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Sample records for high quality microcavities

  1. A high quality factor photonic crystal channel-drop filter with a linear gradient microcavity

    NASA Astrophysics Data System (ADS)

    Li, Chuan-qi; Fan, Qing-bin; Lu, Ye; Luo, De-jun; Kong, Yi-bu; Zhang, Dong-chuang

    2015-05-01

    We design a channel-drop filter (CDF) with a linear gradient microcavity in a two-dimensional (2D) photonic crystal (PC). The model of three-port CDF with reflector is used to achieve high quality factor (Q-factor) and 100% channel-drop efficiency. The research indicates that adjusting the distance between reference plane and reflector can simultaneously influence the Q-factor due to coupling to a bus waveguide and the phase retardation occurring in the round trip between a microcavity and a reflector. The calculation results of 2D finite-difference time-domain (FDTD) method show that the designed filter can achieve the drop efficiency of 96.7% and ultra-high Q-factor with an ultra-small modal volume.

  2. Optically induced mode splitting in self-assembled, high quality-factor conjugated polymer microcavities

    PubMed Central

    Braam, Daniel; Kushida, Soh; Niemöller, Robert; Prinz, Günther M.; Saito, Hitoshi; Kanbara, Takaki; Kuwabara, Junpei; Yamamoto, Yohei; Lorke, Axel

    2016-01-01

    We investigate the whispering gallery modes (WGMs) of self-assembled single microspheres. They consist of a recently developed highly fluorescent π-conjugated copolymer and exhibit excellent optical properties with Q-factors up to 104. Under continuous laser irradiation, we observe a splitting of the highly degenerate spherical WGMs into a multiplet of lines. Comparison with the calculated spectral response of a weakly distorted sphere shows that the optical excitation induces a change of the optical path length in the microcavity so that it resembles a prolate spheroid. The separation of the lines is given by the ellipticity and the azimuthal mode number. Measurements in various gaseous environments suggest that the distortion is caused by light induced oxidation of the polymer. Our findings show that photooxidation can be a beneficial mechanism for in-situ tuning of optically active polymer structures. PMID:26781838

  3. Design and optimizations of quasiperiodic microcavity with high-quality factor and its application in quantum dot lasers

    NASA Astrophysics Data System (ADS)

    Mosallanezhad, Gholamreza; Keshavarz, Alireza

    2015-10-01

    We propose an optimized quasiperiodic microcavity with the aim of achieving the highest quality factor. The proposed structure consists of two quasicrystal rings with different geometries. By performing several optimizations on the structure, the highest quality factor of 8.16×107 for a femtosecond laser with a wavelength of 1040 nm can be achieved. The quasiperiodic microcavity is used for a quantum dot laser application that obtained the highest output power of 3800 W/m2. The most important characteristics of this structure are the improvement of the quality factor and a simultaneously stable cavity wavelength.

  4. Hysteresis behavior of Kerr frequency comb generation in a high-quality-factor whispering-gallery-mode microcavity

    NASA Astrophysics Data System (ADS)

    Kato, Takumi; Chen-Jinnai, Akitoshi; Nagano, Takuma; Kobatake, Tomoya; Suzuki, Ryo; Yoshiki, Wataru; Tanabe, Takasumi

    2016-07-01

    A numerical and experimental study of Kerr frequency comb generation in a silica toroid microcavity is presented. We use a generalized mean-field Lugiato–Lefever equation and solve it with the split-step Fourier method. We observe that a stable mode-locked regime can be accessed when we reduce the input power after strong pumping due to the bistable nature of the nonlinear cavity system used. The experimental results agree well with the results of the numerical analysis, where we obtain a low-noise Kerr comb spectrum by gradually reducing the pumping input after strong pumping. This finding complements the results obtained by a previous wavelength scanning method and clarifies the procedure for achieving mode-locked states in such high-Q microcavity systems.

  5. Quality factor control in a lasing microcavity model

    PubMed

    Triandaf; Schwartz

    2000-04-01

    We consider a dynamics model of lasing microcavities, a class of optical resonators (1-10 &mgr;m in diameter) used in microlasers and for optical coupling of optical fibers. Inside such a cavity light circulates around the perimeter and is trapped by internal reflection. This is known as "whispering gallery" or high-Q modes. The cavity is a deformable cylindrical (or spherical) dielectric and at certain deformations light can escape by refraction. The quality of the resonator or Q factor, is defined as Q=omegatau, where tau is the escape time and omega is the frequency of light. We show that by appropriately deforming the cavity, the Q factor can be controlled by prolonging or shortening the average length of time spent by light trajectories inside the cavity. PMID:11088138

  6. High-temperature ultrafast polariton parametric amplification in semiconductor microcavities.

    PubMed

    Saba, M; Ciuti, C; Bloch, J; Thierry-Mieg, V; André, R; Dang, le S; Kundermann, S; Mura, A; Bongiovanni, G; Staehli, J L; Deveaud, B

    2001-12-13

    Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons. Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures. Here we demonstrate polariton parametric amplification up to 120 K in GaAlAs-based microcavities and up to 220 K in CdTe-based microcavities. We show that the cut-off temperature for the amplification is ultimately determined by the binding energy of the exciton. A 5-micrometer-thick planar microcavity can amplify a weak light pulse more than 5,000 times. The effective gain coefficient of an equivalent homogeneous medium would be 107 cm-1. The subpicosecond duration and high efficiency of the amplification could be exploited for high-repetition all-optical microscopic switches and amplifiers. 105 polaritons occupy the same quantum state during the amplification, realizing a dynamical condensate of strongly interacting bosons which can be studied at high temperature. PMID:11742394

  7. High-temperature ultrafast polariton parametric amplification in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Saba, M.; Ciuti, C.; Bloch, J.; Thierry-Mieg, V.; André, R.; Dang, Le Si; Kundermann, S.; Mura, A.; Bongiovanni, G.; Staehli, J. L.; Deveaud, B.

    2001-12-01

    Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons. Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures. Here we demonstrate polariton parametric amplification up to 120K in GaAlAs-based microcavities and up to 220K in CdTe-based microcavities. We show that the cut-off temperature for the amplification is ultimately determined by the binding energy of the exciton. A 5-µm-thick planar microcavity can amplify a weak light pulse more than 5,000 times. The effective gain coefficient of an equivalent homogeneous medium would be 107cm-1. The subpicosecond duration and high efficiency of the amplification could be exploited for high-repetition all-optical microscopic switches and amplifiers. 105 polaritons occupy the same quantum state during the amplification, realizing a dynamical condensate of strongly interacting bosons which can be studied at high temperature.

  8. Relative intensity noise in high speed microcavity laser

    NASA Astrophysics Data System (ADS)

    Tan, F.; Wu, M. K.; Liu, M.; Feng, M.; Holonyak, N.

    2013-09-01

    We have fabricated a high speed single mode microcavity laser of the form of oxide-confined vertical cavity surface emitting laser (VCSEL) and achieved an ultralow threshold current (ITH = 0.13 mA at 20 °C) with lasing wavelength at 837 nm. The optical spectrum of the microcavity VCSEL exhibits a mode spacing of 3.1 nm, which is corresponding to an optical modal cavity dimension of 2.5 μm. The device exhibits an enhanced modulation bandwidth of 22.6 GHz and a thermal noise limited laser intensity noise (electrical power spectral density of laser intensity noise below the thermal noise floor -174 dBm/Hz) as a consequence of low power laser operation and reduced mode competition in the microcavity.

  9. Carbon nanotube biconvex microcavities

    SciTech Connect

    Butt, Haider Ahmed, Rajib; Yetisen, Ali K.; Yun, Seok Hyun; Dai, Qing

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  10. Multiwall carbon nanotube microcavity arrays

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Yetisen, Ali K.; Dai, Qing; Yun, Seok Hyun; Butt, Haider

    2016-03-01

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm2) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170-180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  11. Numerical investigation of high-contrast ultrafast all-optical switching in low-refractive-index polymeric photonic crystal nanobeam microcavities

    NASA Astrophysics Data System (ADS)

    Meng, Zi-Ming; Zhong, Xiao-Lan; Wang, Chen; Li, Zhi-Yuan

    2012-06-01

    With the development of micro- or nano-fabrication technologies, great interest has been aroused in exploiting photonic crystal nanobeam structures. In this article the design of high-quality-factor (Q) polymeric photonic crystal nanobeam microcavities suitable for realizing ultrafast all-optical switching is presented based on the three-dimensional finite-difference time-domain method. Adopting the pump-probe technique, the ultrafast dynamic response of the all-optical switching in a nanobeam microcavity with a quality factor of 1000 and modal volume of 1.22 (λ/n)3 is numerically studied and a switching time as fast as 3.6 picoseconds is obtained. Our results indicate the great promise of applying photonic crystal nanobeam microcavities to construct integrated ultrafast tunable photonic devices or circuits incorporating polymer materials with large Kerr nonlinearity and ultrafast response speed.

  12. Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon

    PubMed Central

    Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T.

    2012-01-01

    Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ~9,300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 picograms/mm2 Highest sensitivity, irrespective of the dissociation constant Kd, is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1μg/ml. PMID:22748964

  13. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  14. Magneto-exciton-polariton condensation in a sub-wavelength high contrast grating based vertical microcavity

    SciTech Connect

    Fischer, J.; Brodbeck, S.; Worschech, L.; Kamp, M.; Schneider, C.; Höfling, S.; Zhang, B.; Wang, Z.; Deng, H.

    2014-03-03

    We comparably investigate the diamagnetic shift of an uncoupled quantum well exciton with a microcavity exciton-polariton condensate on the same device. The sample is composed of multiple GaAs quantum wells in an AlAs microcavity, surrounded by a Bragg reflector and a sub-wavelength high contrast grating reflector. Our study introduces an independent and easily applicable technique, namely, the measurement of the condensate diamagnetic shift, which directly probes matter contributions in polariton condensates and hence discriminates it from a conventional photon laser.

  15. Abnormal high-Q modes of coupled stadium-shaped microcavities.

    PubMed

    Ryu, Jung-Wan; Lee, Soo-Young; Kim, Inbo; Choi, Muhan; Hentschel, Martina; Kim, Sang Wook

    2014-07-15

    It is well known that the strongly deformed microcavity with fully chaotic ray dynamics cannot support high-Q modes due to its fast chaotic diffusion to the critical line of refractive emission. Here, we investigate how the Q factor is modified when two chaotic cavities are coupled, and show that some modes, whose Q factor is about 10 times higher than that of the corresponding single cavity, can exist. These abnormal high-Q modes are the result of an optimal combination of coupling and cavity geometry. As an example, in the coupled stadium-shaped microcavities, the mode pattern extends over both cavities such that it follows a whispering-gallery-type mode at both ends, whereas a big coupling spot forms at the closest contact of the two microcavities. The pattern of such a "rounded bow tie" mode allows the mode to have a high-Q factor. This mode pattern minimizes the leakage of light at both ends of the microcavities as the pattern at both ends is similar to the whispering gallery mode. PMID:25121685

  16. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-01

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10-7 RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  17. Laser-Machined Microcavities for Simultaneous Measurement of High-Temperature and High-Pressure

    PubMed Central

    Ran, Zengling; Liu, Shan; Liu, Qin; Huang, Ya; Bao, Haihong; Wang, Yanjun; Luo, Shucheng; Yang, Huiqin; Rao, Yunjiang

    2014-01-01

    Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ∼0.0779 nm/°C and ∼1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ∼32.3 nm/°C and ∼24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions. PMID:25106018

  18. The role of group index engineering in series-connected photonic crystal microcavities for high density sensor microarrays

    SciTech Connect

    Zou, Yi Zhu, Liang; Chen, Ray T.; Chakravarty, Swapnajit

    2014-04-07

    We experimentally demonstrate an efficient and robust method for series connection of photonic crystal microcavities that are coupled to photonic crystal waveguides in the slow light transmission regime. We demonstrate that group index taper engineering provides excellent optical impedance matching between the input and output strip waveguides and the photonic crystal waveguide, a nearly flat transmission over the entire guided mode spectrum and clear multi-resonance peaks corresponding to individual microcavities that are connected in series. Series connected photonic crystal microcavities are further multiplexed in parallel using cascaded multimode interference power splitters to generate a high density silicon nanophotonic microarray comprising 64 photonic crystal microcavity sensors, all of which are interrogated simultaneously at the same instant of time.

  19. Diamond based photonic crystal microcavities.

    PubMed

    Tomljenovic-Hanic, S; Steel, M J; de Sterke, C Martijn; Salzman, J

    2006-04-17

    Diamond based technologies offer a material platform for the implementation of qubits for quantum computing. The photonic crystal architecture provides the route for a scalable and controllable implementation of high quality factor (Q) nanocavities, operating in the strong coupling regime for cavity quantum electrodynamics. Here we compute the photonic band structures and quality factors of microcavities in photonic crystal slabs in diamond, and compare the results with those of the more commonly-used silicon platform. We find that, in spite of the lower index contrast, diamond based photonic crystal microcavities can exhibit quality factors of Q=3.0x10(4), sufficient for proof of principle demonstrations in the quantum regime. PMID:19516502

  20. Recent Progress in the Growth of Highly Reflective Nitride-Based Distributed Bragg Reflectors and Their Use in Microcavities

    NASA Astrophysics Data System (ADS)

    Butté, R.; Feltin, E.; Dorsaz, J.; Christmann, G.; Carlin, J.-F.; Grandjean, N.; Ilegems, M.

    2005-10-01

    The growth of highly-reflective nitride-based distributed Bragg reflectors (DBRs) and their use in vertical cavity structures is reviewed. We discuss the various nitride material systems employed to design Bragg mirrors and microcavities, namely the Alx(Ga)1-xN/(Al)yGa1-yN and the lattice-matched Al1-xInxN/GaN (xIn˜ 18%)-based systems. An emphasis on particular issues such as strain management, internal absorption, alloy morphology and contribution of leaky modes is carried out. Specific properties of the poorly known AlInN alloy such as the bandgap variation with In content close to lattice-matched conditions to GaN are reported. The superior optical quality of the lattice-matched AlInN/GaN system for the realization of nitride-based DBRs is demonstrated. The properties of nitride-based vertical cavity devices are also described. Forthcoming challenges such as the realization of electrically pumped vertical cavity surface emitting lasers and strongly coupled quantum microcavities are discussed as well, and in particular critical issues such as vertical current injection.

  1. ZnO-Based Microcavities Sculpted by Focus Ion Beam Milling.

    PubMed

    Chang, Tsu-Chi; Hong, Kuo-Bin; Lai, Ying-Yu; Chou, Yu-Hsun; Wang, Shing-Chung; Lu, Tien-Chang

    2016-12-01

    We reported an easy fabrication method to realize ZnO-based microcavities with various cavity shapes by focused ion beam (FIB) milling. The optical characteristics of different shaped microcavities have been systematically carried out and analyzed. Through comprehensive studies of cathodoluminescence and photoluminescence spectra, the whispering gallery mode (WGM) was observed in different shaped microcavities. Up further increasing excitation, the lasing action was dominated by these WGMs and matched very well to the simulated results. Our experiment shows that ZnO microcavities with different shapes can be made with high quality by FIB milling for specific applications of microlight sources and optical devices. PMID:27364999

  2. ZnO-Based Microcavities Sculpted by Focus Ion Beam Milling

    NASA Astrophysics Data System (ADS)

    Chang, Tsu-Chi; Hong, Kuo-Bin; Lai, Ying-Yu; Chou, Yu-Hsun; Wang, Shing-Chung; Lu, Tien-Chang

    2016-06-01

    We reported an easy fabrication method to realize ZnO-based microcavities with various cavity shapes by focused ion beam (FIB) milling. The optical characteristics of different shaped microcavities have been systematically carried out and analyzed. Through comprehensive studies of cathodoluminescence and photoluminescence spectra, the whispering gallery mode (WGM) was observed in different shaped microcavities. Up further increasing excitation, the lasing action was dominated by these WGMs and matched very well to the simulated results. Our experiment shows that ZnO microcavities with different shapes can be made with high quality by FIB milling for specific applications of microlight sources and optical devices.

  3. Ultra-high Q one-dimensional hybrid PhC-SPP waveguide microcavity with large structure tolerance

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Zhang, Lingxuan; Lu, Xiaoyuan; Wang, Weiqiang; Wang, Leiran; Wang, Guoxi; Zhang, Wenfu; Zhao, Wei

    2016-07-01

    A photonic crystal - surface plasmon-polaritons hybrid transverse magnetic mode waveguide based on a one-dimensional optical microcavity is designed to work in the communication band. A Gaussian field distribution in a stepping heterojunction taper is designed by band engineering, and a silica layer compresses the mode field to the subwavelength scale. The designed microcavity possesses a resonant mode with a quality factor of 1609 and a modal volume of 0.01 cubic wavelength. The constant period and the large structure tolerance make it realizable by current processing techniques.

  4. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    SciTech Connect

    Chakravarty, Swapnajit Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-12

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10{sup −7} RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  5. Titanium-enhanced Raman microcavity laser.

    PubMed

    Deka, Nishita; Maker, Ashley J; Armani, Andrea M

    2014-03-15

    Whispering gallery mode microcavities are ideally suited to form microlaser devices because the high circulating intensity within the cavity results in ultralow lasing thresholds. However, to achieve low-threshold Raman lasing in silica devices, it is necessary to have quality factors above 100 million. One approach to circumvent this restriction is to intercalate a sensitizer into the silica, which increases the Raman gain. In the present work, we demonstrate a Raman laser based on a titanium sensitized silica solgel coated toroidal microcavity. By tuning the concentration of the Ti, the Raman efficiency improves over 3× while maintaining sub-mW thresholds. PMID:24690786

  6. Narrowband thermal radiation from closed-end microcavities

    SciTech Connect

    Kohiyama, Asaka; Shimizu, Makoto; Iguchi, Fumitada; Yugami, Hiroo

    2015-10-07

    High spectral selectivity of thermal radiation is important for achieving high-efficiency energy systems. In this study, intense, narrowband, and low directional absorption/radiation were observed in closed-end microcavity which is a conventional open-end microcavity covered by a semi-transparent thin metal film. The quality factor (Q factor) of optical absorption band strongly depended on the film electrical conductivity. Asymmetric and narrow absorption band with a Q factor of 25 at 1.28 μm was obtained for a 6-nm-thick Au film. Numerical simulations suggest that the formation of a fixed-end mode at the cavity aperture contributes to the narrowband optical absorption. The closed-end microcavity filled with SiO{sub 2} exhibits intense and isotropic thermal radiation over a wide solid angle according to numerical simulation. The narrow and asymmetric absorption spectrum was experimentally confirmed in a model of closed-end microcavity.

  7. Photonic crystal microcavity engineering and high-density bio-patterning for chip-integrated microarray applications

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Chen, Ray T.

    2012-01-01

    While Q ~ 1million has been demonstrated in freely suspended photonic crystal (PC) membranes, the reduced refractive index contrast when PC microcavities are immersed in phosphate buffered saline (PBS), a typical ambient for biomolecules, reduces Q by more than 2 orders of magnitude. We experimentally demonstrate photonic crystal microcavity based resonant sensors coupled to photonic crystal waveguides in silicon on insulator for chemical and bio-sensing. Linear L-type microcavities are considered. In contrast to cavities with small modes volumes but low quality factors for bio-sensing, we show that increasing the length of the microcavity enhances the quality factor of the resonance by an order of magnitude and also increases the resonance wavelength shift while still retaining compact device characteristics. Q~26,760 and sensitivity down to 7.5ng/ml and ~9pg/mm2 in bio-sensing was experimentally demonstrated in SOI devices for goat anti-rabbit IgG antibodies with Kd~10-6M. The increase in cavity length follows from fundamental engineering limitations in ink-jet printing or microfluidic channels when unique receptor biomolecules are coated on separate adjacent sensors in a microarray.

  8. Optical Microcavity: Sensing down to Single Molecules and Atoms

    PubMed Central

    Yoshie, Tomoyuki; Tang, Lingling; Su, Shu-Yu

    2011-01-01

    This review article discusses fundamentals of dielectric, low-loss, optical micro-resonator sensing, including figures of merit and a variety of microcavity designs, and future perspectives in microcavity-based optical sensing. Resonance frequency and quality (Q) factor are altered as a means of detecting a small system perturbation, resulting in realization of optical sensing of a small amount of sample materials, down to even single molecules. Sensitivity, Q factor, minimum detectable index change, noises (in sensor system components and microcavity system including environments), microcavity size, and mode volume are essential parameters to be considered for optical sensing applications. Whispering gallery mode, photonic crystal, and slot-type microcavities typically provide compact, high-quality optical resonance modes for optical sensing applications. Surface Bloch modes induced on photonic crystals are shown to be a promising candidate thanks to large field overlap with a sample and ultra-high-Q resonances. Quantum optics effects based on microcavity quantum electrodynamics (QED) would provide novel single-photo-level detection of even single atoms and molecules via detection of doublet vacuum Rabi splitting peaks in strong coupling. PMID:22319393

  9. Strong exciton-photon coupling with colloidal quantum dots in a high-Q bilayer microcavity

    SciTech Connect

    Giebink, Noel C; Wiederrecht, Gary P.; Wasielewski, Michael R

    2011-01-01

    We demonstrate evanescently coupled bilayer microcavities with Q -factors exceeding 250 fabricated by a simple spin-coating process. The cavity architecture consists of a slab waveguide lying upon a low refractive index spacer layer supported by a glass substrate. For a lossless guide layer, the cavity Q depends only on the thickness of the low index spacer and in principle can reach arbitrarily high values. We demonstrate the versatility of this approach by constructing cavities with a guide layer incorporating CdSe/ZnS core/shell quantum dots, where we observe strong coupling and hybridization between the 1S(e)-1S{sub 3/2} (h) and 1S(e)-2S{sub 3/2} (h) exciton states mediated by the cavity photon. This technique greatly simplifies the fabrication of high-Q planar microcavities for organic and inorganic quantum dot thin films and opens up new opportunities for the study of nonlinear optical phenomena in these materials.

  10. Detection of Single Nanoparticles Using the Dissipative Interaction in a High-Q Microcavity

    NASA Astrophysics Data System (ADS)

    Shen, Bo-Qiang; Yu, Xiao-Chong; Zhi, Yanyan; Wang, Li; Kim, Donghyun; Gong, Qihuang; Xiao, Yun-Feng

    2016-02-01

    Ultrasensitive optical detection of nanometer-scaled particles is highly desirable for applications in early-stage diagnosis of human diseases, environmental monitoring, and homeland security, but remains extremely difficult due to ultralow polarizabilities of small-sized, low-index particles. Optical whispering-gallery-mode microcavities, which can enhance significantly the light-matter interaction, have emerged as promising platforms for label-free detection of nanoscale objects. Different from the conventional whispering-gallery-mode sensing relying on the reactive (i.e., dispersive) interaction, here we propose and demonstrate to detect single lossy nanoparticles using the dissipative interaction in a high-Q toroidal microcavity. In the experiment, detection of single gold nanorods in an aqueous environment is realized by monitoring simultaneously the linewidth change and shift of the cavity mode. The experimental result falls within the theoretical prediction. Remarkably, the reactive and dissipative sensing methods are evaluated by setting the probe wavelength on and off the surface plasmon resonance to tune the absorption of nanorods, which demonstrates clearly the great potential of the dissipative sensing method to detect lossy nanoparticles. Future applications could also combine the dissipative and reactive sensing methods, which may provide better characterizations of nanoparticles.

  11. Three-Dimensional Microcavity Array Electrodes for High-Capacitance All-Solid-State Flexible Microsupercapacitors.

    PubMed

    Maeng, Jimin; Kim, Young-Joon; Meng, Chuizhou; Irazoqui, Pedro P

    2016-06-01

    We report novel three-dimensional (3D) microcavity array electrodes for high-capacitance all-solid-state microsupercapactiors. The microcavity arrays are formed in a polymer substrate via a plasma-assisted reactive ion etching (RIE) process and provide extra sidewall surface areas on which the active materials are grown in the form of nanofibers. This 3D structure leads to an increase in the areal capacitance by a factor of 2.56 for a 15-μm-deep cavity etching, agreeing well with the prediction. The fabricated microsupercapactiors exhibit a maximum areal capacitance of 65.1 mF cm(-2) (a volumetric capacitance of 93.0 F cm(-3)) and an energy density of 0.011 mWh cm(-2) (a volumetric energy density of 16.4 mWh cm(-3)) which substantially surpass previously reported values for all-solid-state flexible microsupercapacitors. The devices show good electrochemical stability under extended voltammetry cycles and bending cycles. It is demonstrated that they can sustain a radio frequency (rf) microsystem in a temporary absence of a power supply. These results suggest the potential utility of our 3D microsupercapactiors as miniaturized power sources in wearable and implantable medical devices. PMID:27176134

  12. High-Q planar organic-inorganic Perovskite-based microcavity.

    PubMed

    Han, Zheng; Nguyen, Hai-Son; Boitier, Fabien; Wei, Yi; Abdel-Baki, Katia; Lauret, Jean-Sébastien; Bloch, Jacqueline; Bouchoule, Sophie; Deleporte, Emmanuelle

    2012-12-15

    We report on the fabrication of a perovskite-based ((C6H5C2H4 - NH3)2 PbI4) planar microcavity with a technique of a top dielectric mirror's migration in liquid, avoiding the degradation of the perovskite material. This approach allows for increasing the cavity Q-factor, without degrading the fragile molecular material. Strong coupling of the perovskite exciton to both the cavity mode and the first Bragg mode is evidenced from angle-resolved reflectivity and microphotoluminescence measurements at room temperature; an efficient relaxation toward the minimum of the main polariton branch is observed. The measured quality factor is significantly increased compared to previous reports where a top metallic mirror was used, showing the decisive advantage of the present fabrication technique toward the achievement of stimulated effects and polariton lasing with perovskite materials. PMID:23258005

  13. Micro-cavity lasers with large device size for directional emission

    NASA Astrophysics Data System (ADS)

    Yan, Chang-ling; Li, Peng; Shi, Jian-wei; Feng, Yuan; Hao, Yong-qin; Zhu, Dongda

    2014-10-01

    Optical micro-cavity structures, which can confine light in a small mode volume with high quality factors, have become an important platform not only for optoelectronic applications with densely integrated optical components, but also for fundamental studies such as cavity quantum electrodynamics and nonlinear optical processes. Micro-cavity lasers with directional emission feature are becoming a promising resonator for the compact laser application. In this paper, we presented the limason-shaped cavity laser with large device size, and fabricated this type of micro-cavity laser with quantum cascade laser material. The micro-cavity laser with large device size was fabricated by using InP based InGaAs/InAlAs quantum cascade lasers material at about 10um emitting wavelength, and the micro-cavity lasers with the large device size were manufactured and characterized with light output power, threshold current, and the far-field pattern.

  14. Fermi Edge Polaritons in a Microcavity Containing a High Density Two-Dimensional Electron Gas

    NASA Astrophysics Data System (ADS)

    Gabbay, A.; Preezant, Yulia; Cohen, E.; Ashkinadze, B. M.; Pfeiffer, L. N.

    2007-10-01

    Sharp, near band gap lines are observed in the reflection and photoluminescence spectra of GaAs/AlGaAs structures consisting of a modulation doped quantum well (MDQW) that contains a high density two-dimensional electron gas (2DEG) and is embedded in a microcavity (MC). The energy dependence of these lines on the MC-confined photon energy shows level anticrossings and Rabi splittings very similar to those observed in systems of undoped QW’s embedded in a MC. The spectra are analyzed by calculating the optical susceptibility of the MDQW in the near band gap spectral range and using it within the transfer matrix method. The calculated reflection spectra indicate that the sharp spectral lines are due to k∥=0 cavity polaritons that are composed of e-h pair excitations just above the 2DEG Fermi edge and are strongly coupled to the MC-confined photons.

  15. Optofluidic laser array based on stable high-Q Fabry-Pérot microcavities.

    PubMed

    Wang, Wenjie; Zhou, Chunhua; Zhang, Tingting; Chen, Jingdong; Liu, Shaoding; Fan, Xudong

    2015-10-01

    We report the development of an optofluidic laser array fabricated on a chip using stable plano-concave Fabry-Pérot (FP) microcavities, which are far less susceptible to optical misalignment during device assembly than the commonly used plano-plano FP microcavities. The concave mirrors in our FP microcavities were created by first generating an array of microwells of a few micrometers in depth and a few tens of micrometers in diameter on a fused silica chip using a CO2 laser, followed by coating of distributed Bragg reflection (DBR) layers. The plano-concave FP microcavity had a Q-factor of 5.6 × 10(5) and finesse of 4 × 10(3), over 100 times higher than those for the FP microcavities in existing optofluidic lasers. 1 mM R6G dye in ethanol was used to test the plano-concave FP microcavities, showing an ultralow lasing threshold of only 90 nJ mm(-2), over 10 times lower than that in the corresponding unstable plano-plano FP microcavities formed by the same DBR coatings on the same chip. Simultaneous laser emission from the optofluidic laser array on the chip and single-mode lasing operation were also demonstrated. Our work will lead to the development of optofluidic laser-based biochemical sensors and novel on-chip photonic devices with extremely low lasing thresholds (nJ mm(-2)) and mode volumes (fL). PMID:26304622

  16. Label-free detection with high-Q microcavities: a review of biosensing mechanisms for integrated devices

    PubMed Central

    Yang, Lan

    2015-01-01

    Optical microcavities that confine light in high-Q resonance promise all of the capabilities required for a successful next-generation microsystem biodetection technology. Label-free detection down to single molecules as well as operation in aqueous environments can be integrated cost-effectively on microchips, together with other photonic components, as well as electronic ones. We provide a comprehensive review of the sensing mechanisms utilized in this emerging field, their physics, engineering and material science aspects, and their application to nanoparticle analysis and biomolecular detection. We survey the most recent developments such as the use of mode splitting for self-referenced measurements, plasmonic nanoantennas for signal enhancements, the use of optical force for nanoparticle manipulation as well as the design of active devices for ultra-sensitive detection. Furthermore, we provide an outlook on the exciting capabilities of functionalized high-Q microcavities in the life sciences. PMID:26918228

  17. High-Polarization-Discriminating Infrared Detection Using a Single Quantum Well Sandwiched in Plasmonic Micro-Cavity

    PubMed Central

    Li, Qian; Li, ZhiFeng; Li, Ning; Chen, XiaoShuang; Chen, PingPing; Shen, XueChu; Lu, Wei

    2014-01-01

    Polarimetric imaging has proved its value in medical diagnostics, bionics, remote sensing, astronomy, and in many other wide fields. Pixel-level solid monolithically integrated polarimetric imaging photo-detectors are the trend for infrared polarimetric imaging devices. For better polarimetric imaging performance the high polarization discriminating detectors are very much critical. Here we demonstrate the high infrared light polarization resolving capabilities of a quantum well (QW) detector in hybrid structure of single QW and plasmonic micro-cavity that uses QW as an active structure in the near field regime of plasmonic effect enhanced cavity, in which the photoelectric conversion in such a plasmonic micro-cavity has been realized. The detector's extinction ratio reaches 65 at the wavelength of 14.7 μm, about 6 times enhanced in such a type of pixel-level polarization long wave infrared photodetectors. The enhancement mechanism is attributed to artificial plasmonic modulation on optical propagation and distribution in the plasmonic micro-cavities. PMID:25208580

  18. High-Polarization-Discriminating Infrared Detection Using a Single Quantum Well Sandwiched in Plasmonic Micro-Cavity

    NASA Astrophysics Data System (ADS)

    Li, Qian; Li, Zhifeng; Li, Ning; Chen, Xiaoshuang; Chen, Pingping; Shen, Xuechu; Lu, Wei

    2014-09-01

    Polarimetric imaging has proved its value in medical diagnostics, bionics, remote sensing, astronomy, and in many other wide fields. Pixel-level solid monolithically integrated polarimetric imaging photo-detectors are the trend for infrared polarimetric imaging devices. For better polarimetric imaging performance the high polarization discriminating detectors are very much critical. Here we demonstrate the high infrared light polarization resolving capabilities of a quantum well (QW) detector in hybrid structure of single QW and plasmonic micro-cavity that uses QW as an active structure in the near field regime of plasmonic effect enhanced cavity, in which the photoelectric conversion in such a plasmonic micro-cavity has been realized. The detector's extinction ratio reaches 65 at the wavelength of 14.7 μm, about 6 times enhanced in such a type of pixel-level polarization long wave infrared photodetectors. The enhancement mechanism is attributed to artificial plasmonic modulation on optical propagation and distribution in the plasmonic micro-cavities.

  19. High-polarization-discriminating infrared detection using a single quantum well sandwiched in plasmonic micro-cavity.

    PubMed

    Li, Qian; Li, ZhiFeng; Li, Ning; Chen, XiaoShuang; Chen, PingPing; Shen, XueChu; Lu, Wei

    2014-01-01

    Polarimetric imaging has proved its value in medical diagnostics, bionics, remote sensing, astronomy, and in many other wide fields. Pixel-level solid monolithically integrated polarimetric imaging photo-detectors are the trend for infrared polarimetric imaging devices. For better polarimetric imaging performance the high polarization discriminating detectors are very much critical. Here we demonstrate the high infrared light polarization resolving capabilities of a quantum well (QW) detector in hybrid structure of single QW and plasmonic micro-cavity that uses QW as an active structure in the near field regime of plasmonic effect enhanced cavity, in which the photoelectric conversion in such a plasmonic micro-cavity has been realized. The detector's extinction ratio reaches 65 at the wavelength of 14.7 μm, about 6 times enhanced in such a type of pixel-level polarization long wave infrared photodetectors. The enhancement mechanism is attributed to artificial plasmonic modulation on optical propagation and distribution in the plasmonic micro-cavities. PMID:25208580

  20. Ultrasmooth silver thin film electrodes with high polar liquid wettability for OLED microcavity application.

    PubMed

    Cioarec, Cristina; Melpignano, Patrizia; Gherardi, Nicolas; Clergereaux, Richard; Villeneuve, Christina

    2011-04-01

    For a lab-on-chip application, we fabricate a blue bottom emitting strong microcavity organic light emitting diode (OLED), using very smooth and optically thin (25 nm) silver film as anode on a glass substrate. To improve the hole injection in the OLED device, PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)) has been used, so the silver anode must present not only a very smooth surface but also a strong adherence on the glass and a high wettability to allow a good PEDOT-PSS spin coating deposition. To obtain these physical properties, different 5 nm thick nucleation layers (germanium, chromium, and hydrogenated amorphous carbon) have been used to grow the silver thin films by e-beam deposition. The Ge/Ag bilayer presents all the desired properties: this bilayer, investigated by ellipsometry, optical profilometry, contact angle measurements, and XPS analysis, highlights an ultrasmooth surface correlated with the film growth mode and a high wettability related to its surface chemical composition. PMID:21391637

  1. Mode characteristics and directional emission for square microcavity lasers

    NASA Astrophysics Data System (ADS)

    Yang, Yue-De; Huang, Yong-Zhen

    2016-06-01

    Square microcavities with high quality factor whispering-gallery-like modes have a series of novel optical properties and can be employed as compact-size laser resonators. In this paper, the mode characteristics of square optical microcavities and the lasing properties of directional-emission square semiconductor microlasers are reviewed for the realization of potential light sources in the photonic integrated circuits and optical interconnects. A quasi-analytical model is introduced to describe the confined modes in square microcavities, and high quality factor whispering-gallery-like modes are predicted by the mode-coupling theory and confirmed by the numerical simulation. An output waveguide directly coupled to the position with weak mode field is used to achieve directional emission and control the lasing mode. Electrically-pumped InP-based directional-emission square microlasers are realized at room temperature, and the lasing spectra agree well with the mode analysis. Different kinds of square microcavity lasers, including dual-mode laser with a tunable interval, single-mode laser with a wide tunable wavelength range, and high-speed direct-modulated laser are also demonstrated experimentally.

  2. Photonic crystal microcavity lasers and laser arrays

    NASA Astrophysics Data System (ADS)

    Cao, Jiang-Rong

    As a state-of-the-art technology, photonic crystal microcavity lasers have great potentials to resolve many semiconductor laser performance challenges, owing to their compact size, high spontaneous emission factor, and inherent advantages in dimension scalability. This thesis describes efficient numerical analyzing methods for multimode photonic crystal microcavities, including a parallel computing three-dimensional finite-difference time-domain method combined with Pade interpolation, point group projection, and vectorial Green's function method. With the help of these analyzing tools, various experimental photonic crystal microcavity devices fabricated in InGaAsP/InP based materials were studies. Room temperature optical pumped InGaAsP suspended membrane photonic crystal microcavity lasers were demonstrated. Their lithographical fine-tuning, above room temperature operations, mode identifications and polarizations were demonstrated. Room temperature continuous wave (CW) optically pumped photonic crystal microcavity lasers at diameter less than 3.2 mum were demonstrated with crystalline alpha-Al 2O3 (sapphire) as a cladding layer to the InGaAsP membrane. The far-field radiation profiles from these microcavity lasers were measured and compared with our numerical modeling predictions. Two electrical injection scenes for photonic crystal microcavity lasers were introduced, together with some preliminary results including the demonstrations of optically pumped lasing of highly doped cavities and cavities with an electrical conduction post underneath. Electrically excited photonic crystal microcavity light emitting diodes (LEDs) were also experimentally demonstrated.

  3. Semiconductor microcavity lasers

    SciTech Connect

    Gourley, P.L.; Wendt, J.R.; Vawter, G.A.; Warren, M.E.; Brennan, T.M.; Hammons, B.E.

    1994-02-01

    New kinds of semiconductor microcavity lasers are being created by modern semiconductor technologies like molecular beam epitaxy and electron beam lithography. These new microcavities exploit 3-dimensional architectures possible with epitaxial layering and surface patterning. The physical properties of these microcavities are intimately related to the geometry imposed on the semiconductor materials. Among these microcavities are surface-emitting structures which have many useful properties for commercial purposes. This paper reviews the basic physics of these microstructured lasers.

  4. High-temperature continuous-wave laser realized in hollow microcavities

    PubMed Central

    Shi, Zhifeng; Zhang, Yuantao; Cui, Xijun; Zhuang, Shiwei; Wu, Bin; Dong, Xin; Zhang, Baolin; Du, Guotong

    2014-01-01

    Recently, an urgent requirement of ultraviolet (UV) semiconductor laser with lower cost and higher performance has motivated our intensive research in zinc oxide (ZnO) material owing to its wide direct band gap and large exciton binding energy. Here, we demonstrate for the first time continuous-wave laser in electrically-pumped hollow polygonal microcavities based on epitaxial ZnO/MgO-core/shell nanowall networks structures, and whispering gallery type resonant modes are responsible for the lasing action. The laser diodes exhibit an ultralow threshold current density (0.27 A/cm2), two or three orders of magnitude smaller than other reported UV-light semiconductor laser diodes to our knowledge. More importantly, the continuous-current-driven diode can achieve lasing up to ~430 K, showing a good temperature tolerance. This study indicates that nano-size injection lasers can be made from epitaxial semiconductor microcavities, which is a considerable advance towards the realization of practical UV coherent light sources, facilitating the existing applications and suggesting new potentials. PMID:25417966

  5. Silicon on-chip side-coupled high-Q micro-cavities for the multiplexing of high sensitivity photonic crystal integrated sensors array

    NASA Astrophysics Data System (ADS)

    Yang, Daquan; Wang, Chunhong; Yuan, Wei; Wang, Bo; Yang, Yujie; Ji, Yuefeng

    2016-09-01

    A novel two-dimensional (2D) silicon (Si) photonic crystal (PC) α-H0-slot micro-cavity with high Q-factor and high sensitivity (S) is presented. Based on the proposed α-H0-Slot micro-cavities, an optimal design of photonic crystal integrated sensors array (PC-ISA) on monolithic silicon on insulator (SOI) is displayed. By using finite-difference time-domain (FDTD) method, the simulation results demonstrate that both large S of 200 nm/RIU (RIU=refractive index unit) and high Q-factor >104 at telecom wavelength range can be achieved simultaneously. And the sensor figure of merit (FOM)>7000 is featured, an order of magnitude improvement over previous 2D PC sensors array. In addition, for the proposed 2D PC-ISA device, each sensor unit is shown to independently shift its resonance wavelength in response to the changes in refractive index (RI) and does not perturb the others. Thus, it is potentially an ideal platform for realizing ultra-compact lab-on-a-chip applications with dense arrays of functionalized spots for multiplexed sensing, and also can be used as an opto-fluidic architecture for performing highly parallel detection of biochemical interactions in aqueous environments.

  6. Fabry-Perot microcavity for diamond-based photonics

    NASA Astrophysics Data System (ADS)

    Janitz, Erika; Ruf, Maximilian; Dimock, Mark; Bourassa, Alexandre; Sankey, Jack; Childress, Lilian

    2015-10-01

    Open Fabry-Perot microcavities represent a promising route for achieving a quantum electrodynamics (cavity-QED) platform with diamond-based emitters. In particular, they offer the opportunity to introduce high-purity, minimally fabricated material into a tunable, high quality factor optical resonator. Here, we demonstrate a fiber-based microcavity incorporating a thick (>10 μ m ) diamond membrane with a finesse of 17 000, corresponding to a quality factor Q ˜106 . Such minimally fabricated thick samples can contain optically stable emitters similar to those found in bulk diamond. We observe modified microcavity spectra in the presence of the membrane, and we develop analytic and numerical models to describe the effect of the membrane on cavity modes, including loss and coupling to higher-order transverse modes. We estimate that a Purcell enhancement of approximately 20 should be possible for emitters within the diamond in this device, and we provide evidence that better diamond surface treatments and mirror coatings could increase this value to 200 in a realistic system.

  7. Spherical silicon photonic microcavities: From amorphous to polycrystalline

    NASA Astrophysics Data System (ADS)

    Fenollosa, R.; Garín, M.; Meseguer, F.

    2016-06-01

    Shaping silicon as a spherical object is not an obvious task, especially when the object size is in the micrometer range. This has the important consequence of transforming bare silicon material in a microcavity, so it is able to confine light efficiently. Here, we have explored the inside volume of such microcavities, both in their amorphous and in their polycrystalline versions. The synthesis method, which is based on chemical vapor deposition, causes amorphous microspheres to have a high content of hydrogen that produces an onionlike distributed porous core when the microspheres are crystallized by a fast annealing regime. This substantially influences the resonant modes. However, a slow crystallization regime does not yield pores, and produces higher-quality-factor resonances that could be fitted to the Mie theory. This allows the establishment of a procedure for obtaining size calibration standards with relative errors of the order of 0.1%.

  8. Ultrasensitive detection of mode splitting in active optical microcavities

    SciTech Connect

    He, Lina; Oezdemir, Sahin Kaya; Zhu Jiangang; Yang Lan

    2010-11-15

    Scattering-induced mode splitting in active microcavities is demonstrated. Below the lasing threshold, quality factor enhancement by optical gain allows resolving, in the wavelength-scanning transmission spectrum, of resonance dips of the split modes which otherwise would not be detected in a passive resonator. In the lasing regime, mode splitting manifests itself as two lasing modes with extremely narrow linewidths. Mixing these lasing modes in a detector leads to a heterodyne beat signal whose frequency corresponds to the mode-splitting amount. Lasing regime not only allows ultra-high sensitivity for mode-splitting measurements but also provides an easily accessible scheme by eliminating the need for wavelength scanning around resonant modes. Mode splitting in active microcavities has an immediate impact in enhancing the sensitivity of subwavelength scatterer detection and in studying light-matter interactions in a strong-coupling regime.

  9. A tunable microcavity

    NASA Astrophysics Data System (ADS)

    Barbour, Russell J.; Dalgarno, Paul A.; Curran, Arran; Nowak, Kris M.; Baker, Howard J.; Hall, Denis R.; Stoltz, Nick G.; Petroff, Pierre M.; Warburton, Richard J.

    2011-09-01

    We present a generic microcavity platform for cavity experiments on optically active nanostructures, such as quantum dots, nanocrystals, color centers, and carbon nanotubes. The cavity is of the Fabry-Pérot type with a planar back mirror and a miniature concave top mirror with radius of curvature ˜ 100 μm. Optical access is achieved by free beam coupling, allowing good mode-matching to the cavity mode. The cavity has a high Q-factor, reasonably small mode volume, open access, spatial and spectral tunability, and operates at cryogenic temperatures. Spectral and spatial tuning of the Purcell effect (weak coupling regime) on a single InGaAs quantum dot is demonstrated.

  10. Aqueous-filled polymer microcavity arrays: versatile & stable lipid bilayer platforms offering high lateral mobility to incorporated membrane proteins.

    PubMed

    Basit, Hajra; Gaul, Vinnie; Maher, Sean; Forster, Robert J; Keyes, Tia E

    2015-05-01

    A key prerequisite in an ideal supported lipid bilayer based cell membrane model is that the mobility of both the lipid matrix and its components are unhindered by the underlying support. This is not trivial and with the exception of liposomes, many of even the most advanced approaches, although accomplishing lipid mobility, fail to achieve complete mobility of incorporated membrane proteins. This is addressed in a novel platform comprising lipid bilayers assembled over buffer-filled, arrays of spherical cap microcavities formed from microsphere template polydimethoxysilane. Prior to bilayer assembly the PDMS is rendered hydrophilic by plasma treatment and the lipid bilayer prepared using Langmuir Blodgett assembly followed by liposome/proteoliposome fusion. Fluorescence Lifetime Correlation Spectroscopy confirmed the pore suspended lipid bilayer exhibits diffusion coefficients comparable to free-standing vesicles in solution. The bilayer modified arrays are highly reproducible and stable over days. As the bilayers are suspended over deep aqueous reservoirs, reconstituted membrane proteins experience an aqueous interface at both membrane interfaces and attain full lateral mobility. Their utility as membrane protein platforms was exemplified in two case studies with proteins of different dimensions in their extracellular and cytoplasmic domains reconstituted into DOPC lipid bilayers; Glycophorin A, and Integrin αIIbβ3. In both cases, the proteins exhibited 100% mobility with high lateral diffusion coefficients. PMID:25798456

  11. Femtosecond laser 3D fabrication of whispering-gallery-mode microcavities

    NASA Astrophysics Data System (ADS)

    Xu, HuaiLiang; Sun, HongBo

    2015-11-01

    Whispering-gallery-mode (WGM) microcavities with high-quality factors and small volumes have attracted intense interests in the past decades because of their potential applications in various research fields such as quantum information, sensing, and optoelectronics. This leads to rapid advance in a variety of processing technologies that can create high-quality WGM micro- cavities. Due to the unique characteristics of femtosecond laser pulses with high peak intensity and ultrashort pulse duration, femtosecond laser shows the ability to carry out ultrahigh precision micromachining of a variety of transparent materials through nonlinear multiphoton absorption and tunneling ionization. This review paper describes the basic principle of femtosecond laser direct writing, and presents an overview of recent progress concerning femtosecond laser three-dimensional (3D) fabrications of optical WGM microcavities, which include the advances in the fabrications of passive and active WGMs microcavities in a variety of materials such as polymer, glass and crystals, as well as in processing the integrated WGM-microcavity device. Lastly, a summary of this dynamic field with a future perspective is given.

  12. Low-threshold indium gallium nitride quantum dot microcavity lasers

    NASA Astrophysics Data System (ADS)

    Woolf, Alexander J.

    Gallium nitride (GaN) microcavities with embedded optical emitters have long been sought after as visible light sources as well as platforms for cavity quantum electrodynamics (cavity QED) experiments. Specifically, materials containing indium gallium nitride (InGaN) quantum dots (QDs) offer an outstanding platform to study light matter interactions and realize practical devices, such as on-chip light emitting diodes and nanolasers. Inherent advantages of nitride-based microcavities include low surface recombination velocities, enhanced room-temperature performance (due to their high exciton binding energy, as high as 67 meV for InGaN QDs), and emission wavelengths in the blue region of the visible spectrum. In spite of these advantages, several challenges must be overcome in order to capitalize on the potential of this material system. Such diffculties include the processing of GaN into high-quality devices due to the chemical inertness of the material, low material quality as a result of strain-induced defects, reduced carrier recombination effciencies due to internal fields, and a lack of characterization of the InGaN QDs themselves due to the diffculty of their growth and therefore lack of development relative to other semiconductor QDs. In this thesis we seek to understand and address such issues by investigating the interaction of light coupled to InGaN QDs via a GaN microcavity resonator. Such coupling led us to the demonstration of the first InGaN QD microcavity laser, whose performance offers insights into the properties and current limitations of the nitride materials and their emitters. This work is organized into three main sections. Part I outlines the key advantages and challenges regarding indium gallium nitride (InGaN) emitters embedded within gallium nitride (GaN) optical microcavities. Previous work is also discussed which establishes context for the work presented here. Part II includes the fundamentals related to laser operation, including the

  13. Mechanism of directional emission from a peanut-shaped microcavity

    SciTech Connect

    Shu Fangjie; Zou Changling; Sun Fangwen; Xiao Yunfeng

    2011-05-15

    Collimated directional emission is essentially required for an asymmetric resonant cavity. In this paper, we theoretically investigate a type of peanut-shaped microcavity which can support highly directional emission with a beam divergence as small as 2.5 deg. The mechanism of the collimated emission of this type of peanut-shaped microcavity is explained with a short-term ray trajectory. Moreover, the explanations are also confirmed by a numerical wave simulation. This extremely narrow divergence of the emission holds great potential in highly collimated lasing from on-chip microcavities.

  14. Multi-directional ultra-high sensitive pressure sensor based on the integration of optimized double 60° bend waveguides and modified center-defect photonic crystal microcavity

    NASA Astrophysics Data System (ADS)

    Zhou, Jian; Yang, Daquan; Tian, Huiping; Huang, Lijun; Zhang, Pan; Ji, Yuefeng

    2015-06-01

    In the previous work [1], we have proposed a method to realize multi-directional pressure sensor. This follow-up work provides an optimized structure design based on the integration of double 60° bend waveguides and modified center-defect photonic crystal microcavity to further improve sensitivity. By applying two-dimensional finite difference time domain technologies (2D-FDTD) and finite-element methods (FEM), we systematically investigate the variations of optical properties under applied pressure. Linear relationships between the resonant wavelength shift and the applied pressure are obtained in three directions. The ultra-high sensitivities and the low minimum detectable pressure in longitudinal, transverse and upright directions are 39.7 nm/μN and 1.08 nN, 30.20 nm/μN and 1.43 nN, and 0.12 nm/nN and 0.36 nN respectively.

  15. A small mode volume tunable microcavity: Development and characterization

    NASA Astrophysics Data System (ADS)

    Greuter, Lukas; Starosielec, Sebastian; Najer, Daniel; Ludwig, Arne; Duempelmann, Luc; Rohner, Dominik; Warburton, Richard J.

    2014-09-01

    We report the realization of a spatially and spectrally tunable air-gap Fabry-Pérot type microcavity of high finesse and cubic-wavelength-scale mode volume. These properties are attractive in the fields of opto-mechanics, quantum sensing, and foremost cavity quantum electrodynamics. The major design feature is a miniaturized concave mirror with atomically smooth surface and radius of curvature as low as 10 μm produced by CO2 laser ablation of fused silica. We demonstrate excellent mode-matching of a focussed laser beam to the microcavity mode and confirm from the frequencies of the resonator modes that the effective optical radius matches the physical radius. With these small radii, we demonstrate wavelength-size beam waists. We also show that the microcavity is sufficiently rigid for practical applications: in a cryostat at 4 K, the root-mean-square microcavity length fluctuations are below 5 pm.

  16. Radiative rate modification in CdSe quantum dot-coated microcavity

    NASA Astrophysics Data System (ADS)

    Veluthandath, Aneesh V.; Bisht, Prem B.

    2015-12-01

    Whispering gallery modes (WGMs) of the microparticles with spherical or cylindrical symmetry have exceptionally high quality factors and small mode volume. Quantum dots (QDs) are zero dimensional systems with variable band gap as well as luminescent properties with applications in photonics. In this paper, the WGMs have been observed in the luminescence spectra of CdSe QD-coated single silica microspheres. Theoretical estimations of variation of resonance frequency, electric field, and Q-values have been done for a multilayer coating of QDs on silica microspheres. Observed WGMs have been identified for their mode number and polarization using Mie theory. Broadening of modes due to material absorption has been observed. Splitting of WGMs has also been observed due to coherent coupling of counter propagating waves in the microcavity due to the presence of QDs. At room temperature, the time-resolved study indicates the modification of the radiative rate due to coupling of WGMs of the microcavity-QD hybrid system.

  17. Radiative rate modification in CdSe quantum dot-coated microcavity

    SciTech Connect

    Veluthandath, Aneesh V.; Bisht, Prem B.

    2015-12-21

    Whispering gallery modes (WGMs) of the microparticles with spherical or cylindrical symmetry have exceptionally high quality factors and small mode volume. Quantum dots (QDs) are zero dimensional systems with variable band gap as well as luminescent properties with applications in photonics. In this paper, the WGMs have been observed in the luminescence spectra of CdSe QD-coated single silica microspheres. Theoretical estimations of variation of resonance frequency, electric field, and Q-values have been done for a multilayer coating of QDs on silica microspheres. Observed WGMs have been identified for their mode number and polarization using Mie theory. Broadening of modes due to material absorption has been observed. Splitting of WGMs has also been observed due to coherent coupling of counter propagating waves in the microcavity due to the presence of QDs. At room temperature, the time-resolved study indicates the modification of the radiative rate due to coupling of WGMs of the microcavity-QD hybrid system.

  18. Dispersion engineering for vertical microcavities using subwavelength gratings.

    PubMed

    Wang, Zhaorong; Zhang, Bo; Deng, Hui

    2015-02-20

    We show that the energy-momentum dispersion of a vertical semiconductor microcavity can be modified by design using a high-index-contrast subwavelength grating (SWG) as a cavity mirror. We analyze the angular dependence of the reflection phase of the SWG to illustrate the principles of dispersion engineering. We show examples of engineered dispersions such as ones with much reduced or increased energy density of states and one with a double-well-shaped dispersion. This method of dispersion engineering is compatible with maintaining a high cavity quality factor and incorporating fully protected active media inside the cavity, thus enabling the creation of new types of cavity quantum electrodynamics systems. PMID:25763957

  19. Precision laser-based decontamination of microcavities

    NASA Astrophysics Data System (ADS)

    Durbin, S. M.; Deshmukh, A. V.; Brooks, T. D.; van de Burgt, L. J.

    1998-05-01

    The removal of oil-based contaminants from microcavities with narrow apertures and comparatively long axial dimensions presents a number of challenges in an industrial production line environment. Traditional solvent-based approaches are costly to implement, inefficient in cleaning such microcavity geometries, and increasingly unacceptable from an environmental standpoint. An attractive alternative is to employ high-energy laser pulses to selectively remove the contaminants without introducing damage to the component undergoing the cleaning procedure. This paper will present results of initial ablation trials on example industrial oil-based organic contaminants whose residues within microcavities in steel-based components are to be removed. At present, higher order lines from a frequency tripled/quadrupled Nd:YAG laser are used to study the optimum fluence for removal of the oil-based contaminant without inflicting damage to the steel. Absorption spectroscopy of the contaminant fluid indicates that photon wavelengths shorter than ˜370 nm will interact with the material. Initial results show that the required intensity at 355 nm (>25 J/cm 2) also damages the type of steel under investigation, but that exposure to even single pulses at 266 nm (˜100 mJ/cm 2) shows adequate removal of the contaminant without significant damage to the steel. Monitoring of the removal process is achieved through exploitation of the blue fluorescence of the oil-based contaminant that occurs as a result of ultraviolet pumping.

  20. Synthetic holography based on scanning microcavity

    NASA Astrophysics Data System (ADS)

    Di Donato, A.; Farina, M.

    2015-11-01

    Synthetic optical holography (SOH) is an imaging technique, introduced in scanning microscopy to record amplitude and phase of a scattered field from a sample. In this paper, it is described a novel implementation of SOH through a lens-free low-coherence system, based on a scanning optical microcavity. This technique combines the low-coherence properties of the source with the mutual interference of scattered waves and the resonant behavior of a micro-cavity, in order to realize a high sensitive imaging system. Micro-cavity is compact and realized by approaching a cleaved optical fiber to the sample. The scanning system works in an open-loop configuration without the need for a reference wave, usually required in interferometric systems. Measurements were performed over calibration samples and a lateral resolution of about 1 μm is achieved by means of an optical fiber with a Numerical Aperture (NA) equal to 0.1 and a Mode Field Diameter (MDF) of 5.6 μm.

