WorldWideScience

Sample records for cavity frequency doubling

  1. Intracavity frequency-doubled green vertical external cavity surface emitting laser

    Institute of Scientific and Technical Information of China (English)

    Yanrong Song; Peng Zhang; Xinping Zhang; Boxia Yan; Yi Zhou; Yong Bi; Zhigang Zhang

    2008-01-01

    @@ An intracavity frequency-doubled vertical external cavity surface emitting laser (VECSEL) with green light is demonstrated. The fundamental frequency laser cavity consists of a distributed Bragg reflector (DBR) of the gain chip and an external mirror. A 12-mW frequency-doubled output has been reached at 540 nm with a nonlinear crystal LBO when the fundamental frequency output is 44 mW at 1080 nm. The frequency doubling efficiency is about 30%.

  2. Quantum frequency doubling based on tripartite entanglement with cavities

    Science.gov (United States)

    Juan, Guo; Zhi-Feng, Wei; Su-Ying, Zhang

    2016-02-01

    We analyze the entanglement characteristics of three harmonic modes, which are the output fields from three cavities with an input tripartite entangled state at fundamental frequency. The entanglement properties of the input beams can be maintained after their frequencies have been up-converted by the process of second harmonic generation. We have calculated the parametric dependences of the correlation spectrum on the initial squeezing factor, the pump power, the transmission coefficient, and the normalized analysis frequency of cavity. The numerical results provide references to choose proper experimental parameters for designing the experiment. The frequency conversion of the multipartite entangled state can also be applied to a quantum communication network. Project supported by the National Natural Science Foundation of China (Grant No. 91430109), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111401110004), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2014011005-3).

  3. Cold Testing Of A Radial Extraction Output Cavity For A Frequency-doubling Gyroklystron

    CERN Document Server

    Bharathan, K

    2004-01-01

    Research in the University of Maryland Gyroklystron program has centered around the development of a 17.136 GHz gyroklystron, that combines the gyrotron mechanism with the ballistic bunching of klystrons to produce a high power, high gain amplifier. The current tube is a 4- cavity (input, buncher, penultimate and output) coaxial, frequency doubling system that will be used as a driver for the Haimson Research Corporation (HRC) accelerator structure. This thesis presents the design, simulation, optimization, cold test methodology and performance data of a proposed radial extraction output cavity in which the microwave energy is extracted through an inner coaxial conductor in the TE01 circular mode. The positioning of dielectrics in the drift spaces and the effect of axial and radial misalignments between the inner and outer walls of the cavity were studied at depth and quantified. One advantage of this topology is that it reduces the size and complexity of the output waveguide chain otherwise needed to convert...

  4. External-cavity frequency doubling of a 5-W 756-nm injection-locked Ti:sapphire laser.

    Science.gov (United States)

    Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

    2008-03-31

    We have developed a 5-W 756-nm injection-locked Ti:sapphire laser and frequency-doubled it in an external enhancement cavity for the generation of watt-level 378-nm single-frequency radiation, which is essential for isotope-selective optical pumping of thallium atoms. With a lithium triborate (LBO) crystal in the enhancement cavity, 1.1 W at 378 nm was coupled out from the cavity. Such results are to our knowledge the highest powers of continuous-wave single-frequency radiation generated from a Ti:sapphire laser and its frequency doubling. PMID:18542585

  5. Frequency doubled femtosecond Ti:sapphire laser with an assisted enhancement cavity

    Science.gov (United States)

    Jin-Wei, Zhang; Hai-Nian, Han; Lei, Hou; Long, Zhang; Zi-Jiao, Yu; De-Hua, Li; Zhi-Yi, Wei

    2016-01-01

    We report an enhancement cavity for femtosecond Ti:sapphire laser at the repetition rate of 170 MHz. An enhancement factor of 24 is obtained when the injecting pulses have an average power of 1 W and a pulse duration of 80 fs. By placing a BBO crystal at the focus of the cavity, we obtain a 392-mW intracavity doubled-frequency laser, corresponding to a conversion efficiency of 43%. The output power has a long-term stability with a root mean square (RMS) of 0.036%. Project supported by the National Basic Research Program of China (Grant Nos. 2013CB922401 and 2012CB821304) and the National Natural Science Foundation of China (Grant No. 61378040).

  6. A novel approach to a PPM-modulated frequency-doubled electro-optic cavity-dumped Nd:YAG laser

    Science.gov (United States)

    Robinson, D. L.

    1989-01-01

    A technique which can provide frequency doubling, with high efficiency, while cavity dumping a laser for pulse position M-ary modulation while being used for an optical communication link is discussed. This approach uses a secondary cavity that provides feedback of the undoubled fundamental light, which is normally lost, into the primary cavity to be recirculated and frequency doubled. Specific operations of the electrooptic modulator and frequency-doubling crystal are described along with the overall modulation scheme and experimental setup.

  7. Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm.

    Science.gov (United States)

    Bek, Roman; Baumgärtner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbäck, Thomas; Jetter, Michael; Michler, Peter

    2015-07-27

    We present a passively mode-locked semiconductor disk laser (SDL) emitting at 650nm with intra-cavity second harmonic generation to the ultraviolet (UV) spectral range. Both the gain and the absorber structure contain InP quantum dots (QDs) as active material. In a v-shaped cavity using the semiconductor samples as end mirrors, a beta barium borate (BBO) crystal is placed in front of the semiconductor saturable absorber mirror (SESAM) for pulsed UV laser emission in one of the two outcoupled beams. Autocorrelation (AC) measurements at the fundamental wavelength reveal a FWHM pulse duration of 1.22ps. With a repetition frequency of 836MHz, the average output power is 10mW per beam for the red emission and 0.5mW at 325nm.

  8. Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm.

    Science.gov (United States)

    Bek, Roman; Baumgärtner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbäck, Thomas; Jetter, Michael; Michler, Peter

    2015-07-27

    We present a passively mode-locked semiconductor disk laser (SDL) emitting at 650nm with intra-cavity second harmonic generation to the ultraviolet (UV) spectral range. Both the gain and the absorber structure contain InP quantum dots (QDs) as active material. In a v-shaped cavity using the semiconductor samples as end mirrors, a beta barium borate (BBO) crystal is placed in front of the semiconductor saturable absorber mirror (SESAM) for pulsed UV laser emission in one of the two outcoupled beams. Autocorrelation (AC) measurements at the fundamental wavelength reveal a FWHM pulse duration of 1.22ps. With a repetition frequency of 836MHz, the average output power is 10mW per beam for the red emission and 0.5mW at 325nm. PMID:26367654

  9. Diode-pumped Q-switched Extra-cavity Frequency-doubled Nd: YVO4/KTP Green Laser

    Institute of Scientific and Technical Information of China (English)

    YANG Ji-min; LIU Jie; HE Jing-liang

    2005-01-01

    A diode-pumped acousto-optical(A-O) Q-switched extra-cavity frequency-doubled Nd: YVO4/KTP (KTiOPO4) green laser formed with a simple plane-plane cavity has been demonstrated. With the incident pump power of 12. 7 W, A-O Q-switched average output power at 1 064 nm was 3.81 W with a duration of 25 ns at a repetition rate of 20 kHz, extra-cavity frequency doubling with KTP as the nonlinear crystal yielded the maximum output power of 1. 92 W at 532 nm, the corresponding optical conversion efficiency from 1 064 nm to 532 nm light is 50.4%. The continuous-wave(CW) laser properties of diodepumped Nd: YVO4 crystal operating at 1 064 nm have been studied. With the incident pump power of 25 W,the maximum CW output power of 13.81 W was obtained with the corresponding optical conversion efficiency of 55.24%.

  10. Threshold for strong thermal dephasing in periodically poled KTP in external cavity frequency doubling

    DEFF Research Database (Denmark)

    Lundeman, Jesper Holm; Jensen, Ole Bjarlin; Andersen, Peter E.;

    2009-01-01

    We present a measurement series of the efficiency of periodically poled KTP used for second-harmonic generation in an external phase-locked cavity. Due to the high absorption (0.01 cm^−1) in the PPKTP crystal at the pump wavelength a strong thermal dephasing of the periodically poled grating is o...

  11. Cavity-enhanced frequency doubling from 795nm to 397.5nm ultra-violet coherent radiation with PPKTP crystals in the low pump power regime.

    Science.gov (United States)

    Wen, Xin; Han, Yashuai; Bai, Jiandong; He, Jun; Wang, Yanhua; Yang, Baodong; Wang, Junmin

    2014-12-29

    We demonstrate a simple, compact and cost-efficient diode laser pumped frequency doubling system at 795 nm in the low power regime. In two configurations, a bow-tie four-mirror ring enhancement cavity with a PPKTP crystal inside and a semi-monolithic PPKTP enhancement cavity, we obtain 397.5nm ultra-violet coherent radiation of 35mW and 47mW respectively with a mode-matched fundamental power of about 110mW, corresponding to a conversion efficiency of 32% and 41%. The low loss semi-monolithic cavity leads to the better results. The constructed ultra-violet coherent radiation has good power stability and beam quality, and the system has huge potential in quantum optics and cold atom physics. PMID:25607194

  12. 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.

  13. 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.

  14. A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

    Science.gov (United States)

    Rakhman, A.; Hafez, M.; 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.

    2016-06-01

    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:LiNbO3 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.

  15. LEP Radio Frequency Copper Cavities

    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.

  16. Frequency Tuning for a DQW Crab Cavity

    CERN Document Server

    Verdú-Andrés, Silvia; Ben-Zvi, Ilan; Calaga, Rama; Capatina, Ofelia; Leuxe, Raphael; Skaritka, John; Wu, Qiong; Xiao, Binping; Zanoni, Carlo

    2016-01-01

    The nominal operating frequency for the HL-LHC crab cavities is 400.79 MHz within a bandwidth of ±60kHz. Attaining the required cavity tune implies a good understanding of all the processes that influence the cavity frequency from the moment when the cavity parts are being fabricated until the cavity is installed and under operation. Different tuning options will be available for the DQW crab cavity of LHC. This paper details the different steps in the cavity fabrication and preparation that may introduce a shift in the cavity frequency and introduces the different tuning methods foreseen to bring the cavity frequency to meet the specifications.

  17. Optimization of a lasertron double output cavity

    International Nuclear Information System (INIS)

    Double output cavities have been used experimentally to increase the efficiency of high-power klystrons. We have used particle-in-cell simulations with the 2 + 1/2 dimensional code MASK to optimize the design of double output cavities for the lasertron under development at SLAC. We discuss design considerations for double output cavities (e.g., optimum choice of voltages and phases, efficiency, wall interception, breakdown). We describe how one calculates the cavity impedance matrix from the gap voltages and phases. Some results of the effect of varying voltage, perveance, and pulse are reported

  18. Efficient intracavity frequency doubling of an Yb-doped fiber laser using an internal resonant enhancement cavity

    OpenAIRE

    Cieslak, R.; Sahu, J.K.; Clarkson, W. A.

    2010-01-01

    We describe a simple approach for efficient generation of visible light in high-power continuous-wave fiber lasers via second harmonic generation in an internal resonant cavity. Preliminary results for a cladding-pumped Yb fiber laser are presented.

  19. 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.

  20. Properties of pulse single-frequency laser and extra-cavity double frequency green laser%脉冲单频 Nd∶YVO4激光器及其倍频输出特性研究

    Institute of Scientific and Technical Information of China (English)

    董磊; 刘欣悦; 陈浩

    2015-01-01

    In order to manufacture a pulse single-frequency laser with master oscillator power amplifier( MO-PA) structure used for laser coherence imaging, the properties of acousto-optic Q-switched pulse single-fre-quency 1 064 nm laser used as MOPA laser seed, and properties of extra-cavity double frequency green laser were studied in the paer.1 064 nm pulse laser output with more than 20 ns pulse width was realized by means of acousto-optics Q-switch, and single-frequency running was realized by means of loop cavity and etalons with different thickness.The linewidth of 1 064 nm and 532 nm pulse lasers were studied.The experiment results show that there is almost complete coherence in all of the pulse width;1 064 nm pulse single-frequency laser with 28 nm pulse width and 6 .5 kW peak power and 532 nm laser with 20 ns pulse width and 0.5 kW peak power are obtained respectively.The efficiency of extra-cavity double-frequency is about 5.6%.The effect of laser pulse reduction by extra-cavity double-frequency is also validated by experiments.%为了研制激光干涉成像所需的主振荡功率放大( MOPA)结构脉冲单频激光器,本文完成MOPA激光器的种子源即声光调Q脉冲单频1064 nm激光器的特性研究,同时完成种子源腔外倍频绿光特性研究。脉冲单频激光器采用声光调Q模块实现脉宽约20 ns的1064 nm脉冲激光输出,采用环形腔设计并采用一组不同厚度的标准具实现单纵模运转。实验研究基频1064 nm和倍频532 nm激光脉冲的线宽,得出在全脉宽范围内都具有较高时间相干性的结论。实验分别获得脉宽约28 ns峰值功率约6.5 kW的1064 nm脉冲单频激光和脉宽约20 ns、峰值功率约0.5 kW的532 nm脉冲单频激光,腔外倍频效率为5.6%。实验同时也验证了腔外倍频的激光脉宽压缩效应。

  1. Intra-cavity frequency-doubled Cr:LiCAF laser with 265 mW continuous-wave blue (395-405 nm) output

    Science.gov (United States)

    Demirbas, Umit; Uecker, Reinhard; Klimm, Detlef; Sumpf, Bernd; Erbert, Götz

    2014-06-01

    We describe continuous-wave (cw) intracavity frequency-doubling experiments performed with a Cr:LiCAF laser. The Cr:LiCAF crystal is home-grown and had passive losses below 0.15% per cm. The laser is pumped by two recently-developed high-brightness tapered diodes, providing a total pump power of 2 W at 680 nm. The Cr:LiCAF laser generated up to 585 mW of cw output power around 800 nm with 43% slope efficiency at an absorbed pump power of 1.4 W. The low passive losses of the crystal enabled storage of up to 380 W of intracavity laser power using a 0.07% transmitting output coupler, demonstrating suitability of Cr:LiCAF gain media for intracavity nonlinear conversion experiments. By performing intracavity frequency doubling with a BBO crystal, cw second-harmonic powers as high as 265 mW around 400 nm have been realized with optical-to-optical conversion efficiencies as high as 13.3%. To our knowledge, these are the highest cw frequency-doubled laser powers and conversion efficiencies obtained from Cr:Colquiriites to date. Moreover, obtained efficiencies are superior compared to what have been achieved with similar Ti:Sapphire systems, due to lower passive losses of Cr:LiCAF crystal. These results demonstrate the appropriateness of Cr:LiCAF gain media as a high-power tunable cw radiation generator in 375-435 nm region.

  2. Nb3Sn for Radio Frequency Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Godeke, A.

    2006-12-18

    In this article, the suitability of Nb3Sn to improve theperformance of superconducting Radio-Frequency (RF)cavities is discussed.The use of Nb3Sn in RF cavitiesis recognized as an enabling technology toretain a veryhigh cavity quality factor (Q0) at 4.2 K and tosignificantly improve the cavity accelerating efficiency per unitlength(Eacc). This potential arises through the fundamental properties ofNb3Sn. The properties that are extensively characterized in theliterature are, however, mainly related to improvements in currentcarrying capacity (Jc) in the vortex state. Much less is available forthe Meissner state, which is of key importance to cavities. Relevantdata, available for the Meissner state is summarized, and it is shown howthis already validates the use of Nb3Sn. In addition, missing knowledgeis highlighted and suggestions are given for further Meissner statespecific research.

  3. Frequency doubling crystals

    Science.gov (United States)

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  4. 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

  5. Striped-double cavity fabry-perot interferometers using both glass and air cavities

    Energy Technology Data Exchange (ETDEWEB)

    Perry, S; Steinmetz, L

    1998-07-08

    We have used piezo-driven Fabry-Perot interferometers in the past far many continuous velocity-time measurements of fast moving surfaces. In order to avoid the annoying drift of some of these devices, we have developed and used inexpensive, solid glass, striped etalons with lengths up to 64 mm. Usable apertures are 35 mm by 80 mm with a finess of 25. A roundabout technique was devised for double cavity operation. We built a passive thermal housing for temperature stability, with tilt and height adjustments. We have also developed and used our first fixed etalon air-spaced cavity with a rotatable glass double- cavity insert. The rotation allows the referee cavity fractional order to be adjusted separately from that of the main cavity. It needs very little thermal protection, and eliminates the need for a roundabout scheme for double cavity operation, but is more costly than the solid glass version I

  6. 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.

  7. 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

    in the broad wavelength range from 1049 nm to 1093 nm and the beam propagation factor is improved from M2 = 2.8 to below 1.1. The laser frequency is automatically locked to the cavity resonance frequency using optical feedback. Furthermore, we show that this adaptive external cavity approach leads to efficient......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...

  8. Design, prototyping and testing of a compact superconducting double quarter wave crab cavity

    CERN Document Server

    Xiao, Binping; Belomestnykh, Sergey; Ben-Zvi, Ilan; Calaga, Rama; Cullen, Chris; Capatina, Ofelia; Hammons, Lee; Li, Zenghai; Marques, Carlos; Skaritka, John; Verdú-Andres, Silvia; Wu, Qiong

    2015-01-01

    A novel design of superconducting Crab Cavity was proposed and designed at Brookhaven National Laboratory. The new cavity shape is a Double Quarter Wave or DQWCC. After fabrication and surface treatments, the niobium proof-of-principle cavity was cryogenically tested in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service for the Large Hadron Collider luminosity upgrade. The electromagnetic properties of the cavity are also well matched for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the requirement for a crab cavity in the future High Luminosity LHC of 3.34 MV. In this paper we present the design, prototyping and test results of the DQWCC.

  9. Photon-photon interactions with inner coupled double-cavity

    Institute of Scientific and Technical Information of China (English)

    Lai Wen-Xi; Li Hong-Cai; Yang Rong-Can

    2008-01-01

    This paper describes the interaction between two spatial modes of the optical fields with a single atom trapped inner coupled double-cavity.Theoretical derivation and numerical simulation with the experimental available parameters show that photon-photon switching and π phase shift of single photons may be achieved with current experimental technology.As the probe and control fields are in different spatial modes,the system is superior for implementing cavity QED-based photonic quantum networks.

  10. Quantum frequency up-conversion with a cavity

    Institute of Scientific and Technical Information of China (English)

    Bai Yun-Fei; Zhai Shu-Qin; Gao Jiang-Rui; Zhang Jun-Xiang

    2011-01-01

    The quantum state transfer from subharmonic frequency to harmonic frequency based on asymmetrically pumped second harmonic generation in a cavity is investigated theoretically. The performance of noise-free frequency up-conversion is evaluated by the signal transfer coefficient and the conversion efficiency,in which both the quadrature fluctuation and the average photon number are taken into consideration.It is shown that the quantum property can be preserved during frequency up-conversion via operating the cavity far below the threshold.The dependences of the transfer coefficient and the conversion efficiency on pump parameter,analysing frequency,and cavity extra loss are also discussed.

  11. Entangling movable mirrors in a double cavity system

    DEFF Research Database (Denmark)

    Pinard, Michel; Dantan, Aurelien Romain; Vitali, David;

    2005-01-01

    We propose a double-cavity set-up capable of generating a stationary entangled state of two movable mirrors at cryogenic temperatures. The scheme is based on the optimal transfer of squeezing of input optical fields to mechanical vibrational modes of the mirrors, realized by the radiation pressur...

  12. Accoustic Localization of Breakdown in Radio Frequency Accelerating Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Lane, Peter Gwin [IIT, Chicago

    2016-07-01

    Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W is achie...

  14. Cavity design for high-frequency axion dark matter detectors

    CERN Document Server

    Stern, I; Hoskins, J; Sikivie, P; Sullivan, N S; Tanner, D B; Carosi, G; van Bibber, K

    2016-01-01

    In an effort to extend the usefulness of microwave cavity detectors to higher axion masses, above ~8 $\\mu$eV (~2 GHz), a numerical trade study of cavities was conducted to investigate the merit of using variable periodic post arrays and regulating vane designs for higher-frequency searches. The results show that both designs could be used to develop resonant cavities for high-mass axion searches. Multiple configurations of both methods obtained the scanning sensitivity equivalent to approximately 4 coherently coupled cavities with a single tuning rod.

  15. Cavity Mode Frequencies and Large Optomechanical Coupling in Two-Membrane Cavity Optomechanics

    CERN Document Server

    Li, J; Malossi, N; Vitali, D

    2015-01-01

    We study the cavity mode frequencies of a Fabry-Perot cavity containing two vibrating dielectric membranes and the corresponding optomechanical coupling. Due to optical interference, extremely large optomechanical coupling of the membrane relative motion is achieved when the two membranes are placed very close to a resonance of the inner cavity formed by the two membranes, and in the limit of highly reflective membranes. The upper bound of the coupling strength is given by the optomechanical coupling associated with the much shorter inner cavity, consistently with the analysis of A. Xuereb et al., Phys. Rev. Lett. 109, 223601 (2012).

  16. Dielectric supported radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, David U. L. (Rancho Palos Verdes, CA); Lee, Terry G. (Cupertino, CA)

    2000-01-01

    A device which improves the electrical and thermomechanical performance of an RF cavity, for example, in a disk-loaded accelerating structure. A washer made of polycrystalline diamond is brazed in the middle to a copper disk washer and at the outer edge to the plane wave transformer tank wall, thus dissipating heat from the copper disk to the outer tank wall while at the same time providing strong mechanical support to the metal disk. The washer structure eliminates the longitudinal connecting rods and cooling channels used in the currently available cavities, and as a result minimizes problems such as shunt impedance degradation and field distortion in the plane wave transformer, and mechanical deflection and uneven cooling of the disk assembly.

  17. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    Science.gov (United States)

    Ho, Jen-Hsuan; Berkhoff, Arthur

    2014-03-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of two panels with air in between and offers the advantages of low sound transmission at high frequencies, low heat transmission, and low weight. The double panel structure is widely used, such as in the aerospace and automotive industries. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel's noise control performance. Applying active structural acoustic control to the panels or active noise control to the cavity has been discussed in many papers. In this paper, the resonances of the panels and the cavity are considered simultaneously to further reduce the transmitted noise through an existing double panel structure. A structural-acoustic coupled model is developed to investigate and compare various structural control and cavity control methods. Numerical analysis and real-time control results show that structural control should be applied to both panels. Three types of cavity control sources are presented and compared. The results indicate that the largest noise reduction is obtained with cavity control by loudspeakers modified to operate as incident pressure sources.

  18. Mechanical properties of niobium radio-frequency cavities

    International Nuclear Information System (INIS)

    Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 620 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structures have been conducted up to the tensile strength of the material. Finite-element analysis of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young’s modulus value of 88.5 GPa and a Poisson’s ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities made from ingot material with large crystals are comparable to those of cavities made of fine-grain niobium

  19. Mechanical properties of niobium radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G., E-mail: gciovati@jlab.org [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Dhakal, P.; Matalevich, J.; Myneni, G. [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Schmidt, A.; Iversen, J.; Matheisen, A.; Singer, W. [Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607 Hamburg (Germany)

    2015-08-26

    Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 620 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structures have been conducted up to the tensile strength of the material. Finite-element analysis of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young’s modulus value of 88.5 GPa and a Poisson’s ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities made from ingot material with large crystals are comparable to those of cavities made of fine-grain niobium.

  20. Tunable Single-Frequency Intracavity Frequency-Doubled Ti:Sapphire Laser around 461 nm

    Institute of Scientific and Technical Information of China (English)

    李凤琴; 石柱; 李永民; 彭堃墀

    2011-01-01

    We demonstrate a tunable continuous-wave single frequency intracavity frequency-doubled Ti:sapphire laser.The highest output power of 280mW at 461.62nm is obtained by employing a type-I phase-matched BIBO crystal and the peak-to-peak fluctuation of the power is less than ±1% within three hours.The frequency stability is better than ±2.22 MHz over 10min when the laser is locked to a confocal Fabry-Perot cavity.A three-plate birefringent filter allows for the tunable range from 457nm to 467nm,which covers the absorption line of the strontium atoms(460.86nm).%We demonstrate a tunable continuous-wave single frequency intracavity frequency-doubled Ti:sapphire laser. The highest output power of 280mW at 461.62nm is obtained by employing a type-I phase-matched BIBO crystal and the peak-to-peak fluctuation of the power is less than ±1% within three hours. The frequency stability is better than ±2.22MHz over lOmin when the laser is locked to a confocal Fabry-Perot cavity. A three-plate birefringent filter allows for the tunable range from 457nm to 467 nm, which covers the absorption line of the strontium atoms (460.86 nm).

  1. Cavity-enhanced optical frequency combspectroscopy

    DEFF Research Database (Denmark)

    Balslev-Clausen, David Morten; Thorpe, M. J.; Kirchner, M. S.;

    2008-01-01

    Broad-bandwidth, high-spectral-resolution optical detection of human breath has identified multiple important biomarkers correlated with specific diseases and metabolic processes. This optical-frequency-comb-based breath analysis system comes with excellent performance in all criteria: high...

  2. 双端抽运腔内和频紫外激光器的实验研究%Experiment of double-end-pumped intra-cavity triple frequency ultraviolet laser

    Institute of Scientific and Technical Information of China (English)

    郑伯然; 姚育成; 黄楚云

    2013-01-01

    为了获得高功率全固态355nm紫外激光器,采用平平腔结构,通过LD双端抽运Nd∶YVO4晶体,在声光Q开关调制作用下产生1064nm脉冲基频光,利用两块LBO晶体分别进行腔内倍频、和频产生355nm紫外激光.在LD抽运功率54W、调制频率40kHz的条件下,获得紫外的最高输出功率为6.67W,脉冲宽度为20ns,M2 =1.1.结果表明,腔内和频可得到高效率、高光束质量的紫外激光输出.%In order to get a high power and solid-state UV laser, based on a plane-plane cavity, with laser diode double-end pumping Nd:YV04 crystal, fundamental pulse at 1064nm was output under modulation of a acousto-optic Q-switch. Then the laser at 355nm was generated by the second harmonic generation and the third harmonic generation with two LBO crystals. Under the pump power of 54W, 6. 67W, average output power at 355nm was obtained at 40kHz with the pulse width of 20ns and M2 =1.1. The results show that the design of intra-cavity third harmonic generation lasers can give high conversion efficiency and good beam quality.

  3. Stabilization of an optical frequency comb to an external cavity

    OpenAIRE

    Rydberg, Olof

    2014-01-01

    The subject of this master's thesis is stabilizing a frequency comb laser to an external cavity using a couple of servo controllers. The aim of the project was to build a pair of servo controllers, replacing parts of the existing commercial and proprietary solution already in use. The system under control is an optical frequency comb, which is locked to an external cavity and is used for trace gas detection and spectroscopy. The comb is a broadband light source and needs to be locked to the e...

  4. Low frequency fluctuation with two external cavity reflectors

    Institute of Scientific and Technical Information of China (English)

    王春林; 伍剑; 林金桐

    2003-01-01

    The dynamics of a semiconductor laser with two optical feedbacks is studied in this paper. A new set of nonlinear rate equations that can describe external cavity semiconductor lasers with any amount of two optical feedbacks is proposed. It is found that when the laser is biased above the threshold and subjected to one feedback, the other feedback can induce low-frequency fluctuations.

  5. 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.

  6. Self-Frequency Shift of Cavity Soliton in Kerr Frequency Comb

    CERN Document Server

    Zhang, Lin; Kimerling, Lionel C; Michel, Jurgen

    2014-01-01

    We show that the ultrashort cavity soliton in octave-spanning Kerr frequency comb generation exhibits striking self-adaptiveness and robustness to external perturbations, resulting in a novel frequency shifting/cancellation mechanism and gigantic dispersive wave generation in response to the strong frequency dependence of Kerr nonlinearity, Raman scattering, chromatic dispersion, and cavity Q. These observations open up a great avenue towards versatile manipulation of nonlinear soliton dynamics, flexible spectrum engineering of mode-locked Kerr frequency combs, and highly efficient frequency translation of optical waves.

  7. Oscillatory Double-Diffusive Convection in a Horizontal Cavity with Soret and Dufour Effects

    CERN Document Server

    Wang, Jin; Zhang, Yuwen

    2016-01-01

    Oscillatory double-diffusive convection in horizontal cavity with Soret and Dufour effects is investigated numerically based on SIMPLE algorithm with QUICK scheme in non-uniform staggered grid system. The results show that double-diffusive convection develops from steady-state convection-dominated, periodic oscillatory, quasi-periodic oscillatory to chaotic flow, and finally return to periodic oscillation as buoyancy ratio increases. Moreover, fundamental frequency and fluctuation amplitude increase with buoyancy ratio. As Rayleigh number increases, transition trendy of oscillatory convection is similar to that of buoyancy ratio. But the return of periodic oscillation from chaos is not obtained as Rayleigh number increases. As aspect ratio decreases, the oscillatory convection evolves from periodic into steady-state. In addition, fundamental frequency increases at first and then decreases while fluctuation amplitude decreases with aspect ratio.

  8. Frequency-Agile Differential Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Reed, Zachary; Hodges, Joseph

    2015-06-01

    The ultimate precision of highly sensitive cavity-enhanced spectroscopic measurements is often limited by interferences (etalons) caused by weak coupled-cavity effects. Differential measurements of ring-down decay constants have previously been demonstrated to largely cancel these effects, but the measurement acquisition rates were relatively low [1,2]. We have previously demonstrated the use of frequency agile rapid scanning cavity ring-down spectroscopy (FARS-CRDS) for acquisition of absorption spectra [3]. Here, the method of rapidly scanned, frequency-agile differential cavity ring-down spectroscopy (FADS-CRDS) is presented for reducing the effect of these interferences and other shot-to-shot statistical variations in measured decay times. To this end, an electro-optic phase modulator (EOM) with a bandwidth of 20 GHz is driven by a microwave source, generating pairs of sidebands on the probe laser. The optical resonator acts as a highly selective optical filter to all laser frequencies except for one tunable sideband. This sideband may be stepped arbitrarily from mode-to-mode of the ring-down cavity, at a rate limited only by the cavity buildup/decay time. The ability to probe any cavity mode across the EOM bandwidth enables a variety of methods for generating differential spectra. The differential mode spacing may be changed, and the effect of this method on suppressing the various coupled-cavity interactions present in the system is discussed. Alternatively, each mode may also be differentially referenced to a single point, providing immunity to temporal variations in the base losses of the cavity while allowing for conventional spectral fitting approaches. Differential measurements of absorption are acquired at 3.3 kHz and a minimum detectable absorption coefficient of 5 x10-12 cm-1 in 1 s averaging time is achieved. 1. J. Courtois, K. Bielska, and J.T Hodges J. Opt. Soc. Am. B, 30, 1486-1495, 2013 2. H.F. Huang and K.K. Lehmann App. Optics 49, 1378

  9. Updating the CSNS injector linac to 250 MeV with superconducting double-spoke cavities

    CERN Document Server

    Zhi-Hui, LI

    2014-01-01

    In order to update the beam power from 100 kW to 250 kW in China spallation neutron source (CSNS) Phase II, one of the important measures is to replace the 80 meters long beam transport line between the present 80 MeV linac injector and the RCS to another kind of acceleration structure. In this paper, we proposed a scheme based on 324 MHz double-spoke superconducting cavities. Unlike the superconducting elliptical cavity and normal conducting CCL structure, the double-spoke cavity belongs to TE mode structure and has smaller transvers dimension compared with that of TH mode one. It can work at base frequency as the DTL section, so that the cost and complexity of the RF system will be much decreased, and the behaviors of the beam dynamics are also improved significantly because of the low charge density and larger longitudinal acceptance. Furthermore, because of the relatively longer interactive length between charged particle and the electromagnetic field per cell, it needs relatively less cell numbers and it...

  10. Frequency Control through Pulse Width Modulation for NRF Cavities

    OpenAIRE

    Pfeiffer, Sven

    2015-01-01

    This contribution presents the latest development for high precision regulation of normalconducting radio frequency (NRF) cavities operatedin a pulsed mode. The system identification, essential to achieve high performance control, is based on a grey box model, with a priori knowledge about the physical behavior. The feedback regulation concept is separated into two basic controller parts. An RF controller design, based on the identified RF field model, is followed by a system identification a...

  11. Theoretical Analysis About Quantum Noise Squeezing of Optical Fields From an Intracavity Frequency-Doubled Laser

    Science.gov (United States)

    Zhang, Kuanshou; Xie, Changde; Peng, Kunchi

    1996-01-01

    The dependence of the quantum fluctuation of the output fundamental and second-harmonic waves upon cavity configuration has been numerically calculated for the intracavity frequency-doubled laser. The results might provide a direct reference for the design of squeezing system through the second-harmonic-generation.

  12. High-power dual-wavelength external-Cavity diode laser based on tapered amplifier with tunable terahertz frequency difference

    DEFF Research Database (Denmark)

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

    2011-01-01

    Tunable dual-wavelength operation of a diode laser system based on a tapered diode amplifier with double-Littrow external-cavity feedback is demonstrated around 800nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5:0 THz...

  13. Intracavity frequency-doubled degenerate laser

    CERN Document Server

    Liew, Seng Fatt; Weiler, Sascha; Monjardin-Lopez, Jesus Fernando; Ramme, Mark; Redding, Brandon; Choma, Michael A; Cao, Hui

    2016-01-01

    We develop a green light source with low spatial coherence via intracavity frequency doubling of a solid-state degenerate laser. The second harmonic emission supports many more transverse modes than the fundamental emission, and exhibit lower spatial coherence. A strong suppression of speckle formation is demonstrated for both fundamental and second harmonic beams. Using the green emission for fluorescence excitation, we show the coherent artifacts are removed from the full-field fluorescence images. The high power, low spatial coherence and good directionality makes the green degenerate laser an attractive illumination source for parallel imaging and projection display.

  14. Gravitational Wave Detection with High Frequency Phonon Trapping Acoustic Cavities

    CERN Document Server

    Goryachev, Maxim

    2014-01-01

    There are a number of theoretical predictions for astrophysical and cosmological objects, which emit high frequency ($10^6-10^9$~Hz) Gravitation Waves (GW) or contribute somehow to the stochastic high frequency GW background. Here we propose a new sensitive detector in this frequency band, which is based on existing cryogenic ultra-high quality factor quartz Bulk Acoustic Wave cavity technology, coupled to near-quantum-limited SQUID amplifiers at $20$~mK. We show that spectral strain sensitivities reaching $10^{-22}$ per $\\sqrt{\\text{Hz}}$ per mode is possible, which in principle can cover the frequency range with multiple ($>100$) modes with quality factors varying between $10^6-10^{10}$ allowing wide bandwidth detection. Due to its compactness and well established manufacturing process, the system is easily scalable into arrays and distributed networks that can also impact the overall sensitivity and introduce coincidence analysis to ensure no false detections.

  15. Internally-frequency-doubled Yb fiber laser with 15 W CW green output

    OpenAIRE

    Cieslak, Rafal; Clarkson, William Andrew

    2011-01-01

    In this paper we present a high power continuous-wave (CW) green source using a novel approach for frequency doubling of high power CW fiber lasers based on an internal resonant enhancement cavity integrated within the fiber laser resonator. The experimental configuration (shown in Fig. 1) comprised a double-clad fiber with an Yb-doped core in a simple standing-wave resonator. Feedback for lasing was provided by a diffraction grating at one end of the fiber, and by an external cavity containi...

  16. 半导体激光端泵腔内倍频Nd:YVO4/LBO连续波8W绿光激光器%Diode-laser End-pumped Intra-cavity Frequency Doubling Nd:YVO4/LBO Continuous-wave 8W Green Laser

    Institute of Scientific and Technical Information of China (English)

    田丰; 解慧明; 陈浩伟; 赵致民; 李隆; 白晋涛

    2004-01-01

    利用两个半导体激光二极管,双端泵浦Nd∶ YVO4晶体,LBO采用I类非临界相位匹配、腔内倍频.在28.9 W的泵浦功率下,获得了8 W连续波0.532 μm绿光输出,其光-光转换效率为27.7%.%A simple way to achieve 8W CW output green laser with intra-cavity frequency doubling in a Nd∶ YVO4 laser doubly longitudinally pumped by two diode lasers is reported. With I-type non-critical-phase-match(NCPM) and temperature tuning of LBO crystal, a maximum of 8 W continuous-wave output at 0.532 μm has been obtained. With 28.9 W pump power, the optical-optical conversion efficiency is 27.7%.

