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Sample records for amplified spontaneous emission

  1. Temporal and transverse coherence of self-amplified spontaneous emission

    International Nuclear Information System (INIS)

    The authors review the coherence properties of the self-amplified spontaneous emission (SASE). Temporally, SASE is similar to the spontaneous undulator radiation except that the spectral bandwidth is about ten times narrower compared with typical undulator radiation. The situation is quite different in the transverse dimension, where SASE is fully coherent

  2. Amplified spontaneous emission and its restraint in a terawatt Ti:sapphire amplifier

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped_pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and spectral domain. Pulses as short as 38 fs were amplified to peak power of 1.4 TW. The power ratio between the amplified femtosecond pulse and the ASE was higher than 106:1.

  3. Pulse compression method for amplified spontaneous emission smooth beams

    International Nuclear Information System (INIS)

    In order to increase the intensity on target and the coupling efficiency, based on optical gain switching theory the paper presents a method for shortening the amplified spontaneous emission (ASE) smooth pulses. The experiment has been per- formed on EMG-150, a discharge laser in the Department of Experimental Physics, University of Szeged. As a result, the pulse bandwidth is shortened to 7.5 ns from 14.5 ns. and the uniformity of the ASE beams is not affected. (authors)

  4. Self-amplified spontaneous emission for short wavelength coherent radiation

    International Nuclear Information System (INIS)

    We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

  5. 2-.mu.m fiber amplified spontaneous emission (ASE) source

    Science.gov (United States)

    Jiang, Shibin (Inventor); Wu, Jianfeng (Inventor); Geng, Jihong (Inventor)

    2007-01-01

    A 2-.mu.m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm.sub.2O.sub.3) or 0.1-5 wt% holmium oxides (Ho.sub.2O.sub.3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.

  6. Investigation of the amplified spontaneous emission in Nd: glass disk laser amplifier

    International Nuclear Information System (INIS)

    A model program has been established to investigate the amplified spontaneous emission (ASE) in the Nd: glass disk amplifier with the Monte Carlo method and rays tracing. The distribution of ASE loading on the edge of a disk is firstly calculated. The effect of disk aspect radio on ASE gain reduction is also investigated. Allowance is made for the effect of different reflectivity under the condition of different incidence on two faces

  7. Optical steganography based on amplified spontaneous emission noise.

    Science.gov (United States)

    Wu, Ben; Wang, Zhenxing; Tian, Yue; Fok, Mable P; Shastri, Bhavin J; Kanoff, Daniel R; Prucnal, Paul R

    2013-01-28

    We propose and experimentally demonstrate an optical steganography method in which a data signal is transmitted using amplified spontaneous emission (ASE) noise as a carrier. The ASE serving as a carrier for the private signal has an identical frequency spectrum to the existing noise generated by the Erbium doped fiber amplifiers (EDFAs) in the transmission system. The system also carries a conventional data channel that is not private. The so-called "stealth" or private channel is well-hidden within the noise of the system. Phase modulation is used for both the stealth channel and the public channel. Using homodyne detection, the short coherence length of the ASE ensures that the stealth signal can only be recovered if the receiver closely matches the delay-length difference, which is deliberately changed in a dynamic fashion that is only known to the transmitter and its intended receiver. PMID:23389187

  8. A coupling model for amplified spontaneous emission in laser resonators

    International Nuclear Information System (INIS)

    The competition between amplified spontaneous emission (ASE) and main laser in solid-state laser resonators is investigated both theoretically and experimentally. A coupled model using the spatial volume integral instead of the Monte Carlo type raytrace technique is proposed to depict ASE in the laser resonators. This model is able to evaluate all possible reflections at both the polishing surface and the diffusive side, to calculate ASE for an inhomogeneous gain distribution, and to include the spectral correction. An experiment is carefully designed to verify the theoretical model and to investigate the distinct physical properties caused by the coupling between ASE and the laser oscillations. The experimental data exhibit an excellent agreement with the theoretical predictions. According to that model, we confirm that ASE in thin-disk lasers can be characterized approximately by the product of the threshold gain of the resonator and the diameter of the disks, as laser modes are highly overlapped with the pumping beam. Theoretical evaluation shows that the scattering characteristic of the disk side impacts on ASE significantly. Furthermore, we point out that ASE decreases output laser power by affecting threshold pumping power, while slope efficiency is not changed by ASE. This observation provides us with a simple way to estimate the decrease of the optical efficiency by ASE. (paper)

  9. A coupling model for amplified spontaneous emission in laser resonators

    Science.gov (United States)

    Su, Hua; Wang, Xiaojun; Shang, Jianli; Yu, Yi; Tang, Chun

    2015-10-01

    The competition between amplified spontaneous emission (ASE) and main laser in solid-state laser resonators is investigated both theoretically and experimentally. A coupled model using the spatial volume integral instead of the Monte Carlo type raytrace technique is proposed to depict ASE in the laser resonators. This model is able to evaluate all possible reflections at both the polishing surface and the diffusive side, to calculate ASE for an inhomogeneous gain distribution, and to include the spectral correction. An experiment is carefully designed to verify the theoretical model and to investigate the distinct physical properties caused by the coupling between ASE and the laser oscillations. The experimental data exhibit an excellent agreement with the theoretical predictions. According to that model, we confirm that ASE in thin-disk lasers can be characterized approximately by the product of the threshold gain of the resonator and the diameter of the disks, as laser modes are highly overlapped with the pumping beam. Theoretical evaluation shows that the scattering characteristic of the disk side impacts on ASE significantly. Furthermore, we point out that ASE decreases output laser power by affecting threshold pumping power, while slope efficiency is not changed by ASE. This observation provides us with a simple way to estimate the decrease of the optical efficiency by ASE.

  10. The generation of amplified spontaneous emission in high‐power CPA laser systems

    OpenAIRE

    Keppler, Sebastian; Sävert, Alexander; Körner, Jörg; Hornung, Marco; Liebetrau, Hartmut; Hein, Joachim; Kaluza, Malte Christoph

    2015-01-01

    Abstract An analytical model is presented describing the temporal intensity contrast determined by amplified spontaneous emission in high‐intensity laser systems which are based on the principle of chirped pulse amplification. The model describes both the generation and the amplification of the amplified spontaneous emission for each type of laser amplifier. This model is applied to different solid state laser materials which can support the amplification of pulse durations ≤ 350 fs . The res...

  11. Numerical Modelling of Spontaneous Emission in Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Andersen, Ulrik Lund; Rottwitt, Karsten

    2013-01-01

    . However, it is well accepted that one contribution to the noise performance originates from vacuum fluctuations. In this work we show a novel approach to predict the spontaneous radiation from a parametric amplifier. In the approach the propagating fields are treated as a sum of a classical mean field......Fiber optical parametric processes offer a wide range of applications including phase sensitive as well as phase insensitive amplification, wavelength conversion and signal regeneration. One of the difficult challenges is any of these applications is to predict their associated noise performance...

  12. Broadband amplified spontaneous emission from Er3+-doped single-mode tellurite fibre

    Institute of Scientific and Technical Information of China (English)

    Chen Dong-Dan; Zhang Qin-Yuan; Liu Yue-Hui; Xu Shan-Hui; Yang Zhong-Min; Deng Zai-De; Jiang Zhong-Hong

    2006-01-01

    This paper reports on the fabrication and characterization of a newly erbium-doped single-mode tellurite glass-fibre applicable for 1.5-μm optical amplifiers. A very broad erbium amplified spontaneous emission in the range 1450-1650 nm from erbium-doped single-mode tclluritc glass-fibre is obtained upon excitation of a 980-nm laser diode. The effects of the length of glass-fibre and the pumping power of laser diode on the amplified spontaneous emission are discussed.The result indicates that the tellurite glass-fibre is a promising candidate for designing fibre-optic amplifiers and lasers.

  13. Thermal radiation and amplified spontaneous emission from a random medium

    OpenAIRE

    Beenakker, C. W. J.

    1998-01-01

    We compute the statistics of thermal emission from systems in which the radiation is scattered chaotically, by relating the photocount distribution to the scattering matrix - whose statistical properties are known from random-matrix theory. We find that the super-Poissonian noise is that of a black body with a reduced number of degrees of freedom. The general theory is applied to a disordered slab and to a chaotic cavity, and is extended to include amplifying as well as absorbing systems. We ...

  14. Amplified spontaneous emission pulses for high-power supercontinuum generation

    Directory of Open Access Journals (Sweden)

    Huan Huan Liu

    2016-03-01

    Full Text Available The authors demonstrate an incoherent light source based on a reflective semiconductor optical amplifier as pump for high-power supercontinuum generation for the first time. The obtained power level is about 160 mW and 20 dB spectral bandwidth is around 170 nm.

  15. General theory for spontaneous emission in active dielectric microstructures: Example of a fiber amplifier

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    A model for spontaneous emission in active dielectric microstructures is given in terms of the classical electric field Green's tensor and the quantum-mechanical operators for the generating currents. A formalism is given for calculating the Green's tensor, which does not rely on the existence...... of a complete power orthogonal set of electromagnetic modes, and the formalism may therefore be applied to microstructures with gain and/or absorption. The Green's tensor is calculated for an optical fiber amplifier, and the spontaneous emission in fiber amplifiers is studied with respect to the position......, transition frequency, and vector orientation of a spatially localized current source. Radiation patterns are studied using a Poynting vector approach taking into account amplification or absorption from an active medium in the fiber....

  16. Criterion of transverse coherence of self-amplified spontaneous emission in high gain free electron laser amplifiers

    International Nuclear Information System (INIS)

    In a high gain free electron laser amplifier based on Self-Amplified Spontaneous Emission (SASE) the spontaneous radiation generated by an electron beam near the undulator entrance is amplified many orders of magnitude along the undulator. The transverse coherence properties of the amplified radiation depends on both the amplification process and the coherence of the seed radiation (the undulator radiation generated in the first gain length or so). The evolution of the transverse coherence in the amplification process is studied based on the solution of the coupled Maxwell-Vlasov equations including higher order transverse modes. The coherence of the seed radiation is determined by the number of coherent modes in the phase space area of the undulator radiation. We discuss the criterion of transverse coherence and identify governing parameters over a broad range of parameters. In particular we re-examine the well known emittance criterion for the undulator radiation, which states that full transverse coherence is guaranteed if the rms emittance is smaller than the wavelength divided by 4π. It is found that this criterion is modified for SASE because of the different optimization conditions required for the electron beam. Our analysis is a generalization of the previous study by Yu and Krinsky for the case of vanishing emittance with parallel electron beam. Understanding the transverse coherence of SASE is important for the X-ray free electron laser projects now under consideration at SLAC and DESY

  17. Effect of amplified spontaneous emission and parasitic oscillations on the performance of cryogenically-cooled slab amplifiers

    Czech Academy of Sciences Publication Activity Database

    Sawicka, Magdalena; Divoký, Martin; Lucianetti, Antonio; Mocek, Tomáš

    2013-01-01

    Roč. 31, č. 4 (2013), s. 553-560. ISSN 0263-0346 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143 Grant ostatní: HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : amplified spontaneous emission * cryogenic cooling * parasitic oscillations * slab lasers * Yb: YAG , Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.701, year: 2013

  18. Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive transparent electrode

    Science.gov (United States)

    Reufer, M.; Feldmann, J.; Rudati, P.; Ruhl, A.; Müller, D.; Meerholz, K.; Karnutsch, C.; Gerken, M.; Lemmer, U.

    2005-05-01

    We demonstrate that the amplified spontaneous emission (ASE) threshold in multilayer waveguide structures suitable for the use in future organic injection lasers can be drastically reduced by inserting a crosslinked hole transport layer (HTL) between a highly conductive indium tin oxide (ITO) electrode and the polymer emission layer. While no ASE is observed when the active layer material is directly spincoated onto the ITO electrode, it can be completely restored upon insertion of a 300-nm-thick HTL. This observation is attributed to reduced attenuation of the waveguided mode enabling the ASE process and is theoretically confirmed by calculations of the mode intensity fraction propagating in the absorptive ITO electrode.

  19. Effect of amplified spontaneous emission on selectivity of laser photoionisation of the 177Lu radioisotope

    Science.gov (United States)

    D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Panchenko, V. Ya; Firsov, V. A.; Tsvetkov, G. O.

    2016-06-01

    A significant deselecting effect of amplified spontaneous emission has been observed in the experiments on selective laser photoionisation of the 177Lu radioisotope according to the scheme 5d6s2 2D3/2 → 5d6s6p 4Fo5/2 (18505 cm-1) → 5d6s7s 4D3/2(37194 cm-1) → autoionisation state (53375 cm-1). The effect is conditioned by involvement of non-target isotopes from the lower metastable level 5d6s2 2D5/2(1994 cm-1) into the ionisation process. Spectral filtering of spontaneous emission has allowed us to significantly increase the selectivity of the photoionisation process of the radioisotope and to attain a selectivity value of 105 when using saturating light intensities.

  20. Brillouin optical correlation domain analysis with 4 millimeter resolution based on amplified spontaneous emission.

    Science.gov (United States)

    Cohen, Raphael; London, Yosef; Antman, Yair; Zadok, Avi

    2014-05-19

    A new technique for Brillouin scattering-based, distributed fiber-optic measurements of temperature and strain is proposed, analyzed, simulated, and demonstrated. Broadband Brillouin pump and signal waves are drawn from the filtered amplified spontaneous emission of an erbium-doped fiber amplifier, providing high spatial resolution. The reconstruction of the position-dependent Brillouin gain spectra along 5 cm of a silica single-mode fiber under test, with a spatial resolution of 4 mm, is experimentally demonstrated using a 25 GHz-wide amplified spontaneous emission source. A 4 mm-long localized hot spot is identified by the measurements. The uncertainty in the reconstruction of the local Brillouin frequency shift is ± 1.5 MHz. The single correlation peak between the pump and signal is scanned along a fiber under test using a mechanical variable delay line. The analysis of the expected spatial resolution and the measurement signal-to-noise ratio is provided. The measurement principle is supported by numerical simulations of the stimulated acoustic field as a function of position and time. Unlike most other Brillouin optical correlation domain analysis configurations, the proposed scheme is not restricted by the bandwidth of available electro-optic modulators, microwave synthesizers, or pattern generators. Resolution is scalable to less than one millimeter in highly nonlinear media. PMID:24921326

  1. Amplified spontaneous emission from the exciplex state of a conjugated polymer "PFO" in oleic acid

    Science.gov (United States)

    Idriss, Hajo; Taha, Kamal K.; Aldaghri, O.; Alhathlool, R.; AlSalhi, M. S.; Ibnaouf, K. H.

    2016-09-01

    The amplified spontaneous emission (ASE) characteristics of a conjugated polymer poly (9, 9-dioctylfluorenyl-2, 7-diyl) (PFO) in oleic acid have been studied under different concentrations and temperatures. Here, the ASE spectra of PFO in oleic acid have been obtained using a transverse cavity configuration where the conjugated PFO was pumped by laser pulses from the third harmonic of Nd: YAG laser (355 nm). The PFO in oleic acid produces ASE from an exciplex state - a new molecular species. The obtained results were compared with the PFO in benzene. Such ASE spectra from the exciplex state have not been observed for the PFO in benzene.

  2. Linac-based, intense, coherent x-ray source using self-amplified spontaneous emission

    International Nuclear Information System (INIS)

    In this article, the author discusses the principles of self-amplified spontaneous emission (SASE), how the SASE could be the basis of next generation light sources exceeding the current performance -- by many orders of magnitude in spectral brightness, and by a factor of a hundred in time resolution. He also discusses how the SLAC linac, due to its high energy and its precision control, is ideally suited for the x-ray SASE. Therefore, using the SLAC linac for generation of x-ray SASE for the frontier of the photon sciences will ensure that the SLAC linac remain scientifically vigorous for a long time

  3. Solid state solvation effect and reduced amplified spontaneous emission threshold value of glass forming DCM derivative in PMMA films

    International Nuclear Information System (INIS)

    Molecule crystallization is one of the limitations for obtaining high-gain organic laser systems. One of the examples is well known red laser dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The lowest threshold value of amplified spontaneous emission was achieved by doping 2 wt% of DCM molecule in tris-(8-hydroxy quinoline) aluminum (Alq3) matrix. Further increase of the DCM dye concentration makes the system less efficient as its threshold value increases. It is due to large intermolecular interaction, which induces photoluminescence quenching. Compounds with reduced intermolecular interaction could be prospective in organic laser systems due to higher possible doping. In this work photoluminescence and amplified spontaneous emission properties of modified DCM molecule in poly(methyl methacrylate) (PMMA) matrix were investigated. Bulky trityloxyethyl groups were attached to the donor part of DCM. These groups increase intermolecular distance wherewith reduce photoluminescence quenching. More than one order of magnitude lower excitation threshold energy of the amplified spontaneous emission was achieved in doped polymer films with investigated compound in comparison to doped polymer with DCM. It means that the investigated compound is more perspective as a laser material compared to the previously studied. In addition, amplified spontaneous emission maximum could be tuned within 15 nm by changing concentration from 0.1 wt% to 10 wt% DWK-1 in PMMA matrix due to solid state solvation effect. - Highlights: • Bulky groups attached to DCM dye reduce photoluminescence quenching. • Amplified spontaneous emission is in red spectral region. • Amplified spontaneous emission spectra were tuned by 15 nm. • Amplified spontaneous emission threshold value was reduced by one order of magnitude

  4. Obtaining attosecond X-ray pulses using a self-amplified spontaneous emission free electron laser

    International Nuclear Information System (INIS)

    We describe a technique for the generation of a solitary attosecond X-ray pulse in a free electron laser (FEL), via a process of self-amplified spontaneous emission. In this method, electrons experience an energy modulation upon interacting with laser pulses having a duration of a few cycles within single-period wiggler magnets. Two consecutive modulation sections, followed by compression in a dispersive section, are used to obtain a single, sub-femtosecond spike in the electron peak current. This region of the electron beam experiences an enhanced growth rate for FEL amplification. After propagation through a long undulator,this current spike emits a ∼250 attosecond X-ray pulse whose intensity dominates the X-ray emission from the rest of the electron bunch

  5. Fluorescence and amplified spontaneous emission of glass forming compounds containing styryl-4H-pyran-4-ylidene fragment

    Energy Technology Data Exchange (ETDEWEB)

    Vembris, Aivars, E-mail: aivars.vembris@cfi.lu.lv [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga LV-1063 (Latvia); Muzikante, Inta [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga LV-1063 (Latvia); Karpicz, Renata; Sliauzys, Gytis [Institute of Physics, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius (Lithuania); Miasojedovas, Arunas; Jursenas, Saulius [Institute of Applied Research, Vilnius University, Sauletekio 9-III, LT-10222 Vilnius (Lithuania); Gulbinas, Vidmantas [Institute of Physics, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius (Lithuania)

    2012-09-15

    Potential of glassy films of newly synthesised low molecular weight organic molecules for light amplification and lasing applications has been investigated by analysing fluorescence, transient differential absorption and amplified spontaneous emission properties. These non-symmetric and symmetric molecules contain styryl-4H-pyran-4-ylidene fragment with three different electron acceptor groups: dicyanomethylene, barbituric acid, indene-1,3-dione. Fluorescence quantum yields of the investigated compounds in solutions are between 0.32 and 0.54, while they drop down by an order of magnitude in thin solid films. Incorporation of bulky side groups reduced excitonic interactions enabling manifestation of amplified spontaneous emission in the neat films of the investigated derivatives. - Highlights: Black-Right-Pointing-Pointer Bulky substituents attached to DCM dye enable formation of neat glassy films. Black-Right-Pointing-Pointer Investigated dyes show amplified spontaneous emission in neat films. Black-Right-Pointing-Pointer Two electron donor groups negatively influence light amplification.

  6. Fluorescence and amplified spontaneous emission of glass forming compounds containing styryl-4H-pyran-4-ylidene fragment

    International Nuclear Information System (INIS)

    Potential of glassy films of newly synthesised low molecular weight organic molecules for light amplification and lasing applications has been investigated by analysing fluorescence, transient differential absorption and amplified spontaneous emission properties. These non-symmetric and symmetric molecules contain styryl-4H-pyran-4-ylidene fragment with three different electron acceptor groups: dicyanomethylene, barbituric acid, indene-1,3-dione. Fluorescence quantum yields of the investigated compounds in solutions are between 0.32 and 0.54, while they drop down by an order of magnitude in thin solid films. Incorporation of bulky side groups reduced excitonic interactions enabling manifestation of amplified spontaneous emission in the neat films of the investigated derivatives. - Highlights: ► Bulky substituents attached to DCM dye enable formation of neat glassy films. ► Investigated dyes show amplified spontaneous emission in neat films. ► Two electron donor groups negatively influence light amplification.

  7. Enhanced amplified spontaneous emission in a quantum dot-doped polymer-dispersed liquid crystal

    Science.gov (United States)

    Cao, Mingxuan; Zhang, Yating; Song, Xiaoxian; Che, Yongli; Zhang, Haiting; Yan, Chao; Dai, Haitao; Liu, Guang; Zhang, Guizhong; Yao, Jianquan

    2016-07-01

    Quantum dot-doped polymer-dispersed liquid crystals (QD-PDLCs) were prepared by photoinitiated polymerization and sealed in capillary tubes. The concentration of QDs in the PDLC was 1 wt%. Amplified spontaneous emission (ASE) of the quantum dot-doped polymer-dispersed liquid crystals was observed with 532 nm wavelength laser excitation. The threshold for ASE was 6 mJ cm‑2, which is much lower than that for homogeneous quantum dot-doped polymer (25 mJ cm‑2). The threshold for ASE was dramatically enhanced when the working temperature exceeded the clearing point of the liquid crystal; this result demonstrates that multi-scattering caused by the liquid crystals effectively improved the path length or dwell time of light in the gain region, which played a key role in decreasing the threshold for ASE.

  8. Nematicon-driven injection of amplified spontaneous emission into an optical fiber.

    Science.gov (United States)

    Bolis, Serena; Virgili, Tersilla; Rajendran, Sai Kiran; Beeckman, Jeroen; Kockaert, Pascal

    2016-05-15

    We investigate experimentally the interaction between amplified spontaneous emission (ASE) and a soliton, which are both generated in a dye-doped nematic liquid crystal (LC) cell. A light beam is injected through an optical fiber slid into the cell to form a soliton beam. ASE is then automatically collected by this self-induced waveguide and efficiently coupled into the same optical fiber, in the backward direction. We demonstrate that the presence of the soliton improves the ASE collection by one order of magnitude. We also show that the ASE is highly polarized in the plane of the LC cell and that the ASE spectrum depends on the pump stripe orientation with respect to the LC director. The origin of the spectral anisotropy of the gain curves is determined with the help of femtosecond pump-probe spectroscopy. PMID:27176973

  9. Effect of different metal-backed waveguides on amplified spontaneous emission

    Institute of Scientific and Technical Information of China (English)

    Zhang Bo; Hou Yan-Bing; Lou Zhi-Dong; Teng Feng; Liu Xiao-Jun; Hu Bing; Meng Ling-Chuan; Wu Wen-Bin

    2012-01-01

    We investigate the effect of a metallic electrode on the ability for poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene](MEH-PPV) film to undergo amplified spontaneous emission (ASE).The threshold of the device with Ag cladding is about 10 times greater than that of a metal-free device,but metal such as A1 completely shuts off ASE.The ASE recurs when a thin spacer layer,such as a few nanometers of SiO2,is introduced between the MEH-PPV film and the Al cladding.Compared with the Cu or Al electrode,the Ag cladding is most suited to serve as an electrode with its low optical loss due to its high work-function and reflectivity.

  10. Temporal phase mask encrypted optical steganography carried by amplified spontaneous emission noise.

    Science.gov (United States)

    Wu, Ben; Wang, Zhenxing; Shastri, Bhavin J; Chang, Matthew P; Frost, Nicholas A; Prucnal, Paul R

    2014-01-13

    A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase. PMID:24515055

  11. Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

    CERN Document Server

    Arnold, N D; Banks, G; Bechtold, R; Beczek, K; Benson, C; Berg, S; Berg, W; Biedron, S G; Biggs, J A; Boerste, K; Borland, M; Bosek, M; Brzowski, W R; Budz, J; Carwardine, J A; Castro, P; Chae, Y C; Christensen, S; Clark, C; Conde, M; Crosbie, E A; Decker, G A; Dejus, Roger J; Deleon, H; Den Hartog, P K; Deriy, B N; Dohan, D; Dombrowski, P; Donkers, D; Doose, C L; Dortwegt, R J; Edwards, G A; Eidelman, Y; Erdmann, M J; Error, J J; Ferry, R; Flood, R; Forrestal, J; Freund, H; Friedsam, H; Gagliano, J; Gai, W; Galayda, J N; Gerig, R; Gilmore, R L; Gluskin, E; Goeppner, G A; Goetzen, J; Gold, C; Grelick, A E; Hahne, M W; Hanuska, S; Harkay, K C; Harris, G; Hillman, A L; Hogrefe, R; Hoyt, J; Huang, Z; Jagger, J M; Jansma, W G; Jaski, M; Jones, S J; Keane, R T; Kelly, A L; Keyser, C; Kim, K J; Kim, S H; Kirshenbaum, M; Klick, J H; Knoerzer, K; Knott, M; Koldenhoven, R J; Labuda, S; Laird, R; Lang, J; Lenkszus, F R; Lessner, E S; Lewellen, J W; Li, Y; Lill, R M; Lumpkin, Alex H; Makarov, O A; Markovich, G M; McDowell, M; McDowell, W P; McNamara, P E; Meier, T; Meyer, D; Michalek, W; Milton, S V; Moe, H; Moog, E; Morrison, L; Nassiri, A; Noonan, J R; Otto, R; Pace, J; Pasky, S J; Penicka, J M; Pietryla, A F; Pile, G; Pitts, C; Power, J; Powers, T; Putnam, C C; Puttkammer, A J; Reigle, D; Reigle, L; Ronzhin, D; Rotela, E R; Russell, E F; Sajaev, Vadim; Sarkar, S; Scapino, J C; Schröder, K; Seglem, R A; Sereno, N S; Sharma, S K; Sidarous, J F; Singh, O; Smith, T L; Soliday, R; Sprau, G A; Stein, S J; Stejskal, B; Svirtun, V; Teng, L C; Theres, E; Thompson, K; Tieman, B J; Torres, J A; Trakhtenberg, E; Travish, G; Trento, G F; Vacca, J; Vasserman, I B; Vinokurov, N A; Walters, D R; Wang, J; Wang, X J; Warren, J; Wesling, S; Weyer, D L; Wiemerslage, G; Wilhelmi, K; Wright, R; Wyncott, D; Xu, S; Yang, B X; Yoder, W; Zabel, R B

    2001-01-01

    Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

  12. Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

    Science.gov (United States)

    AL-Aqmar, Dalal M.; Abdelkader, H. I.; Abou Kana, Maram T. H.

    2015-09-01

    The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl4) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl4 and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF4 that was decreased to ∼56% of the initial ASE after continuously pumping with 400 mW for 132 min.

  13. Amplified spontaneous emission from a microtube cavity with whispering gallery modes

    Science.gov (United States)

    Rakovich, Y. P.; Balakrishnan, S.; Gun'ko, Y.; Perova, T. S.; Moore, A.; Donegan, J. F.

    2007-05-01

    We present a detailed study of the photonic modes in microtube cavity of ~ 7-8 μm outer diameter that can act as micron-scale optical cylindrical resonator. We demonstrate a new route to the fabrication of individual microtubes with the maximum length of 200 μm, using a vacuum assisted wetting and filtration through a microchannel glass matrix. The microtubes were studied using micro-photoluminescence spectroscopy and luminescence lifetime imaging confocal microscopy. In the emission spectra of the microresonators we find periodic very narrow peaks corresponding to the whispering gallery modes of two orthogonal polarizations with quality factors upto 3200 at room temperature. In order to identify the peaks in the observed mode structure, we have adopted the boundary-value solution to the problem of scattering of electromagnetic waves by a dielectric micro-cylinder. A strong enhancement in photoluminescence decay rates at high excitation power suggest the occurrence of amplified spontaneous emission from a single microtube. The evanescent field in these photonic structures extends a couple of micrometers into the surroundings providing the possibility for efficient coupling to an external photonic device.

  14. Amplified spontaneous emission from DCJTB encapsulated in mesostructured composite silica SBA-15.

    Science.gov (United States)

    Zhang, Dingke; Duan, Zhuojun; Wang, Yu; Zhang, Peng; Chen, Shijian

    2016-06-10

    Amplified spontaneous emission (ASE) characteristics of a red dye 4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7- etramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) encapsulated in a highly ordered mesoporous SBA-15 were studied. The mesoporous composite silica film loaded with organic dye has been successfully synthesized by a solgel reaction process and a simple postgrafting method at room temperature. The spectrum narrowing phenomena has been observed when the composite film is pumped at λp=532  nm by a Nd:YAG ed laser. There is a substantial reduction in the full width at half-maximum of the emitting light, which is one of the signatures of the presence of ASE. The ASE threshold and net gain, respectively, reached 0.03  mJ pulse-1 and 34.7  cm-1 for the DCJTB encapsulated in mesoporous SBA-15 film. The optimized ASE properties owe much to the effects of the better spatial confinement of the molecules in the ordered mesoporous structure of the host SBA-15. PMID:27409033

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

    Science.gov (United States)

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

    2016-02-01

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

  16. First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

    CERN Document Server

    Andruszków, J; Ayvazyan, V T; Baboi, N I; Bakker, R; Balakin, V; Barni, D; Bazhan, A; Bernard, M; Bosotti, A; Bourdon, J C; Brefeld, W; Brinkmann, R; Bühler, S; Carneiro, J P; Castellano, M G; Castro, P; Catani, L; Chel, S; Cho, Y; Choroba, S; Colby, E R; Decking, W; Den Hartog, P; Desmons, M; Dohlus, M; Edwards, D; Edwards, H T; Faatz, B; Feldhaus, J; Ferrario, M; Fitch, M J; Flöttmann, K; Fouaidy, M; Gamp, A; Garvey, Terence; Geitz, M A; Gluskin, E S; Gretchko, V; Hahn, U; Hartung, W H; Hubert, D; Hüning, M; Ischebek, R; Jablonka, M; Joly, J M; Juillard, M; Junquera, T; Jurkiewicz, P; Kabel, A C; Kahl, J; Kaiser, H; Kamps, T; Katelev, V V; Kirchgessner, J L; Körfer, M; Kravchuk, L V; Kreps, G; Krzywinski, J; Lokajczyk, T; Lange, R; Leblond, B; Leenen, M; Lesrel, J; Liepe, M; Liero, A; Limberg, T; Lorenz, R; Lu, H H; Lu, F H; Magne, C; Maslov, M A; Materlik, G; Matheisen, A; Menzel, J; Michelato, P; Möller, W D; Mosnier, A; Müller, U C; Napoly, O; Novokhatskii, A V; Omeich, M; Padamsee, H; Pagani, C; Peters, F; Petersen, B; Pierini, P; Pflüger, J; Piot, P; Phung Ngoc, B; Plucinski, L; Proch, D; Rehlich, K; Reiche, S; Reschke, D; Reyzl, I; Rosenzweig, J; Rossbach, J; Roth, S; Saldin, E L; Sandner, W; Sanok, Z; Schlarb, H; Schmidt, G; Schmüser, P; Schneider, J R; Schneidmiller, E A; Schreiber, H J; Schreiber, S; Schütt, P; Sekutowicz, J; Serafini, L; Sertore, D; Setzer, S; Simrock, S; Sonntag, B F; Sparr, B; Stephan, F; Sytchev, V V; Tazzari, S; Tazzioli, F; Tigner, Maury; Timm, M; Tonutti, M; Trakhtenberg, E; Treusch, R; Trines, D; Verzilov, V A; Vielitz, T; Vogel, V; Von Walter, G; Wanzenberg, R; Weiland, T; Weise, H; Weisend, J G; Wendt, M; Werner, M; White, M M; Will, I; Wolff, S; Yurkov, M V; Zapfe, K; Zhogolev, P; Zhou, F

    2000-01-01

    We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.

  17. Conceptual designs of a 50 nm FEL [free-electron laser] oscillator and a 20-40 nm SASE [self-amplified spontaneous emission] amplifier

    International Nuclear Information System (INIS)

    This paper consists of two parts: the conceptual design and optical performance characteristics of a grazing angle-of-incidence ring resonator utilizing multifaceted metal mirrors for use with a 50 nm rf-linac-driven XUV FEL oscillator; and electron beam and wiggler requirements for a self-amplified spontaneous emission (SASE) amplifier to produce high power in the 20 to 40 nm wavelength range. The basis for these studies is the 3-d FEL simulation code FELEX which is used to derive tolerances on mirror figure and thermal distortion, alignment sensitivity, and alternative output coupling methods. The sensitivity of the output characteristics of an XUV FEL SASE amplifier to wiggler field errors is also studied. 17 refs., 8 figs., 2 tabs

  18. Amplified spontaneous emission lifetime based on the different phase matching modes in BaAlBO3F2 crystal

    International Nuclear Information System (INIS)

    Amplified spontaneous emission lifetime (ASEL) distribution characteristics of the new BaAlBO3F2 (BABF) crystal have been calculated via the equations of emitted light intensity and amplified signal intensity gain. The ASEL distribution was calculated and discussed for three types of injection into the BABF crystal based on an optical parametric amplifier. We found ASEL was first distributed mainly in an ellipsoid and then in a torus with the increase of the pump phase matching angle when a monochromatic signal is injected. For the polychromatic signal pulse injection, ASEL is changed from a scattered distribution to a concentrated distribution. For the broadband pump, the ASEL distribution range is greatly expanded because of the increasing phase matching range

  19. Amplified spontaneous emission in active channel waveguides produced by electron-beam lithography in LiF crystals

    International Nuclear Information System (INIS)

    In this letter we report the observation of amplified spontaneous emission of the red light from LiF:F2 centers in active channel waveguides realized by electron-beam lithography in lithium fluoride crystals. Low pumping power densities have been used in quasi-continuous-wave regime at room temperature; the appreciable values of the gain coefficients, 4.67 cm-1 with an exciting power density of 0.31 W/cm2 at 458 nm, make this material a good candidate for the realization of active integrated optical devices. [copyright] 2001 American Institute of Physics

  20. Amplified spontaneous emission of a molecular nitrogen laser excited by an intense relativistic electron beam

    International Nuclear Information System (INIS)

    Report of a study of the shape and length of the output pulse of a molecular nitrogen laser, excited by an intense relativistic electron beam, is described. The rate equations are computer solved, at first ignoring the spontaneous emission during the excitation process. Afterwards the rate equations are solved taking into account excitation functions of various shapes and lengths, related to electron-beam pulses of a few kA and a few nsec. Laser power output, energy, and peak-time, i.e., the time at which the gain reaches its saturated value, are given and discussed as functions of the intensity and rise time of the excitation functions

  1. Superradiance driven by coherent spontaneous emission in a Cherenkov free-electron maser amplifier

    CERN Document Server

    Jaroszynski, D A; McNeil, B W J; Robb, G R M; Aitken, P; Phelps, A D R; Cross, A W; Ronald, K; Shpak, V G; Yalandin, M I; Ginzburg, N S

    2000-01-01

    Superradiance (SR) initiated by coherent spontaneous emission (CSE) has been studied in a 35 GHz high gain free-electron Cherenkov maser. We present experimental results that show the development of ultra-short pulses of radiation in the non-linear superradiant regime which are characterised by a quadratic dependence of the intensity on the current. The self-similar pulses that develop have a duration that scales inversely with the fourth root of the intensity leading to three cycle long pulses at the highest intensity (few MW). The non-linear SR regime is preceded by a stage of linear exponential growth of the microwave pulses with a gain length of 1 cm. The superradiant pulse is shown to evolve from a CSE seed by extrapolating the growth curve. Further confirmation of CSE has been obtained by varying the current pulse shape. By varying the slope of the leading edge, and thus the Fourier components of the longitudinal spectral density, we are able to vary the strength of the CSE source. We compare the experi...

  2. Start-to-end simulation of self-amplified spontaneous emission free electron lasers from the gun through the undulator

    International Nuclear Information System (INIS)

    It is widely appreciated that the performance of self-amplified spontaneous emission free-electron lasers (FELs) depends critically on the properties of the drive beam. In view of this, a multi-laboratory collaboration has explored methods and software tools for integrated simulation of the photoinjector, linear accelerator, bunch compressor, and FEL. Rather than create a single code to handle such a system, our goal has been a robust, generic solution wherein pre-existing simulation codes are used sequentially. We have standardized on the use of Argonne National Laboratory's Self-Describing Data Sets file protocol for transfer of data among codes. The simulation codes used are PARMELA, elegant, and GENESIS. We describe the software methodology and its advantages, then provide examples involving Argonne's Low-Energy Undulator Test Line and Stanford Linear Accelerator Center's Linac Coherent Light Source. We also indicate possible future direction of this work

  3. A linear integral-equation-based computer code for self-amplified spontaneous emission calculations of free-electron lasers

    International Nuclear Information System (INIS)

    The linear integral-equation-based computer code 'Roger Oleg Nikolai' (RON), which was recently developed at Argonne National Laboratory, was used to calculate the self-amplified spontaneous emission (SASE) performance of the free-electron laser (FEL) being built at Argonne. Signal growth calculations under different conditions were used to estimate tolerances of actual design parameters and to estimate optimal length of the break sections between undulator segments. Explicit calculation of the radiation field was added recently. The measured magnetic fields of five undulators were used to calculate the gain for the Argonne FEL. The result indicates that the real undulators for the Argonne FEL (the effect of magnetic field errors alone) will not significantly degrade the FEL performance. The capability to calculate the small-signal gain for an FEL-oscillator is also demonstrated

  4. Analysis of Statistical Correlations and Intensity Spiking in the Self-Amplified Spontaneous-Emission Free-Electron Laser

    International Nuclear Information System (INIS)

    The narrow band chaotic output of the self-amplified spontaneous-emission free-electron laser (SASE FEL) exhibits intensity spikes. In the linear regime before saturation, we use an approach developed by Rice to determine probability distributions for the peak values of intensity in both the time and frequency domains. We also find the average number of spikes per unit time or frequency. In addition, we derive joint probabilities for the intensity in the output pulse to have values I1 and I2 at times t1 and t2, and for the spectral intensity to have values (tilde I)1 and (tilde I)2 at frequencies ω1 and ω2

  5. Start-to-end simulation of self-amplified spontaneous emission free electron lasers from the gun through the undulator

    CERN Document Server

    Borland, M M; Emma, P; Lewellen, J W; Bharadwaj, V K; Fawley, W M; Krejcik, P; Limborg, C; Milton, S V; Nuhn, H D; Soliday, R; Woodley, M

    2002-01-01

    It is widely appreciated that the performance of self-amplified spontaneous emission free-electron lasers (FELs) depends critically on the properties of the drive beam. In view of this, a multi-laboratory collaboration has explored methods and software tools for integrated simulation of the photoinjector, linear accelerator, bunch compressor, and FEL. Rather than create a single code to handle such a system, our goal has been a robust, generic solution wherein pre-existing simulation codes are used sequentially. We have standardized on the use of Argonne National Laboratory's Self-Describing Data Sets file protocol for transfer of data among codes. The simulation codes used are PARMELA, elegant, and GENESIS. We describe the software methodology and its advantages, then provide examples involving Argonne's Low-Energy Undulator Test Line and Stanford Linear Accelerator Center's Linac Coherent Light Source. We also indicate possible future direction of this work.

  6. A Selective C and L-Band Amplified Spontaneous Emission Source Using a 1 × 2 Optical Switch

    Institute of Scientific and Technical Information of China (English)

    HUANG Wen-Cai; MING Hai; CAI Zhi-Ping; XU Hui-Ying; YE Chen-Chun

    2005-01-01

    @@ We report on a band selective amplified spontaneous emission (ASE) source of an erbium-doped fibre (EDF),which can operate in either the C- or L-band region.The band selective ASE source is realized using a pump conversion technique by a 1 × 2 optical switch, which makes the ASE source design convert between a backward and a forward pumped configuration alternately.A heavily doped erbium fibre and a 1480nm laser ()ode are adopted for this design synchronously to enhance the power of L-band ASE.A power of 16.2mW for C-band ASE and 11.8mW for L-band ASE are obtained with a total pump power of 100 mW.

  7. A key issue for next generation diode pumped solid state laser drivers for IFE: amplified spontaneous emission in large size, high gain Yb:YAG slabs

    Energy Technology Data Exchange (ETDEWEB)

    Albach, D; Assemat, F; Bahbah, S; Bourdet, G; Chanteloup, J-C; Piatti, P; Pluvinage, M; Vincent, B; Touze, G L [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Route de Saclay, 91128, Palaiseau (France)], E-mail: daniel.albach@polytechnique.edu

    2008-05-15

    Amplified Spontaneous Emission (ASE) is one of the key issues to be addressed when designing a diode pumped laser with a large transverse size / high gain amplifier. A 3D model using the Monte-Carlo method computing the effect of ASE in the quasi-three-level system of Yb{sup 3+}:YAG is actually under development for the Lucia-project. This work is performed within the Lucia project.

  8. A key issue for next generation diode pumped solid state laser drivers for IFE: amplified spontaneous emission in large size, high gain Yb:YAG slabs

    International Nuclear Information System (INIS)

    Amplified Spontaneous Emission (ASE) is one of the key issues to be addressed when designing a diode pumped laser with a large transverse size / high gain amplifier. A 3D model using the Monte-Carlo method computing the effect of ASE in the quasi-three-level system of Yb3+:YAG is actually under development for the Lucia-project. This work is performed within the Lucia project

  9. The Recombination Mechanism and True Green Amplified Spontaneous Emission in CH3NH3PbBr3 Perovskite

    KAUST Repository

    Priante, Davide

    2015-08-01

    True-green wavelength emitters at 555 nm are currently dominated by III-V semiconductor-based inorganic materials. Nevertheless, due to high lattice- and thermal-mismatch, the overall power efficiency in this range tends to decline for high current density showing the so-called efficiency droop in the green region (“green gap”). In order to fill the research green gap, this thesis examines the low cost solution-processability of organometal halide perovskites, which presents a unique opportunity for light-emitting devices in the green-yellow region owing to their superior photophysic properties such as high photoluminescence quantum efficiency, small capture cross section of defect states as well as optical bandgap tunability across the visible light regime. Specifically, the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material were investigated using low-temperature, power-dependent (77 K), temperature-dependent photoluminescence (PL) measurements. We noted three recombination peaks at 77K, one of which originated from bulk defect states, and other two from surface defect states. The latter were identified as bound-excitonic (BE) radiative transitions related to particle size inhomogeneity or grain size induced surface state in the sample. Both transitions led to PL spectra broadening as a result of concurrent blue- and red-shifts of these excitonic peaks. The blue-shift is most likely due to the Burstein-Moss (band filling) effect. Interestingly, the red-shift of the second excitonic peak becomes pronounced with increasing temperature leading to a true-green wavelength of 553 nm for CH3NH3PbBr3. On the other hand, red-shifted peak originates from the strong absorption in the second excitonic peak owed to the high density of surface states and carrier filling of these states due to the excitation from the first excitonic recombination. We also achieved amplified spontaneous emission around excitation threshold energy of 350 μJ/cm2

  10. Reduced amplified spontaneous emission threshold in organic semiconductor laser structure with relaxed roll-off characteristics under high current densities

    International Nuclear Information System (INIS)

    We reduced the amplified spontaneous emission (ASE) threshold in an organic semiconductor laser structure by the introduction of an exciton blocking layer adjacent to the cathode layer. A phenyl-dipyrenylphosphine oxide (POPy2) layer with the function of an electron transport layer and the exciton blocking layer were inserted between an active layer of 4,4-bis[N-(carbazole)styrylbiphenyl] (BSB-Cz) and a metal cathode layer. The electron injection barrier from POPy2 to BSB-Cz is downward, indicating no net energy barrier, and the hole injection barrier from the BSB-Cz layer into the POPy2 layer is also small because of the similarity between the highest occupied molecular orbital levels of the materials. Therefore, the proposed device structure can avoid extra carrier accumulations at the heterointerface, leading to compatibility in terms of both relaxation of the exciton-polaron annihilation and blocking of the energy transfer from the BSB-Cz layer into the cathode layer. -- Highlights: • An exciton blocking layer (EBL) was introduced between an emitting layer (EML) and a cathode. • The carrier injection barriers between EBL and EML was significantly small. • The ASE threshold was reduced by the exciton confinement in EML. • The electrically pumped device showed relaxation of the roll-off by avoiding carrier accumulation

  11. Amplified and directional spontaneous emission from arbitrary composite bodies: A self-consistent treatment of Purcell effect below threshold

    Science.gov (United States)

    Jin, Weiliang; Khandekar, Chinmay; Pick, Adi; Polimeridis, Athanasios G.; Rodriguez, Alejandro W.

    2016-03-01

    We study amplified spontaneous emission (ASE) from wavelength-scale composite bodies—complicated arrangements of active and passive media—demonstrating highly directional and tunable radiation patterns, depending strongly on pump conditions, materials, and object shapes. For instance, we show that under large enough gain, PT symmetric dielectric spheres radiate mostly along either active or passive regions, depending on the gain distribution. Our predictions are based on a recently proposed fluctuating-volume-current formulation of electromagnetic radiation that can handle inhomogeneities in the dielectric and fluctuation statistics of active media, e.g., arising from the presence of nonuniform pump or material properties, which we exploit to demonstrate an approach to modeling ASE in regimes where Purcell effect (PE) has a significant impact on the gain, leading to spatial dispersion and/or changes in power requirements. The nonlinear feedback of PE on the active medium, captured by the Maxwell-Bloch equations but often ignored in linear formulations of ASE, is introduced into our linear framework by a self-consistent renormalization of the (dressed) gain parameters, requiring the solution of a large system of nonlinear equations involving many linear scattering calculations.

  12. Amplified spontaneous emission in polymer-CdSe/ZnS-nanocrystal DFB structures produced by the holographic method

    Energy Technology Data Exchange (ETDEWEB)

    Smirnova, T N; Yezhov, P V; Kokhtych, L M [Institute of Physics, National Academy of Science, prospect Nauki 46, 03028 Kiev (Ukraine); Sakhno, O V; Stumpe, J [Fraunhofer Institute for Applied Polymer Research, Science Campus Golm, Geiselbergstrasse 69, D-14476 Potsdam (Germany); Goldenberg, L M [Institute for Thin Film Technology and Microsensorics, Kantstrasse 55, D-14513 Teltow (Germany)], E-mail: smirnova@iop.kiev.ua, E-mail: Oksana.Sakhno@iap.fraunhofer.de

    2009-06-17

    Amplified spontaneous emission (ASE) is demonstrated in volume-distributed feedback (DFB) structures, formed by colloidal CdSe/ZnS nanocrystals and ZrO{sub 2} nanoparticles (NPs) in a polymer matrix. Periodic redistribution of the NPs in an organic matrix was carried out by holographic photopolymerization in a specially developed light-sensitive nanocomposite. The composite consists of two acrylate monomers and two types of inorganic NPs. The NPs provide for the formation of two co-phased gratings-a refractive index grating and an optical gain (losses) grating. The core-shell CdSe/ZnS nanocrystals are used as a gain medium, while ZrO{sub 2} NPs create the refractive index grating and enhance the distributed feedback. The period of the volume structure provides the feedback for lasing at the wavelength {lambda}{sub las} of about 575 nm in the second diffraction order. In contrast to known laser systems based on volume DFB cavities, in which the different components of the formulation provide optical gain and feedback, in our case the inorganic NPs serve as an emitting material and can provide simultaneously for feedback. By pumping of DFB structures by a titanium-sapphire laser ({lambda}{sub pump} = 400 nm, pulse duration of 120 fs) normal to the sample plane, the appearance of a sharp stimulated emission along the grating-vector direction is observed. Output intensity of ASE as a function of the pump energy shows a threshold behavior and full width at half-maximum (FWHM) of the ASE spectral band decreases from 33 to 12 nm.

