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Sample records for optically pumped trions

  1. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  2. Velocity selective optical pumping

    OpenAIRE

    Aminoff, C. G.; Pinard, M.

    1982-01-01

    We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of co...

  3. Nonlinear Raman Shift Induced by Exciton-to-Trion Transformation in Suspended Trilayer MoS2

    CERN Document Server

    Taghinejad, Hossein; Tarasov, Alexey; Tsai, Meng-Yen; Hosseinnia, Amir H; Campbell, Philip M; Eftekhar, Ali A; Vogel, Eric M; Adibi, Ali

    2015-01-01

    Layered two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have recently attracted remarkable attention because of their unique physical properties. Here, we use photoluminescence (PL) and Raman spectroscopy to study the formation of the so- called trions in a synthesized freestanding trilayer MoS2. A trion is a charged quasi-particle formed by adding one electron or hole to a neutral exciton (a bound electron-hole pair). We demonstrate accurate control over the transformation of excitons to trions by tuning the power of the optical pump (laser). Increasing the power of the excitation laser beyond a certain threshold (~ 4 mW) allows modulation of trion-to-exciton PL intensity ratio as well as the spectral linewidth of both trions and excitons. Via a systematic and complementary Raman analysis we disclose a strong coupling between laser induced exciton-to-trion transformation and the characteristic phononic vibrations of MoS2. The onset of such an optical transformation corresponds to the ...

  4. Fast and high-fidelity optical initialization of spin state of an electron in a semiconductor quantum dot using light-hole-trion states

    Science.gov (United States)

    Kumar, Parvendra; Nakajima, Takashi

    2016-07-01

    We theoretically show that under the Faraday geometry fast and high-fidelity optical initialization of electron spin (ES) state in a semiconductor quantum dot (SQD) can be realized by utilizing the light-hole (LH)-trion states. Initialization is completed within the time scale of ten nanoseconds with high fidelity, and the initialization laser pulse can be linearly, right-circularly, or left-circularly polarized. Moreover, we demonstrate that the time required for initialization can be further shortened down to a few hundreds of picoseconds if we introduce a pillar-microcavity to promote the relaxation of a LH-trion state towards the desired ES state through the Purcell effect. We also clarify the role of heavy-hole and light-hole mixing induced transitions on the fidelity of ES state initialization.

  5. Stability of singlet and triplet trions in carbon nanotubes

    DEFF Research Database (Denmark)

    Rønnow, Troels Frimodt; Pedersen, Thomas Garm; Cornean, Horia

    2009-01-01

    We investigate singlet and triplet trion states in semiconducting carbon nanotubes using a one-dimensional model. It is concluded that singlet trion states in bind up to 13.5% stronger than exciton states, and that they lower the optical transition energy with up to 50% of the tight binding band ...

  6. Magnetic-field control of photon echo from the electron-trion system in a CdTe quantum well: shuffling coherence between optically accessible and inaccessible states.

    Science.gov (United States)

    Langer, L; Poltavtsev, S V; Yugova, I A; Yakovlev, D R; Karczewski, G; Wojtowicz, T; Kossut, J; Akimov, I A; Bayer, M

    2012-10-12

    We report on magnetic field-induced oscillations of the photon echo signal from negatively charged excitons in a CdTe/(Cd,Mg)Te semiconductor quantum well. The oscillatory signal is due to Larmor precession of the electron spin about a transverse magnetic field and depends sensitively on the polarization configuration of the exciting and refocusing pulses. The echo amplitude can be fully tuned from the maximum down to zero depending on the time delay between the two pulses and the magnetic-field strength. The results are explained in terms of the optical Bloch equations accounting for the spin level structure of electrons and trions.

  7. Optical Pumping of Molecular Gases

    Science.gov (United States)

    1976-04-01

    in Hg, excimer system. IV. OPTICALLY PUMPED Na Ř The details of our optical pumping studies of Na2 are presented in Appendix I. The study showed that...inversitot In IM -Second set of linesn have. tentatively been Identified ats D asid A btuu~t-sa A-band tratsitiwts termiuiatitig, oilt*n 3,4,5 for J0 TO HELIUM

  8. Optical pumping and xenon NMR

    Energy Technology Data Exchange (ETDEWEB)

    Raftery, M. Daniel [Univ. of California, Berkeley, CA (United States)

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  9. Optical pumping and xenon NMR

    Energy Technology Data Exchange (ETDEWEB)

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  10. Trion valley coherence in monolayer semiconductors

    Science.gov (United States)

    Hao, Kai; Xu, Lixiang; Wu, Fengcheng; Nagler, Philipp; Tran, Kha; Ma, Xin; Schüller, Christian; Korn, Tobias; MacDonald, Allan H.; Moody, Galan; Li, Xiaoqin

    2017-06-01

    The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the superposition of electron-hole pairs at opposite valleys) in monolayer transition metal dichalcogenides (TMDs) provide a critical step towards control of this quantum degree of freedom. The charged exciton (trion) in TMDs is an intriguing alternative to the neutral exciton for control of valley pseudospin because of its long spontaneous recombination lifetime, its robust valley polarization, and its coupling to residual electronic spin. Trion valley coherence has however been unexplored due to experimental challenges in accessing it spectroscopically. In this work, we employ ultrafast 2D coherent spectroscopy to resonantly generate and detect trion valley coherence in monolayer MoSe2 demonstrating that it persists for a few-hundred femtoseconds. We conclude that the underlying mechanisms limiting trion valley coherence are fundamentally different from those applicable to exciton valley coherence.

  11. Actively Pumped Faraday Optical Filter

    Science.gov (United States)

    1996-04-30

    Richard I. Billmers Vincent M. Contarino David M. Allocca Martin F. Squicciarini William J. Scharpf 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...States Patent [i9] Billmers et al. iiiiiiifflimi iilliiiiiii US005513032A [ii] Patent Number: [45] Date of Patent: 5,513,032 Apr. 30, 1996...54] ACTIVELY PUMPED FARADAY OPTICAL FILTER [75] Inventors: Richard I. Billmers , Bensalem; Vincent M. Contarino, Warrington; David M

  12. Coherent optical pumping of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pfister, M.; Dupertuis, M.A. [Inst. de Micro- et Optoelectronique, Lausanne (Switzerland). Dept. de Physique

    1995-01-01

    The influence of coherent optical pumping in semiconductor lasers is investigated theoretically. In particular the mathematical conditions under which an optically pumped system behaves like an electrically (incoherently) pumped system are derived. The authors show that it is practically impossible to reach the interesting regime where coherent effects are important because of the inherent constraints to absorb photons at the pump frequency and to reach threshold gain at the lasing frequency. The effects of changing the temperature and of reduced dimensionality are discussed.

  13. Trion-Induced Negative Photoconductivity in Monolayer MoS2

    Science.gov (United States)

    Lui, C. H.; Frenzel, A. J.; Pilon, D. V.; Lee, Y.-H.; Ling, X.; Akselrod, G. M.; Kong, J.; Gedik, N.

    2014-10-01

    Optical excitation typically enhances electrical conduction and low-frequency radiation absorption in semiconductors. We, however, observe a pronounced transient decrease of conductivity in doped monolayer molybdenum disulfide (MoS2), a two-dimensional (2D) semiconductor, using ultrafast optical-pump terahertz-probe spectroscopy. In particular, the conductivity is reduced to only 30% of its equilibrium value at high pump fluence. This anomalous phenomenon arises from the strong many-body interactions in the 2D system, where photoexcited electron-hole pairs join the doping-induced charges to form trions, bound states of two electrons and one hole. The resultant increase of the carrier effective mass substantially diminishes the conductivity.

  14. Diode-pumped optical parametric oscillator.

    Science.gov (United States)

    Geiger, A R; Hemmati, H; Farr, W H; Prasad, N S

    1996-02-01

    Diode-pumped optical parametric oscillation has been demonstrated for the first time to our knowledge in a single Nd:MgO:LiNbO(3) nonlinear crystal. The crystal is pumped by a semiconductor diode laser array at 812 nm. The Nd(3+) ions absorb the 812-nm radiation to generate 1084-nm laser oscillation. On internal Q switching the 1084-nm radiation pumps the LiNbO(3) host crystal that is angle cut at 46.5 degrees and generates optical parametric oscillation. The oscillation threshold that is due to the 1084-nm laser pump with a pulse length of 80 ns in a 1-mm-diameter beam was measured to be approximately 1 mJ and produced 0.5-mJ output at 3400-nm signal wavelength.

  15. Polarization chaos in an optically pumped laser.

    Science.gov (United States)

    Serrat, C; Kul'minskii, A; Vilaseca, R; Corbalán, R

    1995-06-15

    We study the steady-state and dynamic behavior of an optically pumped J = 0 ? J = 1 ? J = 0 laser operating with an isotropic ring cavity and an axial magnetic field. The gain anisotropy induced by a linearly polarized pump-laser f ield leads, in the steady state, to locking of the two circularly polarized components of the laser field, which acquires a linear polarization parallel to that of the pump field. In the presence of laser intensity instabilities, however, locking does not occur, and polarization instabilities appear. For the f irst time to our knowledge, polarization chaos has been found in a laser system.

  16. Optically-electrically pumped THz source

    Science.gov (United States)

    Haji-Saeed, Bahareh; Khoury, Jed; Buchwald, Walter; Woods, Charles; Wentzell, Sandra; Krejca, Brian; Kierstead, John

    2010-08-01

    In this paper, we propose a design for a widely tunable solid-state optically and electrically pumped THz source based on the Smith-Purcell free-electron laser. Our design consists of a thin dielectric layer sandwiched between an upper corrugated structure and a lower layer of thin metal, semiconductor, or high electron mobility material. The lower layer is for current streaming, which replaces the electron beam in the Smith-Purcell free-electron laser design. The upper layer consists of two micro-gratings for optical pumping, and a nano-grating to couple with electrical pumping in the lower layer. The optically generated surface plasmon waves from the upper layer and the electrically induced surface plasmon waves from the lower layer are then coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  17. High sensitivity optically pumped quantum magnetometer.

    Science.gov (United States)

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  18. Excitons and trions in single and vertically coupled quantum dots under an electric field

    Science.gov (United States)

    Zhai, Li-Xue; Wang, Yan; An, Zhong

    2017-08-01

    We present a theoretical study of the exciton (X0), the positive and negative trions (X+ and X-) in single and vertically coupled configurations of self-assembled InGaAs quantum dots under an electric field. The quantum states of X0, X+ and X- have been investigated using a quasi-one-dimensional (Q1D) model within the effective-mass approximation. For the single quantum dots, the electric-field dependent energy levels and the average inter-particle distances for the exciton and trions have been calculated. For the coupled quantum dots, the ground and the excited states for X0, X+ and X- have also been calculated and discussed. It is found that either the hole or the electron can be tuned into resonance states by the electric field and that the transition energy spectra for both trions consequently show crossing and anticrossing patterns. The recombination probabilities of the exciton and trion optical transitions are also calculated. The theoretical results have been compared with previously reported photoluminescence data and qualitative agreement is obtained. The trion conditional wave functions are also plotted under different electric field intensities, and it is found that a molecular orbital can be formed at a critical electric field intensity. The evolution of the energy levels of the trions in coupled quantum dots can be explained by the interplay of particle transfer and the electric field.

  19. Femtosecond study of the interplay between excitons, trions, and carriers in (Cd,Mn)Te quantum wells.

    Science.gov (United States)

    Płochocka, P; Kossacki, P; Maślana, W; Cibert, J; Tatarenko, S; Radzewicz, C; Gaj, J A

    2004-04-30

    We study the absorption by neutral excitons and positively charged excitons (trions) following a femtosecond, circularly polarized, resonant pump pulse. Three populations are involved: free holes, excitons, and trions, all exhibiting transient spin polarization. In particular, a polarization of the gas of free holes is created by the formation of trions. The evolution of these populations is described, including spin flip and trion formation. We evaluate the contributions of phase space filling and spin-dependent screening. We propose a new explanation of the oscillator strength stealing phenomena observed in doped quantum wells, based on the screening of neutral excitons by charge carriers. We have also found that binding holes into charged excitons excludes them from the interaction with the rest of the system, so that oscillator strength stealing is partially blocked.

  20. Grating THz laser with optical pumping

    Science.gov (United States)

    Khoury, Jed; Haji-saeed, Bahareh; Woods, Charles; Kierstead, John

    2010-04-01

    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  1. An Atom Trap Relying on Optical Pumping

    CERN Document Server

    Bouyer, P; Dahan, M B; Michaud, A; Salomon, C; Dalibard, J

    1994-01-01

    We have investigated a new radiation pressure trap which relies on optical pumping and does not require any magnetic field. It employs six circularly polarized divergent beams and works on the red of a $J_{g} \\longrightarrow J_{e} = J_{g} + 1$ atomic transition with $J_{g} \\geq 1/2$. We have demonstrated this trap with cesium atoms from a vapour cell using the 852 nm $J_{g} = 4 \\longrightarrow J_{e} = 5$ resonance transition. The trap contained up to $3 \\cdot 10^{7}$ atoms in a cloud of $1/\\sqrt{e}$ radius of 330 $\\mu$m.

  2. Heat pumping with optically driven excitons

    CERN Document Server

    Gauger, Erik M

    2010-01-01

    We present a theoretical study showing that an optically driven excitonic two-level system in a solid state environment acts as a heat pump by means of repeated phonon emission or absorption events. We derive a master equation for the combined phonon bath and two-level system dynamics and analyze the direction and rate of energy transfer as a function of the externally accessible driving parameters. We discover that if the driving laser is detuned from the exciton transition, cooling the phonon environment becomes possible.

  3. Velocity selective optical pumping resonance sign reversal

    Science.gov (United States)

    Krasteva, A.; Slavov, D.; Todorov, G.; Cartaleva, S.

    2013-03-01

    We report experimental and theoretical examinations of the peculiarities in Velocity Selective Optical Pumping (VSOP) resonance behavior at open and closed hyperfine transition spectra of Cs atoms (on the D2 line), confined in optical cell with thickness L = 6λ, where λ = 852 nm. For linear and circular polarizations of the irradiating light, open transitions exhibit reduced absorption (fluorescence) VSOP resonances whose contrast increases with atomic concentration and light intensity. However, in case of closed transition the situation is different, the enhanced absorption (fluorescence) VSOP resonance reverses its sign with the atomic concentration and light intensity. Theoretical analysis based on the density matrix formalism, taking into account the statistical tensors describing atomic population and longitudinal alignment, shows that the VSOP resonance sign reversal at the closed transition can be attributed to the efficiency reduction of population transfer by the spontaneous decay with atomic source temperature.

  4. The Optically Pumped Cs Frequency Standard at the NRLM

    Science.gov (United States)

    1987-12-01

    References 1. J.L. Picqu6, "Hyperfine optical pumping of a cesium atomic beam, and applications," Metrologia, vo1.13, pp.115-119, 1977. 2. M. Arditi and... Arditi , "A caesium beam atomic clock with laser optical pumping, as a potential frequency standard," Metrologia, vo1.18, pp.59-66, 1982. 4. G

  5. Unidirectionality of an optically pumped far infrared ring laser

    Science.gov (United States)

    Matsushima, Kyoji; Higashida, Noriyoshi; Sokabe, Noburu; Ariyasu, Tomio

    1995-02-01

    An experimental and theoretical investigation has been made on the unidirectional operation of an optically pumped far infrared ring laser. A ring laser operating on the 119 μm line of CH 3OH experiences reversal of output direction in either case of (a) the pump frequency being tuned across the line center of the infrared pump transition or (b) the fir cavity being tuned across the far infrared line center. A model based on two-mode laser theory predicts the output directionality of the optically pumped fir ring laser.

  6. Threshold ratios for molecular lasers with optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Churakou, U.V.

    1976-01-01

    A series of relationships was obtained for threshold characteristics of high pressure molecular lasers with optical pumping. The threshold pumping density increases in proportion to the square of the active medium's pressure. The minimum value of threshold pumping corresponds to the maximum of the Boltzmann distribution function for rotating sublevels both in the pumping channel and in generation. A weak or strong relationship was observed between the threshold impulse energy and the pressure that is caused by fluctuative relaxation of the upper laser level for various relationships between the intensity of the pumping impulse, pressure and loss coefficient.

  7. Molecular system generation with strong resonance optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Churakov, V.V.

    1977-03-01

    A study was made of molecular system generation modulated by three oscillating levels with a rotating structure with strong resonance optical pumping. Molecular behavior of the active medium is described by equations for the density matrix. The relationship between the amplification coefficient and pressure at various pumping intensities was examined. In approaching the assigned pumping field, an examination was made of how the generation field is affected by the volumetric density of the pumping energy, partial pressure of the buffer gas and frequency difference in the pumping channel.

  8. Synchronous Spin-Exchange Optical Pumping

    CERN Document Server

    Korver, Anna; Bulatowicz, Mike; Walker, Thad

    2015-01-01

    We describe a new approach to precision NMR with hyperpolarized gases designed to mitigate NMR frequency shifts due to the alkali spin exchange field. The electronic spin polarization of optically pumped alkali atoms is square-wave modulated at the noble-gas NMR frequency and oriented transverse to the DC Fourier component of the NMR bias field. Noble gas NMR is driven by spin-exchange collisions with the oscillating electron spins. On resonance, the time-average torque from the oscillating spin-exchange field produced by the alkali spins is zero. Implementing the NMR bias field as a sequence of alkali 2$ \\pi $-pulses enables synchronization of the alkali and noble gas spins despite a 1000-fold discrepancy in gyromagnetic ratio. We demonstrate this method with Rb and Xe, and observe novel NMR broadening effects due to the transverse oscillating spin exchange field. When uncompensated, the spin-exchange field at high density broadens the NMR linewidth by an order of magnitude, with an even more dramatic suppre...

  9. Magnetoencephalography with Optically Pumped Atomic Magnetometers

    Science.gov (United States)

    Schwindt, Peter; Colombo, Anthony; Jau, Yuan-Yu; Carter, Tony; Berry, Christopher; Young, Amber; McKay, Jim; Weisend, Michael

    2015-05-01

    We are working to develop a 36-channel array of optically pumped atomic magnetometers (AMs) to perform magnetoencephalography (MEG) with the goal of localizing magnetic sources within the human brain. The 36-channel array will consist of nine 4-channel sensor modules where the channels within each sensor will be spaced by 18 mm and each sensor will cover a 40 mm by 40 mm area of the head. In a previous 4-channel AM prototype, we demonstrated the measurement of evoked responses in both the auditory and somatosensory cortexes. This prototype had a 5 fT/Hz1/2 sensitivity. In the current version of the AM under development we are maintaining the previous sensitivity while implementing several improvements, including increasing the bandwidth from 20 Hz to more than 100 Hz, reducing the separation of the active volume of the AM from exterior of the sensor from 25 mm to 10 mm or less, and reducing the active sensor volume by a factor >10 to ~15 mm3. We will present results on the performance of our most recent AM prototype and progress toward developing a complete MEG system including a person-sized magnetic shield to provide a low-noise magnetic environment for MEG measurements.

  10. Relaxation of quadrupole orientation in an optically pumped alkali vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E.; Tornos, J.

    1985-04-01

    The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.

  11. Electrical versus optical pumping of quantum dot amplifiers

    DEFF Research Database (Denmark)

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

    2001-01-01

    The influence of the pumping mechanism for the dynamical properties of quantum dot amplifiers is investigated for 10, 40 and 160 GHz signals. A fast response is predicted in the case of optical pumping in the wetting layer (WL). The combination of fast relaxation and capture times and the presence...

  12. Performance Analysis Of Single-Pumped And Dual-Pumped Parametric Optical Amplifier

    Directory of Open Access Journals (Sweden)

    Sandar Myint

    2015-06-01

    Full Text Available Abstract In this study we present a performance analysis of single-pumped and dual- pumped parametric optical amplifier and present the analysis of gain flatness in dual- pumped Fiber Optical Parametric Amplifier FOPA based on four-wave mixing FWM. Result shows that changing the signal power and pump power give the various gains in FOPA. It is also found out that the parametric gain increase with increase in pump power and decrease in signal power. .Moreover in this paper the phase matching condition in FWM plays a vital role in predicting the gain profile of the FOPAbecause the parametric gain is maximum when the total phase mismatch is zero.In this paper single-pumped parametric amplification over a 50nm gain bandwidth is demonstrated using 500 nm highly nonlinear fiber HNLF and signal achieves about 31dB gain. For dual-pumped parametric amplification signal achieves 26.5dB gains over a 50nm gain bandwidth. Therefore dual-pumped parametric amplifier can provide relatively flat gain over a much wider bandwidth than the single-pumped FOPA.

  13. Magnetoluminescence from trion and biexciton in type-II quantum dot

    Directory of Open Access Journals (Sweden)

    Okuyama Rin

    2011-01-01

    Full Text Available Abstract We theoretically investigate optical Aharonov-Bohm (AB effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e. PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc

  14. Spiral intensity patterns in the internally pumped optical parametric oscillator

    DEFF Research Database (Denmark)

    Lodahl, Peter; Bache, Morten; Saffman, Mark

    2001-01-01

    We describe a nonlinear optical system that supports spiral pattern solutions in the field intensity. This new spatial structure is found to bifurcate above a secondary instability in the internally pumped optical parametric oscillator. The analytical predictions of threshold and spatial scale...

  15. Detection of quadrupole relaxation in an optically pumped cesium vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E.; Tornos, J.

    1985-10-01

    The relaxation of quadrupole orientation induced by means of optical pumping in a cesium vapour is experimentally studied, and the results are compared to the theoretical predictions. The optical detection process of this type of orientation is also discussed as a function of the polarization and spectral profile of the detection light.

  16. Hybrid optical pumping of optically dense alkali-metal vapor without quenching gas

    CERN Document Server

    Romalis, M V

    2010-01-01

    Optical pumping of an optically thick atomic vapor typically requires a quenching buffer gas, such as N$_{2}$, to prevent radiation trapping of unpolarized photons which would depolarize the atoms. We show that optical pumping of a trace contamination of Rb present in K metal results in a 4.5 times higher polarization of K than direct optical pumping of K in the absence of N$_{2}$. Such spin-exchange polarization transfer from optically-thin species is useful in a variety of areas, including spin-polarized nuclear scattering targets and electron beams, quantum-non-demolition spin measurements, and ultra-sensitive magnetometry.

  17. Spin-velocity correlations of optically pumped atoms

    Science.gov (United States)

    Marsland, R., III; McGuyer, B. H.; Olsen, B. A.; Happer, W.

    2012-08-01

    We present efficient theoretical tools for describing the optical pumping of atoms by light propagating at arbitrary directions with respect to an external magnetic field, at buffer-gas pressures that are small enough for velocity-selective optical pumping (VSOP) but large enough to cause substantial collisional relaxation of the velocities and the spin. These are the conditions for the sodium atoms at an altitude of about 100 km that are used as guidestars for adaptive optics in modern ground-based telescopes to correct for aberrations due to atmospheric turbulence. We use spin and velocity relaxation modes to describe the distribution of atoms in spin space (including both populations and coherences) and velocity space. Cusp kernels are used to describe velocity-changing collisions. Optical pumping operators are represented as a sum of poles in the complex velocity plane. Signals simulated with these methods are in excellent agreement with previous experiments and with preliminary experiments in our laboratory.

  18. Intensity scaling of an optically pumped potassium laser

    Science.gov (United States)

    Hurd, Edward J.; Holtgrave, Jeremy C.; Perram, Glen P.

    2015-12-01

    A pulsed, optically pumped potassium laser has been demonstrated with output intensity exceeding 7 MW/cm2. By using a surrogate pump, heat pipe gain cell, and helium pressure of 2500 Torr, the intensity of Diode Pumped Alkali Lasers (DPAL) has been increased by a factor of 38. Bottlenecking due to slow fine structure mixing can be avoided without hydrocarbon buffer gases with as many as 375 lasing photons obtained per potassium atom following a 7.4 ns pump pulse. A slope efficiency of 9.4% is achieved and primarily limited by a mismatch between pumped and cavity mode volumes. Laser performance is well described by a three-level, longitudinally averaged model without ionization.

  19. Synchronous Optical Pumping of Quantum Revival Beats for Atomic Magnetometery

    CERN Document Server

    Seltzer, S J; Romalis, M V

    2006-01-01

    We observe quantum beats with periodic revivals due to non-linear spacing of Zeeman levels in the ground state of potassium atoms and demonstrate their synchronous optical pumping by double modulation of the pumping light at the Larmor frequency and the revival frequency. We show that synchronous pumping increases the degree of spin polarization by a factor of 4. As a practical example, we explore the application of this double-modulation technique to atomic magnetometers operating in the geomagnetic field range and find that it can increase the sensitivity and reduce magnetic field orientation-dependent measurement errors endemic to alkali-metal magnetometers.

  20. Modeling of Self-Pumped Singly Resonant Optical Parametric Oscillator

    CERN Document Server

    Deng, Chengxian

    2016-01-01

    A model of the steady-state operating, self-pumped singly resonant optical parametric oscillator (SPSRO) has been developed. The characteristics of quasi three-level laser gain medium pumped longitudinally have been taken into account. The characteristics of standing wave cavity, reabsorption losses, focusing Gaussian beams of the pump laser, fundamental laser and signal wave have been considered in the analyses. Furthermore, The power characteristics of threshold and efficiency have been analyzed, employing a Yb3+-doped periodically poled lithium niobate co-doped with MgO (Yb3+:MgO:PPLN) as the medium of laser gain and second-order nonlinear crystal.

  1. Optical pump wavelength dependence in visible-pump visible-probe spectroscopy of noble metals

    Science.gov (United States)

    Sahota, Derek G.; Lobo, Calvin; Duch, Konrad; Dodge, J. Steven

    2012-10-01

    We have developed a femtosecond visible-pump visible-probe reflectometer with individually tunable pump and probe photon energies. The spectrometer has been used to study optically thick films of the noble metals Au and Cu over a wide variety of pump fluences and photon energies. Through comparison between experimental measurements and two-temperature model (TTM) simulations, we estimate an electron-phonon coupling constant, g, of 2.37 ±0.11 x10^16 Wm-3K-1 for Au and 1.19 ±0.13 x10^17 Wm-3K-1 for Cu, consistent with previous studies. The variation of the optical pump parameters allows a more accurate determination of the electron-phonon coupling constant. The relaxation rate, τ, of the thermally excited electrons is shown to be strongly dependent on the peak electron temperature of the excited sample, and only weakly dependent on the pump photon energy. The static dielectric constant is found to significantly underestimate the dependence of the differential reflectivity on the pump photon energy.

  2. Mirrorless Lasing in Optically Pumped Rubidium Vapor

    Science.gov (United States)

    2013-03-01

    gain of ~ 1 % per cm. The total output power achieved at 7.18 µm was ~ 25 µW. 6 As time progressed, sources to pump the necessary transitions in...The laser was 3.5 mm in diameter and tuned for two photon absorption on the (n) or (n+ 1 ) 2D3 /2,5/2 and (n+2) or (n+3)2S1/2 states in Rb(n=5) and Cs... 1 II. Background

  3. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Science.gov (United States)

    Zhang, Jun-Hai; Zeng, Xian-Jin; Li, Qing-Meng; Huang, Qiang; Sun, Wei-Min

    2013-05-01

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3> → |Fe = 4> resonance pumping can result in the ground state |Fg = 4, mF = 4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4> → |Fe = 3> transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  4. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    Science.gov (United States)

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul

    2011-09-27

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  5. Optically pumped 1550nm wavelength tunable MEMS VCSEL

    DEFF Research Database (Denmark)

    Sahoo, Hitesh Kumar; Ansbæk, Thor; Ottaviano, Luisa

    2016-01-01

    The paper presents the design and fabrication of an optically pumped 1550nm tunable MEMS VCSEL with anenclosed MEMS. The MEMS is defined in SOI and the active material, an InP wafer with quantum wells arebonded to the SOI and the last mirror is made from the deposition of dielectric materials...

  6. Spatiotemporal structures in the internally pumped optical parametric oscillator

    DEFF Research Database (Denmark)

    Lodahl, Peter; Bache, Morten; Saffman, Mark

    2001-01-01

    We analyze pattern formation in doubly resonant second-harmonic generation in the presence of a competing parametric process, also named the internally pumped optical parametric oscillator. Different scenarios are established where either the up- or down-conversion processes dominate the spatiote...... patterns and gray solitons. Estimates of the thresholds for pattern formation under experimentally relevant conditions are given....

  7. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    Science.gov (United States)

    Weiss, Shimon; Schlam, Michael C; Alivisatos, A. Paul

    2014-03-25

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit tight of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  8. Rate equations model and optical external efficiency of optically pumped electrically driven terahertz quantum cascade lasers

    Science.gov (United States)

    Hamadou, A.; Thobel, J.-L.; Lamari, S.

    2016-10-01

    A four level rate equations model for a terahertz optically pumped electrically driven quantum cascade laser is here introduced and used to model the system both analytically and numerically. In the steady state, both in the presence and absence of the terahertz optical field, we solve the resulting nonlinear system of equations and obtain closed form expressions for the levels occupation, population inversion as well as the mid-infrared pump threshold intensity in terms of the device parameters. We also derive, for the first time for this system, an analytical formula for the optical external efficiency and analyze the simultaneous effects of the cavity length and pump intensity on it. At moderate to high pump intensities, we find that the optical external efficiency scales roughly as the reciprocal of the cavity length.

  9. Mathematical model of an optically pumped molecular laser

    CSIR Research Space (South Africa)

    Botha, LR

    2009-07-01

    Full Text Available pumped molecular laser Dr L R Botha, Dr C Bollig, D Esser, C Jacobs, D Preussler SAIP 2009 Durban Page 2 © CSIR 2008 www.csir.co.za Structure of talk • Introduction • Overview of HBr laser • Numerical Model • Comparison... µm laser ring oscillator & pre-amplifier 1.9 µm Optically Pumped Molecular laser @ 4 µm 95:5 HBr Absorption cell Fast detector 2.064 µm ± 1 nm Feedback control box Feedback loop 1 P ie zo m o u nt Fast detector Feedback loop 2 Gas...

  10. Synchronously pumped femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūte, Karolina; Melnikas, Simas; Kičas, Simonas; Trišauskas, Lukas; Vengelis, Julius; Grigonis, Rimantas; Vengris, Mikas; Sirutkaitis, Valdas

    2015-05-01

    We present results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) with broadband complementary chirped mirror pairs (CMP). The SPOPO based on β-BBO nonlinear crystal is pumped by second harmonic of femtosecond Yb:KGW laser and provides signal pulses tunable over spectral range from 625 to 980 nm. More than 500 mW are generated in the signal beam, giving up to 27 % pump power to signal power conversion efficiency. The plane SPOPO cavity mirror pairs were specially designed to provide 99 % reflection in broad spectral range corresponding to signal wavelength tuning (630-1030 nm) and to suppress group delay dispersion (GDD) oscillations down to +/-10 fs2. Dispersion properties of designed mirrors were tested with white light interferometer (WLI) and attributed to the SPOPO tuning behaviour.

  11. Wavelength diversity in optically pumped alkali vapor lasers

    Science.gov (United States)

    Perram, Glen P.

    2017-01-01

    Alternative wavelengths for optically pumped alkali vapor lasers have been developed using single photon excitation of higher lying P-states, stimulated Raman processes, two-photon excitation of S and D states, and electric quadruple excitation on S-D transitions. Two photon excitation of Cs 72D leads to competing and cascade lasing producing red and infrared lasers operating on the D-P transitions, followed by ultraviolet, blue, the standard near infrared DPAL transitions operating on P-S transitions. The S-D pump transitions are fully bleached at pump intensities exceeding 1 MW/cm2, allowing for lasing transitions that terminate on the ground state. The kinetics of these systems are complex due to competition for population inversion among the many optical transitions. An optically pumped mid-infrared rubidium pulsed, mirrorless laser has also been demonstrated in a heat pipe along both the 62P3/2 - 62S1/2 transition at 2.73 μm and the 62P1/2 - 62S1/2 transition at 2.79 μm with a maximum energy of 100 nJ. Performance improves dramatically as the rubidium vapor density is increased, in direct contradiction with the prior work. No scaling limitations associated with energy pooling or ionization kinetics have been observed. Practical application for infrared counter measures depends on the further development of blue diode pump sources. Finally, stimulated electronic Raman scattering and hyper-Raman processes in potassium vapor near the D1 and D2 lines have been observed using a stable resonator and pulsed laser excitation. First and second order Stokes and anti-Stokes lines were observed simultaneously and independently for a pump laser tuning range exceeding 70 cm-1. When the pump is tuned between the K D1 and D2 lines, an efficient hyper-Raman process dominates with a slope efficiency that exceeds 10%. Raman shifted laser may be useful as a target illuminator or atmospheric compensation beacon for a high power diode pumped alkali laser.

  12. Actively Pumped Optical Filters at 532 nm

    Science.gov (United States)

    Billmers, Richard I.; Gayen, S. K.; Contarino, Vincent M.; Scharpf, William J.; Squicciarini, Martin F.; Allocca, David A.

    1995-01-01

    The operation of two narrow-band optical filters at 532.33 nm is presented. Both of these filters operate on the 4P(sub 1/2) to 8S(sub 1/2) excited-state transition in potassium vapor. One of the filters is based on excited-state Faraday effect, and requires the application of an external axial magnetic field. The peak transmission of this filter is approximately 3.5% with a linewidth of less than 10 GHz. The second filter does not require a magnetic field for its operation, but readily attains peak transmissions of 25-30%. The 4P(sub 1/2) state is excited by a 769.9 nm light pulse which is linearly polarized for the first scheme and circularly polarized for the second.

  13. A microfabricated optically-pumped magnetic gradiometer

    Science.gov (United States)

    Sheng, D.; Perry, A. R.; Krzyzewski, S. P.; Geller, S.; Kitching, J.; Knappe, S.

    2017-01-01

    We report on the development of a microfabricated atomic magnetic gradiometer based on optical spectroscopy of alkali atoms in the vapor phase. The gradiometer, which operates in the spin-exchange relaxation free regime, has a length of 60 mm and cross sectional diameter of 12 mm, and consists of two chip-scale atomic magnetometers which are interrogated by a common laser light. The sensor can measure differences in magnetic fields, over a 20 mm baseline, of 10 fT/ Hz1 /2 at frequencies above 20 Hz. The maximum rejection of magnetic field noise is 1000 at 10 Hz. By use of a set of compensation coils wrapped around the sensor, we also measure the sensor sensitivity at several external bias field strengths up to 150 mG. This device is useful for applications that require both sensitive gradient field information and high common-mode noise cancellation.

  14. Proliferation-resistant stable isotope separation based on optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol-Jung; Park, Hyunmin; Ko, Kwang-Hoon; Lim, Gwon; Kim, Taek-Soo; Rho, Sipyo; Cha, Yong-Ho; Han, Jamin; Jeong, Do-Young [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of). Quantum Optics Division

    2008-07-01

    Korea Atomic Energy Research Institute (KAERI) has developed the laser stable isotope separation based on optical pumping which can be applied to isotopes with small isotopic shift, provides high enrichment, is economical owing to high efficiency, and is proliferation-resistant. KAERI's laser isotope separation is based on isotope-selective optical pumping by very narrow bandwidth continuous wave laser followed by efficient infrared photo-ionization. KAERI demonstrated the pilot production of Tl-203 enriching over 97 % and separating 100 mg/hr. KAERI also demonstrated the separation of Yb-168 over 30 % and Yb- 176 over 97 % with tens of mg/hr. KAERI plans to scale up the production of Tl-203 up to 500 mg/hr and apply it to separation of Zn-67, Zn-70, Ba-130 and Ca-48 which are very important in medical industry and basic sciences. (author)

  15. 1,3-Substituted Imidazolidine-2,4,5-triones: Synthesis and Inhibition of Cholinergic Enzymes

    Directory of Open Access Journals (Sweden)

    Josef Jampilek

    2011-09-01

    Full Text Available A series of novel and highly active acetylcholinesterase and butyrylcholinesterase inhibitors derived from substituted benzothiazoles containing an imidazolidine-2,4,5-trione moiety were synthesized and characterized. The molecular structure of 1-(2,6-diisopropyl-phenyl-3-[(1R-1-(6-fluoro-1,3-benzothiazol-2-ylethyl]-imidazolidine-2,4,5-trione (3g was determined by single-crystal X-ray diffraction. Both optical isomers are present as two independent molecules in the triclinic crystal system. The lipophilicity of the compounds was determined as the partition coefficient log Kow using the traditional shake-flask method. The in vitro inhibitory activity on acetylcholinesterase from electric eel and butyrylcholinesterase isolated from equine serum was determined. The inhibitory activity on acetylcholinesterase was significantly higher than that of the standard drug rivastigmine. The discussed compounds are also promising inhibitors of butyrylcholinesterase, as some of the prepared compounds inhibit butyrylcholinesterase better than the internal standards rivastigmine and galanthamine. The highest inhibitory activity (IC50 = 1.66 μmol/L corresponds to the compound 1-(4-isopropylphenyl-3-[(R-1-(6-fluorobenzo[d]thiazol-2-ylethyl]imidazolidine-2,4,5-trione (3d. For all the studied compounds, the relationships between the lipophilicity and the chemical structure as well as their structure-activity relationships are discussed.

  16. Scaling of an Optically Pumped Mid-Infrared Rubidium Laser

    Science.gov (United States)

    2015-03-26

    model for alkali metal vapor lasers : part I. Narrowband optical pumping.” Applied Physics B 101, No. 1-2, 45-56 (2010). W. Klennert, “Development...an overview,” High-Power Laser Ablation 2008. International Society for Optics and Photonics, 700521 (2008). 64 W.F. Krupke and others, “New...Physics B 89, No. 4, 595-601 (2007). P.P. Sorokin and J.R. Lankard, “Infrared Lasers Resulting from Giant Pulse Laser Excitation of Alkali Metal

  17. Four-channel optically pumped atomic magnetometer for magnetoencephalography.

    Science.gov (United States)

    Colombo, Anthony P; Carter, Tony R; Borna, Amir; Jau, Yuan-Yu; Johnson, Cort N; Dagel, Amber L; Schwindt, Peter D D

    2016-07-11

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are 1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization.

  18. Simultaneous Hosting of Positive and Negative Trions and the Enhanced Direct Band Emission in MoSe2/MoS2 Heterostacked Multilayers.

    Science.gov (United States)

    Kim, Min Su; Seo, Changwon; Kim, Hyun; Lee, Jubok; Luong, Dinh Hoa; Park, Ji-Hoon; Han, Gang Hee; Kim, Jeongyong

    2016-06-28

    Heterostacking of layered transition-metal dichalcogenide (LTMD) monolayers (1Ls) offers a convenient way of designing two-dimensional exciton systems. Here we demonstrate the simultaneous hosting of positive trions and negative trions in heterobilayers made by vertically stacking 1L MoSe2 and 1L MoS2. The charge transfer occurring between the 1Ls of MoSe2 and MoS2 converted the polarity of trions in 1L MoSe2 from negative to positive, resulting in the presence of positive trions in the 1L MoSe2 and negative trions in the 1L MoS2 of the same heterostacked bilayer. Significantly enhanced MoSe2 photoluminescence (PL) in the heterostacked bilayers compared to the PL of 1L MoSe2 alone suggests that, unlike other previously reported heterostacked bilayers, direct band transition of 1L MoSe2 in heterobilayer was enhanced after the vertical heterostacking. Moreover, by inserting hexagonal BN monolayers between 1L MoSe2 and 1L MoS2, we were able to adjust the charge transfer to maximize the MoSe2 PL of the heteromultilayers and have achieved a 9-fold increase of the PL emission. The enhanced optical properties of our heterostacked LTMDs suggest the exciting possibility of designing LTMD structures that exploit the superior optical properties of 1L LTMDs.

  19. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun-Hai; Zeng Xian-Jin; Li Qing-Meng; Huang Qiang; Sun Wei-Min

    2013-01-01

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations.The process,described by a three-level model with the A scheme,shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms.The |Fg =3> → |Fe-4> resonance pumping can result in the ground state |Fg =4,mF =4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg =4.To enhance the anisotropy in the ground state,we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg =4> → |Fe =3>transition,in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  20. 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.

  1. Experimental Investigation of Pump-to-Signal Noise Transfer in One-Pump Phase Insensitive Fibre Optic Parametric Amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lund-Hansen, Toke; Peucheret, Christophe

    2011-01-01

    This paper presents a detailed experimental characterization of the relative intensity noise (RIN) transferred from the pump to the signal in one-pump phase insensitive fibre optic parametric amplifiers. We extend an existing experimental and theoretical work towards higher frequencies, showing...

  2. Charge-controlled nuclear polarization of a single InAs/GaAs quantum dot under optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Eble, Benoit; Krebs, Olivier; Lemaitre, Aristide; Kowalik, Katarzyna; Kudelski, Arkadiusz; Voisin, Paul [CNRS-Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France); Urbaszek, Bernhard; Amand, Thierry; Marie, Xavier [Laboratoire de Nanophysique Magnetisme et Optoelectronique, INSA, 31077 Toulouse Cedex 4 (France)

    2006-07-01

    We report on electron spin physics in a single charge-tunable self-assembled InAs/GaAs quantum dot. The hyperfine interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser-shift depends on the trion state X{sup +} or X{sup -}, and remarkably its amplitude does not vanish in zero magnetic field. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Polarization-insensitive fiber optical parametric amplifier based on polarization diversity technique with dual parallel pumps

    Institute of Scientific and Technical Information of China (English)

    YIN Lu; SANG Xin-zhu; ZHANG Qi; XIN Xiang-jun; YU Chong-xiu; Da-xiong

    2011-01-01

    By analyzing the principle of dual-pump parametric amplification and the polarization dependent gain of fiber optical parametric amplifier (FOPA), a polarization-insensitive FOPA based on polarization-diversity technique with dual parallel pumps is presented. The performances of polarization-insensitivity, gain and BER are theoretically analyzed and numerically simulated by comparing the proposed scheme with parallel pump solution and orthogonal pump solution. The presented solution can reduce the complexity of state of polarization (SoP) of pumps.

  4. A Novel All-optical Wavelength Converter Based on Self-pump Four-wave Mixing

    Institute of Scientific and Technical Information of China (English)

    CHEN Jianxiao; CHEN Zhangyuan; TAO Zhenning; WU Deming; XU Anshi; WANG Ziyu

    2002-01-01

    A novel scheme of all-optical wavelength converter(AOWC) based on dual pump four-wave mixing(DP-FWM) was demonstrated. To suppress the ASE noise of the semiconductor optical amplifier (SOA), one of the two pumps was generated interiorly from a loop laser constructed mainly by tunable optical filter and SOA. The theoretical model and some experimental results were presented.

  5. Simplified approach for quantitative calculations of optical pumping

    Science.gov (United States)

    Atoneche, Fred; Kastberg, Anders

    2017-07-01

    We present a simple and pedagogical method for quickly calculating optical pumping processes based on linearised population rate equations. The method can easily be implemented on mathematical software run on modest personal computers, and can be generalised to any number of concrete situations. We also show that the method is still simple with realistic experimental complications taken into account, such as high level degeneracy, impure light polarisation, and an added external magnetic field. The method and the associated mathematical toolbox should be of value in advanced physics teaching, and can also facilitate the preparation of research tasks.

  6. High Performance Small Optically Pumped Caesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Wei; YANG Dong-Hai

    2007-01-01

    An experiment of a high performance small optically pumped caesium (Cs) beam frequency standard is reported. An extended cavity diode laser works as the probing laser, of which the frequency is stabilized by the Zeeman modulation method. The running parameters of the frequency standard are dynamically optimized via digital servo electronics. The experimental setup improves the frequency stability up to 1.8 × 10-12 atτ= 1 s and about 1.0 × 10~13 at τ= 105 s (Allan deviation).

  7. DBR-free optically pumped semiconductor disk lasers

    Science.gov (United States)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2015-03-01

    Optically pumped semiconductor disk lasers (SDLs) provide high beam quality with high average-power power at designer wavelengths. However, material choices are limited by the need for a distributed Bragg reflector (DBR), usually monolithically integrated with the active region. We demonstrate DBR-free SDL active regions, which have been lifted off and bonded to various transparent substrates. For an InGaAs multi-quantum well sample bonded to a diamond window heat spreader, we achieved CW lasing with an output power of 2 W at 1150 nm with good beam quality.

  8. Optical pumping of rubidium atoms in a parahydrogen matrix

    Science.gov (United States)

    Weinstein, Jonathan; Arnott, W. Patrick; Christy, Tim; Hartzell, Chase; Kanagin, Andrew; Momose, Takamasa; Patterson, David; Upadhyay, Sunil

    2016-05-01

    Building on prior work with rubidium atoms in a cryogenic argon matrix, we have grown solid parahydrogen crystals doped with rubidium atoms. Typical rubidium densities are on the order of 1017 cm-3. We have demonstrated optical pumping of the atomic spin of the implanted rubidium atoms; the measured spin polarization signals are roughly one order of magnitude larger than what was achieved in argon matrices. The combination of high atomic densities and optical addressability make this a promising experimental platform for applications such as magnetometry and fundamental physics measurements. Spin lifetimes (T1) on the order of 1 second have been observed. Progress towards measuring coherence times (T2) will be discussed. This material is based on work supported by the National Science Foundation under Grant No. PHY 1265905.

  9. Investigation of Hg/sub 2/ as a discharge pumped optical storage medium

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlich, D J; Osgood, Jr, R M

    1978-12-01

    The report describes work performed in the period 1 October 1977 to 30 September 1978 on the extraction of energy from metastable Hg/sub 2/ by optical techniques. The major accomplishments have included: (1) assessment of optical extraction techniques for laser fusion applications; (2) demonstration of 20X enhancements in the population of the UV-radiating level by optical pumping with mid-IR lasers; (3) analysis of the IR optical pumping process through the induced emission spectrum; (4) parametric studies of the excitation wavelength, temperature and pressure dependences of extraction by optical pumping; (5) studies of the saturation of mid-IR optical pumping; (6) modeling of large-scale extraction for laser fusion applications; (7) studies of optical pumping of Hg/sub 2/ by high power ArF laser (193 nm) radiation; and (8) studies of Hg/sub 2/ excimer structure and collisional destruction rates.

  10. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    Science.gov (United States)

    Isaienko, Oleksandr; Robel, István

    2016-03-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7-20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  11. Thin film detection of High Energy Materials: Optical Pumping Approach

    CERN Document Server

    Barthwal, Sachin

    2014-01-01

    We present our work on High Energy Material detection based on thin film of Lithium using the phenomenon of Optical Pumping. The Li atoms present in the thin film are optically pumped to one of the ground hyperfine energy levels so that they can no more absorb light from the resonant light source. Now in presence of a RF signal, which quantifies the ambient magnetic field, this polarized atomic system is again randomized thus making it reabsorb the resonant light. This gives a quantified measurement of the magnetic field surrounding the thin film detector. This is then mapped to the presence of magnetic HEM and hence the HEM are detected. Our approach in this regard starts with verifying the stability of Lithium atoms in various solvents so as to get a suitable liquid medium to form a thin film. In this regard, various UV-visible characterization spectra are presented to finally approach a stable system for the detection. We have worked on around 10 polar and non- polar solvents to see the stability criteria....

  12. Low pumping energy mode of the "optical bars''/"optical lever" topologies of gravitational-wave antennae

    OpenAIRE

    Khalili, F. Ya

    2003-01-01

    The ``optical bars''/``optical lever'' topologies of gravitational-wave antennae allow to obtain sensitivity better that the Standard Quantum Limit while keeping the optical pumping energy in the antenna relatively low. Element of the crucial importance in these schemes is the local meter which monitors the local test mirror position. Using cross-correlation of this meter back-action noise and its measurement noise it is possible to further decrease the optical pumping energy. In this case th...

  13. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors

    NARCIS (Netherlands)

    Euser, T.G.; Harding, P.J.; Vos, Willem L.

    2009-01-01

    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21 050 cm−1. A broad pump scan range allows a large optical

  14. Assignment of the /Li-7/2 optically pumped laser transitions pumped by Ar/+/ and Kr/+/ laser lines

    Science.gov (United States)

    Verma, K. K.; Stwalley, W. C.; Zemke, W. T.

    1981-01-01

    Welling and Wellegehausen (1977) have reported a list of Na2 and Li2 lines (belonging to B-X and A-X systems) which lase when vapors of these dimers are pumped with an Ar(+) or Kr(+) laser. A description is presented of a fluorescence study of the A-X system of the (Li-7)2 molecule excited by a Kr(+) laser (6471 A). The optically pumped laser lines are identified as P and R doublets in two different fluorescence series. The conditions which favor lasing action of these lines are pointed out. All but one of the known optically pumped laser lines of (Li-7)2 along with their assignments are presented in a table. For each pumping line, several additional wavelengths are listed which satisfy the condition for laser oscillations and which might well lase well under slightly improved conditions.

  15. Optically pumped mid-infrared light emitter on silicon

    Science.gov (United States)

    Elizondo, L. A.; Li, Y.; Sow, A.; Kamana, R.; Wu, H. Z.; Mukherjee, S.; Zhao, F.; Shi, Z.; McCann, P. J.

    2007-05-01

    Characterization of a IV-VI semiconductor structure consisting of a PbSe/PbSrSe multiple quantum well (MQW) active region between distributed Bragg reflectors grown by molecular beam epitaxy on a Si(111) substrate is described. Pulsed photoluminescence (PL) spectra exhibited interband electronic transition energies ranging linearly with temperature from 231.4 meV at 150 K to 299.4 meV at 300 K, while continuous wave (cw) PL spectra exhibited only the vertical optical cavity mode with emission varying between 299.2 meV at 150 K to 301.1 meV at 300 K. A maximum PL emission power of approximately 1.8 mW was obtained for cw diode laser pumping when the heat sink temperature was 200 K. Data are consistent with a localized epilayer heating effect of about 100 deg where the interband electronic transition energy is coincident with the vertical optical cavity mode. In spite of significant sample heating and associated thermal expansion mismatch stress, cw PL emission intensity was stable with no noticeable degradation in intensity after repeated measurements. These results show that IV-VI epitaxial layers on silicon are viable materials for fabricating reliable light emitters for on-chip optical interconnects.