  17. Single-frequency and tunable operation of a continuous intracavity-frequency-doubled singly resonant optical parametric oscillator.

    Science.gov (United States)

    My, Thu-Hien; Drag, Cyril; Bretenaker, Fabien

    2008-07-01

    A widely tunable continuous intracavity-frequency-doubled singly resonant optical parametric oscillator based on MgO-doped periodically poled stoichiometric lithium tantalate crystal is described. The idler radiation resonating in the cavity is frequency doubled by an intracavity BBO crystal. Pumped in the green, this system can provide up to 485 mW of single-frequency orange radiation. The system is continuously temperature tunable between 1170 and 1355 nm for the idler, 876 and 975 nm for the signal, and between 585 and 678 nm for the doubled idler. The free-running power and frequency stability of the system have been observed to be better than those for a single-mode dye laser.

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

    CERN Document Server

    Stappel, M; Kolbe, D; Walz, J

    2012-01-01

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

  19. Single-frequency and tunable operation of a continuous intracavity-frequency-doubled singly resonant optical parametric oscillator.

    Science.gov (United States)

    My, Thu-Hien; Drag, Cyril; Bretenaker, Fabien

    2008-07-01

    A widely tunable continuous intracavity-frequency-doubled singly resonant optical parametric oscillator based on MgO-doped periodically poled stoichiometric lithium tantalate crystal is described. The idler radiation resonating in the cavity is frequency doubled by an intracavity BBO crystal. Pumped in the green, this system can provide up to 485 mW of single-frequency orange radiation. The system is continuously temperature tunable between 1170 and 1355 nm for the idler, 876 and 975 nm for the signal, and between 585 and 678 nm for the doubled idler. The free-running power and frequency stability of the system have been observed to be better than those for a single-mode dye laser. PMID:18594663

  20. 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%.

  1. Generation of continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling of a Ti:sapphire laser.

    Science.gov (United States)

    Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

    2010-03-20

    We have generated continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling a high-power Ti:sapphire laser in an external enhancement cavity. An LBO crystal that is Brewster-cut and antireflection coated on both ends is used for a long-term stable frequency doubling. By optimizing the input coupler's reflectivity, we could generate 1.5 W 378 nm radiation from a 5 W 756 nm Ti:sapphire laser. According to our knowledge, this is the highest CW frequency-doubled power of a Ti:sapphire laser. PMID:20300165

  2. Resonant-frequency discharge in a multi-cell radio frequency cavity

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, S; Upadhyay, J; Mammosser, J; Nikolic, M; Vuskovic, L

    2014-11-07

    We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

  3. Prototype superconducting radio-frequency cavity for LEP

    CERN Multimedia

    1985-01-01

    This niobium superconducting cavity was part of the prototype stages for an upgrade to LEP, known as LEP-2. Superconducting cavities would eventually replace the traditional copper cavities and allow beam energies of 100 GeV.

  4. Cavity ringdown spectroscopy with widely tunable swept-frequency lasers

    International Nuclear Information System (INIS)

    Full text: A novel approach to cavity ringdown (CRD) spectroscopy based on swept-frequency (SF) lasers enables rapid measurement of CRD absorption spectra. Our new SF CRD spectrometer incorporates a miniature widely-tunable continuous-wave SF laser and requires less than 1 s to record wide-ranging absorption spectra with high sensitivity in a single rapid sweep of the laser frequency. The spectrometer has a single-ended transmitter-receiver configuration based on retro-reflected optical-heterodyne detection, and yields a simple, compact, versatile instrument for efficient sensing of gases. The performance of the spectrometer is demonstrated by measuring weak absorption spectra of carbon dioxide gas at 1.5-1.6 μm. Copyright (2005) Australian Institute of Physics

  5. High-efficiency frequency doubling of continuous-wave laser light

    CERN Document Server

    Ast, Stefan; Schönbeck, Axel; Lastzka, Nico; Steinlechner, Jessica; Eberle, Tobias; Mehmet, Moritz; Steinlechner, Sebastian; Schnabel, Roman

    2011-01-01

    We report on the observation of high efficiency frequency doubling of 1550 nm continuous-wave laser light in a nonlinear cavity containing a periodically poled potassium titanyl phosphate crystal (PPKTP). The fundamental field had a power of 1.10 W and was converted into 1.05 W at 775 nm, yielding a total external conversion efficiency of (95 \\pm 1)%. The latter value is based on the measured depletion of the fundamental field being consistent with the absolute values derived from numerical simulations. According to our model, the conversion efficiency achieved was limited by the non-perfect mode-matching into the nonlinear cavity and the pump power available. Our result shows that cavity-assisted frequency conversion based on PPKTP is well suited for low-decoherence frequency conversion of quantum states of light.

  6. Frequency tuning and stability of Nd:YVO4 in a dual coupled cavity

    DEFF Research Database (Denmark)

    Hansen, P. L.; Pedersen, Christian; Buchhave, Preben;

    1996-01-01

    Frequency tuning and stability properties of single- and multi-cavity designs have been investigated theoretically and experimentally. Special attention is paid to a dual coupled cavity single-frequency diode-pumped solid-state Nd:YVO4 laser crystal. 350 mW single frequency output power has...... previously been demonstrated using dual coupled linear cavity. Frequency tuning versus temperature and cavity length of a coupled cavity Nd:YVO4 have been investigated and compared to those of a non-planar monolithic, unidirectional Nd:YAG ring laser. A way to extend the tuning range by design of the air to...

  7. Birefringence-induced frequency beating in high-finesse cavities by continuous-wave cavity ring-down spectroscopy

    Science.gov (United States)

    Dupré, Patrick

    2015-11-01

    By analyzing the decaying intensity, leaking out a high-finesse cavity previously "filled" by a cw laser source (using the cavity ring-down spectroscopy technique), we observed frequency beating between what we think are two orthogonal eigenpolarization states of the intracavity electromagnetic field. The time decay (ring down) is analyzed by varying the angle of the polarization analyzer located in front of the detector. A full modeling of the observed signal is proposed. It is based on the Jones matrix formalism required for modeling the cavity behavior following a rotated phase shifter. The full transfer function is first established in the frequency domain, and then Fourier transformed to recover the temporal response. The same optical cavity, i.e., constituted of the same set of mirrors, is used at two different wavelengths (˜800 and ˜880 nm). It demonstrates the differences in behavior between a high-finesse cavity (˜400 000 ) and a lower finesse cavity (˜50 000 ). Beating frequency, characteristics time, and beat amplitude are mainly discussed versus the analyzer angle. A cavity birefringence of ˜1.6 ×10-5 rad, resulting from the mirror birefringence is suggested. If the current analysis is in agreement with pulsed CRDS experiments (polarimetry) obtained in an isotropic moderate-finesse cavity, it differs from a recent work report on a high-finesse cavity associated with a source mode locking [Phys. Rev. A 85, 013837 (2012), 10.1103/PhysRevA.85.013837].

  8. Enhanced vacuum Rabi splitting and double dark states in a composite atom-cavity system

    Institute of Scientific and Technical Information of China (English)

    Tao LI; Hai-tao ZHOU; Zhong-hua LI; Yun-fei BAI; Yuan LI; Jiang-rui GAO; Jun-xiang ZHANG

    2009-01-01

    The transmission spectrum of four-level atoms in a cavity is calculated. It is shown that the four separate peaks associated with normal mode splitting and intra-cavity double dark states can be observed simultaneously. The position and intensity of the four peaks can be controlled by the intensity of the third interacting light. Therefore, the enhancement of normal mode splitting by a third coupling light of the intra-cavity four-level atoms is developed.

  9. Design and prototyping of HL-LHC double quarter wave crab cavities for SPS test

    Energy Technology Data Exchange (ETDEWEB)

    Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Artoos, K. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capelli, T. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Carra, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Leuxe, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Kuder, N. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Zanoni, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratti, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-05-03

    The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. Two DQW crab cavities are under fabrication and will be tested with beam in the Super Proton Synchrotron (SPS) at CERN by 2017. This paper describes the design and prototyping of the DQW crab cavities for the SPS test.

  10. Design and Prototyping of HL-LHC Double Quarter Wave Crab Cavities for SPS Test

    CERN Document Server

    Verdú-Andrés, S; Wu, Q; Xiao, B P; Belomestnykh, S; Ben-Zv, I; Alberty, L; Artoos, Kurt; Calaga, Rama; Capatina, Ofelia; Capelli, Teddy; Carra, Federico; Leuxe, Raphael; Kuder, Norbert; Zanoni, Carlo; Li, Z; Ratti, A

    2015-01-01

    The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. Two DQW crab cavities are under fabrication and will be tested with beam in the Super Proton Synchrotron (SPS) at CERN by 2017. This paper describes the design and prototyping of the DQW crab cavities for the SPS test.

  11. Active and passive stabilization of a high-power UV frequency-doubled diode laser

    CERN Document Server

    Eismann, Ulrich; Simeonidis, Konstantinos; Keller, Felix; Rohde, Felix; Opalevs, Dmitrijs; Scholz, Matthias; Kaenders, Wilhelm; Stuhler, Jürgen

    2016-01-01

    We present a resonantly frequency-doubled tapered amplified semiconductor laser system emitting up to 2.6 W blue light at 400 nm. The output power is stable on both short and long timescales with 0.12% RMS relative intensity noise, and less than 0.15%/h relative power loss over 16 hours of free running continuous operation. Furthermore, the output power can be actively stabilized, and the alignment of the input beams of the tapered amplifier chip, the frequency doubling cavity and-in case of fiber output-the fiber can be optimized automatically using computer-controlled mirrors.

  12. Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B; Belomestnykh, S; Ben-Zvi, I; Calaga, Rama; Cullen, C; Capatina, Ofelia; Hammons, L; Li, Z; Marques, C; Skaritka, J; Verdú-Andres, S; Wu, Q

    2015-01-01

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109 . We report the test results of this design.

  13. Direct modulation of an ultra-long doped fiber external cavity semiconductor laser at multiples of the cavity resonant frequency

    Science.gov (United States)

    Liu, Runnan; Wu, Ke; Kashyap, Raman

    2007-06-01

    The doped fiber external cavity semiconductor laser (DFECL) has been reported with a simple structure, high power, narrow linewidth, and stable wavelength. The DFECL is mostly suitable to be an optical carrier generator for external modulation or microwave optical generation. Because of mode locking, the DFECL, with saturable absorber in its external cavity, has the possibility to be direct modulated at its multiples of cavity resonant frequency. The useful modulation frequency of the laser can be increased significantly. In this paper, we present experimental results about the transmission response of direct modulation of an ultra-long DFECL, and the modulated microwave signal transmission at the frequency of the 22 nd. multiple of the cavity resonant frequency. Modulated narrow bandwidth microwave signals at 2.4GHz were transmitted by this DFECL. The received RF spectrum has no obvious distortion for a 10MHz narrow band microwave signal and, all the resonant and harmonic frequencies in the 0~2.5GHz region are 50 dB lower than the transmitted wave. The results show that narrowband modulated microwave can be transmitted at high frequency by the long DFECL; even through the cavity round-trip frequency is very low. We conclude that this ultra-long doped fiber external cavity semiconductor laser can be used for narrowband wireless communication with direct modulation.

  14. Three-Dimensional Electromagnetic High Frequency Axisymmetric Cavity Scars.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt

    2014-10-01

    This report examines the localization of high frequency electromagnetic fi elds in three-dimensional axisymmetric cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This report treats both the case where the opposing sides, or mirrors, are convex, where there are no interior foci, and the case where they are concave, leading to interior foci. The scalar problem is treated fi rst but the approximations required to treat the vector fi eld components are also examined. Particular att ention is focused on the normalization through the electromagnetic energy theorem. Both projections of the fi eld along the scarred orbit as well as point statistics are examined. Statistical comparisons are m ade with a numerical calculation of the scars run with an axisymmetric simulation. This axisymmetric cas eformstheoppositeextreme(wherethetwomirror radii at each end of the ray orbit are equal) from the two -dimensional solution examined previously (where one mirror radius is vastly di ff erent from the other). The enhancement of the fi eldontheorbitaxiscanbe larger here than in the two-dimensional case. Intentionally Left Blank

  15. Signal line shapes of Fourier transform cavity-enhanced frequency modulation spectroscopy with optical frequency combs

    CERN Document Server

    Johansson, Alexandra C; Khodabakhsh, Amir; Foltynowicz, Aleksandra

    2016-01-01

    We present a thorough analysis of the signal line shapes of Fourier transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS). We discuss the signal dependence on the ratio of the modulation frequency, f${_m}$, to the molecular line width, {\\Gamma}. We compare a full model of the signals and a simplified absorption-like analytical model that has high accuracy for low f${_m}$/{\\Gamma} ratios and is much faster to compute. We verify the theory experimentally by measuring and fitting NICE-OFCS spectra of CO${_2}$ at 1575 nm using a system based on an Er:fiber femtosecond laser and a cavity with a finesse of ~11000.

  16. Frequency stability measurement of a transfer-cavity-stabilized diode laser by using an optical frequency comb

    Science.gov (United States)

    Uetake, S.; Matsubara, K.; Ito, H.; Hayasaka, K.; Hosokawa, M.

    2009-10-01

    We report results of frequency stability measurements of an extended cavity diode laser (ECDL) whose frequency is stabilized by a non-evacuated scanning transfer cavity. The transfer cavity is locked to a commercial frequency stabilized helium-neon laser. Frequency stability is measured by use of an optical frequency comb. The environmental perturbations (variations of temperature, air pressure, and humidity) are also simultaneously measured. The observed frequency drift of the ECDL is well explained by environmental perturbations. An atmospheric pressure variation, which is difficult to control with a non-evacuated cavity, is mainly affected to the frequency stability. Thus we put the cavity into a simple O-ring sealed (non-evacuated) tube. With this simple O-ring sealed tube, the frequency drift is reduced by a factor of 3, and the Allan variance reaches a value of 2.4×10-10, corresponds to the frequency stability of 83 kHz, at the average time of 3000 s. Since the actual frequency drift is well estimated by simultaneous measurement of the ambient temperature, pressure, and humidity, a feed-forward compensation of frequency drifts is also feasible in order to achieve a higher frequency stability with a simple non-evacuated transfer cavity.

  17. Multiphysics Analysis of Frequency Detuning in Superconducting RF Cavities for Proton Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Awida, M. H. [Fermilab; Gonin, I. [Fermilab; Passarelli, D. [Fermilab; Sukanov, A. [Fermilab; Khabiboulline, T. [Fermilab; Yakovlev, V. [Fermilab

    2016-01-22

    Multiphysics analyses for superconducting cavities are essential in the course of cavity design to meet stringent requirements on cavity frequency detuning. Superconducting RF cavities are the core accelerating elements in modern particle accelerators whether it is proton or electron machine, as they offer extremely high quality factors thus reducing the RF losses per cavity. However, the superior quality factor comes with the challenge of controlling the resonance frequency of the cavity within few tens of hertz bandwidth. In this paper, we investigate how the multiphysics analysis plays a major role in proactively minimizing sources of frequency detuning, specifically; microphonics and Lorentz Force Detuning (LFD) in the stage of RF design of the cavity and mechanical design of the niobium shell and the helium vessel.

  18. Conical Double Frequency Emission by Femtosecond Laser Pulses from DKDP

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xi-Peng; JIANG Hong-Bing; TANG Shan-Chun; GONG Qi-Huang

    2009-01-01

    Conical double frequency emission is investigated by femtosecond laser pulses at a wavelength of 800nm in a DKDP crystal. It is demonstrated that the sum frequency of incident wave and its scattering wave accounts for the conical double frequency emission. The gaps on the conical rings are observed and they are very sensitive to the propagation direction, and thus could be used to detect the small angle deviation of surface direction.

  19. Tunable All-Solid-State Continuous Wave Intra-Cavity Frequency-Doubled Nd∶YVO4/LBO 671 nm Ring Laser%可调谐全固态Nd∶YVO4/LBO倍频连续671nm环形激光器

    Institute of Scientific and Technical Information of China (English)

    孙桂侠; 刘涛; 钱金宁; 苏新军; 张晓卫; 张志忠

    2013-01-01

    A tunable all-solid-state Nd∶ YVO4 ring laser,intra-cavity frequency doubled by a type-Ⅰ matched LBO crystal with 671 nm laser output,is demonstrated in this paper.The laser resonator is designed with a four-mirror ring configuration.The YVO4-Nd∶YVO4 composite crystal is end-pumped by a 880 nm laser diode (LD).A Faraday optical diode consisted with TGG rotator and half-wave plate is placed inside the resonator for forcing the laser to operate unidirectionally.A solid Fabry-Perot etalon and a piezoelectric-ceramic are inserted into the cavity for tuning the wavelength.The single-frequency output power of 1.08 W at 671 nm is obtained under the pumping power of 23 W (the absorbed pumping power of 14.5 W),the optical-optical conversion efficiency is about 7.4%.With the etalon tuning,a maximal output power of 738 mW is obtained.%描述了一种可调谐全固态Nd∶ YVO4/LBO倍频连续671 nm环形激光器的结构参数和相关实验研究.激光器采用四镜环形腔结构,利用880 nm激光二极管(LD)端面抽运YVO4-Nd∶ YVO4复合晶体和Ⅰ类相位匹配的LBO倍频方式,加入TGG旋光器和λ/2波片组成的光学单向器实现单向运转,通过对法布里-珀罗(F-P)标准具角度和腔镜压电晶体电压的调节实现了激光输出波长671 nm附近的调频.在抽运功率为23 W,吸收抽运功率为14.5W时,输出单频671 nm连续红光最高功率为1.08W,光-光转换效率为7.4%;加标准具调谐时,获得了最高功率为738 mW的可调谐红光输出.

  20. Realization of a double-barrier resonant tunneling diode for cavity polaritons.

    Science.gov (United States)

    Nguyen, H S; Vishnevsky, D; Sturm, C; Tanese, D; Solnyshkov, D; Galopin, E; Lemaître, A; Sagnes, I; Amo, A; Malpuech, G; Bloch, J

    2013-06-01

    We report on the realization of a double-barrier resonant tunneling diode for cavity polaritons, by lateral patterning of a one-dimensional cavity. Sharp transmission resonances are demonstrated when sending a polariton flow onto the device. We show that a nonresonant beam can be used as an optical gate and can control the device transmission. Finally, we evidence distortion of the transmission profile when going to the high-density regime, signature of polariton-polariton interactions. PMID:25167519

  1. Realization of a Double-Barrier Resonant Tunneling Diode for Cavity Polaritons

    OpenAIRE

    Nguyen, Hai Son; Vishnevsky, Dmitry; Sturm, Chris; Tanese, Dimitrii; Solnyshkov, Dmitry; Galopin, Elisabeth; Lemaître, Aristide; Sagnes, Isabelle; Amo, Alberto; Malpuech, Guillaume; Bloch, Jacqueline

    2013-01-01

    We report on the realization of a double barrier resonant tunneling diode for cavity polaritons, by lateral patterning of a one-dimensional cavity. Sharp transmission resonances are demonstrated when sending a polariton flow onto the device. We use a non-resonant beam can be used as an optical gate and control the device transmission. Finally we evidence distortion of the transmission profile when going to the high density regime, signature of polariton-polariton interactions.

  2. Realization of a Double-Barrier Resonant Tunneling Diode for Cavity Polaritons

    Science.gov (United States)

    Nguyen, H. S.; Vishnevsky, D.; Sturm, C.; Tanese, D.; Solnyshkov, D.; Galopin, E.; Lemaître, A.; Sagnes, I.; Amo, A.; Malpuech, G.; Bloch, J.

    2013-06-01

    We report on the realization of a double-barrier resonant tunneling diode for cavity polaritons, by lateral patterning of a one-dimensional cavity. Sharp transmission resonances are demonstrated when sending a polariton flow onto the device. We show that a nonresonant beam can be used as an optical gate and can control the device transmission. Finally, we evidence distortion of the transmission profile when going to the high-density regime, signature of polariton-polariton interactions.

  3. Cryogenic test of double quarter wave crab cavity for the LHC High luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cullen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Marques, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.

  4. Cavity-photon-switched coherent transient transport in a double quantum waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Nzar Rauf, E-mail: nra1@hi.is; Gudmundsson, Vidar, E-mail: vidar@raunvis.hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tang, Chi-Shung [Department of Mechanical Engineering, National United University, 1, Lienda, 36003 Miaoli, Taiwan (China); Manolescu, Andrei [School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik (Iceland)

    2014-12-21

    We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavity-photon tunable semiconductor quantum waveguide implementation of an inverter quantum gate, in which the output of the waveguide system may be selected via the selection of an appropriate photon number or “photon frequency” of the cavity. In addition, the importance of the photon polarization in the cavity, that is, either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

  5. Superconducting radio frequency cavities: design, development and results

    International Nuclear Information System (INIS)

    In recent years, the development of superconducting niobium cavities has evoked a lot of interest among the accelerator physics community of India. Many laboratories are planning to develop superconducting niobium cavities for new accelerators and applications. Inter-University Accelerator Centre (IUAC) has been engaged in the indigenous development of niobium resonators for over a decade. During this period, several quarter wave resonators have been successfully built, tested and installed in the superconducting linac at IUAC. A new niobium low beta resonator for the High Current Injector (HCI) project has been designed, prototyped and tested. In addition to the in-house projects, IUAC is nearing completion of two niobium single spoke resonators (SSR1) for Fermi Lab, USA. Under the Indian Institutions and Fermi Lab Collaboration (IIFC), Raja Ramanna Centre for Advanced Technology, Indore and Inter-University Accelerator Centre have jointly developed TESLA-type 1.3 GHz single cell cavities which have achieved very high accelerating gradients. Buoyed by the success of this work, a 5-cell 1.3 GHz cavity with simple end tubes has been successfully built. This cavity is presently at Fermi Lab for 2 K tests. Recently, a 650 MHz, β=0.9 single cell cavity has also been successfully completed and is ready for cold tests. There are plans to develop a 650 MHz, β=0.6 single cell cavity in collaboration with VECC, Kolkata. This paper presents the status of the niobium cavities developed at Inter-University Accelerator Centre. (author)

  6. Frequency-doubling optoelectronic oscillator based on destructive interference

    Science.gov (United States)

    Jiang, Jun; Chen, Fushen; Fan, Mengqiu; Li, Chengxin; Dong, Qimeng

    2015-12-01

    A frequency-doubling optoelectronic oscillator (OEO) using two cascaded modulators based on destructive interference is proposed and experimentally demonstrated. In the proposed system, we utilize a cascaded modulator including a phase modulator and an intensity modulator, which implements a carrier-suppressed double-sideband modulation based on destructive interference to generate a frequency-doubled microwave signal. Meanwhile, the phase modulator is connected by a chirp fiber Bragg grating in the loop, which forms a microwave photonic filter to select the fundamental frequency signal in the OEO loop. As a result, a frequency-doubled microwave signal at 17.9 and 20.5 GHz is generated, respectively. The phase noises and the long-term stability of the generated microwave signals are also investigated.

  7. Nonlinear frequency mixing in a resonant cavity: numerical simulations in a bubbly liquid.

    Science.gov (United States)

    Vanhille, Christian; Campos-Pozuelo, Cleofé; Sinha, Dipen N

    2014-12-01

    The study of nonlinear frequency mixing for acoustic standing waves in a resonator cavity is presented. Two high frequencies are mixed in a highly nonlinear bubbly liquid filled cavity that is resonant at the difference frequency. The analysis is carried out through numerical experiments, and both linear and nonlinear regimes are compared. The results show highly efficient generation of the difference frequency at high excitation amplitude. The large acoustic nonlinearity of the bubbly liquid that is responsible for the strong difference-frequency resonance also induces significant enhancement of the parametric frequency mixing effect to generate second harmonic of the difference frequency. PMID:25064635

  8. Frequency doubling and memory effects in the Spin Hall Effect

    OpenAIRE

    Pershin, Yu. V.; Di Ventra, M.

    2008-01-01

    We predict that when an alternating voltage is applied to a semiconducting system with inhomogeneous electron density in the direction perpendicular to main current flow, the spin Hall effect results in a transverse voltage containing a double-frequency component. We also demonstrate that there is a phase shift between applied and transverse voltage oscillations, related to the general memristive behavior of semiconductor spintronic systems. A different method to achieve frequency doubling ba...

  9. Mechanical design of RFQ resonator cavities in the 400-MHz frequency range

    International Nuclear Information System (INIS)

    Many RFQ resonator-cavity design concepts have been proposed in the 400-MHz frequency range. Los Alamos has been evaluating RFQ resonator-cavity designs that provide acceptable combinations of necessary mechanical features, easy tunability and long-term stability. Four RFQ resonator test cavities have been fabricated to test rf joints between the RFQ vanes and the resonator cavity. Two of these joints (the C-seal and the rf clamp-joint) allow vane movement for tuning. These test data, and the design of the present generation of RFQ resonator cavities, are presented

  10. Fundamental Frequency Tuning and Its Influence on LHC 200MHz ACN Cavity

    CERN Document Server

    Linnecar, Trevor Paul R; Tückmantel, Joachim; CERN. Geneva. SPS and LHC Division

    2001-01-01

    To study the influence of the tuner on the fundamental mode frequency, the Q factor as well as the shunt impedance of the LHC 200MHz ACN cavities, 3D simulations have been done in the frequency domain using MAFIA. Curves giving the variation of RF frequency and other RF parameters with tuner position relative to the inner surface of the cavity have been obtained for the fundamental mode. This paper details the simulation results.

  11. 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.

  12. Higher Order Mode Filter Design for Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B P; Ben-Zv, I; Burt, Graeme Campbell; Calaga, Rama; Capatina, Ofelia; Hall, B; Jones, T; Skaritka, J; Verdú-Andrés, S; Wu, Q

    2015-01-01

    A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multi-physics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.

  13. Higher order mode filter design for double quarter wave crab cavity for the LHC high luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Burt, G. [Lancaster Univ. (United Kingdom); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hall, B. [Lancaster Univ. (United Kingdom); Jones, T. [Science and Technology Facilities Council (STFC), Daresbury (United Kingdom). Daresbury Lab.; Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multiphysics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.

  14. Tunable Resonant-Cavity-Enhanced Photodetector with Double High-Index-Contrast Grating Mirrors

    DEFF Research Database (Denmark)

    Learkthanakhachon, Supannee; Yvind, Kresten; Chung, Il-Sug

    2013-01-01

    In this paper, we propose a broadband-tunable resonant-cavity-enhanced photodetector (RCE-PD) structure with double high-index-contrast grating (HCG) mirrors and numerically investigate its characteristics. The detector is designed to operate at 1550-nm wavelength. The detector structure consists...

  15. Negative and positive hysteresis in double-cavity optical bistability in three-level atom

    CERN Document Server

    Babu, H Aswath

    2010-01-01

    We present novel hysteretic behaviour of a three-level ladder atomic system exhibiting double-cavity optical bistability in the mean-field limit. The two fields coupling the atomic system experience feedback via two independent, unidirectional, single mode ring cavities and exhibit cooperative phenomena, simultaneously. The system displays a range of rich dynamical features varying from normal switching to self pulsing and a period-doubling route to chaos for both the fields. We focus our attention to a new hump like feature in the bistable curve arising purely due to cavity induced inversion, which eventually leads to negative hysteresis in the bistable response. This is probably the only all-optical bistable system that exhibits positive as well as negative bistable hysteresis in different input field intensity regimes. For both the fields, the switching times, the associated critical slowing down, the self-pulsing characteristics, and the chaotic behaviour can be controlled to a fair degree, moreover, all ...

  16. Multiorder nonlinear diffraction in frequency doubling processes

    DEFF Research Database (Denmark)

    Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw;

    2009-01-01

    We analyze experimentally light scattering from 2 nonlinear gratings and observe two types of second-harmonic frequency-scattering processes. The first process is identified as Raman–Nath type nonlinear diffraction that is explained by applying only transverse phase-matching conditions. The angular...

  17. Dual-wavelength high-power diode laser system based on an external-cavity tapered amplifier with tunable frequency difference

    DEFF Research Database (Denmark)

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

    2012-01-01

    A dual-wavelength high-power semiconductor laser system based on a tapered amplifier with double-Littrow external cavity is demonstrated around 800 nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 10.0 THz. To our knowle...

  18. Three-dimensional self-consistent simulations of multipacting in superconducting radio frequency cavities. Final Report

    International Nuclear Information System (INIS)

    Superconducting radio frequency (SRF) cavities are a popular choice among researchers designing new accelerators because of the reduced power losses due to surface resistance. However, SRF cavities still have unresolved problems, including the loss of power to stray electrons. Sources of these electrons are field emission from the walls and ionization of background gas, but the predominant source is secondary emission yield (SEY) from electron impact. When the electron motion is in resonance with the cavity fields the electrons strike the cavity surface repeatedly creating a resonant build up of electrons referred to as multipacting. Cavity shaping has successfully reduced multipacting for cavities used in very high energy accelerators. However, multipacting is still a concern for the cavity power couplers, where shaping is not possible, and for cavities used to accelerate particles at moderate velocities. This Phase II project built upon existing models in the VORPAL simulation framework to allow for simulations of multipacting behavior in SRF cavities and their associated structures. The technical work involved allowed existing models of secondary electron generation to work with the complex boundary conditions needed to model the cavity structures. The types of data produced by VORPAL were also expanded to include data common used by cavity designers to evaluate cavity performance. Post-processing tools were also modified to provide information directly related to the conditions that produce multipacting. These new methods were demonstrated by running simulations of a cavity design being developed by researchers at Jefferson National Laboratory to attempt to identify the multipacting that would be an issue for the cavity design being considered. These simulations demonstrate that VORPAL now has the capabilities to assist researchers working with SRF cavities to understand and identify possible multipacting issues with their cavity designs.

  19. Three-dimensional self-consistent simulations of multipacting in superconducting radio frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Chet Nieter

    2010-12-01

    Superconducting radio frequency (SRF) cavities are a popular choice among researchers designing new accelerators because of the reduced power losses due to surface resistance. However, SRF cavities still have unresolved problems, including the loss of power to stray electrons. Sources of these electrons are field emission from the walls and ionization of background gas, but the predominant source is secondary emission yield (SEY) from electron impact. When the electron motion is in resonance with the cavity fields the electrons strike the cavity surface repeatedly creating a resonant build up of electrons referred to as multipacting. Cavity shaping has successfully reduced multipacting for cavities used in very high energy accelerators. However, multipacting is still a concern for the cavity power couplers, where shaping is not possible, and for cavities used to accelerate particles at moderate velocities. This Phase II project built upon existing models in the VORPAL simulation framework to allow for simulations of multipacting behavior in SRF cavities and their associated structures. The technical work involved allowed existing models of secondary electron generation to work with the complex boundary conditions needed to model the cavity structures. The types of data produced by VORPAL were also expanded to include data common used by cavity designers to evaluate cavity performance. Post-processing tools were also modified to provide information directly related to the conditions that produce multipacting. These new methods were demonstrated by running simulations of a cavity design being developed by researchers at Jefferson National Laboratory to attempt to identify the multipacting that would be an issue for the cavity design being considered. These simulations demonstrate that VORPAL now has the capabilities to assist researchers working with SRF cavities to understand and identify possible multipacting issues with their cavity designs.

  20. Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S. B., E-mail: sbroy@rrcat.gov.in [Magnetic & Superconducting Materials Section, Materials & Advanced Accelerator Sciences Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Myneni, G. R., E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, Virginia (United States)

    2015-12-04

    We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other related material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values.

  1. Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

    International Nuclear Information System (INIS)

    We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other related material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values

  2. Selective engineering of cavity resonance for frequency matching in optical parametric processes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiyuan; Rogers, Steven [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Jiang, Wei C. [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Lin, Qiang, E-mail: qiang.lin@rochester.edu [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627 (United States)

    2014-10-13

    We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.

  3. Selective engineering of cavity resonance for frequency matching in optical parametric processes

    CERN Document Server

    Lu, Xiyuan; Jiang, Wei C; Lin, Qiang

    2014-01-01

    We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.

  4. Resonance frequencies of a cavity containing a compressible viscous fluid

    Science.gov (United States)

    Conca, C.; Planchard, J.; Vanninathan, M.

    1993-03-01

    The aim of this paper is to study the resonance spectrum of a cavity containing a compressible viscous fluid. This system admits a discrete infinite sequence of eigenvalues whose real parts are negative, which is interpreted as the damping effect introduced by viscosity. Only a finite number of them have non-zero imaginary parts and this number depends on viscosity; a simple criterion is given for their position in the complex plane. The case of a cavity containing an elastic mechanical system immersed in the fluid is also examined; from a qualitative point of view, the nature of the resonance spectrum remains unchanged.

  5. Double Fano resonances in nanoring cavity dimers: The effect of plasmon hybridization between dark subradiant modes

    Directory of Open Access Journals (Sweden)

    Li-Yan Yin

    2014-07-01

    Full Text Available Dark mode which is subradiant plays a key role in the generation of Fano effect. This study proposes that plasmon interaction between dark modes is a favorable method to generate multiple Fano resonances, where plasmon hybridization leads to the formation of a subradiant bonding and a subradiant antibonding combination. It demonstrates that a concentric ring/ring cavity dimer introduces interactions that render bonding quadrupolar ring mode dipole active, resulting in a pronounced Fano resonance. The corresponding antibonding quadrupolar ring mode is excited in a symmetry breaking nonconcentric cavity dimer, and double Fano resonances appear in the spectra.

  6. Partial heating and partial salting on double-diffusive convection in an open cavity

    Science.gov (United States)

    Arbin, N.; Hashim, I.

    2014-09-01

    Double-diffusive natural convection in an open top square cavity and partially heated from the side is studied numerically. Constant temperatures and concentration are imposed along the right and left walls while the heat balance at the surface is assumed to obey Newton's law of cooling. The finite difference method is used to solve the dimensionless governing equations. The numerical results are reported for the effects of Marangoni number and different heater locations on the contours of streamlines, temperature and concentration. The heat and mass transfer rate in the cavity are measured in terms of the average Nusselt and Sherwood numbers.

  7. Tunable two-photon correlation in a double-cavity optomechanical system

    Directory of Open Access Journals (Sweden)

    Zhi-Bo Feng

    2015-12-01

    Full Text Available Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity.

  8. Tunable two-photon correlation in a double-cavity optomechanical system

    International Nuclear Information System (INIS)

    Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity

  9. A method to measure the frequencies of individual half cells in a dumbbell cavity.

    Science.gov (United States)

    An, Sun; Liping, Zhang; Yazhe, Tang; Li, Ying-min; Cho, Yong-Sub

    2008-10-01

    Dumbbell fabrication is a midprocess for manufacturing an elliptical superconducting rf cavity. In order to understand how a welding shrinkage affects a dumbbell's frequencies and length, we need to measure the exact frequencies of each individual half cell of a dumbbell. To improve such a calculation precision and to simplify the calculation formulae, based on a two-coupled oscillator model and a cavity perturbation theory, a new formula to calculate the individual half-cell frequencies of a dumbbell or the individual cavity frequencies of a two-cavity coupling system has been developed, and its performance has been confirmed by using a dumbbell simulation. This formula can be applied to any kind of rf cavities with electric, magnetic, or electromagnetic coupling, if a coupling hole between two coupling cavities is small compared to the wavelength. Compared to other calculation formulae, this formula simplifies the calculation process of the individual resonator frequencies of a coupling system considerably, and it can also improve the calculation precision than that of a normal calculation method. Another advantage of this new method is that we do not need to consider a coupling factor between two resonators during a testing for an individual resonator frequency of an oscillator. The developed formula has been successfully used to tune the PEFP dumbbells.