  13. Amplified spontaneous emission from PicoGreen dye intercalated in deoxyribonucleic acid lipid complex

    Science.gov (United States)

    Pradeep, C.; Vallabhan, C. P. G.; Radhakrishnan, P.; Nampoori, V. P. N.

    2015-12-01

    DNA as a genetic biomolecule is more commonly referred to in life sciences, genetics, and microbiology. With the development of ‘DNA photonics’, it has shown tremendous applicability as an optical and photonic material. In this letter, we introduce a novel dye PicoGreen as a lasing medium in which DNA not only acts as a host matrix but also functions as a fluorescence enhancer. A dramatic increase in the fluorescence led us to the observation of optical amplification in dye doped DNA thin films. We also indicate the possible tunability of the output emission in the green-yellow region. With the obtained results, we have enough reasons to lead to the development of DNA-based bio-lasers.

  14. Naphthyl-functionalized oligophenyls: Photophysical properties, film morphology, and amplified spontaneous emission

    Science.gov (United States)

    Ma, Lin; Wu, Zhaoxin; Lei, Ting; Yu, Yue; Yuan, Fang; Jiao, Bo; Hou, Xun

    2016-04-01

    Herein, we reported a series of deep-blue-emitting naphthyl-functionalized oligophenyls as new organic laser active materials with tunable wavelength from 385 to 410 nm in solid state. Introduction of peripheral naphthyl into the oligophenyls enabled the great sterical dimensions due to the prominent steric hindrance but not destroyed the molecular conjugation. We assumed that it would suppress the π-π stacking efficiently, driving by intermolecular interaction, to hinder crystallization in solid films. Finally, the neat films of naphthyl-functionalized oligophenyls demonstrated amorphous state compared to the polycrystalline state of oligophenyls. Thus, naphthyl-functionalized oligophenyls displayed high emission quantum yield (22-35%) in solid state neat films. In addition, these molecules possessed large oscillator strength and radiative decay rate, as predicted by the theoretical analysis. The outstanding photophysical properties and amorphous films render naphthyl-functionalized oligophenyls a new class of optical gain media in solid state.

  15. Observation of self-amplified spontaneous emission in the wavelength range from 80 to 180 nm at the TESLA test facility FEL at DESY

    International Nuclear Information System (INIS)

    The first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet range between 80 and 180 nm wavelength is presented. The observed FEL gain (typically above 1000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations are discussed. Some accelerator issues are covered, and the future plans for the TESLA Test Facility (TTF) FEL are mentioned

  16. Spontaneous and amplified radiation at the initial stage of a SASE FEL

    International Nuclear Information System (INIS)

    At the initial stage of a self-amplified spontaneous emission (SASE) free-electron laser (FEL), spontaneous undulator radiation in certain experimental configurations can dominate the amplified signal over an extended undulator distance. In this paper they study both the spontaneous and the amplified radiation in the framework of the paraxial wave equation and determine the transition from the dominance of spontaneous emission to exponential amplification. They compare theoretical expectations with SASE simulation codes GINGER and GENESIS

  17. Pulsed amplified spontaneous Raman emission at 2.2 μm in silica-based fiber

    Science.gov (United States)

    Jiang, Huawei; Zhang, Lei; Yang, Xuezong; Yu, Ting; Feng, Yan

    2016-04-01

    All-fiber source at 2.2 μm is investigated with amplified spontaneous Raman scattering process in highly Ge-doped silica fiber. By optimizing the gain fiber length, the second-order Raman Stokes light at 2.43 μm is suppressed and 3 W first-order Raman Stokes light at 2.2 μm is obtained with a homemade 2-μm Q-switched Tm3+-doped fiber laser as pump source. The conversion efficiency is 35.9 % from 2.0 to 2.2 μm, and the peak power of the 2.2-μm laser is about 400 W.

  18. High amplified spontaneous emission contrast of 1011 in a Nd:glass laser based on a hybrid double chirped pulse amplification scheme

    International Nuclear Information System (INIS)

    By using a Ti:sapphire-Nd:glass hybrid double chirped pulse amplification scheme and a pulse cleaner based on optical parametric amplification and second harmonic generation, we demonstrate high amplified spontaneous emission (ASE) contrast at 1053 nm. The optimized ASE temporal contrast of the output pulse is about 1011 at about 160 ps before the main peak with an output of 140 mJ/500 fs. And the potential of 10 J level output with high ASE contrast is demonstrated in a laser system with attenuated injection. (paper)

  19. Spectroscopic studies, fluorescence quenching by molecular oxygen and amplified spontaneous emission of 1,4-bis [2-(2-pyridyl) vinyl] benzene (P2VB) diolefinic laser dye

    Science.gov (United States)

    El-Daly, Samy A.; Ebeid, E. M.

    2014-04-01

    The UV-visible electronic absorption spectra, molar absorptivity, fluorescence spectra, fluorescence quantum yield and excited state lifetime of 1,4-bis [2-(2-pyridyl) vinyl] benzene P2VB were measured in different solvents. The fluorescence quenching of P2VB by molecular oxygen was also studied using lifetime measurements. A 2 × 10-4 mol dm-3 solution of P2VB in dimethyl formamide (DMF) gave amplified spontaneous emission (ASE) in blue spectral region with emission maximum at 420 nm upon pumping by 337.1 nitrogen laser pulse. The photochemical quantum yields (ϕc) of trans-cis photoisomerization of P2VB were calculated in different organic solvents. The photoreactivity of P2VB are also studied PMMA matrix.

  20. Simulation of all-optical logic NOR gate based on two-photon absorption with semiconductor optical amplifier-assisted Mach-Zehnder interferometer with the effect of amplified spontaneous emission

    Science.gov (United States)

    Kotb, Amer

    2015-05-01

    The performance of an all-optical NOR gate is numerically simulated and investigated. The NOR Boolean function is realized by using a semiconductor optical amplifier (SOA) incorporated in Mach-Zehnder interferometer (MZI) arms and exploiting the nonlinear effect of two-photon absorption (TPA). If the input pulse intensities is adjusting to be high enough, the TPA-induced phase change can be larger than the regular gain-induced phase change and hence support ultrafast operation in the dual rail switching mode. The numerical study is carried out by taking into account the effect of the amplified spontaneous emission (ASE). The dependence of the output quality factor ( Q-factor) on critical data signals and SOAs parameters is examined and assessed. The obtained results confirm that the NOR gate implemented with the proposed scheme is capable of operating at a data rate of 250 Gb/s with logical correctness and high output Q-factor.

  1. Real-time monitoring and fault locating using amplified spontaneous emission noise reflection for tree-structured Ethernet passive optical networks

    Science.gov (United States)

    Naim, Nani Fadzlina; Ab-Rahman, Mohammad Syuhaimi; Kamaruddin, Nur Hasiba; Bakar, Ahmad Ashrif A.

    2013-09-01

    Nowadays, optical networks are becoming dense while detecting faulty branches in the tree-structured networks has become problematic. Conventional methods are inconvenient as they require an engineer to visit the failure site to check the optical fiber using an optical time-domain reflectometer. An innovative monitoring technique for tree-structured network topology in Ethernet passive optical networks (EPONs) by using the erbium-doped fiber amplifier to amplify the traffic signal is demonstrated, and in the meantime, a residual amplified spontaneous emission spectrum is used as the input signal to monitor the optical cable from the central office. Fiber Bragg gratings with distinct center wavelengths are employed to reflect the monitoring signals. Faulty branches of the tree-structured EPONs can be identified using a simple and low-cost receiver. We will show that this technique is capable of providing monitoring range up to 32 optical network units using a power meter with a sensitivity of -65 dBm while maintaining the bit error rate of 10-13.

  2. The propagation of a strong x-ray pulse followed by pulse slowdown and compression, amplified spontaneous emission and lasing without inversion

    International Nuclear Information System (INIS)

    We study self-seeded stimulated resonant x-ray Raman scattering and show a 20-fold compression of the strong XFEL pulse propagating through the resonant medium of atomic argon with the frequency (244.3 eV) tuned to the 2p3/2-4s resonance. The strong x-ray pulse inverts the medium and produces an extensive ringing tail which widens the power spectrum. Newly created seed field triggers the Stokes channel 3s-2p3/2 of amplified spontaneous emission. The population inversions are quenched for longer propagation distances where lasing without inversion enhances the Stokes component. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. The group velocity is decreased up to 78% of the speed of light in vacuum. (fast track communication)

  3. Solvent-vapour treatment induced performance enhancement of amplified spontaneous emission based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1, 4-phenylene vinylene

    International Nuclear Information System (INIS)

    In this work, performance enhancements of amplified spontaneous emission (ASE) from poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1, 4-phenylene vinylene] (MEH-PPV) have been achieved via solvent vapour treatment. Correlations between the morphology of the film and the optical performance of polymer-based ASE are investigated. The active layers are characterised by atomic force microscopy and optical absorption. The results show that the solvent-vapour treatment can induce the MEH-PPV self-organisation into an ordered structure with a smooth surface, leading to enhanced optical gain. Thus the solvent-vapour treatment is a good method for improving the optical properties of the MEH-PPV. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites

    KAUST Repository

    Priante, D.

    2015-02-23

    We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic radiative transitions related to grain size inhomogeneity were identified. Both transitions led to PL spectra broadening as a result of concurrent blue and red shifts of these excitonic peaks. The red-shifted bound-excitonic peak dominated at high PL excitation led to a true-green wavelength of 553nm for CH3NH3PbBr3 powders that are encapsulated in polydimethylsiloxane. Amplified spontaneous emission was eventually achieved for an excitation threshold energy of approximately 350μJ/cm2. Our results provide a platform for potential extension towards a true-green light-emitting device for solid-state lighting and display applications.

  5. Transform-Limited X-Ray Pulse Generation from a High Brightness Self-Amplified Spontaneous Emission Free-Electron Laser

    CERN Document Server

    McNeil, B W J; Dunning, D J

    2012-01-01

    A method to achieve High-Brightness Self-Amplified Spontaneous Emission (HB-SASE) in the Free Electron Laser (FEL) is described. The method uses repeated non-equal electron beam delays to de-localise the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated using linear theory and numerical simulations that the radiation coherence length can be increased by approximately two orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft X-ray and near transform-limited pulses in the hard X-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research.

  6. Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing

    International Nuclear Information System (INIS)

    We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p3/2-4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p3/2 and 3s-2p3/2, which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p3/2. The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

  7. Controlling spontaneous emission

    DEFF Research Database (Denmark)

    Lodahl, Peter

    Control over spontaneous emission of light is of great importance in quantum optics. It is essential for diverse applications such as miniature lasers, light-emitting diodes, and single-photon sources for quantum information. We present experimental studies on spontaneous emission of CdSe quantum...... dots (QDs) embedded in 3D photonic crystals consisting of air spheres in titanium dioxide. Performing time-resolved experiments, we show that the photonic crystals control the emission decay rate of excitons confined in the QDs1,2. By varying the lattice parameter of the photonic crystals, we...

  8. Quantum Maxwell-Bloch equations for spontaneous emission in optical semiconductor devices

    OpenAIRE

    Hess, Ortwin; Hofmann, Holger F.

    1998-01-01

    We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous optical semiconductor devices taking into account the quantum noise effects which cause spontaneous emission and amplified spontaneous emission. Analytical expressions derived from the QMBE are presented for the spontaneous emission factor beta and the far field pattern of amplified spontaneous emission in broad area quantum well lasers.

  9. Air-Stable Surface-Passivated Perovskite Quantum Dots for Ultra-Robust, Single- and Two-Photon-Induced Amplified Spontaneous Emission

    KAUST Repository

    Pan, Jun

    2015-12-01

    We demonstrate ultra-air- and photostable CsPbBr3 quantum dots (QDs) by using an inorganic–organic hybrid ion pair as the capping ligand. This passivation approach to perovskite QDs yields high photoluminescence quantum yield with unprecedented operational stability in ambient conditions (60 ± 5% lab humidity) and high pump fluences, thus overcoming one of the greatest challenges impeding the development of perovskite-based applications. Due to the robustness of passivated perovskite QDs, we were able to induce ultrastable amplified spontaneous emission (ASE) in solution processed QD films not only through one photon but also through two-photon absorption processes. The latter has not been observed before in the family of perovskite materials. More importantly, passivated perovskite QD films showed remarkable photostability under continuous pulsed laser excitation in ambient conditions for at least 34 h (corresponds to 1.2 × 108 laser shots), substantially exceeding the stability of other colloidal QD systems in which ASE has been observed.

  10. Amplified spontaneous emission and thermal management on a high average-power diode-pumped solid-state laser - the Lucia laser system

    International Nuclear Information System (INIS)

    The development of the laser triggered the birth of numerous fields in both scientific and industrial domains. High intensity laser pulses are a unique tool for light/matter interaction studies and applications. However, current flash-pumped glass-based systems are inherently limited in repetition-rate and efficiency. Development within recent years in the field of semiconductor lasers and gain media drew special attention to a new class of lasers, the so-called Diode Pumped Solid State Laser (DPSSL). DPSSLs are highly efficient lasers and are candidates of choice for compact, high average-power systems required for industrial applications but also as high-power pump sources for ultra-high intense lasers. The work described in this thesis takes place in the context of the 1 kilowatt average-power DPSSL program Lucia, currently under construction at the 'Laboratoire d'Utilisation des Laser Intenses' (LULI) at the Ecole Polytechnique, France. Generation of sub-10 nanosecond long pulses with energies of up to 100 joules at repetition rates of 10 hertz are mainly limited by Amplified Spontaneous Emission (ASE) and thermal effects. These limitations are the central themes of this work. Their impact is discussed within the context of a first Lucia milestone, set around 10 joules. The developed laser system is shown in detail from the oscillator level to the end of the amplification line. A comprehensive discussion of the impact of ASE and thermal effects is completed by related experimental benchmarks. The validated models are used to predict the performances of the laser system, finally resulting in a first activation of the laser system at an energy level of 7 joules in a single-shot regime and 6.6 joules at repetition rates up to 2 hertz. Limitations and further scaling approaches are discussed, followed by an outlook for the further development. (author)

  11. Wideband thulium–holmium-doped fiber source with combined forward and backward amplified spontaneous emission at 1600–2300 nm spectral band

    Czech Academy of Sciences Publication Activity Database

    Honzátko, Pavel; Baravets, Yauhen; Kašík, Ivan; Podrazký, Ondřej

    2014-01-01

    Roč. 39, č. 12 (2014), s. 3650-3653. ISSN 0146-9592 R&D Projects: GA ČR(CZ) GAP205/11/1840 Institutional support: RVO:67985882 Keywords : Bandwidth * Spontaneous emission * Holmium Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.292, year: 2014

  12. Shell theorem for spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter; Stobbe, Søren

    2013-01-01

    We investigate spontaneous emission from excitons beyond the point source dipole approximation and show how the symmetry of the exciton wave function plays a crucial role. We find that for spherically symmetric wave functions, the Purcell effect is independent of the wave function size and...... therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....

  13. Ion cyclotron emission by spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Da Costa, O. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Gresillon, D. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1994-07-01

    The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs.

  14. Controlled spontaneous emission in erbium-doped microphotonic materials

    NARCIS (Netherlands)

    Kalkman, Jeroen

    2005-01-01

    Erbium is a rare-earth metal that, when incorporated in a solid, can emit light at a wavelength of 1.5 μm. It plays a key role in current day telecommunication technology as the principle ingredient of optical fiber amplifiers. In this thesis the control of the Er spontaneous emission in three diffe

  15. Cooperative spontaneous emission in nonuniform media

    OpenAIRE

    Rudziński, Adam

    2010-01-01

    The subject of this paper is modification of cooperative spontaneous emission by a nonuniform medium, with nonuniform distributions of electromagnetic field. A brief analyzis is presented and it is postulated, that if spontaneous emission from an atom is strongly suppressed, cooperative emission with another atom may be a preferred emission channel and counteract the suppression.

  16. Noise in Optical Amplifiers

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1997-01-01

    Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

  17. Spontaneous Emission in Nonlocal Materials

    CERN Document Server

    Ginzburg, Pavel; Nasir, Mazhar E; Olvera, Paulina Segovia; Krasavin, Alexey V; Levitt, James; Hirvonen, Liisa M; Wells, Brian; Suhling, Klaus; Richards, David; Podolskiy, Viktor A; Zayats, Anatoly V

    2016-01-01

    Light-matter interactions can be dramatically modified by the surrounding environment. Here we report on the first experimental observation of molecular spontaneous emission inside a highly nonlocal metamaterial based on a plasmonic nanorod assembly. We show that the emission process is dominated not only by the topology of its local effective medium dispersion, but also by the nonlocal response of the composite, so that metamaterials with different geometric parameters but the same local effective medium properties exhibit different Purcell factors. A record-high enhancement of a decay rate is observed, in agreement with the developed quantitative description of the Purcell effect in a nonlocal medium. An engineered material nonlocality introduces an additional degree of freedom into quantum electrodynamics, enabling new applications in quantum information processing, photo-chemistry, imaging, and sensing.

  18. Amplified spontaneous emission from ZnO in n-ZnO/ZnO nanodots-SiO(2) composite/p-AlGaN heterojunction light-emitting diodes.

    Science.gov (United States)

    Shih, Ying Tsang; Wu, Mong Kai; Li, Wei Chih; Kuan, Hon; Yang, Jer Ren; Shiojiri, Makoto; Chen, Miin Jang

    2009-04-22

    This study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at lambda~380 nm in the n-ZnO/ZnO nanodots-SiO(2) composite/p- Al(0.12)Ga(0.88)N heterojunction light-emitting diode. A SiO(2) layer embedded with ZnO nanodots was prepared on the p-type Al(0.12)Ga(0.88)N using spin-on coating of SiO(2) nanoparticles followed by atomic layer deposition (ALD) of ZnO. An n-type Al-doped ZnO layer was deposited upon the ZnO nanodots-SiO(2) composite layer also by the ALD technique. High-resolution transmission electron microscopy (HRTEM) reveals that the ZnO nanodots embedded in the SiO(2) matrix have diameters of 3-8 nm and the wurtzite crystal structure, which allows the transport of carriers through the thick ZnO nanodots-SiO(2) composite layer. The high quality of the n-ZnO layer was manifested by the well crystallized lattice image in the HRTEM picture and the low-threshold optically pumped stimulated emission. The low refractive index of the ZnO nanodots-SiO(2) composite layer results in the increase in the light extraction efficiency from n-ZnO and the internal optical feedback of UV EL into n-ZnO layer. Consequently, significant enhancement of the UV EL intensity and super-linear increase in the EL intensity, as well as the spectral narrowing, with injection current were observed owing to ASE in the n-ZnO layer. PMID:19420563

  19. Dynamics of spontaneous otoacoustic emissions

    Science.gov (United States)

    Bergevin, Christopher; Salerno, Anthony

    2015-12-01

    Spontaneous otoacoustic emissions (SOAEs) have become a hallmark feature in modern theories of an `active' inner ear, given their numerous correlations to auditory function (e.g., threshold microstructure, neurophysiological tuning curves), near universality across tetrapod classes, and physiological correlates at the single hair cell level. However, while several different classes of nonlinear models exist that describe the mechanisms underlying SOAE generation (e.g., coupled limit-cycle oscillators, global standing waves), there is still disagreement as to precisely which biophysical concepts are at work. Such is further compounded by the idiosyncratic nature of SOAEs: Not all ears emit, and when present, SOAE activity can occur at seemingly arbitrary frequencies (though always within the most sensitive range of the audiogram) and in several forms (e.g., peaks, broad `baseline' plateaus). The goal of the present study was to develop new signal processing and stimulation techniques that would allow for novel features of SOAE activity to be revealed. To this end, we analyzed data from a variety of different species: human, lizard, and owl. First, we explored several strategies for examining SOAE waveforms in the absence of external stimuli to further ascertain what constitutes `self-sustained sinusoids' versus `filtered noise'. We found that seemingly similar peaks in the spectral domain could exhibit key differences in the time domain, which we interpret as providing critical information about the underlying oscillators and their coupling. Second, we introduced dynamic stimuli (swept-tones, tone bursts) at a range of levels, whose interaction with SOAEs could be visualized in the time-frequency domain. Aside from offering a readily accessible way to visualize many previously reported effects (e.g., entrainment, facilitation), we observed several new features such as subharmonic distortion generation and competing pulling/pushing effects when multiple tones were

  20. Spontaneous emission from active dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    engineered due to the dependence of the emission rate on the location and polarisation of the emitters in the structure. This paper addresses the methods of quantum electrodynamics of dielectric media which enable calculation of the local rate of spontaneous emission in active microstructures....

  1. Ultrafast spontaneous emission source using plasmonic nanoantennas

    Science.gov (United States)

    Hoang, Thang B.; Akselrod, Gleb M.; Argyropoulos, Christos; Huang, Jiani; Smith, David R.; Mikkelsen, Maiken H.

    2015-07-01

    Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1-10 ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ~50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

  2. Enhanced spontaneous emission factor for microcavity lasers

    Institute of Scientific and Technical Information of China (English)

    Xiaoxia Zhang; Wei Pan

    2008-01-01

    The microcavity and the influence of nonradiative recombination can control spontaneous emission. An analytic resolution of rate equation is studied for microcavity lasers. The relationship between output prop- erties and structural parameters of multi-quantum wells (MQWs) is obtained. One of the most important consequences of the incrcased spontaneous emission factor is the reduction of laser threshold. It is found that the characteristic curve of a "thresholdless" laser is strongly nonradiative depopulation-dependent. The light output is increased by the enhanced well number and the reduced width. In particular, there is an optimal well number corresponding to the lowest threshold current density for MQW structure in the microcavity lasers.

  3. Silicon photonic crystals and spontaneous emission

    NARCIS (Netherlands)

    Dood, Michiel Jacob Andries de

    2002-01-01

    Photonic crystals, i.e. materials that have a periodic variation in refractive index, form an interesting new class of materials that can be used to modify spontaneous emission and manipulate optical modes in ways that were impossible so far. This thesis is divided in three parts. Part I discusses

  4. Photonic Crystals-Inhibited Spontaneous Emission: Optical Antennas-Enhanced Spontaneous Emission

    Science.gov (United States)

    Yablonovitch, Eli

    Photonic crystals are also part of everyday technological life in opto-electronic telecommunication devices that provide us with internet, cloud storage, and email. But photonic crystals have also been identified in nature, in the coloration of peacocks, parrots, chameleons, butterflies and many other species.In spite of its broad applicability, the original motivation of photonic crystals was to create a ``bandgap'' in which the spontaneous emission of light would be inhibited. Conversely, the opposite is now possible. The ``optical antenna'' can accelerate spontaneous emission. Over 100 years after the radio antenna, we finally have tiny ``optical antennas'' which can act on molecules and quantum dots. Employing optical antennas, spontaneous light emission can become faster than stimulated emission.

  5. Mapping quantum state dynamics in spontaneous emission.

    Science.gov (United States)

    Naghiloo, M; Foroozani, N; Tan, D; Jadbabaie, A; Murch, K W

    2016-01-01

    The evolution of a quantum state undergoing radiative decay depends on how its emission is detected. If the emission is detected in the form of energy quanta, the evolution is characterized by a quantum jump to a lower energy state. In contrast, detection of the wave nature of the emitted radiation leads to different dynamics. Here, we investigate the diffusive dynamics of a superconducting artificial atom under continuous homodyne detection of its spontaneous emission. Using quantum state tomography, we characterize the correlation between the detected homodyne signal and the emitter's state, and map out the conditional back-action of homodyne measurement. By tracking the diffusive quantum trajectories of the state as it decays, we characterize selective stochastic excitation induced by the choice of measurement basis. Our results demonstrate dramatic differences from the quantum jump evolution associated with photodetection and highlight how continuous field detection can be harnessed to control quantum evolution. PMID:27167893

  6. Spontaneous emission in the ellipsoidal nanocrystals

    Institute of Scientific and Technical Information of China (English)

    K.K.Pukhov

    2009-01-01

    The equation was presented for the spontaneous emission rate Anano of the two-level optical centers in the subwavelength ellipsoidal nanocrystals embedded in a dielectric medium.An important result was that the ratio Anano/Abulk could be estimated without recourse to a particular local-field model.On the ground of this equation the expression was derived for linestrength of electric-dipole transition in trivalent rare-earth ions.The applicability of the Judd-Ofelt equation for nanoparticles was discussed.

  7. Spontaneous light emission from fibers in MINOS

    International Nuclear Information System (INIS)

    We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days

  8. Ultrafast nonlocal control of spontaneous emission

    CERN Document Server

    Jin, Chao-Yuan; Swinkels, Milo Y; Hoang, Thang B; Midolo, Leonardo; van Veldhoven, Peter J; Fiore, Andrea

    2013-01-01

    Solid-state cavity quantum electrodynamics systems will form scalable nodes of future quantum networks, allowing the storage, processing and retrieval of quantum bits, where a real-time control of the radiative interaction in the cavity is required to achieve high efficiency. We demonstrate here the dynamic molding of the vacuum field in a coupled-cavity system to achieve the ultrafast nonlocal modulation of spontaneous emission of quantum dots in photonic crystal cavities, on a timescale of ~200 ps, much faster than their natural radiative lifetimes. This opens the way to the ultrafast control of semiconductor-based cavity quantum electrodynamics systems for application in quantum interfaces and to a new class of ultrafast lasers based on nano-photonic cavities.

  9. Spontaneous emission of polaritons from a Bose-Einstein condensate

    OpenAIRE

    Marzlin, Karl-Peter; Zhang, Weiping

    1999-01-01

    We study the spontaneous emission of a partially excited Bose-Einstein condensate composed of two-level atoms. The formation of polaritons induced by the ground-state part of the condensate leads to an avoided crossing in the photon spectrum. This avoided crossing acts similarly to a photonic band gap and modifies the spontaneous emission rate.

  10. Spontaneous emission of two interacting atoms near an interface

    Institute of Scientific and Technical Information of China (English)

    Dehua Wang

    2009-01-01

    The spontaneous emission rate of two interacting excited atoms near a dielectric interface is studied using the photon closed-orbit theory and the dipole image method.The total emission rate of one atom during the emission process is calculated as a function of the distance between the atom and the interface.The results suggest that the spontaneous emission rate depends not only on the atomic-interface distances,but also on the orientation of the two atomic dipoles and the initial distance between the two atoms.The oscillation in the spontaneous emission rate is caused by the interference between the outgoing electromagnetic wave emitted from one atom and other waves arriving at this atom after traveling along various classical orbits.Each peak in the Fourier transformed spontaneous emission rate corresponds with one action of photon classical orbit.

  11. Spontaneous Otoacoustic Emissions in Tinnitus Patients

    Institute of Scientific and Technical Information of China (English)

    SHI Yongbing; William Martin

    2006-01-01

    Otoacoustic emissions (OAEs) are believed to be the products of active cochlear mechanics. They are generally associated with relatively intact outer hair cell function. OAEs usually decrease or become undetectable when hearing loss of cochlear origin exceeds 40-50 dB HL. Subjective tinnitus is a perception of sound without detectable corresponding source. It is most often seen in patients with hearing loss. It is also frequently seen in patients with head injuries. Studies have suggested that the prevalence of spontaneous otoacoustic emissions(SOAEs) is lower in patients with hearing loss and tinnitus than in normal population. There have also been reports on association between tinnitus and SOAEs of unusually high amplitudes, which can be controlled by aspirin administration. The current paper is a preliminary review of clinical data collected from a group oftinnitus patients in an attempt to elucidate on the relationship between SOAEs and tinnitus from a clinical point of view. Audiometric, tinnitus and SOAE data from 59 patients seen at the Oregon Health & Science University Tinnitus Clinic were retrospectively studied. Fifty-four of these 59 patients showed sensorineural hearing loss of various degrees at the time of evaluation, mostly affecting high frequencies. SOAEs were detected in 26 ears (22%) of 1 8 patients(30.5%). There was no difference in SOAE prevalence between male and female patients. SOAEs were recorded in four of the five patients whose pure tone thresholds were within normal limits up to 8000 Hz. SOAEs appeared to be recorded at a higher rate in patients whose tinnitus started following motor vehicle accidents or head injuries(5/10) than in other patients.Time course of tinnitus did not appear to affect SOAE detection rate. There were no correlations between SOAE frequency and matched tinnitus pitch or frequency of maximum hearing loss. Significance of these findings is discussed.

  12. Controlling spontaneous emission with plasmonic optical patch antennas

    OpenAIRE

    Belacel, C.; Habert, B.; Bigourdan, F.; Marquier, F.; Hugonin, J.-P.; Michaelis de Vasconcellos, S.; Lafosse, X.; Coolen, L; Schwob, C.; Javaux, C; Dubertret, B.; Greffet, J. -J.; Senellart, P.; Maitre, A.

    2012-01-01

    We experimentally demonstrate the control of the spontaneous emission rate and the radiation pattern of colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists of a thin gold microdisk 30 nm above a thick gold layer. The emitters are shown to radiate through the entire patch antenna in a highly directional and vertical radiation pattern. Strong acceleration of spontaneous emission is observed, depending of the antenna size. Considering the double...

  13. Spontaneous Emission Control in a Tunable Hybrid Photonic System

    OpenAIRE

    Frimmer, M.; Koenderink, A. F.

    2012-01-01

    We experimentally demonstrate control of the rate of spontaneous emission in a tunable hybrid photonic system that consists of two canonical building blocks for spontaneous emission control, an optical antenna and a mirror, each providing a modification of the local density of optical states (LDOS). We couple fluorophores to a plasmonic antenna to create a superemitter with an enhanced decay rate. In a superemitter analog of the seminal Drexhage experiment we probe the LDOS of a nanomechanica...

  14. Amplified radio emission from cosmic ray air showers in thunderstorms

    CERN Document Server

    Buitink, S; Asch, T; Badea, F; Bähren, L; Bekk, K; Bercuci, A; Bertaina, M; Biermann, P L; Blumer, J; Bozdog, H; Brancus, I M; Bruggemann, M; Buchholz, P; Butcher, H; Chiavassa, A; Cossavella, F; Daumiller, K; Di Pierro, F; Doll, P; Engel, R; Falcke, H; Gemmeke, H; Ghia, P L; Glasstetter, R; Grupen, C; Haungs, A; Heck, D; Hörandel, J R; Horneffer, A; Huege, T; Kampert, K H; Kolotaev, Y; Krömer, O; Kuijpers, J; Lafebre, S; Mathes, H J; Mayer, H J; Meurer, C; Milke, J; Mitrica, B; Morello, C; Navarra, G; Nehls, S; Nigl, A; Obenland, R; Oehlschläger, J; Ostapchenko, S; Over, S; Petcu, M; Petrovic, J; Pierog, T; Plewnia, S; Rebel, H; Risse, A; Roth, M; Schieler, H; Sima, O; Singh, K; Stumpert, M; Toma, G; Trinchero, G C; Ulrich, H; Van Buren, J; Walkowiak, W; Weindl, A; Wochele, J; Zabierowski, J; Zensus, J A; Zimmermann, D; Buitink, Stijn

    2007-01-01

    Cosmic ray air showers produce radio emission, consisting in large part of geosynchrotron emission. Since the radiation mechanism is based on particle acceleration, the atmospheric electric field can play an important role. Especially inside thunderclouds large electric fields can be present. We examine the contribution of an electric field to the emission mechanism theoretically and experimentally. Two mechanisms of amplification of radio emission are considered: the acceleration radiation of the shower particles and the radiation from the current that is produced by ionization electrons moving in the electric field. We selected and evaluated LOPES data recorded during thunderstorms, periods of heavy cloudiness and periods of cloudless weather. We find that during thunderstorms the radio emission can be strongly enhanced. No amplified pulses were found during periods of cloudless sky or heavy cloudiness, suggesting that the electric field effect for radio air shower measurements can be safely ignored during ...

  15. Spontaneous emission in Cherenkov FEL devices

    International Nuclear Information System (INIS)

    The main features of the spectral characteristics of the spontaneously emitted Cherenkov light in circular and rectangular wave-guides filled with dielectric are discussed. The characteristics of the radiation emitted by an electron beam moving near and parallel to the surface of a dielectric slab are also analysed. Finally, the relevance of these results to a possible FEL-Cherenkov operation is briefly discussed

  16. Surface plasmon enhancement of spontaneous emission in graphene waveguides

    CERN Document Server

    Cuevas, Mauro

    2016-01-01

    This work analyzes the spontaneous emission of a single emitter placed near the graphene waveguide formed by two parallel graphene monolayers, with an insulator spacer layer. In this case, the eigenmodes supported by the structure, such as surface plasmon and wave guided modes, provide decay channels for the electric dipole placed close to the waveguide. We calculated the contribution to the decay rate of symmetric and antisymmetric eigenmodes as a function of frequency and the orientation of the emitter. Our results show that the modi?cation of the spontaneous emission due to excitation of guided modes is much lower than the corresponding decays through the excitation of symmetric and antisymmetric surface plasmons, for which, the spontaneous emission is dramatically enhanced. As a consequence of the high con?nement of surface plasmons in the graphene waveguide, we found that the decay rate of the emitter with vertical orientation (with respect to graphene sheets) is twice the corresponding decay of the same...

  17. Spontaneous Emission Enhancement at Finite-length Metal

    DEFF Research Database (Denmark)

    Filonenko, K.; Willatzen, Morten; Bordo, V.

    2013-01-01

    We study spontaneous emission enhancement of a two-level atomic emitter placed in a dielectric medium near a finite-length cylindrical metal nanowire. We calculate the dependence of the Purcell factor and the normalized decay rate to a continuous spectrum on the nanowire radius for several emitter...... transition wavelengths and different orientations of the transition dipole moment. For a particular transition wavelength we calculate the dependence of these quantities as well as the β-factor on the emitter distance from the nanowire and the nanowire radius. The obtained results demonstrate that the...... spontaneous emission characteristics exhibit significant differences as compared to the case of an infinite wire....

  18. Controlling spontaneous emission with plasmonic optical patch antennas

    CERN Document Server

    Belacel, C; Bigourdan, F; Marquier, F; Hugonin, J -P; de Vasconcellos, S Michaelis; Lafosse, X; Coolen, L; Schwob, C; Javaux, C; Dubertret, B; Greffet, J -J; Senellart, P; Maitre, A

    2012-01-01

    We experimentally demonstrate the control of the spontaneous emission rate and the radiation pattern of colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists of a thin gold microdisk 30 nm above a thick gold layer. The emitters are shown to radiate through the entire patch antenna in a highly directional and vertical radiation pattern. Strong acceleration of spontaneous emission is observed, depending of the antenna size. Considering the double dipole structure of the emitters, this corresponds to a Purcell factor up to 80 for dipoles perpendicular to the disk.

  19. Full control of spontaneous emission in confined Tamm plasmon structures

    CERN Document Server

    Gazzano, O; Gauthron, K; Symonds, C; Bloch, J; Voisin, P; Bellessa, J; Lemaitre, A; Senellart, P

    2011-01-01

    We demonstrate the possibility to strongly confine the optical field by depositing a micron sized metallic disk on a planar interferential mirror. Zero dimensional Tamm plasmon modes are evidenced both experimentally and theoretically, with a lateral confinement limited to the disk area and strong coupling to TE polarized fields. Single quantum dots deterministically coupled to these modes are shown to experience acceleration of their spontaneous emission when spectrally resonant with the mode. For quantum dots spectrally detuned from the confined Tamm Plasmon mode, an inhibition of spontaneous emission by a factor 40 is observed, a record value in the optical domain.

  20. Spontaneous Emission of Charged Bosons from Supercritical Point Charges

    CERN Document Server

    Kim, Sang Pyo

    2013-01-01

    We study the spontaneous emission of charged bosons from supercritical Coulomb potentials and charged black holes. We find the exact emission rate from the Bogoliubov transformation by applying the tunneling boundary condition on the Jost functions at the asymptotic boundaries. The emission rate for charged bosons in the supercritical Coulomb potential increases as the charge $Z\\alpha > 1/2$ of the superatom and the energy of the bosons increase but is suppressed for large angular momenta. We discuss physical implications of the emission of charged bosons from superatoms and charged black holes.

  1. Spontaneous two photon emission from a single quantum dot

    CERN Document Server

    Ota, Y; Kumagai, N; Arakawa, Y

    2011-01-01

    Spontaneous two photon emission from a solid-state single quantum emitter is observed. We investigated photoluminescence from the neutral biexciton in a single semiconductor quantum dot coupled with a high Q photonic crystal nanocavity. When the cavity is resonant to the half energy of the biexciton, the strong vacuum field in the cavity inspires the biexciton to simultaneously emit two photons into the mode, resulting in clear emission enhancement of the mode. Meanwhile, suppression was observed of other single photon emission from the biexciton, as the two photon emission process becomes faster than the others at the resonance.

  2. Demonstration of Weak Measurement Based on Atomic Spontaneous Emission

    OpenAIRE

    Shomroni, Itay; Bechler, Orel; Rosenblum, Serge; Dayan, Barak

    2013-01-01

    We demonstrate a new type of weak measurement based on the dynamics of spontaneous emission. The pointer in our scheme is given by the Lorentzian distribution characterizing atomic exponential decay via emission of a single photon. We thus introduce weak measurement, so far demonstrated nearly exclusively with laser beams and Gaussian statistics, into the quantum regime of single emitters and single quanta, enabling the exploitation of a wide class of sources that are abundant in nature. We d...

  3. Spontaneous emission of non-dispersive Rydberg wave packets

    OpenAIRE

    Delande, Dominique; Zakrzewski, Jakub

    1998-01-01

    Non dispersive electronic Rydberg wave packets may be created in atoms illuminated by a microwave field of circular polarization. We discuss the spontaneous emission from such states and show that the elastic incoherent component (occuring at the frequency of the driving field) dominates the spectrum in the semiclassical limit, contrary to earlier predictions. We calculate the frequencies of single photon emissions and the associated rates in the "harmonic approximation", i.e. when the wave p...

  4. Spontaneous emission of quantum dots in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren; Garcia-Fernández, David; Smolka, Stephan; Lodahl, Peter

    2010-01-01

    We report on the enhancement of the spontaneous emission rate of single semiconductor quantum dots embedded in a photonic crystal waveguide with engineered disorder. Random high-Q cavities, that are signature of Anderson localization, are measured in photoluminescence experiments and appear in the...

  5. Spontaneous emission effects in optically pumped x-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Smetanin, I.V.; Grigor`ev, S.V. [P.N. Lebedev Physics Institute, Moscow (Russian Federation)

    1995-12-31

    An effect of spontaneous emission in both quantum and classical regimes of the optically pumped X-ray free electron laser (FEL) in investigated. The quantum properties of an FEL are determined by the ratio of the separation {h_bar} between the absorption and emission lines (i.e. the quanta emitted) and their effective width {Delta}{epsilon} {eta}={h_bar}/{Delta}{epsilon}. In the conventional classical regime {eta} {much_lt} 1 an electron emits and absorbes a great number of shortwavelength photons over the interaction region, the gain in FEL being the result of these competitive processes. In the quantum limit {eta} {much_gt} 1 the emission and absorption lines are completely separated and thus the FEL becomes a two-level quantum oscillator with a completely inverted active medium. Spontaneous emission causes the electron to leave the range of energies where resonant interaction with the laser field occurs, thus effectively reducing the number of particles that take part in generating the induced X-ray signal. This effect is found to be crucial for lasing in optically pumped X-ray FEL. The characteristic relaxation times are calculated for both classical and quantum FEL regimes. It is shown that spontaneous emission results in FEL electron beam threshold current, which is of rather high value. An optimal range of pumping laser intensities is determined.

  6. Emissivity of condensed phases from the spontaneous emission spectrum

    International Nuclear Information System (INIS)

    The method of determining the temperature and spectral emissivity of substances unavailable for direct contact is described. Potentialities of the method were demonstrated using incandescent lamps with emitting filaments made of tungsten, rhenium and tantalum. Accuracy of determination of the temperature and spectral emissivity (in the range of spectrum 0.9-2.1 μm) made up 1 and 10% respectively

  7. Pump to signal noise transfer in parametric fiber amplifiers

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Rottwitt, Karsten; Peucheret, Christophe; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard; Svane, Ask Sebastian; Andersen, Lasse Mejling; Cristofori, Valentina

    2010-01-01

    Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal.......Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal....

  8. "OPERA superluminal neutrinos explained by spontaneous emission and stimulated absorption"

    CERN Document Server

    Torrealba, Rafael

    2011-01-01

    In this work it is shown, that for short 3ns neutrino pulses reported by OPERA, a relativistic shape deforming effect of the neutrino distribution function due to spontaneous emission, produces an earlier arrival of 65.8ns in agreement with the reported 62.1ns\\pm 3.7ns, with a RMS of 16.4ns explaining the apparent superluminal effect. It is also shown, that early arrival of long 10500ns neutrinos pulse to Gran Sasso, by 57.8ns with respect to the speed of light, could be explained by a shape deforming effect due to a combination of stimulated absorption and spontaneous emission, while traveling by the decay tunnel that acts as a LASER tube.

  9. Transformation quantum optics: designing spontaneous emission using coordinate transformations

    Science.gov (United States)

    Zhang, Jingjing; Wubs, Martijn; Ginzburg, Pavel; Wurtz, Gregory; Zayats, Anatoly V.

    2016-04-01

    Spontaneous decay is a fundamental quantum property of emitters that can be controlled in a material environment via modification of the local density of optical states (LDOS). Here we use transformation optics methods in order to design required density of states and thus spontaneous emission (SE) rate. Specifically, we show that the SE rate can be either enhanced or suppressed using invisibility cloaks or gradient index lenses. Furthermore, the anisotropic material profile of the cloak enables the directional control of SE. We also discuss how the practical issues, such as dispersion and losses, affect the LDOS in complex materials. Tailoring SE properties using transformation optics approach provides an innovative way for designing emission properties in a complex material environment needed for the development of active nanophotonic devices.

  10. Transformation quantum optics: designing spontaneous emission using coordinate transformations

    International Nuclear Information System (INIS)

    Spontaneous decay is a fundamental quantum property of emitters that can be controlled in a material environment via modification of the local density of optical states (LDOS). Here we use transformation optics methods in order to design required density of states and thus spontaneous emission (SE) rate. Specifically, we show that the SE rate can be either enhanced or suppressed using invisibility cloaks or gradient index lenses. Furthermore, the anisotropic material profile of the cloak enables the directional control of SE. We also discuss how the practical issues, such as dispersion and losses, affect the LDOS in complex materials. Tailoring SE properties using transformation optics approach provides an innovative way for designing emission properties in a complex material environment needed for the development of active nanophotonic devices. (paper)

  11. Transformation quantum optics: designing spontaneous emission using coordinate transformations

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Wubs, Martijn; Ginzburg, Pavel;

    2016-01-01

    Spontaneous decay is a fundamental quantum property of emitters that can be controlled in a material environment via modification of the local density of optical states (LDOS). Here we use transformation optics methods in order to design required density of states and thus spontaneous emission (SE......) rate. Specifically, we show that the SE rate can be either enhanced or suppressed using invisibility cloaks or gradient index lenses. Furthermore, the anisotropic material profile of the cloak enables the directional control of SE. We also discuss how the practical issues, such as dispersion and losses......, affect the LDOS in complex materials. Tailoring SE properties using transformation optics approach provides an innovative way for designing emission properties in a complex material environment needed for the development of active nanophotonic devices....

  12. Are Einstein's transition probabilities for spontaneous emission constant in plasmas?

    Science.gov (United States)

    Griem, H. R.; Huang, Y. W.; Wang, J.-S.; Moreno, J. C.

    1991-01-01

    An investigation is conducted with a ruby laser to experimentally confirm the quenching of spontaneous emission coefficients and propose a mechanism for the phenomenon. Results of previous experiments are examined to determine the consistency and validity of interpretations of the spontaneous emissions. For the C IV 3s-3p and 2s-3p transitions, the line-intensity ratios are found to be dependent on the separation of the laser from the target. Density gradients and Stark broadening are proposed to interpret the results in a way that does not invalidate the Einstein A values. The interpretation is extended to C III and N V, both of which demonstrate similar changes in A values in previous experiments. The apparent quenching of Ar II by photon collisions is explained by Rabi oscillations and power broadening in the argon-ion laser cavity. It is concluded that the changes in A values cannot result from dense plasma effects.

  13. Spontaneous Emission Control in a Tunable Hybrid Photonic System

    CERN Document Server

    Frimmer, Martin

    2013-01-01

    We experimentally demonstrate control of the rate of spontaneous emission in a tunable hybrid photonic system that consists of two canonical building blocks for spontaneous emission control, an optical antenna and a mirror, each providing a modification of the local density of optical states (LDOS).We couple fluorophores to a plasmonic antenna to create a superemitter with an enhanced decay rate. In a superemitter analog of the seminal Drexhage experiment we probe the LDOS of a nanomechanically approached mirror. Due to the electrodynamic interaction of the antenna with its own mirror image the superemitter traces the inverse LDOS of the mirror, in stark contrast to a bare source, whose decay rate is proportional to the mirror LDOS.

  14. ``Excess'' polarization of the spontaneous emission in laser heterostructures

    Science.gov (United States)

    Ptashchenko, A. A.; Ptashchenko, F. A.

    1996-10-01

    "Excess" polarization of the spontaneous emission (EPSE) of diode lasers at low injection levels, being more pronounced in degraded specimens, has been observed. A model of EPSE is proposed, involving tunnel radiative recombination of electrons and light holes at inhomogeneities of the p- n junction. Separating EPSE from the polarization effect caused by elastic deformation enables the strain in the active region of laser heterostructures to be determined.

  15. Spontaneous emission enhancement in metal–dielectric metamaterials

    International Nuclear Information System (INIS)

    We study the spontaneous emission of a dipole emitter imbedded into a layered metal–dielectric metamaterial. We demonstrate ultra-high values of the Purcell factor in such structures due to a high density of states with hyperbolic isofrequency surfaces. We reveal that the traditional effective-medium approach greatly underestimates the value of the Purcell factor due to the presence of an effective nonlocality, and we present an analytical model which agrees well with numerical calculations.

  16. Spectrum in spontaneous emission: Beyond the Weisskopf-Wigner approximation

    International Nuclear Information System (INIS)

    The theory of spontaneous emission presented by Weisskopf and Wigner [V. Weisskopf and E. Wigner, Z. Phys. 63, 54 (1930)] provides an excellent approximation of the actual decay that atoms undergo on optically allowed transitions. However, the theory cannot be rigorously correct since it leads to a Lorentzian spectrum that extends to negative frequencies. Within the rotating-wave approximation, we derive a closed-form expression for the spectrum that is valid for all frequencies.

  17. Spontaneous emission enhancement in metal-dielectric metamaterials

    CERN Document Server

    Iorsh, Ivan; Orlov, Alexey; Belov, Pavel; Kivshar, Yuri

    2011-01-01

    We study the spontaneous emission of a dipole emitter imbedded into a layered metal-dielectric metamaterial. We demonstrate ultra-high values of the Purcell factor in such structures due to a high density of states with hyperbolic isofrequency surfaces. We reveal that the traditional effective-medium approach greatly underestimates the value of the Purcell factor due to the presence of an effective nonlocality, and we present an analytical model which agrees well with numerical calculations.

