WorldWideScience

Sample records for pumped ring cavity

  1. Spontaneous symmetry breaking in synchronously pumped fiber ring cavities

    CERN Document Server

    Schmidberger, Michael J; Biancalana, Fabio; Russell, Philip St J; Joly, Nicolas Y

    2013-01-01

    We introduce a new equation that describes the spatio-temporal evolution of arbitrary pulses propagating in a fiber-ring cavity. This model is a significant extension of the traditionally used Lugiato-Lefever model. We demonstrate spontaneous symmetry breaking as well as multistability regimes in a synchronously pumped fiber-ring cavity. The equation can be applied to virtually any type of waveguide-based ring cavity.

  2. Multiple four-wave mixing and Kerr combs in a bichromatically pumped nonlinear fiber ring cavity.

    Science.gov (United States)

    Ceoldo, D; Bendahmane, A; Fatome, J; Millot, G; Hansson, T; Modotto, D; Wabnitz, S; Kibler, B

    2016-12-01

    We report numerical and experimental studies of multiple four-wave mixing processes emerging from dual-frequency pumping of a passive nonlinear fiber ring cavity. We observe the formation of a periodic train of nearly background-free soliton pulses associated with Kerr frequency combs. The generation of resonant dispersive waves is also reported.

  3. GHz-bandwidth upconversion detector using a unidirectional ring cavity to reduce multilongitudinal mode pump effects

    DEFF Research Database (Denmark)

    Meng, Lichun; Høgstedt, Lasse; Tidemand-Lichtenberg, Peter

    2017-01-01

    narrow-linewidth lasers in a fiber coupler while tuning their wavelength difference down to 10 pm or less. The SFG crystal is placed inside an Nd:YVO4 ring cavity that provides 1064 nm circulating pump powers of up to 150 W in unidirectional operation. Measured Fabry-Perot spectrum at 1064 nm confirms...... for cooling, the GHz-bandwidth upconverter can readily be extended to the mid-IR (2 - 5 mu m) as an alternative to cooled low-bandgap semiconductor detectors for applications such as high-speed free-space optical communications. (C) 2017 Optical Society of America...

  4. Vibration insensitive optical ring cavity

    Institute of Scientific and Technical Information of China (English)

    Miao Jin; Jiang Yan-Yi; Fang Su; Bi Zhi-Yi; Ma Long-Sheng

    2009-01-01

    The mounting configuration of an optical ring cavity is optimized for vibration insensitivity by finite element analysis. A minimum response to vertical accelerations is found by simulations made for different supporting positions.

  5. Diode-pumped Alexandrite ring laser for lidar applications

    Science.gov (United States)

    Munk, A.; Jungbluth, B.; Strotkamp, M.; Hoffmann, H.-D.; Poprawe, R.; Höffner, J.

    2016-03-01

    We present design and performance data of a diode-pumped Q-switched Alexandrite ring laser in the millijoule regime, which is longitudinally pumped by laser diode bar modules in the red spectral range. As a first step, a linear resonator was designed and characterized in qcw operation as well as in Q-switched operation. Based on these investigations, two separate linear cavities were set up, each with one Alexandrite crystal longitudinally pumped by one diode module. The two cavities are fused together and form a ring cavity which yields up to 6 mJ pulse burst energy in the qcw regime at 770 nm.

  6. Combination ring cavity and backward Raman waveguide amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Kurnit, N.A.

    1981-03-13

    A combination regenerative ring and backward Raman waveguide amplifier and a combination regenerative ring oscillator and backward Raman waveguide amplifier which produce Raman amplification, pulse compression, and efficient energy extraction from the CO/sub 2/ laser pump signal for conversion into a Stokes radiation signal. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman waveguide amplifier. The backward Raman waveguide amplifier configuration extracts a major portion of the remaining energy from the CO/sub 2/ laser pump signal for conversion to Stokes radiation.

  7. 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.

  8. 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....

  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. All-solid-state ultraviolet laser based on frequency doubling in an external ring cavity

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An all-solid-state ultraviolet laser based on frequency doubling in an external ring cavity with low input pump power is reported. Both second harmonic generation (SHG) and fourth harmonic generation (FHG) occurred in an external threemirrors ring cavity. The need for impedance matching of this cavity to the input radiation was eliminated and the cavity adaptation was simplified, because the mirrors were not highly reflecting at 1064 nm and the cavity resonates only at 532 nm. Experiment results demonstrate that the conversion efficiency of this external cavity is higher than that of the singlepass condition.

  11. Bifurcation structure of an optical ring cavity

    DEFF Research Database (Denmark)

    Kubstrup, C.; Mosekilde, Erik

    1996-01-01

    One- and two-dimensional continuation techniques are applied to determine the basic bifurcation structure for an optical ring cavity with a nonlinear absorbing element (the Ikeda Map). By virtue of the periodic structure of the map, families of similar solutions develop in parameter space. Within...

  12. Synchronization of Bloch oscillations by a ring cavity.

    Science.gov (United States)

    Samoylova, M; Piovella, N; Robb, G R M; Bachelard, R; Courteille, Ph W

    2015-06-01

    We consider Bloch oscillations of ultracold atoms stored in a one-dimensional vertical optical lattice and simultaneously interacting with a unidirectionally pumped optical ring cavity whose vertical arm is collinear with the optical lattice. We find that the feedback provided by the cavity field on the atomic motion synchronizes Bloch oscillations via a mode-locking mechanism, steering the atoms to the lowest Bloch band. It also stabilizes Bloch oscillations against noise, and even suppresses dephasing due to atom-atom interactions. Furthermore, it generates periodic bursts of light emitted into the counter-propagating cavity mode, providing a non-destructive monitor of the atomic dynamics. All these features may be crucial for future improvements of the design of atomic gravimeters based on recording Bloch oscillations.

  13. Efficient frequency doubling at 776 nm in a ring cavity

    Science.gov (United States)

    Han, Zhen-Hai; Liu, Shi-Long; Liu, Shi-Kai; Ding, Dong-Sheng; Zhou, Zhi-Yuan

    2017-08-01

    We report efficient frequency doubling (FD) at 776 nm using periodically poled LiNbO3 (PPLN) in a ring cavity pumped by a commercial erbium-doped fiber amplifier (EDFA) operating at 1552 nm. Two sets of input couplers are used that have been optimized to operate in the low pump and high pump regimes. The maximum conversion efficiencies measured for these couplers are 65.8% (transmittance T=4.5%) and 65.9% (T=9.1%). The internal conversion efficiencies are 85.0% and 88.2%, respectively, after the mode-matching efficiency and filtering transmittance have been taken into account. The maximum output powers obtained for the two couplers are 333 mW and 602 mW at pump powers of 535 mW and 999 mW, respectively. Coupling efficiency of more than 80% to single mode fibers indicates the high beam quality of the FD laser. This FD laser will be useful for quantum optics experiments in the telecommunications band and atomic physics experiments.

  14. Fiber cavity ring down and gain amplification effect

    Science.gov (United States)

    Silva, Susana; Magalhães, Regina; Pérez-Herrera, Rosa Ana; Lopez-Amo, Manuel; Marques, M. B.; Frazão, O.

    2016-12-01

    The effect of an erbium-doped fiber amplifier (EDFA) placed inside the fiber ring of a cavity ring down (CRD) configuration is studied. The limitations and advantages of this configuration are discussed, and the study of the ring-down time as a function of the current applied and gain to the EDFA is also presented. In this case, the power fluctuations in the output signal are strongly dependent on the cavity ring-down time with the EDFA gain.

  15. Cavity Ring-Down Spectroscopy of Etching Plasmas

    Science.gov (United States)

    Booth, Jean-Paul; Cunge, Gilles; Biennier, Ludovic; Romanini, Daniele; Katachanov, Alexander

    1999-10-01

    Many of the reactive species of interest in etching plasmas absorb light in the UV spectral region (200 ~ 300 nm). Measurement of these weak absorbances (10-2 ~ 10-4 for a single pass) allows their absolute concentration to be determined. Previously, low-resolution spectra have been obtained using broad-band absorption spectroscopy, using a Xe arc lamp as the light source and a small monochromator equipped with a CCD Camera. Here we report high-resolution measurements using the recently developed Cavity Ring-Down Spectroscopy (CRDS) technique. The pulsed tunable output of an excimer pumped doubled dye laser was injected into a high-Q optical cavity in which the plasma is included. The absorbance as a function of wavelength is then deduced from the lifetime of the light pulse in the cavity. This technique offers the possibility of real-time (1 second) absolute concentration measurements. Results have been obtained for the detection of CF, CF_2, AlF and SiF2 radicals in capacitively-coupled radio-frequency plasmas in fluorocarbon gases. However, the deduction of absolute concentrations from CRDS spectra is complicated by the phenomenon of non-single exponential decays when the line-width of the laser is greater then that of the transition observed.

  16. Cavity Ring-down Spectroscopic System And Method

    KAUST Repository

    Alquaity, Awad Bin Saud

    2015-05-14

    A system and method for cavity ring-down spectroscopy can include a pulsed quantum cascade laser, an optical ring-down cavity, a photodetector, and an oscilloscope. The system and method can produce pulse widths of less than 200 ns with bandwidths greater than 300 pm, as well as provide temporal resolution of greater than 10 .mu.s.

  17. A Coupled Cavity Micro Fluidic Dye Ring Laser

    CERN Document Server

    Gersborg-Hansen, M; Mortensen, N A; Kristensen, A

    2004-01-01

    We present a laterally emitting, coupled cavity micro fluidic dye ring laser, suitable for integration into lab-on-a-chip micro systems. The micro-fluidic laser has been successfully designed, fabricated, characterized and modelled. The resonator is formed by a micro-fluidic channel bounded by two isosceles triangle mirrors. The micro-fluidic laser structure is defined using photo lithography in 10 microns thick SU-8 polymer on a glass substrate. The micro fluidic channel is sealed by a glass lid, using PMMA adhesive bonding. The laser is characterized using the laser dye Rhodamine 6G dissolved in ethanol or ethylene glycol as the active gain medium, which is pumped through the micro-fluidic channel and laser resonator. The dye laser is optically pumped normal to the chip plane at 532 nm by a pulsed, frequency doubled Nd:YAG laser and lasing is observed with a threshold pump pulse energy flux of around 55 micro-Joule/square-milimeter. The lasing is multi-mode, and the laser has switchable output coupling into...

  18. Saturn's Rings and Associated Ring Plasma Cavity: Evidence for Slow Ring Erosion

    Science.gov (United States)

    Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Persoon, A. M.; MacDowall, R. J.

    2017-01-01

    We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 Rs (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak impact-created plasma outflows over the densest portion of the rings (central B-ring). In sharp contrast, the Cassini Radio and Plasma Wave System (RPWS) observations identify the presence of a ring-plasma cavity located in the central portion of the B-ring, with little evidence of impact-related plasma. While previous Voyager era studies have predicted unstable ion orbits over the C- ring, leading to field-aligned plasma transport to Saturns ionosphere, the Cassini RPWS observations do not reveal evidence for such instability-created plasma fountains. Given the passive ring loss processes observed by Cassini, we find that the ring lifetimes should extend >10(exp 9) years, and that there is limited evidence for prompt destruction (loss in <100 Myrs).

  19. 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

  20. Selection of lasing direction in single mode semiconductor square ring cavities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin-Woong; Kim, Kyoung-Youm; Moon, Hee-Jong; Hyun, Kyung-Sook, E-mail: kshyun@sejong.ac.kr [Department of Optical Engineering, Sejong University, 98 Kunja-Dong, Kwangjin-K, Seoul 143-747 (Korea, Republic of)

    2016-02-07

    We propose and demonstrate a selection scheme of lasing direction by imposing a loss imbalance structure into the single mode square ring cavity. The control of the traveling direction is realized by introducing a taper-step section in one of the straight waveguides of the square ring cavity. It was shown by semi-analytic calculation that the taper-step section in the cavity provides effective loss imbalance between two travelling directions as the round trip repeats. Various kinds of square cavities were fabricated using InGaAsP/InGaAs multiple quantum well semiconductor materials in order to test the direction selectivity while maintaining the single mode. We also measured the pump power dependent lasing spectra to investigate the maintenance property of the lasing direction. The experimental results demonstrated that the proposed scheme is an efficient means for a unidirectional lasing in a single mode laser.

  1. Hollow Rotor Progressing Cavity Pump Technique for Oil Production

    Institute of Scientific and Technical Information of China (English)

    Cao Gang

    2002-01-01

    @@ Features of Hollow RotorProgressing Cavity Pump(HRPCP) (1) Keep the path forPCP well-flushing.Clean over the producing wells quickly without shutting off the wells. Heat loss is low while the efficiency is high.

  2. Transverse modes of a diode-laser pumped monolithic unidirectional non-planar ring laser

    Institute of Scientific and Technical Information of China (English)

    Keying Wu(吴克瑛); Suhui Yang(杨苏辉); Guanghui Wei(魏光辉)

    2003-01-01

    Diode-laser pumped monolithic single-frequency non-planar ring laser has the advantages of compactness,reliability and high efficiency. But when the pump power is high enough, the thermal effect will be seriousand the high-order transverse modes will appear. Therefore the single-mode output power is limited. Inthis paper, the mechanism of generating the high-order transverse modes in the monolithic unidirectionalnon-planar ring cavity is analyzed using ray tracing method. The calculated results are in agreement withthe experiments.

  3. Optomechanical damping of a nanomembrane inside an optical ring cavity

    CERN Document Server

    Yilmaz, Arzu; Wolf, Philip; Schmidt, Dag; Eisele, Max; Zimmermann, Claus; Slama, Sebastian

    2016-01-01

    We experimentally and theoretically investigate mechanical nanooscillators coupled to the light in an optical ring resonator made of dielectric mirrors. We identify an optomechanical damping mechanism that is fundamentally different to the well known cooling in standing wave cavities. While, in a standing wave cavity the mechanical oscillation shifts the resonance frequency of the cavity in a ring resonator the frequency does not change. Instead the position of the nodes is shifted with the mechanical excursion. We derive the damping rates and test the results experimentally with a silicon-nitride nanomembrane. It turns out that scattering from small imperfections of the dielectric mirror coatings has to be taken into account to explain the value of the measured damping rate. We extend our theoretical model and regard a second reflector in the cavity that captures the effects of mirror back scattering. This model can be used to also describe the situation of two membranes that both interact with the cavity fi...

  4. Investigation on the effect of EDFA location in ring cavity Brillouin-Erbium fiber laser.

    Science.gov (United States)

    Hambali, Nor Azura Malini A; Mahdi, Mohd Adzir; Al-Mansoori, Mohammed Hayder; Abas, Ahmad Fauzi; Saripan, M Iqbal

    2009-07-06

    We have investigated the characteristics of Brillouin-Erbium fiber laser (BEFL) with variation of Erbium-doped fiber amplifier (EDFA) locations in a ring cavity configuration. Three possible locations of the EDFA in the laser cavity have been studied. The experimental results show that the location of EDFA plays vital role in determining the output power and the tuning range. Besides the Erbium gain, Brillouin gain also contributes to the performance of the BEFL. By placing the EDFA next to the Brillouin gain medium (dispersion compensating fiber), the Brillouin pump signal is amplified thereby generating higher intensities of Brillouin Stokes line. This efficient process suppresses the free running self-lasing cavity modes from oscillating in cavity as a result of higher Stokes laser power and thus provide a wider tuning range. At the injected Brillouin pump power of 1.6 mW and the maximum 1480 nm pump power of 135 mW, the maximum Stokes laser power of 25.1 mW was measured and a tuning range of 50 nm without any self-lasing cavity modes was obtained.

  5. Pulsed cavity ring-down spectroscopy in combustion environments

    NARCIS (Netherlands)

    Evertsen, Rogier

    2002-01-01

    This thesis gives an introduction to pulsed cavity ring-down absorption spectroscopy (CRDS) and its application in combustion research. Experimental results have been compared to numerical simulations, providing a means to validate reaction mechanisms and numerical approaches. Up to now, the

  6. Cavity ring down spectroscopy with a free-electron laser

    NARCIS (Netherlands)

    Engeln, R.; van den Berg, E.; Meijer, G.; Lin, L.; Knippels, G.M.H.; van der Meer, A. F. G.

    1997-01-01

    A cavity ring down (CRD) absorption experiment is performed with a free-electron laser (FEL) operating in the 10-11 mu m region. A short infrared pulse of approximately 20 ns, sliced from the much longer FEL pulse, is used to measure CRD spectra of ethylene in two different ways. First, ''

  7. Stabilizing and controlling domain walls and dark-ring cavity solitons.

    Science.gov (United States)

    Pérez-Arjona, Isabel; Silva, Fernando; Roldán, Eugenio; de Valcárcel, Germán

    2004-05-17

    We demonstrate two alternative techniques for controlling and stabilizing domain walls (DW) in phase-sensitive, nonlinear optical resonators. The first of them uses input pumps with spatially modulated phase and can be applied also to dark-ring cavity solitons. An optical memory based on the latter is demonstrated. Here the physical mechanism of control relies on the advection caused to any feature by the phase gradients. The second technique uses a plane wave input pump with holes of null intensity across its transverse plane, which are able to capture DWs. Here the physical mechanism of control is of topological nature. When distributed as a regular array, these holes delimit spatial optical bits which constitute an optical memory. These techniques are illustrated in a degenerate optical parametric oscillator model, but can be applied to any phase-sensitive nonlinear optical cavity.

  8. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    Science.gov (United States)

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

  9. Point Lepreau primary heat transport pump wear ring cracking

    Energy Technology Data Exchange (ETDEWEB)

    Licina, G. [Structural Integrity Associates, Inc., San Jose, California (United States); Rankin, B. [Point Lepreau Nuclear Generating Station, Fredericton, New Brunswick (Canada)

    2011-07-01

    The number 3 Primary Heat Transport (PHT) pump from Point Lepreau Nuclear Generating Station (Point Lepreau) was disassembled after more than 30 years of service for inspection during station refurbishment. The disassembly and inspection were performed to provide assurance of continued satisfactory operation during life extension. The inspection revealed cracks in the wear ring, at and near the tack welds (Type 309 stainless steel weld metal) at the cap screws that attach the Type 420 stainless steel wear ring to the body of the pump. Investigative work consisted of on-site PT and replication of the microstructure at the surface of the wear ring, subsequent impressions of two crack faces, and hardness determinations. This paper describes the investigative work and conclusions associated with resolution of the following questions: 1. What is the most likely cause of the cracking? 2. Will the cracks propagate within the base metal of the wear ring? 3. If propagation is possible, what is the risk of cracks intersecting, such that a piece of metal could become dislodged? Question number 3 has clear ramifications with respect to foreign material entering and damaging a nuclear fuel-containing pressure tube. There are also questions associated with extent of condition, specifically, whether other PHT pumps may have similar or worse cracking and whether such cracks will grow. Results will be applied to wear rings in other PHT pumps at Point Lepreau and are likely to be applicable to similar components in other CANDU PHT pumps. (author)

  10. Infrared Spectroscopy with a Cavity Ring-Down Spectrometer

    Science.gov (United States)

    2014-08-01

    Fourier transform infrared spectroscopy ( FTIR ) measures the transmission of the excitation source and then calculates the absorption from that measured...laser FTIR Fourier transform infrared spectroscopy HgCdTe mercury, cadmium, tellurium I absorbed light intensity I0 initial light intensity l...Infrared Spectroscopy with a Cavity Ring-Down Spectrometer by Logan S Marcus, Ellen L Holthoff, and Paul M Pellegrino ARL-TR-7031 August

  11. Silicon reflectors for external cavity lasers based on ring resonators

    Science.gov (United States)

    Wang, Chao; Li, Xia; Jin, Hao; Yu, Hui; Yang, Jianyi; Jiang, Xiaoqing

    2017-01-01

    We propose and experimentally investigate types of silicon ring reflectors on Silicon-On-Insulator (SOI) platform. These reflectors are used for realizing the silicon hybrid external cavity lasers. A suspended edge coupler is used to connect the reflective semiconductor optical amplifier (RSOA) chip and the reflectors. The properties of the reflectors and the hybrid external cavity lasers with these reflectors are illustrated. The experimental results show that all of those reflectors have a high reflectivity and the highest reflectivity can up to be 95%. The lowest insertion loss can be as low as 0.4 dB. The output power of the hybrid external cavity lasers with these reflectors can reach mW magnitude and the highest output power is 6.1 mW. Over 30 dB side mode suppression ratio is obtained.

  12. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    Energy Technology Data Exchange (ETDEWEB)

    Christopher C. Carter

    2002-12-31

    SRD tested a number of different length cavities during this past quarter. Continuous transmission was observed with cavity lengths from 65 to 12 cm. The 65 cm cavity was replaced with a 39 cm cavity for work performed during this quarter. Flue gas components were tested for background absorptions and any interference with the determination of accurate mercury concentrations. Sulfur dioxide was found to absorb fairly strongly in the region of the mercury transition, but the Cavity Ring-Down (CRD) instrument was still able to detect mercury at subparts-per-billion by volume (ppb) levels. Additional flue gases tested included H{sub 2}O, CO, CO{sub 2}, NO, NO{sub 2}. None of these flue gas constituents showed any observable absorption in the ultraviolet region near the atomic mercury transition. Work was also initiated in speciation studies. In particular mercury chloride (HgCl{sub 2}) was tested. A mercury signal was detected from a gas stream containing HgCl{sub 2}. SRD was not able to determine definitively if there exists a spectral shift great enough to separate HgCl{sub 2} from elemental mercury in these initial tests.

  13. Note: Broadband cavity ring-down spectroscopy of an intra-cavity bulk sample.

    Science.gov (United States)

    Zeuner, T; Paa, W; Mühlig, C; Stafast, H

    2013-03-01

    A cavity ring-down (CRD) setup equipped with a pulsed broadband light source (480 nm ≤ λ ≤ 650 nm) and a multichannel detection system (temporal gate width Δτ = 20 ns) is used to simultaneously record the optical loss spectrum of an intra-cavity CaF2 sample and its changes upon transverse ArF laser irradiation at 193 nm. The CRD setup with mirrors of high reflectivity (R > 99.93%) allows to register loss changes of 5 × 10(-5) with a spectral resolution of 0.3 nm in less than 2 min.

  14. Entanglement of fields in coupled cavities: Effects of pumping and fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, S., E-mail: siva@igcar.gov.i [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2010-04-05

    A system of two coupled cavities is studied in the context of bipartite, continuous variable entanglement. One of the cavities is pumped by an external classical source that is coupled quadratically, to the cavity field. Dynamics of entanglement, quantified by covariance measure [V.V. Dodonov, et al., Phys. Lett. A 296 (2002) 73], in the presence of cavity-cavity coupling and external pumping is investigated. The importance of tailoring the coupling between the cavities is brought out by studying the effects of pump fluctuations on the entanglement.

  15. Dynamic properties of a pulse-pumped fiber laser with a short, high-gain cavity

    Science.gov (United States)

    Yang, Chaolin; Guo, Junhong; Wei, Pu; Wan, Hongdan; Xu, Ji; Wang, Jin

    2016-09-01

    We demonstrate a pulsed high-gain all-fiber laser without intracavity modulators, where a short and heavily Erbium-doped fiber is used as the gain medium in a ring cavity. By pulsed-pumping this short high gain cavity and tuning an intracavity variable optical coupler, the laser generates optical pulses with a pulse-width of μs at a repetition rate in the order of kHz down to one-shot operation. Furthermore, dynamic properties of this laser are investigated theoretically based on a traveling-wave-model, in which an adaptive-discrete-grid-finite-difference-method is applied. The simulation results validate the experimental results. The demonstrated pulsed laser is compact, flexible and cost-effective, which will have great potential for applications in all-optical sensing and communication systems.

  16. Solid-state led-pumped YAG:Nd/sup 3 +/ ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Belozerov, S.A.; Korniyenko, L.S.; Kravtsov, N.V.; Kuratev, I.I.; Rusakov, S.I.; Stel' makh, M.F.; Shelayev, A.A.; Shelayev, A.N.

    1984-01-12

    The article is a report on attainment of stimulated emission in a YAG:Nd/sup 3 +/ solid-state ring laser (lambda = 1.06 ..mu..m) with both cw and pulsed pumping by light-emitting diodes. The YAG:Nd/sup 3 +/ crystal was 1.5 mm in diameter and 20 mm long with Brewster faces. The laser was made as a monoblock in which channels were drilled for the laser beam. Total losses on the mirrors did not exceed 0.2%. Cavity perimeter was 22 cm. Pumping was by two lines of LEDs based on epitaxial heterostructure Al/sub x/Ga/sub 1-x/As. In the pulsed pumping mode maximum pulse duration was 8 ms, and maximum recurrence rate was 100 Hz. The threshold pumping current in the pulsed mode was about 1.1 A with prf of 10 Hz, pulse duration of 0.5 ms and temperature of 300 K. Maximum admissible current in this mode is 6 A. In cw pumping, the LED lines were fed by a stabilized DC source at voltage of about 40 V. Threshold pumping current was about 1.5 A, i.e., the threshold power was about 60 W. The optimum maximum current in the cw mode was about 2.0 A. Emission power was a near-linear function of current through the LEDs in either pumping mode. It was experimentally demonstrated that a rotating ring laser can produce stable beats with both cw and pulsed LED pumping. It should be possible to use self-switching modes to measure non-reciprocal effects. 5 references, 2 figures.

  17. All metal progressing cavity pumps deployed in SAGD

    Energy Technology Data Exchange (ETDEWEB)

    Rae, M. [Shell Canada (Canada); Seince, L. [PCM Canada (Canada); Mitskopoulos, M. [Kudu industries (Canada)

    2011-07-01

    In Canada, 80% of oilsands reserves require in situ recovery and SAGD is to date the most used method. World-wide, SAGD and other enhanced recovery methods have been employed using the all metal progressive cavity pump (AMPCP) for 4 years now. Test results and the learning curve associated with use of this pump have been documented. This paper gives an overview of one run of an AMPCP in a SAGD application. This run was conducted in a producing well in Shell's Orion field in Cold Lake (AB) over a 14 month period. Results showed that the AMPCP can handle a wide range of temperatures, adjust its speed to fit production when downhole conditions change and that its run life was better than expected. This paper demonstrated the versatility and robustness of the AMPCP and showed that the combination of steam and chemical stimulation can optimize production.

  18. Optimization of output coupling ratio on the performance of a ring-cavity Brillouin-erbium fiber laser.

    Science.gov (United States)

    Hambali, Nor Azura Malini A; Mahdi, Mohd Adzir; Al-Mansoori, Mohammed Hayder; Saripan, M Iqbal; Abas, Ahmad Fauzi

    2009-09-20

    The operation of a single-wavelength Brillouin-erbium fiber laser (BEFL) system with a Brillouin pump preamplified technique for different output coupling ratios in a ring cavity is experimentally demonstrated. The characteristics of Brillouin Stokes power and tunability were investigated in this research. The efficiency of the BEFL operation was obtained at an optimum output coupling ratio of 95%. By fixing the Brillouin pump wavelength at 1550 nm while its power was set at 1.6 mW and the 1480 pump power was set to its maximum value of 135 mW, the Brillioun Stokes power was found to be 28.7 mW. The Stokes signal can be tuned within a range of 60 nm from 1520 to 1580 nm without appearances of the self-lasing cavity modes in the laser system.

  19. [Fast and accurate extraction of ring-down time in cavity ring-down spectroscopy].

    Science.gov (United States)

    Wang, Dan; Hu, Ren-Zhi; Xie, Pin-Hua; Qin, Min; Ling, Liu-Yi; Duan, Jun

    2014-10-01

    Research is conducted to accurate and efficient algorithms for extracting ring-down time (r) in cavity ring-down spectroscopy (CRDS) which is used to measure NO3 radical in the atmosphere. Fast and accurate extraction of ring-down time guarantees more precise and higher speed of measurement. In this research, five kinds of commonly used algorithms are selected to extract ring-down time which respectively are fast Fourier transform (FFT) algorithm, discrete Fourier transform (DFT) algorithm, linear regression of the sum (LRS) algorithm, Levenberg-Marquardt (LM) algorithm and least squares (LS) algorithm. Simulated ring-down signals with various amplitude levels of white noises are fitted by using five kinds of the above-mentioned algorithms, and comparison and analysis is conducted to the fitting results of five kinds of algorithms from four respects: the vulnerability to noises, the accuracy and precision of the fitting, the speed of the fitting and preferable fitting ring-down signal waveform length The research results show that Levenberg-Marquardt algorithm and linear regression of the sum algorithm are able to provide more precise results and prove to have higher noises immunity, and by comparison, the fitting speed of Leven- berg-Marquardt algorithm turns out to be slower. In addition, by analysis of simulated ring-down signals, five to ten times of ring-down time is selected to be the best fitting waveform length because in this case, standard deviation of fitting results of five kinds of algorithms proves to be the minimum. External modulation diode laser and cavity which consists of two high reflectivity mirrors are used to construct a cavity ring-down spectroscopy detection system. According to our experimental conditions, in which the noise level is 0.2%, linear regression of the sum algorithm and Levenberg-Marquardt algorithm are selected to process experimental data. The experimental results show that the accuracy and precision of linear regression of

  20. Dependence of mis-alignment sensitivity of ring laser gyro cavity on cavity parameters

    Energy Technology Data Exchange (ETDEWEB)

    Sun Feng; Zhang Xi; Zhang Hongbo; Yang Changcheng, E-mail: sunok1234@sohu.com [Huazhong Institute of Electro-Optics - Wuhan National Lab for Optoelectronics, Wuhan, Hubei (China)

    2011-02-01

    The ring laser gyroscope (RLG), as a rotation sensor, has been widely used for navigation and guidance on vehicles and missiles. The environment of strong random-vibration and large acceleration may deteriorate the performance of the RLG due to the vibration-induced tilting of the mirrors. In this paper the RLG performance is theoretically analyzed and the parameters such as the beam diameter at the aperture, cavity mirror alignment sensitivities and power loss due to the mirror tilting are calculated. It is concluded that by carefully choosing the parameters, the significant loss in laser power can be avoided.

  1. Measurements of carbon-14 with cavity ring-down spectroscopy

    Science.gov (United States)

    McCartt, A. D.; Ognibene, T.; Bench, G.; Turteltaub, K.

    2015-10-01

    Accelerator Mass Spectrometry (AMS) is the most sensitive method for quantitation of 14C in biological samples. This technology has been used in a variety of low dose, human health related studies over the last 20 years when very high sensitivity was needed. AMS helped pioneer these scientific methods, but its expensive facilities and requirements for highly trained technical staff have limited their proliferation. Quantification of 14C by cavity ring-down spectroscopy (CRDS) offers an approach that eliminates many of the shortcomings of an accelerator-based system and would supplement the use of AMS in biomedical research. Our initial prototype, using a non-ideal wavelength laser and under suboptimal experimental conditions, has a 3.5-modern, 1- σ precision for detection of milligram-sized, carbon-14-elevated samples. These results demonstrate proof of principle and provided a starting point for the development of a spectrometer capable of biologically relevant sensitivities.

  2. Doppler broadening thermometry based on cavity ring-down spectroscopy

    CERN Document Server

    Cheng, C -F; Sun, Y R; Tan, Y; Kang, P; Hu, S -M

    2015-01-01

    A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which also reduces the influence due to collisions. By recording the spectrum of C$_2$H$_2$ at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. The influence on the spectroscopy-determined temperatures has been investigated, including the "hidden" weak lines overlapped with the selected transition for DBT measurements. The reproducibility has also been examined to be better than 10 ppm, and it indicates that the instrument is feasible for DBT measurement toward a precision at the ppm level.

  3. Use of laser diodes in cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zare, R.N.; Paldus, B.A.; Ma, Y.; Xie, J. [Stanford Univ., CA (United States)

    1997-12-31

    We have demonstrated that cavity ring-down spectroscopy (CRDS), a highly sensitive absorption technique, is versatile enough to serve as a complete diagnostic for materials process control. In particular, we have used CRDS in the ultraviolet to determine the concentration profile of methyl radicals in a hot-filament diamond reactor; we have applied CRDS in the mid-infrared to detect 50 ppb of methane in a N{sub 2} environment; and, we have extended CRDS so that we can use continuous-wave diode laser sources. Using a laser diode at 810 nm, we were able to achieve a sensitivity of 2 x 10{sup -8} cm{sup -1}. Thus, CRDS can be used not only as an in situ diagnostic for investigating the chemistry of diamond film deposition, but it can also be used as a gas purity diagnostic for any chemical vapor deposition system.

  4. Miniaturized cavity ring-down detection in a liquid flow cell

    NARCIS (Netherlands)

    Bahnev, B.; Sneppen, van der L.; Wiskerke, A.E.; Ariese, F.; Gooijer, C.; Ubachs, W.M.G.

    2005-01-01

    A novel method for applying cavity ring-down spectroscopy in the liquid phase, compatible with LC analyses, is presented. The core of the setup is a home-built cavity ring-down flow cell (cell volume 12 muL) that is constructed using a silicon rubber spacer, which is clamped leak-tight between two

  5. Ultra low-energy switch based on a cavity soliton laser with pump modulation

    Science.gov (United States)

    Eslami, M.; Gandomani, S. Z.; Prati, F.; Tajalli, H.; Kheradmand, R.

    2017-01-01

    We study the effects of pump modulation in a cavity soliton laser consisting of a vertical cavity surface emitting laser with an intra-cavity saturable absorber. We show that a drifting soliton experiences enhanced mobility features by modulating the pump at the resonance frequency, and the effects are even larger below resonance. In particular, pump modulation reduces the rest time of the soliton in the initial stage of the motion and it increases its drift velocity in this regime. Moreover, pump modulation allows a decrease in the switching energy of the soliton to an amount equal to 36 photons. These results indicate that pump modulation is a promising way for the use of a cavity soliton laser as a fast optical buffer and an ultra low-energy optical switch.

  6. Medical Diagnostic Breath Analysis by Cavity Ring Down Spectroscopy

    Science.gov (United States)

    Guss, Joseph S.; Metsälä, Markus; Halonen, Lauri

    2009-06-01

    Certain medical conditions give rise to the presence of chemicals in the bloodstream. These chemicals - known as biomarkers - may also be present in low concentrations in human breath. Cavity ring down spectroscopy possesses the requisite selectivity and sensitivity to detect such biomarkers in the congested spectrum of a breath sample. The ulcer-causing bacterium, Helicobacter pylori, is a prolific producer of the enzyme urease, which catalyses the breakdown of urea ((NH_2)_2CO) in the stomach as follows: (NH_2)_2CO + H_2O ⟶ CO_2 + 2NH_3 Currently, breath tests seeking altered carbon-isotope ratios in exhaled CO_2 after the ingestion of ^{13}C- or ^{14}C-labeled urea are used to diagnose H. pylori infection. We present recent results from an ongoing collaboration with Tampere Area University Hospital. The study involves 100 patients (both infected and uninfected) and concerns the possible correlation between the bacterial infection and breath ammonia. D. Y. Graham, P. D. Klein, D. J. Evans, Jr, D. G. Evans, L. C. Alpert, A. R. Opekun, T. W. Boutton, Lancet 1(8543), 1174-7 March 1987.

  7. S-Nitrosothiols Observed Using Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Rad, Mary Lynn; Gaston, Benjamin M.; Lehmann, Kevin

    2017-06-01

    The biological importance of nitric oxide has been known for nearly forty years due to its role in cardiovascular and nervous signaling. The main carrier molecules, s-nitrosothiols (RSNOs), are of additional interest due to their role in signaling reactions. Additionally, these compounds are related to several diseases including muscular dystrophy, stroke, myocardial infarction, Alzheimer's disease, Parkinson's disease, cystic fibrosis, asthma, and pulmonary arterial hypertension. One of the main barriers to elucidating the role of these RSNOs is the low (nanomolar) concentration present in samples of low volume (typically ˜100 μL). To this end we have set up a cavity ring-down spectrometer tuned to observe ^{14}NO and ^{15}NO released from cell growth samples. To decrease the limit of detection we have implemented a laser locking scheme employing Zeeman modulation of NO in a reference cell and have tuned the polarization of the laser using a half wave plate to optimize the polarization for the inherent birefringence of the CRDS mirrors. Progress toward measuring RSNO concentration in biological samples will be presented.

  8. Control of ring lasers by means of coupled cavities

    DEFF Research Database (Denmark)

    Buchhave, Preben; Abitan, Haim; Tidemand-Lichtenberg, Peter

    2000-01-01

    Variable phase coupling to an external ring is used to control a unidirectional ring laser. The observed behavior of the coupled rings is explained theoretically. We have found experimentally that by quickly changing the phase of the feedback from the external ring it is possible to Q-switch the ...

  9. High power dual-wavelength tunable fiber laser in linear and ring cavity configurations

    Institute of Scientific and Technical Information of China (English)

    H. Ahmad; A. A. Latif; M. Z. Zulkifli; N. A. Awang; S. W. Harun

    2012-01-01

    We describe and compare the performances of two crucial configurations for a tunable dual-wavelength fiber laser,namely,the linear and ring configurations.The performances of these two cavities and the tunability in the dual-wavelength output varied from 0.8 to 11.9 nm are characterized.The ring cavity provides a better performance,achieving an average output power of 0.5 dBm,with a power fluctuation of only 1.1 dB and a signal-to-noise ratio (SNR) of 66 dB.Moreover,the ring cavity has minimal or no background amplified spontaneous emission (ASE).

  10. Efficient second harmonic generation of a diode-laser-pumped CW Nd:YAG laser using monolithic MgO:LiNbO3 external resonant cavities

    Science.gov (United States)

    Kozlovsky, William J.; Nabors, C. D.; Byer, Robert L.

    1988-01-01

    56-percent efficient external-cavity-resonant second-harmonic generation of a diode-laser pumped, CW single-axial-mode Nd:YAG laser is reported. A theory of external doubling with a resonant fundamental is presented and compared to experimental results for three monolithic cavities of nonlinear MgO:LiNbO3. The best conversion efficiency was obtained with a 12.5-mm-long monolithic ring cavity doubler, which produced 29.7 mW of CW, single-axial model 532-nm radiation from an input of 52.5 mW.

  11. Discovery of higher order modes in a cylindrical reentrant-ring cavity resonator

    CERN Document Server

    Fan, Y; Carvalho, N C; Floch, J-M Le; Shan, Q; Tobar, M E

    2013-01-01

    Rigorous analysis of the properties of resonant modes in a reentrant cavity structure comprising of a post and ring is undertaken and verified experimentally. In particular for the first time we show the existence of higher order reentrant cavity modes in such a structure. Results show this cavity has a better displacement sensitivity compared to the common fundamental mode in a reentrant cylindrical cavity with just a single post. Thus, this type of cavity has the potential to operate as a highly sensitive transducer for a variety of precision measurement applications.

  12. Continuous-wave supercontinuum laser based on an erbium-doped fiber ring cavity incorporating a highly nonlinear optical fiber

    Science.gov (United States)

    Lee, Ju Han; Takushima, Yuichi; Kikuchi, Kazuro

    2005-10-01

    We experimentally demonstrate a novel erbium-doped fiber based continuous-wave (cw) supercontinuum laser. The laser has a simple ring-cavity structure incorporating an erbium-doped fiber and a highly nonlinear dispersion-shifted fiber (HNL-DSF). Differently from previously demonstrated cw supercontinuum sources based on single propagation of a strong Raman pump laser beam through a highly nonlinear fiber, erbium gain inside the cavity generates a seed light oscillation, and the oscillated light subsequently evolves into a supercontinuum by nonlinear effects such as modulation instability and stimulated Raman scattering in the HNL-DSF. High quality of the depolarized supercontinuum laser output with a spectral bandwidth larger than 250 nm is readily achieved.

  13. Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Terabayashi, Ryohei, E-mail: terabayashi.ryouhei@h.mbox.nagoya-u.ac.jp; Sonnenschein, Volker, E-mail: volker@nagoya-u.jp; Tomita, Hideki, E-mail: tomita@nagoya-u.jp; Hayashi, Noriyoshi, E-mail: hayashi.noriyoshi@h.mbox.nagoya-u.ac.jp; Kato, Shusuke, E-mail: katou.shuusuke@f.mbox.nagoya-u.ac.jp; Jin, Lei, E-mail: kin@nuee.nagoya-u.ac.jp; Yamanaka, Masahito, E-mail: yamanaka@nuee.nagoya-u.ac.jp; Nishizawa, Norihiko, E-mail: nishizawa@nuee.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan); Sato, Atsushi, E-mail: atsushi.sato@sekisui.com; Nozawa, Kohei, E-mail: kohei.nozawa@sekisui.com; Hashizume, Kenta, E-mail: kenta.hashizume@sekisui.com; Oh-hara, Toshinari, E-mail: toshinari.ohara@sekisui.com [Sekisui Medical Co., Ltd., Drug Development Solutions Center (Japan); Iguchi, Tetsuo, E-mail: t-iguchi@nucl.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan)

    2017-11-15

    A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

  14. Revised NASA axially symmetric ring model for coupled-cavity traveling-wave tubes

    Science.gov (United States)

    Wilson, Jeffrey D.

    1987-01-01

    A versatile large-signal, two-dimensional computer program is used by NASA to model coupled-cavity travelling-wave tubes (TWTs). In this model, the electron beam is divided into a series of disks, each of which is further divided into axially symmetric rings which can expand and contract. The trajectories of the electron rings and the radiofrequency (RF) fields are determined from the calculated axial and radial space-charge, RF, and magnetic forces as the rings pass through a sequence of cavities. By varying electrical and geometric properties of individual cavities, the model is capable of simulating severs, velocity tapers, and voltage jumps. The calculated electron ring trajectories can be used in designing magnetic focusing and multidepressed collectors. The details of using the program are presented, and results are compared with experimental data.

  15. Collective strong coupling of cold potassium atoms in a ring cavity

    CERN Document Server

    Culver, Robert; Megyeri, Balázs; Pahwa, Komal; Mudarikwa, Lawrence; Holynski, Michael; Courteille, Philippe W; Goldwin, Jon

    2016-01-01

    We present experiments on ensemble cavity quantum electrodynamics with cold potassium atoms in a high-finesse ring cavity. Potassium-39 atoms are cooled in a two-dimensional magneto-optical trap, and transferred to a three-dimensional trap which intersects the cavity mode. The apparatus is described in detail and the first observations of strong coupling with potassium atoms are presented. Collective strong coupling of atoms and light is demonstrated via the splitting of the cavity transmission spectrum and the avoided crossing of the normal modes.

  16. Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy.

    Science.gov (United States)

    Roberts, Hannah M; Shiller, Alan M

    2015-01-26

    Methane (CH4) is the third most abundant greenhouse gas (GHG) but is vastly understudied in comparison to carbon dioxide. Sources and sinks to the atmosphere vary considerably in estimation, including sources such as fresh and marine water systems. A new method to determine dissolved methane concentrations in discrete water samples has been evaluated. By analyzing an equilibrated headspace using laser cavity ring-down spectroscopy (CRDS), low nanomolar dissolved methane concentrations can be determined with high reproducibility (i.e., 0.13 nM detection limit and typical 4% RSD). While CRDS instruments cost roughly twice that of gas chromatographs (GC) usually used for methane determination, the process presented herein is substantially simpler, faster, and requires fewer materials than GC methods. Typically, 70-mL water samples are equilibrated with an equivalent amount of zero air in plastic syringes. The equilibrated headspace is transferred to a clean, dry syringe and then drawn into a Picarro G2301 CRDS analyzer via the instrument's pump. We demonstrate that this instrument holds a linear calibration into the sub-ppmv methane concentration range and holds a stable calibration for at least two years. Application of the method to shipboard dissolved methane determination in the northern Gulf of Mexico as well as river water is shown. Concentrations spanning nearly six orders of magnitude have been determined with this method.

  17. Temporal laser pulse manipulation using multiple optical ring-cavities

    Science.gov (United States)

    Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

    2010-01-01

    An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

  18. Continuous-wave Raman laser pumped within a semiconductor disk laser cavity.

    Science.gov (United States)

    Parrotta, Daniele C; Lubeigt, Walter; Kemp, Alan J; Burns, David; Dawson, Martin D; Hastie, Jennifer E

    2011-04-01

    A KGd(WO₄)₂ Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5.6 W of absorbed diode pump power, and output power up to 0.8 W at 1143 nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157 nm.

  19. Fiber Ring Laser In-cavity Phase Modulation

    Institute of Scientific and Technical Information of China (English)

    YU Benli; QIAN Jingren; LUO Jiatong; YANG Yinghai

    2001-01-01

    In this paper, experimental results of the in-cavity phase modulation induced by dithering PZT is reported. The dithering PZT can produce strong phase modulation, reshaping the laser output spectrum, but does not affect the laser linewidth, which is measured by homodyne method.

  20. Femtosecond laser direct writing of single mode polymer micro ring laser with high stability and low pumping threshold.

    Science.gov (United States)

    Parsanasab, Gholam-Mohammad; Moshkani, Mojtaba; Gharavi, Alireza

    2015-04-01

    We have demonstrated an optically pumped polymer microring laser fabricated by two photon polymerization (TPP) of SU-8. The gain medium is an organic dye (Rhodamine B) doped in SU-8, and the laser cavity is a double coupled microring structure. Single mode lasing was obtained from the two coupled rings each with 30 µm and 29 µm radii using Vernier effect. Low laser threshold of 0.4 µJ/mm(2) is achieved using 1 µm wide polymer waveguides and the quality factor is greater than 10(4) at 612.4 nm wavelength. The lasing remained stable with pump energies from threshold to energies as high as 125 times the threshold.

  1. Continuous Pump Assisted Conditional Synthesis of Nonclassical States in a Dispersive Cavity QED

    Institute of Scientific and Technical Information of China (English)

    GUOJian-Hong

    2003-01-01

    The interaction of N identical atoms with both a quantized cavity field and an external classical pumping field with the fields being degenerate in frequency, is studied in the regime where the atoms and fields are highly detuned. This dispersive interaction can be used to generate coherent states for the cavity field. By preparing the injected atoms in a superposition of the bare atomic states, various types of Schroedinger-cat-like states may be generated.

  2. Modulation instability in the weak dispersion regime of a dispersion modulated passive fiber-ring cavity.

    Science.gov (United States)

    Copie, François; Conforti, Matteo; Kudlinski, Alexandre; Trillo, Stefano; Mussot, Arnaud

    2017-05-15

    We present a theoretical and experimental study of the modulation instability process in a dispersion oscillating passive fiber-ring resonator in the low dispersion region. Generally, the modulation of the dispersion along the cavity length is responsible for the emergence of a regime characterised by multiple parametric resonances (or Faraday instabilities). We show that, under weak dispersion conditions, a huge number of Faraday sidebands can grow under the influence of fourth order dispersion. We specifically designed a piecewise uniform fiber-ring cavity and report on experiments that confirm our theoretical predictions. We recorded the dynamics of this system revealing strong interactions between the different sidebands in agreement with numerical simulations.

  3. Dual-etalon, cavity-ring-down, frequency comb spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Strecker, Kevin E.; Chandler, David W.

    2010-10-01

    The 'dual etalon frequency comb spectrometer' is a novel low cost spectometer with limited moving parts. A broad band light source (pulsed laser, LED, lamp ...) is split into two beam paths. One travels through an etalon and a sample gas, while the second arm is just an etalon cavity, and the two beams are recombined onto a single detector. If the free spectral ranges (FSR) of the two cavities are not identical, the intensity pattern at the detector with consist of a series of heterodyne frequencies. Each mode out of the sample arm etalon with have a unique frequency in RF (radio-frequency) range, where modern electronics can easily record the signals. By monitoring these RF beat frequencies we can then determine when an optical frequencies is absorbed. The resolution is set by the FSR of the cavity, typically 10 MHz, with a bandwidth up to 100s of cm{sup -1}. In this report, the new spectrometer is described in detail and demonstration experiments on Iodine absorption are carried out. Further we discuss powerful potential next generation steps to developing this into a point sensor for monitoring combustion by-products, environmental pollutants, and warfare agents.

