriate position and orientation. To excite the resonant whispering- gallery modes, light is introduced into the WGM resonator via another optical fiber that is part of a pigtailed fiber-optic coupler. Light extracted from the WGM resonator is transformed into a high-angular- momentum beam inside the extraction optical fiber and this beam is emitted from the

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neilson, Jeffrey M.

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 modemore » converting reflector is substantially circular.« less

High-Q enhancement of attractive and repulsive optical forces between coupled whispering-gallery- mode resonators.

PubMed

Povinelli, Michelle; Johnson, Steven; Lonèar, Marko; Ibanescu, Mihai; Smythe, Elizabeth; Capasso, Federico; Joannopoulos, J

2005-10-03

We have calculated the optically-induced force between coupled high-Q whispering gallery modes of microsphere resonators. Attractive and repulsive forces are found, depending whether the bi-sphere mode is symmetric or antisymmetric. The magnitude of the force is linearly proportional to the total power in the spheres and consequently linearly enhanced by Q. Forces on the order of 100 nN are found for Q=108, large enough to cause displacements in the range of 1mum when the sphere is attached to a fiber stem with spring constant 0.004 N/m.

A Solid State Ultraviolet Lasers Based on Cerium-Doped LiCaAIF(sub 6) Crystal Resonator

NASA Technical Reports Server (NTRS)

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.

Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Guoping, E-mail: guoping.lin@femto-st.fr; Diallo, Souleymane; Saleh, Khaldoun

2014-12-08

We report the observation of stimulated Brillouin scattering and lasing at 1550 nm in barium fluoride (BaF{sub 2}) crystal. Brillouin lasing was achieved with ultra-high quality (Q) factor monolithic whispering gallery mode 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{sub 2} resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

Resonant Optical Circuits Based on Coupling Between Whispering Gallery Modes in Dielectric Microresonators

DTIC Science & Technology

2007-12-30

111111 (2006). 2. S.P. Ashili , V.N. Astratov, and E.C.H. Sykes, “The effects of inter-cavity separation on optical coupling in dielectric bispheres...chains of coupled spherical cavities,” Opt. Lett. 32, 409-411 (2007). 4. V.N. Astratov, and S.P. Ashili , “Percolation of light through whispering...Propagation via Whispering Gallery Modes in 3-D Networks of Coupled Spherical Cavities (Talk), V.N. Astratov, S.P. Ashili , and A.M. Kapitonov, in Frontiers in

Whispering Gallery Optical Resonator Spectroscopic Probe and Method

NASA Technical Reports Server (NTRS)

Anderson, Mark S. (Inventor)

2014-01-01

Disclosed herein is a spectroscopic probe comprising at least one whispering gallery mode optical resonator disposed on a support, the whispering gallery mode optical resonator comprising a continuous outer surface having a cross section comprising a first diameter and a second diameter, wherein the first diameter is greater than the second diameter. A method of measuring a Raman spectrum and an Infra-red spectrum of an analyte using the spectroscopic probe is also disclosed.

Classification of antibiotics by neural network analysis of optical resonance data of whispering gallery modes in dielectric microspheres

NASA Astrophysics Data System (ADS)

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

2012-04-01

A novel emerging technique for the label-free analysis of nanoparticles and biomolecules in liquid fluids using optical micro cavity resonance of whispering-gallery-type modes is being developed.A scheme based on polymer microspheres fixed by adhesive on the evanescence wave coupling element has been used. We demonstrated that the only spectral shift can't be used for identification of biological agents by developed approach. So neural network classifier for biological agents and micro/nano particles classification has been developed. The developed technique is the following. While tuning the laser wavelength images were recorded as avi-file. All sequences were broken into single frames and the location of the resonance was allocated in each frame. The image was filtered for noise reduction and integrated over two coordinates for evaluation of integrated energy of a measured signal. As input data normalized resonance shift of whispering-gallery modes and the relative efficiency of whispering-gallery modes excitation were used. Other parameters such as polarization of excited light, "center of gravity" of a resonance spectra etc. are also tested as input data for probabilistic neural network. After network designing and training we estimated the accuracy of classification. The classification of antibiotics such as penicillin and cephasolin have been performed with the accuracy of not less 97 %. Developed techniques can be used for lab-on-chip sensor based diagnostic tools as for identification of different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells and for dynamics of a delivery of medicines to bodies.

Hyperparametric effects in a whispering-gallery mode rutile dielectric resonator at liquid helium temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nand, Nitin R.; Goryachev, Maxim; Floch, Jean-Michel le

2014-10-07

We report the first observation of low power drive level sensitivity, hyperparametric amplification, and single-mode hyperparametric oscillations in a dielectric rutile whispering-gallery mode resonator at 4.2 K. The latter gives rise to a comb of sidebands at 19.756 GHz. Whereas, most frequency combs in the literature have been observed in optical systems using an ensemble of equally spaced modes in microresonators or fibers, the present work represents generation of a frequency comb using only a single-mode. The experimental observations are explained by an additional 1/2 degree-of-freedom originating from an intrinsic material nonlinearity at optical frequencies, which affects the microwave propertiesmore » due to the extremely low loss of rutile. Using a model based on lumped circuits, we demonstrate that the resonance between the photonic and material 1/2 degree-of-freedom, is responsible for the hyperparametric energy transfer in the system.« less

High-Q whispering-gallery mode sensor in liquids

NASA Astrophysics Data System (ADS)

Nadeau, Jay L.; Ilchenko, Vladimir S.; Kossakovski, Dmitri; Bearman, Gregory H.; Maleki, Lute

2002-06-01

Optical sensing of biomolecules on microfabricated glass surfaces requires surface coatings that minimize nonspecific binding while preserving the optical properties of the sensor. Microspheres with whispering-gallery (WG) modes can achieve quality factor (Q) levels many orders of magnitude greater than those of other WG-based microsensors: greater than 1010 in air, and greater than 109 in a variety of solvents, including methanol, H2O and phosphate buffered saline (PBS). The presence of dyes that absorb in the wavelength of the WG excitation in the evanescent zone can cause this Q value to drop by almost 3 orders of magnitude. Silanization of the surface with mercapto-terminal silanes is compatible with high Q (>109), but chemical cross-linking of streptavidin reduces the Q to 105-106 due to build-up of a thick, irregular layer of protein. However, linkage of biotin to the silane terminus preserves the Q at a ~2x107 and yields a reactive surface sensitive to avidin-containing ligands in a concentration-dependent manner. Improvements in the reliability of the surface chemistry show promise for construction of an ultrasensitive biosensor.

Protein-based flexible whispering gallery mode resonators

NASA Astrophysics Data System (ADS)

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.

Liquid crystal emulsion micro-droplet WGM resonators

NASA Astrophysics Data System (ADS)

Ježek, Jan; Pilát, Zdeněk.; Brzobohatý, Oto; Jonáš, Alexandr; Aas, Mehdi; Kiraz, Alper; Zemánek, Pavel

2014-12-01

We introduce tunable optofluidic microlasers based on optically stretched or thermally modified, dye-doped emulsion droplets of liquid crystals (LC) confined in a dual-beam optical trap. Droplets were created in microfluidic chips or by shaking. Optically trapped microdroplets emulsified in water and stained with fluorescent dye act as an active ultrahigh-Q optical resonant cavity hosting whispering gallery modes (WGMs). Tuning of the laser emission wavelength was achieved by a controlled deformation of the droplet shape using light-induced forces generated by dual-beam optical trap and by thermal changing of the order in the LC.

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

DOEpatents

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.

Real-time detection and analysis of Whispering gallery mode resonance in high-throughput flowing monodisperse microdroplets

NASA Astrophysics Data System (ADS)

El Abed, Abdel I.; Taly, Valérie

2013-11-01

We investigate light coupling into highly monodisperse liquid microdroplets, which are produced and manipulated at kHz rates in a microfluidic device. We show that such coupling leads to Whispering gallery mode resonances (WGMs) which are detected and analyzed versus time during the fast displacement of microdroplets into the microfluidic channel. Our results show that droplet-based microfluidics may be applied advantageously in the promising field of high-throughput label-free biosensing.

Exploring the Frequency Stability Limits of Whispering Gallery Mode Resonators for Metrological Applications

NASA Technical Reports Server (NTRS)

Chembo, Yanne K.; Baumgartel, Lukas; Grudinin, Ivan; Strekalov, Dmitry; Thompson, Robert; Yu, Nan

2012-01-01

Whispering gallery mode resonators are attracting increasing interest as promising frequency reference cavities. Unlike commonly used Fabry-Perot cavities, however, they are filled with a bulk medium whose properties have a significant impact on the stability of its resonance frequencies. In this context that has to be reduced to a minimum. On the other hand, a small monolithic resonator provides opportunity for better stability against vibration and acceleration. this feature is essential when the cavity operates in a non-laboratory environment. In this paper, we report a case study for a crystalline resonator, and discuss the a pathway towards the inhibition of vibration-and acceleration-induced frequency fluctuations.

Possibility of measuring the Abraham force using whispering gallery modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brevik, I.; Ellingsen, S. A.

2010-06-15

Critical experimental tests of the time-dependent Abraham force in phenomenological electrodynamics are scarce. In this paper, we analyze the possibility of making use of intensity-modulated whispering gallery modes in a microresonator for this purpose. Systems of this kind appear attractive, as the strong concentration of electromagnetic fields near the rim of the resonator serves to enhance the Abraham torque exerted by the field. We analyze mainly spherical resonators, although as an introductory step we consider also the cylinder geometry. The orders of magnitude of the Abraham torques are estimated by inserting reasonable and common values for the various input parameters.more » As expected, the predicted torques turn out to be very small, although probably not beyond reach experimentally. Our main idea is essentially a generalization of the method used by G. B. Walker et al.[Can. J. Phys. 53, 2577 (1975)] for low-frequency fields, to the optical case.« less

Studies of geometrical profiling in fabricated tapered optical fibers using whispering gallery modes spectroscopy

NASA Astrophysics Data System (ADS)

Kavungal, Vishnu; Farrell, Gerald; Wu, Qiang; Kumar Mallik, Arun; Semenova, Yuliya

2018-03-01

This paper experimentally demonstrates a method for geometrical profiling of asymmetries in fabricated thin microfiber tapers with waist diameters ranging from ∼10 to ∼50 μm with submicron accuracy. The method is based on the analysis of whispering gallery mode resonances excited in cylindrical fiber resonators as a result of evanescent coupling of light propagating through the fiber taper. The submicron accuracy of the proposed method has been verified by SEM studies. The method can be applied as a quality control tool in fabrication of microfiber based devices and sensors or for fine-tuning of microfiber fabrication set-ups.

Highly efficient optical power transfer to whispering-gallery modes by use of a symmetrical dual-coupling configuration.

PubMed

Cai, M; Vahala, K

2000-02-15

We report that greater than 99.8% optical power transfer to whispering-gallery modes was achieved in fused-silica microspheres by use of a dual-tapered-fiber coupling method. The intrinsic cavity loss and the taper-to-sphere coupling coefficient are inferred from the experimental data. It is shown that the low intrinsic cavity loss and the symmetrical dual-coupling structure are crucial for obtaining the high coupling efficiency.

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

PubMed Central

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

Graded-Index "Whispering-Gallery" Optical Microresonators

NASA Technical Reports Server (NTRS)

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

2006-01-01

Graded-index-of-refraction dielectric optical microresonators have been proposed as a superior alternative to prior dielectric optical microresonators, which include microspheres and microtori wherein electromagnetic waves propagate along circumferential paths in "whispering-gallery" modes. The design and method of fabrication of the proposed microresonators would afford improved performance by exploiting a combination of the propagation characteristics of the whisperinggallery modes and the effect of a graded index of refraction on the modes.

Hybrid systems of AlInP microdisks and colloidal CdSe nanocrystals showing whispering-gallery modes at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelow, Christian; Weising, Simon; Bonatz, Dennis

2014-09-01

We report on the realization of hybrid systems composed of passive optical microdisk resonators prepared from epitaxial layer systems and nanocrystal quantum emitters synthesized by colloidal chemistry. The AlInP disk material allows for the operation in the visible range, as probed by CdSe-based nanocrystals. Photoluminescence spectra at room temperature reveal sets of whispering-gallery modes consistent with finite-difference time-domain simulations. In the experiments, a special sample geometry renders it possible to detect resonant optical modes perpendicular to the disk plane.

Single virus and nanoparticle size spectrometry by whispering-gallery-mode microcavities

NASA Astrophysics Data System (ADS)

Zhu, Jiangang; Kaya Özdemir, Şahin; He, Lina; Chen, Da-Ren; Yang, Lan

2011-08-01

Detecting and characterizing single nanoparticles and airborne viruses are of paramount importance for disease control and diagnosis, for environmental monitoring, and for understanding size dependent properties of nanoparticles for developing innovative products. Although single particle and virus detection have been demonstrated in various platforms, single-shot size measurement of each detected particle has remained a significant challenge. Here, we present a nanoparticle size spectrometry scheme for label-free, real-time and continuous detection and sizing of single Influenza A virions, polystyrene and gold nanoparticles using split whispering-gallery-modes (WGMs) in an ultra-high-Q resonator. We show that the size of each particle and virion can be measured as they continuously bind to the resonator one-by-one, eliminating the need for ensemble measurements, stochastic analysis or imaging techniques employed in previous works. Moreover, we show that our scheme has the ability to identify the components of particle mixtures.

Sapphire Whispering Gallery Thermometer

NASA Astrophysics Data System (ADS)

Strouse, G. F.

2007-12-01

An innovative sapphire whispering gallery thermometer (SWGT) is being explored at the National Institute of Standards and Technology (NIST) as a potential replacement for a standard platinum resistance thermometer (SPRT) for industrial applications that require measurement uncertainties of ≤ 10 mK. The NIST SWGT uses a synthetic sapphire monocrystalline disk configured as a uniaxial, dielectric resonator with whispering gallery modes between 14 GHz and 20 GHz and with Q-factors as large as 90,000. The prototype SWGT stability at the ice melting point (0°C) is ≤ 1 mK with a frequency resolution equivalent to 0.05 mK. The prototype SWGT measurement uncertainty ( k= 1) is 10 mK from 0°C to 100°C for all five resonance modes studied. These results for the SWGT approach the capabilities of industrial resistance thermometers. The SWGT promises greatly increased resistance to mechanical shock relative to SPRTs, over the range from -196°C to 500°C while retaining the low uncertainties needed by secondary calibration laboratories. The temperature sensitivity of the SWGT depends upon a well-defined property (the refractive index at microwave frequencies) and the thermal expansion of a pure material. Therefore, it is expected that SWGTs can be calibrated over a wide temperature range using a reference function, along with deviations measured at a few fixed points. This article reports the prototype SWGT stability, resolution, repeatability, and the temperature dependence of five whispering gallery resonance frequencies in the range from 0°C to 100°C.

Numerical simulation of eigenmodes of ring and race-track optical microresonators

NASA Astrophysics Data System (ADS)

Raskhodchikov, A. V.; Raskhodchikov, D. V.; Scherbak, S. A.; Lipovskii, A. A.

2017-11-01

We have performed a numerical study of whispering gallery modes of ring and race-track optical microresonators. Mode excitation was considered and their spectra and electromagnetic field distributions were calculated via numerical solution of the Helmholtz equation. We pay additional attention to features of eigenmodes in race-tracks in contrast with ring resonators. Particularly, we demonstrate that modes in race-tracks are not “classic” WGM in terms of total internal reflection from a single boundary, and an inner boundary is essential for their formation. The dependence of effective refractive index of race-tracks modes on the resonator width is shown.

Label-free, single-object sensing with a microring resonator: FDTD simulation.

PubMed

Nguyen, Dan T; Norwood, Robert A

2013-01-14

Label-free, single-object sensing with a microring resonator is investigated numerically using the finite difference time-domain (FDTD) method. A pulse with ultra-wide bandwidth that spans over several resonant modes of the ring and of the sensing object is used for simulation, enabling a single-shot simulation of the microring sensing. The FDTD simulation not only can describe the circulation of the light in a whispering-gallery-mode (WGM) microring and multiple interactions between the light and the sensing object, but also other important factors of the sensing system, such as scattering and radiation losses. The FDTD results show that the simulation can yield a resonant shift of the WGM cavity modes. Furthermore, it can also extract eigenmodes of the sensing object, and therefore information from deep inside the object. The simulation method is not only suitable for a single object (single molecule, nano-, micro-scale particle) but can be extended to the problem of multiple objects as well.

Highly sensitive detection of nanoparticles with a self-referenced and self-heterodyned whispering-gallery Raman microlaser.

PubMed

Özdemir, Şahin Kaya; Zhu, Jiangang; Yang, Xu; Peng, Bo; Yilmaz, Huzeyfe; He, Lina; Monifi, Faraz; Huang, Steven He; Long, Gui Lu; Yang, Lan

2014-09-16

Optical whispering-gallery-mode resonators (WGMRs) have emerged as promising platforms for label-free detection of nano-objects. The ultimate sensitivity of WGMRs is determined by the strength of the light-matter interaction quantified by quality factor/mode volume, Q/V, and the resolution is determined by Q. To date, to improve sensitivity and precision of detection either WGMRs have been doped with rare-earth ions to compensate losses and increase Q or plasmonic resonances have been exploited for their superior field confinement and lower V. Here, we demonstrate, for the first time to our knowledge, enhanced detection of single-nanoparticle-induced mode splitting in a silica WGMR via Raman gain-assisted loss compensation and WGM Raman microlaser. In particular, the use of the Raman microlaser provides a dopant-free, self-referenced, and self-heterodyned scheme with a detection limit ultimately determined by the thermorefractive noise. Notably, we detected and counted individual nanoparticles with polarizabilities down to 3.82 × 10(-6) μm(3) by monitoring a heterodyne beatnote signal. This level of sensitivity is achieved without exploiting plasmonic effects, external references, or active stabilization and frequency locking. Single nanoparticles are detected one at a time; however, their characterization by size or polarizability requires ensemble measurements and statistical averaging. This dopant-free scheme retains the inherited biocompatibility of silica and could find widespread use for sensing in biological media. The Raman laser and operation band of the sensor can be tailored for the specific sensing environment and the properties of the targeted materials by changing the pump laser wavelength. This scheme also opens the possibility of using intrinsic Raman or parametric gain for loss compensation in other systems where dissipation hinders progress and limits applications.

Detecting single viruses and nanoparticles using whispering gallery microlasers.

PubMed

He, Lina; Ozdemir, Sahin Kaya; Zhu, Jiangang; Kim, Woosung; Yang, Lan

2011-06-26

There is a strong demand for portable systems that can detect and characterize individual pathogens and other nanoscale objects without the use of labels, for applications in human health, homeland security, environmental monitoring and diagnostics. However, most nanoscale objects of interest have low polarizabilities due to their small size and low refractive index contrast with the surrounding medium. This leads to weak light-matter interactions, and thus makes the label-free detection of single nanoparticles very difficult. Micro- and nano-photonic devices have emerged as highly sensitive platforms for such applications, because the combination of high quality factor Q and small mode volume V leads to significantly enhanced light-matter interactions. For example, whispering gallery mode microresonators have been used to detect and characterize single influenza virions and polystyrene nanoparticles with a radius of 30 nm (ref. 12) by measuring in the transmission spectrum either the resonance shift or mode splitting induced by the nanoscale objects. Increasing Q leads to a narrower resonance linewidth, which makes it possible to resolve smaller changes in the transmission spectrum, and thus leads to improved performance. Here, we report a whispering gallery mode microlaser-based real-time and label-free detection method that can detect individual 15-nm-radius polystyrene nanoparticles, 10-nm gold nanoparticles and influenza A virions in air, and 30 nm polystyrene nanoparticles in water. Our approach relies on measuring changes in the beat note that is produced when an ultra-narrow emission line from a whispering gallery mode microlaser is split into two modes by a nanoscale object, and these two modes then interfere. The ultimate detection limit is set by the laser linewidth, which can be made much narrower than the resonance linewidth of any passive resonator. This means that microlaser sensors have the potential to detect objects that are too small to be

The relationship between resonance scattering and the formation of an acoustojet under the interaction of ultrasound with a dielectric sphere immersed in water

NASA Astrophysics Data System (ADS)

Minin, I. V.; Minin, O. V.; Tseplyaev, I. S.

2017-08-01

We demonstrated for the first time the influence of the main parameters of dielectric spherical cavity, immersed in water, to transformation of whispering gallery mode into acoustojet (acoustic jets) by interaction of acoustic plane wave scatterer. It has been shown that the relative speed of sound in the material, the relative density of the material and the radius of particle significantly affect the condition for the formation of WGM resonance. However, the "more sensitive" parameter is the relative speed of sound.

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

NASA Astrophysics Data System (ADS)

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.

Creating and Probing Graphene Electron Optics with Local Scanning Probes

NASA Astrophysics Data System (ADS)

Stroscio, Joseph

Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

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DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, Hyeonjun; Hyun, Jerome K.; Chung, Kunook

Lasing from long semiconductor nanorods is dictated by Fabry-Perot (FP) resonances whereas that from large-diameter microrods is determined by whispering gallery modes (WGMs). Lengths and diameters intermediate between the two systems represent an important size regime for photonics and electronics, but have not been studied in detail. Here, we report on the detection of FP and WGM lasing emissions from a single GaN microrod, and demonstrate the ability to switch between the two lasing mechanisms by translating the excitation beam along the microrod. The competition between FP and WGM-type lasing was studied by finite-difference time-domain simulation and statistical analysis bymore » measuring microrods of various diameters. Finally, control over the relative lasing intensities originating from either FPs or WGMs was demonstrated by tuning the polarization of the emission.« less

Robust label-free biosensing using microdisk laser arrays with on-chip references.

PubMed

Wondimu, S F; Hippler, M; Hussal, C; Hofmann, A; Krämmer, S; Lahann, J; Kalt, H; Freude, W; Koos, C

2018-02-05

Whispering-gallery mode (WGM) microdisk lasers show great potential for highly sensitive label-free detection in large-scale sensor arrays. However, when used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. Here we demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching. The technique relies on reference structures protected by locally dispensed passivation materials, and can be scaled to extended arrays of hundreds of devices. We prove the viability of the concept in a series of experiments, demonstrating robust and sensitive label-free detection over a wide range of constant or continuously varying temperatures. To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift.

Optothermal transport behavior in whispering gallery mode optical cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltani, Soheil; Armani, Andrea M., E-mail: armani@usc.edu; Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089

Over the past century, whispering gallery mode optical cavities have enabled numerous advances in science and engineering, such as discoveries in quantum mechanics and non-linear optics, as well as the development of optical gyroscopes and add drop filters. One reason for their widespread appeal is their ability to confine light for long periods of time, resulting in high circulating intensities. However, when sufficiently large amounts of optical power are coupled into these cavities, they begin to experience optothermal or photothermal behavior, in which the optical energy is converted into heat. Above the optothermal threshold, the resonance behavior is no longermore » solely defined by electromagnetics. Previous work has primarily focused on the role of the optothermal coefficient of the material in this instability. However, the physics of this optothermal behavior is significantly more complex. In the present work, we develop a predictive theory based on a generalizable analytical expression in combination with a geometry-specific COMSOL Multiphysics finite element method model. The simulation couples the optical and thermal physics components, accounting for geometry variations as well as the temporal and spatial profile of the optical field. To experimentally verify our theoretical model, the optothermal thresholds of a series of silica toroidal resonant cavities are characterized at different wavelengths (visible through near-infrared) and using different device geometries. The silica toroid offers a particularly rigorous case study for the developed optothermal model because of its complex geometrical structure which provides multiple thermal transport paths.« less

Morphology-Dependent Resonances and Their Applications to Sensing in Aerospace Environments

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Otugen, M.V.

2009-01-01

This paper reviews recent developments in Morphology-Dependent Resonance (MDR)-based sensors for aerospace applications. The sensor concept is based on the detection of small shifts of optical resonances (also called the whispering gallery modes or WGM) of dielectric spheres caused by external effects. Recent developments in MRD-based micro-optical sensors for temperature, force, pressure, and concentration are discussed. In addition to the experimental configurations used in each type of prototype sensor, a brief overview is also given for analytical approaches to describe the sensor principle.

Superpersistent currents and whispering gallery modes in relativistic quantum chaotic systems

PubMed Central

Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso

2015-01-01

Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems. PMID:25758591

Superpersistent currents and whispering gallery modes in relativistic quantum chaotic systems.

PubMed

Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso

2015-03-11

Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems.

A Fiber-Tip Label-Free Biological Sensing Platform: A Practical Approach toward In-Vivo Sensing

PubMed Central

François, Alexandre; Reynolds, Tess; Monro, Tanya M.

2015-01-01

The platform presented here was devised to address the unmet need for real time label-free in vivo sensing by bringing together a refractive index transduction mechanism based on Whispering Gallery Modes (WGM) in dye doped microspheres and Microstructured Optical Fibers. In addition to providing remote excitation and collection of the WGM signal, the fiber provides significant practical advantages such as an easy manipulation of the microresonator and the use of this sensor in a dip sensing architecture, alleviating the need for a complex microfluidic interface. Here, we present the first demonstration of the use of this approach for biological sensing and evaluate its limitation in a sensing configuration deprived of liquid flow which is most likely to occur in an in vivo setting. We also demonstrate the ability of this sensing platform to be operated above its lasing threshold, enabling enhanced device performance. PMID:25585104

Combining an Optical Resonance Biosensor with Enzyme Activity Kinetics to Understand Protein Adsorption and Denaturation

PubMed Central

Wilson, Kerry A.; Finch, Craig A.; Anderson, Phillip; Vollmer, Frank; Hickman, James J.

2014-01-01

Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was used to study a catalytic enzyme’s adsorption processes on different silane modified glass substrates (plain glass control, DETA, 13F, and SiPEG). The WGM sensor was able to obtain high resolution kinetic data of glucose oxidase (GO) adsorption with sensitivity of adsorption better than that possible with SPR. The kinetic data, in combination with a functional assay of the enzyme activity, was used to test hypotheses on adsorption mechanisms. By fitting numerical models to the WGM sensograms for protein adsorption, and by confirming numerical predictions of enzyme activity in a separate assay, we were able to identify mechanisms for GO adsorption on different alkylsilanes and infer information about the adsorption of protein on nanostructured surfaces. PMID:25453976

Combining an optical resonance biosensor with enzyme activity kinetics to understand protein adsorption and denaturation.

PubMed

Wilson, Kerry A; Finch, Craig A; Anderson, Phillip; Vollmer, Frank; Hickman, James J

2015-01-01

Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was used to study a catalytic enzyme's adsorption processes on different silane modified glass substrates (plain glass control, DETA, 13 F, and SiPEG). The WGM sensor was able to obtain high resolution kinetic data of glucose oxidase (GO) adsorption with sensitivity of adsorption better than that possible with SPR. The kinetic data, in combination with a functional assay of the enzyme activity, was used to test hypotheses on adsorption mechanisms. By fitting numerical models to the WGM sensograms for protein adsorption, and by confirming numerical predictions of enzyme activity in a separate assay, we were able to identify mechanisms for GO adsorption on different alkylsilanes and infer information about the adsorption of protein on nanostructured surfaces. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Biosensing in a microelectrofluidic system using optical whispering-gallery mode spectroscopy

PubMed Central

Huang, Lei; Guo, Zhixiong

2011-01-01

Label-free detection of biomolecules using an optical whispering-gallery mode sensor in a microelectrofluidic channel is simulated. Negatively charged bovine serum albumin is considered as the model protein analyte. The analyte transport in aqueous solution is controlled by an externally applied electrical field. The finite element method is employed for solving the equations of the charged species transport, the Poisson equation of electric potential, the equations of conservation of momentum and energy, and the Helmholtz equations of electromagnetic waves. The adsorption process of the protein molecules on the microsensor head surface is monitored by the resonance frequency shifts. Frequency shift caused by temperature variation due to Joule heating is analyzed and found to be negligible. The induced shifts behave in a manner similar to Langmuir-like adsorption kinetics; but the time constant increases due to the presence of the external electrical field. A correlation of the frequency shift, the analyte feed concentration in the solution, and the applied voltage gradient is obtained, in which an excellent linear relationship between the frequency shift and the analyte concentration is revealed. The applied voltage gradient enhances significantly the analyte concentration in the vicinity of the sensor surface; thus, the sensor sensitivity which has a power function of the voltage gradient with exponent 2.85 in the controlled voltage range. Simulated detection of extremely low protein concentration to the pico-molar level is carried out. PMID:22662041

Spatially resolved surface-related exciton polariton dynamics in a single ZnO tetrapod

NASA Astrophysics Data System (ADS)

Sun, Fangfang; Sun, Liaoxin; Zhang, Bo; Wang, Hailong

2018-02-01

The band-edge emission lifetime in a single ZnO tetrapod is studied by using the time-resolved confocal micro-photoluminescence (TR- μPL) spectroscopic technique at room temperature. By performing μPL and TR- μPL mapping along the tapered arm of tetrapod, we observe whispering gallery mode (WGM) polaritons and find that the predominant radiative lifetime of exciton polaritons decreases linearly with increasing the surface-to-volume ratio of the sample. This behavior is ascribed to the surface electric field induced enhancement of the radiative decay rate of the exciton-like polaritons coupling with LO phonons.

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

PubMed

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.

Tapered optical fiber waveguide coupling to whispering gallery modes of liquid crystal microdroplet for thermal sensing application.

PubMed

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

2017-01-23

We demonstrate efficient coupling to the optical whispering gallery modes (WGMs) of nematic liquid crystal (NLC) microdroplets immersed in an immiscible aqueous environment. An individual NLC microdroplet, confined at the tip of a microcapillary, was coupled via a tapered optical fiber waveguide positioned correctly within its vicinity. Critical coupling of the taper-microdroplet system was facilitated by adjusting the gap between the taper and the microdroplet to change the overlap of the evanescent electromagnetic fields; efficient and controlled power transfer from the taper waveguide to the NLC microdroplet is indeed possible via the proposed technique. We also found that NLC microdroplets can function as highly sensitive thermal sensors: A maximum temperature sensitivity of 267.6 pm/°C and resolution of 7.5 × 10^-2 °C were achieved in a 78-μm-diameter NLC microdroplet.

Generation of Optical Combs in a WGM Resonator from a Bichromatic Pump

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Yu, Nan; Matsko, Andrey B.

2010-01-01

Optical combs generated by a monolithic resonator with Kerrmedium can be used in a number of applications, including orbital clocks and frequency standards of extremely high accuracy, such as astronomy, molecular spectroscopy, and the like. The main difficulty of this approach is the relatively high pump power that has to be used in such devices, causing undesired thermorefractive effects, as well as stimulated Raman scattering, and limiting the optical comb quality and utility. In order to overcome this problem, this innovation uses a different approach to excitation of the nonlinear oscillations in a Kerr-nonlinear whispering gallery mode (WGM) resonator and generation of the optical comb. By coupling to the resonator two optical pump frequencies instead of just one, the efficiency of the comb source can be increased considerably. It therefore can operate in a lowerpower regime where the undesirable effects are not present. This process does not have a power threshold; therefore, the new optical component can easily be made strong enough to generate further components, making the optical comb spread in a cascade fashion. Additionally, the comb spacing can be made in an arbitrary number of the resonator free spectral ranges (FSR). The experimental setup for this innovation used a fluorite resonator with OMEGA= 13.56 GHz. This material has very low dispersion at the wavelength of 1.5 microns, so the resonator spectrum around this wavelength is highly equidistant. Light was coupled in and out of the resonator using two optical fibers polished at the optimal coupling angle. The gap between the resonator and the fibers, affecting the light coupling and the resonator loading, was controlled by piezo positioners. The light from the input fiber that did not go into the resonator reflected off of its rim, and was collected by a photodetector. This enabled observation and measurement of the (absorption) spectrum of the resonator. The input fiber combined light from two

Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

PubMed Central

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

2016-01-01

We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated. PMID:27121151

MoMLA: From Panel to Gallery

ERIC Educational Resources Information Center

Vitanza, Victor, Ed.; Kuhn, Virginia, Ed.

2013-01-01

The work presented here in this "Panel to Gallery" was originally produced and assembled for the 2012 Modern Language Association Conference in Seattle, Washington. Similar to "From Gallery to Webtext", the event Victor curated for the 2006 College Composition and Communication Conference, this "Panel to Gallery" event at MLA set aside the…

Cascading second-order nonlinear processes in a lithium niobate-on-insulator microdisk.

PubMed

Liu, Shijie; Zheng, Yuanlin; Chen, Xianfeng

2017-09-15

Whispering-gallery-mode (WGM) microcavities are very important in both fundamental science and practical applications, among which on-chip second-order nonlinear microresonators play an important role in integrated photonic functionalities. Here we demonstrate resonant second-harmonic generation (SHG) and cascaded third-harmonic generation (THG) in a lithium niobate-on-insulator (LNOI) microdisk resonator. Efficient SHG in the visible range was obtained with only several mW input powers at telecom wavelengths. THG was also observed through a cascading process, which reveals simultaneous phase matching and strong mode coupling in the resonator. Cascading of second-order nonlinear processes gives rise to an effectively large third-order nonlinearity, which makes on-chip second-order nonlinear microresonators a promising frequency converter for integrated nonlinear photonics.

Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asano, M.; Ikuta, R.; Imoto, N.