  18. General Theory of Spontaneous Emission Near Exceptional Points

    OpenAIRE

    Pick, Adi; Zhen, Bo; Miller, Owen D.; Hsu, Chia W.; Hernandez, Felipe; Rodriguez, Alejandro W.; Soljacic, Marin; Johnson, Steven G

    2016-01-01

    Exceptional points (EPs)---non-Hermitian degeneracies where both the eigenvalues and the eigenvectors coalesce---have recently been realized in various optical systems. Here we present a general theory of spontaneous emission near such degeneracies, where standard mode-expansion methods lead to erroneous divergent results. We show that significant (and finite) enhancements for light-matter interaction can occur in systems with gain, whereas in passive systems the enhancement is at most four-f...

  19. General Theory of Spontaneous Emission Near Exceptional Points

    CERN Document Server

    Pick, Adi; Miller, Owen D; Hsu, Chia W; Hernandez, Felipe; Rodriguez, Alejandro W; Soljacic, Marin; Johnson, Steven G

    2016-01-01

    Exceptional points (EPs)---non-Hermitian degeneracies where both the eigenvalues and the eigenvectors coalesce---have recently been realized in various optical systems. Here we present a general theory of spontaneous emission near such degeneracies, where standard mode-expansion methods lead to erroneous divergent results. We show that significant (and finite) enhancements for light-matter interaction can occur in systems with gain, whereas in passive systems the enhancement is at most four-fold. Under special conditions, the emission spectral lineshape near the EP becomes a squared Lorentzian, and the enhancement scales quadratically with the resonance lifetime.

  20. Calculation of the output power in self-amplified spontaneous radiation using scaling of power with number of simulation particles

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.H. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    1998-10-01

    Recent advances in self-amplified spontaneous emission (SASE) experiments stimulate interest in quantitative comparison of measurements with theory. In this paper we show that the widely used simulation code TDA3D, developed by Tran and Wurtele [Comput. Phys. Commun. {bold 54}, 263 (1989)] even though a single frequency code, can be used to determine the output power in the SASE process with excellent approximation in the exponential growth regime. The method applies when the gain is not very high, which is a special advantage, because when the gain is not very high, the analytical calculation is particularly difficult since the exponential growing term does not dominate. The analysis utilizes a scaling relation between the output power and the number of simulation particles in the code TDA3D: {l_angle}P{r_angle}=N{sub {lambda}}{sup {prime}}/N{sub {lambda}}{l_angle}P{sup {prime}}{r_angle}, where {l_angle}P{r_angle} is the output power and N{sub {lambda}} is the line density of the electrons, while {l_angle}P{sup {prime}}{r_angle} is the calculated output power using a line density N{sub {lambda}}{sup {prime}} of the number of simulation particles in the code TDA3D. Because of the scaling property, the number of simulation particles can be taken to be many orders of magnitude less than the actual experiment. Comparison of our results with experiment yields new insight into the SASE process. {copyright} {ital 1998} {ital The American Physical Society}

  1. Controlling spontaneous emission of light by photonic crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2005-01-01

    Photonic bandgap crystals were proposed almost two decades ago as a unique tool for controlling propagation and emission of light. Since then the research field of photonic crystals has exploded and many beautiful demonstrations of the use of photonic crystals and fibers for molding light...... propagation have appeared that hold great promises for integrated optics. These major achievements solidly demonstrate the ability to control propagation of light. In contrast, an experimental demonstration of the use of photonic crystals for timing the emission of light has so far lacked. In a recent...... publication in Nature, we have demonstrated experimentally that both the direction and time of spontaneous emission can be controlled, thereby confirming the original proposal by Eli Yablonovich that founded the field of photonic crystals. We believe that this work opens new opportunities for solid...

  2. Coherent control of spontaneous emission near a photonic band edge

    International Nuclear Information System (INIS)

    We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band gap (PBG) material, with one resonant frequency near the edge of the PBG. Spontaneous emission from the three-level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free-space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This non-zero steady-state population is achieved by virtue of the localization of light in the vicinity of the emitting atom. It is robust to decoherence effects provided that the Rabi frequency of the control laser field exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase-sensitive optical memory device on the atomic scale. The protected electric dipole within the PBG provides a basis for a qubit to encode information for quantum computations. A detailed literature survey on the nature, fabrication and applications of PBG materials is presented to provide context for this research. (phd tutorial)

  3. Spontaneous emission spectra from a staggered-array undulator

    International Nuclear Information System (INIS)

    A staggered-array undulator set inside the superconducting solenoid coils is shown to be able to provide high undulator fields larger than the longitudinal magnetic fields, a small undulator period, easy tunability through the solenoid coil current, and compact and easy fabrication. The overall performance characteristics of this undulator were studied mainly with respect to iron and aluminum disk widths, and spontaneous emission spectra through the numerical calculations. The maximum undulator field is found to be obtained for the ratio of the aluminum disk width to the undulator period of 0.45. The line widths (FWHM) of the spontaneous emission spectra, however, do not show Nw-1 dependence on the number of the undulator period Nw for practical beams with a Gaussian distribution, compared with for a single electron. The energy spread among various parameters is seen to play an important role in reducing the FWHM with increase of Nw. The large tunability of the wavelength is proved to cover 6-10 mm by changing the solenoid magnetic field from 0.4 T to 1.6 T. (author)

  4. Spontaneous emission enhancement of colloidal CdSe nanoplatelets

    Science.gov (United States)

    Yang, Zhili; Pelton, Matthew; Waks, Edo

    Colloidal CdS /CdSe/CdS nanoplatelets synthesized recently are high efficient nano-emitters and gain media for nanoscale lasers and other nonlinear optical devices. They are characterized as quantum well structure due to energy gap difference between core CdSe and shell CdS, of which the luminescent wavelength could be tuned precisely by their thickness of growth. However, the influence of environment on the material's optical properties and further enhancement of the emission to implement nanoscale systems remains to be investigated. Here we demonstrate spontaneous emission rate enhancement of these CdSe nanoplatelets coupled to a photonic crystal cavity. We show clearly the photoluminescent spectrum modification of the nanoplatelets emission and an averaged Purcell enhancement factor of 3.1 is achieved when they are coupled to carefully-designed nanobeam photonic crystal cavities compared to the ones on unpatterned surface in our experiment of lifetime measurement. Also the phenomenon of cavity quality factor increasing is observed when increasing intensity of pumping, which attributes to saturable absorption of the nanoplatelets. Our success in enhancement of emission from these nanoplatelets here paves the road to realize actual nanoscale integrated systems such as ultra-low threshold micro-cavity lasers.

  5. Sex and Ear Differences in Spontaneous and Click-Evoked Otoacoustic Emissions in Young Adults

    Science.gov (United States)

    Snihur, Adrian W. K.; Hampson, Elizabeth

    2011-01-01

    Effects of sex and handedness on the production of spontaneous and click-evoked otoacoustic emissions (OAEs) were explored in a non-hearing impaired population (ages 17-25 years). A sex difference in OAEs, either produced spontaneously (spontaneous OAEs or SOAEs) or in response to auditory stimuli (click-evoked OAEs or CEOAEs) has been reported in…

  6. Tunable Casimir-Polder Forces and Spontaneous Emission Rates

    Science.gov (United States)

    Rosa, Felipe; Kort-Kamp, Wilton; Pinheiro, Felipe; Cysne, Tarik; Oliver, Diego; Farina, Carlos

    2015-03-01

    We investigate the dispersive Casimir-Polder interaction between a Rubidium atom and a graphene sheet subjected to an external magnetic field B. We demonstrate that this concrete physical system allows for a high degree of control of dispersive interactions at micro and nanoscales. Indeed, we show that the application of an external magnetic field can induce a 80 % reduction of the Casimir-Polder energy relative to its value without the field. We also show that sharp discontinuities emerge in the Casimir-Polder interaction energy for certain values of the applied magnetic field at low temperatures. In addition, we also show that atomic spontaneous emission rates can be greatly modified by the action of the magnetic field, with an order of magnitude enhancement or suppression depending on the dipole's moment orientation.

  7. Cooperative spontaneous emission from volume sources in layered media

    International Nuclear Information System (INIS)

    The classical theory of radiation from a dipole located inside a microcavity is extended to the case of a volume source placed inside a layered medium. Cooperation phenomena that can take place in the spontaneous emission process are taken into account with an approach based on the theory of spatial coherence. Three cases are considered: noncooperation, long-range cooperation, and short-range cooperation. In all these cases, the expressions found for the out coupled power are analytical. As an application of the theory, an Alq3-based organic light emitting diode is analyzed. The optical properties of the device are evaluated and compared for two different types of cathode, one consisting of an Al layer, the other one consisting of an Al/LiF bi-layer. The results found show that the ultra-thin LiF layer significantly improves extraction efficiency

  8. Spontaneous emission enhancement in micropatterned GaN

    Science.gov (United States)

    Niehus, M.; Sanguino, P.; Monteiro, T.; Soares, M. J.; Schwarz, R.

    2004-10-01

    With two interfering pulses from the fourth harmonic of a Nd-YAG laser we burnt a periodic lattice structure into the surface of GaN thin films. The lattice period of this permanent grating could be controlled between less than one and several tens of microns. Above the decomposition threshold, nitrogen evades from the sample surface, and the residual metallic gallium accumulates in the form of tiny droplets at the surfaces. The patterned structure shows structural similarities with microcavities. The question arises if the residual metallic gallium may act as a partially reflecting mirror. To test this hypothesis, we studied the steady-state and transient photoluminescence through the modulation of light emerging from the ubiquitous broad "yellow" photoluminescence band. The microlattice is evidenced by energy-equidistant spontaneous emission enhancement peaks in the steady-state photoluminescence spectra. We suggest that the partial reflection due to the residual metallic gallium leads to the observed enhancement effect.

  9. DC field induced enhancement and inhibition of spontaneous emission in a cavity

    OpenAIRE

    Agarwal, G. S.; Pathak, P. K.

    2003-01-01

    We demonstrate how spontaneous emission in a cavity can be controlled by the application of a dc field. The method is specially suitable for Rydberg atoms. We present a simple argument for the control of emission.

  10. Spontaneous Emission of an Excited Atom in a Dusty Unmagnetized Plasma Medium

    OpenAIRE

    Naser Alinejad; Noushin Pishbin

    2014-01-01

    Investigation of spontaneous decay of an excited atom in dusty unmagnetized plasma is presented in this paper. The transverse contribution to the decay rate is normally associated with spontaneous emission. The rate of spontaneous emission can be obtained by Fermi’s golden rule. In this calculation, the transverse contribution to dielectric permittivity and Green function technique are used. Calculation of the decay rate of atoms is applicable to understand the particular structure of the vac...

  11. Spontaneous emission and the operation of invisibility cloaks

    Science.gov (United States)

    Morshed Behbahani, Mina; Amooghorban, Ehsan; Mahdifar, Ali

    2016-07-01

    As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous, and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary invisibility cloak on the atomic radiative properties. The time dependence of the atomic subsystem is obtained in the Schrodinger picture. By introducing a modified set of the spherical wave-vector functions, the Green tensor of the system is calculated via exact and discrete methods. In this formalism, the decay rate and as well the emission pattern of the aforementioned atom are computed analytically for both weak and strong coupling interaction, and then numerically calculations are done to demonstrate the performances of cloaking in the quantum mechanics domain. Special attention is paid to different possible orientations and locations of the atomic system near the spherical invisibility cloaking. Results in the presence and the absence of the invisibility cloak are compared. We find that the cloak works very well far from its resonance frequency to conceal a macroscopic object, whereas at near the resonance frequency the object is more visible than the situation where the object is not covered by the cloak.

  12. Broadband enhancement of spontaneous emission in a photonic-plasmonic structure

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Xie, Fengxian; Shi, Lei;

    2012-01-01

    We demonstrate that a broadband enhancement of spontaneous emission can be achieved within a photonic-plasmonic structure. The structure can strongly modify the spontaneous emission by exciting plasmonic modes. Because of the excited plasmonic modes, an enhancement up to 30 times is observed, lea...

  13. Prompt Neutron Emission in 252CF Spontaneous Fission

    Science.gov (United States)

    Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

    2011-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  14. Efficient computation of spontaneous emission dynamics in arbitrary photonic structures

    Science.gov (United States)

    Teimourpour, M. H.; El-Ganainy, R.

    2015-12-01

    Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples.

  15. Efficient computation of spontaneous emission dynamics in arbitrary photonic structures

    International Nuclear Information System (INIS)

    Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples. (paper)

  16. Single Photon Subradiance: Quantum control of spontaneous emission and ultrafast readout

    OpenAIRE

    Scully, Marlan O.

    2015-01-01

    Recent work has shown that collective single photon emission from an ensemble of resonate two-level atoms, i.e. single photon superradiance, is a rich field of study. The present paper addresses the flip side of superradiance, i.e. subradiance. Single photon subradiant states are potentially stable against collective spontaneous emission and can have ultrafast readout. In particular it is shown how many atom collective effects provide a new way to control spontaneous emission by preparing and...

  17. Spatial oscillations in the spontaneous emission rate of an atom inside a metallic wedge

    CERN Document Server

    Zhao, H J

    2010-01-01

    A method of images is applied to study the spontaneous emission of an atom inside a metallic wedge with an opening angle of $\\pi/N$, where N is an arbitrary positive integer. We show the method of images gives a rate formula consistent with that from Quantum Electrodynamics. Using the method of images, we show the correspondence between the oscillations in the spontaneous emission rate and the closed-orbits of emitted photon going away and returning to the atom inside the wedge. The closed-orbits can be readily constructed using the method of images and they are also extracted from the spontaneous emission rate.

  18. Spontaneous emission control of single quantum dots by electromechanical tuning of a photonic crystal cavity

    CERN Document Server

    Midolo, L; Hoang, T B; Xia, T; van Otten, F W M; Li, L H; Linfield, E; Lermer, M; Höfling, S; Fiore, A

    2012-01-01

    We demonstrate the control of the spontaneous emission rate of single InAs quantum dots embedded in a double-membrane photonic crystal cavity by the electromechanical tuning of the cavity resonance. Controlling the separation between the two membranes with an electrostatic field we obtain the real-time spectral alignment of the cavity mode to the excitonic line and we observe an enhancement of the spontaneous emission rate at resonance. The cavity has been tuned over 13 nm without shifting the exciton energies. A spontaneous emission enhancement of 4.5 has been achieved with a coupling efficiency of the dot to the mode 92%.

  19. Nanopillar Arrays on Semiconductor Membranes as Electron Emission Amplifiers

    OpenAIRE

    Qin, Hua; Kim, Hyun-Seok; Blick, Robert H.

    2007-01-01

    A new transmission-type electron multiplier was fabricated from silicon-on-insulator (SOI) material by integrating an array of one dimensional (1D) silicon nanopillars onto a two dimensional (2D) silicon membrane. Primary electrons are injected into the nanopillar-membrane system from the flat surface of the membrane, while electron emission from the other side is probed by an anode. The secondary electron yield (SEY) from nanopillars is found to be about 1.8 times that of plane silicon membr...

  20. To decay or not to decay - or both ! quantum mechanics of spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Lodahl, Peter; Mørk, Jesper

    2008-01-01

    We discuss calculations of spontaneous emission from quantum dots in photonic crystals and show how the decay depends on the intrinsic properties of the emitter as well as the position. A number of fundamentally different types of spontaneous decay dynamics are shown to be possible, including...... counter intuitive situations in which the quantum dot decays only partially....

  1. Quantum control of population inversion in the presence of spontaneous emission

    OpenAIRE

    Schirmer, S. G.; Greentree, Andrew D.; Solomon, A. I.

    2001-01-01

    The detrimental effect of spontaneous emission on the performance of control schemes designed to achieve population inversion between the ground state and a highly excited atomic state are studied using computer simulations.

  2. Observation of broadband self-amplified spontaneous coherent terahertz synchrotron radiation in a storage ring

    International Nuclear Information System (INIS)

    Bursts of coherent synchrotron radiation at far-infrared and millimeter wavelengths have been observed at several storage rings. A microbunching instability has been proposed as the source for the bursts. However,the microbunching mechanism has yet to be elucidated. We provide the first evidence that the bursts are due to a microbunching instability driven by the emission of synchrotron radiation in the bunch. Observations made at the Advanced Light Source are consistent with the values predicted by a model for the microbunching proposed by Heifets and Stupakov. These results demonstrate a new instability regime for high energy synchrotron radiation sources and will impact the design of future sources

  3. Modulation response of quantum dot nanolight-emitting-diodes exploiting purcell-enhanced spontaneous emission

    DEFF Research Database (Denmark)

    Skovgård, Troels Suhr; Gregersen, Niels; Lorke, Michael;

    2011-01-01

    The modulation bandwidth for a quantum dot light-emitting device is calculated using a detailed model for the spontaneous emission including the optical and electronic density-of-states. We show that the Purcell enhancement of the spontaneous emission rate depends critically on the degree of...... inhomogeneous broadening relative to the cavity linewidth and can improve the modulation speed only within certain parameter regimes....

  4. Dynamics of Spontaneous Emission Controlled by Local Density of States in Photonic Crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter; Nikolaev, Ivan S.; van Driel, A. Floris;

    2006-01-01

    We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter.......We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter....

  5. Spontaneous emission control of single quantum dots by electromechanical tuning of a photonic crystal cavity

    OpenAIRE

    Midolo, L.; Pagliano, F.; Hoang, T.B.; Xia, T; van Otten, F. W. M.; Li, L. H.; Linfield, E. H.; Lermer, M.; Höfling, S.; Fiore, A.

    2012-01-01

    We demonstrate the control of the spontaneous emission rate of single InAs quantum dots embedded in a double-membrane photonic crystal cavity by the electromechanical tuning of the cavity resonance. Controlling the separation between the two membranes with an electrostatic field we obtain the real-time spectral alignment of the cavity mode to the excitonic line and we observe an enhancement of the spontaneous emission rate at resonance. The cavity has been tuned over 13 nm without shifting th...

  6. Spontaneous emission control of single quantum dots in bottom-up nanowire waveguides

    OpenAIRE

    Bulgarini, Gabriele; Reimer, Michael E.; Zehender, Tilman; Hocevar, Moïra; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.; Zwiller, Valery

    2012-01-01

    Nanowire waveguides with controlled shape are promising for engineering the collection efficiency of quantum light sources. We investigate the exciton lifetime in individual InAsP quantum dots, perfectly positioned on-axis of InP nanowire waveguides. We demonstrate control over the quantum dot spontaneous emission by varying the nanowire diameter in e-beam patterned arrays, which modifies the coupling efficiency of the emitter to the fundamental waveguide mode. The spontaneous emission rate i...

  7. Spontaneous Emission from a Driven Atom Embedded in a Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    XIE Shuang-Yuan; YANG Ya-Ping; CHENG Hong; ZHU Shi-Yao; WU Xiang

    2000-01-01

    The properties of the spontaneous emission from a three-level atom with an external driving field in a photonic crystal are studied. The population in the two upper levels displays complete decay or oscillatory behavior,depending on the initial atomic state and the relative position of the two upper levels from the forbidden gap.The intensity and the phase of the external field can also affect spontaneous emission from the atom.

  8. A Charge-Sensitive Amplifier Associated with APD or PMT for Positron Emission Tomography Scanners

    OpenAIRE

    Mathez, H; Russo, P.; Lu, G.-N.; Pittet, P.; Quiquerez, L.; Lecoq, J.; Bohner, G.

    2010-01-01

    We present a Charge-Sensitive Amplifier (CSA) to be coupled with a 511-KeV 2-photon detector for positron emission tomography scanners. The circuit has been designed to be associated with an Avalanche Photodiode (APD) or Photo-Multiplier Tube (PMT) with large capacitance. It is a two-stage structure. The input stage consists of a foldedcascode fully-differential part and a common-mode feedback (CMFB) circuit. The output stage employs complementary source followers. The amplifier has been desi...

  9. Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

    DEFF Research Database (Denmark)

    Frimmer, Martin; Chen, Yuntian; Koenderink, A. Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment whi...

  10. Spontaneous emission in two-dimensional photonic crystal microcavities

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2000-01-01

    The properties of the radiation field in a two-dimensional photonic crystal with and without a microcavity introduced are investigated through the concept of the position-dependent photon density of states. The position-dependent rate of spontaneous radiative decay for a two-level atom with random...

  11. STUDY OF THE GAMMA EMISSION PROBABILITY ACCOMPANYING THE SPONTANEOUS FISSION OF CF-252

    NARCIS (Netherlands)

    VANDERPLOEG, H; LAURENS, CR; BACELAR, JCS; BUDA, A; GAARDHOJE, JJ; VANTHOF, G; KALANTARNAYESTANAKI, N; VANDERWOUDE, A; ZELAZNY, Z

    1994-01-01

    A study of the gamma emission accompanying the spontaneous fission process of Cf-252 has been performed. The photon emission probability between 3 and 70 MeV and its angular dependence with respect to the fission direction were measured. These measurements were performed as a function of the mass as

  12. Effects of spontaneous otoacoustic emissions on pure-tone frequency difference limens

    DEFF Research Database (Denmark)

    Hansen, Rói; Santurette, Sébastien; Verhulst, Sarah

    2014-01-01

    Pure-tone frequency difference limens (FDLs) have been shown to vary in the vicinity of spontaneous otoacoustic emissions (SOAEs). As lower FDLs have been observed near SOAEs when measured ipsi- and contralaterally to the emission ear, it has been proposed that prolonged ongoing stimulation of ne...

  13. Spontaneous emission of electromagnetic radiation in turbulent plasmas

    International Nuclear Information System (INIS)

    Known radiation emission mechanisms in plasmas include bremmstrahlung (or free-free emission), gyro- and synchrotron radiation, cyclotron maser, and plasma emission. For unmagnetized plasmas, only bremmstrahlung and plasma emissions are viable. Of these, bremmstrahlung becomes inoperative in the absence of collisions, and the plasma emission requires the presence of electron beam, followed by various scattering and conversion processes. The present Letter proposes a new type of radiation emission process for plasmas in a state of thermodynamic quasi-equilibrium between particles and enhanced Langmuir turbulence. The radiation emission mechanism proposed in the present Letter is not predicted by the linear theory of thermal plasmas, but it relies on nonlinear wave-particle resonance processes. The electromagnetic particle-in-cell numerical simulation supports the new mechanism

  14. Modeling and Simulations of Electron Emission from Diamond-Amplified Cathodes

    International Nuclear Information System (INIS)

    Emission of electrons from a diamond-amplified cathode was recently demonstrated. This experiment was based on a promising new concept for generation of high-current, high-brightness, and low thermal emittance electron beams. The measurements from transmission and emission experiments have shown the potential to realize the diamond-amplified cathode concept. However, the results indicate that the involved physical properties should be understood in greater detail to build diamond cathodes with optical properties. We have already made progress in understanding the secondary electron generation and charge transport in diamond with the models we implemented in the VORPAL computational framework. We have been implementing models for electron emission from diamond and will present results from 3D VORPAL simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, propagation of the charge clouds, and then the emission of electrons into diamond. We will discuss simulation results on the dependence of the electron emission on diamond surface properties.

  15. Study of amplified emission in polycrystalline ZnO below characteristic temperature

    CERN Document Server

    Tiwari, Sanjiv Kumar

    2012-01-01

    We report on amplified emission in polycrystalline ZnO below 100K. At 6K emission is due to free exciton FXn=1 A (3.378 eV), bound exciton D1XA (3.347 eV), donor acceptor pair DAP (3.275 eV) and longitudinal phonon replica of free excitons (FXn=1 A -mLO, m= 1,2,3) respectively. Peak intensity of D1XA and FXn=1 A -1LO transition increases non-linearly with increase of excitation intensity due to exciton-exciton scattering. Peak position of D1XA shows red shift while FXn=1 A -1LO shows blue shift with increase of excitation intensity. Fraction of exciton taking part in emission process and radiative lifetime of exciton decreases with decrease of temperature .Threshold value of excitation for D1XA decreases exponentially with decrease of temperature upto 100K. Whereas, below 100K no functional behaviour is observed. Threshold for FXn=1A-1LO emission was observed up to 75K, at higher temperature it is mixed with D1XA. Time delayed photoluminescence measurement reveals that amplified emission decay faster than spo...

  16. Effects of salicylates and aminoglycosides on spontaneous otoacoustic emissions in the Tokay gecko

    OpenAIRE

    Stewart, Charles E; Hudspeth, A. James

    2000-01-01

    The high sensitivity and sharp frequency discrimination of hearing depend on mechanical amplification in the cochlea. To explore the basis of this active process, we examined the pharmacological sensitivity of spontaneous otoacoustic emissions (SOAEs) in a lizard, the Tokay gecko. In a quiet environment, each ear produced a complex but stable pattern of emissions. These SOAEs were reversibly modulated by drugs that affect mammalian otoacoustic emissions, the salicylates and the aminoglycoside...

  17. Scanning emitter lifetime imaging microscopy for spontaneous emission control

    CERN Document Server

    Frimmer, Martin; Koenderink, A Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nano-photonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while measuring its lifetime. We demonstrate the method by imaging the enhancement of the local density of optical states around metal nanowires. By nano-positioning, the decay rate of a pointlike source of fluorescence can be reversibly and repeatedly changed by a factor of two by coupling it to the guided plasmonic mode of the wire.

  18. Atomic spatial coherence with spontaneous emission in a strong coupling cavity

    CERN Document Server

    Fang, Zhen; Zhou, Xiaoji; Chen, Xuzong

    2010-01-01

    The role of spontaneous emission in the interaction between a two-level atom and a pumped micro-cavity in the strong coupling regime is discussed in this paper. Especially, using a quantum Monte-Carlo simulation, we investigate atomic spatial coherence. It is found that atomic spontaneous emission destroys the coherence between neighboring lattice sites, while the cavity decay does not. Furthermore, our computation of the spatial coherence function shows that the in-site locality is little affected by the cavity decay, but greatly depends on the cavity pump amplitude.

  19. Phase control of spontaneous emission from a double-band photonic crystals

    International Nuclear Information System (INIS)

    Through the picture of dressed states, this paper investigates the spontaneous emission spectrum from a microwave-driven three-level atom embedded in double-band photonic crystals. The physical dynamics of the phase dependent phenomenon are analysed by comparing two models 'upper level coupling' and 'lower level coupling'. When the phase is changed from 0 to π, the variety of spontaneous emission spectra from either of the two models are inverse to each other, in which the relative height and width of the peaks are determined by the density of states in photonic crystals. (classical areas of phenomenology)

  20. Subradiant spontaneous undulator emission through collective suppression of shot noise

    Science.gov (United States)

    Ratner, D.; Hemsing, E.; Gover, A.; Marinelli, A.; Nause, A.

    2015-05-01

    The phenomenon of Dicke's subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting "quiet" beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulator radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.

  1. Highly enhanced spontaneous emission with nanoshell-based metallodielectric hybrid antennas

    Science.gov (United States)

    Cheng, Yuqing; Lu, Guowei; shen, Hongming; Wang, Yuwei; He, Yingbo; Chou, R. Yuanying; Gong, Qihuang

    2015-09-01

    The metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance spontaneous emission greatly rather than the individual spherical nanoparticle. Moreover, the performances of the hybrid antenna can be boosted further through using asymmetrical nanoshell. The mechanism of the high enhancement effect is due to the hybrid structure being able to couple efficiently with the electric field by a larger dipolar moment. And the emission directivity of the hybrid antenna is able to be modified by adjusting the geometry of the plasmonic nanostructures. The results should be beneficial for various fundamental and applied research fields, including single molecule fluorescence and surface enhance Raman spectroscopy, etc. The enhancement of spontaneous emission is in demand in fundamental interests and various applied research fields. However, the electromagnetic enhancement of single plasmonic nanostructure is limited due to intrinsic loss of metal materials and quantum tunneling effect which also limits the ability of enhancement of spontaneous emission. Interestingly, it was found that hybrid structures can provide higher enhancement effect. This study is about a kind new type of optical antenna to control spontaneous emission of single emitter, i.e. a metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate which can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance

  2. Plasmonic phase-gradient metasurface for spontaneous emission control

    Science.gov (United States)

    Langguth, L.; Schokker, A. H.; Guo, K.; Koenderink, A. F.

    2015-11-01

    We combine the concept of phase-gradient metasurfaces with fluorescence directionality control of an ensemble of incoherent emitters. We design a periodic metasurface to control the scattering amplitude of the lattice in momentum space. The lattice is embedded in a waveguiding layer doped with organic fluorophores. In contrast to the usual symmetric directionality that plasmonic lattices impart on emission, we find that the phase gradient translates into asymmetric directional emission into the far field, determined by scattering on a subset of the reciprocal lattice vectors. The measured asymmetry is well explained by analytical modeling.

  3. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures

    CERN Document Server

    Filter, Robert; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-01-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

  4. Large spontaneous-emission enhancements in metallic nanostructures: towards LEDs faster than lasers.

    Science.gov (United States)

    Tsakmakidis, Kosmas L; Boyd, Robert W; Yablonovitch, Eli; Zhang, Xiang

    2016-08-01

    Recent progress in the design and realization of optical antennas enclosing fluorescent materials has demonstrated large spontaneous-emission enhancements and, simultaneously, high radiation efficiencies. We discuss here that an important objective of such work is to increase spontaneous-emission rates to such a degree that light-emitting diodes (LEDs) can possess modulation speeds exceeding those of typical semiconductor lasers, which are usually in the range ~20-50 GHz. We outline the underlying physics that enable large spontaneous-emission enhancements in metallic nanostructures, and we then discuss recent theoretical and experimentally promising results, where enhancements larger than a factor of ~300 have been reported, with radiation efficiencies exceeding 50%. We provide key comparative advantages of these structures in comparison to conventional dielectric microcavity designs, namely the fact that the enhancement of spontaneous emission can be relatively nonresonant (i.e., broadband) and that the antenna nanostructures can be spectrally and structurally compatible for integration with a wide class of emitters, including organic dyes, diamond nanocrystals and colloidal quantum dots. Finally, we point out that physical insight into the underlying effects can be gained by analyzing these metallic nanostructures in their equivalent-circuit (or nano-antenna) model, showing that all main effects (including the Purcell factor) can adequately be described in that approach. PMID:27505759

  5. Modulation response of nanoLEDs and nanolasers exploiting Purcell enhanced spontaneous emission

    DEFF Research Database (Denmark)

    Skovgård, Troels Suhr; Gregersen, Niels; Yvind, Kresten;

    2010-01-01

    The modulation bandwidth of quantum well nanoLED and nanolaser devices is calculated from the laser rate equations using a detailed model for the Purcell enhanced spontaneous emission. It is found that the Purcell enhancement saturates when the cavity quality-factor is increased, which limits the...

  6. Linearly Polarized, Single-Mode Spontaneous Emission in a Photonic Nanowire

    DEFF Research Database (Denmark)

    Munsch, Mathieu; Claudon, Julien; Bleuse, Joël;

    2012-01-01

    We introduce dielectric elliptical photonic nanowires to funnel efficiently the spontaneous emission of an embedded emitter into a single optical mode. Inside a wire with a moderate lateral aspect ratio, the electromagnetic environment is largely dominated by a single guided mode, with a linear...

  7. Measurements and Studies of Secondary Electron Emission of Diamond Amplified Photocathode

    Energy Technology Data Exchange (ETDEWEB)

    Wu,Q.

    2008-10-01

    The Diamond Amplified Photocathode (DAP) is a novel approach to generating electrons. By following the primary electron beam, which is generated by traditional electron sources, with an amplifier, the electron beam available to the eventual application is increased by 1 to 2 orders of magnitude in current. Diamond has a very wide band gap of 5.47eV which allows for a good negative electron affinity with simple hydrogenation, diamond can hold more than 2000MV/m field before breakdown. Diamond also provides the best rigidity among all materials. These two characters offer the capability of applying high voltage across very thin diamond film to achieve high SEY and desired emission phase. The diamond amplifier also is capable of handling a large heat load by conduction and sub-nanosecond pulse input. The preparation of the diamond amplifier includes thinning and polishing, cleaning with acid etching, metallization, and hydrogenation. The best mechanical polishing available can provide high purity single crystal diamond films with no less than 100 {micro}m thickness and <15 nm Ra surface roughness. The ideal thickness for 700MHz beam is {approx}30 {micro}m, which requires further thinning with RIE or laser ablation. RIE can achieve atomic layer removal precision and roughness eventually, but the time consumption for this procedure is very significant. Laser ablation proved that with <266nm ps laser beam, the ablation process on the diamond can easily achieve removing a few microns per hour from the surface and <100nm roughness. For amplifier application, laser ablation is an adequate and efficient process to make ultra thin diamond wafers following mechanical polishing. Hydrogenation will terminate the diamond surface with monolayer of hydrogen, and form NEA so that secondary electrons in the conduction band can escape into the vacuum. The method is using hydrogen cracker to strike hydrogen atoms onto the bare diamond surface to form H-C bonds. Two independent

  8. Spontaneous Muon Emission during Fission, a New Nuclear Radioactivity

    OpenAIRE

    Ion, D. B.; Ion, M. L. D.; Ion-Mihai, Reveica

    2011-01-01

    In this paper the essential theoretical predictions for the nuclear muonic radioactivity are presented by using a special fission-like model similar with that used in description of the pionic emission during fission. Hence, a fission-like model for the muonic radioactivity takes into account the essential degree of freedom of the system: muon-fissility, muon-fission barrier height, etc. Using this model it was shown that most of the SHE-nuclei lie in the region where the muonic fissility par...

  9. Influence of local field on spontaneous light emission by nanoparticles

    DEFF Research Database (Denmark)

    Keller, Ole; Lozovski, V.; Iezhokin, I.

    2009-01-01

    A self-consistent approach based on the local-field concept has been proposed to calculate the direction patterns of light emission by nanoparticles with various shapes. The main idea of the method consists in constructing self-consistent equations for the electromagnetic field at any point of the...... demonstrated to interact as almost point dipoles at distances that exceed their linear dimensions. This fact can be used to substantiate applications of the dipole approximation to studying the optical properties of submonolayer molecular coatings....

  10. Spontaneous emission in the presence of a realistically sized cylindrical waveguide

    Science.gov (United States)

    Dung, Ho Trung

    2016-02-01

    Various quantities characterizing the spontaneous emission process of a dipole emitter including the emission rate and the emission pattern can be expressed in terms of the Green tensor of the surrounding environment. By expanding the Green tensor around some analytically known background one as a Born series, and truncating it under appropriate conditions, complicated boundaries can be tackled with ease. However, when the emitter is embedded in the medium, even the calculation of the first-order term in the Born series is problematic because of the presence of a singularity. We show how to eliminate this singularity for a medium of arbitrary size and shape by expanding around the bulk medium rather than vacuum. In the highly symmetric configuration of an emitter located on the axis of a realistically sized cylinder, it is shown that the singularity can be removed by changing the integral variables and then the order of integration. Using both methods, we investigate the spontaneous emission rate of an initially excited two-level dipole emitter, embedded in a realistically sized cylinder, which can be a common optical fiber in the long-length limit and a disk in the short-length limit. The spatial distribution of the emitted light is calculated using the Born-expansion approach, and local-field corrections to the spontaneous emission rate are briefly discussed.

  11. X-ray spontaneous emission control by 1-dimensional photonic bandgap structure

    OpenAIRE

    André, Jean-Michel; Jonnard, Philippe

    2010-01-01

    Paper available at http://epjd.edpsciences.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/epjd/abs/2010/06/d09549/d09549.html International audience The possibility of controlling the X-ray spontaneous emission of atoms embedded in a 1-dimensional photonic bandgap structure by the so-called Purcell effect, is studied. Calculations of the spontaneously emitted power are presented from Fermi's golden rule in the framework of the Wigner-time approach extended to ...

  12. Proposal for an Enhanced Self-Amplified Spontaneous Emission X-ray Free Electron Laser

    International Nuclear Information System (INIS)

    We describe a technique by which an energy modulation of electrons via interaction with a laser pulse in a wiggler magnet is used for a significant increase of the electron peak current prior to entering a long SASE FEL undulator. This results in a reduction of the gain length for the SASE process and a modification of the structure of the output x-ray radiation. It also temporally links the output x-ray pulse to the initial laser pulse, thus providing an opportunity for accurate synchronization between the laser pump pulse and x-ray probe pulse for pump-probe experiments

  13. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    Science.gov (United States)

    Hackel, Lloyd A.; Soules, Thomas F.; Fochs, Scott N.; Rotter, Mark D.; Letts, Stephan A.

    2008-12-09

    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  14. Fast Capillary Discharge-Enviroment for Amplified Spontaneous Emission in Soft X-ray Region

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Prukner, Václav; Štraus, Jaroslav; Boháček, Vladislav; Frolov, Oleksandr; Vrba, Pavel

    Aachen : International Society of Pulsed Power Applications e.V, 2004, s. 19-23. ISBN 3-8322-3217-6. [European Pulsed Power Symposium/2nd./. DESY, Hamburg (DE), 20.09.2004-23.09.2004] R&D Projects: GA ČR GA202/03/0711; GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z2043910 Keywords : pulse high current capillary discharge Subject RIV: BL - Plasma and Gas Discharge Physics

  15. A second order model of noise in saturated semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Öhman, Filip; Tromborg, Bjarne; Mørk, Jesper

    2005-01-01

    We have developed a second order model of spontaneous emission noise in semiconductor optical amplifiers (SOAs). The resulting noise distributions agree well with statistical simulations and explain the measured redistribution of noise in saturated SOAs.......We have developed a second order model of spontaneous emission noise in semiconductor optical amplifiers (SOAs). The resulting noise distributions agree well with statistical simulations and explain the measured redistribution of noise in saturated SOAs....

  16. Spontaneous otoacoustic emissions in the European edible frog (Rana esculenta): spectral details and temperature dependence.

    Science.gov (United States)

    van Dijk, P; Wit, H P; Segenhout, J M

    1989-11-01

    Spontaneous otoacoustic emissions were recorded in 41 ears of 29 European edible frogs (Rana esculenta). Emission frequencies ranged from 450 to 1350 Hz. The distribution of frequencies shows two distinct populations: one above and one below 1 kHz. With one exception, a maximum number of two emissions were recorded per ear, each in a different population. An amplitude distribution of a frog emission was sampled, from which it was concluded that the emission is generated by an active oscillator. The spectral width of an emission ranged from 1 to 200 Hz (average 38 Hz). There was negative correlation between sound pressure level of an emission and spectral width. In 4 frogs the dependence of emission power and frequency on temperature was investigated. An emission could be 'switched on and off' within a few degrees centigrade. At temperatures below the switching interval no emission was recorded; for higher temperatures emission power showed no dependence on temperature. Frequency increased with temperature (Q10 = 1.1 to 1.3). This yields a mismatch with temperature dependence of best frequencies of auditory fibers. The consequences of this mismatch are discussed. PMID:2691473

  17. Controlling spontaneous emission rates of quantum dots with plasmonic nanopatch antennas

    Science.gov (United States)

    Hoang, Thang; Akselrod, Gleb; Argyropoulos, Christos; Huang, Jiani; Smith, David; Mikkelsen, Maiken

    2015-03-01

    The radiative processes associated with quantum emitters can be strongly enhanced due to intense electromagnetic fields created by plasmonic nanostructures. Here, we experimentally demonstrate large enhancements of the spontaneous emission rate of colloidal quantum dots coupled to single plasmonic nanopatch antennas. The antennas consist of silver nanocubes (75 nm) coupled to a gold film separated by a thin polyelectrolyte spacer layer (~1 nm) and core-shell CdSe/ZnS quantum dots (~6 nm). By optimizing the size of the nanopatch antenna, the plasmonic mode is tuned to be on resonance with the quantum dot emission. We show an increase in the spontaneous emission rate by a factor of 880 (Purcell factor) and a 2300-fold enhancement in the total fluorescence while maintaining a high radiative quantum efficiency of ~50 %. The nanopatch antenna, as demonstrated here, offers highly directional and broadband radiation that can be tailored for emitters from the visible to the near infrared, providing a promising approach for the spontaneous emission control of single quantum emitters.

  18. Cavity-enhanced spontaneous emission rates for rhodamine 6-G in levitated microdroplets

    International Nuclear Information System (INIS)

    Fluorescence decay kinetics of Rhodamine 6-G molecules in levitated glycerol microdroplets (4--20 microns in diameter) have been investigated to determine the effects of spherical cavity resonances on spontaneous emission rates. For droplet diameters greater than 10 microns, the fluorescence lifetime is essentially the same as in bulk glycerol. As the droplet diameter is decreased below 10 microns, bi-exponential decay behavior is observed with a slow component whose rate is similar to bulk glycerol, and a fast component whose rate is as much as a factor of 10 larger than the bulk decay rate. This fast component is attributed to cavity enhancement of the spontaneous emission rate and, within the weak coupling approximation, a value for the homogeneous linewidth at room temperature can be estimated from the fluorescence lifetime data

  19. Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber

    Science.gov (United States)

    Scheel, Stefan; Buhmann, Stefan Yoshi; Clausen, Christoph; Schneeweiss, Philipp

    2015-10-01

    We study the spontaneous emission of an excited atom close to an optical nanofiber and the resulting scattering forces. For a suitably chosen orientation of the atomic dipole, the spontaneous emission pattern becomes asymmetric and a resonant Casimir-Polder force parallel to the fiber axis arises. For a simple model case, we show that such a lateral force is due to the interaction of the circularly oscillating atomic dipole moment with its image inside the material. With the Casimir-Polder energy being constant in the lateral direction, the predicted lateral force does not derive from a potential in the usual way. Our results have implications for optical force measurements on a substrate as well as for laser cooling of atoms in nanophotonic traps.

  20. Control of spontaneous emission from a microwave-field-driven four-level atom in an anisotropic photonic crystal

    International Nuclear Information System (INIS)

    The spontaneous emission properties of a microwave-field-driven four-level atom embedded in anisotropic double-band photonic crystals (PCs) are investigated. We discuss the influences of the band-edge positions, Rabi frequency and detuning of the microwave field on the emission spectrum. It is found that several interesting features such as spectral-line enhancement, spectral-line suppression, spectral-line overlap, and multi-peak structures can be observed in the spectra. The proposed scheme can be achieved by use of a microwave-coupled field into hyperfine levels in rubidium atom confined in a photonic crystal. These theoretical investigations may provide more degrees of freedom to manipulate the atomic spontaneous emission. -- Highlights: ► Spontaneous emission properties of an atom embedded in PCs are investigated. ► Spectral-line enhancement, suppression and overlapping are observed. ► The results provide more degrees of freedom to control atomic spontaneous emission.

  1. Spontaneous emission control of quantum dots embedded in photonic crystals: Effects of external fields and dimension

    Science.gov (United States)

    Vaseghi, B.; Hashemi, H.

    2016-06-01

    In this paper simultaneous effects of external electric and magnetic fields and quantum confinement on the radiation properties of spherical quantum dot embedded in a photonic crystal are investigated. Under the influence of photonic band-gap, effects of external static fields and dot dimension on the amplitude and spectrum of different radiation fields emitted by the quantum dot are studied. Our results show the considerable effects of external fields and quantum confinement on the spontaneous emission of the system.

  2. Investigation of coherent molecular resonances in quantum dot–metallic nanoparticle systems using their spontaneous emission

    International Nuclear Information System (INIS)

    In the presence of metallic nanoparticles the nature of the optical excitations (pumping) of semiconductor quantum dots can be determined by their molecular states and resonances formed via coherent coupling of excitons and plasmons. We show that the spontaneous emission of such quantum dots can provide key information regarding formation and characteristics of such molecular properties. This includes an ultra-fast switching process associated with optical transition between the molecular states of the quantum dot-metallic nanoparticle system or its plasmonic meta-resonance when the intensity of the laser field responsible for the exciton–plasmon coupling reaches a critical value. We also show that by varying the intensity of this laser, the spontaneous emission exhibits characteristic features indicating tunability of the molecular resonances and excitation-power dependence of plasmonic fields of the metallic nanoparticles. - Highlights: • Investigation of collective molecular properties of quantum dot-metallic nanoparticle systems. • Impact of such collective properties on the optical excitation of quantum dots. • Effects of exciton–plasmon coupling in the spontaneous emission of the quantum dots. • Signatures of plasmonic meta-resonances in the fluorescence of quantum dots

  3. Effects of salicylates and aminoglycosides on spontaneous otoacoustic emissions in the Tokay gecko.

    Science.gov (United States)

    Stewart, C E; Hudspeth, A J

    2000-01-01

    The high sensitivity and sharp frequency discrimination of hearing depend on mechanical amplification in the cochlea. To explore the basis of this active process, we examined the pharmacological sensitivity of spontaneous otoacoustic emissions (SOAEs) in a lizard, the Tokay gecko. In a quiet environment, each ear produced a complex but stable pattern of emissions. These SOAEs were reversibly modulated by drugs that affect mammalian otoacoustic emissions, the salicylates and the aminoglycoside antibiotics. The effect of a single i.p. injection of sodium salicylate depended on the initial power of the emissions: ears with strong control SOAEs displayed suppression at all frequencies, whereas those with weak control emissions showed enhancement. Repeated oral administration of acetylsalicylic acid reduced all emissions. Single i.p. doses of gentamicin or kanamycin suppressed SOAEs below 2.6 kHz, while modulating those above 2.6 kHz in either of two ways. For ears whose emission power at 2.6-5.2 kHz encompassed more than half of the total, individual emissions displayed facilitation as great as 35-fold. For the remaining ears, emissions dropped to as little as one-sixth of their initial values. The similarity of the responses of reptilian and mammalian cochleas to pharmacological intervention provides further evidence for a common mechanism of cochlear amplification. PMID:10618439

  4. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS

    International Nuclear Information System (INIS)

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department

  5. Observation of modulated spontaneous emission of Rhodamine 6G in low refractive index contrast 1D-periodic gelatin film

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The modulation of the spontaneous emission of Rhodamine 6G has been observed in one-dimensional periodic dielectric structure of dichromated gelatin film with refractive index contrast as low as 0.01. The spontaneous emission is enhanced at the band edges and inhibits in the band gap, which agree well with the theoretical analysis on the redistribution of the fractional local density of optical states.

  6. Spontaneous emission spectrum of a three-level atom embedded in photonic crystal

    Institute of Scientific and Technical Information of China (English)

    刘国强; 王健; 张汉壮

    2005-01-01

    The two models of three-level (one upper level and two lower levels, or two upper levels and one lower level) atom embedded in a double-band photonic crystal are adopted. The atomic transitions from the upper levels to the lower levels are assumed to be coupled by the same reservoir which are respectively the isotropic photonic band gap (PBG)modes, the anisotropic PBG modes and the free vacuum modes. The effects of the fine structure of the atomic ground state levels in the model with one upper level and two lower levels, and the quantum interferences in the model with two upper levels and one lower level on the spontaneous emission spectrum of an atom are investigated in detail. Most interestingly, it is shown that new spontaneous emission lines are produced from the fine splitting of atomic ground state levels in the isotropic PBG case. The quantum interferences induce additional narrow spontaneous lines near the transition from the empty upper level to the lower level.

  7. Spontaneous coherent microwave emission and the sawtooth instability in a compact storage ring

    Science.gov (United States)

    Arp, U.; Fraser, G. T.; Hight Walker, A. R.; Lucatorto, T. B.; Lehmann, K. K.; Harkay, K.; Sereno, N.; Kim, K.-J.

