Science.gov

Sample records for high quality microcavities

  1. Modulation of high quality factors in rolled-up microcavities

    NASA Astrophysics Data System (ADS)

    Fang, Yangfu; Li, Shilong; Mei, Yongfeng

    2016-09-01

    We systematically investigate the evolution of resonant modes in a rolled-up microcavity as the overlap length between structural notches increases, which presents a modulation behavior for high Q factors. The resonant modes in the rolled-up microcavity display a deterministic mode chirality, which is well correlated to the Q factor. We derive a two-mode non-Hermitian Hamiltonian to clarify these unusual findings. It reveals that strong resonant interactions of scattered waves between the structural notches are responsible for the high mode chirality (thus high Q factor) and its modulation behavior in rolled-up microcavities.

  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. Ultra high quality factor one dimensional photonic crystal/photonic wire micro-cavities in silicon-on-insulator (SOI).

    PubMed

    Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

    2008-08-04

    We present experimental results on photonic crystal/photonic wire micro-cavity structures that demonstrate further enhancement of the quality-factor (Q-factor)--up to approximately 149,000--in the fibre telecommunications wavelength range. The Q-values and the useful transmission levels achieved are due, in particular, to the combination of both tapering within and outside the micro-cavity, with carefully designed hole diameters and non-periodic hole placement within the tapered section. Our 2D Finite Difference Time Domain (FDTD) simulation approach shows good agreement with the experimental results.

  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. On-chip three-dimensional high-Q microcavities fabricated by femtosecond laser direct writing.

    PubMed

    Lin, Jintian; Yu, Shangjie; Ma, Yaoguang; Fang, Wei; He, Fei; Qiao, Lingling; Tong, Limin; Cheng, Ya; Xu, Zhizhan

    2012-04-23

    We report on the fabrication of three-dimensional (3D) high-Q whispering gallery microcavities on a fused silica chip by femtosecond laser microfabriction, enabled by the 3D nature of femtosecond laser direct writing. The processing mainly consists of formation of freestanding microdisks by femtosecond laser direct writing and subsequent wet chemical etching. CO(2) laser annealing is followed to smooth the microcavity surface. Microcavities with arbitrary tilting angle, lateral and vertical positioning are demonstrated, and the quality (Q)-factor of a typical microcavity is measured to be up to 1.07 × 10(6), which is currently limited by the low spatial resolution of the motion stage used during the laser patterning and can be improved with motion stages of higher resolutions.

  6. Localized high-Q modes in conical microcavities

    NASA Astrophysics Data System (ADS)

    Lin, Xing; Fang, Wei

    2016-12-01

    We carry out three-dimensional (3D) numerical simulation on a conical microcavity with a half-angle of 11 degree, where there exists high-Q modes by introducing a thin high refractive index film on a conical surface. Our study reveals that, rather than the surface profile of the microcavity, the effective radius plays crucial role in whether the cavity may support localized modes. Specifically, the change of high refractive index film thickness creates an additional angular momentum barrier, so that the conical microcavity may sustain localized high-Q modes. Our study offers a new degree of freedom to control the properties of 3D microcavities, which is useful for microlaser or sensor applications.

  7. The combination of high Q factor and chirality in twin cavities and microcavity chain.

    PubMed

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-09-29

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities.

  8. The combination of high Q factor and chirality in twin cavities and microcavity chain

    PubMed Central

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-01-01

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities. PMID:25262881

  9. Control of lasing from a highly photoexcited semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Hsu, Feng-Kuo

    Technological advances in the fabrication of optical cavities and crystal growth have enabled the studies on macroscopic quantum states and emergent nonequilibrium phenomena of light-matter hybrids in condensed matter. Optical excitations in a semiconductor microcavity can result in a coupled electron-hole-photon (e-h-gamma) system, in which various many-body physics can be studied by varying particle densities and particle-particle interactions. Recently there have been reports of phenomena analogous to Bose-Einstein condensates or superfluids for exciton-polaritons in a microcavity. An exciton-polariton is a quasiparticle resulting from strong coupling between the cavity light field and the exciton (e-h pair) transition, and typically is only stable at a low density ( 10 11 to 1012 cm-2 or less). At a higher density, it has been theoretically predicted that pairing of electrons and holes can result in a BCS-like state at cryogenic temperatures, which can produce cooperative radiation known as superradiance. In this work, we explore cooperative phenomena caused by e-h correlation and many-body effect in a highly photoexcited microcavity at room temperature. High-density e-h plasmas in a photoexcited microcavity are studied under the following conditions: (1) the sample is photoexcited GaAs-based microcavity with large detuning between the band gap Eg of quantum well and cavity resonance to prevent carriers from radiative loss, (2) the density of e-h pairs is high enough to build long-range correlation with the assistance of cavity light field. The Fermi level of electron-hole pairs is about 80 meV above Eg, and (3) the e-h correlation is stabilized through thermal management, which includes modulating the excitation pulse laser temporally and spatially to reduce the heating and carrier diffusion effect. We have observed ultrafast (sub-10 picoseconds) spin-polarized lasing with sizable energy shifts and linewidth broadenings as pump flux is increased. With

  10. Graphene induced high-Q hybridized plasmonic whispering gallery mode microcavities.

    PubMed

    Jiang, Mingming; Li, Jitao; Xu, Chunxiang; Wang, Shuangpeng; Shan, Chongxin; Xuan, Bin; Ning, Yongqiang; Shen, Dezhen

    2014-10-06

    A novel hybridized plasmonic whispering gallery mode (WGM) microcavities composed of graphene monolayer coated ZnO microrod with hexagonal cross section were proposed that operates in the ultraviolet region. π and π + σ surface plasmon modes in graphene monolayer at 4.7 eV and 14.6 eV can be used to achieve the near field coupling interaction between surface plasmonic modes and the conventional WGM microcavity modes in the ultraviolet band. Significantly, the coupling, happened in the evanescent wave field excited along the interface between ZnO and graphene, can lead to distinct optical field confinement and lasing enhancement experimentally, so as well as WGM lasing characteristics, such as the higher cavity quality factor (Q), narrower linewidth, lasing intensities enhancement. The results could provide a platform to study hybridized plasmonic cavity dynamics, and also provides the building blocks to construct graphene based novel microcavity for high performance ultraviolet laser devices with potential application to optical signal processing, biological monitoring, and so on.

  11. Silicon nano-membrane based photonic crystal microcavities for high sensitivity bio-sensing.

    PubMed

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

    2012-04-01

    We experimentally demonstrated photonic crystal microcavity based resonant sensors coupled to photonic crystal waveguides in silicon nano-membrane on insulator for chemical and bio-sensing. Linear L-type microcavities are considered. In contrast to cavities with small mode volumes, but low quality factors for bio-sensing, we showed increasing the length of the microcavity enhances the quality factor of the resonance by an order of magnitude and increases the resonance wavelength shift while retaining compact device characteristics. Q~26760 and sensitivity down to 15 ng/ml and ~110 pg/mm2 in bio-sensing was experimentally demonstrated on silicon-on-insulator devices.

  12. Silicon nano-membrane based photonic crystal microcavities for high sensitivity bio-sensing

    PubMed Central

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

    2012-01-01

    We experimentally demonstrated photonic crystal microcavity based resonant sensors coupled to photonic crystal waveguides in silicon nano-membrane on insulator for chemical and bio-sensing. Linear L-type microcavities are considered. In contrast to cavities with small mode volumes, but low quality factors for bio-sensing, we showed increasing the length of the microcavity enhances the quality factor of the resonance by an order of magnitude and increases the resonance wavelength shift while retaining compact device characteristics. Q~26760 and sensitivity down to 15 ng/ml and~110 pg/mm2 in bio-sensing was experimentally demonstrated on silicon-on-insulator devices. PMID:22466197

  13. Ringing phenomenon in chaotic microcavity for high-speed ultra-sensitive sensing

    PubMed Central

    Chen, Lei; Liu, Qian; Zhang, Wei-Gang; Chou, Keng C.

    2016-01-01

    The ringing phenomenon in whispering-gallery-mode (WGM) microcavities has demonstrated its great potential for highly-sensitive and high-speed sensing. However, traditional symmetric WGM microcavities have suffered from an extremely low coupling efficiency via free-space coupling because the emission of symmetric WGMs is non-directional. Here we report a new approach for high-speed ultra-sensitive sensing using the ringing phenomenon in a chaotic regime. By breaking the rotational symmetry of a WGM microcavity and introducing chaotic behaviors, we show that the ringing phenomenon in chaotic WGM microcavities extends over both the positive and the negative frequency detune, allowing the ringing phenomenon to interact with analytes over a much broader bandwidth with a reduced dead time. Because the coupling of the chaotic microcavity is directional, it produces a significantly higher signal output, which improves its sensitivity without the need of a fiber coupler. PMID:27966591

  14. 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.

  15. 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.

  16. Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure.

    PubMed

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

    2014-08-07

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  18. 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.

  19. High-sensitivity polarization modulation reflectance spectroscopy of cavity polaritons in a ZnO microcavity

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takayuki; Kishimoto, Ryo; Takagi, Yoshihiro; Kawase, Toshiki; Kim, DaeGwi; Nakayama, Masaaki

    2014-03-01

    We report that polarization modulation reflectance (PMR) spectroscopy is highly sensitive to the cavity polaritons in a ZnO microcavity with HfO2/SiO2 distributed Bragg reflectors. We demonstrate that the cavity-polariton dispersion, even in the energy region of strong absorption by exciton continuum states, is clearly observed by PMR spectroscopy. The PMR spectra were quantitatively analyzed by a transfer-matrix method taking into account three types of excitons labeled A, B, and C. Line-shape analysis of the PMR spectra indicates that the anisotropy of the excitonic transitions is considerable in treating the cavity polariton in the ZnO microcavity.

  20. 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.

  1. Enhancing microcavity polaritons for technological applications

    NASA Astrophysics Data System (ADS)

    Steger, Mark D.

    Microcavity exciton-polaritons, semiconductor quasiparticles that are a unique mixture of light and matter, are routinely used to study quantum many-body phenomena. Due to the light mass of the polariton, 10 -4 times the bare electron mass, polaritons manifest noticeable quantum effects even at room temperature. As solid state systems, microcavity polaritons are generally robust and compatible with current semiconductor technology. Microcavity chips could be integrated into electronic or optical circuits. I present a demonstration of microcavity polaritons as an all-optical transistor, where the strong nonlinearity of the system leads to a change in the re ectivity for a signal light-ray from high to low. I also discuss the promise of using strongly coupled microcavities as low-threshold polariton lasers, which could replace traditional lasers in some cases. The last two decades have seen great strides in the material systems used in microcavities, even demonstrating strong coupling at room temperature. GaN, CdZnSe, organic semiconductors and more recently, MoS2 have supported strong coupling at ambient conditions. This makes technological applications more promising. I present our current progress in this field. Also, the general quality of microcavities has advanced steadily over this time. I demonstrate that our long-lifetime polaritons persist for an order of magnitude longer than in similar samples. This opens up new regimes of study and technological application as these particles thermalize better and carry quantum coherence over macroscopic distances.

  2. 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

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

    PubMed

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

    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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  6. Harmonic mode locking in a high-Q whispering gallery mode microcavity

    NASA Astrophysics Data System (ADS)

    Tanabe, Takasumi; Kato, Takumi; Kobatake, Tomoya; Suzuki, Ryo; Chen-Jinnai, Akitoshi

    2016-03-01

    We present a numerical and experimental study of the generation of harmonic mode locking in a silica toroid microcavity. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We found that a stable harmonic mode-locking regime can be accessed when we reduce the input power after strong pumping even if we do not carefully adjust the wavelength detuning. This is due to the bistable nature of the nonlinear cavity system. The experiment agrees well with the numerical analysis, where we obtain a low-noise Kerr comb spectrum with a narrow longitudinal mode spacing by gradually reducing the input pump power after strong pumping. This finding clarifies the procedure for generating harmonic mode locking in such high-Q microcavity systems.

  7. 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.

  8. High Q-factor colloidal nanocrystal-based vertical microcavity by hot embossing technology

    NASA Astrophysics Data System (ADS)

    Martiradonna, Luigi; Carbone, Luigi; De Giorgi, Milena; Manna, Liberato; Gigli, Giuseppe; Cingolani, Roberto; De Vittorio, Massimo

    2006-05-01

    We report on the fabrication and optical characterization of vertical hybrid microcavities in which a layer of colloidal nanocrystals dispersed in an organic matrix is embedded between two inorganic mirrors. The devices are fabricated by a technique based on the unconventional use of the hot embossing technology, which allows a very fine control of the cavity length. The technique exploits a λ-thick microstructured dielectric top mirror pressed onto the bottom one, previously coated with the active layer, to sandwich the cavity and precisely control its thickness. Room-temperature photoluminescence measurements show a Q factor as high as 146 for our devices.

  9. 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.

  10. Optical microcavity: sensing down to single molecules and atoms.

    PubMed

    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.

  11. Self-sustained photothermal oscillations in high-finesse Fabry-Perot microcavities

    NASA Astrophysics Data System (ADS)

    Konthasinghe, Kumarasiri; Velez, Juan Gomez; Hopkins, Adam J.; Peiris, Manoj; Profeta, Luisa T. M.; Nieves, Yamil; Muller, Andreas

    2017-01-01

    We report the experimental investigation of a regime of microscopic Fabry-Perot resonators in which competing light-induced forces—photothermal expansion and photothermal refraction—acting oppositely and on different timescales lead to self-sustained persistent oscillations. Previously concealed as ordinary thermo-optic bistability—a common feature in low-loss resonator physics—these dynamics are visible as fast pulsations in cavity transmission or reflection measurements at sufficiently high time resolution. Their underlying mathematical description is shared by many slow-fast phenomena in chemistry, biology, and neuroscience. Our observations are relevant in particular to microcavity applications in atom optics and cavity quantum electrodynamics, even in nominally rigid structures that have not undergone lithography.

  12. 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

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

    PubMed

    Vollmer, Frank; Yang, Lan

    2012-12-01

    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.

  14. Hybrid plasmonic microcavity with an air-filled gap for sensing applications

    NASA Astrophysics Data System (ADS)

    Zhang, Meng; Liu, Binbin; Wu, Genzhu; Chen, Daru

    2016-12-01

    In this paper, a novel hybrid plasmonic microcavity with air-filled regions in the low-permittivity dielectric gap is proposed for sensing applications. Compared with the conventional structure with homogeneous gap, the introduced air-filled regions could improve the key modal characteristics of the hybrid mode. Simulation results reveal that this kind of hybrid microcavity maintains low loss with high quality factor ∼3062, and high field confinement with small mode volume 0.891 μm3. Moreover, in the sensing applications, this hybrid microcavity features simultaneously large refractive index sensitivity of 100 nm/RIU (refractive index unit) and relatively high quality factor of 3062. Hence, it shows that the hybrid plasmonic microcavity has potential applications in ultra-compact refractive index sensor.

  15. 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

    2014-09-11

    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.

  16. 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.

  17. Microcavity Laser Based on a Single Molecule Thick High Gain Layer.

    PubMed

    Palatnik, Alexander; Aviv, Hagit; Tischler, Yaakov R

    2017-04-05

    The ability to confine excitons within monolayers has led to fundamental investigations of non-radiative energy transfer, super-radiance, strong light-matter coupling, high-efficiency LEDs, and recently lasers in lateral resonator architectures. Vertical Cavity Surface Emitting Lasers (VCSELs), in which lasing occurs perpendicular to the device plane, are critical for telecommunications and large-scale photonics integration, however strong optical self-absorption and low fluorescence quantum yields have thus far prevented coherent emission from a monolayer microcavity device. Here we show lasing from a monolayer VCSEL using a single molecule thick film of amphiphilic fluorescent dye, assembled via Langmuir-Blodgett deposition, as the gain layer. Threshold was observed when 5% of the molecules were excited (4.4 μJ/cm(2)). At this level of excitation, the optical gain in the monolayer exceeds 1056 cm(-1). High localization of the excitons in the VCSEL gain layer can enhance their collective emission properties with Langmuir-Blodgett deposition presenting a paradigm for engineering the high gain layers on the molecular level.

  18. Glass-based 1-D dielectric microcavities

    NASA Astrophysics Data System (ADS)

    Chiasera, Alessandro; Scotognella, Francesco; Valligatla, Sreeramulu; Varas, Stefano; Jasieniak, Jacek; Criante, Luigino; Lukowiak, Anna; Ristic, Davor; Gonçalves, Rogeria Rocha; Taccheo, Stefano; Ivanda, Mile; Righini, Giancarlo C.; Ramponi, Roberta; Martucci, Alessandro; Ferrari, Maurizio

    2016-11-01

    We have developed a reliable RF sputtering techniques allowing to fabricate glass-based one dimensional microcavities, with high quality factor. This property is strongly related to the modification of the density of states due to the confinement of the gain medium in a photonic band gap structure. In this short review we present some of the more recent results obtained by our team exploiting these 1D microcavities. In particular we present: (1) Er3+ luminescence enhancement of the 4I13/2 → 4I15/2 transition; (2) broad band filters based on disordered 1-D photonic structures; (3) threshold defect-mode lasing action in a hybrid structure.

  19. Microcavity Enhanced Raman Scattering

    NASA Astrophysics Data System (ADS)

    Petrak, Benjamin J.

    Raman scattering can accurately identify molecules by their intrinsic vibrational frequencies, but its notoriously weak scattering efficiency for gases presents a major obstacle to its practical application in gas sensing and analysis. This work explores the use of high finesse (≈50 000) Fabry-Perot microcavities as a means to enhance Raman scattering from gases. A recently demonstrated laser ablation method, which carves out a micromirror template on fused silica--either on a fiber tip or bulk substrates-- was implemented, characterized, and optimized to fabricate concave micromirror templates ˜10 mum diameter and radius of curvature. The fabricated templates were coated with a high-reflectivity dielectric coating by ion-beam sputtering and were assembled into microcavities ˜10 mum long and with a mode volume ˜100 mum 3. A novel gas sensing technique that we refer to as Purcell enhanced Raman scattering (PERS) was demonstrated using the assembled microcavities. PERS works by enhancing the pump laser's intensity through resonant recirculation at one longitudinal mode, while simultaneously, at a second mode at the Stokes frequency, the Purcell effect increases the rate of spontaneous Raman scattering by a change to the intra-cavity photon density of states. PERS was shown to enhance the rate of spontaneous Raman scattering by a factor of 107 compared to the same volume of sample gas in free space scattered into the same solid angle subtended by the cavity. PERS was also shown capable of resolving several Raman bands from different isotopes of CO2 gas for application to isotopic analysis. Finally, the use of the microcavity to enhance coherent anti-Stokes Raman scattering (CARS) from CO2 gas was demonstrated.

  20. Strong photocurrent enhancements in highly efficient flexible organic solar cells by adopting a microcavity configuration.

    PubMed

    Chen, Kung-Shih; Yip, Hin-Lap; Salinas, José-Francisco; Xu, Yun-Xiang; Chueh, Chu-Chen; Jen, Alex K-Y

    2014-05-28

    Organic solar cells often show inefficient light harvesting due to a short absorption path length limited by the low charge mobility of organic semiconductors. We demonstrate a flexible organic solar cell in a microcavity configuration using a TeO2/Ag semitransparent electrode to confine the optical field within the device with significant performance improvements and reaching a power conversion efficiency of 8.56%.

  1. On-chip asymmetric microcavity optomechanics.

    PubMed

    Soltani, Soheil; Hudnut, Alexa W; Armani, Andrea M

    2016-12-26

    High quality factor (Q) optical resonators have enabled rapid growth in the field of cavity-enhanced, radiation pressure-induced optomechanics. However, because research has focused on axisymmetric devices, the observed regenerative excited mechanical modes are similar. In the present work, a strategy for fabricating high-Q whispering gallery mode microcavities with varying degrees of asymmetry is developed and demonstrated. Due to the combination of high optical Q and asymmetric device design, two previously unobserved modes, the asymmetric cantilever and asymmetric crown mode, are demonstrated with sub-mW thresholds for onset of oscillations. The experimental results are in good agreement with computational modeling predictions.

  2. Fabrication of directional nanopillars with high-aspect-ratio using a stretching imprint process with a microcavity mold.

    PubMed

    Jiang, Weitao; Lei, Biao; Liu, Hongzhong; Niu, Dong; Zhao, Tingting; Chen, Bangdao; Yin, Lei; Shi, Yongsheng; Liu, Xiaokang

    2017-02-09

    Directional nanopillars with high-aspect-ratio have wide applications in home or industrial appliances and biomimetic robots. Their fabrication, however, is a challenge for conventional methods. In this study, we propose a simple stretching imprint process to prepare controllable directional (30°-90° in a slanted angle) nanopillars (200-800 nm in diameter) with high aspect ratio (>30) using a microcavity mold, beyond the conventional nanoimprint process, for 1 : 1 pattern transfer from the mold to the replica. The mechanism of the stretching imprint process is further investigated, and a rheology model for the filament evolution during the stretching process is established, which clearly shows that the aspect-ratio, diameter in submicrons, slanted angle, and also the tip profile of the free-standing nanopillars can be easily controlled by the imprint process using a microcavity mold. Further experiments indicate that the fabricated directional free-standing nanopillars show strong friction anisotropy, which may find applications in biomimetic studies.

  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. Enhanced nonlinear interaction in a microcavity under coherent excitation.

    PubMed

    Serna, Samuel; Oden, Jérèmy; Hanna, Marc; Caer, Charles; Le Roux, Xavier; Sauvan, Christophe; Delaye, Philippe; Cassan, Eric; Dubreuil, Nicolas

    2015-11-16

    The large field enhancement that can be achieved in high quality factor and small mode volume photonic crystal microcavities leads to strengthened nonlinear interactions. However, the frequency shift dynamics of the cavity resonance under a pulsed excitation, which is driven by nonlinear refractive index change, tends to limit the coupling efficiency between the pulse and the cavity. As a consequence, the cavity enhancement effect cannot last for the entire pulse duration, limiting the interaction between the pulse and the intra-cavity material. In order to preserve the benefit of light localization throughout the pulsed excitation, we report the first experimental demonstration of coherent excitation of a nonlinear microcavity, leading to an enhanced intra-cavity nonlinear interaction. We investigate the nonlinear behavior of a Silicon-based microcavity subject to tailored positively chirped pulses, enabling to increase the free carrier density generated by two-photon absorption by up to a factor of 2.5 compared with a Fourier-transform limited pulse excitation of equal energy. It is accompanied by an extended frequency blue-shift of the cavity resonance reaching 19 times the linear cavity bandwidth. This experimental result highlights the interest in using coherent excitation to control intra-cavity light-matter interactions and nonlinear dynamics of microcavity-based optical devices.

  6. Quantum well nonlinear microcavities

    NASA Astrophysics Data System (ADS)

    Oudar, J. L.; Kuszelewicz, R.; Sfez, B.; Pellat, D.; Azoulay, R.

    We report on recent progress in reducing the power threshold of all-optical bistable quantum well vertical microcavities. Significant improvements are achieved through an increase of the cavity finesse, together with a reduction of the device active layer thickness. A critical intensity of 5 μW/μm 2 has been observed on a microcavity of finesse 250, with a nonlinear medium of only 18 GaAs quantum wells of 10 nm thickness. Further improvements of the Bragg mirror quality resulted in a finesse of 700 and a power-lifetime product of 15 fJ/μm 2. Microresonator pixellation allows to obtain 2-dimensional arrays. A thermally-induced alloy-mixing technique is described, which produced a 110 meV carrier confinement energy, together with a refractive index change of -.012, averaged over the 2.6 μm nonlinear medium thickness. The resulting electrical and optical confinement is shown to improve the nonlinear characteristics, by limiting lateral carrier diffusion and light diffraction.

  7. Highly efficient phosphor-converted white organic light-emitting diodes with moderate microcavity and light-recycling filters.

    PubMed

    Cho, Sang-Hwan; Oh, Jeong Rok; Park, Hoo Keun; Kim, Hyoung Kun; Lee, Yong-Hee; Lee, Jae-Gab; Do, Young Rag

    2010-01-18

    We demonstrate the combined effects of a microcavity structure and light-recycling filters (LRFs) on the forward electrical efficiency of phosphor-converted white organic light-emitting diodes (pc-WOLEDs). The introduction of a single pair of low- and high-index layers (SiO(2)/TiO(2)) improves the blue emission from blue OLED and the insertion of blue-passing and yellow-reflecting LRFs enhances the forward yellow emission from the YAG:Ce(3+) phosphors layers. The enhancement of the luminous efficacy of the forward white emission is 1.92 times that of a conventional pc-WOLED with color coordinates of (0.34, 0.34) and a correlated color temperature of about 4800 K.

  8. Mode control and direct modulation for waveguide-coupled square microcavity lasers

    NASA Astrophysics Data System (ADS)

    Yang, Yue-De; Xiao, Zhi-Xiong; Weng, Hai-Zhong; Xiao, Jin-Long; Huang, Yong-Zhen

    2016-11-01

    Lasing mode control and direct modulation characteristics have been investigated for waveguide-coupled unidirectional-emission square microcavity lasers. A quasi-analytical model is introduced to analyze the mode field distributions and quality (Q) factors for the confined modes inside the square optical microcavities with directly coupled waveguide, where high-Q whispering-gallery-like (WG-like) modes are induced by the mode coupling between doubly-degenerate modes. AlGaInAs/InP waveguide-coupled unidirectional-emission square microcavity lasers are fabricated by using standard planar technology, and electrically-injected lasing is realized at room temperature. The lasing modes are controlled by properly designing the lasing cavity, output waveguide and injection pattern. Dual-transverse-mode lasing with a tunable wavelength interval from 0.25 to 0.39 nm is realized by using a spatially selective current injection to modulate the refractive index, as the mode field distributions of different transverse are spatially separated. The wavelength interval can be further increased to a few nanometers by reducing the cavity size and replacing the flat sidewalls with circular arcs. The field distributions of WG-like modes distribute uniformly in square microcavity, which avoid the burning-induced carrier diffusion in high-speed direct modulation. A small-signal modulation 3dB bandwidth exceeding 16 GHz, and an open eye diagram at 25 Gb/s are demonstrated for the high-speed direct modulated square microcavity laser.

  9. HIgh-Q Optical Micro-cavity Resonators as High Sensitive Bio-chemical and Ultrasonic Sensors

    NASA Astrophysics Data System (ADS)

    Ling, Tao

    Optical micro-cavity resonators have quickly emerged in the past few years as a new sensing platform in a wide range of applications, such as bio-chemical molecular detection, environmental monitoring, acoustic and electromagnetic waves detection. In this thesis, we will mainly focus on developing high sensitivity silica micro-tube resonator bio-chemical sensors and high sensitivity polymer micro-ring resonator acoustic sensors. In high sensitivity silica micro-tube resonator bio-chemical sensors part: We first demonstrated a prism coupled silica micro-tube bio-chemical sensing platform to overcome the reliability problem in a fiber coupled thin wall silica micro-tube sensing platform. In refractive index sensing experiment, a unique resonance mode with sensitivity around 600nm/refractive index unit (RIU) has been observed. Surface sensing experiments also have been performed in this platform to detect lipid monolayer, lipid bilayer, electrostatic self assemble layer-by-layer as well as the interaction between the lipid bilayer and proteins. Then a theoretical study on various sensing properties on the silica micro-tube based sensing platform has been realized. Furthermore, we have proposed a coupled cavity system to further enhance the device's sensitivity above 1000nm/RIU. In high sensitivity polymer micro-ring resonator acoustic sensors part: We first presented a simplified fabrication process and realized a polymer microring with a Q factor around 6000. The fabricated device has been used to detect acoustic wave with noise equivalent pressure (NEP) around 230Pa over 1-75MHz frequency rang, which is comparable to state-of-art piezoelectric transducer and the device's frequency response also have been characterized to be up to 90MHz. A new fabrication process combined with resist reflow and thermal oxidation process has been used to improve the Q factor up to 10 5 and the device's NEP has been tested to be around 88Pa over 1-75MHz range. Further improving the

  10. Spheroidal Fabry-Perot microcavities in optical fibers for high-sensitivity sensing.

    PubMed

    Favero, F C; Araujo, L; Bouwmans, G; Finazzi, V; Villatoro, J; Pruneri, V

    2012-03-26

    All-optical-fiber Fabry-Perot interferometers (FPIs) with microcavities of different shapes were investigated. It was found that the size and shape of the cavity plays an important role on the performance of these interferometers. To corroborate the analysis, FPIs with spheroidal cavities were fabricated by splicing a photonic crystal fiber (PCF) with large voids and a conventional single mode fiber (SMF), using an ad hoc splicing program. It was found that the strain sensitivity of FPIs with spheroidal cavities can be controlled through the dimensions of the spheroid. For example, a FPI whose cavity had a size of ~10x60 μm exhibited strain sensitivity of ~10.3 pm/με and fringe contrast of ~38 dB. Such strain sensitivity is ~10 times larger than that of the popular fiber Bragg gratings (~1.2 pm/με) and higher than that of most low-finesse FPIs. The thermal sensitivity of our FPIs is extremely low (~1pm/°C) due to the air cavities. Thus, a number of temperature-independent ultra-sensitive microscopic sensors can be devised with the interferometers here proposed since many parameters can be converted to strain. To this end, simple vibration sensors are demonstrated.

  11. Patch antenna microcavity terahertz sources with enhanced emission

    NASA Astrophysics Data System (ADS)

    Madéo, J.; Todorov, Y.; Gilman, A.; Frucci, G.; Li, L. H.; Davies, A. G.; Linfield, E. H.; Sirtori, C.; Dani, K. M.

    2016-10-01

    We study the emission properties of an electroluminescent THz frequency quantum cascade structure embedded in an array of patch antenna double-metal microcavities. We show that high photon extraction efficiencies can be obtained by adjusting the active region thickness and array periodicity as well as high Purcell factors (up to 65), leading to an enhanced overall emitted power. Up to a 44-fold increase in power is experimentally observed in comparison with a reference device processed in conventional mesa geometry. Estimation of the Purcell factors using electromagnetic simulations and the theoretical extraction efficiency are in agreement with the observed power enhancement and show that, in these microcavities, the overall enhancement solely depends on the square of the total quality factor.

  12. High Sensitivity Detection of CdSe/ZnS Quantum Dot-Labeled DNA Based on N-type Porous Silicon Microcavities

    PubMed Central

    Lv, Changwu; Jia, Zhenhong; Lv, Jie; Zhang, Hongyan; Li, Yanyu

    2017-01-01

    N-type macroporous silicon microcavity structures were prepared using electrochemical etching in an HF solution in the absence of light and oxidants. The CdSe/ZnS water-soluble quantum dot-labeled DNA target molecules were detected by monitoring the microcavity reflectance spectrum, which was characterized by the reflectance spectrum defect state position shift resulting from changes to the structures’ refractive index. Quantum dots with a high refractive index and DNA coupling can improve the detection sensitivity by amplifying the optical response signals of the target DNA. The experimental results show that DNA combined with a quantum dot can improve the sensitivity of DNA detection by more than five times. PMID:28045442

  13. 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.

  14. 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.

  15. 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%.

  16. Lasing from all-polymer microcavities

    NASA Astrophysics Data System (ADS)

    Canazza, G.; Scotognella, F.; Lanzani, G.; De Silvestri, S.; Zavelani-Rossi, M.; Comoretto, D.