We report controllable manipulation of slow and fast light in a whispering-gallery-mode microtoroid resonator fabricated from Erbium (Er{sup 3+}) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed inmore » the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.« less

Biochemical component identification by plasmonic improved whispering gallery mode optical resonance based sensor

NASA Astrophysics Data System (ADS)

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

2014-05-01

Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements, antibiotic of different generation etc. in both single and multi component solutions under varied in wide range concentration analyzed on the light scattering parameters of whispering gallery mode optical resonance based sensor are represented. Multiplexing on parameters and components has been realized using developed fluidic sensor cell with fixed in adhesive layer dielectric microspheres and data processing. Biochemical component identification has been performed by developed network analysis techniques. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis. Novel technique based on optical resonance on microring structures, plasmon resonance and identification tools has been developed. To improve a sensitivity of microring structures microspheres fixed by adhesive had been treated previously by gold nanoparticle solution. Another technique used thin film gold layers deposited on the substrate below adhesive. Both biomolecule and nanoparticle injections caused considerable changes of optical resonance spectra. Plasmonic gold layers under optimized thickness also improve parameters of optical resonance spectra. Biochemical component identification has been also performed by developed network analysis techniques both for single and for multi component solution. So advantages of plasmon enhancing optical microcavity resonance with multiparameter identification tools is used for development of a new platform for ultra sensitive label-free biomedical sensor.

Landslide Caused Damages in a Gallery

NASA Astrophysics Data System (ADS)

Poisel, R.; Mair am Tinkhof, K.; Preh, A.

2016-06-01

On October 5th, 2010, cracks were found in a gallery 1.8 m high and 1.4 m wide. The gallery is 100 years old, runs parallel to a valley flank and was excavated in a tectonically strongly stressed, weathered and slightly dipping sandwich of clayey shales, sandstones and marls. The cracks in the roof as well as in the invert ran parallel to the axis of the gallery. Monitoring showed that crack widths were increasing 1.5 mm per year, sidewall distances were increasing 3.5 mm per year, whereas the height of the gallery was decreasing 2.5 mm per year. After eliminating several possible causes of cracking, a landslide producing the damages had to be taken into consideration. Monitoring of the valley flank surface as well as inclinometer readings revealed that a landslide was occurring, loading the gallery lining. Most probably the landslide had been reactivated by excessive rainfall in 2009 as well as by works for the renewal of a weir in the valley bottom. As stabilization of the slope was not an option for several reasons, it was decided to replace the gallery by a new one deeper inside the slope, which will be ready for operation in 2017. Thus the old gallery has to be kept in operation till then and it was decided to reinforce the old gallery by a heavily reinforced shotcrete lining 10 cm thick. As slope displacements went on, cracks in the shotcrete lining developed with a completely different pattern: in the section where the gallery lies completely in the landslide shear zone no cracks formed until now due to heavy reinforcement, whereas in the transition sections stable ground-landslide and landslide-stable ground diagonal tension cracks in the roof due to shear by the landslide developed. Numerical models showed that cracking and spalling of the shotcrete lining would occur only after some centimetres of additional displacements of the slope, which hopefully will not occur before 2017.

Surface wave resonance and chirality in a tubular cavity with metasurface design

NASA Astrophysics Data System (ADS)

Qin, Yuzhou; Fang, Yangfu; Wang, Lu; Tang, Shiwei; Sun, Shulin; Liu, Zhaowei; Mei, Yongfeng

2018-06-01

Optical microcavities with whispering-gallery modes (WGMs) have been indispensable in both photonic researches and applications. Besides, metasurfaces, have attracted much attention recently due to their strong abilities to manipulate electromagnetic waves. Here, combining these two optical elements together, we show a tubular cavity can convert input propagating cylindrical waves into directed localized surface waves (SWs), enabling the circulating like WGMs along the wall surface of the designed tubular cavity. Finite element method (FEM) simulations demonstrate that such near-field WGM shows both large chirality and high local field. This work may stimulate interesting potential applications in e.g. directional emission, sensing, and lasing.

Plasmonic improvement of microcavity biomedical sensor spectroscopic characteristics

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas; Ghadiri, Reza

2014-03-01

New opportunity to improve a sensetivity of a label-free biomolecule detection in sensing systems based on microcavity evanescent wave optical sensors has been recently found and is being under intensive development. Novel technique based on combination of optical resonance on microring structures with plasmon resonance. Recently developed tools based on neural network data processing can realize real-time identification of biological agents. So combining advantages of plasmon enhancing optical microcavity resonance with identification tools can give a new platform for ulta sensitive label-free biomedical sensor. Our developed technique used standard glass and polymer microspheres as sensetive elements. They are fixed in the solution flow by adhesive layer on the surface being in the field of evanescence wave. Sensitive layer have been treated by gold nanoparticel (GN) solution. Another technique used thin film gold layers deposited on the substrate below adhesive. The light from a tuneable diode laser is coupled into the microsphere through a prism and was sharply focussed on the single microsphere. Images were recorded by CMOS camera. Normalized by free spectral range resonance shift of whispering gallery mode (WGM) and a relative efficiency of their excitation were used as input data for biomolecule classification. Both biomolecules and NP injection was obtained caused WGM spectra modification. But after NP treatment spectral shift and intensity of WGM resonances in biomolecule solutions increased. WGM resonances in microspheres fixed on substrate with gold layer with optimized layer thickness in biomolecule solutions also had higher intensity and spectra modification then without gold layer.

Coupling of lithium niobate disk resonators to integrated waveguides

NASA Astrophysics Data System (ADS)

Berneschi, S.; Cosi, F.; Nunzi Conti, G.; Pelli, S.; Soria, S.; Righini, G. C.; Dispenza, M.; Secchi, A.

2011-01-01

Whispering gallery mode (WGM) disk resonators fabricated in single crystals can have high Q factors within their transparency bandwidth and may have application both in fundamental and applied optics. Lithium niobate (LN) resonators thanks to their electro-optical properties may be used in particular as tunable filters, modulators, and delay lines. A critical step toward the actual application of these devices is the implementation of a robust and efficient coupling system. High index prisms are typically used for this purpose. In this work we demonstrate coupling to high-Q WGM LN disks from an integrated optical LN waveguide. The waveguides are made by proton exchange in X-cut LN. The disks with diameters of about 5 mm and thickness of 1 mm are made from commercial Z-cut LN wafers by core drilling a cylinder and thereafter polishing the edges into a spheroidal profile. Both resonance linewidth and cavity photon lifetime measurements were performed to calculate the Q factor of the resonator, which is in excess of 108.

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

PubMed

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).

GLCF: Gallery

Science.gov Websites

UMD Land Cover Classification Product External Galleries * ASTER at JPL * AVHRR at JHU * Earth Observatory at NASA * Landsat 7 at USGS * MODIS at NASA * Visible Earth at NASA e-link 4321 Hartwick Building

Neutron whispering gallery

NASA Astrophysics Data System (ADS)

Nesvizhevsky, Valery V.; Voronin, Alexei Yu.; Cubitt, Robert; Protasov, Konstantin V.

2010-02-01

The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for atoms and neutrons. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present for the first time the quantum whispering-gallery effect for cold neutrons. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to the recently discovered gravitationally bound quantum states of neutrons . These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a pure quantum state. Deeply bound whispering-gallery states are long-living and weakly sensitive to surface potential; highly excited states are short-living and very sensitive to the wall potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects.

Polarization Dependent Whispering Gallery Modes in Microspheres

NASA Technical Reports Server (NTRS)

Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

2016-01-01

A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

Heritage Gallery

NASA Technical Reports Server (NTRS)

2002-01-01

Marshall Space Flight Center's (MSFC's) building 4200 hosts a new spaceflight history museum referred to as the Heritage Gallery, allowing employees and visitors alike to have the opportunity to experience history first hand. On display are many models of launch vehicles and spacecraft that have made the center famous. It features a full-scale mockup of the lunar roving vehicle, three built-in multimedia displays, a large theater screen, and two glass cases that house memorabilia such as personal items belonging to Wernher von Braun, MSFC's first Center Director. The new Heritage Gallery features the accomplishments of several past and present members of the Marshall team. Attending the ribbon cutting ceremony are: (left to right) Gerhard Reisig; Cort Durocher, executive director of the American Institute of Aeronautics and Astronautics; Ernst Stuhlinger; Konrad Darnenburg; Werner Dahm; Walter Jacobi; and host of event, Center Director Art Stephenson.

Guards, Galleries, Fortresses, and the Octoplex

ERIC Educational Resources Information Center

Michael, T. S.

2011-01-01

The art gallery problem asks for the maximum number of stationary guards required to protect the interior of a polygonal art gallery with "n" walls. This article explores solutions to this problem and several of its variants. In addition, some unsolved problems involving the guarding of geometric objects are presented.

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

NASA Astrophysics Data System (ADS)

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.

Micro-resonator-based electric field sensors with long durations of sensitivity

NASA Astrophysics Data System (ADS)

Ali, Amir R.

2017-05-01

In this paper, we present a new fabrication method for the whispering gallery mode (WGM) micro-sphere based electric field sensor that which allows for longer time periods of sensitivity. Recently, a WGM-based photonic electric field sensor was proposed using a coupled dielectric microsphere-beam. The external electric field imposes an electrtrostriction force on the dielectric beam, deflecting it. The beam, in turn compresses the sphere causing a shift in its WGM. As part of the fabrication process, the PDMS micro-beams and the spheres are curied at high-temperature (100oC) and subsequently poled by exposing to strong external electric field ( 8 MV/m) for two hours. The poling process allows for the deposition of surface charges thereby increasing the electrostriction effect. This methodology is called curing-then-poling (CTP). Although the sensors do become sufficiently sensitive to electric field, they start de-poling after a short period (within 10 minutes) after poling, hence losing sensitivity. In an attempt to mitigate this problem and to lock the polarization for a longer period, we use an alternate methodology whereby the beam is poled and cured simultaneously (curing-while-poling or CWP). The new fabrication method allows for the retention of polarization (and hence, sensitivity to electric field) longer ( 1500 minutes). An analysis is carried out along with preliminary experiments. Results show that electric fields as small as 100 V/m can be detected with a 300 μm diameter sphere sensor a day after poling.

Biosensing operations based on whispering-gallery-mode optical cavities in single 1.0-µm diameter hexagonal GaN microdisks grown by radio-frequency plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

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

2016-05-01

Biosensing operations based on a whispering-gallery-mode optical cavity in a single hexagonal GaN microdisk of approximately 1.0 µm diameter were demonstrated here. The sharp resonant peak in the photoluminescence spectrum obtained from the microdisk in aqueous sucrose solution redshifts with a change in sucrose concentration. The results indicate that an extremely small microdisk could be used as an optical transducer for sensing sugar, namely, as a biosensor. Furthermore, we investigate the relationship between the diameter of the microdisk and the sensitivity of the biosensor.

Control of Wigner localization and electron cavity effects in near-field emission spectra of In(Ga)P/GaInP quantum-dot structures

NASA Astrophysics Data System (ADS)

Mintairov, A. M.; Kapaldo, J.; Merz, J. L.; Rouvimov, S.; Lebedev, D. V.; Kalyuzhnyy, N. A.; Mintairov, S. A.; Belyaev, K. G.; Rakhlin, M. V.; Toropov, A. A.; Brunkov, P. N.; Vlasov, A. S.; Zadiranov, Yu. M.; Blundell, S. A.; Mozharov, A. M.; Mukhin, I.; Yakimov, M.; Oktyabrsky, S.; Shelaev, A. V.; Bykov, V. A.

2018-05-01

Structural and emission properties of few-electron In(Ga)P/GaInP quantum dots (QDs) representing natural Wigner molecules (WM) and whispering gallery mode (WGM) electron (e ) cavities have been investigated. QD structures were grown using self-organized metal-organic vapor phase epitaxy and deposition from ˜3 to 7 monolayers of InP at 700 °C. Using atomic force microscopy, transmission electron microscopy, near-field scanning optical microscopy (NSOM), and μ -photoluminescence (μ -PL) spectra we obtained In(Ga)P/GaInP QDs having lateral size 80-180 nm, height 5-30 nm, Ga content 0.0-0.4, density 2 -10 μm-2 , and electron population up to 20 and demonstrated control of their density and size distribution. Using high-spatial-resolution low-temperature PL spectra, NSOM imaging, and calculations of charge density distributions we observed Wigner localization and e -cavity effects for a series of dots having quantum confinement ℏ ω0=0.5 -6 meV . We used these data together with time-resolved PL measurements to clarify the effect of Coulomb interaction and WM formation on emission spectra of few-electron QDs. We present direct observation of 2 e , 6 e , and 9 e WMs; 2 e and 4 e WGMs; and Fabry-Perot e modes and establish conditions of e -WGM-cavity formation in these QDs.

Direct measurement for organic solvents diffusion using ultra-sensitive optical resonator

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Elias, Catherine M.

2017-06-01

In this paper, novel techniques using ultra-sensitive chemical optical sensor based on whispering gallery modes (WGM) are proposed through two different configurations. The first one will use a composite micro-sphere, when the solvent interacts with the polymeric optical sensors through diffusion the sphere start to swallow that solvent. In turn, that leads to change the morphology and mechanical properties of the polymeric spheres. Also, these changes could be measured by tracking the WGM shifts. Several experiments were carried out to study the solvent induced WGM shift using microsphere immersed in a solvent atmosphere. It can be potentially used for sensing the trace organic solvents like ethanol and methanol. The second configuration will use a composite beam nitrocellulose composite (NC) structure that acts as a sensing element. In this configuration, a beam is anchored to a substrate in one end, and the other end is compressing the polymeric sphere causing a shift in its WGM. When a chemical molecule is attached to the beam, the resonant frequency of the cantilever will be changed for a certain amount. By sensing this certain resonant frequency change, the existence of a single chemical molecule can be detected. A preliminary experimental model is developed to describe the vibration of the beam structure. The resonant frequency change of the cantilever due to attached mass is examined imperially using acetone as an example. Breath diagnosis can use this configuration in diabetic's diagnosis. Since, solvent like acetone concentration in human breath leads to a quick, convenient, accurate and painless breath diagnosis of diabetics. These micro-optical sensors have been examined using preliminary experiments to fully investigate its response. The proposed chemical sensor can achieve extremely high sensitivity in molecular level.

Adiabatic tapered optical fiber fabrication in two step etching

NASA Astrophysics Data System (ADS)

Chenari, Z.; Latifi, H.; Ghamari, S.; Hashemi, R. S.; Doroodmand, F.

2016-01-01

A two-step etching method using HF acid and Buffered HF is proposed to fabricate adiabatic biconical optical fiber tapers. Due to the fact that the etching rate in second step is almost 3 times slower than the previous droplet etching method, terminating the fabrication process is controllable enough to achieve a desirable fiber diameter. By monitoring transmitted spectrum, final diameter and adiabaticity of tapers are deduced. Tapers with losses about 0.3 dB in air and 4.2 dB in water are produced. The biconical fiber taper fabricated using this method is used to excite whispering gallery modes (WGMs) on a microsphere surface in an aquatic environment. So that they are suitable to be used in applications like WGM biosensors.

Quasi-distributed and wavelength selective addressing of optical micro-resonators based on long period fiber gratings.

PubMed

Farnesi, D; Chiavaioli, F; Baldini, F; Righini, G C; Soria, S; Trono, C; Conti, G Nunzi

2015-08-10

A novel all-in-fiber method for coupling light to high-Q silica whispering gallery mode (WGM) optical micro-resonators is presented, which is based on a pair of long period fiber gratings (LPGs) written in the same silica fiber, along with a thick fiber taper (15-18 μm in waist) in between the LPGs. The proposed coupling structure is robust and can be replicated many times along the same fiber simply cascading LPGs with different bands. Typical Q-factors of the order of 10(8) and total coupling efficiency up to 60% were measured collecting the resonances of microspheres or microbubbles at the fiber end. This approach uniquely allows quasi-distributed and wavelength selective addressing of different micro-resonators along the same fiber.

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

PubMed Central

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

2016-01-01

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. PMID:27314397

Exhibition Spaces/Galleries.

ERIC Educational Resources Information Center

American School & University, 2003

2003-01-01

Presents educational exhibition space/galleries considered outstanding in a competition, which judged the most outstanding learning environments at educational institutions nationwide. Jurors spent two days reviewing projects, highlighting concepts and ideas that made them exceptional. For each citation, the article offers information on the firm,…

Interfacing whispering-gallery microresonators and free space light with cavity enhanced Rayleigh scattering

PubMed Central

Zhu, Jiangang; Özdemir, Şahin K.; Yilmaz, Huzeyfe; Peng, Bo; Dong, Mark; Tomes, Matthew; Carmon, Tal; Yang, Lan

2014-01-01

Whispering gallery mode resonators (WGMRs) take advantage of strong light confinement and long photon lifetime for applications in sensing, optomechanics, microlasers and quantum optics. However, their rotational symmetry and low radiation loss impede energy exchange between WGMs and the surrounding. As a result, free-space coupling of light into and from WGMRs is very challenging. In previous schemes, resonators are intentionally deformed to break circular symmetry to enable free-space coupling of carefully aligned focused light, which comes with bulky size and alignment issues that hinder the realization of compact WGMR applications. Here, we report a new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface, and demonstrate whispering gallery microlaser by free-space optical pumping of an Ytterbium doped silica microtoroid via the scatterers. This new scheme will not only expand the range of applications enabled by WGMRs, but also provide a possible route to integrate them into solar powered green photonics. PMID:25227918

Interfacing whispering-gallery microresonators and free space light with cavity enhanced Rayleigh scattering.

PubMed

Zhu, Jiangang; Özdemir, Sahin K; Yilmaz, Huzeyfe; Peng, Bo; Dong, Mark; Tomes, Matthew; Carmon, Tal; Yang, Lan

2014-09-17

Whispering gallery mode resonators (WGMRs) take advantage of strong light confinement and long photon lifetime for applications in sensing, optomechanics, microlasers and quantum optics. However, their rotational symmetry and low radiation loss impede energy exchange between WGMs and the surrounding. As a result, free-space coupling of light into and from WGMRs is very challenging. In previous schemes, resonators are intentionally deformed to break circular symmetry to enable free-space coupling of carefully aligned focused light, which comes with bulky size and alignment issues that hinder the realization of compact WGMR applications. Here, we report a new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface, and demonstrate whispering gallery microlaser by free-space optical pumping of an Ytterbium doped silica microtoroid via the scatterers. This new scheme will not only expand the range of applications enabled by WGMRs, but also provide a possible route to integrate them into solar powered green photonics.

Optical Sidebands Multiplier

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Yu, Nan

2010-01-01

Optical sidebands have been generated with relative frequency tens to hundreds of GHz by using optical sidebands that are generated in a cascade process in high-quality optical resonators with Kerr nonlinearity, such as whispering gallery mode (WGM) resonators. For this purpose, the WGM resonator needs to be optically pumped at two frequencies matching its resonances. These two optical components can be one or several free spectral ranges (FSRs), equal to approximately 12 GHz, in this example, apart from each other, and can be easily derived from a monochromatic pump with an ordinary EOM (electro-optic modulation) operating at half the FSR frequency. With sufficient nonlinearity, an optical cascade process will convert the two pump frequencies into a comb-like structure extending many FSRs around the carrier frequency. This has a demonstratively efficient frequency conversion of this type with only a few milliwatt optical pump power. The concept of using Kerr nonlinearity in a resonator for non-degenerate wave mixing has been discussed before, but it was a common belief that this was a weak process requiring very high peak powers to be observable. It was not thought possible for this approach to compete with electro-optical modulators in CW applications, especially those at lower optical powers. By using the high-Q WGM resonators, the effective Kerr nonlinearity can be made so high that, using even weak seeding bands available from a conventional EOM, one can effectively multiply the optical sidebands, extending them into an otherwise inaccessible frequency range.

Soilcrust Photo Gallery

Science.gov Websites

Soil Crust Home Crust 101 Advanced Gallery References CCERS Site Links updated: January 30, 2008 images representative of Biological Soil Crusts on the Colorado Plateau. TIF downloads are available for 1 - Open spaces covered by biological soil crusts, a highly specialized community of cyanobacteria

19. MAIN MEETING ROOM LOOKING SOUTH FROM GALLERY. Note coved ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. MAIN MEETING ROOM LOOKING SOUTH FROM GALLERY. Note coved extension of gallery, erected when offices were built on gallery for the use of the Friends Service Committee in 1936. Note also the short stair balusters resulting from the wide modesty stair stringer provided for the women's side. - Twelfth Street Meeting House, 20 South Twelfth Street, Philadelphia, Philadelphia County, PA

Fungus symbionts colonizing the galleries of the ambrosia beetle Platypus quercivorus.

PubMed

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.

Experiences from full-scale rockfall testing of protection gallery

NASA Astrophysics Data System (ADS)

Volkwein, Axel; Fergg, Daniel; Hess, Reto; Schellenberg, Kristian

2017-04-01

Vertical drop tests have been performed at the Swiss Oberalppass road. The planned deconstruction of two avalanche protection galleries enabled a precedent evaluation of one gallery (Parde 1} regarding its capacity against rockfall. The background for this evaluation was also to evaluate an existing model for predicting the protection capacity of a rockfall gallery. Based on this model existing galleries can be evaluated whether their residual capacity is sufficient or if it is necessary to strengthen the structureaccording to the current guidelines. This contribution focusses the conduction of the experiments and the experiences obtained from. The presentation gives details on experimental setup, impact characterization, gallery performance, weather implications, data retrieval and data analysis.According to the limited time span for testing and the resources available, a compact testing series has been setup. Three fields of the gallery were tested with drop weights of 800, 1600 and 3200 kg falling from up to 25 m height. The blocks were lifted by a mobil crane. The concrete roof is supported by columns on the valley side and on the mountainside simply supported on the retention wall. The roof slabspans approximately 6x5 m with a thickness of about 0.60 m and is covered by a soil cushion, which has been unified to 0.40 m thickness previous to the test. Additional wooden columns have been installed at the roof's valleyside to avoid a failure of the concrete columns and to favorize a failure of the roof itself due to bending or punching. The measurements performed consist of high speed video records, accelerations within the impactors and on the bottom surface of the gallery roof.

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

PubMed

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.

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

PubMed

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.

Pompton Lakes Photo Gallery

EPA Pesticide Factsheets

This gallery provides representative photographs of the soil removal and dredging operations within the Pompton Lake Study Area (PLSA) performed starting in 2016 through the present. It will be periodically updated in conjunction with the progress of the

Coral Reefs: A Gallery Program, Grades 7-12.

ERIC Educational Resources Information Center

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…

Fabrication et caracterisation de cavites organiques a modes de galerie

NASA Astrophysics Data System (ADS)

Amrane, Tassadit

The aim of this master project is to combine the high quality factor of whispering gallery optical microcavities with the high photoluminescence efficiency of conjugated polymers. These polymer-cavity composite systems have a great potential for studying the interaction of light and matter in the strong coupling regime. In particular, this system would offer a great opportunity to create a Bose-Einstein condensate of polaritons, the quasi-particles made from a strong interaction between excitons and photons. Organic semiconductors, with their large delocalized excitons, coupled to good whispering gallery cavities with high quality factors and small volumes are an ideal system for this purpose. Two approaches toward this end were explored: in the first approach a pre-existing dielectric whispering gallery cavity was coated with a thin film of conjugated polymer, while in the second one the whispering gallery cavity was fabricated directly with the organic semi-conductor. For testing the first approach, a silica microsphere was dip-coated with copolymer, and the interaction between the whispering gallery modes in the microcavity and the copolymer was studied using photoluminescence spectroscopy. The well-defined resonances obtained at the emission wavelength of the organic material confirm the effective coupling between the photoluminescence and the modes of the cavity. In the second approach, we developed a process to fabricate microdisk cavities with the copolymer. The difficulty in this approach lies in the sensitivity of the organic semiconductor to the microfabrication process. It is critical to avoid dissolving or otherwise altering it during the photolithographic steps. For this purpose a protective polymer, parylene-C, is deposited on the top of the copolymer. This protective polymer was chosen to be transparent at the absorption and emission wavelengths of the copolymer and inert in the solvents used during the different steps of microfabrication. The

Design of organic 3D microresonators with microfluidics coupled to thin-film processes for photonic applications

NASA Astrophysics Data System (ADS)

Huby, N.; Pluchon, D.; Coulon, N.; Belloul, M.; Moreac, A.; Gaviot, E.; Panizza, P.; Bêche, B.

2010-06-01

We report on the design and realization of photonic integrated devices based on 3D organic microresonators (MR) shaped by an applied fluid mechanism technique. Such an interdisciplinary approach has been judiciously achieved by combining microfluidics techniques and thin-film processes, respectively, for the realizations of microfluidic and optical chips. The microfluidic framework with flow rates control allows the fabrication of microresonators with diameters ranging from 30 to 160 μm. The resonance of an isolated sphere in air has been demonstrated by way of a modified Raman spectroscopy devoted to the excitation of Whispering Gallery Modes (WGM). Then the 3D-MR have been integrated onto an organic chip and positioned either close to the extremity of a taper or alongside a rib waveguide. Both devices have proved efficient evanescent coupling mechanisms leading to the excitation of the WGM confined at the surface of the organic 3D-MR. Finally, a band-stop filter has been used to detect the resonance spectra of organic resonators once being integrated. Such spectral resonances have been observed with an integrated configuration and characterized with a Δ λ = 1.4 nm free spectral range (FSR), appearing as stemming from a 78 μm-radius MR structure.

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis

NASA Astrophysics Data System (ADS)

Scholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T.

2015-05-01

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOx μOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis.

PubMed

Scholten, K; Collin, W R; Fan, X; Zellers, E T

2015-05-28

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOxμOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Combining Whispering-Gallery Mode Optical Biosensors with Microfluidics for Real-Time Detection of Protein Secretion from Living Cells in Complex Media.

PubMed

Chen, Ying-Jen; Schoeler, Ulrike; Huang, Chung-Hsuan Benjamin; Vollmer, Frank

2018-05-01

The noninvasive monitoring of protein secretion of cells responding to drug treatment is an effective and essential tool in latest drug development and for cytotoxicity assays. In this work, a surface functionalization method is demonstrated for specific detection of protein released from cells and a platform that integrates highly sensitive optical devices, called whispering-gallery mode biosensors, with precise microfluidics control to achieve label-free and real-time detection. Cell biomarker release is measured in real time and with nanomolar sensitivity. The surface functionalization method allows for antibodies to be immobilized on the surface for specific detection, while the microfluidics system enables detection in a continuous flow with a negligible compromise between sensitivity and flow control over stabilization and mixing. Cytochrome c detection is used to illustrate the merits of the system. Jurkat cells are treated with the toxin staurosporine to trigger cell apoptosis and cytochrome c released into the cell culture medium is monitored via the newly invented optical microfluidic platform. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light coupling into the Whispering Gallery Modes of a fiber array thin film solar cell for fixed partial Sun tracking

PubMed Central

Mariano, Marina; Rodríguez, Francisco J.; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

2014-01-01

We propose the use of whispering gallery mode coupling in a novel configuration based on implementing a thin film cell on the backside of an array of parallel fibers. We performed numerical calculations using the parameters of a thin film organic cell which demonstrate that light coupling becomes more effective as the angle for the incident light relative to the fiber array normal increases up to an optimal angle close to 55 deg. At this angle the power conversion efficiency of the fiber array solar cell we propose becomes 30% times larger than the one from an equivalent planar cell configuration. We demonstrate that the micro fiber array solar cell we propose may perform an effective partial tracking of the sun movement for over 100 degrees without any mechanical help. In addition, in the event that such fiber array cell would be installed with the adequate orientation on a vertical façade, an optimal photon-to-charge conversion would be reached for sunlight incident at 55 deg with respect to the horizon line, very close to the yearly average position for the sun at Latitude of 40 deg.

Mega-pixel PQR laser chips for interconnect, display ITS, and biocell-tweezers OEIC

NASA Astrophysics Data System (ADS)

Kwon, O'Dae; Yoon, J. H.; Kim, D. K.; Kim, Y. C.; Lee, S. E.; Kim, S. S.

2008-02-01

We describe a photonic quantum ring (PQR) laser device of three dimensional toroidal whispering gallery cavity. We have succeeded in fabricating the first genuine mega-pixel laser chips via regular semiconductor technology. This has been realized since the present injection laser emitting surface-normal dominant 3D whispering gallery modes (WGMs) can be operated CW with extremely low operating currents (μA-nA per pixel), together with the lasing temperature stabilities well above 140 deg C with minimal redshifts, which solves the well-known integration problems facing the conventional VCSEL. Such properties unusual for quantum well lasers become usual because the active region, involving vertically confining DBR structure in addition to the 2D concave WGM geometry, induces a 'photonic quantum ring (PQR)-like' carrier distribution through a photonic quantum corral effect. A few applications of such mega-pixel PQR chips are explained as follows: (A) Next-generation 3D semiconductor technologies demand a strategy on the inter-chip and intra-chip optical interconnect schemes with a key to the high-density emitter array. (B) Due to mounting traffic problems and fatalities ITS technology today is looking for a revolutionary change in the technology. We will thus outline how 'SLEEP-ITS' can emerge with the PQR's position-sensing capability. (C) We describe a recent PQR 'hole' laser of convex WGM: Mega-pixel PQR 'hole' laser chips are even easier to fabricate than PQR 'mesa' lasers. Genuine Laguerre-Gaussian (LG) beam patterns of PQR holes are very promising for biocell manipulations like sorting mouse myeloid leukemia (M1s) cells. (D) Energy saving and 3D speckle-free POR laser can outdo LEDs in view of red GaAs and blue GaN devices fabricated recently.

Science Outreach through Art: A Journal Article Cover Gallery

ERIC Educational Resources Information Center

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…

Mode coupling in hybrid square-rectangular lasers for single mode operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Xiu-Wen; Huang, Yong-Zhen, E-mail: yzhuang@semi.ac.cn; Yang, Yue-De

Mode coupling between a square microcavity and a Fabry-Pérot (FP) cavity is proposed and demonstrated for realizing single mode lasers. The modulations of the mode Q factor as simulation results are observed and single mode operation is obtained with a side mode suppression ratio of 46 dB and a single mode fiber coupling loss of 3.2 dB for an AlGaInAs/InP hybrid laser as a 300-μm-length and 1.5-μm-wide FP cavity connected to a vertex of a 10-μm-side square microcavity. Furthermore, tunable single mode operation is demonstrated with a continuous wavelength tuning range over 10 nm. The simple hybrid structure may shed light on practicalmore » applications of whispering-gallery mode microcavities in large-scale photonic integrated circuits and optical communication and interconnection.« less

19. Historic American Building Survey Crocker Art Gallery Collection Copy ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. Historic American Building Survey Crocker Art Gallery Collection Copy from N. P. Goodell, Architect C1879 NORTHWEST CORNER (EAST ELEVATION?) OF 3RD & P ST. (property of Mrs. E. B. Crocker) - Crocker Art Gallery, 216 O Street, Sacramento, Sacramento County, CA

View north of west gallery of inside machine shop 36; ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View north of west gallery of inside machine shop 36; the gallery housed turret, engine and toolroom lathes, small milling machines and drill presses used for machining small parts. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Structure Shop, League Island, Philadelphia, Philadelphia County, PA

Resonant coupling into hybrid 3D micro-resonator devices on organic/biomolecular film/glass photonic structures

NASA Astrophysics Data System (ADS)

Bêche, Bruno; Potel, Arnaud; Barbe, Jérémy; Vié, Véronique; Zyss, Joseph; Godet, Christian; Huby, Nolwenn; Pluchon, David; Gaviot, Etienne

2010-01-01

We have designed and realized an integrated photonic family of micro-resonators (MR) on multilayer SU8/lipidic film/glass materials. Such a family involves hybrid 3D-MR structures composed of spherical glass-MR arranged upon organic pair-SU8-waveguides, an efficient coupling being ensured with a Langmuir-Blodgett Dipalmitoylphosphatidylcholine (DPPC-lipid from Avanti Polar ®) film whose thickness is ranging from 12 to 48 nm. We have characterized such add/drop filters, respectively, in intensity and spectral measurements, and experimentally achieved an evanescent resonant-photonic-coupling between the 3D-MR and the 4-ports structure through the DPPC-gap. Spectral resonances have been measured for 4-whispering gallery-modes (WGM) into such 3D-structures, respectively, characterized with a 0.97 nm free spectral range (FSR) and a high quality Q-factor up to 4.10 4.

A gallery approach for off-angle iris recognition

NASA Astrophysics Data System (ADS)

Karakaya, Mahmut; Yoldash, Rashiduddin; Boehnen, Christopher

2015-05-01

It has been proven that hamming distance score between frontal and off-angle iris images of same eye differs in iris recognition system. The distinction of hamming distance score is caused by many factors such as image acquisition angle, occlusion, pupil dilation, and limbus effect. In this paper, we first study the effect of the angle variations between iris plane and the image acquisition systems. We present how hamming distance changes for different off-angle iris images even if they are coming from the same iris. We observe that increment in acquisition angle of compared iris images causes the increment in hamming distance. Second, we propose a new technique in off-angle iris recognition system that includes creating a gallery of different off-angle iris images (such as, 0, 10, 20, 30, 40, and 50 degrees) and comparing each probe image with these gallery images. We will show the accuracy of the gallery approach for off-angle iris recognition.

The Authors Gallery: A Meaningful Integration of Technology and Writing

ERIC Educational Resources Information Center

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…

The Habitable Zone Gallery and its Applications

NASA Astrophysics Data System (ADS)

Gelino, Dawn M.; Kane, S. R.

2012-05-01

The Habitable Zone Gallery (www.hzgallery.org) is a service to the exoplanet community which provides Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table, a plot with the period and eccentricity of each of the planets with respect to their time spent in the HZ, a gallery of known systems which plot the orbits and the location of the HZ with respect to those orbits, and orbital movies. Here we discuss various educational and scientific applications of the site such as target selection, exploring planets with eccentric orbits, and investigating habitability.