    2001-05-01

    Strong evidence for self-excited emission of coherent synchrotron radiation in the microwave spectral region was observed at the Synchrotron Ultraviolet Radiation Facility (SURF III) electron storage ring at the NIST. The microwave emission between 25 and 35 mm was dominated by intense bursts of radiation. The intensity enhancement during these bursts was on the order of 10 000 to 50 000 over the incoherent value. The shape, width, and period of the bursts depend strongly on the operational parameters of the storage ring. Coherent microwave emission was observed only when the beam was unstable, namely, during bunch-length relaxation oscillations. We report on the measurements of the microwave bursts, and correlate the data with signals from a beam monitor electrode and photodiode detector. The coherent enhancement of the radiation intensity is ascribed to spontaneous self-induced microbunching of the electrons within the bunch.

  8. Effi›cient and broadband spontaneous emission control in fiber-like photonic nanowires

    DEFF Research Database (Denmark)

    Claudon, Julien; Munsch, Mathieu; Bleuse, Joël;

    Funneling a large fraction of the spontaneous emission (SE) of a quantum emitter into a single optical mode is a powerful strategy for improving the brightness of quantum light sources or developing an efficient spin-photon interface. In the solid state, preferential emission into a single...... localized mode has been first achieved taking advantage of the Purcell effect that arises in semiconductor optical microcavities. In the last years, the need to overcome the limited operation bandwidth inherent to a resonant approach has triggered intense research on SE control in waveguide structures...... consider a photonic nanowire made of GaAs (refractive index n=3.5) and surrounded by air (n=1). It features a circular section (diameter d), and contains spectrally isolated single InAs quantum dots (QD) with a free space emission wavelength around 920 nm. The large refractive index contrast between the...

  9. Experimental studies on the impact of ASE noise of single-channel optical amplifiers in central office applications

    Institute of Scientific and Technical Information of China (English)

    zheng zheng(郑铮)

    2004-01-01

    We identified the amplified spontaneous emission-amplified spontaneous emission (ASE-ASE) beat noise from the semiconductor optical amplifier, which has been overlooked in previous studies, as a cause of severe system penalties when it was used to provide single-channel amplification in a dynamic central office environment through experimental studies. Our results pointed out that the ASE-ASE beat noise of the optical amplifier, other than its gain and noise figure, has to be considered to correctly predict its performance in these new applications.

  10. Molecular hot electroluminescence due to strongly enhanced spontaneous emission rates in a plasmonic nanocavity.

    Science.gov (United States)

    Chen, Gong; Li, Xiao-Guang; Zhang, Zhen-Yu; Dong, Zhen-Chao

    2015-02-14

    We have recently demonstrated anomalous relaxationless hot electroluminescence from molecules in the tunnel junction of a scanning tunneling microscope [Dong et al., Nat. Photonics, 2010, 4, 50]. In the present paper, based on physically realistic parameters, we aim to unravel the underlying physical mechanism using a multiscale modeling approach that combines classical generalized Mie theory with the quantum master equation. We find that the nanocavity-plasmon-tuned spontaneous emission rate plays a crucial role in shaping the spectral profile. In particular, on resonance, the radiative decay rate can be enhanced by three-to-five orders of magnitude, which enables the radiative process to occur on the lifetime scale of picoseconds and become competitive to the vibrational relaxation. Such a large Purcell effect opens up new emission channels to generate the hot luminescence that arises directly from higher vibronic levels of the molecular excited state. We also stress that the critical role of resonant plasmonic nanocavities in tunneling electron induced molecular luminescence is to enhance the spontaneous radiative decay through plasmon enhanced vacuum fluctuations rather than to generate an efficient plasmon stimulated emission process. This improved understanding has been partly overlooked in previous studies but is believed to be very important for further developments of molecular plasmonics and optoelectronics. PMID:25565003

  11. Electrical control of spontaneous emission and strong coupling for a single quantum dot

    DEFF Research Database (Denmark)

    Laucht, A.; Hofbauer, F.; Hauke, N.;

    2009-01-01

    from individual dots can be tuned by4 meV relative to the nanocavity mode before the emission quenches due to carrier tunneling escape. This range is much larger than the typical linewidth of the high-Q cavity modes (100μeV) allowing us to explore and contrast regimes where the dots couple to the...... cavity or decay by spontaneous emission into the two-dimensional photonic bandgap. In the weak-coupling regime, we show that the dot spontaneous emission rate can be tuned using a gate voltage, with Purcell factors>7. New information is obtained on the nature of the dot–cavity coupling in the weak...... coupling regime, and electrical control of zerodimensional polaritons is demonstrated for the highest-Q cavities (Q > 12 000). Vacuum Rabi splittings up to 120μeV are observed, larger than the linewidths of either the decoupled exciton ( 6 40μeV) or cavity mode. These observations represent a voltage...

  12. Broadband filters for abatement of spontaneous emission in circuit quantum electrodynamics

    International Nuclear Information System (INIS)

    The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous emission. Here, we use impedance engineering to design a filter by which photons may easily leave the resonator at the cavity frequency but not at the qubit frequency. We implement this broadband filter in both an on-chip and off-chip configuration

  13. Teleporting the one-qubit state via two-level atoms with spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Hu Mingliang, E-mail: mingliang0301@xupt.edu.cn, E-mail: mingliang0301@163.com [School of Science, Xi' an University of Posts and Telecommunications, Xi' an 710061 (China)

    2011-05-14

    We study quantum teleportation via two two-level atoms coupled collectively to a multimode vacuum field and prepared initially in different atomic states. We concentrated on the influence of the spontaneous emission, collective damping and dipole-dipole interaction of the atoms on fidelity dynamics of quantum teleportation and obtained the region of spatial distance between the two atoms over which the state can be teleported nonclassically. Moreover, we showed through concrete examples that entanglement of the channel state is the prerequisite but not the only essential quantity for predicting the teleportation fidelity.

  14. Studies on a one-dimensional model for the spontaneous emission in the semiclassical approximation

    International Nuclear Information System (INIS)

    Some generalization are made on the spontaneous emission by a plane of excited atoms, described by two level atom-model, in the Δ1=1, Δm=1, transition and using the semiclassical radiation approximation -both discussed in the text. Initially, the radiation rate of an infinite plane of excited atoms is investigated, using Δ1=0, Δm=0, transition. It is shown that we can observe a limit solution depending on the coupling between field and matter. (author)

  15. Local field corrections to the spontaneous emission in arrays of Si nanocrystals

    CERN Document Server

    Poddubny, Alexander N

    2014-01-01

    We present a theory of the local field corrections to the spontaneous emission rate for the array of silicon nanocrystals in silicon dioxide. An analytical result for the Purcell factor is obtained. We demonstrate that the local-field corrections are sensitive to the volume fill factor of the nanocrystals in the sample and are suppressed for large values of the fill factor. The local-field corrections and the photonic density of states are shown to be described by two different effective permittivities: the harmonic mean between the nanocrystal and the matrix permittivities and the Maxwell-Garnett permittivity.

  16. Trace element emissions from spontaneous combustion of gob piles in coal mines, Shanxi, China

    Science.gov (United States)

    Zhao, Y.; Zhang, Jiahua; Chou, C.-L.; Li, Y.; Wang, Z.; Ge, Y.; Zheng, C.

    2008-01-01

    The emissions of potentially hazardous trace elements from spontaneous combustion of gob piles from coal mining in Shanxi Province, China, have been studied. More than ninety samples of solid waste from gob piles in Shanxi were collected and the contents of twenty potentially hazardous trace elements (Be, F, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Hg, Tl, Pb, Th, and U) in these samples were determined. Trace element contents in solid waste samples showed wide ranges. As compared with the upper continental crust, the solid waste samples are significantly enriched in Se (20x) and Tl (12x) and are moderately enriched in F, As, Mo, Sn, Sb, Hg, Th, and U (2-5x). The solid waste samples are depleted in V, Cr, Mn, Co, Ni, Cu, and Zn. The solid waste samples are enriched in F, V, Mn, Cr, Co, Ni, Cu, Zn, Sb, Th, and U as compared with the Shanxi coals. Most trace elements are higher in the clinker than in the unburnt solid waste except F, Sn, and Hg. Trace element abundances are related to the ash content and composition of the samples. The content of F is negatively correlated with the ash content, while Pb is positively correlated with the ash. The concentrations of As, Mn, Zn, and Cd are highly positively correlated with Fe2O3 in the solid waste. The As content increases with increasing sulfur content in the solid waste. The trace element emissions are calculated for mass balance. The emission factors of trace elements during the spontaneous combustion of the gobs are determined and the trace element concentrations in the flue gas from the spontaneous combustion of solid waste are calculated. More than a half of F, Se, Hg and Pb are released to the atmosphere during spontaneous combustion. Some trace element concentrations in flue gas are higher than the national emission standards. Thus, gob piles from coal mining pose a serious environmental problem. ?? 2007 Elsevier B.V. All rights reserved.

  17. Optimizing the spontaneous-emission ß factor for single optical plasmon generation

    DEFF Research Database (Denmark)

    Chen, Yuntian; Nielsen, Torben Roland; Gregersen, Niels; Lodahl, Peter; Mørk, Jesper

    In applications like quantum cryptography and quantum computation, it is desirable to obtain single photon sources which can produce a train of single photons on demand at a high repetition rate, especially at or near room temperature. Such single-photon sources can be realized by tailoring the...... photonic environment of the quantum emitter. The photonic environment determines the local density of states, into which the photon can be emitted. A number of structures such as interfaces, cavities and waveguides have already been used to modify the spontaneous emission (SE) rate; nevertheless there is...

  18. Using a squeezed field to protect two-atom entanglement against spontaneous emissions

    International Nuclear Information System (INIS)

    Tunable interaction between two atoms in a cavity is realized by interacting the two atoms with an extra controllable single-mode squeezed field. Such a controllable interaction can be further used to control entanglement between the two atoms against amplitude damping decoherence caused by spontaneous emissions. For the independent amplitude damping decoherence channel, entanglement will be lost completely without controls, while it can be partially preserved by the proposed strategy. For the collective amplitude damping decoherence channel, our strategy can enhance the entanglement compared with the uncontrolled case when the entanglement of the uncontrolled stationary state is not too large

  19. Extracting Oscillation Frequencies in Spontaneous Emission Rate of an Atom Between Two Mirrors

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hai-Jun; DU Meng-Li

    2007-01-01

    For an atom in a medium with refractive index n sandwiched between two parallel mirrors, we derive an analytical formula for the spontaneous emission rate based on Fermi's golden rule. The oscillations are not transparent in this formula. By performing Fourier transform on scaling variable measuring system size while holding system configuration fixed, we extracted the frequencies of many oscillations in this system. We show that these oscillations correspond to emitted photon closed-orbits going away from and returning to the emitting atom.

  20. Spontaneous emission of a photon: wave packet structures and atom-photon entanglement

    OpenAIRE

    Fedorov, M. V.; Efremov, M. A.; Kazakov, A. E.; Chan, K W; Law, C. K.; Eberly, J. H.

    2004-01-01

    Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem. The atom-photon entanglement arising in such a process is shown to be closely related to the structure of atom ...

  1. Broadband filters for abatement of spontaneous emission in circuit quantum electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bronn, Nicholas T., E-mail: ntbronn@us.ibm.com; Hertzberg, Jared B.; Córcoles, Antonio D.; Gambetta, Jay M.; Chow, Jerry M. [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States); Liu, Yanbing; Houck, Andrew A. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-10-26

    The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous emission. Here, we use impedance engineering to design a filter by which photons may easily leave the resonator at the cavity frequency but not at the qubit frequency. We implement this broadband filter in both an on-chip and off-chip configuration.

  2. Spontaneous emission and collection efficiency enhancement of single emitters in diamond via plasmonic cavities and gratings

    CERN Document Server

    Choy, Jennifer T; Hausmann, Birgit J M; Janitz, Erika; Huang, I-Chun; Lončar, Marko

    2013-01-01

    We demonstrate an approach, based on plasmonic apertures and gratings, to enhance the radiative decay rate of single NV centers in diamond, while simultaneously improving their collection efficiency. Our structures are based on metallic resonators formed by surrounding sub-wavelength diamond nanoposts with a silver film, which can enhance the spontaneous emission rate of an embedded NV center. However, the collection efficiency of emitted photons remains low due to losses to surface plasmons and reflections at the diamond-air interface. In this work, we mitigate photon losses into these channels by incorporating grating structures into the plasmonic cavity system.

  3. Detailed theoretical and experimental investigation of high-gain erbium-doped fiber amplifier

    DEFF Research Database (Denmark)

    Pedersen, Bo; Dybdal, Kristen; Dam-Hansen, Carsten;

    1990-01-01

    A full-scale numerical model for the erbium-doped fiber amplifier has been developed that incorporates realistic index and erbium-concentration profiles as well as the spectral distribution of amplified spontaneous emission (ASE). The high accuracy of the model is demonstrated by comparison with a...

  4. KrF laser amplifier with phase-conjugate Brillouin retroreflectors.

    Science.gov (United States)

    Gower, M C

    1982-09-01

    We have demonstrated the use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers. The mirror was also shown to isolate systems optically from amplifier spontaneous emission. Automatic alignment of targets using this mirror as a retroreflector was also demonstrated. PMID:19714043

  5. Beyond 10 J/2 Hz LUCIA current status with cryogenic amplifier

    International Nuclear Information System (INIS)

    More than 10 Joules at 2 Hz were recently obtained from the LUCIA laser system based on diode-pumped Yb:YAG active mirrors. This achievement is the result of careful management of both Amplified Spontaneous Emission and thermal effects in laser amplifiers. Future developments including a cryogenically-cooled active mirror are also presented. (authors)

  6. Study of a high and low pressure plasma produced in a He-N2 mixture: application to spontaneous emissions by radiative collisions

    International Nuclear Information System (INIS)

    This thesis is centered on the study of the energy transfer from helium metastable atoms to ground state nitrogen molecules by the process of radiative collisions. Experimental techniques employed include the analysis of spontaneous emission from the reaction: He(23S)+N2(X,v=0) → He(11S)+(N2sup(R)(B,v'=4,5) → N2sup(R)(X,v'')+hω), where R indicates highly excited nitrogen Rydberg states. As the lower level Rydberg states are autoionizing, the net effect of the radiative collision is identical that of Penning ionization where the Rydberg to states are intermediates. The results of this study lend support to the validity of a radiative collision based laser amplifier model proposed in the thesis

  7. Exploding wire in water – a potential environment for amplification of spontaneous emission in soft X-ray region below 15 nm

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Prukner, Václav; Frolov, Oleksandr; Štraus, Jaroslav

    Praha: Institute of Plasma Physics AS CR, v.v.i, 2007 - (Schmidt, J.; Šimek, M.; Pekárek, S.; Prukner, V.). s. 98 ISBN 978-80-87026-00-7. [International Conference on Phenomena in Ionized Gases/28th./. 15.07.2007-20.07.2007, Praha] R&D Projects: GA ČR GA202/06/1324; GA MŠk 1P04LA235; GA AV ČR KAN300100702; GA AV ČR KJB100430702 Institutional research plan: CEZ:AV0Z20430508 Keywords : exploding wire in water * amplified spontaneous emission * soft X-ray laser Subject RIV: BL - Plasma and Gas Discharge Physics

  8. Exploding wire in water – a potential environment for amplification of spontaneous emission in soft X-ray region below 15 nm

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Prukner, Václav; Frolov, Oleksandr; Štraus, Jaroslav

    Praha: Institute of Plasma Physics AS CR, v.v.i, 2007 - (Schmidt, J.; Šimek, M.; Pekárek, S.; Prukner, V.), s. 74-77 ISBN 978-80-87026-01-4. [International Conference on Phenomena in Ionized Gases/28th./. Praha (CZ), 15.07.2007-20.07.2007] R&D Projects: GA ČR GA202/06/1324; GA MŠk 1P04LA235; GA AV ČR KAN300100702; GA AV ČR KJB100430702 Institutional research plan: CEZ:AV0Z20430508 Keywords : exploding wire in water * amplified spontaneous emission * soft X-ray laser Subject RIV: BL - Plasma and Gas Discharge Physics

  9. Frequency-dependent spontaneous emission rate from CdSe and CdTe nanocrystals: Influence of dark states

    DEFF Research Database (Denmark)

    van Driel, A. F.; Allan, G.; Delerue, C.;

    2005-01-01

    We studied the rate of spontaneous emission from colloidal CdSe and CdTe nanocrystals at room temperature. The decay rate, obtained from luminescence decay curves, increases with the emission frequency in a supralinear way. This dependence is explained by the thermal occupation of dark exciton...

  10. On the spontaneous emission of electromagnetic radiation in the CSL model

    International Nuclear Information System (INIS)

    Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particle’s state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013). -- Highlights: •We compute the electromagnetic radiation emission in collapse models. •Under only the dipole approximation, the equations of motion are solved exactly. •The electromagnetic interaction must be treated exactly. •In order to obtain the correct emission rate the particle must be bounded

  11. On the spontaneous emission of electromagnetic radiation in the CSL model

    Energy Technology Data Exchange (ETDEWEB)

    Donadi, Sandro, E-mail: sandro.donadi@ts.infn.it [Department of Physics, University of Trieste, Strada Costiera 11, 34151 Trieste (Italy); Istituto Nazionale di Fisica Nucleare, Trieste Section, Via Valerio 2, 34127 Trieste (Italy); Deckert, Dirk-André, E-mail: deckert@math.ucdavis.edu [Department of Mathematics, University of California, One Shields Ave, 95616 Davis (United States); Bassi, Angelo, E-mail: bassi@ts.infn.it [Department of Physics, University of Trieste, Strada Costiera 11, 34151 Trieste (Italy); Istituto Nazionale di Fisica Nucleare, Trieste Section, Via Valerio 2, 34127 Trieste (Italy)

    2014-01-15

    Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particle’s state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013). -- Highlights: •We compute the electromagnetic radiation emission in collapse models. •Under only the dipole approximation, the equations of motion are solved exactly. •The electromagnetic interaction must be treated exactly. •In order to obtain the correct emission rate the particle must be bounded.

  12. On the spontaneous emission of electromagnetic radiation in the CSL model

    Science.gov (United States)

    Donadi, Sandro; Deckert, Dirk-André; Bassi, Angelo

    2014-01-01

    Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particle's state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013).

  13. Epitaxy, phase separation and band-edge emission of spontaneously formed InGaN nanorods

    Science.gov (United States)

    De, Arpan; Shivaprasad, S. M.

    2016-09-01

    An In-flux dependent study of the nature of epitaxy, compositional phase separation and band-edge emission of spontaneously formed c-oriented InGaN nanorods on c-sapphire is performed. At higher In flux-rates, m-faceted thick nanorods (≈700 nm) form with two in-plane epitaxial orientations, and display compositional phases with In composition varying from 14 to 63%. In these rods, photo-luminescent (PL) emission is seen to originate only from the localized high-In phase (63%) that is embedded in the low-In (14%) InGaN matrix. As the In flux-rate is reduced, nanorods of smaller diameter (≈60 nm) and a coalesced nanorod network are formed, with In incorporation of 15% and 9%, respectively. These faceted, c-aligned thinner nanorods are of a single compositional phase and epitaxy and display room-temperature PL emission. Optical absorption and emission properties of these nanostructures follow Vegard’s law of band-gaps, and the observed bowing parameter and Stokes shifts correlate to the observed compositional inhomogeneity and carrier localization.

  14. Temperature enhancement of Xe(L) x-ray amplifier (λ ∼ 2.9 A) emission

    International Nuclear Information System (INIS)

    Cooling of the xenon nozzle flow to T = 230 K produces three leading effects. They are (1) a ∼2.5-fold enhancement of the Xe(L) hollow atom emission on the single-vacancy 3d → 2p charge state arrays (2) the production of amplifying self-trapped plasma channels with significantly enhanced lengths and (3) very sharply augmented emission on (2s-bar2p-bar) Xe(L) double-vacancy transitions in the λ ≅ 2.80 A region. (fast track communication)

  15. Final LDRD report : enhanced spontaneous emission rate in visible III-nitride LEDs using 3D photonic crystal cavities.

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Arthur Joseph; Subramania, Ganapathi S.; Coley, Anthony J.; Lee, Yun-Ju; Li, Qiming; Wang, George T.; Luk, Ting Shan; Koleske, Daniel David; Fullmer, Kristine Wanta

    2009-09-01

    The fundamental spontaneous emission rate for a photon source can be modified by placing the emitter inside a periodic dielectric structure allowing the emission to be dramatically enhanced or suppressed depending on the intended application. We have investigated the relatively unexplored realm of interaction between semiconductor emitters and three dimensional photonic crystals in the visible spectrum. Although this interaction has been investigated at longer wavelengths, very little work has been done in the visible spectrum. During the course of this LDRD, we have fabricated TiO{sub 2} logpile photonic crystal structures with the shortest wavelength band gap ever demonstrated. A variety of different emitters with emission between 365 nm and 700 nm were incorporated into photonic crystal structures. Time-integrated and time-resolved photoluminescence measurements were performed to measure changes to the spontaneous emission rate. Both enhanced and suppressed emission were demonstrated and attributed to changes to the photonic density of states.

  16. Control of spontaneous emission from a microwave-field-coupled three-levelΛ-type atom in photonic crystals

    International Nuclear Information System (INIS)

    The spontaneous emission spectrum of a three-level Λ-type atom driven by a microwave field was studied. For the two transitions coupled to the same modified reservoir, we discussed the influence of photonic band gap and Rabi frequency of the microwave field on the emission spectrum. The emission spectrum is given for different locations of the upper band-edge frequency. With the transition frequencies moving from outside the band gap to inside, the number of peaks decreases in the emission spectrum and the multipeak structure of spectral line is finally replaced by a strong non-Lorentzian shape. With increase of the Rabi frequency of the microwave field, we find the spectral line changes from a multipeak structure to a two-peak structure, originating from the inhibition of spontaneous emission for the corresponding decay channel.

  17. Lifetime distribution of spontaneous emission from an assembly of atoms in a dielectric slab

    International Nuclear Information System (INIS)

    Spontaneous decay behavior from an assembly of atoms (or molecules) in a dielectric slab sandwiched by two dielectric semi-infinite spaces with arbitrary refractive indices is investigated. We introduce a lifetime distribution function to describe decay kinetics. The zero-point fluctuations of the electromagnetic field are calculated as a function of the position of atom in the slab. They display a symmetric profile with respect to the central plane of the slab in symmetric structure sample and the contributions of the guided modes and the radiation modes components both exhibit cosinelike variation with a base but with a phase difference of π. With the increase of the thickness of the slab, the oscillations become dense. In contrast, for the asymmetric structure case, the related curves are asymmetric with respect to the middle plane of slab and exhibit considerably distorted cosinelike oscillations. The dependence of the spontaneous emission rate of atoms on the thickness of the slab and the refractive indices of substrate also is surveyed. Our calculations show that quite wide or narrow lifetime distribution can occur for different thicknesses of the slab. The coexistence of both accelerated and inhibited decay processes appears. The calculated results are in good agreement with experimental results

  18. Decay of stimulated and spontaneous emission in highly excited homoepitaxial GaN

    International Nuclear Information System (INIS)

    The high-density effects in the recombination of electron - hole plasma in photoexcited homoepitaxial GaN epilayers were studied by means of transient photoluminescence at room temperature. Owing to the 'backward' and 'lateral' photoluminescence measurement geometries employed, the influence of stimulated transitions on the decay of degenerate nonthermalized plasma was revealed. The lateral stimulated emission was demonstrated to cause a remarkable increase in the recombination rate on the early stage of the luminescence transient. A delayed enhancement of the stimulated emission due to the cooling of plasma from the initial temperature of 1100 K was observed. After completion of the thermalization process and exhaustion of the stimulated emission, the spontaneous-luminescence decay exhibited an exponential slope that relates to the nonradiative recombination of the carriers. The homoepitaxially grown GaN layer featured a luminescence decay time of 445 ps that implies a room-temperature free-carrier lifetime of 890 ps (considered to be extremely high for undoped hexagonal GaN). [copyright] 2001 American Institute of Physics

  19. Decay of stimulated and spontaneous emission in highly excited homoepitaxial GaN

    Energy Technology Data Exchange (ETDEWEB)

    Jursenas, S.; Kurilcik, N.; Kurilcik, G.; Zukauskas, A.; Prystawko, P.; Leszcynski, M.; Suski, T.; Perlin, P.; Grzegory, I.; Porowski, S.

    2001-06-11

    The high-density effects in the recombination of electron{endash}hole plasma in photoexcited homoepitaxial GaN epilayers were studied by means of transient photoluminescence at room temperature. Owing to the {open_quotes}backward{close_quotes} and {open_quotes}lateral{close_quotes} photoluminescence measurement geometries employed, the influence of stimulated transitions on the decay of degenerate nonthermalized plasma was revealed. The lateral stimulated emission was demonstrated to cause a remarkable increase in the recombination rate on the early stage of the luminescence transient. A delayed enhancement of the stimulated emission due to the cooling of plasma from the initial temperature of 1100 K was observed. After completion of the thermalization process and exhaustion of the stimulated emission, the spontaneous-luminescence decay exhibited an exponential slope that relates to the nonradiative recombination of the carriers. The homoepitaxially grown GaN layer featured a luminescence decay time of 445 ps that implies a room-temperature free-carrier lifetime of 890 ps (considered to be extremely high for undoped hexagonal GaN). {copyright} 2001 American Institute of Physics.

  20. New nuclear decay modes by spontaneous and beta-enhanced emission of heavy ions

    International Nuclear Information System (INIS)

    The analytical variant of the superasymmetric fussion model (ASAFM) is improved to include shell effects in the zero point vibration energy. In this way better agreement with experimental half-lives for 380 β emitters, 14C radioactivity of 222Ra and the spontaneous fission of uranium isotopes is obtained. The lifetimes of trans-lead nuclides in the range 1010-1030s are estimated for more than 150 emitted heavy ions with atomic numbers smaller than 25. The shell structure and the oddeven effects are cleary manifested in these new decay modes. One way to enhance the emission rates for these processes is to use α-decaying precursors populating excited levels from which quantum mechanical tunneling goes faster. (authors)

  1. Spontaneous hot-electron light emission from electron-fed optical antennas

    CERN Document Server

    Buret, Mickael; Dellinger, Jean; Cazier, Nicolas; Mennemanteuil, Marie-Maxime; Berthelot, Johann; Smetanin, Igor V; Protsenko, Igor E; Colas-des-Francs, Gérard; Bouhelier, Alexandre

    2015-01-01

    Nanoscale electronics and photonics are among the most promising research areas providing functional nano-components for data transfer and signal processing. By adopting metal-based optical antennas as a disruptive technological vehicle, we demonstrate that these two device-generating technologies can be interfaced to create an electronically-driven self-emitting unit. This nanoscale plasmonic transmitter operates by injecting electrons in a contacted tunneling antenna feedgap. Under certain operating conditions, we show that the antenna enters a highly nonlinear regime in which the energy of the emitted photons exceeds the quantum limit imposed by the applied bias. We propose a model based upon the spontaneous emission of hot electrons that correctly reproduces the experimental findings. The electron-fed optical antennas described here are critical devices for interfacing electrons and photons, enabling thus the development of optical transceivers for on-chip wireless broadcasting of information at the nanos...

  2. Suppression of spontaneous emission and superradiance over macroscopic distances in media with negative refraction

    International Nuclear Information System (INIS)

    The possibility of negative optical path length in left-handed media (LHM) is shown to lead to complete suppression of spontaneous emission of an atom in front of a mirror with a layer of LHM. For the same reason two atoms put at the foci of a perfect lens formed by a parallel LHM slab [J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] exhibit perfect subradiance and superradiance. It is shown that these effects occur over distances that can be orders of magnitude larger than the transition wavelength and are only limited by the propagation length within the free-space decay time of the atoms. Single- and two-atom decay rates are calculated from the Greens function of the electric field in the presence of a LHM and limitations as well as potential applications are discussed

  3. Modal theory of modified spontaneous emission for a hybrid plasmonic photonic-crystal cavity system

    CERN Document Server

    Dezfouli, Mohsen Kamandar; Hughes, Stephen

    2016-01-01

    We present an analytical modal description of the rich physics involved in hybrid plasmonic-photonic devices that is confirmed by full dipole solutions of Maxwell's equations. Strong frequency-dependence for the spontaneous emission decay rate of a quantum dipole emitter coupled to these hybrid structures is predicted. In particular, it is shown that the Fano-type resonances reported experimentally in hybrid plasmonic systems, arise from a very large interference between dominant quasinormal modes of the systems in the frequency range of interest. The presented model forms an efficient basis for modelling quantum light-matter interactions in these complex hybrid systems and also enables the quantitativ prediction and understanding of non-radiative coupling losses.

  4. High energy γ emission in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    The prompt γ emission in the spontaneous fission of 252Cf is characterized by an energy spectrum which extends up to 20 MeV. It was established that the spectrum presents in the neighbourhood of symmetric fission an intensity bump in the 3-8 MeV γ energy interval. The origin of this phenomenon is still not well understood, so that it was found interesting to carry out new measurements. The spectrum of the γ rays emitted in spontaneous fission of 252Cf has been measurement in the EUROGAM II multidetector using photovoltaic cells to detect fragments. The aim of the experiment was to investigate the γ yield enhancement which appears for mass fragment ratio near 132/120. This enhancement was found to be composed of two peaks located at 4 MeV and 5.5 MeV respectively. The results obtained confirm the intensity bound in the 3-8 MeV region but this augmentation reaches the maximum when the heavy fragment is near the mass 132. Beyond mass 140 the phenomenon diminish and the γ spectrum regains the behaviour expected for a statistic emission. The additional structure at 5.5 MeV does not vary with excitation energy while the excitation function of the 4 MeV structure is more structured and presents a maximum when the excitation energy is near 8 MeV. It is likely that all or part of this observed phenomenon is due to a particular excitation mode of this isotope associated for instance with a low energy dipole resonance. A theoretical study of this collective effect is under way

  5. Gravity Wave Emission by Spontaneous Imbalance of Baroclinic Waves in the Continuously Stratified Rotating Annulus

    Science.gov (United States)

    Borchert, Sebastian; Achatz, Ulrich; Rieper, Felix; Fruman, Mark

    2013-04-01

    We use a numerical model of the classic differentially heated rotating annulus experiment to study the spontaneous emission of gravity waves (GWs) from jet stream imbalances, which is a major source of these waves in the atmosphere for which no satisfactory parameterization exists. Atmospheric observations are the main tool for the testing and verification of theoretical concepts but have their limitations. Given their specific potential for yielding reproducible data and for studying process dependence on external system parameters, laboratory experiments are an invaluable complementary tool. Experiments with a rotating annulus exhibiting a jet modulated by large-scale waves due to baroclinic instability have already been used to study GWs: Williams et al (2008) observed spontaneously emitted interfacial GWs in a two-layer flow, and Jacoby et al (2011) detected GWs emitted from boundary-layer instabilities in a differentially heated rotating annulus. Employing a finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate the GWs in a wide and shallow annulus with relatively large temperature difference between inner and outer cylinder walls. In this atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, various analyses suggest a distinct gravity wave activity. To identify regions of GW emission we decompose the flow into the geostrophic and ageostrophic part through the inversion of the quasi-geostrophic potential vorticity (e.g. Verkley, 2009). The analysis of the geostrophic sources of the ageostrophic flow indicates that, in addition to boundary layer instabilities, spontaneous imbalance in the jet region acts as an important source mechanism. Jacoby, T. N. L., Read, P. L., Williams, P. D. and Young, R. M. B., 2011: Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability. Geophys

  6. Influence of uniaxial compression on the mechanism and polarization of spontaneous THz emission from p-Ge

    International Nuclear Information System (INIS)

    Dependence of the intensity of polarized spontaneous emission on a uniaxial compression in p-Ge is investigated. It is shown that, with increase of the stress, the plot of the emission intensity against the direction of polarization ort suffers a phase deviation by π/2. The phenomenon is explained by the alteration of the energy spectrum of free and impurity states under the uniaxial compression

  7. Finite-element modeling of spontaneous emission of a quantum emitter at nanoscale proximity to plasmonic waveguides

    DEFF Research Database (Denmark)

    Chen, Yuntian; Nielsen, Torben Roland; Gregersen, Niels;

    2010-01-01

    We develop a self-consistent finite-element method to quantitatively study spontaneous emission from emitters in nanoscale proximity of plasmonic waveguides. In the model, it is assumed that only one guided mode is dominatingly excited by the quantum emitter, while the cross section of the...

  8. Spontaneous emission inhibition of telecom-band quantum disks inside single nanowire on different substrates

    CERN Document Server

    Birowosuto, M D; Yokoo, A; Takiguchi, M; Notomi, M

    2014-01-01

    We investigate the inhibited spontaneous emission of telecom-band InAs quantum disks (Qdisks) in InP nanowires (NWs). We have evaluated how the inhibition is affected by different disk diameter and thickness. We also compared the inhibition in standing InP NWs and those NWs laying on silica (SiO2), and silicon (Si) substrates. We found that the inhibition is altered when we put the NW on the high-refractive index materials of Si. Experimentally, the inhibition factor $\\zeta$ of the Qdisk emission at 1,500 nm decreases from 4.6 to 2.5 for NW on SiO2 and Si substrates, respectively. Those inhibitions are even much smaller than that of 6.4 of the standing NW. The inhibition factors well agree with those calculated from the coupling of the Qdisk to the fundamental guided mode and the continuum of radiative modes. Our observation can be useful for the integration of the NW as light sources in the photonic nanodevices.

  9. Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes

    Science.gov (United States)

    Sarpkaya, Ibrahim; Zhang, Zhengyi; Walden-Newman, William; Wang, Xuesi; Hone, James; Wong, Chee W.; Strauf, Stefan

    2013-07-01

    The bright exciton emission of carbon nanotubes is appealing for optoelectronic devices and fundamental studies of light-matter interaction in one-dimensional nanostructures. However, to date, the photophysics of excitons in carbon nanotubes is largely affected by extrinsic effects. Here we perform time-resolved photoluminescence measurements over 14 orders of magnitude for ultra-clean carbon nanotubes bridging an air gap over pillar posts. Our measurements demonstrate a new regime of intrinsic exciton photophysics with prolonged spontaneous emission times up to T1=18 ns, about two orders of magnitude better than prior measurements and in agreement with values hypothesized by theorists about a decade ago. Furthermore, we establish for the first time exciton decoherence times of individual nanotubes in the time domain and find fourfold prolonged values up to T2=2.1 ps compared with ensemble measurements. These first observations motivate new discussions about the magnitude of the intrinsic dephasing mechanism while the prolonged exciton dynamics is promising for applications.

  10. Fabrication and characterization of plasmonic nanocone antennas for strong spontaneous emission enhancement

    Science.gov (United States)

    Hoffmann, Björn; Vassant, Simon; Chen, Xue-Wen; Götzinger, Stephan; Sandoghdar, Vahid; Christiansen, Silke

    2015-10-01

    Plasmonic antennas are attractive nanostructures for a large variety of studies ranging from fundamental aspects of light-matter interactions at the nanoscale to industry-relevant applications such as ultrasensitive sensing, enhanced absorption in solar cells or solar fuel generation. A particularly interesting feature of these antennas is that they can enhance the fluorescence properties of emitters. Theoretical calculations have shown that nanocone antennas provide ideal results, but a high degree of manufacturing precision and control is needed to reach optimal performance. In this study, we report on the fabrication of nanocones with base diameters and heights in the range of 100 nm with variable aspect ratios using focused ion beam milling of sputtered nano-crystalline gold layers. The controlled fabrication process allows us to obtain cones with tailored plasmon resonances. The measured plasmon spectra show very good agreement with finite-difference time-domain calculations. Theoretical investigations predict that these nanocones can enhance the spontaneous emission rate of a quantum emitter by several hundred times while keeping its quantum efficiency above 60%.

  11. Spontaneous emission dynamics in an omnidirectional waveguide made of photonic crystals

    Science.gov (United States)

    Huang, Chih-Hsien; Cheng, Szu-Cheng; Wu, Jing-Nuo; Hsieh, Wen-Feng

    2011-06-01

    The spontaneous emission dynamics of atoms embedded in an omnidirectional waveguide (ODWG), a novel optical waveguide, is studied on the basis of the complete reflection of one-dimensional photonic crystals. With the dispersion curve of the single waveguide mode within the photonic band gap and various extents of background dissipation, we characterize the photon-atom interaction in the ODWG. The photon emitter of the system is a two-level atom embedded in the low-index medium of the multilayer-film ODWG or the atom-ODWG system. Fractional calculus, an innovative mathematical method in optical systems, is applied to solve the equation of motion for this atom-ODWG system. Two kinds of states with different group velocities exhibit totally distinctive dynamical behavior. The high frequency waveguide mode with a fast group velocity shows fast exponential decay in propagation while the band-edge mode with a slow group velocity displays non-Markovian dynamics with non-exponential oscillating time evolution. We therefore suggest different functions of this atom-ODWG system for these two kinds of states. The richness of the physical content of the system is also revealed through investigating the dynamical behavior of the band-edge mode. These results aid in further application and fundamental understanding of the atom-ODWG system.

  12. Endogenous spontaneous ultraweak photon emission in the formation of eye-specific retinogeniculate projections before birth.

    Science.gov (United States)

    Bókkon, István; Scholkmann, Felix; Salari, Vahid; Császár, Noémi; Kapócs, Gábor

    2016-06-01

    In 1963, it was suggested [Sperry, R.W. (1963). Chemoaffinity in the orderly growth of nerve fiber patterns and connections. Proc. Natl. Acad. Sci. USA 50, 703-710.] that molecular cues can direct the development of orderly connections between the eye and the brain (the "chemoaffinity hypothesis"). In the same year, the amazing degree of functional accuracy of the visual pathway in the absence of any external light/photon perception prior to birth [Wiesel, T.N and Hubel, D.H. (1963). Single-cell responses in striate cortex of kittens deprived of vision in one eye. J. Neurophysiol. 26, 1003-1017.] was discovered. These recognitions revealed that the wiring of the visual system relies on innate cues. However, how the eye-specific retinogeniculate pathway can be developed before birth without any visual experience is still an unresolved issue. In the present paper, we suggest that Müller cells (functioning as optical fibers), Müller cell cone (i.e. the inner half of the foveola that is created of an inverted cone-shaped zone of Müller cells), discrete retinal noise of rods, and intrinsically photosensitive retinal ganglion cells might have key functions by means of retinal spontaneous ultraweak photon emission in the development of eye-specific retinogeniculate pathways prior to birth. PMID:26656799

  13. Statistical quantification of 24-hour and monthly variabilities of spontaneous otoacoustic emission frequency in humans.

    Science.gov (United States)

    Haggerty, H S; Lusted, H S; Morton, S C

    1993-10-01

    Previous evidence has suggested a relationship between spontaneous otoacoustic emissions (SOAEs) and established, biological cycles, although detailed statistical quantifications of the suggested relationships do not exist in the literature. In an attempt to statistically quantify the purported circadian and monthly influences on this phenomenon, two experiments were undertaken. The first experiment was conducted over eight weeks, investigating 31 SOAEs recorded from eight women and two men. Time series statistical analysis examined whether daily, weekly, and/or monthly cycles characterized SOAE frequency variability. Results yielded a significant monthly cycle for the majority of SOAEs recorded from the women but for none of the SOAEs recorded from the men. These results suggest the possibility that SOAE frequency fluctuation in women may be entrained to the monthly menstrual cycle. In the second experiment, hourly SOAE frequency stability was examined over a 24-h period to ascertain the nature of the daily frequency variation as precisely as possible. Four SOAEs from two subjects were examined, and time series analysis of these data included (1) modelling the autocorrelation structure of the measurements, (2) resolving each 24-h series of measurements into cyclical components of various periodicities, and (3) testing the statistical significance of given cycles within the spectrum of each series. Findings included a significant 24-h variability of frequency for each SOAE, suggesting the possibility of a circadian influence on frequency fluctuation. Results from the two experiments provide quantitative evidence supporting a hypothetical relationship between SOAEs and established, biological cycles. PMID:8276731

  14. Calculation of spontaneous emission from a V-type three-level atom in photonic crystals using fractional calculus

    International Nuclear Information System (INIS)

    Fractional time derivative, an abstract mathematical operator of fractional calculus, is used to describe the real optical system of a V-type three-level atom embedded in a photonic crystal. A fractional kinetic equation governing the dynamics of the spontaneous emission from this optical system is obtained as a fractional Langevin equation. Solving this fractional kinetic equation by fractional calculus leads to the analytical solutions expressed in terms of fractional exponential functions. The accuracy of the obtained solutions is verified through reducing the system into the special cases whose results are consistent with the experimental observation. With accurate physical results and avoiding the complex integration for solving this optical system, we propose fractional calculus with fractional time derivative as a better mathematical method to study spontaneous emission dynamics from the optical system with non-Markovian dynamics.

  15. Modification of spontaneous emission rate of micrometer-sized light sources using hollow-core photonic crystal fibers

    Institute of Scientific and Technical Information of China (English)

    Lu Jiao-Hua; Meng Zi-Ming; Liu Hai-Ying; Feng Tian-Hua; Dai Qiao-Feng; Wu Li-Jun; Gun Qi; Hu Wei; Lan Sheng

    2009-01-01

    We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometer. sized light sources embedded in a hollow-core photonic crystal fiber(HCPCF). The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by canillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.

  16. Cooling molecular vibrations with shaped laser pulses: optimal control theory exploiting the timescale separation between coherent excitation and spontaneous emission

    International Nuclear Information System (INIS)

    Laser cooling of molecules employing broadband optical pumping involves a timescale separation between laser excitation and spontaneous emission. Here, we optimize the optical pumping step using shaped laser pulses. We derive two optimization functionals to drive population into those excited state levels that have the largest spontaneous emission rates to the target state. We show that, when using optimal control, laser cooling of molecules works even if the Franck–Condon map governing the transitions is preferential to heating rather than cooling. Our optimization functional is also applicable to the laser cooling of other degrees of freedom provided the cooling cycle consists of coherent excitation and dissipative de-excitation steps whose timescales are separated. (paper)

  17. Amplification of supercontinuum by semiconductor and Er-doped fiber optical amplifiers

    International Nuclear Information System (INIS)

    We demonstrated selective amplification of supercontinuum ultrashort optical pulses around 1300-nm and 1550-nm bands by injecting a supercontinuum source into a semiconductor optical amplifier (SOA) and an erbium-doped fiber amplifier (EDFA), respectively. The broadband supercontinuum source was obtained by coupling femtosecond Ti:Sapphire laser pulses into a dual zero-dispersion wavelengths nonlinear photonic crystal fiber. The amplified supercontinuum has fully utilized the gain bandwidth of SOA and EDFA. However, the CW background amplified spontaneous emission increases as a result of the reflection at fiber ends to cause noisy pulse train

  18. Spontaneous emission and the operation of invisibility cloaks: Can the invisibility cloaks render objects invisible in quantum mechanic domain?

    OpenAIRE

    Behbahani, Mina Morshed; Amooghorban, Ehsan; Mahdifar, Ali

    2016-01-01

    As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary in...

  19. Correspondence Between Oscillations and Emitted Photon Closed-Orbits in Spontaneous Emission Rate of an Atom Near a Dielectric Slab

    International Nuclear Information System (INIS)

    We study the oscillations in the spontaneous emission rate of an atom near a dielectric slab. The emission rate is calculated as a function of system size using quantum electrodynamics. It exhibits multi-periodic oscillations. Four frequencies of the oscillations are extracted by Fourier transforms. They agree with actions of photon closed-orbits going away and returning to the atom. These oscillations are explained as manifestations of quantum interference effects between the emitted photon wave near the atom and the returning photon waves travelling along various closed-orbits.

  20. Spontaneous Emission Enhancement from polymer-embedded colloidal PbS Nanocrystals into Si-based photonics at telecom wavelengths

    CERN Document Server

    Humer, Markus; Jantsch, Wolfgang; Fromherz, Thomas

    2013-01-01

    We experimentally demonstrate the coupling of optically excited PbS nanocrystal (NC) photoluminescence (PL) into Si-based ring resonators and waveguides at 300K. The PbS NCs are dissolved into Novolak polymer at various concentrations and applied by drop-casting. The coupling mechanism and the spontaneous emission enhancement are experimentally investigated and compared to theoretical predictions. Quality (Q) factors of 2500 were obtained in emission and transmission for wavelengths centered around 1.45{\\mu}m. PL intensity shows a linear dependence on the excitation power and no degradation of the Q factors. Devices with stable optical properties are obtained by this versatile technique.

  1. Correspondence Between Oscillations and Emitted Photon Closed-Orbits in Spontaneous Emission Rate of an Atom Near a Dielectric Slab

    Institute of Scientific and Technical Information of China (English)

    YUN Su-Jun; WANG Fu-He; ZHOU Yun-Song; DU Meng-Li

    2007-01-01

    We study the oscillations in the spontaneous emission rate of an atom near a dielectric slab. The emission rate is calculated as a function of system size using quantum electrodynamics. It exhibits multi-periodic oscillations.Four frequencies of the oscillations are extracted by Fourier transforms. They agree with actions of photon closed-orbits going away and returning to the atom. These oscillations are explained as manifestations of quantum interference effects between the emitted photon wave near the atom and the returning photon waves travelling along various closed-orbits.

  2. Ytterbium-doped large-mode-area photonic crystal fiber amplifier with gain shaping for use at long wavelengths

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas T.; Poli, Federica; Coscelli, Enrico; Jørgensen, Mette Marie; Laurila, Marko; Lægsgaard, Jesper; Broeng, Jes

    2012-01-01

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with efficient suppression of amplified spontaneous emission is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes...... define the large-mode-area core. Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and distributed spectral filtering of amplified spontaneous. The fiber properties give control of the gain shape and are ideal for amplification in the long...

  3. Design of fiber coupled Er3+: Chalcogenide microsphere amplifier via particle swarm optimization algorithm

    OpenAIRE

    Palma, Giuseppe; Bia, Pietro; Mescia, Luciano; Yano, Tetsuji; Nazabal, Virginie; Taguchi, Jun; Moréac, Alain; Prudenzano, Francesco

    2013-01-01

    A mid-IR amplifier consisting of a tapered chalcogenide fiber coupled to an Er3+-doped chalcogenide microsphere has been optimized via a particle swarm optimization (PSO) approach. More precisely, a dedicated three-dimensional numerical model, based on the coupled mode theory and solving the rate equations, has been integrated with the PSO procedure. The rate equations have included the main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important...

  4. Modeling of Mid-IR Amplifier Based on an Erbium-Doped Chalcogenide Microsphere

    OpenAIRE

    P. Bia; Di Tommaso, A; De Sario, M.

    2012-01-01

    An optical amplifier based on a tapered fiber and an Er3+-doped chalcogenide microsphere is designed and optimized. A dedicated 3D numerical model, which exploits the coupled mode theory and the rate equations, is used. The main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions have been considered. Both the pump and signal beams are efficiently injected and obtained by a suitable...

  5. Spontaneous emission intensity and anisotropy of quantum dot films in proximity to nanoscale photonic–plasmonic templates

    Science.gov (United States)

    Indukuri, Chaitanya; Basu, J. K.

    2016-07-01

    We discuss results on spontaneous emission intensity and lifetime anisotropy of cadmium selenide quantum dot monolayer films placed in close proximity to a porous block copolymer based photonic–plasmonic two dimensional array. The porous block copolymer cylinders can be filled with metal nanoparticles and the concentration of these nanoparticles is varied to control both the photoluminescence intensity and lifetime of a layer of quantum dots placed above the template. Significant emission enhancement is achieved even for the quantum dot layer whose core lies about 1 nm above the template surface. Interestingly, polarised decay lifetime analysis indicates considerable emission anisotropy, as well for these quantum dots. Our results thus demonstrates how such hybrid optical materials can be created with controlled optical properties and suggests extension of this method to other novel two dimensional materials in combination with the photonic–plasmonic template.