    2014-03-01

    We report on the laser action in a microcavity where both the dielectric mirrors and the active material have a macromolecular nature, resulting in a full plastic laser device. Distributed Bragg reflectors (DBRs) are prepared by spin-coating of polyvinylcarbazole and cellulose acetate orthogonal solutions and the active layer consists of a highly fluorescent conjugated polymer poly(9,9-dioctylfluorenyl-2,7-diyl-co-1,4-benzo-(2,1‧-3)-thiadiazole) (F8BT) spun film. A quality factor in the range 80-180 is achieved and the cavity mode is carefully tuned on the peak of the F8BT amplified spontaneous emission spectrum. Under pulsed optical pumping, laser emission is obtained with a surprisingly low lasing threshold (<20 μJ cm-2) for a full plastic DBR optical cavity. This result opens a simple and cheap way to obtain a new class of polymer lasers.

  17. 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

  18. IMI long-range surface plasmon Bragg micro-cavity

    NASA Astrophysics Data System (ADS)

    Tong, Kai; Wang, Jun; Zhou, Chunliang; Wang, Meiting

    2016-10-01

    The defect layer is introduced to the insulator-metal-insulator (IMI) Bragg waveguide structure. The micro-cavity structure of long-range surface plasma is proposed based on the defect mode. The liquid crystal is the defect layer in the structure of Bragg. The energy band characteristics of the long-range surface plasmon Bragg micro-cavity structure are analyzed by using the finite difference time domain method. The influence of the period number and the length of the micro-cavity on the quality factor Q and the volume V of the Bragg grating are discussed. The results show that the photonic energy can be confined very well in the micro-cavity by the structure of the micro-cavity. By controlling the birefringence of liquid crystal, the resonance wavelength of the micro-cavity appears with redshift phenomenon. The tuning range is 42 nm. The tuning of the working window of the long-range surface plasmon filter is realized. The photonic energy is the strongest in the insulating layer and the metal interface. The increase of cycles number has certain limitation on the improvement of the quality factor Q of the cavity. The influence of the defect-cavity length on the resonant wavelength, the quality factor Q and the mode volume V is obvious. The performance of the micro-cavity can be improved by adjusting the number of the micro-cavity and the length of the defect-cavity, and the ratio of Q/V can reach 43,750 in the communication band. The nano micro-cavity provides a new design idea and basis for the fabrication of tunable long-range surface plasmon wave filter in this paper.

  19. Brillouin Optomechanics in Coupled Silicon Microcavities

    PubMed Central

    Espinel, Y. A. V.; Santos, F. G. S.; Luiz, G. O.; Alegre, T. P. Mayer; Wiederhecker, G. S.

    2017-01-01

    The simultaneous control of optical and mechanical waves has enabled a range of fundamental and technological breakthroughs, from the demonstration of ultra-stable frequency reference devices, to the exploration of the quantum-classical boundaries in optomechanical laser-cooling experiments. More recently, such an optomechanical interaction has been observed in integrated nano-waveguides and microcavities in the Brillouin regime, where short-wavelength mechanical modes scatter light at several GHz. Here we engineer coupled optical microcavities to enable a low threshold excitation of mechanical travelling-wave modes through backward stimulated Brillouin scattering. Exploring the backward scattering we propose silicon microcavity designs based on laterally coupled single and double-layer cavities, the proposed structures enable optomechanical coupling with very high frequency modes (11 to 25 GHz) and large optomechanical coupling rates (g0/2π) from 50 kHz to 90 kHz. PMID:28262814

  20. Brillouin Optomechanics in Coupled Silicon Microcavities

    NASA Astrophysics Data System (ADS)

    Espinel, Y. A. V.; Santos, F. G. S.; Luiz, G. O.; Alegre, T. P. Mayer; Wiederhecker, G. S.

    2017-03-01

    The simultaneous control of optical and mechanical waves has enabled a range of fundamental and technological breakthroughs, from the demonstration of ultra-stable frequency reference devices, to the exploration of the quantum-classical boundaries in optomechanical laser-cooling experiments. More recently, such an optomechanical interaction has been observed in integrated nano-waveguides and microcavities in the Brillouin regime, where short-wavelength mechanical modes scatter light at several GHz. Here we engineer coupled optical microcavities to enable a low threshold excitation of mechanical travelling-wave modes through backward stimulated Brillouin scattering. Exploring the backward scattering we propose silicon microcavity designs based on laterally coupled single and double-layer cavities, the proposed structures enable optomechanical coupling with very high frequency modes (11 to 25 GHz) and large optomechanical coupling rates (g0/2π) from 50 kHz to 90 kHz.

  1. 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.

  2. 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.

  3. Elastomer based electrically tunable, optical microcavities

    NASA Astrophysics Data System (ADS)

    Slowik, Irma; Kronenberg, Nils M.; Franke, Markus; Fischer, Axel; Richter, Andreas; Gather, Malte C.; Leo, Karl

    2016-10-01

    Tunable optical elements are mostly realized by microelectromechanical systems, which require expensive and complex lithography during processing. We demonstrate an alternative device based on an electrically tunable microcavity employing a dielectric soft elastomer actuator. The cavity resonance is varied by changing the physical cavity thickness due to electrostriction of the soft elastomer. We realize a tunable metal-elastomer-distributed Bragg reflector multi-half wavelength microcavity with a cavity layer thickness around 12 μm and quality factors up to 700. Applying a voltage up to 60 V between bottom ITO and top metal electrode tunes the wavelength of the cavity modes up to Δ λ = 14 nm, which relates to a cavity thickness change of about 200 nm. This concept allows the implementation of tunable optical elements like tunable filters or resonators with low cost and simple processing.

  4. 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.

  5. Optical properties of semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Son, Joong-Kon

    Thanks to the difference in energy gap between two semiconductors and to their different indices of refraction, semiconductor heterostructures can confine electrons as well as photons. This property makes it possible to build semiconductor-based optical resonators (microcavities) with a radiation dipole (a quantum well) in its midst to investigate the coupling between the optical modes of the microcavity with the exciton modes of the quantum well. Such an interaction, besides its intrinsic interest, is relevant to vertically-emitting semiconductor lasers, based on the quantum well- microcavity system. In this thesis, we will present experimental evidence of temperature and electric-field dependent exciton-cavity coupling in GaAs-GaAlAs microcavities.

  6. 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.

  7. The micro-cavity of the two dimensional plasmonic photonic crystal

    NASA Astrophysics Data System (ADS)

    Tong, Kai; Zhang, Zhenguo; Yang, Qing

    2015-02-01

    In this manuscript, we proposed a novel and effective two dimensional hybrid plasmonic photonic crystal micro-cavity structure to confine the surface plasmon to a sub-wavelength scale mode volume and obtain a relatively high quality factor. By introducing a single-cell defect at the two dimensional triangular lattice photonic crystal layer, the defect cavity has been established to provide sub-wavelength scale plasmonic mode localization within the hybrid plasmonic photonic crystal structure TM band gap. Comprehensive analysis methods of three-dimensional finite difference time domain method (3D-FDTD) have been used to analyze the characteristics of the micro-cavity of this hybrid structure, including the effects of the radius of the nearest neighbor air holes around the defect, the cavity length of the defect and the thickness of the gain medium on the features of the micro-cavity. By using a quantum dots (QDs)-polymer as a gain medium for the low index thin layer, a gain threshold as low as gth = 534 cm-1 can be achieved with such structures, and deep sub-wavelength mode volume of 0.00201 (λ/n)3 is also obtained.

  8. 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.

  9. 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.

  10. 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.

  11. Extremely sub-wavelength THz metal-dielectric wire microcavities.

    PubMed

    Feuillet-Palma, Cheryl; Todorov, Yanko; Steed, Robert; Vasanelli, Angela; Biasiol, Giorgio; Sorba, Lucia; Sirtori, Carlo

    2012-12-17

    We demonstrate minimal volume wire THz metal-dielectric micro-cavities, in which all but one dimension have been reduced to highly sub-wavelength values. The smallest cavity features an effective volume of 0.4 µm(3), which is ~5.10(-7) times the volume defined by the resonant vacuum wavelength (λ = 94 µm) to the cube. When combined with a doped multi-quantum well structure, such micro-cavities enter the ultra-strong light matter coupling regime, even if the total number of electrons participating to the coupling is only in the order of 10(4), thus much less than in previous studies.

  12. 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.

  13. 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.

  14. Dressing plasmon resonance with particle-microcavity architecture for efficient nano-optical trapping and sensing.

    PubMed

    Zhang, Haixi; Zhou, Yanyan; Yu, Xia; Luan, Feng; Xu, Jianbin; Ong, Hock-Chun; Ho, Ho-Pui

    2014-02-15

    We propose a particle-microcavity scheme for efficient optical trapping and sensing. When a resonant plasmonic nanoparticle (NP) is placed inside a microcavity with high Q-factor, sensitivity is enhanced in the far-field extinction while near-field around the NP is barely affected. Stable near-field and high sensitivity for optical trapping and ultrasensitive detection of nanosized targets are therefore realized simultaneously. Such a particle-microcavity system opens up a new hybrid nanophotonic device platform that combines the unique merits of conventional and plasmonic integrated photonics.

  15. 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.

  16. Transport Mechanisms in Dielectric Optical Microcavities

    NASA Astrophysics Data System (ADS)

    Painchaud-April, G.; Poirier, J.; Dubé, L. J.

    2008-05-01

    Optical 2D microcavities have become a source of promising new technologies over the last decades. Applications ranging from high accuracy spectrometry to laser design will benefit from the development of such devices. The versatility of the concept resides in the ray-wave correspondence [1, 2]: the short wavelength limit of the system exhibits properties of well-known billiard systems, which may include Hamiltonian chaos. Therefore, since the wave behaviour of an optical microcavity is influenced by the underlying phase-space structure, a study and characterization of this structure becomes important to predict where the electromagnetic energy will flow out of the cavity. Whereas the correspondence works reasonably well for regular (classically integrable) and completely chaotic systems, partially chaotic systems of mixed phase space show transport properties largely influenced by tunnelling and localization effects with the consequence that the correspondence is all but lost. We will present the results of our investigations, in the ray and wave dynamics, in order to shed some light on the collaborating influence of the different transport mechanisms. [1] H. G. L. Schwefel et al., J. Opt. Soc. Am. B21, 923--934 (2004). [2] J. Wiersig and M. Hentschel, Phys. Rev. Lett, 100, 033901 (2008).

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Pixel-level plasmonic microcavity infrared photodetector

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  2. 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

  3. Photothermal effects in ultra-precisely stabilized tunable microcavities

    NASA Astrophysics Data System (ADS)

    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 $1.1 \\times 10^{-13}\\,$m rms.

  4. Nonlinear magneto-optic quantum microcavity

    NASA Astrophysics Data System (ADS)

    Frey, Robert; Andre, Regis; Flytzanis, Christos

    2002-05-01

    The study of the linear, nonlinear, and photo-induced behavior in a magneto-optic micro-cavity in the strong coupling regime is investigated using the reflectivity and magneto-optic Kerr rotation techniques. The photo-induced modifications of the strong coupling regime are traced to the light induced changes of the exciton transition by many body interactions and band filling effects. At a fluence of 1 (mu) J/cm-2 the saturation and blue shift of the quantum well exciton transition produce strong modifications of the lower polariton frequency which induce nonlinear magneto-optic Kerr rotations of 30 degrees at a magnetic field amplitude of 0.2 Tesla. With no applied magnetic field polarization rotations of more than 10 degrees are photo- induced by 1 (mu) J/cm-2 fluence circularly polarized pump pulses. Such a physical effect could be interesting for high contrast fast optical signal processing when room temperature operation becomes available.

  5. Multivalley engineering in semiconductor microcavities.

    PubMed

    Sun, M; Savenko, I G; Flayac, H; Liew, T C H

    2017-04-03

    We consider exciton-photon coupling in semiconductor microcavities in which separate periodic potentials have been embedded for excitons and photons. We show theoretically that this system supports degenerate ground-states appearing at non-zero inplane momenta, corresponding to multiple valleys in reciprocal space, which are further separated in polarization corresponding to a polarization-valley coupling in the system. Aside forming a basis for valleytronics, the multivalley dispersion is predicted to allow for spontaneous momentum symmetry breaking and two-mode squeezing under non-resonant and resonant excitation, respectively.

  6. Multivalley engineering in semiconductor microcavities

    PubMed Central

    Sun, M.; Savenko, I. G.; Flayac, H.; Liew, T. C. H.

    2017-01-01

    We consider exciton-photon coupling in semiconductor microcavities in which separate periodic potentials have been embedded for excitons and photons. We show theoretically that this system supports degenerate ground-states appearing at non-zero inplane momenta, corresponding to multiple valleys in reciprocal space, which are further separated in polarization corresponding to a polarization-valley coupling in the system. Aside forming a basis for valleytronics, the multivalley dispersion is predicted to allow for spontaneous momentum symmetry breaking and two-mode squeezing under non-resonant and resonant excitation, respectively. PMID:28367953

  7. Hafnia-plugged microcavities for thermal stability of selective emitters

    NASA Astrophysics Data System (ADS)

    Lee, Heon-Ju; Smyth, Katherine; Bathurst, Stephen; Chou, Jeffrey; Ghebrebrhan, Michael; Joannopoulos, John; Saka, Nannaji; Kim, Sang-Gook

    2013-06-01

    Two-dimensional arrays of micro-cavities effectively control photon motion and selectively emit radiation tailored to the preferred bandgap of photovoltaic (PV) cells, thus enhancing the efficiency of thermophotovoltaic energy conversion. At the high operating temperatures, however, the micro- and nano-patterned structures of the selective emitters quickly lose their integrity--obliterating the tight tolerances required for precise spectral control. Even if oxidation, recrystallization, and grain growth could be avoided with single-crystal tungsten (W) selective emitters with vacuum packaging, surface diffusion, evaporation, and re-condensation are not avoidable in long-term operation at high temperatures. The concept of a planar array of plugged micro-cavities to suppress the curvature-dependent thermal degradation modes is proposed and tested. Based on scale-accelerated failure tests of silicon devices, the lifetime of W selective emitters operating at 1100 K is estimated to be at least 30 yr.

  8. Stokes solitons in optical microcavities

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Solitons are wave packets that resist dispersion through a self-induced potential well. They are studied in many fields, but are especially well known in optics on account of the relative ease of their formation and control in optical fibre waveguides. Besides their many interesting properties, solitons are important to optical continuum generation, in mode-locked lasers, and have been considered as a natural way to convey data over great distances. Recently, solitons have been realized in microcavities, thereby bringing the power of microfabrication methods to future applications. This work reports a soliton not previously observed in optical systems, the Stokes soliton. The Stokes soliton forms and regenerates by optimizing its Raman interaction in space and time within an optical potential well shared with another soliton. The Stokes and the initial soliton belong to distinct transverse mode families and benefit from a form of soliton trapping that is new to microcavities and soliton lasers in general. The discovery of a new optical soliton can impact work in other areas of photonics, including nonlinear optics and spectroscopy.

  9. 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.

  10. Exciton-polariton wakefields in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Terças, H.; Mendonça, J. T.

    2016-02-01

    We consider the excitation of polariton wakefields due to a propagating light pulse in a semiconductor microcavity. We show that two kinds of wakes are possible, depending on the constituents fraction (either exciton or photon) of the polariton wavefunction. The nature of the wakefields (pure excitonic or polaritonic) can be controlled by changing the speed of propagation of the external pump. This process could be used as a diagnostic for the internal parameters of the microcavity.

  11. Near-field optical thin microcavity theory

    NASA Astrophysics Data System (ADS)

    Wu, Jiu Hui; Hou, Jiejie

    2016-01-01

    The thin microcavity theory for near-field optics is proposed in this study. By applying the power flow theorem and the variable theorem,the bi-harmonic differential governing equation for electromagnetic field of a three-dimensional thin microcavity is derived for the first time. Then by using the Hankel transform, this governing equation is solved exactly and all the electromagnetic components inside and outside the microcavity can be obtained accurately. According to the above theory, the near-field optical diffraction from a subwavelength aperture embedded in a thin conducting film is investigated, and numerical computations are performed to illustrate the edge effect by an enhancement factor of 1.8 and the depolarization phenomenon of the near-field transmission in terms of the distance from the film surface. This thin microcavity theory is verified by the good agreement between our results and those in the previous literatures. The thin microcavity theory presented in the study should be useful in the possible applications of the thin microcavities in near-field optics and thin-film optics.

  12. Semiconductor Microcavity Flow Spectroscopy of Intracellular Protein in Human Cells

    NASA Astrophysics Data System (ADS)

    Gourley, Paul; Cox, Jim; Hendricks, Judy; McDonald, Anthony; Copeland, Guild; Sasaki, Darryl; Skirboll, Steve; Curry, Mark

    2001-03-01

    The speed of light through a biofluid or biological cell is inversely related to the biomolecular concentration of proteins and other complex molecules that modify the refractive index at wavelengths accessible to semiconductor lasers. By placing a fluid or cell into a semiconductor microcavity laser, these decreases in light speed can be sensitively recorded in picoseconds as frequency red-shifts in the laser output spectrum. This biocavity laser equipped with microfluidics for transporting cells at high speed through the laser microcavity has shown potential for rapid analysis of biomolecular mass of normal and malignant human cells in their physiologic condition without time-consuming fixing, staining, or tagging. We have used biocavity laser spectroscopy to measure the optical properties of solutions of standard biomolecules (sugars, proteins, DNA, and ions) and human cells. The technique determines the frequency shift, relative to that of water, of spontaneous or stimulated emission from cavity filled with a biomolecular solution. The shift was also measured in human glioblastoma cells that had been sorted by conventional fluorescence-activated cell sorting according to protein content. The results show a direct correlation between protein measured by fluorescence and the frequency shift observed in the microcavity laser.

  13. 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

  14. 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

  15. 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.

  16. Telecom wavelength emitting single quantum dots coupled to InP-based photonic crystal microcavities

    NASA Astrophysics Data System (ADS)

    Kors, A.; Fuchs, K.; Yacob, M.; Reithmaier, J. P.; Benyoucef, M.

    2017-01-01

    Here we report on the fabrication and optical characterization of InP-based L3 photonic crystal (PhC) microcavities embedded with a medium density InAs/InP quantum dots (QDs) emitting at telecom wavelengths. The QDs are grown by solid source molecular beam epitaxy using a ripening technique. Micro-photoluminescence (μ-PL) measurements of PhC samples reveal sharp cavity modes with quality factors exceeding 8500. QDs emit highly linear-polarized light at telecom wavelengths with resolution-limited spectral linewidth below 50 μeV. Enhanced PL intensity of QDs in PhC is observed in comparison to the PL intensity of QDs in bulk semiconductors. The combination of excitation power-dependent and polarization-resolved μ-PL measurements reveal the existence of an exciton-biexciton system with a small fine-structure splitting.

  17. Schottky MSM junctions for carrier depletion in silicon photonic crystal microcavities.

    PubMed

    Haret, Laurent-Daniel; Checoury, Xavier; Bayle, Fabien; Cazier, Nicolas; Boucaud, Philippe; Combrié, Sylvain; de Rossi, Alfredo

    2013-04-22

    Collection of free carriers is a key issue in silicon photonics devices. We show that a lateral metal-semiconductor-metal Schottky junction is an efficient and simple way of dealing with that issue in a photonic crystal microcavity. Using a simple electrode design, and taking into account the optical mode profile, the resulting carrier distribution in the structure is calculated. We show that the corresponding effective free carrier lifetime can be reduced by 50 times when the bias is tuned. This allows one to maintain a high cavity quality factor under strong optical injection. In the fabricated structures, carrier depletion is correlated with transmission spectra and directly visualized by Electron Beam Induced Current pictures. These measurements demonstrate the validity of this carrier extraction principle. The design can still be optimized in order to obtain full carrier depletion at a smaller energy cost.

  18. GaAs micro-pyramids serving as optical micro-cavities

    SciTech Connect

    Karl, M.; Beck, T.; Li, S.; Hu, D. Z.; Schaadt, D. M.; Kalt, H.; Hetterich, M.

    2010-01-04

    An efficient light-matter coupling requires high-quality (Q) micro-cavities with small mode volume. We suggest GaAs micro-pyramids placed on top of AlAs/GaAs distributed Bragg reflectors to be promising candidates. The pyramids were fabricated by molecular-beam epitaxy, electron-beam lithography and a subsequent wet-chemical etching process using a sacrificial AlAs layer. Measured Q-factors of optical modes in single pyramids reach values up to 650. A finite-difference time-domain simulation assuming a simplified cone-shaped geometry suggests possible Q-factors up to 3600. To enhance the light confinement in the micro-pyramids we intend to overgrow the pyramidal facets with a Bragg mirror--results of preliminary tests are given.

  19. Application of ring down measurement approach to micro-cavities for bio-sensing applications

    NASA Astrophysics Data System (ADS)

    Cheema, M. I.; Kirk, Andrew G.

    2011-03-01

    Optical biosensors can detect biomarkers in the blood serum caused by either infections or exposure to toxins. Until now, most work on the micro-cavity biosensors has been based on measurement of the resonant frequency shift induced by binding of biomarkers to a cavity. However, frequency domain measurements are not precise for such high Q micro-cavities. We hypothesize that more accurate measurements and better noise tolerance can be achieved by the application of the ring down measurement approach to the micro-cavity in a biosensor. To test our hypothesis, we have developed a full vectorial finite element model of a silica toroidal micro-cavity immersed in water. Our modeling results show that a toroidal cavity with a major diameter of 70μm and a minor diameter of 6μm can achieve a sensitivity of 28.6μs/RIU refractive index units (RIU) at 580nm. Therefore, our sensor would achieve the resolution of 5 x 10-8 RIU by employing a detector with picosecond resolution. Hence we propose a micro-cavity ring down biosensor with high sensitivity which will find wide applications in real time and label free bio-sensing.

  20. 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.

  1. 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.

  2. 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.

  3. Rabi splitting enhancement in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Dickerson, James Henry, II

    The physics of the two-level atom has been the basis of research in atomic physics for much of the past several decades. One of the great successes of semiconductor physics has been its capability to mimic the phenomena of other physical systems. Many of the discoveries in atomic physics have prompted studies of the coupling between two-level atom-like structures and photonic system in semiconductor physics. Much of that work has investigated the optics of the energy exchange between atom-like systems and the electromagnetic field mode of the enclosing cavity. Since many applications of microcavities are governed by the control of the spontaneous emission from the structure, command of the emission relies on control of the coupling between the photonic and the excitonic modes of the system. When the energies of the interacting microcavity states are in resonance, the resulting degeneracy yields an energy split between the coincident modes. This energy split produces two branches of the resonant mixed states, which are called polaritons. The energy separation between the mixed state branches is called the vacuum Rabi splitting, Delta. The magnitude of the Rabi splitting is indicative of the coupling strength of the polariton modes. One of the major pursuits of this field has been to augment the control of the coupling strength between the cavity polariton modes. Comprehensive control over the polariton states, be it the modulation of the polariton energies or the suppression of one of the modes, is a key component in the development of microcavity devices. The goal of my thesis research was to discover a simple means to achieve control over the coupling between the photonic and excitonic modes of a microcavity. This entailed the parametric tuning of the Rabi splitting between the coupled modes of the microcavity. Furthermore, we hoped to attain the maximum possible Rabi splitting observed in GaAs/AlxGa1- xAs microcavities with quantum oscillators located only within

  4. Whispering gallery modes microcavities with J-aggregates and plasmonic hot spots

    NASA Astrophysics Data System (ADS)

    Rakovich, Yury P.; Melnikau, Dzmitry; Savateeva, Diana; Chuvilin, Andrey; Hillenbrand, Rainer

    2012-06-01

    We have studied the optical properties of a hybrid system consisting of cyanine dye J-aggregates (both PIC and TDBC) attached to a spherical microcavity. Instead of the commonly accepted chemical bonding of dye molecules to the surface of microspheres or deposition of dye-doped sol-gel film, in our experiments microspheres were coated with J-aggregate shell utilizing the layer-by-layer assembly of the ultrathin films. In this approach we aimed to take advantage of light confinement in the Whispering Gallery Modes (WGMs) microcavity by placing the emitter (shell of J-aggregates) just at the rim of the microsphere, where the resonant electromagnetic field reaches its maximum. A periodic structure of narrow peaks was observed in the photoluminescence spectrum of the J-aggregates, arising from the coupling between the emission of J-aggregates and the WGMs of the microcavity. The most striking result of our study is the observation of polarization sensitive mode damping caused by re-absorption of J-aggregate emission. This effect manifests itself in dominating emission from the transverse magnetic modes in the spectral region of J-aggregates absorption band where the transverse electric (TE) modes are strongly suppressed. Strong suppression of TE modes reflects preferential tangential orientation of transition dipole moment of J-aggregates in deposited microcavity shell. Observed polarization sensitive mode damping observed in the spectral region of high J-aggregate absorption can be used for suppression of unwanted modes in high Q optical resonators. We also demonstrate that the emission intensity can be further enhanced by depositing a hybrid layer of J-aggregates and Ag nanoparticles onto the spherical microcavity. Owing to the concerted action of WGMs and plasmonic hot spots in the Ag aggregates, we observe strongly enhanced Raman signal from the Jaggregates. Microcavities covered by J-aggregates and plasmonic nanoparticles could be thus useful for a variety of

  5. 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

  6. Exceptional points in anisotropic planar microcavities

    NASA Astrophysics Data System (ADS)

    Richter, Steffen; Michalsky, Tom; Sturm, Chris; Rosenow, Bernd; Grundmann, Marius; Schmidt-Grund, Rüdiger

    2017-02-01

    Planar microcavities allow the control and manipulation of spin polarization, manifested in phenomena like the optical spin Hall effect due to the intrinsic polarization mode splitting. Here, we study a transparent microcavity with broken rotational symmetry, realized by aligning the optic axis of a uniaxial cavity material in the cavity plane, giving rise to exceptional points in the dispersion relation. These occur pairwise, are circularly polarized, and are cores of polarization vortices. The exceptional points are result of the non-Hermitian character of the system and are in close relationship to singular optic axes in absorptive biaxial systems.

  7. 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.

  8. Nonlinear emission of semiconductor microcavities in the strong coupling regime

    PubMed

    Houdre; Weisbuch; Stanley; Oesterle; Ilegems

    2000-09-25

    We report on the nonlinear laserlike emission from semiconductor microcavities in the strong coupling regime. Under resonant continuous wave excitation we observe a highly emissive state. The energy, dispersion, and spatial extent of this state is measured and is found to be dispersionless and spatially localized. This state coexists with luminescence that follows the usual cavity-polariton dispersion. It is attributed to the amplification of luminescence by a parametric gain due to cavity-polariton scattering. Despite the resonant excitation at 1.6 K, we observe no sign of Bose-Einstein condensation nor Boser action.

  9. Field instability in high-quality dielectric sphere and disk: implication to the problem of laser-induced damage of microsphere and microdisk resonators

    NASA Astrophysics Data System (ADS)

    Gruzdev, Vitali E.; Libenson, Mikhail N.

    1999-04-01

    The problem of initiating of laser-induced damage (LID) of microspherical and microdisk resonators and nature of processes limiting ultimate pump intensity of the resonators are considered. Electrodynamic processes rather than absorption-induced heating are shown to play major role in initiating of LID of ideal passive resonators. Theoretical model to describe local increasing of high-power electromagnetic field in the microresonator is presented to study the processes. It is based on idea of formation of unstable field structure in resonant dielectric microcavity connected with formation of positive feedbacks resulting in light-induced variation of quality factor and its spectrum.

  10. 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

  11. Optical parametric oscillation in one-dimensional microcavities

    NASA Astrophysics Data System (ADS)

    Lecomte, Timothée; Ardizzone, Vincenzo; Abbarchi, Marco; Diederichs, Carole; Miard, Audrey; Lemaitre, Aristide; Sagnes, Isabelle; Senellart, Pascale; Bloch, Jacqueline; Delalande, Claude; Tignon, Jerome; Roussignol, Philippe

    2013-04-01

    We present a comprehensive investigation of optical parametric oscillation in resonantly excited one-dimensional semiconductor microcavities with embedded quantum wells. Such solid-state structures feature a fine control over light-matter coupling and produce a photonic/polaritonic mode fan that is exploited for the efficient emission of parametric beams. We implement an energy-degenerate optical parametric oscillator with balanced signal and idler intensities via a polarization-inverting mechanism. In this paper, we (i) precisely review the multimode photonic/polaritonic structure of individual emitters, (ii) provide a thorough comparison between experiment and theory, focusing on the power and the threshold dependence on the exciton-photon detuning, (iii) discuss the influence of inhomogeneous broadening of the excitonic transition and finite size, and (iv) find that a large exciton-photon detuning is a key parameter to reach a high output power and a high conversion efficiency. Our study highlights the predictive character of the polariton interaction theory and the flexibility of one-dimensional semiconductor microcavities as a platform to study parametric phenomena.

  12. 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.

  13. 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.

  14. 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.

  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. 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

  18. Optical microcavity scanning 3D tomography.

    PubMed

    Di Donato, Andrea; Criante, Luigino; LoTurco, Sara; Farina, Marco

    2014-10-01

    A scanning optical microcavity is exploited to achieve lens-free 3D tomography of microfluidic channels. The microcavity, powered by a low-coherence source, is realized by approaching a cleaved fiber to few tens of micrometers over the sample. The interference of scattered waves inside the cavity shapes the transverse field distribution by focusing the beam and overcoming the diffraction limit due to the optical-fiber numerical aperture. The focusing effect is also preserved in the inner layers of the sample, allowing optical 3D tomography. Analysis of microfluidic channels was demonstrated through this noninvasive technique. Although the experimental setup recalls the well-known fiber-optic Fourier-domain common-path optical coherence tomography, the proposed method has intrinsic characteristics that distinguish it from the former one.

  19. 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.

  20. Anomalous normal mode oscillations in semiconductor microcavities

    SciTech Connect

    Wang, H.; Hou, H.Q.; Hammons, B.E.

    1997-04-01

    Semiconductor microcavities as a composite exciton-cavity system can be characterized by two normal modes. Under an impulsive excitation by a short laser pulse, optical polarizations associated with the two normal modes have a {pi} phase difference. The total induced optical polarization is then expected to exhibit a sin{sup 2}({Omega}t)-like oscillation where 2{Omega} is the normal mode splitting, reflecting a coherent energy exchange between the exciton and cavity. In this paper the authors present experimental studies of normal mode oscillations using three-pulse transient four wave mixing (FWM). The result reveals surprisingly that when the cavity is tuned far below the exciton resonance, normal mode oscillation in the polarization is cos{sup 2}({Omega}t)-like, in contrast to what is expected form the simple normal mode model. This anomalous normal mode oscillation reflects the important role of virtual excitation of electronic states in semiconductor microcavities.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. A Perfect Electromagnetic Cavity: High Quality Factor in Subwavelength Dimensions

    NASA Astrophysics Data System (ADS)

    Ginis, Vincent; Tassin, Philippe; Soukoulis, Costas M.; Veretennicoff, Irina

    2010-03-01

    Transformation optics has recently provided a new way to look at the interaction between light and matter. It uses the analogy between the macroscopic Maxwell's equations in complex dielectrics and the free-space Maxwell's equations on the background of an arbitrary metric to exploit the full potential of metamaterials, of which the most exciting examples are invisibility cloaks. In this contribution, we want to show how transformation optics can be applied to design a cavity with extraordinary properties. We have demonstrated theoretically the existence of eigenmodes whose wavelength is much larger than the characteristic dimensions of the cavity. Furthermore, our design avoids the bending losses observed in traditional microcavities, so that the quality factor is only limited by intrinsic absorption of the materials. Such a ``perfect cavity'' may be interesting for applications involving optical data storage or quantum optics, where it can be used to control the rate of spontaneous emission through the Purcell effect.