  4. Cavity ring-down technique for measurement of reflectivity of high reflectivity mirrors with high accuracy

    Indian Academy of Sciences (India)

    G Sridhar; Sandeep K Agarwalla; Sunita Singh; L M Gantayet

    2010-12-01

    A simple, accurate and reliable method for measuring the reflectivity of laser-grade mirrors ( > 99.5 %) based on cavity ring-down (CRD) technique has been success-fully demonstrated in our laboratory using a pulsed Nd:YAG laser. A fast photomultiplier tube with an oscilloscope was used to detect and analyse the CRD signal. The cavity decay times were measured for three cavities formed by a combination of three mirror pairs. The absolute reflectivities 1, 2, 3 were determined to be 99.94%, 99.63%, 99.52% at normal incidence. The reflectivity of mirrors is measured to an accuracy of 0.01%.

  5. New limit on Lorentz violation using a double-pass optical ring cavity.

    Science.gov (United States)

    Michimura, Yuta; Matsumoto, Nobuyuki; Ohmae, Noriaki; Kokuyama, Wataru; Aso, Yoichi; Ando, Masaki; Tsubono, Kimio

    2013-05-17

    A search for Lorentz violation in electrodynamics was performed by measuring the resonant frequency difference between two counterpropagating directions of an optical ring cavity. Our cavity contains a dielectric element, which makes our cavity sensitive to the violation. The laser frequency is stabilized to the counterclockwise resonance of the cavity, and the transmitted light is reflected back into the cavity for resonant frequency comparison with the clockwise resonance. This double-pass configuration enables a null experiment and gives high common mode rejection of environmental disturbances. We found no evidence for odd-parity anisotropy at the level of δc/c ≲ 10(-14). Within the framework of the standard model extension, our result put more than 5 times better limits on three odd-parity parameters κ(o+)(JK) and a 12 times better limit on the scalar parameter κ(tr) compared with the previous best limits.

  6. 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

  7. Cavity-ring-down spectroscopy on water vapor in the range 555-604 nm

    NARCIS (Netherlands)

    Naus, H.; Ubachs, W.M.G.; Levelt, P.F.; Polyansky, O.L.; Zobov, N.F.; Tennyson, J.

    2001-01-01

    The method of pulsed cavity-ring-down spectroscopy was employed to record the water vapor absorption spectrum in the wavelength range 555-604 nm. The spectrum consists of 1830 lines, calibrated against the iodine standard with an accuracy of 0.01 cm(-1); 800 of these lines are not obtained in the HI

  8. Tunable bistability and asymmetric line shape in ring cavity-coupled Michelson interferometer

    Science.gov (United States)

    Li, Li; Zhang, Xinlu; Chen, Lixue

    2008-01-01

    A novel configuration of ring cavity-coupled Michelson interferometer is proposed to create sharp asymmetric multiple-resonance line shape, in which a ring cavity is side-coupled to one arm and a phase shifter is introduced into the other arm for static phase compensation. Such asymmetric line shape allows the tuning of the system between zero and complete transmission, with a phase offset much narrower than the full width of the cavity resonance itself. As tuning between resonance peak and notch of such asymmetric profile, optical transmission becomes much more sensitive to the round-trip phase shift of ring cavity than that in the case of symmetric Lorentzian line shape. By cooperating Kerr nonlinearity and cavity feedback, novel hysteresis loops and intrinsic bistability are achievable by adjusting incident power. The shapes of hysteresis curves associated with asymmetric resonance line shape are different from those arising from symmetric line shape. By adjusting the static phase compensation of phase shifter, tunable hysteresis loop and asymmetric multiple-resonance transmission can be easy performed. The simply constructed device is a good reference for sensitive optical switch, filter and sensor.

  9. Efficient generation of cylindrically polarized beams in an Yb:YAG thin-disk laser enabled by a ring-shaped pumping distribution

    Science.gov (United States)

    Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Abdou Ahmed, Marwan

    2016-04-01

    The efficient generation of a cylindrically (radially or azimuthally) polarized LG01 mode was investigated using a ring-shaped pumping distribution in a high-power Yb:YAG thin-disk laser setup. This was realized by implementing a 300 mm long customized fused silica fiber capillary in the pump beam path of the pumping optics of a thin-disk laser. Furthermore, a grating waveguide mirror based on the leaky-mode coupling mechanism was used as one of the cavity end mirrors to allow sufficient reduction of the reflectivity of the polarization state to be suppressed in the resonator. In order to achieve efficient laser operation, an optimized mode overlap between the ring-shaped pump spot and the excited first order Laguerre-Gaussian doughnut mode is required. This was investigated theoretically by analyzing the intensity distribution generated by different fiber geometries using a commercially raytracing software (Zemax). The output power, polarization state and efficiency of the emitted laser beam were compared to that obtained with a standard flattop pumping distribution. In particular, the thermal behavior of the disk was investigated since the excessive fluorescence caused by the non-saturated excitation in the center of the homogeneously pumped disk leads to a strong heating of the crystal. This considerable heating source is avoided in the case of the ring-shaped pumping and a reduction of the temperature increase on the disk surface of about 21% (at 280 W of pump power) was observed. This should allow higher pump power densities without increasing the risk of damaging the disk or distorting the polarization purity. With a laser efficiency of 41.2% to be as high as in the case of the flattop pumping, a maximum output power of 107 W was measured.

  10. Two-photon pumped cavity lasing in novel dye doped bulk matrix rods

    Science.gov (United States)

    He, Guang S.; Zhao, Chan F.; Bhawalkar, Jayant D.; Prasad, Paras N.

    1995-12-01

    Trans-4-[p-(N-ethyl-N-hydroxyethylamino)styryl]-N-methylpyridi that possesses a much greater two-photon absorption cross section and much stronger upconversion fluorescence emission than common organic dyes (such as rhodamine), when excited with near infrared laser radiation. Utilizing ASPT doped bulk polymer rods, two-photon pumped frequency upconverted cavity lasing has been accomplished using a Q-switched Nd:YAG laser as the pump source. The wavelength and pulse duration were ˜600 nm and 3-6 ns, respectively, for the cavity lasing; whereas the corresponding values for pump pulses were 1.06 μm and ˜10 ns, respectively. For a 7 mm long sample rod with a dopant concentration d0=8×10-3 M/L, the conversion efficiency from the absorbed pump energy to the cavity lasing output was ˜3.5% at a pump energy level of 1.3 mJ. The lasing lifetime, in terms of pulse numbers, was more than 4×104 pulses at 2 Hz repetition rate and room temperature.

  11. Comb-assisted cavity ring-down spectroscopy of a buffer-gas-cooled molecular beam.

    Science.gov (United States)

    Santamaria, Luigi; Sarno, Valentina Di; Natale, Paolo De; Rosa, Maurizio De; Inguscio, Massimo; Mosca, Simona; Ricciardi, Iolanda; Calonico, Davide; Levi, Filippo; Maddaloni, Pasquale

    2016-06-22

    We demonstrate continuous-wave cavity ring-down spectroscopy of a partially hydrodynamic molecular beam emerging from a buffer-gas-cooling source. Specifically, the (ν1 + ν3) vibrational overtone band of acetylene (C2H2) around 1.5 μm is accessed using a narrow-linewidth diode laser stabilized against a GPS-disciplined rubidium clock via an optical frequency comb synthesizer. As an example, the absolute frequency of the R(1) component is measured with a fractional accuracy of ∼1 × 10(-9). Our approach represents the first step towards the extension of more sophisticated cavity-enhanced interrogation schemes, including saturated absorption cavity ring-down or two-photon excitation, to buffer-gas-cooled molecular beams.

  12. Compact resonantly intra-cavity pumped tunable Ho:Sc2SiO5 laser

    Science.gov (United States)

    Yang, Xiao-tao; Song, En-zhe; Xie, Wen-qiang

    2017-09-01

    A compact intra-cavity pumped low threshold continuous-wave Ho:Sc2SiO5 laser is reported. The characteristics of output wavelength tuning are investigated by use a intra-cavity briefringent (BF) filter. A wavelength tunable range of 140 nm from 2020 to 2160 nm is achieved. For the free-running mode, the laser slope efficiency is 24.8%, when the output central wavelength is 2110 nm. The laser threshold is about 820 mW of incident pump power. With the BF filter, a maximum output power of 870 mW is obtained at the incident pump power of 5 W, corresponding to a slope efficiency of 20.3%. The characteristics of output wavelength verse the crystal temperature are also investigated.

  13. Normal mode splitting and mechanical effects of an optical lattice in a ring cavity

    CERN Document Server

    Klinner, J; Lindholdt, M; Nagorny, B; Hemmerich, Andreas; Klinner, Julian; Lindholdt, Malik; Nagorny, Boris

    2005-01-01

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detunedby about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  14. Normal Mode Splitting and Mechanical Effects of an Optical Lattice in a Ring Cavity

    Science.gov (United States)

    Klinner, Julian; Lindholdt, Malik; Nagorny, Boris; Hemmerich, Andreas

    2006-01-01

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far-detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detuned by about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  15. 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.

  16. Investigation on the fabrication of the 3rd harmonic superconducting cavity for the SSRF storage ring

    Institute of Scientific and Technical Information of China (English)

    MA Zhen-Yu; MA Guang-Ming; YU Hai-Bo; MAO Dong-Qing; FENG Zi-Qiang; HOU Hong-Tao; LIU Jian-Fei

    2009-01-01

    A third harmonic superconducting niobium cavity has been proposed for installation in the Shang-hai Synchrotron Radiation Facility (SSRF) storage ring to improve the Touschek lifetime. In order to investigate the feasibility of the superconducting cavity fabrication indigenously and the possibility to master the fabrica-tion techniques, cavities were fabricated from copper and niobium sheets by deep drawing and electron-beam welding, and a series of measurements, such as resonant frequency, shape dimensions and wall thickness, were carried out during this process. After analysis of various problems existing in the fabrication process, tech-nique improvements were proposed, and finally the precise shape as designed and resonant frequency within 1.2 MHz were achieved for the new completed cavities. In addition, full annealing was finally proved to be a good cure for niobium sheets' tearing up during deep drawing. By fabricating niobium cavities successfully, some problems to the next step were cleared. This paper introduces the process of cavity fabrication and its technique improvements towards forming, and the initial vertical test result of niobium cavity is also presented.

  17. Interplay of Touschek scattering, intrabeam scattering, and rf cavities in ultralow-emittance storage rings

    Directory of Open Access Journals (Sweden)

    S. C. Leemann

    2014-05-01

    Full Text Available The latest generation of storage ring-based light sources employs multibend achromat lattices to achieve ultralow emittance. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore, in such storage rings, parameters such as emittance, energy spread, and radiated power are—unlike 3rd generation storage rings—no longer constant during a typical user shift. Instead, they depend on several varying parameters such as insertion device gap settings, bunch charge, bunch length, etc. Since the charge per bunch is usually high, intrabeam scattering in medium-energy storage rings with ultralow emittance becomes very strong. This creates a dependence of emittance on stored current. Furthermore, since the bunch length is adjusted with rf cavities but is also varied as insertion device gaps change, the emittance blowup from intrabeam scattering is not constant either. Therefore, the emittance, bunch length, and hence the resulting Touschek lifetime have to be calculated in a self-consistent fashion with 6D tracking taking into account not only the bare lattice and rf cavity settings, but also momentary bunch charge and gap settings. Using the MAX IV 3 GeV storage ring as an example, this paper demonstrates the intricate interplay between transverse emittance (insertion devices, emittance coupling, longitudinal emittance (tuning of main cavities as well as harmonic cavities, and choice of stored current in an ultralow-emittance storage ring as well as some implications for brightness optimization.

  18. Influence of ring-down cavity parameters on intensity transmission property in trace gas concentration measurement

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-quan; YAN Ju-bing; SUN Yu-chao; LI Wen-chao

    2011-01-01

    In this paper,we describe the basic principles and system design of continuous wave cavity ring-down spectroscopy (CWCRDS).We also particularly study the nature and the behavior of a novel method to detune a laser and apply it to a cavity ring-down spectroscopy experiment.Both simulations and experiments are completed on the relation between the transmission characteristic and different reflectivities,as well as scanning speed.Output electric field equation is deduced.It has been investigated that how photons are coupled to the cavity and how to accumulate the intensity and leak out of the cavity as a function of time.It is noted that both accumulation of intensity and decay times decrease,and the oscillation amplitude increases as the reflectivity increases.Relative intensity increases with decreasing scanning velocity.Additionally,the simulations show that a non-detuned cavity displays the transmitted signals which are highly dependent on the mirror reflectivity and piezoelectric translator (PZT) modulation speed.Simulations also display that the laser switching off is different from detuning.

  19. Generation of single-frequency tunable green light in a coupled ring tapered diode laser cavity

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Petersen, Paul Michael

    2013-01-01

    We report the realization of a tapered diode laser operated in a coupled ring cavity that significantly improves the coherence properties of the tapered laser and efficiently generates tunable light at the second harmonic frequency. The tapered diode laser is tunable with single-frequency output...... frequency doubling. More than 500 mW green output power is obtained by placing a periodically poled LiNbO3 crystal in the external cavity. The single frequency green output from the laser system is tunable in the 530 nm to 533 nm range limited by the LiNbO3 crystal. The optical to optical conversion...

  20. Dynamics of Turing and Faraday instabilities in a longitudinally modulated fiber-ring cavity.

    Science.gov (United States)

    Copie, F; Conforti, M; Kudlinski, A; Trillo, S; Mussot, A

    2017-02-01

    We experimentally investigate the round-trip-to-round-trip dynamics of the modulation instability spectrum in a passive fiber-ring cavity presenting an inhomogeneous dispersion profile. By implementing a real-time spectroscopy technique, we are able to record successive single-shot spectra, which display the evolution of the system toward a stationary state. We find that the two instability regimes (Turing and Faraday) that compete in this kind of inhomogeneous cavity not only differ by their characteristic frequency but also by their dynamical behavior. The dynamic transition between those two regimes of instability is also presented.

  1. Backaction-driven transport of Bloch oscillating atoms in ring cavities.

    Science.gov (United States)

    Goldwin, J; Venkatesh, B Prasanna; O'Dell, D H J

    2014-08-15

    We predict that an atomic Bose-Einstein condensate strongly coupled to an intracavity optical lattice can undergo resonant tunneling and directed transport when a constant and uniform bias force is applied. The bias force induces Bloch oscillations, causing amplitude and phase modulation of the lattice which resonantly modifies the site-to-site tunneling. For the right choice of parameters a net atomic current is generated. The transport velocity can be oriented oppositely to the bias force, with its amplitude and direction controlled by the detuning between the pump laser and the cavity. The transport can also be enhanced through imbalanced pumping of the two counterpropagating running wave cavity modes. Our results add to the cold atoms quantum simulation toolbox, with implications for quantum sensing and metrology.

  2. Cavity modes with optical orbital angular momentum in a metamaterial ring based on transformation optics.

    Science.gov (United States)

    Wu, H W; Wang, F; Dong, Y Q; Shu, F Z; Zhang, K; Peng, R W; Xiong, X; Wang, Mu

    2015-12-14

    In this work, we theoretically study the cavity modes with transverse orbital angular momentum in metamaterial ring based on transformation optics. The metamaterial ring is designed to transform the straight trajectory of light into the circulating one by enlarging the azimuthal angle, effectively presenting the modes with transverse orbital angular momentum. The simulation results confirm the theoretical predictions, which state that the transverse orbital angular momentum of the mode not only depends on the frequency of the incident light, but also depends on the transformation scale of the azimuthal angle. Because energy dissipation inevitably reduces the field amplitude of the modes, the confined electromagnetic energy and the quality factor of the modes inside the ring are also studied in order to evaluate the stability of those cavity modes. The results show that the metamaterial ring can effectively confine light with a high quality factor and maintain steady modes with the orbital angular momentum, even if the dimension of the ring is much smaller than the wavelength of the incident light. This technique for exploiting the modes with optical transverse orbital angular momentum may provides a unique platform for applications related to micromanipulation.

  3. Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy

    CERN Document Server

    De Vine, G; Close, J D; Gray, M B; Vine, Glenn de; Clelland, David E. Mc; Close, John D.; Gray, Malcolm B.

    2004-01-01

    We present an experimental technique enabling mechanical-noise free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532nm frequency doubled output from a Nd:YAG laser and an iodine vapour cell. The cell is placed in a traveling-wave Fabry-Perot interferometer (FPI) with counter-propagating pump and probe beams. The FPI is locked using the Pound-Drever-Hall (PDH) technique. Mechanical noise is rejected by differencing pump and probe signals. In addition, this differenced error signal gives a sensitive measure of differential non-linearity within the FPI.

  4. Chiral cavity ring down polarimetry: Chirality and magnetometry measurements using signal reversals

    Energy Technology Data Exchange (ETDEWEB)

    Bougas, Lykourgos; Sofikitis, Dimitris; Katsoprinakis, Georgios E.; Spiliotis, Alexandros K.; Rakitzis, T. Peter, E-mail: ptr@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, 71003 Heraklion, Crete (Greece); Tzallas, Paraskevas; Loppinet, Benoit [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion, Crete (Greece)

    2015-09-14

    We present the theory and experimental details for chiral-cavity-ring-down polarimetry and magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by the presence of both chiral and Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. We present the measurement of the specific rotation at 800 nm of vapors of α-pinene, 2-butanol, and α-phellandrene, the measurement of optical rotation of sucrose solutions in a flow cell, the measurement of the Verdet constant of fused silica, and measurements and theoretical treatment of evanescent-wave optical rotation at a prism surface. Therefore, these signal-enhancing and signal-reversing methods open the way for ultrasensitive polarimetry measurements in gases, liquids and solids, and at surfaces.

  5. Chiral cavity ring down polarimetry: Chirality and magnetometry measurements using signal reversals.

    Science.gov (United States)

    Bougas, Lykourgos; Sofikitis, Dimitris; Katsoprinakis, Georgios E; Spiliotis, Alexandros K; Tzallas, Paraskevas; Loppinet, Benoit; Rakitzis, T Peter

    2015-09-14

    We present the theory and experimental details for chiral-cavity-ring-down polarimetry and magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by the presence of both chiral and Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. We present the measurement of the specific rotation at 800 nm of vapors of α-pinene, 2-butanol, and α-phellandrene, the measurement of optical rotation of sucrose solutions in a flow cell, the measurement of the Verdet constant of fused silica, and measurements and theoretical treatment of evanescent-wave optical rotation at a prism surface. Therefore, these signal-enhancing and signal-reversing methods open the way for ultrasensitive polarimetry measurements in gases, liquids and solids, and at surfaces.

  6. A laser feedback control design for passive ring laser gyros in a very high finesse cavity

    Science.gov (United States)

    Lorenz, M. A.

    1985-12-01

    The Frank J. Seiler Research Laboratory is currently developing a Passive Resonant Ring Laser Gyroscope (PRRLG) enclosing 58 sq m for proposed use in testing high precision rate sensors and for possibly validating the Theory of General Relativity. The sensitivities required for such experiments are in the 10 to the minus 7th power to 10 to the minus 10th power Earth Rate Unit (ERU) range. This high sensitivity necessitates the use of a large, high finesse cavity. In dealing with high finesse cavities new considerations arise. For example, the cavity linewidth is narrower than linewidths of commercially available stabilized He-Ne lasers. The stability of the laser then becomes the limiting factor in the performance of the PRRLG because of the increased signal-to-noise ratio that arises in this situation. In addition, high finesse cavities exhibit photon lifetimes on the order of 10 to the minus 3rd power to 10 to the minus 6th power seconds, which limits the bandwidth of practical controllers. In this research, a PRRLG was constructed in which a He-Ne laser was frequency locked to 25,000 finesse, 169 sq. cm. resonant cavity, as opposed to the more traditional technique of locking the resonant condition of the cavity to the laser frequency.

  7. Quantifying Carbon-14 for Biology Using Cavity Ring-Down Spectroscopy

    OpenAIRE

    McCartt, A. Daniel; Ognibene, Ted J.; Bench, Graham; Turteltaub, Kenneth W.

    2016-01-01

    A cavity ring-down spectroscopy (CRDS) instrument was developed using mature, robust hardware for the measurement of carbon-14 in biological studies. The system was characterized using carbon-14 elevated glucose samples and returned a linear response up to 387 times contemporary carbon-14 concentrations. Carbon-14 free and contemporary carbon-14 samples with varying carbon-13 concentrations were used to assess the method detection limit of approximately one-third contemporary carbon-14 levels...

  8. Compact near-IR and mid-IR cavity ring down spectroscopy device

    Science.gov (United States)

    Miller, J. Houston (Inventor)

    2011-01-01

    This invention relates to a compact cavity ring down spectrometer for detection and measurement of trace species in a sample gas using a tunable solid-state continuous-wave mid-infrared PPLN OPO laser or a tunable low-power solid-state continuous wave near-infrared diode laser with an algorithm for reducing the periodic noise in the voltage decay signal which subjects the data to cluster analysis or by averaging of the interquartile range of the data.

  9. Half-period Aharonov-Bohm oscillations in disordered rotating optical ring cavities

    CERN Document Server

    Li, Huanan; Shapiro, Boris

    2016-01-01

    There exists an analogy between Maxwell equations in a rotating frame and Schr\\"odinger equation for a charged particle in the presence of a magnetic field. We exploit this analogy to point out that electromagnetic phenomena in the rotating frame, under appropriate conditions, can exhibit periodicity with respect to the angular velocity of rotation. In particular, in disordered ring cavities one finds the optical analog of the Al'tshuler-Aronov-Spivak effect well known in mesoscopic physics of disordered metals.

  10. Discrete Frequency Entangled Photon Pair Generation Based on Silicon Micro-ring Cavities

    Science.gov (United States)

    Suo, Jing; Zhang, Wei; Dong, Shuai; Huang, Yidong; Peng, Jiangde

    2016-10-01

    In this paper, we propose and demonstrate a scheme to generate discrete frequency entangled photon pairs based on a silicon micro-ring resonator. The resonator is placed in a Sagnac fiber loop. Stimulated by two pump lights at two different resonance wavelengths of the resonator, photon pairs at another two resonance wavelengths are generated along two opposite directions in the fiber loop, by the nondegenerate spontaneous four wave mixing in the resonator. Their states are superposed and interfered at the output ports of the fiber loop to generate frequency entangled photon pairs. On the other hand, since the pump lights come from two continuous wave lasers, energy-time entanglement is an intrinsic property of the generated photon pairs. The entanglements on frequency and energy-time are demonstrated experimentally by the experiments of spatial quantum beating and Franson-type interference, respectively, showing that the silicon micro-ring resonators are ideal candidates to realize complex photonic quantum state generation.

  11. Single-particle-excitation spectrum of degenerate Fermi gases in a ring cavity

    Science.gov (United States)

    Feng, Chao; Chen, Yu

    2017-09-01

    By considering spin-1/2 degenerate Fermi gases in a ring cavity where strong interaction between atoms and light gives rise to superradiance, we find that the cavity dissipation can cause a severe broadening in some special cases, breaking down the quasiparticle picture which has been constantly assumed in mean-field theory studies. This broadening happens when the band gap is resonant with polariton excitation energy. Interestingly enough, this broadening is highly spin selective, depending on how the fermions are filled, and the spectrum becomes asymmetric due to dissipation. Further, a nonmonotonous dependence of the maximal broadening of the spectrum on the cavity decay rate κ is found and the largest broadening emerges at κ , comparable to the recoil energy.

  12. Ultrasensitive, self-calibrated cavity ring-down spectrometer for quantitative trace gas analysis.

    Science.gov (United States)

    Chen, Bing; Sun, Yu R; Zhou, Ze-Yi; Chen, Jian; Liu, An-Wen; Hu, Shui-Ming

    2014-11-10

    A cavity ring-down spectrometer is built for trace gas detection using telecom distributed feedback (DFB) diode lasers. The longitudinal modes of the ring-down cavity are used as frequency markers without active-locking either the laser or the high-finesse cavity. A control scheme is applied to scan the DFB laser frequency, matching the cavity modes one by one in sequence and resulting in a correct index at each recorded spectral data point, which allows us to calibrate the spectrum with a relative frequency precision of 0.06 MHz. Besides the frequency precision of the spectrometer, a sensitivity (noise-equivalent absorption) of 4×10-11  cm-1  Hz-1/2 has also been demonstrated. A minimum detectable absorption coefficient of 5×10-12  cm-1 has been obtained by averaging about 100 spectra recorded in 2  h. The quantitative accuracy is tested by measuring the CO2 concentrations in N2 samples prepared by the gravimetric method, and the relative deviation is less than 0.3%. The trace detection capability is demonstrated by detecting CO2 of ppbv-level concentrations in a high-purity nitrogen gas sample. Simple structure, high sensitivity, and good accuracy make the instrument very suitable for quantitative trace gas analysis.

  13. Properties of two-photon pumped cavity lasing in novel dye doped solid matrices

    Energy Technology Data Exchange (ETDEWEB)

    He, G.S.; Bhawalkar, J.D.; Zhao, C.; Prasad, P.N. [State Univ. of New York, Buffalo, NY (United States). Dept. of Chemistry

    1996-05-01

    Two-photon pumped frequency upconversion cavity lasing at {approximately}600 nm is accomplished in three types of dye-doped solid rods pumped with {approximately}10 ns and 1.06-{micro}m IR laser pulses. The dopant is a new dye, trans-4-[p-(N-ethyl-N-(hydroxyethyl)amino)styryl]-N-methylpyridinium tetraphenylborate, abbreviated as ASPT, which possesses a greater two-photon absorption cross section and stronger upconversion fluorescence emission than common commercial dyes (such as rhodamine). Three different materials were chosen as solid matrices: poly(2-hydroxyethyl methacrylate), VYCOR porous glass, and sol-gel glass. Using a Q-switched Nd:YAG pulse laser as the pump source, strong cavity lasing could be achieved in these three ASPT doped solid rods as well as in ASPT solution in a liquid cell. The spectral, temporal, and spatial characteristics of the cavity lasing output have been systematically investigated. The measured output-input characteristics, lasing lifetime, and damage threshold for the three different rods are presented.

  14. Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

    Institute of Scientific and Technical Information of China (English)

    Qing Wang(王青); Chunqing Gao(高春清); Yan Zhao(赵严); Suhui Yang(杨苏辉); Guanghui Wei(魏光辉); Dongmei Hong(洪冬梅)

    2003-01-01

    Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystalwith a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-μm fiber coupledlaser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiencywas 16%. With a 100-μm fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser wasobtained with a slope efficiency of 29%.

  15. High-Reliability Pump Module for Non-Planar Ring Oscillator Laser

    Science.gov (United States)

    Liu, Duncan T.; Qiu, Yueming; Wilson, Daniel W.; Dubovitsky, Serge; Forouhar, Siamak

    2007-01-01

    We propose and have demonstrated a prototype high-reliability pump module for pumping a Non-Planar Ring Oscillator (NPRO) laser suitable for space missions. The pump module consists of multiple fiber-coupled single-mode laser diodes and a fiber array micro-lens array based fiber combiner. The reported Single-Mode laser diode combiner laser pump module (LPM) provides a higher normalized brightness at the combined beam than multimode laser diode based LPMs. A higher brightness from the pump source is essential for efficient NPRO laser pumping and leads to higher reliability because higher efficiency requires a lower operating power for the laser diodes, which in turn increases the reliability and lifetime of the laser diodes. Single-mode laser diodes with Fiber Bragg Grating (FBG) stabilized wavelength permit the pump module to be operated without a thermal electric cooler (TEC) and this further improves the overall reliability of the pump module. The single-mode laser diode LPM is scalable in terms of the number of pump diodes and is capable of combining hundreds of fiber-coupled laser diodes. In the proof-of-concept demonstration, an e-beam written diffractive micro lens array, a custom fiber array, commercial 808nm single mode laser diodes, and a custom NPRO laser head are used. The reliability of the proposed LPM is discussed.

  16. Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation

    Directory of Open Access Journals (Sweden)

    Houlin Liu

    2014-04-01

    Full Text Available The leakage flow paths in the sidewall gaps of centrifugal pumps are of significant importance for numbers of effects. The paper is concerned with the transient flow in the leakage flow paths with wear ring clearance variation. For this purpose, numerical simulations of the whole pump were carried out. The grid dependence and yplus check were performed first. Additionally, experimental data of performance characteristic and pressure fluctuation inside the sidewall gap was used to validate the numerical results. The transient velocity fields inside the sidewall gaps during one blade passage period were simulated. And the leakage through the wear ring gap was obtained for all operating points investigated. To have a better idea of attenuation and propagation of pressure inside the sidewall gap, the unsteady pressure distributions in the gap were calculated. Additionally, the surfaces of the impeller were divided into four parts. The fluid force on each part was expressed as a percentage of the total radial force. Through comparing the flow fields, the pressure distributions, and the radial force between the pumps with different wear ring clearances, the effects of the wear ring clearance were discussed in detail. The results can be used to guide the optimum design of the pump sidewall gaps.

  17. Cavity Ring Down Absorption of Oxygen in Air as a Temperature Sensor

    Science.gov (United States)

    Manzanares, Carlos; Nyaupane, Parashu R.

    2016-06-01

    The A-band of oxygen has been measured at low resolution at temperatures between 90 K and 373 K using the phase shift cavity ring down (PS-CRD) technique. For temperatures between 90 K and 295 K, the PS-CRD technique presented here involves an optical cavity attached to a cryostat. The static cell and mirrors of the optical cavity are all inside a vacuum chamber at the same temperature of the cryostat. The temperature of the cell can be changed between 77 K and 295 K. For temperatures above 295 K, a hollow glass cylindrical tube without windows has been inserted inside an optical cavity to measure the temperature of air flowing through the tube. The cavity consists of two highly reflective mirrors which are mounted parallel to each other and separated by a distance of 93 cm. In this experiment, air is passed through a heated tube. The temperature of the air flowing through the tube is determined by measuring the intensity of the oxygen absorption as a function of the wavenumber. The A-band of oxygen is measured between 298 K and 373 K, with several air flow rates. Accuracy of the temperature measurement is determined by comparing the calculated temperature from the spectra with the temperature obtained from a calibrated thermocouple inserted at the center of the tube.

  18. Formation of a 6FDA-based ring polyimide with nanoscale cavity evaluated by DFT calculations

    Science.gov (United States)

    Fukuda, Mitsuhiro; Takao, Yoshimi; Tamai, Yoshinori

    2005-04-01

    The computer-aided molecular design of a rigid ring molecule has been performed. As a candidate molecule, the polyimide derived from 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) with m-phenylenediamine (MDA) has been used. The optimized structures of the 6FDA-MDA model compounds including a precursor type amic acid model were investigated using the density functional theory (DFT) at the B3LYP/6-311G(d,p) level. Using the optimized structures of the model compounds, the probable combinations to form a flat ring polyimide are considered by taking the spatial angles between the respective aromatic groups into consideration. We selected several combinations with different conformations and the number of monomer units. We showed that the dimer, trimer and tetramer of not only the 6FDA-based ring imide but also the corresponding ring amic acid can have a stable geometry. Each of them contains a cavity of sub-nanometer size and characteristic shape. Among them, the interaction energy with some guest molecules are evaluated for the smallest ring imide constructed from two units of 6FDA-MDA using the DFT calculations.

  19. Chemical Sensing Using Infrared Cavity Enhanced Spectroscopy: Short Wave Infrared Cavity Ring Down Spectroscopy (SWIR CRDS) Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Richard M.; Harper, Warren W.; Aker, Pam M.; Thompson, Jason S.; Stewart, Timothy L.

    2003-10-01

    The principal goal of Pacific Northwest National Laboratory's (PNNL's) Remote Spectroscopy Project is to explore and develop the science and technology behind point and stand off infrared (IR) spectroscopic chemical sensors that are needed for detecting weapons proliferation activity and countering terrorism. Missions addressed include detecting chemical, biological, and nuclear weapons and their production; counter terrorism measures that involve screening luggage, personnel, and shipping containers for explosives, firearms, narcotics, chemical weapons and/or their residues; and mapping of contaminated areas. The science and technology developed in this program is dual use in that it additionally supports progress in a diverse set of agendas that include chemical weapons defense programs, air operations activities, emissions monitoring, law enforcement, and medical diagnostics. Sensors for these missions require extremely low limits of detection because many of the targeted signature species are either present in low concentrations or have extremely low vapor pressures. The sensors also need to be highly selective as the environments that they will be operated in will contain a variety of interferent species and false positive detection is not an option. PNNL has been working on developing a class of sensors that draw vapor into optical cavities and use laser-based spectroscopy to identify and quantify the vapor chemical content. The cavity enhanced spectroscopies (CES) afford extreme sensitivity, excellent selectivity, noise immunity, and rapid, real-time, in-situ chemical characterization. PNNL's CES program is currently focused on developing two types of sensors. The first one, which is based on cavity ring down spectroscopy (CRDS), uses short wave infrared (SWIR) lasers to interrogate species. The second sensor, which is based on noise immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE OHMS), uses long wave infrared (LWIR

  20. RF cavity R&D at LBNL for the NLC damping rings, FY1999

    Energy Technology Data Exchange (ETDEWEB)

    Rimmer, R.A.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.

    1999-11-01

    This report contains a summary of the R&D activities at LBNL on RF cavities for the NLC damping rings during fiscal year19999. These activities include the optimization of the RF design for both efficiency and damping of higher-order (HOMs), by systematic study of the cavity profile, the effect of the beam pipe diameter, nosecone angle and gap, the cross section and position of the HOM damping waveguides and the coupler. The effect of the shape of the HOM waveguides and their intersection with the cavity wall on the local surface heating is also an important factor, since it determines the highest stresses in the cavity body. This was taken into account during the optimization so that the stresses could be reduced at the same time as the HOP damping was improved over previous designs. A new method of calculating the RF heating was employed, using a recently released high frequency electromagnetic element in ANSYS. This greatly facilitates the thermal and stress analysis of the design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. Preliminary designs are described for the cavity ancillary components including the RF window, HOM loads, and tuners. A preliminary manufacturing plan is included, with an initial estimate of the resource requirements. Other cavity options are discussed which might be desirable to either lower the R/Q, for reduced transient response, or lower the residual HOM impedance to reduce coupled-bunch growth rates further still.

  1. Bidirectional oscillations in Er-doped fiber ring cavity with polarization splitting for rotation sensing

    Science.gov (United States)

    Rao, Fan-Jun; Chen, Shu-fen; Fu, Lei

    2011-03-01

    The structure of an all-fiber Erbium-doped fiber ring cavity with bidirectional single-mode oscillations and a rotation-sensitive beat signal for gyro applications is reported in this letter. The structure is achieved by introducing a polarization splitting method to filter the bidirectional oscillations and to control the mode coupling of the counter-propagating waves. Two distinct behaviors of the beat signal are identified, namely, the linear mode coupling situation caused by the back-reflection of the optical elements and the nonlinear mode coupling situation attributed to spatially non-uniform saturation in gain medium. Experiments are conducted to show the cavity rotation rate dependence of the beat frequency shift. The results are in good agreement with the theoretical predictions.

  2. Micro-ring resonator quality factor enhancement via an integrated Fabry-Perot cavity

    Directory of Open Access Journals (Sweden)

    Jiayang Wu

    2017-05-01

    Full Text Available We propose and experimentally demonstrate the enhancement in the filtering quality (Q factor of an integrated micro-ring resonator (MRR by embedding it in an integrated Fabry-Perot (FP cavity formed by cascaded Sagnac loop reflectors. By utilizing coherent interference within the FP cavity to reshape the transmission spectrum of the MRR, both the Q factor and the extinction ratio (ER can be significantly improved. The device is theoretically analyzed and practically fabricated on a silicon-on-insulator wafer. Experimental results show that up to 11-times improvement in the Q factor, together with an 8-dB increase in the ER, can be achieved via our proposed method. The impact of varying structural parameters on the device performance is also investigated and verified by the measured spectra of the fabricated devices with different structural parameters.

  3. Symmetry Breaking of Frequency Comb in Varying Normal Dispersion Fiber Ring Cavity

    CERN Document Server

    Afzal, Muhammad Imran; Lee, Yong Tak

    2016-01-01

    We build on a previously reported frequency comb of mode spacing 0.136 nm in a fiber ring cavity of varying normal dispersion [1], to generate, for the first time, a frequency comb of mode spacing 0.144 nm centered at 978.544 nm to demonstrate the symmetry-breaking. By controlling the birefringence of the optical cavity through fiber stretching and polarization control, the spacing of the comb lines increases from 0.136 nm to 0.144 nm, and this small change in mode spacing generates very different spectral symmetry-breaking in the frequency comb relative to the frequency comb of mode spacing 0.136 nm. Interestingly, non-uniform depletion of primary modes is also observed. The experimental results are an important contribution in the continuing effort of understanding the dynamics of frequency combs involving large number of modes, nontrivial nonlinear waves and deterministic chaos.

  4. Dual-etalon cavity ring-down frequency-comb spectroscopy with broad band light source

    Science.gov (United States)

    Chandler, David W; Strecker, Kevin E

    2014-04-01

    In an embodiment, a dual-etalon cavity-ring-down frequency-comb spectrometer system is described. A broad band light source is split into two beams. One beam travels through a first etalon and a sample under test, while the other beam travels through a second etalon, and the two beams are recombined onto a single detector. If the free spectral ranges ("FSR") of the two etalons are not identical, the interference pattern at the detector will consist of a series of beat frequencies. By monitoring these beat frequencies, optical frequencies where light is absorbed may be determined.

  5. Half-period Aharonov-Bohm oscillations in disordered rotating optical ring cavities

    Science.gov (United States)

    Li, Huanan; Kottos, Tsampikos; Shapiro, Boris

    2016-09-01

    There exists an analogy between Maxwell equations in a rotating frame and the Schrödinger equation for a charged particle in the presence of a magnetic field. We exploit this analogy to point out that electromagnetic phenomena in the rotating frame, under appropriate conditions, can exhibit periodicity with respect to the angular velocity of rotation. In particular, in disordered ring cavities one finds the optical analog of the Al'tshuler-Aronov-Spivak effect well known in mesoscopic physics of disordered metals.

  6. Chiral Symmetry Breaking in Micro-Ring Optical Cavity By Engineered Dissipation

    CERN Document Server

    Shu, Fang-Jie; Zou, Xu-Bo; Yang, Lan

    2016-01-01

    We propose a method to break the chiral symmetry of light in traveling wave resonators by coupling the optical modes to a lossy channel. Through the engineered dissipation, an indirect dissipative coupling between two oppositely propagating modes can be realized. Combining with reactive coupling, it can break the chiral symmetry of the resonator, allowing light propagating only in one direction. The chiral symmetry breaking is numerically verified by the simulation of an electromagnetic field in a micro-ring cavity, with proper refractive index distributions. This work provokes us to emphasize the dissipation engineering in photonics, and the generalized idea can also be applied to other systems.

  7. 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.

  8. 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.

  9. Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Ward, Jonathan M; Chormaic, Síle Nic

    2016-01-01

    In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady state transmission spectrum through the coupling waveguide. Alternatively, cavity ring-up spectroscopy (CRUS) sensing can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh \\textit{Q}-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which might improve the data collection rate.

  10. Improved Optical Magnetometer Based on Electromagnetically Induced Transparency in a Ring-Cavity Setup

    Science.gov (United States)

    Bardhan, Bhaskar Roy; Kim, Moochan; Dowling, Jonathan

    2012-06-01

    We propose and simulate a ring-gyro optical magnetometer based on polarization rotation of an optical field in an electromagnetically induced transparency (EIT) system. By properly choosing the polarization orientations of the optical field and the transition energy levels, the transparency conditions for the polarization components are derived for the EIT system inserted into the ring-cavity setup as a cell. As the optical field passes through the cell, the fluctuations of the Rabi frequency as well as the density inside the cell, due to the fluctuations in the laser field, give rise to the dephasing of the polarization vector. We show that using the setup it is possible to achieve very sensitive measurement of the magnetic field. Besides, by making several round trips of the photons, the dephasing effects can be removed by some suitable dynamical decoupling schemes implemented with additional waveplates in the setup. This enables us to obtain long interrogation length for the EIT based optical magnetometer.

  11. Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped

    Science.gov (United States)

    Yan, Boxia; Qi, Yan; Wang, Yanwei

    2016-10-01

    Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

  12. A continuous stream flash evaporator for the calibration of an IR cavity ring down spectrometer for isotopic analysis of water

    CERN Document Server

    Gkinis, Vasileios; Johnsen, Sigfus J; Blunier, Thomas

    2014-01-01

    A new technique for high resolution simultaneous isotopic analysis of $\\delta^{18}\\mathrm{O}$ and $\\delta\\mathrm{D}$ in liquid water is presented. A continuous stream flash evaporator has been designed that is able to vaporise a stream of liquid water in a continuous mode and deliver a stable and finely controlled water vapour sample to a commercially available Infra Red Cavity Ring Down Spectrometer. Injection of sub $\\mu l$ amounts of the liquid water is achieved by pumping liquid water sample through a fused silica capillary and instantaneously vaporising it with a 100% efficiency in a home made oven at a temperature of $170 ^{o}$C. The system's simplicity, low power consumption and low dead volume together with the possibility for automated unattended operation, provides a solution for the calibration of laser instruments performing isotopic analysis of water vapour. Our work is mainly driven by the possibility to perform high resolution on line water isotopic analysis on Continuous Flow Analysis systems ...

  13. 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.

  14. Electromagnetic analysis of optimal pumping of a microdisk laser with a ring electrode

    Science.gov (United States)

    Zolotukhina, Anna S.; Spiridonov, Alexander O.; Karchevskii, Evgenii M.; Nosich, Alexander I.

    2017-01-01

    We study the lasing modes of microdisk lasers with ring-like electrodes or active regions, in two-dimensional (2-D) formulation. The considered eigenvalue problem is adapted to the extraction of both modal spectra and thresholds from the Maxwell equations with exact boundary conditions. We reduce it to a transcendental equation and solve it numerically. The obtained lasing frequencies and the associated values of threshold material gain of the ring-pumped laser are compared with similar quantities of the fully active microdisk. This comparison shows that the optimal position of the active ring is shifted inward from the disk rim. Its location and width can be used as an engineering instrument to manipulate the thresholds. This effect is explained using the optical theorem and overlap coefficients.

  15. The progressing cavity pump operating envelope : you cannot expand what you don't understand

    Energy Technology Data Exchange (ETDEWEB)

    Noonan, S.G. [ConocoPhillips Co., Houston, TX (United States)

    2008-10-15

    For years, the preferred method of lift for cold heavy oil production has been progressing cavity pumps (PCP) but their use has resulted in many misapplications and poor performance. Testing programs have since emerged to understand the science behind PCP performance under different conditions. This paper described some of the recent findings from these test programs in order to assist in selecting and designing a PCP system for heavy oil, including understanding gas handling capabilities, rod string torsion, elastomer swell, metallic stators, and the effects of speed and rotor-stator fit on PCP run life. The paper also described the efforts of a group of operating companies to standardize nomenclature and data parameters in order to facilitate analysis and benchmarking to identify areas for improvement and gaps for technology advancement. Information from a group of PCP users and manufacturers that created comprehensive international standards in 2006 and recommended practices for the manufacturing and testing of these pumping systems were also provided. It was concluded that much is still needed to be understood in understanding PCP performance, especially drive string dynamics, pump pressure capability, and PCP system reliability. 18 refs., 2 figs.

  16. A contracting circumbinary molecular ring with an inner cavity of about 140 AU around Ori 139-409

    CERN Document Server

    Zapata, Luis A; Ho, Paul

    2009-01-01

    Sensitive and subarcsecond resolution ($\\sim$ 0.7\\arcsec) CH$_3$OH(7$_{-2,6}$ $\\to$ 6$_{-2,5}$) line and 890 $\\mu$m continuum observations made with the Submillimeter Array (SMA) towards the hot molecular circumbinary ring associated with the young multiple star Ori 139-409 are presented. The CH$_3$OH(7$_{-2,6}$ - 6$_{-2,5}$) emission from the ring is well resolved at this angular resolution revealing an inner cavity with a size of about 140 AU. A LTE model of a Keplerian disk with an inner cavity of the same size confirms the presence of this cavity. Additionally, this model suggests that the circumbinary ring is contracting with a velocity of V$_{inf}$ $\\sim$ 1.5 km s$^{-1}$ toward the binary central compact circumstellar disks reported at a wavelength of 7 mm. {\\bf The inner central cavity seems to be formed by the tidal effects of the young stars in the middle of the ring.} The ring appears to be not a stationary object. Furthermore, the infall velocity we determine is about a factor of 3 slower than the ...

  17. Sub-picosecond pulse generation employing an SOA-based nonlinear polarization switch in a ring cavity.

    Science.gov (United States)

    Yang, X; Li, Z; Tangdiongga, E; Lenstra, D; Khoe, G; Dorren, H

    2004-05-31

    We demonstrate the generation of sub-picosecond optical pulses using a semiconductor optical amplifier (SOA) and a linear polarizer placed in a ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the passive mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz. The time -bandwidth product is 0.48. Simulation results in good agreement with the experimental results are presented.

  18. SUBJOULE DIODE-PUMPED YTTERBIUM-ERBIUM GLASS LASER WITH CAVITY DUMPING FOR CATARACT EXTRACTION

    Directory of Open Access Journals (Sweden)

    A. V. Belikov

    2015-11-01

    Full Text Available Subject of Study. The paper discusses the breadboarding results of compact diode pumped laser. The laser is based on Yb,Er:glass slab active element and frustrated total internal reflection (FTIR shutter and features of the impact of generated pulses at the water-containing media. The transmitter working in cavity dumping mode provides generation of single microsecond pulses or regular trains of these pulses with peak power up to 100 kW and average output power up to 8 W. The laser allows varying output parameters of radiation in wide range and is designed for the usage in technology and biomedical applications. The possibilities of the laser radiation parameters adapting for application in a compact laser cataract extraction complex are examined. Method. The energy efficient for three level active medium method of lasing pulses repetition rate increasing was investigated, which comprises the generation of pulse trains by several FTIR shutter switching on one pump pulse. We carried out analysis of application possibility for microsecond laser pulses with peak power of tens of kilowatts at wavelength of 1,54 μm in the processing of water-containing tissues. The acoustic response on the interaction of radiation with a model environment was studied. Main Results. In the modulation mode of useful (active losses lasing pulses have been obtained with microsecond duration and energy more than 100 mJ and trains of pulses with total energy of 0,5 J at the effective pulse repetition rate of more than 50 Hz. The minimal permissible period of laser pulses in train (300 μs has been established experimentally on the basis of optoacoustic studies. It meets the criteria of operation noninvasiveness consisting in prevention of the risk of posterior lens capsule damage with laser radiation. Practical Relevance. The results obtained with the layout of diode pumped Yb,Er:glass laser with cavity dumping and slab active element are presently record for diode-pumped

  19. Codimension 2 and 3 situations in a ring cavity with elliptically polarized electromagnetic waves

    CERN Document Server

    Martin, D A

    2015-01-01

    We study pattern formation on the plane transverse to propagation direction, in a ring cavity filled with a Kerr-like medium, subject to an elliptically polarized incoming field, by means of two coupled Lugiato-Lefever equations. We consider a wide range of possible values for the coupling parameter between different polarizations, *B*, as may happen in composite materials. Positive and also negative refraction index materials are considered. Examples of marginal instability diagrams are shown. It is shown that, within the model, instabilities cannot be of codimension higher than 3. A method for finding parameters for which codimension 2 or 3 takes place is given. The method allows us to choose parameters for which unstable wavenumbers fulfill different relations. Numerical integration results where different instabilities coexist and compete are shown.

