Sample records for semiconductor ridge microcavity

  1. Biexcitons in semiconductor microcavities

    DEFF Research Database (Denmark)

    Borri, P.; Langbein, W.; Woggon, U.


    in the microcavity, even if the vacuum Rabi splitting exceeds the biexciton binding energy. However, the presence of a longitudinal built-in electric field that results in a Stark effect slightly reducing the binding energy compared to the value measured on a reference bare quantum well is experimentally pointed out...

  2. Exciton-polariton wakefields in semiconductor microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Terças, H., E-mail: [Physics of Information Group, Instituto de Telecomunicações, Lisbon (Portugal); Institute for Theoretical Physics, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria); Mendonça, J.T., E-mail: [Instituto de Física, Universidade de São Paulo, São Paulo SP, 05508-090 Brazil (Brazil); IPFN, Instituto Superior Técnico, 1049-001 Lisboa (Portugal)


    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.

  3. Ultranarrow polaritons in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Borri, Paola; Langbein, Wolfgang


    We have achieved a record high ratio (19) of the Rabi splitting (3.6 meV) to the polariton linewidth (190 mu eV), in a semiconductor lambda microcavity with a single 25 nm GaAs quantum well at the antinode. The narrow polariton lines are obtained with a special cavity design which reduces...

  4. Stimulated secondary emission from semiconductor microcavities

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Mizeikis, V.; Langbein, Wolfgang Werner


    We find strong influence of final-state stimulation on the time-resolved light emission dynamics from semiconductor microcavities after pulsed excitation allowing angle-resonant polariton-polariton scattering on the lower-polariton branch. The polariton dynamics can be controlled by injection of ...

  5. Coherent dynamics of biexcitons in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Borri, P.; Langbein, W.; Woggon, U.


    The dephasing time of biexcitons in a semiconductor quantum well microcavity is measured at low temperature using transient four-wave mixing spectroscopy. The homogeneous linewidth corresponding to the dephasing of the transition from the crystal ground state to the biexciton is found to be appro......The dephasing time of biexcitons in a semiconductor quantum well microcavity is measured at low temperature using transient four-wave mixing spectroscopy. The homogeneous linewidth corresponding to the dephasing of the transition from the crystal ground state to the biexciton is found...

  6. Strong Exciton-photon Coupling in Semiconductor Microcavities

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Borri, Paola; Hvam, Jørn Märcher


    The basic building block of vertical cavity surface emitting lasers (VCSELs) and high efficiency diodes, is a quantum well embedded in a semiconductor microcavity. The high finesse that may be achieved in such a cavity is utilised to get a low threshold current in the VCSELs and a high...

  7. Biexcitons or bipolaritons in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang Werner; Woggon, U


    A well-resolved nonlinear optical transition associated with biexcitons is observed in a high-quality microcavity with a Rabi splitting exceeding the binding energy of biexcitons in the embedded quantum well. This transition is identified as an induced absorption from the lower polariton to the b......A well-resolved nonlinear optical transition associated with biexcitons is observed in a high-quality microcavity with a Rabi splitting exceeding the binding energy of biexcitons in the embedded quantum well. This transition is identified as an induced absorption from the lower polariton...

  8. Directional Secondary Emission of a Semiconductor Microcavity

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Jensen, Jacob Riis; Hvam, Jørn Märcher


    We investigate the time-resolved secondary emission of a homogeneously broadened microcavity after resonant excitation. The sample consists of a 25nm GaAs single quantum well (QW) in the center of a wedged ¥ë cavity with AlAs/AlGaAs Bragg reflectors, grown by molecular beam epitaxy. At zero detun...

  9. Time-resolved photoinduced Kerr rotation in semiconductor microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumori, Y.; Kosaka, H. [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira, Aoba-ku, Sendai (Japan); CREST-JST (Japan); Kato, N.; Edamatsu, K. [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira, Aoba-ku, Sendai (Japan); Yamamoto, N.; Akahane, K. [National Institute of Information and Communications Technology, Nukuikita, Koganei-shi, Tokyo (Japan)


    We studied photoinduced Kerr effect in cavity polaritons in a semiconductor microcavity by carefully measuring the time-resolved Kerr rotation and ellipticity spectra. The Kerr rotation angle of the microcavity polaritons is a hundred times larger than a conventional single quantum well. A spectral shape analysis of the observed spectra suggests that the photoindeced Kerr effect mainly results from a line broadening of the polarions due to spin-polarized polariton-polariton scattering. Enhancement in oscillator strength also contributes to the large rotation angle. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. The physics of semiconductor microcavities. From fundamentals to nanoscale devices

    Energy Technology Data Exchange (ETDEWEB)

    Deveaud, B. (ed.) [Ecole Polytechnique Federale de Lausanne (EPFL) (Switzerland). Inst. of Quantum Electronics and Photonics


    Electron and photon confinement in semiconductor nanostructures is one of the most active areas in solid state research. Written by leading experts in solid state physics, this book provides both a comprehensive review as well as an excellent introduction to fundamental and applied aspects of light-matter coupling in microcavities. Topics covered include parametric amplification and polariton liquids, quantum fluid and non-linear dynamical effects and parametric instabilities, polariton squeezing. Bose-Einstein condensation of microcavity polaritons, spin dynamics of exciton-polaritons, polariton correlation produced by parametric scattering, progress in III-nitride distributed Bragg reflectors using AlInN/GaN materials, high efficiency planar MCLEDs, exciton-polaritons and nanoscale cavities in photonic crystals, and MBE growth of high finesse microcavities. (orig.)

  11. Charged Polaron Polaritons in an Organic Semiconductor Microcavity (United States)

    Cheng, Chiao-Yu; Dhanker, Rijul; Gray, Christopher L.; Mukhopadhyay, Sukrit; Kennehan, Eric R.; Asbury, John B.; Sokolov, Anatoliy; Giebink, Noel C.


    We report strong coupling between light and polaron optical excitations in a doped organic semiconductor microcavity at room temperature. Codepositing MoO3 and the hole transport material 4, 4' -cyclohexylidenebis[N , N -bis(4-methylphenyl)benzenamine] introduces a large hole density with a narrow linewidth optical transition centered at 1.8 eV and an absorption coefficient exceeding 104 cm-1 . Coupling this transition to a Fabry-Pérot cavity mode yields upper and lower polaron polariton branches that are clearly resolved in angle-dependent reflectivity with a vacuum Rabi splitting ℏ ΩR>0.3 eV . This result establishes a path to electrically control polaritons in organic semiconductors and may lead to increased polariton-polariton Coulombic interactions that lower the threshold for nonlinear phenomena such as polariton condensation and lasing.

  12. Higher-order photon bunching in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Assmann, M.; Veit, F.; Bayer, M.


    Quantum mechanically indistinguishable particles such as photons may show collective behavior. Therefore, an appropriate description of a light field must consider the properties of an assembly of photons instead of independent particles. We have studied multiphoton correlations up to fourth order...... in the single-mode emission of a semiconductor microcavity in the weak and strong coupling regimes. The counting statistics of single photons were recorded with picosecond time resolution, allowing quantitative measurement of the few-photon bunching inside light pulses. Our results show bunching behavior...... in the strong coupling case, which vanishes in the weak coupling regime as the cavity starts lasing. In particular, we verify the n factorial prediction for the zero-delay correlation function of n thermal light photons....

  13. Quantum correlation control for two semiconductor microcavities connected by an optical fiber (United States)

    Mohamed, A.-B. A.; Eleuch, H.


    We explore the quantum correlations for two coupled quantum wells. Each quantum well is inside a semiconductor microcavity. The two cavities are connected by an optical fiber. The study of quantum correlations, namely the geometric quantum discord, measurement-induced non-locality and negativity, reveals sudden death and sudden birth phenomena. These effects depend not only on the initial states, coupling strengths of the cavity-fiber and cavity-exciton constants, but also on the dissipation rates of the semiconductor microcavities. We show that the coupling constants control the quantum correlations.

  14. Cavity-polariton interaction mediated by coherent acoustic phonons in semiconductor microcavities

    DEFF Research Database (Denmark)

    de Lima, Mauricio; Hey, Rudolf; Santos, Paul

    The strong coupling between excitons in a quantum well (QW) and photons in a semiconductor microcavity leads to the formation of quasi-particles known as cavity-polaritons. In this contribution, we investigate their interaction with coherent acoustic phonons in the form of surface acoustic waves ...

  15. Supersonic exciton gratings: coherent inter-polariton scattering in semiconductor microcavities

    DEFF Research Database (Denmark)

    Birkedal, Dan; Vadim, Lyssenko; Hvam, Jørn Märcher


    We report on a coherent nonlinear phenomenon in a semiconductor microcavity (SMC), which has no parallel for QW excitons. When two different polariton modes of the SMC are impulsively excited they undergo normal mode oscillations (NMOs) with coherent energy exchange between the exciton and the ca...

  16. Polariton solitons and nonlinear localized states in a one-dimensional semiconductor microcavity (United States)

    Chen, Ting-Wei; Cheng, Szu-Cheng


    This paper presents numerical studies of cavity polariton solitons (CPSs) in a resonantly pumped semiconductor microcavity with an imbedded spatial defect. In the bistable regime of the well-known homogeneous polariton condensate, with proper incident wave vector and pump strength, bright and/or dark cavity solitons can be found in the presence of a spatially confined potential. The minimum pump strength required to observe the CPSs or nonlinear localized states in this parametric pump scheme is therefore reported.

  17. Influence of Carrier Cooling on the Emission Dynamics of Semiconductor Microcavity Lasers (United States)

    Hilpert, M.; Hofmann, M.; Ellmers, C.; Oestreich, M.; Schneider, H. C.; Jahnke, F.; Koch, S. W.; Rühle, W. W.; Wolf, H. D.; Bernklau, D.; Riechert, H.


    We investigate the influence of carrier relaxation on the emission dynamics of a semiconductor microcavity laser. The structure is optically excited with energies of 1.477 down to 1.346 eV (resonant excitation). The stimulated emission dynamics clearly becomes faster for decreasing excitation energy and the influence of the light hole on the emission dynamics is demonstrated. Theoretical calculations reproduce the results only if the nonequilibrium carrier dynamics is treated on the basis of a microscopic model.

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

    Energy Technology Data Exchange (ETDEWEB)

    Höfner, M., E-mail:; Sadofev, S.; Henneberger, F. [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr.15, 12489 Berlin (Germany); Kobin, B.; Hecht, S. [Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin (Germany)


    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°.

  19. To the theory of hybrid organics/semiconductor nanostructures in microcavity (United States)

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


    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.

  20. Operation of a semiconductor microcavity under electric excitation

    Energy Technology Data Exchange (ETDEWEB)

    Karpov, D. V. [Institute of Photonics, University of Eastern Finland, P.O. Box 111, Joensuu FI-80101 (Finland); ITMO University, St. Petersburg 197101 (Russian Federation); Savenko, I. G. [Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34051 (Korea, Republic of); Nonlinear Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 2601 (Australia)


    We present a microscopic theory for the description of the bias-controlled operation of an exciton-polariton-based heterostructure, in particular, the polariton laser. Combining together the Poisson equations for the scalar electric potential and Fermi quasi-energies of electrons and holes in a semiconductor heterostructure, the Boltzmann equation for the incoherent excitonic reservoir and the Gross-Pitaevskii equation for the exciton-polariton mean field, we simulate the dynamics of the system minimising the number of free parameters and build a theoretical threshold characteristic: number of particles vs applied bias. This approach, which also accounts for the nonlinear (exciton-exciton) interaction, particle lifetime, and which can, in principle, account for any relaxation mechanisms for the carriers of charge inside the heterostructure or polariton loss, allows to completely describe modern experiments on polariton transport and model devices.

  1. Exciton-polariton in graphene nano-ribbon embedded In semiconductor microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Shojaei, S., E-mail:; Imannezhad, S.


    In this paper, we investigated coupling of confined photons in the semiconductor microcavity consists of Distributed Bragg Reflectors (DBR) (Si{sub 3}N{sub 4}/SiO{sub 2} and AlAs/Al{sub 0.1}Ga{sub 0.9}As) with excitons of gapped Armchair Graphene NanoRibbon (A-GNR) that placed at the maximum of electric field amplitude inside the semiconductor microcavity. Our calculations show that the coupling between GNR's exciton and confined photon modes and appearance of vacuum Rabi splitting (VRS), is possible. By the means of Transfer Matrix Method (TMM) we obtain angle dependent reflectance spectrum and Upper, Lower Polariton Branches (UPB&LPB) for the structure. Clear anticrossing between the neutral exciton and the cavity modes with a splitting of about 3 meV obtained that can be enhanced in double-GNR. While, our calculations certify the formation of graphene based exciton-polariton, propose the enhancement of VRS by optimization of relevant parameters to implement the graphene based cavity polaritons in optoelectronic devices.

  2. Dynamical Fano-Like Interference between Rabi Oscillations and Coherent Phonons in a Semiconductor Microcavity System. (United States)

    Yoshino, S; Oohata, G; Mizoguchi, K


    We report on dynamical interference between short-lived Rabi oscillations and long-lived coherent phonons in CuCl semiconductor microcavities resulting from the coupling between the two oscillations. The Fourier-transformed spectra of the time-domain signals obtained from semiconductor microcavities by using a pump-probe technique show that the intensity of the coherent longitudinal optical phonon of CuCl is enhanced by increasing that of the Rabi oscillation, which indicates that the coherent phonon is driven by the Rabi oscillation through the Fröhlich interaction. Moreover, as the Rabi oscillation frequency decreases upon crossing the phonon frequency, the spectral profile of the coherent phonon changes from a peak to a dip with an asymmetric structure. The continuous wavelet transformation reveals that these peak and dip structures originate from constructive and destructive interference between Rabi oscillations and coherent phonons, respectively. We demonstrate that the asymmetric spectral structures in relation to the frequency detuning are well reproduced by using a classical coupled oscillator model on the basis of dynamical Fano-like interference.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai, E-mail:, E-mail: [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Cao, Runan; Xu, Fei [Department of Physics, Shanghai University, Shanghai 200444 (China); Da, Peimei; Zheng, Gengfeng [Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai 200433 (China); Lu, Jian, E-mail:, E-mail: [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China)


    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.

  4. On the origin of nonclassical light generation upon resonant excitation of a GaAs semiconductor microcavity (United States)

    Demenev, A. A.; Domaretskii, D. R.; Parakhonskii, A. L.; Lebedev, M. V.


    It was shown in JETP Lett. 102, 508 (2015) that the intensity correlation function of the emission from a high-quality-factor semiconductor microcavity under resonant optical pumping exhibits an oscillatory behavior with an unexpectedly long oscillation period and a long decay time, which fall in the nanosecond range. A further investigation demonstrates that the origin of these oscillations is not related to the weak Rabi interaction between long-lived localized exciton states in the quantum well and the electromagnetic field of the microcavity mode. It proves that the semiconductor microcavity plays a secondary role in the observation of nonclassical light: it provides the spectral selection of the modes of the pump laser. We believe that intrinsic instabilities lead to the chaotic excitation of spiking in the laser modes under a constant operating current.

  5. Large room temperature Rabi-splitting in a ZnSe/(Zn,Cd)Se semiconductor microcavity structure (United States)

    Pawlis, A.; Khartchenko, A.; Husberg, O.; As, D. J.; Lischka, K.; Schikora, D.


    Due to their large oscillator strength ZnSe microcavities with (Zn,Cd)Se quantum wells are particularly suited to investigate the photon-exciton coupling behavior in semiconductors. We have observed a strong coupling between the excitonic and photonic mode in a ZnSe microcavity with four (Zn,Cd)Se quantum wells and distributed Bragg-mirrors of ZnS and YF 3. A very large Rabi-splitting Ω>40 meV was observed at T=300 K in reflection measurements as well as in photoluminescence investigations.

  6. Magnetic-field induced bistability in a quasi-one-dimensional semiconductor microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chuanyi, E-mail:; Zhang, Weifeng


    We theoretically study the magnetic-field induced bistability in a quasi-one-dimensional semiconductor microcavity. A critical magnetic field is obtained, and the bistability appears if a magnetic field is greater than the critical value. For a positive energy detuning of the pump from the bare exciton polaritons, one bistability loop first emerges, then it divides into two loops, and finally one of them vanishes with the increasing magnetic field. This phenomenon originates from the magnetic-field modulated interactions for opposite spins. In the variational process, there are two important effects: one is a logic gate with a small variation of the excitation laser, and the other is a spin texture like skyrmion and this texture is periodic if the energy detuning varies periodically in real space, which is useful for designing the spin-dependent optoelectronic devices. - Highlights: • We study the bistability induced by a magnetic field in a microcavity. • One bistability loop can divide into two, and then the two loops return to one. • A spin texture like skyrmion and logic gate arise in the variation of bistability loop.

  7. Determination of oscillator strength of confined excitons in a semiconductor microcavity

    Directory of Open Access Journals (Sweden)

    E.A. Cotta


    Full Text Available We have achieved a significant experimental Rabi-splitting (3.4 meV for confined polaritons in a planar semiconductor λ microcavity for only a single quantum well (SQW of GaAs (10 nm placed at the antinode. The Rabi-splitting phenomena are discussed in detail based on the semiclassical theory, where two coupled harmonic oscillators (excitons and photons are used to describe the system. In this way, we can obtain the dispersion curve of polaritons, the minimum value for the cavity reflectance and the oscillator strength to reach the strong coupling regime. This approach describes an ensemble of excitons confined in a SQW and includes a dissipation component. The results present a weak coupling regime, where an enhanced spontaneous emission takes place, and a strong coupling regime, where Rabi-splitting in the dispersion curve can be observed. The theoretical results are confronted with experimental data for the reflectance behavior in resonant and off-resonant conditions and present a great accuracy. This allows us to determine the oscillator strength of the confined excitons in the SQW with great precision.

  8. Multiple kinds of emission modes in semiconductor microcavity coupled with plasmon

    Czech Academy of Sciences Publication Activity Database

    Du, L.; Mao, H.; Luo, X.; Wang, J.; Remeš, Zdeněk


    Roč. 434, č. 1 (2014), s. 74-77 ISSN 0921-4526 R&D Projects: GA MŠk LH12186 Institutional support: RVO:68378271 Keywords : plasmon * exciton * polariton * microcavity * ZnO * effective refractive index Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.319, year: 2014

  9. Competition between electronic Kerr and free carrier effects in an ultimate fast switched semiconductor microcavity

    NARCIS (Netherlands)

    Yuce, E.; Ctistis, Georgios; Claudon, Julien; Dupuy, Emmanuel; Boller, Klaus J.; Gérard, Jean-Michel; Vos, Willem L.


    We have performed ultrafast pump-probe experiments on a GaAs-AlAs microcavity with a resonance near 1300 nm in the “original” telecom band. We concentrate on ultimate-fast optical switching of the cavity resonance that is measured as a function of pump-pulse energy. We observe that at low pump-pulse

  10. Structural and optical investigations of ZnSe based semiconductor microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Pawlis, A.; Husberg, O.; Khartchenko, A.; Lischka, K.; Schikora, D. [Paderborn Univ. (Gesamthochschule) (Germany)


    This paper describes structural and optical investigations of molecular beam epitaxy grown strained ZnSe/(Zn,Cd)Se quantum wells. Strain state, cadmium content, and quantum well layer thickness have a strong influence on the emission energy, which allows a luminescence tuning between 2.25 and 2.50 eV. Furthermore a ZnSe based microcavity structure completed with ZnS/YF{sub 3} distributed Bragg mirrors was processed. These reflectors are an alternative to several epitaxial grown II-VI materials and other reported approaches with respect to oxide layers. A blueshift in the photoluminescence emission energy measured by angle resolved microcavity detuning indicates an influence of the cavity mode on the quantum well mode. (orig.)

  11. Direct evidence of reduced dynamic scattering in the lower polariton of a semiconductor microcavity

    DEFF Research Database (Denmark)

    Borri, Paola; Jensen, Jacob Riis; Langbein, Wolfgang


    The temperature dependent linewidths of homogeneously broadened GaAs/AlxGa1 - xAs microcavity polaritons are investigated. The linewidths of the lower, middle, and upper polariton resonances are measured directly from reflection spectra at normal incidence (k(parallel to) = 0). The Linewidth of t...... with theoretical predictions in literature. A non trivial temperature dependence of the linewidth is found and its physical origin is discussed....

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

    CERN Document Server

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


    We report the elliptically, close to circularly polarized lasing at $\\hbar\\omega = 1.473$ and 1.522 eV from an AlAs/AlGaAs Bragg microcavity with 12 GaAs quantum wells in the active region and chiral-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.

  13. Microcavity Plasma Devices and Arrays Fabricated in Semiconductor, Ceramic, or Metal/polymer Structures: A New Realm of Plasma Physics and Photonics Applications

    Energy Technology Data Exchange (ETDEWEB)

    Eden, J. G.


    Micro discharge, or microcavity plasma, is the broad term that has come to be associated with an emerging class of glow discharge devices in which the characteristic spatial dimension of the plasma is nominally < 1 mm. Over the past several years, our laboratory has leveraged fabrication techniques developed largely by the VLSI and MEMs communities to demonstrate a broad spectrum of semiconductor, ceramic, and multi-layer metal/polymer structures (with microcavity cross-sectional dimensions as small as 10 . 10 mu m2) that are promising for a variety of applications, including micro displays, chemical sensors, and medical diagnostics. The remarkable properties of low temperature plasmas confined to mesoscopic dimensions including picoliter . nanoliter volumes, operation at pressures up to one atmosphere (and beyond), and specific power loadings (on a continuous basis) of tens to hundreds of kW-cm3 will be discussed. The breadth of devices now available, the increasing level of functionality, and the promise of further advances as a result of fully integrating nanotechnology will be reviewed. For example, arrays as large as 500 . 500 pixels, each of which is a (50 mum)2 inverted pyramid microcavity device, have been fabricated in 100 mm (4) dia. Si wafers and operated in the rare gases and Ar/N2 gas mixtures. Also, photodetection in the ultraviolet, visible and near-infrared with microplasma devices has been observed by interfacing a low temperature plasma with a semiconductor. Carbon nanotubes grown directly within the microcavity of microplasma devices improve all key performance parameters of the device, and nanoporous Al2O3 grown onto Al by wet chemical processing yields microplasma devices of exceptional stability and lifetime. The opportunities such structures offer for accessing new avenues in plasma physics and photonics will be discussed. (Author)

  14. Competition between electronic Kerr and free-carrier effects in an ultimate-fast optically switched semiconductor microcavity

    NARCIS (Netherlands)

    Yuce, E.; Ctistis, Georgios; Claudon, J.; Dupuy, E.; Boller, Klaus J.; Gerard, J.M.; Vos, Willem L.


    We have performed ultrafast pump–probe experiments on a GaAs–AlAs microcavity with a resonance near 1300 nm in the “Original” telecom band. We concentrate on ultimate-fast optical switching of the cavity resonance that is measured as a function of pump-pulse energy. We observe that, at low

  15. Magnetic field effects on the Rabi splitting and radiative decay rates of the exciton-polariton states in a semiconductor microcavity (United States)

    Fenniche, H.; Jaziri, S.; Bennaceur, R.


    We study theoretically a particular type of semiconductor microcavity formed by a quantum well embedded inside it and the distributed Bragg reflectors presenting a gradual structure. We apply to this structure a static magnetic field along the growth direction. In the strong coupling regime between the confined exciton and cavity modes, we evaluate the polariton Rabi splitting corresponding to the two lowest lying exciton states: HH1-CB1 and HH2-CB2 as a function of the applied magnetic field. In high magnetic field and for distinct reflectivities, we find that the Rabi splitting magnitude of the HH2-CB2 exciton is close to the fundamental one (HH1-CB1). In the presence of the magnetic field, the polariton Rabi splitting can be obtained even in low reflectivity. The dispersion polariton radiative decay rates related to the two lowest lying exciton states: HH1-CB1 and HH2-CB2 are calculated for different magnetic field values. At k //=0 and in the weak coupling regime, the polariton radiative decay rates are evaluated for both the HH1-CB1 and HH2-CB2 excitons. We show that for the fundamental excitonic state, the magnetic field value which determines the transition from the weak to the strong coupling regime is different from the HH2-CB2 exciton state.

  16. Final report on LDRD project: Semiconductor surface-emitting microcavity laser spectroscopy for analysis of biological cells and microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Gourley, P.L.; McDonald, A.E. [Sandia National Labs., Albuquerque, NM (United States). Nanostructure and Semiconductor Physics Dept.; Gourley, M.F. [Washington Hospital Center, DC (United States); Bellum, J. [Coherent Technologies, Boulder, CO (United States)


    This article discusses a new intracavity laser technique that uses living or fixed cells as an integral part of the laser. The cells are placed on a GaAs based semiconductor wafer comprising one half of a vertical cavity surface-emitting laser. After placement, the cells are covered with a dielectric mirror to close the laser cavity. When photo-pumped with an external laser, this hybrid laser emits coherent light images and spectra that depend sensitively on the cell size, shape, and dielectric properties. The light spectra can be used to identify different cell types and distinguish normal and abnormal cells. The laser can be used to study single cells in real time as a cell-biology lab-on-a-chip, or to study large populations of cells by scanning the pump laser at high speed. The laser is well-suited to be integrated with other micro-optical or micro-fluidic components to lead to micro-optical-mechanical systems for analysis of fluids, particulates, and biological cells.

  17. Optical processes in microcavities

    CERN Document Server

    Chang, R K


    The dielectric microstructures act as ultrahigh Q factors optical cavities, which modify the spontaneous emission rates and alter the spatial distributions of the input and output radiation. The editors have selected leading scientists who have made seminal contributions in different aspects of optical processes in microcavities. Every attempt has been made to unify the underlying physics pertaining to microcavities of various shapes. This book begins with a chapter on the role of microcavity modes with additional chapters on how these microcavity modes affect the spontaneous and stimulated em

  18. Transient Microcavity Sensor

    CERN Document Server

    Shu, Fang-Jie; Özdemir, Şahin Kaya; Yang, Lan; Guo, Guang-Can


    A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.

  19. Dynamics of microcavity light emitters (United States)

    Roycroft, Brendan J.; Aherne, Thomas P.; Hegarty, John; Moerman, Ingrid; Van Daele, Peter; Baets, Roel G.


    In this paper we focus on the impact of planar microcavity structures on the spontaneous emission times and bandwidths of light emitting diodes. We compare microcavity and non- microcavity devices and show that the light extraction is ten times more efficient for the microcavity devices, while the small-signal modulation bandwidth remains unchanged. Bandwidths in excess of 1 GHz are obtained. The power- bandwidth figure of merit for the microcavity devices is thus of the order of ten times greater than for the non- microcavity devices. The role of photon-recycling on the bandwidth is investigated. It is found that no major reduction in the bandwidth occurs due to recycling for devices up to 85 micrometers in diameter.

  20. Biexciton dephasing in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Borri, P.; Langbein, W.; Woggon, U.


    the heavy-hole (HH) vacuum Rabi splitting is 3.6 meV, more than three times larger than the biexciton binding energy in the bare QW (1.1 meV). Due to the narrow linewidth of the polariton resonances, a well-resolved pump-induced optical absorption associated with biexcitons was observed. In this work we...

  1. Picosecond pulsed micro-module emitting near 560 nm using a frequency doubled gain-switched DBR ridge waveguide semiconductor laser (United States)

    Kaltenbach, André; Hofmann, Julian; Seidel, Dirk; Lauritsen, Kristian; Bugge, Frank; Fricke, Jörg; Paschke, Katrin; Erdmann, Rainer; Tränkle, Günther


    A miniaturized picosecond pulsed semiconductor laser source in the spectral range around 560nm is realized by integrating a frequency doubled distributed Bragg reflector ridge waveguide laser (DBR-RWL) into a micromodule. Such compact laser sources are suitable for mobile application, e.g. in microscopes. The picosecond optical pulses are generated by gain-switching which allows for arbitrary pulse repetition frequencies. For frequency conversion a periodically poled magnesium doped lithium niobate ridge waveguide crystal (PPLN) is used to provide high conversion efficiency with single-pass second harmonic generation (SHG). The coupling of the pulsed radiation into the PPLN crystal is realized by a GRIN-lens. Such types of lenses collect the divergent laser radiation and focus it into the crystal waveguide providing high coupling efficiency at a minimum of space compared to the usage of fast axis collimator(FAC)/slow axis collimator (SAC) lens combinations. The frequency doubled output pulses show a pulse width of about 60 ps FWHM and a spectral width around 0.06nm FWHM at a central wavelength of 557nm at 15Å. The pulse peak power could be determined to be more than 300mW at a repetition frequency of 40 MHz.

  2. Optimized polaritonic modes in whispering gallery microcavities (United States)

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


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

  3. Spatiotemporal Chaos Induces Extreme Events in an Extended Microcavity Laser (United States)

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


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

  4. Ultra-fast polariton dynamics in an organic microcavity

    Directory of Open Access Journals (Sweden)

    Polli D.


    Full Text Available We study an organic semiconductor microcavity operating in the strong-coupling regime using femtosecond pump-probe spectroscopy. By probing the photo-induced absorption bands, we characterize the time-dependent population densities of states in the two polariton branches. We found evidence of a scattering process from the upper-branch cavity polaritons to the exciton reservoir having a rate of (150 fs-1. A slower process similarly populates lower-branch polaritons with a rate of around (3ps-1

  5. Handbook of optical microcavities

    CERN Document Server

    Choi, Anthony H W


    An optical cavity confines light within its structure and constitutes an integral part of a laser device. Unlike traditional gas lasers, semiconductor lasers are invariably much smaller in dimensions, making optical confinement more critical than ever. In this book, modern methods that control and manipulate light at the micrometer and nanometer scales by using a variety of cavity geometries and demonstrate optical resonance from ultra-violet (UV) to infra-red (IR) bands across multiple material platforms are explored. The book has a comprehensive collection of chapters that cover a wide range

  6. Low-threshold indium gallium nitride quantum dot microcavity lasers (United States)

    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

  7. A Semiconductor Microlaser for Intracavity Flow Cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Akhil, O.; Copeland, G.C.; Dunne, J.L.; Gourley, P.L.; Hendricks, J.K.; McDonald, A.E.


    Semiconductor microlasers are attractive components for micro-analysis systems because of their ability to emit coherent intense light from a small aperture. By using a surface-emitting semiconductor geometry, we were able to incorporate fluid flow inside a laser microcavity for the first time. This confers significant advantages for high throughput screening of cells, particulates and fluid analytes in a sensitive microdevice. In this paper we discuss the intracavity microfluidics and present preliminary results with flowing blood and brain cells.

  8. Semiconductor microlasers with intracavity microfluidics for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gourley, P.L.; McDonald, A.E.


    Microfabricated electro-optical-mechanical systems are expected to play an important role in future biomedical, biochemical and environmental technologies. Semiconductor photonic materials and devices are attractive components of such systems because of their ability to generate, transmit, modulate, and detect light. In this paper the authors report investigations of light-emitting semiconductor/glass microcavities filled with simple fluids. They examine surface tension for transporting liquids into the intracavity space and study the influence of the liquid on the spectral emission of the microcavity.

  9. Sutures - ridged (United States)

    Ridged sutures ... The borders where these plates intersect are called sutures or suture lines. In an infant only a few minutes ... This makes the bony plates overlap at the sutures and creates a small ridge. This is normal ...

  10. Electromagnetically induced transparency in optical microcavities

    Directory of Open Access Journals (Sweden)

    Liu Yong-Chun


    Full Text Available Electromagnetically induced transparency (EIT is a quantum interference effect arising from different transition pathways of optical fields. Within the transparency window, both absorption and dispersion properties strongly change, which results in extensive applications such as slow light and optical storage. Due to the ultrahigh quality factors, massive production on a chip and convenient all-optical control, optical microcavities provide an ideal platform for realizing EIT. Here we review the principle and recent development of EIT in optical microcavities. We focus on the following three situations. First, for a coupled-cavity system, all-optical EIT appears when the optical modes in different cavities couple to each other. Second, in a single microcavity, all-optical EIT is created when interference happens between two optical modes. Moreover, the mechanical oscillation of the microcavity leads to optomechanically induced transparency. Then the applications of EIT effect in microcavity systems are discussed, including light delay and storage, sensing, and field enhancement. A summary is then given in the final part of the paper.

  11. Rotating optical microcavities with broken chiral symmetry

    CERN Document Server

    Sarma, Raktim; Wiersig, Jan; Cao, Hui


    We demonstrate in open microcavities with broken chiral symmetry, quasi-degenerate pairs of co-propagating modes in a non-rotating cavity evolve to counter-propagating modes with rotation. The emission patterns change dramatically by rotation, due to distinct output directions of CW and CCW waves. By tuning the degree of spatial chirality, we maximize the sensitivity of microcavity emission to rotation. The rotation-induced change of emission is orders of magnitude larger than the Sagnac effect, pointing to a promising direction for ultrasmall optical gyroscopes.

  12. Preparation and properties of ZnSe/(Zn, Cd)Se multi-quantum-well microcavities for room temperature polariton emission (United States)

    Pawlis, A.; Kharchenko, A.; Husberg, O.; Lischka, K.; Schikora, D.


    Due to their large oscillator strengths, ZnSe microcavities with (Zn, Cd)Se quantum wells are particularly suited for investigation of the photon-exciton coupling behaviour in semiconductors. We have observed a strong coupling between the excitonic and photonic modes in a ZnSe microcavity with four (Zn, Cd)Se quantum wells and distributed Bragg mirrors of ZnS and YF3. A very large Rabi splitting \\hbar \\Omega>40 meV was observed in temperature dependent photoluminescence investigations.

  13. Preparation and properties of ZnSe/(Zn, Cd)Se multi-quantum-well microcavities for room temperature polariton emission

    Energy Technology Data Exchange (ETDEWEB)

    Pawlis, A; Kharchenko, A; Husberg, O; Lischka, K; Schikora, D [Department of Physics, University of Paderborn, Warburger Strasse 100, D-33098 Paderborn (Germany)


    Due to their large oscillator strengths, ZnSe microcavities with (Zn, Cd)Se quantum wells are particularly suited for investigation of the photon-exciton coupling behaviour in semiconductors. We have observed a strong coupling between the excitonic and photonic modes in a ZnSe microcavity with four (Zn, Cd)Se quantum wells and distributed Bragg mirrors of ZnS and YF{sub 3}. A very large Rabi splitting {Dirac_h}{omega} >40 meV was observed in temperature dependent photoluminescence investigations.

  14. Low-threshold conical microcavity dye lasers

    DEFF Research Database (Denmark)

    Grossmann, Tobias; Schleede, Simone; Hauser, Mario


    We report on lasing in rhodamine 6G-doped, conical polymeric microcavities with high quality factors fabricated on a silicon substrate. Threshold pump energies as low as 3 nJ are achieved by free-space excitation in the quasistationary pumping regime with lasing wavelengths around 600 nm. Finite...

  15. Micro-Cavity Fluidic Dye Laser

    DEFF Research Database (Denmark)

    Helbo, Bjarne; Kristensen, Anders; Menon, Aric Kumaran


    We have successfully designed, fabricated and characterized a micro-cavity fluidic dye laser with metallic mirrors, which can be integrated with polymer based lab-on-a-chip microsystems without further processing steps. A simple rate-equation model is used to predict the average pumping power...

  16. Semiconductor cavity QED: Bandgap induced by vacuum fluctuations


    Espinosa-Ortega, T.; Kyriienko, O.; Kibis, O. V.; Shelykh, I. A.


    We consider theoretically a semiconductor nanostructure embedded in one-dimensional microcavity and study the modification of its electron energy spectrum by the vacuum fluctuations of the electromagnetic field. To solve the problem, a non-perturbative diagrammatic approach based on the Green's function formalism is developed. It is shown that the interaction of the system with the vacuum fluctuations of the optical cavity opens gaps within the valence band of the semiconductor. The approach ...

  17. Band gaps induced by vacuum photons in closed semiconductor cavities


    Kibis, O. V.; Arnardottir, K. B.; Shelykh, I. A.


    We consider theoretically a closed (zero-dimensional) semiconductor microcavity where confined vacuum photonic mode is coupled to electrons in valence band of the semiconductor. It is shown that vacuum-induced virtual electron transitions between valence and conduction bands result in renormalization of electron energy spectrum. As a consequence, vacuum-induced band gaps appear within the valence band. Calculated values of the band gaps are of sub-meV scale, that makes this QED effect to be m...

  18. Transverse mode-locking in microcavity lasers (United States)

    Gordon, R.; Heberle, A. P.; Cleaver, J. R. A.


    We experimentally demonstrate mode-locking between the transverse modes of a laser. A vertical-cavity surface-emitting laser with evenly-spaced transverse modes is shown to emit a train of 2.1±0.1 ps pulses with an 11 ps repetition rate and a timing jitter of 235±30 fs. Transverse mode-locking in microcavity lasers has potential to improve the compactness, stability, integrability, repetition rate tunability, and efficiency of ultrafast optical communication sources.

  19. Multimodal subcellular imaging with microcavity photoacoustic transducer. (United States)

    Tan, Zhiliang; Tang, Zhilie; Wu, Yongbo; Liao, Yanfei; Dong, Wei; Guo, Lina


    Photoacoustic microscopy (PAM) is dominantly sensitive to the endogenous optical absorption compared with the confocal microscopy which images with scattering photons. PAM has similar structure such as optical transportation system, the optical scanning, and light source with the laser scanning confocal microscopy (LSCM). In order to match the PAM with LSCM, a special design microcavity photoacoustic (PA) transducer with high sensitivity is developed to detect the photoacoustic signals induced by modulated continuous wave (CW) laser. By employing a microcavity PA transducer, a PAM can be integrated with LSCM. Thus a simultaneous multimodal imaging can be obtained with the same laser source and optical system. The lateral resolutions of the PAM and the LSCM are both tested to be better than 1.25 μm. Then subcellular multimodal imaging can be achieved. Images from the two modes are corresponding with each other but functionally complementary. Combining PAM and LSCM provides more comprehensive information for the cytological test. This technique is demonstrated for imaging red-blood cells and meristematic cells.