  6. Dynamics of Semiconductor Microcavities Using Ultrashort Pulse Lasers

    NASA Astrophysics Data System (ADS)

    Rhee, June-Koo

    1995-01-01

    Using femtosecond optical spectroscopy, we perform an extensive study of dynamics of an AlAs/AlGaAs/GaAs-based semiconductor quantum microcavity, which exhibit cavity -polariton behavior owing to strong coupling between the exciton and cavity modes. We explore the dynamics of time -domain vacuum Rabi oscillations, the spatial coherence transfer of cavity-polariton states, and cavity-polariton dynamics in the nonlinear regime. In the time domain, when the microcavity is impulsively excited by a short coherent optical pulse, we observe the vacuum Rabi oscillations in the radiation, corresponding to the cavity-polariton mode splitting of the microcavity. Interferometric pump-probe measurements clearly show the coherent evolution of the cavity-polaritons. At high intensity, the normal mode splitting collapses due to bleaching of the excitonic oscillator strength. The dynamics of the splitting reveal the momentum relaxation of the cavity-polaritons due to inhomogeneous broadening, and provides evidence for delayed exciton-exciton scattering due to vacuum Rabi oscillation. When the cavity is excited coherently at an oblique angle, we also observe coherent radiation in the normal direction of the substrate, with a nearly fixed delay of 450 fs. This radiation is coherent with the excitation pulse and dependent on excitation density. Specifically, the initially-excited spatial cavity-polariton state is coherently transferred to the other spatial state selected by the cavity mode. The excitation dependence suggests this coherence transfer is associated with exciton scatterings. A density-matrix analysis for two cavity-polariton systems shows our model is in good qualitative agreement with the experiment. In order to perform femtosecond semiconductor spectroscopic experiments, it was necessary to develop the ultrafast laser source. We describe a cw-argon-laser -pumped Ti:sapphire laser system and a real-time femtosecond -optical-pulse analyzer, for femtosecond spectroscopy

  7. 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.

  8. Multistability of a coherent spin ensemble in a semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Paraïso, T. K.; Wouters, M.; Léger, Y.; Morier-Genoud, F.; Deveaud-Plédran, B.

    2010-08-01

    Coherent manipulation of spin ensembles is a key issue in the development of spintronics. In particular, multivalued spin switching may lead to new schemes of logic gating and memories. This phenomenon has been studied with atom vapours 30 years ago, but is still awaited in the solid state. Here, we demonstrate spin multistability with microcavity polaritons in a trap. Owing to the spinor nature of these light-matter quasiparticles and to the anisotropy of their interactions, we can optically control the spin state of a single confined level by tuning the excitation power, frequency and polarization. First, we realize high-efficiency power-dependent polarization switching. Then, at constant excitation power, we evidence polarization hysteresis and determine the conditions for realizing multivalued spin switching. Finally, we demonstrate an unexpected regime, where our system behaves as a high-contrast spin trigger. These results open new pathways to the development of advanced spintronics devices and to the realization of multivalued logic circuits.

  9. Electrically Pumped III-N Microcavity Light Emitters Incorporating an Oxide Confinement Aperture

    NASA Astrophysics Data System (ADS)

    Lai, Ying-Yu; Chang, Tsu-Chi; Li, Ya-Chen; Lu, Tien-Chang; Wang, Shing-Chung

    2017-01-01

    In this work, we report on electrically pumped III-N microcavity (MC) light emitters incorporating oxide confinement apertures. The utilized SiO2 aperture can provide a planar ITO design with a higher index contrast ( 1) over other previously reported approaches. The fabricated MC light emitter with a 15-μm-aperture shows a turn-on voltage of 3.3 V, which is comparable to conventional light emitting diodes (LEDs), showing a good electrical property of the proposed structure. A uniform light output profile within the emission aperture suggesting the good capability of current spreading and current confinement of ITO and SiO2 aperture, respectively. Although the quality factor ( Q) of fabricated MC is not high enough to achieve lasing action ( 500), a superlinear emission can still be reached under a high current injection density (2.83 kA/cm2) at 77 K through the exciton-exciton scattering, indicating the high potential of this structure for realizing excitonic vertical-cavity surface-emitting laser (VCSEL) action or even polariton laser after fabrication optimization.

  10. 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.

  11. Coherence expansion and polariton condensate formation in a semiconductor microcavity.

    PubMed

    Belykh, V V; Sibeldin, N N; Kulakovskii, V D; Glazov, M M; Semina, M A; Schneider, C; Höfling, S; Kamp, M; Forchel, A

    2013-03-29

    The dynamics of the expansion of the first order spatial coherence g(1) for a polariton system in a high-Q GaAs microcavity was investigated on the basis of Young's double slit experiment under 3 ps pulse excitation at the conditions of polariton Bose-Einstein condensation. It was found that in the process of condensate formation the coherence expands with a constant velocity of about 10(8)  cm/s. The measured coherence is smaller than that in a thermal equilibrium system during the growth of condensate density and well exceeds it at the end of condensate decay. The onset of spatial coherence is governed by polariton relaxation while condensate amplitude and phase fluctuations are not suppressed.

  12. 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

  13. Evaluation of cancer cell deformability by microcavity array.

    PubMed

    Yoshino, Tomoko; Tanaka, Tsuyoshi; Nakamura, Seita; Negishi, Ryo; Shionoiri, Nozomi; Hosokawa, Masahito; Matsunaga, Tadashi

    2017-03-01

    A cell entrapment device consisting of a microcavity array was used to analyze the deformability of MCF-10 human breast epithelial and MCF-7 human breast cancer cell lines by confocal laser scanning microscopy. Entrapment of up to 8 × 10(3) cells was achieved within 3 min. Protrusions were formed at the bottom surface of the array with a pore size of 3 μm. Protrusion length increased at higher filtration pressures and could be used to distinguish between MCF-7 and MCF-10 cells. These results indicate that our system is useful for high-throughput deformability analysis of cancer cells, which can provide insight into the mechanisms underlying tumor cell malignancy.

  14. 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.

  15. Multipartite polariton entanglement in semiconductor microcavities

    SciTech Connect

    Liew, T. C. H.; Savona, V.

    2011-09-15

    We study the entanglement of multiple polariton modes, which results in continuous variable cluster states suitable for quantum computation. Schemes are based on parametric scattering between spin-polarized lower and upper polariton branches in planar microcavities or spin-polarized orbital angular momentum states in mesa structures. Such systems are modeled by numerical solution of truncated density matrices and compared to the solution of the Heisenberg equations for the set of field correlators up to third order. Four-body entanglement is evidenced by violation of the van Loock-Furusawa quadripartite inequalities. We show that the entanglement is able to withstand a realistic strength of pure dephasing present in typical systems.

  16. Coupled spatial multimode solitons in microcavity wires

    NASA Astrophysics Data System (ADS)

    Slavcheva, G.; Gorbach, A. V.; Pimenov, A.

    2016-12-01

    A modal expansion approach is developed and employed to investigate and elucidate the nonlinear mechanism behind the multistability and formation of coupled multimode polariton solitons in microcavity wires. With pump switched on and realistic dissipation parameters, truncating the expansion up to the second-order wire mode, our model predicts two distinct coupled soliton branches: stable and unstable. Modulational stability of the stationary homogeneous solution and soliton branches stability are studied. Our simplified 1D model is in remarkably good agreement with the full 2D mean-field Gross-Pitaevskii model, reproducing correctly the soliton existence domain upon variation of pump amplitude and the onset of multistability.

  17. 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.

  18. 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.

  19. Electrically-detected magnetic resonance in semiconductor 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

    2013-12-04

    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.

  20. 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.

  1. Hydatid detection using the near-infrared transmission angular spectra of porous silicon microcavity biosensors.

    PubMed

    Li, Peng; Jia, Zhenhong; Lü, Guodong

    2017-03-20

    Hydatid, which is a parasitic disease, occurs today in many regions worldwide. Because it can present a serious threat to people's health, finding a fast, convenient, and economical means of detection is important. This paper proposes a label- and spectrophotometer-free apparatus that uses optical biological detection based on porous silicon microcavities. In this approach, the refractive index change induced by the biological reactions of a sample in a porous silicon microcavity is detected by measuring the change in the incidence angle corresponding to the maximum transmitted intensity of a near-infrared probe laser. This paper reports that the proposed method can achieve the label-free detection of 43 kDa molecular weight hydatid disease antigens with high sensitivity.

  2. Hydatid detection using the near-infrared transmission angular spectra of porous silicon microcavity biosensors

    PubMed Central

    Li, Peng; Jia, Zhenhong; Lü, Guodong

    2017-01-01

    Hydatid, which is a parasitic disease, occurs today in many regions worldwide. Because it can present a serious threat to people’s health, finding a fast, convenient, and economical means of detection is important. This paper proposes a label- and spectrophotometer-free apparatus that uses optical biological detection based on porous silicon microcavities. In this approach, the refractive index change induced by the biological reactions of a sample in a porous silicon microcavity is detected by measuring the change in the incidence angle corresponding to the maximum transmitted intensity of a near-infrared probe laser. This paper reports that the proposed method can achieve the label-free detection of 43 kDa molecular weight hydatid disease antigens with high sensitivity. PMID:28317861

  3. Hydatid detection using the near-infrared transmission angular spectra of porous silicon microcavity biosensors

    NASA Astrophysics Data System (ADS)

    Li, Peng; Jia, Zhenhong; Lü, Guodong

    2017-03-01

    Hydatid, which is a parasitic disease, occurs today in many regions worldwide. Because it can present a serious threat to people’s health, finding a fast, convenient, and economical means of detection is important. This paper proposes a label- and spectrophotometer-free apparatus that uses optical biological detection based on porous silicon microcavities. In this approach, the refractive index change induced by the biological reactions of a sample in a porous silicon microcavity is detected by measuring the change in the incidence angle corresponding to the maximum transmitted intensity of a near-infrared probe laser. This paper reports that the proposed method can achieve the label-free detection of 43 kDa molecular weight hydatid disease antigens with high sensitivity.

  4. Directional emission micro-cavity lasers with different device structures

    NASA Astrophysics Data System (ADS)

    Yan, Chang-ling; Shi, Jian-wei; Feng, Yuan; Hao, Yong-qin; Li, Hui; Zhang, Jian-jia; Li, Peng; Wang, Jia-bin

    2016-10-01

    The micro-cavity lasers support the ultra-low threshold and ultrahigh Q-factor, but several disadvantages impede further development, such as isotropic far-field profile pattern and low optical power output. To overcome the intrinsic problems, several deformed structures were proposed and investigated. In this paper we present directional emission micro-cavity lasers with limason-shaped, triangle-shaped, and ellipse shaped cavity structures. In experiment, mid-infrared InGaAs/InAlAs quantum cascade material was employed to fabricate these micro-cavity lasers, due to its advantages of lack of surface recombination, and inherently in-plane with transverse magnetic (TM) mode emission. The micro-cavity lasers with different device structures were operated and compared at room temperature, and a higher output power was also achieved by increasing the device structure size.

  5. Microcavity effects in the photoluminescence of hydrogenated amorphous silicon nitride

    NASA Astrophysics Data System (ADS)

    Serpenguzel, Ali; Aydinli, Atilla; Bek, Alpan

    1998-07-01

    Fabry-Perot microcavities are used for the alteration of photoluminescence in hydrogenated amorphous silicon nitride grown with and without ammonia. The photoluminescence is red-near-infrared for the samples grown without ammonia, and blue-green for the samples grown with ammonia. In the Fabry- Perot microcavities, the amplitude of the photoluminescence is enhanced, while its linewidth is reduced with respect to the bulk hydrogenated amorphous silicon nitride. The microcavity was realized by a metallic back mirror and a hydrogenated amorphous silicon nitride--air or a metallic front mirror. The transmittance, reflectance, and absorbance spectra were also measured and calculated. The calculated spectra agree well with the experimental spectra. The hydrogenated amorphous silicon nitride microcavity has potential for becoming a versatile silicon based optoelectronic device such as a color flat panel display, a resonant cavity enhanced light emitting diode, or a laser.

  6. Photonic Crystal Microcavities for Quantum Information Science

    NASA Astrophysics Data System (ADS)

    Hagemeier, Jenna Nicole

    Quantum information science and technology is a broad and fascinating field, encompassing diverse research areas such as materials science, atomic physics, superconductors, solid-state physics, and photonics. A goal of this field is to demonstrate the basic functions of information initialization, manipulation, and read-out in systems that take advantage of quantum physics to greatly enhance computing performance capabilities. In a hybrid quantum information network, different systems are used to perform different functions, to best exploit the advantageous properties of each system. For example, matter quantum bits (qubits) can be used for local data storage and manipulation while photonic qubits can be used for long-distance communication between storage points of the network. Our research focuses on the following two solid-state realizations of a matter qubit for the purpose of building such a hybrid quantum network: the electronic spin of a self-assembled indium arsenide quantum dot and the electronic spin of a nitrogen-vacancy defect center in diamond. Light--matter interactions are necessary to transfer the information from the matter qubit to the photonic qubit, and this interaction can be enhanced by embedding the spin system in an optical cavity. We focus on photonic crystal microcavities for this purpose, and we study interactions between the optical cavity modes and incorporated spin systems. To improve the performance of this spin--photon interface, it is important to maximize the coupling strength between the spin and photonic systems and to increase the read-out efficiency of information stored in the cavity. In this thesis, we present our work to deterministically couple a nitrogen-vacancy center in diamond to a photonic crystal microcavity in gallium phosphide. This is achieved by nanopositioning a pre-selected diamond nanocrystal in the intensity maximum of the optical cavity mode. We also present an optimized design of a photonic crystal

  7. 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)

  8. Microcavity-embedded, colour-tuneable, transparent organic solar cells.

    PubMed

    Chen, Yi-Hong; Chen, Chang-Wen; Huang, Zheng-Yu; Lin, Wei-Chieh; Lin, Li-Yen; Lin, Francis; Wong, Ken-Tsung; Lin, Hao-Wu

    2014-02-01

    In this work microcavity-capped colour-tuneable SMOSCs are evaluated. By adopting a microcavity-structured cathode with optical spacer layers of different thicknesses fabricated in a Ag/NPB/Ag structure, the transmission spectra of complete devices can be tuned over the entire visible-light region (400-750 nm). The fabricated semitransparent colour-tuneable solar cells show an average efficiency of 4.78% under 1-sun illumination.

  9. On-chip quantum optics with quantum dot microcavities.

    PubMed

    Stock, E; Albert, F; Hopfmann, C; Lermer, M; Schneider, C; Höfling, S; Forchel, A; Kamp, M; Reitzenstein, S

    2013-02-06

    A novel concept for on-chip quantum optics using an internal electrically pumped microlaser is presented. The microlaser resonantly excites a quantum dot microcavity system operating in the weak coupling regime of cavity quantum electrodynamics. This work presents the first on-chip application of quantum dot microlasers, and also opens up new avenues for the integration of individual microcavity structures into larger photonic networks.

  10. 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).

  11. Microcavity surface plasmon resonance bio-sensors

    NASA Astrophysics Data System (ADS)

    Mosavian, Nazanin

    This work discusses a miniature surface plasmon biosensor which uses a dielectric sub- micron diameter core with gold spherical shell. The shell has a subwavelength nanoaperture believed to excite stationary plasmon resonances at the biosensor's surface. The sub-micron cavity enhances the measurement sensitivity of molecules binding to the sensor surface. We used visible-range optical spectroscopy to study the wavelength shift as bio-molecules absorbed-desorbed at the shell surface. We also used Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) ablation to study the characteristics of microcavity surface plasmon resonance sensor (MSPRS) and the inner structure formed with metal deposition and its spectrum. We found that resonances at 580 nm and 670 nm responded to bound test agents and that Surface Plasmon Resonance (SPR) sensor intensity could be used to differentiate between D-glucose and L-glucose. The responsiveness of the system depended upon the mechanical integrity of the metallic surface coating.

  12. Recent results and latest views on microcavity LEDs

    NASA Astrophysics Data System (ADS)

    Weisbuch, Claude; David, Aurelien; Fujii, Tetsuo; Schwach, C.; DenBaars, Steven P.; Nakamura, Shuji; Rattier, M.; Benisty, Henri; Houdré, Romuald; Stanley, R.; Carlin, Jean-Francois; Krauss, Thomas F.; Smith, Christopher J. M.

    2004-06-01

    We are progressively approaching the physical limits of microcavity LEDs (MC-LEDs) for high brightness, high efficiency LEDs. They are promising high efficiency devices and they offer the very attractive prospect of full planar fabrication process. However, to compete with other high efficiency LED schemes, they need to approach or surpass the 50 % efficiency mark. We first explore the limits of planar MC-LEDs in both the GaAlInAsP and GaInAlN materials systems, and show that the single-step extraction limit is in the 40 % range at best, depending on the materials system used, with the largest part of the non-extracted light being emitted into guided modes. The waveguided light can itself be extracted by photon recycling, when the internal quantum efficiency is high. Otherwise, another extraction scheme for that light is provided by various photonic-crystal-assisted extraction schemes. Simple photonic crystals (PCs) appear to lack the omnidirectional extraction properties required. However, more rotation-invariant PCs like Archimedean tilings allow to obtain such extraction with added efficiencies already in the 10% range. We discuss the further improvements to such structures.

  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. Electroluminescence Studies on Longwavelength Indium Arsenide Quantum Dot Microcavities Grown on Gallium Arsenide

    DTIC Science & Technology

    2011-12-01

    ELECTROLUMINESCENCE STUDIES ON LONG WAVELENGTH INDIUM ARSENIDE QUANTUM DOT MICROCAVITIES GROWN ON GALLIUM ARSENIDE THESIS John C...11-46 ELECTROLUMINESCENCE STUDIES ON LONGWAVELENGTH INDIUM ARSENIDE QUANTUM DOT MICROCAVITIES GROWN ON GALLIUM ARSENIDE THESIS...58 1 ELECTROLUMINESCENCE STUDIES ON LONGWAVELENGTH INDIUM ARSENIDE QUANTUM DOT MICROCAVITIES GROWN ON GALLIUM ARSENIDE I

  15. Design and fabrication of microcavity-array superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    We have modeled, fabricated, and characterized superhydrophobic surfaces with a morphology formed of periodic microstructures which are cavities. This surface morphology is the inverse of that generally reported in the literature when the surface is formed of pillars or protrusions, and has the advantage that when immersed in water the confined air inside the cavities tends to expel the invading water. This differs from the case of a surface morphology formed of pillars or protrusions, for which water can penetrate irreversibly among the microstructures, necessitating complete drying of the surface in order to again recover its superhydrophobic character. We have developed a theoretical model that allows calculation of the microcavity dimensions needed to obtain superhydrophobic surfaces composed of patterns of such microcavities, and that provides estimates of the advancing and receding contact angle as a function of microcavity parameters. The model predicts that the cavity aspect ratio (depth-to-diameter ratio) can be much less than unity, indicating that the microcavities do not need to be deep in order to obtain a surface with enhanced superhydrophobic character. Specific microcavity patterns have been fabricated in polydimethylsiloxane and characterized by scanning electron microscopy, atomic force microscopy, and contact angle measurements. The measured advancing and receding contact angles are in good agreement with the predictions of the model.

  16. Organic Fabry-Perot micro-cavity for electro-optic sampling by amplitude modulation

    NASA Astrophysics Data System (ADS)

    Gaborit, G.; Martin, G.; Duvillaret, L.; Coutaz, J.-L.; Nguyen, C.; Hierle, R.; Zyss, J.

    2006-02-01

    We present herein a original concept of electro-optic (EO) probe for high frequency electric field measurements. This sensors is based on a thin organic layer of DR1-PMMA embedded in a high finesse Fabry-Perot cavity. The optimal orientation of DRl molecules, parallel to the face of the micro-cavity, has been obtained thanks to a lateral poling method. A r 33 of 2.5 pm/V has been reached for a 16 μm thick polymer layer. The final probe exhibits high sensitivity of 2V.cm -1.Hz -1/2.

  17. 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.

  18. Stroing single-photons in microcavities arrays

    NASA Astrophysics Data System (ADS)

    Mirza, Imran M.; Enk, S. J. Van; Kimble, H. J.

    2014-03-01

    Coupling light to arrays of microcavities is one of the most promising avenues to store/delay classical light pulses [F. Krauss, Nat. Phot. 2, 448-450 (2008)]. However, from the perspective of benefiting quantum communication protocols, the same ideas in principle can be extended down to the single-photon (quantum) level as well. Particularly, for the purposes of entanglement purification and quantum repeaters a reliable storage of single photons is needed. We consider in our work [I. M. Mirza, S. Van Enk, H. Kimble JOSA B, 30,10 (2013)] cavities that are coupled through an optical fiber which is assumed to be forming a Markovian bath. For this study two powerful open quantum system techniques, Input-Output theory for cascaded quantum systems and the Quantum Trajectory approach are used in combination. For the confirmation of photon delays the Time-Dependent Spectrum of such a single photon is obtained. Interestingly this leads to a hole-burning effect showing that only certain frequency components in the single photon wavepackets are stored inside the cavities and hence are delayed in time. Since on-demand production of single photons is not an easy task we include in our description the actual generation of the single photon by assuming a single emitter in one the resonators.

  19. 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].

  20. 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.

  1. Toluene optical fibre sensor based on air microcavity in PDMS

    NASA Astrophysics Data System (ADS)

    Kacik, Daniel; Martincek, Ivan

    2017-03-01

    We prepared and demonstrated a compact, simple-to-fabricate, air microcavity in polydimethylsiloxane (PDMS) placed at the end of a single-mode optical fibre. This microcavity creates a Fabry-Perot interferometer sensor able to measure concentrations of toluene vapour in air. Operation of the sensor is provided by diffusion of the toluene vapour to the PDMS, and the consequent extension of length d of the air microcavity in PDMS. The sensor response for the presence of vapours is fast and occurs within a few seconds. By using the prepared sensor toluene vapour concentration in air can be measured in the range from about 0.833 g.m-3 to saturation, with better sensitivity than 0.15 nm/g.m-3 up to maximal sensitivity 1.4 nm/g.m-3 at around concentration 100 g.m-3 in time 5 s.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Acoustic trapping in bubble-bounded micro-cavities

    NASA Astrophysics Data System (ADS)

    O'Mahoney, P.; McDougall, C.; Glynne-Jones, P.; MacDonald, M. P.

    2016-12-01

    We present a method for controllably producing longitudinal acoustic trapping sites inside microfluidic channels. Air bubbles are injected into a micro-capillary to create bubble-bounded `micro-cavities'. A cavity mode is formed that shows controlled longitudinal acoustic trapping between the two air/water interfaces along with the levitation to the centre of the channel that one would expect from a lower order lateral mode. 7 μm and 10 μm microspheres are trapped at the discrete acoustic trapping sites in these micro-cavities.We show this for several lengths of micro-cavity.

  7. Single-cell bacterium identification with a SOI optical microcavity

    NASA Astrophysics Data System (ADS)

    Tardif, M.; Jager, J.-B.; Marcoux, P. R.; Uchiyamada, K.; Picard, E.; Hadji, E.; Peyrade, D.

    2016-09-01

    Photonic crystals and microcavities act as on-chip nano-optical tweezers for identification and manipulation of biological objects. Until now, optical trapping of virus and bacteria has been achieved and their presence in the vicinity of the optical resonator is deduced by the shift in the resonant wavelength. Here, we show trapping and identification of bacteria through a properly tuned silicon on insulator microcavity. Through the spatial and temporal observations of bacteria-cavity interaction, the optical identification of three different kinds of bacteria is demonstrated.

  8. A compact dual-band bandpass filter based on porous silicon dual-microcavity of one-dimensional photonic crystal

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Zhang, Hong-yan

    2015-03-01

    We propose a compact dual-band bandpass filter (BPF) based on one-dimensional porous silicon (PS) photonic crystal by electrochemical etching. By inserting three periods of high and low reflective index layers in the center of porous silicon microcavity (PSM), two sharp resonant peaks appear in the high reflectivity stop band on both sides of the resonance wavelength. Through simulation and experiment, the physical mechanisms of the two resonance peaks and the resonance wavelength are also studied. It is found that the resonance wavelength can be tuned only by adjusting the effective optical thickness (EOT) of each PS layer, in which different resonance wavelengths have different widths between the two sharp resonance peaks. Besides, the analysis indicates that oxidization makes the blue shift become larger for high wavelength than that for low wavelength. Such a fabricated BPF based on PS dual-microcavity is easy to be fabricated and low cost, which benefits the application of integrated optical devices.

  9. A proposal for the generation of optical frequency comb in temperature insensitive microcavity

    NASA Astrophysics Data System (ADS)

    Lei, Xun; Bian, Dandan; Chen, Shaowu

    2016-11-01

    We numerically simulate the generation of an optical frequency comb (OFC) in a microring based on the traditional Si3N4 strip waveguide and a temperature compensated slot waveguide. The results show that OFCs are susceptible to temperature with strip waveguide while they can keep stable when temperature changes 10 K in either low-Q (105) or high-Q (106) microcavity with the well-designed slot waveguide, which has great superiority in practical applications where the temperature drift of the cavity due to the intense pump or surrounding change is unavoidable. Project supported by the National Natural Science Foundation of China (Grant Nos. 61435002, 61527823, and 61321063).

  10. 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).

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

    SciTech Connect

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

    2014-12-08

    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)

  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. Progress Toward Single-Photon-Level Nonlinear Optics in Crystalline Microcavities

    NASA Astrophysics Data System (ADS)

    Kowligy, Abijith S.

    Over the last two decades, the emergence of quantum information science has uncovered many practical applications in areas such as communications, imaging, and sensing where harnessing quantum features of Nature provides tremendous benefits over existing methods exploiting classical physical phenomena. In this effort, one of the frontiers of research has been to identify and utilize quantum phenomena that are not susceptible to environmental and parasitic noise processes. Quantum photonics has been at the forefront of these studies because it allows room-temperature access to its inherently quantum-mechanical features, and allows leveraging the mature telecommunication industry. Accompanying the weak environmental influence, however, are also weak optical nonlinearities. Efficient nonlinear optical interactions are indispensible for many of the existing protocols for quantum optical computation and communication, e.g. high-fidelity entangling quantum logic gates rely on large nonlinear responses at the one- or few-photon-level. While this has been addressed to a great extent by interfacing photons with single quantum emitters and cold atomic gases, scalability has remained elusive. In this work, we identify the macroscopic second-order nonlinear polarization as a robust platform to address this challenge, and utilize the recent advances in the burgeoning field of optical microcavities to enhance this nonlinear response. In particular, we show theoretically that by using the quantum Zeno effect, low-noise, single-photon-level optical nonlinearities can be realized in lithium niobate whispering-gallery-mode microcavities, and present experimental progress toward this goal. Using the measured strength of the second-order nonlinear response in lithium niobate, we modeled the nonlinear system in the strong coupling regime using the Schrodinger picture framework and theoretically demonstrated that the single-photon-level operation can be observed for cavity lifetimes in

  14. Bacterial sensing using phage-functionalized whispering gallery microcavities

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    Whispering gallery optical microcavities are structures which can efficiently confine light at the micro scale. This confinement is based on total internal reflection of light at the interface between the cavity and the surrounding medium. Devices based on optical microcavities have a wide range of applications, such as microlasers, quantum optical devices and much more. In this work, we describe a biosensing application of these optical microcavities for the label-free detection of bacteria. In order for the sensor to be specific to a particular species of bacteria, we need to properly functionalize its surface so that only that kind of bacteria will produce a signal. The microcavity surface is first functionalized using PEGylated aminosilane. We then introduce phage-derived proteins that are specific to the bacteria we want to detect. The binding between the bacteria and the phage proteins creates a perturbation to the cavity field that leads to a thermo-optic effect. This effect is then observed as a shift in the resonance features of the transmission spectrum. We performed experimental measurements using a tapered fiber to couple the light from red laser (635 nm) into the resonator.

  15. 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.

  16. Nonlinear optics of multi-mode planar photonic crystal microcavities

    NASA Astrophysics Data System (ADS)

    McCutcheon, Murray William

    The nonlinear properties of multi-mode InP and Si planar photonic crystal microcavities are investigated in experiments relevant to integrated schemes for classical and quantum optical information processing. Normally incident, short laser pulses are used to coherently initialize the relative phase and amplitudes of two modes of a single-missing-hole InP microcavity. The two modes are orthogonally polarized, and separated by less than the bandwidth of the ˜ 130 fs excitation pulses. The relative amplitudes of the two modes can be controlled by adjusting the polarization and the centre frequency of the excitation beam. Cross-polarized detection of the resonantly scattered light reveals a well-defined relative phase between the modes that is characteristic of their coherence. When the short-pulse excitation is used to coherently excite two modes in a three-hole line-defect (L3) InP microcavity, second-order harmonic radiation is observed due to the interactions of the resonant fields with the second-order nonlinear susceptibility (chi(2)) of the host InP slab. Second-harmonic and sum-frequency generated signals are observed due to the intra- and inter-mode nonlinear mixing of the microcavity fields. When a separate non-resonant pulse is focussed onto an InP microcavity, sum-frequency light is generated conditional to the resonant mode population of the microcavity. The conditionally generated signals can be tuned by tuning the frequency of the non-resonant pulse. All of the results can be explained with reference to the bulk chi(2) properties of the InP slab. While the transient, multi-mode response of the microcavities is harnessed with the short-pulse technique, a continuous wave excitation laser exploits the local-field enhancement intrinsic to these wavelength-scale microcavities. A single-mode InP L3-microcavity with Q = 3,800 is pumped on resonance with a CW laser, and the 2D pattern of far-field second-harmonic radiation is directly imaged. The second

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  19. 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.

  20. 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.

  1. Decreased sleep quality in high myopia children

    PubMed Central

    Ayaki, Masahiko; Torii, Hidemasa; Tsubota, Kazuo; Negishi, Kazuno

    2016-01-01

    The aim of the present study was to evaluate sleep quality in myopic children and adults. This cross sectional study surveyed 486 participants aged from 10 to 59 years with refractive errors using a questionnaire containing the Pittsburgh Sleep Quality Index (PSQI) and Hospital Anxiety and Depression Scale (HADS). Children (< 20 years) in the high myopia group exhibited the poorest PSQI scores (P < 0.01), while the adults showed no such correlations. Subscales of PSQI and HADS in children disclosed that the high myopia groups had the shortest sleep duration (P < 0.01), worst subjective sleep scores (P < 0.001), and latest bedtime (P < 0.05). Regression analyses in children significantly correlated myopic errors with PSQI (P < 0.05), sleep duration (P < 0.01), and bedtime (P < 0.01). Sleep efficacy (P < 0.05) and daytime dysfunction (P < 0.05) were significantly better in contact-lens users compared to the respective non-user groups across all participants. In conclusion, sleep quality in children was significantly correlated with myopic error, with the high myopia group worst affected. PMID:27650408

  2. Intimate effects of surface functionalization of porous silicon microcavities on biosensing performance

    NASA Astrophysics Data System (ADS)

    Martin, M.; Massif, L.; Estephan, E.; Saab, M.-b.; Cloitre, T.; Larroque, C.; Agarwal, V.; Cuisinier, F. J. G.; Le Lay, G.; Gergely, C.