  1. Integrated waveguide-DBR microcavity opto-mechanical system.

    PubMed

    Pruessner, Marcel W; Stievater, Todd H; Khurgin, Jacob B; Rabinovich, William S

    2011-10-24

    Cavity opto-mechanics exploits optical forces acting on mechanical structures. Many opto-mechanics demonstrations either require extensive alignment of optical components for probing and measurement, which limits the number of opto-mechanical devices on-chip; or the approaches limit the ability to control the opto-mechanical parameters independently. In this work, we propose an opto-mechanical architecture incorporating a waveguide-DBR microcavity coupled to an in-plane micro-bridge resonator, enabling large-scale integration on-chip with the ability to individually tune the optical and mechanical designs. We experimentally characterize our device and demonstrate mechanical resonance damping and amplification, including the onset of coherent oscillations. The resulting collapse of the resonance linewidth implies a strong increase in effective mechanical quality-factor, which is of interest for high-resolution sensing. PMID:22109043

  2. High-Q contacted ring microcavities with scatterer-avoiding “wiggler” Bloch wave supermode fields

    SciTech Connect

    Liu, Yangyang Popović, Miloš A.

    2014-05-19

    High-Q ring resonators with contacts to the waveguide core provide a versatile platform for various applications in chip-scale optomechanics, thermo-, and electro-optics. We propose and demonstrate azimuthally periodic contacted ring resonators based on multi-mode Bloch matching that support contacts on both the inner and outer radius edges with small degradation to the optical quality factor (Q). Radiative coupling between degenerate modes of adjacent radial spatial order leads to imaginary frequency (Q) splitting and a scatterer avoiding high-Q “wiggler” supermode field. We experimentally measure Qs up to 258 000 in devices fabricated in a silicon device layer on buried oxide undercladding and up to 139 000 in devices fully suspended in air using an undercut step. Wiggler supermodes are true modes of the microphotonic system that offer additional degrees of freedom in electrical, thermal, and mechanical design.

  3. Quantum-dot-induced phase shift in a pillar microcavity

    SciTech Connect

    Young, A. B.; Hu, C. Y.; Rarity, J. G.; Oulton, R.; Thijssen, A. C. T.; Schneider, C.; Reitzenstein, S.; Kamp, M.; Hoefling, S.; Worschech, L.; Forchel, A.

    2011-07-15

    We perform high-resolution reflection spectroscopy of a quantum dot resonantly coupled to a pillar microcavity. We show the change in reflectivity as the quantum dot is tuned through the cavity resonance and measure the quantum-dot-induced phase shift using an ultrastable interferometer. The macroscopic phase shift we measure could be extended to the study of charged quantum dot pillar microcavity systems, where it could be exploited to realize a high-efficiency spin photon interface for hybrid quantum information schemes.

  4. Flip-chip light emitting diode with resonant optical microcavity

    DOEpatents

    Gee, James M.; Bogart, Katherine H.A.; Fischer, Arthur J.

    2005-11-29

    A flip-chip light emitting diode with enhanced efficiency. The device structure employs a microcavity structure in a flip-chip configuration. The microcavity enhances the light emission in vertical modes, which are readily extracted from the device. Most of the rest of the light is emitted into waveguided lateral modes. Flip-chip configuration is advantageous for light emitting diodes (LEDs) grown on dielectric substrates (e.g., gallium nitride LEDs grown on sapphire substrates) in general due to better thermal dissipation and lower series resistance. Flip-chip configuration is advantageous for microcavity LEDs in particular because (a) one of the reflectors is a high-reflectivity metal ohmic contact that is already part of the flip-chip configuration, and (b) current conduction is only required through a single distributed Bragg reflector. Some of the waveguided lateral modes can also be extracted with angled sidewalls used for the interdigitated contacts in the flip-chip configuration.

  5. Ultraviolet light detection using an optical microcavity.

    PubMed

    Harker, Audrey; Mehrabani, Simin; Armani, Andrea M

    2013-09-01

    Ultraviolet (UV) light exposure is connected to both physical and psychological diseases. As such, there is significant interest in developing sensors that can detect UV light in the mW/cm2 intensity range with a high signal-to-noise ratio. In this Letter, we demonstrate a UV sensor based on a silica integrated optical microcavity that has a linear operating response in both the forward and backward directions from 14 to 53 mW/cm2. The sensor response agrees with the developed predictive theory based on a thermodynamic model. Additionally, the signal-to-noise ratio is above 100 at physiologically relevant intensity levels. PMID:23988974

  6. Optical bistability in semiconductor microcavities

    SciTech Connect

    Baas, A.; Karr, J.Ph.; Giacobino, E.; Eleuch, H.

    2004-02-01

    We report the observation of polaritonic bistability in semiconductor microcavities in the strong-coupling regime. The origin of bistability is the polariton-polariton interaction, which gives rise to a Kerr-like nonlinearity. The experimental results are in good agreement with a simple model taking transverse effects into account.

  7. Recyclable optical microcavities for label-free sensing

    NASA Astrophysics Data System (ADS)

    Hunt, Heather K.; Armani, Andrea M.

    2011-10-01

    High-sensitivity, label-free biosensors, such as optical microcavities, have shown tremendous potential in medical diagnostics, environmental monitoring, and food safety evaluation, particularly when paired with a biochemical recognition element that grants high specificity towards a target of interest. Their primary limitation is that these systems are single-use, unless the recognition element can be regenerated. Therefore, the ability to selectively functionalize the optical microcavity for a specific target molecule and then recycle the system, without degrading device performance, is extremely important. Here, we present a bioconjugation strategy that not only imparts specificity to optical microcavities, but also allows for biosensor recycling. In this approach, we selectively functionalize the surface of silica microtoroids with a biotin recognition element. We then use a non-destructive O2 plasma treatment to remove the surface chemistry, refresh the recognition element, and recycle the device. The surface chemistry and optical performance of the functionalized and recycled devices are characterized by microcavity analysis, and typical spectroscopic techniques, respectively. The resulting devices can be recycled several times without performance degradation, and show high density surface coverage of biologically active recognition elements. This work represents one of the first examples of a recyclable, bioconjugation strategy for optical microtoroid resonators.

  8. Tuning the resonance of a photonic crystal microcavity with an AFM probe.

    PubMed

    Märki, Iwan; Salt, Martin; Herzig, Hans Peter

    2006-04-01

    We present theoretical and experimental results on switching and tuning of a two-dimensional photonic crystal resonant microcavity by means of a silicon AFM tip, probing the highly localized optical field in the vicinity of the cavity. On-off switching and modulation of the transmission signal in the kHz range is achieved by bringing an AFM tip onto the center of the microcavity, inducing a damping effect on the transmission resonance. Tuning of the resonant wavelength in the order of several nanometers becomes possible by inserting the AFM tip into one of the holes of the Bragg mirror forming the microcavity in the propagation direction. PMID:19516436

  9. Fabrication and optical properties of non-polar III-nitride air-gap distributed Bragg reflector microcavities

    SciTech Connect

    Tao, Renchun Kako, Satoshi; Arita, Munetaka; Arakawa, Yasuhiko

    2013-11-11

    Using the thermal decomposition technique, non-polar III-nitride air-gap distributed Bragg reflector (DBR) microcavities (MCs) with a single quantum well have been fabricated. Atomic force microscopy reveals a locally smooth DBR surface, and room-temperature micro-photoluminescence measurements show cavity modes. There are two modes per cavity due to optical birefringence in the non-polar MCs, and a systematic cavity mode shift with cavity thickness was also observed. Although the structures consist of only 3 periods (top) and 4 periods (bottom), a quality factor of 1600 (very close to the theoretical value of 2100) reveals the high quality of the air-gap DBR MCs.

  10. Strong light-matter coupling in bulk GaN-microcavities with double dielectric mirrors fabricated by two different methods

    SciTech Connect

    Reveret, F.; Disseix, P.; Vasson, A.; Leymarie, J.; Bejtka, K.; Edwards, P. R.; Martin, R. W.; Chenot, S.; Sellers, I. R.; Duboz, J. Y.; Leroux, M.; Semond, F.

    2010-08-15

    Two routes for the fabrication of bulk GaN microcavities embedded between two dielectric mirrors are described, and the optical properties of the microcavities thus obtained are compared. In both cases, the GaN active layer is grown by molecular beam epitaxy on (111) Si, allowing use of selective etching to remove the substrate. In the first case, a three period Al{sub 0.2}Ga{sub 0.8}N/AlN Bragg mirror followed by a {lambda}/2 GaN cavity are grown directly on the Si. In the second case, a crack-free 2 {mu}m thick GaN layer is grown, and progressively thinned to a final thickness of {lambda}. Both devices work in the strong coupling regime at low temperature, as evidenced by angle-dependent reflectivity or transmission experiments. However, strong light-matter coupling in emission at room temperature is observed only for the second one. This is related to the poor optoelectronic quality of the active layer of the first device, due to its growth only 250 nm above the Si substrate and its related high defect density. The reflectivity spectra of the microcavities are well accounted for by using transfer matrix calculations.

  11. Lasing spiral and square-shaped optical microcavities

    NASA Astrophysics Data System (ADS)

    Chern, Grace D.

    Optical microcavities, which confine light to small dimensions by total internal reflection (TIR), possess unique characteristics that depend on its morphology. The following dissertation presents experimental results from two-dimensional optical microcavities of various cross-sectional shapes. This includes a novel design, specifically a spiral-shaped InGaN multiple-quantum well microcavity, which is the first known microdisk device to produce unidirectional lasing emission from a single output beam when selectively optically-excited with a ring-shaped beam. The spiral microcavities also perform successfully under pulsed as well as continuous-wave current-injection conditions. Furthermore, the output intensity of the spiral microlaser is shown to increase with the addition of semicircle-based microdisks, which serve as optical amplifiers. Square-shaped dye-doped polymer micro-pillars are also examined which could be useful as add/drop filters for wavelength-division-multiplexing. Lasing emission is detected from the square corners due to completely TIR-confined modes which correspond to ray orbits with an incident angle theta inc at or near 45°. Additionally, surprising strong emission from the sidewalls is observed, which is associated with modes that are only partially TIR-confined but still have a high enough reflection coefficient to be sustained.

  12. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    PubMed Central

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-01-01

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. PMID:26901199

  13. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing.

    PubMed

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-01-01

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF₂ microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. PMID:26901199

  14. Microcavity-Integrated Graphene Photodetector

    PubMed Central

    2012-01-01

    There is an increasing interest in using graphene1,2 for optoelectronic applications.3−19 However, because graphene is an inherently weak optical absorber (only ≈2.3% absorption), novel concepts need to be developed to increase the absorption and take full advantage of its unique optical properties. We demonstrate that by monolithically integrating graphene with a Fabry-Pérot microcavity, the optical absorption is 26-fold enhanced, reaching values >60%. We present a graphene-based microcavity photodetector with responsivity of 21 mA/W. Our approach can be applied to a variety of other graphene devices, such as electro-absorption modulators, variable optical attenuators, or light emitters, and provides a new route to graphene photonics with the potential for applications in communications, security, sensing and spectroscopy. PMID:22563791

  15. Fermi resonance in optical microcavities

    NASA Astrophysics Data System (ADS)

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Chil-Min

    2015-04-01

    Fermi resonance is a phenomenon of quantum mechanical superposition, which most often occurs between normal and overtone modes in molecular systems that are nearly coincident in energy. We find that scarred resonances in deformed dielectric microcavities are the very phenomenon of Fermi resonance, that is, a pair of quasinormal modes interact with each other due to coupling and a pair of resonances are generated through an avoided resonance crossing. Then the quantum number difference of a pair of quasinormal modes, which is a consequence of quantum mechanical superposition, equals periodic orbits, whereby the resonances are localized on the periodic orbits. We derive the relation between the quantum number difference and the periodic orbits and confirm it in an elliptic, a rectangular, and a stadium-shaped dielectric microcavity.

  16. Low Dimensional Polariton Systems in Subwavelength-Grating Based Microcavities

    NASA Astrophysics Data System (ADS)

    Zhang, Bo

    Semiconductor microcavity exciton-polaritons have recently emerged as a unique, open system for studying non-equilibrium quantum order. Macroscopic quantum phenomenon, Bose-Einstein condensation, has been realized and observed in two dimensional polariton systems utilizing the traditional distributed-Bragg-reflector based samples. Such foundational work on two-dimensional systems has inspired theoretical schemes for polariton-based quantum circuits, quantum light sources and novel quantum phases. Experimental implementation of these schemes requires the control, confinement and coupling of polariton systems, which still remain challenging in conventional microcavity structures. In this thesis, we use the sub-wavelength grating-based microcavities to demonstrate confinement and coupling for the polariton systems. We demonstrated a zero-dimensional polariton device in the sub-wavelength grating-based microcavity. Efficient confinement has been realized in such unconventional microcavity. These confinement features have also been observed in the spectroscopic characterization with discretized energy levels from the device. In addition, the polaritons are highly linear polarized, which is unique to the sub-wavelength grating based devices. The establishment of the polariton lasing/condensation was with non-linear increase of the emission intensity, line-width narrowing and continuous energy shift. Single-mode lasing of polaritons was also demonstrated for the first time. Following the work of single zero-dimensional polariton device, we demonstrated that the coupling among multiple zero-dimensional polariton quantum devices could be readily achieved, leading to de-coupled, coupled and quasi-one-dimensional polariton systems. These coupling effects were controlled and realized by design of the tethering patterns around the sub-wavelength grating based devices. Such devices enable advanced mode engineering and provide the building blocks for polariton-based quantum

  17. Variable deflection response of sensitive CNT-on-fiber artificial hair sensors from CNT synthesis in high aspect ratio microcavities

    NASA Astrophysics Data System (ADS)

    Slinker, Keith; Maschmann, Matthew R.; Kondash, Corey; Severin, Benjamin; Phillips, David; Dickinson, Benjamin T.; Reich, Gregory; Baur, Jeff

    2015-03-01

    Crickets, locusts, bats, and many other animals detect changes in their environment with distributed arrays of flow-sensitive hairs. Here we discuss the fabrication and characterization of a relatively new class of pore-based, artificial hair sensors that take advantage of the mechanical properties of structural microfibers and the electromechanical properties of self-aligned carbon nanotube arrays to rapidly transduce changes in low speed air flow. The radially aligned nanotubes are able to be synthesized along the length of the fibers inside the high aspect ratio cavity between the fiber surface and the wall of a microcapillary pore. The growth self-positions the fibers within the capillary and forms a conductive path between detection electrodes. As the hair is deflected, nanotubes are compressed to produce a typical resistance change of 1-5% per m/s of air speed which we believe are the highest sensitivities reported for air velocities less than 10 m/s. The quasi-static response of the sensors to point loads is compared to that from the distributed loads of air flow. A plane wave tube is used to measure their dynamic response when perturbed at acoustic frequencies. Correlation of the nanotube height profile inside the capillary to a diffusion transport model suggests that the nanotube arrays can be controllably tapered along the fiber. Like their biological counterparts, many applications can be envisioned for artificial hair sensors by tailoring their individual response and incorporating them into arrays for detecting spatio-temporal flow patterns over rigid surfaces such as aircraft.

  18. Ultra High Quality Factor Microtoroid for Chemical and Biomedical Sensing Applications

    NASA Astrophysics Data System (ADS)

    Kim, Woosung

    Optical whispering gallery mode (WGM) microcavities have drawn attentions in various types of sensing, such as chemical- and bio-sensing. Even though various types of microcavity geometries have been investigated, research about on-chip WGM toroidal resonator has been discontinued for the sensing applications in aquatic environment. The strong benefits of the microtoroid are ultra-high-Q and small mode volume leading to high sensitivity to small change of environment, surrounding media refractive index change or light scatterer induced effective refractive index change. By using this ultra high-Q WGM resonator, radius >75nm polystyrene nanoparticle are detected in aquatic environment. In addition to polystyrene nanoparticle sensing, individual synthetic hemozoin crystals are detected and its size is measured. The hemozoin crystal sensing ultimately leads to malaria infection diagnose. A sol-gel method fabricated microlaser, co-work with Lina He, extended the sensing capability, detecting >30nm radius polystyrene nanoparticle. Since the water experiment is challenging and tackling the difficulty is main task, theoretical investigations are performed about WGM resonance quality factor, resonator mode volume, and noise to minimum detectable particle size. The research described in this dissertation will shed light on advanced chemical- and bio-sensor developments.

  19. Pixel-level plasmonic microcavity infrared photodetector

    PubMed Central

    Jing, You Liang; Li, Zhi Feng; Li, Qian; Chen, Xiao Shuang; Chen, Ping Ping; Wang, Han; Li, Meng Yao; Li, Ning; Lu, Wei

    2016-01-01

    Recently, plasmonics has been central to the manipulation of photons on the subwavelength scale, and superior infrared imagers have opened novel applications in many fields. Here, we demonstrate the first pixel-level plasmonic microcavity infrared photodetector with a single quantum well integrated between metal patches and a reflection layer. Greater than one order of magnitude enhancement of the peak responsivity has been observed. The significant improvement originates from the highly confined optical mode in the cavity, leading to a strong coupling between photons and the quantum well, resulting in the enhanced photo-electric conversion process. Such strong coupling from the localized surface plasmon mode inside the cavity is independent of incident angles, offering a unique solution to high-performance focal plane array devices. This demonstration paves the way for important infrared optoelectronic devices for sensing and imaging. PMID:27181111

  20. Pixel-level plasmonic microcavity infrared photodetector.

    PubMed

    Jing, You Liang; Li, Zhi Feng; Li, Qian; Chen, Xiao Shuang; Chen, Ping Ping; Wang, Han; Li, Meng Yao; Li, Ning; Lu, Wei

    2016-01-01

    Recently, plasmonics has been central to the manipulation of photons on the subwavelength scale, and superior infrared imagers have opened novel applications in many fields. Here, we demonstrate the first pixel-level plasmonic microcavity infrared photodetector with a single quantum well integrated between metal patches and a reflection layer. Greater than one order of magnitude enhancement of the peak responsivity has been observed. The significant improvement originates from the highly confined optical mode in the cavity, leading to a strong coupling between photons and the quantum well, resulting in the enhanced photo-electric conversion process. Such strong coupling from the localized surface plasmon mode inside the cavity is independent of incident angles, offering a unique solution to high-performance focal plane array devices. This demonstration paves the way for important infrared optoelectronic devices for sensing and imaging. PMID:27181111

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

    PubMed Central

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

    2015-01-01

    Current bacterial detection techniques are relatively slow, require bulky instrumentation, and usually require some form of specialized training. The gold standard for bacterial detection is culture testing, which can take several days to receive a viable result. Therefore, simpler detection techniques that are both fast and sensitive could greatly improve bacterial detection and identification. Here, we present a new method for the detection of the bacteria Helicobacter hepaticus using whispering-gallery mode (WGM) optical microcavity-based sensors. Due to minimal reflection losses and low material adsorption, WGM-based sensors have ultra-high quality factors, resulting in high-sensitivity sensor devices. In this study, we have shown that bacteria can be non-specifically detected using WGM optical microcavity-based sensors. The minimum detection for the device was 1 × 104 cells/mL, and the minimum time of detection was found to be 750 s. Given that a cell density as low as 1 × 103 cells/mL for Helicobacter hepaticus can cause infection, the limit of detection shown here would be useful for most levels where Helicobacter hepaticus is biologically relevant. This study suggests a new approach for H. hepaticus detection using label-free optical sensors that is faster than, and potentially as sensitive as, standard techniques. PMID:26262647

  2. Photothermal effects in ultra-precisely stabilized tunable microcavities.

    PubMed

    Brachmann, Johannes F S; Kaupp, Hanno; Hänsch, Theodor W; Hunger, David

    2016-09-01

    We study the mechanical stability of a tunable high-finesse microcavity under ambient conditions and investigate light-induced effects that can both suppress and excite mechanical fluctuations. As an enabling step, we demonstrate the ultra-precise electronic stabilization of a microcavity. We then show that photothermal mirror expansion can provide high-bandwidth feedback and improve cavity stability by almost two orders of magnitude. At high intracavity power, we observe self-oscillations of mechanical resonances of the cavity. We explain the observations by a dynamic photothermal instability, leading to parametric driving of mechanical motion. For an optimized combination of electronic and photothermal stabilization, we achieve a feedback bandwidth of 500 kHz and a noise level of 1.1 × 10-13 m rms. PMID:27607722

  3. Tubular optical microcavities of indefinite medium for sensitive liquid refractometers.

    PubMed

    Tang, Shiwei; Fang, Yangfu; Liu, Zhaowei; Zhou, Lei; Mei, Yongfeng

    2016-01-01

    Optical microcavities enable circulated light to intensively interact with a detecting liquid, thus promising high sensitivity in fluidic refractometers. Based on Mie scattering theory, we propose a tubular metamaterial device for liquid sensing, which utilizes anisotropic metamaterials with hyperbolic dispersion called indefinite media (IM). Besides traditional whispering gallery modes (WGMs), such tubular cavities can support surface plasmon polariton (SPP) WGMs, enabling high sensitivity liquid detection. Three configurations of such metamaterial tubes for sensing are discussed: tube-in-liquid, hollow-tube-in-liquid and liquid-in-tube; these are analyzed using numerical formulas and compared with dielectric and metal materials. Compared with traditional dielectric media (DM), the IM tubular cavity exhibits a higher sensitivity (S), which is close to that of a metal tubular cavity. However, compared with metal media, such an IM cavity can achieve higher quality (Q) factors similar to the DM tubular cavity. Therefore, the IM tubular cavity can offer the highest figures of merit (QS) for the sensing performance among the three types of materials. Our results suggest a novel tubular optofluidic device based on metamaterials, which could be useful for liquid refractometers. PMID:26605851

  4. Microcavities coupled to multilevel atoms

    SciTech Connect

    Schmid, Sandra Isabelle; Evers, Joerg

    2011-11-15

    A three-level atom in the {Lambda} configuration coupled to a microcavity is studied. The two transitions of the atom are assumed to couple to different counterpropagating mode pairs in the cavity. We analyze the dynamics both in the strong-coupling and the bad-cavity limits. We find that, compared to a two-level setup, the third atomic state and the additional control field modes crucially modify the system dynamics and enable more advanced control schemes. All results are explained using appropriate dressed-state and eigenmode representations. As potential applications, we discuss optical switching and turnstile operations and detection of particles close to the resonator surface.

  5. Detection of single nanoparticles and lentiviruses using microcavity resonance broadening.

    PubMed

    Shao, Linbo; Jiang, Xue-Feng; Yu, Xiao-Chong; Li, Bei-Bei; Clements, William R; Vollmer, Frank; Wang, Wei; Xiao, Yun-Feng; Gong, Qihuang

    2013-10-18

    A new label-free sensing mechanism is demonstrated experimentally by monitoring the whispering-gallery mode broadening in microcavities. It is immune to both noise from the probe laser and environmental disturbances, and is able to remove the strict requirement for ultra-high-Q mode cavities for sensitive nanoparticle detection. This ability to sense nanoscale objects and biological analytes is particularly crucial for wide applications. PMID:24303524

  6. Extreme output sensitivity to subwavelength boundary deformation in microcavities

    NASA Astrophysics Data System (ADS)

    Ge, Li; Song, Qinghai; Redding, Brandon; Cao, Hui

    2013-02-01

    We demonstrate a generic and robust mechanism that leads to an extreme output sensitivity to a deep subwavelength boundary perturbation in wavelength-scale microcavities. A deformation of the cavity boundary on the order of ten-thousandth of a wavelength may flip the output directions by 180∘, corresponding to a variation of 0.1 nm for a 1-μm-radius cavity. Our analysis based on a perturbation theory reveals that such tiny structural change can cause a strong mixing of nearly degenerate cavity resonances with different angular momenta, and their interference is greatly enhanced to have a radical influence on the far-field pattern. Our finding opens the possibility of utilizing carefully designed wavelength-scale microcavities for fast beam steering and high-resolution detection.

  7. Simulation of J-aggregate microcavity photoluminescence

    NASA Astrophysics Data System (ADS)

    Michetti, Paolo; La Rocca, Giuseppe C.

    2008-05-01

    We have developed a model in order to account for the photoexcitation dynamics of J-aggregate films and strongly coupled J-aggregate microcavities. The J aggregates are described as a disordered Frenkel exciton system in which relaxation occurs due to the presence of a thermal bath of molecular vibrations. The correspondence between the photophysics in J-aggregate films and that in J-aggregate microcavities is obtained by introducing a model polariton wave function mixing cavity photon modes and J-aggregate super-radiant excitons. With the same description of the material properties, we have calculated both absorption and luminescence spectra for the J-aggregate film and the photoluminescence of strongly coupled organic microcavities. The model is able to account for the fast relaxation dynamics in organic microcavities following nonresonant pumping and explains the temperature dependence of the ratio between the upper polariton and the lower polariton luminescence.

  8. Label-free microcavity biosensors: steps towards personalized medicine.

    PubMed

    Amarie, Dragos; Glazier, James A

    2012-01-01

    Personalized medicine has the potential to improve our ability to maintain health and treat disease, while ameliorating continuously rising healthcare costs. Translation of basic research findings to clinical applications within regulatory compliance is required for personalized medicine to become the new foundation for practice of medicine. Deploying even a few of the thousands of potential diagnostic biomarkers identified each year as part of personalized treatment workflows requires clinically efficient biosensor technologies to monitor multiple biomarkers in patients in real time. This paper discusses a critical component of a regulatory system, a microcavity optical biosensor for label-free monitoring of biomolecular interactions at physiologically-relevant concentrations. While most current biosensor research focuses on improving sensitivity, this paper emphasizes other characteristics a biosensor technology requires to be practical in a clinical setting, presenting robust microcavity biosensors which are easy to manufacture and integrate with microfluidics into flexible and redesignable platforms making the microcavity biosensors deployable for continuous monitoring of biomarkers in body fluids in the clinic,  in dense 2D random arrays for high-throughput applications like drug-library screening in interactomics, and of the secretory behavior of single cells in the laboratory. PMID:23443397

  9. Label-Free Microcavity Biosensors: Steps towards Personalized Medicine

    PubMed Central

    Amarie, Dragos; Glazier, James A.

    2012-01-01

    Personalized medicine has the potential to improve our ability to maintain health and treat disease, while ameliorating continuously rising healthcare costs. Translation of basic research findings to clinical applications within regulatory compliance is required for personalized medicine to become the new foundation for practice of medicine. Deploying even a few of the thousands of potential diagnostic biomarkers identified each year as part of personalized treatment workflows requires clinically efficient biosensor technologies to monitor multiple biomarkers in patients in real time. This paper discusses a critical component of a regulatory system, a microcavity optical biosensor for label-free monitoring of biomolecular interactions at physiologically-relevant concentrations. While most current biosensor research focuses on improving sensitivity, this paper emphasizes other characteristics a biosensor technology requires to be practical in a clinical setting, presenting robust microcavity biosensors which are easy to manufacture and integrate with microfluidics into flexible and redesignable platforms making the microcavity biosensors deployable for continuous monitoring of biomarkers in body fluids in the clinic, in dense 2D random arrays for high-throughput applications like drug-library screening in interactomics, and of the secretory behavior of single cells in the laboratory. PMID:23443397

  10. Two-Dimensional Metal–Chalcogenide Films in Tunable Optical Microcavities

    PubMed Central

    2014-01-01

    Integration of quasi-two-dimensional (2D) films of metal–chalcogenides in optical microcavities permits new photonic applications of these materials. Here we present tunable microcavities with monolayer MoS2 or few monolayer GaSe films. We observe significant modification of spectral and temporal properties of photoluminescence (PL): PL is emitted in spectrally narrow and wavelength-tunable cavity modes with quality factors up to 7400; a 10-fold PL lifetime shortening is achieved, a consequence of Purcell enhancement of the spontaneous emission rate. PMID:25375802

  11. Mid-infrared silicon-on-sapphire waveguide coupled photonic crystal microcavities

    SciTech Connect

    Zou, Yi E-mail: swapnajit.chakravarty@omegaoptics.com Chen, Ray T. E-mail: swapnajit.chakravarty@omegaoptics.com; Chakravarty, Swapnajit E-mail: swapnajit.chakravarty@omegaoptics.com

    2015-08-24

    We experimentally demonstrate a photonic crystal (PC) microcavity side coupled to a W1.05 photonic crystal waveguide fabricated in silicon-on-sapphire working in mid-IR regime at 3.43 μm. Using a fixed wavelength laser source, propagation characteristics of PC waveguides without microcavity are characterized as a function of lattice constant to determine the light line position, stop gap, and guided mode transmission behavior. The resonance of an L21 PC microcavity coupled to the W1.05 PCW in the guided mode transmission region is then measured by thermal tuning of the cavity resonance across the source wavelength. Resonance quality factor ∼3500 is measured from the temperature dependency curve.

  12. Signature of Wave Chaos in Spectral Characteristics of Microcavity Lasers.

    PubMed

    Sunada, Satoshi; Shinohara, Susumu; Fukushima, Takehiro; Harayama, Takahisa

    2016-05-20

    We report an experimental investigation on the spectra of fully chaotic and nonchaotic microcavity lasers under continuous-wave operating conditions. It is found that fully chaotic microcavity lasers operate in single mode, whereas nonchaotic microcavity lasers operate in multimode. The suppression of multimode lasing for fully chaotic microcavity lasers is explained by large spatial overlaps of the resonance wave functions that spread throughout the two-dimensional cavity due to the ergodicity of chaotic ray orbits. PMID:27258870

  13. High-quality breast MRI.

    PubMed

    Hendrick, R Edward

    2014-05-01

    Breast magnetic resonance imaging (MRI) demands the competing factors of high spatial resolution, good temporal resolution, high signal-to-noise ratios, and complete bilateral breast coverage. Achieving these competing factors requires modern MRI equipment with high magnetic field strength and homogeneity, high maximum gradient strength with short rise times, dedicated multichannel bilateral breast coils with prone patient positioning, and 3D (volume) gradient-echo MRI pulse sequences with short TR, short TE, high spatial resolution, and reasonably short acquisition times. This article discusses the equipment and pulse sequences needed to achieve high-quality breast MRI and summarizes requirements of the ACR Breast MRI Accreditation Program. PMID:24792656

  14. Microcavity effect using nanoparticles to enhance the efficiency of organic light-emitting diodes.

    PubMed

    Han, Jun Hee; Kim, Do-Hong; Choi, Kyung Cheol

    2015-07-27

    In this paper, in contrast with previously reported approaches, we suggest exploiting a microcavity effect using nanoparticles to improve the optical efficiency of organic light-emitting diodes (OLED). The method to input the nanoparticles inside the OLED device is simple and cost effective by virtue of employing a solution process using a spin coating fabrication method. Titanium dioxide (TiO2) nanoparticles were used to improve the reflection by its high refractive index. In tandem with optimized heights of the organic layers, the increased light reflectance at the anode side, which includes the TiO2 nanoparticle layer, improved the optical efficiency of the OLED device via the microcavity effect. In order to prove that the enhancement of the optical efficiency was due to an enhanced microcavity effect caused by TiO2 nanoparticles, a microcavity simulation was conducted. The electrical characteristics were not affected by the nanoparticles and a clear pixel image was maintained. The results in this paper show that a nanoparticle based microcavity effect can be exploited to enhance the optical efficiency of OLEDs. PMID:26367646

  15. 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.

  16. Superior performance of organic light-emitting diodes with microcavity effect

    NASA Astrophysics Data System (ADS)

    Park, Sang-Geon; Mori, Tatsuo; Wang, Haiying

    2014-12-01

    The electro-optics characteristics of organic light-emitting diodes (OLEDs) with microcavity effect were investigated. The transmittance of the substrate with Ag anode was lower than that of the indium-tin-oxide (ITO) anode due to the opaque characteristics of Ag. The current density of the device with Ag anode was high due to the low sheet resistance of Ag anode. The current efficiency of the device with Ag anode was high due to microcavity structure between Ag anode and Al cathode. Especially, the devices of Ag anode show over 43% higher current efficiency than that of conventional ITO anode. The low transmittance of Ag anode using microcavity effect realized as one kind of Fabry-Perot filters was also verified.

  17. Proposal for high-speed and high-fidelity electron-spin initialization in a negatively charged quantum dot coupled to a microcavity in a weak external magnetic field

    SciTech Connect

    Majumdar, Arka; Lin Ziliang; Faraon, Andrei; Vuckovic, Jelena

    2010-08-15

    We describe a proposal for fast electron-spin initialization in a negatively charged quantum dot coupled to a microcavity without the need for a strong magnetic field. We employ two-photon excitation to access trion states that are spin forbidden by one-photon excitation. Our simulation shows a maximum initialization speed of 1.3 GHz and maximum fidelity of 99.7% with realistic system parameters.

  18. Tuning a microcavity-coupled terahertz laser

    NASA Astrophysics Data System (ADS)

    Castellano, Fabrizio; Bianchi, Vezio; Li, Lianhe; Zhu, Jingxuan; Tredicucci, Alessandro; Linfield, Edmund H.; Giles Davies, A.; Vitiello, Miriam S.

    2015-12-01

    Tunable oscillators are a key component of almost all electronic and photonic systems. Yet, a technology capable of operating in the terahertz (THz)-frequency range and fully suitable for widescale implementation is still lacking. This issue is significantly limiting potential THz applications in gas sensing, high-resolution spectroscopy, hyper-spectral imaging, and optical communications. The THz quantum cascade laser is arguably the most promising solution in terms of output power and spectral purity. In order to achieve reliable, repeatable, and broad tunability, here we exploit the strong coupling between two different cavity mode concepts: a distributed feedback one-dimensional photonic resonator (providing gain) and a mechanically actuated wavelength-size microcavity (providing tuning). The result is a continuously tunable, single-mode emitter covering a 162 GHz spectral range, centered on 3.2 THz. Our source has a few tens of MHz resolution, extremely high differential efficiency, and unprecedented compact and simple design architecture. By unveiling the large potential that lies in this technique, our results provide a robust platform for radically different THz systems exploiting broadly tunable semiconductor lasers.

  19. Tuning a microcavity-coupled terahertz laser

    SciTech Connect

    Castellano, Fabrizio; Bianchi, Vezio; Vitiello, Miriam S.; Li, Lianhe; Zhu, Jingxuan; Linfield, Edmund H.; Giles Davies, A.; Tredicucci, Alessandro

    2015-12-28

    Tunable oscillators are a key component of almost all electronic and photonic systems. Yet, a technology capable of operating in the terahertz (THz)-frequency range and fully suitable for widescale implementation is still lacking. This issue is significantly limiting potential THz applications in gas sensing, high-resolution spectroscopy, hyper-spectral imaging, and optical communications. The THz quantum cascade laser is arguably the most promising solution in terms of output power and spectral purity. In order to achieve reliable, repeatable, and broad tunability, here we exploit the strong coupling between two different cavity mode concepts: a distributed feedback one-dimensional photonic resonator (providing gain) and a mechanically actuated wavelength-size microcavity (providing tuning). The result is a continuously tunable, single-mode emitter covering a 162 GHz spectral range, centered on 3.2 THz. Our source has a few tens of MHz resolution, extremely high differential efficiency, and unprecedented compact and simple design architecture. By unveiling the large potential that lies in this technique, our results provide a robust platform for radically different THz systems exploiting broadly tunable semiconductor lasers.

  20. Threshold reduction by multidimensional photonic confinement in metal-organic microcavities

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Reinhardt, Christoph; Sudzius, Markas; Lyssenko, Vadim G.; Fröb, Hartmut; Leo, Karl

    2014-05-01

    Due to their geometry, optical microcavities allow strong confinement of light between the mirrors and promise single mode operation at lowest possible lasing thresholds. Nevertheless, such devices suffer from losses not only due to parasitic absorption of the active or mirror layers, but especially via outcoupling of leaky and waveguided modes within the active layer. In this work, we present an organic microcavity sandwiched between high quality dielectric distributed Bragg reflectors. A highly conductive silver layer of 40nm thickness is added next to the active layer, leading to the formation of Tamm-Plasmon-Polaritons (TPP), one replacing the original cavity mode and shifting its resonance to the red, another one emerging from the long-wavelength sideband and moving to the blue. To avoid parasitic absorption introduced by such contacts, the silver layer is structured on the micrometer-scale using photolithography, yielding separated areas supporting either original cavity mode or red shifted TPP-resonances. This separation leads to a strong spatial trapping of the modes to only their resonant regions on the sample and can in turn be exploited to achieve complete three-dimensional confinement of photons. In elliptic holes produced in the metal layer, we observe the formation of Mathieu-Modes, leading to a reduction of the lasing threshold by six times. Facilitating triangular cuts in the silver layer, highly confined standing modes develop in the system, allowing a precise optimization of the spatial mode extension and reducing the threshold even further down to one order of magnitude below the threshold of an unstructured organic cavity. These results show that the introduction of absorptive metals, needed for the realization of an electrically driven laser, can in turn be harnessed to improve the characteristics of the device.

  1. Magneto-optical responses of microcavity-integrated graphene photonic crystals in the infrared spectral region

    NASA Astrophysics Data System (ADS)

    Abdi-Ghaleh, Reza; Sattari, Maryam

    2016-09-01

    The magneto-optical responses and photonic band gap properties of the microcavity-integrated graphene photonic crystals were numerically studied. The structure consists of a graphene sheet embedded between two mirror symmetric Bragg reflectors, under the influence of an external static magnetic field. The properties of the microcavity resonance mode were investigated, considering the right- and left-handed circular polarization transmission coefficients and their phases, together with the Faraday rotation angle and ellipticity of the output light. The effects of the repetition number of the Bragg reflectors, thickness of the microcavity central layer and refractive indices of the graphene adjacent layers were considered. The obtained results revealed that a pure linear polarized output light with no ellipticity and high transmittance enhanced Faraday rotation can be achieved. These results can be utilized in designing a variety of graphene based photonic devices and magneto-optical integrated elements, such as miniaturized isolators or circulators.

  2. Theory and measurement of the soliton self-frequency shift and efficiency in optical microcavities.

    PubMed

    Yi, Xu; Yang, Qi-Fan; Yang, Ki Youl; Vahala, Kerry

    2016-08-01

    Dissipative Kerr cavity solitons experience a so-called self-frequency shift (SFS) as a result of Raman interactions. The frequency shift has been observed in several microcavity systems. The Raman process has also been shown numerically to influence the soliton pumping efficiency. Here, a perturbed Lagrangian approach is used to derive simple analytical expressions for the SFS and the soliton efficiency. The predicted dependences of these quantities on soliton pulse width are compared with measurements in a high-Q silica microcavity. The Raman time constant in silica is also inferred. Analytical expressions for the Raman SFS and soliton efficiency greatly simplify the prediction of soliton behavior over a wide range of microcavity platforms. PMID:27472583

  3. Porous silicon microcavities: synthesis, characterization, and application to photonic barcode devices

    NASA Astrophysics Data System (ADS)

    Ramiro-Manzano, Fernando; Fenollosa, Roberto; Xifré-Pérez, Elisabet; Garín, Moises; Meseguer, Francisco

    2012-09-01

    We have recently developed a new type of porous silicon we name as porous silicon colloids. They consist of almost perfect spherical silicon nanoparticles with a very smooth surface, able to scatter (and also trap) light very efficiently in a large-span frequency range. Porous silicon colloids have unique properties because of the following: (a) they behave as optical microcavities with a high refractive index, and (b) the intrinsic photoluminescence (PL) emission is coupled to the optical modes of the microcavity resulting in a unique luminescence spectrum profile. The PL spectrum constitutes an optical fingerprint identifying each particle, with application for biosensing. In this paper, we review the synthesis of silicon colloids for developing porous nanoparticles. We also report on the optical properties with special emphasis in the PL emission of porous silicon microcavities. Finally, we present the photonic barcode concept.

  4. Porous silicon microcavities: synthesis, characterization, and application to photonic barcode devices

    PubMed Central

    2012-01-01

    We have recently developed a new type of porous silicon we name as porous silicon colloids. They consist of almost perfect spherical silicon nanoparticles with a very smooth surface, able to scatter (and also trap) light very efficiently in a large-span frequency range. Porous silicon colloids have unique properties because of the following: (a) they behave as optical microcavities with a high refractive index, and (b) the intrinsic photoluminescence (PL) emission is coupled to the optical modes of the microcavity resulting in a unique luminescence spectrum profile. The PL spectrum constitutes an optical fingerprint identifying each particle, with application for biosensing. In this paper, we review the synthesis of silicon colloids for developing porous nanoparticles. We also report on the optical properties with special emphasis in the PL emission of porous silicon microcavities. Finally, we present the photonic barcode concept. PMID:22943136

  5. Microcavity-Integrated Carbon Nanotube Photodetectors.

    PubMed

    Liang, Shuang; Ma, Ze; Wu, Gongtao; Wei, Nan; Huang, Le; Huang, Huixin; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2016-07-26

    Carbon nanotubes (CNTs) are considered to be highly promising nanomaterials for multiwavelength, room-temperature infrared detection applications. Here, we demonstrate a single-tube diode photodetector monolithically integrated with a Fabry-Pérot microcavity. A ∼6-fold enhanced optical absorption can be achieved, because of the confined effect of the designed optical mode. Furthermore, taking advantage of Van-Hove-singularity band structures in CNTs, we open the possibility of developing chirality-specific (n,m) CNT-film-based signal detectors. Utilizing a concept of the "resonance and off-resonance" cavity, we achieved cavity-integrated chirality-sorted CNT-film detectors working at zero bias and resonance-allowed mode, for specific target signal detection. The detectors exhibited a higher suppression ratio until a power density of 0.07 W cm(-2) and photocurrent of 5 pA, and the spectral full width at half-maximum is ∼33 nm at a signal wavelength of 1200 nm. Further, with multiple array detectors aiming at different target signals integrated on a chip, a multiwavelength signal detector system can be expected to have applications in the fields of monitoring, biosensing, color imaging, signal capture, and on-chip or space information transfers. The approach can also bring other nanomaterials into on-chip or information optoelectronics, regardless of the available doping polarity. PMID:27379375

  6. Optically active silica and polymeric materials for microcavity lasers and sensors

    NASA Astrophysics Data System (ADS)

    Armani, A. M.; Deka, N.; Mehrabani, S.; Shi, C.; Maker, A.; Lee, M.; Kovach, A.; Gungor, E.; Kuo, K.; Diep, V.

    2015-03-01

    Silica and silica-doped high quality factor (Q) optical resonators have demonstrated ultra-low threshold lasers based on numerous mechanisms (eg rare earth dopants, Raman). To date, the key focus has been on maintaining a high Q, as that determines the lasing threshold and linewidth. However, equally important criteria are lasing efficiency and wavelength. These parameters are governed by the material, not the cavity Q. Therefore, to fully address this challenge, it is necessary to develop new materials. We have synthesized a suite of silica and polymeric materials with nanoparticle and rare-earth dopants to enable the development of microcavity lasers with emission from the near-IR to the UV. Additionally, the efficiencies and thresholds of many of these devices surpass the previous work. Specifically, the silica sol-gel lasers are co- and tri-doped with metal nanoparticles (eg Ti, Al) and rare-earth materials (eg Yb, Nb, Tm) and are fabricated using conventional micro/nanofabrication methods. The intercalation of the metal in the silica matrix reduces the clustering of the rare-earth ions and reduces the phonon energy of the glass, improving efficiency and overall device performance. Additionally, the silica Raman gain coefficient is enhanced due to the inclusion of the metal nanoparticles, which results in a lower threshold and a higher efficiency silica Raman laser. Finally, we have synthesized several polymer films doped with metal (eg Au, Ag) nanoparticles and deposited them on the surface of our microcavity devices. By pumping on the plasmonic resonant wavelength of the particle, we are able to achieve plasmonic-enhanced upconversion lasing.

  7. Fabrication of silica ultra high quality factor microresonators.

    PubMed

    Maker, Ashley J; Armani, Andrea M

    2012-01-01

    Whispering gallery resonant cavities confine light in circular orbits at their periphery. The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.(3-7) The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q>100 million). However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment. Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment. PMID:22805153

  8. Open-access microcavities for chemical sensing.

    PubMed

    Vallance, Claire; Trichet, Aurelien A P; James, Dean; Dolan, Philip R; Smith, Jason M

    2016-07-01

    The recent development of open-access optical microcavities opens up a number of intriguing possibilities in the realm of chemical sensing. We provide an overview of the different possible sensing modalities, with examples of refractive index sensing, optical absorption measurements, and optical tracking and trapping of nanoparticles. The extremely small mode volumes within an optical microcavity allow very small numbers of molecules to be probed: our current best detection limits for refractive index and absorption sensing are around 10(5) and 10(2) molecules, respectively, with scope for further improvements in the future. PMID:27242174

  9. Open-access microcavities for chemical sensing

    NASA Astrophysics Data System (ADS)

    Vallance, Claire; Trichet, Aurelien A. P.; James, Dean; Dolan, Philip R.; Smith, Jason M.

    2016-07-01

    The recent development of open-access optical microcavities opens up a number of intriguing possibilities in the realm of chemical sensing. We provide an overview of the different possible sensing modalities, with examples of refractive index sensing, optical absorption measurements, and optical tracking and trapping of nanoparticles. The extremely small mode volumes within an optical microcavity allow very small numbers of molecules to be probed: our current best detection limits for refractive index and absorption sensing are around 105 and 102 molecules, respectively, with scope for further improvements in the future.

  10. Optofluidic microcavities: Dye-lasers and biosensors

    PubMed Central

    Chen, Y.; Lei, L.; Zhang, K.; Shi, J.; Wang, L.; Li, H.; Zhang, X. M.; Wang, Y.; Chan, H. L. W.

    2010-01-01

    Optofluidic microcavities are integrated elements of microfluidics that can be explored for a large variety of applications. In this review, we first introduce the physics basis of optical microcavities and microflow control. Then, we describe four types of optofluidic dye lasers developed so far based on both simple and advanced device fabrication technologies. To illustrate the application potential of such devices, we present two types of laser intracavity measurements for chemical solution and single cell analyses. In addition, the possibility of single molecule detection is discussed. All these recent achievements demonstrated the great importance of the topics in biology and several other disciplines. PMID:24753719

  11. Electrically-detected ESR in silicon nanostructures inserted in microcavities

    SciTech Connect

    Bagraev, Nikolay; Danilovskii, Eduard; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna; Gehlhoff, Wolfgang; Mashkov, Vladimir; Romanov, Vladimir

    2014-02-21

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ- barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance, with internal GHz Josephson emission within frameworks of the normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane.

  12. Electrically-detected ESR in silicon nanostructures inserted in microcavities

    NASA Astrophysics Data System (ADS)

    Bagraev, Nikolay; Danilovskii, Eduard; Gehlhoff, Wolfgang; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna; Mashkov, Vladimir; Romanov, Vladimir

    2014-02-01

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ- barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance, with internal GHz Josephson emission within frameworks of the normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane.

  13. Modified Photoluminescence by Silicon-Based One-Dimensional Photonic Crystal Microcavities

    NASA Astrophysics Data System (ADS)

    Chen, San; Qian, Bo; Wei, Jun-Wei; Chen, Kun-Ji; Xu, Jun; Li, Wei; Huang, Xin-Fan

    2005-01-01

    Photoluminescence (PL) from one-dimensional photonic band structures is investigated. The doped photonic crystal with microcavities are fabricated by using alternating hydrogenated amorphous silicon nitride (a-SiNx:H/a-SiNy:H) layers in a plasma enhanced chemical vapour deposition (PECVD) chamber. It is observed that microcavities strongly modify the PL spectra from active hydrogenated amorphous silicon nitride (a-SiNz:H) thin film. By comparison, the wide emission band width 208 nm is strongly narrowed to 11 nm, and the resonant enhancement of the peak PL intensity is about two orders of magnitude with respect to the emission of the λ/2-thick layer of a-SiNz:H. A linewidth of Δλ = 11 nm and a quality factor of Q = 69 are achieved in our one-dimensional a-SiNz photonic crystal microcavities. Measurements of transmittance spectra of the as-grown samples show that the transmittance resonant peak of a cavity mode at 710 nm is introduced into the band gap of one-dimensional photonic crystal distributed Bragg reflector (DBR), which further verifies the microcavity effects.

  14. Demonstration of a stable ultrafast laser based on a nonlinear microcavity

    PubMed Central

    Peccianti, M.; Pasquazi, A.; Park, Y.; Little, B.E.; Chu, S.T.; Moss, D.J.; Morandotti, R.

    2012-01-01

    Ultrashort pulsed lasers, operating through the phenomenon of mode-locking, have had a significant role in many facets of our society for 50 years, for example, in the way we exchange information, measure and diagnose diseases, process materials, and in many other applications. Recently, high-quality resonators have been exploited to demonstrate optical combs. The ability to phase-lock their modes would allow mode-locked lasers to benefit from their high optical spectral quality, helping to realize novel sources such as precision optical clocks for applications in metrology, telecommunication, microchip-computing, and many other areas. Here we demonstrate the first mode-locked laser based on a microcavity resonator. It operates via a new mode-locking method, which we term filter-driven four-wave mixing, and is based on a CMOS-compatible high quality factor microring resonator. It achieves stable self-starting oscillation with negligible amplitude noise at ultrahigh repetition rates, and spectral linewidths well below 130 kHz. PMID:22473009

  15. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  16. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  17. Vertical Microcavity Organic Light-emitting Field-effect Transistors

    PubMed Central

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-01-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm−2, and the corresponding ON/OFF ratio and current efficiency reaches above 104 and 3.1 cdA−1, respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers. PMID:26986944

  18. Vertical Microcavity Organic Light-emitting Field-effect Transistors.

    PubMed

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-01-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm(-2), and the corresponding ON/OFF ratio and current efficiency reaches above 10(4) and 3.1 cdA(-1), respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers. PMID:26986944

  19. Vertical Microcavity Organic Light-emitting Field-effect Transistors

    NASA Astrophysics Data System (ADS)

    Hu, Yongsheng; Lin, Jie; Song, Li; Lu, Qipeng; Zhu, Wanbin; Liu, Xingyuan

    2016-03-01

    Organic light-emitting field-effect transistors (OLEFETs) are regarded as a novel kind of device architecture for fulfilling electrical-pumped organic lasers. However, the realization of OLEFETs with high external quantum efficiency (EQE) and high brightness simultaneously is still a tough task. Moreover, the design of the resonator structure in LED is far from satisfactory. Here, OLEFETs with EQE of 1.5% at the brightness of 2600 cdm‑2, and the corresponding ON/OFF ratio and current efficiency reaches above 104 and 3.1 cdA‑1, respectively, were achieved by introducing 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN) as a charge generation layer. Moreover, a vertical microcavity based on distributed Bragg reflector (DBR) and Ag source/drain electrodes is successfully introduced into the high performance OLEFETs, which results in electroluminescent spectrum linewidth narrowing from 96 nm to 6.9 nm. The results manifest the superiority of the vertical microcavity as an optical resonator in OLEFETs, which sheds some light on achieving the electrically pumped organic lasers.

  20. Formation of a suspended lipid membrane on a microcavity covered by a thin SiO2 layer with a nanohole array

    NASA Astrophysics Data System (ADS)

    Tanaka, Aya; Kashimura, Yoshiaki; Kuramochi, Eiichi; Sumitomo, Koji

    2014-01-01

    To provide a platform for a nanobiodevice, we fabricated microcavities on a Si/SiO2 substrate covered by a thin SiO2 layer with nanohole arrays that we call a pepper shaker substrate. Fluorescence and atomic force microscopy images showed that the structure of the pepper shaker substrate improved both the probability of membrane sealing over the microcavities by rupturing giant unilameller vesicles and the lifetime of the lipid membrane suspended over the microcavities. The success of this study reveals the potential for fabricating an artificial cell array as a tool for the functional and high throughput analysis of membrane proteins.

  1. Finite element method analysis of surface acoustic wave devices with microcavities for detection of liquids

    NASA Astrophysics Data System (ADS)

    Senveli, Sukru U.; Tigli, Onur

    2013-12-01

    This paper introduces the use of finite element method analysis tools to investigate the use of a Rayleigh type surface acoustic wave (SAW) sensor to interrogate minute amounts of liquids trapped in microcavities placed on the delay line. Launched surface waves in the ST-X quartz substrate couple to the liquid and emit compressional waves. These waves form a resonant cavity condition and interfere with the surface waves in the substrate. Simulations show that the platform operates in a different mechanism than the conventional mass loading of SAW devices. Based on the proposed detection mechanism, it is able to distinguish between variations of 40% and 90% glycerin based on phase relations while using liquid volumes smaller than 10 pl. Results from shallow microcavities show high correlation with sound velocity parameter of the liquid whereas deeper microcavities display high sensitivities with respect to glycerin concentration. Simulated devices yield a maximum sensitivity of -0.77°/(% glycerin) for 16 μm wavelength operation with 8 μm deep, 24 μm wide, and 24 μm long microcavities.

  2. Planar microcavity-integrated hot-electron photodetector.

    PubMed

    Zhang, Cheng; Wu, Kai; Zhan, Yaohui; Giannini, Vincenzo; Li, Xiaofeng

    2016-05-21

    Hot-electron photodetectors are attracting increasing interest due to their capability in below-bandgap photodetection without employing classic semiconductor junctions. Despite the high absorption in metallic nanostructures via plasmonic resonance, the fabrication of such devices is challenging and costly due to the use of high-dimensional sub-wavelength nanostructures. In this study, we propose a planar microcavity-integrated hot-electron photodetector (MC-HE PD), in which the TCO/semiconductor/metal (TCO: transparent conductive oxide) structure is sandwiched between two asymmetrically distributed Bragg reflectors (DBRs) and a lossless buffer layer. Finite-element simulations demonstrate that the resonant wavelength and the absorption efficiency of the device can be manipulated conveniently by tailoring the buffer layer thickness and the number of top DBR pairs. By benefitting from the largely increased electric field at the resonance frequency, the absorption in the metal can reach 92%, which is a 21-fold enhancement compared to the reference without a microcavity. Analytical probability-based electrical calculations further show that the unbiased responsivity can be up to 239 nA mW(-1), which is more than an order of magnitude larger than that of the reference. Furthermore, the MC-HE PD not only exhibits a superior photoelectron conversion ability compared to the approach with corrugated metal, but also achieves the ability to tune the near infrared multiband by employing a thicker buffer layer. PMID:27128730

  3. Planar microcavity-integrated hot-electron photodetector

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Wu, Kai; Zhan, Yaohui; Giannini, Vincenzo; Li, Xiaofeng

    2016-05-01

    Hot-electron photodetectors are attracting increasing interest due to their capability in below-bandgap photodetection without employing classic semiconductor junctions. Despite the high absorption in metallic nanostructures via plasmonic resonance, the fabrication of such devices is challenging and costly due to the use of high-dimensional sub-wavelength nanostructures. In this study, we propose a planar microcavity-integrated hot-electron photodetector (MC-HE PD), in which the TCO/semiconductor/metal (TCO: transparent conductive oxide) structure is sandwiched between two asymmetrically distributed Bragg reflectors (DBRs) and a lossless buffer layer. Finite-element simulations demonstrate that the resonant wavelength and the absorption efficiency of the device can be manipulated conveniently by tailoring the buffer layer thickness and the number of top DBR pairs. By benefitting from the largely increased electric field at the resonance frequency, the absorption in the metal can reach 92%, which is a 21-fold enhancement compared to the reference without a microcavity. Analytical probability-based electrical calculations further show that the unbiased responsivity can be up to 239 nA mW-1, which is more than an order of magnitude larger than that of the reference. Furthermore, the MC-HE PD not only exhibits a superior photoelectron conversion ability compared to the approach with corrugated metal, but also achieves the ability to tune the near infrared multiband by employing a thicker buffer layer.

  4. Drag effects in a system of electrons and microcavity polaritons

    SciTech Connect

    Berman, Oleg L.; Kezerashvili, Roman Ya.; Lozovik, Yurii E.