  20. Rabi-like splitting from large area plasmonic microcavity

    Directory of Open Access Journals (Sweden)

    Fatemeh Hosseini Alast


    Full Text Available Rabi-like splitting was observed from a hybrid plasmonic microcavity. The splitting comes from the coupling of cavity mode with the surface plasmon polariton mode; anti-crossing was observed alongside the modal conversional channel on the reflection light measurement. The hybrid device consists of a 10x10 mm2 ruled metal grating integrated onto the Fabry-Perot microcavity. The 10x10 mm2 ruled metal grating fabricated from laser interference and the area is sufficiently large to be used in the practical optical device. The larger area hybrid plasmonic microcavity can be employed in polariton lasers and biosensors.

  1. Near field mapping of coupled photonic crystal microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Vignolini, S; Wiersma, D S; Gurioli, M [LENS, Univof Florence, 50019 Sesto Fiorentino (Italy); Intonti, F; Zani, M; Riboli, F [CNISM, 50019 Sesto Fiorentino (Italy); Balet, L; Li, L H [Inst of Photonics and Nanotechnology, CNR, 00156 Roma (Italy); Francardi, M; Gerardino, A [COBRA, Eindhoven Univ of Technology, 5600 MB Eindhoven (Netherlands); Fiore, A, E-mail: gurioli@lensunifii


    We make use of near-field microscopy to image the coupling between two adjacent photonic crystal microcavities A special design of the photonic structures is adopted with selective coupling between different modes having orthogonal spatial extensions Spatial delocalization of coupled-cavity optical modes is found whenever the frequency matching condition is fulfilled On the contrary, in case of large detuning, the modes are localized in each microcavity

  2. Parity-Time-Symmetric Whispering-Gallery Microcavities (United States)


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

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

    Directory of Open Access Journals (Sweden)

    Shu-Yu Su


    Full Text Available 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.

  4. Influence of carrier relaxation on the dynamics of stimulated emission in microcavity lasers (United States)

    Hilpert, M.; Klann, H.; Hofmann, M.; Ellmers, C.; Oestreich, M.; Schneider, H. C.; Jahnke, F.; Koch, S. W.; Rühle, W. W.; Wolf, H. D.; Bernklau, D.; Riechert, H.


    The influence of carrier relaxation on the emission dynamics of a semiconductor microcavity laser is investigated using femtosecond optical excitation. For moderate excitation intensities, the dynamics of the output laser pulse becomes significantly slower when the photon energy of the pump laser is tuned from the quantum well band-gap energy towards higher energies. Theoretical calculations reproduce this trend only if the interaction-induced dephasing of the polarization driven by the pump pulse, the formation, and relaxation of the nonequilibrium carrier distribution as well as the chirp of the excitation pulse are taken into account. Additionally, band-structure effects such as excitation of light holes influence the thermalization dynamics and lead to discontinuities in the general trend.

  5. Telecom wavelength emitting single quantum dots coupled to InP-based photonic crystal microcavities (United States)

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


    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.

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

    CERN Document Server

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


    Bosons hopping across sites and interacting on-site are the essence of the Bose-Hubbard model (BHM). Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have 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 effective polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields for polaritons in two-dimensional multicavity s...

  7. Exciton Polaritons in Microcavities New Frontiers

    CERN Document Server

    Sanvitto, Daniele


    In the past decade, there has been a burst of new and fascinating physics associated to the unique properties of two-dimensional exciton polaritons, their recent demonstration of condensation under non-equilibrium conditions and all the related quantum phenomena, which have stimulated extensive research work. This monograph summarizes the current state of the art of research on exciton polaritons in microcavities: their interactions, fast dynamics, spin-dependent phenomena, temporal and spatial coherence, condensation under non-equilibrium conditions, related collective quantum phenomena and most advanced applications. The monograph is written by the most active authors who have strongly contributed to the advances in this area. It is of great interests to both physicists approaching this subject for the first time, as well as a wide audience of experts in other disciplines who want to be updated on this fast moving field.

  8. Semiconductor physics

    Energy Technology Data Exchange (ETDEWEB)

    Tuchkevich, V.M.; Frenkel, V.Y.


    This text is a collection of papers devoted mainly to the results of the research work in the field of semiconductors. Topics include photovoltaic solar energy conversion, interacting excitons in germanium and silicon, chalcogenide vitreous semiconductors, optical cooling of the nuclear spin system in a semiconductor, photon drag of electrons in semiconductors, dielectric losses in crystals, light scattering from heavily doped semiconductors, and the capacity of an abrupt asymmetric p-n junction.

  9. New ridge parameters for ridge regression

    Directory of Open Access Journals (Sweden)

    A.V. Dorugade


    Full Text Available Hoerl and Kennard (1970a introduced the ridge regression estimator as an alternative to the ordinary least squares (OLS estimator in the presence of multicollinearity. In ridge regression, ridge parameter plays an important role in parameter estimation. In this article, a new method for estimating ridge parameters in both situations of ordinary ridge regression (ORR and generalized ridge regression (GRR is proposed. The simulation study evaluates the performance of the proposed estimator based on the mean squared error (MSE criterion and indicates that under certain conditions the proposed estimators perform well compared to OLS and other well-known estimators reviewed in this article.

  10. Deformed microcavity quantum cascade lasers with directional emission

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qijie; Yan Changling; Diehl, Laurent; Yu Nanfang; Pfluegl, Christian; Belkin, Mikhail A; Capasso, Federico [School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Hentschel, Martina [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Wiersig, Jan [Institut fuer Theoretische Physik, Universitaet Magdeburg, Postfach 4120, D-39016 Magdeburg (Germany); Edamura, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi [Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu 434-8601 (Japan)], E-mail:, E-mail:


    We report the experimental realization of deformed microcavity quantum cascade lasers (QCLs) with a Limacon-shaped chaotic resonator. Directional light emission with a beam divergence of {theta}{sub parallel}{approx}33 deg. from QCLs emitting at {lambda}{approx}10 {mu}m was obtained in the plane of the cavity for deformations in the range 0.37<{epsilon}<0.43. An excellent agreement between measured and calculated far-field profiles was found. Both simulations and experiments show that the Limacon-shaped microcavity preserves whispering gallery-like modes with high Q-factors for low deformations ({epsilon}<0.50). In addition, while the measured spectra show a transition from whispering gallery-like modes to a more complex mode structure at higher pumping currents, we observed 'universal far-field behavior' for different intracavity mode distributions in the Limacon microcavity, which can be explained by the distribution of unstable manifolds in ray optics simulations. Furthermore, the performance of the deformed microcavity lasers is robust with respect to variations of the deformation near its optimum value {epsilon}=0.40, which implies that this structure reduces the requirements on photolithography fabrication. The successful realization of these microcavity lasers may lead to applications in optoelectronics.

  11. Semiconductor statistics

    CERN Document Server

    Blakemore, J S


    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  12. Ultraviolet lasing behavior in ZnO optical microcavities

    Directory of Open Access Journals (Sweden)

    Hongxing Dong


    Full Text Available Zinc oxide (ZnO optical microcavity modulated UV lasers have been attracting a wide range of research interests. As one of the most important materials in developing high quality microcavity and efficient UV–visible optoelectronic devices due to its wide band gap (3.37 eV and large exciton binding energy (∼60 meV. In this review, we summarized the latest development of ZnO optical cavity based microlasers, mainly including Fabry-Perot mode lasers and whispering gallery mode lasers. The synthesis and optical studies of ZnO optical microcavities with different morphologies were discussed in detail. Finally, we also consider that the research focus in the near future would include new nanotechnology and physical effects, such as nano/micro fabrication, surface plasmon enhancement, and quantum dot coupling, which may result in new and interesting physical phenomena.

  13. Quantum Nonlinear Optics with Polar J-Aggregates in Microcavities. (United States)

    Herrera, Felipe; Peropadre, Borja; Pachon, Leonardo A; Saikin, Semion K; Aspuru-Guzik, Alán


    We predict that an ensemble of organic dye molecules with permanent electric dipole moments embedded in a microcavity can lead to strong optical nonlinearities at the single-photon level. The strong long-range electrostatic interaction between chromophores due to their permanent dipoles introduces the desired nonlinearity of the light-matter coupling in the microcavity. We develop a semiclassical model to obtain the absorption spectra of a weak probe field under the influence of strong exciton-photon coupling with the cavity field. Using realistic parameters, we demonstrate that a cavity field with an average photon number near unity can significantly modify the absorptive and dispersive response of the medium to a weak probe field at a different frequency. Finally, we show that the system is in the regime of cavity-induced transparency with a broad transparency window for dye dimers. We illustrate our findings using pseudoisocyanine chloride (PIC) J-aggregates in currently available optical microcavities.

  14. Spin noise amplification and giant noise in optical microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhov, I. I.; Poltavtsev, S. V.; Kozlov, G. G.; Zapasskii, V. S. [Spin-Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg (Russian Federation); Kavokin, A. V. [Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Spin-Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg (Russian Federation); Lagoudakis, P. V. [Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)


    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.

  15. Semiconductor physics

    CERN Document Server

    Böer, Karl W


    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  16. Dispersion tomography of an organic photonic-wire microcavity (United States)

    Mischok, A.; Lemke, F.; Reinhardt, C.; Brückner, R.; Zakhidov, A. A.; Hintschich, S. I.; Fröb, H.; Lyssenko, V. G.; Leo, K.


    We investigate the complex mode structure in microcavities with multidimensional optical confinement. Our active material is composed of the organic blend Alq3:DCM, embedded into a microcavity containing arrays of photonic wires, facilitating strong lateral confinement. We directly record the energy dispersion for one k→ vector component while the second lateral k→ component is scanned. Thereby, we obtain a detailed dispersion tomogram of the cavity resonances, showing excellent agreement with our optical model. We are able to exceed the lasing threshold and observe stimulated emission not only from the bottom of the cavity parabola, but also from higher order modes.

  17. Black Phosphorus based One-dimensional Photonic Crystals and Microcavities

    CERN Document Server

    Kriegel, I


    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.

  18. Microcavity polariton linewidths in the weak-disorder regime

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang Werner; Woggon, U.


    Polariton linewidths have been measured in a series of high-quality microcavities with different excitonic inhomogeneous broadening in the weak-disorder regime. We show experimentally that the influence of the disorder on the polariton linewidths is canceled when the polariton energies are far...

  19. Seeding Dynamics of Nonlinear Polariton Emission from a Microcavity

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Langbein, Wolfgang Werner; Jensen, Jacob Riis


    Summary form only given. The dynamics of polaritons in microcavity samples is presently under intense debate, in particular whether or not the so-called Boser action is possible. In this work, we investigate a λ cavity with a homogeneously broadened 25 nm GaAs quantum well at the antinode...

  20. Computational Modeling of Photonic Crystal Microcavity Single-Photon Emitters (United States)

    Saulnier, Nicole A.

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

  1. Grafts for Ridge Preservation. (United States)

    Jamjoom, Amal; Cohen, Robert E


    Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome.

  2. Grafts for Ridge Preservation

    Directory of Open Access Journals (Sweden)

    Amal Jamjoom


    Full Text Available Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome.

  3. Numerical modeling of exciton-polariton Bose-Einstein condensate in a microcavity (United States)

    Voronych, Oksana; Buraczewski, Adam; Matuszewski, Michał; Stobińska, Magdalena


    A novel, optimized numerical method of modeling of an exciton-polariton superfluid in a semiconductor microcavity was proposed. Exciton-polaritons are spin-carrying quasiparticles formed from photons strongly coupled to excitons. They possess unique properties, interesting from the point of view of fundamental research as well as numerous potential applications. However, their numerical modeling is challenging due to the structure of nonlinear differential equations describing their evolution. In this paper, we propose to solve the equations with a modified Runge-Kutta method of 4th order, further optimized for efficient computations. The algorithms were implemented in form of C++ programs fitted for parallel environments and utilizing vector instructions. The programs form the EPCGP suite which has been used for theoretical investigation of exciton-polaritons. Catalogue identifier: AFBQ_v1_0 Program summary URL: Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: BSD-3 No. of lines in distributed program, including test data, etc.: 2157 No. of bytes in distributed program, including test data, etc.: 498994 Distribution format: tar.gz Programming language: C++ with OpenMP extensions (main numerical program), Python (helper scripts). Computer: Modern PC (tested on AMD and Intel processors), HP BL2x220. Operating system: Unix/Linux and Windows. Has the code been vectorized or parallelized?: Yes (OpenMP) RAM: 200 MB for single run Classification: 7, 7.7. Nature of problem: An exciton-polariton superfluid is a novel, interesting physical system allowing investigation of high temperature Bose-Einstein condensation of exciton-polaritons-quasiparticles carrying spin. They have brought a lot of attention due to their unique properties and potential applications in polariton-based optoelectronic integrated circuits. This is an out-of-equilibrium quantum system confined

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  5. High-Q hybrid 3D-2D slab-3D photonic crystal microcavity. (United States)

    Tang, Lingling; Yoshie, Tomoyuki


    The radiation loss in the escaping light cone with a two-dimensional (2D) photonic crystal slab microcavity can be suppressed by means of cladding the low-Q slab microcavity by three-dimensional woodpile photonic crystals with the complete bandgap when the resonance frequency is located inside the complete bandgap. It is confirmed that the hybrid microcavity based on a low-Q, single-defect photonic crystal slab microcavity shows improvement of the Q factor without affecting the mode volume and modal frequency. Whereas 2D slab microcavities exhibit Q saturation with an increase in the number of layers, for the analyzed hybrid microcavities with a small gap between the slab and woodpiles, the Q factor does not saturate.

  6. Ultrafast dynamics and laser action of organic semiconductors

    CERN Document Server

    Vardeny, Zeev Valy


    Spurred on by extensive research in recent years, organic semiconductors are now used in an array of areas, such as organic light emitting diodes (OLEDs), photovoltaics, and other optoelectronics. In all of these novel applications, the photoexcitations in organic semiconductors play a vital role. Exploring the early stages of photoexcitations that follow photon absorption, Ultrafast Dynamics and Laser Action of Organic Semiconductors presents the latest research investigations on photoexcitation ultrafast dynamics and laser action in pi-conjugated polymer films, solutions, and microcavities.In the first few chapters, the book examines the interplay of charge (polarons) and neutral (excitons) photoexcitations in pi-conjugated polymers, oligomers, and molecular crystals in the time domain of 100 fs-2 ns. Summarizing the state of the art in lasing, the final chapters introduce the phenomenon of laser action in organics and cover the latest optoelectronic applications that use lasing based on a variety of caviti...

  7. Simulation of single transparent molecule interaction with an optical microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Quan Haiyong; Guo Zhixiong [Department of Mechanical and Aerospace Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)


    Finite-element simulations of nanoscale molecule interaction with the evanescent radiation field of an optical resonant microcavity are conducted to characterize the detection of single transparent molecules using the microcavity as an extremely sensitive micro/nano-sensor. The model sensor is an integrated device consisting of a dielectric microdisk and a waveguide that can be nanofabricated on Si-based dielectric thin film. When the microdisk is operated at a whispering-gallery mode, a strong evanescent field arises, surrounding the periphery of the cavity. Foreign target molecules such as proteins present in the near-field will interact with the electromagnetic resonant field and induce changes to the resonance. Such induced changes are investigated in this report and their significance in the detection of single molecules for nanotechnology development is discussed.

  8. Applications of Optical Microcavity Resonators in Analytical Chemistry. (United States)

    Wade, James H; Bailey, Ryan C


    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.

  9. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai


    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  10. Exceptional points enhance sensing in an optical microcavity (United States)

    Chen, Weijian; Kaya Özdemir, Şahin; Zhao, Guangming; Wiersig, Jan; Yang, Lan


    Sensors play an important part in many aspects of daily life such as infrared sensors in home security systems, particle sensors for environmental monitoring and motion sensors in mobile phones. High-quality optical microcavities are prime candidates for sensing applications because of their ability to enhance light-matter interactions in a very confined volume. Examples of such devices include mechanical transducers, magnetometers, single-particle absorption spectrometers, and microcavity sensors for sizing single particles and detecting nanometre-scale objects such as single nanoparticles and atomic ions. Traditionally, a very small perturbation near an optical microcavity introduces either a change in the linewidth or a frequency shift or splitting of a resonance that is proportional to the strength of the perturbation. Here we demonstrate an alternative sensing scheme, by which the sensitivity of microcavities can be enhanced when operated at non-Hermitian spectral degeneracies known as exceptional points. In our experiments, we use two nanoscale scatterers to tune a whispering-gallery-mode micro-toroid cavity, in which light propagates along a concave surface by continuous total internal reflection, in a precise and controlled manner to exceptional points. A target nanoscale object that subsequently enters the evanescent field of the cavity perturbs the system from its exceptional point, leading to frequency splitting. Owing to the complex-square-root topology near an exceptional point, this frequency splitting scales as the square root of the perturbation strength and is therefore larger (for sufficiently small perturbations) than the splitting observed in traditional non-exceptional-point sensing schemes. Our demonstration of exceptional-point-enhanced sensitivity paves the way for sensors with unprecedented sensitivity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo; Wang, Zhaorong; Deng, Hui, E-mail: [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Brodbeck, Sebastian; Kamp, Martin; Schneider, Christian [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Höfling, Sven [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS (United Kingdom)


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

  12. Octagonal toroid microcavity for mechanically robust optical coupling

    Directory of Open Access Journals (Sweden)

    Ryo Suzuki


    Full Text Available Light is usually coupled to a whispering gallery mode cavity using a tapered fiber. However, it is difficult to stabilize the optical coupling against mechanical vibration because it requires sub-μm control of the gap distance between the fiber and cavity. In this study, we experimentally demonstrate mechanically robust coupling that we realize by allowing the tapered fiber to touch the sidewall of the cavity. By using an octagonal toroid microcavity, we prevent the cavity-waveguide system from over coupling and achieve critical coupling even when the fiber is in contact with the surface of the cavity. We show by numerical analysis that such a deformed microcavity is required if we need to control the coupling, since a circular cavity usually overcouples when the fiber contacts the surface. The fabricated octagonal silica toroid microcavity exhibits a quality factor of 2.2 × 104 when the tapered fiber touches a cavity with a diameter of 80 μm.

  13. Multimode laser emission from free-standing cylindrical microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Jaison, E-mail:; Radhakrishnan, P.; Nampoori, V.P.N.; Kailasnath, M.


    We report a well resolved whispering gallery mode (WGM) laser emission from a free-standing microring cavity based on a dye doped hollow polymer optical fiber (DDHPOF), which is transversely pumped by a pulsed Nd:YAG laser. The microring laser is characterized by a well-defined, low threshold pump power at which the emission spectral intensity dramatically increases and collapses into several dominant microcavity laser modes with reduced mode spacing and high Q-value. Resonant modes are excited inside the gain medium which is strongly confined along the radial direction so that the spacing of lasing modes is controlled by the diameter of the cylindrical microcavity. A variation in the free spectral range of WGM spectra from 0.23 to 0.09 nm coupled with a red-shift is observed with an increase in the diameter of DDHPOFs. - Highlights: • Different diameter free-standing cylindrical microcavity lasers have been fabricated and their performances have been evaluated. • The microring laser is characterized by a well-defined, low threshold pump power, with reduced mode spacing and high Q-value. • When the diameter of DDHPOF increases, the number of lasing peaks increases along with the decrease of the FSR as observed from our studies. • It is also found that whispering gallery lasing envelope is shifted from 559 to 571 nm (Stokes shift) with the diameter.

  14. Creation and Manipulation of Stable Dark Solitons and Vortices in Microcavity Polariton Condensates (United States)

    Ma, Xuekai; Egorov, Oleg A.; Schumacher, Stefan


    Solitons and vortices obtain widespread attention in different physical systems as they offer potential use in information storage, processing, and communication. In exciton-polariton condensates in semiconductor microcavities, solitons and vortices can be created optically. However, dark solitons are unstable and vortices cannot be spatially controlled. In the present work we demonstrate the existence of stable dark solitons and vortices under nonresonant incoherent excitation of a polariton condensate with a simple spatially periodic pump. In one dimension, we show that an additional coherent light pulse can be used to create or destroy a dark soliton in a controlled manner. In two dimensions we demonstrate that a coherent light beam can be used to move a vortex to a specific position on the lattice or be set into motion by simply switching the periodic pump structure from two-dimensional (lattice) to one-dimensional (stripes). Our theoretical results open up exciting possibilities for optical on-demand generation and control of dark solitons and vortices in polariton condensates.

  15. Macroporous Semiconductors

    Directory of Open Access Journals (Sweden)

    Helmut Föll


    Full Text Available Pores in single crystalline semiconductors come in many forms (e.g., pore sizes from 2 nm to > 10 µm; morphologies from perfect pore crystal to fractal and exhibit many unique properties directly or as nanocompounds if the pores are filled. The various kinds of pores obtained in semiconductors like Ge, Si, III-V, and II-VI compound semiconductors are systematically reviewed, emphasizing macropores. Essentials of pore formation mechanisms will be discussed, focusing on differences and some open questions but in particular on common properties. Possible applications of porous semiconductors, including for example high explosives, high efficiency electrodes for Li ion batteries, drug delivery systems, solar cells, thermoelectric elements and many novel electronic, optical or sensor devices, will be introduced and discussed.

  16. Semiconductor microlasers with intracavity microfluidics for biomedical analyses

    Energy Technology Data Exchange (ETDEWEB)

    Gourley, P.L.; McDonald, A.E. [Sandia National Labs., Albuquerque, NM (United States); Gourley, M.F. [National Institutes of Health, Bethesda, MD (United States); Bocklage, T. [Univ. of New Mexico School of Medicine, Albuquerque, NM (United States)


    Recently demonstrated microfluidic chips have the potential to be useful bioanalytical tools for DNA, protein, and cellular studies. To realize this potential, means for introducing fluids, separating their components, and detection must be integrated onto the chip. The authors have investigated semiconductor laser microcavity spectroscopy as a means for ultrasensitive detection of various fluids, cells, and particulates. Two methods for implementing this laser device are illustrated. A scanning method for reading the light signals from a static fluid in the microcavity is presented. The device has a microfabricated flow structure formed between two surfaces, a vertical cavity surface-emitting laser and a glass dielectric mirror. The resonance frequencies of this Fabry-Perot microcavity are very sensitive to the dielectric properties of the fluids confined inside the cavity. Further, the resonance linewidth or cavity Q is sensitive to the optical length of the cavity, light absorption, and light scattering from the fluid and the surfaces forming the cavity. If cells or particulates are present in the fluid they confine light transverse to the cavity length and develop additional sub-frequencies between the Fabry-Perot frequencies. Thus, the spectrum of light emitted from or transmitted through the cavity comprises a wealth of information about the cavity contents.

  17. Soliton physics with semiconductor exciton–polaritons in confined systems


    Sich, Maksym; Skryabin, Dmitry V.; Krizhanovskii, Dmitry N.


    In the past decade, there has been a significant progress in the study of non-linear\\ud polariton phenomena in semiconductor microcavities. One of the key features of nonlinear\\ud systems is the emergence of solitons. The complexity and the inherently strong\\ud nonlinearity of the polariton system made it a perfect sandpit for observing solitonic\\ud effects in half-light half-matter environment. This review focuses on the theory and the\\ud latest experimental elucidating physics as well as po...

  18. Soliton physics with semiconductor exciton-polaritons in confined systems (United States)

    Sich, Maksym; Skryabin, Dmitry V.; Krizhanovskii, Dmitry N.


    In the past decade, there has been a significant progress in the study of non-linear polariton phenomena in semiconductor microcavities. One of the key features of non-linear systems is the emergence of solitons. The complexity and the inherently strong nonlinearity of the polariton system made it a perfect sandpit for observing solitonic effects in half-light half-matter environment. This review focuses on the theory and the latest experimental elucidating physics as well as potential applications of conservative and dissipative solitons in exciton-polariton systems. xml:lang="fr"

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


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


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

  20. Cylindrical beam propagation modelling of perturbed whispering-gallery mode microcavities. (United States)

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


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

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  2. Temperature-dependent optical resonance in a thin-walled tubular oxide microcavity

    Directory of Open Access Journals (Sweden)

    Yangfu Fang


    Full Text Available This work proposes a temperature-response capability of optical resonance in tubular optical oxide microcavities. The thin wall thickness with a subwavelength scale enables these microcavities to interact with the environment effectively. By optimization of the geometries and materials, the tubular microcavities can be tuned into temperature-inert in vacuum, and the experiments support this design. The experiments prove the idea of utilizing them as temperature-inert microcavities. Contrary wavelength shifts from previous studies were observed, which can be explained with the theoretical model. Furthermore, the theoretical results of the present work suggest that novel rolled-up microtubes could act as an exceptional optical microcavity for the application in temperature response.

  3. Ridge and Furrow Fields

    DEFF Research Database (Denmark)

    Møller, Per Grau


    Ridge and furrow is a specific way of ploughing which makes fields of systematic ridges and furrows like a rubbing washboard. They are part of an overall openfield system, but the focus in this paper is on the functionality of the fields. There are many indications that agro-technological reasons...

  4. Semiconductor statistics

    CERN Document Server

    Blakemore, J S


    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  5. Semiconductor electrochemistry

    CERN Document Server

    Memming, Rüdiger


    Providing both an introduction and an up-to-date survey of the entire field, this text captivates the reader with its clear style and inspiring, yet solid presentation. The significantly expanded second edition of this milestone work is supplemented by a completely new chapter on the hot topic of nanoparticles and includes the latest insights into the deposition of dye layers on semiconductor electrodes. In his monograph, the acknowledged expert Professor Memming primarily addresses physical and electrochemists, but materials scientists, physicists, and engineers dealing with semiconductor technology and its applications will also benefit greatly from the contents.

  6. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati


    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  7. Non-linear emission properties of ZnO microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Guillet, T.; Brimont, C.; Valvin, P.; Gil, B.; Bretagnon, T. [Universite Montpellier 2, Laboratoire Charles Coulomb, UMR5221, Montpellier (France); CNRS, Laboratoire Charles Coulomb, UMR5221, Montpellier (France); Medard, F.; Mihailovic, M. [LASMEA, UMR 6602, UBP-CNRS, Aubiere (France); Zuniga-Perez, J.; Leroux, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Bouchoule, S. [LPN-CNRS, Marcoussis (France)


    Lasing in a ZnO planar microcavity is reported under optical excitation up to room temperature. The cavity presents a quality factor of 450 and the simultaneous presence of two cavity modes with different interference orders. The transition from the strong coupling to the weak coupling regime is observed at lasing threshold. The gain mechanism below T = 240 K is attributed to excitons, according to the observation of a specific gain transition within the strong coupling regime. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Solid state microcavity dye lasers fabricated by nanoimprint lithography

    DEFF Research Database (Denmark)

    Nilsson, Daniel; Nielsen, Theodor; Kristensen, Anders


    We present a solid state polymer microcavity dye laser, fabricated by thermal nanoimprint lithography (NIL) in a dye-doped thermoplast. The thermoplast poly-methylmethacrylate (PMMA) is used due to its high transparency in the visible range and its robustness to laser radiation. The laser dye...... propagating TE–TM modes. The laser cavity has the lateral shape of a trapezoid, supporting lasing modes by reflection on the vertical cavity walls. The solid polymer dye lasers emit laterally through one of the vertical cavity walls, when pumped optically through the top surface by means of a frequency...

  9. Optofluidic laser array based on stable high-Q Fabry-Pérot microcavities. (United States)

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


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

  10. Dynamical narrowing of the Rayleigh scattering ring from a semiconductor microcavity

    DEFF Research Database (Denmark)

    Langbein, W.; Hvam, Jørn Märcher


    In resonant secondary emission of light (SE), scattering by static disorder leads to coherent resonant Rayleigh scattering (RRS), while the scattering with other quasi-particles (e.g. phonons) leads to an incoherent emission called photoluminescence (PL). For a bare quantum well (QW) the SE does....... We investigate the directional SE dynamics from a MC at 5 K consisting of an 25 nm GaAs single quantum well placed in the center of a lambda -cavity having an exciton resonance of negligible inhomogeneous broadening....

  11. Oblique angle lasing in a periodically pumped organic microcavity (United States)

    Hintschich, Susanne I.; Lyssenko, Vadim G.; Sudzius, Markas; Schütte, Bernd; Fröb, Hartmut; Leo, Karl


    We investigate a planar organic microcavity under spatially periodic optical excitation. The host:guest system of Alq3:DCM is the emitting layer embedded in between two dielectric mirrors. Excitation by an interference field of two femtosecond laser pulses generates an array of lasers spaced by few microns. The far field of the cavity response shows conventional stimulated emission at k=0 and, in addition, two stripes of laser emission at oblique angles. The excitation pattern generates a periodic modification of the optical properties of the cavity, a dynamic diffraction grating with a period of few microns. This enhances the spontaneous emission in the direction of the Bragg angle, which depends on the distance of the interference stripes. Via the angle of incidence of the excitation beams, we can optically tune output angle and the wavelength of lasing. Measurements are confirmed by simulations of the mode dynamics inside a lossy cavity with small excitation spot sizes, where the local gain exceeds the total mirror and absorptive losses. We find that adjacent cavity quasimodes couple out of phase at certain separation distances, which critically depend on the quasimode radius and, thus, on the residual absorption. Thus, we gain insight into the development of coherence and mode-locking in microcavities.

  12. Whispering gallery modes in silicon nanocrystal coated microcavities

    Energy Technology Data Exchange (ETDEWEB)

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


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

  13. Raman discrimination of bacterial strains using multilayered microcavity substrates (United States)

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


    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.

  14. Ultrafast spectroscopy of semiconductors and semiconductor nanostructures

    CERN Document Server

    Shah, Jagdeep


    Ultrafast Spectroscopy of Semiconductors and Semiconductor Nanostructures Ultrafast spectroscopy of semiconductors is currently one of the most exciting areas of research in condensed-matter physics Remarkable recent progress in the generation of tunable femtosecond pulses has allowed direct investigation of the most fundamental dynamical processes in semiconductors This monograph presents some of the most striking recent advances in the field of ultrafast spectroscopy of semiconductors and their nanostructures After a brief overview of the basic concepts and of the recent advances in the techniques of ultrashort pulse generation and ultrafast spectroscopy, it discusses the physics of relaxation, tunneling and transport dynamics in semiconductors and semiconductor nanostructures following excitation by femtosecond laser pulses

  15. Electrically Injected Polariton Lasing from a GaAs-Based Microcavity under Magnetic Field

    KAUST Repository

    Bhattacharya, Pallab


    Suppression of relaxation bottleneck and subsequent polariton lasing is observed in a GaAs-based microcavity under the application of a magnetic field. The threshold injection current density is 0.32 A/cm2 at 7 Tesla.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

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

    Energy Technology Data Exchange (ETDEWEB)

    Poellmann, C.; Leierseder, U.; Huber, R. [Department of Physics, University of Regensburg, 93040 Regensburg (Germany); Galopin, E.; Lemaître, A.; Amo, A.; Bloch, J. [CNRS-Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France); Ménard, J.-M., E-mail: [Department of Physics, University of Regensburg, 93040 Regensburg (Germany); Max Planck Institute for the Science of Light, Günther-Scharowsky-Straße 1, 91058 Erlangen (Germany)


    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.

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

    CERN Document Server

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


    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 740 nm. Most remarkably, this improvement factor reaches 270 when the excitation wavelength is centered at 750 nm.

  19. Highly indistinguishable photons from a QD-microcavity with a large Purcell-factor

    DEFF Research Database (Denmark)

    Unsleber, S.; McCutcheon, Dara; Dambach, M.


    We demonstrate the emission of highly indistinguishable photons from a quasi-resonantly pumped coupled quantum dot-microcavity system operating in the weak coupling regime. Furthermore we model the degree of indistinguishability with our novel microscopic theory.......We demonstrate the emission of highly indistinguishable photons from a quasi-resonantly pumped coupled quantum dot-microcavity system operating in the weak coupling regime. Furthermore we model the degree of indistinguishability with our novel microscopic theory....

  20. Photodetachment cross-section of H- ion in a three-dimensional cubical microcavity (United States)

    Wang, De-Hua; Huan, Pang-Zhi; Zhuang, Ke-Zheng; Li, Yu-Feng; Xie, Lei


    The photodetachment of negative ions inside a two-dimensional microcavity has been studied by many researchers. As to the photodetachment of negative ions in the three-dimensional microcavity, the research is relatively little. In this paper, we study the photodetachment cross-section of H- ion inside a three-dimensional cubical microcavity for the first time. We have observed the classical dynamics of the photodetached electron inside the cubical microcavity and found out its closed orbits. Then we calculate the photodetachment cross-section of this system. It is shown that owing to the interference effects of the electron wave travelling along various closed orbits, oscillatory structures appear in the photodetachment cross-section. And the oscillatory structures depend on the laser polarization sensitively. Compared to the photodetachment of H- ion inside a square microcavity, in photodetachment of H- ion in cubical cavity the number of the closed orbits is increased and the oscillatory structure in the photodetachment cross-section becomes much more complex. Through our study, researchers can gain a deep understanding on the correspondence of the classical dynamics and the quantum mechanics. Our study may guide future experimental research in the field of the photodetachment electron dynamics inside a three-dimensional microcavity.

  1. Low Peclet number mass and momentum transport in microcavities (United States)

    Yew, A. G.; Pinero, D.; Hsieh, A. H.; Atencia, J.


    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 applications that may include microfluidic cell culture devices. We present equations to estimate the 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 length into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, low Peclet number environments with minimal fluid shear stress.

  2. Millisecond Photon Lifetime in a Slow-Light Microcavity (United States)

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


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

  3. Tunable polaritonic molecules in an open microcavity system

    Energy Technology Data Exchange (ETDEWEB)

    Dufferwiel, S.; Li, Feng, E-mail:; Giriunas, L.; Walker, P. M.; Skolnick, M. S.; Krizhanovskii, D. N., E-mail: [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Trichet, A. A. P.; Smith, J. M. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Farrer, I.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)


    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.

  4. Dual-microcavity narrow-linewidth Brillouin laser

    CERN Document Server

    Loh, William; Baynes, Frederick; Cole, Daniel; Quinlan, Franklyn; Lee, Hansuek; Vahala, Kerry; Papp, Scott; Diddams, Scott


    Ultralow noise, yet tunable lasers are a revolutionary tool in precision spectroscopy, displacement measurements at the standard quantum limit, and the development of advanced optical atomic clocks. Further applications include LIDAR, coherent communications, frequency synthesis, and precision sensors of strain, motion, and temperature. While all applications benefit from lower frequency noise, many also require a laser that is robust and compact. Here, we introduce a dual-microcavity laser that leverages one chip-integrable silica microresonator to generate tunable 1550 nm laser light via stimulated Brillouin scattering (SBS) and a second microresonator for frequency stabilization of the SBS light. This configuration reduces the fractional frequency noise to $7.8\\times10^{-14} 1/\\sqrt{Hz}$ at 10 Hz offset, which is a new regime of noise performance for a microresonator-based laser. Our system also features terahertz tunability and the potential for chip-level integration. We demonstrate the utility of our du...

  5. Optical microcavity sensing: from reactive to dissipative interactions (Conference Presentation) (United States)

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


    Ultrasensitive optical detection of nanoparticles is highly desirable for applications in early-stage diagnosis of human diseases, environmental monitoring and homeland security, but remains extremely difficult due to ultralow polarizabilities of small-sized, low-index particles. Optical whispering-gallery-mode (WGM) microcavities, with high Q factors up to 108, provide a promising platforms for label-free detection of nano-scaled objects, due to significantly enhanced light-matter interaction. The mechanisms of the conventional WGM sensors, based on the reactive (or dispersive) interaction, measure the mode shift induced by the environmental variations of refractive index, which may fail to detect low-index nanoparticles. In this work, we propose a different dissipative sensing scheme, reacting as linewidth change of WGMs, to detect single nanoparticle using a silica toroidal microcavity fabricated on a silicon substrate. In experiment, detection of single gold nanorods in aqueous environment is realized by monitoring simultaneously the linewidth change and shift of cavity mode. Besides a good consistent with the theoretical predictions, the experimental result shows that the dissipative sensing achieves a better signal-to-noise-ratio compared to the dispersive mechanism. Remarkably, by setting the probe wavelength on and off the surface plasmon resonance of the gold nanoparticles, the great potential of the dissipative sensing method to detect single lossy nanoparticles is demonstrated. This dissipative sensing method holds great potential in detecting lossy nanoparticles, and may become a promising lab-on-a-chip platform for detecting small-sized, low-index particles with ultralow polarizabilities.

  6. Nanoparticle trapping and characterization with open microcavities (Conference Presentation) (United States)

    Trichet, Aurelien; Dolan, Philip R.; James, Dean; Hughes, Gareth M.; Vallance, Claire; Smith, Jason M.


    Thanks to their low mode volume and high finesse, optical microresonators have emerged as a promising avenue to detect and measure properties of single nanoparticles such as viruses or gold nanoparticles. Thanks to the resulting electromagnetic field enhancement, small nanoparticles, viruses and even single proteins have been trapped in hollow resonators such as photonic crystals or plasmonic tweezers. Such trapping devices with sensing capabilities are on the verge of finding powerful applications in interdisciplinary science. However, the quest for a candidate bringing together in-situ detection, trapping and multiple quantitative measurements of the particle properties supported by a comprehensive understanding still remain elusive. In this work, we show that open-access microcavities fulfil these criteria. Such resonators are made up of two micro-mirrors facing each other separated by a fluid medium in which nanoparticles can diffuse. We have recorded the cavity mode spectra while nanoparticles were optically trapped. Our results demonstrate that these microcavities can be used as optical tweezers with in-situ force calibration and nanoparticle sensing capabilities, including measurement of shape anisotropy. The shift in cavity mode wavelength during a trapping event provides information on both the nanoparticle and trap properties, as well as on the trapping force holding the particle in the trap. We are able to determine in real-time the nanoparticle polarizability, i.e. its optical response to an electromagnetic field, its coefficient of friction and characterize its shape anisotropy. The high level of control in this device makes it a robust analytical tool for real-time nanoparticle characterisation and monitoring.