  20. Quantifying Carbon-14 for Biology Using Cavity Ring-Down Spectroscopy.

    Science.gov (United States)

    McCartt, A Daniel; Ognibene, Ted J; Bench, Graham; Turteltaub, Kenneth W

    2016-09-06

    A cavity ring-down spectroscopy (CRDS) instrument was developed using mature, robust hardware for the measurement of carbon-14 in biological studies. The system was characterized using carbon-14 elevated glucose samples and returned a linear response up to 387 times contemporary carbon-14 concentrations. Carbon-14 free and contemporary carbon-14 samples with varying carbon-13 concentrations were used to assess the method detection limit of approximately one-third contemporary carbon-14 levels. Sources of inaccuracies are presented and discussed, and the capability to measure carbon-14 in biological samples is demonstrated by comparing pharmacokinetics from carbon-14 dosed guinea pigs analyzed by both CRDS and accelerator mass spectrometry. The CRDS approach presented affords easy access to powerful carbon-14 tracer techniques that can characterize complex biochemical systems.

  1. Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

    Directory of Open Access Journals (Sweden)

    E. Segre

    2008-03-01

    Full Text Available In this study, we measure the extinction efficiency at 532 nm of absorbing aerosol particles coated with a non-absorbing solid and liquid organic shell with coating thickness varying between 5 and 100 nm using cavity ring down aerosol spectrometry. For this purpose, we use nigrosin, an organic black dye, as a model absorbing core and two non-absorbing organic substances as shells, glutaric acid (GA and Di-Ethyl-Hexyl-Sebacate (DEHS. The measured behavior of the coated particles is consistent with Mie calculations of core-shell particles. Errors between measured and calculated values for nigrosin coated with GA and DEHS are between 0.5% and 10.5% and between 0.5% and 9%, respectively. However, it is evident that the calculations are in better agreement with the measured results for thinner coatings. Possible reasons for these discrepancies are discussed.

  2. Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

    Directory of Open Access Journals (Sweden)

    A. A. Riziq

    2007-12-01

    Full Text Available In this study, we measure the extinction efficiency at 532 nm of absorbing aerosol particles coated with a non-absorbing solid and liquid organic shell with coating thickness varying between 5 and 100 nm using cavity ring down aerosol spectrometry. For this purpose, we use nigrosin, an organic black dye, as a model absorbing core and two non–absorbing organic substances as shells, glutaric acid (GA and Di-Ethyl-Hexyl-Sebacate (DEHS. The measured behavior of the coated particles is consistent with Mie calculations of core-shell particles. Errors between measured and calculated values for nigrosin coated with GA and DEHS are between 0.5% and 10.5% and between 0.5% and 9%, respectively. However, it is evident that the calculations are in better agreement with the measured results for thinner coatings. Possible reasons for these discrepancies are discussed.

  3. Codimension 2 and 3 situations in a ring cavity with elliptically polarized electromagnetic waves

    Science.gov (United States)

    Mártin, D. A.; Hoyuelos, M.

    2013-09-01

    We study pattern formation on the plane transverse to propagation direction, in a ring cavity filled with a Kerr-like medium, subject to an elliptically polarized incoming field, by means of two coupled Lugiato-Lefever equations. We consider a wide range of possible values for the coupling parameter between different polarizations, B¯, as may happen in composite materials. Positive and also negative refraction index materials are considered. Examples of marginal instability diagrams are shown. It is shown that, within the model, instabilities cannot be of codimension higher than 3. A method for finding parameters for which codimension 2 or 3 takes place is given. The method allows us to choose parameters for which unstable wavenumbers fulfill different relations. Numerical integration results where different instabilities coexist and compete are shown.

  4. Higher order test of Lorentz invariance with an optical ring cavity

    CERN Document Server

    Michimura, Yuta; Mewes, Matthew; Matsumoto, Nobuyuki; Ohmae, Noriaki; Kokuyama, Wataru; Aso, Yoichi; Ando, Masaki

    2016-01-01

    We have developed an apparatus to search for the higher-order Lorentz violation in photons by measuring the resonant frequency difference between two counterpropagating directions of an asymmetric optical ring cavity. From the year-long data taken between 2012 and 2013, we found no evidence for the light speed anisotropy at the level of $\\delta c/c \\lesssim 10^{-15}$. Limits on the dipole components of the anisotropy are improved by more than an order of magnitude, and limits on the hexapole components are obtained for the first time. An overview of our apparatus and the data analysis in the framework of the spherical harmonics decomposition of anisotropy are presented. We also present the status of the recent upgrade of the apparatus.

  5. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    CERN Document Server

    Karhu, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\

  6. Cavity ring-up spectroscopy for ultrafast sensing with optical microresonators

    CERN Document Server

    Rosenblum, Serge; Arazi, Lior; Vollmer, Frank; Dayan, Barak

    2015-01-01

    Spectroscopy of whispering-gallery mode (WGM) microresonators has become a powerful scientific tool, enabling detection of single viruses, nanoparticles, and even single molecules. Yet the demonstrated timescale of these schemes has been limited so far to milliseconds or more. Here we introduce a novel scheme that is orders of magnitude faster, capable of capturing complete spectral snapshots of WGM resonances at nanosecond timescales: cavity ring-up spectroscopy (CRUS). Based on sharply-rising detuned probe pulses, CRUS combines the sensitivity of heterodyne measurements with the highest possible, transform-limited acquisition rate. As a demonstration we capture spectra of microtoroid resonators at time intervals as short as 16 ns, directly monitoring sub-microsecond dynamics of their optomechanical vibrations, thermorefractive response and Kerr nonlinearity. CRUS holds promise for the study of fast biological processes such as enzyme kinetics, protein folding and light harvesting, with applications in other...

  7. Toward a real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy

    Directory of Open Access Journals (Sweden)

    X. Faïn

    2009-10-01

    Full Text Available A new sensor based on cavity ring-down spectroscopy (CRDS has been developed for the measurement of gaseous elemental mercury (Hg0 mass concentration with sub-ng m−3 detection limit and high temporal resolution. Cavity ring-down spectroscopy is a direct absorption technique that utilizes path lengths of up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. Our prototype uses a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg0 absorption line on a pulse to pulse basis to facilitate differential absorption measurements. Hg0 absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg0 concentrations determined by a Tekran 2537B analyzer over a Hg0 concentration range of four orders of magnitude, from 0.2 ng m−3 to 573 ng m−3 implying excellent linearity of both instruments. The current CRDS instrument has a~sensitivity of 0.10 ng m−3 at 10 s time resolution. This tool opens new prospects for the study of Hg0 because of its high temporal resolution and reduced limited sample volume requirements (<0.5 l of sample air. Future applications may include ambient Hg0 flux measurements with eddy covariance techniques, which require measurements of Hg0 concentrations with sub-ng m−3 sensitivity and sub-second time resolution.

  8. Operational management of progressing cavity pump; Gerenciamento do bombeio de cavidades progressivas

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Paulo Cesar Gasse de

    1999-12-01

    The main purpose of this work is to develop an intelligent system to management and control, that allows to periodically evaluate the operational performance of a petroleum field producing with the wells equipped with PCP - Progressing Cavity Pump. The work was developed in two main stages. Initially, it was accomplished a literature search about PCP, in order to identify its fundamental parameters that provide a better operation of the system. Afterwards, based on the experience obtained during the last years with the accompaniment of petroleum fields in Bahia, it is proposed a control system for management of the petroleum field operations, centered to PCP. This system uses techniques of artificial intelligence, as fuzzy sets, to obtain better interpolations. It is desired that the results presented in this Master's thesis can be useful to managers, engineers, supervisors and operators to obtain a continuous and optimized performance of this artificial lift method, at petroleum production. (author)

  9. A cavity ring-down spectroscopy sensor for real-time Hall thruster erosion measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B. C. [Physics Department, Colorado State University, Fort Collins, Colorado 80521 (United States); Huang, W. [NASA Glenn Research Center, 2100 Brookpark Rd., Cleveland, Ohio 44135 (United States); Tao, L.; Yamamoto, N.; Yalin, A. P., E-mail: ayalin@engr.colostate.edu [Mechanical Engineering Department, Colorado State University, Fort Collins, Colorado 80521 (United States); Gallimore, A. D. [Aerospace Engineering Department, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-05-15

    A continuous-wave cavity ring-down spectroscopy sensor for real-time measurements of sputtered boron from Hall thrusters has been developed. The sensor uses a continuous-wave frequency-quadrupled diode laser at 250 nm to probe ground state atomic boron sputtered from the boron nitride insulating channel. Validation results from a controlled setup using an ion beam and target showed good agreement with a simple finite-element model. Application of the sensor for measurements of two Hall thrusters, the H6 and SPT-70, is described. The H6 was tested at power levels ranging from 1.5 to 10 kW. Peak boron densities of 10 ± 2 × 10{sup 14} m{sup −3} were measured in the thruster plume, and the estimated eroded channel volume agreed within a factor of 2 of profilometry. The SPT-70 was tested at 600 and 660 W, yielding peak boron densities of 7.2 ± 1.1 × 10{sup 14} m{sup −3}, and the estimated erosion rate agreed within ∼20% of profilometry. Technical challenges associated with operating a high-finesse cavity in the presence of energetic plasma are also discussed.

  10. Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

    Directory of Open Access Journals (Sweden)

    C. L. Hagen

    2013-08-01

    Full Text Available A laser-based cavity ring-down spectroscopy (CRDS sensor for measurement of hydrogen chloride (HCl has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ limit of detection of < 20 pptv in 1 min and has high specificity to HCl. The measurement response time to changes in input HCl concentration is < 15 s. Validation studies with a previously calibrated permeation tube setup show an accuracy of better than 10%. The CRDS sensor was preliminarily tested in the field with two other HCl instruments (mist chamber and chemical ionization mass spectrometry, all of which were in broad agreement. The mist chamber and CRDS sensors both showed a 400 pptv plume within 50 pptv agreement. The sensor also allows simultaneous sensitive measurements of water and methane, and minimal hardware modification would allow detection of other near-infrared absorbers.

  11. Dynamic analysis of V-folded cavity for TEM00 operation of end-pumped solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Cunfa Li; Xiangchun Shi

    2005-01-01

    Based on graphic analysis design method of optical resonator, a simple design expression of V-folded cavity of end-pumped solid-state lasers with TEMoo operation is described, which satisfies two criterias of the resonator design. We give numerical simulation of spot size as a function of thermal focal length using this design approach whose advantages axe validated experimentally.

  12. Cavity ring-down study of the visible absorption spectrum of the phenyl radical and kinetics of its reactions with Cl, Br, Cl-2, and O-2

    DEFF Research Database (Denmark)

    Tonokura, K; Norikane, Y; Koshi, M;

    2002-01-01

    Cavity ring-down spectroscopy coupled with pulsed laser photolysis was used to study the visible absorption spectrum (490-535 nm, B-2(1)......Cavity ring-down spectroscopy coupled with pulsed laser photolysis was used to study the visible absorption spectrum (490-535 nm, B-2(1)...

  13. Precise and accurate d13C analysis of rock samples using Flash Combustion–Cavity Ring Down Laser Spectroscopy

    DEFF Research Database (Denmark)

    Balslev-Clausen, David Morten; Dahl, Tais Wittchen; Saad, Nabil

    2013-01-01

    expert know-how. Here, we measure 13C/12C in natural sedimentary samples using Combustion Module - Cavity Ring Down Spectroscopy (CM-CRDS) with average precision and standard reproducibility of 0.05‰ and 0.2‰ (1 s.d., n = 17), respectively. The accuracy of the technique was determined from certified...

  14. Novel use of cavity ring-down spectroscopy to investigate aquatic carbon cycling from microbial to ecosystem scales

    NARCIS (Netherlands)

    Maher, D.T.; Santos, I.S.; Leuven, J.R.F.W.; Oakes, J.M.; Erler, D.V.; Carvalho, M.C.; Eyre, B.D.

    2013-01-01

    Development of cavity ring-down spectroscopy (CRDS) has enabled real-time monitoring of carbon stable isotope ratios of carbon dioxide and methane in air. Here we demonstrate that CRDS can be adapted to assess aquatic carbon cycling processes from microbial to ecosystem scales. We first measured in

  15. Mid-infrared continuous wave cavity ring down spectroscopy of molecular ions using an optical parametric oscillator

    NARCIS (Netherlands)

    Verbraak, H.; Ngai, A.K.Y.; Persijn, S.T.; Harren, F.J.M.; Linnartz, H.

    2007-01-01

    A sensitive infrared detection scheme is presented in which continuous wave cavity ring down spectroscopy is used to record rovibrational spectra of molecular ions in direct absorption through supersonically expanding planar plasma. A cw optical parametric oscillator is used as a light source and

  16. A new approach to sum frequency generation of single-frequency blue light in a coupled ring cavity

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Petersen, Paul Michael

    2014-01-01

    We present a generic approach for the generation of tunable single-frequency light and demonstrate generation of more than 300 mW tunable light around 460 nm. One tapered diode laser is operated in a coupled ring cavity containing the nonlinear crystal and another tapered diode laser is sent...

  17. Liquid ring vacuum pumps, compressors and systems conventional and hermetic design

    CERN Document Server

    Bannwarth, Helmut

    2006-01-01

    Based on the very successful German editions, this English version has been thoroughly updated and revised to reflect the developments of the last years and the latest innovations in the field.Throughout, the author makes excellent use of real-life examples and highly praised didactics to disseminate his expert knowledge needed by vacuum technology users and engineers in their daily work at industrial plants, as consultants or in design offices. He covers in detail the most modern liquid ring pumps, with chapters dedicated to maintenance, explosion prevention and general procedures for saf

  18. Refractive index sensing using a multimode interference-based fiber sensor in a cavity ring-down system

    Science.gov (United States)

    Silva, Susana; Frazão, Orlando

    2017-04-01

    This work presents a multimode interference-based fiber sensor in a cavity ring-down system for sensing temperature-induced refractive index (RI) changes of water. The sensing head is based in multimodal interference (MMI) and it was placed inside the fiber loop cavity of the CRD system. A modulated laser source was used to send pulses down into the fiber loop cavity and an erbium-doped fiber amplifier (EDFA) was placed in the fiber ring to provide an observable signal with a reasonable decay time. The behavior of the sensing head to temperature was studied due to its intrinsic sensitivity to said parameter - a sensitivity of -1.6×10-9 μs/°C was attained. This allowed eliminating the temperature component from RI measurement of water and a linear sensitivity of 580 μs/RIU in the RI range of 1.324-1.331 was obtained.

  19. A modeling of pump impeller shroud and wear-ring seal as a whole, and its application to the pump rotordynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Tae Woong [Kyungwon Univ., Sungnam (Korea, Republic of); Lee, An Sung [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of)

    1998-06-01

    A modeling methodology of pump impeller shroud and wear-ring seal as a whole has been developed to give its rotordynamic coefficients. In this work the governing equations are derived for the continuous flow path of the impeller shroud and wear-ring seal. Pressure loss at the discontinuity of the connecting point between the impeller shroud and the wear-ring seal is defined by utilizing a pressure loss coefficient obtained from experimental measurements. The governing equations are solved directly by using the known conditions at the inlet of the impeller shroud and outlet of the wear-ring seal. A detailed rotordynamic analysis has been carried out on a 750 m-head fourteen-stage centrifugal pump system with the effects of the hydrodynamic forces of such as impeller shroud and wear-ring seals, balance piston, and interstage seals. Results have shown that the first critical speed obtained with all the seal effects is much higher than that obtained without those effects, and moreover that the system under consideration is unstable. Large cross coupled stiffness(k) of the impeller shroud and wear-ring seal has been suspected as the source of the problem. Design modifications of the impeller shroud and wear-ring seal geometry have been performed to decrease k and increase the direct damping(C). Finally, the design modifications have yielded a stable and well damped system.

  20. Generation of hyper-entanglement on polarization and energy-time based on a silicon micro-ring cavity.

    Science.gov (United States)

    Suo, Jing; Dong, Shuai; Zhang, Wei; Huang, Yidong; Peng, Jiangde

    2015-02-23

    In this paper, hyper-entanglement on polarization and energy-time is generated based on a silicon micro-ring cavity. The silicon micro-ring cavity is placed in a fiber loop connected by a polarization beam splitter. Photon pairs are generated by the spontaneous four wave mixing (SFWM) in the cavity bi-directionally. The two photon states of photon pairs propagate along the two directions of the fiber loop and are superposed in the polarization beam splitter with orthogonal polarizations, leading to the polarization entanglement generation. On the other hand, the energy-time entanglement is an intrinsic property of photon pairs generated by the SFWM, which maintains in the process of the state superposition. The property of polarization entanglement is demonstrated by the two photon interferences under two non-orthogonal polarization bases. The property of energy-time entanglement is demonstrated by the Franson type interference under two non-orthogonal phase bases. The raw visibilities of all the measured interference fringes are higher than 1/2, the bench mark for violation of the Bell inequality. It indicates that silicon micro-ring cavity is a promising candidate to realize high performance hyper-entanglement generation.

  1. RF cavity R&D at LBNL for the NLC Damping Rings,FY2000/2001

    Energy Technology Data Exchange (ETDEWEB)

    Rimmer, R.A.; Atkinson, D.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.; Weidenbach, W.

    2001-06-01

    This report contains a summary of the R&D activities at LBNL on RF cavities for the NLC damping rings during fiscal years 2000/2001. This work is a continuation of the NLC RF system R&D of the previous year [1]. These activities include the further optimization and fine tuning of the RF cavity design for both efficiency and damping of higher-order modes (HOMs). The cavity wall surface heating and stresses were reduced at the same time as the HOM damping was improved over previous designs. Final frequency tuning was performed using the high frequency electromagnetic analysis capability in ANSYS. The mechanical design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. The cavity ancillary components including the RF window, coupling box, HOM loads, and tuners have been studied in more detail. Other cavity options are discussed which might be desirable to either further lower the HOM impedance or increase the stored energy for reduced transient response. Superconducting designs and the use of external ''energy storage'' cavities are discussed. A section is included in which the calculation method is summarized and its accuracy assessed by comparisons with the laboratory measurements of the PEP-II cavity, including errors, and with the beam-sampled spectrum.

  2. Recommissioning of Duke Storage Ring with a HOM-Damped RF Cavity and a New Straight Section Lattice for FELs

    CERN Document Server

    Wu, Y K; Emamian, Mark; Faircloth, Joe; Gustavsson, J; Hartman, Steven M; Howell, C; Johnson, M; Li, Jingyi; Mikhailov, Stepan; Oakeley, Owen; Patterson, J; Pentico, Maurice; Popov, Victor; Rathbone, V; Swift, Gary; Wallace, Patrick W; Wang, Ping

    2005-01-01

    The Duke FEL lab operates a unique UV/VUV storage ring FEL and an FEL driven, nearly monochromatic, highly polarized, high intensity Compton gamma-ray source. The Duke storage ring light source is undergoing several phases of upgrade in order to significantly improve light source capabilities and performance. The 2004 phase included an upgrade of the RF system with a high-order mode damped RF cavity and a new 34 meter long straight section lattice to host new FEL wigglers in the next phase. This upgrade was completed in August 2004 and storage ring and light source commissioning were completed in November 2004. This paper will provide an overview of this upgrade project and report our commissioning experience of the storage ring and light sources.

  3. Radiocarbon Dioxide detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

    CERN Document Server

    Genoud, Guillaume; Phillips, Hilary; Dean, Julian; Merimaa, Mikko

    2015-01-01

    Monitoring of radiocarbon ($^{14}$C) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardised sample containing elevated levels of radiocarbon. Radiocarbon dioxide could be detected from samples with an isotopic ratio $^{14}$C/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m$^3$ in pure CO$_2$, or 2 Bq/m$^3$ in air after extraction of the CO$_2$ from an air sample. The instrument is simple, compact and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring of radioactive gaseous emissions in nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.

  4. Application of cavity ring-down spectroscopy to the Boltzmann constant determination.

    Science.gov (United States)

    Sun, Y R; Pan, H; Cheng, C-F; Liu, A-W; Zhang, J-T; Hu, S-M

    2011-10-10

    The Boltzmann constant can be optically determined by measuring the Doppler width of an absorption line of molecules at gas phase. We propose to apply a near infrared cavity ring-down (CRD) spectrometer for this purpose. The superior sensitivity of CRD spectroscopy and the good performance of the near-ir lasers can provide ppm (part-per-million) accuracy which will be competitive to present most accurate result obtained from the speed of sound in argon measurement. The possible influence to the uncertainty of the determined Doppler width from different causes are investigated, which includes the signal-to-noise level, laser frequency stability, detecting nonlinearity, and pressure broadening effect. The analysis shows that the CRD spectroscopy has some remarkable advantages over the direct absorption method proposed before. The design of the experimental setup is presented and the measurement of C2H2 line near 0.8 μm at room temperature has been carried out as a test of the instrument.

  5. Efficient and long-lived quantum memory with cold atoms inside a ring cavity

    CERN Document Server

    Bao, Xiao-Hui; Dietrich, Peter; Rui, Jun; Dück, Alexander; Strassel, Thorsten; Li, Li; Liu, Nai-Le; Zhao, Bo; Pan, Jian-Wei; 10.1038/nphys2324

    2012-01-01

    Quantum memories are regarded as one of the fundamental building blocks of linear-optical quantum computation and long-distance quantum communication. A long standing goal to realize scalable quantum information processing is to build a long-lived and efficient quantum memory. There have been significant efforts distributed towards this goal. However, either efficient but short-lived or long-lived but inefficient quantum memories have been demonstrated so far. Here we report a high-performance quantum memory in which long lifetime and high retrieval efficiency meet for the first time. By placing a ring cavity around an atomic ensemble, employing a pair of clock states, creating a long-wavelength spin wave, and arranging the setup in the gravitational direction, we realize a quantum memory with an intrinsic spin wave to photon conversion efficiency of 73(2)% together with a storage lifetime of 3.2(1) ms. This realization provides an essential tool towards scalable linear-optical quantum information processing.

  6. Detection of in vitro S-Nitrosylated Compounds with Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Rad, Mary Lynn; Mezher, Monique Michele; Gaston, Benjamin M.; Lehmann, Kevin

    2016-06-01

    Nitric oxide has been of strong biological interest for nearly 40 years due to its role in cardiovascular and nervous signaling. It has been shown that S-nitrosocompounds are the main carrier molecule for nitric oxide in biological systems. These compounds are also of interest due to their relationship to several diseases including muscular dystrophy, stroke, myocardial infarction, Alzheimer's disease, Parkinson's disease, cystic fibrosis, asthma, and pulmonary arterial hypertension. Understanding the role of these S-nitrosocompounds in these diseases requires concentration studies in healthy and diseased tissues as well as metabolic studies using isotopically labeled S-nitroso precursors such at 15N-arginine. The current widely used techniques for these studies include chemiluminescence, which is blind to isotopic substitution, and mass spectrometry, which is known to artificially create and break S-NO bonds in the sample preparation stages. To this end we have designed and constructed a mid-IR cavity ring-down spectrometer for the detection of nitric oxide released from the target S-nitrosocompounds. Progress toward measuring S-NO groups in biological samples using the CRDS instrument will be presented.

  7. Stable isotope analysis of saline water samples on a cavity ring-down spectroscopy instrument.

    Science.gov (United States)

    Skrzypek, Grzegorz; Ford, Douglas

    2014-01-01

    The analysis of the stable hydrogen and oxygen isotope composition of water using cavity ring-down spectroscopy (CRDS) instruments utilizing infrared absorption spectroscopy have been comprehensively tested. However, potential limitations of infrared spectroscopy for the analysis of highly saline water have not yet been evaluated. In this study, we assessed uncertainty arising from elevated salt concentrations in water analyzed on a CRDS instrument and the necessity of a correction procedure. We prepared various solutions of mixed salts and separate solutions with individual salts (NaCl, KCl, MgCl2, and CaCl2) using deionized water with a known stable isotope composition. Most of the individual salt and salt mixture solutions (some up to 340 g L(-1)) had δ-values within the range usual for CRDS analytical uncertainty (0.1‰ for δ (18)O and 1.0‰ for δ (2)H). Results were not compromised even when the total load of salt in the vaporizer reached ∼38.5 mg (equivalent to build up after running ∼100 ocean water samples). Therefore, highly saline mixtures can be successfully analyzed using CRDS, except highly concentrated MgCl2 solutions, without the need for an additional correction if the vaporizer is frequently cleaned and MgCl2 concentration in water is relatively low.

  8. Positive displacement rotary pump

    Science.gov (United States)

    Moody, Paul E.

    1994-04-01

    An eccentric drive rotates inside a ring that is hinged to a plate and an elastomeric curtain is wrapped around the ring and across an articulated plate. The curtain moves along a cylindrical wall inside the pump cavity to move fluid from an inlet to an outlet end of the chamber. Two or more chambers can be coupled in series or in parallel with one another.

  9. Single photon emission and quantum ring-cavity coupling in InAs/GaAs quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, E; Nowak, A K; Sanvitto, D; Meulen, H P van der; Calleja, J M [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); MartInez, L J; Prieto, I; Alija, A R; Granados, D; Taboada, A G; GarcIa, J M; Postigo, P A [Instituto de Microelectronica de Madrid, Centro Nacional de MicrotecnologIa, CSIC, Isaac Newton 8, PTM Tres Cantos, E-28760 Madrid (Spain); Sarkar, D, E-mail: eva.gallardo@uam.e [Department of Physics and Astronomy, University of Sheffield, S3 7RH (United Kingdom)

    2010-02-01

    Different InAs/GaAs quantum rings embedded in a photonic crystal microcavity are studied by quantum correlation measurements. Single photon emission, with g{sup (2)}(0) values around 0.3, is demonstrated for a quantum ring not coupled to the microcavity. Characteristic rise-times are found to be longer for excitons than for biexcitons, resulting in the time asymmetry of the exciton-biexciton cross-correlation. No antibunching is observed in another quantum ring weakly coupled to the microcavity.

  10. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    Science.gov (United States)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  11. Development of a cavity ring-down spectroscopy sensor for boron nitride sputter erosion in Hall thrusters

    CERN Document Server

    Tao, Lei; Gallimore, Alec D; Yalin, Azer P

    2010-01-01

    Sputter erosion of boron nitride (BN) is a critically important process in Hall thrusters from the point of view of both lifetime assessment and contamination effects. This contribution describes the development of a laser based sensor for in situ monitoring of sputtered BN from Hall thrusters. We present a continuous-wave cavity ring-down spectroscopy (cw-CRDS) system and its demonstrative measurement results from BN sputtering experiments.

  12. Cavity ring-down spectroscopy sensor development for high-time-resolution measurements of gaseous elemental mercury in ambient air

    OpenAIRE

    Pierce, A; D. Obrist; H. Moosmüller; X. Faïn; Moore, C.

    2013-01-01

    We describe further development of a previous laboratory prototype pulsed cavity ring-down spectroscopy (CRDS) sensor into a field-deployable system for high-time-resolution, continuous, and automated measurement of gaseous elemental mercury (GEM) concentrations in ambient air. We employed an external, isotopically enriched Hg cell for automated locking and stabilization of the laser wavelength on the GEM peak absorption during measurements. Further, we describe implementation of differential...

  13. Single Brillouin frequency shifted S-band multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier in ring cavity

    Science.gov (United States)

    Reshak, A. H.; Hambali, N. A. M. Ahmad; Shahimin, M. M.; Wahid, M. H. A.; Anwar, Nur Elina; Alahmed, Zeyad A.; Chyský, J.

    2016-10-01

    This paper is focusing on simulation and analyzing of S-band multi-wavelength Brillouin-Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity. Raman amplifier-average power model is employed for signal amplification. This laser system is operates in S-band wavelength region due to vast demanding on transmitting the information. Multi-wavelength fiber lasers based on hybrid Brillouin-Raman gain configuration supported by Raman scattering effect have attracted significant research interest due to its ability to produced multi-wavelength signals from a single light source. In multi-wavelength Brillouin-Raman fiber, single mode fiber is utilized as the nonlinear gain medium. From output results, 90% output coupling ratio has ability to provide the maximum average output power of 43 dBm at Brillouin pump power of 20 dBm and Raman pump power of 14 dBm. Furthermore, multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier is capable of generated 7 Brillouin Stokes signals at 1480 nm, 1510 nm and 1530 nm.

  14. Silver nanoparticle-film based saturable absorber for passively Q-switched erbium-doped fiber laser (EDFL) in ring cavity configuration

    Science.gov (United States)

    Ahmad, H.; Ruslan, N. E.; Ismail, M. A.; Ali, Z. A.; Reduan, S. A.; Lee, C. S. J.; Harun, S. W.

    2016-09-01

    We report a passive Q-switched erbium-doped fiber laser based on silver (Ag) nanoparticle thin-film saturable absorber (SA). The thin film was sandwiched between two fiber ferrules, which offer flexibility and easy integration into the ring cavity. Self-started and stable Q-switching is achieved at a central wavelength of 1558.7 nm within the C-band region. The repetition rate and pulse duration shows a typical Q-switched laser profile as we increase the pump power; the repetition rate increases from 19.471-74.074 kHz while pulse duration decreases from 8.88-3.2 µs. A signal-to-noise ratio value of 35 dB was obtained at 100 mW pump power. By using a balanced twin-detector method, the modulation depth and saturation intensity of the Ag nanoparticle thin film were measured to be 31.6% and 0.54 MW cm-2 respectively. This result offers another alternative to the existing SA materials.

  15. Cavities

    Science.gov (United States)

    ... may pass these bacteria to a child through kissing, sampling the child's food, or sharing eating utensils. ... pass decay-causing bacteria to their children through kissing or sharing eating utensils. Symptoms of Cavities Whether ...

  16. Numerical Analysis of Rotating Pumping Flows in Inter-Coil Rotor Cavities and Short Cooling Grooves of a Generator

    Directory of Open Access Journals (Sweden)

    Wei Tong

    2001-01-01

    Full Text Available An important characteristic of wall rotating-driven flows is the tendency of fluid with high angular momentum to be flung radially outward. For a generator, the rotor rotating-driven flow, usually referred to as the rotating pumping flow, plays an important role in rotor winding cooling. In this study, three-dimensional numerical analyzes are presented for turbulent pumping flow in the inter-coil rotor cavity and short cooling grooves of a generator. Calculations of the flow field and the mass flux distribution through the grooves were carried out in a sequence of four related cases Under an isothermal condition: (a pumping flow, which is the self-generated flow resulted from the rotor pumping action; (b mixing flow, which is the combination of the ventilating flow and pumping flow, under a constant density condition; (c mixing flow, with density modeled by the ideal gas law; and (d mixing flow, with different pressure differentials applied on the system. The comparisons of the results from these cases can provide useful information regarding the impacts of the ventilating flow, gas density, and system pressure differential on the mass flux distribution in the short cooling grooves. Results show that the pumping effect is strong enough to generate the cooling flow for rotor winding cooling. Therefore, for small- or mid-size generators ventilation fans may be eliminated. It also suggests that increasing the chimney dimension can improve the distribution uniformity of mass flux through the cooling grooves.

  17. Quantifying Fugitive Methane Emissions at an Underground Coal Fire Using Cavity Ring-Down Spectroscopy Technology

    Science.gov (United States)

    Fleck, D.; Gannon, L.; Kim-Hak, D.; Ide, T.

    2016-12-01

    Understanding methane emissions is of utmost importance due to its greenhouse warming potential. Methane emissions can occur from a variety of natural and anthropogenic sources which include wetlands, landfills, oil/gas/coal extraction activities, underground coal fires, and natural gas distribution systems. Locating and containing these emissions are critical to minimizing their environmental impacts and economically beneficial when retrieving large fugitive amounts. In order to design a way to mitigate these methane emissions, they must first be accurately quantified. One such quantification method is to measure methane fluxes, which is a measurement technique that is calculated based on rate of gas accumulation in a known chamber volume over methane seepages. This allows for quantification of greenhouse gas emissions at a localized level (sub one meter) that can complement remote sensing and other largescale modeling techniques to further paint the picture of emission points. High performance analyzers are required to provide both sufficient temporal resolution and precise concentration measurements in order to make these measurements over only minutes. A method of measuring methane fluxes was developed using the latest portable, battery-powered Cavity Ring-Down Spectroscopy analyzer from Picarro (G4301). In combination with a mobile accumulation chamber, the instrument allows for rapid measurement of methane and carbon dioxide fluxes over wide areas. For this study, methane fluxes that were measured at an underground coal fire near the Four Corners region using the Picarro analyzer are presented. The flux rates collected demonstrate the ability for the analyzer to detect methane fluxes across many orders of magnitude. Measurements were accompanied by simultaneously geotagging the measurements with GPS to georeferenced the data. Methane flux data were instrumental in our ability to characterize the extent and the migration of the underground fire. In the future

  18. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    Science.gov (United States)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsälä, M.; Hoekstra, S.; Halonen, L.

    2016-06-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν4 1 + ν5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) × 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.

  19. Conversion of a Continuous Flow Cavity Ring-Down Spectrometer to Measure 13C in CO2 Using Static Analyses of Small Volume Grab Samples (Invited)

    Science.gov (United States)

    Rahn, T.; Jordanova, K.; Berryman, E.; van Pelt, A. D.; Marshall, J. D.

    2010-12-01

    Laser-based analyses of concentration and isotopic content allow unprecedented temporal resolution for a number of important atmospheric constituents. Perhaps overlooked is the potential for these tools to also provide analyses in a more traditional "mass spectrometric" mode that is readily deployable in a field setting. Certain sampling regimes (e.g. soil profiles) are not appropriate for continuous sampling due to their slow change and disturbance of gradients caused by frequent/continuous sampling. We have modified the inlet and plumbing system of a commercial continuous flow cavity ring-down spectrometer in a manner that allows for 13C analyses of CO2 from syringe samples at volumes as small as 25 ml of air with ambient concentrations of CO2. The method employs an external high vacuum pump and a series of programmable micro-valves that allow for evacuation of the long-pass ring-down cell followed by controlled filling, via syringe, of the cavity to optimal sampling pressure and subsequent static analysis of CO2 concentration and 13C /13C ratios. The set-up is field deployable with modest power requirements and allows for near real time analysis in a variety of sampling environments and on-the-fly determination of sampling protocol. In its current configuration, the system provides precision of 1% for CO2 concentration and 0.3 permil for δ13C in replicate analyses of reference air. We have deployed the system to a field laboratory in central New Mexico near a controlled tree mortality research site where post-mortality ecosystem CO2 evolution is being studied. Results from the first field season will be presented and discussed.

  20. Near Infrared Cavity Ring-Down Spectroscopy for Isotopic Analyses of CH4 on Future Martian Surface Missions

    Science.gov (United States)

    Chen, Y.; Mahaffy P.; Holmes, V.; Burris, J.; Morey, P.; Lehmann, K.K.; Lollar, B. Sherwood; Lacrampe-Couloume, G.; Onstott, T.C.

    2014-01-01

    A compact Near Infrared Continuous Wave Cavity Ring-Down Spectrometer (near-IR-cw-CRDS) was developed as a candidate for future planetary surface missions. The optical cavity was made of titanium with rugged quartz windows to protect the delicate super cavity from the harsh environmental changes that it would experience during space flight and a Martian surface mission. This design assured the long-term stability of the system. The system applied three distributed feedback laser diodes (DFB-LD), two of which were tuned to the absorption line peaks of (sup 12)CH4 and (sup 13)CH4 at 6046.954 inverse centimeters and 6049.121 inverse centimeters, respectively. The third laser was tuned to a spectral-lines-free region for measuring the baseline cavity loss. The multiple laser design compensated for typical baseline drift of a CRDS system and, thus, improved the overall precision. A semiconductor optical amplifier (SOA) was used instead of an Acousto-Optic Module (AOM) to initiate the cavity ring-down events. It maintained high acquisition rates such as AOM, but consumed less power. High data acquisition rates combined with improved long-term stability yielded precise isotopic measurements in this near-IR region even though the strongest CH4 absorption line in this region is 140 times weaker than that of the strongest mid-IR absorption band. The current system has a detection limit of 1.4 times 10( sup –12) inverse centimeters for (sup 13)CH4. This limit corresponds to approximately 7 parts per trillion volume of CH4 at 100 Torrs. With no further improvements the detection limit of our current near IR-cw-CRDS at an ambient Martian pressure of approximately 6 Torrs (8 millibars) would be 0.25 parts per billion volume for one 3.3 minute long analysis.

  1. Multimode interference-based fiber sensor in a cavity ring-down system for refractive index measurement

    Science.gov (United States)

    Silva, Susana; Frazão, Orlando

    2017-06-01

    This work reports a multimode interference-based fiber sensor in a cavity ring-down system (CRD) for sensing temperature-induced refractive index (RI) changes of water. The sensing head is based in multimodal interference (MMI) and it is placed inside the fiber loop cavity of the CRD system. A modulated laser source was used to send pulses down into the fiber loop cavity and an erbium-doped fiber amplifier (EDFA) was placed in the fiber ring to provide an observable signal with a reasonable decay time. The behavior of the sensing head to temperature was studied due to its intrinsic sensitivity to said parameter - a sensitivity of -1.6×10-9 μs/°C was attained. This allowed eliminating the temperature component from RI measurement of water and a linear sensitivity of 580 μs/RIU in the RI range of 1.324-1.331 was obtained. The use of a MMI fiber sensor in the proposed CRD configuration allowed achieving a sensitivity ∼4-fold than that obtained with a tilted fiber Bragg grating and ∼2-fold than that when a micrometric channel inscribed in the fiber was used.

  2. Toward real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy

    Directory of Open Access Journals (Sweden)

    X. Faïn

    2010-03-01

    Full Text Available Cavity ring-down spectroscopy (CRDS is a direct absorption technique that utilizes path lengths up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. This tool opens new prospects for study of gaseous elemental mercury (Hg0 because of its high temporal resolution and reduced sample volume requirements (<0.5 l of sample air. We developed a new sensor based on CRDS for measurement of (Hg0 mass concentration. Sensor characteristics include sub-ng m−3 detection limit and high temporal resolution using a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg0 absorption line on a pulse-to-pulse basis to facilitate differential absorption measurements. Hg0 absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg0 concentrations determined by a Tekran 2537B analyzer over an Hg0 concentration range from 0.2 ng m−3 to 573 ng m−3, implying excellent linearity of both instruments. The current CRDS instrument has a sensitivity of 0.10 ng Hg0 m−3 at 10-s time resolution. Ambient-air tests showed that background Hg0 levels can be detected at low temporal resolution (i.e., 1 s, but also highlight a need for high-frequency (i.e., pulse-to-pulse differential on/off-line tuning of the laser wavelength to account for instabilities of the CRDS system and variable background absorption interferences. Future applications may include ambient Hg0 flux measurements with eddy covariance techniques, which require measurements of Hg0 concentrations with sub-ng m−3 sensitivity and sub-second time

  3. Diode-pumped low noise CW 355-nm intra-cavity tripled laser up to 20 mW

    Science.gov (United States)

    Aubert, Nicolas; Georges, Thierry; Chauzat, Corinne; Le Bras, Raymond; Féron, Patrice

    2006-04-01

    Low noise lasers in the UV spectrum (355 nm) are important for many applications like spectroscopy, confocal microscopy, flow cytometry, cell sorting, CD mastering, semiconductor inspection and reprographics. The UV CW laser sources currently commercially available, are restricted to excimers lasers, gas ions lasers which suffer from low power efficiency (0.01% or less), high electrical consumption and bulky dimensions. These products, which are expensive, are still waiting for practical replacements. To our best knowledge, we report in this paper the first efficient low noise diode-pumped neodymium doped solid-state laser operating at 355 nm by intra-cavity third harmonic generation (THG). The fundamental infrared laser light is generated by a diode-pumped Nd:YVO 4 crystal optically contacted with others components of the laser cavity. Intra-cavity SHG and THG are achieved with a KTP and LBO respectively. Several configurations have led to low noise 355 nm single-frequency operation at a power exceeding 10 mW. We believe that this power can still be improved.

  4. The use of nonlinear dynamics of erbium-doped fiber laser at pump modulation for intra-cavity sensing

    Science.gov (United States)

    Arellano-Sotelo, H.; Kir'yanov, A. V.; Barmenkov, Yu. O.; Aboites, V.

    2011-02-01

    We report the use of nonlinear dynamics of an erbium-doped fiber laser (EDFL) at pump modulation, namely the period-1 pulsed regime, for intra-cavity loss sensing and demonstrate noticeable sensitivity enhancement of an EDFL-based sensor, provided by this arrangement. Experimentally, we obtain a ten-fold increase of the sensor response, i.e. peak-to-peak pulse amplitude against loss variation, as compared with the standard sensing schemes using a low-power wide-spectrum light emitting diode (LED) or fiber laser without external modulation. This advantage originates from a strong dependence of pulse amplitude in the period-1 regime on intra-cavity loss variable that is, in turn, determined by the interrelation of relaxation frequency (an internal EDFL parameter) and frequency and depth of external (pump) modulation. A modeling of the EDFL-based sensor, presented for the case when the laser operates in the period-1 regime, allows an insight into the sensor operation details and opens the gate to its further optimization. The proposed sensing method seems to be a proper choice for the applications where an intra-cavity sensor's head has high internal loss (≥10 dB) while sensed loss is varied within a quite narrow range (a few dB).

  5. 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...

  6. 1.34μm Nd:YVO4 high efficiency laser end-pumped by diode-laser of flat-concave cavity type

    Institute of Scientific and Technical Information of China (English)

    Shang Lian-Ju; Ning Ji-Ping

    2005-01-01

    The parameters of 1.34μm Nd:YVO4 laser end-pumped with flat-concave cavity are theoretically analysed. The analysis in this paper may be helpful to the designing of kindred lasers. The operation of 1.34μm Nd:YVO4 laser end-pumped by a diode-laser with flat-concave cavity is achieved. The output power of 3.51W at 1.34μm and optical to optical conversion efficiency of 39.0% are obtained at the pump power of 9.0W.

  7. Technical brief: Pump-probe paradigm in an integrating cavity to study photodecomposition processes.

    Science.gov (United States)

    Gonzalez-Fernandez, Federico; Betts-Obregon, Brandi; Tsin, Andrew T; DeSa, Richard J

    2016-01-01

    flashes to be placed between scans. Exposure of the all-trans retinol to 366 nm flashes resulted in marked reduction in absorbance and a blue shift of the λmax. A white LED, despite its higher photon output, did not support all-trans retinol photolysis. Singular value decomposition (SVD) analysis revealed three spectral intermediates with mechanism, I -> II -> III. HPLC analysis of the reactants at the beginning and the conclusion of the light exposure confirmed the retinol photodecomposition. The highly reflecting cavity acts as a multipass cuvette that markedly increased the light path length and, thus, sensitivity. Triggering the LED during a dark period within the scan time allowed the actinic flashes to be interleafed between scans in a pump-probe paradigm. Furthermore, the entire sample was exposed to scan beam and actinic flashes, which is not possible in traditional spectrophotometers. Finally, the integrating cavity cuvette allowed use of turbid samples. SVD was useful for resolving spectral intermediates. Although the identity of the intermediates was not determined here, the ability to define molecular intermediates during photodecomposition reactions will allow future studies to isolate and identify the degradation products and determine the mechanism of light-induced retinoid degradation and that of retinoid-binding protein-mediated photoprotection.

  8. Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

    Science.gov (United States)

    Gao, Weiwei; Wang, Lin; Li, Heting

    2017-03-01

    In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

  9. Cavity Ring Down Absorption of O2 in Air as a Temperature Sensor for an Open and a Cryogenic Optical Cavity.

    Science.gov (United States)

    Nyaupane, Parashu R; Perez-Delgado, Yasnahir; Camejo, David; Wright, Lesley M; Manzanares, Carlos E

    2016-06-30

    The A-band of oxygen has been measured at low resolution at temperatures between 90 K and 373 K using the phase shift cavity ring down (PS-CRD) technique. For temperatures between 90 K and 295 K, the PS-CRD technique presented here involves an optical cavity attached to a cryostat. The static cell and mirrors of the optical cavity are all inside a vacuum chamber at the same temperature of the cryostat. The temperature of the cell can be changed between 77 K and 295 K. For temperatures above 295 K, a hollow glass cylindrical tube without windows has been inserted inside an optical cavity to measure the temperature of air flowing through the tube. The cavity consists of two highly reflective mirrors which are mounted parallel to each other and separated by a distance of 93 cm. In this experiment, air is passed through a heated tube. The temperature of the air flowing through the tube is determined by measuring the intensity of the oxygen absorption as a function of the wavenumber. The A-band of oxygen is measured between 298 K and 373 K, with several air flow rates. To obtain the temperature, the energy of the lower rotational state for seven selected rotational transitions is linearly fitted to a logarithmic function that contains the relative intensity of the rotational transition, the initial and final rotational quantum numbers, and the energy of the transition. Accuracy of the temperature measurement is determined by comparing the calculated temperature from the spectra with the temperature obtained from a calibrated thermocouple inserted at the center of the tube. This flowing air temperature sensor will be used to measure the temperatures of cooling air at the input (cold air) and output (hot air) after cooling the blades of a laboratory gas turbine. The results could contribute to improvements in turbine blade cooling design.

  10. A Bidirectional, Diode-Pumped, Passively Mode-Locked Nd:YVO4 Ring Laser with a Low-Temperature-Grown Semiconductor Saturable Absorber Mirror

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-Qiang; YAO Jian-Quan; WANG Peng; WANG Yong-Gang; ZHANG Zhi-Gang

    2007-01-01

    We report the operation of a bidirectional picosecond pulsed ring Nd:YVO4 laser based on a low-temperaturegrown semiconductor saturable absorber mirror. Except for the laser crystal, the six-mirror ring laser cavity has no intra-cavity elements such as focusing lens or mirror. The bidirectional mode locked pluses are obtained at the repetition rate of 117.5MHz, pulse duration of Sips, power of 2×200 mW.

  11. CESAR, 2 MeV electron storage ring; construction period; RF cavity.

    CERN Multimedia

    Service Photo

    1962-01-01

    RF cavity. There were 2 identical ones: one for stacking (accumulation) procedures; the other for scanning with "empty buckets" (measurement of beam density distribution). Both were operated at h=2 (2nd harmonic of the revolution frequency), i.e. at around 24.4 MHz. Voltage, frequency and phase were programmed with analogue circuits.

  12. RF cavities of CESAR (2 MeV electron storage ring).

    CERN Multimedia

    Service Photo

    1968-01-01

    RF cavity. There were 2 identical ones: one for stacking (accumulation) procedures; the other for scanning with "empty buckets" (measurement of beam density distribution). Both were operated at h=2 (2nd harmonic of the revolution frequency), i.e. at around 24.4 MHz. Voltage, frequency and phase were programmed with analogue circuits.

  13. A Laser Feedback Control Design for Passive Ring Laser Gyros in a Very High Finesse Cavity.

    Science.gov (United States)

    1985-12-01

    14 II. Theory ....................... 16 Optical Cavities ................ 16 Laser Fundamentals ...............24 The Gaussian Beam. ...............28...c 1-(ABC 1h(.8 = (2.18) F = 1 2.19) - (RARCRD) t = = (2.20) C c[i- (RARRc%)] Laser Fundamentals A laser consists of three basic components: a gain

  14. Dependence of gain and phase-shift on crystal parameters and pump intensity in unidirectional photorefractive ring resonators

    Indian Academy of Sciences (India)

    M K Maurya; T K Yadav; R A Yadav

    2009-04-01

    The steady-state amplification of light beam during two-wave mixing in photorefractive materials has been analysed in the strong nonlinear regime. The oscillation conditions for unidirectional ring resonator have been studied. The signal beam can be amplified in the presence of material absorption, provided the gain due to the beam coupling is large enough to overcome the cavity losses. Such amplification is responsible for the oscillations. The gain bandwidth is only a few Hz. In spite of such an extremely narrow bandwidth, unidirectional oscillation can be observed easily at any cavity length in ring resonators by using photorefractive crystals as the medium and this can be explained in terms of the photorefractive phase-shift. The presence of such a phase-shift allows the possibility of the non-reciprocal steady-state transfer of energy between the two light beams. Dependence of gain bandwidth on coupling constant, absorption coefficient of the material's cavity length (crystal length) and modulation ratio have also been studied.