    2010-09-15

    The theory of the drag effects in the system of spatially separated electrons and excitons in coupled quantum wells (QWs) embedded in an optical microcavity is developed. It is shown that at low temperature an electron current induces the polariton flow, therefore, a transport of photons along the cavity. However, the electron current dragged by the polariton flow is strongly suppressed below polariton superfluid transition temperature and hence, the strong suppression of the induced electron current indicates the superfluidity of polaritons. Therefore, the transport properties of polaritons can be investigated by measuring the current or voltage in the electron subsystem. At high temperatures, we study the exciton-electron drag effects. At high-temperatures regime, from one hand, the existence of the electric current in an electron QW induces the exciton flow in the other QW, from the other hand, the electron current in one QW induces the exciton flow in the other QW via the drag of excitons by the electrons. The drag coefficients for the polariton-electron systems are calculated and analyzed. We discuss the possible experimental observation of the drag effects in the system of electrons and microcavity polaritons, that also allow to observe the cavity polaritons superfluidity.

  5. Solution processing of microcavity for BioMEMS application

    NASA Astrophysics Data System (ADS)

    Luong, Vu Nam; Ukita, Yoshiaki; Takamura, Yuzuru; Mitani, Tadaoki; Shimoda, Tatsuya; Dung Dang, Thi My; Chien Dang, Mau

    2014-09-01

    Compared to the conventional silicon-based technology, the solution process appears to be a revolution in the field of micro/nanofabrication due to its advantages of high efficiency in material and energy consumption and the use of low cost material. In this paper, we introduce a new approach to fabricate BioMEMS devices using this novel technology to make microcavity. Zirconium oxide patterns were formed on the silicon substrate simply by spin coating its precursor and thermal imprinting technique. We used poly-propylene carbonate (PPC) for the sacrificial material due to its unique pyrolysis property. The PPC was coated on the ZrO patterns and excess film was etched by oxygen plasma but retaining PPC structure between the lines of ZrO pattern. Then another ZrO layer was coated to encapsulate the PPC. The final microcavity structures were obtained by just baking the substrate by pyrolyzing the PPC. The obtained results show the approach’s prospect of becoming an ideal alternative for the current BioMEMS micro/nanofabrication technologies

  6. Millisecond Photon Lifetime in a Slow-Light Microcavity

    NASA Astrophysics Data System (ADS)

    Huet, V.; Rasoloniaina, A.; Guillemé, P.; Rochard, P.; Féron, P.; Mortier, M.; Levenson, A.; Bencheikh, K.; Yacomotti, A.; Dumeige, Y.

    2016-04-01

    Optical microcavities with ultralong photon storage times are of central importance for integrated nanophotonics. To date, record quality (Q ) factors up to 1011 have been measured in millimetric-size single-crystal whispering-gallery-mode (WGM) resonators, and 1010 in silica or glass microresonators. We show that, by introducing slow-light effects in an active WGM microresonator, it is possible to enhance the photon lifetime by several orders of magnitude, thus circumventing both fabrication imperfections and residual absorption. The slow-light effect is obtained from coherent population oscillations in an erbium-doped fluoride glass microsphere, producing strong dispersion of the WGM (group index ng˜106). As a result, a photon lifetime up to 2.5 ms at room temperature has been measured, corresponding to a Q factor of 3 ×1012 at 1530 nm. This system could yield a new type of optical memory microarray with ultralong storage times.

  7. Antenna-coupled microcavities for terahertz emission

    SciTech Connect

    Madéo, J. Todorov, Y.; Sirtori, C.

    2014-01-20

    We have investigated the capacitive coupling between dipolar antennas and metal-dielectric-metal wire microcavities with strong sub-wavelength confinement in the terahertz region. The coupling appears in reflectivity measurements performed on arrays of antenna-coupled elements, which display asymmetric Fano lineshapes. The experimental data are compared to a temporal coupled-mode theory and finite elements electromagnetic simulations. We show that the Fano interferences correspond to coupling between a subradiant mode (microcavity) and a superradiant mode (antennas). This phenomenon allows one to enhance and control the radiative coupling of the strongly confined mode with the vacuum. These concepts are very useful for terahertz optoelectronic devices based on deep-sub-wavelength active regions.

  8. Strain monitoring of bismaleimide composites using embedded microcavity sensor

    NASA Astrophysics Data System (ADS)

    Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

    2016-03-01

    A type of extrinsic Fabry-Perot interferometer (EFPI) fiber optic sensor, i.e., the microcavity strain sensor, is demonstrated for embedded, high-temperature applications. The sensor is fabricated using a femtosecond (fs) laser. The fs-laser-based fabrication makes the sensor thermally stable to sustain operating temperatures as high as 800°C. The sensor has low sensitivity toward the temperature as compared to its response toward the applied strain. The performance of the EFPI sensor is tested in an embedded application. The host material is carbon fiber/bismaleimide (BMI) composite laminate that offer thermally stable characteristics at high ambient temperatures. The sensor exhibits highly linear response toward the temperature and strain. Analytical work done with embedded optical-fiber sensors using the out-of-autoclave BMI laminate was limited until now. The work presented in this paper offers an insight into the strain and temperature interactions of the embedded sensors with the BMI composites.

  9. Facile synthesis of optical microcavities by a rationally designed anodization approach: tailoring photonic signals by nanopore structure.

    PubMed

    Wang, Ye; Chen, Yuting; Kumeria, Tushar; Ding, Fuyuan; Evdokiou, Andreas; Losic, Dusan; Santos, Abel

    2015-05-13

    Structural engineering of porous anodic aluminum oxide (AAO) nanostructures by anodization has been extensively studied in the past two decades. However, the transition of this technique into the fabrication of AAO-based one-dimensional photonic crystal is still challenging. Herein, we report for the first time on the fabrication of AAO optical microcavities by a rationally designed anodization approach. In our study, two feasible methods are used to fabricate microcavities with tunable resonance peak across the visible and near-infrared spectra. Distributed Bragg reflector (DBR) nanostructures are first fabricated by pulse anodization approach, in which the anodization voltage was periodically manipulated to achieve pseudosinusoidal modulation of the effective refractive index gradient along the depth of the AAO nanostructures. Microcavities were created by creating a nanoporous layer of constant porosity between two AAO-DBR nanostructures, and by introducing a shift of the phase of the porosity gradient along the depth of AAO. The position of the resonance peak in these microcavities can be linearly tuned by means of the duration of the high voltage anodization. These optical nanostructures are sensitive to alterations of the effective media inside the nanopores. The AAO microcavity shows a central wavelength shift of 2.58 ± 0.37 nm when exposed to water vapor. Our research highlights the feasibility of anodization technique to fabricate AAO-based photonic nanostructures for advanced sensing applications. PMID:25901537

  10. Transient dual-energy lasing in a semiconductor microcavity

    PubMed Central

    Hsu, Feng-Kuo; Xie, Wei; Lee, Yi-Shan; Lin, Sheng-Di; Lai, Chih Wei

    2015-01-01

    We demonstrate sequential lasing at two well-separated energies in a highly photoexcited planar microcavity at room temperature. Two spatially overlapped lasing states with distinct polarization properties appear at energies more than 5 meV apart. Under a circularly polarized nonresonant 2 ps pulse excitation, a sub-10-ps transient circularly polarized high-energy (HE) state emerges within 10 ps after the pulse excitation. This HE state is followed by a pulsed state that lasts for 20–50 ps at a low energy (LE) state. The HE state is highly circularly polarized as a result of a spin-preserving stimulated process, while the LE state shows a significantly reduced circular polarization because of a diminishing spin imbalance. PMID:26477277

  11. A porous silicon optical microcavity for sensitive bacteria detection

    NASA Astrophysics Data System (ADS)

    Li, Sha; Huang, Jianfeng; Cai, Lintao

    2011-10-01

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (~10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml - 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  12. Integrated vertical microcavity using a nano-scale deformation for strong lateral confinement

    SciTech Connect

    Mai, Lijian Ding, Fei Stöferle, Thilo Knoll, Armin Jan Offrein, Bert Mahrt, Rainer F.

    2013-12-09

    We report on the realization of a solid state Fabry-Pérot-like microcavity that uses a small Gaussian-shaped deformation inside the cavity to achieve strong lateral photon confinement on the order of the wavelength. Cavities with a mode volume V < 0.4 μm{sup 3} and a quality factor Q > 1000 are fabricated by means of focused ion beam milling, removing the necessity for etched sidewalls as required for micropillar cavities. Perylene-diimide dye doped polystyrene was embedded in the microcavity and probed by time-resolved microphotoluminescence. A Purcell enhancement of the spontaneous emission rate by a factor of 3.5 has been observed at room temperature.

  13. High-quality-factor planar optical cavities with laterally stopped, slowed, or reversed light.

    PubMed

    Byrnes, Steven J; Khorasaninejad, Mohammadreza; Capasso, Federico

    2016-08-01

    In a planar optical cavity, the resonance frequencies increase as a function of in-plane wavevector according to a standard textbook formula. This has well-known consequences in many different areas of optics, from the shifts of etalon peaks at non-normal angles, to the properties of transverse modes in laser diodes, to the effective mass of microcavity photons, and so on. However, this standard formula is valid only when the reflection phase of each cavity mirror is approximately independent of angle. There is a certain type of mirror-a subwavelength dielectric grating near a guided mode resonance-with not only a strongly angle-dependent reflection phase, but also very high reflectance and low losses. Simulations show that by using such mirrors, high-quality-factor planar cavities can be designed that break all these textbook rules, leading to resonant modes that are slow, stopped or even backward-propagating in the in-plane direction. In particular, we demonstrate experimentally high-Q planar cavities whose resonance frequency is independent of in-plane wavevector-i.e., the resonant modes have zero in-plane group velocity, for one polarization but both in-plane directions. We discuss potential applications in various fields including lasers, quantum optics, and exciton-polariton condensation. PMID:27505803

  14. Tuneable polaritonics at room temperature with strongly coupled Tamm plasmon polaritons in metal/air-gap microcavities

    NASA Astrophysics Data System (ADS)

    Grossmann, C.; Coulson, C.; Christmann, G.; Farrer, I.; Beere, H. E.; Ritchie, D. A.; Baumberg, J. J.

    2011-06-01

    We report strong coupling between Tamm plasmons and excitons in III-V quantum wells at room temperature in ultracompact sample designs. A high refractive index contrast air-gap mirror together with optical Tamm states at a metal/semiconductor interface tightly confines the intracavity field leading to substantial local field enhancements. Angular-resolved reflectivity spectra give clear evidence for anticrossing in the dispersion relation. Room temperature Rabi splittings of 10 meV are found in excellent agreement with simulations. Electrical control of the polariton modes is realized without need for doped mirror layers. Such air-gap microcavities open innovative possibilites for electrically tunable microcavities and polaritonic microelectromechanics.

  15. Spin–orbit coupling of light in asymmetric microcavities

    PubMed Central

    Ma, L. B.; Li, S. L.; Fomin, V. M.; Hentschel, M.; Götte, J. B.; Yin, Y.; Jorgensen, M. R.; Schmidt, O. G.

    2016-01-01

    When spinning particles, such as electrons and photons, undergo spin–orbit coupling, they can acquire an extra phase in addition to the well-known dynamical phase. This extra phase is called the geometric phase (also known as the Berry phase), which plays an important role in a startling variety of physical contexts such as in photonics, condensed matter, high-energy and space physics. The geometric phase was originally discussed for a cyclically evolving physical system with an Abelian evolution, and was later generalized to non-cyclic and non-Abelian cases, which are the most interesting fundamental subjects in this area and indicate promising applications in various fields. Here, we enable optical spin–orbit coupling in asymmetric microcavities and experimentally observe a non-cyclic optical geometric phase acquired in a non-Abelian evolution. Our work is relevant to fundamental studies and implies promising applications by manipulating photons in on-chip quantum devices. PMID:26987401

  16. Spin-orbit coupling of light in asymmetric microcavities.

    PubMed

    Ma, L B; Li, S L; Fomin, V M; Hentschel, M; Götte, J B; Yin, Y; Jorgensen, M R; Schmidt, O G

    2016-01-01

    When spinning particles, such as electrons and photons, undergo spin-orbit coupling, they can acquire an extra phase in addition to the well-known dynamical phase. This extra phase is called the geometric phase (also known as the Berry phase), which plays an important role in a startling variety of physical contexts such as in photonics, condensed matter, high-energy and space physics. The geometric phase was originally discussed for a cyclically evolving physical system with an Abelian evolution, and was later generalized to non-cyclic and non-Abelian cases, which are the most interesting fundamental subjects in this area and indicate promising applications in various fields. Here, we enable optical spin-orbit coupling in asymmetric microcavities and experimentally observe a non-cyclic optical geometric phase acquired in a non-Abelian evolution. Our work is relevant to fundamental studies and implies promising applications by manipulating photons in on-chip quantum devices. PMID:26987401

  17. Tunable polaritonic molecules in an open microcavity system

    SciTech Connect

    Dufferwiel, S.; Li, Feng Giriunas, L.; Walker, P. M.; Skolnick, M. S.; Krizhanovskii, D. N.; Trichet, A. A. P.; Smith, J. M.; Farrer, I.; Ritchie, D. A.

    2015-11-16

    We experimentally demonstrate tunable coupled cavities based upon open access zero-dimensional hemispherical microcavities. The modes of the photonic molecules are strongly coupled with quantum well excitons forming a system of tunable polaritonic molecules. The cavity-cavity coupling strength, which is determined by the degree of modal overlap, is controlled through the fabricated centre-to-centre distance and tuned in-situ through manipulation of both the exciton-photon and cavity-cavity detunings by using nanopositioners to vary the mirror separation and angle between them. We demonstrate micron sized confinement combined with high photonic Q-factors of 31 000 and lower polariton linewidths of 150 μeV at resonance along with cavity-cavity coupling strengths between 2.5 meV and 60 μeV for the ground cavity state.

  18. Fresnel filtering of Gaussian beams in microcavities.

    PubMed

    Shinohara, Susumu; Harayama, Takahisa; Fukushima, Takehiro

    2011-03-15

    We study the output from the modes described by the superposition of Gaussian beams confined in the quasi-stadium microcavities. We experimentally observe the deviation from Snell's law in the output when the incident angle of the Gaussian beam at the cavity interface is near the critical angle for total internal reflection, providing direct experimental evidence on the Fresnel filtering. The theory of the Fresnel filtering for a planar interface qualitatively reproduces experimental data, and a discussion is given on small deviation between the measured data and the theory. PMID:21403763

  19. Cascaded integrated waveguide linear microcavity filters

    NASA Astrophysics Data System (ADS)

    Pruessner, Marcel W.; Stievater, Todd H.; Goetz, Peter G.; Rabinovich, William S.; Urick, Vincent J.

    2013-07-01

    We experimentally demonstrate cascaded Fabry-Perot microcavity filters fabricated on silicon-on-insulator substrates. The cavities are formed by etching three sets of quarter-wavelength trenches along a rib waveguide, each set forming a Bragg reflector. Various configurations are examined with a view towards maximizing the filter extinction and minimizing the linewidth. We investigate the origin of spurious cavity modes and show how these are minimized. The effect of mode-splitting due to inter-cavity coupling is suppressed by increasing the reflectivity of the center mirror. Experimental results compare well with transfer matrix predictions.

  20. Angular Dependence of the Sharply Directed Emission in Organic Light Emitting Diodes with a Microcavity Structure

    NASA Astrophysics Data System (ADS)

    Juang, Fuh-Shyang; Laih, Li-Hong; Lin, Chia-Ju; Hsu, Yu-Jen

    2002-04-01

    An optical microcavity structure was used in organic light emitting diodes. We succeeded in fabricating a device with sharply directed emission vertical to an emission surface. The device shows green emission (bright green) at normal position which turns red (bright red) at the 30° position. The angular dependences of the electroluminescence and the emission patterns versus viewing angle in the microcavity OLED were studied. The resonance wavelength λ decreases with viewing angle. The emission peak at 490 nm is directed vertically to the device surface more sharply than that at 632 nm. The microcavity structure shows non-Lambertian emission. The spectra appear more blue off-axis and the intensity of the green-like emission decreases rapidly with increasing viewing angle. A significantly narrow linewidth of 7.4 nm in the 0° direction for the 490 nm peak was observed. The full-widths at half maximum (FWHM) of the green-like spectra are much smaller than those of the red-like ones, indicating better cavity quality.

  1. Scalable photonic quantum computing assisted by quantum-dot spin in double-sided optical microcavity.

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2013-07-29

    We investigate the possibility of achieving scalable photonic quantum computing by the giant optical circular birefringence induced by a quantum-dot spin in a double-sided optical microcavity as a result of cavity quantum electrodynamics. We construct a deterministic controlled-not gate on two photonic qubits by two single-photon input-output processes and the readout on an electron-medium spin confined in an optical resonant microcavity. This idea could be applied to multi-qubit gates on photonic qubits and we give the quantum circuit for a three-photon Toffoli gate. High fidelities and high efficiencies could be achieved when the side leakage to the cavity loss rate is low. It is worth pointing out that our devices work in both the strong and the weak coupling regimes. PMID:23938640

  2. Intensity modulated SMF cascaded tapers with a hollow core PCF based microcavity for curvature sensing

    NASA Astrophysics Data System (ADS)

    Dass, Sumit; Narayan Dash, Jitendra; Jha, Rajan

    2016-03-01

    We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m-1 is observed in the curvature range 0 to 1 m-1 for a second taper diameter of 18 μm. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.

  3. Excellence through High-Quality Individualization.

    ERIC Educational Resources Information Center

    Burns, Richard W.; Klingstedt, Joe Lars

    1988-01-01

    Proposes a strategy employing challenge, functionalism, high-order learning, and originality to achieve high-quality individualization in course work. Asserts that individualized instruction better prepares students to solve problems, make decisions, and produce original ideas. (MM)

  4. Resonant microcavity light emitters for onboard exhaust emissions IR sensor

    NASA Astrophysics Data System (ADS)

    Levy, Francois; Picard, Emmanuel; Rothmann, Johan; Mottin, Eric; Hadji, Emmanuel; Duhr, Joel

    2005-02-01

    A sensor based on selective optical absorption allows monitoring of hazardous engine exhaust emissions such as gaseous hydrocarbons and carbon monoxide. The IR components presented here offer the potential to develop a compact, fast and selective sensor reaching the technical and cost requirements for on-board automotive applications. Optical gas monitoring requires light sources above 3&mum since most of the gas species have their fundamental absorption peaks between 3 and 6 &mum. We report here on resonant microcavity light sources emitting at room temperature between 3 and 5&mum. The emitter combines a CdxHg1-xTe light emitting heterostructure and two dielectric multilayered mirrors. It is optically pumped by a commercial III-V laser diode. The principle of the resonant microcavity emitter allows tailoring of the emission wavelength and the line width to fit the absorption band of a specific gas, ensuring a very good selectivity between species. Moreover, this kind of emitter allows fast modulation enabling high detectivity and short response time. We report performances of light sources in the range 3-5&mum allowing the detection of hydrocarbons and carbon monoxide. Association of emitters peaking at different characteristic wavelengths with a single broad band detector allows designing of an optical sensor for several gas species. Sensitivity and time response issues have been characterized: detection of less than 50ppm of CH4 on a 15cm path has been demonstrated on synthetic gas; analysis of exhaust gases from a vehicle has allowed cylinder to cylinder resolution. This optical sensor offers the potential of various on-board automotive applications.

  5. Electrically-detected magnetic resonance in semiconductor nanostructures inserted in microcavities

    NASA Astrophysics Data System (ADS)

    Bagraev, Nikolay; Danilovskii, Eduard; Gehlhoff, Wolfgang; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna; Mashkov, Vladimir; Romanov, Vladimir

    2013-12-01

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance caused by the microcavities embedded in the Si-QW plane.

  6. 3D PIC Modeling of Microcavity Discharge

    NASA Astrophysics Data System (ADS)

    Hopkins, Matthew; Manginell, Ronald; Moore, Christopher; Yee, Benjamin; Moorman, Matthew

    2015-09-01

    We present a number of techniques and challenges in simulating the transient behavior of a microcavity discharge. Our microcavities are typically cylindrical with diameters approximately 50 - 100 μm, heights of 50 - 200 μm, pressure near atmospheric, and operate at a few hundred volts. We employ a fully kinetic simulation methodology, the Particle-in-Cell (PIC) method, with interparticle collisions handled via methods based on direct simulation Monte Carlo (DSMC). In particular, we explicitly include kinetic electrons. Some of the challenges we encounter include variations in number densities, external circuit coupling, and time step resolution constraints. By employing dynamic particle weighting (particle weights vary over time by species and location) we can mitigate some of the challenges modeling systems with 107 variations in number densities. Smoothing mechanisms have been used to attempt to mitigate external circuit response. We perform our simulations on hundreds or thousands of processing cores to accommodate the computational work inherent in using relatively small time step sizes (e.g., 50 fs for a 100 ns calculation). In addition, particle weighting issues inherent to three-dimensional low temperature plasma systems will be mentioned. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE-AC04-94AL85000.

  7. Weak-microcavity organic light-emitting diodes with improved light out-coupling.

    PubMed

    Cho, Sang-Hwan; Song, Young-Woo; Lee, Joon-gu; Kim, Yoon-Chang; Lee, Jong Hyuk; Ha, Jaeheung; Oh, Jong-Suk; Lee, So Young; Lee, Sun Young; Hwang, Kyu Hwan; Zang, Dong-Sik; Lee, Yong-Hee

    2008-08-18

    We propose and demonstrate weak-microcavity organic light-emitting diode (OLED) displays with improved light-extraction and viewing-angle characteristics. A single pair of low- and high-index layers is inserted between indium tin oxide (ITO) and a glass substrate. The electroluminescent (EL) efficiencies of discrete red, green, and blue weak-microcavity OLEDs are enhanced by 56%, 107%, and 26%, respectively, with improved color purity. Moreover, full-color passive-matrix bottom-emitting OLED displays are fabricated by employing low-index layers of two thicknesses. As a display, the EL efficiency of white color was 27% higher than that of a conventional OLED display. PMID:18711500

  8. One- and two-photon photocurrents from tunable organic microcavity photodiodes

    NASA Astrophysics Data System (ADS)

    Koeppe, R.; Müller, J. G.; Lupton, J. M.; Feldmann, J.; Scherf, U.; Lemmer, U.

    2003-04-01

    We have constructed multilayer thin-film organic microcavity photodiodes with the photoactive layer comprised of a spin-coated conjugated polymer and an evaporated C60 layer. The electrodes are designed as semitransparent mirrors which form a resonant cavity structure. The photocurrent spectra show distinct maxima at the optical resonances of the cavities, which are located up to 200 nm below the fundamental optical transition of the polymer. The design allows a simple tuning of the spectral response by varying the layer thickness. Microcavity photodiodes are also shown to be highly sensitive two-photon detectors, which exhibit a factor 500 improvement in the two-photon response compared to devices without photonic confinement.

  9. Tuning the Microcavity of Organic Light Emitting Diodes by Solution Processable Polymer-Nanoparticle Composite Layers.

    PubMed

    Preinfalk, Jan B; Schackmar, Fabian R; Lampe, Thomas; Egel, Amos; Schmidt, Tobias D; Brütting, Wolfgang; Gomard, Guillaume; Lemmer, Uli

    2016-02-01

    In this study, we present a simple method to tune and take advantage of microcavity effects for an increased fraction of outcoupled light in solution-processed organic light emitting diodes. This is achieved by incorporating nonscattering polymer-nanoparticle composite layers. These tunable layers allow the optimization of the device architecture even for high film thicknesses on a single substrate by gradually altering the film thickness using a horizontal dipping technique. Moreover, it is shown that the optoelectronic device parameters are in good agreement with transfer matrix simulations of the corresponding layer stack, which offers the possibility to numerically design devices based on such composite layers. Lastly, it could be shown that the introduction of nanoparticles leads to an improved charge injection, which combined with an optimized microcavity resulted in a maximum luminous efficacy increase of 85% compared to a nanoparticle-free reference device. PMID:26744904

  10. Efficient single-photon emitters based on Bragg microcavities containing selectively positioned InAs quantum dots

    SciTech Connect

    Gaisler, V. A. Gaisler, A. V.; Jaroshevich, A. S.; Derebezov, I. A.; Kachanova, M. M.; Zhivodkov, Yu. A.; Gavrilova, T. A.; Medvedev, A. S.; Nenasheva, L. A.; Grachev, K. V.; Sandyrev, V. K.; Kozhuhov, A. S.; Shayahmetov, V. M.; Kalagin, A. K.; Bakarov, A. K.; Dmitriev, D. V.; Toropov, A. I.; Shcheglov, D. V.; Latyshev, A. V.; Aseev, A. L.

    2015-01-15

    A semiconductor Bragg microcavity structure for single photon emitters is designed and implemented. The design provides the efficient current pumping of selectively positioned InAs quantum dots within a micrometer-size aperture, high external quantum yield, and low divergence of the emitted radiation.

  11. Surface-plasmon-enhanced microcavity organic light-emitting diodes.

    PubMed

    Zhang, Hongmei; Chen, Shufen; Zhao, Dewei

    2014-12-15

    Efficiency enhancement of organic light-emitting diodes (OLEDs) can be obtained by the combination of microcavity effect and Au nanoparticles based surface plasmons. Au nanoparticles are thermally deposited on distributed Bragg reflector (DBR)-coated glass substrate, leading to realization of microcavity effect and localized surface plasmon effect. Our results show the current efficiency of OLEDs with DBR/Au nanoparticles as anode is increased by 72% compared to that with ITO as anode. PMID:25607492

  12. Pool boiling on surfaces with mini-fins and micro-cavities

    NASA Astrophysics Data System (ADS)

    Pastuszko, Robert; Piasecka, Magdalena

    2012-11-01

    The experimental studies presented here focused on pool boiling heat transfer on mini-fin arrays, mini-fins with perforated covering and surfaces with micro-cavities. The experiments were carried out for water and fluorinert FC-72 at atmospheric pressure. Mini-fins of 0.5 and 1 mm in height were uniformly spaced on the base surface. The copper foil with holes of 0.1 mm in diameter (pitch 0.2/0.4 mm), sintered with the fin tips, formed a system of connected perpendicular and horizontal tunnels. The micro-cavities were obtained through spark erosion. The maximal depth of the craters of these cavities was 15 - 30 μm and depended on the parameters of the branding-pen settings. At medium and small heat fluxes, structures with mini-fins showed the best boiling heat transfer performance both for water and FC-72. At medium and high heat fluxes (above 70 kW/m2 for water and 25 kW/m2 for FC-72), surfaces with mini-fins without porous covering and micro-cavities produced the highest heat transfer coefficients. The surfaces obtained with spark erosion require a proper selection of geometrical parameters for particular liquids - smaller diameters of cavities are suitable for liquids with lower surface tension (FC-72).

  13. Assuring quality in high-consequence engineering

    SciTech Connect

    Hoover, Marcey L.; Kolb, Rachel R.

    2014-03-01

    In high-consequence engineering organizations, such as Sandia, quality assurance may be heavily dependent on staff competency. Competency-dependent quality assurance models are at risk when the environment changes, as it has with increasing attrition rates, budget and schedule cuts, and competing program priorities. Risks in Sandia's competency-dependent culture can be mitigated through changes to hiring, training, and customer engagement approaches to manage people, partners, and products. Sandia's technical quality engineering organization has been able to mitigate corporate-level risks by driving changes that benefit all departments, and in doing so has assured Sandia's commitment to excellence in high-consequence engineering and national service.

  14. Squeezed state generation in photonic crystal microcavities.

    PubMed

    Banaee, M G; Young, Jeff F

    2008-12-01

    The feasibility of using a parametric down-conversion process to generate squeezed electromagnetic states in three dimensional photonic crystal microcavity structures is investigated for the first time. The spectrum of the squeezed light is theoretically calculated by using an open cavity quantum mechanical formalism. The cavity communicates with two main channels, which model vertical radiation losses and coupling into a single-mode waveguide respectively. The amount of squeezing is determined by the correlation functions relating the field quadratures of light coupled into the waveguide. All of the relevant model parameters are realistically estimated for structures made in Al0.3Ga0.7As, using finite-difference time-domain simulations. Squeezing up to approximately 30% below the shot noise level is predicted for 10 mW average power, 80 MHz repetition, 500 ps excitation pulses using in a [111] oriented wafer. PMID:19065230

  15. Are high-quality mates always attractive?

    PubMed Central

    Holveck, Marie-Jeanne; Verhulst, Simon; Fawcett, Tim W

    2010-01-01

    Sexual selection theory posits that females should choose mates in a way that maximizes their reproductive success. But what exactly is the optimal choice? Most empirical research is based on the assumption that females seek a male of the highest possible quality (in terms of the genes or resources he can provide), and hence show directional preferences for indicators of male quality. This implies that attractiveness and quality should be highly correlated. However, females frequently differ in what they find attractive. New theoretical and empirical insights provide mounting evidence that a female’s own quality biases her judgement of male attractiveness, such that male quality and attractiveness do not always coincide. A recent experiment in songbirds demonstrated for the first time that manipulation of female condition can lead to divergent female preferences, with low-quality females actively preferring low-quality males over high-quality males. This result is in line with theory on state-dependent mate choice and is reminiscent of assortative mating preferences in humans. Here we discuss the implications of this work for the study of mate preferences. PMID:20714411

  16. Millisecond Photon Lifetime in a Slow-Light Microcavity.

    PubMed

    Huet, V; Rasoloniaina, A; Guillemé, P; Rochard, P; Féron, P; Mortier, M; Levenson, A; Bencheikh, K; Yacomotti, A; Dumeige, Y

    2016-04-01

    Optical microcavities with ultralong photon storage times are of central importance for integrated nanophotonics. To date, record quality (Q) factors up to 10^{11} have been measured in millimetric-size single-crystal whispering-gallery-mode (WGM) resonators, and 10^{10} in silica or glass microresonators. We show that, by introducing slow-light effects in an active WGM microresonator, it is possible to enhance the photon lifetime by several orders of magnitude, thus circumventing both fabrication imperfections and residual absorption. The slow-light effect is obtained from coherent population oscillations in an erbium-doped fluoride glass microsphere, producing strong dispersion of the WGM (group index n_{g}∼10^{6}). As a result, a photon lifetime up to 2.5 ms at room temperature has been measured, corresponding to a Q factor of 3×10^{12} at 1530 nm. This system could yield a new type of optical memory microarray with ultralong storage times. PMID:27081979

  17. Setting standards for high-quality placements.

    PubMed

    Aitkenhead, Susan; Farran, Sean; Bateman, Ian

    As part of a project undertaken by a local education and training board, a wide range of stakeholders across South London were asked what makes a high-quality practice placement for student nurses, and how that quality could be effectively measured. This article outlines the drafting and testing of a set of quality standards in a mix of provider settings. Although further refinement is required, the standards enabled placement sites to question themselves about their own education and training processes, strengthened their partnership with the training and education board and facilitated the assurance that student nurses receive safe, effective and compassionate preparation when they are on placement. PMID:26434190

  18. Students' Perceptions of High Quality Science Teaching.

    ERIC Educational Resources Information Center

    Palmer, David

    1999-01-01

    Describes a study that sought to identify the attributes of high-quality science teachers at the junior high school level from the point of view of recent ex-students. Students described their best science teachers as presenting interesting and well-integrated hands-on activities, using a range of strategies to make lessons fun and interesting for…

  19. Room-temperature light emission from an airbridge double-heterostructure microcavity of Er-doped Si photonic crystal

    NASA Astrophysics Data System (ADS)

    Wang, Yue; An, Jun-ming; Wu, Yuan-da; Hu, Xiong-wei

    2016-01-01

    We experimentally demonstrate an efficient enhancement of luminescence from two-dimensional (2D) hexagonal photonic crystal (PC) airbridge double-heterostructure microcavity with Er-doped silicon (Si) as light emitters on siliconon-insulator (SOI) wafer at room temperature. A single sharp resonant peak at 1 529.6 nm dominates the photoluminescence (PL) spectrum with the pumping power of 12.5 mW. The obvious red shift and the degraded quality factor (Q-factor) of resonant peak appear with the pumping power increasing, and the maximum measured Q-factor of 4 905 is achieved at the pumping power of 1.5 mW. The resonant peak is observed to shift depending on the structural parameters of PC, which indicates a possible method to control the wavelength of enhanced luminescence for Si-based light emitters based on PC microcavity.

  20. Characteristics of High-Quality Teachers

    ERIC Educational Resources Information Center

    Jones, Jason E.; Gulek, James C.

    2010-01-01

    The purpose of this study was to examine the characteristics of high-quality teachers who used a structured mathematics program for teaching, namely the Math Achievement Program (MAP[superscript 2]D), which demonstrated significant gains on student achievement as measured by California's Standards Test (CST) in mathematics. Specifically, the…

  1. GaN hemispherical micro-cavities

    NASA Astrophysics Data System (ADS)

    Zhang, Yiyun; Feng, Cong; Wang, T.; Choi, H. W.

    2016-01-01

    GaN-based micro-dome optical cavities supported on Si pedestals have been demonstrated by dry etching through gradually shrinking microspheres followed by wet-etch undercutting. Optically pumped whispering-gallery modes (WGMs) have been observed in the near-ultraviolet within the mushroom-like cavities, which do not support Fabry-Pérot resonances. The WGMs blue-shift monotonously as the excitation energies are around the lasing threshold. Concurrently, the mode-hopping effect is observed as the gain spectrum red-shifts under higher excitations. As the excitation energy density exceeds ˜15.1 mJ/cm2, amplified spontaneous emission followed by optical lasing is attained at room temperature, evident from a super-linear increase in emission intensity together with linewidth reduction to ˜0.7 nm for the dominant WGM. Optical behaviors within these WGM microcavities are further investigated using numerical computations and three-dimensional finite-difference time-domain simulations.

  2. Spontaneous emission and oscillation in a planar microcavity dye laser

    NASA Astrophysics Data System (ADS)

    Osuge, Michihiro; Ujihara, Kikuo

    1994-09-01

    Characteristics of a planar microcavity laser using rhodamine 6G with pulsed excitation is studied. Theoretical aspects of controlled spontaneous emission and oscillation in a planar microcavity laser are discussed. The measured spectrum and the angular divergence of spontaneous emission below threshold are in good agreement with theory. The angular divergence yields the radius of the cavity quasimode. The spontaneous emission coupling ratio obtained from the measured input-output characteristics is in reasonable agreement with the theoretical value. The expression for the coupling ratio derived for a Fabry-Perot-type microcavity is shown to be essentially equal to that of a closed cavity or guided mode cavity derived by Yamamoto, Machida, and Bjoerk (1991). The observed spectral behavior near the threshold approximately follows the Schawlow-Townes formula, but for a limited range of output power. The observed spectrum and divergence above threshold indicate incoherence much worse than the Schawlow-Townes limit.

  3. Microcavity single virus detection and sizing with molecular sensitivity

    NASA Astrophysics Data System (ADS)

    Dantham, V. R.; Holler, S.; Kolchenko, V.; Wan, Z.; Arnold, S.

    2013-02-01

    We report the label-free detection and sizing of the smallest individual RNA virus, MS2 by a spherical microcavity. Mass of this virus is ~6 ag and produces a theoretical resonance shift ~0.25 fm upon adsorbing an individual virus at the equator of the bare microcavity, which is well below the r.m.s background noise of 2 fm. However, detection was accomplished with ease (S/N = 8, Q = 4x105) using a single dipole stimulated plasmonic-nanoshell as a microcavity wavelength shift enhancer. Analytical expressions based on the "reactive sensing principle" are developed to extract the radius of the virus from the measured signals. Estimated limit of detection for these experiments was ~0.4 ag or 240 kDa below the size of all known viruses, largest globular and elongated proteins [Phosphofructokinase (345 kDa) and Fibrinogen (390 kDa), respectively].

  4. Spin noise amplification and giant noise in optical microcavity

    SciTech Connect

    Ryzhov, I. I.; Poltavtsev, S. V.; Kozlov, G. G.; Zapasskii, V. S.; Kavokin, A. V.; Lagoudakis, P. V.

    2015-06-14

    When studying the spin-noise-induced fluctuations of Kerr rotation in a quantum-well microcavity, we have found a dramatic increase of the noise signal (by more than two orders of magnitude) in the vicinity of anti-crossing of the polariton branches. The effect is explained by nonlinear optical instability of the microcavity giving rise to the light-power-controlled amplification of the polarization noise signal. In the framework of the developed model of built-in amplifier, we also interpret the nontrivial spectral and intensity-related properties of the observed noise signal below the region of anti-crossing of polariton branches. The discovered effect of optically controllable amplification of broadband polarization signals in microcavities in the regime of optical instability may be of interest for detecting weak oscillations of optical anisotropy in fundamental research and for other applications in optical information processing.

  5. First results with a microcavity plasma panel detector

    SciTech Connect

    Ball, Robert; Ben Moshe, M.; Benhammou, Yan; Chapman, J. Wehrley; Etzion, E; Ferretti, Claudio; Friedman, Dr. Peter S.; Levin, Daniel S.; Silver, Yiftah; Varner Jr, Robert L; Weaverdyck, Curtis; Zhou, Bing; Bensimon, R; Davies, Merlin

    2015-01-01

    A new type of gaseous micropattern particle detector based on a closed-cell microcavity plasma panel sensor is reported. The first device was fabricated with 1 x 1 x 2 mm cells. It has shown very clean signals of 0.6-2.5 V amplitude, fast rise time of approximately 2 ns and FWHM of about 2 ns with very uniform signal shapes across all pixels. From initial measurements with beta particles from a radioactive source, a maximum pixel efficiency greater than 95% is calculated, for operation of the detector over a 100 V wide span of high voltages (HV). Over this same HV range, the background rate per pixel was measured to be 3-4 orders of magnitude lower than the rate with which the cell was illuminated by the beta source. Pixel-to-pixel count rate uniformity is within 3% and stable within 3% for many days. The time resolution is 2.4 ns, and a very low cell-to-cell crosstalk has been measured between cells separated by 2 mm. (C) 2014 Elsevier B.V. All rights reserved.

  6. First results with a microcavity plasma panel detector

    NASA Astrophysics Data System (ADS)

    Ball, R.; Ben-Moshe, M.; Benhammou, Y.; Bensimon, R.; Chapman, J. W.; Davies, M.; Etzion, E.; Ferretti, C.; Friedman, P. S.; Levin, D. S.; Silver, Y.; Varner, R. L.; Weaverdyck, C.; Zhou, B.

    2015-06-01

    A new type of gaseous micropattern particle detector based on a closed-cell microcavity plasma panel sensor is reported. The first device was fabricated with 1×1×2 mm cells. It has shown very clean signals of 0.6-2.5 V amplitude, fast rise time of approximately 2 ns and FWHM of about 2 ns with very uniform signal shapes across all pixels. From initial measurements with β particles from a radioactive source, a maximum pixel efficiency greater than 95% is calculated, for operation of the detector over a 100 V wide span of high voltages (HV). Over this same HV range, the background rate per pixel was measured to be 3-4 orders of magnitude lower than the rate with which the cell was illuminated by the β source. Pixel-to-pixel count rate uniformity is within 3% and stable within 3% for many days. The time resolution is 2.4 ns, and a very low cell-to-cell crosstalk has been measured between cells separated by 2 mm.

  7. Investigation on spectral response of micro-cavity structure by symmetrical tapered fiber tips

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

    2016-06-01

    We proposed and experimentally demonstrated a micro-cavity structure made of symmetrical tapered fiber tips. The waist of a conventional fiber taper fabricated from heating and stretching technique is symmetrically cleaved, and the aligned fiber tips with air gap constitute a Fabry-Perot micro-cavity due to the reflection at the tip facet. The spectral responses of such micro-cavity structure have been investigated both in beam propagation models and experiments. The multibeam interference in the micro-cavity and the impact of the waist diameter and cavity length on the spectral response has been successfully demonstrated. And a micro-cavity structure with 45 μm waist diameter was experimentally achieved, the measured spectra agree well with the simulation ones, indicating that the spectral response of the micro-cavity structure is contributed by both the multibeam interference and the Fabry-Perot micro-cavity.

  8. Theory of polariton-mediated Raman scattering in microcavities.

    PubMed

    León Hilario, L M; Bruchhausen, A; Lobos, A M; Aligia, A A

    2007-04-30

    We calculate the intensity of the polariton-mediated inelastic light scattering in semiconductor microcavities. We treat the exciton-photon coupling nonperturbatively and incorporate lifetime effects in both excitons and photons, and a coupling of the photons to the electron-hole continuum. Taking the matrix elements as fitting parameters, the results are in excellent agreement with measured Raman intensities due to optical phonons that are resonant with the upper polariton branches in II-VI microcavities with embedded CdTe quantum wells. PMID:21690956

  9. Antenna-coupled microcavities for enhanced infrared photo-detection

    SciTech Connect

    Nga Chen, Yuk; Todorov, Yanko Askenazi, Benjamin; Vasanelli, Angela; Sirtori, Carlo; Biasiol, Giorgio; Colombelli, Raffaele

    2014-01-20

    We demonstrate mid-infrared detectors embedded into an array of double-metal nano-antennas. The antennas act as microcavities that squeeze the electric field into thin semiconductor layers, thus enhancing the detector responsivity. Furthermore, thanks to the ability of the antennas to gather photons from an area larger than the device's physical dimensions, the dark current is reduced without hindering the photo-generation rate. In these devices, the background-limited performance is improved with a consequent increase of the operating temperature. Our results illustrate how the antenna-coupled microcavity concept can be applied to enhance the performances of infrared opto-electronic devices.

  10. Low dimensional GaAs/air vertical microcavity lasers

    SciTech Connect

    Gessler, J.; Steinl, T.; Fischer, J.; Höfling, S.; Schneider, C.; Kamp, M.; Mika, A.; Sęk, G.; Misiewicz, J.

    2014-02-24

    We report on the fabrication of gallium arsenide (GaAs)/air distributed Bragg reflector microresonators with indium gallium arsenide quantum wells. The structures are studied via momentum resolved photoluminescence spectroscopy which allows us to investigate a pronounced optical mode quantization of the photonic dispersion. We can extract a length parameter from these quantized states whose upper limit can be connected to the lateral physical extension of the microcavity via analytical calculations. Laser emission from our microcavity under optical pumping is observed in power dependent investigations.

  11. Near-Field Enhancement and Absorption Properties of Metal-Dielectric-Metal Microcavities in the Mid-Infrared Range

    NASA Astrophysics Data System (ADS)

    Heng, Hang; Yang, Li; Ye, Yong-Hong

    2014-01-01

    An important property of optical metamaterials is the ability to concentrate light into extremely tiny volumes, so as to enhance their interaction with quantum objects. In this work, we numerically study the near-field enhancement and absorption properties inside the cylindrical microcavities formed by a Au-GaAs-Au sandwiched structure. At normal incidence, the obtained reflection spectra show that the resonance wavelength of microcavities operates in the range of 5-5.8 μm. We also calculate the contrast C (C = 1 - Rmin), which can be increased to 97% by optimizing the structure's geometry parameters. Moreover, we demonstrate that the multilayer structure with sub-wavelength electromagnetic confinement allows 103-104-fold enhancement of the electromagnetic energy density inside the cavities, which contains the most energy of the incident electromagnetic radiation and has a higher quality factor Q, indicating a narrower linewidth for surface enhanced molecular absorption spectroscopy and the tracking of characteristic molecular vibrational modes in the mid-infrared region. The structure is insensitive to the polarization of the incident wave due to the symmetry of the cylindrical microcavities. The unique properties of the metal-dielectric-metal metamaterials will have potential applications in new plasmonic detectors, bio-sensing and solar cells, etc.

  12. Polariton condensation phase diagram in wide-band-gap planar microcavities: GaN versus ZnO

    NASA Astrophysics Data System (ADS)

    Jamadi, O.; Réveret, F.; Mallet, E.; Disseix, P.; Médard, F.; Mihailovic, M.; Solnyshkov, D.; Malpuech, G.; Leymarie, J.; Lafosse, X.; Bouchoule, S.; Li, F.; Leroux, M.; Semond, F.; Zuniga-Perez, J.

    2016-03-01

    The polariton condensation phase diagram is compared in GaN and ZnO microcavities grown on mesa-patterned silicon substrate. Owing to a common platform, these microcavities share similar photonic properties with large quality factors and low photonic disorder, which makes it possible to determine the optimal spot diameter and to realize a thorough phase diagram study. Both systems have been investigated under the same experimental conditions. The experimental results and the subsequent analysis reveal clearly that longitudinal optical phonons have no influence in the thermodynamic region of the condensation phase diagram, while they allow a strong (slight) decrease of the polariton lasing threshold in the trade-off zone (kinetic region). Phase diagrams are compared with numerical simulations using Boltzmann equations, and are in satisfactory agreement. A lower polariton lasing threshold has been measured at low temperature in the ZnO microcavity, as is expected due to a larger Rabi splitting. This study highlights polariton relaxation mechanisms and their importance in polariton lasing.

  13. Multi-state lasing in self-assembled ring-shaped green fluorescent protein microcavities

    NASA Astrophysics Data System (ADS)

    Dietrich, Christof P.; Höfling, Sven; Gather, Malte C.

    2014-12-01

    We demonstrate highly efficient lasing from multiple photonic states in microcavities filled with self-assembled rings of recombinant enhanced green fluorescent protein (eGFP) in its solid state form. The lasing regime is achieved at very low excitation energies of 13 nJ and occurs from cavity modes dispersed in both energy and momentum. We attribute the momentum distribution to very efficient scattering of incident light at the surface of the eGFP rings. The distribution of lasing states in energy is induced by the large spectral width of the gain spectrum of recombinant eGFP (FWHM ≅ 25 nm).

  14. Raman quantum memory based on an ensemble of nitrogen-vacancy centers coupled to a microcavity

    NASA Astrophysics Data System (ADS)

    Heshami, Khabat; Santori, Charles; Khanaliloo, Behzad; Healey, Chris; Acosta, Victor M.; Barclay, Paul E.; Simon, Christoph

    2014-04-01

    We propose a scheme to realize optical quantum memories in an ensemble of nitrogen-vacancy centers in diamond that are coupled to a microcavity. The scheme is based on off-resonant Raman coupling, which allows one to circumvent optical inhomogeneous broadening and store optical photons in the electronic spin coherence. This approach promises a storage time of order 1 s and a time-bandwidth product of order 107. We include all possible optical transitions in a nine-level configuration, numerically evaluate the efficiencies, and discuss the requirements for achieving high efficiency and fidelity.

  15. Weak-microcavity organic light-emitting diodes with improved light-extraction and wide viewing-angle

    NASA Astrophysics Data System (ADS)

    Cho, Sang-Hwan; Lee, Yong-Hee; Song, Young-Woo; Kim, Yoon-Chang; Lee, Joon-Gu; Lee, Jong Hyuk; Hwang, Kyu Hwan; Zang, Dong-Sik

    2009-02-01

    We propose and demonstrate weak-microcavity organic light-emitting diode (OLED) displays that deliver both a high light-extraction efficiency and wide viewing-angle characteristics. A single pair of low- and high-index layers is inserted between indium tin oxide (ITO) and a glass substrate. The electroluminescent (EL) efficiencies of discrete red, green, and blue weak-microcavity OLEDs (WMOLEDs) are enhanced by 56%, 107%, and 26%, respectively with minimal changes viewing angle and EL spectra characteristics. The color purity is also improved for all three colors. Moreover, we fabricated full-color 128×160 passive-matrix bottom-emitting WMOLED displays to prove their manufacturability. This design is realized by simple one-step 20-nm etching of the low-index layer of red/green subpixels. The EL efficiency of white color in the WMOLED display is 27% higher than that of a conventional OLED display.

  16. Q-factor of (In,Ga)N containing III-nitride microcavity grown by multiple deposition techniques

    SciTech Connect

    Gačević, Ž. Calleja, E.; Réveret, F.

    2013-12-21

    A 3λ/2 (In,Ga)N/GaN resonant cavity, designed for ∼415 nm operation, is grown by molecular beam epitaxy and is sandwiched between a 39.5-period (In,Al)N/GaN distributed Bragg reflector (DBR), grown on c-plane GaN-on-sapphire pseudo-substrate by metal-organic vapor phase epitaxy and an 8-period SiO{sub 2}/ZrO{sub 2} DBR, deposited by electron beam evaporation. Optical characterization reveals an improvement in the cavity emission spectral purity of approximately one order of magnitude due to resonance effects. The combination of spectrophotometric and micro-reflectivity measurements confirms the strong quality (Q)-factor dependence on the excitation spot size. We derive simple analytical formulas to estimate leak and residual absorption losses and propose a simple approach to model the Q-factor and to give a quantitative estimation of the weight of cavity disorder. The model is in good agreement with both transfer-matrix simulation and the experimental findings. We point out that the realization of high Q-factor (In,Ga)N containing microcavities on GaN pseudo-substrates is likely to be limited by the cavity disorder.

  17. Plasmon coupled Fabry-Perot lasing enhancement in graphene/ZnO hybrid microcavity.

    PubMed

    Li, Jitao; Jiang, Mingming; Xu, Chunxiang; Wang, Yueyue; Lin, Yi; Lu, Junfeng; Shi, Zengliang

    2015-01-01

    The response of graphene surface plasmon (SP) in the ultraviolet (UV) region and the realization of short-wavelength semiconductor lasers not only are two hot research areas of great academic and practical significance, but also are two important issues lacked of good understanding. In this work, a hybrid Fabry-Perot (F-P) microcavity, comprising of monolayer graphene covered ZnO microbelt, was constructed to investigate the fundamental physics of graphene SP and the functional extension of ZnO UV lasing. Through the coupling between graphene SP modes and conventional optical microcavity modes of ZnO, improved F-P lasing performance was realized, including the lowered lasing threshold, the improved lasing quality and the remarkably enhanced lasing intensity. The underlying mechanism of the improved lasing performance was proposed based on theoretical simulation and experimental characterization. The results are helpful to design new types of optic and photoelectronic devices based on SP coupling in graphene/semiconductor hybrid structures. PMID:25786359

  18. High quality factor indium oxide mechanical microresonators

    SciTech Connect

    Bartolomé, Javier Cremades, Ana; Piqueras, Javier

    2015-11-09

    The mechanical resonance behavior of as-grown In{sub 2}O{sub 3} microrods has been studied in this work by in-situ scanning electron microscopy (SEM) electrically induced mechanical oscillations. Indium oxide microrods grown by a vapor–solid method are naturally clamped to an aluminum oxide ceramic substrate, showing a high quality factor due to reduced energy losses during mechanical vibrations. Quality factors of more than 10{sup 5} and minimum detectable forces of the order of 10{sup −16} N/Hz{sup 1/2} demonstrate their potential as mechanical microresonators for real applications. Measurements at low-vacuum using the SEM environmental operation mode were performed to study the effect of extrinsic damping on the resonators behavior. The damping coefficient has been determined as a function of pressure.

  19. Exciton condensation in microcavities under three-dimensional quantization conditions

    SciTech Connect

    Kochereshko, V. P. Platonov, A. V.; Savvidis, P.; Kavokin, A. V.; Bleuse, J.; Mariette, H.

    2013-11-15

    The dependence of the spectra of the polarized photoluminescence of excitons in microcavities under conditions of three-dimensional quantization on the optical-excitation intensity is investigated. The cascade relaxation of polaritons between quantized states of a polariton Bose condensate is observed.

  20. Enhancement of the blue photoluminescence intensity for the porous silicon with HfO2 filling into microcavities

    PubMed Central

    Jiang, Ran; Du, Xianghao; Sun, Weideng; Han, Zuyin; Wu, Zhengran

    2015-01-01

    With HfO2 filled into the microcavities of the porous single-crystal silicon, the blue photoluminescence was greatly enhanced at room temperature. On one hand, HfO2 contributes to the light emission with the transitions of the defect levels for oxygen vacancy. On the other hand, the special filling-into-microcavities structure of HfO2 leads to the presence of ferroelectricity, which greatly enhances the blue emission from porous silicon. Since both HfO2 and Si are highly compatible with Si-based electronic industry, combined the low-cost and convenient process, the HfO2-filled porous Si shows a promising application prospect. PMID:26503804

  1. Strong coupling and laser action of ladder-type oligo(p-phenylene)s in a microcavity.

    PubMed

    Höfner, Michael; Kobin, Björn; Hecht, Stefan; Henneberger, Fritz

    2014-12-01

    We investigate the coupling of ladder-type quarterphenyl to the photon modes of a dielectric ZrOx /SiOx microcavity at ultraviolet wavelengths. For a relatively long cavity (≈10 μm) with high-reflectivity mirrors (0.998), optically pumped laser action is demonstrated in the weak-coupling regime. We observe single-mode operation with a threshold of 0.4 mJ cm(-2) . Strong coupling is achieved by using a short λ/2 cavity. We find pronounced anti-crossing features of the molecular (0,0) and (0,1) vibronic transitions and the cavity mode in angle-dependent reflectivity measurements providing Rabi splittings of (90±10) meV. All these features occur spectrally resonant to the exciton transition of ZnO demonstrating the potential of ladder-type oligo(p-phenylene)s for the construction of inorganic/organic hybrid microcavities. PMID:25234768

  2. Near-field radiative heat transfer between two parallel SiO{sub 2} plates with and without microcavities

    SciTech Connect

    Ijiro, T.; Yamada, N.

    2015-01-12

    Near-to-far-field radiative heat transfer between two macroscopic SiO{sub 2} plates—with and without microcavities—was observed using a highly precise and accurate optical gap-measurement method. The experiments, conducted near 300 K, measured heat transfer as a function of gap separation from 1.0 μm to 50 μm and also as a function of temperature differences between 4.1 and 19.5 K. The gap-dependent heat flux was in excellent agreement with theoretical predictions. Furthermore, the effects of microcavities on the plate surfaces were clearly observed and significant enhancement of near-field radiative heat transfer was confirmed between gold-coated microcavities with narrow vacuum separation.

  3. Enhancement of the blue photoluminescence intensity for the porous silicon with HfO2 filling into microcavities.

    PubMed

    Jiang, Ran; Du, Xianghao; Sun, Weideng; Han, Zuyin; Wu, Zhengran

    2015-01-01

    With HfO2 filled into the microcavities of the porous single-crystal silicon, the blue photoluminescence was greatly enhanced at room temperature. On one hand, HfO2 contributes to the light emission with the transitions of the defect levels for oxygen vacancy. On the other hand, the special filling-into-microcavities structure of HfO2 leads to the presence of ferroelectricity, which greatly enhances the blue emission from porous silicon. Since both HfO2 and Si are highly compatible with Si-based electronic industry, combined the low-cost and convenient process, the HfO2-filled porous Si shows a promising application prospect. PMID:26503804

  4. Germanium-on-silicon Vernier-effect photonic microcavities for the mid-infrared.

    PubMed

    Troia, Benedetto; Penades, Jordi Soler; Khokhar, Ali Z; Nedeljkovic, Milos; Alonso-Ramos, Carlos; Passaro, Vittorio M N; Mashanovich, Goran Z

    2016-02-01

    We present Vernier-effect photonic microcavities based on a germanium-on-silicon technology platform, operating around the mid-infrared wavelength of 3.8 μm. Cascaded racetrack resonators have been designed to operate in the second regime of the Vernier effect, and typical Vernier comb-like spectra have been successfully demonstrated with insertion losses of ∼5  dB, maximum extinction ratios of ∼23  dB, and loaded quality factors higher than 5000. Furthermore, an add-drop racetrack resonator designed for a Vernier device has been characterized, exhibiting average insertion losses of 1 dB, extinction ratios of up to 18 dB, and a quality factor of ∼1700. PMID:26907436

  5. Computational Modeling of Photonic Crystal Microcavity Single-Photon Emitters

    NASA Astrophysics Data System (ADS)

    Saulnier, Nicole A.