  7. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph


    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  8. Power semiconductors

    CERN Document Server

    Kubát, M


    The book contains a summary of our knowledge of power semiconductor structures. It presents first a short historic introduction (Chap. I) as well as a brief selection of facts from solid state physics, in particular those related to power semiconductors (Chap. 2). The book deals with diode structures in Chap. 3. In addition to fundamental facts in pn-junction theory, the book covers mainly the important processes of power structures. It describes the emitter efficiency and function of microleaks (shunts). the p +p and n + n junctions, and in particular the recent theory of the pin, pvn and p1tn junctions, whose role appears to be decisive for the forward mode not only of diode structures but also of more complex ones. For power diode structures the reverse mode is the decisive factor in pn-junction breakdown theory. The presentation given here uses engineering features (the multiplication factor M and the experimentally detected laws for the volume and surface of crystals), which condenses the presentation an...

  9. Semiconductor Laser Measurements Laboratory (United States)

    Federal Laboratory Consortium — The Semiconductor Laser Measurements Laboratory is equipped to investigate and characterize the lasing properties of semiconductor diode lasers. Lasing features such...

  10. Epitaxial Lateral Overgrowth of Semiconductors (United States)

    Zytkiewicz, Zbigniew R.

    The state of the art and recent developments of lateral overgrowth of compound semiconductors are reviewed. First we focus on the mechanism of epitaxial lateral overgrowth (ELO) from the liquid phase, highlighting the phenomena that are crucial for growing high-quality layers with large aspect ratio. Epitaxy from the liquid phase has been chosen since the equilibrium growth techniques such as liquid-phase epitaxy (LPE) are the most suitable for lateral overgrowth. We then present numerous examples for which the defect filtration in the ELO procedure is very efficient and leads to significant progress in the development of high-performance semiconductor devices made of lattice-mismatched structures. Structural perfection of seams that appear when layers grown from neighboring seeds merge is also discussed. Next, we concentrate on strain commonly found in various ELO structures and arising due to the interaction of ELO layers with the mask. Its origin, and possible ways of its control, are presented. Then we show that the thermal strain in lattice-mismatched ELO structures can be relaxed by additional tilting of ELO wings while still preserving their high quality. Finally, recent progresses in the lateral overgrowth of semiconductors, including new mask materials and liquid-phase electroepitaxial growth on substrates coated by electrically conductive masks, are presented. New versions of the ELO technique from solution and from the vapor (growth from ridges and pendeo-epitaxy) are described and compared with standard ELO. A wide range of semiconductors, including III-V compounds grown from solution and vapor-grown GaN, are used to illustrate phenomena discussed. Very often, the similar behavior of various ELO structures reveals that the phenomena presented are not related to a specific group of compounds or their growth techniques, but have a much more general nature.

  11. Physics of semiconductor lasers; Physique des lasers a semiconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Weisbuch, C. [Ecole Polytechnique, Palaiseau (France). Dept. de Physique]|[Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique de la Matiere Condensee


    We recall the various advances which have made possible the modern semiconductor laser with its outstanding performances. Although it already gained several orders of magnitude improvement in such parameters as the threshold current density or modulation speed, we are still not yet anywhere near the physical limits of operation, and quite often these have not yet been determined. We compare the two approaches to ultimate performances, namely the use of quantum boxes in active layers and the microcavity-laser structure. We show that the latter appears more promising, as it makes the best use of the Boson nature of photons, whereas the former is handicapped by the Fermion nature of electrons which severely limits the use of single quantum box systems in optoelectronic applications. In the microcavity approach, the two possibilities of pillar-type or photonic-bandgap material-based structures are described. Besides leading to the threshold-less laser with squeezed-photon number, low-noise emission, such structures would also strongly improve the performance of other light-emitting devices. (orig.).

  12. Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Qiu, M.


    Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor...

  13. Hybrid organic-inorganic semiconductor transducer for optical and electrical sensing (United States)

    Calio, A.; Cassinese, A.; Casalino, M.; Politi, J.; Barra, M.; De Stefano, L.


    Porous silicon (PSi) non-symmetric multilayers are modified by organic molecular beam deposition of an organic semiconductor, namely the N,N'-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN2). Joule evaporation of PDIF-CN2 into the PSi sponge-like matrix not only improves but also adds transducing skills, making this solid-state device a dual (optical and electrical) signal sensor for biochemical monitoring. PDIF-CN2 modified PSi optical microcavities show an increase of about 5 orders of magnitude in electric current with respect to the same bare device. This feature can be used to sense volatile substances.

  14. Millisecond Photon Lifetime in a Slow-Light Microcavity. (United States)

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


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

  15. Enhanced nonlinear optics in photonic-crystal microcavities. (United States)

    Bravo-Abad, Jorge; Rodriguez, Alejandro; Bermel, Peter; Johnson, Steven G; Joannopoulos, John D; Soljacic, Marin


    Focus Serial: Frontiers of Nonlinear Optics Nonlinear photonic-crystal microresonators offer unique fundamental ways of enhancing a variety of nonlinear optical processes. This enhancement improves the performance of nonlinear optical devices to such an extent that their corresponding operation powers and switching times are suitable for their implementation in realistic ultrafast integrated optical devices. Here, we review three different nonlinear optical phenomena that can be strongly enhanced in photonic crystal microcavities. First, we discuss a system in which this enhancement has been successfully demonstrated both theoretically and experimentally, namely, a photonic crystal cavity showing optical bistability properties. In this part, we also present the physical basis for this dramatic improvement with respect to the case of traditional nonlinear devices based on nonlinear Fabry-Perot etalons. Secondly, we show how nonlinear photonic crystal cavities can be also used to obtain complete second-harmonic frequency conversion at very low input powers. Finally, we demonstrate that the nonlinear susceptibility of materials can be strongly modified via the so-called Purcell effect, present in the resonant cavities under study.

  16. Optimisation of spontaneous four-wave mixing in a ring microcavity (United States)

    Chuprina, I. N.; An, P. P.; Zubkova, E. G.; Kovalyuk, V. V.; Kalachev, A. A.; Gol’tsman, G. N.


    A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the dispersion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numerical calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: completely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable. Presented at the Russian – British Symposium on Quantum Technologies (Moscow, 20 – 23 March 2017)

  17. Theory and measurement of the soliton self-frequency shift and efficiency in optical microcavities. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Hiroki Itobe


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

  19. Strong exciton-photon coupling in organic single crystal microcavity with high molecular orientation

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Kaname [Department of Electronics, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yamashita, Kenichi, E-mail: [Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yanagi, Hisao [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Yamao, Takeshi; Hotta, Shu [Faculty of Materials Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)


    Strong exciton-photon coupling has been observed in a highly oriented organic single crystal microcavity. This microcavity consists of a thiophene/phenylene co-oligomer (TPCO) single crystal laminated on a high-reflection distributed Bragg reflector. In the TPCO crystal, molecular transition dipole was strongly polarized along a certain horizontal directions with respect to the main crystal plane. This dipole polarization causes significantly large anisotropies in the exciton transition and optical constants. Especially the anisotropic exciton transition was found to provide the strong enhancement in the coupling with the cavity mode, which was demonstrated by a Rabi splitting energy as large as ∼100 meV even in the “half-vertical cavity surface emitting lasing” microcavity structure.

  20. Dependence of output features of a micro-cavity laser on the cavity structure (United States)

    Rong, Kepeng; Song, Haizhi; Wang, You; Yu, Hang; Wang, Shunyan; An, Guofei; Cai, He; Han, Juhong; Zhang, Wei; Wang, Hongyuan


    In this study, we analyze the characteristics of a micro-cavity laser with the size one-order larger than the lasing wavelength by employing the finite-difference time-domain (FDTD) methodology. The simulation results have been obtained under the conditions with different materials and structures of the oscillator. It is seen that the power leakage from the side wall depends on the material and structure of a micro-cavity laser system. The wall material of the micro-cavity is assumed to be BK7 glass, silver, and copper, respectively. The results indicate that the side power leakage with the wall material of BK7 glass is much more serious than those with the wall materials of silver and copper. In addition, it is demonstrated that the cavity structure is also a key factor that influences the output features of such a laser.

  1. Fundamentals of semiconductor devices

    CERN Document Server

    Lindmayer, Joseph


    Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.

  2. Generalized full-vector multi-mode matching analysis of whispering gallery microcavities. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Ruth I. Mata-Chávez


    Full Text Available 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, J.-G., E-mail:; 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. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warszawa (Poland)


    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.

  5. Reserve current analysis in semiconductor insulator semiconductor ...

    African Journals Online (AJOL)

    Reserve current analysis in semiconductor insulator semiconductor (SIS) solar cells. H Yakubu, PK Mensah. Abstract. No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp. 1-4. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

  6. Detecting single DNA molecule interactions with optical microcavities (Presentation Recording) (United States)

    Vollmer, Frank


    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).

  7. Handbook of spintronic semiconductors

    CERN Document Server

    Chen, Weimin


    Offers a review of the field of spintronic semiconductors. This book covers a range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, developments in theory and experimental techniques and potential device applications.

  8. FDTD and transfer matrix methods for evaluating the performance of photonic crystal based microcavities for exciton-polaritons (United States)

    Liu, Yi-Cheng; Byrnes, Tim


    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.

  9. Superconducting detectors for semiconductor quantum photonics

    Energy Technology Data Exchange (ETDEWEB)

    Reithmaier, Guenther M.


    In this thesis we present the first successful on-chip detection of quantum light, thereby demonstrating the monolithic integration of superconducting single photon detectors with individually addressable semiconductor quantum dots in a prototypical quantum photonic circuit. Therefore, we optimized both the deposition of high quality superconducting NbN thin films on GaAs substrates and the fabrication of superconducting detectors and successfully integrated these novel devices with GaAs/AlGaAs ridge waveguides loaded with self-assembled InGaAs quantum dots.

  10. Optimisation of the prism coupling of optical whispering-gallery-mode microcavities (United States)

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


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

  11. All-optical tunable buffering with coupled ultra-high Q whispering gallery mode microcavities. (United States)

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


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

  12. Recycling of guided mode light emission in planar microcavity light emitting diodes (United States)

    De Neve, H.; Blondelle, J.; Van Daele, P.; Demeester, P.; Baets, R.; Borghs, G.


    Results are presented on planar microcavity light emitting diodes with different device diameters. A record external quantum efficiency of 20% is achieved for a 1.5 mm light emitting diode. The strong dependence of the quantum efficiency on current density and device size are compared with theoretical results. A good correspondence is obtained when spectral broadening and photon recycling are taken into account.

  13. Temperature Dependence of the Polariton Linewidth in a GaAs Quantum Well Microcavity

    DEFF Research Database (Denmark)

    Borri, P.; Jensen, Jacob Riis; Langbein, W.


    The temperature dependent linewidths of the polariton resonances in a GaAs/AlGaAs single quantum well microcavity are measured. Due to the dominant homogeneous broadening of the investigated resonances, a direct linewidth analysis of the reflectivity spectra allows us to investigate the role of s...

  14. Performance of integrated optical microcavities for refractive index and fluorescence sensing

    NARCIS (Netherlands)

    Krioukov, E.; Greve, Jan; Otto, Cornelis


    The performance of a novel sensor based on an integrated optical (IO) disk microcavity (MC) is theoretically studied. The MC is a resonant waveguide structure in which multiple interference of a guided mode occurs. At resonance, the MC is extremely sensitive to refractive index changes and it

  15. Four stages of pressure ridging (United States)

    Hopkins, Mark A.


    The pressure ridging process is simulated using a two-dimensional particle model. Blocks are broken from an intact sheet of relatively thin lead ice pushed against a thick, multiyear floe at a constant speed. The blocks of ice rubble accumulate to form the ridge sail and keel. During the simulations the energy consumed in ridge growth, including dissipation, is explicitly calculated. On the basis of the results of simulations performed with the model, the ridging process can be divided into four distinct stages. The first stage begins with an intact sheet of lead ice impacting a floe and ends when the sail reaches its maximum height. In the second stage the ridge keel deepens and widens. The stage ends when the maximum keel draft is reached. In the third stage the direction of growth is leadward creating a rubble field of more or less uniform thickness. The third stage ends when the supply of thin ice is exhausted. In the fourth stage the rubble field is compressed between converging floes. The results of simulations establish the dependence of ridging energetics in the first and second stages on the thickness of the ice sheet and the amount of ice pushed into the ridge. The average profiles of the simulated ridges delineate the growth process in the first, second, and third stages. The energetics and profiles of the fourth stage were described by Hopkins et al. [1991]. Lead ice extents of up to 1300 m are pushed into ridges to determine maximum sail heights, keel drafts, and ridging forces.

  16. Graphene-supported plasmonic whispering-gallery mode in a metal-coated microcavity for sensing application with ultrahigh sensitivity (United States)

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


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

  17. Application of whispering-gallery-mode optical microcavities for detection of silver nanoparticles in an aqueous medium (United States)

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


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

  18. Observations of cavity polaritons in one-dimensional photonic crystals containing a liquid-crystalline semiconductor based on perylene bisimide units (United States)

    Sakata, T.; Suzuki, M.; Yamamoto, T.; Nakanishi, S.; Funahashi, M.; Tsurumachi, N.


    We investigated the optical transmission properties of one-dimensional photonic crystal (1D-PC) microcavity structures containing the liquid-crystalline (LC) perylene tetracarboxylic bisimide (PTCBI) derivative. We fabricated the microcavity structures for this study by two different methods and observed the cavity polaritons successfully in both samples. For one sample, since the PTCBI molecules were aligned in the cavity layer of the 1D-PC by utilizing a friction transfer method, vacuum Rabi splitting energy was strongly dependent on the polarization of the incident light produced by the peculiar optical features of the LC organic semiconductor. For the other sample, we did not utilize the friction transfer method and did not observe such polarization dependence. However, we did observe a relatively large Rabi splitting energy of 187 meV, probably due to the improvement of optical confinement effect.

  19. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng


    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  20. Semiconductor devices physics and technology

    CERN Document Server

    Sze, Simon


    Semiconductor Devices: Physics and Technology, Third Edition is an introduction to the physical principles of modern semiconductor devices and their advanced fabrication technology. It begins with a brief historical review of major devices and key technologies and is then divided into three sections: semiconductor material properties, physics of semiconductor devices and processing technology to fabricate these semiconductor devices.

  1. Python Scripts for Automation of Current-Voltage Testing of Semiconductor Devices (FY17) (United States)


    ARL-TR-7923 ● JAN 2017 US Army Research Laboratory Python Scripts for Automation of Current- Voltage Testing of Semiconductor...Laboratory Python Scripts for Automation of Current- Voltage Testing of Semiconductor Devices (FY17) by Bryan H Zhao Oak Ridge Institute for Science...January 2017 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Python Scripts for Automation of Current-Voltage

  2. Ridges on Europa (United States)


    This is the highest resolution picture ever taken of the Jupiter moon, Europa. The area shown is about 5.9 by 9.9 miles (9.6 by 16 kilometers) and the smallest visible feature is about the size of a football field. In this view, the ice-rich surface has been broken into a complex pattern by cross-cutting ridges and grooves resulting from tectonic processes. Sinuous rille-like features and knobby terrain could result from surface modifications of unknown origins. Small craters of possible impact origin range in size from less than 330 feet (100 meters) to about 1300 feet (400 meters) across are visible.This image was taken by the solid state imaging television camera aboard the Galileo during its fourth orbit around Jupiter, at a distance of 2060 miles (3340 kilometers). The picture is centered at 325 degrees West, 5.83 degrees North. North is toward the top of this image, with the sun shining from the right.The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at Background information and educational context for the images can be found at URL

  3. Semiconductor Electrical Measurements Laboratory (United States)

    Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...

  4. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro


    This book presents a detailed description of the basic physics of semiconductors. All the important equations describing the properties of these materials are derived without the help of other textbooks. The reader is assumed to have only a basic command of mathematics and some elementary semiconductor physics. The text covers a wide range of important semiconductor phenomena, from the simple to the advanced. Examples include recent progress in semiconductor quantum structures such as two-dimensional electron-gas systems, ballistic transport, the quantum Hall effect, the Landauer formula, the Coulomb blockade and the single-electron transistor.

  5. Growth of a tectonic ridge

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, R.W.; Messerich, J.A. [Geological Survey, Denver, CO (United States); Johnson, A.M. [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth and Atmospheric Sciences


    The 28 June 1992 Landers, California, earthquake of M 7.6 created an impressive record of surface rupture and ground deformation. Fractures extend over a length of more than 80 km including zones of right-lateral shift, steps in the fault zones, fault intersections and vertical changes. Among the vertical changes was the growth of a tectonic ridge described here. In this paper the authors describe the Emerson fault zone and the Tortoise Hill ridge including the relations between the fault zone and the ridge. They present data on the horizontal deformation at several scales associated with activity within the ridge and belt of shear zones and show the differential vertical uplifts. And, they conclude with a discussion of potential models for the observed deformation.

  6. MBE-grown semiconductor nanostructures with electronic and photonic confinement

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis

    In this thesis the realization of semiconductor nanostructures in the InAlGaAs material system with molecular beam epitaxy (MBE) is described, as well as the characterization of their optical properties. First, the growth conditions used for different materials and surfaces are given, and the gen......In this thesis the realization of semiconductor nanostructures in the InAlGaAs material system with molecular beam epitaxy (MBE) is described, as well as the characterization of their optical properties. First, the growth conditions used for different materials and surfaces are given......, and the general capabilities of the MBE-systems are demonstrated, with respect to growth of structures with varying thicknesses/alloy compositions, and the synthesis of alloys, so-called digital alloying. In the first main part of the thesis a group of low-dimensional structures are described, the so......As, InGaAs and InAlGaAs is decribed, and it is shown how structures with very uniform quantum dots at energies near the visible red part of the spectrum may be realized. The second main part of the thesis deals with the growth of optical microcavities, where the light is strongly interacting...

  7. Semiconductor radiation detectors. Device physics

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [Max-Planck-Institut fuer Physik, Muenchen (Germany)]|[Max-Planck-Institut fuer Extraterrestrische Physik, Garching (Germany). Semiconductor Lab.


    The following topics were dealt with: semiconductor radiation detectors, basic semiconductor structures, semiconductors, energy measurement, radiation-level measurement, position measurement, electronics of the readout function, detectors with intrinsic amplification, detector technology, device stability, radiation hardness and device simulation.

  8. Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances (United States)

    Peng, Pai; Liu, Yong-Chun; Xu, Da; Cao, Qi-Tao; Lu, Guowei; Gong, Qihuang; Xiao, Yun-Feng


    Quantum manipulation is challenging in localized-surface plasmon resonances (LSPRs) due to strong dissipations. To enhance quantum coherence, here we propose to engineer the electromagnetic environment of LSPRs by placing metallic nanoparticles (MNPs) in optical microcavities. An analytical quantum model is first built to describe the LSPR-microcavity interaction, revealing the significantly enhanced coherent radiation and the reduced incoherent dissipation. Furthermore, when a quantum emitter interacts with the LSPRs in the cavity-engineered environment, its quantum yield is enhanced over 40 times and the radiative power over one order of magnitude, compared to those in the vacuum environment. Importantly, the cavity-engineered MNP-emitter system can enter the strong coupling regime of cavity quantum electrodynamics, providing a promising platform for the study of quantum plasmonics, quantum information processing, precise sensing, and spectroscopy.

  9. Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon. (United States)

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


    Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ≈ 9300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 pg/mm(2). Highest sensitivity, irrespective of the dissociation constant K(d), is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1 μg/ml. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Engineering the Losses and Beam Divergence in Arrays of Patch Antenna Microcavities for Terahertz Sources (United States)

    Madéo, Julien; Pérez-Urquizo, Joel; Todorov, Yanko; Sirtori, Carlo; Dani, Keshav M.


    We perform a comprehensive study on the emission from finite arrays of patch antenna microcavities designed for the terahertz range by using a finite element method. The emission properties including quality factors, far-field pattern, and photon extraction efficiency are investigated for etched and non-etched structures as a function of the number of resonators, the dielectric layer thickness, and period of the array. In addition, the simulations are achieved for lossy and perfect metals and dielectric layers, allowing to extract the radiative and non-radiative contributions to the total quality factors of the arrays. Our study shows that this structure can be optimized to obtain low beam divergence (FWHM 50% while keeping a strongly localized mode. These results show that the use of these microcavities would lead to efficient terahertz emitters with a low divergence vertical emission and engineered losses.

  11. The impact of microcavity wire width on polariton soliton existence and multistability (United States)

    Slavcheva, G.; Koleva, M. V.; Pimenov, A.


    We have developed a model of the nonlinear polariton dynamics in realistic 3D non-planar microcavity wires in the driven-dissipative regime. We find that the typical microcavity optical bistability evolves into multistability upon variation of the model parameters. The origin of the multistability is discussed in detail. We apply linear perturbation analysis to modulational instabilities, and identify conditions for localisation of composite multi-mode polariton solitons in the triggered parametric oscillator regime. Further, we demonstrate stable polariton soliton propagation in tilted and tapered waveguides, and determine maximum tilt angles for which solitons still exist. Additionally, we study soliton amplitude and velocity dependence on the wire width, with a view to engineering quantum photonic devices.

  12. Investigation on the extended range of absorbing film for a microcavity enhanced graphene photodetector (United States)

    Liu, Hai-Xia; Liu, Kai-Ming; Niu, Yan-Xiong


    Microcavity is the preferred graphene-based photodetector structure for its perfect feature of narrow spectral width and absorption enhancement, thus its application sheds light on ultra-fast detection in optic telecommunication and sensing fields. Due to an extremely thin film of graphene, the present study naturally deems it essential to locate the graphene in the exact position of resonant peak intensity. Here an extended graphene position margin in asymmetric planar microcavity with absorption higher than 97.35% was demonstrated. The shift of the centre wavelength caused by graphene was revealed to be non-negligible for telecommunication applications and graphene applied devices. The maximum shift beyond the designed wavelength of 1550 nm has reached 1.07 nm in the λ/2 cavity, which may have severe impact on the DWDM system. Our theoretical investigation amplifies the absorption features and the parasitical spectrum alterations of a designed photodetector with graphene.

  13. Scalable photonic quantum computing assisted by quantum-dot spin in double-sided optical microcavity. (United States)

    Wei, Hai-Rui; Deng, Fu-Guo


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Veluthandath, Aneesh V.; Bisht, Prem B., E-mail: [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)


    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.

  15. Single-particle trapping, orbiting, and rotating in a microcavity using microfluidics (United States)

    Shen, Feng; Xu, Min; Wang, Zheng; Liu, ZhaoMiao


    With the aim of deepening the fundamental understanding of particle flow behaviors in inertial microfluidics, a mechanism of collision-triggered particle trapping in a confined rectangular microcavity (400 × 400 µm2) using microvortices is proposed, and an intriguing phenomenon that the orbit area of large particles is larger than that of small particles (diameter range of 22-38 µm) under the same flow conditions (Reynolds number = 178) is observed, which is in contrast to that indicated in previous reports. Moreover, the flow field structures of the microvortices are studied by micro-particle image velocimetry (micro-PIV), and the rotating behavior of a single particle (diameter = 40 µm) during orbiting is first measured experimentally. The results are expected to provide useful guidelines for the applications of microcavity-based microfluidics.

  16. Electrically-pumped organic laser device with a coupled microcavity structure (United States)

    Liu, Xingyuan; Lin, Jie; Li, Yantao; Qu, Songnan


    Lasing action in electrically pumped organic laser device is demonstrated. A DCM laser dye doped Alq film serves as the active layer. High reflective and low loss electrical contacts are used to form a high quality factor coupled microcavity. Single longitudinal cavity mode is obtained at 618 nm with a threshold current density of 612 mAcm-2 under room temperature continuous wave operation.

  17. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried


    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  18. High energy semiconductor switch (United States)

    Risberg, R. L.


    The objective was a controller for electric motors. By operating standard Nema B induction motors at variable speed a great deal of energy is saved. This is especially true in pumping and air conditioning applications. To allow wider use of variable speed AC drives, and to provide improved performance, a better semiconductor switch was sought. This was termed the High Energy Semiconductor Switch.

  19. Semiconductor radiation detection systems

    CERN Document Server


    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  20. Semiconductor Research Experimental Techniques

    CERN Document Server

    Balkan, Naci


    The book describes the fundamentals, latest developments and use of key experimental techniques for semiconductor research. It explains the application potential of various analytical methods and discusses the opportunities to apply particular analytical techniques to study novel semiconductor compounds, such as dilute nitride alloys. The emphasis is on the technique rather than on the particular system studied.

  1. Spin physics in semiconductors

    CERN Document Server

    Dyakonov, Mikhail I


    This book describes beautiful optical and transport phenomena related to the electron and nuclear spins in semiconductors with emphasis on a clear presentation of the physics involved. Recent results on quantum wells and quantum dots are reviewed. The book is intended for students and researchers in the fields of semiconductor physics and nanoelectronics.

  2. Monitoring of benzene-induced hematotoxicity in mice by serial leukocyte counting using a microcavity array. (United States)

    Hosokawa, Masahito; Asami, Marie; Yoshino, Tomoko; Tsujimura, Noriyuki; Takahashi, Masayuki; Nakasono, Satoshi; Tanaka, Tsuyoshi; Matsunaga, Tadashi


    Monitoring of hematotoxicity, which requires serial blood collection, is difficult to carry out in small animals due to a lack of non-invasive, individual animal-appropriate techniques that enable enumeration of leukocyte subsets from limited amounts of whole blood. In this study, a microfluidic device equipped with a microcavity array that enables highly efficient separation of leukocytes from submicroliters of whole blood was applied for hematotoxicity monitoring in mice. The microcavity array can specifically separate leukocytes from whole blood based on differences in the size and deformability between leukocytes and other blood cells. Mouse leukocytes recovered on aligned microcavities were continuously processed for image-based immunophenotypic analysis. Our device successfully recovered almost 100% of mouse leukocytes in 0.1 μL of whole blood without the effect of serial blood collection such as changes in body weight and total leukocyte count. We assessed benzene-associated hematotoxicity in mice using this system. Mice were administered with benzene once daily and the depression of leukocyte numbers induced in individual mice was successfully monitored from tail vein blood collected every other day for 2 weeks. Serial monitoring of the leukocyte number in individual mice will contribute to the understanding of hematotoxicity and reduction of the number of animal experiment trials. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Linear and nonlinear microwave responses of a microwave photonic filter based on a photonic crystal microcavity (United States)

    Long, Yun; Zhang, Yong; Zhang, Xinliang; Xia, Jinsong; Dong, Jianji; Wang, Jian


    We propose and demonstrate an ultracompact bandpass microwave photonic filter (MPF) based on a silicon photonic crystal (PhC) microcavity. Taking the fabricated PhC microcavity as an example, we comprehensively investigate both the linear and nonlinear microwave responses of the MPF based on silicon waveguide devices. Two cases are discussed in the experiment, i.e., the optical carrier wavelength is located on the left or right side of the notch resonant wavelength of the PhC microcavity. The experimental results agree well with the theoretical analyses. For the former case, the central frequency of MPF increases monotonically when fixing the optical carrier wavelength and increasing the optical carrier power. For the latter case, the nonlinear response at a fixed optical carrier wavelength shows a decrease first and then an increase in the central frequency of MPF when increasing the optical carrier power. A jump of the response is observed in the switching process. Moreover, we also observe an interesting bistable microwave response in the experiment under an optical carrier power of around -2.6 dBm in the latter case.

  4. Phase sensitive properties and coherent manipulation of a photonic crystal microcavity. (United States)

    Quiring, Wadim; Jonas, Björn; Förstner, Jens; Rai, Ashish K; Reuter, Dirk; Wieck, Andreas D; Zrenner, Artur


    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.

  5. Nanoantenna-Microcavity Hybrids with Highly Cooperative Plasmonic-Photonic Coupling. (United States)

    Liu, Jui-Nung; Huang, Qinglan; Liu, Keng-Ku; Singamaneni, Srikanth; Cunningham, Brian T


    Nanoantennas offer the ultimate spatial control over light by concentrating optical energy well below the diffraction limit, whereas their quality factor (Q) is constrained by large radiative and dissipative losses. Dielectric microcavities, on the other hand, are capable of generating a high Q-factor through an extended photon storage time but have a diffraction-limited optical mode volume. Here we bridge the two worlds, by studying an exemplary hybrid system integrating plasmonic gold nanorods acting as nanoantennas with an on-resonance dielectric photonic crystal (PC) slab acting as a low-loss microcavity and, more importantly, by synergistically combining their advantages to produce a much stronger local field enhancement than that of the separate entities. To achieve this synergy between the two polar opposite types of nanophotonic resonant elements, we show that it is crucial to coordinate both the dissipative loss of the nanoantenna and the Q-factor of the low-loss cavity. In comparison to the antenna-cavity coupling approach using a Fabry-Perot resonator, which has proved successful for resonant amplification of the antenna's local field intensity, we theoretically and experimentally show that coupling to a modest-Q PC guided resonance can produce a greater amplification by at least an order of magnitude. The synergistic nanoantenna-microcavity hybrid strategy opens new opportunities for further enhancing nanoscale light-matter interactions to benefit numerous areas such as nonlinear optics, nanolasers, plasmonic hot carrier technology, and surface-enhanced Raman and infrared absorption spectroscopies.

  6. Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities (United States)

    Heng, Hang; Wang, Rong


    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.

  7. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan


    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  8. Ridge augmentation in implant dentistry

    Directory of Open Access Journals (Sweden)

    Manoj Goyal


    Full Text Available Dimensional changes in the alveolar ridge after extraction often compromises on achieving optimal implant stability and placement of implants in the right prosthodontic positions. These situations demand augmentation of the residual ridge to achieve successful implant placement and long-term survival. Although the available literature speaks of an overabundance of techniques and agents for ridge augmentation, there is a relative paucity of quality evidence to guide the selection of suitable techniques and material. Henceforth, this paper is an endeavor to develop and describe an evidence-based decision pathway for the selection of suitable techniques for various clinical situations. Additionally, a descriptive overview of various techniques and materials is presented.

  9. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W


    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  10. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati


    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  11. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K


    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  12. Spin physics in semiconductors

    CERN Document Server


    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  13. Mid-ocean ridges, InRidge and the future

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.; Mukhopadhyay, R.; Drolia, R.K.; Ray, Dwijesh

    of Scientific and Industrial Research, New Delhi, has earmarked ridge studies as a thrust programme for the X 5 - year plan. Presently, science plans and proposal are afoot to turn this ?dream? into a reality. 1. Maury, M. F., Physical Geography...

  14. Fermi polaron-polaritons in charge-tunable atomically thin semiconductors (United States)

    Sidler, Meinrad; Back, Patrick; Cotlet, Ovidiu; Srivastava, Ajit; Fink, Thomas; Kroner, Martin; Demler, Eugene; Imamoglu, Atac


    The dynamics of a mobile quantum impurity in a degenerate Fermi system is a fundamental problem in many-body physics. The interest in this field has been renewed due to recent ground-breaking experiments with ultracold Fermi gases. Optical creation of an exciton or a polariton in a two-dimensional electron system embedded in a microcavity constitutes a new frontier for this field due to an interplay between cavity coupling favouring ultralow-mass polariton formation and exciton-electron interactions leading to polaron or trion formation. Here, we present cavity spectroscopy of gate-tunable monolayer MoSe2 (ref. ) exhibiting strongly bound trion and polaron resonances, as well as non-perturbative coupling to a single microcavity mode. As the electron density is increased, the oscillator strength determined from the polariton splitting is gradually transferred from the higher-energy repulsive exciton-polaron resonance to the lower-energy attractive exciton-polaron state. Simultaneous observation of polariton formation in both attractive and repulsive branches indicates a new regime of polaron physics where the polariton impurity mass can be much smaller than that of the electrons. Our findings shed new light on optical response of semiconductors in the presence of free carriers by identifying the Fermi polaron nature of excitonic resonances and constitute a first step in investigation of a new class of degenerate Bose-Fermi mixtures.

  15. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel


    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  16. Defects in semiconductor nanostructures (United States)

    Singh, Vijay A.; Harbola, Manoj K.; Pathak, Praveen


    Impurities play a pivotal role in semiconductors. One part in a million of phosphorous in silicon alters the conductivity of the latter by several orders of magnitude. Indeed, the information age is possible only because of the unique role of shallow impurities in semiconductors. Although work in semiconductor nanostructures (SN) has been in progress for the past two decades, the role of impurities in them has been only sketchily studied. We outline theoretical approaches to the electronic structure of shallow impurities in SN and discuss their limitations. We find that shallow levels undergo a SHADES (SHAllow-DEep-Shallow) transition as the SN size is decreased. This occurs because of the combined effect of quantum confinement and reduced dielectric constant in SN. Level splitting is pronounced and this can perhaps be probed by ESR and ENDOR techniques. Finally, we suggest that a perusal of literature on (semiconductor) cluster calculations carried out 30 years ago would be useful.

  17. Physics of semiconductor devices

    CERN Document Server

    Rudan, Massimo


    This book describes the basic physics of semiconductors, including the hierarchy of transport models, and connects the theory with the functioning of actual semiconductor devices.  Details are worked out carefully and derived from the basic physics, while keeping the internal coherence of the concepts and explaining various levels of approximation. Examples are based on silicon due to its industrial importance. Several chapters are included that provide the reader with the quantum-mechanical concepts necessary for understanding the transport properties of crystals. The behavior of crystals incorporating a position-dependent impurity distribution is described, and the different hierarchical transport models for semiconductor devices are derived (from the Boltzmann transport equation to the hydrodynamic and drift-diffusion models). The transport models are then applied to a detailed description of the main semiconductor-device architectures (bipolar, MOS). The final chapters are devoted to the description of s...

  18. Biggest semiconductor installed

    CERN Multimedia


    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  19. Electrowetting on a semiconductor


    Arscott, Steve; Gaudet, Matthieu


    We report electrowetting on a semiconductor using of a mercury droplet resting on a silicon surface. The effect is demonstrated using commercial n-type and p-type single-crystal (100) silicon wafers of different doping levels. The electrowetting is reversible - the voltage-dependent wetting contact angle variation of the mercury droplet is observed to depend on both the underlying semiconductor doping density and type. The electrowetting behaviour is explained by the voltage-dependent modulat...

  20. Radiation effects in semiconductors

    CERN Document Server


    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  1. Efficient analysis of mode profiles in elliptical microcavity using dynamic-thermal electron-quantum medium FDTD method. (United States)

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


    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.

  2. High sensitive temperature sensor based on a polymer waveguide integrated in an optical fibre micro-cavity (United States)

    Liu, Yi; Li, Min; Zhao, Panjuan; Wang, Xinshun; Qu, Shiliang


    A Mach–Zehnder interferometer (MZI) based on a polymer waveguide integrated in an optical fibre micro-cavity was proposed. The micro-cavity with two symmetric openings was fabricated in single mode fibre by using femtosecond laser micromachining and fibre splicing. Then, the polymer waveguide with a length of 70 μm was integrated into the micro-cavity by using a two-photon polymerization fabrication method. The MZI exhibited a perfect interference spectrum with a fringe visibility of almost 25 dB. Owing to the high thermo-optical coefficient of the polymer material, the temperature sensitivity of the proposed MZI reached 447 pm/°C. Meanwhile, it can be used as a reliable temperature sensor as its perfect linearity (99.7%) and repeatability.

  3. Tuning refractive index sensing properties of micro-cavity in-line Mach-Zehnder interferometer with plasma etching (United States)

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


    This work presents an application of reactive ion etching (RIE) for an effective tuning of the spectral response and the refractive-index (RI) sensitivity of the micro-cavity in-line Mach-Zehnder interferometer (μIMZI). The μIMZIs were fabricated using femtosecond laser micromachining in a standard single-mode fiber as a form circular holes with a diameter of 54 μm. The application of RIE with SF6 and O2 used as reactive gas allows for an efficient and well controlled etching of the fabricated structure. The process resulted in cleaning the bottom of the micro-cavity and smoothening of its sidewalls. In transmission measurements, the effect of the plasma processing was observed as an increase in both spectral depths of the minima and RI sensitivity of the structure, as well as improved wettability of the micro-cavity surface, which made the measurements faster and easier.

  4. Pine Ridge Fire summary report (United States)

    Hannah Brenkert-Smith; Sarah McCaffrey; Melanie. Stidham


    In July 2012, immediately after the Pine Ridge Fire burned outside De Beque, Colorado, a team of researchers interviewed fire managers, local government officials, and residents to understand perceptions of the event itself, communication, evacuation, and pre-fire preparedness in order to identify contributors to success and areas for improvement. Although the fire had...

  5. Ridge Regression for Interactive Models. (United States)

    Tate, Richard L.


    An exploratory study of the value of ridge regression for interactive models is reported. Assuming that the linear terms in a simple interactive model are centered to eliminate non-essential multicollinearity, a variety of common models, representing both ordinal and disordinal interactions, are shown to have "orientations" that are…

  6. The beach ridges of India: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Kunte, P.D.; Wagle, B.G.

    An attempt has been made to assemble and synthesize research work conducted on beach ridges and associated geomorphic features around India. Information on location, morphology, origin, and age of beach ridges, has been gathered from the literature...