  16. Photoluminescence and optical transmission of diffusion-pump oils.

    Science.gov (United States)

    Kroes, R. L.

    1973-01-01

    The photoluminescence and optical transmission of the four widely used diffusion-pump oils, DC-705, DC-704, Convalex-10, and Convoil-20, were measured. Each of the oils was found to be transparent throughout the visible region, showed some absorption in the near-UV region, and became very opaque below approximately 300 nm. Both Convalex-10 and Convoil-20 turned yellow after exposure to UV light. No such change was noted in DC-705 or DC-704. Photoluminescence was produced in each of the four oils when irradiated with UV light. Both DC-705 and DC-704 had a nearly identical luminescence spectra that peaked at 350 nm. The spectra of Convalex-10 and Convoil-20 were fairly complex, with several peaks in the visible region.

  17. Hyperfine relaxation of an optically pumped cesium vapor

    Energy Technology Data Exchange (ETDEWEB)

    Tornos, J.; Amare, J.C.

    1986-07-01

    The relaxation of hyperfine orientation indirectly induced by optical pumping with a sigma-polarized D/sub 1/-light in a cesium vapor in the presence of Ar is experimentally studied. The detection technique ensures the absence of quadrupole relaxation contributions in the relaxation signals. The results from the dependences of the hyperfine relaxation rate on the temperature and argon pressure are: diffusion coefficient of Cs in Ar, D/sub 0/ = 0.101 +- 0.010 cm/sup 2/s/sup -1/ at 0/sup 0/C and 760 Torr; relaxation cross section by Cs-Ar collisions, sigma/sub c/ = (104 +- 5) x 10/sup -23/ cm/sup 2/; relaxation cross section by Cs-Cs (spin exchange) collisions, sigma/sub e//sub x/ = (1.63 +- 0.13) x 10/sup -14/ cm/sup 2/.

  18. Solid state carbon nanotube device for controllable trion electroluminescence emission

    Science.gov (United States)

    Liang, Shuang; Ma, Ze; Wei, Nan; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2016-03-01

    Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ~5 × 10-4 photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for gradually increasing bias were also investigated. The realization of electrically induced pure trion emission opens up a new opportunity for CNT film-based optoelectronic devices, providing a new degree of freedom in controlling the devices to extend potential applications in spin or magnetic optoelectronics fields.Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ~5 × 10-4 photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for

  19. Correlation and dimensional effects of trions in carbon nanotubes

    DEFF Research Database (Denmark)

    Rønnow, Troels Frimodt; Pedersen, Thomas Garm; Cornean, Horia

    2010-01-01

    We study the binding energies of singlet trions, i.e., charged excitons, in carbon nanotubes. The problem is modeled, through the effective-mass model, as a three-particle complex on the surface of a cylinder, which we investigate using both one- and two-dimensional expansions of the wave function...... are used to compute physical binding energies for a wide selection of carbon nanotubes. In addition, the dependence on dielectric screening is examined. Our findings indicate that trions are detectable at room temperature in carbon nanotubes with radius below 8 Å....

  20. Saturation Effect on Pump-to-Signal Intensity Modulation Transfer in Single-Pump Phase-Insensitive Fibre Optic Parametric Amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

    2011-01-01

    A numerical and experimental characterization of how signal gain saturation affects the transfer of the intensity modulation of the pump to the signal in single-pump phaseinsensitive fibre optic parametric amplifiers is presented.......A numerical and experimental characterization of how signal gain saturation affects the transfer of the intensity modulation of the pump to the signal in single-pump phaseinsensitive fibre optic parametric amplifiers is presented....

  1. Dynamic characterization of silicon nanowires using a terahertz optical asymmetric demultiplexer-based pump-probe scheme

    DEFF Research Database (Denmark)

    Ji, Hua; Cleary, C. S.; Dailey, J. M.;

    2012-01-01

    Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers....

  2. Optical Pumping Experiments on Next Generation Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S J; Fournier, K B; Scott, H; Chung, H K; Lee, R W

    2004-07-29

    Laser-based plasma spectroscopic techniques have been used with great success to determine the line shapes of atomic transitions in plasmas, study the population kinetics of atomic systems embedded in plasmas, and look at the redistribution of radiation. However, the possibilities for optical lasers end for plasmas with n{sub e}>10{sup 22}cm{sup -3} as light propagation is severely altered by the plasma. The construction of the Tesla Test Facility(TTF) at DESY(Deutsche Elektronen-Synchrotron), a short pulse tunable free electron laser in the vacuum-ultraviolet and soft X-ray regime (VUV FEL), based on the SASE(self amplified spontaneous emission) process, will provide a major advance in the capability for dense plasma-related research. This source will provide 10{sup 13} photons in a 200 fs duration pulse that is tunable from {approx} 6nm to 100nm. Since an VUV FEL will not have the limitation associated with optical lasers the entire field of high density plasmas kinetics in laser produced plasma will then be available to study with tunable source. Thus, one will be able to use this and other FEL x-ray sources to pump individual transitions creating enhanced population in the excited states that can easily be monitored. We show two case studies illuminating different aspects of plasma spectroscopy.

  3. Design and analysis of optically pumped semiconductor VECSEL with ANECz optical control layer

    Institute of Scientific and Technical Information of China (English)

    Yuqi Zhou; Dapeng Zhao; Yajuan Li; Qingxin Yang

    2008-01-01

    Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo materials have photo-induced birefringence which is related to optical power and polarization angle of the light. Based on the photo-induced birefringence of azo materials, we design a new type of optically pumped semiconductor vertical external cavity surface emitting laser (OPS-VECSEL) which can control the polarization and frequency of the ejection laser. The functional molecules of azo materials are [3-azo- (4'nitro)]-(9-ethyl)-carbazole (ANECz).

  4. A New Pumping-Probing Scheme for the Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    陈景标; 朱程锦; 王凤芝; 杨东海

    2001-01-01

    A new pumping-probing scheme for the optically pumped cesium beam frequency standard has been experimentally tested in our laboratory. The stability of the optically pumped cesium beam frequency standard was measured by comparing its 10 MHz output with an HP5071A commercial cesium atomic clock. The result shows that the frequency stability for the 1 s and 30000s sample times are 1.2 × 10-11 and 3.7 × 10-13, respectively. It was proved that the new pumping scheme works well.

  5. Phosphate-core silica-clad Er/Yb-doped optical fiber and cladding pumped laser.

    Science.gov (United States)

    Egorova, O N; Semjonov, S L; Velmiskin, V V; Yatsenko, Yu P; Sverchkov, S E; Galagan, B I; Denker, B I; Dianov, E M

    2014-04-07

    We present a composite optical fiber with a Er/Yb co-doped phosphate-glass core in a silica glass cladding as well as cladding pumped laser. The fabrication process, optical properties, and lasing parameters are described. The slope efficiency under 980 nm cladding pumping reached 39% with respect to the absorbed pump power and 28% with respect to the coupled pump power. Due to high doping level of the phosphate core optimal length was several times shorter than that of silica core fibers.

  6. Solid state carbon nanotube device for controllable trion electroluminescence emission.

    Science.gov (United States)

    Liang, Shuang; Ma, Ze; Wei, Nan; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2016-03-28

    Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ∼5 × 10(-4) photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for gradually increasing bias were also investigated. The realization of electrically induced pure trion emission opens up a new opportunity for CNT film-based optoelectronic devices, providing a new degree of freedom in controlling the devices to extend potential applications in spin or magnetic optoelectronics fields.

  7. Fiber-optic parametric amplifier and oscillator based on intracavity parametric pump technique.

    Science.gov (United States)

    Luo, Zhengqian; Zhong, Wen-De; Tang, Ming; Cai, Zhiping; Ye, Chenchun; Xiao, Xiaosheng

    2009-01-15

    A cost-effective fiber optical parametric amplifier (FOPA) based on the laser intracavity pump technique has been proposed and demonstrated experimentally. The parametric process is realized by inserting a 1 km highly nonlinear dispersion-shifted fiber (HNL-DSF) into a fiber ring-laser cavity that consists of a high-power erbium-doped fiber (EDF) amplifier and two highly reflective fiber Bragg gratings. Compared with the conventional parametric pump schemes, the proposed pumping technique is free from a tunable semiconductor laser as the pump source and also the pump phase modulation. When the oscillating power of 530 mW in the EDF laser cavity is achieved to pump the HNL-DSF, a peak parametric gain of 27.5 dB and a net gain over 45 nm are obtained. Moreover, a widely tunable fiber-optic parametric oscillator is further developed using the FOPA as a gain medium.

  8. Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene

    CERN Document Server

    Weis, Peter; Rahm, Marco

    2013-01-01

    It is evidenced by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. In a first step, the complex conductivity of graphene under optical pumping is calculated and the proper conditions for terahertz amplification in single layer graphene are determined. It is shown that amplification in graphene occurs for temperatures up to room temperature and for moderate pump intensities when pumped at a telecommunication wavelength $\\lambda=1.5~\\mathrm{\\mu m}$. Furthermore, the amplification properties of graphene are evaluated and discussed at a temperature as low as $T=77~\\mathrm{K}$ and a pump intensity $I=300~\\mathrm{mW/mm^2}$ to investigate the coupling between graphene and a plasmonic split ring resonator (SRR) metamaterial. The contributions of ohmic and dielectric loss mechanisms are studied by full wave simulations. As a result, it is found that the loss of a split-ring resonator metamaterial can be compensated by optically stimulat...

  9. Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing

    Science.gov (United States)

    Wang, Weiqiang; Chu, Sai T.; Little, Brent E.; Pasquazi, Alessia; Wang, Yishan; Wang, Leiran; Zhang, Wenfu; Wang, Lei; Hu, Xiaohong; Wang, Guoxi; Hu, Hui; Su, Yulong; Li, Feitao; Liu, Yuanshan; Zhao, Wei

    2016-01-01

    In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness. PMID:27338250

  10. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    Science.gov (United States)

    Kim, Young Jin; Savukov, Igor

    2016-04-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  11. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer.

    Science.gov (United States)

    Kim, Young Jin; Savukov, Igor

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  12. Revealing hidden optical transitions with tuneable optical-pump THz-probe spectroscopy

    CERN Document Server

    Novelli, Fabio

    2016-01-01

    While a vast amount of theoretical and experimental approaches can be used to study the band structure of simple solids, the investigation of the electronic properties of high-temperature superconductors and other strongly correlated systems is far less simple. Limitations to both theory and experiments arise from e.g. the many-body nature of the mathematical problem and from the non-trivial surface reconstructions, respectively. Here we propose a novel approach able to reveal energy gaps between band extrema that cannot be identified from the equilibrium optical properties. By combining finely-tunable visible pump pulses with terahertz probe fields, we identify changes to the transient conductivity as the pump wavelength is changed and the density of carriers in different parts of the band structure varies. This approach is demonstrated on a typical semiconductor, undoped silicon, where we identify the band minimum at the $L$ point of the conduction band, corresponding to the second lowest energy indirect ga...

  13. Optically pumped tunable HBr laser in the mid-infrared region

    CSIR Research Space (South Africa)

    Koen, W

    2014-06-01

    Full Text Available An optically pumped tunable HBr laser has been demonstrated for the first time. The pump source was a single-frequency Ho:YLF laser and amplifier system, which was locked to the 2064 nm absorption line of HBr. Laser oscillation was demonstrated...

  14. Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser

    NARCIS (Netherlands)

    Klein, M.E.; Adel, P.; Auerbach, M.; Fallnich, C.; Gross, P.; Boller, Klaus J.

    2003-01-01

    We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-ms-long pulses from an actively Q-switched Y

  15. Improvement of a polarized alkali ion source by means of optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Koch, E.; Jaensch, H.; Kamke, W.; Broermann, W.; Fick, D.

    1982-01-01

    A source for polarized alkali ions can be improved considerably by optical pumping of the atom beam in combination with a modified weak field transition. M-level populations were investigated using laser induced fluorescence in a magnetic field.

  16. Wave optics simulation of diode pumped alkali laser (DPAL)

    Science.gov (United States)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio

    2016-03-01

    A numerical simulation code for a diode pumped alkali laser (DPAL) was developed. The code employs the Fresnel- Kirchhoff diffraction integral for both laser mode and pump light propagations. A three-dimensional rate equation set was developed to determine the local gain. The spectral divergence of the pump beam was represented by a series of monochromatic beams with different wavelengths. The calculated results showed an excellent agreements with relevant experimental results. It was found that the main channel of the pump power drain is the spontaneous emission from the upper level of the lasing transition.

  17. Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene

    Science.gov (United States)

    Weis, P.; Garcia-Pomar, J. L.; Rahm, M.

    2014-04-01

    It is evidenced by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. In a first step, the complex conductivity of graphene under optical pumping is calculated and the proper conditions for terahertz amplification in single layer graphene are determined. It is shown that amplification in graphene occurs for temperatures up to room temperature and for moderate pump intensities when pumped at a telecommunication wavelength $\\lambda=1.5~\\mathrm{\\mu m}$. Furthermore, the amplification properties of graphene are evaluated and discussed at a temperature as low as $T=77~\\mathrm{K}$ and a pump intensity $I=300~\\mathrm{mW/mm^2}$ to investigate the coupling between graphene and a plasmonic split ring resonator (SRR) metamaterial. The contributions of ohmic and dielectric loss mechanisms are studied by full wave simulations. As a result, it is found that the loss of a split-ring resonator metamaterial can be compensated by optically stimulated amplification in graphene. Moreover, it is shown that a hybrid material consisting of asymmetric split-ring resonators and optically pumped graphene can exceed the laser threshold condition and can emit coherent THz radiation at minimum output power levels of $6 0~\\mathrm{nW/mm^2}$. The use of optically pumped graphene is well suited for loss compensation in THz metamaterials and paves the way to new kinds of coherent THz sources.

  18. Optically pumped terahertz lasers with high pulse repetition frequency: theory and design

    Institute of Scientific and Technical Information of China (English)

    Yude Sun; Shiyou Fu; Jing Wang; Zhenghe Sun; Yanchao Zhang; Zhaoshuo Tian; Qi Wang

    2009-01-01

    Optically pumped terahertz (THz) lasers with high pulse repetition frequency are designed. Such a laser includes two parts: the optically pumping laser and the THz laser. The structures of the laser are described and analyzed. The rate equations for the pulsed THz laser are given. The kinetic process and laser pulse waveform for this kind of laser are numerically calculated based on the theory of rate equations. The theoretical results give a helpful guide to the research of such lasers.

  19. Production of a nuclear spin polarized /sup 23/Na-beam by optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Kamke, W.; Broermann, W.; Fick, D.

    1981-11-01

    Nuclear spin polarization of an atomic /sup 23/Na-beam was produced by a combination of optical pumping with a dye laser and a sextupole magnet and alternatively, by optical pumping with two dye lasers. The maximum value measured for the vector polarization was P/sub 2/ = 0.86 +- 0.08, using beam foil spectroscopy. Further improvements of polarized ion sources based on this principle are discussed.

  20. Optical silencing of C. elegans cells with arch proton pump.

    Directory of Open Access Journals (Sweden)

    Ayako Okazaki

    Full Text Available BACKGROUND: Optogenetic techniques using light-driven ion channels or ion pumps for controlling excitable cells have greatly facilitated the investigation of nervous systems in vivo. A model organism, C. elegans, with its small transparent body and well-characterized neural circuits, is especially suitable for optogenetic analyses. METHODOLOGY/PRINCIPAL FINDINGS: We describe the application of archaerhodopsin-3 (Arch, a recently reported optical neuronal silencer, to C. elegans. Arch::GFP expressed either in all neurons or body wall muscles of the entire body by means of transgenes were localized, at least partially, to the cell membrane without adverse effects, and caused locomotory paralysis of worms when illuminated by green light (550 nm. Pan-neuronal expression of Arch endowed worms with quick and sustained responsiveness to such light. Worms reliably responded to repeated periods of illumination and non-illumination, and remained paralyzed under continuous illumination for 30 seconds. Worms expressing Arch in different subsets of motor neurons exhibited distinct defects in the locomotory behavior under green light: selective silencing of A-type motor neurons affected backward movement while silencing of B-type motor neurons affected forward movement more severely. Our experiments using a heat-shock-mediated induction system also indicate that Arch becomes fully functional only 12 hours after induction and remains functional for more than 24 hour. CONCLUSIONS/SGNIFICANCE: Arch can be used for silencing neurons and muscles, and may be a useful alternative to currently widely used halorhodopsin (NpHR in optogenetic studies of C. elegans.

  1. Polarised two-photon excitation of quantum well excitons for manipulation of optically pumped terahertz lasers

    Energy Technology Data Exchange (ETDEWEB)

    Slavcheva, G., E-mail: gsk23@bath.ac.uk [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Kavokin, A.V., E-mail: A.Kavokin@soton.ac.uk [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Spin Optics Laboratory, St. Petersburg State University, 1, Ulyanovskaya 198504 (Russian Federation)

    2014-11-15

    Optical pumping of excited exciton states in a semiconductor quantum well embedded in a microcavity is a tool for realisation of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited (2p) and ground (1s) exciton state. We show that the probability of two-photon absorption by a 2p-exciton is strongly dependent on the polarisation of both pumping photons. Five-fold variation of the threshold power for terahertz lasing by switching from circular to co-linear pumping is predicted. We identify photon polarisation configurations for achieving maximum THz photon generation quantum efficiency.

  2. Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot.

    Science.gov (United States)

    Chekhovich, E A; Makhonin, M N; Kavokin, K V; Krysa, A B; Skolnick, M S; Tartakovskii, A I

    2010-02-12

    We demonstrate that efficient optical pumping of nuclear spins in semiconductor quantum dots (QDs) can be achieved by resonant pumping of optically forbidden transitions. This process corresponds to one-to-one conversion of a photon absorbed by the dot into a polarized nuclear spin, and also has potential for initialization of hole spin in QDs. We find that by employing this spin-forbidden process, nuclear polarization of 65% can be achieved, markedly higher than from pumping the allowed transition, which saturates due to the low probability of electron-nuclear spin flip-flop.

  3. A Subfemtotesla Atomic Magnetometer Based on Hybrid Optical Pumping of Potassium and Rubidium

    Science.gov (United States)

    Li, Yang; Cai, Hongwei; Ding, Ming; Quan, Wei; Fang, Jiancheng

    2016-05-01

    Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have been researched and applied extensively. Higher sensitivity and spatial resolution combined with no cryogenic cooling of atomic magnetometers would enable many applications with low cost, including the magnetoencephalography (MEG). Ultrahigh sensitivity atomic magnetometer is considered to be the main development direction for the future. Hybrid optical pumping has been proposed to improve the efficiency of nuclear polarization. But it can also be used for magnetic field measurement. This method can control absorption of optical pumping light, which is benefit for improving the uniformity of alkali metal atoms polarization and the sensitivity of atomic magnetometer. In addition, it allows optical pumping in the absence of quenching gas. We conduct experiments with a hybrid optically pumped atomic magnetometer using a cell containing potassium and rubidium. By adjusting the density ratio of alkali metal and the pumping laser conditions, we measured the magnetic field sensitivity better than 0.7 fT/sqrt(Hz).

  4. Trion and dimer formation in three-color fermions

    Science.gov (United States)

    Pohlmann, J.; Privitera, A.; Titvinidze, I.; Hofstetter, W.

    2013-02-01

    We study the problem of three ultracold fermions in different hyperfine states loaded into a lattice with spatial dimension D=1,2. We consider SU(3)-symmetric attractive interactions and also eventually include a three-body constraint, which mimics the effect of three-body losses in the strong-loss regime. We combine exact diagonalization with the Lanczos algorithm, and evaluate both the eigenvalues and the eigenstates of the problem. In D=1, we find that the ground state is always a three-body bound state (trion) for arbitrarily small interaction, while in D=2, due to the stronger influence of finite-size effects, we are not able to provide conclusive evidence of the existence of a finite threshold for trion formation. Our data are, however, compatible with a threshold value which vanishes logarithmically with the size of the system. Moreover, we are able to identify the presence of a fine structure inside the spectrum, which is associated with off-site trionic states. The characterization of these states shows that only the long-distance behavior of the eigenstate wave functions provides clear-cut signatures about the nature of bound states and that on-site observables are not enough to discriminate between them. The inclusion of a three-body constraint due to losses promotes these off-site trions to the role of lowest-energy states, at least in the strong-coupling regime.

  5. PUMPS

    Science.gov (United States)

    Thornton, J.D.

    1959-03-24

    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  6. A plateau in the sensitivity of a compact optically pumped atomic magnetometer

    Directory of Open Access Journals (Sweden)

    Natsuhiko Mizutani

    2014-05-01

    Full Text Available In a compact optically pumped atomic magnetometer (OPAM, there is a plateau in the sensitivity where the dependence of the sensitivity on pumping power is small compared with that predicted by the uniform polarization model. The mechanism that generates this plateau was explained by numerical analysis. The distribution of spin polarization in the alkali metal cell of an OPAM was modeled using the Bloch equation incorporating a diffusion term and an equation for the attenuation of the pump beam. The model was well-fitted to the experimental results for a module with a cubic cell with 20 mm sides and pump and probe beams with 8 mm diameter. On the plateau, strong magnetic response was generated at the regions that were not illuminated directly by the intense pump beam, while at the same time spin polarization as large as 0.5 was maintained due to diffusion of the spin-polarized atoms. Thus, the sensitivity of the magnetometer monitored with a probe beam decreases only slightly with increasing pump beam intensity because the spin polarization under an intense pump beam is saturated. This plateau, which is characteristic of this type of magnetometer using a narrow pump and probe beams, can be used in arrays of magnetometers because it enables stable operation with little sensitivity fluctuation from changes in pump beam power.

  7. Multipass diode-pumped solid-state optical amplifier

    Science.gov (United States)

    Plaessmann, Henry; Re, Sean A.; Alonis, Joseph J.; Vecht, David L.; Grossman, William M.

    1993-01-01

    A new diode-pumped solid-state multipass amplifier produced 38-dB small-signal gain at 1.047 micron in Nd:YLF with 1.6-W pump power and 37 percent extraction efficiency near saturation. The amplifier had a 1:1 confocally reimaging multipass design that generated both high gain and high efficiency. The same amplifier design with 13 W of pump power was tested with Nd:YAG at 1.064 micron, which gave 38-dB small-signal gain and 3.2 W of output power, and with Nd:YVO4, also at 1.064 micron, which gave greater than 50-dB small-signal gain and 4.3 W of output power.

  8. Asymmetric optical nuclear spin pumping in a single uncharged quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Klotz, Florian; Jovanov, Vase; Kierig, Johannes; Clark, Emily; Bichler, Max; Abstreiter, Gerhard; Brandt, Martin; Finley, Jonathan [Walter Schottky Institut, Technische Universitaet Muenchen, Garching (Germany); Schwager, Heike; Giedke, Geza [Max-Planck-Institut fuer Quantenoptik, Garching (Germany)

    2011-07-01

    We present the observation of a unipolar optically pumped dynamic nuclear polarization (DNP) in a single self assembled InGaAs quantum dot (QD). Electrons are resonantly excited in the QD and polarize the nuclear spin system via the hyperfine contact coupling, creating an Overhauser magnetic field. Remarkably, we observe a strong asymmetry in nuclear spin pumping for excitation of the two Zeeman-split neutral exciton states. Hereby, pumping the higher energy Zeeman branch effectively polarizes the nuclear spin system, whereas the lower energy branch does not. We also find a characteristic dependence of the observed DNP on the applied magnetic field where optically induced nuclear spin pumping is most efficient for an intermediate regime of 4-6 T, with a polarization of the nuclear spin bath of 53%. A theoretical model is developed that successfully explains the empirically found features based on the exciton level structure of the system.

  9. Synchronous pumping of picosecond dye laser using high efficiency second harmonic generation from optical fibres

    Science.gov (United States)

    Lawandy, N. M.; Bernardin, J. P.; Macdonald, R. L.; Demouchy, G.

    1991-01-01

    The stable operation of a mode-locked dye laser synchronously pumped by the second harmonic of an Nd:YAG laser produced in an Nd codoped germanosilicate optical fiber is reported. The optical fiber preparation technique, which results in a second harmonic conversion efficiency of 2 percent, is described. This optical fiber SHG conversion efficiency is the highest reported to date using a continuous-wave mode-locked laser.

  10. Nd:GGG disk laser with multipoint spatially periodic optical pumping

    Science.gov (United States)

    Guryev, D. A.; Nikolaev, D. A.; Tsvetkov, V. B.

    2016-04-01

    The results of the study of the output laser beam spatial characteristics of the Nd:Gd3Ga5O12 (Nd:GGG) disk laser with multipoint spatially periodic diode-pumping are presented. The presence of the optical coupling between the TEM00 lasing channels is demonstrated. The phase-locking of channels was realized due to partial overlapping of laser beams inside the pumped areas of the active element disk.

  11. PUMP-TUNING KTP OPTICAL PARAMETRIC OSCILLATOR WITH CONTINUOUS OUTPUT WAVELENGTH PUMPED BY A PULSED TUNABLE Ti:SAPPHIRE LASER

    Institute of Scientific and Technical Information of China (English)

    DING XIN; YAO JIAN-QUAN; YU YI-ZHONG; YU XUAN-YI; XU JING-JUN; ZHANG GUANG-YIN

    2001-01-01

    We report on the implementation of a KTP optical parametric oscillator pumped by a pulsed tunable Ti:sapphire laser. Two major improvements were achieved, including the connection of the signal and idler tuning ranges and the high-output conversion efficiency through the signal and idler tuning ranges. Both in the signal and idler, the continuous output wavelength from 1.261 to 2.532μm was obtained by varying the pump wavelength from 0.7 to 0.98μm. The maximum output pulse energy was 27.2mJ and the maximum conversion efficiency was 35.7% at 1.311μm (signal).

  12. Optimizations of spin-exchange relaxation-free magnetometer based on potassium and rubidium hybrid optical pumping.

    Science.gov (United States)

    Fang, Jiancheng; Wang, Tao; Zhang, Hong; Li, Yang; Zou, Sheng

    2014-12-01

    The hybrid optical pumping atomic magnetometers have not realized its theoretical sensitivity, the optimization is critical for optimal performance. The optimizations proposed in this paper are suitable for hybrid optical pumping atomic magnetometer, which contains two alkali species. To optimize the parameters, the dynamic equations of spin evolution with two alkali species were solved, whose steady-state solution is used to optimize the parameters. The demand of the power of the pump beam is large for hybrid optical pumping. Moreover, the sensitivity of the hybrid optical pumping magnetometer increases with the increase of the power density of the pump beam. The density ratio between the two alkali species is especially important for hybrid optical pumping magnetometer. A simple expression for optimizing the density ratio is proposed in this paper, which can help to determine the mole faction of the alkali atoms in fabricating the hybrid cell before the cell is sealed. The spin-exchange rate between the two alkali species is proportional to the saturated density of the alkali vapor, which is highly dependent on the temperature of the cell. Consequently, the sensitivity of the hybrid optical pumping magnetometer is dependent on the temperature of the cell. We proposed the thermal optimization of the hybrid cell for a hybrid optical pumping magnetometer, which can improve the sensitivity especially when the power of the pump beam is low. With these optimizations, a sensitivity of approximately 5 fT/Hz(1/2) is achieved with gradiometer arrangement.

  13. High-power optically pumped semiconductor laser apllications

    Science.gov (United States)

    Morioka, S. Brandon

    2011-03-01

    OPS lasers have found applications in various industrial and scientific laser applications due to their power scaling capability, their wide range of emission wavelengths, physical size and their superior reliability. This paper provides an overview of commercially available OPS lasers and the applications in which they are used including biotechnology, medical, holography, Titanium-Sapphire laser pumping, non-lethal defense, forensics, and entertainment.

  14. Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

    2013-01-01

    We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...

  15. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    Energy Technology Data Exchange (ETDEWEB)

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G., E-mail: gaetano.mileti@unine.ch [Laboratoire Temps-Fréquence, University of Neuchâtel, Neuchâtel 2000 (Switzerland); Shea, H. [Microsystems for Space Technologies Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel 2002 (Switzerland)

    2014-02-03

    Miniature (optical pumping of alkali atoms, such as atomic clocks and magnetometers, today mostly employ vertical-cavity surface-emitting lasers as pump light sources. Here, we report on the demonstration of optical pumping in a microfabricated alkali vapor resonance cell using (1) a microfabricated Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm{sup 3} as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm{sup 3} volume) test setup based on the M{sub z} magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors.

  16. Optical Fiber Pumped High Repetition Rate and High Power Nd:YVO4 Picosecond Regenerative Amplifier

    Directory of Open Access Journals (Sweden)

    Zhen-Ao Bai

    2015-08-01

    Full Text Available We report a stable optical fiber pumped Nd:YVO4 all solid state regenerative amplifier with all fiber picosecond laser as seed source. 888 nm Yb optical fiber lasers was chosen as pump source to reduce quantum defect for improved thermal performance. At the repetition rate of 99.6 kHz, maximum power of 19.63 W with 36 ps pulse duration were achieved when seeded by a 150 mW picosecond oscillator. The wavelength delivered was 1064.07 nm with spectral width of 0.14 nm.

  17. Production of polarized negative deuterium ion beam with dual optical pumping in KEK

    Energy Technology Data Exchange (ETDEWEB)

    Kinsho, M.; Ikegami, K.; Takagi, A. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Mori, Y.

    1997-02-01

    To obtain highly nuclear-spin vector polarized negative deuterium ion beam, a dual optically pumped polarized negative deuterium ion source has been developed at KEK. It is possible to select a pure nuclear-spin state with this scheme, and negative deuterium ion beam with 100% nuclear-spin vector polarization can be produced in principle. We have obtained about 70% of nuclear-spin vector polarized negative deuterium ion beam so far. This result may open up a new possibilities for the optically pumped polarized ion source. (author)

  18. The implementation of high speed digital PSD in optically pumping magnetometers

    Science.gov (United States)

    Chen, Jun; Cheng, Defu; Zhou, Zhijian; Ma, Ming; Wang, Chao; Hu, Ruifan

    2017-01-01

    The 4He optically pumping magnetometer is a kind of high resolution instrument for measuring magnetic field intensity. Its response speed cannot meet the requirements in some experiments. By analyzing many factors, Phase Sensitive Detector (PSD) which is the key part of the lock-in amplifier processes data at a very slow speed is found. To improve its performance, this paper introduces a parallel digital phase sensitive detector based on coordinate rotation digital computer (CORDIC) algorithm. The cost time of the parallel digital phase sensitive detector is only 5.1% of the previous one. It can greatly enhance the response speed of the 4He optically pumping magnetometer.

  19. Digital Square-Wave Frequency Modulated Microwave Sources for a Miniature Optically Pumped Cesium Beam Clock

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; ZHU Chengjin; LIU Ge; WANG Fengzhi; WANG Yiqiu; YANG Donghai

    2001-01-01

    Three different digital frequencymodulated microwave sources have been designed andapplied to our miniature optically pumped cesiumbeam clock.The main features and their influenceon clock accuracy have been experimentally tested.Itis proved that a digital square-wave frequency modu-lated microwave source using a microprocessor con-trolled direct-digital frequency synthesizer (DDFS)for our miniature optically pumped cesium beamclock works well,the frequency short term stability2 × 10 11/x r and the long term stability 3.5 x 10-13 forone day sample time have been obtained.

  20. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    Energy Technology Data Exchange (ETDEWEB)

    Chamorovskiy, A Yu; Okhotnikov, Oleg G [Optoelectronics Research Center, Tampere University of Technology, Tampere (Finland)

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  1. Bimolecular Recombination Kinetics of an Exciton-Trion Gas

    Science.gov (United States)

    2015-07-01

    The second and third reactions are catalytic agents for the loss of excitons. This implies that the constants R and S will appear only in the exciton...change the electron density. 3 Note that Reaction 3 in Table 2 is catalytic as defined above, because it changes the electron and e−trion...from the PL laser, which is fixed. Table 2 Reactions that change νe Reaction Rate Constant 1. νe + νh → ϕ A 2. νe + τh → Ex P 3

  2. Performance comparison of bismuth/erbium co-doped optical fibre by 830 nm and 980 nm pumping

    Science.gov (United States)

    Yan, Binbin; Luo, Yanhua; Zareanborji, Amirhassan; Xiao, Gui; Peng, Gang-Ding; Wen, Jianxiang

    2016-10-01

    The performance of bismuth/erbium co-doped fibre (BEDF) by 830 nm and 980 nm pumping has been studied in detail, including the small signal absorption, pump absorption, emission, gain and excited state absorption (ESA). Based on the study, energy transition diagrams of BEDF under 830 nm or 980 nm pumping are proposed to clarify the spectroscopic properties. The results demonstrate the advantages of 830 nm pumping for BEDF over 980 nm pumping when considering the absorption, pumping efficiency, excited state absorption and optical amplification.

  3. Stable 811.53 nm diode laser pump source for optically pumped metastable Ar laser

    Science.gov (United States)

    Gao, Jun; Zuo, Duluo; Zhao, Jun; Li, Bin; Yu, Anlan; Wang, Xinbing

    2016-10-01

    A stable external cavity diode laser coupled with volume Bragg grating for metastable argon atoms pumping is presented. The measured maximum output power of the continuous wave is 6.5 W when the spectral width (FWHM) is less than 21 pm around 811.53 nm and the power efficiency is 68%. The tuning range of the emission wavelength is bigger than 270 pm. The calculated deviation in relative absorption efficiency caused by the fluctuations of wavelength and power is less than 4%.

  4. 1300 nm optically pumped quantum dot spin vertical external-cavity surface-emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Orchard, J. [Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Clarke, E. [EPSRC National Centre for III-V Technologies, University of Sheffield, Mappin Street, S1 3JD Sheffield (United Kingdom)

    2015-10-12

    We report a room temperature optically pumped Quantum Dot-based Spin-Vertical-External-Cavity Surface-Emitting laser (QD Spin-VECSEL) operating at the telecom wavelength of 1.3 μm. The active medium was composed of 5 × 3 QD layers; each threefold group was positioned at an antinode of the standing wave of the optical field. Circularly polarized lasing in the QD-VECSEL under Continuous-Wave optical pumping has been realized with a threshold pump power of 11 mW. We further demonstrate at room temperature control of the QD-VECSEL output polarization ellipticity via the pump polarization.

  5. Pump-phase-noise-free optical wavelength data exchange between QAM signals with 50-GHz channel-spacing using coherent DFB pump.

    Science.gov (United States)

    Lu, Guo-Wei; Albuquerque, André; Puttnam, Benjamin J; Sakamoto, Takahide; Drummond, Miguel; Nogueira, Rogério; Kanno, Atsushi; Shinada, Satoshi; Wada, Naoya; Kawanishi, Tetsuya

    2016-02-22

    An important challenge for implementing optical signal processing functions such as wavelength conversion or wavelength data exchange (WDE) is to avoid the introduction of linear and nonlinear phase noise in the subsystem. This is particularly important for phase noise sensitive, high-order quadrature-amplitude modulation (QAM) signals. In this paper, we propose and experimentally demonstrate an optical data exchange scheme through cascaded 2nd-order nonlinearities in periodically-poled lithium niobate (PPLN) waveguides using coherent pumping. The proposed coherent pumping scheme enables noise from the coherent pumps to be cancelled out in the swapped data after WDE, even with broad linewidth distributed feedback (DFB) pump lasers. Hence, this scheme allows phase noise tolerant processing functions, enabling the low-cost implementation of WDE for high-order QAM signals. We experimentally demonstrate WDEs between 10-Gbaud 4QAM (4QAM) signal and 12.5-Gbaud 4QAM (16QAM) signal with 3.5-MHz linewidth DFB pump lasers and 50-GHz channel spacing. Error-free operation is observed for the swapped QAM signals with coherent DFB pumping whilst use of free-running DFB pumps leads to visible error floors and unrecoverable phase errors. The phase noise cancellation in the coherent pump scheme is further confirmed by study of the recovered carrier phase of the converted signals. In addition to pump phase noise, the influence of crosstalk caused by the finite extinction ratio in WDE is also experimentally investigated for the swapped QAM signals.

  6. High-repetition-rate picosecond pump laser based on a Yb:YAG disk amplifier for optical parametric amplification.

    Science.gov (United States)

    Metzger, Thomas; Schwarz, Alexander; Teisset, Catherine Yuriko; Sutter, Dirk; Killi, Alexander; Kienberger, Reinhard; Krausz, Ferenc

    2009-07-15

    We report an optically synchronized picosecond pump laser for optical parametric amplifiers based on an Yb:YAG thin-disk amplifier. At 3 kHz repetition rate, pulse energies of 25 mJ with 1.6 ps pulse duration were achieved with an rms fluctuation in pulse energy of pumped regenerative amplifier.

  7. Increasing the pump-up rate to polarize 3He gas using spin-exchange optical pumping method

    Science.gov (United States)

    Lee, Wai Tung; Tong, Xin; Rich, Dennis; Liu, Yun; Fleenor, Michael; Ismaili, Akbar; Pierce, Joshua; Hagen, Mark; Dadras, Jonny; Robertson, J. Lee

    2009-09-01

    In recent years, polarized 3He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3He to 70% polarization would require 20-40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3He gas using the SEOP method.

  8. Two-mode optical state truncation and generation of maximally entangled states in pumped nonlinear couplers

    CERN Document Server

    Miranowicz, A; Miranowicz, Adam; Leonski, Wieslaw

    2006-01-01

    Schemes for optical-state truncation of two cavity modes are analysed. The systems, referred to as the nonlinear quantum scissors devices, comprise two coupled nonlinear oscillators (Kerr nonlinear coupler) with one or two of them pumped by external classical fields. It is shown that the quantum evolution of the pumped couplers can be closed in a two-qubit Hilbert space spanned by vacuum and single-photon states only. Thus, the pumped couplers can behave as a two-qubit system. Analysis of time evolution of the quantum entanglement shows that Bell states can be generated. A possible implementation of the couplers is suggested in a pumped double-ring cavity with resonantly enhanced Kerr nonlinearities in an electromagnetically-induced transparency scheme. The fragility of the generated states and their entanglement due to the standard dissipation and phase damping are discussed by numerically solving two types of master equations.

  9. Diode-pumped intracavity optical parametric oscillator in pulsed and continuous-wave operation

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Skettrup, Torben; Petersen, O.B.;

    2002-01-01

    An intracavity optical parametric oscillator is investigated in pulsed and continuous-wave operation. The intracavity optical parametric oscillator is based on Yb:YAG as the laser material and a periodically poled lithium niobate crystal as the nonlinear material. Tuneable idler output powers above...... 200 mW are obtained in both modes of operation with 13.5 W of incident diode pump power. The idler output was tuned in the wavelength range 3820-4570 nm....

  10. Optical silencing of C. elegans cells with light-driven proton pumps.

    Science.gov (United States)

    Okazaki, Ayako; Takahashi, Megumi; Toyoda, Naoya; Takagi, Shin

    2014-08-01

    Recent development of optogenetic techniques, which utilize light-driven ion channels or ion pumps for controlling the activity of excitable cells, has greatly facilitated the investigation of nervous systems in vivo. A new generation of optical silencers includes outward-directed proton pumps, such as Arch, which have several advantages over currently widely used halorhodopsin (NpHR). These advantages include the resistance to inactivation during prolonged illumination and the ability to generate a larger optical current from low intensity light. C. elegans, with its small transparent body and well-characterized neural circuits, is especially suitable for optogenetic analyses. In this article, we will outline the practical aspects of using of Arch and other proton pumps as optogenetic tools in C. elegans.

  11. High-power, high repetition-rate, green-pumped, picosecond LBO optical parametric oscillator.

    Science.gov (United States)

    Kienle, Florian; Teh, Peh Siong; Lin, Dejiao; Alam, Shaif-Ul; Price, Jonathan H V; Hanna, D C; Richardson, David J; Shepherd, David P

    2012-03-26

    We report on a picosecond, green-pumped, lithium triborate optical parametric oscillator with record-high output power. It was synchronously pumped by a frequency-doubled (530 nm), pulse-compressed (4.4 ps), high-repetition-rate (230 MHz), fiber-amplified gain-switched laser diode. For a pump power of 17 W, a maximum signal and idler power of 3.7 W and 1.8 W was obtained from the optical parametric oscillator. A signal pulse duration of ~3.2 ps was measured and wide tunability from 651 nm to 1040 nm for the signal and from 1081 nm to 2851 nm for the idler was achieved.

  12. Method for optical pumping of thin laser media at high average power

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E. (Livermore, CA); Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Payne, Stephen A. (Castro Valley, CA)

    2004-07-13

    A thin, planar laser material is bonded to a light guide of an index-matched material forming a composite disk. Diode array or other pump light is introduced into the composite disk through the edges of the disk. Pump light trapped within the composite disk depletes as it multi-passes the laser medium before reaching an opposing edge of the disk. The resulting compound optical structure efficiently delivers concentrated pump light and to a laser medium of minimum thickness. The external face of the laser medium is used for cooling. A high performance cooler attached to the external face of the laser medium rejects heat. Laser beam extraction is parallel to the heat flux to minimize optical distortions.

  13. An optically pumped GaN/AlGaN quantum well intersubband terahertz laser

    Science.gov (United States)

    Fu, Ai-Bing; Hao, Ming-Rui; Yang, Yao; Shen, Wen-Zhong; Liu, Hui-Chun

    2013-02-01

    We propose an optically pumped nonpolar GaN/AlGaN quantum well (QW) active region design for terahertz (THz) lasing in the wavelength range of 30 μm ~ 40 μm and operating at room temperature. The fast longitudinal optical (LO) phonon scattering in GaN/AlGaN QWs is used to depopulate the lower laser state, and more importantly, the large LO phonon energy is utilized to reduce the thermal population of the lasing states at high temperatures. The influences of temperature and pump intensity on gain and electron densities are investigated. Based on our simulations, we predict that with a sufficiently high pump intensity, a room temperature operated THz laser using a nonpolar GaN/AlGaN structure is realizable.

  14. Zeeman effect and optical pumping in atomic rubidium: a teaching experiment in quantum physics

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, R.J.; Adams, S.; Seddon, G.; Golby, J.A.; Massey, D.R.

    1987-01-01

    The authors describe an experiment developed recently in an undergraduate laboratory to measure the Zeeman splitting of the ground state of atomic rubidium. An optical pumping technique is employed and the magnetic field is calibrated by using free-electron spin resonance. Multiphoton absorption and power broadening of transitions are also investigated and a number of quantum principles introduced experimentally.

  15. Dual-pump wave mixing in semiconductor optical amplifiers: performance enhancement with long amplifiers

    Science.gov (United States)

    Tomkos, Ioannis; Zacharopoulos, Ioannis; Syvridis, Dimitrios

    1999-05-01

    We demonstrate experimentally the improvement of the performance of the dual pump wave mixing scheme in semiconductor optical amplifiers, using long amplifier chips and high optical pump powers. The optical amplifiers used in the experiment had a ridge waveguide structure with bulk active layer and antireflective-coated angled facets. Measurements of the conversion efficiency and SBR as a function of wavelength shift are presented for a wavelength shift of more than 40 nm. The above measurements are carried out for three amplifier lengths (500 micrometers , 1000 micrometers , and 1500 micrometers ) and for different levels of the optical power of the two pumps. It will be shown that an increase in the amplifier length from 500 micrometers to 1500 micrometers results to an increase of more than 25 dB for the efficiency and more than 20 dB for the SBR. This improvement combined with the inherent advantages of the dual pump scheme (almost constant SBR and high efficiency for large wavelength shifts) results in a highly performing wavelength converter/phase conjugator, suitable for many applications.

  16. Investigation of a diode-pumped intracavity optical parametric oscillator in pulsed and continuous wave operation

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Skettrup, Torben; Balle-Petersen, O.;

    2001-01-01

    Summary form only given. CW and pulsed compact tunable laser sources in the infrared have widespread scientific, medical and industrial applications. Such a laser source can be obtained by use of a diode-pumped intracavity optical parametric oscillator (IOPO). We report on a IOPO based on a Yb...

  17. Continuous-wave Optically Pumped Lasing of Hybrid Perovskite VCSEL at Green Wavelength

    KAUST Repository

    Alias, Mohd Sharizal

    2017-05-08

    We demonstrate the lasing of a perovskite vertical-cavity surface-emitting laser at green wavelengths, which operates under continuous-wave optical pumping at room-temperature by embedding hybrid perovskite between dielectric mirrors deposited at low-temperature.

  18. Simulation of a tunable optically pumped terahertz intersubband laser with diluted magnetic semiconductors

    NARCIS (Netherlands)

    Popadić, M.; Milanović, V.; Ikonić, Z.; Indijn, D.

    2006-01-01

    A simulation of an optically pumped laser based on a ZnSe/Zn1−yCdySe double quantum well with a Zn1−xMnxSe diluted magnetic semiconductor barrier is presented. Giant Zeeman splitting in diluted magnetic semiconductors leads to splitting of electronic states, which in turn leads to tunability of lase

  19. Reliable Optical Pump Architecture for Highly Coherent Lasers Used in Space Metrology Applications

    Science.gov (United States)

    Erlig, Herman; Qiu, Yueming; Poberezhskiy, Ilya Y.; Meras, Patrick L.; Chang, Daniel H.; Wu, Yen-Hung

    2012-01-01

    The design and initial demonstration of a laser pump module (LPM) incorporating single-mode, grating-stabilized 808-nm diode lasers and a low-loss, high-port-count optical combiner are completed. The purpose of the developed LPM is to reliably pump an Nd:YAG crystal in the laser head (LH), which serves as the optical metrology source for SIMLite mission. Using the narrow-linewidth, single-mode laser diodes enables placement of the pump power near Nd adsorption peak, which enhances pumping efficiency. Grating stabilization allows for stable pump spectra as diode operating temperature and bias current change. The low-loss, high-port-count optical combiner enables efficient combining of tens of pumps. Overall, the module supports 5+ years of continuous operation at 2 W of pump power with reliability approaching 100 percent. The LPM consists of a laser diode farm (LDF) and a pump beam combiner (PBC). An array of 807- to 808-nm fiber-pigtailed laser diodes makes up the LDF. A Bragg grating in each 5- m core single-mode (SM) fiber pigtail acts to stabilize the lasing spectra over a range of diode operating conditions. These commercially available single-mode laser diodes can deliver up to 150 mW of optical power. The outputs from the multiple pumps in the LDF are routed to the PBC, which is a 37-input by 1-output all-fiber device. The input ports consist of 5- m core SM fiber, while the output port consists of 105- m core, 0.15 NA (numerical aperture) multi-mode (MM) fiber. The combiner is fabricated by fusing the 37 input fibers while simultaneously tapering the fused region. At the completion of this process, the MM fiber is spliced to the end of the adiabatic taper, and, for protection, the combiner is sheathed by a capillary tube. A compact and robust metal housing was designed and fabricated to protect the PBC during space deployment.

  20. Ultrafast optical beam deflection in a pump probe configuration

    Science.gov (United States)

    Liang, Lingliang; Tian, Jinshou; Wang, Tao; Wu, Shengli; Li, Fuli; Wang, Junfeng; Gao, Guilong

    2016-09-01

    Propagation of a signal beam in an AlGaAs/GaAs waveguide multiple-prism light deflector is theoretically investigated by solving the scalar Helmholtz equation to obtain the dependences of the temporal and spatial resolvable characteristics of the ultrafast deflector on the material dispersion of GaAs including group velocity dispersion and angular dispersion, interface reflection, and interface scattering of multiple-prism deflector. Furthermore, we experimentally confirm that, in this ultrafast beam deflection device, the deflecting angle of the signal light beam is linear with the pump fluence and the temporal resolution of the ultrafast deflection is 10 ps. Our results show that the improvement of the temporal and spatial resolvable performances is possible by properly choosing the structural parameters and enhancing the quality of the device. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274377 and 61176006) and the State Major Research Equipment Project, China (Grant No. ZDY2011-2).

  1. Nonlinear effects in optical pumping of a cold and slow atomic beam

    KAUST Repository

    Porfido, N.

    2015-10-12

    By photoionizing hyperfine (HF) levels of the Cs state 62P3/2 in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180μs) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of “dark” and “bright” resonances leading to power-dependent branching coefficients.

  2. Effects of chirp of pump pulses on broadband terahertz pulse spectra generated by optical rectification

    Science.gov (United States)

    Hamazaki, Junichi; Furusawa, Kentaro; Sekine, Norihiko; Kasamatsu, Akifumi; Hosako, Iwao

    2016-11-01

    The effects of the chirp of the pump pulse in broadband terahertz (THz) pulse generation by optical rectification (OR) in GaP were systematically investigated. It was found that the pre-compensation for the dispersion of GaP is important for obtaining smooth and single-peaked THz spectra as well as high power-conversion efficiency. It was also found that an excessive amount of chirp leads to distortions in THz spectra, which can be quantitatively analyzed by using a simple model. Our results highlight the importance of accurate control over the chirp of the pump pulse for generating broadband THz pulses by OR.