  6. Design of a thin disk amplifier with extraction during pumping for high peak and average power Ti:Sa systems (EDP-TD).

    Science.gov (United States)

    Chvykov, Vladimir; Nagymihaly, Roland S; Cao, Huabao; Kalashnikov, Mikhail; Osvay, Karoly

    2016-02-22

    Combination of the scheme of extraction during pumping (EDP) and the Thin Disk (TD) technology is presented to overcome the limitations associated with thermal cooling of crystal and transverse amplified spontaneous emission in high average power laser systems based on Ti:Sa amplifiers. The optimized design of high repetition rate 1-10 PW Ti:Sapphire EDP-TD power amplifiers are discussed, including their thermal dynamic behavior. PMID:26907029

  7. CO2 emission of coal spontaneous combustion and its relation with coal microstructure, China.

    Science.gov (United States)

    Wang, Haiyan; Chen Chen; Huang, Tao; Gao, Wei

    2015-07-01

    Coal spontaneous combustion is widely distributed all over the world. CO2 is the main greenhouse gas emitted by coal spontaneous combustion. In the present study characters of CO2 emitted by 10 typical Chinese coal spontaneous combustion and the influence of raw coal functional group on CO2 was studied. CO2 already exists under normal temperature as coal exposed in atmosphere. Under low temperature, the quality of CO2 released by coal spontaneous combustion is relatively small, but tends to increase. And corresponding with it, the oxygen consumption amount is also small. At medium temperature, the oxygen consumption increases rapidly and CO2 mass release rate begins to increase rapidly. Then, CO2 release rate increase rapidly under relatively high temperature (higher than 673 K). Over 873K, concentration of O2 is 6% and release rate of CO2 tends to be steady. It also concluded that mass ratio of CO to CO2 (CO/CO2) during coal spontaneous combustion was lowerthan 0.10 at low temperature. And then, it increased rapidly at medium temperature and reached to top at about 673 K. At 673-873 K, the ratio decreased again, and did not decrease evidently at about 873K. At temperature higher than 873K, the ratio was about 0.13. During the whole testing temperature range, CO/CO2 was not be higher than 0.26, lower than 0.2. This means that release rate of CO2 was much higher than CO during the whole process of coal spontaneous combustion. Moreover, the gas release quantity of CO2 is positively related with carbony content in raw coal. Carbonyl and carboxyl were both material basis of CO2. PMID:26364484

  8. Model based prediction of the existence of the spontaneous cochlear microphonic

    Science.gov (United States)

    Ayat, Mohammad; Teal, Paul D.

    2015-12-01

    In the mammalian cochlea, self-sustaining oscillation of the basilar membrane in the cochlea can cause vibration of the ear drum, and produce spontaneous narrow-band air pressure fluctuations in the ear canal. These spontaneous fluctuations are known as spontaneous otoacoustic emissions. Small perturbations in feedback gain of the cochlear amplifier have been proposed to be the generation source of self-sustaining oscillations of the basilar membrane. We hypothesise that the self-sustaining oscillation resulting from small perturbations in feedback gain produce spontaneous potentials in the cochlea. We demonstrate that according to the results of the model, a measurable spontaneous cochlear microphonic must exist in the human cochlea. The existence of this signal has not yet been reported. However, this spontaneous electrical signal could play an important role in auditory research. Successful or unsuccessful recording of this signal will indicate whether previous hypotheses about the generation source of spontaneous otoacoustic emissions are valid or should be amended. In addition according to the proposed model spontaneous cochlear microphonic is basically an electrical analogue of spontaneous otoacoustic emissions. In certain experiments, spontaneous cochlear microphonic may be more easily detected near its generation site with proper electrical instrumentation than is spontaneous otoacoustic emission.

  9. High-precision three-dimensional atom localization via spontaneous emission in a four-level atomic system

    Science.gov (United States)

    Wang, Zhiping; Yu, Benli

    2016-06-01

    We investigate the three-dimensional atom localization via spontaneous emission in a four-level atomic system. It is found that the detecting probability and precision of atom localization can be significantly improved due to the interference effects induced by the vacuum radiation field and the two laser fields. More importantly, the almost 100% probability of finding an atom within a certain range can be reached when corresponding conditions are satisfied. As a result, our scheme may be helpful in a spatially selective single-qubit phase gate, entangling gates, and quantum error correction for quantum information processing.

  10. Effect of Quantum Interference from Incoherent Pumping Field and Spontaneous Emission on Controlling the Optical Bistability and Multi-Stability

    Institute of Scientific and Technical Information of China (English)

    H.R.Hamedi; Ali Sari; M.Sahrai; S.H.Asadpour

    2013-01-01

    Optical bistability (OB) and optical multi-stability (OM) of a four-level A-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated.The effect of quantum interference arising from spontaneous emission and incoherent pumping on OB and OM is discussed.It is found that the threshold of OB and OM can be controlled by quantum interference mechanisms.In addition intensity of coupling field and the rate of an incoherent pumping field on behavior of OB and OM are then discussed.

  11. Quantum limited noise figure operation of high gain erbium doped fiber amplifiers

    DEFF Research Database (Denmark)

    Lumholt, Ole; Povlsen, Jørn Hedegaard; Schüsler, Kim;

    1993-01-01

    Performance improvements obtained by using an isolator as an amplified-spontaneous-emission-suppressing component within erbium-doped fibers are evaluated. Simultaneous high-gain and near-quantum-limited noise figures can be obtained by such a scheme. The noise figure improves for input signal po...

  12. Estimate of sulfur, arsenic, mercury, fluorine emissions due to spontaneous combustion of coal gangue: An important part of Chinese emission inventories.

    Science.gov (United States)

    Wang, Shaobin; Luo, Kunli; Wang, Xing; Sun, Yuzhuang

    2016-02-01

    A rough estimate of the annual amount of sulfur, arsenic, mercury and fluoride emission from spontaneous combustion of coal gangue in China was determined. The weighted mean concentrations of S, As, Hg, and F in coal gangue are 1.01%, 7.98, 0.18, and 365.54 mg/kg, respectively. Amounts of S, As, Hg, and F emissions from coal gangue spontaneous combustion show approximately 1.13 Mt, and 246, 45, and 63,298 tons in 2013, respectively. The atmospheric release amount of sulfur from coal gangue is more than one tenth of this from coal combustion, and the amounts of As, Hg, and F are close to or even exceed those from coal combustion. China's coal gangue production growth from 1992 to 2013 show an obvious growth since 2002. It may indicate that Chinese coal gangue has become a potential source of air pollution, which should be included in emission inventories. PMID:26650082

  13. High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm

    OpenAIRE

    Stappel, M.; Steinborn, R.; Kolbe, D.; Walz, J

    2012-01-01

    We present a high power single-frequency ytterbium fiber amplifier system with an output power of 30 W at 1091 nm. The amplifier system consists of two stages, a preamplifier stage in which amplified spontaneous emission is efficiently suppressed (>40 dB) and a high power amplifier with an efficiency of 52 %. Two different approaches of frequency doubling are compared. We achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped periodically poled stoichiometric LiTaO3 and up...

  14. Microwave photonic interference mitigation filter based on semiconductor optical amplifier

    Science.gov (United States)

    Xu, Enming; Zhang, Xinliang; Zhou, Lina; Zhang, Yu; Yu, Yuan; Wang, Fei; Huang, Dexiu

    2009-11-01

    A microwave photonic interference mitigation filter is proposed and experimentally demonstrated. The structure is based on a recirculating delay line loop comprising a semiconductor optical amplifier (SOA) and a tunable narrowband optical filter. Converted signal used as negative tap is generated through wavelength conversion employing cross-gain modulation of amplified spontaneous emission spectrum of the SOA. The converted signal circulating in the RDL loop realizes a high quality factor (Q) response after photo-detection. A bandpass response with negative coefficients combined with a broadband allpass response achieves a notch response with flat passband.

  15. Optically amplified free-space optical communication systems

    OpenAIRE

    Aladeloba, Abisayo Olufemi

    2013-01-01

    This thesis investigates terrestrial atmospheric FSO communication systems operating under the influence of turbulence-induced scintillation, beam spreading, optical interchannel crosstalk, amplified spontaneous emission noise and pointing errors. On-off keying-non–return-to-zero (OOK-NRZ) and digital pulse position (DPPM) are the modulation schemes used for the calculations. The possibility of using sophisticated performance evaluation techniques such as moment generating function (MGF)-...

  16. Spontaneous emission and the operation of invisibility cloaks: Can the invisibility cloaks render objects invisible in quantum mechanic domain?

    CERN Document Server

    Behbahani, Mina Morshed; Mahdifar, Ali

    2016-01-01

    As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary invisibility cloak on the atomic radiative properties. The time dependence of the atomic subsystem is obtained in the Schrodinger picture. By introducing a modified set of the spherical wave vector functions, the Green tensor of the system is calculated via the continuous and discrete methods. In this formalism, the decay rate and as well the emission pattern of the aforementioned atom are computed analytically for both weak and strong coupling interaction, and then numerically calculations are done to demonstrate the perfo...

  17. Finite-time deviations from exponential decay in the Weisskopf-Wigner model of spontaneous emission

    International Nuclear Information System (INIS)

    For the first time to the authors' knowledge, a mathematically rigorous method is used for treating finite-time deviations from the exponential decay in the case of spontaneous Lyman-α transition in a two-level hydrogenic atom. In the so-called Weisskopf-Wigner model (where the rotating-wave approximation is implied), finite-time deviations with a rigorous validity range, based on accurate error estimations, are derived. (orig.)

  18. Using Spontaneous Emission of a Qubit as a Resource for Feedback Control

    Science.gov (United States)

    Campagne-Ibarcq, P.; Jezouin, S.; Cottet, N.; Six, P.; Bretheau, L.; Mallet, F.; Sarlette, A.; Rouchon, P.; Huard, B.

    2016-08-01

    Persistent control of a transmon qubit is performed by a feedback protocol based on continuous heterodyne measurement of its fluorescence. By driving the qubit and cavity with microwave signals whose amplitudes depend linearly on the instantaneous values of the quadratures of the measured fluorescence field, we show that it is possible to stabilize permanently the qubit in any targeted state. Using a Josephson mixer as a phase-preserving amplifier, it was possible to reach a total measurement efficiency η =35 %, leading to a maximum of 59% of excitation and 44% of coherence for the stabilized states. The experiment demonstrates multiple-input multiple-output analog Markovian feedback in the quantum regime.

  19. Spontaneous Ultra-Weak Photon Emission from Human Hands Is Time Dependent

    Directory of Open Access Journals (Sweden)

    R. V. Wijk

    2007-06-01

    Full Text Available Ultra-weak photon emission in the visible range was measured on palm and dorsal side of left and right hand by means of a low noise photomultiplier system. To study the dynamics of this photon emission in a 24 h period photon emission was recorded in 2 h intervals in 5 experiments, utilizing strict protocols for dark adaptation and recording of subjects. Fluctuations in photon emission in the course of 24 h period were demonstrated for each anatomic location. Mean photon emission over the 24 h period differed both between subjects and hand locations. To detect a pattern in the fluctuations the mean value for each location of each subject in each experiment was utilized to calculate fluctuations during the course of 24 h for each anatomical location. The fluctuations in photon emission in the course of 24 h were more at dorsal sides than palm sides. The correlation between fluctuations in palm and dorsal side was not apparent. During the 24 h period a change in left-right symmetry occurred for the dorsal side but not for the palm of the hands. Photon emission at the left dorsal location was high at night, while the right dorsal side emitted most during the day. It is concluded that a daily rhythm in photon emission can be recorded from both the dorsal and palm sides of the hands.

  20. Off-axis multipass amplifier as a large aperture driver stage for fusion lasers.

    Science.gov (United States)

    Murray, J E; Downs, D C; Hunt, J T; Hermes, G L; Warren, W E

    1981-03-01

    A multipass amplifier configuration is described which has potential as a large aperture, high gain driver stage for fusion laser systems. We avoid the present limitations of large aperture switches by using an off-angle geometry that does not require an optical switch. The saturated gain characteristics of this multipass amplifier are optimized numerically. Three potential problems are investigated experimentally, self-lasing, output beam quality, and amplified spontaneous emission output. The results indicate comparable cost for comparable performance to a linear chain, with some operational advantage for the multipass driver stage. PMID:20309212

  1. Pulsed operation of a high average power Yb:YAG thin-disk multipass amplifier.

    Science.gov (United States)

    Schulz, M; Riedel, R; Willner, A; Düsterer, S; Prandolini, M J; Feldhaus, J; Faatz, B; Rossbach, J; Drescher, M; Tavella, F

    2012-02-27

    An Yb:YAG thin-disk multipass laser amplifier system was developed operating in a 10 Hz burst operation mode with 800 µs burst duration and 100 kHz intra-burst repetition rate. Methods for the suppression of parasitic amplified spontaneous emission are presented. The average output pulse energy is up to 44.5 mJ and 820 fs compressed pulse duration. The average power of 4.45 kW during the burst is the highest reported for this type of amplifier. PMID:22418308

  2. Neutron emission as a function of fragment energy in the spontaneous fission of 260Md

    International Nuclear Information System (INIS)

    The authors have made the first measurement of the number of neutrons emitted in the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of 254Es, they produced 28-d 260Md, which was neutron-counted in a 1-m-diam spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58 ± 0.11, substantially less than for other actinides. A direct correlation of neutron multiplicity with fragment excitation energy is clearly demonstrated

  3. Noise Gain Features of Fiber Raman Amplifier

    Directory of Open Access Journals (Sweden)

    Georgii S. Felinskyi

    2016-01-01

    Full Text Available The formation dynamics of the optical noise in a silica single mode fiber (SMF as function of the pump power variation in the counter pumped fiber Raman amplifier (FRA is experimentally studied. The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data in the pump powers range of 100–300 mW within the full band of Stokes frequencies, including FRA working wavelengths over the C + L transparency windows. It is found out the maximum of Raman gain coefficient for optical noise does not exceed ~60% of corresponding peak at the gain profile maximum of coherent signal. It is shown that the real FRA noise figure may be considerably less than 3 dB over a wide wavelength range (100 nm at a pump power of several hundreds of mW.

  4. Measurement of the stimulated carrier lifetime in semiconductor optical amplifiers by four-wave mixing of polarized ASE noise

    OpenAIRE

    Hunziker, Guido; Paiella, Roberto; Vahala, Kerry J.; Koren, Uzi

    1997-01-01

    We present a simple experiment aimed at measuring the stimulated carrier lifetime in semiconductor optical amplifiers (SOA's). The technique relies on polarization-resolved nearly degenerate four-wave mixing (FWM) of a laser source with an amplified spontaneous emission (ASE) noise source. The method can quickly characterize the bandwidth performance of active layers for application in a cross-gain or cross-phase wavelength converter.

  5. Generation of intense 10-ps, 193-nm pulses using simple distributed feedback dye lasers and an ArF(*) amplifier.

    Science.gov (United States)

    Hatten, D L; Cui, Y; Iii, W T; Mikes, T; Goldhar, J

    1992-11-20

    A pair of holographic distributed feedback dye lasers is used to generate 10-ps pulses at two selected wavelengths that are mixed in a BBO crystal to produce a pulse ~ 10 ps in duration at 193 nm. This seed pulse is subsequently amplified in an ArF(*) excimer laser to an energy of 10-15 mJ with <40 microJ in amplified spontaneous emission. The pulses are nearly transform limited and diffraction limited. PMID:20802565

  6. DETERMINATION OF THE SPONTANEOUS EMISSION PROBABILITIES AND THE COLLISION SELF-BROADENING COEFFICIENTS OF THE СО2 SPECTRAL LINES

    Directory of Open Access Journals (Sweden)

    K. I. Arshinov

    2015-03-01

    Full Text Available The technique of simultaneous determination of the spontaneous emission probabilities Аmn and the collision self-broadening coefficients γmn of the СО2 spectral lines is presented. The dependence of the absorption coefficient on the gas pressure, obtained for the СО210R22 line at temperature 300 K was measured. Using the data, the spontaneous emission probability Аmn and the collision self-broadening coefficient γmn were calculated.

  7. Terahertz-range spontaneous emission under the optical excitation of donors in uniaxially stressed bulk silicon and SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhukavin, R. Kh., E-mail: zhur@ipmras.ru; Kovalevsky, K. A.; Orlov, M. L.; Tsyplenkov, V. V.; Bekin, N. A.; Yablonskiy, A. N.; Yunin, P. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Pavlov, S. G. [German Aerospace Center (DLR), Institute of Planetary Research (Germany); Abrosimov, N. V. [Leibniz Institute for Crystal Growth (Germany); Hübers, H.-W. [German Aerospace Center (DLR), Institute of Planetary Research (Germany); Radamson, H. H. [Royal Institute of Technology (KTH) (Sweden); Shastin, V. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

    2015-01-15

    The results of measurements of the total terahertz-range photoluminescence of Group-V donors (phosphorus, antimony, bismuth, arsenic) in bulk silicon and SiGe/Si heterostructures depending on the excitation intensity are presented. The signal of bulk silicon was also measured as a function of uniaxial stress. The results of measurement of the dependence of the spontaneous emission intensity on the uniaxial stress is in rather good agreement with theoretical calculations of the relaxation times of excited states of donors in bulk silicon. Comparative measurements of the spontaneous emission from various strained heterostructures showed that the photoluminescence signal is caused by donor-doped silicon regions.

  8. Spontaneous emission interference enhancement with a μ-negative metamaterial slab

    International Nuclear Information System (INIS)

    The spontaneous decay and quantum interference of a V-type Zeeman atom placed near a μ-negative metamaterial (MNG) slab are investigated. Based on the fact that MNG slab supports only TE-polarized surface-plasmon polariton (SPP) modes, the decay rate of the dipole component parallel to the interface would be much larger than that normal to the interface, because one can couple while another decouple to TE modes. Consequently, high-level anisotropic environment is created and the two dipoles can interfere with each other strongly by sharing such SPP modes even if they are orthogonal. In our work, we analyze the influence of the parameters of the MNG slab as well as the atomic location on the interference intensity in detail. In addition, the dissipation of the slab is considered, and the quantum interference is still excellent even with large absorption.

  9. Spectral broadening effects of spontaneous emission and density of state on plasmonic enhancement in cermet waveguides.

    Science.gov (United States)

    Chen, Keyong; Feng, Xue; Zhang, Chao; Cui, Kaiyu; Huang, Yidong

    2013-01-14

    Based on the full integration formula of Purcell factor (PF) deduced from Fermi's Golden Rule, the plasmonic enhancement in Au(1-α)S3N4(α) cermet waveguides is evaluated with the joint impact of finite emission linewidth and the broadening of PF spectrum. The calculation results indicate that the PF would be significantly degraded by the two broadening effects though the SPP resonance frequency can be tuned with different volume fractions (α) of Si3N4. It is also found that the critical emission linewidth is approximately linear to the PF spectrum linewidth. Thus in order to achieve strong plasmonic enhancement, both the emission and PF spectrum linewidths should be dramatically reduced. PMID:23388935

  10. Broadband enhancement of spontaneous emission from nitrogen-vacancy centers in nanodiamonds by hyperbolic metamaterials

    CERN Document Server

    Shalaginov, M Y; Liu, J; Liu, J; Irudayaraj, J; Lagutchev, A; Kildishev, A V; Shalaev, V M

    2013-01-01

    We experimentally demonstrate a broadband enhancement of emission from nitrogen vacancy centers in nanodiamonds. The enhancement is achieved by using a multilayer metamaterial with hyperbolic dispersion. The metamaterial is fabricated as a stack of alternating gold and alumina layers. Our approach paves the way towards the construction of efficient single-photon sources as planar on-chip devices.

  11. Yb:YAG master oscillator power amplifier for remote wind sensing.

    Science.gov (United States)

    Sridharan, A K; Saraf, S; Byer, R L

    2007-10-20

    We have demonstrated key advances towards a solid-state laser amplifier at 1.03 microm for global remote wind sensing. We designed end-pumped zig-zag slab amplifiers to achieve high gain. We overcame parasitic oscillation limitations using claddings on the slab's total internal reflection (TIR) and edge surfaces to confine the pump and signal light by TIR and allow leakage of amplified spontaneous emission rays that do not meet the TIR condition. This enables e3, e5, and e8 single-, double-, and quadruple-pass small-signal amplifier gain, respectively. The stored energy density is 15.6 J/cm3, a record for a laser-diode end-pumped Yb:YAG zig-zag slab amplifier. PMID:17952195

  12. High energy {gamma} emission in the spontaneous fission of {sup 252}Cf; Emission {gamma} de grande energie dans la fission spontanee de {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Badimon, C.; Barreau, G.; Doan, T.P.; Pedemay, G. [Centre d`Etudes Nucleaires, Bordeaux-1 Univ., 33 Gradignan (France); Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Thiesen, Ch. [Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Belier, G.; Meot, M.V. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France); Astier, A.; Ducroux, L.; Meyer, M.; Redon, N. [Inst.de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1997-06-01

    The prompt {gamma} emission in the spontaneous fission of {sup 252}Cf is characterized by an energy spectrum which extends up to 20 MeV. It was established that the spectrum presents in the neighbourhood of symmetric fission an intensity bump in the 3-8 MeV {gamma} energy interval. The origin of this phenomenon is still not well understood, so that it was found interesting to carry out new measurements. The spectrum of the {gamma} rays emitted in spontaneous fission of {sup 252}Cf has been measurement in the EUROGAM II multidetector using photovoltaic cells to detect fragments. The aim of the experiment was to investigate the {gamma} yield enhancement which appears for mass fragment ratio near 132/120. This enhancement was found to be composed of two peaks located at 4 MeV and 5.5 MeV respectively. The results obtained confirm the intensity bound in the 3-8 MeV region but this augmentation reaches the maximum when the heavy fragment is near the mass 132. Beyond mass 140 the phenomenon diminish and the {gamma} spectrum regains the behaviour expected for a statistic emission. The additional structure at 5.5 MeV does not vary with excitation energy while the excitation function of the 4 MeV structure is more structured and presents a maximum when the excitation energy is near 8 MeV. It is likely that all or part of this observed phenomenon is due to a particular excitation mode of this isotope associated for instance with a low energy dipole resonance. A theoretical study of this collective effect is under way 3 refs.

  13. The research and implementation of coalfield spontaneous combustion of carbon emission WebGIS based on Silverlight and ArcGIS server

    International Nuclear Information System (INIS)

    As an important sub-topic of the natural process of carbon emission data public information platform construction, coalfield spontaneous combustion of carbon emission WebGIS system has become an important study object. In connection with data features of coalfield spontaneous combustion carbon emissions (i.e. a wide range of data, which is rich and complex) and the geospatial characteristics, data is divided into attribute data and spatial data. Based on full analysis of the data, completed the detailed design of the Oracle database and stored on the Oracle database. Through Silverlight rich client technology and the expansion of WCF services, achieved the attribute data of web dynamic query, retrieval, statistical, analysis and other functions. For spatial data, we take advantage of ArcGIS Server and Silverlight-based API to invoke GIS server background published map services, GP services, Image services and other services, implemented coalfield spontaneous combustion of remote sensing image data and web map data display, data analysis, thematic map production. The study found that the Silverlight technology, based on rich client and object-oriented framework for WCF service, can efficiently constructed a WebGIS system. And then, combined with ArcGIS Silverlight API to achieve interactive query attribute data and spatial data of coalfield spontaneous emmission, can greatly improve the performance of WebGIS system. At the same time, it provided a strong guarantee for the construction of public information on China's carbon emission data

  14. The research and implementation of coalfield spontaneous combustion of carbon emission WebGIS based on Silverlight and ArcGIS server

    Science.gov (United States)

    Zhu, Z.; Bi, J.; Wang, X.; Zhu, W.

    2014-02-01

    As an important sub-topic of the natural process of carbon emission data public information platform construction, coalfield spontaneous combustion of carbon emission WebGIS system has become an important study object. In connection with data features of coalfield spontaneous combustion carbon emissions (i.e. a wide range of data, which is rich and complex) and the geospatial characteristics, data is divided into attribute data and spatial data. Based on full analysis of the data, completed the detailed design of the Oracle database and stored on the Oracle database. Through Silverlight rich client technology and the expansion of WCF services, achieved the attribute data of web dynamic query, retrieval, statistical, analysis and other functions. For spatial data, we take advantage of ArcGIS Server and Silverlight-based API to invoke GIS server background published map services, GP services, Image services and other services, implemented coalfield spontaneous combustion of remote sensing image data and web map data display, data analysis, thematic map production. The study found that the Silverlight technology, based on rich client and object-oriented framework for WCF service, can efficiently constructed a WebGIS system. And then, combined with ArcGIS Silverlight API to achieve interactive query attribute data and spatial data of coalfield spontaneous emmission, can greatly improve the performance of WebGIS system. At the same time, it provided a strong guarantee for the construction of public information on China's carbon emission data.

  15. Quantum Interference in Spontaneous Emission from a V-Type Three-Level Atom in a Two-Band Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    YANG Ya-Ping; Chen Hong; ZHU Shi-Yao

    2000-01-01

    The spontaneous emission from a V-type three-level atom embedded in a two-band photonic crystal is studied.Due to the quantum interference between the two transitions and existence of two bands, the populations in the upper levels display some novel behavior: anti-trapping, population oscillation, and population inversion.

  16. Characterization of the Spontaneous Light Emission of the PMTs used in the Double Chooz Experiment

    OpenAIRE

    Double Chooz collaboration; Abe, Y; Abrahão, T.; Almazan, H.; Alt, C.; Appel, S.; Baussan, E.; Bekman, I.(III. Physikalisches Institut, RWTH Aachen University, 52056, Aachen, Germany); Bergevin, M.; Bezerra, T. J. C.; BEZRUKOV L.; Blucher, E.; Brugière, T.; Buck, C.; Busenitz, J.

    2016-01-01

    During the commissioning of the first of the two detectors of the Double Chooz experiment, an unexpected and dominant background caused by the emission of light inside the optical volume has been observed. A specific study of the ensemble of phenomena called "Light Noise" has been carried out in-situ, and in an external laboratory, in order to characterize the signals and to identify the possible processes underlying the effect. Some mechanisms of instrumental noise originating from the PMTs ...

  17. Enhancement and Inhibition of Spontaneous Photon Emission by Resonant Silicon Nanoantennas

    CERN Document Server

    Bouchet, Dorian; Proust, Julien; Gallas, Bruno; Ozerov, Igor; Garcia-Parajo, Maria F; Gulinatti, Angelo; Rech, Ivan; De Wilde, Yannick; Bonod, Nicolas; Krachmalnicoff, Valentina; Bidault, Sébastien

    2016-01-01

    We demonstrate that subwavelength silicon resonators can increase and decrease the emission decay rates of fluorescent molecules at room temperature. Using scanning probe microscopy, we analyze the near-field interaction between a fluorescent nanosphere and silicon nanodisks in three dimensions, highlighting the ability of dielectric antennas to increase the far-field collection of emitted photons, in excellent agreement with numerical simulations. Our study demonstrates the potential of silicon-based resonators for the low-loss manipulation of solid-state emitters at the nanoscale.

  18. Characterization of the Spontaneous Light Emission of the PMTs used in the Double Chooz Experiment

    CERN Document Server

    Abe, Y; Almazan, H; Alt, C; Appel, S; Baussan, E; Bekman, I; Bergevin, M; Bezerra, T J C; Bezrukov, L; Blucher, E; Brugière, T; Buck, C; Busenitz, J; Cabrera, A; Calvo, E; Camilleri, L; Carr, R; Cerrada, M; Chauveau, E; Chimenti, P; Collin, A P; Conover, E; Conrad, J M; Crespo-Anadón, J I; Crum, K; Cucoanes, A S; Damon, E; Dawson, J V; de Kerret, H; Dhooghe, J; Dietrich, D; Djurcic, Z; Anjos, J C dos; Dracos, M; Etenko, A; Fallot, M; Felde, J; Fernandes, S M; Fischer, V; Franco, D; Franke, M; Furuta, H; Gil-Botella, I; Giot, L; Göger-Neff, M; Gomez, H; Gonzalez, L F G; Goodenough, L; Goodman, M C; Haag, N; Hara, T; Haser, J; Hellwig, D; Hofmann, M; Horton-Smith, G A; Hourlier, A; Ishitsuka, M; Jiménez, S; Jochum, J; Jollet, C; Kaether, F; Kalousis, L N; Kamyshkov, Y; Kaneda, M; Kaplan, D M; Kawasaki, T; Kemp, E; Kryn, D; Kuze, M; Lachenmaier, T; Lane, C E; Lasserre, T; Letourneau, A; Lhuillier, D; Lima, H P; Lindner, M; López-Castaño, J M; LoSecco, J M; Lubsandorzhiev, B; Lucht, S; Maeda, J; Mariani, C; Maricic, J; Martino, J; Matsubara, T; Mention, G; Meregaglia, A; Miletic, T; Milincic, R; Minotti, A; Nagasaka, Y; Navas-Nicolás, D; Novella, P; Nunokawa, H; Oberauer, L; Obolensky, M; Onillon, A; Osborn, A; Palomares, C; Pepe, I M; Perasso, S; Porta, A; Pronost, G; Reichenbacher, J; Reinhold, B; Röhling, M; Roncin, R; Rybolt, B; Sakamoto, Y; Santorelli, R; Schilithz, A C; Schönert, S; Schoppmann, S; Shaevitz, M H; Sharankova, R; Shrestha, D; Sibille, V; Sinev, V; Skorokhvatov, M; Smith, E; Soiron, M; Spitz, J; Stahl, A; Stancu, I; Stokes, L F F; Strait, M; Suekane, F; Sukhotin, S; Sumiyoshi, T; Sun, Y; Svoboda, R; Terao, K; Tonazzo, A; Thi, H H Trinh; Valdiviesso, G; Vassilopoulos, N; Veyssiere, C; Vivier, M; von Feilitzsch, F; Wagner, S; Walsh, N; Watanabe, H; Wiebusch, C; Wurm, M; Yang, G; Yermia, F; Zimmer, V

    2016-01-01

    During the commissioning of the first of the two detectors of the Double Chooz experiment, an unexpected and dominant background caused by the emission of light inside the optical volume has been observed. A specific study of the ensemble of phenomena called "Light Noise" has been carried out in-situ, and in an external laboratory, in order to characterize the signals and to identify the possible processes underlying the effect. Some mechanisms of instrumental noise originating from the PMTs were identified and it has been found that the leading one arises from the light emission localized on the photomultiplier base and produced by the combined effect of heat and high voltage across the transparent epoxy resin covering the electric components. The correlation of the rate and the amplitude of the signal with the temperature has been observed. For the first detector in operation the induced background has been mitigated using online and offline analysis selections based on timing and light pattern of the signa...

  19. Spontaneous and stimulated emission in Sm3+-doped YAl3(BO3)4 single crystal

    International Nuclear Information System (INIS)

    Single crystals of YAl3(BO3)4 doped with trivalent samarium were grown by the top-seeded high temperature solution method and their absorption and emission spectra were investigated. Optical pumping into prominent absorption band around 405 nm feeds the 4G5/2 metastable level giving rise to intense visible luminescence distributed in several spectral lines with the most intense line around 600 nm characterized by a branching ratio of 0.42 and peak emission cross section of 0.25×10−20 cm2. Optical amplification at 600 nm with a gain coefficient of 2.9 cm−1 was achieved during a pump-and-probe experiment. - Highlights: • YAB:Sm crystal grown by the top-seeded high temperature solution method. • Spectroscopic qualities relevant for visible laser operation. • YAB:Sm single crystal used in a pump-and-probe experiment. • Optical amplification properties of samarium doped YAl3(BO3)4

  20. A picosecond thin-rod Yb:YAG regenerative laser amplifier with the high average power of 20 W

    International Nuclear Information System (INIS)

    A high-average-power, laser-diode-pumped, picosecond-pulse regenerative amplifier was developed using the thin-rod Yb:YAG (yttrium aluminum garnet) laser architecture. This architecture has a complete set of favorable properties for the cost-effective, high-average-power, and high-peak-power lasers. These include low amplified spontaneous emission with high gain and high repetition rate. For the amplifier system, an average output power of 20 W was achieved at a pulse repetition rate of 100 kHz, which corresponds to an output pulse energy of 200 μJ with an output pulse width of 2 ps. (letter)

  1. Generation of coherent soft x-rays using a single-pass free-electron laser amplifier

    International Nuclear Information System (INIS)

    We consider a single-pass free-electron laser (FEL) amplifier, driven by an rf-linac followed by a damping ring for reduced emittance, for use in generating coherent light in the soft x-ray region. The dependence of the optical gain on electron-beam quality, studied with the three-dimensional FEL simulation code FELEX, is given and related to the expected power of self-amplified spontaneous emission. We discuss issues for the damping ring designed to achieve the required electron beam quality. The idea of a multipass regenerative amplifier is also presented

  2. A picosecond thin-rod Yb:YAG regenerative laser amplifier with the high average power of 20 W

    Science.gov (United States)

    Matsubara, S.; Tanaka, M.; Takama, M.; Hitotsuya, H.; Kobayashi, T.; Kawato, S.

    2013-05-01

    A high-average-power, laser-diode-pumped, picosecond-pulse regenerative amplifier was developed using the thin-rod Yb:YAG (yttrium aluminum garnet) laser architecture. This architecture has a complete set of favorable properties for the cost-effective, high-average-power, and high-peak-power lasers. These include low amplified spontaneous emission with high gain and high repetition rate. For the amplifier system, an average output power of 20 W was achieved at a pulse repetition rate of 100 kHz, which corresponds to an output pulse energy of 200 μJ with an output pulse width of 2 ps.

  3. Even–odd effects in prompt emission of spontaneously fissioning even–even Pu isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tudora, A., E-mail: anabellatudora@hotmail.com [University of Bucharest, Faculty of Physics, Bucharest Magurele, POB MG-11, R-76900 (Romania); Hambsch, F.-J. [EC-JRC Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440, Geel (Belgium); Giubega, G.; Visan, I. [University of Bucharest, Faculty of Physics, Bucharest Magurele, POB MG-11, R-76900 (Romania)

    2015-01-15

    The available experimental Y(A,TKE) data for {sup 236,238,240,242,244}Pu(SF) together with the Zp model prescription with appropriate parameters allows the investigation of even–odd effects in fragment distributions. The size of the global even–odd effect in Y(Z) is decreasing from {sup 244}Pu(SF) to {sup 236}Pu(SF) confirming the general observation of a decrease of the even–odd effect with the fissility parameter. Charge polarizations (ΔZ) and root-mean squares (rms) as a function of A of {sup 236–244}Pu(SF) were obtained for the first time. In the asymmetric fission region both ΔZ(A) and rms(A) exhibit oscillations with a periodicity of about 5 mass units due to the even–odd effects. The total average charge deviations 〈ΔZ〉 (obtained by averaging ΔZ(A) over the experimental Y(A) distribution) are of about |0.5| for all studied Pu(SF) systems. The comparison of the calculated ΔZ(A) and rms(A) of {sup 240}Pu(SF) with those of {sup 239}Pu(n{sub th},f) reported by Wahl shows an in-phase oscillation with a higher amplitude in the case of {sup 240}Pu(SF), confirming the higher even–odd effect in the case of SF. As in the previously studied cases ({sup 233,235}U(n{sub th},f), {sup 239}Pu(n{sub th},f), {sup 252}Cf(SF)) the even–odd effects in the prompt emission of {sup 236–244}Pu(SF) are mainly due to the Z even–odd effects in fragment distributions and charge polarizations and the N even–odd effects in the average neutron separation energies from fragments 〈Sn〉. The size of the global N even–odd effect in 〈Sn〉 is decreasing with the fissility parameter, being higher for the Pu(SF) systems compared to the previously studied systems. The prompt neutron multiplicities as a function of Z, ν(Z), exhibit sawtooth shapes with a visible staggering for asymmetric fragmentations. The size of the global Z even–odd effect in ν(Z) exhibits a decreasing trend with increasing fissility. The average prompt neutron multiplicities as a

  4. Operational amplifiers

    CERN Document Server

    Dostal, Jiri

    1993-01-01

    This book provides the reader with the practical knowledge necessary to select and use operational amplifier devices. It presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits.Provides the reader with practical knowledge necessary to select and use operational amplifier devices. Presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits

  5. High average power picoseconds fiber amplifier with 20 μm core YDF

    International Nuclear Information System (INIS)

    In this letter we report a simple single-stage amplifier realized as high as 62 W average power output at 1064 nm wavelength, 40 picoseconds pulse width and 80 MHz repetition from 0.7 W seed laser based on backward pumped master-oscillator fiber power amplifier (MOPA) system. It is can stable operation in 57.6 W output for hours. We applied a semiconductor saturable absorber mirror (SESAM) passive mode-lock Nd:YVO4 oscillator as seed source and 6m long 20 μm core double-cladding Yb-doped fiber (YDF) as gain medium. To the best of our knowledge, 62 W average power is the highest output of single-stage ps-pulse amplifier with 20 μm-core fiber. None amplified spontaneous emission (ASE) and stimulated Raman scattering (SRS) nonlinear phenomenon was observed in 57.6 W high average power output

  6. High power pulse amplification of ytterbium-doped double-clad fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Liping Chang; Wei Fan; Jialin Chen; Li Wang; Bai Chen; Zunqi Lin

    2007-01-01

    By solving a set of time-dependent equations, the characteristics of the ytterbium-doped double-clad fiber amplifier are presented. Besides the steady state in the fiber of the upper-state population, pump power and amplified spontaneous emission without the input signal, the dynamic characteristics of the high power Gaussian pulse amplification like the evolution of pulse waveform distortion, upper-state population distribution and stored energy and pulse energy of the amplifier under the forward and backward pump,are simulated. The relations between the output pulse energy of the amplifier and the different input pulse peak power or pump power are also discussed. The models and results can provide important guide for the design and optimization of the high power pulse amplification.

  7. Terahertz Emission from Resonant Tunneling Diodes without Satisfying Oscillation Condition

    Science.gov (United States)

    Asada, Masahiro; Kanaya, Hidetoshi; Suzuki, Safumi

    2013-10-01

    Terahertz (THz) emission from resonant tunneling diodes (RTDs) is normally obtained under the oscillation condition in which the negative differential conductance (NDC) exceeds the circuit loss. In this study, we show that a relatively broad band THz emission was observed even for RTDs with an NDC smaller than the circuit loss. The observed output power was on the order of 1-10 nW at 1.2-1.9 THz with spectral widths of 50-100 GHz. The observation was reasonably explained by the theoretical calculation based on the shot noise amplified by the NDC. This emission corresponds to the amplified spontaneous emission in optical devices.

  8. ASE suppression in high-gain solid-state amplifiers by a leak method

    International Nuclear Information System (INIS)

    A leak method was developed to suppress amplified spontaneous emission (ASE) in large-aperture high-gain solid-state amplifiers. The gain medium edges are processed into an arris. The ASE ray will undergo reflection several times at the arris surface when it propagates to the gain medium edges, and most of its power will leak out. This leak method was tested in an experiment, in which a piece of commonly used gain medium was processed for contrast. The maximal increase of the gain value was 5.26% with the maximal pump power. (paper)

  9. ASE suppression in high-gain solid-state amplifiers by a leak method

    Science.gov (United States)

    Zhang, Yongliang; Ye, Haixian; Li, Mingzhong; Zheng, Jiangang; Wei, Xiaofeng; Gao, Song; Deng, Qinghua; Jiang, Xinying; Yan, Xiongwei; Wang, Zhenguo

    2013-07-01

    A leak method was developed to suppress amplified spontaneous emission (ASE) in large-aperture high-gain solid-state amplifiers. The gain medium edges are processed into an arris. The ASE ray will undergo reflection several times at the arris surface when it propagates to the gain medium edges, and most of its power will leak out. This leak method was tested in an experiment, in which a piece of commonly used gain medium was processed for contrast. The maximal increase of the gain value was 5.26% with the maximal pump power.

  10. 13.9-mJ all fiber wide band ytterbium-doped fiber amplifier

    International Nuclear Information System (INIS)

    We report a wide bandwidth with full width at half maximum (FWHM) of about 10 nm pulsed all-fiber master oscillator power amplifier (MOPA) incoherent source emitting 13.91 mJ pulses (1.16 MW peak power) for 12 ns duration at the repetition rate lower than 100 Hz. In order to increase the efficiency and suppress amplified spontaneous emission (ASE), multi-stage pulse pump technology is applied. And different pump width and signal duration amplification characteristics were measured. A totally about 90 dB gain is obtained. And this system is possibly utilized in fiber-based inertial fusion laser driver

  11. A broadly tunable fiber ring laser employing a gain-clamped semiconductor optical amplifier

    International Nuclear Information System (INIS)

    A widely tunable fiber ring laser is demonstrated experimentally using a specially designed gain-clamped semiconductor optical amplifier (GC-SOA). The 3 dB bandwidth of the generated amplified spontaneous emission is increased by 10 nm using the GC-SOA. The lasing wavelength is continuously tunable in a range from 1522 nm to almost 1600 nm using a thin-film Fabry–Pérot tunable filter. A side-mode-suppression ratio of greater than 55 dB is achieved over the entire tuning range. (paper)

  12. Cryogenic Yb:YAG composite-thin-disk for high energy and average power amplifiers

    OpenAIRE

    Zapata, Luis E.; Lin, Hua; Calendron, Anne-Laure; Cankaya, Huseyin; Hemmer, Michael; Reichert, Fabian; Huang, W. Ronny; Granados, Eduardo; Hong, Kyung-Han; Kärtner, Franz X.

    2015-01-01

    A cryogenic composite-thin-disk amplifier with amplified spontaneous emission (ASE) rejection is implemented that overcomes traditional laser system problems in high-energy pulsed laser drivers of high average power. A small signal gain of 8 dB was compared to a 1.5 dB gain for an uncapped thin-disk without ASE mitigation under identical pumping conditions. A strict image relayed 12-pass architecture using an off-axis vacuum telescope and polarization switching extracted 100 mJ at 250 Hz in h...

  13. External-cavity high-power dual-wavelength tapered amplifier with tunable THz frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    achieved with a frequency difference of 0.86 THz, the output power is higher than 1.3 W in the 5.0 THz range of frequency difference, and the amplified spontaneous emission intensity is more than 20 dB suppressed in the range of frequency difference. The beam quality factor M2 is 1.22±0.15 at an output...

  14. Light emission from thulium silicates and oxides for optical amplifiers on silicon in the extended optical communications band

    Directory of Open Access Journals (Sweden)

    Hiroo Omi

    2013-07-01

    Full Text Available Films composed of Tm2Si2O7 and Tm2O3 grains formed on SiO2/Si substrates by radio magnetic sputtering and subsequent thermal annealing up to 1250 °C were characterized by synchrotron grazing incidence X-ray diffraction, cross-sectional transmission microscopy, and micro photoluminescence (PL measurements. The films composed of triclinic (type-B and monoclinic (type-C Tm2Si2O7 grains on SiO2/Si and Tm2O3 grains on Si exhibit photoluminescence at the wavelength of about 1620 nm for the silicates and 1630 nm for the oxide, which indicates that they have good potential as light amplifiers on Si in the L and U bands at telecommunications wavelengths.

  15. Spontaneous emission control of silicon nanocrystals by silicon three-dimensional photonic crystal structure fabricated by self-aligned two-directional electrochemical etching method

    International Nuclear Information System (INIS)

    A silicon three-dimensional photonic crystal (3DPC) structure has been fabricated using a self-aligned, two-directional electrochemical etching method. The spectral component of the photoluminescence (PL) for silicon nanocrystals deposited on the 3DPC structures increase at 750 nm and slightly decrease at 800 nm. Time-resolved PL measurements reveal that the radiative recombination lifetime of the silicon nanocrystals on 3DPC structures decreases at 750 nm and increases at 800 nm compared to those on a silicon substrate without 3DPC structures. We conclude that the spontaneous emission control of silicon nanocrystals has been observed using the 3DPC structures.

  16. Emission of orbital-angular-momentum-entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion

    Czech Academy of Sciences Publication Activity Database

    Javůrek, D.; Svozilík, J.; Peřina ml., Jan

    2014-01-01

    Roč. 90, č. 4 (2014), "043844-1"-"043844-12". ISSN 1050-2947 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : photon pairs * orbital-angular-momentum-entangled * nonlinear ring fiber * spontaneous parametric down-conversion Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.808, year: 2014

  17. Brain glucose metabolic changes associated with chronic spontaneous Pain due to brachial plexus avulsion:a preliminary positron emission tomography study

    Institute of Scientific and Technical Information of China (English)

    CHEN Fu-yong; TAO Wei; CHENG Xin; WANG Hong-yan; HU Yong-sheng; ZHANG Xiao-hua; LI Yong-jie

    2008-01-01

    Background Previous brain imaging studies suggested that the brain activity underlying the perception of chronic pain maV differ from that underlying acute pain.To investigate the brain regions involved in chronic spontaneous pain due to brachial plexus avulsion(BPA),fluorine-18fluorodeoxygIucose (19F-FDG) positron emission tomography (PET) scanning was applied to determine the glucose metabolic changes in patients with pain due to BPA.Methods Six right-handed patients with chronic spontaneous pain due to left-BPA and twelve right-handed age-and sex-matched healthy control subjects participated in the 18F-FDG PET study.The patients were rated by visual analog scale (VAS) during scanning and Hamilton depression scale and Hamilton anxiety scale after scanning.Statistical parametric mapping 2 (SPM2) was applied for data analysis.Results Compared with healthy subjects,the patients had significant glucose metabolism decreases in the right thalamus and S I(P<0.001,uncorrected),and significant glucose metabolism increases in the right orbitofrontaI cortex (OFC) (BA11),left rostral insula cortex and left dorsolateral prefrontal codex (DLPFC) (BA10/46) (P<0.001,uncorrected).Conclusion These findings suggest that the brain areas involved in emotion.aRention and internal modulation of pain may be related to the chronic spontaneous pain due to BPA.

  18. Characterization of a high-power tapered semiconductor amplifier system

    CERN Document Server

    Voigt, D; Spreeuw, R J C; Van Linden van den Heuvell, H B

    2001-01-01

    We have characterized a semiconductor amplifier laser system which provides up to 200mW output after a single-mode optical fiber at 780nm wavelength. The system is based on a tapered semiconductor gain element, which amplifies the output of a narrow-linewidth diode laser. Gain and saturation are discussed as a function of operating temperature and injection current. The spectral properties of the amplifier are investigated with a grating spectrometer. Amplified spontaneous emission (ASE) causes a spectral background with a width of 4nm FWHM. The ASE background was suppressed to below our detection limit by a proper choice of operating current and temperature, and by sending the light through a single-mode optical fiber. The final ASE spectral density was less than 0.1nW/MHz, i.e. less than 0.2 % of the optical power. Related to an optical transition linewidth of $\\Gamma/2\\pi=6$ MHz for rubidium, this gives a background suppression of better than -82dB. An indication of the beam quality is provided by the fibe...