Dielectric micro-resonator-based opto-mechanical systems for sensing applications

NASA Astrophysics Data System (ADS)

Ali, Amir Roushdy

In recent years, whispering gallery mode (WGM), or morphology dependent optical resonances (MDR) of dielectric micro-resonators have attracted interest with proposed applications in a wide range of areas due to the high optical quality factors, Q, they can exhibit (reaching ~ 10. 9 for silica spheres). Micro-resonator WGMs have been used in applications that include those in spectroscopy, micro-cavity laser technology, optical communications (switching, filtering and multiplexing), sensors technologies and even chemical and biological sensing. The WGM of these dielectric micro-resonators are highly sensitive to morphological changes (such as the size, shape, or refractive index) of the resonance cavity and hence, can be tuned by causing a minute change in the physical condition of the surrounding. In this dissertation, we have been creating opto-mechanical systems, which at their most basic, are extraordinarily sensitive sensors. One of the ultimate goals of this dissertation is to develop sensors capable of detecting the extremely small electric field changes. To improve the performance of the sensors, we couple a polymer cantilever beam to a dielectric micro-resonator. The eventual use of such ultra sensitive electric filed sensors could include neural-machine interfaces for advanced prosthetics devices. The work presented here includes a basic analysis and experimental investigations of the electric field sensitivity and range of micro-resonators of several different materials and geometries followed by the electric field sensor design, testing, and characterization. Also, the effects of angular velocity on the WGM shifts of spherical micro-resonators are also investigated. The elastic deformation that is induced on a spinning resonator due to the centrifugal force may lead to a sufficient shift in the optical resonances and therefore interfering with its desirable operational sensor design. Furthermore, this principle could be used for the development of

Tracking Water Diffusion Fronts in a Highly Viscous Aerosol Particle

NASA Astrophysics Data System (ADS)

Bastelberger, Sandra; Krieger, Ulrich; Peter, Thomas

2016-04-01

Field measurements indicate that atmospheric secondary aerosol particles can be present in a highly viscous, glassy state [1]. In contrast to liquid state particles, the gas phase equilibration is kinetically limited and governed by condensed phase diffusion. In recent water diffusion experiments on highly viscous single aerosol particles levitated in an electrodynamic balance (EDB) we observed a characteristic shift behavior of the Mie whispering gallery modes (WGM) indicative of the changing radial structure of the particle, thus providing us with an experimental method to track the diffusion process inside the particle. When a highly viscous, homogeneous particle is exposed to an abrupt increase in relative humidity, the rapid gas phase diffusion and strong concentration dependence of the diffusion coefficient in the condensed phase lead to extremely steep water concentration gradients inside the particle, reminiscent of diffusion fronts. The resulting quasi step-like concentration profile motivates the introduction of a simple core-shell model describing the morphology of the non-equilibrium particle during humidification. The subsequent particle growth and reduction of the shell refractive index can be observed as red and blueshift behavior of the WGM, respectively. The shift pattern can be attributed to a core-shell radius ratio and particle radius derived from model calculations [2]. If supplemented with growth information obtained from the WGM redshift and thermodynamic equilibrium data, we can infer a comprehensive picture of the time evolution of the diffusion fronts in the framework of our core-shell model. The measured time dependent concentration profile is then compared with simulations solving the non-linear diffusion equation [3] [1] Virtanen, A., et al., Nature, 467, 824-827, 2010 [2] Kaiser, T., Schweiger, G., Computers in Physics, Vol. 7, No. 6, 682-686, Nov/Dec 1993 [3] Zobrist, B., Soonsin, V., Luo, B.P., Peter, T. et al., Phys. Chem. Chem

The Art Gallery/La Galeria de Arte: An Exhibition of Transformation.

ERIC Educational Resources Information Center

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…

Theorizing How Art Gallery Interventions Impact People With Dementia and Their Caregivers.

PubMed

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.

Durability of visitable concrete sewer gallery under the effect of domestic wastewater

NASA Astrophysics Data System (ADS)

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.

Connecting Universal Design for Learning with Gallery Tours in Art Museum Education

ERIC Educational Resources Information Center

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…

A Millimeter Wave BPF using WG Mode High Permittivity Dielectric Resonators

NASA Astrophysics Data System (ADS)

Sato, Yosuke; Kogami, Yoshinori; Tomabechi, Yoshiro; Matsumura, Kazuhito

In this paper, a design technique of whispering gallery mode high Q value dielectric disk resonators for a millimeter-wave bandpass filter is described. To minimize the resonator size, some high permittivity materials are used. In this resonator design, unloaded Q value of an interested mode and the higher order modes are calculated and then optimum resonator size for the WG mode dielectric filter is determined. For a designed resonator, the higher order modes are hardly excited while the Q value of the fundamental mode can be maximized. Finally, some 3stage BPFs are constructed at 60GHz by using these designed resonators.

Portrait Gallery Illuminates--Grant's Triumphs, Failures.

ERIC Educational Resources Information Center

Lambert, Robert G., Jr.

The 100th anniversary of Ulysses S. Grant's death was observed on July 23, 1985. The Smithsonian National Portrait Gallery featured an exhibit of Grant portraiture, which covered his life, from its humble beginnings to military and political triumphs and to failures and disappointment. The exhibit included pictures, artifacts, and momentos from…

Polarization Dependent Coupling of Whispering Gallery Modes in Microspheres

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Wrbanek, S.; Floyd, B.; Crotty, M.

2010-01-01

Two sets of resonances in glass microspheres attached to a standard communication-grade single-mode optical fiber have been observed. It has been found that the strength of the resonances depends strongly on the polarization of the coupled light. Furthermore, the position of the resonances in the wavelength domain depends on the polarization of light in the optical fiber with maximum magnitudes shifted by approximately 45 .

The Empirical Spectator and Gallery Education

ERIC Educational Resources Information Center

Fulkova, Marie; Straker, Alison; Jaros, Milan

2004-01-01

This paper examines the onto-epistemic status and understanding of contemporary material culture and of visual art, particularly in the context of gallery education. It does so through a case study of the response of 15 year-old school students in the Czech Republic and in England to a recent photographic exhibition, I.N.R.I., created by artists…

Road to Silicon Microsphere Fabrication and Mode Coupling

DTIC Science & Technology

2014-07-01

from optical fiber onto a microsphere in whispering gallery mode (courtesy of B. Butkus, Biophotonics International [2...Butkus, Biophotonics International [5]). 2 BACKGROUND SILICON MICROSPHERE FABRICATION METHODS Processes for forming spherical structures exist in...Sensitive DNA Detection.” October 2003. Biophotonics International. http://www.rowland.org/rjf/vollmer/images/biophotonics.pdf [6] James E. McDonald

Analysis of nonreciprocal noise based on mode splitting in a high-Q optical microresonator

NASA Astrophysics Data System (ADS)

Yang, Zhaohua; Xiao, Yarong; Huo, Jiayan; Shao, Hui

2018-01-01

The whispering gallery mode optical microresonator offers a high quality factor, which enables it to act as the core component of a high sensitivity resonator optic gyro; however, nonreciprocal noise limits its precision. Considering the Sagnac effect, i.e. mode splitting in high-quality optical micro-resonators, we derive the explicit expression for the angular velocity versus the splitting amount, and verify the sensing mechanism by simulation using finite element method. Remarkably, the accuracy of the angular velocity measurement in the whispering gallery mode optical microresonator with a quality factor of 108 is 106 °/s. We obtain the optimal coupling position of the novel angular velocity sensing system by detecting the output transmittance spectra of different vertical coupling distances and axial coupling positions. In addition, the reason for the nonreciprocal phenomenon is determined by theoretical analysis of the evanescent distribution of a tapered fiber. These results will provide an effective method and a theoretical basis for suppression of the nonreciprocal noise.

Topological Galleries: A High Level User Interface for Topology Controlled Volume Rendering

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 themore » pruning hierarchy. We explore these limitations by providing statistics of feature size as function of depth in the pruning hierarchy of the contour tree.« less

Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

NASA Astrophysics Data System (ADS)

Zhong, Kuo; Song, Kai; Clays, Koen

2018-03-01

In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal) lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs) of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM) inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

Optical micro-bubble resonators as promising biosensors

NASA Astrophysics Data System (ADS)

Giannetti, A.; Barucci, A.; Berneschi, S.; Cosci, A.; Cosi, F.; Farnesi, D.; Nunzi Conti, G.; Pelli, S.; Soria, S.; Tombelli, S.; Trono, C.; Righini, G. C.; Baldini, F.

2015-05-01

Recently, optical micro-bubble resonators (OMBRs) have gained an increasing interest in many fields of photonics thanks to their particular properties. These hollow microstructures can be suitable for the realization of label - free optical biosensors by combining the whispering gallery mode (WGM) resonator properties with the intrinsic capability of integrated microfluidics. In fact, the WGMs are morphology-dependent modes: any change on the OMBR inner surface (due to chemical and/or biochemical binding) causes a shift of the resonance position and reduces the Q factor value of the cavity. By measuring this shift, it is possible to obtain information on the concentration of the analyte to be detected. A crucial step for the development of an OMBR-based biosensor is constituted by the functionalization of its inner surface. In this work we report on the development of a physical and chemical process able to guarantee a good homogeneity of the deposed bio-layer and, contemporary, to preserve a high quality factor Q of the cavity. The OMBR capability of working as bioassay was proved by different optical techniques, such as the real time measurement of the resonance broadening after each functionalization step and fluorescence microscopy.

The Cosmology Gallery: Unity through diversity in a vast and awe-inspiring universe.

NASA Astrophysics Data System (ADS)

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.

Traveling in the Snite Museum: A Gallery Game for Families and Young Children.

ERIC Educational Resources Information Center

Matthias, Diana C. J.; Grey, Richard

This game, designed for use in the Snite Museum of Art, Knott Beckman Gallery, Indiana, focuses on some of the different types of travel depicted in gallery paintings from 16th and 17th century Europe. The questions, with multiple choice answers, encourage viewers to find details of every day life, and to consider whether their meaning is…

Teaching Students to Teach: A Case Study from the Yale University Art Gallery

ERIC Educational Resources Information Center

Manekin, Elizabeth; Williams, Elizabeth

2015-01-01

The way the Yale University Art Gallery engages students and the adult public has shifted profoundly over time, a change reflected in the evolution of the museum's signature Gallery Guide program. Founded in 1998 as an organic, experimental way to better engage Yale students to give lecture-based tours, it is now a structured, well-articulated…

Practice First: Flipped Training for Gallery Educators

ERIC Educational Resources Information Center

Palamara, Andrew

2017-01-01

In recent years, museum educators have urgently explored more dynamic ways to train gallery educators, paid or volunteer, that account for different types of learning styles and teaching practices. This article demonstrates how utilizing a flipped learning model, with online webinars as the basic instructional content, can foster individual and…

Gallery productivity, emergence, and flight activity of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

Treesearch

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...

Demonstration of sub-femtomole sensitivity for small molecules with microsphere ring resonator sensors

NASA Astrophysics Data System (ADS)

White, Ian M.; Oveys, Hesam; Fan, Xudong

2006-02-01

Optical microsphere resonators can function as highly sensitive bio/chemical sensors due to the large Q-factor, which leads to high light-matter interaction. The whispering gallery modes (WGM) arise at the surface of the microsphere, creating a highly enhanced optical field that interacts with matter on or near the microsphere surface. As a result, the spectral position of the WGM is extremely sensitive to refractive index changes near the surface, such as when bio/chemical molecules bind to the sphere. We show the potential feasibility of a microsphere ring resonator as a sensor for small molecules by demonstrating detection of sub-femtomole changes in SiO II molecules at the surface of the microsphere. In this experiment, the silica molecules act as an excellent model for small molecule analytes because of their 60 Dalton molecular weight, and because we know nearly the exact quantity of molecules at the surface, which enables a sensitivity characterization. We measure the spectral shifts in the WGMs when low concentrations of hydrofluoric acid (HF) are added to a solution that is being probed by the microsphere. As the HF molecules break apart the SiO II molecules at the sphere surface, the WGMs shift due to the sub-nano-scale decrease in the size of the microsphere. These calculations show that the sensitivity of this microsphere resonator is on the order of 500 attomoles. Our results will lead to the utilization of optical microspheres for detection of trace quantities of small molecules for such applications as drug discovery, environmental monitoring, and enzyme detection using peptide cleavage.

Species composition, community and population dynamics of two gallery forests from the Brazilian Cerrado domain

PubMed Central

Almado, Roosevelt P; Miazaki, Angela S; Diniz, Écio S; Moreira, Luis C B; Meira-Neto, João A.A.

2016-01-01

Abstract Background To understand the impacts of global changes on future community compositions, knowledge of community dynamics is of crucial importance. To improve our knowledge of community composition, biomass stock and maintenance of gallery forests in the Brazilian Cerrado, we provide two datasets from the 0.5 ha Corrego Fazendinha Gallery Forest Dynamics Plot and the Corrego Fundo Gallery Forest Dynamics Plot situated in the Bom Despacho region, Minas Gerais, Southeastern Brazil. New information We report diameter at breast height, basal area and height measurements of 3417 trees and treelets identified during three censuses in both areas. PMID:27660529

Beam Shaped Single Mode Spiral Lasers

DTIC Science & Technology

2011-12-31

θ// =30° in the plane of the cavity. The measured far-field profiles were in good agreement with simulations (C. Yan et al. Applied Physics Letters...gallery mode lasers with elliptical notched resonators The PI discovered that elliptical resonators with a notch at the boundary support in- plane ...model system, an in- plane beam divergence as small as 6 degrees with a peak optical power of ~ 5 mW at room temperature was been demonstrated. The

Photo Gallery from the Los Angeles River Watershed (California)

EPA Pesticide Factsheets

Photo gallery of the Los Angeles River Watershed area of the Urban Waters Federal Partnership (UWFP) reconnects urban communities with their waterways by improving coordination among federal agencies and collaborating with community-led efforts.

The Portable Art Gallery: Fostering Student Ownership and Meaningful Artmaking through Exhibiting Student Artwork

ERIC Educational Resources Information Center

Gillespie, Jethro

2014-01-01

This article describes how High School Visual Arts Teacher Jethro Gillespie built a portable art gallery for his students--essentially an 8-foot cube made from plywood and lightweight boards that can be assembled with bolts and taken apart in sections. The ceiling pieces of the gallery have track lights, the interior walls have been painted gray,…

The Phosphates of Pleistocene-Holocene Sediments of the Eastern Gallery of Denisova Cave

NASA Astrophysics Data System (ADS)

Shunkov, M. V.; Kulik, N. A.; Kozlikin, M. B.; Sokol, E. V.; Miroshnichenko, L. V.; Ulianov, V. A.

2018-01-01

Authigenic phosphate mineralization was first studied on the territory of Russia on the basis of the Holocene and Pleistocene deposits of Denisova Cave. The formation of phosphates in the eastern gallery is related to biodegradation of the horizons of guano of insectivorous bats, which inhabited the cave in the absence man. The results confirmed the archaeological record of the Holocene and the upper part of Pleistocene sequences of the eastern gallery.

Stable switching among high-order modes in polariton condensates

NASA Astrophysics Data System (ADS)

Sun, Yongbao; Yoon, Yoseob; Khan, Saeed; Ge, Li; Steger, Mark; Pfeiffer, Loren N.; West, Ken; Türeci, Hakan E.; Snoke, David W.; Nelson, Keith A.

2018-01-01

We report multistate optical switching among high-order bouncing-ball modes ("ripples") and whispering-gallery modes ("petals") of exciton-polariton condensates in a laser-generated annular trap. By tailoring the diameter and power of the annular trap, the polariton condensate can be switched among different trapped modes, accompanied by redistribution of spatial densities and superlinear increase in the emission intensities, implying that polariton condensates in this geometry could be exploited for an all-optical multistate switch. A model based on non-Hermitian modes of the generalized Gross-Pitaevskii equation reveals that this mode switching arises from competition between pump-induced gain and in-plane polariton loss. The parameters for reproducible switching among trapped modes have been measured experimentally, giving us a phase diagram for mode switching. Taken together, the experimental result and theoretical modeling advance our fundamental understanding of the spontaneous emergence of coherence and move us toward its practical exploitation.

Shooting Gallery Attendance among IDUs in Tijuana and Ciudad Juarez, Mexico: Correlates, Prevention Opportunities, and the Role of the Environment

PubMed Central

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

10. VIEW WITHIN THE EAST OPERATING GALLERY OF WORK STATION ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. VIEW WITHIN THE EAST OPERATING GALLERY OF WORK STATION WITH MANIPULATOR ARMS. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

Whispering galleries and the control of artificial atoms.

PubMed

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.

5. JL photographer, summer 1978. View in filteration gallery looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. JL photographer, summer 1978. View in filteration gallery looking to filter pits. - Division Avenue Pumping Station & Filtration Plant, West 45th Street and Division Avenue, Cleveland, Cuyahoga County, OH

Museums and art galleries as partners for public health interventions.

PubMed

Camic, Paul M; Chatterjee, Helen J

2013-01-01

The majority of public health programmes are based in schools, places of employment and in community settings. Likewise, nearly all health-care interventions occur in clinics and hospitals. An underdeveloped area for public health-related planning that carries international implications is the cultural heritage sector, and specifically museums and art galleries. This paper presents a rationale for the use of museums and art galleries as sites for public health interventions and health promotion programmes through discussing the social role of these organisations in the health and well-being of the communities they serve. Recent research from several countries is reviewed and integrated into a proposed framework for future collaboration between cultural heritage, health-care and university sectors to further advance research, policy development and evidence-based practice.

Engaging Families in the Galleries Using Design Thinking

ERIC Educational Resources Information Center

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…

14. VIEW IN THE WEST OPERATING GALLERY OF POSTMORTEM CELL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. VIEW IN THE WEST OPERATING GALLERY OF POST-MORTEM CELL WORK STATION AND MANIPULATOR ARMS. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

Nonlinear optical effects in organic microstructures

NASA Astrophysics Data System (ADS)

Novikov, Vladimir B.; Mamonov, Evgeniy A.; Kopylov, Denis A.; Mitetelo, Nikolai V.; Venkatakrishnarao, D.; Narayana, YSLV; Chandrasekar, R.; Murzina, Tatiana V.

2017-05-01

Organic microstructures attract much attention due to their unique properties originating from the design of their shape and optical parameters. In this work we discuss the linear, second- and third-order nonlinear optical effects in arrays and in individual organic microstructures composed by self-assembling technique and formed randomly on top of a solid substrate. The structures under study consist of micro-spheres, -hemispheres or -frustums made of red laser dye and reveal an intense fluorescence (FL) in the visible spectral range. Importantly, that due to a high value of the refractive index and confined geometry, such micro-structures support the excitation of whispering gallery modes (WGM), which brings about strong and spectrally-selected light localization. We show that an amplification of the nonlinear optical effects is observed for these structures as compared to a homogeneous dye film of similar composition. The obtained data are in agreement with the results of the FDTD calculations performed for the structures of different dimensions. Perspectives of application of such type of organic nonlinear microresonators in optical devices are discussed.

What Can The Habitable Zone Gallery Do for You?

NASA Astrophysics Data System (ADS)

Gelino, Dawn M.; Kane, Stephen R.

2014-06-01

The Habitable Zone Gallery (www.hzgallery.org) has been online since August 2011 as a service to the exoplanet community to provide Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table, a plot with the period and eccentricity of each of the planets with respect to their time spent in the HZ, a gallery of known systems which plots the orbits and the location of the HZ with respect to those orbits, and orbital movies. Recently, we have added new features including: implementation of both conservative and optimistic HZs, more user-friendly table and movies, movies for circumbinary planets, and a count of planets whose orbits lie entirely within the system’s HZ. Here we discuss various educational and scientific applications of the site such as target selection, exploring planets with eccentric or circumbinary orbits, and investigating habitability.

What Can the Habitable Zone Gallery Do For You?

NASA Astrophysics Data System (ADS)

Gelino, Dawn M.; Kane, Stephen

2015-12-01

The Habitable Zone Gallery (www.hzgallery.org) came online in August 2011 as a service to the exoplanet community that provides Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table, a plot with the period and eccentricity of each of the planets with respect to their time spent in the HZ, a gallery of known systems which plot the orbits and the location of the HZ with respect to those orbits, and orbital movies. Recently, we have added new features including: implementation of both conservative and optimistic HZs, more user-friendly table and movies, movies for circumbinary planets, and a count of planets whose orbits lie entirely within the system's HZ. Here we discuss various educational and scientific applications of the site such as target selection, exploring planets with eccentric or circumbinary orbits, and investigating habitability.

What Can The Habitable Zone Gallery Do For You?

NASA Astrophysics Data System (ADS)

Gelino, D.

2014-04-01

The Habitable Zone Gallery (www.hzgallery.org) came online in August 2011 as a service to the exoplanet community that provides Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table, a plot with the period and eccentricity of each of the planets with respect to their time spent in the HZ, a gallery of known systems which plot the orbits and the location of the HZ with respect to those orbits, and orbital movies. Recently, we have added new features including: implementation of both conservative and optimistic HZs, more user-friendly table and movies, movies for circumbinary planets, and a count of planets whose orbits lie entirely within the system's HZ. Here we discuss various educational and scientific applications of the site such as target selection, exploring planets with eccentric or circumbinary orbits, and investigating habitability.

16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE SERIES OF MANIPULATOR ARMS ALONG THE LEFT WALL. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

Magnetic field detection using magnetorheological optical resonators

NASA Astrophysics Data System (ADS)

Rubino, Edoardo; Ioppolo, Tindaro

2018-02-01

In this paper, we investigate the feasibility of a magnetic field sensor that is based on a magnetorheological micro-optical resonator. The optical resonator has a spherical shape and a diameter of a few hundred micrometers. The resonator is fabricated by using a polymeric matrix made of polyvinyl chloride (PVC) plastisol with embedded magnetically polarizable micro-particles. When the optical resonator is subjected to an external magnetic field, the morphology (radius and refractive index) of the resonator is perturbed by the magnetic forces acting on it, leading to a shift of the optical resonances also known as whispering gallery modes (WGM). In this study, the effect of a static and harmonic magnetic field, as well as the concentration of the magnetic micro-particles on the optical mode shift is investigated. The optical resonances obtained with the PVC plastisol resonator showed a quality factor of 106 . The dynamical behavior of the optical resonator is investigated in the range between 0 and 200 Hz. The sensitivity of the optical resonator reaches a maximum value for a ratio between micro-particles and the polymeric matrix of 2:1 in weight. Experimental results indicate a sensitivity of 0.297 pm/mT leading to a resolution of 336 μT.

1 million-Q optomechanical microdisk resonators for sensing with very large scale integration

NASA Astrophysics Data System (ADS)

Hermouet, M.; Sansa, M.; Banniard, L.; Fafin, A.; Gely, M.; Allain, P. E.; Santos, E. Gil; Favero, I.; Alava, T.; Jourdan, G.; Hentz, S.

2018-02-01

Cavity optomechanics have become a promising route towards the development of ultrasensitive sensors for a wide range of applications including mass, chemical and biological sensing. In this study, we demonstrate the potential of Very Large Scale Integration (VLSI) with state-of-the-art low-loss performance silicon optomechanical microdisks for sensing applications. We report microdisks exhibiting optical Whispering Gallery Modes (WGM) with 1 million quality factors, yielding high displacement sensitivity and strong coupling between optical WGMs and in-plane mechanical Radial Breathing Modes (RBM). Such high-Q microdisks with mechanical resonance frequencies in the 102 MHz range were fabricated on 200 mm wafers with Variable Shape Electron Beam lithography. Benefiting from ultrasensitive readout, their Brownian motion could be resolved with good Signal-to-Noise ratio at ambient pressure, as well as in liquid, despite high frequency operation and large fluidic damping: the mechanical quality factor reduced from few 103 in air to 10's in liquid, and the mechanical resonance frequency shifted down by a few percent. Proceeding one step further, we performed an all-optical operation of the resonators in air using a pump-probe scheme. Our results show our VLSI process is a viable approach for the next generation of sensors operating in vacuum, gas or liquid phase.

15. GENERAL INTERIOR VIEW LOOKING EAST TOWARDS GALLERY AND FRONT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. GENERAL INTERIOR VIEW LOOKING EAST TOWARDS GALLERY AND FRONT ENTRY (NOTE DOORWAY TO BELL TOWER AT TOP AND CONFESSIONAL BOOTHS TO LEFT REAR) - Sacred Heart Church at Whitemarsh, 16101 Annapolis Road, Bowie, Prince George's County, MD

A gallery of HCMM images

NASA Technical Reports Server (NTRS)

1982-01-01

A gallery of what might be called the ""Best of HCMM'' imagery is presented. These 100 images, consisting mainly of Day-VIS, Day-IR, and Night-IR scenes plus a few thermal inertia images, were selected from the collection accrued in the Missions Utilization Office (Code 902) at the Goddard Space Flight Center. They were selected because of both their pictorial quality and their information or interest content. Nearly all the images are the computer processed and contrast stretched products routinely produced by the image processing facility at GSFC. Several LANDSAT images, special HCMM images made by HCMM investigators, and maps round out the input.

Nest-Gallery Development and Caste Composition of Isolated Foraging Groups of the Drywood Termite, Incisitermes minor (Isoptera: Kalotermitidae)

PubMed Central

Himmi, S. Khoirul; Yoshimura, Tsuyoshi; Yanase, Yoshiyuki; Oya, Masao; Torigoe, Toshiyuki; Akada, Masanori; Imadzu, Setsuo

2016-01-01

An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives. PMID:27455332

Optofluidic ring resonator sensor for sensitive label-free detection of breast cancer antigen CA15-3 in human serum

NASA Astrophysics Data System (ADS)

Zhu, Hongying; Dale, Paul S.; Fan, Xudong

2009-05-01

Breast cancer is the most frequently diagnosed malignancy in women worldwide. Because of its great impact on society, a lot of research funding has been used to develop novel detection tools for aiding breast cancer diagnosis and prognosis. In this work, we demonstrated a simple, fast, and sensitive detection of circulating breast cancer biomarker CA15-3 with opto-fluidic ring resonator (OFRR) sensors. The OFRR sensor employs a thin-walled capillary with wall thickness less than 4 μm. The circular cross section of the capillary forms the optical ring resonator, in which the light circulates in the form of whispering gallery modes (WGMs). The capillary wall is thin enough that the evanescent field of the WGM extends into the capillary core and responds to refractive index changes in the capillary core or close to its interior surface. The WGM spectral position will change when the biomolecules bind to the surface, yielding quantitative and kinetic information about the biomolecule interaction. Here, the direct immunoassay method was employed for the detection of CA15-3 antigen without any signal amplification steps. The sensor performance in both PBS buffer and human serum were investigated, respectively. The experimental detection limit was 5 units/mL in PBS buffer and 30 units/mL for CA15-3 spiked in serum, both of which satisfied clinical diagnosis requirements. The potential use of the OFRR as the point-of-care device for breast cancer detection was tested by measuring the CA15-3 level in blood samples collected from stage IV breast cancer patients and the results were compared with standard clinical test.

13. VIEW OF EAST OPERATING GALLERY ALONG THE POSTMORTEM CELLS. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. VIEW OF EAST OPERATING GALLERY ALONG THE POST-MORTEM CELLS. A NUMBER OF MANIPULATOR ARMS COVERED WITH PLASTIC ARE ON THE LEFT WALL. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

8. MAIN INLET FROM FILTER GALLERY AND CANAL INTO HINDS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. MAIN INLET FROM FILTER GALLERY AND CANAL INTO HINDS PLANT. VIEW LOOKING DUE WEST OF HINDS COMPLEX IN BACKGROUND OF SAND FILTERS. - Hinds Pump Plant, East of Joshua Tree National Monument, 5 miles north of Route 10, Hayfield, Riverside County, CA

71. (Credit JTL) Pipe gallery looking south in basement underneath ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

71. (Credit JTL) Pipe gallery looking south in basement underneath 1910-11 and 1924 filter wing extensions. Note bottoms of converted New York horizontal pressure filters in right background. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

On the Problem of Filtration to an Imperfect Gallery in a Pressureless Bed

NASA Astrophysics Data System (ADS)

Bereslavskii, É. N.; Dudina, L. M.

2018-01-01

The problem of plane steady-state filtration in a pressureless bed to an imperfect gallery in the presence of evaporation from the flow free surface is considered. To study such type of flow, a mixed boundary-value problem of the theory of analytical functions is formulated and solved with application of the Polubarinova-Kochina method. Based on the model suggested, an algorithm for computing the discharge of the gallery and the ordinate of free surface emergence to the impermeable screen is developed. A detailed hydrodynamic analysis of the influence of all physical parameters of the model on the desired filtration characteristics is given.

An Old-Growth Definition for Western Hardwood Gallery Forests

Treesearch

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...

Beyond Art Waitressing: Meaningful Engagement in Interactive Art Galleries

ERIC Educational Resources Information Center

Kothe, Elsa Lenz

2012-01-01

The metaphor of "art waitressing" is a valuable tool for educators who seek guidance in enacting many of the new roles in museums, particularly the role of facilitator in an open-ended interactive gallery. Though this metaphor provides a valuable model for engaging visitors, the question quickly arises of how educators can go beyond "serving" an…

40. CONSTRUCTION OF GALLERY NO. 3, SHOWING INCLINED PLANE USED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

40. CONSTRUCTION OF GALLERY NO. 3, SHOWING INCLINED PLANE USED TO TRANSPORT MATERIALS, ALSO SPOIL FROM TUNNEL INTERIOR. POWDER HOUSE AND TOOL SHED VISIBLE TO RIGHT OF BASE INCLINE - Zion-Mount Carmel Highway, Tunnel, Two miles east of Zion Canyon Scenic Drive, Springdale, Washington County, UT

ASPRS Digital Imagery Guideline Image Gallery Discussion

NASA Technical Reports Server (NTRS)

Ryan, Robert

2002-01-01

The objectives of the image gallery are to 1) give users and providers a simple means of identifying appropriate imagery for a given application/feature extraction; and 2) define imagery sufficiently to be described in engineering and acquisition terms. This viewgraph presentation includes a discussion of edge response and aliasing for image processing, and a series of images illustrating the effects of signal to noise ratio (SNR) on images. Another series of images illustrates how images are affected by varying the ground sample distances (GSD).

76 FR 68101 - Safety Zone; Art Gallery Party St. Pete 2011 Fireworks Display, Tampa Bay, St. Petersburg, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-03

...-AA00 Safety Zone; Art Gallery Party St. Pete 2011 Fireworks Display, Tampa Bay, St. Petersburg, FL... temporary safety zone on the waters of Tampa Bay in the vicinity of Spa Beach in St. Petersburg, Florida during the Art Gallery Party St. Pete 2011 Fireworks Display on Friday, November 11, 2011. The safety...

45. MAIN MEETING ROOM COLUMNS. Ends of gallery columns identified ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

45. MAIN MEETING ROOM COLUMNS. Ends of gallery columns identified at the time of removal for transfer to the George School for re-erection. The stamp reads, 'REMOVED FROM 12th ST. MTG HSE PHILA 1972'. - Twelfth Street Meeting House, 20 South Twelfth Street, Philadelphia, Philadelphia County, PA

Efficient analysis of mode profiles in elliptical microcavity using dynamic-thermal electron-quantum medium FDTD method.

PubMed

Khoo, E H; Ahmed, I; Goh, R S M; Lee, K H; Hung, T G G; Li, E P

2013-03-11

The dynamic-thermal electron-quantum medium finite-difference time-domain (DTEQM-FDTD) method is used for efficient analysis of mode profile in elliptical microcavity. The resonance peak of the elliptical microcavity is studied by varying the length ratio. It is observed that at some length ratios, cavity mode is excited instead of whispering gallery mode. This depicts that mode profiles are length ratio dependent. Through the implementation of the DTEQM-FDTD on graphic processing unit (GPU), the simulation time is reduced by 300 times as compared to the CPU. This leads to an efficient optimization approach to design microcavity lasers for wide range of applications in photonic integrated circuits.

[Concordance among analysts from Latin-American laboratories for rice grain appearance determination using a gallery of digital images].

PubMed

Avila, Manuel; Graterol, Eduardo; Alezones, Jesús; Criollo, Beisy; Castillo, Dámaso; Kuri, Victoria; Oviedo, Norman; Moquete, Cesar; Romero, Marbella; Hanley, Zaida; Taylor, Margie

2012-06-01

The appearance of rice grain is a key aspect in quality determination. Mainly, this analysis is performed by expert analysts through visual observation; however, due to the subjective nature of the analysis, the results may vary among analysts. In order to evaluate the concordance between analysts from Latin-American rice quality laboratories for rice grain appearance through digital images, an inter-laboratory test was performed with ten analysts and images of 90 grains captured with a high resolution scanner. Rice grains were classified in four categories including translucent, chalky, white belly, and damaged grain. Data was categorized using statistic parameters like mode and its frequency, the relative concordance, and the reproducibility parameter kappa. Additionally, a referential image gallery of typical grain for each category was constructed based on mode frequency. Results showed a Kappa value of 0.49, corresponding to a moderate reproducibility, attributable to subjectivity in the visual analysis of grain images. These results reveal the need for standardize the evaluation criteria among analysts to improve the confidence of the determination of rice grain appearance.

Whispering gallery effect in relativistic optics

NASA Astrophysics Data System (ADS)

Abe, Y.; Law, K. F. F.; Korneev, Ph.; Fujioka, S.; Kojima, S.; Lee, S.-H.; Sakata, S.; Matsuo, K.; Oshima, A.; Morace, A.; Arikawa, Y.; Yogo, A.; Nakai, M.; Norimatsu, T.; d'Humières, E.; Santos, J. J.; Kondo, K.; Sunahara, A.; Gus'kov, S.; Tikhonchuk, V.

2018-03-01

relativistic laser pulse, confined in a cylindrical-like target, under specific conditions may perform multiple scattering along the internal target surface. This results in the confinement of the laser light, leading to a very efficient interaction. The demonstrated propagation of the laser pulse along the curved surface is just yet another example of the "whispering gallery" effect, although nonideal due to laser-plasma coupling. In the relativistic domain its important feature is a gradual intensity decrease, leading to changes in the interaction conditions. The proccess may pronounce itself in plenty of physical phenomena, including very efficient electron acceleration and generation of relativistic magnetized plasma structures.