  3. Acquisition of a Nd-Yag Pumped MOPO (Master Oscillator/Power Oscillator) Optical Parametric Oscillator

    Science.gov (United States)

    1997-09-30

    SEP 1997 2. REPORT TYPE 3. DATES COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Acquisition of a Nd-Yag Pumped MOPO (Master Oscillator...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 ACQUISITION OF A ND-YAG PUMPED MOPO (MASTER OSCILLATOR / POWER OSCILLATOR) OPTICAL...instrument is configured in a master oscillator/power oscillator configuration, hence the designation MOPO . The MOPO will be used in conjunction

  4. Dual correlated pumping scheme for phase noise preservation in all-optical wavelength conversion.

    Science.gov (United States)

    Anthur, Aravind P; Watts, Regan T; Shi, Kai; Carroll, John O'; Venkitesh, Deepa; Barry, Liam P

    2013-07-01

    We study the effect of transfer of phase noise in different four wave mixing schemes using a coherent phase noise measurement technique. The nature of phase noise transfer from the pump to the generated wavelengths is shown to be independent of the type of phase noise (1 / f or white noise frequency components). We then propose a novel scheme using dual correlated pumps to prevent the increase in phase noise in the conjugate wavelengths. The proposed scheme is experimentally verified by the all-optical wavelength conversion of a DQPSK signal at 10.7 GBaud.

  5. Out-of-plane resonances in terahertz photonic crystal slabs modulated by optical pumping.

    Science.gov (United States)

    Shi, Yulei; Zhou, Qing-Li; Liu, Wei; Zhang, Cunlin

    2011-10-10

    This paper describes detailed optical-pump-terahertz-probe studies of two-dimensional photonic crystal slabs for propagation perpendicular to the slabs. When the slabs are excited by an 800 nm pump pulse and the effect of shielding by photocarriers is removed, we find that the decaying tail in the transmitted terahertz radiation is strikingly enhanced. The photocarriers weaken guided resonances, but they also greatly enhance the excitation efficiency of guided resonances and the ability of the guided resonances to transfer energy back to the radiation field. This increases the resonance-assisted contribution to transmitted field. The photoinduced resonant extremes agree well with the Fano model.

  6. A Sensitive Scheme to Observe Weak Photo-Refraction Effects in Some Nonlinear Optical Crystals Pumped by Ultrashort Optical Pulses

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang; GAO Yan-Xia; CAI Hua; LI Jing-Zhen

    2009-01-01

    We present a sensitive scheme, for the first time to our knowledge, to observe photo-refraction (PR) effects in some nonlinear optical crystals, e.g.β-BBO, LBO and BIBO, pumped by an intense ultrashort laser pulse chain. These quite weak effects are "amplified" by sensitive cw intracavity loss modulation. Our results show that they are repeatable and are dependent on pumping power and wavelength, and their response time ranges from tens of seconds to several minutes. The recorded dynamical transitions between the self-focusing to the self-defocusing (or vice versa) induced by the PR effect may be critically important for us to give more insight into the stability of some cascade nonlinear frequency conversions, e.g. multi-stage optical parametric amplifiers.

  7. Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

    Directory of Open Access Journals (Sweden)

    Kai Braun

    2015-05-01

    Full Text Available Here, we demonstrate a bias-driven superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than electroluminescence induced by inelastic tunneling without optical pumping. A positive, steadily increasing bias voltage induces a step-like rise of the Stokes shifted optical signal emitted from the junction. This emission is strongly attenuated by reversing the applied bias voltage. At high bias voltage, the emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode into the highest occupied orbital of the closest substrate-bound molecule (lower level and radiative recombination with an electron from above the Fermi level (upper level, hence feeding photons back by stimulated emission resonant with the gap mode. The system reflects many essential features of a superluminescent light emitting diode.

  8. Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons.

    Science.gov (United States)

    Braun, Kai; Wang, Xiao; Kern, Andreas M; Adler, Hilmar; Peisert, Heiko; Chassé, Thomas; Zhang, Dai; Meixner, Alfred J

    2015-01-01

    Here, we demonstrate a bias-driven superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip) of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than electroluminescence induced by inelastic tunneling without optical pumping. A positive, steadily increasing bias voltage induces a step-like rise of the Stokes shifted optical signal emitted from the junction. This emission is strongly attenuated by reversing the applied bias voltage. At high bias voltage, the emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode) into the highest occupied orbital of the closest substrate-bound molecule (lower level) and radiative recombination with an electron from above the Fermi level (upper level), hence feeding photons back by stimulated emission resonant with the gap mode. The system reflects many essential features of a superluminescent light emitting diode.

  9. Measurements of linear and circular birefringence in metals by femtosecond optical pump-probe spectroscopy

    CERN Document Server

    Wilks, R

    2002-01-01

    Optically induced transient linear and circular birefringence has been studied in three different materials: ferromagnetic Ni, semiconducting GaAs and the non-magnetic metal Al. A pump-probe experiment with sub-ps resolution was set up for this purpose. The time-resolved reflectivity, rotation and ellipticity of the reflected probe beam were recorded after pumping with light of variable helicity. In the Ni sample an ultrafast demagnetisation effect was observed and the variation of the rotation and ellipticity on sub-picosecond time scales was compared. Rotation and ellipticity were found to have a similar time dependence. In GaAs, optical orientation of spin was achieved and the subsequent spin relaxation was measured for different pump powers. Fitting of the optical rotation data has revealed the power dependence of the various decay constants. In the Al sample a small signal was observed that decays on ps time scales. This was attributed to a linear birefringence effect resulting from a cubic optical nonli...

  10. Light amplification by stimulated emission from an optically pumped molecular junction in a scanning tunneling microscope

    CERN Document Server

    Braun, K; Wang, X; Adler, H; Peisert, H; Chasse, T; Zhang, D; Meixner, A J

    2013-01-01

    Here, we introduce and experimentally demonstrate optical amplification and stimulated emission from a single optically pumped molecular tunneling junction of a scanning tunneling microscope. The gap between a sharp gold tip and a flat gold substrate covered with a self-assembled monolayer of 5-chloro-2-mercaptobenzothiazole molecules forms an extremely small optical gain medium. When electrons tunnel from the molecules highest occupied molecular orbital to the tip, holes are left behind. These can be repopulated by hot electrons induced by the laser-driven plasmon oscillation on the metal surfaces enclosing the cavity. Solving the laser-rate equations for this system shows that the repopulation process can be efficiently stimulated by the gap modes near field, TERS scattering from neighboring molecules acting as an optical seed. Our results demonstrate how optical enhancement inside the plasmonic cavity can be further increased by a stronger localization via tunneling through molecules. We anticipate that st...

  11. Development of an optically pumped atomic magnetometer using a K-Rb hybrid cell and its application to magnetocardiography

    Directory of Open Access Journals (Sweden)

    Yosuke Ito

    2012-09-01

    Full Text Available We have developed an optically pumped atomic magnetometer using a hybrid cell of K and Rb. The hybrid optical pumping technique can apply dense alkali-metal vapor to the sensor head and leads to high signal intensity. We use dense Rb vapor as probed atoms, and achieve a sensitivity of approximately 100 fTrms/Hz1/2 around 10 Hz. In this case, the sensitivity is limited by the system noise, and the magnetic linewidth is narrower than that for direct Rb optical pumping. We demonstrated magnetocardiography using the magnetometer and obtained clear human magnetocardiograms.

  12. Image transmission in mid-IR using a solid state laser pumped optical parametric oscillator

    Science.gov (United States)

    Prasad, Narasimha S.; Kratovil, Pat; Magee, James R.

    2002-04-01

    In this paper, image transmission using a mid-wave IR (MWIR) optical transceiver based free-space data link under low visibility conditions is presented. The all-solid-state MWIR transceiver primarily consisted of a passively Q-switched, short-pulsed Nd:YAG laser pumping a periodically poled lithium niobate (PPLN) based optical parametric oscillator and a Dember effect detector. The MILES transceiver generates pulse position waveforms. The optical data link consisting of transmitter drive electronics, pulse conditioning electronics and a computer generating pulses compatible with the 2400-baud rate RS232 receiver was utilized. Data formatting and RS232 transmission and reception were achieved using a computer. Data formatting transformed an arbitrary image file format compatible with the basic operation of pump laser. Images were transmitted at a date rate of 2400 kbits/sec with 16 bits/pixel. Test images consisting of 50X40 pixels and 100X80 pixels were transmitted through free-space filled with light fog up to 120 ft. Besides optical parametric oscillators, the proposed concept can be extended to optical parametric amplifiers, Raman lasers and other nonlinear optical devices to achieve multi-functionality.

  13. Optical pump-probe microscopy for biomedicine and art conservation

    Science.gov (United States)

    Fischer, Martin

    2013-03-01

    Nonlinear optical microscopy can provide contrast in highly heterogeneous media and a wide range of applications has emerged, primarily in biology, medicine, and materials science. Compared to linear microscopy methods, the localized nature of nonlinear interactions leads to high spatial resolution, optical sectioning, and larger possible imaging depth in scattering media. However, nonlinear contrast (other than fluorescence, harmonic generation or CARS) is generally difficult to measure because it is overwhelmed by the large background of detected illumination light. This background can be suppressed by using femtosecond pulse or pulse train shaping to encode nonlinear interactions in background-free regions of the frequency spectrum. We have developed this shaping technology to study novel intrinsic structural and molecular contrast in biological tissue, generally using less power than a laser pointer. For example we have recently been able to sensitively measure detailed transient absorption dynamics of melanin sub-types in a variety of skin lesions, showing clinically relevant differences of melanin type and distribution between cancerous and benign tissue.[1] Recently we have also applied this technology to paint samples and to historic artwork in order to provide detailed, depth-resolved pigment identification. Initial studies in different inorganic and organic pigments have shown a rich and pigment-specific nonlinear absorption signature.[2] Some pigments, for example lapis lazuli (natural ultramarine), even show marked differences in signal depending on its geographic origin and on age, demonstrating the potential of this technique to determine authenticity, provenance, technology of manufacture, or state of preservation of historic works of art.

  14. An Optically Pumped Magnetometer Working in the Light-Shift Dispersed Mz Mode.

    Science.gov (United States)

    Schultze, Volkmar; Schillig, Bastian; IJsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Stolz, Ronny

    2017-03-10

    We present an optically pumped magnetometer working in a new operational mode-the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) Mz configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use of small alkali metal vapor cells of identical properties in integrated array structures, where two such cells are pumped by circularly polarized light of opposite helicity; and (4) subtraction of the Mz signals of these two cells. The LSD-Mz magnetometer's performance depends on the inherent and very complex interplay of input parameters. In order to find the configuration of optimal magnetometer resolution, a sensitivity analysis of the input parameters by means of Latin Hypercube Sampling was carried out. The resulting datasets of the multi-dimensional parameter space exploration were assessed by a subsequent physically reasonable interpretation. Finally, the best shot-noise limited magnetic field resolution was determined within that parameter space. As the result, using two 50 mm3 integrated vapor cells a magnetic field resolution below 10 fT/√Hz at Earth's magnetic field strength is possible.

  15. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors.

    Science.gov (United States)

    Euser, Tijmen G; Harding, Philip J; Vos, Willem L

    2009-07-01

    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.

  16. Tunable frequency reference by optical pumping-assisted intracavity V-type electromagnetically induced transparency

    CERN Document Server

    Ying, Kang; Chen, Dijun; Cai, Haiwen; Qu, Ronghui; Gong, Shangqing

    2013-01-01

    A tunable high resolution frequency reference is constructed using the narrowed cavity-linewidth by the optical pumping-assisted V-type electromagnetically induced transparency (EIT). At room temperature, the optical pumping effect will increase the transparency for the V-type EIT and therefore the cavity-linewidth can be narrowed apparently. For the seven EITs observed in our previous study, cavity-linewidth narrowing is observed in all of them. More importantly, we find that the cavity-linewidth can keep at 1.2MHz in a wide frequency range of 100MHz by utilizing the central EIT. This property provides a novel way for constructing high resolution tunable frequency reference via the intracavity EIT.

  17. High-speed switching of biphoton delays through electro-optic pump frequency modulation

    Directory of Open Access Journals (Sweden)

    Ogaga D. Odele

    2017-01-01

    Full Text Available The realization of high-speed tunable delay control has received significant attention in the scene of classical photonics. In quantum optics, however, such rapid delay control systems for entangled photons have remained undeveloped. Here for the first time, we demonstrate rapid (2.5 MHz modulation of signal-idler arrival times through electro-optic pump frequency modulation. Our technique applies the quantum phenomenon of nonlocal dispersion cancellation along with pump frequency tuning to control the relative delay between photon pairs. Chirped fiber Bragg gratings are employed to provide large amounts of dispersion which result in biphoton delays exceeding 30 ns. This rapid delay modulation scheme could be useful for on-demand single-photon distribution in addition to quantum versions of pulse position modulation.

  18. Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor.

    Science.gov (United States)

    Li, Yingying; Wang, Zhiguo; Jin, Shilong; Yuan, Jie; Luo, Hui

    2017-02-20

    Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

  19. Multimode distributed feedback laser emission in a dye-doped optically pumped polymer thin-film

    Science.gov (United States)

    Sobel, F.; Gindre, D.; Nunzi, J.-M.; Denis, C.; Dumarcher, V.; Fiorini-Debuisschert, C.; Kretsch, K. P.; Rocha, L.

    2004-11-01

    We report on particular features of thin film distributed feedback (DFB) lasers. Devices are optically pumped using a Lloyd-mirror interferometer. For a given DFB grating period, the number of lasing modes is film thickness dependent. Spectral content of the devices is analysed using planar waveguide theory. An excellent agreement between the theoretical transverse electric mode structure and the laser emission spectrum is found.

  20. TOWARDS 100% POLARIZATION IN THE OPTICALLY-PUMPED POLARIZED ION SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    ZELENSKI,A.; ALESSI, J.; KOKHANOVSKI, S.; KPONOU, A.; RITTER, B.J.; ZUBETS, V.

    2007-06-25

    The depolarization factors in the multi-step spin-transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically-Pumped Polarized H{sup -} Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86-90%. This contributed to increasing polarization in the AGS and RHIC to 65-70%.

  1. A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers

    Science.gov (United States)

    Larsson, A.; Forouhar, S.; Cody, J.; Lang, R. J.; Andrekson, P. A.

    1990-01-01

    The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.

  2. Study of the metastable helium spin polarization in an optically pumped afterglow

    Science.gov (United States)

    Essabaa, S.; Schearer, L. D.; Arianer, J.; Brissaud, I.; Humblot, H.; Zerhouni, O.

    1994-05-01

    A very efficient technique of optical pumping is applied in order to polarize 2 3S 1 metastable 4He atoms within an afterglow by means of a high power LNA laser. An almost complete atom polarization is achieved. This allows the production of an electron beam of appreciable intensity with high polarization well suited to perform a polarized electron source for linear cw accelerators.

  3. Improved Automatic Filtered Power Control Pumping Method for Uniform Shortpass Band in Optical Fiber Communications

    Science.gov (United States)

    Shen, Jyi-Lai; Huang, Hau-Min; Lee, Yueh-Chien; Huang, Chia-Chih; Lin, Huang-Cuang; Lin, Chin-Yuan

    2009-01-01

    To form a low noise figure and uniform shortpass band in optical fiber communications an improved automatic filtered power control (AFPC) pumping method is proposed here. A modulated single laser signal was entered in a closed feedback loop, in which the erbium-doped fiber amplifier (EDFA) was used as a part of the AFPC loop. Owing to the constant filtered signal and the quadrature phase shift delay inside the feedback loop, an optical pass band was uniformly formed. This EDFA attains high performance with a low noise figure simultaneously. The method was successfully applied to the fabrication of practical 12.0 m length of erbium-doped fiber pumped at 980 nm wavelength and 20 dBm power. Experiments prove that the signal gain of the loop remain flat in the range of 18.2 to 22.4 dB with a worst case error of ±0.5 dB and the noise figure was reduced by 2.2 dB at optimal, which correspond to a shortpass range of 40 nm band pass from 1525 nm to 1565 nm in wavelength. Of course, it should be possible to extent the system performance to all pumping configurations for semiconductor optical amplifiers. This provides the simplest and most economical way to transmit a well-defined band of modulated laser signal and to reject all other unwanted radiation.

  4. Optical pumping effect in absorption imaging of F=1 atomic gases

    CERN Document Server

    Kim, Sooshin; Noh, Heung-Ryoul; Shin, Y

    2016-01-01

    We report our study of the optical pumping effect in absorption imaging of $^{23}$Na atoms in the $F=1$ hyperfine spin states. Solving a set of rate equations for the spin populations under a probe beam, we obtain an analytic expression for the optical signal of the $F=1$ absorption imaging. Furthermore, we verify the result by measuring the absorption spectra of $^{23}$Na Bose-Einstein condensates prepared in various spin states with different probe beam pulse durations. The analytic result can be used in quantitative analysis of $F=1$ spinor condensate imaging and readily applied to other alkali atoms with $I=3/2$ nuclear spin such as $^{87}$Rb.

  5. Beyond Quantum interference and Optical pumping: invoking a Closed-loop phase

    CERN Document Server

    Kani, A

    2016-01-01

    Atomic coherence effects arising from coherent light-atom interaction are conventionally known to be governed by quantum interference and optical pumping mechanisms. However, anisotropic nonlinear response driven by optical field involves another fundamental effect arising from closed-loop multiphoton transitions. This closed-loop phase dictates the tensorial structure of the nonlinear susceptibility as it governs the principal coordinate system in determining, whether the light field will either compete or cooperate with the external magnetic field stimulus. Such a treatment provides deeper understanding of all magneto-optical anisotropic response. The magneto-optical response in all atomic systems is classified using closed-loop phase. The role of quantum interference in obtaining electromagnetically induced transparency or electromagnetically induced absorption in multi-level systems is identified.

  6. High-efficiency mid-infrared ZnGeP2 optical parametric oscillator directly pumped by a lamp-pumped, Q-switched CrTmHo:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; van der Slot, Petrus J.M.; Lindsay, I.D.; Gross, P.; Boller, Klaus J.

    2008-01-01

    We report a singly resonant optical parametric oscillator (SRO) based on a ZnGeP2 crystal directly pumped by a lamp-pumped Q-switched CrTmHo:YAG laser. The IR was tunable from 4.7 to 7.8 μm via crystal angle tuning. A maximum optical to optical efficiency of 56% was obtained from the pump (2.09 μm)

  7. High energy picosecond Yb:YAG CPA system at 10 Hz repetition rate for pumping optical parametric amplifiers.

    Science.gov (United States)

    Klingebiel, Sandro; Wandt, Christoph; Skrobol, Christoph; Ahmad, Izhar; Trushin, Sergei A; Major, Zsuzsanna; Krausz, Ferenc; Karsch, Stefan

    2011-03-14

    We present a chirped pulse amplification (CPA) system based on diode-pumped Yb:YAG. The stretched ns-pulses are amplified and have been compressed to less than 900 fs with an energy of 200 mJ and a repetition rate of 10 Hz. This system is optically synchronized with a broadband seed laser and therefore ideally suited for pumping optical parametric chirped pulse amplification (OPCPA) stages on a ps-timescale.

  8. Numerical modelling of the pump-to-signal relative intensity noise transfer in two-pump fibre optical parametric amplifiers

    Indian Academy of Sciences (India)

    H Pakarzadeh; A Zakery

    2011-10-01

    An accurate numerical model to investigate the pump-to-signal relative intensity noise (RIN) transfer in two-pump fibre optical parametric amplifiers (2-P FOPAs) for low modulation frequencies is presented. Compared to other models in the field, this model takes into account the fibre loss, pump depletion as well as the gain saturation. As a result, the model allows to include a wide range of practical circumstances, both in and beyond the undepleted pump regime, related to different applications of FOPAs. In the small-signal or undepleted pump regime, the model predicts the ripples of the RIN spectrum very well and yields better results than those of other models. It is shown that beyond the small-signal regime, pump power variations do not remain unchanged over the length of the amplifier and for high signal powers, when the FOPA saturates, minimum pump-to-signal RIN transfer occurs. The results of the model are also compared with the available experimental data in the field and a very good agreement can be seen.

  9. Characteristics and performance of an intensity-modulated optically pumped magnetometer in comparison to the classical M(x) magnetometer.

    Science.gov (United States)

    Schultze, Volkmar; Ijsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Meyer, Hans-Georg

    2012-06-18

    We compare the performance of two methods for the synchronization of the atomic spins in optically pumped magnetometers: intensity modulation of the pump light and the classical M(x) method using B(1) field modulation. Both techniques use the same set-up and measure the resulting features of the light after passing a micro-fabricated Cs cell. The intensity-modulated pumping shows several advantages: better noise-limited magnetic field sensitivity, misalignment between pumping and spin synchronization is excluded, and magnetometer arrays without any cross-talk can be easily set up.

  10. Precision measurement of the nuclear polarization in laser-cooled, optically pumped $^{37}\\mathrm{K}$

    CERN Document Server

    Fenker, Benjamin; Melconian, Dan; Anderson, Rhys M A; Anholm, Melissa; Ashery, Daniel; Behling, Richard S; Cohen, Iuliana; Craiciu, Ioana; Donohue, John M; Farfan, Christian; Friesen, Daniel; Gorelov, Alexandre; McNeil, James; Mehlman, Michael; Norton, Heather; Olchanski, Konstantin; Smale, Scott; Theriault, O; Vantyghem, Adrian N; Warner, Claire L

    2016-01-01

    We report a measurement of the nuclear polarization of laser-cooled, optically-pumped $^{37}\\mathrm{K}$ atoms which will allow us to precisely measure angular correlation parameters in the beta-decay of the same atoms. These results will be used to test the $V-A$ framework of the weak interaction at high precision. At the TRIUMF Neutral Atom Trap (TRINAT), a magneto-optical trap (MOT) confines and cools neutral $^{37}\\mathrm{K}$ atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of $P = 0.9913\\pm0.0008$, which is significantly more precise than previous measurements with this technique. Since our current measurement of the beta-asymmetry has $0.2\\%$ statistical uncertainty, the polarization measurement reported here will not limit its over...

  11. Optically pumped planar waveguide lasers: Part II: Gain media, laser systems, and applications

    Science.gov (United States)

    Grivas, Christos

    2016-01-01

    The field of optically pumped planar waveguide lasers has seen a rapid development over the last two decades driven by the requirements of a range of applications. This sustained research effort has led to the demonstration of a large variety of miniature highly efficient laser sources by combining different gain media and resonator geometries. One of the most attractive features of waveguide lasers is the broad range of regimes that they can operate, spanning from continuous wave and single frequency through to the generation of femtosecond pulses. Furthermore, their technology has experienced considerable advances to provide increased output power levels, deriving benefits from the relative immunity from the heat generated in the gain medium during laser operation and the use of cladding-pumped architectures. This second part of the review on optically pumped planar waveguide lasers provides a snapshot of the state-of-the-art research in this field in terms of gain materials, laser system designs, and as well as a perspective on the status of their application as real devices in various research areas.

  12. Velocity anisotropy effect in pump-probe spectra of cesium in a micrometric thickness optical cell

    Science.gov (United States)

    Ghosh, P. N.; Mitra, S.; Ray, B.; Krasteva, A.; Slavov, D.; Todorov, P.; Cartaleva, S.

    2015-01-01

    The pump-probe spectra in a cell of micrometric thickness containing cesium vapor are reported. The line shape and nonlinear features observed in the case of fluorescence in the direction parallel to the cell windows and the transmission spectra observed along the propagation direction of the probe beam show considerable differences in the spectral profiles. We observed Electromagnetically Induced Transparency (EIT) and enhanced Velocity Selective Optical Pumping (VSOP) signals. Atoms moving nearly parallel to the windows and perpendicular to the collinear pump and probe beams will see much lower Doppler shift of incident frequencies and hence will lead to considerable narrowing of the Doppler background in the fluorescence spectra. The coherence decay rate is also low for such atoms as they do not meet with the cell walls. A theoretical model based on five level optical Bloch equations is used to simulate the spectra. The Doppler convolution includes all possible orientation of atomic velocities with respect to the laser beam direction. The simulated curves reproduce the observed sharp EIT peaks and enhanced broad VSOP signals for the closed probe transition in the fluorescence and absorption spectra. The observed effect of the light intensity and temperature change on the non-linear features is reproduced by the simulation.

  13. Continuous-wave optically pumped green perovskite vertical-cavity surface-emitter

    KAUST Repository

    Alias, Mohd Sharizal

    2017-09-11

    We report an optically pumped green perovskite vertical-cavity surface-emitter operating in continuous-wave (CW) with a power density threshold of ∼89  kW/cm2. The device has an active region of CH3NH3PbBr3 embedded in a dielectric microcavity; this feat was achieved with a combination of optimal spectral alignment of the optical cavity modes with the perovskite optical gain, an adequate -factor of the microcavity, adequate thermal stability, and improved material quality with a smooth, passivated, and annealed thin active layer. Our results signify a way towards efficient CW perovskite emitter operation and electrical injection using low-cost fabrication methods for addressing monolithic optoelectronic integration and lasing in the green gap.

  14. Continuous-wave optically pumped green perovskite vertical-cavity surface-emitter

    KAUST Repository

    Alias, Mohd Sharizal

    2017-09-11

    We report an optically pumped green perovskite vertical-cavity surface-emitter operating in continuous-wave (CW) with a power density threshold of ~89 kW/cm. The device has an active region of CHNHPbBr embedded in a dielectric microcavity; this feat was achieved with a combination of optimal spectral alignment of the optical cavity modes with the perovskite optical gain, an adequate Q-factor of the microcavity, adequate thermal stability, and improved material quality with a smooth, passivated, and annealed thin active layer. Our results signify a way towards efficient CW perovskite emitter operation and electrical injection using low-cost fabrication methods for addressing monolithic optoelectronic integration and lasing in the green gap.

  15. Synchronously pumped CdSe optical parametric oscillator in the 9-10 microm region.

    Science.gov (United States)

    Watson, M A; O'Connor, M V; Shepherd, D P; Hanna, D C

    2003-10-15

    Continuous mode-locked operation of a singly resonant, synchronously pumped optical parametric oscillator (SPOPO) based on CdSe has produced idler output tuned over the range of 9.1-9.7 microm, the longest wavelength generated so far to our knowledge from a SPOPO. Average idler powers as high as approximately 70 mW are generated in the crystal. Tandem pumping with a diffraction-grating-tuned parametric oscillator in periodically poled lithium niobate provides a convenient and agile means of tuning the noncritically phase-matched CdSe device. The absence of any detrimental thermal effects in the CdSe crystal suggests that significant further power scaling should be possible, with idler tuning ranges extendable to cover 8-12 microm.

  16. Dye linked conjugated homopolymers: using conjugated polymer electroluminescence to optically pump porphyrin-dye emission

    DEFF Research Database (Denmark)

    Nielsen, K.T.; Spanggaard, H.; Krebs, Frederik C

    2004-01-01

    . Electroluminescent devices of the homopolymer itself and of the zinc-porphyrin containing polymer were prepared and the nature of the electroluminescence was characterized. The homopolymer segments were found to optically pump the emission of the zinc-porphyrin dye moities. The homopolymer exhibits blue......Zinc-porphyrin dye molecules were incorporated into the backbone of a conjugated polymer material by a method, which allowed for the incorporation of only one zinc-porphyrin dye molecule into the backbone of each conjugated polymer molecule. The electronic properties of the homopolymer were......-green emission and the zinc-porphyrin linked homopolymers emit near-infrared/infrared light. This was demonstrated to be due to electroluminescence pumping of the zinc-porphyrin moieties that were covalently linked to homopolymer material. When only one zinc-porphyrin dye was incorporated into the backbone...

  17. Optomechanical oscillator pumped and probed by optically two isolated photonic crystal cavity systems.

    Science.gov (United States)

    Tian, Feng; Sumikura, Hisashi; Kuramochi, Eiichi; Taniyama, Hideaki; Takiguchi, Masato; Notomi, Masaya

    2016-11-28

    Optomechanical control of on-chip emitters is an important topic related to integrated all-optical circuits. However, there is neither a realization nor a suitable optomechanical structure for this control. The biggest obstacle is that the emission signal can hardly be distinguished from the pump light because of the several orders' power difference. In this study, we designed and experimentally verified an optomechanical oscillation system, in which a lumped mechanical oscillator connected two optically isolated pairs of coupled one-dimensional photonic crystal cavities. As a functional device, the two pairs of coupled cavities were respectively used as an optomechanical pump for the lumped oscillator (cavity pair II, wavelengths were designed to be within a 1.5 μm band) and a modulation target of the lumped oscillator (cavity pair I, wavelengths were designed to be within a 1.2 μm band). By conducting finite element method simulations, we found that the lumped-oscillator-supported configurations of both cavity pairs enhance the optomechanical interactions, especially for higher order optical modes, compared with their respective conventional side-clamped configurations. Besides the desired first-order in-plane antiphase mechanical mode, other mechanical modes of the lumped oscillator were investigated and found to possibly have optomechanical applications with a versatile degree of freedom. In experiments, the oscillator's RF spectra were probed using both cavity pairs I and II, and the results matched those of the simulations. Dynamic detuning of the optical spectrum of cavity pair I was then implemented with a pumped lumped oscillator. This was the first demonstration of an optomechanical lumped oscillator connecting two optically isolated pairs of coupled cavities, whose biggest advantage is that one cavity pair can be modulated with an lumped oscillator without interference from the pump light in the other cavity pair. Thus, the oscillator is a suitable

  18. Flexible and scalable wavelength multicast of coherent optical OFDM with tolerance against pump phase-noise using reconfigurable coherent multi-carrier pumping.

    Science.gov (United States)

    Lu, Guo-Wei; Bo, Tianwai; Sakamoto, Takahide; Yamamoto, Naokatsu; Chan, Calvin Chun-Kit

    2016-10-03

    Recently the ever-growing demand for dynamic and high-capacity services in optical networks has resulted in new challenges that require improved network agility and flexibility in order for network resources to become more "consumable" and dynamic, or elastic, in response to requests from higher network layers. Flexible and scalable wavelength conversion or multicast is one of the most important technologies needed for developing agility in the physical layer. This paper will investigate how, using a reconfigurable coherent multi-carrier as a pump, the multicast scalability and the flexibility in wavelength allocation of the converted signals can be effectively improved. Moreover, the coherence in the multiple carriers prevents the phase noise transformation from the local pump to the converted signals, which is imperative for the phase-noise-sensitive multi-level single- or multi-carrier modulated signal. To verify the feasibility of the proposed scheme, we experimentally demonstrate the wavelength multicast of coherent optical orthogonal frequency division multiplexing (CO-OFDM) signals using a reconfigurable coherent multi-carrier pump, showing flexibility in wavelength allocation, scalability in multicast, and tolerance against pump phase noise. Less than 0.5 dB and 1.8 dB power penalties at a bit-error rate (BER) of 10-3 are obtained for the converted CO-OFDM-quadrature phase-shift keying (QPSK) and CO-OFDM-16-ary quadrature amplitude modulation (16QAM) signals, respectively, even when using a distributed feedback laser (DFB) as a pump source. In contrast, with a free-running pumping scheme, the phase noise from DFB pumps severely deteriorates the CO-OFDM signals, resulting in a visible error-floor at a BER of 10-2 in the converted CO-OFDM-16QAM signals.

  19. High-performance genetically targetable optical neural silencing by light-driven proton pumps.

    Science.gov (United States)

    Chow, Brian Y; Han, Xue; Dobry, Allison S; Qian, Xiaofeng; Chuong, Amy S; Li, Mingjie; Henninger, Michael A; Belfort, Gabriel M; Lin, Yingxi; Monahan, Patrick E; Boyden, Edward S

    2010-01-07

    The ability to silence the activity of genetically specified neurons in a temporally precise fashion would provide the opportunity to investigate the causal role of specific cell classes in neural computations, behaviours and pathologies. Here we show that members of the class of light-driven outward proton pumps can mediate powerful, safe, multiple-colour silencing of neural activity. The gene archaerhodopsin-3 (Arch) from Halorubrum sodomense enables near-100% silencing of neurons in the awake brain when virally expressed in the mouse cortex and illuminated with yellow light. Arch mediates currents of several hundred picoamps at low light powers, and supports neural silencing currents approaching 900 pA at light powers easily achievable in vivo. Furthermore, Arch spontaneously recovers from light-dependent inactivation, unlike light-driven chloride pumps that enter long-lasting inactive states in response to light. These properties of Arch are appropriate to mediate the optical silencing of significant brain volumes over behaviourally relevant timescales. Arch function in neurons is well tolerated because pH excursions created by Arch illumination are minimized by self-limiting mechanisms to levels comparable to those mediated by channelrhodopsins or natural spike firing. To highlight how proton pump ecological and genomic diversity may support new innovation, we show that the blue-green light-drivable proton pump from the fungus Leptosphaeria maculans (Mac) can, when expressed in neurons, enable neural silencing by blue light, thus enabling alongside other developed reagents the potential for independent silencing of two neural populations by blue versus red light. Light-driven proton pumps thus represent a high-performance and extremely versatile class of 'optogenetic' voltage and ion modulator, which will broadly enable new neuroscientific, biological, neurological and psychiatric investigations.

  20. Efficient, high-power, ytterbium-fiber-laser-pumped picosecond optical parametric oscillator.

    Science.gov (United States)

    Kokabee, O; Esteban-Martin, A; Ebrahim-Zadeh, M

    2010-10-01

    We report a high-power picosecond optical parametric oscillator (OPO) synchronously pumped by a Yb fiber laser at 1.064 μm, providing 11.7 W of total average power in the near to mid-IR at 73% extraction efficiency. The OPO, based on a 50 mm MgO:PPLN crystal, is pumped by 20.8 ps pulses at 81.1 MHz and can simultaneously deliver 7.1 W of signal at 1.56 μm and 4.6 W of idler at 3.33 μm for 16 W of pump power. The oscillator has a threshold of 740 mW, with maximum signal power of 7.4 W at 1.47 μm and idler power of 4.9 W at 3.08 μm at slope efficiencies of 51% and 31%, respectively. Wavelength coverage across 1.43-1.63 μm (signal) and 4.16-3.06 μm (idler) is obtained, with a total power of ~11 W and an extraction efficiency of ~68%, with pump depletion of ~78% maintained over most of the tuning range. The signal and idler output have a single-mode spatial profile and a peak-to-peak power stability of ±1.8% and ±2.9% over 1 h at the highest power, respectively. A signal pulse duration of 17.3 ps with a clean single-peak spectrum results in a time-bandwidth product of ~1.72, more than four times below the input pump pulses.

  1. RESEARCH OF THERMO-OPTICAL INHOMOGENEITIES IN Yb-Er GLASS AT DIODE PUMPING

    Directory of Open Access Journals (Sweden)

    V. Khramov

    2016-03-01

    Full Text Available Subject of Research. Investigation method of thermo-optical distortions in solid-state lasers was developed and presented. The method can be easily used for research of small diameter (approximately 2 mm active elements. Method. The experimental method described in this paper is based on the registration of deviation of the energy center of the probe beam passing through the thermally stressed active element. Main Results. We have presented experimental results of the thermal lens optical power research in the active element made of Yb-Er glass pumped transversely by a laser diode in the following modes: without generating, free-running and Q-switching. We have submitted obtained dependences of the optical power on the pumping energy. The measurements have been performed for the two polarization components at two wavelengths (632.8 nm and 1550 nm showing the absence of explicit astigmatism of the thermal lens. Practical Relevance. Knowledge of the thermal regime of such lasers gives the possibility for more precise calculation of the resonator parameters in terms of the thermal lens occurrence.

  2. A novel electro-optical pump-probe system for bioelectromagnetic investigations

    Science.gov (United States)

    De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe

    2012-10-01

    In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of

  3. Liquid crystal polarimetry for metastability exchange optical pumping of {sup 3}He

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, J.D., E-mail: jdmax@mit.edu; Epstein, C.S.; Milner, R.G.

    2014-11-11

    We detail the design and operation of a compact, discharge light polarimeter for metastability exchange optical pumping of {sup 3}He gas near 1 torr under a low magnetic field. The nuclear polarization of {sup 3}He can be discerned from its electron polarization, measured via the circular polarization of 668 nm discharge light from an RF excitation. This apparatus measures the circular polarization of this very dim discharge light using a nematic liquid crystal wave retarder (LCR) and a high-gain, transimpedance amplified Si photodiode. We outline corrections required in such a measurement and discuss contributions to its systematic error.

  4. Search and Characterization of Optical Ceramics and Crystals for Diode-pumped Laser Oscillations

    Science.gov (United States)

    2013-04-01

    Higher microhardness ; - No cleavage planes; - Large size; Also for some experiments, the optical quality of the resultant ceramic material was...samples to lase was tested in the setup shown in Fig.19. The samples were pumped with a 967 nm fiber coupled (fiber core 120 m) 10 W laser diode with...Because of low levels of heating, testing of the CaF2:Yb 3+ ceramics could be performed in the continuous wave (CW) mode of operation. In Fig.23

  5. Analytical Solutions of Temporal Evolution of Populations in Optically-Pumped Atoms with Circularly Polarized Light

    Directory of Open Access Journals (Sweden)

    Heung-Ryoul Noh

    2016-03-01

    Full Text Available We present an analytical calculation of temporal evolution of populations for optically pumped atoms under the influence of weak, circularly polarized light. The differential equations for the populations of magnetic sublevels in the excited state, derived from rate equations, are expressed in the form of inhomogeneous second-order differential equations with constant coefficients. We present a general method of analytically solving these differential equations, and obtain explicit analytical forms of the populations of the ground state at the lowest order in the saturation parameter. The obtained populations can be used to calculate lineshapes in various laser spectroscopies, considering transit time relaxation.

  6. Spin relaxation time dependence on optical pumping in GaAs:Mn

    Science.gov (United States)

    Burobina, Veronika; Binek, Christian

    2015-03-01

    We analyze the dependence of electron spin relaxation time on optical pumping in a partially-compensated acceptor semiconductor GaAs:Mn using analytic solutions for the kinetic equations of the charge carrier concentrations. Our results are applied to previous experimental data of spin-relaxation time vs. excitation power for magnetic concentrations of approximately 1017cm-3. The agreement of our analytic solutions with the experimental data supports the mechanism of the earlier-reported atypically long electron-spin relaxation time in the magnetic semiconductor.

  7. Spin relaxation time dependence on optical pumping intensity in GaAs:Mn

    Energy Technology Data Exchange (ETDEWEB)

    Burobina, V. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah 84112-0830 (United States); Binek, Ch. [Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, Theodore Jorgensen Hall, 855 North 16th Street, University of Nebraska, P.O. Box 880299, Lincoln, Nebraska 68588-0299 (United States)

    2014-04-28

    We analyze the dependence of electron spin relaxation time on optical pumping intensity in a partially compensated acceptor semiconductor GaAs:Mn using analytic solutions for the kinetic equations of the charge carrier concentrations. Our results are applied to previous experimental data of spin-relaxation time vs. excitation power for magnetic concentrations of approximately 10{sup 17} cm{sup −3}. The agreement of our analytic solutions with the experimental data supports the mechanism of the earlier-reported atypically long electron-spin relaxation time in the magnetic semiconductor.

  8. Spin relaxation time dependence on optical pumping intensity in GaAs:Mn

    Science.gov (United States)

    Burobina, V.; Binek, Ch.

    2014-04-01

    We analyze the dependence of electron spin relaxation time on optical pumping intensity in a partially compensated acceptor semiconductor GaAs:Mn using analytic solutions for the kinetic equations of the charge carrier concentrations. Our results are applied to previous experimental data of spin-relaxation time vs. excitation power for magnetic concentrations of approximately 1017 cm-3. The agreement of our analytic solutions with the experimental data supports the mechanism of the earlier-reported atypically long electron-spin relaxation time in the magnetic semiconductor.

  9. Integrated Optical Pumping of Cr & Ti-Doped Sapphire Substrates With III-V Nitride Materials

    Science.gov (United States)

    2005-08-24

    the Cr in sapphire could also permit the construction of white light LEDs . Ultimately, an integrated III-V Nitride optical pump for Ti:Sapphire could...substrates by MOCVD. 2. Characterization of doped sapphire/ InGaN structures byPL to simulate electrical injection by laser or LED device structures Part 2 1...Cr:sapphire substrate. Solid line is the spectrum of blue and red light emitted by InGaN LED epitaxially grown on Cr:sapphire substrate. The light was collected

  10. A CrTmHo:YAG laser pumped ZnGeP2 optical parametric oscillator for mid-infrared spectroscopy

    NARCIS (Netherlands)

    Nieuwenhuis, Ab F.; Lee, Chris J.; Slot, van der Peter J.M.; Lindsay, Ian D.; Gross, Petra; Boller, K.-J.; Powers, Peter E.

    2008-01-01

    We report a singly resonant optical parametric oscillator (SRO) based on a ZnGeP2 crystal directly-pumped by a lamp-pumped Q-switched CrTmHo:YAG laser. The IR wavelength was tuneable from 4.7 μm to 7.8 μm via crystal angle tuning. A maximum optical to optical efficiency of 56% was obtained from pump

  11. A CrTmHo:YAG laser pumped ZnGeP2 optical parametric oscillator for mid-infrared spectroscopy

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; van der Slot, Petrus J.M.; Lee, Christopher James; Lindsay, I.D.; Gross, P.; Boller, Klaus J.; Powers, Peter E.

    2008-01-01

    We report a singly resonant optical parametric oscillator (SRO) based on a ZnGeP2 crystal directly-pumped by a lamp-pumped Q-switched CrTmHo:YAG laser. The IR wavelength was tuneable from 4.7 μm to 7.8 μm via crystal angle tuning. A maximum optical to optical efficiency of 56% was obtained from pump

  12. Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

    Directory of Open Access Journals (Sweden)

    A. Pagies

    2016-06-01

    Full Text Available We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia in gas state. The low-power (<60 mW laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

  13. Fiber-based modulated optical reflectance configuration allowing for offset pump and probe beams

    Science.gov (United States)

    Fleming, A.; Folsom, C.; Jensen, C.; Ban, H.

    2016-12-01

    A new fiber-based modulated optical reflectance configuration is developed in this work. The technique maintains the fiber-based heating laser (pump) and detection laser (probe) in close proximity at a fixed separation distance in a ceramic ferrule. The pump beam periodically heats the sample inducing thermal waves into the sample. The probe beam measures the temperature response at a known distance from the pump beam over a range of heating modulation frequencies. The thermal diffusivity of the sample may be calculated from the phase response between the input heat flux and the temperature response of a sample having a reflective surface. The unique measurement configuration is ideal for in situ measurements and has many advantages for laboratory-based systems. The design and development of the system are reported along with theoretical justification for the experimental design. The thermal diffusivities of Ge and SiC are measured and found to be within 10% of reported literature values. The diffusivity for SiO2 is measured with a relative difference of approximately 100% from the literature value when the ferrule is in contact with the sample. An additional measurement was made on the SiO2 sample with the ferrule not in contact resulting in a difference of less than 2% from the literature value. The difference in the SiO2 measurement when the ferrule is in contact with the sample is likely due to a parallel heat transfer path through the dual-fiber ferrule assembly.

  14. Optical pumping effect in absorption imaging of F =1 atomic gases

    Science.gov (United States)

    Kim, Sooshin; Seo, Sang Won; Noh, Heung-Ryoul; Shin, Y.

    2016-08-01

    We report our study of the optical pumping effect in absorption imaging of 23Na atoms in the F =1 hyperfine spin states. Solving a set of rate equations for the spin populations in the presence of a probe beam, we obtain an analytic expression for the optical signal of the F =1 absorption imaging. Furthermore, we verify the result by measuring the absorption spectra of 23Na Bose-Einstein condensates prepared in various spin states with different probe-beam pulse durations. The analytic result can be used in the quantitative analysis of F =1 spinor condensate imaging and readily applied to other alkali-metal atoms with I =3 /2 nuclear spin such as 87Rb.

  15. Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, G.; Nagai, M., E-mail: mnagai@mp.es.osaka-u.ac.jp, E-mail: ashida@mp.es.osaka-u.ac.jp; Ashida, M., E-mail: mnagai@mp.es.osaka-u.ac.jp, E-mail: ashida@mp.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Matsubara, E. [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Department of Physics, Osaka Dental University, Hirakata, Osaka 573-1121 (Japan); Kanemitsu, Y. [Institute for Chemical Research, Kyoto University, Kyoto 611-0011 (Japan)

    2014-12-08

    We estimated the carrier multiplication efficiency in the most common solar-cell material, Si, by using optical-pump/terahertz-probe spectroscopy. Through close analysis of time-resolved data, we extracted the exact number of photoexcited carriers from the sheet carrier density 10 ps after photoexcitation, excluding the influences of spatial diffusion and surface recombination in the time domain. For incident photon energies greater than 4.0 eV, we observed enhanced internal quantum efficiency due to carrier multiplication. The evaluated value of internal quantum efficiency agrees well with the results of photocurrent measurements. This optical method allows us to estimate the carrier multiplication and surface recombination of carriers quantitatively, which are crucial for the design of the solar cells.

  16. Optically Pumped Atomic Rubidium Lasers: Two-Photon and Exciplex Excitation Mechanisms

    Science.gov (United States)

    Gallagher, Jeffrey E.

    The Doppler-broadened two-photon absorption (TPA) cross-section for the 52S1/2 → 52 D5/2 transition in Rb is measured using direct absorption methods. The selection rule |DeltaF| ≤ 2 applied to both isotopes yields 17 transitions in 3 Doppler limited lines. A detailed model of the intensity profile was also developed to account for a focused Gaussian beam (with an M2 value of 1.09) propagating through a two-photon absorption medium. A peak absorbance of 24% was observed for an intensity of 6.28 kWcm2 at the focus, a Rb density of 4.6x1015 cm-3 , and a path length of 15 cm. Alkali concentrations from 1.61 - 8.52x1015 cm -3 were monitored in the far wing of the D 2 line. Extracting the hyperfine-broadened TPA cross-section from 87 test configurations, while varying the pump power, alkali concentration and focal length, yielded an error-weighted average of 6.75x10^-21 cm4W with a standard deviation of 3.61x10-21 cm4W. This cross-section is sufficient for a pulsed dye laser to bleach the pump transition in the Two-Photon Pumped Alkali Laser (TPAL) that lases at 420 nm and 5.2 microm. Optically pumped atomic rubidium lasers pumped in the blue satellite of the D2 line from the ground Rb-Ar or Rb-Kr collision pair to the dissociative B2S+1/2 state produce laser emission at 780.2 nm. Lasing is achieved for pump wavelengths of 752.3 to greater than 760 nm for the Rb-Ar system and 757.1 -- 760.4 nm for the Rb-Kr system. Slope efficiencies increase with both Rb and Ar concentrations and exceed 0.25% using a heat pipe configuration. The gain is very high with photon build-up times of 1--3.7 ns. Laser induced heating and subsequent condensation of alkali vapor in the heat pipe configuration currently limits operation to less than 2500 Torr.

  17. Stable, continuous-wave, intracavity, optical parametric oscillator pumped by a semiconductor disk laser (VECSEL).

    Science.gov (United States)

    Stothard, D J M; Hopkins, J-M; Burns, D; Dunn, M H

    2009-06-22

    We report relaxation oscillation free, true continuous-wave operation of a singly-resonant, intracavity optical parametric oscillator (OPO) based upon periodically-poled, MgO-doped LiNbO3 and pumped internal to the cavity of a compact, optically-excited semiconductor disk laser (or VECSEL). The very short upper-laser-state lifetime of this laser gain medium, coupled with the enhancing effect of the high-finesse pump laser cavity in which the OPO is located, enables a low threshold, high efficiency intracavity device to be operated free of relaxation oscillations in continuous-wave mode. By optimizing for low-power operation, parametric threshold was achieved at a diode-laser power of only 1.4 W. At 8.5 W of diode-laser power, 205 mW of idler power was extracted, indicating a total down-converted power of 1.25 W, and hence a down-conversion efficiency of 83%.

  18. Generation of <7 fs pulses at 800 nm from a blue-pumped optical parametric amplifier at degeneracy.

    Science.gov (United States)

    Siddiqui, A M; Cirmi, G; Brida, D; Kärtner, F X; Cerullo, G

    2009-11-15

    We generate ultrabroadband pulses at 800 nm from an optical parametric amplifier (OPA) pumped by the second harmonic of a Ti:sapphire system and working at degeneracy. The OPA is seeded by a white-light continuum generated from a near-IR OPA pumped by the same laser. Nearly transform-limited <7 fs pulses, fully characterized in amplitude and phase, are obtained with a chirped mirror compressor. The system fills the gap around 800 nm for broadband continuum seeded OPAs pumped by Ti:sapphire-based sources.

  19. Low Noise Frequency Comb Sources Based on Synchronously Pumped Doubly Resonant Optical Parametric Oscillators

    Science.gov (United States)

    Wan, Chenchen

    Optical frequency combs are coherent light sources consist of thousands of equally spaced frequency lines. Frequency combs have achieved success in applications of metrology, spectroscopy and precise pulse manipulation and control. The most common way to generate frequency combs is based on mode-locked lasers which has the output spectrum of comb structures. To generate stable frequency combs, the output from mode-locked lasers need to be phase stabilized. The whole comb lines will be stabilized if the pulse train repetition rate corresponding to comb spacing and the pulse carrier envelope offset (CEO) frequency are both stabilized. The output from a laser always has fluctuations in parameters known as noise. In laser applications, noise is an important factor to limit the performance and often need to be well controlled. For example in precision measurement such as frequency metrology and precise spectroscopy, low laser intensity and phase noise is required. In mode-locked lasers there are different types of noise like intensity noise, pulse temporal position noise also known as timing jitter, optical phase noise. In term for frequency combs, these noise dynamics is more complex and often related. Understanding the noise behavior is not only of great interest in practical applications but also help understand fundamental laser physics. In this dissertation, the noise of frequency combs and mode-locked lasers will be studied in two projects. First, the CEO frequency phase noise of a synchronously pumped doubly resonant optical parametric oscillators (OPO) will be explored. This is very important for applications of the OPO as a coherent frequency comb source. Another project will focus on the intensity noise coupling in a soliton fiber oscillator, the finding of different noise coupling in soliton pulses and the dispersive waves generated from soliton perturbation can provide very practical guidance for low noise soliton laser design. OPOs are used to generate

  20. Optimization of beam quality and optical-to-optical efficiency of Yb:YAG thin-disk regenerative amplifier by pulsed pumping.