  19. Annual Change Detection by ASTER TIR Data and an Estimation of the Annual Coal Loss and CO2 Emission from Coal Seams Spontaneous Combustion

    Directory of Open Access Journals (Sweden)

    Xiaomin Du

    2014-12-01

    Full Text Available Coal fires, including both underground and coal waste pile fires, result in large losses of coal resources and emit considerable amounts of greenhouse gases. To estimate the annual intensity of greenhouse gas emissions and the loss of coal resources, estimating the annual loss from fire-influenced coal seams is a feasible approach. This study assumes that the primary cause of coal volume loss is subsurface coal seam fires. The main calculation process is divided into three modules: (1 Coal fire quantity calculations, which use change detection to determine the areas of the different coal fire stages (increase/growth, maintenance/stability and decrease/shrinkage. During every change detections, the amount of coal influenced by fires for these three stages was calculated by multiplying the coal mining residual rate, combustion efficiency, average thickness and average coal intensity. (2 The life cycle estimate is based on remote sensing long-term coal fires monitoring. The life cycles for the three coal fire stages and the corresponding life cycle proportions were calculated; (3 The diurnal burnt rates for different coal fire stages were calculated using the CO2 emission rates from spontaneous combustion experiments, the coal fire life cycle, life cycle proportions. Then, using the fire-influenced quantity aggregated across the different stages, the diurnal burn rates for the different stages and the time spans between the multi-temporal image pairs used for change detection, we estimated the annual coal loss to be 44.3 × 103 tons. After correction using a CH4 emission factor, the CO2 equivalent emissions resulting from these fires was on the order of 92.7 × 103 tons. We also discovered that the centers of these coal fires migrated from deeper to shallower parts of the coal seams or traveled in the direction of the coal seam strike. This trend also agrees with the cause of the majority coal fires: spontaneous combustion of coalmine goafs.

  20. High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm

    CERN Document Server

    Stappel, M; Kolbe, D; Walz, J

    2012-01-01

    We present a high power single-frequency ytterbium fiber amplifier system with an output power of 30 W at 1091 nm. The amplifier system consists of two stages, a preamplifier stage in which amplified spontaneous emission is efficiently suppressed (>40 dB) and a high power amplifier with an efficiency of 52 %. Two different approaches of frequency doubling are compared. We achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped periodically poled stoichiometric LiTaO3 and up to 19.3 W at 545.5 nm by frequency doubling with a lithium-triborate (LBO) crystal in an external enhancement cavity.

  1. The Quantum Vacuum of Complex Media. A Unified Approach to the Dielectric Constant, the Spontaneous Emission and the Zero-Temperature Electromagnetic Pressure

    CERN Document Server

    Donaire, M

    2009-01-01

    We study from a critical perspective several quantum-electrodynamic phenomena commonly related to vacuum electromagnetic (EM) fluctuations in complex media. We compute the resonance-shift, the spontaneous emission rate, the local density of states and the van-der-Waals-Casimir pressure in a dielectric medium using a microscopic diagrammatic approach. We find, in agreement with some recent works, that these effects cannot be attributed to variations on the energy of the EM vacuum but to variations of the dielectric self-energy. This energy is the result of the interaction of the bare polarizability of the dielectric constituents with the EM fluctuations of an actually polarized vacuum. We have found an exact expression for the spectrum of these fluctuations in a statistically homogeneous dielectric. Those fluctuations turn out to be different to the ones of normal radiative modes. It is the latter that carry the zero-point-energy (ZPE). Concerning spontaneous emission, we clarify the nature of the radiation an...

  2. Performance of a 100J cryogenically cooled multi-slab amplifier with respect to the pump beam parameters and geometry

    Czech Academy of Sciences Publication Activity Database

    Divoký, Martin; Sawicka, Magdalena; Lucianetti, Antonio; Novák, Jakub; Mocek, Tomáš; Rus, Bedřich

    Bellingham : SPIE, 2012 - (Clarkson, W.; Shori, R.) ISBN 978-0-8194-8878-7. ISSN 0277-786X. - (Proceedings of SPIE. 8235). [Conference on Solid State Lasers - Technology and Devices /21./. San Francisco (US), 22.01.2012-25.01.2012] R&D Projects: GA MŠk ED2.1.00/01.0027 Grant ostatní: HILASE(XE) CZ.1.05/2.1.00/01.0027 Institutional support: RVO:68378271 Keywords : multi-slab * amplifier * cryogenical cooling * amplified spontaneous emission Subject RIV: BH - Optics, Masers, Lasers

  3. UV x-ray free electron lasers through high-gain single pass amplifier: Basic principles and issues

    International Nuclear Information System (INIS)

    The author reviews the basic principles of high gain free electron laser amplifier in single pass configuration for generation of intense, tunable radiation for wavelength shorter than 1,000 angstrom. Two schemes are discussed: for wavelength region between 1,000--100 angstrom, the high gain harmonic generation of a coherent input radiation can be used. For x-ray wavelength as short as a few angstrom, the self-amplified spontaneous emission is currently the only known free electron laser scheme. The author also presents a brief introduction of various key issues in realizing these schemes, which will be discussed in detail in other papers in these proceedings

  4. Modeling of high-quality factor XNOR gate using quantum-dot semiconductor optical amplifiers at 1 Tb/s

    Energy Technology Data Exchange (ETDEWEB)

    Kotd, Amer, E-mail: amer_22003@yahoo.com, E-mail: kotb@phys.uconn.edu [Department of Physics, Faculty of Science, Fayoum University, Fayoum, (Egypt)

    2015-06-15

    The modeling of all-optical logic XNOR gate is realized by a series combination of XOR and INVERT gates. This Boolean function is simulated by using Mach-Zehnder interferometers (MZIs) utilizing quantum-dots semiconductor optical amplifiers (QDs-SOAs). The study is carried out when the effect of amplified spontaneous emission (ASE) is included. The dependence of the output quality factor (Q-factor) on signals and QDs-SOAs' parameters is also investigated and discussed. The simulation is conducted under a repetition rate of ∼1 Tb/s. (author)

  5. Emission of OAM entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion

    CERN Document Server

    Javůrek, D; Peřina, J

    2014-01-01

    We suggest the generation of photon pairs in a thermally induced nonlinear periodically-poled silica fiber by spontaneous parametric down-conversion. Photons are generated directly in eigenstates of optical angular momentum. Photons in a pair can be entangled in these states as well as in frequencies. We identify suitable spatial and polarization modes giving an efficient nonlinear interaction. By changing the pump field properties both narrow- and broad-band down-converted fields can be obtained.

  6. Efficient ASE control in cryogenic gas cooled Yb:YAG multislab amplifiers with Cr4+:YAG interlayers

    Science.gov (United States)

    Xiao, Kaibo; Yuan, Xiaodong; Yan, Xiongwei; Li, Min; Jiang, Xinying; Wang, Zhenguo; Li, Mingzhong; Zheng, Wanguo; Zheng, Jiangang

    2016-03-01

    A novel approach based on Cr4+:YAG interlayers to break the transmission paths of amplified spontaneous emission (ASE) in a cryogenic gas cooled Yb:YAG multislab amplifier geometry was presented for the suppression of ASE in the power scaling of high energy, high average power laser systems. The benefits of Cr4+:YAG interlayers for the overall performance of an amplifier were illustrated with respect to energy storage capacity, heat generation and amplification of the seed pulses based on the theory of quasi-three-level Yb3+ ions and Cr4+:YAG saturable absorption, the Monte Carlo and ray-tracing methods. For the amplifier with optimized Cr4+:YAG interlayers, it was found that the energy storage efficiency was increased from 39.12% to 47.38% in comparison with the amplifier without interlayers. The maximum output energy of 1119.53 J with an optical-to-optical efficiency of 28.91% in the amplifier with interlayers was obtained, while it reduced to 810.61 J with an optical-to-optical efficiency of 20.94% in the amplifier without interlayers. To our knowledge, this is the first quantitative characterization of the performance of a cryogenic gas cooled Yb:YAG multislab amplifier with Cr4+:YAG interlayers.

  7. Fully Coherent X-ray Pulses from a Regenerative Amplifier Free Electron Laser

    International Nuclear Information System (INIS)

    We propose and analyze a novel regenerative amplifier free electron laser (FEL) to produce fully coherent x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches not only amplifies the radiation intensity but also broadens its spectrum, allowing for effective transmission of the x-rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about two to three orders of magnitude higher than that from a single-pass SASE FEL

  8. Fully Coherent X-Ray Pulses from a Regenerative-Amplifier Free-Electron Laser

    International Nuclear Information System (INIS)

    We propose and analyze a regenerative-amplifier free-electron laser (FEL) to produce fully coherent, hard x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches regeneratively amplifies the radiation intensity and broadens its spectrum, allowing for effective transmission of the x rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about 2 to 3 orders of magnitude higher than that from a single-pass SASE FEL

  9. Modeling of Mid-IR Amplifier Based on an Erbium-Doped Chalcogenide Microsphere

    Directory of Open Access Journals (Sweden)

    P. Bia

    2012-01-01

    Full Text Available An optical amplifier based on a tapered fiber and an Er3+-doped chalcogenide microsphere is designed and optimized. A dedicated 3D numerical model, which exploits the coupled mode theory and the rate equations, is used. The main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions have been considered. Both the pump and signal beams are efficiently injected and obtained by a suitable design of the taper angle and the fiber-microsphere gap. Moreover, a good overlapping between the optical signals and the rare-earth-doped region is also obtained. In order to evaluate the amplifier performance in reduced computational time, the doped area is partitioned in sectors. The obtained simulation results highlight that a high-efficiency midinfrared amplification can be obtained by using a quite small microsphere.

  10. Generation of spectrally-stable continuous-wave emission and ns pulses at 800 nm and 975 nm with a peak power of 4 W using a distributed Bragg reflector laser and a ridge-waveguide power amplifier

    Science.gov (United States)

    Klehr, A.; Wenzel, H.; Fricke, J.; Bugge, F.; Liero, A.; Hoffmann, Th.; Erbert, G.; Tränkle, G.

    2015-03-01

    Semiconductor based sources which emit high-power spectrally stable nearly diffraction-limited optical pulses in the nanosecond range are ideally suited for a lot of applications, such as free-space communications, metrology, material processing, seed lasers for fiber or solid state lasers, spectroscopy, LIDAR and frequency doubling. Detailed experimental investigations of 975 nm and 800 nm diode lasers based on master oscillator power amplifier (MOPA) light sources are presented. The MOPA systems consist of distributed Bragg reflector lasers (DBR) as master oscillators driven by a constant current and ridge waveguide power amplifiers which can be driven DC and by current pulses. In pulse regime the amplifiers modulated with rectangular current pulses of about 5 ns width and a repetition frequency of 200 kHz act as optical gates, converting the continuous wave (CW) input beam emitted by the DBR lasers into a train of short optical pulses which are amplified. With these experimental MOPA arrangements no relaxation oscillations in the pulse power occur. With a seed power of about 5 mW at a wavelength of 973 nm output powers behind the amplifier of about 1 W under DC injection and 4 W under pulsed operation, corresponding to amplification factors of 200 (amplifier gain 23 dB) and 800 (gain 29 dB) respectively, are reached. At 800 nm a CW power of 1 W is obtained for a seed power of 40 mW. The optical spectra of the emission of the amplifiers exhibit a single peak at a constant wavelength with a line width 50 dB. The output beams are nearly diffraction limited with beam propagation ratios M2lat ~ 1.1 and M2ver ~ 1.2 up to 4 W pulse power.

  11. Spontaneous Breaking of Spatial and Spin Symmetry in Spinor Condensates

    DEFF Research Database (Denmark)

    Scherer, M.; Lücke, B.; Gebreyesus, G.;

    2010-01-01

    Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified c...

  12. Kilowatt high-efficiency narrow-linewidth monolithic fiber amplifier operating at 1034 nm

    Science.gov (United States)

    Naderi, Nader A.; Flores, Angel; Anderson, Brian M.; Rowland, Ken; Dajani, Iyad

    2016-03-01

    Power scaling investigation of a narrow-linewidth, Ytterbium-doped all-fiber amplifier operating at 1034 nm is presented. Nonlinear stimulated Brillouin scattering (SBS) effects were suppressed through the utilization of an external phase modulation technique. Here, the power amplifier was seeded with a spectrally broadened master oscillator and the results were compared using both pseudo-random bit sequence (PRBS) and white noise source (WNS) phase modulation formats. By utilizing an optical band pass filter as well as optimizing the length of fiber used in the pre-amplifier stages, we were able to appreciably suppress unwanted amplified spontaneous emission (ASE). Notably, through PRBS phase modulation, greater than two-fold enhancement in threshold power was achieved when compared to the WNS modulated case. Consequently, by further optimizing both the power amplifier length and PRBS pattern at a clock rate of 3.5 GHz, we demonstrated 1 kilowatt of power with a slope efficiency of 81% and an overall ASE content of less than 1%. Beam quality measurements at 1 kilowatt provided near diffraction-limited operation (M2 knowledge, the power scaling results achieved in this work represent the highest power reported for a spectrally narrow all-fiber amplifier operating at < 1040 nm in Yb-doped silica-based fiber.

  13. Combined planar imaging of schlieren photography with OH-LIPF and spontaneous OH-emission in a 2-D valveless pulse combustor

    Energy Technology Data Exchange (ETDEWEB)

    Ishino, Yojiro; Hasegawa, Tatsuya; Yamaguchi, Shigeki; Ohiwa, Norio

    1999-07-01

    Using a novel optical system, simultaneous imaging of schlieren photography and laser induced predissociation fluorescence of OH radicals (OH-LIPF) have been carried out to examine combustion processes and flame structure in a two-dimensional valveless pulse combustor. Simultaneous imaging of schlieren photographs and spontaneous OH-emission have also been made, in order to obtain information on the behavior of the flame front during a cycle of pulsation. The pulse combustor used in this experiment consists of a combustion chamber of a volume of 125 cm{sup 3} and a tailpipe of a length of 976 mm, which is followed by an automobile muffler. The fuel used is commercial grade gaseous propane.

  14. DIAMOND AMPLIFIED PHOTOCATHODES.

    Energy Technology Data Exchange (ETDEWEB)

    SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

    2007-11-26

    High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

  15. Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

    International Nuclear Information System (INIS)

    We recently reported an experiment which focused on demonstrating the macro-coherent amplification mechanism. This mechanism, which was proposed for neutrino mass measurements, indicates that a multi-particle emission rate should be amplified by coherence in a suitable medium. Using a para-hydrogen molecule gas target and the adiabatic Raman excitation method, we observed that the two photon emission rate was amplified by a factor of more than 1015 from the spontaneous emission rate. This paper briefly summarizes the previous experimental result and presents the current status and the future prospect

  16. Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Takahiko, E-mail: masuda@okayama-u.ac.jp; Hara, Hideaki; Miyamoto, Yuki [Okayama University, Research Core for Extreme Quantum World (Japan); Kuma, Susumu [Atomic, Molecular and Optical Physics Laboratory, RIKEN (Japan); Nakano, Itsuo [Okayama University, Research Core for Extreme Quantum World (Japan); Ohae, Chiaki [University of Electro-Communications, Department of Engineering Science (Japan); Sasao, Noboru [Okayama University, Research Core for Extreme Quantum World (Japan); Tanaka, Minoru [Osaka University, Department of Physics (Japan); Uetake, Satoshi [Okayama University, Research Center of Quantum Universe (Japan); Yoshimi, Akihiro; Yoshimura, Koji [Okayama University, Research Core for Extreme Quantum World (Japan); Yoshimura, Motohiko [Okayama University, Research Center of Quantum Universe (Japan)

    2015-11-15

    We recently reported an experiment which focused on demonstrating the macro-coherent amplification mechanism. This mechanism, which was proposed for neutrino mass measurements, indicates that a multi-particle emission rate should be amplified by coherence in a suitable medium. Using a para-hydrogen molecule gas target and the adiabatic Raman excitation method, we observed that the two photon emission rate was amplified by a factor of more than 10{sup 15} from the spontaneous emission rate. This paper briefly summarizes the previous experimental result and presents the current status and the future prospect.

  17. Stark interaction of identical particles with the vacuum electromagnetic field as quantum Poisson process suppressing collective spontaneous emission

    International Nuclear Information System (INIS)

    The effective Hamiltonian describing resonant interaction of an ensemble of identical quantum particles with a photon-free vacuum electromagnetic field has been obtained with allowance for terms of second order in the coupling constant (the Stark interaction) by means of the perturbation theory on the basis of the unitary transformation of the system quantum state. It has been shown that in the Markov approximation the effective Hamiltonian terms of first order in the coupling constant are represented by the quantum Wiener process, whereas terms of second order are expressed by the quantum Poisson process. During the course of the investigation, it was established that the Stark interaction played a significant role in the ensemble dynamics, thus influencing the collective spontaneous decay of the ensemble of an appreciably high number of identical particles. Fundamental effects have been discovered, i.e., the excitation conservation in a sufficiently dense ensemble of identical particles and superradiance suppression in the collective decaying process of an excited ensemble with a determined number of particles.

  18. Spontaneous organisation of ZnS nanoparticles into monocrystalline nanorods with highly enhanced dopant-related emission

    Science.gov (United States)

    Manzoor, K.; Aditya, V.; Vadera, S. R.; Kumar, N.; Kutty, T. R. N.

    2005-07-01

    A natural self-assembly process of semiconductor nanoparticles leading to the formation of doped, monocrystalline nanorods with highly enhanced dopant-related luminescence properties is reported. ˜4 nm sized, polycrystalline ZnS nanoparticles of zinc-blende (cubic) structure, doped with Cu+-Al3+ or Mn2+ have been aggregated in the aqueous solution and grown into nanorods of length ˜400 nm and aspect ratio ˜12. Transmission electron microscopic (TEM) images indicate crystal growth mechanisms involving both Ostwald-ripening and particle-to-particle oriented-attachment. Sulphur sulphur catenation is proposed for the covalent-linkage between the attached particles. The nanorods exhibit self-assembly mediated quenching of the lattice defect-related emission accompanied by multifold enhancement in the dopant-related emission. This study demonstrates that the collective behavior of an ensemble of bare nanoparticles, under natural conditions, can lead to the formation of functionalized (doped) nanorods with enhanced luminescence properties.

  19. Spontaneous pneumothorax

    Directory of Open Access Journals (Sweden)

    Davari R

    1996-07-01

    Full Text Available A case with bilateral spontaneous pneumothorax was presented. Etiology, mechanism, and treatment were discussed on the review of literature. Spontaneous Pneumothorax is a clinical entity resulting from a sudden non traumatic rupture of the lung. Biach reported in 1880 that 78% of 916 patients with spontaneous pneumothorax had tuberculosis. Kjergaard emphasized 1932 the primary importance of subpleural bleb disease. Currently the clinical spectrum of spontaneous pneumothorax seems to have entered a third era with the recognition of the interstitial lung disease and AIDS as a significant etiology. Standard treatment is including: observation, thoracocentesis, tube thoracostomy. Chemical pleurodesis, bullectomy or wedge resection of lung with pleural abrasion and occasionally pleurectomy. Little information has been reported regarding the efficacy of such treatment in spontaneous pneumothorax secondary to non bleb disease

  20. Detecção de emissão espontânea de luz em ensaios de colimetria aplicados ao monitoramento de efluentes sanitários Spontaneous light emission in coliforms test applied to wastewater monitoring

    Directory of Open Access Journals (Sweden)

    Samuel Ricardo dos Santos

    2011-03-01

    Full Text Available No presente trabalho avaliou-se o potencial do emprego da técnica biofotônica ao monitoramento da qualidade microbiológica de efluentes sanitários, por meio da detecção de emissão ultrafraca de luz em testes envolvendo bactéria do grupo coliforme. Foram acompanhados os padrões de emissão de luz em câmara escura com o uso de efluente doméstico, antes e após tratamento, incubados em meio nutritivo à base de lactose e lauril triptose. O controle foi efetuado com o uso de cepa de Escherichia coli (ATCC 25.922, tendo seu crescimento sido monitorado por emissão de luz em câmara escura com fotomultiplicador acoplado. Os dados demonstraram que o monitoramento microbiológico pode ser efetuado por meio técnica biofotônica, podendo ser aplicado, com respostas rápidas, ao monitoramento microbiológico de efluentes, por meio de testes envolvendo coliformes.The spontaneous light emission of living systems emerge as a promising methodology that applied to microbiological in monitoring water can lead to short-term analysis. The present study evaluated the potential of biophoton measurements applied to wastewater monitoring by using ultraweak light emission in coliform tests. The procedure is based on photon-counting measurements inside a dark-chamber, of wastewater samples, before and after treatment, inoculated in nutrient presence/absence medium (lactose and lauryl triptose broth. Strain of Escherichia coli (ATCC 25,922 was used in control tests by monitoring the light emission inside a dark-chamber with an acoplade photomultiplier. The data showed that microbiological monitoring can be done by photon-counting in real-time applied to microbiological wastewater monitoring using coliform test.

  1. Low cost instrumentation amplifier

    Science.gov (United States)

    Sturman, J. C.

    1974-01-01

    Amplifier can be used for many applications requiring high input impedance and common mode rejection, low drift, and gain accuracy on order of one percent. Performance of inexpensive amplifier approaches that of some commercial instrumentation amplifiers in many specifications.

  2. Theoretical analysis of an end-pumped Yb:YAG active mirror thin-disk amplifier with a longitudinal doping concentration gradient.

    Science.gov (United States)

    Bourdet, Gilbert L; Gouedard, Claude

    2014-11-01

    In this paper, we present a theoretical derivation of the amplification in a longitudinally pumped amplifier with a doping gradient concentration optimized for obtaining a constant longitudinal gain. This technique makes it possible to reduce both the effect of the amplification of the spontaneous emission (ASE) and the temperature gradient. We will express the longitudinal concentration profile as a function of the amplifier parameters and the launched pump intensity. Our computations show the limits of such a technique for controlling the ASE. We will also make a proposal for a technique to achieve such a controlled concentration profile. PMID:25402924

  3. The closed orbit theoretical calculation of the spontaneous emission rate of atom near the interface%原子在界面附近自发辐射率的闭合轨道理论计算

    Institute of Scientific and Technical Information of China (English)

    王丽林; 徐强; 隗莲

    2013-01-01

    利用闭合轨道理论,对原子在界面附近的自发辐射率的计算公式进行了推导,并对界面附近原子自发辐射率的多周期振荡现象进行了系统的研究。首先,根据光子的闭合轨道理论,把原子的自发辐射用经典的偶极天线辐射来模拟,推导出原子在一个金属界面旁的自发辐射率的计算公式,然后再推广到两个金属界面旁的原子自发辐射情况,并对原子自发辐射率的多周期振荡进行了分析。%We derived the formula of the spontaneous emission rate of atoms near the interfaces and discussed the multi-periodic oscillating phenomenon of the atoms near the interfaces .First of all ,according to the photon closed-orbit theory ,we simulated the spontaneous emission of atom near interface as the radiation of the classic dipole antenna ,then we derived the calculation for-mula of the spontaneous emission of atom near a metal surface .Next ,we developed this case to the spontaneous emission of atom near two metal surfaces ,and analyzed the multi-periodic oscil-lating phenomenon appeared in the spontaneous emission rate of atom near two metal surfaces .

  4. Spontaneous photon emission from a non-relativistic free charged particle in collapse models: A case study

    International Nuclear Information System (INIS)

    We study the photon emission rate of a non-relativistic charged particle interacting with an external classical noise through its position. Both the particle and the electromagnetic field are quantized. Under only the dipole approximation, the equations of motion can be solved exactly for a free particle, or a particle bounded by an harmonic potential. The physical quantity we will be interested in is the spectrum of the radiation emitted by the particle, due to the interaction with the noise. We will highlight several properties of the spectrum and clarify some issues appearing in the literature, regarding the exact mathematical formula of a spectrum for a free particle.

  5. Spontaneous Fission

    Science.gov (United States)

    Segre, Emilio

    1950-11-22

    The first attempt to discover spontaneous fission in uranium was made by [Willard] Libby, who, however, failed to detect it on account of the smallness of effect. In 1940, [K. A.] Petrzhak and [G. N.] Flerov, using more sensitive methods, discovered spontaneous fission in uranium and gave some rough estimates of the spontaneous fission decay constant of this substance. Subsequently, extensive experimental work on the subject has been performed by several investigators and will be quoted in the various sections. [N.] Bohr and [A.] Wheeler have given a theory of the effect based on the usual ideas of penetration of potential barriers. On this project spontaneous fission has been studied for the past several years in an effort to obtain a complete picture of the phenomenon. For this purpose the spontaneous fission decay constants {lambda} have been measured for separated isotopes of the heavy elements wherever possible. Moreover, the number {nu} of neutrons emitted per fission has been measured wherever feasible, and other characteristics of the spontaneous fission process have been studied. This report summarizes the spontaneous fission work done at Los Alamos up to January 1, 1945. A chronological record of the work is contained in the Los Alamos monthly reports.

  6. Analysis of strain effects on the dynamic spectra of a quantum well semiconductor optical amplifier using quantum well transmission line modelling method

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H.

    2016-04-01

    This paper studies the strain (i.e. compressive (CS) and tensile (TS)) effects on the dynamic spectra of an amplified femtosecond pulse in a quantum well semiconductor optical amplifier (QW-SOA) using quantum well transmission line modelling (QW-TLM) method. Based on the analysis of band structure, the gain spectrum as well as the spontaneous spectrum of quantum well (QW) in the CS, unstrained (US) and TS are investigated using QW-TLM and it was found that in the CS QW, the magnitude ratio of the gain spectrum and the spontaneous emission spectrum is the largest. Furthermore, QW-TLM is adopted to investigate the dynamic spectral evolution of femtosecond pulse amplification in QW-SOAs and it was found that as the femtosecond pulse approaches the amplifier output, the centre frequency of the amplified femtosecond pulse spectra decreases and its bandwidth decreases. The output spectra of the amplified femtosecond pulse in QW amplifiers under the CS, US and TS cases are compared and the simulation results show that in a CS QW-SOA the spectral shape exhibits the largest magnitude and the smallest fluctuation due to the largest gain and the largest ratio between the gain and noise.

  7. Thermal effects in Yb:YAG single-crystal thin-rod amplifier.

    Science.gov (United States)

    Kuznetsov, Ivan; Mukhin, Ivan; Vadimova, Olga; Palashov, Oleg; Ueda, Ken-Ichi

    2015-09-01

    This work presents a new design for the laser gain module based on a ytterbium-doped yttrium aluminum garnet (Yb:YAG) single-crystal thin rod. Thermal effects (temperature, phase, and polarization distortion of laser radiation) and small signal gain are investigated both experimentally and theoretically. We then analyzed the influence of thermal effects and amplified spontaneous emission on the power scaling of the laser based on the gain module. A small signal gain as high as 3.3 per pass was experimentally achieved. PMID:26368900

  8. Spontaneous fission

    International Nuclear Information System (INIS)

    Recent experimental results for spontaneous fission half-lives and fission fragment mass and kinetic-energy distributions and other properties of the fragments are reviewed and compared with recent theoretical models. The experimental data lend support to the existence of the predicted deformed shells near Z = 108 and N = 162. Prospects for extending detailed studies of spontaneous fission properties to elements beyond hahnium (element 105) are considered. (orig.)

  9. Amplifier Noise Based Optical Steganography with Coherent Detection

    Science.gov (United States)

    Wu, Ben; Chang, Matthew P.; Caldwell, Naomi R.; Caldwell, Myles E.; Prucnal, Paul R.

    2014-12-01

    We summarize the principle and experimental setup of optical steganography based on amplified spontaneous emission (ASE) noise. Using ASE noise as the signal carrier, optical steganography effectively hides a stealth channel in both the time domain and the frequency domain. Coherent detection is used at the receiver of the stealth channel. Because ASE noise has short coherence length and random phase, it only interferes with itself within a very short range. Coherent detection requires the stealth transmitter and stealth receiver to precisely match the optical delay,which generates a large key space for the stealth channel. Several methods to further improve optical steganography, signal to noise ratio, compatibility with the public channel, and applications of the stealth channel are also summarized in this review paper.

  10. Gain ranging amplifier

    International Nuclear Information System (INIS)

    A gain ranging amplifier system is provided for use in the acquisition of data. Voltage offset compensation is utilized to correct errors in the gain ranging amplifier system caused by thermal drift and temperature dependent voltage offsets, both of which are associated with amplifiers in the gain ranging amplifier system

  11. Interactions of low-power photons with natural opals—PBG materials, photonic control, natural metamaterials, spontaneous laser emissions, and band-gap boundary responses

    International Nuclear Information System (INIS)

    Four views of each of the opal research specimens in white light (for in-article or cover), in the same order as the specimens depicted in Fig. 3 of the main manuscript. A.On the left: 1.5 carat oval cabochon precious fire opal. B.In the center: 2.5 carats faceted fancy shield precious fire contra luz with mild adularescence. C.On the right: 5.0 carats round cabochon precious crystal opal with blue adularescence. Highlights: ► Emission of micro-lasers from microspheroid cluster boundary zones (quantum dots). ► Lasers illuminated or fluoresced the intra-opal structures of microspheroid photonic glass clusters. ► Microspheroid boundaries are durable to low power light sources. ► Display of previously unknown low power photonic optic properties. ► The research specimens are natural metamaterials. - Abstract: One overall goal of this research was to examine types of naturally-occurring opals that exhibit photonic control to learn about previously-unknown properties of naturally occurring photonic control that may be developed for broader applications. Three different photon sources were applied consecutively to three different types of natural, flawless, gem-quality precious opals. Two photon sources were lasers (green and red) and one was simulated daylight tungsten white. As each type of precious opal was exposed to each of the photon sources, the respective refractions, reflections, and transmissions were studied. This research is the first to show that applying various pleochroic and laser photon sources to these types of opals revealed significant information regarding naturally occurring photonic control, metamaterials, spontaneous laser emissions, and microspheroid cluster (inter-PBG zone) boundary effects. Plus, minimizing ambient light and the use of low power photon sources were critical to observing the properties regarding this photonic materials research. This research yielded information applicable to the development of materials to advance

  12. Amplified Quantum Transforms

    OpenAIRE

    Cornwell, David

    2014-01-01

    In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. First, we provide a brief history of quantum mechanics and quantum computing. Second, we examine the Amplified-QFT in detail and compare it against the Quantum Fourier Transform (QFT) and Quantum Hidden Subgroup (QHS) algorithms for solving the Local Period Problem. We calculate the probabiliti...

  13. Spontaneous pneumothorax

    OpenAIRE

    Wakai, Abel P

    2008-01-01

    Spontaneous pneumothorax is defined as air entering the pleural space without any provoking factor, such as trauma, surgery, or diagnostic intervention. Incidence is 24/100,000 a year in men, and 10/100,000 in women in England and Wales, and the major contributing factor is smoking, which increases the likelihood by 22 times in men and by 8 times in women.While death from spontaneous pneumothorax is rare, rates of recurrence are high, with one study of men in the US finding a total recurre...

  14. Spontaneous pneumothorax

    OpenAIRE

    Wakai, Abel P

    2011-01-01

    Spontaneous pneumothorax is defined as air entering the pleural space without any provoking factor, such as trauma, surgery, or diagnostic intervention. Incidence is 24/100,000 a year in men, and 10/100,000 a year in women in England and Wales, and the major contributing factor is smoking, which increases the likelihood by 22 times in men and by 8 times in women.While death from spontaneous pneumothorax is rare, rates of recurrence are high, with one study of men in the US finding a total ...

  15. Blue laser emission by intracavity second harmonic generation in Nd:ASL pumped by a tapered amplifier laser diode stabilized by a volume Bragg grating

    OpenAIRE

    Pabœuf, David; Lucas-Leclin, Gaëlle; Georges, Patrick; Sumpf, Bernd; Ebert, Götz; Varona, Cyrille; Loiseau, Pascal; Aka, Gérard; Ferrand, Bernard

    2008-01-01

    International audience We present the diode pumping of a Nd:ASL (Sr1-xLax-yNdyMgxAl12-x O19) crystal for second harmonic generation at 453 nm. We have developed a high-brightness pump source based on a tapered amplifier in an extended cavity with a volume Bragg grating for wavelength stabilization. A pump brightness of 110 MW.cm-2sr-1 is obtained with a linewidth lower than 80 pm at 798 nm. This laser source is used to pump a Nd:ASL crystal to obtain 300 mW at 906 nm and 53 mW at 453 nm by...

  16. Portable musical instrument amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Christian, David E. (Danbury, CT)

    1990-07-24

    The present invention relates to a musical instrument amplifier which is particularly useful for electric guitars. The amplifier has a rigid body for housing both the electronic system for amplifying and processing signals from the guitar and the system's power supply. An input plug connected to and projecting from the body is electrically coupled to the signal amplifying and processing system. When the plug is inserted into an output jack for an electric guitar, the body is rigidly carried by the guitar, and the guitar is operatively connected to the electrical amplifying and signal processing system without use of a loose interconnection cable. The amplifier is provided with an output jack, into which headphones are plugged to receive amplified signals from the guitar. By eliminating the conventional interconnection cable, the amplifier of the present invention can be used by musicians with increased flexibility and greater freedom of movement.

  17. Amplifier for nuclear spectrometry

    International Nuclear Information System (INIS)

    The spectroscopy amplifier model AE-020 is designed to adjust suitable the pulses coming from nuclear radiation detectors. Due to is capacity and specifications, the amplifier can be used together with high and medium resolution spectroscopy system

  18. High voltage distributed amplifier

    Science.gov (United States)

    Willems, D.; Bahl, I.; Wirsing, K.

    1991-12-01

    A high-voltage distributed amplifier implemented in GaAs MMIC technology has demonstrated good circuit performance over at least two octave bandwidth. This technique allows for very broadband amplifier operation with good efficiency in satellite, active-aperture radar, and battery-powered systems. Also, by increasing the number of FETs, the amplifier can be designed to match different voltage rails. The circuit does require a small amount of additional chip size over conventional distributed amplifiers but does not require power dividers or additional matching networks. This circuit configuration should find great use in broadband power amplifier design.

  19. Generation of 130 W narrow-linewidth high-peak-power picosecond pulses directly from a compact Yb-doped single-stage fiber amplifier

    Science.gov (United States)

    Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Wang, Lei; Zhang, Ling; Lin, Xuechun

    2015-09-01

    We report a compact, 130-W single-stage master oscillator power amplifier with a high peak power of 51.3 kW and a narrow spectral linewidth of 0.1 nm. The seed source is a single-mode, passively mode-locked solid-state laser at 1064 nm with an average power of 2 W. At a repetition rate of 73.5 MHz, the pulse duration is 30 ps. After amplification, it stretches to 34.5 ps. The experiment enables the optical-to-optical conversion efficiency to reach 75%. To the best of our knowledge, this is the first report of such a high-power, narrow spectral linewidth, high peak power picosecond-pulse fiber amplifier based on a continuous-wave, mode-locked solid-state seeding laser. No amplified spontaneous emission and stimulated Raman scattering were observed when the pump was increased.

  20. Quantum cloning with an optical fiber amplifier

    OpenAIRE

    Fasel, Sylvain; Gisin, Nicolas; Ribordy, Grégoire; Scarani, Valerio; Zbinden, Hugo

    2002-01-01

    It has been shown theoretically that a light amplifier working on the physical principle of stimulated emission should achieve optimal quantum cloning of the polarization state of light. We demonstrate close-to-optimal universal quantum cloning of polarization in a standard fiber amplifier for telecom wavelengths. For cloning 1 --> 2 we find a fidelity of 0.82, the optimal value being 5/6 = 0.83.

  1. Optimal design of a high-power picosecond laser system using a dual-stage ytterbium-doped fibre amplifier

    Science.gov (United States)

    You, Yi-Jing; Lin, Chih-Hsuan; Zaytsev, Alexey; Tsai, Feng-Hua; Wang, Chi-Luen; Pan, Ci-Ling

    2013-07-01

    An average power as high as 60 W with 73 W of pumping was achieved for an ytterbium-doped fibre-based dual-stage amplifier (MOFA) system seeded by a diode-pumped solid-state (DPSS) laser. The corresponding optical conversion efficiency is 80%. The laser system generates a steady pulse train with a pulse width of 11 ps at a repetition rate of 250 MHz or a peak power of 21.8 kW. Moreover, the output beam quality M2 ≈ 1.6. The length and pumping power for the Yb-doped fibres were optimized to suppress stimulated Raman scattering (SRS) and amplified spontaneous emission (ASE) while maintaining desirable output characteristics.

  2. Performance of All-Optical XNOR Gate Based on Two-Photon Absorption in Semiconductor Optical Amplifiers

    Directory of Open Access Journals (Sweden)

    Amer Kotb

    2014-01-01

    Full Text Available All-optical logic XNOR gate is realized by a series combination of XOR and INVERT gates. This Boolean function is realized by using Mach-Zehnder interferometers (MZIs and exploiting the nonlinear effect of two-photon absorption (TPA in semiconductor optical amplifiers (SOAs. The employed model takes into account the impact of amplified spontaneous emission (ASE, input pulse energy, pulsewidth, SOAs carrier lifetime, and linewidth enhancement factor (α-factor on the gate’s output quality factor (Q-factor. The outcome of this study shows that the all-optical XNOR gate is indeed feasible with the proposed scheme at 250 Gb/s with both logical correctness and acceptable quality.

  3. Optimal design of a high-power picosecond laser system using a dual-stage ytterbium-doped fibre amplifier

    International Nuclear Information System (INIS)

    An average power as high as 60 W with 73 W of pumping was achieved for an ytterbium-doped fibre-based dual-stage amplifier (MOFA) system seeded by a diode-pumped solid-state (DPSS) laser. The corresponding optical conversion efficiency is 80%. The laser system generates a steady pulse train with a pulse width of 11 ps at a repetition rate of 250 MHz or a peak power of 21.8 kW. Moreover, the output beam quality M2 ≈ 1.6. The length and pumping power for the Yb-doped fibres were optimized to suppress stimulated Raman scattering (SRS) and amplified spontaneous emission (ASE) while maintaining desirable output characteristics. (paper)

  4. Spontaneous fission properties and lifetime systematics

    International Nuclear Information System (INIS)

    Half-lives for spontaneous fission of nuclides with even and odd numbers of particles are compared with recent theoretical calculations. A summary of odd particle hindrance factors is given. The most recent measurements of kinetic-energy and mass distributions and neutron emission for spontaneous fission of the heaviest nuclides are summarized and discussed. 51 refs., 9 figs

  5. Interference of spontaneously emitted photons

    CERN Document Server

    Beige, A; Pachos, J; Beige, Almut; Schoen, Christian; Pachos, Jiannis

    2002-01-01

    We discuss an experimental setup where two laser-driven atoms spontaneously emit photons and every photon causes a ``click'' at a point on a screen. By deriving the probability density for an emission into a certain direction from basic quantum mechanical principles we predict a spatial interference pattern. Similarities and differences with the classical double-slit experiment are discussed.

  6. Interference of spontaneously emitted photons

    OpenAIRE

    Beige, Almut; Schoen, Christian; Pachos, Jiannis

    2001-01-01

    We discuss an experimental setup where two laser-driven atoms spontaneously emit photons and every photon causes a ``click'' at a point on a screen. By deriving the probability density for an emission into a certain direction from basic quantum mechanical principles we predict a spatial interference pattern. Similarities and differences with the classical double-slit experiment are discussed.

  7. RF Power Amplifier Analysis

    OpenAIRE

    M. Lokay; K. Pelikan

    1993-01-01

    The special program is presented for the demonstration of RF power transistor amplifiers for the purposes of the high-school education in courses of radio transmitters. The program is written in Turbo Pascal 6. 0 and enables to study the waveforms in selected points of the amplifier and to draw the trajectories of the working point in a plot of output transistor characteristics.

  8. Amplifier improvement circuit

    Science.gov (United States)

    Sturman, J.

    1968-01-01

    Stable input stage was designed for the use with a integrated circuit operational amplifier to provide improved performance as an instrumentation-type amplifier. The circuit provides high input impedance, stable gain, good common mode rejection, very low drift, and low output impedance.

  9. Amplification of picosecond pulse by electron-beam pumped KrF laser amplifiers. Denshi beam reiki KrF laser zofukuki ni yoru piko byo pulse no zofuku

    Energy Technology Data Exchange (ETDEWEB)

    Okuda, I.; Tomie, T.; Owadano, Y.; Yano, M. (Electrotechnical Laboratory, Tsukuba (Japan))

    1991-08-20

    Experiments on the amplification of a picosecond pulse by electron-beam pumped KrF laser amplifiers were carried out for the purpose of its application to the field such as excitation light source for soft X-ray laser which requires large energy besides peak power. The picosecond pulse was amplified by a discharge pumped KrF amplifier and two electron-beam pumped KrF amplifiers(at the middle stage and the final stage). The energy of 4J, which was the largest energy for short pulse excimer laser so far, was obtained by these devices. About 90% of the window area of the final amplifier with 29cm diameter was filled by the input beam, and energy density of the picosecond beam reached 3.9 times saturation energy density. Measured energy of amplified spontaneous emission(ASE) showed good agreement with the theoretically estimated value. Most of ASE was derived from the discharge pumped laser as the first amplifier. As for the focused power density, the power density ratio of the picosecond pulse to ASE was estimated to be as large as 10{sup 5}. 11 refs., 4 figs.

  10. Quantum and Raman Noise in a Depleted Fiber Optical Parametric Amplifier

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, Colin J.

    2013-01-01

    The noise properties of both phase-sensitive and phase-insensitive saturated parametric amplifiers are studied using a semi-classical approach. Vacuum fluctuations as well as spontaneous Raman scattering are included in the analysis....

  11. Semiconductor optical amplifiers

    CERN Document Server

    Dutta, Niloy K

    2013-01-01

    This invaluable look provides a comprehensive treatment of design and applications of semiconductor optical amplifiers (SOA). SOA is an important component for optical communication systems. It has applications as in-line amplifiers and as functional devices in evolving optical networks. The functional applications of SOAs were first studied in the early 1990's, since then the diversity and scope of such applications have been steadily growing. This is the second edition of a book on Semiconductor Optical Amplifiers first published in 2006 by the same authors. Several chapters and sections rep

  12. Polymer optical waveguide composed of europium-aluminum-acrylate composite core for compact optical amplifier and laser

    Science.gov (United States)

    Mitani, Marina; Yamashita, Kenichi; Fukui, Toshimi; Ishigure, Takaaki

    2015-02-01

    We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

  13. RF Power Amplifier Analysis

    Directory of Open Access Journals (Sweden)

    M. Lokay

    1993-04-01

    Full Text Available The special program is presented for the demonstration of RF power transistor amplifiers for the purposes of the high-school education in courses of radio transmitters. The program is written in Turbo Pascal 6. 0 and enables to study the waveforms in selected points of the amplifier and to draw the trajectories of the working point in a plot of output transistor characteristics.

  14. Charge-sensitive amplifier

    OpenAIRE

    Startsev V. I.; Yampolsky Ju. S.

    2008-01-01

    The authors consider design and circuit design techniques of reduction of the influence of the pyroelectric effect on operation of the charge sensitive amplifiers. The presented experimental results confirm the validity of the measures taken to reduce the impact of pyroelectric currents. Pyroelectric currents are caused by the influence of the temperature gradient on the piezoelectric sensor and on the output voltage of charge sensitive amplifiers.

  15. E-537 MWPC amplifier

    International Nuclear Information System (INIS)

    The design of a fast MWPC amplifier for the beam chambers and the absorber chamber is completed and all parts are on order. A prototype 16 channel board has been built and satisfactorily tested. Artwork is completed for the board and out to be photographed. The board fabrication contract has been let. Listed below is a summary of the amplifier characteristics as well as test results obtained with the prototype

  16. Electrospun Amplified Fiber Optics

    OpenAIRE

    Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

    2015-01-01

    A lot of research is focused on all-optical signal processing, aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for an efficient signal transmission. However, the complex fabrication methods, involving high-temperature processes performed in highly pure environment, slow down the fabrication and make amplified components expensive with respect to an ideal, ...

  17. Performance of the SASE amplifier of the TEU-FEL Project

    International Nuclear Information System (INIS)

    The free-electron laser of the TEU-FEL Project of the University of Twente will be driven by a photoinjector followed by a racetrack microtron. The injector, which is now under construction, will provide a very high-brightness electron beam with an energy of about 6 MeV. In Phase 1 of the Project, experiments are being planned in which this low energy beam from the injector will pass through an undulator and will generate radiation at a wavelength of about 200 μm via the process of Self-Amplified Spontaneous Emission (SASE). Numerical simulations of the performance of this source indicate that power levels of about 15 MW (averaged over a micropulse) can be obtained with a 1-m undulator. We present additional results derived from simulation studies of the performance of this device. 11 refs., 4 figs., 3 tabs

  18. Comment on "Effect of entanglement on the decay dynamics of a pair of H(2p) atoms due to spontaneous emission"

    OpenAIRE

    Sancho, Pedro; Plaja, Luis

    2011-01-01

    Tanabe et al (Phys. Rev. A {\\bf 82} 040101(R) 2010) have experimentally demonstrated that the emission properties of unstable atoms in entangled and product states are different. The authors define an apparent decay time as a fitting parameter which falls below the lifetime of the single atom for entangled pairs. We argue that their results about coincidence time spectra are correct, but those concerning lifetimes cannot be considered conclusive because they assume the emission of photons by ...

  19. FEL gain optimisation and spontaneous radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

    1995-12-31

    Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

  20. A micropower electrocardiogram amplifier.

    Science.gov (United States)

    Fay, L; Misra, V; Sarpeshkar, R

    2009-10-01

    We introduce an electrocardiogram (EKG) preamplifier with a power consumption of 2.8 muW, 8.1 muVrms input-referred noise, and a common-mode rejection ratio of 90 dB. Compared to previously reported work, this amplifier represents a significant reduction in power with little compromise in signal quality. The improvement in performance may be attributed to many optimizations throughout the design including the use of subthreshold transistor operation to improve noise efficiency, gain-setting capacitors versus resistors, half-rail operation wherever possible, optimal power allocations among amplifier blocks, and the sizing of devices to improve matching and reduce noise. We envision that the micropower amplifier can be used as part of a wireless EKG monitoring system powered by rectified radio-frequency energy or other forms of energy harvesting like body vibration and body heat. PMID:23853270

  1. A vircator amplifier

    International Nuclear Information System (INIS)

    A cavity vircator has demonstrated that formation of a virtual cathode in a cavity can improve microwave production efficiency and narrow the radiation bandwidth. When the virtual cathode radiates the microwave fields grow from noise. For each cavity, there is only one or a limited number of allowable modes for a given frequency. In this paper, a novel device - a vircator amplifier is described. The device consists of a relativistic magnetron and a cavity vircator with both devices powered by a 1 MeV, 3 Ω, 65 ns FWHM pulser. The idea is to inject a signal from the magnetron before and during virtual cathode formation in a cavity. The injected signal should lock the frequency and enhance electron bunching and therefore improve efficiency further. Experiments underway to evaluate the amplifier operating characteristics are discussed. The applicability of vircator amplifiers to the next generation of high-power microwave devices are addressed

  2. Effect of pulsed electric field on spontaneous photon emission of corn seedlings under osmotic stress%脉冲电场对渗透胁迫下玉米幼苗自发光子辐射的影响

    Institute of Scientific and Technical Information of China (English)

    习岗; 贺瑞瑞; 刘锴; 赵燕燕

    2015-01-01

    There are many complex physiological and biochemical reactions in the process of crop seed germination, so germinating seeds are very susceptible to environmental changes and have significant changes on the later growth. Using various physical methods to improve crops drought resistance has been one of the important research directions of modern agriculture, and the majority of studies have been focused on the high-voltage electrostatic field. Recent studies showed that the center frequency of corn cell potential fluctuations was in near 1 Hz, the cell potential coupling resonance could be occurred under the action of 1 Hz pulsed electric field, and some key physiological processes such as respiratory metabolism, photosynthesis, stomatal conductance and water uptake could be affected by the extremely low frequency pulsed electric field (ELF-PEF) with 1 Hz. Therefore, the effect of 1 Hz pulsed electric field on crop drought resistance could be greater than the electrostatic field. However, the reports about the effect of the ELF-PEF on crop drought resistance and its mechanism have been very little, and hence the corresponding researches need to be strengthened. Spontaneous photon emission is an important life information. Numerous studies have determined that the spontaneous photon emission from living cells is closely related to some important life processes such as cell metabolism, DNA synthesis, respiration and photosynthesis. The analysis of spontaneous photon emission from living cells could provide a non-invasive optical technology for the study of changes in the cell metabolism and the function of the state, and it has been widely used in the studies of plant reaction to pathogens, flooding, drought, salt stress, herbicides, UV radiation and so on. For the above reasons, after the germinating corn seeds were treated by 1 Hz ELF-PEF and the PEG-6000 solution was used to form physiological drought to corn seedlings, the growth of corn seedlings and spontaneous

  3. Modelling of Output Statistics of Single and ℳ-Mode Straight and Curved Er+:Ti:LiNbO Waveguide Amplifiers

    Directory of Open Access Journals (Sweden)

    Niculae N. Puscas

    2011-01-01

    Full Text Available A theoretical analysis of some statistical parameters which characterize the Er3+-doped Ti:LiNbO3 single and ℳ-mode straight and curved waveguides is presented in this paper. In the derivation and the evaluation of the spectral optical quality factor, the power spectral density, the Fano factor, the statistical fluctuation, and the spontaneous emission factor we used the small gain approximation, and the photon statistics master equation of the linear amplifier (considering that the photon number distribution is determined by the normalized mode intensity profiles which are not uniform in the transversal section of the waveguide, transposed to the case of straight and curved amplifiers. The simulation results show the evolution of the above-mentioned parameters under various pump regimes and waveguide lengths.