    2011-10-01

    We study the effect of different surface functionalization methods on the sensing performances of porous silicon (PSi) microcavities when used for detection of biomolecules. Previous research on porous silicon demonstrated versatility of these devices for sensor applications based on their photonic responses. The interface between biological molecules and the Si semiconductor surface is a key issue for improving biomolecular recognition in these devices. PSi microcavities were fabricated to reveal reflectivity pass-band spectra in the visible and near-infrared domain. To assure uniform infiltration of proteins the number of layers of Bragg mirrors was limited to five, the first layer being of high porosity. In one approach the devices were thermally oxidized and functionalized to assure covalent binding of molecules. Secondly, the as etched PSi surface was modified with adhesion peptides isolated via phage display technology and presenting high binding capacity for Si. Functionalization and molecular binding events were monitored via reflectometric interference spectra as shifts in the resonance peaks of the cavity structure due to changes in the refractive index when a biomolecule is attached to the large internal surface of PSi. Improved sensitivity is obtained due to the peptide interface linkers between the PSi and biological molecules compared to the silanized devices. We investigate the formation of peptide-Si interface layer via X-ray photoelectron spectroscopy, scanning tunneling microscopy and scanning electron microscopy.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  4. Multiplexed specific label-free detection of NCI-H358 lung cancer cell line lysates with silicon based photonic crystal microcavity biosensors.

    PubMed

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Drabkin, Harry A; Gemmill, Robert M; Simon, George R; Chin, Steve H; Chen, Ray T

    2013-05-15

    We experimentally demonstrate label-free photonic crystal (PC) microcavity biosensors in silicon-on-insulator (SOI) to detect the epithelial-mesenchymal transition (EMT) transcription factor, ZEB1, in minute volumes of sample. Multiplexed specific detection of ZEB1 in lysates from NCI-H358 lung cancer cells down to an estimated concentration of 2 cells per micro-liter is demonstrated. L13 photonic crystal microcavities, coupled to W1 photonic crystal waveguides, are employed in which resonances show high Q in the bio-ambient phosphate buffered saline (PBS). When the sensor surface is derivatized with a specific antibody, the binding of the corresponding antigen from a complex whole-cell lysate generates a change in refractive index in the vicinity of the photonic crystal microcavity, leading to a change in the resonance wavelength of the resonance modes of the photonic crystal microcavity. The shift in the resonance wavelength reveals the presence of the antigen. The sensor cavity has a surface area of ∼11μm(2). Multiplexed sensors permit simultaneous detection of many binding interactions with specific immobilized antibodies from the same bio-sample at the same instant of time. Specificity was demonstrated using a sandwich assay which further amplifies the detection sensitivity at low concentrations. The device represents a proof-of-concept demonstration of label-free, high throughput, multiplexed detection of cancer cells with specificity and sensitivity on a silicon chip platform.

  5. 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.

  6. Full color organic light-emitting devices with microcavity structure and color filter.

    PubMed

    Zhang, Weiwei; Liu, Hongyu; Sun, Runguang

    2009-05-11

    This letter demonstrated the fabrication of the full color passive matrix organic light-emitting devices based on the combination of the microcavity structure, color filter and a common white polymeric OLED. In the microcavity structure, patterned ITO terraces with different thickness were used as the anode as well as cavity spacer. The primary color emitting peaks were originally generated by the microcavity and then the second resonance peak was absorbed by the color filter.

  7. 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).

  8. Microstructured optical fiber-based micro-cavity sensor for chemical detection

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Ahn, Jin-Chul; Chung, Phil-Sang; Chung, Youngjoo

    2014-02-01

    The studies on microstructured optical fibers (MOF) have drawn considerable interest and played an important role in many applications. MOFs provide unique optical properties and controllable modal properties because of their flexibilities on manipulation of the transmission spectrum and the waveguide dispersion properties. MOFs are especially useful for optical sensing applications because the micro-structured air channels in MOF can host various types of analytes such as liquids, gases, and chemical molecules. Recently, many studies have focused on the development of MOF-based optical sensors for various gases and chemical molecules. We propose a compact, and highly sensitive optical micro-cavity chemical sensor using microstructured fiber. The sensor probe is composed of a hollow optical fiber and end cleaved microstructured fiber with a solid core. The interference spectrum resulting from the reflected light at the silica and air interfaces changes when the micro-cavity is infiltrated with external chemical molecules. This structure enables the direct detection of chemical molecules such as volatile organic compounds (VOCs) without the introduction of any permeable material.

  9. Light-matter interaction in a microcavity-controlled graphene transistor.

    PubMed

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

    2012-06-19

    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.

  10. 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

  11. Applications of Optical Microcavity Resonators in Analytical Chemistry.

    PubMed

    Wade, James H; Bailey, Ryan C

    2016-06-12

    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.

  12. 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

  13. 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.

  14. [Quality management is associated with high quality services in health care].

    PubMed

    Nielsen, Tenna Hassert; Riis, Allan; Mainz, Jan; Jensen, Anne-Louise Degn

    2013-12-09

    In these years, quality management has been the focus in order to meet high quality services for the patients in Danish health care. This article provides information on quality management and quality improvement and it evaluates its effectiveness in achieving better organizational structures, processes and results in Danish health-care organizations. Our findings generally support that quality management is associated with high quality services in health care.

  15. 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.

  16. Effect of physisorption and chemisorption of water on resonant modes of rolled-up tubular microcavities

    PubMed Central

    2013-01-01

    Both blue- and redshifts of resonant modes are observed in the rolled-up Y2O3/ZrO2 tubular microcavity during a conformal oxide coating process. Our investigation based on spectral analyses suggests that there are two competitive processes during coating: desorption of both chemically and physically absorbed water molecules and increase of the tube wall thickness. The redshift is due to the increase of the wall thickness and corresponding light confinement enhancement. On the other hand, desorption of water molecules by heating leads to a blueshift. The balance of these two factors produces the observed bi-directional shift of the modes while they both contribute to promoted quality factor after coating. PMID:24344644

  17. Ultra-sensitive chemical vapor detection using micro-cavity photothermal spectroscopy.

    PubMed

    Hu, Juejun

    2010-10-11

    In this paper, I systematically investigated Micro-Cavity PhotoThermal Spectroscopy (MC-PTS), a novel technique for ultra-sensitive detection of chemical molecular species. I first derive the photothermal enhancement factor and noise characteristics of the technique using a generic theoretical model, followed by numerical analysis of a design example using chalcogenide glass micro-disk cavities. Guidelines for sensor material selection and device design are formulated based on the theoretical insight. The numerical analysis shows that this technique features a record photothermal enhancement factor of 10(4) with respect to conventional cavity-enhanced (multi-pass) infrared absorption spectroscopy, and is capable of detecting non-preconcentrated chemical vapor molecules down to the ppt level with a moderate cavity quality factor of 10(5) and a pump laser power of 0.1 W. Such performance qualifies this technique as one of the most sensitive methods for chemical vapor spectroscopic analysis.

  18. Behavior of three modes of decay channels and their self-energies of elliptic dielectric microcavity

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The Lamb shift (self-energy) of an elliptic dielectric microcavity is studied. We show that the size of the Lamb shift, which is a small energy shift due to the system-environment coupling in the quantum regime, is dependent on the geometry of the boundary conditions. It shows a global transition depending on the eccentricity of the ellipsis. These transitions can be classified into three types of decay channels known as whispering-gallery modes, stable-bouncing-ball modes, and unstable-bouncing-ball modes. These modes are manifested through the Poincaré surface of section with the Husimi distribution function in classical phase space. It is found that the similarity (measured in Bhattacharyya distance) between the Husimi distributions below critical lines of two different modes increases as the difference of their self-energies decreases when the quality factors of the modes are on the same order of magnitude.

  19. 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.

  20. The Coupling of Zero-Dimensional Exciton and Photon States: A Quantum Dot in a Spherical Microcavity

    DTIC Science & Technology

    2001-06-01

    the electric 179 180 Microcavity and Photonic Cristal (a) (b) _..•rQ Fig. 1. (a) A schematic diagram of a spherical microcavity with a quantum dot at...core is 2.7 while the refractive indices 182 Microcavity and Photonic Cristal of the layers forming the Bragg reflector are 1.45 and 2.7 and correspond

  1. Method for synthesis of high quality graphene

    DOEpatents

    Lanzara, Alessandra [Piedmont, CA; Schmid, Andreas K [Berkeley, CA; Yu, Xiaozhu [Berkeley, CA; Hwang, Choonkyu [Albany, CA; Kohl, Annemarie [Beneditkbeuern, DE; Jozwiak, Chris M [Oakland, CA

    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.

  2. 1.5 MU M Fabry-Perot Microcavities Based on Hydrogenated Silicon and Related Materials

    DTIC Science & Technology

    2001-06-01

    limited by sensitivity of InGaAs photodiode. A sharp 1.54 jtm peak corresponds to a resonant mode of the MC. 167 168 Microcavity and Photonic Cristal A C B...transmission spectra are found to be close to each other in agreement with our theoretical analysis. 170 Microcavity and Photonic Cristal 2. Conclusions In

  3. 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.

  4. Particle trapping and impedance measurement using bilayer electrodes integrated with microcavity structure

    NASA Astrophysics Data System (ADS)

    Chen, Guan-Ting; Liu, Chia-Feng; Jang, Ling-Sheng; Li, Shun-Lai; Wang, Min-Haw

    2017-03-01

    Traditional planar electrodes for single-particle impedance measurement have difficulty in trapping and positioning particles. This paper proposes a microfluidic device for single-particle trapping and impedance measurement with a microcavity configuration. A carbon dioxide (CO2) laser technique was used to fabricate the microcavity structure, which can capture 15 µm diameter particles without requiring additional trapping structures. The measurement electrodes on both sides of the microcavity were fabricated using electroplating and deposition techniques. The advantages of the microcavity structure and electrodes are discussed. The bottom electrode spreads into the microcavity to increase measurement sensitivity and shrink the exit aperture to around 10 µm for particle trapping. The experimental results show that the device successfully captured particles and distinguished the impedance of a particle from that of phosphate-buffered saline solution.

  5. A fiber inclinometer using a fiber microtaper with an air-gap microcavity fiber interferometer

    NASA Astrophysics Data System (ADS)

    Feng, Zhongyao; Gang, Tingting; Hu, Manli; Qiao, Xueguang; Liu, Nan; Rong, Qiangzhou

    2016-04-01

    A micro-inclinometer is proposed and demonstrated experimentally; the device consists of a micro-fiber taper followed by an air-gap microcavity. A part of the core mode can couple to cladding modes via the taper. These cladding modes and residual core modes transmitted to downstream of the Fabry-Perot (FP) interferometer. A fraction of these modes are reflected back to the SMF by two surfaces of the FP cavity and eventually recoupled to the leading-in SMF, resulting in a well-defined interference spectrum. The fringe contrast of the interferometer is highly sensitive to fiber bending with direction-independence and thus is capable of measuring tilt angles in high resolution. In addition, the interference wavelength always remains unchanged during the fiber bending.

  6. 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)

  7. 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

  8. 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.

  9. Strong photoluminescence of the porous silicon with HfO2-filled microcavities

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Greatly enhanced blue emission was observed at room temperature in the single-crystal silicon with HfO2 filled into its microcavities. The broad blue band light was emitted from both the HfO2 dielectric and the porous Si. The ferroelectricity of HfO2 enhances the blue emission from Si by its filling into the microcaivities. At the same time, HfO2 contributes to the light emission for the transitions of the defect levels for oxygen vacancy. The observation of greatly enhanced blue light emission of the porous Si filled with HfO2 dielectric is remarkable as both HfO2 and Si are highly compatible with Si-based electronic industry.

  10. Phase-space views into dye-microcavity thermalized and condensed photons

    NASA Astrophysics Data System (ADS)

    Marelic, Jakov; Walker, Benjamin T.; Nyman, Robert A.

    2016-12-01

    We have observed momentum- and position-resolved spectra and images of the photoluminescence from thermalized and condensed dye-microcavity photons. The spectra yield the dispersion relation and the potential energy landscape for the photons. From this dispersion relation, below condensation threshold, we find that the effective mass is that of a bare cavity photon, not a polariton. Above threshold, we place an upper bound on the dimensionless two-dimensional interaction strength of g ˜≲10-3 , which is compatible with existing estimates. Both photon-photon and photon-molecule interactions are weak. The temperature is found to be independent of momentum, but dependent on pump spot size, indicating that the system is ergodic but not perfectly at thermal equilibrium. Condensation always happens first in the mode with lowest potential and lowest kinetic energy, although at very high pump powers multimode condensation occurs into other modes.

  11. Enhancement of second harmonic generation in nanocrystalline SiC films based natural microcavities

    NASA Astrophysics Data System (ADS)

    Semenov, A. V.; Skorik, S. N.; Jedryka, J.; Ozga, K.; Kityk, I. V.

    2017-01-01

    We explore second harmonic generation (SHG) features of nanocrystalline SiC films based natural microcavities (MC) with resonance modes in the vicinity of the fundamental radiation at 1064 nm wavelength for nanocrystalline films of 24R, 27R polytypes characterized by high radiation doubling frequency coefficients. The natural walls of the SiC NC serve a role of cavities. To learn the nonlinear resonance features of the MC near the fundamental wavelength 1064 nm three series of the nc-SiC films indicated as 7495, 7517 and 7522 with thicknesses varying within 250-600 nm were fabricated. The role of the coherent and non-coherent contributions with taking into an account of cavity resonance modes is discussed. The giant increase of the SHG was achieved which may be used for further fabrication of the frequency transducers and nonlinear optical triggers.

  12. Monolithic single GaN nanowire laser with photonic crystal microcavity on silicon

    NASA Astrophysics Data System (ADS)

    Heo, Junseok; Guo, Wei; Bhattacharya, Pallab

    2011-01-01

    Optically pumped lasing at room temperature in a silicon based monolithic single GaN nanowire with a two-dimensional photonic crystal microcavity is demonstrated. Catalyst-free nanowires with low density (˜108 cm-2) are grown on Si by plasma-assisted molecular beam epitaxy. High resolution transmission electron microscopy images reveal that the nanowires are of wurtzite structure and they have no observable defects. A single nanowire laser fabricated on Si is characterized by a lasing transition at λ =371.3 nm with a linewidth of 0.55 nm. The threshold is observed at a pump power density of ˜120 kW/cm2 and the spontaneous emission factor β is estimated to be 0.08.

  13. 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.

  14. Quantum well in a microcavity with injected squeezed vacuum

    SciTech Connect

    Erenso, Daniel; Vyas, Reeta; Singh, Surendra

    2003-01-01

    A quantum well with a single exciton mode in a microcavity driven by squeezed vacuum is studied in the low exciton density regime. By solving the quantum Langevin equations, we study the intensity, spectrum, and intensity correlation function for the fluorescent light. An expression for the Q function of the field inside the cavity is derived from the solutions of the quantum Langevin equations. Using the Q function, the intracavity photon number distribution and the quadrature fluctuations for both the cavity and fluorescent fields are studied. Several interesting and new effects due to squeezed vacuum are found.

  15. Faraday rotation in bilayer graphene-based integrated microcavity.

    PubMed

    Da, Hai-Xia; Yan, Xiao-Hong

    2016-01-01

    Bernal-stacked bilayer graphene has rich ground states with various broken symmetries, allowing the existence of magneto-optical (MO) effects even in the absence of an external magnetic field. Here we report controllable Faraday rotation (FR) of bilayer graphene induced by electrostatic gate voltage, whose value is 10 times smaller than the case of single layer graphene with a magnetic field. A proposed bilayer graphene-based microcavity configuration enables the enhanced FR angle due to the large localized electromagnetic field. Our results offer unique opportunities to apply bilayer graphene for MO devices.

  16. 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

    2016-01-08

    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.

  17. Spoked-ring microcavities: enabling seamless integration of nanophotonics in unmodified advanced CMOS microelectronics chips

    NASA Astrophysics Data System (ADS)

    Wade, Mark T.; Shainline, Jeffrey M.; Orcutt, Jason S.; Ram, Rajeev J.; Stojanovic, Vladimir; Popovic, Milos A.

    2014-03-01

    We present the spoked-ring microcavity, a nanophotonic building block enabling energy-efficient, active photonics in unmodified, advanced CMOS microelectronics processes. The cavity is realized in the IBM 45nm SOI CMOS process - the same process used to make many commercially available microprocessors including the IBM Power7 and Sony Playstation 3 processors. In advanced SOI CMOS processes, no partial etch steps and no vertical junctions are available, which limits the types of optical cavities that can be used for active nanophotonics. To enable efficient active devices with no process modifications, we designed a novel spoked-ring microcavity which is fully compatible with the constraints of the process. As a modulator, the device leverages the sub-100nm lithography resolution of the process to create radially extending p-n junctions, providing high optical fill factor depletion-mode modulation and thereby eliminating the need for a vertical junction. The device is made entirely in the transistor active layer, low-loss crystalline silicon, which eliminates the need for a partial etch commonly used to create ridge cavities. In this work, we present the full optical and electrical design of the cavity including rigorous mode solver and FDTD simulations to design the Qlimiting electrical contacts and the coupling/excitation. We address the layout of active photonics within the mask set of a standard advanced CMOS process and show that high-performance photonic devices can be seamlessly monolithically integrated alongside electronics on the same chip. The present designs enable monolithically integrated optoelectronic transceivers on a single advanced CMOS chip, without requiring any process changes, enabling the penetration of photonics into the microprocessor.

  18. Developing high quality low cost healthcare goods.

    PubMed

    Fox, Stephen

    2002-06-01

    The quality and cost of healthcare is a major concern in both Britain and America. Yet, despite much debate and many initiatives, the provision of healthcare is often unreliable and expensive (Goldsmith, 2001). In this article by Dr Stephen Fox, it is proposed that wider application of design methodologies during the development of healthcare goods could make a significant contribution to increasing quality and reducing costs.

  19. 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.

  20. 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

  1. 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.

  2. Multiplexed refractive index-based sensing using optical fiber microcavities

    NASA Astrophysics Data System (ADS)

    Warren-Smith, Stephen C.; André, Ricardo M.; Dellith, Jan; Bartelt, Hartmut

    2016-04-01

    Optical fibers are promising tools for performing biological and biomedical sensing due to their small cross section and potential for multiplexing. In particular, fabricating ultra-small sensing devices is of increasing interest for measuring biological material such as cells. A promising direction is the use of interferometric techniques combined with optical fiber post-processing. In this work we present recent progress in the development of Fabry-Perot micro-cavities written into optical fiber tapers using focused ion beam (FIB) milling. We first demonstrate that FIB milled optical fiber microcavities are sensitive enough to measure polyelectrolyte layer deposition. We then present new results on the fabrication and optical characterization of serially-multiplexed dual cavity micro-sensors. Two cavities were written serially along the fiber with two different cavity lengths, producing a total of four reflecting surfaces and thus six possible interferometric pairs/cavities. By using fast Fourier transform it is possible to obtain de-multiplexed measurements for each cavity. This will be particularly important for bioassays where positive and negative controls are required to be measured within close spatial proximity.

  3. Raman discrimination of bacterial strains using multilayered microcavity substrates

    NASA Astrophysics Data System (ADS)

    Sharma, Shiv K.; Dykes, Ava C.; Misra, Anupam K.; Kamemoto, Lori E.; Bates, David E.

    2011-05-01

    Surface-enhanced Raman scattering (SERS) utilizing colloidal silver and gold has been demonstrated to provide a rapid means of measuring the Raman spectra of microorganisms in the fingerprint region. In this study, we have introduced microcavity substrates coated with alternating layers of silver and gold thin films for measuring the Raman spectra of four strains of E. coli. These microcavitiy substrates have been prepared by placing glass microspheres between two polished aluminum substrates and pressing them together using a standard lab press. After removing the glass microspheres from the substrates, the substrates have been coated with 15 to 70 nm thick films of chromium, silver and gold in a precise order. The cavities were evaluated for SERS enhancement by measuring Raman spectra of dilute rhodamine 6G (R6G) down to 10-8 M. With these microcavities, we have investigated the SERS spectra of four chemically competent strains of E. coli (One Shot OmniMAX 2-T1, Mach1-T1, Stbl3, and TOP10). Replicate SERS spectra of all the four e-coli strains show excellent reproducibility. Visual examination of the spectra, however, reveals differences in the spectra of these strains. To confirm this observation, we have used multivariate analysis for positive identification and discrimination between the strains.

  4. Directional emission from dye-functionalized plasmonic DNA superlattice microcavities.

    PubMed

    Park, Daniel J; Ku, Jessie C; Sun, Lin; Lethiec, Clotilde M; Stern, Nathaniel P; Schatz, George C; Mirkin, Chad A

    2017-01-17

    Three-dimensional plasmonic superlattice microcavities, made from programmable atom equivalents comprising gold nanoparticles functionalized with DNA, are used as a testbed to study directional light emission. DNA-guided nanoparticle colloidal crystallization allows for the formation of micrometer-scale single-crystal body-centered cubic gold nanoparticle superlattices, with dye molecules coupled to the DNA strands that link the particles together, in the form of a rhombic dodecahedron. Encapsulation in silica allows one to create robust architectures with the plasmonically active particles and dye molecules fixed in space. At the micrometer scale, the anisotropic rhombic dodecahedron crystal habit couples with photonic modes to give directional light emission. At the nanoscale, the interaction between the dye dipoles and surface plasmons can be finely tuned by coupling the dye molecules to specific sites of the DNA particle-linker strands, thereby modulating dye-nanoparticle distance (three different positions are studied). The ability to control dye position with subnanometer precision allows one to systematically tune plasmon-excition interaction strength and decay lifetime, the results of which have been supported by electrodynamics calculations that span length scales from nanometers to micrometers. The unique ability to control surface plasmon/exciton interactions within such superlattice microcavities will catalyze studies involving quantum optics, plasmon laser physics, strong coupling, and nonlinear phenomena.

  5. 36 CFR 910.31 - High architectural quality.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... architectural quality. Development must maintain a uniformly high standard of architecture, representative of... architectural treatment of new buildings, particularly in terms of massing, facade design (including...

  6. 36 CFR 910.31 - High architectural quality.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... architectural quality. Development must maintain a uniformly high standard of architecture, representative of... architectural treatment of new buildings, particularly in terms of massing, facade design (including...

  7. Extraction of high-quality RNA from human articular cartilage.

    PubMed

    Le Bleu, Heather K; Kamal, Fadia A; Kelly, Meghan; Ketz, John P; Zuscik, Michael J; Elbarbary, Reyad A

    2017-02-01

    Extracting high-quality RNA from articular cartilage is challenging due to low cellularity and high proteoglycan content. This problem hinders efficient application of RNA sequencing (RNA-seq) analysis in studying cartilage homeostasis. Here we developed a method that purifies high-quality RNA directly from cartilage. Our method optimized the collection and homogenization steps so as to minimize RNA degradation, and modified the conventional TRIzol protocol to enhance RNA purity. Cartilage RNA purified using our method has appropriate quality for RNA-seq experiments including an RNA integrity number of ∼8. Our method also proved efficient in extracting high-quality RNA from subchondral bone.

  8. Motivating medical employees toward high quality work.

    PubMed

    Zinober, J W

    1992-01-01

    In her continuing series on human relation, Joan Wagner Zinober, Ph.D., M.B.A., discusses the intricacies of motivating medical staff. This article looks at the principles of motivation and provides ideas for improving the quality and quantity of employee work.

  9. 36 CFR 910.31 - High architectural quality.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false High architectural quality. 910.31 Section 910.31 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION... architectural quality. Development must maintain a uniformly high standard of architecture, representative...

  10. 36 CFR 910.31 - High architectural quality.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false High architectural quality. 910.31 Section 910.31 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION... architectural quality. Development must maintain a uniformly high standard of architecture, representative...

  11. 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.

  12. 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.

  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.

  14. 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.

  15. 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.

  16. Indoor Air Quality in High Performance Schools

    EPA Pesticide Factsheets

    High performance schools are facilities that improve the learning environment while saving energy, resources, and money. The key is understanding the lifetime value of high performance schools and effectively managing priorities, time, and budget.

  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.

  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. 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…

  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. Local observation and spectroscopy of optical modes in an active photonic-crystal microcavity.

    PubMed

    Louvion, N; Gérard, D; Mouette, J; de Fornel, F; Seassal, C; Letartre, X; Rahmani, A; Callard, S

    2005-03-25

    We report the direct, room-temperature, near-field mapping and spectroscopy of the optical modes of a photonic-crystal microcavity containing quantum wells. We use a near-field optical probe to reveal the imprint of the cavity mode structure on the quantum-well emission. Furthermore, near-field spectroscopy allows us to demonstrate the strong spatial and spectral dependence of the coupling between the sources and the microcavity. This knowledge will be essential in devising future nanophotonic devices.

  2. Cooling and Laser-Induced Fluorescence of Electronically-Excited He2 in a Supersonic Microcavity Plasma Jet

    NASA Astrophysics Data System (ADS)

    Su, Rui; Mironov, Andrey; Houlahan, Thomas, Jr.; Eden, J. Gary; LaboratoryOptical Physics; Engineering Team

    2016-09-01

    Laser-induced fluorescence (LIF) resulting from transitions between different electronic states of helium dimers generated within a microcavity plasma jet was studied with rotational resolution. In particular, the d3Σu+ , e3Πg and f3Σu+ states, all having electronic energies above 24 eV, are populated by a microplasma in 4 bar of helium gas and rotationally cooled through supersonic expansion. Analysis of two dimensional maps (spectrograms) of dimer emission spectra as a function of distance from the nozzle orifice indicates collisional coupling during the expansion between the lowest rotational levels of the e3Πg , f3Σu+ states and high rotational levels (around N=11) of the d3Σu+ state (all of which are in the v = 0 vibrational state). In an attempt to verify the coupling, a scanning dye laser (centered near 596 nm) pumps the b3Πg -> f3Σu+ transition of the molecule several hundred micrometers downstream of the nozzle. As a result, the emission intensities of relevant rotational lines are observed to be enhanced. This research shows the potential of utilizing microcavity plasma jets as a tool to study and manipulate the collisional dynamics of highly-excited diatomic molecules.

  3. High-quality continuous random networks

    NASA Astrophysics Data System (ADS)

    Barkema, G. T.; Mousseau, Normand

    2000-08-01

    The continuous random network (CRN) model is an idealized model for perfectly coordinated amorphous semiconductors. The quality of a CRN can be assessed in terms of topological and configurational properties, including coordination, bond-angle distributions, and deformation energy. Using a variation on the sillium approach proposed 14 years ago by Wooten, Winer, and Weaire, we present 1000-atom and 4096-atom configurations with a degree of strain significantly less than the best CRN available at the moment and comparable to experimental results. The low strain is also reflected in the electronic properties. The electronic density of state obtained from ab initio calculation shows a perfect band gap, without any defect, in agreement with experimental data.

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

    PubMed

    Zhou, Xin; Chong, Y D

    2016-04-04

    We perform a theoretical study of the nonlinear dynamics of nonlinear optical isolator devices based on coupled microcavities with gain and loss. This reveals 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 transition into the PT -broken phase of the linear system. When the couplings to the external ports are unequal, the isolation ratio exhibits an abrupt jump at the transition point, whose magnitude is given by the ratio of the couplings. This phenomenon could be exploited to realize an actively controlled nonlinear optical isolator, in which strong optical isolation can be turned on and off by tiny variations in the inter-resonator separation.

  5. Optical switching of polariton density patterns in a semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Kwong, N. H.; Tsang, C. Y.; Luk, Samuel M. H.; Tse, Y. C.; Chan, Chris K. P.; Lewandowski, P.; Leung, P. T.; Schumacher, Stefan; Binder, R.

    2017-03-01

    Phase-conjugate scattering can trigger modulational instabilities in a fluid of exciton-polaritons created in a pumped semiconductor quantum-well microcavity. These instabilities can settle into density patterns, e.g. hexagons and stripes, which produce corresponding patterns in the emitted light. The density patterns can be switched by relatively weak control optical beams. This paper reviews progress in our theoretical understanding of the physical processes that regulate the competitions among various patterns and drive the optical switching. Simulation results of pattern switching using a microscopic model of polariton dynamics are shown, and the mechanisms underlying competitions and switching are analyzed using reduced models that restrict the polariton motions to a limited number of relevant modes. We also briefly indicate the effects of the spin dependence of the polariton dynamics on the patterns.

  6. On-Chip Optical Nonreciprocity Using an Active Microcavity

    PubMed Central

    Jiang, Xiaoshun; Yang, Chao; Wu, Hongya; Hua, Shiyue; Chang, Long; Ding, Yang; Hua, Qian; Xiao, Min

    2016-01-01

    Optically nonreciprocal devices provide critical functionalities such as light isolation and circulation in integrated photonic circuits for optical communications and information processing, but have been difficult to achieve. By exploring gain-saturation nonlinearity, we demonstrate on-chip optical nonreciprocity with excellent isolation performance within telecommunication wavelengths using only one toroid microcavity. Compatible with current complementary metal-oxide-semiconductor process, our compact and simple scheme works for a very wide range of input power levels from ~10 microwatts down to ~10 nanowatts, and exhibits remarkable properties of one-way light transport with sufficiently low insertion loss. These superior features make our device become a promising critical building block indispensable for future integrated nanophotonic networks. PMID:27958356

  7. On-Chip Optical Nonreciprocity Using an Active Microcavity

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoshun; Yang, Chao; Wu, Hongya; Hua, Shiyue; Chang, Long; Ding, Yang; Hua, Qian; Xiao, Min

    2016-12-01

    Optically nonreciprocal devices provide critical functionalities such as light isolation and circulation in integrated photonic circuits for optical communications and information processing, but have been difficult to achieve. By exploring gain-saturation nonlinearity, we demonstrate on-chip optical nonreciprocity with excellent isolation performance within telecommunication wavelengths using only one toroid microcavity. Compatible with current complementary metal-oxide-semiconductor process, our compact and simple scheme works for a very wide range of input power levels from ~10 microwatts down to ~10 nanowatts, and exhibits remarkable properties of one-way light transport with sufficiently low insertion loss. These superior features make our device become a promising critical building block indispensable for future integrated nanophotonic networks.

  8. 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°.

  9. 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.

  10. 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.

  11. The High Flying Leadership Qualities: What Matters the Most

    DTIC Science & Technology

    2016-04-01

    IATIO N THE HIGH FLYING Leadership Qualities: What Matters the Most? Col Robert L. Tremaine, USAF (Ret.) Like many U.S. companies, the Department...level leaders (SLLs), or equivalent offer a gateway to learn more about what leadership qualities matter to them. At the Defense Acquisition University...level managers (SLMs) have to say about the leadership qualities that matter most during their own continuing professional development journey

  12. High quality tunable Brillouin optoelectronic oscillator

    NASA Astrophysics Data System (ADS)

    Mousa, Mohamed; Ahmed, Mahmoud H.; Hassan, Kamel M. M.; Abouelatta, Mohamed; Afifi, Abdelrahman E.