  10. Compact infrared continuous-wave double-pass single-frequency doubly-resonant OPO

    CERN Document Server

    Boucon, Anne; Bretenaker, Fabien

    2014-01-01

    We demonstrate a compact continuous-wave single-frequency doubly-resonant optical parametric oscillator (DRO) in a double-pass pump configuration with a control of the relative phase between the reflected waves. The nested DRO cavity allows single longitudinal mode operation together with low threshold and high efficiency. Thermal effects are managed by chopping the pump beam, allowing continuous tuning of the emitted wavelength. The infrared idler wave (3200-3800 nm) can be used for gas detection and the threshold pump power is compatible with diode pumping.

  11. High power frequency doubled GaInNAs semiconductor disk laser emitting at 615 nm.

    Science.gov (United States)

    Härkönen, Antti; Rautiainen, Jussi; Guina, Mircea; Konttinen, Janne; Tuomisto, Pietari; Orsila, Lasse; Pessa, Markus; Okhotnikov, Oleg G

    2007-03-19

    We report on an optically-pumped intracavity frequency doubled GaInNAs/GaAs -based semiconductor disk laser emitting around 615 nm. The laser operates at fundamental wavelength of 1230 nm and incorporates a BBO crystal for light conversion to the red wavelength. Maximum output power of 172 mW at 615 nm was achieved from a single output. Combined power from two outputs was 320 mW. The wavelength of visible emission could be tuned by 4.5 nm using a thin glass etalon inside the cavity.

  12. High power frequency doubled GaInNAs semiconductor disk laser emitting at 615 nm.

    Science.gov (United States)

    Härkönen, Antti; Rautiainen, Jussi; Guina, Mircea; Konttinen, Janne; Tuomisto, Pietari; Orsila, Lasse; Pessa, Markus; Okhotnikov, Oleg G

    2007-03-19

    We report on an optically-pumped intracavity frequency doubled GaInNAs/GaAs -based semiconductor disk laser emitting around 615 nm. The laser operates at fundamental wavelength of 1230 nm and incorporates a BBO crystal for light conversion to the red wavelength. Maximum output power of 172 mW at 615 nm was achieved from a single output. Combined power from two outputs was 320 mW. The wavelength of visible emission could be tuned by 4.5 nm using a thin glass etalon inside the cavity. PMID:19532562

  13. Preparation and handling of surfaces for superconducting radio frequency cavities

    International Nuclear Information System (INIS)

    Fortunately, surface treatment for s.c. cavities knows only one simple rule. If one observes this rule strictly one will be successful, if not, one will fail! The rule is CLEANLINESS. This means: clean material (high purity niobium without inclusions), clean (analytical grade) polishing chemicals and solvents, ultraclean (semiconductor grade) rinsing water, ultraclean (class 100) assembly environment. In general, if one applies the same working practice as the semiconductor industry, one will produce surfaces that are less clean than silicon wafers, due to the shape of the cavity (an inner surface is much more difficult to clean than a flat wafer); due to its size and due to the material (niobium is hydrophilic which makes the water with all the dirt in it stick to the surface). 9 references

  14. Enhanced terahertz source based on external cavity difference-frequency generation using monolithic single-frequency pulsed fiber lasers.

    Science.gov (United States)

    Petersen, Eliot B; Shi, Wei; Nguyen, Dan T; Yao, Zhidong; Zong, Jie; Chavez-Pirson, Arturo; Peyghambarian, N

    2010-07-01

    We demonstrate a resonant external cavity approach to enhance narrowband terahertz radiation through difference-frequency generation for the first time (to our knowledge). Two nanosecond laser pulses resonant in an optical cavity interact with a nonlinear crystal to produce a factor of 7 enhancement of terahertz power compared to a single-pass orientation. This external enhancement approach shows promise to significantly increase both terahertz power and conversion efficiency through optical pump pulse enhancement and effective recycling. PMID:20596183

  15. Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Carlos [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.; Xiao, B. P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.

    2014-06-01

    The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.

  16. Hyperparallel optical quantum computation assisted by atomic ensembles embedded in double-sided optical cavities

    Science.gov (United States)

    Li, Tao; Long, Gui-Lu

    2016-08-01

    We propose an effective, scalable, hyperparallel photonic quantum computation scheme in which photonic qubits are hyperencoded both in the spatial degrees of freedom (DOF) and the polarization DOF of each photon. The deterministic hyper-controlled-not (hyper-cnot) gate on a two-photon system is attainable with our interesting interface between the polarized photon and the collective spin wave (magnon) of an atomic ensemble embedded in a double-sided optical cavity, and it doubles the operations in the conventional quantum cnot gate. Moreover, we present a compact hyper-cnotN gate on N +1 hyperencoded photons with only two auxiliary cavity-magnon systems, not more, and it can be faithfully constituted with current experimental techniques. Our proposal enables various applications with the hyperencoded photons in quantum computing and quantum networks.

  17. Cavity-enhanced single frequency synthesis via DFG of mode-locked pulse trains

    OpenAIRE

    Ferrari, Gabriele; Carusotto, Iacopo

    2005-01-01

    We show how to synthesize a CW, single-frequency optical field from the frequency-dispersed, pulsed field of a mode-locked laser. This process, which relies on difference frequency generation in an optical cavity, is efficient and can be considered as an optical rectification. Quantitative estimates for the output power and amplitude noise properties of a realistic system are given. Possible applications to optical frequency synthesis and optical metrology are envisaged.

  18. Experimental investigation of combustion mechanisms of kerosene-fueled scramjet engines with double-cavity flameholders

    Institute of Scientific and Technical Information of China (English)

    Yu Pan; Jian-Guo Tan; Jian-Han Liang; Wei-Dong Liu; Zhen-Guo Wang

    2011-01-01

    A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M =2.64,Pt =1.84 MPa,Tt =1 300 K.Successful ignition and selfsustained combustion with room temperature kerosene was achieved using pilot hydrogen,and kerosene was vertically injected into the combustor through 4×φ0.5 mm holes mounted on the wall.For different equivalence ratios and different injection schemes with both tandem cavities and parallel cavities,flow fields were obtained and compared using a high speed camera and a Schlieren system.Results revealed that the combustor inside the flow field was greatly influenced by the cavity installation scheme,cavities in tandem easily to form a single side flame distribution,and cavities in parallel are more likely to form a joint flame,forming a choked combustion mode.The supersonic combustion flame was a kind of diffusion flame and there were two kinds of combustion modes.In the unchoked combustion mode,both subsonic and supersonic combustion regions existed.While in the choked mode,the combustion region was fully subsonic with strong shock propagating upstream.Results also showed that there was a balance point between the boundary separation and shock enhanced combustion,depending on the intensity of heat release.

  19. Cooling the APS storage ring radio-frequency accelerating cavities: Thermal/stress/fatigue analysis and cavity cooling configuration

    International Nuclear Information System (INIS)

    The 7-GeV Advanced Photon Source positron storage ring requires sixteen separate 352-MHz radio-frequency (rf) accelerating cavities. Cavities are installed as groups of four, in straight sections used elsewhere for insertion devices. They occupy the first such straight section after injection, along with the last three just before injection. Cooling is provided by a subsystem of the sitewide deionized water system. Pumping equipment is located in a building directly adjacent to the accelerator enclosure. A prototype cavity was fabricated and tested where cooling was via twelve 19-mm-diameter [3/4 in] brazed-on tubes in a series-parallel flow configuration. Unfortunately, the thermal contact to some tubes was poor due to inadequate braze filler. Here, heat transfer studies, including finite-element analysis and test results, of the Advanced Photon Source (APS) storage ring 352-MHz rf accelerating cavities are described. Stress and fatigue life of the copper are discussed. Configuration of water cooling is presented

  20. Experimental observation of coherent cavity soliton frequency combs in silica microspheres

    CERN Document Server

    Webb, Karen E; Coen, Stéphane; Murdoch, Stuart G

    2016-01-01

    We report on the experimental observation of coherent cavity soliton frequency combs in silica microspheres. Specifically, we demonstrate that careful alignment of the microsphere relative to the coupling fiber taper allows for the suppression of higher-order spatial modes, reducing mode interactions and enabling soliton formation. Our measurements show that the temporal cavity solitons have sub-100-fs durations, exhibit considerable Raman self-frequency shift, and generally come in groups of three or four, occasionally with equidistant spacing in the time domain. RF amplitude noise measurements and spectral interferometry confirm the high coherence of the observed soliton frequency combs, and numerical simulations show good agreement with experiments.

  1. Frequency dependence of the acoustic field generated from a spherical cavity transducer with open ends

    Energy Technology Data Exchange (ETDEWEB)

    Li, Faqi; Zeng, Deping; He, Min; Wang, Zhibiao, E-mail: dzhang@nju.edu.cn, E-mail: wangzhibiao@haifu.com.cn [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing 401121 (China); Song, Dan; Lei, Guangrong [National Engineering Research Center of Ultrasound Medicine, Chongqing 401121 (China); Lin, Zhou; Zhang, Dong, E-mail: dzhang@nju.edu.cn, E-mail: wangzhibiao@haifu.com.cn [Institute of Acoustics, Key Laboratory of Modern Acoustics, MOE, Nanjing University, Nanjing 210093 (China); Wu, Junru [Department of Physics, University of Vermont, Burlington, VT 05405 (United States)

    2015-12-15

    Resolution of high intensity focused ultrasound (HIFU) focusing is limited by the wave diffraction. We have developed a spherical cavity transducer with two open ends to improve the focusing precision without sacrificing the acoustic intensity (App Phys Lett 2013; 102: 204102). This work aims to theoretically and experimentally investigate the frequency dependence of the acoustic field generated from the spherical cavity transducer with two open ends. The device emits high intensity ultrasound at the frequency ranging from 420 to 470 kHz, and the acoustic field is measured by a fiber optic probe hydrophone. The measured results shows that the spherical cavity transducer provides high acoustic intensity for HIFU treatment only in its resonant modes, and a series of resonant frequencies can be choosen. Furthermore, a finite element model is developed to discuss the frequency dependence of the acoustic field. The numerical simulations coincide well with the measured results.

  2. Nanostructural features affecting superconducting radio frequency niobium cavities revealed using TEM and EELS

    CERN Document Server

    Trenikhina, Y; Kwon, J; Zuo, J -M; Zasadzinski, J F

    2015-01-01

    Nanoscale defect structure within the magnetic penetration depth of ~100nm is key to the performance limitations of niobium superconducting radio frequency (SRF) cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120C baking. Furthermore, we demonstrate that adding 800C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120C bake.

  3. Manipulating the optical bistability at terahertz frequency in the Fabry-Perot cavity with graphene.

    Science.gov (United States)

    Jiang, Leyong; Guo, Jun; Wu, Leiming; Dai, Xiaoyu; Xiang, Yuanjiang

    2015-11-30

    We investigate theoretically the optical bistability from a Fabry-Perot cavity with graphene in the terahertz (THz) frequency. It is demonstrated that the optical bistablility in this cavity can be realized due to the electric field enhancement and the giant third-order nonlinear conductivity of graphene. The optical bistable behavior is strongly dependent on the transmission amplitude of the mirror and the position of the graphene in the cavity. It is especially important that the hysterical behaviors of the transmitted light rely on the optical conductivity of graphene, making the Fabry-Perot cavity to be a good candidate for dynamic tunable optical bistable device in the THz frequencies, owing to the possibility of high tunability of graphene conductivity by means of external electrostatic or magnetostatic field.

  4. Frequency splitting of polarization eigenmodes in microscopic Fabry-Perot cavities

    CERN Document Server

    Uphoff, Manuel; Rempe, Gerhard; Ritter, Stephan

    2014-01-01

    We study the frequency splitting of the polarization eigenmodes of the fundamental transverse mode in CO2 laser-machined, high-finesse optical Fabry-Perot cavities and investigate the influence of the geometry of the cavity mirrors. Their highly reflective surfaces are typically not rotationally symmetric, but have slightly different radii of curvature along two principal axes. We observe that the eccentricity of such elliptical mirrors lifts the degeneracy of the polarization eigenmodes. The impact of the eccentricity increases for smaller radii of curvature. A model derived from corrections to the paraxial resonator theory is in excellent agreement with measurements, showing that geometric effects are the main source of the frequency splitting of polarization modes for the studied type of microscopic cavity. By rotation of one of the mirrors around the cavity axis, the splitting can be tuned. In the case of an identical differential phase shift per mirror it can even be eliminated, despite a nonvanishing ec...

  5. Tunable femtosecond laser in the visible range with an intracavity frequency-doubled optical parametric oscillator

    Science.gov (United States)

    Zhu, Jiang-Feng; Xu, Liang; Lin, Qing-Feng; Zhong, Xin; Han, Hai-Nian; Wei, Zhi-Yi

    2013-05-01

    We demonstrated experimentally a synchronously pumped intracavity frequency-doubled femtosecond optical parametric oscillator (OPO) using a periodically-poled lithium niobate (PPLN) as the nonlinear material in combination with a lithium triborate (LBO) as the doubling crystal. A Kerr-lens-mode-locked (KLM) Ti:sapphire oscillator at the wavelength of 790 nm was used as the pump source, which was capable of generating pulses with a duration as short as 117 fs. A tunable femtosecond laser covering the 624-672 nm range was realized by conveniently adjusting the OPO cavity length. A maximum average output power of 260 mW in the visible range was obtained at the pump power of 2.2 W, with a typical pulse duration of 205 fs assuming a sech2 pulse profile.

  6. A widely tunable double-Brillouin-frequency spaced multiwavelength fiber laser with a 110 nm tuning range

    International Nuclear Information System (INIS)

    A wideband double-Brillouin-frequency spaced multiwavelength Brillouin–erbium fiber laser (MWBEFL) with 110 nm tuning range is demonstrated. The fiber laser utilizes simple compound-ring cavity structures which confine the odd-order Brillouin–Stokes (BS) signals within the right ring and couple out the initial Brillouin pump signal (BP) and even-order BS signals to generate a 0.176 nm spacing multiwavelength. A wavelength- and bandwidth-tunable optical band-pass filter (TBF) is used to manipulate the location of self-lasing cavity and to get a wideband tuning range. All the generated output channels exhibit good stability. (paper)

  7. Design of radio-frequency cavities and Tera-Hertz electron injectors for advanced applications

    Energy Technology Data Exchange (ETDEWEB)

    Seyedfakhari, Seyedmoein

    2016-06-15

    Design of three accelerator components including a buncher cavity for REGAE, a normal conducting cavity for arrival time stabilization at FLASH and ultra-fast guns for the AXSIS project is presented in this thesis. Using RF cavities caused a revolution in accelerators and made it possible to generate high energy particle beams. In advanced accelerators, cavities are not only used to increase the particle energy but they are also widely used to improve the beam quality and additionally for beam diagnostic purposes. In the present dissertation, such applications are discussed. First, design of a buncher cavity which compresses the bunch at the REGAE facility is presented. The design pursues improving the mode separation of the cavity. The simulation result illustrates that the difference between the operating mode and its adjacent mode has been increased from 2 MHz for the existing cavity to 9.5 MHz for the new design. In the second part, a normal conducting cavity is discussed, which will be used to regulate the arrival time ofthe bunches at FLASH and at the European XFEL. The designed cavity is able to correct the arrival time jitter of ± 150 fs in order to provide femtosecond precision synchronization between the electron beam and the external laser pulses. Thermal, wakefield and multipacting simulations have also been performed for the designed cavity in order to evaluate its operation efficiency. In advanced accelerators however RF cavities should be replaced by novel structures to accelerate the particles in shorter distances using higher operating frequency. To this end, ultra-fast guns are designed which will be discussed in the last part of this work. The designed guns accelerate the electrons from their rest mass up to 2 MeV using a single cycle THz signal with a total energy of 2 mJ.

  8. Cavity-Enhanced Frequency-Agile Rapid Scanning (fars) Spectroscopy: Measurement Principles

    Science.gov (United States)

    Hodges, Joseph T.; Long, David A.; Truong, Gar-Wing; Douglass, Kevin O.; Maxwell, Stephen E.; Zee, Roger Van; Plusquellic, David F.

    2013-06-01

    We present the principles of frequency-agile, rapid scanning (FARS) spectroscopy, a new technique for high-bandwidth, cavity-enhanced, laser absorption measurements. This method enables a visible or near-infrared probe laser beam to be frequency tuned over several tens of GHz using a microwave source, a waveguide phase modulator and a filter cavity. For the types of cavity-enhanced methods discussed here, the optical resonator itself is used to select a single sideband of the modulated laser spectrum, obviating the need for a separate filter cavity. FARS offers several important advantages over conventional cw laser tuning methods based on thermal or mechanical methods. These include, high speed tuning with sub-ms switching times, the ability to select arbitrary frequency steps or chirp rates, and the realization of a spectrum detuning axis with sub-kHz level precision. We discuss how FARS can be applied to cavity ring-down spectroscopy and other cavity-enhanced methods to enable rapid and accurate measurements of line parameters and to give noise-equivalent absorption coefficients at the 10^{-12} cm^{-1} Hz^{-1/2} level.

  9. Cavities

    Science.gov (United States)

    ... the bacteria produce acids that cause decay. Tooth pain occurs after decay reaches the inside of the tooth. Dentists can detect cavities by examining the teeth and taking x-rays periodically. Good oral hygiene and regular dental care plus a healthy diet can help prevent cavities. ...

  10. 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...

  11. Design of Chaotic Cavities with Curved Wave Diffractors for Enhanced Low-Frequency Operation

    CERN Document Server

    Arnaut, L R

    2014-01-01

    Some numerical calculations are presented on the dependence of the average mode count and average mode density of electromagnetic cavities on their specific geometric design, based on the generalized Weyl law. The analysis focuses on a chaotic quasi-cubic cavity furnished with curved wave diffractors placed on its interior surface. The focus is on a design that increases the mode density and Q at relatively low frequencies. The results are of interest in reducing the `lowest usable frequency' and increasing the maximum field strength inside mode-stirred reverberation chambers.

  12. 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.

  13. Hybrid Physical Chemical Vapor Deposition of Superconducting Magnesium Diboride Coatings for Large Scale Radio Frequency Cavities

    Science.gov (United States)

    Lee, Namhoon; Withanage, Wenura; Tan, Teng; Wolak, Matthaeus; Xi, Xiaoxing

    2016-03-01

    Magnesium diboride (MgB2) is considered to be a great candidate for next generation superconducting radio frequency (SRF) cavities due to its higher critical temperature Tc (40 K) and increased thermodynamic critical field Hc compared to other conventional superconductors. These properties significantly reduce the BCS surface resistance (RsBCS)and residual resistance (Rres) according to theoretical studies and suggest the possibility of an enhanced accelerating field (Eacc) . We have investigated the possibility of coating the inner surface of a 3 GHz SRF cavity with MgB2 by using a hybrid physical-vapor deposition (HPCVD) system which was modified for this purpose. To simulate a real 3 GHz SRF cavity, a stainless steel mock cavity has been employed for the study. The film quality was characterized on small substrates that were placed at selected locations within the cavity. MgB2 films on stainless steel foils, niobium pieces and SiC substrates showed transition temperatures of above 36 K. Dielectric resonance measurements resulted in promising Q values as obtained for the MgB2 films grown on the various substrates. By employing the HPCVD technique, a uniform film was achieved across the cavity interior, demonstrating the feasibility of HPCVD for MgB2 coatings for SRF cavities.

  14. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    OpenAIRE

    WEN, Xin; Han, Yashuai; Wang, Junmin

    2016-01-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power ...

  15. Flux pinning characteristics in cylindrical ingot niobium used in superconducting radio frequency cavity fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Dhavale Ashavai, Pashupati Dhakal, Anatolii A Polyanskii, Gianluigi Ciovati

    2012-04-01

    We present the results of from DC magnetization and penetration depth measurements of cylindrical bulk large-grain (LG) and fine-grain (FG) niobium samples used for the fabrication of superconducting radio frequency (SRF) cavities. The surface treatment consisted of electropolishing and low temperature baking as they are typically applied to SRF cavities. The magnetization data were fitted using a modified critical state model. The critical current density Jc and pinning force Fp are calculated from the magnetization data and their temperature dependence and field dependence are presented. The LG samples have lower critical current density and pinning force density compared to FG samples which implies a lower flux trapping efficiency. This effect may explain the lower values of residual resistance often observed in LG cavities than FG cavities.

  16. Flux pinning characteristics in cylindrical ingot niobium used in superconducting radio frequency cavity fabrication

    CERN Document Server

    Dhavale, Asavari S; Polyanskii, Anatolii A; Ciovati, Gianluigi

    2012-01-01

    We present the results of from DC magnetization and penetration depth measurements of cylindrical bulk large-grain (LG) and fine-grain (FG) niobium samples used for the fabrication of superconducting radio frequency (SRF) cavities. The surface treatment consisted of electropolishing and low temperature baking as they are typically applied to SRF cavities. The magnetization data were fitted using a modified critical state model. The critical current density Jc and pinning force Fp are calculated from the magnetization data and their temperature dependence and field dependence are presented. The LG samples have lower critical current density and pinning force density compared to FG samples which implies a lower flux trapping efficiency. This effect may explain the lower values of residual resistance often observed in LG cavities than FG cavities.

  17. Double-diamond high-contrast-gratings vertical external cavity surface emitting laser

    International Nuclear Information System (INIS)

    A new design of vertical external cavity surface emitting laser (VECSEL) with diamond-based high contrast gratings is proposed. The self-consistent model of laser operation has been calibrated based on experimental results and used to optimize the new proposed device and to perform comparative thermal and optical analysis of conventional and double-diamond high-contrast-grating VECSELs. The proposed design considerably reduces the dimensions and complexity of the device and provides up to 80% increase of the maximum emitted power as compared with the conventional design. (paper)

  18. Entanglement evolution and transfer in a double Tavis-Cumming model in cavity QED

    Institute of Scientific and Technical Information of China (English)

    Xu Qing-Jun; Zhang Shi-Ying

    2009-01-01

    We have studied entanglement evolution and transfer in a double Tavis-Cumming model where two pairs of entangled two-level atoms AB and CD interact with two single-mode cavity fields a and b. We show that the Bell-like initial state of atoms AB can exhibit entanglement sudden death which should be independent of the initial entanglement of atoms CD. Also, we show that the initial entanglement of one atomic pair can he transferred into another pair, as well as the possible subsystems, that become entangled during evolution.

  19. Summary of performance of superconducting radio-frequency cavities built from CBMM niobium ingots

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi, E-mail: gciovati@jlab.org; Dhakal, Pashupati, E-mail: dhakal@jlab.org; Kneisel, Peter, E-mail: kneisel@jlab.org; Myneni, Ganapati R., E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

    2015-12-04

    Several Nb ingots have been provided by CBMM to Jefferson Lab since 2004 as part of an R&D collaboration aimed at evaluating the performance of superconducting radio-frequency cavities built from ingots with different purity, as a results of different ingot production processes. Approximately 32 multi- and single-cell cavities with resonant frequency between ∼1.3-2.3 GHz were built, treated and tested at 2 K at Jefferson Lab between 2004 and 2014. The average peak surface field achieved in cavities made of RRR∼260 and RRR∼100-150 ingots was (119 ± 4) mT and (100 ± 8) mT, respectively. Higher quality factor values at 2.0 K have been measured in medium-purity, compared to higher purity material.

  20. Using Frequency Noise Feedback to Improve Stability in Extended Cavity Diode Lasers

    Science.gov (United States)

    Pugh, Mckinley; Durfee, Dallin

    2016-03-01

    We are developing a feedback system to stabilize extended cavity diode lasers using frequency noise. In other literature, amplitude noise has been used to predict and prevent mode hops. We've found, however, that amplitude noise only correlates to an impending mode hop when the laser is locked to a frequency reference. We have found evidence that the amplitude noise is generated from more fundamental frequency noise by the lock feedback. We therefore propose a way to use frequency noise directly to generate a signal to predict and prevent mode hops.

  1. 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.

  2. Flight-Like Optical Reference Cavity for GRACE Follow-On Laser Frequency Stabilization

    Science.gov (United States)

    Folkner, W. M.; deVine, G.; Klipstein, W. M.; McKenzie, K.; Spero, R.; Thompson, R.; Yu, N.; Stephens, M.; Leitch, J.; Pierce, R.; Shaddock, D.; Lam, T.

    2011-01-01

    We describe a prototype optical cavity and associated optics that has been developed to provide a stable frequency reference for a future space-based laser ranging system. This instrument is being considered for inclusion as a technology demonstration on the recently announced GRACE follow-on mission, which will monitor variations in the Earth's gravity field.

  3. Continuous Vernier filtering of an optical frequency comb for broadband cavity-enhanced molecular spectroscopy

    CERN Document Server

    Rutkowski, Lucile

    2016-01-01

    We have recently introduced the Vernier-based Direct Frequency Comb Cavity-Enhanced Spectroscopy technique and we present the corresponding formalism for quantitative broadband spectroscopy. We achieve high sensitivity and broadband performance by acquiring spectra covering more than 2000 cm$^{-1}$ around 12600 cm$^{-1}$ (800 nm), resolving the 3$\

  4. Frequency-temperature compensated sapphire loaded cavity for compact hydrogen masers

    International Nuclear Information System (INIS)

    We report some theoretical and experimental results about a frequency-temperature compensated sapphire loaded cavity for compact hydrogen maser atomic clocks. Based on theoretical calculations, the frequency-temperature coefficients in the TE011 mode of a sapphire cavity associated with two small rings of SrTiO3 can be reduced. For instance, at 50 C, when the thickness of the SrTiO3 ring is 5 mm, the frequency-temperature coefficient can be reduced by about five times, and in the meantime, the quality factor can be kept at above 40 000 synchronously. A sapphire loaded cavity and eight small compensated chips of SrTiO3 were prepared and a combined cavity of sapphire with SrTiO3 chips was simulated by the finite element method and measured by experiments. The simulation and the related experimental results agree well. In addition, the frequency-temperature coefficients in two different configurations of eight SrTiO3 chips were also measured and compared. (authors)

  5. Resonance frequency shift in a cavity with a thin conducting film near a conducting wall

    Energy Technology Data Exchange (ETDEWEB)

    Braggio, C. [Dipartimento di Fisica, Universita di Ferrara and INFN, Via del Paradiso 12, 44100 Ferrara (Italy)]. E-mail: caterina.braggio@lnl.infn.it; Bressi, G. [INFN, Sezione di Pavia, Via Bassi 6, 27100 Pavia (Italy); Carugno, G. [INFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova (Italy); Dodonov, A.V. [Departamento de Fisica, Universidade Federal de Sao Carlos, Via Washington Luiz, Km 235, Sao Carlos 13565-905, SP (Brazil); Dodonov, V.V. [Instituto de Fisica, Universidade de Brasilia, Caixa Postal 04455, 70910-900 Brasilia, DF (Brazil)]. E-mail: vdodonov@fis.unb.br; Galeazzi, G. [INFN, LNL, Viale dell' Universita 2, 35020 Legnaro (Italy); Ruoso, G. [INFN, LNL, Viale dell' Universita 2, 35020 Legnaro (Italy); Zanello, D. [INFN, Sezione di Roma, Piazzale A. Moro 2, 00185 Roma (Italy)

    2007-03-19

    We show that a very thin conducting film (whose thickness can be much smaller than the skin depth), placed nearby a wall of an electromagnetic cavity, can produce the same shift of the resonance frequency as a bulk conducting slab, provided the displacement of the film from the wall is much bigger than the skin depth. We derive a simple analytical formula for the frequency shift and compare it with exact numerical calculations and experimental data.

  6. Precise force measurement method by a Y-shaped cavity dual-frequency laser

    Institute of Scientific and Technical Information of China (English)

    Guangzong Xiao; Xingwu Long; Bin Zhang; Geng Li

    2011-01-01

    A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed. The principle of force measurement with this method is analyzed, and the analytic relation expression between the input force and the change in the output beat frequency is derived. Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed; they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range. The maximum scale factor is observed as 5.02×109 Hz/N, with beat frequency instability equivalent resolution of 10-5 N. By optimizing the optical and geometrical parameters of the laser sensor, a force measurement resolution of 10-6i N could be expected.%A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed.The principle of force measurement with this method is analyzed,and the analytic relation expression between the input force and the change in the output beat frequency is derived.Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed;they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range.The maximum scale factor is observed as 5.02× 109 Hz/N,with beat frequency instability equivalent resolution of 10-5 N.By optimizing the optical and geometrical parameters of the laser sensor,a force measurement resolution of 10 -6 N could be expected.Precise measurement of force and force-related nagnitudes,such as acceleration,pressure,and mass,is an often demanded task in modern engineering and science[1-3].In recent decades,some research efforts have been intensified to utilize optical measnrement procedures for obtaining precise force measurement.

  7. Spread of smoke and heat along narrow air cavity in double-skin façade fires

    Directory of Open Access Journals (Sweden)

    Chow Lun Cheuk

    2014-01-01

    Full Text Available A scenario on double-skin façade fire was identified earlier for hazard assessment. A flashover room fire occurred next to the façade, broke the interior glass pane and spread to the façade cavity. As observed in experiments, hot gas moved up as a vertical channel flow for narrow façade cavity. Heat and smoke spread along the narrow air cavity of a double-skin façade will be studied in this paper. A simple mathematical model is developed from basic heat transfer theory for studying the vertical air temperature profiles of the hot gas flowing along the cavity. Assuming one-dimensional flow for hot gas moving up the façade cavity, conservation equations on mass and enthalpy were solved. Experimental results on two double-skin façade rigs of height 6 m and 15 m with narrow cavity depth were used to justify the results. A total of 11 tests were carried out. Correlation expressions between cavity air temperature and the height above ceiling of the fire room were derived.

  8. Surface analyses of electropolished niobium samples for superconducting radio frequency cavity

    International Nuclear Information System (INIS)

    The performance of superconducting radio frequency niobium cavities is sometimes limited by contaminations present on the cavity surface. In the recent years extensive research has been done to enhance the cavity performance by applying improved surface treatments such as mechanical grinding, electropolishing (EP), chemical polishing, tumbling, etc., followed by various rinsing methods such as ultrasonic pure water rinse, alcoholic rinse, high pressure water rinse, hydrogen per oxide rinse, etc. Although good cavity performance has been obtained lately by various post-EP cleaning methods, the detailed nature about the surface contaminants is still not fully characterized. Further efforts in this area are desired. Prior x-ray photoelectron spectroscopy (XPS) analyses of EPed niobium samples treated with fresh EP acid, demonstrated that the surfaces were covered mainly with the niobium oxide (Nb2O5) along with carbon, in addition a small quantity of sulfur and fluorine were also found in secondary ion mass spectroscopy (SIMS) analysis. In this article, the authors present the analyses of surface contaminations for a series of EPed niobium samples located at various positions of a single cell niobium cavity followed by ultrapure water rinsing as well as our endeavor to understand the aging effect of EP acid solution in terms of contaminations presence at the inner surface of the cavity with the help of surface analytical tools such as XPS, SIMS, and scanning electron microscope at KEK.

  9. Superconducting radio-frequency cavities made from medium and low-purity niobium ingots

    Science.gov (United States)

    Ciovati, Gianluigi; Dhakal, Pashupati; Myneni, Ganapati R.

    2016-06-01

    Superconducting radio-frequency cavities made of ingot niobium with residual resistivity ratio (RRR) greater than 250 have proven to have similar or better performance than fine-grain Nb cavities of the same purity, after standard processing. The high purity requirement contributes to the high cost of the material. As superconducting accelerators operating in continuous-wave typically require cavities to operate at moderate accelerating gradients, using lower purity material could be advantageous not only to reduce cost but also to achieve higher Q 0-values. In this contribution we present the results from cryogenic RF tests of 1.3–1.5 GHz single-cell cavities made of ingot Nb of medium (RRR = 100–150) and low (RRR = 60) purity from different suppliers. Cavities made of medium-purity ingots routinely achieved peak surface magnetic field values greater than 70 mT with an average Q 0-value of 2 × 1010 at 2 K after standard processing treatments. The performances of cavities made of low-purity ingots were affected by significant pitting of the surface after chemical etching.

  10. Tunable KTA Stokes laser based on stimulated polariton scattering and its intracavity frequency doubling.

    Science.gov (United States)

    Zang, Jie; Cong, Zhenhua; Chen, Xiaohan; Zhang, Xingyu; Qin, Zengguang; Liu, Zhaojun; Lu, Jianren; Wu, Dong; Fu, Qiang; Jiang, Shiqi; Zhang, Shaojun

    2016-04-01

    This paper presents the tunable Stokes laser characteristics of KTiOAsO4 (KTA) crystal based on stimulated polariton scattering (SPS). When the pumping laser wavelength is 1064.2 nm, the KTA Stokes wave can be discontinuously tuned from 1077.9 to 1088.4 nm with four gaps from 1079.0 to 1080.1 nm, from 1080.8 to 1082.8 nm, from 1083.6 to 1085.5 nm, and from 1085.8 to 1086.8 nm. When a frequency doubling crystal LiB3O5 (LBO) is inserted into the Stokes laser cavity, the frequency-doubled wave can be discontinuously tuned from 539.0 to 539.5 nm, from 540.1 to 540.4 nm, from 541.3 to 541.8 nm, from 542.7 to 542.9 nm and from 543.4 to 544.2 nm. With a pumping pulse energy of 130.0 mJ and an output coupler reflectivity of about 30%, the obtained maximum Stokes laser pulse energy at 1078.6 nm is 33.9 mJ and the obtained maximum frequency-doubled laser pulse energy at 543.8 nm is 15.7 mJ. By using the most probably coupled transverse optical modes obtained from the literature, the polariton refractive indexes, and the simplified polariton Sellmeier equations, the polariton dispersion curve is obtained. The formation of the Stokes frequency gaps is explained. PMID:27137044

  11. A phase mixing model for the frequency-doubling illusion.

    Science.gov (United States)

    Wielaard, James; Smith, R Theodore

    2013-10-01

    We introduce a temporal phase mixing model for a description of the frequency-doubling illusion (FDI). The model is generic in the sense that it can be set to refer to retinal ganglion cells, lateral geniculate cells, as well as simple cells in the primary visual cortex (V1). Model parameters, however, strongly suggest that the FDI originates in the cortex. The model shows how noise in the response phases of cells in V1, or in further processing of these phases, easily produces observed behavior of FDI onset as a function of spatiotemporal frequencies. It also shows how this noise can accommodate physiologically plausible spatial delays in comparing neural signals over a distance. The model offers an explanation for the disappearance of the FDI at sufficiently high spatial frequencies via increasingly correlated coding of neighboring grating stripes. Further, when the FDI is equated to vanishing perceptual discrimination between asynchronous contrast-reversal gratings, the model proposes the possibility that the FDI shows a resonance behavior at sufficiently high spatial frequencies, by which it is alternately perceived and not perceived in sequential temporal frequency bands.

  12. 双程腔内倍频激光器的谐波晶体腔内位置的理论研究%The Theory Research on the Location of a Frequency Doubling Crystal in a Double-pass Intracavity Frequency Doubling Laser

    Institute of Scientific and Technical Information of China (English)

    程一斌

    2000-01-01

    In this paper, the location of a frequency doubling crystal in a double-pass intra cavity frequency doubling and plano- concave confignration' s laser whose output was inone direc tion was analyzed in theory, and the formula of the suitable space between the frequency doubling crystal and the fiat mirror was obtained.%从理论上分析了平-凹腔结构的双程谐波、单方向输出的腔内谐波激光器的谐 波晶体腔内位置的选择,获得了谐波晶体与全反射镜的合理间距的解析式。

  13. Controlling double-cavity optical switching in a K-type multilevel system including spontaneously generated coherence

    Energy Technology Data Exchange (ETDEWEB)

    Osman, K.I., E-mail: kie_osman@hotmail.com [Department of Mathematics, Al-Azhar University, Faculty of Science (Women' s Section), P.O. Box 11754, Nasr City, Cairo (Egypt); Joshi, A., E-mail: ajoshi@eiu.edu [Department of Physics, Eastern Illinois University, Charleston, IL 61920 (United States)

    2012-07-30

    A composite system consisting of a K-type atomic medium and a double optical cavity configuration is considered to study the phenomenon of atomic optical bistability (AOB) in the mean field approximation. The controllability of this phenomenon achieved by additional electromagnetic fields not circulating in the cavities is studied. Also, the effect of spontaneously generated coherence due to the quantum interference in decaying nearby levels on the multi-branched AOB is discussed. The system displays a new class of bifurcations. -- Highlights: ► Optical bistability (OB) in a K-type atomic medium inside a double optical cavity. ► Controllability of OB via electromagnetic fields not circulating in the cavities. ► Controllability of OB via spontaneously generated coherence due to decaying levels. ► The system displays a new class of bifurcations.