The Habitable Zone Gallery 2.0: The Online Exoplanet System Visualization Suite

NASA Astrophysics Data System (ADS)

Chandler, C. O.; Kane, S. R.; Gelino, D. M.

2017-11-01

The Habitable Zone Gallery 2.0 provides new and improved visualization and data analysis tools to the exoplanet habitability community and beyond. Modules include interactive habitable zone plotting and downloadable 3D animations.

25. At 1050 Gallery, Block 55, view of gate control ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

25. At 1050 Gallery, Block 55, view of gate control and motor, looking west, (Westinghouse Gearmotor, ca. 1939, type CS induction motor, 440 volts, 43 rpm, 60 cycle). - Columbia Basin Project, Grand Coulee Dam & Franklin D. Roosevelt Lake, Across Columbia River, Southeast of Town of Grand Coulee, Grand Coulee, Grant County, WA

What is and what is not electromagnetically induced transparency in whispering-gallery microcavities.

PubMed

Peng, Bo; Özdemir, Sahin Kaya; Chen, Weijian; Nori, Franco; Yang, Lan

2014-10-24

There has been an increasing interest in all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting. Despite the differences in their underlying physics, both electromagnetically induced transparency and Autler-Townes splitting are quantified by a transparency window in the absorption or transmission spectrum, which often leads to a confusion about its origin. While the transparency window in electromagnetically induced transparency is a result of Fano interference among different transition pathways, in Autler-Townes splitting it is the result of strong field-driven interactions leading to the splitting of energy levels. Being able to tell objectively whether an observed transparency window is because of electromagnetically induced transparency or Autler-Townes splitting is crucial for applications and for clarifying the physics involved. Here we demonstrate the pathways leading to electromagnetically induced transparency, Fano resonances and Autler-Townes splitting in coupled whispering-gallery-mode resonators. Moreover, we report the application of the Akaike Information Criterion discerning between all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting and clarifying the transition between them.

Novel techniques for optical sensor using single core multi-layer structures for electric field detection

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Kamel, Mohamed A.

2017-05-01

This paper studies the effect of the electrostriction force on the single optical dielectric core coated with multi-layers based on whispering gallery mode (WGM). The sensing element is a dielectric core made of polymeric material coated with multi-layers having different dielectric and mechanical properties. The external electric field deforming the sensing element causing shifts in its WGM spectrum. The multi-layer structures will enhance the body and the pressure forces acting on the core of the sensing element. Due to the gradient on the dielectric permittivity; pressure forces at the interface between every two layers will be created. Also, the gradient on Young's modulus will affect the overall stiffness of the optical sensor. In turn the sensitivity of the optical sensor to the electric field will be increased when the materials of each layer selected properly. A mathematical model is used to test the effect for that multi-layer structures. Two layering techniques are considered to increase the sensor's sensitivity; (i) Pressure force enhancement technique; and (ii) Young's modulus reduction technique. In the first technique, Young's modulus is kept constant for all layers, while the dielectric permittivity is varying. In this technique the results will be affected by the value dielectric permittivity of the outer medium surrounding the cavity. If the medium's dielectric permittivity is greater than that of the cavity, then the ascending ordered layers of the cavity will yield the highest sensitivity (the core will have the smallest dielectric permittivity) to the applied electric field and vice versa. In the second technique, Young's modulus is varying along the layers, while the dielectric permittivity has a certain constant value per layer. On the other hand, the descending order will enhance the sensitivity in the second technique. Overall, results show the multi-layer cavity based on these techniques will enhance the sensitivity compared to the typical

Cylindrical optical resonators: fundamental properties and bio-sensing characteristics

NASA Astrophysics Data System (ADS)

Khozeymeh, Foroogh; Razaghi, Mohammad

2018-04-01

In this paper, detailed theoretical analysis of cylindrical resonators is demonstrated. As illustrated, these kinds of resonators can be used as optical bio-sensing devices. The proposed structure is analyzed using an analytical method based on Lam's approximation. This method is systematic and has simplified the tedious process of whispering-gallery mode (WGM) wavelength analysis in optical cylindrical biosensors. By this method, analysis of higher radial orders of high angular momentum WGMs has been possible. Using closed-form analytical equations, resonance wavelengths of higher radial and angular order WGMs of TE and TM polarization waves are calculated. It is shown that high angular momentum WGMs are more appropriate for bio-sensing applications. Some of the calculations are done using a numerical non-linear Newton method. A perfect match of 99.84% between the analytical and the numerical methods has been achieved. In order to verify the validity of the calculations, Meep simulations based on the finite difference time domain (FDTD) method are performed. In this case, a match of 96.70% between the analytical and FDTD results has been obtained. The analytical predictions are in good agreement with other experimental work (99.99% match). These results validate the proposed analytical modelling for the fast design of optical cylindrical biosensors. It is shown that by extending the proposed two-layer resonator structure analyzing scheme, it is possible to study a three-layer cylindrical resonator structure as well. Moreover, by this method, fast sensitivity optimization in cylindrical resonator-based biosensors has been possible. Sensitivity of the WGM resonances is analyzed as a function of the structural parameters of the cylindrical resonators. Based on the results, fourth radial order WGMs, with a resonator radius of 50 μm, display the most bulk refractive index sensitivity of 41.50 (nm/RIU).

From GUI to Gallery: A Study of Online Virtual Environments.

ERIC Educational Resources Information Center

Guynup, Stephen Lawrence

This paper began as an attempt to clarify and classify the development of Web3D environments from 1995 to the present. In that process, important facts came to light. A large proportion of these sites were virtual galleries and museums. Second, these same environments covered a wide array of architectural interpretations and represented some of…

5. INTERIOR VIEW OF LAUNDRY ROOM ON GALLERY LEVEL, NEAR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. INTERIOR VIEW OF LAUNDRY ROOM ON GALLERY LEVEL, NEAR SOUTHWEST CORNER OF BUILDING 149; WORKERS' UNIFORMS AND BEEF SHROUDS WERE LAUNDERED HERE; CLEAN BEEF SHROUDS WERE RETURNED TO DISASSEMBLY LINE ON LEVEL 4 THROUGH FUNNEL-SHAPED CHUTE AT LOWER LEFT - Rath Packing Company, Beef Killing Building, Sycamore Street between Elm & Eighteenth Streets, Waterloo, Black Hawk County, IA

The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna.

PubMed

Machado, Tâmara Dias Oliveira; Minuzzi-Souza, Thaís Tâmara Castro; Ferreira, Tauana de Sousa; Freire, Luciana Pereira; Timbó, Renata Velôzo; Vital, Tamires Emanuele; Nitz, Nadjar; Silva, Mariana Neiva; Santos, Alcinei de Souza; Sales, Nathyla Morgana Cunha; Obara, Marcos Takashi; Andrade, Andrey José de; Gurgel-Gonçalves, Rodrigo

2017-10-01

Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. 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. 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. 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. 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, Brazil.

Abundance and frugivory of the Toco toucan (Ramphastos toco) in a gallery forest in Brazil's southern Pantanal.

PubMed

Ragusa-Netto, J

2006-02-01

Unlike other toucan species, the Toco toucan (Ramphastos toco)--the largest Ramphastidae--usually inhabits dry semi-open areas. This conspicuous canopy frugivore uses a large home range that includes a variety of vegetation types, among which gallery forests are widely cited as important to this species. However, the factors relating to the occurrence of Toco toucans in such habitats are unclear. I studied the abundance of Toco toucans as well as the availability of fleshy fruit in a gallery forest in the southern Pantanal (sub-region of Miranda, Brazil), in order to assess the relationship between these parameters. Also, I examined toucan foraging activity to analyze its relationship with both toucan abundance and fruit availability. The presence of the Toco toucan was more common in the gallery forest from the middle to the end of the dry season and during the middle of the wet season. Toucans foraged for fleshy fruits, mainly Genipa americana, Ficus luschnatiana, and Cecropia pachystachya fruits, feeding mostly on G. americana (by far the favorite food resource) and F. luschnatiana fruits during the dry season, while C. pachystachya fruits were important in the wet season. Toco toucans foraged particularly heavily (> 80% of foraging activity) on G. americana fruits during the latter part of the dry season, when fleshy fruit availability declined sharply. Toco toucan abundance in the gallery forest was associated with the availability of the most commonly consumed fleshy fruits, and also with its foraging activity. This finding suggests that the Toco toucan moved to the gallery forest periodically in response to the availability of abundant food resources, especially the G. americana fruits widely available and exploited during the severely dry season. Therefore, these fruits potentially contribute to Toco toucan persistence in the South Pantanal during the harshest period of the year.

Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil).

PubMed

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.

The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

PubMed Central

Machado, Tâmara Dias Oliveira; Minuzzi-Souza, Thaís Tâmara Castro; Ferreira, Tauana de Sousa; Freire, Luciana Pereira; Timbó, Renata Velôzo; Vital, Tamires Emanuele; Nitz, Nadjar; Silva, Mariana Neiva; Santos, Alcinei de Souza; Sales, Nathyla Morgana Cunha; Obara, Marcos Takashi; de Andrade, Andrey José; Gurgel-Gonçalves, Rodrigo

2017-01-01

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, Brazil. PMID

From the galleries to the clinic: applying art museum lessons to patient care.

PubMed

Miller, Alexa; Grohe, Michelle; Khoshbin, Shahram; Katz, Joel T

2013-12-01

Increasingly, medical educators integrate art-viewing into curricular interventions that teach clinical observation-often with local art museum educators. How can cross-disciplinary collaborators explicitly connect the skills learned in the art museum with those used at the bedside? One approach is for educators to align their pedagogical approach using similar teaching methods in the separate contexts of the galleries and the clinic. We describe two linked pedagogical exercises--Visual Thinking Strategies (VTS) in the museum galleries and observation at the bedside--from "Training the Eye: Improving the Art of Physical Diagnosis," an elective museum-based course at Harvard Medical School. It is our opinion that while strategic interactions with the visual arts can improve skills, it is essential for students to apply them in a clinical context with faculty support-requiring educators across disciplines to learn from one another.

Visual Culture and Literacy Online: Image Galleries as Sites of Learning

ERIC Educational Resources Information Center

Carpenter, B. Stephen, II; Cifuentes, Lauren

2011-01-01

As new media emerge in the common culture, the authors recommend that art educators adopt those media to facilitate deep understanding of visual culture and literacy. They report here on applications of an online image gallery that helps users develop ways to interpret what they see and compose. Over the past few years the authors have…

Do isolated gallery-forest trees facilitate recruitment of forest seedlings and saplings in savannna?

NASA Astrophysics Data System (ADS)

Azihou, Akomian Fortuné; Glèlè Kakaï, Romain; Sinsin, Brice

2013-11-01

Facilitation is an ecological process that allows some species to establish in environments they can hardly afford in the absence of the process. This study investigated if the subcanopy of gallery-forest trees isolated in savanna is suitable for the early recruitment of forest woody species. We measured tree crown area as well as the density of seedlings and saplings of gallery-forest tree species beneath isolated trees and in the savanna matrix along 50 transects of 5-km long and 600 m wide located along four gallery forests. We then tested the nurse-plant effect and Janzen-Connell hypothesis beneath isolated trees. We also examined the relationships between the crown area and the density of seedlings and saplings. Among the eight identified tree species isolated in savanna, only Daniellia oliveri and Khaya senegalensis showed nurse-plant effect and promoted a significant, yet low early recruitment with a seedling-to-sapling survival of 0.044 and 0.578, respectively. The suitability of the subcanopy of isolated trees decreased with the recruitment progression and Janzen-Connell effects were absent. Seedlings had neutral association with the crown area of isolated trees which shifted to positive at the sapling stage. The species of the isolated tree and the crown area explained less than 20% of total variance, indicating that other predictive factors are important in explaining the nurse-plant effect observed in this study.

A&M. TAN607. Detail of control gallery for special services cubicle ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

A&M. TAN-607. Detail of control gallery for special services cubicle (hot cell) at "100 percent complete." Cover has been removed from cable channel at middle window. Date: January 24, 1995. INEEL negative No. 55-0140 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

Detecting single DNA molecule interactions with optical microcavities (Presentation Recording)

NASA Astrophysics Data System (ADS)

Vollmer, Frank

2015-09-01

circular optical path, similar to an acoustic wave guided along the wall of St. Paul's Cathedral. These so called whispering gallery modes (WGM) propagate with little loss, so that even a whisper can be heard on the other side of the gallery. In the optical case, the light beam can travel many thousand times around the inside of the microsphere before being scattered or absorbed, thereby making numerous interactions with an analyte molecule, bound to microsphere from surrounding sample solution. The most part of the light intensity, however, remains inside the microsphere, just below the reflecting glass surface, resulting in a relatively weak interaction between the light and the bound molecule. To enhance this interaction further, we attach tiny 42 nm x 12 nm gold nanorods to the glass surface. When passing a nanorod, the lightwave induces oscillations of conduction electrons, resulting in so called plasmon resonance. These nanorod plasmons greatly enhance the light intensity on the nanorod, so that the interaction of the light with a molecule attached to the nanorod is also enhanced[4-6]. This enhanced interaction results in an increase in sensitivity by more than a factor of one thousand, putting our experiments of single DNA molecule detection within reach. For the specific detection of nucleic acids, we attach single-stranded DNA to the nanorod and immerse our device in a liquid solution. When a matching, i.e. complementary DNA fragment binds from solution to the "bait" on the nanorod, the enhanced interaction with the light results in an observable shift of the WGM wavelength. Since light propagates in a WGM only for a very precise resonance wavelength or frequency, this shift can be detected with great accuracy[3]. On our current biosensor platform, we detect wavelength shifts with an accuracy of less than one femtometer, resulting in an extremely high sensitivity for biosensing, which we leverage for the specific detection of single 8 mer oligonucleotides as well

Lifelong Learning for People Aged 64+ within the Contemporary Art Gallery Context

ERIC Educational Resources Information Center

Goulding, Anna

2012-01-01

This paper reports the initial findings from Contemporary Visual Art and Identity Construction--Wellbeing Amongst Older People: a two-year research project that aims to understand how the lives of older people can be improved by examining their use of contemporary visual art in the art gallery and museum. It will focus on data relating to lifelong…

Artistic Sensibility in the Studio and Gallery Model: Revisiting Process and Product

ERIC Educational Resources Information Center

Thompson, Geoffrey

2009-01-01

This paper examines the cultivation of artistic sensibility and its impact on the art therapy process and product in a community mental health center. Artistic sensibility embodies the sense of self as an artist through the integration of artistic and aesthetic attributes of self and other. The formation of a gallery to exhibit patient art was…

Bringing Image and Language Together: A Workshop at the Lehman College Art Gallery.

ERIC Educational Resources Information Center

Wexler, Alice

2001-01-01

Discusses a ten day workshop for kindergarten and fourth grade students that centered around the art exhibit "Contemporary Chinese Art and the Literary Culture of China" held at the Lehman College Art Gallery (Bronx, New York). Explains that students created accordion books based on Xing Fei's "Red Book." (CMK)

A global reference model of Moho depths based on WGM2012

NASA Astrophysics Data System (ADS)

Zhou, D.; Li, C.

2017-12-01

The crust-mantle boundary (Moho discontinuity) represents the largest density contrast in the lithosphere, which can be detected by Bouguer gravity anomaly. We present our recent inversion of global Moho depths from World Gravity Map 2012. Because oceanic lithospheres increase in density as they cool, we perform thermal correction based on the plate cooling model. We adopt a temperature Tm=1300°C at the bottom of lithosphere. The plate thickness is tested by varying by 5 km from 90 to 140 km, and taken as 130 km that gives a best-fit crustal thickness constrained by seismic crustal thickness profiles. We obtain the residual Bouguer gravity anomalies by subtracting the thermal correction from WGM2012, and then estimate Moho depths based on the Parker-Oldenburg algorithm. Taking the global model Crust1.0 as a priori constraint, we adopt Moho density contrasts of 0.43 and 0.4 g/cm3 , and initial mean Moho depths of 37 and 20 km in the continental and oceanic domains, respectively. The number of iterations in the inversion is set to be 150, which is large enough to obtain an error lower than a pre-assigned convergence criterion. The estimated Moho depths range between 0 76 km, and are averaged at 36 and 15 km in continental and oceanic domain, respectively. Our results correlate very well with Crust1.0 with differences mostly within ±5.0 km. Compared to the low resolution of Crust1.0 in oceanic domain, our results have a much larger depth range reflecting diverse structures such as ridges, seamounts, volcanic chains and subduction zones. Base on this model, we find that young(<5 Ma) oceanic crust thicknesses show dependence on spreading rates: (1) From ultraslow (<4mm/yr) to slow (4 45mm/yr) spreading ridges, the thicknesses increase dramatically; (2)From slow to fast (45 95mm/yr) spreading ridges , the thickness decreases slightly; (3) For the super-fast ridges (>95mm/yr) we observe relatively thicker crust. Conductive cooling of lithosphere may constrain the

Novel design of electrical sensing interface for prosthetic limbs using optical micro cavities

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Kamel, Mohamed A.

2018-04-01

This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.

29. At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo Pumps, Buffalo, NY, driven by Allis Chalmers motors (size 3 HSO, head 230, 120 cpm, 1750, rpm, Impulse dia. 15) installed in the 1960s and used for water-cooling system for 230-kv cable; the cables have been removed and the pumps are not currently used. - Columbia Basin Project, Grand Coulee Dam & Franklin D. Roosevelt Lake, Across Columbia River, Southeast of Town of Grand Coulee, Grand Coulee, Grant County, WA

Characterization of azimuthal and longitudinal modes in rolled-up InGaAs/GaAs microtubes at telecom wavelengths.

PubMed

Zhong, Qiuhang; Tian, Zhaobing; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2013-08-12

We report on theoretical and experimental investigation of azimuthal and longitudinal modes in rolled-up microtubes at telecom wavelengths. These microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs bilayer. We apply planar waveguide method and a quasi-potential model to analyze the azimuthal and longitudinal modes in the microtubes near 1550 nm. Then we demonstrate these modes in transmission spectrum by evanescent light coupling. The experimental observations agree well with the calculated results. Surface-scattering-induced mode splitting is also observed in both transmission and reflection spectra at ~1600 nm. The mode splitting is in essence the non-degeneracy of clockwise and counter-clockwise whispering-gallery modes of the microtubes. This study is significant for understanding the physics of modes in microtubes and other microcavities with three-dimensional optical confinement, as well as for potential applications such as microtube-based photonic integrated devices and sensing purposes.

The Spiral Gallery: Non-Market Creativity and Belonging in an Australian Country Town

ERIC Educational Resources Information Center

Waitt, Gordon; Gibson, Chris

2013-01-01

This paper seeks to explore creative practice in an Australian country town, and in so doing, to unsettle market-orientated interpretations of creativity that privilege the urban. Instead of focusing on creative practice as a means to develop industries, we focus on how creativity is a means to establish a cooperative gallery space that helps to…

75 FR 15740 - Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of Investigation

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-30

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-72,907] Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of Investigation Pursuant to Section 221 of the Trade Act of 1974, as amended, an investigation was initiated in response to a petition filed on November 20, 2009...

The Art Gallery Test: A Preliminary Comparison between Traditional Neuropsychological and Ecological VR-Based Tests.

PubMed

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).

Victorian era esthetic and restorative dentistry: an advertising trade card gallery.

PubMed

Croll, Theodore P; Swanson, Ben Z

2006-01-01

A chief means of print advertising in the Victorian era was the "trade card." Innumerable products, companies, and services were highlighted on colorful chromolithographic trade cards, and these became desirable collectible objects which were pasted into scrapbooks and enjoyed by many families. Dentistry- and oral health-related subjects were often depicted on Victorian trade cards, and esthetic and restorative dentistry themes were featured. This review describes the history of advertising trade cards and offers a photographic gallery of dentistry-related cards of the era.

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications.

PubMed

Yamamoto, Yohei; Okada, Daichi; Kushida, Soh; Ngara, Zakarias Seba; Oki, Osamu

2017-06-02

This paper describes three methods of preparing fluorescent microspheres comprising π-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, π-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (µ-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, µ-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Morphology and ecology of Schizosthetus simulatrix (Acari, Mesotigmata) associated with galleries of bark beetles (Scolytidae)

Treesearch

Stanislav Klauz; Peter Masan; John C. Moser

2003-01-01

The deutonymphal stage and adults of Schizosthetus simulatrix Athias- Henriot, 1982 (Acari, Mesostigmata, Parasitidae), originally known from Canary Islands and Portugal, has been illustrated and described or redescribed, respectively. The subadults of S. simulatk have not previously been described. This very specialised subcorticolous species lives in galleries of...

Retention of external and internal markers by southern pine beetles (Coleoptera: Scolytidae) during gallery

Treesearch

Douglas J. Rhodes; Jane Leslie Hayes; Chris Steiner

1998-01-01

If retained, markers used in mark-release-recapture studies of bark beetle dispersal could provide valuable tools in the determination of post-dispersal fate. Retention of the internal marker rubidium (Rb) and of the external marker fluorescent powder during egg gallery construction, oviposition, and feeding were quantified at intervals from 0 to 96 hours by allowing...

A&M. TAN607. Interior view of operating gallery in hot shop. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

A&M. TAN-607. Interior view of operating gallery in hot shop. Shielded viewing windows are along right side of corridor. Cabinet on wheels at left of corridor is operating console for hot shop manipulators. When in use, it is stationed at window station and connected to appropriate control cables. note reserve bottles of zinc bromide above each station. Date: January 3, 1955. INEEL negative no. 55-0072 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

The Artist-Led Pedagogic Process in the Contemporary Art Gallery: Developing a Meaning Making Framework

ERIC Educational Resources Information Center

Pringle, Emily

2009-01-01

Drawing on recent research which examined how selected artist educators perceive themselves as arts practitioners and analysed how these constructions inform their pedagogy, this article proposes a framework of meaning making in the art gallery. Art practice is defined as a process of conceptual and experiential enquiry which embraces inspiration,…

Single-photon routing with whispering-gallery resonators

NASA Astrophysics Data System (ADS)

Huang, Jin-Song; Zhang, Jia-Hao; Wei, L. F.

2018-04-01

Quantum routing of single photons in a system with two waveguides coupled to two whispering-gallery resonators (WGRs) are investigated theoretically. Using a real-space full quantum theory, photonic scattering amplitudes along four ports of the waveguide network are analytically obtained. It is shown that, by adjusting the geometric and physical parameters of the two-WGR configuration, the quantum routing properties of single photons along the present waveguide network can be controlled effectively. The routing capability from input waveguide to another one can significantly exceed 0.5 near the resonance point of scattering spectra, which can be achieved with only one resonator. By properly designing the distance between two WGRs and the waveguide-WGR coupling strengths, the transfer rate between the waveguides can also reach certain sufficiently high values even in the non-resonance regime. Moreover, Fano-like resonances in the scattering spectra are designable. The proposed system may provide a potential application in controlling single-photon quantum routing.

High frequency of trypanosomatids in gallery forest bats of a Neotropical savanna.

PubMed

Lourenço, João Lucas M; Minuzzi-Souza, Thaís T C; Silva, Larissa R; Oliveira, Amanda C; Mendonça, Vagner J; Nitz, Nadjar; Aguiar, Ludmilla M S; Gurgel-Gonçalves, Rodrigo

2018-01-01

Bats are well-known hosts of trypanosomatids, though information about their role as reservoirs of these protozoans in the Brazilian savanna is poorly known. We aimed to analyze the occurrence of trypanosomatid species in bats occurring in remnants of gallery forests of Brasília, Federal District of Brazil. We sampled bats using mist nets in six sites, and we collected blood, wing fragments and oral swab samples from all captured individuals. Trypanosomatids were identified in the captured bats through sequencing of the SSUrRNA region and kDNA qPCR. We found no parasite in blood smears of 146 individuals of 14 species captured, but blood cultures were positive for nine bats. We detected trypanosomatids molecularly in 111 (76%) specimens of all bat species in the studied areas. Most of the infected bats had Leishmania-like DNA detected in blood and swab samples of the oral mucosa. We distinguished three species of Trypanosoma (Trypanosoma dionisii, T. rangeli and T. cruzi) in Carollia perspicillata. SSUrRNA PCR of oral samples is a non-invasive and practical method for identification of trypanosomatid species in bats. Our results support our belief that bats could be potential reservoirs for Trypanosoma and Leishmania-like species in the enzootic cycle of these parasites in gallery forests of the Brazilian Cerrado biome. Copyright © 2017 Elsevier B.V. All rights reserved.

Spin coating and plasma process for 2.5D and hybrid 3D micro-resonators on multilayer polymers

NASA Astrophysics Data System (ADS)

Bêche, B.; Gaviot, E.; Godet, C.; Zebda, A.; Potel, A.; Barbe, J.; Camberlein, L.; Vié, V.; Panizza, P.; Loas, G.; Hamel, C.; Zyss, J.; Huby, N.

2009-05-01

We have designed and realized three integrated photonic families of micro-resonators (MR) on multilayer organic materials. Such so-called 2.5D-MR and 3D-MR structures show off radius values ranging from 40 to 200μm. Both first and second families are especially designed on organic multilayer materials and shaped as ring- and disk-MR organics structures arranged upon (and coupled with) a pair of SU8-organic waveguides. The third family is related to hybrid 3D-MR structures composed of spherical glass-MR coupled to organic waveguides by a Langmuir-Blodgett lipid film about three nanometers in thickness. At first, polymer spin coating, surface plasma treatment and selective UV-lithography processes have been developed to realize 2.5D photonic micro-resonators. Secondly, we have designed and characterized photonic-quadripoles made of 3D-glass-MR arranged upon a pair of SU8 waveguides. Such structures are defined by a 4-ports or 4-waveguides coupled by the spherical glass-MR. We have achieved an evanescent photonic coupling between the 3D-MR and the 4-ports structure. Spectral resonances have been measured for 4-whispering gallery-modes (WGM) into such 3D-structures respectively characterized by a 0.97 nm free spectral range (FSR) and a high quality Q-factor up to 4.104.

Telerobotic Haptic Exploration in Art Galleries and Museums for Individuals with Visual Impairments.

PubMed

Park, Chung Hyuk; Ryu, Eun-Seok; Howard, Ayanna M

2015-01-01

This paper presents a haptic telepresence system that enables visually impaired users to explore locations with rich visual observation such as art galleries and museums by using a telepresence robot, a RGB-D sensor (color and depth camera), and a haptic interface. The recent improvement on RGB-D sensors has enabled real-time access to 3D spatial information in the form of point clouds. However, the real-time representation of this data in the form of tangible haptic experience has not been challenged enough, especially in the case of telepresence for individuals with visual impairments. Thus, the proposed system addresses the real-time haptic exploration of remote 3D information through video encoding and real-time 3D haptic rendering of the remote real-world environment. This paper investigates two scenarios in haptic telepresence, i.e., mobile navigation and object exploration in a remote environment. Participants with and without visual impairments participated in our experiments based on the two scenarios, and the system performance was validated. In conclusion, the proposed framework provides a new methodology of haptic telepresence for individuals with visual impairments by providing an enhanced interactive experience where they can remotely access public places (art galleries and museums) with the aid of haptic modality and robotic telepresence.

'Where Are We When We Think?' Space, Time and Emancipatory Education in Galleries

ERIC Educational Resources Information Center

Graham, Janna

2018-01-01

Adult education in art galleries sits on a fault line, at once an apparatus upholding the affirmative aspects of museum culture cultivated by global elites, a propellant in the whirring of an increasingly dislocated set of events on trendy and consumable political themes, and a site for 'allyship' and other kinds of radical and socially…

miRToolsGallery: a tag-based and rankable microRNA bioinformatics resources database portal

PubMed Central

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 PMID:29688355

Single-mode tunable laser emission in the single-exciton regime from colloidal nanocrystals

PubMed Central

Grivas, Christos; Li, Chunyong; Andreakou, Peristera; Wang, Pengfei; Ding, Ming; Brambilla, Gilberto; Manna, Liberato; Lagoudakis, Pavlos

2013-01-01

Whispering-gallery-mode resonators have been extensively used in conjunction with different materials for the development of a variety of photonic devices. Among the latter, hybrid structures, consisting of dielectric microspheres and colloidal core/shell semiconductor nanocrystals as gain media, have attracted interest for the development of microlasers and studies of cavity quantum electrodynamic effects. Here we demonstrate single-exciton, single-mode, spectrally tuned lasing from ensembles of optical antenna-designed, colloidal core/shell CdSe/CdS quantum rods deposited on silica microspheres. We obtain single-exciton emission by capitalizing on the band structure of the specific core/shell architecture that strongly localizes holes in the core, and the two-dimensional quantum confinement of electrons across the elongated shell. This creates a type-II conduction band alignment driven by coulombic repulsion that eliminates non-radiative multi-exciton Auger recombination processes, thereby inducing a large exciton–bi-exciton energy shift. Their ultra-low thresholds and single-mode, single-exciton emission make these hybrid lasers appealing for various applications, including quantum information processing. PMID:23974520

The potential of Lemna gibba L. and Lemna minor L. to remove Cu, Pb, Zn, and As in gallery water in a mining area in Keban, Turkey.

PubMed

Sasmaz, Merve; Arslan Topal, Emine Işıl; Obek, Erdal; Sasmaz, Ahmet

2015-11-01

This study was designed to investigate removal efficiencies of Cu, Pb, Zn, and As in gallery water in a mining area in Keban, Turkey by Lemna gibba L. and Lemna minor L. These plants were placed in the gallery water of Keban Pb-Zn ore deposits and adapted individually fed to the reactors. During the study period (8 days), the plant and water samples were collected daily and the temperature, pH, and electric conductivity of the gallery water were measured daily. The plants were washed, dried, and burned at 300 °C for 24 h in a drying oven. These ash and water samples were analyzed by ICP-MS to determine the amounts of Cu, Pb, Zn, and As. The Cu, Pb, Zn and As concentrations in the gallery water of the study area detected 67, 7.5, 7230, and 96 μg L(-1), respectively. According to the results, the obtained efficiencies in L. minor L. and L. gibba L. are: 87% at day 2 and 36% at day 3 for Cu; 1259% at day 2 and 1015% at day 2 for Pb; 628% at day 3 and 382% at day 3 for Zn; and 7070% at day 3 and 19,709% at day 2 for As, respectively. The present study revealed that both L. minor L. and L. gibba L. had very high potential to remove Cu, Pb, Zn, and As in gallery water contaminated by different ores. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Stories from History, Myth, and the Bible. Snite Museum of Art Gallery Guide. Parts 1-3.

ERIC Educational Resources Information Center

Matthias, Diana C. J.; Barrett, Jesse

This art education resource, designed for use in the Snite Museum of Art, may also be used with slides or reproductions. Black and white reproductions are included for each of the art works represented, along with title, artist, date, and media information. This three part gallery guide presents a brief synopsis of the stories narrated in the…

An Insurgent Curatorial Strategy: Using Dialogue and Collaboration to Create Meaning in Public Art Galleries and Museums

ERIC Educational Resources Information Center

Marsden, Scott

2018-01-01

My insurgent curatorial strategy incorporates theory around dialogue and is used to develop a participatory and collaborative process that gives voice to those who are marginalised and/or disfranchised and are suppressed by dominant social narratives. My strategy demonstrates how art galleries and museums can function as sites for community…

Changing the Rules: Making Space for Interactive Learning in the Galleries of the Detroit Institute of Arts

ERIC Educational Resources Information Center

Czajkowski, Jennifer Wild

2011-01-01

Three years after the Detroit Institute of Arts opened with all new, "visitor-centered" galleries, the museum's executive director of learning and interpretation shares the processes, successes, and lessons learned at an institution that embraced an array of hands-on learning models. The models are discussed as components of a…

Analysis of borehole expansion and gallery tests in anisotropic rock masses

USGS Publications Warehouse

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.

Agarose coated spherical micro resonator for humidity measurements.

PubMed

Mallik, Arun Kumar; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Farrell, Gerald; Semenova, Yuliya

2016-09-19

A new type of fiber optic relative humidity (RH) sensor based on an agarose coated silica microsphere resonator is proposed and experimentally demonstrated. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling using a tapered fiber with ~3.3 µm waist diameter. A change in the relative humidity of the surrounding the resonator air induces changes in the refractive index (RI) and thickness of the Agarose coating layer. These changes in turn lead to a spectral shift of the WGM resonances, which can be related to the RH value after a suitable calibration. Studies of the repeatability, long-term stability, measurement accuracy and temperature dependence of the proposed sensor are carried out. The RH sensitivity of the proposed sensor depends on the concentration of the agarose gel which determines the initial thickness of the deposited coating layer. Studies of the micro- resonators with coating layers fabricated from gels with three different Agarose concentrations of 0.5%, 1.125% and 2.25 wt./vol.% showed that an increase in the initial thickness of the coating material results in an increase in sensitivity but also leads to a decrease of quality factor (Q) of the micro resonator. The highest sensitivity achieved in our experiments was 518 pm/%RH in the RH range from 30% to 70%. The proposed sensor offers the advantages of a very compact form factor, low hysteresis, good repeatability, and low cross sensitivity to temperature.

Social Phenomenological Analysis as a Research Method in Art Education: Developing an Empirical Model for Understanding Gallery Talks

ERIC Educational Resources Information Center

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…

Lesbian identity and the politics of representation in Betty Parsons's gallery.

PubMed

Gibson, A

1994-01-01

Although Betty Parsons had been unusually open about her love relationships with women in the twenties and thirties, she later became reticent, retiring to the closet. Her increased discretion after World War II, during the Cold War, coincided with her rise as the art dealer most prominently associated with the international emergence of Abstract Expressionism. Parsons incurred the objections of her Abstract Expressionists, however, by showing artists who included both abstraction and naturalism in their work, such as Sonia Sekula, Forrest Bess, and Hedda Sterne. This article examines her definition of abstraction as difference through her friend Theodoros Stamos's notion of camp and helps to explain her admiration of Barnett Newman despite her refusal to devote her gallery exclusively to his narrower version of significant abstraction.