    Science.gov (United States)

    Chyla, Michal; Miura, Taisuke; Smrz, Martin; Jelinkova, Helena; Endo, Akira; Mocek, Tomas

    2014-03-15

    We demonstrate an optimization method of beam quality and optical-to-optical (O-O) efficiency by using pulsed pumping. By changing the pulse duration and the peak intensity of pump pulse at the repetition rate of 1 kHz, the beam quality and O-O efficiency of the Yb:YAG thin-disk regenerative amplifier can be improved. We applied this method to the regenerative amplifier under the pumping wavelength of both 940 and 969 nm, and found that the method was effective in both pumping wavelengths. Although a Yb:YAG thin disk soldered on a copper tungsten heat sink, which has poor thermal properties compared with a thin disk mounted on a diamond substrate, was applied as a gain media, we obtained 45 mJ output with 19.3% O-O efficiency and nearly diffraction-limited beam.

  1. Mid-infrared ZGP optical parametric oscillator directly pumped by a lamp-pumped, Q-switched Cr,Tm,Ho:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Ab F.; Lee, Chris J.; Slot, van der Peter J.M.; Gross, Petra; Boller, Klaus-Jochen; Powers, Peter E.

    2007-01-01

    We generate mid-infrared pulsed light tunable between 5.6 μm and 6.6 μm using an optical parametric oscillator (OPO) directly pumped by a Cr,Tm,Ho:YAG, Q -switched laser operating at 2.1 μm. The Holmium laser uses a RTP Q -switch to produce pulses shorter than 100 ns and energies of up to 42 mJ in a

  2. Mid-Infrared ZGP optical parametric oscillator directly pumped by a lamp-pumped, Q-switched Cr,Tm,Ho:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; van der Slot, Petrus J.M.; Gross, P.; Boller, Klaus J.; Powers, Peter E.

    2007-01-01

    We generate mid-infrared pulsed light tunable between 5.6 μm and 6.6 μm using an optical parametric oscillator (OPO) directly pumped by a Cr,Tm,Ho:YAG, Q -switched laser operating at 2.1 μm. The Holmium laser uses a RTP Q -switch to produce pulses shorter than 100 ns and energies of up to 42 mJ in a

  3. Optically initialized robust valley-polarized holes in monolayer WSe2

    KAUST Repository

    Hsu, Wei-Ting

    2015-11-25

    A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (~10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

  4. Suppression of WDM four-wave mixing crosstalk in fibre optic parametric amplifier using Raman-assisted pumping.

    Science.gov (United States)

    Redyuk, A; Stephens, M F C; Doran, N J

    2015-10-19

    We perform an extensive numerical analysis of Raman-Assisted Fibre Optical Parametric Amplifiers (RA-FOPA) in the context of WDM QPSK signal amplification. A detailed comparison of the conventional FOPA and RA-FOPA is reported and the important advantages offered by the Raman pumping are clarified. We assess the impact of pump power ratios, channel count, and highly nonlinear fibre (HNLF) length on crosstalk levels at different amplifier gains. We show that for a fixed 200 m HNLF length, maximum crosstalk can be reduced by up to 7 dB when amplifying 10x58Gb/s QPSK signals at 20 dB net-gain using a Raman pump of 37 dBm and parametric pump of 28.5 dBm in comparison to a standard single-pump FOPA using 33.4 dBm pump power. It is shown that a significant reduction in four-wave mixing crosstalk is also obtained by reducing the highly nonlinear fibre interaction length. The trend is shown to be generally valid for different net-gain conditions and channel grid size. Crosstalk levels are additionally shown to strongly depend on the Raman/parametric pump power ratio, with a reduction in crosstalk seen for increased Raman pump power contribution.

  5. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    Science.gov (United States)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  6. Production of Hyperpolarized 129Xe Gas Without Nitrogen by Optical Pumping at 133Cs D2 line in Flow System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xin; SUN Xian-Ping; LUO Jun; ZENG Xi-Zhi; LIU Mai-Li; ZHAN Ming-Sheng

    2004-01-01

    @@ We report production of hyperpolarized 129Xe gas via spin-exchange with optically pumped Cs atoms at the D2 line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized 129Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized 129Xe gas has also been observed in the flow system.

  7. 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.

  8. 888 nm pumped dual Nd:YVO4 crystals acousto-optic Q-switched laser

    Science.gov (United States)

    Zhang, Wenqi; Shen, Yijie; Meng, Yuan; Gong, Mali

    2017-10-01

    888 nm pumped acousto-optic (AO) Q-switched laser with high output power and high efficiency under dual Nd:YVO4 crystals configuration is firstly demonstrated and rate equations for dual-crystal lasers are further ameliorated and investigated. In continuous wave (CW) operation, we experimentally achieve a maximum output power exceeding 50 W. The global optical efficiency reaches 49.5% and the slope efficiency attains 55.5% via using a 1.5 at.% crystal with a 0.5 at.% crystal. In Q-switch operation, by utilizing double 0.5 at.% crystals, the global optical efficiency rises from 25.6% to 45.6% and the pulse duration varies from 26.2 to 42.4 ns when pulse repetition frequency (PRF) increases from 10 to 100 kHz. The measured beam quality factors M2 at 100 kHz are 1.012 and 1.041 with 52.8 W output power in the two orthogonal directions respectively.

  9. Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near-infrared light.

    Science.gov (United States)

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

    2014-09-01

    Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near-infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750 nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200 s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750 nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780 rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump.

  10. Optimally efficient, high power, Yb:fiber laser pumped, near- to mid-infrared picosecond optical parametric oscillator

    CERN Document Server

    Kokabee, Omid

    2014-01-01

    Absolute output power optimization and performance of a near- to mid-infrared picosecond optical parametric oscillator (OPO) is studied at two high pump powers using a widely-tunable output coupling (OC) technique which provides 15% to 68% OC. The MgO:PPLN-based OPO is synchronously pumped at 81.1 MHz by an Yb:fiber laser with double-peak spectrum. At 2 W pump power, maximum signal (at 1.46 $\\mu$m) and idler (at 3.92 $\\mu$m) power of 670 mW and 270 mW are obtained at 27% OC at 47% total extraction efficiency and 58% pump power depletion where at 15.5 W pump power, 7.4 W signal and 2.7 W idler power are extracted at 53% OC at 65% total extraction efficiency and 80% pump depletion. With respect to non-optimum points, OPO provides signal pulses with narrower single-peak spectrum, smaller time-bandwidth product, much better circular single-mode TEM00 spatial profile and passive peak-to-peak power stability of $\\pm$4.6% at 2 W and $\\pm$1% at 15.5 W pump power in optimum power extraction points.

  11. Collinear laser spectroscopy of manganese isotopes using optical pumping in ISCOOL

    CERN Multimedia

    Marsh, B A; Neyens, G; Flanagan, K; Rajabali, M M; Reponen, M; Campbell, P; Procter, T J

    Recently, optical pumping of ions has been achieved inside an ion beam cooler-buncher. By illuminating the central axis of the cooler with laser light, subsequent decay populates selected ionic metastable states. This population enhancement is retained as the ion beam is delivered to an experimental station. In the case of collinear laser spectroscopy, transitions can then be excited from a preferred metastable level, rather than the ground-state. This proposal seeks to establish and develop the technique for ISCOOL. As a test of efficiency, this will be applied to the study of $^{55-66}$Mn isotopes using collinear laser spectroscopy-expanding an earlier study where the benefit of the technique was demonstrated. This will provide nuclear spins, magnetic-dipole and electric-quadrupole moments and changes in mean-square charge radii across N = 40 shell closure candidate and into a region where an onset of deformation, and a new "island of inversion" is predicted.

  12. Resonators induced transparency and optical switching assisted by optofluidic pump system

    Science.gov (United States)

    Chen, Fang; Sun, Li-Hui

    2016-12-01

    A tunable plasmonic induced transparency (PIT)-based light switching is proposed and investigated. The proposed structure consists of a bus waveguide, two nanoresonators and an optofluidic pump system for actively tuning the system’s transmission. By using the finite difference time domain method, it is found that the interferences between the dark and bright mode resonators can be controlled by manipulating the fluid filled in the resonator, leading to an actively tunable plasmonic switch, the transmittance can be flexibly tuned from near unity to zero. The structure in our paper has the following advantages, such as ultracompact size and easy fabrication. Our study will provide a possibility for designing the ultrafast devices in highly integrated optical circuits.

  13. Self-cavity lasing in optically pumped single crystals of p-sexiphenyl

    Directory of Open Access Journals (Sweden)

    Hisao Yanagi

    2016-08-01

    Full Text Available Organic single-crystal self-cavities are prepared by solution growth of p-sexiphenyl (p-6P. Based on Fabry-Pérot feedback inside a quasi-lozenge-shaped platelet crystal, edge-emitting laser is obtained under optical pumping. The multimode lasing band appears at the 0-1 or 0-2 vibronic progressions depending on the excitation conditions which affect the self-absorption effect. Cavity-size dependence of amplified spontaneous emission (ASE is investigated with laser-etched single crystals of p-6P. As the cavity length of square-shaped crystal is reduced from 100 to 10 μm, ASE threshold fluence is decreased probably due to size-dependent light confinement in the crystal cavity.

  14. Topological phase transition and charge pumping in a one-dimensional periodically driven optical lattice

    Science.gov (United States)

    Xu, Zhihao; Zhang, Yunbo; Chen, Shu

    2017-07-01

    Experimental realizations of topological quantum systems and detections of topological invariants in ultracold atomic systems have been a greatly attractive topic. In this work, we propose a scheme to realize topologically different phases in a bichromatic optical lattice subjected to a periodically driven tilt harmonic oscillation, which can be effectively described by a superlattice model with tunable long-range hopping processes. By tuning the ratio of nearest-neighbor (NN) and next-nearest-neighbor (NNN) hopping amplitudes, the system undergoes a topological phase transition accompanied by the change of topological numbers of the lowest band from -1 to 2. Using a slowly time-periodic modulation, the system emerges distinct quantized topological pumped charges (TPCs) of atoms in the filled band for different topological phases. Our scheme is realizable in current cold atomic technique.

  15. Nuclear spin polarized H and D by means of spin-exchange optical pumping

    Science.gov (United States)

    Stenger, Jörn; Grosshauser, Carsten; Kilian, Wolfgang; Nagengast, Wolfgang; Ranzenberger, Bernd; Rith, Klaus; Schmidt, Frank

    1998-01-01

    Optically pumped spin-exchange sources for polarized hydrogen and deuterium atoms have been demonstrated to yield high atomic flow and high electron spin polarization. For maximum nuclear polarization the source has to be operated in spin temperature equilibrium, which has already been demonstrated for hydrogen. In spin temperature equilibrium the nuclear spin polarization PI equals the electron spin polarization PS for hydrogen and is even larger than PS for deuterium. We discuss the general properties of spin temperature equilibrium for a sample of deuterium atoms. One result are the equations PI=4PS/(3+PS2) and Pzz=PSṡPI, where Pzz is the nuclear tensor polarization. Furthermore we demonstrate that the deuterium atoms from our source are in spin temperature equilibrium within the experimental accuracy.

  16. Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Coffer, J.; Encalada, N.; Huang, M.; Camparo, J. [Physical Sciences Laboratories, The Aerospace Corporation 2310, E. El Segundo Blvd., El Segundo, California 90245 (United States)

    2014-10-28

    We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

  17. Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

    OpenAIRE

    Kosch, M. J.; Pedersen, T; Hughes, J; Marshall, R.; Gerken, E.; A. Senior; Sentman, D.; McCarrick, M.; Djuth, F. T.

    2005-01-01

    International audience; High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The Hig...

  18. Two-Level Dipolar System in a Heat Bath: High-Pump Power Effects in the Nonlinear Optical Responses

    Science.gov (United States)

    Paz, J. L.; León-Torres, J. R.; Lascano, Luis; Alvarado, Ysaias J.; Costa-Vera, Cesar

    2017-06-01

    Using the four-wave mixing spectroscopy, we analyze the nonlinear optical properties in a strongly driven two-level system, using a perturbative treatment where, the pump field is considered at all orders, second order in the probe, and first order for the signal field, when the stochastic effects of the solvent are considered. Significant variations in the nonlinear optical properties due mainly to changes in the probe intensity, chemical concentrations, and transversal relaxation times are observed.

  19. Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

    OpenAIRE

    M. J. Kosch; Pedersen, T; Hughes, J; Marshall, R; Gerken, E.; Senior, A.; Sentman, D.; McCarrick, M.; Djuth, F. T.

    2005-01-01

    International audience; High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The Hig...

  20. Characteristics of stimulated emission from optically pumped freestanding GaN grown by hydride vapor-phase epitaxy

    CERN Document Server

    Lee, M H; Kim, S T; Chung, S H; Moon, D C

    1999-01-01

    In this study, we observed optically pumped stimulated emission at room temperature in quasi-bulk GaN prepared from thick-film GaN grown on a sapphire substrate by using hydride vapor-phase epitaxy and subsequent mechanical removal of the sapphire substrate. The stimulated emission from the surface and 1-mm-wide-cleaved cavity of the GaN was red-shifted compared to the spontaneous emission by increasing the optical pumping-power density, and the full width at half maximum (FWHM) of the peak decreased. The stimulated emission was demonstrated to have a highly TE-mode polarized nature, and the super-linear dependence of the integrated emission intensity on the excitation power indicated a threshold pump-power density of I sub t sub h = 2 MW/cm sup 2 for one set of stimulated emissions.

  1. Demonstration of Cascaded In-Line Single-Pump Fiber Optical Parametric Amplifiers in Recirculating Loop Transmission

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Ozolins, Oskars; An, Yi

    2012-01-01

    The performance of cascaded single-pump fiber optical parametric amplifiers (FOPAs) is experimentally studied for the first time using recirculating loop transmission with 80-km dispersion managed spans. Error-free performance has been achieved over 320 km for 40-Gbit/s CSRZ-OOK and CSRZ...

  2. Rotationally relaxed, grating tuned laser oscillations in optically pumped C/sub 2/D/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, T.A.; Wittig, C.

    1982-07-15

    Rotationally relaxed, grating tuned laser oscillations are obtained in the frequency range 500--562 cm/sup -1/ via the optical pumping of C/sub 2/D/sub 2//He mixtures with a transverse, electric, atmospheric (TEA) CO/sub 2/ laser. Strong Q-branch oscillations at 530.8 cm/sup -1/ are also reported.

  3. Laser action at 16. mu. by optical pumping of CO/sub 2/ with an HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Stepanov, B.I.; Trushin, S.A.; Churakov, V.V.

    1977-08-01

    Calculations are presented on the threshold properties of a CO/sub 2/ laser that is optically pumped by the P/sub 1/(7) line of a HF laser. The dependence on the CO/sub 2/ pressure is considered.(AIP)

  4. Light-shift suppression in a miniaturized Mx optically pumped Cs magnetometer array with enhanced resonance signal using off-resonant laser pumping.

    Science.gov (United States)

    Scholtes, Theo; Schultze, Volkmar; IJsselsteijn, Rob; Woetzel, Stefan; Meyer, Hans-Georg

    2012-12-31

    The performance of an optically pumped Mx magnetometer with miniaturized Cs cell at earth's magnetic field strength (50 μT) is investigated. Operation using detuned high intensity laser light is shown to be superior to the conventional resonant operation in terms of the projected shot-noise-limited ( 50 fT/√Hz) and the actual noise-limited sensitivity using a noise compensation method. The Zeeman light shift effect, emerging due to the off-resonant circularly polarized laser radiation and leading to a strong orientational dependence of the measurement, is suppressed by averaging two identical magnetometer configurations pumped with oppositely circularly polarized light. A residual heading error within the range of 14 nT, limited by the present experimental characterization setup, was achieved.

  5. Double resonance fequency light shift compensation in optically oriented laser-pumped alkali atoms

    Energy Technology Data Exchange (ETDEWEB)

    Baranov, A. A., E-mail: lexusbar@gmail.com; Ermak, S. V.; Sagitov, E. A.; Smolin, R. V.; Semenov, V. V. [St. Petersburg Polytechnic University (Russian Federation)

    2015-09-15

    The contributions of the vector and scalar components to the magnetically dependent microwave transition frequency light shift are analyzed and the compensation of these components is experimentally demonstrated for the {sup 87}Rb atoms optically oriented by a laser tuned to the D{sub 2} line of the head doublet. The Allan variance is studied as a function of the averaging time for a tandem of optically pumped quantum magnetometers (OPQMs), one of which is based on a low-frequency spin oscillator while another is based on a quantum microwave discriminator with a resonance frequency that corresponds to magnetically dependent transitions between HFS sublevels with the extremal value of the magnetic quantum number. It is shown that the compensation of the scalar and vector components of the light shift in OPQMs reduces the Allan variance at averaging times that exceed hundreds of seconds compared to a quantum discriminator based on the magnetically independent 0–0 transition. In this case, the minimal Allan variance in OPQMs at the end resonance is achieved at considerably longer averaging times than in the case of the quantum discriminator that is tuned to the 0–0 transition frequency.

  6. Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump

    Science.gov (United States)

    Pennetta, Riccardo; Xie, Shangran; Russell, Philip St. J.

    2016-12-01

    Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

  7. Investigation of high-contrast velocity selective optical pumping resonance at the cycling transition of Cs using fluorescence technique

    Science.gov (United States)

    Dey, Saswati; Ray, Biswajit; Ghosh, Pradip Narayan; Cartaleva, Stefka; Slavov, Dimitar

    2015-12-01

    A high contrast (∼48%) Velocity Selective Optical Pumping (VSOP) resonance at the closed transition Fg=4→Fe=5 of Cs-D2 line is obtained in the fluorescence signal under co-propagating pump-probe configuration. We use a 5.2 μm cell operating at reduced temperature (∼55 °C) and the intensity of the pump-laser is kept lower than that of the probe-laser. The observed sharp narrow structure is suitable for side-arms frequency-locking of the cooling- (i.e. probe-) laser in a cold atom experiment, with possibility for "-Γ" to "-4Γ" red-detuning and "+Γ" to "+10Γ" blue-detuning using the standard properties of the commercially available electronics. We have developed a theoretical model corresponding to the thin cell, incorporating the atomic time-of-flight dependent optical pumping decay rate to describe the dimensional anisotropy of the thin cell. The model shows good qualitative agreement with the observation and simulates as well the cases of cells with smaller thickness. It also describes correctly the temperature dependence of the line broadening and shows the potential for further optimization and red-shift detuning above "-4Γ". It may be of interest for further development of miniaturized modules, like the recently developed portable small magneto-optical traps.

  8. An optically pumped 2.5 μm GeSn laser on Si operating at 110 K

    Science.gov (United States)

    Al-Kabi, Sattar; Ghetmiri, Seyed Amir; Margetis, Joe; Pham, Thach; Zhou, Yiyin; Dou, Wei; Collier, Bria; Quinde, Randy; Du, Wei; Mosleh, Aboozar; Liu, Jifeng; Sun, Greg; Soref, Richard A.; Tolle, John; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed A.; Yu, Shui-Qing

    2016-10-01

    This paper reports the demonstration of optically pumped GeSn edge-emitting lasers grown on Si substrates. The whole device structures were grown by an industry standard chemical vapor deposition reactor using the low cost commercially available precursors SnCl4 and GeH4 in a single run epitaxy process. Temperature-dependent characteristics of laser-output versus pumping-laser-input showed lasing operation up to 110 K. The 10 K lasing threshold and wavelength were measured as 68 kW/cm2 and 2476 nm, respectively. Lasing characteristic temperature (T0) was extracted as 65 K.

  9. Reduced models and design principles for half-harmonic generation in synchronously-pumped optical parametric oscillators

    CERN Document Server

    Hamerly, Ryan; Jankowski, Marc; Fejer, Martin M; Yamamoto, Yoshihisa; Mabuchi, Hideo

    2016-01-01

    We develop reduced models that describe half-harmonic generation in a synchronously-pumped optical parametric oscillator above threshold, where nonlinearity, dispersion, and group-velocity mismatch are all relevant. These models are based on (1) an eigenmode expansion for low pump powers, (2) a simulton-like sech-pulse ansatz for intermediate powers, and (3) dispersionless box-shaped pulses for high powers. Analytic formulas for pulse compression, degenerate vs. nondegenerate operation, and stability are derived and compared to numerical and experimental results.

  10. PERFORMANCE ANALYSIS OF DIFFERENT ERBIUM DOPED FIBER BASED CODIRECTIONALLY PUMPED WDMSYSTEMS OPERATING IN OPTICAL WIDE-BAND

    Directory of Open Access Journals (Sweden)

    RICKY ANTHONY

    2012-02-01

    Full Text Available In this paper, simulation studies for different types of erbium doped fiber amplifier (EDFA based codirectionally pumped systems, operating in C and L band have been analyzed for wave division multiplexing (WDM, which is in accordance with ITU standards. The natural gain and noise figure (NF for variable pump powers at 0.03W, 0.06W, 0.12W, 0.18W and 0.24W were obtained. A comparative study of these fiberamplifiers using a figure of merit (FOM, in terms of gain uniformity in the given optical band was discussed.

  11. Performance Optimization of the Multi-Pumped Raman Optical Amplifier using MOICA

    Directory of Open Access Journals (Sweden)

    Mohsen Katebi Jahromi

    2016-08-01

    Full Text Available In order to achieve the best gain profile for multi pump distributed Raman amplifiers in Wavelength Division Multiplexing (WDM transmission systems, the power and wavelength of pumps, the type of pumping configuration and the number of pump signals are the most important factors. In this paper, using a Multi-Objective Imperialist Competition Optimization Algorithm (MOICA with lowest power consumption and lowest number of pumps, we propose the most uniform gain profile for two types of pumping configurations in S- band and compare the results. Considering the design conditions including the type of pumping configuration, fiber length, fiber type and number of pump signals and using the multi-objective algorithm, we propose a method which can be used to achieve a gain level in which the amplifier has the lowest power consumption and lowest gain ripple. According to this, we can design a powerful WDM transmission system by Distributed Raman Amplifier (DRA with a good performance and efficiency.

  12. Generation of synchronized signal and pump pulses for an optical parametric chirped pulse amplification based multi-terawatt Nd:glass laser system

    Indian Academy of Sciences (India)

    M Raghuramaiah; R K Patidar; R A Joshi; P A Naik; P D Gupta

    2010-11-01

    Synchronized signal (650 ps) and pump (1.3 ns) pulses were generated using 4-pass geometry in a grating pair based pulse stretcher unit. The pump pulse has been further amplified in a high gain regenerative amplifier. This amplified pulse was used as the pump in an optical parametric chirped pulse amplification based Nd:glass laser system. As the chirped signal pulse and the pump pulse originated from the same oscillator, the time jitter between the pump pulse and the signal pulse can be <50 ps.

  13. Frequency dependence of the pump-to-signal RIN transfer in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Pakarzadeh Dezfuli Nezhad, Hassan; Rottwitt, Karsten; Zakery, A.

    2009-01-01

    Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams.......Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams....

  14. Efficient OPSL-pumped mode-locked Yb:Lu2O3 laser with 67% optical-to-optical efficiency

    Science.gov (United States)

    Heuer, Alexander M.; Saraceno, Clara J.; Beil, Kolja; Huber, Günter; Kränkel, Christian

    2016-01-01

    We present a mode-locked Yb:Lu2O3 laser with up to 67% of optical-to-optical efficiency. By utilizing a high brightness optically pumped semiconductor laser (OPSL) as a pump source and using a semiconductor saturable absorber mirror (SESAM) we obtained self-starting mode locking. A pulse duration of 571 fs at 4.73 W of average output power with an optical-to-optical efficiency of 67% was achieved. In a slightly different cavity configuration the pulse duration was reduced to 313 fs at 2.16 W of average output power. In both cases the pulse duration was longer than the Fourier limit and the spectrum supports significantly shorter pulse durations. The laser wavelength is centered at 1034 nm and the repetition rate is 100.76 MHz in both cases. In continuous wave fundamental mode operation the optical-to-optical efficiency was as high as 78% with output powers exceeding 5 W.

  15. Heterodyne pump-probe and four-wave mixing in semiconductor optical amplifiers using balanced lock-in detection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper;

    1999-01-01

    We demonstrate a new detection scheme for pump-probe and four-wave mixing heterodyne experiments, using balanced detection and a dual-phase lock-in for spectral filtering. The technique allows the use of low repetition-rate laser systems, as is demonstrated on an InGaAsP/InP bulk optical amplifier...... at 1.53 mym. Ultrafast pump-induced changes in the amplitude and phase of the transmitted probe signal are simultaneously measured, going from small to large signal changes and with no need of an absolute phase calibration, showing the versatility and the sensitivity of this detection scheme....... The results for small perturbations are consistent with previous pump-probe experiments reported in literature. Time-resolved four-wave mixing in the absorption regime of the device is measured, and compared with numerical simulations, indicating a 100 fs dephasing time....

  16. Synchronously Pumped Femtosecond Optical Parametric Oscillator Based on MgO-Doped Periodically Poled LiNbO3

    Institute of Scientific and Technical Information of China (English)

    ZHU Jiang-Feng; ZHONG Xin; TENG Hao; SUN Jing-Hua; WEI Zhi-Yi

    2007-01-01

    We report a femtosecond optical parametric oscillator based on MgO-doped PPLN synchronously pumped by a mode-locked Ti:sapphire laser. The wavelengths of the signal and idler are continuously tuned from 1100 to 1300 nm and from 2080 to 2930 nm, respectively, by changing the pump wavelength and the OPO cavity length.The maximum signal output power of 130 mW at the wavelength of 1225 nm is obtained, pumped by 900 mW of 800nm laser radiation. This corresponds to a total conversion efficiency of 22.1%. The signal pulse duration is measured to be 167fs by intensity autocorrelation with chirped mirrors for intracavity dispersion compensation.

  17. Threshold characteristic of intracavity optical parametric oscillator pumped by all-solid-state Q-switched laser

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Degang Xu; Yizhong Yu; Wuqi Wen; Xifu Li; Jianquan Yao

    2008-01-01

    We derive the threshold pump intensity for a singly resonant intracavity optical parametric oscillator (IOPO)based on a temporal coupled field model.Particular attention is Paid to the dependence of the intracavity singly resonant OPO(SRO)threshold intensity on the signal wave output coupling.Meanwhile,a Nd:YAG laser pumped KTiOPO4(KTP)IOPO for eye-safe laser output is studied experimentally.The experiment is performed with four signal wave output reflectivities of 60%,70%,80%,and 90%,respectively.The measured values are in good agreement with the theoretical results.With an output coupler reflectivity of 80%,a peak power of 70 kW at 1572 nm has been obtained at a repetition rate of 3.5 kHz.The pulse width is 4.9 ns.Such investigation is helpful to identifying suitable operational regime of low pump intensity.

  18. Probing of free and localized excitons and trions in atomically thin WSe2, WS2, MoSe2 and MoS2 in photoluminescence and reflectivity experiments

    Science.gov (United States)

    Jadczak, J.; Kutrowska-Girzycka, J.; Kapuściński, P.; Huang, Y. S.; Wójs, A.; Bryja, L.

    2017-09-01

    We report on detailed temperature dependent (T = 7–295 K) optical spectroscopy studies of WSe2, WS2, MoSe2 and MoS2 monolayers exfoliated onto the same SiO2/Si substrate. In the high energy region of absorption type (reflectivity contrast—RC) and emission (photo-luminescence—PL) spectra of all the monolayers resonances related to the neutral and charged excitons (X and T) are detected in the entire measured temperature range. The optical amplitudes of excitons and trions strongly depend on the temperature and two dimensional carrier gas (2DCG) concentration. In the low energy PL spectra of WSe2 and WS2 we detect a group of lines (L) which dominates the spectra at low temperatures but rapidly quenches with the increase in the temperature. Interestingly, in the same energy range of the RC spectra recorded for WS2, we observe an additional line (L 0), which behaves in the same way as the L lines in the PL spectra. The optical amplitude of L 0 and T resonances in the RC spectra strongly increases with the growth of the 2DCG concentration. On the base of these observations we identify the L 0 resonance in the RC spectra as arising from the fine structure of the trion. We also propose that the line interpreted previously in PL spectra of WSe2 and WS2 as related to the biexciton emission is a superposition of the biexciton, trion and localized exciton emission. We find that with the temperature increase from 7–295 K the total PL intensity decreases moderately in WSe2 and WS2, strongly in MoS2 and dramatically in MoSe2.

  19. Single-resonance optical pumping spectroscopy and application in dressed-state measurement with atomic vapor cell at room temperature.

    Science.gov (United States)

    Liang, Qiangbing; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

    2010-06-21

    By monitoring the transmission of probe laser beam (also served as coupling laser beam) which is locked to a cycling hyperfine transition of cesium D(2) line, while pumping laser is scanned across cesium D(1) or D(2) lines, the single-resonance optical pumping (SROP) spectra are obtained with atomic vapor cell. The SROP spectra indicate the variation of the zero-velocity atoms population of one hyperfine fold of ground state, which is optically pumped into another hyperfine fold of ground state by pumping laser. With the virtue of Doppler-free linewidth, high signal-to-noise ratio (SNR), flat background and elimination of crossover resonance lines (CRLs), the SROP spectra with atomic vapor cell around room temperature can be employed to measure dressed-state splitting of ground state, which is normally detected with laser-cooled atomic sample only, even if the dressed-state splitting is much smaller than the Doppler-broaden linewidth at room temperature.

  20. High Photoluminescence Efficiency and Optically Pumped Lasing in Solution-Processed Mixed Halide Perovskite Semiconductors.

    Science.gov (United States)

    Deschler, Felix; Price, Michael; Pathak, Sandeep; Klintberg, Lina E; Jarausch, David-Dominik; Higler, Ruben; Hüttner, Sven; Leijtens, Tomas; Stranks, Samuel D; Snaith, Henry J; Atatüre, Mete; Phillips, Richard T; Friend, Richard H

    2014-04-17

    The study of the photophysical properties of organic-metallic lead halide perovskites, which demonstrate excellent photovoltaic performance in devices with electron- and hole-accepting layers, helps to understand their charge photogeneration and recombination mechanism and unravels their potential for other optoelectronic applications. We report surprisingly high photoluminescence (PL) quantum efficiencies, up to 70%, in these solution-processed crystalline films. We find that photoexcitation in the pristine CH3NH3PbI3-xClx perovskite results in free charge carrier formation within 1 ps and that these free charge carriers undergo bimolecular recombination on time scales of 10s to 100s of ns. To exemplify the high luminescence yield of the CH3NH3PbI3-xClx perovskite, we construct and demonstrate the operation of an optically pumped vertical cavity laser comprising a layer of perovskite between a dielectric mirror and evaporated gold top mirrors. These long carrier lifetimes together with exceptionally high luminescence yield are unprecedented in such simply prepared inorganic semiconductors, and we note that these properties are ideally suited for photovoltaic diode operation.

  1. Characterization of elastic interactions in GaAs/Si composites by optically pumped nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Ryan M.; Tokarski, John T.; McCarthy, Lauren A.; Bowers, Clifford R., E-mail: bowers@chem.ufl.edu [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States); Stanton, Christopher J. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

    2016-08-28

    Elastic interactions in GaAs/Si bilayer composite structures were studied by optically pumped nuclear magnetic resonance (OPNMR). The composites were fabricated by epoxy bonding of a single crystal of GaAs to a single crystal of Si at 373 K followed by selective chemical etching of the GaAs at room temperature to obtain a series of samples with GaAs thickness varying from 37 μm to 635 μm, while the Si support thickness remained fixed at 650 μm. Upon cooling to below 10 K, a biaxial tensile stress developed in the GaAs film due to differential thermal contraction. The strain perpendicular to the plane of the bilayer and localized near the surface of the GaAs was deduced from the quadrupolar splitting of the Gallium-71 OPNMR resonance. Strain relaxation by bowing of the composite was observed to an extent that depended on the relative thickness of the GaAs and Si layers. The variation of the strain with GaAs layer thickness was found to be in good agreement with a general analytical model for the elastic relationships in composite media.

  2. Optically pumped lasing in single crystals of organometal halide perovskites prepared by cast-capping method

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Van-Cao; Katsuki, Hiroyuki; Yanagi, Hisao, E-mail: yanagi@ms.naist.jp [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Sasaki, Fumio [Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2016-06-27

    A simple “cast-capping” method is adopted to prepare single-crystal perovskites of methyl ammonium lead bromide (CH{sub 3}NH{sub 3}PbBr{sub 3}). By capping a CH{sub 3}NH{sub 3}PbBr{sub 3} solution casted on one substrate with another substrate such as glass, mica, and distributed Bragg reflector (DBR), the slow evaporation of solvent enables large-size cubic crystals to grow between the two substrates. Under optical pumping, edge-emitting lasing is observed based on Fabry–Pérot resonation between parallel side facets of a strip-shaped crystal typically with a lateral cavity length of a few tens of μm. On the other hand, vertical-cavity surface-emitting lasing (VCSEL) is obtained from a planar crystal grown between two DBRs with a cavity thickness of a few μm. Simultaneous detection of those edge- and surface-emissions reveals that the threshold excitation fluence of VCSEL is higher than that of the edge-emitting lasing due to thickness gradient in the planar crystal.

  3. Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz

    Science.gov (United States)

    Aadhi, A.; Sharma, Varun; Chaitanya, N. Apurv; Samanta, G. K.

    2017-01-01

    We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz. PMID:28262823

  4. Fiber-laser-based green-pumped picosecond MgO:sPPLT optical parametric oscillator.

    Science.gov (United States)

    Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2013-12-15

    We report a stable, high-power, picosecond optical parametric oscillator (OPO) at 160 MHz repetition rate synchronously pumped by a frequency-doubled mode-locked Yb-fiber laser at 532 nm and tunable in the near-infrared, across 874-1008 nm (signal) and 1126-1359 nm (idler). Using a 30-mm-long MgO:sPPLT crystal, the OPO provides average output power up to 780 mW in the signal at 918.58 nm and 600 mW in the idler at 1242 nm. The device operates stably over many days, even close to degeneracy, exhibiting passive long-term power stability better than 1.8% rms in the signal and 2.4% rms in the idler over 2.5 h at a temperature of 55°C. We investigate spectral and temporal characteristics of the signal pulses under different conditions and demonstrate cavity-length tuning enabled by the dispersion properties of MgO:sPPLT. The output signal pulses have a duration of 2.4 ps at 967 nm.

  5. All-optical logical gates based on pump-induced resonant nonlinearity in an erbium-doped fiber coupler.

    Science.gov (United States)

    Li, Qiliang; Zhang, Zhen; Li, Dongqiang; Zhu, Mengyun; Tang, Xianghong; Li, Shuqin

    2014-12-01

    In this paper, we theoretically investigate all-optical logical gates based on the pump-induced resonant nonlinearity in an erbium-doped fiber coupler. The resonant nonlinearity yielded by the optical transitions between the (4)I(15/2) states and (4)I(13/2) states in Er(3+) induces the refractive index to change, which leads to switching between two output ports. First, we do a study on the switching performance, and calculate the extinction ratio (Xratio) of the device. Second, using the Xratio, we obtain the truth tables of the device. The results reveal that compared with other undoped nonlinear couplers, the erbium-doped fiber coupler can drop the switching threshold power. We also obtain different logic gates and logic operations in the cases of the same phase and different phase of two initial signals by changing the pump power.

  6. Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

    Science.gov (United States)

    Norris, G; McConnell, G

    2010-03-01

    A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

  7. Withdrawal of Chinese Physics Letters 26 (2009) 114209 "A Sensitive Scheme to Observe Weak Photo-Refraction Effects in Some Nonlinear Optical Crystals Pumped by Ultrashort Optical Pulses"

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang

    2011-01-01

    @@ This paper has been retracted because Fig.2 is copied from an earlier paper, "Interband photorefrac- tive effect in β-BBO crystal due to multiphoton exci- tation by intense ultrashort optical pulses" by Shix- iang Xu et al., which appeared in Optics Express 15 (2007) 10576, and its Figs.3 and 4 also present simi- lar data as in Figs.3 and 4 of the same Optics Express paper though they are measured at a different pump- ing power.This paper includes the first meaningful measurements of the photorefractive effect in BIBO and LBO crystals by intense ultrashort optical pulses, the first explanation of the phase-matching effect on the measurement of the photorefractive effect in BBO crystal and the reduction of pumping beam intensity of the second harmonic generator in the experimental setup to mitigate the effect of the nonlinear instability on our measurements.However, I admit, the Chinese Physics Letter paper contains serious replication with- out proper citation.%This paper has been retracted because Fig. 2 is copied from an earlier paper, "Interband photorefrac-tive effect in /3-BBO crystal due to multiphoton excitation by intense ultrashort optical pulses" by Shix-iang Xu et al, which appeared in Optics Express 15 (2007) 10576, and its Figs. 3 and 4 also present similar data as in Figs. 3 and 4 of the same Optics Express paper though they are measured at a different pumping power. This paper includes the first meaningful measurements of the photorefractive effect in BIBO and LBO crystals by intense ultrashort optical pulses, the first explanation of the phase-matching effect on the measurement of the photorefractive effect in BBO crystal and the reduction of pumping beam intensityof the second harmonic generator in the experimental setup to mitigate the effect of the nonlinear instability on our measurements. However, I admit, the Chinese Physics Letter paper contains serious replication without proper citation.I am so sorry for my faults and nescience. I alone

  8. Influence of light polarization on the dynamics of optically pumped lasers

    Energy Technology Data Exchange (ETDEWEB)

    Arjona, M.; Corbalan, R. (Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)); Laguarta, F.; Pujol, J. (Departament d' Optica i Optometria, Universitat Politecnica de Catalunya, 08222 Terrassa (Spain)); Vilaseca, R. (Departament I. D' Optica, Universitat de Valencia, 46100 Burjassot (Spain))

    1990-06-01

    The dynamic behavior of a coherently pumped ring laser with a homogeneously broadened four-level medium is analyzed theoretically, considering linearly polarized pump and generated laser beams. The laser is shown to be much more stable when these polarizations are parallel than when they are orthogonal. In the latter case the instability pump threshold can be as low as four times the first laser threshold, and the laser dynamics shows Lorenz-type features.

  9. Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

    Directory of Open Access Journals (Sweden)

    M. J. Kosch

    2005-07-01

    Full Text Available High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.

    Keywords. Active experiments – Auroral ionosphere – Wave-particle interactions

  10. Sub-nanosecond periodically poled lithium niobate optical parametric generator and amplifier pumped by an actively Q-switched diode-pumped Nd:YAG microlaser

    Science.gov (United States)

    Liu, L.; Wang, H. Y.; Ning, Y.; Shen, C.; Si, L.; Yang, Y.; Bao, Q. L.; Ren, G.

    2017-05-01

    A sub-nanosecond seeded optical parametric generator (OPG) based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal is presented. Pumped by an actively Q-switched diode-pumped 1 kHz, 1064 nm, Nd:YAG microlaser and seeded with a low power distributed feedback (DFB) diode continuous-wave (CW) laser, the OPG generated an output energy of 41.4 µJ and 681 ps pulse duration for the signal at 1652.4 nm, achieving a quantum conversion efficiency of 61.2% and a slope efficiency of 41.8%. Signal tuning was achieved from 1651.0 to 1652.4 nm by tuning the seed-laser current. The FWHM of the signal spectrum was approximately from 35 nm to 0.5 nm by injection seed laser. The SHG doubled the frequency of OPG signal to produce a output energy of 12 µJ with the energy conversion efficiency of 29.0% and tunanble wavelength near 826 nm.

  11. Optical and electrical characteristics of chromium- and iron-doped zinc selenide thin film and bulk materials for optically and electrically pumped lasers

    Science.gov (United States)

    Gallian, Andrew

    This work is devoted to evaluating new laser systems based upon chromium and iron doped ZnSe structures. These systems are based upon new materials and pumping schemes. These topics can be broken down into three major subgroups: new materials based upon Cr2+:ZnSe, Fe2+:ZnSe lasers and pump sources, and electrically pumped Cr2+:ZnSe systems. Both hot-pressed ceramic and thin film Cr2+:ZnSe samples were evaluated for their potential as laser gain media. This work entailed spectroscopic analysis of both their absorption and emission spectra as well as characterizing their lifetime of luminescence. For hot-pressed ceramic Cr2+:ZnSe the samples were tested in a laser cavity and proven to be the first laser system in the mid-IR to be demonstrated based upon hot-pressed Cr2+:ZnSe. Thin film Cr2+:ZnSe was determined to have different spectroscopic characteristics for luminescence compared to reference bulk samples. This difference is attributed to the location of all of the optical centers within a Fabry-Perot cavity formed by the film surface and the wafer on which it was deposited. Fe2+:ZnSe laser demonstration at room temperature is presented. This laser operates in a spectral region of great interest for spectroscopy. To develop this laser system new pumping systems were required. Such systems as passively Q-switched Er:YSGG and Stokes Stimulated Raman Scattering from a D2 cell are described in great depth. Electrically pumped Transition Metal 2+:II-VI systems are ideal for small portable spectroscopic and scientific tools. The elimination of an optical pump source removes many complications of other systems including, complications due to having a second laser. This work was approached by modeling electrically motivated transitions with sub-band optical excitation. Lasing of Cr 2+:ZnSe was achieved using a 532 nm pump source. This result, in combination with photo-current and photo-Hall measurements, led to the development of some theories explaining possible

  12. Superradiant dye solution laser with two-photon picosecond optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Prokhorenko, V.I.; Tikhonov, E.A.; Shpak, M.T.

    1981-01-01

    A superradiant (superfluorescent) dye solution laser with two-photon picosecond pumping was constructed for the first time. A preliminary study was made of the principal characteristics of the output radiation of this laser which performed up-conversion of the frequency of the pump radiation. The physical mechanisms governing the operation of lasers of this type were analyzed.

  13. Phase quadrature discrimination based on three-pump four-wave mixing in nonlinear optical fibers.

    Science.gov (United States)

    Baillot, Maxime; Gay, Mathilde; Peucheret, Christophe; Michel, Joindot; Chartier, Thierry

    2016-11-14

    We theoretically and experimentally study the principle of phase-sensitive frequency conversion in a highly-nonlinear fiber using three pump waves. This mechanism, originally demonstrated with four continuous-wave pumps and a signal wave, is based on four-wave mixing and enables to convert the two quadrature components of the signal to different frequencies. In this work, we derive a set of two simple equations to describe this mechanism and find analytic solutions. We show that only three pumps are required, instead of four as originally proposed. We give simple relations to determine the initial conditions for the power levels and the phases of the pumps. To validate this approach, we perform an experimental demonstration of the three-pump scheme and find excellent agreement with the theory.

  14. The mesospheric sodium layer as a remotely, optically pumped magnetometer for investigation of Birkeland currents

    Science.gov (United States)

    Johnsen, Magnar G.; Matzka, Jürgen; Hoppe, Ulf-Peter

    2016-04-01

    By means of optical pumping, it is possible to use the naturally occurring sodium layer in the mesosphere to measure Earth's scalar magnetic field at ~90 km above ground. This is an altitude not accessible by other means than rockets, which only will provide point measurements of very short time scales. We are planning to modify the sodium lidar at ALOMAR in Northern Norway to be able, for the first time, to measure and monitor the magnetic field in situ in the high latitude mesosphere over longer time scales. The planned modifications to the lidar instrument will allow alternating between the new magnetometer mode and its present mode for atmospheric temperatures and winds. The technique, which has been proposed earlier for measurements at low or mid-latitudes for studies of Earth's internal magnetic field, will in our project be applied to high latitudes in the auroral zone. This opens for a completely new domain of measurements of externally generated geomagnetic variations related to currents in the magnetosphere-ionosphere system. In particular, we aim to measure the magnetic field variations in close vicinity to Birkeland currents associated with particle precipitation events penetrating to altitudes below 90 km and small-scale, discrete auroral arcs. It is, furthermore, anticipated that it will be possible to detect horizontal current structures in the E-layer on much smaller length scales than it is presently possible from ground observations alone. During the project we plan take advantage of the rich space science infrastructure located in northern Norway, including ALOMAR, EISCAT and the Tromsø Geophysical Observatory magnetometer network. If possible, we also aim to make measurements in conjunction with overpasses of the SWARM satellites.

  15. Optical remote sensing of the thermosphere with HF pumped artificial airglow

    Science.gov (United States)

    Bernhardt, P. A.; Wong, M.; Huba, J. D.; Fejer, B. G.; Wagner, L. S.; Goldstein, J. A.; Selcher, C. A.; Frolov, V. L.; Sergeev, E. N.

    2000-05-01

    Optical emissions excited by high-power radio waves in the ionosphere can be used to measure a wide variety of parameters in the thermosphere. Powerful high-frequency (HF) radio waves produce energetic electrons in the region where the waves reflect in the F region. These hot or suprathermal electrons collide with atomic oxygen atoms to produce localized regions of metastable O(1D) and O(1S) atoms. These metastables subsequently radiate 630.0 and 557.7 nm, respectively, to produce clouds of HF pumped artificial airglow (HPAA). The shapes of the HPAA clouds are determined by the structure of large-scale (~10 km) plasma irregularities that occur naturally or that develop during ionospheric heating. When the HF wave is operated continuously, the motion of the airglow clouds follows the E×B drift of the plasma. When the HF wave is turned off, the airglow clouds decay by collisional quenching and radiation, expand by neutral diffusion, and drift in response to neutral winds. Images of HPAA clouds, obtained using both continuous and stepped radio wave transmissions, are processed to yield the electric fields, neutral wind vectors, and diffusion coefficients in the upper atmosphere. This technique is illustrated using data that were obtained in March 1993 and 1995 at the ionospheric modification facility near Nizhny Novgorod, Russia. Analysis of HPAA clouds yields zonal plasma drifts of 70 m s-1 eastward at night. On the basis of artificial airglow from energetic electrons generated at 260 km the zonal neutral wind speed was estimated to be 96 m s-1 and the O(1D) diffusion coefficient was determined to be between 0.8 and 1.4×1011cm2s-1. The quenched lifetime of the O(1D) was determined to be 29.4 s. The diffusion and quenching rates are directly related to the atomic and molecular concentrations in the thermosphere. Improvements in the remote-sensing technique may be obtained if the intensity of the artificial airglow emissions is increased. High-power radio

  16. Few-cycle, Broadband, Mid-infrared Optical Parametric Oscillator Pumped by a 20-fs Ti:sapphire Laser

    CERN Document Server

    Kumar, Suddapalli Chaitanya; Ideguchi, Takuro; Yan, Ming; Holzner, Simon; Hänsch, Theodor W; Picqué, Nathalie; Ebrahim-Zadeh, Majid

    2014-01-01

    We report a few-cycle, broadband, singly-resonant optical parametric oscillator (OPO) for the mid-infrared based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20-fs Ti:sapphire laser. By using crystal interaction lengths as short as 250 um, and careful dispersion management of input pump pulses and the OPO resonator, near-transform-limited, few-cycle idler pulses tunable across the mid-infrared have been generated, with as few as 3.7 optical cycles at 2682 nm. The OPO can be continuously tuned over 2179-3732 nm by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spaning over 422 nm (FWHM) recorded at 3732 nm. We investigate the effect of crystal length on spectral bandwidth and pulse duration at a fixed wavelength, confirming near-transform-limited idler pulses for all grating interaction lengths. By locking the repetition frequency of the pump laser to a radio-frequency reference, and with...

  17. The features of the optical pumping active fibers with three-piece inner clad

    Science.gov (United States)

    Bochkov, Alexander V.; Slobozhanina, Mariya G.

    2017-01-01

    This paper presents simple model of distribution of the pump radiation in active three-piece inner clad fibers (GTWave3) and analytical solutions of the relevant differential equations. Based on these solutions has been produced the analysis of the dependence distribution of the pump radiation and value of the effective length GTWave3 from key parameters of this type of a fiber (the active-region absorption coefficient and the coupling coefficients). Also in work presents comparison of the pump distribution into the GTWave3 and GTWave2 (two-piece inner clad) fibers.

  18. Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Feit, M D; DeMange, P; Bude, J D; Demos, S G

    2007-10-18

    Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spatial overlap between the pump and probe pulses versus probe time delay and energy. Results of this proof-of-principle experimental work confirm that material modifications under extreme conditions created during a damage event include transient optical absorption. In addition, we found that the relaxation times of the induced absorption are very distinct for DKDP and SiO{sub 2} even under identical excitation conditions, on the order of 100 ns and 100 {micro}s, respectively.

  19. Observation and theoretical simulation of electromagnetically induced transparency and enhanced velocity selective optical pumping in cesium vapour in a micrometric thickness optical cell

    Science.gov (United States)

    Krasteva, A.; Ray, B.; Slavov, D.; Todorov, P.; Ghosh, P. N.; Mitra, S.; Cartaleva, S.

    2014-09-01

    Observation of electromagnetically induced transparency (EIT) and enhanced velocity selective optical pumping (VSOP) signals in a micrometric cell with cesium is reported. The line shape and non-linear features observed in the case of fluorescence in the direction parallel to the cell windows and the transmission spectra observed along the propagation direction of the probe beam show considerable differences in the spectral profile. A theoretical model based on five level optical Bloch equations is used to simulate the spectra. The Doppler convolution includes all possible orientations of atomic velocities with respect to the laser beam direction. Atoms moving nearly parallel to the windows and perpendicular to the collinear pump and probe beams have much lower Doppler shift and hence produce considerable narrowing of the Doppler background in the fluorescence spectra. The coherence decay rate is also low for such atoms as they do not meet with the cell walls. The simulated curves reproduce the observed sharp EIT peaks and enhanced broad VSOP signals for the closed probe transition in the fluorescence and absorption spectra. The observed effect of detuning of the pump frequency on the non-linear features is also reproduced by the simulation.