  7. Oak Ridge Leadership Computing Facility (OLCF) (United States)

    Federal Laboratory Consortium — The Oak Ridge Leadership Computing Facility (OLCF) was established at Oak Ridge National Laboratory in 2004 with the mission of standing up a supercomputer 100 times...

  8. InRidge program: Preliminary results from the first cruise

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Murthy, K.S.R.; Iyer, S.D.; Rao, M.M.M.; Banerjee, R.; Subrahmanyam, A.S.; Shirodkar, P.V.; Ghose, I.

    The first cruise under India's own Ridge research initiative, InRidge collected new data on bathymetry, free-air gravity and magnetic anomalies across the ridge axis between the Vema and Zhivago transform faults in the Central Indian Ridge...

  9. Multimode lasing from the microcavity of an octagonal quasi-crystal based on holographic polymer-dispersed liquid crystals. (United States)

    Li, Ming Shian; Fuh, Andy Ying-Guey; Wu, Shing-Trong


    An eightfold photonic quasi-crystal (PQC) sample is fabricated holographically using two-beam interference with multi-exposure based on polymer-dispersed liquid crystals. The transmission spectra from the finite-difference time-domain (FDTD) simulation prove the photonic stop band of the rotational symmetry structure of the sample. The resonant mode of the circular microcavity formed in the PQC is calculated. Amplified spontaneous emission and multimode lasing action are demonstrated from the pumped laser-dye-doped PQC microcavity using a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) pulse laser.

  10. Electrochemically Triggered Release of Reagent to the Proximal Leaflet of a Microcavity Supported Lipid Bilayer. (United States)

    Basit, H; Maher, S; Forster, R J; Keyes, T E


    A novel and versatile approach to electrichemically triggering the release of a reagent, β-cyclodextrin (β-CD), selectively to the proximal leaflet of a supported lipid bilayer is described. Selective delivery is achieved by creating a spanning lipid bilayer across a microcavity array and exploiting the irreversible redox disassembly of the host-guest complex formed between thiolated ferrocene (Fc) and β-cyclodextrin (β-CD) in the presence of chloride. Self-assembled monolayers of the ferrocene-alkanethiols were formed regioselectively on the interior surface of highly ordered 2.8 μm cavities while the exterior top surface of the array was blocked with a monolayer of mercaptoethanol. The Fc monolayers were complexed with β-CD or β-CD-conjugated to streptavidin (β-CD-SA). Phospholipid bilayers were then assembled across the array via combined Langmuir-Blodgett/vesicle fusion leading to a spanning bilayer suspended across the aqueous filled microcavities. Upon application of a positive potential, ferrocene is oxidized to ferrocinium cation, disrupting the inclusion complex and leading to the release of the β-CD into the microcavity solution where it diffuses to the lower leaflet of the suspended bilayer. Disassembly of the supramolecular complex within the cavities and binding of the β-CD-SA to a biotinylated bilayer was followed by voltammetry and impedance spectroscopy where it caused a large increase in membrane resistance. For unmodified β-CD, the extraction of cholesterol from a cholesterol containing bilayer was evident in a decrease in the bilayer resistance. For the first time, this direct approach to targeted delivery of a reagent to the proximal layer of a lipid bilayer offers the potential to build models of bidirectional signaling (inside-out vs outside-in) in cell membrane model systems.

  11. High power 1060-nm super large vertical cavity semiconductor lasers (United States)

    Tan, Shaoyang; Zhai, Teng; Wang, Wei; Zhang, Ruikang; Lu, Dan; Ji, Chen


    High power single-mode ridge waveguide 1060-nm semiconductor lasers are reported. The lasers consist of compressively strained double InGaAs/GaAs quantum wells and a GaAs/AlGaAs separate confinement vertical structure. A super large vertical optical cavity is employed to have a low internal loss, large optical spot size and low vertical optical divergence angle. The material composition and thickness of waveguide layers and claddings layer are optimized systematically. The active layer is detuned from center of the waveguide and thickness of cladding layers is optimized to guaranty single mode lasing of the large optical cavity. The large vertical cavity laser structure with thickness of 4 μm allows the lasers have a low internal loss of less than 0.6 /cm, a large optical spot size about 1μm and a vertical divergence angle about 20 degree. For lateral optical confinement, a double trench ridge waveguide is employed to maintain single-lateral-mode operation. Based on the optimization, 1.5 W continue wave optical power is achieved for broad area lasers with 1mm longitude cavity length. Narrow stripe ridge waveguide lasers of 1mm cavity length with single mode current and optical power of 700 mA and 340 mW is obtained. Suggestions for further improvements in terms of single mode power and applications of the high power semiconductors are discussed.

  12. Pump Frequency Noise Coupling into a Microcavity by Thermo-optic Locking (United States)


    and V. S. Ilchenko,“Ultimate Q of optical microsphere resonators,” Opt. Lett. 21, 453–455 (1996). 4. D. K. Armani , T. J. Kippenberg , S. M. Spillane... Kippenberg , H. Rokhsari, T. Carmon, A. Scherer, and K. J. Vahala, “Analysis of Radiation-Pressure Induced Mechanical Oscillation of an Optical Microcavity...Phys. Rev. Lett. 95, 033901, (2005). 10. T. J. Kippenberg , and K. J. Vahala, “Cavity Optomechanics: Back-Action at the Mesoscale,” Science 321, 1172

  13. Topology optimization of multi-track ring resonators and 2D microcavities for nonlinear frequency conversion (United States)

    Lin, Zin; Lončar, Marko; Rodriguez, Alejandro W.


    We exploit recently developed topology-optimization techniques to design complex, wavelength-scale resonators for enhancing various nonlinear $\\chi^{(2)}$ and $\\chi^{(3)}$ frequency conversion processes. In particular, we demonstrate aperiodic, multi-track ring resonators and 2D slab microcavities exhibiting long lifetimes $Q \\gtrsim 10^4$, small modal volumes $V \\gtrsim (\\lambda/2n)^3$, and among the largest nonlinear overlaps (a generalization of phase matching in large-etalon waveguides) possible, paving the way for efficient, compact, and wide-bandwdith integrated nonlinear devices.

  14. Matrix metalloproteinase sensing via porous silicon microcavity devices functionalized with human antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Marta; Gergely, Csilla [GES-UMR 5650, CNRS, Universite Montpellier 2, Pl. Eugene Bataillon 34095, Montpellier Cedex 5 (France); Taleb Bendiab, Chakib; Massif, Laurent; Cuisinier, Frederic [EA4203, Faculte d' Odontologie, Universite Montpellier 1, Montpellier Cedex 5 (France); Palestino, Gabriela [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Salvador Nava 6, 78000 San Luis Potosi (Mexico); Agarwal, Vivechana [CIICAP, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col Chamilpa, Cuernavaca, Mor. (Mexico)


    Porous silicon microcavity (PSiMc) structures were used as support material for specific sensing of matrix metalloproteinases (MMPs). For lower concentrations of MMP-8, the structures were tested with two types of functionalization methods. Silanization of the oxidized porous silicon structures, followed by glutaraldehyde chemistry was found to give very inconsistent results. The use of biotinilated bovine serum albumin linked to the naked PSiMc was found to be an alternative method to attach the anti MMP-8 human antibody, previously modified with streptavidin, which was further used to sense MMP-8 (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  16. Microcavity quantum-dot systems for non-equilibrium Bose-Einstein condensation

    Energy Technology Data Exchange (ETDEWEB)

    Piper, I M; Ediger, M; Wilson, A M; Wu, Y; Phillips, R T [Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Eastham, P R [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Hugues, M; Hopkinson, M, E-mail: [Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)


    We review the practical conditions required to achieve a non-equilibrium BEC driven by quantum dynamics in a system comprising a microcavity field mode and a distribution of localised two-level systems driven to a step-like population inversion profile. A candidate system based on eight 3.8nm layers of In{sub 0.23}Ga{sub 0.77}As in GaAs shows promising characteristics with regard to the total dipole strength which can be coupled to the field mode.

  17. Topology optimization of multi-track ring resonators and 2D microcavities for nonlinear frequency conversion. (United States)

    Lin, Zin; Lončar, Marko; Rodriguez, Alejandro W


    We exploit recently developed topology-optimization techniques to design complex, wavelength-scale resonators for enhancing various nonlinear χ(2) and χ(3) frequency conversion processes. In particular, we demonstrate aperiodic, multi-track ring resonators and two-dimensional slab microcavities exhibiting long lifetimes Q≳104, small modal volumes V≳(λ/2n)3, and among the largest nonlinear overlaps (a generalization of phase matching in large-etalon waveguides) possible, paving the way for efficient, compact, and wide-bandwdith integrated nonlinear devices.

  18. Selective excitation of laser modes in an organic photonic dot microcavity (United States)

    Langner, M.; Sudzius, M.; Fröb, H.; Lyssenko, V. G.; Leo, K.


    We experimentally investigate variable laser mode excitation in an organic photonic dot microcavity by shifting the excitation beam position. The sample comprises two highly reflective dielectric mirrors (R >99.9%) and a square-shaped organic dye mesa of a DCM doped (2 wt %) Alq3-matrix. Its wavelength-size (≈5×5 μm2) transforms the cavity mode dispersion to a set of discrete states, each with a different intensity distribution of the electromagnetic field in space. Numerical simulations, including absorption and gain, confirm the experimentally observed relation between mode distribution and progression on the excitation condition.

  19. Ultrasensitive detection of cell lysing in an microfabricated semiconductor laser cavity

    Energy Technology Data Exchange (ETDEWEB)

    Gourley, P.L.; French, T.; McDonald, A.E.; Shields, E.A. [Sandia National Labs., Albuquerque, NM (United States); Gourley, M.F. [Washington Hospital Center, Washington, DC (United States)


    In this paper the authors report investigations of semiconductor laser microcavities for use in detecting changes of human blood cells during lysing. By studying the spectra before and during mixing of blood fluids with de-ionized water, they are able to quantify the cell shape and concentration of hemoglobin in real time during the dynamical process of lysing. The authors find that the spectra can detect subtle changes that are orders of magnitude smaller than can be observed by standard optical microscopy. Such sensitivity in observing cell structural changes has implications for measuring cell fragility, monitoring apoptotic events in real time, development of photosensitizers for photodynamic therapy, and in-vitro cell micromanipulation techniques.

  20. Sex Determination from Fingerprint Ridge Density

    Directory of Open Access Journals (Sweden)

    Dr. Sudesh Gungadin


    Full Text Available This study was conducted with an aim to establish a relationship between sex and fingerprint ridge density. The fingerprints were taken from 500 subjects (250 males and 250 females in the age group of 18-60 years. After taking fingerprints, the ridges were counted in the upper portion of the radial border of each print for all ten fingers and mean value was calculated. The results have shown that a finger print ridge of 14 ridges/25 mm2 is more likely of female origin. It has been successful to support the hypothesis that women tend to have a statistically significant greater ridge density than men.

  1. Status of Blue Ridge Reservoir

    Energy Technology Data Exchange (ETDEWEB)


    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Blue Ridge Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports and data available, as well as interview with water resource professionals in various federal, state, and local agencies. Blue Ridge Reservoir is a single-purpose hydropower generating project. When consistent with this primary objective, the reservoir is also operated to benefit secondary objectives including water quality, recreation, fish and aquatic habitat, development of shoreline, aesthetic quality, and other public and private uses that support overall regional economic growth and development. 8 refs., 1 fig.

  2. Oak Ridge National Laboratory Review

    Energy Technology Data Exchange (ETDEWEB)

    Krause, C.; Pearce, J.; Zucker, A. (eds.)


    This report presents brief descriptions of the following programs at Oak Ridge National Laboratory: The effects of pollution and climate change on forests; automation to improve the safety and efficiency of rearming battle tanks; new technologies for DNA sequencing; ORNL probes the human genome; ORNL as a supercomputer research center; paving the way to superconcrete made with polystyrene; a new look at supercritical water used in waste treatment; and small mammals as environmental monitors.

  3. Bose enhancement and the ridge

    Energy Technology Data Exchange (ETDEWEB)

    Altinoluk, Tolga [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia (Spain); Armesto, Néstor, E-mail: [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia (Spain); Beuf, Guillaume [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269-3046 (United States); Lublinsky, Michael [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel)


    We point out that Bose enhancement in a hadronic wave function generically leads to correlations between produced particles. We show explicitly, by calculating the projectile density matrix in the Color Glass Condensate approach to high-energy hadronic collisions, that the Bose enhancement of gluons in the projectile leads to azimuthal collimation of long range rapidity correlations of the produced particles, the so-called ridge correlations.

  4. Bose enhancement and the ridge

    Directory of Open Access Journals (Sweden)

    Tolga Altinoluk


    Full Text Available We point out that Bose enhancement in a hadronic wave function generically leads to correlations between produced particles. We show explicitly, by calculating the projectile density matrix in the Color Glass Condensate approach to high-energy hadronic collisions, that the Bose enhancement of gluons in the projectile leads to azimuthal collimation of long range rapidity correlations of the produced particles, the so-called ridge correlations.

  5. Hydrogen in semiconductors II

    CERN Document Server

    Nickel, Norbert H; Weber, Eicke R; Nickel, Norbert H


    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition ...

  6. Basic Semiconductor Physics

    CERN Document Server

    Hamaguchi, Chihiro


    This book presents a detailed description of the basic semiconductor physics. The reader is assumed to have a basic command of mathematics and some elementary knowledge of solid state physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. The reader can understand three different methods of energy band calculations, empirical pseudo-potential, k.p perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for full band Monte Carlo simulation are discussed. Experiments and theoretical analysis of cyclotron resonance are discussed in detail because the results are essential to the understanding of semiconductor physics. Optical and transport properties, magneto-transport, two dimensional electron gas transport (HEMT and MOSFET), and quantum transport are reviewed, explaining optical transition, electron phonon interactions, electron mob...

  7. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro


    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  8. Large and well-defined Rabi splitting in a semiconductor nanogap cavity. (United States)

    Uemoto, Mitsuharu; Ajiki, Hiroshi


    We propose a nanogap structure composed of semiconductor nanoparticles forming an optical cavity. The resonant excitation of excitons in the nanoparticles can generate a localized strong light field in the gap region, also called "hot spot". The spectral width of the hot spot is significantly narrow because of the small exciton damping and the dephasing at low temperature, so the semiconductor nanogap structure acts as a high-Q cavity. In addition, the interaction between light and matter at the nanogap is significantly larger than that in a conventional microcavity, because the former has a small cavity-mode volume beyond the diffraction limit. We theoretically demonstrate the large and well-defined vacuum-Rabi splitting of a two-level emitter placed inside the semiconductor nanogap cavity: the Rabi splitting energy of 1.7 meV for the transition dipole moment of the emitter (25 Debye) is about 6.3 times larger than the spectral width. An optical cavity providing such a large and well-defined Rabi splitting is highly suited for studying characteristic features of the cavity quantum electrodynamics and for the development of new applications.

  9. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip


    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  10. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B


    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  11. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg


    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  12. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R


    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  13. Optical processes in semiconductors

    CERN Document Server

    Pankove, Jacques I


    Based on a series of lectures at Berkeley, 1968-1969, this is the first book to deal comprehensively with all of the phenomena involving light in semiconductors. The author has combined, for the graduate student and researcher, a great variety of source material, journal research, and many years of experimental research, adding new insights published for the first time in this book.Coverage includes energy states in semiconductors and their perturbation by external parameters, absorption, relationships between optical constants, spectroscopy, radiative transitions, nonradiative recombination

  14. Growth of photovoltaic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. (Bell Communications Research, Red Bank, NJ (United States)); Stringfellow, G.B. (Univ. of Utah, Salt Lake City (United States)); Greene, J.E. (Univ. of Illinois, Urbana (United States))


    We assess the opportunities for improving the quality and lowering the cost of thin crystalline semiconductor films for photovoltaics. We find that novel growth and processing methods can lower the cost of crystalline semiconductor films to satisfy the economic conditions for a major expansion of the photovoltaic industry. The research requirements are in the areas of novel precursors for vapor phase growth, atomic layer epitaxy for unprecedented control, and the requirement for novel in situ and ex situ probes to ensure that the new growth methods are producing the utmost in photovoltaic material quality. 42 refs.

  15. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati


    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  16. Efficient micro-cavity top emission OLED with optimized Mg:Ag ratio cathode. (United States)

    Kwon, Sun-Kap; Lee, Eun-Hyung; Kim, Kwan-Soo; Choi, Hyun-Chul; Park, Mi Jin; Kim, Seong Keun; Pode, Ramchandra; Kwon, Jang Hyuk


    Micro-cavity top-emitting organic light emitting diodes (TEOLEDs) are now receiving prominence as a technology for the active matrix display applications. The semi-transparent metal cathode plays the crucial role in realizing TEOLEDs structure. Here, we report the optimization results on Mg:Ag ratio as the semitransparent cathode deposited by vacuum thermal evaporation. The optimized Mg:Ag cathode with 1:10 ratio (wt %) shows a sheet resistance value as low as 5.2 Ω/□, an average transmittance of 49.7%, reflectance of 41.4%, and absorbance of 8.9% over the visible spectral region (400~700 nm). The fabricated red TEOLEDs device implemented using LiF (1nm)/Mg:Ag (1:10) cathode shows the voltage value of 4.17 V at a current density of 10.00 mA/cm2, and current efficiencies variation from 55.3 to 50.1 cd/A over the brightness range 2,000 - 12,000 cd/m2. The electroluminescence (EL) spectrum displays the light emission at 608 nm wavelength with a half width of 29.5 nm. The narrow half-width of red light emission is attributed to the micro-cavity effects due to the semitransparent cathode.

  17. The Detection of Helicobacter hepaticus Using Whispering-Gallery Mode Microcavity Optical Sensors. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Mark E. Anderson


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

  19. Light–matter interaction in a microcavity-controlled graphene transistor (United States)

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


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

  20. Modelling Laser Milling of Microcavities for the Manufacturing of DES with Ensembles

    Directory of Open Access Journals (Sweden)

    Pedro Santos


    Full Text Available A set of designed experiments, involving the use of a pulsed Nd:YAG laser system milling 316L Stainless Steel, serve to study the laser-milling process of microcavities in the manufacture of drug-eluting stents (DES. Diameter, depth, and volume error are considered to be optimized as functions of the process parameters, which include laser intensity, pulse frequency, and scanning speed. Two different DES shapes are studied that combine semispheres and cylinders. Process inputs and outputs are defined by considering the process parameters that can be changed under industrial conditions and the industrial requirements of this manufacturing process. In total, 162 different conditions are tested in a process that is modeled with the following state-of-the-art data-mining regression techniques: Support Vector Regression, Ensembles, Artificial Neural Networks, Linear Regression, and Nearest Neighbor Regression. Ensemble regression emerged as the most suitable technique for studying this industrial problem. Specifically, Iterated Bagging ensembles with unpruned model trees outperformed the other methods in the tests. This method can predict the geometrical dimensions of the machined microcavities with relative errors related to the main average value in the range of 3 to 23%, which are considered very accurate predictions, in view of the characteristics of this innovative industrial task.

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

    Directory of Open Access Journals (Sweden)

    Zengling Ran


    Full Text Available 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.

  2. Photonic lattices in organic microcavities: Bloch states and control of lasing (United States)

    Mischok, Andreas; Brückner, Robert; Fröb, Hartmut; Lyssenko, Vadim G.; Leo, Karl


    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.

  3. Thermo-optical interactions in a dye-microcavity photon Bose–Einstein condensate (United States)

    Alaeian, Hadiseh; Schedensack, Mira; Bartels, Clara; Peterseim, Daniel; Weitz, Martin


    Superfluidity and Bose–Einstein condensation are usually considered as two closely related phenomena. Indeed, in most macroscopic quantum systems, like liquid helium, ultracold atomic Bose gases, and exciton-polaritons, condensation and superfluidity occur in parallel. In photon Bose–Einstein condensates realized in the dye microcavity system, thermalization does not occur by direct interaction of the condensate particles as in the above described systems, i.e. photon–photon interactions, but by absorption and re-emission processes on the dye molecules, which act as a heat reservoir. Currently, there is no experimental evidence for superfluidity in the dye microcavity system, though effective photon interactions have been observed from thermo-optic effects in the dye medium. In this work, we theoretically investigate the implications of effective thermo-optic photon interactions, a temporally delayed and spatially non-local effect, on the photon condensate, and derive the resulting Bogoliubov excitation spectrum. The calculations suggest a linear photon dispersion at low momenta, fulfilling the Landau’s criterion of superfluidity. We envision that the temporally delayed and long-range nature of the thermo-optic photon interaction offer perspectives for novel quantum fluid phenomena.

  4. Advances in optoplasmonic sensors – combining optical nano/microcavities and photonic crystals with plasmonic nanostructures and nanoparticles

    Directory of Open Access Journals (Sweden)

    Xavier Jolly


    Full Text Available Nanophotonic device building blocks, such as optical nano/microcavities and plasmonic nanostructures, lie at the forefront of sensing and spectrometry of trace biological and chemical substances. A new class of nanophotonic architecture has emerged by combining optically resonant dielectric nano/microcavities with plasmonically resonant metal nanostructures to enable detection at the nanoscale with extraordinary sensitivity. Initial demonstrations include single-molecule detection and even single-ion sensing. The coupled photonic-plasmonic resonator system promises a leap forward in the nanoscale analysis of physical, chemical, and biological entities. These optoplasmonic sensor structures could be the centrepiece of miniaturised analytical laboratories, on a chip, with detection capabilities that are beyond the current state of the art. In this paper, we review this burgeoning field of optoplasmonic biosensors. We first focus on the state of the art in nanoplasmonic sensor structures, high quality factor optical microcavities, and photonic crystals separately before proceeding to an outline of the most recent advances in hybrid sensor systems. We discuss the physics of this modality in brief and each of its underlying parts, then the prospects as well as challenges when integrating dielectric nano/microcavities with metal nanostructures. In Section 5, we hint to possible future applications of optoplasmonic sensing platforms which offer many degrees of freedom towards biomedical diagnostics at the level of single molecules.

  5. Advances in optoplasmonic sensors - combining optical nano/microcavities and photonic crystals with plasmonic nanostructures and nanoparticles (United States)

    Xavier, Jolly; Vincent, Serge; Meder, Fabian; Vollmer, Frank


    Nanophotonic device building blocks, such as optical nano/microcavities and plasmonic nanostructures, lie at the forefront of sensing and spectrometry of trace biological and chemical substances. A new class of nanophotonic architecture has emerged by combining optically resonant dielectric nano/microcavities with plasmonically resonant metal nanostructures to enable detection at the nanoscale with extraordinary sensitivity. Initial demonstrations include single-molecule detection and even single-ion sensing. The coupled photonic-plasmonic resonator system promises a leap forward in the nanoscale analysis of physical, chemical, and biological entities. These optoplasmonic sensor structures could be the centrepiece of miniaturised analytical laboratories, on a chip, with detection capabilities that are beyond the current state of the art. In this paper, we review this burgeoning field of optoplasmonic biosensors. We first focus on the state of the art in nanoplasmonic sensor structures, high quality factor optical microcavities, and photonic crystals separately before proceeding to an outline of the most recent advances in hybrid sensor systems. We discuss the physics of this modality in brief and each of its underlying parts, then the prospects as well as challenges when integrating dielectric nano/microcavities with metal nanostructures. In Section 5, we hint to possible future applications of optoplasmonic sensing platforms which offer many degrees of freedom towards biomedical diagnostics at the level of single molecules.

  6. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G


    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  7. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah


    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  8. Changing characteristics of arctic pressure ridges (United States)

    Wadhams, Peter; Toberg, Nick


    The advent of multibeam sonar permits us to obtain full three-dimensional maps of the underside of sea ice. In particular this enables us to distinguish the morphological characteristics of first-year (FY) and multi-year (MY) pressure ridges in a statistically valid way, whereas in the past only a small number of ridges could be mapped laboriously by drilling. In this study pressure ridge distributions from two parts of the Arctic Ocean are compared, in both the cases using mainly data collected by the submarine “Tireless” in March 2007 during two specific grid surveys, in the Beaufort Sea at about 75° N, 140° W (N of Prudhoe Bay), and north of Ellesmere Island at about 83° 20‧ N, 64° W. In the Beaufort Sea the ice was mainly FY, and later melted or broke up as this area became ice-free during the subsequent summer. N of Ellesmere Island the ice was mainly MY. Ridge depth and spacing distributions were derived for each region using the boat's upward looking sonar, combined with distributions of shapes of the ridges encountered, using the Kongsberg EM3002 multibeam sonar. The differing shapes of FY and MY ridges are consistent with two later high-resolution multibeam studies of specific ridges by AUV. FY ridges are found to fit the normal triangular shape template in cross-section (with a range of slope angles averaging 27°) with a relatively constant along-crest depth, and often a structure of small ice blocks can be distinguished. MY ridges, however, are often split into a number of independent solid, smooth blocks of large size, giving an irregular ridge profile which may be seemingly without linearity. Our hypothesis for this difference is that during its long lifetime an MY ridge is subjected to several episodes of crack opening; new cracks in the Arctic pack often run in straight lines across the ridges and undeformed ice alike. Such a crack will open somewhat before refreezing, interpolating a stretch of thin ice into the structure, and breaking up

  9. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias


    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz nonlinear......In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... is determined by (but not equal to) the electron momentum relaxation rate. Single cycle pulses of light, irrespective of the frequency range to which they belong, inherently have an ultrabroadband spectrum covering many octaves of frequencies. Unlike the single-cycle pulses in optical domain, the THz pulses can...... be easily sampled with sub-cycle resolution using conventional femtosecond lasers. This makes the THz pulses accessible model tools for direct observation of general nonlinear optical phenomena occurring in the single-cycle regime....

  10. Physics of semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Prew, B.A.


    The properties of semiconductors which make them important in the electronic devices industry, and how these properties are controlled by doping, are described. The physics and applications of p-n and other junction devices, and of bulk effect devices are discussed. Avalanche devices, optical devices, solar cells, Schottky barriers, MOS devices, heterojunctions, photoconductors, and transferred electron devices are considered.

  11. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    11] A detailed review article of defects in semiconductor nanostructures is currently under preparation. [12] V Ranjan and Vijay A Singh, J. Appl. Phys. 89, 6415 (2001). [13] V Ranjan, R K Pandey, Manoj K Harbola and Vijay A Singh, Phys. Rev.

  12. An Evaluation of Ridge Regression. (United States)


    of the parameter estimates, is a decreasing function of k. The idea of ridge regression, as suggested by Hoerl and Kennard (Ref 12:58-63), is to pick...CROSS? 0 CR0553 f.812 CR0554 0 CR0555 4.39? CROSS6 0 ALSO 4.922 KSO 0 NVARSO 4. A5059 .622 CONTFNTS OF CASE NUlIPER 209 SEQHUI 209. SUOILE PEGANAL CASWGT...KSQ .000 NVARSO 9. RSOSO .846 CONTENTS OF CASE NUMBER 55 SEONUN 55. SUfTFILE PEGANAL CASWGI 2.0000 459 .970 RI 76600 K .025 NVA? 3. MSE .177 NS[IS

  13. Pendeteksian Outlier dengan Metode Regresi Ridge

    Directory of Open Access Journals (Sweden)

    Sri Harini


    Full Text Available Dalam analisis regresi linier berganda adanya satu atau lebih pengamatan pencilan (outlier akan menimbulkan dilema bagi para peneliti. Keputusan untuk menghilangkan pencilan tersebut harus dilandasi alasan yang kuat, karena kadang-kadang pencilan dapat memberikan informasi penting yang diperlukan. Masalah outlier ini dapat diatasi dengan berbagai metode, diantaranya metode regresi ridge (ridge regression. Untuk mengetahui kekekaran regresi ridge perlu melihat nilai-nilai R2, PRESS, serta leverage (hii, untuk metode regresi ridge dengan berbagai nilai tetapan bias k yang dipilih.

  14. Large fault fabric of the Ninetyeast Ridge implies near-spreading ridge formation

    Digital Repository Service at National Institute of Oceanography (India)

    Sager, W.W.; Paul, C.F.; Krishna, K.S.; Pringle, M.S.; Eisin, A.E.; Frey, F.A.; Rao, D.G.; Levchenko, O.V.

    Ninetyeast Ridge (NER) is a linear volcanic ridge in the Indian Ocean thought to have formed by hotspot volcanism on the northward?drifting Indian plate. Geological data from the ridge are sparse, so its tectonic evolution is poorly known. We...

  15. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro


    This book presents a detailed description of basic semiconductor physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. Four different methods of energy band calculations in the full band region are explained: local empirical pseudopotential, non-local pseudopotential, KP perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for analysis of transport properties are discussed. Further, the book examines experiments and theoretical analyses of cyclotron resonance in detail. Optical and transport properties, magneto-transport, two-dimensional electron gas transport (HEMT and MOSFET) and quantum transport are reviewed, while optical transition, electron-phonon interaction and electron mobility are also addressed. Energy and electronic structure of a quantum dot (artificial atom) are explained with the help of Slater determinants. The...

  16. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert


    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  17. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui


    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  18. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz


    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  19. Infrared Semiconductor Metamaterials (United States)


    AFRL-AFOSR-VA-TR-2016-0310 Infrared Semiconductor Metamaterials Jon Schuller UNIVERSITY OF CALIFORNIA SANTA BARBARA 3227 CHEADLE HL SANTA BARBARA, CA...S) AND ADDRESS(ES) University of California , Santa Barbara Office of Research, 3227 Cheadle Hall Santa Barbara, CA 93106-2050 8. PERFORMING...Using Heterojunction Resonators. Advanced Optical Materials, available online (2016). New discoveries, inventions, or patent disclosures: Do you have

  20. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN


    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  1. Hole crystallization in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bonitz, M [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Filinov, V S [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Fortov, V E [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Levashov, P R [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Fehske, H [Institut fuer Physik, Universitaet Greifswald, l7487 Greifswald (Germany)


    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  2. Hole crystallization in semiconductors


    Bonitz, M.; Filinov, V. S.; Fortov, V. E.; Levashov, P. R.; Fehske, H.


    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  3. Mass and Momentum Transport in Microcavities for Diffusion-Dominant Cell Culture Applications (United States)

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


    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.

  4. Entropic Lattice Boltzmann study of hydrodynamics in a microcavity - Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Karlin, I. V.; Ansumali, S.; Frouzakis, Ch. E.; Boulouchos, K. [Eidgenoessische Technische Hochschule (ETH), Labor fuer Aerothermochemie und Verbrennungssysteme ETHZ, ETH-Zentrum, Zuerich (Switzerland)


    This yearly report for 2004 presents a review of work being done on behalf of the Swiss Federal Office of Energy (SFOE) at the Laboratory for Aero-thermochemistry and Combustion Systems at the Federal Institute of Technology ETH in Zurich, Switzerland, on the development of a new approximation method for use in micrometer-scale flow calculations. The method, based on recently-developed so-called minimal entropy-kinetic models of the Boltzmann-kinetic equation, is discussed. Two detailed studies of micro-flows in specific geometries are discussed. The potential of the new method as a replacement for costly microscopic simulation methods is examined. The development and testing of a new thermal model - the so-called Thermal D2Q9 model - is discussed. A second study examined flows in a micro-cavity. A detailed parametric study of the quantitative and qualitative properties of the flows for a comprehensive range of dilution is mentioned.

  5. On-Chip High-Finesse Fabry-Perot Microcavities for Optical Sensing and Quantum Information

    Directory of Open Access Journals (Sweden)

    Mohammad H. Bitarafan


    Full Text Available For applications in sensing and cavity-based quantum computing and metrology, open-access Fabry-Perot cavities—with an air or vacuum gap between a pair of high reflectance mirrors—offer important advantages compared to other types of microcavities. For example, they are inherently tunable using MEMS-based actuation strategies, and they enable atomic emitters or target analytes to be located at high field regions of the optical mode. Integration of curved-mirror Fabry-Perot cavities on chips containing electronic, optoelectronic, and optomechanical elements is a topic of emerging importance. Micro-fabrication techniques can be used to create mirrors with small radius-of-curvature, which is a prerequisite for cavities to support stable, small-volume modes. We review recent progress towards chip-based implementation of such cavities, and highlight their potential to address applications in sensing and cavity quantum electrodynamics.

  6. Rolled-up TiO₂ optical microcavities for telecom and visible photonics. (United States)

    Madani, Abbas; Böttner, Stefan; Jorgensen, Matthew R; Schmidt, Oliver G


    The fabrication of high-quality-factor polycrystalline TiO₂ vertically rolled-up microcavities (VRUMs) by the controlled release of differentially strained TiO₂ bilayered nanomembranes, operating at both telecom and visible wavelengths, is reported. Optical characterization of these resonators reveals quality factors as high as 3.8×10³ in the telecom wavelength range (1520-1570 nm) by interfacing a TiO₂ VRUMs with a tapered optical fiber. In addition, a splitting in the fundamental modes is experimentally observed due to the broken rotational symmetry in our resonators. This mode splitting indicates coupling between clockwise and counterclockwise traveling whispering gallery modes of the VRUMs. Moreover, we show that our biocompatible rolled-up TiO₂ resonators function at several positions along the tube, making them promising candidates for multiplexing and biosensing applications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mazzeo, M., E-mail: [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento, Via Monteroni, 73100 Lecce (Italy); NNL, Istituto Nanoscienze - CNR, Via Arnesano, 73100 Lecce (Italy); Genco, A. [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento, Via Monteroni, 73100 Lecce (Italy); Gambino, S. [NNL, Istituto Nanoscienze - CNR, Via Arnesano, 73100 Lecce (Italy); CBN, Istituto Italiano Tecnologia, Via Barsanti 1, 73010 Lecce (Italy); Ballarini, D.; Mangione, F.; Sanvitto, D. [NNL, Istituto Nanoscienze - CNR, Via Arnesano, 73100 Lecce (Italy); Di Stefano, O.; Patanè, S.; Savasta, S. [Dipartimento di Fisica e Scienze della Terra, Università di Messina, Viale F. Stagno d' Alcontres 31, 98166 Messina (Italy); Gigli, G. [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento, Via Monteroni, 73100 Lecce (Italy); NNL, Istituto Nanoscienze - CNR, Via Arnesano, 73100 Lecce (Italy); CBN, Istituto Italiano Tecnologia, Via Barsanti 1, 73010 Lecce (Italy)


    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.

  8. Ultra-sensitive chemical vapor detection using micro-cavity photothermal spectroscopy. (United States)

    Hu, Juejun


    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.

  9. Hybrid quantum gates between flying photon and diamond nitrogen-vacancy centers assisted by optical microcavities (United States)

    Wei, Hai-Rui; Lu Long, Gui


    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

  10. Room temperature strong coupling effects from single ZnO nanowire microcavity

    KAUST Repository

    Das, Ayan


    Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non-linearity in the polariton emission characteristics is observed at room temperature with a low threshold of 1.63 ?J/cm2, which corresponds to a polariton density an order of magnitude smaller than that for the Mott transition. The momentum distribution of the lower polaritons shows evidence of dynamic condensation and the absence of a relaxation bottleneck. The polariton relaxation dynamics were investigated by timeresolved measurements, which showed a progressive decrease in the polariton relaxation time with increase in polariton density. © 2012 Optical Society of America.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tzimis, A.; Savvidis, P. G. [Department of Materials Science and Technology, University of Crete, 71003 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Trifonov, A. V.; Ignatiev, I. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); Christmann, G.; Tsintzos, S. I. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Hatzopoulos, Z. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, 71003 Heraklion, Crete (Greece); Kavokin, A. V. [Spin Optics Laboratory, State University of Saint-Petersburg, 1 Ulianovskaya, 198504 St. Petersburg (Russian Federation); School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)


    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.

  12. Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy

    CERN Document Server

    Cheema, M Imran; Hayat, Ahmad A; Peter, Yves-Alain; Armani, Andrea M; Kirk, Andrew G


    Optical resonant microcavities with ultra high quality factors are widely used for biosensing. Until now, the primary method of detection has been based upon tracking the resonant wavelength shift as a function of biological events. One of the sources of noise in all resonant-wavelength shift measurements is the noise due to intensity fluctuations of the laser source. An alternative approach is to track the change in the quality factor of the optical cavity by using phase shift cavity ring down spectroscopy, a technique which is insensitive to the intensity fluctuations of the laser source. Here, using biotinylated microtoroid resonant cavities, we show simultaneous measurement of the quality factor and the wavelength shift by using phase shift cavity ring down spectroscopy. These measurements were performed for disassociation phase of biotin-streptavidin reaction. We found that the disassociation curves are in good agreement with the previously published results. Hence, we demonstrate not only the applicatio...

  13. Temperature-induced tuning of emission spectra of liquid-crystal optical microcavities (United States)

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


    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.

  14. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W


    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  15. Petrology of tectonically segmented Central Indian Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Iyer, S.D.

    Distribution and mineralogy of various rock types along the 4200-km-long slow-spreading Central Indian Ridge, between Owen fracture zone in the north and Indian Ocean triple junction in the south, is studied in the light of ridge segmentation...

  16. Pulley Ridge Swath Bathymetry Grid - filtered (United States)

    U.S. Geological Survey, Department of the Interior — Pulley Ridge is a series of drowned barrier islands that extends almost 200 km in 60-100 m water depths. This drowned ridge is located on the Florida Platform in the...

  17. An identity for kernel ridge regression


    Zhdanov, Fedor; Kalnishkan, Yuri


    This paper derives an identity connecting the square loss of ridge regression in on-line mode with the loss of the retrospectively best regressor. Some corollaries about the properties of the cumulative loss of on-line ridge regression are also obtained.

  18. On the ridging of intact lead ice (United States)

    Hopkins, Mark A.