    2016-09-01

    An optical scheme to improve the quality of an RF signal is proposed. The 6 dB linewidth is reduced to sub hertz and the low frequency noise below 1 KHz is reduced about 10 dB. The scheme utilizes a Brillouin-semiconductor optical amplifier (SOA) ring laser fitted with an RF intensity modulator and an APD detector. The experimental results show cavity modes with FSR of 30.57 KHz due to Brillouin fiber length of 6.6 km and 6 dB bandwidth of 780 mHz typical of Brillouin lasers. The gain of the SOA balances out most of the losses in the ring mainly that due to the RF modulator. The modulated optical signal beats at the APD. The optical loop acts as a cavity filter to the RF signal. A jitter in the cavity resonances due to temperature variations is completely eliminated from the output beat signal. There is a 10 dB increase in the phase noise at the FSR frequency and its harmonics. The setup is tested with signals generated by different sources and to frequencies up to 10 GHz, the limit of the APD. Sources with RF linewidth less than the optical FSR produces one output mode with sub-hertz line width. For larger line width signals more than one RF frequency is produced, separated by the FSR, each showing the Brillouin linewidth.

  13. 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

  14. Developing High-Quality Teachers: Teacher Evaluation for Improvement

    ERIC Educational Resources Information Center

    Looney, Janet

    2011-01-01

    As countries aim to ensure high achievement for all students, improving and sustaining the quality of the teacher workforce is a vital policy priority. Several studies have found that well-designed teacher evaluation systems, aligned with professional learning and development, can contribute to improvements in the quality of teaching and raise…

  15. 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…

  16. Comparative performance of wavelets and JPEG coders at high quality

    NASA Astrophysics Data System (ADS)

    Algazi, V. Ralph; Estes, Robert R., Jr.

    1997-04-01

    In recent work, we have examined the performance of wavelet coders using a perceptually relevant image quality metric, the picture quality scale (PQS). In that study, we considered some of the design options available with respect to choice of wavelet basis, quantizer, and method for error- free encoding of the quantized coefficients, including the EZW methodology. A specific combination of these design options provides the best trade off between performance and PQS quality. Here, we extend this comparison by evaluating the performance of JPEG and the previously chosen optimal wavelet scheme, focusing principally on the high quality range.

  17. 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.

  18. Promoting High-Quality Family Child Care: A Policy Perspective for Quality 2000.

    ERIC Educational Resources Information Center

    Modigliani, Kathy

    Although family child care has the potential to offer young children individual attention and customized, educational programs to help them thrive, the quality of these programs is dependent upon a workforce that is at the bottom of the occupational status and pay hierarchy. This report examines ways to promote high quality in family child care…

  19. Emblems of Quality in Higher Education. Developing and Sustaining High-Quality Programs.

    ERIC Educational Resources Information Center

    Haworth, Jennifer Grant; Conrad, Clifton F.

    This book proposes an "engagement" theory of program quality to evaluate and improve higher education programs at all degree levels. Based on interviews with 781 participants in a national study of Masters degree programs, it focuses on the interactive roles of students, faculty, and administrators in developing high-quality programs…

  20. Photon echoes from (In,Ga)As quantum dots embedded in a Tamm-plasmon microcavity

    NASA Astrophysics Data System (ADS)

    Salewski, M.; Poltavtsev, S. V.; Kapitonov, Yu. V.; Vondran, J.; Yakovlev, D. R.; Schneider, C.; Kamp, M.; Höfling, S.; Oulton, R.; Akimov, I. A.; Kavokin, A. V.; Bayer, M.

    2017-01-01

    We report on the coherent optical response from an ensemble of (In,Ga)As quantum dots (QDs) embedded in a planar Tamm-plasmon microcavity with a quality factor of approximately 100. Significant enhancement of the light-matter interaction is demonstrated under selective laser excitation of those quantum dots which are in resonance with the cavity mode. The enhancement is manifested through Rabi oscillations of the photon echo, demonstrating coherent control of excitons with picosecond pulses at intensity levels more than an order of magnitude smaller as compared with bare quantum dots. The decay of the photon echo transients is weakly changed by the resonator, indicating a small decrease of the coherence time T2 which we attribute to the interaction with the electron plasma in the metal layer located close (40 nm) to the QD layer. Simultaneously we see a reduction of the population lifetime T1, inferred from the stimulated photon echo, due to an enhancement of the spontaneous emission by a factor of 2, which is attributed to the Purcell effect, while nonradiative processes are negligible, as confirmed from time-resolved photoluminescence.

  1. 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.

  2. 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.

  3. 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

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

    PubMed

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

    2014-03-01

    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.

  5. 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

  6. 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.

  7. Broken symmetry dielectric resonators for high quality factor Fano metasurfaces

    SciTech Connect

    Campione, Salvatore; Liu, Sheng; Basilio, Lorena I.; Warne, Larry K.; Langston, William L.; Luk, Ting S.; Wendt, Joel R.; Reno, John L.; Keeler, Gordon A.; Brener, Igal; Sinclair, Michael B.

    2016-10-25

    We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieves a quality factor of ~1300 at ~10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (~1 μm): a silicon-based implementation that achieves a quality factor of ~350; and a gallium arsenide-based structure that achieves a quality factor of ~600, the highest near-infrared quality factor experimentally demonstrated to date with this kind of metasurface. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. Here, we envision that combining high quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.

  8. Broken symmetry dielectric resonators for high quality factor Fano metasurfaces

    DOE PAGES

    Campione, Salvatore; Liu, Sheng; Basilio, Lorena I.; ...

    2016-10-25

    We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurfacemore » that achieves a quality factor of ~1300 at ~10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (~1 μm): a silicon-based implementation that achieves a quality factor of ~350; and a gallium arsenide-based structure that achieves a quality factor of ~600, the highest near-infrared quality factor experimentally demonstrated to date with this kind of metasurface. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. Here, we envision that combining high quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.« less

  9. 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.

  10. Condensation phase diagram of cavity polaritons in GaN-based microcavities: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Levrat, Jacques; Butté, Raphaël; Feltin, Eric; Carlin, Jean-François; Grandjean, Nicolas; Solnyshkov, Dmitry; Malpuech, Guillaume

    2010-03-01

    The evolution of the polariton condensation threshold (Pthr) under incoherent optical pumping is investigated both theoretically and experimentally over a wide range of temperatures (4-340 K) and exciton-cavity photon detunings (-120-0meV) in a multiple quantum-well GaN-based microcavity. The condensation phase diagram of these bosonic quasiparticles is first theoretically described within the framework of Bose-Einstein condensation of polaritons in the thermodynamic limit. Then a qualitative picture of cavity polariton relaxation kinetics including the impact of detuning and temperature is given before introducing a modeling of cavity polariton relaxation kinetics with semiclassical Boltzmann equations. The results of the theoretical modeling are finally compared with systematic measurements of Pthr . At low temperature and negative detunings, the polariton gas is far from thermal equilibrium and the condensation threshold is governed by the efficiency of the relaxation kinetics of the particles. Conversely, at high temperature and for less negative detunings, the relaxation kinetics is efficient enough to allow the achievement of a thermal polariton distribution function with a critical density for condensation given by the thermodynamic theory of Bose-Einstein condensation. For temperatures ranging between ˜140 and 340 K, an optimum detuning is found experimentally, where the condensation threshold power is minimized. At high temperatures, polariton detrapping effects from the bottom of the trap formed in k∥ space by the lower polariton branch are found to play a supplementary role among the processes governing Pthr .

  11. A procedure for high resolution satellite imagery quality assessment.

    PubMed

    Crespi, Mattia; De Vendictis, Laura

    2009-01-01

    Data products generated from High Resolution Satellite Imagery (HRSI) are routinely evaluated during the so-called in-orbit test period, in order to verify if their quality fits the desired features and, if necessary, to obtain the image correction parameters to be used at the ground processing center. Nevertheless, it is often useful to have tools to evaluate image quality also at the final user level. Image quality is defined by some parameters, such as the radiometric resolution and its accuracy, represented by the noise level, and the geometric resolution and sharpness, described by the Modulation Transfer Function (MTF). This paper proposes a procedure to evaluate these image quality parameters; the procedure was implemented in a suitable software and tested on high resolution imagery acquired by the QuickBird, WorldView-1 and Cartosat-1 satellites.

  12. A Procedure for High Resolution Satellite Imagery Quality Assessment

    PubMed Central

    Crespi, Mattia; De Vendictis, Laura

    2009-01-01

    Data products generated from High Resolution Satellite Imagery (HRSI) are routinely evaluated during the so-called in-orbit test period, in order to verify if their quality fits the desired features and, if necessary, to obtain the image correction parameters to be used at the ground processing center. Nevertheless, it is often useful to have tools to evaluate image quality also at the final user level. Image quality is defined by some parameters, such as the radiometric resolution and its accuracy, represented by the noise level, and the geometric resolution and sharpness, described by the Modulation Transfer Function (MTF). This paper proposes a procedure to evaluate these image quality parameters; the procedure was implemented in a suitable software and tested on high resolution imagery acquired by the QuickBird, WorldView-1 and Cartosat-1 satellites. PMID:22412312

  13. 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…

  14. Quality Assurance and Statistics. High-Technology Training Module.

    ERIC Educational Resources Information Center

    Wirsbinski, William

    This high technology quality assurance and statistics training module is a part of the statistics unit for an algebra I or algebra II course. This module fits into high school math classes in which students compute and display measures of central tendency and variability. The module contains a description, objectives, and content outline--phase I…

  15. Process to Continuously Melt, Refine and Cast High Quality Steel

    SciTech Connect

    2005-09-01

    The purpose of this project is to conduct research and development targeted at designing a revolutionary steelmaking process. This process will deliver high quality steel from scrap to the casting mold in one continuous process and will be safer, more productive, and less capital intensive to build and operate than conventional steelmaking. The new process will produce higher quality steel faster than traditional batch processes while consuming less energy and other resources.

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

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-12-18

    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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-12-01

    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.

  19. Quality of service on high-speed data networks

    NASA Astrophysics Data System (ADS)

    Barbero, Ezio; Antonelli, Ferruccio

    1995-02-01

    Since the beginning of this century the issue of `quality' has been gaining increasing importance in a number of fields of human activities. For telecommunication services, too, the quality perceived by customers has been taken into account early on as an issue of strategic importance. Whilst for telephony the Quality of Service (QoS) has been already investigated and identified in terms of parameters and related test methodology, the situation for high speed data services (i.e. CBDS/SMDS, Frame Relay, etc.), provided by means of high speed network based on Asynchronous Transfer Moe (ATM) or Metropolitan Area Network technologies, can still be considered `under study'. There is a death of experience not only in terms of measurement instruments and procedures, but also in terms of knowledge of the relationship between the QoS provided at a network level and the quality perceived by the user on his or her terminal. The complexity of the equipment involved in setting up an end-to-end solution based on high speed data communications makes the problems of knowledge and supply of quality very hard to solve. Starting from the experience gained in carrying out high- speed network field trials based on Metropolitan Area Networks and, more recently, on ATM technology, the paper mainly deals with the problem of defining, measuring and then offering a specific QoS. First, the issue of what the user expects from the `high-speed network' is addressed. This analysis is carried out trying to gather what is peculiar to high-speed data communications from the user standpoint. Next, the focus is on how to cope with the requirements due to users' expectations, while carefully considering the basic principles of quality. Finally, a solution is proposed, starting from the experience gained from high speed networks installed in Italy.

  20. Luminescence spectra of quantum dots in microcavities. II. Fermions

    NASA Astrophysics Data System (ADS)

    Del Valle, Elena; Laussy, Fabrice P.; Tejedor, Carlos

    2009-06-01

    We discuss the luminescence spectra of coupled light-matter systems realized with semiconductor heterostructures in microcavities in the presence of a continuous, incoherent pumping, when the matter field is fermionic. The linear regime—which has been the main topic of investigation both experimentally and theoretically—converges to the case of coupling to a bosonic material field, and has been amply discussed in the first part of this work. We address here the nonlinear regime, and argue that, counter to intuition, it is better observed at low pumping intensities. We support our discussion with particular cases representative of, and beyond, the experimental state of the art. We explore the transition from the quantum to the classical regime, by decomposing the total spectrum into individual transitions between the dressed states of the light-matter coupling Hamiltonian, reducing the problem to the positions and broadenings of all possible transitions. As the system crosses to the classical limit, rich multiplet structures mapping the quantized energy levels melt and turn to cavity lasing and to an incoherent Mollow triplet in the direct exciton emission for very good structure. Less ideal figures of merit can still betray the quantum regime, with a proper balance of cavity versus electronic pumping.

  1. Photonic confinement in laterally structured metal-organic microcavities

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    We investigate the formation of optical modes in organic microcavities with an incorporated perforated silver layer. The metal leads to a formation of Tamm-plasmon-polaritons and thus separates the sample into metal-free or metal-containing areas, supporting different resonances. This mode splitting is exploited to confine photons in elliptic holes and triangular cuts, forming distinctive standing wave patterns showing the strong lateral confinement. A comparison with a Maxwell-Bloch based rate equation model clearly shows the nonlinear transition into the lasing regime. The concentration of the electric field density and inhibition of lateral loss channels in turn decreases the lasing threshold by up to one order of magnitude, to 0.1 nJ. By spectroscopic investigation of such a triangular wedge, we observe the transition from the unperturbed cavity state to a strongly confined complex transversal mode. Such a structured silver layer can be utilized in future for charge carrier injection in an electrically driven organic solid state laser.

  2. A printable color filter based on the micro-cavity incorporating a nano-grating

    NASA Astrophysics Data System (ADS)

    Ye, Yan; Xu, Fengchuan; Wu, Shangliang; Wan, Wenqiang; Huang, Wenbin; Liu, Yanhua; Pu, Donglin; Wei, Guojun; Zhou, Yun; Wang, Yanyan; Qiao, Wen; Xu, Yishen; Chen, Linsen

    2016-10-01

    A printable color filter based on the photonic micro-cavity incorporating a nanostructure is proposed, which consists of a nano-metallic grating, a dielectric layer and aluminum (Al) film. According to the resonance induced by different dielectric depths of the micro-cavity, two dielectric heights for the same resonant wavelength are chosen to form the grating heights relative to the Al film. With the contribution of the cavity resonance and the surface plasmon resonance, the proposed structure performs enhanced broadband filtering characteristics with good angular tolerance up to 48° compared to the one of the micro-cavity as well as the one of the metallic grating. Therefore, reflective filters for RGB colors are designed incorporating the proposed structure. Furthermore, for the proposed structure shows great polarization dependence even at normal incidence, it can also be utilized as an anticounterfeiting certificate.

  3. 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.

  4. Magneto-photonic crystal microcavities based on magnetic nanoparticles embedded in Silica matrix

    NASA Astrophysics Data System (ADS)

    Hocini, Abdesselam; Moukhtari, Riad; Khedrouche, Djamel; Kahlouche, Ahmed; Zamani, Mehdi

    2017-02-01

    Using the three-dimensional finite difference time domain method (3D FDTD) with perfectly matched layers (PML), optical and magneto-optical properties of two-dimensional magneto-photonic crystals micro-cavity is studied. This micro-cavity is fabricated by SiO2/ZrO2 or SiO2/TiO2 matrix doped with magnetic nanoparticles, in which the refractive index varied in the range of 1.51-1.58. We demonstrate that the Q factor for the designed cavity increases as the refractive index increases, and we find that the Q factor decreases as the volume fraction VF% due to off-diagonal elements increases. These magnetic microcavities may serve as a fundamental structure in a variety of ultra compact magneto photonic devices such as optical isolators, circulators and modulators in the future.

  5. Phase-locked coherent modes in a patterned metal-organic microcavity

    NASA Astrophysics Data System (ADS)

    Brückner, R.; Zakhidov, A. A.; Scholz, R.; Sudzius, M.; Hintschich, S. I.; Fröb, H.; Lyssenko, V. G.; Leo, K.

    2012-05-01

    Organic microcavities offer tantalizing prospects for studying the interactions of light and matter. For electrical excitation of these processes, electrodes must be integrated. However, the large absorption properties of metals are generally considered fatal for optical coherence. With this in mind, we embedded a thin silver grating into an organic microcavity to generate periodic arrays of localized cavity modes and metal-based Tamm plasmon polaritons. These excited states are capable of phase coupling across the grating. At room temperature and under non-resonant pumping, we selectively stimulated coherent emission from in- and out-of-phase locked arrays. We show that an absorptive metal inside an optical cavity is compatible with coherent emission. Most importantly, the inherently low residual absorption of the organic layer enables coherence to spread over macroscopic distances, even at room temperature. Our strategy of embedding metal patterns into an organic microcavity yields a viable route towards electrically driven organic solid-state lasers.

  6. 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.

  7. Diode-pumped distributed-feedback dye laser with an organic inorganic microcavity

    NASA Astrophysics Data System (ADS)

    Sakata, H.; Yamashita, K.; Takeuchi, H.; Tomiki, M.

    2008-08-01

    We present a diode-pumped microcavity dye laser composed of a top organic reflector and a bottom inorganic reflector. The top organic reflector consists of alternate thin films of cellulose acetate and poly(N-vinylcarbazole) doped with coumarin 540A to construct a distributed-feedback (DFB) resonator. Pumped directly by an InGaN-based blue laser diode (LD) with a pulse duration of 4 ns, the microcavity dye laser exhibited a single-mode oscillation at 563 nm with a threshold pump LD power of 290 mW/pulse. The emission of the microcavity dye laser was measured through an optical fiber, resulting in a peak power of 2.5 mW for a pump LD power of 320 mW.

  8. 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.

  9. Physician incentives to improve quality and the delivery of high quality ambulatory medical care

    PubMed Central

    Bishop, Tara F.; Federman, Alex D.; Ross, Joseph S.

    2012-01-01

    Objective To determine the prevalence of physician incentives for quality and to test the hypothesis that quality of ambulatory medical care is better by physicians with these incentives. Study Design Cross-sectional study using data from the National Ambulatory Medical Care Survey Method We examined the association between physician compensation based on quality, physician compensation based on satisfaction, and public reporting of practice measures and twelve measures of high quality ambulatory care. Results Overall, 20.8% of visits were to physicians whose compensation was partially based on quality, 17.7% of visits were to physicians whose compensation was partially based on patient satisfaction, and 10.0% of visits were to physicians who publicly reported performance measures. Quality of ambulatory care varied: weight reduction counseling occurred in 12.0% of preventative care visits by obese patients whereas urinalysis was not performed in 93.0% of preventative care visits. In multivariable analyses, there were no statistically significant associations between compensation for quality and delivery of any of the 12 measures, nor between compensation for satisfaction and 11 of the 12 measures; the exception was BMI screening in preventative visits (47.8% vs. 56.2%, adjusted p=0.004). There was also no statistically significant association between public reporting and delivery of 11 of 12 measures; the exception was weight reduction counseling for overweight patients (10.0% vs. 25.5%, adjusted p=0.01). Conclusions We found no consistent association between incentives for quality and 12 measures of high quality ambulatory care. PMID:22554038

  10. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities

    PubMed Central

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C.

    2016-01-01

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths. PMID:27721454

  11. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities

    NASA Astrophysics Data System (ADS)

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C.

    2016-10-01

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths.

  12. Cooling of Electronically-Excited He2 Molecules in a Microcavity Plasma Jet

    NASA Astrophysics Data System (ADS)

    Su, Rui; Houlahan, Thomas J., Jr.; Eden, J. Gary

    2016-06-01

    Helium dimers in the d3Σ+u excited electronic state with potential energy >24 eV and radiative lifetime of 25 ns have been generated in a microcavity plasma jet and rotationally cooled by supersonic expansion in vacuum. The dynamic process of cooling is recorded by imaging the axis of expansion onto the slit of Czerny-Turner spectrometer, yielding spatial-temporal spectrograms of d3Σ+u→b3Πg (v', v'')=(0, 0) emission. Analysis of the data shows the spatial-temporal evolution of the rotational temperature to be a damped sinusoid that reaches a minimum value of 100K. This reproducible behavior is attributed to the reflection of electrons from a virtual cathode located downstream of the nozzle and indicates that the spatially-averaged electron density is 108 cm-3. We present this observed rotational temperature oscillation during the supersonic cooling process as an example of the potential of our supersonic microplasma expansion as a tool to explore physical dynamics in diatomic molecules having high excitation energies and small lifetimes.

  13. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities.

    PubMed

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C

    2016-10-10

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths.

  14. 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).

  15. High quality factor etchless silicon photonic ring resonators.

    PubMed

    Luo, Lian-Wee; Wiederhecker, Gustavo S; Cardenas, Jaime; Poitras, Carl; Lipson, Michal

    2011-03-28

    We demonstrate high quality factor etchless silicon photonic ring resonators fabricated by selective thermal oxidation of silicon without the silicon layer being exposed to any plasma etching throughout the fabrication process. We achieve a high intrinsic quality factor of 510,000 in 50 µm-radius ring resonators, corresponding to a ring loss of 0.8 dB/cm. The device has a total chip insertion loss of 2.5 dB, achieved by designing etchless silicon inverse nanotapers at both the input and output of the chip.

  16. [Spectrum characterization and fine structure of copper phthalocyanine-doped TiO2 microcavities].

    PubMed

    Liu, Cheng-lin; Zhang, Xin-yi; Zhong, Ju-hua; Zhu, Yi-hua; He, Bo; Wei, Shi-qiang

    2007-10-01

    Copper phthalocyanine-doped TiO2 microcavities were fabricated by chemistry method. Their spectrum characterization was studied by Fourier transform infrared (FTIR) and Raman spectroscopy, and their fine structure was analyzed by X-ray absorption fine structure (XAFS). The results show that there is interaction of copper phthalocyanine (CuPc) and TiO2 microcavities after TiO2 microcavities was doped with CuPc. For example, there is absorption at 900.76 cm(-1) in FTIR spectra, and the "red shift" of both OH vibration at 3392.75 cm(-1) and CH vibration at 2848.83 cm(-1). There exist definite peak shifts and intensity changes in infrared absorption in the C-C or C-N vibration in the planar phthalocyanine ring, the winding vibration of C-H inside and C-N outside plane of benzene ring. In Raman spectrum, there are 403.4, 592.1 and 679.1 cm(-1) characterized peaks of TiO2 in CuPc-doped TiO2 microcavities, but their wave-numbers show shifts to anatase TiO2. The vibration peaks at 1586.8 and 1525.6 cm(-1) show that there exists the composite material of CuPc and TiO2. These changes are related to the plane tropism of the molecule structure of copper phthalocyanine. XAFS showed tetrahedron TiO4 structure of Ti in TiO2 microcavities doped with copper phthalocyanine, and the changes of inner "medial distances" and the surface structure of TiO2 microcavities.

  17. 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

  18. 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

  19. An All Fiber Intrinsic Fabry-Perot Interferometer Based on an Air-Microcavity

    PubMed Central

    Jáuregui-Vázquez, Daniel; Estudillo-Ayala, Julián M.; Rojas-Laguna, Roberto; Vargas-Rodríguez, Everardo; Sierra-Hernández, Juan M.; Hernández-García, Juan C.; Mata-Chávez, Ruth I.

    2013-01-01

    In this work an Intrinsic Fabry-Perot Interferometer (IFPI) based on an air-microcavity is presented. Here the air microcavity, with silica walls, is formed at a segment of a hollow core photonic crystal fiber (HCPCF), which is fusion spliced with a single mode fiber (SMF). Moreover, the spectral response of the IFPI is experimentally characterized and some results are provided. Finally, the viability to use the IFPI to implement a simple, compact size, and low cost refractive index sensor is briefly analyzed. PMID:23673676

  20. Black phosphorus-based one-dimensional photonic crystals and microcavities

    NASA Astrophysics Data System (ADS)

    Kriegel, Ilka; Toffanin, Stefano; Scotognella, Francesco

    2016-11-01

    The latest achievements in the fabrication of black phosphorus thin layers, towards the technological breakthrough of a phosphorene atomically thin layer, are paving the way for a their employment in electronics, optics, and optoelectronics. In this work, we have simulated the optical properties of one-dimensional photonic structures, i.e. photonic crystals and microcavities, in which few-layer black phosphorus is one of the components. The insertion of the 5 nm black phosphorous layers leads to a photonic band gap in the photonic crystals and a cavity mode in the microcavity interesting for light manipulation and emission enhancement.

  1. 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.

  2. Microcavity organic light-emitting diodes for strongly directed pure red, green, and blue emissions

    NASA Astrophysics Data System (ADS)

    Tokito, Shizuo; Tsutsui, Tetsuo; Taga, Yasunori

    1999-09-01

    In this article we demonstrate strongly directed pure red, green, and blue emissions in the organic light-emitting diodes (OLEDs) with a planar microcavity defined by a pair of dielectric mirror and a metal mirror. By careful control of the cavity mode and the position of the resonance wavelength, the strong directionality in the forward direction as well as the spectral narrowing and the intensity enhancement are realized in the microcavity OLEDs. The intensity enhancements at the resonance wavelength are 1.5-5 compared to the noncavity OLEDs, and the chromaticity coordinates of the emission colors are the ideal primary colors. The experimental results are compared to theoretically calculated ones.

  3. 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.

  4. 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

    2015-07-30

    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.

  5. 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.

  6. 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.

  7. 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.

  8. Monitoring reservoir water quality with Formosat-2 high spatiotemporal imagery.

    PubMed

    Chang, Chih-Hua; Liu, Cheng-Chien; Wen, Ching-Gung; Cheng, I-Fan; Tam, Chi-Kin; Huang, Ching-Shiang

    2009-11-01

    Water reservoirs are the primary source of freshwater for most cities around the world. To monitor the dynamic changes in reservoir water quality, however, we need an innovative platform that is able to observe the entire reservoir with both high-spatial- and high-temporal-resolution. Formosat-2 is the first commercial satellite dedicated to site surveillance with a high-spatial-resolution sensor placed in a daily revisit orbit (2 m in panchromatic and 8 m in multispectral). In this research, we developed two empirical algorithms to map the water contents of Chlorophyll-a (Chl-a) and suspended solids (SS) from Formosat-2 multispectral imagery. These algorithms are derived from a total of 53 pairs of water-quality and surface-reflectance data collected during 14 field campaigns at Tsengwen Reservoir from 2005 to 2006. A total of 15 Formosat-2 images were selected from all available images of Tsengwen Reservoir taken in 2006 to generate water quality maps of Chl-a and SS using our new algorithms. Results from this study indicate that the Chl-a and SS concentrations can be retrieved from Formosat-2 imagery with deviations of 56% and 43%, respectively. This is the first time that the reservoir water quality can be mapped from a high-spatial-resolution satellite image at such a high-temporal-resolution. To facilitate the administration of water resources, this research encourages the application of Formosat-2 high spatiotemporal imagery in identifying areas of poor water quality and monitoring the dispersal pattern of pollutant plumes.

  9. 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.

  10. 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

  11. Cultivating High-Quality Teaching through Induction and Mentoring

    ERIC Educational Resources Information Center

    Bartell, Carol A.

    2004-01-01

    The first few years of teaching are the most challenging. During these years, teachers are most likely to become discouraged and disillusioned. Yet these early years are also the time when teachers establish practices that last throughout their careers. This book focuses on new teachers' needs while emphasizing high-quality teaching through the…

  12. Measuring the Impact of High Quality Instant Feedback on Learning

    ERIC Educational Resources Information Center

    Nutbrown, Stephen; Higgins, Colin; Beesley, Su

    2016-01-01

    This paper examines the impact of a novel assessment technique that has been used to improve the feedback given to second year Computer Science students at the University of Nottingham. Criteria for effective, high quality feedback are discussed. An automated marking system (The Marker's Apprentice--TMA) produces instant feedback in synergy with…

  13. Total Quality Management (TQM): High School/College Course Material.

    ERIC Educational Resources Information Center

    Leigh, David

    This Total Quality Management (TQM) course was designed to introduce students to the principles and tools of TQM in a full-semester course in high schools or community colleges. The course includes all the competencies found in TQM and is intended to be taught with an interactive method in which students are involved in the learning process. This…

  14. 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...

  15. 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…

  16. Extraction of high-quality RNA from rubber tree leaves.

    PubMed

    Deng, Liu-Hong; Luo, Ming-Wu; Zhang, Chun-Fa; Zeng, Hui-Cai

    2012-01-01

    A specific technique capable of producing high-quality RNA for rapid amplification of cDNA ends (RACE) was established for challenging tissues: leaves of the rubber tree. Total RNA was extracted by cetyltrimethylammonium bromide (CTAB)-LiCl combined with TRIzol reagent. The isolated RNA was highly intact. With RNA as template, full-length cDNA was obtained (NCBI, AY461413) by RACE.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. High Quality Factor Mechanical Resonators Based on WSe2 Monolayers

    PubMed Central

    2016-01-01

    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 × 104 at liquid nitrogen temperature and 4.7 × 104 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

  3. High quality videoconferencing system for wide area IP networks

    NASA Astrophysics Data System (ADS)

    Qiu, Ruibiao; Kuhns, Fred; Cox, Jerome R., Jr.; Horn, Craig

    2002-12-01

    High quality video conferencing is an efficient tool for interactive scientific collaboration in the research community, especially for researchers separated by substantial distance. With the wide deployment of broadband wide area IP networks such as the Internet2, there is an increasing demand for improved remote collaboration with these networks. In order to make the high quality video-conferencing toolkits for local high-speed networks available over wide area IP networks, issues that are usually insignificant on local area networks must be considered. To this end, we have developed called Adaptation Layer Translator (ALX) in order to address these issues and solve the problems associated with real-time video and audio transmission over wide area IP networks. A conference control protocol is developed to coordinate the participants in an ALX-based conference. The ALX is also designed to be able to adapt to heterogeneous network environments at different deployment sites.

  4. Two-Phase Flow Pressure Drop of High Quality Steam

    SciTech Connect

    Curtis, J. M.; Coffield, R. D.

    2001-10-01

    Two-phase pressure drop across a straight test pipe was experimentally determined for high Reynolds (Re) number steam flow for a flow quality range of 0.995 to 1.0. The testing described has been performed in order to reduce uncertainties associated with the effects of two-phase flow on pressure drop. Two-phase flow develops in steam piping because a small fraction of the steam flow condenses due to heat loss to the surroundings. There has been very limited two-phase pressure drop data in open literature for the tested flow quality range. The two-phase pressure drop data obtained in this test has enabled development of a correlation between friction factor, Reynolds number, and flow quality.

  5. FDTD and transfer matrix methods for evaluating the performance of photonic crystal based microcavities for exciton-polaritons

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Cheng; Byrnes, Tim

    2016-11-01

    We investigate alternative microcavity structures for exciton-polaritons consisting of photonic crystals instead of distributed Bragg reflectors. Finite-difference time-domain simulations and scattering transfer matrix methods are used to evaluate the cavity performance. The results are compared with conventional distributed Bragg reflectors. We find that in terms of the photon lifetime, the photonic crystal based microcavities are competitive, with typical lifetimes in the region of ∼20 ps being achieved. The photonic crystal microcavities have the advantage that they are compact and are frequency adjustable, showing that they are viable to investigate exciton-polariton condensation physics.