  20. Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

    2011-01-01

    The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

  1. Transport of electron beams and stability of optical windows in high-power e-beam-pumped krypton fluoride lasers

    Science.gov (United States)

    Zvorykin, V. D.; Arlantsev, S. V.; Bakaev, V. G.; Rantsev, O. V.; Sergeev, P. B.; Sychugov, G. V.; Tserkovnikov, A. Yu.

    2001-10-01

    Two of the key issues of a krypton fluoride (KrF) laser driver for inertial fusion energy are the development of long life, high transparency pressure foils (to isolate vacuum in the electron beam diode from a working gas in the laser chamber), and the development of durable, stable, optical windows. Both of these problems have been studied on the single-pulse e-beam-pumped KrF laser installation GARPUN. We have measured the transport of electron beams (300 keV, 50 kA, 100 ns, 10 × 100 cm) through aluminum-beryllium and titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 50-[mu]m thickness Al-Be and 20-[mu]m Ti foils had equal transmittance. However, in contrast to Ti foil, whose surface was strongly etched by fluorine, no surface modification nor fatal damages were observed for Al-Be foils after [similar]1000 laser shots and protracted fluorine exposure. We also measured the 8% reduction in the transmission of CaF2 windows under irradiation by scattered electrons when they were set at 8.5 cm apart from the e-beam-pumped region. However an applied magnetic field of [similar]0.1 T significantly reduced electron scattering both across and along the laser cell at typical pumping conditions with 1.5 atm pressure working gas. Thus the e-beam-induced absorption of laser radiation in optical windows might be fully eliminated in an e-beam-pumping scheme with magnetic field guiding.

  2. Dynamic range enhancement and amplitude regeneration in single pump fibre optic parametric amplifiers using DPSK modulation

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Lorenzen, Michael Rodas; Seoane, Jorge

    2008-01-01

    Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain.......Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain....

  3. Absorption-free optical pumping spin control with the quantum Zeno effect

    CERN Document Server

    Nakanishi, T; Kitano, M

    2002-01-01

    We show that atomic spin motion can be controlled by circularly polarized light without light absorption in the strong pumping limit. In this limit, the pumping light, which drives the empty spin state, destroys the Zeeman coherence effectively and freezes the coherent transition via the quantum Zeno effect. It is verified experimentally that the amount of light absorption decreases asymptotically to zero as the incident light intensity is increased.

  4. Direct electro-optical pumping for hybrid CdSe nanocrystal/III-nitride based nano-light-emitting diodes

    Science.gov (United States)

    Mikulics, M.; Arango, Y. C.; Winden, A.; Adam, R.; Hardtdegen, A.; Grützmacher, D.; Plinski, E.; Gregušová, D.; Novák, J.; Kordoš, P.; Moonshiram, A.; Marso, M.; Sofer, Z.; Lüth, H.; Hardtdegen, H.

    2016-02-01

    We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven InGaN/GaN nano-LEDs as the primary excitation source. To this end, a universal hybrid optoelectronic platform was developed for a large range of optically active nano- and mesoscopic structures. The advantage of the approach is that the emission of the nanocrystals can be electrically induced without the need of contacting them. The proof of principal was demonstrated for the electro-optical pumping of CdSe nanocrystals. The nano-LEDs with a diameter of 100 nm exhibit a very low current of ˜8 nA at 5 V bias which is several orders of magnitude smaller than for those conventionally used. The leakage currents in the device layout were typically in the range of 8 pA to 20 pA/cm2 at 5 V bias. The photon-photon down conversion efficiency was determined to be 27%. Microphotoluminescence and microelectroluminescence characterization demonstrate the potential for future optoelectronics and highly secure "green" information technology applications.

  5. An electro-optical timing diagnostic for pump-probe experiments at the free-electron laser in Hamburg FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Azima, Armin

    2009-07-15

    Femtosecond pump-probe experiments have extensively been used to follow atomic and molecular motion in time. The very intense extreme ultraviolet XUV light of the Free electron LASer in Hamburg FLASH facility allows to investigate fundamental processes such as direct one or few photon inner shell ionizations. A supplementary Ti:Sapphire near infrared femtosecond laser system allows to perform two-color pump-probe experiments with FLASH involving intense laser fields of hugely different photon energies. Within this work a bunch arrival measurement system has been built, which assists these two-color pump-probe experiments to reduce the temporal jitter of FLASH and to increase the temporal resolution. The diagnostic is based upon an electro-optical detection scheme and measures the relative arrival time between the Ti:Sapphire femtosecond pulse and the electron bunch, which generates the self-amplified by stimulated emission SASE XUV pulse in the undulator section of FLASH. Key feature of the diagnostic is a 150 m long glass fiber pulse transport line, which inflicts non-linear dispersion. A dispersion control system to compensate for this higher order dispersion has been developed including the control and programming of a spatial light phase modulator. It was possible to transport a 90 fs FWHM short near infrared femtosecond laser pulse Fourier limited by the dispersion compensated glass fiber. The electro-optical signal induced by the FLASH electron bunch was generated, characterized and optimized. The signal features beside the designated bunch arrival timing capability the additional possibility to measure the longitudinal electron bunch density distribution of an arbitrary bunch of FLASH in a single shot with a temporal resolution of below 100 fs RMS. Timing and bunch analysis capabilities of the developed diagnostic have been cross-checked with other comparable diagnostics at FLASH like the transversal deflecting cavity structure named LOLA. Finally, the

  6. Using tunnel junctions to grow monolithically integrated optically pumped semipolar III-nitride yellow quantum wells on top of electrically injected blue quantum wells.

    Science.gov (United States)

    Kowsz, Stacy J; Young, Erin C; Yonkee, Benjamin P; Pynn, Christopher D; Farrell, Robert M; Speck, James S; DenBaars, Steven P; Nakamura, Shuji

    2017-02-20

    We report a device that monolithically integrates optically pumped (20-21) III-nitride quantum wells (QWs) with 560 nm emission on top of electrically injected QWs with 450 nm emission. The higher temperature growth of the blue light-emitting diode (LED) was performed first, which prevented thermal damage to the higher indium content InGaN of the optically pumped QWs. A tunnel junction (TJ) was incorporated between the optically pumped and electrically injected QWs; this TJ enabled current spreading in the buried LED. Metalorganic chemical vapor deposition enabled the growth of InGaN QWs with high radiative efficiency, while molecular beam epitaxy was leveraged to achieve activated buried p-type GaN and the TJ. This initial device exhibited dichromatic optically polarized emission with a polarization ratio of 0.28. Future improvements in spectral distribution should enable phosphor-free polarized white light emission.

  7. Simultaneous subsecond hyperpolarization of the nuclear and electron spins of phosphorus in silicon by optical pumping of exciton transitions.

    Science.gov (United States)

    Yang, A; Steger, M; Sekiguchi, T; Thewalt, M L W; Ladd, T D; Itoh, K M; Riemann, H; Abrosimov, N V; Becker, P; Pohl, H-J

    2009-06-26

    We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

  8. Efficient 1 kHz femtosecond optical parametric amplification in BiB(3)O(6) pumped at 800 nm.

    Science.gov (United States)

    Ghotbi, Masood; Ebrahim-Zadeh, Majid; Petrov, Valentin; Tzankov, Pancho; Noack, Frank

    2006-10-30

    We demonstrate efficient operation of a tunable femtosecond optical parametric amplifier based on BiB(3)O(6) pumped at 800 nm by a 1 kHz Ti:sapphire regenerative amplifier. The idler wavelength coverage extends to beyond 3 mum and the pulse duration at this wavelength is of the order of 110 fs. This new nonlinear borate crystal offers exceptionally high nonlinearity, making it a very promising candidate for power scaling of such frequency converters in the near-IR.

  9. Sensitive determination of the spin polarization of optically pumped alkali-metal atoms using near-resonant light

    Science.gov (United States)

    Ding, Zhichao; Long, Xingwu; Yuan, Jie; Fan, Zhenfang; Luo, Hui

    2016-09-01

    A new method to measure the spin polarization of optically pumped alkali-metal atoms is demonstrated. Unlike the conventional method using far-detuned probe light, the near-resonant light with two specific frequencies was chosen. Because the Faraday rotation angle of this approach can be two orders of magnitude greater than that with the conventional method, this approach is more sensitive to the spin polarization. Based on the results of the experimental scheme, the spin polarization measurements are found to be in good agreement with the theoretical predictions, thereby demonstrating the feasibility of this approach.

  10. Bases for time-resolved probing of transient carrier dynamics by optical pump-probe scanning tunneling microscopy.

    Science.gov (United States)

    Yokota, Munenori; Yoshida, Shoji; Mera, Yutaka; Takeuchi, Osamu; Oigawa, Haruhiro; Shigekawa, Hidemi

    2013-10-07

    The tangled mechanism that produces optical pump-probe scanning tunneling microscopy spectra from semiconductors was analyzed by comparing model simulation data with experimental data. The nonlinearities reflected in the spectra, namely, the excitations generated by paired laser pulses with a delay time, the logarithmic relationship between carrier density and surface photovoltage (SPV), and the effect of the change in tunneling barrier height depending on SPV, were examined along with the delay-time-dependent integration process used in measurement. The optimum conditions required to realize reliable measurement, as well as the validity of the microscopy technique, were demonstrated for the first time.

  11. A measurement of the absolute neutron beam polarization produced by an optically pumped sup 3 He neutron spin filter

    CERN Document Server

    Rich, D R; Crawford, B E; Delheij, P P J; Espy, M A; Haseyama, T; Jones, G; Keith, C D; Knudson, J; Leuschner, M B; Masaike, A; Masuda, Y; Matsuda, Y; Penttilae, S I; Pomeroy, V R; Smith, D A; Snow, W M; Szymanski, J J; Stephenson, S L; Thompson, A K; Yuan, V

    2002-01-01

    The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized sup 3 He spin filter and a relative transmission measurement technique. sup 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method.

  12. Color superfluidity and trion formation in ultracold fermionic systems

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Akos [Institut fuer Theoretische Physik, Universitaet zu Koeln (Germany)

    2009-07-01

    We investigate the low temperature properties of the three component Hubbard model. This system might be realized by trapping 3 different hyperfine states of ultracold Li-6 atoms in optical lattices. Studies concerning the SU(3) symmetric attractive case based on a Gutzwiller variational method in d={infinity} suggest that there is a continuous phase transition happening between a weak coupling color superfluid and a strong coupling trionic ground state. We construct and investigate the properties of the quantum field theory describing this quantum phase transition.

  13. Optical parametric oscillators synchronously pumped by fundamental and second harmonic radiation of femtosecond Yb:KGW laser

    Science.gov (United States)

    StankevičiÅ«tÄ--, K.; PipinytÄ--, I.; Vengelis, J.; MarcinkevičiÅ«tÄ--, A.; Å uminas, R.; Grigonis, R.; Eckardt, R. C.; Sirutkaitis, V.

    2013-09-01

    We present experimental data obtained during investigation of synchronously pumped optical parametric oscillators (SPOPO's) pumped by fundamental (1030 nm) and second harmonic (515 nm) radiation of mode-locked Yb:KGW laser, providing 105 fs pulses at 76 MHz repetition rate with an average power of 4 W. Different nonlinear crystals such as beta barium borate (BBO), and periodically poled lithium niobate (PPLN) and MgO doped PPLN (MgO:PPLN) were tested to estimate wavelength tuning capabilities and SPOPO's efficiency. Rotation of BBO nonlinear crystal and SPOPO's cavity length variation and, in the case of SPOPO based on PPLN, change of grating period and cavity length allowed signal wavelength tuning in 630 - 1030 nm and 1350 - 1700 nm spectral ranges, respectively. Parametric light conversion from pump power to signal power efficiency was as high as 25 %. Including the idler pulses the tuning ranges were from 630 to 2400 nm and from 1350 to 4000 nm in case of BBO and PPLN crystals, respectively. SPOPO based on BBO wsithout intracavity group velocity dispersion (GVD) compensation generates longer than transform limited pulses, so SPOPO based on BBO with dispersive prisms were investigated.

  14. High-power, fiber-laser-pumped, picosecond optical parametric oscillator based on MgO:sPPLT.

    Science.gov (United States)

    Kumar, S Chaitanya; Ebrahim-Zadeh, M

    2011-12-19

    We report a stable, high-power, mid-infrared synchronously-pumped optical parametric oscillator (SPOPO) based on MgO:sPPLT, pumped by a 1064 nm, picosecond Yb-fiber laser operating at a repetition rate of 81.1 MHz. The singly resonant SPOPO is tunable over 1531-1642 nm (111 nm) in the near-infrared signal and 3022-3488 nm (466 nm) in the mid-infrared idler, providing a total tuning range of 577 nm. Careful optimization of output coupling results in a signal output power as high as 4.3 W at 1593 nm and a mid-infrared idler power of 2 W at 3204 nm for 13.4 W of pump power at a total extraction efficiency of 47%. The SPOPO can be operated near room temperature, down to 30 °C, and exhibits passive peak-to-peak power stability better than 8.6% at 1568 nm (signal) and 8.2% at 3310 nm (idler) over 13 hours at full power. The output signal pulses have duration of 17.5 ps, with a FWHM spectral bandwidth of 1.4 nm centered at 1568 nm.

  15. Effects of Pumping Sizes on THz Radiation Based on Ultrashort Light Pulse Optical Rectification for High Spatial Resolution T-Ray Imaging

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang; DAI Xiao-Ming; YANG Xiao-Hua; LI Jing-Zhen

    2008-01-01

    @@ We present our experimental studies on the effects of the pumping sizes on THz radiation based on ultrashort light pulse optical rectification for high spatial resolution T-Ray imaging.Our experiments show that high spatial resolution T-ray imaging requires both thin THz emitter and sample, and rigorous tolerance of the gap between the sample and the emitter, as well as small pumping size which usually much smaller compared with THz wavelength.Such a small pumping size results in dramatic decrease of the THz wave power, which originates from strong diffraction of THz wave, the depolarization of the focused tightly pumping beam, the spatial filtering of the emitter exit-surface, and the strong phase-mismatching between the pumping and the high spatial Fourier components of the THz signal, rather than two-photon absorption.

  16. 4-Azatricyclo[5.2.2.02,6]undecane-3,5,8-triones as potential pharmacological agents.

    Science.gov (United States)

    Kossakowski, Jerzy; Bielenica, Anna; Mirosław, Barbara; Kozioł, Anna E; Dybała, Izabela; Struga, Marta

    2008-08-06

    A series of twenty six arylpiperazine and aminoalkanol derivatives of 4-azatricyclo[5.2.2.0(2,6)]undecane-3,5,8-trione have been prepared. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells.

  17. 4-Azatricyclo[5.2.2.02,6]undecane-3,5,8-triones as Potential Pharmacological Agents

    Directory of Open Access Journals (Sweden)

    Marta Struga

    2008-08-01

    Full Text Available A series of twenty six arylpiperazine and aminoalkanol derivatives of 4-azatricyclo[ 5.2.2.02,6]undecane-3,5,8-trione have been prepared. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells.

  18. Optically pumped distributed feedback dye lasing with slide-coated TiO₂ inverse-opal slab as Bragg reflector.

    Science.gov (United States)

    Han, Sung Gu; Lim, Jongchul; Shin, Jinsub; Lee, Sung-Min; Park, Taiho; Yoon, Jongseung; Woo, Kyoungja; Lee, Hyunjung; Lee, Wonmok

    2014-08-15

    We demonstrate an optical amplification of organic dye within a TiO2 inverse-opal (IO) distributed feedback (DFB) reflector prepared by a slide-coating method. Highly reflective TiO2 IO film was fabricated by slide coating the binary aqueous dispersions of polystyrene microspheres and charge-stabilized TiO2 nanoparticles on a glass slide and subsequently removing the polymer-opal template. TiO2 IO film was infiltrated, in turn, with the solutions of DCM, a fluorescent dye in various solvents with different indices of refraction. Optical pumping by frequency-doubled Nd:YAG laser resulted in amplified spontaneous emission in each dye solution. In accordance with the semi-empirical simulation by the FDTD method, DCM in ethanol showed the best emission/stopband matching for the TiO2 IO film used in this study. Therefore, photo excitation of a DCM/ethanol cavity showed a single-mode DFB lasing at 640 nm wavelength at moderate pump energy.

  19. Novel electronic ferroelectricity in an organic charge-order insulator investigated with terahertz-pump optical-probe spectroscopy

    Science.gov (United States)

    Yamakawa, H.; Miyamoto, T.; Morimoto, T.; Yada, H.; Kinoshita, Y.; Sotome, M.; Kida, N.; Yamamoto, K.; Iwano, K.; Matsumoto, Y.; Watanabe, S.; Shimoi, Y.; Suda, M.; Yamamoto, H. M.; Mori, H.; Okamoto, H.

    2016-02-01

    In electronic-type ferroelectrics, where dipole moments produced by the variations of electron configurations are aligned, the polarization is expected to be rapidly controlled by electric fields. Such a feature can be used for high-speed electric-switching and memory devices. Electronic-type ferroelectrics include charge degrees of freedom, so that they are sometimes conductive, complicating dielectric measurements. This makes difficult the exploration of electronic-type ferroelectrics and the understanding of their ferroelectric nature. Here, we show unambiguous evidence for electronic ferroelectricity in the charge-order (CO) phase of a prototypical ET-based molecular compound, α-(ET)2I3 (ET:bis(ethylenedithio)tetrathiafulvalene), using a terahertz pulse as an external electric field. Terahertz-pump second-harmonic-generation(SHG)-probe and optical-reflectivity-probe spectroscopy reveal that the ferroelectric polarization originates from intermolecular charge transfers and is inclined 27° from the horizontal CO stripe. These features are qualitatively reproduced by the density-functional-theory calculation. After sub-picosecond polarization modulation by terahertz fields, prominent oscillations appear in the reflectivity but not in the SHG-probe results, suggesting that the CO is coupled with molecular displacements, while the ferroelectricity is electronic in nature. The results presented here demonstrate that terahertz-pump optical-probe spectroscopy is a powerful tool not only for rapidly controlling polarizations, but also for clarifying the mechanisms of ferroelectricity.

  20. Optically pumped infrared stimulated radiation in pr3+:Y2SiO5

    Institute of Scientific and Technical Information of China (English)

    Yanliang Zhang(张衍亮); Zhenrong Sun(孙真荣); Yuqiong Li(李玉琼); Liang'en Ding(丁良恩); Zugeng Wang(王祖赓)

    2003-01-01

    The infrared stimulated radiation of 1D2 → 3F.2 and 1D2 → 3H6 transitions in Pr3+:Y2SiO5 (YSO) viapulsed laser pumping has been observed. The threshold energy, temperature dependence and divergenceangle for the stimulated radiation are also measured.

  1. Designing optically pumped InGaN quantum wells with long wavelength emission for a phosphor-free device with polarized white-light emission

    Science.gov (United States)

    Kowsz, Stacy J.; Pynn, Christopher D.; Wu, Feng; Farrell, Robert M.; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji

    2016-02-01

    We report a semipolar III-nitride device in which an electrically injected blue light emitting diode optically pumps monolithic long wavelength emitting quantum wells (QWs) to create polarized white light. We have demonstrated an initial device with emission peaks at 440 nm and 560 nm from the electrically injected and optically pumped QWs, respectively. By tuning the ratio of blue to yellow, white light was measured with a polarization ratio of 0.40. High indium content InGaN is required for long wavelength emission but is difficult to achieve because it requires low growth temperatures and has a large lattice mismatch with GaN. This device design incorporates optically pumped QWs for long wavelength emission because they offer advantages over using electrically injected QWs. Optically pumped QWs do not have to be confined within a p-n junction, and carrier transport is not a concern. Thus, thick GaN barriers can be incorporated between multiple InGaN QWs to manage stress. Optically pumping long wavelength emitting QWs also eliminates high temperature steps that degrade high indium content InGaN but are required when growing p-GaN for an LED structure. Additionally, by eliminating electrical injection, the doping profile can instead be engineered to affect the emission wavelength. We discuss ongoing work focused on improving polarized white light emission by optimizing the optically pumped QWs. We consider the effects of growth conditions, including: trimethylindium (TMI) flow rate, InGaN growth rate, and growth temperature. We also examine the effects of epitaxial design, including: QW width, number of QWs, and doping.

  2. Fiber optic line for RoF systems with remote and local pump EDFA

    Science.gov (United States)

    Vinogradova, Irina L.; Sultanov, Albert K.; Meshkov, Ivan K.; Andrianova, Anna V.; Grakhova, Elizaveta P.; Ishmiyarov, Arsen A.; Zainullin, Airat R.

    2015-03-01

    The article is devoted to the research of a method providing positive chirp of a signal on a long-haul fiber optic line. The modeling of an optical pulse duration and its chirp functions on an offered segment has allowed to estimate the parameters of a segment - distance between regeneration points and capacity level of additional radiation. The method is interesting for high-speed transmission when there is no availability to use the electronic or fiber optic chromatic dispersion compensation modules.

  3. Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2-μm laser

    Institute of Scientific and Technical Information of China (English)

    Yuefeng Peng; Xingbin Wei; Weimin Wang

    2011-01-01

    @@ We present a 3-5 μm optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μm laser.The tuning curves of ZGP OPO are calculated.The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antirefiection coated at 2.1 and 3.7-4.6 μm, is cut as θ=53.5°, φ=0°.When the pump power of 2.1-μm polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type Ⅰ phase match.Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μm, respectively.Pulse duration is about 27 ns.Beam quality factor M2 is better than 1.8.The tunability of 3-5 μm can be achieved by changing the angle of the ZGP crystal.%We present a 3-5 μm optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μm laser. The tuning curves of ZGP OPO are calculated. The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7-4.6 μm, is cut as θ=53.5°, φ=0°. When the pump power of 2.1-μm polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type Ⅰ phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μm, respectively.Pulse duration is about 27 ns. Beam quality factor M2 is better than 1.8. The tunability of 3-5 μm can be achieved by changing the angle of the ZGP crystal.

  4. Optically pumped 5 microm IV-VI VECSEL with Al-heat spreader.

    Science.gov (United States)

    Rahim, M; Felder, F; Fill, M; Zogg, H

    2008-12-15

    Mid-infrared vertical external cavity surface emitting lasers (VECSELs) for 5 microm in wavelength have been realized. The active parts are of a simple structure, either a 2 microm thick PbTe gain layer or two 150 nm PbTe layers embedded in Pb(1-x)Eu(x)Te barriers. Epitaxial 2.5 pair Pb(1-y)Eu(y)Te/BaF(2) Bragg mirrors are employed to form the cavity, and an Al layer is deposited for improved heat dissipation. Emission up to 300 mW(p) is observed with microsecond pulses or 3 mW cw at 100 K is obtained. Quantum efficiency is up to 14%, and lasing occurs up to 175 K when pumped with a 1.55 microm wavelength pump laser.

  5. Diode-pumped intracavity optical parametric oscillator in pulsed and continuous-wave operation

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Skettrup, Torben; Petersen, O.B.;

    2002-01-01

    An intracavity optical parametric oscillator is investigated in pulsed and continuous-wave operation. The intracavity optical parametric oscillator is based on Yb:YAG as the laser material and a periodically poled lithium niobate crystal as the nonlinear material. Tuneable idler output powers above...

  6. Characterization of optically excited semiconductors by phase-resolved pump-probe spectroscopy; Charakterisierung optisch angeregter Halbleiter mit phasenaufgeloester Pump-Probe-Spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, M.

    2005-07-01

    This thesis aims to present new experimentally and theoretically verified statements about the many-body effects in thin Zinc Selenide layers and to discuss the various techniques applied in the experiments. Centred in this thesis is the investigation of ultrafast nonlinear effects in the response of thin Zinc Selenide layers on their optical excitation with ultrashort laser pulses. The experiments address the regime of quantum coherence and thermalisation of the excitation. In the energy range of the band gap the response is determined by the propagation of exciton polaritons in the samples. The dynamics of the interactions between the polaritons and the particles of the solid are investigated by conducting pump-probe experiments. This thesis extends and surpasses previous work in that the reflected light is completely analysed in its classical phase and amplitude. Thus all the information in the electromagnetic field in the temporal and spectral domain is available. It is found that especially not just the power spectrum of the reflected light is much structured but the spectral phase too. The spectral phase reflects directly the carrier-density dependent of the polariton dispersion while the temporal field, characterised by the beating of slowly propagating polaritons, does not show dramatic carrier-density depended changes. Phase resolved measurement of the reflected field is performed with the technique of Spectral Interferometry which is adapted to the experiment and tested on correctness. The measured electromagnetic fields are interpreted with classical and a semi-classical microscopic models. Further is shown how these results relate to recent microscopic quantum mechanical models. (orig.)

  7. Optical pumping and population transfer of nuclear-spin states of caesium atoms in high magnetic fields

    Institute of Scientific and Technical Information of China (English)

    Luo Jun; Sun Xian-Ping; Zeng Xi-Zhi; Zhan Ming-Sheng

    2007-01-01

    Nuclear-spin states of gaseous-state Cs atoms in the ground state are optically manipulated using a Ti:sapphire laser in a magnetic field of 1.516 T, in which optical coupling of the nuclear-spin states is achieved through hyperfine interactions between electrons and nuclei. The steady-state population distribution in the hyperfine Zeeman sublevels of the ground state is detected by using a tunable diode laser. Furthermore, the state population transfer among the of Cs in the ground state due to stochastic collisions between Cs atoms and buffer-gas molecules, is studied at different of the hyperfine interaction can strongly cause the state population transfer and spin-state interchange among the hyperfine Zeeman sublevels. The calculated results maybe explain the steady-state population in hyperfine Zeeman sublevels in terms of rates of optical-pumping, electron-spin flip, nuclear spin flip, and electron-nuclear spin flip-flop transitions among the hyperfine Zeeman sublevels of the ground state of Cs atoms. This method may be applied to the nuclear-spin-based solid-state quantum computation.

  8. Coherent Population Trapping Resonances in Buffer Gas-filled Cs Vapor Cells with Push-Pull Optical Pumping

    CERN Document Server

    Liu, Xiaochi; Guérandel, Stéphane; Gorecki, Christophe; de Clercq, Emeric; Boudot, Rodolphe

    2013-01-01

    We report on a theoretical study and experimental characterization of coherent population trapping (CPT) resonances in buffer gas-filled vapor cells with push-pull optical pumping (PPOP) on Cs D1 line. We point out that the push-pull interaction scheme is identical to the so-called lin per lin polarization scheme. Expressions of the relevant dark states, as well as of absorption, are reported. The experimental setup is based on the combination of a distributed feedback (DFB) diode laser, a pigtailed intensity Mach-Zehnder electro-optic modulator (MZ EOM) for optical sidebands generation and a Michelson-like interferometer. A microwave technique to stabilize the transfer function operating point of the MZ EOM is implemented for proper operation. A CPT resonance contrast as high as 78% is reported in a cm-scale cell for the magnetic-field insensitive clock transition. The impact of the laser intensity on the CPT clock signal key parameters (linewidth - contrast - linewidth/contrast ratio) is reported for three ...

  9. Efficient Compound-Cavity Eye-Safe KTP OPO at 1.57 μm Pumped by an Electro-Optic Q-Switched Nd: YAG Laser

    Institute of Scientific and Technical Information of China (English)

    ZHONG Kai; WANG Yu-Ye; XU De-Gang; GENG You-Fu; WANG Jing-Li; WANG Peng; YAO Jian-Quan

    2009-01-01

    An efficient high-energy eye-safe optical parametric oscillator (OPO) based on a type-Ⅱ non-critically phasematched KTP crystal is demonstrated.The KTP OPO is pumped by a quasi-cw diode side-pumped electrooptic Q-switched Nd:YAG laser in a compound-cavity configuration.The maximum output energy of the signal wavelength at 1.57 μm is 66.5 m J,corresponding to an electrical- to-optical conversion efficiency of 4.47% and an optical-to-optical conversion efficiency of 12.1%.The pulse width (FWHM) is about 3.6 ns with a peak power of 18.5 MW.The output energy is insensitive to repetition rate and demonstrates good stability.

  10. Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

    Science.gov (United States)

    Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

    2016-01-01

    We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

  11. 7/3 fractional quantum Hall effect: topology, trion excitations and edge states

    Science.gov (United States)

    Balram, Ajit C.; Wu, Ying-Hai; Sreejith, G. J.; Wójs, Arkadiusz; Jain, J. K.

    2013-03-01

    Exact diagonalization studies on finite systems show that the quasihole and quasiparticle excitations in the 7/3 fractional quantum Hall (FQH) state are qualitatively distinct from those of the 1/3 state, suggesting the possibility of different topological origins for the two states. We perform composite-fermion diagonalization on larger systems and also evaluate the entanglement spectrum, which shows that in spite of these strong finite size deviations, the 7/3 and 1/3 FQH states have the same topological structure in the thermodynamic limit. Nonetheless, there are substantial non-topological differences between the two, arising from the stronger residual interaction between composite fermions at 7/3. In particular, we show that the lowest energy charged excitations of the 7/3 state are complex trions of composite fermions, which have a much larger size than the charged excitations at 1/3. We discuss many observable consequences of our results.

  12. 19-core MCF transmission system using EDFA with shared core pumping coupled via free-space optics.

    Science.gov (United States)

    Sakaguchi, Jun; Klaus, Werner; Puttnam, Benjamin J; Mendinueta, José Manuel Delgado; Awaji, Yoshinari; Wada, Naoya; Tsuchida, Yukihiro; Maeda, Koichi; Tadakuma, Masateru; Imamura, Katsunori; Sugizaki, Ryuichi; Kobayashi, Tetsuya; Tottori, Yusaku; Watanabe, Masayuki; Jensen, R V

    2014-01-13

    We report the development of a space division multiplexed (SDM) transmission system consisting of a 19-core fiber and 19-core Erbium-doped fiber amplifier (EDFA). A new 19-core fiber with an improved core arrangement was employed to achieve a low aggregated inter-core crosstalk of -42 dB at 1550 nm over 30 km. The EDFA uses shared free-space optics for pump beam combining and isolation, thus is SDM transparent and has some potential for cost reduction. 19.6 dB to 23.3 dB gain and 6.0 dB to 7.0 dB noise figure were obtained for each SDM channel at 1550 nm. System feasibility for SDM transmission over 1200 km was demonstrated with 100 Gb/s PDM-QPSK signals.

  13. Photoexcitation of lasers and chemical reactions for NASA missions: A theoretical study. [optical pumping in high pressure gas

    Science.gov (United States)

    Javan, A.; Guerra, M.

    1981-01-01

    The possibility of obtaining CW laser oscillation by optical pumping in the infrared at an elevated gas pressure is reviewed. A specific example utilizing a mixture of CO and NO gases is included. The gas pressures considered are in excess of several atmospheres. Laser frequency tuning over a broad region becomes possible at such elevated gas pressures due to collisional broadening of the amplifying transitions. The prior-rate and surprisal analysis are applied to obtain detailed VV and VT rates for CO and NO molecules and the transfer rates in a CO-NO gas mixture. The analysis is capable of giving temperature dependence of the rate constants. Computer estimates of the rates are presented for vibrational levels up to v = 50. The results show that in the high-lying vibrational states the VV transfer rates with Delta nu = 2 become appreciable.

  14. Modeling of Vibration-to-Vibration and Vibration-to-Electronic Energy Transfer Processes in Optically Pumped Plasmas

    Science.gov (United States)

    Adamovich, Igor V.; Ploenjes, Elke; Palm, Peter; Rich, J. William; Chernukho, Andrey

    1998-10-01

    - The paper presents the results of modeling of the optical pumping experiments in CO/N2/O2/Ar mixtures. In these experiments, the low vibrational levels of carbon monoxide (vinfrared and ultraviolet radiation from the excited electronic states is measured by a high-resolution step-scan Fourier transform spectrometer. The kinetic model incorporates coupled master equation for the CO, N2, and O2 vibrational level populations, and Boltzmann equation for the electrons. The comparison of the experimental and synthetic time-resolved spectra allowed inference of the V-V exchange rates for CO-CO up to v=40, cross-sections for the energy transfer between the highly excited CO molecules and electrons, and V-V transfer rates for CO-N2 and CO-O2.

  15. Optimal Design of Dual-Pump Fibre-Optical Parametric Amplifiers with Dispersion Fluctuations Based on Hybrid Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    LIU Xue-Ming; LI Yan-He

    2005-01-01

    @@ Solutions of dual-pump fibre-optical parametric amplifiers (DP-FOPAs) with dispersion fluctuations are derived by using a matrix operator. Based on these solutions and a hybrid genetic algorithm, we have optimized threesection DP-FOPAs to increase the signal band and improve the gain uniformity. The optimizations demonstrate that when dispersion fluctuations are taken into account, the 44-nm signal band with the 0.37-dB ripple and over 14.8-dB gain can be obtained from the three-section DP-FOPA, instead of the lowest gain of ~13dB with the ripple of more than 15dB from the single-section DP-FOPA.

  16. Diode-end-pumped electro-optically Q-switched Nd:YLF slab laser.

    Science.gov (United States)

    Zhang, Hengli; Du, Keming; Li, Daijun; Shi, Peng; Wang, Yongdong; Diart, Robert

    2004-05-10

    We report a very compact Nd:YLF slab laser that is end pumped by a quasi-continuous-wave diode stack. A hybrid resonator is used to generate high output power in a near-diffraction-limited beam (i.e., a beam propogation M2 factor of less than 1.2). A pulse energy of 14.3 mJ was obtained with a pulse width of 8.5 ns at a repetition rate of 500 Hz, which corresponds to a Q-switched peak power of 1.68 MW.

  17. A pump driving liquid cooling circuit method for the aperture of an infrared cold optical system

    Science.gov (United States)

    Xie, RongJian

    2017-06-01

    To enhance the optical recognition and wavelength filtering of an infrared cold optical system, some lens need to be maintained within a certain temperature range, which requires specific thermal management of the aperture. A 250K liquid cooling circuit designed for this purpose is introduced, and the experimental results established and operated in a vacuum environmental simulation chamber is carried out and analyzed. A practical cooling power source of radiation cooling equipment is adopted and the sun exposure heat load is imitated by array of planar membrane heaters attached on the specific designed structure of the aperture. Controlling the aperture temperature and improving the optical system performance are proved effective. Numerical optimization of the cooling circuit and simulation of the aperture are performed , and the factors affect the optical system performance in the mean time are also investigated.

  18. Influence of localized surface plasmons on Pauli blocking and optical limiting in graphene under femtosecond pumping

    Science.gov (United States)

    Bongu, Sudhakara Reddy; Bisht, Prem B.; Namboodiri, Raman C. K.; Nayak, Pranati; Ramaprabhu, Sundara; Kelly, Thomas J.; Fallon, Colm; Costello, John T.

    2014-08-01

    The Pauli blocking limit and optical limiting threshold have been found to be modified following silver-nanoparticle decoration of functionalized hydrogen induced exfoliated graphene. Femtosecond Z-scan experiments have been used to measure the Pauli blocking range, optical limiting threshold, and the third order nonlinear susceptibility (χ(3)) values. The observed results have been explained by modified band structure of graphene in the presence of silver nanoparticles and their localized surface plasmon resonances.

  19. Asymmetric Gain-Saturated Spectrum in One-pump Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Rottwitt, Karsten; Galili, Michael

    2011-01-01

    The effect of third-order dispersion on the saturated-gain in fiber optical parametric amplifiers is experimentally demonstrated. A possible interpretation in terms of dispersive waves, which change the power transfer to the signal, is presented.......The effect of third-order dispersion on the saturated-gain in fiber optical parametric amplifiers is experimentally demonstrated. A possible interpretation in terms of dispersive waves, which change the power transfer to the signal, is presented....

  20. Design of a stacked diode array pumped Nd:YAG laser with a truncated compound parabolic concentrator and a diffusive optical cavity

    CERN Document Server

    Lee, S M; Yun, M J; Cha, B H; Lee, J M

    1999-01-01

    We designed and analyzed a new Nd:YAG laser which employs a combination of a truncated compound parabolic concentrator (CPC) and a diffusive optical pump cavity for pumping with a stacked diode array. A design code based on a ray-tracing algorithm was developed to analyze the Nd:YAG laser system. The optimum truncated CPC profile was determined from analyses of the dependences of the pump-beam distribution and the total absorbed power in the laser crystal upon the acceptance angle and the slit width of the CPC. In addition, the analyses show the importance of the acceptance angle in designing an efficient laser system with a truncated CPC. Using conservative design parameters, the design code predicted a Nd:YAG laser output of 130 W with a corresponding optical slope efficiency of 44%.

  1. Efficient optical pumping and high optical depth in a hollow-core photonic-crystal fibre for a broadband quantum memory

    Science.gov (United States)

    Sprague, Michael R.; England, Duncan G.; Abdolvand, Amir; Nunn, Joshua; Jin, Xian-Min; Kolthammer, W. Steven; Barbieri, Marco; Rigal, Bruno; Michelberger, Patrick S.; Champion, Tessa F. M.; Russell, Philip St. J.; Walmsley, Ian A.

    2013-05-01

    The generation of large multiphoton quantum states—for applications in computing, metrology and simulation—requires a network of high-efficiency quantum memories capable of storing broadband pulses. Integrating these memories into a fibre offers a number of advantages towards realizing this goal: strong light-matter coupling at low powers, simplified alignment and compatibility with existing photonic architectures. Here, we introduce a large-core kagome-structured hollow-core fibre as a suitable platform for an integrated fibre-based quantum memory with a warm atomic vapour. We demonstrate, for the first time, efficient optical pumping in such a system, where 90 ± 1% of atoms are prepared in the ground state. We measure high optical depths (3 × 104) and narrow homogeneous linewidths (6 ± 2 MHz) that do not exhibit significant transit-time broadening, showing that we can prepare a Λ-level system in a pure state. Our results establish that kagome fibres are suitable for implementing a broadband, room-temperature quantum memory, as well as a range of nonlinear optical effects.

  2. Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation)

    Science.gov (United States)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2017-03-01

    Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

  3. Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

    2017-06-01

    In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

  4. All-optical wavelength multicasting with extinction ratio enhancement using pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber

    DEFF Research Database (Denmark)

    Chow, K.K.; Shu, Chester; Lin, Chinlon;

    2006-01-01

    All optical wavelength multicasting at 4 x 10 Gb/s with extinction ratio enhancement has been demonstrated based on pump-modulated four-wave mixing in a nonlinear photonic crystal fiber. We show that the input signal wavelength can simultaneously convert to four different wavelengths, with a power...

  5. One-Watt level mid-IR output, singly resonant, continuous-wave optical parametric oscillator pumped by a monolithic diode laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; Sumpf, Bernd; van der Slot, Petrus J.M.; Erbert, Götz; Boller, Klaus J.

    2010-01-01

    We report more than 1.1 Watt of idler power at 3373 nm in a singly resonant optical parametric oscillator (SRO), directly pumped by a single-frequency monolithic tapered diode laser. The SRO is based on a periodically poled MgO:LiNbO3 crystal in a four mirror cavity and is excited by 8.05 W of 1062

  6. Far-infrared laser action in vinyl chloride, vinyl bromide, and vinyl fluoride optically pumped by a CW N2O laser

    Science.gov (United States)

    Gastaud, C.; Redon, M.; Belland, P.; Fourrier, M.

    1984-06-01

    This paper reports the first use of a N2O laser for optically pumping vinyl halides, to obtain new cw submillimeter laser lines. Eighteen far-infrared (FIR) emissions have been observed in vinyl chloride, twenty five in vinyl bromide and thirty eight in vinyl flouride.

  7. Coherent combining of fiber-laser-pumped frequency converters using all fiber electro-optic modulator for active phase control

    Science.gov (United States)

    Bourdon, P.; Durécu, A.; Canat, G.; Le Gouët, J.; Goular, D.; Lombard, L.

    2015-03-01

    Coherent beam combining (CBC) by active phase control could be useful for power scaling fiber-laser-pumped optical frequency converters like OPOs. However, a phase modulator operating at the frequency-converted wavelength is needed, which is non standard component. Fortunately, nonlinear conversion processes rely on a phase-matching condition correlating, not only the wave vectors of the coupled waves, but also their phases. This paper demonstrates that, using this phase correlation for indirect control of the phase, coherent combining of optical frequency converters is feasible using standard all-fibered electro-optic modulators. For the sake of demonstration, this new technique is experimentally applied twice for continuous wave second-harmonic-generator (SHG) combination: i) combining 2 SHG of 1.55-μm erbium-doped fiber amplifiers in PPLN crystals generating 775-nm beams; ii) combining 2 SHG of 1.064-μm ytterbium-doped fiber amplifiers in LBO crystals generating 532-nm beams. Excellent CBC efficiency is achieved on the harmonic waves in both these experiments, with λ/20 and λ/30 residual phase error respectively. In the second experiment, I/Q phase detection is added on fundamental and harmonic waves to measure their phase variations simultaneously. These measurements confirm the theoretical expectations and formulae of correlation between the phases of the fundamental and harmonic waves. Unexpectedly, in both experiments, when harmonic waves are phase-locked, a residual phase difference remains between the fundamen tal waves. Measurements of the spectrum of these residual phase differences locate them above 50 Hz, revealing that they most probably originate in fast-varying optical path differences induced by turbulence and acoustic-waves on the experimental breadboard.

  8. Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers

    Science.gov (United States)

    Stefanov, Ivan L.; Hadjichristov, Georgi B.

    2012-03-01

    Optical interferometric technique is applied to characterize the nonlocal response of optically transparent ion implanted polymers. The thermal nonlinearity of the ion-modified material in the near-surface region is induced by continuous wave (cw) laser irradiation at a relatively low intensity. The interferometry approach is demonstrated for a subsurface layer of a thickness of about 100 nm formed in bulk polymethylmethacrylate (PMMA) by implantation with silicon ions at an energy of 50 keV and fluence in the range 1014-1017 cm-2. The laser-induced thermooptic effect in this layer is finely probed by interferometric imaging. The interference phase distribution in the plane of the ion implanted layer is indicative for the thermal nonlinearity of the near-surface region of ion implanted optically transparent polymeric materials.

  9. Binding energies of trions and biexcitons in two-dimensional semiconductors from diffusion quantum Monte Carlo calculations

    Science.gov (United States)

    Szyniszewski, M.; Mostaani, E.; Drummond, N. D.; Fal'ko, V. I.

    2017-02-01

    Excitonic effects play a particularly important role in the optoelectronic behavior of two-dimensional (2D) semiconductors. To facilitate the interpretation of experimental photoabsorption and photoluminescence spectra we provide statistically exact diffusion quantum Monte Carlo binding-energy data for Mott-Wannier models of excitons, trions, and biexcitons in 2D semiconductors. We also provide contact pair densities to allow a description of contact (exchange) interactions between charge carriers using first-order perturbation theory. Our data indicate that the binding energy of a trion is generally larger than that of a biexciton in 2D semiconductors. We provide interpolation formulas giving the binding energy and contact density of 2D semiconductors as functions of the electron and hole effective masses and the in-plane polarizability.

  10. Amplitude regeneration of RZ-DPSK signals in single-pump fiber-optic parametric amplifiers

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Lorenzen, Michael Rodas; Seoane, Jorge

    2009-01-01

    to demonstrate amplitude regeneration of a distorted RZ-DPSK signal in a gain-saturated FOPA. An optical signal-to-noise ratio penalty of 3.5 dB after amplitude distortion is shown to be reduced to 0.2 dB after the FOPA, thus clearly demonstrating the regenerative nature of saturated FOPAs for RZ-DPSK modulation....

  11. Investigation of two-beam-pumped noncollinear optical parametric chirped-pulse amplification for the generation of few-cycle light pulses.

    Science.gov (United States)

    Herrmann, Daniel; Tautz, Raphael; Tavella, Franz; Krausz, Ferenc; Veisz, Laszlo

    2010-03-01

    We demonstrate a new and compact Phi-plane-pumped noncollinear optical parametric chirped-pulse amplification (NOPCPA) scheme for broadband pulse amplification, which is based on two-beam-pumping (TBP) at 532 nm. We employ type-I phase-matching in a 5 mm long BBO crystal with moderate pump intensities to preserve the temporal pulse contrast. Amplification and compression of the signal pulse from 675 nm - 970 nm is demonstrated, which results in the generation of 7.1-fs light pulses containing 0.35 mJ energy. In this context, we investigate the pump-to-signal energy conversion efficiency for TBP-NOPCPA and outline details for few-cycle pulse characterization. Furthermore, it is verified, that the interference at the intersection of the two pump beams does not degrade the signal beam spatial profile. It is theoretically shown that the accumulated OPA phase partially compensates for wave-vector mismatch and leads to extended broadband amplification. The experimental outcome is supported by numerical split-step simulations of the parametric signal gain, including pump depletion and parametric fluorescence.

  12. Performance assessment of a new laser system for efficient spin exchange optical pumping in a spin maser measurement of {sup 129}Xe EDM

    Energy Technology Data Exchange (ETDEWEB)

    Funayama, C., E-mail: funayama@yap.nucl.ap.titech.ac.jp [Tokyo Institute of Technology, Department of Physics (Japan); Furukawa, T. [Tokyo Metropolitan University, Department of Physics (Japan); Sato, T.; Ichikawa, Y.; Ohtomo, Y.; Sakamoto, Y.; Kojima, S.; Suzuki, T.; Hirao, C.; Chikamori, M.; Hikota, E.; Tsuchiya, M. [Tokyo Institute of Technology, Department of Physics (Japan); Yoshimi, A. [Okayama University, Research Core for Extreme Quantum World (Japan); Bidinosti, C. P. [University of Winnipeg, Department of Physics (Canada); Ino, T. [Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK) (Japan); Ueno, H. [RIKEN Nishina Center, RIKEN (Japan); Matsuo, Y. [Hosei University, Department of Advanced Sciences (Japan); Fukuyama, T. [Osaka University, Research Center for Nuclear Physics (RCNP) (Japan); Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan)

    2015-11-15

    We demonstrate spin-exchange optical pumping of {sup 129}Xe atoms with our newly made laser system. The new laser system was prepared to provide higher laser power required for the stable operation of spin maser oscillations in the {sup 129}Xe EDM experiment. We studied the optimum cell temperature and pumping laser power to improve the degree of {sup 129}Xe spin polarization. The best performance was achieved at the cell temperature of 100 {sup ∘}C with the presently available laser power of 1 W. The results show that a more intense laser is required for further improvement of the spin polarization at higher cell temperatures in our experiment.

  13. Efficient optical pumping and high optical depth in a hollow-core photonic-crystal fibre for a broadband quantum memory

    CERN Document Server

    Sprague, Michael R; Abdolvand, Amir; Nunn, Joshua; Jin, Xian-Min; Kolthammer, W Steven; Barbieri, Marco; Rigal, Bruno; Michelberger, Patrick S; Champion, Tessa F M; Russell, Philip St J; Walmsley, Ian A

    2012-01-01

    The generation of large multiphoton quantum states - for applications in computing, metrology, and simulation - requires a network of high-efficiency quantum memories capable of storing broadband pulses. Integrating these memories into a fibre offers a number of advantages towards realising this goal: strong light-matter coupling at low powers, simplified alignment, and compatibility with existing photonic architectures. Here, we introduce a large-core kagome-structured hollow-core fibre as a suitable platform for an integrated fibre-based quantum memory with a warm atomic vapour. We demonstrate, for the first time, efficient optical pumping in a hollow-core photonic-crystal fibre with a warm atomic vapour, where (90 $\\pm$ 1)% of atoms are prepared in the ground state. We measure high optical depths (3$\\times 10^{4}$) and, also, narrow homogeneous linewidths that do not exhibit significant transit-time broadening. Our results establish that kagome fibres are suitable for implementing a broadband, room-tempera...

  14. Optically Pumped Atomic Rubidium Lasers: Two-Photon and Exciplex Excitation Mechanisms

    Science.gov (United States)

    2013-06-01

    atomic oxygen”. Physical Review A, 34(1):185–198, 1986. 21. D. Touahri, A. Clairon J. Zondy R. Felder -L. Hilico B. de Beauvoir F. Biraben, O. Acef and F...979, 2004. 24. F. Nez, R. Felder , F. Biraben and Y. Millerioux. “Optical frequency determina- tion of the hyperfine components of the 5S1/2 − 5D3/2

  15. Optical afterburner for an x-ray free electron laser as a tool for pump-probe experiments

    Directory of Open Access Journals (Sweden)

    E. L. Saldin

    2010-03-01

    Full Text Available We propose a new scheme for two-color operation of an x-ray self-amplified spontaneous emission free electron laser (SASE FEL. The scheme is based on an intrinsic feature of such a device: chaotic modulations of electron beam energy and energy spread on the scale of FEL coherence length are converted into large density modulations on the same scale with the help of a dispersion section, installed behind the x-ray undulator. Powerful radiation is then generated with the help of a dedicated radiator (like an undulator that selects a narrow spectral line, or one can simply use, for instance, broadband edge radiation. A typical radiation wavelength can be as short as a FEL coherence length, and can be redshifted by increasing the dispersion section strength. In practice it means the wavelength ranges from vacuum ultraviolet to infrared. The long-wavelength radiation pulse is naturally synchronized with the x-ray pulse and can be either directly used in pump-probe experiments or cross correlated with a high-power pulse from a conventional laser system. In this way experimenters overcome jitter problems and can perform pump-probe experiments with femtosecond resolution. Additional possibilities like on-line monitoring of x-ray pulse duration (making “optical replica” of an x-ray pulse are also discussed in the paper. The proposed scheme is very simple, cheap, and robust, and therefore can be easily realized in facilities like FLASH, European XFEL, LCLS, and SCSS.

  16. Optically pumped alkali laser and amplifier using helium-3 buffer gas

    Science.gov (United States)

    Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan

    2010-09-28

    In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.