    The sea ice pressure ridging process is modeled using a two-dimensional particle simulation technique. In this model, blocks are broken from an intact sheet of relatively thin lead ice driven against a thick, multiyear floe at a constant speed. The blocks of ice rubble accumulate to form the ridge sail and keel. The energy consumed in ridge growth, including dissipation, is explicitly calculated. A series of numerical experiments are performed to establish the dependence of the energetics on the thickness of the ice sheet and the friction between blocks. The results suggest that the total energy required to create a pressure ridge is an order of magnitude greater than the potential energy in the ridge structure. A typical sea ice cover in the polar regions contains a variety of ice thicknesses that evolve in response to both dynamic and thermodynamic forcing. The variable thickness of the ice cover is created by deformation, which simultaneously causes formation of thick ice through ridge building and thin ice through lead creation. Since the energy expended in deformation is largely determined by the ridging process, an understanding of the energetics of pressure ridging is critical in the determination of ice strength on a geophysical scale.

  19. Sex Determination from Fingerprint Ridge Density | Gungadin ...

    African Journals Online (AJOL)

    This study was conducted with an aim to establish a relationship between sex and fingerprint ridge density. The fingerprints were taken from 500 subjects (250 males and 250 females) in the age group of 18-60 years. After taking fingerprints, the ridges were counted in the upper portion of the radial border of each print for all ...

  20. Manastash Ridge Observatory Autoguider Upgrade (United States)

    Lozo, Jason; Huehnerhoff, Joseph; Armstrong, John; Davila, Adrian; Johnson, Courtney; McMaster, Alex; Olinger, Kyle


    The Astronomy Undergraduate Engineering Group (AUEG) at the University of Washington has designed and manufactured a novel autoguider system for the 0.8-meter telescope at the Manastash Ridge Observatory in Ellensburg, Washington. The system uses a pickoff mirror placed in the unused optical path, directing the outer field to the guide camera via a system of axi-symmetrically rotating relay mirrors (periscope). This allows the guider to sample nearly 7 times the area that would be possible with the same fixed detector. This system adds closed loop optical feedback to the tracking capabilities of the telescope. When tuned the telescope will be capable of acheiving 0.5 arcsecond tracking or better. Dynamic focusing of the primary optical path will also be an included feature of this system. This unique guider will be a much needed upgrade to the telescope allowing for increased scientific capability.

  1. Second International Conference on Neutron Transmutation Doping in Semiconductors

    CERN Document Server

    Neutron Transmutation Doping in Semiconductors


    This volume contains the invited and contributed papers presented at the Second International Conference on Neutron Transmutation Doping in Semiconductors held April 23-26, 1978 at the University of Missouri-Columbia. The first "testing of the waters" symposium on this subject was organized by John Cleland and Dick Wood of the Solid-State Division of Oak Ridge National Laboratory in April of 1976, just one year after NTD-silicon appeared on the marketplace. Since this first meeting, NTD-silicon has become established as the starting material for the power device industry and reactor irradiations are now measured in tens of tons of material per annum making NTD processing the largest radiation effects technology in the semiconductor industry. Since the first conference at Oak Ridge, new applications and irradiation techniques have developed. Interest in a second con­ ference and in publishing the proceedings has been extremely high. The second conference at the University of Missouri was attended by 114 perso...

  2. Broad-spectrum enhanced absorption of graphene-molybdenum disulfide photovoltaic cells in Metal-Mirror Microcavity. (United States)

    Liu, Jiang Tao; Cao, Yunkai; Tong, Hong; Wang, Dahai; Wu, Zhenhua


    We investigate theoretically the optical absorption of graphene-molybdenum disulfide photovoltaic cells (GM-PVc) in wedge-shaped metal-mirror microcavities (w-MMCs) combined with spectrum-splitting structure. Results show that the combination of spectrum-splitting structure and w-MMC can enable the light absorption of GM-PVc to reach about 65% in the broad spectrum. The influence of processing errors on the absorption of GM-PVc in w-MMCs is effectively suppressed, i.e., 3 ~14 times lower than that of GM-PVc in common wedge photonic crystal microcavities. The light absorption of GM-PVc reaches 60% in broad spectrum even with the processing errors. This proposal of GM-PVc structure is easy to implement and has potentially important applications in the development of ultra-thin and high-efficiency solar cells and optoelectronic devices. © 2018 IOP Publishing Ltd.

  3. Microcavity-quality-factor enhancement using nonlinear effects close to the bistability threshold and coherent population oscillations (United States)

    Dumeige, Y.; Yacomotti, A. M.; Grinberg, P.; Bencheikh, K.; Le Cren, E.; Levenson, J. A.


    We analytically show that inserting a driven, two-level system inside a microcavity can improve its optical properties. In this approach, the strong dispersion induced by a pump via population oscillations increases the cavity lifetime experienced by a slightly detuned probe. We further predict that if the cavity is pumped through a resonant channel, optical absorptive or dispersive bistability can be combined with the population-oscillation-induced steep material dispersion to obtain a strong quality-factor enhancement. Moreover, differential amplification coming from the nonlinear feature of the pump transfer function can be used to drastically increase the probe transmission beyond intrinsic characteristics of the resonator. The Q-factor enhancement and the differential amplification can be advantageously combined with a frequency pulling effect to stabilize or readjust the microcavity resonance frequency.

  4. Design and characterization of high optical quality InGaAs/GaAs/AlGaAs-based polariton microcavities (United States)

    Tinkler, L.; Walker, P. M.; Clarke, E.; Krizhanovskii, D. N.; Bastiman, F.; Durska, M.; Skolnick, M. S.


    The presence of dislocations arising from strain relaxation strongly affects polaritons through their photonic component and ultimately limits experiments involving polariton propagation. In this work, we investigate the range of growth parameters to achieve high optical quality GaAs/AlxGa1-xAs-based microcavities containing strained InxGa1-xAs quantum wells and using differential interference contrast (Nomarski) microscopy deduce a design rule for homogeneous versus disordered structures. We illustrate the effect of disorder by contrasting observations of polariton condensates in relaxed and unrelaxed microcavities. In our optimized device, we generate a polariton condensate and deduce a lifetime for the interacting polariton fluid of 39 ± 2 ps.

  5. Electrodes for Semiconductor Gas Sensors (United States)

    Lee, Sung Pil


    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

  6. Method of passivating semiconductor surfaces (United States)

    Wanlass, M.W.


    A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  7. Large-scale parallel surface functionalization of goblet-type whispering gallery mode microcavity arrays for biosensing applications. (United States)

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


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

  8. On the physics of semiconductor quantum dots for applications in lasers and quantum optics (United States)

    Chow, Weng W.; Jahnke, Frank


    The progression of carrier confinement from quantum wells to quantum dots has received considerable interests because of the potential to improve the semiconductor laser performance at the underlying physics level and to explore quantum optical phenomena in semiconductors. Associated with the transition from quantum wells to quantum dots is a switch from a solid-state-like quasi-continuous density of states to an atom-like system with discrete states. As discussed in this paper, the transition changes the role of the carrier interaction processes that directly influence optical properties. Our goals in this review are two-fold. One is to identify and describe the physics that allows new applications and determines intrinsic limitations for applications in light emitters. We will analyze the use of quantum dots in conventional laser devices and in microcavity emitters, where cavity quantum electrodynamics can alter spontaneous emission and generate nonclassical light for applications in quantum information technologies. A second goal is to promote a new connection between physics and technology. This paper demonstrates how a first-principles theory may be applied to guide important technological decisions by predicting the performances of various active materials under a broad set of experimental conditions.

  9. Layered semiconductor neutron detectors (United States)

    Mao, Samuel S; Perry, Dale L


    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  10. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I


    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  11. Physics of Organic Semiconductors

    CERN Document Server

    Brütting, Wolfgang


    Filling the gap in the literature currently available, this book presents an overview of our knowledge of the physics behind organic semiconductor devices. Contributions from 18 international research groups cover various aspects of this field, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in such different devices as organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. From the contents:. * Excitation Dynamics in O

  12. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M


    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  13. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT


    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  14. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)


    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  15. Squeezed light in semiconductors

    CERN Document Server

    Ward, M B


    Experimental evidence is presented for the generation of photon-number squeezed states of light as a result of multi-photon absorption. Photon-number squeezing as a result of non-linear absorption has long been predicted and results have been obtained utilising two very different material systems: (i) an AIGaAs waveguide in which high optical intensities can be maintained over a relatively long interaction length of 2 mm; (ii) the organic polymer p-toluene sulphonate polydiacetylene that is essentially a one-dimensional semiconductor possessing a highly nonlinear optical susceptibility. The resulting nonlinear absorption is shown to leave the transmitted light in a state that is clearly nonclassical, exhibiting photon-number fluctuations below the shot-noise limit. Tuning the laser wavelength across the half-bandgap energy has enabled a comparison between two- and three-photon processes in the semiconductor waveguide. The correlations created between different spectral components of a pulsed beam of light as ...

  16. II-VI semiconductor compounds

    CERN Document Server


    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  17. Variable temperature semiconductor film deposition (United States)

    Li, X.; Sheldon, P.


    A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  18. Process for producing chalcogenide semiconductors (United States)

    Noufi, R.; Chen, Y.W.


    A process for producing chalcogenide semiconductor material is disclosed. The process includes forming a base metal layer and then contacting this layer with a solution having a low pH and containing ions from at least one chalcogen to chalcogenize the layer and form the chalcogenide semiconductor material.

  19. Semiconductor materials and their properties

    NARCIS (Netherlands)

    Reinders, Angelina H.M.E.; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre; Reinders, Angele; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre


    Semiconductor materials are the basic materials which are used in photovoltaic (PV) devices. This chapter introduces solid-state physics and semiconductor properties that are relevant to photovoltaics without spending too much time on unnecessary information. Usually atoms in the group of

  20. Semiconductor photocatalysis principles and applications

    CERN Document Server

    Kisch, Horst


    Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

  1. Luminescence studies of semiconductor electrodes

    NARCIS (Netherlands)

    Kelly, J.J.; Kooij, Ernst S.; Meulenkamp, E.A.


    In this paper we review our recent results of in-situ luminescence studies of semiconductor electrodes. Three classes of materials are considered: single crystal compound semiconductors, porous silicon and semiconducting oxides doped with luminescent ions. We show how photoluminescence (PL) and

  2. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I


    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  3. Carlsberg Ridge and Mid-Atlantic Ridge: Comparison of slow spreading centre analogues (United States)

    Murton, Bramley J.; Rona, Peter A.


    Eighty per cent of all mid-ocean spreading centres are slow. Using a mixture of global bathymetry data and ship-board multibeam echosounder data, we explore the morphology of global mid-ocean ridges and compare two slow spreading analogues: the Carlsberg Ridge in the north-west Indian Ocean between 57°E and 60°E, and the Kane to Atlantis super-segment of the Mid-Atlantic Ridge between 21°N and 31°N. At a global scale, mid-ocean spreading centres show an inverse correlation between segment length and spreading rate with segmentation frequency. Within this context, both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge are similar: spreading at 22 and 26 mm/yr full rates respectively, being devoid of major transform faults, and being segmented by dextral, non-transform, second-order discontinuities. For these and other slow spreading ridges, we show that segmentation frequency varies inversely with flank height and ridge axis depth. Segments on both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge range in aspect ratio (ridge flank height/axis width), depth and symmetry. Segments with high aspect ratios and deeper axial floors often have asymmetric rift flanks and are associated with indicators of lower degrees of melt flux. Segments with low aspect ratios have shallower axial floors, symmetric rift flanks, and evidence of robust melt supply. The relationship between segmentation, spreading rate, ridge depth and morphology, at both a global and local scale, is evidence that rates of melting of the underlying mantle and melt delivery to the crust play a significant role in determining the structure and morphology of slow spreading mid-ocean ridges.

  4. Alveolar ridge augmentation by osteoinduction in rats

    DEFF Research Database (Denmark)

    Pinholt, E M; Bang, G; Haanaes, H R


    The purpose of this study was to evaluate bone substitutes for alveolar ridge augmentation by osteoinduction. Allogenic, demineralized, and lyophilized dentin and bone was tested for osteoinductive properties in order to establish an experimental model for further studies. Implantations were...

  5. Petrography of basalts from the Carlsberg ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Iyer, S.D.

    and olivine phenocrysts, in addition to numerous filled and unfilled vesicles. These basalts are of the moderately plagioclase phyric basalts (MPPB) variety and are comparable to those of the Mid-Atlantic Ridge...

  6. High-quality Mach-Zehnder interferometer based on a microcavity in single-multi-single mode fiber structure for refractive index sensing. (United States)

    Liu, Yi; Wu, Guoqiang; Gao, Renxi; Qu, Shiliang


    A fiber inline Mach-Zehnder interferometer (MZI) based on a microcavity with two symmetric openings in single-multi-single mode fiber (SMSF) structure is proposed. By using the finite difference beam propagation method (FD-BPM), the interference spectrum simulation result shows that the MZI can still have high-quality interference even if the microcavity deviates along the radial direction for 3 μm. Therefore, it allows a larger fabrication tolerance and tremendously decreases the fabrication difficulty. Then a microcavity with two symmetric openings in SMSF was fabricated by using femtosecond laser-induced water breakdown. The insertion loss of the microcavity immerged in water is only -8  dB, and the MZ interference peak contrast in the transmission spectrum reaches more than 30 dB. The MZI based on the microcavity in SMSF can be used as a practical liquid refractive index sensor as its high-quality interference spectrum, ultrahigh sensitivity (9756.75 nm/RIU), high refractive index resolution (2×10-5  RIU), good linearity (99.93%), and low-temperature crosstalk (0.04 nm/°C).

  7. Internal Tide Generation by Tall Ocean Ridges (United States)


    dissipation is not phys- ical but illustrates the level of noise in the computation. Reproduced from [20]. The locations of the Hawaiian and Luzon ridges... assembled Foamlinx foam cutter, and (b) photograph while cutting a model ridge. . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 2-6 Schematic of...respectively (from left to right): I and II for the subcritical wave field and I and II for the supercritical wave field. Cross-sections I and II are

  8. Dark and Bright Ridges on Europa (United States)


    This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark 2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL galileo.

  9. Oak Ridge Reservation environmental report for 1989

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, V.A.; Wilson, A.R. (eds.)


    This two-volume report, the Oak Ridge Reservation Environmental Report for 1989, is the nineteenth in an annual series that began in 1971. It reports the results of a comprehensive, year-round program to monitor the impact of operations at the three major US Department of Energy (DOE) production and research installations in Oak Ridge on the immediate areas' and surrounding region's groundwater and surface waters, soil, air quality, vegetation and wildlife, and through these multiple and varied pathways, the resident human population. Information is presented for the environmental monitoring Quality Assurance (QA) Program, audits and reviews, waste management activities, land special environmental studies. Data are included for the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory (ORNL), and Oak Ridge Gaseous Diffusion Plant (ORGDP). Volume 1 presents narratives, summaries, and conclusions based on environmental monitoring at the three DOE installations and in the surrounding environs during calendar year (CY) 1989. Volume 1 is intended to be a stand-alone'' report about the Oak Ridge Reservation (ORR) for the reader who does not want an in-depth review of 1989 data. Volume 2 presents the detailed data from which these conclusions have been drawn and should be used in conjunction with Volume 1.

  10. Assessing the clarity of friction ridge impressions. (United States)

    Hicklin, R Austin; Buscaglia, JoAnn; Roberts, Maria Antonia


    The ability of friction ridge examiners to correctly discern and make use of the ridges and associated features in finger or palm impressions is limited by clarity. The clarity of an impression relates to the examiner's confidence that the presence, absence, and attributes of features can be correctly discerned. Despite the importance of clarity in the examination process, there have not previously been standard methods for assessing clarity in friction ridge impressions. We introduce a process for annotation, analysis, and interchange of friction ridge clarity information that can be applied to latent or exemplar impressions. This paper: (1) describes a method for evaluating the clarity of friction ridge impressions by using color-coded annotations that can be used by examiners or automated systems; (2) discusses algorithms for overall clarity metrics based on manual or automated clarity annotation; and (3) defines a method of quantifying the correspondence of clarity when comparing a pair of friction ridge images, based on clarity annotation and resulting metrics. Different uses of this approach include examiner interchange of data, quality assurance, metrics, and as an aid in automated fingerprint matching. Published by Elsevier Ireland Ltd.

  11. Photocatalysis Using Semiconductor Nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Thurston, T.R.; Wilcoxon,J.P.


    We report on experiments using nanosize MoS{sub 2} to photo-oxidize organic pollutants in water using visible light as the energy source. We have demonstrated that we can vary the redox potentials and absorbance characteristics of these small semiconductors by adjusting their size, and our studies of the photooxidation of organic molecules have revealed that the rate of oxidation increases with increasing bandgap (i.e. more positive valence band and more negative conduction band potentials). Because these photocatalysis reactions can be performed with the nanoclusters fully dispersed and stable in solution, liquid chromatography can be used to determine both the intermediate reaction products and the state of the nanoclusters during the reaction. We have demonstrated that the MoS{sub 2} nanoclusters remain unchanged during the photooxidation process by this technique. We also report on studies of MoS{sub 2} nanoclusters deposited on TiO{sub 2} powder.

  12. Semiconductor radiation detector (United States)

    Bell, Zane W.; Burger, Arnold


    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  13. Semiconductor optoelectronic infrared spectroscopy

    CERN Document Server

    Hollingworth, A R


    level separation. This showed for the first time evidence of the phonon bottleneck in a working laser device. A new technique called time resolved optically detected cyclotron resonance, was used as a precursor to finding the carrier dynamics within a spatially confined quantum dot. By moving to the case of a spatial QD using an optically detected intraband resonance it was possible to measure the energy separation interband levels and conduction and valence sublevels within the dot simultaneously. Furthermore this technique has been shown that the inhomogeneous broadening of the photoluminescence spectrum is not purely affected by just size and composition. We suggest that other processes such as state occupancy, In roughing, and exciton binding energies may account for the extra energy. We use spectroscopy to study infrared optoelectronic inter and intraband semiconductor carrier dynamics. The overall aim of this thesis was to study both III-V and Pb chalcogenide material systems in order to show their futu...

  14. Semiconductor adiabatic qubits

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Malcolm S.; Witzel, Wayne; Jacobson, Noah Tobias; Ganti, Anand; Landahl, Andrew J.; Lilly, Michael; Nguyen, Khoi Thi; Bishop, Nathaniel; Carr, Stephen M.; Bussmann, Ezra; Nielsen, Erik; Levy, James Ewers; Blume-Kohout, Robin J.; Rahman, Rajib


    A quantum computing device that includes a plurality of semiconductor adiabatic qubits is described herein. The qubits are programmed with local biases and coupling terms between qubits that represent a problem of interest. The qubits are initialized by way of a tuneable parameter, a local tunnel coupling within each qubit, such that the qubits remain in a ground energy state, and that initial state is represented by the qubits being in a superposition of |0> and |1> states. The parameter is altered over time adiabatically or such that relaxation mechanisms maintain a large fraction of ground state occupation through decreasing the tunnel coupling barrier within each qubit with the appropriate schedule. The final state when tunnel coupling is effectively zero represents the solution state to the problem represented in the |0> and |1> basis, which can be accurately read at each qubit location.

  15. Nano porous silicon microcavity sensor for determination organic solvents and pesticide in water (United States)

    Pham, Van Hoi; Van Nguyen, Thuy; Nguyen, The Anh; Pham, Van Dai; Bui, Huy


    In this paper we present a sensing method using nano-porous silicon microcavity sensor, which was developed in order to obtain simultaneous determination of two volatile substances with different solvent concentrations as well as very low pesticide concentration in water. The temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for different solvent solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations. On the other hand, this method is able to detect the presence of atrazine pesticide by the shift of the resonant wavelength, with good sensitivity (0.3 nm pg-1 ml) and limit of detection (LOD) (0.8-1.4 pg ml-1), that we tested for concentrations in the range from 2.15 to 21.5 pg ml-1, which is the range useful for monitoring acceptable water for human consumption.

  16. Simulations of emission from microcavity tandem organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Rana; Xu, Chun; Zhao, Weijun; Liu, Rui; Shinar, Ruth; Shinar, Joseph


    Microcavity tandem organic light-emitting diodes (OLEDs) are simulated and compared to experimental results. The simulations are based on two complementary techniques: rigorous finite element solutions of Maxwell's equations and Fourier space scattering matrix solutions. A narrowing and blue shift of the emission spectrum relative to the noncavity single unit OLED is obtained both theoretically and experimentally. In the simulations, a distribution of emitting sources is placed near the interface of the electron transport layer tris(8-hydroxyquinoline) Al (Alq{sub 3}) and the hole transport layer (N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine) ({alpha}-NPB). Far-field electric field intensities are simulated. The simulated widths of the emission peaks also agree with the experimental results. The simulations of the 2-unit tandem OLEDs shifted the emission to shorter wavelength, in agreement with experimental measurements. The emission spectra's dependence on individual layer thicknesses also agreed well with measurements. Approaches to simulate and improve the light emission intensity from these OLEDs, in particular for white OLEDs, are discussed.

  17. Temperature tunability of quantum emitter - cavity coupling in a photonic wire microcavity with shielded sidewall loss

    CERN Document Server

    Bernard, M


    Recent technological advancements have allowed to implement in solid-state cavity-based devices phenomena of quantum nature such as vacuum Rabi splitting, controllable single photon emission and quantum entanglement. For a sufficiently strong coupling between a quantum emitter and a cavity, large quality factors ($Q$) along with small modal volume ($V_{eff}$) are essential. Here we show that by applying a 5nm Al coating to the sidewalls of a submicrometer-sized Fabry-P\\'{e}rot microcavity, the cavity $Q$ can be temperature-tuned from few hundreds at room temperatures to 2$\\times$10$^5$ below 30~K. This is achieved by, first, a complete shielding of the sidewall loss with ideally reflecting lateral metallic mirrors and, secondly, a dramatic decrease of the cavity's axial loss for small-sized devices due to the largely off-axis wavevector within the multilayered structure. Our findings offer a novel temperature-tunable platform to study quantum electrodynamical phenomena of emitter-cavity coupling. We demonstra...

  18. Versatile tissue lasers based on high-Q Fabry-Pérot microcavities. (United States)

    Chen, Yu-Cheng; Chen, Qiushu; Zhang, Tingting; Wang, Wenjie; Fan, Xudong


    Biolasers are an emerging technology for next generation biochemical detection and clinical applications. Progress has recently been made to achieve lasing from biomolecules and single living cells. Tissues, which consist of cells embedded in an extracellular matrix, mimic more closely the actual complex biological environment in a living body and therefore are of more practical significance. Here, we developed a highly versatile tissue laser platform, in which tissues stained with fluorophores are sandwiched in a high-Q Fabry-Pérot microcavity. Distinct lasing emissions from muscle and adipose tissues stained respectively with fluorescein isothiocyanate (FITC) and boron-dipyrromethene (BODIPY), and hybrid muscle/adipose tissue with dual staining were achieved with a threshold of only ∼10 μJ mm-2. Additionally, we investigated how the tissue structure/geometry, tissue thickness, and staining dye concentration affect the tissue laser. Lasing emission from FITC conjugates (FITC-phalloidin) that specifically target F-actin in muscle tissues was also realized. It is further found that, despite the large fluorescence spectral overlap between FITC and BODIPY in tissues, their lasing emissions could be clearly distinguished and controlled due to their narrow lasing bands and different lasing thresholds, thus enabling highly multiplexed detection. Our tissue laser platform can be broadly applicable to various types of tissues/diseases. It provides a new tool for a wide range of biological and biomedical applications, such as diagnostics/screening of tissues and identification/monitoring of biological transformations in tissue engineering.

  19. Bragg polaritons in a ZnSe-based unfolded microcavity at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sebald, K.; Rahman, SK. S.; Cornelius, M.; Kaya, T.; Gutowski, J. [Semiconductor Optics, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klein, T.; Gust, A.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klembt, S. [Institut Néel, Université Grenoble Alpes and CNRS, B.P. 166, 38042 Grenoble (France)


    In this contribution, we present strong coupling of ZnSe quantum well excitons to Bragg modes resulting in the formation of Bragg polariton eigenstates, characterized by a small effective mass in comparison to a conventional microcavity. We observe an anticrossing of the excitonic and the photonic component in our sample being a clear signature for the strong-coupling regime. The anticrossing is investigated by changing the detuning between the excitonic components and the Bragg mode. We find anticrossings between the first Bragg mode and the heavy- as well as light-hole exciton, respectively, resulting in three polariton branches. The observed Bragg-polariton branches are in good agreement with theoretical calculations. The strong indication for the existence of strong coupling is traceable up to a temperature of 200 K, with a Rabi-splitting energy of 24 meV and 13 meV for the Bragg mode with the heavy- and light-hole exciton, respectively. These findings demonstrate the advantages of this sample configuration for ZnSe-based devices for the strong coupling regime.

  20. Tailoring the optical properties of wide-bandgap based microcavities via metal films

    Energy Technology Data Exchange (ETDEWEB)

    Sebald, K., E-mail:; Rahman, SK. S.; Cornelius, M.; Gutowski, J. [Semiconductor Optics, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klein, T.; Klembt, S.; Kruse, C.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany)


    We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

  1. Electrical pumping and tuning of exciton-polaritons in carbon nanotube microcavities (United States)

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


    Exciton-polaritons are hybrid light-matter particles that form upon strong coupling of an excitonic transition to a cavity mode. As bosons, polaritons can form condensates with coherent laser-like emission. For organic materials, optically pumped condensation was achieved at room temperature but electrically pumped condensation remains elusive due to insufficient polariton densities. Here we combine the outstanding optical and electronic properties of purified, solution-processed semiconducting (6,5) single-walled carbon nanotubes (SWCNTs) in a microcavity-integrated light-emitting field-effect transistor to realize efficient electrical pumping of exciton-polaritons at room temperature with high current densities (>10 kA cm-2) and tunability in the near-infrared (1,060 nm to 1,530 nm). We demonstrate thermalization of SWCNT polaritons, exciton-polariton pumping rates ~104 times higher than in current organic polariton devices, direct control over the coupling strength (Rabi splitting) via the applied gate voltage, and a tenfold enhancement of polaritonic over excitonic emission. This powerful material-device combination paves the way to carbon-based polariton emitters and possibly lasers.

  2. Detection of MMP-8 via porous silicon microcavity devices functionalized with human antibodies (United States)

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


    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).

  3. Monolithic integration of III-V nanowire with photonic crystal microcavity for vertical light emission. (United States)

    Larrue, Alexandre; Wilhelm, Christophe; Vest, Gwenaelle; Combrié, Sylvain; de Rossi, Alfredo; Soci, Cesare


    A novel photonic structure formed by the monolithic integration of a vertical III-V nanowire on top of a L3 two-dimensional photonic crystal microcavity is proposed to enhance light emission from the nanowire. The impact on the nanowire spontaneous emission rate is evaluated by calculating the spontaneous emission factor β, and the material gain at threshold is used as a figure of merit of this vertical emitting nanolaser. An optimal design is identified for a GaAs nanowire geometry with r = 155 nm and L~1.1 μm, where minimum gain at threshold (gth~13×10³ cm⁻¹) and large spontaneous emission factor (β~0.3) are simultaneously achieved. Modification of the directivity of the L3 photonic crystal cavity via the band-folding principle is employed to further optimize the far-field radiation pattern and to increase the directivity of the device. These results lay the foundation for a new approach toward large-scale integration of vertical emitting nanolasers and may enable applications such as intra-chip optical interconnects.

  4. Optical microcavities enhance the exciton coherence length and eliminate vibronic coupling in J-aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Spano, F. C. [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)


    The properties of polaritons in J-aggregate microcavities are explored using a Hamiltonian which treats exciton-vibrational coupling and exciton-photon coupling on equal footing. When the cavity mode is resonant with the lowest-energy (0-0) transition in the J-aggregate, two polaritons are formed, the lowest-energy polariton (LP) and its higher-energy partner (P{sub 1}), separated by the Rabi splitting. Strong coupling between the material and cavity modes leads to a decoupling of the exciton and vibrational degrees of freedom and an overall reduction of disorder within the LP. Such effects lead to an expanded material coherence length in the LP which leads to enhanced radiative decay rates. Additional spectral signatures include an amplification of the 0-0 peak coincident with a reduction in the 0-1 peak in the photoluminescence spectrum. It is also shown that the same cavity photon responsible for the LP/P{sub 1} splitting causes comparable splittings in the higher vibronic bands due to additional resonances between vibrationally excited states in the electronic ground state manifold and higher energy vibronic excitons.

  5. Microcavity Silicon Photodetectors at 1.55 μm

    Directory of Open Access Journals (Sweden)

    M. Casalino


    Full Text Available The design, the realization, and the characterization of silicon resonant cavity enhanced (RCE photodetectors, working at 1.55 μm, are reported. The photodetectors are constituted by a Fabry-Perot microcavity incorporating a Schottky diode. The working principle is based on the internal photoemission effect. We investigated two types of structures: top and back-illuminated. Concerning the top-illuminated photodetectors, a theoretical and numerical analysis has been provided and the device quantum efficiency has been calculated. Moreover, a comparison among three different photodetectors, having as Schottky metal: gold, silver, or copper, was proposed. Concerning the back-illuminated devices, two kinds of Cu/p-Si RCE photodetectors, having various bottom-mirror reflectivities, were realized and characterized. Device performances in terms of responsivity, free spectral range, and finesse were theoretically and experimentally calculated in order to prove an enhancement in efficiency due to the cavity effect. The back-illuminated device fabrication process is completely compatible with the standard silicon technology.

  6. Electrically Pumped III-N Microcavity Light Emitters Incorporating an Oxide Confinement Aperture (United States)

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


    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.

  7. Semiconductor-superconductor optoelectronic devices (United States)

    Bouscher, Shlomi; Panna, Dmitry; Hayat, Alex


    Devices combining superconductors with semiconductors offer a wide range of applications, particularly in the growing field of quantum information processing. This is due to their ability to take advantage of both the extensive knowledge gathered in the field of semiconductors and the unique quantum properties of superconductors. This results in novel device concepts, such as structures generating and detecting entangled photon pairs as well as novel optical gain and laser realizations. In this review, we discuss the fundamental concepts and the underlying physical phenomena of superconductor-semiconductor optoelectronics as well as practical device implementations.

  8. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul


    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  9. Numerical investigation of high-contrast ultrafast all-optical switching in low-refractive-index polymeric photonic crystal nanobeam microcavities (United States)

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


    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.

  10. Sea Ice Ridge Detection from ICESAR 2007 (United States)

    Zhu, Tingting; Spreen, Gunnar; Dierking, Wolfgang; Heygster, Georg; Li, Fei; Zhang, Yu; Zhang, Shengkai; Hao, Weifeng; Yuan, Lexian; Xiao, Feng


    Synthetic aperture radar (SAR) imagery can be used to capture sea ice surface deformation features including rafted ice, shear zones, pressure ridges and rubble ice caused by the divergence, convergence and shear of sea ice. It has been shown that pressure ridges can be observed as bright, curvilinear features in C-band and L-band SAR satellite images. A comparison of airborne L-band and C-band SAR data to identify deformation features (ridge) has concluded that L-band is preferable in most cases. To investigate in more detail how sea ice can be observed by SAR, the airborne measurement campaign ICESAR 2007 has been conducted. In this study, we use L-band and C-band airborne SAR data sets to detect ridges from the ICESAR 2007 campaign. Our region of interest (ROI) is the Fram Strait. One goal of this study is to identify possibilities if deformed ice areas can also be detected with the lower resolution (40 m) SAR of the Sentinel-1 satellite mission. We therefore consider the parameter configurations of the Sentinel-1 mission as a baseline in our study. Traditional techniques for ridge detection include line detection, edge detection, and direct threshold method. These methods are insufficient without considering the intensive speckle noise and contextual information in such high spatial resolution SAR imagery like we use here from ICESAR 2007. Another obstacle is to separate ridges from other deformed features in the SAR imagery. For tackling these issues, we propose using a structure tensor algorithm for ridge detection in the ICESAR 2007 data sets. For the tensor structure algorithm, sea ice ridges are described as the target enhanced by the tensor matrix and surrounding pixels are suppressed as the background using the weighted gradient distance. The length to width ratio is used to preserve ridge shaped features and avoids that they are being filtered out as noise. The structure tensor algorithm is validated for the ICESAR L-band HH and HV SAR imagery with a

  11. Sea ice ridging in the eastern Weddell Sea (United States)

    Lytle, V. I.; Ackley, S. F.


    In August 1986, sea ice ridge heights and spatial frequency in the eastern Weddell Sea were measured using a ship-based acoustical sounder. Using a minimum ridge sail height of 0.75 m, a total of 933 ridges were measured along a track length of 415 km. The ridge frequency varied from 0.4 to 10.5 ridges km-1. The mean height of the ridges was found to be about 1.1 m regardless of the ridge frequency. These results are compared to other ridging statistics from the Ross Sea and found to be similar. Comparison with Arctic data, however, indicates that the height and frequency of the ridges are considerably less in the Weddell Sea than in the Arctic. Whereas in the Arctic the mean ridge height tends to increase with the ridge frequency, we found that this was not the case in the Weddell Sea, where the mean ridge height remained constant irrespective of the ridge frequency. Estimates of the contribution of deformed ice to the total ice thickness are generally low except for a single 53-km section where the ridge frequency increased by an order of magnitude. This resulted in an increase in the equivalent mean ice thickness due to ridging from 0.04 m in the less deformed areas to 0.45 m in the highly deformed section. These values were found to be consistent with values obtained from drilled profile lines during the same cruise.

  12. Toward designing semiconductor-semiconductor heterojunctions for photocatalytic applications (United States)

    Zhang, Liping; Jaroniec, Mietek


    Semiconductor photocatalysts show a great potential for environmental and energy-related applications, however one of the major disadvantages is their relatively low photocatalytic performance due to the recombination of electron-hole pairs. Therefore, intensive research is being conducted toward design of heterojunctions, which have been shown to be effective for improving the charge-transfer properties and efficiency of photocatalysts. According to the type of band alignment and direction of internal electric field, heterojunctions are categorized into five different types, each of which is associated with its own charge transfer characteristics. Since the design of heterojunctions requires the knowledge of band edge positions of component semiconductors, the commonly used techniques for the assessment of band edge positions are reviewed. Among them the electronegativity-based calculation method is applied for a large number of popular visible-light-active semiconductors, including some widely investigated bismuth-containing semiconductors. On basis of the calculated band edge positions and the type of component semiconductors reported, heterojunctions composed of the selected bismuth-containing semiconductors are proposed. Finally, the most popular synthetic techniques for the fabrication of heterojunctions are briefly discussed.

  13. Preliminary results from the first InRidge cruise to the central Indian Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Murthy, K.S.R.; Iyer, S.D.; Rao, M.M.M.; Banerjee, R.; Subrahmanyam, A.S.; Shirodkar, P.V.; Ghose, I.; Ganesan, P.; Rao, A.K.; Suribabu, A.; Ganesh, C.; Naik, G.P.

    stream_size 1 stream_content_type text/plain stream_name Inter_Ridge_News_7_40.pdf.txt stream_source_info Inter_Ridge_News_7_40.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  14. The Northern Central Indian Ridge: Geology and tectonics of fracture zones-dominated spreading ridge segments

    Digital Repository Service at National Institute of Oceanography (India)

    Drolia, R.K.; Iyer, S.D.; Chakraborty, B; Kodagali, V.N.; Ray, Dwijesh; Misra, S.; Andrade, R.; Sarma, K.V.L.N.S.; Rajasekhar, R.P.; Mukhopadhyay, R.

    . The ridge segments are characterized by along-axis depth variation: deepening at segment ends and shallowing at the centre. Both the ridge axis and TF areas are complex with intra- and inter-segmental morphotectonic and magnetic variations. Basalts collected...

  15. Ridge trace as a boost to ridge regression estimate in the presence ...

    African Journals Online (AJOL)

    Multicollinearity often causes a huge interpretative problem in linear regression analysis. The ridge estimator is not generally accepted as a vital alternative to the ordinary least squares (OLS) estimator because it depends on unknown parameters. In any specific application of ridges regression, there is no guarantee that ...

  16. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong


    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  17. Semiconductor radiation detectors. Device physics

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [Max-Planck-Institutes for Physics and Extraterrestrial Physics, Muenchen (Germany). Semiconductor Lab.


    Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)

  18. Physics of semiconductor laser devices

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, G.H.B.


    Aspects of laser design and development are considered along with semiconductor materials for lasers, problems of device fabrication, crystal growth, the degradation of lasers, and the integration of semiconductor lasers with other optical components. A description is presented of light emission processes and laser action in semiconductors, taking into account electronic radiative transitions, the relation between emission and absorption processes, transition probabilities, the density of electron states in the highly doped semiconductor, carrier recombination and spontaneous emission, the gain/current relation, light-current characteristics, optical modes, and the evolution of mode spectrum and intensity with current. Attention is given to laser heterostructures and the properties of heterojunctions, optical waveguides, the performance of heterostructure lasers, stripe geometry lasers, and the dynamic response of lasers. Lasers with distributed feedback and Bragg reflectors are also discussed.

  19. Energy transfer with semiconductor nanocrystals

    NARCIS (Netherlands)

    Rogach, A.L.; Klar, T.A.; Lupton, J.M.; Meijerink, A.; Feldmann, J.


    Fo¨ rster (or fluorescence) resonant energy transfer (FRET) is a powerful spectroscopic technique to study interactions, conformational and distance changes, in hybrid nanosystems. Semiconductor nanocrystals, also known as colloidal quantum dots, are highly efficient fluorophores with a strong

  20. Ballistic superconductivity in semiconductor nanowires

    NARCIS (Netherlands)

    Zhang, H.; Gül, Ö.; Conesa-Boj, S.; Nowak, M.P.; Wimmer, M.; Zuo, K.; Mourik, V.; Vries, F.K. de; Veen, J. van; Moor, M.W.A. de; Bommer, J.D.S.; Woerkom, D.J. van; Car, D.; Plissard, S.R.; Bakkers, E.P.A.M.; Quintero Pérez, M.; Cassidy, M.C.; Koelling, S.; Goswami, S.; Watanabe, K.; Taniguchi, T.; Kouwenhoven, L.P.