  15. Real-Tme Boron Nitride Erosion Measurements of the HiVHAc Thruster via Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Lee, Brian C.; Yalin, Azer P.; Gallimore, Alec; Huang, Wensheng; Kamhawi, Hani

    2013-01-01

    Cavity ring-down spectroscopy was used to make real-time erosion measurements from the NASA High Voltage Hall Accelerator thruster. The optical sensor uses 250 nm light to measure absorption of atomic boron in the plume of an operating Hall thruster. Theerosion rate of the High Voltage Hall Accelerator thruster was measured for discharge voltages ranging from 330 to 600 V and discharge powers ranging from 1 to 3 kW. Boron densities as high as 6.5 x 10(exp 15) per cubic meter were found within the channel. Using a very simple boronvelocity model, approximate volumetric erosion rates between 5.0 x 10(exp -12) and 8.2 x 10(exp -12) cubic meter per second were found.

  16. Linear and nonlinear resonance features of an erbium-doped fibre ring laser under cavity-loss modulation

    Indian Academy of Sciences (India)

    Aditi Ghosh; R Vijaya

    2014-07-01

    The continuous-wave output of a single-mode erbium-doped fibre ring laser when subjected to cavity-loss modulation is found to exhibit linear as well as nonlinear resonances. At sufficiently low driving amplitude, the system resembles a linear damped oscillator. At higher amplitudes, the dynamical study of these resonances shows that the behaviour of the system exhibits features of a nonlinear damped oscillator under harmonic modulation. These nonlinear dynamical features, including harmonic and subharmonic resonances, have been studied experimentally and analysed with the help of a simple time-domain and frequency-domain information obtained from the output of the laser. All the studies are restricted to the modulation frequency lying in a regime near the relaxation oscillation frequency.

  17. Surface-emitting circular DFB, disk-, and ring-Bragg resonator lasers with chirped gratings. II: nonuniform pumping and far-field patterns.

    Science.gov (United States)

    Sun, Xiankai; Yariv, Amnon

    2009-01-05

    This is a continuation of our previous work [Opt. Express 16, 9155 (2008)]. In this paper we investigate the effect of nonuniform pumping on the modal properties of surface-emitting chirped circular grating lasers. By numerically solving the coupled-mode equations and matching the boundaries we compare and discuss the threshold pump levels and frequency detuning factors for three pumping profiles: uniform, Gaussian, and annular. Depending on the overlap of the pumping and modal profiles, Gaussian pumping results in the lowest threshold pump levels except for the fundamental mode of ring Bragg resonator laser, and annular pumping provides larger threshold discrimination between the fundamental and first-order modes of circular DFB and ring Bragg resonator lasers, which is favorable for single-mode operation in these lasers. We also study the far-field patterns of the fundamental modes of circular DFB, disk-, and ring- Bragg resonator lasers. Circular DFB and ring Bragg resonator lasers have the first-order dominating peak, while disk Bragg resonator laser exhibits the zeroth-order dominating peak.

  18. Superconducting qubit in a nonstationary transmission line cavity: Parametric excitation, periodic pumping, and energy dissipation

    Science.gov (United States)

    Zhukov, A. A.; Shapiro, D. S.; Remizov, S. V.; Pogosov, W. V.; Lozovik, Yu. E.

    2017-02-01

    We consider a superconducting qubit coupled to the nonstationary transmission line cavity with modulated frequency taking into account energy dissipation. Previously, it was demonstrated that in the case of a single nonadiabatical modulation of a cavity frequency there are two channels of a two-level system excitation which are due to the absorption of Casimir photons and due to the counterrotating wave processes responsible for the dynamical Lamb effect. We show that the parametric periodical modulation of the resonator frequency can increase dramatically the excitation probability. Remarkably, counterrotating wave processes under such a modulation start to play an important role even in the resonant regime. Our predictions can be used to control qubit-resonator quantum states as well as to study experimentally different channels of a parametric qubit excitation.

  19. Nonlinear response of a unidirectional erbium-doped fiber ring laser to a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2002-11-01

    The response of a unidirectional erbium-doped fiber ring laser, excited by a sinusoidally modulated pump power, is analyzed both experimentally and theoretically. Experimentally, several resonance peaks are observed, as well as different frequency ranges showing bistable behaviour. Appearance of all resonance peaks obtained can be explained taking into account simple relations between the pump modulation frequency and the system natural frequency. Theoretically, it is shown how a model which combines the theory of erbium-doped fibers and the semiclassical laser treatment can account for all phenomena observed, with good agreement. In particular, it is demonstrated that a correct description of the bistable regions requires taking into account powers and population distributions along the laser active medium.

  20. Absorber and gain chip optimization to improve performance from a passively modelocked electrically pumped vertical external cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Zaugg, C. A., E-mail: zauggc@phys.ethz.ch; Mangold, M.; Pallmann, W. P.; Golling, M.; Tilma, B. W.; Keller, U. [Department of Physics, Institute for Quantum Electronics, ETH Zürich, 8093 Zürich (Switzerland); Gronenborn, S.; Moench, H.; Weichmann, U. [Philips Technologie GmbH Photonics Aachen, Steinbachstrasse 15, 52074 Aachen (Germany); Miller, M. [Philips Technologie GmbH U-L-M Photonics, Lise-Meitner-Strasse 13, 89081 Ulm (Germany)

    2014-03-24

    We present an electrically pumped vertical-external-cavity surface-emitting laser (EP-VECSEL) modelocked with a semiconductor saturable absorber mirror (SESAM) with significantly improved performance. In different cavity configurations, we present the shortest pulses (2.5 ps), highest average output power (53.2 mW), highest repetition rate (18.2 GHz), and highest peak power (4.7 W) to date. The simple and low-cost concept of EP-VECSELs is very attractive for mass-market applications such as optical communication and clocking. The improvements result from an optimized gain chip from Philips Technologie GmbH and a SESAM, specifically designed for EP-VECSELs. For the gain chip, we found a better trade-off between electrical and optical losses with an optimized doping scheme in the substrate to increase the average output power. Furthermore, the device's bottom contact diameter (60 μm) is smaller than the oxide aperture diameter (100 μm), which favors electro-optical conversion into a TEM{sub 00} mode. Compared to optically pumped VECSELs we have to increase the field enhancement in the active region of an EP-VECSEL which requires a SESAM with lower saturation fluence and higher modulation depth for modelocking. We therefore used a resonant quantum well SESAM with a 3.5-pair dielectric top-coating (SiN{sub x} and SiO{sub 2}) to enhance the field in the absorber at the lasing wavelength of 980 nm. The absorption bandedge at room temperature is detuned (965 nm) compared to the resonance (980 nm), which enables temperature-tuning of the modulation depth and saturation fluence from approximately 2.5% up to 15% and from 20 μJ/cm{sup 2} to 1.1 μJ/cm{sup 2}, respectively.

  1. Absorber and gain chip optimization to improve performance from a passively modelocked electrically pumped vertical external cavity surface emitting laser

    Science.gov (United States)

    Zaugg, C. A.; Gronenborn, S.; Moench, H.; Mangold, M.; Miller, M.; Weichmann, U.; Pallmann, W. P.; Golling, M.; Tilma, B. W.; Keller, U.

    2014-03-01

    We present an electrically pumped vertical-external-cavity surface-emitting laser (EP-VECSEL) modelocked with a semiconductor saturable absorber mirror (SESAM) with significantly improved performance. In different cavity configurations, we present the shortest pulses (2.5 ps), highest average output power (53.2 mW), highest repetition rate (18.2 GHz), and highest peak power (4.7 W) to date. The simple and low-cost concept of EP-VECSELs is very attractive for mass-market applications such as optical communication and clocking. The improvements result from an optimized gain chip from Philips Technologie GmbH and a SESAM, specifically designed for EP-VECSELs. For the gain chip, we found a better trade-off between electrical and optical losses with an optimized doping scheme in the substrate to increase the average output power. Furthermore, the device's bottom contact diameter (60 μm) is smaller than the oxide aperture diameter (100 μm), which favors electro-optical conversion into a TEM00 mode. Compared to optically pumped VECSELs we have to increase the field enhancement in the active region of an EP-VECSEL which requires a SESAM with lower saturation fluence and higher modulation depth for modelocking. We therefore used a resonant quantum well SESAM with a 3.5-pair dielectric top-coating (SiNx and SiO2) to enhance the field in the absorber at the lasing wavelength of 980 nm. The absorption bandedge at room temperature is detuned (965 nm) compared to the resonance (980 nm), which enables temperature-tuning of the modulation depth and saturation fluence from approximately 2.5% up to 15% and from 20 μJ/cm2 to 1.1 μJ/cm2, respectively.

  2. Diode laser cavity ring-down spectroscopy for in situ measurement of NO3 radical in ambient air

    Science.gov (United States)

    Wang, Dan; Hu, Renzhi; Xie, Pinhua; Liu, Jianguo; Liu, Wenqing; Qin, Min; Ling, Liuyi; Zeng, Yi; Chen, Hao; Xing, XingBiao; Zhu, Guoliang; Wu, Jun; Duan, Jun; Lu, Xue; Shen, Lanlan

    2015-11-01

    A cavity ring-down spectroscopy (CRDS) instrument for measuring atmospheric NO3 radical developed in our laboratory is presented in detail. Light from a red laser diode (661.85 nm) is coupled on-axis into an optical cavity formed by a pair of high-reflectivity mirrors (R≥99.9985%) to achieve an effective absorption path length of approximately 20 km. The detection limit of the NO3 radical determined by Allan variance for the field observation with high particles is approximately 3.2 pptv (2σ, 10 s). The transmission efficiency of the NO3 radical in the system is calibrated, including the filter loss and surface loss. Moreover, measurable interferences from NO2, O3 and water vapor are also discussed. Considering the influence of inlet transmission efficiency and other factors, the instrument accuracy for NO3 radical measurement is approximately ±8% (1σ). The measurement of NO3 radical was performed at a suburb site in Beijing under the situation of high particles concentration (PM2.5 approximately several tens to 150 μg/m3) from October 26 to November 11, 2014. The NO3 radical concentration during the period is relatively low with the maximum value of 38 pptv. The observation results on October 29, combining NO2, O3 and NO data, are briefly analyzed. The experimental results demonstrate that this compact CRDS instrument has the potential for NO3 radical measurements in the field with high particles.

  3. Ammonia emissions from air cleaners at pig farms in Denmark using a Picarro cavity ring-down spectrometer

    Science.gov (United States)

    Winkler, Renato; Adamsen, Anders Peter S.

    2017-04-01

    Ammonia emissions from agricultural activities such as, cattle, pig and poultry farms have become an ever more important topic both for scientists as well as for regulatory bodies due to the severe impacts of ammonia on human health and the environment. In the European Union, the agricultural sector accounts for most of the ammonia emissions, and therefore the EU authorities have put in place reduction targets for the member states. In Denmark, most pig farmers have to deploy one or more ammonia abatement technologies in order to fulfill the national regulation when building new pig houses. A promising ammonia abatement technology is partial floor ventilation and subsequent cleaning using one or two step chemical air cleaners. The cleaned air will have ammonia concentration is the sub-ppm level and with high humidity. Here we present method of monitoring NH3 emissions from air cleaners deployed on pig farms using the G2103 Picarro laser spectrometer. The Picarro G2103 NH3 analyzer is a high precision cavity ring-down spectrometer using a high finesse optical cavity and a near infra-red light laser light source with a very narrow light band. The latter eliminates cross-interferences from other gases present in livestock air. Picarro instruments are built for field measurements and have been widely used for atmospheric monitoring of greenhouse gases and of air pollutants such as NH3.

  4. Heterodyne pump probe measurements of nonlinear dynamics in an indium phosphide photonic crystal cavity

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Combrié, S.; Lehoucq, G.

    2013-01-01

    Using a sensitive two-color heterodyne pump-probe technique, we investigate the carrier dynamics of an InP photonic crystal nanocavity. The heterodyne technique provides unambiguous results for all wavelength configurations, including the degenerate case, which cannot be investigated with the wid...... with the widely used homodyne technique. A model based on coupled mode theory including two carrier distributions is introduced to account for the relaxation dynamics, which is assumed to be governed by both diffusion and recombination.......Using a sensitive two-color heterodyne pump-probe technique, we investigate the carrier dynamics of an InP photonic crystal nanocavity. The heterodyne technique provides unambiguous results for all wavelength configurations, including the degenerate case, which cannot be investigated...

  5. Gain equalization of FM-EDFA by optimizing ring doping and mode content of the pump with a genetic algorithm

    Science.gov (United States)

    Qiu, Changren; Yang, Tianxin; Jia, Dong fang; Wang, Zhaoying; Ge, Chunfeng

    2015-03-01

    We investigate gain equalization of a four-mode-group and six-mode-group erbium-doped fiber amplifiers with a genetic algorithm for mode division multiplexing transmission systems by optimizing rare earth dopant profile and pump modes powers, respectively. The optimizing gains are calculated to be > 28 dB between 1520 nm - 1565 nm with a maximum differential modal gain of ~ 2 dB among the mode groups only by optimizing the rare earth ring doping profile in the few-mode erbium-doped fiber.

  6. Analytical treatment for the study of an erbium-doped fiber ring laser fed by a sinusoidally modulated pump power

    Science.gov (United States)

    Sola, I. J.; Martín, J. C.; Álvarez, J. M.

    2006-02-01

    An analytical procedure is employed to account for the response of an erbium-doped fiber ring laser whose pump power is sinusoidally modulated. The approximations considered, only strictly valid for very low modulation indexes (of the order of some hundredths), reveal the origin of some relationships between resonances of the main harmonics present in the laser response. However, both experimental and numerical results show how qualitative conclusions concerning relationships between harmonics are also valid for modulation indexes much higher than the ones corresponding to the approximation validity range.

  7. Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter;

    2010-01-01

    Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...... values, suggesting that the model is adequate. Improvement of the 946 nm laser due to the ECDL's narrow spectrum proves to be less significant when compared to its spatial quality, inferring a broad spectrum tapered diode laser pump source may be most practical. Experimental confirmation of such setup...

  8. 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.

  9. CFD simulation of reverse water-hammer induced by collapse of draft-tube cavity in a model pump-turbine during runaway process

    Science.gov (United States)

    Zhang, Xiaoxi; Cheng, Yongguang; Xia, Linsheng; Yang, Jiandong

    2016-11-01

    This paper reports the preliminary progress in the CFD simulation of the reverse water-hammer induced by the collapse of a draft-tube cavity in a model pump-turbine during the runaway process. Firstly, the Fluent customized 1D-3D coupling model for hydraulic transients and the Schnerr & Sauer cavitation model for cavity development are introduced. Then, the methods are validated by simulating the benchmark reverse water-hammer in a long pipe caused by a valve instant closure. The simulated head history at the valve agrees well with the measured data in literature. After that, the more complicated reverse water-hammer in the draft-tube of a runaway model pump-turbine, which is installed in a model pumped-storage power plant, is simulated. The dynamic processes of a vapor cavity, from generation, expansion, shrink to collapse, are shown. After the cavity collapsed, a sudden increase of pressure can be evidently observed. The process is featured by a locally expending and collapsing vapor cavity that is around the runner cone, which is different from the conventional recognition of violent water- column separation. This work reveals the possibility for simulating the reverse water-hammer phenomenon in turbines by 3D CFD.

  10. Active mode locking of quantum cascade lasers operating in external ring cavity

    CERN Document Server

    Revin, D G; Wang, Y; Cockburn, J W; Belyanin, A

    2015-01-01

    Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode locked operation remains a challenge despite dedicated effort. Here we report the first demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents of a standard commercial laser chip.

  11. Implementation of intra-cavity beam shaping technique to enhance pump efficiency

    CSIR Research Space (South Africa)

    Litvin, IA

    2012-02-01

    Full Text Available of the resonator concept. M1 and M2 are flat mirrors; FPTE and FFTB are the lossless phase transformation elements at mirror M1 and M2 respectively. To solve a given problem we must solve the problem of transforming a Super?Gaussian (SG) beam into FT beam... in the cavity. We consider a system consisting of a lens with focal length f and a lossless phase transformation element ?(r) on the plane of mirror M1 which are positioned as a doublet (see fig. 1) [5]. The field at the focal plane of the lens (mirror M2 (see...

  12. Fiber ring resonator with nanofiber section for chiral cavity quantum electrodynamics and multimode strong coupling

    CERN Document Server

    Schneeweiss, Philipp; Hoinkes, Thomas; Rauschenbeutel, Arno; Volz, Jürgen

    2016-01-01

    We experimentally realize an optical fiber ring resonator that includes a tapered section with subwavelength-diameter waist. In this section, the guided light exhibits a significant evanescent field which allows for efficient interfacing with optical emitters. A commercial tunable fiber beam splitter provides simple and robust coupling to the resonator. Key parameters of the resonator such as its out-coupling rate, free spectral range, and birefringence can be adjusted. Thanks to the low taper- and coupling-losses, the resonator exhibits an unloaded finesse of F=75+/-1, sufficient for reaching the regime of strong coupling for emitters placed in the evanescent field. The system is ideally suited for trapping ensembles of laser-cooled atoms along the nanofiber section. Based on measured parameters, we estimate that the system can serve as a platform for optical multimode strong coupling experiments. Finally, we discuss the possibilities of using the resonator for applications based on chiral quantum optics.

  13. Continuous-Wave Cavity Ring-Down Spectroscopy in a Pulsed Uniform Supersonic Flow

    Science.gov (United States)

    Thawoos, Shameemah; Suas-David, Nicolas; Suits, Arthur

    2017-06-01

    We introduce a new approach that couples a pulsed uniform supersonic flow with high sensitivity continuous wave cavity ringdown spectroscopy (UF-CRDS) operated in the near infrared (NIR). This combination is related to the CRESU technique developed in France and used for many years to study reaction kinetics at low temperature, and to the microwave based chirped-pulse uniform supersonic flow spectrometer (CPUF) developed in our group which has successfully demonstrated the use of pulsed uniform supersonic flow to probe reaction dynamics at temperatures as low as 22 K. CRDS operated with NIR permits access to the first overtones of C-H and O-H stretching/bending which, in combination with its extraordinary sensitivity opens new experiments complementary to the CPUF technique. The UF-CRDS apparatus (Figure) utilizes the pulsed uniform flow produced by means of a piezo-electric stack valve in combination with a Laval nozzle. At present, two machined aluminum Laval nozzles designed for carrier gases Ar and He generate flows with a temperature of approximately 25 K and pressure around 0.15 mbar. This flow is probed by an external cavity diode laser in the NIR (1280-1380 nm). Laval nozzles designed using a newly developed MATLAB-based program will be used in the future. A detailed illustration of the novel UF-CRDS instrumentation and its performance will be presented along with future directions and applications. I. Sims, J. L. Queffelec, A. Defrance, C. Rebrion-Rowe, D. Travers, P. Bocherel, B. Rowe, I. W. Smith, J. Chem. Phys. 100, 4229-4241, (1994). C. Abeysekera, B. Joalland, N. Ariyasingha, L. N. Zack, I. R. Sims, R. W. Field, A. G. Suits, J. Phys. Chem. Lett. 6, 1599-1604, (2015). N. Suas-David, T. Vanfleteren, T. Foldes, S. Kassi, R. Georges, M. Herman, J. Phys. Chem.A, 119, 10022-10034, (2015). C. Abeysekera, B. Joalland, Y. Shi, A. Kamasah, J. M. Oldham, A. G. Suits, Rev. Sci. Instrum. 85, 116107, (2014).

  14. 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.

  15. Tin re-deposition and erosion measured by cavity-ring-down-spectroscopy under a high flux plasma beam

    Science.gov (United States)

    Kvon, V.; Al, R.; Bystrov, K.; Peeters, F. J. J.; van de Sanden, M. C. M.; Morgan, T. W.

    2017-08-01

    Cavity-ring-down spectroscopy (CRDS) was implemented to measure the re-deposition of liquid tin under a high flux plasma beam in the linear plasma device Pilot-PSI. A capillary porous system (CPS) consisting of a molybdenum cup and tungsten meshes (pores diameters of 0.2 mm and 0.44 mm) was filled with tin and exposed to argon plasma. The absorption of a UV laser-beam at 286.331 nm was used to determine a number of sputtered neutral tin atoms. The incoming flux of argon ions of ~50 eV was 1.6-2.7  ×  1023 m-2 s-1, and the sample temperature measured by pyrometry varied from 850 °C to 1200 °C during exposures. The use of CRDS for measuring absolute number of particles under such plasma exposure was demonstrated for the first time. The number of sputtered tin particles in the cavity region assuming no losses would be expected to be 5.5  ×  1011-1.2  ×  1012 while CRDS measurements showed only 5.7-9.9  ×  108. About 98-99.8% of sputtered particles were therefore found to not reach the CRDS observation volume. Spectroscopic ratios of Sn I to Sn II ions, as well as equilibrium considerations, indicate that fast ionization as well as plasma entrainment of neutrals is responsible for the discrepancy. This would lead to high re-deposition rates, implying a lowered contamination rate of core plasma and lower required replenishment rates at high-flux conditions than would otherwise be expected.

  16. A cavity ring-down spectroscopy system for high time resolution measurements of gaseous elemental mercury concentrations

    Science.gov (United States)

    Pierce, Ashley M.

    The global cycling of mercury (Hg), a highly toxic environmental pollutant, currently has many unknowns. There are various sources of Hg to the atmosphere including both anthropogenic and natural sources. Processes involved in the global cycling of Hg include emissions from legacy Hg pools, deposition, re-emission, and chemical and physical transformation processes such as gas-phase oxidation and heterogeneous redox reactions. Gaseous elemental mercury (GEM) can represent >95% of Hg present in the atmosphere. GEM has a relatively long atmospheric lifetime, which allows it to be transported 1000s of km, effectively making it a global pollutant. Once deposited, Hg can be converted to methylmercury, a bioavailable form of Hg known to cause neurological damage in wildlife and humans. Current atmospheric Hg sensors require long analyzing periods for a single sample (minutes to hours), thus a faster-response sensor would improve characterization of surface-atmosphere exchange processes and atmospheric Hg dynamics. The goal of this thesis work was to develop a new, field-deployable sensor for high time resolution measurements of GEM in ambient air using pulsed cavity ring-down spectroscopy (CRDS). In this research, a CRDS system was developed using a pulsed laser (50 Hz pulse repetition rate) emitting wavelengths tunable between 215 and 280 nm (Hg absorbs at 253.65 nm), a high finesse 1-m-long cavity lined with two high reflectivity mirrors. Due to the long path length (˜1 km) produced inside the short cavity, sample volumes could be kept small while measurement sensitivity remained high. By optimizing the CRDS setup and reducing interferences (e.g., ozone concentration fluctuations), the current CRDS sensor was deployed in the field to measure GEM concentrations in ambient air. The sensor was also used for the first-ever GEM flux measurements by the eddy covariance flux method. Results showed that fast GEM fluctuations could be detected by the CRDS sensor and the

  17. Nd:YAG solid-state ring laser pumped by a light-emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Belozerov, S.A.; Kornienko, L.S.; Kravtsov, N.V.; Kuratev, I.I.; Rusakov, S.I.; Stel' makh, M.F.; Shelaev, A.A.; Shelaev, A.I.

    1984-01-01

    This letter reports lasing in an Nd:YAG solid-state laser (lambda = 1.06 ..mu..m) pumped either in pulses or continuously by a light-emitting diode. We report the first experimental results on this laser.(AIP)

  18. Sealing Mechanism and Use of O-ring for Hydraulic Gear Pump%液压齿轮泵中O形圈密封机理和选用

    Institute of Scientific and Technical Information of China (English)

    周亚东

    2015-01-01

    该文对液压齿轮泵中的O形圈的密封机理进行了简要分析,并给出O形圈选用时的一些注意事项。%This article simple analysis sealing mechanism of O-ring which used in Hydraulic Gear Pump, and gives some notes of how to choose O-ring.

  19. A free-flowing soap film combined with cavity ring-down spectroscopy as a detection system for liquid chromatography.

    Science.gov (United States)

    Vogelsang, Markus; Welsch, Thomas; Jones, Harold

    2010-05-07

    We have shown that a free-flowing soap film has sufficiently high-quality optical properties to allow it to be used in the cavity of a ring-down spectrometer (CRDS). The flow rates required to maintain a stable soap film were similar to those used in liquid chromatography and thus allowed interfacing with an HPLC system for use as an optical detector. We have investigated the properties of the system in a relevant analytical application. The soap film/CRDS combination was used at 355 nm as a detector for the separation of a mixture of nitroarenes. These compounds play a role in the residue analysis of areas contaminated with explosives and their decomposition products. In spite of the short absorption path length (9 microm) obtained by the soap film, the high-sensitivity of CRDS allowed a limit of detection of 4 x 10(-6) in absorption units (AU) or less than 17 fmol in the detection volume to be achieved.

  20. Isotopic Seawater Analysis Using Cavity Ring-Down Spectroscopy: Method for Reducing the Effect of Salts on the Measurements

    Science.gov (United States)

    Kim-Hak, D.; Normandeau, C.; Winkler, R.; Huang, K.; Kerrigan, L.

    2015-12-01

    High-salinity waters such as Seawater poses an operational and maintenance challenge to the measurements of water stable isotopes via Cavity Ring-Down Spectroscopy. As liquid samples are evaporated in the vaporizer peripheral before being sent to the CRDS analyzer, salt precipitates accumulate in the vaporizer chamber. As a result, the sample-to-sample memory performance degrades over time and frequent cleaning is required to maintain the peripheral performance and integrity. To address this issue, earlier work showed that adding a metallic mesh liner into the injection port of the vaporizer could capture salt solids and protect the vaporizer chamber without affecting the sample's isotopic composition and the measurement performance. Additional long-term tests have been recently conducted with the new commercially available Salt Liner accessory to assess its efficacy. We demonstrated the longer stability of the sample-to-sample memory performance on various brine water measurements when compared to a system without the Salt Liner. We also established the guidelines in using, replacing, and cleaning the Salt Liner.

  1. Temperature Dependence of Near-Infrared CO_2 Line Shapes Measured by Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Ghysels, Mélanie; Fleisher, Adam J.; Liu, Qingnan; Hodges, Joseph T.

    2017-06-01

    We present high signal-to-noise ratio, mode-by-mode cavity ring-down spectroscopy (CRDS) line shape measurements of air-broadened transitions in the 30013 → 0001 band of ^{12}C^{16}O_2 located near λ = 1.6 μm. Absorption spectra were acquired from (230-290) K with a variable-temperature spectrometer developed in the framework of the NASA Orbiting Carbon Observatory-2 Mission to improve our understanding of carbon dioxide and oxygen line shape parameters. This system comprises a monolithic, thermally stabilized two-mirror, optical resonator exhibiting a mode stability of 200 kHz and a minimum detectable absorption coefficient of 10^{-11} cm^{-1}. Observed spectra were modeled the using the recently recommended Hartmann-Tran line profile (HTP) (and several of its limiting cases) which includes the effects of Dicke narrowing, speed dependent broadening, correlation between velocity- and phase-changing collisions and first-order line mixing effects. At fixed temperature, line shape parameters were determined by constrained multispectrum fitting of spectra acquired over the pressure range (30 - 300) Torr. For each transition considered, analysis of the temperature dependence of the fitted line shape parameters yielded the pressure-broadening temperature exponent and speed dependence parameter, where the latter quantity was found to be in good agreement with theoretical values consistent with the HTP model. Tennyson, et al., Pure Appl. Chem. 86, (2014) 1931

  2. Modification of a commercial cavity ring-down spectroscopy NO{sub 2} detector for enhanced sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos, Patricia; Ehrman, Sheryl H. [Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742 (United States); Luke, Winston T.; Kelley, Paul [National Oceanic and Atmospheric Administration, Air Resources Laboratory, SSMC3, Rm. 3316, 1315 East West Hwy., Silver Spring, Maryland 20910 (United States); Stehr, Jeffrey W.; Dickerson, Russell R. [Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland 20742 (United States)

    2009-11-15

    Nitrogen dioxide (NO{sub 2}) plays a central role in atmospheric chemistry, air pollution, and biogeochemical cycles. Many analytical techniques have been developed to detect NO{sub 2}, but only chemiluminescence-based instruments are commonly, commercially available. There remains a need for a fast, light, and simple method to directly measure NO{sub 2}. In this work we describe the modification and characterization of a small, commercially available cavity ring-down spectroscopy (CRDS) NO{sub 2} detector suitable for surface and aircraft monitoring. A metal oxide scrubber was added to remove NO{sub 2}, and provide a chemical zero, improving the detection limit (3{sigma} of the background noise) from several parts per billion by volume (ppbv) to 0.06 ppbv, integrated over 60 s. Known interferences by water and particles were removed using Nafion tubing and a 1 {mu}m Teflon filter, respectively. A 95% response time of 18{+-}1 s was observed for a step change in concentration. The CRDS detector was run in parallel to an ozone chemiluminescence device with photolytic conversion of NO{sub 2} to NO. The two instruments measured ambient air in suburban Maryland. A least-squares fit to the comparison data resulted a slope of 0.960{+-}0.002 and R of 0.995, showing agreement within experimental uncertainty.

  3. Phase-shift Cavity Ring Down Spectroscopy Set-up for NO2 Sensing : Design and Fabrication

    Directory of Open Access Journals (Sweden)

    Cherry Dhiman

    2015-03-01

    Full Text Available An indigenously designed cavity ring down spectroscopy cell of 80 cm length of mild steel material was fabricated by attaching two 1″ diameter high reflecting concave mirrors with reflectivity 99.997 % at 405 nm and radius of curvature was 1 m in specially designed mirror holding assemblies to the cell at two ends. Fine alignment of the resonator is facilitated with three tip-tilt adjusting screws to the mirror-mounting plate assembly. The PS-CRDS experimental set-up is evaluated by measuring the phase shift values corresponding to the absorption of NO2 gas filled at low pressures in the cell. The limit of detection of pure NO2 using the set-up under given conditions of Ar @ 50 mbar is estimated to be 1.50 × 1011 cm-3 and @ 60 mbar as 2 × 1011 cm-3.Defence Science Journal, Vol. 65, No. 1, January 2015, pp.25-30, DOI:http://dx.doi.org/10.14429/dsj.65.7790

  4. Compositional and Optical Properties of Titan Haze Analogs Using Aerosol Mass Spectrometry, Photoacoustic Spectroscopy and Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Ugelow, M.; Zarzana, K. J.; Tolbert, M. A.

    2015-12-01

    The organic haze that surrounds Saturn's moon Titan is formed through the photolysis and electron initiated dissociation of methane and nitrogen. The chemical pathways leading to haze formation and the resulting haze optical properties are still highly uncertain. Here we examine the compositional and optical properties of Titan haze aerosol analogs. By studying these properties together, the impact of haze on Titan's radiative balance can be better understood. The aerosol analogs studied are produced from different initial methane concentrations (0.1, 2 and 10% CH4) using spark discharge excitation. To determine the complex refractive index of the aerosol, we combine two spectroscopic techniques, one that measures absorption and one that measures extinction: photoacoustic spectroscopy coupled with cavity ring-down spectroscopy (PASCaRD). This technique provides the benefit of a high precision determination of the imaginary component of the refractive index (k), along with the highly sensitive determination of the real component of the refractive index (n). The refractive indices are retrieved at two wavelengths, 405 and 532 nm, using the PASCaRD system. To yield aerosol composition, quadrupole aerosol mass spectrometry is used. Compositional information is obtained from a technique that uses isotopically labeled and unlabeled methane gas. I will present preliminary data on the complex refractive indices of Titan aerosol analogs at both wavelengths, in conjunction with the aerosol composition as a percent by weight of carbon, nitrogen and hydrogen. The correlation of optical and chemical properties should be useful for remote sensing instruments probing Titan haze.

  5. Determination of δ2H and δ18O in mineral water based on Cavity Ring-Down Spectrometry

    Science.gov (United States)

    Tonietto, G.; Godoy, J.; Godoy, M. L.

    2013-12-01

    Stable isotopes of water are proven indicators, tracers and recorders of processes that affect the hydrologic cycle. Measurements of the stable isotope ratios (δ2H, δ18O and δ17O) of both liquid water and water vapor are widely used in hydrology, atmospheric sciences, and biogeochemistry to determine the migration of water through an ecosystem. Application of the method to Brazilian bottled mineral water has shown that it is possible to trace the origin of the water to at least the state level within Brazilian geographical regions. National and regional meteoric water lines were constructed with substantial differences between geographical regions, in particular for the central region of the country, with a slope coefficient of approximately seven and no deuterium excess. The repeatability, reproducibility and accuracy of the direct measurement of δ2H and δ18O isotopes in water samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample analysis was approximately 7 minutes. The new high throughput method measures isotopologues of water with a typical precision of better than 0.15‰ for δ18O and better than 0.6‰ for δ2H.

  6. Fugitive methane emission pinpointing and source attribution using ethane measurements in a portable cavity ring-down analyzer

    Science.gov (United States)

    Fleck, Derek; Hoffnagle, John; Yiu, John; Chong, Johnston; Tan, Sze

    2017-04-01

    Methane source pinpointing and attribution is ever more important because of the vast network of natural gas distribution which has led to a very large emission sources. Ethane can be used as a tracer to distinguish gas sources between biogenic and natural gas. Having this measurement sensitive enough can even distinguish between gas distributors, or maturity through gas wetness. Here we present data obtained using a portable cavity ring-down spectrometer weighing less than 11 kg and consuming less than 35W that simultaneously measures methane and ethane with a raw 1-σ precision of 50ppb and 4.5ppb, respectively at 2 Hz. These precisions allow for a C2:C1 ratio 1-σ measurement of right above the ground, correlations in the variations in C2H6 and CH4 are used to derive a source C2:C1. Additional hardware is needed for steady state concentration measurements to reliably measure the C2:C1 ratio instantaneously. Source discrimination data of local leaks and methane sources using this analysis method are presented. Additionally, two-dimensional plume snapshots are constructed using an integrated onboard GPS to visualize horizontal plane gas propagation.

  7. The application of a cavity ring-down spectrometer to measurements of ambient ammonia using traceable primary standard gas mixtures

    Science.gov (United States)

    Martin, Nicholas A.; Ferracci, Valerio; Cassidy, Nathan; Hoffnagle, John A.

    2016-08-01

    A correction for the undesirable effects of direct and indirect cross-interference from water vapour on ammonia (NH3) measurements was developed using an optical laser sensor based on cavity ring-down spectroscopy. This correction relied on new measurements of the collisional broadening due to water vapour of two NH3 spectral lines in the near infra-red (6548.6 and 6548.8 cm-1), and on the development of novel stable primary standard gas mixtures (PSMs) of ammonia prepared by gravimetry in passivated gas cylinders at 100 μmol mol-1. The PSMs were diluted dynamically to provide calibration mixtures of dry and humidified ammonia atmospheres of known composition in the nmol mol-1 range and were employed as part of establishing a metrological traceability chain to improve the reliability and accuracy of ambient ammonia measurements. The successful implementation of this correction will allow the extension of this rapid on-line spectroscopic technique to exposure chamber validation tests under controlled conditions and ambient monitoring in the field.

  8. 101 W of average green beam from diode-side-pumped Nd:YAG/LBO-based system in a relay imaged cavity

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak

    2010-11-01

    Studies on intracavity frequency doubling of acousto-optically Q-switched Nd:YAG rod laser using 18 mm long type-II phase-matched LBO crystal in a relay-imaged cavity is reported. A single pump head comprised of Nd:YAG rod, diffusive reflectors and linear array laser diode bars is used. 101 W of average green power at a total diode pumping power of 700 W is obtained corresponding to 14.4% optical-to-optical conversion efficiency. The pulse repetition rate is 30 kHz with an individual pulse duration of 200 ns.

  9. Cavity-induced microstreaming for simultaneous on-chip pumping and size-based separation of cells and particles.

    Science.gov (United States)

    Patel, Maulik V; Nanayakkara, Imaly A; Simon, Melinda G; Lee, Abraham P

    2014-10-07

    We present a microfluidic platform for simultaneous on-chip pumping and size-based separation of cells and particles without external fluidic control systems required for most existing platforms. The device utilizes an array of acoustically actuated air/liquid interfaces generated using dead-end side channels termed Lateral Cavity Acoustic Transducers (LCATs). The oscillating interfaces generate local streaming flow while the angle of the LCATs relative to the main channel generates a global bulk flow from the inlet to the outlet. The interaction of these two competing velocity fields (i.e. global bulk velocity vs. local streaming velocity) is responsible for the observed separation. It is shown that the separation of 5 μm and 10 μm polystyrene beads is dependent on the ratio of these two competing velocity fields. The experimental and simulation results suggest that particle trajectories based only on Stokes drag force cannot fully explain the separation behavior and that the impact of additional forces due to the oscillating flow field must be considered to determine the trajectory of the beads and ultimately the separation behavior of the device. To demonstrate an application of this separation platform with cellular components, smaller red blood cells (7.5 ± 0.8 μm) are separated from larger K562 cells (16.3 ± 2.0 μm) with viabilities comparable to those of controls based on a trypan blue exclusion assay.

  10. Femtosecond Laser Pumped Conical Emission and Seeded Ring Amplification in BBO Crystals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-Sen; LI Feng-Ming; WANG Shu-Feng; GONG Qi-Huang

    2005-01-01

    @@ The characteristics of femtosecond laser pumped conical emission in quadratic media of β-barium borate (BBO)crystals are analysed. A minimized dispersion phase-matching angle, by which a wide-range spectrum can be obtained, is used for broadband amplification. When a seed of a chirped supercontinuum pulse is input, it is found that the seed in wavelength 500nm-750nm is amplified and time resolved.

  11. 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.

  12. CAVITY RING-DOWN SPECTROSCOPY AND HIGH SENSITIVITY ABSORPTION MEASUREMENT%光腔衰荡技术与高灵敏吸收探测

    Institute of Scientific and Technical Information of China (English)

    赵宏太; 柳晓军; 詹明生

    2001-01-01

    腔衰荡光谱技术是一种新兴的高灵敏吸收光谱探测技术,已经被广泛地应用于原子、分子、团簇等吸收光谱的测量,且可实现10-6-10-14cm-1量级吸收的测量.文章综述了腔衰荡光谱技术的发展及在吸收光谱探测上的应用.%Cavity ring-down spectroscopy is a novel spectroscopic techniqueused for high-sensitivity measurement of absorption. It has been widely used in atomic, molecular and cluster spectroscopy, with an absorption sensitivity of 10-6-10-14cm-1. The development of the cavity ring-down technology and its application in absorption measurement are reviewed.

  13. A cavity ring-down spectroscopy sensor for measurements of gaseous elemental mercury – Part 1: Development for high time resolution measurements in ambient air

    OpenAIRE

    X. Faïn; D. Obrist; H. Moosmüller; Pierce, A; Moore, C.

    2012-01-01

    The ability to make high time resolution measurements of gaseous elemental mercury (GEM) concentrations in air is imperative for the understanding of mercury cycling. Here we describe further development and field implementation of a laboratory prototype pulsed cavity ring-down spectroscopy (CRDS) system for high time resolution, continuous and automated measurement of GEM concentrations in ambient air. In particular, we present use of an external, isotopically enriched Hg cell for automated ...

  14. Effects of geometry and linearly polarized cavity photons on charge and spin currents in a quantum ring with spin-orbit interactions

    Science.gov (United States)

    Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2014-05-01

    We calculate the persistent charge and spin polarization current inside a finite-width quantum ring of realistic geometry as a function of the strength of the Rashba or Dresselhaus spin-orbit interaction. The time evolution in the transient regime of the two-dimensional (2D) quantum ring connected to electrically biased semi-infinite leads is governed by a time-convolutionless non-Markovian generalized master equation. The electrons are correlated via Coulomb interaction. In addition, the ring is embedded in a photon cavity with a single mode of linearly polarized photon field, which is polarized either perpendicular or parallel to the charge transport direction. To analyze carefully the physical effects, we compare to the analytical results of the toy model of a one-dimensional (1D) ring of non-interacting electrons with spin-orbit coupling. We find a pronounced charge current dip associated with many-electron level crossings at the Aharonov-Casher phase ΔΦ = π, which can be disguised by linearly polarized light. Qualitative agreement is found for the spin polarization currents of the 1D and 2D ring. Quantitatively, however, the spin polarization currents are weaker in the more realistic 2D ring, especially for weak spin-orbit interaction, but can be considerably enhanced with the aid of a linearly polarized electromagnetic field. Specific spin polarization current symmetries relating the Dresselhaus spin-orbit interaction case to the Rashba one are found to hold for the 2D ring, which is embedded in the photon cavity.

  15. Water Vapor Self-Continuum by Cavity Ring Down Spectroscopy in the 1.6 Micron Transparency Window

    Science.gov (United States)

    Campargue, Alain; Kassi, Samir; Mondelain, Didier

    2014-06-01

    Since its discovery one century ago, a deep and unresolved controversy remains on the nature of the water vapor continuum. Several interpretations are proposed: accumulated effect of the distant wings of many individual spectral lines, metastable or true bound water dimers, collision-induced absorption. The atmospheric science community has largely sidestepped this controversy, and has adopted a pragmatic approach: most radiative transfer codes used in climate modelling, numerical weather prediction and remote sensing use the MT_CKD model which is a semi-empirical formulation of the continuum The MT_CKD cross-sections were tuned to available observations in the mid-infrared but in the absence of experimental constraints, the extrapolated near infrared (NIR) values are much more hazardous. Due to the weakness of the broadband absorption signal to be measured, very few measurements of the water vapor continuum are available in the NIR windows especially for temperature conditions relevant for our atmosphere. This is in particular the case for the 1.6 μm window where the very few available measurements show a large disagreement. Here we present the first measurements of the water vapor self-continuum cross-sections in the 1.6 μm window by cavity ring down spectroscopy (CRDS). The pressure dependence of the absorption continuum was investigated during pressure cycles up to 12 Torr for selected wavenumber values. The continuum level is observed to deviate from the expected quadratic dependence with pressure. This deviation is interpreted as due to a significant contribution of water adsorbed on the super mirrors to the cavity loss rate. The pressure dependence is well reproduced by a second order polynomial. We interpret the linear and quadratic terms as the adsorbed water and vapour water contribution, respectively. The derived self-continuum cross sections, measured between 5875 and 6450 wn, shows a minimum value around 6300 wn. These cross sections will be compared

  16. 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%.

  17. 5.5 W continuous-wave TEM00-mode Nd:YAG solar laser by a light-guide/2V-shaped pump cavity

    Science.gov (United States)

    Almeida, J.; Liang, D.; Vistas, C. R.; Bouadjemine, R.; Guillot, E.

    2015-12-01

    A significant progress in TEM00-mode solar laser power and efficiency with heliostat-parabolic mirror system is reported here. A double-stage light-guide/2V-shaped pump cavity is used to efficiently couple and redistribute the concentrated pump light from a 2-m-diameter parabolic mirror to a 4-mm-diameter, 30-mm-length, 1.1 at.% Nd:YAG single-crystal rod. The light guide with large rectangular cross section enables a stable uniform pumping profile along the laser rod, resulting also in an enhanced tracking error compensation capacity. 5.5 W cw TEM00-mode solar laser power was measured at the output of a thermally near unstable asymmetric resonator. 150 and 157 % improvement in TEM00-mode solar laser collection efficiency and slope efficiency were obtained, respectively.

  18. A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

    Directory of Open Access Journals (Sweden)

    T. W. Tokarek

    2014-06-01

    Full Text Available The peroxycarboxylic nitric anhydrides (PANs, molecular formula RC(OO2NO2 can readily be observed by gas chromatography coupled to electron capture detection (PAN-GC. Calibration of a PAN-GC remains a challenge because the response factors (RF's differ for each of the PANs and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ring-down spectroscopy (TD-CRDS, are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate (ΣPN mixing ratios measured by TD-CRDS (r > 0.96. Accurate determination of RF's required the concentrations of PAN impurities in the synthetic standards to be subtracted from ΣPN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August, 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. For the Abbotsford data set, the PAN-GC mixing ratios were compared and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS. Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.

  19. Ultra-Sensitive Elemental and Isotope Measurements with Compact Plasma Source Cavity Ring-Down Spectroscopy (CPS-CRDS)

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Yixiang; Wang, Chuji; Winstead, Christopher B.

    2005-06-01

    The proposed research is to develop a new class of instruments for actinide isotopes and hazardous element analysis through coupling highly sensitive cavity ring-down spectroscopy to a compact microwave plasma source. The research work will combine advantages of CRDS measurement with a low power, low flow rate, tubing-type microwave plasma source to reach breakthrough sensitivity for elemental analysis and unique capability of isotope measurement. The project has several primary goals: (1) Explore the feasibility of marrying CRDS with a new microwave plasma source; (2) Provide quantitative evaluation of CMP-CRDS for ultratrace elemental and actinide isotope analysis; (3) Approach a breakthrough detection limit of ca. 10{sup -13} g/ml or so, which are orders of magnitude better than currently available best values; (4) Demonstrate the capability of CMP-CRDS technology for isobaric measurements, such as {sup 238}U and {sup 238}Pu isotopes. (5) Design and assemble the first compact, field portable CMP-CRDS instrument with a high-resolution diode laser for DOE/EM on-site demonstration. With all these unique capabilities and sensitivities, we expect CMP-CRDS will bring a revolutionary change in instrument design and development, and will have great impact and play critical roles in supporting DOE's missions in environmental remediation, environmental emission control, waste management and characterization, and decontamination and decommissioning. The ultimate goals of the proposed project are to contribute to environmental management activities that would decrease risk for the public and workers, increase worker productivity with on-site analysis, and tremendously reduce DOE/EM operating costs.

  20. Measurements of methane emissions from landfills using mobile plume method with trace gas and cavity ring-down spectroscopy

    Science.gov (United States)

    Mønster, J.; Kjeldsen, P.; Scheutz, C.

    2012-04-01

    Methane is emitted to the atmosphere from both anthropogenic and natural sources. One of the major anthropogenic sources is methane produced by bacteria in anaerobic environments such as rice pads and landfills. Land filling has for many years been the preferred waste disposal method, resulting in a large methane production with a large contribution to the global increase in atmospheric green house gas concentration. Several steps have been taken to reduce the emission of methane from landfills. In order to validate the effect of these steps, a measurement method is needed to quantify methane emissions with a large spatial variation. One method is to use a highly sensitive and fast analytical method, capable of measuring the atmospheric concentration methane downwind from emission areas. Combined with down-wind measurements of a trace gas, emitted at a controlled mass flow rate, the methane emission can be calculated. This method is called the mobile plume method, as the whole plume is measured by doing several transects. In the current study a methane/acetylene analyzer with cavity ring-down spectroscopy detection (Picarro, G2203) was used to estimate methane from a number of Danish landfills. We measured at both active and closed landfills and investigated the difference in methane emission. At landfills where the emissions could have more than one origin, the source strength of the different emission areas was determined by accurate trace gas positioning and choosing appropriate wind speed and measurement distance. To choose these factors, we addressed the uncertainties and limitations of the method with respect to the configuration of the trace gas bottles and the distance between the emission area and the measurement points. Composting of organic material in large piles was done at several of the investigated landfills and where possible, the methane emission from this partly anaerobic digestion was measured as a separate emission.