  17. Intracavity optical parametric oscillator at 1.5-7-μm wavelength pumped by passive Q-switched Nd:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Mingwei Gao; Chunqing Gao; Kun Tang; Zhifeng Lin; Xiuyong Zhang

    2008-01-01

    A high-repetition-rate eye-safe optical parametric oscillator(OPO),using a non-critically phase-matched KTP crystal intracavity pumped by a passively Q-switched Nd:GdVO4/Cr4+:YAG laser,is experimentally demonstrated.The conversion efficiency for the average power is 7% from pump diode input to OPO signal output and the slope efficiency is up to 10.3%.With an incident pump power of 7.3 W.the compact intracavity OPO(IOPO)cavity,operating at 15 kHz,produces an average power of 0.57 W at 1570 nm with a pulse width as short as 6 ns.The peak power at 1570 nm is higher than 6.3 kW.

  18. Phase transitions in ensembles of solitons induced by an optical pumping or a strong electric field

    Science.gov (United States)

    Karpov, P.; Brazovskii, S.

    2016-09-01

    The latest trend in studies of modern electronically and/or optically active materials is to provoke phase transformations induced by high electric fields or by short (femtosecond) powerful optical pulses. The systems of choice are cooperative electronic states whose broken symmetries give rise to topological defects. For typical quasi-one-dimensional architectures, those are the microscopic solitons taking from electrons the major roles as carriers of charge or spin. Because of the long-range ordering, the solitons experience unusual super-long-range forces leading to a sequence of phase transitions in their ensembles: the higher-temperature transition of the confinement and the lower one of aggregation into macroscopic walls. Here we present results of an extensive numerical modeling for ensembles of both neutral and charged solitons in both two- and three-dimensional systems. We suggest a specific Monte Carlo algorithm preserving the number of solitons, which substantially facilitates the calculations, allows to extend them to the three-dimensional case and to include the important long-range Coulomb interactions. The results confirm the first confinement transition, except for a very strong Coulomb repulsion, and demonstrate a pattern formation at the second transition of aggregation.

  19. Theoretical simulations of protective thin film Fabry-Pérot filters for integrated optical elements of diode pumped alkali lasers (DPAL

    Directory of Open Access Journals (Sweden)

    L. Quarrie

    2014-09-01

    Full Text Available The lifetime of Diode-Pumped Alkali Lasers (DPALs is limited by damage initiated by reaction of the glass envelope of its gain medium with rubidium vapor. Rubidium is absorbed into the glass and the rubidium cations diffuse through the glass structure, breaking bridging Si-O bonds. A damage-resistant thin film was developed enhancing high-optical transmission at natural rubidium resonance input and output laser beam wavelengths of 780 nm and 795 nm, while protecting the optical windows of the gain cell in a DPAL. The methodology developed here can be readily modified for simulation of expected transmission performance at input pump and output laser wavelengths using different combination of thin film materials in a DPAL. High coupling efficiency of the light through the gas cell was accomplished by matching the air-glass and glass-gas interfaces at the appropriate wavelengths using a dielectric stack of high and low index of refraction materials selected to work at the laser energies and protected from the alkali metal vapor in the gain cell. Thin films as oxides of aluminum, zirconium, tantalum, and silicon were selected allowing the creation of Fabry-Perot optical filters on the optical windows achieving close to 100% laser transmission in a solid optic combination of window and highly reflective mirror. This approach allows for the development of a new whole solid optic laser.

  20. Theoretical simulations of protective thin film Fabry-Pérot filters for integrated optical elements of diode pumped alkali lasers (DPAL)

    Science.gov (United States)

    Quarrie, L.

    2014-09-01

    The lifetime of Diode-Pumped Alkali Lasers (DPALs) is limited by damage initiated by reaction of the glass envelope of its gain medium with rubidium vapor. Rubidium is absorbed into the glass and the rubidium cations diffuse through the glass structure, breaking bridging Si-O bonds. A damage-resistant thin film was developed enhancing high-optical transmission at natural rubidium resonance input and output laser beam wavelengths of 780 nm and 795 nm, while protecting the optical windows of the gain cell in a DPAL. The methodology developed here can be readily modified for simulation of expected transmission performance at input pump and output laser wavelengths using different combination of thin film materials in a DPAL. High coupling efficiency of the light through the gas cell was accomplished by matching the air-glass and glass-gas interfaces at the appropriate wavelengths using a dielectric stack of high and low index of refraction materials selected to work at the laser energies and protected from the alkali metal vapor in the gain cell. Thin films as oxides of aluminum, zirconium, tantalum, and silicon were selected allowing the creation of Fabry-Perot optical filters on the optical windows achieving close to 100% laser transmission in a solid optic combination of window and highly reflective mirror. This approach allows for the development of a new whole solid optic laser.

  1. Theoretical simulations of protective thin film Fabry-Pérot filters for integrated optical elements of diode pumped alkali lasers (DPAL)

    Energy Technology Data Exchange (ETDEWEB)

    Quarrie, L., E-mail: Lindsay.Quarrie@l-3com.com, E-mail: lindsay.o.quarrie@gmail.com [New Mexico Institute of Mining and Technology, Department of Materials Engineering, 801 LeRoy Place, Socorro, NM 87801 (United States); Air Force Research Laboratory, AFRL/RDLC Laser CoE, 3550 Aberdeen Avenue SE, Kirtland AFB, NM 87117-5776 (United States)

    2014-09-15

    The lifetime of Diode-Pumped Alkali Lasers (DPALs) is limited by damage initiated by reaction of the glass envelope of its gain medium with rubidium vapor. Rubidium is absorbed into the glass and the rubidium cations diffuse through the glass structure, breaking bridging Si-O bonds. A damage-resistant thin film was developed enhancing high-optical transmission at natural rubidium resonance input and output laser beam wavelengths of 780 nm and 795 nm, while protecting the optical windows of the gain cell in a DPAL. The methodology developed here can be readily modified for simulation of expected transmission performance at input pump and output laser wavelengths using different combination of thin film materials in a DPAL. High coupling efficiency of the light through the gas cell was accomplished by matching the air-glass and glass-gas interfaces at the appropriate wavelengths using a dielectric stack of high and low index of refraction materials selected to work at the laser energies and protected from the alkali metal vapor in the gain cell. Thin films as oxides of aluminum, zirconium, tantalum, and silicon were selected allowing the creation of Fabry-Perot optical filters on the optical windows achieving close to 100% laser transmission in a solid optic combination of window and highly reflective mirror. This approach allows for the development of a new whole solid optic laser.

  2. Measurements of nonlinear lensing in a semiconductor disk laser gain sample under optical pumping and using a resonant femtosecond probe laser

    Science.gov (United States)

    Quarterman, A. H.; Mirkhanov, S.; Smyth, C. J. C.; Wilcox, K. G.

    2016-09-01

    Accurate characterizations of the nonlinear refractive index of semiconductor disk laser (SDL) gain samples are of critical importance for understanding the behavior of self-mode-locked SDLs. Here we describe measurements of nonlinear lensing in an SDL gain sample for a wide range of optical pump intensities and using a probe which is on resonance with the quantum wells in the SDL gain sample and whose intensity, pulse duration, and spot size are chosen to be similar to those reported in self-mode-locked SDLs. Under these conditions, we determine an effective value of the nonlinear refractive index, n2 = -6.5 × 10-13 cm2/W at zero pump intensity, and find that the value of n2 changes by less than 25% over the range of pump intensities studied. The nonlinear refractive index is measured using a variation on the well-established z-scan technique, which was modified to make it better suited to the measurement of optically pumped samples.

  3. A Bloch equation approach to intensity dependent optical spectra of light harvesting complex II: excitation dependence of light harvesting complex II pump-probe spectra.

    Science.gov (United States)

    Richter, Marten; Renger, Thomas; Knorr, Andreas

    2008-01-01

    On the basis of the recent progress in the resolution of the structure of the antenna light harvesting complex II (LHC II) of the photosystem II, we propose a microscopically motivated theory to predict excitation intensity-dependent spectra. We show that optical Bloch equations provide the means to include all 2( N ) excited states of an oligomer complex of N coupled two-level systems and analyze the effects of Pauli Blocking and exciton-exciton annihilation on pump-probe spectra. We use LHC Bloch equations for 14 Coulomb coupled two-level systems, which describe the S (0) and S (1) level of every chlorophyll molecule. All parameter introduced into the Hamiltonian are based on microscopic structure and a quantum chemical model. The derived Bloch equations describe not only linear absorption but also the intensity dependence of optical spectra in a regime where the interplay of Pauli Blocking effects as well as exciton-exciton annihilation effects are important. As an example, pump-probe spectra are discussed. The observed saturation of the spectra for high intensities can be viewed as a relaxation channel blockade on short time scales due to Pauli blocking. The theoretical investigation is useful for the interpretation of the experimental data, if the experimental conditions exceed the low intensity pump limit and effects like strong Pauli Blocking and exciton-exciton annihilation need to be considered. These effects become important when multiple excitations are generated by the pump pulse in the complex.

  4. High-sensitivity operation of single-beam optically pumped magnetometer in a kHz frequency range

    Science.gov (United States)

    Savukov, I.; Kim, Y. J.; Shah, V.; Boshier, M. G.

    2017-03-01

    Optically pumped magnetometers (OPM) can be used in various applications, from magnetoencephalography to magnetic resonance imaging and nuclear quadrupole resonance (NQR). OPMs provide high sensitivity and have the significant advantage of non-cryogenic operation. To date, many magnetometers have been demonstrated with sensitivity close to 1 fT, but most devices are not commercialized. Most recently, QuSpin developed a model of OPM that is low cost, high sensitivity, and convenient for users, which operates in a single-beam configuration. Here we developed a theory of single-beam (or parallel two-beam) magnetometers and showed that it is possible to achieve good sensitivity beyond their usual frequency range by tuning the magnetic field. Experimentally we have tested and optimized a QuSpin OPM for operation in the frequency range from DC to 1.7 kHz, and found that the performance was only slightly inferior despite the expected decrease due to deviation from the spin-exchange relaxation-free regime.

  5. An actively Q-switched single-longitudinal-mode fiber laser with an optically pumped saturable absorber

    Science.gov (United States)

    Yun, Hyo-Geun; Lee, Seoung Hun; Lee, Min Hee; Kim, Kyong Hon

    2013-09-01

    We have demonstrated an actively Q-switched single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser by using an EDF saturable absorber modulated under an external laser pulse injection. A laser output of 1531.9 nm wavelength from a distributed-feedback laser diode was amplified with an EDF amplifier and modulated with an external electro-optical modulator, and the modulated signals were used as control pulses to saturate the EDF saturable absorber for the actively Q-switched ring-type fiber laser operation. Actively Q-switched 1542 nm wavelength laser pulses of 4.5 nJ pulse energy and of 4.0μs pulse width were achieved at a repetition rate of 100 Hz. When the Q-switched laser pulse energy was reduced to about 0.54 nJ by decreasing the gain-pump power used for exciting the ring cavity and the control-pulse beam power used for bleaching out the saturable absorber, the SLM laser pulses were achieved. Further improvement of the Q-switched SLM laser pulse output can be achieved simply by using an external laser amplifier and by shortening the cavity length with short pigtailed-fiber laser components, and thus the SLM laser pulses can be useful for various applications.

  6. A fiber laser pumped dual-wavelength mid-infrared laser based on optical parametric oscillation and intracavity difference frequency generation

    Science.gov (United States)

    Wang, Peng; Shang, Yaping; Li, Xiao; Shen, Meili; Xu, Xiaojun

    2017-02-01

    We report a dual-wavelength mid-infrared laser based on intracavity difference frequency generation (DFG) in an MgO-doped periodically poled LiNbO3, which was pumped by a dual-wavelength fiber MOPA consisting of two parts: a dual-wavelength seed and a power amplifier. The maximum pump power was 74.1 W and the wavelengths were 1060 nm and 1090 nm. The wavelengths of the mid-infrared output were 3.1 µm and 3.4 µm under maximum pump power with a total idler power of 6.57 W. The corresponding pump-to-idler slope efficiency reached 12%. The contrast for the peak intensity of the emissions for the two idlers was 0.6. A power preamplifier was added in a further experiment to enhance the contrast. The idler output reached 4.45 W under the maximum pump power of 70 W, which was lower than before. However, the contrast for the idler emission peak intensity was increased to 1.18. The signal wave generated in the experiment only had a single wavelength around 1.6 µm, indicating that two kinds of nonlinear processes occurred in the experiment, namely optical parametric oscillation and intracavity DFG.

  7. Short pulse diode-pumped Tm:YAG slab laser electro-optically Q-switched by RbTiOPO4 crystal

    Science.gov (United States)

    Jin, Lin; Liu, Pian; Huang, Haitao; Liu, Xuan; Shen, Deyuan

    2016-10-01

    In this paper, a laser diode end pumped RbTiOPO4 (RTP) electro-optically Q-switched Tm:YAG slab laser was demonstrated. Stable Q-switched pulse with the shortest pulse width of 58 ns and an average output power of 7.5 W were realized at the repetition rate of 1 KHz, corresponding to the slope efficiency of 21.7%.

  8. Adjusting the properties of the photon generated via an optical parametric oscillator by using a pulse pumped laser

    Institute of Scientific and Technical Information of China (English)

    Chen Song; Shi Bao-Sen; Guo Guang-Can

    2011-01-01

    The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric downconversion almost always utilize continuous wave pump light,but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump,which limits its application in the quantum information realm.However,a pulse pump can help to solve this problem.In this paper,we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric downconversion in detail and show how the pump pulse affects the multi-photon interference visibility,two-photon waveform,joint spectrum and spectral brightness.

  9. Development of an ultra-widely tunable DFG-THz source with switching between organic nonlinear crystals pumped with a dual-wavelength BBO optical parametric oscillator.

    Science.gov (United States)

    Notake, Takashi; Nawata, Kouji; Kawamata, Hiroshi; Matsukawa, Takeshi; Qi, Feng; Minamide, Hiroaki

    2012-11-01

    We developed a difference frequency generation (DFG) source with an organic nonlinear optical crystal of DAST or BNA selectively excited by a dual-wavelength β-BaB(2)O(4) optical parametric oscillator (BBO-OPO). The dual-wavelength BBO-OPO can independently oscillate two lights with different wavelengths from 800 to 1800 nm in a cavity. THz-wave generation by using each organic crystal covers ultrawide range from 1 to 30 THz with inherent intensity dips by crystal absorption modes. The reduced outputs can be improved by switching over the crystals with adequately tuned pump wavelengths of the BBO-OPO.

  10. Optical Dynamic Analysis of Thrombus Inside a Centrifugal Blood Pump During Extracorporeal Mechanical Circulatory Support in a Porcine Model.

    Science.gov (United States)

    Fujiwara, Tatsuki; Sakota, Daisuke; Ohuchi, Katsuhiro; Endo, Shu; Tahara, Tomoki; Murashige, Tomotaka; Kosaka, Ryo; Oi, Keiji; Mizuno, Tomohiro; Maruyama, Osamu; Arai, Hirokuni

    2017-03-20

    Complications due to pump thrombus remain the weak point of mechanical circulatory support (MCS), such as the use of a left ventricular assist device (LVAD) or extracorporeal membrane oxygenation, leading to poor outcomes. Hyperspectral imaging (HSI) is an effective imaging method using a hyperspectral (HS) camera, which comprises a spectrophotometer and a charge-coupled device camera to discriminate thrombus from whole blood. Animal experiments were conducted to analyze dynamic imaging of thrombus inside a prototype of a hydrodynamically levitated centrifugal blood pump using an HSI system. Six pigs were divided into a venous circulation group (n = 3) and an arterial circulation group (n = 3). Inflow and outflow cannulae were inserted into the jugular veins in the venous circulation group. The latter simulated an LVAD application. To create thrombogenic conditions, pump flow was maintained at 1 L/min without anticoagulation. An image of the bottom surface of the pump was captured by the HS camera every 4 nm over the wavelength range of 608-752 nm. Real-time dynamic images of the inside of the pump were displayed on the monitor. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment. This imaging system also succeeded in determining the origins of pump thrombus: from inside the pump in two cases, and from outside in four cases. Two main possible sources of pump thrombus originating outside the pump were identified on autopsy: wedge thrombus around the inflow cannula; and string-like thrombus at the junction between the pump inlet and circuit tube. The results of this study from close observation of the changing appearance of pump thrombus may contribute to improvements in the safety of extracorporeal MCS.

  11. Optically pumped laser lines of Na2 pumped by Kr/+/ /6471 A/ and HeNe /6328 A/ lasers - Identification of old lines and prediction of possible new lines

    Science.gov (United States)

    Verma, K. K.; Stwalley, W. C.; Zemke, W. T.

    1981-01-01

    The laser emission lines of a sodium dimer laser pumped by Kr(+) and HeNe lasers at wavelengths of 6471 and 6328 A, respectively, are identified. The Na2 fluorescence was excited in a crossed heat pipe oven at a sodium pressure of about 1 torr, and recorded spectra were compared with transition probability calculations. For the 6471-A pump, three series excited by absorption through the transitions v-prime = 13, J-prime = 35 - v-double prime = 4, J-double prime = 34; v-prime = 13, J-prime = 83 - v-double-prime = 2, J-double prime = 84 and v-prime = 20, J-prime = 98 - v-double prime = 6, J-double prime = 99 are observed in the region 6100-8350 A. At 6328 A, series excited through the transitions v-prime = 14, J-prime = 45 - v-double prime = 2, J-double prime = 46; v-prime = 16, J-prime = 17 - v-double prime = 4, J-double prime = 18; v-prime = 22, J-prime = 86 - v-double prime = 6, J-double prime = 85 and v-prime = 25, J-prime = 87 - v-double prime = 8, J-double prime = 86. Most of the previously observed optically pumped lines are found to correspond to the three level laser system. Additional wavelengths expected to undergo lasing under slightly improved conditions are also identified.

  12. Effect of morphology on spectral properties of magneto-trion X{sup +} in vertically coupled type II quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Horta-Piñeres, Sindi, E-mail: sdhorta@yahoo.es [Group of Investigation in Condensed Matter Theory, Universidad del Magdalena, Santa Marta (Colombia); Universidad de Sucre, Sincelejo (Colombia); Elizabeth Escorcia-Salas, G., E-mail: elizabethescorcia@gmail.com [Group of Investigation in Condensed Matter Theory, Universidad del Magdalena, Santa Marta (Colombia); Mikhailov, I.D., E-mail: mikhail2811@gmail.com [Universidad Industrial de Santander, Apartado Aereo 678, Bucaramanga (Colombia); Sierra-Ortega, J., E-mail: jsierraortega@gmail.com [Group of Investigation in Condensed Matter Theory, Universidad del Magdalena, Santa Marta (Colombia)

    2014-11-15

    The energy spectrum of a positively charged exciton confined in vertically coupled type II quantum dots with different morphologies in the presence of the external magnetic field is studied. The effect of the quantum dot morphology on the curves of the lowest energy levels as functions of the magnetic field is analyzed. It is shown that a strong correlation presented in this system generates the Aharonov–Bohm oscillations of the lower energy levels similar to those in wide quantum ring. The novel curves of the trion energies dependences on the external magnetic field for the disk-like, lens-like, and cone-like structures are presented.

  13. Nonlinear resonances caused by coherent, optical pumping and saturating effects in the presence of three laser fields for the 85Rb-D2 line

    Science.gov (United States)

    Hossain, M. M.; Mitra, S.; Poddar, P.; Chaudhuri, C.; Ray, B.; Ghosh, P. N.

    2011-06-01

    Atomic coherence resonances such as electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) signals are observed in a Doppler broadened multi-level system for the D2 line of 85Rb atoms in a vapour cell considering different types of atom-laser coupling schemes. Besides the coherence resonances, the nonlinear resonances like velocity selective optical pumping (VSOP) dips and velocity selective resonances (VSR) are also observed for the non-zero velocity selective groups of atoms. In the presence of pump, control and probe laser fields, we observe two EIT signals in a double Λ-type system and two EIA signals in a double V-type system. We are able to see the EIA signal for the non-zero velocity group of atoms when the pump laser is locked with an open transition by a small red detuning. We also report the experimental observation of simultaneous EIT and EIA signals in a (Λ+V)-type system. The effect of frequency tuning of the control laser is also studied in the presence of the frequency locked pump laser. A simple theoretical analysis explains the experimental results.

  14. Nonlinear resonances caused by coherent, optical pumping and saturating effects in the presence of three laser fields for the {sup 85}Rb-D{sub 2} line

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, M M; Mitra, S; Poddar, P; Chaudhuri, C; Ray, B [Department of Physics, University of Calcutta, 92 A P C Road, Kolkata 700 009 (India); Ghosh, P N, E-mail: brphy@caluniv.ac.in [Jadavpur University, 188 Raja S C Mallik Road, Kolkata 700 032 (India)

    2011-06-14

    Atomic coherence resonances such as electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) signals are observed in a Doppler broadened multi-level system for the D{sub 2} line of {sup 85}Rb atoms in a vapour cell considering different types of atom-laser coupling schemes. Besides the coherence resonances, the nonlinear resonances like velocity selective optical pumping (VSOP) dips and velocity selective resonances (VSR) are also observed for the non-zero velocity selective groups of atoms. In the presence of pump, control and probe laser fields, we observe two EIT signals in a double {Lambda}-type system and two EIA signals in a double V-type system. We are able to see the EIA signal for the non-zero velocity group of atoms when the pump laser is locked with an open transition by a small red detuning. We also report the experimental observation of simultaneous EIT and EIA signals in a ({Lambda}+V)-type system. The effect of frequency tuning of the control laser is also studied in the presence of the frequency locked pump laser. A simple theoretical analysis explains the experimental results.

  15. Gain chip design, power scaling and intra-cavity frequency doubling with LBO of optically pumped red-emitting AlGaInP-VECSELs

    Science.gov (United States)

    Kahle, Hermann; Mateo, Cherry M. N.; Brauch, Uwe; Bek, Roman; Schwarzbäck, Thomas; Jetter, Michael; Graf, Thomas; Michler, Peter

    2016-03-01

    The wide range of applications in biophotonics, television or projectors, spectroscopy and lithography made the optically-pumped semiconductor (OPS) vertical external cavity surface-emitting lasers (VECSELs) an important category of power scalable lasers. The possibility of bandgap engineering, inserting frequency selective and converting elements into the open laser cavity and laser emission in the fundamental Gaussian mode leads to ongoing growth of the area of applications for tuneable laser sources. We present an AlGaInP-VECSEL system with a multi quantum well structure consisting of compressively strained GaInP quantum wells in an AlxGa1-xInP separate confinement heterostructure with an emission wavelength around 665 nm. The VECSEL chip with its n-λ cavity is pumped by a 532nm Nd:YAG laser under an angle to the normal incidence of 50°. In comparison, a gain chip design for high absorption values at pump wavelengths around 640nm with the use of quantum dot layers as active material is also presented. Frequency doubling is now realized with an antireflection coated lithium borate crystal, while a birefringent filter, placed inside the laser cavity under Brewster's angle, is used for frequency tuning. Further, power-scaling methods like in-well pumping as well as embedding the active region of a VECSEL between two transparent ic heaspreaders are under investigation.

  16. Particularities of optical pumping effects in cold and ultra-slow beams of Na and Cs in the case of cyclic transitions

    KAUST Repository

    Bruvelis, M.

    2015-12-09

    The time-dependent population dynamics of hyperfine (HF) levels of n2p3/2 states is examined for cyclic transitions in alkali atoms. We study a slow and cold atomic beam of Na (n = 3) and Cs (n = 6), taking into account the long interaction time of light with atoms (~200 μs) inside the resonant laser beam. Simple analytical expressions for the populations of the excited states and for the intensities of the absorption lines are derived for a three-level system model. We show that at moderate pump laser power the mixing of HF levels is sufficient to form a flow of population from a cyclic transition to partially open transitions. We discuss various phenomena associated with the evolution of optical pumping that cannot be explained by general analysis of two-level system model.

  17. High-power Femtosecond Optical Parametric Amplification at 1 kHz in BiB(3)O(6) pumped at 800 nm.

    Science.gov (United States)

    Petrov, Valentin; Noack, Frank; Tzankov, Pancho; Ghotbi, Masood; Ebrahim-Zadeh, Majid; Nikolov, Ivailo; Buchvarov, Ivan

    2007-01-22

    Substantial power scaling of a travelling-wave femtosecond optical parametric amplifier, pumped near 800 nm by a 1 kHz Ti:sapphire laser amplifier, is demonstrated using monoclinic BiB(3)O(6) in a two stage scheme with continuum seeding. Total energy output (signal plus idler) exceeding 1 mJ is achieved, corresponding to an intrinsic conversion efficiency of approximately 32% for the second stage. The tunability extends from 1.1 to 2.9 microm. The high parametric gain and broad amplification bandwidth of this crystal allowed the maintenance of the pump pulse duration, leading to pulse lengths less than 140 fs, both for the signal and idler pulses, even at such high output levels.

  18. Gain-switching dynamics in optically pumped single-mode InGaN vertical-cavity surface-emitting lasers.

    Science.gov (United States)

    Chen, Shaoqiang; Asahara, Akifumi; Ito, Takashi; Zhang, Jiangyong; Zhang, Baoping; Suemoto, Tohru; Yoshita, Masahiro; Akiyama, Hidefumi

    2014-02-24

    The gain-switching dynamics of single-mode pulses were studied in blue InGaN multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) through impulsive optical pumping. We measured the shortest single-mode pulses of 6.0 ps in width with a method of up-conversion, and also obtained the pulse width and the delay time as functions of pump powers from streak-camera measurements. Single-mode rate-equation calculations quantitatively and consistently explained the observed data. The calculations indicated that the pulse width in the present VCSELs was mostly limited by modal gain, and suggested that subpicosecond pulses should be possible within feasible device parameters.

  19. Photoluminescence spectra of an optically pumped erbium-doped micro-cavity with SiO{sub 2}/TiO{sub 2} distributed Bragg reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, Yann G., E-mail: boucher@enib.f [ENIB/RESO, CS 73862, F-29238 Brest cedex 3 (France); Chiasera, Alessandro, E-mail: achiaser@science.unitn.i [CNR-IFN, CSMFO, Via alla Cascata 56/C, I-38050 Povo (Trento) (Italy); Ferrari, Maurizio [CNR-IFN, CSMFO, Via alla Cascata 56/C, I-38050 Povo (Trento) (Italy); Righini, Giancarlo C., E-mail: direttore.dmd@cnr.i [CNR, Department of Materials and Devices, I-00185 Roma, and Nello Carrara Institute of Applied Physics, I-50019 Sesto Fiorentino (Florence) (Italy)

    2009-12-15

    We investigate the spectral properties of an optically pumped micro-cavity made of a half-wavelength erbium-doped SiO{sub 2} layer sandwiched between two six-period SiO{sub 2}/TiO{sub 2} distributed Bragg reflectors. The structure, grown by the rf-sputtering technique, is characterised by its transmittance and photoluminescence (PL) spectra. The pump laser operates at {lambda}{sub P}=514.5 nm under optimized oblique incidence. Extended (3x3) transfer matrix formalism including sources leads to an analytical description of the spectral and angular properties of the emitted field, for both states of polarization. As expected, a pronounced enhancement of the PL emission around the cavity resonance is observed.

  20. The analytical investigation of the super-Gaussian pump source on the thermal, stress and thermo-optics properties of double-clad Yb:glass fiber lasers

    Indian Academy of Sciences (India)

    H Nadgaran; P Elahi

    2005-07-01

    Fiber lasers have attracted considerable attention when their power can realistically be scaled to kilowatt level and beyond. In this paper, we assumed that the fiber core and first clad are exposed to a pump source with a super-Gaussian profile of order four. The effects of this non-uniform heat deposition on thermal, stress and thermo-optics properties such as temperature-dependent change of refractive index and thermally induced stress have been comprehensively studied and their equations analytically derived.

  1. Cr:ZnS laser-pumped subharmonic GaAs optical parametric oscillator with the spectrum spanning 3.6-5.6  μm.

    Science.gov (United States)

    Smolski, V O; Vasilyev, S; Schunemann, P G; Mirov, S B; Vodopyanov, K L

    2015-06-15

    Using a subharmonic optical parametric oscillator (OPO) based on orientation-patterned GaAs, we produced a broadband instantaneous output that spans 3.6-5.6 μm at 50-dB level (4.4-5.2 μm at 3 dB level), has 110 mW of average power, and is suitable for producing wideband-frequency combs in the mid-infrared. The OPO was synchronously pumped by a compact Kerr-lens mode-locked femtosecond Cr:ZnS oscillator with the central wavelength 2.38 μm and pulse repetition frequency 175 MHz.

  2. A compact spin-exchange optical pumping system for 3He polarization based on a solenoid coil, a VBG laser diode, and a cosine theta RF coil

    Science.gov (United States)

    Lee, Sungman; Kim, Jongyul; Moon, Myung Kook; Lee, Kye Hong; Lee, Seung Wook; Ino, Takashi; Skoy, Vadim R.; Lee, Manwoo; Kim, Guinyun

    2013-02-01

    For use as a neutron spin polarizer or analyzer in the neutron beam lines of the HANARO (High-flux Advanced Neutron Application ReactOr) nuclear research reactor, a 3He polarizer was designed based on both a compact solenoid coil and a VBG (volume Bragg grating) diode laser with a narrow spectral linewidth of 25 GHz. The nuclear magnetic resonance (NMR) signal was measured and analyzed using both a built-in cosine radio-frequency (RF) coil and a pick-up coil. Using a neutron transmission measurement, we estimated the polarization ratio of the 3He cell as 18% for an optical pumping time of 8 hours.

  3. Doppler-free approach to optical pumping dynamics in the $6S_{1/2}- 5D_{5/2}$ electric quadrupole transition of Cesium vapor

    CERN Document Server

    Chan, Eng Aik; Zheludev, Nikolay I; Wilkowski, David; Ducloy, Martial

    2016-01-01

    The $6S_{1/2}-5D_{5/2}$ electric quadrupole transition is investigated in Cesium vapor at room temperature via nonlinear Doppler-free 6P-6S-5D three-level spectroscopy. Frequency-resolved studies of individual E2 hyperfine lines allow one to analyze optical pumping dynamics, polarization selection rules and line intensities. It opens the way to studies of transfer of light orbital angular momentum to atoms, and the influence of metamaterials on E2 line spectra.

  4. Performance evaluation of ZnGeP2 optical parametric oscillator pumped by a Q-switched Tm,Ho:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Baoquan Yao; Youlun Ju; Yuezhu Wang; Wanjun He

    2008-01-01

    A doubly resonant ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumped by a novel Tm,Ho:GdVO4 laser was demonstrated. Cryogenic Tm(5 at.-%), Ho(0.5 at.-%):GdVO4 laser with high pulse repetition frequency (PRF) of 10 kHz at 2.05 μm was employed as pumping source of ZGP OPO. The 15-mm-long ZGP crystal, 55° cut for I-type phase-matching with low absorption coefficient less than 0.05 cm-1 at 2-μm, was placed in a plano-plano cavity with resonator length of 30 mm. The ZGP OPO generated a total combined output power of 1.2 W at 3.75 and 4.52 μm under pumping power of 5.3 W, corresponding to slope efficiency of 40% from incident 2-μm laser power to mid-infrared (Mid-IR) output. A widely tunable range from 3.0 to 6.5 μm was achieved by changing the crystal angle only 3.5 .

  5. The Effect of Phase-Shifting between Pumping and Signal Lights on Transmission Performance of Optical Fiber Communication Systems with in-Line PSA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper, the effect of phase-shifting between pumping light and input signal light in an optical Phase-Sensitive Amplifier (PSA) on dispersion compensation for optical fiber communication systems using PSA as in-line amplifiers is theoretically analyzed by computer simulation. From our simulation, we've got the result that the eye-pattern degradation of the high-speed signal increases rapidly with the accretion of fiber dispersion and also increases with the increasing of phase shift. But if the phase shift is controlled in a certain range, it won't affect the system performance. Otherwise, the system performance will be seriously degraded. At all events, the shifting range of PSA's phase, which shifts at both sides of zero, will be half of that which shifts at only one side.

  6. Thermal and pump power effect in SrMoO4:Er3+-Yb3+ phosphor for thermometry and optical heating

    Science.gov (United States)

    Soni, Abhishek Kumar; Rai, Vineet Kumar

    2017-01-01

    The pump power and temperature dependence study in the Er3+-Yb3+ codoped SrMoO4 phosphors for the green UC emission bands has been investigated by using two NIR (980 nm and 808 nm) laser radiation. The thermometric behaviour of the codoped phosphor operated in the 300-543 K gives maximum sensitivity ∼25.5 × 10-3 K-1 for 980 nm excitation whereas, for 808 nm excitation the maximum sensitivity is ∼21.5 × 10-3 K-1 over 300-465 K. The optical heating study upon two NIR laser radiations has also been performed. The experimental observations made in this article may be of significant interest for thermometry and optical heating.

  7. Centrifugal pumps

    CERN Document Server

    Anderson, HH

    1981-01-01

    Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The

  8. Quadrupole Moments of odd-A 53-63Mn: First use of optical pumping in the ISOLDE cooler/buncher

    Science.gov (United States)

    Babcock, Carla; Collaps Collaboration

    2016-09-01

    The technique of optical pumping has been used in the ISOLDE (CERN) cooler/buncher ion trap in order to study the previously inaccessible quadrupole moments of neutron-rich manganese ions via collinear laser spectroscopy. Previously, the insensitivity of the ground state atomic transitions to the quadrupole interaction prevented the determination of the electric quadrupole moment with any reasonable accuracy. Instead, a transition from an ionic metastable state was used and this state was populated via optical pumping. This was done in the bunching region of the ion trap, to allow multiple laser-ion interactions. Spectroscopic quadrupole moments were measured for the odd-even isotopes in the range 53-63Mn. They were compared to the predictions of three modern shell model effective interactions. The inclusion of both the 1 νg9 / 2 and 2 νd5 / 2 orbitals in the model space was thus shown to be necessary to reproduce the observed increase in the quadrupole deformation from N = 36 onwards. Specifically, the inclusion of the 2 νd5 / 2 orbital induces an increase in neutron and proton excitations across the proposed gaps at N = 40 and Z = 28 , leading to an increase in deformation in the more neutron-rich isotopes.

  9. Gamma-Radiation-Induced Degradation of Actively Pumped Single-Mode Ytterbium-Doped Optical Laser - Postprint

    Science.gov (United States)

    2015-01-01

    Nicholas G. Usechak Optoelectronics Technology Branch Aerospace Components & Subsystems Division Briana Singleton, Michael Pochet, J. Petrosky, and...NUMBER Optoelectronics Technology Branch Aerospace Components & Subsystems Division Air Force Research Laboratory, Sensors Directorate Wright...was measured using both the pump and signal lasers. A pristine 2- meter long passive patch cable with ceramic ferrules was characterized using a

  10. Pumping life

    DEFF Research Database (Denmark)

    Sitsel, Oleg; Dach, Ingrid; Hoffmann, Robert Daniel

    2012-01-01

    of membrane proteins: P-type ATPase pumps. This article takes the reader on a tour from Aarhus to Copenhagen, from bacteria to plants and humans, and from ions over protein structures to diseases caused by malfunctioning pump proteins. The magazine Nature once titled work published from PUMPKIN ‘Pumping ions......’. Here we illustrate that the pumping of ions means nothing less than the pumping of life....

  11. Nonlinear optical properties of near-infrared region Ag2S quantum dots pumped by nanosecond laser pulses

    Directory of Open Access Journals (Sweden)

    Li-wei Liu

    2015-08-01

    Full Text Available This study investigates near-infrared region Ag2S quantum dots (QDs and their nonlinear optical response under 532 nm nanosecond laser pulses. Our experimental result shows that nonlinear transmission is reduced from 0.084 to 0.04. The observed narrowing behavior of the output pulse width shows superior optical limiting. We discuss the physical mechanisms responsible for the nonlinear optical response of the QDs. The average size of the nanocrystals was 5.5 nm. Our results suggest the possibility of using these Ag2S QDs for photoelectric, biosensor, optical ranging, and self-adaptive technologies.

  12. Cavity-induced phase stability to decelerate a fast molecular beam via feedback-controlled time-varying optical pumps

    CERN Document Server

    Lan, Zhihao

    2014-01-01

    We have identified a novel phase stability mechanism from the intracavity field-induced self-organization of a fast-moving molecular beam into travelling molecular packets in the bad cavity regime, which is then used to decelerate the molecular packets by feedback-controlled time-varying laser pumps to the cavity. We first applied the linear stability analysis to derive an expression for this self-organization in the adiabatic limit and show that the self-organization of the beam leads to the formation of travelling molecular packets, which in turn function as a dynamic Bragg grating, thus modulating periodically the intracavity field by superradiant scattering of the pump photons. The modulation encodes the position information of the molecular packets into the output of the intracavity field instantaneously. We then applied time-varying laser pumps that are automatically switched by the output of the intracavity field to slow down the molecular packets via a feedback mechanism and found that most of the mol...

  13. 光泵浦远红外气体激光器的研究发展%Research and development for optically pumped far-infrared gas laser

    Institute of Scientific and Technical Information of China (English)

    曲彦臣; 陈惠颖; 耿利杰; 赵卫疆

    2014-01-01

    远红外激光具有穿透性强、光子能量低、带宽宽、通信传输容量大等优点,在公共安全、环境探测、生物医学、天文观测、军事以及通信等方面得到了广泛应用。在介绍了远红外波段激光器发展的基础之上,对产生远红外激光的各种方式进行了对比分析和总结,讨论了光泵浦远红外气体激光器的技术优势,并针对近年来远红外激光工作介质及其新谱线进行了归纳。通过对连续和脉冲光泵浦远红外气体激光器发展的回顾,结合该领域的一些重点研究方向,给出了未来光泵浦远红外气体激光器的研究趋势。%Far infrared laser sources have many properties of strong penetration, low photon energy, wide bandwidth, large transmission capacity of communication, have been widely applications in public security, environmental monitoring, biomedical diagnostics, astronomical observation, military and communicational application, etc. The technological advantages of the optically pumped far infrared gas laser were gave by comparing a variety of ways to produce far infrared laser based on introducing their development. Summarized far-infrared laser mediums and their new lines of the recent years. At last, the research trends of optically pumped far infrared which were summarized by reviewing the continuous and pulsed optically pumped far-infrared gas laser development, combining with some of the key research directions in this field were indicated.

  14. Magnetocaloric pump

    Science.gov (United States)

    Brown, G. V.

    1973-01-01

    Very cold liquids and gases such as helium, neon, and nitrogen can be pumped by using magnetocaloric effect. Adiabatic magnetization and demagnetization are used to alternately heat and cool slug of pumped fluid contained in closed chamber.

  15. The optical pumping of alkali atoms using coherent radiation from semi-conductor injection lasers and incoherent radiation from resonance lamps

    Science.gov (United States)

    Singh, G.

    1973-01-01

    An experimental study for creating population differences in the ground states of alkali atoms (Cesium 133) is presented. Studies made on GaAs-junction lasers and the achievement of population inversions among the hyperfine levels in the ground state of Cs 133 by optically pumping it with radiation from a GaAs diode laser. Laser output was used to monitor the populations in the ground state hyperfine levels as well as to perform the hyperfine pumping. A GaAs laser operated at about 77 K was used to scan the 8521 A line of Cs 133. Experiments were performed both with neon-filled and with paraflint-coated cells containing the cesium vapor. Investigations were also made for the development of the triple resonance coherent pulse technique and for the detection of microwave induced hyperfine trasistions by destroying the phase relationships produced by a radio frequency pulse. A pulsed cesium resonance lamp developed, and the lamp showed clean and reproducible switching characteristics.

  16. On the interpretation of negative birefringence observed in strong-field optical pump-probe experiments: high-order Kerr and plasma grating effects

    CERN Document Server

    Karras, G; Houzet, J; Hertz, E; Billard, F; Lavorel, B; Faucher, O

    2013-01-01

    The analysis of negative birefringence optically induced in major air components (Loriot et al., [1, 2]) is revisited in light of the recently reported plasma grating-induced phase-shift effect predicted for strong field pump-probe experiments (Wahlstrand and Milchberg, [3]). The nonlinear birefrin- gence induced by a short and intense laser pulse in argon is measured by femtosecond time-resolved polarimetry. The experiments are performed with degenerate colors, where the pump and probe beam share the same spectrum, or with two different colors and non-overlapping spectra. The in- terpretation of the experimental results is substantiated using a numerical 3D+1 model accounting for nonlinear propagation effects, cross-beam geometry of the interacting laser pulses, and detec- tion technique. The model also includes the ionization rate of argon and high-order Kerr indices introduced by Loriot et al. enabling to assess the contribution of both terms to the observed effect. The results show that the ionization-ind...

  17. Heat pumps

    CERN Document Server

    Macmichael, DBA

    1988-01-01

    A fully revised and extended account of the design, manufacture and use of heat pumps in both industrial and domestic applications. Topics covered include a detailed description of the various heat pump cycles, the components of a heat pump system - drive, compressor, heat exchangers etc., and the more practical considerations to be taken into account in their selection.

  18. A Diode-Stack End-Pumped Electro-Optically Q-Switched Nd:YAG Slab Oscillator-Amplifier System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-Li; YAN Ying; LI Dai-Jun; SHI Peng; DU Ke-Ming

    2008-01-01

    A laser diode-stack end-pumped electro-optically Q-switched Nd:YAG slab oscillator-amplifier system with near-diffraction-limited output is demonstrated by a stable-unstable hybrid resonator. The average power of 100 W at a repetition rate or 10kHz with a pulse width 14.7ns and average power of 76.3 W at a repetition rate of 5kHz with a pulse width of 10.2ns are measured. At the repetition rate of 10 kHz and at an output power of 89 W, the beam quality factors M2 in the unstable and stable directions are 1.3 and 1.5, respectively.

  19. Remote detected Low-Field MRI using an optically pumped atomic magnetometer combined with a liquid cooled pre-polarization coil

    Science.gov (United States)

    Hilschenz, Ingo; Ito, Yosuke; Natsukawa, Hiroaki; Oida, Takenori; Yamamoto, Tetsuya; Kobayashi, Tetsuo

    2017-01-01

    Superconducting quantum interference devices are widely used in basic and clinical biomagnetic measurements such as low-field magnetic resonance imaging and magnetoencephalography primarily because they exhibit high sensitivity at low frequencies and have a wide bandwidth. The main disadvantage of these devices is that they require cryogenic coolants, which are rather expensive and not easily available. Meanwhile, with the advances in laser technology in the past few years, optically pumped atomic magnetometers (OPAMs) have been shown to be a good alternative as they can have adequate noise levels and are several millimeters in size, which makes them significantly easier to use. In this study, we used an OPAM module operating at a Larmor frequency of 5 kHz to acquire NMR and MRI signals. This study presents these initial results as well as our initial attempts at imaging using this OPAM module. In addition, we have designed a liquid-cooled pre-polarizing coil that reduces the measurement time significantly.

  20. Remote detected Low-Field MRI using an optically pumped atomic magnetometer combined with a liquid cooled pre-polarization coil.

    Science.gov (United States)

    Hilschenz, Ingo; Ito, Yosuke; Natsukawa, Hiroaki; Oida, Takenori; Yamamoto, Tetsuya; Kobayashi, Tetsuo

    2017-01-01

    Superconducting quantum interference devices are widely used in basic and clinical biomagnetic measurements such as low-field magnetic resonance imaging and magnetoencephalography primarily because they exhibit high sensitivity at low frequencies and have a wide bandwidth. The main disadvantage of these devices is that they require cryogenic coolants, which are rather expensive and not easily available. Meanwhile, with the advances in laser technology in the past few years, optically pumped atomic magnetometers (OPAMs) have been shown to be a good alternative as they can have adequate noise levels and are several millimeters in size, which makes them significantly easier to use. In this study, we used an OPAM module operating at a Larmor frequency of 5kHz to acquire NMR and MRI signals. This study presents these initial results as well as our initial attempts at imaging using this OPAM module. In addition, we have designed a liquid-cooled pre-polarizing coil that reduces the measurement time significantly.

  1. Optimal densities of alkali metal atoms in an optically pumped K-Rb hybrid atomic magnetometer considering the spatial distribution of spin polarization.

    Science.gov (United States)

    Ito, Yosuke; Sato, Daichi; Kamada, Keigo; Kobayashi, Tetsuo

    2016-07-11

    An optically pumped K-Rb hybrid atomic magnetometer can be a useful tool for biomagnetic measurements due to the high spatial homogeneity of its sensor property inside a cell. However, because the property varies depending on the densities of potassium and rubidium atoms, optimization of the densities is essential. In this study, by using the Bloch equations of K and Rb and considering the spatial distribution of the spin polarization, we confirmed that the calculation results of spin polarization behavior are in good agreement with the experimental data. Using our model, we calculated the spatial distribution of the spin polarization and found that the optimal density of K atoms is 3 × 1019 m-3 and the optimal density ratio is nK/nRb ~ 400 to maximize the output signal and enhance spatial homogeneity of the sensor property.

  2. Investigation of narrow-band semiconductor quantum well structures using a synchronously-pumped optical parametric oscillator

    CERN Document Server

    Marsden, P A

    2001-01-01

    Measurements of spin relaxation processes were made in the technologically interesting InGaAs/lnP quantum wells system. The first non-linear pump and probe measurements were performed in a single 80A lattice-matched InGaAs/lnP quantum well layer. To make these measurements a synchronously-pumped parametric oscillator was constructed, using periodically-poled lithium niobate as its non-linear element. Spin relaxation measurements on InGaAs/lnP quantum wells at low (4K) temperature reveal spin-lifetimes of order 50ps, similar to those measured in the wider-gap GaAs/AIGaAs system. At room temperature the spin-lifetimes were measured to be 5ps, an order of magnitude faster than those for GaAs/AIGaAs or InGaAs/lnAIAs quantum wells of similar specification. Investigations of dominant carrier species and their associated spin relaxation were made as a function of temperature. A model was constructed for comparison to the experimental data showing the dominance of excitons at low temperature, with un-bound electron-h...

  3. Heat pumps

    CERN Document Server

    Brodowicz, Kazimierz; Wyszynski, M L; Wyszynski

    2013-01-01

    Heat pumps and related technology are in widespread use in industrial processes and installations. This book presents a unified, comprehensive and systematic treatment of the design and operation of both compression and sorption heat pumps. Heat pump thermodynamics, the choice of working fluid and the characteristics of low temperature heat sources and their application to heat pumps are covered in detail.Economic aspects are discussed and the extensive use of the exergy concept in evaluating performance of heat pumps is a unique feature of the book. The thermodynamic and chemical properties o

  4. Strain distribution in thin concrete pavement panels under three-point loading to failure with pre-pulse-pump Brillouin optical time domain analysis (Presentation Video)

    Science.gov (United States)

    Bao, Yi; Cain, John; Chen, Yizheng; Huang, Ying; Chen, Genda; Palek, Leonard

    2015-04-01

    Thin concrete panels reinforced with alloy polymer macro-synthetic fibers have recently been introduced to rapidly and cost-effectively improve the driving condition of existing roadways by laying down a fabric sheet on the roadways, casting a thin layer of concrete, and then cutting the layer into panels. This study is aimed to understand the strain distribution and potential crack development of concrete panels under three-point loading. To this end, six full-size 6ft×6ft×3in concrete panels were tested to failure in the laboratory. They were instrumented with three types of single-mode optical fiber sensors whose performance and ability to measure the strain distribution and detect cracks were compared. Each optical fiber sensor was spliced and calibrated, and then attached to a fabric sheet using adhesive. A thin layer of mortar (0.25 ~ 0.5 in thick) was cast on the fabric sheet. The three types of distributed sensors were bare SM-28e+ fiber, SM-28e+ fiber with a tight buffer, and concrete crack cable, respectively. The concrete crack cable consisted of one SM-28e+ optical fiber with a tight buffer, one SM-28e+ optical fiber with a loose buffer for temperature compensation, and an outside protective tight sheath. Distributed strains were collected from the three optical fiber sensors with pre-pulse-pump Brillouin optical time domain analysis in room temperature. Among the three sensors, the bare fiber was observed to be most fragile during construction and operation, but most sensitive to strain change or micro-cracks. The concrete crack cable was most rugged, but not as sensitive to micro-cracks and robust in micro-crack measurement as the bare fiber. The ruggedness and sensitivity of the fiber with a tight buffer were in between the bare fiber and the concrete crack cable. The strain distribution resulted from the three optical sensors are in good agreement, and can be applied to successfully locate cracks in the concrete panels. It was observed that the

  5. Planar KrCl* excilamp pumped by transverse self-sustained discharge with optical system for radiation concentration

    Energy Technology Data Exchange (ETDEWEB)

    Panchenko, A N [High-current Electronics Institute, Academicheskiy Av., 2/3, Tomsk 634055 (Russian Federation); Tarasenko, V F [High-current Electronics Institute, Academicheskiy Av., 2/3, Tomsk 634055 (Russian Federation); Belokurov, A N [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina); Mendoza, P [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina); Rios, I [INVAP S.E. Company, F.P.Moreno, 1089, CP8400, S.C. de Bariloche, Rio Negro (Argentina)

    2006-07-15

    The design and emission parameters of a spontaneous radiation source (excilamp) at a 222 nm wavelength are presented. To obtain a high-power UV radiation, a volume transverse discharge was used in the high-pressure Ne-Kr-HCl mixture. A radiation power density of 1 kW cm{sup -2} was gained at the excilamp output at a 2 mJ pulse energy. Successful attempts were made to synchronize the excilamp pulse with the pulse of second laser source. An optical system was developed to deliver and concentrate the UV radiation on to the area with a specified geometry. The method of modelling and analysis technique of the optical system using the OptiCAD 9.3 Optical Analysis Program software is described, as well.