    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of

  1. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank


    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  2. Semiconductor nanocrystals or quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 8. Various Quantum Mechanical Concepts for Confinements in Semiconductor Nanocrystals. Jayakrishna Khatei Karuna Kar Nanda. Classroom Volume 18 Issue 8 August 2013 pp 771-776 ...

  3. Energy-selective optical excitation and detection in InAs/InP quantum dot ensembles using a one-dimensional optical microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Gamouras, A.; Britton, M.; Khairy, M. M.; Mathew, R.; Hall, K. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H4R2 (Canada); Dalacu, D.; Poole, P.; Poitras, D.; Williams, R. L. [Institute for Microstructural Sciences, National Research Council of Canada, Ottawa K1A 0R6 (Canada)


    We demonstrate the selective optical excitation and detection of subsets of quantum dots (QDs) within an InAs/InP ensemble using a SiO{sub 2}/Ta{sub 2}O{sub 5}-based optical microcavity. The low variance of the exciton transition energy and dipole moment tied to the narrow linewidth of the microcavity mode is expected to facilitate effective qubit encoding and manipulation in a quantum dot ensemble with ease of quantum state readout relative to qubits encoded in single quantum dots.

  4. Semiconductor packaging materials interaction and reliability

    CERN Document Server

    Chen, Andrea


    In semiconductor manufacturing, understanding how various materials behave and interact is critical to making a reliable and robust semiconductor package. Semiconductor Packaging: Materials Interaction and Reliability provides a fundamental understanding of the underlying physical properties of the materials used in a semiconductor package. The book focuses on an important step in semiconductor manufacturing--package assembly and testing. It covers the basics of material properties and explains how to determine which behaviors are important to package performance. The authors also discuss how

  5. Fractal properties of nanostructured semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhanabaev, Z.Zh. [Al-Farabi Khazakh National University, Tole bi Street, 96, Almaty 050012 (Kazakhstan); Grevtseva, T.Yu. [Al-Farabi Khazakh National University, Tole bi Street, 96, Almaty 050012 (Kazakhstan)]. E-mail:


    A theory for the temperature and time dependence of current carrier concentration in semiconductors with different non-equilibrium nanocluster structure has been developed. It was shown that the scale-invariant fractal self-similar and self-affine laws can exist near by the transition point to the equilibrium state. Results of the theory have been compared to the experimental data from electrical properties of semiconductor films with nanoclusters.

  6. Dissipative chaos in semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    F. Moghadam


    Full Text Available In this paper the motion of electron in a miniband of a semiconductor superlattice (SSL under the influence of external electric and magnetic fields is investigated. The electric field is applied in a direction perpendicular to the layers of the semiconductor superlattice, and the magnetic field is applied in different direction Numerical calculations show conditions led to the possibility of chaotic behaviors.

  7. Nonlinear Optical Interactions in Semiconductors. (United States)


    Physique du Solide et Energie Solaire We had on-going interaction with Dr. Christian Verie on the growth of high quality narrow-gap semiconductor crystals...The band gap energy of the semiconductor decreases with increasing temperature. Consequently, the absorption of light in the energy region of the...gas and, more importantly, will modulate the electron energy at the difference frequency, wI - 02" Under ordinary circumstances such an energy (or

  8. Lithospheric Flexural Modeling of Iapetus' Equatorial Ridge (United States)

    Zheng, W.; Ip, W.-H.; Teng, L. S.


    Iapetus, which is one of Saturn's ball-shaped satellites, has some unique features in the Solar System. This satellite has a mean radius of 735 km, and there is an approximately 20-kilometer-high mountain lying precisely on its equator. The mountain is known as an "equatorial ridge" since it makes Iapetus appear walnut shaped. The origin of the equatorial ridge is attributed to several hypotheses, including different endogenesis and exogenesis processes. In this work, we attempted to construct a flexural model of the equatorial ridge using elastic lithosphere theory. The equatorial ridge is treated as a linear load which exerts uniform force on Iapetus' hard shell (i.e. elastic lithosphere of Iapetus). To calculate the deflection of surface, we use the Digital Terrain Model (DTM) data of Iapetus' leading side published by Giese et al. (2008). Giese et al. also pointed out that the elastic lithospheric thickness of Iapetus must exceed 100 km to support the ridge without deflecting. However, we found possible evidence in the DTM data that implied deflection. There are two sites of surface depression on the northern side of the equatorial ridge. The few-kilometer deflection implies a thinner lithosphere than previous suggested. Assume that the thickness of elastic lithosphere is only 5% below of the radius of Iapetus, so the flat-Earth and one-plate condition could adapt to the flexure model of Iapetus. Based on analysis of the distance between a bulge and the ridge, the calculated lithospheric thickness is 6-10 km. The new result seems controversial, but the modeled surface profile is highly consistent with numerical ridge DTM profile extracted from Giese et al. (2008). Thinner lithosphere also supports the contraction model proposed by Sandwell and Schubert (2010) since the bucking harmonic degree increases. In the other hand, the transformation layer between hard shell and plastic inner core may need constraint on thermal history or crystal form of ice. In

  9. Biomechanical comparison of a novel engine-driven ridge spreader and conventional ridge splitting techniques. (United States)

    Jung, Gyu-Un; Kim, Jun Hwan; Lim, Nam Hun; Yoon, Gil Ho; Han, Ji-Young


    Ridge splitting techniques are used for horizontal ridge augmentation in implant dentistry. Recently, a novel engine-driven ridge splitting technique was introduced. This study compared the mechanical forces produced by conventional and engine-driven ridge splitting techniques in porcine mandibles. In 33 pigs, mandibular premolar areas were selected for the ridge splitting procedures, designed as a randomized split-mouth study. The conventional group underwent a chisel-and-mallet procedure (control group, n = 20), and percussive impulse (Newton second, Ns) was measured using a sensor attached to the mallet. In the engine-driven ridge spreader group (test group, n = 23), a load cell was used to measure torque values (Newton centimeter, Ncm). Horizontal acceleration generated during procedures (control group, n = 10 and test group, n = 10) was compared between the groups. After ridge splitting, the alveolar crest width was significantly increased both in the control (1.23 ± 0.45 mm) and test (0.98 ± 0.41 mm) groups with no significant differences between the groups. The average impulse of the control group was 4.74 ± 1.05 Ns. Torque generated by rotation in the test group was 9.07 ± 2.15 Ncm. Horizontal acceleration was significantly less in the test group (0.82 ± 1.05 g) than the control group (64.07 ± 42.62 g) (P engine-driven ridge spreaders. Within the limits of this study, the results suggested that an engine-driven ridge splitting technique may be less traumatic and less invasive than a conventional ridge splitting technique. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)


    This document outlines the activities necessary to conduct a Remedial Investigation (RI) of the Chestnut Ridge Security Pits (CRSP) at the Oak Ridge Y-12 Plant. The CRSP, also designated Chestnut Ridge Operable Unit (OU) 1, is one of four OUs along Chestnut Ridge on the Oak Ridge Reservation (ORR). The purpose of the RI is to collect data to (1) evaluate the nature and extent of known and suspected contaminants, (2) support an Ecological Risk Assessment (ERA) and a Human Health Risk Assessment (HHRA), (3) support the feasibility study in the development and analysis of remedial alternatives, and (4) ultimately, develop a Record of Decision (ROD) for the site. This chapter summarizes the regulatory background of environmental investigation on the ORR and the approach currently being followed and provides an overview of the RI to be conducted at the CRSP. Subsequent chapters provide details on site history, sampling activities, procedures and methods, quality assurance (QA), health and safety, and waste management related to the RI.

  11. Survey of cryogenic semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Talarico, L.J.; McKeever, J.W.


    Improved reliability and electronic performance can be achieved in a system operated at cryogenic temperatures because of the reduction in mechanical insult and in disruptive effects of thermal energy on electronic devices. Continuing discoveries of new superconductors with ever increasing values of T{sub c} above that of liquid nitrogen temperature (LNT) have provided incentive for developing semiconductor electronic systems that may also operate in the superconductor`s liquid nitrogen bath. Because of the interest in high-temperature superconductor (HTS) devices, liquid nitrogen is the cryogen of choice and LNT is the temperature on which this review is focused. The purpose of this survey is to locate and assemble published information comparing the room temperature (298 K), performance of commercially available conventional and hybrid semiconductor device with their performance at LNT (77K), to help establish their candidacy as cryogenic electronic devices specifically for use at LNT. The approach to gathering information for this survey included the following activities. Periodicals and proceedings were searched for information on the behavior of semiconductor devices at LNT. Telephone calls were made to representatives of semiconductor industries, to semiconductor subcontractors, to university faculty members prominent for their research in the area of cryogenic semiconductors, and to representatives of the National Aeronautics and Space Administration (NASA) and NASA subcontractors. The sources and contacts are listed with their responses in the introduction, and a list of references appears at the end of the survey.

  12. The ATLAS semiconductor tracker

    CERN Document Server

    Mikuz, Marko


    The ATLAS Semiconductor Tracker (SCT) is presented. About 16000 silicon micro-strip sensors with a total active surface of over 60 m **2 and with 6.3 million read-out channels are built into 4088 modules arranged into four barrel layers and nine disks covering each of the forward regions up to an eta of 2.5. Challenges are imposed by the hostile radiation environment with particle fluences up to 2 multiplied by 10**1**4 cm**-**2 1 MeV neutron NIEL equivalent and 100 kGy TID, the 25 ns LHC bunch crossing time and the need for a hermetic, lightweight tracker. The solution adopted is carefully designed strip detectors operated at -7 degree C, biased up to 500 V and read out by binary radhard fast BiCMOS electronics. A zero-CTE carbon fibre structure provides mechanical support. 30 kW of power are supplied on aluminiutn/Kapton tapes and cooled by C//3F//8 evaporative cooling. Data and commands are transferred by optical links. Prototypes of detector modules have been built, irradiated to the maximum expected flue...

  13. Two-photon interference from a quantum dot-microcavity: Persistent pure-dephasing and suppression of time-jitter

    DEFF Research Database (Denmark)

    Unsleber, Sebastian; McCutcheon, Dara; Dambach, Michael


    We demonstrate the emission of highly indistinguishable photons from a quasi-resonantly pumped coupledquantum dot–microcavity system operating in the regime of cavity quantum electrodynamics. Changing thesample temperature allows us to vary the quantum dot–cavity detuning and, on spectral resonance......, we observea threefold improvement in the Hong-Ou-Mandel interference visibility, reaching values in excess of 80%. Ourmeasurements off-resonance allow us to investigate varying Purcell enhancements, and to probe the dephasingenvironment at different temperatures and energy scales. By comparison...

  14. Two-photon interference from a quantum dot-microcavity: Persistent pure-dephasing and suppression of time-jitter

    DEFF Research Database (Denmark)

    Unsleber, S.; McCutcheon, Dara; Dambach, M.

    We demonstrate the emission of highly indistinguishable photons from a quasiresonantly pumped coupled quantum dot–microcavity system operating in the regime of cavity quantum electrodynamics. Changing the sample temperature allows us to vary the quantum dot–cavity detuning, and on spectral...... resonance we observe a three-fold improvement in the Hong–Ou–Mandel interference visibility, reaching values in excess of 80%. By comparison with our microscopic model, we are able to identify pure-dephasing and not time-jitter as the dominating source of imperfections in our system....

  15. Suppression of spontaneous emission for two-dimensional GaAs photonic crystal microcavities

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Broeng, Jes; Bjarklev, Anders Overgaard


    Summary form only given. Spontaneous emission represents a loss mechanism that fundamentally limits the performance of semiconductor lasers. The rate of spontaneous emission may, however, be controlled by a new class of periodic dielectric structures known as photonic crystals. Although a three...

  16. EDITORIAL: Oxide semiconductors (United States)

    Kawasaki, M.; Makino, T.


    Blue or ultraviolet semiconducting light-emitting diodes have the potential to revolutionize illumination systems in the near-future. Such industrial need has propelled the investigation of several wide-gap semiconducting materials in recent years. Commercial applications include blue lasers for DVD memory and laser printers, while military applications are also expected. Most of the material development has so far been focused on GaN (band gap 3.5 eV at 2 K), and ZnSe (2.9 eV) because these two representative direct transition semiconductors are known to be bright emitting sources. GaN and GaN-based alloys are emerging as the winners in this field because ZnSe is subject to defect formation under high current drive. On the other hand, another II-VI compound, ZnO, has also excited substantial interest in the optoelectronics-oriented research communities because it is the brightest emitter of all, owing to the fact that its excitons have a 60 meV binding energy. This is compared with 26 meV for GaN and 20 meV for ZnSe. The stable excitons could lead to laser action based on their recombination even at temperatures well above room temperature. ZnO has additional major properties that are more advantageous than other wide-gap materials: availability of large area substrates, higher energy radiation stability, environmentally-friendly ingredients, and amenability to wet chemical etching. However, ZnO is not new to the semiconductor field as exemplified by several studies made during the 1960s on structural, vibrational, optical and electrical properties (Mollwo E 1982 Landolt-Boernstein New Series vol 17 (Berlin: Springer) p 35). In terms of devices, the luminescence from light-emitting diode structures was demonstrated in which Cu2O was used as the p-type material (Drapak I T 1968 Semiconductors 2 624). The main obstacle to the development of ZnO has been the lack of reproducible p-type ZnO. The possibility of achieving epitaxial p-type layers with the aid of thermal

  17. Physiography of eastern Mendocino Ridge, NE Pacific (United States)

    Gardner, J. V.; Malik, M. A.; Verplank, N. S.


    The bathymetry of the eastern 850 km of Mendocino Ridge (MR) was mapped using NOAA Ship Okeanos Explorer’s Kongsberg EM302 multibeam as part of mapping trials to support the University of New Hampshire’s U.S. Law of the Sea mapping program. The ridge was mapped from the margin to ~500 km west of the intersection of the ridge with Gorda Ridge (GR) at a spatial resolution of 40 m/sounding. The mapped section can be subdivided into two morphologic styles. East of the GR intersection, along the transform fault, MR is a single 4-18 km wide ridge with summit depths of 1200 to 1700 m deep with slopes of 10-40°. West of the intersection, along the fracture zone, MR has summit depths of >2100 m deep. A series of drag folds formed by basement ridges west of GR and north of the fracture zone reflects the differential spreading rates of GR. The almost 90° bend in the drag folds is often accompanied by large volcanic fields with summit craters in many volcanoes in water depths of 2 to 4 km. Beginning ~45 km west of GR intersection, MR evolves into a series of en echelon ridges striking 290°, some with slopes as steep as 55°. The change in morphology appears to be the effects of compression in the transform fault section between the Gorda Plate to the north and the Pacific Plate to the south, whereas extension is evident in the fracture zone section of the ridge. Mendocino Channel immediately to the north of the easternmost MR was mapped from the margin to ~105 km to the west before the channel relief was below the resolution of the multibeam system. The channel walls have as much as 50 m of relief with decreasing relief down channel. Mendocino Channel is bordered on the north by a large field of levees with bedforms and on the south by the 1200 m high wall of MR. Several large sediment failures have occurred in the levee field. The channel is straight for the first 40+ km with an average channel slope of 0.7° but suddenly begins to meander when the channel slope is

  18. Progress Toward Single-Photon-Level Nonlinear Optics in Crystalline Microcavities (United States)

    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

  19. Ridge Splitting Technique for Horizontal Augmentation and Immediate Implant Placement

    Directory of Open Access Journals (Sweden)

    Papathanasiou Ioannis


    Full Text Available Insufficient width of the alveolar ridge often prevents ideal implant placement. Guided bone regeneration, bone grafting, alveolar ridge splitting and combinations of these techniques are used for the lateral augmentation of the alveolar ridge. Ridge splitting is a minimally invasive technique indicated for alveolar ridges with adequate height, which enables immediate implant placement and eliminates morbidity and overall treatment time. The classical approach of the technique involves splitting the alveolar ridge into 2 parts with use of ostetomes and chisels. Modifications of this technique include the use of rotating instrument, screw spreaders, horizontal spreaders and ultrasonic device.

  20. Fabrication and investigation of photonic crystal microcavities for solid state quantum optics (United States)

    Kress, Andreas; Hofbauer, Felix; Reinelt, Norbert; Kaniber, M.; Bichler, Max; Schuh, Dieter; Boehm, Gerhard; Finley, Jonathan J.


    We review our recent progress in the fabrication and understanding of ultra-low mode volume, high Q-factor microcavities for quantum dot based cavity QED experiments. The cavities are realized by the controlled incorporation of defects into 2D photonic crystals that consist of a triangular lattice of air holes within an active Air-GaAs-Air slab waveguide containing InGaAs self-assembled quantum dots. Two specific cavity designs are studied: the L3-cavity consisting of three missing holes along a line and the Y1-cavity consisting of a single missing hole with strongly reduced symmetry. Very good quantitative agreement is obtained between the results of spatially resolved optical spectroscopy and 3D calculations of the photonic bandstructure and cavity mode structure. For both cavity designs, cavity Q-factors up to ~8000 are measured for specific designs with ultra-low mode volumes Vmode< (λ/n)3. The relative contribution of cavity losses due to out of plane coupling to the free space continuum, in-plane losses through the photonic crystal and via scattering due to disorder and fabrication imperfections are probed for both cavity designs. We demonstrate that in-plane loss can be almost completely inhibited by tuning the localized cavity modes deeper into the photonic bandgap and the potential to fine tune the out-of plane losses via subtle modifications of the cavity design parameters. This procedure is shown to result in up to ~3x improvements of the cavity Q-factor. The Y1-design is shown to be particularly suitable for QD based cavity QED experiments, due to its very low mode volume, high Q-factors achievable (~7000) and flexibility for enhancement through careful modification of the cavity design.

  1. Wide-Bandgap Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, M.S.


    With the increase in demand for more efficient, higher-power, and higher-temperature operation of power converters, design engineers face the challenge of increasing the efficiency and power density of converters [1, 2]. Development in power semiconductors is vital for achieving the design goals set by the industry. Silicon (Si) power devices have reached their theoretical limits in terms of higher-temperature and higher-power operation by virtue of the physical properties of the material. To overcome these limitations, research has focused on wide-bandgap materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond because of their superior material advantages such as large bandgap, high thermal conductivity, and high critical breakdown field strength. Diamond is the ultimate material for power devices because of its greater than tenfold improvement in electrical properties compared with silicon; however, it is more suited for higher-voltage (grid level) higher-power applications based on the intrinsic properties of the material [3]. GaN and SiC power devices have similar performance improvements over Si power devices. GaN performs only slightly better than SiC. Both SiC and GaN have processing issues that need to be resolved before they can seriously challenge Si power devices; however, SiC is at a more technically advanced stage than GaN. SiC is considered to be the best transition material for future power devices before high-power diamond device technology matures. Since SiC power devices have lower losses than Si devices, SiC-based power converters are more efficient. With the high-temperature operation capability of SiC, thermal management requirements are reduced; therefore, a smaller heat sink would be sufficient. In addition, since SiC power devices can be switched at higher frequencies, smaller passive components are required in power converters. Smaller heat sinks and passive components result in higher-power-density power converters

  2. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji


    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  3. Normalization Ridge Regression in Practice I: Comparisons Between Ordinary Least Squares, Ridge Regression and Normalization Ridge Regression. (United States)

    Bulcock, J. W.

    The problem of model estimation when the data are collinear was examined. Though the ridge regression (RR) outperforms ordinary least squares (OLS) regression in the presence of acute multicollinearity, it is not a problem free technique for reducing the variance of the estimates. It is a stochastic procedure when it should be nonstochastic and it…

  4. Spatial inhomogeneous barrier heights at graphene/semiconductor Schottky junctions (United States)

    Tomer, Dushyant

    Graphene, a semimetal with linear energy dispersion, forms Schottky junction when interfaced with a semiconductor. This dissertation presents temperature dependent current-voltage and scanning tunneling microscopy/spectroscopy (STM/S) measurements performed on graphene Schottky junctions formed with both three and two dimensional semiconductors. To fabricate Schottky junctions, we transfer chemical vapor deposited monolayer graphene onto Si- and C-face SiC, Si, GaAs and MoS2 semiconducting substrates using polymer assisted chemical method. We observe three main type of intrinsic spatial inhomogeneities, graphene ripples, ridges and semiconductor steps in STM imaging that can exist at graphene/semiconductor junctions. Tunneling spectroscopy measurements reveal fluctuations in graphene Dirac point position, which is directly related to the Schottky barrier height. We find a direct correlation of Dirac point variation with the topographic undulations of graphene ripples at the graphene/SiC junction. However, no such correlation is established at graphene/Si and Graphene/GaAs junctions and Dirac point variations are attributed to surface states and trapped charges at the interface. In addition to graphene ripples and ridges, we also observe atomic scale moire patterns at graphene/MoS2 junction due to van der Waals interaction at the interface. Periodic topographic modulations due to moire pattern do not lead to local variation in graphene Dirac point, indicating that moire pattern does not contribute to fluctuations in electronic properties of the heterojunction. We perform temperature dependent current-voltage measurements to investigate the impact of topographic inhomogeneities on electrical properties of the Schottky junctions. We observe temperature dependence in junction parameters, such as Schottky barrier height and ideality factor, for all types of Schottky junctions in forward bias measurements. Standard thermionic emission theory which assumes a perfect

  5. Ridge regression estimator: combining unbiased and ordinary ridge regression methods of estimation

    Directory of Open Access Journals (Sweden)

    Sharad Damodar Gore


    Full Text Available Statistical literature has several methods for coping with multicollinearity. This paper introduces a new shrinkage estimator, called modified unbiased ridge (MUR. This estimator is obtained from unbiased ridge regression (URR in the same way that ordinary ridge regression (ORR is obtained from ordinary least squares (OLS. Properties of MUR are derived. Results on its matrix mean squared error (MMSE are obtained. MUR is compared with ORR and URR in terms of MMSE. These results are illustrated with an example based on data generated by Hoerl and Kennard (1975.

  6. Cooling and Laser-Induced Fluorescence of Electronically-Excited He2 in a Supersonic Microcavity Plasma Jet (United States)

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


    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.

  7. Enhanced green fluorescent protein in optofluidic Fabry-Perot microcavity to detect laser induced temperature changes in a bacterial culture (United States)

    Lahoz, F.; Martín, I. R.; Walo, D.; Freire, R.; Gil-Rostra, J.; Yubero, F.; Gonzalez-Elipe, A. R.


    Thermal therapy using laser sources can be used in combination with other cancer therapies to eliminate tumors. However, high precision temperature control is required to avoid damage in healthy surrounding tissues. Therefore, in order to detect laser induced temperature changes, we have used the fluorescence signal of the enhanced Green Fluorescent Protein (eGFP) over-expressed in an E. coli bacterial culture. For that purpose, the bacteria expressing eGFP are injected in a Fabry-Perot (FP) optofluidic planar microcavity. In order to locally heat the bacterial culture, external infrared or ultraviolet lasers were used. Shifts in the wavelengths of the resonant FP modes are used to determine the temperature increase as a function of the heating laser pump power. Laser induced local temperature increments up to 6-7 °C were measured. These results show a relatively easy way to measure laser induced local temperature changes using a FP microcavity and using eGFP as a molecular probe instead of external nanoparticles, which could damage/alter the cell. Therefore, we believe that this approach can be of interest for the study of thermal effects in laser induced thermal therapies.

  8. Pump-Power-Driven Mode Switching in a Microcavity Device and Its Relation to Bose-Einstein Condensation

    Directory of Open Access Journals (Sweden)

    H. A. M. Leymann


    Full Text Available We investigate the switching of the coherent emission mode of a bimodal microcavity device, occurring when the pump power is varied. We compare experimental data to theoretical results and identify the underlying mechanism based on the competition between the effective gain, on the one hand, and the intermode kinetics, on the other. When the pumping is ramped up, above a threshold, the mode with the largest effective gain starts to emit coherent light, corresponding to lasing. In contrast, in the limit of strong pumping, it is the intermode kinetics that determines which mode acquires a large occupation and shows coherent emission. We point out that this latter mechanism is akin to the equilibrium Bose-Einstein condensation of massive bosons. Thus, the mode switching in our microcavity device can be viewed as a minimal instance of Bose-Einstein condensation of photons. Moreover, we show that the switching from one cavity mode to the other always occurs via an intermediate phase where both modes are emitting coherent light and that it is associated with both superthermal intensity fluctuations and strong anticorrelations between both modes.

  9. Multiplexed specific label-free detection of NCI-H358 lung cancer cell line lysates with silicon based photonic crystal microcavity biosensors. (United States)

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


    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Mid-oceanic ridges - Guest editorial

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Iyer, S.D.

    Ins titutes of Techno logy and national laboratories. A few Inter national re - searchers, notably from the USA, Portugal, France and J a pan too have shown interest in the I n Ridge and are keen to collaborate with India. It is foreseen that In...

  11. Oak Ridge reservation land-use plan

    Energy Technology Data Exchange (ETDEWEB)

    Bibb, W. R.; Hardin, T. H.; Hawkins, C. C.; Johnson, W. A.; Peitzsch, F. C.; Scott, T. H.; Theisen, M. R.; Tuck, S. C.


    This study establishes a basis for long-range land-use planning to accommodate both present and projected DOE program requirements in Oak Ridge. In addition to technological requirements, this land-use plan incorporates in-depth ecological concepts that recognize multiple uses of land as a viable option. Neither environmental research nor technological operations need to be mutually exclusive in all instances. Unique biological areas, as well as rare and endangered species, need to be protected, and human and environmental health and safety must be maintained. The plan is based on the concept that the primary use of DOE land resources must be to implement the overall DOE mission in Oak Ridge. This document, along with the base map and overlay maps, provides a reasonably detailed description of the DOE Oak Ridge land resources and of the current and potential uses of the land. A description of the land characteristics, including geomorphology, agricultural productivity and soils, water courses, vegetation, and terrestrial and aquatic animal habitats, is presented to serve as a resource document. Essentially all DOE land in the Oak Ridge area is being fully used for ongoing DOE programs or has been set aside as protected areas.

  12. Oak Ridge Reservation Waste Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Turner, J.W. [ed.


    This report presents the waste management plan for the Oak Ridge Reservation facilities. The primary purpose is to convey what facilities are being used to manage wastes, what forces are acting to change current waste management systems, and what plans are in store for the coming fiscal year.

  13. Anelastic Semigeostrophic Flow Over a Mountain Ridge

    National Research Council Canada - National Science Library

    Bannon, Peter R; Chu, Pe-Cheng


    ...) characterize the disturbance generated by the steady flow of a uniform wind (U0, V0) incident on a mountain ridge of width alpha in an isothermal, uniformly rotating, uniformly stratified, vertically semi-infinite atmosphere. Here mu = h(0)/H(R...

  14. tilled soil under different ridge width

    African Journals Online (AJOL)



    Sep 21, 2011 ... in different agricultural system with a wide variety of climate, crops and labour intensity. Several strategies have been investigated that ridges could affect soil temperature and water content, as well as soil water and solute movement compared with traditional flat farming. (Waddell and Weil, 2006). Willis et ...

  15. Seismic response of a Taiwanese ridge (United States)

    Rault, Claire; Meunier, Patrick; Burtin, Arnaud; Wein Hao, Vvn; Wu, Yih-Min; Marc, Odin; Lai, Tz-Shin; Lyon-Caen, Hélène; Hovius, Niels


    A line of 6 broadband seismometers have been deployed across a ridge in the Hualien County (Eastern Taiwan) in order to study the seismic response of the hill. From March 2015 to June 2016, the network has been continuously recording waves incoming from the Taiwanese regional seismicity. The hill is well approximated by a triangular topography of 3600m in length by 900m in height. We present the primarily analysis performed on 1272 earthquakes of of magnitude (Ml) greater than Ml=3 and less than 200km distant to the study site. We show that most of the uphill records exhibit a systematic amplification of seismic waves (peak to peak velocity) on the resonance frequency band of the ridge [0,5-3Hz] with respect to the referenced records at the base of the hill. Amplification on sharp frequency band also occurs in other sites, reflecting complex local site effects. We found that the average amplification at the top on the transverse component to the ridge elongation is found to be 2.5 time higher than the one on the parallel. This amplification is found to be independent of the shaking intensity (PGV). But we show that it strongly depends on the parameter α defined as the angle between the azimuth of incoming wave and the azimuth of the ridge divide.


    African Journals Online (AJOL)

    ES Obe


    driven rotating horizontal short shaft which is connected by universal joints to two gangs of rotary hoe weeders. With the short shaft nearly at the bottom of a furrow between two ridges, the gangs of weeders lie on the sides of ...

  17. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)


    This Remedial Investigation (RI) Work Plan specifically addresses Chestnut Ridge Operable Unit 1, (OU1) which consists of the Chestnut Ridge Security Pits (CRSP). The CRSP are located {approximately}800 ft southeast of the central portion of the Y-12 Plant atop Chestnut Ridge, which is bounded to the northwest by Bear Creek Valley and to the southeast by Bethel Valley. Operated from 1973 to 1988, the CRSP consisted of a series of trenches used for the disposal of classified hazardous and nonhazardous waste materials. Disposal of hazardous waste materials was discontinued in December 1984, while nonhazardous waste disposal ended on November 8, 1988. An RI is being conducted at this site in response to CERCLA regulations. The overall objectives of the RI are to collect data necessary to evaluate the nature and extent of contaminants of concern (COC), support an ecological risk assessment (ERA) and a human health risk assessment (HHRA), support the evaluation of remedial alternatives, and ultimately develop a Record of Decision for the site. The purpose of this Work Plan is to outline RI activities necessary to define the nature and extent of suspected contaminants at Chestnut Ridge OU1. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the overall risk posed to human health and the environment by OU1.

  18. Efficiency of local surface plasmon polariton excitation on ridges

    DEFF Research Database (Denmark)

    Radko, Ilya; Bozhevolnyi, Sergey I.; Boltasseva, Alexandra


    We investigate experimentally and numerically the efficiency of surface plasmon polariton excitation by a focused laser beam using gold ridges. The dependence of the efficiency on geometrical parameters of ridges and wavelength dependence are examined. The experimental measurements accomplished...

  19. NPP Tropical Forest: John Crow Ridge, Jamaica, 1974-1978 (United States)

    National Aeronautics and Space Administration — ABSTRACT: Biomass and productivity for four subtypes of an upper montane tropical forest along John Crow Ridge in the Blue Ridge Mountains of Jamaica from 1974 to 1978

  20. Photoreflectance Characterization of Semiconductors (United States)

    Bhimnathwala, Hemant Ghanshyamdas

    Photoreflectance technique has been used as a non-destructive probe of surface photo-voltage in doped and semi-insulating semiconductors. A system used to measure the photoreflectance spectra near the fundamental gap of GaAs and InP has been described. Measurements as a function of pump intensity on n and p type GaAs were used to infer the carrier dynamics leading to change in the surface electric field. Measurements indicate that the surface of GaAs consists of hole traps at the surface in addition to recombination states. This is confirmed by spectroscopic studies carried out by varying the pump modulation frequency at fixed temperatures and the measurements show that the hole trap has an activation energy of 0.29 eV and has an emission time of 0.175 +/- 0.002 msec. at room temperature. In semi-insulating GaAs, it is expected that there is no surface electric field at equilibrium due to pinning at the surface and large concentration of deep defect EL2. Electromodulation, in this case proceeds via preferential trapping of holes at the surface. This is supported by measurements carried out as a function of pump intensity and on wafers having different carbon concentrations. Analysis of carrier dynamics in semi-insulating GaAs is much simplified by use of Nd:YAG laser (instead of a HeNe laser) as a source of pump beam. A sub-band -gap excitation generates mainly excess electrons and the Poisson's equation can be integrated once to find the surface electric field. Numerical integration yields the surface photovoltage. It is shown that this technique is sensitive to the the surface state density and relatively insensitive to bulk properties. It has been applied to study the effect of various chemical reactants on the surface state density. In many PR spectra, features at energies less than the gap energy are observed. These are ascribed to shallow acceptors unrelated to carbon, which was the dominant acceptor in these materials. It is proposed that the electric field

  1. Physics of semiconductor laser devices

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, G.H.B.


    The physics of the semiconductor laser is studied. The basic phenomena that control the operation of the device are analyzed and described in considerable detail. The treatment has been keyed particularly to fundamental concepts and kept general in order to avoid being overtaken by events. The range of phenomena in a semiconductor laser involves a number of scientific disciplines. To cater for the reader who is not already a specialist in all of these the author has endeavoured, in the chapters on fundamental behaviour, to provide in a readable form the minimum background that is needed to understand the more specialist part of the text. As an introduction a general review is given of the whole range of semiconductor laser devices that now exist, the technology involved in their fabrication, the factors that determine their reliability, and their possible role in integrated systems.

  2. Thiophene-Based Organic Semiconductors. (United States)

    Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan


    Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

  3. High pressure semiconductor physics I

    CERN Document Server

    Willardson, R K; Paul, William; Suski, Tadeusz


    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise indeed that this tra...

  4. The structural aspects of the flabby ridge or alveolar fibrosis.


    Thevissen, E; VANSTEENBERGHE, D; Lambrecht, Johan; CREEMERS, Julia; Vandenabeele, Frank


    A flabby ridge or alveolar fibrosis is a dcnture-induced change of the oral mucosa. The flabby ridge originates when parts of the alveolar ridge becomes resorbed duc to excessive occlusal trauma on she denture in the affected area. In this case dlsc oral mucosa at the level of the flabby ridgc was studied using light microscopy, electron microscopy and inununohaislochemistry. The structures were compared with the normal oral mucosa of the maxilla. The flabby ridge was surgic...

  5. Semiconductor device physics and simulation

    CERN Document Server

    Yuan, J S


    This volume provides thorough coverage of modern semiconductor devices -including hetero- and homo-junction devices-using a two-dimensional simulator (MEDICI) to perform the analysis and generate simulation results Each device is examined in terms of dc, ac, and transient simulator results; relevant device physics; and implications for design and analysis Two hundred forty-four useful figures illustrate the physical mechanisms and characteristics of the devices simulated Comprehensive and carefully organized, Semiconductor Device Physics and Simulation is the ideal bridge from device physics to practical device design

  6. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher


    The developments with coherent control (CC) techniques in optical spectroscopy have recently demonstrated population control and coherence manipulations when the induced optical phase is explored with phase-locked laser pulses. These and other developments have been guiding the new research field...... of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase-locked...

  7. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry


    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  8. Semiconductors and semimetals epitaxial microstructures

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Gossard, Arthur C


    Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

  9. Introduction to semiconductor manufacturing technology

    CERN Document Server


    IC chip manufacturing processes, such as photolithography, etch, CVD, PVD, CMP, ion implantation, RTP, inspection, and metrology, are complex methods that draw upon many disciplines. [i]Introduction to Semiconductor Manufacturing Technologies, Second Edition[/i] thoroughly describes the complicated processes with minimal mathematics, chemistry, and physics; it covers advanced concepts while keeping the contents accessible to readers without advanced degrees. Designed as a textbook for college students, this book provides a realistic picture of the semiconductor industry and an in-depth discuss

  10. Wide band gap semiconductor templates

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Stan, Liliana (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); DePaula, Raymond F. (Santa Fe, NM); Usov, Igor O. (Los Alamos, NM)


    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  11. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  12. Organic semiconductors in sensor applications

    CERN Document Server

    Malliaras, George; Owens, Róisín


    Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

  13. Does the lateral intercondylar ridge disappear in ACL deficient patients?

    NARCIS (Netherlands)

    van Eck, C.F.; Martins, C.A.Q.; Vyas, S.M.; Celentano, U.; van Dijk, C.N.; Fu, F.H.


    The aim of this study was to determine whether there is a difference in the presence of the lateral intercondylar ridge and the lateral bifurcate ridge between patients with sub-acute and chronic ACL injuries. We hypothesized that the ridges would be present less often with chronic ACL deficiency.

  14. Influence of phonons on semiconductor quantum emission

    Energy Technology Data Exchange (ETDEWEB)

    Feldtmann, Thomas


    A microscopic theory of interacting charge carriers, lattice vibrations, and light modes in semiconductor systems is presented. The theory is applied to study quantum dots and phonon-assisted luminescence in bulk semiconductors and heterostructures. (orig.)

  15. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y


    Provides detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. This textbook emphasizes understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors and features an extensive collection of tables of material parameters, figures, and problems.

  16. Applications of semiconductor detectors to nuclear medicine

    CERN Document Server

    Bradford-Barber, H


    Progress in the development of semiconductor detectors is being applied to improving the resolution and imaging performance of nuclear medicine cameras. Nuclear medicine is briefly described. Efforts to develop semiconductor cameras for both planar and tomographic imaging are reviewed.