Staging scientific controversies: a gallery test on science museums' interactivity.

PubMed

Yaneva, Albena; Rabesandratana, Tania Mara; Greiner, Birgit

2009-01-01

The "transfer" model in science communication has been addressed critically from different perspectives, while the advantages of the interactive model have been continuously praised. Yet, little is done to account for the specific role of the interactive model in communicating "unfinished science." The traditional interactive methods in museums are not sufficient to keep pace with rapid scientific developments. Interactive exchanges between laypeople and experts are thought mainly through the lens of a dialogue that is facilitated and framed by the traditional "conference room" architecture. Drawing on the results of a small-scale experiment in a gallery space, we argue for the need for a new "architecture of interaction" in museum settings based on art installation and simulation techniques, which will enhance the communication potentials of science museums and will provide conditions for a fruitful even-handed exchange of expert and lay knowledge.

Thermal Properties of Whispering Gallery Mode Resonators

DTIC Science & Technology

2014-12-22

in a vacuum chamber, to lower the noise floor and increase the SNR. To study the frequency response of the IR detector , we varied the modulation...performance at a fixed IR modulation (chopping) frequency. Finally, we estimated the noise equivalent power (NEP) of our IR detector . Note that the...the thennal relaxation time of the resonator to estimate the response time of the resonator based infrared (IR) detector . We found that, depending on

Crafting glass vessels: current research on the ancient glass collections in the Freer Gallery of Art, Washington, D.C.

NASA Astrophysics Data System (ADS)

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.

Adult Education for Social and Environmental Change in Contemporary Public Art Galleries and Museums in Canada, Scotland and England

ERIC Educational Resources Information Center

Clover, Darlene E.

2015-01-01

Historically, pubic art galleries and museums have a well-deserved reputation for elitism, colonialism and exclusion and they are, therefore, frequently omitted from the discourse of adult education. However, the escalating social, cultural and ecological problems of this new century have placed pressure on these public institutions to change and…

A Survey on the Influence of Titles on the Visitor's Interpretation and Learning in Art Galleries: An Iranian Context

ERIC Educational Resources Information Center

Samanian, Kouros; Nedaeifar, Hoda; Karimi, Ma'soumeh

2016-01-01

As previous studies suggest, titles of works of art have generally proven to be influential elements in reading and interpretation of the artworks. In the exhibition context, titles can be considered as a physical component of the museum or art gallery's space. According to the relatively new approaches, learning, being a subcategory of…

Neuroelectric brain imaging during a real visit of a fine arts gallery: a neuroaesthetic study of XVII century Dutch painters.

PubMed

Babiloni, F; Cherubino, P; Graziani, I; Trettel, A; Infarinato, F; Picconi, D; Borghini, G; Maglione, A G; Mattia, D; Vecchiato, G

2013-01-01

Neuroaesthetic is a scientific discipline founded more than a decade ago and it refers to the study of the neural bases of beauty perception in art. The aim of this paper is to investigate the neuroelectrical correlates of brain activity of the observation of real paintings showed in a national fine arts gallery (Scuderie del Quirinale) in Rome, Italy. In fact, the present study was designed to examine how motivational factors as indexed by EEG asymmetry over the prefrontal cortex (relative activity of the left and right hemispheres) could be related to the experience of viewing a series of figurative paintings. The fine arts gallery was visited by a group of 25 subjects during an exhibition of the XVII century Dutch painters. Results suggested a strict correlation of the estimated EEG asymmetry with the verbal pleasantness scores reported by the subjects (p<0,05) and an inverse correlation of the perceived pleasantness with the observed painting's surface dimensions (p<0,002).

THE BOSS EMISSION-LINE LENS SURVEY. IV. SMOOTH LENS MODELS FOR THE BELLS GALLERY SAMPLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, Yiping; Bolton, Adam S.; Montero-Dorta, Antonio D.

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 thoroughmore » 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.« less

Design and Development of Nanostructured Surfaces for Enhanced Optical Sensing

NASA Astrophysics Data System (ADS)

Santiago Cordoba, Miguel A.

At smaller size regimes, materials' physicochemical properties change with respect to bulk analogs. In the case of metal nanoparticles like gold or silver, specific wavelengths of light can induce a coherent oscillation of their conduction electrons, generating an optical field confined to the nanoparticle surface. This phenomenon is termed surface plasmon, and has been used as an enhancing mechanism in optical sensing, allowing the detection of foreign materials at small concentrations. The goal of this dissertation is to develop nanostructured materials relying on surface plasmons that can be combined with different optical sensing platforms in order to enhance current detection limits. Initially, we focus on the development of surfactant free, stimuli responsive nanoparticle thin films, which undergo an active release when exposed to a stimulus such as a change in pH. These nanoparticle thin films provide faster analyte particle transport and direct electronic coupling with the analyte molecule, all without attenuating the evanescent wave from the optical transducer to the particle. These stimuli responsive nanostructured substrates are tested within a surface enhanced Raman platform for the detection of biomolecular probes at sub-nanomolar concentrations and microL sample sizes. Furthermore, the developed nanosubstrates can be patterned, providing a versatile nanoparticle thin film for multiplexing analysis, offering a substantial advantage over conventional surface based nanoparticle detection methods. Our results encouraged further optimization of light-matter interactions in optical detection platforms. It is for that reason that this dissertation evolves towards confined optical systems. Particularly, whispering gallery microcavities confine electromagnetic waves - at high volumes - at the boundary of a dielectric resonator. In this dissertation, we examined the sensitivity of whispering gallery modes combining optical microcavities with plasmonic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zubov, F. I.; Kryzhanovskaya, N. V.; Moiseev, E. I.

The spectral, threshold, and power characteristics of a microdisk laser 31 μm in diameter with an active region based on InAs/InGaAs quantum dots, operating in the continuous-wave (cw) mode at room temperature are studied. The minimum threshold current density is 0.58 kA/cm{sup 2}, the subthreshold linewidth of the whispering-gallery mode is 50 pm at a wavelength lying in the range of 1.26–1.27 μm. The total power emitted into free space reaches ~0.1 mW in the cw mode, whereas the radiation power of the whispering-gallery modes is ~2.8%.

Passion Trumps Pay: A Study of the Future Skills Requirements of Information Professionals in Galleries, Libraries, Archives and Museums in Australia

ERIC Educational Resources Information Center

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…

Identification of Natural Oscillation Modes for Purposes of Seismic Assessment and Monitoring of HPP Dams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuz’menko, A. P., E-mail: apkuzm@gmail.com; Saburov, S. V., E-mail: saburov58@yandex.ru

2016-07-15

The paper puts forward a method for processing data from detailed seismic assessments of HPP dams (dynamic tests). A detailed assessment (hundreds of observation points in dam galleries) is performed with consideration of operating dam equipment and the microseismic noise. It is shown that dynamic oscillation characteristics (natural oscillation frequencies and modes in the main dam axes, the velocities of propagation of elastic waves with given polarization, and so on.) can be determined with sufficient accuracy by using complex transfer functions and pulse characteristics. Monitoring data is processed using data from a detailed assessment, taking account of identified natural oscillationmore » modes and determined ranges of natural frequencies. The spectra of characteristic frequencies thus obtained are used to choose substitution models and estimate the elastic characteristics of the “dam – rock bed” construction system, viz., the modulus of elasticity (the Young modulus), the Poisson ratio, the dam section stiffness with respect to shear, tension and compression and the elastic characteristics of the rock foundation.« less

Whispering gallery states of neutrons and anti-hydrogen atoms and their applications to fundamental and surface physics

NASA Astrophysics Data System (ADS)

Nesvizhevsky, Valery

2013-03-01

The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It is intensively used and explored due to its numerous crucial applications. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for neutrons and (anti)atoms. For (anti)matter waves, it includes a new feature: a massive particle is settled in quantum states, with parameters depending on its mass. In this talk, we present the first observation of the quantum whispering-gallery effect for matter particles (cold neutrons) 1-2. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to recently discovered gravitational quantum states of neutrons3. These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a quantum state. Deeply bound long-living states are weakly sensitive to surface potential; highly excited short-living states are very sensitive to the wall nuclear potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects. Analogous phenomena could be measured with atoms and anti-atoms 4-5.

Distribution, diversity, mesonotal morphology, gallery architecture, and queen physogastry of the termite genus Calcaritermes (Isoptera, Kalotermitidae)

PubMed Central

Scheffrahn, Rudolf H.

2011-01-01

Abstract An updated New World distribution of the genus Calcaritermes is given along with photographs and a key to the New World species outside Mexico. Calcaritermes recessifrons is found to be a junior synonym of Calcaritermes nigriceps. Except for Calcaritermes temnocephalus, pseudergates of the other seven studied Calcaritermes species possess a mesonotal rasp. The rasps suggest a role in propagation of microbes on gallery surfaces and microbial infusion below the wood surface. Calcaritermes temoncephalus is shown to have an unusually large physogastric queens for a kalotermitid and several species produce large eggs. PMID:22287890

Brillouin Light Scattering by Magnetic Quasivortices in Cavity Optomagnonics

NASA Astrophysics Data System (ADS)

Osada, A.; Gloppe, A.; Hisatomi, R.; Noguchi, A.; Yamazaki, R.; Nomura, M.; Nakamura, Y.; Usami, K.

2018-03-01

A ferromagnetic sphere can support optical vortices in the form of whispering gallery modes and magnetic quasivortices in the form of magnetostatic modes with nontrivial spin textures. These vortices can be characterized by their orbital angular momenta. We experimentally investigate Brillouin scattering of photons in the whispering gallery modes by magnons in the magnetostatic modes, zeroing in on the exchange of the orbital angular momenta between the optical vortices and magnetic quasivortices. We find that the conservation of the orbital angular momentum results in different nonreciprocal behavior in the Brillouin light scattering. New avenues for chiral optics and optospintronics can be opened up by taking the orbital angular momenta as a new degree of freedom for cavity optomagnonics.

Enhanced Raman scattering of single nanoparticles in a high-Q whispering-gallery microresonator

NASA Astrophysics Data System (ADS)

Liu, Rui-Shan; Jin, Wei-Liang; Yu, Xiao-Chong; Liu, Yong-Chun; Xiao, Yun-Feng

2015-04-01

We study Raman scattering of single nanoparticles coupled to a high-Q whispering-gallery microresonator. It is found that cavity resonances greatly enhance the Raman signal, and the enhancement factor is as high as 108. Unlike the noncavity case, the signal power exhibits a nonmonotonic dependence on particle size, and it reaches the maximum when the Rayleigh scattering loss and the cavity intrinsic loss are comparable. We further analyze how the Raman signal intensity is influenced by different parameters including cavity quality factors and taper-cavity coupling strength. The detection limit of observing single-nanoparticle Raman signal is discussed finally. As a potential application, this mechanism may provide an alternative way to detect specific biological targets without the need of precovered biorecognitions.

3-D density imaging with muon flux measurements from underground galleries

NASA Astrophysics Data System (ADS)

Lesparre, N.; Cabrera, J.; Marteau, J.

2017-03-01

Atmospheric muon flux measurements provide information on subsurface density distribution. In this study, muon flux was measured underground, in the Tournemire experimental platform (France). The objective was to image the medium between the galleries and the surface and evaluate the feasibility to detect the presence of discontinuities, for example, produced by secondary subvertical faults or by karstic networks. Measurements were performed from three different sites with a partial overlap of muon trajectories, offering the possibility to seek density variations at different depths. The conversion of the measured muon flux to average density values showed global variations further analysed through a 3-D nonlinear inversion procedure. Main results are the presence of a very low density region at the level of the upper aquifer, compatible with the presence of a karstic network hosting local cavities, and the absence of secondary faults. We discuss the validity of the present results and propose different strategies to improve the accuracy of such measurements and analysis.

How to use The National Gallery as a cross curricular approach to weather and climate studies at primary level.

NASA Astrophysics Data System (ADS)

Hansen, P. J. K.

2009-09-01

How to use The National Gallery as a cross curricular approach to weather and climate studies at primary level. Pål J. Kirkeby Hansen Faculty of Education and International Studies, Oslo University College (PalKirkeby.Hansen@lui.hio.no) Weather and climate are topics in natural science and geography in primary and secondary education in most countries. The pupils are often doing own weather observations and measurements and are presenting the results oral, by posters or with digital aids. They also use the Internet with all its relevant resources in their studies to develop vocabulary, practical and conceptual knowledge. Knowledge about weather and climate is parts of liberal education and could be projected to other topics in science and to topics in other subjects, for instance: history, social geography, literature and arts. This article reports from a case study in grade 3 classes (age 9 year) during their Weather Week. Their science teacher was, quite untypical, also educated in art history. She arranged a visited to The National Gallery with the double agenda: 1. To introduce the pupils to Norwegian canon paintings from the national romantic period, our so-called "golden age”. 2. To look for and discuss weather elements in this paintings. For one hour the museum curator guided the pupils around the water cycle by using the paintings. While the pupils' own observations of weather, clouds and wind and measurements of temperature and precipitation during the Weather Week only are point checks, the guided tour in The National Gallery gave literally "the whole picture” of the Norwegian weather and climate and of the water cycle. During the tour, the curator constantly invited the pupils to tell about and discuss what weather and water elements they were looking at when standing in front of a painting. The pupils were responsive and interested all the time. Back at school, they demonstrated that they had learned much about both weather elements, the water

Voice over: Audio-visual congruency and content recall in the gallery setting

PubMed Central

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

Voice over: Audio-visual congruency and content recall in the gallery setting.

PubMed

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.

The structure of gallery networks in the nests of termite Cubitermes spp. revealed by X-ray tomography

NASA Astrophysics Data System (ADS)

Perna, Andrea; Jost, Christian; Couturier, Etienne; Valverde, Sergi; Douady, Stéphane; Theraulaz, Guy

2008-09-01

Recent studies have introduced computer tomography (CT) as a tool for the visualisation and characterisation of insect architectures. Here, we use CT to map the three-dimensional networks of galleries inside Cubitermes nests in order to analyse them with tools from graph theory. The structure of these networks indicates that connections inside the nest are rearranged during the whole nest life. The functional analysis reveals that the final network topology represents an excellent compromise between efficient connectivity inside the nest and defence against attacking predators. We further discuss and illustrate the usefulness of CT to disentangle environmental and specific influences on nest architecture.

High Efficiency Coupling of Optical Fibres with SU8 Micro-droplet Using Laser Welding Process

NASA Astrophysics Data System (ADS)

Yardi, Seema; Gupta, Ankur; Sundriyal, Poonam; Bhatt, Geeta; Kant, Rishi; Boolchandani, D.; Bhattacharya, Shantanu

2016-09-01

Apart from micro- structure fabrication, ablation, lithography etc., lasers find a lot of utility in various areas like precision joining, device fabrication, local heat delivery for surface texturing and local change of microstructure fabrication of standalone optical micro-devices (like microspheres, micro-prisms, micro-scale ring resonators, optical switches etc). There is a wide utility of such systems in chemical/ biochemical diagnostics and also communications where the standalone optical devices exist at a commercial scale but chip based devices with printed optics are necessary due to coupling issues between printed structures and external optics. This paper demonstrates a novel fabrication strategy used to join standalone optical fibres to microchip based printed optics using a simple SU8 drop. The fabrication process is deployed for fiber to fiber optical coupling and coupling between fiber and printed SU-8 waveguides. A CO2 laser is used to locally heat the coupling made up of SU8 material. Optimization of various dimensional parameters using design of experiments (DOE) on the bonded assembly has been performed as a function of laser power, speed, cycle control, spot size so on so forth. Exclusive optical [RF] modelling has been performed to estimate the transmissibility of the optical fibers bonded to each other on a surface with SU8. Our studies indicate the formation of a Whispering gallery mode (WGM) across the micro-droplet leading to high transmissibility of the signal. Through this work we have thus been able to develop a method of fabrication for optical coupling of standalone fibers or coupling of on-chip optics with off-chip illumination/detection.

Impact of short-term intake of red wine and grape polyphenol extract on the human metabolome.

PubMed

Jacobs, Doris M; Fuhrmann, Jens C; van Dorsten, Ferdinand A; Rein, Dietrich; Peters, Sonja; van Velzen, Ewoud J J; Hollebrands, Boudewijn; Draijer, Richard; van Duynhoven, John; Garczarek, Ursula

2012-03-28

Red wine and grape polyphenols are considered to promote cardiovascular health and are involved in multiple biological functions. Their overall impact on the human metabolome is not known. Therefore, exogenous and endogenous metabolic effects were determined in fasting plasma and 24 h urine from healthy male adults consuming a mix of red wine and grape juice extracts (WGM) for 4 days in a placebo-controlled, crossover study. Syringic acid, 3-hydroxyhippuric acid, pyrogallol, 3-hydroxyphenylacetic acid, and 3-hydroxyphenylpropionic acid were confirmed as the strongest urinary markers of WGM intake. Overall, WGM had a mild impact on the endogenous metabolism. Most noticeable were changes in several amino acids deriving from tyrosine and tryptophan. Reductions in the microbial metabolites p-cresol sulfate and 3-indoxylsulfuric acid and increases in indole-3-lactic acid and nicotinic acid were observed in urine. In plasma, tyrosine was reduced. The results suggest that short-term intake of WGM altered microbial protein fermentation and/or amino acid metabolism.

Determination of the in vivo prebiotic potential of a maize-based whole grain breakfast cereal: a human feeding study.

PubMed

Carvalho-Wells, Andrew L; Helmolz, Kathrin; Nodet, Cecelia; Molzer, Christine; Leonard, Clare; McKevith, Brigid; Thielecke, Frank; Jackson, Kim G; Tuohy, Kieran M

2010-11-01

Epidemiological studies have shown an inverse relationship between risk of CVD and intake of whole grain (WG)-rich food. Regular consumption of breakfast cereals can provide not only an increase in dietary WG but also improvements to cardiovascular health. Various mechanisms have been proposed, including prebiotic modulation of the colonic microbiota. In the present study, the prebiotic activity of a maize-derived WG cereal (WGM) was evaluated in a double-blind, placebo-controlled human feeding study (n 32). For a period of 21 d, healthy men and women, mean age 32 (sd 8) years and BMI 23·3 (sd 0·58) kg/m2, consumed either 48 g/d WG cereal (WGM) or 48 g placebo cereal (non-whole grain (NWG)) in a crossover fashion. Faecal samples were collected at five points during the study on days 0, 21, 42, 63 and 84 (representing at baseline, after both treatments and both wash-out periods). Faecal bacteriology was assessed using fluorescence in situ hybridisation with 16S rRNA oligonucleotide probes specific for Bacteroides spp., Bifidobacterium spp., Clostridium histolyticum/perfringens subgroup, Lactobacillus-Enterococcus subgroup and total bacteria. After 21 d consumption of WGM, mean group levels of faecal bifidobacteria increased significantly compared with the control cereal (P = 0·001). After a 3-week wash-out period, bifidobacterial levels returned to pre-intervention levels. No statistically significant changes were observed in serum lipids, glucose or measures of faecal output. In conclusion, this WG maize-enriched breakfast cereal mediated a bifidogenic modulation of the gut microbiota, indicating a possible prebiotic mode of action.

NASA Tech Briefs, November 2008

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: Digital Phase Meter for a Laser Heterodyne Interferometer; Vision System Measures Motions of Robot and External Objects; Advanced Precipitation Radar Antenna to Measure Rainfall From Space; Wide-Band Radar for Measuring Thickness of Sea Ice; Vertical Isolation for Photodiodes in CMOS Imagers; Wide-Band Microwave Receivers Using Photonic Processing; L-Band Transmit/Receive Module for Phase-Stable Array Antennas; Microwave Power Combiner/Switch Utilizing a Faraday Rotator; Compact Low-Loss Planar Magic-T; Using Pipelined XNOR Logic to Reduce SEU Risks in State Machines; Quasi-Optical Transmission Line for 94-GHz Radar; Next Generation Flight Controller Trainer System; Converting from DDOR SASF to APF; Converting from CVF to AAF; Documenting AUTOGEN and APGEN Model Files; Sequence History Update Tool; Extraction and Analysis of Display Data; MRO DKF Post-Processing Tool; Rig Diagnostic Tools; MRO Sequence Checking Tool; Science Activity Planner for the MER Mission; UAVSAR Flight-Planning System; Templates for Deposition of Microscopic Pointed Structures; Adjustable Membrane Mirrors Incorporating G-Elastomers; Hall-Effect Thruster Utilizing Bismuth as Propellant; High-Temperature Crystal-Growth Cartridge Tubes Made by VPS; Quench Crucibles Reinforced with Metal; Deep-Sea Hydrothermal-Vent Sampler; Mars Rocket Propulsion System; Two-Stage Passive Vibration Isolator; Improved Thermal Design of a Compression Mold; Enhanced Pseudo-Waypoint Guidance for Spacecraft Maneuvers; Altimetry Using GPS-Reflection/Occultation Interferometry; Thermally Driven Josephson Effect; Perturbation Effects on a Supercritical C7H16/N2 Mixing Layer; Gold Nanoparticle Labels Amplify Ellipsometric Signals; Phase Matching of Diverse Modes in a WGM Resonator; WGM Resonators for Terahertz-to-Optical Frequency Conversion; Determining Concentration of Nanoparticles from Ellipsometry; Microwave-to-Optical Conversion in WGM Resonators; Four-Pass Coupler for Laser

A Resonator for Low-Threshold Frequency Conversion

NASA Technical Reports Server (NTRS)

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

2004-01-01

A proposed toroidal or disklike dielectric optical resonator (dielectric optical cavity) would be made of an optically nonlinear material and would be optimized for use in parametric frequency conversion by imposition of a spatially periodic permanent electric polarization. The poling (see figure) would suppress dispersions caused by both the material and the geometry of the optical cavity, thereby effecting quasi-matching of the phases of high-resonance-quality (high-Q) whispering-gallery electromagnetic modes. The quasi-phase-matching of the modes would serve to maximize the interactions among them. Such a resonator might be a prototype of a family of compact, efficient nonlinear devices for operation over a broad range of optical wavelengths. A little background information is prerequisite to a meaningful description of this proposal: (1) Described in several prior NASA Tech Briefs articles, the whispering-gallery modes in a component of spheroidal, disklike, or toroidal shape are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. (2) For the sake of completeness, it must be stated that even though optical resonators of the type considered here are solid dielectric objects and light is confined within them by total internal reflection at dielectric interfaces without need for mirrors, such components are sometimes traditionally called cavities because their effects upon the light propagating within them are similar to those of true cavities bounded by mirrors. (3) For a given set of electromagnetic modes interacting with each other in an optically nonlinear material (e.g., modes associated with the frequencies involved in a frequency-conversion scheme), the threshold power for oscillation depends on the mode volumes and the mode-overlap integral. (4) Whispering-gallery modes are attractive in nonlinear optics because they maximize the effects of

Cleaning procedure for improved photothermal background of toroidal optical microresonators

NASA Astrophysics Data System (ADS)

Horak, Erik H.; Knapper, Kassandra A.; Heylman, Kevin D.; Goldsmith, Randall H.

2016-09-01

High Q-factors and small mode volumes have made toroidal optical microresonators exquisite sensors to small shifts in the effective refractive index of the WGM modes. Eliminating contaminants and improving quality factors is key for many different sensing techniques, and is particularly important for photothermal imaging as contaminants add photothermal background obscuring objects of interest. Several different cleaning procedures including wet- and dry-chemical procedures are tested for their effect on Q-factors and photothermal background. RCA cleaning was shown to be successful in contrast to previously described acid cleaning procedures, most likely due to the different surface reactivity of the acid reagents used. UV-ozone cleaning was shown to be vastly superior to O2 plasma cleaning procedures, significantly reducing the photothermal background of the resonator.

NASA Tech Briefs, October 2008

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: Control Architecture for Robotic Agent Command and Sensing; Algorithm for Wavefront Sensing Using an Extended Scene; CO2 Sensors Based on Nanocrystalline SnO2 Doped with CuO; Improved Airborne System for Sensing Wildfires; VHF Wide-Band, Dual-Polarization Microstrip-Patch Antenna; Onboard Data Processor for Change-Detection Radar Imaging; Using LDPC Code Constraints to Aid Recovery of Symbol Timing; System for Measuring Flexing of a Large Spaceborne Structure; Integrated Formation Optical Communication and Estimation System; Making Superconducting Welds between Superconducting Wires; Method for Thermal Spraying of Coatings Using Resonant-Pulsed Combustion; Coating Reduces Ice Adhesion; Hybrid Multifoil Aerogel Thermal Insulation; SHINE Virtual Machine Model for In-flight Updates of Critical Mission Software; Mars Image Collection Mosaic Builder; Providing Internet Access to High-Resolution Mars Images; Providing Internet Access to High-Resolution Lunar Images; Expressions Module for the Satellite Orbit Analysis Program Virtual Satellite; Small-Body Extensions for the Satellite Orbit Analysis Program (SOAP); Scripting Module for the Satellite Orbit Analysis Program (SOAP); XML-Based SHINE Knowledge Base Interchange Language; Core Technical Capability Laboratory Management System; MRO SOW Daily Script; Tool for Inspecting Alignment of Twinaxial Connectors; An ATP System for Deep-Space Optical Communication; Polar Traverse Rover Instrument; Expert System Control of Plant Growth in an Enclosed Space; Detecting Phycocyanin-Pigmented Microbes in Reflected Light; DMAC and NMP as Electrolyte Additives for Li-Ion Cells; Mass Spectrometer Containing Multiple Fixed Collectors; Waveguide Harmonic Generator for the SIM; Whispering Gallery Mode Resonator with Orthogonally Reconfigurable Filter Function; Stable Calibration of Raman Lidar Water-Vapor Measurements; Bimaterial Thermal Compensators for WGM Resonators; Root Source Analysis/ValuStream[Trade Mark

Self-injection locked blue laser

NASA Astrophysics Data System (ADS)

Donvalkar, Prathamesh S.; Savchenkov, Anatoliy; Matsko, Andrey

2018-04-01

We demonstrate a 446.5 nm GaN semiconductor laser with sub-MHz linewidth. The linewidth reduction is achieved by locking the laser to a magnesium fluoride whispering gallery mode resonator characterized with 109 quality factor. Self-injection locking ensures single longitudinal mode operation of the laser.

Chaos-assisted broadband momentum transformation in optical microresonators

NASA Astrophysics Data System (ADS)

Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

2017-10-01

The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks.

Whole-genome typing and characterization of blaVIM19-harbouring ST383 Klebsiella pneumoniae by PFGE, whole-genome mapping and WGS.

PubMed

Sabirova, Julia S; Xavier, Basil Britto; Coppens, Jasmine; Zarkotou, Olympia; Lammens, Christine; Janssens, Lore; Burggrave, Ronald; Wagner, Trevor; Goossens, Herman; Malhotra-Kumar, Surbhi

2016-06-01

We utilized whole-genome mapping (WGM) and WGS to characterize 12 clinical carbapenem-resistant Klebsiella pneumoniae strains (TGH1-TGH12). All strains were screened for carbapenemase genes by PCR, and typed by MLST, PFGE (XbaI) and WGM (AflII) (OpGen, USA). WGS (Illumina) was performed on TGH8 and TGH10. Reads were de novo assembled and annotated [SPAdes, Rapid Annotation Subsystem Technology (RAST)]. Contigs were aligned directly, and after in silico AflII restriction, with corresponding WGMs (MapSolver, OpGen; BioNumerics, Applied Maths). All 12 strains were ST383. Of the 12 strains, 11 were carbapenem resistant, 7 harboured blaKPC-2 and 11 harboured blaVIM-19. Varying the parameters for assigning WGM clusters showed that these were comparable to STs and to the eight PFGE types or subtypes (difference of three or more bands). A 95% similarity coefficient assigned all 12 WGMs to a single cluster, whereas a 99% similarity coefficient (or ≥10 unmatched-fragment difference) assigned the 12 WGMs to eight (sub)clusters. Based on a difference of three or more bands between PFGE profiles, the Simpson's diversity indices (SDIs) of WGM (0.94, Jackknife pseudo-values CI: 0.883-0.996) and PFGE (0.93, Jackknife pseudo-values CI: 0.828-1.000) were similar (P = 0.649). However, the discriminatory power of WGM was significantly higher (SDI: 0.94, Jackknife pseudo-values CI: 0.883-0.996) than that of PFGE profiles typed on a difference of seven or more bands (SDI: 0.53, Jackknife pseudo-values CI: 0.212-0.849) (P = 0.007). This study demonstrates the application of WGM to understanding the epidemiology of hospital-associated K. pneumoniae. Utilizing a combination of WGM and WGS, we also present here the first longitudinal genomic characterization of the highly dynamic carbapenem-resistant ST383 K. pneumoniae clone that is rapidly gaining importance in Europe. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial

Informal 'Sorter' Houses: A qualitative insight of the 'shooting gallery' phenomenon in a UK setting.

PubMed

Parkin, Stephen; Coomber, Ross

2009-12-01

This paper considers the 'shooting gallery' phenomenon and presents findings from a sample of injecting drug users with experience of attending such premises in the South-West of England (UK). Due to the reciprocal relationship within these settings, involving the provision of drugs for place, the term Informal Sorter House has been coined by the authors. The social organisation and associative health risks within Informal Sorter Houses were found to have resounding similarities with those previously identified within American settings. However, several differences were also noted. Namely, Informal Sorter Houses appear to be located within a continuum of control that contains regulated, unregulated, and restored injecting environments and accordingly, it is suggested that such environments are in constant flux. A further difference relates to drug-user activism identified within such settings. This involves the establishment of an informal, street-based harm reduction practice that provides potential for future service development.

Final Report Advanced Quasioptical Launcher System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffrey Neilson

2010-04-30

This program developed an analytical design tool for designing antenna and mirror systems to convert whispering gallery RF modes to Gaussian or HE11 modes. Whispering gallery modes are generated by gyrotrons used for electron cyclotron heating of fusion plasmas in tokamaks. These modes cannot be easily transmitted and must be converted to free space or waveguide modes compatible with transmission line systems.This program improved the capability of SURF3D/LOT, which was initially developed in a previous SBIR program. This suite of codes revolutionized quasi-optical launcher design, and this code, or equivalent codes, are now used worldwide. This program added functionality tomore » SURF3D/LOT to allow creating of more compact launcher and mirror systems and provide direct coupling to corrugated waveguide within the vacuum envelope of the gyrotron. Analysis was also extended to include full-wave analysis of mirror transmission line systems. The code includes a graphical user interface and is available for advanced design of launcher systems.« less

Walk, Look, Remember: The Influence of the Gallery's Spatial Layout on Human Memory for an Art Exhibition.

PubMed

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.

Parity-Time-Symmetric Whispering-Gallery Microcavities

DTIC Science & Technology

2014-04-06

Stone, A. D. PT - symmetry breaking and laser -absorber modes in optical scattering systems. Phys. Rev. Lett. 106, 093902 (2011). 31. Liang, G. Q. & Chong...see that only when the PT - symmetry is broken, the field is localized in the active resonator and thus the signal at the output port of the fiber ...peaks. Fig.S9. Localization of the optical field in the active resonator in the broken- PT symmetry phase. Fiber taper waveguide with ports 1 and

Chalcogenide glass sensors for bio-molecule detection

NASA Astrophysics Data System (ADS)

Lucas, Pierre; Coleman, Garrett J.; Cantoni, Christopher; Jiang, Shibin; Luo, Tao; Bureau, Bruno; Boussard-Pledel, Catherine; Troles, Johann; Yang, Zhiyong

2017-02-01

Chalcogenide glasses constitute the only class of materials that remain fully amorphous while exhibiting broad optical transparency over the full infrared region from 2-20 microns. As such, they can be shaped into complex optical elements while retaining a clear optical window that encompass the vibrational signals of virtually any molecules. Chalcogenide glasses are therefore ideal materials for designing biological and chemical sensors based on vibrational spectroscopy. In this paper we review the properties of these glasses and the corresponding design of optical elements for bio-chemical sensing. Amorphous chalcogenides offer a very wide compositional landscape that permit to tune their physical properties to match specific demands for the production of optical devices. This includes tailoring the infrared window over specific ranges of wavelength such as the long-wave infrared region to capture important vibrational signal including the "signature region" of micro-organisms or the bending mode of CO2 molecules. Additionally, compositional engineering enables tuning the viscosity-temperature dependence of the glass melt in order to control the rheological properties that are fundamental to the production of glass elements. Indeed, exquisite control of the viscosity is key to the fabrication process of many optical elements such as fiber drawing, lens molding, surface embossing or reflow of microresonators. Optimal control of these properties then enables the design and fabrication of optimized infrared sensors such as Fiber Evanescent Wave Spectroscopy (FEWS) sensors, Whispering Gallery Modes (WGM) micro-resonator sensors, nanostructured surfaces for integrated optics and surface-enhanced processes, or lens molding for focused collection of infrared signals. Many of these sensor designs can be adapted to collect and monitor the vibrational signal of live microorganisms to study their metabolism in controlled environmental conditions. Further materials

Development of optical micro resonance based sensor for detection and identification of microparticles and biological agents

NASA Astrophysics Data System (ADS)

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

2009-05-01

A novel emerging technique for the label-free analysis of nanoparticles including biomolecules using optical micro cavity resonance of whispering-gallery-type modes is being developed. Schemes of such a method based on microsphere melted by laser on the tip of a standard single mode fiber optical cable with a laser and free microsphere matrix have been developed. Using a calibration principal of ultra high resolution spectroscopy based on such a scheme the method is being transformed to make further development for microbial application. The sensitivity of developed schemes has been tested to refractive index changes by monitoring the magnitude of the whispering gallery modes spectral shift. Water solutions of ethanol, glucose, vitamin C and biotin have been used. Some other schemes using similar principals: stand-alone, array and matrix microsphere resonators, liquid core optical ring resonators are also being under development. The influences of the gap in whispering-gallery modes on energy coupling, resonance quality and frequency have been investigated. An optimum gap for sensing applications has been defined at the half maximum energy coupling where both the Q factor and coupling efficiency are high and the resonance frequency is little affected by the gap variation. Developed schemes 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.