  4. Comment on "Effect of entanglement on the decay dynamics of a pair of H(2p) atoms due to spontaneous emission"

    CERN Document Server

    Sancho, Pedro

    2011-01-01

    Tanabe et al (Phys. Rev. A {\\bf 82} 040101(R) 2010) have experimentally demonstrated that the emission properties of unstable atoms in entangled and product states are different. The authors define an apparent decay time as a fitting parameter which falls below the lifetime of the single atom for entangled pairs. We argue that their results about coincidence time spectra are correct, but those concerning lifetimes cannot be considered conclusive because they assume the emission of photons by the two atoms to be independent processes, a doubtful hypothesis for entangled states. We suggest an improved evaluation of the lifetimes based on a rigorous approach, which demands some modifications of the experimental procedure.

  5. Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

    Energy Technology Data Exchange (ETDEWEB)

    Kazlauskas, Karolis, E-mail: karolis.kazlauskas@ff.vu.lt; Kreiza, Gediminas; Bobrovas, Olegas; Adomėnienė, Ona; Adomėnas, Povilas; Juršėnas, Saulius [Institute of Applied Research, Vilnius University, Saulėtekio 9-III, LT-10222 Vilnius (Lithuania); Jankauskas, Vygintas [Department of Solid State Electronics, Vilnius University, Saulėtekio 9-III, LT-10222 Vilnius (Lithuania)

    2015-07-27

    Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10{sup −2} cm{sup 2}/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 10{sup 9 }s{sup −1}) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm{sup 2}) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm{sup −1}) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.

  6. Emission spectra and stimulated emission characteristics of [N2]2--N2 molecular dimer

    Institute of Scientific and Technical Information of China (English)

    SHEN; Zuochun(申作春); LU; Jianye(鲁建业); Ajmal; H.; Hamdani; GAO; Huide(高惠德); MA; Zuguang(马祖光)

    2003-01-01

    It has been proved by ab initio calculation and theoretical analysis that there exist [N2]2--N2 molecular dimers with D2h symmetry group, and there also exists an electric dipole excimer-like transition a1B2g→a1B3u. The theoretical spectra accord with the experimental results for transition a1B2g→a1B3u. The stimulated emission characteristic of N2 molecular dimer was researched through the microwave excited highly pure nitrogen and the method of amplified spontaneous emission. The experimental results show that N2 molecular dimer has stimulated emission characteristics when the microwave power is more than 100 W and the N2 pressure is in the range from 260 Pa to 2200 Pa.

  7. Comment on ``Effect of entanglement on the decay dynamics of a pair of H(2p) atoms due to spontaneous emission''

    Science.gov (United States)

    Sancho, Pedro; Plaja, Luis

    2011-06-01

    T. Tanabe [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.040101 82, 040101(R) (2010)] have experimentally demonstrated that the emission properties of unstable atoms in entangled and product states are different. The authors define an apparent decay time as a fitting parameter which falls below the lifetime of the single atom for entangled pairs. We argue that their results about coincidence time spectra are correct, but those concerning lifetimes cannot be considered conclusive because they assume the emission of photons by the two atoms to be independent processes, a doubtful hypothesis for entangled states. We suggest an improved evaluation of the lifetimes based on a rigorous approach, which demands some modifications of the experimental procedure.

  8. Annual Change Detection by ASTER TIR Data and an Estimation of the Annual Coal Loss and CO2 Emission from Coal Seams Spontaneous Combustion

    OpenAIRE

    Xiaomin Du; Suping Peng; Haiyan Wang; Sergio Bernardes; Guang Yang; Zhipeng Li

    2014-01-01

    Coal fires, including both underground and coal waste pile fires, result in large losses of coal resources and emit considerable amounts of greenhouse gases. To estimate the annual intensity of greenhouse gas emissions and the loss of coal resources, estimating the annual loss from fire-influenced coal seams is a feasible approach. This study assumes that the primary cause of coal volume loss is subsurface coal seam fires. The main calculation process is divided into three modules: (1) Coal f...

  9. Measurement of excited oxygen (O2:[sup 1][Delta]g) concentration by spontaneous emission. Hakko kyodo ni yoru reiki sanso ([sup 1][Delta]g) nodo no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, S.; Hasegawa, Y.; Yamashita, I. (Mechanical Engineering Laboratory, Tsukuba (Japan))

    1993-11-25

    The concentration of excited oxygen ([sup 1][Delta]g), which was generated by microwave discharge in a pure oxygen flow, was measured from the intensity of spontaneous emission. The conversion factor to density was determined by spectroscopic analysis of the rotational structure and calibration of the emission intensity using a black-body furnace as light source. Consequently, a good agreement was found between the observed profiles and those calculated from spectroscopic data, and it was illustrated that the absolute concentration can be obtained by coupling band analysis and the calibration method. In addition, even when the concentration was low, it was shown that the excited oxygen concentration can be measured by considering the reflection at the cell wall. The excited oxygen concentration at the microwave discharge cavity was estimated to be around 1% under the pressure ranging from 0.5 torr to 2 torr. Furthermore, the comparison of the profiles calculated at different temperature provided that the band profile can be a good indicator of gas temperature when the signal-to-noise ratio is high. 9 refs., 10 figs., 2 tabs.

  10. Determination of the Primary Nuclear Charge of Fission Fragments from their Characteristic K-X-Ray Emission in Spontaneous Fission of Cf252

    International Nuclear Information System (INIS)

    The distribution of nuclear charge in the spontaneous fission of Cf252 has been determined directly by simultaneous measurement of the masses and characteristic K-X-ray energies associated with the primary fission products. The X-rays were detected by a thin Nal (Tl) crystal (or by an argon-filled proportional counter) in coincidence with a pair of solid-state detectors for the complementary fission fragments. Preliminary to the three-parameter study of the charge-mass distribution the gross characteristics of the K-X-rays were examined in some detail. The average yield of K-X-rays is 0.55 ± 0.1 pet fission (the heavy group accounting fot 70% of the total). From delayed-coincidence and fragment time-of-flight experiments it was.found that about 30% of the X-rays are emitted within 0.1 ns after fission, another 30% between 0.1 and 1 ns, 25% between 1 and 10 ns, the remainder appearing as two delayed components of equal intensity with half-lives of ∼30 ns and ∼100 ns. These characteristics indicate that the X-rays arise from internal conversion during de-excitation of the primary fission fragments, an interpretation supported by the observed yield 1 per fission) of 50 - 300 - keV electrons emitted within 2 ps of fission. In the three-parameter experiments the yield and energy of K-X-rays emitted in the first centimeter (ns) of fragment flight were determined as a function of fragment mass. The yield of K-X-rays per fragment is a pronounced saw-tooth function of mass, rising from p) function in better agreement with the empirical rule of equal charge displacement (ECD) than with other postulates for charge division in nuclear fission. (author)

  11. STABILIZED TRANSISTOR AMPLIFIER

    Science.gov (United States)

    Noe, J.B.

    1963-05-01

    A temperature stabilized transistor amplifier having a pair of transistors coupled in cascade relation that are capable of providing amplification through a temperature range of - 100 un. Concent 85% F to 400 un. Concent 85% F described. The stabilization of the amplifier is attained by coupling a feedback signal taken from the emitter of second transistor at a junction between two serially arranged biasing resistances in the circuit of the emitter of the second transistor to the base of the first transistor. Thus, a change in the emitter current of the second transistor is automatically corrected by the feedback adjustment of the base-emitter potential of the first transistor and by a corresponding change in the base-emitter potential of the second transistor. (AEC)

  12. Principal modes in fiber amplifiers

    CERN Document Server

    Fridman, Moti; Dubinskii, Mark; Friesem, Asher A; Davidson, Nir

    2010-01-01

    The dynamics of the state of polarization in single mode and multimode fiber amplifiers are presented. The experimental results reveal that although the state of polarizations at the output can vary over a large range when changing the temperatures of the fiber amplifiers, the variations are significantly reduced when resorting to the principal states of polarization in single mode fiber amplifiers and principal modes in multimode fiber amplifiers.

  13. Helical Fiber Amplifier

    Science.gov (United States)

    Koplow, Jeffrey P.; Kliner, Dahy; Goldberg, Lew

    2002-12-17

    A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).

  14. Spontaneous and stimulated emission in Sm{sup 3+}-doped YAl{sub 3}(BO{sub 3}){sub 4} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ryba-Romanowski, Witold [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Lisiecki, Radosław, E-mail: R.Lisiecki@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Beregi, Elena [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Budapest (Hungary); Martín, I.R. [Departamento de Física, Instituto de Materiales y Nanotecnología (IMN), Universidad de La Laguna, 38206 S/C de Tenerife, Laguna (Spain)

    2015-11-15

    Single crystals of YAl{sub 3}(BO{sub 3}){sub 4} doped with trivalent samarium were grown by the top-seeded high temperature solution method and their absorption and emission spectra were investigated. Optical pumping into prominent absorption band around 405 nm feeds the {sup 4}G{sub 5/2} metastable level giving rise to intense visible luminescence distributed in several spectral lines with the most intense line around 600 nm characterized by a branching ratio of 0.42 and peak emission cross section of 0.25×10{sup −20} cm{sup 2}. Optical amplification at 600 nm with a gain coefficient of 2.9 cm{sup −1} was achieved during a pump-and-probe experiment. - Highlights: • YAB:Sm crystal grown by the top-seeded high temperature solution method. • Spectroscopic qualities relevant for visible laser operation. • YAB:Sm single crystal used in a pump-and-probe experiment. • Optical amplification properties of samarium doped YAl{sub 3}(BO{sub 3}){sub 4}.

  15. Radio Frequency Solid State Amplifiers

    CERN Document Server

    Jacob, J

    2015-01-01

    Solid state amplifiers are being increasingly used instead of electronic vacuum tubes to feed accelerating cavities with radio frequency power in the 100 kW range. Power is obtained from the combination of hundreds of transistor amplifier modules. This paper summarizes a one hour lecture on solid state amplifiers for accelerator applications.

  16. Visible-range hybrid femtosecond systems based on a XeF(C-A) amplifier: state of the art and prospects

    Science.gov (United States)

    Alekseev, S. V.; Aristov, A. I.; Grudtsyn, Ya V.; Ivanov, N. G.; Koval'chuk, B. M.; Losev, B. F.; Mamaev, S. B.; Mesyats, Gennadii A.; Mikheev, L. D.; Panchenko, Yu N.; Polivin, A. V.; Stepanov, S. G.; Ratakhin, N. A.; Yalovoi, V. I.; Yastremskii, Arkadii G.

    2013-03-01

    Results of experimental and theoretical investigations of the hybrid (solid state/gas) visible-range femtosecond systems THL-100 (IHCE SB RAS) and THL-30 (P.N. Lebedev Physics Institute) based on a Ti : sapphire front end and a photochemical XeF(C-A) amplifier are reported. The front end generates 50-fs optical pulses with the second-harmonic (475 nm) energy of up to 5 mJ. The active medium of the amplifier is produced in a mixture XeF2 - N2 subjected to VUV radiation of xenon excited by an electron beam. The computer model is developed for calculating parameters of the XeF(C - A) amplifier, which is in a good agreement with experiments. In the THL-100 system with the 25-cm output aperture of the XeF(C-A) amplifier, a record visible-range femtosecond radiation peak power of 14 GW was obtained in a 50-fs pulse with the time contrast of above 108. The measured power of an amplified spontaneous emission of the XeF(C-A) amplifier in the angle of 0.2 mrad was 32 W. The result obtained testifies that the hybrid approach to the development of ultrahigh-power systems provides a high time contrast of radiation (greater than 1012 for the projected peak power of 100 TW). In the THL-30 system, prospects for shortening an amplified femtosecond pulse are studied and it is experimentally shown that by compensating a third-order dispersion in a hybrid system one can obtain pulses with duration of at least 27 fs with a recompression of amplified pulses in bulk glass. Also, a new phenomenon was observed of spectrum broadening and self-compression of negatively chirped femtosecond pulses in the visible range under a nonlinear interaction of wide-aperture beams with fused silica. This result opens prospects for development of the new methods of selfcompression for femtosecond pulses that are lacking physical limitations on pulse energy and realisation of self-compression of amplified pulses in the output window of the XeF(C-A) amplifier.

  17. High power, widely tunable, narrowband superfluorescent source at 2 μm based on a monolithic Tm-doped fiber amplifier.

    Science.gov (United States)

    Wang, Xiong; Jin, Xiaoxi; Zhou, Pu; Wang, Xiaolin; Xiao, Hu; Liu, Zejin

    2015-02-01

    We present a widely tunable narrowband superfluorescent source near 2 μm employing a monolithic Tm-doped fiber amplifier (TDFA), and the output power exceeds 250 W. A broadband superfluorescent source with a narrowband tunable band pass filter was used as the seed source. The spectra of the seed source can be tuned in a range of ~1930-2030 nm with full width at half maximum (FWHM) of ~1.7 nm. The Tm-doped fiber amplifier scales up the power of the seed source to a level of more than 250 W with a tuning range of ~35 nm (1966-2001 nm) and a FWHM of ~1.5-2.0 nm, and the slope efficiency is about 0.50. The output power is limited by the available pump power, and the tuning range is limited by the amplifier spontaneous emission at other wavelengths. Higher output power can be achieved if launching more pump power into the amplifier, and the tuning range can be further improved by optimizing the parameters of the TDFA. To the best of our knowledge, this is the first demonstration on a widely tunable narrowband superfluorescent source at 2 μm with average output power exceeding 250 W. PMID:25836195

  18. Electronic amplifiers for automatic compensators

    CERN Document Server

    Polonnikov, D Ye

    1965-01-01

    Electronic Amplifiers for Automatic Compensators presents the design and operation of electronic amplifiers for use in automatic control and measuring systems. This book is composed of eight chapters that consider the problems of constructing input and output circuits of amplifiers, suppression of interference and ensuring high sensitivity.This work begins with a survey of the operating principles of electronic amplifiers in automatic compensator systems. The succeeding chapters deal with circuit selection and the calculation and determination of the principal characteristics of amplifiers, as

  19. Simplified design of IC amplifiers

    CERN Document Server

    Lenk, John

    1996-01-01

    Simplified Design of IC Amplifiers has something for everyone involved in electronics. No matter what skill level, this book shows how to design and experiment with IC amplifiers. For experimenters, students, and serious hobbyists, this book provides sufficient information to design and build IC amplifier circuits from 'scratch'. For working engineers who design amplifier circuits or select IC amplifiers, the book provides a variety of circuit configurations to make designing easier.Provides basics for all phases of practical design.Covers the most popular forms for amplif

  20. The Dynamics of Semiconductor Optical Amplifiers – Modeling and Applications

    DEFF Research Database (Denmark)

    Mørk, Jesper; Nielsen, Mads Lønstrup; Berg, Tommy Winther

    2003-01-01

    The importance of semiconductor optical amplifiers is discussed. A semiconductor optical amplifier (SOA) is a semiconductor laser with anti-reflection coated facets that amplifies an injected light signal by means of stimulated emission. SOAs have a number of unique properties that open up...... significant opportunities in the area of fast, all-optical signal processing. Integrated SOA-based devices are considered suitable for future all-optical systems because of their compact size, low optical and electrical power consumption, polarization independence and high speed....

  1. High energy high repetition-rate thin-disk amplifier for OPCPA pumping

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Michael

    2013-08-15

    effect of amplified spontaneous emission (ASE) in the gain material as well as the operation of the pump laser in a burst-mode. Burst-mode operation requires a relatively long pre-pumping phase, which increases ASE related problems. A very important parameter for a large-scale OPCPA system is the timing between pump and OPCPA seed pulses. A drift would cause a loss in the temporal overlap within the crystal. Therefore, a method for the synchronization of pump and seed laser pulses in the OPCPA system by means of a two-crystal balanced optical cross-correlator has been developed and tested.

  2. High energy high repetition-rate thin-disk amplifier for OPCPA pumping

    International Nuclear Information System (INIS)

    effect of amplified spontaneous emission (ASE) in the gain material as well as the operation of the pump laser in a burst-mode. Burst-mode operation requires a relatively long pre-pumping phase, which increases ASE related problems. A very important parameter for a large-scale OPCPA system is the timing between pump and OPCPA seed pulses. A drift would cause a loss in the temporal overlap within the crystal. Therefore, a method for the synchronization of pump and seed laser pulses in the OPCPA system by means of a two-crystal balanced optical cross-correlator has been developed and tested.

  3. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  4. Wideband amplifier design

    CERN Document Server

    Hollister, Allen L

    2007-01-01

    In this book, the theory needed to understand wideband amplifier design using the simplest models possible will be developed. This theory will be used to develop algebraic equations that describe particular circuits used in high frequency design so that the reader develops a ""gut level"" understanding of the process and circuit. SPICE and Genesys simulations will be performed to show the accuracy of the algebraic models. By looking at differences between the algebraic equations and the simulations, new algebraic models will be developed that include parameters originally left out of the model

  5. REGENERATIVE TRANSISTOR AMPLIFIER

    Science.gov (United States)

    Kabell, L.J.

    1958-11-25

    Electrical circults for use in computers and the like are described. particularly a regenerative bistable transistor amplifler which is iurned on by a clock signal when an information signal permits and is turned off by the clock signal. The amplifier porforms the above function with reduced power requirements for the clock signal and circuit operation. The power requirements are reduced in one way by employing transformer coupling which increases the collector circuit efficiency by eliminating the loss of power in the collector load resistor.

  6. Quantum entanglement degrees amplifier

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Liang, Yu; Meng, Xiang-Dong; Li, Hong; Zhang, Si-Qi

    2015-01-01

    The quantum entangled degrees of entangled states become smaller with the transmission distance increasing, how to keep the purity of quantum entangled states is the puzzle in quantum communication. In the paper, we have designed a new type entanglement degrees amplifier by one-dimensional photonic crystal, which is similar as the relay station of classical electromagnetic communication. We find when the entangled states of two-photon and three-photon pass through photonic crystal, their entanglement degrees can be magnified, which make the entanglement states can be long range propagation and the quantum communication can be really realized.

  7. Universal Signal Conditioning Amplifier

    Science.gov (United States)

    Kinney, Frank

    1997-01-01

    The Technological Research and Development Authority (TRDA) and NASA-KSC entered into a cooperative agreement in March of 1994 to achieve the utilization and commercialization of a technology development for benefiting both the Space Program and U.S. industry on a "dual-use basis". The technology involved in this transfer is a new, unique Universal Conditioning Amplifier (USCA) used in connection with various types of transducers. The project was initiated in partnership with I-Net Corporation, Lockheed Martin Telemetry & Instrumentation (formerly Loral Test and Information Systems) and Brevard Community College. The project consists of designing, miniaturizing, manufacturing, and testing an existing prototype of USCA that was developed for NASA-KSC by the I-Net Corporation. The USCA is a rugged and field-installable self (or remotely)- programmable amplifier that works in combination with a tag random access memory (RAM) attached to various types of transducers. This summary report comprises performance evaluations, TRDA partnership tasks, a project summary, project milestones and results.

  8. Thermo-switchable multi-wavelength laser emission from a dye-doped nematic liquid-crystal device

    International Nuclear Information System (INIS)

    A sandwich-type laser device with a surface-relief grating inside was infiltrated with dye-doped nematic liquid-crystals which functioned as gain media. The surface-relief grating was fabricated by soft lithographic technique on a sol–gel derived zirconium-doped hybrid film using a polydimethyl–siloxane replica. The optical properties of the distributed feedback (DFB) resonator were modified by introducing a high refractive index layer consisting of niobium pentoxide subsequently. Thermal induced shift of amplified spontaneous emission spectrum, switching of multi-wavelength DFB laser emission and occurrence of random lasing were demonstrated.

  9. Detecção de emissão espontânea de luz em ensaios de colimetria aplicados ao monitoramento de efluentes sanitários Spontaneous light emission in coliforms test applied to wastewater monitoring

    OpenAIRE

    Samuel Ricardo dos Santos; José Euclides Stipp Paterniani; Cristiano de Mello Gallep

    2011-01-01

    No presente trabalho avaliou-se o potencial do emprego da técnica biofotônica ao monitoramento da qualidade microbiológica de efluentes sanitários, por meio da detecção de emissão ultrafraca de luz em testes envolvendo bactéria do grupo coliforme. Foram acompanhados os padrões de emissão de luz em câmara escura com o uso de efluente doméstico, antes e após tratamento, incubados em meio nutritivo à base de lactose e lauril triptose. O controle foi efetuado com o uso de cepa de Escherichia coli...

  10. 氧化锌纳米棒中自发辐射的回音壁模腔增强%Enhancement for Spontaneous Emission from ZnO Hexagonal Microrods Based on Whispering Gallery Mode Resonators

    Institute of Scientific and Technical Information of China (English)

    王马华; 朱光平; 朱汉清; 赵正敏

    2012-01-01

    The samples of zinc oxide nano-wires and hexagonal micro-rods are fabricated by using vapor phase transport method under the almost same conditions. Their morphology and the same crystal structures are examined and characterized by scanning electron microscopy and X-ray diffraction. The photoluminescence C PL) spectra of hexagonal samples, excited by 355 nm laser pulse with excitation power density (260 W/cm2), is measured and compared with those from nano-wires with the same exciting condition at room temperature. There are a more intensive broaden violet emission peaking at 393 nm, frequency spectrum broatening, the red shift of center wavelength and an almost disappearing green band emission in the PL of hexagonal rods while an emission peaking at 382 nm, flat green emission for wires samples. The difference of PL spectra between the two kinds of samples may be attributed to the enhancement of spontaneous emission in whispering gallery modes resonators (WGMRs) by theoretical analysis based on the theory of energy bands for semiconductors, emission from excitons, and Fermi golden rules. PL spectrum measuring experiments with higher excitation power density for the same samples are arranged to verify the theoretical analysis results, which fit with experimental results well.%应用气相传输法制备了氧化锌纳米线和具有六方对称截面的纳米棒,利用电子扫瞄显微镜,X-射线衍射仪等进行形貌与结构表征.室温下,用355nm激光脉冲,以260W/cm2相同光强激励条件,分别测量其光致发光(PL)谱,在棒状样品中发现393nm有发光峰,而线状样品是在382nm处.二者相比,棒状样品的紫光波段自发辐射光强增加、频谱展宽、中心波长红移和绿光波段辐射被显著抑制.基于半导体材料的能带理论、激子复合发光理论和费米黄金定则等,对样品PL谱差异原因进行理论分析,结果表明上述现象源于棒状样品中回音壁模谐振腔(WGMRs)的自发辐射增

  11. Spontaneous intracranial hypotension.

    LENUS (Irish Health Repository)

    Fullam, L

    2012-01-31

    INTRODUCTION: Spontaneous\\/primary intracranial hypotension is characterised by orthostatic headache and is associated with characteristic magnetic resonance imaging findings. CASE REPORT: We present a case report of a patient with typical symptoms and classical radiological images. DISCUSSION: Spontaneous intracranial hypotension is an under-recognised cause of headache and can be diagnosed by history of typical orthostatic headache and findings on MRI brain.

  12. Characterisation Of Low Noise Amplifier

    OpenAIRE

    MAULIK B.PATEL; ABHISEK CHOBEY; SUNIL B.PATEL

    2012-01-01

    Amplification is one of the most basic and prevalent microwave circuit functions inmodern RF and microwave systems. Early microwave amplifiers relied on tubes, such asklystrons and traveling-wave tubes, or solid-state reflection amplifiers based on thenegative resistance characteristics of tunnel or varactor diodes. But due to the dramaticimprovements and innovations in solid-state technology that have occurred since the1970s, most RF and microwave amplifiers today use transistor devices such...

  13. 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....

  14. Amplified leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Mahony, James

    2011-12-15

    Leaks are one of the major concerns for oil and gas producers. But recently, a Calgary-based company developed a tool that can find natural gas leaks in wellbores. This has relieved the oil and gas producers because the optics of finding downhole leaks just got a little brighter. Since then, there have been continuous efforts to broaden and refine fiber optics based methods. This paper presents amplified leak detection using fiber optics to identify even the smallest liquid leaks downhole. At high volumes, detection of downhole leaks in liquids is not a problem but at lower flow rates, the leaks become harder to detect, and at very low flow rates, they might not be detected at all. Hifi Engineering Inc. has developed the LeakSonar fiber optic acoustic sensor array that is specifically designed to detect and locate fluid migration in wellbores, even through multiple strings of casing.

  15. Metatronic transistor amplifier

    Science.gov (United States)

    Chettiar, Uday K.; Engheta, Nader

    2015-10-01

    Utilizing the notion of metamaterials, in recent years the concept of a circuit and lumped circuit elements have been extended to the optical domains, providing the paradigm of optical metatronics, i.e., metamaterial-inspired optical nanocircuitry, as a powerful tool for design and study of more complex systems at the nanoscale. In this paper we present a design for a new metatronic element, namely, a metatronic transistor that functions as an amplifier. As shown by our analytical and numerical paper here, this metatronic transistor provides gain as well as isolation between the input and output ports of such two-port device. The cascadability and fan-out aspects of this element are also explored.

  16. Binary and ternary spontaneous fission of 252 Cf

    International Nuclear Information System (INIS)

    The high selectivity and sensitivity offered by large detector arrays such as GAMMASPHERE and EUROGAM enable one to identify several gamma-rays related to the binary and ternary spontaneous fission. The yields for Mo-Ba binary spontaneous fission were extracted again from the data with better statistics. A new experiment with the 252 Cf source has been done by using a Delta telescope and GAMMASPHERE arrays at Argonne National Laboratory. From these data and our older data, new relative alpha ternary spontaneous fission yields were extracted. These results and the emission of 10 Be in spontaneous fission and the existence of long lived nuclear molecule also will be discussed. (author)

  17. Fast terahertz imaging using a quantum cascade amplifier

    International Nuclear Information System (INIS)

    A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppress lasing action, creating a THz QC amplifier. The addition of reflection from an external target to the amplifier creates enough optical feedback to initiate lasing action and the resulting emission enhances photon-assisted transport, which in turn reduces the voltage across the device. At the peak gain point, the maximum photon density coupled back leads to a prominent self-mixing effect in the QC amplifier, leading to a high sensitivity, with a signal to noise ratio up to 55 dB, along with a fast data acquisition speed of 20 000 points per second

  18. Semiconductor DC amplifier AEP 1487

    International Nuclear Information System (INIS)

    A semiconductor dc amplifier has been designed with the object of achieving low drift without component selection or special temperature-balancing adjustments. Modulator and ac-amplifier techniques have been adopted in order to avoid the drifts that occur when transistors are directly coupled. The diode-ring modulator described in CREL-902 has been used as the input chopper. (author)

  19. Spontaneous Resolution of Massive Spontaneous Tubercular Pneumothorax

    OpenAIRE

    Surya Kant; Saheer, S.; Hassan, G; Jabeed Parengal

    2012-01-01

    A 29-year-old female presented with complaints of fever and productive cough of three weeks duration. Pulmonary tuberculosis was diagnosed bacteriologically and she was prescribed antituberculosis drugs. During follow-up she developed massive pneumothorax, for which patient refused surgical management and was managed conservatively. After six months there was complete spontaneous resolution of pneumothorax. The unusual presentation and unexpected outcome prompted us to report this case.

  20. GeSn waveguide structures for efficient light detection and emission

    Science.gov (United States)

    Lin, You-Long; Huang, Yu-Hui; Chen, Shao-Wei; Chang, Guo-En

    2015-02-01

    We report the fabrication and characterization of GeSn waveguide structures on Si substrates grown by molecular beam epitaxy for efficient light-detection and emission. For photodetectors, GeSn waveguide structures exhibit a higher optical response compared to a reference Ge device as revealed by the photocurrent experiments. For light-emission, room-temperature photoluminescence experiments show a redshifted emission wavelength for the GeSn samples compared to the Ge reference sample due to the Sn incorporation. Besides, we observe ripple characteristics in the amplified spontaneous emission spectrum of the GeSn waveguide structure, which are attributed to the waveguide modes. Those results suggest that GeSn waveguide structures are promising for high-performance Si-based lightdetectors and emitters integrable with Si electronics.

  1. On the relativistic calculation of spontaneous emission

    International Nuclear Information System (INIS)

    In a recent work, Barut and Salamin (1988) have derived a method for calculating the relativistic decay rates in atoms, in a formulation of quantum electrodynamics based upon the electron's self-energy. The decay rate appears as the imaginary part of a formula giving a complex energy shift, the real part of the formula being the Lamb shift. The presence of the the decay rate in the imaginary part of a formula, giving an energy in its real part, may appear a bit strange. A confirmation of the Barut and Alamin calculation, by means of a quite different point of view, would be useful. Therefore in this work the Einstein A coefficients are calculated, in all cases of degeneracies of the Dirac transition currents, by means of the energy balance method. This point of view is based on the balance between the energy released during the transitions of electrons from a higher state to a lower one, and the flux of the Poynting vector of the classical electromagnetic field, created by the electrons, through a sphere a large radius. The particularity of the present work lies in the direct calculation of the relativistic Dirac transition currents and the fact that the dipole and Pauli approximations are avoided. The quantum part of the relativistic calculation is based on the determination of the transition charge currents in the Darwin solutions of the Dirac equation. 13 refs

  2. Spontaneous pneumomediastinum in adolescents

    Institute of Scientific and Technical Information of China (English)

    SHEN Gang; CHAI Ying

    2007-01-01

    @@ Spontaneous pneumomediastinum (SPM),reported firstly by Hamman in 1939,is an uncommon,and usually benign,and self-limiting clinical disorder found in young people often without apparent precipitating factors or diseases.

  3. Spontaneous Rupture of Pyometra

    OpenAIRE

    Fatemeh Mallah; Tahere Eftekhar; Mohammad Naghavi-Behzad

    2013-01-01

    Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract and other causes of acute abdomen. In most cases, a correct and definite diagnosis can be made only by laparotomy. We report two cases of diffuse peritonitis caused by spontaneous perforated pyometra. The first case is a 78-year-old woman with abdominal pain for which laparotomy was performed because of suspected incarcerated he...

  4. Nonlinear carrier dynamics in a quantum dash optical amplifier

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Ek, Sara; Yvind, Kresten;

    2012-01-01

    Results of experimental pump-probe spectroscopy of a quantum dash optical amplifier biased at transparency are presented. Using strong pump pulses we observe a competition between free carrier absorption and two-photon induced stimulated emission that can have drastic effects on the transmission...

  5. Small signal microwave amplifier design

    CERN Document Server

    Grosch, Theodore

    2000-01-01

    This book explains techniques and examples for designing stable amplifiers for high-frequency applications in which the signal is small and the amplifier circuit is linear. An in-depth discussion of linear network theory provides the foundation needed to develop actual designs. Examples throughout the book will show you how to apply the knowledge gained in each chapter leading to the complex design of low noise amplifiers. Many exercises at the end of each chapter will help students to practice their skills. The solutions to these design problems are available in an accompanying solutions book

  6. International Standardization Activities for Optical Amplifiers

    Institute of Scientific and Technical Information of China (English)

    Haruo Okamura

    2003-01-01

    International standardization activities for Optical Amplifiers at IECTC86 and ITU-T SG15 are reviewed. Current discussions include Optical Amplifier safety guideline, Reliability standard, Rest methods of Noise and PMD, Definitions of Raman amplifier parameters and OA classification.

  7. Spontaneous pneumomediastinum in adult dermatomyositis.

    OpenAIRE

    Bradley, J D

    1986-01-01

    Spontaneous pneumomediastinum has not been reported in adult polymyositis or dermatomyositis, either in conjunction with spontaneous pneumothorax or in isolation. Spontaneous pneumothorax has been rarely reported as a complication of rheumatoid arthritis, systemic lupus erythematosus, scleroderma, and childhood dermatomyositis. It is associated with active, progressive pulmonary involvement and a poor prognosis. We describe an adult with dermatomyositis and spontaneous pneumomediastinum with ...

  8. Analysis of optical amplifier noise in coherent optical communication systems with optical image rejection receivers

    DEFF Research Database (Denmark)

    Jørgensen, Bo Foged; Mikkelsen, Benny; Mahon, Cathal J.

    1992-01-01

    -spontaneous beat noise (SP-SP) can all be reduced by 3 dB, thereby doubling the dynamic range of the optical amplifier. A 2.5-dB improvement in dynamic range has been demonstrated experimentally with the all-optical image rejection configuration. The implications of the increased dynamic range thus obtained are...

  9. Raman and loss induced quantum noise in depleted fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, C. J.

    2013-01-01

    We present a semi-classical approach for predicting the quantum noise properties of fiber optical parametric amplifiers. The unavoidable contributors of noise, vacuum fluctuations, loss-induced noise, and spontaneous Raman scattering, are included in the analysis of both phase-insensitive and phase...

  10. A Transformer Class E Amplifier

    Directory of Open Access Journals (Sweden)

    Mikolajewski Miroslaw

    2014-12-01

    Full Text Available In a high-efficiency Class E ZVS resonant amplifier a matching and isolation transformer can replace some or even all inductive components of the amplifier thus simplifying the circuit and reducing its cost. In the paper a theoretical analysis, a design example and its experimental verification for a transformer Class E amplifier are presented. In the experimental amplifier with a transformer as the only inductive component in the circuit high efficiency ηMAX = 0.95 was achieved for supply voltage VI = 36 V, maximum output power POMAX = 100 W and the switching frequency f = 300 kHz. Measured parameters and waveforms showed a good agreement with theoretical predictions. Moreover, the relative bandwidth of the switching frequency was only 19% to obtain output power control from 4.8 W to POMAX with efficiency not less than 0.9 in the regulation range.

  11. TARC: Carlo Rubbia's Energy Amplifier

    CERN Multimedia

    Laurent Guiraud

    1997-01-01

    Transmutation by Adiabatic Resonance Crossing (TARC) is Carlo Rubbia's energy amplifier. This CERN experiment demonstrated that long-lived fission fragments, such as 99-TC, can be efficiently destroyed.

  12. New Packaging for Amplifier Slabs

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  13. Transistor oscillator and amplifier grids

    OpenAIRE

    Weikle, Robert M., II; Kim, Moonil; Hacker, Jonathan B.; De Lisio, Michael P.; Popvić, Zoya B.; Rutledge, David B.

    1992-01-01

    Although quasi-optical techniques are applicable to a large variety of solid-state devices, special attention is given to transistors, which are attractive because they can be used as either amplifiers or oscillators. Experimental results for MESFET bar-grid and planar grid oscillators are presented. A MESFET grid amplifier that receives only vertically polarized waves at the input and radiates horizontally polarized waves at the output is discussed. These planar grids can be scaled for opera...

  14. A KIND OF NEW AMPLIFIER

    Institute of Scientific and Technical Information of China (English)

    YIN XUN-HE; FENG RU-PENG; REN YONG

    2000-01-01

    Chaotic characteristics in the iteration of logistic map (one-dimensional discrete dynamic system) are simulatedand analyzed. The circuit implementation of a kind of chaotic amplifier model is based on the chaotic characteristicsthat chaos is sensitively dependent on its initial conditions, and the circuit simulation result is given using simulationprogram with integrated circuit emphasis for personal computer (PSPICE), and is compared with linear amplifier.Advantages and disadvantages of such a model are indicated.

  15. Casimir force on amplifying bodies

    OpenAIRE

    Sambale, Agnes; Welsch, Dirk-Gunnar; Buhmann, Stefan Yoshi; Dung, Ho Trung

    2009-01-01

    Based on a unified approach to macroscopic QED that allows for the inclusion of amplification in a limited space and frequency range, we study the Casimir force as a Lorentz force on an arbitrary partially amplifying system of linearly locally responding (isotropic) magnetoelectric bodies. We demonstrate that the force on a weakly polarisable/magnetisable amplifying object in the presence of a purely absorbing environment can be expressed as a sum over the Casimir--Polder forces on the excite...

  16. Case of spontaneous ventriculocisternostomy

    Energy Technology Data Exchange (ETDEWEB)

    Yamane, Kanji; Yoshimoto, Hisanori; Harada, Kiyoshi; Uozumi, Tohru (Hiroshima Univ. (Japan). School of Medicine); Kuwabara, Satoshi

    1983-05-01

    The authors experienced a case of spontaneous ventriculocisternostomy diagnosed by CT scan with metrizamide and Conray. Patient was 23-year-old male who had been in good health until one month before admission, when he began to have headache and tinnitus. He noticed bilateral visual acuity was decreased about one week before admission and vomiting appeared two days before admission. He was admitted to our hospital because of bilateral papilledema and remarkable hydrocephalus diagnosed by CT scan. On admission, no abnormal neurological signs except for bilateral papilledema were noted. Immediately, right ventricular drainage was performed. Pressure of the ventricle was over 300mmH/sub 2/O and CSF was clear. PVG and PEG disclosed an another cavity behind the third ventricle, which was communicated with the third ventricle, and occlusion of aqueduct of Sylvius. Metrizamide CT scan and Conray CT scan showed a communication between this cavity and quadrigeminal and supracerebellar cisterns. On these neuroradiological findings, the diagnosis of obstructive hydrocephalus due to benign aqueduct stenosis accompanied with spontaneous ventriculocisternostomy was obtained. Spontaneous ventriculocisternostomy was noticed to produce arrest of hydrocephalus, but with our case, spontaneous regression of such symptoms did not appeared. By surgical ventriculocisternostomy (method by Torkildsen, Dandy, or Scarff), arrest of hydrocephalus was seen in about 50 to 70 per cent, which was the same results as those of spontaneous ventriculocisternostomy. It is concluded that VP shunt or VA shunt is thought to be better treatment of obstructive hydrocephalus than the various kinds of surgical ventriculocisternostomy.

  17. Spontaneous genetic clustering in populations of competing organisms

    International Nuclear Information System (INIS)

    We introduce and analyse an individual-based evolutionary model, in which a population of genetically diverse organisms compete with each other for limited resources. Through theoretical analysis and stochastic simulations, we show that the model exhibits a pattern-forming instability which is highly amplified by the effects of demographic noise, leading to the spontaneous formation of genotypic clusters. This mechanism supports the thesis that stochasticity has a central role in the formation and coherence of species. (paper)

  18. Statistics of multiphoton events in spontaneous parametric down-conversion

    OpenAIRE

    Wasilewski, Wojciech; Radzewicz, Czeslaw; Frankowski, Robert; Banaszek, Konrad

    2008-01-01

    We present an experimental characterization of the statistics of multiple photon pairs produced by spontaneous parametric down-conversion realized in a nonlinear medium pumped by high-energy ultrashort pulses from a regenerative amplifier. The photon number resolved measurement has been implemented with the help of a fiber loop detector. We introduce an effective theoretical description of the observed statistics based on parameters that can be assigned direct physical nterpretation. These pa...

  19. Spontaneous Perforation of Pyometra

    Directory of Open Access Journals (Sweden)

    Begüm Yildizhan

    2006-01-01

    Full Text Available Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01–0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy. Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture.

  20. Residential Exposure to Traffic and Spontaneous Abortion

    OpenAIRE

    Green, Rochelle S; Malig, Brian; Windham, Gayle C.; Fenster, Laura; Ostro, Bart; Swan, Shanna

    2009-01-01

    Background Studies have shown associations between air pollution or traffic exposure and adverse birth outcomes, such as low birth weight. However, very few studies have examined the effect of traffic emissions on spontaneous abortion (SAB). Objective The goal of this study was to determine whether residential exposure to vehicular traffic was associated with SAB. Methods Pregnant women from a prepaid health plan in California were recruited into a prospective cohort study in 1990–1991. Three...

  1. Spontaneous regression of osteochondromas

    Energy Technology Data Exchange (ETDEWEB)

    Hoshi, Manabu; Takami, Masatsugu; Hashimoto, Ryouji; Okamoto, Takashi; Yanagida, Ikuhisa; Matsumura, Akira; Noguchi, Kazuko [Yodogawa Christian Hospital, Department of Orthopaedic Surgery, Osaka (Japan)

    2007-06-15

    Spontaneous regression of an osteochondroma is an infrequent event. In this report, two cases with spontaneous regression of osteochondromas are presented. The first case was a solitary osteochondroma of the pedunculated type involving the right proximal humerus in a 7-year-old boy. This lesion resolved over 15 months of observation. The second case was a 3-year-old girl with multiple osteochondromatosis, in whom sessile osteochondromas of the right tibia and left fibula regressed over 33 months.The mechanism of this phenomenon is discussed with a review of previous reports. Regarding treatment, careful observation may be acceptable for typical osteochondromas, especially in young children. (orig.)

  2. [Spontaneous mediastinal emphysema].

    Science.gov (United States)

    Svedbrand, Charlotte; Lange, Peter; Nielsen, Klaus

    2016-01-01

    Spontaneous mediastinal emphysema, also known as spontaneous pneumomediastinum, is defined as radiologically detected free air in the mediastinum, without preceding trauma. It is a rare condition, mainly affecting young adults. It can be caused by coughing, strenuous sports or cocaine inhalation, however, 40% are idiopatic. Common symptoms are chest pain and dyspnoea. 75-90% can be diagnosed with a chest X-ray, and 100% with a computed tomography. Treatment is symptomatic and complications are rare, however, pneumothorax and pneumorrachis have been reported. PMID:26750190

  3. Spontaneous tension haemopneumothorax

    Directory of Open Access Journals (Sweden)

    Itam Sarah

    2008-10-01

    Full Text Available Abstract We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such case reported. Aetiology and current approach to spontaneous haemothorax are discussed briefly.

  4. Tapered amplifier laser with frequency-shifted feedback

    CERN Document Server

    Bayerle, A; Vlaar, P; Pasquiou, B; Schreck, F

    2016-01-01

    We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

  5. Low-Noise Band-Pass Amplifier

    Science.gov (United States)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  6. Spontaneous otogenic pneumocephalus.

    Science.gov (United States)

    Mohammed, El Romyssa; Profant, Milan

    2011-06-01

    The diagnosis and management of spontaneous otogenic pneumocephalus with literature review is described. A young sportsman experienced headache and fluctuating mass in his occiput during increased physical activity. A large extradural intracranial pneumocephalus with corresponding emphysema was imaged on a CT scan. Transmastoid identification and plugging of temporal bone defect solved the problem with complete pneumocephalus and emphysema resorption. PMID:21254960

  7. EMI-resilient amplifier circuits

    CERN Document Server

    van der Horst, Marcel J; Linnenbank, André C

    2014-01-01

    This book enables circuit designers to reduce the errors introduced by the fundamental limitations and electromagnetic interference (EMI) in negative-feedback amplifiers.  The authors describe a systematic design approach for application specific negative-feedback amplifiers, with specified signal-to-error ratio (SER).  This approach enables designers to calculate noise, bandwidth, EMI, and the required bias parameters of the transistors used in  application specific amplifiers in order to meet the SER requirements.   ·         Describes design methods that incorporate electromagnetic interference (EMI) in the design of application specific negative-feedback amplifiers; ·         Provides designers with a structured methodology to avoid the use of trial and error in meeting signal-to-error ratio (SER) requirements; ·         Equips designers to increase EMI immunity of the amplifier itself, thus avoiding filtering at the input, reducing the number of components and avoiding detr...

  8. Spectroscopic amplifier for pin diode

    International Nuclear Information System (INIS)

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  9. Use of the Lorentz-Boosted Frame Transformation to Simulate Free-Electron Laser Amplifier Physics

    International Nuclear Information System (INIS)

    Recently it has been pointed out that numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz boosted frame. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy (E0 (ge) 250 MeV) electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor gamma F, the red-shifted FEL radiation and blue shifted undulator have identical wavelengths and the number of required time-steps (presuming the Courant condition applies) decreases by a factor of g2 F for fully electromagnetic simulation. We have adapted the WARP code to apply this method to several FEL problems including coherent spontaneous emission (CSE) from pre-bunched e-beams, and strong exponential gain in a single pass amplifier configuration. We discuss our results and compare with those from the 'standard' FEL simulation approach which adopts the eikonal approximation for propagation of the radiation field

  10. Spontaneous pneumothorax complicating Legionnaires' disease

    OpenAIRE

    Bali, A; Pierry, A. A.; Bernstein, A.

    1981-01-01

    Spontaneous pneumothorax is a known but rare complication of pneumonia in adults. A case is described of Legionnaires' disease complicated by spontaneous hydropneumothorax. So far as is known such an association has not been reported previously.

  11. Gaussian amplifier for nuclear spectrometry

    International Nuclear Information System (INIS)

    One of the major goals of nuclear spectrometry is the determination of the energy spectrum of a radioactive source. To measure this spectrum with electronic instrumentation one need to use a nuclear spectrometry chain of which the amplifier is part of, and whose filter shaping considerably influences the final energy resolution achieved. The amplifier released accomplishes a 7th order Gaussian filter shape with Taylor series approximation synthesized by the Shifted Companion Form and mounted using only electronic components availablein Brazil. The final version has been tested and the results showed a very good performance and the energy resolution achieved was equivalent to the imported models. (Author)

  12. Spontaneous Quantum Hall Liquids

    Science.gov (United States)

    Zhang, Fan

    2012-02-01

    Driven by electron-electron interactions, bilayer graphene and its thicker cousins, chirally (ABC) stacked multilayers, exhibit a variety of distinct broken symmetry states in which each spin-valley flavor spontaneously transfers charge between layers, because of their flat touching bands and large pseudospin chiralities. These gapped states are accompanied by large momentum space Berry curvatures and different types of topological orders. These competing ground states are distinguished by their flavor Hall conductivities, orbital magnetizations, edge state properties, and response to external fields. These spontaneous quantum Hall (SQH) states at zero field smoothly evolve into quantum Hall ferromagnet states at finite field. Various phase transitions occur by tuning carrier densities, temperature, and external fields. Recently, SQH states have started to be observed and explored in transport and Hall experiments on suspended devices with dual gates.