  14. 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

  15. Self-consistent modeling of terahertz waveguide and cavity with frequency-dependent conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y. J.; Chu, K. R., E-mail: krchu@yahoo.com.tw [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Thumm, M. [IHM and IHE, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2015-01-15

    The surface resistance of metals, and hence the Ohmic dissipation per unit area, scales with the square root of the frequency of an incident electromagnetic wave. As is well recognized, this can lead to excessive wall losses at terahertz (THz) frequencies. On the other hand, high-frequency oscillatory motion of conduction electrons tends to mitigate the collisional damping. As a result, the classical theory predicts that metals behave more like a transparent medium at frequencies above the ultraviolet. Such a behavior difference is inherent in the AC conductivity, a frequency-dependent complex quantity commonly used to treat electromagnetics of metals at optical frequencies. The THz region falls in the gap between microwave and optical frequencies. However, metals are still commonly modeled by the DC conductivity in currently active vacuum electronics research aimed at the development of high-power THz sources (notably the gyrotron), although a small reduction of the DC conductivity due to surface roughness is sometimes included. In this study, we present a self-consistent modeling of the gyrotron interaction structures (a metallic waveguide or cavity) with the AC conductivity. The resulting waveguide attenuation constants and cavity quality factors are compared with those of the DC-conductivity model. The reduction in Ohmic losses under the AC-conductivity model is shown to be increasingly significant as the frequency reaches deeper into the THz region. Such effects are of considerable importance to THz gyrotrons for which the minimization of Ohmic losses constitutes a major design consideration.

  16. Electromagnetic Response of High-Frequency Gravitational Waves by Coupling Open Resonant Cavity

    Institute of Scientific and Technical Information of China (English)

    LI Fang-Yu; CHEN Ying; WANG Ping

    2007-01-01

    We present a new detecting scheme of high-frequency gravitational waves(HFGWs) in the GHz band,the scheme consists of a high-quality-factor open microwave cavity,a static magnetic field passing through the cavity and an electromagnetic (EM)normal mode stored in the cavity.It is found that under the resonant condition firstand second-order perturbation EM effects have almost the same detecting sensitivity to the HFGWs in the GHz band (h~10-26,v~5GHz),but the former contains more information from the HFGWs.We akso provide a very brief review for possible improving way of the sensitivity.This scheme would be Highly complementary to other schemes of detecting the HFGWs.

  17. Strong Meissner screening change in superconducting radio frequency cavities due to mild baking

    Energy Technology Data Exchange (ETDEWEB)

    Romanenko, A., E-mail: aroman@fnal.gov; Grassellino, A.; Barkov, F. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Suter, A.; Salman, Z.; Prokscha, T. [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-02-17

    We investigate “hot” regions with anomalous high field dissipation in bulk niobium superconducting radio frequency cavities for particle accelerators by using low energy muon spin rotation (LE-μSR) on corresponding cavity cutouts. We demonstrate that superconducting properties at the hot region are well described by the non-local Pippard/BCS model for niobium in the clean limit with a London penetration depth λ{sub L}=23±2 nm. In contrast, a cutout sample from the 120 ∘C baked cavity shows a much larger λ>100 nm and a depth dependent mean free path, likely due to gradient in vacancy concentration. We suggest that these vacancies can efficiently trap hydrogen and hence prevent the formation of hydrides responsible for rf losses in hot regions.

  18. Double layers and plasma-wave resistivity in extragalactic jets: Cavity formation and radio-wave emission

    Science.gov (United States)

    Borovsky, Joseph E.

    1987-01-01

    For estimated values of the currents carried by extragalactic jets, current-driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur. Strong plasma double layers, however, may exist within self-maintained density cavities, the relativistic double-layer-emitted electron, and ion beams driving plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  19. Double layers and plasma-wave resistivity in extragalactic jets - Cavity formation and radio-wave emission

    Science.gov (United States)

    Borovsky, Joseph E.

    1987-01-01

    Current driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur in extragalactic jets for estimated values of the carried currents. Strong plasma double layers, however, may exist within self-maintained density cavities. The relativistic double-layer-emitted electron and ion beams drive plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  20. Studies of radiation fields of LCLS-II super conducting radio frequency cavities

    Science.gov (United States)

    Santana Leitner, M.; Ge, L.; Li, Z.; Xu, C.; Adolphsen, C.; Ross, M.; Carrasco, M.

    2016-09-01

    The Linac Coherent Light Source II (LCLS-II) will be a hard X-ray Free Electron Laser whose linac can deliver a 1.2 MW CW electron beam with bunch rates up to 1 MHz. To efficiently generate such a high power beam, Super-Conducting Radio-Frequency (SCRF) cavities will be installed in the upstream portion of the existing 3 km Linac at the SLAC National Accelerator Laboratory. The 9-cell niobium cavities will be cooled at 2K inside 35 cryomodules, each containing a string of eight of those cavities followed by a quadrupole. The strong electromagnetic fields in the SCRF cavities will extract electrons from the cavity walls that may be accelerated. Most such dark current will be deposited locally, although some electrons may reach several neighboring cryomodules, gaining substantial energy before they hit a collimator or other aperture. The power deposited by the field emitted electrons and the associated showers may pose radiation and machine protection issues at the cryomodules and also in other areas of the accelerator. Simulation of these effects is therefore crucial for the design of the machine. The in-house code Track3P was used to simulate field emitted electrons from the LCLS-II cavities, and a sophisticated 3D model of the cryomodules including all cavities was written to transport radiation with the Fluka Monte Carlo code, which was linked to Track3P through custom-made routines. This setup was used to compute power deposition in components, prompt and residual radiation fields, and radioisotope inventories.

  1. Green pulsed lidar-radar emitter based on a multipass frequency-shifting external cavity.

    Science.gov (United States)

    Zhang, Haiyang; Brunel, Marc; Romanelli, Marco; Vallet, Marc

    2016-04-01

    This paper investigates the radio frequency (RF) up-conversion properties of a frequency-shifting external cavity on a laser beam. We consider an infrared passively Q-switched pulsed laser whose intensity modulation results from the multiple round-trips in the external cavity, which contains a frequency shifter. The output beam undergoes optical second-harmonic generation necessary to reach the green wavelength. We model the pulse train using a rate-equation model to simulate the laser pulses, together with a time-delayed interference calculation taking both the diffraction efficiency and the Gaussian beam propagation into account. The predictions are verified experimentally using a diode-pumped Nd:YAG laser passively Q-switched by Cr4+:YAG whose pulse train makes multiple round-trips in a mode-matched external cavity containing an acousto-optic frequency shifter driven at 85 MHz. Second-harmonic generation is realized in a KTP crystal, yielding RF-modulated pulses at 532 nm with a modulation contrast of almost 100%. RF harmonics up to the 6th order (1.020 GHz) are observed in the green output pulses. Such a RF-modulated green laser may find applications in underwater detection and ranging. PMID:27139644

  2. Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna

    Science.gov (United States)

    Wu, Te-Kao (Inventor)

    1994-01-01

    A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.

  3. High-mechanical-frequency characteristics of optomechanical crystal cavity with coupling waveguide

    Science.gov (United States)

    Huang, Zhilei; Cui, Kaiyu; Bai, Guoren; Feng, Xue; Liu, Fang; Zhang, Wei; Huang, Yidong

    2016-01-01

    Optomechanical crystals have attracted great attention recently for their ability to realize strong photon-phonon interaction in cavity optomechanical systems. By far, the operation of cavity optomechanical systems with high mechanical frequency has to employ tapered fibres or one-sided waveguides with circulators to couple the light into and out of the cavities, which hinders their on-chip applications. Here, we demonstrate larger-centre-hole nanobeam structures with on-chip transmission-coupling waveguide. The measured mechanical frequency is up to 4.47 GHz, with a high mechanical Q-factor of 1.4 × 103 in the ambient environment. The corresponding optomechanical coupling rate is calculated and measured to be 836 kHz and 1.2 MHz, respectively, while the effective mass is estimated to be 136 fg. With the transmission waveguide coupled structure and a small footprint of 3.4 μm2, this simple cavity can be directly used as functional components or integrated with other on-chip devices in future practical applications. PMID:27686419

  4. 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, $\

  5. Laser Frequency Stabilization and Control through Offset Sideband Locking to Optical Cavities

    Science.gov (United States)

    Thorpe, James I.; Livas, J.; Numata, K.

    2008-01-01

    We describe a class of techniques whereby a laser frequency can be stabilized to a fixed optical cavity resonance with an adjustable offset, providing a wide tuning range for the central frequency. These techniques require only minor modifications to the standard Pound-Drever-Hall locking techniques and have the advantage of not altering the intrinsic stability of the frequency reference. In a laboratory investigation the sideband techniques were found to perform equally well as the standard, non-tunable Pound-Drever-Hall technique, each providing more than four decades of frequency noise suppression over the free-running noise. An application of a tunable system as a pre-stabilization stage in a phase-lock loop is also presented with the combined system achieving a frequency noise suppression of nearly twelve orders of magnitude.

  6. A double-frequency rf gun for field emission

    International Nuclear Information System (INIS)

    Cold cathodes have attracted a lot of attention in the field of accelerators in recent years. While the development of suitable cold cathodes is in progress, attempts have been made to combine the cold cathode with a rf structure. Due to the strong dependence on the electric field, field emissions peak at the wave crest, which is not the best injection phase, during a rf cycle. To make the injection phase adjustable, a flexible double-frequency rf gun is designed. The addition of a 3rd-harmonic field to the fundamental one in the half cell will move the wave crest toward a better injection phase and make the initial bunch length shorter. The full cell is resonant at the fundamental frequency. Since only the half cell is resonant at two frequencies, the gun can be easily tuned. Simulations show that the time-dependent rf effects on the transverse and longitudinal phase spaces of the electron bunch can be reduced by choosing proper rf parameters and the space charge effects can be compensated for by using an external solenoid field. Therefore, the gun is able to provide low emittance, low energy spread and short electron bunches with high average current

  7. Parametric generation of radiation in a dynamic cavity with frequency dispersion

    Science.gov (United States)

    Rosanov, N. N.; Fedorov, E. G.; Matskovsky, A. A.

    2016-01-01

    A numerical simulation of the parametric generation of electromagnetic radiation in a cavity with periodically oscillating mirrors and Lorentz-type frequency dispersion has been performed. It is shown that initially weak seed radiation can be transformed into intense short pulses, the shape of which under steady-state conditions changes periodically when reflecting from mirrors and, depending on the dispersion characteristics, corresponds to uni- or bipolar pulses.

  8. Broadband Kerr frequency combs and intracavity soliton dynamics influenced by high-order cavity dispersion

    DEFF Research Database (Denmark)

    Wang, Shaofei; Guo, Hairun; Bai, Xuekun;

    2014-01-01

    , showing that temporal shifts of steady-state intracavity solitons are induced by high-odd-order dispersion rather than high-even-order dispersion. The role of HOD on comb spectral envelopes is also elucidated through analyzing the intracavity dispersive wave generations. We further demonstrate...... that the spectral envelope of a broadband optical frequency comb can be engineered by using a cavity dispersion profile with multiple zero dispersion wavelengths. © 2014 Optical Society of America....

  9. Dither Cavity Length Controller with Iodine Locking

    Directory of Open Access Journals (Sweden)

    Lawson Marty

    2016-01-01

    Full Text Available A cavity length controller for a seeded Q-switched frequency doubled Nd:YAG laser is constructed. The cavity length controller uses a piezo-mirror dither voltage to find the optimum length for the seeded cavity. The piezo-mirror dither also dithers the optical frequency of the output pulse. [1]. This dither in optical frequency is then used to lock to an Iodine absorption line.

  10. Squeezing via coupling of Bose–Einstein condensates in a double-well potential with a cavity light field

    International Nuclear Information System (INIS)

    Squeezing via the interaction between the cavity light field and the Bose–Einstein Condensate (BEC) in a double-well potential is considered within the context of the two-mode approximation. For the cavity light field initially in a coherent state, it is shown that by choosing appropriate parameters, quadrature squeezing of the cavity light field can be achieved and it exhibits periodic oscillation. We also study the case in which BEC is tuned to resonance by periodically modulating the trapping potential, and the quadrature squeezing of the cavity field exhibits periodic collapse and revival effect. Both analytic and numerical calculations are performed, and they are found to be in good agreement with each other. The result shows that the quantum statistical properties of the cavity light field can be manipulated by its coupling with the condensates in the double-well potential. On the other hand, dynamical properties of the condensates in the double-well potential will be reflected by the quadrature squeezing of the light field

  11. Frequency stabilization in FBG external cavity semiconductor laser based on acetylene absorption method

    Institute of Scientific and Technical Information of China (English)

    Li Zhi-quan; Su Feng-yan; Kang Li-li

    2008-01-01

    A frequency-stabilized 1.53 μm FBG external-cavity semiconductor laser by using acetylene absorption is presented and its basic principles are introduced. Graded refractive index fiber and pigtailed fiber are used in the absorption air chamber to enhance the coupling stability. The impact of the background power is eliminated by using the third-harmonic modelocking technique. A lock-in amplifier is utilized to ensure that the output laser wavelength is locked at the C2H2 absorption line of 1530.37 nm. The frequency stability reaches 10-8 within 24 h.

  12. Single-frequency blue light generation by single-pass sum-frequency generation in a coupled ring cavity tapered laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Petersen, Paul Michael

    2013-01-01

    A generic approach for generation of tunable single frequency light is presented. 340 mW of near diffraction limited, single-frequency, and tunable blue light around 459 nm is generated by sum-frequency generation (SFG) between two tunable tapered diode lasers. One diode laser is operated in a ring...... cavity and another tapered diode laser is single-passed through a nonlinear crystal which is contained in the coupled ring cavity. Using this method, the single-pass conversion efficiency is more than 25%. In contrast to SFG in an external cavity, the system is entirely self-stabilized with no electronic...

  13. High finesse external cavity VCSELs: from very low noise lasers to dual frequency lasers

    Science.gov (United States)

    Baili, Ghaya; Alouini, Medhi; Morvan, Loic; Bretenaker, Fabien; Sagnes, Isabelle; Garnache, Arnaud; Dolfi, Daniel

    2011-01-01

    Low noise-level optical sources are required for numerous applications such as microwave photonics, fiber-optic sensing and time/frequency references distribution. In this paper, we demonstrate how inserting a SC active medium into a centimetric high-Q external cavity is a simple way to obtain a shot-noise-limited laser source over a very wide frequency bandwidth. This approach ensures, with a compact design, a sufficiently long photon lifetime to reach the oscillation-relaxation- free class-A regime. This concept has been illustrated by inserting a 1/2-VCSEL in an external cavity including an etalon filter. A -156dB/Hz relative intensity noise level is obtained over the 100 MHz to 18 GHz bandwidth of interest. This is several orders of magnitude better than the noise, previously observed in VCSELs, belonging to the class-B regime. The optimization, in terms of noise, is shown to be a trade-off between the cavity length and the laser mode filtering. The transition between the class-B and class-A dynamical behaviors is directly observed by continuously controlling the photon lifetime is a sub-millimetric to a centimetric cavity length. It's proven that the transition occurs progressively, without any discontinuity. Based on the same laser architecture, tunable dual-frequency oscillation is demonstrated by reducing the polarized eigenstates overlap in the gain medium. The class-A dynamics of such a laser, free of relaxation oscillations, enables to suppress the electrical phase noise in excess, usually observed in the vicinity of the beat note. An original technique for jitter reduction in mode-locked VECSELs is also investigated. Such lasers are needed for photonic analog to digital converters.

  14. First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

    2013-09-01

    Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

  15. Frequency and time domain analysis of an external cavity laser with strong filtered optical feedback

    DEFF Research Database (Denmark)

    Detoma, Enrico; Tromborg, Bjarne; Montrosset, Ivo

    The stability properties of an external cavity laser with strong grating-filtered optical feedback to an anti-reflection coated facet are studied with a general frequency domain model. The model takes into account non-linear effects like four wave mixing and gain compression. A small-signal analy...... copression in the lasing mode. An integral equation for the electrical field is derived from the frequency domain model and used for time domain simulations of large-signal behavior.......The stability properties of an external cavity laser with strong grating-filtered optical feedback to an anti-reflection coated facet are studied with a general frequency domain model. The model takes into account non-linear effects like four wave mixing and gain compression. A small......-signal analysis in the frequency domain allows a calculation of the range of operation without mode hopping around the grating reflectivity peak. This region should be as large as possible for proper operation of the tunable laser source. The analysis shows this stabilizing effect of mode coupling and gain...

  16. Application of superconducting magnesium diboride (MGB2) in superconducting radio frequency cavities

    Science.gov (United States)

    Tan, Teng

    The superconductivity in magnesium diboride (MgB2) was discovered in 2001. As a BCS superconductor, MgB2 has a record-high Tc of 39 K, high Jc of > 107 A/cm2 and no weak link behavior across the grain boundary. All these superior properties endorsed that MgB2 would have great potential in both power applications and electronic devices. In the past 15 years, MgB2 based power cables, microwave devices, and commercial MRI machines emerged and the next frontier are superconducting radio frequency (SRF) cavities. SRF cavities are one of the leading accelerator technologies. In SRF cavities, applied microwave power generates electrical fields that accelerate particle beams. Compared with other accelerator techniques, SRF cavity accelerators feature low loss, high acceleration gradients and the ability to accelerate continuous particle beams. However, current SRF cavities are made from high-purity bulk niobium and work at 2 K in superfluid helium. The construction and operational cost of SRF cavity accelerators are very expensive. The demand for SRF cavity accelerators has been growing rapidly in the past decade. Therefore, a lot of effort has been devoted to the enhancement of the performance and the reduction of cost of SRF cavities. In 2010, an acceleration gradient of over 50 MV/m has been reported for a Nb-based SRF cavity. The magnetic field at the inner surface of such a cavity is ~ 1700 Oe, which is close to the thermodynamic critical field of Nb. Therefore, new materials and technologies are required to raise the acceleration gradient of future SRF cavity accelerators. Among all the proposed approaches, using MgB2 thin films to coat the inner surface of SRF cavities is one of the promising tactics with the potential to raise both the acceleration gradient and the operation temperature of SRF cavity accelerators. In this work, I present my study on MgB2 thin films for their application in SRF cavities. C-epitaxial MgB2 thin films grown on SiC(0001) substrates

  17. High-power single- and double-frequency, tunable mini-laser with nano-film selector for onboard applications

    Science.gov (United States)

    Peshko, Igor; Rubtsov, Vladimir; Jabczynski, Jan; Kopczynski, Krzysztof

    2006-05-01

    A new architecture of single-frequency high efficiency mini-solid-state lasers is proposed. The application of a metallic nano-film selector has been investigated theoretically and experimentally. It has been shown that a cobalt thinfilm selector with a thickness between 8 and 10 nm provides a single- frequency output within a power range of up to 0.6 W with a 1-mm thick Nd:YVO 4 gain crystal. At single-mode operation, it accumulated 85% of the multimode laser output. Slope efficiencies of single-frequency oscillation from 41% to 53% have been demonstrated for different crystals. The output coupler movement by piezoceramic transducer provided single-frequency operation, with slow smooth tuning, or chirping. The laser, with a cavity length less than 1", provided smooth tuning up to 10 GHz, frequency chirping up to 4 GHz with a repetition rate of about 0.5 kHz, and hop tuning over 150 GHz at a maximum pump power of 1.8 W. Double-frequency operation with a separation of 1.5 to 2.5 GHz was realized in a laser with a cavity length up to 100 mm. Physical and technical limitations caused by the wide-gain bandwidth, thermal effects, and mechanical vibrations of the cavity elements are discussed. The new specific regime of frequency self-stabilization provided with a thin-film metallic selector has been proposed. Slow, periodical self-modulation phenomena in the diode-pumped singlefrequency Nd:YVO 4 laser with a cobalt thin-film selector have been demonstrated. Pulses with duration of about l to 3s and periods of about 3 to 10 s have been observed.

  18. Optical feedback characteristics in a dual-frequency laser during laser cavity tuning

    Institute of Scientific and Technical Information of China (English)

    Liu Gang; Zhang Shu-Lian; Li Yan; Zhu Jun

    2005-01-01

    The optical feedback characteristics in a Zeeman-birefringence dual-frequency laser are studied during the laser cavity tuning in three different kinds of optical feedback conditions: (i) only //-light is fed back; (ii) only (┴)-light is fed back; (iii) both lights are fed back. A compact displacement sensor is designed using the experimental result that there is a nearly 90 degrees phase delay between the two lights' cosine optical feedback signals when both lights are fed back into the laser cavity. The priority order that the two lights' intensity curves appear can be used for direction discrimination. The resolution of the displacement sensor is at least 79 nm, and the sensor can discriminate the target's moving direction easily.

  19. Effective index model predicts modal frequencies of vertical-cavity lasers

    Energy Technology Data Exchange (ETDEWEB)

    SERKLAND,DARWIN K.; HADLEY,G. RONALD; CHOQUETTE,KENT D.; GEIB,KENT M.; ALLERMAN,ANDREW A.

    2000-04-18

    Previously, an effective index optical model was introduced for the analysis of lateral waveguiding effects in vertical-cavity surface-emitting lasers. The authors show that the resultant transverse equation is almost identical to the one typically obtained in the analysis of dielectric waveguide problems, such as a step-index optical fiber. The solution to the transverse equation yields the lateral dependence of the optical field and, as is recognized in this paper, the discrete frequencies of the microcavity modes. As an example, they apply this technique to the analysis of vertical-cavity lasers that contain thin-oxide apertures. The model intuitively explains the experimental data and makes quantitative predictions in good agreement with a highly accurate numerical model.

  20. Multi-cavity coupling acoustic metamaterials with low-frequency broad band gaps based on negative mass density

    Science.gov (United States)

    Yang, Chuanhui; Wu, Jiu Hui; Cao, Songhua; Jing, Li

    2016-08-01

    This paper studies a novel kind of low-frequency broadband acoustic metamaterials with small size based on the mechanisms of negative mass density and multi-cavity coupling. The structure consists of a closed resonant cavity and an open resonant cavity, which can be equivalent to a homogeneous medium with effective negative mass density in a certain frequency range by using the parameter inversion method. The negative mass density makes the anti-resonance area increased, which results in broadened band gaps greatly. Owing to the multi-cavity coupling mechanism, the local resonances of the lower frequency mainly occur in the closed cavity, while the local resonances of the higher frequency mainly in the open cavity. Upon the interaction between the negative mass density and the multi-cavity coupling, there exists two broad band gaps in the range of 0-1800 Hz, i.e. the first-order band gap from 195 Hz to 660 Hz with the bandwidth of 465 Hz and the second-order band gap from 1157 Hz to 1663 Hz with the bandwidth of 506 Hz. The acoustic metamaterials with small size presented in this paper could provide a new approach to reduce the low-frequency broadband noises.

  1. A frequency-locked and frequency-doubled, hybrid Q-switched Yb:KYW laser at 515 nm with a widely adjustable repetition rate

    Science.gov (United States)

    Tjörnhammar, S.; Zukauskas, A.; Canalias, C.; Pasiskevicius, V.; Laurell, F.

    2015-09-01

    We demonstrate a compact wavelength-stabilized, frequency-doubled Yb-doped double-tungstate laser with widely tunable repetition rate, spanning from 35 Hz to 3 kHz obtained by hybrid Q-switching. The Q-switching unit consisted of a combination of a passive Cr:YAG crystal and an opto-mechanical active intensity modulator. The fundamental wavelength was locked at 1029 nm with a volume Bragg grating, and the pulse length and energy were 42 ns and 250 µJ, respectively. As the laser was stabilized with the VBG and the opto-mechanical modulator, the frequency instability was reduced six times from free running down to 0.29 %. Frequency doubling was done extra-cavity in PPKTP, and a repetition rate-independent conversion efficiency of 63 % was obtained. The controllable repetition rate together with stable temporal and spatial characteristics makes this laser a suitable candidate in many biology-related experiments, as a pump source for in vivo excitation of fluorophores, e.g., pumping of "living lasers" and matrix-assisted laser desorption/ionization mass spectroscopy.

  2. Onset of Double-Diffusive Convection in a Rectangular Cavity and Its Generation Mechanism

    Science.gov (United States)

    Mizushima, Jiro; Yasumizu, Yuto; Ohashi, Shunsuke

    2013-08-01

    Two-dimensional double diffusive convection in a binary fluid mixture filled in a container with a rectangular cross section is investigated by linear stability analyses, numerical simulations and numerical calculations of steady solutions in the present paper. We mainly consider an ethanol--water mixture as the binary fluid, in which heat and ethanol diffuse in different time scales affecting the fluid motion through buoyancy force and the Soret effect. The bottom of the cavity is kept at a higher temperature than the top, and the side boundary walls are assumed to be perfectly insulating. The impermeability condition of mass is applied on all the boundaries. We obtain the critical condition for the onset of double diffusive convection, and examine the flow field at the criticality. It is found that the most unstable mode of disturbance is oscillatory at the criticality for negative values of the separation number, though it is a steady mode of disturbance for positive or null values of the separation number. We discuss the driving mechanism of the steady and oscillatory convections by evaluating torques exerted on the fluid due to the buoyancy force, the pressure and the viscosity separately in each. We find in numerical simulations that the convection, even if it is oscillatory initially, always attains a steady state in due course in the case of a container with a square cross section. The bifurcation diagram of the steady convection is obtained numerically and the relation between the steady convection and the oscillatory mode of disturbance arising due to the linear instability is briefly discussed.

  3. An innovative MRE absorber with double natural frequencies for wide frequency bandwidth vibration absorption

    Science.gov (United States)

    Sun, Shuaishuai; Yang, Jian; Li, Weihua; Deng, Huaxia; Du, Haiping; Alici, Gursel; Yan, Tianhong

    2016-05-01

    A new design of adaptive tuned vibration absorber was proposed in this study for vibration reduction. The innovation of the new absorber is the adoption of the eccentric mass on the top of the multilayered magnetorheological elastomer (MRE) structure so that this proposed absorber has two vibration modes: one in the torsional direction and the other in translational direction. This property enables the absorber to expand its effective bandwidth and to be more capable of reducing the vibrations especially dealing with those vibrations with multi-frequencies. The innovative MRE absorber was designed and tested on a horizontal vibration table. The test results illustrate that the MRE absorber realized double natural frequencies, both of which are controllable. Inertia’s influence on the dynamic behavior of the absorber is also investigated in order to guide the design of the innovative MRE absorber. Additionally, the experimentally obtained natural frequencies coincide with the theoretical data, which sufficiently verifies the feasibility of this new design. The last part in terms of the vibration absorption ability also proves that both of these two natural frequencies play a great role in absorbing vibration energy.

  4. Theory analysis and experiment investigations of an original double-gap cavity%一种新型双间隙输出腔的理论和实验研究

    Institute of Scientific and Technical Information of China (English)

    崔学芳; 刘庆想; 李旭东; 范植开

    2001-01-01

    Starting from the cold dispersion relation, which is employed to numerically calculate eigenfrequencies for the double-gap split cavity, thereby the resonant frequency for the split cavity TM010 mode are obtained and the distributing character of π-mode are discussed. Accordingly, the split cavity can be used as double-gap output cavity. And then the double-gap output cavity is designed by using the 2.5D, relativistic, fully electromagnetic, PIC code KARAT, and more optimizing the construct of output cavity. At last by modulating the different construct parameters, the cold tests are carried on, and by which the low-QL output cavity of center frequency 3.74GHz and 7.8 of load QL is developed.%从双间隙分离腔的色散关系式出发,通过数值计算求出了分离腔中TM010模对应的谐振频率,并给出了腔内轴向电场的分布图,证实了分离腔中存在着电场反相的π模场。因此,可以将其用作电场反相的双间隙输出腔,来实现双间隙提取。并用2.5维粒子模拟程序卡拉特(KARAT)程序对这种分离腔输出回路进行了粒子模拟和优化设计。通过详细的冷测和调试实验,研制出了中心频率为3.74GHz,QL值为7.8的低QL值双间隙输出腔。

  5. A novel approach to characterizing the surface topography of niobium superconducting radio frequency (SRF) accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Tian Hui [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Applied Sci. Dept., College of William and Mary, Williamsburg, VA 23185 (United States); Ribeill, Guilhem [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Dept. of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Xu Chen [Applied Sci. Dept., College of William and Mary, Williamsburg, VA 23185 (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Kelley, Michael J., E-mail: mkelley@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Applied Sci. Dept., College of William and Mary, Williamsburg, VA 23185 (United States)

    2011-03-15

    As superconducting niobium radio-frequency (SRF) cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on realized performance limitations. Micro- and nano-roughness are implicated in both direct geometrical field enhancements as well as complications of the composition of the 50 nm surface layer in which the super-currents typically flow. Interior surface chemical treatments such as buffered chemical polishing (BCP) and electropolishing (EP) used to remove mechanical damage leave surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is introduced to distinguish the scale-dependent smoothing effects, resulting in a novel qualitative and quantitative description of Nb surface topography. The topographical evolution of the Nb surface as a function of different steps of well-controlled EP is discussed. This study will greatly help to identify optimum EP parameter sets for controlled and reproducible surface levelling of Nb for cavity production.

  6. A novel approach to characterizing the surface topography of niobium superconducting radio frequency (SRF) accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hui Tian, Guilhem Ribeill, Chen Xu, Charles E. Reece, Michael J. Kelley

    2011-03-01

    As superconducting niobium radio-frequency (SRF) cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on realized performance limitations. Micro- and nano-roughness are implicated in both direct geometrical field enhancements as well as complications of the composition of the 50 nm surface layer in which the super-currents typically flow. Interior surface chemical treatments such as buffered chemical polishing (BCP) and electropolishing (EP) used to remove mechanical damage leave surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is introduced to distinguish the scale-dependent smoothing effects, resulting in a novel qualitative and quantitative description of Nb surface topography. The topographical evolution of the Nb surface as a function of different steps of well-controlled EP is discussed. This study will greatly help to identify optimum EP parameter sets for controlled and reproducible surface levelling of Nb for cavity production.

  7. Study of Temperature Wave Propagation in Superfluid Helium Focusing on Radio-Frequency Cavity Cooling

    CERN Document Server

    Koettig, T; Avellino, S; Junginger, T; Bremer, J

    2015-01-01

    Oscillating Superleak Transducers (OSTs) can be used to localize quenches of superconducting radio-frequency cavities. Local hot spots at the cavity surface initiate temperature waves in the surrounding superfluid helium that acts as cooling fluid at typical temperatures in the range of 1.6 K to 2 K. The temperature wave is characterised by the properties of superfluid helium such as the second sound velocity. For high heat load densities second sound velocities greater than the standard literature values are observed. This fast propagation has been verified in dedicated small scale experiments. Resistors were used to simulate the quench spots under controlled conditions. The three dimensional propagation of second sound is linked to OST signals. The aim of this study is to improve the understanding of the OST signal especially the incident angle dependency. The characterised OSTs are used as a tool for quench localisation on a real size cavity. Their sensitivity as well as the time resolution was proven to b...

  8. Frequency tuning of polarization oscillations in spin-polarized vertical-cavity surface-emitting lasers

    Science.gov (United States)

    Lindemann, Markus; Pusch, Tobias; Michalzik, Rainer; Gerhardt, Nils C.; Hofmann, Martin R.

    2016-04-01

    Controlling the coupled spin-photon dynamics in vertical-cavity surface-emitting lasers (VCSELs) is an attractive opportunity to overcome the limitations of conventional, purely charge based semiconductor lasers. Such spin-controlled VCSELs (spin-VCSELs) offer several advantages, like reduced threshold, spin amplification and polarization control. Furthermore the coupling between carrier spin and light polarization bears the potential for ultrafast polarization dynamics. By injecting spin-polarized carriers, the complex polarization dynamics can be controlled and utilized for high-speed applications. Polarization oscillations as resonance oscillations of the coupled spin- photon system can be generated using pulsed spin injection, which can be much faster than the intensity dynamics in conventional devices. We already demonstrated that the oscillations can be switched in a controlled manner. These controllable polarization dynamics can be used for ultrafast polarization-based optical data communication. The polarization oscillation frequency and therefore the possible data transmission rate is assumed to be mainly determined by the birefringence-induced mode-splitting. This provides a direct tool to increase the polarization dynamics toward higher frequencies by adding a high amount of birefringence to the VCSEL structure. Using this technique, we could recently demonstrate experimentally a birefringence splitting of more than 250 GHz using mechanical strain. Here, we employ the well-known spin-flip model to investigate the tuning of the polarization oscillation frequency. The changing mechanical strain is represented by a linear birefringence sweep to values up to 80πGHz. The wide tuning range presented enables us to generate polarization oscillation frequencies exceeding the conventional intensity modulation frequency in the simulated device by far, mainly dependent on the birefringence in the cavity only.

  9. Low temperature laser scanning microscopy of a superconducting radio-frequency cavity.

    Science.gov (United States)

    Ciovati, G; Anlage, Steven M; Baldwin, C; Cheng, G; Flood, R; Jordan, K; Kneisel, P; Morrone, M; Nemes, G; Turlington, L; Wang, H; Wilson, K; Zhang, S

    2012-03-01

    An apparatus was developed to obtain, for the first time, 2D maps of the surface resistance of the inner surface of an operating superconducting radio-frequency niobium cavity by a low-temperature laser scanning microscopy technique. This allows identifying non-uniformities of the surface resistance with a spatial resolution of about 2.4 mm and surface resistance resolution of ~1 μΩ at 3.3 GHz. A signal-to-noise ratio of about 10 dB was obtained with 240 mW laser power and 1 Hz modulation frequency. The various components of the apparatus, the experimental procedure and results are discussed in detail in this contribution.

  10. Highly Accurate Frequency Calculations of Crab Cavities Using the VORPAL Computational Framework

    Energy Technology Data Exchange (ETDEWEB)

    Austin, T.M.; /Tech-X, Boulder; Cary, J.R.; /Tech-X, Boulder /Colorado U.; Bellantoni, L.; /Argonne

    2009-05-01

    We have applied the Werner-Cary method [J. Comp. Phys. 227, 5200-5214 (2008)] for extracting modes and mode frequencies from time-domain simulations of crab cavities, as are needed for the ILC and the beam delivery system of the LHC. This method for frequency extraction relies on a small number of simulations, and post-processing using the SVD algorithm with Tikhonov regularization. The time-domain simulations were carried out using the VORPAL computational framework, which is based on the eminently scalable finite-difference time-domain algorithm. A validation study was performed on an aluminum model of the 3.9 GHz RF separators built originally at Fermi National Accelerator Laboratory in the US. Comparisons with measurements of the A15 cavity show that this method can provide accuracy to within 0.01% of experimental results after accounting for manufacturing imperfections. To capture the near degeneracies two simulations, requiring in total a few hours on 600 processors were employed. This method has applications across many areas including obtaining MHD spectra from time-domain simulations.