Whispering gallery modes in photoluminescence and Raman spectra of a spherical microcavity with CdTe quantum dots: anti-Stokes emission and interference effects

PubMed Central

Gaponik, Nikolai; Gerlach, Matthias; Donegan, John F; Savateeva, Diana; Rogach, Andrey L

2006-01-01

We have studied the photoluminescence and Raman spectra of a system consisting of a polystyrene latex microsphere coated by CdTe colloidal quantum dots. The cavity-induced enhancement of the Raman scattering allows the observation of Raman spectra from only a monolayer of CdTe quantum dots. Periodic structure with very narrow peaks in the photoluminescence spectra of a single microsphere was detected both in the Stokes and anti-Stokes spectral regions, arising from the coupling between the emission of quantum dots and spherical cavity modes.

Parallel inversion of a massive ERT data set to characterize deep vadose zone contamination beneath former nuclear waste infiltration galleries at the Hanford Site B-Complex (Invited)

NASA Astrophysics Data System (ADS)

Johnson, T.; Rucker, D. F.; Wellman, D.

2013-12-01

The Hanford Site, located in south-central Washington, USA, originated in the early 1940's as part of the Manhattan Project and produced plutonium used to build the United States nuclear weapons stockpile. In accordance with accepted industrial practice of that time, a substantial portion of relatively low-activity liquid radioactive waste was disposed of by direct discharge to either surface soil or into near-surface infiltration galleries such as cribs and trenches. This practice was supported by early investigations beginning in the 1940s, including studies by Geological Survey (USGS) experts, whose investigations found vadose zone soils at the site suitable for retaining radionuclides to the extent necessary to protect workers and members of the general public based on the standards of that time. That general disposal practice has long since been discontinued, and the US Department of Energy (USDOE) is now investigating residual contamination at former infiltration galleries as part of its overall environmental management and remediation program. Most of the liquid wastes released into the subsurface were highly ionic and electrically conductive, and therefore present an excellent target for imaging by Electrical Resistivity Tomography (ERT) within the low-conductivity sands and gravels comprising Hanford's vadose zone. In 2006, USDOE commissioned a large scale surface ERT survey to characterize vadose zone contamination beneath the Hanford Site B-Complex, which contained 8 infiltration trenches, 12 cribs, and one tile field. The ERT data were collected in a pole-pole configuration with 18 north-south trending lines, and 18 east-west trending lines ranging from 417m to 816m in length. The final data set consisted of 208,411 measurements collected on 4859 electrodes, covering an area of 600m x 600m. Given the computational demands of inverting this massive data set as a whole, the data were initially inverted in parts with a shared memory inversion code, which

Chaos-assisted broadband momentum transformation in optical microresonators.

PubMed

Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

2017-10-20

The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Three-mode mode-division-multiplexing passive optical network over 12-km low mode-crosstalk FMF using all-fiber mode MUX/DEMUX

NASA Astrophysics Data System (ADS)

Ren, Fang; Li, Juhao; Wu, Zhongying; Hu, Tao; Yu, Jinyi; Mo, Qi; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

2017-01-01

We propose three-mode mode-division-multiplexing passive optical network (MDM-PON) based on low mode-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). The FMF with step-index profile is designed and fabricated for effectively three-independent-spatial-mode transmission and low mode-crosstalk for MDM-PON transmission. The all-fiber mode MUX/DEMUX are composed of cascaded mode selective couplers (MSCs), which simultaneously multiplex or demultiplex multiple modes. Based on the low mode-crosstalk of the FMF and all-fiber mode MUX/DEMUX, each optical network unit (ONU) communicates with the optical line terminal (OLT) independently utilizing a different optical linearly polarized (LP) spatial mode in MDM-PON system. We experimentally demonstrate MDM-PON transmission of three independent-spatial-modes over 12-km FMF with 10-Gb/s optical on-off keying (OOK) signal and direct detection.

Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission.

PubMed

Hanzawa, Nobutomo; Saitoh, Kuimasa; Sakamoto, Taiji; Matsui, Takashi; Tsujikawa, Kyozo; Koshiba, Masanori; Yamamoto, Fumihiko

2013-11-04

We proposed a PLC-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The mode MUX/DEMUX including a mode conversion function with an asymmetric parallel waveguide can be realized by matching the effective indices of the LP(01) and LP(11) modes of two waveguides. We report the design of a mode MUX/DEMUX that can support C-band WDM-MDM transmission. The fabricated mode MUX/DEMUX realized a low insertion loss of less than 1.3 dB and high a mode extinction ratio that exceeded 15 dB. We used the fabricated mode MUX/DEMUX to achieve a successful 2 mode x 4 wavelength x 10 Gbps transmission over a 9 km two-mode fiber with a penalty of less than 1 dB.

High-Q Microsphere Cavity for Laser Stabilization and Optoelectronic Microwave

NASA Technical Reports Server (NTRS)

Ilchenko, V.; Yao, X.; Maleki, L.

1999-01-01

With submillimeter size and optical Q up to 10(sup 10), microspheres with whispering-gallery (WG) modes are attractive new component for fiber-optics/photonics applications and a potential core in ultra-compact high-spectral-purity optical and microwave oscillators.

Towards a fully integrated optical gyroscope using whispering gallery modes resonators

NASA Astrophysics Data System (ADS)

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.

Raman lasing in As₂S₃ high-Q whispering gallery mode resonators.

PubMed

Vanier, Francis; Rochette, Martin; Godbout, Nicolas; Peter, Yves-Alain

2013-12-01

We report the first observation of a nonlinear process in a chalcogenide microresonator. Raman scattering and stimulated Raman scattering leading to laser oscillation is observed in microspheres made of As₂S₃. The coupled pump power threshold is as low as 13 μW using a pump wavelength of 1550 nm. The quality factor of the chalcogenide microresonator is also the highest ever reported with Q>7×10(7).

Fundamental-mode MMF transmission enabled by mode conversion

NASA Astrophysics Data System (ADS)

Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Jinglong; Ren, Fang; Mo, Qi; Yu, Jinyi; Li, Zhengbin; Chen, Zhangyuan; He, Yongqi

2018-03-01

Modal dispersion in conventional multi-mode fiber (MMF) will cause serious signal degradation and an effective solution is to restrict the signal transmission in the fundamental mode of MMF. In this paper, unlike previous methods by filtering out higher-order modes, we propose to adopt low-modal-crosstalk mode converters to realize fundamental-mode MMF transmission. We design and fabricate all-fiber mode-selective couplers (MSC), which perform mode conversion between the fundamental mode in single-mode fiber (SMF) and fundamental mode in MMF. The proposed scheme is experimentally compared with center launching method under different MMF links and then its wavelength division multiplexing (WDM) transmission performance is investigated. Experimental results indicate that the proposed mode conversion scheme could achieve better transmission performance and works well for the whole C-band.

PLC-based mode multi/demultiplexers for mode division multiplexing

NASA Astrophysics Data System (ADS)

Saitoh, Kunimasa; Hanzawa, Nobutomo; Sakamoto, Taiji; Fujisawa, Takeshi; Yamashita, Yoko; Matsui, Takashi; Tsujikawa, Kyozo; Nakajima, Kazuhide

2017-02-01

Recently developed PLC-based mode multi/demultiplexers (MUX/DEMUXs) for mode division multiplexing (MDM) transmission are reviewed. We firstly show the operation principle and basic characteristics of PLC-based MUX/DEMUXs with an asymmetric directional coupler (ADC). We then demonstrate the 3-mode (2LP-mode) multiplexing of the LP01, LP11a, and LP11b modes by using fabricated PLC-based mode MUX/DEMUX on one chip. In order to excite LP11b mode in the same plane, a PLC-based LP11 mode rotator is introduced. Finally, we show the PLC-based 6-mode (4LP-mode) MUX/DEMUX with a uniform height by using ADCs, LP11 mode rotators, and tapered waveguides. It is shown that the LP21a mode can be excited from the LP11b mode by using ADC, and the two nearly degenerated LP21b and LP02 modes can be (de)multiplexed separately by using tapered mode converter from E13 (E31) mode to LP21b (LP02) mode.

Web-based scoring of the dicentric assay, a collaborative biodosimetric scoring strategy for population triage in large scale radiation accidents.

PubMed

Romm, H; Ainsbury, E; Bajinskis, A; Barnard, S; Barquinero, J F; Barrios, L; Beinke, C; Puig-Casanovas, R; Deperas-Kaminska, M; Gregoire, E; Oestreicher, U; Lindholm, C; Moquet, J; Rothkamm, K; Sommer, S; Thierens, H; Vral, A; Vandersickel, V; Wojcik, A

2014-05-01

In the case of a large scale radiation accident high throughput methods of biological dosimetry for population triage are needed to identify individuals requiring clinical treatment. The dicentric assay performed in web-based scoring mode may be a very suitable technique. Within the MULTIBIODOSE EU FP7 project a network is being established of 8 laboratories with expertise in dose estimations based on the dicentric assay. Here, the manual dicentric assay was tested in a web-based scoring mode. More than 23,000 high resolution images of metaphase spreads (only first mitosis) were captured by four laboratories and established as image galleries on the internet (cloud). The galleries included images of a complete dose effect curve (0-5.0 Gy) and three types of irradiation scenarios simulating acute whole body, partial body and protracted exposure. The blood samples had been irradiated in vitro with gamma rays at the University of Ghent, Belgium. Two laboratories provided image galleries from Fluorescence plus Giemsa stained slides (3 h colcemid) and the image galleries from the other two laboratories contained images from Giemsa stained preparations (24 h colcemid). Each of the 8 participating laboratories analysed 3 dose points of the dose effect curve (scoring 100 cells for each point) and 3 unknown dose points (50 cells) for each of the 3 simulated irradiation scenarios. At first all analyses were performed in a QuickScan Mode without scoring individual chromosomes, followed by conventional scoring (only complete cells, 46 centromeres). The calibration curves obtained using these two scoring methods were very similar, with no significant difference in the linear-quadratic curve coefficients. Analysis of variance showed a significant effect of dose on the yield of dicentrics, but no significant effect of the laboratories, different methods of slide preparation or different incubation times used for colcemid. The results obtained to date within the MULTIBIODOSE

Emergence: A Planetarium and Art Gallery Collaboration Between Artist, Astronomer, and Musician

NASA Astrophysics Data System (ADS)

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.

Mode coupling at connectors in mode-division multiplexed transmission over few-mode fiber.

PubMed

Vuong, Jordi; Ramantanis, Petros; Frignac, Yann; Salsi, Massimiliano; Genevaux, Philippe; Bendimerad, Djalal F; Charlet, Gabriel

2015-01-26

In mode-division multiplexed (MDM) transmission systems, mode coupling is responsible for inter-modal crosstalk. We consider the transmission of modulated signals over a few-mode fiber (FMF) having low mode coupling and large differential mode group delay in the presence of a non-ideal fiber connection responsible for extra mode coupling. In this context, we first analytically derive the coupling matrix of the multimode connector and we numerically study the dependence of the matrix coefficients as a function of the butt-joint connection characteristics. The numerical results are then validated through an experiment with a five-mode setup. Finally, through numerical simulations, we assess the impact of the connector on the signal quality investigating different receiver digital signal processing (DSP) schemes.

Optimization of few-mode-fiber based mode converter for mode division multiplexing transmission

NASA Astrophysics Data System (ADS)

Xie, Yiwei; Fu, Songnian; Zhang, Minming; Tang, M.; Shum, P.; Liu, Deming

2013-10-01

Few-mode-fiber (FMF) based mode division multiplexing (MDM) is a promising technique to further increase the transmission capacity of single mode fibers. We propose and numerically investigate a fiber-optical mode converter (MC) using long period gratings (LPGs) fabricated on the FMF by point-by-point CO2 laser inscription technique. In order to precisely excite three modes (LP01, LP11, and LP02), both untilted LPG and tilted LPG are comprehensively optimized through the length, index modulation depth, and tilt angle of the LPG in order to achieve a mode contrast ratio (MCR) of more than 20 dB with less wavelength dependence. It is found that the proposed MCs have obvious advantages of high MCR, low mode crosstalk, easy fabrication and maintenance, and compact size.

Constraining primordial vector mode from B-mode polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saga, Shohei; Ichiki, Kiyotomo; Shiraishi, Maresuke, E-mail: saga.shohei@nagoya-u.jp, E-mail: maresuke.shiraishi@pd.infn.it, E-mail: ichiki@a.phys.nagoya-u.ac.jp

The B-mode polarization spectrum of the Cosmic Microwave Background (CMB) may be the smoking gun of not only the primordial tensor mode but also of the primordial vector mode. If there exist nonzero vector-mode metric perturbations in the early Universe, they are known to be supported by anisotropic stress fluctuations of free-streaming particles such as neutrinos, and to create characteristic signatures on both the CMB temperature, E-mode, and B-mode polarization anisotropies. We place constraints on the properties of the primordial vector mode characterized by the vector-to-scalar ratio r{sub v} and the spectral index n{sub v} of the vector-shear power spectrum,more » from the Planck and BICEP2 B-mode data. We find that, for scale-invariant initial spectra, the ΛCDM model including the vector mode fits the data better than the model including the tensor mode. The difference in χ{sup 2} between the vector and tensor models is Δχ{sup 2} = 3.294, because, on large scales the vector mode generates smaller temperature fluctuations than the tensor mode, which is preferred for the data. In contrast, the tensor mode can fit the data set equally well if we allow a significantly blue-tilted spectrum. We find that the best-fitting tensor mode has a large blue tilt and leads to an indistinct reionization bump on larger angular scales. The slightly red-tilted vector mode supported by the current data set can also create O(10{sup -22})-Gauss magnetic fields at cosmological recombination. Our constraints should motivate research that considers models of the early Universe that involve the vector mode.« less

Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

NASA Astrophysics Data System (ADS)

Ren, Fang; Yu, Jinyi; Wang, Jianping

2018-05-01

We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N × 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured.

An SMS (single mode - multi mode - single mode) fiber structure for vibration sensing

NASA Astrophysics Data System (ADS)

Waluyo, T. B.; Bayuwati, D.

2017-04-01

We describe an SMS (single mode - multi mode - single mode) fiber structure to be used in a vibration sensing system. The fiber structure was fabricated by splicing a section (about 300 mm in length) of a step index multi mode fiber between two single mode fibers obtained from a communication grade fiber patchcord. Interference between higher order modes occurs while light from a narrow band light source travels along the multi mode fiber. When the multi mode fiber vibrates, the refractive index profile is changed because of the photo-elastics effect and the amplitude of the interference pattern is changed accordingly. To simulate a vibrating structure we used a loudspeaker to vibrate a wooden table. By using a digital oscilloscope, we recorded and analysed the vibrating signals obtained from the SMS fiber structure as well as from a GS-32CT geophone for referencing. We observed that this SMS fiber structure was potential to be used in a vibration sensing system with a measurement range from 30 to 180 Hz with inherent optical fiber sensor advantages such as light weight, immune to electromagnetic interference, and no electricity in the sensing part.

Intracellular microlasers

NASA Astrophysics Data System (ADS)

Humar, Matjaž; Hyun Yun, Seok

2015-09-01

Optical microresonators, which confine light within a small cavity, are widely exploited for various applications ranging from the realization of lasers and nonlinear devices to biochemical and optomechanical sensing. Here we use microresonators and suitable optical gain materials inside biological cells to demonstrate various optical functions in vitro including lasing. We explore two distinct types of microresonator—soft and hard—that support whispering-gallery modes. Soft droplets formed by injecting oil or using natural lipid droplets support intracellular laser action. The laser spectra from oil-droplet microlasers can chart cytoplasmic internal stress (˜500 pN μm-2) and its dynamic fluctuations at a sensitivity of 20 pN μm-2 (20 Pa). In a second form, whispering-gallery modes within phagocytized polystyrene beads of different sizes enable individual tagging of thousands of cells easily and, in principle, a much larger number by multiplexing with different dyes.

Mode evolution in polarization maintain few mode fibers and applications in mode-division-multiplexing systems

NASA Astrophysics Data System (ADS)

Li, Yan; Zeng, Xinglin; Mo, Qi; Li, Wei; Liu, Zhijian; Wu, Jian

2016-10-01

In few-mode polarization-maintaining-fiber (FM-PMF), the effective-index splitting exists not only between orthogonally polarization state but also between degenerated modes within a high-order mode group. Hence besides the polarization state evolution, the mode patterns in each LP set are need to be analyzed. In this letter, the completed firstorder mode (LP11 mode) evolution in PM-FMF is analyzed and represented by analogous Jones vector and Poincarésphere respectively. Furthermore, with Jones matrix analysis, the modal dynamics in FM-PMFs is conveniently analyzed. The conclusions are used to propose a PM-FMF based LP11 mode rotator and an PM-FMF based OAM generator. Both simulation and experiments are conducted to investigate performance of the two devices.

Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jiawei; Huang, Wenhua; Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024

2015-03-16

A dual-cavity TM{sub 02}–TM{sub 01} mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM{sub 01} mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM{sub 01} mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM{sub 01} mode feedback.

Single-mode fiber laser based on core-cladding mode conversion.

PubMed

Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

2008-02-15

A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber

PubMed Central

Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W.

2011-01-01

The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg–Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers. PMID:21731106

Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber.

PubMed

Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W

2011-01-01

The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg-Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers.

DecouplingModes: Passive modes amplitudes

NASA Astrophysics Data System (ADS)

Shaw, J. Richard; Lewis, Antony

2018-01-01

DecouplingModes calculates the amplitude of the passive modes, which requires solving the Einstein equations on superhorizon scales sourced by the anisotropic stress from the magnetic fields (prior to neutrino decoupling), and the magnetic and neutrino stress (after decoupling). The code is available as a Mathematica notebook.

Modeling of the whispering gallery mode in microdisk and microgear resonators using a Toeplitz matrix formalism for single-photon source

NASA Astrophysics Data System (ADS)

Attia, Moez; Gueddana, Amor; Chatta, Rihab; Morand, Alain

2013-09-01

The work presented in this paper develops a new formalism to design microdisks and microgears structures. The main objective is to study the optics and geometrics parameters influence on the microdisks and microgears structures resonance behavior. This study is conducted to choice a resonance structure with height quality factor Q to be associated with Quantum dot to form a single photon source. This new method aims to design resonant structures that are simpler and requires less computing performances than FDTD and Floquet Block methods. This formalism is based on simplifying Fourier transformed and using toeplitz matrix writing. This new writing allows designing all kind of resonance structures with any defect and any modification. In other study we have design a quantum dot emitting a photon at 1550 nm of the fundamental mode, but the quantum dot emits other photons at other wavelengths. The focus of the resonant structure and the quantum dot association is the resonance of the photon at 1550 nm and the elimination of all other photons with others energies. The quantum dot studied in [1] is an InAs/GaAs quantum dot, we design an GaAS microdisk and microgear and we compare the quality factor Q of this two structures and we conclude that the microgear is more appropriated to be associate to the quantum dot and increase the probability P1 to obtain a single photon source at 1550 nm and promotes the obtaining of single photon. The performance improving of the resonant structure is able to increase the success of quantum applications such as quantum gates based on single photon source.

Lommel modes

NASA Astrophysics Data System (ADS)

Kovalev, Alexey A.; Kotlyar, Victor V.

2015-03-01

We study a non-paraxial family of nondiffracting laser beams whose complex amplitude is proportional to an n-th order Lommel function of two variables. These beams are referred to as Lommel modes. Explicit analytical relations for the angular spectrum of plane waves and orbital angular momentum of the Lommel beams have been derived. The even (n=2p) and odd (n=2p+1) Lommel modes are mutually orthogonal, as are the Lommel modes characterized by different projections of the wave vector on the optical axis. At a definite parameter, the Lommel modes change to conventional Bessel beams. Asymmetry of the Lommel modes depends on a complex parameter с, with its modulus in the polar notation defining the intensity pattern in the beam‧s cross-section and the argument defining the angle of rotation of the intensity pattern about the optical axis. If the parameter с is real or purely imaginary, the transverse intensity component of the Lommel modes is specularly symmetric about the Cartesian coordinate axes. Besides, with the modulus of the с parameter increasing from 0 to 1, the orbital angular momentum of the Lommel modes increases from a finite value proportional to the topological charge n to infinity. The orbital angular momentum of the Lommel modes undergoes continuous variations, in contrast to its discrete changes in the Bessel modes.

Fabrication and Testing of Microfluidic Optomechanical Oscillators

PubMed Central

Han, Kewen; Kim, Kyu Hyun; Kim, Junhwan; Lee, Wonsuk; Liu, Jing; Fan, Xudong; Carmon, Tal; Bahl, Gaurav

2014-01-01

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained. PMID:24962013

Investigation of Optical Cavity Modes and Ultrafast Carrier Dynamics in Zinc Oxide Rods Using Second-Harmonic Generation and Transient Absorption Pump-Probe Microscopy

NASA Astrophysics Data System (ADS)

Mehl, Brian Peter

The polydispersity intrinsic to nanoscale and microscale semiconductor materials poses a major challenge to using individual objects as building blocks for device applications. The ability to manipulate the shape of ZnO structures is enormous, making it an ideal material for studying shape-dependent phenomena. We have built a nonlinear microscope used to directly image optical cavity modes in ZnO rods using second-harmonic generation. Images of second-harmonic generation in needle-shaped ZnO rods obtained from individual structures show areas of enhanced second-harmonic intensity along the longitudinal axis of the rod that are periodically distributed and symmetrically situated relative to the rod midpoint. The spatial modulation is a direct consequence of the fundamental optical field coupling into standing wave resonator modes of the ZnO structure, leading to an enhanced backscattered second-harmonic condition that cannot be achieved in bulk ZnO. A more complicated second-harmonic image is observed when excitation is below the band gap, which is attributed to whispering gallery modes. Additionally, the nonlinear microscope was combined with transient absorption pump-probe to follow the electron-hole recombination dynamics at different points within individual needle-shaped ZnO rods to characterize spatial differences in dynamical behavior. The results from pump-probe experiments are correlated with spatially resolved ultrafast emission measurements, and scanning electron microscopy provides structural details. Dramatically different electron-hole recombination dynamics are observed in the narrow tips compared to the interior, with the ends exhibiting a greater propensity for electron-hole plasma formation and faster recombination of carriers across the band gap that stem from a physical confinement of the charge carriers. In the interior of the rod, a greater fraction of the electron-hole recombination is trap-mediated and occurs on a significantly longer time

Adiabatically tapered microstructured mode converter for selective excitation of the fundamental mode in a few mode fiber.

PubMed

Taher, Aymen Belhadj; Di Bin, Philippe; Bahloul, Faouzi; Tartaret-Josnière, Etienne; Jossent, Mathieu; Février, Sébastien; Attia, Rabah

2016-01-25

We propose a new technique to selectively excite the fundamental mode in a few mode fiber (FMF). This method of excitation is made from a single mode fiber (SMF) which is inserted facing the FMF into an air-silica microstructured cane before the assembly is adiabatically tapered. We study theoretically and numerically this method by calculating the effective indices of the propagated modes, their amplitudes along the taper and the adiabaticity criteria, showing the ability to achieve an excellent selective excitation of the fundamental mode in the FMF with negligible loss. We experimentally demonstrate that the proposed solution provides a successful mode conversion and allows an almost excellent fundamental mode excitation in the FMF (representing 99.8% of the total power).

Investigation on the oscillation modes in a thermoacoustic Stirling prime mover: mode stability and mode transition

NASA Astrophysics Data System (ADS)

Yu, Z. B.; Li, Q.; Chen, X.; Guo, F. Z.; Xie, X. J.; Wu, J. H.

2003-12-01

The purpose of this paper is to investigate the stability of oscillation modes in a thermoacoustic Stirling prime mover, which is a combination of looped tube and resonator. Two modes, with oscillation frequencies of 76 and 528 Hz, have been observed, stabilities of which are widely different. The stability of the high frequency mode (HFM) is affected by low frequency mode (LFM) strongly. Once the LFM is excited when the HFM is present, the HFM will be gradually slaved and suppressed by the LFM. The details of the transition from HFM to LFM have been described. The two stability curves of the two modes have been measured. Mean pressure Pm is an important control parameter influencing the mode stability in the tested system.

Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance

PubMed Central

Torrezan, Antonio C.; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Griffin, Robert G.; Barnes, Alexander B.

2012-01-01

The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high-order axial modes TE11,2,q. The minimum start current is 27 mA. Power and frequency tuning measurements as a function of the electron cyclotron frequency have also been carried out. A smooth frequency tuning range of 1 GHz was obtained for the operating second-harmonic mode either by magnetic field tuning or beam voltage tuning. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. PMID:23761938

Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance

PubMed Central

Torrezan, Antonio C.; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Barnes, Alexander B.; Griffin, Robert G.

2011-01-01

The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high-order axial modes TE11,2,q. The minimum start current is 27 mA. Power and frequency tuning measurements as a function of the electron cyclotron frequency have also been carried out. A smooth frequency tuning range of 1 GHz was obtained for the operating second-harmonic mode either by magnetic field tuning or beam voltage tuning. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. PMID:21243088

Nanomechanical modeling of interfaces of polyvinyl alcohol (PVA)/clay nanocomposite

NASA Astrophysics Data System (ADS)

Paliwal, Bhasker; Lawrimore, William B.; Chandler, Mei Q.; Horstemeyer, Mark F.

2017-05-01

We study interfacial debonding of several representative structures of polyvinyl alcohol (PVA)/pyrophillite-clay systems - both gallery-interface (polymer/clay interface in the interlayer region containing polymer between clay layers stacked parallel to each other) and matrix-interphase (polymer/clay interphase-region when individual clay layers are well separated and dispersed in the polymer matrix) - using molecular dynamics simulations, while explicitly accounting for shearing/sliding (i.e. Mode-II) deformation mode. Ten nanocomposite geometries (five 2-D periodic structures for tension and five 1-D periodic structures for shearing) were constructed to quantify the structure-property relations by varying the number density of polymer chains, length of polymer chains and model dimensions related to the interface deformation. The results were subsequently mapped into a cohesive traction-separation law, including evaluation of peak traction and work of separation that are used to characterise the interface load transfer for larger length scale micromechanical models. Results suggest that under a crack nucleation opening mode (i.e. Mode-I), the matrix-interphase exhibits noticeably greater strength and a greater work of separation compared to the gallery-interface; however, they were similar under the shearing/sliding mode of deformation. When compared to shearing/sliding, the tensile peak opening mode stresses were considerably greater but the displacement at the peak stress, the displacement at the final failure and the work of separation were considerably lower. Results also suggest that PVA/clay nanocomposites with higher degree of exfoliation compared with nanocomposites with higher clay-intercalation can potentially display higher strength under tension-dominated loading for a given clay volume fraction.

PLC-based LP₁₁ mode rotator for mode-division multiplexing transmission.

PubMed

Saitoh, Kunimasa; Uematsu, Takui; Hanzawa, Nobutomo; Ishizaka, Yuhei; Masumoto, Kohei; Sakamoto, Taiji; Matsui, Takashi; Tsujikawa, Kyozo; Yamamoto, Fumihiko

2014-08-11

A PLC-based LP11 mode rotator is proposed. The proposed mode rotator is composed of a waveguide with a trench that provides asymmetry of the waveguide. Numerical simulations show that converting LP11a (LP11b) mode to LP11b (LP11a) mode can be achieved with high conversion efficiency (more than 90%) and little polarization dependence over a wide wavelength range from 1450 nm to 1650 nm. In addition, we fabricate the proposed LP11 mode rotator using silica-based PLC. It is confirmed that the fabricated mode rotator can convert LP11a mode to LP11b mode over a wide wavelength range.

Competition and evolution of dielectric waveguide mode and plasmonic waveguide mode

NASA Astrophysics Data System (ADS)

Yuan, Sheng-Nan; Fang, Yun-Tuan

2017-10-01

In order to study the coupling and evolution law of the waveguide mode and two plasmonic surface modes, we construct a line defect waveguide based on hexagonal honeycomb plasmonic photonic crystal. Through adjusting the radius of the edge dielectric rods, the competition and evolution behaviors occur between dielectric waveguide mode and plasmonic waveguide mode. There are three status: only plasmonic waveguide modes occur for rA < 0.09a; only dielectric waveguide modes occur for rA > 0.25a; two kinds of modes coexist for 0.09a < rA < 0.25a. The plasmonic waveguide mode has advantages in achieving slow light.

Single-Mode VCSELs

NASA Astrophysics Data System (ADS)

Larsson, Anders; Gustavsson, Johan S.

The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

Shooting gallery operation in the context of establishing a medically supervised injecting center: Sydney, Australia.

PubMed

Kimber, Jo; Dolan, Kate

2007-03-01

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.

Validation of Mode-S Meteorological Routine Air Report aircraft observations

NASA Astrophysics Data System (ADS)

Strajnar, B.

2012-12-01

The success of mesoscale data assimilation depends on the availability of three-dimensional observations with high spatial and temporal resolution. This paper describes an example of such observations, available through Mode-S air traffic control system composed of ground radar and transponders on board the aircraft. The meteorological information is provided by interrogation of a dedicated meteorological data register, called Meteorological Routine Air Report (MRAR). MRAR provides direct measurements of temperature and wind, but is only returned by a small fraction of aircraft. The quality of Mode-S MRAR data, collected at the Ljubljana Airport, Slovenia, is assessed by its comparison with AMDAR and high-resolution radiosonde data sets, which enable high- and low-level validation, respectively. The need for temporal smoothing of raw Mode-S MRAR data is also studied. The standard deviation of differences between smoothed Mode-S MRAR and AMDAR is 0.35°C for temperature, 0.8 m/s for wind speed and below 10 degrees for wind direction. The differences with respect to radiosondes are larger, with standard deviations of approximately 1.7°C, 3 m/s and 25 degrees for temperature, wind speed and wind direction, respectively. It is concluded that both wind and temperature observations from Mode-S MRAR are accurate and therefore potentially very useful for data assimilation in numerical weather prediction models.

Micro-CTvlab: A web based virtual gallery of biological specimens using X-ray microtomography (micro-CT)

PubMed Central

Faulwetter, Sarah; Chatzinikolaou, Eva; Michalakis, Nikitas; Filiopoulou, Irene; Minadakis, Nikos; Panteri, Emmanouela; Perantinos, George; Gougousis, Alexandros; Arvanitidis, Christos

2016-01-01

Abstract Background During recent years, X-ray microtomography (micro-CT) has seen an increasing use in biological research areas, such as functional morphology, taxonomy, evolutionary biology and developmental research. Micro-CT is a technology which uses X-rays to create sub-micron resolution images of external and internal features of specimens. These images can then be rendered in a three-dimensional space and used for qualitative and quantitative 3D analyses. However, the online exploration and dissemination of micro-CT datasets are rarely made available to the public due to their large size and a lack of dedicated online platforms for the interactive manipulation of 3D data. Here, the development of a virtual micro-CT laboratory (Micro-CTvlab) is described, which can be used by everyone who is interested in digitisation methods and biological collections and aims at making the micro-CT data exploration of natural history specimens freely available over the internet. New information The Micro-CTvlab offers to the user virtual image galleries of various taxa which can be displayed and downloaded through a web application. With a few clicks, accurate, detailed and three-dimensional models of species can be studied and virtually dissected without destroying the actual specimen. The data and functions of the Micro-CTvlab can be accessed either on a normal computer or through a dedicated version for mobile devices. PMID:27956848

Micro-CTvlab: A web based virtual gallery of biological specimens using X-ray microtomography (micro-CT).

PubMed

Keklikoglou, Kleoniki; Faulwetter, Sarah; Chatzinikolaou, Eva; Michalakis, Nikitas; Filiopoulou, Irene; Minadakis, Nikos; Panteri, Emmanouela; Perantinos, George; Gougousis, Alexandros; Arvanitidis, Christos

2016-01-01

During recent years, X-ray microtomography (micro-CT) has seen an increasing use in biological research areas, such as functional morphology, taxonomy, evolutionary biology and developmental research. Micro-CT is a technology which uses X-rays to create sub-micron resolution images of external and internal features of specimens. These images can then be rendered in a three-dimensional space and used for qualitative and quantitative 3D analyses. However, the online exploration and dissemination of micro-CT datasets are rarely made available to the public due to their large size and a lack of dedicated online platforms for the interactive manipulation of 3D data. Here, the development of a virtual micro-CT laboratory (Micro-CT vlab ) is described, which can be used by everyone who is interested in digitisation methods and biological collections and aims at making the micro-CT data exploration of natural history specimens freely available over the internet. The Micro-CT vlab offers to the user virtual image galleries of various taxa which can be displayed and downloaded through a web application. With a few clicks, accurate, detailed and three-dimensional models of species can be studied and virtually dissected without destroying the actual specimen. The data and functions of the Micro-CT vlab can be accessed either on a normal computer or through a dedicated version for mobile devices.

Linearly polarized vector modes: enabling MIMO-free mode-division multiplexing.

PubMed

Wang, Lixian; Nejad, Reza Mirzaei; Corsi, Alessandro; Lin, Jiachuan; Messaddeq, Younès; Rusch, Leslie; LaRochelle, Sophie

2017-05-15

We experimentally investigate mode-division multiplexing in an elliptical ring core fiber (ERCF) that supports linearly polarized vector modes (LPV). Characterization show that the ERCF exhibits good polarization maintaining properties over eight LPV modes with effective index difference larger than 1 × 10 -4 . The ERCF further displays stable mode power and polarization extinction ratio when subjected to external perturbations. Crosstalk between the LPV modes, after propagating through 0.9 km ERCF, is below -14 dB. By using six LPV modes as independent data channels, we achieved the transmission of 32 Gbaud QPSK over 0.9 km ERCF without any multiple-input-multiple-output (MIMO) or polarization-division multiplexing (PDM) signal processing.