    Conventional cryptography is based on algorithms that are mathematically complex and difficult to solve, such as factoring large numbers. The advent of a quantum computer would render these schemes useless. As scientists work to develop a quantum computer, cryptographers are developing new schemes for unconditionally secure cryptography. Quantum key distribution has emerged as one of the potential replacements of classical cryptography. It relics on the fact that measurement of a quantum bit changes the state of the bit and undetected eavesdropping is impossible. Single polarized photons can be used as the quantum bits, such that a quantum system would in some ways mirror the classical communication scheme. The quantum key distribution system would include components that create, transmit and detect single polarized photons. The focus of this work is on the development of an efficient single-photon source. This source is comprised of a single quantum dot inside of a photonic crystal microcavity. To better understand the physics behind the device, a computational model is developed. The model uses Finite-Difference Time-Domain methods to analyze the electromagnetic field distribution in photonic crystal microcavities. It uses an 8-band k · p perturbation theory to compute the energy band structure of the epitaxially grown quantum dots. We discuss a method that combines the results of these two calculations for determining the spontaneous emission lifetime of a quantum dot in bulk material or in a microcavity. The computational models developed in this thesis are used to identify and characterize microcavities for potential use in a single-photon source. The computational tools developed are also used to investigate novel photonic crystal microcavities that incorporate 1D distributed Bragg reflectors for vertical confinement. It is found that the spontaneous emission enhancement in the quasi-3D cavities can be significantly greater than in traditional suspended slab

  6. A low-threshold high-index-contrast grating (HCG)-based organic VCSEL

    NASA Astrophysics Data System (ADS)

    Shayesteh, Mohammad Reza; Darvish, Ghafar; Ahmadi, Vahid

    2015-12-01

    We propose a low-threshold high-index-contrast grating (HCG)-based organic vertical-cavity surface-emitting laser (OVCSEL). The device has the feasibility to apply both electrical and optical excitation. The microcavity of the laser is a hybrid photonic crystal (HPC) in which the top distributed Bragg reflector (DBR) is replaced by a sub-wavelength high-contrast-grating layer, and provides a high-quality factor. The simulated quality factor of the microcavity is shown to be as high as 282,000. We also investigate the threshold behavior and the dynamics of the OVCSEL optically pumped with sub-picosecond pulses. Results from numerical simulation show that lasing threshold is 75 nJ/cm2.

  7. A guide to highly effective quality programs.

    PubMed

    Byrnes, John; Fifer, Joe

    2010-01-01

    To dramatically improve quality while decreasing costs, hospitals should: ensure all executives are vocal and visible supporters of quality improvement; focus the board of directors on quality as a strategic priority; strategically target quality resources to improve care for the majority of patients; use the finance system as the foundation for automated quality reporting; form a strong alliance between the CFO and chief quality officer, with each playing a leadership role in the quality program; rely on a well-executed quality program to improve efficiency and decrease the cost of care. PMID:20088475

  8. Synthesis of High-Quality Forsterite

    NASA Astrophysics Data System (ADS)

    Ando, Minato; Himura, Kenji; Tsunooka, Tsutomu; Kagomiya, Isao; Ohsato, Hitoshi

    2007-10-01

    To establish a process that produces high-quality forsterite stably, calcining and sintering conditions were investigated chiefly and two kinds of silica with different forms, and grain sizes were used as starting raw materials. On the basis of the quality factor (\\mathit{Qf}) for forsterite, the sintered samples prepared using powders calcined for 10-24 h, were found to be more stable than those in the case of 2-4 h, and in the case of 24 h of calcination, the samples showed a single phase of forsterite with fine grains. Silica with an amorphous form and a small grain size of 0.25 μm brought a higher \\mathit{Qf} value and a wider permissible temperature range of sintering than silica with a crystalline form and a coarse grain size of 0.82 μm. Concerning the sintering temperature, the sample sintered above 1400 °C showed a high \\mathit{Qf} value. The \\mathit{Qf} value of the sample calcined at 1175 °C for 24 h and sintered at 1450 °C for 2 h using fine-grain amorphous silica of 0.25 μm size, was improved to 219,200 GHz.

  9. An economical route to high quality lubricants

    SciTech Connect

    Andre, J.P.; Hahn, S.K.; Kwon, S.H.; Min, W.

    1996-12-01

    The current rends in the automotive and industrial markets toward more efficient engines, longer drain intervals, and lower emissions all contribute to placing increasingly stringent performance requirements on lubricants. The demand for higher quality synthetic and non-conventional basestocks is expected to grow at a much faster rate than that of conventional lube basestocks to meet these higher performance standards. Yukong Limited has developed a novel technology (the Yukong UCO Lube Process) for the economic production of high quality, high-viscosity-index lube basestocks from a fuels hydrocracker unconverted oil stream. A pilot plant based on this process has been producing oils for testing purposes since May 1994. A commercial facility designed to produce 3,500 BPD of VHVI lube basestocks cane on-stream at Yukong`s Ulsan refinery in October 1995. The Badger Technology Center of Raytheon Engineers and Constructors assisted Yukong during the development of the technology and prepared the basic process design package for the commercial facility. This paper presents process aspects of the technology and comparative data on investment and operating costs. Yukong lube basestock product properties and performance data are compared to basestocks produced by conventional means and by lube hydrocracking.

  10. Tunable open-access microcavities for on-chip cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Potts, C. A.; Melnyk, A.; Ramp, H.; Bitarafan, M. H.; Vick, D.; LeBlanc, L. J.; Davis, J. P.; DeCorby, R. G.

    2016-01-01

    We report on the development of on-chip microcavities and show their potential as a platform for cavity quantum electrodynamics experiments. Microcavity arrays were formed by the controlled buckling of SiO2/Ta2O5 Bragg mirrors and exhibit a reflectance-limited finesse of 3500 and mode volumes as small as 35 λ 3 . We show that the cavity resonance can be thermally tuned into alignment with the D2 transition of 87Rb and outline two methods for providing atom access to the cavity. Owing to their small mode volume and high finesse, these cavities exhibit single-atom cooperativities as high as C 1 = 65 . A unique feature of the buckled-dome architecture is that the strong-coupling parameter g 0 / κ is nearly independent of the cavity size. Furthermore, strong coupling should be achievable with only modest improvements in mirror reflectance, suggesting that these monolithic devices could provide a robust and scalable solution to the engineering of light-matter interfaces.

  11. Unidirectional resonance modes supported by secondary islands in a microcavity comprised of two half-ellipses

    SciTech Connect

    Lee, Jinhyung; Rim, Sunghwan; Cho, Jinhang; Kim, Chil-Min

    2011-03-15

    We propose a simple and robust mechanism to achieve unidirectional emission in a microcavity comprised of two half-ellipses. The microcavity has two geometrical parameters, two eccentricities, which permit a control of the directional emissions. For the microcavity with two small eccentricities, the positions of secondary islands near primary islands in the survival probability distributions determine the directionality of emissions. We obtain the optimized values of the eccentricities for unidirectional emission.

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

    NASA Astrophysics Data System (ADS)

    Vollmer, Frank

    2015-09-01

    as the detection of less than 1 kDa intercalating small molecules[1]. [1] M. D. Baaske, M. R. Foreman, and F. Vollmer, "Single molecule nucleic acid interactions monitored on a label-free microcavity biosensing platform," Nature Nanotechnology, vol. 9, pp. 933-939, 2014. [2] Y. Wu, D. Y. Zhang, P. Yin, and F. Vollmer, "Ultraspecific and Highly Sensitive Nucleic Acid Detection by Integrating a DNA Catalytic Network with a Label-Free Microcavity," Small, vol. 10, pp. 2067-2076, 2014. [3] M. R. Foreman, W.-L. Jin, and F. Vollmer, "Optimizing Detection Limits in Whispering Gallery Mode Biosensing," Optics Express, vol. 22, pp. 5491-5511, 2014. [4] M. A. Santiago-Cordoba, S. V. Boriskina, F. Vollmer, and M. C. Demirel, "Nanoparticle-based protein detection by optical shift of a resonant microcavity," Applied Physics Letters, vol. 99, Aug 2011. [5] M. R. Foreman and F. Vollmer, "Theory of resonance shifts of whispering gallery modes by arbitrary plasmonic nanoparticles," New Journal of Physics, vol. 15, p. 083006, Aug 2013. [6] M. R. Foreman and F. Vollmer "Level repulsion in hybrid photonic-plasmonic microresonators for enhanced biodetection" Phys. Rev. A 88, 023831 (2013).

  13. Document segmentation for high-quality printing

    NASA Astrophysics Data System (ADS)

    Ancin, Hakan

    1997-04-01

    A technique to segment dark texts on light background of mixed mode color documents is presented. This process does not perceptually change graphics and photo regions. Color documents are scanned and printed from various media which usually do not have clean background. This is especially the case for the printouts generated from thin magazine samples, these printouts usually include text and figures form the back of the page, which is called bleeding. Removal of bleeding artifacts improves the perceptual quality of the printed document and reduces the color ink usage. By detecting the light background of the document, these artifacts are removed from background regions. Also detection of dark text regions enables the halftoning algorithms to use true black ink for the black text pixels instead of composite black. The processed document contains sharp black text on white background, resulting improved perceptual quality and better ink utilization. The described method is memory efficient and requires a small number of scan lines of high resolution color documents during processing.

  14. Specific features of the hybridization of Frenkel and Wannier-Mott excitons in a microcavity

    NASA Astrophysics Data System (ADS)

    Dubovskii, O. A.; Agranovich, V. M.

    2016-07-01

    Polariton states have been investigated in a microcavity, where the energy of the Frenkel exciton in an organic quantum well and the energy of the semiconductor Wannier-Mott exciton in an inorganic quantum well are close to the microcavity optical mode. It has been shown that the interaction of each of these excitons with the microcavity optical mode leads to their interaction with each other and to the formation of mutually coupled hybrid excitations. The influence of the location of the quantum wells in a microcavity on the spectra of hybrid states with different polarizations has been analyzed.

  15. Adjustable YAG : Ce3+ photoluminescence from photonic crystal microcavity

    NASA Astrophysics Data System (ADS)

    Li, Yigang; Almeida, Rui M.

    2013-04-01

    Four different photonic bandgap (PBG) structures embedding a YAG : Ce3+ layer inside two three-period Bragg mirrors were prepared by sol-gel processing, forming Fabry-Perot microcavities whose defect peaks moved from red to green. Under irradiation of blue Ar+ laser light, the typical broad YAG : Ce3+ photoluminescence (PL) emission band was highly narrowed in these four samples, with the new position of the modified PL peaks corresponding to the resonance wavelength of each microcavity sample, while the simultaneous colour changes could be easily observed by the human eye. The adjustable range demonstrated here was wide enough to generate white light with colour temperatures from warm white (˜2700 K) to daylight white (˜5600 K), by mixing the modified PL with light from any usual blue LED excitation source. This result provides a novel technique to solve the red-deficiency problem in the white LED industry: instead of relying on the development of new phosphors, the well-known PL of YAG : Ce3+ can be conveniently adjusted by 1D PBG structures.

  16. Light–matter interaction in a microcavity-controlled graphene transistor

    PubMed Central

    Engel, Michael; Steiner, Mathias; Lombardo, Antonio; Ferrari, Andrea C.; Löhneysen, Hilbert v.; Avouris, Phaedon; Krupke, Ralph

    2012-01-01

    Graphene has extraordinary electronic and optical properties and holds great promise for applications in photonics and optoelectronics. Demonstrations including high-speed photodetectors, optical modulators, plasmonic devices, and ultrafast lasers have now been reported. More advanced device concepts would involve photonic elements such as cavities to control light–matter interaction in graphene. Here we report the first monolithic integration of a graphene transistor and a planar, optical microcavity. We find that the microcavity-induced optical confinement controls the efficiency and spectral selection of photocurrent generation in the integrated graphene device. A twenty-fold enhancement of photocurrent is demonstrated. The optical cavity also determines the spectral properties of the electrically excited thermal radiation of graphene. Most interestingly, we find that the cavity confinement modifies the electrical transport characteristics of the integrated graphene transistor. Our experimental approach opens up a route towards cavity-quantum electrodynamics on the nanometre scale with graphene as a current-carrying intra-cavity medium of atomic thickness. PMID:22713748

  17. Microcavity substrates casted from self-assembled microsphere monolayers for spheroid cell culture

    PubMed Central

    Shen, Keyue; Lee, Jungwoo; Yarmush, Martin L.

    2015-01-01

    Multicellular spheroids are an important 3-dimensional cell culture model that reflects many key aspects of in vivo microenvironments. This paper presents a scalable, self-assembly based approach for fabricating microcavity substrates for multicellular spheroid cell culture. Hydrophobic glass microbeads were self-assembled into a tightly packed monolayer through the combined actions of surface tension, gravity, and lateral capillary forces at the water-air interface of a polymer solution. The packed bead monolayer was subsequently embedded in the dried polymer layer. The surface was used as a template for replicating microcavity substrates with perfect spherical shapes. We demonstrated the use of the substrate in monitoring the formation process of tumor spheroids, a proof-of-concept scale-up fabrication procedure into standard microplate formats, and its application in testing cancer drug responses in the context of bone marrow stromal cells. The presented technique offers a simple and effective way of forming high-density uniformlysized spheroids without microfabrication equipment for biological and drug screening applications. PMID:24781882

  18. Method for synthesis of high quality graphene

    DOEpatents

    Lanzara, Alessandra; Schmid, Andreas K.; Yu, Xiaozhu; Hwang, Choonkyu; Kohl, Annemarie; Jozwiak, Chris M.

    2012-03-27

    A method is described herein for the providing of high quality graphene layers on silicon carbide wafers in a thermal process. With two wafers facing each other in close proximity, in a first vacuum heating stage, while maintained at a vacuum of around 10.sup.-6 Torr, the wafer temperature is raised to about 1500.degree. C., whereby silicon evaporates from the wafer leaving a carbon rich surface, the evaporated silicon trapped in the gap between the wafers, such that the higher vapor pressure of silicon above each of the wafers suppresses further silicon evaporation. As the temperature of the wafers is raised to about 1530.degree. C. or more, the carbon atoms self assemble themselves into graphene.

  19. Creating High-Quality Classroom Assignments

    ERIC Educational Resources Information Center

    Matsumura, Lindsay Clare; Gallimore, Ronald

    2005-01-01

    Research indicates that the quality of classroom assignments makes a difference in student learning. Moreover, assignment quality varies between teachers even within the same school and there is room for improvement in many of the assignments that teachers provide to students. Assignment quality, as described in this book, puts into practice…

  20. Design and analysis of photonic crystal micro-cavity based optical sensor platform

    NASA Astrophysics Data System (ADS)

    Goyal, Amit Kumar; Dutta, Hemant Sankar; Pal, Suchandan

    2016-04-01

    In this paper, the design of a two-dimensional photonic crystal micro-cavity based integrated-optic sensor platform is proposed. The behaviour of designed cavity is analyzed using two-dimensional Finite Difference Time Domain (FDTD) method. The structure is designed by deliberately inserting some defects in a photonic crystal waveguide structure. Proposed structure shows a quality factor (Q) of about 1e5 and the average sensitivity of 500nm/RIU in the wavelength range of 1450 - 1580 nm. Sensing technique is based on the detection of shift in upper-edge cut-off wavelength for a reference signal strength of -10 dB in accordance with the change in refractive index of analyte.

  1. Microcavity properties of 2D photonic crystal made by silica matrix doped with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Moukhtari, R.; Hocini, A.; Khedrouche, D.

    2016-01-01

    In this present paper, quality factor of two-dimensional magneto-photonic crystals microcavity fabricated by SiO2/ZrO2 or SiO2/TiO2 matrix doped with magnetic nanoparticles, in which the refractive index varied in the range of 1.51 to 1.58, has been investigated. Finite difference time domain method (3D FDTD) with perfectly matched layers (PML) was used to calculate the transmission spectrum. We demonstrate that the Q factor for the designed cavity increases as the refractive index increases, and found that the Q factor decreases as the volume fraction VF% increases. The obtained results are useful for better designs of magneto photonic crystal devices.

  2. Strong light-matter coupling in plasmonic microcavities

    NASA Astrophysics Data System (ADS)

    Zhang, Lijian; Xi, Fuchun; Xu, Jie; Qian, Qinbai; Gou, Peng; An, Zhenghua

    2014-11-01

    We numerically study the strong coupling between quantum well (QW) intersubband transitions (ISBT) and the plasmonic resonance of metal-dielectric-metal (MDM) microcavities. In this system, the lowest-order energy state of plasmonic resonance is a hybrid mode of propagating surface plasmons (PSP) and localized surface plasmons (LSP). For a given lowest-order resonance, the mode transformation can be realized between PSP mode and LSP mode by varying the plasmonic microcavity structure, which opens a new freedom to modulate the coupling interaction of light and matter. With the cavity mode transforming from LSP mode to PSP mode, the coupling strength increases from 20.75% to 25.75%, which is mainly dominated by the polarization conversion ratio / of plasmonic modes.

  3. Applications of Optical Microcavity Resonators in Analytical Chemistry

    NASA Astrophysics Data System (ADS)

    Wade, James H.; Bailey, Ryan C.

    2016-06-01

    Optical resonator sensors are an emerging class of analytical technologies that use recirculating light confined within a microcavity to sensitively measure the surrounding environment. Bolstered by advances in microfabrication, these devices can be configured for a wide variety of chemical or biomolecular sensing applications. We begin with a brief description of optical resonator sensor operation, followed by discussions regarding sensor design, including different geometries, choices of material systems, methods of sensor interrogation, and new approaches to sensor operation. Throughout, key developments are highlighted, including advancements in biosensing and other applications of optical sensors. We discuss the potential of alternative sensing mechanisms and hybrid sensing devices for more sensitive and rapid analyses. We conclude with our perspective on the future of optical microcavity sensors and their promise as versatile detection elements within analytical chemistry.

  4. Nonlinear resonance-assisted tunneling induced by microcavity deformation

    PubMed Central

    Kwak, Hojeong; Shin, Younghoon; Moon, Songky; Lee, Sang-Bum; Yang, Juhee; An, Kyungwon

    2015-01-01

    Noncircular two-dimensional microcavities support directional output and strong confinement of light, making them suitable for various photonics applications. It is now of primary interest to control the interactions among the cavity modes since novel functionality and enhanced light-matter coupling can be realized through intermode interactions. However, the interaction Hamiltonian induced by cavity deformation is basically unknown, limiting practical utilization of intermode interactions. Here we present the first experimental observation of resonance-assisted tunneling in a deformed two-dimensional microcavity. It is this tunneling mechanism that induces strong inter-mode interactions in mixed phase space as their strength can be directly obtained from a separatrix area in the phase space of intracavity ray dynamics. A selection rule for strong interactions is also found in terms of angular quantum numbers. Our findings, applicable to other physical systems in mixed phase space, make the interaction control more accessible. PMID:25759322

  5. Microcavity-array superhydrophobic surfaces: Limits of the model

    NASA Astrophysics Data System (ADS)

    Salvadori, M. C.; Oliveira, M. R. S.; Spirin, R.; Teixeira, F. S.; Cattani, M.; Brown, I. G.

    2013-11-01

    Superhydrophobic surfaces formed of microcavities can be designed with specific desired advancing and receding contact angles using a new model described by us in prior work. Here, we discuss the limits of validity of the model, and explore the application of the model to surfaces fabricated with small cavities of radius 250 nm and with large cavities of radius 40 μm. The Wenzel model is discussed and used to calculate the advancing and receding contact angles for samples for which our model cannot be applied. We also consider the case of immersion of a sample containing microcavities in pressurized water. A consideration that then arises is that the air inside the cavities can be dissolved in the water, leading to complete water invasion into the cavities and compromising the superhydrophobic character of the surface. Here, we show that this effect does not destroy the surface hydrophobia when the surface is subsequently removed from the water.

  6. Unidirectional emission from a cardioid-shaped microcavity laser.

    PubMed

    Lee, In-Goo; Go, Sung-Min; Ryu, Jin-Hyeok; Yi, Chang-Hwan; Kim, Sung-Bock; Oh, Kwang Ryung; Kim, Chil-Min

    2016-02-01

    We find unidirectional emission in a cardioid-shaped microcavity laser. When a deformation parameter is well adjusted, rays starting around a period-5 unstable periodic orbit emit unidirectionally. To confirm the emission direction, we fabricate a laser by using an InGaAsP semiconductor and investigate emission characteristics. When the laser is excited by current injection with a dc current, resonances localized on the period-5 unstable periodic orbit emit unidirectionally. PMID:26906801

  7. Coupling polariton quantum boxes in sub-wavelength grating microcavities

    SciTech Connect

    Zhang, Bo; Wang, Zhaorong; Deng, Hui; Brodbeck, Sebastian; Kamp, Martin; Schneider, Christian; Höfling, Sven

    2015-02-02

    We report the construction of decoupled, coupled, and quasi-one dimensional polariton systems from zero dimensional polariton quantum boxes using microcavities with sub-wavelength gratings as the top mirror. By designing the tethering patterns around the suspended sub-wavelength gratings, we control the coupling between individual quantum boxes through different optical potentials. Energy levels and real-space or momentum space distributions of the confined modes were measured, which agreed well with simulations.

  8. Multi-objective optimization of microcavity OLEDs with DBR mirror

    NASA Astrophysics Data System (ADS)

    Lu, Albert W.; Chan, J.; Ng, Alan Man Ching; Djurišić, A. B.; Rakić, A. D.

    2007-02-01

    In this work, the emission efficiency and spectral shift with respect to viewing angle were optimized by optimizing the design of the multi-layer top mirror of a microcavity OLED device. We first established criteria for the emission side mirror in order to optimize light intensity and spectral shift with viewing angle. Then we designed mirror using metallic and dielectric layers based on the target defined. The electroluminescence emission spectra of a microcavity OLED consisting of widely used organic materials, N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq 3) as emitting and electron transporting layer was then calculated. Silver was used as the anode and back reflection mirror for the microcavity OLED. The simulation was performed for both the conventional LiF/Al cathode/top mirror and the optimized 5-layered top mirror. Our results indicate that by following the design procedure outlined, we simultaneously optimize the device for better light intensity and spectral shift with viewing angle.

  9. Nonlinear novel oscillation of polaritons in the optical microcavity

    NASA Astrophysics Data System (ADS)

    Zhang, Yongchang; Zhou, Xiangfa; Guo, Guangcan; Zhou, Xingxiang; Pu, Han; Zhou, Zhengwei

    2014-03-01

    As a kind of new state of matter, Bose-Einstein condensation (BEC) in a dilute gas of trapped atoms is able to exhibit quantum phenomena on macroscopic scales. Recently, BEC of microcavity polaritons had been experimentally demonstrated. As a kind of bosonic quasi-particle which generates from the strong light-matter coupling, the polariton can be manipulated by the external laser field, and it provides a platform to simulate strongly correlated many-body models in the photon-coupled microcavity array. In this talk we present a scheme for simulating the nonlinear tunneling between two bosonic condensations in the microcavity system. Due to the controllability of the polariton, the effective nonlinear tunneling between two condensates of polaritons can be easily induced by the external controlling fields. In our work, a kind of two modes polariton model is derived, in which nonlinear tunneling strength depends on the difference of the particles in such two kinds of modes. We investigate the mean-field behaviors for such kind of double-mode polariton model, and we find that it is analogous to the model of the pendulum with variable pendulum length. Furthermore, some novel oscillation modes are revealed.

  10. Lanthanide luminescence enhancements in porous silicon resonant microcavities.

    PubMed

    Jenie, S N Aisyiyah; Pace, Stephanie; Sciacca, Beniamino; Brooks, Robert D; Plush, Sally E; Voelcker, Nicolas H

    2014-08-13

    In this paper, the covalent immobilization and luminescence enhancement of a europium (Eu(III)) complex in a porous silicon (pSi) layer with a microcavity (pSiMC) structure are demonstrated. The alkyne-pendant arm of the Eu(III) complex was covalently immobilized on the azide-modified surface via ligand-assisted "click" chemistry. The design parameters of the microcavity were optimized to obtain an efficient luminescence-enhancing device. Luminescence enhancements by a factor of 9.5 and 3.0 were observed for Eu(III) complex bound inside the pSiMC as compared to a single layer and Bragg reflector of identical thickness, respectively, confirming the increased interaction between the immobilized molecules and the electric field in the spacer of the microcavity. When comparing pSiMCs with different resonance wavelength position, luminescence was enhanced when the resonance wavelength overlapped with the maximum emission wavelength of the Eu(III) complex at 614 nm, allowing for effective coupling between the confined light and the emitting molecules. The pSiMC also improved the spectral color purity of the Eu(III) complex luminescence. The ability of a pSiMC to act as an efficient Eu(III) luminescence enhancer, combined with the resulting sharp linelike emission, can be exploited for the development of ultrasensitive optical biosensors. PMID:25032481

  11. Integrating Quality into the Textile and Apparel High School Curriculum.

    ERIC Educational Resources Information Center

    Meyer, Deborah J. C.; Kadolph, Sara J.; Cosbey, Sarah; Hillery, Julie; Haar, Sherry; Day, Marla; Keiser, Sandra; Brandes, Kendra

    2001-01-01

    Explains the importance of quality assurance in high school textiles and apparel instruction. Describes educational activities that integrate quality assurance concepts (teamwork, continuous improvement, customer focus, and empowerment). (Contains 23 references.) (SK)

  12. High Efficiency, Illumination Quality OLEDs for Lighting

    SciTech Connect

    Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

    2008-03-31

    The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown. In

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

    SciTech Connect

    Grudinkin, S. A. Dontsov, A. A.; Feoktistov, N. A.; Baranov, M. A.; Bogdanov, K. V.; Averkiev, N. S.; Golubev, V. G.

    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.

  14. Generation of high-quality petawatt pulses

    SciTech Connect

    Mourou, G; Bado, Philippe

    1991-01-01

    CPA sources need a front-end capable of generating very short seed pulses. To meet this requirement, present CPA sources rely on actively modelocked solid-state oscillators used in conjunction with non-linear fiber stages. This approach generates pulses with a residual frequency chirp, resulting in a limited peak-to-background intensity contrast ratio. The availability of an oscillator capable of producing directly (i.e. without fiber stage) picosecond or sub-picosecond pulses would significantly improve the quality of CPA sources. We have pursued different approaches to replace the standard modelocked oscillator front-end. In an initial phase, we investigated the possible use of Additive Pulse Modelocking (APM) color-center lasers as oscillators for CPA Nd:glass sources. Lately we have developed a Ti:Sapphire modelocked oscillator operating in the one-micron range. In order to generate pulses with very high peak to background contrast ratio, we have built a non-linear coupled-cavity oscillator generating 200-fs pulses. This color-center laser operates in the 1.5--1.6 micron range. A diagram of the oscillator is shown in Fig. 1. The laser is pumped with a modelocked Nd:YAG source. Both KCl and NaCl crystals were tested as gain media. NaCl was found to have a larger tuning range and to generate a higher average power (up to 150 mW). When synchronously mode-locked, the color-center generates pulses in the 10--20 ps range. Once interferometrically coupled to non-linear external-cavity, this oscillator produces very short pulses (85 to 260 fs). This oscillator was first operated with a 2 mm birefringent plate. 85 fs, near transform-limited pulses were generated at 1.54 micron. As the laser was tuned to longer wavelength, the pulse duration increased, as well as the bandwidth-duration product. With a 4 mm birefringent plate, 125 fs, transform-limited pulses were generated over the full tuning range.

  15. All-optical diode structure based on asymmetrical coupling by a micro-cavity and FP cavity at two sides of photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Liu, Yun-Feng; Jia, Chen; He, Xing-Dao

    2016-06-01

    A high efficiency all-optical diode based on photonic crystal (PC) waveguide has been proposed and numerically investigated by finite-difference time-domain (FDTD) method. The structure is asymmetrically coupled by a micro-cavity containing nonlinear Kerr medium and a FP cavity at sides of PC waveguide. Because of interference between two cavities, Fano peak and FP peak can both appear in transmission spectra and unidirectional transmission can be achieved. The working wavelength can set between two peaks and near to the Fano peak. For forward launch with suitable light intensity, nonlinear Kerr effect of micro-cavity can been excited. It will result in red shift of Fano peak and achieving forward transmission. But for backward launch, a stronger incidence light is needed to the excite Kerr effect due to the design of asymmetric structure. This design has many advantages, including high maximum transmittance, high transmittance contrast ratio, low power threshold, short response time, and ease of integration.

  16. Enhanced nonlinear optics in coupled optical microcavities with an unbroken and broken parity-time symmetry

    NASA Astrophysics Data System (ADS)

    Li, Jiahua; Zhan, Xiaogui; Ding, Chunling; Zhang, Duo; Wu, Ying

    2015-10-01

    We present a perturbation technique to study the linear and nonlinear output characteristics of coherent photon transport in a parity-time (PT )-symmetric double-microcavity system where one passive cavity contains a single quantum emitter. It is found that (i) for the linear transmission of a low-power input probe field, the output spectra of the proposed PT -symmetric system exhibit a single transparent resonance dip and two symmetric, strongly amplifying sidebands, i.e., an inverted dipole-induced transparency; and (ii) for the nonlinear transmission of the input probe field, giant optical third-order nonlinearities with high linear transmission rate and vanishing nonlinear absorption can be achieved efficiently when the system parameters are tuned properly so that a PT -symmetry phase transition occurs. The obtained results can be useful for quantum information processing, quantum nondemolition measurements of photons, and optical signal processing.

  17. Hybrid quantum gates between flying photon and diamond nitrogen-vacancy centers assisted by optical microcavities

    PubMed Central

    Wei, Hai-Rui; Lu Long, Gui

    2015-01-01

    Hybrid quantum gates hold great promise for quantum information processing since they preserve the advantages of different quantum systems. Here we present compact quantum circuits to deterministically implement controlled-NOT, Toffoli, and Fredkin gates between a flying photon qubit and diamond nitrogen-vacancy (NV) centers assisted by microcavities. The target qubits of these universal quantum gates are encoded on the spins of the electrons associated with the diamond NV centers and they have long coherence time for storing information, and the control qubit is encoded on the polarizations of the flying photon and can be easily manipulated. Our quantum circuits are compact, economic, and simple. Moreover, they do not require additional qubits. The complexity of our schemes for universal three-qubit gates is much reduced, compared to the synthesis with two-qubit entangling gates. These schemes have high fidelities and efficiencies, and they are feasible in experiment. PMID:26271899

  18. A compact photonic crystal micro-cavity on a single-mode lithium niobate photonic wire

    NASA Astrophysics Data System (ADS)

    Cai, Lutong; Zhang, Shaomei; Hu, Hui

    2016-03-01

    The properties of the guided modes, including the single-mode conditions and the coupling of different polarized modes in the single-crystal lithium niobate photonic wires, were analyzed in detail. One-dimensional photonic crystal micro-cavities with several different patterns, which could be used as an ultra-compact optical filter, were designed and simulated in order to get high transmission at the resonant wavelength and the best preferment. The designed structure, with the whole size of 6.5 × 0.7 μm2, was fabricated on a single-mode photonic wire. A measured peak transmission of 0.34 at 1400 nm, an extinction ratio of 12.5 dB and a Q factor of 156 were obtained. The measured transmission spectrum was basically consistent with the simulation, although a slight shift of resonant wavelength occurred due to the fabrication errors.

  19. Looking through the mirror: optical microcavity-mirror image photonic interaction.

    PubMed

    Shi, Lei; Xifré-Pérez, E; García de Abajo, F J; Meseguer, F

    2012-05-01

    Although science fiction literature and art portray extraordinary stories of people interacting with their images behind a mirror, we know that they are not real and belong to the realm of fantasy. However, it is well known that charges or magnets near a good electrical conductor experience real attractive or repulsive forces, respectively, originating in the interaction with their images. Here, we show strong interaction between an optical microcavity and its image under external illumination. Specifically, we use silicon nanospheres whose high refractive index makes well-defined optical resonances feasible. The strong interaction produces attractive and repulsive forces depending on incident wavelength, cavity-metal separation and resonance mode symmetry. These intense repulsive photonic forces warrant a new kind of optical levitation that allows us to accurately manipulate small particles, with important consequences for microscopy, optical sensing and control of light by light at the nanoscale. PMID:22565747

  20. Thermomagnetic writing into magnetophotonic microcavities controlling thermal diffusion for volumetric magnetic holography.

    PubMed

    Isogai, Ryosuke; Nakamura, Yuichi; Takagi, Hiroyuki; Goto, Taichi; Lim, Pang Boey; Inoue, Mitsuteru

    2016-01-11

    Holographic memory is expected to become a high-capacity data storage. Magnetic volumetric holograms are rewritable holograms that are recorded as magnetization directions through thermomagnetic recording. However, the effective depth of magnetic holograms is limited by thermal diffusion that causes merging of magnetic fringes. In this study, we propose the insertion of heat-sink layers (HSLs) for retaining well-defined magnetic fringes during volumetric writing. Magnetophotonic microcavity media were used for demonstrating the HSL effect, and the structural design principle was established in numerical calculations. The results indicate that deep and clear magnetic fringes and an improvement in the diffraction efficiency can be achieved by the insertion of HSLs. PMID:26832282

  1. Far off-resonant coupling between photonic crystal microcavity and single quantum dot with resonant excitation

    SciTech Connect

    Banihashemi, Mehdi; Ahmadi, Vahid; Nakamura, Tatsuya; Kojima, Takanori; Kojima, Kazunobu; Noda, Susumu

    2013-12-16

    In this paper, we experimentally demonstrate that with sub-nanowatt coherent s-shell excitation of a single InAs quantum dot, off-resonant coupling of 4.1 nm is possible between L3 photonic crystal microcavity and the quantum dot at 50 K. This resonant excitation reduces strongly the effect of surrounding charges to quantum dot, multiexciton complexes and pure dephasing. It seems that this far off-resonant coupling is the result of increased number of acoustical phonons due to high operating temperature of 50 K. The 4.1 nm detuning is the largest amount for this kind of coupling.

  2. Quality.

    ERIC Educational Resources Information Center

    Evans, Judith L.; Schaeffer, Sheldon

    1996-01-01

    This issue of the Coordinator's Notebook focuses on the quality of Early Childhood Care and Development (ECCD) programs. The bulk of the issue is devoted to an article "Quality in ECCD: Everyone's Concern" (Judith Evans), which reviews the need for a definition of high quality in ECCD programs and discusses how diverse stakeholders define quality.…

  3. Spatiotemporal Chaos Induces Extreme Events in an Extended Microcavity Laser

    NASA Astrophysics Data System (ADS)

    Selmi, F.; Coulibaly, S.; Loghmari, Z.; Sagnes, I.; Beaudoin, G.; Clerc, M. G.; Barbay, S.

    2016-01-01

    Extreme events such as rogue waves in optics and fluids are often associated with the merging dynamics of coherent structures. We present experimental and numerical results on the physics of extreme event appearance in a spatially extended semiconductor microcavity laser with an intracavity saturable absorber. This system can display deterministic irregular dynamics only, thanks to spatial coupling through diffraction of light. We have identified parameter regions where extreme events are encountered and established the origin of this dynamics in the emergence of deterministic spatiotemporal chaos, through the correspondence between the proportion of extreme events and the dimension of the strange attractor.

  4. Theory of optical spin control in quantum dot microcavities

    NASA Astrophysics Data System (ADS)

    Smirnov, D. S.; Glazov, M. M.; Ivchenko, E. L.; Lanco, L.

    2015-09-01

    We present a microscopic theory of optical initialization, control, and detection for a single electron spin in a quantum dot embedded into a zero-dimensional microcavity. The strong coupling regime of the trion and the cavity mode is addressed. We demonstrate that efficient spin orientation by a single circularly polarized pulse is possible in relatively weak transverse magnetic fields. The possibilities for spin control by additional circularly polarized pulse are analyzed. Under optimal conditions the Kerr and Faraday rotation angles induced by the spin polarized electron may reach tens of degrees.

  5. Ring-shaped polariton lasing in pillar microcavities

    SciTech Connect

    Kalevich, V. K. Afanasiev, M. M.; Lukoshkin, V. A.; Kavokin, K. V.; Tsintzos, S. I.; Savvidis, P. G.; Kavokin, A. V.

    2014-03-07

    Optically generated exciton-polaritons in cylindric semiconductor pillar microcavity with embedded GaAs/AlGaAs quantum wells demonstrate a clear polariton lasing regime. When exciting in the center of the pillar, we detect a ring-shaped emission, where the peak of intensity can be separated from the excitation spot by more than 10 μm. The spatial coherence of the ring emission is verified by interferometry measurements. These observations are interpreted by drift of the exciton polariton condensate away from the excitation spot due to its repulsion from the exciton reservoir and by its spatial confinement by the pillar boundary.

  6. Polaritons in a nonideal periodic array of microcavities

    NASA Astrophysics Data System (ADS)

    Rumyantsev, Vladimir; Fedorov, Stanislav; Gumennyk, Kostyantyn; Sychanova, Marina; Kavokin, Alexey

    2016-01-01

    The virtual crystal approximation is employed to numerically model the propagation of localized electromagnetic excitations through a two-dimensional array of coupled microcavities containing atomic clusters (quantum dots). The constructed model allows for the presence of defects (absence of cavities and/or quantum dots) at certain sites of the supercrystal. We derive the dispersion relations for polaritonic modes as functions of defect concentrations. This permits to evaluate the densities of states of polaritons and their effective masses as well as the band gaps for any prescribed values of defect concentrations.

  7. Development of a deformation-tunable quadrupolar microcavity

    NASA Astrophysics Data System (ADS)

    Yang, Juhee; Moon, Songky; Lee, Sang-Bum; Lee, Jai-Hyung; An, Kyungwon; Shim, Jeong-Bo; Lee, Hai-Woong; Kim, Sang-Wook

    2006-08-01

    We have developed a technique for realizing a two-dimensional quadrupolar microcavity with its deformation variable from 0% to 20% continuously. We employed a microjet ejected from a noncircular orifice in order to generate a stationary column with modulated quadrupolar deformation in its cross section. Wavelength redshifts of low-order cavity modes due to shape deformation were measured and were found to be in good agreement with the wave calculation for the same deformation, indicating that the observed deformation is quadrupolar in nature.

  8. Resonant self-pulsations in coupled nonlinear microcavities

    SciTech Connect

    Grigoriev, Victor; Biancalana, Fabio

    2011-04-15

    A different point of view on the phenomenon of self-pulsations is presented, which shows that they are a balanced state formed by two counteracting processes: beating of modes and bistable switching. A structure based on two coupled nonlinear microcavities provides a generic example of a system with enhanced ability to support this phenomenon. The specific design of such a structure in the form of multilayered media is proposed, and the coupled-mode theory is applied to describe its dynamical properties. It is emphasized that the frequency of self-pulsations is related to the frequency splitting between resonant modes and can be adjusted over a broad range.

  9. Spatiotemporal Chaos Induces Extreme Events in an Extended Microcavity Laser.

    PubMed

    Selmi, F; Coulibaly, S; Loghmari, Z; Sagnes, I; Beaudoin, G; Clerc, M G; Barbay, S

    2016-01-01

    Extreme events such as rogue waves in optics and fluids are often associated with the merging dynamics of coherent structures. We present experimental and numerical results on the physics of extreme event appearance in a spatially extended semiconductor microcavity laser with an intracavity saturable absorber. This system can display deterministic irregular dynamics only, thanks to spatial coupling through diffraction of light. We have identified parameter regions where extreme events are encountered and established the origin of this dynamics in the emergence of deterministic spatiotemporal chaos, through the correspondence between the proportion of extreme events and the dimension of the strange attractor. PMID:26799020

  10. Quality evaluation of extra high quality images based on key assessment word

    NASA Astrophysics Data System (ADS)

    Kameda, Masashi; Hayashi, Hidehiko; Akamatsu, Shigeru; Miyahara, Makoto M.

    2001-06-01

    An all encompassing goal of our research is to develop an extra high quality imaging system which is able to convey a high level artistic impression faithfully. We have defined a high order sensation as such a high level artistic impression, and it is supposed that the high order sensation is expressed by the combination of the psychological factor which can be described by plural assessment words. In order to pursue the quality factors that are important for the reproduction of the high order sensation, we have focused on the image quality evaluation of the extra high quality images using the assessment words considering the high order sensation. In this paper, we have obtained the hierarchical structure between the collected assessment words and the principles of European painting based on the conveyance model of the high order sensation, and we have determined a key assessment word 'plasticity' which is able to evaluate the reproduction of the high order sensation more accurately. The results of the subjective assessment experiments using the prototype of the developed extra high quality imaging system have shown that the obtained key assessment word 'plasticity' is the most appropriate assessment word to evaluate the image quality of the extra high quality images quasi-quantitatively.

  11. Quality Assurance Strategy for Existing Homes. Final Quality Management Primer for High Performing Homes

    SciTech Connect

    Del Bianco, M.; Taggart, J.; Sikora, J.; Wood, A.

    2012-12-01

    This guide is designed to help Building America (BA) teams understand quality management and its role in transitioning from conventional to high performance home building and remodeling. It explains what quality means, the value of quality management systems, the unique need for QMS when building high performing homes, and the first steps to a implementing a comprehensive QMS. This document provides a framework and context for BA teams when they encounter builders and remodelers.

  12. Quality Assurance Strategy for Existing Homes: Final Quality Management Primer for High Performing Homes

    SciTech Connect

    Del Bianco, M.; Taggart, J.; Sikora, J.; Wood, A.

    2012-12-01

    This guide is designed to help Building America (BA) Teams understand quality management and its role in transitioning from conventional to high performance home building and remodeling. It explains what quality means, the value of quality management systems, the unique need for QMS when building high performing homes, and the first steps to a implementing a comprehensive QMS. This document provides a framework and context for BA teams when they encounter builders and remodelers.

  13. Strategies that promote high quality care in Indonesia

    PubMed Central

    Gertler, Paul J.

    2009-01-01

    Objectives To investigate factors predicting the quality of care received using a nationally representative dataset from Indonesia. Data Sources The study combines two surveys in 13 provinces: a household survey of 2451 women who delivered a live birth in 1992-1998, and a facility survey that measured quality available from outpatient providers. Study design Multivariate regressions are used to explain the quality of care received. Explanatory variables are high facility quality, maternal education, household wealth, ethnicity, and insurance. Data collection methods Facility quality available is measured by adherence to prenatal protocols using a clinical case scenario. Quality received is measured by maternal reports about routine prenatal services received. Principle findings High facility quality predicts an increase in quality received. Although poor households have access to the same or higher quality care compared with the least poor, the poor receive lower levels of quality. In remote regions, quality received rises with increasing levels of maternal education and household wealth. Conclusions Improving health provider knowledge, and increasing household financial resources and information could redress inequalities in quality received among the poor and least educated. PMID:18501988

  14. Toward automatic recognition of high quality clinical evidence.

    PubMed

    Kilicoglu, Halil; Demner-Fushman, Dina; Rindflesch, Thomas C; Wilczynski, Nancy L; Haynes, R Brian

    2008-01-01

    Automatic methods for recognizing topically relevant documents supported by high quality research can assist clinicians in practicing evidence-based medicine. We approach the challenge of identifying articles with high quality clinical evidence as a binary classification problem. Combining predictions from supervised machine learning methods and using deep semantic features, we achieve 73.5% precision and 67% recall. PMID:18998881

  15. High-Quality Curriculum: A Lesson in Collaboration

    ERIC Educational Resources Information Center

    Beasley, Jennifer G.

    2012-01-01

    The Curriculum Studies Network focuses on promoting and creating high-quality curriculum to meet the needs of academically advanced learners. Staff at Curriculum Studies Network are proud of the collaboration they promote among educators, but in order for high-quality curriculum to continue to be the standard in the field, they realize the…

  16. Inequality in Preschool Quality? Community-Level Disparities in Access to High-Quality Learning Environments

    ERIC Educational Resources Information Center

    Bassok, Daphna; Galdo, Eva

    2016-01-01

    In recent years, unequal access to high-quality preschool has emerged as a growing public policy concern. Because of data limitations, it is notoriously difficult to measure disparities in access to early learning opportunities across communities and particularly challenging to quantify gaps in access to "high-quality" programs. Research…

  17. Vertical Single-Crystalline Organic Nanowires on Graphene: Solution-Phase Epitaxy and Optical Microcavities.

    PubMed

    Zheng, Jian-Yao; Xu, Hongjun; Wang, Jing Jing; Winters, Sinéad; Motta, Carlo; Karademir, Ertuğrul; Zhu, Weigang; Varrla, Eswaraiah; Duesberg, Georg S; Sanvito, Stefano; Hu, Wenping; Donegan, John F

    2016-08-10

    Vertically aligned nanowires (NWs) of single crystal semiconductors have attracted a great deal of interest in the past few years. They have strong potential to be used in device structures with high density and with intriguing optoelectronic properties. However, fabricating such nanowire structures using organic semiconducting materials remains technically challenging. Here we report a simple procedure for the synthesis of crystalline 9,10-bis(phenylethynyl) anthracene (BPEA) NWs on a graphene surface utilizing a solution-phase van der Waals (vdW) epitaxial strategy. The wires are found to grow preferentially in a vertical direction on the surface of graphene. Structural characterization and first-principles ab initio simulations were performed to investigate the epitaxial growth and the molecular orientation of the BPEA molecules on graphene was studied, revealing the role of interactions at the graphene-BPEA interface in determining the molecular orientation. These free-standing NWs showed not only efficient optical waveguiding with low loss along the NW but also confinement of light between the two end facets of the NW forming a microcavity Fabry-Pérot resonator. From an analysis of the optical dispersion within such NW microcavities, we observed strong slowing of the waveguided light with a group velocity reduced to one-tenth the speed of light. Applications of the vertical single-crystalline organic NWs grown on graphene will benefit from a combination of the unique electronic properties and flexibility of graphene and the tunable optical and electronic properties of organic NWs. Therefore, these vertical organic NW arrays on graphene offer the potential for realizing future on-chip light sources. PMID:27438189

  18. Interaction of coherent confined optical modes in neighboring 3D cylindrical ZnO microcavities

    SciTech Connect

    Gruzintsev, A. N. Volkov, V. T.; Knyazev, M. A.; Yakimov, E. E.

    2006-11-15

    Luminescent properties of pairs of neighboring variously spaced 3D cylindrical ZnO microcavities 1.8 {mu}m in diameter, produced by electron-beam lithography and reactive ion etching, are studied. Narrow luminescence peaks in the ZnO exciton spectral region, related to single-mode lasing, were observed. The energy of exchange interaction of coupled modes of two microcavities was calculated as a function of the intercavity distance. Broadening of the line of stimulated UV luminescence associated with coupled photonic modes of two microcavities was observed as the intercavity distance decreased.

  19. Enhanced out-coupling factor of microcavity organic light-emitting devices with irregular microlens array

    NASA Astrophysics Data System (ADS)

    Lim, Jongsun; Oh, Seung Seok; Youp Kim, Doo; Cho, Sang Hee; Kim, In Tae; Han, S. H.; Takezoe, Hideo; Choi, Eun Ha; Cho, Guang Sup; Seo, Yoon Ho; Oun Kang, Seung; Park, Byoungchoo

    2006-07-01

    We studied microcavity organic light-emitting devices with a microlens system. A microcavity for organic light-emitting devices (OLED) was fabricated by stacks of SiO2 and SiNx layers and a metal cathode together with the microlens array. Electroluminescence of the devices showed that color variation under the viewing angle due to the microcavity is suppressed remarkably by microlens arrays, which makes the use of devices acceptable in many applications. It was also demonstrated that the external out-coupling factor of the devise increases by a factor of ~1.8 with wide viewing angles compared to conventional OLEDs.

  20. Enhanced out-coupling factor of microcavity organic light-emitting devices with irregular microlens array.

    PubMed

    Lim, Jongsun; Oh, Seung Seok; Kim, Doo Youp; Cho, Sang Hee; Kim, In Tae; Han, S H; Takezoe, Hideo; Choi, Eun Ha; Cho, Guang Sup; Seo, Yoon Ho; Kang, Seung Oun; Park, Byoungchoo

    2006-07-10

    We studied microcavity organic light-emitting devices with a microlens system. A microcavity for organic light-emitting devices (OLED) was fabricated by stacks of SiO(2) and SiN(x) layers and a metal cathode together with the microlens array. Electroluminescence of the devices showed that color variation under the viewing angle due to the microcavity is suppressed remarkably by microlens arrays, which makes the use of devices acceptable in many applications. It was also demonstrated that the external out-coupling factor of the devise increases by a factor of ~1.8 with wide viewing angles compared to conventional OLEDs. PMID:19516834

  1. Narrow dark polariton due to coupled coherence in a quantum well microcavity

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Cui Li; Zhang, Rui; Zhuo, Zhong Chang; Su, Xue Mei

    2015-10-01

    A scheme is proposed to obtain slow light in a coulped quantum wells microcavity with tunneling induced transparency between intersubband electronic transitions. Three prolaritons are created by intracavity Fano interference between fundamental mode photon and two quantum oscillators of coherent subband electronic excitations. A narrow middle dark polariton of the three can be produced, which can be used to suppress the line profiles of the transmission or reflection spectra for the incident light. This leads to slow propagation of the incident light in the microcavity. The semiconductor optical microcavity can be an alternative choice of quantum photoelectronic devices in nanoscale.

  2. Composite modulation of Fano resonance in plasmonic microstructures by electric-field and microcavity

    SciTech Connect

    Zhang, Fan; Wu, Chenyun; Yang, Hong; Hu, Xiaoyong Gong, Qihuang

    2014-11-03

    Composite modulation of Fano resonance by using electric-field and microcavity simultaneously is realized in a plasmonic microstructure, which consists of a gold nanowire grating inserted into a Fabry-Perot microcavity composited of a liquid crystal layer sandwiched between two indium tin oxide layers. The Fano resonance wavelength varies with the applied voltage and the microcavity resonance. A large shift of 48 nm in the Fano resonance wavelength is achieved when the applied voltage is 20 V. This may provide a new way for the study of multi-functional integrated photonic circuits and chips based on plasmonic microstructures.

  3. 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.

  4. Homoepitaxial nonpolar (10-10) ZnO/ZnMgO monolithic microcavities: Towards reduced photonic disorder

    NASA Astrophysics Data System (ADS)

    Zuniga-Perez, J.; Kappei, L.; Deparis, C.; Reveret, F.; Grundmann, M.; de Prado, E.; Jamadi, O.; Leymarie, J.; Chenot, S.; Leroux, M.

    2016-06-01

    Nonpolar ZnO/ZnMgO-based optical microcavities have been grown on (10-10) m-plane ZnO substrates by plasma-assisted molecular beam epitaxy. Reflectivity measurements indicate an exponential increase of the cavity quality factor with the number of layers in the distributed Bragg reflectors. Most importantly, microreflectivity spectra recorded with a spot size in the order of 2 μm show a negligible photonic disorder (well below 1 meV), leading to local quality factors equivalent to those obtained by macroreflectivity. The anisotropic character of the nonpolar heterostructures manifests itself both in the surface features, elongated parallel to the in-plane c direction, and in the optical spectra, with two cavity modes being observed at different energies for orthogonal polarizations.

  5. Total quality management: A management philosophy for providing high quality construction

    NASA Astrophysics Data System (ADS)

    Beckwith, Paul D.

    Total Quality Management (TQM) is not a new concept. Only recently (within the past ten years or so) have American companies started to realize the potential of TQM as a means of ensuring high quality products and services. With this realization has come implementation in manufacturing and service companies. A commercial construction company, like any other business, must provide a top quality finished product to its customer if it intends to stay in business. TQM is one way to work to that end. This report explores the quality problems facing my fictitious construction company, which I believe are fairly typical among the commercial construction industry, existing management methods, and the TQM method to ensure top quality production. It will be shown why I believe TQM or a variation thereof is the best method for controlling the quality of products and service during the construction process. Under the philosophy of TQM, we build quality into the finished product.

  6. High-quality work, job satisfaction, and occupational injuries.

    PubMed

    Barling, Julian; Kelloway, E Kevin; Iverson, Roderick D

    2003-04-01

    The authors investigated whether and how 1 element of a high-performance work system, namely high-quality jobs (composed of extensive training, variety, and autonomy), affects occupational injuries. On the basis of data from the Australian WIRS95 database (N = 16,466; Department of Workplace Relations and Small Business, 1997), high-quality jobs exerted a direct effect on injuries and an indirect effect through the mediating influence of job satisfaction. Conceptual, methodological, and practical issues are discussed. PMID:12731711

  7. Boiler for generating high quality vapor

    NASA Technical Reports Server (NTRS)

    Gray, V. H.; Marto, P. J.; Joslyn, A. W.

    1972-01-01

    Boiler supplies vapor for use in turbines by imparting a high angular velocity to the liquid annulus in heated rotating drum. Drum boiler provides a sharp interface between boiling liquid and vapor, thereby, inhibiting the formation of unwanted liquid droplets.

  8. Light manipulation with Bacteriorhodopsin membrane self-assembled on high-Q photonic structures

    NASA Astrophysics Data System (ADS)

    Vollmer, Frank

    2008-03-01

    Resonant photonic structures such as ring resonators and photonic crystal nanocavities interact evanescently with biological material assembled on a reflecting interface. Quality (Q-) factors ˜10^6 and sub-wavelength modal (V-) volumes significantly enhance the interaction so that tuning of microcavity resonances by only few molecules is feasible. Since only few constituents are required, the molecular-photonic interface can be fashioned from self-organizing principles that govern interaction of organic and biological polymers. We demonstrate this bottom-up approach with photochromic Bacteriorhodopsin membrane which we self-assemble on various microcavities. The hybrid molecular-photonic architectures exhibit high Q/V-values and are sensitive to photoinduced molecular transitions and other non-linearities which we utilize for demonstrations of all-optical switching, routing and molecular analysis.

  9. Highly Integrated Quality Assurance – An Empirical Case

    SciTech Connect

    Drake Kirkham; Amy Powell; Lucas Rich

    2011-02-01

    Highly Integrated Quality Assurance – An Empirical Case Drake Kirkham1, Amy Powell2, Lucas Rich3 1Quality Manager, Radioisotope Power Systems (RPS) Program, Idaho National Laboratory, P.O. Box 1625 M/S 6122, Idaho Falls, ID 83415-6122 2Quality Engineer, RPS Program, Idaho National Laboratory 3Quality Engineer, RPS Program, Idaho National Laboratory Contact: Voice: (208) 533-7550 Email: Drake.Kirkham@inl.gov Abstract. The Radioisotope Power Systems Program of the Idaho National Laboratory makes an empirical case for a highly integrated Quality Assurance function pertaining to the preparation, assembly, testing, storage and transportation of 238Pu fueled radioisotope thermoelectric generators. Case data represents multiple campaigns including the Pluto/New Horizons mission, the Mars Science Laboratory mission in progress, and other related projects. Traditional Quality Assurance models would attempt to reduce cost by minimizing the role of dedicated Quality Assurance personnel in favor of either functional tasking or peer-based implementations. Highly integrated Quality Assurance adds value by placing trained quality inspectors on the production floor side-by-side with nuclear facility operators to enhance team dynamics, reduce inspection wait time, and provide for immediate, independent feedback. Value is also added by maintaining dedicated Quality Engineers to provide for rapid identification and resolution of corrective action, enhanced and expedited supply chain interfaces, improved bonded storage capabilities, and technical resources for requirements management including data package development and Certificates of Inspection. A broad examination of cost-benefit indicates highly integrated Quality Assurance can reduce cost through the mitigation of risk and reducing administrative burden thereby allowing engineers to be engineers, nuclear operators to be nuclear operators, and the cross-functional team to operate more efficiently. Applicability of this case

  10. The Equitable Distribution of High-Quality Teachers

    ERIC Educational Resources Information Center

    Bumgardner, Stan

    2010-01-01

    A new report by the National Comprehensive Center for Teacher Quality (TQ Center) highlights efforts across the nation to address a key point in the No Child Left Behind law and the American Recovery and Reinvestment Act (ARRA)--the equitable distribution of high-quality teachers across all schools. Research consistently has pointed to effective…

  11. Can high quality cane be delivered to the mill economically

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cane quality is becoming increasingly important to the Louisiana sugarcane industry, with some processors offering premiums for high quality cane. Using a Cameco® 3500, we tested ground speeds of 2.5, 3.0, and 3.5 mph and fan speeds of 650, 850, and 1050 rpm. Ground speed had no effect on can...

  12. Microcavity design for low threshold polariton condensation with ultrashort optical pulse excitation

    SciTech Connect

    Poellmann, C.; Leierseder, U.; Huber, R.; Galopin, E.; Lemaître, A.; Amo, A.; Bloch, J.; Ménard, J.-M.