  6. Efficient numerical method for analyzing optical bistability in photonic crystal microcavities.

    PubMed

    Yuan, Lijun; Lu, Ya Yan

    2013-05-20

    Nonlinear optical effects can be enhanced by photonic crystal microcavities and be used to develop practical ultra-compact optical devices with low power requirements. The finite-difference time-domain method is the standard numerical method for simulating nonlinear optical devices, but it has limitations in terms of accuracy and efficiency. In this paper, a rigorous and efficient frequency-domain numerical method is developed for analyzing nonlinear optical devices where the nonlinear effect is concentrated in the microcavities. The method replaces the linear problem outside the microcavities by a rigorous and numerically computed boundary condition, then solves the nonlinear problem iteratively in a small region around the microcavities. Convergence of the iterative method is much easier to achieve since the size of the problem is significantly reduced. The method is presented for a specific two-dimensional photonic crystal waveguide-cavity system with a Kerr nonlinearity, using numerical methods that can take advantage of the geometric features of the structure. The method is able to calculate multiple solutions exhibiting the optical bistability phenomenon in the strongly nonlinear regime.

  7. Radar Backscatter and Coherence Information Supporting High Quality Urban Mapping

    NASA Astrophysics Data System (ADS)

    Fischer, P.; Perski, Z.; Wannemacher, S.

    2004-06-01

    The potential of a synergetic use of different data sources for a high quality mapping of urban features is described in this paper. In the urban application domain, beside the different EO-sensors and products there are a lot of high resolution and high quality GIS- and digital map databases available (e.g. ATKIS in Germany), provided by public authorities but also by private industry. Fusing this ground-based data with remotely sensed information is resulting in high quality thematic datasets. Using ATKIS Geodata, IKONOS multispectral- and ERS-SAR / ENVISAT-ASAR data as input, in the research described we implemented a GIS-based expert system to derive in a first step the degree of sealing in the regions of interest (ROI). Joining the reclassified ATKIS-data with a vegetation index, the backscatter- and the coherence information, the output of the processing chain is a vector data layer dividing the ROI in different classes of sealing. Adding the SAR-/ASAR derived backscatter and coherence data into the spatial analysis results in a partial improvement of the classification process, especially in rural areas.

  8. Towards high-quality optical ceramic YAG fibers for high-energy laser (HEL) applications

    NASA Astrophysics Data System (ADS)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian

    2012-06-01

    There is a critical demand for high quality, transparent ceramic YAG fibers for high powered fiber lasers. The production of laser quality ceramic fibers hinges on advanced ceramic processing technology, along with the availability of highly sinterable powder with high phase and chemical purity. These two fundamental technologies have been successfully developed at UES. Nd (1.1 a/o) and Yb (1.0 a/o)-doped yttrium aluminum garnet (YAG) fibers with high optical quality were produced by combining UES's tailored powders with advanced consolidation processes including fiber extrusion and vacuum sintering. The as-sintered and as-annealed fibers, approximately 30 microns in diameter, appeared transparent and successfully transmitted laser beams; further development will allow for the production of doped ceramic YAG fiber lasers for advanced high power and high energy fiber laser systems.

  9. 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

    2013-10-15

    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.

  10. 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.

  11. High-quality microcutting in silicon by advanced laser technology

    NASA Astrophysics Data System (ADS)

    Gallus, E.; Castelli, Paolo

    2003-11-01

    This paper reports on the potentialities of innovative lasers in microcutting of silicon, one of the most important materials in the field of microelectronics. In recent years, novel laser based micromachining methods have played an increasingly important role in the ongoing miniaturization of consumer electronics. Here, high-quality microcutting in silicon using a "green" laser, whose wavelength is readily absorbed by silicon, is presented.

  12. 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.

  13. Electrically tunable, optical microcavity based on metallized and ultra-soft PDMS gel

    NASA Astrophysics Data System (ADS)

    Franke, M.; Slowik, I.; Paschew, G.; Merkel, U.; Fröb, H.; Leo, K.; Richter, A.

    2016-04-01

    Tunable, optical microcavities (MC) gain more and more importance for display, laser or other optical applications. The setup of dielectric elastomer actuators (DEA) enables a simple integration of an optical cavity, since reflective electrodes can confine a cavity that is filled with a transparent elastomer. Applying a voltage to the electrodes leads to squeezing of the elastomer and, due to the cavity thickness decrease, the resonator modes of interfering light changes. In this work we present an electrically tunable, optical MC based on ultra-soft poly(dimethylsiloxane) (PDMS). The PDMS gel is coated on a glass substrate with a distributed Bragg reflector, an ITO bottom electrode and a flexible, highly reflective metal electrode and mirror on top. The usage of an ultra-soft PDMS gel, with a storage modulus of about 1kPa, allows to decrease the operating voltage down to a few hundred or even several ten volts. The critical step of fabrication is the metallization of the PDMS gel layer that requires a previous oxidizing surface activation to gain reflective and conductive silver based layers on top. Therefore, the effects of oxygen plasma and UV/ozone treatment on PDMS and the created metal layer were investigated intensively. The performance of the electrically tunable, optical MC is tremendously dependent from an adequate surface activation and structuring of the top electrodes considering the mirror displacement and activation voltage. Here we could show that tunable MCs based on oxygen plasma activated PDMS show a homogenous and high thickness decrease up to 70% at 200V.

  14. 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

  15. Sleep quality among elderly high-altitude dwellers in Ladakh.

    PubMed

    Sakamoto, Ryota; Okumiya, Kiyohito; Norboo, Tsering; Tsering, Norboo; Yamaguchi, Takayoshi; Nose, Mitsuhiro; Takeda, Shinya; Tsukihara, Toshihiro; Ishikawa, Motonao; Nakajima, Shun; Wada, Taizo; Fujisawa, Michiko; Imai, Hissei; Ishimoto, Yasuko; Kimura, Yumi; Fukutomi, Eriko; Chen, Wenling; Otsuka, Kuniaki; Matsubayashi, Kozo

    2017-03-01

    It has been already known that people who temporarily stay at high altitude may develop insomnia as a symptom of acute mountain sickness. However, much less is known about people living at high altitude. The aim of this study was to determine the effect of high altitude environment on sleep quality for the elderly who have been living at high altitude for their whole lives. A cross-sectional study was conducted in Domkhar valley at altitudes of 2800-4200m, Ladakh. Sleep quality was assessed using Insomnia Severity Index (ISI). Measurement items include body mass index, blood pressure, blood sugar, hemoglobin, timed Up and Go test, oxygen saturation during wakefulness, respiratory function test, Oxford Knee Score (OKS), and Geriatric Depression Scale (GDS), and so on. The participants were Ladakhi older adults aged 60 years or over (n=112) in Domkhar valley. The participation rate was 65.1% (male: female=47:65, mean age: 71.3 years and 67.9 years, respectively). The prevalence of the high score of ISI (8 or more) was 15.2% (17 out of 112). Altitude of residence was significantly correlated with ISI. Stepwise multiple regression analysis showed that OKS and altitude of residence were significantly related with ISI.

  16. 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

  17. High quality (In)GaN films on homoepitaxial substrates

    NASA Astrophysics Data System (ADS)

    Liu, Li; Zhang, Yong; Yin, Yian

    2017-02-01

    High quality GaN and InGaN epitaxial thin films were deposited by metal organic chemical vapor deposition (MOCVD). Two sets of thin film samples were prepared by varying the substrates and temperatures under a proper condition for achieving better optical properties. The morphological, crystalline quality and optical property of epitaxial layers were characterized by atomic force microscope (AFM), X-ray diffraction (XRD), photoluminescence (PL) and Raman spectra, respectively. It was found that the epitaxial layers grown on GaN homoepitaxial substrate have higher quality than those grown on sapphire substrate. The root mean square (RMS) of GaN film and InGaN film in AFM morphological were 0.5 nm, 2.7 nm respectively. The full width at half maximum (FWHM) of (102) in GaN film on GaN substrate was 33arcsec and the FWHM of (002) in InGaN film on GaN substrate was 50.58arcsec by XRD. The PL peaks of GaN film and InGaN film were 361 nm, 458 nm respectively. The E2 (high) of GaN film and InGaN film in Raman were both 567.08 cm-1.

  18. High quality factor resonance at room temperature with nanostrings under high tensile stress

    NASA Astrophysics Data System (ADS)

    Verbridge, Scott S.; Parpia, Jeevak M.; Reichenbach, Robert B.; Bellan, Leon M.; Craighead, H. G.

    2006-06-01

    Quality factors as high as 207 000 are demonstrated at room temperature for radio-frequency silicon nitride string resonators with cross sectional dimensions on the scale of 100 nm, made with a nonlithographic technique. A product of quality factor and surface to volume ratio greater than 6000 nm-1 is presented, the highest yet reported. Doubly clamped nanostring resonators are fabricated in high tensile-stress silicon nitride using a nonlithographic electrospinning process. We fabricate devices with an electron beam process, and demonstrate frequency and quality factor results identical to those obtained with the nonlithographic technique. We also compare high tensile-stress doubly clamped beams with doubly clamped and cantilever resonators made of a lower stress material, as well as cantilever beams made of the high stress material. In all cases, the doubly clamped high stress beams have the highest quality factors. We therefore attribute the high quality factors to high tensile stress. Potential dominant loss mechanisms are discussed, including surface and clamping losses, and thermoelastic dissipation. Some practical advantages offered by these nanostrings for mass sensing are discussed.

  19. High-Quality Broadband BVRI Photometry of Benchmark Open Clusters

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.

    Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to archival work and shown to be both accurate and precise. The careful use of a regular routine when making photometric observations, along with the monitoring of instrumental systems and the use of various quality control techniques when making observations or performing data reductions, will enhance an observer's ability to produce high-quality photometric measurements. This work contains a condensed review of the history of photometry, along with a brief description of several popular photometric systems that are often utilized in the field of stellar astrophysics. Publications written by Taylor or produced during the early Taylor and Joner collaboration are deemed especially relevant to the current work. A synopsis of seven archival publications is offered, along with a review of notable reports of VRI photometric observations for the nearby Hyades open star cluster. The body of this present work consists of four publications that appeared between the years 2005 and 2008, along with a soon to be submitted manuscript for a fifth publication. Each of these papers deals specifically with high-quality broadband photometry of open clusters with new data being presented for the Hyades, Coma, NGC 752, Praesepe, and M67. It is concluded that the VRI photometry produced during the Taylor and Joner collaborative investigations forms a high-quality data set that has been: (1) stable for

  20. 2020 vision for a high-quality, high-value maternity care system.

    PubMed

    Carter, Martha Cook; Corry, Maureen; Delbanco, Suzanne; Foster, Tina Clark-Samazan; Friedland, Robert; Gabel, Robyn; Gipson, Teresa; Jolivet, R Rima; Main, Elliott; Sakala, Carol; Simkin, Penny; Simpson, Kathleen Rice

    2010-01-01

    A concrete and useful way to create an action plan for improving the quality of maternity care in the United States is to start with a view of the desired result, a common definition and a shared vision for a high-quality, high-value maternity care system. In this paper, we present a long-term vision for the future of maternity care in the United States. We present overarching values and principles and specific attributes of a high-performing maternity care system. We put forth the "2020 Vision for a High-Quality, High-Value Maternity Care System" to serve as a positive starting place for a fruitful collaborative process to develop specific action steps for broad-based maternity care system improvement.

  1. The synthesis of high-quality diamond in combustion flames

    NASA Astrophysics Data System (ADS)

    Hirose, Yoichi; Amanuma, Shuji; Komaki, Kunio

    1990-12-01

    High-quality diamond with good crystallinity has been successfully synthesized on a substrate using an oxy-acetylene combustion flame in the atmosphere. The crystal grains under some conditions have good optical transparency. The deposition rate of transparent diamond depended strongly on substrate temperatures and the O2/C2H2 ratio and averaged ˜30 μm/h. The substrate temperature for the growth of optically transparent crystals was 500-750 °C, which is relatively low compared with other chemical vapor deposition methods. The optical transparency is attributed to the low defect densities in the crystals, as determined by transmission electron microscope, which results from the low substrate temperatures and moderate growth rates. Raman spectroscopy and x-ray diffraction data on the synthesized crystals were comparable with that of natural diamond. The synthesis conditions and corresponding diamond quality as well as emission spectrum analysis of the combustion flame during diamond synthesis are described.

  2. 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.

  3. Designing High Quality Evaluation Systems for High School Teachers: Challenges and Potential Solutions

    ERIC Educational Resources Information Center

    Tyler, John H.

    2011-01-01

    A central part of education reform today is the wide-ranging and unprecedented effort to either revamp existing teacher evaluation systems or develop and implement entirely new systems. High-quality teacher evaluation systems are seen as one lever for improving the teacher workforce and hence the outcomes of students, including high school…

  4. 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…

  5. 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

  6. Video Snapshots: Creating High-Quality Images from Video Clips.

    PubMed

    Sunkavalli, Kalyan; Joshi, Neel; Kang, Sing Bing; Cohen, Michael F; Pfister, Hanspeter

    2012-11-01

    We describe a unified framework for generating a single high-quality still image ("snapshot") from a short video clip. Our system allows the user to specify the desired operations for creating the output image, such as super resolution, noise and blur reduction, and selection of best focus. It also provides a visual summary of activity in the video by incorporating saliency-based objectives in the snapshot formation process. We show examples on a number of different video clips to illustrate the utility and flexibility of our system.

  7. 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.

  8. 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

  9. Edge electrospinning for high throughput production of quality nanofibers

    NASA Astrophysics Data System (ADS)

    Thoppey, N. M.; Bochinski, J. R.; Clarke, L. I.; Gorga, R. E.

    2011-08-01

    A novel, simple geometry for high throughput electrospinning from a bowl edge is presented that utilizes a vessel filled with a polymer solution and a concentric cylindrical collector. Successful fiber formation is presented for two different polymer systems with differing solution viscosity and solvent volatility. The process of jet initiation, resultant fiber morphology and fiber production rate are discussed for this unconfined feed approach. Under high voltage initiation, the jets spontaneously form directly on the fluid surface and rearrange along the circumference of the bowl to provide approximately equal spacing between spinning sites. Nanofibers currently produced from bowl electrospinning are identical in quality to those fabricated by traditional needle electrospinning (TNE) with a demonstrated ~ 40 times increase in the production rate for a single batch of solution due primarily to the presence of many simultaneous jets. In the bowl electrospinning geometry, the electric field pattern and subsequent effective feed rate are very similar to those parameters found under optimized TNE experiments. Consequently, the electrospinning process per jet is directly analogous to that in TNE and thereby results in the same quality of nanofibers.

  10. Drug discovery from Nature: automated high-quality sample preparation

    PubMed Central

    Thiericke, Ralf

    2000-01-01

    Secondary metabolites from plants, animals and microorganisms have been proven to be an outstanding source for new and innovative drugs and show a striking structural diversity that supplements chemically synthesized compounds or libraries in drug discovery programs. Unfortunately, extracts from natural sources are usually complex mixtures of compounds:: often generated in time consuming and for the most part manual processes. As quality and quantity of the provided samples play a pivotal role in the success of high-throughput screening programs this poses serious problems. In order to make samples of natural origin competitive with synthetic compound libraries, we devised a novel, automated sample preparation procedure based on solid-phase extraction (SPE). By making use of a modified Zymark RapidTrace® SPE workstation an easy-to-handle and effective fractionation method has been developed which allows the generation of highquality samples from natural origin, fulfilling the requirements of an integration into high-throughput screening programs. PMID:18924703

  11. 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.

  12. 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.

  13. Model microcavity laser with CdSe/CdS quantum dots as lasing media

    NASA Astrophysics Data System (ADS)

    Naveed, H. B.; Popov, S.; Shafique, M.

    2016-02-01

    A model is established for a microcavity laser with cadmium selenium/cadmium sulfide (CdSe/CdS) core/shell quantum dots (QDs) as a lasing medium. The research was organised to develop and solve the rate equations for the above mentioned microcavity laser to calculate the output parameters during lasing. Using time-resolved fluorescence spectroscopy, the radiative life time of the lasing medium was measured along with its fluorescence and absorption spectra. A model is also established on the basis of the segment contact method (SCM) to demonstrate the threshold gain profile using the absorption spectrum of CdSe/CdS core/shell type-II QDs residing in the cavity. A laser cavity of size 1 μm was pumped with an optical source (532 nm) to achieve an optimised laser peak at 470 nm.

  14. Divergent Petermann factor of interacting resonances in a stadium-shaped microcavity

    NASA Astrophysics Data System (ADS)

    Lee, Soo-Young; Ryu, Jung-Wan; Shim, Jeong-Bo; Lee, Sang-Bum; Kim, Sang Wook; An, Kyungwon

    2008-07-01

    It is numerically shown that the Petermann excess noise factor diverges to infinity at an exceptional point (EP) found near an avoided resonance crossing in a stadium-shaped dielectric microcavity. Square-root singularity of eigenvalue at the EP is explicitly demonstrated in two-dimensional parameter space spanned by refractive index and deformation parameter. The results imply that mode-mode interaction makes the Petermann factor large.

  15. Stable integrated hyper-parametric oscillator based on coupled optical microcavities.

    PubMed

    Armaroli, Andrea; Feron, Patrice; Dumeige, Yannick

    2015-12-01

    We propose a flexible scheme based on three coupled optical microcavities that permits us to achieve stable oscillations in the microwave range, the frequency of which depends only on the cavity coupling rates. We find that the different dynamical regimes (soft and hard excitation) affect the oscillation intensity, but not their periods. This configuration may permit us to implement compact hyper-parametric sources on an integrated optical circuit with interesting applications in communications, sensing, and metrology.

  16. Near-field observation of subwavelength confinement of photoluminescence by a photonic crystal microcavity.

    PubMed

    Louvion, Nicolas; Rahmani, Adel; Seassal, Christian; Callard, Ségolène; Gérard, Davy; de Fornel, Frédérique

    2006-07-15

    We present a direct, room-temperature near-field optical study of light confinement by a subwavelength defect microcavity in a photonic crystal slab containing quantum-well sources. The observations are compared with three-dimensional finite-difference time-domain calculations, and excellent agreement is found. Moreover, we use a subwavelength cavity to study the influence of a near-field probe on the imaging of localized optical modes.

  17. 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.

  18. 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.

  19. Transverse strain response of in-fibre Fabry-Perot microcavities

    NASA Astrophysics Data System (ADS)

    Manders, Mark; Partridge, Matthew; Correia, Ricardo N.; James, Stephen W.; Tatam, Ralph P.

    2014-05-01

    In-fibre microcavity Fabry-Perot interferometers were constructed by splicing single mode fibre to polarisation maintaining photonic crystal fibre (PCF), with the air in the PCF pressurised to 5.000±0.005bar. The response to transverse load was characterised, along with the influence of rotational orientation and the repeatability of the fabrication process. It was found that the features of the channelled reflected spectrum exhibited a blue wavelength shift with increasing applied transverse load.

  20. Blueprint for action: steps toward a high-quality, high-value maternity care system.

    PubMed

    Angood, Peter B; Armstrong, Elizabeth Mitchell; Ashton, Diane; Burstin, Helen; Corry, Maureen P; Delbanco, Suzanne F; Fildes, Barbara; Fox, Daniel M; Gluck, Paul A; Gullo, Sue Leavitt; Howes, Joanne; Jolivet, R Rima; Laube, Douglas W; Lynne, Donna; Main, Elliott; Markus, Anne Rossier; Mayberry, Linda; Mitchell, Lynn V; Ness, Debra L; Nuzum, Rachel; Quinlan, Jeffrey D; Sakala, Carol; Salganicoff, Alina

    2010-01-01

    Childbirth Connection hosted a 90th Anniversary national policy symposium, Transforming Maternity Care: A High Value Proposition, on April 3, 2009, in Washington, DC. Over 100 leaders from across the range of stakeholder perspectives were actively engaged in the symposium work to improve the quality and value of U.S. maternity care through broad system improvement. A multi-disciplinary symposium steering committee guided the strategy from its inception and contributed to every phase of the project. The "Blueprint for Action: Steps Toward a High Quality, High Value Maternity Care System", issued by the Transforming Maternity Care Symposium Steering Committee, answers the fundamental question, "Who needs to do what, to, for, and with whom to improve the quality of maternity care over the next five years?" Five stakeholder workgroups collaborated to propose actionable strategies in 11 critical focus areas for moving expeditiously toward the realization of the long term "2020 Vision for a High Quality, High Value Maternity Care System", also published in this issue. Following the symposium these workgroup reports and recommendations were synthesized into the current blueprint. For each critical focus area, the "Blueprint for Action" presents a brief problem statement, a set of system goals for improvement in that area, and major recommendations with proposed action steps to achieve them. This process created a clear sightline to action that if enacted could improve the structure, process, experiences of care, and outcomes of the maternity care system in ways that when anchored in the culture can indeed transform maternity care.

  1. 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.

  2. Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

    NASA Astrophysics Data System (ADS)

    Heng, Hang; Wang, Rong

    2017-01-01

    Optical metamaterials can concentrate light into extremely tiny volumes to enhance their interaction with quantum objects. In this paper, a cylindrical microcavity based on the Au-dielectric-Au sandwiched structure is proposed. Numerical study shows that the cylindrical microcavity has the strong ability of localizing light and confining 103- 104-fold enhancement of the electromagnetic energy density, which contains the most energy of the incoming light. The enhancement factor of energy density G inside the cavity shows the regularities as the change in the thickness of the dielectric slab, dielectric constant, and the radius of gold disk. At the normal incidence of electromagnetic radiation, the obtained reflection spectra operate in the range from 4.8 μm to 6 μm and with the absorption efficiency C (C=1-R min), which can reach 99% by optimizing the structure's geometry parameters, and the dielectric constant. Due to the symmetry of the cylindrical microcavities, this structure is insensitive to the polarization of the incident wave. The proposed optical metamaterials will have potential applications in the surface enhanced spectroscopy, new plasmonic detectors, bio-sensing, solar cells, etc.

  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. 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.

  5. 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

    2016-09-05

    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.

  6. 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.

  7. 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

  8. 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

    2015-11-10

    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.

  9. Wind resource quality affected by high levels of renewables

    DOE PAGES

    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

  10. 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.

  11. Recruiting and retaining high-quality teachers in rural areas.

    PubMed

    Monk, David H

    2007-01-01

    In examining recruitment and retention of teachers in rural areas, David Monk begins by noting the numerous possible characteristics of rural communities--small size, sparse settlement, distance from population concentrations, and an economic reliance on agricultural industries that are increasingly using seasonal and immigrant workers to minimize labor costs. Many, though not all, rural areas, he says, are seriously impoverished. Classes in rural schools are relatively small, and teachers tend to report satisfaction with their work environments and relatively few problems with discipline. But teacher turnover is often high, and hiring can be difficult. Monk observes that rural schools have a below-average share of highly trained teachers. Compensation in rural schools tends to be low, perhaps because of a lower fiscal capacity in rural areas, thus complicating efforts to attract and retain teachers. Several student characteristics, including relatively large shares of students with special needs and with limited English skills and lower shares of students attending college, can also make it difficult to recruit and retain high-quality teachers. Other challenges include meeting the needs of highly mobile children of low-income migrant farm workers. With respect to public policy, Monk asserts a need to focus on a subcategory of what might be called hard-to-staff rural schools rather than to develop a blanket set of policies for all rural schools. In particular, he recommends a focus on such indicators as low teacher qualifications, teaching in fields far removed from the area of training, difficulty in hiring, high turnover, a lack of diversity among teachers in the school, and the presence of migrant farm workers' children. Successful efforts to stimulate economic growth in these areas would be highly beneficial. He also calls attention to the potential for modern telecommunication and computing technologies to offset some of the drawbacks associated with teaching

  12. 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 ...

  13. 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

  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)

    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.

  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)

    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.

  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. 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.

  19. High power, high beam quality solid state lasers for materials processing applications

    SciTech Connect

    Hackel, L.A.; Dane, C.B.; Hermann, M.R.

    1994-08-01

    The Laser Science and Technology Department at Lawrence Livermore National Laboratory is developing solid state lasers with high average power and high beam quality. Specific systems include a laser to generate 10 to 14 {angstrom} x-rays for proximity print lithography, a 400 mJ, 500 Hz laser for 130 {angstrom} projection lithography and unique systems for speckle imaging, laser radars and medical treatments.

  20. 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…

  1. 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).

  2. Total Quality Management: A Management Philosophy for Providing High Quality Construction

    DTIC Science & Technology

    1992-01-01

    of products and service during the construction process. Under the philosophy of TQM, we build quality into the finished product....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

  3. 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

  4. 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.

  5. High-quality frame-synchronization for satellite video signal transmission

    NASA Astrophysics Data System (ADS)

    Kubota, Shuji; Morikura, Masahiro; Kato, Shuzo

    1995-01-01

    A high-quality frame-synchronizer for video signal switching and freezing is proposed. In order to realize high-quality frame-synchronization, a novel high-speed and high-definition 11 bit analog-to-digital (A/D) converter which achieves the quite high unweighted S/N ratio performance of 63 dB is developed. It provides synchronized video signal switching by field freezing for high-quality video signal transmission.

  6. Image quality and high contrast improvements on VLT/NACO

    NASA Astrophysics Data System (ADS)

    Girard, Julien H. V.; O'Neal, Jared; Mawet, Dimitri; Kasper, Markus; Zins, Gérard; Neichel, Benoît; Kolb, Johann; Christiaens, Valentin; Tourneboeuf, Martin

    2012-07-01

    NACO is the famous and versatile diffraction limited NIR imager and spectrograph at the VLT with which ESO celebrated 10 years of Adaptive Optics. Since two years a substantial effort has been put in understanding and fixing issues that directly affect the image quality and the high contrast performances of the instrument. Experiments to compensate the non-common-path aberrations and recover the highest possible Strehl ratios have been carried out successfully and a plan is hereafter described to perform such measurements regularly. The drift associated to pupil tracking since 2007 was fixed in october 2011. NACO is therefore even more suited for high contrast imaging and can be used with coronagraphic masks in the image plane. Some contrast measurements are shown and discussed. The work accomplished on NACO will serve as reference for the next generation instruments on the VLT, especially the ones working at the diffraction limit and making use of angular differential imaging (i.e. SPHERE, VISIR, and possibly ERIS).

  7. Plasmonic CROWs for Tunable Dispersion and High Quality Cavity Modes

    NASA Astrophysics Data System (ADS)

    Wood, John J.; Lafone, Lucas; Hamm, Joachim M.; Hess, Ortwin; Oulton, Rupert F.

    2015-12-01

    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.

  8. 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.

  9. 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

  10. A Novel Process to Synthesize High-Quality Ferrovanadium Nitride

    NASA Astrophysics Data System (ADS)

    Wu, Yue-Dong; Zhang, Guo-Hua; Chou, Kuo-Chih

    2016-12-01

    In the present work, high-quality ferrovanadium nitride, which has a relative high nitrogen content and a low carbon content, has been prepared by roasting the mixture of vanadium pentoxide, carbon, and ferric oxide under N2 atmosphere in the temperature range from 1673 K to 1873 K (1400 °C to 1600 °C). The effects of carbon addition, reaction temperature, and heat treatment process were discussed. It was found that the carbon addition had a great effect on the nitrogen content and residual carbon, and the optimum carbon content was established to obtain the maximum nitrogen content and low carbon content. The reaction temperature in the range from 1673 K to 1873 K (1400 °C to 1600 °C) has a smaller effect on the final nitrogen content, and it also affects the degree of agglomeration of particles, which were observed by scanning electron microscope. From the results of thermodynamic calculation, energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD), it was deduced that the reaction sequence of V2O5 with N2 from 1673 K to 1873 K (1400 °C to 1600 °C) was V2O5 → VO2 → V2O3 → V(N, C, O) → V(N, C). There is a little solid solubility of carbon in the final product VN.

  11. Effects of harvesting methods on foreign matter content, fiber quality, and yarn quality from irrigated cotton on the high plains.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Harvest treatments were compared for a variety of cotton commonly grown on the High Plains of Texas. Foreign matter, fiber quality, and yarn quality were compared for cotton harvested using a spindle picker, a brush-roll stripper with a field cleaner, and the same stripper harvester without a field ...

  12. Effective W-state fusion strategies for electronic and photonic qubits via the quantum-dot-microcavity coupled system

    PubMed Central

    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

  13. All-optical switching with bacteriorhodopsin protein coated microcavities and its application to low power computing circuits

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Prasad, Mohit; Topolancik, Juraj; Vollmer, Frank

    2010-03-01

    We show all-optical switching of an input infrared laser beam at 1310 nm by controlling the photoinduced retinal isomerization to tune the resonances in a silica microsphere coated with three bacteriorhodopsin (BR) protein monolayers. The all-optical tunable resonant coupler re-routes the infrared beam between two tapered fibers in 50 μs using a low power (<200 μW) green (532 nm) and blue (405 nm) pump beams. The basic switching configuration has been used to design all-optical computing circuits, namely, half and full adder/subtractor, de-multiplexer, multiplexer, and an arithmetic unit. The design requires 2n-1 switches to realize n bit computation. The designs combine the exceptional sensitivities of BR and high-Q microcavities and the versatile tree architecture for realizing low power circuits and networks (approximately mW power budget). The combined advantages of high Q-factor, tunability, compactness, and low power control signals, with the flexibility of cascading switches to form circuits, and reversibility and reconfigurability to realize arithmetic and logic functions, makes the designs promising for practical applications. The designs are general and can be implemented (i) in both fiber-optic and integrated optic formats, (ii) with any other coated photosensitive material, or (iii) any externally controlled microresonator switch.

  14. Photonic transistor and router using a single quantum-dot-confined spin in a single-sided optical microcavity.

    PubMed

    Hu, C Y

    2017-03-28

    The future Internet is very likely the mixture of all-optical Internet with low power consumption and quantum Internet with absolute security guaranteed by the laws of quantum mechanics. Photons would be used for processing, routing and com-munication of data, and photonic transistor using a weak light to control a strong light is the core component as an optical analogue to the electronic transistor that forms the basis of modern electronics. In sharp contrast to previous all-optical tran-sistors which are all based on optical nonlinearities, here I introduce a novel design for a high-gain and high-speed (up to terahertz) photonic transistor and its counterpart in the quantum limit, i.e., single-photon transistor based on a linear optical effect: giant Faraday rotation induced by a single electronic spin in a single-sided optical microcavity. A single-photon or classical optical pulse as the gate sets the spin state via projective measurement and controls the polarization of a strong light to open/block the photonic channel. Due to the duality as quantum gate for quantum information processing and transistor for optical information processing, this versatile spin-cavity quantum transistor provides a solid-state platform ideal for all-optical networks and quantum networks.

  15. Photonic transistor and router using a single quantum-dot-confined spin in a single-sided optical microcavity

    PubMed Central

    Hu, C. Y.