Comparing mode-crosstalk and mode-dependent loss of laterally displaced orbital angular momentum and Hermite-Gaussian modes for free-space optical communication.

PubMed

Ndagano, Bienvenu; Mphuthi, Nokwazi; Milione, Giovanni; Forbes, Andrew

2017-10-15

There is interest in using orbital angular momentum (OAM) modes to increase the data speed of free-space optical communication. A prevalent challenge is the mitigation of mode-crosstalk and mode-dependent loss that is caused by the modes' lateral displacement at the data receiver. Here, the mode-crosstalk and mode-dependent loss of laterally displaced OAM modes (LG 0,+1 , LG 0,-1 ) are experimentally compared to that of a Hermite-Gaussian (HG) mode subset (HG 0,1 , HG 1,0 ). It is shown, for an aperture larger than the modes' waist sizes, some of the HG modes can experience less mode-crosstalk and mode-dependent loss when laterally displaced along a symmetry axis. It is also shown, over a normal distribution of lateral displacements whose standard deviation is 2× the modes' waist sizes, on average, the HG modes experience 66% less mode-crosstalk and 17% less mode-dependent loss.

Variable optical attenuator and dynamic mode group equalizer for few mode fibers.

PubMed

Blau, Miri; Weiss, Israel; Gerufi, Jonathan; Sinefeld, David; Bin-Nun, Moran; Lingle, Robert; Grüner-Nielsen, Lars; Marom, Dan M

2014-12-15

Variable optical attenuation (VOA) for three-mode fiber is experimentally presented, utilizing an amplitude spatial light modulator (SLM), achieving up to -28dB uniform attenuation for all modes. Using the ability to spatially vary the attenuation distribution with the SLM, we also achieve up to 10dB differential attenuation between the fiber's two supported mode group (LP₀₁ and LP₁₁). The spatially selective attenuation serves as the basis of a dynamic mode-group equalizer (DME), potentially gain-balancing mode dependent optical amplification. We extend the experimental three mode DME functionality with a performance analysis of a fiber supporting 6 spatial modes in four mode groups. The spatial modes' distribution and overlap limit the available dynamic range and performance of the DME in the higher mode count case.

Helicon modes in uniform plasmas. I. Low m modes

NASA Astrophysics Data System (ADS)

Urrutia, J. M.; Stenzel, R. L.

2015-09-01

Helicons are whistler modes with azimuthal wave numbers. They arise in bounded gaseous and solid state plasmas, but the present work shows that very similar modes also exist in unbounded uniform plasmas. The antenna properties determine the mode structure. A simple antenna is a magnetic loop with dipole moment aligned either along or across the ambient background magnetic field B0. For such configurations, the wave magnetic field has been measured in space and time in a large and uniform laboratory plasma. The observed wave topology for a dipole along B0 is similar to that of an m = 0 helicon mode. It consists of a sequence of alternating whistler vortices. For a dipole across B0, an m = 1 mode is excited which can be considered as a transverse vortex which rotates around B0. In m = 0 modes, the field lines are confined to each half-wavelength vortex while for m = 1 modes they pass through the entire wave train. A subset of m = 1 field lines forms two nested helices which rotate in space and time like corkscrews. Depending on the type of the antenna, both m = + 1 and m = -1 modes can be excited. Helicons in unbounded plasmas also propagate transverse to B0. The transverse and parallel wave numbers are about equal and form oblique phase fronts as in whistler Gendrin modes. By superimposing small amplitude fields of several loop antennas, various antenna combinations have been created. These include rotating field antennas, helical antennas, and directional antennas. The radiation efficiency is quantified by the radiation resistance. Since helicons exist in unbounded laboratory plasmas, they can also arise in space plasmas.

EIT in resonator chains: similarities and differences with atomic media

NASA Technical Reports Server (NTRS)

Matsko, A. B.; Maleki, L.; Savchenkov, A. A.; Ilchenko, V. S.

2004-01-01

We theoretically study a parallel configuration of two interacting whispering gallery mode optical resonators and show a narrow-band modal structure as a basis for a widely tunable delay line. For the optimum coupling configuration the system can possess an unusually narrow spectral feature with a much narrower bandwidth than the loaded bandwidth of each individual resonator.

High bandwidth on-chip capacitive tuning of microtoroid resonators

NASA Astrophysics Data System (ADS)

Baker, Christopher G.; Bekker, Christiaan; McAuslan, David L.; Sheridan, Eoin; Bowen, Warwick P.

2016-09-01

We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications.

Enhanced Fano resonance in a non-adiabatic tapered fiber coupled with a microresonator.

PubMed

Zhang, Kun; Wang, Yue; Wu, Yi-Hui

2017-08-01

We achieved enhanced Fano resonance by coupling a bottle resonator with a special non-adiabatic tapered fiber, where there is a high intensity distribution ratio between high-order and fundamental modes in the tapered region, as well as single mode propagation in the waist region. The resonance line shape is theoretically proved to be related to the intensity distribution ratio of the two fiber modes and their phase shift. An enhanced Fano line shape with an extinction ratio over 15 dB is experimentally reached by improving the intensity distribution ratio and tuning the phase shift. The results can remarkably improve the sensitivity of whispering-gallery mode microresonators in the field of optical sensing.

Edge-localized mode avoidance and pedestal structure in I-mode plasmasa)

NASA Astrophysics Data System (ADS)

Walk, J. R.; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E.; Snyder, P. B.; Osborne, T.; Dominguez, A.; Cziegler, I.

2014-05-01

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle Pnet/n ¯e, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of Pnet/n ¯e. This is consistent with targets for increased performance in I-mode, elevating pedestal βp and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs, consistent with the observed suppression of

Flexible Modes Control Using Sliding Mode Observers: Application to Ares I

NASA Technical Reports Server (NTRS)

Shtessel, Yuri B.; Hall, Charles E.; Baev, Simon; Orr, Jeb S.

2010-01-01

The launch vehicle dynamics affected by bending and sloshing modes are considered. Attitude measurement data that are corrupted by flexible modes could yield instability of the vehicle dynamics. Flexible body and sloshing modes are reconstructed by sliding mode observers. The resultant estimates are used to remove the undesirable dynamics from the measurements, and the direct effects of sloshing and bending modes on the launch vehicle are compensated by means of a controller that is designed without taking the bending and sloshing modes into account. A linearized mathematical model of Ares I launch vehicle was derived based on FRACTAL, a linear model developed by NASA/MSFC. The compensated vehicle dynamics with a simple PID controller were studied for the launch vehicle model that included two bending modes, two slosh modes and actuator dynamics. A simulation study demonstrated stable and accurate performance of the flight control system with the augmented simple PID controller without the use of traditional linear bending filters.

Mode selection in square resonator microlasers for widely tunable single mode lasing.

PubMed

Tang, Ming-Ying; Sui, Shao-Shuai; Yang, Yue-De; Xiao, Jin-Long; Du, Yun; Huang, Yong-Zhen

2015-10-19

Mode selection in square resonator semiconductor microlasers is demonstrated by adjusting the width of the output waveguide coupled to the midpoint of one side. The simulation and experimental results reveal that widely tunable single mode lasing can be realized in square resonator microlasers. Through adjusting the width of the output waveguide, the mode interval of the high-Q modes can reach four times of the longitudinal mode interval. Therefore, mode hopping can be efficiently avoided and the lasing wavelength can be tuned continuously by tuning the injection current. For a 17.8-μm-side-length square microlaser with a 1.4-μm-width output waveguide, mode-hopping-free single-mode operation is achieved with a continuous tuning range of 9.2 nm. As a result, the control of the lasing mode is realized for the square microlasers.

Adaptive variational mode decomposition method for signal processing based on mode characteristic

NASA Astrophysics Data System (ADS)

Lian, Jijian; Liu, Zhuo; Wang, Haijun; Dong, Xiaofeng

2018-07-01

Variational mode decomposition is a completely non-recursive decomposition model, where all the modes are extracted concurrently. However, the model requires a preset mode number, which limits the adaptability of the method since a large deviation in the number of mode set will cause the discard or mixing of the mode. Hence, a method called Adaptive Variational Mode Decomposition (AVMD) was proposed to automatically determine the mode number based on the characteristic of intrinsic mode function. The method was used to analyze the simulation signals and the measured signals in the hydropower plant. Comparisons have also been conducted to evaluate the performance by using VMD, EMD and EWT. It is indicated that the proposed method has strong adaptability and is robust to noise. It can determine the mode number appropriately without modulation even when the signal frequencies are relatively close.

Mode division multiplexing using an orbital angular momentum mode sorter and MIMO-DSP over a graded-index few-mode optical fibre

PubMed Central

Huang, Hao; Milione, Giovanni; Lavery, Martin P. J.; Xie, Guodong; Ren, Yongxiong; Cao, Yinwen; Ahmed, Nisar; An Nguyen, Thien; Nolan, Daniel A.; Li, Ming-Jun; Tur, Moshe; Alfano, Robert R.; Willner, Alan E.

2015-01-01

Mode division multiplexing (MDM)– using a multimode optical fiber’s N spatial modes as data channels to transmit N independent data streams – has received interest as it can potentially increase optical fiber data transmission capacity N-times with respect to single mode optical fibers. Two challenges of MDM are (1) designing mode (de)multiplexers with high mode selectivity (2) designing mode (de)multiplexers without cascaded beam splitting’s 1/N insertion loss. One spatial mode basis that has received interest is that of orbital angular momentum (OAM) modes. In this paper, using a device referred to as an OAM mode sorter, we show that OAM modes can be (de)multiplexed over a multimode optical fiber with higher than −15 dB mode selectivity and without cascaded beam splitting’s 1/N insertion loss. As a proof of concept, the OAM modes of the LP11 mode group (OAM−1,0 and OAM+1,0), each carrying 20-Gbit/s polarization division multiplexed and quadrature phase shift keyed data streams, are transmitted 5km over a graded-index, few-mode optical fibre. Channel crosstalk is mitigated using 4 × 4 multiple-input-multiple-output digital-signal-processing with <1.5 dB power penalties at a bit-error-rate of 2 × 10−3. PMID:26450398

Mode division multiplexing using an orbital angular momentum mode sorter and MIMO-DSP over a graded-index few-mode optical fibre.

PubMed

Huang, Hao; Milione, Giovanni; Lavery, Martin P J; Xie, Guodong; Ren, Yongxiong; Cao, Yinwen; Ahmed, Nisar; An Nguyen, Thien; Nolan, Daniel A; Li, Ming-Jun; Tur, Moshe; Alfano, Robert R; Willner, Alan E

2015-10-09

Mode division multiplexing (MDM)- using a multimode optical fiber's N spatial modes as data channels to transmit N independent data streams - has received interest as it can potentially increase optical fiber data transmission capacity N-times with respect to single mode optical fibers. Two challenges of MDM are (1) designing mode (de)multiplexers with high mode selectivity (2) designing mode (de)multiplexers without cascaded beam splitting's 1/N insertion loss. One spatial mode basis that has received interest is that of orbital angular momentum (OAM) modes. In this paper, using a device referred to as an OAM mode sorter, we show that OAM modes can be (de)multiplexed over a multimode optical fiber with higher than -15 dB mode selectivity and without cascaded beam splitting's 1/N insertion loss. As a proof of concept, the OAM modes of the LP11 mode group (OAM-1,0 and OAM+1,0), each carrying 20-Gbit/s polarization division multiplexed and quadrature phase shift keyed data streams, are transmitted 5km over a graded-index, few-mode optical fibre. Channel crosstalk is mitigated using 4 × 4 multiple-input-multiple-output digital-signal-processing with <1.5 dB power penalties at a bit-error-rate of 2 × 10(-3).

Mode division multiplexing using an orbital angular momentum mode sorter and MIMO-DSP over a graded-index few-mode optical fibre

NASA Astrophysics Data System (ADS)

Huang, Hao; Milione, Giovanni; Lavery, Martin P. J.; Xie, Guodong; Ren, Yongxiong; Cao, Yinwen; Ahmed, Nisar; An Nguyen, Thien; Nolan, Daniel A.; Li, Ming-Jun; Tur, Moshe; Alfano, Robert R.; Willner, Alan E.

2015-10-01

Mode division multiplexing (MDM)- using a multimode optical fiber’s N spatial modes as data channels to transmit N independent data streams - has received interest as it can potentially increase optical fiber data transmission capacity N-times with respect to single mode optical fibers. Two challenges of MDM are (1) designing mode (de)multiplexers with high mode selectivity (2) designing mode (de)multiplexers without cascaded beam splitting’s 1/N insertion loss. One spatial mode basis that has received interest is that of orbital angular momentum (OAM) modes. In this paper, using a device referred to as an OAM mode sorter, we show that OAM modes can be (de)multiplexed over a multimode optical fiber with higher than -15 dB mode selectivity and without cascaded beam splitting’s 1/N insertion loss. As a proof of concept, the OAM modes of the LP11 mode group (OAM-1,0 and OAM+1,0), each carrying 20-Gbit/s polarization division multiplexed and quadrature phase shift keyed data streams, are transmitted 5km over a graded-index, few-mode optical fibre. Channel crosstalk is mitigated using 4 × 4 multiple-input-multiple-output digital-signal-processing with <1.5 dB power penalties at a bit-error-rate of 2 × 10-3.

Mode perturbation method for optimal guided wave mode and frequency selection.

PubMed

Philtron, J H; Rose, J L

2014-09-01

With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection for a given application. This "optimal" mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. Since material properties used for modeling work may be estimates, in many cases guided wave mode and frequency selection can be adjusted for increased inspection efficiency in the field. In this paper, a novel mode and frequency perturbation method is described and used to identify optimal mode points based on quantifiable wave characteristics. The technique uses an ultrasonic phased array comb transducer to sweep in phase velocity and frequency space. It is demonstrated using guided interface waves for bond evaluation. After searching nearby mode points, an optimal mode and frequency can be selected which has the highest sensitivity to a defect, or gives the greatest penetration power. The optimal mode choice for a given application depends on the requirements of the inspection. Copyright © 2014 Elsevier B.V. All rights reserved.

Mode identification from spectroscopy of gravity-mode pulsators

NASA Astrophysics Data System (ADS)

Pollard, K. R.; Brunsden, E.; Cottrell, P. L.; Davie, M.; Greenwood, A.; Wright, D. J.; De Cat, P.

2014-02-01

The gravity modes present in γ Doradus stars probe the deep stellar interiors and are thus of particular interest in asteroseismology. For the MUSICIAN programme at the University of Canterbury, we obtain extensive high-resolution echelle spectra of γ Dor stars from the Mt John University Observatory in New Zealand. We analyze these to obtain the pulsational frequencies and identify these with the multiple pulsational modes excited in the star. A summary of recent results from our spectroscopic mode-identification programme is given.

Performance of an untethered micro-optical pressure sensor

NASA Astrophysics Data System (ADS)

Ioppolo, Tindaro; Manzo, Maurizio; Krueger, Paul

2012-11-01

We present analytical and computational studies of the performance of a novel untethered micro-optical pressure sensor for fluid dynamics measurements. In particular, resolution and dynamic range will be presented. The sensor concept is based on the whispering galley mode (WGM) shifts that are observed in micro-scale dielectric optical cavities. A micro-spherical optical cavity (liquid or solid) is embedded in a thin polymeric sheet. The applied external pressure perturbs the morphology of the optical cavity leading to a shift in its optical resonances. The optical sensors are interrogated remotely, by embedding quantum dots or fluorescent dye in the micro-optical cavity. This allows a free space coupling of excitation and monitoring of the optical modes without the need of optical fibers or other cabling. With appropriate excitation and monitoring equipment, the micro-scale sensors can be distributed over a surface (e.g., including flexible biological surfaces) to monitor the local pressure field. We acknowledge the financial support from the National Science Foundation through grant CBET-1133876 with Dr. Horst Henning Winter as the program director.

Shooting Gallery Operation in the Context of Establishing a Medically Supervised Injecting Center: Sydney, Australia

PubMed Central

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

Edge-localized mode avoidance and pedestal structure in I-mode plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to themore » structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs

Low-bending loss and single-mode operation in few-mode optical fiber

NASA Astrophysics Data System (ADS)

Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng

2016-10-01

The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.

Plasma Modes

NASA Astrophysics Data System (ADS)

Dubin, D. H. E.

This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

Coupling system to a microsphere cavity

NASA Technical Reports Server (NTRS)

Iltchenko, Vladimir (Inventor); Maleki, Lute (Inventor); Yao, Steve (Inventor); Wu, Chi (Inventor)

2002-01-01

A system of coupling optical energy in a waveguide mode, into a resonator that operates in a whispering gallery mode. A first part of the operation uses a fiber in its waveguide mode to couple information into a resonator e.g. a microsphere. The fiber is cleaved at an angle .PHI. which causes total internal reflection within the fiber. The energy in the fiber then forms an evanescent field and a microsphere is placed in the area of the evanescent field. If the microsphere resonance is resonant with energy in the fiber, then the information in the fiber is effectively transferred to the microsphere.

Stability and time-domain analysis of the dispersive tristability in microresonators under modal coupling

NASA Astrophysics Data System (ADS)

Dumeige, Yannick; Féron, Patrice

2011-10-01

Coupled nonlinear resonators have potential applications for the integration of multistable photonic devices. The dynamic properties of two coupled-mode nonlinear microcavities made of Kerr material are studied by linear stability analysis. Using a suitable combination of the modal coupling rate and the frequency detuning, it is possible to obtain configurations where a hysteresis loop is included inside other bistable cycles. We show that a single resonator with two modes both linearly and nonlinearly coupled via the cross-Kerr effect can have a multistable behavior. This could be implemented in semiconductor nonlinear whispering-gallery-mode microresonators under modal coupling for all optical signal processing or ternary optical logic applications.

Third order nonlinear phenomena in silica solid and hollow whispering gallery mode resonators

NASA Astrophysics Data System (ADS)

Farnesi, D.; Barucci, A.; Berneschi, S.; Cosi, F.; Righini, G. C.; Nunzi Conti, G.; Soria, Silvia

2016-03-01

We report efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility χ(3) interactions in resonant silica microspheres and microbubbles in the regime of normal dispersion. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS) and comb generation. Unusually strong anti-Stokes components and extraordinarily symmetric spectra have been observed. Resonant SARS and SRS corresponding to different Raman bands were also observed. The lack of correlation between stimulated anti-stokes and stokes scattering spectra indicates that the signal has to be resonant with the cavity.

4 × 20 Gbit/s mode division multiplexing over free space using vector modes and a q-plate mode (de)multiplexer

NASA Astrophysics Data System (ADS)

Milione, Giovanni; Lavery, Martin P. J.; Huang, Hao; Ren, Yongxiong; Xie, Guodong; Nguyen, Thien An; Karimi, Ebrahim; Marrucci, Lorenzo; Nolan, Daniel A.; Alfano, Robert R.; Willner, Alan E.

2015-05-01

Vector modes are spatial modes that have spatially inhomogeneous states of polarization, such as, radial and azimuthal polarization. They can produce smaller spot sizes and stronger longitudinal polarization components upon focusing. As a result, they are used for many applications, including optical trapping and nanoscale imaging. In this work, vector modes are used to increase the information capacity of free space optical communication via the method of optical communication referred to as mode division multiplexing. A mode (de)multiplexer for vector modes based on a liquid crystal technology referred to as a q-plate is introduced. As a proof of principle, using the mode (de)multiplexer four vector modes each carrying a 20 Gbit/s quadrature phase shift keying signal on a single wavelength channel (~1550nm), comprising an aggregate 80 Gbit/s, were transmitted ~1m over the lab table with <-16.4 dB (<2%) mode crosstalk. Bit error rates for all vector modes were measured at the forward error correction threshold with power penalties < 3.41dB.

Zinc oxide nanorod based photonic devices: recent progress in growth, light emitting diodes and lasers.

PubMed

Willander, M; Nur, O; Zhao, Q X; Yang, L L; Lorenz, M; Cao, B Q; Zúñiga Pérez, J; Czekalla, C; Zimmermann, G; Grundmann, M; Bakin, A; Behrends, A; Al-Suleiman, M; El-Shaer, A; Che Mofor, A; Postels, B; Waag, A; Boukos, N; Travlos, A; Kwack, H S; Guinard, J; Le Si Dang, D

2009-08-19

characteristics aimed at the development of white LEDs are demonstrated. Although some of the presented LEDs show visible emission for applied biases in excess of 10 V, optimized structures are expected to provide the same emission at much lower voltage. Finally, lasing from ZnO nanorods is briefly reviewed. An example of a recent whispering gallery mode (WGM) lasing from ZnO is demonstrated as a way to enhance the stimulated emission from small size structures.

Femtosecond pulse inscription of a selective mode filter in large mode area fibers

NASA Astrophysics Data System (ADS)

Krämer, Ria G.; Voigtländer, Christian; Freier, Erik; Liem, Andreas; Thomas, Jens U.; Richter, Daniel; Schreiber, Thomas; Tünnermann, Andreas; Nolte, Stefan

2013-02-01

We present a selective mode filter inscribed with ultrashort pulses directly into a few mode large mode area (LMA) fiber. The mode filter consists of two refractive index modifications alongside the fiber core in the cladding. The refractive index modifications, which were of approximately the same order of magnitude as the refractive index difference between core and cladding have been inscribed by nonlinear absorption of femtosecond laser pulses (800 nm wavelength, 120 fs pulse duration). If light is guided in the core, it will interact with the inscribed modifications causing modes to be coupled out of the core. In order to characterize the mode filter, we used a femtosecond inscribed fiber Bragg grating (FBG), which acts as a wavelength and therefore mode selective element in the LMA fiber. Since each mode has different Bragg reflection wavelengths, an FBG in a multimode fiber will exhibit multiple Bragg reflection peaks. In our experiments, we first inscribed the FBG using the phase mask scanning technique. Then the mode filter was inscribed. The reflection spectrum of the FBG was measured in situ during the inscription process using a supercontinuum source. The reflectivities of the LP01 and LP11 modes show a dependency on the length of the mode filter. Two stages of the filter were obtained: one, in which the LP11 mode was reduced by 60% and one where the LP01 mode was reduced by 80%. The other mode respectively showed almost no losses. In conclusion, we could selectively filter either the fundamental or higher order modes.

Second-harmonic generation in AlGaAs microdisks in the telecom range.

PubMed

Mariani, S; Andronico, A; Lemaître, A; Favero, I; Ducci, S; Leo, G

2014-05-15

We report on second-harmonic generation in whispering-gallery-mode AlGaAs microcavities suspended on a GaAs pedestal. Frequency doubling of a 1.58 μm pump is observed with 7×10(-4)   W(-1) conversion efficiency. This device can be integrated in a monolithic photonic chip for classical and quantum applications in the telecom band.

Damage initiation and propagation assessed from stress-induced microseismic events during a mine-by test in the Opalinus Clay

NASA Astrophysics Data System (ADS)

Le Gonidec, Y.; Sarout, J.; Wassermann, J.; Nussbaum, C.

2014-07-01

We report in this paper an original analysis of microseismic events (MSEs) induced by an excavation operation in the clay environment of the Mont Terri underground rock laboratory. In order to identify the MSEs with confidence, we develop a restrictive but efficient multistep method for filtering the recorded events. We deduce the spatial distribution and processes associated with the excavation-induced damage from the spatial location and focal mechanisms of the MSEs. We observe an asymmetric geometry of the excavation damaged zone around the excavated gallery, without notable microseismic activity in the sandy facies sidewall, in contrast with the shaly facies sidewall where a first burst of events is recorded, followed by two smaller bursts: one locates ahead of the excavation front and is associated with a dominant double-couple component, suggesting bedding plane reworking, that is, shear fracture mode, and the MSEs of the other cluster inside the shaly sidewall of the gallery, with a dominant compensated linear vector dipole component, suggesting extensive cracking. We identify and discuss four major factors that seem to control the MSEs source mechanisms: lithology, geometry of the geological features, gallery orientation and direction of the main compressive stress.

Inter-comb synchronization by mode-to-mode locking

NASA Astrophysics Data System (ADS)

Chun, Byung Jae; Kim, Young-Jin; Kim, Seung-Woo

2016-08-01

Two combs of fiber femtosecond lasers are synchronized through the optical frequency reference created by injection-locking of a diode laser to a single comb mode. Maintaining a mHz-level narrow linewidth, the optical frequency reference permits two combs to be stabilized by mode-to-mode locking with a relative stability of 1.52  ×  10-16 at 10 s with a frequency slip of 2.46 mHz. This inter-comb synchronization can be utilized for applications such as dual-comb spectroscopy or ultra-short pulse synthesis without extra narrow-linewidth lasers.

Design of elliptical-core mode-selective photonic lanterns with six modes for MIMO-free mode division multiplexing systems.

PubMed

Sai, Xiaowei; Li, Yan; Yang, Chen; Li, Wei; Qiu, Jifang; Hong, Xiaobin; Zuo, Yong; Guo, Hongxiang; Tong, Weijun; Wu, Jian

2017-11-01

Elliptical-core few mode fiber (EC-FMF) is used in a mode division multiplexing (MDM) transmission system to release multiple-input-multiple-output (MIMO) digital-signal-processing, which reduces the cost and the complexity of the receiver. However, EC-FMF does not match with conventional multiplexers/de-multiplexers (MUXs/DeMUXs) such as a photonic lantern, leading to extra mode coupling loss and crosstalk. We design elliptical-core mode-selective photonic lanterns (EC-MSPLs) with six modes, which can match well with EC-FMF in MIMO-free MDM systems. Simulation of the EC-MSPL using the beam propagation method was demonstrated employing a combination of either step-index or graded-index fibers with six different sizes of cores, and the taper transition length of 8 cm or 4 cm. Through numerical simulations and optimizations, both types of photonic lanterns can realize low loss transmission and low crosstalk of below -20.0  dB for all modes.

Mode-coupling theory

NASA Astrophysics Data System (ADS)

Reichman, David R.; Charbonneau, Patrick

2005-05-01

In this set of lecture notes we review the mode-coupling theory of the glass transition from several perspectives. First, we derive mode-coupling equations for the description of density fluctuations from microscopic considerations with the use the Mori Zwanzig projection operator technique. We also derive schematic mode-coupling equations of a similar form from a field-theoretic perspective. We review the successes and failures of mode-coupling theory, and discuss recent advances in the applications of the theory.

Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Guozhang; Xiang, Nong; Huang, Yueheng

2016-01-15

The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparablemore » to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ∼ 3ω{sub LH}, where ω{sub LH} represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ∼ 1.3ω{sub LH}), the generations of the high harmonic modes and sidebands through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.« less

Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

PubMed

Alcusa-Sáez, E; Díez, A; Andrés, M V

2016-03-07

Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP 01 and LP 1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.

Transient analysis mode participation for modal survey target mode selection using MSC/NASTRAN DMAP

NASA Technical Reports Server (NTRS)

Barnett, Alan R.; Ibrahim, Omar M.; Sullivan, Timothy L.; Goodnight, Thomas W.

1994-01-01

Many methods have been developed to aid analysts in identifying component modes which contribute significantly to component responses. These modes, typically targeted for dynamic model correlation via a modal survey, are known as target modes. Most methods used to identify target modes are based on component global dynamic behavior. It is sometimes unclear if these methods identify all modes contributing to responses important to the analyst. These responses are usually those in areas of hardware design concerns. One method used to check the completeness of target mode sets and identify modes contributing significantly to important component responses is mode participation. With this method, the participation of component modes in dynamic responses is quantified. Those modes which have high participation are likely modal survey target modes. Mode participation is most beneficial when it is used with responses from analyses simulating actual flight events. For spacecraft, these responses are generated via a structural dynamic coupled loads analysis. Using MSC/NASTRAN DMAP, a method has been developed for calculating mode participation based on transient coupled loads analysis results. The algorithm has been implemented to be compatible with an existing coupled loads methodology and has been used successfully to develop a set of modal survey target modes.

Determination of intrinsic mode and linear mode coupling in solar microwave bursts

NASA Astrophysics Data System (ADS)

Huang, Guangli; Song, Qiwu; Li, Jianping

2013-05-01

An explicit equation of the propagational angle of microwave emission between the line-of-sight and the local magnetic field is newly derived based on the approximated formulae of nonthermal gyrosynchrotron emission (Dulk and Marsh in Astrophys. J. 259, 350, 1982). The existence of the solution of propagational angle is clearly shown under a series of typical parameters in solar microwave observations. It could be used to determine the intrinsic mode and linear mode coupling in solar microwave bursts by three steps. (1) The mode coupling may happen only when the angle approximately equals to 90 degrees, i.e., when the emission propagates through the quasi-transverse region (Cohen in Astrophys. J. 131, 664, 1960). (2) The inversion of polarization sense due to the weakly mode coupling takes place only when the transition frequency defined by Cohen (1960) is larger than the frequency of microwave emission, and an observable criterion of the weakly mode coupling in flaring loops was indicated by the same polarization sense in the two footpoints of a flaring loop (Melrose and Robinson in Proc. Astron. Soc. Aust. 11, 16, 1994). (3) Finally, the intrinsic mode of microwave emission is determined by the observed polarization and the calculated direction of local magnetic field according to the general plasma dispersion relation, together with the mode coupling process. However, a 180-degree ambiguity still exists in the direction of longitudinal magnetic field, to produce an uncertainty of the intrinsic mode. One example is selected to check the feasibility of the method in the 2001 September 25 event with a loop-like structure nearby the central meridian passage observed by Nobeyama Radio Heliograph and Polarimeters. The calculated angle in one footpoint (FP) varied around 90∘ in two time intervals of the maximum phase, which gives a direct evidence of the emission propagating through a quasi-transverse region where the linear mode coupling took place, while, the angle

Dual-Mode Combustor

NASA Technical Reports Server (NTRS)

Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

2013-01-01

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

Zero-mode waveguides

DOEpatents

Levene, Michael J.; Korlach, Jonas; Turner, Stephen W.; Craighead, Harold G.; Webb, Watt W.

2007-02-20

The present invention is directed to a method and an apparatus for analysis of an analyte. The method involves providing a zero-mode waveguide which includes a cladding surrounding a core where the cladding is configured to preclude propagation of electromagnetic energy of a frequency less than a cutoff frequency longitudinally through the core of the zero-mode waveguide. The analyte is positioned in the core of the zero-mode waveguide and is then subjected, in the core of the zero-mode waveguide, to activating electromagnetic radiation of a frequency less than the cut-off frequency under conditions effective to permit analysis of the analyte in an effective observation volume which is more compact than if the analysis were carried out in the absence of the zero-mode waveguide.

Retrieving atmospheric turbulence information from regular commercial aircraft using Mode-S and ADS-B

NASA Astrophysics Data System (ADS)

Kopeć, Jacek M.; Kwiatkowski, Kamil; de Haan, Siebren; Malinowski, Szymon P.

2016-05-01

Navigational information broadcast by commercial aircraft in the form of Mode-S EHS (Mode-S Enhanced Surveillance) and ADS-B (Automatic Dependent Surveillance-Broadcast) messages can be considered a new source of upper tropospheric and lower stratospheric turbulence estimates. A set of three processing methods is proposed and analysed using a quality record of turbulence encounters made by a research aircraft.The proposed methods are based on processing the vertical acceleration or the background wind into the eddy dissipation rate. Turbulence intensity can be estimated using the standard content of the Mode-S EHS/ADS-B.The results are based on a Mode-S EHS/ADS-B data set generated synthetically based on the transmissions from the research aircraft. This data set was validated using the overlapping record of the Mode-S EHS/ADS-B received from the same research aircraft. The turbulence intensity, meaning the eddy dissipation rate, obtained from the proposed methods based on the Mode-S EHS/ADS-B is compared with the value obtained using on-board accelerometer. The results of the comparison indicate the potential of the methods. The advantages and limitation of the presented approaches are discussed.

Multiphoton endoscopy based on a mode-filtered single-mode fiber

NASA Astrophysics Data System (ADS)

Moon, Sucbei; Liu, Gangjun; Chen, Zhongping

2011-03-01

We present a new low-nonlinearity fiber of mode-filtered large-core fiber for flexible beam delivery of intense pulsed light aiming at multi-photon endoscopy application. A multimode fiber of a large core diameter (20 μm) equips a mode filtering means in the middle of the fiber link to suppress the high-order modes selectively. A large effective core area of ~200 μm2 has been achieved at 0.8-μm and 1.0-μm bands. This is 8 times larger than the core area of a conventional SMF used for those spectral bands. Various advantages of our large-mode area fiber will be demonstrated and discussed in this report.

Multi-mode radio frequency device

DOEpatents

Gilbert, Ronald W [Morgan Hill, CA; Carrender, Curtis Lee [Morgan Hill, CA; Anderson, Gordon A [Benton City, WA; Steele, Kerry D [Kennewick, WA

2007-02-13

A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

All-fiber-based selective mode multiplexer and demultiplexer for weakly-coupled mode-division multiplexed systems

NASA Astrophysics Data System (ADS)

Igarashi, Koji; Park, Kyung Jun; Tsuritani, Takahiro; Morita, Itsuro; Kim, Byoung Yoon

2018-02-01

We show all-fiber-based selective mode multiplexers and demultiplexers for weakly-coupled mode-division multiplexed systems. We fabricate a set of six-mode multiplexer and demultiplexer based on fiber mode selective couplers, and experimentally evaluate the performance for the six-mode dual-polarization (DP) quadrature phase shift keying (QPSK) optical signals. In the mode multiplexer and demultiplexer, the mode couplings between the lower three modes and the higher three modes are suppressed to be less than -20 dB, which enables us to apply partial 6 ×6 MIMO equalizers even for the six-mode demultiplexing. For the six-mode DP-QPSK signals, the penalty of optical signal-to-noise ratio by replacing the full 12 ×12MIMO to the partial 6 ×6 MIMO is suppressed by less than 1 dB.