    2015-05-28

    We present a microcavity structure with a shifted photonic stop-band to enable efficient non-resonant injection of a polariton condensate with spectrally broad femtosecond pulses. The concept is demonstrated theoretically and confirmed experimentally for a planar GaAs/AlGaAs multilayer heterostructure pumped with ultrashort near-infrared pulses while photoluminescence is collected to monitor the optically injected polariton density. As the excitation wavelength is scanned, a regime of polariton condensation can be reached in our structure at a consistently lower fluence threshold than in a state-of-the-art conventional microcavity. Our microcavity design improves the polariton injection efficiency by a factor of 4, as compared to a conventional microcavity design, when broad excitation pulses are centered at a wavelength of λ = 740 nm. Most remarkably, this improvement factor reaches 270 when the excitation wavelength is centered at 750 nm.

  13. Light diffusing effects of nano and micro-structures on OLED with microcavity.

    PubMed

    Cho, Doo-Hee; Shin, Jin-Wook; Joo, Chul Woong; Lee, Jonghee; Park, Seung Koo; Moon, Jaehyun; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong-Ik

    2014-10-20

    We examined the light diffusing effects of nano and micro-structures on microcavity designed OLEDs. The results of FDTD simulations and experiments showed that the pillar shaped nano-structure was more effective than the concave micro-structure for light diffusing of microcavity OLEDs. The sharp luminance distribution of the microcavity OLED was changed to near Lambertian luminance distribution by the nano-structure, and light diffusing effects increased with the height of the nano-structure. Furthermore, the nano-structure has advantages including light extraction of the substrate mode, reproducibility of manufacturing process, and minimizing pixel blur problems in an OLED display panel. The nano-structure is a promising candidate for a light diffuser, resolving the viewing angle problems in microcavity OLEDs. PMID:25607307

  14. Microcavity array plasma system for remote chemical processing at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Lee, Dae-Sung; Hamaguchi, Satoshi; Sakai, Osamu; Park, Sung-Jin; Eden, J. Gary

    2012-06-01

    A microplasma system designed for chemical processing at atmospheric pressure is fabricated and characterized with flowing He/O2 gas mixtures. At the heart of this microcavity dielectric barrier discharge (MDBD) system are two arrays of half-ellipsoidal microcavities engraved by micropowder blasting into dielectric surfaces facing a flowing, low-temperature plasma. Experiments demonstrate that the ignition voltage is reduced, and the spatially averaged optical emission is doubled, for an MDBD flowing plasma array relative to an equivalent system having no microcavities. As an example of the potential of flowing atmospheric microplasma systems for chemical processing, the decomposition of methylene blue (as evidenced by decoloration at 650.2 nm) is shown to proceed at a rate as much as a factor of two greater than that for a non-microcavity equivalent.

  15. All-optical electromagnetically induced transparency using one-dimensional coupled microcavities.

    PubMed

    Naweed, Ahmer; Goldberg, David; Menon, Vinod M

    2014-07-28

    We report the first experimental realization of all-optical electromagnetically induced transparency (EIT) via a pair of coherently interacting SiO2 microcavities in a one-dimensional SiO2/Si3N4 photonic crystal consisting of a distributed Bragg reflector (DBR). The electromagnetic interactions between the coupled microcavities (CMCs), which possess distinct Q-factors, are controlled by varying the number of embedded SiO2/Si3N4 bilayers in the coupling DBR. In case of weak microcavity interactions, the reflectivity spectrum reveals an all-optical EIT resonance which splits into an Autler-Townes-like resonance under condition of strong microcavity coupling. Our results open up the way for implementing optical analogs of quantum coherence in much simpler one-dimensional structures. We also discuss potential applications of CMCs. PMID:25089499

  16. Optical devices and methods employing nanoparticles, microcavities, and semicontinuous metal films

    NASA Technical Reports Server (NTRS)

    Armstrong, Robert L. (Inventor); Shalaev, Vladimir M. (Inventor); Smith, Harold V. (Inventor); Sarychev, Andrey K. (Inventor); Ying, Z. Charles (Inventor)

    2006-01-01

    An optical sensing enhancing material (and corresponding method of making) comprising: a medium, the medium comprising a plurality of aggregated nanoparticles comprising fractals; and a microcavity, wherein the medium is located in a vicinity of the microcavity. Also an optical sensor and sensing method comprising: providing a doped medium, the medium comprising a plurality of aggregated nanoparticles comprising fractals, with the material; locating the doped medium in the vicinity of a microcavity; exciting the doped medium with a light source; and detecting light reflected from the doped medium. Also an optical sensing enhancing material comprising a medium, the medium comprising a semicontinuous metal film of randomly distributed metal particles and their clusters at approximately their percolation threshold. The medium preferably additionally comprises a microcavity/microresonator. Also devices and methods employing such material.

  17. Synchronous characterization of semiconductor microcavity laser beam.

    PubMed

    Wang, T; Lippi, G L

    2015-06-01

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures. PMID:26133832

  18. Synchronous characterization of semiconductor microcavity laser beam

    SciTech Connect

    Wang, T. Lippi, G. L.

    2015-06-15

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam’s tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  19. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  20. Exciton-like electromagnetic excitations in non-ideal microcavity supercrystals

    PubMed Central

    Rumyantsev, Vladimir; Fedorov, Stanislav; Gumennyk, Kostyantyn; Sychanova, Marina; Kavokin, Alexey

    2014-01-01

    We study localized photonic excitations in a quasi-two-dimensional non-ideal binary microcavity lattice with use of the virtual crystal approximation. The effect of point defects (vacancies) on the excitation spectrum is investigated by numerical modelling. We obtain the dispersion and the energy gap of the electromagnetic excitations which may be considered as Frenkel exciton-like quasiparticles and analyze the dependence of their density of states on the defect concentrations in a microcavity supercrystal. PMID:25374150

  1. Optical microcavities based on F2 color centers in lithium fluoride films: modification of spontaneous emission

    NASA Astrophysics Data System (ADS)

    Bonfigli, Francesca; Jacquier, Bernard; Montereali, Rosamaria; Moretti, Paul; Nichelatti, Enrico; Piccinini, M.; Rigneault, Herve; Somma, F.

    2003-04-01

    Lithium fluoride (LiF) films irradiated by low energy electrons were employed as active spacers in all-solid, dielectric optical microcavities emitting in the visible spectral range. We present the results of optical characterization of the spontaneous emission from F2 color centers embedded in a LiF layer confined inside a planar microcavity. These structures seem promising for the realization of novel kinds of solid-state miniaturized emitting devices.

  2. Phase diagram for condensation of microcavity polaritons: From theory to practice

    SciTech Connect

    Marchetti, F. M.; Szymanska, M. H.; Keeling, J. M. J.; Littlewood, P. B.; Kasprzak, J.; Andre, R.; Le Si Dang

    2008-06-15

    The first realization of a polariton condensate was recently achieved in a CdTe microcavity [Kasprzak et al., Nature (London) 443, 409 (2006)]. We compare the experimental phase boundaries, for various detunings and cryostat temperatures, with those found theoretically from a model which accounts for features of microcavity polaritons such as reduced dimensionality, internal composite structure, disorder in the quantum wells, polariton-polariton interactions, and finite lifetime.

  3. Nonlinear optical tuning of photonic crystal microcavities by near-field probe

    SciTech Connect

    Vignolini, Silvia; Zani, Margherita; Riboli, Francesco; Vinattieri, Anna; Wiersma, Diederik S.; Gurioli, Massimo; Intonti, Francesca; Balet, Laurent; Li, Lianhe; Colocci, Marcello; Francardi, Marco; Gerardino, Annamaria; Fiore, Andrea

    2008-07-14

    We report on a nonlinear way to control and tune the dielectric environment of photonic crystal microcavities exploiting the local heating induced by near-field laser excitation at different excitation powers. The temperature gradient due to the optical absorption results in an index of refraction gradient which modifies the dielectric surroundings of the cavity and shifts the optical modes. Reversible tuning can be obtained either by changing the excitation power density or by exciting in different points of the photonic crystal microcavity.

  4. [Toward a high quality glaucoma care].

    PubMed

    Kashiwagi, Kenji

    2012-03-01

    The following studies were performed to solve current problems in glaucoma care and to pursue quality glaucoma care. Using a scanning peripheral anterior chamber depth analyzer that we developed, we: 1) conducted cross-sectional screening for eyes with angle closure; 2) examined longitudinal changes in anterior chamber depth and occurrence rates of primary angle closure in local senior residents; 3) investigated the significance of the anterior chamber and the angle of eyes with open angle glaucoma; and 4) looked into possible applications of anterior chamber depth and the angle in routine examinations. We investigated the effects of retinal glial cells and optic nerve astrocytes on retinal ganglion cell (RGC) survival and neurite growth using a culture system. We also identified candidate genies of retinal glial cells and optic nerve astrocytes affecting RGC survival and neurite growth using microarray and siRNA systems. SRC, a membrane-associated 60-kDa tyrosine kinase, is reported to be involved in neuron death and neurite growth. We developed two types of gene-targeted mice in which we modified the status of SRC phosphorylation. We compared RGC survival and neurite growth by conducting in vivo and in vitro experiments. Adherence is currently a very important issue in the field of glaucoma. We developed a nm thick and composed of 21.5 chitosan-sodium alginate pairs. IOP reduction and its duration, as well as adverse effects, were investigated. In addition, we established and evaluated a support system for glaucoma care in an effort to promote participation of glaucoma patients in glaucoma care using information and communication technology. This system improved the literacy of glaucoma patients as well as glaucoma medical therapy. At the same time, in order to ably provide glaucoma care given the increase in the number of glaucoma patients and the shortage of glaucoma specialists, a tele-medicine system for ophthalmology was developed, in which ophthalmologists

  5. Fabrication of InAs quantum dots in AlAs/GaAs DBR pillar microcavities for single photon sources

    SciTech Connect

    Zhang Bingyang; Solomon, Glenn S.; Pelton, Matthew; Plant, Jocelyn; Santori, Charles; Vuckovic, Jelena; Yamamoto, Yoshihisa

    2005-04-01

    We report the molecular beam epitaxy growth of low-density strain-induced InAs quantum dots (QD) embedded in an AlAs/GaAs distributed Bragg reflector structure for a triggered photon source. By optimal selection of growth temperature, InAs deposited thickness and other experimental parameters, it is possible to grow low density (10/{mu}m{sup 2}) InAs quantum dots with a suitable emission wavelength for a triggered photon source. The empirical formulas for the refractive indices of AlAs and GaAs materials at high temperature over a wide wavelength range are constructed by combining high resolution x-ray diffraction, dynamic optical reflectivity, and optical reflectivity spectrum techniques. Utilizing the electron-beam lithography and electron-cyclotron-resonance plasma etching techniques, a micropost microcavity with the top diameter of 0.6 {mu}m and the post height of 4.2 {mu}m has been fabricated. Narrow, spectrally limited single QD emission embedded in a micropost microcavity is observed in the photoluminescence.

  6. Management of data quality of high level waste characterization

    SciTech Connect

    Winters, W.I., Westinghouse Hanford

    1996-06-12

    Over the past 10 years, the Hanford Site has been transitioning from nuclear materials production to Site cleanup operations. High-level waste characterization at the Hanford Site provides data to support present waste processing operations, tank safety programs, and future waste disposal programs. Quality elements in the high-level waste characterization program will be presented by following a sample through the data quality objective, sampling, laboratory analysis and data review process. Transition from production to cleanup has resulted in changes in quality systems and program; the changes, as well as other issues in these quality programs, will be described. Laboratory assessment through quality control and performance evaluation programs will be described, and data assessments in the laboratory and final reporting in the tank characterization reports will be discussed.

  7. Simple and rapid CD4 testing based on large-field imaging system composed of microcavity array and two-dimensional photosensor.

    PubMed

    Saeki, Tatsuya; Sugamura, Yuriko; Hosokawa, Masahito; Yoshino, Tomoko; Lim, Tae-Kyu; Harada, Manabu; Matsunaga, Tadashi; Tanaka, Tsuyoshi

    2015-05-15

    This study presents a novel method for CD4 testing based on one-shot large-field imaging. The large-field imaging system was fabricated by a microcavity array and a two-dimensional (2D) photosensor within the desk-top-sized instrument. The microcavity array was employed to separate leukocytes from whole blood based on differences in the size of leukocytes and other blood cells. The large-field imaging system with lower side irradiation enabled acquisition of cell signatures with high signal-to-noise ratio, because the metallic substrate of the microcavity array obstructed excessive excitation light. In this setting, dual-color imaging of CD4(+) and CD8(+) T cells was achieved within the entire image area (64 mm(2)) in 2s. The practical performance of the large-field imaging system was demonstrated by determining the CD4/CD8 ratio in a few microliter of control whole blood as small as those obtained by a finger prick. The CD4/CD8 ratios measured using the large-field imaging system correlated well with those measured by microscopic analysis. These results indicate that our proposed system provides a simple and rapid CD4 testing for the application of HIV/AIDS treatment. PMID:25192872

  8. A parametric study on the PD pulses activity within micro-cavities

    NASA Astrophysics Data System (ADS)

    Ganjovi, Alireza A.

    2016-03-01

    A two-dimensional kinetic model has been used to parametric investigation of the spark-type partial discharge pulses inside the micro-cavities. The model is based on particle-in-cell methods with Monte Carlo Collision techniques for modeling of collisions. Secondary processes like photo-emission and cathode-emission are considered. The micro-cavity may be sandwiched between two metallic conductors or two dielectrics. The discharge within the micro-cavity is studied in conjunction with the external circuit. The model is used to successfully simulate the evolution of the discharge and yield useful information about the build-up of space charge within the micro-cavity and the consequent modification of the applied electric field. The phase-space scatter plots for electrons, positive, and negative ions are obtained in order to understand the manner in which discharge progresses over time. The rise-time and the magnitude of the discharge current pulse are obtained and are seen to be affected by micro-cavity dimensions, gas pressure within the micro-cavity, and the permittivity of surrounding dielectrics. The results have been compared with existing experimental, theoretical, and computational results, wherever possible. An attempt has been made to understand the nature of the variations in terms of the physical processes involved.

  9. Delivering High-Quality Cancer Care: The Critical Role of Quality Measurement

    PubMed Central

    Spinks, Tracy; Ganz, Patricia A.; Sledge, George W.; Levit, Laura; Hayman, James A.; Eberlein, Timothy J.; Feeley, Thomas W.

    2014-01-01

    In 1999, the Institute of Medicine (IOM) published Ensuring Quality Cancer Care, an influential report that described an ideal cancer care system and issued ten recommendations to address pervasive gaps in the understanding and delivery of quality cancer care. Despite generating much fervor, the report’s recommendations—including two recommendations related to quality measurement—remain largely unfulfilled. Amidst continuing concerns regarding increasing costs and questionable quality of care, the IOM charged a new committee with revisiting the 1999 report and with reassessing national cancer care, with a focus on the aging US population. The committee identified high-quality patient-clinician relationships and interactions as central drivers of quality and attributed existing quality gaps, in part, to the nation’s inability to measure and improve cancer care delivery in a systematic way. In 2013, the committee published its findings in Delivering High-Quality Cancer Care: Charting a New Course for a System in Crisis, which included two recommendations that emphasize coordinated, patient-centered quality measurement and information technology enhancements: Develop a national quality reporting program for cancer care as part of a learning health care system; and,Develop an ethically sound learning health care information technology system for cancer that enables real-time analysis of data from cancer patients in a variety of care settings. These recommendations underscore the need for independent national oversight, public-private collaboration, and substantial funding to create robust, patient-centered quality measurement and learning enterprises to improve the quality, accessibility, and affordability of cancer care in America. PMID:24839592

  10. Light harvesting by a spherical silicon microcavity

    NASA Astrophysics Data System (ADS)

    Garín, M.; Fenollosa, R.; Ortega, P.; Meseguer, F.

    2016-01-01

    Silicon colloids are presented as efficient absorbers in the VIS-NIR region. The theory of resonant absorption by Mie modes in a single high-index sphere is reviewed and engineering rules established. The presented model predicts enhanced absorption in the crystalline silicon band-to-band absorption region, with absorption efficiencies exceeding one in the VIS and excellent NIR response. A maximum resonant absorption efficiency close to 4 can be obtained at the violet region (425 nm), and values above 0.25 are possible in the bandgap edge at wavelengths up to 1400 nm. Silicon colloids are proposed as a promising cost-effective, silicon saving, sunlight harvesters with improved VIS and NIR response.

  11. Significant photoinduced Kerr rotation achieved in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Cherbunin, R. V.; Vladimirova, M.; Kavokin, K. V.; Mikhailov, A. V.; Kopteva, N. E.; Lagoudakis, P. G.; Kavokin, A. V.

    2015-05-01

    Giant Kerr rotation and ellipticity are observed and investigated in an asymmetric planar microcavity with a quantum well in the active region. Rotation angle of the polarization plane as well as ellipticity were determined from time- and frequency-resolved measurements of the Stokes vector components of reflected light. It was found that in a small range of the cavity mode detunings the polarized pump pulse creates a large splitting of the lower polariton branch while leaving its linewidth almost the same. This fact gives a possibility to observe at such detunings the Kerr rotation angle and ellipticity, close to their extremes. A theoretical analysis shows that the decisive role in reaching extreme polarization rotation angles is played by the structure asymmetry. Comprehensive analysis of the polarization state of the light in this regime shows that both renormalization of the exciton energy and the saturation of the excitonic resonance contribute to the observed optical nonlinearities.

  12. Progress in Atom Chips and the Integration of Optical Microcavities

    NASA Astrophysics Data System (ADS)

    Hinds, E. A.; Trupke, M.; Darquie, B.; Goldwin, J.; Dutier, G.

    2008-04-01

    We review recent progress at the Centre for Cold Matter in developing atom chips. An important advantage of miniaturizing atom traps on a chip is the possibility of obtaining very tight trapping structures with the capability of manipulating atoms on the micron length scale. We recall some of the pros and cons of bringing atoms close to the chip surface, as is required in order to make small static structures, and we discuss the relative merits of metallic, dielectric and superconducting chip surfaces. We point out that the addition of integrated optical devices on the chip can enhance its capability through single atom detection and controlled photon production. Finally, we review the status of integrated microcavities that have recently been demonstrated at our Centre and discuss their prospects for future development.

  13. Coherent coupling of molecular resonators with a microcavity mode

    PubMed Central

    Shalabney, A.; George, J.; Hutchison, J.; Pupillo, G.; Genet, C.; Ebbesen, T. W.

    2015-01-01

    The optical hybridization of the electronic states in strongly coupled molecule–cavity systems have revealed unique properties, such as lasing, room temperature polariton condensation and the modification of excited electronic landscapes involved in molecular isomerization. Here we show that molecular vibrational modes of the electronic ground state can also be coherently coupled with a microcavity mode at room temperature, given the low vibrational thermal occupation factors associated with molecular vibrations, and the collective coupling of a large ensemble of molecules immersed within the cavity-mode volume. This enables the enhancement of the collective Rabi-exchange rate with respect to the single-oscillator coupling strength. The possibility of inducing large shifts in the vibrational frequency of selected molecular bonds should have immediate consequences for chemistry. PMID:25583259

  14. PT symmetry breaking and nonlinear optical isolation in coupled microcavities

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Chong, Y. D.

    2016-04-01

    We perform a theoretical study of nonlinear optical isolator devices based on coupled microcavities with gain and loss. Using coupled-mode theory, we derive a correspondence between the boundary of asymptotic stability in the nonlinear regime, where gain saturation is present, and the PT-breaking transition in the underlying linear system. For zero detuning and weak input intensity, the onset of optical isolation can be rigorously derived, and corresponds precisely to the PT transition point. When the couplings to the external ports are unequal, the isolation ratio exhibits an abrupt jump at the transition point, determined by the ratio of the couplings. This could be exploited to realize an actively controlled nonlinear optical isolator, in which strong optical isolation can be switched on or off using tiny variations in the inter-resonator separation.

  15. Hybrid polaritons in a resonant inorganic/organic semiconductor microcavity

    SciTech Connect

    Höfner, M. Sadofev, S.; Henneberger, F.; Kobin, B.; Hecht, S.

    2015-11-02

    We demonstrated the strong coupling regime in a hybrid inorganic-organic microcavity consisting of (Zn,Mg)O quantum wells and ladder-type oligo(p-phenylene) molecules embedded in a polymer matrix. A Fabry-Pérot cavity is formed by an epitaxially grown lower ZnMgO Bragg reflector and a dielectric mirror deposited atop of the organic layer. A clear anticrossing behavior of the polariton branches related to the Wannier-Mott and Frenkel excitons, and the cavity photon mode with a Rabi-splitting reaching 50 meV, is clearly identified by angular-dependent reflectivity measurements at low temperature. By tailoring the structural design, an equal mixing with weights of about 0.3 for all three resonances is achieved for the middle polariton branch at an incidence angle of about 35°.

  16. Nonequilibrium and nonlinear defect states in microcavity-polariton condensates

    NASA Astrophysics Data System (ADS)

    Chen, Ting-Wei; Jheng, Shih-Da; Hsieh, Wen-Feng; Cheng, Szu-Cheng

    2016-05-01

    The nonequilibrium and nonlinear defect modes (NNDMs), localized by a defect in a nonequilibrium microcavity-polariton condensate (MPC), are studied. There are three analytic solutions of NNDMs in a point defect: the bright NNDM, a bound state with two dark solitons for an attractive potential, and a gray soliton bound by a defect for a repulsive potential. We find that the stable NNDMs in a nonequilibrium MPC are the bright NNDM and gray soliton bound by a defect. The bright NNDM, which has the hyperbolic cotangent form, is a bright localized state existing in a uniform MPC. The bright NNDM is a unique state occurring in a nonequilibrium MPC that has pump-dissipation and repulsive-nonlinearity characters. No such state can exist in an equilibrium system with repulsive nonlinearity.

  17. Energy shell structure in a dielectric elliptic microcavity.

    PubMed

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Ji-Hwan; Kim, Chil-Min

    2016-01-01

    An energy shell structure depending on eccentricity is analyzed in a dielectric elliptic microcavity. Through the analysis, it is explicated that the energy shell structure is governed by classical constant actions of periodic orbits. For clarification, the relation between dominances of the periodic orbits and bifurcation behaviors are obtained and the length spectra based on eigenvalues computed by a numerical method are compared with the exact lengths of the periodic orbits obtained by analytic calculations. By matching effective wave numbers obtained from the periodic orbit lengths to exact wave numbers of stationary states in closed and open cavities, we find deviations provoked from the openness. We show that these deviations are caused by additional phase factors in the Einstein-Brillouin-Keller quantization. PMID:26871069

  18. Optical characterization of porous silicon microcavities for glucose oxidase biosensing

    NASA Astrophysics Data System (ADS)

    Palestino, G.; Agarwal, V.; Garcia, D. B.; Legros, R.; Pérez, E.; Gergely, C.

    2008-04-01

    PSi microcavity (PSiMc) is characterized by a narrow resonance peak in the optical spectrum that is very sensitive to small changes in the refractive index. We report that the resonant optical cavities of PSi structures can be used to enhance the detection of labeled fluorescent biomolecules. Various PSi configurations were tested in order to compare the optical response of the PSi devices to the capture of organic molecules. Morphological and topographical analyses were performed on PSiMc using Atomic Force (AFM) and Scanning Electron (SEM) microscopies. The heterogeneity in pores lengths resulting from etching process assures a better penetration of larger molecules into the pores and sensor sensitivity depends on the pore size. Molecular detection is monitored by the successive red shifts in the reflectance spectra after the stabilization of PSiMc with 3-aminopropyltriethoxysilane (APTES). The glucose oxidase was cross linked into the PSiMc structures following a silane-glutaraldehyde (GTA) chemistry.

  19. Two-atom spontaneous emission in a planar microcavity

    SciTech Connect

    Ujihara, Kikuo; Dung, Ho Trung

    2002-11-01

    Spontaneous emission in a planar microcavity by two identical and spatially separated two-level atoms, both of them initially excited, is considered under fourth-order perturbation approximation in atom-field coupling constants. A delay-differential equation with proper retardation times for the probability of both atoms in the upper state is derived and expressions for the emitted-light intensity and spectrum are given. It is numerically shown that, while two-atom cooperation is enhanced for small interatomic distances, the two-atom vacuum Rabi oscillation is somewhat suppressed compared to the single-atom oscillation level when the interatomic separation is close to the cavity transverse coherence length.

  20. Energy shell structure in a dielectric elliptic microcavity

    NASA Astrophysics Data System (ADS)

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Ji-Hwan; Kim, Chil-Min

    2016-01-01

    An energy shell structure depending on eccentricity is analyzed in a dielectric elliptic microcavity. Through the analysis, it is explicated that the energy shell structure is governed by classical constant actions of periodic orbits. For clarification, the relation between dominances of the periodic orbits and bifurcation behaviors are obtained and the length spectra based on eigenvalues computed by a numerical method are compared with the exact lengths of the periodic orbits obtained by analytic calculations. By matching effective wave numbers obtained from the periodic orbit lengths to exact wave numbers of stationary states in closed and open cavities, we find deviations provoked from the openness. We show that these deviations are caused by additional phase factors in the Einstein-Brillouin-Keller quantization.

  1. Strong exciton-photon coupling in open semiconductor microcavities

    SciTech Connect

    Dufferwiel, S.; Fras, F.; Walker, P. M.; Li, F.; Giriunas, L.; Makhonin, M. N.; Wilson, L. R.; Skolnick, M. S.; Krizhanovskii, D. N.; Trichet, A.; Smith, J. M.; Clarke, E.

    2014-05-12

    We present a method to implement 3-dimensional polariton confinement with in-situ spectral tuning of the cavity mode. Our tunable microcavity is a hybrid system consisting of a bottom semiconductor distributed Bragg reflector (DBR) with a cavity containing quantum wells (QWs) grown on top and a dielectric concave DBR separated by a micrometer sized gap. Nanopositioners allow independent positioning of the two mirrors and the cavity mode energy can be tuned by controlling the distance between them. When close to resonance, we observe a characteristic anticrossing between the cavity modes and the QW exciton demonstrating strong coupling. For the smallest radii of curvature concave mirrors of 5.6 μm and 7.5 μm, real-space polariton imaging reveals submicron polariton confinement due to the hemispherical cavity geometry.

  2. Hybrid polaritons in a resonant inorganic/organic semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Höfner, M.; Sadofev, S.; Kobin, B.; Hecht, S.; Henneberger, F.

    2015-11-01

    We demonstrated the strong coupling regime in a hybrid inorganic-organic microcavity consisting of (Zn,Mg)O quantum wells and ladder-type oligo(p-phenylene) molecules embedded in a polymer matrix. A Fabry-Pérot cavity is formed by an epitaxially grown lower ZnMgO Bragg reflector and a dielectric mirror deposited atop of the organic layer. A clear anticrossing behavior of the polariton branches related to the Wannier-Mott and Frenkel excitons, and the cavity photon mode with a Rabi-splitting reaching 50 meV, is clearly identified by angular-dependent reflectivity measurements at low temperature. By tailoring the structural design, an equal mixing with weights of about 0.3 for all three resonances is achieved for the middle polariton branch at an incidence angle of about 35°.

  3. Spatial Patterns of Dissipative Polariton Solitons in Semiconductor Microcavities.

    PubMed

    Chana, J K; Sich, M; Fras, F; Gorbach, A V; Skryabin, D V; Cancellieri, E; Cerda-Méndez, E A; Biermann, K; Hey, R; Santos, P V; Skolnick, M S; Krizhanovskii, D N

    2015-12-18

    We report propagating bound microcavity polariton soliton arrays consisting of multipeak structures either along (x) or perpendicular (y) to the direction of propagation. Soliton arrays of up to five solitons are observed, with the number of solitons controlled by the size and power of the triggering laser pulse. The breakup along the x direction occurs when the effective area of the trigger pulse exceeds the characteristic soliton size determined by polariton-polariton interactions. Narrowing of soliton emission in energy-momentum space indicates phase locking between adjacent solitons, consistent with numerical modeling which predicts stable multihump soliton solutions. In the y direction, the breakup originates from inhomogeneity across the wave front in the transverse direction which develops into a stable array only in the solitonic regime via phase-dependent interactions of propagating fronts. PMID:26722931

  4. Field emission and lifetime of microcavity plasma

    SciTech Connect

    Kim, G. J.; Lee, J. K.; Iza, F.

    2009-01-15

    Microplasmas with cylindrical hollow cathode have been studied by means of two-dimensional particle-in-cell/Monte-Carlo collision (PIC/MCC) simulations. For a given input power, the onset of field emission from the cathode surface caused by the strong electric field generated in these discharges leads to a reduction of the discharge voltage and an increase in plasma density. The plasma density profile can be strongly influenced by localized enhancements of the electric field, which in turn will affect the erosion profile of the cathode. The cathode erosion profile is predicted in this work by combining the ion kinetic information obtained from the PIC/MCC simulation with the sputtering yield computed using SRIM [J. F. Ziegler, J. P. Biersack, and M. D. Ziegler, SRIM: The Stopping and Range of Ions in Matter (Lulu, Chester, 2008)]. The entrance of the cathode and the center region are the areas most susceptible to ion-induced damage. The lifetime of the device, however, can be extended by operating the device at high pressure and by reducing the operating voltage by means of field emission and/or additional electron emitting processes from the cathode.

  5. High quality factor, fully switchable terahertz superconducting metasurface

    SciTech Connect

    Scalari, G. Maissen, C.; Faist, J.; Cibella, S.; Leoni, R.

    2014-12-29

    We present a complementary THz metasurface realised with Niobium thin film which displays a quality factor Q = 54 and a fully switchable behaviour as a function of the temperature. The switching behaviour and the high quality factor are due to a careful design of the metasurface aimed at maximising the ohmic losses when the Nb is above the critical temperature and minimising the radiative coupling. The superconductor allows the operation of the cavity with high Q and the use of inductive elements with a high aspect ratio. Comparison with three dimensional finite element simulations highlights the crucial role of the inductive elements and of the kinetic inductance of the Cooper pairs in achieving the high quality factor and the high field enhancement.

  6. Concrete Waste Recycling Process for High Quality Aggregate

    SciTech Connect

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-15

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  7. Realization of high quality production schedules: Structuring quality factors via iteration of user specification processes

    NASA Technical Reports Server (NTRS)

    Hamazaki, Takashi

    1992-01-01

    This paper describes an architecture for realizing high quality production schedules. Although quality is one of the most important aspects of production scheduling, it is difficult, even for a user, to specify precisely. However, it is also true that the decision as to whether a scheduler is good or bad can only be made by the user. This paper proposes the following: (1) the quality of a schedule can be represented in the form of quality factors, i.e. constraints and objectives of the domain, and their structure; (2) quality factors and their structure can be used for decision making at local decision points during the scheduling process; and (3) that they can be defined via iteration of user specification processes.

  8. Estimation of Purcell factor from mode-splitting spectra in an optical microcavity

    SciTech Connect

    Oezdemir, Sahin Kaya; Zhu Jiangang; He, Lina; Yang, Lan

    2011-03-15

    We investigate scattering process in an ultrahigh-Q optical microcavity coupled to subwavelength scatterers by introducing splitting quality Q{sub sp}, a dimensionless parameter defined as the ratio of the scatterer-induced mode splitting to the total loss of the coupled system. A simple relation is introduced to directly estimate the Purcell factor from single-shot measurement of transmission spectrum of scatterer-coupled cavity. Experiments with polystyrene (PS) and gold (Au) nanoparticles, erbium ions, and Influenza A virions show that Purcell-factor-enhanced preferential funneling of scattering into the cavity mode takes place regardless of the scatterer type. Experimentally determined highest Q{sub sp} for single PS and Au nanoparticles are 9.4 and 16.19 corresponding to Purcell factors with lower bounds of 353 and 1049, respectively. The highest observed Q{sub sp} was 31.2 for an ensemble of Au particles. These values are the highest Q{sub sp} and Purcell factors reported up to date.

  9. Quality of life and the high-dependency unit.

    PubMed

    Brooks, N

    2000-02-01

    This study was designed to identify and measure the patients' perspective of the concept quality of life within the context of a high-dependency unit (HDU). Data were collected in two phases. In phase one, 55 patients were interviewed, which resulted in the concept clarification of quality of life as: physical, social, psychological and family/friends. In phase two, 51 patients undertook quality-of-life assessment using validated instruments the Quality of Life Index (Ferrans & Powers 1985) and the Global Quality of Life Scale (Hyland & Sodergren 1997). Post-HDU patients demonstrated improvements upon pre-admission scores in both instruments (the social domain in the quality of life index being the exception), although this only reached statistical significance P<0.05 in the overall index score and within the domains of health and family. When exploring variables of age and severity of illness (Apache 2 score, Knaus et al. 1980) it was the people who were older and physiologically compromised to an increased extent (P<0.05) who demonstrated higher levels of satisfaction with their resulting quality of life. This study has been successful in providing patients with an opportunity to participate more actively in service evaluation and has identified the need for future evaluation of HDUs to move beyond physiological measures, to incorporate the impact that illness leading to admission to an HDU has upon the patients' ability to function and their resulting quality of life. PMID:10790712

  10. High-Q CMOS-integrated photonic crystal microcavity devices

    PubMed Central

    Mehta, Karan K.; Orcutt, Jason S.; Tehar-Zahav, Ofer; Sternberg, Zvi; Bafrali, Reha; Meade, Roy; Ram, Rajeev J.

    2014-01-01

    Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies. Although photonic crystal (PhC) microresonators can be advantageous to the more commonly used microring devices due to the former's low mode volumes, fabrication of PhC cavities has typically relied on electron-beam lithography, which precludes integration with large-scale and reproducible CMOS fabrication. Here, we demonstrate wavelength-scale polycrystalline silicon (pSi) PhC microresonators with Qs up to 60,000 fabricated within a bulk CMOS process. Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300–9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V. This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems. PMID:24518161

  11. Developing Visions of High-Quality Mathematics Instruction

    ERIC Educational Resources Information Center

    Munter, Charles

    2014-01-01

    This article introduces an interview-based instrument that was created for the purposes of characterizing the visions of high-quality mathematics instruction of teachers, principals, mathematics coaches, and district leaders and tracking changes in those visions over time. The instrument models trajectories of perceptions of high-quality…

  12. Effective multidisciplinary working: the key to high-quality care.

    PubMed

    Ndoro, Samuel

    This article explores multidisciplinary team working, inter-disciplinary, trans-disciplinary and effective collaborative practice in order to provide high-quality patient care. It discusses different views on collaboration, some of the issues around cross-discipline and multi-agency working and concerns around promoting 'high-quality' care. It also discusses the importance of evidence-based practice in multidisciplinary teams. Issues around good-quality care, clinical governance and the audit cycle in MDTs are addressed. The article highlights the importance of the 6Cs (care, compassion, competence, communication, courage and commitment) in MDTs if quality care is to be achieved. The article also explores advantages and limitations of multidisciplinary team working, trans-disciplinary working and inter-professional working in developing and delivering high-quality patient-centred care. Further research is needed on how clinical audits can help to improve how MDTs function in order improve the quality of service provided to clients. PMID:25072333

  13. Silicon photonic crystal microarrays for high throughput label-free detection of lung cancer cell line lysates with sensitivity and specificity

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Gemmill, Robert M.; Chen, Ray T.

    2013-03-01

    Detection of biomolecules on microarrays based on label-free on-chip optical biosensors is very attractive since this format avoids complex chemistries caused by steric hindrance of labels. Application areas include the detection of cancers and allergens, and food-borne pathogens to name a few. We have demonstrated photonic crystal microcavity biosensors with high sensitivity down to 1pM concentrations (67pg/ml). High sensitivities were achieved by slow light engineering which reduced the radiation loss and increased the stored energy in the photonic crystal microcavity resonance mode. Resonances with high quality factor Q~26,760 in liquid ambient, coupled with larger optical mode volumes allowed enhanced interaction with the analyte biomolecules which resulted in sensitivities down to 10 cells per micro-liter to lung cancer cell lysates. The specificity of detection was ensured by multiplexed detections from multiple photonic crystal microcavities arrayed on the arms of a multimode interference power splitter. Specific binding interactions and control experiments were performed simultaneously at the same instant of time with the same 60 microliter sample volume. Specificity is further ensured by sandwich assay methods in the multiplexed experiment. Sandwich assay based amplification increased the sensitivity further resulting in the detection of lung cancer cell lysates down to concentrations of 2 cells per micro-liter. The miniaturization enabled by photonic crystal biosensors coupled with waveguide interconnected layout thus offers the potential of high throughput proteomics with high sensitivity and specificity.

  14. Physical analysis of the response properties of porous silicon microcavity biosensor

    NASA Astrophysics Data System (ADS)

    Wu, Chao; Rong, Guoguang; Xu, Junteng; Pan, Shengfei; Zhu, Yongxin

    2012-04-01

    Porous silicon possesses great potential in developing label-free biosensors of high sensitivity. In this work, a well-tuned resonant structure or microcavity is fabricated, and based on it, an intensity-interrogated sensing technique is thoroughly investigated. Using glucose as a target, this method is demonstrated to be advantageous in lowering detection limit while achieving high reliability. In this experiment the limit is extended from approximately 7×10-4RIU to 7×10-5RIU, compared with the redshift method. We also elaborate the physical mechanisms in the sensing process, which give rise to the aberration of reflectivity variation when different procedures (i.e. dynamic vs. static) are executed. It is postulated to be caused by concentration profile change in diffusion boundary layer in response to flow rate difference. We also find that the response time keeps a steady low value before ramping up in extremely low concentration sensing schemes. We arbitrarily cut the response time vs. concentration curve into two regimes, which are dominated by relatively high adsorption rate and slow mass diffusion. In the last part, tailing effect is investigated and eliminated by increasing flow rate. The theory will be instructive in achieving optimum results in operations where physisorption in the porous material plays an important role.

  15. Can patients reliably identify safe, high quality care?

    PubMed Central

    Tevis, Sarah E.; Schmocker, Ryan K.; Kennedy, Gregory D.

    2015-01-01

    The Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey is a publicly reported tool that measures patient satisfaction. As both patients and Centers for Medicare & Medicaid Services (CMS) reimbursement rely on survey results as a metric of quality of care, we reviewed the current literature to determine if patient satisfaction correlates with quality, safety, or patient outcomes. We found varying associations between safety culture, process of care measure compliance, and patient outcomes with patient satisfaction on the HCAHPS survey. Some studies found inverse relationships between quality and safety metrics and patient satisfaction. The measure that most reliably correlated with high patient satisfaction was low readmission rate. Future studies using patient specific data are needed to better identify which factors most influence patient satisfaction and to determine if patient satisfaction is a marker of safer and better quality care. Furthermore, the HCAHPS survey should continue to undergo evaluations to assure it generates predictable results. PMID:26413179

  16. Providing high-quality care in primary care settings

    PubMed Central

    Beaulieu, Marie-Dominique; Geneau, Robert; Grande, Claudio Del; Denis, Jean-Louis; Hudon, Éveline; Haggerty, Jeannie L.; Bonin, Lucie; Duplain, Réjean; Goudreau, Johanne; Hogg, William

    2014-01-01

    Abstract Objective To gain a deeper understanding of how primary care (PC) practices belonging to different models manage resources to provide high-quality care. Design Multiple-case study embedded in a cross-sectional study of a random sample of 37 practices. Setting Three regions of Quebec. Participants Health care professionals and staff of 5 PC practices. Methods Five cases showing above-average results on quality-of-care indicators were purposefully selected to contrast on region, practice size, and PC model. Data were collected using an organizational questionnaire; the Team Climate Inventory, which was completed by health care professionals and staff; and 33 individual interviews. Detailed case histories were written and thematic analysis was performed. Main findings The core common feature of these practices was their ongoing effort to make trade-offs to deliver services that met their vision of high-quality care. These compromises involved the same 3 areas, but to varying degrees depending on clinic characteristics: developing a shared vision of high-quality care; aligning resource use with that vision; and balancing professional aspirations and population needs. The leadership of the physician lead was crucial. The external environment was perceived as a source of pressure and dilemmas rather than as a source of support in these matters. Conclusion Irrespective of their models, PC practices’ pursuit of high-quality care is based on a vision in which accessibility is a key component, balanced by appropriate management of available resources and of external environment expectations. Current PC reforms often create tensions rather than support PC practices in their pursuit of high-quality care. PMID:24829023

  17. Development of L-lactate dehydrogenase biosensor based on porous silicon resonant microcavities as fluorescence enhancers.

    PubMed

    Jenie, S N Aisyiyah; Prieto-Simon, Beatriz; Voelcker, Nicolas H

    2015-12-15

    The up-regulation of L-lactate dehydrogenase (LDH), an intracellular enzyme present in most of all body tissues, is indicative of several pathological conditions and cellular death. Herein, we demonstrate LDH detection using porous silicon (pSi) microcavities as a luminescence-enhancing optical biosensing platform. Non-fluorescent resazurin was covalently attached onto the pSi surface via thermal hydrocarbonisation, thermal hydrosylilation and acylation. Each surface modification step was confirmed by means of FTIR and the optical shifts of the resonance wavelength of the microcavity. Thermal hydrocarbonisation also afforded excellent surface stability, ensuring that the resazurin was not reduced on the pSi surface. Using a pSi microcavity biosensor, the fluorescence signal upon detection of LDH was amplified by 10 and 5-fold compared to that of a single layer and a detuned microcavity, respectively, giving a limit of detection of 0.08 U/ml. The biosensor showed a linear response between 0.16 and 6.5 U/ml, covering the concentration range of LDH in normal as well as damaged tissues. The biosensor was selective for LDH and did not produce a signal upon incubation with another NAD-dependant enzyme L-glutamic dehydrogenase. The use of the pSi microcavity as a sensing platform reduced reagent usage by 30% and analysis time threefold compared to the standard LDH assay in solution. PMID:26201980

  18. High flux and high quality FEL resonator mirrors

    SciTech Connect

    Anthony, F.M.; Mistretta, A.L.; Tonnessen, T.W. )

    1989-08-01

    The Free Electron Laser Cooled Mirror Technology Development Program was highly successful; this technology can be applied to cooled silicon mirror requirements for RF linac FEL's. Designs were developed for a 100 cm hyperboloid subjected to a peak absorbed flux of 1000 w/cm[sup 2] and for a 50 cm paraboloid with an absorbed peak flux of 500 w/cm[sup 2]. Although the design concepts were essentially the same detailed implementation was somewhat different for each of the mirrors. Both designs incorporated variable geometry and internal flow tailoring over the planform area so as to produce a near spherical distortion response to the input Gaussian power distribution. This enhanced correctability of the overall distortion such that the net distortion was only 0.2 A/(w/cm[sup 2]) after correction for sphere, piston and bit as compared to a design goal of 0.5 A/(w/cm[sup 2]). Structural integrity testing of small samples, that incorporated internal geometries of both types of mirrors, verified the adequacy of the designs. Fabrication of the different types of test specimens demonstrated the producibility of the configurations. Planform bonding of manifold simulations was successful; they type of bonding is required to produce a 50 cm diameter circular silicon mirror from boules that are somewhat smaller in diameter. After planform bonding of preforms they were machined, etched, assembled into pressure test specimens, and burst pressure tested. The average burst pressure of 1550 psig was somewhat stronger than early SHOP specimens of the same configuration but somewhat lower than more recently produced specimens which evidenced burst pressure strengths of 2500 psig. Demonstrated planform bond strengths are more than adequate for the mirrors of interest, better performance can be expected as the bonding precess is refined. These, and the other experimental results indicate the large factor of safety provided by the designs.

  19. High flux and high quality FEL resonator mirrors. Final report

    SciTech Connect

    Anthony, F.M.; Mistretta, A.L.; Tonnessen, T.W.

    1989-08-01

    The Free Electron Laser Cooled Mirror Technology Development Program was highly successful; this technology can be applied to cooled silicon mirror requirements for RF linac FEL`s. Designs were developed for a 100 cm hyperboloid subjected to a peak absorbed flux of 1000 w/cm{sup 2} and for a 50 cm paraboloid with an absorbed peak flux of 500 w/cm{sup 2}. Although the design concepts were essentially the same detailed implementation was somewhat different for each of the mirrors. Both designs incorporated variable geometry and internal flow tailoring over the planform area so as to produce a near spherical distortion response to the input Gaussian power distribution. This enhanced correctability of the overall distortion such that the net distortion was only 0.2 A/(w/cm{sup 2}) after correction for sphere, piston and bit as compared to a design goal of 0.5 A/(w/cm{sup 2}). Structural integrity testing of small samples, that incorporated internal geometries of both types of mirrors, verified the adequacy of the designs. Fabrication of the different types of test specimens demonstrated the producibility of the configurations. Planform bonding of manifold simulations was successful; they type of bonding is required to produce a 50 cm diameter circular silicon mirror from boules that are somewhat smaller in diameter. After planform bonding of preforms they were machined, etched, assembled into pressure test specimens, and burst pressure tested. The average burst pressure of 1550 psig was somewhat stronger than early SHOP specimens of the same configuration but somewhat lower than more recently produced specimens which evidenced burst pressure strengths of 2500 psig. Demonstrated planform bond strengths are more than adequate for the mirrors of interest, better performance can be expected as the bonding precess is refined. These, and the other experimental results indicate the large factor of safety provided by the designs.

  20. High Quality Preschool Programs: What Would Vygotsky Say?

    ERIC Educational Resources Information Center

    Bodrova, Elena; Leong, Deborah J.

    2005-01-01

    The paper considers the definition of high quality preschool from a Vygotskian perspective. Similarities and differences in the issues faced in Russia and those in the United States are discussed as background. Three major ideas are considered from the work of Vygotsky and of his students/colleagues, Daniel Elkonin and Alexander Zaporozhets. The…

  1. The impact of high speed roller ginning on yarn quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent advance in cotton ginning technology have resulted in increases in the speed, throughput, and overall economics of roller ginning to make it competitive with conventional saw ginning. The present study was aimed at determining if the improvements in fiber quality, i.e. longer fibers with high...

  2. Attracting and Retaining High-Quality Professionals in Science Education.

    ERIC Educational Resources Information Center

    Weld, Jeffrey

    1998-01-01

    To attract and retain high-quality teachers, the education system must address science teachers' sense of professional isolation, administrators' lack of receptivity to thoughtful teachers' ideas, egalitarian salary compensation schemes, and lack of professional recognition. An outstanding chemistry teacher-turned-pharmaceutical saleswoman is…

  3. Novel, high-quality surface plasmon resonance microscopy

    PubMed Central

    Thariani, Rahber; Yager, Paul

    2016-01-01

    A surface plasmon resonance microscope capable of high-quality speckle-free imaging has been designed that uses a laser as a source. An inexpensive acoustic transducer is used to reduce speckle and other image artifacts arising from the use of illumination from an inexpensive laser pointer. The microscope is described and operation of the system demonstrated.

  4. Improved electrode gives high-quality biological recordings

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Lippitt, M. W.

    1964-01-01

    To obtain high quality waveforms from a subject engaged in physical activity, an improved electrode assembly has been devised. This consists of a cup containing an electrically conductive paste and a silver electrode. The paste maintains contact between the skin and the plate.

  5. Child Care: Use of Standards To Ensure High Quality Care.

    ERIC Educational Resources Information Center

    General Accounting Office, Washington, DC. Health, Education, and Human Services Div.

    Prepared to assist Congress in its deliberations of various child care proposals, this report identifies key child care center standards that are critical in helping to ensure high quality child care. The article also examines the extent to which states incorporate these standards into their own standards, and discusses other important issues that…

  6. High-quality Health Information Provision for Stroke Patients

    PubMed Central

    Du, Hong-Sheng; Ma, Jing-Jian; Li, Mu

    2016-01-01

    Objective: High-quality information provision can allow stroke patients to effectively participate in healthcare decision-making, better manage the stroke, and make a good recovery. In this study, we reviewed information needs of stroke patients, methods for providing information to patients, and considerations needed by the information providers. Data Sources: The literature concerning or including information provision for patients with stroke in English was collected from PubMed published from 1990 to 2015. Study Selection: We included all the relevant articles on information provision for stroke patients in English, with no limitation of study design. Results: Stroke is a major public health concern worldwide. High-quality and effective health information provision plays an essential role in helping patients to actively take part in decision-making and healthcare, and empowering them to effectively self-manage their long-standing chronic conditions. Different methods for providing information to patients have their relative merits and suitability, and as a result, the effective strategies taken by health professionals may include providing high-quality information, meeting patients’ individual needs, using suitable methods in providing information, and maintaining active involvement of patients. Conclusions: It is suggested that to enable stroke patients to access high-quality health information, greater efforts need to be made to ensure patients to receive accurate and current evidence-based information which meets their individual needs. Health professionals should use suitable information delivery methods, and actively involve stroke patients in information provision. PMID:27569241

  7. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities

    PubMed Central

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-01

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low. PMID:25518899

  8. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities.

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-01

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low. PMID:25518899

  9. Method for producing high quality thin layer films on substrates

    DOEpatents

    Strongin, M.; Ruckman, M.; Strongin, D.

    1994-04-26

    A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate. 4 figures.

  10. Method for producing high quality thin layer films on substrates

    DOEpatents

    Strongin, Myron; Ruckman, Mark; Strongin, Daniel

    1994-01-01

    A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate.

  11. Highly qualified does not equal high quality: A study of urban stakeholders' perceptions of quality in science teaching

    NASA Astrophysics Data System (ADS)

    Miranda, Rommel Joseph

    By employing qualitative methods, this study sought to determine the perceptions that urban stakeholders hold about what characteristics should distinguish a high school science teacher whom they would consider to demonstrate high quality in science teaching. A maximum variation sample of six science teachers, three school administrators, six parents and six students from a large urban public school district were interviewed using semi-structured, in-depth interview techniques. From these data, a list of observable characteristics which urban stakeholders hold as evidence of high quality in science teaching was generated. Observational techniques were utilized to determine the extent to which six urban high school science teachers, who meet the NCLB Act criteria for being "highly qualified", actually possessed the characteristics which these stakeholders hold as evidence of high quality in science teaching. Constant comparative analysis was used to analyze the data set. The findings suggest that urban stakeholders perceive that a high school science teacher who demonstrates high quality in science teaching should be knowledgeable about their subject matter, their student population, and should be resourceful; should possess an academic background in science and professional experience in science teaching; should exhibit professionalism, a passion for science and teaching, and a dedication to teaching and student learning; should be skillful in planning and preparing science lessons and in organizing the classroom, in presenting the subject matter to students, in conducting a variety of hands-on activities, and in managing a classroom; and should assess whether students complete class goals and objectives, and provide feedback about grades for students promptly. The findings further reveal that some of the urban high school science teachers who were deemed to be "highly qualified", as defined by the NCLB Act, engaged in practices that threatened quality in science

  12. Detection of High Quality Rainfall Data to Improve Flood Resilience

    NASA Astrophysics Data System (ADS)

    Hoang, T. C.; Tchiguirinskaia, I.; Schertzer, D. J.; Lovejoy, S.

    2012-12-01

    European flood management systems require reliable rainfall statistics, e.g. the Intensity-duration-Frequency curves for shorter and shorter durations and for a larger and larger range of return periods. Preliminary studies showed that the number of floods depends on the quality of available data, e.g. the time resolution quality. These facts suggest that a particular attention should be paid to the rainfall data quality in order to adequately investigate flood risk aiming to achieve flood resilience. The potential consequences of changes in measuring and recording techniques have been somewhat discussed in the literature with respect to a possible introduction of artificial inhomogeneities in time series. In this direction, we developed a first version of a SERQUAL procedure to automatically detect the effective time resolution of highly mixed data. We show that most of the rainfall time series have a lower recording frequency than that is assumed. This question is particularly important for operational hydrology, because an error on the effective recording high frequency introduces biases in the corresponding statistics. It is therefore essential to quantify the quality of the rainfall time series before their use. Due to the fact that the multiple scales and possible scaling behaviour of hydrological data are particularly important for many applications, including flood resilience research, this paper first investigates the sensitivity of the scaling estimates and methods to the deficit of short duration rainfall data, and consequently propose a few simple criteria for a reliable evaluation of the data quality. The SERQUAL procedure enable us to extract high quality sub-series from longer time series that will be much more reliable to calibrate and/or validate short duration quantiles and hydrological models.

  13. Dissipative soliton protocols in semiconductor microcavities at finite temperatures

    NASA Astrophysics Data System (ADS)

    Karpov, D. V.; Savenko, I. G.; Flayac, H.; Rosanov, N. N.

    2015-08-01

    We consider exciton polaritons in a semiconductor microcavity with a saturable absorber in the growth direction of the heterostructure. This feature promotes additional nonlinear losses of the system with the emergence of bistability of the condensate particles number on the nonresonant (electrical or optical) excitation intensity. Furthermore, we demonstrate a new type of bright spatial dissipative exciton-polariton soliton which emerges in the equilibrium between the regions with different particle density. We develop protocols of soliton creation and destruction. The switch to a solitonlike behavior occurs if the cavity is exposed by a short strong laser pulse with certain energy and duration. We estimate the characteristic times of soliton switch on and off and the time of return to the initial cycle. In particular, we demonstrate surprising narrowing of the spatial profile of the soliton and its vanishing at certain temperature due to interaction of the system with the thermal bath of acoustic phonons. We also address the role of polariton-polariton interaction (Kerr-like nonlinearity) on formation of dissipative solitons and show that the soliton may exist both in its presence and its absence.

  14. Statistics of chaotic resonances in an optical microcavity

    NASA Astrophysics Data System (ADS)

    Wang, Li; Lippolis, Domenico; Li, Ze-Yang; Jiang, Xue-Feng; Gong, Qihuang; Xiao, Yun-Feng

    2016-04-01

    Distributions of eigenmodes are widely concerned in both bounded and open systems. In the realm of chaos, counting resonances can characterize the underlying dynamics (regular vs chaotic), and is often instrumental to identify classical-to-quantum correspondence. Here, we study, both theoretically and experimentally, the statistics of chaotic resonances in an optical microcavity with a mixed phase space of both regular and chaotic dynamics. Information on the number of chaotic modes is extracted by counting regular modes, which couple to the former via dynamical tunneling. The experimental data are in agreement with a known semiclassical prediction for the dependence of the number of chaotic resonances on the number of open channels, while they deviate significantly from a purely random-matrix-theory-based treatment, in general. We ascribe this result to the ballistic decay of the rays, which occurs within Ehrenfest time, and importantly, within the time scale of transient chaos. The present approach may provide a general tool for the statistical analysis of chaotic resonances in open systems.

  15. Microtopographical Characterization of Microcavities on X-Rays Sensor Array

    NASA Astrophysics Data System (ADS)

    Costa, Manuel F. M.

    2008-04-01

    A large number of medical imaging methods, such as computed tomography, ultrasound and magnetic resonance imaging, are for quite some time digital. X-ray imaging was kept analogue until recently. Over last half a dozen years' digital radiography systems are being successfully developed. Among other advantages common to other medical imaging methods, digital X-ray imaging allow an important reduction of the X-ray doses involved in different medical diagnosis. The communication herein reports to the microtopographic inspection of laser ablation opened microcavities during development of an X-rays microdetector based on an array of wells filled with scintillator crystals. The wells were obtained by laser ablation of a 500 microns thick aluminum film. X-ray energy is converted to visible light within the crystals and then detected by a photodetector fabricated in a standard CMOS process. Aluminium thick-films were chosen as present good reflectivity in the visible range improving the amount of photons collected at each photodetector. Square wells 100 microns wide and 490 microns deep were targeted. In this communication we will report on the process of optical microtopographic characterization of the aluminium wells. This metrological process was performed in order to optimize the laser ablation system parameter in order to obtain the desired size square wells with almost vertical smooth sidewalls.

  16. Superfluidity and collective properties of excitonic polaritons in gapped graphene in a microcavity

    NASA Astrophysics Data System (ADS)

    Berman, Oleg L.; Kezerashvili, Roman Ya.; Ziegler, Klaus

    2012-12-01

    We predict the formation and superfluidity of polaritons in an optical microcavity formed by excitons in gapped graphene embedded there and microcavity photons. The Rabi splitting related to the creation of an exciton in a graphene layer in the presence of the band gap is obtained. It is demonstrated that the Rabi splitting decreases when the energy gap increases, while the larger value of the dielectric constant of the microcavity gives a smaller value for the Rabi splitting. The analysis of collective excitations as well as the sound velocity is presented. We show that the superfluid density ns and temperature of the Kosterlitz-Thouless phase transition Tc are decreasing functions of the energy gap.