    2017-01-01

    The future Internet is very likely the mixture of all-optical Internet with low power consumption and quantum Internet with absolute security guaranteed by the laws of quantum mechanics. Photons would be used for processing, routing and com-munication of data, and photonic transistor using a weak light to control a strong light is the core component as an optical analogue to the electronic transistor that forms the basis of modern electronics. In sharp contrast to previous all-optical tran-sistors which are all based on optical nonlinearities, here I introduce a novel design for a high-gain and high-speed (up to terahertz) photonic transistor and its counterpart in the quantum limit, i.e., single-photon transistor based on a linear optical effect: giant Faraday rotation induced by a single electronic spin in a single-sided optical microcavity. A single-photon or classical optical pulse as the gate sets the spin state via projective measurement and controls the polarization of a strong light to open/block the photonic channel. Due to the duality as quantum gate for quantum information processing and transistor for optical information processing, this versatile spin-cavity quantum transistor provides a solid-state platform ideal for all-optical networks and quantum networks. PMID:28349960

  16. 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.

  17. High-power 83 W holmium-doped silica fiber laser operating with high beam quality.

    PubMed

    Jackson, Stuart D; Sabella, Alex; Hemming, Alex; Bennetts, Shayne; Lancaster, David G

    2007-02-01

    A high-power 83 W cladding-pumped Tm3+-Ho3+-doped silica fiber laser is reported. Using bidirectional 793 nm diode pumping, a maximum slope efficiency of 42% was produced after a threshold launched pump power of 12 W was exceeded. The laser operated at wavelengths near 2105 nm with moderate beam quality, i.e., M2 approximately 1.5. Further power scaling of the fiber laser was limited by thermal failure of the fiber ends.

  18. High-power 83 W holmium-doped silica fiber laser operating with high beam quality

    NASA Astrophysics Data System (ADS)

    Jackson, Stuart D.; Sabella, Alex; Hemming, Alex; Bennetts, Shayne; Lancaster, David G.

    2007-02-01

    A high-power 83W cladding-pumped Tm3+-Ho3+-doped silica fiber laser is reported. Using bidirectional 793nm diode pumping, a maximum slope efficiency of 42% was produced after a threshold launched pump power of 12W was exceeded. The laser operated at wavelengths near 2105nm with moderate beam quality, i.e., M2˜1.5. Further power scaling of the fiber laser was limited by thermal failure of the fiber ends.

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

    PubMed

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

    2013-03-11

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

  20. 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.

  1. High gain pre-amplifier laser beam quality evaluating system

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Yu, Jin; Zhao, Tianzhuo; Zhang, Xue; Fan, Zhongwei

    2011-06-01

    Designed a system for the high gain laser pre-amplifier to evaluate the image quality. The system uses 4f imaging principle and Kepler type telescope was choiced, it has two advantages: avert optical distortion and eliminate aberration in the measurement system. Combined with the location of the lens inside of pre-amplifier such as the spatial filter , the near field imaging structure was designed. The structure can be reduced to 11.9 times the beam image, and clearly passed the image to the CCD target surface. The location of first positive lens focus is the location of far field image. In this article, one laser pre-amplifier was measured. The average measured near field modulation M=1.34, the average measured far field diffraction limit is 2.94. Experiments show that the stability of measuring system is less than+/-5%, it can meet the measurement requirements of ICF laser pre-amplifier parameters. Use this system we can discover the problem during the design and installation. There is great meaning for develop of laser pre-amplifier in ICF for further.

  2. High quality factor platinum silicide microwave kinetic inductance detectors

    NASA Astrophysics Data System (ADS)

    Szypryt, P.; Mazin, B. A.; Ulbricht, G.; Bumble, B.; Meeker, S. R.; Bockstiegel, C.; Walter, A. B.

    2016-10-01

    We report on the development of microwave kinetic inductance detectors (MKIDs) using platinum silicide as the sensor material. MKIDs are an emerging superconducting detector technology, capable of measuring the arrival times of single photons to better than two microseconds and their energies to around ten percent. Previously, MKIDs have been fabricated using either sub-stoichiometric titanium nitride or aluminum, but TiN suffers from the spatial inhomogeneities in the superconducting critical temperature and Al has a low kinetic inductance fraction, causing low detector sensitivity. To address these issues, we have instead fabricated the PtSi microresonators with the superconducting critical temperatures of 944 ± 12 mK and high internal quality factors ( Q i ≳ 10 6 ). These devices show typical quasiparticle lifetimes of τ q p ≈ 30 - 40 μ s and spectral resolution, R = λ / Δ λ , of 8 at 406.6 nm. We compare PtSi MKIDs to those fabricated with TiN and detail the substantial advantages that PtSi MKIDs have to offer.

  3. 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

  4. 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…

  5. 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.

  6. 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.

  7. High power far-infrared optical parametric oscillator with high beam quality

    NASA Astrophysics Data System (ADS)

    Qian, Chuan-Peng; Shen, Ying-Jie; Dai, Tong-Yu; Duan, Xiao-Ming; Yao, Bao-Quan

    2016-11-01

    A high power ZnGeP2 (ZGP) optical parametric oscillator (OPO) with good beam quality pumped by a Q-switched Ho:YAG laser was demonstrated. The maximum output power of the ZGP OPO with a four-mirror ring cavity was about 5.04 W around 8.1 μm with 83.9 W Ho incident pump power, corresponding to a slope efficiency of 9.2 %. The ZGP OPO produced 36.0 ns far-IR pulse laser in the 8.0-8.3 μm spectral regions. The beam quality was measured to be M2 1.6 at the highest output power.

  8. Quality improvement in healthcare in New Zealand. Part 1: what would a high-quality healthcare system look like?

    PubMed

    Seddon, Mary

    2006-07-07

    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.

  9. Circularly polarized lasing in chiral modulated semiconductor microcavity with GaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Demenev, A. A.; Kulakovskii, V. D.; Schneider, C.; Brodbeck, S.; Kamp, M.; Höfling, S.; Lobanov, S. V.; Weiss, T.; Gippius, N. A.; Tikhodeev, S. G.

    2016-10-01

    We report close to circularly polarized lasing at ℏ ω = 1.473 and 1.522 eV from an AlAs/AlGaAs Bragg microcavity, with 12 GaAs quantum wells in the active region and chirally etched upper distributed Bragg refractor under optical pump at room temperature. The advantage of using the chiral photonic crystal with a large contrast of dielectric permittivities is its giant optical activity, allowing to fabricate a very thin half-wave plate, with a thickness of the order of the emitted light wavelength, and to realize the monolithic control of circular polarization.

  10. Generation of ultrashort pulses via self-pulsations in coupled nonlinear microcavities

    NASA Astrophysics Data System (ADS)

    Grigoriev, Victor; Biancalana, Fabio

    2010-10-01

    The energy exchange between coupled microcavities is shown to counteract the switching process, giving rise to self-pulsations. A nonlinear photonic crystal with two artificially placed defects is proposed as a representative example of such system. The coupled-mode equations are applied to describe its dynamical properties and to analyze the stability of solutions obtained by the transfer matrix method. Here we show how to control the parameters of the system in order to design a device that converts continuous waves into very regular and ultrashort pulses.

  11. Static envelope patterns in composite resonances generated by level crossing in optical toroidal microcavities.

    PubMed

    Carmon, Tal; Schwefel, Harald G L; Yang, Lan; Oxborrow, Mark; Stone, A Douglas; Vahala, Kerry J

    2008-03-14

    We study level crossing in the optical whispering-gallery (WG) modes by using toroidal microcavities. Experimentally, we image the stationary envelope patterns of the composite optical modes that arise when WG modes of different wavelengths coincide in frequency. Numerically, we calculate crossings of levels that correspond with the observed degenerate modes, where our method takes into account the not perfectly transverse nature of their field polarizations. In addition, we analyze anticrossing with a large avoidance gap between modes of the same azimuthal number.

  12. Power dependence on the nonlinear interaction enhancement in a coherently excited microcavity

    NASA Astrophysics Data System (ADS)

    Serna, Samuel; Hanna, Marc; Le-Roux, Xavier; Delaye, Philippe; Cassan, Eric; Dubreuil, Nicolas

    2016-11-01

    The enhanced nonlinear interaction in a silicon microcavity under coherent excitation is studied under different conditions. By controlling the pulse frequency drift, we guarantee, at every instant, the coincidence with the frequency resonance of the cavity that in the nonlinear regime suffers from a blue shift in time. This limiting shift effect is caused by the free carriers generated by the strong silicon two-photon absorption. Owing to the linear time-frequency relation of the pulse, the coupling efficiency to the drifted resonance can be maintained, further increasing the blue-shift. We study the input power effect after using different pulse durations.

  13. Design and analysis of an electrically pumped microcavity organic laser device

    NASA Astrophysics Data System (ADS)

    Shayesteh, Mohammad Reza

    2017-02-01

    We propose a new structure of organic vertical-cavity surface-emitting laser to be pumped electrically. The microcavity structure consists of an organic light emitting diode with field-effect electron transport set in between multilayer dielectric mirrors. The threshold behavior and the dynamics of the proposed OVCSEL are analyzed numerically. We show that the device can reach the lasing threshold under electrical pump at a current density of 24 A/cm2. Also, the dynamic behavior of the device under pulsed excitation is investigated. The results show that pulse excitation reduces field quenching and triplet exciton losses; hence, output photon density can be increased. [Figure not available: see fulltext.

  14. 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

  15. Emission polarization control in semiconductor quantum dots coupled to a photonic crystal microcavity.

    PubMed

    Gallardo, E; Martínez, L J; Nowak, A K; van der Meulen, H P; Calleja, J M; Tejedor, C; Prieto, I; Granados, D; Taboada, A G; García, J M; Postigo, P A

    2010-06-07

    We study the optical emission of single semiconductor quantum dots weakly coupled to a photonic-crystal micro-cavity. The linearly polarized emission of a selected quantum dot changes continuously its polarization angle, from nearly perpendicular to the cavity mode polarization at large detuning, to parallel at zero detuning, and reversing sign for negative detuning. The linear polarization rotation is qualitatively interpreted in terms of the detuning dependent mixing of the quantum dot and cavity states. The present result is relevant to achieve continuous control of the linear polarization in single photon emitters.

  16. 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.

  17. High throughput electrospinning of high-quality nanofibers via an aluminum disk spinneret

    NASA Astrophysics Data System (ADS)

    Zheng, Guokuo

    In this work, a simple and efficient needleless high throughput electrospinning process using an aluminum disk spinneret with 24 holes is described. Electrospun mats produced by this setup consisted of fine fibers (nano-sized) of the highest quality while the productivity (yield) was many times that obtained from conventional single-needle electrospinning. The goal was to produce scaled-up amounts of the same or better quality nanofibers under variable concentration, voltage, and the working distance than those produced with the single needle lab setting. The fiber mats produced were either polymer or ceramic (such as molybdenum trioxide nanofibers). Through experimentation the optimum process conditions were defined to be: 24 kilovolt, a distance to collector of 15cm. More diluted solutions resulted in smaller diameter fibers. Comparing the morphologies of the nanofibers of MoO3 produced by both the traditional and the high throughput set up it was found that they were very similar. Moreover, the nanofibers production rate is nearly 10 times than that of traditional needle electrospinning. Thus, the high throughput process has the potential to become an industrial nanomanufacturing process and the materials processed by it may be used as filtration devices, in tissue engineering, and as sensors.

  18. 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.…

  19. 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....

  20. 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…

  1. 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

  2. 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…

  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. High-Impact Afterschool for All: A Statewide Quality Framework

    ERIC Educational Resources Information Center

    Siaca, Jennifer L.

    2010-01-01

    The need for afterschool programs is clear: Research and practice demonstrate that quality afterschool programs keep youth safe; support working families; and provide critical learning, personal development, arts, and recreational opportunities. New York State alone uses nearly $300 million in local, state, and federal funds for afterschool…

  5. Evanescent field excitation of Cy5-conjugated lipid bilayers using optical microcavities

    NASA Astrophysics Data System (ADS)

    Freeman, Lindsay M.; Dayani, Yasaman; Li, Su; Choi, Hong-Seok; Malmstadt, Noah; Armani, Andrea M.

    2011-09-01

    Whispering gallery mode optical microresonators are devices used for performing ultra-sensitive optical detection. Although the majority of the sensor research has been focused on label-free detection strategies for diagnostics, a whispering gallery mode device is ideally suited to perform fluorescent label-based biodetection as well. However, previous research using optical microcavities to excite fluorescent molecules has focused on cavity quantum electrodynamics applications and fundamental studies of the interactions of large fluorescent nanoparticles with the resonant cavity. In the present work, a method for forming self-assembled lipid bilayers, a mimic for cell membranes, on a spherical microresonator is developed. Solid-supported lipid bilayers, which are approximately 5nm thick, have been shown to accurately model cell membranes, and researchers use lipid bilayers in combination with fluorescent microscopy when developing theoretical models for the transport of molecules across the cell membrane. The bilayernature is verified using both fluorescent resonance energy transfer and fluorescence recovery after photobleaching. The evanescent tail of the microresonator is used to excite a Cy5-conjugated lipid located within the bilayer while the underlying optical device behavior is characterized at 633nm and 980nm. The emission wavelength of the Cy5 dye and the optical performance (Q factor) of the microcavity agree with theoretical predictions.

  6. To the theory of hybrid organics/semiconductor nanostructures in microcavity

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    We consider the hybrid structure in microcavity where the energy of Frenkel exciton in organic layer is equal to the energy of Wannier - Mott exciton in semiconductor quantum well (QW). The exciton located in QW of semiconductor layer can interact with molecules of organic layer and under influence of this interaction can change the position jumping and exciting one of organic molecules. The exciton located in molecule of organic layer also can change the position jumping to semiconductor QW. The number of such jumps depends on the intensity of interaction. In the paper we consider the influence of direct Coulomb dipole-dipole interaction and indirect interaction through the optical field of microcavity on the kinetics of excitation. It was shown that the dispersion of hybrid states are modified by Coulomb interaction particularly when the distance between layers is enough small. The lowest branch of dispersion curves with deep minimum at nonzero wave vector may be useful in the studies of the condensation of low energy hybrid excitations.

  7. Numerical Prediction of the Hypersonic Boundary-Layer Over a Row of Microcavities

    NASA Astrophysics Data System (ADS)

    Theofilis, Vassilios

    2002-09-01

    This report results from tasking Nu-Modeling, Inc. as follows: the contractor will perform detailed numerical predictions of the flowfield in the neighborhood of the microcavities that are embedded in wall-coatings. The key deliverable of the proposed work will be the ability to put forward an improved integral condition to replace what is used in the current theoretical approach. This will be determined numerically at each of the parameters of the problem. The numerical effort required for the solution of the problem at a single value of each of the parameters involved limits to subset of the (M, Re, m, d, d/D, d/ s) parameter space that can be investigated within the available year. It is intended to approximate existing analytic results of Fedorov first, at a single set of parameters, by imposing his pressure boundary condition at the lips of the microcavities (i.e. taking D=0). The effect of nonzero values of this parameter will then be examined, keeping all other parameters in the problem constant. Subsequently, the effect of d, and 5 will be investigated, at constant D and 2(d+s). In all D1 0 cases to be studied, integral boundary conditions will be provided to the parties involved in the project. Progress of the proposed research will be monitored by means of one intermediate and one final report.

  8. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons.

    PubMed

    Rahman, Sk Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-10-04

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires.

  9. 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.

  10. Tapered optical fiber tip probes based on focused ion beam-milled Fabry-Perot microcavities

    NASA Astrophysics Data System (ADS)

    André, Ricardo M.; Warren-Smith, Stephen C.; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M. I.; Latifi, H.; Marques, Manuel B.; Bartelt, Hartmut; Frazão, Orlando

    2016-09-01

    Focused ion beam technology is combined with dynamic chemical etching to create microcavities in tapered optical fiber tips, resulting in fiber probes for temperature and refractive index sensing. Dynamic chemical etching uses hydrofluoric acid and a syringe pump to etch standard optical fibers into cone structures called tapered fiber tips where the length, shape, and cone angle can be precisely controlled. On these tips, focused ion beam is used to mill several different types of Fabry-Perot microcavities. Two main cavity types are initially compared and then combined to form a third, complex cavity structure. In the first case, a gap is milled on the tapered fiber tip which allows the external medium to penetrate the light guiding region and thus presents sensitivity to external refractive index changes. In the second, two slots that function as mirrors are milled on the tip creating a silica cavity that is only sensitive to temperature changes. Finally, both cavities are combined on a single tapered fiber tip, resulting in a multi-cavity structure capable of discriminating between temperature and refractive index variations. This dual characterization is performed with the aid of a fast Fourier transform method to separate the contributions of each cavity and thus of temperature and refractive index. Ultimately, a tapered optical fiber tip probe with sub-standard dimensions containing a multi-cavity structure is projected, fabricated, characterized and applied as a sensing element for simultaneous temperature and refractive index discrimination.

  11. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

    PubMed Central

    Rahman, SK. Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-01-01

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires. PMID:27698359

  12. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

    NASA Astrophysics Data System (ADS)

    Rahman, Sk. Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-10-01

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires.

  13. 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.

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

    PubMed

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

    2014-10-15

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

  15. 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…

  16. 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

  17. 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…

  18. High quality Imaging for space VLBI observations with ultra high angular resolution

    NASA Astrophysics Data System (ADS)

    Likhachev, S.

    2001-01-01

    The focus of this presentation will be the problems associated with obtaining high quality images from a high orbiting space VLBI (SVLBI) mission. SVLBI intensifies and magnifies all imaging problems, making these problems clearer to understand, though much harder to solve. It is necessary to notice that as an astronomical instrument SVLBI possesses one explicit advantage: it is an extremely high angular resolution. Currently it could be up to microarcseconds and unlimited potentially in prospect. At the same time we have to "pay" for this advantage by a few disadvantages making high orbiting SVLBI mission hard to implement. These disadvantages are the following: phase instability, poor (u,v)-coverage, low sensitivity. Possible ways of the solution the problems above were considered. These ways could be the following: usage of Multi-Frequency Synthesis (MFS) enable us to improve poor (u,v)-coverage, dynamic range, and phase instability; usage of sensitive radio telescopes or compact arrays as ground support of the SVLBI mission enable us to improve a sensitivity of the SVLBI mission; usage of two or more space-borne radio telescopes enable us to improve poor (u,v)-coverage and sensitivity; developing a modern imaging technology.

  19. Watt-class high-power, high-beam-quality photonic-crystal lasers

    NASA Astrophysics Data System (ADS)

    Hirose, Kazuyoshi; Liang, Yong; Kurosaka, Yoshitaka; Watanabe, Akiyoshi; Sugiyama, Takahiro; Noda, Susumu

    2014-05-01

    The applications of surface-emitting lasers, in particular vertical-cavity surface-emitting lasers (VCSELs), are currently being extended to various low-power fields including communications and interconnections. However, the fundamental difficulties in increasing their output power by more than several milliwatts while maintaining single-mode operation prevent their application in high-power fields such as material processing, laser medicine and nonlinear optics, despite their advantageous properties of circular beams, the absence of catastrophic optical damage, and their suitability for two-dimensional integration. Here, we demonstrate watt-class high-power, single-mode operation by a two-dimensional photonic-crystal surface-emitting laser under room-temperature, continuous-wave conditions. The two-dimensional band-edge resonant effect of a photonic crystal formed by metal-organic chemical vapour deposition enables a 1,000 times broader coherent-oscillation area, which results in a high beam quality of M2 <= 1.1, narrowing the focus spot by two orders of magnitude compared to VCSELs. Our demonstration promises to realize innovative high-power applications for surface-emitting lasers.

  20. High-resolution multigrating spectrometer for high-quality deep-UV light source production

    NASA Astrophysics Data System (ADS)

    Suzuki, Toru; Kubo, Hirokazu; Suganuma, Takashi; Yamashita, Toshio; Wakabayashi, Osamu; Mizoguchi, Hakaru

    2001-09-01

    Deep UV lithography using ArF excimer laser requires very narrower spectral properties. However, spectrometers that have sufficient resolution to evaluate the ArF excimer laser are commercially not available. High-resolution multi-grating spectrometers for measuring spectral bandwidth at full width at half maximum (FWHM) and spectral purity of ArF excimer lasers are introduced. To achieve high resolution, a special grating arrangement called HEXA (Holographic and Echelle Gratings Expander Arrangement) is designed. A holographic grating and an echelle grating are used so that the input light is expanded and diffracted several times. The resolution of the HEXA spectrometer is more than two million. To evaluate the resolution and the stability of the spectrometer, we measured the instrument function by a coherent light source whose wavelength is same as ArF excimer laser. The experimentally obtained resolution of the spectrometer is 0.09pm or 0.05pm that is selectable. The measured dispersion has a good agreement with the theoretical value. To evaluate the spectral properties of excimer lasers, the instrument function must be very stable. This high-resolution spectrometer enables high quality control of line-narrowed ArF excimer laser mass production.

  1. Implementing 15 Essential Elements for High Quality: A State and Local Policy Scan

    ERIC Educational Resources Information Center

    Barnett, W. Steven; Weisenfeld, G. G.; Brown, Kirsty; Squires, Jim; Horowitz, Michelle

    2016-01-01

    This report explores the extent to which states (and several large cities) are positioned to provide high quality preschool education on a large scale. States and cities that are already doing so or that could do so with modest improvements offer opportunities for advocacy to advance access to high quality early education as well as for rigorous…

  2. 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.

  3. 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…

  4. 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…

  5. 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…

  6. 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%.

  7. Local extinction of dragonfly and damselfly populations in low- and high-quality habitat patches.

    PubMed

    Suhonen, Jukka; Hilli-Lukkarinen, Milla; Korkeamäki, Esa; Kuitunen, Markku; Kullas, Johanna; Penttinen, Jouni; Salmela, Jukka

    2010-08-01

    Understanding the risk of extinction of a single population is an important problem in both theoretical and applied ecology. Local extinction risk depends on several factors, including population size, demographic or environmental stochasticity, natural catastrophe, or the loss of genetic diversity. The probability of local extinction may also be higher in low-quality sink habitats than in high-quality source habitats. We tested this hypothesis by comparing local extinction rates of 15 species of Odonata (dragonflies and damselflies) between 1930-1975 and 1995-2003 in central Finland. Local extinction rates were higher in low-quality than in high-quality habitats. Nevertheless, for the three most common species there were no differences in extinction rates between low- and high-quality habitats. Our results suggest that a good understanding of habitat quality is crucial for the conservation of species in heterogeneous landscapes.

  8. 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

  9. Results with a micro-cavity plasma panel detector

    SciTech Connect

    2015-07-01

    During the three last years, a complete study of a radiation detector based on plasma panel technology (main component of plasma television display) has been completed using source, cosmic ray and beam. This studies showed a fast response (O(5 ns)), high spatial resolution detection of ionizing particle and minimum ionizing particles. It shows very promising results in term of pixel-to-pixel uniformity and time stability of both signal shapes and rates. The prototype has also demonstrated very low background over a wide range of applied high voltages, excellent pixel response isolation, time resolutions of a few nanoseconds, and efficiencies above 95% over a 100-volt range for beta particles emitted by a {sup 106}Ru radioactive source. A full report will be presented (authors)

  10. High performance photodetectors based on high quality InP nanowires

    NASA Astrophysics Data System (ADS)

    Yang, Yan-Kun; Yang, Tie-Feng; Li, Hong-Lai; Qi, Zhao-Yang; Chen, Xin-Liang; Wu, Wen-Qiang; Hu, Xue-Lu; He, Peng-Bin; Jiang, Ying; Hu, Wei; Zhang, Qing-Lin; Zhuang, Xiu-Juan; Zhu, Xiao-Li; Pan, An-Lian

    2016-11-01

    In this paper, small diameter InP nanowires with high crystal quality were synthesized through a chemical vapor deposition method. Benefitting from the high crystallinity and large specific surface area of InP nanowires, the simply constructed photodetector demonstrates a high responsivity of up to 1170 A·W-1 and an external quantum efficiency of 2.8×105% with a fast rise time of 110 ms and a fall time of 130 ms, even at low bias of 0.1 V. The effect of back-gate voltage on photoresponse of the device was systematically investigated, confirming that the photocurrent dominates over thermionic and tunneling currents in the whole operation. A mechanism based on energy band theory at the junction between metal and semiconductor was proposed to explain the back-gate voltage dependent performance of the photodetectors. These convincing results indicate that fine InP nanowires will have a brilliant future in smart optoelectronics. Project supported by the National Natural Science Foundation of China (Grant Nos. 51525202, 61574054, 61505051, and 61474040), the Science and Technology Plan of Hunan Province, China (Grant Nos. 2014FJ2001 and 2014TT1004), and the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, China.

  11. 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.

  12. 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.

  13. Diode Pumped Alkali Vapor Lasers - A New Pathway to High Beam Quality at High Average Power

    SciTech Connect

    Page, R H; Boley, C D; Rubenchik, A M; Beach, R J

    2005-05-06

    Resonance-transition alkali-vapor lasers have only recently been demonstrated [1] but are already attracting considerable attention. Alkali-atom-vapor gain media are among the simplest possible systems known, so there is much laboratory data upon which to base performance predictions. Therefore, accurate modeling is possible, as shown by the zero- free-parameter fits [2] to experimental data on alkali-vapor lasers pumped with Ti:sapphire lasers. The practical advantages of two of the alkali systems--Rb and Cs--are enormous, since they are amenable to diode-pumping [3,4]. Even without circulating the gas mixture, these lasers can have adequate cooling built-in owing to the presence of He in their vapor cells. The high predicted (up to 70%) optical-to-optical efficiency of the alkali laser, the superb (potentially 70% or better) wall-plug efficiency of the diode pumps, and the ability to exhaust heat at high temperature (100 C) combine to give a power-scalable architecture that is lightweight. A recent design exercise [5] at LLNL estimated that the system ''weight-to-power ratio'' figure of merit could be on the order of 7 kg/kW, an unprecedented value for a laser of the 100 kW class. Beam quality is expected to be excellent, owing to the small dn/dT value of the gain medium. There is obviously a long way to go, to get from a small laser pumped with a Ti:sapphire or injection-seeded diode system (of near-perfect beam quality, and narrow linewidth) [1, 4] to a large system pumped with broadband, multimode diode- laser arrays. We have a vision for this technology-development program, and have already built diode-array-pumped Rb lasers at the 1 Watt level. A setup for demonstrating Diode-array-Pumped Alkali vapor Lasers (DPALs) is shown in Figure 1. In general, use of a highly-multimode, broadband pump source renders diode-array-based experiments much more difficult than the previous ones done with Ti:sapphire pumping. High-NA optics, short focal distances, and short

  14. Assembling Ordered Nanorod Superstructures and Their Application as Microcavity Lasers

    PubMed Central

    Liu, Pai; Singh, Shalini; Guo, Yina; Wang, Jian-Jun; Xu, Hongxing; Silien, Christophe; Liu, Ning; Ryan, Kevin M.

    2017-01-01

    Herein we report the formation of multi-layered arrays of vertically aligned and close packed semiconductor nanorods in perfect registry at a substrate using electric field assisted assembly. The collective properties of these CdSexS1-x nanorod emitters are harnessed by demonstrating a relatively low amplified spontaneous emission (ASE) threshold and a high net optical gain at medium pump intensity. The importance of order in the system is highlighted where a lower ASE threshold is observed compared to disordered samples. PMID:28272427

  15. Assembling Ordered Nanorod Superstructures and Their Application as Microcavity Lasers

    NASA Astrophysics Data System (ADS)

    Liu, Pai; Singh, Shalini; Guo, Yina; Wang, Jian-Jun; Xu, Hongxing; Silien, Christophe; Liu, Ning; Ryan, Kevin M.

    2017-03-01

    Herein we report the formation of multi-layered arrays of vertically aligned and close packed semiconductor nanorods in perfect registry at a substrate using electric field assisted assembly. The collective properties of these CdSexS1-x nanorod emitters are harnessed by demonstrating a relatively low amplified spontaneous emission (ASE) threshold and a high net optical gain at medium pump intensity. The importance of order in the system is highlighted where a lower ASE threshold is observed compared to disordered samples.

  16. Surface structures of high-quality diamond crystals synthesized by the oxy-acetylene flame method

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Keiji; Amanuma, Shuji; Hirose, Yoichi

    1992-02-01

    The microstructures of the {111} surfaces of high-quality diamond crystals deposited by the oxy-acetylene flame method have been studied using a high-resolution scanning electron microscope to clear the mechanism of the crystal growth. On the {111} surfaces of the high-quality diamond crystals, the two-dimensional nucleation rate is suppressed and the two-dimensional crystal growth rate is promoted. The suppression of the two-dimensional nucleation rate and the promotion of the two-dimensional crystal growth rate reduce the number of faults, dislocations, and defects and result in the formation of high-quality diamond crystals.

  17. 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…

  18. High-Quality Preschool Programs Found to Improve Adult Status.

    ERIC Educational Resources Information Center

    Weikart, David

    1996-01-01

    The longitudinal High Scope/Perry Preschool Study of 123 African Americans in poverty and at high risk of school failure interviewed 95% of participants at age 27. Profiles indicate that participants had fewer criminal arrests, higher earnings and property wealth, and greater commitment to marriage than nonparticipants, suggesting significant…

  19. 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.

  20. Anomalous Behavior of High Quality Factor Planar Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Megrant, Anthony; Chen, Zijun; Chiaro, Ben; Dunsworth, Andrew; Quintana, Chris; Campbell, Brooks; Kelly, Julian; Barends, Rami; Chen, Yu; Jeffrey, Evan; Mutus, Josh; Neill, Charles; O'Malley, Peter; Sank, Daniel; Vainsencher, Amit; Wenner, Jim; White, Ted; Bochmann, Jorg; Hoi, Iochun; Palmstrom, Christopher; Martinis, John; Cleland, Andrew

    2014-03-01

    Superconducting coplanar waveguide resonators have proven to be invaluable tools in studying some of the decoherence mechanisms found in superconducting qubits. Surface two-level states tend to dominate decoherence at temperatures below Tc/10 and at very low microwave powers, assuming loss through other channels (e.g. quasiparticles, vortices, and radiation loss) has been mitigated through proper shielding and design. I will present recent measurements of resonators whose behavior diverges significantly from the standard two-level state model at low temperatures and low excitation energies, resulting in startling behavior of the internal quality factor. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), through the Army Research Office grant W911NF-09-1-0375.

  1. High cortisol levels are associated with low quality food choice in type 2 diabetes.

    PubMed

    Duong, Michelle; Cohen, Jessica I; Convit, Antonio

    2012-02-01

    Hypothalamic-pituitary-adrenal (HPA) axis control may be impaired in type 2 diabetes (T2DM). Glucocorticoids increase consumption of low quality foods high in calories, sugar, and fat. We explored the relationship between cortisol levels, poor blood glucose control, and food quality choice in T2DM. Twenty-seven healthy controls were age-, gender- and education-matched to 27 T2DM participants. Standard clinical blood tests and cortisol values were measured from fasting blood samples. Participants recorded all consumed food and drink items in a consecutive 3-day food diary. Diaries were analyzed for "high quality" and "low quality" foods using a standardized method with high reliability (0.97 and 0.86, respectively). Controlling for education, body mass index (BMI) and hemoglobin A1C (HbA1C), log-transformed cortisol (LogC) predicted the percent of low quality foods (R (2) = 0.092, β = 0.360, P < 0.05), but not the percent of high quality foods chosen. Controlling for education, BMI, and LogC, HbA1C significantly predicted both the percent of low quality foods (ΔR (2) = 0.079, β = 0.348, P = 0.024) and high quality foods chosen (ΔR (2) = 0.085, β = -0.362, P = 0.022). The relationship between HbA1C and low quality food choice may be mediated by cortisol, controlling for BMI and education (P < 0.01). HbA1C displayed both an indirect (cortisol-mediated) effect (P < 0.05) and direct effect on low quality food choice (P < 0.05). The relationship between HbA1C and low quality food choice may be partially mediated by cortisol. Poor blood glucose control may cause HPA axis disruption, increased consumption of low quality foods.