  11. Tunable photonic cavity coupled to a voltage-biased double quantum dot system: Diagrammatic nonequilibrium Green's function approach

    Science.gov (United States)

    Agarwalla, Bijay Kumar; Kulkarni, Manas; Mukamel, Shaul; Segal, Dvira

    2016-07-01

    We investigate gain in microwave photonic cavities coupled to voltage-biased double quantum dot systems with an arbitrarily strong dot-lead coupling and with a Holstein-like light-matter interaction, by employing the diagrammatic Keldysh nonequilibrium Green's function approach. We compute out-of-equilibrium properties of the cavity: its transmission, phase response, mean photon number, power spectrum, and spectral function. We show that by the careful engineering of these hybrid light-matter systems, one can achieve a significant amplification of the optical signal with the voltage-biased electronic system serving as a gain medium. We also study the steady-state current across the device, identifying elastic and inelastic tunneling processes which involve the cavity mode. Our results show how recent advances in quantum electronics can be exploited to build hybrid light-matter systems that behave as microwave amplifiers and photon source devices. The diagrammatic Keldysh approach is primarily discussed for a cavity-coupled double quantum dot architecture, but it is generalizable to other hybrid light-matter systems.

  12. Thermal birefringence-compensated linear intracavity frequency doubled Nd:YAG rod laser with 73 ns pulse duration and 160Wgreen output power

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Gupta; P Hedaoo; P K Mukhopadhyay; K Ranganathan; K S Bindra; S M Oak

    2014-02-01

    In a thermally birefringence-compensated linear cavity configuration, ∼160 W of average green power by intracavity frequency doubling of AO Q-switched Nd:YAG/LBO-based laser is demonstrated. The corresponding optical to optical conversion efficiency is estimated to be ∼12.7%. The pulse repetition rate is 20 kHz with the individual pulse duration of 73 ns. The beam quality parameter is measured to be 18.

  13. Noise-immune cavity-enhanced optical frequency comb spectroscopy: A sensitive technique for high-resolution broadband molecular detection

    CERN Document Server

    Khodabakhsh, Amir; Foltynowicz, Aleksandra

    2014-01-01

    Noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS) is a recently developed technique that utilizes phase modulation to obtain immunity to frequency-to-amplitude noise conversion by the cavity modes and yields high absorption sensitivity over a broad spectral range. We describe the principles of the technique and discuss possible comb-cavity matching solutions. We present a theoretical description of NICE-OFCS signals detected with a Fourier transform spectrometer (FTS), and validate the model by comparing it to experimental CO2 spectra around 1575 nm. Our system is based on an Er:fiber femtosecond laser locked to a cavity and phase-modulated at a frequency equal to a multiple of the cavity free spectral range (FSR). The NICE-OFCS signal is detected by a fast-scanning FTS equipped with a high-bandwidth commercial detector. We demonstrate a simple method of passive locking of the modulation frequency to the cavity FSR that significantly improves the long term stability of the system, a...

  14. Towards strongly correlated photons in arrays of dissipative nonlinear cavities under a frequency-dependent incoherent pumping

    Science.gov (United States)

    Lebreuilly, José; Wouters, Michiel; Carusotto, Iacopo

    2016-10-01

    We report a theoretical study of a quantum optical model consisting of an array of strongly nonlinear cavities incoherently pumped by an ensemble of population-inverted two-level atoms. Projective methods are used to eliminate the atomic dynamics and write a generalized master equation for the photonic degrees of freedom only, where the frequency-dependence of gain introduces non-Markovian features. In the simplest single cavity configuration, this pumping scheme gives novel optical bistability effects and allows for the selective generation of Fock states with a well-defined photon number. For many cavities in a weakly non-Markovian limit, the non-equilibrium steady state recovers a Grand-Canonical statistical ensemble at a temperature determined by the effective atomic linewidth. For a two-cavity system in the strongly nonlinear regime, signatures of a Mott state with one photon per cavity are found. xml:lang="fr"

  15. 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.

  16. Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures

    OpenAIRE

    Grassellino, A.; Romanenko, A.; Melnychuk, O.; Trenikhina, Y.; Crawford, A; Rowe, A.; Wong, M; Sergatskov, D.; Khabiboulline, T.; Barkov, F.

    2013-01-01

    We report a surface treatment that systematically improves the quality factor of niobium radio frequency cavities beyond the expected limit for niobium. A combination of annealing in a partial pressure of nitrogen or argon gas and subsequent electropolishing of the niobium cavity surface leads to unprecedented low values of the microwave surface resistance, and an improvement in the efficiency of the accelerating structures up to a factor of 3, reducing the cryogenic load of superconducting c...

  17. Temporal characterization of FEL micropulses as function of cavity length detuning using frequency-resolved optical gating

    Energy Technology Data Exchange (ETDEWEB)

    Richman, B.A. [Stanford Univ., CA (United States); DeLong, K.W.; Trebino, R. [Sandia National Lab., Livermore, CA (United States)

    1995-12-31

    Results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL system show the effect of FEL cavity length detuning on the micropulse temporal structure. The FROG technique enables the acquisition of complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. The optical pulses are nearly transform limited, and the pulse length increases with cavity length detuning.

  18. Arm-length stabilisation for interferometric gravitational-wave detectors using frequency-doubled auxiliary lasers

    CERN Document Server

    Mullavey, Adam J; Miller, John; Evans, Matthew; Fritschel, Peter; Sigg, Daniel; Waldman, Sam J; Shaddock, Daniel A; McClelland, David E

    2011-01-01

    Residual motion of the arm cavity mirrors is expected to prove one of the principal impediments to systematic lock acquisition in advanced gravitational-wave interferometers. We present a technique which overcomes this problem by employing auxiliary lasers at twice the fundamental measurement frequency to pre-stabilise the arm cavities' lengths. Applying this approach, we reduce the apparent length noise of a 1.3 m long, independently suspended Fabry-Perot cavity to 30 pm rms and successfully transfer longitudinal control of the system from the auxiliary laser to the measurement laser.

  19. Temperature dependence of spontaneous switch-on and switch-off of laser cavity solitons in vertical-cavity surface-emitting lasers with frequency-selective feedback

    Science.gov (United States)

    Jimenez, J.; Oppo, G.-L.; Ackemann, T.

    2016-03-01

    A systematic experimental and numerical investigation of the conditions for the spontaneous formation of laser cavity solitons in broad-area vertical-cavity surface-emitting lasers with frequency-selective feedback by a volume Bragg grating is reported. It is shown that the switching thresholds are controlled by a combination of frequency shifts induced by ambient temperature and Joule heating. The gain level has only a minor influence on the threshold but controls mainly the power of the solitons. At large initial detuning and high threshold gain, the first observed structure can be a high order soliton. In real devices spatial disorder in the cavity length causes a pinning of solitons and a dispersion of thresholds. The experimental observations are in good agreement with numerical simulations taking into account disorder and the coupling of gain and cavity resonance due to Joule heating. In particular, we demonstrate that the existence of the traps explain the spontaneous switch on of the solitons, but do not modify the soliton shape significantly, i.e. the observed solitons are a good approximation of the ones expected in a homogeneous system.

  20. Temperature dependence of spontaneous switch-on and switch-off of laser cavity solitons in vertical-cavity surface-emitting lasers with frequency-selective feedback

    International Nuclear Information System (INIS)

    A systematic experimental and numerical investigation of the conditions for the spontaneous formation of laser cavity solitons in broad-area vertical-cavity surface-emitting lasers with frequency-selective feedback by a volume Bragg grating is reported. It is shown that the switching thresholds are controlled by a combination of frequency shifts induced by ambient temperature and Joule heating. The gain level has only a minor influence on the threshold but controls mainly the power of the solitons. At large initial detuning and high threshold gain, the first observed structure can be a high order soliton. In real devices spatial disorder in the cavity length causes a pinning of solitons and a dispersion of thresholds. The experimental observations are in good agreement with numerical simulations taking into account disorder and the coupling of gain and cavity resonance due to Joule heating. In particular, we demonstrate that the existence of the traps explain the spontaneous switch on of the solitons, but do not modify the soliton shape significantly, i.e. the observed solitons are a good approximation of the ones expected in a homogeneous system. (paper)

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

    OpenAIRE

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

    2012-01-01

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

  2. Development of PLC based control system for frequency tuning loop of 31.6 MHz RF cavity

    International Nuclear Information System (INIS)

    Two storage rings, Indus-1 and Indus-2 are operational at RRCAT. Both the storage rings share a common injector system consisting of a Microtron and a Booster Synchrotron. The electrons are generated and accelerated to 20 MeV in Microtron and injected through a transfer line into the Booster Synchrotron where its energy is increased to 450 MeV/550 MeV. In Booster Synchrotron, a MHz RF system is installed. This RF System includes 1 kW RF amplifier, re-entrant type RF cavity and its tuning system. The RF system works in ramp mode. In RF cavities, resonant frequency changes due to beam loading and temperature effect. Our aim is to keep the RF Cavity at fixed resonance. Frequency Tuning Loop (FTL) will keep the cavities tuned by compensating for both beam loading and temperature effects. This is realized by means of a mechanism, driven by a stepper motor, which changes the volume of RF cavity by moving the plunger in/out and therefore its frequency. A Programmable Logic Controller (PLC) based Control system was developed to replace existing control system for FTL of RF Cavity installed in Booster Synchrotron. The main components of the control system are the phase detector, PLC with analog module, optical isolation card and touch screen interface. Control logic was developed in Step-7 MicroWin. The complete control logic, advantages over the earlier control system and scope for adaptability has been thoroughly discussed in this paper

  3. Non-planar femtosecond enhancement cavity for VUV frequency comb applications

    CERN Document Server

    Winkler, Georg; Seres, Jozsef; Seres, Enikoe; Schumm, Thorsten

    2016-01-01

    External passive femtosecond enhancement cavities (fsECs) are widely used to increase the efficiency of non-linear conversion processes like high harmonic generation (HHG) at high repetition rates. Their performance is often limited by beam ellipticity, caused by oblique incidence on spherical focusing mirrors. We introduce a novel three-dimensionally folded variant of the typical planar bow-tie resonator geometry that guarantees circular beam profiles, maintains linear polarization, and allows for a significantly tighter focus as well as a larger beam cross-section on the cavity mirrors. The scheme is applied to improve focusing in a Ti:Sapphire based VUV frequency comb system, targeting the 5th harmonic around 160 nm (7.8 eV) towards high-precision spectroscopy of the low-energy isomer state of Thorium-229. It will also be beneficial in fsEC-applications with even higher seeding and intracavity power where the damage threshold of the mirrors becomes a major concern.

  4. Cavity partition and functionalization of a [2+3] organic molecular cage by inserting polar P[double bond, length as m-dash]O bonds.

    Science.gov (United States)

    Feng, Genfeng; Liu, Wei; Peng, Yuxin; Zhao, Bo; Huang, Wei; Dai, Yafei

    2016-07-28

    The cavity of a [2+3] organic molecular cage was partitioned and functionalized by inserting inner-directed P[double bond, length as m-dash]O bonds, which shows CO2 capture and CH4 exclusion due to the size-matching and polarity effects. Computational results demonstrate that the successful segmentation via polar P[double bond, length as m-dash]O bonds facilitates the CO2 molecules to reside selectively inside the cavity. PMID:27356151

  5. On geometrical scaling of split-ring and double-bar resonators at optical frequencies

    OpenAIRE

    Tretyakov, Sergei

    2006-01-01

    In this paper we consider the resonant frequency of split-ring resonators and double-bar resonators used to create artificial magnetic response at terahertz and optical frequencies. It is known that geometrical scaling of the resonant frequency of split rings breaks down at high frequencies (in the visible) due to electromagnetic properties of metals at those frequencies. Here we will discuss this phenomenon in terms of equivalent inductance and capacitance of the ring, derive an approximate ...

  6. Reclamation of niobium compounds from ionic liquid electrochemical polishing of superconducting radio frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Wixtrom, Alex I. [Christopher Newport University, Newport News, VA (United States); Buhler, Jessica E. [Christopher Newport University, Newport News, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Abdel-Fattah, Tarek M. [Christopher Newport University, Newport News, VA (United States)

    2013-06-01

    Recent research has shown that choline chloride (vitamin B4)-based solutions can be used as a greener alternative to acid-based electrochemical polishing solutions. This study demonstrated a successful method for electrochemical deposition of niobium compounds onto the surface of copper substrates using a novel choline chloride-based ionic liquid. Niobium ions present in the ionic liquid solution were dissolved into the solution prior to deposition via electrochemical polishing of solid niobium. A black coating was clearly visible on the surface of the Cu following deposition. This coating was analyzed using scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and X-ray fluorescence spectroscopy (XRF). This ionic liquid-based electrochemical deposition method effectively recycles previously dissolved niobium from electrochemical polishing of superconducting radio frequency (SRF) cavities.

  7. Designs of the frequency reference cavity for the AEI 10 m Prototype interferometer

    International Nuclear Information System (INIS)

    The AEI 10 m Prototype is in its designing phase and will provide a test-bed for very sensitive interferometric experiments, such as the sub-SQL interferometer. It will test new techniques to reach - and even surpass - the Standard Quantum Limit. The experience and knowledge that can be gained from this experiment can be applied to large-scale interferometric gravitational detectors to improve the detector sensitivities. In order for the sub-SQL interferometer to achieve the required sensitivity all limiting noise sources need to be suppressed sufficiently. Noise sources can include seismic noise, thermal noise, and laser noise; laser frequency noise will be the main focus of this document. The laser frequency noise will be suppressed to a level of 10-4 Hz/√Hz at 20 Hz dropping to below 10-6 Hz/√Hz at 1kHz. The proposed design to suppress the laser frequency noise with a ring cavity is described in this paper.

  8. Designs of the frequency reference cavity for the AEI 10 m Prototype interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kawazoe, Fumiko; Taylor, John Robert; Gering, Daniel; Graef, Christian; Heinzel, Gerhard; Mossavi, Kasem [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), 30167 Hannover (Germany); Bertolini, Alessandro; Born, Michael; Dahl, Katrin; Gossler, Stefan; Kranz, Oliver; Kuehn, Gerrit; Lueck, Harald; Schnabel, Roman; Wanner, Alexander; Westphal, Tobias [Leibniz Universitaet Hannover, 30167 Hannover (Germany); Chen Yanbei; Somiya, Kentaro [California Institute of Technology, Pasadena, CA 91125 (United States); Hild, Stefan; Strain, Kenneth, E-mail: fumiko.kawazoe@aei.mpg.d [University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

    2010-05-01

    The AEI 10 m Prototype is in its designing phase and will provide a test-bed for very sensitive interferometric experiments, such as the sub-SQL interferometer. It will test new techniques to reach - and even surpass - the Standard Quantum Limit. The experience and knowledge that can be gained from this experiment can be applied to large-scale interferometric gravitational detectors to improve the detector sensitivities. In order for the sub-SQL interferometer to achieve the required sensitivity all limiting noise sources need to be suppressed sufficiently. Noise sources can include seismic noise, thermal noise, and laser noise; laser frequency noise will be the main focus of this document. The laser frequency noise will be suppressed to a level of 10{sup -4} Hz/{radical}Hz at 20 Hz dropping to below 10{sup -6} Hz/{radical}Hz at 1kHz. The proposed design to suppress the laser frequency noise with a ring cavity is described in this paper.

  9. Insights to Superconducting Radio-Frequency Cavity Processing from First Principles Calculations and Spectroscopic Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Denise Christine [Northwestern Univ., Evanston, IL (United States)

    2013-03-01

    Insights to the fundamental processes that occur during the manufacturing of niobium superconducting radio-frequency (SRF) cavities are provided via analyses of density functional theory calculations and Raman, infrared, and nuclear magnetic resonance (NMR) spectra. I show that during electropolishing fluorine is bound and released by the reaction of the acid components in the solution: HF + H2SO4 <-> HFSO3 + H2O. This result implies that new recipes can possibly be developed on the principle of controlled release of fluorine by a chemical reaction. I also show that NMR or Raman spectroscopy can be used to monitor the free fluorine when polishing with the standard electropolishing recipe. Density functional theory was applied to calculate the properties of common processing impurities – hydrogen, oxygen, nitrogen, and carbon – in the niobium. These impurities lower the superconducting transition temperature of niobium, and hydride precipitates are at best weakly superconducting. I modeled several of the niobium hydride phases relevant to SRF cavities, and explain the phase changes in the niobium hydrogen system based on the charge transfer between niobium and hydrogen and the strain field inside of the niobium. I also present evidence for a niobium lattice vacancy serving as a nucleation center for hydride phase formation. In considering the other chemical impurities in niobium, I show that the absorption of oxygen into a niobium lattice vacancy is preferred over the absorption of hydrogen, which indicates that oxygen can block these phase nucleation centers. I also show that dissolved oxygen atoms can trap dissolved hydrogen atoms to prevent niobium hydride phase formation. Nitrogen and carbon were studied in less depth, but behaved similarly to oxygen. Based on these results and a literature survey, I propose a mechanism for the success of the low-temperature anneal applied to niobium SRF cavities. Finally, I

  10. Surface polishing of niobium for superconducting radio frequency (SRF) cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang [College of William and Mary, Williamsburg, VA (United States)

    2014-08-01

    Niobium cavities are important components in modern particle accelerators based on superconducting radio frequency (SRF) technology. The interior of SRF cavities are cleaned and polished in order to produce high accelerating field and low power dissipation on the cavity wall. Current polishing methods, buffered chemical polishing (BCP) and electro-polishing (EP), have their advantages and limitations. We seek to improve current methods and explore laser polishing (LP) as a greener alternative of chemical methods. The topography and removal rate of BCP at different conditions (duration, temperature, sample orientation, flow rate) was studied with optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). Differential etching on different crystal orientations is the main contributor to fine grain niobium BCP topography, with gas evolution playing a secondary role. The surface of single crystal and bi-crystal niobium is smooth even after heavy BCP. The topography of fine grain niobium depends on total removal. The removal rate increases with temperature and surface acid flow rate within the rage of 0~20 °C, with chemical reaction being the possible dominate rate control mechanism. Surface flow helps to regulate temperature and avoid gas accumulation on the surface. The effect of surface flow rate on niobium EP was studied with optical microscopy, atomic force microscopy (AFM), and power spectral density (PSD) analysis. Within the range of 0~3.7 cm/s, no significant difference was found on the removal rate and the macro roughness. Possible improvement on the micro roughness with increased surface flow rate was observed. The effect of fluence and pulse accumulation on niobium topography during LP was studied with optical microscopy, SEM, AFM, and PSD analysis. Polishing on micro scale was achieved within fluence range of 0.57~0.90 J/cm2, with pulse accumulation adjusted accordingly. Larger area treatment was proved possible by

  11. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    CERN Document Server

    Wen, Xin; Wang, Junmin

    2016-01-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power to 111 mW of 397.5 nm UV output. For LBO crystal, with 1.34 W of mode-matched 795 nm power, 770 mW of 397.5 nm UV output is achieved, implying a doubling efficiency of 57.4%. For BiBO crystal, with 323 mW of mode-matched 795 nm power, 116 mW of 397.5 nm UV output is achieved, leading to a doubling efficiency of 35.9%. The generated UV radiation has potential applications in the fields of quantum physics

  12. Cavity tuning characteristics of orthogonally polarized dual-frequency He-Ne laser at 1.15 μm

    Institute of Scientific and Technical Information of China (English)

    Zhengqi Zhao; Shulian Zhang; Yidong Tan; Yan Li

    2012-01-01

    The cavity tuning characteristics of orthogonally polarized dual-frequency He-Ne laser at 1.15 μm are presented.Vectorial-extension model based on semi-classical laser theory reveals that cavity tuning characteristics are related to beat frequency,relative excitation,and type of Ne isotope.Distortions of cavity tuning curves become moderate with the increase of beat frequency because of the weakening of the crosssaturation effect.Distortions are enhanced with the increase of relative excitation because of the combined action of the self-saturation and cross-saturation effects.By adopting dual-isotope Ne instead of monoisotoplic Ne,distortions are reduced because of the misalignment between peaks of the self-saturation and net gain coefficients.The theoretical calculations are in good agreement with the corresponding experimental results.%The cavity tuning characteristics of orthogonally polarized dual-frequency He-Ne laser at 1.15 μm are presented. Vectorial-extension model based on semi-classical laser theory reveals that cavity tuning characteristics are related to beat frequency, relative excitation, and type of Ne isotope. Distortions of cavity tuning curves become moderate with the increase of beat frequency because of the weakening of the cross-saturation effect. Distortions are enhanced with the increase of relative excitation because of the combined action of the self-saturation and cross-saturation effects. By adopting dual-isotope Ne instead of monoiso-toplic Ne, distortions are reduced because of the misalignment between peaks of the self-saturation and net gain coefficients. The theoretical calculations are in good agreement with the corresponding experimental results.

  13. The study of 670.7 nm red light generated by intracavity frequency doubling of a Q-switched Nd : YAlO{sub 3} laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Haiyong; Zhang Ge; Huang Chenghui; Wei Yong; Huang Lingxiong; Huang Yidong, E-mail: zhg@fjirsm.ac.c [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

    2009-02-21

    High-power 670.7 nm red light was obtained by intracavity frequency doubling of a Q-switched Nd : YAlO{sub 3} (Nd : YAP) laser with a critical phase matching ({theta} = 85.9{sup 0}, {phi} = 0{sup 0}) cut LBO. Experimental configurations using V-cavity and Z-cavity have been adopted for comparison. The highest output power of 19.7 W was achieved in the Z-cavity with optical-optical efficiency of 4%. Compared with the laser using an Nd : YAG crystal, the adoption of Nd : YAP simplified the laser system in the absence of a solid etalon and the Brewster plate. The output power stability of the red laser was investigated and the fluctuation was lower than 3% at the output power of 18 W an hour.

  14. Dual-frequency comb generation with differing GHz repetition rates by parallel Fabry-Perot cavity filtering of a single broadband frequency comb source

    Science.gov (United States)

    Mildner, Jutta; Meiners-Hagen, Karl; Pollinger, Florian

    2016-07-01

    We present a dual-comb-generator based on a coupled Fabry-Perot filtering cavity doublet and a single seed laser source. By filtering a commercial erbium-doped fiber-based optical frequency comb with CEO-stabilisation and 250 MHz repetition rate, two broadband coherent combs of different repetition rates in the GHz range are generated. The filtering doublet consists of two Fabry-Perot cavities with a tunable spacing and Pound-Drever-Hall stabilisation scheme. As a prerequisite for the development of such a filtering unit, we present a method to determine the actual free spectral range and transmission bandwidth of a Fabry-Perot cavity in situ. The transmitted beat signal of two diode lasers is measured as a function of their tunable frequency difference. Finally, the filtering performance and resulting beat signals of the heterodyned combs are discussed as well as the optimisation measures of the whole system.

  15. The green light generation by self-frequency-doubled Yb:YCOB crystal

    CERN Document Server

    Fang, Qiannan; Zhang, Huaijin; Wang, Jiyang

    2016-01-01

    Taking advantages of the broad emission bands of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of principle planes with the maximum effective nonlinear coefficient, the self-frequency-doubled green light based on the self-frequency-doubling behavior of Yb:YCOB was achieved with a maximum output power of 710 mW at 523 nm.

  16. Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Janardan Upadhyay, Larry Phillips, Anne-Marie Valente

    2011-09-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

  17. Numerical 2D And 3D Simulations of a Spherical Fabry–Pérot Resonator for Application as a Reference Cavity for Laser Frequency Stabilisation

    Directory of Open Access Journals (Sweden)

    Nitiss E.

    2015-06-01

    Full Text Available We report on the results of a numerical study of deformations of a spherical Fabry-Pérot cavity that can be used for laser frequency stabilisation. It is demonstrated that for a precise simulation of the cavity deformations a 3D model has to be used instead of a simpler 2D model, which employs simulation on the symmetry plane of the cavity. To lower the sensitivity to environmental perturbations, it is suggested to use a material with a low density and a high Young’s modulus. We also show that the mechanical resonance frequencies of the cavity are mainly determined by the size of the cavity.

  18. Stabilization and Shift of Frequency in an External Cavity Diode Laser with Solenoid-Assisted Saturated Absorption

    Institute of Scientific and Technical Information of China (English)

    HAN Shun-Li; CHENG Bing; ZHANG Jing-Fang; XU Yun-Fei; WANG Zhao-Ying; LIN Qiang

    2009-01-01

    A simple method to realize both stabilization and shift of the frequency in an external cavity diode laser (ECDL) is reported.Due to the Zeeman effect,the saturated absorption spectrum of Rb atoms in a magnetic field is shifted.This shift can be used to detune the frequency of the ECDL,which is locked to the saturated absorption spectrum.The frequency shift amount can be controlled by changing the magnetic field for a specific polarization state of the laser beam.The advantages of this tunable frequency lock include low laser power requirement,without additional power loss,cheapness,and so on.

  19. Stabilization and Shift of Frequency in an External Cavity Diode Laser with Solenoid-Assisted Saturated Absorption

    International Nuclear Information System (INIS)

    A simple method to realize both stabilization and shift of the frequency in an external cavity diode laser (ECDL) is reported. Due to the Zeeman effect, the saturated absorption spectrum of Rb atoms in a magnetic field is shifted. This shift can be used to detune the frequency of the ECDL, which is locked to the saturated absorption spectrum. The frequency shift amount can be controlled by changing the magnetic field for a specific polarization state of the laser beam. The advantages of this tunable frequency lock include low laser power requirement, without additional power loss, cheapness, and so on. (atomic and molecular physics)

  20. Numerical study of double-diffusion convection coupled to radiation in a square cavity filled with a participating grey gas

    Energy Technology Data Exchange (ETDEWEB)

    Mezrhab, A [Faculty of Science, Department of Physics, Laboratoire de Mecanique and Energetique, 60000 Oujda (Morocco); Lemonnier, D [ENSMA, Laboratoire d' Etudes Thermiques, 86961 Futuroscope Chasseneuil cedex (France); Meftah, S; Benbrik, A [Faculty of Hydrocarbons and Chemistry, University of Boumerdes (Algeria)], E-mail: mezrhab@fso.ump.ma

    2008-10-07

    This paper presents numerical solutions for the coupled radiation and natural convection heat transfer by double diffusion in a square cavity. The governing differential equations are solved by a finite-volume method, by adopting the SIMPLER algorithm for pressure-velocity coupling. The discrete ordinate method is used in modelling the radiative transfer equation. The working fluid is considered as grey, absorbing, emitting and not scattering. The walls of the enclosure are assumed to be opaque, diffuse and grey. A parametric study is performed to illustrate the influence of the Rayleigh number, the buoyancy number, the Lewis number and the optical thickness on the flow structure, the heat and mass transfer. The results obtained can be used as benchmark solutions for the validation of the codes treating the combined natural convection heat transfer by double diffusion and radiation.

  1. Numerical study of double-diffusion convection coupled to radiation in a square cavity filled with a participating grey gas

    International Nuclear Information System (INIS)

    This paper presents numerical solutions for the coupled radiation and natural convection heat transfer by double diffusion in a square cavity. The governing differential equations are solved by a finite-volume method, by adopting the SIMPLER algorithm for pressure-velocity coupling. The discrete ordinate method is used in modelling the radiative transfer equation. The working fluid is considered as grey, absorbing, emitting and not scattering. The walls of the enclosure are assumed to be opaque, diffuse and grey. A parametric study is performed to illustrate the influence of the Rayleigh number, the buoyancy number, the Lewis number and the optical thickness on the flow structure, the heat and mass transfer. The results obtained can be used as benchmark solutions for the validation of the codes treating the combined natural convection heat transfer by double diffusion and radiation

  2. Design of a re-entrant double-staggered ladder circuit for V-band coupled-cavity traveling-wave tubes

    Institute of Scientific and Technical Information of China (English)

    Liu Yang; Xu Jin; Lai Jian-Qiang; Xu Xiong; Shen Fei; Wei Yan-Yu; Huang Min-Zhi; Tang Tao; Gong Yu-Bin

    2012-01-01

    The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube.This structure has a wide bandwidth,a moderate interaction impedance,and excellent thermal dissipation properties,as well as easy fabrication.A well-matched waveguide coupler is proposed for the structure.Combining the design of attenuators,a full-scale three-dimensional circuit model for the V-band coupled-cavity travelingwave tube is constructed.The electromagnetic characteristics and the beam-wave interaction of this structure are investigated.The beam current is set to be 100 mA,and the cathode voltage is tuned from 16.8 kV to 15.8 kV.The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz.The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%,respectively.

  3. Diode-Pumped Compact cw Frequency-Doubled Nd:YAG Laser in the Watt Range at 473 nm

    Institute of Scientific and Technical Information of China (English)

    李平雪; 李德华; 张治国; 张世文

    2003-01-01

    We report a diode-pumped cw Nd:YAG laser operating on the 4F3/2-4I9/2 transition at 946nm, for which a maximum output power of 4.5 W with a slope efficiency of 21% is achieved at an incident pump power of 26 W.Two LiBsO5 (LBO) crystals of different lengths (3 × 3 × 10mm and 3 × 3 × 15 mm), cut for critical type Ⅰphase matching at room temperature, have been used for intracavity frequency doubling, and through optimization of the structure and elements of the cavity, a maximum single-ended blue output power of 1.1 W has been obtained with an optical conversion efficiency of 4.2%. A stability better than 4.8% with no mode hopping over a period of 2h has been achieved.

  4. Double-cavity radiometer for high-flux density solar radiation measurements.

    Science.gov (United States)

    Parretta, A; Antonini, A; Armani, M; Nenna, G; Flaminio, G; Pellegrino, M

    2007-04-20

    A radiometric method has been developed, suitable for both total power and flux density profile measurement of concentrated solar radiation. The high-flux density radiation is collected by a first optical cavity, integrated, and driven to a second optical cavity, where, attenuated, it is measured by a conventional radiometer operating under a stationary irradiation regime. The attenuation factor is regulated by properly selecting the aperture areas in the two cavities. The radiometer has been calibrated by a pulsed solar simulator at concentration levels of hundreds of suns. An optical model and a ray-tracing study have also been developed and validated, by which the potentialities of the radiometer have been largely explored.

  5. Double-cavity radiometer for high-flux density solar radiation measurements.

    Science.gov (United States)

    Parretta, A; Antonini, A; Armani, M; Nenna, G; Flaminio, G; Pellegrino, M

    2007-04-20

    A radiometric method has been developed, suitable for both total power and flux density profile measurement of concentrated solar radiation. The high-flux density radiation is collected by a first optical cavity, integrated, and driven to a second optical cavity, where, attenuated, it is measured by a conventional radiometer operating under a stationary irradiation regime. The attenuation factor is regulated by properly selecting the aperture areas in the two cavities. The radiometer has been calibrated by a pulsed solar simulator at concentration levels of hundreds of suns. An optical model and a ray-tracing study have also been developed and validated, by which the potentialities of the radiometer have been largely explored. PMID:17415384

  6. 高效LD侧面泵浦腔外倍频绿光激光器%Efficient Diode-Side-Pumped Extra-cavity-doubled Green Laser

    Institute of Scientific and Technical Information of China (English)

    伊肖静; 杨超; 陈檬; 李港

    2012-01-01

    To meet the demand in the fields of laser color display, laser processing, optical data storage, laser medical and scientific research, an efficient narrow pulse width diode-side-pumped extra-cavity-doubled green Nd: YAG/LBO laser has been developed successfully. We have analyzed and calculated the best focus parameters, and determined the best focal length of the lens. In our experiment, fundamental frequency output at 1 064 nm with average power 10. 7 W and single pulse energy 10. 7 mJ at repetition rate of 1 kHz are obtained, by using LD side-pumping technology and electro-optic Q-swith technology. In order to compensate for thermal depolarization, we added a quarter-wave plate in the cavity. On the basis of this, we do the exta-cavity-doubled experiment, using I -type temperature phase matched LBO crystal, which get a 6. 04 W green light output. The pulse-width is 21 ns at repetition rate of 1 kHz. The optical frequency conversion efficiency from IR to green laser is up to 59. 3%.%为满足激光加工、激光彩色显示、数据存储、医疗卫生和科研等领域对绿光激光器的需要,研制了一台高倍频效率、窄脉宽侧面泵浦腔外倍频的YAG/LBO绿光激光器.分析并计算了腔外最佳聚焦参数,确定了透镜的最佳聚焦焦距.实验中,利用808 nm激光二极管侧面泵浦Nd:YAG晶体,使用BBO晶体进行加压式调Q,采用四分之一波片补偿Nd:YAG晶体的热退偏,最终实现了重复频率1 kHz、输出功率10.7W的1 064 nm输出,最大单脉冲能量为10.7 mJ.在此基础上,采用Ⅰ类温度相位匹配LBO晶体对基频光进行腔外倍频,获得了重复频率1 kHz、脉宽21 ns、最大输出功率6.04 W的532 nm准连续绿光输出,倍频效率高达59.3%.

  7. Microwave photonic filter using multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency shift

    Science.gov (United States)

    Loh, K. K.; Yeo, K. S.; Shee, Y. G.

    2015-04-01

    A microwave photonic filter based on double-Brillouin-frequency spaced multiwavelength Brillouin-erbium fiber laser (BEFL) is experimentally demonstrated. The filter selectivity can be easily adjusted by tuning and apodizing the optical taps generated from the multiwavelength BEFL. Reconfiguration of different frequency responses are demonstrated.

  8. Microwave photonic filter using multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency shift

    Energy Technology Data Exchange (ETDEWEB)

    Loh, K. K.; Yeo, K. S.; Shee, Y. G. [Integrated Lightwave Research Group, Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    A microwave photonic filter based on double-Brillouin-frequency spaced multiwavelength Brillouin-erbium fiber laser (BEFL) is experimentally demonstrated. The filter selectivity can be easily adjusted by tuning and apodizing the optical taps generated from the multiwavelength BEFL. Reconfiguration of different frequency responses are demonstrated.

  9. A long-term frequency-stabilized erbium-fiber-laser-based optical frequency comb with an intra-cavity electro-optic modulator

    CERN Document Server

    Zhang, Y; Zhao, W; Meng, S; Fan, S; Zhang, L; Guo, G; Zhang, S; Jiang, H

    2014-01-01

    We demonstrate a home-made optical frequency comb based on an erbium-doped-fiber femtosecond laser with a ring cavity. The repetition rate of the laser is about 209 MHz determined by optical length of the laser cavity. By controlling an intra-cavity electro-optic modulator and a Piezo-transducer, the repetition rate can be stabilized with megahertz bandwidth in a range of 3 kilohertz, enabling long-term repetition rate phase-locking. The in-loop frequency instability of the repetition rate, limited by measurement system, is 1.3E-13 at 1 second integration time and inversely proportional to integration time for short terms. Using a common path f-2f interferometer, the carrier envelope offset (CEO) frequency of the frequency comb is obtained with a signal-to-noise ratio of 40 dB for 3 megahertz resolution spectrum. Stabilized CEO frequency exhibits a deviation of 0.6 milihertz at 1 second integration time.

  10. Systematic cavity design approach for a multi-frequency gyrotron for DEMO and study of its RF behavior

    Science.gov (United States)

    Kalaria, P. C.; Avramidis, K. A.; Franck, J.; Gantenbein, G.; Illy, S.; Pagonakis, I. Gr.; Thumm, M.; Jelonnek, J.

    2016-09-01

    High frequency (>230 GHz) megawatt-class gyrotrons are planned as RF sources for electron cyclotron resonance heating and current drive in DEMOnstration fusion power plants (DEMOs). In this paper, for the first time, a feasibility study of a 236 GHz DEMO gyrotron is presented by considering all relevant design goals and the possible technical limitations. A mode-selection procedure is proposed in order to satisfy the multi-frequency and frequency-step tunability requirements. An effective systematic design approach for the optimal design of a gradually tapered cavity is presented. The RF-behavior of the proposed cavity is verified rigorously, supporting 920 kW of stable output power with an interaction efficiency of 36% including the considerations of realistic beam parameters.