  1. Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS technique

    Directory of Open Access Journals (Sweden)

    H. Chen

    2012-09-01

    Full Text Available Accurate measurements of carbon monoxide (CO in humid air have been made using the cavity ring-down spectroscopy (CRDS technique. The measurements of CO mole fractions are determined from the strength of its spectral absorption in the near infrared region (∼1.57 μm after removing interferences from adjacent carbon dioxide (CO2 and water vapor (H2O absorption lines. Water correction functions that account for the dilution and pressure-broadening effects as well as absorption line interferences from adjacent CO2 and H2O lines have been derived for CO2 mole fractions between 360–390 ppm. The line interference corrections are independent of CO mole fractions. The dependence of the line interference correction on CO2 abundance is estimated to be approximately −0.3 ppb/100 ppm CO2 for dry mole fractions of CO. Comparisons of water correction functions from different analyzers of the same type show significant differences, making it necessary to perform instrument-specific water tests for each individual analyzer. The CRDS analyzer was flown on an aircraft in Alaska from April to November in 2011, and the accuracy of the CO measurements by the CRDS analyzer has been validated against discrete NOAA/ESRL flask sample measurements made on board the same aircraft, with a mean difference between integrated in situ and flask measurements of −0.6 ppb and a standard deviation of 2.8 ppb. Preliminary testing of CRDS instrumentation that employs new spectroscopic analysis (available since the beginning of 2012 indicates a smaller water vapor dependence than the models discussed here, but more work is necessary to fully validate the performance. The CRDS technique provides an accurate and low-maintenance method of monitoring the atmospheric dry mole fractions of CO in humid air streams.

  2. H2S interference on CO2 isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer

    Directory of Open Access Journals (Sweden)

    K. Malowany

    2015-06-01

    Full Text Available Cavity ring-down spectrometers (CRDS have the capacity to make isotopic measurements of CO2 where concentrations range from atmospheric (~ 400 ppm to 6000 ppm. Following field trials, it has come to light that the spectrographic lines used for CO2 have an interference with elevated (higher than ambient amounts of hydrogen sulfide (H2S, which causes significant depletions in the δ13C measurement by the CRDS. In order to deploy this instrument in environments with elevated H2S concentrations (i.e., active volcanoes, we require a robust method for eliminating this interference. Controlled experiments using a Picarro G1101-i optical spectrometer were done to characterize the H2S interference at varying CO2 and H2S concentrations. The addition of H2S to a CO2 standard gas reveals an increase in the 12CO2 concentration and a more significant decrease in the 13CO2 concentration, resulting in a depleted δ13C value. Reacting gas samples containing H2S with copper prior to analysis can eliminate this effect. However, experiments also revealed that the addition of H2S to CO2 results in the formation of carbonyl sulfide (OCS and carbon disulfide (CS2, causing a decrease in the overall CO2 concentration without affecting the δ13C value. It is important for future work with CRDS, particularly in volcanic regions where H2S is abundant, to be aware of the H2S interference on the CO2 spectroscopic lines and to remove all H2S prior to analysis. We suggest employing a scrub composed of copper to remove H2S from all gas samples that have concentrations in excess of 1 ppb.

  3. Isotopic analysis of dissolved organic carbon in produced water brines by wet chemical oxidation and cavity ring-down spectroscopy

    Science.gov (United States)

    Thomas, Randal; Conaway, Christopher; Saad, Nabil; Kharaka, Yousif

    2013-04-01

    Identification of fluid migration and escape from intentionally altered subsurface geologic systems, such as in hydraulic fracturing, enhanced oil recovery, and carbon sequestration activities, is an important issue for environmental regulators based on the traction that the "fracking" process is gathering across the United States. Given diverse injected fluid compositions and the potential for toxic or regulated compounds to be released, one of the most important steps in the process is accurately identifying evidence of injected fluid escape during and after injection processes. An important tool in identifying differences between the natural groundwater and injected fluid is the isotopic composition of dissolved constituents including inorganic components such as Sr and carbon isotopes of the dissolved organic compounds. Since biological processes in the mesothermal subsurface can rapidly alter the organic composition of a fluid, stable carbon isotopes of the dissolved organic compounds (DOC) are an effective means to identify differences in the origin of two fluids, especially when coupled with inorganic compound analyses. The burgeoning field of cavity ring-down spectroscopy (CRDS) for isotopic analysis presents an opportunity to obtain rapid, reliable and cost-effective isotopic measurements of DOC in potentially affected groundwater for the identification of leakage or the improvement of hydrogeochemical pathway models. Here we adapt the use of the novel hyphenated TOC-CRDS carbon isotope analyzer for the analysis of DOC in produced water by wet oxidation and describe the methods to evaluate performance and obtain useful information at higher salinities. Our methods are applied to a specific field example in a CO2-enhanced EOR field in Cranfield, Mississippi (USA) as a means to demonstrate the ability to distinguish natural and injected DOC using the stable isotopic composition of the dissolved organic carbon when employing the novel TOC-CRDS instrumentation

  4. Cavity ring-down spectroscopy sensor development for high-time-resolution measurements of gaseous elemental mercury in ambient air

    Directory of Open Access Journals (Sweden)

    A. Pierce

    2013-06-01

    Full Text Available We describe further development of a previous laboratory prototype pulsed cavity ring-down spectroscopy (CRDS sensor into a field-deployable system for high-time-resolution, continuous, and automated measurement of gaseous elemental mercury (GEM concentrations in ambient air. We employed an external, isotopically enriched Hg cell for automated locking and stabilization of the laser wavelength on the GEM peak absorption during measurements. Further, we describe implementation of differential absorption measurements via a piezoelectric tuning element for pulse-by-pulse tuning of the laser wavelength onto and off of the GEM absorption line. This allowed us to continuously correct (at 25 Hz for system baseline extinction losses unrelated to GEM absorption. Extensive measurement and calibration data obtained with the system were based on spike addition in both GEM-free air and ambient air. Challenges and interferences that occurred during measurements (particularly in ambient air are discussed including temperature and ozone (O3 concentration fluctuations, and steps taken to reduce these. CRDS data were highly linear (r2 ≥ 0.98 with data from a commercial Tekran 2537 Hg analyzer across a wide range of GEM concentrations (0 to 127 ng m−3 in Hg-free and ambient air. Measurements during periods of stable background GEM concentrations provided a conservative instrument sensitivity estimate of 0.35 ng m−3 for the CRDS system when time averaged for 5 min. This sensitivity, along with concentration patterns observed in ambient air (with the CRDS system and verified with the Tekran analyzer, showed that the sensor was capable of characterizing GEM fluctuations in ambient air. The value of fast-response GEM measurements was shown by a series of GEM spike additions – highlighting that high-temporal-resolution measurement allowed for detailed characterization of fast concentration fluctuations not possible with traditional analyzers.

  5. Electron beam pumped III-V nitride vertical cavity surface emitting lasers grown by molecular beam epitaxy

    Science.gov (United States)

    Ng, Hock Min

    The design and fabrication by molecular beam epitaxy of a prototype vertical cavity laser based on the III-V nitrides were investigated in this work. The bottom mirror of the laser consists of distributed Bragg reflectors (DBRs) based on quarterwave AlN (or AlxGa1-xN) and GaN layers. Such DBRs were designed for maximum reflectivity in the spectral region from 390--600 nm. The epitaxial growth of these two binaries on each other revealed that while AlN grows on GaN in a two-dimensional mode (Frank-van der Merwe mode), GaN grows on AlN in a three-dimensional mode (Stranski-Krastanov mode). In spite of that, DBRs with peak reflectance up to 99% and bandwidths of 45nm were fabricated. The measured reflectance spectra were compared with simulations using the transmission matrix method. The mechanical stability of these DBR structures due to non-uniform distribution of strain arising from lattice or thermal mismatch of the various components were also addressed. The active region of the laser consists of InGaN/GaN multiple quantum wells (MQWs). The existence of up to the third order diffraction peaks in the x-ray diffraction spectra suggests that the interfaces between InGaN and GaN are sharp with little interdiffusion at the growth temperature. The photoluminescence and cathodoluminescence spectra were analyzed to determine the optical quality of the MQWs. The best MQWs were shown to have a single emission peak at 397nm with full width half maximum (FWHM) of 11nm. Cathodoluminescence studies showed that there are spatially localized areas of intense light emission. The complete device was formed on (0001) sapphire substrates using the previously described DBRs as bottom mirrors and the MQWs as the active region. The top mirror of the device consists of metallic silver. The device was pumped by an electron beam from the top mirror side and the light output was collected from the sapphire side. Measurements at 100K showed narrowing of the linewidth with increasing pump

  6. High-frequency isotopic analysis of liquid water samples in the field - initial results from continuous water sampling and cavity ring-down spectroscopy

    Science.gov (United States)

    von Freyberg, Jana; Studer, Bjørn; Kirchner, James

    2016-04-01

    Studying rapidly changing hydrochemical signals in catchments can help to improve our mechanistic understanding of their water flow pathways and travel times. For these purposes, stable water isotopes (18O and 2H) are commonly used as natural tracers. However, high-frequency isotopic analyses of liquid water samples are challenging. One must capture highly dynamic behavior with high precision and accuracy, but the lab workload (and sample storage artifacts) involved in collecting and analyzing thousands of bottled samples should also be avoided. Therefore, we have tested Picarro, Inc.'s newly developed Continuous Water Sampler Module (CoWS), which is coupled to their L2130-i Cavity Ring-Down Spectrometer to enable real-time on-line measurements of 18O and 2H in liquid water samples. We coupled this isotope analysis system to a dual-channel ion chomatograph (Metrohm AG, Herisau, Switzerland) for analysis of major cations and anions, as well as a UV-Vis spectroscopy system (s::can Messtechnik GmbH, Vienna, Austria) and electrochemical probes for characterization of basic water quality parameters. The system was run unattended for up to a week at a time in the laboratory and at a small catchment. At the field site, stream-water and precipitation samples were analyzed, alternating at sub-hourly intervals. We observed that measured isotope ratios were highly sensitive to the liquid water flow rate in the CoWS, and thus to the hydraulic head difference between the CoWS and the samples from which water was drawn. We used a programmable high-precision dosing pump to control the injection flow rate and eliminate this flow-rate artifact. Our experiments showed that the precision of the CoWS-L2130-i-system for 2-minute average values was typically better than 0.06‰ for δ18O and 0.16‰ for δ2H. Carryover effects were 1% or less between isotopically contrasting water samples for 30-minute sampling intervals. Instrument drift could be minimized through periodic analysis of

  7. 58W LD side-pump Nd:YAG picosecond laser system at 1KHz with double length of regenerative cavity

    Science.gov (United States)

    Long, Ming Liang; Li, G.; Chen, Meng

    2016-11-01

    An average power of 58 W, pulse width of 40 ps at 1 KHz repetition rate of Nd:YAG picosecond laser is reported. It used an etalon to directly get pulse width of 135 ps from Nd:YVO4 mode locked laser in 1064 nm, which repetition rate was 88 MHz. When the seed pulses were injected into the double length of regenerative LD side-pump Nd:YAG cavity at 1 KHz repetition rate, the single pulse energy was amplified to 3 mJ, the pulse width was compressed to 99 ps, beam quality of M^2 factor was 1.3. The single pulse energy was amplified up to 58 mJ, the pulse width was self compressed to 40 ps, beam quality of M^2 factor was approximately 3.5 after single passing three stages of double high gain LD side-pump Nd:YAG module. Beam pointing was about 40 urad. The stability for pulse to pulse RMS was less than 3%. A thin-film polarizer and a quarter-wave plate was inserted into the regenerative amplification cavity to let pulses double travel the same geometric path basis on pulse polarization. Serrated aperture were used in the amplification. That's beneficial to decrease the nonlinear effect for the high power in the crystal. High gain LD side-pump Nd:YAG module could lead the pulse energy amplify more and self compress the pulse width. Double length of regenerative cavity was used to enhance the optical cavity length, it greatly decreased the laser's volume and improved stability of picosecond laser. It's a nice way for high power picosecond laser and the laser system would be more simple and smaller.

  8. 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.

  9. Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

    Science.gov (United States)

    Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

    2014-02-10

    We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

  10. Continuous Flow - Cavity RingDown Spectroscopy Using a Novel Universal Interface for High-Precision Bulk 13C Analysis

    Science.gov (United States)

    Saad, Nabil; Richman, Bruce

    2010-05-01

    We have developed the world's first optical spectroscopy-based system for bulk stable isotope analysis of 13C. The system is based on a novel universal interface, named LIAISON, capable of coupling to almost any CO2-generating sample preparation front-end ranging from an elemental analyzer to any dissolved carbon analysis module, which are of significant use in geochemical, ecological and food authentication studies. In one specific application, we have coupled LIAISON to an elemental analyzer (EA) and to a cavity ring-down spectrometer (CRDS) for 13C isotopic analysis of adulterated honey samples. Another application was developed to analyze dissolved inorganic carbon in water samples. LIAISON is suited for handling a high-throughput sample analysis process by running three different gas handling operations in parallel: Admitting combustion gas from the EA into a first gas bellows, analyzing the previous sample collected into a second gas bellows with CRDS, and flushing and purging a third gas bellows in preparation for the upcoming sample collection operation. The sample-to-sample analysis time is 10 minutes and the operation is completely automated for the whole front-end auto-sampler tray capacity, requiring no operator intervention. The CRDS data are collected, tabulated and saved into an output text file. The memory effect between the USGS L-Glutamic acid standard at natural abundance and the moderately enriched USGS L-Glutamic acid standard is excluded by the selection of the adequate number and duration of flush and purge cycles of the gas sample bags. The system's proven accuracy was cross-checked with EA-IRMS and its achieved precision was typically less than 0.2 permil, including the 13C-enriched tested samples. The LIAISON-CRDS system presented here provides a fully automated solution for 13C bulk stable isotope analysis with unprecedented ease-of-use and possible field portability and application with the availability of a compact front-end. In

  11. Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS technique

    Directory of Open Access Journals (Sweden)

    H. Chen

    2013-04-01

    Full Text Available Accurate measurements of carbon monoxide (CO in humid air have been made using the cavity ring-down spectroscopy (CRDS technique. The measurements of CO mole fractions are determined from the strength of its spectral absorption in the near-infrared region (~1.57 μm after removing interferences from adjacent carbon dioxide (CO2 and water vapor (H2O absorption lines. Water correction functions that account for the dilution and pressure-broadening effects as well as absorption line interferences from adjacent CO2 and H2O lines have been derived for CO2 mole fractions between 360–390 ppm and for reported H2O mole fractions between 0–4%. The line interference corrections are independent of CO mole fractions. The dependence of the line interference correction on CO2 abundance is estimated to be approximately −0.3 ppb/100 ppm CO2 for dry mole fractions of CO. Comparisons of water correction functions from different analyzers of the same type show significant differences, making it necessary to perform instrument-specific water tests for each individual analyzer. The CRDS analyzer was flown on an aircraft in Alaska from April to November in 2011, and the accuracy of the CO measurements by the CRDS analyzer has been validated against discrete NOAA/ESRL flask sample measurements made on board the same aircraft, with a mean difference between integrated in situ and flask measurements of −0.6 ppb and a standard deviation of 2.8 ppb. Preliminary testing of CRDS instrumentation that employs improved spectroscopic model functions for CO2, H2O, and CO to fit the raw spectral data (available since the beginning of 2012 indicates a smaller water vapor dependence than the models discussed here, but more work is necessary to fully validate the performance. The CRDS technique provides an accurate and low-maintenance method of monitoring the atmospheric dry mole fractions of CO in humid air streams.

  12. High-Power Continuous-Wave Diode-End-Pumped Intracavity Frequency Doubled Nd:YVO4 Laser at 671 nm with a Compact Three-Element Cavity

    Institute of Scientific and Technical Information of China (English)

    ZHOU Rui; DING Xin; WEN Wu-Qi; CAI Zhi-Qiang; WANG Peng; YAO Jian-Quan

    2006-01-01

    @@ We report a high-power high-effcient continuous-wave (cw) diode-end-pumped Nd:YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a compact three-element cavity. At incident pump power of 20.6 W, a maximum output power of 7 W at 1342 nm is obtained with a slope efficiency of 37.3%. By inserting a type-I critical phase-matched LBO crystal as intracavity frequencydoubler, a cw red output as much as 2.85-W is achieved with an incident pump power of 16.9 W, inducing an optical-to-optical conversion efficiency of 16.9%. To the best of our knowledge, this is the highest output of diodepumped solid-state Nd:YVO4 red laser. During half an hour, the red output is very stable, and the instability of output power is less than 1%.

  13. LASERS: Vector model of a ring solid-state laser taking into account the spatial inhomogeneity of the pump and radiation field

    Science.gov (United States)

    Aleshin, D. A.; Kravtsov, Nikolai V.; Lariontsev, E. G.; Chekina, S. N.

    2008-11-01

    A system of equations of the vector model of ring solid-state lasers is derived taking into account the inhomogeneity of the pump transverse distribution and fields of counterpropagating waves. The model under study well describes the experimental dependence of the phase shift of self-modulations oscillations on the pump excess over the threshold. It is shown that the inhomogeneity of the transverse distributions of fields of counterpropagating waves and the inhomogeneity of the permittivity of the intracavity medium can lead to the appearance of frequency and amplitude nonreciprocities in a solid-state laser.

  14. Experience with Dry Running Vacuum Pumps in Helium Service

    Science.gov (United States)

    Arztmann, R.

    2008-03-01

    A process vacuum system for helium using dry running vacuum pumps only was shop tested and installed in a refrigeration plant to serve cavities operating at 2K for a cryogenic storage ring. The paper explains the joint development steps of Busch AG and Linde Kryotechnik AG to use dry running vacuum pumps for helium service at ambient temperature. A roots type booster pump followed by a non lube rotary screw pump provides very good performance in a helium vacuum pump system. Variable frequency drives on both pumps allow to adjust the pump characteristics to a wide range of operating parameters. Operation without friction of sealing elements in the compression space also of the screw pump promises extended maintenance intervals and virtually no wear on the rotors. The current plant operation at Max Plank Institute in Heidelberg, Germany Laboratory will provide additional experience for further applications.

  15. Parametrically Amplified Bright-state Polariton of Four- and Six-wave Mixing in an Optical Ring Cavity

    Science.gov (United States)

    Chen, Haixia; Zhang, Yiqi; Yao, Xin; Wu, Zhenkun; Zhang, Xun; Zhang, Yanpeng; Xiao, Min

    2014-01-01

    We report experimental studies of bright-state polaritons of four-wave mixing (FWM) and six-wave mixing (SWM) signals through cascade nonlinear optical parametric amplification processes in an atom-cavity composite system for the first time. Also, the coexisting cavity transmission modes of parametrically amplified FWM and SWM signals are observed. Finally, electromagnetically induced absorption by the FWM cavity modes in the probe beam is investigated. The investigations can find potential applications in multi-channel narrow-band long-distance quantum communication. PMID:24401795

  16. 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.

  17. 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.

  18. Continuous-wave singly resonant optical parametric oscillator placed inside a ring laser

    DEFF Research Database (Denmark)

    Abitan, Haim; Buchhave, Preben

    2003-01-01

    A cw singly resonant optical parametric oscillator (SRO) was built and placed inside the cavity of a ring laser. The system consists of a diode-end-pumped Nd:YVO4 ring laser with intracavity periodically poled lithium niobate as the nonlinear gain medium of the SRO. When the laser was operated...... the laser was coupled with the SRO. The results show that it is preferable to couple a SRO with a unidirectional ring laser....

  19. Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator.

    Science.gov (United States)

    Cuadrado-Laborde, C; Bello-Jiménez, M; Díez, A; Cruz, J L; Andrés, M V

    2014-01-01

    We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power.

  20. radiofrequency cavity

    CERN Multimedia

    1988-01-01

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  1. Micro-Fluidic Dye Ring Laser - Experimental Tuning of the Wavelength and Numerical Simulation of the Cavity Modes

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Niels Asger

    2006-01-01

    We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view.......We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view....

  2. Hydrogen Isotopic Composition of Arctic and Atmospheric CH4 Determined by a Portable Near-Infrared Cavity Ring-Down Spectrometer with a Cryogenic Pre-Concentrator

    Science.gov (United States)

    Chen, Y.; Lehmann, Kevin K.; Peng, Y.; Pratt, L. M.; White, J. R.; Cadieux, S. B.; Sherwood Lollar, B.; Lacrampe-Couloume, G.; Onstott, T. C.

    2016-10-01

    In this study, near-infrared continuous wave cavity ring-down spectroscopy was applied to the measurement of the δ2H of methane (CH4). The cavity ring-down spectrometer (CRDS) system consisted of multiple DFB laser diodes to optimize selection of spectral line pairs. By rapidly switching measurements between spectral line peaks and the baseline regions, the long-term instrumental drift was minimized, substantially increasing measurement precision. The CRDS system coupled with a cryogenic pre-concentrator measured the δ2H of terrestrial atmospheric CH4 from 3 standard liters of air with a precision of ±1.7‰. The rapidity with which both C and H isotopic measurements of CH4 can be made with the CRDS will enable hourly monitoring of diurnal variations in terrestrial atmospheric CH4 signatures that can be used to increase the resolution of global climate models for the CH4 cycle. Although the current instrument is not capable of measuring the δ2H of 10 ppbv of martian CH4, current technology does exist that could make this feasible for future spaceflight missions. As biological and abiotic CH4 sources have overlapping carbon isotope signatures, dual-element (C and H) analysis is key to reliable differentiation of these sources. Such an instrument package would therefore offer improved ability to determine whether or not the CH4 recently detected in the martian atmosphere is biogenic in origin.

  3. A variable-temperature cavity ring-down spectrometer with application to line shape analysis of CO2 spectra in the 1600 nm region

    Science.gov (United States)

    Ghysels, Mélanie; Liu, Qingnan; Fleisher, Adam J.; Hodges, Joseph T.

    2017-04-01

    We present a new cavity ring-down spectroscopy system which was developed for variable-temperature absorption measurements (220-290 K) of atmospheric gases. This laser spectrometer was developed in the framework of the NASA Orbiting Carbon Observatory-2 project to improve our understanding of line shape parameters for carbon dioxide and oxygen. The apparatus consists of a monolithic, fixed-mirror ring-down cavity within a temperature-regulated enclosure, which is interrogated by a tunable, single-frequency diode laser. We experimentally characterize and model the dependence of the spectrum detuning axis at each setpoint temperature, and show that absolute frequencies are stable to within 200 kHz over several hours, corresponding to temperature stabilities better than 1 mK. We measure the R16e (30013-0001) 12C16O2 transition and carry out multi-spectrum analyses using two line profiles incorporating speed-dependent (quadratic approximation) and Dicke narrowing (hard collision assumption) effects. The resulting broadening coefficient and temperature exponent are in excellent agreement (0.05% level) with previous high-resolution Fourier-transform spectroscopy measurements, and the speed dependent broadening parameter is within 3% of the theoretical value.

  4. Proposal of quantitative measurement of OH radical using planar laser induced fluorescence calibrated by cavity ring-down spectroscopy in turbulent premixed flames

    Science.gov (United States)

    Chen, Shuang; Tu, Xiaobo; Su, Tie; Mu, Jinhe; Yang, Furong

    2017-05-01

    Planar laser induced fluorescence (PLIF) has been a very important species analysis approach in combustion research, but is most often presented qualitatively. Therefore, another supplementary techniques are needed for quantitative PLIF measurement. In this paper, we propose a quantitative OH concentration measurement method using PLIF calibrated by cavity ring-down spectroscopy (CRDS). The CRDS measurement is firstly applied to a methane-air atmospheric pressure flame on a McKenna burner and determine the OH absolute density. Then the PLIF signal is calibrated by the determined OH concentration on the same flame under the same condition. The calibrated PLIF setup is fixed, and another PLIF setup is added to form a two-line OHPLIF thermometry to measure the 2D temperature distribution. Finally, a quantitative OH-PLIF measurement method is provided for the turbulent premixed flame on a Bunsen burner based on this setup.

  5. Carbon isotope analysis of dissolved organic carbon in fresh and saline (NaCl) water via continuous flow cavity ring-down spectroscopy following wet chemical oxidation.

    Science.gov (United States)

    Conaway, Christopher H; Thomas, Burt; Saad, Nabil; Thordsen, James J; Kharaka, Yousif K

    2015-01-01

    This work examines the performance and limitations of a wet chemical oxidation carbon analyser interfaced with a cavity ring-down spectrometer (WCO-CRDS) in a continuous flow (CF) configuration for measuring δ(13)C of dissolved organic carbon (δ(13)C-DOC) in natural water samples. Low-chloride matrix (oxidation despite using high-concentration oxidant, extended reaction time, or post-wet chemical oxidation gas-phase combustion. However, through a combination of dilution, chloride removal, and increasing the oxidant:sample ratio, high-salinity samples with sufficient DOC (>22.5 µg C/aliquot) may be analysed. The WCO-CRDS approach requires more total carbon (µg C/aliquot) than conventional CF-isotope ratio mass spectrometer, but is nonetheless applicable to a wide range of DOC concentration and water types, including brackish water, produced water, and basinal brines.

  6. Comprehensive laboratory and field testing of cavity ring-down spectroscopy analyzers measuring H2O, CO2, CH4 and CO

    Science.gov (United States)

    Yver Kwok, C.; Laurent, O.; Guemri, A.; Philippon, C.; Wastine, B.; Rella, C. W.; Vuillemin, C.; Truong, F.; Delmotte, M.; Kazan, V.; Darding, M.; Lebègue, B.; Kaiser, C.; Xueref-Rémy, I.; Ramonet, M.

    2015-09-01

    To develop an accurate measurement network of greenhouse gases, instruments in the field need to be stable and precise and thus require infrequent calibrations and a low consumption of consumables. For about 10 years, cavity ring-down spectroscopy (CRDS) analyzers have been available that meet these stringent requirements for precision and stability. Here, we present the results of tests of CRDS instruments in the laboratory (47 instruments) and in the field (15 instruments). The precision and stability of the measurements are studied. We demonstrate that, thanks to rigorous testing, newer models generally perform better than older models, especially in terms of reproducibility between instruments. In the field, we see the importance of individual diagnostics during the installation phase, and we show the value of calibration and target gases that assess the quality of the data. Finally, we formulate recommendations for use of these analyzers in the field.

  7. Bulk Stable Isotope Analysis of Carbon from Solids and Liquids using an Elemental Analyzer Coupled to a Wavelength-Scanned Cavity Ring-Down Spectrophotometer

    Science.gov (United States)

    Saad, N.; Rella, C.; van Pelt, A.

    2009-04-01

    We report here on the novel employment of a small footprint Wavelength-Scanned Cavity Ring-Down Spectrometer (WS-CRDS) interfaced to an elemental analyzer for the measurement of the bulk isotopic carbon signature in plants and food products. The current system provides an inexpensive alternative with unparalleled ease-of-use as compared to standard methods using the more complex analytical instrumentation of isotope ratio mass spectrometry. A precision of carbon isotopic ratio measurements of less than 1 permil was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic carbon signatures of a variety of environmental and agricultural products from different origins, providing information about food authenticity and climate changes effect on plant physiology.

  8. Application of Cavity-ring Down Spectroscopy to Quantify NH3 Fluxes from Fertilizer Application in the Midwestern U.S.

    Science.gov (United States)

    Caldwell, J. A.; Sibble, D.; Heuer, M.; Johnson, E.; Rood, M. J.; Koloutsou-Vakakis, S.; Myles, L.

    2014-12-01

    Ammonia (NH3) emissions from managed agriculture in the Midwestern region of the U.S. contribute to increased levels of particulate matter in the atmosphere and detrimental ecological changes. To better understand the exchange of ammonia between the atmosphere and biosphere and identify the drivers of these processes, measurements of NH3 flux were conducted over a 200 m2 fertilized maize field in Illinois. A flux-gradient system paired with a cavity-ring down spectrometer measured fluxes from pre-cultivation through senescence of the crop. The use of a custom automated exchange mechanism allowed for continuous sampling, both above-canopy and in-canopy. Results indicated diurnal cycling of NH3 with higher concentrations in the early afternoon, although the pattern was not consistent. As expected, fertilization of the field at planting produced a marked increase in NH3 emission from the field.

  9. Investigation on 447.3 nm blue-violet laser by extra-cavity frequency doubling of a diode-pumped cesium vapor laser

    Science.gov (United States)

    Xu, Dongdong; Chen, Fei; Guo, Jin; Shao, Mingzhen; Xie, Jijiang

    2016-09-01

    447.3 nm blue-violet lasers are investigated by extra-cavity single-pass second harmonic generation (SHG) of diode-pumped cesium vapor lasers (Cs-DPALs) using a LBO crystal. Two types of 894.6 nm Cs-DPAL are constructed, and the beam quality factors are Mx2=1.02, My2=1.13 and Mx2=2.13, Mx2=2.66, respectively. The maximum output powers for the two types of Cs-DPAL operating in pulsed mode are 0.692 W and 2.6 W, and the corresponding maximum second harmonics (SH) powers are 9.5 μW and 11.2 μW at optimal focusing parameter of 1.68, respectively. The relative insensitivity of SH power to the LBO crystal temperature and the influence of Cs laser beam quality on the SHG efficiency are analyzed qualitatively.

  10. Development of a New N2O/CO Cavity Ring-Down Spectrometer for sub-ppb Ambient Gas Monitoring

    Science.gov (United States)

    Leggett, G. A.; Saad, N.; Zhou, J.; Hoffnagle, J.; Fleck, D.

    2015-12-01

    With a global warming potential of nearly 300, N2O is a critically important greenhouse gas, contributing about 5% of the US total GHG emissions. Agriculture soil management practices are the dominant source of anthropogenic N2O emissions, contributing nearly 3/4ths of US N2O emissions. In urban areas, vehicle tailpipe emissions and waste water treatment plants are significant sources of N2O. We report here a new mid-infrared laser-based cavity ring-down spectrometer that was recently developed to measure sub-ppb ambient concentrations of two key greenhouse gas species, N2O and CO, simultaneously. It combines a quantum cascade laser with a proprietary 3-mirror optical cavity. The new optical analyzer was set up to monitor nitrous oxide and carbon monoxide, along with CO2 and CH4, in ambient air obtained from a 10m tower in Santa Clara, California. In the data collected, the contribution from traffic and a nearby sewage treatment facility was evident.

  11. Second-harmonic generation with ultralow-power pump thresholds in a dimer of two active-passive cavities

    Science.gov (United States)

    Li, Jiahua; Yu, Rong; Qu, Ye; Ding, Chunling; Zhang, Duo; Wu, Ying

    2017-07-01

    One of the current challenges in second-harmonic generation (SHG) is to increase the efficiency of the second-harmonic conversion process while maintaining or even decreasing the fundamental-harmonic pump powers in a compact device. Here, we put forward an on-chip scheme to realize high-efficiency optical SHG in active-passive-coupled microring resonators with the aid of the intrinsic second-order nonlinearity. By careful analysis and extensive simulations, it is found that the introduction of an active microring resonator makes the strong SHG process feature an ultralow-power pump threshold, which is about four orders of magnitude lower than that in a single-microring resonator SHG system reported previously by X. Guo et al. [Optica 3, 1126 (2016), 10.1364/OPTICA.3.001126]. The observed SHG is enhanced by a factor of over 200 compared to the single-microring-resonator SHG system. The SHG conversion efficiency of over 72 % can be reached with optical pump power as low as a few microwatts for our proposed device. This investigation may open a new route towards development of easily fabricated radiation sources of coherent high-energy (shorter-wavelength) photons with an ultralow-power laser-triggered SHG process.

  12. 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.

  13. Compact intra-cavity pumped low-threshold passively Q-switched Ho:Sc2SiO5 laser by a LD-pumped Tm:YAP laser at room temperature

    Science.gov (United States)

    Yang, Xiao-tao; Xie, Wen-qiang; Liu, Long; Li, Lin-jun

    2017-08-01

    A compact intra-cavity pumped low-threshold passively Q-switched (PQS) Ho:Sc2SiO5 (Ho:SSO) laser is reported for the first time. The Tm:YAlO3 (Tm:YAP) crystal and the Ho:SSO crystal are placed in the same laser cavity. A laser diode with a central wavelength of 793 nm is used to realize the output of the Ho:SSO laser. Both the continuous wave (CW) and PQS operation are investigated. A Cr2+:ZnSe is used as the saturable absorber in the PQS Ho:SSO laser. For the CW mode, the laser threshold is only 750 mW, which is 980 mW in the PQS mode. A maximum pulse energy of 699 µJ is primarily obtained, corresponding to the pulse width of 96 ns. The maximum repetition frequency is 1.46 kHz. The maximum pulse peak power can be calculated to be 7.28 kW. The beam quality factor M 2 is calculated to be 1.4 with the maximum output power.

  14. A new cavity ring-down instrument for airborne monitoring of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere

    Science.gov (United States)

    Ruth, Albert A.; Brown, Steven S.; Dinesan, Hemanth; Dubé, William P.; Goulette, Marc; Hübler, Gerhard; Orphal, Johannes; Zahn, Andreas

    2016-04-01

    The chemistry of NO3 and N2O5 is important to the regulation of both tropospheric and stratospheric ozone. In situ detection of NO3 and N2O5 in the upper troposphere lower stratosphere (UTLS) represents a new scientific direction as the only previous measurements of these species in this region of the atmosphere has been via remote sensing techniques. Because both the sources and the sinks for NO3 and N2O5 are potentially stratified spatially, their mixing ratios, and their influence on nitrogen oxide and ozone transport and loss at night can show large variability as a function of altitude. Aircraft-based measurements of heterogeneous N2O5 uptake in the lower troposphere have uncovered a surprising degree of variability in the uptake coefficient [1], but there are no corresponding high altitude measurements.The UTLS is routinely sampled by the IAGOS-CARIBIC program (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container, www.caribic-atmospheric.com), a European infrastructural program with the aim of studying the chemistry and transport across this part of the atmosphere. An airfreight container with 15 different automated instruments from 8 European research partners is utilized on board a commercial Lufthansa airbus 340-600 to monitor ~ 100 atmospheric species (trace gases and aerosol parameters) in the UTLS. The instrumentation in the CARIBIC container is now to be supplemented by a new cavity ring-down device for monitoring nitrogen oxides, jointly developed by researchers from Cork (Ireland), Boulder (USA) and Karlsruhe (Germany). The compact and light-weight instrument is designed to monitor not only NO3 and N2O5, but also NO2 and O3. The detection is based on 4 high-finesse optical cavities (cavity length ~ 44 cm). Two cavities are operated at 662 nm (maximum absorption of NO3), the other two at 405 nm (maximum absorption of NO2). The inlet to one of the (662)-cavities is heated in order to thermally decompose N2O5

  15. Working Principle and Influence Factors of Water Ring Vacuum Pump%水环式真空泵的工作原理及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    马磊; 崔芙红

    2015-01-01

    In many industrial production processes, such as vacuum filter, vacuum degassing, vacuum distillation, vacuum suction, vacuum concentration, vacuum drying, vacuum smelting, water ring pumps are widely used. Through the introduction about the water ring vacuum pump working principle, the way of replenishing for water ring, the application of gas water separator and heat exchanger in saving the water ring liquid flow were introduced, analysis of the affect of working ability about vacuum pumps, such as selecting of the water ring liquid medium, water ring liquid flow rate, the temperature of water ring liquid, and some auxiliary system, was emphasized on. A brief description about vacuum pump faults was given, and some tips when start up or stop a water ring vacuum pump were provided.%在工业生产的许多工艺过程中,如真空过滤、真空脱气、真空蒸馏、真空吸液、真空浓缩、真空干燥、真空冶炼等,水环泵得到广泛的应用。通过对水环式真空泵工作原理的介绍,说明了水环液补水方法,及气水分离器和换热器在水环液流量节约方面的应用,重点分析了影响真空泵工作能力,如水环液介质的选择、水环液流量的大小,水环液的温度,真空辅助系统,最后对真空泵的一些常见故障和启停注意事项作了简单说明。

  16. Ring-Down Spectroscopy for Characterizing a CW Raman Laser

    Science.gov (United States)

    Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

    2007-01-01

    .A relatively simple technique for characterizing an all-resonant intracavity continuous-wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, characterizing signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes. Heretofore, in order to characterize resonant-cavity-based Raman lasers, it has usually been necessary to manipulate the frequencies and power levels of pump lasers and, in each case, to take several sets of measurements. In cases involving ultra-high-Q resonators, it also has been desirable to lock pump lasers to resonator modes to ensure the quality of measurement data. Simpler techniques could be useful. In the present ring-down spectroscopic technique, one infers the parameters of interest from the decay of the laser out of its steady state. This technique does not require changing the power or frequency of the pump laser or locking the pump laser to the resonator mode. The technique is based on a theoretical analysis of what happens when the pump laser is abruptly switched off after the Raman generation reaches the steady state. The analysis starts with differential equations for the evolution of the amplitudes of the pump and Stokes electric fields, leading to solutions for the power levels of the pump and Stokes fields as functions of time and of the aforementioned parameters. Among other things, these solutions show how the ring-down time depends, to some extent, on the electromagnetic energy accumulated in the cavity. The solutions are readily converted to relatively simple equations for the parameters as functions of quantities that can be determined from measurements of the time-dependent power levels. For example, the steady-state intracavity conversion efficiency is given by G1/G2 1 and the threshold power is given by Pin(G2/G1)2, where Pin is the steady-state input pump power immediately prior to

  17. 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

  18. 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%.

  19. An Ultrahigh Precision, High-Frequency Dissolved Inorganic Carbon Analyzer Based on Dual Isotope Dilution and Cavity Ring-Down Spectroscopy.

    Science.gov (United States)

    Huang, Kuan; Cassar, Nicolas; Jonsson, Bror; Cai, Wei-jun; Bender, Michael L

    2015-07-21

    We present a novel method for continuous and automated shipboard measurements of dissolved inorganic carbon concentration ([DIC]) in surface water. The method is based on dual isotope dilution and cavity ring-down spectroscopy (DID-CRDS). In this method, seawater is continuously sampled and mixed with a flow of NaH(13)CO3 solution that is also enriched in deuterated water (the spike). The isotopic composition of CO2 (δ(13)C(spiked_sample)) derived from the DIC in the mixture, and the D/H ratio of the mixed water (δD(spiked_sample)), are measured by CRDS analyzers. The D/H of the water in the mixture allows accurate estimates of the mixing ratio of the sample and the spike. [DIC] of the sample is then calculated from the mixing ratio, [DI(13)C] of the spike, and δ(13)C(spiked_sample). In the laboratory, the precision of the method is test was conducted in the Delaware Bay and Estuary. For 2 min average [DIC], a precision of <0.03% was achieved. Measurements from the DID-CRDS showed good agreement with independent measurements of discrete samples using the well-established coulometric method (mean difference = -1.14 ± 1.68 μmol kg(-1)), and the nondispersive infrared(NDIR)-based methods (mean difference = -0.9 ± 4.73 μmol kg(-1)).

  20. Two-color laser-induced incandescence and cavity ring-down spectroscopy for sensitive and quantitative imaging of soot and PAHs in flames

    Science.gov (United States)

    Schoemaecker Moreau, C.; Therssen, E.; Mercier, X.; Pauwels, J. F.; Desgroux, P.

    Laser-induced incandescence is a technique which enables the measurement of soot volume fractions. However, the laser-induced soot emission might be affected by a fluorescence background generally ascribed to the polycyclic aromatic hydrocarbon compounds (PAHs) present at the soot location. In this paper, spatially resolved distributions of PAH absorbance and soot are obtained in sooting diffusion flames. The original method developed here consists in comparing the emission distributions induced by two different laser wavelengths: (1) at 1064 nm emission signals are exempt from PAH fluorescence and (2) at 532 nm both soot incandescence and PAH emission contribute to the total signal. In addition, the absolute absorption coefficient of the PAH mixture is determined by comparing absorption measurements obtained by cavity ring-down spectroscopy (CRDS) at 1064 nm and 532 nm. The proposed method can provide highly sensitive 2D imaging of PAHs and soot using the fundamental and the second-harmonic frequencies of a single YAG laser. Finally, 2D distributions of PAH absorbance and soot volume fraction calibrated by CRDS are obtained in two diffusion flames, particularly in a very low-sooting flame exhibiting a maximum PAH absorbance of 6×10-4 cm-1 and a maximum soot volume fraction of 3 ppb only. The respective spatial distributions of PAHs and soot are shown to vary with the initial C/O ratio.

  1. Technical note: Coupling infrared gas analysis and cavity ring down spectroscopy for autonomous, high-temporal-resolution measurements of DIC and δ13C-DIC

    Science.gov (United States)

    Call, Mitchell; Schulz, Kai G.; Carvalho, Matheus C.; Santos, Isaac R.; Maher, Damien T.

    2017-03-01

    A new approach to autonomously determine concentrations of dissolved inorganic carbon (DIC) and its carbon stable isotope ratio (δ13C-DIC) at high temporal resolution is presented. The simple method requires no customised design. Instead it uses two commercially available instruments currently used in aquatic carbon research. An inorganic carbon analyser utilising non-dispersive infrared detection (NDIR) is coupled to a Cavity Ring-down Spectrometer (CRDS) to determine DIC and δ13C-DIC based on the liberated CO2 from acidified aliquots of water. Using a small sample volume of 2 mL, the precision and accuracy of the new method was comparable to standard isotope ratio mass spectrometry (IRMS) methods. The system achieved a sampling resolution of 16 min, with a DIC precision of ±1.5 to 2 µmol kg-1 and δ13C-DIC precision of ±0.14 ‰ for concentrations spanning 1000 to 3600 µmol kg-1. Accuracy of 0.1 ± 0.06 ‰ for δ13C-DIC based on DIC concentrations ranging from 2000 to 2230 µmol kg-1 was achieved during a laboratory-based algal bloom experiment. The high precision data that can be autonomously obtained by the system should enable complex carbonate system questions to be explored in aquatic sciences using high-temporal-resolution observations.

  2. Generation of a Sub-10 fs Laser Pulse by a Ring Oscillator with a High Repetition Rate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing; ZHAO Yan-Ying; WEI Zhi-Yi

    2009-01-01

    @@ A compact femtoescond Ti:sapphire ring oscillator composed of chirped mirrors is designed. By accurately optimizing the intra-cavity dispersion and the mode locking range of the ring configuration, we generate laser pulses as short as 7.7 fs with a repetition rate as high as 745 MHz. The spectrum spans from 660nm to 940nm and the average output power is 480row under the cw pump laser of 7.5 W.

  3. First Continuous High Frequency in Situ Measurements of CO2 and CH4 in Rwanda Using Cavity Ring-down Spectroscopy

    Science.gov (United States)

    Gasore, J.; DeWitt, L. H.; Prinn, R. G.

    2015-12-01

    Recent IPCC reports emphasize the lack of ground measurements of greenhouse gases on the African continent, despite Africa's significant emissions from agriculture and biomass burning as well as ongoing land use changes. We have established a greenhouse gas monitoring station in northern Rwanda that will be part of the Advanced Global Atmospheric Gases Experiment (AGAGE), a global network of high frequency long-term remote atmospheric measurement stations. Using a Picarro G2401 cavity ring-down analyzer, continuous measurements of CO2, CH4, and CO at a frequency of five seconds are being captured at this equatorial East African site. The measurement site is located near the Virunga mountains, a volcanic range in North-West Rwanda, on the summit of Mt. Mugogo (2507 m above sea level). Mt. Mugogo is located in a rural area 70km away from Kigali, the capital of Rwanda, and about 13km from the nearest town. From HYSPLIT 7-day back-trajectory calculations, we have determined that the station measures air masses originating from East and Central Africa, the Indian Ocean and occasionally from Southern Asia. Depending on the wind direction and local boundary layer height, measurements taken at Mt Mugogo are occasionally influenced by local sources, including emissions from the nearby city and wood fires from small rural settlements around the station. Here we present the first greenhouse gas measurement data from this unique and understudied location in Africa. Using the lagrangian transport and dispersion model FLEXPART, we derive the relationship between the observed mole fractions of CO2 and CH4 and our current knowledge of their sources and sinks, across this large African footprint.

  4. 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.

  5. A conjugated mess: measurements of benzene (C6H6), CH4, CO2, and H2O using a cavity ring-down spectrometer

    Science.gov (United States)

    Fleck, Derek; Hoffnagle, John; He, Yonggang

    2017-04-01

    Benzene is widely used carcinogenic chemical that ranks among the top 15 chemicals produced in the world by volume. It is part of many industrial processes from solvents to rubber and drug production and is also produced in petroleum refinement and use. OSHA and European regulators have set a strict long-term exposure limit and short-term exposure limit of 1ppm and 15ppm, respectively, to minimize hazards to a person's health. With the recent passing by the EPA of mandatory fence line monitoring of benzene at petroleum factories, it is evident that a robust, continuous measurement of benzene is necessary. Conventional measurements of benzene suffer from a high granularity (nearly 1 ppm), cumbersome sample preparation/processing, or cross-sensitivities from other gas species. The aim of this study is to show development of an analyzer using cavity ring-down spectrometry (CRDS) to measure benzene, as well as all the main constituents of air that can influence a measurement: H2O, CO2, and CH4. A measurement of benzene to an uncertainty of 100 ppb in <5 minutes is currently attainable, with a future goal of making this measurement in only ten seconds to 1 minute. Initial results show precisions of CH4 at 0.5ppb, CO2 at 0.5ppm and H2O of 10ppm. Because of the relatively IR-inactive C6H6 molecule, only broad features lying underneath the relatively sharp signals of CH4, CO2, and H2O can be used to quantify benzene concentrations. The stability of the CRDS analyzer allows us to look at structured changes in the baseline due to benzene to get out a precise measurement, while rarely having to do a zero-reference calibration. The analysis of these four species yields an instrument that is not only viable for fence line monitoring of petroleum refineries, but one that could also be used for local atmospheric monitoring of cities or even gas-stations.

  6. The near infrared spectrum of ozone by CW-cavity ring down spectroscopy between 5850 and 7000 cm(-1): new observations and exhaustive review.