  17. Random nanostructure scattering layer for suppression of microcavity effect and light extraction in OLEDs.

    PubMed

    Shin, Jin-Wook; Cho, Doo-Hee; Moon, Jaehyun; Joo, Chul Woong; Lee, Jonghee; Huh, Jin Woo; Park, Seung Koo; Han, Jun-Han; Cho, Nam Sung; Hwang, Joohyun; Chu, Hye Yong; Lee, Jeong-Ik

    2014-06-15

    In this study, we investigated the effect of a random nanostructure scattering layer (RSL) on the microcavity and light extraction in organic light emitting diodes (OLEDs). In the case of the conventional OLED, the optical properties change with the thickness of the hole transporting layer (HTL) because of the presence of a microcavity. However, OLEDs equipped with the an RSL showed similar values of external quantum efficiency and luminous efficacy regardless of the HTL thickness. These phenomena can be understood by the scattering effect because of the RSL, which suppresses the microcavity effect and extracts the light confined in the device. Moreover, OLEDs with the RSL led to reduced spectrum and color changes with the viewing angle. PMID:24978528

  18. Realization of Plasmonic Microcavity with Full Transverse and Longitudinal Mode Selection

    NASA Astrophysics Data System (ADS)

    Liu, Ju; Chen, Yue-Gang; Gan, Lin; Xiao, Ting-Hui; Li, Zhi-Yuan

    2016-06-01

    Surface plasmon polaritons (SPPs) manipulation is of vital importance to construct ultracompact integrated micro/nano-optical devices and systems. Here we report the design, fabrication, and characterization of a SPP microcavity with full transverse and longitudinal mode selection and control on the surface of gold film. The designed microcavity supports the fundamental and first-order transverse modes of Gaussian mode beam with controllable longitudinal modes, respectively. The transverse mode is determined by two holographic mirrors made from deliberately designed groove patterns via the surface electromagnetic wave holography methodology, while the longitudinal mode is determined by the length of cavity. Both numerical simulations and leaky-wave SPP mode observations confirm the realization of full mode selection in the fabricated cavity. Our work opens up a powerful way to fully explore longitudinal and transverse mode control in SPP microcavities, which will be beneficial for light-matter interaction enhancement, construction of novel SPP nanolaser and microlaser, optical sensing, and optical information processing.

  19. External pumping of hybrid nanostructures in microcavity with Frenkel and Wannier-Mott excitons

    NASA Astrophysics Data System (ADS)

    Dubovskiy, O. A.; Agranovich, V. M.

    2016-09-01

    The exciton-exciton interaction in hybrid nanostructures with resonating Frenkel and Wannier-Mott excitons was investigated in many publications. In microcavity the hybrid nanostructures can be exposed to different types of optical pumping, the most common one being pumping through one of the microcavity side. However, not investigated and thus never been discussed the hybrid excitons generation by pumping of confined quantum wells from the side of empty microcavity without nanostructures in a wave guided configuration. Here, we consider the hybrid excitations in cavity with organic and inorganic quantum wells and with different types of pumping from external source. The frequency dependence for intensity of excitations in hybrid structure is also investigated. The results may be used for search of most effective fluorescence and relaxation processes. The same approach may be used when both quantum wells are organic or inorganic.

  20. Fabry-Perot microcavity sensor for H2-breath-test analysis

    NASA Astrophysics Data System (ADS)

    Vincenti, Maria Antonietta; De Sario, Marco; Petruzzelli, V.; D'Orazio, Antonella; Prudenzano, Francesco; de Ceglia, Domenico; Scalora, Michael

    2007-10-01

    Leak detection of hydrogen for medical purposes, based on the monitoring of the optical response of a simple Fabry-Perot microcavity, is proposed to investigate either the occurrence of lactose intolerance, or lactose malabsorption condition. Both pathologic conditions result in bacterial overgrowth in the intestine, which causes increased spontaneous emission of H2 in the human breath. Two sensitivity figures of merit are introduced to inspect changes in the sensor response, and to relate the microcavity response to a pathologic condition, which is strictly related to a different level of exhaled hydrogen. Different sensor configurations using a metal-dielectric microcavity are reported and discussed in order to make the most of the well-known ability of palladium to spontaneously absorb hydrogen.

  1. Numerical analysis of pulse signal restoration by stochastic resonance in a buckled microcavity.

    PubMed

    Sun, Heng; Liu, Hongjun; Sun, Qibing; Huang, Nan; Wang, Zhaolu; Han, Jing

    2016-04-20

    A novel scheme is proposed to restore weak pulse signals immersed in noise by stochastic resonance based on photothermal-effect-induced optical bistability in a buckled dome microcavity. The bistable properties of the dome microcavity are analyzed with different initial detuning wavelengths and effective cavity lengths, and bistable transmission can be obtained for input powers in submilliwatt range. A theoretical model is derived to interpret the nonlinear process of pulse signal recovery through double-well potential theory. The cross-correlation coefficient between output signals and pure input pulses is calculated to quantitatively analyze the influence of noise intensity on stochastic resonance. A cross-correlation gain of 7 is obtained, and the noise-hidden signal can be recovered effectively though the buckled dome microcavity with negligible distortion. The simulation results show the potential of using this structure to restore low-level or noise-hidden pulse signals in all-optical integrated systems. PMID:27140110

  2. Non-Hermitian Hamiltonian and Lamb shift in circular dielectric microcavity

    NASA Astrophysics Data System (ADS)

    Park, Kyu-Won; Kim, Jaewan; Jeong, Kabgyun

    2016-06-01

    We study the normal modes and quasi-normal modes (QNMs) in circular dielectric microcavities through non-Hermitian Hamiltonian, which come from the modifications due to system-environment coupling. Differences between the two types of modes are studied in detail, including the existence of resonances tails. Numerical calculations of the eigenvalues reveal the Lamb shift in the microcavity due to its interaction with the environment. We also investigate relations between the Lamb shift and quantized angular momentum of the whispering gallery mode as well as the refractive index of the microcavity. For the latter, we make use of the similarity between the Helmholtz equation and the Schrödinger equation, in which the refractive index can be treated as a control parameter of effective potential. Our result can be generalized to other open quantum systems with a potential term.

  3. High Quality Factor Mechanical Resonators Based on WSe2 Monolayers.

    PubMed

    Morell, Nicolas; Reserbat-Plantey, Antoine; Tsioutsios, Ioannis; Schädler, Kevin G; Dubin, François; Koppens, Frank H L; Bachtold, Adrian

    2016-08-10

    Suspended monolayer transition metal dichalcogenides (TMD) are membranes that combine ultralow mass and exceptional optical properties, making them intriguing materials for opto-mechanical applications. However, the low measured quality factor of TMD resonators has been a roadblock so far. Here, we report an ultrasensitive optical readout of monolayer TMD resonators that allows us to reveal their mechanical properties at cryogenic temperatures. We find that the quality factor of monolayer WSe2 resonators greatly increases below room temperature, reaching values as high as 1.6 × 10(4) at liquid nitrogen temperature and 4.7 × 10(4) at liquid helium temperature. This surpasses the quality factor of monolayer graphene resonators with similar surface areas. Upon cooling the resonator, the resonant frequency increases significantly due to the thermal contraction of the WSe2 lattice. These measurements allow us to experimentally study the thermal expansion coefficient of WSe2 monolayers for the first time. High Q-factors are also found in resonators based on MoS2 and MoSe2 monolayers. The high quality-factor found in this work opens new possibilities for coupling mechanical vibrational states to two-dimensional excitons, valley pseudospins, and single quantum emitters and for quantum opto-mechanical experiments based on the Casimir interaction. PMID:27459399

  4. Detection of MMP-8 via porous silicon microcavity devices functionalized with human antibodies

    NASA Astrophysics Data System (ADS)

    Martin, Marta; Taleb Bendiab, Chakib; Massif, Laurent; Cuisinier, Frédéric J. G.; Gergely, Csilla

    2010-04-01

    In this work we report on the fabrication of functionalized PSiMc scaffolds that can be used to enhance the detection of MMP-8. Matrix metalloproteinases (MMPs) are the major enzymes that degrade extracellular matrix (ECM) proteins and play a key role in diverse physiological and pathological processes. We are interested in detecting the collagenase-type MMP-8 that is an inflammatory marker in gingival fluid for predicting tooth movement during orthodontic treatment. As presence of an increasing amount of MMP-8 in saliva is directly related with the tooth movement during orthodontic treatment, monitoring continuously the MMP-8 variation is primordial. Porous silicon microcavity (PSiMc) structures were prepared as multilayered stacks of low and high refractive indices and with layer thicknesses in the order of visible light wavelength. Then the PSi surface was functionalized with human antibodies. Both functionalization and MMP-8 infiltration were monitored by specular reflectometry. PSiMc is characterized by a narrow resonance peak in the optical spectrum that is very sensitive to a small change in the refractive index, such as that obtained when a molecule is attached to the large internal surface of porous silicon. The pore dimensions of the used PSiMc structures were evaluated by atomic force microscopy (AFM) and scanning electron microscope (SEM).

  5. MBE grown high quality GaN films and devices

    NASA Astrophysics Data System (ADS)

    Kim, W.; Aktas, O.; Salvador, A.; Botchkarev, A.; Sverdlov, B.; Mohammad, S. N.; Morkoç, H.

    1997-02-01

    GaN films with much improved structural, transport, and optical properties have been prepared by molecular beam epitaxy using NH 3 as a nitrogen source. Films with a wide range of resistivity, including highly resistive ones, were grown with a chosen growth rate of 1.2 μm/h. The electron mobility in modulation doped structures is about 450 and 850 cm 2/Vs at 300 and 77 K, respectively, with an areal carrier concentration of about 10 13 cm -2. Low temperature luminescence shows A- and B-free-excitons as well as the excited state of the A- and B-excitons, the first known observation, attesting to the quality of the samples. These transition energies are consistent with the best MOCVD samples and represent a sizable reduction of the pandemic zincblende phase in MBE grown films. The high quality of films was demonstrated by the realization of high performance MODFETs and Schottky diodes.

  6. Output polarization characteristics of a GaN microcavity diode polariton laser

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Aniruddha; Baten, Md Zunaid; Iorsh, Ivan; Frost, Thomas; Kavokin, Alexey; Bhattacharya, Pallab

    2016-07-01

    We report the steady state output polarization characteristics of GaN-based microcavity polariton lasers operated with electrical injection at room temperature. The output is unpolarized below the nonlinear threshold injection current and is linearly polarized above it with a maximum degree of polarization of ˜22 % . The results have been analyzed theoretically, and the calculated results are in agreement with the measured data. We have also measured the polarization-resolved output light current characteristics, wherein a distinct lowering of the non-linear threshold is observed in one device. This is interpreted in terms of spatially inhomogeneous lifting of degeneracy and polarization splitting in the microcavity.

  7. Hydrostatic pressure sensor based on micro-cavities developed by the catastrophic fuse effect

    NASA Astrophysics Data System (ADS)

    Domingues, M. F.; Paixão, T.; Mesquita, E.; Alberto, N.; Antunes, P.; Varum, H.; André, P. S.

    2015-09-01

    In this work, an optical fiber hydrostatic pressure sensor based in Fabry-Perot micro-cavities is presented. These micro structures were generated by the recycling of optical fiber previously damaged by the fiber fuse effect, resulting in a cost effective solution when compared with the traditional methods used to produce similar micro-cavities. The developed sensor was tested for pressures ranging from 20.0 to 190.0 cmH2O and a sensitivity of 53.7 +/- 2.6 pm/cmH2O for hydrostatic pressures below to 100 cmH2O was achieved.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  9. Geometry Dependent Evolution of the Resonant Mode in ZnO Elongated Hexagonal Microcavity

    PubMed Central

    Dong, Hongxing; Liu, Yang; Sun, Shulin; Li, Jingzhou; Zhan, Jinxin; Chen, Zhanghai; Zhang, Long

    2016-01-01

    We have developed a novel but simple approach to obtain ZnO microcombs with parallelogram stems and elongated hexagonal branches. We found that the present elongated hexagonal microcavity exhibited quite different features for its optical resonant modes due to the broken hexagonal symmetry. The resonant mode evolution of such microcavity was investigated systemically by using a spatially resolved spectroscopic technique. Theoretical analyses based on the plane wave mode and FEM simulations agreed well with the experimental results. We believe that our research allows us to have a deeper understanding of the controllable growth of novel optical cavities and the shape-dependent optical resonant modes. PMID:26763937

  10. Enhanced color conversion from colloidal CdSe/CdS dot/rods by vertical microcavities

    NASA Astrophysics Data System (ADS)

    Pühringer, H.; Roither, J.; Kovalenko, M. V.; Eibelhuber, M.; Schwarzl, T.; Talapin, D. V.; Heiss, W.

    2010-09-01

    Colloidal CdSe/CdS dot/rods exhibit efficient photoluminescence from the spherical CdSe dots at wavelengths well below the absorption edge of the rod material. This property makes dot/rods advantageous for color conversion applications, especially when they are embedded in optical microcavities to improve light extraction in forward direction. Here, surface emitting half-wavelength microcavities are demonstrated containing films of dot/rods as active material, exhibiting luminescence enhancement factors of up to 21 at the resonator wavelengths, whereas with conventional CdSe/ZnS core-shell nanocrystals only half of this value is obtained.

  11. Strong coupling and polariton lasing in Te based microcavities embedding (Cd,Zn)Te quantum wells

    SciTech Connect

    Rousset, J.-G. Piętka, B.; Król, M.; Mirek, R.; Lekenta, K.; Szczytko, J.; Borysiuk, J.; Suffczyński, J.; Kazimierczuk, T.; Goryca, M.; Smoleński, T.; Kossacki, P.; Nawrocki, M.; Pacuski, W.

    2015-11-16

    We report on properties of an optical microcavity based on (Cd,Zn,Mg)Te layers and embedding (Cd,Zn)Te quantum wells. The key point of the structure design is the lattice matching of the whole structure to MgTe, which eliminates the internal strain and allows one to embed an arbitrary number of unstrained quantum wells in the microcavity. We evidence the strong light-matter coupling regime already for the structure containing a single quantum well. Embedding four unstrained quantum wells results in further enhancement of the exciton-photon coupling and the polariton lasing in the strong coupling regime.

  12. Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities

    PubMed Central

    Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2015-01-01

    Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits. PMID:26225781

  13. Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities.

    PubMed

    Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2015-01-01

    Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits. PMID:26225781

  14. Hyper CNOT and Hyper Bell-State Analysis Assisted by Quantum Dots in Double-Side Optical Microcavities

    NASA Astrophysics Data System (ADS)

    He, Yong; Deng, Yun; Li, Hui-Ran; Luo, Ming-Xing

    2016-03-01

    There are many important works about the construction of universal quantum logic gates which are key elements in quantum computation. However, most of them focus on quantum transformations on the same degree of freedom (DOF) of quantum systems. We propose a CNOT gate performed on the polarization DOF and spatial mode DOF of one photon system assisted by a quantum dot in double-side optical microcavities. This hyper CNOT gate is implemented by using spin selective photon reflection from the cavity, without auxiliary spatial modes or polarization modes. This interface can also be used to construct a hyper photonic Bell-state analyzer. The high fidelities of the hyper CNOT gates may be achieved with low side leakage and cavity loss.

  15. Accurate simulation of two-dimensional optical microcavities with uniquely solvable boundary integral equations and trigonometric Galerkin discretization.

    PubMed

    Boriskina, Svetlana V; Sewell, Phillip; Benson, Trevor M; Nosich, Alexander I

    2004-03-01

    A fast and accurate method is developed to compute the natural frequencies and scattering characteristics of arbitrary-shape two-dimensional dielectric resonators. The problem is formulated in terms of a uniquely solvable set of second-kind boundary integral equations and discretized by the Galerkin method with angular exponents as global test and trial functions. The log-singular term is extracted from one of the kernels, and closed-form expressions are derived for the main parts of all the integral operators. The resulting discrete scheme has a very high convergence rate. The method is used in the simulation of several optical microcavities for modern dense wavelength-division-multiplexed systems. PMID:15005404

  16. Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities

    NASA Astrophysics Data System (ADS)

    Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2015-07-01

    Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits.

  17. Coupling of a single diamond nanocrystal to a whispering-gallery microcavity: Photon transport benefitting from Rayleigh scattering

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Chun; Xiao, Yun-Feng; Li, Bei-Bei; Jiang, Xue-Feng; Li, Yan; Gong, Qihuang

    2011-07-01

    We study the Rayleigh scattering induced by a diamond nanocrystal in a whispering-gallery-microcavity-waveguide coupling system and find that it plays a significant role in the photon transportation. On the one hand, this study provides insight into future solid-state cavity quantum electrodynamics aimed at understanding strong-coupling physics. On the other hand, benefitting from this Rayleigh scattering, effects such as dipole-induced transparency and strong photon antibunching can occur simultaneously. As a potential application, this system can function as a high-efficiency photon turnstile. In contrast to B. Dayan [ScienceSCIEAS0036-807510.1126/science.1152261 319, 1062 (2008)], the photon turnstiles proposed here are almost immune to the nanocrystal’s azimuthal position.

  18. Coupling of a single diamond nanocrystal to a whispering-gallery microcavity: Photon transport benefitting from Rayleigh scattering

    SciTech Connect

    Liu Yongchun; Xiao Yunfeng; Li Beibei; Jiang Xuefeng; Li Yan; Gong Qihuang

    2011-07-15

    We study the Rayleigh scattering induced by a diamond nanocrystal in a whispering-gallery-microcavity-waveguide coupling system and find that it plays a significant role in the photon transportation. On the one hand, this study provides insight into future solid-state cavity quantum electrodynamics aimed at understanding strong-coupling physics. On the other hand, benefitting from this Rayleigh scattering, effects such as dipole-induced transparency and strong photon antibunching can occur simultaneously. As a potential application, this system can function as a high-efficiency photon turnstile. In contrast to B. Dayan et al. [Science 319, 1062 (2008)], the photon turnstiles proposed here are almost immune to the nanocrystal's azimuthal position.

  19. Effective preparation of the N-dimension spin Greenberger-Horne-Zeilinger state with quantum dots embedded in microcavities

    NASA Astrophysics Data System (ADS)

    Kang, Yi-Hao; Xia, Yan; Lu, Pei-Min; Song, Jie

    2016-07-01

    We propose a scheme for preparation of the N-dimension spin Greenberger-Horne-Zeilinger state by exploiting quantum dots (QDs) embedded in microcavities. Numerically analysed results show that with the spin-selective photon reflection from the cavity, we can complete the scheme assisted by one polarized photon with high fidelity and 100% successful probability in principle. Furthermore, the set-up is just composed of simple linear optical elements, delay lines and conventional photon detectors, which are feasible with existing experimental technology. Moreover, QDs have numerous admirable features in weak-coupling regime, which are practicable in realistic cavity quantum electrodynamics system shown by previous numerical simulations and experiments. Therefore, our scheme might be realized in near future.

  20. [Candidate gene analysis of high quality merino sheep].

    PubMed

    Liu, Gui-Fen; Tian, Ke-Chuan; Zhang, En-Ping; Huang, Xi-Xia; Zhang, Yan-Hua

    2007-01-01

    Partial sequences of wool fiber constituent genes KAP1.1 and KAP1.3 and the exonic sequence of the KAP6.1 gene were chosen for polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis to assess their ability as candidate genes during indirect selection for fine wool traits. Results show that locus W08667 in the genes (KAP1.1, KAP1.3) which code the high sulfur protein associated-protein of keratin associated-protein family is significantly correlated with fine wool quality (P < 0.05). Among the high-glycine-tyrosine keratin associated- protein, the AA and BB genotypes of W06933 are also significantly correlated with fine wool quality (P < 0.05). PMID:17284427

  1. Auto Spell Suggestion for High Quality Speech Synthesis in Hindi

    NASA Astrophysics Data System (ADS)

    Kabra, Shikha; Agarwal, Ritika

    2014-02-01

    The goal of Text-to-Speech (TTS) synthesis in a particular language is to convert arbitrary input text to intelligible and natural sounding speech. However, for a particular language like Hindi, which is a highly confusing language (due to very close spellings), it is not an easy task to identify errors/mistakes in input text and an incorrect text degrade the quality of output speech hence this paper is a contribution to the development of high quality speech synthesis with the involvement of Spellchecker which generates spell suggestions for misspelled words automatically. Involvement of spellchecker would increase the efficiency of speech synthesis by providing spell suggestions for incorrect input text. Furthermore, we have provided the comparative study for evaluating the resultant effect on to phonetic text by adding spellchecker on to input text.

  2. Going to Scale with High-Quality Early Education

    ERIC Educational Resources Information Center

    Christina, Rachel; Nicholson-Goodman, JoVictoria

    2005-01-01

    This report is an initial effort to describe efforts of a number of states that are seeking to create statewide systems of high-quality pre-kindergarten services, as well as some of the progress they have made in doing so. Focusing on the efforts of a sample of eight U.S. states, it examines the policy choices that states have made when…

  3. Magnetic properties of high quality superconducting laser ablated thin films

    NASA Astrophysics Data System (ADS)

    Berling, D.; Loegel, B.; Mehdaoui, A.; Acquaviva, S.; Leggieri, G.; Luches, A.; Del Vecchio, A.; Tapfer, L.

    1998-05-01

    We present experimental results obtained forRBa2Cu3O7 - x(R = Y,Er) expitaxial thin films obtained through pulsed laser deposition (PLD) and grown on yttria stabilized zirconia (YSZ) and SrTiO3(STO) substrates. The films have been deposited by using low deposition rates (f = 4 Hz) and with control of the film surface temperature rather than that of the sample holder leading to a high quality of the epitaxy.

  4. A high-throughput, high-quality plant genomic DNA extraction protocol.

    PubMed

    Li, H; Li, J; Cong, X H; Duan, Y B; Li, L; Wei, P C; Lu, X Z; Yang, J B

    2013-01-01

    The isolation of high-quality genomic DNA (gDNA) is a crucial technique in plant molecular biology. The quality of gDNA determines the reliability of real-time polymerase chain reaction (PCR) analysis. In this paper, we reported a high-quality gDNA extraction protocol optimized for real-time PCR in a variety of plant species. Performed in a 96-well block, our protocol provides high throughput. Without the need for phenol-chloroform and liquid nitrogen or dry ice, our protocol is safer and more cost-efficient than traditional DNA extraction methods. The method takes 10 mg leaf tissue to yield 5-10 µg high-quality gDNA. Spectral measurement and electrophoresis were used to demonstrate gDNA purity. The extracted DNA was qualified in a restriction enzyme digestion assay and conventional PCR. The real-time PCR amplification was sufficiently sensitive to detect gDNA at very low concentrations (3 pg/µL). The standard curve of gDNA dilutions from our phenol-chloroform-free protocol showed better linearity (R(2) = 0.9967) than the phenol-chloroform protocol (R(2) = 0.9876). The results indicate that the gDNA was of high quality and fit for real-time PCR. This safe, high-throughput plant gDNA extraction protocol could be used to isolate high-quality gDNA for real-time PCR and other downstream molecular applications. PMID:24222228

  5. High-performance conformal sensors employing single-crystal silicon nanomembranes

    NASA Astrophysics Data System (ADS)

    Xu, Xiaochuan; Subbaraman, Harish; Chakravarty, Swapnajit; Chen, Ray T.

    2014-03-01

    We demonstrate light-weight, conformal, and high-performance flexible sensors fabricated on a large area (>2 cm × 2 cm) silicon nanomembrane transferred onto a flexible substrate. Linear L13 photonic crystal microcavities are designed to provide high quality factors on the flexible platform. Subwavelength grating (SWG) couplers are employed in order to enable efficient light coupling to the device using a single mode fiber. Photonic crystal tapers are implemented at the strip-photonic crystal waveguide interfaces to minimize loss. Preliminary chemical sensing data suggests a sensitivity of 75nm/RIU. Bending tests are further performed in order to demonstrate sensitivityindependent operation.

  6. High quality fuel gas from biomass pyrolysis with calcium oxide.

    PubMed

    Zhao, Baofeng; Zhang, Xiaodong; Chen, Lei; Sun, Laizhi; Si, Hongyu; Chen, Guanyi

    2014-03-01

    The removal of CO2 and tar in fuel gas produced by biomass thermal conversion has aroused more attention due to their adverse effects on the subsequent fuel gas application. High quality fuel gas production from sawdust pyrolysis with CaO was studied in this paper. The results of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments indicate that the mass ratio of CaO to sawdust (Ca/S) remarkably affects the behavior of sawdust pyrolysis. On the basis of Py-GC/MS results, one system of a moving bed pyrolyzer coupled with a fluid bed combustor has been developed to produce high quality fuel gas. The lower heating value (LHV) of the fuel gas was above 16MJ/Nm(3) and the content of tar was under 50mg/Nm(3), which is suitable for gas turbine application to generate electricity and heat. Therefore, this technology may be a promising route to achieve high quality fuel gas for biomass utilization. PMID:24486940

  7. Polariton lasing vs. photon lasing in a semiconductor microcavity

    PubMed Central

    Deng, Hui; Weihs, Gregor; Snoke, David; Bloch, Jacqueline; Yamamoto, Yoshihisa

    2003-01-01

    Nearly one decade after the first observation of Bose–Einstein condensation in atom vapors and realization of matter-wave (atom) lasers, similar concepts have been demonstrated recently for polaritons: half-matter, half-light quasiparticles in semiconductor microcavities. The half-light nature of polaritons makes polariton lasers promising as a new source of coherent and nonclassical light with extremely low threshold energy. The half-matter nature makes polariton lasers a unique test bed for many-body theories and cavity quantum electrodynamics. In this article, we present a series of experimental studies of a polariton laser, exploring its properties as a relatively dense degenerate Bose gas and comparing it to a photon laser achieved in the same structure. The polaritons have an effective mass that is twice the cavity photon effective mass, yet seven orders of magnitude less than the hydrogen atom mass; hence, they can potentially condense at temperatures seven orders of magnitude higher than those required for atom Bose–Einstein condensations. Accompanying the phase transition, a polariton laser emits coherent light but at a threshold carrier density two orders of magnitude lower than that needed for a normal photon laser in a same structure. It also is shown that, beyond threshold, the polariton population splits to a thermal equilibrium Bose–Einstein distribution at in-plane wave number k∥ > 0 and a nonequilibrium condensate at k∥ > 0, with a chemical potential approaching to zero. The spatial distributions and polarization characteristics of polaritons also are discussed as unique signatures of a polariton laser. PMID:14673089

  8. High quality mask storage in an advanced Logic-Fab

    NASA Astrophysics Data System (ADS)

    Jähnert, Carmen; Fritsche, Silvio

    2012-02-01

    High efficient mask logistics as well as safe and high quality mask storage are essential requirements within an advanced lithography area of a modern logic waferfab. Fast operational availability of the required masks at the exposure tool with excellent mask condition requires a safe mask handling, safeguarding of high mask quality over the whole mask usage time without any quality degradation and an intelligent mask logistics. One big challenge is the prevention of haze on high advanced phase shift masks used in a high volume production line for some thousands of 248nm or 193nm exposures. In 2008 Infineon Dresden qualified a customer specific developed semi-bare mask storage system from DMSDynamic Micro Systems in combination with a high advanced mask handling and an interconnected complex logistic system. This high-capacity mask storage system DMS M1900.22 for more than 3000 masks with fully automated mask and box handling as well as full-blown XCDA purge has been developed and adapted to the Infineon Lithotoollandscape using Nikon and SMIF reticle cases. Advanced features for ESD safety and mask security, mask tracking via RFID and interactions with the exposure tools were developed and implemented. The stocker is remote controlled by the iCADA-RSM system, ordering of the requested mask directly from the affected exposure tool allows fast access. This paper discusses the advantages and challenges for this approach as well as the practical experience gained during the implementation of the new system which improves the fab performance with respect to mask quality, security and throughput. Especially the realization of an extremely low and stable humidity level in addition with a well controlled air flow at each mask surface, preventing masks from haze degradation and particle contamination, turns out to be a notable technical achievement. The longterm stability of haze critical masks has been improved significantly. Relevant environmental parameters like

  9. [High-quality hospital discharge summaries - general practitioners expectations].

    PubMed

    Bally, Klaus; Lingenhel, Sabine; Tschudi, Peter

    2012-01-01

    Hospital discharge summaries ensure treatment continuity after hospital discharge. In Switzerland discharge letters are a celebrated custom and a tool for training young colleagues. The primary purpose is to guarantee high-quality care of patients treated by hospital staff and general practitioners. From the perspective of the patient's general practitioner discharge summaries should convey current and accurate medically important patient data to the physician responsible for follow-up care. In the era of highly developed electronic data transfer and introduction of diagnose related groups (DRGs), it will be necessary to transmit hospital discharge information selectively to different target groups. Nevertheless data protection and medical secret must be complied with. PMID:22198930

  10. Microcavity light emitters and microbolometer detectors for gas monitoring in the 2-5 μm range

    NASA Astrophysics Data System (ADS)

    Mottin, Eric; Ballet, Philippe; Levy, Francois; Mathieu, L.; Ouvrier-Buffet, Jean Louis; Rothman, J.; Yon, Jean Jacques; Hadji, Emmanuel; Picard, Emmanuel

    2005-03-01

    A sensor based on selective optical absorption allows monitoring of hazardous engine exhaust emissions such as gaseous hydrocarbons and carbon monoxide. The IR components presented here offer the potential to develop a compact, fast and selective sensor reaching the technical and cost requirements for on-board automotive applications. Optical gas monitoring requires light sources above 3 μm since most of the gas species have their fundamental absorption peaks between 3 and 6 μm. We report here on resonant microcavity light sources emitting at room temperature between 3 and 5 μm. The emitter combines a CdxHg1-xTe light emitting heterostructure and two dielectric multilayered mirrors. It is optically pumped by a commercial III-V laser diode. The principle of the resonant microcavity emitter allows tailoring of the emission wavelength and the line width to fit the absorption band of a specific gas, ensuring a very good selectivity between species. Moreover, this kind of emitter allows fast modulation enabling high detectivity and short response time. We report performances of light sources in the range 3 - 5 μm allowing the detection of hydrocarbons and carbon monoxide. Association of emitters peaking at different characteristic wavelengths with a single broad band detector allows designing of an optical sensor for several gas species. Sensitivity and time response issues have been characterized: detection of less than 50 ppm of CH4 on a 15 cm path has been demonstrated on synthetic gas; analysis of exhaust gases from a vehicle has allowed the resolution of a cylinder time. This optical sensor offers the potential of various on-board automotive applications.

  11. High-throughput Protein Purification and Quality Assessment for Crystallization

    PubMed Central

    Kim, Youngchang; Babnigg, Gyorgy; Jedrzejczak, Robert; Eschenfeldt, William H.; Li, Hui; Maltseva, Natalia; Hatzos-Skintges, Catherine; Gu, Minyi; Makowska-Grzyska, Magdalena; Wu, Ruiying; An, Hao; Chhor, Gekleng; Joachimiak, Andrzej

    2012-01-01

    The ultimate goal of structural biology is to understand the structural basis of proteins in cellular processes. In structural biology, the most critical issue is the availability of high-quality samples. “Structural biology-grade” proteins must be generated in the quantity and quality suitable for structure determination using X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. The purification procedures must reproducibly yield homogeneous proteins or their derivatives containing marker atom(s) in milligram quantities. The choice of protein purification and handling procedures plays a critical role in obtaining high-quality protein samples. With structural genomics emphasizing a genome-based approach in understanding protein structure and function, a number of unique structures covering most of the protein folding space have been determined and new technologies with high efficiency have been developed. At the Midwest Center for Structural Genomics (MCSG), we have developed semi-automated protocols for high-throughput parallel protein expression and purification. A protein, expressed as a fusion with a cleavable affinity tag, is purified in two consecutive immobilized metal affinity chromatography (IMAC) steps: (i) the first step is an IMAC coupled with buffer-exchange, or size exclusion chromatography (IMAC-I), followed by the cleavage of the affinity tag using the highly specific Tobacco Etch Virus (TEV) protease; [1] the second step is IMAC and buffer exchange (IMAC-II) to remove the cleaved tag and tagged TEV protease. These protocols have been implemented on multidimensional chromatography workstations and, as we have shown, many proteins can be successfully produced in large-scale. All methods and protocols used for purification, some developed by MCSG, others adopted and integrated into the MCSG purification pipeline and more recently the Center for Structural Genomics of Infectious Diseases (CSGID) purification pipeline, are

  12. High Quality Down Lighting Luminaire with 73% Overall System Efficiency

    SciTech Connect

    Robert Harrison; Steven C. Allen; Joseph Bernier; Robert Harrison

    2010-08-31

    This report summarizes work to develop a high flux, high efficiency LED-based downlight at OSRAM SYLVANIA under US Department of Energy contract DE-FC26-08NT01582. A new high power LED and electronic driver were developed for these downlights. The LED achieved 100 lumens per watt efficacy and 1700 lumen flux output at a correlated color temperature of 3500K. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.99, and total harmonic distortion <10%. Two styles of downlights using the LED and driver were shown to exceed the project targets for steady-state luminous efficacy and flux of 70 lumens per watt and 1300 lumens, respectively. Compared to similar existing downlights using compact fluorescent or LED sources, these downlights had much higher efficacy at nearly the same luminous flux.

  13. Novel technique for high-quality microstructuring with excimer lasers

    NASA Astrophysics Data System (ADS)

    Roth, Stephan; Geiger, Manfred

    2000-06-01

    Laser micromachining has become increasingly established in many microsystem applications during the past years. These new fields occasion higher demands on the quality of micromachiend devices combined with high resolution and working velocity. Due to the disadvantages of conventional excimer laser processing, a novel technique is required to meet these demands. The main problems of conventional excimer laser machining are the redeposition of ablated material on the irradiated work piece and the formation of a strong melting phase especially for metals. These difficulties greatly reduce the applicability of excimer laser material processing for manufacturing microsystems technology components. By applying a thin water film to the substrate surface, the redeposition of ablated material can be completely avoided, which results in a better quality of the microstructures. Usage of a water film, however, has proved to lead to a marked reduction of the ablation rate for the examined materials - ceramics and stainless steel. Therefore, one of the objectives of future research will be to raise the ablation rate in order to render excimer laser processing more interesting economically. Adding alcoholic additives, among others, has improved the wetting of the liquid films on the surface. The effect of the modified chemical composition of the liquid on ablation rate and structure quality for various materials is presented here.

  14. Fat Quality Influences the Obesogenic Effect of High Fat Diets.

    PubMed

    Crescenzo, Raffaella; Bianco, Francesca; Mazzoli, Arianna; Giacco, Antonia; Cancelliere, Rosa; di Fabio, Giovanni; Zarrelli, Armando; Liverini, Giovanna; Iossa, Susanna

    2015-11-01

    High fat and/or carbohydrate intake are associated with an elevated risk for obesity and chronic diseases such as diabetes and cardiovascular diseases. The harmful effects of a high fat diet could be different, depending on dietary fat quality. In fact, high fat diets rich in unsaturated fatty acids are considered less deleterious for human health than those rich in saturated fat. In our previous studies, we have shown that rats fed a high fat diet developed obesity and exhibited a decrease in oxidative capacity and an increase in oxidative stress in liver mitochondria. To investigate whether polyunsaturated fats could attenuate the above deleterious effects of high fat diets, energy balance and body composition were assessed after two weeks in rats fed isocaloric amounts of a high-fat diet (58.2% by energy) rich either in lard or safflower/linseed oil. Hepatic functionality, plasma parameters, and oxidative status were also measured. The results show that feeding on safflower/linseed oil diet attenuates the obesogenic effect of high fat diets and ameliorates the blood lipid profile. Conversely, hepatic steatosis and mitochondrial oxidative stress appear to be negatively affected by a diet rich in unsaturated fatty acids. PMID:26580650

  15. Fat Quality Influences the Obesogenic Effect of High Fat Diets

    PubMed Central

    Crescenzo, Raffaella; Bianco, Francesca; Mazzoli, Arianna; Giacco, Antonia; Cancelliere, Rosa; di Fabio, Giovanni; Zarrelli, Armando; Liverini, Giovanna; Iossa, Susanna

    2015-01-01

    High fat and/or carbohydrate intake are associated with an elevated risk for obesity and chronic diseases such as diabetes and cardiovascular diseases. The harmful effects of a high fat diet could be different, depending on dietary fat quality. In fact, high fat diets rich in unsaturated fatty acids are considered less deleterious for human health than those rich in saturated fat. In our previous studies, we have shown that rats fed a high fat diet developed obesity and exhibited a decrease in oxidative capacity and an increase in oxidative stress in liver mitochondria. To investigate whether polyunsaturated fats could attenuate the above deleterious effects of high fat diets, energy balance and body composition were assessed after two weeks in rats fed isocaloric amounts of a high-fat diet (58.2% by energy) rich either in lard or safflower/linseed oil. Hepatic functionality, plasma parameters, and oxidative status were also measured. The results show that feeding on safflower/linseed oil diet attenuates the obesogenic effect of high fat diets and ameliorates the blood lipid profile. Conversely, hepatic steatosis and mitochondrial oxidative stress appear to be negatively affected by a diet rich in unsaturated fatty acids. PMID:26580650

  16. High-quality Italian rice cultivars: chemical indices of ageing and aroma quality.

    PubMed

    Griglione, Alessandra; Liberto, Erica; Cordero, Chiara; Bressanello, Davide; Cagliero, Cecilia; Rubiolo, Patrizia; Bicchi, Carlo; Sgorbini, Barbara

    2015-04-01

    The volatile fractions of six Italian high-quality rice cultivars were investigated by HS-SPME-GC-MS to define fingerprinting and identify chemical markers and/or indices of ageing and aroma quality. In particular, four non-aromatic (Carnaroli, Carnise, Cerere and Antares) and two aromatic (Apollo and Venere) rices, harvested in 2010 and 2011, were monitored over 12months. Twenty-five aroma components were considered and, despite considerable inter-annual variability, some of them showed similar trends over time, including 2-(E)-octenal as a marker of ageing for all cultivars, and heptanal, octanal and 2-ethyl hexanol as cultivar-specific indicators. The area ratios 2-acetyl-1-pyrroline/1-octen-3-ol, for Venere, and 3-methyl-1-butanol/2-methyl-1-butanol, for Apollo, were also found to act as ageing indices. Additional information on release of key-aroma compounds was also obtained from quantitation and its dependence on grain shape and chemical composition. Heptanal/1-octen-3-ol and heptanal/octanal ratios were also defined as characterising the aroma quality indices of the six Italian rice cultivars investigated. PMID:25442558

  17. Essential Elements of High Performing, High Quality Part C Systems. NECTAC Notes No. 25

    ERIC Educational Resources Information Center

    Lucas, Anne; Hurth, Joicey; Kasprzak, Christina

    2010-01-01

    National Early Childhood Technical Assistance Center (NECTAC) was asked to identify essential elements for supporting high performance and provision of high quality early intervention Part C services as determined by the Annual Performance Review (APR) required under Individuals with Disabilities Education Act (IDEA). To respond, NECTAC…

  18. Teacher Resilience in High-Poverty Schools: How Do High-Quality Teachers Become Resilient?

    ERIC Educational Resources Information Center

    Merrill, Kate Mansi

    2013-01-01

    The primary purpose of this study was to understand how high-quality teachers who began their career through Teach For America (TFA) became resilient while teaching in challenging, high-poverty schools. A secondary purpose of this study was to ascertain how, if at all, the teaching experiences of TFA teachers who stayed in the profession differed…

  19. Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect

    NASA Astrophysics Data System (ADS)

    Yüce, Emre; Ctistis, Georgios; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L.

    2016-01-01

    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities that operate in the "Original" (O) telecom band by exploiting the instantaneous electronic Kerr effect. We observe that the resonance frequency reversibly shifts within one picosecond. We investigate experimentally and theoretically the role of several main parameters: the material backbone and its electronic bandgap, the pump power, the quality factor, and the duration of the switch pulse. The magnitude of the shift is reduced when the backbone of the central $\\lambda-$layer has a greater electronic bandgap; pumping with photon energies near the bandgap resonantly enhances the switched magnitude. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the duration matches the cavity storage time that is set by the quality factor. We provide the settings for the essential parameters so that the frequency shift of the cavity resonance can be increased to one linewidth.

  20. Percutaneous vertebroplasty with a high-quality rotational angiographic unit.

    PubMed

    Pedicelli, Alessandro; Rollo, Massimo; Piano, Mariangela; Re, Thomas J; Cipriani, Maria C; Colosimo, Cesare; Bonomo, Lorenzo

    2009-02-01

    We evaluated the reliability of a rotational angiographic unit (RA) with flat-panel detector as a single technique to guide percutaneous vertebroplasty (PVP) and for post-procedure assessment by 2D and 3D reformatted images. Fifty-five consecutive patients (104 vertebral bodies) were treated under RA fluoroscopy. Rotational acquisitions with 2D and 3D reconstruction were obtained in all patients for immediate post-procedure assessment. In complex cases, this technique was also used to evaluate the needle position during the procedure. All patients underwent CT scan after the procedure. RA and CT findings were compared. In all cases, a safe trans-pedicular access and an accurate control of the bone-cement injection were successfully performed with high-quality fluoroscopy, even at the thoracic levels and in case of vertebra plana. 2D and 3D rotational reconstructions permitted CT-like images that clearly showed needle position and were similar to CT findings in depicting intrasomatic implant-distribution. RA detected 40 cement leakages compared to 42 demonstrated by CT and showed overall 95% sensitivity and 100% specificity compared to CT for final post-procedure assessment. Our preliminary results suggest that high-quality RA is reliable and safe as a single technique for PVP guidance, control and post-procedure assessment. It permits fast and cost-effective procedures avoiding multi-modality imaging. PMID:19230069

  1. Effect of Threading Dislocations on the Quality Factor of InGaN/GaN Microdisk Cavities

    PubMed Central

    2014-01-01

    In spite of the theoretical advantages associated with nitride microcavities, the quality factors of devices with embedded indium gallium nitride (InGaN) or gallium nitride (GaN) optical emitters still remain low. In this work we identify threading dislocations (TDs) as a major limitation to the fabrication of high quality factor devices in the nitrides. We report on the use of cathodoluminescence (CL) to identify individual TD positions within microdisk lasers containing either InGaN quantum wells or quantum dots. Using CL to accurately count the number, and map the position, of dislocations within several individual cavities, we have found a clear correlation between the density of defects in the high-field region of a microdisk and its corresponding quality factor (Q). We discuss possible mechanisms associated with defects, photon scattering, and absorption, which could be responsible for degraded device performance. PMID:25839048

  2. Automated Theorem Proving in High-Quality Software Design

    NASA Technical Reports Server (NTRS)

    Schumann, Johann; Swanson, Keith (Technical Monitor)

    2001-01-01

    The amount and complexity of software developed during the last few years has increased tremendously. In particular, programs are being used more and more in embedded systems (from car-brakes to plant-control). Many of these applications are safety-relevant, i.e. a malfunction of hardware or software can cause severe damage or loss. Tremendous risks are typically present in the area of aviation, (nuclear) power plants or (chemical) plant control. Here, even small problems can lead to thousands of casualties and huge financial losses. Large financial risks also exist when computer systems are used in the area of telecommunication (telephone, electronic commerce) or space exploration. Computer applications in this area are not only subject to safety considerations, but also security issues are important. All these systems must be designed and developed to guarantee high quality with respect to safety and security. Even in an industrial setting which is (or at least should be) aware of the high requirements in Software Engineering, many incidents occur. For example, the Warshaw Airbus crash, was caused by an incomplete requirements specification. Uncontrolled reuse of an Ariane 4 software module was the reason for the Ariane 5 disaster. Some recent incidents in the telecommunication area, like illegal "cloning" of smart-cards of D2GSM handies, or the extraction of (secret) passwords from German T-online users show that also in this area serious flaws can happen. Due to the inherent complexity of computer systems, most authors claim that only a rigorous application of formal methods in all stages of the software life cycle can ensure high quality of the software and lead to real safe and secure systems. In this paper, we will have a look, in how far automated theorem proving can contribute to a more widespread application of formal methods and their tools, and what automated theorem provers (ATPs) must provide in order to be useful.

  3. High quality GPU rendering with displaced pixel shading

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Choi, Jae

    2006-03-01

    Direct volume rendering via consumer PC hardware has become an efficient tool for volume visualization. In particular, the volumetric ray casting, the most frequently used volume rendering technique, can be implemented by the shading language integrated with graphical processing units (GPU). However, to produce high-quality images offered by GPU-based volume rendering, a higher sampling rate is usually required. In this paper, we present an algorithm to generate high quality images with a small number of slices by utilizing displaced pixel shading technique. Instead of sampling points along a ray with the regular interval, the actual surface location is calculated by the linear interpolation between the outer and inner points, and this location is used as the displaced pixel for the iso-surface illumination. Multi-pass and early Z-culling techniques are applied to improve the rendering speed. The first pass simply locates and stores the exact surface depth of each ray using a few pixel instructions; then, the second pass uses instructions to shade the surface at the previous position. A new 3D edge detector from our previous research is integrated to provide more realistic rendering results compared with the widely used gradient normal estimator. To implement our algorithm, we have made a program named DirectView based on DirectX 9.0c and Microsoft High Level Shading Language (HLSL) for volume rendering. We tested two data sets and discovered that our algorithm can generate smoother and more accurate shading images with a small number of intermediate slices.

  4. Environmental Quality Assessment of Built Areas with High Vacancy

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Yuan, Y.; Neale, A. C.

    2015-12-01

    Around the world, many urban areas are challenged by vacant and abandoned residential and business property. High vacancy areas have often been associated with increasing public safety problems and declining property values and subsequent tax base. High vacancy can lead to visible signs of city decline and significant barriers to the revitalization of cities. Addressing the problem of vacancy requires knowledge of vacancy patterns and their possible contributing factors. In this study, we evaluated the ten year (2005-2015) urban environmental changes for some high vacancy areas. Social and economic variables derived from U.S. census data such as non-white population, employment rate, housing price, and environmental variables derived from National Land Cover Data such as land cover and impervious area, were used as the basis for analysis. Correlation analysis and principle components analysis were performed at the Census Block Group level. Three components were identified and interpreted as economic status, urbanness, and greenness. A synthetic Urban Environmental Quality (UEQ) index was developed by integrating the three principle components according to their weights. Comparisons of the UEQ indices between the 2005 and 2015 in the increasingly high vacancy area provided useful information for investigating the possible associations between social, economic, and environmental factors, and the vacancy status. This study could provide useful information for understanding the complex issues leading to vacancy and facilitating future rehabilitation of vacant urban area.

  5. Handling qualities of the High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Solies, U. Peter

    1994-01-01

    The low speed handling qualities of a High Speed Civil Transport class aircraft have been investigated by using data of the former Advanced Supersonic Transport (AST) 105. The operation of such vehicles in the airport terminal area is characterized by 'backside' performance. Main objectives of this research effort were: (Q) determination of the nature and magnitude of the speed instability associated with the backside of the thrust required curve; (2) confirmation of the validity of existing MIL-SPEC handling qualities criteria; (3) safety of operation of the vehicle in the event of autothrottle failure; and (4) correlation of required engine responsiveness with level of speed instability. Preliminary findings comprise the following: (1) The critical velocity for speed instability was determined to be 196 knots, well above the projected approach speed of 155 knots. This puts the vehicle far on the backside of its thrust required curve. While the aircraft can be configured to have static and dynamic stability at this trim point, a significant speed instability emerges, if a pilot or autopilot attempts flight path control with elevator and/or canard control surfaces only. This requires a properly configured autothrottle and/or variable aerodynamic drag devices which can provide speed stability; (2) An AST 105 type vehicle meets MIL-SPEC criteria only in part. While the damping criteria for phugoid and short period motion are met easily, the AST 105 falls short of the required minimum short period frequency, meaning that the HSCT is too sluggish in pitch to meet the military criteria. Obviously the military specification do not consider a vehicle with such high pitch inertia. With regard to speed stability and flight path stability criteria, the vehicle meets levels 2 and 3 of the military requirements, indicating that it would be landed safety with manual controls in case of an autothrottle failure, even though the pilot workload would be high; and (3) This requires

  6. Wind resource quality affected by high levels of renewables

    DOE PAGESBeta

    Diakov, Victor

    2015-06-17

    For solar photovoltaic (PV) and wind resources, the capacity factor is an important parameter describing the quality of the resource. As the share of variable renewable resources (such as PV and wind) on the electric system is increasing, so does curtailment (and the fraction of time when it cannot be avoided). At high levels of renewable generation, curtailments effectively change the practical measure of resource quality from capacity factor to the incremental capacity factor. The latter accounts only for generation during hours of no curtailment and is directly connected with the marginal capital cost of renewable generators for a givenmore » level of renewable generation during the year. The Western U.S. wind generation is analyzed hourly for a system with 75% of annual generation from wind, and it is found that the value for the system of resources with equal capacity factors can vary by a factor of 2, which highlights the importance of using the incremental capacity factor instead. Finally, the effect is expected to be more pronounced in smaller geographic areas (or when transmission limitations imposed) and less pronounced at lower levels of renewable energy in the system with less curtailment.« less

  7. Determination of saffron quality by high-performance liquid chromatography.

    PubMed

    Valle García-Rodríguez, M; Serrano-Díaz, Jéssica; Tarantilis, Petros A; López-Córcoles, Horacio; Carmona, Manuel; Alonso, Gonzalo L

    2014-08-13

    The aim of this work was to propose a high-performance liquid chromatography with diode array detection (HPLC-DAD) method for determining the three main compounds responsible for determining the quality of saffron (crocetin esters, picrocrocin, and safranal) by preparing an aqueous extract according to the ISO 3632 standard to solve the difficulty that this standard has for aroma and taste determination by ultraviolet-visible spectroscopy. Toward this aim, laboratory-isolated picrocrocin, a safranal standard with a purity of ≥ 88%, trans-crocetin di(β-D-gentiobiosyl) ester (trans-4-GG) and trans-crocetin (β-D-glucosyl)-(β-D-gentiobiosyl) ester (trans-3-Gg) standards, both with a purity of ≥ 99%, and 50 different saffron spice samples from Italy, Iran, Greece, and Spain were used in the intralaboratory validation of the HPLC method. The analytical method proposed was adequate in terms of linearity, selectivity, sensitivity, and accuracy for determining the three foremost parameters that define the quality of saffron using only a saffron solution prepared according to the ISO 3632 standard. PMID:25075549

  8. Wind resource quality affected by high levels of renewables

    SciTech Connect

    Diakov, Victor

    2015-06-17

    For solar photovoltaic (PV) and wind resources, the capacity factor is an important parameter describing the quality of the resource. As the share of variable renewable resources (such as PV and wind) on the electric system is increasing, so does curtailment (and the fraction of time when it cannot be avoided). At high levels of renewable generation, curtailments effectively change the practical measure of resource quality from capacity factor to the incremental capacity factor. The latter accounts only for generation during hours of no curtailment and is directly connected with the marginal capital cost of renewable generators for a given level of renewable generation during the year. The Western U.S. wind generation is analyzed hourly for a system with 75% of annual generation from wind, and it is found that the value for the system of resources with equal capacity factors can vary by a factor of 2, which highlights the importance of using the incremental capacity factor instead. Finally, the effect is expected to be more pronounced in smaller geographic areas (or when transmission limitations imposed) and less pronounced at lower levels of renewable energy in the system with less curtailment.

  9. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-11-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  10. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    PubMed

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  11. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    PubMed Central

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  12. Surgery at High-Quality Hospitals a Money-Saver for Medicare

    MedlinePlus

    ... gov/news/fullstory_160864.html Surgery at High-Quality Hospitals a Money-Saver for Medicare Savings is ... HealthDay News) -- Having major surgery at a high-quality hospital costs Medicare less than the same procedure ...

  13. High-sensitivity dilatometer for quality-control use

    NASA Astrophysics Data System (ADS)

    Tomer, G. S.; Schlegel, G. L.; Gaal, P. S.

    1988-03-01

    A simple-to-operate dilatometer, intended for rapid quality-control testing of low-expansion materials in a single temperature interval, is described. The instrument employs a thermoelectric heat/cool element to supply the thermal environment for the sample and a high-sensitivity linear variable differential transformer (LVDT) for displacement measurement. The mechanical configuration is made so as to eliminate the need for quartz correction and to provide a 4∶1 mechanical advantage to the displacement signal for improved accuracy. Operating between 0 and 100°C, the machine proved to give consistently good results with materials having expansion coefficients as low as 0.5×10-6 °C-1. Representative data on some carbonaceous materials and fused silica (quartz) are given.

  14. (Collection of high quality acoustical records for honeybees)

    SciTech Connect

    Kerr, H.T.; Buchanan, M.E.

    1987-02-19

    High quality acoustical data records were collected for both European and Africanized honeybees under various field conditions. This data base was needed for more rigorous evaluation of a honeybee identification technique previously developed by the travelers from preliminary data sets. Laboratory-grade recording equipment was used to record sounds made by honeybees in and near their nests and during foraging flights. Recordings were obtained from European and Africanized honeybees in the same general environment. Preliminary analyses of the acoustical data base clearly support the general identification algorithm: Africanized honeybee noise has significantly higher frequency content than does European honeybee noise. As this algorithm is refined, it may result in the development of a simple field-portable device for identifying subspecies of honeybees. Further, the honeybee's acoustical signals appear to be correlated with specific colony conditions. Understanding these variations may have enormous benefit for entomologists and for the beekeeping industry.

  15. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2002-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  16. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2005-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  17. Sequential interactive evolution for finding high-quality topologies

    NASA Astrophysics Data System (ADS)

    Avigad, Gideon; Salomon, Shaul; Knopf, George

    2015-10-01

    Finding a diverse set of high-quality (HQ) topologies for a single-objective optimization problem using an evolutionary computation algorithm can be difficult without a reliable measure that adequately describes the dissimilarity between competing topologies. In this article, a new approach for enhancing diversity among HQ topologies for engineering design applications is proposed. The technique initially selects one HQ solution and then searches for alternative HQ solutions by performing an optimization of the original objective and its dissimilarity with respect to the previously found solution. The proposed multi-objective optimization approach interactively amalgamates user articulated preferences with an evolutionary search so as sequentially to produce a set of diverse HQ solutions to a single-objective problem. For enhancing diversity, a new measure is suggested and an approach to reducing its computational time is studied and implemented. To illustrate the technique, a series of studies involving different topologies represented as bitmaps is presented.

  18. Proposal for efficient mode converter based on cavity quantum electrodynamics dark mode in a semiconductor quantum dot coupled to a bimodal microcavity

    NASA Astrophysics Data System (ADS)

    Li, Jiahua; Yu, Rong; Ma, Jinyong; Wu, Ying

    2014-10-01

    The ability to engineer and convert photons between different modes in a solid-state approach has extensive technological implications not only for classical communication systems but also for future quantum networks. In this paper, we put forward a scheme for coherent mode conversion of optical photons by utilizing the intermediate coupling between a single quantum dot and a bimodal photonic crystal microcavity via a waveguide. Here, one mode of the photonic crystal microcavity is coherently driven by an external single-frequency continuous-wave laser field and the two cavity modes are not coupled to each other due to their orthogonal polarizations. The undriven cavity mode is thus not directly coupled to the input driving laser and the only way it can get light is via the quantum dot. The influences of the system parameters on the photon-conversion efficiency are analyzed in detail in the limit of weak probe field and it is found that high photon-conversion efficiency can be achieved under appropriate conditions. It is shown that the cavity dark mode, which is a superposition of the two optical modes and is decoupled from the quantum dot, can appear in such a hybrid optical system. We discuss the properties of the dark mode and indicate that the formation of the dark mode enables the efficient transfer of optical fields between the two cavity modes.