Printable Silicon Nanomembranes for Solar-Powered, Bi-Directional Phased-Array-Antenna Communication System on Flexible Substrates

DTIC Science & Technology

2013-04-01

Identification (RFID), Large Area Flexible Displays, Electronic Paper, Bio - Sensors , Large Area Conformal and Flexible Antennas, Smart and Interactive Textiles...Lepeshkin, R. W. Boyd, C. Chase, and J. E. Fajardo, “An environmental sensor based on an integrated optical whispering gallery mode disk resonator ...Ubiquitous Sensor Networks (USN), Vehicle Clickers Readers, Real Time Locating Systems, Lighting, Photovoltaics etc. FA9550-11-C-0014 STTR Phase II

Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel

This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of themore » phenomenon is demonstrated.« less

Stability and time-domain analysis of the dispersive tristability in microresonators under modal coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumeige, Yannick; Feron, Patrice

Coupled nonlinear resonators have potential applications for the integration of multistable photonic devices. The dynamic properties of two coupled-mode nonlinear microcavities made of Kerr material are studied by linear stability analysis. Using a suitable combination of the modal coupling rate and the frequency detuning, it is possible to obtain configurations where a hysteresis loop is included inside other bistable cycles. We show that a single resonator with two modes both linearly and nonlinearly coupled via the cross-Kerr effect can have a multistable behavior. This could be implemented in semiconductor nonlinear whispering-gallery-mode microresonators under modal coupling for all optical signal processingmore » or ternary optical logic applications.« less

List mode multichannel analyzer

DOEpatents

Archer, Daniel E [Livermore, CA; Luke, S John [Pleasanton, CA; Mauger, G Joseph [Livermore, CA; Riot, Vincent J [Berkeley, CA; Knapp, David A [Livermore, CA

2007-08-07

A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

Partially coherent surface plasmon modes

NASA Astrophysics Data System (ADS)

Niconoff, G. M.; Vara, P. M.; Munoz-Lopez, J.; Juárez-Morales, J. C.; Carbajal-Dominguez, A.

2011-04-01

Elementary long-range plasmon modes are described assuming an exponential dependence of the refractive index in the neighbourhood of the interface dielectric-metal thin film. The study is performed using coupling mode theory. The interference between two long-range plasmon modes generated that way allows the synthesis of surface sinusoidal plasmon modes, which can be considered as completely coherent generalized plasmon modes. These sinusoidal plasmon modes are used for the synthesis of new partially coherent surface plasmon modes, which are obtained by means of an incoherent superposition of sinusoidal plasmon modes where the period of each one is considered as a random variable. The kinds of surface modes generated have an easily tuneable profile controlled by means of the probability density function associated to the period. We show that partially coherent plasmon modes have the remarkable property to control the length of propagation which is a notable feature respect to the completely coherent surface plasmon mode. The numerical simulation for sinusoidal, Bessel, Gaussian and Dark Hollow plasmon modes are presented.

Mode coupling in vortex beams

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil T.

2018-05-01

We examine the mode coupling in vortex beams. Mode coupling also known as the crosstalk takes place due to turbulent characteristics of the atmospheric communication medium. This way, the transmitted intrinsic mode of the vortex beam leaks power to other extrinsic modes, thus preventing the correct detection of the transmitted symbol which is usually encoded into the mode index or the orbital angular momentum state of the vortex beam. Here we investigate the normalized power mode coupling ratios of several types of vortex beams, namely, Gaussian vortex beam, Bessel Gaussian beam, hypergeometric Gaussian beam and Laguerre Gaussian beam. It is found that smaller mode numbers lead to less mode coupling. The same is partially observed for increasing source sizes. Comparing the vortex beams amongst themselves, it is seen that hypergeometric Gaussian beam is the one retaining the most power in intrinsic mode during propagation, but only at lowest mode index of unity. At higher mode indices this advantage passes over to the Gaussian vortex beam.

Propagating annular modes

NASA Astrophysics Data System (ADS)

Sheshadri, A.; Plumb, R. A.

2017-12-01

The leading "annular mode", defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability, appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. In the troposphere, the leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes propagating anomalies. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. These facts have implications for eddy feedback and the susceptibility of the mode to external perturbations. If one interprets the annular modes as the modes of the system, then simple theory predicts that the response to steady forcing will usually be dominated by AM1 (with the longest time scale). However, such arguments should really be applied to the true modes. Experiments with a simplified GCM show that climate response to perturbations do not necessarily have AM1 structures. Implications of these results for stratosphere-troposphere interactions are explored. The POP

Subcritical crack growth in soda-lime glass in combined mode I and mode II loading

NASA Technical Reports Server (NTRS)

Singh, Dileep; Shetty, Dinesh K.

1990-01-01

Subcritical crack growth under mixed-mode loading was studied in soda-lime glass. Pure mode I, combined mode I and mode II, and pure mode II loadings were achieved in precracked disk specimens by loading in diametral compression at selected angles with respect to the symmetric radial crack. Crack growth was monitored by measuring the resistance changes in a microcircuit grid consisting of parallel, electrically conducting grid lines deposited on the surface of the disk specimens by photolithography. Subcritical crack growth rates in pure mode I, pure mode II, and combined mode I and mode II loading could be described by an exponential relationship between crack growth rate and an effective crack driving force derived from a mode I-mode II fracture toughness envelope. The effective crack driving force was based on an empirical representation of the noncoplanar strain energy release rate. Stress intensities for kinked cracks were assessed using the method of caustics and an initial decrease and a subsequent increase in the subcritical crack growth rates of kinked cracks were shown to correlate with the variations of the mode I and the mode II stress intensities.

Signatures of single-photon interaction between two quantum dots located in different cavities of a weakly coupled double microdisk structure

NASA Astrophysics Data System (ADS)

Seyfferle, S.; Hargart, F.; Jetter, M.; Hu, E.; Michler, P.

2018-01-01

We report on the radiative interaction of two single quantum dots (QDs) each in a separate InP/GaInP-based microdisk cavity via resonant whispering gallery modes. The investigations are based on as-fabricated coupled disk modes. We apply optical spectroscopy involving a 4 f setup, as well as mode-selective real-space imaging and photoluminescence mapping to discern single QDs coupled to a resonant microdisk mode. Excitation of one disk of the double cavity structure and detecting photoluminescence from the other yields proof of single-photon emission of a QD excited by incoherent energy transfer from one disk to the other via a mode in the weak-coupling regime. Finally, we present evidence of photons emitted by a QD in one disk that are transferred to the other disk by a resonant mode and are subsequently resonantly scattered by another QD.

ToF-SIMS Depth Profiling Of Insulating Samples, Interlaced Mode Or Non-interlaced Mode?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhaoying; Jin, Ke; Zhang, Yanwen

2014-11-01

Dual beam depth profiling strategy has been widely adopted in ToF-SIMS depth profiling, in which two basic operation modes, interlaced mode and non-interlaced mode, are commonly used. Generally, interlaced mode is recommended for conductive or semi-conductive samples, whereas non-interlaced mode is recommended for insulating samples, where charge compensation can be an issue. Recent publications, however, show that the interlaced mode can be used effectively for glass depth profiling, despite the fact that glass is an insulator. In this study, we provide a simple guide for choosing between interlaced mode and non-interlaced mode for insulator depth profiling. Two representative cases aremore » presented: (1) depth profiling of a leached glass sample, and (2) depth profiling of a single crystal MgO sample. In brief, the interlaced mode should be attempted first, because (1) it may provide reasonable-quality data, and (2) it is time-saving for most cases, and (3) it introduces low H/C/O background. If data quality is the top priority and measurement time is flexible, non-interlaced mode is recommended because interlaced mode may suffer from low signal intensity and poor mass resolution. A big challenge is tracking trace H/C/O in a highly insulating sample (e.g., MgO), because non-interlaced mode may introduce strong H/C/O background but interlaced mode may suffer from low signal intensity. Meanwhile, a C or Au coating is found to be very effective to improve the signal intensity. Surprisingly, the best analyzing location is not on the C or Au coating, but at the edge (outside) of the coating.« less

Mode conversion efficiency to Laguerre-Gaussian OAM modes using spiral phase optics.

PubMed

Longman, Andrew; Fedosejevs, Robert

2017-07-24

An analytical model for the conversion efficiency from a TEM 00 mode to an arbitrary Laguerre-Gaussian (LG) mode with null radial index spiral phase optics is presented. We extend this model to include the effects of stepped spiral phase optics, spiral phase optics of non-integer topological charge, and the reduction in conversion efficiency due to broad laser bandwidth. We find that through optimization, an optimal beam waist ratio of the input and output modes exists and is dependent upon the output azimuthal mode number.

Slow crack growth in glass in combined mode I and mode II loading

NASA Technical Reports Server (NTRS)

Shetty, D. K.; Rosenfield, A. R.

1991-01-01

Slow crack growth in soda-lime glass under combined mode I and mode II loading was investigated in precracked disk specimens in which pure mode I, pure mode II, and various combinations of mode I and mode II were achieved by loading in diametral compression at selected angles with respect to symmetric radial cracks. It is shown that slow crack growth under these conditions can be described by a simple exponential relationship with elastic strain energy release rate as the effective crack-driving force parameter. It is possible to interpret this equation in terms of theoretical models that treat subcritical crack growth as a thermally activated bond-rupture process with an activation energy dependent on the environment, and the elastic energy release rate as the crack-driving force parameter.

Comparison of detectability in step-and-shoot mode and continuous mode digital tomosynthesis systems

NASA Astrophysics Data System (ADS)

Lee, Changwoo; Han, Minah; Baek, Jongduk

2017-03-01

Digital tomosynthesis system has been widely used in chest, dental, and breast imaging. Since the digital tomosynthesis system provides volumetric images from multiple projection data, structural noise inherent in X-ray radiograph can be reduced, and thus signal detection performance is improved. Currently, tomosynthesis system uses two data acquisition modes: step-and-shoot mode and continuous mode. Several studies have been conducted to compare the system performance of two acquisition modes with respect to spatial resolution and contrast. In this work, we focus on signal detectability in step-and-shoot mode and continuous mode. For evaluation, uniform background is considered, and eight spherical objects with diameters of 0.5, 0.8, 1, 2, 3, 5, 8, 10 mm are used as signals. Projection data with and without spherical objects are acquired in step-and-shoot mode and continuous mode, respectively, and quantum noise are added. Then, noisy projection data are reconstructed by FDK algorithm. To compare the detection performance of two acquisition modes, we calculate task signal-to-noise ratio (SNR) of channelized Hotelling observer with Laguerre-Gauss channels for each spherical object. While the task-SNR values of two acquisition modes are similar for spherical objects larger than 1 mm diameter, step-and-shoot mode yields higher detectability for small signal sizes. The main reason of this behavior is that small signal is more affected by X-ray tube motion blur than large signal. Our results indicate that it is beneficial to use step-and-shoot data acquisition mode to improve the detectability of small signals (i.e., less than 1 mm diameter) in digital tomosynthesis systems.

Processing mode during repetitive thinking in socially anxious individuals: evidence for a maladaptive experiential mode.

PubMed

Wong, Quincy J J; Moulds, Michelle L

2012-12-01

Evidence from the depression literature suggests that an analytical processing mode adopted during repetitive thinking leads to maladaptive outcomes relative to an experiential processing mode. To date, in socially anxious individuals, the impact of processing mode during repetitive thinking related to an actual social-evaluative situation has not been investigated. We thus tested whether an analytical processing mode would be maladaptive relative to an experiential processing mode during anticipatory processing and post-event rumination. High and low socially anxious participants were induced to engage in either an analytical or experiential processing mode during: (a) anticipatory processing before performing a speech (Experiment 1; N = 94), or (b) post-event rumination after performing a speech (Experiment 2; N = 74). Mood, cognition, and behavioural measures were employed to examine the effects of processing mode. For high socially anxious participants, the modes had a similar effect on self-reported anxiety during both anticipatory processing and post-event rumination. Unexpectedly, relative to the analytical mode, the experiential mode led to stronger high standard and conditional beliefs during anticipatory processing, and stronger unconditional beliefs during post-event rumination. These experiments are the first to investigate processing mode during anticipatory processing and post-event rumination. Hence, these results are novel and will need to be replicated. These findings suggest that an experiential processing mode is maladaptive relative to an analytical processing mode during repetitive thinking characteristic of socially anxious individuals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pad-mode-induced instantaneous mode instability for simple models of brake systems

NASA Astrophysics Data System (ADS)

Oberst, S.; Lai, J. C. S.

2015-10-01

Automotive disc brake squeal is fugitive, transient and remains difficult to predict. In particular, instantaneous mode squeal observed experimentally does not seem to be associated with mode coupling and its mechanism is not clear. The effects of contact pressures, friction coefficients as well as material properties (pressure and temperature dependency and anisotropy) for brake squeal propensity have not been systematically explored. By analysing a finite element model of an isotropic pad sliding on a plate similar to that of a previously reported experimental study, pad modes have been identified and found to be stable using conventional complex eigenvalue analysis. However, by subjecting the model to contact pressure harmonic excitation for a range of pressures and friction coefficients, a forced response analysis reveals that the dissipated energy for pad modes is negative and becomes more negative with increasing contact pressures and friction coefficients, indicating the potential for instabilities. The frequency of the pad mode in the sliding direction is within the range of squeal frequencies observed experimentally. Nonlinear time series analysis of the vibration velocity also confirms the evolution of instabilities induced by pad modes as the friction coefficient increases. By extending this analysis to a more realistic but simple brake model in the form of a pad-on-disc system, in-plane pad-modes, which a complex eigenvalue analysis predicts to be stable, have also been identified by negative dissipated energy for both isotropic and anisotropic pad material properties. The influence of contact pressures on potential instabilities has been found to be more dominant than changes in material properties owing to changes in pressure or temperature. Results here suggest that instantaneous mode squeal is likely caused by in-plane pad-mode instabilities.

The Integrated Mode Management Interface

NASA Technical Reports Server (NTRS)

Hutchins, Edwin

1996-01-01

Mode management is the processes of understanding the character and consequences of autoflight modes, planning and selecting the engagement, disengagement and transitions between modes, and anticipating automatic mode transitions made by the autoflight system itself. The state of the art is represented by the latest designs produced by each of the major airframe manufacturers, the Boeing 747-400, the Boeing 777, the McDonnell Douglas MD-11, and the Airbus A320/A340 family of airplanes. In these airplanes autoflight modes are selected by manipulating switches on the control panel. The state of the autoflight system is displayed on the flight mode annunciators. The integrated mode management interface (IMMI) is a graphical interface to autoflight mode management systems for aircraft equipped with flight management computer systems (FMCS). The interface consists of a vertical mode manager and a lateral mode manager. Autoflight modes are depicted by icons on a graphical display. Mode selection is accomplished by touching (or mousing) the appropriate icon. The IMMI provides flight crews with an integrated interface to autoflight systems for aircraft equipped with flight management computer systems (FMCS). The current version is modeled on the Boeing glass-cockpit airplanes (747-400, 757/767). It runs on the SGI Indigo workstation. A working prototype of this graphics-based crew interface to the autoflight mode management tasks of glass cockpit airplanes has been installed in the Advanced Concepts Flight Simulator of the CSSRF of NASA Ames Research Center. This IMMI replaces the devices in FMCS equipped airplanes currently known as mode control panel (Boeing), flight guidance control panel (McDonnell Douglas), and flight control unit (Airbus). It also augments the functions of the flight mode annunciators. All glass cockpit airplanes are sufficiently similar that the IMMI could be tailored to the mode management system of any modern cockpit. The IMMI does not replace the

Relating normal vibrational modes to local vibrational modes with the help of an adiabatic connection scheme

NASA Astrophysics Data System (ADS)

Zou, Wenli; Kalescky, Robert; Kraka, Elfi; Cremer, Dieter

2012-08-01

Information on the electronic structure of a molecule and its chemical bonds is encoded in the molecular normal vibrational modes. However, normal vibrational modes result from a coupling of local vibrational modes, which means that only the latter can provide detailed insight into bonding and other structural features. In this work, it is proven that the adiabatic internal coordinate vibrational modes of Konkoli and Cremer [Int. J. Quantum Chem. 67, 29 (1998)], 10.1002/(SICI)1097-461X(1998)67:1<29::AID-QUA3>3.0.CO;2-0 represent a unique set of local modes that is directly related to the normal vibrational modes. The missing link between these two sets of modes are the compliance constants of Decius, which turn out to be the reciprocals of the local mode force constants of Konkoli and Cremer. Using the compliance constants matrix, the local mode frequencies of any molecule can be converted into its normal mode frequencies with the help of an adiabatic connection scheme that defines the coupling of the local modes in terms of coupling frequencies and reveals how avoided crossings between the local modes lead to changes in the character of the normal modes.

Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Yu, Nam; Thompson, Robert J.

2012-01-01

The most accurate astronomical data is available from space-based observations that are not impeded by the Earth's atmosphere. Such measurements may require spectral samples taken as long as decades apart, with the 1 cm/s velocity precision integrated over a broad wavelength range. This raises the requirements specifically for instruments used in astrophysics research missions -- their stringent wavelength resolution and accuracy must be maintained over years and possibly decades. Therefore, a stable and broadband optical calibration technique compatible with spaceflights becomes essential. The space-based spectroscopic instruments need to be calibrated in situ, which puts forth specific requirements to the calibration sources, mainly concerned with their mass, power consumption, and reliability. A high-precision, high-resolution reference wavelength comb source for astronomical and astrophysics spectroscopic observations has been developed that is deployable in space. The optical comb will be used for wavelength calibrations of spectrographs and will enable Doppler measurements to better than 10 cm/s precision, one hundred times better than the current state-of-the- art.

Coupling analysis of non-circular-symmetric modes and design of orientation-insensitive few-mode fiber couplers

NASA Astrophysics Data System (ADS)

Li, Jiaxiong; Du, Jiangbing; Ma, Lin; Li, Ming-Jun; Jiang, Shoulin; Xu, Xiao; He, Zuyuan

2017-01-01

We study the coupling between two identical weakly-coupled few-mode fibers based on coupled-mode theory. The coupling behavior of non-circular-symmetric modes, such as LP11 and LP21, is investigated analytically and numerically. By carefully choosing the fiber core separation and coupler length, we can design orientation-insensitive fiber couplers for non-circular-symmetric modes at arbitrary coupling ratios. Based on the design method, we propose an orientation-insensitive two-mode fiber coupler at 850 nm working as a mode multiplexer/demultiplexer for two-mode transmission using standard single-mode fiber. Within the band from 845 to 855 nm, the insertion losses of LP01 and LP11 modes are less than 0.03 dB and 0.24 dB, respectively. When the two-mode fiber coupler is used as mode demultiplexer, the LP01/LP11 and LP11/LP01 extinction ratios in the separated branches are respectively above 12.6 dB and 21.2 dB. Our design method can be extended to two-mode communication or sensing systems at other wavelengths.

Moving target detection in flash mode against stroboscopic mode by active range-gated laser imaging

NASA Astrophysics Data System (ADS)

Zhang, Xuanyu; Wang, Xinwei; Sun, Liang; Fan, Songtao; Lei, Pingshun; Zhou, Yan; Liu, Yuliang

2018-01-01

Moving target detection is important for the application of target tracking and remote surveillance in active range-gated laser imaging. This technique has two operation modes based on the difference of the number of pulses per frame: stroboscopic mode with the accumulation of multiple laser pulses per frame and flash mode with a single shot of laser pulse per frame. In this paper, we have established a range-gated laser imaging system. In the system, two types of lasers with different frequency were chosen for the two modes. Electric fan and horizontal sliding track were selected as the moving targets to compare the moving blurring between two modes. Consequently, the system working in flash mode shows more excellent performance in motion blurring against stroboscopic mode. Furthermore, based on experiments and theoretical analysis, we presented the higher signal-to-noise ratio of image acquired by stroboscopic mode than flash mode in indoor and underwater environment.

Synergetic scattering of SiO2 and Ag nanoparticles for light-trapping enhancement in organic bulk heterojunction

NASA Astrophysics Data System (ADS)

Yang, Huan; Ding, Qiuyu; Li, Ben Q.; Jiang, Xinbing; Zhang, Manman

2018-02-01

Though noble metal nanoparticles have been explored to enhance the performance of the organic solar cell, effect of dielectric nanoparticles, and coupled effect of dielectric and metal nanoparticles, have rarely been reported, if at all, on organic solar cell. This work reports an experimental study on synergetic scattering of SiO2 and Ag nanoparticles in a bulk organic heterojunction for the broadband light absorption enhancement. The wavelength scale SiO2 particles were arranged as a monolayer on the surface of the solar cell to guide incident light into the active layer and prolong the effective optical length of the entered energy. This is achieved by the excitation of whispering gallery modes in SiO2 nanoparticles and by leaky mode radiation. When small size Ag particles were incorporated into the transport layer of the solar cell, synergetic scattering of SiO2 and Ag nanoparticles is formed by coupling of the whispering gallery mode of closely arranged SiO2 particles atop and collaborative localized surface plasma resonance scattering of Ag nanoparticles dispersed in the transport layer. As a result, the performance of the organic solar cell is greatly enhanced and the short-circuit current density has an improvement of 42.47%. Therefore, the organic solar cell incorporated with SiO2 and Ag particles presents a meaningful strategy to achieve high energy-harvesting performance. [Figure not available: see fulltext.

The Aerosol Coarse Mode Initiative

NASA Astrophysics Data System (ADS)

Arnott, W. P.; Adhikari, N.; Air, D.; Kassianov, E.; Barnard, J.

2014-12-01

Many areas of the world show an aerosol volume distribution with a significant coarse mode and sometimes a dominant coarse mode. The large coarse mode is usually due to dust, but sea salt aerosol can also play an important role. However, in many field campaigns, the coarse mode tends to be ignored, because it is difficult to measure. This lack of measurements leads directly to a concomitant "lack of analysis" of this mode. Because, coarse mode aerosols can have significant effects on radiative forcing, both in the shortwave and longwave spectrum, the coarse mode -- and these forcings -- should be accounted for in atmospheric models. Forcings based only on fine mode aerosols have the potential to be misleading. In this paper we describe examples of large coarse modes that occur in areas of large aerosol loading (Mexico City, Barnard et al., 2010) as well as small loadings (Sacramento, CA; Kassianov et al., 2012; and Reno, NV). We then demonstrate that: (1) the coarse mode can contribute significantly to radiative forcing, relative to the fine mode, and (2) neglecting the coarse mode may result in poor comparisons between measurements and models. Next we describe -- in general terms -- the limitations of instrumentation to measure the coarse mode. Finally, we suggest a new initiative aimed at examining coarse mode aerosol generation mechanisms; transport and deposition; chemical composition; visible and thermal IR refractive indices; morphology; microphysical behavior when deposited on snow and ice; and specific instrumentation needs. Barnard, J. C., J. D. Fast, G. Paredes-Miranda, W. P. Arnott, and A. Laskin, 2010: Technical Note: Evaluation of the WRF-Chem "Aerosol Chemical to Aerosol Optical Properties" Module using data from the MILAGRO campaign, Atmospheric Chemistry and Physics, 10, 7325-7340. Kassianov, E. I., M. S. Pekour, and J. C. Barnard, 2012: Aerosols in Central California: Unexpectedly large contribution of coarse mode to aerosol radiative forcing

Probing plasmonic breathing modes optically

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krug, Markus K., E-mail: markus.krug@uni-graz.at; Reisecker, Michael; Hohenau, Andreas

2014-10-27

The confinement of surface plasmon modes in flat nanoparticles gives rise to plasmonic breathing modes. With a vanishing net dipole moment, breathing modes do not radiate, i.e., they are optically dark. Having thus escaped optical detection, breathing modes were only recently revealed in silver nanodisks with electron energy loss spectroscopy in an electron microscope. We show that for disk diameters >200 nm, retardation induced by oblique optical illumination relaxes the optically dark character. This makes breathing modes and thus the full plasmonic mode spectrum accessible to optical spectroscopy. The experimental spectroscopy data are in excellent agreement with numerical simulations.

Autumnal resorption and accretion of trace metals in gallery forest tree. [Quercus macrocarpa, Quercus muehlenbergii, Fraxinus pennsylvanica, Celtis occidentalis, and Ulmus rubra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Killingbeck, K.T.

1985-02-01

Autumnal resorption and accretion of copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) were measured in the foliage of five gallery forest trees species on the Konza Prairie Research Natural Area. Presenescence and postabscission leaves from five trees each of Quercus macrocarpa, Q. muehlenbergii, Fraxinus pennsylvanica, Celtis occidentalis, and Ulmus rubra, were sampled. Three species resorbed 19, 25, and 26%, respectively, of their presenescence foliar Zn, and one species resorbed 35% of its presenescence foliar Fe. This validates the prediction made by others that Zn and Fe are withdrawn from the senescing foliage of at least some deciduous species.more » Net accretions of Cu (43, 44, 69%), Fe (36, 40%), and Mn (19, 57%) occurred during the same period. The two oak species were responsible for most of the resorption, while the three non-oak species accounted for all of the significant accretions. Such well-defined differences in element conservation may influence interspecific competition by accentuating, or compensating for, species differences in element uptake ability and element use efficiency. Demand:availability ratios proved useful in predicting the likelihood that a given element would be conserved through resorption.« less

Microstructural effects on fracture toughness of polycrystalline ceramics in combined mode I and mode II loading

NASA Technical Reports Server (NTRS)

Singh, D.; Shetty, D. K.

1988-01-01

Fracture toughness of polycrystalline alumina and ceria partially-stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion was the main source of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.

Nonlinear interaction in differential mode delay managed mode-division multiplexed transmission systems.

PubMed

Rademacher, Georg; Warm, Stefan; Petermann, Klaus

2015-01-12

We analyze the impact of Differential Mode Delay (DMD) Management on the nonlinear impairments in mode-division multiplexed transmission systems. It is found out that DMD Management can lead to a degraded performance, due to enhanced intermodal nonlinear interaction. This can be attributed to an increased correlation of co-propagating channels, similar to the effects that show up in dispersion managed single-mode systems.

Extending Mode Areas of Single-mode All-solid Photonic Bandgap Fibers

DTIC Science & Technology

2015-04-02

T. Tunnermann, R. Iliew, F. Lederer, J. Broeng, G. Vienne, A. Petersson, and C. Jakobsen, “High-power air-clad large-mode-area photonic crystal ...Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 (2006). 10. L. Dong, T. Wu, H. McKay, L. Fu...progress in mode area scaling of optical fibers. One notable area is in photonic crystal fibers (PCF) [3–5, 8, 9]. The short straight PCF rods used in

Cavity optomechanics in a levitated helium drop

NASA Astrophysics Data System (ADS)

Childress, L.; Schmidt, M. P.; Kashkanova, A. D.; Brown, C. D.; Harris, G. I.; Aiello, A.; Marquardt, F.; Harris, J. G. E.

2017-12-01

We describe a proposal for a type of optomechanical system based on a drop of liquid helium that is magnetically levitated in vacuum. In the proposed device, the drop would serve three roles: its optical whispering-gallery modes would provide the optical cavity, its surface vibrations would constitute the mechanical element, and evaporation of He atoms from its surface would provide continuous refrigeration. We analyze the feasibility of such a system in light of previous experimental demonstrations of its essential components: magnetic levitation of mm-scale and cm-scale drops of liquid He , evaporative cooling of He droplets in vacuum, and coupling to high-quality optical whispering-gallery modes in a wide range of liquids. We find that the combination of these features could result in a device that approaches the single-photon strong-coupling regime, due to the high optical quality factors attainable at low temperatures. Moreover, the system offers a unique opportunity to use optical techniques to study the motion of a superfluid that is freely levitating in vacuum (in the case of 4He). Alternatively, for a normal fluid drop of 3He, we propose to exploit the coupling between the drop's rotations and vibrations to perform quantum nondemolition measurements of angular momentum.

Normal modes and mode transformation of pure electron vortex beams

PubMed Central

Thirunavukkarasu, G.; Mousley, M.; Babiker, M.

2017-01-01

Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre–Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite–Gaussian beams. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069769

Normal modes and mode transformation of pure electron vortex beams.

PubMed

Thirunavukkarasu, G; Mousley, M; Babiker, M; Yuan, J

2017-02-28

Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre-Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite-Gaussian beams.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

Frequency regularities of acoustic modes and multi-colour mode identification in rapidly rotating stars

NASA Astrophysics Data System (ADS)

Reese, D. R.; Lignières, F.; Ballot, J.; Dupret, M.-A.; Barban, C.; van't Veer-Menneret, C.; MacGregor, K. B.

2017-05-01

Context. Mode identification has remained a major obstacle in the interpretation of pulsation spectra in rapidly rotating stars. This has motivated recent work on calculating realistic multi-colour mode visibilities in this type of star. Aims: We would like to test mode identification methods and seismic diagnostics in rapidly rotating stars, using oscillation spectra that are based on these new theoretical predictions. Methods: We investigate the auto-correlation function and Fourier transform of theoretically calculated frequency spectra, in which modes are selected according to their visibilities. Given that intrinsic mode amplitudes are determined by non-linear saturation and cannot currently be theoretically predicted, we experimented with various ad-hoc prescriptions for setting the mode amplitudes, including using random values. Furthermore, we analyse the ratios between mode amplitudes observed in different photometric bands to see up to what extent they can identify modes. Results: When non-random intrinsic mode amplitudes are used, our results show that it is possible to extract a mean value for the large frequency separation or half its value and, sometimes, twice the rotation rate, from the auto-correlation of the frequency spectra. Furthermore, the Fourier transforms are mostly sensitive to the large frequency separation or half its value. The combination of the two methods may therefore measure and distinguish the two types of separations. When the intrinsic mode amplitudes include random factors, which seems more representative of real stars, the results are far less favourable. It is only when the large separation or half its value coincides with twice the rotation rate, that it might be possible to detect the signature of a frequency regularity. We also find that amplitude ratios are a good way of grouping together modes with similar characteristics. By analysing the frequencies of these groups, it is possible to constrain mode identification, as

Failure mode and effects analysis: an empirical comparison of failure mode scoring procedures.

PubMed

Ashley, Laura; Armitage, Gerry

2010-12-01

To empirically compare 2 different commonly used failure mode and effects analysis (FMEA) scoring procedures with respect to their resultant failure mode scores and prioritization: a mathematical procedure, where scores are assigned independently by FMEA team members and averaged, and a consensus procedure, where scores are agreed on by the FMEA team via discussion. A multidisciplinary team undertook a Healthcare FMEA of chemotherapy administration. This included mapping the chemotherapy process, identifying and scoring failure modes (potential errors) for each process step, and generating remedial strategies to counteract them. Failure modes were scored using both an independent mathematical procedure and a team consensus procedure. Almost three-fifths of the 30 failure modes generated were scored differently by the 2 procedures, and for just more than one-third of cases, the score discrepancy was substantial. Using the Healthcare FMEA prioritization cutoff score, almost twice as many failure modes were prioritized by the consensus procedure than by the mathematical procedure. This is the first study to empirically demonstrate that different FMEA scoring procedures can score and prioritize failure modes differently. It found considerable variability in individual team members' opinions on scores, which highlights the subjective and qualitative nature of failure mode scoring. A consensus scoring procedure may be most appropriate for FMEA as it allows variability in individuals' scores and rationales to become apparent and to be discussed and resolved by the team. It may also yield team learning and communication benefits unlikely to result from a mathematical procedure.

Dual-LP11 mode 4×4 MIMO-OFDM transmission over a two-mode fiber.

PubMed

Al Amin, Abdullah; Li, An; Chen, Simin; Chen, Xi; Gao, Guanjun; Shieh, William

2011-08-15

We report successful transmission of dual-LP(11) mode (LP(11a) and LP(11b)), dual polarization coherent optical orthogonal frequency-division multiplexing (CO-OFDM) signals over two-mode fibers (TMF) using all-fiber mode converters. Mode converters based on mechanically induced long-period grating with better than 20 dB extinction ratios are realized and used for interfacing single-mode fiber transmitter and receivers to the TMF. We demonstrate that by using 4×4 MIMO-OFDM processing, the random coupling of the two LP(11) spatial modes can be successfully tracked and equalized with a one-tap frequency-domain equalizer. We achieve successful transmission of 35.3 Gb/s over 26-km two-mode fiber with less than 3 dB penalty. © 2011 Optical Society of America

Mode I, Mode II, and Mixed-Mode Fracture of Plasma-sprayed Thermal Barrier Coatings at Ambient and Elevated Temperatures

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Zhu, Dongming; Miller, Robert A.

2003-01-01

The mixed-mode fracture behavior of plasma-sprayed ZrO2-8 wt% Y2O3 thermal barrier coatings was determined in air at 25 and 1316 C in asymmetric four-point flexure with single edge v-notched beam (SEVNB) test specimens. The mode I fracture toughness was found to be K(sub Ic) = 1.15 plus or minus 0.07 and 0.98 plus or minus 0.13 MPa the square root of m, respectively, at 25 and 1316 C. The respective mode II fracture toughness values were K(sub IIc) = 0.73 plus or minus 0.10 and 0.65 plus or minus 0.04 MPa the square root of m. Hence, there was an insignificant difference in either K(sub Ic or K(sub IIc) between 25 and 1316 C for the coating material, whereas there was a noticeable distinction between K(sub Ic) and K(sub IIc), resulting in K(sub IIc) per K(sub Ic) = 0.65 at both temperatures. The empirical mixed-mode fracture criterion best described the coatings' mixed-mode fracture behavior among the four mixed-mode fracture theories considered. The angle of crack propagation was in reasonable agreement with the minimum strain energy density criterion. The effect of the directionality of the coating material in on K(sub Ic) was observed to be insignificant, while its sintering effect at 1316 C on K(sub Ic) was significant.