    Science.gov (United States)

    Campargue, A; Barbe, A; De Backer-Barilly, M-R; Tyuterev, Vl G; Kassi, S

    2008-05-28

    Weak vibrational bands of (16)O(3) could be detected in the 5850-7030 cm(-1) spectral region by CW-cavity ring down spectroscopy using a set of fibered DFB diode lasers. As a result of the high sensitivity (noise equivalent absorption alpha(min) approximately 3 x 10(-10) cm(-1)), bands reaching a total of 16 upper vibrational states have been previously reported in selected spectral regions. In the present report, the analysis of the whole investigated region is completed by new recordings in three spectral regions which have allowed: (i) a refined analysis of the nu(1) + 3nu(2) + 3nu(3) band from new spectra in the 5850-5900 cm(-1) region; (ii) an important extension of the assignments of the 2nu(1)+5nu(3) and 4nu(1) + 2nu(2) + nu(3) bands in the 6500-6600 cm(-1) region, previously recorded by frequency modulation diode laser spectroscopy. The rovibrational assignments of the weak 4nu(1) + 2nu(2) + nu(3) band were fully confirmed by the new observation of the 4nu(1) + 2nu(2) + nu(3)- nu(2) hot band near 5866.9 cm(-1) reaching the same upper state; (iii) the observation and modelling of three A-type bands at 6895.51, 6981.87 and 6990.07 cm(-1) corresponding to the highest excited vibrational bands of ozone detected so far at high resolution. The upper vibrational states were assigned by comparison of their energy values with calculated values obtained from the ground state potential energy surface of (16)O(3). The vibrational mixing and consequently the ambiguities in the vibrational labelling are discussed. For each band or set of interacting bands, the spectroscopic parameters were determined from a fit of the corresponding line positions in the frame of the effective Hamiltonian (EH) model. A set of selected absolute line intensities was measured and used to derive the parameters of the effective transition moment operator. The exhaustive review of the previous observations gathered with the present results is presented and discussed. It leads to a total number

  7. Diode laser-based cavity ring-down instrument for NO3, N2O5, NO, NO2 and O3 from aircraft

    Directory of Open Access Journals (Sweden)

    T. B. Ryerson

    2011-03-01

    Full Text Available This article presents a diode laser based, cavity ring-down spectrometer for simultaneous in situ measurements of four nitrogen oxide species, NO3, N2O5, NO, NO2, as well as O3, designed for deployment on aircraft. The instrument measures NO3 and NO2 by optical extinction at 662 nm and 405 nm, respectively; N2O5 is measured by thermal conversion to NO3, while NO and O3 are measured by chemical conversion to NO2. The instrument has several advantages over previous instruments developed by our group for measurement of NO2, NO3 and N2O5 alone, based on a pulsed Nd:YAG and dye laser. First, the use of continuous wave diode lasers reduces the requirements for power and weight and eliminates hazardous materials. Second, detection of NO2 at 405 nm is more sensitive than our previously reported 532 nm instrument, and does not have a measurable interference from O3. Third, the instrument includes chemical conversion of NO and O3 to NO2 to provide measurements of total NOx (= NO + NO2 and Ox (= NO2 + O3 on two separate channels; mixing ratios of NO and O3 are determined by subtraction of NO2. Finally, all five species are calibrated against a single standard based on 254 nm O3 absorption to provide high accuracy. Disadvantages include an increased sensitivity to water vapor on the 662 nm NO3 and N2O5 channels and a modest reduction in sensitivity for these species compared to the pulsed laser instrument. The measurement precision for both NO3 and N2O5 is below 1 pptv (2σ, 1 s and for NO, NO2 and O3 is 170, 46, and 56 pptv (2σ, 1 s respectively. The NO and NO2 measurements are less precise than research-grade chemiluminescence instruments. However, the combination of these five species in a single instrument, calibrated to a single analytical standard, provides a complete and accurate picture of nighttime nitrogen oxide chemistry. The instrument performance is demonstrated using data acquired during a recent field campaign in California.

  8. Diode laser-based cavity ring-down instrument for NO3, N2O5, NO, NO2 and O3 from aircraft

    Directory of Open Access Journals (Sweden)

    T. B. Ryerson

    2011-06-01

    Full Text Available This article presents a diode laser-based, cavity ring-down spectrometer for simultaneous in situ measurements of four nitrogen oxide species, NO3, N2O5, NO, NO2, as well as O3, designed for deployment on aircraft. The instrument measures NO3 and NO2 by optical extinction at 662 nm and 405 nm, respectively; N2O5 is measured by thermal conversion to NO3, while NO and O3 are measured by chemical conversion to NO2. The instrument has several advantages over previous instruments developed by our group for measurement of NO2, NO3 and N2O5 alone, based on a pulsed Nd:YAG and dye laser. First, the use of continuous wave diode lasers reduces the requirements for power and weight and eliminates hazardous materials. Second, detection of NO2 at 405 nm is more sensitive than our previously reported 532 nm instrument, and does not have a measurable interference from O3. Third, the instrument includes chemical conversion of NO and O3 to NO2 to provide measurements of total NOx (= NO + NO2 and Ox (= NO2 + O3 on two separate channels; mixing ratios of NO and O3 are determined by subtraction of NO2. Finally, all five species are calibrated against a single standard based on 254 nm O3 absorption to provide high accuracy. Disadvantages include an increased sensitivity to water vapor on the 662 nm NO3 and N2O5 channels and a modest reduction in sensitivity for these species compared to the pulsed laser instrument. The in-flight detection limit for both NO3 and N2O5 is 3 pptv (2 σ, 1 s and for NO, NO2 and O3 is 140, 90, and 120 pptv (2 σ, 1 s respectively. Demonstrated performance of the instrument in a laboratory/ground based environment is better by approximately a factor of 2–3. The NO and NO2 measurements are less precise than research-grade chemiluminescence instruments. However, the combination of these five species in a single instrument, calibrated to a single analytical standard, provides a complete and accurate picture of nighttime nitrogen oxide

  9. Cavity Ring-Down Spectroscopy of Hydrogen in the 784-852 NM Region and Corresponding Line Shape Implementation Into HITRAN

    Science.gov (United States)

    Tan, Yan; Wang, Jin; Cheng, Cunfeng; Liu, An-Wen; Hu, Shui-Ming; Wcislo, Piotr; Kochanov, Roman V.; Gordon, Iouli E.; Rothman, Laurence S.

    2016-06-01

    The hydrogen molecule as the most abundant neutral molecule in the universe is an important object of studies in different areas of science, especially astrophysics. The precision spectroscopy of the hydrogen molecule is particularly useful to verify the quantum electrodynamics theory (QED) in a molecular system. The electric quadrupole transitions of the second overtone of H_2 have been recorded with a high precision cavity ring-down spectrometer. A total of eight lines including the extremely weak S3(5) line in the 784-852 nm range have been observed. The line positions have been determined to an accuracy of 3 × 10-4 cm-1 and the line intensities were determined with a relative accuracy of about 1%. The deviations between the experimental and theoretical frequencies are less than 5 × 10-4 cm-1, which is much smaller than the claimed theoretical uncertainty of 0.0025cm-1. The data from this experiment along with other high-quality H_2 spectra have also been analyzed by the Hartmann-Tran profile as a test case for incorporating parametrization of this profile in the HITRAN database. It was incorporated in the new relational structure of the HITRAN database (www.hitran.org) and into the HITRAN Application Programming Interface (HAPI) for the case of H_2 spectra. Tan Y, Wang J, Cheng C-F, Zhao X-Q, Liu A-W, Hu S-M, J Mol Spectrosc 2014;300:60-4; Tran H, Ngo NH, Hartmann J-M, J Quant Spectrosc Radiat Transf 2013;129:199-203; Wcislo P, Gordon IE, Tran H, Tan Y, Hu S-M, Campargue A, et al., Accepted J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015 Rothman LS, Gordon IE, Babikov Y, Barbe A, Chris Benner D, Bernath PF, et al., J Quant Spectrosc Radiat Transf 2013;130:4-50; Kochanov RV, Gordon IE, Rothman LS, Wcislo P, Hill C, Wilzewski JS, Submitted to J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015.

  10. High Resolution Infrared Spectra of Plasma Jet-Cooled - and Triacetylene in the C-H Stretch Region by CW Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Zhao, D.; Guss, J.; Walsh, A.; Doney, K.; Linnartz, H.

    2013-06-01

    Polyacetylenes form an important series of unsaturated hydrocarbons that are of astrophysical interest. Small polyacetylenes have been detected from infrared observations in dense atmosphere of Titan and in a protoplanetary nebula CRL 618. We present here high-resolution mid-infrared spectra of diacetylene (HC_{4}H) and triacetylene (HC_{6}H) that are recorded in a supersonically expanded pulsed planar plasma using an ultra-sensitive detection technique. This method uses an all fiber-laser-based optical parametric oscillator (OPO), in combination with continuous wave cavity ring-down spectroscopy (cw-CRDS) as a direct absorption detection tool. A hardware-based multi-trigger concept is developed to apply cw-CRDS to pulsed plasmas. Vibrationally hot but rotationally cold HC_{4}H and HC_{6}H are produced by discharging a C_{2}H_{2}/He/Ar gas mixture which is supersonically expanded into a vacuum chamber through a slit discharge nozzle. Experimental spectra are recorded at a resolution of ˜100 MHz in the 3305-3340 cm^{-1} region, which is characteristic of the C-H stretch vibrations of HC_{4}H and HC_{6}H. Jet-cooling in our experiment reduces the rotational temperature of both HC_{4}H and HC_{6}H to <20 K. In total, ˜2000 lines are measured. More than fourteen (vibrationally hot) bands for HC_{4}H and four bands for HC_{6}H are assigned based on Loomis-Wood diagrams, and nearly half of these bands are analyzed for the first time. For both molecules improved and new molecular constants of a series of vibrational levels are presented. The accurate molecular data reported here, particularly those for low-lying (bending) vibrational levels may be used to interpret the ro-vibrational transitions in the FIR and submillimeter/THz region. D. Zhao, J. Guss, A. Walsh, H. Linnartz Chem. Phys. Lett., {dx.doi.org/10.1016/j.cplett.2013.02.025}, in press, 2013.

  11. In-Situ Measurements of Aerosol Optical Properties using New Cavity Ring-Down and Photoacoustics Instruments and Comparison with more Traditional Techniques

    Science.gov (United States)

    Strawa, A. W.; Arnott, P.; Covert, D.; Elleman, R.; Ferrare, R.; Hallar, A. G.; Jonsson, H.; Kirchstetter, T. W.; Luu, A. P.; Ogren, J.

    2004-01-01

    Carbonaceous species (BC and OC) are responsible for most of the absorption associated with aerosol particles. The amount of radiant energy an aerosol absorbs has profound effects on climate and air quality. It is ironic that aerosol absorption coefficient is one of the most difficult aerosol properties to measure. A new cavity ring-down (CRD) instrument, called Cadenza (NASA-ARC), measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. Absorption coefficient is obtained from the difference of measured extinction and scattering within the instrument. Aerosol absorption coefficient is also measured by a photoacoustic (PA) instrument (DRI) that was operated on an aircraft for the first time during the DOE Aerosol Intensive Operating Period (IOP). This paper will report on measurements made with this new instrument and other in-situ instruments during two field recent field studies. The first field study was an airborne cam;oaign, the DOE Aerosol Intensive Operating Period flown in May, 2003 over northern Oklahoma. One of the main purposes of the IOP was to assess our ability to measure extinction and absorption coefficient in situ. This paper compares measurements of these aerosol optical properties made by the CRD, PA, nephelometer, and Particle Soot Absorption Photometer (PSAP) aboard the CIRPAS Twin-Otter. During the IOP, several significant aerosol layers were sampled aloft. These layers are identified in the remote (AATS-14) as well as in situ measurements. Extinction profiles measured by Cadenza are compared to those derived from the Ames Airborne Tracking Sunphotometer (AATS-14, NASA-ARC). The regional radiative impact of these layers is assessed by using the measured aerosol optical properties in a radiative transfer model. The second study was conducted in the Caldecott Tunnel, a heavily-used tunnel located north of San Francisco, Ca. The aerosol sampled in this study was

  12. Monolithic optofluidic ring resonator lasers created by femtosecond laser nanofabrication.

    Science.gov (United States)

    Chandrahalim, Hengky; Chen, Qiushu; Said, Ali A; Dugan, Mark; Fan, Xudong

    2015-05-21

    We designed, fabricated, and characterized a monolithically integrated optofluidic ring resonator laser that is mechanically, thermally, and chemically robust. The entire device, including the ring resonator channel and sample delivery microfluidics, was created in a block of fused-silica glass using a 3-dimensional femtosecond laser writing process. The gain medium, composed of Rhodamine 6G (R6G) dissolved in quinoline, was flowed through the ring resonator. Lasing was achieved at a pump threshold of approximately 15 μJ mm(-2). Detailed analysis shows that the Q-factor of the optofluidic ring resonator is 3.3 × 10(4), which is limited by both solvent absorption and scattering loss. In particular, a Q-factor resulting from the scattering loss can be as high as 4.2 × 10(4), suggesting the feasibility of using a femtosecond laser to create high quality optical cavities.

  13. High-Power Red Light Generation by Intra-Cavity Frequency-Doubling of a Side-Pumped Nd:YAG Laser in a LiB.3O5 Crystal

    Institute of Scientific and Technical Information of China (English)

    SUN Zhi-Pei; ZHANG Hong-Bo; CUI Da-Fu; XU Zu-Yan; LI Rui-Ning; BI Yong; YANG Xiao-Dong; BO Yong; HOU Wei; ZHANG Ying; WANG Gui-Ling; ZHAO Wu-Li

    2004-01-01

    We report the generation of high-power red light radiation of 11.2 W in a LiB3O5(LBO) crystal with intra-cavity frequency doubling of two compact and simple side-pumped Nd:YAG laser modules under a repetition rate of 3.5kHz. The pulse width of output is about 180 ± 20ns. The beam quality of the M2 value is 15 ± 3 in both the directions. This excellent laser performance demonstrates that the Nd:YAG laser with LBO intracavity frequency doubling is an promising method for generating red light with high brightness.

  14. JLEIC SRF cavity RF Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Guo, Jiquan [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The initial design of a low higher order modes (HOM) impedance superconducting RF (SRF) cavity is presented in this paper. The design of this SRF cavity is for the proposed Jefferson Lab Electron Ion Collider (JLEIC). The electron ring of JLEIC will operate with electrons of 3 to 10 GeV energy. The ion ring of JLEIC will operate with protons of up to 100 GeV energy. The bunch lengths in both rings are ~12 mm (RMS). In order to maintain the short bunch length in the ion ring, SRF cavities are adopted to provide large enough gradient. In the first phase of JLEIC, the PEP II RF cavities will be reused in the electron ring to lower the initial cost. The frequency of the SRF cavities is chosen to be the second harmonic of PEP II cavities, 952.6 MHz. In the second phase of JLEIC, the same frequency SRF cavities may replace the normal conducting PEP II cavities to achieve higher luminosity at high energy. At low energies, the synchro-tron radiation damping effect is quite weak, to avoid the coupled bunch instability caused by the intense closely-spaced electron bunches, low HOM impedance of the SRF cavities combined with longitudinal feedback sys-tem will be necessary.

  15. Performance analysis of progressive cavity pumps in oil wells with high BSW (Basic Sediment Water); Analise do desempenho de elastometros do bombeio de cavidades progressivas em pocos de petroleo com elavado BSW (Basic Sediment Water)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Cindi Alves; Santos, Joao Paulo Lobo dos; Lobato, Ana Katerine de Carvalho Lima; Santos, Luiz Carlos Lobato dos [Universidade Federal da Bahia, BA (Brazil); Duarte, Lindemberg de Jesus Nogueira [Universidade Federal do Rio Grande do Norte, RN (Brazil)

    2012-07-01

    One of the most important equipment in the progressing cavity pump (PCP) is the subsurface pump, which comprises a rotor and a stator covered internally by an elastomer. This is responsible for sealing the pump and, consequently, for elevating the fluids. In fact, this polymer is used because of the ability to generate pressure in the pump by the seals formed between the cavities. In order to guarantee that the elastomer will have a good performance in the PCP system certain requirements need to be checked, such as: stress, elongation, hardness, resilience, permeability and adhesion. The fluids and solids handled by the PCP system, allied to high temperatures can cause premature wear in the elastomers. The most common reactions which are also observed in most of the wells are swelling, shrinkage, softening, hardening and explosive decompression. In this sense, the aim of this work is to study some elastomers which were chosen based on compatibility tests conducted by a major oil company. The problems that occurred in the wells will be analyzed in order to verify whether the choice of the elastomer had some influence on system failure. For this purpose, the intervention reports, efficiency tests and failure analysis reports will be used. At the end of this work, it was possible to diagnose the causes, consequences and solutions to inherent problems at various oil wells in a field that is in an advanced stage of recovery. Finally, it was concluded that simple changes in the process of compatibility analysis would help to increase the reliability level of the tests, especially the problems observed during the PCP operation in hostile environments. (author)

  16. Design and Operation of a Supersonic Flow Cavity for a Non-Self-Sustained Electric Discharge Pumped Oxygen-Iodine Laser

    Science.gov (United States)

    2007-02-16

    static pressure taps are shown along the bottom cavity wall. OMA V camera. The emission signal was collected using a Thor Labs 1 m long fibre optic bundle...in the supersonic cavity wall), and the opposite end of the fibre optic bundle was placed in front of the spectrometer slit. The use of the fibre ... optic link greatly improved the alignment of the optical diagnostics system. The O2(a 1) concentration in the discharge afterglow and the SDO yield were

  17. Computational Method for Thermal-Mechanical Coupling of Progressing Cavity Pump%螺杆泵定子热力耦合的计算方法研究

    Institute of Scientific and Technical Information of China (English)

    操建平; 孟庆昆; 高圣平; 王向东; 胡贵

    2012-01-01

    Temperature is the important factor influencing the workability of downhole progressing cavity pump (PCP), high temperatures will reduce its performance and service life. On the other hand, high temperature can cause expansion of rubber, and increase the working torque. A calculation model for heat generation of PCP is proposed. The strain and stress of the rubber are obtained using the finite element method at first, then Fourier series is utilized to fit the stress and the strain of rubber in the rolling process, heat generation can be calculated according to this model,the temperature research model of the PCP is set up. Meanwhile, the conventional PCP is contrasted with uniform-thickness PCP, the highest temperature of conventional PCP and uniform-thickness PCP are both at the center of the area where the straight part of contour line is, but temperature distribution of uniform-thickness PCP is more uniform) The maximum temperature rise is proportional to the rotational speed; The uniform-thickness PCP allows higher speed than conventional PCP under the same conditions, this conclusion indicates that uniform-thickness PCP has more advantages than conventional PCP in the field that the range of flow is wide (for example, Drainage Gas Recovery in CBM well).%温度是井下螺杆泵的工作性能的重要影响因素,过高的温度会降低其性能,减少泵的使用寿命,高温还会导致橡胶衬套的膨胀,增大螺杆泵运行时的扭矩.提出了一种橡胶生热计算模型:首先得到螺杆泵橡胶的应力应变,然后利用傅里叶级数拟合其应力应变,通过生热模型计算橡胶的生热率,最后建立了螺杆泵定子橡胶的温度场分析模型.常规螺杆泵和等壁厚螺杆泵的最高温度都在直线段橡胶衬套中点处,但等壁厚螺杆泵的温度分布更加均匀;转速对于螺杆泵定子橡胶衬套的最大温升的影响是成正比的;相同条件下,仅仅考虑橡胶衬套的许可的温度,等壁厚

  18. 螺杆泵采油系统杆柱的扭转振动特性分析%The twisting vibration characteristic analysis of the sucker rod string for progressing cavity pump oil production system

    Institute of Scientific and Technical Information of China (English)

    彭勇

    2001-01-01

    对直井中用于驱动井下螺杆泵的旋转级次抽油杆柱建立了扭转振动分析模型,推导出了该级次抽油杆柱扭转振动频率的计算公式,建立了级次杆柱扭振固有基频与单级杆柱固有基频之间的关系。计算表明,泵深在700~1800m时,常用的二级抽油杆柱组合的扭振固有基频为22~58r/min,低于螺杆泵的工作转速区,这完全不同于有杆泵抽油系统。指出,由于螺杆泵采油系统的工作转速区高于其杆柱扭振固有基频,在选定螺杆泵采油系统的工作转速时,除考虑杆柱的基频外,还应考虑杆柱的扭振高次谐波频率,这样可以避免系统工作在高次谐波共振区,而且有利于避免系统工作转速在穿越高次谐波对应的转速时系统的失速;在设计螺杆泵采油系统杆柱组合时,应考虑组合杆柱对杆柱扭振基频的提高,尤其要注意常用的二级杆柱组合时杆长比接近50%的情况。%In this paper it makes a twisting vibration analysis model of therotary sucker rod string,which is used to drive the progressing cavity pump in vertical well,and deduces the calculating formula of the sucker rod string's twisting vibration frequency.then sets up a relation between sucker rod string's twisting vibration natural base frequency and single sucker rod's natural frequency.According to the calculation,the twisting vibration base frequency of common two-staged sucker rod string is from 20~58 rpm when pump is working within the depth of 700~1 800 m,which is below the working speed of progressing cavity pump,and it is completely different from the sucker rod pump oil production system.The paper points out that because the working speed of progressing cavity pump oil production system is higher than the twisting vibration base frequency of its sucker rod string,when we choose the working speed of the system,it is necessary to consider the base frequency as well as the high harmonic

  19. Cavity-enhanced spectroscopies

    CERN Document Server

    van Zee, Roger

    2003-01-01

    ""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

  20. Single and Coupled Nanobeam Cavities

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.

    2013-01-01

    for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...

  1. 抽运调制条件下超窄线宽掺铒光纤环形激光器的跳模特性研究%Investigation on Characteristics of Mode Hopping in Ultra-Narrow Linewidth Erbium-Doped Fiber Ring Laser under Pump Modulation

    Institute of Scientific and Technical Information of China (English)

    马明祥; 杨华勇; 徐攀; 胡正良; 胡永明

    2012-01-01

    One type of mode-hopping detection system based on fiber Michelson interferometer is set up. The influence of pump modulation on the mode-hopping characteristics of ultra-narrow linewidth erbium-doped fiber ring laser is investigated experimentally through the system. The mode-hopping map of laser labeled by pump current is measured to reveal the mode-hopping characteristics. Numerical results show that the laser will orderly experience steady single-mode area, unsteady single-mode area and multimode area with the pump current increasing, and there exists a second threshold over which the laser will hop from single-mode into drastic multimode. Besides, frequency drift going with serial mode hops can be excited by pump-induced thermal effect or hostile disturbances applied on the laser cavity.%搭建了基于光纤迈克耳孙干涉仪的跳模检测系统,对抽运调制条件下的超窄线宽掺铒光纤环形激光器的跳模特性进行了实验研究,测量了由抽运电流标定的表征跳模规律的跳模数据图.结果表明,随着抽运电流的不断增加,激光器先后经历模式稳定区、模式非稳区以及多纵模区三种状态;存在第二抽运阈值,当抽运强度超过这一阈值时激光器由单纵模跳变为非稳定的多纵模.掺铒光纤环形激光器的谐振腔因抽运热效应或外界扰动而变化时,会引发频率漂移与连续跳模现象.

  2. Tailoring the negative-refractive-index metamaterials composed of semiconductor-metal-semiconductor gold ring/disk cavity heptamers to support strong Fano resonances in the visible spectrum.

    Science.gov (United States)

    Ahmadivand, Arash; Pala, Nezih

    2015-02-01

    In this study, we investigated numerically the plasmon response of a planar negative-index metamaterial composed of symmetric molecular orientations of Au ring/disk nanocavities in a heptamer cluster. Using the plasmon hybridization theory and considering the optical response of an individual nanocluster, we determined the accurate geometrical sizes for a ring/disk nanocavity heptamer. It is shown that the proposed well-organized nanocluster can be tailored to support strong and sharp Fano resonances in the visible spectrum. Surrounding and filling the heptamer clusters by various metasurfaces with different chemical characteristics, and illuminating the structure with an incident light source, we proved that this configuration reflects low losses and isotropic features, including a pronounced Fano dip in the visible spectrum. Technically, employing numerical methods and tuning the geometrical sizes of the structure, we tuned and induced the Fano dip in the visible range, while the dark and bright plasmon resonance extremes are blueshifted to shorter wavelengths dramatically. Considering the calculated transmission window, we quantified the effective refractive index for the structure, while the substance of the substrate material was varied. Using Si, GaP, and InP semiconductors as substrate materials, we calculated and compared the corresponding figure of merit (FOM) for different regimes. The highest possible FOM was obtained for the GaP-Au-GaP negative-refractive-index metamaterial composed of ring/disk nanocavity heptamers as 62.4 at λ∼690  nm (arounnd the position of the Fano dip). Despite the outstanding symmetric nature of the suggested heptamer array, we provided sharp Fano dips by the appropriate tuning of the geometrical and chemical parameters. This study yields a method to employ ring/disk nanocavity heptamers as a negative-refractive-index metamaterial in designing highly accurate localization of surface plasmon resonance sensing devices and

  3. Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

    Science.gov (United States)

    Azzini, Stefano; Grassani, Davide; Galli, Matteo; Gerace, Dario; Patrini, Maddalena; Liscidini, Marco; Velha, Philippe; Bajoni, Daniele

    2013-07-01

    We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitude. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators.

  4. Characterisation and first application of a cavity ring-down instrument for measurements of NO3 and N2O5

    Science.gov (United States)

    Schrade, Stephanie; Bachner, Mathias; Kubik, Kamil; Fuchs, Hendrik

    2014-05-01

    A new instrument was built for atmospheric measurements using the cavity ringdown technique for a simultaneous measurement of nitrate radicals (NO3) and dinitrogen pentoxide (N2O5) using a red laser diode at 662 nm. The instrument consists of two channels: The inlet and the cavity of the first one is heated up to 120 °C to force the thermal equlibrium of N2O5 and NO3 to the side of NO3, so that this channel measures the sum NO3 and N2O5. The other channel stays at ambient temperature to measure NO3 only. To prevent aerosol extinction, a filter is installed upstream of the cavities. The detection limit is within the range of a few ppt at 1 s time resolution. Measurements have an accuracy of 15 %. Instrument losses were characterized by a titration method using the conversion of NO3 to NO2 by adding NO. Two addition points where chosen, right before and after the NO3 intrument.The NO2 concentration was measured downstream of the instrument with another CRDS intrument using a blue laser diode at 405 nm. Estimated losses are within the range of 40 % due two a high point loss on the used filter housing. First application took place at the SAPHIR simulation chamber at Forschungszentrum Jülich GmbH. Experiments were made by injecting known concentrations of NO2 and ozone into the dark chamber filled with pure synthetic air to analyse the behavior of NO3 and N2O5 in the clean chamber. Possible losses were estimated from the steady-state lifetime of NO3, which can be calculated from measured NO3, NO2 and ozone concentrations. Estimated lifetimes of NO3 and N2O5 were within the range of 19 min and 44 min, respetively. During futher experiments organic compounds (isoprene, β-pinene, limonene) were additionally injected, in order to test the applicability of chamber experiments for the invertigation of oxidation processes by NO3.

  5. Prototype storage cavity for LEP accelerating RF

    CERN Multimedia

    1980-01-01

    The principle of an RF storage cavity was demonstrated with this prototype, working at 500 MHz. Ian Wilso seems to hold it in his hands. The storage cavities had 4 portholes, 1 each for: RF feed; tuning; connection to the accelerating cavity; vacuum pump. The final storage cavities were larger, to suit the lower LEP accelerating frequency of 352.2 MHz. See also 8002294, 8006510X, 8109346, 8407619X, and Annual Report 1980, p.115.

  6. Design and Analysis of Dumbbell-shaped Seal Ring of Hydraulic Oil Pumping System%液压抽油系统哑铃型密封圈设计与分析

    Institute of Scientific and Technical Information of China (English)

    朱拾东; 张建军; 刘猛; 师峻峰; 赵瑞东

    2013-01-01

    In the hydraulic oil pumping system with water as power fluid,the conventional O-ring and other sealing rings cannot meet the sealing requirements of not collusion for high and low pressure fluid. A new type of dumbbell-shaped seal ring was designed and its sealing mechanism was analyzed. The contact deformation and the contact stress distribution on the contact sealing interface under the action of the liquid pressure were analyzed by finite element analysis software. The results show that the designed dumbbell-shaped sealing structure can meet the sealing requirements of 16 MPa differential pressure of the hydraulic oil pumping system.%  在以水作为动力液介质的液压抽油系统中,常规的O型密封圈及其他密封圈都不能满足高、低压流体之间不串通的密封要求。设计了一种新型的哑铃型密封结构,并分析其密封机制;利用有限元软件分析在液体压力作用下密封圈的接触变形、接触密封界面上的接触应力分布。结果表明,设计的哑铃型密封结构可以满足要求液压抽油系统16 MPa压差的密封要求。

  7. Nanobeam photonic crystal cavity quantum dot laser

    CERN Document Server

    Gong, Yiyang; Shambat, Gary; Sarmiento, Tomas; Harris, James S; Vuckovic, Jelena

    2010-01-01

    The lasing behavior of one dimensional GaAs nanobeam cavities with embedded InAs quantum dots is studied at room temperature. Lasing is observed throughout the quantum dot PL spectrum, and the wavelength dependence of the threshold is calculated. We study the cavity lasers under both 780 nm and 980 nm pump, finding thresholds as low as 0.3 uW and 19 uW for the two pump wavelengths, respectively. Finally, the nanobeam cavity laser wavelengths are tuned by up to 7 nm by employing a fiber taper in near proximity to the cavities. The fiber taper is used both to efficiently pump the cavity and collect the cavity emission.

  8. Optimization of the multiwavelength erbium-doped fiber laser in a unidirectional cavity without isolator

    Science.gov (United States)

    Sun, Guoyong; Chung, Youngjoo; Luo, Zhengqian; Cai, Zhiping; Ye, Chenchun

    2007-07-01

    Highly uniform multiwavelength erbium-doped fiber ring laser with an intra-cavity sine phase modulator is demonstrated. The flat output spectrum is achieved by optimizing the cavity structure, modulation amplitude and frequency of the sine phase modulator. 15 lasing lines with wavelength spacing of 0.9 nm appear simultaneously and stably in power differences less than 2 dB and the side mode suppression ratio higher than 32 dB. In addition, the proposed cavity can support unidirectional operation without optical isolators. The output power difference of about 20 dB is realized between counterclockwise and clockwise direction, which is almost independent of the pump power and lasing wavelengths.

  9. Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances.

    Science.gov (United States)

    Kang, M S; Joly, N Y; Russell, P St J

    2013-02-15

    We report the experimental demonstration of a passively mode-locked Er-doped fiber ring laser operating at the 337th harmonic (1.80 GHz) of the cavity. The laser makes use of highly efficient Raman-like optoacoustic interactions between the guided light and gigahertz acoustic resonances trapped in the micron-sized solid glass core of a photonic crystal fiber. At sufficient pump power levels the laser output locks to a repetition rate corresponding to the acoustic frequency. A stable optical pulse train with a side-mode suppression ratio higher than 45 dB was obtained at low pump powers (~60 mW).

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  11. ISR RF cavities

    CERN Multimedia

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  12. Dental cavities

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001055.htm Dental cavities To use the sharing features on this page, please enable JavaScript. Dental cavities are holes (or structural damage) in the ...

  13. The Uncertainty Evaluation of Determining the Moisture in Gases by the Method of Cavity Ring Down Spectroscopy%光腔衰荡光谱法测定气体中微痕量水不确定度评估

    Institute of Scientific and Technical Information of China (English)

    周鑫; 周泽义

    2012-01-01

    介绍了基于光腔衰荡光谱法测定气体中的微量水的方法原理,该方法适用于含量为0.2×10-9 ~20×10-6 mol/mol的所有气体中水分的测定.建立了光谱分析法的原始数学模型,对测定方法的不确定度进行了评估,结果表明该方法的扩展不确定度为(8 ~20)×10-9 mol/mol(k =2,p =95%).%A new method for determining the moisture in gases by the cavity ring down spectroscopy is available to measure the concentration between 0. 2 × 10-9 mol/mol and 20 × 10 -6 mol/moL A mathematical model is established for the uncertainty evaluation,and the results of the expanded uncertaunties are in the range of (8 ~20) × 10-9mol/mol (k =2, p = 95%).

  14. LEP Radio Frequency Copper Cavity

    CERN Multimedia

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  15. Properties of Optical Resonant Modes in Ⅲ-Nitride Semiconductor Micro-Cone Cavities

    Institute of Scientific and Technical Information of China (English)

    DAI Lun; ZHANG Bei; LIN Jing-Yu; JIANG Hong-Xing

    2001-01-01

    Arrays of Ⅲ-nitride semiconductor micro-cone cavities with a base diameter of 3.3μm were fabricated by ion beam etching. The micro-cones consisted of 58 nm thick multiple quantum wells of ln0.22Ga0.78N/In0.06Ga0.94N as well as a 1.5μm thick epilayer of GaN. Optical resonant modes from a single micro-cone could be clearly observed in the photoluminescence spectra at temperatures up to 200K under a pumping power density two orders of magnitude lower than that for the Ⅲ-nitride semiconductor micro-disk or micro-ring cavity. Using a novel optical ray tracing method, we have figured out four main types of optical resonant cavities inside the three-dimensional micro-cone, including two Fabry-Perot (F-P) mode types as well as two Whispering Gallery mode types. The three corresponding mode spacings among the four agree perfectly with the experimental results. The advantages of this new class of micro-cavity over the other micro-cavities are discussed. These findings are expected to have an impact on the design of the ultraviolet/blue micro-cavity laser diodes.

  16. Constant-Pressure Hydraulic Pump

    Science.gov (United States)

    Galloway, C. W.

    1982-01-01

    Constant output pressure in gas-driven hydraulic pump would be assured in new design for gas-to-hydraulic power converter. With a force-multiplying ring attached to gas piston, expanding gas would apply constant force on hydraulic piston even though gas pressure drops. As a result, pressure of hydraulic fluid remains steady, and power output of the pump does not vary.

  17. Generation of radially and azimuthally polarized beams in Yb:YAG laser with intra-cavity lens and birefringent crystal.

    Science.gov (United States)

    Thirugnanasambandam, Manasadevi P; Senatsky, Yuri; Ueda, Ken-ichi

    2011-01-31

    We demonstrated the operation of cw diode-pumped Yb:YAG laser in radial or azimuthal polarized (RP or AP) beams using a combination of birefringent uniaxial crystal (c-cut YVO4 or α-BBO) and lens as intra-cavity elements. RP and AP doughnut modes (M2 = 2-2.5, polarization extinction ratio 50-100:1) with output power up to 60 mW were generated. Apart from doughnut modes, RP or AP ring-like off-axis oscillations and multi-ring beams with mixed RP and AP were also observed at the output of this laser scheme. Using intra-cavity short focus lenses with spherical aberrations AP or RP modes of higher orders was obtained. Mechanism of mode selection in the laser is discussed. The large variety of beams with axially symmetric polarizations from the output of the proposed laser scheme may find applications in different fields.

  18. Nanofriction in Cavity Quantum Electrodynamics.

    Science.gov (United States)

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  19. Cavity-enhanced absorption for optical refrigeration

    CERN Document Server

    Seletskiy, Denis V; Sheik-Bahae, Mansoor

    2009-01-01

    A 20-fold increase over the single path optical absorption is demonstrated with a low loss medium placed in a resonant cavity. This has been applied to laser cooling of Yb:ZBLAN glass resulting in 90% absorption of the incident pump light. A coupled-cavity scheme to achieve active optical impedance matching is analyzed.

  20. Nonlinear all-optical switch based on a white-light cavity

    Science.gov (United States)

    Li, Na; Xu, Jingping; Song, Ge; Zhu, Chengjie; Xie, Shuangyuan; Yang, Yaping; Zubairy, M. Suhail; Zhu, Shi-Yao

    2016-04-01

    It is well known that there is a bottleneck for nonlinear all-optical switching, namely, the switching power and the switching time cannot be lowered simultaneously. A lower switching power requires a resonator with a high quality (Q ) factor, but leads to a longer switching time. We propose to overcome this bottleneck by replacing the nonlinear cavity in such an all-optical switch by a white-light cavity. This can be done by doping three-level atoms in the ring resonator and applying incoherent pump and coherent driving fields on it. The white-light cavity possesses broadband resonance in a linear region. Therefore, for the incident pulse, a broad range of frequency components can take part in the nonlinear process, and so it requires lower power to achieve switching compared to the conventional ring resonator. On the other hand, the refractive index of a white-light cavity has negative dispersion, leading to a fast group velocity. This results in a shorter time to build up the resonant response, yielding a short switching time.

  1. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  2. Octave-spanning spectrum of femtosecond Yb:fiber ring laser at 528 MHz repetition rate in microstructured tellurite fiber.

    Science.gov (United States)

    Wang, Guizhong; Jiang, Tongxiao; Li, Chen; Yang, Hongyu; Wang, Aimin; Zhang, Zhigang

    2013-02-25

    The octave-spanning spectrum was generated in a tellurite glass based microstructured fiber pumped by a 528 MHz repetition rate Yb:fiber ring laser without amplification. The laser achieved 40% output optical-to-optical efficiency with the output power of 410 mW. By adjusting the grating pair in the cavity, this oscillator can work at different cavity dispersion regimes with the shortest dechirped pulse width of 46 fs. The output pulses were then launched into a high-nonlinearity tellurite fiber, which has the zero-dispersion wavelength at ~1 μm. The high nonlinearity coefficient (1348 km⁻¹W⁻¹) and the matched zero-dispersion wavelength with pump laser enable the octave-spanning supercontinuum generated from 750 nm to 1700 nm with the coupled pulse energy above 10 pJ.

  3. Vascular ring

    Science.gov (United States)

    ... subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... Vascular ring is rare. It accounts for less than 1% of all congenital heart problems. The condition ...

  4. Determination of inlet transmission and conversion efficiencies for in situ measurements of the nocturnal nitrogen oxides, NO3, N2O5 and NO2, via pulsed cavity ring-down spectroscopy.

    Science.gov (United States)

    Fuchs, Hendrik; Dubé, William P; Ciciora, Steven J; Brown, Steven S

    2008-08-01

    Pulsed cavity ring-down spectroscopy is a highly sensitive method for direct absorption spectroscopy that has been applied to in situ detection of NO3, N2O5 and NO2 in the atmosphere from a variety of platforms, including ships, aircraft, and towers. In this paper, we report the development of schemes to significantly improve the accuracy of these measurements. This includes the following: (1) an overall improvement in the inlet transmission efficiencies (92 +/- 2% for NO3 and 97 +/- 1% for N2O5) achieved primarily through a reduction in the inlet residence time; and (2) the development of a calibration procedure that allows regular determination of these efficiencies in the field by addition of NO3 or N2O5 to the inlet from a portable source followed by conversion of NO3 to NO2. In addition, the dependence of the instrument's sensitivity and accuracy to a variety of conditions encountered in the field, including variations in relative humidity, aerosol loading, and VOC levels, was systematically investigated. The rate of degradation of N2O5 transmission efficiency on the inlet and filter system due to the accumulation of inorganic aerosol was determined, such that the frequency of filter changes required for accurate measurements could be defined. In the absence of aerosol, the presence of varying levels of relative humidity and reactive VOC were found to be unimportant factors in the instrument's performance. The 1 sigma accuracy of the NO3, N2O5, and NO2 measured with this instrument are -9/+12, -8/+11, +/- 6%, respectively, where the -/+ signs indicate that the actual value is low/high relative to the measurement. The largest contribution to the overall uncertainty is now due to the NO3 absorption cross section rather than the inlet transmission efficiency.

  5. Measurement of size-dependent single scattering albedo of fresh biomass burning aerosols using the extinction-minus-scattering technique with a combination of cavity ring-down spectroscopy and nephelometry

    Science.gov (United States)

    Singh, Sujeeta; Fiddler, Marc N.; Bililign, Solomon

    2016-11-01

    Biomass burning (BB) aerosols have a significant effect on regional climate, and represent a significant uncertainty in our understanding of climate change. Using a combination of cavity ring-down spectroscopy and integrating nephelometry, the single scattering albedo (SSA) and Ångstrom absorption exponent (AAE) were measured for several North American biomass fuels. This was done for several particle diameters for the smoldering and flaming stage of white pine, red oak, and cedar combustion. Measurements were done over a wider wavelength range than any previous direct measurement of BB particles. While the offline sampling system used in this work shows promise, some changes in particle size distribution were observed, and a thorough evaluation of this method is required. The uncertainty of SSA was 6 %, with the truncation angle correction of the nephelometer being the largest contributor to error. While scattering and extinction did show wavelength dependence, SSA did not. SSA values ranged from 0.46 to 0.74, and were not uniformly greater for the smoldering stage than the flaming stage. SSA values changed with particle size, and not systematically so, suggesting the proportion of tar balls to fractal black carbon change with fuel type/state and particle size. SSA differences of 0.15-0.4 or greater can be attributed to fuel type or fuel state for fresh soot. AAE values were quite high (1.59-5.57), despite SSA being lower than is typically observed in wildfires. The SSA and AAE values in this work do not fit well with current schemes that relate these factors to the modified combustion efficiency of a burn. Combustion stage, particle size, fuel type, and fuel condition were found to have the most significant effects on the intrinsic optical properties of fresh soot, though additional factors influence aged soot.

  6. A Magnetically Coupled Cryogenic Pump

    Science.gov (United States)

    Hatfield, Walter; Jumper, Kevin

    2011-01-01

    Historically, cryogenic pumps used for propellant loading at Kennedy Space Center (KSC) and other NASA Centers have a bellows mechanical seal and oil bath ball bearings, both of which can be problematic and require high maintenance. Because of the extremely low temperatures, the mechanical seals are made of special materials and design, have wearing surfaces, are subject to improper installation, and commonly are a potential leak path. The ball bearings are non-precision bearings [ABEC-1 (Annular Bearing Engineering Council)] and are lubricated using LOX compatible oil. This oil is compatible with the propellant to prevent explosions, but does not have good lubricating properties. Due to the poor lubricity, it has been a goal of the KSC cryogenics community for the last 15 years to develop a magnetically coupled pump, which would eliminate these two potential issues. A number of projects have been attempted, but none of the pumps was a success. An off-the-shelf magnetically coupled pump (typically used with corrosive fluids) was procured that has been used for hypergolic service at KSC. The KSC Cryogenics Test Lab (CTL) operated the pump in cryogenic LN2 as received to determine a baseline for modifications required. The pump bushing, bearings, and thrust rings failed, and the pump would not flow liquid (this is a typical failure mode that was experienced in the previous attempts). Using the knowledge gained over the years designing and building cryogenic pumps, the CTL determined alternative materials that would be suitable for use under the pump design conditions. The CTL procured alternative materials for the bearings (bronze, aluminum bronze, and glass filled PTFE) and machined new bearing bushings, sleeves, and thrust rings. The designed clearances among the bushings, sleeves, thrust rings, case, and case cover were altered once again using experience gained from previous cryogenic pump rebuilds and designs. The alternative material parts were assembled into

  7. A 200 MHz prebunching cavity

    CERN Multimedia

    1977-01-01

    This cavity was installed in the PS ring and proved very efficient in providing a modulation on the PS beam before it is injected into the SPS machine. Moreover it allowed longitudinal instabilities studies at high intensities. Roberto Cappi stands on the left.

  8. A unidirectional multiwavelength erbium-doped fiber ring laser without isolator at room temperature

    Science.gov (United States)

    Sun, Guoyong; Qu, Ronghui; Yang, Jing; Wang, Xiangzhao; Fang, Zujie

    2005-01-01

    Highly uniform multiwavelength erbium-doped fiber ring laser with a sinusoidal phase modulator and line intervals of 0.45 nm is demonstrated. The flat and stable output distribution is realized by optimizing modulation voltage and frequency for the sine phase modulator. Simultaneous 30 lasing lines are obtained in power difference less than 2 dB. In addition, the implemented cavity structure can support unidirectional operation even without optical isolators. The power difference between clockwise and counterclockwise direction is higher than 20 dB, almost independent of pumping powers and lasing wavelengths in lasing operation.

  9. accelerating cavity

    CERN Multimedia

    On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  10. Finemet cavity impedance studies

    CERN Document Server

    Persichelli, S; Migliorati, M; Salvant, B

    2013-01-01

    The aim of the study is to evaluate the impedance of the Finemet kicker cavity to be installed in the PS straight section 02 during LS1, under realistic assumptions of bunch length. Time domain simulations with CST Particle Studio have been performed in order to get the impedance of the cavity and make a comparison with the longitudinal impedance measured for a single cell prototype. The study has been performed on simplified 3D geometries imported from a mechanical CATIA drawing, assuming that the simplications have small impact on the nal results. Simulations confirmed that the longitudinal impedance observed with measurements can be excited by bunches circulating in the PS. In the six-cells Finemet cavity, PS bunches circulating in the center can excite a longitudinal impedance, the real part of which has a maximum of 2 kOhm at 4 MHz. This mode does not seem to have any transverse component. All the eigenmodes of the cavity are strongly damped by the Finemet rings: we predict to have no issues regarding tr...

  11. Optimization of the multiwavelength erbium-doped fiber laser in a unidirectional cavity without an isolator

    Science.gov (United States)

    Sun, Guo-Yong; Qu, Ronghui; Yang, Jingxin; Wang, Xiangzhao

    2005-09-01

    A highly uniform multiwavelength erbium-doped fiber ring laser with an intracavity sine phase modulator is demonstrated. The flat output spectrum is achieved by optimizing the cavity structure, modulation amplitude, and frequency of the sine phase modulator. Fifteen lasing lines with wavelength spacing of 0.9 nm appear simultaneously and stably with power differences less than 2 dB and side-mode suppression ratio higher than 32 dB. In addition, the proposed cavity can support unidirectional operation without optical isolators. An output power difference of about 20 dB is realized between the counterclockwise and clockwise directions, which is almost independent of the pump power and lasing wavelengths.

  12. Ring blowers. Ring blower

    Energy Technology Data Exchange (ETDEWEB)

    Nakahara, Y.; Okamura, T.; Takahashi, M. (Fuji Electric Co. Ltd., Tokyo (Japan))

    1991-06-10

    Features, structures and several products of ring blowers were outlined. The ring blower is featured by its medium characteristics because it is higher in air pressure than a turboblower and larger in airflow than a vane blower, and it is applicable flexibly to not only air blasting but various industrial fields such as suction transfer. As several products corresponding to various fields, the followings were outlined: the low noise type with optimum shapes of inlet, outlet and casing cover for reducing noises by 10 dB or more, the heat resistant, water-tight and explosion-proof types suitable for severe environmental conditions, the multi-voltage type for every country served at different voltages, the high air pressure type with two pressure rise stages, and the large airflow type with a wide impeller. In addition, as special use products, the glass fiber reinforced unsatulated polyester ring blower for respiration apparatus, and the variable speed blushless DC motor-driven one for medical beds were outlined. 2 refs., 9 figs., 1 tab.

  13. Accelerating RF cavity of the Booster

    CERN Multimedia

    1983-01-01

    Each of the 4 PS Booster rings has a single accelerating cavity.It consists of 2 quarter-wave ferrite-loaded resonators. 2 figure-of-eight loops tune the frequency throughout the accelerating cycle, from 3 to 8 MHz (from 50 MeV at injection to the original Booster energy of 800 MeV, 2 GeV today). The cavities have a flat design, to fit the ring-to-ring distance of 36 cm, and are forced-air cooled. The 2 round objects in the front-compartments are the final-stage power-tetrodes. See also 8111095.

  14. Accelerating RF cavity of the Booster

    CERN Multimedia

    CERN PhotoLab

    1981-01-01

    Each of the 4 PS Booster rings has a single accelerating cavity. It consists of 2 quarter-wave ferrite-loaded resonators. There are 2 figure-of-eight loops on the ferrite loads for tuning the frequency throughout the acceleration cycle, from 3 to 8 MHz (from 50 MeV at injection to the original Booster energy of 800 MeV, 2 GeV today). The cavities have a flat design, to fit the ring-to-ring distance of 36 cm. The tube for forced-air cooling is visible in the left front. See also 8301084.

  15. 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

  16. Diode-pumped dye laser

    Science.gov (United States)

    Burdukova, O. A.; Gorbunkov, M. V.; Petukhov, V. A.; Semenov, M. A.

    2016-10-01

    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.

  17. 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....