  2. Submicron Positioning of Single Atoms in a Microcavity

    SciTech Connect

    Nussmann, Stefan; Hijlkema, Markus; Weber, Bernhard; Rohde, Felix; Rempe, Gerhard; Kuhn, Axel

    2005-10-21

    The coupling of individual atoms to a high-finesse optical cavity is precisely controlled and adjusted using a standing-wave dipole-force trap, a challenge for strong atom-cavity coupling. Ultracold Rubidium atoms are first loaded into potential minima of the dipole trap in the center of the cavity. Then we use the trap as a conveyor belt that we set into motion perpendicular to the cavity axis. This allows us to repetitively move atoms out of and back into the cavity mode with a repositioning precision of 135 nm. This makes it possible to either selectively address one atom of a string of atoms by the cavity, or to simultaneously couple two precisely separated atoms to a higher mode of the cavity.

  3. Quality control for bone quality parameters affected by subject motion in high-resolution peripheral quantitative computed tomography.

    PubMed

    Pauchard, Yves; Liphardt, Anna-Maria; Macdonald, Heather M; Hanley, David A; Boyd, Steven K

    2012-06-01

    Subject motion during high-resolution peripheral quantitative computed tomography (HR-pQCT) causes image artifacts that affect morphological analysis of bone quality. The aim of our study was to determine effectiveness of techniques for quality control in the presence of motion in vivo including automated and manual approaches. First, repeatability of manual grading was determined within and between laboratories. Given proper training using a standardized scale and training images (provided by the manufacturer), we found that manual grading is suitable for repeatable image quality grading within and across sites (ICC>0.7). Both a new automated technique providing motion measures based on projection moments, and traditional manual grading (1=best, 5=worst) were subsequently used to assess subject data for motion in N=137 image pairs (scan/re-scan) from the Canadian Multicentre Osteoporosis Study (CaMos) Calgary cohort. High quality image pairs were selected and measurement precision was estimated by calculating the coefficient of variation (CV). Consistent with previous data, density parameters (e.g. total bone mineral density) are more robust than structural (e.g. trabecular number) or finite element parameters (e.g. failure load). To obtain acceptable measurement precision, images should not exceed a manual grading of 3 (on a scale from 1 to 5) or an automatic (ε(T)) grading of 1.2. Automatic and manual grading provide comparable quality control, but the advantage of the automated technique is its ability to provide a motion value at scan time (providing a basis for real time decision regarding re-scan requirements), and the assessment is objective. Notably, automatic motion measurement can be performed retrospectively based on original scan data, and is therefore well suited for multi-center studies as well as any research where objective quality control is paramount.

  4. Transient cavitation in high-quality-factor resonators at high static pressures.

    PubMed

    Gaitan, D Felipe; Tessien, Ross A; Hiller, Robert A; Gutierrez, Joel; Scott, Corey; Tardif, Henry; Callahan, Brant; Matula, Thomas J; Crum, Lawrence A; Holt, R Glynn; Church, Charles C; Raymond, Jason L

    2010-06-01

    It is well known that cavitation collapse can generate intense concentrations of mechanical energy, sufficient to erode even the hardest metals and to generate light emissions visible to the naked eye [sonoluminescence (SL)]. Considerable attention has been devoted to the phenomenon of "single bubble sonoluminescence" (SBSL) in which a single stable cavitation bubble radiates light flashes each and every acoustic cycle. Most of these studies involve acoustic resonators in which the ambient pressure is near 0.1 MPa (1 bar), and with acoustic driving pressures on the order of 0.1 MPa. This study describes a high-quality factor, spherical resonator capable of achieving acoustic cavitation at ambient pressures in excess of 30 MPa (300 bars). This system generates bursts of violent inertial cavitation events lasting only a few milliseconds (hundreds of acoustic cycles), in contrast with the repetitive cavitation events (lasting several minutes) observed in SBSL; accordingly, these events are described as "inertial transient cavitation." Cavitation observed in this high pressure resonator is characterized by flashes of light with intensities up to 1000 times brighter than SBSL flashes, as well as spherical shock waves with amplitudes exceeding 30 MPa at the resonator wall. Both SL and shock amplitudes increase with static pressure.

  5. Cost-effective multi-camera array for high quality video with very high dynamic range

    NASA Astrophysics Data System (ADS)

    Keinert, Joachim; Wetzel, Marcus; Schöberl, Michael; Schäfer, Peter; Zilly, Frederik; Bätz, Michel; Fößel, Siegfried; Kaup, André

    2014-03-01

    Temporal bracketing can create images with higher dynamic range than the underlying sensor. Unfortunately, moving objects cause disturbing artifacts. Moreover, the combination with high frame rates is almost unachiev­ able since a single video frame requires multiple sensor readouts. The combination of multiple synchronized side-by-side cameras equipped with different attenuation filters promises a remedy, since all exposures can be performed at the same time with the same duration using the playout video frame rate. However, a disparity correction is needed to compensate the spatial displacement of the cameras. Unfortunately, the requirements for a high quality disparity correction contradict the goal to increase dynamic range. When using two cameras, disparity correction needs objects to be properly exposed in both cameras. In contrast, a dynamic range in­crease needs the cameras to capture different luminance ranges. As this contradiction has not been addressed in literature so far, this paper proposes a novel solution based on a three camera setup. It enables accurate de­ termination of the disparities and an increase of the dynamic range by nearly a factor of two while still limiting costs. Compared to a two camera solution, the mean opinion score (MOS) is improved by 13.47 units in average for the Middleburry images.

  6. Strong coupling and stimulated emission in single parabolic quantum well microcavity for terahertz cascade

    SciTech Connect

    Tzimis, A.; Savvidis, P. G.; Trifonov, A. V.; Ignatiev, I. V.; Christmann, G.; Tsintzos, S. I.; Hatzopoulos, Z.; Kavokin, A. V.

    2015-09-07

    We report observation of strong light-matter coupling in an AlGaAs microcavity (MC) with an embedded single parabolic quantum well. The parabolic potential is achieved by varying aluminum concentration along the growth direction providing equally spaced energy levels, as confirmed by Brewster angle reflectivity from a reference sample without MC. It acts as an active region of the structure which potentially allows cascaded emission of terahertz (THz) light. Spectrally and time resolved pump-probe spectroscopy reveals characteristic quantum beats whose frequencies range from 0.9 to 4.5 THz, corresponding to energy separation between relevant excitonic levels. The structure exhibits strong stimulated nonlinear emission with simultaneous transition to weak coupling regime. The present study highlights the potential of such devices for creating cascaded relaxation of bosons, which could be utilized for THz emission.

  7. Theoretical Study of Optical Microcavities Coupled by a Modulated Bragg Mirror

    NASA Astrophysics Data System (ADS)

    de Lima, A. G.; Santos, M. França; Guimarães, P. S. S.; Vasco, J. P.; Romero, K. M. Fonseca; Vinck-Posada, H.

    2011-12-01

    We study the change in coupling between two GaAs lambda-microcavities embedded in a one-dimensional photonic crystal composed of GaAs-AlGaAs Bragg mirrors when the refractive index of the region between the cavities is externally modulated in several diferent ways. We show that the coupling of the cavities can be significantly changed when the refractive index in the intercavity region is modulated with a Gaussian profile, such as could be obtained by illuminating the intercavity region with a strong laser pulse. This opens the way for the implementation of a full optical switch device. For this system we find that it is possible to delocalize an excited cavity mode whilst the fundamental mode remains confined.

  8. Distinguishing autocrine and paracrine signals in hematopoietic stem cell culture using a biofunctional microcavity platform

    NASA Astrophysics Data System (ADS)

    Müller, Eike; Wang, Weijia; Qiao, Wenlian; Bornhäuser, Martin; Zandstra, Peter W.; Werner, Carsten; Pompe, Tilo

    2016-08-01

    Homeostasis of hematopoietic stem cells (HSC) in the mammalian bone marrow stem cell niche is regulated by signals of the local microenvironment. Besides juxtacrine, endocrine and metabolic cues, paracrine and autocrine signals are involved in controlling quiescence, proliferation and differentiation of HSC with strong implications on expansion and differentiation ex vivo as well as in vivo transplantation. Towards this aim, a cell culture analysis on a polymer microcavity carrier platform was combined with a partial least square analysis of a mechanistic model of cell proliferation. We could demonstrate the discrimination of specific autocrine and paracrine signals from soluble factors as stimulating and inhibitory effectors in hematopoietic stem and progenitor cell culture. From that we hypothesize autocrine signals to be predominantly involved in maintaining the quiescent state of HSC in single-cell niches and advocate our analysis platform as an unprecedented option for untangling convoluted signaling mechanisms in complex cell systems being it of juxtacrine, paracrine or autocrine origin.

  9. Local Intensity Enhancements in Spherical Microcavities: Implications for Photonic Chemical and Biological Sensors

    NASA Technical Reports Server (NTRS)

    Fuller, Kirk A.

    2005-01-01

    In this report, we summarize recent findings regarding the use spherical microcavities in the amplification of light that is inelastically scattered by either fluorescent or Raman-active molecules. This discussion will focus on Raman scattering, with the understanding that analogous processes apply to fluorescence. Raman spectra can be generated through the use of a very strong light source that stimulates inelastic light scattering by molecules, with the scattering occurring at wavelengths shifted from that of the source and being most prominent at shifts associated with the molecules natural vibrational frequencies. The Raman signal can be greatly enhanced by exposing a molecule to the intense electric fields that arise near surfaces (typically of gold or silver) exhibiting nanoscale roughness. This is known as surface-enhanced Raman scattering (SERS). SERS typically produces gain factors of 103 - 106, but under special conditions, factors of 1010 - 1014 have been achieved.

  10. Microfluidic Devices Integrating Microcavity Surface-Plasmon-Resonance Sensors: Glucose Oxidase Binding-Activity Detection

    PubMed Central

    Amarie, Dragos; Alileche, Abdelkrim; Dragnea, Bogdan; Glazier, James A.

    2010-01-01

    We have developed miniature (≈1 μm diameter) microcavity surface-plasmon-resonance sensors (MSPRS), integrated them with microfluidics and tested their sensitivity to refractive-index changes. We tested their biosensing capability by distinguishing the interaction of glucose oxidase (Mr 160 kDa) with its natural substrate (β-D-glucose, Mr 180 Da) from its interactions with non-specific substrates (L-glucose, D-mannose and 2-deoxy-D-glucose). We ran the identical protocol we had used with the MSPRS on a Biacore 3000 instrument using their bare gold chip. Only the MSPRS was able to detect β-D-glucose binding to glucose oxidase. Each MSPRS can detect the binding to its surface of fewer than 35,000 glucose-oxidase molecules (representing 9.6 fg or 60 zmol of protein), about 106 times fewer than classical surface-plasmon-resonance biosensors. PMID:19968248

  11. Ultrastrong light-matter coupling in electrically doped microcavity organic light emitting diodes

    SciTech Connect

    Mazzeo, M.; Genco, A.; Gambino, S.; Ballarini, D.; Mangione, F.; Sanvitto, D.; Di Stefano, O.; Patanè, S.; Savasta, S.; Gigli, G.

    2014-06-09

    The coupling of the electromagnetic field with an electronic transition gives rise, for strong enough light-matter interactions, to hybrid states called exciton-polaritons. When the energy exchanged between light and matter becomes a significant fraction of the material transition energy an extreme optical regime called ultrastrong coupling (USC) is achieved. We report a microcavity embedded p-i-n monolithic organic light emitting diode working in USC, employing a thin film of squaraine dye as active layer. A normalized coupling ratio of 30% has been achieved at room temperature. These USC devices exhibit a dispersion-less angle-resolved electroluminescence that can be exploited for the realization of innovative optoelectronic devices. Our results may open the way towards electrically pumped polariton lasers.

  12. Manipulation of exciton and photon lasing in a membrane-type ZnO microcavity

    SciTech Connect

    Lai, Ying-Yu; Chen, Jee-Wei; Chang, Tsu-Chi; Lu, Tien-Chang; Chou, Yu-Hsun

    2015-03-30

    We report on the fabrication and characterization of a membrane-type ZnO microcavity (MC). The ZnO membrane was cut from a single crystalline ZnO substrate by using focused ion beam milling, and was then placed onto a SiO{sub 2} substrate by using glass microtweezers. Through changing the pumping regime, manipulation of P-band exciton lasing and whispering-gallery mode (WGM) photon lasing could be easily achieved. P-band exciton lasing was observed only when the pumping laser was focused at the center of the ZnO MC with a small pumping size because of the innate ring-shaped WGM distribution. Furthermore, the lasing threshold of the ZnO MC could be reduced to an order lower by using a larger pumping spot because of the more favorable spatial overlap between the optical gain and WGM.

  13. Distinguishing autocrine and paracrine signals in hematopoietic stem cell culture using a biofunctional microcavity platform

    PubMed Central

    Müller, Eike; Wang, Weijia; Qiao, Wenlian; Bornhäuser, Martin; Zandstra, Peter W.; Werner, Carsten; Pompe, Tilo

    2016-01-01

    Homeostasis of hematopoietic stem cells (HSC) in the mammalian bone marrow stem cell niche is regulated by signals of the local microenvironment. Besides juxtacrine, endocrine and metabolic cues, paracrine and autocrine signals are involved in controlling quiescence, proliferation and differentiation of HSC with strong implications on expansion and differentiation ex vivo as well as in vivo transplantation. Towards this aim, a cell culture analysis on a polymer microcavity carrier platform was combined with a partial least square analysis of a mechanistic model of cell proliferation. We could demonstrate the discrimination of specific autocrine and paracrine signals from soluble factors as stimulating and inhibitory effectors in hematopoietic stem and progenitor cell culture. From that we hypothesize autocrine signals to be predominantly involved in maintaining the quiescent state of HSC in single-cell niches and advocate our analysis platform as an unprecedented option for untangling convoluted signaling mechanisms in complex cell systems being it of juxtacrine, paracrine or autocrine origin. PMID:27535453

  14. Parallel Photonic Quantum Computation Assisted by Quantum Dots in One-Side Optical Microcavities

    PubMed Central

    Luo, Ming-Xing; Wang, Xiaojun

    2014-01-01

    Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions on one degree of freedom (DOF) of quantum systems, we investigate the possibility of parallel quantum computations dependent on two DOFs of photon systems. We construct deterministic hyper-controlled-not (hyper-CNOT) gates operating on the spatial-mode and the polarization DOFs of two-photon or one-photon systems by exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities. These hyper-CNOT gates show that the quantum states of two DOFs can be viewed as independent qubits without requiring auxiliary DOFs in theory. This result can reduce the quantum resources by half for quantum applications with large qubit systems, such as the quantum Shor algorithm. PMID:25030424

  15. Generation of Antibunched Light by Excited Molecules in a Microcavity Trap

    NASA Technical Reports Server (NTRS)

    DeMartini, F.; DiGiuseppe, G.; Marrocco, M.

    1996-01-01

    The active microcavity is adopted as an efficient source of non-classical light. By this device, excited by a mode-locked laser at a rate of 100 MHz, single-photons are generated over a single field mode with a nonclassical sub-poissonian distribution. The process of adiabatic recycling within a multi-step Franck-Condon molecular optical-pumping mechanism, characterized in our case by a quantum efficiency very close to one, implies a pump self-regularization process leading to a striking n-squeezing effect. By a replication of the basic single-atom excitation process a beam of quantum photon (Fock states) can be created. The new process represents a significant advance in the modern fields of basic quantum-mechanical investigation, quantum communication and quantum cryptography.

  16. Interaction-induced hopping phase in driven-dissipative coupled photonic microcavities

    NASA Astrophysics Data System (ADS)

    Rodriguez, S. R. K.; Amo, A.; Sagnes, I.; Le Gratiet, L.; Galopin, E.; Lemaître, A.; Bloch, J.

    2016-06-01

    The Bose-Hubbard model (BHM) describes bosons hopping across sites and interacting on-site. Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have recently emerged. Two coupled semiconductor microcavities constitute a model system where the hopping, interaction and decay of exciton polaritons--mixed light-matter quasiparticles--can be engineered in combination with site-selective coherent driving to implement the driven-dissipative two-site optical BHM. Here we explore the interplay of interference and nonlinearity in this system, in a regime where three distinct density profiles can be observed under identical driving conditions. We demonstrate how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields using polaritons in two-dimensional multicavity systems.

  17. Interaction-induced hopping phase in driven-dissipative coupled photonic microcavities

    PubMed Central

    Rodriguez, S. R. K.; Amo, A.; Sagnes, I.; Le Gratiet, L.; Galopin, E.; Lemaître, A.; Bloch, J.

    2016-01-01

    The Bose-Hubbard model (BHM) describes bosons hopping across sites and interacting on-site. Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have recently emerged. Two coupled semiconductor microcavities constitute a model system where the hopping, interaction and decay of exciton polaritons—mixed light-matter quasiparticles—can be engineered in combination with site-selective coherent driving to implement the driven-dissipative two-site optical BHM. Here we explore the interplay of interference and nonlinearity in this system, in a regime where three distinct density profiles can be observed under identical driving conditions. We demonstrate how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields using polaritons in two-dimensional multicavity systems. PMID:27307038

  18. Extreme events following bifurcation to spatiotemporal chaos in a spatially extended microcavity laser

    NASA Astrophysics Data System (ADS)

    Coulibaly, S.; Clerc, M. G.; Selmi, F.; Barbay, S.

    2017-02-01

    The occurrence of extreme events in a spatially extended microcavity laser has been recently reported [Selmi et al., Phys. Rev. Lett. 116, 013901 (2016), 10.1103/PhysRevLett.116.013901] to be correlated to emergence of spatiotemporal chaos. In this dissipative system, the role of spatial coupling through diffraction is essential to observe the onset of spatiotemporal complexity. We investigate further the formation mechanism of extreme events by comparing the statistical and dynamical analyses. Experimental measurements together with numerical simulations allow us to assign the quasiperiodicity mechanism as the route to spatiotemporal chaos in this system. Moreover, by investigating the fine structure of the maximum Lyapunov exponent, of the Lyapunov spectrum, and of the Kaplan-Yorke dimension of the chaotic attractor, we are able to deduce that intermittency plays a key role in the proportion of extreme events measured. We assign the observed mechanism of generation of extreme events to quasiperiodic extended spatiotemporal intermittency.

  19. Mass and Momentum Transport in Microcavities for Diffusion-Dominant Cell Culture Applications

    NASA Technical Reports Server (NTRS)

    Yew, Alvin G.; Pinero, Daniel; Hsieh, Adam H.; Atencia, Javier

    2012-01-01

    For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically-driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for microfluidic cell culture devices. We present equations to estimate the spatial transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs to travel from the microchannel to a given depth into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, physiologically-based culture conditions with low fluid shear stress.

  20. Ignition and formation dynamics of a polariton condensate on a semiconductor microcavity pillar

    NASA Astrophysics Data System (ADS)

    Antón, C.; Solnyshkov, D.; Tosi, G.; Martín, M. D.; Hatzopoulos, Z.; Deligeorgis, G.; Savvidis, P. G.; Malpuech, G.; Viña, L.

    2014-10-01

    We present an experimental study on the ignition and decay of a polariton optical parametric oscillator (OPO) in a semiconductor microcavity pillar. The combination of a continuous-wave laser pump, under quasi-phase-matching conditions, and a nonresonant, 2-ps-long pulse probe allows us to obtain the full dynamics of the system. The arrival of the probe induces a blueshift in the polariton emission, bringing the OPO process into resonance with the pump, which triggers the OPO process. We time-resolve the polariton OPO signal emission for more than 1 ns in both real space and momentum space. We fully characterize the emission of the OPO signal with spectral tomography techniques. Our interpretations are backed up by theoretical simulations based on the two-dimensional coupled Gross-Pitaevskii equation for excitons and photons.

  1. Temperature-induced tuning of emission spectra of liquid-crystal optical microcavities

    NASA Astrophysics Data System (ADS)

    Zemánek, Pavel; Pilát, Zdeněk.; Ježek, Jan; Bernatová, Silvie; Aas, Mehdi; Kiraz, Alper; Jonáš, Alexandr

    2016-12-01

    Emulsion droplets of liquid crystals (LC) suspended in water and labeled with a suitable fluorescent dye can serve as active optofluidic microcavities, since the contrast of refractive index between the LC droplets and the surrounding aqueous medium allows excitation of whispering gallery modes (WGMs) in the droplets. In addition, such emulsion droplets can be also stably trapped in three-dimensions using optical tweezers which stabilizes the droplets while investigating their spectral characteristics. We explore various combinations of fluorescently dyed LC droplets and host liquid - surfactant systems and show that the WGM emission spectrum of an optically trapped LC droplet-based cavity can be largely and (almost) reversibly tuned by controlled changes of the ambient temperature that induce phase transitions in the LC droplets. Our results indicate feasibility of this approach for creating miniature tunable sources of coherent light.

  2. Observation of bound and antibound states of cavity polariton pairs in a CuCl microcavity

    NASA Astrophysics Data System (ADS)

    Matsuura, S.; Mitsumori, Y.; Kosaka, H.; Edamatsu, K.; Miyazaki, K.; Kim, D.; Nakayama, M.; Oohata, G.; Oka, H.; Ajiki, H.; Ishihara, H.

    2014-01-01

    We observed the antibound state, as well as the bound state, for cavity polariton pairs in a planar CuCl microcavity by spectrally resolved four-wave mixing. We obtained dispersion curves of the bound and antibound states by changing the incident angle of the pump pulses corresponding to the cavity detuning. The dispersion curve for the bound state suggests that the bound state is mainly composed of a bare biexciton and is weakly coupled to the cavity photons. The dephasing time of the bound state was faster than that of a bare biexciton in a thin sample, supporting the hypothesis that the bound state is coupled to the cavity photons. On the other hand, the antibound state consists of two lower polaritons having the same spin. The clear observation of the antibound state can be qualitatively explained by the phase-space filling, which reduces the Rabi splitting.

  3. Coherent destruction of tunneling in chaotic microcavities via three-state anti-crossings

    PubMed Central

    Song, Qinghai; Gu, Zhiyuan; Liu, Shuai; Xiao, Shumin

    2014-01-01

    Coherent destruction of tunneling (CDT) has been one seminal result of quantum dynamics control. Traditionally, CDT is understood as destructive interference between two intermediate transition paths near the level crossing. CDT near the level anti-crossings, especially the “locking”, has not been thoroughly explored so far. Taking chaotic microcavity as an example, here we study the inhibition of the tunneling via the strong couplings of three resonances. While the tunneling rate is only slightly affected by each strong coupling between two modes, the destructive interference between two strong couplings can dramatically improve the inhibition of the tunneling. A “locking” point, where dynamical tunneling is completely suppressed, has even been observed. We believe our finding will shed light on researches on micro- & nano-photonics. PMID:24781881

  4. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    SciTech Connect

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai E-mail: zhanghai@fudan.edu.cn; Cao, Runan; Xu, Fei; Da, Peimei; Zheng, Gengfeng; Lu, Jian E-mail: zhanghai@fudan.edu.cn

    2016-01-11

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources.

  5. Crossover from polariton lasing to exciton lasing in a strongly coupled ZnO microcavity

    PubMed Central

    Lai, Ying-Yu; Chou, Yu-Hsun; Lan, Yu-Pin; Lu, Tien-Chang; Wang, Shing-Chung; Yamamoto, Yoshihisa

    2016-01-01

    Unlike conventional photon lasing, in which the threshold is limited by the population inversion of the electron-hole plasma, the exciton lasing generated by exciton-exciton scattering and the polariton lasing generated by dynamical condensates have received considerable attention in recent years because of the sub-Mott density and low-threshold operation. This paper presents a novel approach to generate both exciton and polariton lasing in a strongly coupled microcavity (MC) and determine the critical driving requirements for simultaneously triggering these two lasing operation in temperature <140 K and large negative polariton-exciton offset (<−133 meV) conditions. In addition, the corresponding lasing behaviors, such as threshold energy, linewidth, phase diagram, and angular dispersion are verified. The results afford a basis from which to understand the complicated lasing mechanisms in strongly coupled MCs and verify a new method with which to trigger dual laser emission based on exciton and polariton. PMID:26838665

  6. 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

  7. 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.

  8. Mono- to few-layered graphene oxide embedded randomness assisted microcavity amplified spontaneous emission source

    NASA Astrophysics Data System (ADS)

    Das, Pratyusha; Maiti, Rishi; Barman, Prahalad K.; Ray, Samit K.; Shivakiran, Bhaktha B. N.

    2016-02-01

    The realization of optoelectronic devices using two-dimensional materials such as graphene and its intermediate product graphene oxide (GO) is extremely challenging owing to the zero band gap of the former. Here, a novel amplified spontaneous emission (ASE) system based on a GO-embedded all-dielectric one-dimensional photonic crystal (1DPhC) micro-resonator is presented. The mono- to few-layered GO sheet is inserted within a microcavity formed by two 5-bilayered SiO2/SnO2 Bragg reflectors. Significantly enhanced photoluminescence (PL) emission of GO embedded in 1DPhC is explicated by studying the electric field confined within the micro-resonator using the transfer matrix method. The inherent randomness, due to fabrication limitations, in the on-average periodic 1DPhC is exploited to further enhance the PL of the optically active micro-resonator. The 1DPhC and randomness assisted field confinement reduces the ASE threshold of the mono- to few-layered weak emitter making the realization of an ASE source feasible. Consequently, ASE at the microcavity resonance and at the low-frequency band-edge of photonic stop-band is demonstrated. Variation of the detection angle from 5° to 30°, with respect to the sample surface normal allows reallocation of the defect mode ASE peak over a spectral range of 558-542 nm, making the GO-incorporated 1DPhC a novel and attractive system for integrated optic applications.

  9. 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.

  10. Isolation of high quality RNA from Phyllanthus emblica and its evaluation by downstream applications.

    PubMed

    Kumar, Avneesh; Singh, Kashmir

    2012-11-01

    Next generation sequencing is a high-throughput technique widely used for transcriptome profiling. Isolation of high quality RNA is a prerequisite for such large scale transcriptome analysis. Phyllanthus emblica is an important medicinal plant having high amount of metabolites like vitamin C, flavonoids, polyphenolic compounds, tannins, which are responsible for its wondered medicinal properties. High concentration of secondary metabolites like polysaccharides and polyphenols proved to be an obstacle in isolating RNA of good quality. Any compromise with quality of RNA affects the downstream applications and requires extra cleaning steps that further reduce RNA quantity. We have developed a protocol for isolation of high quality RNA from P. embilca. RNA was successfully assessed for downstream applications like reverse transcription polymerase chain reaction, rapid amplification of cDNA ends, mRNA library preparation, and sequencing using HiSeq(™) 2000 sequencing technology. The protocol is simple and can be completed in 4-5 h.

  11. Health-related quality of life in children with high-functioning autism.

    PubMed

    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 life of children. A cross-sectional study of children with high-functioning autism (n = 30) and peers (n = 31) was conducted using the Pediatric Quality of Life Inventory 4.0 Generic Core Scales. Children with high-functioning autism had significantly poorer health-related quality of life than peers whether reported by themselves (p < .001) or their parents (p < .001), although disagreement (intra-class coefficient = -.075) between children and parental scores suggested variance in points of view. This study specifically investigated health-related quality of life in children with high-functioning autism as compared to a sample of peers, from the child's perspective. It strengthens earlier findings that children with high-functioning autism experience poorer health-related quality of life than those without this disorder and points to the importance of clinicians working with families to identify areas in a child's life that promote or hinder their sense of well-being.

  12. Bust economics: foragers choose high quality habitats in lean times

    PubMed Central

    Dickman, Christopher R.

    2016-01-01

    In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni) during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high. PMID:26839751

  13. Hiring Highly Qualified Teachers Begins with Quality Interviews

    ERIC Educational Resources Information Center

    Clement, Mary C.

    2009-01-01

    School administrators have some tough hiring decisions to make, and an interview to select the most highly qualified applicants is critically important. Even before the mandates of No Child Left Behind, school administrators strove to hire the best new teachers. Competent, caring, qualified teachers are the keys to enhanced student achievement.…

  14. Bust economics: foragers choose high quality habitats in lean times.

    PubMed

    Bleicher, Sonny S; Dickman, Christopher R

    2016-01-01

    In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni) during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high.

  15. Technology's Achilles Heel: Achieving High-Quality Implementation

    ERIC Educational Resources Information Center

    Hall, Gene E.

    2010-01-01

    An inherent characteristic of technology education is the continual development of new technologies and creating innovative applications of already existing technologies. As exciting as these innovations can be, technology educators and school staffs are frequently challenged to accomplish high levels of implementation. The metaphor of the…

  16. Influence of the size of a micro-cavity fabricated in an optical fiber using the femtosecond laser in a form of in-line Mach-Zehnder interferometer on its refractive index sensitivity

    NASA Astrophysics Data System (ADS)

    Janik, Monika; Koba, Marcin; Bock, Wojtek J.; Śmietana, Mateusz

    2016-12-01

    This paper discusses refractive index (n) measurement capabilities of micro-cavity with various diameters (d = 40, 54 and 60μm) fabricated in optical fibers by a femtosecond laser. The bottom of the cavity intersected the fiber's core and the Mach-Zehnder interferometer effect was induced, allowing the measurement of the n of the liquid filling the cavity. After filling the cavity, a set of minima can be observed in fiber transmission spectrum which shift with change in n. Fabricated sensors exhibit high and linear sensitivity, which in the range of n=1.3333 to 1.3500 RIU barely depends on the cavity diameter in case of first observed minima. Next for different micro-cavity diameters the minima do not overlap in refractive index domain thus it is impossible to compare them in terms of the sensitivity. The highest sensitivity of up to more than 27 000 nm/RIU was obtained for the smallest cavity and the third observed minimum.

  17. Building a High-Quality Teaching Profession: Lessons from around the World

    ERIC Educational Resources Information Center

    OECD Publishing (NJ1), 2011

    2011-01-01

    The "International Summit on the Teaching Profession" brings together education ministers, union leaders and other teacher leaders from high-performing and rapidly improving education systems to review how best to improve teacher quality and the quality of teaching and learning. This background report, taking up the four themes of the summit in…

  18. 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 (...

  19. Representations of a High-Quality System of Undergraduate Education in English Higher Education Policy Documents

    ERIC Educational Resources Information Center

    Ashwin, Paul; Abbas, Andrea; McLean, Monica

    2015-01-01

    This article examines the ways in which a high-quality system of undergraduate education is represented in recent policy documents from a range of actors interested in higher education. Drawing on Basil Bernstein's ideas, the authors conceptualise the policy documents as reflecting a struggle over competing views of quality that are expressed…

  20. The Role of Central Level Staff in Supporting High Quality Instruction

    ERIC Educational Resources Information Center

    Gamble, Matthew Tanner

    2013-01-01

    The central office manages and directs a school system. In the wake of district and school reforms, the impact of the central office on schools and quality instruction has not been fully dissected. This study explores the role of the central office in the support of high quality instruction. Further, it analyzes the perceptions of those central…