  13. Spontaneous Perforation of Pyometra.

    Science.gov (United States)

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-04-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perforation was performed. Although spontaneously perforated pyometra is rare, the condition must be borne in mind with regard to elderly women with acute abdominal pain. Preoperative diagnosis of perforated pyometra is absolutely essential. Computed tomography (CT) and MRI are diagnostic tools. In selected cases conservative approach at surgery can be opted. PMID:27152313

  14. Spontaneous Rupture of Pyometra

    Directory of Open Access Journals (Sweden)

    Fatemeh Mallah

    2013-01-01

    Full Text Available Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract and other causes of acute abdomen. In most cases, a correct and definite diagnosis can be made only by laparotomy. We report two cases of diffuse peritonitis caused by spontaneous perforated pyometra. The first case is a 78-year-old woman with abdominal pain for which laparotomy was performed because of suspected incarcerated hernia. The second case is a 61-year-old woman with abdominal pain for which laparotomy was performed because of symptoms of peritonitis. At laparotomy of both cases, 1 liter of pus with the source of uterine was found in the abdominal cavity. The ruptured uterine is also detected. More investigations revealed no malignancy as the reason of the pyometra.

  15. Spontaneous ovarian hyperstimulation syndrome.

    OpenAIRE

    Kasum, Miro; Orešković, Slavko; Ježek, Davor

    2013-01-01

    Spontaneous forms of the ovarian hyperstimulation syndrome (sOHSS) are nearly always reported between 8 and 14 weeks of pregnancy and also with follicle-stimulating hormone (FSH) producing pituitary adenoma. The syndrome has been previously reported in rare instances of increased production of human chorionic gonadotrophin (hCG) such as multiple pregnancies, hydatiforme mole, polycystic ovary disease and elevated concentrations of thyroid-stimulating hormone (TSH) in hypothyreoidism. High lev...

  16. Spontaneous Perforation of Pyometra

    OpenAIRE

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-01-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perfor...

  17. Spontaneous spinal epidural abscess.

    LENUS (Irish Health Repository)

    Ellanti, P

    2011-10-01

    Spinal epidural abscess is an uncommon entity, the frequency of which is increasing. They occur spontaneously or as a complication of intervention. The classical triad of fever, back pain and neurological symptoms are not always present. High index of suspicion is key to diagnosis. Any delay in diagnosis and treatment can have significant neurological consequences. We present the case of a previously well man with a one month history of back pain resulting from an epidural abscess.

  18. RF radiation measurement on the indigenously developed solid state amplifier

    International Nuclear Information System (INIS)

    A Solid State Radio Frequency (RF) Power Amplifier module for 300 W has been developed indigenously around 350 MHz centre frequency. A shielding enclosure for the amplifier has been designed to confine the non- ionizing - radiated and conducted emissions inside the enclosure. This design has been simulated in CST microwave studio and E fields and H fields were monitored around the enclosed amplifier. These simulated results for radiated and conducted fields have been presented here. Then the enclosure has been assembled with the amplifier. For this enclosed assembly, RF radiated and conducted field emissions were monitored outside the enclosure. In this paper, measurement methodology for the radiated and conducted field has been described. These measurements have been done according to established standards for the operating frequency range. Measurements have been carried out using an omenidirectional, frequency selective electromagnetic field measuring instrument. Measured field levels for this assembly have been compared with the ICNIRP defined safety limits for personal and occupational safety hazards. This paper describes in detail, all the measurements and their analysis. (author)

  19. A wideband dc-coupled amplifier

    International Nuclear Information System (INIS)

    A method is described whereby an ac-coupled high-frequency amplifier and a dc-coupled low-frequency amplifier are connected in parallel in order to obtain a dc-coupled wideband amplifier. By using an operational amplifier which compares the output voltage with the input voltage, the low-frequency amplifier contributes to the overall gain only when the gain of the ac-coupled amplifier droops at low frequencies. Thus, no frequency splitting networks are necessary and the excellent low-frequency features of an operational amplifier are added to those of the ac-coupled wideband amplifier. As an example, a low noise amplifier is described which exhibits a hundredfold gain, a bandwidth from dc to 550 MHz, an input bias current of less than 1 nA, and an output voltage range of ±1 V

  20. Characterisation Of Low Noise Amplifier

    Directory of Open Access Journals (Sweden)

    MAULIK B.PATEL

    2012-08-01

    Full Text Available Amplification is one of the most basic and prevalent microwave circuit functions inmodern RF and microwave systems. Early microwave amplifiers relied on tubes, such asklystrons and traveling-wave tubes, or solid-state reflection amplifiers based on thenegative resistance characteristics of tunnel or varactor diodes. But due to the dramaticimprovements and innovations in solid-state technology that have occurred since the1970s, most RF and microwave amplifiers today use transistor devices such as Si or SiGeBJTs, GaAs HBTs, GaAs or InP FETs, or GaAs HEMTs. Microwave transistor amplifiersare rugged, low-cost, reliable, and can be easily integrated in both hybrid andmonolithic integrated circuitry. Transistor amplifiers can be used at frequencies inexcess of 100 GHz in a wide range of applications requiring small size, low-noise figure,broad bandwidth, and low to medium power capacity. Although microwave tubes are stillrequired for very high power and/or very high frequency applications, continuingimprovement in the performance of microwave transistors is steadily reducing the needfor microwave tubes

  1. Dielectric waveguide amplifiers and lasers

    NARCIS (Netherlands)

    Pollnau, M.

    2014-01-01

    The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length o

  2. [Spontaneous abortion. Etiologic survey. Results].

    Science.gov (United States)

    Baaklini, N; Anguenot, J L; Boulanger, J C; Vitse, M

    1990-12-01

    The definition of repeated spontaneous abortions is subject to caution. For some, it corresponds to at least three repeated spontaneous abortions with no normal previous pregnancy; for others, it comprises the repeated spontaneous abortions occurring after a normal pregnancy. It is a frequent problem, especially if one tries to give a wider definition. The authors studied the frequency of repeated spontaneous abortions in a continuous series of 14,857 pregnancies which took place between January 1982 and December 1988. In the study of the aetiology of the repeated spontaneous abortions in the various groups of women defined according to the number of previous pregnancies and abortions, they find the classical causes of repeated spontaneous abortions in all the categories: therefore, it seems legitimate to them that a wider definition be given for repeated spontaneous abortions. PMID:2291048

  3. Polymer/Perovskite Amplifying Waveguides for Active Hybrid Silicon Photonics.

    Science.gov (United States)

    Suárez, Isaac; Juárez-Pérez, Emilio J; Bisquert, Juan; Mora-Seró, Iván; Martínez-Pastor, Juan P

    2015-10-28

    The emission properties of hybrid halide perovskites are exploited to implement a stable and very low power operation waveguide optical amplifier integrated in a silicon platform. By optimizing its design with a poly(methyl methacrylate) (PMMA) encapsulation, this novel photonic device presents a net gain of around 10 dB cm(-1) and 3-4 nm linewidth with an energy threshold as low as 2 nJ pulse(-1) and exhibiting no degradation after one year. PMID:26331838

  4. Low Cost RF Amplifier for Community TV

    Science.gov (United States)

    Ch, Syafaruddin; Sasongko, Sudi Mariyanto Al; Made Budi Suksmadana, I.; Mustiko Okta Muvianto, Cahyo; Ariessaputra, Suthami

    2016-01-01

    he capability of television to deliver audio video makes this media become the most effective method to spread information. This paper presents an experiment of RF amplifier design having low-cost design and providing sufficient RF power particularly for community television. The RF amplifier consists of two stages of amplifier. The first stage amplifier was used to leverage output of TV modulator from 11dBm to enable to drive next stage amplifier. CAD simulation and fabrication were run to reach optimum RF amplifier design circuit. The associated circuit was made by determining stability circle, stability gain, and matching impedance. Hence, the average power of first stage RF amplifier was 24.68dBm achieved. The second stage used RF modules which was ready match to 50 ohm for both input and output port. The experiment results show that the RF amplifier may operate at frequency ranging from 174 to 230MHz. The average output power of the 2nd stage amplifier was 33.38 Watt with the overall gain of 20.54dB. The proposed RF amplifier is a cheap way to have a stable RF amplifier for community TV. The total budget for the designed RF amplifier is only a 1/5 compared to local design of final TV amplifier.

  5. Angular dependent light emission from planar waveguides

    International Nuclear Information System (INIS)

    We have investigated the angular dependence of amplified spontaneous emission (ASE) and laser emission from an asymmetric and free-standing polymer thin films doped with rhodamine 6G, which is transversely pumped by a pulsed Nd:YAG laser. A semi-leaky waveguide or quasi-waveguide structure has been developed by spin coating technique. In these waveguides, the light was confined by the film/air-film/glass substrate interfaces. At the film/substrate interface, a portion of light will reflect back into the film (guided mode) and the remaining refracted to the substrate resulting in cutoff modes. A blue-shift in ASE has been observed when the pump power was increased from 8 to 20 mW allowing a limited range of tuning of emission wavelength. To study the directionality of the ASE from the waveguide, we have measured the output intensity and FWHM of emission spectra as a function of viewing angle (θ) from the plane parallel to film. From the detailed examination of the output emission spectra, as +θ increases from 0° there has been an initial decrease in output intensity, but at a particular angle ≈10° an increase in output intensity was observed. This additional peak in output intensity as +θ is a clear indication of coexistence of the cutoff mode. We also present a compact solid-state laser based on leaky mode propagation from the dye-doped polymer free-standing film (∼50 μm thickness) waveguide. The partial reflections from the broad lateral surfaces of the free-standing films provided the optical feedback for the laser emission with high directionality. For a pump power of 22 mW, an intense line with FWHM <0.2 nm was observed at 578 nm

  6. Amplifying the evanescent field of free electrons

    OpenAIRE

    So, J.-K.; Ou, J.-Y.; Adamo, G.; García de Abajo, F. J.; MacDonald, K. F.; Zheludev, N.I.

    2013-01-01

    We provide the first experimental demonstration that the evanescent field of free electrons can be amplified by a plasmonic nanolayer in much that same way as optical evanescent fields are amplified in the ‘poor-man’s superlens’.

  7. Amplifying free-electron evanescent fields

    OpenAIRE

    So, J.-K.; Ou, J.-Y.; Adamo, G.; García de Abajo, F. J.; MacDonald, K. F.; Zheludev, N.I.

    2013-01-01

    We show experimentally for the first time that free-electron evanescent fields can be amplified by a plasmonic nanolayer in a manner analogous to the way in which optical fields are amplified in the poor-man's superlens.

  8. Analog circuit design designing high performance amplifiers

    CERN Document Server

    Feucht, Dennis

    2010-01-01

    The third volume Designing High Performance Amplifiers applies the concepts from the first two volumes. It is an advanced treatment of amplifier design/analysis emphasizing both wideband and precision amplification.

  9. Compact dual channel spectroscopy amplifier cum discriminator

    International Nuclear Information System (INIS)

    A single width NIM module having two channels of spectroscopy amplifier cum discriminator has been developed for Nuclear Physics experiments at IUAC. Each channel contains a shaping amplifier along with logic circuits to generate the energy and timing information respectively

  10. Spontaneous Collapse of Supersymmetry

    CERN Document Server

    Buchholz, D A; Buchholz, Detlev; Ojima, Izumi

    1997-01-01

    It is shown that, if generators of supersymmetry transformations (supercharges) can be defined in a spatially homogeneous physical state, then this state describes the vacuum. Thus, supersymmetry is broken in any thermal state and it is impossible to proceed from it by ``symmetrization'' to states on which an action of supercharges can be defined. So, unlike the familiar spontaneous breakdown of bosonic symmetries, there is a complete collapse of supersymmetry in thermal states. It is also shown that spatially homogeneous superthermal ensembles are never supersymmetric.

  11. Kahal as Spontaneous Order

    OpenAIRE

    Joseph Isaac Lifshitz

    2009-01-01

    One description of the people of Israel is Kahal, a category that the Talmud is also concerned with. This category was further employed later in the middle ages, and was given to the Jewish community, although some times with a little twist, the Kehila. This paper will focus mainly on the question of the formation of the Kahal as a large political body in the Bible and in the Talmud, and explore the political implications that can be derived from it. The Kahal as a spontaneously-defined, non-...

  12. Spontaneously broken mass

    CERN Document Server

    Endlich, Solomon; Penco, Riccardo

    2013-01-01

    The Galilei group involves mass as a central charge. We show that the associated superselection rule is incompatible with the observed phenomenology of superfluid helium 4: this is recovered only under the assumption that mass is spontaneously broken. This remark is somewhat immaterial for the real world, where the correct space-time symmetries are encoded by the Poincar\\'e group, which has no central charge. Yet it provides an explicit example of how superselection rules can be experimentally tested. We elaborate on what conditions must be met for our ideas to be generalizable to the relativistic case of the integer/half-integer angular momentum superselection rule.

  13. Single conversion stage amplifier - SICAM

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2005-12-15

    This Ph.D. thesis presents a thorough analysis of the so called SICAM - SIngle Converter stage AMplifier approach to building direct energy conversion audio power amplifiers. The mainstream approach for building isolated audio power amplifiers today consists of isolated DC power supply and Class D amplifier, which essentially represents a two stage solution, where each of the components can be viewed as separate and independent part. The proposed SICAM solution strives for direct energy conversion from the mains to the audio output, by dedicating the operation of the components one to another and integrating their functions, so that the final audio power amplifier represents a single-stage topology with higher efficiency, lower volume, less board space, lower component count and subsequently lower cost. The SICAM approach is both applicable to non-isolated and isolated audio power amplifiers, but the problems encountered in these two cases are different. Non-isolated SICAM solutions are intended for both AC mains-connected and battery-powered devices. In non-isolated mains-connected SICAMs the main idea is to simplify the power supply or even provide integrated power factor correction (PFC) functions, while still maintaining low component stress and good audio performance by generally decreasing the input voltage level to the Class D audio power amplifier. On the other hand, non-isolated battery-powered SICAMs have to cope with the ever changing battery voltage and provide output voltage levels which are both lower and higher than the battery voltage, while still being simple and single-stage energy conversion solutions. In isolated SICAMs the isolation transformer adjusts the voltage level on the secondary side to the desired level, so the main challenges here are decreasing the size of the magnetic core and reducing the number and size of bulky reactive components as much as possible. The main focus of this thesis is directed towards the isolated SICAMs and

  14. European Research on THz Vacuum Amplifiers

    DEFF Research Database (Denmark)

    Brunetti, F.; Cojocarua, C.-S.; de Rossi, A.; Di Carlo, A.; Dispenza, M.; Dolfi, D.; Durand, A.; Fiorello, A.; Gohier, A.; Guiset, P.; Korantia, M.; Krozer, V.; Legagneux, P.; Marchesin, R.; Megtert, S.; Bouamrane, F.; Mineo, M.; Paoloni, C.; Pham, K.; Schnell, J.P.; Secchi, A.; Tamburri, E.; Terranova, M.L.; Ulisse, G.; Zhurbenko, Vitaliy

    The OPTHER (OPtically Driven TeraHertz AmplifiERs) project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within this project is a consolidation of efforts at the international level from the main players of the Eu...... European research, academy and industry in vacuum electronics. This paper describes the status of the project and progress towards the THz amplifier realization....

  15. Improved charge amplifier using hybrid hysteresis compensation

    Science.gov (United States)

    Amin-Shahidi, Darya; Trumper, David L.

    2013-08-01

    We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.

  16. Quantum Theory of Laser Amplifiers.

    Science.gov (United States)

    Mander, Gillian Linda

    Available from UMI in association with The British Library. Requires signed TDF. We calculate the input-output characteristics of a below threshold laser amplifier. Expressions are derived for the output second- and fourth-order spectral and temporal correlation functions in terms of the corresponding input quantities, and for the photocount first and second factorial moments for both homodyne and direct detection. The general results are applied to several cases of practical interest, including specific non-classical input states. We show that a maximum of twofold amplification is permitted if squeezing in the input is to survive at the output. Similarly, for preservation of photon antibunching in amplification we show that only very small gains are allowed. The model treated here provides a detailed example of the amplifier noise limitations imposed by quantum mechanics. In particular, we show that minimum noise occurs in a cavity that is asymmetric with respect to the mirror reflectivities. The latter part of this work treats the above threshold laser amplifier. The laser output is back-scattered from a moving target to provide a weak Doppler-shifted signal which re-enters the laser cavity and is amplified. We show that the three-level atomic lasing medium is equivalent to a two-level medium pumped by an inverted bath. We use the methods of quantum statistical analysis to obtain time -evolution equations for the c-number amplitudes of the laser and signal fields. We show that the results may be applied to the below threshold regime for appropriate values of the pump parameter. By considering the amplitude differential gain we show explicitly that the behaviour of the laser around threshold is characteristic of a second -order phase transition. We calculate the output intensity gain appropriate to a heterodyne detection process, and find good agreement between the predicted gain profiles and measured data for both carbon dioxide and argon-ion lasers.

  17. Einstein's coefficients and the nature of thermal radio emission

    OpenAIRE

    Prigara, F. V.

    2001-01-01

    The relations between Einstein's coefficients for spontaneous and induced emission of radiation with account for the natural linewidth are obtained . It is shown that thermal radio emission is stimulated one . Thermal radio emission of non-uniform gas is considered .

  18. Compact, harmonic multiplying gyrotron amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H. [Univ. of Maryland, College Park, MD (United States). Inst. for Plasma Research

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  19. SPS RF System Amplifier plant

    CERN Multimedia

    1977-01-01

    The picture shows a 2 MW, 200 MHz amplifier plant with feeder lines. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X.

  20. European Research on THz Vacuum Amplifiers

    DEFF Research Database (Denmark)

    Brunetti, F.; Cojocarua, C.-S.; de Rossi, A.;

    2010-01-01

    The OPTHER (OPtically Driven TeraHertz AmplifiERs) project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within this project is a consolidation of efforts at the international level from the main players of the Eu...

  1. NASA developments in solid state power amplifiers

    Science.gov (United States)

    Leonard, Regis F.

    1990-01-01

    Over the last ten years, NASA has undertaken an extensive program aimed at development of solid state power amplifiers for space applications. Historically, the program may be divided into three phases. The first efforts were carried out in support of the advanced communications technology satellite (ACTS) program, which is developing an experimental version of a Ka-band commercial communications system. These first amplifiers attempted to use hybrid technology. The second phase was still targeted at ACTS frequencies, but concentrated on monolithic implementations, while the current, third phase, is a monolithic effort that focusses on frequencies appropriate for other NASA programs and stresses amplifier efficiency. The topics covered include: (1) 20 GHz hybrid amplifiers; (2) 20 GHz monolithic MESFET power amplifiers; (3) Texas Instruments' (TI) 20 GHz variable power amplifier; (4) TI 20 GHz high power amplifier; (5) high efficiency monolithic power amplifiers; (6) GHz high efficiency variable power amplifier; (7) TI 32 GHz monolithic power amplifier performance; (8) design goals for Hughes' 32 GHz variable power amplifier; and (9) performance goals for Hughes' pseudomorphic 60 GHz power amplifier.

  2. Solid state, S-band, power amplifier

    Science.gov (United States)

    Digrindakis, M.

    1973-01-01

    The final design and specifications for a solid state, S-band, power amplifier is reported. Modifications from a previously proposed design were incorporated to improve efficiency and meet input overdrive and noise floor requirements. Reports on the system design, driver amplifier, power amplifier, and voltage and current limiter are included along with a discussion of the testing program.

  3. Solid state ku-band power amplifier

    Science.gov (United States)

    Bowers, H. C.; Lockyear, W. H.

    1972-01-01

    The design, fabrication, and testing of two types of IMPATT diode reflection amplifiers and a transmission amplifier are given. The Ku-band IMPATT diode development is discussed. Circuitry and electrical performance of the final version of the Ku-band amplifier is described. Construction details and an outline and mounting drawing are presented.

  4. low pump power photonic crystal fibre amplifiers

    DEFF Research Database (Denmark)

    Hougaard, Kristian G.; Broeng, Jes; Bjarklev, Anders Overgaard

    2003-01-01

    Designs of low pump power optical amplifiers, based on photonic crystal fibres are presented. The potential of these fibre amplifiers is investigated, and it is demonstrated that such amplifiers may deliver gains of more than 15 dB at 1550 nm with less than 1 mW of optical pump power....

  5. Observation of 3d84d-3d84p soft-x-ray laser emission in high-Z ions isoelectronic to Co I

    International Nuclear Information System (INIS)

    A transition analogous to the strongest 4d-4p nickel-like x-ray laser transition has been observed in cobaltlike ions within the same plasma. Amplified spontaneous emission from Co-like ions has been identified in laser-produced exploding-foil plasmas of Yb and Ta. The Co-like line exhibits similar time history to the Ni-like laser line and has a gain coefficient consistent with a significant Co-like population. The observation of this transition is of interest as fluorinelike analogs to neonlike 3p-3s x-ray lasers have never been seen although they are predicted to have gain

  6. Exploding wire in water – a source of long, dense, hot, and quasi-stable plasma suitable for amplification of EUV/Soft X-ray emission

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Prukner, Václav; Schmidt, Jiří; Frolov, Oleksandr; Štraus, Jaroslav

    Cancún: International and Local Organizing Committees, 2009 - (de Urquijo, J.). s. 117-117 ISBN N. [International Conference on Phenomena in Ionized Gases(ICPIG)/29th./. 12.07.2009-17.07.2009, Cancún] R&D Projects: GA MŠk LA08024; GA AV ČR KAN300100702; GA AV ČR KJB100430702 Institutional research plan: CEZ:AV0Z20430508 Keywords : exploding wire in water * excitation pumping * amplified spontaneous emission Subject RIV: BL - Plasma and Gas Discharge Physics http://www.icpig2009.unam.mx/Misc/AbstractsICPIG2009.pdf

  7. 980-nm all-fiber mode-locked Yb-doped phosphate fiber oscillator based on semiconductor saturable absorber mirror and its amplifier

    Science.gov (United States)

    Li, Ping-Xue; Yao, Yi-Fei; Chi, Jun-Jie; Hu, Hao-Wei; Zhang, Guang-Ju; Liang, Bo-Xing; Zhang, Meng-Meng; Ma, Chun-Mei; Su, Ning

    2016-08-01

    A 980-nm semiconductor saturable absorber mirror (SESAM) mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introduced into the oscillator to obtain a robust and stable mode-locked seed source. When the cavity length is chosen to be 6 m, the oscillator generates an average output power of 3.5 mW and a pulse width of 76.27 ps with a repetition rate of 17.08 MHz. As the cavity length is optimized to short, 4.4-mW maximum output power and 61.15-ps pulse width are produced at a repetition rate of 20.96 MHz. The output spectrum is centered at 980 nm with a narrow spectral bandwidth of 0.13 nm. In the experiment, no undesired amplified spontaneous emission (ASE) nor harmful oscillation around 1030 nm is observed. Moreover, through a two-stage all-fiber-integrated amplifier, an output power of 740 mW is generated with a pulse width of 200 ps. Project supported by the National Natural Science Foundation of China (Grant No. 61205047).

  8. Incomplete spontaneous ureteral disruption

    International Nuclear Information System (INIS)

    Background. The aim of the authors was to present the case of spontaneous partial ureteral rupture during a renal colic, caused by an anorganic concrement in the proximal part of the left ureter, at the level of the transverse processus of L3. Case report. On the excretory urography imaging, the dilatation of the canal system, cups, necks and pyelon, was observed. At the level of the pyeloureteric passage, the contrast medium was leaking. The leakage was found to be extending along the psoas muscle to the pelvis. On the transversal CT imaging scans, the contrast medium was seen along the medial and dorsal part of the perirenal space, and in the distal part, along the psoas muscle to the pelvis. The ureter was imaged from the pyeloureterical rupture to the site of the concrement. No signs of the damage of the renal parenchyma or perirenal bleeding were detected. During surgery, the site of the rupture was found and also a lot of the perirenal and periureteral liquid. After the extraction of the concrement, the suture of the rupture was made. Postoperative urography and CT showed a normal ureteral image. Conclusions. At the spontaneous partial disruption of the ureter, the contrast medium is still seen in the ureter, distally from the site of the rupture and as extravasation along the psoas muscle. (author)

  9. Quantum Spontaneous Stochasticity

    CERN Document Server

    Eyink, Gregory L

    2015-01-01

    The quantum wave-function of a massive particle with small initial uncertainties (consistent with the uncertainty relation) is believed to spread very slowly, so that the dynamics is deterministic. This assumes that the classical motions for given initial data are unique. In fluid turbulence non-uniqueness due to "roughness" of the advecting velocity field is known to lead to stochastic motion of classical particles. Vanishingly small random perturbations are magnified by Richardson diffusion in a "nearly rough" velocity field so that motion remains stochastic as the noise disappears, or classical spontaneous stochasticity, . Analogies between stochastic particle motion in turbulence and quantum evolution suggest that there should be quantum spontaneous stochasticity (QSS). We show this for 1D models of a particle in a repulsive potential that is "nearly rough" with $V(x) \\sim C|x|^{1+\\alpha}$ at distances $|x|\\gg \\ell$ , for some UV cut-off $\\ell$, and for initial Gaussian wave-packet centered at 0. We consi...

  10. NIF/LMJ prototype amplifier mechanical design

    International Nuclear Information System (INIS)

    Amplifier prototypes for the National Ignition Facility and the Laser Megajoule will be tested at Lawrence Livermore National Laboratory. The prototype amplifier, which is an ensemble of modules from LLNL and Centre d'Etudes de Limeil-Valenton, is cassette-based with bottom access for maintenance. A sealed maintenance transfer vehicle which moves optical cassettes between the amplifier and the assembly cleanroom, and a vacuum gripper which holds laser slabs during cassette assembly will also be tested. The prototype amplifier will be used to verify amplifier optical performance, thermal recovery time, and cleanliness of mechanical operations

  11. An Implantable CMOS Amplifier for Nerve Signals

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Lehmann, Torsten

    In this paper, a low noise high gain CMOS amplifier for minute nerve signals is presented. The amplifier is constructed in a fully differential topology to maximize noise rejection. By using a mixture of weak- and strong inversion transistors, optimal noise suppression in the amplifier is achieved....... A continuous-time current-steering offset-compensation technique is utilized in order to minimize the noise contribution and to minimize dynamic impact on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard...

  12. High temperature charge amplifier for geothermal applications

    Science.gov (United States)

    Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.

    2015-12-08

    An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.

  13. Dicke superradiance, Bose-Einstein condensation of photons and spontaneous symmetry breaking

    CERN Document Server

    Vyas, Vivek M; Srinivasan, V

    2016-01-01

    It is shown that the phenomenon of Dicke superradiance essentially occurs due to spontaneous symmetry breaking. Two generalised versions of the Dicke model are studied, and compared with a model that describes photonic Bose-Einstein condensate, which was experimentally realised. In all the models, it is seen that, the occurrence of spontaneous symmetry breaking is responsible for coherent radiation emission.

  14. Spontaneous Coronary Artery Dissection.

    Science.gov (United States)

    Tweet, Marysia S; Gulati, Rajiv; Hayes, Sharonne N

    2016-07-01

    Spontaneous coronary artery dissection is an important etiology of nonatherosclerotic acute coronary syndrome, myocardial infarction, and sudden death. Innovations in the catheterization laboratory including optical coherence tomography and intravascular ultrasound have enhanced the ability to visualize intimal disruption and intramural hematoma associated with SCAD. Formerly considered "rare," these technological advances and heightened awareness suggest that SCAD is more prevalent than prior estimates. SCAD is associated with female sex, young age, extreme emotional stress, or extreme exertion, pregnancy, and fibromuscular dysplasia. The clinical characteristics and management strategies of SCAD patients are different than for atherosclerotic heart disease and deserve specific consideration. This review will highlight recent discoveries about SCAD as well as describe current efforts to elucidate remaining gaps in knowledge. PMID:27216840

  15. Spontaneous wave packet reduction

    International Nuclear Information System (INIS)

    There are taken into account the main conceptual difficulties met by standard quantum mechanics in dealing with physical processes involving macroscopic system. It is stressed how J.A.Wheeler's remarks and lucid analysis have been relevant to pinpoint and to bring to its extreme consequences the puzzling aspects of quantum phenomena. It is shown how the recently proposed models of spontaneous dynamical reduction represent a consistent way to overcome the conceptual difficulties of the standard theory. Obviously, many nontrivial problems remain open, the first and more relevant one being that of generalizing the model theories considered to the relativistic case. This is the challenge of the dynamical reduction program. 43 refs, 2 figs

  16. Spontaneous ovarian hyperstimulation syndrome.

    Science.gov (United States)

    Kasum, Miro; Oresković, Slavko; Jezek, Davor

    2013-06-01

    Spontaneous forms of the ovarian hyperstimulation syndrome (sOHSS) are nearly always reported between 8 and 14 weeks of pregnancy and also with follicle-stimulating hormone (FSH) producing pituitary adenoma. The syndrome has been previously reported in rare instances of increased production of human chorionic gonadotrophin (hCG) such as multiple pregnancies, hydatiforme mole, polycystic ovary disease and elevated concentrations of thyroid-stimulating hormone (TSH) in hypothyreoidism. High levels of these hormones are able to stimulate by natural promiscuous activation the wild-type FSHr, resulting in sporadic presentations of the syndrome. Since 2003, only six different activating FSHr gene mutations have been reported in cases of familial or habitual sOHSS. In addition to five mutations which have been found in the transmembrane helices (Asp567Asn, Asp567Gly, Thr449Ile, Thr449Ala, Ile545Thr), the first germline mutation (c.383C > A, p. Ser 128 Tyr) in the extracelullar domain was identified. All five mutants were abnormally activated by TSH and normal levels of hCG while displaying constitutive activity. In contrast to these mutations, the p.Ser128Tyr mutant displayed an increase in sensitivity only toward hCG. Accordingly, the mutated FSHrs, may be hyperstimulated by the pregnancy-derived hCG or TSH, inducing the occurrence of the syndrome. In the differential diagnosis, malignancy, pregnancy luteoma and hyperreactio luteinalis would have to be excluded. In almost all of the cases the disease regresses spontaneously and could be managed expectantly or conservatively, but with termination of pregnancy or surgery in cases of complications. PMID:23941020

  17. Audio power amplifier design handbook

    CERN Document Server

    Self, Douglas

    2013-01-01

    This book is essential for audio power amplifier designers and engineers for one simple reason...it enables you as a professional to develop reliable, high-performance circuits. The Author Douglas Self covers the major issues of distortion and linearity, power supplies, overload, DC-protection and reactive loading. He also tackles unusual forms of compensation and distortion produced by capacitors and fuses. This completely updated fifth edition includes four NEW chapters including one on The XD Principle, invented by the author, and used by Cambridge Audio. Cro

  18. Cathode-follower power amplifier

    International Nuclear Information System (INIS)

    In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms

  19. High power RF solid state power amplifier system

    Science.gov (United States)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

    2011-01-01

    A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

  20. Self-amplifying Hawking radiation and its background: a numerical study

    CERN Document Server

    Steinhauer, Jeff

    2016-01-01

    We numerically study an analogue black hole with two horizons with similar parameters to a recent experiment. We find that the Hawking radiation exists on a background which contains a density oscillation, a zero-frequency ripple. The Hawking radiation evolves from spontaneous to self-amplifying, while the background ripple grows steadily with no qualitative change. It is seen that the self-amplifying Hawking radiation has a non-zero frequency. The background ripple appears even before the inner horizon is created, in contrast to predictions. This work is in agreement with the recent observation of self-amplifying Hawking radiation, and explains some of the features seen. In contrast to recent works, our study differentiates between the Hawking radiation observed, and the evolution of the background.

  1. Pregnancy outcome following spontaneous abortions

    Directory of Open Access Journals (Sweden)

    Swati Agrawal

    2015-12-01

    Conclusions: Previous history of spontaneous abortion is associated with adverse pregnancy outcome. There is increased risk of abortion, preterm delivery, need for caesarean sections and fetal loss in cases of previous spontaneous abortions. These complications and fetal loss can be reduced by booking the patients and giving due antenatal care. [Int J Reprod Contracept Obstet Gynecol 2015; 4(6.000: 1891-1893

  2. Emergency Surgery for Spontaneous Hemopneumothorax

    International Nuclear Information System (INIS)

    Emergency management of spontaneous hemopneumothorax patients was retrospectively analysed in this study. From November 2009 to August 2012, 221 patients with spontaneous pneumothorax were treated in the thoracic surgery clinic. Among them, 9 (4.07%) were diagnosed with spontaneous hemopneumothorax. Chest X-ray and computed tomography were the diagnostic tools. Emergency thoracotomy was performed for 7 of 9 patients because of massive hemothorax and continuous bleeding from the chest tube. Massive hematoma was documented in 2 of 7 patients at tomography. Bridging veins and torn pleural adhesion between parietal and visceral pleura were the source of bleeding determined at thoracotomy. Hematoma evacuation, resection of bullae, ligation of pleural adhesions and apical pleurectomy were performed. Spontaneous hemopneumothorax is an emergency due to massive hemorrhage and hematoma formation. Early surgical treatment is recommended for patients with spontaneous hemopneumothorax. (author)

  3. Thermal Radio Emission as Incoherent Induced Radiation

    OpenAIRE

    Prigara, Fedor V.

    2001-01-01

    The synchrotron interpretation of radio emission from various astrophysical objects encounters the essential difficulties . These difficulties may be overcome in a new theory of thermal radio emission of non-uniform gas which is based on a stimulated character of thermal radio emission following from the relations between Einstein?s coefficients for spontaneous and induced emission of radiation .

  4. Spontaneous fission half-lives and their systematics

    International Nuclear Information System (INIS)

    Spontaneous fission is a phenomenon exhibited by heavy nuclei, which can be a major mode of decay of nuclei of elements heavier than thorium and can be a determining factor in their stability. For purposes of this paper, spontaneous fission will be considered a process in which a nucleus breaks up into two approximately equal parts. The emission of light nuclei or heavy ions such as 12C, 16O, or 32S will not be considered. This radioactive decay mode is often much smaller than the spontaneous fission decay mode, although this is not true in all cases. Barwick noted that this might indicate that the assumed half-life for spontaneous fission of some older experiments might be partially due to heavy fragment radioactivity. Other than taking note of this potential correction to spontaneous fission half-lives, this decay mode of heavy fragment radioactivity will be ignored. Excited states of some heavy nuclei may decay via spontaneous fission. These so-called fission isomers will not be discussed here. Electron capture (EC) or beta-delayed fission is a process in which prompt fission of a sufficiently excited daughter state occurs following population by EC or beta decay. The fission activity will appear to decay with the half-life of the parent and was earlier confused in some cases with SF. This process has been discussed in detail in a review and will not be considered in this paper

  5. High-efficiency solid state power amplifier

    Science.gov (United States)

    Wallis, Robert E. (Inventor); Cheng, Sheng (Inventor)

    2005-01-01

    A high-efficiency solid state power amplifier (SSPA) for specific use in a spacecraft is provided. The SSPA has a mass of less than 850 g and includes two different X-band power amplifier sections, i.e., a lumped power amplifier with a single 11-W output and a distributed power amplifier with eight 2.75-W outputs. These two amplifier sections provide output power that is scalable from 11 to 15 watts without major design changes. Five different hybrid microcircuits, including high-efficiency Heterostructure Field Effect Transistor (HFET) amplifiers and Monolithic Microwave Integrated Circuit (MMIC) phase shifters have been developed for use within the SSPA. A highly efficient packaging approach enables the integration of a large number of hybrid circuits into the SSPA.

  6. YANG-MILLS FIELD AMPLIFIER

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2015-09-01

    Full Text Available The article presents a project of the Yang-Mills amplifier. Amplifier model is a multilayer spherical shell with increasing density towards the center. In the center of the amplifier is the core of high-density material. It is shown that in such a system, the amplitude of the Yang-Mills waves rises from the periphery to the center of several orders of magnitude. The role of the Yang-Mills field in the processes occurring in the nuclei of galaxies, stars and planets is discussed. The data modeling to strengthen the Yang-Mills field in the bowels of the planet, with an atomic explosion, and in some special devices such as the voltaic pile. To describe the mechanism of amplification chromodynamics field used as accurate results in Yang-Mills theory and numerical models developed based on an average and the exact equations as well. Among the exact solutions of the special role played by the centralsymmetric metric describing the contribution of the Yang-Mills field in the speed of recession of galaxies. Among the approximate numerical models can be noted the eight-scalar model we have developed for the simulation of non-linear color oscillations and chaos in the Yang-Mills theory. Earlier models were investigated spatio-temporal oscillations of the YangMills theory in the case of three and eight colors. The results of numerical simulation show that the nonlinear interaction does not lead to a spatial mixing of colors as it might be in the case of turbulent diffusion. Depending on the system parameters there is a suppression of the amplitude of the oscillations the first three by five colors or vice versa. The kinetic energy fluctuations or shared equally between the color components, or dominated by the kinetic energy of repressed groups of colors. In the present study, we found that amplification chromodynamic field leads to a sharp increase in the amplitude of the suppressed color, which can lead to an increase in entropy, excitation of nuclear

  7. Spontaneous breaking of supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Zumino, B.

    1981-12-01

    There has been recently a revival of interest in supersymmetric gauge theories, stimulated by the hope that supersymmetry might help in clarifying some of the questions which remain unanswered in the so called Grand Unified Theories and in particular the gauge hierarchy problem. In a Grand Unified Theory one has two widely different mass scales: the unification mass M approx. = 10/sup 15/GeV at which the unification group (e.g. SU(5)) breaks down to SU(3) x SU(2) x U(1) and the mass ..mu.. approx. = 100 GeV at which SU(2) x U(1) is broken down to the U(1) of electromagnetism. There is at present no theoretical understanding of the extreme smallness of the ratio ..mu../M of these two numbers. This is the gauge hierarchy problem. This lecture attempts to review the various mechanisms for spontaneous supersymmetry breaking in gauge theories. Most of the discussions are concerned with the tree approximation, but what is presently known about radiative correction is also reviewed.

  8. Spontaneous bacterial peritonitis

    Institute of Scientific and Technical Information of China (English)

    Anastasios Koulaouzidis; Shivaram Bhat; Athar A Saeed

    2009-01-01

    Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis,albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis.Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the 'tap-toshot' time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind proinflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation.

  9. [Lazarus phenomenon: spontaneous resuscitation].

    Science.gov (United States)

    Casielles García, J L; González Latorre, M V; Fernández Amigo, N; Guerra Vélz, A; Cotta Galán, M; Bravo Capaz, E; de las Mulas Béjar, M

    2004-01-01

    A 94-year-old woman undergoing surgery for simple repair of a duodenal perforation experienced a sudden massive hemorrhage (1500 mL) when the duodenum was separated from adjacent structures. Hemodynamic stability was re-established when fluids were replaced. After the abdominal wall was closed, increased amplitude of the QRS wave was observed and heart rate slowed until there was no pulse. Electromechanical dissociation (EMD) was diagnosed and cardiopulmonary resuscitation was started. When EMD persisted after 40 minutes, resuscitative measures were stopped and the ventilator was disconnected, though orotracheal intubation and arterial and electrocardiographic monitoring were maintained. After 2 or 3 minutes, heart rhythm restarted spontaneously and arterial pressure waves reappeared on the monitor. The patient progressed well for 72 hours, after which she developed septic shock and multiorgan failure, dying 18 days later. The Lazarus phenomenon may be more common than the medical literature would indicate, possibly because a large gap in our understanding of the pathophysiology of the phenomenon underlies anecdotes about "miracles". As we wait for adequate international consensus on a protocol for monitoring the withdrawal of resuscitative measures, we should act prudently before definitively certifying death. The case we report occurred during a surgical intervention in which the patient had received general anesthesia. We believe that the causes that might explain the Lazarus phenomenon are quite different in that context than they would be in a nonsurgical setting, such that it would be useful to create a national database to keep a record of such intraoperative events. PMID:15495638

  10. Spontaneous subgaleal aerocele.

    Science.gov (United States)

    Ibe, M O N; Onu, D O; Igwe, N N

    2014-01-01

    Apart from reporting about a case of spontaneous subgaleal aerocele this paper looks at the possible causes and management also. A 35-year-old Igbo-Nigerian female, about 4 weeks post-natal, with a 10-month old steadily and gradually enlarging mass around the back of her head, including both temporal regions was referred to us. Plain skull radiographs showed air in this mass. Needle puncture produced air leading to immediate and complete flattening of the lesion. A few hours after this procedure while still in the hospital premises, she had generalized convulsions, for which she was hospitalized and treated. With no further attacks, her request for discharge the following day was granted. At the next visit, 7 days later, there was a re-accumulation, which was treated the same way as previously and with the same result. She has not reported back since then, though she was advised to visit us again in 7 day-time. This lesion should be considered when masses on the head are presented. Our health institutions should have adequate investigative facilities. PMID:24553041

  11. Effect of spontaneous polarization on thermoemission of lithium niobate

    International Nuclear Information System (INIS)

    The effect of spontaneous polarization on thermionic and ion emission of lithium niobate is investigated. The temperature dependences are given of electron and ion currents of samples whose surfaces are perpendicular or parallel to the polar axis. The work function is determined by the experimetal dependences. It is established that the work function of lithium niobate, neglecting ferroelectric bending of bands, is the same for the crystallographic directions chosen and is equal to 2.2+-0.1 eV. Spontaneous polarization exerts an appreciable effect on the emission properties of surfaces perpendicular to the polar axis and does not affect the emission of surfaces parallel to it. The change in work function due to ferroelectric bending of bands may be as high as 1.0 eV

  12. Enhanced Gain in Photonic Crystal Amplifiers

    DEFF Research Database (Denmark)

    Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann;

    2012-01-01

    study of a 1 QW photonic crystal amplifier. Net gain is achieved which enables laser oscillation in photonic crystal micro cavities. The ability to freely tailor the dispersion in a semiconductor optical amplifier makes it possible to raise the optical gain considerably over a certain bandwidth. These...... results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....

  13. Reflection amplifiers in self-regulated learning

    OpenAIRE

    Verpoorten, Dominique

    2012-01-01

    Verpoorten, D. (2012). Reflection amplifiers in self-regulated learning. Doctoral thesis. November, 9, 2012, Heerlen, The Netherlands: Open Universiteit (CELSTEC). Datawyse / Universitaire Pers Maastricht.

  14. Dynamics of Soliton Cascades in Fiber Amplifiers

    CERN Document Server

    Arteaga-Sierra, F R; Agrawal, Govind P

    2016-01-01

    We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of input pulses.

  15. Ping-pong auto-zero amplifier with glitch reduction

    Science.gov (United States)

    Larson, Mark R.

    2008-01-22

    A ping-pong amplifier with reduced glitching is described. The ping-pong amplifier includes a nulling amplifier coupled to a switching network. The switching network is used to auto-zero a ping amplifier within a ping-pong amplifier. The nulling amplifier drives the output of a ping amplifier to a proper output voltage level during auto-zeroing of the ping amplifier. By being at a proper output voltage level, glitches associated with transitioning between a ping amplifier and a pong amplifier are reduced or eliminated.

  16. Linearisation of RF Power Amplifiers

    DEFF Research Database (Denmark)

    Nielsen, Per Asbeck

    2001-01-01

    linearisation systems with focus on polar modulation feedback, and a chip oriented part focusing on integrating of separate building blocks of the system on a chip. The system oriented part of this thesis deals with analog feedback linearisation systems. The Polar modulation feedback system is compared with the...... more traditional Cartesian modulation feedback system in terms of loop settlement and dependencies between the feedback signals. A method to calculate the distortion functions of the linearisation system (AM/AM and AM/PM)based on the distortion functions of the power amplifier is presented. Also the...... polar loop architecture and it’s suitability to modern digital transmitters is discussed. A proposal of an architecture that is suitable for digital transmitters, which means that it has an interface to the digital back-end, defined by low-pass signals in polar form, is presented. Simulation guidelines...

  17. Transverse pumped laser amplifier architecture

    Science.gov (United States)

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

    2013-07-09

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  18. Regime for a Self-ionizing Raman Laser Amplifier

    International Nuclear Information System (INIS)

    Backward Raman amplification and compression at high power might occur if a long pumping laser pulse is passed through a plasma to interact resonantly with a counter-propagating short seed pulse [V.M. Malkin, et al., Phys. Rev. Lett. 82 (1999) 4448-4451]. One critical issue, however, is that the pump may be unacceptably depleted due to spontaneous Raman backscatter from intrinsic fluctuations in the amplifying plasma medium prior to its useful interaction with the seed. Premature backscatter may be avoided, however, by employing a gaseous medium with pump intensities too low to ionize the medium, and using the intense seed to produce the plasma by rapid photoionization as it is being amplified [V.M. Malkin, et al., Phys. Plasmas (2001)]. In addition to allowing that only rather low power pumps be used, photoionization introduces a damping of the short pulse which must be overcome by the Raman growth rate for net amplification to occur. The parameter space of gas densities, laser wavelengths, and laser intensities is surveyed to identify favorable regimes for this effect. Output laser intensities of 10(superscript ''17'') W/cm(superscript ''2'') for 0.5 mm radiation are found to be feasible for such a scheme using a pump of 10(superscript ''13'') W/cm(superscript ''2'') and an initial seed of 5 x 10(superscript ''14'') W/cm(superscript ''2'') over an amplification length of 5.6 cm in hydrogen gas

  19. Regime for a self-ionizing Raman laser amplifier

    International Nuclear Information System (INIS)

    Backward Raman amplification and compression at high power might occur if a long pumping laser pulse is passed through a plasma to interact resonantly with a counter-propagating short seed pulse [V. M. Malkin et al., Phys. Rev. Lett. 82, 4448-4451 (1999)]. One critical issue, however, is that the pump may be unacceptably depleted due to spontaneous Raman backscatter from intrinsic fluctuations in the amplifying plasma medium prior to its useful interaction with the seed. Premature backscatter may be avoided, however, by employing a gaseous medium with pump intensities too low to ionize the medium and using the intense seed to produce the plasma by rapid photoionization as it is being amplified [V. M. Malkin et al., Phys. Plasmas 8, 4698-4699 (2001)]. In addition to allowing that only rather low power pumps be used, photoionization introduces a damping of the short pulse which must be overcome by the Raman growth rate for net amplification to occur. The parameter space of gas densities, laser wavelengths, and laser intensities is surveyed to identify favorable regimes for this effect. Output laser intensities of 2x1017 W/cm2 for 0.5 μm radiation are found to be feasible for such a scheme using a pump of 1x1013 W/cm2 and an initial seed of 5x1014 W/cm2 over an amplification length of 5.6 cm in hydrogen gas

  20. Process of spontaneous combustion of solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Postrzednik, S.; Bialecki, R.; Nowak, A. (Politechnika Slaska, Gliwice (Poland))

    1988-01-01

    Reviews literature on coal spontaneous combustion and oxidation. The following aspects are discussed: low-temperature oxidation, medium and high-temperature oxidation, theories of spontaneous coal combustion (bacteria theory, phenol theory, water-coal system theory, water adsorption theory), factors that influence spontaneous combustion (coal rank, petrology, porosity, moisture content, storage method, storage temperature, air circulation, macrostructure and geometry of the system for storage of coal), effects of mineral content on coal hazards of spontaneous combustion, physicochemical phenomena that influence spontaneous combustion, laboratory investigations into spontaneous combustion, experimental methods used in laboratory investigations, forecasting energy effects of spontaneous combustion, mathematical models of coal spontaneous combustion. 94 refs.