  6. Mid-Infrared Optical Parametric Oscillator Based on All-Solid-State-Pumped Periodically Poled LiNbO

    Institute of Scientific and Technical Information of China (English)

    林学春; 毕勇; 姚爱云; 孔宇鹏; 张瑛; 孙志培; 李瑞宁; 崔大复; 许祖彦; 李健

    2003-01-01

    We report the tunable mid-infrared generation with a periodically poled LiNbO3 (PPLN). Using an all-solid-statepumped Nd: YVO4 laser as the pump source and a PPLN nonlinear crystal with grating periods of 28.2-30.8 μm,we have achieved wavelength conversion in the 2.90-4.05 μm spectral range by period tuning. The use of confocal cavity design has brought a compact, all-solid-state configuration with an average output powers of idler up to ~ 200 mW. The maximum power of 277mW was obtained at the wavelength of 3.35μm.

  7. Temperature-dependent strain and temperature sensitivities of fused silica single mode fiber sensors with pulse pre-pump Brillouin optical time domain analysis

    Science.gov (United States)

    Bao, Yi; Chen, Genda

    2016-06-01

    This paper reports a distributed temperature and strain sensor based on pulse pre-pump Brillouin optical time domain analysis. An uncoated, telecom-grade fused silica single-mode fiber as a distributed sensor was calibrated for its sensitivity coefficients under various strains and temperatures up to 800 °C. The Brillouin frequency of fiber samples changed nonlinearly with temperature and linearly with strain. The temperature sensitivity decreased from 1.113 to 0.830 MHz /°C in the range of 22-800 °C. The strain sensitivity was reduced from 0.054 to 0.042 MHz /μɛ as the temperature increased from 22 to 700 °C and became unstable at higher temperatures due to creep effect. The strain measurement range was reduced from 19 100 to 6000 μɛ in the temperature range of 22-800 °C due to fused silica’s degradation. The calibrated fiber optic sensor demonstrated adequate accuracy and precision for strain and temperature measurements and stable performance in heating-cooling cycles. It was validated in an application setting.

  8. Centrifugal pumps

    CERN Document Server

    Gülich, Johann Friedrich

    2014-01-01

    This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The d...

  9. Spin relaxation of positive trions in InAs/GaAs quantum dots: the role of hyperfine interaction

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Pierre-Francois; Lombez, Laurent; Urbaszek, Bernhard; Marie, Xavier; Amand, Thierry; Renucci, Pierre [Laboratoire de Nanophysique Magnetisme et Optoelectronique, INSA, 31077 Toulouse Cedex 4 (France); Eble, Benoit; Krebs, Olivier; Lemaitre, Aristide; Voisin, Paul [CNRS-Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France); Kalevich, Vladimir K.; Kavokin, Kyrill V. [Ioffe Physico-Technical Institute, St. Petersburg 194021 (Russian Federation)

    2006-12-15

    We report on positive trion (X{sup +}) spin relaxation in self-assembled InAs/GaAs quantum dots. The hyperfine interaction between the electron and nuclear spins acts as a randomly oriented magnetic field for the electron spin, giving rise to ensemble dephasing and thus to partial relaxation in less than 1 ns. Time-resolved photoluminescence polarization measurements carried out on an ensemble of InAs/GaAs quantum dots, charged with excess holes by proximity p-doping, reveal this peculiar dynamics. The fast polarization decrease can be efficiently suppressed by screening the hyperfine interaction with a longitudinal magnetic field of 100 mT. The quenching of this hyperfine-induced relaxation is also evidenced for a single charge-tunable quantum dot in the regime of X{sup +} photoluminescence and excited with modulated polarization to prevent dynamic nuclear polarization. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. 200 mJ optically pumped ammonia terahertz laser%200mJ光泵浦氨气太赫兹激光器

    Institute of Scientific and Technical Information of China (English)

    苗亮; 左都罗; 纠智先; 程祖海

    2011-01-01

    利用光栅选支调谐的TEA CO2激光器作为泵浦源设计了高能量脉冲光泵浦太赫兹激光器.太赫兹激光谐振腔由2m长的石英玻璃管、GaAs泵浦光输入窗和SiO2太赫兹光输出窗组成,氨气充入谐振腔内作为增益介质.太赫兹激光的波长由自主设计的金属线栅F-P干涉仪测量.实验中在多个波长处都获得了强烈的太赫兹光输出,其中151.5 μm太赫兹光的输出脉冲能量高达204 mJ,对应的泵浦光能量为32 J.最后,还给出了利用151.5μm太赫兹光进行透视成像的实验结果.%An optically pumped pulsed terahertz laser is presented. The pump laser is a line-tunable TEA CO2 laser. The terahertz cavity consists of a 2 m-long quartz glass tube, a GaAs input coupler and a SiO2 output coupler, and is filled with ammo-, nia gas as terahertz active medium. Intense terahertz radiation is emitted at different wavelengths from the terahertz laser. The terahertz wavelengths are measured by a Fabry-Perot interferometer which is composed of two metal grids. As high as 204 mJ pulse energy is obtained at 151. 5 um wavelength when the cavity is pumped by a 32 J CO2 laser. The terahertz laser is applied in transmission imaging, and some preliminary imaging results are presented.

  11. Bound states in optical absorption of semiconductor quantum wells containing a two-dimensional electron Gas

    Science.gov (United States)

    Huard; Cox; Saminadayar; Arnoult; Tatarenko

    2000-01-01

    The dependence of the optical absorption spectrum of a semiconductor quantum well on two-dimensional electron concentration n(e) is studied using CdTe samples. The trion peak (X-) seen at low n(e) evolves smoothly into the Fermi edge singularity at high n(e). The exciton peak (X) moves off to high energy, weakens, and disappears. The X,X- splitting is linear in n(e) and closely equal to the Fermi energy plus the trion binding energy. For Cd0.998Mn0.002Te quantum wells in a magnetic field, the X,X- splitting reflects unequal Fermi energies for M = +/-1/2 electrons. The data are explained by Hawrylak's theory of the many-body optical response including spin effects.

  12. Dual-channel in-situ optical imaging system for quantifying lipid uptake and lymphatic pump function

    Science.gov (United States)

    Kassis, Timothy; Kohan, Alison B.; Weiler, Michael J.; Nipper, Matthew E.; Cornelius, Rachel; Tso, Patrick; Brandon Dixon, J.

    2012-08-01

    Nearly all dietary lipids are transported from the intestine to venous circulation through the lymphatic system, yet the mechanisms that regulate this process remain unclear. Elucidating the mechanisms involved in the functional response of lymphatics to changes in lipid load would provide valuable insight into recent implications of lymphatic dysfunction in lipid related diseases. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. The imaging platform provides the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. Utilizing post-acquisition image processing algorithms, we can quantify correlations between vessel pump function, lymph flow, and lipid concentration of mesenteric lymphatic vessels in situ. All image analysis is automated with customized LabVIEW virtual instruments; local flow is measured through lymphocyte velocity tracking, vessel contraction through measurements of the vessel wall displacement, and lipid uptake through fluorescence intensity tracking of an orally administered fluorescently labelled fatty acid analogue, BODIPY FL C16. This system will prove to be an invaluable tool for scientists studying intestinal lymphatic function in health and disease, and those investigating strategies for targeting the lymphatics with orally delivered drugs to avoid first pass metabolism.

  13. Thin-disk laser pump schemes for large number of passes and moderate pump source quality

    Science.gov (United States)

    Schuhmann, Karsten; Hänsch, Theodor W.; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo

    2015-11-01

    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  14. Thin-disk laser pump schemes for large number of passes and moderate pump source quality.

    Science.gov (United States)

    Schuhmann, Karsten; Hänsch, Theodor W; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo

    2015-11-10

    Thin-disk laser pump layouts yielding an increased number of passes for a given pump module size and pump source quality are proposed. These layouts result from a general scheme based on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard, commercially available pump optics with an additional mirror pair. More pump passes yield better efficiency, opening the way for the usage of active materials with low absorption. In a standard multipass pump design, scaling of the number of beam passes brings about an increase in the overall size of the optical arrangement or an increase in the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications.

  15. Thin-disk laser pump schemes for large number of passes and moderate pump source quality

    CERN Document Server

    Schuhmann, K; Kirch, K; Knecht, A; Kottmann, F; Nez, F; Pohl, R; Taqqu, D; Antognini, A

    2015-01-01

    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  16. Qualitative and quantitative analyses of the morphological-dynamics of early cardiac pumping function using video densitometry and optical coherence tomography (OCT)

    DEFF Research Database (Denmark)

    Happel, C.; Männer, J.; Thommes, J.

    Introduction: During the initial phase of its pump action, vertebrate embryonic hearts are seen as valveless tubular pumps. It was traditionally thought that these tubular hearts generate unidirectional blood flow via peristalsis. Recently, however, the pumping mechanism of early embryonic hearts...

  17. Qualitative and quantitative analyses of the morphological-dynamics of early cardiac pump action using video densidometry and optical coherence tomography (OCT)

    DEFF Research Database (Denmark)

    Männer, Jörg; Thrane, Lars; Thommes, Jan

    2010-01-01

    During the initial phase of its pump action, vertebrate embryonic hearts are seen as valveless tubular pumps. It was traditionally thought that these tubular hearts generate unidirectional blood flow via peristalsis. Recently, however, the pumping mechanism of early embryonic hearts has become a ...

  18. 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....

  19. Ferroelectric Pump

    Science.gov (United States)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    2000-01-01

    A ferroelectric pump has one or more variable volume pumping chambers internal to a housing. Each chamber has at least one wall comprising a dome shaped internally prestressed ferroelectric actuator having a curvature and a dome height that varies with an electric voltage applied between an inside and outside surface of the actuator. A pumped medium flows into and out of each pumping chamber in response to displacement of the ferroelectric actuator. The ferroelectric actuator is mounted within each wall and isolates each ferroelectric actuator from the pumped medium, supplies a path for voltage to be applied to each ferroelectric actuator, and provides for positive containment of each ferroelectric actuator while allowing displacement of the entirety of each ferroelectric actuator in response to the applied voltage.

  20. A high-field 3He Metastability Exchange Optical Pumping polarizer operating in a 1.5 T medical scanner for lung MRI

    CERN Document Server

    Collier, G; Wojna, A; Głowacz, B; Suchanek, M; Olejniczak, Z; Dohnalik, T

    2013-01-01

    After being hyperpolarized using the technique of Metastability Exchange Optical Pumping (MEOP), 3He can be used as a contrast agent for lung magnetic resonance imaging (MRI). MEOP is usually performed at low magnetic field (~ 1 mT) and low pressure (~ 1 mbar), which results in a low magnetization production rate. A delicate polarization-preserving step of compression is also required. It was demonstrated in sealed cells that high nuclear polarization values can be obtained at higher pressures with MEOP, if performed at high magnetic field (non-standard conditions). In this work the feasibility of building a high-field polarizer that operates within a commercial 1.5 T scanner was evaluated. Preliminary measurements of nuclear polarization with sealed cells filled at different 3He gas pressures (1.33 to 267 mbar) were performed. The use of an annular shape for the laser beam increased by 25 % the achievable nuclear polarization equilibrium value (Meq) at 32 and 67 mbar as compared to a Gaussian beam shape. Meq...

  1. Wafer-scale crack-free AlGaN on GaN through two-step selective-area growth for optically pumped stimulated emission

    Science.gov (United States)

    Ko, Young-Ho; Bae, Sung-Bum; Kim, Sung-Bock; Kim, Dong Churl; Leem, Young Ahn; Cho, Yong-Hoon; Nam, Eun-Soo

    2016-07-01

    Crack-free AlGaN template has been successfully grown over entire 2-in. wafer by using 2-step selective-area growth (SAG). The GaN truncated structure was obtained by vertical growth mode with low growth temperature. AlGaN of second step was grown under lateral growth mode. Low pressure enhanced the relative ratio of lateral to vertical growth rate as well as absolute overall growth rate. High V/III ratio was favorable for lateral growth mode. Crack-free planar AlGaN was obtained under low pressure of 30 Torr and high V/III ratio of 4400. The AlGaN was crack-free over entire 2-in. wafer and had quite uniform Al-mole fraction. The dislocation density of the AlGaN with 20% Al-composition was as low as ~7.6×108 /cm2, measured by cathodoluminescence. GaN/AlGaN multi-quantum well (MQW) with cladding and waveguide layers were grown on the crack-free AlGaN template with low dislocation density. It was confirmed that the MQW on the AlGaN template emitted the stimulated emission at 355.5 nm through optical pumping experiment. The AlGaN obtained by 2-step SAG would provide high crystal quality for highly-efficient optoelectronic devices as well as the ultraviolet laser diode.

  2. Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion Regime

    Directory of Open Access Journals (Sweden)

    Javier Abreu-Afonso

    2014-10-01

    Full Text Available A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For the specific fiber of the experiment, the band shift at rates ­–0.04 nm/ºC and 0.3 nm/ºC, respectively. Strain causes the parametric bands to shift in the opposite way. The signal band shifted 2.8 nm/me and the idler -5.4 nm/me. Experimental observations are backed by numerical simulations.

  3. DEVICE FOR MEASURMENT OF RELAXATION TIME OF THE BLEACHED STATE OF OPTICAL MATERIALS BY THE «PUMP-PROBE» METHOD IN SUB-ΜS TIME DOMAIN

    Directory of Open Access Journals (Sweden)

    I. V. Glazunov

    2016-01-01

    Full Text Available The use of passive shutters to control the duration of the light pulses is an important aspect in the miniature and microchip lasers. One of the key spectroscopic characteristics which determine the properties of the material, which can be used as a passive shutter is relaxation time of its bleached state.We describe a device for determination of relaxation time of the bleached state in optical materials by the «pump-probe» method in the sub-μs time domain. This device allows one to determine relaxation times for materials which absorb at the light wavelength of 1.5 μm, e.g., materials doped with cobalt ions Co2+. The results of test examinations of the device are described, and the relaxation time of the bleached state of Co2+ ions is measured for a novel material – transparent glass-ceramics with Co2+:Ga2 O3 nanophase – amounting to 190 ± 6 ns. 

  4. Penis Pump

    Science.gov (United States)

    ... claim that they can be used to increase penis size, but there's no evidence that they work for ... circumstances, using a penis pump might help your penis maintain its natural size and shape after prostate surgery or if you ...

  5. Vacuum pump age effects by the exposure to the corrosive gases on the Cr etch rate as observed using optical emission spectroscopy in an Ar/O{sub 2}/Cl{sub 2} mixed plasma

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seolhye; Roh, Hyun-Joon; Jang, Yunchang; Jeong, Sangmin; Ryu, Sangwon; Choe, Jae-Myung; Kim, Gon-Ho, E-mail: ghkim@snu.ac.kr

    2016-03-31

    Vacuum pumps of different ages were used to prepare Cl{sub 2} based plasmas for use in Cr etching. The effects of the vacuum pump age on the etching results were investigated using optical emission spectroscopy analysis. The composition of gas at the base pressure was mainly nitrogen and oxygen, although the ratio depended on the vacuum pump age and therefore, modulated the etch rate in a manner that was difficult to monitor. The effects of the pump age on the etch rate were clearly observed in the Cl{sub 2} plasma-assisted chromium film etching process, in which oxygen and chlorine radicals were responsible for the etching process. The electron energy distribution function (EEDF), which provided a proxy for the thermal equilibrium properties of the etching plasmas, was monitored. The shape of EEDF was derived from an analysis of the optical emission spectral data using an analysis model described previously. Because molecular nitrogen has a higher threshold energy and a larger cross-section of inelastic collisional processes than oxygen, the tail of the EEDF depends on the mixing ratio between nitrogen and oxygen. The various mechanisms that contribute to the chromium etch rate varied with subtle differences in the vacuum conditions, which were determined by age of the turbo molecular pump. The rates at which oxygen and chlorine radicals were generated were estimated using the measured EEDF, and the estimated oxygen radical and etching product contents were verified by comparing the residual gas analyzer data. The results revealed that the residual nitrogen partial pressures in two etchers equipped with either a new or an aged pump differed by 0.18%, and the EEDF tail areas differed by 10{sup −4}. Importantly, the chromium etch rates in these two instruments differed by 30%. These results suggest that the chamber-to-chamber mismatch should be monitored during plasma-assisted device fabrication processes. - Highlights: • We observed the vacuum pump age effect

  6. 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.

  7. LD-pumped high repetition rate Q-switched Nd:YVO4 laser by using La3Ga5SiO14 single crystal electro-optic modulator

    Institute of Scientific and Technical Information of China (English)

    Chunyu Wang; Huaguo Zang; Xiaoli Li; Yutian Lu; Xiaolei Zhu

    2006-01-01

    A diode-end-pumped electro-optic (EO) Q-switched Nd:YVO4 laser operating at repetition rate of 10 kpps (pulses per second) was reported. A block of La3Ga5SiO14 (LGS) single crystal was used as a Q-switch and the driver was a metal oxide semiconductor field effect transistor (MOS-FET) pulser of high repetition rate and high voltage. At continuous wave (CW) operation, the slope efficiency of the laser was 46%, and maximum optical-to-optical efficiency was 38.5%. Using an output coupler with transmission of 70%, a 10-kpps Q-switched pulse train with 0.4-mJ monopulse energy and 8.2-ns pulse width was achieved, the optical conversion efficiency was around 15%, and the beam quality M2 factor was less than 1.2.

  8. Modeling of forward pump EDFA under pump power through MATLAB

    Science.gov (United States)

    Raghuwanshi, Sanjeev Kumar; Sharma, Reena

    2015-05-01

    Optical fiber loss is a limiting factor for high-speed optical network applications. However, the loss can be compensated by variety of optical amplifiers. Raman amplifier and EDFA amplifier are widely used in optical communication systems. There are certain advantages of EDFA over Raman amplifier like amplifying the signal at 1550 nm wavelength at which the fiber loss is minimum. Apart from that there is no pulse walk-off problem with an EDFA amplifier. With the advent of optical amplifiers like EDFA, it is feasible to achieve a high bit rate beyond terabits in optical network applications. In our study, a MATLAB simulink-based forward pumped EDFA (operating in C-band 1525-1565 nm) simulation platform has been devised to evaluate the following performance parameters like gain, noise figure, amplified spontaneous emission power variations of a forward pumped EDFA operating in C-band (1525-1565 nm) as functions of Er3+ fiber length, injected pump power, signal input power, and Er3+ doping density. The effect of an input pump power on gain and noise figure was illustrated graphically. It is possible to completely characterize and optimize the EDFA performance using our dynamic simulink test bed.

  9. Compact and highly efficient laser pump cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jim J. (Dublin, CA); Bass, Isaac L. (Castro Valley, CA); Zapata, Luis E. (Livermore, CA)

    1999-01-01

    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  10. Excitons and trions in monolayer transition metal dichalcogenides: A comparative study between the multiband model and the quadratic single-band model

    Science.gov (United States)

    Van der Donck, M.; Zarenia, M.; Peeters, F. M.

    2017-07-01

    The electronic and structural properties of excitons and trions in monolayer transition metal dichalcogenides are investigated using both a multiband and a single-band model. In the multiband model we construct the excitonic Hamiltonian in the product base of the single-particle states at the conduction and valence band edges. We decouple the corresponding energy eigenvalue equation and solve the resulting differential equation self-consistently, using the finite element method (FEM), to determine the energy eigenvalues and the wave functions. As a comparison, we also consider the simple single-band model which is often used in numerical studies. We solve the energy eigenvalue equation using the FEM as well as with the stochastic variational method (SVM) in which a variational wave function is expanded in a basis of a large number of correlated Gaussians. We find good agreement between the results of both methods, as well as with other theoretical works for excitons, and we also compare with available experimental data. For trions the agreement between both methods is not as good due to our neglect of angular correlations when using the FEM. Finally, when comparing the two models, we see that the presence of the valence bands in the mutiband model leads to differences with the single-band model when (interband) interactions are strong.

  11. Oxygen Passivation Mediated Tunability of Trion and Excitons in MoS2

    KAUST Repository

    Gogoi, Pranjal Kumar

    2017-08-17

    Using wide spectral range in situ spectroscopic ellipsometry with systematic ultrahigh vacuum annealing and in situ exposure to oxygen, we report the complex dielectric function of MoS2 isolating the environmental effects and revealing the crucial role of unpassivated and passivated sulphur vacancies. The spectral weights of the A (1.92 eV) and B (2.02 eV) exciton peaks in the dielectric function reduce significantly upon annealing, accompanied by spectral weight transfer in a broad energy range. Interestingly, the original spectral weights are recovered upon controlled oxygen exposure. This tunability of the excitonic effects is likely due to passivation and reemergence of the gap states in the band structure during oxygen adsorption and desorption, respectively, as indicated by ab initio density functional theory calculation results. This Letter unravels and emphasizes the important role of adsorbed oxygen in the optical spectra and many-body interactions of MoS2.

  12. One-Pot and Efficient Synthesis of Triazolo[1,2-a]indazole-triones via Reaction of Arylaldehydes with Urazole and Dimedone Catalyzed by Silica Nanoparticles Prepared from Rice Husk

    OpenAIRE

    Asadollah Hassankhani; Sayed Zia Mohammadi; Hooshang Hamidian; Samieh Fozooni

    2011-01-01

    A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions and environmental friendliness.

  13. One-pot synthesis and antibacterial activities of novel 1H-pyridazino[1,2-a]indazole-1,6,9(2H,11H)-triones.

    Science.gov (United States)

    Sayyafi, Maryam; Soorki, Ali Abolhasani; Bazgir, Ayoob

    2008-09-01

    Synthesis of novel 1H-pyridazino[1,2-a]indazole-1,6,9(2H,11H)-triones using one-pot, three components reaction of 1,2-dihydropyridazine-3,6-dione, dimedone and aldehydes under solvent-free conditions has been reported. These products were evaluated in vitro for their antibacterial activities.

  14. One-Pot and Efficient Synthesis of Triazolo[1,2-a]indazole-triones via Reaction of Arylaldehydes with Urazole and Dimedone Catalyzed by Silica Nanoparticles Prepared from Rice Husk

    Directory of Open Access Journals (Sweden)

    Asadollah Hassankhani

    2011-10-01

    Full Text Available A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions and environmental friendliness.

  15. One-pot and efficient synthesis of triazolo[1,2-a]indazole-triones via reaction of arylaldehydes with urazole and dimedone catalyzed by silica nanoparticles prepared from rice husk.

    Science.gov (United States)

    Hamidian, Hooshang; Fozooni, Samieh; Hassankhani, Asadollah; Mohammadi, Sayed Zia

    2011-10-26

    A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions and environmental friendliness.

  16. Synthesis of (+/-)-clusianone: high-yielding bridgehead and diketone substitutions by regioselective lithiation of enol ether derivatives of bicyclo[3.3.1]nonane-2,4,9-triones.

    Science.gov (United States)

    Rodeschini, Vincent; Ahmad, Nadia M; Simpkins, Nigel S

    2006-11-09

    [Structure: see text] A concise synthesis of the polyprenylated acylphloroglucinol natural product, clusianone, in racemic form, is described. An Effenburger cyclization generated a core bicyclo[3.3.1]nonane-trione structure, which was then elaborated by means of regioselective lithiation reactions.

  17. Infrared spectrum involving forbidden transitions & coriolis interaction and identification of optically pumped far infrared laser lines in asymmetrically mono-deuterated methanol (Methanol-D1)

    Science.gov (United States)

    Mukhopadhyay, Indra

    2016-05-01

    In this paper new type of ΔK = 2 and 0 transitions have been identified in the Fourier Transform spectrum of Methanol-D1 (CH2DOH). These transitions are normally forbidden but a "Coriolis" type interaction with nearby states is believed to be contributing sufficient transition strength through intensity borrowing effect. This is the first time such forbidden transitions are reported to be identified in the excited states, in this molecule. The present conjecture is supported by observation of a many strong allowed transitions to upper terminating levels which are seen to be highly perturbed. This conclusion has been reached by comparing calculated energy levels using known molecular parameters (Pearson et al., 2012; Coudert et al., 2014; El Hilali et al., 2011; Quade et al., 1998; Richard Quade, 1998, 1999; Mukhopadhyay, 1997) and the actually observed FIR lines. The upper levels are seen to be upshifted from expected position. A closer look at the calculated energy values seems to indicate a possible interaction between the above states and other proximate torsional-rotational states could occur. The possible candidates for the interacting level manifolds are narrowed down through the presence of the forbidden transition. We also take the opportunity to propose alternate rotational quantum numbers for some of the assignments recently reported in the literature (El Hilali et al., 2011). Some ambiguities are pointed out on the data and the reported analysis. There remain too many such irregularities and we propose to gather a large body assigned transitions in a future catalog. Assignments and relevant comments on optically pumped FIR laser radiation are also made.

  18. Metastability exchange optical pumping in {sup 3}He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Batz, Marion

    2011-07-08

    Advances in metastability exchange optical pumping (MEOP) of {sup 3}He at high laser powers, with its various applications, but also at high gas pressures p{sub 3} and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B{<=}30 mT and p{sub 3}=0.63-2.45 mbar. {sup 3}He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  19. Efficient high-peak-power AlGaInAs eye-safe wavelength disk laser with optical in-well pumping.

    Science.gov (United States)

    Chang, H L; Huang, S C; Chen, Yi-Fan; Su, K W; Chen, Y F; Huang, K F

    2009-07-06

    We have demonstrated an efficient high-peak-power AlGaInAs eye-safe wavelength disk laser at 1555 nm. The quantum defect and the thermal load are significantly reduced by pumping the quantum well directly. The overall conversion efficiency is enhanced over three times compared with the barrier pumping method. With a pump peak power of 3.7 kW, an output peak power of 0.52 kW is generated at a pulse repetition rate of 20 kHz.

  20. Pumps; Pumpen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, H. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft; Hellriegel, E. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft; Pfitzner, G. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft

    1994-11-01

    The technical features of commercial pump types are described with regard to their technical, energy-related and economic parameters, and characteristic data are presented in the form of data sheets. This is to provide a basis for a comparative assessment of different technologies and technical variants. The chapter `System specifications` describes the various fields of application of pumps and the resulting specific requirements. The design and function of the different pump types are described in `Technical description`. `System and plant description dscribes the design and adaptation of pumps, i.e. the adaptation of the plant data to the system requirements. `Data compilation` provides a survey of the types and systematics of the compiled data as well as a decision aid for selecting the pumps best suited to the various applications. The `Data sheet` section describes the structure and handling of the data sheets as well as the data contained therein. The data sheets are contained in the apapendix of this report. The section `General analysis` compares typical technical, energy-related and economic characteristics of the different pump types. This is to enable a rough comparison of pump types and to facilitate decisions. The chapter `Example` illustrates the use of the data sheets by means of a selected example. (orig./GL) [Deutsch] Die vorliegende Arbeit hat zum Ziel, Technik seriengefertigter und marktgaengiger Pumpen in typisierter Form hinsichtlich ihrer technischen, energetischen und wirtschaftlichen Parameter zu beschreiben und ihre charakteristischen Kennwerte in Datenblaettern abzubilden. Damit wird ein grundlegendes Instrument fuer die vergleichende Beurteilung unterschiedlicher Techniken bzw. Technikvarianten hinsichtlich energetischer und wirtschaftlicher Kriterien geschaffen. Im Abschnitt `Systemanforderungen` erfolgt die Beschreibung der einzelnen Anwendungsbereiche fuer Pumpen mit den speziellen daraus resultierenden Anforderungen. Der Aufbau und

  1. Energy characteristics of a 16. mu. CO/sub 2/ laser pumped optically in the 4. 3 and 9. 6. mu. bands

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Stepanov, B.I.; Trushin, S.A.; Churakov, V.V.

    1978-03-01

    Results are presented of a theoretical investigation of the energy characteristics of a CO/sub 2/ molecular laser emitting in the 02/sup 0/0--01/sup 1/0 channel (16 ..mu..). It is postulated that the system is pumped by radiation from pulsed HBr and CO/sub 2/ lasers in the 4.3 and 9.6 ..mu.. bands, respectively. The optimal parameters of the laser are determined. It is shown that at pump energies of approx.0.02 J/cm/sup 2/, resonator lengths of approx.100 cm, loss coefficients of approx.0.01 cm/sup -1/, and optimal values of the pump pulse duration, pressure, and CO/sub 2/--He mixture composition, the efficiency of conversion of the 4.3 ..mu.. pump radiation energy into 16 ..mu.. stimulated emission energy attains approx.4.5%.

  2. Topological Thouless pumping of ultracold fermions

    Science.gov (United States)

    Nakajima, Shuta; Tomita, Takafumi; Taie, Shintaro; Ichinose, Tomohiro; Ozawa, Hideki; Wang, Lei; Troyer, Matthias; Takahashi, Yoshiro

    2016-04-01

    An electron gas in a one-dimensional periodic potential can be transported even in the absence of a voltage bias if the potential is slowly and periodically modulated in time. Remarkably, the transferred charge per cycle is sensitive only to the topology of the path in parameter space. Although this so-called Thouless charge pump was first proposed more than thirty years ago, it has not yet been realized. Here we report the demonstration of topological Thouless pumping using ultracold fermionic atoms in a dynamically controlled optical superlattice. We observe a shift of the atomic cloud as a result of pumping, and extract the topological invariance of the pumping process from this shift. We demonstrate the topological nature of the Thouless pump by varying the topology of the pumping path and verify that the topological pump indeed works in the quantum regime by varying the speed and temperature.

  3. Types of Breast Pumps

    Science.gov (United States)

    ... Devices Consumer Products Breast Pumps Types of Breast Pumps Share Tweet Linkedin Pin it More sharing options ... used for feeding a baby. Types of Breast Pumps There are three basic types of breast pumps: ...

  4. FemtoSpeX: a versatile optical pump-soft X-ray probe facility with 100 fs X-ray pulses of variable polarization.

    Science.gov (United States)

    Holldack, Karsten; Bahrdt, Johannes; Balzer, Andreas; Bovensiepen, Uwe; Brzhezinskaya, Maria; Erko, Alexei; Eschenlohr, Andrea; Follath, Rolf; Firsov, Alexander; Frentrup, Winfried; Le Guyader, Loïc; Kachel, Torsten; Kuske, Peter; Mitzner, Rolf; Müller, Roland; Pontius, Niko; Quast, Torsten; Radu, Ilie; Schmidt, Jan Simon; Schüssler-Langeheine, Christian; Sperling, Mike; Stamm, Christian; Trabant, Christoph; Föhlisch, Alexander

    2014-09-01

    Here the major upgrades of the femtoslicing facility at BESSY II (Khan et al., 2006) are reviewed, giving a tutorial on how elliptical-polarized ultrashort soft X-ray pulses from electron storage rings are generated at high repetition rates. Employing a 6 kHz femtosecond-laser system consisting of two amplifiers that are seeded by one Ti:Sa oscillator, the total average flux of photons of 100 fs duration (FWHM) has been increased by a factor of 120 to up to 10(6) photons s(-1) (0.1% bandwidth)(-1) on the sample in the range from 250 to 1400 eV. Thanks to a new beamline design, a factor of 20 enhanced flux and improvements of the stability together with the top-up mode of the accelerator have been achieved. The previously unavoidable problem of increased picosecond-background at higher repetition rates, caused by `halo' photons, has also been solved by hopping between different `camshaft' bunches in a dedicated fill pattern (`3+1 camshaft fill') of the storage ring. In addition to an increased X-ray performance at variable (linear and elliptical) polarization, the sample excitation in pump-probe experiments has been considerably extended using an optical parametric amplifier that supports the range from the near-UV to the far-IR regime. Dedicated endstations covering ultrafast magnetism experiments based on time-resolved X-ray circular dichroism have been either upgraded or, in the case of time-resolved resonant soft X-ray diffraction and reflection, newly constructed and adapted to femtoslicing requirements. Experiments at low temperatures down to 6 K and magnetic fields up to 0.5 T are supported. The FemtoSpeX facility is now operated as a 24 h user facility enabling a new class of experiments in ultrafast magnetism and in the field of transient phenomena and phase transitions in solids.

  5. Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak

    2010-11-01

    A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.

  6. Structural and vibrational analyses of new potential anticancer drug 2-(phenylmethyl)-2-azaspiro[5.11]heptadecane-1,3,7-trione

    Science.gov (United States)

    Vitnik, Željko J.; Popović-Đorđević, Jelena B.; Vitnik, Vesna D.

    2017-06-01

    The establishment of the most stable structures of 2-(phenylmethyl)-2-azaspiro[5.11]heptadecane-1,3,7-trione, potential anticancer and antimicrobial drug has been investigated in this work. A detailed interpretation of experimental and calculated IR, UV and NMR spectra were reported. The equilibrium geometry, harmonic vibrational frequencies and electronic properties have been investigated with Density Functional Theory using B3LYP/6-311++G(d,p) method. The scaled theoretical wavenumber showed very good agreement with the experimental values. The charge transfer in the molecule was confirmed with NBO analysis. Ultraviolet-visible spectrum was calculated using TD-DFT method and compared with experimental spectrum. The calculated energy and oscillator strength well reproduce the experimental data. The molecular electrostatic potential surface map portrays potential binding sites of the title molecule.

  7. High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator.

    Science.gov (United States)

    Cho, C Y; Chen, Y C; Huang, Y P; Huang, Y J; Su, K W; Chen, Y F

    2014-04-01

    We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO(4) laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEM(n,0) mode in the diode-stack directly side-pumping configuration. We successfully generate TEM(n,0) modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM(0,0) mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ.

  8. High power 888 nm optical fiber end-pumped Nd:YVO4 picosecond regenerative amplifier at hundreds kHz

    Science.gov (United States)

    Bai, Zhenao; Fan, Zhongwei; Lian, Fuqiang; Tan, Tan; Bai, Zhenxu; Yang, Chao; Kang, Zhijun; Liu, Chang

    2016-10-01

    This paper describes a demonstration of a high power 888 nm end-pumped Nd:YVO4 picosecond regenerative amplifier operated at high repetition rate. By utilizing an all-fiber mode-locking picosecond laser as seed source and 888 nm continuous wave (CW) as pumping source, we obtained regenerative amplified output at 1064.07 nm with spectrum width 0.16 nm, pulse width of 38 ps, maximum power of 21 W, and the repetition rate is continuously adjustable from 300 to 500 kHz. The regenerative amplifier has high power stability and high compact structure.

  9. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  10. Electron beam pumped semiconductor laser

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  11. Magnetic Nanoparticle Immobilized N-Propylsulfamic Acid as a Recyclable and Efficient Nanocatalyst for the Synthesis of 2H-indazolo[2,1-b]phthalazine-triones in Solvent-Free Conditions: Comparison with Sulfamic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Rostami, Amin; Tahmasbi, Bahman; Yari, Ako [Univ. of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2013-05-15

    N-Propylsulfamic acid supported onto magnetic Fe{sub 3}O{sub 4} nanoparticles (MNPs-PSA) was used as an efficient and magnetically recoverable catalyst for synthesis of 2H-Indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives from the three-component, one-pot condensation reaction of phthalhydrazide, aromatic aldehydes and cyclic 1,3-diones, in good to excellent yields at 100 .deg. C under solvent-free conditions. The catalyst was easily separated with the assistance of an external magnetic field from the reaction mixture and reused for several consecutive runs without significant loss of its catalytic efficiency. In order to compare, the synthesis of 2H-Indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives in the presence of catalytic amount of sulfamic acid (SA) under same reaction condition was also reported.

  12. Pump characteristics and applications

    CERN Document Server

    Volk, Michael

    2013-01-01

    Providing a wealth of information on pumps and pump systems, Pump Characteristics and Applications, Third Edition details how pump equipment is selected, sized, operated, maintained, and repaired. The book identifies the key components of pumps and pump accessories, introduces the basics of pump and system hydraulics as well as more advanced hydraulic topics, and details various pump types, as well as special materials on seals, motors, variable frequency drives, and other pump-related subjects. It uses example problems throughout the text, reinforcing the practical application of the formulae

  13. Influence of optical coherence on the electron spin in singly charged InP quantum dots excited by resonant laser pulses

    Science.gov (United States)

    Tomimoto, Shinichi; Kawana, Keisuke; Murakami, Akira; Masumoto, Yasuaki

    2012-06-01

    We have experimentally studied the spin dynamics of excitons, electrons, and trions in charge-tunable InP/InGaP quantum dots (QDs) excited by picosecond resonant laser pulses by observing the time-resolved Kerr rotation. In singly charged QDs, inversion of the spin polarization direction of doped electrons is found to be caused simply by variation in the pulse intensity, which is accompanied by an abrupt change of the spin coherence time. This phenomenon is reproduced by density-matrix calculations allowing for the reaction on the QD electron-trion four-level system during its coherent radiation emission. This result means that the optical coherence is another critical factor affecting electron spin coherence.

  14. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  15. 光泵亚毫米波激光的理论模型及计算方法(Ⅰ) ——半经典密度矩阵理论%The theoretical model and calculation method of optically pumped submillimeter wave laser(Ⅰ) ——The semiclassical density matrix theory

    Institute of Scientific and Technical Information of China (English)

    冉勇; 秦家银; 朱昌平; 李太全; 陶少华

    2001-01-01

    We have made a systematic study in optically pumped submillimeter wave laser. In this paper, expound a semiclassical density matrix theory, it was used by Author in theoretical study of miniature optically pumped submillimeter wave laser.%该作者曾对光泵亚毫米波激光作过系统深入地的研究。重点论述在小型光泵亚毫米波激光的理论研究中所应用的量子系统的半经典密度矩阵理论。

  16. LD side-pumped intracavity frequency-doubled high power Nd:YAG green laser based on acousto-optic Q-switch

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng-chuan; FAN Xiu-wei; XUE Lin; CHAI Hong-liang; HE Jing-liang

    2006-01-01

    A highly efficient and high power green laser generated by intracavity frequency doubling of a diode-side pumped Q-switched Nd:YAG laser has been demonstrated. In the simple L-shaped cavity geometry,the maximum green output power of 28.5 W was obtained with a pulse width of 95 ns at a pulse repetition rate of 10 kHz by using a LBO crystal for frequency doubling,corresponding to a conversion efficiency of 11% from diode pump power to pulse green power. At a pulse repetition rate of 1 kHz,6.9 mJ of pulse energy,25 ns of pulse duration and 276 kW of peak power were obtained.

  17. LMFBR with booster pump in pumping loop

    Science.gov (United States)

    Rubinstein, H.J.

    1975-10-14

    A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation.

  18. Heat pump technology

    CERN Document Server

    Von Cube, Hans Ludwig; Goodall, E G A

    2013-01-01

    Heat Pump Technology discusses the history, underlying concepts, usage, and advancements in the use of heat pumps. The book covers topics such as the applications and types of heat pumps; thermodynamic principles involved in heat pumps such as internal energy, enthalpy, and exergy; and natural heat sources and energy storage. Also discussed are topics such as the importance of the heat pump in the energy industry; heat pump designs and systems; the development of heat pumps over time; and examples of practical everyday uses of heat pumps. The text is recommended for those who would like to kno

  19. Integrated Duo Wavelength VCSEL Using an Electrically Pumped GaInAs/AlGaAs 980 nm Cavity at the Bottom and an Optically Pumped GaInAs/AlGaInAs 1550 nm Cavity on the Top

    Science.gov (United States)

    Islam, Samiha Ishrat; Islam, Arnob; Islam, Saiful

    2014-01-01

    In this work, an integrated single chip dual cavity VCSEL has been designed which comprises an electrically pumped 980 nm bottom VCSEL section fabricated using GaInAs/AlGaAs MQW active region and a 1550 nm top VCSEL section constructed using GaInAs/AlGaInAs MQW active region but optically pumped using half of the produced 980 nm light entering into it from the electrically pumped bottom cavity. In this design, the active region of the intracavity structure 980 nm VCSEL consists of 3 quantum wells (QWs) using Ga0.847In0.153As, 2 barriers using Al0.03Ga0.97As, and 2 separate confinement heterostructures (SCH) using the same material as the barrier. The active region of the top emitting 1550 nm VCSEL consists of 3 QWs using Ga0.47In0.52As, 2 barriers using Al0.3Ga0.17In0.53As, and 2 SCHs using the same material as the barrier. The top DBR and the bottom DBR mirror systems of the 1550 nm VCSEL section plus the top and bottom DBR mirror systems of the 980 nm VCSEL section have been formed using GaAs/Al0.8Ga0.2As. Computations show that the VCSEL is capable of producing 8.5 mW of power at 980 nm from the bottom side and 2 mW of power at the 1550 nm from top side. PMID:27379335

  20. Dry vacuum pumps

    Science.gov (United States)

    Sibuet, R.

    2008-05-01

    For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R&D/industries, merits over conventional pumps and future growth scope will be discussed.

  1. Nonlinear optical properties of near-infrared region Ag2S quantum dots pumped by nanosecond laser pulses

    OpenAIRE

    Li-wei Liu; Si-yi Hu; Yin-ping Dou; Tian-hang Liu; Jing-quan Lin; Yue Wang

    2015-01-01

    This study investigates near-infrared region Ag2S quantum dots (QDs) and their nonlinear optical response under 532 nm nanosecond laser pulses. Our experimental result shows that nonlinear transmission is reduced from 0.084 to 0.04. The observed narrowing behavior of the output pulse width shows superior optical limiting. We discuss the physical mechanisms responsible for the nonlinear optical response of the QDs. The average size of the nanocrystals was 5.5 nm. Our results suggest the possib...

  2. 100  kHz Yb-fiber laser pumped 3  μm optical parametric amplifier for probing solid-state systems in the strong field regime.

    Science.gov (United States)

    Archipovaite, Giedre Marija; Petit, Stéphane; Delagnes, Jean-Christophe; Cormier, Eric

    2017-03-01

    We report on a laser source operating at 100 kHz repetition rate and delivering 8 μJ few-cycle mid-IR pulses at 3 μm. The system is based on optical parametric amplification pumped by a high repetition rate Yb-doped femtosecond fiber-chirped amplifier. This high-intensity ultrafast system is a promising tool for strong-field experiments (up to 50 GV/m and 186 T) in low ionization potential atomic and molecular systems, or solid-state physics with coincidence measurements. As a proof of principle, up to the sixth harmonic has been generated in a 1 mm zinc selenide sample.

  3. 基于STM32的铯光泵磁力仪数据采集系统%Data Acquisition System of Cesium Optical-pump Magnetometer Based on STM32

    Institute of Scientific and Technical Information of China (English)

    彭俊杰; 陈永泰

    2016-01-01

    文中针对铯光泵磁力仪,设计了一种基于STM32F103ZET6处理器和现场可编辑门阵列(FP-GA)的数据采集系统,实现了对输出信号采集后的高精度测量,并且利用传感器实现了对铯光泵磁力仪的探头姿态检测.文中简要介绍了铯光泵磁力仪的基本原理和系统结构.重点针对数据采集系统的要求,介绍了该系统软件设计思路和具体细节.经过实验验证,系统样机基本工作状态良好,达到设计要求.%Aiming at cesium optical-pump magnetometer, a data acquisition system based on STM32F103ZET6 and FPGA was designed, which realized high precision measurement of the output signal and attitude detection of magnetometer probe by u-sing a sensor . Cesium optical-pump magnetometer measurement principle and system circuit structure were briefly introduced firstly. Then the requirements for the data acquisition system was focused on and how to design the various modules of the circuit was introduced. After that ,the ideas of system software design was analyzed and described in detail .The results show that the da-ta acquisition system is in good working order and can meet design requirements well.

  4. Centrifugal pump handbook

    CERN Document Server

    Pumps, Sulzer

    2010-01-01

    This long-awaited new edition is the complete reference for engineers and designers working on pump design and development or using centrifugal pumps in the field. This authoritative guide has been developed with access to the technical expertise of the leading centrifugal pump developer, Sulzer Pumps. In addition to providing the most comprehensive centrifugal pump theory and design reference with detailed material on cavitation, erosion, selection of materials, rotor vibration behavior and forces acting on pumps, the handbook also covers key pumping applications topics and operational

  5. Energy characteristics of a CO/sub 2/-laser at 16. mu. m with optical pumping in the 4. 3 and 9. 6. mu. m bands

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Stepanov, B.I.; Trushin, S.A.; Churakov, V.V.

    1978-03-01

    It now appears feasible to separate uranium isotopes with a laser operating at a wavelength about 16 ..mu..m. A molecular CO/sub 2/ pulse laser is considered that emits in the 16.18 ..mu..m channel, and its performance is analyzed. Equations are derived for calculating and optimizing the laser parameters, such as the duration of the pumping pulse, the total pressure, and the CO/sub 2/-He mixture composition. The results indicate that a conversion efficiency of 4.5% can be reached with low surface densities of the pumping energy (about 0.02 J/cm/sup 2/) and practical resonator lengths (100 to 200 cm) under otherwise optimal conditions. This compares with the maximum attainable 6.5% conversion efficiency in this mode of excitation. When the dumping pulse (at 9.6 ..mu..m) and the generated pulse (at 16 ..mu..m) overlap in time, then the role of two-photon processes increases and the maximum laser efficiency could probably be increased 1.3 times.

  6. Electrically Pumped Vertical-Cavity Amplifiers

    DEFF Research Database (Denmark)

    Greibe, Tine

    2007-01-01

    In this work, the design of electrically pumped vertical cavity semiconductor optical amplifiers (eVCAs) for use in a mode-locked external-cavity laser has been developed, investigated and analysed. Four different eVCAs, one top-emitting and three bottom emitting structures, have been designed...... and discussed. The thesis concludes with recommendations for further work towards the realisation of compact electrically pumped mode-locked vertical externalcavity surface emitting lasers....

  7. Synthesis and PASS-assisted in silico approach of some novel 2-substituted benzimidazole bearing a pyrimidine-2, 4, 6(trione system as mucomembranous protector

    Directory of Open Access Journals (Sweden)

    Bijo Mathew

    2013-01-01

    Full Text Available Purpose: The present paper demonstrates the utility of PASS computer-aided program and makes a clear comparison of predicted and observed pharmacological properties of some novel 5-[(2E-1-(1H-benzimidazol-2-yl-3-substituted phenylprop-2-en-1-ylidene] pyrimidine-2, 4, 6 (1H, 3H, 5H-triones (5a-f. Materials and Methods: The synthesis of the titled derivatives were achieved by the reaction between 2E-1-(1H-benzimidazol-2-yl-3-phenylprop-2-en-1-ones (4a-f and barbituric acid in the presence of catalytic amount of acetic acid medium. All the final structures were assigned on the basis of IR, 1 HNMR and mass spectra analysis. All the newly synthesized compounds were screened for their antiulcer activity in the pylorus-ligated rats. Results: Compounds 5b, 5e and 5c showed a percentage protection of (69.58, 69.56 and 67.17 at a dose of 50 mg/kg b.w. when compared to standard omeprazole (77.37%, 2 mg/kg b.w.. Conclusion: Scanning of stomach specimens using electron microscope revealed that the mice treated with standard and synthetic derivatives had no injury observed in stomach mucosa, which is identical to that of the control animal.

  8. Alternative backing up pump for turbomolecular pumps

    Science.gov (United States)

    Myneni, Ganapati Rao

    2003-04-22

    As an alternative to the use of a mechanical backing pump in the application of wide range turbomolecular pumps in ultra-high and extra high vacuum applications, palladium oxide is used to convert hydrogen present in the evacuation stream and related volumes to water with the water then being cryo-pumped to a low pressure of below about 1.e.sup.-3 Torr at 150.degree. K. Cryo-pumping is achieved using a low cost Kleemenco cycle cryocooler, a somewhat more expensive thermoelectric cooler, a Venturi cooler or a similar device to achieve the required minimization of hydrogen partial pressure.

  9. Future directions in 980-nm pump lasers: submarine deployment to low-cost watt-class terrestrial pumps

    Science.gov (United States)

    Gulgazov, Vadim N.; Jackson, Gordon S.; Lascola, Kevin M.; Major, Jo S.; Parke, Ross; Richard, Tim; Rossin, Victor V.; Zhang, Kai

    1999-09-01

    The demands of global bandwidth and distribution are rising rapidly as Internet usage grows. This fundamentally means that more photons are flowing within optical cables. While transmitting sources launches some optical power, the majority of the optical power that is present within modern telecommunication systems originates from optical amplifiers. In addition, modern optical amplifiers offer flat optical gain over broad wavelength bands, thus making possible dense wavelength de-multiplexing (DWDM) systems. Optical amplifier performance, and by extension the performance of the laser pumps that drive them, is central to the future growth of both optical transmission and distribution systems. Erbium-doped amplifiers currently dominate optical amplifier usage. These amplifiers absorb pump light at 980 nm and/or 1480 nm, and achieve gain at wavelengths around 1550 nm. 980 nm pumps achieve better noise figures and are therefore used for the amplification of small signals. Due to the quantum defect, 1480 nm lasers deliver more signal photon per incident photon. In addition, 1480 nm lasers are less expensive than 980 nm lasers. Thus, 1480 nm pump lasers are used for amplification in situations where noise is not critical. The combination of these traits leads to the situation where many amplifiers contain 980 nm lasers to pump the input section of the Er- doped fiber with 1480 nm lasers being used to pump the latter section of Er fiber. This can be thought of as using 980 nm lasers to power an optical pre-amplifier with the power amplification function being pump with 1480 nm radiation. This paper will focus on 980 nm pump lasers and the impact that advances in 980 nm pump technology will have on optical amplification systems. Currently, 980 nm technology is rapidly advancing in two areas, power and reliability. Improving reliability is becoming increasingly important as amplifiers move towards employing more pump lasers and using these pump lasers without redundancy

  10. Large electromagnetic pumps. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Kilman, G.B.

    1976-01-01

    The development of large electromagnetic pumps for the liquid metal heat transfer systems of fission reactors has progressed for a number of years. Such pumps are now planned for fusion reactors and solar plants as well. The Einstein-Szilard (annular) pump has been selected as the preferred configuration. Some of the reasons that electromagnetic pumps may be preferred over mechanical pumps and why the annular configuration was selected are discussed. A detailed electromagnetic analysis of the annular pump, based on slug flow, is presented. The analysis is then used to explore the implications of large size and power on considerations of electromagnetic skin effect, geometric skin effect and the cylindrical geometry.