  18. Temperature Effect on Mechanical Properties of NBR-based Stator Rubber for Progressing Cavity Pump%螺杆泵定子用丁腈基橡胶的温度力学效应

    Institute of Scientific and Technical Information of China (English)

    赵海超; 王世杰; 王慧明; 吕晓仁

    2015-01-01

    In order to improve the service life of stator rubber used in the progressing cavity pump stator, NBR based rubbers with different acrylonitrile contents are chosen as the experimental materials and their variations in weight, volume, tensile strength and so on before and after immersion experiment are investigated according to the actual work environment. The results show that with an increase in the tempera-ture of crude oil, the weight, volume and elongation at break of the NBR rubber with low acrylonitrile content increase and its hardness de-creases, while the NBR rubber with high acrylonitrile content shows the opposite tendency. The tensile strength of three kinds of NBR rub-bers decreases with the increase in the temperature of crude oil. The NBR rubber with high acrylonitrile content shows the better heat resis-tance and mechanical performance due to its dense microstructure.%为提高螺杆泵定子橡胶的使用寿命,从螺杆泵的实际工作环境出发,以不同丙烯腈含量的丁腈橡胶为试验材料,通过测试试样在原油介质中质量、体积以及抗拉强度的一系列变化,研究定子橡胶的温度力学效应。结果表明:随着原油温度的升高,低丙烯腈丁腈橡胶的质量、体积和扯断伸长率逐渐增大,硬度逐渐降低;而高丙烯腈丁腈橡胶则显示相反的规律。三种橡胶的抗拉强度随着原油温度的升高逐渐降低。高丙烯腈含量的丁腈橡胶由于致密的组织结构具有良好的耐热性和力学性能。

  19. State of the Art SRF Cavity Performance

    CERN Document Server

    Lilje, L

    2004-01-01

    The paper will review superconducting RF cavity performance for β=1 cavities used in both linear and circular accelerators. These superconducting cavities are used in two kinds of applications: High current storage rings and efficient high duty cycle linacs. In recent years the performance of those cavities has been improving steadily. High accelerating gradients have been achieved using advanced surface preparation techniques like electropolishing and surface cleaning methods like high pressure water rinsing. High intensity beams can be handled with advanced higher-order-mode damping schemes.

  20. Saturn's Rings

    Science.gov (United States)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  1. Collar nut and thrust ring

    Science.gov (United States)

    Lowery, Guy B.

    1991-01-01

    A collar nut comprises a hollow cylinder having fine interior threads at one end for threadably engaging a pump mechanical seal assembly and an inwardly depending flange at the other end. The flange has an enlarged portion with a groove for receiving an O-ring for sealing against the intrusion of pumpage from the exterior. The enlarged portion engages a thrust ring about the pump shaft for crushing a hard O-ring, such as a graphite O-ring. The hard O-ring seals the interior of the mechanical seal assembly and pump housing against the loss of lubricants or leakage of pumpage. The fine threads of the hollow cylinder provide the mechanical advantage for crushing the hard O-ring evenly and easily with a hand tool from the side of the collar nut rather than by tightening a plurality of bolts from the end and streamlines the exterior surface of the mechanical seal. The collar nut avoids the spatial requirements of bolt heads at the end of a seal and associated bolt head turbulence.

  2. The LEP e+e−ring at the energy frontier of circular lepton colliders

    CERN Document Server

    Hofmann, Albert

    2016-01-01

    The Large Electron Positron ring (LEP) was a circular lepton collider at CERN. It operated at beam energies around 47GeV to produce the neutral Z0 particle and above 80 GeV to create pairs of the charged W± bosons. At these high energies the emission of synchrotron radiation was important and demanded a very high voltage of the RF-system. It also influenced the choice of many other machine parameters. This presentation tries to show how the basic accelerator physics was used to optimize the machine and to find innovative solutions for some problems: magnets with concrete between the laminations, modulated cavities, Nb-Cu superconducting cavities, nonevaporable getter pumps, optics analysis from multi-turn data and many more.

  3. Vortex rings

    Energy Technology Data Exchange (ETDEWEB)

    Akhmetov, D.G. [Lavrentiev Institute of Hydrodynamics, Novosibirsk (Russian Federation)

    2009-07-01

    This book presents a comprehensive coverage of the wide field of vortex rings. The book presents the results of systematic experimental investigations, theoretical foundation, as well as the practical applications of vortex rings, such as the extinction of fires at gushing gas and oil wells. All the basic properties of vortex rings as well as their hydrodynamic structures are presented. Special attention is paid to the formation and motion of turbulent vortex rings. (orig.)

  4. 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.

  5. Experimental studies of self-starting passive mode locking Er3 + -doped fiber ring soliton laser

    Institute of Scientific and Technical Information of China (English)

    刘东峰; 陈国夫; 王贤华

    1999-01-01

    The mechanism of femtosecond optical pulse generation in a self-starting Er3+-doped fiber ring solitonlaser and experimental research results are discussed. Using the nonlinear polarization rotation effect of the fiber for sat-urable absorbers (and then self-amplitude modulation) which acts as the mode locking mechanism in an Er3+-dopedfiber ring cavity laser, stable self-starting mode locking pulses have been generated. The shortest output pulse is 269 fs,with the central wavelength of 1.531 μm at the repetition rate of 21.37 MHz. The average output powers of the two terminators of the laser are 0.25 mW and 0.08 mW respectively. The threshold pump power which sustains the mode lock-ing is 15 mW. Under high pump power, the laser works in a high order harmonic mode locking state. The mode lockingpulse durations vs different cavity lengths are also studied.

  6. Spectrally and temporally resolved resonance shifts of a photonic crystal cavity switch

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Yu, Yi; Mørk, Jesper

    2016-01-01

    We present experimental results of temporally and spectrally resolved transmission measurements of a photonic crystal cavity using two-color pump-probe technique. With a gated spectral measurement, we measure the resonance shift's dependence on pump power.......We present experimental results of temporally and spectrally resolved transmission measurements of a photonic crystal cavity using two-color pump-probe technique. With a gated spectral measurement, we measure the resonance shift's dependence on pump power....

  7. Spectrally and temporally resolved resonance shifts of a photonic crystal cavity switch

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Yu, Yi; Mørk, Jesper

    2016-01-01

    We present experimental results of temporally and spectrally resolved transmission measurements of a photonic crystal cavity using two-color pump-probe technique. With a gated spectral measurement, we measure the resonance shift's dependence on pump power.......We present experimental results of temporally and spectrally resolved transmission measurements of a photonic crystal cavity using two-color pump-probe technique. With a gated spectral measurement, we measure the resonance shift's dependence on pump power....

  8. Ring theory

    CERN Document Server

    Rowen, Louis H

    1991-01-01

    This is an abridged edition of the author's previous two-volume work, Ring Theory, which concentrates on essential material for a general ring theory course while ommitting much of the material intended for ring theory specialists. It has been praised by reviewers:**""As a textbook for graduate students, Ring Theory joins the best....The experts will find several attractive and pleasant features in Ring Theory. The most noteworthy is the inclusion, usually in supplements and appendices, of many useful constructions which are hard to locate outside of the original sources....The audience of non

  9. 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.

  10. Ionization cooling ring for muons

    Directory of Open Access Journals (Sweden)

    R. Palmer

    2005-06-01

    Full Text Available Practical ionization cooling rings could lead to lower cost or improved performance in neutrino factory or muon collider designs. The ring modeled here uses realistic three-dimensional fields. The performance of the ring compares favorably with the linear cooling channel used in the second U.S. Neutrino Factory Study. The normalized 6D emittance of an ideal ring is decreased by a factor of approximately 240, compared with a factor of only 15 for the linear channel. We also examine such real-world effects as windows on the absorbers and rf cavities and leaving empty lattice cells for injection and extraction. For realistic conditions the ring decreases the normalized 6D emittance by a factor of 49.

  11. 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

  12. The MAX IV storage ring project.

    Science.gov (United States)

    Tavares, Pedro F; Leemann, Simon C; Sjöström, Magnus; Andersson, Ake

    2014-09-01

    The MAX IV facility, currently under construction in Lund, Sweden, features two electron storage rings operated at 3 GeV and 1.5 GeV and optimized for the hard X-ray and soft X-ray/VUV spectral ranges, respectively. A 3 GeV linear accelerator serves as a full-energy injector into both rings as well as a driver for a short-pulse facility, in which undulators produce X-ray pulses as short as 100 fs. The 3 GeV ring employs a multibend achromat (MBA) lattice to achieve, in a relatively short circumference of 528 m, a bare lattice emittance of 0.33 nm rad, which reduces to 0.2 nm rad as insertion devices are added. The engineering implementation of the MBA lattice raises several technological problems. The large number of strong magnets per achromat calls for a compact design featuring small-gap combined-function magnets grouped into cells and sharing a common iron yoke. The small apertures lead to a low-conductance vacuum chamber design that relies on the chamber itself as a distributed copper absorber for the heat deposited by synchrotron radiation, while non-evaporable getter (NEG) coating provides for reduced photodesorption yields and distributed pumping. Finally, a low main frequency (100 MHz) is chosen for the RF system yielding long bunches, which are further elongated by passively operated third-harmonic Landau cavities, thus alleviating collective effects, both coherent (e.g. resistive wall instabilities) and incoherent (intrabeam scattering). In this paper, we focus on the MAX IV 3 GeV ring and present the lattice design as well as the engineering solutions to the challenges inherent to such a design. As the first realisation of a light source based on the MBA concept, the MAX IV 3 GeV ring offers an opportunity for validation of concepts that are likely to be essential ingredients of future diffraction-limited light sources.

  13. Planetary Rings

    CERN Document Server

    Tiscareno, Matthew S

    2011-01-01

    Planetary rings are the only nearby astrophysical disks, and the only disks that have been investigated by spacecraft. Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 1e-7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close-range and in real-time in planetary rings. We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The main rings of Saturn comprise our system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty...

  14. A unidirectional Er3+-doped fiber ring laser without isolator

    DEFF Research Database (Denmark)

    Shi, Yuan; Sejka, Milan; Poulsen, Ove

    1995-01-01

    An Er3+-doped fiber ring laser with unidirectional operation without optical isolator has been investigated for different cavity conditions. The fiber ring laser cavity is built in such a way that the optical fields propagating in the two directions suffer different losses. As a consequence, the ......, the laser oscillation appears in a quasi-unidirectional form. By incorporating a fiber pigtailed bandpass filter to enhance mode competition, a purely unidirectional tunable fiber ring laser is obtained with high efficiency and broad tunability...

  15. Experiments with vortex rings in air

    Science.gov (United States)

    Hernández, R. H.; Cibert, B.; Béchet, C.

    2006-09-01

    We report quantitative experimental measurements of the instability of vortex rings generated in air. Vortex rings are created by pushing air through the circular orifice of a cylindrical cavity with a flat piston driven by a loudspeaker. Hot-wire anemometry provides accurate measurements of the velocity profile at all stages of the ring formation including stable and unstable rings. Flow visualization using a laser light sheet shows that the initially undisturbed vortex ring is progressively deformed in the azimuthal direction giving rise to a wavy azimuthal and periodic pattern in the circumference of the ring. The wavy pattern is steady, i.e., it does not rotate or translate during the ring's motion. However as the vortex motion progresses in the axial direction, the displaced portions of the ring are convected away from the initial undisturbed position and the wavy pattern grows with local Reynolds number.

  16. Numerical simulation and analysis for three-dimensional flow field of air-ejector of liquid ring pump%液环泵喷射器三维流场数值模拟分析

    Institute of Scientific and Technical Information of China (English)

    黄思; 罗力; 杨国蟒

    2012-01-01

    利用ANSYS CFX分软件及湍流模型,通过改变液环泵喷射器的结构参数,模拟其内部的三维流动探讨了结构参数对喷射器内部流场及性能的影响;重点分析了引射压力、喉嘴距和面积比对喷射器性能的影响;得到了喷射器性能(引射气量、喷射系数等)随喉嘴距、面积比的变化规律;模拟结果表明:几何参数的改变极大的影响着波系结构;在给定的设计工况下,存在一个最佳的面积比(约为10.15)及一个最优的喉嘴距(20mm)对应于最大的喷射系数,为喷射器的优化设计提供了依据.%By varying the structural parameter of ejector of liquid ring pump and simulating internal 3-D flow, the impact of structural parameter on internal flow field and performance of ejector is investigated with software package CFX and turbulence model, in which the impact of the injecting pressure, the throat-nozzle distance and the ratio of secondary area on performance of ejector is emphasized.And the varying regularity is obtained.That is the performance (airflow injected and ejecting coefficient and so on) of the ejector varies with the change of the throat-nozzle distance and the ratio ofareaThe result shows that the vary of geometric parameters impacts the wave structure significantly; The re are a optimum area ratio and an ideal throat-nozzle distance available under given condition corresponding to max.ejecling coefficient, which provides reference for optimal design of ejector.

  17. 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...

  18. Optomechanical photon shuttling between photonic cavities

    CERN Document Server

    Li, Huan

    2014-01-01

    Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave-mixing between photons and phonons and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong nonlocal effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a novel multi-cavity optomechanical device: a "photon see-saw", in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of the see-saw, are modulated anti-symmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation which strongly modulates the inter-cavity coupling and shuttles photons to the other...

  19. Optomechanical photon shuttling between photonic cavities.

    Science.gov (United States)

    Li, Huan; Li, Mo

    2014-11-01

    Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave mixing between photons and phonons, and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong non-local effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a multicavity optomechanical device in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of this 'photon see-saw', are modulated antisymmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation, which strongly modulates the inter-cavity coupling and shuttles photons to the other empty cavity during every oscillation cycle in a well-regulated fashion.

  20. Coupled Resonator Vertical Cavity Laser Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Chow, W.W.; Fischer, A.J.; Allerman, A.A.; Hou, H.Q.; Geib, K.M.

    1999-07-22

    For many applications, the device performance of edge emitting semiconductor lasers can be significantly improved through the use of multiple section devices. For example, cleaved coupled cavity (C3) lasers have been shown to provide single mode operation, wavelength tuning, high speed switching, as well as the generation of short pulses via mode-locking and Q-switching [1]. Using composite resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the coupling between the monolithic cavities, incorporate passive or active resonators which are spectrally degenerate or detuned, and to fabricate these devices in 2-dimensional arrays. Composite resonator vertical cavity lasers (CRVCL) have been examined using optical pumping and electrical injection [2-5]. We report on CRVCL diodes and show that efficient modulation of the laser emission can be achieved by either forward or reverse biasing the passive cavity within a CRVCL.

  1. Vertical external cavity surface emitting semiconductor lasers

    CERN Document Server

    Holm, M

    2001-01-01

    Active stabilisation showed a relative locked linewidth of approx 3 kHz. Coarse tuning over 7 nm was achieved using a 3-plate birefingent filter plate while fine-tuning using cavity length change allowed tuning over 250 MHz. Vertical external cavity semiconductor lasers have emerged as an interesting technology based on current vertical cavity semiconductor laser knowledge. High power output into a single transverse mode has attracted companies requiring good fibre coupling for telecommunications systems. The structure comprises of a grown semiconductor Bragg reflector topped with a multiple quantum well gain region. This is then included in an external cavity. This device is then optically pumped to promote laser action. Theoretical modelling of AIGaAs based VECSEL structures was undertaken, showing the effect of device design on laser characteristics. A simple 3-mirror cavity was constructed to assess the static characteristics of the structure. Up to 153 mW of output power was achieved in a single transver...

  2. Cavity magnomechanics

    Science.gov (United States)

    Zou, Chang-Ling; Zhang, Xufeng; Jiang, Liang; Tang, Hong

    2016-05-01

    Recently, cavity magnonics has attracted much attention for potential applications of coherent information transduction and hybrid quantum devices. The magnon is a collective spin wave excitation in ferromagnetic material. It is magnetically tunability, with long coherence time and non-reciprocical interaction with electro-magnetic fields. We report the coherent coupling between magnon, microwave photon and phonon. First, we demonstrate strong coupling and ultrastrong coupling between the magnon in YIG sphere and microwave photon in three-dimensional cavity. Then, based on the hybridized magnon-photon modes, we observe the triply resonant magnon-mcirowave photon-phonon coupling, where the ultrahigh-Q mechanical vibration of YIG sphere is dispersively coupled with the magnon via magnetostrictive interaction. We observe interesting phenomena, including electromagnetically induced transparency/absorption and parametric amplification. In particular, benefit from the large tunability of the magnon, we demonstrate a tunable microwave amplifier with gain as high as 30 dB. The single crystal YIG also has excellent optical properties, and thus provide a unique platform bridging MHz, GHz and THz information carriers. Finally, we present the latest progress towards coherent magnon to optical photon conversion.

  3. Planetary Rings

    Science.gov (United States)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  4. Solid-state ring laser gyroscope

    Science.gov (United States)

    Schwartz, S.

    The ring laser gyroscope is a rotation sensor used in most kinds of inertial navigation units. It usually consists in a ring cavity filled with a mixture of helium and neon, together with high-voltage pumping electrodes. The use of a gaseous gain medium, while resulting naturally in a stable bidirectional regime enabling rotation sensing, is however the main industrially limiting factor for the ring laser gyroscopes in terms of cost, reliability and lifetime. We study in this book the possibility of substituting for the gaseous gain medium a solid-state medium (diode-pumped Nd-YAG). For this, a theoretical and experimental overview of the lasing regimes of the solid-state ring laser is reported. We show that the bidirectional emission can be obtained thanks to a feedback loop acting on the states of polarization and inducing differential losses proportional to the difference of intensity between the counterpropagating modes. This leads to the achievement of a solid-state ring laser gyroscope, whose frequency response is modified by mode coupling effects. Several configurations, either mechanically or optically based, are then successively studied, with a view to improving the quality of this frequency response. In particular, vibration of the gain crystal along the longitudinal axis appears to be a very promising technique for reaching high inertial performances with a solid-state ring laser gyroscope. Gyrolaser à état solide. Le gyrolaser est un capteur de rotation utilisé dans la plupart des centrales de navigation inertielle. Dans sa forme usuelle, il est constitué d'une cavité laser en anneau remplie d'un mélange d'hélium et de néon pompé par des électrodes à haute tension. L'utilisation d'un milieu amplificateur gazeux, si elle permet de garantir naturellement le fonctionnement bidirectionnel stable nécessaire à la mesure des rotations, constitue en revanche la principale limitation industrielle des gyrolasers actuels en termes de coût, fiabilit

  5. Micro-Cavity Fluidic Dye Laser

    DEFF Research Database (Denmark)

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

    2003-01-01

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

  6. High beta lasing in micropillar cavities with adiabatic layer design

    DEFF Research Database (Denmark)

    Lermer, M.; Gregersen, Niels; Lorke, M.;

    2013-01-01

    We report on lasing in optically pumped adiabatic micropillar cavities, based on the AlAs/GaAs material system. A detailed study of the threshold pump power and the spontaneous emission β factor in the lasing regime for different diameters dc is presented. We demonstrate a reduction of the thresh...

  7. 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.

  8. Magnetopumping current in graphene Corbino pump

    Science.gov (United States)

    Abdollahipour, Babak; Moomivand, Elham

    2017-02-01

    We study conductance and adiabatic pumped charge and spin currents in a graphene quantum pump with Corbino geometry in the presence of an applied perpendicular magnetic field. Pump is driven by the periodic and out of phase modulations of the magnetic field and an electrostatic potential applied to the ring area of the pump. We show that Zeeman splitting, despite its smallness, suppresses conductance and pumped current oscillations at zero doping. Moreover, quite considerable spin conductance and pumped spin current are generated at low dopings due to Zeeman splitting. We find that pumped charge and spin currents increase by increasing the magnetic field, with small oscillations, until they are suppressed due to the effect of nonzero doping and Zeeman splitting.

  9. Observation of Transparency of Erbium-doped Silicon nitride in photonic crystal nanobeam cavities

    CERN Document Server

    Gong, Yiyang; Yerci, Selcuk; Li, Rui; Stevens, Martin J; Baek, Burm; Nam, Sae Woo; Negro, Luca Dal; Vuckovic, Jelena

    2010-01-01

    One-dimensional nanobeam photonic crystal cavities are fabricated in an Er-doped amorphous silicon nitride layer. Photoluminescence from the cavities around 1.54 um is studied at cryogenic and room temperatures at different optical pump powers. The resonators demonstrate Purcell enhanced absorption and emission rates, also confirmed by time-resolved measurements. Resonances exhibit linewidth narrowing with pump power, signifying absorption bleaching and the onset of stimulated emission in the material at both 5.5 K and room temperature. We estimate from the cavity linewidths that Er has been pumped to transparency at the cavity resonance wavelength.

  10. SUPRAMITRAL RING

    Directory of Open Access Journals (Sweden)

    Rajesh G

    2011-11-01

    Full Text Available Supra mitral ring is a rare cause for congenital mitral valve obstr uction. The reported incidence of supramitral ring is 0.2-0.4% in general population and 8% in patients with congenital mitral valve disease. The condition is characterized by an abnormal ridge of connective tissue often circumferential in shape ,on the atrial side of the mitral valve encroaching on the orifice of the mitral valve. It may adhere to the leaflets of the valve and restrict their movements. Although a supramitral ring may be rarely nonobstructive, it often results in mitral valve inflow obstruction.

  11. Mode-locking and Q-switching in multi-wavelength fiber ring laser using low frequency phase modulation.

    Science.gov (United States)

    Jun, Chang Su; Kim, Byoung Yoon

    2011-03-28

    We describe experimental investigation of pulsed output from a multi-wavelength fiber ring laser incorporating low frequency phase modulation with large modulation amplitude. The Erbium-doped fiber (EDF) ring laser generated more than 8 wavelength channels with the help of a phase modulator operating at 26.2 kHz and a periodic intra-cavity filter. For most cases, the laser output is pulsed in the form of mode-locking at 5.62 MHz and/or Q-switching at harmonic and sub-harmonic of the phase modulation frequency. Chaotic pulse output is also observed. The behavior of the output pulses are described as functions of pump power and phase modulation amplitude. The relative intensity noise (RIN) value of a single wavelength channel is measured to be under -100 dB/Hz (-140 dB/Hz beyond 1.5 GHz).

  12. Experimental investigation of high energy noise-like pulses from a long cavity erbium-doped fiber laser

    Science.gov (United States)

    Li, Kexuan; Guoyu, Heyang; Tian, Jinrong; Song, Yanrong

    2016-11-01

    The high energy noise-like pulses (NLPs) were experimentally investigated in a passively mode-locked erbium-doped fiber laser with a long ring cavity by using nonlinear polarization rotation technique. Large net normal group-velocity dispersion of the cavity is estimated as high as 6.46 ps2, which is beneficial to formation of high-energy pulses. With the total pump power of 970 mW (the pump powers of forward pump and backward pump are set at the value of 455 mW and 515 mW, respectively), a stable ultrahigh energy rectangular-shape pulse emission with the pulse duration of 35 ns was observed. The energy of square packet with a fundamental repetition rate of 141.6 kHz is as high as 840 nJ. The signal-to-noise is higher than 60 dB in RF spectrum. The feature of NLPs is confirmed by the coherent spike of autocorrelation trace. When the pump power is beyond 970 mW, the mode locking operation with fundamental repetition rate cannot be achieved despite of the large range variation of polarization controller (PC) settings. However, the forthorder harmonic mode locking can be observed, the square pulse packet duration still remains at ˜ 35 ns. The experimental results demonstrated that the ultrahigh energy NLPs is only realized at the condition of special physical parameters and it is restricted by the number and intensity of ultra short pulses within the envelope to some extent.

  13. Alternative technique for implantation of biventricular support with HeartWare implantable continuous flow pump.

    Science.gov (United States)

    Krabatsch, Thomas; Stepanenko, Alexander; Schweiger, Martin; Kukucka, Marian; Ewert, Peter; Hetzer, Roland; Potapov, Evgenij

    2011-01-01

    In this case report, we describe a modification of the biventricular implantation of the HeartWare HVAD. A 28-year-old man with dilative cardiomyopathy presented with biventricular decompensation. The patient underwent implantation of two HeartWare HVADs for biventricular support. Because of low flow of the right pump (2 L/min), a right ventricular angiogram and repeated transesophageal echocardiography (TEE) were done and showed that the pump was compressing the right ventricle. Operative revision was performed, resulting in removal of the right pump and placement into the right atrium, so that it was located in the right pleural cavity. The HVAD fixation ring on the free wall of the right ventricle was left in place, and the opening was closed with an individually designed titanium plug. The findings of this case are that implantation of the HeartWare HVAD for right ventricular (RV) support may be safely performed in atrial position, with individually designed plugs allowing safe and quick removal of the HeartWare pump. This might be used as a "bail-out" strategy when necessary.

  14. Determinantal rings

    CERN Document Server

    Bruns, Winfried

    1988-01-01

    Determinantal rings and varieties have been a central topic of commutative algebra and algebraic geometry. Their study has attracted many prominent researchers and has motivated the creation of theories which may now be considered part of general commutative ring theory. The book gives a first coherent treatment of the structure of determinantal rings. The main approach is via the theory of algebras with straightening law. This approach suggest (and is simplified by) the simultaneous treatment of the Schubert subvarieties of Grassmannian. Other methods have not been neglected, however. Principal radical systems are discussed in detail, and one section is devoted to each of invariant and representation theory. While the book is primarily a research monograph, it serves also as a reference source and the reader requires only the basics of commutative algebra together with some supplementary material found in the appendix. The text may be useful for seminars following a course in commutative ring theory since a ...

  15. Cave Rings

    Science.gov (United States)

    2010-10-13

    hypothesis, that cave rings are formed in the same manner as coffee rings[3], that is, due to the enhanced deposition at the edges of sessile drops ...ring’ is the deposit formed when a sessile drop of a solution containing dissolved particles, such as coffee or salt, dries. This was investigated by...who expanded on Deegan et al.[3] to find an exact form for the evaporation flux over a sessile drop . It turns out that solving 179 for the flux is

  16. Cavities/Tooth Decay

    Science.gov (United States)

    Cavities/tooth decay Overview By Mayo Clinic Staff Cavities are permanently damaged areas in the hard surface of your teeth ... into tiny openings or holes. Cavities, also called tooth decay or caries, are caused by a combination of ...

  17. Vascular rings.

    Science.gov (United States)

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Triangular and honeycomb lattices of cold atoms in optical cavities

    Science.gov (United States)

    Safaei, Shabnam; Miniatura, Christian; Grémaud, Benoît.

    2015-10-01

    We consider a two-dimensional homogeneous ensemble of cold bosonic atoms loaded inside two optical cavities and pumped by a far-detuned external laser field. We examine the conditions for these atoms to self-organize into triangular and honeycomb lattices as a result of superradiance. By collectively scattering the pump photons, the atoms feed the initially empty cavity modes. As a result, the superposition of the pump and cavity fields creates a space-periodic light-shift external potential and atoms self-organize into the potential wells of this optical lattice. Depending on the phase of the cavity fields with respect to the pump laser, these minima can either form a triangular or a hexagonal lattice. By numerically solving the dynamical equations of the coupled atom-cavity system, we have shown that the two stable atomic structures at long times are the triangular lattice and the honeycomb lattice with equally populated sites. We have also studied how to drive atoms from one lattice structure to another by dynamically changing the phase of the cavity fields with respect to the pump laser.

  19. Non-Gaussian statistics and extreme waves in a nonlinear optical cavity.

    Science.gov (United States)

    Montina, A; Bortolozzo, U; Residori, S; Arecchi, F T

    2009-10-23

    A unidirectional optical oscillator is built by using a liquid crystal light valve that couples a pump beam with the modes of a nearly spherical cavity. For sufficiently high pump intensity, the cavity field presents complex spatiotemporal dynamics, accompanied by the emission of extreme waves and large deviations from the Gaussian statistics. We identify a mechanism of spatial symmetry breaking, due to a hypercycle-type amplification through the nonlocal coupling of the cavity field.

  20. Transverse and Quantum Effects in Light Control by Light; (A) Parallel Beams: Pump Dynamics for Three Level Superfluorescence; and (B) Counterflow Beams: An Algorithm for Transverse, Full Transient Effects in Optical Bi-Stability in a Fabryperot Cavity.

    Science.gov (United States)

    1983-01-01

    Collaborations: (i) Physics A. Dr. Charles M. Bowden (MICOM) - Two-level amplifier output stabilisation and three-ievel pump dynamics B. Professor Michael ...like a Foucault pendulum. (See Fig. 6b). The SF process is a unique macroscopic manifestation of quantum fluctuations, even though they are proportional...otherwise. (b) No level degeneracy, T2 = T2 =, KL = 0. (c) T2 = m. (d) T2 = . Ce) KL = 0. (f) KL 5. (g) No level degeneracy. Fig. 6b. Foucault pendulum co

  1. 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 ...

  2. 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.

  3. Cavity-enhanced laser cooling of solid-state materials in a standing-wave cavity

    Institute of Scientific and Technical Information of China (English)

    Youhua Jia; Biao Zhong; Jianping Yin

    2008-01-01

    We propose a new method to cool the Yba+-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique: the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.

  4. APS storage ring vacuum system

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

    1990-01-01

    The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.

  5. S-102 Transfer Pump Restriction Modeling Results

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.; Johnson, Kenneth I.; Rector, David R.; Trent, Donald S.

    2008-03-27

    It was determined that a radioactive waste leak in the Hanford S Farm in the vicinity of the S-102 retrieval pump discharge occurred because of over-pressurization and failure of the S-102 dilution water supply hose while operating the retrieval pump in reverse with an obstructed suction cavity and an unobstructed flow path to the dilution water supply hose. This report describes efforts to identify plausible scenarios for the waste leak to occur.

  6. 火电厂单级水环真空泵成套机组改造%A Study on the Renovation of the Integral Unit of the Single-stage Water-ring Vacuum Pump in the Thermal Power Plant

    Institute of Scientific and Technical Information of China (English)

    彭长俊

    2016-01-01

    The single-stage water-ring vacuum pump was damaged by cavitation accumulation after years of operation and seriously affected the security of the operation of the unit.In order to solve it,the pump has been replaced by the anti-cavitation two-stage cone-type vacuum pump which can lessen and even avoid cavitation,enhance the secu-rity of the operation of the unit and reduce the operating cost.%因多年运行的汽蚀累积作用而损坏的单极真空泵无法正常运行,严重影响了机组运行的安全性。针对这一问题,将其更换为抗汽蚀性较好的双击锥体真空泵,减弱甚至避免了汽蚀现象的产生,不但提高了机组运行的安全性,还降低了运行成本。

  7. 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.

  8. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  9. Analysis on Vibrating Causes of Multistage Centrifugal Pumps and Solutions%多级离心泵振动原因分析及解决办法

    Institute of Scientific and Technical Information of China (English)

    胡桂清; 王兵和; 陈存利; 王永祥; 刘炎

    2012-01-01

    对多级离心泵的异常振动原因进行查找分析,将止推间隙、平衡盘问隙,叶轮口环与泵体口环导叶口环之间的间隙做了合理的调整,密封腔直口与泵体的同心度,首级叶轮壳体腐蚀严重穿腔,进行补焊处理,对泵体产生振动的原因进行简单的阐述,并提出有针对性的解决方法,最终使泵达到良好的运行状态.%Abnormal vibriation reasons of multistage centrifugal pumps were analyzed, then some measures were carried out, such as rationally adjusting the clearance of thrust, clearance of balance disk, clearance between impeller ring and pump mouth ring, checking concentricity between direct export of seal cavity and pump body, welding the place where breakage happened in the first stage impeller casing because of severe corrosion. At last, the pumps can run very well.

  10. Cavity Optomechnics with 150nm-thick GaAs Membrane

    DEFF Research Database (Denmark)

    Usami, K.; Melholt Nielsen, B.; Naesby, A.

    2010-01-01

    -coupled to a Fabry-P´erot cavity formed between the membrane and a mirror (Finesse: 24) inside a vacuum chamber (10 7Torr), is used to lock the cavity length at the cavity resonant slope and to induce mechanical oscillations by modulating the intensity from the offset level for ring down measurements. We observe...

  11. 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.

  12. Ring interferometry

    CERN Document Server

    Malykin, Grigorii B; Zhurov, Alexei

    2013-01-01

    This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

  13. Crab Cavity Development

    CERN Document Server

    Calaga, R; Burt, G; Ratti, A

    2015-01-01

    The HL-LHC upgrade will use deflecting (or crab) cavities to compensate for geometric luminosity loss at low β* and non-zero crossing angle. A local scheme with crab cavity pairs across the IPs is used employing compact crab cavities at 400 MHz. Design of the cavities, the cryomodules and the RF system is well advanced. The LHC crab cavities will be validated initially with proton beam in the SPS.

  14. Electrostatically tunable optomechanical "zipper" cavity laser

    CERN Document Server

    Perahia, Raviv; Meenehan, Sean; Alegre, Thiago P Mayer; Painter, Oskar

    2010-01-01

    A tunable nanoscale "zipper" laser cavity, formed from two doubly clamped photonic crystal nanobeams, is demonstrated. Pulsed, room temperature, optically pumped lasing action at a wavelength of 1.3 micron is observed for cavities formed in a thin membrane containing InAsP/GaInAsP quantum-wells. Metal electrodes are deposited on the ends of the nanobeams to allow for micro-electro-mechanical actuation. Electrostatic tuning and modulation of the laser wavelength is demonstrated at a rate of 0.25nm/V^2 and a frequency as high as 6.7MHz, respectively.

  15. Pulsed pumping of semiconductor disk lasers.

    Science.gov (United States)

    Hempler, Nils; Hopkins, John-Mark; Kemp, Alan J; Schulz, Nico; Rattunde, Marcel; Wagner, Joachim; Dawson, Martin D; Burns, David

    2007-03-19

    Efficient operation of semiconductor disk lasers is demonstrated using uncooled and inexpensive 905nm high-power pulsed semiconductor pump lasers. Laser emission, with a peak power of 1.7W, is obtained from a 2.3mum semiconductor disk laser. This is seven times the power achieved under continuous pumping. Analysis of the time-dependent spectral characteristics of the laser demonstrate that significant device heating occurs over the 100-200ns duration of the pumping pulse - finite element modelling of the thermal processes is undertaken in support of these data. Spectral narrowing to below 0.8nm is obtained by using an intra-cavity birefringent filter.

  16. On SAP-rings

    OpenAIRE

    Zhixiang, Wu

    2006-01-01

    The rings whose simple right modules are absolutely pure are called right $SAP$-rings. We give a new characterization of right $SAP$ rings, right $V$ rings, and von Neumann regular rings. We also obtain a new decomposition theory of right selfinjective von Neumann regular rings. The relationships between $SAP$-rings, $V$-rings, and von Neumann regular rings are explored. Some recent results obtained by Faith are generalized and the results of Wu-Xia are strengthened.

  17. Cross-splicing method for compensating fiber birefringence in polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution.

    Science.gov (United States)

    Wang, Yunzheng; Zhang, Liqiang; Zhuo, Zhuang; Guo, Songzhen

    2016-07-20

    We propose a cross-splicing method, for the first time to our knowledge, to compensate the effect of fiber birefringence in a polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution. This method has been investigated numerically and experimentally. The results indicate that stable mode-locking pulses can be obtained in the cavity with this method; otherwise, no mode-locking states are achieved. The design processes of the laser cavity are presented. Pulses with single pulse energy of 2.1 nJ are generated at pump power of 460 mW. The spectral bandwidth and pulse duration are 17.5 nm and 11.7 ps, respectively. The tunability of the laser is also studied. The central wavelength can be tuned from 1023.2 to 1045.9 nm.

  18. High repetition rate Q-switched Er3+-doped fiber ring laser

    DEFF Research Database (Denmark)

    Sejka, Milan; Poulsen, Christian; Shi, Yuan

    1993-01-01

    In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity......In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity...

  19. 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

  20. 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: ...

  1. Comparison of different side-pumping configurations for high power laser diode pumped solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Junqing Meng(孟俊清); Weibiao Chen(陈卫标); Xia Hou(侯霞); Qiquan Hu(胡企铨)

    2003-01-01

    Ray-tracing method is used to simulate the distribution of absorption in crystal rod for different sidepumping configuration. The distribution of pumping power and absorption efficiency is compared, and the numerical results are presented. The results show that the more uniform pumping and the higher absorption coefficient are obtained with a diffuse cavity. And the method of the slow axis of laser diode stack perpendicular to the axis of lasing gives the higher central pumping density.

  2. Widely tunable Vernier ring laser on hybrid silicon.

    Science.gov (United States)

    Hulme, J C; Doylend, J K; Bowers, J E

    2013-08-26

    A hybrid silicon tunable Vernier ring laser is designed and fabricated by integration of two intra-cavity ring resonators, hybrid III-V-on-silicon gain elements, and resistive heaters for thermal tuning. Thermal tuning of more than 40 nm is demonstrated with side mode suppression ratio greater than 35 dB and linewidth of 338 kHz.

  3. Polarization properties of laser-diode-pumped micro-grained Nd:YAG ceramic lasers

    CERN Document Server

    Otsuka, Kenju

    2008-01-01

    Detailed polarization properties have been examined in laser-diode-pumped (LD-pumped) micro-grained ceramic Nd:YAG lasers in different microchip cavity configurations. Stable linearly-polarized single-frequency oscillations, whose polarization direction coincides with that of an LD pump light, were observed in an external cavity scheme. While, in the case of a thin-slice laser scheme with coated reflective ends, elliptically-polarized single-frequency operations took place in the low pump-power regime and dynamic instabilities appeared, featuring self-induced antiphase modulations among counter-rotating circularly-polarized components belonging to the same longitudinal mode, with increasing the pump power

  4. Compact KGd(WO4)2 picosecond pulse-train synchronously pumped broadband Raman laser.

    Science.gov (United States)

    Gao, Xiao Qiang; Long, Ming Liang; Meng, Chen

    2016-08-20

    We demonstrate an efficient approach to realizing an extra-cavity, synchronously pumped, stimulated Raman cascaded process under low repetition frequency (1 kHz) pump conditions. We also construct a compact KGd(WO4)2 (KGW) crystal picosecond Raman laser that has been configured as the developed method. A pulse-train green laser pumped the corresponding 70 mm long KGW crystal Raman cavity. The pulse train contains six pulses, about 800 ps separated, for every millisecond; thus, it can realize synchronous pumping between pump pulse and the pumped Raman cavity. The investigated system produced a collinear Raman laser output that includes six laser lines covering the 532 to 800 nm spectra. This is the first report on an all-solid-state, high-average-power picosecond collinear multi-wavelength (more than three laser components) laser to our knowledge. This method has never been reported on before in the synchronously pumped stimulated Raman scattering (SRS) realm.

  5. Ultracompact optical circulator based on a uniformly magnetic magnetophotonic annular Bragg cavity

    CERN Document Server

    Śmigaj, Wojciech; Romero-Vivas, Javier; Guenneau, Sébastien; Dagens, Béatrice; Gralak, Boris; Vanwolleghem, Mathias

    2011-01-01

    We have developed a theoretical framework that allows an efficient design of integrated optical circulators based on non-reciprocal magneto-optical cavities. Using this approach we have analysed different possible layouts for nonreciprocal resonant cavities. This investigation has allowed us to propose a new class of miniaturized integrated optical circulators that achieve simultaneously strong optical circulation while maintaining reasonable technological feasibility. Their layout is based on a radial Bragg cavity formed by arranging centrosymmetric annular magneto-optic rings. The circulator ports are standard rib waveguides, butt-coupled to the ring cavity by possibly cutting the outer cavity rings. Using a coupled mode description of the complete cavity/waveguide-port system, it is shown that it is indispensable to take possible direct port-to-port coupling into account for a proper optimization of the device. Including these optimization parameters in finite element simulations has led us to propose a st...

  6. Ponderomotive light squeezing with atomic cavity optomechanics

    CERN Document Server

    Brooks, Daniel W C; Brahms, Nathan; Purdy, Thomas P; Schreppler, Sydney; Stamper-Kurn, Dan M

    2011-01-01

    Accessing distinctly quantum aspects of the interaction between light and the position of a mechanical object has been an outstanding challenge to cavity-optomechanical systems. Only cold-atom implementations of cavity optomechanics have indicated effects of the quantum fluctuations in the optical radiation pressure force. Here we use such a system, in which quantum photon-number fluctuations significantly drive the center of mass of an atomic ensemble inside a Fabry-Perot cavity. We show that the optomechanical response both amplifies and ponderomotively squeezes the quantum light field. We also demonstrate that classical optical fluctuations can be attenuated by 26 dB or amplified by 20 dB with a weak input pump power of < 40 pW, and characterize the optomechanical amplifier's frequency-dependent gain and phase response in both the amplitude and phase-modulation quadratures.

  7. Collective multiphoton blockade in cavity quantum electrodynamics

    Science.gov (United States)

    Zhu, C. J.; Yang, Y. P.; Agarwal, G. S.

    2017-06-01

    We present a study of collective multiphoton blockade in coherently driven atoms in a single-mode cavity. Considering two atoms strongly coupled to an optical cavity, we show that the two-photon blockade with two-photon antibunching, and the three-photon blockade with three-photon antibunching can be observed simultaneously. The three-photon blockade probes both dressed states in the two-photon and three-photon spaces. The two-photon and three-photon blockades strongly depend on the location of the two atoms in the strong-coupling regime. The asymmetry in the atom-cavity coupling constants opens pathways for multiphoton blockade which is also shown to be sensitive to the atomic decay and pumping strengths. The work presented here predicts many quantum statistical features due to the collective behavior of atoms and can be useful to generate nonclassical photon pairs.

  8. Dawn of Cavity Spintronics

    OpenAIRE

    Hu, Can-Ming

    2015-01-01

    Merging the progress of spintronics with the advancement in cavity quantum electrodynamics and cavity polaritons, a new field of Cavity Spintronics is forming, which connects some of the most exciting modern physics, such as quantum information and quantum optics, with one of the oldest science on the earth, the magnetism.

  9. Pump shaft failures - a compendium of case studies

    CSIR Research Space (South Africa)

    Bernt, F

    2001-04-01

    Full Text Available of failure. Pump shafts are generally exposed to the liquid being pumped either on a continual basis or at certain locations along the length of the shaft. Specialised sealing arrangements comprising sleeves and o-rings can be used to reduce the amount...

  10. Er-doped fiber ring laser gyroscopes operating in continuous waves

    Institute of Scientific and Technical Information of China (English)

    Jingren Qian; Jue Su; Xuxu Wang; Bing Zhu

    2007-01-01

    A direction related polarizer was inserted into a ring laser cavity to eliminate one of the two eigen-modes as well as spatial hole burning of the gain medium in a bidirectional Er-doped fiber ring laser. Thus, a fiber ring laser gyroscope (FRLG) operating in continuous wave was demonstrated. A beat signal of over 30-dB noise was observed and a good inear relation between the beat frequency shift and cavity rotation rate was obtained.

  11. Origami rings

    CERN Document Server

    Buhler, Joe; de Launey, Warwick; Graham, Ron

    2010-01-01

    Motivated by a question in origami, we consider sets of points in the complex plane constructed in the following way. Let $L_\\alpha(p)$ be the line in the complex plane through $p$ with angle $\\alpha$ (with respect to the real axis). Given a fixed collection $U$ of angles, let $\\RU$ be the points that can be obtained by starting with $0$ and $1$, and then recursively adding intersection points of the form $L_\\alpha(p) \\cap L_\\beta(q)$, where $p, q$ have been constructed already, and $\\alpha, \\beta$ are distinct angles in $U$. Our main result is that if $U$ is a group with at least three elements, then $\\RU$ is a subring of the complex plane, i.e., it is closed under complex addition and multiplication. This enables us to answer a specific question about origami folds: if $n \\ge 3$ and the allowable angles are the $n$ equally spaced angles $k\\pi/n$, $0 \\le k < n$, then $\\RU$ is the ring $\\Z[\\zeta_n]$ if $n$ is prime, and the ring $\\Z[1/n,\\zeta_{n}]$ if $n$ is not prime, where $\\zeta_n := \\exp(2\\pi i/n)$ is ...

  12. Unidirectional ring-laser operation using sum-frequency mixing

    DEFF Research Database (Denmark)

    Tidemand-Lichtenberg, Peter; Cheng, Haynes Pak Hay; Pedersen, Christian

    2010-01-01

    A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss for the...... where lossless second-order nonlinear materials are available. Numerical modeling and experimental demonstration of parametric-induced unidirectional operation of a diode-pumped solid-state 1342 nm cw ring laser are presented....

  13. Supersonic flows over cavities

    Institute of Scientific and Technical Information of China (English)

    Tianwen FANG; Meng DING; Jin ZHOU

    2008-01-01

    The characteristics of supersonic cold flows over cavities were investigated experimentally and numer-ically, and the effects of cavities of different sizes on super-sonic flow field were analyzed. The results indicate that the ratio of length to depth L/D within the range of 5-9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does not alter the overall structure of the cavity flow within the range of 30°-60°, but it can exert obvious effect on the evolvement of shear layer and vortexes in cavities.

  14. Beam cavity interaction

    CERN Document Server

    Gamp, A

    2011-01-01

    We begin by giving a description of the rf generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, rf feedback, and feed-forward are described. Examples of digital rf phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  15. RESONANT CAVITY EXCITATION SYSTEM

    Science.gov (United States)

    Baker, W.R.; Kerns, Q.A.; Riedel, J.

    1959-01-13

    An apparatus is presented for exciting a cavity resonator with a minimum of difficulty and, more specifically describes a sub-exciter and an amplifier type pre-exciter for the high-frequency cxcitation of large cavities. Instead of applying full voltage to the main oscillator, a sub-excitation voltage is initially used to establish a base level of oscillation in the cavity. A portion of the cavity encrgy is coupled to the input of the pre-exciter where it is amplified and fed back into the cavity when the pre-exciter is energized. After the voltage in the cavity resonator has reached maximum value under excitation by the pre-exciter, full voltage is applied to the oscillator and the pre-exciter is tunned off. The cavity is then excited to the maximum high voltage value of radio frequency by the oscillator.

  16. Development of a miniature intraventricular axial flow blood pump.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Cavity-enhanced frequency up-conversion in rubidium vapour

    CERN Document Server

    Offer, Rachel F; Riis, Erling; Franke-Arnold, Sonja; Arnold, Aidan S

    2016-01-01

    We report the first use of a ring cavity to both enhance the output power and dramatically narrow the linewidth ($<1\\,$MHz) of blue light generated by four wave mixing in a rubidium vapour cell. We find that the high output power available in our cavity-free system leads to power broadening of the generated blue light linewidth. Our ring cavity removes this limitation, allowing high output power and narrow linewidth to be achieved concurrently. As the cavity blue light is widely tunable over the $^{85}$Rb 5S$_{1/2} \\,\\,F=3$ $\\rightarrow$ 6P$_{3/2}$ transition, this narrow linewidth light would be suitable for second-stage laser cooling, which could be valuable for efficient $^{85}$Rb BEC production.

  18. Cavity turnover and equilibrium cavity densities in a cottonwood bottomland

    Science.gov (United States)

    Sedgwick, James A.; Knopf, Fritz L.

    1992-01-01

    A fundamental factor regulating the numbers of secondary cavity nesting (SCN) birds is the number of extant cavities available for nesting. The number of available cavities may be thought of as being in an approximate equilibrium maintained by a very rough balance between recruitment and loss of cavities. Based on estimates of cavity recruitment and loss, we ascertained equilibrium cavity densities in a mature plains cottonwood (Populus sargentii) bottomland along the South Platte River in northeastern Colorado. Annual cavity recruitment, derived from density estimates of primary cavity nesting (PCN) birds and cavity excavation rates, was estimated to be 71-86 new cavities excavated/100 ha. Of 180 active cavities of 11 species of cavity-nesting birds found in 1985 and 1986, 83 were no longer usable by 1990, giving an average instantaneous rate of cavity loss of r = -0.230. From these values of cavity recruitment and cavity loss, equilibrium cavity density along the South Platte is 238-289 cavities/100 ha. This range of equilibrium cavity density is only slightly above the minimum of 205 cavities/100 ha required by SCN's and suggests that cavity availability may be limiting SCN densities along the South Platte River. We submit that snag management alone does not adequately address SCN habitat needs, and that cavity management, expressed in terms of cavity turnover and cavity densities, may be more useful.