  17. The Greenland-Iceland-Faroe Ridge Complex (United States)

    Erlendsson, Ögmundur; Hjartarson, Árni; Blischke, Anett


    The Greenland-Iceland-Faroe Ridge Complex GIFRC covers 480.000 km2 of a thick volcanic crust that stretches 1150 km across the central Northeast Atlantic Ocean between the central East Greenland and the Northwest European margins. It incorporates the Iceland plateau, the aseismic Greenland-Iceland ridge, and the Iceland-Faroe ridge. GIFRC has been in development since the opening of the NE-Atlantic around 55 Ma. It appears as a prominent feature in all geological and geophysical data sets. Synclines and anticlines in the area will be summarised and, among others, several new ones that were revealed in seismic reflection data near to Iceland. Specifically, the offshore anticlines and synclines may be related to old rift systems prior the forming of Iceland as an insular shelf region (>24 Ma). Synclines are suggested to be manifestations of former rift axes that have been abandoned by rift jumps. These rift jumps appear to be more common inside the GIFRC region than in the ocean basins south and north of the area. They can be confirmed by the observation of cumulative crustal accretion through time as well. The GIFRC represents a complex region of crustal accretion in 3 dimensions due to overlapping rift systems, complex interlinked rift and transform zones, and several unconformities that suggest a variable uplift and subsidence history for the ridge complex. An excellent example to visualise such processes of vertical crustal accretion and rift jumps is seen in seismic reflection data that extends along the southwestern slope of the Iceland-Faroe Ridge. They clearly display the internal structures of basement blocks, separated by a syncline and younger rift system, and the formation of an anticline across the deeply buried basement blocks that are overlain by seaward dipping reflectors (SDR). We suggest a major hiatus (40 Ma - 24-20 Ma) and a related unconformity at the boundary of the volcanic insular shelf edge of East Iceland and the Faroe Ridge, buried beneath

  18. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.


    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...

  19. Towards filament free semiconductor lasers

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter; Skovgaard, Peter M. W.


    We outline physical models and simulations for suppression of self-focusing and filamentation in large aperture semiconductor lasers. The principal technical objective is to generate multi-watt CW or quasi-CW outputs with nearly diffraction limited beams, suitable for long distance free space...... propagation structures in lasers and amplifiers which suppress lateral reflections....

  20. Semiconductors for plasmonics and metamaterials

    DEFF Research Database (Denmark)

    Naik, G.V.; Boltasseva, Alexandra


    Plasmonics has conventionally been in the realm of metal-optics. However, conventional metals as plasmonic elements in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals with semiconduct...

  1. 2010 Defects in Semiconductors GRC

    Energy Technology Data Exchange (ETDEWEB)

    Shengbai Zhang


    Continuing its tradition of excellence, this Gordon Conference will focus on research at the forefront of the field of defects in semiconductors. The conference will have a strong emphasis on the control of defects during growth and processing, as well as an emphasis on the development of novel defect detection methods and first-principles defect theories. Electronic, magnetic, and optical properties of bulk, thin film, and nanoscale semiconductors will be discussed in detail. In contrast to many conferences, which tend to focus on specific semiconductors, this conference will deal with point and extended defects in a broad range of electronic materials. This approach has proved to be extremely fruitful for advancing fundamental understanding in emerging materials such as wide-band-gap semiconductors, oxides, sp{sup 2} carbon based-materials, and photovoltaic/solar cell materials, and in understanding important defect phenomena such as doping bottleneck in nanostructures and the diffusion of defects and impurities. The program consists of about twenty invited talks and a number of contributed poster sessions. The emphasis should be on work which has yet to be published. The large amount of discussion time provides an ideal forum for dealing with topics that are new and/or controversial.

  2. Atomistic Models of Amorphous Semiconductors

    NARCIS (Netherlands)

    Jarolimek, K.


    Crystalline silicon is probably the best studied material, widely used by the semiconductor industry. The subject of this thesis is an intriguing form of this element namely amorphous silicon. It can contain a varying amount of hydrogen and is denoted as a-Si:H. It completely lacks the neat long

  3. Growth of a tectonic ridge during the Landers earthquake (United States)

    Fleming, R.W.; Johnson, A.M.


    The formation of tectonic ridges by localized vertical uplift along strike-slip faults has long been suspected, but the actual growth of a tectonic ridge during an earthquake has never been documented. During the 1992 Landers, California, earthquake sequence, an awl-shaped, dome-like topographic ridge along the Emerson fault zone increased its height at least 1 m concurrently with 3 m of right-lateral shift across the fault zone containing the ridge. Five deformation vectors within the ridge reveal dilatant behavior in addition to the uplift and shift on boundary faults.

  4. Basic semiconductor physics. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Hamaguchi, Chihiro [Osaka Univ., Suita (Japan). Dept. Electronic Engineering


    This book presents a detailed description of the basic semiconductor physics. The reader is assumed to have a basic command of mathematics and some elementary knowledge of solid state physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. The reader can understand three different methods of energy band calculations, empirical pseudo-potential, k.p perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for full band Monte Carlo simulation are discussed. Experiments and theoretical analysis of cyclotron resonance are discussed in detail because the results are essential to the understanding of semiconductor physics. Optical and transport properties, magneto-transport, two dimensional electron gas transport (HEMT and MOSFET), and quantum transport are reviewed, explaining optical transition, electron phonon interactions, electron mobility. Recent progress in quantum structures such as two-dimensional electron gas, superlattices, quantum Hall effect, electron confinement and the Landauer formula are included. The Quantum Hall effect is presented with different models. In the second edition, the addition energy and electronic structure of a quantum dot (artificial atom) are explained with the help of Slater determinants. Also the physics of semiconductor Lasers is described in detail including Einstein coefficients, stimulated emission, spontaneous emission, laser gain, double heterostructures, blue Lasers, optical confinement, laser modes, strained quantum wells lasers which will give insight into the physics of various kinds of semiconductor lasers, in addition to the various processes of luminescence. (orig.)

  5. Oak Ridge 25-MV tandem accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, N.F.; Richardson, E.G.; Mann, J.E.; Juras, R.C.; Jones, C.M.; Biggerstaff, J.A.; Benjamin, J.A.


    A new heavy-ion accelerator facility is nearing completion at the Oak Ridge National Laboratory. This paper presents a brief description of the scope and status of this project and a discussion of some aspects of the first operational experience with the 25 MV tandem accelerator which is being provided by the National Electrostatics Corporation (NEC) as a major component of the first phase of the facility.

  6. Oak Ridge National Laboratory Waste Management Plan

    Energy Technology Data Exchange (ETDEWEB)


    The objective of the Oak Ridge National Laboratory Waste Management Plan is to compile and to consolidate information annually on how the ORNL Waste Management Program is conducted, which waste management facilities are being used to manage wastes, what forces are acting to change current waste management systems, what activities are planned for the forthcoming fiscal year (FY), and how all of the activities are documented.

  7. ORNL (Oak Ridge National Laboratory) 89

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.D.; Appleton, B.R.; Jefferson, J.W.; Merriman, J.R.; Mynatt, F.R.; Richmond, C.R.; Rosenthal, M.W.


    This is the inaugural issues of an annual publication about the Oak Ridge National Laboratory. Here you will find a brief overview of ORNL, a sampling of our recent research achievements, and a glimpse of the directions we want to take over the next 15 years. A major purpose of ornl 89 is to provide the staff with a sketch of the character and dynamics of the Laboratory.

  8. Global survey of lunar wrinkle ridge formation times (United States)

    Yue, Z.; Michael, G. G.; Di, K.; Liu, J.


    Wrinkle ridges are a common feature of the lunar maria and record subsequent contraction of mare infill. Constraining the timing of wrinkle ridge formation from crater counts is challenging because they have limited areal extent and it is difficult to determine whether superposed craters post-date ridge formation or have alternatively been uplifted by the deformation. Some wrinkle ridges do allow determination to be made. This is possible where a ridge shows a sufficiently steep boundary or scarp that can be identified as deforming an intersecting crater or the crater obliterates the relief of the ridge. Such boundaries constitute only a small fraction of lunar wrinkle ridge structures yet they are sufficiently numerous to enable us to obtain statistically significant crater counts over systems of structurally related wrinkle ridges. We carried out a global mapping of mare wrinkle ridges, identifying appropriate boundaries for crater identification, and mapping superposed craters. Selected groups of ridges were analyzed using the buffered crater counting method. We found that, except for the ridges in mare Tranquilitatis, the ridge groups formed with average ages between 3.5 and 3.1 Ga ago, or 100-650 Ma after the oldest observable erupted basalts where they are located. We interpret these results to suggest that local stresses from loading by basalt fill are the principal agent responsible for the formation of lunar wrinkle ridges, as others have proposed. We find a markedly longer interval before wrinkle ridge formation in Tranquilitatis which likely indicates a different mechanism of stress accumulation at this site.

  9. Utilization of high resolution satellite gravity over the Carlsberg Ridge (United States)

    Chatterjee, S.; Bhattacharyya, R.; Majumdar, T. J.


    The Carlsberg Ridge lies between the equator and the Owen fracture zone. It is the most prominent mid-ocean ridge segment of the western Indian Ocean, which contains a number of earthquake epicenters. Satellite altimetry can be used to infer subsurface geological structures analogous to gravity anomaly maps generated through ship-borne survey. In this study, free-air gravity and its 3D image have been generated over the Carlsberg Ridge using a very high resolution data base, as obtained from Geosat GM, ERS-1, Seasat and TOPEX/POSEIDON altimeter data. As observed in this study, the Carlsberg Ridge shows a slow spreading characteristic with a deep and wide graben (average width ˜15 km). The transform fault spacing confirms variable slow to intermediate characteristics with first and second order discontinuities. The isostatically compensated region of the Carlsberg Ridge could be demarcated with near zero contour values in the free-air gravity anomaly images over and along the Carlsberg Ridge axes and over most of the fracture zone patterns. Few profiles have been generated across the Carlsberg Ridge and the characteristics of slow/intermediate spreading ridge of various orders of discontinuity could be identified. It has also been observed in zero contour image as well as in the characteristics of valley patterns along the ridge from NW to SE that different spreading rates, from slow to intermediate, are occurring in different parts of the Carlsberg ridge. It maintains the morphology of a slow spreading ridge in the NW, where the wide and deep axial valley (˜1.5 3 km) also implies the pattern of a slow spreading ridge. However, a change in the morphology/depth of the axial valley from NW to SE indicates the nature of the Carlsberg Ridge as a slow to intermediate spreading ridge.

  10. Processing of Oak Ridge Mixed Waste Labpacks

    Energy Technology Data Exchange (ETDEWEB)

    Estes, C. H.; Franco, P.; Bisaria, A.


    The Oak Ridge Site Treatment Plan (STP) issued under a Tennessee Commissioner's Order includes a compliance milestone related to treatment of mixed waste labpacks on the Oak Ridge sites. The treatment plan was written and approved in Fiscal Year 1997. The plan involved approximately 1,100 labpacks and 7,400 on-the-shelf labpackable items stored at three Department of Energy (DOE) sites on the Oak Ridge Reservation (ORR). The labpacks and labpack items consist of liquids and solids with various chemical constituents and radiological concerns. The waste must be processed for shipment to a commercial hazardous waste treatment facility or treatment utilizing a Broad Spectrum mixed waste treatment contract. This paper will describe the labpack treatment plan that was developed as required by the Site Treatment Plan and the operations implemented to process the labpack waste. The paper will discuss the labpack inventory in the treatment plan, treatment and disposal options, processing strategies, project risk assessment, and current project status.

  11. Microbial life in ridge flank crustal fluids. (United States)

    Huber, Julie A; Johnson, H Paul; Butterfield, David A; Baross, John A


    To determine the microbial community diversity within old oceanic crust, a novel sampling strategy was used to collect crustal fluids at Baby Bare Seamount, a 3.5 Ma old outcrop located in the north-east Pacific Ocean on the eastern flank of the Juan de Fuca Ridge. Stainless steel probes were driven directly into the igneous ocean crust to obtain samples of ridge flank crustal fluids. Genetic signatures and enrichment cultures of microorganisms demonstrate that these crustal fluids host a microbial community composed of species indigenous to the subseafloor, including anaerobic thermophiles, and species from other deep-sea habitats, such as seawater and sediments. Evidence using molecular techniques indicates the presence of a relatively small but active microbial population, dominated by bacteria. The microbial community diversity found in the crustal fluids may indicate habitat variability in old oceanic crust, with inputs of nutrients from seawater, sediment pore-water fluids and possibly hydrothermal sources. This report further supports the presence of an indigenous microbial community in ridge flank crustal fluids and advances our understanding of the potential physiological and phylogenetic diversity of this community.

  12. Semiconductor detectors in nuclear and particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Rehak, P. [Brookhaven National Lab., Upton, NY (United States); Gatti, E. [Piazza Leonardo da Vinci 32, Milano (Italy)


    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups: Classical semiconductor diode detectors and semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported.

  13. Semiconductor detectors in nuclear and particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Rehak, P. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Gatti, E. [Politecnico di Milano, Dipartimento di Elletronica e Informazione, Piazza Leondardo da Vinci 32, 20133 Milano (Italy)


    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups; (i) classical semiconductor diode detectors and (ii) semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities. (United States)

    Wei, Hai-Rui; Deng, Fu-Guo


    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.

  15. Sensing operations based on hexagonal GaN microdisks acting as whispering-gallery mode optical microcavities. (United States)

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


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

  16. Low-threshold Raman laser from an on-chip, high-Q, polymer-coated microcavity. (United States)

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


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

  17. Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect

    CERN Document Server

    Yüce, Emre; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L


    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities operating in the "original" telecom band by exploiting the instantaneous electronic Kerr effect. We demonstrate that resonance frequency reversibly shifts within a picosecond and the magnitude of the shift is affected by the backbone of the $\\lambda-$layer. We investigate experimentally and theoretically the role of the quality factor in terms of its effect on resonance frequency shift. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the cavity cavity storage time is matched. Our experiments and our calculations indicate that the resonance frequency shift induced via the electronic Kerr effect can be maximized by judicious tuning of the pump frequency, pump power and pump pulse duration relative to the storage time of the cavity.

  18. Combined long-period grating and micro-cavity in-line Mach-Zehnder interferometer for refractive index sensing (United States)

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


    This work presents combined long-period grating (LPG) and a micro-cavity in-line Mach-Zehnder interferometer (μIMZI), both induced in the same single-mode optical fiber. In order to increase refractive index (RI) sensitivity of the LPG, it has been nanocoated with aluminum oxide (Al2O3). Next, the μIMZI has been fabricated as a cylindrical cavity (d = 60 μm) in the center of the LPG. In transmission measurements for various RI in the cavity and around the LPG we have observed two effects coming from two independently working sensors. There was no significant impact on one or the other in terms of their functional properties. Such a combination of sensorial effects can be applied for cross-reference measurements of the two different parameters at the same time or for discrimination of influence of other parameters on the RI measurements.

  19. Versatile Implementation in Angle-Resolved Optical Microscopy: Its Application to Local Spectrometry of Microcavities with PIC-J-Aggregates

    Directory of Open Access Journals (Sweden)

    Yuki Obara


    Full Text Available Versatile novel implementations in microspectroscopy are developed, which can provide angle-resolved optical spectroscopy at local sample areas almost in diffraction limit. By selecting focus position of light flux incident within the back focal plane of the objective lens radially from the position of the optical axis of the microscope with employing off-centered pinhole, we can obtain parallel beam with oblique incidence and its angle tuning at the sample surface. In this paper, we describe our specific optical setup and its practical working principle in detail. We report, as a demonstration of its performance, our latest studies on optical properties of cavity polariton states in the so-called quantum microcavity structures, which contain molecular J-aggregates of pseudoisocyanine (PIC dye as active working materials. By using the microscope technique, we obtain a fair amount of improvement in the linewidth observation of cavity polariton spectra.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chakravarty, Swapnajit, E-mail:; Hosseini, Amir; Xu, Xiaochuan [Omega Optics, Inc., Austin, Texas 78757 (United States); Zhu, Liang; Zou, Yi [Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78758 (United States); Chen, Ray T., E-mail: [Omega Optics, Inc., Austin, Texas 78757 (United States); Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78758 (United States)


    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.

  1. Axial seamount: An active ridge axis volcano on the Central Juan De Fuca Ridge (United States)

    Johnson, H. Paul; Embley, Robert W.


    Axial Seamount (some of the manuscripts in this special section refer to the edifice with the more precise name of "Axial Volcano"), a large ridge axis volcano, is located on the central segment of the Juan de Fuca Ridge approximately 250 nautical miles west of the Washington/Oregon/British Columbia coast. Currently both volcanically and hydrothermally active, Axial lies directly at the intersection of the Cobb-Eickelberg Seamount Chain and the Juan de Fuca Ridge (Figure 1). The volcanic activity associated with the seamount formation strongly interacts with, and is affected by, the normal seafloor spreading processes at the intersection. Because of this unique geologic setting, its proximity to west coast ports and oceanographie institutions, and its shallow depth, Axial has become the focus of a large number of scientific investigations over the past decade.

  2. Spectroscopic analysis of optoelectronic semiconductors

    CERN Document Server

    Jimenez, Juan


    This book deals with standard spectroscopic techniques which can be used to analyze semiconductor samples or devices, in both, bulk, micrometer and submicrometer scale. The book aims helping experimental physicists and engineers to choose the right analytical spectroscopic technique in order to get specific information about their specific demands. For this purpose, the techniques including technical details such as apparatus and probed sample region are described. More important, also the expected outcome from experiments is provided. This involves also the link to theory, that is not subject of this book, and the link to current experimental results in the literature which are presented in a review-like style. Many special spectroscopic techniques are introduced and their relationship to the standard techniques is revealed. Thus the book works also as a type of guide or reference book for people researching in optical spectroscopy of semiconductors.

  3. Catalysts, Protection Layers, and Semiconductors

    DEFF Research Database (Denmark)

    Chorkendorff, Ib


    acid or alkaline conditions. Since most relevant semiconductors are very prone to corrosion the advantage of using buried junctions and using protection layers offering shall be discussed [2-4]. Next we shall discuss the availability of various catalysts for being coupled to these protections layers...... and how their stability may be evaluated [5, 6]. Examples of half-cell reaction using protection layers for both cathode and anode will be discussed though some of recent examples under both alkaline and acidic conditions. Si is a very good low band gap semiconductor and by using TiO2 as a protection...... layer we can stabilize it for both H2 and O2 evolution [7, 8, 9, 10]. Notably NiOx promoted by iron is a material that is transparent, providing protection, and is a good catalyst for O2 evolution. We have also recently started searching for large band gap semicondutors like III-V based or pervoskite...

  4. Transversal light forces in semiconductors

    CERN Document Server

    Lindberg, M


    The transversal light force is a well established effect in atomic and molecular systems that are exposed to spatially inhomogeneous light fields. In this paper it is shown theoretically that in an excited semiconductor, containing an electron-hole plasma or excitons, a similar light force exists, if the semiconductor is exposed to an ultrashort spatially inhomogeneous light field. The analysis is based on the equations of motion for the Wigner distribution functions of charge carrier populations and interband polarizations. The results show that, while the light force on the electron-hole plasma or the excitons does exist, its effects on the kinetic behaviour of the electron-hole plasma or the excitons are different compared to the situation in an atomic or molecular system. A detailed analysis presented here traces this difference back to the principal differences between atoms and molecules on the one hand and electron-hole plasmas or excitons on the other hand.

  5. Semiconductor electrolyte photovoltaic energy converter (United States)

    Anderson, W. W.; Anderson, L. B.


    Feasibility and practicality of a solar cell consisting of a semiconductor surface in contact with an electrolyte are evaluated. Basic components and processes are detailed for photovoltaic energy conversion at the surface of an n-type semiconductor in contact with an electrolyte which is oxidizing to conduction band electrons. Characteristics of single crystal CdS, GaAs, CdSe, CdTe and thin film CdS in contact with aqueous and methanol based electrolytes are studied and open circuit voltages are measured from Mott-Schottky plots and open circuit photo voltages. Quantum efficiencies for short circuit photo currents of a CdS crystal and a 20 micrometer film are shown together with electrical and photovoltaic properties. Highest photon irradiances are observed with the GaAs cell.

  6. Hypersonic modes in nanophononic semiconductors. (United States)

    Hepplestone, S P; Srivastava, G P


    Frequency gaps and negative group velocities of hypersonic phonon modes in periodically arranged composite semiconductors are presented. Trends and criteria for phononic gaps are discussed using a variety of atomic-level theoretical approaches. From our calculations, the possibility of achieving semiconductor-based one-dimensional phononic structures is established. We present results of the location and size of gaps, as well as negative group velocities of phonon modes in such structures. In addition to reproducing the results of recent measurements of the locations of the band gaps in the nanosized Si/Si{0.4}Ge{0.6} superlattice, we show that such a system is a true one-dimensional hypersonic phononic crystal.

  7. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa


    of a novel epitaxial structure design. The layered structure is based on chirping the barrier layer thickness of the over grown quantum dash layer, in a multi-stack quantum dash/barrier active region, with the aim of inducing additional inhomogeneity. Based on material-structure and device characterization, enhanced lasing-emission bandwidth is achieved from the narrow (2 u m)ridge-waveguide LDs as a result of the formation of multiple ensembles of quantum dashes that are electronically different, in addition to improved device performance. Moreover, realization of SLDs from this device structure demonstrated extra-ordinary emission bandwidth covering the entire international telecommunication union (O- to U-) bands. This accomplishment is a collective emission from quantum wells and quantum dashes of the device active region. All these results lead to a step forward in the eventual realization of more than 150 nm lasing bandwidth from a single semiconductor laser diode.

  8. Volcanism and hydrothermalism on a hotspot-influenced ridge: Comparing Reykjanes Peninsula and Reykjanes Ridge, Iceland (United States)

    Pałgan, Dominik; Devey, Colin W.; Yeo, Isobel A.


    Current estimates indicate that the number of high-temperature vents (one of the primary pathways for the heat extraction from the Earth's mantle) - at least 1 per 100 km of axial length - scales with spreading rate and should scale with crustal thickness. But up to present, shallow ridge axes underlain by thick crust show anomalously low incidences of high-temperature activity. Here we compare the Reykjanes Ridge, an abnormally shallow ridge with thick crust and only one high-temperature vent known over 900 km axial length, to the adjacent subaerial Reykjanes Peninsula (RP), which is characterized by high-temperature geothermal sites confined to four volcanic systems transected by fissure swarms with young (Holocene) volcanic activity, multiple faults, cracks and fissures, and continuous seismic activity. New high-resolution bathymetry (gridded at 60 m) of the Reykjanes Ridge between 62°30‧N and 63°30‧N shows seven Axial Volcanic Ridges (AVR) that, based on their morphology, geometry and tectonic regime, are analogues for the volcanic systems and fissure swarms on land. We investigate in detail the volcano-tectonic features of all mapped AVRs and show that they do not fit with the previously suggested 4-stage evolution model for AVR construction. Instead, we suggest that AVR morphology reflects the robust or weak melt supply to the system and two (or more) eruption mechanisms may co-exist on one AVR (in contrast to 4-stage evolution model). Our interpretations indicate that, unlike on the Reykjanes Peninsula, faults on and around AVRs do not cluster in orientation domains but all are subparallel to the overall strike of AVRs (orthogonal to spreading direction). High abundance of seamounts shows that the region centered at 62°47‧N and 25°04‧W (between AVR-5 and -6) is volcanically robust while the highest fault density implies that AVR-1 and southern part of AVR-6 rather undergo period of melt starvation. Based on our observations and interpretations we

  9. Identification of defects in semiconductors

    CERN Document Server

    Stavola, Michael; Weber, Eicke R; Stavola, Michael


    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors.The"Willardson and Beer"Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices,Oxygen in Silicon, and others promise indeed that this traditi...

  10. Ballistic superconductivity in semiconductor nanowires. (United States)

    Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K; van Veen, Jasper; de Moor, Michiel W A; Bommer, Jouri D S; van Woerkom, David J; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Quintero-Pérez, Marina; Cassidy, Maja C; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P


    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices.

  11. Fabry-Pérot microcavity modes observed in the micro-photoluminescence spectra of the single nanowire with InGaAs/GaAs heterostructure. (United States)

    Yang, Lin; Motohisa, Junichi; Fukui, Takashi; Jia, Lian Xi; Zhang, Lei; Geng, Ming Min; Chen, Pin; Liu, Yu Liang


    We report on the fabrication of the nanowires with InGaAs/GaAs heterostructures on the GaAs(111)B substrate using selective-area metal organic vapor phase epitaxy. Fabry-Pérot microcavity modes were observed in the nanowires with perfect end facets dispersed onto the silicon substrate and not observed in the free-standing nanowires. We find that the calculated group refractive indices only considering the material dispersion do not agree with the experimentally determined values although this method was used by some researchers. The calculated group refractive indices considering both the material dispersion and the waveguide dispersion agree with the experimentally determined values well. We also find that Fabry-Pérot microcavity modes are not observable in the nanowires with the width less than about 180 nm, which is mainly caused by their poor reflectivity at the end facets due to their weak confinement to the optical field.

  12. Phase shift multiplication effect of all-optical analog to electromagnetically induced transparency in two micro-cavities side coupled to a waveguide system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Boyun; Wang, Tao, E-mail:; Tang, Jian; Li, Xiaoming; Dong, Chuanbo [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)


    We propose phase shift multiplication effect of all-optical analog to electromagnetically induced transparency in two photonic crystal micro-cavities side coupled to a waveguide system through external optical pump beams. With dynamically tuning the propagation phase of the line waveguide, the phase shift of the transmission spectrum in two micro-cavities side coupled to a waveguide system is doubled along with the phase shift of the line waveguide. π-phase shift and 2π-phase shift of the transmission spectrum are obtained when the propagation phase of the line waveguide is tuned to 0.5π-phase shift and π-phase shift, respectively. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and the coupled-mode formalism. These results show a new direction to the miniaturization and the low power consumption of microstructure integration photonic devices in optical communication and quantum information processing.

  13. Enhanced Ferromagnetism in Nanoscale GaN:Mn Wires Grown on GaN Ridges. (United States)

    Cheng, Ji; Jiang, Shengxiang; Zhang, Yan; Yang, Zhijian; Wang, Cunda; Yu, Tongjun; Zhang, Guoyi


    The problem of weak magnetism has hindered the application of magnetic semiconductors since their invention, and on the other hand, the magnetic mechanism of GaN-based magnetic semiconductors has been the focus of long-standing debate. In this work, nanoscale GaN:Mn wires were grown on the top of GaN ridges by metalorganic chemical vapor deposition (MOCVD), and the superconducting quantum interference device (SQUID) magnetometer shows that its ferromagnetism is greatly enhanced. Secondary ion mass spectrometry (SIMS) and energy dispersive spectroscopy (EDS) reveal an obvious increase of Mn composition in the nanowire part, and transmission electron microscopy (TEM) and EDS mapping results further indicate the correlation between the abundant stacking faults (SFs) and high Mn doping. When further combined with the micro-Raman results, the magnetism in GaN:Mn might be related not only to Mn concentration, but also to some kinds of built-in defects introduced together with the Mn doping or the SFs.

  14. Enhanced Ferromagnetism in Nanoscale GaN:Mn Wires Grown on GaN Ridges

    Directory of Open Access Journals (Sweden)

    Ji Cheng


    Full Text Available The problem of weak magnetism has hindered the application of magnetic semiconductors since their invention, and on the other hand, the magnetic mechanism of GaN-based magnetic semiconductors has been the focus of long-standing debate. In this work, nanoscale GaN:Mn wires were grown on the top of GaN ridges by metalorganic chemical vapor deposition (MOCVD, and the superconducting quantum interference device (SQUID magnetometer shows that its ferromagnetism is greatly enhanced. Secondary ion mass spectrometry (SIMS and energy dispersive spectroscopy (EDS reveal an obvious increase of Mn composition in the nanowire part, and transmission electron microscopy (TEM and EDS mapping results further indicate the correlation between the abundant stacking faults (SFs and high Mn doping. When further combined with the micro-Raman results, the magnetism in GaN:Mn might be related not only to Mn concentration, but also to some kinds of built-in defects introduced together with the Mn doping or the SFs.

  15. Microsurgical treatment of medial sphenoid ridge meningioma

    Directory of Open Access Journals (Sweden)

    Wei-qi HE


    Full Text Available Objective To explore the microsurgical technique of medial sphenoid ridge meningioma resectional therapy.Methods The clinical data were retrospectively analyzed of 29 patients(13 males and 16 females;aged 18-68 years with average of 42 years;duration of disease was 5 months to 8 years,averaged 28 months with medial sphenoidal ridge meningioma and admitted from Jan.2005 to Jan.2010.The anatomical relationship of the tumor to surrounding structures was assessed intraoperatively,the tumor was then completely resected through cutting off the tumor supplying vessels,shrinking the tumor volume and separating the tumors from adjacent vessels and nerves.All the patients were followed up for 4 months to 4 years.Results Of the 29 cases,20 got total tumor removal,7 got subtotal and 2 got partial tumor removal.Of the 20 patients with obviously preoperative visual impairment,12 were obviously relieved,6 showed no improvement and 2 got symptoms aggravation.Hemiplegia occurred in 2 cases and oculomoter nerve palsy in 6 cases.There was no death after surgery.A 6 months to 4 years follow-up showed that no recurrence was found in 27 patients with tumor resection level of Simpson I and II,2 patients with tumor resection level of Simpson III received postoperative radiotherapy or gamma knife surgery,and 1 recurred and received reoperation.Conclusions Fine intraoperative assessment of the anatomical relationship of the tumor to surrounding structures,separating and excising tumor according to the assessed result is the key of medial sphenoid ridge meningioma resection,and the tumor resection is favorable to visual rehabilitation and tumor control.

  16. Oak Ridge TNS Program: a status report

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M


    The Oak Ridge TNS activities have been directed at characterizing the design space between TFTR and EPR with a fundamental emphasis on higher beta plasma systems than previously projected, i.e., anti ..beta.. approximately 5 to 10% as compared to 1 to 3%. Based on the results of the FY 1977 System Studies, our activities this year are directed toward preconceptual design with particular emphasis placed on reducing the technological requirements through innovations in plasma engineering. Examples of the new innovations include microwave assisted start up to reduce power requirements and a reduced TF ripple constraint by more refined ripple loss calculations, to increase engineering feasibility through simpler, more maintainable designs.

  17. Oak Ridge Leadership Computing Facility Position Paper

    Energy Technology Data Exchange (ETDEWEB)

    Oral, H Sarp [ORNL; Hill, Jason J [ORNL; Thach, Kevin G [ORNL; Podhorszki, Norbert [ORNL; Klasky, Scott A [ORNL; Rogers, James H [ORNL; Shipman, Galen M [ORNL


    This paper discusses the business, administration, reliability, and usability aspects of storage systems at the Oak Ridge Leadership Computing Facility (OLCF). The OLCF has developed key competencies in architecting and administration of large-scale Lustre deployments as well as HPSS archival systems. Additionally as these systems are architected, deployed, and expanded over time reliability and availability factors are a primary driver. This paper focuses on the implementation of the Spider parallel Lustre file system as well as the implementation of the HPSS archive at the OLCF.

  18. Environmental baseline survey report for West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge and parcel 21D in the vicinity of the East Technology Park, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    King, David A. [Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States). Independent Environmental Assessment and Verification Program


    This environmental baseline survey (EBS) report documents the baseline environmental conditions of five land parcels located near the U.S. Department of Energy?s (DOE?s) East Tennessee Technology Park (ETTP), including West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge, and Parcel 21d. Preparation of this report included the detailed search of federal government records, title documents, aerial photos that may reflect prior uses, and visual inspections of the property and adjacent properties. Interviews with current employees involved in, or familiar with, operations on the real property were also conducted to identify any areas on the property where hazardous substances and petroleum products, or their derivatives, and acutely hazardous wastes may have been released or disposed. In addition, a search was made of reasonably obtainable federal, state, and local government records of each adjacent facility where there has been a release of any hazardous substance or any petroleum product or their derivatives, including aviation fuel and motor oil, and which is likely to cause or contribute to a release of any hazardous substance or any petroleum product or its derivatives, including aviation fuel or motor oil, on the real property. A radiological survey and soil/sediment sampling was conducted to assess baseline conditions of Parcel 21d that were not addressed by the soils-only no-further-investigation (NFI) reports. Groundwater sampling was also conducted to support a Parcel 21d decision. Based on available data West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, and West Pine Ridge are not impacted by site operations and are not subject to actions per the Federal Facility Agreement (FFA). This determination is supported by visual inspections, records searches and interviews, groundwater conceptual modeling, approved NFI reports, analytical data, and risk analysis results. Parcel 21d data, however, demonstrate impacts from site

  19. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)



    The Oak Ridge Comprehensive Integrated Plan is intended to assist the US Department of Energy (DOE) and contractor personnel in implementing a comprehensive integrated planning process consistent with DOE Order 430.1, Life Cycle Asset Management and Oak Ridge Operations Order 430. DOE contractors are charged with developing and producing the Comprehensive Integrated Plan, which serves as a summary document, providing information from other planning efforts regarding vision statements, missions, contextual conditions, resources and facilities, decision processes, and stakeholder involvement. The Comprehensive Integrated Plan is a planning reference that identifies primary issues regarding major changes in land and facility use and serves all programs and functions on-site as well as the Oak Ridge Operations Office and DOE Headquarters. The Oak Ridge Reservation is a valuable national resource and is managed on the basis of the principles of ecosystem management and sustainable development and how mission, economic, ecological, social, and cultural factors are used to guide land- and facility-use decisions. The long-term goals of the comprehensive integrated planning process, in priority order, are to support DOE critical missions and to stimulate the economy while maintaining a quality environment.

  20. Transition between bulk and surface refractive index sensitivity of micro-cavity in-line Mach-Zehnder interferometer induced by thin film deposition. (United States)

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


    In this work we discuss the refractive index (RI) sensitivity of a micro-cavity in-line Mach-Zehnder interferometer in the form of a cylindrical hole (40-50 μm in diameter) fabricated in a standard single-mode optical fiber using a femtosecond laser. The surface of the micro-cavity was coated with up to 400 nm aluminum oxide thin film using the atomic layer deposition method. Next, the film was progressively chemically etched and the influence on changes in the RI of liquid in the micro-cavity was determined at different stages of the experiment, i.e., at different thicknesses of the film. An effect of transition between sensitivity to the film thickness (surface) and the RI of liquid in the cavity (bulk) is demonstrated for the first time. We have found that depending on the interferometer working conditions determined by thin film properties, the device can be used for investigation of phenomena taking place at the surface, such as in case of specific label-free biosensing applications, or for small-volume RI analysis as required in analytical chemistry.

  1. From tides to mixing along the Hawaiian ridge. (United States)

    Rudnick, Daniel L; Boyd, Timothy J; Brainard, Russell E; Carter, Glenn S; Egbert, Gary D; Gregg, Michael C; Holloway, Peter E; Klymak, Jody M; Kunze, Eric; Lee, Craig M; Levine, Murray D; Luther, Douglas S; Martin, Joseph P; Merrifield, Mark A; Moum, James N; Nash, Jonathan D; Pinkel, Robert; Rainville, Luc; Sanford, Thomas B


    The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure.

  2. 75 FR 49526 - Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor... (United States)


    ... Employment and Training Administration Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor, Inc., Technical Information Center, Woburn, MA; Amended Certification Regarding... to Apply for Worker Adjustment Assistance on October 1, 2009, applicable to workers of Freescale...

  3. Multiple expressions of plume-ridge interaction at the Galapagos: Volcanic lineaments and ridge jumps (United States)

    Mittelstaedt, E. L.; Soule, S. A.; Harpp, K. S.; Fornari, D. J.


    Despite significant evidence for communication between an upwelling mantle plume beneath the Galápagos Archipelago (GA) and the nearby Galápagos Spreading Center (GSC), little is known about the dynamics of the interaction between the ridge and the hotspot. We use new bathymetry, sidescan sonar, magnetic, subbottom seismic, and gravity data from the FLAMINGO cruise (MV1007) to address the mechanism of plume-ridge interaction in the Northern Galápagos Volcanic Province (NGVP), a region centered on the 90° 50'W Galápagos transform fault (GTF). West of the GTF, the Nazca Plate is dominated by numerous seamounts aligned in 3 volcanic lineaments. Volumetrically, the lineaments are composed of ~1500 km3 of erupted lavas. Faulting patterns and seamount elongations suggest that the locations and orientations of the lineaments may be partly controlled by the lithospheric stress field. In contrast, east of the GTF on the Cocos Plate, there is little evidence of constructional volcanism (~69 km3). However, we observe several linear, nearly ridge-parallel, faulted features separating sediment-filled basins, and two large bathymetric highs with up to 1km of relief. Differences in seafloor west and east of the GTF are also observed in the Residual Mantle Bouguer Anomaly (RMBA). On the Nazca Plate, RMBA lows closely contour the volcanic lineaments with minima at the centers of the largest volcanoes along the Wolf-Darwin Lineament. On the Cocos Plate, the RMBA at a given distance from the ridge axis is generally more negative than at similar locations on the Nazca Plate. In addition, two RMBA lows are observed coincident with the observed bathymetric highs, both of which are slightly elongate in a direction sub-parallel to the Eastern GSC, possibly reflecting a period of increased magma flux along a former ridge axis. Magnetic anomalies reveal a complicated history of plate evolution including a series of ridge jumps since ~3 Ma that result in creation of the GTF. We invert

  4. Electronic properties of semiconductor surfaces and metal/semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, M.


    This thesis reports investigations of the electronic properties of a semiconductor surface (silicon carbide), a reactive metal/semiconductor interface (manganese/silicon) and a non-reactive metal/semiconductor interface (aluminum-magnesium alloy/silicon). The (2 x 1) reconstruction of the 6H-SiC(0001) surface has been obtained by cleaving the sample along the (0001) direction. This reconstruction has not been observed up to now for this compound, and has been compared with those of similar elemental semiconductors of the fourth group of the periodic table. This comparison has been carried out by making use of photoemission spectroscopy, analyzing the core level shifts of both Si 2p and C 1s core levels in terms of charge transfer between atoms of both elements and in different chemical environments. From this comparison, a difference between the reconstruction on the Si-terminated and the C-terminated surface was established, due to the ionic nature of the Si-C bond. The growth of manganese films on Si(111) in the 1-5 ML thickness range has been studied by means of LEED, STM and photoemission spectroscopy. By the complementary use of these surface science techniques, two different phases have been observed for two thickness regimes (<1 ML and >1 ML), which exhibit a different electronic character. The two reconstructions, the (1 x 1)-phase and the ({radical}3 x {radical}3)R30 -phase, are due to silicide formation, as observed in core level spectroscopy. The growth proceeds via island formation in the monolayer regime, while the thicker films show flat layers interrupted by deep holes. On the basis of STM investigations, this growth mode has been attributed to strain due to lattice mismatch between the substrate and the silicide. Co-deposition of Al and Mg onto a Si(111) substrate at low temperature (100K) resulted in the formation of thin alloy films. By varying the relative content of both elements, the thin films exhibited different electronic properties

  5. Emission and Absorption Entropy Generation in Semiconductors


    Reck, Kasper; Varpula, Aapo; Prunnila, Mika; Hansen, Ole


    While emission and absorption entropy generation is well known in black bodies, it has not previously been studied in semiconductors, even though semiconductors are widely used for solar light absorption in modern solar cells [1]. We present an analysis of the entropy generation in semiconductor materials due to emission and absorption of electromagnetic radiation. It is shown that the emission and absorption entropy generation reduces the fundamental limit on the efficiency of any semiconduc...