  19. Proposal for efficient mode converter based on cavity quantum electrodynamics dark mode in a semiconductor quantum dot coupled to a bimodal microcavity

    SciTech Connect

    Li, Jiahua; Yu, Rong; Ma, Jinyong; Wu, Ying

    2014-10-28

    The ability to engineer and convert photons between different modes in a solid-state approach has extensive technological implications not only for classical communication systems but also for future quantum networks. In this paper, we put forward a scheme for coherent mode conversion of optical photons by utilizing the intermediate coupling between a single quantum dot and a bimodal photonic crystal microcavity via a waveguide. Here, one mode of the photonic crystal microcavity is coherently driven by an external single-frequency continuous-wave laser field and the two cavity modes are not coupled to each other due to their orthogonal polarizations. The undriven cavity mode is thus not directly coupled to the input driving laser and the only way it can get light is via the quantum dot. The influences of the system parameters on the photon-conversion efficiency are analyzed in detail in the limit of weak probe field and it is found that high photon-conversion efficiency can be achieved under appropriate conditions. It is shown that the cavity dark mode, which is a superposition of the two optical modes and is decoupled from the quantum dot, can appear in such a hybrid optical system. We discuss the properties of the dark mode and indicate that the formation of the dark mode enables the efficient transfer of optical fields between the two cavity modes.

  20. A high throughput DNA extraction method with high yield and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Preparation of large quantity and high quality genomic DNA from a large number of plant samples is a major bottleneck for most genetic and genomic analyses, such as, genetic mapping, TILLING (Targeting Induced Local Lesion IN Genome), and next-generation sequencing directly from sheared ...

  1. High Resolution Projection of Future Air Quality in South Asia

    NASA Astrophysics Data System (ADS)

    Kumar, R.; Barth, M. C.; Pfister, G.; Lamarque, J. F.; Walters, S.; Naja, M. K.; Ghude, S. D.

    2015-12-01

    About one seventh of the world's population living in South Asia faces the risk of severe air pollution due to high anthropogenic emissions of air pollutants. Recent studies have shown that exposure to present day air pollution in South Asia is sufficient enough to reduce the lifespan of about 660 million people by about 3 years, destroy food that can feed about 94 million poor people and cause economic loss of several billion dollars. This problem may worsen in the future as anthropogenic emissions are expected to increase due to rapid economic growth in South Asia, and climate change is expected to lead to atmospheric conditions conducive for the production and accumulation of air pollutants. In order to predict how air quality will change in South Asia in future (2050), we are conducting high resolution air quality simulations for the present day (2005-2014) and future (2046-2055) time periods using the Nested Regional Climate Model coupled with Chemistry (NRCM-Chem). The model domain covers entire South Asia at a horizontal grid spacing of 60 km with a nested domain over the densely populated and polluted Indo-Gangetic Plain region at a horizontal grid spacing of 12 km. The model results are being evaluated with available in situ and satellite based observations and the evaluation results show that NRCM-Chem model is able to capture several important features of the observed spatial and temporal distribution of key meteorological parameters and air pollutants. Initial model results show that annual average surface ozone and PM2.5 concentrations may increase by up to 15 ppbv and 25 μg m-3, respectively with highest increase in the Indo-Gangetic Plain.

  2. High-frequency and high-quality silicon carbide optomechanical microresonators

    PubMed Central

    Lu, Xiyuan; Lee, Jonathan Y.; Lin, Qiang

    2015-01-01

    Silicon carbide (SiC) exhibits excellent material properties attractive for broad applications. We demonstrate the first SiC optomechanical microresonators that integrate high mechanical frequency, high mechanical quality, and high optical quality into a single device. The radial-breathing mechanical mode has a mechanical frequency up to 1.69 GHz with a mechanical Q around 5500 in atmosphere, which corresponds to a fm · Qm product as high as 9.47 × 1012 Hz. The strong optomechanical coupling allows us to efficiently excite and probe the coherent mechanical oscillation by optical waves. The demonstrated devices, in combination with the superior thermal property, chemical inertness, and defect characteristics of SiC, show great potential for applications in metrology, sensing, and quantum photonics, particularly in harsh environments that are challenging for other device platforms. PMID:26585637

  3. High-frequency and high-quality silicon carbide optomechanical microresonators.

    PubMed

    Lu, Xiyuan; Lee, Jonathan Y; Lin, Qiang

    2015-01-01

    Silicon carbide (SiC) exhibits excellent material properties attractive for broad applications. We demonstrate the first SiC optomechanical microresonators that integrate high mechanical frequency, high mechanical quality, and high optical quality into a single device. The radial-breathing mechanical mode has a mechanical frequency up to 1.69 GHz with a mechanical Q around 5500 in atmosphere, which corresponds to a fm · Qm product as high as 9.47 × 10(12) Hz. The strong optomechanical coupling allows us to efficiently excite and probe the coherent mechanical oscillation by optical waves. The demonstrated devices, in combination with the superior thermal property, chemical inertness, and defect characteristics of SiC, show great potential for applications in metrology, sensing, and quantum photonics, particularly in harsh environments that are challenging for other device platforms. PMID:26585637

  4. Solvent-free enzymatic production of high quality cetyl esters.

    PubMed

    Serrano-Arnaldos, Mar; Máximo-Martín, María Fuensanta; Montiel-Morte, María Claudia; Ortega-Requena, Salvadora; Gómez-Gómez, Elisa; Bastida-Rodríguez, Josefa

    2016-04-01

    A solvent-free biocatalytic process for the synthesis of high quality cetyl laurate, myristate, palmitate and stearate has been optimized. This enzymatic procedure follows the fundamental principles of the Green Chemistry and lead to sustainable products, which can be labeled as natural and conform to the principal requirements for its use in high value-added goods. The four esters selected are the main components of spermaceti, a mixture of waxes very appreciated in cosmetic and pharmacy because of its physical properties and emolliency, which was formerly extracted from the head of the sperm whales. In this paper, the influence of the amount of biocatalyst, the commercially available Novozym(®) 435, and the temperature were studied in an open-air batch reactor before carrying out the synthesis in a high performance vacuum reactor with dry nitrogen input to shift the equilibrium towards product formation. Under optimal conditions, conversion was higher than 98.5 %. The characterization of the enzymatic cetyl esters puts in evidence that these are ultra-pure compounds, which have similar properties to the ones obtained through the conventional industrial processes with the extra benefit of being environmentally friendly. PMID:26801670

  5. Which Combination of High Quality Infant-Toddler and Preschool Care Best Promotes School Readiness?

    ERIC Educational Resources Information Center

    Li, Weilin; Farkas, George; Duncan, Greg J.; Burchinal, Margaret R.; Vandell, Deborah L.; Ruzek, Erik A.; Dang, Tran T.

    2011-01-01

    This paper aims to test the following hypotheses: Hypothesis 1 (H1): Everything else the same, high quality infant-toddler care will increase children's cognitive scores immediately (i.e. at 24 months of age). However, without subsequent high quality preschool, children with high quality infant-toddler care will not have higher cognitive and…

  6. Criteria for High Quality Biology Teaching: An Analysis

    ERIC Educational Resources Information Center

    Tasci, Guntay

    2015-01-01

    This study aims to analyze the process under which biology lessons are taught in terms of teaching quality criteria (TQC). Teaching quality is defined as the properties of efficient teaching and is considered to be the criteria used to measure teaching quality both in general and specific to a field. The data were collected through classroom…

  7. Low-quality birds do not display high-quality signals: The cysteine-pheomelanin mechanism of honesty.

    PubMed

    Galván, Ismael; Wakamatsu, Kazumasa; Camarero, Pablo R; Mateo, Rafael; Alonso-Alvarez, Carlos

    2015-01-01

    The mechanisms that make that the costs of producing high-quality signals are unaffordable to low-quality signalers are a current issue in animal communication. The size of the melanin-based bib of male house sparrows Passer domesticus honestly signals quality. We induced the development of new bibs while treating males with buthionine-sulfoximine (BSO), a substance that depletes the levels of the antioxidant glutathione (GSH) and the amino acid cysteine, two elements that switch melanogenesis from eumelanin to pheomelanin. Final bib size is negatively related to pheomelanin levels in the bib feathers. BSO reduced cysteine and GSH levels in all birds, but improved phenotypes (bibs larger than controls) were only expressed by high-quality birds (BSO birds with largest bibs initially). Negative associations between final bib size and cysteine levels in erythrocytes, and between pheomelanin and cysteine levels, were observed in high-quality birds only. These findings suggest that a mechanism uncoupling pheomelanin and cysteine levels may have evolved in low-quality birds to avoid producing bibs of size not corresponding to their quality and greater relative costs. Indeed, greater oxidative stress in cells was not observed in low-quality birds. This may represent the first mechanism maintaining signal honesty without producing greater relative costs on low-quality signalers. PMID:25330349

  8. Low-quality birds do not display high-quality signals: The cysteine-pheomelanin mechanism of honesty

    PubMed Central

    Galván, Ismael; Wakamatsu, Kazumasa; Camarero, Pablo R; Mateo, Rafael; Alonso-Alvarez, Carlos

    2015-01-01

    The mechanisms that make that the costs of producing high-quality signals are unaffordable to low-quality signalers are a current issue in animal communication. The size of the melanin-based bib of male house sparrows Passer domesticus honestly signals quality. We induced the development of new bibs while treating males with buthionine-sulfoximine (BSO), a substance that depletes the levels of the antioxidant glutathione (GSH) and the amino acid cysteine, two elements that switch melanogenesis from eumelanin to pheomelanin. Final bib size is negatively related to pheomelanin levels in the bib feathers. BSO reduced cysteine and GSH levels in all birds, but improved phenotypes (bibs larger than controls) were only expressed by high-quality birds (BSO birds with largest bibs initially). Negative associations between final bib size and cysteine levels in erythrocytes, and between pheomelanin and cysteine levels, were observed in high-quality birds only. These findings suggest that a mechanism uncoupling pheomelanin and cysteine levels may have evolved in low-quality birds to avoid producing bibs of size not corresponding to their quality and greater relative costs. Indeed, greater oxidative stress in cells was not observed in low-quality birds. This may represent the first mechanism maintaining signal honesty without producing greater relative costs on low-quality signalers. PMID:25330349

  9. Coexisting localized and extended optical Bloch states in a periodic deep wire array microcavity

    NASA Astrophysics Data System (ADS)

    Löchner, Franz J. F.; Mischok, Andreas; Brückner, Robert; Lyssenko, Vadim G.; Zakhidov, Alexander A.; Fröb, Hartmut; Leo, K.

    2015-09-01

    We embed periodic SiO2 wires in an organic microcavity, producing a rectangular potential by the different optical thicknesses of the active layer due to the additional SiO2 layer. By μ -photoluminescence spectroscopy, we observe the energy dispersion of the photons and obtain discrete localized below and extended Bloch states above the potential barrier, respectively, showing that electro-magnetic waves can behave like massive particles, such as electrons, in crystal lattices. We investigate the dependencies on wire width and period and use the Kronig-Penney model to describe the photon energy dispersion, including an "effective mass" of a photon propagating through a microcavity implying polarization splitting. We obtain excellent agreement between experiment, simulation and analytical calculation.

  10. Polariton condensation in a strain-compensated planar microcavity with InGaAs quantum wells

    SciTech Connect

    Cilibrizzi, Pasquale; Askitopoulos, Alexis Silva, Matteo; Lagoudakis, Pavlos G.; Bastiman, Faebian; Clarke, Edmund; Zajac, Joanna M.; Langbein, Wolfgang

    2014-11-10

    The investigation of intrinsic interactions in polariton condensates is currently limited by the photonic disorder of semiconductor microcavity structures. Here, we use a strain compensated planar GaAs/AlAs{sub 0.98}P{sub 0.02} microcavity with embedded InGaAs quantum wells having a reduced cross-hatch disorder to overcome this issue. Using real and reciprocal space spectroscopic imaging under non-resonant optical excitation, we observe polariton condensation and a second threshold marking the onset of photon lasing, i.e., the transition from the strong to the weak-coupling regime. Condensation in a structure with suppressed photonic disorder is a necessary step towards the implementation of periodic lattices of interacting condensates, providing a platform for on chip quantum simulations.

  11. Localized Surface Plasmons Selectively Coupled to Resonant Light in Tubular Microcavities.

    PubMed

    Yin, Yin; Li, Shilong; Böttner, Stefan; Yuan, Feifei; Giudicatti, Silvia; Saei Ghareh Naz, Ehsan; Ma, Libo; Schmidt, Oliver G

    2016-06-24

    Vertical gold nanogaps are created on microtubular cavities to explore the coupling between resonant light supported by the microcavities and surface plasmons localized at the nanogaps. Selective coupling of optical axial modes and localized surface plasmons critically depends on the exact location of the gold nanogap on the microcavities, which is conveniently achieved by rolling up specially designed thin dielectric films into three-dimensional microtube cavities. The coupling phenomenon is explained by a modified quasipotential model based on perturbation theory. Our work reveals the coupling of surface plasmon resonances localized at the nanoscale to optical resonances confined in microtubular cavities at the microscale, implying a promising strategy for the investigation of light-matter interactions. PMID:27391725

  12. Giant Up-Conversion Efficiency of InGaAs Quantum Dots in a Planar Microcavity

    PubMed Central

    Xu, Qinfeng; Piermarocchi, Carlo; Pershin, Yuriy V.; Salamo, G. J.; Xiao, Min; Wang, Xiaoyong; Shih, Chih-Kang

    2014-01-01

    Self-assembled InGaAs quantum dots (QDs) were fabricated inside a planar microcavity with two vertical cavity modes. This allowed us to excite the QDs coupled to one of the vertical cavity modes through two propagating cavity modes to study their down- and up-converted photoluminescence (PL). The up-converted PL increased continuously with the increasing temperature, reaching an intensity level comparable to that of the down-converted PL at ~120 K. This giant efficiency in the up-converted PL of InGaAs QDs was enhanced by about 2 orders of magnitude with respect to a similar structure without cavity. We tentatively explain the enhanced up-converted signal as a direct consequence of the modified spontaneous emission properties of the QDs in the microcavity, combined with the phonon absorption and emission effects. PMID:24492329

  13. Optically tunable microcavity in a planar photonic crystal silicon waveguide buried in oxide.

    PubMed

    Märki, Iwan; Salt, Martin; Herzig, Hans Peter; Stanley, Ross; El Melhaoui, L; Lyan, P; Fedeli, J M

    2006-02-15

    We present all-optical tuning and switching of a microcavity inside a two-dimensional photonic crystal waveguide. The photonic crystal structure is fabricated in silicon-on-insulator using complementary metal-oxide semiconductor processing techniques based on deep ultraviolet lithography and is completely buried in a silicon dioxide cladding that provides protection from the environment. By focusing a laser onto the microcavity region, both a thermal and a plasma dispersion effect are generated, allowing tuning and fast modulation of the in-plane transmission. By means of the temporal characteristics of the in-plane transmission, we experimentally identify a slower thermal and a fast plasma dispersion effect with modulation bandwidths of the order of several 100 kHz and up to the gigahertz level, respectively. PMID:16496904

  14. Localized Surface Plasmons Selectively Coupled to Resonant Light in Tubular Microcavities

    NASA Astrophysics Data System (ADS)

    Yin, Yin; Li, Shilong; Böttner, Stefan; Yuan, Feifei; Giudicatti, Silvia; Saei Ghareh Naz, Ehsan; Ma, Libo; Schmidt, Oliver G.

    2016-06-01

    Vertical gold nanogaps are created on microtubular cavities to explore the coupling between resonant light supported by the microcavities and surface plasmons localized at the nanogaps. Selective coupling of optical axial modes and localized surface plasmons critically depends on the exact location of the gold nanogap on the microcavities, which is conveniently achieved by rolling up specially designed thin dielectric films into three-dimensional microtube cavities. The coupling phenomenon is explained by a modified quasipotential model based on perturbation theory. Our work reveals the coupling of surface plasmon resonances localized at the nanoscale to optical resonances confined in microtubular cavities at the microscale, implying a promising strategy for the investigation of light-matter interactions.

  15. Effect of high pressure-high temperature process on meat product quality

    NASA Astrophysics Data System (ADS)

    Duranton, Frédérique; Marée, Elvire; Simonin, Hélène; Chéret, Romuald; de Lamballerie, Marie

    2011-03-01

    High pressure/high temperature (HPHT) processing is an innovative way to sterilize food and has been proposed as an alternative to conventional retorting. By using elevated temperatures and adiabatic compression, it allows the inactivation of vegetative microorganisms and pathogen spores. Even though the microbial inactivation has been widely studied, the effect of such process on sensorial attributes of food products, especially meat products, remains rare. The aim of this study was to investigate the potential of using HPHT process (500 MPa/115 °C) instead of conventional retorting to stabilize Toulouse sausages while retaining high organoleptic quality. The measurements of texture, color, water-holding capacity and microbial stability were investigated. It was possible to manufacture stable products at 500 MPa/115 °C/30 min. However, in these conditions, no improvement of the quality was found compared with conventional retorting.

  16. Plasmonic CROWs for Tunable Dispersion and High Quality Cavity Modes

    PubMed Central

    Wood, John J.; Lafone, Lucas; Hamm, Joachim M.; Hess, Ortwin; Oulton, Rupert F.

    2015-01-01

    Coupled resonator optical waveguides (CROWs) have the potential to revolutionise integrated optics, to slow-light and enhance linear and non-linear optical phenomena. Here we exploit the broad resonances and subwavelength nature of localized surface plasmons in a compact CROW design where plasmonic nanoparticles are side coupled to a dielectric waveguide. The plasmonic CROW features a low loss central mode with a highly tunable dispersion, that avoids coupling to the plasmonic nanoparticles close to the band-edge. We show that this low loss character is preserved in finite plasmonic CROWs giving rise to Fabry-Perot type resonances that have high quality factors of many thousands, limited only by the CROW length. Furthermore we demonstrate that the proposed CROW design is surprisingly robust to disorder. By varying the geometric parameters one can not only reduce the losses into dissipative or radiative channels but also control the outcoupling of energy to the waveguide. The ability to minimise loss in plasmonic CROWs while maintaining dispersion provides an effective cavity design for chip-integrated laser devices and applications in linear and non-linear nano-photonics. PMID:26631579

  17. High-Quality Seismic Observations of Sonic Booms

    NASA Astrophysics Data System (ADS)

    Wurman, G.; Haering, E. A.; Price, M.

    2011-12-01

    The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on Earthquake Warning Systems in order to prevent such systems from experiencing false alarms due to sonic booms. The airspace above the Antelope Valley, California includes the High Altitude Supersonic Corridor and the Black Mountain Supersonic Corridor. These corridors are among the few places in the US where supersonic flight is permitted, and sonic booms are commonplace in the Antelope Valley. One result of this project is a rich dataset of high-quality accelerometer records of sonic booms which can shed light on the interaction between these atmospheric phenomena and the solid earth. Nearly 100 sonic booms were recorded with low-noise triaxial MEMS accelerometers recording 1000 samples per second. The sonic booms had peak overpressures ranging up to approximately 10 psf and were recorded in three flight series in 2010 and 2011. Each boom was recorded with up to four accelerometers in various array configurations up to 100 meter baseline lengths, both in the built environment and the free field. All sonic booms were also recorded by nearby microphones. We present the results of the project in terms of the potential for sonic-boom-induced false alarms in Earthquake Warning Systems, and highlight some of the interesting features of the dataset.

  18. High-Quality Seismic Observations of Sonic Booms

    NASA Technical Reports Server (NTRS)

    Wurman, Gilead; Haering, Edward A., Jr.; Price, Michael J.

    2011-01-01

    The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on Earthquake Warning Systems in order to prevent such systems from experiencing false alarms due to sonic booms. The airspace above the Antelope Valley, California includes the High Altitude Supersonic Corridor and the Black Mountain Supersonic Corridor. These corridors are among the few places in the US where supersonic flight is permitted, and sonic booms are commonplace in the Antelope Valley. One result of this project is a rich dataset of high-quality accelerometer records of sonic booms which can shed light on the interaction between these atmospheric phenomena and the solid earth. Nearly 100 sonic booms were recorded with low-noise triaxial MEMS accelerometers recording 1000 samples per second. The sonic booms had peak overpressures ranging up to approximately 10 psf and were recorded in three flight series in 2010 and 2011. Each boom was recorded with up to four accelerometers in various array configurations up to 100 meter baseline lengths, both in the built environment and the free field. All sonic booms were also recorded by nearby microphones. We present the results of the project in terms of the potential for sonic-boom-induced false alarms in Earthquake Warning Systems, and highlight some of the interesting features of the dataset.

  19. High-quality remote interactive imaging in the operating theatre

    NASA Astrophysics Data System (ADS)

    Grimstead, Ian J.; Avis, Nick J.; Evans, Peter L.; Bocca, Alan

    2009-02-01

    We present a high-quality display system that enables the remote access within an operating theatre of high-end medical imaging and surgical planning software. Currently, surgeons often use printouts from such software for reference during surgery; our system enables surgeons to access and review patient data in a sterile environment, viewing real-time renderings of MRI & CT data as required. Once calibrated, our system displays shades of grey in Operating Room lighting conditions (removing any gamma correction artefacts). Our system does not require any expensive display hardware, is unobtrusive to the remote workstation and works with any application without requiring additional software licenses. To extend the native 256 levels of grey supported by a standard LCD monitor, we have used the concept of "PseudoGrey" where slightly off-white shades of grey are used to extend the intensity range from 256 to 1,785 shades of grey. Remote access is facilitated by a customized version of UltraVNC, which corrects remote shades of grey for display in the Operating Room. The system is successfully deployed at Morriston Hospital, Swansea, UK, and is in daily use during Maxillofacial surgery. More formal user trials and quantitative assessments are being planned for the future.

  20. Fabrication of a three-dimensional nanoporous polymer film as a diffuser for microcavity OLEDs

    NASA Astrophysics Data System (ADS)

    Pyo, Beom; Cho, Ye Ram; Suh, Min Chul

    2015-09-01

    We used a nanoporous polymer film prepared by cellulose acetate butyrate with ~40% of optical haze value as a diffuser. It was fabricated by a simple spin-coating process during continuous water mist supply by a humidifier. The pores were created by the elastic bouncing mechanism (rather than the thermocapillary convection mechanism) of the supplied water droplets. The shapes and sizes of the caves formed near the polymer surface are randomly distributed, with a relatively narrow pore size distribution (300-500 nm). Specifically, we focused on controlling the surface morphology to give a three-dimensional (3D) multi-stacked nanocave structure because we had already learnt that two-dimensional nanoporous structures showed serious loss of luminance in the forward direction. Using this approach, we found that the 3D nanoporous polymer film can effectively reduce the viewing angle dependency of strong microcavity OLEDs without any considerable decrease in the total intensity of the out-coupled light. We applied this nanoporous polymer film to microcavity OLEDs to investigate the possibility of using it as a diffuser layer. The resulting nanoporous polymer film effectively reduced the viewing angle dependency of the microcavity OLEDs, although a pixel blurring phenomenon occurred. Despite its negative effects, such as the drop in efficiency in the forward direction and the pixel blurring, the introduction of a nanoporous polymer film as a scattering medium on the back side of the glass substrate eliminated the viewing angle dependency. Thus, this approach is a promising method to overcome the serious drawbacks of microcavity OLEDs.

  1. Entanglement purification based on hybrid entangled state using quantum-dot and microcavity coupled system.

    PubMed

    Wang, Chuan; Zhang, Yong; Zhang, Ru

    2011-12-01

    We theoretically investigate an entanglement purification protocol with photon and electron hybrid entangled state resorting to quantum-dot spin and microcavity coupled system. The present system is used to construct the parity check gate which allows a quantum non-demolition measurement on the spin parity. The cavity-spin coupled system provides a novel experimental platform of quantum information processing with photon and solid qubit. PMID:22273961

  2. Spin wave localization in one-dimensional magnonic microcavity comprising yttrium iron garnet

    SciTech Connect

    Kanazawa, Naoki; Goto, Taichi Inoue, Mitsuteru

    2014-08-28

    We demonstrate the localization of magnetostatic surface waves, i.e., spin waves, in a one-dimensional magnonic microcavity substantialized with periodical conductivity modulation. The narrow localized state is observed inside band gaps and is responsible for a sharp transmission peak. The experimental results strongly agree with the theoretical prediction made with the shape magnetic anisotropy of the propagating medium composed of yttrium iron garnet taken into account.

  3. Realization of Plasmonic Microcavity with Full Transverse and Longitudinal Mode Selection

    PubMed Central

    Liu, Ju; Chen, Yue-Gang; Gan, Lin; Xiao, Ting-Hui; Li, Zhi-Yuan

    2016-01-01

    Surface plasmon polaritons (SPPs) manipulation is of vital importance to construct ultracompact integrated micro/nano-optical devices and systems. Here we report the design, fabrication, and characterization of a SPP microcavity with full transverse and longitudinal mode selection and control on the surface of gold film. The designed microcavity supports the fundamental and first-order transverse modes of Gaussian mode beam with controllable longitudinal modes, respectively. The transverse mode is determined by two holographic mirrors made from deliberately designed groove patterns via the surface electromagnetic wave holography methodology, while the longitudinal mode is determined by the length of cavity. Both numerical simulations and leaky-wave SPP mode observations confirm the realization of full mode selection in the fabricated cavity. Our work opens up a powerful way to fully explore longitudinal and transverse mode control in SPP microcavities, which will be beneficial for light-matter interaction enhancement, construction of novel SPP nanolaser and microlaser, optical sensing, and optical information processing. PMID:27273163

  4. Phase sensitive properties and coherent manipulation of a photonic crystal microcavity.

    PubMed

    Quiring, Wadim; Jonas, Björn; Förstner, Jens; Rai, Ashish K; Reuter, Dirk; Wieck, Andreas D; Zrenner, Artur

    2016-09-01

    We present phase sensitive cavity field measurements on photonic crystal microcavities. The experiments have been performed as autocorrelation measurements with ps double pulse laser excitation for resonant and detuned conditions. Measured E-field autocorrelation functions reveal a very strong detuning dependence of the phase shift between laser and cavity field and of the autocorrelation amplitude of the cavity field. The fully resolved phase information allows for a precise frequency discrimination and hence for a precise measurement of the detuning between laser and cavity. The behavior of the autocorrelation amplitude and phase and their detuning dependence can be fully described by an analytic model. Furthermore, coherent control of the cavity field is demonstrated by tailored laser excitation with phase and amplitude controlled pulses. The experimental proof and verification of the above described phenomena became possible by an electric detection scheme, which employs planar photonic crystal microcavity photo diodes with metallic Schottky contacts in the defect region of the resonator. The applied photo current detection was shown to work also efficiently at room temperature, which make electrically contacted microcavities attractive for real world applications. PMID:27607671

  5. Formation and all-optical control of optical patterns in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Binder, R.; Tsang, C. Y.; Tse, Y. C.; Luk, M. H.; Kwong, N. H.; Chan, Chris K. P.; Leung, P. T.; Lewandowski, P.; Schumacher, Stefan; Lafont, O.; Baudin, E.; Tignon, J.

    2016-05-01

    Semiconductor microcavities offer a unique way to combine transient all-optical manipulation of GaAs quantum wells with the benefits of structural advantages of microcavities. In these systems, exciton-polaritons have dispersion relations with very small effective masses. This has enabled prominent effects, for example polaritonic Bose condensation, but it can also be exploited for the design of all-optical communication devices. The latter involves non-equilibrium phase transitions in the spatial arrangement of exciton-polaritons. We consider the case of optical pumping with normal incidence, yielding a spatially homogeneous distribution of exciton-polaritons in optical cavities containing the quantum wells. Exciton-exciton interactions can trigger instabilities if certain threshold behavior requirements are met. Such instabilities can lead, for example, to the spontaneous formation of hexagonal polariton lattices (corresponding to six-spot patterns in the far field), or to rolls (corresponding to two-spot far field patterns). The competition among these patterns can be controlled to a certain degree by applying control beams. In this paper, we summarize the theory of pattern formation and election in microcavities and illustrate the switching between patterns via simulation results.

  6. Realization of Plasmonic Microcavity with Full Transverse and Longitudinal Mode Selection.

    PubMed

    Liu, Ju; Chen, Yue-Gang; Gan, Lin; Xiao, Ting-Hui; Li, Zhi-Yuan

    2016-01-01

    Surface plasmon polaritons (SPPs) manipulation is of vital importance to construct ultracompact integrated micro/nano-optical devices and systems. Here we report the design, fabrication, and characterization of a SPP microcavity with full transverse and longitudinal mode selection and control on the surface of gold film. The designed microcavity supports the fundamental and first-order transverse modes of Gaussian mode beam with controllable longitudinal modes, respectively. The transverse mode is determined by two holographic mirrors made from deliberately designed groove patterns via the surface electromagnetic wave holography methodology, while the longitudinal mode is determined by the length of cavity. Both numerical simulations and leaky-wave SPP mode observations confirm the realization of full mode selection in the fabricated cavity. Our work opens up a powerful way to fully explore longitudinal and transverse mode control in SPP microcavities, which will be beneficial for light-matter interaction enhancement, construction of novel SPP nanolaser and microlaser, optical sensing, and optical information processing. PMID:27273163

  7. Valley-Polarized Exciton-Polaritons in a Monolayer Semiconductor Embedded in a Microcavity

    NASA Astrophysics Data System (ADS)

    Chen, Yen-J.; Stanev, Teodor K.; Stern, Nathaniel P.; Cain, Jeffrey D.; Dravid, Vinayak P.

    Two-dimensional transition metal dichalcogenides (TMDs) are semiconductors that exhibit degenerate, but inequivalent, valleys at their K-point band gaps which selectively couple to circularly-polarized light fields. Coherent hybrid states of light and matter, exciton-polaritons, have been observed when monolayer TMDs strongly interact with photon fields in a microcavity. The degree of polarization is determined by the relative rates of exciton and intervalley relaxation, which can be modified for microcavity exciton-polaritons. Preservation of valley-polarization in a microcavity at room temperature is compared to the nearly zero polarization for bare monolayer MoS2 on SiO2, demonstrating cavity-modified relaxation dynamics of the coherent valley-specific exciton-polaritons. These results suggest promising opto-electronic applications for valley-based polaritonic and photonic devices integrating monolayer TMDs. This work is supported by the U.S. Department of Energy (BES DE-SC0012130) and the National Science Foundation MRSEC program (DMR-1121262). N.P.S. is an Alfred P. Sloan Research Fellow.

  8. High Quality 3D data capture from UAV imagery

    NASA Astrophysics Data System (ADS)

    Haala, Norbert; Cramer, Michael; Rothermel, Mathias

    2014-05-01

    The flexible use of unmanned airborne systems is especially beneficial while aiming at data capture for geodetic-photogrammetric applications within areas of limited extent. This can include tasks like topographical mapping in the context of land management and consolidation or natural hazard mapping for the documentation of landslide areas. Our presentation discusses the suitability of UAV-systems for such tasks based on a pilot project for the Landesamt für Geoinformation und Landentwicklung Baden-Württemberg (LGL BW). This study evaluated the efficiency and accuracy of photogrammetric image collection by UAV-systems for demands of national mapping authorities. For this purpose the use of different UAV platforms and cameras for the generation of photogrammetric standard products like ortho images and digital surface models were evaluated. However, main focus of the presentation is the investigation of the quality potential of UAV-based 3D data capture at high resolution and accuracies. This is exemplary evaluated by the documentation of a small size (700x350m2) landslide area by a UAV flight. For this purpose the UAV images were used to generate 3D point clouds at a resolution of 5-8cm, which corresponds to the ground sampling distance GSD of the original images. This was realized by dense, pixel-wise matching algorithms both available in off-the-shelf and research software tools. Suitable results can especially be derived if large redundancy is available from highly overlapping image blocks. Since UAV images can be collected easily at a high overlap due to their low cruising speed. Thus, our investigations clearly demonstrated the feasibility of relatively simple UAV-platforms and cameras for 3D point determination close to the sub-pixel level.

  9. Systems and processes that ensure high quality care.

    PubMed

    Bassett, Sally; Westmore, Kathryn

    2012-10-01

    This is the second in a series of articles examining the components of good corporate governance. It considers how the structures and processes for quality governance can affect an organisation's ability to be assured about the quality of care. Complex information systems and procedures can lead to poor quality care, but sound structures and processes alone are insufficient to ensure good governance, and behavioural factors play a significant part in making sure that staff are enabled to provide good quality care. The next article in this series looks at how the information reporting of an organisation can affect its governance. PMID:23252087

  10. Tunable high quality factor in two multimode plasmonic stubs waveguide

    PubMed Central

    Chen, Zhiquan; Li, Hongjian; Zhan, Shiping; Li, Boxun; He, Zhihui; Xu, Hui; Zheng, Mingfei

    2016-01-01

    We numerically investigate the optical characteristics of a metal-dielectric-metal (MDM) waveguide side-coupled with two identical multimode stub resonators. Double plasmon-induced transparency (PIT) peaks with narrow full width at half maximum (FWHM) and high quality factor (Q-factor) can be observed in this structure. The Q-factors of PIT peaks in two stub resonators system are larger than those in single stub resonator system. A multimode coupled-radiation oscillator theory (MC-ROT), which is derived from ROT, is proposed to analyze the spectral response in the multimode system for the first time. The analytical results are confirmed by the finite-difference time-domain (FDTD) simulation results. We can also find that the Q-factors of the two PIT peaks have an opposite evolution tendency with the change of the stubs parameters and the maximum can reach to 427. These results may provide some applications for ultrasensitive sensors, switches and efficient filters. PMID:27075935

  11. Semiconductor nano-gap antennas with high quality factor

    NASA Astrophysics Data System (ADS)

    Uemoto, Mitsuharu; Ajiki, Hiroshi

    2013-03-01

    Metallic islands with nano-gap structure are one of the most popular optical antennas. We theoretically propose a new nano-gap antenna utilizing exciton resonance of semiconductor. A light field at the nano-gap (hot spot) formed between two CuCl islands is significantly enhanced by a factor of metallic antennas. However, the hot spot of the semiconducting antenna exhibits much higher quality factor (Q ~104) at T = 40 K than those of metallic antennas which do not exceed Q ~ 100 . Our result suggests the semiconducting antenna would function as a new type of photonic cavity. The calculation method is based on a finite element method which can take into account exciton resonance. We also systematically study the geometry dependence of the enhancement factor and Q factor. In contrast to metallic antenna, blunt edges of semiconducting islands at the gap are preferable in order to achieve high enhancement factor. This is because of the fact that exciton wave function extends near the edge for blunt geometry.

  12. High quality ferromagnetic 0 and π Josephson tunnel junctions

    NASA Astrophysics Data System (ADS)

    Weides, M.; Kemmler, M.; Goldobin, E.; Koelle, D.; Kleiner, R.; Kohlstedt, H.; Buzdin, A.

    2006-09-01

    The authors fabricated high quality Nb /Al2O3/Ni0.6Cu0.4/Nb superconductor-insulatorferromagnet-superconductor Josephson tunnel junctions. Depending on the thickness of the ferromagnetic Ni0.6Cu0.4 layer and on the ambient temperature, the junctions were in the 0 or π ground state. All junctions have homogeneous interfaces showing almost perfect Fraunhofer patterns. The Al2O3 tunnel barrier allows one to achieve rather low damping, which is desired for many experiments especially in the quantum domain. The McCumber parameter βc increases exponentially with decreasing temperature and reaches βc≈700 at T =2.11K. The critical current density in the π state was up to 5A/cm2 at T =2.11K, resulting in a Josephson penetration depth λJ as low as 160μm. Experimentally determined junction parameters are well described by theory taking into account spin-flip scattering in the Ni0.6Cu0.4 layer and different transparencies of the interfaces.

  13. Tunable high quality factor in two multimode plasmonic stubs waveguide.

    PubMed

    Chen, Zhiquan; Li, Hongjian; Zhan, Shiping; Li, Boxun; He, Zhihui; Xu, Hui; Zheng, Mingfei

    2016-01-01

    We numerically investigate the optical characteristics of a metal-dielectric-metal (MDM) waveguide side-coupled with two identical multimode stub resonators. Double plasmon-induced transparency (PIT) peaks with narrow full width at half maximum (FWHM) and high quality factor (Q-factor) can be observed in this structure. The Q-factors of PIT peaks in two stub resonators system are larger than those in single stub resonator system. A multimode coupled-radiation oscillator theory (MC-ROT), which is derived from ROT, is proposed to analyze the spectral response in the multimode system for the first time. The analytical results are confirmed by the finite-difference time-domain (FDTD) simulation results. We can also find that the Q-factors of the two PIT peaks have an opposite evolution tendency with the change of the stubs parameters and the maximum can reach to 427. These results may provide some applications for ultrasensitive sensors, switches and efficient filters. PMID:27075935

  14. Characterization of non equilibrium effects on high quality critical flows

    SciTech Connect

    Camelo, E.; Lemonnier, H.; Ochterbeck, J.

    1995-09-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.

  15. Tunable high quality factor in two multimode plasmonic stubs waveguide

    NASA Astrophysics Data System (ADS)

    Chen, Zhiquan; Li, Hongjian; Zhan, Shiping; Li, Boxun; He, Zhihui; Xu, Hui; Zheng, Mingfei

    2016-04-01

    We numerically investigate the optical characteristics of a metal-dielectric-metal (MDM) waveguide side-coupled with two identical multimode stub resonators. Double plasmon-induced transparency (PIT) peaks with narrow full width at half maximum (FWHM) and high quality factor (Q-factor) can be observed in this structure. The Q-factors of PIT peaks in two stub resonators system are larger than those in single stub resonator system. A multimode coupled-radiation oscillator theory (MC-ROT), which is derived from ROT, is proposed to analyze the spectral response in the multimode system for the first time. The analytical results are confirmed by the finite-difference time-domain (FDTD) simulation results. We can also find that the Q-factors of the two PIT peaks have an opposite evolution tendency with the change of the stubs parameters and the maximum can reach to 427. These results may provide some applications for ultrasensitive sensors, switches and efficient filters.

  16. Evaluation of hybrid treatments to produce high quality reuse water.

    PubMed

    Luiz, D B; Silva, G S; Vaz, E A C; José, H J; Moreira, R F P M

    2011-01-01

    Four tertiary hybrid treatments to produce high quality reused water, fulfilling Brazilian drinking water regulations, from a slaughterhouse's secondary treated effluent were evaluated. The pilot plant with a capacity of 500 L h(-1) was set up and consisted of these stages: pre-filtration system (cartridge filter 50 micron, activated carbon filter, cartridge filter 10 micron), oxidation (H2O2) or second filtration (ceramic filter, UF) followed by UV radiation (90 L h(-1)). The best combination was T4: pre-filtration followed by H2O2 addition and UV radiation (AOP H2O2/UV). Disinfection kinetics by T4 followed pseudo first-order kinetics: k(T4) = 0.00943 s(-1) or 0.00101 cm2 mJ(-1). Three different zones (A, B, C) were observed in the UV254 degradation kinetics (pseudo-first order kinetics): k' decreased over time (k'(A) > k'(B) > k'(C)). PMID:21902048

  17. Quality controlled glacier inventory in high Asian mountains

    NASA Astrophysics Data System (ADS)

    Sakai, A.; Nuimura, T.; Taniguchi, K.; Lamsal, D.; Nagai, H.; Tsutaki, S.; Kozawa, A.; Hoshina, Y.; Takenaka, S.; Omiya, S.; Tsunematsu, K.; Tshering, P.; Fujita, K.; Okamoto, S.

    2013-12-01

    Glacier inventories provide a basic information for the water resources, glacier mass balance and ice volume at continental areas. Although glaciers in the Asian mountain are thought to play an important role for the regional water resources (Immerzeel et al., 2010), glacier distribution in the Asia have been poorly understood. Our GAMDAM (Glacier Area Mapping for Discharge in Asian Mountains) project have conducted to establish a glacier inventory with the aim of estimating glacier runoff contribution to river runoff. Our target region covers the High Mountain Asia, extending from 27 to 52 degrees N and from 68 to 104 degrees E. Glacier outlines were manually delineated using more than 260 of LANDSAT images taken from 1999 to 2003. Thermal infrared band was also used to delineate termini of debris-covered glaciers with help of high resolution images on Google Earth. The manual delineation has been conducted for more than two years by 5-7 operators. We conducted several tests, along which the operators delineated the same regions, and assessed the quality and criteria, and fed them back to the operators. At the end of June 2013, the inventory was completed 80% with about 63000 glaciers covering 7.8 × 10^4 km^2. Median elevation of glaciers has been interpreted as a proxy for the equilibrium line altitude (ELA), at which the accumulation and ablation were equal and thus the mass balance was zero (Braithwaite and Raper, 2009). Distribution of the median altitude derived from the GAMDAM glacier inventory was well consistent with that previously reported (Shi et al., 1980).

  18. Quality Assurance Roadmap for High Performance Residential Buildings

    SciTech Connect

    2008-10-05

    This report outlines the approach to quality assurance in the construction process for new residential construction, including seven process steps from the assessment of current construction practice, through design and documentation changes, to training and quality control for on-site personnel.

  19. Defining High Quality ECED Provision. A Note and an Exercise.

    ERIC Educational Resources Information Center

    Williams, Sian

    This paper examines quality in providing early childhood education and development (ECED) services and presents an exercise to guide critical reflection on quality in ECED provision. It maintains that there has been a shift away from the study of children as solitary learners to the study of children learning in a social context. This research…

  20. Strong coupling in non-polar GaN/AlGaN microcavities with air-gap/III-nitride distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Tao, Renchun; Arita, Munetaka; Kako, Satoshi; Kamide, Kenji; Arakawa, Yasuhiko

    2015-09-01

    Strong coupling between excitons and photons is experimentally demonstrated in m-plane GaN/AlGaN microcavities (MCs) with air/AlGaN distributed Bragg reflectors (DBRs) at room temperature. Strong coupling is confirmed by momentum space spectroscopy, and a Rabi splitting (Ω) of 84 meV is estimated. A Rabi splitting of 84 meV is the largest value reported in a III-nitride DBR MC to date and is mainly attributed to the shortened effective cavity length resulting from the high index contrast in the air-gap DBRs used here. These results show that III-nitride air-gap DBR MCs have a high potential for realizing high Ω / κ systems (where κ is the cavity loss).

  1. Analysis of high quality monatomic chromium films used in biological high resolution scanning electron microscopy.

    PubMed

    Apkarian, R P

    1994-01-01

    During the recent employment of field emission (FE) in-lens scanning electron microscopes (SEMs), refractory metal deposition technology has co-evolved to provide enhanced contrast of 1-10 nm hydrocarbon based biological structures imaged at high magnifications (> 200,000 times). Pioneer development employing the Penning sputter system in a high vacuum chamber proved that imaging of chromium (Cr) coated biological specimens contained enriched secondary electron (SE)-(I) contrasts. Single nanometer size fibrillar and particulate ectodomains within the context of complex biological membranes were accurately imaged without significant enlargement using the high resolution SE-I mode (HRSEM). This paper reports the transmission electron microscopy (TEM) testing of ultrathin (0.5-2.0 nm) Cr films deposited by planar magnetron sputter coating (PMSC). Essential parameters necessary to reproduce quality sputtered films of refractory metals used in HRSEM studies were described for the vacuum system and target operation conditions (current, voltage, and target distance). HRSEM imaging of biological specimens is presented to assess contrast attained from ultrathin fine grain Cr films deposited by PMSC. High magnification images were recorded to illustrate high quality contrasts attainable by HRSEM at low (1-5 kV) and high (10-30 kV) voltages. Dispersed molecules on formvar coated grids were sputter coated with a 1 nm thick Cr film before employing scanning transmission (STEM)/SEM modes of the FESEM to establish non-decorative image accuracy in the transmitted electron mode. PMID:7701300

  2. The design of the multiple resonance microcavity by reflection phase manipulation of non-QWS DBR for OLED chromaticity enhancement

    NASA Astrophysics Data System (ADS)

    Chen, Nien-Po; Chou, Meng-Hsian; Wang, Chao-Chen; Hsieh, Cheng-Jung; Chan, Yu-Cheng; Kuo, Shu-Jin

    2009-08-01

    There have been many researches regarding to the organic light-emitting diodes (OLEDs) with microcavity structures, in order to enhance its output optical properties such as chromaticity and intensity. In the applications to the white-light OLED (WOLED) and full color displays, the difficulty remains in the design of the optical length of the microcavity for proper resonance. A typical microcavity structure consists of the dielectric quarter wave stacks (QWS) as a distributed Bragg reflector (DBR) and the metal cathode to form a pair of mirrors. The organic and other material layers between the mirrors plays the role of the cavity. It can only have one major resonance peak in the perpendicular view angle and degrade the broad spectrum nature of the WOLED. Our study proposes the use of non-QWS mirror using thicker and higher-order (greater integral multiple of the quarter wavelength) of the dielectric layers. We can have the multiple resonance peak wavelengths to meet the WOLED requirement by introducing the reflection phase change of the dielectric stack mirror at certain wavelengths. The proposed microcavity structure yields a desired shift to the white point in CIE chromaticity for a typical green OLED. One of the potential applications of the microcavity with non-QWS mirror can be to make the WOLED even closer to the CIE white point without worrying the doping process variation, which is a typical problem in the WOLED. It greatly enhances the usability of the WOLED in various applications.

  3. Conditions required for high quality high magnification images in secondary electron-I scanning electron microscopy.

    PubMed

    Peters, K R

    1982-01-01

    High quality of secondary electron (SE) images, taken at useful magnifications of 100,000 to 200,000, require new signal generation and collection methods and new metal coating procedures. High quality is defined as the condition under which image contrast describes accurately the topographic features of the specimen in a size range that approximates the beam diameter. Such high resolution contrasts are produced by the SE (SE-I) generated by a small electron probe on the specimen surface. Tobacco mosiac virus and ferritin molecules deposited on bulk substrates were introduced as test specimens to check the image quality obtained. The SE-I signal contrast could be imaged when SE (SE-III), produced by backscattered electrons (BSE) at the pole piece of the final lens, were eliminated with an electron absorption device attached to the pole piece. This signal collection procedure will be referred to as "Secondary Electron-I Image" (SE-I image) mode. In addition to the SE-III, BSE generate SE-II in the specimen itself. On specimens deposited on bulk gold or platinum, and coated with the same metals SE-II produced a microroughness contrast that limited particle resolution in the SE-I image mode to approximately 10 nm. Reduction of SE-II and enrichment of the signal in SE-I was achieved by using continuous fine crystalline coatings of tantalum, niobium and chromium. By applying these metals in films of approximately 2.0 nm thickness, the SE-I contrast generation was found to be indepedent of the atomic number of the metal. Edge sharpness was improved when the specimens were coated with low atomic number metals. Under these conditions, the quality of images obtained in SE-I image mode equals that of images obtained in TEM from identically coated specimens and was limited only by the size of the topographic details, beam diameter and beam current. PMID:7184136

  4. High frequency ultrasound detection with ultra-high-Q silica microspheres

    NASA Astrophysics Data System (ADS)

    Chistiakova, Maria V.; Armani, Andrea M.

    2015-03-01

    Due to the nondestructive and noninvasive nature of ultrasound imaging, the technique has a variety of applications in many fields, most notably in healthcare and electronics. Ultrasound detection based on optical microcavities has emerged as one accurate and sensitive method. While previous research using polymer microring cavities showed detection based on device deformation, the approach presented here relied on the photoelastic effect. In this effect, the ultrasound wave induces a strain in the medium leading to a refractive index change. This effect was shown experimentally and in a COMSOL simulation with the use of ultra high quality factor silica microspheres. With an increase in quality factor and input power from previous research, the device response is increased and the noise equivalent pressure is decreased. The simulations presented use the finite element method and integrate acoustic and optics components of the system. The predictive accuracy of the simulation is also presented.

  5. Effective W-state fusion strategies for electronic and photonic qubits via the quantum-dot-microcavity coupled system.

    PubMed

    Han, Xue; Hu, Shi; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2015-01-01

    We propose effective fusion schemes for stationary electronic W state and flying photonic W state, respectively, by using the quantum-dot-microcavity coupled system. The present schemes can fuse a n-qubit W state and a m-qubit W state to a (m + n - 1)-qubit W state, that is, these schemes can be used to not only create large W state with small ones, but also to prepare 3-qubit W states with Bell states. The schemes are based on the optical selection rules and the transmission and reflection rules of the cavity and can be achieved with high probability. We evaluate the effect of experimental imperfections and the feasibility of the schemes, which shows that the present schemes can be realized with high fidelity in both the weak coupling and the strong coupling regimes. These schemes may be meaningful for the large-scale solid-state-based quantum computation and the photon-qubit-based quantum communication. PMID:26242356

  6. Low temperature plasma enhanced chemical vapor deposition of thin films combining mechanical stiffness, electrical insulation, and homogeneity in microcavities

    SciTech Connect

    Peter, S.; Guenther, M.; Hauschild, D.; Richter, F.

    2010-08-15

    The deposition of hydrogenated amorphous carbon (a-C:H) as well as hydrogenated amorphous silicon carbonitride (SiCN:H) films was investigated in view of a simultaneous realization of a minimum Young's modulus (>70 GPa), a high electrical insulation ({>=}1 MV/cm), a low permittivity and the uniform coverage of microcavities with submillimeter dimensions. For the a-C:H deposition the precursors methane (CH{sub 4}) and acetylene (C{sub 2}H{sub 2}) were used, while SiCN:H films were deposited from mixtures of trimethylsilane [SiH(CH{sub 3}){sub 3}] with nitrogen and argon. To realize the deposition of micrometer thick films with the aforementioned complex requirements at substrate temperatures {<=}200 deg. C, several plasma enhanced chemical vapor deposition methods were investigated: the capacitively coupled rf discharge and the microwave electron cyclotron resonance (ECR) plasma, combined with two types of pulsed substrate bias. SiCN:H films deposited at about 1 Pa from ECR plasmas with pulsed high-voltage bias best met the requirements. Pulsed biasing with pulse periods of about 1 {mu}s and amplitudes of about -2 kV was found to be most advantageous for the conformal low temperature coating of the microtrenches, thereby ensuring the required mechanical and insulating film properties.

  7. Quality improvement in healthcare in New Zealand. Part 1: what would a high-quality healthcare system look like?

    PubMed

    Seddon, Mary

    2006-01-01

    This Special Series attempts to define what a high-quality healthcare system would look like for New Zealand. The Series focuses on the dimensions of a quality service - safety, access, equity, effectiveness, efficiency, and patient centeredness - not only elucidating in plain language what these dimensions are, but how they might be measured and improved. The central premise is that clinicians need to become involved in measuring and improving the quality of healthcare provided. To assist clinicians, the Series will cover ways to measure the effectiveness of care they provide with articles on clinical audit and clinical indicators, and also to examine the pros and cons of the measures of efficiency used by the funders - organisational performance indicators, and benchmarking. The Series will wrap up with a vision of how we might continue to improve quality through embedding clinical governance into District Health Boards, so that their performance is measured in both quality and fiscal terms. PMID:16862202

  8. High yield seedless synthesis of high-quality gold nanocrystals with various shapes.

    PubMed

    Zhang, Jihui; Xi, Chunxiao; Feng, Cong; Xia, Haibing; Wang, Dayang; Tao, Xutang

    2014-03-11

    In this Article, high-quality gold nanocrystals (Au NCs) with various shapes including concave cubic, trisoctahedral, cubic, rod-like, and quasi-spherical have been successfully produced in high yield via adding a trace amount of NaBH4 solution into growth solutions mainly composed of HAuCl4, ascorbic acid, and surfactants. The sizes and shapes of as-prepared Au NCs can be tuned by the compositions of the growth solutions and the amount of NaBH4 added. The electrocatalytic performance of differently shaped Au NCs for methanol oxidation was studied; as-prepared trisoctahedral or concave cubic Au NCs are more highly active electrocatalysts for methanol oxidation due to the presence of high-index facets on their surface. PMID:24555832

  9. Quality assurance for clinical high intensity focused ultrasound fields.

    PubMed

    Civale, John; Rivens, Ian; ter Haar, Gail

    2015-03-01

    As the use of HIFU in the clinic becomes more widespread there is an ever increasing need to standardise quality assurance protocols, an important step in facilitating the wider acceptance of HIFU as a therapeutic modality. This article reviews pertinent aspects of HIFU treatment delivery, encompassing the closely related aspects of quality assurance and calibration. Particular attention is given to the description and characterisation of relevant acoustic field parameters and the measurement of acoustic power. Where appropriate, recommendations are made. PMID:25677839

  10. Consumers' expected quality and intention to purchase high quality pork meat.

    PubMed

    Papanagiotou, P; Tzimitra-Kalogianni, I; Melfou, K

    2013-03-01

    Expected quality is believed to be one of the most important factors that influence consumers' intention to purchase food. The present study seeks to explore the concept of pork meat expected quality and compare it with self-stated consumer intention to purchase pork meat. The aim is attempted by means of a field research conducted in Greece, following a conjoint analytic procedure. Results show that quality expectations comply with intention to buy pork, in many aspects. However, several differences have been identified. More specifically, country of origin and marbling appear to be more important for respondents' purchase decisions than they are for their quality evaluations, while the opposite appears to be true for price. Finally, socio-demographic factors such as gender, level of education, place of purchase and consumption habits seem to influence perceptions. PMID:23273449

  11. Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect.

    PubMed

    Yüce, Emre; Ctistis, Georgios; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L

    2016-01-11

    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities that operate in the "Original" (O) telecom band by exploiting the instantaneous electronic Kerr effect. We observe that the resonance frequency reversibly shifts within one picosecond when the nanostructure is pumped with low-energy photons. We investigate experimentally and theoretically the role of several parameters: the material backbone and its electronic bandgap, the quality factor, and the duration of the switch pulse. The magnitude of the frequency shift is reduced when the backbone of the central λ-layer has a greater electronic bandgap compared to the cavity resonance frequency and the frequency of the pump. This observation is caused by the fact that pumping with photon energies near the bandgap resonantly enhances the switched magnitude. We thus find that cavities operating in the telecom O-band are more amenable to ultrafast Kerr switching than those operating at lower frequencies, such as the C-band. Our results indicate that the large bandgap of AlGaAs/AlAs cavity allows to tune both the pump and the probe to the telecom range to perform Kerr switching without detrimental two-photon absorption. We observe that the magnitude of the resonance frequency shift decreases with increasing quality factor of the cavity. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the duration matches the cavity storage time to within a factor two. In our experiments, we obtain a maximum shift of the cavity resonance relative to the cavity linewidth of 20%. We project that the shift of the cavity resonance can be increased twofold with a pump pulse duration that better matches the cavity storage time. We provide the essential parameter settings for different materials so that the frequency shift of the cavity resonance can be maximized using the electronic Kerr effect. PMID:26832255

  12. 14-fs high temporal quality injector for ultra-high intensity laser

    NASA Astrophysics Data System (ADS)

    Antonucci, L.; Rousseau, J. P.; Jullien, A.; Mercier, B.; Laude, V.; Cheriaux, G.

    2009-04-01

    We present a chirped pulse amplification (CPA) Ti:Sa laser generating sub-15 fs pulses with expected high temporal quality. Gain-narrowing in the pre-amplifier is balanced by a variable spectral reflectivity mirror and by a fine adaptation of the saturation conditions. A crossed polarized wave generation (XPW) filter is introduced to enhance the contrast, reduce the pulse duration and improve the spectral quality. The pulses are generated at 10 Hz repetition rate, with pulse energy of 110 μJ and very clean Gaussian spectrum. The temporal contrast is evaluated by a measurement before the XPW filter and calculations of the enhancement by the filter. The potential temporal incoherent contrast is 10 12 and the coherent contrast 10 10. The performance of the system makes it suitable as an injector for petawatt lasers operating in the double-CPA scheme.

  13. The Physician Quality Improvement Initiative: Engaging Physicians in Quality Improvement, Patient Safety, Accountability and their Provision of High-Quality Patient Care.

    PubMed

    Wentlandt, Kirsten; Degendorfer, Niki; Clarke, Cathy; Panet, Hayley; Worthington, Jim; McLean, Richard F; Chan, Charlie K N

    2016-01-01

    University Health Network has been working to become a high-reliability organization, with a focus on safe, quality patient care. In response, the Medical Affairs Department has implemented several strategic initiatives to drive accountability, quality improvement and engagement with our physician population. One of these initiatives, the Physician Quality Improvement Initiative (PQII) is a physician-led project designed to provide active medical staff, in collaboration with their physician department chiefs, a comprehensive approach to focused and practical quality improvement in their practice. In this document, we outline the project, including its implementation strategy, logic model and outcomes, and provide discussion on how it fits into UHN's global strategy to provide safe, quality patient care. PMID:27009706

  14. Proteomic studies on soybean seed quality as affected by high temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term high temperature stresses can occur during soybean seed development through maturity and negatively impact seed quality. We investigated soybean seed quality as affected by high temperature using a proteomic approach. The effects of a prolonged high temperature treatment (37/30ºC day/nigh...