  11. Photonic Device Design Based on BBO for Ultrafast Frequency Doubling

    Science.gov (United States)

    Huang, Jin-Zhe; Yang, Zhong-Ying; Zhang, Liu-Yang; Pu, Shao-Zhi; Su, Lin

    2014-11-01

    Group velocity mismatch becomes the main obstacle for frequency conversion of ultrashort pulses due to dispersion. To solve the problem, one design is proposed for group velocity compensated second harmonic generation in a periodically modulated BBO crystal structure: the α-BBO/β-BBO multi-layer microstructure. The results show that the device can be well applied from the visible red to the near infrared region.

  12. Autonomous frequency stabilization of two extended cavity diode lasers at the potassium wavelength on a sounding rocket

    CERN Document Server

    Dinkelaker, Aline N; Schkolnik, Vladimir; Kenyon, Andrew; Lampmann, Kai; Wenzlawski, André; Windpassinger, Patrick; Hellmig, Ortwin; Wendrich, Thijs; Rasel, Ernst M; Giunta, Michele; Deutsch, Christian; Kürbis, Christian; Smol, Robert; Wicht, Andreas; Krutzik, Markus; Peters, Achim

    2016-01-01

    We have developed, assembled, and flight-proven a stable, compact, and autonomous extended cavity diode laser (ECDL) system designed for atomic physics experiments in space. To that end, two micro-integrated ECDLs at 766.7 nm were frequency stabilized during a sounding rocket flight by means of frequency modulation spectroscopy (FMS) of 39^K and offset locking techniques based on the beat note of the two ECDLs. The frequency stabilization as well as additional hard- and software to test hot redundancy mechanisms were implemented as part of a state-machine, which controlled the experiment completely autonomously throughout the entire flight mission.

  13. 0.5W CW single frequency blue at 486 nm via SHG with net conversion of 81.5% from the NIR using a 30mm PPMgO:SLT crystal in a resonant cavity

    Science.gov (United States)

    Khademian, Ali; Jadhav, Shilpa; Shiner, David

    2015-02-01

    A single frequency fiber Bragg grating (FBG) stabilized laser at 972 nm is coupled into a doubling ring cavity with an optical length of 138 mm, a 91% input coupler, a 30 mm long Brewster cut magnesium doped periodically poled lithium tantalate (PPMgO:SLT) crystal and a high reflector. The cavity buildup is 37 and loss is 0.63%. The cavity is monitored, controlled and locked with a single chip processor. With IR power of 572 mW in the input fiber, 466 mW blue output is obtained, giving 81.5% net efficiency. The blue and IR beams are separated by refraction at the crystal's Brewster surface with negligible loss and without the need for dichroic optics.

  14. Sub-doppler spectroscopy with a frequency-doubled tunable single-frequency Nd:YAG laser

    International Nuclear Information System (INIS)

    In the authors system, the master laser is a diode-laser-pumped mini-YAG/sup 3/ with single-frequency pulsed output power of 50 mW, while the slave oscillator is a modified commercial (Quanta-Ray DCR-1A) Nd:YAG systems which outputs 0.7 J with a single amplifier stage. Cavity matching of the master and slave resonators is achieved by using a feed-back scheme similar to the polarization technique introduced by a previous work. The authors' approach, which relies on the presence of finite strain in the mini-YAG crystal resonator, detects the depolarization of light reflected by this resonator whenever the incident wave matches the Fabry-Perot resonance. Once locked, the longterm frequency stability of the system is clearly governed by the temperature stability of the mini-YAG laser (a change in temperature of only 0.010 results in a frequency drift of 31 MHz)

  15. In-situ plasma processing to increase the accelerating gradients of superconducting radio-frequency cavities

    Science.gov (United States)

    Doleans, M.; Tyagi, P. V.; Afanador, R.; McMahan, C. J.; Ball, J. A.; Barnhart, D. L.; Blokland, W.; Crofford, M. T.; Degraff, B. D.; Gold, S. W.; Hannah, B. S.; Howell, M. P.; Kim, S.-H.; Lee, S.-W.; Mammosser, J.; Neustadt, T. S.; Saunders, J. W.; Stewart, S.; Strong, W. H.; Vandygriff, D. J.; Vandygriff, D. M.

    2016-03-01

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. In this article, the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus are discussed.

  16. High Power Diode-End-Pumped Nd:YAG 946-nm Laser and Its Efficient Frequency Doubling

    Institute of Scientific and Technical Information of China (English)

    ZHOU Rui; ZHAO Shi-Yong; CAI Zhi-Qiang; ZHANG Qiang; WEN Wu-Qi; DING Xin; WANG Peng; DING Li-Li; YAO Jian-Quan

    2005-01-01

    @@ We report a high power operation of the 4F3/2 → 4I9/2 transition in diode-end-pumped laser at 946nm. The maximum output of5.1 W is obtained with a short linear plano-concave cavity, and the slope efficiency is 24.5%at incident pump power of 23.3 W. To our knowledge, this is the highest value of the LD-pumped Nd:YAG 946nm lasers that employ the conversional Nd:YAG rod as the gain medium. By intracavity frequency doubling with an LBO crystal, up to 982mW cw output power in the blue spectral range at 473nm is achieved at an incident pump power of 10.9 W with a compact three-element cavity, leading to optical-to-optical conversion efficiency of 9%. The conversion efficiency should be increased to 15.1%, if the rather low absorption coefficient of this Nd:YAG is considered.

  17. 6.2-W deep blue light generation by intracavity frequency-doubled Nd:GdVO4 using BiBO

    Institute of Scientific and Technical Information of China (English)

    Yanfei Lü; Xihe Zhang; Zhihai Yao; Fengdong Zhang

    2007-01-01

    @@ Efficient continuous-wave (CW) intracavity frequency doubling of a diode-end-pumped Nd:GdVO4 laser operating on 4F3/2 - 4I9/2 transitions at 912 nm has been demonstrated. A symmetrical cavity with two laser rods is designed, which divides the pump power between the two laser rods, allowing for greater power scalability. An 18-mm-long BiBO crystal, cut for critical type Ⅰ phase matching, is used for the intracavity frequency-doubled laser. A maximum output power of 6.2 W in the blue spectral range at 456 nm has been achieved with the pump power of 36 W. The beam quality M2 value is 2.5 in both horizontal and vertical directions. The ellipticity of the deep blue laser is 0.98, and the power stability is better than 3.2% at the maximum output power.

  18. LD side-pumped intracavity frequency-doubled high power Nd:YAG green laser based on acousto-optic Q-switch

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng-chuan; FAN Xiu-wei; XUE Lin; CHAI Hong-liang; HE Jing-liang

    2006-01-01

    A highly efficient and high power green laser generated by intracavity frequency doubling of a diode-side pumped Q-switched Nd:YAG laser has been demonstrated. In the simple L-shaped cavity geometry,the maximum green output power of 28.5 W was obtained with a pulse width of 95 ns at a pulse repetition rate of 10 kHz by using a LBO crystal for frequency doubling,corresponding to a conversion efficiency of 11% from diode pump power to pulse green power. At a pulse repetition rate of 1 kHz,6.9 mJ of pulse energy,25 ns of pulse duration and 276 kW of peak power were obtained.

  19. All-solid-state continuous-wave frequency-doubled Nd:YAG/LBO laser with 1.2 W output power at 561 nm

    International Nuclear Information System (INIS)

    We demonstrate for the first time the generation of yellow-green laser at 561 nm in critically type-I phase matching LBO with intracavity frequency doubling of a diode-pumped Nd:YAG laser operated at 1123 nm under room temperature in a compact three-fold cavity. As high as 1.2 W of continuous wave output at 561 nm is achieved with an incident pump power of 10 W. The total optical to optical conversion efficiency is up to 13.3% and the stability of output power is better than 3% in 3 h. To the best of our knowledge, this is the first Watt-level 561 nm yellow laser generation by frequency doubling of Nd:YAG laser

  20. 3.8 W of cw blue light generated by intracavity frequency doubling of a 946-nm Nd:YAG laser with LBO

    Science.gov (United States)

    Chen, Y.; Peng, H.; Hou, W.; Peng, Q.; Geng, A.; Guo, L.; Cui, D.; Xu, Z.

    2006-05-01

    Efficient cw intracavity frequency doubling of a diode-end-pumped Nd:YAG laser operating on 4 F 3/2→4 I 9/2 transitions at 946 nm has been demonstrated. A symmetrical cavity with two composite laser rods was designed, which divides the pump power between the two composite laser rods, allowing for greater power scalability. A 30-mm-long LiB3O5 (LBO) crystal, cut for critical type I phase matching at 57 °C, was used for the intracavity frequency doubling of the laser. A maximum output power of 3.8 W in the blue spectral range at 473 nm has been achieved at 39 W of pump power. The beam quality M2 value is 2.3 in both horizontal and vertical dimensions.

  1. Frequency stabilization based on high finesse glass-ceramic Fabry-Perot cavity for a 632.8-nm He-Ne laser

    Science.gov (United States)

    Fu, Tingting; Yang, Kaiyong; Tan, Zhongqi; Luo, Zhifu; Wu, Suyong

    2014-12-01

    A frequency stabilization technique for a 632.8nm He-Ne laser with a high finesse Fabry-Perot cavity is introduced in this paper. The resonant frequency of the cavity is taken as the frequency standard .In this system the Fabry-Perot cavity is composed of a glass-ceramic spacer, with thermal expansion coefficient smaller than 2×10-8/°C , which means an excellent thermal stabilization which greatly decreases the thermal impacts on the cavity length in the desired constant-temperature environment.The intra-cavity spherical mirror is specially designed, which makes the Fabry-cavity a sensor element in our subsequent experiments for a new practical optical accelerometer .Both cavity mirrors were custom made in our laboratory which have reflectivities greater than 99.995% at 632.8nm, so the Fabry-Perot cavity has a finesse of about 62830. The half-maximum transmission line width is about 55.48 KHz and the free spectral range is 3.5GHz .In the experimental setup, we adopt the frequency stabilization circuit with small dithering .With proper dithering voltage, the laser can be precisely locked to the Fabry-Perot cavity minimum reflection point. Theoretically the frequency stability can reach 10-10 order.

  2. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  3. Filter-less frequency-doubling microwave signal generator with tunable phase shift

    Science.gov (United States)

    Li, Yueqin; Pei, Li; Li, Jing; Wang, Yiqun; Yuan, Jin

    2016-07-01

    A prototype for frequency-doubling microwave signal generator with tunable phase shift based on a filter-less architecture is proposed and analyzed. In the proposal, one dual parallel polarization modulator is used as the key component to generate two ±1st order sidebands along the orthogonal polarization directions with suppressed carrier. Then the polarization states of the two sidebands are aligned with the principal axes of an electro-optical phase modulator (EOPM). Tunable phase shift is implemented by controlling the direct current voltage applied to the EOPM. Without using any filters or wavelength-dependent components, the system possesses good frequency tunability and it can be applied to multi-wavelength operation. Taking advantage of the ability of frequency multiplication, the frequency tuning range can be wider than the operation bandwidth of the modulator. By theoretical analyses and simulated verifications, a frequency-doubling microwave signal ranging from 22 to 40 GHz with full range phase shift is achieved.

  4. LHC Crab Cavity Coupler Test Boxes

    CERN Document Server

    Mitchell, James; Burt, Graeme; Calaga, Rama; Macpherson, Alick; Montesinos, Eric; Silva, Subashini; Tutte, Adam; Xiao, Binping

    2016-01-01

    The LHC double quarter wave (DQW) crab cavities have two different types of Higher Order Mode (HOM) couplers in addition to a fundamental power coupler (FPC). The FPC requires conditioning, so to achieve this we have designed a radio-frequency (RF) quarter wave resonator to provide high transmission between two opposing FPCs. For the HOM couplers we must ensure that the stop-band filter is positioned at the cavity frequency and that peak transmission occurs at the same frequencies as the strongest HOMs. We have designed two test boxes which preserve the cavity spectral response in order to test the couplers.

  5. Focused-ion-beam nanostructured photonic cavities for integrated lasers in crystalline double tungstate channel waveguides

    NARCIS (Netherlands)

    Ay, F.; Geskus, D.; Iñurrategui, I.; Aravazhi, S.; Pollnau, M.

    2011-01-01

    FIB milling of deep grating structures in KGLW:Yb3+ has been optimized to achieve the first on-chip integrated laser in crystalline potassium double tungstate. An integrated waveguide laser with 33% slope efficiency was demonstrated in KGLW:Yb3+.

  6. Fabrication of 30 nm pitch imprint moulds by frequency doubling for nanowire arrays

    International Nuclear Information System (INIS)

    We report the fabrication of 30 nm pitch nanowire array imprint moulds by spatial frequency doubling a 60 nm pitch array generated by electron beam lithography. We have successfully fabricated nanowire arrays at a 30 nm pitch, which is targeted for the year 2020 by the International Technology Roadmap for Semiconductors, with an average line-width of 17 nm and a 3σ line width roughness (LWR) of 4.0 nm. In contrast to previously reported procedures, our spatial frequency doubling technique produces electrically isolated nanowires that are appropriate for crossbar circuits

  7. Intracavity frequency doubling of CW Ti:Sapphire laser utilising BiBO nonlinear crystal

    DEFF Research Database (Denmark)

    Thorhauge, Morten; Mortensen, Jesper Liltorp; Tidemand-Lichtenberg, Peter;

    Utilising BiBO nonlinear crystal frequency doubling a Ti:Sapphire CW laser gave 100 mW at 405 nm and 53 mW at 392 nm. Stability proved excellent without servo control. Broad tunability was shown around 392 nm.......Utilising BiBO nonlinear crystal frequency doubling a Ti:Sapphire CW laser gave 100 mW at 405 nm and 53 mW at 392 nm. Stability proved excellent without servo control. Broad tunability was shown around 392 nm....

  8. Continuous-Wave Green Laser of 9.9W by Intracavity Frequency Doubling in Laser Diode Single-End-Pumped Nd:YVO4/LBO

    Institute of Scientific and Technical Information of China (English)

    BAI Yang; LI Long; CHEN Hao-Wei; YANG Zhi; BAI Jin-Tao

    2004-01-01

    @@ A maximum of 9.9 W cw TEM00 output at 532nm laser has been obtained by intracavity frequency doubling with LBO in laser-diode single-end-pumped Nd:YVO4. The Nd:YVO4/LBO green laser has a simple three mirror V-fold cavity structure. The optical-optical conversion efficiency was 34.8%. Based on the equation of thermal conduction, a general solution for the laser-crystal interior temperature distribution is obtained by the semi-analytical thermal analysis method.

  9. Analysis of entropy generation for double diffusive MHD convection in a square cavity with isothermal hollow cylinder

    Science.gov (United States)

    Mojumder, Satyajit; Saha, Sourav; Saha, Sumon

    2016-07-01

    Entropy optimization is a major concern for designing modern thermal management system. In the present work, entropy analysis in a square cavity with an isothermal hollow cylinder at the center is carried out for magneto-hydrodynamic (MHD) double diffusive convection. Galerkin weighted residuals method of finite element formulation is adopted for the numerical solution. Entropies due to fluid flow, heat, and mass transfer are computed for wide range of Hartmann (0 ≤ Ha ≤ 50) and Lewis numbers (1 ≤ Le ≤ 15), and buoyancy ratios (-5 ≤ N ≤ 5) at constant Rayleigh and Prandtl numbers. It is found that the influence of buoyancy ratio is prominent on entropy generation, which also depends on both Lewis and Hartmann numbers. The ratio N = -1 shows minimum entropy generation for any combination of Lewis and Hartman numbers. Visualization of isentropic contours and the variation of total entropy with the governing parameters provide remarkable evidences of entropy optimization.

  10. Fano Resonance Based on Metal-Insulator-Metal Waveguide-Coupled Double Rectangular Cavities for Plasmonic Nanosensors.

    Science.gov (United States)

    Zhang, Zhidong; Luo, Liang; Xue, Chenyang; Zhang, Wendong; Yan, Shubin

    2016-01-01

    A refractive index sensor based on metal-insulator-metal (MIM) waveguides coupled double rectangular cavities is proposed and investigated numerically using the finite element method (FEM). The transmission properties and refractive index sensitivity of various configurations of the sensor are systematically investigated. An asymmetric Fano resonance lineshape is observed in the transmission spectra of the sensor, which is induced by the interference between a broad resonance mode in one rectangular and a narrow one in the other. The effect of various structural parameters on the Fano resonance and the refractive index sensitivity of the system based on Fano resonance is investigated. The proposed plasmonic refractive index sensor shows a maximum sensitivity of 596 nm/RIU. PMID:27164101

  11. Fano Resonance Based on Metal-Insulator-Metal Waveguide-Coupled Double Rectangular Cavities for Plasmonic Nanosensors

    Directory of Open Access Journals (Sweden)

    Zhidong Zhang

    2016-05-01

    Full Text Available A refractive index sensor based on metal-insulator-metal (MIM waveguides coupled double rectangular cavities is proposed and investigated numerically using the finite element method (FEM. The transmission properties and refractive index sensitivity of various configurations of the sensor are systematically investigated. An asymmetric Fano resonance lineshape is observed in the transmission spectra of the sensor, which is induced by the interference between a broad resonance mode in one rectangular and a narrow one in the other. The effect of various structural parameters on the Fano resonance and the refractive index sensitivity of the system based on Fano resonance is investigated. The proposed plasmonic refractive index sensor shows a maximum sensitivity of 596 nm/RIU.

  12. Lattice Boltzmann simulation of double diffusive natural convection in a square cavity with a hot square obstacle

    Institute of Scientific and Technical Information of China (English)

    Mohsen Nazari; Ladan Louhghalam; Mohamad Hassan Kayhani

    2015-01-01

    Double diffusion convection in a cavity with a hot square obstacle inside is simulated using the lattice Boltzmann method. The results are presented for the Rayleigh numbers 104,105 and 106, the Lewis numbers 0.1, 2 and 10 and aspect ratio A (obstacle height/cavity height) of 0.2, 0.4 and 0.6 for a range of buoyancy number N=0 to−4 with the effect of opposing flow. The results indicate that for|N|b 1, the Nusselt and Sherwood numbers decrease as buoyancy ratio increases, while for|N|N 1, they increase with|N|. As the Lewis number increases, higher buoyan-cy ratio is required to overcome the thermal effects and the minimum value of the Nusselt and Sherwood num-bers occur at higher buoyancy ratios. The increase in the Rayleigh or Lewis number results in the formation of the multi-cell flow in the enclosure and the vortices wil vanish as|N|increases.

  13. Frequency Characteristics of Double-Walled Carbon Nanotube Resonator with Different Length

    OpenAIRE

    Jun-Ha LEE; Jeong-Won KANG; Kim, Jin-Tae

    2016-01-01

    In this paper, we have conducted classical molecular dynamics simulations for DWCNTs of various wall lengths to investigate their use as ultrahigh frequency nano-mechanical resonators. We sought to determine the variations in the frequency of these resonators according to changes in the DWCNT wall lengths. For a double-walled carbon nanotube resonator with a shorter inner nanotube, the shorter inner nanotube can be considered to be a flexible core, and thus, the length influences the fundamen...

  14. 589-nm yellow laser generation by intra-cavity sum-frequency mixing in a T-shaped Nd:YAG laser cavity

    Institute of Scientific and Technical Information of China (English)

    Xiuyan Chen; Xiu Li; Haolei Zhang; Haowei Chen; Jintao Bai; Zhaoyu Ren

    2009-01-01

    To obtain high power 589-nm yellow laser,a T-shaped thermal-insensitive cavity is designed.The optimal power ratio of 1064- and 1319-nm beams is considered and the fundamental spot size distribution from the output mirror to the two laser rods are calculated and simulated,respectively.As a result,a 589-nm yellow laser with the average output power of 5.7 W is obtained in the experiment when the total pumping power is 695 W.The optical-to-optical conversion efficiency from the fundamental waves to the sum frequency generation is about 15.2% and the pulse width is 150 ns at the repetition rate of 18 kHz.The instability of the yellow laser is also measured,which is less than 2% within 3 h.The beam quality factors are M2x =4.96 and M2y= 5.08.

  15. Coherent-state storage and retrieval between superconducting cavities using parametric frequency conversion

    International Nuclear Information System (INIS)

    In superconducting quantum information, machined aluminum superconducting cavities have proven to be a well-controlled, low-dissipation electromagnetic environment for quantum circuits such as qubits. They can possess large internal quality factors, Qint > 108, and present the possibility of storing quantum information for times far exceeding those of microfabricated circuits. However, in order to be useful as a storage element, these cavities require a fast “read/write” mechanism—in other words, they require tunable coupling between other systems of interest such as other cavity modes and qubits, as well as any associated readout hardware. In this work, we demonstrate these qualities in a simple dual cavity architecture in which a low-Q “readout” mode is parametrically coupled to a high-Q “storage” mode, allowing us to store and retrieve classical information. Specifically, we employ a flux-driven Josephson junction-based coupling scheme to controllably swap coherent states between two cavities, demonstrating full, sequenced control over the coupling rates between modes

  16. Coherent-state storage and retrieval between superconducting cavities using parametric frequency conversion

    Energy Technology Data Exchange (ETDEWEB)

    Sirois, A. J. [National Institute of Standard and Technology, Boulder, Colorado 80305 (United States); University of Colorado - Boulder, Colorado 80309 (United States); Castellanos-Beltran, M. A.; DeFeo, M. P.; Ranzani, L.; Lecocq, F.; Simmonds, R. W.; Teufel, J. D.; Aumentado, J. [National Institute of Standard and Technology, Boulder, Colorado 80305 (United States)

    2015-04-27

    In superconducting quantum information, machined aluminum superconducting cavities have proven to be a well-controlled, low-dissipation electromagnetic environment for quantum circuits such as qubits. They can possess large internal quality factors, Q{sub int} > 10{sup 8}, and present the possibility of storing quantum information for times far exceeding those of microfabricated circuits. However, in order to be useful as a storage element, these cavities require a fast “read/write” mechanism—in other words, they require tunable coupling between other systems of interest such as other cavity modes and qubits, as well as any associated readout hardware. In this work, we demonstrate these qualities in a simple dual cavity architecture in which a low-Q “readout” mode is parametrically coupled to a high-Q “storage” mode, allowing us to store and retrieve classical information. Specifically, we employ a flux-driven Josephson junction-based coupling scheme to controllably swap coherent states between two cavities, demonstrating full, sequenced control over the coupling rates between modes.

  17. Passively Q-switched Self-frequency Doubling NYAB laser with GaAs Saturable Absorber

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shengzhi(赵圣之); ZHENG Jiaan(郑加安); CHEN Lei(陈磊); CHENG Zhenxiang(程振祥); CHEN Huanchu(陈焕矗)

    2002-01-01

    By using a passive Q-switch with GaAs saturable absorber, the Q-switched self-frequency doubling NYAB laser at 0.531μm has been successfully realized. The pulse width and the single pulse energy are measured. The numerical solutions of the coupling wave rate equations are in agreement with the experimental results.

  18. An evaluation of algorithms designed to classify the results from frequency doubling perimetry

    NARCIS (Netherlands)

    Muskens, RPHM; Heeg, GP; Jansonius, NM

    2004-01-01

    All previously published algorithms for the interpretation of frequency doubling perimetry test results were compared in full-threshold mode in a large group of glaucoma patients (n = 452) and normal subjects (n = 237). Areas under the receiver-operating characteristic (ROC) curve ranged from 0.86 t

  19. Frequency doubling perimetry screening mode compared to the full-threshold mode

    NARCIS (Netherlands)

    Stoutenbeek, R; Heeg, GP; Jansonius, NM

    2004-01-01

    The diagnostic performance of the frequency doubling perimetry (FDT) C20-1 screening mode was compared to that of the C20 full-threshold mode. For the number of defects p <1% in the total deviation plot, both modes appeared to perform similarly in terms of sensitivity, specificity, and area under th

  20. 83 W yellow—green laser at 556 nm from frequency-doubling of a Q-switched Nd:YAG laser at 1112 nm in LBO

    Science.gov (United States)

    Wang, Z. C.; Xu, J. L.; Bo, Y.; Peng, Q. J.; Xie, S. Y.; Xu, Y. T.; Yang, F.; Zhang, J. Y.; Cui, D. F.; Xu, Z. Y.

    2011-11-01

    We demonstrate a high power 556 nm yellow-green laser by intracavity frequency doubled of the diode-pumped 1112 nm Nd:YAG laser in a symmetrical L-shaped flat-flat cavity. The coatings of the resonator mirrors were carefully designed to achieve efficient operation of fundamental wavelength of the laser at 1112 nm. By using a type-II phase matching LBO nonlinear crystal as the frequency-doubler, the maximum output power of the 556 nm laser was measured to be as high as 83 W with a pulse repetition frequency (PRF) of 10 kHz under incident pump power of 1150 W, corresponding to an optical-to-optical conversion efficiency of about 7.2%. The fluctuation of output power was less than 2% over 30 min.

  1. Development of a Cryogenic Radiation Detector for Mapping Radio Frequency Superconducting Cavity Field Emissions

    CERN Document Server

    Dotson, Danny W

    2005-01-01

    There is a relationship between field emissions in a Super Conducting RF cavity and the production of radiation (mostly X-rays). External (room temperature) detectors are shielded from the onset of low energy X-rays by the vacuum and cryogenic stainless steel module walls. An internal measuring system for mapping field emissions would assist scientists and engineers in perfecting surface deposition and acid washing module surfaces. Two measurement systems are undergoing cryogenic testing at JLab. One is an active CsI photodiode array and the second is an X-ray film camera. The CsI array has operated sucessfully in a cavity in liquid Helium but saturated at higher power due to scattering in the cavity. A shield with an aperature similar to the X-ray film detector is being designed for the next series of tests which will be completed before PAC-05.

  2. Cavity piezomechanical strong coupling and frequency conversion on an aluminum nitride chip

    Science.gov (United States)

    Zou, Chang-Ling; Han, Xu; Jiang, Liang; Tang, Hong X.

    2016-07-01

    Schemes to achieve strong coupling between mechanical modes of aluminum nitride microstructures and microwave cavity modes due to the piezoelectric effect are proposed. We show that the strong-coupling regime is feasible for an on-chip aluminum nitride device that is either enclosed by a three-dimensional microwave cavity or integrated with a superconducting coplanar resonator. Combining with optomechanics, the piezomechanical strong coupling permits coherent conversion between microwave and optical modes with high efficiency. Hence, the piezomechanical system will be an efficient transducer for applications in hybrid quantum systems.

  3. Cavity piezomechanical strong coupling and frequency conversion on an aluminum nitride chip

    CERN Document Server

    Zou, Chang-Ling; Jiang, Liang; Tang, Hong X

    2016-01-01

    Schemes to achieve strong coupling between mechanical modes of aluminum nitride microstructures and microwave cavity modes due to the piezoelectric effect are proposed. We show that the strong coupling regime is feasible for an on-chip aluminum nitride device that is either enclosed by a three-dimensional microwave cavity or integrated with a superconducting coplanar resonator. Combining with optomechanics, the piezomechanical strong coupling permits coherent conversion between microwave and optical modes with high efficiency. Hence, the piezomechanical system will be an efficient transducer for applications in hybrid quantum systems.

  4. Translocation frequency of double-stranded DNA through a solid-state nanopore

    CERN Document Server

    Bell, Nicholas A W; Keyser, Ulrich F

    2015-01-01

    Solid-state nanopores are single molecule sensors that measure changes in ionic current as charged polymers such as DNA pass through. Here, we present comprehensive experiments on the length, voltage and salt dependence of the frequency of double-stranded DNA translocations through conical quartz nanopores with mean opening diameter 15 nm. We observe an entropic barrier limited, length dependent translocation frequency at 4M LiCl salt concentration and a drift-dominated, length independent translocation frequency at 1M KCl salt concentration. These observations are described by a unifying convection-diffusion equation which includes the contribution of an entropic barrier for polymer entry.

  5. Clinical usefulness of transpapillary removal of common bile duct stones by frequency doubled double pulse Nd: YAG laser

    Institute of Scientific and Technical Information of China (English)

    Tae Hyeon Kim; Hyo Jeong Oh; Chang-Soo Choi; Dong Han Yeom; Suck Chei Choi

    2008-01-01

    AIM: To study the efficacy and the safety of laser lithotripsy without direct visual control by using a balloon catheter in patients with bile duct stones that could not be extracted by standard technique.METHODS: The seventeen patients (7 male and 10 female; mean age 67.8 years) with difficult common bile duct (CBD) stones were not amenable for conventional endoscopic maneuvers such as sphincterotomy and mechanical lithotripsy were included in this study. Laser wavelengths of 532 nm and 1064 nm as a double pulse were applied with pulse energy of 120 mJ. The laser fiber was advanced under fluoroscopic control through the ERCP balloon catheter. Laser lithotripsy was continued until the fragment size seemed to be less than 10 mm.Endoscopic extraction of the stones and fragments was performed with the use of the Dormia basket and balloon catheter.RESULTS: Bile duct clearance was achieved in 15 of 17 patients (88%). The mean number of treatment sessions was 1.7 ± 0.6. Endoscopic stone removal could not be achieved in 2 patients (7%). Adverse effects were noted in three patients (hemobilia, pancreatitis, and cholangitis).CONCLUSION: The Frequency Doubled Double Pulse Nd:YAG (FREDDY) laser may be an effective and safe technique in treatment of difficult bile duct stones.

  6. Advanced Heat Transfer Studies in Superfluid Helium for Large-scale High-yield Production of Superconducting Radio Frequency Cavities

    CERN Document Server

    Peters, Benedikt J; Schirm, Karl-Martin; Koettig, Torsten

    Oscillating Superleak Transducers (OSTs) can be used to localize quenches in superconducting radio frequency cavities. In the presented work the occurring thermal effects during such events are investigated both theoretically and experimentally. In the theoretical part the entire heat transfer process from the heat generation to the detection is covered. The experimental part focuses on the effects in superfluid helium. Previous publications observed the detection of an OST signal that was faster than the second sound velocity. This fast propagation could be verified in dedicated small scale experiments. Resistors were used to simulate the quench spots under controlled conditions. The three dimensional propagation of second sound was linked to OST signals for the first time, which improves the understanding of the OST signal and allows to gather information about the heating pulse. Additionally, OSTs were used as a tool for quench localisation on a real size cavity. Their sensitivity as well as the time resol...

  7. Efficient continuous-wave nonlinear frequency conversion in high-Q Gallium Nitride photonic crystal cavities on Silicon

    CERN Document Server

    Mohamed, Mohamed Sabry; Carlin, Jean-François; Minkov, Momchil; Gerace, Dario; Savona, Vincenzo; Grandjean, Nicolas; Galli, Matteo; Houdré, Romuald

    2016-01-01

    We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG) and third harmonic generation (THG) in suspended gallium nitride slab photonic crystal (PhC) cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4$\\times10^{4}$, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving normalized conversion efficiency of 2.4$\\times10^{-3}$ $W^{-1}$, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  8. Wideband Cavity Backed Spiral Antenna for Stepped Frequency Ground Penetrating Radar

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne; Lenler-Eriksen, Hans-Rudolph

    2005-01-01

    A 1.7 turn cavity backed coplanar waveguide to coplanar strip-fed logarithmic uniplanar spiral antenna is presented and compared to a 1.5 turn spiral antenna. The 1.7 turn spiral antenna has a wide beamwidth, are circular polarised and has a bandwidth with a return loss better than 6 d...

  9. Improving picogram mass sensitivity via frequency doubling in coupled silicon micro-cantilevers

    International Nuclear Information System (INIS)

    Two geometrically different cantilevers, with primary frequencies of 182.506 kHz (u-shaped cantilever for sensing) and 372.503 kHz (rectangular cantilever for detecting), were coupled by two symmetrical coupling overhangs for oscillation-based mass sensing verification with phase-locking. Based on a lumped element model, a theoretical expression, containing a nonlinear spring constant and a term corresponding to the effect of the coupling spring, was proposed to consider the factors influencing the entrainment range, which is defined as a plateau with a frequency ratio (resonant frequency of rectangular cantilever to that of u-shaped cantilever) of 2.000 in present study. A picogram order mass sensing by applying a polystyrene microsphere as a small mass perturbation onto the tip of the u-shaped cantilever was demonstrated. By varying driving voltages, two entrainment regions with and without microsphere were experimentally measured and comparatively shown. At a driving voltage of 1 Vpp, when the u-shaped cantilever was excited at its shifted frequency of 180.29 kHz, the frequency response of the coupled rectangular cantilever had a peak at double the shifted frequency of 360.58 kHz of the u-shaped cantilever. The frequency shift for picogram mass sensing was thus doubled from 2560 Hz to 5133 Hz due to phase-locking. A mass of 3.732 picogram was derived based on the doubled frequency shift corresponding to a calculated mass of 3.771 picogram from measured diameter and reported density. Both experimental demonstration and theoretical discussions from the viewpoint of entrainment range elicits the possibility of increasing the mass sensitivity via phase-locking in the coupled silicon micro-cantilevers. (paper)

  10. Coherent continuous-wave dual-frequency high-Q external-cavity semiconductor laser for GHz-THz applications.

    Science.gov (United States)

    Paquet, Romain; Blin, Stéphane; Myara, Mikhaël; Gratiet, Luc Le; Sellahi, Mohamed; Chomet, Baptiste; Beaudoin, Grégoire; Sagnes, Isabelle; Garnache, Arnaud

    2016-08-15

    We report a continuous-wave highly-coherent and tunable dual-frequency laser emitting at two frequencies separated by 30 GHz to 3 THz, based on compact III-V diode-pumped quantum-well surface-emitting semiconductor laser technology. The concept is based on the stable simultaneous operation of two Laguerre-Gauss transverse modes in a single-axis short cavity, using an integrated sub-wavelength-thick metallic mask. Simultaneous operation is demonstrated theoretically and experimentally by recording intensity noises and beat frequency, and time-resolved optical spectra. We demonstrated a >80  mW output power, diffraction-limited beam, narrow linewidth of 45  dB), and low intensity noise class-A dynamics of <0.3% rms, thus opening the path to a compact low-cost coherent GHz to THz source development. PMID:27519080

  11. A 23.75-GHz frequency comb with two low-finesse filtering cavities in series for high resolution spectroscopy

    Institute of Scientific and Technical Information of China (English)

    侯磊; 韩海年; 王薇; 张龙; 庞利辉; 李德华; 魏志义

    2015-01-01

    A laser frequency comb with several tens GHz level is demonstrated, based on an Yb-doped femtosecond fiber laser and two low-finesse Fabry–P´erot cavities (FPCs) in series. The original 250-MHz mode-line-spacing of the source comb is filtered to 4.75 GHz and 23.75 GHz, respectively. According to the multi-beam interferences theory of FPC, the side-mode suppression rate of FPC schemes is in good agreement with our own theoretical results from 27 dB of a single FPC to 43 dB of paired FPCs. To maintain long-term stable operation and determine the absolute frequency mode number in the 23.75-GHz comb, the Pound–Drever–Hall (PDH) locking technology is utilized. Such stable tens GHz frequency combs have important applications in calibrating astronomical spectrographs with high resolution.

  12. Frequency Characteristics of Double-Walled Carbon Nanotube Resonator with Different Length

    Directory of Open Access Journals (Sweden)

    Jun-Ha LEE

    2016-05-01

    Full Text Available In this paper, we have conducted classical molecular dynamics simulations for DWCNTs of various wall lengths to investigate their use as ultrahigh frequency nano-mechanical resonators. We sought to determine the variations in the frequency of these resonators according to changes in the DWCNT wall lengths. For a double-walled carbon nanotube resonator with a shorter inner nanotube, the shorter inner nanotube can be considered to be a flexible core, and thus, the length influences the fundamental frequency. In this paper, we analyze the variation in frequency of ultra-high frequency nano-mechnical resonators constructed from DWCNTs with different wall lengths.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12951

  13. Generation of 3.5W high efficiency blue-violet laser by intracavity frequency-doubling of an all-solid-state tunable Ti:sapphire laser.