  6. Hybridization at superconductor-semiconductor interfaces


    Mikkelsen, August E. G.; Kotetes, Panagiotis; Krogstrup, Peter; Flensberg, Karsten


    Hybrid superconductor-semiconductor devices are currently one of the most promising platforms for realizing Majorana zero modes. We address the role of band bending and superconductor-semiconductor hybridization in such devices by analyzing a gated single Al-InAs interface using a self-consistent Schroedinger-Poisson approach. Our numerical analysis shows that the band bending leads to an interface quantum well, which localizes the charge in the system near the superconductor-semiconductor in...

  7. Semiconductor power devices physics, characteristics, reliability

    CERN Document Server

    Lutz, Josef; Scheuermann, Uwe; De Doncker, Rik


    Semiconductor power devices are the heart of power electronics. They determine the performance of power converters and allow topologies with high efficiency. Semiconductor properties, pn-junctions and the physical phenomena for understanding power devices are discussed in depth. Working principles of state-of-the-art power diodes, thyristors, MOSFETs and IGBTs are explained in detail, as well as key aspects of semiconductor device production technology. In practice, not only the semiconductor, but also the thermal and mechanical properties of packaging and interconnection technologies are esse

  8. Toward a national semiconductor strategy, volume 1 (United States)


    Updated here are key market data showing trends in the U.S. semiconductor industry's world market position. New information is given on three emerging semiconductor-based technologies: broadband communications, advanced display systems, and intelligent vehicles and highways. These are examples of important, high-volume markets that will consume significant numbers of semiconductor components and that must be addressed in a national semiconductor strategy. New recommendations and a summary of all Committee recommendations to date are given as well as a summary of comments received at a public forum held in Silicon Valley in may 1990.

  9. Comparison of buried sand ridges and regressive sand ridges on the outer shelf of the East China Sea (United States)

    Wu, Ziyin; Jin, Xianglong; Zhou, Jieqiong; Zhao, Dineng; Shang, Jihong; Li, Shoujun; Cao, Zhenyi; Liang, Yuyang


    Based on multi-beam echo soundings and high-resolution single-channel seismic profiles, linear sand ridges in U14 and U2 on the East China Sea (ECS) shelf are identified and compared in detail. Linear sand ridges in U14 are buried sand ridges, which are 90 m below the seafloor. It is presumed that these buried sand ridges belong to the transgressive systems tract (TST) formed 320-200 ka ago and that their top interface is the maximal flooding surface (MFS). Linear sand ridges in U2 are regressive sand ridges. It is presumed that these buried sand ridges belong to the TST of the last glacial maximum (LGM) and that their top interface is the MFS of the LGM. Four sub-stage sand ridges of U2 are discerned from the high-resolution single-channel seismic profile and four strikes of regressive sand ridges are distinguished from the submarine topographic map based on the multi-beam echo soundings. These multi-stage and multi-strike linear sand ridges are the response of, and evidence for, the evolution of submarine topography with respect to sea-level fluctuations since the LGM. Although the difference in the age of formation between U14 and U2 is 200 ka and their sequences are 90 m apart, the general strikes of the sand ridges are similar. This indicates that the basic configuration of tidal waves on the ECS shelf has been stable for the last 200 ka. A basic evolutionary model of the strata of the ECS shelf is proposed, in which sea-level change is the controlling factor. During the sea-level change of about 100 ka, five to six strata are developed and the sand ridges develop in the TST. A similar story of the evolution of paleo-topography on the ECS shelf has been repeated during the last 300 ka.

  10. Behavior of Cell on Vibrating Micro Ridges

    Directory of Open Access Journals (Sweden)

    Haruka Hino


    Full Text Available The effect of micro ridges on cells cultured at a vibrating scaffold has been studied in vitro. Several parallel lines of micro ridges have been made on a disk of transparent polydimethylsiloxane for a scaffold. To apply the vibration on the cultured cells, a piezoelectric element was attached on the outside surface of the bottom of the scaffold. The piezoelectric element was vibrated by the sinusoidal alternating voltage (Vp-p < 16 V at 1.0 MHz generated by a function generator. Four kinds of cells were used in the test: L929 (fibroblast connective tissue of C3H mouse, Hepa1-6 (mouse hepatoma, C2C12 (mouse myoblast, 3T3-L1 (mouse fat precursor cells. The cells were seeded on the micro pattern at the density of 2000 cells/cm2 in the medium containing 10% FBS (fetal bovine serum and 1% penicillin/ streptomycin. After the adhesion of cells in several hours, the cells are exposed to the ultrasonic vibration for several hours. The cells were observed with a phase contrast microscope. The experimental results show that the cells adhere, deform and migrate on the scaffold with micro patterns regardless of the ultrasonic vibration. The effects of the vibration and the micro pattern depend on the kind of cells.

  11. Z-contrast imaging and grain boundaries in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chisholm, M.F.; Pennycook, S.J.


    Interest in grain boundaries in semiconductors is linked to the application of polycrystalline semiconductors as photovoltaic and interconnect materials. In real devices such as solar cells and MOS structures as well as future devices such as flat-panel displays, the intergranular regions of the polycrystalline solid have a significant effect on the flow of electronic current. These grain boundary barriers exist because the chemical potential of the boundary atoms are shifted from the bulk value by the change in local symmetry. The chemical potential is also changed by impurities, other structural defects, and other phases in the boundary. The lack of knowledge on the atomic structure of grain boundaries is, at present, the greatest barrier to advancements in the understanding of the electrical properties of these defects. The advances of the last few years have provided the tools with which to probe these interfaces at the true atomic scale. One such tool is the high-resolution scanning transmission electron microscope installed at Oak Ridge National Laboratory (VG Microscopes HB603) that can form a 1.27 {Angstrom} electron probe. Images are formed by scanning the probe across a thin sample and using an annular detector to collect electrons scattered to high angles. Because the annular detector collects electrons scattered over a wide range of angles, phase correlation and dynamical diffraction effects are averaged by this annular integration. Thus, an image with incoherent characteristics is produced and retained to relatively large specimen thickness. The key advantage of incoherent imaging is that when the microscope is focused to produce maximum image contrast, the bright image features directly correspond to the positions of the atomic columns.

  12. Microradiography with Semiconductor Pixel Detectors (United States)

    Jakubek, Jan; Cejnarova, Andrea; Dammer, Jiří; Holý, Tomáš; Platkevič, Michal; Pospíšil, Stanislav; Vavřík, Daniel; Vykydal, Zdeněk


    High resolution radiography (with X-rays, neutrons, heavy charged particles, …) often exploited also in tomographic mode to provide 3D images stands as a powerful imaging technique for instant and nondestructive visualization of fine internal structure of objects. Novel types of semiconductor single particle counting pixel detectors offer many advantages for radiation imaging: high detection efficiency, energy discrimination or direct energy measurement, noiseless digital integration (counting), high frame rate and virtually unlimited dynamic range. This article shows the application and potential of pixel detectors (such as Medipix2 or TimePix) in different fields of radiation imaging.

  13. Optoelectronic properties of semiconductor nanostructures (United States)

    Maher, Kristin Nicole

    Semiconductor nanostructures have unique optical and electronic properties that have inspired research into their technological applications and basic science. This thesis presents approaches to the fabrication and characterization of optoelectronic devices incorporating individual semiconductor nanostructures. Nanowires of the II-VI semiconductors CdSe and CdS were synthesized using nanoparticle-catalysed solution-liquid-solid growth. Single-component nanowires and heterostructure nanowires with axial compositional modulation were generated using this method. Individual nanowires and nanocrystals were then incorporated into devices with a three-terminal field-effect transistor geometry. An experimental platform was developed which allows for simultaneous electrical characterization of devices and measurement of their optical properties. This setup enables the measurement of spatially and spectrally resolved electroluminescence (EL) and photoluminescence (PL) from individual nanostructures and nanostructure devices. It also allows the measurement of photon coincidence histograms for emitted light and the acquisition of photocurrent images via laser scanning microscopy. Electroluminescence was observed from individual CdSe nanocrystals contacted by gold electrodes. Concomitant transport measurements at low temperature showed clear evidence of Coulomb blockade at low bias voltage, with light only emitted from devices exhibiting asymmetric tunnel couplings between the nanocrystal and electrodes. Combined analyses of the data indicate that the resistances of the tunnel barriers are bias voltage dependent and that light emission results from the inelastic scattering of tunneling electrons. Three-terminal devices incorporating individual CdSe nanoNvires exhibited EL localized near the positively-biased electrode. Characterization of these devices by scanning photocurrent microscopy (SPCM) and Kelvin probe microscopy (KPM) indicates that while there are n-type Schottky

  14. Optic probe for semiconductor characterization (United States)

    Sopori, Bhushan L [Denver, CO; Hambarian, Artak [Yerevan, AM


    Described herein is an optical probe (120) for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe (120) detects laser light reflected from the surface (124) of the wafer (106) within various ranges of angles. Characteristics of defects in the surface (124) of the wafer (106) are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system (100) is described that includes the described optical probe (120).

  15. Trace analysis of semiconductor materials

    CERN Document Server

    Cali, J Paul; Gordon, L


    Trace Analysis of Semiconductor Materials is a guidebook concerned with procedures of ultra-trace analysis. This book discusses six distinct techniques of trace analysis. These techniques are the most common and can be applied to various problems compared to other methods. Each of the four chapters basically includes an introduction to the principles and general statements. The theoretical basis for the technique involved is then briefly discussed. Practical applications of the techniques and the different instrumentations are explained. Then, the applications to trace analysis as pertaining

  16. Electronic Properties of Semiconductor Interfaces. (United States)


    AD-A130 745 ELECTRONIC PROPERTIES OF SEMICONDUCTOR INTERFACES(U) /; UNIVERSIDAD AUfONOMA DE MADRID (SPAIN) DEPT DE FISICA DEL ESTADO SOLIDO F FLORES...Estado Solido 6.11.02A Universidad Autonoma Cantoblanco, Madrid 34. Spain 1T161102BH57-03 11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE...different supe4layeru formed by the superlayers (0,1), (2,3), (4,5),... and so on. Note that the number of super - layers defined inside each 6upettayer

  17. Processing of insulators and semiconductors (United States)

    Quick, Nathaniel R.; Joshi, Pooran C.; Duty, Chad Edward; Jellison, Jr., Gerald Earle; Angelini, Joseph Attilio


    A method is disclosed for processing an insulator material or a semiconductor material. The method includes pulsing a plasma lamp onto the material to diffuse a doping substance into the material, to activate the doping substance in the material or to metallize a large area region of the material. The method may further include pulsing a laser onto a selected region of the material to diffuse a doping substance into the material, to activate the doping substance in the material or to metallize a selected region of the material.

  18. Semiconductor-Based Nanotechnology Applications (United States)


    as SnO2 , ZnO, and CeO2, reported in 40 refereed research papers. In this ARO project, studies on ultra small particles of these oxides with...semiconductors such as SnO2 , ZnO, and CeO2, reported in 40 refereed research papers. In this ARO project, studies on ultra small particles of these oxides...ferromagnetism. Thin film structures using Co doped SnO2 were fabricated and studied their usefulness in device applications. NP of semiconducting oxides such

  19. Dual modulation of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Gorfinkel, V.B. [Univ. of Kassel (Germany); Luryi, S. [AT and T Bell Labs., Murray Hill, NJ (United States)


    Large signal analysis of dual modulation of semiconductor lasers (by a simultaneous high-frequency control of the pumping current I and an additional intrinsic parameter) shows that the method allows suppressing the relaxation oscillations for an arbitrary shape of the pumping current signal I (t). Because of that, the rate of information coding can be enhanced to about 80 Gbit/sec. Moreover, the authors demonstrate that dual modulation allows to maintain a linear relationship between I (t) and the output optical power in a wide frequency band.

  20. Carslberg Ridge and Mid-Atlantic Ridge: Slow-spreading Apparent Analogs (United States)

    Rona, P. A.; Murton, B. J.; Bostrom, K.; Widenfalk, L.; Melson, W. G.; O'Hearn, T.; Cronan, D. S.; Jenkins, W. J.


    We compare morphology, tectonics, petrology, and hydrothermal activity of a known section of the Mid-Atlantic Ridge (MAR) between the Kane and Atlantis fracture zones (full multi-beam coverage 21N to 31N) to the lesser known Carlsberg Ridge (CR; limited multi-beam coverage plus satellite altimetry). The CR extends from the Owen Fracture Zone (10N) to the Vityaz Fracture Zone (5S) and spreads at half-rates (~1.2-1.8 cm/yr) similar to the MAR: 1) Morphology: Both ridges exhibit distinct segmentation (primarily sinistral) and axial valleys with high floor to crest relief (range 1122-1771 m). Average lengths of segments (CR: 70 km; MAR: 50 km) and crest-to crest width of the axial valley are greater on the CR (40 km) than MAR (23 km). Axial volcanic ridges form the neovolcanic zone on both ridges, typically 2.6 km wide and 213 m high on the CR. Average water depth near segment centers is greater on the MAR (3933 m) than the CR (3564 m). V-shaped patterns oblique to the spreading axis are present on both ridges. 2) Tectonics: Segments on each ridge are predominantly separated by short-offset (faults generally spaced hundreds of kilometers apart. Bulls-eye Mantle Bouguer Lows (-30 to -50 mgal) are present at centers of spreading segments on both ridges. Metamorphic core complexes of lower crust and upper mantle are present on the MAR section (at fracture zones) and at least at one locality at 58.33E on the CR. 3) Petrology: MORB composition from our 20 stations along the CR fall into the MORB family, with no evidence of hotspot inputs (no excess K or Nb), or extreme fractionation, similar to the MAR section. REE and trace element patterns between 57E and 61E on the CR indicate increasing melt depletion to the northwest, while glasses exhibit a striking systematic increase in MgO (decrease in fractionation) to the northwest and attain among the most primitive composition of any ocean ridge adjacent to the Owen fracture zone (9.93wt percent). Sr, Nd, and Pb isotopic

  1. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    van Wanum, Maurice; Lebouille, Tom; Visser, Guido; van Vliet, Frank Edward


    Abstract In this article diodes from three different semiconductor technologies are compared based on their suitability to protect a receiver. The semiconductor materials involved are silicon, gallium arsenide and gallium nitride. The diodes in the diverse semiconductor technologies themselves are

  2. 60 Years of Great Science (Oak Ridge National Laboratory) (United States)


    This issue of Oak Ridge National Laboratory Review (vol. 36, issue 1) highlights Oak Ridge National Laboratory's contributions in more than 30 areas of research and related activities during the past 60 years and provides glimpses of current activities that are carrying on this heritage.

  3. A relook into the crustal architecture of Laxmi Ridge, northeastern ...

    Indian Academy of Sciences (India)

    derived free-air gravity (FAG) data to derive the crustal structure of Laxmi Ridge and adjacent areas. 2D and 3D crustal modelling suggests that the high resolution FAG low associated with the ridge is due to underplating and that it is of ...

  4. Some improved classification-based ridge parameter of Hoerl and ...

    African Journals Online (AJOL)

    In a linear regression model, it is often assumed that the explanatory variables are independent. This assumption is often violated and Ridge Regression estimator introduced by [2]has been identified to be more efficient than ordinary least square (OLS) in handling it. However, it requires a ridge parameter, K, of which many ...

  5. Some Improved Classification-Based Ridge Parameter Of Hoerl And ...

    African Journals Online (AJOL)

    In a linear regression model, it is often assumed that the explanatory variables are independent. This assumption is often violated and Ridge Regression estimator introduced by [2]has been identified to be more efficient than ordinary least square (OLS) in handling it. However, it requires a ridge parameter, K, of which many ...

  6. The Incidence of Finger Ridge Counts among the Christian ...

    African Journals Online (AJOL)


    Abstract - The present study was attempted to obtain the occurrence total and absolute finger ridge counts from 102 unrelated Christian populations (60 males and 42 females) of Mysore city, Karnataka state of India. Data were collected by biometric scanner (USB finger print reader). The mean values of Total finger ridge ...

  7. Structure and origin of the 85 degrees E ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Ramana, M.V.; Subrahmanyam, V.; Chaubey, A.K.; Ramprasad, T.; Sarma, K.V.L.N.S.; Krishna, K.S.; Desa, M.; Murty, G.P.S.; Subrahmanyam, C.

    that the rocks of the 85 degrees E Ridge are magnetized with revesed polarity. The well-defined geophysical anomalies and and lack of magnetic polarity reversals together with the deep burial nature of the ridge may not favor a hotspot origin. Two alternative...

  8. Modeling the dynamics of offshore tidal sand ridges

    NARCIS (Netherlands)

    Yuan, B.


    Tidal sand ridges are large-scale bedforms with horizontal dimensions of several kilometers and heights of tens of meters. They occur in the offshore area of shelf seas that have a wide range of water depths (10-200 m). Based on their present-day behavior, ridges are classified as `active' (sand

  9. Oak Ridge Reservation Annual Site environmental report summary for 1994

    Energy Technology Data Exchange (ETDEWEB)



    This document presents a summary of the information collected for the Oak Ridge Reservation 1994 site environmental report. Topics discussed include: Oak Ridge Reservation mission; ecology; environmental laws; community participation; environmental restoration; waste management; radiation effects; chemical effects; risk to public; environmental monitoring; and radionuclide migration.

  10. Development of a Ridge Profile Weeder | Odigboh | Nigerian ...

    African Journals Online (AJOL)

    The prototype weeder described in this paper consists of a ground-driven rotating horizontal short shaft which is connected by universal joints to two gangs of rotary hoe weeders. With the short shaft nearly at the bottom of a furrow between two ridges, the gangs of weeders lie on the sides of the two ridges. The universal ...

  11. Semiconductor nanostructures for artificial photosynthesis (United States)

    Yang, Peidong


    Nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have already been demonstrated as important materials for different energy conversion. One emerging and exciting direction is their application for solar to fuel conversion. The generation of fuels by the direct conversion of solar energy in a fully integrated system is an attractive goal, but no such system has been demonstrated that shows the required efficiency, is sufficiently durable, or can be manufactured at reasonable cost. One of the most critical issues in solar water splitting is the development of a suitable photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of direct solar water splitting.

  12. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn


    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  13. Terahertz semiconductor-heterostructure laser. (United States)

    Köhler, Rüdeger; Tredicucci, Alessandro; Beltram, Fabio; Beere, Harvey E; Linfield, Edmund H; Davies, A Giles; Ritchie, David A; Iotti, Rita C; Rossi, Fausto


    Semiconductor devices have become indispensable for generating electromagnetic radiation in everyday applications. Visible and infrared diode lasers are at the core of information technology, and at the other end of the spectrum, microwave and radio-frequency emitters enable wireless communications. But the terahertz region (1-10 THz; 1 THz = 10(12) Hz) between these ranges has remained largely underdeveloped, despite the identification of various possible applications--for example, chemical detection, astronomy and medical imaging. Progress in this area has been hampered by the lack of compact, low-consumption, solid-state terahertz sources. Here we report a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure. The prototype demonstrated emits a single mode at 4.4 THz, and already shows high output powers of more than 2 mW with low threshold current densities of about a few hundred A cm(-2) up to 50 K. These results are very promising for extending the present laser concept to continuous-wave and high-temperature operation, which would lead to implementation in practical photonic systems.

  14. Modeling of semiconductor nanostructures and semiconductor-electrolyte interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Birner, Stefan


    The main objective of Part I is to give an overview of some of the methods that have been implemented into the nextnano{sup 3} software. Examples are discussed that give insight into doping, strain and mobility. Applications of the single-band Schroedinger equation include three-dimensional superlattices, and a qubit that is manipulated by a magnetic field. Results of the multi-band k.p method are presented for HgTe-CdTe and InAs-GaSb superlattices, and for a SiGe-Si quantum cascade structure. Particular focus is put on a detailed description of the contact block reduction (CBR) method that has been developed within our research group. By means of this approach, quantum transport in the ballistic limit in one, two and three dimensions can be calculated. I provide a very detailed description of the algorithm and present several well documented examples that highlight the key points of this method. Calculating quantum transport in three dimensions is a very challenging task where computationally efficient algorithms - apart from the CBR method - are not available yet. Part II describes the methods that I have implemented into the nextnano{sup 3} software for calculating systems that consist of a combination of semiconductor materials and liquids. These biosensors have a solid-electrolyte interface, and the charges in the solid and in the electrolyte are coupled to each other through the Poisson-Boltzmann equation. I apply this model to a silicon based protein sensor, where I solve the Schroedinger equation together with the Poisson-Boltzmann equation self-consistently, and compare theoretical results with experiment. Furthermore, I have developed a novel approach to model the charge density profiles at semiconductor-electrolyte interfaces that allows us to distinguish hydrophobic and hydrophilic interfaces. Our approach extends previous work where ion specific potentials of mean force describe the distribution of ion species at the interface. I apply this new model

  15. Revisiting the Ridge-Push Force Using the Lithospheric Geoid (United States)

    Richardson, R. M.; Coblentz, D. D.


    The geoid anomaly and driving force associated with the cooling oceanic lithosphere ("ridge push") are both proportional to dipole moment of the density-depth distribution, and allow a reevaluation of the ridge push force using the geoid. The challenge with this approach is to isolate the "lithospheric geoid" from the full geoid signal. Our approach is to use a band-pass spherical harmonic filter on the full geoid (e.g., EGM2008-WGS84, complete to spherical harmonic degree and order 2159) between orders 6 and 80. However, even this "lithospheric geoid" is noisy, and thus we average over 100 profiles evenly spaced along the global ridge system to obtain an average geoid step associated with the mid-ocean ridges. Because the positive ridge geoid signal is largest near the ridge (and to capture fast-spreading ridges), we evaluate symmetrical profiles extending ±45 m.y. about the ridge. We find an average ridge geoid anomaly of 4.5m, which is equivalent to a 10m anomaly for 100 m.y. old oceanic lithosphere. This geoid step corresponds to a ridge push force of ~2.4 x1012N/m for old oceanic lithosphere of 100 m.y., very similar to earlier estimates of ~2.5 x1012N/m based on simple half-space models. This simple half-space model also predicts constant geoid slopes of about 0.15 m/m.y. for cooling oceanic lithosphere. Our observed geoid slopes are consistent with this value for ages up to 40-50 m.y., but drop off to lower values at greater ages. We model this using a plate cooling model (with a thickness of the order of 125km) to fit the observation that the geoid anomaly and ridge driving force only increase slowly for ages greater than 40 m.y. (in contrast to the half-space model where the linear dependence on age holds for all ages). This reduction of the geoid slope results in a 20% decrease in the predicted ridge push force. This decrease is due to the combined effects of treating the oceanic lithosphere as a cooling plate (vs. a half-space), and the loss of geoidal

  16. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)


    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous

  17. New semiconductor materials for magnetoelectronics at room ...

    Indian Academy of Sciences (India)

    Most of the semiconductor materials are diamagnetic by nature and therefore cannot take active part in the operation of the magneto electronic devices. In order to enable them to be useful for such devices a recent effort has been made to develop diluted magnetic semiconductors (DMS) in which small quantity of magnetic ...

  18. Epitaxy of semiconductor-superconductor nanowires

    DEFF Research Database (Denmark)

    Krogstrup, P.; Ziino, N.L.B.; Chang, W.


    Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface...

  19. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry


    We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  20. Semiconductor composition containing iron, dysprosium, and terbium

    Energy Technology Data Exchange (ETDEWEB)

    Pooser, Raphael C.; Lawrie, Benjamin J.; Baddorf, Arthur P.; Malasi, Abhinav; Taz, Humaira; Farah, Annettee E.; Kalyanaraman, Ramakrishnan; Duscher, Gerd Josef Mansfred; Patel, Maulik K.


    An amorphous semiconductor composition includes 1 to 70 atomic percent iron, 15 to 65 atomic percent dysprosium, 15 to 35 atomic percent terbium, balance X, wherein X is at least one of an oxidizing element and a reducing element. The composition has an essentially amorphous microstructure, an optical transmittance of at least 50% in at least the visible spectrum and semiconductor electrical properties.

  1. Packaging of high power semiconductor lasers

    CERN Document Server

    Liu, Xingsheng; Xiong, Lingling; Liu, Hui


    This book introduces high power semiconductor laser packaging design. The characteristics and challenges of the design and various packaging, processing, and testing techniques are detailed by the authors. New technologies, in particular thermal technologies, current applications, and trends in high power semiconductor laser packaging are described at length and assessed.

  2. neutron-Induced Failures in semiconductor Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wender, Stephen Arthur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Single Event Effects are a very significant failure mode in modern semiconductor devices that may limit their reliability. Accelerated testing is important for semiconductor industry. Considerable more work is needed in this field to mitigate the problem. Mitigation of this problem will probably come from Physicists and Electrical Engineers working together

  3. Optical dating of dune ridges on Rømø

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, A. S.; Andersen, Thorbjørn Joest


    The application of optically stimulated luminescence (OSL) to the dating of recent aeolian sand ridges on Rømø, an island off the southwest coast of Denmark, is tested. These sand ridges began to form approximately 300 years ago, and estimates of the ages are available from historical records....... Samples for OSL dating were taken ~0.5 m below the crests of four different dune ridges; at least five samples were recovered from each ridge to test the internal consistency of the ages. Additional samples were recovered from the low lying areas in the swales and from the scattered dune formations......-defined building phases separated by inactive periods and the first major ridge formed ~235 years ago. This study demonstrates that optical dating can be successfully applied to these young aeolian sand deposits, and we conclude that OSL dating is a powerful chronological tool in studies of coastal change....

  4. The fate of volatiles in mid-ocean ridge magmatism

    CERN Document Server

    Keller, Tobias; Hirschmann, Marc M


    Deep-Earth volatile cycles couple the mantle with near-surface reservoirs. Volatiles are emitted by volcanism and, in particular, from mid-ocean ridges, which are the most prolific source of basaltic volcanism. Estimates of volatile extraction from the asthenosphere beneath ridges typically rely on measurements of undegassed lavas combined with simple petrogenetic models of the mean degree of melting. Estimated volatile fluxes have large uncertainties; this is partly due to a poor understanding of how volatiles are transported by magma in the asthenosphere. Here, we assess the fate of mantle volatiles through numerical simulations of melting and melt transport at mid-ocean ridges. Our simulations are based on two-phase, magma/mantle dynamics theory coupled to an idealised thermodynamic model of mantle melting in the presence of water and carbon dioxide. We combine simulation results with catalogued observations of all ridge segments to estimate a range of likely volatile output from the global mid-ocean ridge...

  5. Oak Ridge Reservation environmental report for 1989

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, V.A.; Wilson, A.R. (eds.)


    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1989. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1989 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1. 16 figs., 194 tabs.

  6. Oak Ridge Health Studies phase 1 report, Volume 1: Oak Ridge Phase 1 overview

    Energy Technology Data Exchange (ETDEWEB)

    Yarbrough, M.I.; Van Cleave, M.L.; Turri, P.; Daniel, J.


    In July 1991, the State of Tennessee initiated the Health Studies Agreement with the United States Department of Energy to carry out independent studies of possible adverse health effects in people living in the vicinity of the Oak Ridge Reservation. The health studies focus on those effects that could have resulted or could result from exposures to chemicals and radioactivity released at the Reservation since 1942. The major focus of the first phase was to complete a Dose Reconstruction Feasibility Study. This study was designed to find out if enough data exist about chemical and radionuclide releases from the Oak Ridge Reservation to conduct a second phase. The second phase will lead to estimates of the actual amounts or the ``doses`` of various contaminants received by people as a result of off-site releases. Once the doses of various contaminants have been estimated, scientists and physicians will be better able to evaluate whether adverse health effects could have resulted from the releases.

  7. Melton Valley Storage Tanks Capacity Increase Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)



    The US Department of Energy (DOE) proposes to construct and maintain additional storage capacity at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, for liquid low-level radioactive waste (LLLW). New capacity would be provided by a facility partitioned into six individual tank vaults containing one 100,000 gallon LLLW storage tank each. The storage tanks would be located within the existing Melton Valley Storage Tank (MVST) facility. This action would require the extension of a potable water line approximately one mile from the High Flux Isotope Reactor (HFIR) area to the proposed site to provide the necessary potable water for the facility including fire protection. Alternatives considered include no-action, cease generation, storage at other ORR storage facilities, source treatment, pretreatment, and storage at other DOE facilities.

  8. Source document for waste area groupings at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, P.L.; Kuhaida, A.J., Jr.


    This document serves as a source document for Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and other types of documents developed for and pertaining to Environmental Restoration (ER) Program activities at Oak Ridge National Laboratory (ORNL). It contains descriptions of the (1) regulatory requirements for the ORR ER Program, (2) Oak Ridge Reservation (ORR) ER Program, (3) ORNL site history and characterization, and (4) history and characterization of Waste Area Groupings (WAGS) 1-20. This document was created to save time, effort, and money for persons and organizations drafting documents for the ER Program and to improve consistency in the documents prepared for the program. By eliminating the repetitious use of selected information about the program, this document will help reduce the time and costs associated with producing program documents. By serving as a benchmark for selected information about the ER Program, this reference will help ensure that information presented in future documents is accurate and complete.

  9. Molecular semiconductors photoelectrical properties and solar cells

    CERN Document Server

    Rees, Ch


    During the past thirty years considerable efforts have been made to design the synthesis and the study of molecular semiconductors. Molecular semiconductors - and more generally molecular materials - involve interactions between individual subunits which can be separately synthesized. Organic and metallo-organic derivatives are the basis of most of the molecular materials. A survey of the literature on molecular semiconductors leaves one rather confused. It does seem to be very difficult to correlate the molecular structure of these semiconductors with their experimental electrical properties. For inorganic materials a simple definition delimits a fairly homogeneous family. If an inorganic material has a conductivity intermediate between that of an 12 1 1 3 1 1 insulator « 10- n- cm- ) and that of a metal (> 10 n- cm- ), then it is a semiconductor and will exhibit the characteristic properties of this family, such as junction formation, photoconductivity, and the photovoltaic effect. For molecular compounds,...

  10. Physics of semiconductor devices (2nd edition)

    Energy Technology Data Exchange (ETDEWEB)

    Sze, S.M.


    A resume is presented regarding the physics and properties of semiconductors, taking into account aspects of crystal structure, the energy bands, the carrier concentration at thermal equilibrium, carrier transport phenomena, basic equations for semiconductor device operation, and phonon spectra and optical, thermal, and high-field properties of semiconductors. The bipolar devices considered include the p-n junction diode, the bipolar transistor, and thyristors. Unipolar devices are discussed, taking into account metal-semiconductor contacts, JFET and MESFET, the MIS diode and CCD, and MOSFET. A description is provided of special microwave devices, giving attention to tunnel devices, IMPATT and related transit-time diodes, and transferred-electron devices. Photonic devices investigated include LED and semiconductor lasers, photodetectors, and solar cells.

  11. Device Physics of Narrow Gap Semiconductors

    CERN Document Server

    Chu, Junhao


    Narrow gap semiconductors obey the general rules of semiconductor science, but often exhibit extreme features of these rules because of the same properties that produce their narrow gaps. Consequently these materials provide sensitive tests of theory, and the opportunity for the design of innovative devices. Narrow gap semiconductors are the most important materials for the preparation of advanced modern infrared systems. Device Physics of Narrow Gap Semiconductors offers descriptions of the materials science and device physics of these unique materials. Topics covered include impurities and defects, recombination mechanisms, surface and interface properties, and the properties of low dimensional systems for infrared applications. This book will help readers to understand not only the semiconductor physics and materials science, but also how they relate to advanced opto-electronic devices. The last chapter applies the understanding of device physics to photoconductive detectors, photovoltaic infrared detector...

  12. Manipulating semiconductor colloidal stability through doping. (United States)

    Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N


    The interface between a doped semiconductor material and electrolyte solution is of considerable fundamental interest, and is relevant to systems of practical importance. Both adjacent domains contain mobile charges, which respond to potential variations. This is exploited to design electronic and optoelectronic sensors, and other enabling semiconductor colloidal materials. We show that the charge mobility in both phases leads to a new type of interaction between semiconductor colloids suspended in aqueous electrolyte solutions. This interaction is due to the electrostatic response of the semiconductor interior to disturbances in the external field upon the approach of two particles. The electrostatic repulsion between two charged colloids is reduced from the one governed by the charged groups present at the particles surfaces. This type of interaction is unique to semiconductor particles and may have a substantial effect on the suspension dynamics and stability.

  13. Tiger team assessment of the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)



    This document contains findings identified during the Tiger Team Compliance Assessment of the Department of Energy's (DOE's) Y-12 Plant in Oak Ridge, Tennessee. The Y-12 Plant Tiger Team Compliance Assessment is comprehensive in scope. It covers the Environmental, Safety, and Health (including Occupational Safety and Health Administration (OSHA) compliance), and Management areas and determines the plant's compliance with applicable federal (including DOE), state, and local regulations and requirements. 4 figs., 12 tabs.

  14. Site descriptions of environmental restoration units at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Kuhaida, A.J. Jr.; Parker, A.F.


    This report provides summary information on Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) sites as listed in the Oak Ridge Reservation Federal Facility Agreement (FFA), dated January 1, 1992, Appendix C. The Oak Ridge National Laboratory was built in 1943 as part of the World War II Manhattan Project. The original mission of ORNL was to produce and chemically separate the first gram-quantities of plutonium as part of the national effort to produce the atomic bomb. The current mission of ORNL is to provide applied research and development in support of the U.S. Department of Energy (DOE) programs in nuclear fusion and fission, energy conservation, fossil fuels, and other energy technologies and to perform basic scientific research in selected areas of the physical, life, and environmental sciences. ER is also tasked with clean up or mitigation of environmental impacts resulting from past waste management practices on portions of the approximately 37,000 acres within the Oak Ridge Reservation (ORR). Other installations located within the ORR are the Gaseous Diffusion Plant (K-25) and the Y-12 plant. The remedial action strategy currently integrates state and federal regulations for efficient compliance and approaches for both investigations and remediation efforts on a Waste Area Grouping (WAG) basis. As defined in the ORR FFA Quarterly Report July - September 1995, a WAG is a grouping of potentially contaminated sites based on drainage area and similar waste characteristics. These contaminated sites are further divided into four categories based on existing information concerning whether the data are generated for scoping or remedial investigation (RI) purposes. These areas are as follows: (1) Operable Units (OU); (2) Characterization Areas (CA); (3) Remedial Site Evaluation (RSE) Areas; and (4) Removal Site Evaluation (RmSE) Areas.

  15. Greenland Fracture Zone-East Greenland Ridge(s) revisited: Indications of a C22-change in plate motion?

    DEFF Research Database (Denmark)

    Døssing, Arne; Funck, T.


    Changes in the lithospheric stress field, causing axial rift migration and reorientation of the transform, are generally proposed as an explanation for anomalously old crust and/or major aseismic valleys in oceanic ridge-transform-ridge settings. Similarly, transform migration of the Greenland...

  16. Tectonics of the Ninetyeast Ridge derived from spreading records in adjacent oceanic basins and age constraints of the ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Abraham, H.; Sager, W.W.; Pringle, M.S.; Frey, F.; Rao, D.G.; Levchenko, O.V.

    and magnetic anomaly ages implies that the hot spot first emplaced NER volcanoes on the Indian plate at a distance from the Wharton Ridge, but as the northward drifting spreading ridge approached the hot spot, the two interacted, keeping later NER volcanism...

  17. Harmonic Generation and Wave Mixing in Confinement Structures: An Account of Pump Depletion in Second-Order Nonlinear Multilayer Microcavities

    Directory of Open Access Journals (Sweden)

    Serge Gauvin


    Full Text Available In presence of weakly nonlinear media, it is tempting to neglect pump wave depletion when calculating the intensity of the various generated nonlinear components. However, even in the case of very weak pump wave depletion conditions, an optical structure that allows multipass optical paths, such as high finesse multilayer microcavities, could lead to significant cumulative pump wave depletion. In such conditions, neglecting pump depletion might lead to large computational errors. A matrix formalism devoted to such pump depletion in planar layered nonlinear structures without resort to the “bound” and “free” waves concept is described. A general approach that makes use of “intrinsic” and “extrinsic” waves concept is given, through a slight modification of the canonical propagation matrix. The theoretical results show that even in the case of very weak pump depletion conditions, the cumulative effect due to confinement actually leads to very significant effects. It turns out that taking into account the pump depletion is mandatory for numerous experimental conditions. This matrix formalism applies to absorbing media, and is extensible to include the case of anisotropic layers and cascading effects.

  18. Second-harmonic generation using 4-quasi-phasematching in a GaAs whispering-gallery-mode microcavity. (United States)

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


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

  19. Second-harmonic generation using -quasi-phasematching in a GaAs whispering-gallery-mode microcavity (United States)

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


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

  20. Photonic transistor and router using a single quantum-dot-confined spin in a single-sided optical microcavity. (United States)

    Hu, C Y


    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.