  11. Semiconductor disk laser pumped Cr2+:Znse lasers.

    Science.gov (United States)

    Hempler, Nils; Hopkins, John-Mark; Rösener, Benno; Rattunde, Marcel; Wagner, Joachim; Fedorov, Vladimir V; Moskalev, Igor S; Mirov, Sergey B; Burns, David

    2009-09-28

    A new flexible pump source, the optically-pumped semiconductor disk laser (SDL), for the Cr(2+):ZnSe laser is reported. The SDL provides up to 6W output power at a free running central wavelength of 1.98 microm. The Cr(2+):ZnSe laser operated at an output power of 1.8W and a slope efficiency of approximately 50% with respect to absorbed pump power whilst maintaining a low output intensity noise figure of <0.14% RMS. The system required no optical isolation even under the situation of significant optical feedback.

  12. Pump element for a tube pump

    DEFF Research Database (Denmark)

    2011-01-01

    The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction rela...... to a part of the tube. The invention further relates to a method for creating a flow of a fluid within an at least partly flexible tube by means of a pump element as mentioned above.......The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction...... portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube...

  13. Tungstosilicic acid as an efficient catalyst for the one-pot multicomponent synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives under solvent-free conditions

    OpenAIRE

    Asadollah Hassankhani; Elaheh Mosaddegh; S.Yousef Ebrahimipour

    2016-01-01

    An efficient and environmentally benign protocol for the one-pot, three-component synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by condensation of dimedone, urazole, and aromatic aldehydes catalyzed by H4SiW12O40 as an ecofriendly catalyst with high catalytic activity and reusability at 100 °C under solvent-free conditions is reported. The reaction proceeds to completion within 20–70 min in 70–88% yield.

  14. Tungstosilicic acid as an efficient catalyst for the one-pot multicomponent synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives under solvent-free conditions

    Directory of Open Access Journals (Sweden)

    Asadollah Hassankhani

    2016-09-01

    Full Text Available An efficient and environmentally benign protocol for the one-pot, three-component synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by condensation of dimedone, urazole, and aromatic aldehydes catalyzed by H4SiW12O40 as an ecofriendly catalyst with high catalytic activity and reusability at 100 °C under solvent-free conditions is reported. The reaction proceeds to completion within 20–70 min in 70–88% yield.

  15. 小型脉冲光泵NH3分子远红外激光的Raman频谱研究%Study on Raman Spectrum of Miniature Pulsed Optically Pumped NH3 Fir Laser

    Institute of Scientific and Technical Information of China (English)

    冉勇; 李太全; 秦家银

    2001-01-01

    By solving the density matrix equation of quantum system,thespectral characteristics of V2:a→sR(0,0) and V2:a→sQ(5,4) transition in a miniature pulsed optically pumped NH3 far-infrared laser was calculated by means of iteration method.Which was pumped by TEA CO2-10R(6) line.The results of theoretical calculation showed that the spikes in raman spectrum of V2:a→sR(0,0) would appear,when the operating NH3 gas pressure was higher than a certain critical value or pumping power density was lower than a certain critical value.The spikes could not appear for spectrum of a→sQ(5,4)transition.Which was caused by raman processes interaction of AC Stark splitting.%通过求解量子系统的密度矩阵方程,采用迭代法计算了在TEACO2-10R(6)泵浦下,小型脉冲光泵NH3分子远红外激光器中,NH3分子的V2:a→sR(0,0)跃迁和a→sQ(5,4)跃迁的频谱特性。理论计算结果表明,对于a→sR(0,0)跃迁,当工作气压比临界值Pc高或泵功率密度比临界值Ipoc低时,将出现Raman频谱尖峰;对于a→sQ(5,4)跃迁,不出现频谱尖峰。频谱尖峰现象的根源是ACStark分裂的双光子相互作用的结果。

  16. Proton pump inhibitors

    Science.gov (United States)

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This ...

  17. New Class of Excimer-Pumped Atomic Lasers (XPALS)

    Science.gov (United States)

    2017-01-24

    appears to be scnlable in power but, more importBntly, the loser gain medium is cooled by the emission orevery laser photon. The smallest energy derect...during high power pumping has been performed. 15.SUBJECT TERMS alkali lasers , optical pumping, laser medium cooling 16. SECURITY CLASSIFICATION OF...critical to the cooling of the laser medium by pumping it through the lower lying states. Results obtained during this program were described in detail

  18. Pump for Saturated Liquids

    Science.gov (United States)

    Elliott, D. G.

    1986-01-01

    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

  19. High power resonant pumping of Tm-doped fiber amplifiers in core- and cladding-pumped configurations.

    Science.gov (United States)

    Creeden, Daniel; Johnson, Benjamin R; Rines, Glen A; Setzler, Scott D

    2014-11-17

    We have demonstrated ultra-high efficiency amplification in Tm-doped fiber with both core- and cladding-pumped configurations using a resonant tandem-pumping approach. These Tm-doped fiber amplifiers are pumped in-band with a 1908 nm Tm-doped fiber laser and operate at 1993 nm with >90% slope efficiency. In a core-pumped configuration, we have achieved 92.1% slope efficiency and 88.4% optical efficiency at 41 W output power. In a cladding-pumped configuration, we have achieved 123.1 W of output power with 90.4% optical efficiency and a 91.6% slope efficiency. We believe these are the highest optical efficiencies achieved in a Tm-doped fiber amplifier operating in the 2-micron spectral region.

  20. Theoretical Research of Terahertz Negative Dynamic Conductivity in Optically Pumped Graphene%光抽运石墨烯太赫兹负动态电导率的理论研究

    Institute of Scientific and Technical Information of China (English)

    张玉萍; 张晓; 刘陵玉; 张洪艳; 高营; 徐世林; 张会云

    2012-01-01

    石墨烯特殊的零带隙能带结构和载流子弛豫特性,在研究太赫兹辐射源相干放大领域引起广泛关注.考虑带内和带间跃迁对电导率的贡献,研究了光抽运单层和多层石墨烯中非平衡二维电子-空穴系统的动态电导率特性.结果表明,在足够强的光抽运下,石墨烯中的粒子数反转能够使得动态电导率的实部在太赫兹频段内出现负值,这使基于石墨烯的太赫兹放大或受激辐射源成为可能.同时,通过研究动量弛豫时间、温度、层数、光强对石墨烯的负动态电导率的影响表明,石墨烯多层结构的动态电导率最小值的绝对值更大,作为太赫兹激光器的激活介质更具优势.%Due to the gapless energy spectrum and carriers relaxation characteristics, graphene causes a widespread concern in amplification of terahertz coherent sources. We consider the contribution of both interband and intraband transitions to the conductivity, and study the dynamic conductivity characteristics of a nonequilibium two-dimensional electron-hole system in optically pumped single and multiple graphene layer (SGL and MGL) structures. The results demonstrate that the population inversion in graphene can lead to a negative dynamic conductivity in the terahertz range of frequencies at sufficiently strong pumping, and the phenomenon might be used in graphene-based terahertz coherent sources radiation and amplification. Meanwhile, by studying the dependences of the negative conductivity on momentum relaxation time, temperature, number of layers, and optical intensity, it is found that the minimum absolute value of the real part of conductivity in MGL structures is greater than that in SGL structures. Thus, the MGL structures have more advantages to be the active medium of terahertz laser.

  1. LD end-pumped acousto-optic Q-switched 1319 nm/1338 nm dual-wavelength Nd:YAG laser

    Science.gov (United States)

    Wu, C. T.; Yu, M.; Wang, C.; Yu, K.; Yu, Y. J.; Chen, X. Y.; Jin, G. Y.

    2016-10-01

    Laser characteristics of acousto-optic Q-switched operation of 1319 nm/1338 nm dual-wavelength composite Nd:YAG laser were studied. Maximum output power of 5.77 W was achieved in CW operation. Under Q-switched operation, the maximum peak power of 3.96 kW and minimum pulse width of 65.6 ns was obtained at repetition frequency of 20 kHz with the duty ratio of 96%. The influence of the duration of the ultrasonic field acted on the Q-switch to the output characteristics of dual-wavelength composite Nd:YAG laser had been reported first time.

  2. Vanadium-pumped titanium x-ray laser

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J.

    1991-02-13

    A resonantly photo-pumped x-ray laser is formed of a vanadium and titanium foil combination that is driven by two beams of intense line focused optical laser radiation. Ground state neon-like titanium ions are resonantly photo-pumped by line emission from fluorine-like vanadium ions.

  3. Monitoring DNAPL pumping using integrated geophysical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Newmark, R.L.

    1997-01-01

    The removal of DNAPL during pumping was monitored. At Hill AFB in Utah, a free-product DNAPL plume (predominantly TCE, with some TCA, PCE, methylene chloride) is pooled in water-wet soil on a thick clay aquitard. Groundwater pumping at Operable Unit 2 began in 1994; to date, nearly 30,000 gal DNAPL have been recovered. From Sept. 1994 through Sept. 1995, changes in the basin during DNAPL pumping were monitored using fiber optic chemical sensors, neutron logs, and electrical resistance tomography (ERT). The first two sensor types verify the presence of DNAPL in vicinity of 3 boreholes which form a cross section from the perimeter of the basin to its center. Cross borehole ERT images the changes in formation electrical properties due to removal of DNAPL, extending the understanding of DNAPL removal between the boreholes. During pumping, electrical resistivities decreased; we suggest these decreases are directly caused by the reduction in DNAPL. During ground water pumping, water with relatively low resistivity replaces some of the DNAPL pockets as the highly insulating DNAPL is removed. Results suggest that, as DNAPL is pumped from a nearby well, product slowly drains along the top of an aquitard and into the pump well, where it collects.

  4. Intracavity interferometry using synchronously pumped OPO

    Science.gov (United States)

    Zavadilová, Alena; Vyhlídal, David; Kubeček, Václav; Šulc, Jan; Navrátil, Petr

    2016-12-01

    The concept of system for intracavity interferometry based on the beat note detection in subharmonic synchronously intracavity pumped optical parametrical oscillator (OPO) is presented. The system consisted of SESAM-modelocked, picosecond, diode pumped Nd:YVO4 laser, operating at wavelength 1.06 μm and tunable linear intracavity pumped OPO based on MgO:PPLN crystal, widely tunable in 1.5 μm able to deliver two independent trains of picosecond pulses. The optical length of the OPO cavity was set to be exactly twice the pumping cavity length. In this configuration the OPO produces signal pulses with the same repetition frequency as the pump laser but the signal consists of two completely independent pulse trains. For purpose of pump probe measurements the setup signal with half repetition rate and scalable amplitude was derived from the OPO signal using RF signal divider, electropotical modulator and fiber amplifier. The impact of one pump beam on the sample is detected by one probing OPO train, the other OPO train is used as a reference. The beat note measured using the intracavity interferometer is proportional to phase modulation caused by the pump beam. The bandwidth of observed beat-note was less than 1 Hz (FWHM), it corresponds to a phase shift measurement error of less than 1.5 × 10-7 rad without any active stabilization. Such compact low-cost system could be used for ultra-sensitive phase-difference measurements (e.g. nonlinear refractive index measurement) for wide range of material especially in spectral range important for telecom applications.

  5. Optical and opto-electronic characterization of semiconducting nanostructures; Optische und optoelektronische Charakterisierung von halbleitenden Nanostrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Offer, Matthias

    2011-10-12

    In the present thesis, the photoluminescence (PL) of cadmium selenide nanoparticles and doped gallium arsenide nanowires are investigated. Furthermore, in GaAs nanowires, with a distinct pn-junction in the direction of growth, electroluminescence (EL) is demonstrated and analyzed for the fist time. Using PL spectroscopy, the excitonic states of individual CdSe nanoparticles are studied. Sharp emission lines, which can be assigned to different excitonic transitions, can be observed. At a sample temperature of T{approx_equal}10 K, line widths of {delta}E{sub FWHM} {<=}8 meV are found. Additionally, it is demonstrated that, apart from the main line, phonon replica of the LO and 2LO-phonon can be observed. An exciton in an ionized nanoparticle has the electronic structure of a trion. In silicon, the recombination of a trion in CdSe nanoparticles, while optically allowed, will not be detected visually because faster non-radiative Auger processes dominate (off-state). However, this work shows that, on a coated aluminium alloy substrate, the trions of single CdSe nanoparticles are observable. This observation is due to the reduction of the optical lifetime and is caused by surface plasmons. Instead of the commonly occurring off-state, a jump-like and discrete red shift of the emission energy of {delta}E {approx}24 meV is observed. This emission line can also be attributed to a negative trion. In addition, p- and n-doped GaAs nanowires are characterized using spatially resolved PL spectroscopy. The intrinsic stump of the nanowire shows the typical PL of GaAs. Through doping of the GaAs nanowire, there is a recognizable shift in the emission energy. This shift can be attributed to increasing dopant concentration. By analyzing the line shape, information regarding the distribution and concentration of the dopant can be found. Using these findings, the PL of a single GaAs nanowire with a distinct pn-junction in the direction of growth is examined. This observation shows that

  6. Interactions between xenon and phospholipid bicelles studied by 2H/ 129Xe/ 131Xe NMR and optical pumping of nuclear spins

    Science.gov (United States)

    Li, Xiaoxia; Newberry, Caitlin; Saha, Indrajit; Nikolaou, Panayiotis; Whiting, Nicholas; Goodson, Boyd M.

    2006-02-01

    The interactions between xenon and DMPC/DHPC bicelles ( q = 3.5%, 7.5% w/v) were studied via 2H, 129Xe, 131Xe, and optically enhanced 129Xe NMR. The chemical shifts, linewidths, and quadrupolar couplings of the xenon/bicelle NMR signals were correlated with different regions of the bicellar phase diagram. The addition of xenon (<70 mM) was observed to reduce the temperature-onset of bicelle alignment by several degrees, in quantitative agreement with effects previously observed with chloroform; however, the stable liquid-crystalline range was not significantly reduced. Preliminary laser-polarized xenon/bicelle studies yielded 129Xe T1 values of ˜120 s, long enough to permit a variety of planned experiments.

  7. Waveguide mutually pumped phase conjugators

    OpenAIRE

    James, S. W.; Youden, K.E.; Jeffrey, P. M.; EASON, R. W.; Chandler, P.J.; Zhang, L.; Townsend, P.D.

    1993-01-01

    The operation of the Bridge Mutually Pumped Phase Conjugator is reported in a planar waveguide structure in photorefractive BaTiO3. The waveguide was fabricated by the technique of ion implantation. using 1.5 MeV H+ at a dose of 10^16 ions/cm^2. An order of magnitude decrease in response time is observed in the waveguide as compared to typical values obtained in bulk crystals, probably resulting from a combination of the optical confinement within the waveguide, and possibly modification of t...

  8. Optically pumped 1.3  μm room-temperature InAs quantum-dot micro-disk lasers directly grown on (001) silicon.

    Science.gov (United States)

    Wan, Yating; Li, Qiang; Liu, Alan Y; Gossard, Arthur C; Bowers, John E; Hu, Evelyn L; Lau, Kei May

    2016-04-01

    Direct integration of high-performance laser diodes on silicon will dramatically transform the world of photonics, expediting the progress toward low-cost and compact photonic integrated circuits (PICs) on the mainstream silicon platform. Here, we report, to the best of our knowledge, the first 1.3 μm room-temperature continuous-wave InAs quantum-dot micro-disk lasers epitaxially grown on industrial-compatible Si (001) substrates without offcut. The lasing threshold is as low as hundreds of microwatts, similar to the thresholds of identical lasers grown on a GaAs substrate. The heteroepitaxial structure employed here does not require the use of an absorptive germanium buffer and/or dislocation filter layers, both of which impede the efficient coupling of light from the laser active regions to silicon waveguides. This allows for full compatibility with the extensive silicon-on-insulator (SOI) technology. The large-area virtual GaAs (on Si) substrates can be directly adopted in various mature in-plane laser configurations, both optically and electrically. Thus, this demonstration represents a major advancement toward the commercial success of fully integrated silicon photonics.

  9. LED pumped micron-scale all-silicon Raman amplifier

    Science.gov (United States)

    Datta, Tanmoy; Sen, Mrinal

    2017-10-01

    A micron-scale all-silicon Raman amplifier has been proposed in this paper, exploiting the giant Raman gain of silicon nanocrystal material along with the extreme optical confinement of slotted photonic crystal waveguide. Light Emitting Diode (LED) has been considered here for low-cost optical pumping and the possibility of on-chip integration. At the same time, LED pumping eradicates the temporal impairment of output pulses which is otherwise unavoidable in case of continuous wave laser pumping. An overall gain of 3.22 dB has been achieved for a 400 Gbps input pulse train with a waveguide length of the amplifier which is as small as 4 μm. Moreover, the strong electroluminescence of silicon nanocrystal opens up the possibility of integrating the pump source on the same platform and, hence, expedites the future scope of realizing micron-scale silicon Raman laser without external pump source.

  10. High-Efficiency High-Power Nd:YAG Laser under 885 nm Laser Diode Pumping

    Institute of Scientific and Technical Information of China (English)

    LI Fang-Qin; ZHANG Xiao-Fu; ZONG Nan; YANG Jing; PENG Qin-Jun; CUI Da-Fu; XU Zu-Yan

    2009-01-01

    A high-efficiency high-power Nd:YAG laser under 885 nm laser diode (LD) pumping is demonstrated. The laser crystal is carefully designed, and the overlapping between the pump modes and the laser modes is optimized. The maximum output power at 1064 nm is 87 W under the absorbed pump power 127.7 W, corresponding to a slope efficiency of 72.4% and an optical-optical efficiency of 68.1%. The optical-optical efficiency is 58.4% for the pump power emitted directly from the LD. To our best knowledge, this is the maximal optical-optical conversion efficiency obtained for the LD end-pumped Nd:YAG lasers so far.

  11. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  12. Spectral and Dynamical Properties of Single Excitons, Biexcitons, and Trions in Cesium-Lead-Halide Perovskite Quantum Dots.

    Science.gov (United States)

    Makarov, Nikolay S; Guo, Shaojun; Isaienko, Oleksandr; Liu, Wenyong; Robel, István; Klimov, Victor I

    2016-04-13

    Organic-inorganic lead-halide perovskites have been the subject of recent intense interest due to their unusually strong photovoltaic performance. A new addition to the perovskite family is all-inorganic Cs-Pb-halide perovskite nanocrystals, or quantum dots, fabricated via a moderate-temperature colloidal synthesis. While being only recently introduced to the research community, these nanomaterials have already shown promise for a range of applications from color-converting phosphors and light-emitting diodes to lasers, and even room-temperature single-photon sources. Knowledge of the optical properties of perovskite quantum dots still remains vastly incomplete. Here we apply various time-resolved spectroscopic techniques to conduct a comprehensive study of spectral and dynamical characteristics of single- and multiexciton states in CsPbX3 nanocrystals with X being either Br, I, or their mixture. Specifically, we measure exciton radiative lifetimes, absorption cross-sections, and derive the degeneracies of the band-edge electron and hole states. We also characterize the rates of intraband cooling and nonradiative Auger recombination and evaluate the strength of exciton-exciton coupling. The overall conclusion of this work is that spectroscopic properties of Cs-Pb-halide quantum dots are largely similar to those of quantum dots of more traditional semiconductors such as CdSe and PbSe. At the same time, we observe some distinctions including, for example, an appreciable effect of the halide identity on radiative lifetimes, considerably shorter biexciton Auger lifetimes, and apparent deviation of their size dependence from the "universal volume scaling" previously observed for many traditional nanocrystal systems. The high efficiency of Auger decay in perovskite quantum dots is detrimental to their prospective applications in light-emitting devices and lasers. This points toward the need for the development of approaches for effective suppression of Auger

  13. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed.

  14. Champagne Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    2004-01-01

    The term champagne heat pump denotes a developmental heat pump that exploits a cycle of absorption and desorption of carbon dioxide in an alcohol or other organic liquid. Whereas most heat pumps in common use in the United States are energized by mechanical compression, the champagne heat pump is energized by heating. The concept of heat pumps based on other absorption cycles energized by heat has been understood for years, but some of these heat pumps are outlawed in many areas because of the potential hazards posed by leakage of working fluids. For example, in the case of the water/ammonia cycle, there are potential hazards of toxicity and flammability. The organic-liquid/carbon dioxide absorption/desorption cycle of the champagne heat pump is similar to the water/ammonia cycle, but carbon dioxide is nontoxic and environmentally benign, and one can choose an alcohol or other organic liquid that is also relatively nontoxic and environmentally benign. Two candidate nonalcohol organic liquids are isobutyl acetate and amyl acetate. Although alcohols and many other organic liquids are flammable, they present little or no flammability hazard in the champagne heat pump because only the nonflammable carbon dioxide component of the refrigerant mixture is circulated to the evaporator and condenser heat exchangers, which are the only components of the heat pump in direct contact with air in habitable spaces.

  15. Resonance wave pumping: wave mass transport pumping

    Science.gov (United States)

    Carmigniani, Remi; Violeau, Damien; Gharib, Morteza

    2016-11-01

    It has been previously reported that pinching at intrinsic resonance frequencies a valveless pump (or Liebau pump) results in a strong pulsating flow. A free-surface version of the Liebau pump is presented. The experiment consists of a closed tank with a submerged plate separating the water into a free-surface and a recirculation section connected through two openings at each end of the tank. A paddle is placed at an off-centre position at the free-surface and controlled in a heaving motion with different frequencies and amplitudes. Near certain frequencies identified as resonance frequencies through a linear potential theory analysis, the system behaves like a pump. Particle Image Velocimetry (PIV) is performed in the near free surface region and compared with simulations using Volume of Fluid (VOF) method. The mean eulerian mass flux field (ρ) is extracted. It is observed that the flow is located in the vicinity of the surface layer suggesting Stokes Drift (or Wave Mass Transport) is the source of the pumping. A model is developped to extend the linear potential theory to the second order to take into account these observations. The authors would like to acknowledge the Gordon and Betty Moore Foundation for their generous support.

  16. Development of a surface micromachined spiral-channel viscous pump

    Science.gov (United States)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  17. Current Injection Pumping of Organic Light Emitters

    Science.gov (United States)

    1989-09-28

    MOT-OOO1AF I Current Injection Pumping of Organic Light Emitters Prepared by DI Jeffrey C. Buchholz E L ri: 8 James P. Stec OCT C "t989 Mary C...Schutte Micro -Optics Technologies, Inc. 8608 University Green #5 Middleton, WI 53562 28 September 1989 D,:?UqflON SA2". N’.’ _ Disuibunon Uanu-ted Contract...Title Report Date Current Injection Pumping of Organic Light Emitters 28 September 1989 Authors Jeffrey C. Buchholz, James P. Stec, Mary C. Schutte

  18. Demanding pump power; Krevende pumpekraft

    Energy Technology Data Exchange (ETDEWEB)

    Lie, Oeyvind

    2011-07-01

    The potential for pump power in Norway is huge, but it is difficult to exploit it. Norway has some pumping plants, but these are built for seasonal pumping (pumping up to the magazine in the summer, and production in the winter). Pump power plants for short periods do not exist in Norway. (AG)

  19. 光抽运多层石墨烯太赫兹表面等离子体增益特性的研究%Study on the gain characteristics of terahertz surface plasma in optically pump ed graphene multi-layer structures

    Institute of Scientific and Technical Information of China (English)

    刘亚青; 张玉萍; 张会云; 吕欢欢; 李彤彤; 任广军

    2014-01-01

    本文建立了光抽运多层石墨烯表面等离子体模型,计算了光抽运多层石墨烯等离子体传播系数的实部和吸收系数,讨论了动量弛豫时间、温度、层数、准费米能级对表面等离子体传播系数的实部和吸收系数的影响。研究结果表明,光抽运多层石墨烯使其动态电导率的实部在太赫兹频段内出现负值时,石墨烯表面等离子体实现增益。通过光抽运剥离层石墨烯和含有底层石墨烯结构表面等离子体传播系数和吸收系数比较,表明光抽运剥离层石墨烯能更有效地实现表面等离子体的增益。同时,在低温下,光抽运具有合适层数的石墨烯比光抽运单层石墨烯能获得更大的表面等离子体增益。%Based on the developed optically pumped graphene multilayer terahertz surface plasma structures, this paper calculates the real part of propagation index and amplification coefficient in optically pumped graphene multilayer structures, discusses the influences of momentum relaxation time, temperature, numbers of grapheme layers, and the quasi-Fermi energy in the topmost grapheme layer on the real part of propagation index and amplification coefficient. It is shown that when the real part of dynamic conductivity becomes negative in the terahertz range of frequencies in the optically pumped graphene multilayer structures, the surface plasma of graphene layers can achieve gain. By comparing the peeling-graphene-structure with the graphene structure that has a high conducting bottom graphene layer in optically pumped scheme, it can be said that the surface plasma of the peeling-graphene-structure can get a high efficient amplification. Meanwhile, the structure having properly numbers of graphene layers can get a larger amplification than the single graphene structure in an optically pumped scheme at low temperatures.

  20. Pump element for a tube pump

    DEFF Research Database (Denmark)

    2011-01-01

    relative to the rod element so as to allow for a fluid flow in the tube through the first valve member, along the rod element, and through the second valve member. The tube comprises an at least partly flexible tube portion between the valve members such that a repeated deformation of the flexible tube...... portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube...... pump as mentioned above, thereby acting to generate a fluid flow through the tube upon repeated deformation of the tube between the two valve members. The pump element may comprise a connecting part for coupling to another tube and may comprise a sealing part establishing a fluid tight connection...

  1. Dynamic properties of single pump, dispersion-compensating Raman/EDFA hybrid amplifier recycling residual Raman pump.

    Science.gov (United States)

    Lee, Ju; Chang, You; Han, Young-Geun; Kim, Sang; Lee, Sang

    2004-12-27

    We experimentally investigate transient effects of our proposed single pump, dispersion-compensating Raman/EDFA hybrid amplifier recycling residual Raman pump in a cascaded EDF under the situation of multi-channel add/drop, and then demonstrate the use of a FBG based all-optical gain-clamping technique to efficiently suppress the output transients. The results show that the proposed hybrid amplifier has a significantly long transient response time of ~ 2 ms compared to the previous reported value of the conventional separate pump, Raman/EDFA hybrid amplifiers due to both the low-pumping regime operation of 14XX nm pumped EDFA section and the additional pump transit time through the 12.6 km long dispersion compensating fiber to reach the EDF. However, using a simple gain-clamping method we obtain an almost, transient-free operation.

  2. Role of hyperfine interaction on electron spin optical orientation in charge-controlled InAs-GaAs single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, O.; Eble, B.; Lemaitre, A.; Kudelski, A.; Voisin, P. [Laboratoire de Photonique et Nanostructures-CNRS, Route de Nozay, 91460 Marcoussis (France); Urbaszek, B.; Marie, X.; Amand, T. [Laboratoire de Nanophysique Magnetisme et Optoelectronique, INSA, 31077 Toulouse Cedex 4 (France); Kowalik, K. [Laboratoire de Photonique et Nanostructures-CNRS, Route de Nozay, 91460 Marcoussis (France); Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw (Poland)

    2007-01-15

    We report on electron spin physics in a single charge-tunable self-assembled InAs/GaAs quantum dot. The hyperfine interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser-shift depends on the trion state X{sup +} or X{sup -}, and remarkably its strength does not vanish in zero magnetic field. This explains the quenching of X{sup +} spin relaxation under steady-state excitation polarization. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. 407 W End-pumped Multi-segmented Nd:YAG Laser.

    Science.gov (United States)

    Kracht, Dietmar; Wilhelm, Ralf; Frede, Maik; Dupré, Klaus; Ackermann, Lothar

    2005-12-12

    A composite crystalline Nd:YAG rod consisting of 5 segments with different dopant concentrations for high power diode end-pumping is presented. A maximum laser output power of 407 W with an optical-to-optical efficiency of 54 % was achieved by longitudinal pumping with a high power laser diode stack.

  4. Diode Stack End-Pumped Nd:GdVO4 Continuous Wave Slab Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-Li; ZHANG Huai-Jin; LI Dai-Jun; WANG Ji-Yang; SHI Peng; Haas Rüdiger; LI Hong-Xia; JIANG Min-Hua; DU Keming

    2005-01-01

    @@ We report a diode stack end-pumped Nd:GdVO4 slab laser with a near-diffraction-limited beam. The output power of 45.8 W at 1064nm is obtained under the pumping power of 147W, with the optical-optical conversion efficiency of 31.2%, and the slope efficiency is 39.6%.

  5. Efficient Ho:YLF laser pumped by a Tm:fiber laser

    CSIR Research Space (South Africa)

    Koen, W

    2013-10-01

    Full Text Available A thulium fiber laser pumped Ho:YLF laser delivering 45.1 W in a near diffraction limited beam when pumped with 84.7 W is demonstrated. The optical-to-optical efficiency of 53 % compares favorably with similar Ho:YAG lasers....

  6. A Shocking New Pump

    Science.gov (United States)

    2000-01-01

    Hydro Dynamics, Inc. received a technical helping hand from NASA that made their Hydrosonic Pump (HPump) a reality. Marshall engineers resolved a bearing problem in the rotor of the pump and recommended new bearings, housings and mounting hardware as a solution. The resulting HPump is able to heat liquids with greater energy efficiency using shock waves to generate heat.

  7. Water Treatment Technology - Pumps.

    Science.gov (United States)

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on pumps provides instructional materials for three competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: types of pumps in plant and distribution systems, pump…

  8. Review of magnetohydrodynamic pump applications

    National Research Council Canada - National Science Library

    Al-Habahbeh, O.M; Al-Saqqa, M; Safi, M; Abo Khater, T

    2016-01-01

    Magneto-hydrodynamic (MHD) principle is an important interdisciplinary field. One of the most important applications of this effect is pumping of materials that are hard to pump using conventional pumps...

  9. Dichroic mirror for diode pumped YAG:Nd-laser

    DEFF Research Database (Denmark)

    Dinca, Andreea; Skettrup, Torben; Lupei, V.

    1996-01-01

    The paper describes the design and realization of a dichroic mirror for a diode pumped YAG:Nd laser. The mirror is deposed on an optical glass substrate and works in optical contact with the laser crystal. The design was performed by admittance matching of the basic stack with the adjacent media...

  10. Pumping machinery theory and practice

    CERN Document Server

    Badr, Hassan M

    2014-01-01

    Pumping Machinery Theory and Practice comprehensively covers the theoretical foundation and applications of pumping machinery. Key features: Covers characteristics of centrifugal pumps, axial flow pumps and displacement pumpsConsiders pumping machinery performance and operational-type problemsCovers advanced topics in pumping machinery including multiphase flow principles, and two and three-phase flow pumping systemsCovers different methods of flow rate control and relevance to machine efficiency and energy consumptionCovers different methods of flow rate control and relevance to machine effi

  11. Optical control of exciton states and enhanced valley Zeeman splitting in WS2(Conference Presentation)

    Science.gov (United States)

    Kioseoglou, George; Currie, Marc; Hanbicki, Aubrey T.; Paradisanos, Ioannis; Stratakis, Emmanuel; Fotakis, Costas; Jonker, Berrend T.

    2016-10-01

    Monolayer transition metal dichalcogenides, MX2 (M = Mo, W and X = S, Se), are direct-gap semiconductors with many interesting properties capable of producing an all-surface material applicable to sensing, single-atom storage and other quantum-based technologies. Here we report on the optical control of single layers of MX2 such that the photoluminescence (PL) is solely from the trion state. After trion isolation, changes in the Raman spectra were observed: there is a decrease in the intensity of the out of plane mode and an enhancement of the 2LA mode. The effect is reversible, and our results suggest that the changes of the strength of a particular excitonic state are due to surface interactions with ambient environment. In addition, spatial non-uniformity is probed by studying variations of strain and the PL emission as a function of position on our sample. The boundaries of mechanically exfoliated MX2 as well as boundaries intentionally created via fs laser ablation were investigated. The edges exhibit significant Raman shifts as well as remarkably enhanced PL emission compared to their respective central area. Finally, we probe the degree of circular polarization of the emitted PL as a function of the photo-excitation energy and temperature to elucidate spin-dependent inter- and intra-valley relaxation mechanisms. This work was supported by the FP7-REGPOT-2012-2013-1, under grant agreement 316165.

  12. Nuclear-pumped lasers

    CERN Document Server

    Prelas, Mark

    2016-01-01

    This book focuses on Nuclear-Pumped Laser (NPL) technology and provides the reader with a fundamental understanding of NPLs, a review of research in the field, and exploration of large scale NPL system design and applications. Early chapters look at the fundamental properties of lasers, nuclear-pumping and nuclear reactions that may be used as drivers for nuclear-pumped lasers. The book goes on to explore the efficient transport of energy from the ionizing radiation to the laser medium and then the operational characteristics of existing nuclear-pumped lasers. Models based on Mathematica, explanations and a tutorial all assist the reader’s understanding of this technology. Later chapters consider the integration of the various systems involved in NPLs and the ways in which they can be used, including beyond the military agenda. As readers will discover, there are significant humanitarian applications for high energy/power lasers, such as deflecting asteroids, space propulsion, power transmission and mining....

  13. Absorption heat pump system

    Science.gov (United States)

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  14. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  15. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  16. Underground pumped hydroelectric storage

    Science.gov (United States)

    Allen, R. D.; Doherty, T. J.; Kannberg, L. D.

    1984-07-01

    Underground pumped hydroelectric energy storage was conceived as a modification of surface pumped storage to eliminate dependence upon fortuitous topography, provide higher hydraulic heads, and reduce environmental concerns. A UPHS plant offers substantial savings in investment cost over coal-fired cycling plants and savings in system production costs over gas turbines. Potential location near load centers lowers transmission costs and line losses. Environmental impact is less than that for a coal-fired cycling plant. The inherent benefits include those of all pumped storage (i.e., rapid load response, emergency capacity, improvement in efficiency as pumps improve, and capacity for voltage regulation). A UPHS plant would be powered by either a coal-fired or nuclear baseload plant. The economic capacity of a UPHS plant would be in the range of 1000 to 3000 MW. This storage level is compatible with the load-velocity requirements of a greater metropolitan area with population of 1 million or more.

  17. Chiral brownian heat pump.

    Science.gov (United States)

    van den Broek, M; Van den Broeck, C

    2008-04-04

    We present the exact analysis of a chiral Brownian motor and heat pump. Optimization of the construction predicts, for a nanoscale device, frequencies of the order of kHz and cooling rates of the order of femtojoule per second.

  18. Chiral Brownian heat pump

    OpenAIRE

    Van Den Broek, Martijn; Van Den Broeck, Christian

    2007-01-01

    We present the exact analysis of a chiral Brownian motor and heat pump. Optimization of the construction predicts, for a nanoscale device, frequencies of the order of kHz and cooling rates of the order of femtojoule per second.

  19. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  20. Phonon Cooling by an Optomechanical Heat Pump.

    Science.gov (United States)

    Dong, Ying; Bariani, F; Meystre, P

    2015-11-27

    We propose and analyze theoretically a cavity optomechanical analog of a heat pump that uses a polariton fluid to cool mechanical modes coupled to a single precooled phonon mode via external modulation of the substrate of the mechanical resonator. This approach permits us to cool phonon modes of arbitrary frequencies not limited by the cavity-optical field detuning deep into the quantum regime from room temperature.

  1. Remotely Adjustable Hydraulic Pump

    Science.gov (United States)

    Kouns, H. H.; Gardner, L. D.

    1987-01-01

    Outlet pressure adjusted to match varying loads. Electrohydraulic servo has positioned sleeve in leftmost position, adjusting outlet pressure to maximum value. Sleeve in equilibrium position, with control land covering control port. For lowest pressure setting, sleeve shifted toward right by increased pressure on sleeve shoulder from servovalve. Pump used in aircraft and robots, where hydraulic actuators repeatedly turned on and off, changing pump load frequently and over wide range.

  2. Lunar Base Heat Pump

    Science.gov (United States)

    Walker, D.; Fischbach, D.; Tetreault, R.

    1996-01-01

    The objective of this project was to investigate the feasibility of constructing a heat pump suitable for use as a heat rejection device in applications such as a lunar base. In this situation, direct heat rejection through the use of radiators is not possible at a temperature suitable for lde support systems. Initial analysis of a heat pump of this type called for a temperature lift of approximately 378 deg. K, which is considerably higher than is commonly called for in HVAC and refrigeration applications where heat pumps are most often employed. Also because of the variation of the rejection temperature (from 100 to 381 deg. K), extreme flexibility in the configuration and operation of the heat pump is required. A three-stage compression cycle using a refrigerant such as CFC-11 or HCFC-123 was formulated with operation possible with one, two or three stages of compression. Also, to meet the redundancy requirements, compression was divided up over multiple compressors in each stage. A control scheme was devised that allowed these multiple compressors to be operated as required so that the heat pump could perform with variable heat loads and rejection conditions. A prototype heat pump was designed and constructed to investigate the key elements of the high-lift heat pump concept. Control software was written and implemented in the prototype to allow fully automatic operation. The heat pump was capable of operation over a wide range of rejection temperatures and cooling loads, while maintaining cooling water temperature well within the required specification of 40 deg. C +/- 1.7 deg. C. This performance was verified through testing.

  3. Gain Characteristics of Fiber Optical Parametric Amplifier

    Institute of Scientific and Technical Information of China (English)

    高明义; 姜淳; 胡卫生

    2004-01-01

    The theory model of fiber optical parametric amplifier (FOPA) was introduced, which is based on optical nonlinear effect. And then numerical simulation was done to analyze and discuss the gain spectral characteristics of one-pump and two-pump FOPA. The results show that for one-pump FOPA, when pump wavelength is near to fiber zero-dispersion wavelength(ZDW), the gain flatness is better, and with the increase of the pump power, fiber length and its nonlinear coefficient, the gain value will increase while the gain bandwidth will become narrow. For two-pump FOPA, when the pump central wavelength is near to fiber ZDW, the gain flatness is better. Moreover, by decreasing the space of two pumps wavelength, the gain flatness can be improved. Finally, some problems existing in FOPA were addressed.

  4. BIOMATERIALS FOR ROTARY BLOOD PUMPS

    NARCIS (Netherlands)

    VANOEVEREN, W

    1995-01-01

    Rotary blood pumps are used for cardiac assist and cardiopulmonary support since mechanical blood damage is less than with conventional roller pumps. The high shear rate in the rotary pump and the reduced anticoagulation of the patient during prolonged pumping enforces high demands on the biocompati

  5. Pumping a playground swing.

    Science.gov (United States)

    Post, Auke A; de Groot, Gert; Daffertshofer, Andreas; Beek, Peter J

    2007-04-01

    In mechanical studies of pumping a playground swing, two methods of energy insertion have been identified: parametric pumping and driven oscillation. While parametric pumping involves the systematic raising and lowering of the swinger's center of mass (CM) along the swing's radial axis (rope), driven oscillation may be conceived as rotation of the CM around a pivot point at a fixed distance to the point of suspension. We examined the relative contributions of those two methods of energy insertion by inviting 18 participants to pump a swing from standstill and by measuring and analyzing the swing-swinger system (defined by eight markers) in the sagittal plane. Overall, driven oscillation was found to play a major role and parametric pumping a subordinate role, although the relative contribution of driven oscillation decreased as swinging amplitude increased, whereas that of parametric pumping increased slightly. Principal component analysis revealed that the coordination pattern of the swing-swinger system was largely determined (up to 95%) by the swing's motion, while correlation analysis revealed that (within the remaining 5% of variance) trunk and leg rotations were strongly coupled.

  6. Transient Effects And Pump Depletion In Stimulated Raman Scattering

    Science.gov (United States)

    Carlsten, J. L.; Wenzel, R. G...; Druhl, K.

    1983-11-01

    Stimulated rotational Raman scattering in a 300-K multipass cell filled with para-H2 with a single-mode CO2-pumped laser is studied using a frequency-narrowed optical parametric oscillator (OPO) as a probe laser at the Stokes frequency for the So(0) transition. Amplification and pump depletion are examined as a function of incident pump energy. The pump depletion shows clear evidence of transient behavior. A theoretical treatment of transient stimulated Raman scattering, including effects of both pump depletion and medium saturation is presented. In a first approximation, diffraction effects are neglected, and only plane-wave interactions are considered. The theoretical results are compared to the experimental pulse shapes.

  7. Ultra-broadband infrared pump-probe spectroscopy using synchrotron radiation and a tuneable pump

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Lee; Friedli, Peter; Stutz, Stefan; Sigg, Hans [Laboratory for Micro and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Lerch, Philippe; Schneider, Joerg; Treyer, Daniel; Hunziker, Stephan [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2011-06-15

    Synchrotron infrared sources have become popular mainly because of their excellent broadband brilliance, which enables spectroscopically resolved spatial-mapping of stationary objects at the diffraction limit. In this article we focus on an often-neglected further advantage of such sources - their unique time-structure - to bring such broadband spectroscopy to the time domain, for studying dynamic phenomenon down to the 100 ps limit. We describe the ultra-broadband (12.5 to 1.1 {mu}m) Fourier transform pump-probe setup, for condensed matter transmission- and reflection-spectroscopy, installed at the X01DC infrared beam-line of the Swiss Light Source (SLS). The optical pump consists of a widely tuneable 100 ps 1 kHz laser system, covering 94% of the 16 to 1.1 {mu}m range. A thorough description of the system is given, including (i) the vector-modulator providing purely electronic tuning of the pump-probe overlap up to 1 ms with sub-ps time resolution, (ii) the 500 MHz data acquisition system interfaced with the experimental physics and industrial control system (EPICS) based SLS control system for consecutive pulse sampling, and (iii) the step-scan time-slice Fourier transform scheme for simultaneous recording of the dual-channel pumped, un-pumped, and difference spectra. The typical signal/noise ratio of a single interferogram in a 100 ps time slice is 300 (measured during one single 140 s TopUp period). This signal/noise ratio is comparable to that of existing gated Globar pump-probe Fourier transform spectroscopy, but brings up to four orders of magnitude better time resolution. To showcase the utility of broadband pump-probe spectroscopy, we investigate a Ge-on-Si material system similar to that in which optically pumped direct-gap lasing was recently reported. We show that the mid-infrared reflection-spectra can be used to determine the optically injected carrier density, while the mid- and near-infrared transmission-spectra can be used to separate the strong

  8. Ultra-broadband infrared pump-probe spectroscopy using synchrotron radiation and a tuneable pump.

    Science.gov (United States)

    Carroll, Lee; Friedli, Peter; Lerch, Philippe; Schneider, Jörg; Treyer, Daniel; Hunziker, Stephan; Stutz, Stefan; Sigg, Hans

    2011-06-01

    Synchrotron infrared sources have become popular mainly because of their excellent broadband brilliance, which enables spectroscopically resolved spatial-mapping of stationary objects at the diffraction limit. In this article we focus on an often-neglected further advantage of such sources - their unique time-structure - to bring such broadband spectroscopy to the time domain, for studying dynamic phenomenon down to the 100 ps limit. We describe the ultra-broadband (12.5 to 1.1 μm) Fourier transform pump-probe setup, for condensed matter transmission- and reflection-spectroscopy, installed at the X01DC infrared beam-line of the Swiss Light Source (SLS). The optical pump consists of a widely tuneable 100 ps 1 kHz laser system, covering 94% of the 16 to 1.1 μm range. A thorough description of the system is given, including (i) the vector-modulator providing purely electronic tuning of the pump-probe overlap up to 1 ms with sub-ps time resolution, (ii) the 500 MHz data acquisition system interfaced with the experimental physics and industrial control system (EPICS) based SLS control system for consecutive pulse sampling, and (iii) the step-scan time-slice Fourier transform scheme for simultaneous recording of the dual-channel pumped, un-pumped, and difference spectra. The typical signal/noise ratio of a single interferogram in a 100 ps time slice is 300 (measured during one single 140 s TopUp period). This signal/noise ratio is comparable to that of existing gated Globar pump-probe Fourier transform spectroscopy, but brings up to four orders of magnitude better time resolution. To showcase the utility of broadband pump-probe spectroscopy, we investigate a Ge-on-Si material system similar to that in which optically pumped direct-gap lasing was recently reported. We show that the mid-infrared reflection-spectra can be used to determine the optically injected carrier density, while the mid- and near-infrared transmission-spectra can be used to separate the strong pump

  9. Efficient potassium diode pumped alkali laser operating in pulsed mode.

    Science.gov (United States)

    Zhdanov, Boris V; Rotondaro, Matthew D; Shaffer, Michael K; Knize, Randall J

    2014-07-14

    This paper presents the results of our experiments on the development of an efficient hydrocarbon free diode pumped alkali laser based on potassium vapor buffered by He gas at 600 Torr. A slope efficiency of more than 50% was demonstrated with a total optical conversion efficiency of 30%. This result was achieved by using a narrowband diode laser stack as the pump source. The stack was operated in pulsed mode to avoid limiting thermal effects and ionization.

  10. 600-W lamp pumped CW Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Qiang Li(李强); Zhimin Wang(王志敏); Zhiyong Wang(王智勇); Zhensheng Yu(于振声); Hong Lei(雷訇); Jiang Guo(郭江); Gang Li(李港); Tiechuan Zuo(左铁钏)

    2003-01-01

    A lamp pumped CW Nd:YAG laser is presented in this paper for the requirement of industrial application.The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analyzed. Total electro-optics efficiency of lamp pumped Nd:YAG crystal as high as 4.0% is obtained, and output power is higher than 647 W with beam parameter product 22 mm.mrad.

  11. Pump-probe imaging of historical pigments used in paintings.

    Science.gov (United States)

    Samineni, Prathyush; deCruz, Adele; Villafaña, Tana E; Warren, Warren S; Fischer, Martin C

    2012-04-15

    A recently developed nonlinear optical pump-probe microscopy technique uses modulation transfer to sensitively extract excited-state dynamics of endogenous biological pigments, such as eumelanin and pheomelanin. In this work, we use this method to image and characterize several inorganic and organic pigments used in historical art. We show substantial differences in the near-IR pump-probe signatures from nominally similar pigments and suggest extensions to art restoration.

  12. Method and system for homogenizing diode laser pump arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, Andrew James

    2016-05-03

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  13. Thermally Actuated Hydraulic Pumps

    Science.gov (United States)

    Jones, Jack; Ross, Ronald; Chao, Yi

    2008-01-01

    Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

  14. Radio pumping of ionospheric plasma with orbital angular momentum.

    Science.gov (United States)

    Leyser, T B; Norin, L; McCarrick, M; Pedersen, T R; Gustavsson, B

    2009-02-13

    Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

  15. Pump-induced refractive index modulation and dispersions in Er3+-doped fibers

    DEFF Research Database (Denmark)

    Thirstrup, Carsten; Shi, Yuan

    1996-01-01

    A novel measurement system provides determination of pump induced phase shifts in erbium doped fibers with an accuracy of ~π/20. Using this system, a systematical analysis of the pump induced modulation of the refractive index and dispersions for a signal at 1550 nm and a pump at 980 nm is reported....... The analysis contains measurements of pump induced refractive index changes as function of wavelength, pump power, and doping concentration. A model taking account of the contribution to the refractive index changes from optical transitions between 4 I15/2 states and 4I13/2 states in Er3+ yields good agreement...

  16. Electronic Unit Pump Test Bench Development and Pump Properties Research

    Institute of Scientific and Technical Information of China (English)

    LIU Bo-lan; HUANG Ying; ZHANG Fu-jun; ZHAO Chang-lu

    2006-01-01

    A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection control method is given out and the control accuracy can be 0.1° crank degree. The bench can test bot h mechanical unit pump and electronic unit pump. A test model-PLD12 electronic unit pump is tested. Full pump delivery map and some influence factors test is d one. Experimental results show that the injection quantity is linear with the de livery angle. The quantity change rate is 15% when fuel temperature increases 30℃. The delivery quantity per cycle increases 30mg at 28V drive voltage. T he average delivery difference for two same type pumps is 5%. Test results show that the bench can be used for unit pump verification.

  17. Optical atomic magnetometer

    Science.gov (United States)

    Budker, Dmitry; Higbie, James; Corsini, Eric P

    2013-11-19

    An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

  18. Heat driven pulse pump

    Science.gov (United States)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  19. Enhanced efficiency of AlGaInP disk laser by in-well pumping.

    Science.gov (United States)

    Mateo, C M N; Brauch, U; Schwarzbäck, T; Kahle, H; Jetter, M; Abdou Ahmed, M; Michler, P; Graf, T

    2015-02-09

    The performance of a 665-nm GaInP disk laser operated continuous-wave at 15°C both in-well-pumped at 640 nm and barrier pumped at 532 nm is reported. The efficiency with respect to the absorbed power was enhanced by 3.5 times when using a 640-nm pump instead of a 532-nm pump. In-well pumping which is based on the absorption of the pump photons within the quantum-well heterostructures of the gain region instead of short-wavelength absorption in the barrier and spacer regions reduces the quantum defect between pump and laser photon and hence the heat generation. A slope efficiency of 60% with respect to the absorbed pump power was obtained by in-well pumping at 15°C. Continuous-wave laser operation was further demonstrated at heat sink temperatures of up to 55°C. Both the measurement of photoluminescence and COMSOL simulation show that the overall heat load in the in-well pumped laser is smaller than in the barrier-pumped laser. These results demonstrate the potential of optical in-well pumping for the operation of red AlGaInP disk lasers if combined with means for efficient pump-light absorption.

  20. Pulsed differential pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, G.N.; Bagautdinov, F.A.; Rybalov, S.V.

    1985-06-01

    A pulsed differential pumping system is described for extracting an electron beam from a shaping region at a pressure of 10/sup -5/ torr into a volume with a pressure of 10-100 torr. A fast valve is used with appropriate geometrical parameters to reduce the length of the outlet channel considerable while increasing its diameter. Test results are given. The pumping system has two sections which communicate one with the other and with the volume at the elevated pressure which is produced by gasdynamic nozzles.