  15. Building High-Performing and Improving Education Systems: Quality Assurance and Accountability. Review

    ERIC Educational Resources Information Center

    Slater, Liz

    2013-01-01

    Monitoring, evaluation, and quality assurance in their various forms are seen as being one of the foundation stones of high-quality education systems. De Grauwe, writing about "school supervision" in four African countries in 2001, linked the decline in the quality of basic education to the cut in resources for supervision and support.…

  16. Effect of high molecular weight glutenin subunit allelic composition on wheat flour tortilla quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat cultivars possessing quality attributes needed to produce optimum quality tortillas have not been identified. This study investigated the effect of variations in high molecular weight glutenin subunits encoded at the Glu-1 loci (Glu-A1, Glu-B1, Glu-D1) on dough properties and tortilla quality....

  17. Does High School Facility Quality Affect Student Achievement? A Two-Level Hierarchical Linear Model

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Urick, Angela

    2011-01-01

    The purpose of this study is to isolate the independent effects of high school facility quality on student achievement using a large, nationally representative U.S. database of student achievement and school facility quality. Prior research on linking school facility quality to student achievement has been mixed. Studies that relate overall…

  18. Modular plant recovers high quality fuel from slurry pond

    SciTech Connect

    Batanian, D.C.; Terry, R.L.; Watters, L.A.

    1999-07-01

    fine coal recovery plant can recover an average of 100 tons per hour of high quality coal suitable for use as feedstock to the pellet plants operated at this site.

  19. Quality of health care: the responsibility of health care professionals in delivering high quality services.

    PubMed

    Giangrande, A

    1998-11-01

    According to a recent definition, quality of care consists of the degree to which health services increase the likelihood of desired health outcomes and are consistent with current professional knowledge; a definition that introduces both requirements of outcomes and the appropriateness of the process used. Clearly many different figures are interested in quality assessment initiatives in the health care field and these include patients, administrators and doctors each having different perspective. Doctors obviously pay greater attention to technical quality and results, giving greater emphasis to the health of the individual patient, tending to give priority to technical excellence and interaction between patient and doctor. Although the perspective of health care professionals is widely acknowledged to be important and useful, other perspectives on quality have been emphasised in recent years. The most important of these is the recognition that care must be responsive to the preferences and values of the consumers of health care services. In complete harmony with one's own professional commitment, the attention to the perspectives of patients must give physician the chance to identify methods of measuring and verifying quality which take account of the expectations of the many groups with an interest in improving the functioning of the health system. A global approach in the health field is needed the more specialization advances. The quality of medicine lies in its capacity to integrate what science says is appropriate and to be recommended, what can be reconciled with human rights and the self determination of the patient and what can be achieved by optimising available resources. In this complex context, the doctor could take on both the role of the person who decides on the use of resources and the one of social mediator. PMID:9894749

  20. Strong coupling of light with A and B excitons in GaN microcavities grown on silicon

    SciTech Connect

    Sellers, I. R.; Semond, F.; Leroux, M.; Massies, J.; Disseix, P.; Henneghien, A-L.; Leymarie, J.; Vasson, A.

    2006-01-15

    We present experimental results demonstrating strong-light matter coupling at low and room temperature in bulk GaN microcavities with epitaxial (Al,Ga)N Bragg mirrors grown on silicon (111). At low temperature, the strong coupling of both the A and B excitonic features of GaN with the cavity mode is clearly resolved in the microcavity. At room temperature a Rabi energy of 50 meV is observed and well reproduced using transfer-matrix reflectivity calculations describing the interaction of both the A and B excitonic states with the photonic mode.

  1. Preparation and properties of magneto-optical micro-cavities composed of Co thin film and dielectric multilayers

    NASA Astrophysics Data System (ADS)

    Inoue, M.; Matsumoto, K.; Arai, K. I.; Fujii, T.; Abe, M.

    1999-05-01

    Magneto-optical (MO) Kerr effect of micro-cavities composed of a Co thin film and SiO 2/SiN multilayer films was investigated theoretically and experimentally. The micro-cavity structure was found to be very effective for enhancing the MO Kerr effect: the MO Kerr rotation angle exceeding 10° at a designated wavelength of light was obtained, the value of which is more than 100 times larger than that of a Co single-layer film. The large MO Kerr effect is caused by the localization of light originating from the multilayer structure.

  2. Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity.

    PubMed

    Amthor, Matthias; Weißenseel, Sebastian; Fischer, Julian; Kamp, Martin; Schneider, Christian; Höfling, Sven

    2014-12-15

    We report on the condensation of microcavity exciton polaritons under optical excitation in a microcavity with four embedded InGaAs quantum wells. The polariton laser is characterized by a distinct non-linearity in the input-output-characteristics, which is accompanied by a drop of the emission linewidth indicating temporal coherence and a characteristic persisting emission blueshift with increased particle density. The temporal coherence of the device at threshold is underlined by a characteristic drop of the second order coherence function to a value close to 1. Furthermore an external electric field is used to switch between polariton regime, polariton condensate and photon lasing. PMID:25607064

  3. Innovation in Business Education: Developing a High Quality Online MBA

    ERIC Educational Resources Information Center

    Roe, C. William; Toma, Alfred G.; Yallapragada, RamMohan R.

    2015-01-01

    Online degree programs were probably pioneered by for-profit universities such as University of Phoenix. Many online degree programs were initially considered low quality academic programs compared to traditional programs. Therefore, many public and private universities were slow to adopt the online programs. However, gradually more and more…

  4. Quality Alternative Certification Programs in Special Education Ensure High Retention

    ERIC Educational Resources Information Center

    Karge, Belinda D.; McCabe, Marjorie

    2014-01-01

    Market driven alternative routes to teaching have evolved into a quality program option and not just an answer to the teacher shortage. Alternative certification is a viable means of recruiting, training, and certifying those who have a bachelor's degree and a strong desire to enter the field of teaching. California has been a leader in the…

  5. Scheme for realizing the entanglement concentration of unknown partially entangled three-photon W states assisted by a quantum dot-microcavity coupled system

    NASA Astrophysics Data System (ADS)

    Liang, Bian-Bian; Hu, Shi; Cui, Wen-Xue; An, Cheng-Shou; Xing, Yan; Hu, Jing-Si; Sun, Guo-Qing; Jiang, Xin-Xin; Wang, Hong-Fu

    2014-11-01

    Assisted by a quantum dot-microcavity coupled system, we propose an entanglement concentration scheme for concentrating two unknown partially entangled three-photon W states into a maximally entangled three-photon W state based on spin selective photon reflection from the cavity and the interference of polarized photons. In the scheme, three parties, say Alice, Bob, and Charlie in different distant locations can successfully share the maximally entangled three-photon W state with a high probability of success by local operations performed by Alice and classical communication. We calculate the probability of success of the scheme and the fidelity of the obtained three-photon W state under practical conditions, whose results show that the scheme can work in both weak coupling and strong coupling regimes.

  6. Microcavity-Free Broadband Light Outcoupling Enhancement in Flexible Organic Light-Emitting Diodes with Nanostructured Transparent Metal-Dielectric Composite Electrodes.

    PubMed

    Xu, Lu-Hai; Ou, Qing-Dong; Li, Yan-Qing; Zhang, Yi-Bo; Zhao, Xin-Dong; Xiang, Heng-Yang; Chen, Jing-De; Zhou, Lei; Lee, Shuit-Tong; Tang, Jian-Xin

    2016-01-26

    Flexible organic light-emitting diodes (OLEDs) hold great promise for future bendable display and curved lighting applications. One key challenge of high-performance flexible OLEDs is to develop new flexible transparent conductive electrodes with superior mechanical, electrical, and optical properties. Herein, an effective nanostructured metal/dielectric composite electrode on a plastic substrate is reported by combining a quasi-random outcoupling structure for broadband and angle-independent light outcoupling of white emission with an ultrathin metal alloy film for optimum optical transparency, electrical conduction, and mechanical flexibility. The microcavity effect and surface plasmonic loss can be remarkably reduced in white flexible OLEDs, resulting in a substantial increase in the external quantum efficiency and power efficiency to 47.2% and 112.4 lm W(-1). PMID:26687488

  7. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    PubMed Central

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of AB and randomly stacked structures. Herein we report a rational approach to produce large-area high quality AB stacked bilayer graphene. We show that the self-limiting effect of graphene growth on Cu foil can be broken by using a high H2/CH4 ratio in a low pressure CVD process to enable the continued growth of bilayer graphene. A high temperature and low pressure nucleation step is found to be critical for the formation of bilayer graphene nuclei with high AB stacking ratio. A rational design of a two-step CVD process is developed for the growth of bilayer graphene with high AB stacking ratio (up to 90 %) and high coverage (up to 99 %). The electrical transport studies demonstrated that devices made of the as-grown bilayer graphene exhibit typical characteristics of AB stacked bilayer graphene with the highest carrier mobility exceeding 4,000 cm2/V·s at room temperature, comparable to that of the exfoliated bilayer graphene. PMID:22906199

  8. Water Quality: A Field-Based Quality Testing Program for Middle Schools and High Schools.

    ERIC Educational Resources Information Center

    Massachusetts State Water Resources Authority, Boston.

    This manual contains background information, lesson ideas, procedures, data collection and reporting forms, suggestions for interpreting results, and extension activities to complement a water quality field testing program. Information on testing water temperature, water pH, dissolved oxygen content, biochemical oxygen demand, nitrates, total…

  9. Sn migration control at high temperature due to high deposition speed for forming high-quality GeSn layer

    NASA Astrophysics Data System (ADS)

    Taoka, Noriyuki; Capellini, Giovanni; von den Driesch, Nils; Buca, Dan; Zaumseil, Peter; Schubert, Markus Andreas; Klesse, Wolfgang Matthias; Montanari, Michele; Schroeder, Thomas

    2016-03-01

    A key factor for controlling Sn migration during GeSn deposition at a high temperature of 400 °C was investigated. Calculated results with a simple model for the Sn migration and experimental results clarified that low-deposition-speed (vd) deposition with vd’s of 0.68 and 2.8 nm/min induces significant Sn precipitation, whereas high-deposition-speed (vd = 13 nm/min) deposition leads to high crystallinity and good photoluminescence spectrum of the GeSn layer. These results indicate that vd is a key parameter, and that control of Sn migration at a high temperature is possible. These results are of great relevance for the application of high-quality Sn-based alloys in future optoelectronics devices.

  10. Analogies between optical propagation and heat diffusion: applications to microcavities, gratings and cloaks

    PubMed Central

    Amra, C.; Petiteau, D.; Zerrad, M.; Guenneau, S.; Soriano, G.; Gralak, B.; Bellieud, M.; Veynante, D.; Rolland, N.

    2015-01-01

    A new analogy between optical propagation and heat diffusion in heterogeneous anisotropic media has been proposed recently by three of the present authors. A detailed derivation of this unconventional correspondence is presented and developed. In time harmonic regime, all thermal parameters are related to optical ones in artificial metallic media, thus making possible to use numerical codes developed for optics. Then, the optical admittance formalism is extended to heat conduction in multilayered structures. The concepts of planar microcavities, diffraction gratings and planar transformation optics for heat conduction are addressed. Results and limitations of the analogy are emphasized. PMID:26730214

  11. Microcavity with saturable nonlinearity under simultaneous resonant and nonresonant pumping: multistability, Hopf bifurcations and chaotic behaviour.

    PubMed

    Iorsh, Ivan; Alodjants, Alexander; Shelykh, Ivan A

    2016-05-30

    We studied optical response of microcavity non-equilibrium exciton-polariton Bose-Einstein condensate with saturable nonlinearity under simultaneous resonant and non-resonant pumping. We demonstrated the emergence of multistabile behavior due to the saturation of the excitonic absorption. Stable periodic Rabi-type oscillations of the excitonic and photonic condensate components in the regime of the stationary pump and their transition to the chaotic dynamics through the cascade of Hopf bifurcations by tuning of the electrical pump are revealed. PMID:27410078

  12. Inducing Photonic Transitions between Discrete Modes in a Silicon Optical Microcavity

    NASA Astrophysics Data System (ADS)

    Dong, Po; Preble, Stefan F.; Robinson, Jacob T.; Manipatruni, Sasikanth; Lipson, Michal

    2008-01-01

    We show the existence of direct photonic transitions between modes of a silicon optical microcavity spaced apart in wavelength by over 8 nm. This is achieved by using ultrafast tuning of the refractive index of the cavity over a time interval that is comparable to the inverse of the frequency separation of modes. The demonstrated frequency mixing effect, i.e., the transitions between the modes, would enable on-chip silicon comb sources which can find wide applications in optical sensing, precise spectroscopy, and wavelength-division multiplexing for optical communications and interconnects.

  13. Strongly enhanced mode selection in a thin dielectric-coated layered microcavity laser

    NASA Astrophysics Data System (ADS)

    Moon, Hee-Jong; Kang, Dong-Yun

    2007-06-01

    Strong mode selection through an enhanced interferential coupling effect was observed in a thin dielectric-coated layered cylindrical microcavity laser. The strong coupling effect was induced owing to an enhanced reflectivity of around 50% at the dielectric-coated inner boundary of a fused silica capillary filled with a dye-doped liquid. At an optimized coating thickness of about 0.4 μm, the lasing peaks appeared only at the wavelengths corresponding to the constructive interference condition, whereas those from a bare capillary were weakly modulated.

  14. Manufacturing High-Quality Carbon Nanotubes at Lower Cost

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M.; Lidecker, Henning

    2004-01-01

    A modified electric-arc welding process has been developed for manufacturing high-quality batches of carbon nanotubes at relatively low cost. Unlike in some other processes for making carbon nanotubes, metal catalysts are not used and, consequently, it is not necessary to perform extensive cleaning and purification. Also, unlike some other processes, this process is carried out at atmospheric pressure under a hood instead of in a closed, pressurized chamber; as a result, the present process can be implemented more easily. Although the present welding-based process includes an electric arc, it differs from a prior electric-arc nanotube-production process. The welding equipment used in this process includes an AC/DC welding power source with an integral helium-gas delivery system and circulating water for cooling an assembly that holds one of the welding electrodes (in this case, the anode). The cathode is a hollow carbon (optionally, graphite) rod having an outside diameter of 2 in. (approximately equal to 5.1 cm) and an inside diameter of 5/8 in. (approximately equal to 1.6 cm). The cathode is partly immersed in a water bath, such that it protrudes about 2 in. (about 5.1 cm) above the surface of the water. The bottom end of the cathode is held underwater by a clamp, to which is connected the grounding cable of the welding power source. The anode is a carbon rod 1/8 in. (approximately equal to 0.3 cm) in diameter. The assembly that holds the anode includes a thumbknob- driven mechanism for controlling the height of the anode. A small hood is placed over the anode to direct a flow of helium downward from the anode to the cathode during the welding process. A bell-shaped exhaust hood collects the helium and other gases from the process. During the process, as the anode is consumed, the height of the anode is adjusted to maintain an anode-to-cathode gap of 1 mm. The arc-welding process is continued until the upper end of the anode has been lowered to a specified height

  15. Swelling of nuclear graphite and high quality carbon fiber composite under very high irradiation temperature

    NASA Astrophysics Data System (ADS)

    Snead, L. L.; Burchell, T. D.; Katoh, Y.

    2008-10-01

    The purpose of this experiment was to evaluate the dimensional change of newly proposed nuclear graphite material following high-temperature irradiation, and to compare the measured swelling with the historic nuclear graphite, H-451. Over the irradiation temperature range studied (˜850-1475 °C) and neutron dose range (2-10 × 10 25 n/m 2 ( E > 0.1 MeV)) the Graftech PCEA and SGL NBG-10 candidate nuclear graphite had similar densification to that of Great Lakes Carbon nuclear graphite H-451. In this temperature and dose range all materials remained in the densification stage. Additionally, the effect of high-temperature irradiation on the dimensional stability of high-quality carbon fiber composites was investigated. A high thermal conductivity three-dimensional carbon fiber composite, FMI-222, and a very high thermal conductivity one-dimensional carbon fiber composite MKC-1PH, were studied. Results indicate that a greater than anticipated dimensional change occurred for these composites. Moreover, the dimensional stability of the 3D composite appears to be a strong function of the sample size chosen, thus raising the question of the appropriate size sample to use to determine irradiation-induced dimensional change for these materials.

  16. Numerical determination of injector design for high beam quality

    SciTech Connect

    Boyd, J.K.

    1985-10-15

    The performance of a free electron laser strongly depends on the electron beam quality or brightness. The electron beam is transported into the free electron laser after it has been accelerated to the desired energy. Typically the maximum beam brightness produced by an accelerator is constrained by the beam brightness deliverd by the accelerator injector. Thus it is important to design the accelerator injector to yield the required electron beam brightness. The DPC (Darwin Particle Code) computer code has been written to numerically model accelerator injectors. DPC solves for the transport of a beam from emission through acceleration up to the full energy of the injector. The relativistic force equation is solved to determine particle orbits. Field equations are solved for self consistent electric and magnetic fields in the Darwin approximation. DPC has been used to investigate the beam quality consequences of A-K gap, accelerating stress, electrode configuration and axial magnetic field profile.

  17. High image quality sub 100 picosecond gated framing camera development

    SciTech Connect

    Price, R.H.; Wiedwald, J.D.

    1983-11-17

    A major challenge for laser fusion is the study of the symmetry and hydrodynamic stability of imploding fuel capsules. Framed x-radiographs of 10-100 ps duration, excellent image quality, minimum geometrical distortion (< 1%), dynamic range greater than 1000, and more than 200 x 200 pixels are required for this application. Recent progress on a gated proximity focused intensifier which meets these requirements is presented.

  18. Health-Related Quality of Life in Children with High-Functioning Autism

    ERIC Educational Resources Information Center

    Potvin, Marie-Christine; Snider, Laurie; Prelock, Patricia A.; Wood-Dauphinee, Sharon; Kehayia, Eva

    2015-01-01

    The health-related quality of life of school-aged children with high-functioning autism is poorly understood. The objectives of this study were to compare the health-related quality of life of children with high-functioning autism to that of typically developing peers and to compare child-self and parent-proxy reports of health-related quality of…

  19. Select Novice Elementary Teachers' Perceived Knowledge and Implementation of High-Quality Reading Instruction

    ERIC Educational Resources Information Center

    Bumstead, Stacey

    2012-01-01

    The purpose of this mixed methods study was to examine select novice teachers' perceived knowledge of high-quality reading instruction, explore the extent that select novice teachers implemented high-quality reading instruction into their own classrooms, and to investigate any factors that explain the similarities and differences between…

  20. Child Care and Mothers' Mental Health: Is High-Quality Care Associated with Fewer Depressive Symptoms?

    ERIC Educational Resources Information Center

    Gordon, Rachel A.; Usdansky, Margaret L.; Wang, Xue; Gluzman, Anna

    2011-01-01

    Finding high-quality child care may pose financial and logistical challenges and create ongoing emotional strains for some mothers. We use the Study of Early Child Care and Youth Development to ask (a) are child-care settings that mothers select on the basis of their own perceptions of quality rated more highly by independent observers (and more…

  1. Creating High-Quality Preschool: Ideas for Supporting Early Learning Programs. [Videotape].

    ERIC Educational Resources Information Center

    Department of Education, Washington, DC.

    Recognizing that a quality preschool program is key to children's high achievement, this videotape presents a U.S. Department of Education teleconference on creating high quality preschool programs and federal funding available for such programs. Panelists from the Department include the director of the Early Childhood Institute in the Office of…

  2. Ready to Start: Ensuring High-Quality Prekindergarten in SREB States. Challenge to Lead Series

    ERIC Educational Resources Information Center

    Thomas, Marilyn G.; Lord, Joan M.

    2007-01-01

    Southern Regional Education Board (SREB) states are trailblazers in providing access to high-quality, state-funded pre-kindergarten for 4-year-olds: last year, the majority of all 4-year-olds attending pre-kindergarten in the nation were enrolled in SREB states. The SREB region also leads the nation in setting high standards of quality for…

  3. A Survey on the Democratic Qualities of High School Students and the Schooling for Democracy

    ERIC Educational Resources Information Center

    Xu, Rui

    2009-01-01

    Using the method of purpositive sampling, this research makes an empirical study on the relationship between the schooling for education and democratic qualities of public high school students in Beijing. The results show that the democratic qualities of the students in public high school of Beijing are better as a whole, but they are still lack…

  4. Roadmap for High School Feedback Reports: Key Focus Areas to Ensure Quality Implementation. Data for Action

    ERIC Educational Resources Information Center

    Data Quality Campaign, 2014

    2014-01-01

    High school feedback reports let school and district leaders know where their students go after graduation and how well they are prepared for college and beyond. This roadmap discusses the seven key focus areas the Data Quality Campaign (DQC) recommends states work on to ensure quality implementation of high school feedback reports.

  5. The Cost of High-Quality Pre-School Education in New Jersey

    ERIC Educational Resources Information Center

    Belfield, Clive; Schwartz, Heather

    2007-01-01

    This report calculates the full cost of providing well-planned, high quality pre-school for children in New Jersey, as required under "Abbott vs. Burke" (153 NJ 480 1998). The evidence on how high-quality pre-school improves the academic performance of children is compelling. After a rapid expansion over the last decade, many children in the…

  6. High Fidelity System Modeling for High Quality Image Reconstruction in Clinical CT

    PubMed Central

    Do, Synho; Karl, William Clem; Singh, Sarabjeet; Kalra, Mannudeep; Brady, Tom; Shin, Ellie; Pien, Homer

    2014-01-01

    Today, while many researchers focus on the improvement of the regularization term in IR algorithms, they pay less concern to the improvement of the fidelity term. In this paper, we hypothesize that improving the fidelity term will further improve IR image quality in low-dose scanning, which typically causes more noise. The purpose of this paper is to systematically test and examine the role of high-fidelity system models using raw data in the performance of iterative image reconstruction approach minimizing energy functional. We first isolated the fidelity term and analyzed the importance of using focal spot area modeling, flying focal spot location modeling, and active detector area modeling as opposed to just flying focal spot motion. We then compared images using different permutations of all three factors. Next, we tested the ability of the fidelity terms to retain signals upon application of the regularization term with all three factors. We then compared the differences between images generated by the proposed method and Filtered-Back-Projection. Lastly, we compared images of low-dose in vivo data using Filtered-Back-Projection, Iterative Reconstruction in Image Space, and the proposed method using raw data. The initial comparison of difference maps of images constructed showed that the focal spot area model and the active detector area model also have significant impacts on the quality of images produced. Upon application of the regularization term, images generated using all three factors were able to substantially decrease model mismatch error, artifacts, and noise. When the images generated by the proposed method were tested, conspicuity greatly increased, noise standard deviation decreased by 90% in homogeneous regions, and resolution also greatly improved. In conclusion, the improvement of the fidelity term to model clinical scanners is essential to generating higher quality images in low-dose imaging. PMID:25390888

  7. Measurement system with high accuracy for laser beam quality.

    PubMed

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%. PMID:26192526

  8. High-quality healthcare workplaces: a vision and action plan.

    PubMed

    Lowe, Graham S

    2002-01-01

    Looking into a future marked by intense competition for talent, growing numbers of employers are striving to create "workplaces of choice." Yet, despite the consensus that health human resources are a vital piece of the healthcare reform puzzle, few health service organizations have developed comprehensive strategies to address work environment issues. The cumulative impact of years of cost-cutting, downsizing and restructuring have left Canada's healthcare workforce demoralized, overworked and coping with working conditions that diminish both the quality of working life and organizational performance. PMID:12357573

  9. High-Quality LB Films of Artificial Dialkyl Lipid

    NASA Astrophysics Data System (ADS)

    Onoue, Yoichi; Moriizumi, Toyosaka; Okahata, Yoshio; Ariga, Katsuhiko

    1987-11-01

    LB films (4 monolayers) of artificial dialkyl lipid were deposited over Au evaporated films on glass substrates. The film quality was examined using the Cu decoration method and optical polarization microscopy. The defect density of the lipid film was much less than that of a monoalkyl film. Moreover, the defect density was so decreased after thermal annealing and rinsing in an alcohol solution that LB films which were almost defect-free were obtained. Microscopic observation revealed a snowflake crystalline pattern after the annealing and rinsing treatments.

  10. Publishing high-quality climate data on the semantic web

    NASA Astrophysics Data System (ADS)

    Woolf, Andrew; Haller, Armin; Lefort, Laurent; Taylor, Kerry

    2013-04-01

    The effort over more than a decade to establish the semantic web [Berners-Lee et. al., 2001] has received a major boost in recent years through the Open Government movement. Governments around the world are seeking technical solutions to enable more open and transparent access to Public Sector Information (PSI) they hold. Existing technical protocols and data standards tend to be domain specific, and so limit the ability to publish and integrate data across domains (health, environment, statistics, education, etc.). The web provides a domain-neutral platform for information publishing, and has proven itself beyond expectations for publishing and linking human-readable electronic documents. Extending the web pattern to data (often called Web 3.0) offers enormous potential. The semantic web applies the basic web principles to data [Berners-Lee, 2006]: using URIs as identifiers (for data objects and real-world 'things', instead of documents) making the URIs actionable by providing useful information via HTTP using a common exchange standard (serialised RDF for data instead of HTML for documents) establishing typed links between information objects to enable linking and integration Leading examples of 'linked data' for publishing PSI may be found in both the UK (http://data.gov.uk/linked-data) and US (http://www.data.gov/page/semantic-web). The Bureau of Meteorology (BoM) is Australia's national meteorological agency, and has a new mandate to establish a national environmental information infrastructure (under the National Plan for Environmental Information, NPEI [BoM, 2012a]). While the initial approach is based on the existing best practice Spatial Data Infrastructure (SDI) architecture, linked-data is being explored as a technological alternative that shows great promise for the future. We report here the first trial of government linked-data in Australia under data.gov.au. In this initial pilot study, we have taken BoM's new high-quality reference surface

  11. Ultra-compact and wide-spectrum-range thermo-optic switch based on silicon coupled photonic crystal microcavities

    SciTech Connect

    Zhang, Xingyu E-mail: swapnajit.chakravarty@omegaoptics.com Chung, Chi-Jui; Pan, Zeyu; Yan, Hai; Chakravarty, Swapnajit E-mail: swapnajit.chakravarty@omegaoptics.com; Chen, Ray T. E-mail: swapnajit.chakravarty@omegaoptics.com

    2015-11-30

    We design, fabricate, and experimentally demonstrate a compact thermo-optic gate switch comprising a 3.78 μm-long coupled L0-type photonic crystal microcavities on a silicon-on-insulator substrate. A nanohole is inserted in the center of each individual L0 photonic crystal microcavity. Coupling between identical microcavities gives rise to bonding and anti-bonding states of the coupled photonic molecules. The coupled photonic crystal microcavities are numerically simulated and experimentally verified with a 6 nm-wide flat-bottom resonance in its transmission spectrum, which enables wider operational spectrum range than microring resonators. An integrated micro-heater is in direct contact with the silicon core to efficiently drive the device. The thermo-optic switch is measured with an optical extinction ratio of 20 dB, an on-off switching power of 18.2 mW, a thermo-optic tuning efficiency of 0.63 nm/mW, a rise time of 14.8 μs, and a fall time of 18.5 μs. The measured on-chip loss on the transmission band is as low as 1 dB.

  12. Microcavity arrays as an in vitro model system of the bone marrow niche for hematopoietic stem cells.

    PubMed

    Wuchter, Patrick; Saffrich, Rainer; Giselbrecht, Stefan; Nies, Cordula; Lorig, Hanna; Kolb, Stephanie; Ho, Anthony D; Gottwald, Eric

    2016-06-01

    In previous studies human mesenchymal stromal cells (MSCs) maintained the "stemness" of human hematopoietic progenitor cells (HPCs) through direct cell-cell contact in two-dimensional co-culture systems. We establish a three-dimensional (3D) co-culture system based on a custom-made chip, the 3(D)-KITChip, as an in vitro model system of the human hematopoietic stem cell niche. This array of up to 625 microcavities, with 300 μm size in each orientation, was inserted into a microfluidic bioreactor. The microcavities of the 3(D)-KITChip were inoculated with human bone marrow MSCs together with umbilical cord blood HPCs. MSCs used the microcavities as a scaffold to build a complex 3D mesh. HPCs were distributed three-dimensionally inside this MSC network and formed ß-catenin- and N-cadherin-based intercellular junctions to the surrounding MSCs. Using RT(2)-PCR and western blots, we demonstrate that a proportion of HPCs maintained the expression of CD34 throughout a culture period of 14 days. In colony-forming unit assays, the hematopoietic stem cell plasticity remained similar after 14 days of bioreactor co-culture, whereas monolayer co-cultures showed increasing signs of HPC differentiation and loss of stemness. These data support the notion that the 3D microenvironment created within the microcavity array preserves vital stem cell functions of HPCs more efficiently than conventional co-culture systems. PMID:26829941

  13. Optofluidic Modulation of Self-Associated Nanostructural Units Forming Planar Bragg Microcavities.

    PubMed

    Oliva-Ramirez, Manuel; Barranco, Angel; Löffler, Markus; Yubero, Francisco; González-Elipe, Agustin R

    2016-01-26

    Bragg microcavities (BMs) formed by the successive stacking of nanocolumnar porous SiO2 and TiO2 layers with slanted, zigzag, chiral, and vertical configurations are prepared by physical vapor deposition at oblique angles while azimuthally varying the substrate orientation during the multilayer growth. The slanted and zigzag BMs act as wavelength-selective optical retarders when they are illuminated with linearly polarized light, while no polarization dependence is observed for the chiral and vertical cavities. This distinct optical behavior is attributed to a self-nanostructuration mechanism involving a fence-bundling association of nanocolumns as observed by focused ion beam scanning electron microscopy in the slanted and zigzag microcavities. The outstanding retarder response of the optically active BMs can be effectively modulated by dynamic infiltration of nano- and mesopores with liquids of different refraction indices acting as a switch of the polarization behavior. The unprecedented polarization and tunable optofluidic properties of these nanostructured photonic systems have been successfully simulated with a simple model that assumes a certain birefringence for the individual stacked layers and accounts for the light interference phenomena developed in the BMs. The possibilities of this type of self-arranged nanostructured and optically active BMs for liquid sensing and monitoring applications are discussed. PMID:26653767

  14. Photonic lattices in organic microcavities: Bloch states and control of lasing

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Fröb, Hartmut; Lyssenko, Vadim G.; Leo, Karl

    2015-09-01

    Organic microcavities comprising the host:guest emitter system Alq3:DCM offer an interesting playground to experimentally study the dispersion characteristics of laterally patterned microlasers due to the broad emission spectrum and large oscillator strength of the organic dye. By structuring of metallic or dielectric sublayers directly on top of the bottom mirror, we precisely manipulate the mode structure and influence the coherent emission properties of the device. Embedding silver layers into a microcavity leads to an interaction of the optical cavity-state in the organic layer and the neighboring metal which red-shifts the cavity resonance, creating a Tamm-plasmon-polariton state. A patterning of the metal can in turn be exploited to fabricate deep photonic wells of micron-size, efficiently confining light in lateral direction. In periodic arrays of silver wires, we create a Kronig-Penney-like optical potential in the cavity and in turn observe optical Bloch states spanning over several photonic wires. We modify the Kronig-Penney theory to analytically describe the full far-field emission dispersion of our cavities and show the emergence of either zero- , π-, or 2π- phase-locking in the system. By investigating periodic SiO2 patterns, we experimentally observe stimulated emission from the ground and different excited discrete states at room temperature and are able to directly control the laser emission from both extended and confined modes of the photonic wires at room-temperature.

  15. Optical properties of single infrared resonant circular microcavities for surface phonon polaritons.

    PubMed

    Wang, Tao; Li, Peining; Hauer, Benedikt; Chigrin, Dmitry N; Taubner, Thomas

    2013-11-13

    Plasmonic antennas are crucial components for nano-optics and have been extensively used to enhance sensing, spectroscopy, light emission, photodetection, and others. Recently, there is a trend to search for new plasmonic materials with low intrinsic loss at new plasmon frequencies. As an alternative to metals, polar crystals have a negative real part of permittivity in the Reststrahlen band and support surface phonon polaritons (SPhPs) with weak damping. Here, we experimentally demonstrate the resonance of single circular microcavities in a thin gold film deposited on a silicon carbide (SiC) substrate in the mid-infrared range. Specifically, the negative permittivity of SiC leads to a well-defined, size-tunable SPhP resonance with a Q factor of around 60 which is much higher than those in surface plasmon polariton (SPP) resonators with similar structures. These infrared resonant microcavities provide new possibilities for widespread applications such as enhanced spectroscopy, sensing, coherent thermal emission, and infrared photodetectors among others throughout the infrared frequency range. PMID:24117024

  16. Dynamical Fano-Like Interference between Rabi Oscillations and Coherent Phonons in a Semiconductor Microcavity System

    NASA Astrophysics Data System (ADS)

    Yoshino, S.; Oohata, G.; Mizoguchi, K.

    2015-10-01

    We report on dynamical interference between short-lived Rabi oscillations and long-lived coherent phonons in CuCl semiconductor microcavities resulting from the coupling between the two oscillations. The Fourier-transformed spectra of the time-domain signals obtained from semiconductor microcavities by using a pump-probe technique show that the intensity of the coherent longitudinal optical phonon of CuCl is enhanced by increasing that of the Rabi oscillation, which indicates that the coherent phonon is driven by the Rabi oscillation through the Fröhlich interaction. Moreover, as the Rabi oscillation frequency decreases upon crossing the phonon frequency, the spectral profile of the coherent phonon changes from a peak to a dip with an asymmetric structure. The continuous wavelet transformation reveals that these peak and dip structures originate from constructive and destructive interference between Rabi oscillations and coherent phonons, respectively. We demonstrate that the asymmetric spectral structures in relation to the frequency detuning are well reproduced by using a classical coupled oscillator model on the basis of dynamical Fano-like interference.

  17. Pulsed microplasmas generated in truncated paraboloidal microcavities: simulations of particle densities and energy flow

    NASA Astrophysics Data System (ADS)

    Lee, H.-J.; Park, S.-J.; Eden, J. G.

    2012-10-01

    Microplasmas generated within cavities having the form of a truncated paraboloid, introduced by Kim et al (2009 Appl. Phys. Lett. 94 011503), have been simulated numerically with a two-dimensional, fluid computational model. Microcavities with parabolic sidewalls, fabricated in nanoporous alumina (Al2O3) and having upper (primary emitter) and lower apertures of 150 µm and 75 µm in diameter, respectively, are driven by a bipolar voltage waveform at a frequency of 200 kHz. For a Ne pressure of 500 Torr and 2 µs, 290 V pulses constituting each half-cycle of the driving voltage waveform, calculations predict that ˜10 nJ of energy is delivered to each parabolic cavity, of which 26-30% is consumed by the electrons. Once the cathode fall is formed, approximately 65% and 8% of the input energy is devoted to driving the atomic ion and dimer ion (Ne_2^+ ) currents, respectively, and the peak electron density of ˜6 × 1012 cm-3 is attained ˜90 ns following the onset of the first half-cycle (positive) voltage pulse. Specific power loading of the microplasma reaches 150 kW cm-3 and the loss of power to the wall of the microcavity drops by as much as 24% when the excitation voltage is increased from 280 to 310 V. The diminished influence of diffusion with increasing pressure is responsible for wall losses at 600 Torr accounting for <20% of the total electron energy.

  18. Organic white-light-emitting devices based on a multimode resonant microcavity

    NASA Astrophysics Data System (ADS)

    Zhang, Hongmei; You, Han; Wang, Wei; Shi, Jiawei; Guo, Shuxu; Liu, Mingda; Ma, Dongge

    2006-08-01

    Organic white-light-emitting devices (OLEDs) based on a multimode resonant microcavity defined by a pair of dielectric mirrors and metal mirrors were presented. By selective effects of the quarter-wave dielectric stack mirror on mode, white light emission containing three individual narrow peaks of red, green and blue was achieved, and showed weak dependence on the viewing angle. The Commission Internationale De L'Eclairage (CIE) chromaticity coordinates changed from (0.29, 0.37) at 0° to (0.31, 0.33) at 40°. Furthermore, the brightness and electroluminescence efficiency of the microcavity OLEDs were enhanced compared with noncavity OLEDs. The maximum brightness reached 1940 cd m-2 at a current density of 200 mA cm-2, and the maximum current efficiency and power efficiency are 1.6 cd A-1 at a current density of 12 mA cm-2 and 0.41 lm W-1 at a current density of 1.6 mA cm-2, which are over 1.6 times higher than that of a noncavity OLED.

  19. Dynamical Fano-Like Interference between Rabi Oscillations and Coherent Phonons in a Semiconductor Microcavity System.

    PubMed

    Yoshino, S; Oohata, G; Mizoguchi, K

    2015-10-01

    We report on dynamical interference between short-lived Rabi oscillations and long-lived coherent phonons in CuCl semiconductor microcavities resulting from the coupling between the two oscillations. The Fourier-transformed spectra of the time-domain signals obtained from semiconductor microcavities by using a pump-probe technique show that the intensity of the coherent longitudinal optical phonon of CuCl is enhanced by increasing that of the Rabi oscillation, which indicates that the coherent phonon is driven by the Rabi oscillation through the Fröhlich interaction. Moreover, as the Rabi oscillation frequency decreases upon crossing the phonon frequency, the spectral profile of the coherent phonon changes from a peak to a dip with an asymmetric structure. The continuous wavelet transformation reveals that these peak and dip structures originate from constructive and destructive interference between Rabi oscillations and coherent phonons, respectively. We demonstrate that the asymmetric spectral structures in relation to the frequency detuning are well reproduced by using a classical coupled oscillator model on the basis of dynamical Fano-like interference. PMID:26550752

  20. Multifrequency filtering characters of two-dimensional photonic crystals with rectangular microcavities

    NASA Astrophysics Data System (ADS)

    Feng, Shuai; Li, Jiewen; Guo, Yuan; Wang, Yiquan

    2014-01-01

    Multifrequency filtering characteristics of the two-dimensional square-lattice photonic crystal structures with rectangular microcavities are studied. Owing to the different sensitivities of the resonant frequencies to the variation of the rectangle's side length, one resonant frequency can be flexibly adjusted only by changing one of the rectangle's side lengths, while another frequency is immunizing to the variation. So, a two-output-channel frequency filter is designed to allow two frequencies to travel along different channels, and allow the third frequency to travel along both the channels. Based on the low spatial symmetry of rectangular defect, which supports localized modes with different symmetries, together with optimizing the coupling regions between the input waveguide and the rectangular microcavities, the two-output-channel and four-output-channel filters are both achieved, which can select different frequencies to travel along various channels, and share another frequency to travel along every output channel. These kinds of devices have both the abilities of information selecting and sharing carried out by different frequencies, and may have potential applications in the future complex all-optical integrated circuits.

  1. Theoretical and experimental study of nanoporous silicon photonic microcavity optical sensor devices

    NASA Astrophysics Data System (ADS)

    Patel, P. N.; Mishra, Vivekanand; Panchal, A. K.

    2012-09-01

    This paper reports the theoretical and experimental study of one-dimensional (1D) multilayer nanoporous silicon (NPS) photonic band gap (PBG) microcavity (MC) structures for optical sensor device applications. A theoretical framework to model the reflectance spectra relying on the Bruggeman's effective medium approximation (BEMA) and the transfer matrix method (TMM) was established for the 1D nanoporous silicon microcavity (1D-NPSMC) optical sensor device structures. Based on the theoretical background, 1D-NPSMC sensor device structures were fabricated using electrochemical dissolution of silicon wafer in hydrofluoric (HF) acid. The refractive index of the 1D-NPSMC structures was tuned by changing current density and the thickness was tuned by changing the etching time. Wavelength shifts (Δλ) in the measured reflectance spectra were analyzed for the detection of the analyte in the porous structure. The sensing device performance was tested by different organic solvents, which showed good linear relation between the refractive index of analyte inside the pores and the wavelength shift. The application of proposed structures can be extended for the optical sensing of chemicals, gas, environmental pollutants, pathogens etc.

  2. Exciton-polariton in graphene nano-ribbon embedded In semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Shojaei, S.; Imannezhad, S.

    2016-03-01

    In this paper, we investigated coupling of confined photons in the semiconductor microcavity consists of Distributed Bragg Reflectors (DBR) (Si3N4/SiO2 and AlAs/Al0.1Ga0.9As) with excitons of gapped Armchair Graphene NanoRibbon (A-GNR) that placed at the maximum of electric field amplitude inside the semiconductor microcavity. Our calculations show that the coupling between GNR's exciton and confined photon modes and appearance of vacuum Rabi splitting (VRS), is possible. By the means of Transfer Matrix Method (TMM) we obtain angle dependent reflectance spectrum and Upper, Lower Polariton Branches (UPB&LPB) for the structure. Clear anticrossing between the neutral exciton and the cavity modes with a splitting of about 3 meV obtained that can be enhanced in double-GNR. While, our calculations certify the formation of graphene based exciton-polariton, propose the enhancement of VRS by optimization of relevant parameters to implement the graphene based cavity polaritons in optoelectronic devices.

  3. The high cost of low quality in R D (research and development)

    SciTech Connect

    Wells, C.V.

    1990-10-01

    The principles of quality assurance and quality control yield high payoffs when applied to research activities. Researchers are usually highly motivated individuals who earnestly desire to produce excellent results. The nature of research and the temperament of researchers are such that considerable freedom and latitude are usually required so that the creative processes are not impeded. These are approaches that can be used in applying quality assurance and control that researchers will accept and use when they see the payoff. Some examples are given, with particular emphasis on quality cost systems applied to measurement processes in R D. 14 refs.

  4. High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc

    SciTech Connect

    Mendelsberg, Rueben J.; Lim, S.H.N.; Milliron, D.J.; Anders, Andre

    2010-11-18

    High quality ZnO:Al (AZO) thin films were prepared on glass substrates by direct current filtered cathodic arc deposition. Substrate temperature was varied from room temperature to 425oC, and samples were grown with and without the assistance of low power oxygen plasma (75W). For each growth condition, at least 3 samples were grown to give a statistical look at the effect of the growth environment on the film properties and to explore the reproducibility of the technique. Growth rate was in the 100-400 nm/min range but was apparently random and could not be easily traced to the growth conditions explored. For optimized growth conditions, 300-600 nm AZO films had resistivities of 3-6 x 10-4 ?Omega cm, carrier concentrations in the range of 2-4 x 1020 cm3, Hall mobility as high as 55 cm2/Vs, and optical transmittance greater than 90percent. These films are also highly oriented with the c-axis perpendicular to the substrate and a surface roughness of 2-4 nm.

  5. Direct preparation of high quality graphene on dielectric substrates.

    PubMed

    Chen, Xin; Wu, Bin; Liu, Yunqi

    2016-04-21

    Graphene, an amazing two-dimensional material with excellent physical properties, has attracted great attention in various disciplines. Both fundamental studies and applications require graphene samples with controlled parameters including their quality, size, crystallinity, layer number and so on. While graphene can be prepared by direct exfoliation from mother materials or growth on transition metals, the uncontrolled production or the additional complex transfer process has been challenging for graphene applications. Direct preparation on a desired dielectric substrate is an important research direction that potentially addresses these problems. Many advances have been made in the past few years, and this tutorial review provides a brief summary of ways of preparing graphene on dielectric substrates. Various methods including the annealing method, direct chemical vapor deposition graphene synthesis on conventional dielectric substrates and hexagonal boron nitride layers are systematically reviewed and discussed. The main problems and further directions in this field are also presented. PMID:26847929

  6. Obtaining High Quality DNA from Diverse Clinical Samples.

    PubMed

    Melton-Kreft, Rachael; Spirk, Tracy

    2016-01-01

    Nucleic acids can be obtained in numerous ways from clinical specimens; however, the quality of the nucleic acid is only as good as the sampling and isolation protocol. While nucleic acids may be extracted they may not be representative of the original source. Large areas of tissue and explanted hardware must be successfully surveyed to reflect the overall clinical picture. Once good sampling technique has been established, successful bacterial nucleic acid isolation is essential. Clinical samples may be difficult to process because of the presence of scar tissue, bone, implants, and bacterial biofilms. The following protocols provide details on sampling techniques and DNA isolation from a variety of clinical samples which can then be used in downstream molecular applications including PCR-MS-ESI-TOF technology. © 2016 by John Wiley & Sons, Inc. PMID:26855284

  7. High quality Gaussian basis sets for fourth-row atoms

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Faegri, Knut, Jr.

    1992-01-01

    Energy optimized Gaussian basis sets of triple-zeta quality for the atoms Rb-Xe have been derived. Two series of basis sets are developed: (24s 16p 10d) and (26s 16p 10d) sets which were expanded to 13d and 19p functions as the 4d and 5p shells become occupied. For the atoms lighter than Cd, the (24s 16p 10d) sets with triple-zeta valence distributions are higher in energy than the corresponding double-zeta distribution. To ensure a triple-zeta distribution and a global energy minimum, the (26s 16p 10d) sets were derived. Total atomic energies from the largest basis sets are between 198 and 284 (mu)E(sub H) above the numerical Hartree-Fock energies.

  8. High quality exchange rotations in spin qubits using symmetric gating

    NASA Astrophysics Data System (ADS)

    Martins, F.; Malinowski, F. K.; Nissen, P. D.; Marcus, C. M.; Kuemmeth, F.; Barnes, E.; Gardner, G. C.; Fallahi, S.; Manfra, M. J.

    We present results on a singlet-triplet qubit implemented in a GaAs/AlGaAs heterostructure and we show that exchange oscillations can be realized either by tilting the double well potential, the conventional method, or by symmetrically lowering the barrier, as originally suggested by Loss and DiVincenzo. The two methods are compared here. We find that lowering the barrier between dots has much less relative exchange noise compared to tilting the potential. Since exchange rotations are sensitive to electrical noise and relatively insensitive to nuclear noise, this yields significantly enhanced free induction decay times and quality factors. Our results are comparable to those reported recently in silicon quantum dot devices, obtained using similar techniques. Support through IARPA-MQCO, LPS-MPO-CMTC, Army Research Office, and the Danish National Research Foundation is acknowledged.

  9. Quality Assurance Activities in High School Student Mental Health Centers.

    ERIC Educational Resources Information Center

    Nabors, Laura; Tashman, Nancy; Myers, Patrick; Weist, Mark

    This study of school-based mental health programs used stakeholder focus groups to examine factors related to positive treatment outcomes, barriers to accessing services, and methods for improving service delivery to high school students with emotional/behavioral disorders. Fifty-one high school students (34 receiving treatment) at three urban…

  10. What Does Quality Programming Mean for High Achieving Students?

    ERIC Educational Resources Information Center

    Samudzi, Cleo

    2008-01-01

    The Missouri Academy of Science, Mathematics and Computing (Missouri Academy) is a two-year accelerated, early-entrance-to-college, residential school that matches the level, complexity and pace of the curriculum with the readiness and motivation of high achieving high school students. The school is a part of Northwest Missouri State University…

  11. Principles of Quality Controlled Endoscopic Submucosal Dissection with Appropriate Dissection Level and High Quality Resected Specimen

    PubMed Central

    Nishino, Eisei; Man-i, Mariko; East, James E.; Azuma, Takeshi

    2012-01-01

    Endoscopic submucosal dissection (ESD) has enabled en bloc resection of early stage gastrointestinal tumors with negligible risk of lymph node metastasis, regardless of tumor size, location, and shape. However, ESD is a relatively difficult technique compared with conventional endoscopic mucosal resection, requiring a longer procedure time and potentially causing more complications. For safe and reproducible procedure of ESD, the appropriate dissection of the ramified vascular network in the level of middle submucosal layer is required to reach the avascular stratum just above the muscle layer. The horizontal approach to maintain the appropriate depth for dissection beneath the vascular network enables treatment of difficult cases with large vessels and severe fibrosis. The most important aspect of ESD is the precise evaluation of curability. This approach can also secure the quality of the resected specimen with enough depth of the submucosal layer. PMID:23251883

  12. High-quality lossy compression: current and future trends

    NASA Astrophysics Data System (ADS)

    McLaughlin, Steven W.

    1995-01-01

    This paper is concerned with current and future trends in the lossy compression of real sources such as imagery, video, speech and music. We put all lossy compression schemes into common framework where each can be characterized in terms of three well-defined advantages: cell shape, region shape and memory advantages. We concentrate on image compression and discuss how new entropy constrained trellis-based compressors achieve cell- shape, region-shape and memory gain resulting in high fidelity and high compression.

  13. The Common Metadata Repository: A High Performance, High Quality Metadata Engine for Next Generation EOSDIS Applications

    NASA Astrophysics Data System (ADS)

    Pilone, D.; Baynes, K.; Farley, J. D.; Murphy, K. J.; Ritz, S.; Northcutt, R.; Cherry, T. A.; Gokey, C.; Wanchoo, L.

    2013-12-01

    As data archives grow and more data becomes accessible online, cataloging, searching, and extracting relevant data from these archives becomes a critical part of Earth Science research. Current metadata systems such as ECHO, EMS, and GCMD require metadata providers to maintain multiple, disparate systems utilizing different formats and different mechanisms for submitting and updating their entries. As an end user or application developer, this inconsistency reduces the value of the metadata and complicates finding and using earth science data. Building on the results of the ESDIS Metadata Harmony Study of 2012, we completed a Metadata Harmony Study 2 in 2013 to identify specific areas where metadata quality, consistency, and availability could be improved while reducing the burden on metadata providers. In this talk we discuss the results of the Metadata Harmony 2 study and the impacts on the EOSDIS community. Specifically, we'll discuss: - The Unified Metadata Model (UMM) that unifies the ECHO, GCMD, and EMS metadata models - The Common Metadata Repository (CMR) which will provide a high performance common repository for both EOSDIS and non-EOSDIS metadata unifying the ECHO, GCMD, and EMS metadata stores - The CMR's approach to automated metadata assessment and review combined with a dedicated a science support team to significantly improve quality and consistency across Earth Science metadata - Future expandability of the CMR beyond basic science metadata to incorporate multiple metadata concepts including visualization, data attributes, services, documentation, and tool metadata - The CMR's relationship with evolving metadata standards such as work from the MENDS group and ISO19115 NASA Best Practices This talk is targeted at metadata providers, consumers, and Earth Science Data end users to introduce components that will support next generation EOSDIS applications.

  14. Clitoria ternatea L. as a Potential High Quality Forage Legume

    PubMed Central

    Abreu, Matheus Lima Corrêa; Vieira, Ricardo Augusto Mendonça; Rocha, Norberto Silva; Araujo, Raphael Pavesi; Glória, Leonardo Siqueira; Fernandes, Alberto Magno; de Lacerda, Paulo Drude; Júnior, Antonio Gesualdi

    2014-01-01

    Samples of Clitoria ternatea L. (Cunhã) were harvested at 35, 50, 70, and 90 d after a uniformity harvest in a field study designed as a completely randomized design with a total of 18 experimental plots. The dry matter yield of the whole plant was separated quantitatively into leaves, stems, and pods at each harvesting age. Chemical analyses and in vitro gas production kinetics were performed to assess the quality of the plant parts. Yields, chemical composition, and estimates of gas production parameters were analyzed by fitting a mixed statistical model with two types of covariance structures as follows: variance components and an unrestricted structure with heterogeneous variances. Fast and slow gas yielding pools were detected for both leaves and stems, but only a single pool was detected for pods. The homoscedasticity assumption was more likely for all variables, except for some parameters of the gas production kinetics of leaves and stems. There was no presence of typical pods at 35 and 50 d. In the leaves, the fibrous fractions were affected, whereas the non-fibrous fractions were unaffected by the harvesting age. The harvesting age affected the majority of the chemical constituents and gas kinetic parameters related to the stems. The leaves of this legume were the least affected part by the aging process. PMID:25049940

  15. Clitoria ternatea L. as a Potential High Quality Forage Legume.

    PubMed

    Abreu, Matheus Lima Corrêa; Vieira, Ricardo Augusto Mendonça; Rocha, Norberto Silva; Araujo, Raphael Pavesi; Glória, Leonardo Siqueira; Fernandes, Alberto Magno; de Lacerda, Paulo Drude; Júnior, Antonio Gesualdi

    2014-02-01

    Samples of Clitoria ternatea L. (Cunhã) were harvested at 35, 50, 70, and 90 d after a uniformity harvest in a field study designed as a completely randomized design with a total of 18 experimental plots. The dry matter yield of the whole plant was separated quantitatively into leaves, stems, and pods at each harvesting age. Chemical analyses and in vitro gas production kinetics were performed to assess the quality of the plant parts. Yields, chemical composition, and estimates of gas production parameters were analyzed by fitting a mixed statistical model with two types of covariance structures as follows: variance components and an unrestricted structure with heterogeneous variances. Fast and slow gas yielding pools were detected for both leaves and stems, but only a single pool was detected for pods. The homoscedasticity assumption was more likely for all variables, except for some parameters of the gas production kinetics of leaves and stems. There was no presence of typical pods at 35 and 50 d. In the leaves, the fibrous fractions were affected, whereas the non-fibrous fractions were unaffected by the harvesting age. The harvesting age affected the majority of the chemical constituents and gas kinetic parameters related to the stems. The leaves of this legume were the least affected part by the aging process. PMID:25049940

  16. Quality, quality, quality!

    NASA Astrophysics Data System (ADS)

    Aubrey, Charles A., II

    1994-03-01

    The manufacturing base is being revitalized by new manufacturing directions such as the new agile manufacturing and environmentally-conscious manufacturing. These processes hold promise for bringing high-impact technologies to quick commercial fruition, and more than ever before they incorporate quality principles in their development and operation. Because of their pivotal role in all of these aspects, the R&D institutions must maintain a firm grasp on solid quality fundamentals and new developments in the field.

  17. Large-scale high quality glass microlens arrays fabricated by laser enhanced wet etching.

    PubMed

    Tong, Siyu; Bian, Hao; Yang, Qing; Chen, Feng; Deng, Zefang; Si, Jinhai; Hou, Xun

    2014-11-17

    Large-scale high quality microlens arrays (MLAs) play an important role in enhancing the imaging quality of CCD and CMOS as well as the light extraction efficiency of LEDs and OLEDs. To meet the requirement in MLAs' wide application areas, a rapid fabrication method to fabricate large-scale MLAs with high quality, high fill factor and high uniformity is needed, especially on the glass substrate. In this paper, we present a simple and cost-efficient approach to the development of both concave and convex large-scale microlens arrays (MLAs) by using femtosecond laser wet etching method and replication technique. A large-scale high quality square-shaped microlens array with 512 × 512 units was fabricated.The unit size is 20 × 20 μm² on the whole scale of 1 × 1 cm². Its perfect uniformity and optical performance are demonstrated. PMID:25402166

  18. SCALED SIMULATION DESIGN OF HIGH QUALITY LASER WAKEFIELD ACCELERATOR STAGES

    SciTech Connect

    Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.; Bruhwiler, D.L.; Cowan, B.; Nieter, C.; Paul, K.; Cary, J.R.

    2009-05-04

    Design of efficient, high gradient laser driven wakefield accelerator (LWFA) stages using explicit particle-incell simulations with physical parameters scaled by plasma density is presented. LWFAs produce few percent energy spread electron bunches at 0.1-1 GeV with high accelerating gradients. Design tools are now required to predict and improve performance and efficiency of future LWFA stages. Scaling physical parameters extends the reach of explicit simulations to address applications including 10 GeV stages and stages for radiation sources, and accurately resolves deep laser depletion to evaluate efficient stages.

  19. Tapping the Potential: Retaining and Developing High-Quality New Teachers

    ERIC Educational Resources Information Center

    Alliance for Excellent Education, 2010

    2010-01-01

    There is growing consensus that the single most important factor in determining student performance is the quality of the teacher. Therefore, if the national goal of providing an equitable education to children across this nation is to be met, it is critical that efforts be concentrated on developing and retaining high-quality teachers in every…

  20. Relationships of cotton fiber properties to ring-spun yarn quality on selected High Plains cottons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to evaluate the adequacy of High Volume Instruement (HVI) and Advanced Fiber Information System (AFIS) fiber quality parameters for predicting quality parameters of ring-spun yarns considering differences in harvest method. Fiber properties measured using the HVI (...