    Science.gov (United States)

    Ding, X; Wang, R; Zhang, H; Wen, W Q; Huang, L; Wang, P; Yao, J Q; Yu, X Y; Li, Z

    2008-03-31

    In this paper, we report a high power, high efficiency blue-violet laser obtained by intracavity frequency-doubling of an all-solid-state Q-switched tunable Ti:sapphire laser, which was pumped by a 532 nm intracavity frequency-doubled Nd:YAG laser. A beta-BaB2O4 (BBO) crystal was used for frequency-doubling of the Ti:sapphire laser and a V-shape folded three-mirror cavity was optimized to obtain high power high efficiency second harmonic generation (SHG). At an incident pump power of 22 W, the tunable output from 355 nm to 475 nm was achieved, involving the maximum average output of 3.5 W at 400 nm with an optical conversion efficiency of 16% from the 532 nm pump laser to the blue-violet output. The beam quality factor M(2) was measured to be Mx(2)=2.15, My(2)=2.38 for characterizing the tunable blue laser.

  14. Generation of 3.5W high efficiency blue-violet laser by intracavity frequency-doubling of an all-solid-state tunable Ti:sapphire laser.

    Science.gov (United States)

    Ding, X; Wang, R; Zhang, H; Wen, W Q; Huang, L; Wang, P; Yao, J Q; Yu, X Y; Li, Z

    2008-03-31

    In this paper, we report a high power, high efficiency blue-violet laser obtained by intracavity frequency-doubling of an all-solid-state Q-switched tunable Ti:sapphire laser, which was pumped by a 532 nm intracavity frequency-doubled Nd:YAG laser. A beta-BaB2O4 (BBO) crystal was used for frequency-doubling of the Ti:sapphire laser and a V-shape folded three-mirror cavity was optimized to obtain high power high efficiency second harmonic generation (SHG). At an incident pump power of 22 W, the tunable output from 355 nm to 475 nm was achieved, involving the maximum average output of 3.5 W at 400 nm with an optical conversion efficiency of 16% from the 532 nm pump laser to the blue-violet output. The beam quality factor M(2) was measured to be Mx(2)=2.15, My(2)=2.38 for characterizing the tunable blue laser. PMID:18542555

  15. Theoretical estimates of maximum fields in superconducting resonant radio frequency cavities: Stability theory, disorder, and laminates

    CERN Document Server

    Liarte, Danilo B; Transtrum, Mark K; Catelani, Gianluigi; Liepe, Matthias; Sethna, James P

    2016-01-01

    We review our work on theoretical limits to the performance of superconductors in high magnetic fields parallel to their surfaces. These limits are of key relevance to current and future accelerating cavities, especially those made of new higher-$T_c$ materials such as Nb$_3$Sn, NbN, and MgB$_2$. We summarize our calculations of the so-called superheating field $H_{\\mathrm{sh}}$, beyond which flux will spontaneously penetrate even a perfect superconducting surface and ruin the performance. We briefly discuss experimental measurements of the superheating field, comparing to our estimates. We explore the effects of materials anisotropy and disorder. Will we need to control surface orientation in the layered compound MgB$_2$? Can we estimate theoretically whether dirt and defects make these new materials fundamentally more challenging to optimize than niobium? Finally, we discuss and analyze recent proposals to use thin superconducting layers or laminates to enhance the performance of superconducting cavities. T...

  16. Flow coherent structures and frequency signature: application of the dynamic modes decomposition to open cavity flow

    Energy Technology Data Exchange (ETDEWEB)

    Lusseyran, F; Gueniat, F; Basley, J; Douay, C L; Pastur, L R; Faure, T M [LIMSI-CNRS BP 133, F-91403 Orsay Cedex (France); Schmid, P J [LadHyX, Ecole Polytechnique, F-91128 Palaiseau (France)

    2011-12-22

    The dynamic dimension of an impinging flow may be significantly reduced by its boundary conditions and self-sustained oscillations they induce. The spectral signature is associated with remarkable spatial coherent structures. Dynamic modes decomposition (DMD) makes it possible to directly extract the dynamical properties of a non-linearly saturated flow. We apply DMD to highlight the spectral contribution of the longitudinal and transverse structures of an experimental open-cavity flow.

  17. Analysis of Nb3Sn surface layers for superconducting radio frequency cavity applications

    Science.gov (United States)

    Becker, Chaoyue; Posen, Sam; Groll, Nickolas; Cook, Russell; Schlepütz, Christian M.; Hall, Daniel Leslie; Liepe, Matthias; Pellin, Michael; Zasadzinski, John; Proslier, Thomas

    2015-02-01

    We present an analysis of Nb3Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb3Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (Tc) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ˜2 μm thick Nb3Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb3Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low Tc regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb3Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  18. Analysis of Nb{sub 3}Sn surface layers for superconducting radio frequency cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Chaoyue [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Posen, Sam; Hall, Daniel Leslie [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Groll, Nickolas; Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Cook, Russell [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Schlepütz, Christian M. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liepe, Matthias [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States); Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Pellin, Michael [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zasadzinski, John [Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2015-02-23

    We present an analysis of Nb{sub 3}Sn surface layers grown on a bulk Niobium (Nb) coupon prepared at the same time and by the same vapor diffusion process used to make Nb{sub 3}Sn coatings on 1.3 GHz Nb cavities. Tunneling spectroscopy reveals a well-developed, homogeneous superconducting density of states at the surface with a gap value distribution centered around 2.7 ± 0.4 meV and superconducting critical temperatures (T{sub c}) up to 16.3 K. Scanning transmission electron microscopy performed on cross sections of the sample's surface region shows an ∼2 μm thick Nb{sub 3}Sn surface layer. The elemental composition map exhibits a Nb:Sn ratio of 3:1 and reveals the presence of buried sub-stoichiometric regions that have a ratio of 5:1. Synchrotron x-ray diffraction experiments indicate a polycrystalline Nb{sub 3}Sn film and confirm the presence of Nb rich regions that occupy about a third of the coating volume. These low T{sub c} regions could play an important role in the dissipation mechanisms occurring during RF tests of Nb{sub 3}Sn-coated Nb cavities and open the way for further improving a very promising alternative to pure Nb cavities for particle accelerators.

  19. Treatment of nevus of OTA by Q-switched, frequency doubled, ND: Yag laser

    Directory of Open Access Journals (Sweden)

    National Skin and Hair Care Centre

    2002-01-01

    Full Text Available Nevus of Ota is a dermal melanocytic nevus for which hitherto no effective therapy was available. Lasers have been successfully tried for ablation. But there is no Indian experience till date. Q- Switched, Frequency Doubled, Nd: YAG Laser was installed at our centre an year ago. The first operated case, which has shown near complete pigment dilution, is being presented. The patient underwent three treatments with a minimum of 2 months between sessions. Pre and post therapy photographs were taken and side effects documented. The patient has shown near complete pigment dilution after 3 treatments. Q-Switched, Frequency Doubled, Nd: YAG Laser is effective in treating Nevus of Ota in the Indian skin types. There are no complications noticed till date in our experience.

  20. Frequency Response Calculations of Input Characteristics of Cavity-Backed Aperture Antennas Using AWE with Hybrid FEM/MoM Technique

    Science.gov (United States)

    Reddy, C. J.; Deshpande, M. D.

    1997-01-01

    Application of Asymptotic Waveform Evaluation (AWE) is presented in conjunction with a hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique to calculate the input characteristics of cavity-backed aperture antennas over a frequency range. The hybrid FEM/MoM technique is used to form an integro-partial-differential equation to compute the electric field distribution of the cavity-backed aperture antenna. The electric field, thus obtained, is expanded in a Taylor series around the frequency of interest. The coefficients of 'Taylor series (called 'moments') are obtained using the frequency derivatives of the integro-partial-differential Equation formed by the hybrid FEM/MoM technique. Using the moments, the electric field in the cavity is obtained over a frequency range. Using the electric field at different frequencies, the input characteristics of the antenna are obtained over a wide frequency band. Numerical results for an open coaxial line, probe fed cavity, and cavity-backed microstrip patch antennas are presented. Good agreement between AWE and the exact solution over the frequency range is observed.

  1. Frequency doubled high-power disk lasers in pulsed and continuous-wave operation

    Science.gov (United States)

    Weiler, Sascha; Hangst, Alexander; Stolzenburg, Christian; Zawischa, Ivo; Sutter, Dirk; Killi, Alexander; Kalfhues, Steffen; Kriegshaeuser, Uwe; Holzer, Marco; Havrilla, David

    2012-03-01

    The disk laser with multi-kW output power in infrared cw operation is widely used in today's manufacturing, primarily in the automotive industry. The disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency and high reliability with low investment and operating costs. Additionally, the disk laser is ideally suited for frequency conversion due to its polarized output with negligible depolarization losses. Laser light in the green spectral range (~515 nm) can be created with a nonlinear crystal. Pulsed disk lasers with green output of well above 50 W (extracavity doubling) in the ps regime and several hundreds of Watts in the ns regime with intracavity doubling are already commercially available whereas intracavity doubled disk lasers in continuous wave operation with greater than 250 W output are in test phase. In both operating modes (pulsed and cw) the frequency doubled disk laser offers advantages in existing and new applications. Copper welding for example is said to show much higher process reliability with green laser light due to its higher absorption in comparison to the infrared. This improvement has the potential to be very beneficial for the automotive industry's move to electrical vehicles which requires reliable high-volume welding of copper as a major task for electro motors, batteries, etc.

  2. Cryogenic Testing of High-Velocity Spoke Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, Christopher S. [Old Dominion University; Delayen, Jean R. [Old Dominion University; Park, HyeKyoung [JLAB

    2014-12-01

    Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0= 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

  3. A Micro Blue-violet Laser by Frequency Doubling of Semiconductor Laser

    Institute of Scientific and Technical Information of China (English)

    JIN Jie1; GUO Shuguang; LU Fuyun; ZHANG Guangyin; JIAO Qiang; FANG Xiaojun; YAO Jianquan

    2001-01-01

    In this paper, a micro blue-violet laser by frequency doubling of a semiconductor laser with a new nonlinear organometallic complex cadmium mercury thiocyanate crystal (CMTC) is reported. At room temperature, the blue-violet laser output of 11.8 mW at 404 nm and the conversion4efficiency of the second harmonic generation (SHG) of 0. 60% were obtained with a 1. 98 W, 808 nm semiconductor laser and a 4 mm crystal.

  4. OH detection by absorption of frequency-doubled diode laser radiation at 308nm

    OpenAIRE

    Barry, Hugh R.; Bakowski, Ben; Corner, Laura; Freegarde, Tim; Hawkins, Oliver T. W.; Hancock, Gus; Jacobs, Robert M. J.; Peverall, Robert; Ritchie, Grant A.D.

    2000-01-01

    Radiation at 308 nm has been obtained by frequency doubling the output of a commercial diode laser cooled to 165 K. A single pass through a crystal of LiIO3 converted 1 mW of 616 nm radiation to 50 pW of UV, and this was used to detect the OH radical in absorption in a flow tube. Possible extensions of the method for detection of OH in the atmosphere are discussed.

  5. Advances in optically pumped semiconductor lasers for blue emission under frequency doubling

    Science.gov (United States)

    Bai, Yanbo; Wisdom, Jeffrey; Charles, John; Hyland, Patrick; Scholz, Christian; Xu, Zuntu; Lin, Yong; Weiss, Eli; Chilla, Juan; Lepert, Arnaud

    2016-03-01

    Optically pumped semiconductor lasers (OPSL) offer the advantage of excellent beam quality, wavelength agility, and high power scaling capability. In this talk we will present our recent progress of high-power, 920nm OPSLs frequency doubled to 460nm for lightshow applications. Fundamental challenges and mitigations are revealed through electrical, optical, thermal, and mechanical modeling. Results also include beam quality enhancement in addressing the competition from diode lasers.

  6. High-power continuous-wave frequency-doubling in KTiOAsO4.

    Science.gov (United States)

    Zeil, Peter; Zukauskas, Andrius; Tjörnhammar, Staffan; Canalias, Carlota; Pasiskevicius, Valdas; Laurell, Fredrik

    2013-12-16

    High-power continuous-wave generation at 533 nm is demonstrated in bulk periodically poled KTiOAsO(4) (KTA) by single-pass frequency doubling of a VBG-locked Yb-doped fiber laser. Absorption characteristic and second harmonic generation (SHG) performance of different KTA samples are studied and compared. The best performing sample catered for 25%-efficient SHG of 13.6 W green light with high spatial beam quality M(2) <1.2. PMID:24514622

  7. Dynamics of two coupled chaotic multimode Nd:YAG lasers with intracavity frequency doubling crystal

    Indian Academy of Sciences (India)

    Thomas Kuruvilla; V M Nandakumaran

    2000-03-01

    The effect of coupling two chaotic Nd:YAG lasers with intracavity KTP crystal for frequency doubling is numerically studied for the case of the laser operating in three longitudinal modes. It is seen that the system goes from chaotic to periodic and then to steady state as the coupling constant is increased. The intensity time series and phase diagrams are drawn and the Lyapunov characteristic exponent is calculated to characterize the chaotic and periodic regions.

  8. Evaluation of magnocellular pathway abnormalities in schizophrenia: a frequency doubling technology study and clinical implications

    Directory of Open Access Journals (Sweden)

    Fabiana Benites Vaz de Lima

    2013-04-01

    Full Text Available BACKGROUND: Visual processing deficits have been reported for patients with schizophrenia. Previous studies demonstrated differences in early-stage processing of schizophrenics, although the nature, extent, and localization of the disturbance are unknown. The magnocellular and parvocellular visual pathways are associated with transient and sustained channels, but their respective contributions to schizophrenia-related visual deficits remains controversial. PURPOSE: The aim of this study was to evaluate magnocellular dysfunction in schizophrenia using frequency doubling technology. METHODS: Thirty-one patients with schizophrenia and 34 healthy volunteers were examined. Frequency doubling technology testing was performed in one session, consisting of a 15-minute screening strategy followed by the C-20 program for frequency doubling technology. RESULTS: Schizophrenic patients showed lower global mean sensitivity (30,97 ± 2,25 dB compared with controls (32,17 ± 3,08 dB, p<0.009. Although there was no difference in the delta sensitivity of hemispheres, there was a difference in sensitivity analysis of the fibers crossing the optic chiasm, with lower mean sensitivity in the patient group (28,80 dB versus controls (30,66 dB. The difference was higher in fibers that do not cross the optic chiasm, with lower mean sensitivity in patients (27,61 dB versus controls (30,26 dB, p<0.005. CONCLUSIONS: Our results suggest that there are differences between global sensitivity and fiber sensitivity measured by frequency doubling technology. The different sensitivity of fibers that do not cross the optic chiasm is consistent with most current etiological hypotheses for schizophrenia. The decreased sensitivity responses in the optic radiations may significantly contribute to research assessing early-stage visual processing deficits for patients with schizophrenia.

  9. Effects of fabricated error on transmission performance of double layer frequency selective surface configuration

    Institute of Scientific and Technical Information of China (English)

    HE Bin; SUN Lian-chun

    2005-01-01

    Based on the experimental results, in which the fabricated error of the double layer frequency selective surface (FSS) leads to the transmission loss and the resonant frequency leaves away the design resonant frequency, the inter-layer separation distance (ISD) and the unit cell aligning error (UAE) were used as main variables to study the transmission performance attenuation of the double layer FSS configuration. The numerical analysis model for ISD and UAE was established and also was used to simulate the ring unit cell FSS transmission performance by the finite element and periodic moment methods. The double layer ring aperture FSS configuration designed was used as the numerical model. As a result of the numerical analysis, it is shown that both ISD and UAE produce insertion transmission loss (ITL) and insertion phase distortion (IPD) directly. Furthermore, ISD results in more loss of the amplitude of the transmitted signal for the FSS than UAE. It is significant for the designer of the multiplayer FSS to assign the fabricated error of the FSS dielectric layers. The UAE introduces the insertion phase variation badly.

  10. Absolute distance measurement by multi-heterodyne interferometry using a frequency comb and a cavity-stabilized tunable laser.

    Science.gov (United States)

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Balling, Petr; Qu, Xinghua

    2016-05-20

    In this paper, we develop a multi-heterodyne system capable of absolute distance measurement using a frequency comb and a tunable diode laser locked to a Fabry-Perot cavity. In a series of subsequent measurements, numerous beat components can be obtained by downconverting the optical frequency into the RF region with multi-heterodyne interferometry. The distances can be measured via the mode phases with a series of synthetic wavelengths. The comparison with the reference interferometer shows an agreement within 1.5 μm for the averages of five measurements and 2.5 μm for the single measurement, which is at the 10-8 relative precision level. PMID:27411152

  11. Topographic power spectral density study of the effect of surface treatment processes on niobium for superconducting radio frequency accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Charles Reece, Hui Tian, Michael Kelley, Chen Xu

    2012-04-01

    Microroughness is viewed as a critical issue for attaining optimum performance of superconducting radio frequency accelerator cavities. The principal surface smoothing methods are buffered chemical polish (BCP) and electropolish (EP). The resulting topography is characterized by atomic force microscopy (AFM). The power spectral density (PSD) of AFM data provides a more thorough description of the topography than a single-value roughness measurement. In this work, one dimensional average PSD functions derived from topography of BCP and EP with different controlled starting conditions and durations have been fitted with a combination of power law, K correlation, and shifted Gaussian models to extract characteristic parameters at different spatial harmonic scales. While the simplest characterizations of these data are not new, the systematic tracking of scale-specific roughness as a function of processing is new and offers feedback for tighter process prescriptions more knowledgably targeted at beneficial niobium topography for superconducting radio frequency applications.

  12. Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments

    CERN Document Server

    Przygoda, K

    2011-01-01

    This dissertation covers the recent research and development (R&D) activities of control systems for the fast frequency tuners of TESLA cavities and predicts the implications foreseen for large scale machines such as the FLASH and the planned XFEL. In particular, the framework of the presented activities is the effort toward the: 1. R&D of the driving circuit, 2. R&D of the control algorithm, 3. R&D of the control system. The main result of these activities is the permanent installation of the target piezo control system and its commissioning for 40 cavities divided into 5 accelerating modules at the DESY FLASH facility. The author’s contribution was the study of possible designs of high-voltage, high-current power amplifiers, used for driving the fast frequency tuners, shows that several parameters of such a device needs to be considered. The most important parameter is the input and output power estimation. This arises from the fact that the estimation is the most crucial issue for both po...

  13. A quadrature frequency converter in a feedback loop of high frequency cavities in the Proton Synchrotron at CERN.

    CERN Document Server

    Truszczynski, T

    This thesis presents the author’s work during the internship at the European Laboratory for Particle Physics (CERN). The quadrature frequency converter is one of the modules that has been developed to upgrade the Proton Synchrotron RF system. Basic information about accelerators, fundamentals of IQ signal representation, mixing and phase shifting techniques are introduced. The development process of the converter is presented with the design details and measurements of the prototype board.

  14. Development of a cryogenic radiation detector for mapping radio frequency superconducting cavity field emissions

    Energy Technology Data Exchange (ETDEWEB)

    Danny Dotson; John Mammosser

    2005-05-01

    Field emissions in a super conducting helium cooled RF cavity and the production of radiation (mostly X-Rays) have been measured externally on cryomodules at Jefferson Lab since 1991. External measurements are limited to radiation energies above 100 keV due to shielding of the stainless steel cryogenic body. To measure the onset of and to map field emissions from a superconducting cavity requires the detecting instrument be inside the shield and within the liquid Helium. Two possible measurement systems are undergoing testing at JLab. A CsI detector array set on photodiodes and an X-Ray film camera with a fixed aperture. Several devices were tested in the cell with liquid Helium without success. The lone survivor, a CsI array, worked but saturated at high power levels due to backscatter. The array was encased in a lead shield with a slit opening set to measure the radiation emitted directly from the cell eliminating a large portion of the backscatter. This is a work in progress and te sting should be complete before the PAC 05. The second system being tested is passive. It is a shielded box with an aperture to expose radiation diagnostic film located inside to direct radiation from the cell. Developing a technique for mapping field emissions in cryogenic cells will assist scientists and engineers in pinpointing any surface imperfections for examination.

  15. The relationship between temporal phase discrimination ability and the frequency doubling illusion.

    Science.gov (United States)

    Vallam, Kunjam; Metha, Andrew B

    2007-12-20

    The frequency doubling illusion (FDI) occurs when a low spatial frequency sinusoidal grating is modulated at high temporal frequencies--its apparent spatial frequency increases. A recent study suggests that this illusion is perceived due to a frequency-dependent loss of temporal phase encoding ability. We sought to elucidate the relationship between temporal phase encoding and the FDI by exploring the spatiotemporal characteristics of temporal phase discrimination (TPD) thresholds using a novel stimulus comprising three grating patches presented simultaneously in a triangular pattern. A reference grating was presented superiorly, and six degrees below two gratings (one a copy of the reference) were each randomly presented in one of two fixed positions. The odd grating had abutting regions of spatial half-cycles with alternate half-cycles locked in temporal phase. The temporal phase difference between adjoining half-cycles was varied between 0 degrees and 180 degrees via QUEST staircase--subjects had to identify which lower stimulus appeared different from the reference grating. TPD thresholds were measured for 0.25, 0.50, and 2.20 cpd stimulus at six temporal frequencies (1 to 28 Hz) at 2x, 4x, and 8x orientation identification contrast thresholds. For all subjects, thresholds were variable at low contrasts. At higher contrasts, TPD thresholds increase for 0.25 and 0.50 cpd gratings with increasing flicker rate. These data support the idea that frequency-dependent loss of temporal phase encoding ability could possibly underlie the FDI.

  16. Research and data pro cessing of double lo cked cavity ringdown absorption sp ectroscopy%双重频率锁定的腔衰荡吸收光谱技术及信号处理∗

    Institute of Scientific and Technical Information of China (English)

    贾梦源; 肖连团; 贾锁堂; 赵刚; 侯佳佳; 谭巍; 邱晓东; 马维光; 张雷; 董磊; 尹王保

    2016-01-01

    A continuous wave cavity ringdown spectroscopy based on a double-locking loop is proposed to improve the short-coming of low acquisition rate of concentration in traditional scheme. A small portion of laser is separated to pass through a C2H2 reference cell, used to lock the laser frequency to the ν1+ν3 band P(9)e absorption line of C2H2 at 6534.3634 cm−1 by the 1st harmonic demodulation of the frequency modulation spectroscopy. The remaining portion is incident on a high finesses cavity to observe the ringdown events. Meanwhile, the reflected light of cavity is used to extract the error signal to lock the laser based on the PDH frequency locking technique. As a consequence, the frequency drift of the laser and the jitter of the cavity length are improved, therefore a more relatively accuracy result is expected. The laser light is dual frequency modulated by a fiber coupled electro optic modulator (FEOM)in the above system. In order to optimize, to some extent, the asymmetry of the error signal caused by the residual amplitude modulation due to the inconsistency of the laser polarization direction with the extraordinary axis of the FEOM, the demodulation phase is adjusted carefully until the error signal is smoothed up and close to symmetry. Then, the effect of locking loop is examined. The frequency of laser, based on the measurement by a wavelength meter, is more stable and the relative frequency discrimination between the laser and the longitudinal mode of cavity is about 9.8 kHz. In addition, the PDH locking, ensuring the efficient coupling of the laser with the cavity, can gain a high acquisition rate of the concentration information. In order to obtain a complete ringdown event, the frequency of square wave to the fiber coupled acoustic optical modulator (FAOM) is limited to 30 kHz with the duty cycle of 85%, which is determined by the ringdown time and re-lock time. However, there exists a relatively large random noise in a series of ringdown time

  17. Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Roy Crooks, Ph.D., P.E.

    2009-10-31

    The positron and electron linacs of the International Linear Collider (ILC) will require over 14,000, nine-cell, one meter length, superconducting radio frequency (SRF) cavities [ILC Reference Design Report, 2007]. Manufacturing on this scale will benefit from more efficient fabrication methods. The current methods of fabricating SRF cavities involve deep drawing of the halves of each of the elliptical cells and joining them by high-vacuum, electron beam welding, with at least 19 circumferential welds per cavity. The welding is costly and has undesirable effects on the cavity surfaces, including grain-scale surface roughening at the weld seams. Hydroforming of seamless tubes avoids welding, but hydroforming of coarse-grained seamless tubes results in strain-induced surface roughening. Surface roughness limits accelerating fields, because asperities prematurely exceed the critical magnetic field and become normal conducting. This project explored the technical and economic feasibility of an improved processing method for seamless tubes for hydroforming. Severe deformation of bulk material was first used to produce a fine structure, followed by extrusion and flow-forming methods of tube making. Extrusion of the randomly oriented, fine-grained bulk material proceeded under largely steady-state conditions, and resulted in a uniform structure, which was found to be finer and more crystallographically random than standard (high purity) RRR niobium sheet metal. A 165 mm diameter billet of RRR grade niobium was processed into five, 150 mm I.D. tubes, each over 1.8 m in length, to meet the dimensions used by the DESY ILC hydroforming machine. Mechanical properties met specifications. Costs of prototype tube production were approximately twice the price of RRR niobium sheet, and are expected to be comparable with economies of scale. Hydroforming and superconducting testing will be pursued in subsequent collaborations with DESY and Fermilab. SRF Cavities are used to construct

  18. A new three-dimensional shape measurement method based on double-frequency fringes

    Science.gov (United States)

    Li, Biao; Yang, Jie; Wu, Haitao; Fu, Yanjun

    2015-10-01

    Fringe projection profilometry (FPP) is a rapidly developing technique which is widely used for industrial manufacture, heritage conservation, and medicine etc. because of its high speed, high precision, non-contact operation, full-field acquisition, and easy information processing. Among the various FFP methods, the squared binary defocused projection method (SBM) has been promptly expanding with several advantages: (1) high projection speed because of 1-bit grayscale fringe; (2) eliminating nonlinear gamma of the projector for the defocusing effect. Nevertheless, the method is not trouble-free. When the fringe stripe is wide, it brings down the fringe contrast and is difficult to control the defocused degree, resulting in a low measurement accuracy. In order to further improve high-speed and high-precision three-dimensional shape measurement, this paper presents a new three-dimensional shape measurement method based on double-frequency fringes projection. This new method needs to project two sets of 1-bit grayscale fringe patterns (low-frequency fringe and high-frequency fringe) onto the object surface under slightly defocused projection mode. The method has the following advantages: (1) high projection speed because of 1-bit grayscale fringe; (2) high measurement precision for selectively removing undesired harmonics. Low-frequency fringe is produced by error-diffusion dithering (Dithering) technique and high-frequency fringe is generated by optimal pulse-width modulation (OPWM) technique. The two kinds of fringe patterns have each superiorities and flaws. The low-frequency fringe has a low measurement accuracy, but the continue phase can be easily retrieved. However, the property of high-frequency fringe and low-frequency fringe is the opposite. The general idea of this method proposed is as follows: Because the both fringes test the same object, the height is the same. The low-frequency fringe can be used to assist the high frequency fringe to retrieve

  19. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    Science.gov (United States)

    Wen, Xin; Han, Yashuai; Wang, Junmin

    2016-04-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power to 111 mW of 397.5 nm UV output. For LBO crystal, with 1.34 W of mode-matched 795 nm power, 770 mW of 397.5 nm UV output is achieved, implying a doubling efficiency of 57.4%. For BiBO crystal, with 323 mW of mode-matched 795 nm power, 116 mW of 397.5 nm UV output is achieved, leading to a doubling efficiency of 35.9%. The generated UV radiation has potential applications in the fields of quantum physics.

  20. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Nanoscale defect structure within the magnetic penetration depth of ~100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120°C baking. Furthermore, we demonstrate that adding 800°C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120°C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120°C bake

  1. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Trenikhina, Y., E-mail: yuliatr@fnal.gov [Physics Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Romanenko, A., E-mail: aroman@fnal.gov [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Kwon, J.; Zuo, J.-M. [Materials Science and Engineering Department, University of Illinois, Urbana, Illinois 61801 (United States); Zasadzinski, J. F. [Physics Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2015-04-21

    Nanoscale defect structure within the magnetic penetration depth of ∼100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120 °C baking. Furthermore, we demonstrate that adding 800 °C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120 °C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120 °C bake.

  2. Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser

    OpenAIRE

    Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J.; Tang, Shuo

    2016-01-01

    We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 78...

  3. Modulation of a double-line frequency up-conversion process in cesium vapor

    Science.gov (United States)

    Gai, Baodong; Cao, Rui; Xia, Xusheng; Hu, Shu; Liu, Jinbo; Guo, Jingwei; Tan, Yannan; Liu, Wanfa; Jin, Yuqi; Sang, Fengting

    2016-06-01

    We have observed frequency up-conversion in Cs vapor. The pulsed pumping laser beam of 767.2 nm was converted to simultaneous collinear ultraviolet and blue radiation of wavelengths 387.7 and 455.6 nm, respectively (double-line frequency up-conversion). We examined properties of this up-conversion such as energy efficiency and pulse widths. An infrared laser of ~2.4 μm was successful in modulating the laser beam of the frequency up-conversion. The modulation shifts the wavelength of the blue radiation and the intensities of both the blue and ultraviolet radiation. At nanosecond grade, such modulations are expected to have applications in near-infrared up-conversion and optical communications.

  4. Efficient frequency doubler of 1560 nm laser based on a semi-monolithic resonant cavity with a PPKTP crystal

    Science.gov (United States)

    Wang, Junmin; Zhang, Kong; Ge, Yulong; Guo, Shanlong

    2016-06-01

    We have demonstrated 1.61 W of 780 nm single-frequency continuous-wave laser output with a semi-monolithic periodically poled potassium titanyl phosphate (PPKTP) crystal doubler pumped by a 2-W erbium-doped fiber amplifier boosted 1560 nm diode laser. The measured maximum doubling efficiency is 77%, and the practical value should be 80% when taking into account the fundamental-wave mode matching efficiency. The measured beam quality factor of 780 nm output, M2, is better than 1.04. Typical root-mean-square fluctuation of 780 nm output is less than 0.5% in 30 minutes. This compact frequency doubler has good mechanical stability, and can be employed for many applications, such as laser cooling and trapping, atomic coherent control, atomic interferometer, and quantum frequency standard with rubidium atoms.

  5. Compact deep UV laser system at 222.5 nm by single-pass frequency doubling of high-power GaN diode laser emission

    Science.gov (United States)

    Ruhnke, Norman; Müller, André; Eppich, Bernd; Güther, Reiner; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2016-03-01

    Deep ultraviolet (DUV) lasers emitting below 300 nm are of great interest for many applications, for instance in medical diagnostics or for detecting biological agents. Established DUV lasers, e.g. gas lasers or frequency quadrupled solid-state lasers, are relatively bulky and have high power consumptions. A compact and reliable laser diode based system emitting in the DUV could help to address applications in environments where a portable and robust light source with low power consumption is needed. In this work, a compact DUV laser system based on single-pass frequency doubling of highpower GaN diode laser emission is presented. A commercially available high-power GaN laser diode from OSRAM Opto Semiconductors serves as a pump source. The laser diode is spectrally stabilized in an external cavity diode laser (ECDL) setup in Littrow configuration. The ECDL system reaches a maximum optical output power of 700 mW, maintaining narrowband emission below 60 pm (FWHM) at 445 nm over the entire operating range. By direct single pass frequency doubling in a BBO crystal with a length of 7.5 mm a maximum DUV output power of 16 μW at a wavelength of 222.5 nm is generated. The presented concept enables compact and efficient diode laser based light sources emitting in the DUV spectral range that are potentially suitable for in situ applications where a small footprint and low power consumption is essential.

  6. 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.

  7. A compact gas single-mode radio-frequency excited laser with a hybrid unstable and waveguide cavity

    International Nuclear Information System (INIS)

    In recent years we have seen a steady increase in the use of transverse radio-frequency (RF) gas discharges for excitation of carbon dioxide (CO2) lasers. However, RF excitation can be realized in carbon oxide (CO) and xenon (Xe) lasers. We attempt to construct a RF laser, which can work in broad spectral range of radiation. The design of this laser is based on the use of unstable telescopic cavity with the radiation spreading both in the free space and inside the waveguide. Employed discharge structure is formed by two parallel identical electrodes 30 x 230 mm in area and allocated at 2.5 mm distance from one another, and it has a gap, which is not confined limited by side walls. This ensures convective gas exchange between the reserve and active zones. This construction allows to get a high output power of generation with lasers having small dimensions, provides an opportunity to use single-mode generation for the basic hybrid mode; the latter is a combination of the lowest mode of gap waveguide and the lowest mode of unstable cavity

  8. Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

    CERN Document Server

    Kubo, Takayuki

    2014-01-01

    The field limit of superconducting radio-frequency cavity made of type II superconductor with a large Ginzburg-Landau parameter is studied with taking effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for ideal flat surface and a suppression factor that contains effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors are derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by the electropolishing is evaluated by using results of surface topographic study. The estimat...

  9. 90.4-W all-fiber single-frequency polarization-maintained 1083-nm MOPA laser employing ring-cavity single-frequency seed oscillator

    Institute of Scientific and Technical Information of China (English)

    Jiangming Xu; Rongtao Su; Hu Xiao; Pu Zhou; Jing Hou

    2012-01-01

    A high-power all-fiber single-frequency polarization-maintained (PM) laser operating at 1083 nm is demonstrated using a master oscillator power amplifier (MOPA) structure. The seed source of this MOPA laser system is an in-house-built ring-cavity fiber oscillator. Four-stage amplification configuration is employed, in which the maximal output power of the main amplifier is 90.4 W, corresponding to a conversion efficiency of 72.5%. The polarization extinction ratio of the output light is 13 dB. The amplified spontaneous emission is suppressed by a factor of over 25 dB, and no stimulated Brillouin scattering effect is observed when a large-mode-area and high absorption coefficient PM gain fiber is employed.%A high-power all-fiber single-frequency polarization-maintained (PM) laser operating at 1083 nm is demonstrated using a master oscillator power amplifier (MOPA) structure.The seed source of this MOPA laser system is an in-house-built ring-cavity fiber oscillator.Four-stage amplification configuration is employed,in which the maximal output power of the main amplifier is 90.4 W,corresponding to a conversion efficiency of 72.5%.The polarization extinction ratio of the output light is 13 dB.The amplified spontaneous emission is suppressed by a factor of over 25 dB,and no stimulated Brillouin scattering effect is observed when a large-mode-area and high absorption coefficient PM gain fiber is employed.

  10. Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

    Energy Technology Data Exchange (ETDEWEB)

    Tian Hui [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Kelley, Michael J. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States)]. E-mail: mkelley@jlab.org; Wang Shancai [Department of Physics, Boston University (United States); Plucinski, Lukasz [Department of Physics, Boston University (United States); Smith, Kevin E. [Department of Physics, Boston University (United States); Nowell, Matthew M. [EDAX TSL (United States)

    2006-11-30

    The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is {+-}30% and that of the surface composition is {+-}5%.

  11. Frequency doubled telecom fiber laser for a cold atom interferometer using optical lattices

    CERN Document Server

    Theron, Fabien; Dieu, Emily; Zahzam, Nassim; Cadoret, Malo; Zahzam, Nassim; Bresson, Alexandre

    2016-01-01

    A compact and robust laser system, based on a frequency-doubled telecom laser, providing all the lasers needed for a rubidium cold atom interferometer using optical lattices is presented. Thanks to an optical switch at 1.5 \\mu m and a dual-wavelength second harmonic generation system, only one laser amplifier is needed for all the laser system. Our system delivers at 780 nm a power of 900 mW with a detuning of 110 GHz for the optical lattice and a power of 650 mW with an adjustable detuning between 0 and -1 GHz for the laser cooling, the detection and the Raman transitions.

  12. Temporal structure of double plasma frequency emission of thin beam-heated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Postupaev, V. V.; Ivanov, I. A.; Arzhannikov, A. V.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation); Burdakov, A. V.; Polosatkin, S. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Avenue, 630092 Novosibirsk (Russian Federation); Sklyarov, V. F.; Gavrilenko, D. Ye.; Kandaurov, I. V.; Kurkuchekov, V. V.; Mekler, K. I.; Popov, S. S.; Rovenskikh, A. F.; Sudnikov, A. V.; Sulyaev, Yu. S.; Trunev, Yu. A. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Kasatov, A. A. [Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation)

    2013-09-15

    In the work presented here dynamics of spiky microwave emission of a beam-heated plasma near the double plasma frequency in ∼100 GHz band was studied. The plasma is heated by 80 keV, ∼2 MW, sub-ms electron beam that is injected into the multiple-mirror trap GOL-3. The beam-heated plasma diameter is of the order of the emitted wavelength. Modulation of individual emission spikes in the microwave radiation is found. The radiation dynamics observed can be attributed to a small number of compact emitting zones that are periodically distorted.