  19. Tens of GHz Tantalum pentoxide-based micro-ring all-optical modulator for Si photonics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chung-Lun; Chi, Wen-Chun; Chiu, Yi-Jen; Lin, Yuan-Yao; Hung, Yung-Jr; Chu, Ann-Kuo [Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Hsieh, Cheng-Hsuan; Lin, Gong-Ru [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei (China); Shih, Min-Hsiung [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (China); Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Lee, Chao-Kuei [Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

    2017-03-15

    A tantalum pentoxide-based (Ta{sub 2}O{sub 5}-based) micro-ring all-optical modulator was fabricated. The refractive index inside the micro-ring cavity was modified using the Kerr effect by injecting a pumped pulse. The transmittance of the ring resonator was controlled to achieve all-optical modulation at the wavelength of the injected probe. When 12 GHz pulses with a peak power of 1.2 W were coupled in the ring cavity, the transmission spectrum of the Ta{sub 2}O{sub 5} resonator was red-shifted by 0.04 nm because of the Kerr effect. The relationship between the modulation depth and gap of the Ta{sub 2}O{sub 5} directional coupler is discussed. An optimized gap of 1100 nm was obtained, and a maximum buildup factor of 11.7 with 84% modulation depth was achieved. The nonlinear refractive index of Ta{sub 2}O{sub 5} at 1.55 μm was estimated as 3.4 x 10{sup -14} cm{sup 2}/W based on the Kerr effect, which is almost an order of magnitude higher than that of Si{sub 3}N{sub 4}. All results indicate that Ta{sub 2}O{sub 5} has potential for use in nonlinear waveguide applications with modulation speeds as high as tens of GHz. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. 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.

  1. 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

  2. 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.

  3. Apparatus and process for passivating an SRF cavity

    Science.gov (United States)

    Myneni, Ganapati Rao; Wallace, John P

    2014-12-02

    An apparatus and process for the production of a niobium cavity exhibiting high quality factors at high gradients is provided. The apparatus comprises a first chamber positioned within a second chamber, an RF generator and vacuum pumping systems. The process comprises placing the niobium cavity in a first chamber of the apparatus; thermally treating the cavity by high temperature in the first chamber while maintaining high vacuum in the first and second chambers; and applying a passivating thin film layer to a surface of the cavity in the presence of a gaseous mixture and an RF field. Further a niobium cavity exhibiting high quality factors at high gradients produced by the method of the invention is provided.

  4. Adiabatic embedment of nanomechanical resonators in photonic microring cavities

    CERN Document Server

    Xiong, Chi; Li, Mo; Rooks, Michael; Tang, Hong X

    2014-01-01

    We report a circuit cavity optomechanical system in which a nanomechanical resonator is adiabatically embedded inside an optical ring resonator with ultralow transition loss. The nanomechanical device forms part of the top layer of a horizontal silicon slot ring resonator, which enables dispersive coupling to the dielectric substrate via a tapered nanogap. Our measurements show nearly uncompromised optical quality factors (Q) after the release of the mechanical beam.

  5. LEP copper accelerating cavities

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  6. Widely tunable linear-cavity multiwavelength fiber laser with distributed Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    M. Ajiya; M. H. Al-Mansoori; M. A. Mahdi

    2011-01-01

    We demonstrate a multiple wavelength Brillouin/erbium fiber laser in a linear cavity configuration. The laser cavity is made up of a fiber loop mirror on one end of the resonator and a virtual mirror generated from the distributed stimulated Brillouin scattering effect on the other end. Due to the weak reflectivity provided by the virtual mirror, self-lasing cavity modes are completely suppressed from the laser cavity. At Brillouin pump and 1480-nm pump powers of 2 and 130 mW, respectively, 11 channels of the demonstrated laser with an average total power of 7.13 dBm can freely be tuned over a span of 37-nm wavelength from 1530 to 1567 nm.%@@ We demonstrate a multiple wavelength Brillouin/erbium fiber laser in a linear cavity configuration.The laser cavity is made up of a fiber loop mirror on one end of the resonator and a virtual mirror generated from the distributed stimulated Brillouin scattering effect on the other end.Due to the weak reflectivity provided by the virtual mirror, self-lasing cavity modes are completely suppressed from the laser cavity.At Brillouin pump and 1480-nm pump powers of 2 and 130 mW, respectively, 11 channels of the demonstrated laser with an average total power of 7.13 dBm can freely be tuned over a span of 37-nm wavelength from 1530 to 1567 nm.

  7. Mode-locked Pr3+-doped silica fiber laser with an external cavity

    DEFF Research Database (Denmark)

    Shi, Yuan; Poulsen, Christian; Sejka, Milan

    1994-01-01

    We present a Pr3+-doped silica-based fiber laser mode-locked by using a linear external cavity with a vibrating mirror. Stable laser pulses with a FWHM of less than 44 ps, peak power greater than 9 W, and repetition rate up to 100 MHz are obtained. The pulse width versus cavity mismatch ΔL and pump...

  8. Prime rings with PI rings of constants

    CERN Document Server

    Kharchenko, V K; Rodríguez-Romo, S

    1996-01-01

    It is shown that if the ring of constants of a restricted differential Lie algebra with a quasi-Frobenius inner part satisfies a polynomial identity (PI) then the original prime ring has a generalized polynomial identitiy (GPI). If additionally the ring of constants is semiprime then the original ring is PI. The case of a non-quasi-Frobenius inner part is also considered.

  9. R&D of BEPCII 500 MHz superconducting cavity

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Beijing Electron-Positron Collider Upgrade (BEPCII) adopts two 500 MHz superconducting cavities (SCCs) in each ring for higher accelerated gradient, higher Q and lower impedance (Wang et al. The proceedings of SRF’07). There’s no spare cavity due to the limited time and funding during BEPCII construction. If any serious trouble happened on either one of the two cavities and could not be recovered in a short time, the operation of BEPCII facility will be affected. Therefore, since 2009 three spare cavities have been fabricated in China to ensure reliable operation, and two of them have been successfully vertically tested in January and July 2011. This paper will briefly present the manufacture, post-process and vertical test performance of the 500 MHz spare cavities.

  10. Fabrication and Testing of Deflecting Cavities for APS

    Energy Technology Data Exchange (ETDEWEB)

    Mammosser, John; Wang, Haipeng; Rimmer, Robert; Jim, Henry; Katherine, Wilson; Dhakal, Pashupati; Ali, Nassiri; Jim, Kerby; Jeremiah, Holzbauer; Genfa, Wu; Joel, Fuerst; Yawei, Yang; Zenghai, Li

    2013-09-01

    Jefferson Lab (Newport News, Virginia) in collaboration with Argonne National Laboratory (Argonne, IL) has fabricated and tested four first article, 2.8 GHz, deflecting SRF cavities, for Argonne's Short-Pulse X-ray (SPX) project. These cavities are unique in many ways including the fabrication techniques in which the cavity cell and waveguides were fabricated. These cavity subcomponents were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The challenging cavity and helium vessel design and fabrication results from the stringent RF performance requirements required by the project and operation in the APS ring. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

  11. 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.

  12. 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

  13. 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.

  14. Radical theory of rings

    CERN Document Server

    Gardner, JW

    2003-01-01

    Radical Theory of Rings distills the most noteworthy present-day theoretical topics, gives a unified account of the classical structure theorems for rings, and deepens understanding of key aspects of ring theory via ring and radical constructions. Assimilating radical theory's evolution in the decades since the last major work on rings and radicals was published, the authors deal with some distinctive features of the radical theory of nonassociative rings, associative rings with involution, and near-rings. Written in clear algebraic terms by globally acknowledged authorities, the presentation

  15. Cavity spin optodynamics

    CERN Document Server

    Brahms, N

    2010-01-01

    The dynamics of a large quantum spin coupled parametrically to an optical resonator is treated in analogy with the motion of a cantilever in cavity optomechanics. New spin optodynamic phenonmena are predicted, such as cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent amplification and damping of spin, and the spin optodynamic squeezing of light.

  16. SPS accelerating cavity

    CERN Multimedia

    1980-01-01

    One of the SPS acceleration cavities (200 MHz, travelling wave structure). On the ceiling one sees the coaxial transmission line which feeds the power from the amplifier, located in a surface building above, to the upstream end of the cavity. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8104138, 8302397.

  17. Superconducting cavities for LEP

    CERN Multimedia

    1983-01-01

    Above: a 350 MHz superconducting accelerating cavity in niobium of the type envisaged for accelerating electrons and positrons in later phases of LEP. Below: a small 1 GHz cavity used for investigating the surface problems of superconducting niobium. Albert Insomby stays on the right. See Annual Report 1983 p. 51.

  18. SPS accelerating cavity

    CERN Multimedia

    CERN PhotoLab

    1981-01-01

    One of the SPS accelerating cavities (200 MHz, travelling wave structure). The power that is fed into the upstream end of the cavity is extracted at the downstream end and sent into a dump load. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8011289, 8302397.

  19. 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.

  20. High efficiency supercontinuum generation using ultra-long Raman fiber cavities.

    Science.gov (United States)

    El-Taher, Atalla E; Ania-Castañón, Juan D; Karalekas, Vassilis; Harper, Paul

    2009-09-28

    Supercontinuum generation in a multi-fiber ultra-long Raman fiber laser cavity is experimentally investigated for the first time. We demonstrate significantly enhanced spectral flatness and supercontinuum generation efficiency using only conventional single mode silica fiber. With a pump power of only 1.63W a approximately 15 dB bandwidth >260 nm wide (from 1440 to >1700 nm) supercontinuum source is reported with a flatness of nm using an optimised hybrid TW/HNLF cavity. We address the dependence of the supercontinuum spectrum on the input pump power and ultra-long Raman cavity.

  1. Self-organization in Kerr-cavity-soliton formation in parametric frequency combs

    Science.gov (United States)

    Wen, Y. Henry; Lamont, Michael R. E.; Strogatz, Steven H.; Gaeta, Alexander L.

    2016-12-01

    We show that self-organization and synchronization underlie Kerr-cavity-soliton formation in parametric frequency combs. By reducing the Lugiato-Lefever equation to a set of phase equations, we find that self-organization arises from a two-stage process via pump-degenerate and pump-nondegenerate four-wave mixing. The reduced phase equations are akin to the Kuramoto model of coupled oscillators and intuitively explain the origin of the pump phase offset, predict antisymmetrization of the intracavity field before phase synchronization, and clarify the role of chaos in Kerr-cavity-soliton formation in parametric combs.

  2. Twisted Electromagnetic Modes and Sagnac Ring-Lasers

    CERN Document Server

    Burton, D A; Tucker, R W; Wiltshire, D L; Burton, David A.; Noble, Adam; Tucker, Robin W.; Wiltshire, David L.

    2005-01-01

    A new approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting cavity (modelling a ring-laser), is constructed. It is shown that for well-defined conditions there exist TE and TM modes with respect to the longitudinal axis of the cavity. A twisted mode spectrum is found to depend on the integrated Frenet torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity. The analysis is motivated by attempts to use ring-lasers to measure terrestrial gravito-magnetism or the Lense-Thirring effect produced by the rotation of the Earth.

  3. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  4. Birth Control Ring

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Birth Control Ring KidsHealth > For Teens > Birth Control Ring A A A What's in this article? ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ring ...

  5. Resonator Coupling of Two Ring Cavity, Argon-Ion Lasers.

    Science.gov (United States)

    1987-12-01

    mirrors CMi and CM2, which coupled the backward traveling-waves, and coupling beamsplitters CB1 and CB2 , which coupled the forward traveling waves...these elements were replaced with flat, 32% beamsplitters. Alignment of beamsplitters CB1 and CB2 was difficult because each output beam was...Output Couplers--- --- CM2 C B 1 CB2 Figure 4: Orientation of Coupling Beamsplitters. Coupling beamsplitters CB1 and CB2 were roughly aligned such that

  6. 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.

  7. Making of a nonlinear optical cavity

    CERN Document Server

    Martínez-Lorente, R; Esteban-Martín, A; García-Monreal, J; Roldán, E; Silva, F

    2016-01-01

    In the article we explain in detail how to build a photorefractive oscillator (PRO), which is a laser-pumped nonlinear optical cavity containing a photorefractive crystal. The specific PRO whose construction we describe systematically, is based on a Fabry-Perot optical cavity working in a non-degenerate four wave-mixing configuration. This particular PRO has the property that the generated beam exhibits laser-like phase invariance and, as an application, we show how a suitably modulated injected beam converts the output field from phase-invariant into phase-bistable. While the emphasis is made on the making of the experimental device and on the way measurements are implemented, some introduction to the photorefractive effect as well as to the necessary concepts of nonlinear dynamics are also given, so that the article is reasonably self-contained.

  8. Actin Rings of Power.

    Science.gov (United States)

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles.

  9. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  10. PCM Vulcain : a pumping revolution in the thermal recovery of heavy oil

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-01-15

    Nearly half of the world's oil reserves are made up of unconventional heavy oil that requires thermal recovery methods. Since the oil pumped to the surface is extremely hot (350 degrees C), traditional pumps such as standard progressing cavity pumps, sucker rod pumps and electrical submersible pumps are limited in terms of maximum operating temperature. For that reason, PCM developed the PCM Vulcain, a revolutionary all-metal pump that is capable of extracting heavy oil and aggressive fluids during thermal recovery. The applications include artificial lifting in SAGD processes and artificial lifting in cyclic steam stimulation processes. The pump withstands the extreme downhole temperatures of thermal oil recovery and can pump extremely hot and extremely viscous fluids. PCM Vulcain provides all the advantages and flexibility of progressing cavity pump technology at extreme temperatures. The rotary action of PCM Vulcain outperforms beam pumps in overall system efficiency and it is less fragile than electric submersible pumps. PCM Vulcain provides extremely low submergence production capability and can operate at low downhole pressures and higher viscosities. PCM Vulcain also has lower capital expenditure than comparable submersible and rod pumps. In addition, it offers lower workover costs and reduced installation and operational complexity. The pump's seals reduce the risk of on-site leakage, thereby reducing environmental impact. PCM Vulcain has field-proven performance in some of the world's major unconventional oilfields, including the Athabasca oil sands in northern Alberta. 1 fig.

  11. 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

  12. Eigenpolarization theory of monolithic nonplanar ring oscillators

    Science.gov (United States)

    Nilsson, Alan C.; Gustafson, Eric K.; Byer, Robert L.

    1989-01-01

    Diode-laser-pumped monolithic nonplanar ring oscillators (NPROs) in an applied magnetic field can operate as unidirectional traveling-wave lasers. The diode laser pumping, monolithic construction, and unidirectional oscillation lead to narrow linewidth radiation. Here, a comprehensive theory of the eigenpolarizations of a monolithic NPRO is presented. It is shown how the properties of the integral optical diode that forces unidirectional operation depend on the choice of the gain medium, the applied magnetic field, the output coupler, and the geometry of the nonplanar ring light path. Using optical equivalence theorems to gain insight into the polarization characteristics of the NPRO, a strategy for designing NPROs with low thresholds and large loss nonreciprocities is given. An analysis of the eigenpolarizations for one such NPRO is presented, alternative optimization approaches are considered, and the prospects for further reducing the linewidths of these lasers are briefly discussed.

  13. SPS RF Accelerating Cavity

    CERN Multimedia

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X

  14. SPS RF Cavity

    CERN Multimedia

    1975-01-01

    The picture shows one of the two initially installed cavities. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: by end 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412017X, 7411048X, 7505074.

  15. High efficiency SHG of orbital angular momentum light in an external cavity

    CERN Document Server

    Zhou, Zhi-Yuan; Ding, Dong-Sheng; Jiang, Yun-Kun; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2014-01-01

    Traditional methods for generating orbital angular momentum (OAM) light include holographic diffraction gratings, vortex phase plate and spatial light modulator. In this article, we report a new method for high efficient OAM light generation. By pumping an external cavity contains a quasi phase matching nonlinear crystal with a fundamental OAM carrying light and properly aligning the cavity, mode matching between the pump light and the cavitys higher order Laguerre-Gaussian (LG) mode is achieved, conversion efficiency up to 10.3 percentage have been obtained. We have demonstrated that the cavity can stably operate at its higher order LG mode just as Gaussian mode for the first time. The SHG light possesses a doubled OAM value with respect to the pump light. The parameters that affect the beam quality and conversion efficiency are discussed in detail. Our work opens a brand new field in laser optics, and makes the first step toward high efficiency OAM light processing.

  16. Diode-pumped 1123-nm Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Guo(郭晓萍); Meng Chen(陈檬); Gang Li(李港); Bingyuan zhang(张炳元); Jiandong Yang(杨建东); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚)

    2004-01-01

    We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbOa (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.

  17. 372-mJ long pulse pyrotechnically pumped laser

    Institute of Scientific and Technical Information of China (English)

    Nan Xiao; Zongfu Jiang; Weihong Hua; Shengfu Yuan

    2008-01-01

    A pyrotechnically pumped Nd glass laser is demonstrated by the use of pyrotechnic flashlamps composed of several chemical materials arranged in a stable plane concave resonator cavity. The flashlamp was made of chemical mixture with oxidant, fuel, and binder. The emission spectrum of pyrotechnic flame covered most of the absorption bands of Nd3+ in phosphate glass. Under 4.56-g chemical mixture pumping, long pulse output power of about 5.5 W was achieved.

  18. A high-finesse Fabry–Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Rakhman, A., E-mail: rahim@ornl.gov [Syracuse University, Department of Physics, Syracuse, NY 13244 (United States); Research Accelerator Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hafez, M. [Old Dominion University, Applied Research Center, Norfolk, VA 23529 (United States); Nanda, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Benmokhtar, F. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Duquesne University, Pittsburgh, PA 15282 (United States); Camsonne, A. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Cates, G.D. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Dalton, M.M. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Franklin, G.B. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Friend, M. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Michaels, R.W. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Nelyubin, V. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Parno, D.S. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); University of Washington, Center for Experimental Nuclear Physics and Astrophysics and Department of Physics, Seattle, WA 98195 (United States); Paschke, K.D. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Quinn, B.P. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); and others

    2016-06-21

    A high-finesse Fabry–Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO{sub 3} crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.06 GeV and 50 μA.

  19. A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

    CERN Document Server

    Rakhman, A; Nanda, S; Benmokhtar, F; Camsonne, A; Cates, G D; Dalton, M M; Franklin, G B; Friend, M; Michaels, R W; Nelyubin, V; Parno, D S; Paschke, K D; Quinn, B P; Souder, P A; Tobias, W A

    2016-01-01

    A high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532~nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064~nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO$_{3}$ crystal. The maximum achieved green power at 5 W IR pump power is 1.74 W with a total conversion efficiency of 34.8\\%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7~kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7\\%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0\\% precision in polarization measurements of an electron beam with energy and current of 1.0~GeV and 50~$\\mu$A.

  20. Photon antibunching and nonlinear effects for a quantum dot coupled to a semiconductor cavity

    Science.gov (United States)

    Bello, F.; Whittaker, D. M.

    2010-09-01

    The models presented simulate pumping techniques that can be used on modern semiconductor devices which are capable of coupling a quantum dot and cavity mode in order to determine a more efficient method of producing a single-photon emitter while taking into consideration typical parameters which are achievable given today’s standards of coupling strength. Cavity quantum electrodynamics are incorporated in the calculations as we compare various pumping schemes for the system that either use on-resonant laser excitation or nonresonant excitation due to a wetting layer. In particular, we look to study how antibunching effects change for each method as the cavity finesse is increased toward the strong coupling regime. Experimentally these studies are equivalent to nonlinear pump-probe measurements, where a strong pump, either resonant or nonresonant, is used to excite the coupled system, and the resulting state is characterized using a weak, resonant probe beam.

  1. Superconducting travelling wave ring with high gradient accelerating section

    Energy Technology Data Exchange (ETDEWEB)

    Avrakhov, P.; Solyak, N.; /Fermilab

    2007-06-01

    Use of a superconducting traveling wave accelerating (STWA) structure instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting traveling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control traveling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.

  2. Tuned optical cavity magnetometer

    Science.gov (United States)

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  3. SPS RF cavity

    CERN Multimedia

    1974-01-01

    The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. A power of up to 790 kW can be supplied to each giving a total accelerating voltage of about 8 MV. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities.

  4. An aeroacoustically driven thermoacoustic heat pump.

    Science.gov (United States)

    Slaton, W V; Zeegers, J C H

    2005-06-01

    The mean flow of gas in a pipe past a cavity can excite the resonant acoustic modes of the cavity--much like blowing across the top of a bottle. The periodic shedding of vortices from the leading edge of the mouth of the cavity feeds energy into the acoustic modes which, in turn, affect the shedding of the next vortex. This so-called aeroacoustic whistle can excite very high amplitude acoustic standing waves within a cavity defined by coaxial side branches closed at their ends. The amplitude of these standing waves can easily be 20% of the ambient pressure at optimal gas flow rates and ambient pressures within the main pipe. A standing wave thermoacoustic heat pump is a device which utilizes the in-phase pressure and displacement oscillations to pump heat across a porous medium thereby establishing, or maintaining, a temperature gradient. Experimental results of a combined system of aeroacoustic sound source and a simple thermoacoustic stack will be presented.

  5. Investigation of frequency stability and design criteria of ring lasers

    DEFF Research Database (Denmark)

    Pedersen, Christian; Lichtenberg Hansen, P.; Buchhave, Preben

    1996-01-01

    We present a comprehensive Jones matrix analysis of two commonly used ring laser resonators. Different aspects on how to obtain low loss eigenmodes and/or high loss difference between the two directions of the cavity, and thus high frequency stability, are investigated. Also different approximati......We present a comprehensive Jones matrix analysis of two commonly used ring laser resonators. Different aspects on how to obtain low loss eigenmodes and/or high loss difference between the two directions of the cavity, and thus high frequency stability, are investigated. Also different...... approximations are evaluated. Since the theory has been kept general, the derived results can be applied to a large class of ring laser designs. Finally the influence of backscattered light on the stability is considered. Experimental results on two ring lasers are discussed....

  6. Geophysical observations at cavity collapse

    Science.gov (United States)

    Jousset, Philippe; Bazargan-Sabet, Behrooz; Lebert, François; Bernardie, Séverine; Gourry, Jean-Christophe

    2010-05-01

    In Lorraine region (France) salt layers at about 200 meters depth are exploited by Solvay using solution mining methodology which consists in extracting the salt by dissolution, collapsing the cavern overburden during the exploitation phase and finally reclaiming the landscape by creating a water area. In this process, one of the main challenges for the exploiting company is to control the initial 120-m diameter collapse so as to minimize possible damages. In order to detect potential precursors and understand processes associated with such collapses, a wide series of monitoring techniques including micro seismics, broad-band seismology, hydro-acoustic, electromagnetism, gas probing, automatic leveling, continuous GPS, continuous gravity and borehole extensometry was set-up in the frame of an in-situ study carried out by the "Research Group for the Impact and Safety of Underground Works" (GISOS, France). Equipments were set-up well before the final collapse, giving a unique opportunity to analyze a great deal of information prior to and during the collapse process which has been successfully achieved on February the 13th, 2009 by controlling the cavity internal pressure. In this work, we present the results of data recorded by a network of 3 broadband seismometers, 2 accelerometers, 2 tilt-meters and a continuously gravity meter. We relate the variations of the brine pumping rate with the evolutions of the induced geophysical signals and finally we propose a first mechanical model for describing the controlled collapse. Beyond the studied case, extrapolation of the results obtained might contribute to the understanding of uncontrolled cavity collapses, such as pit-craters or calderas at volcanoes.

  7. CMC blade with pressurized internal cavity for erosion control

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Crespo, Andres; Goike, Jerome Walter

    2016-02-02

    A ceramic matrix composite blade for use in a gas turbine engine having an airfoil with leading and trailing edges and pressure and suction side surfaces, a blade shank secured to the lower end of each airfoil, one or more interior fluid cavities within the airfoil having inlet flow passages at the lower end which are in fluid communication with the blade shank, one or more passageways in the blade shank corresponding to each one of the interior fluid cavities and a fluid pump (or compressor) that provides pressurized fluid (nominally cool, dry air) to each one of the interior fluid cavities in each airfoil. The fluid (e.g., air) is sufficient in pressure and volume to maintain a minimum fluid flow to each of the interior fluid cavities in the event of a breach due to foreign object damage.

  8. Impeller behavior and displacement of the VentrAssist implantable rotary blood pump.

    Science.gov (United States)

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Woodard, John C

    2004-03-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 microm to 230 microm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy-current proximity sensors and laser proximity sensors. The second experiment used Hall-effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, theta(x), and theta(y)). The sixth degree of freedom, the rotation about the impeller axis (theta(z)), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 micro m to 222 microm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing.

  9. SPS accelerating cavity

    CERN Multimedia

    1976-01-01

    The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.

  10. accelerating cavity from LEP

    CERN Multimedia

    This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.

  11. Dental Sealants Prevent Cavities

    Science.gov (United States)

    ... MMWR RSS VitalSigns RSS Error processing SSI file Dental Sealants Prevent Cavities Effective protection for children Language: ... more use of sealants and reimbursement of services. Dental care providers can Apply sealants to children at ...

  12. Homogeneous solutions for elliptically polarized light in a cavity containing materials with electric and magnetic nonlinearities

    CERN Document Server

    Martin, D A

    2015-01-01

    We study evolution equations and stationary homogeneous solutions for electric and magnetic field amplitudes in a ring cavity with flat mirrors. The cavity is filled with a positive or negative refraction index material with third order Kerr-like electric nonlinearities and also magnetic nonlinearities, which can be relevant in metamaterials. We consider the degree of freedom of polarization in the incident beam. It is found that considering a magnetic nonlinearity increases the variety of possible qualitatively different solutions. A classification of solutions is proposed in terms of the number of bifurcations. The analysis can be useful for the implementation of optical switching or memory storage using ring cavities with non linear materials.

  13. An all-optical buffer based on temporal cavity solitons operating at 10 Gb/s

    CERN Document Server

    Jang, Jae K; Schröder, Jochen; Eggleton, Benjamin J; Murdoch, Stuart G; Coen, Stéphane

    2016-01-01

    We demonstrate the operation of an all-optical buffer based on temporal cavity solitons stored in a nonlinear passive fiber ring resonator. Unwanted acoustic interactions between neighboring solitons are suppressed by modulating the phase of the external laser driving the cavity. A new locking scheme is presented that allows the buffer to operate with an arbitrarily large number of cavity solitons in the loop. Experimentally, we are able to demonstrate the storage of 4536 bits of data, written all-optically into the fiber ring at 10 Gb/s, for 1 minute.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-09-01

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

  15. Hybrid vertical cavity laser

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2010-01-01

    A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.......A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide....

  16. Dual-cavity Nd:YAG laser with Laguerre-Gaussian (LG0n) mode output

    Science.gov (United States)

    Kim, D. J.; Kim, J. W.

    2017-01-01

    Direct excitation of an arbitrary Laguerre-Gaussian (LG0n) mode with helical wavefronts in a diode-end-pumped solid state laser employing a dual-cavity configuration is reported. Through simple adjustments of the intra-cavity apertures in the dual-cavity laser configuration, the spatial gain distribution and the cavity loss could be optimized for the targeted LG0 n mode. This approach has been applied to a diode-pumped Nd: YAG laser to achieve selective lasing of the LG01, LG02, and LG03 modes. Also, an optical vortex laser beam was produced directly from the laser resonator by determining the wavefront handedness of each LG mode output using an intra-cavity etalon. The prospects of further power scaling and laser performance improvements will be discussed.

  17. Optical frequency combs generated by four-wave mixing in a dual wavelength Brillouin laser cavity

    Directory of Open Access Journals (Sweden)

    Qing Li

    2017-07-01

    Full Text Available We propose and demonstrate the generation of optical frequency combs via four-wave mixing in a dual wavelength Brillouin laser cavity. When pumped by two continuous-wave lasers with a varied frequency separation, dual wavelength Brillouin lasers with reduced linewidth and improved optical signal to noise ratios are generated in a direction opposite to the pump laser. Simultaneously, cavity-enhanced cascaded four-wave mixing between dual wavelength Brillouin lasers occurs in the laser cavity, causing the generation of broadband optical frequency combs with step tunable mode spacing from 40 to 1300 GHz. Compared to the cavity-less case, the number of the comb lines generated in the dual wavelength Brillouin laser cavity is increased by ∼38 times.

  18. On JB-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin CHEN

    2007-01-01

    A ring R is a QB-ring provided that aR + bR = R with a, b ∈ R implies that there exists a y ∈ R such that a+by ∈ R-1q. It is said that a ring R is a JB-ring provided that R/J(R) is a QB-ring, where J(R) is the Jacobson radical of R. In this paper, various necessary and sufficient conditions, under which a ring is a JB-ring, are established. It is proved that JB-rings can be characterized by pseudo-similarity. Furthermore, the author proves that R is a J B-ring iff so is R/J(R)2.

  19. Surface explosion cavities

    CERN Document Server

    Benusiglio, Adrien; Clanet, Christophe

    2012-01-01

    We present a fluid dynamics video on cavities created by explosions of firecrackers at the water free surface. We use three types of firecrackers containing 1, 1.3 and 5 g of flash powder. The firecrackers are held with their center at the surface of water in a cubic meter pool. The movies are recorded from the side with a high-speed video camera. Without confinement the explosion produces an hemispherical cavity. Right after the explosion this cavity grows isotropically, the bottom then stops while the sides continue to expand. In the next phase the bottom of the cavity accelerates backwards to the surface. During this phase the convergence of the flow creates a central jet that rises above the free surface. In the last part of the video the explosion is confined in a vertical open tube made of glass and of centimetric diameter. The explosion creates a cylindrical cavity that develops towards the free end of the tube. Depending on the charge, the cavity can either stop inside the tube or at its exit, but nev...

  20. The Superconducting TESLA Cavities

    CERN Document Server

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  1. 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.

  2. On semi ring bornologies

    Science.gov (United States)

    Imran, A. N.; Rakhimov, I. S.; Husain, Sh. K. Said

    2016-06-01

    Our main focus in this work is to introduce new structure bornological semi rings. This generalizes the theory of algebraic semi rings from the algebraic setting to the framework of bornological sets. We give basic properties for this new structure. As well as, We study the fundamental construction of bornological semi ring as product, inductive limits and projective limits and their extensions on bornological semi ring. Additionally, we introduce the category of bornological semi rings and study product and pullback (fiber product) in the category of bornological semi rings.

  3. 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.

  4. 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.

  5. 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.

  6. Displacement-noise-free gravitational-wave detection with two Fabry-Perot cavities

    CERN Document Server

    Rakhubovsky, Andrey A

    2008-01-01

    We propose two detuned Fabry-Perot cavities, each pumped through both the mirrors, positioned in line as a toy model of the gravitational-wave (GW) detector free from displacement noise of the test masses. It is demonstrated that the noise of cavity mirrors can be completely excluded in a proper linear combination of the cavities output signals. This model is illustrated by a simplified round trip model (without Fabry-Perot cavities). We show that in low-frequency region the obtained displacement-noise-free response signal is stronger than the one of the interferometer recently proposed by S.Kawamura and Y.Chen.

  7. Controllable coupling of distributed qubits within a microtoroidal cavity network

    Science.gov (United States)

    Hu, C.; Xia, Y.; Song, J.

    2012-05-01

    We propose a scheme to control the coupling between two arbitrary atoms scattered within a quantum network composed of microtoroidal cavities linked by a ring-fibre. The atom-atom effective couplings are induced by pairing of off-resonant Raman transitions. The couplings can be arbitrarily controlled by adjusting classical fields. Compared with the previous scheme [S.B. Zheng, C.P. Yang, F. Nori, Phys. Rev. A 82, 042327 (2010)], the present scheme uses microtoroidal cavities with higher coupling efficiency than Fabry-Perot cavities. Furthermore, the scheme is not only suitable for the short-fibre limit, but also for multiple fibre modes. The added fibre modes can play a positive role, especially when the coupling rate between cavity-mode and fibre-mode is not large. In addition, a wider frequency domain of fibre modes can be used in this scheme.

  8. A Laser-Diode End-Pumped Nd:YVO4 Slab Laser at 1342 nm

    Institute of Scientific and Technical Information of China (English)

    YAN Ying; ZHANG Heng-Li; LIU Yang; XING Ji-Chuan; XIN Jian-Guo

    2009-01-01

    A laser-diode end-pumped Nd:YV04 slab laser with a fiat-concave stable cavity at 1342nm is demonstrated. Under the pumping power of 92 W, a cw laser of output 17.8 W is obtained with the slope efficiency of 25.6%.

  9. Plasma processing of superconducting radio frequency cavities

    Science.gov (United States)

    Upadhyay, Janardan

    The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb SRF cavities. In the process of developing plasma etching technology, an apparatus was built and a method was developed to plasma etch a single cell Pill Box cavity. The plasma characterization was done with the help of optical emission spectroscopy. The Nb etch rate at various points of this cavity was measured before processing the SRF cavity. Cylindrical ring-type samples of Nb placed on the inner surface of the outer wall were used to measure the dependence of the process parameters on plasma etching. The measured etch rate dependence on the pressure, rf power, dc bias, temperature, Cl2 concentration and diameter of the inner electrode was determined. The etch rate mechanism was studied by varying the temperature of the outer wall, the dc bias on the inner electrode and gas conditions. In a coaxial plasma reactor, uniform plasma etching along the cylindrical structure is a challenging task due to depletion of the active radicals along the gas flow direction. The dependence of etch rate uniformity along the cylindrical axis was determined as a function of process parameters. The formation of dc self-biases due to surface area asymmetry in this type of plasma and its variation on the pressure, rf power and gas composition was measured. Enhancing the surface area of the inner electrode to reduce the

  10. Coupled resonator vertical cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Chow, W.W.; Hou, H.Q.; Geib, K.M.; Hammons, B.E.

    1998-01-01

    The monolithic integration of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. The authors report the first electrically injected coupled resonator vertical-cavity laser diode and demonstrate novel characteristics arising from the cavity coupling, including methods for external modulation of the laser. A coupled mode theory is used model the output modulation of the coupled resonator vertical cavity laser.

  11. 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...

  12. 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.

  13. The implantable peritoneal pump--a patient's perspective.

    Science.gov (United States)

    Witkowski, Christopher J; Saudek, Christopher

    2008-07-01

    A participant in a study of implantable insulin pump therapy recounts his experiences with on-and-off use of the pump over the past 18 years. Christopher Witkowski, 55, first had a pump implanted in 1990. Despite occasional difficulties over the years, Witkowski reports that his overall experience has been extremely positive. With delivery of insulin directly into the peritoneal cavity, he feels better, has more flexibility in eating, and experiences fewer insulin reactions. Witkowski expresses disappointment that the manufacturer of the pump, Medtronic, no longer plans to seek Food and Drug Administration approval for this therapy. Witkowski expresses his hope that research on the device will continue, believing that this therapy could be of benefit to millions of diabetes patients. This article is accompanied by a detailed description of the pump refill procedure by Dr. Christopher Saudek of Johns Hopkins University, current leader of the ongoing research study.

  14. High brightness diode-pumped organic solid-state laser

    CERN Document Server

    Zhao, Zhuang; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-01-01

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  15. High brightness diode-pumped organic solid-state laser

    Science.gov (United States)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-02-01

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  16. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  17. 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 ...

  18. The properties of squeezed optical states created in lossy cavities

    CERN Document Server

    Seifoory, Hossein; Dignam, Marc M; Sipe, J E

    2016-01-01

    We investigate theoretically the properties of squeezed states generated using degenerate parametric down conversion in lossy cavities. We show that the Lindblad master equation, which governs the evolution of this system, has as its solution a squeezed thermal state with an effective temperature and squeezing parameter that depends on time. We derive analytical solutions for the time-evolution of quadrature noise, thermal photon number, squeezing parameter, and total photon number under different pumping regimes. We also find the steady state limits of the quadrature noises and discuss the $ g^{(2)} $ factor of the generated light inside the cavity in the steady state.

  19. Birth Control Ring

    Science.gov (United States)

    ... Right Sport for You Healthy School Lunch Planner Birth Control Ring KidsHealth > For Teens > Birth Control Ring Print A A A What's in ... español Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ...

  20. On Weakly Semicommutative Rings*

    Institute of Scientific and Technical Information of China (English)

    CHEN WEI-XING; CUI SHU-YING

    2011-01-01

    A ring R is said to be weakly scmicommutative if for any a, b ∈ R,ab = 0 implies aRb C_ Nil(R), where Nil(R) is the set of all nilpotcnt elements in R.In this note, we clarify the relationship between weakly semicommutative rings and NI-rings by proving that the notion of a weakly semicommutative ring is a proper generalization of NI-rings. We say that a ring R is weakly 2-primal if the set of nilpotent elements in R coincides with its Levitzki radical, and prove that if R is a weakly 2-primal ring which satisfies oα-condition for an endomorphism α of R (that is, ab = 0 (←→) aα(b) = 0 where a, b ∈ R) then the skew polynomial ring R[π; αα]is a weakly 2-primal ring, and that if R is a ring and I is an ideal of R such that I and R/I are both weakly semicommutative then R is weakly semicommutative.Those extend the main results of Liang et al. 2007 (Taiwanese J. Math., 11(5)(2007),1359-1368) considerably. Moreover, several new results about weakly semicommutative rings and NI-rings are included.

  1. Fibre-coupled red diode-pumped Alexandrite TEM00 laser with single and double-pass end-pumping

    Science.gov (United States)

    Arbabzadah, E. A.; Damzen, M. J.

    2016-06-01

    We report the investigation of an Alexandrite laser end-pumped by a fibre-coupled red diode laser module. Power, efficiency, spatial, spectral, and wavelength tuning performance are studied as a function of pump and laser cavity parameters. It is the first demonstration, to our knowledge, of greater than 1 W power and also highest laser slope efficiency (44.2%) in a diode-pumped Alexandrite laser with diffraction-limited TEM00 mode operation. Spatial quality was excellent with beam propagation parameter M 2 ~ 1.05. Wavelength tuning from 737-796 nm was demonstrated using an intracavity birefringent tuning filter. Using a novel double pass end-pumping scheme to get efficient absorption of both polarisation states of the scrambled fibre-delivered diode pump, a total output coupled power of 1.66 W is produced in TEM00 mode with 40% slope efficiency.

  2. A scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Wu Tao; Ye Liu; Ni Zhi-Xiang

    2006-01-01

    In this paper, we propose a scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics (QED). This scheme, which has a successful probability of 100 percent, does not require Bell-state measurement and performing any operations to reconstruct an initial state. Meanwhile, the scheme only involves atomfield interaction with a large detuning and does not require the transfer of quantum information between the atoms and cavity. Thus the scheme is insensitive to the cavity field states and cavity decay. This scheme can also be extended to transfer ring an entangled state of n-atom.

  3. LEP superconducting accelerating cavity module

    CERN Multimedia

    With its 27-kilometre circumference, the Large Electron-Positron (LEP) collider was – and still is – the largest electron-positron accelerator ever built. The excavation of the LEP tunnel was Europe’s largest civil-engineering project prior to the Channel Tunnel. Three tunnel-boring machines started excavating the tunnel in February 1985 and the ring was completed three years later. In its first phase of operation, LEP consisted of 5176 magnets and 128 accelerating cavities. CERN’s accelerator complex provided the particles and four enormous detectors, ALEPH, DELPHI, L3 and OPAL, observed the collisions. LEP was commissioned in July 1989 and the first beam circulated in the collider on 14 July. The collider's initial energy was chosen to be around 91 GeV, so that Z bosons could be produced. The Z boson and its charged partner the W boson, both discovered at CERN in 1983, are responsible for the weak force, which drives the Sun, for example. Observing the creation and decay of the short-lived Z boson w...

  4. 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.

  5. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  6. Acceleration for the mu-Storage Ring Neutrino Source

    OpenAIRE

    Neuffer, David

    2000-01-01

    A muon storage ring neutrino source uses an induction linac for muon capture, a 200 MHz copper cavity system for cooling, and 200 and 400 MHz superconducting rf systems for acceleration to a final energy of up to 50 GeV. These systems and their requirements are discussed in this paper.

  7. Dispersion-managed semiconductor mode-locked ring laser.

    Science.gov (United States)

    Resan, Bojan; Archundia, Luis; Delfyett, Peter J; Alphonse, Gerard

    2003-08-01

    A novel breathing-mode external sigma-ring-cavity semiconductor mode-locked laser is developed. Intracavity pulse compression and stretching produce linearly chirped pulses with an asymmetric exponential temporal profile. External dispersion compensation reduces the pulse duration to 274 fs (within 10% of the bandwidth limit).

  8. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1998-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  9. Stable CW Single-Mode Photonic Crystal Fiber DFB Ring Laser

    Institute of Scientific and Technical Information of China (English)

    Kevin Cook; John Canning; John Holdsworth; Chris Dewhurst

    2008-01-01

    We demonstrate stable single-mode CW operation of a DFB ring laser based on Er3+ doped photonics crystal fiber (PCF). The incorporation of a ring cavity allows one single mode to lase and also suppresses the unwanted effect of self-pulsing. Such a narrow linewidth source in PCF has great potential in spectroscopy.

  10. Physics of quantum rings

    CERN Document Server

    Fomin, Vladimir M

    2013-01-01

    This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is po

  11. Envelopes of Commutative Rings

    Institute of Scientific and Technical Information of China (English)

    Rafael PARRA; Manuel SAOR(I)N

    2012-01-01

    Given a significative class F of commutative rings,we study the precise conditions under which a commutative ring R has an F-envelope.A full answer is obtained when.F is the class of fields,semisimple commutative rings or integral domains.When F is the class of Noetherian rings,we give a full answer when the Krull dimension of R is zero and when the envelope is required to be epimorphic.The general problem is reduced to identifying the class of non-Noetherian rings having a monomorphic Noetherian envelope,which we conjecture is the empty class.

  12. RING PROXY SIGNATURES

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Proxy signatures have been used to enable the transfer of digital signing power within some context and ring signatures can be used to provide the anonymity of a signer. By combining the functionalities of proxy signatures and ring signatures, this paper introduces a new concept, named ring proxy signature, which is a proxy signature generated by an anonymous member from a set of potential signers. The paper also constructs the first concrete ring proxy signature scheme based on the provably secure Schnorr's signatures and two ID-based ring proxy signature schemes. The security analysis is provided as well.

  13. Effect of parametric variation on generation and enhancement of chaos in erbium-doped fiber-ring lasers

    Science.gov (United States)

    Ali, Syed Zafar; Islam, Muhammad Khawar; Zafrullah, Muhammad

    2010-10-01

    The simulation and numerical analysis of erbium-doped fiber-ring lasers for generation and enhancement of chaos is presented. The degree of chaos determines the level of security in chaotic optical communication systems. Various parameters such as pump power, modulation index, modulation frequency, decay rate, and cavity gain can be varied as a control in producing higher degree optical chaos. The effect of each pertinent model parameter is analyzed in time-expanded mode using a phase plot direct-observation method and time series analysis of the time domain wave form by calculating its Lyapunov exponents. The mathematical and numerical analysis of the generated chaos helps in generalizing the trend through variation of cavity parameters and driving conditions in achieving a relatively higher degree of chaos. These trends help in optimizing various parameters for generation of new sequences of optical chaos in realizing better security. To gain an insight into chaotic signatures, the width and height of individual pulses, relationship of their time periods, gain quenching, shape, formation of bunches, and humps of the chaotic wave forms are also analyzed. The study of individual and cumulative behavior of all the parameters in enhancing optical chaos leads toward a reliable development in designing secure communication systems.

  14. The next linear collider damping ring complex

    Energy Technology Data Exchange (ETDEWEB)

    Corlett,J.; Atkinson,D.; De Santis,S.; Hartman, N.; Kennedy, K.; Li, D.; Marks, S.; Minamihara, Y.; Nishimura, H.; Pivi, M.; Reavill, D.; Rimmer, R.; Schlueter, R.; Wolski, A.; Anderson,S.; McKee,B.; Raubenheimer, T.; Ross, M.; Sheppard, J.C.

    2001-06-12

    We report progress on the design of the Next Linear Collider (NLC) Damping Rings complexes. The purpose of the damping rings is to provide low emittance electron and positron bunch trains to the NLC linacs, at a rate of 120 Hz. As an option to operate at the higher rate of 180 Hz, two 1.98 GeV main damping rings per beam are proposed, and one positron pre-damping ring. The main damping rings store up to 0.8 amp in 3 trains of 190 bunches each and have normalized extracted beam emittances {gamma}{var_epsilon}x = 3 mm-mrad and {gamma}{var_epsilon}y = 0.02 mm-mrad. The optical designs, based on a theoretical minimum emittance lattice (TME), are described, with an analysis of dynamic aperture and non-linear effects. Key subsystems and components are described, including the wiggler, the vacuum systems and photon stop design, and the higher-order-mode damped RF cavities. Impedance and instabilities are discussed.

  15. Continuous variable entanglement in a coherently pumped correlated emission laser

    Energy Technology Data Exchange (ETDEWEB)

    Tesfa, Sintayehu [Physics Department, Addis Ababa University, PO Box 1176, Addis Ababa (Ethiopia)], E-mail: sint_tesfa@yahoo.com

    2008-03-14

    Analysis of the effects of external pumping on the quantum features of cavity radiation of the two-photon correlated emission laser is presented. It turns out that the pumping process induces the atomic coherence responsible for the entanglement of the cavity radiation as well as the correlation between the photon numbers belonging to different modes, despite the arising vacuum fluctuations. The photon number correlation is found to be very close to 2 where the entanglement is relatively better. Moreover, the mean number of photon pairs decreases with the amplitude of the driving radiation which is one of the practical limitations associated with the pumping mechanism. It is also shown that the mean photon number of the radiation in mode b is less than one-third of that in mode a.

  16. Saturn's largest ring.

    Science.gov (United States)

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  17. Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model

    DEFF Research Database (Denmark)

    Poulsen, Christian; Sejka, Milan

    1993-01-01

    A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing...

  18. Using active resonator impedance matching for shot-noise limited, cavity enhanced amplitude modulated laser absorption spectroscopy.

    Science.gov (United States)

    Chow, Jong H; Littler, Ian C M; Rabeling, David S; McClelland, David E; Gray, Malcolm B

    2008-05-26

    We introduce a closed-loop feedback technique to actively control the coupling condition of an optical cavity, by employing amplitude modulation of the interrogating laser. We show that active impedance matching of the cavity facilitates optimal shot-noise sensing performance in a cavity enhanced system, while its control error signal can be used for intra-cavity absorption or loss signal extraction. We present the first demonstration of this technique with a fiber ring cavity, and achieved shot-noise limited loss sensitivity. We also briefly discuss further use of impedance matching control as a tool for other applications.

  19. The contraceptive vaginal ring.

    Science.gov (United States)

    Edwardson, Jill; Jamshidi, Roxanne

    2010-03-01

    The contraceptive vaginal ring offers effective contraception that is self-administered, requires less frequent dosing than many other forms of contraception, and provides low doses of hormones. NuvaRing (Organon, Oss, The Netherlands), the only contraceptive vaginal ring approved for use in the United States, contains etonogestrel and ethinyl estradiol. It is inserted into the vagina for 3 weeks, followed by a 1-week ring-free period, and works by inhibiting ovulation. Most women note a beneficial effect on bleeding profiles and are satisfied with NuvaRing. Commonly reported adverse events include vaginitis, leukorrhea, headaches, and device-related events such as discomfort. Serious adverse events are rare. In Chile and Peru, progesterone-only vaginal contraceptive rings are available for nursing women. Studies are ongoing examining new formulations of vaginal contraceptive rings.

  20. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    Energy Technology Data Exchange (ETDEWEB)

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.