  13. 100W single mode single polarization picosecond ytterbium doped fibre MOPA frequency doubled to 530nm

    OpenAIRE

    Chen, K. K.; Alam, S. -U.; Hayes, J R; Lin, D.; Malinowski, A.; Richardson, D J

    2009-01-01

    High average power laser sources operating in the picosecond (ps) regime are useful for a wide range of applications including frequency-doubling and pumping of OPOs. Gain switching (GS) of laser diodes provides a practical and low cost method to generate ps pulses at GHz repetition rates and mW average power levels. Such devices represent excellent seeds for high power fiber MOPAs allowing power scaling to the 100W regime and we recently reported average powers in excess of 300W from a 1060n...

  14. Application of Model Based Parameter Estimation for Fast Frequency Response Calculations of Input Characteristics of Cavity-Backed Aperture Antennas Using Hybrid FEM/MoM Technique

    Science.gov (United States)

    Reddy C. J.

    1998-01-01

    Model Based Parameter Estimation (MBPE) is presented in conjunction with the hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique for fast computation of the input characteristics of cavity-backed aperture antennas over a frequency range. The hybrid FENI/MoM technique is used to form an integro-partial- differential equation to compute the electric field distribution of a cavity-backed aperture antenna. In MBPE, the electric field is expanded in a rational function of two polynomials. The coefficients of the rational function are obtained using the frequency derivatives of the integro-partial-differential equation formed by the hybrid FEM/ MoM technique. Using the rational function approximation, the electric field is obtained over a frequency range. Using the electric field at different frequencies, the input characteristics of the antenna are obtained over a wide frequency range. Numerical results for an open coaxial line, probe-fed coaxial cavity and cavity-backed microstrip patch antennas are presented. Good agreement between MBPE and the solutions over individual frequencies is observed.

  15. A superhigh-frequency optoelectromechanical system based on a slotted photonic crystal cavity

    CERN Document Server

    Sun, Xiankai; Poot, Menno; Xiong, Chi; Tang, Hong X

    2012-01-01

    We develop an all-integrated optoelectromechanical system that operates in the superhigh frequency band. This system is based on an ultrahigh-Q slotted photonic crystal (PhC) nanocavity formed by two PhC membranes, one of which is patterned with electrode and capacitively driven. The strong simultaneous electromechanical and optomechanical interactions yield efficient electrical excitation and sensitive optical transduction of the bulk acoustic modes of the PhC membrane. These modes are identified up to a frequency of 4.20 GHz, with their mechanical Q factors ranging from 240 to 1,730. Directly linking signals in microwave and optical domains, such optoelectromechanical systems will find applications in microwave photonics in addition to those that utilize the electromechanical and optomechanical interactions separately.

  16. Analysis of the resonance frequency shift in cylindrical cavities containing a sphere and its prediction based on the Boltzmann-Ehrenfest principle

    DEFF Research Database (Denmark)

    Orozco Santillán, Arturo; Cutanda Henriquez, Vicente

    2008-01-01

    levitation, has numerous applications in containerless study and processing of materials. Although it is possible to levitate a sample for long periods of time, instabilities can appear under certain conditions. One of the causes of oscillational instabilities is the change of the resonance frequency...... of the cavity due to the presence of the levitated object. The Boltzmann-Ehrenfest principle has been used to obtain an analytical expression for the resonance frequency shift in a cylindrical cavity produced by a small sphere, with kR

  17. Output Mode Simulation of Frequency Doubling External Resonant in PPLN%PPLN谐振倍频外腔输出模场的模拟研究

    Institute of Scientific and Technical Information of China (English)

    卢峰; 张蓉竹; 刘正颍; 孙年春

    2011-01-01

    To study the output mode distribution of the frequency doubling resonant in PPLN,the field distributions and beam quality M2 factor of the plano-concave resonator or dual-cavity were calculated and compared.The output fundamental modes of them with tilted Gaussian-reflectivity mirrors were simulated with Fourier transformation method and Fox-Li iterative method.The results show that the output fundamental mode of the frequency doubling external resonants is Gaussian distribution,and cavity length changes have less effect on the output beam quality.The output beam quality of the plano-concave resonator is M2=1.296,divergence angle θ=58.084μrad,and the Dual-cavity is M2=6.930,θ= 310.56μrad.The output beam quality of the plano-concave resonator is superior to the Dual-cavity.%为了探究PPLN外部谐振倍频腔的输出模式,从菲涅尔-基尔霍夫衍射积分公式出发,采用快速傅里叶变换法(FFT)和Fox-Li迭代法数值模拟高斯反射率圆形平凹倍频腔输出基模的场强分布、相位分布和光束质量M2因子,同时与圆形双凹倍频腔做了比较.计算结果表明,两类倍频谐振腔输出塞模均为高斯分布,腔长变化对两类倍频腔输出光束质量的影响较小.平凹倍频腔输出光束质量M2=1.296,远场发散角θ=58.084 μrad;而双凹倍频腔输出光束质量M2=6.930,θ=310.56 μrad.平凹倍频腔输出光束质量明显优于双凹倍频腔.

  18. 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.

  19. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    NARCIS (Netherlands)

    Ho, Jen-Hsuan; Berkhoff, A.P.

    2014-01-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of

  20. The Double Pulsar Eclipses I: Phenomenology and Multi-frequency Analysis

    CERN Document Server

    Breton, R P; McLaughlin, M A; Lyutikov, M; Kramer, M; Stairs, I H; Ransom, S M; Ferdman, R D; Camilo, F; Possenti, A

    2012-01-01

    The double pulsar PSR J0737-3039A/B displays short, 30 s eclipses that arise around conjunction when the radio waves emitted by pulsar A are absorbed as they propagate through the magnetosphere of its companion pulsar B. These eclipses offer a unique opportunity to probe directly the magnetospheric structure and the plasma properties of pulsar B. We have performed a comprehensive analysis of the eclipse phenomenology using multi-frequency radio observations obtained with the Green Bank Telescope. We have characterized the periodic flux modulations previously discovered at 820 MHz by McLaughlin et al., and investigated the radio frequency dependence of the duration and depth of the eclipses. Based on their weak radio frequency evolution, we conclude that the plasma in pulsar B's magnetosphere requires a large multiplicity factor (~ 10^5). We also found that, as expected, flux modulations are present at all radio frequencies in which eclipses can be detected. Their complex behavior is consistent with the confin...

  1. A Double Multi-Relaxation-Time Lattice Boltzmann Method for Simulation of Magneto Hydrodynamics Natural Convection of Nanofluid in a Square Cavity

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Rahmati

    2016-01-01

    Full Text Available In this work, for the first time, a double multi-relaxation-time lattice Boltzmann method (2-MRT-LBM is proposed to simulate MHD natural convection of nanofluid in a two-dimensional square cavity. The cavity is filled with TiO2-water nanofluid and is get under a uniform magnetic field at different angles ϕ with respect to horizontal plane. The proposed numerical scheme is solved the flow field and the temperature field using MRT-D2Q9 and MRT-D2Q5 lattice model, respectively. So, the main objective of this work is to show the effectiveness of this model to predict the effects of pertinent parameters such as the Rayleigh number (103 < Ra < 107, the solid volume fraction (0 % <  < 5 %, the Hartmann number (0 < Ha < 60 and the magnetic field angle (0 < ϕ < 90 on the flow field and temperature field and the heat transfer performance of the cavity. The obtained results indicate that the proposed method is a powerful approach to simulate the MHD natural convection of nanofluids in a square cavity. Also the numerical results show that for Ra = 105 and for the range of Hartmann number of this study, the heat transfer and fluid flow depend strongly upon the direction of magnetic field. Furthermore, the magnetic field influence on the effect of nanoparticles on the heat transfer enhancement is not significant.

  2. Proposed Cavity for Reduced Slip-Stacking Loss

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, J. [Indiana U.; Zwaska, R. [Fermilab

    2015-06-01

    This paper employs a novel dynamical mechanism to improve the performance of slip-stacking. Slip-stacking in an accumulation technique used at Fermilab since 2004 which nearly double the proton intensity. During slip-stacking, the Recycler or the Main Injector stores two particles beams that spatially overlap but have different momenta. The two particle beams are longitudinally focused by two 53 MHz 100 kV RF cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV RF cavity, with a frequency at the double the average of the upper and lower main RF frequencies. In simulation, we find the proposed RF cavity significantly enhances the stable bucket area and reduces slip-stacking losses under reasonable injection scenarios. We quantify and map the stability of the parameter space for any accelerator implementing slip-stacking with the addition of a harmonic RF cavity.

  3. Characteristic analysis of the optical delay in frequency response of resonant cavity enhanced (RCE) photodetectors

    Institute of Scientific and Technical Information of China (English)

    Guo Jian-Chuan; Zuo Yu-Hua; Zhang Yun; Ding Wu-Chang; Cheng Bu-Wen; Yu Jin-Zhong; Wang Qi-Ming

    2009-01-01

    With consideration of the modulation frequency of the input lightwave itself, we present a new model to calculate the quantum efficiency of RCE p-i-n photodetectors (PD) by superimposition of multiple reflected lightwaves. For the first time, the optical delay, another important factor limiting the electrical bandwidth of RCE p-i-n PD excluding the transit time of the carriers and RCd response of the photodetector, is analyzed and discussed in detail. The optical delay dominates the bandwidth of RCE p-i-n PD when its active layer is thinner than several 10 nm. These three limiting factors must be considered exactly for design of ultra-high-speed RCE p-i-n PD.

  4. Superconducting spoke cavities for high-velocity applications

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, Christopher S. [Old Dominion U.; Delayen, Jean R. [Old Dominion U., JLAB

    2013-10-01

    To date, superconducting spoke cavities have been designed, developed, and tested for particle velocities up to {beta}{sub 0}~0.6, but there is a growing interest in possible applications of multispoke cavities for high-velocity applications. We have explored the design parameter space for low-frequency, high-velocity, double-spoke superconducting cavities in order to determine how each design parameter affects the electromagnetic properties, in particular the surface electromagnetic fields and the shunt impedance. We present detailed design for cavities operating at 325 and 352 MHz and optimized for {beta}{sub 0}~=0.82 and 1.

  5. Human breath analysis via cavity-enhanced optical frequency comb spectroscopy

    CERN Document Server

    Thorpe, Michael J; Kirchner, Matthew S; Ye, Jun

    2007-01-01

    To date, researchers have identified over 1000 different compounds contained in human breath. These molecules have both endogenous and exogenous origins and provide information about physiological processes occurring in the body as well as environment-related ingestion or absorption of contaminants1,2. While the presence and concentration of many of these molecules are poorly understood, many 'biomarker' molecules have been correlated to specific diseases and metabolic processes. Such correlations can result in non-invasive methods of health screening for a wide variety of medical conditions. In this article we present human breath analysis using an optical-frequency-comb-based trace detection system with excellent performance in all criteria: detection sensitivity, ability to identify and distinguish a large number of biomarkers, and measurement time. We demonstrate a minimum detectable absorption of 8 x 10-10 cm-1, a spectral resolution of 800 MHz, and 200 nm of spectral coverage from 1.5 to 1.7 micron wher...

  6. Continuously tunable wavelength output from an Er-doped fiber femtosecond optical frequency comb with single-point frequency-doubling technique

    Science.gov (United States)

    Liu, H.; Cao, S. Y.; Meng, F.; Lin, B. K.; Fang, Z. J.

    2015-07-01

    Femtosecond optical frequency combs (FOFCs) with wavelengths covering the visible range have potential applications in the absolute frequency measurement of iodine-stabilized lasers and optical clock lasers. In this paper, an Er-FOFC with a tunable wavelength output from 689 to 813 nm based on the single-point frequency-doubling technique is demonstrated. Meanwhile, a beat frequency signal between the Er-FOFC and a tested laser at 729 nm with a signal-to-noise ratio of 30 dB at a resolution bandwidth of 100 kHz is obtained.

  7. Dye-laser-pumped Nd:GdCOB Self-frequency-doubling Laser

    Institute of Scientific and Technical Information of China (English)

    HOU Xueyuan; SUN Yuming; LI Yufei; ZHANG Shujun; CHENG Zhenxiang

    2000-01-01

    Nd:Ca4GDO(BO3)3, abbreviated as Nd:GdCOB, is a new multifunctional material for self-frequency-doubling green lasers. By using datachroom-5000 pulsed dye-laser as pumping source, we have achieved green laser output at 530.2 nm from a Nd:GdCOB crystal (7 mol-% Nd3+) uncoated HT film for 1.06 μm and 0.53 μm. The threshold energy is lower than 1.2 mJ. When the pumping energy is 17.5 mJ, the output energy of the green laser is 1.35 mJ and the corresponding conversion efficiency is 7.7%.

  8. Frequency-doubled diode laser for direct pumping of Ti:sapphire lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika;

    2012-01-01

    A single-pass frequency doubled high-power tapered diode laser emitting nearly 1.3 W of green light suitable for direct pumping of Ti:sapphire lasers generating ultrashort pulses is demonstrated. The pump efficiencies reached 75 % of the values achieved with a commercial solid-state pump laser....... However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20...... fs are measured. These results open the opportunity of establishing diode laser pumped Ti:sapphire lasers for e.g. biophotonic applications like retinal optical coherence tomography or pumping of photonic crystal fibers for CARS microscopy....

  9. Time-delay signatures in multi-transverse mode VCSELs subject to double-cavity polarization-rotated optical feedback

    Science.gov (United States)

    Lin, Hong; Khurram, Aliza; Hong, Yanhua

    2016-10-01

    Time delay (TD) signatures are studied experimentally in orthogonal polarizations and in individual transverse modes respectively in a VCSEL operating with three transverse modes. Different types of concealment of the TD signatures are observed when the polarization of feedback is rotated through large angles. Effects of feedback strength and external cavity length on the TD signatures are investigated. Weak feedback leads to better concealment of the TD signatures in the dominant polarization. When the round-trip time difference between the two external cavities is close to a half of the relaxation oscillation period, the TD signatures are minimized.

  10. Walk-off-induced modulation instability, temporal pattern formation, and frequency comb generation in cavity-enhanced second-harmonic generation

    CERN Document Server

    Leo, F; Ricciardi, I; De Rosa, M; Coen, S; Wabnitz, S; Erkintalo, M

    2016-01-01

    We derive a time-domain mean-field equation to model the full temporal and spectral dynamics of light in singly resonant cavity-enhanced second-harmonic generation systems. We show that the temporal walk-off between the fundamental and the second-harmonic fields plays a decisive role under realistic conditions, giving rise to rich, previously unidentified nonlinear behaviour. Through linear stability analysis and numerical simulations, we discover a new kind of quadratic modulation instability which leads to the formation of optical frequency combs and associated time-domain dissipative structures. Our numerical simulations show excellent agreement with recent experimental observations of frequency combs in quadratic nonlinear media [Phys. Rev. A 91, 063839 (2015)]. Thus, in addition to unveiling a new, experimentally accessible regime of nonlinear dynamics, our work enables predictive modeling of frequency comb generation in cavity-enhanced second-harmonic generation systems.

  11. Probe into Design of Novel Variable Cross-section Double Cavity Noise Absorption Structure%新型变截面双空腔吸声结构设计探讨

    Institute of Scientific and Technical Information of China (English)

    吕忠达; 陈涛; 邱贤锋

    2012-01-01

    In order to change current situations of serious pollution of traffic noise, this paper deigns a novel variable cross-section double cavity noise absorption structure, which is composed of five parts, i. e. metal acoustic panel, front variable cross-section cavity, middle absorption insulating layer, rear cavity and back sound insulating board. Based on measurement test for acoustic absorption factors in reverberation room, all acoustic absorption factors of this noise absorption structure at medium and low frequency range of 250 ~ 1 000 Hz are over 0. 65, and overall noise reduction coefficients are more than 0.60 with remarkable improvement in comparison with conventional noise absorption structure.%为改变高速公路交通噪声的严重污染现状,设计一种新型变截面双空腔吸声结构,其是由金属吸声板、前部变截面空腔、中间吸声隔层、后部空腔、背部隔声板5大部分构成.由混响室吸声系数的测定试验可知,该吸声结构在250~1 000 Hz中低频段的吸声系数均在0.65以上,总体降噪系数均大于0.60,较传统吸声结构,其吸声降噪效果有显著提升.

  12. Analysis on HEMP Effects of Double Metal Cavities with Penetrated Wire%双层金属腔体贯通导线HEMP耦合特性分析

    Institute of Scientific and Technical Information of China (English)

    柴焱杰; 赵煜; 许凯

    2014-01-01

    电磁脉冲( EMP )对电子设备构成严重威胁,研究电子设备HEMP效应是电磁兼容与电子设备安全领域的迫切需求。多层金属腔体是电子设备较为常见的一种结构形式,以一种带贯通导线的双层金属腔体为研究对象,基于时域有限差分方法( FDTD)建立计算模型,分析计算了贯通导线在高空核爆电磁脉冲( HEMP )入射波作用下对腔体内电路的耦合效应。仿真结果表明,贯通导线能将入射脉冲能量耦合进腔体内部,使内电路负载产生感应电流,当入射电场与贯通导线平面相互平行时影响较大,但相互垂直时仍会耦合一部分能量。所得结论可为多层腔体的电磁防护设计提供依据。%Electromagnetic pulses ( EMP ) have a serious threat on electronic equipment, so the study of HEMP effects is an urgent task in the fields of electromagnetic compatibility and electronic equipment safety. Multi⁃layer metal cavities are common struc⁃tures of electronic equipment, so the paper focuses on a kind of double wall cavities with penetrated wire. Based on the finite difference time domain method ( FDTD) , it analyses and calculates the internal circuit coupling effects of the penetrated wire in a structure of double wall cavities under the high-altitude electromagnetic pulse ( HEMP ) plane wave. The results show that the penetrated wires couple the incident pulse energy into the internal cavity, so load current is induced in the internal circuit; there is a greater impact when the incident electric field is parallel to the plane of the penetrated wires, but when they are perpendicular to each other, part of the energy is still coupled. The conclusions provide a reference for the electromagnetic protective design of multi-layer cavities.

  13. Influence of aspheric intraocular lens on frequency doubling technology and contrast sensitivity: a fellow eye study

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2014-12-01

    Full Text Available Purpose: To evaluate whether implantation of an aspheric intraocular lens (IOL results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery and, therefore, changes on frequency-doubling technology (FDT testing. Methods: The present prospective clinical study enrolled 25 patients with bilateral cataract (50 eyes, who randomly received either an aspheric (Akreos AO or a spherical (Akreos Fit IOL in one eye and the other IOL in the second eye. Assessment 12 months postoperatively included photopic and mesopic contrast sensitivity testing. Higher-order aberrations (HOAs were computed. FDT testing was divided into four areas to evaluate the variation of the values at different points. The median values of the local pattern thresholds (median area contrast sensitivity [MACS] obtained with that division were calculated. Results: The Akreos AO group obtained statistically significantly lower values of HOAs and spherical aberration compared with the Akreos Fit group. There was a statistically significant between-group difference in contrast sensitivity under mesopic conditions at all spatial frequencies. No statistically significant differences were observed in mean deviation and pattern standard deviation. The aspheric IOL exhibited higher MACS in all areas, although a statistically significant difference was reached only in the 20-degree field area (P=0.043. Conclusion: Aspheric IOLs significantly reduced spherical aberration and HOAs, improving mesopic contrast sensitivity. Although there was a trend toward slightly improved FDT in the aspheric IOL group, it was not statistically significant.

  14. Double-grid finite-difference frequency-domain (DG-FDFD) method for scattering from chiral objects

    CERN Document Server

    Alkan, Erdogan; Elsherbeni, Atef

    2013-01-01

    This book presents the application of the overlapping grids approach to solve chiral material problems using the FDFD method. Due to the two grids being used in the technique, we will name this method as Double-Grid Finite Difference Frequency-Domain (DG-FDFD) method. As a result of this new approach the electric and magnetic field components are defined at every node in the computation space. Thus, there is no need to perform averaging during the calculations as in the aforementioned FDFD technique [16]. We formulate general 3D frequency-domain numerical methods based on double-grid

  15. Efficient intracavity frequency doubling of a high-repetition-rate diode-pumped Nd:YAG laser.

    Science.gov (United States)

    Hanson, F; Poirier, P

    1994-10-01

    Efficient operation of a pulsed, high-repetition-rate diode-pumped and intracavity frequency-doubled Nd:YAG laser is reported. A 3-mm-diameter laser rod was side-pumped with a 5-bar stack of high-duty-cycle 1-cm diodearrays. The average Q-switched power at 1.06microum was 3.8 W at 1.33 kH(z), and more than 4 W at 0.532 ,microm wasobtained through intracavity frequency doubling with LiB(3)O(5).

  16. Quartz optical filter for wavelength selection of frequency-doubled laser based on optical rotatory dispersion effect

    Institute of Scientific and Technical Information of China (English)

    Shan Zhang; Fuquan Wu; Wendi Wu; Haifeng Wang

    2007-01-01

    Based on the optical rotatory dispersion effect, an optical filter for selecting the second harmonic of a frequency-doubled laser is constructed from quartz in combination with polarizers. The operating principle is analyzed by matrix formulation, and the result indicates that the second harmonic of a frequency-doubled laser will be obtained when the rotation angle has a difference of (2n + 1)π/2 (n = 0, 1, 2, 3,… ) between the two polarizations of the second-harmonic laser and the fundamental laser. The spectrum of the output laser is taken by the AQ-6315A spectrometer, and the experimental results are in good agreement with the theoretical results.

  17. Fast Computation of Frequency Response of Cavity-Backed Apertures Using MBPE in Conjunction with Hybrid FEM/MoM Technique

    Science.gov (United States)

    Reddy, C. J.; Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.

    2004-01-01

    The hybrid Finite Element Method(FEM)/Method of Moments(MoM) technique has become popular over the last few years due to its flexibility to handle arbitrarily shaped objects with complex materials. One of the disadvantages of this technique, however, is the computational cost involved in obtaining solutions over a frequency range as computations are repeated for each frequency. In this paper, the application of Model Based Parameter Estimation (MBPE) method[1] with the hybrid FEM/MoM technique is presented for fast computation of frequency response of cavity-backed apertures[2,3]. In MBPE, the electric field is expanded in a rational function of two polynomials. The coefficients of the rational function are obtained using the frequency-derivatives of the integro-differential equation formed by the hybrid FEM/MoM technique. Using the rational function approximation, the electric field is calculated at different frequencies from which the frequency response is obtained.

  18. 10.2-W Q-switched intracavity frequency-doubled Nd:YVO(4)/LBO red laser double-end-pumped by laser-diode-arrays.

    Science.gov (United States)

    Qin, Wan; Du, Chenlin; Ruan, Shuangchen; Wang, Yuncai

    2007-02-19

    We report a high-power diode-double-end-pumped Q-switched Nd:YVO4 red laser through intracavity frequency-doubling with a type-I critical phase-matched LBO crystal. At a repetition frequency of 21.72 kHz, a maximum average output power of 10.2 W at 671 nm was measured to while the incident pump power was 78.4 W, the corresponding optical conversion efficiency was 13.0%, with a pulse width of about 94 ns and a pulse energy of 469.6 muJ, the peak power was 5.0 kW. At an average output power around 9.6 W a power stability better than 2.3% was maintained for half an hour. PMID:19532392

  19. LDPC based time-frequency double differential space-time coding for multi-antenna OFDM systems

    Institute of Scientific and Technical Information of China (English)

    TIAN Ji-feng; JIANG Hai-ning; SONG Wen-tao; LUO Han-wen

    2006-01-01

    Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differential space-time (DDST) coding is of special interest because it is applicable to continuous fast time-varying channels. However, it is less effective in frequency-selective fading channels. This paper's authors derived a novel time-frequency double differential space-time (TF-DDST)coding scheme for multi-antenna orthogonal frequency division multiplexing (OFDM) systems ina time-varying frequency-selective fading environment, where double differential space-time coding is introduced into both time domain and frequency domain. Our proposed TF-DDST-OFDM system has a low-complexity non-coherent decoding scheme and is robust for time- and frequency-selective Rayleigh fading. In this paper, we also propose the use of state-of-the-art low-density parity-check (LDPC) code in serial concatenation with our TF-DDST scheme as a channel code. Simulations revealed that the LDPC based TF-DDST OFDM system has low decoding complexity and relatively better performance.

  20. Production of a coherent pair of light beams with a microwave frequency difference from a single extended-cavity diode laser.

    Science.gov (United States)

    Yim, Sin Hyuk; Cho, D

    2010-02-01

    We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.

  1. Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser.

    Science.gov (United States)

    Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J; Tang, Shuo

    2016-05-01

    We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications. PMID:27231633

  2. Use of spin labels to study membrane proteins by high-frequency electron nuclear double resonance spectroscopy

    NARCIS (Netherlands)

    Orlinkskii, S.B.; Borovykh, I.V.; Zielke, V.; Steinhoff, H.J.

    2007-01-01

    The applicability of spin labels to study membrane proteins by high-frequency electron nuclear double resonance spectroscopy is demonstrated. With the use of bacteriorhodopsin embedded in a lipid membrane as an example, the spectra of protons of neighboring amino acids are recorded, electric field g

  3. Second-order fractional Talbot effect induced frequency-doubling optical pulse injection for 40 GHz rational-harmonic mode-locking of an SOA fiber laser

    International Nuclear Information System (INIS)

    A second-order fractional Talbot effect induced frequency-doubling of a 10 GHz optical pulse-train is demonstrated to backward injection mode-lock a semiconductor optical amplifier fiber laser (SOAFL) for 40 GHz rational-harmonic mode-locking (RHML). That is, a real all-optical gain-modulation of the SOAFL can be created by injecting such a time-multiplexed but pseudo-frequency-doubled pulse-train into the cavity. The time-multiplexing pulse-train can thus be transformed into a frequency-multiplied pulse-train via cross-gain modulation (XGM). The optical pulse-train at 10 GHz is generated by nonlinearly driving an electro-absorption modulator (EAM), which experiences the second-order fractional Talbot effect after propagating through a 4 km long dispersion compensation fiber (DCF). The DCF not only plays the role of frequency-doubler but also compensates the frequency chirp of the 10 GHz optical pulse-train. The pulsewidth broadening from 22 to 60 ps for initiating the time-domain Talbot effect is simulated by the nonlinear Schrödinger equation. With careful detuning of the RF modulation power of the EAM at 5 dBm, the generated 20 GHz optical pulse-train exhibits a positive frequency chirp with minimum peak-to-peak value of 2 GHz, and the peak-amplitude fluctuation between adjacent pulses is below 1.4%. In comparison with the SOAFL pulse-train repeated at 40 GHz generated by the fourth-order purely RHML process, the optimized second-order fractional Talbot effect in combination with the second-order RHML mechanism significantly enhances the modulation-depth of RHML, thus improving the on/off extinction ratio of the 40 GHz SOAFL pulse-train from 1.8 to 5.6 dB. Such a new scheme also provides a more stable 40 GHz RHML pulse-train from the SOAFL with its timing jitter reducing from 0.51 to 0.23 ps. (paper)

  4. The importance of oral hygiene on children of Romany ethnic group with the focus on preventive measures resulting in the reduction of oral cavity diseases frequency.

    OpenAIRE

    Hanusová, Markéta

    2015-01-01

    The main objective of this diploma thesis is to describe an awareness and level of oral hygiene of children of Romany ethnic group and subsequently optimize the care of oral cavity leading to the reduction in frequency of hanging apparatus illnesses. The other target of this thesis is a preparation of educational program that would motivate children to correct and regular dental hygiene. The thesis deals with history and characteristic of Romany ethnic group, issues of Romany children and low...

  5. Frequency Modulated Integrated Cavity Output Spectroscopy: A General Technique for Trace Gas and Isotope Measurements with Unprecedented Sensitivity Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new technique is proposed for improved trace gas detection and measurement that combines the high absorption depths afforded by mid-infrared Integrated Cavity...

  6. Power-scalable internal frequency doubling scheme for continuous-wave fiber lasers

    OpenAIRE

    Cieslak, Rafal; Clarkson, W.Andrew

    2011-01-01

    We describe a simple power-scalable concept for efficient second harmonic generation in a cladding-pumped continuous-wave fiber laser. Our approach makes use of an internal resonant enhancement cavity to increase the intracavity power and second harmonic conversion efficiency without the need for active cavity length control and stabilization. This technique has been applied to a cladding-pumped Yb-doped fiber laser yielding 15 W of linearly-polarized continuous-wave green output (at 540 nm) ...

  7. Simultaneous and continuous multiple wavelength absorption spectroscopy on nanoliter volumes based on frequency-division multiplexing fiber-loop cavity ring-down spectroscopy.

    Science.gov (United States)

    Waechter, Helen; Munzke, Dorit; Jang, Angela; Loock, Hans-Peter

    2011-04-01

    We demonstrate a method for measuring optical loss simultaneously at multiple wavelengths with cavity ring-down spectroscopy (CRD). Phase-shift CRD spectroscopy is used to obtain the absorption of a sample from the phase lag of intensity modulated light that is entering and exiting an optical cavity. We performed dual-wavelength detection by using two different laser light sources and frequency-division multiplexing. Each wavelength is modulated at a separate frequency, and a broadband detector records the total signal. This signal is then demodulated by lock-in amplifiers at the corresponding two frequencies allowing us to obtain the phase-shift and therefore the optical loss at several wavelengths simultaneously without the use of a dispersive element. In applying this method to fiber-loop cavity ring-down spectroscopy, we achieve detection at low micromolar concentrations in a 100 nL liquid volume. Measurements at two wavelengths (405 and 810 nm) were performed simultaneously on two dyes each absorbing at mainly one of the wavelengths. The respective concentrations could be quantified independently in pure samples as well as in mixtures. No crosstalk between the two channels was observed, and a minimal detectable absorbance of 0.02 cm(-1) was achieved at 405 nm. PMID:21355542

  8. Evaluation of GdCOB:Nd 3+ for self-frequency doubling in the optimum phase matching direction

    Science.gov (United States)

    Brenier, A.; Majchrowski, A.; Michalski, E.; Łukasiewicz, T.

    2003-03-01

    We have exhibited the spectroscopic properties of GdCOB:Nd 3+ in the optimum phase matching direction for frequency doubling, i.e., θ=66.3° and φ=134.4°, in the two n + and n - directions of polarization. This direction is suitable for self-frequency doubling of the 1060 nm laser emission in type I configuration. The laser emission cross-section is found reasonably high: 6×10 -20 cm2. The effective nonlinear optical coefficient for SHG at 1088 nm was found 1.89 times the NGAB one, i.e., about 2.6 pm/V. From a direct comparison of self-frequency doubling under the same experimental conditions, we have demonstrated that GdCOB:Nd allowed to reach 78% of the efficiency of a NGAB sample. This is quite a good result, keeping in mind that NGAB seems to be the most efficient self-doubling crystal at the present time.

  9. A Novel Boost Converter with Double Frequency%一种新型双频Boost变换器

    Institute of Scientific and Technical Information of China (English)

    李向丽; 漆汉宏; 魏艳君; 高云云

    2011-01-01

    A novel topolopy of Boost converter with double frequency is proposed. The current flowing of the converter in the high frequency unit is diverted by the low frequency one compared with the traditional high frequency Boost converter. The converter can improve the dynamic response with high efficiency, which is suitable for high power applications.The working principle of double frequency Boost converter is analyzed and the state equation of four swicth state is established.The results proves that the steady and dynamic performance of double frequency Boost converter are same as the high frequency Boost converter, but the efficiecy of it is improved obviously.The experimental results and simulation results verify the correctness of theoretical analysis.%提出一种新型双频Boost变换器拓扑结构.与传统Boost变换器相比.该变换器通过叠加低频Boost单元对高频Boost单元进行分流,在改善动态特性的同时提高效率,适用于大中功率场合.对双频Boost变换器的工作原理进行了分析,建立了4种开关状态的状态方程.结果表明双频Boost变换器的稳态及动态性能与单个高频Boost变换器基本相同,但效率却明显提高,仿真和实验结果验证了理论分析的正确性.

  10. Design of Superconducting Spoke Cavities for High-velocity Applications

    International Nuclear Information System (INIS)

    Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β0 ∼ 0.15 to β0 ∼ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β0 = 0.82 and β0 = 1. Accelerating cavities intended to accelerate light particles or high-energy heavy particles above β0 = 0.6 to β0 = 0.8 have typically been of the elliptical type. Single and multiple-gap spoke cavities offer several advantages over their elliptical counterparts. Since the diameter of the cavity is on the order of λ/2, the frequency is half that of an elliptical cavity for the same transverse dimension. The lower frequency allows for 4 K operation as well as a higher voltage gain over a wider range of velocities. We report here on the design of double-spoke 352 MHz cavities of β0 = 0.82 and 1.

  11. Possible influence of surface oxides on the optical response of high-purity niobium material used in the fabrication of superconducting radio frequency cavity

    Science.gov (United States)

    Singh, Nageshwar; Deo, M. N.; Roy, S. B.

    2016-09-01

    We have investigated the possible influence of surface oxides on the optical properties of a high-purity niobium (Nb) material for fabrication of superconducting radio frequency (SCRF) cavities. Various peaks in the infrared region were identified using Fourier transform infrared and Raman spectroscopy. Optical response functions such as complex refractive index, dielectric and conductivity of niobium were compared with the existing results on oxides free Nb and Cu. It was observed that the presence of a mixture of niobium-oxides, and probably near other surface impurities, appreciably influence the conducting properties of the material causing deviation from the typical metallic characteristics. In this way, the key result of this work is the observation, identification of vibrational modes of some of surface complexes and study of its influences on the optical responses of materials. This method of spectroscopic investigation will help in understanding the origin of degradation of performance of SCRF cavities.

  12. High power red laser at 671nm by intracavity frequency doubling of a Nd:YVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Yao Ai-Yun; Hou Wei; Li Hui-Qing; Bi Yong; Li Rui-Ning; Geng Ai-Cong; Kong Yu-Peng; Cui Da-Fu; Xu Zu-Yan

    2005-01-01

    This paper reports a high-power quasi-continuous wave (quasi-CW) source of red laser at 671nm obtained by intracavity frequency doubling of a double-end-pumped 1342nm Nd:YVO4 laser, based on the nonlinear crystal LiB3O5 (LBO)The average output power of 2.9W at 671nm was obtained at the incident pump power of 19.5W. The overall optical to optical efficiency is 14.9%. We have analyzed the influence of the optimal pump size, the optimal focal position and the reduction of the thermal effect on high output. The combination of double-end-pumping and the quasi-CW performance greatly reduces the thermal effect.

  13. Measures of maximum magnetic field in 3 GHz radio frequency superconducting cavities; Mesures du gradient accelerateur maximum dans des cavites supraconductrices en regime impulsionnel a 3 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Catherine [Paris-11 Univ., 91 Orsay (France)

    2000-01-19

    Theoretical models have shown that the maximum magnetic field in radio frequency superconducting cavities is the superheating field H{sub sh}. For niobium, H{sub sh} is 25 - 30% higher than the thermodynamical H{sub c} field: H{sub sh} within (240 - 274) mT. However, the maximum magnetic field observed so far is in the range H{sub c,max} = 152 mT for the best 1.3 GHz Nb cavities. This field is lower than the critical field H{sub c1} above which the superconductor breaks up into divided normal and superconducting zones (H{sub c1}{<=}H{sub c}). Thermal instabilities are responsible for this low value. In order to reach H{sub sh} before thermal breakdown, high power short pulses are used. The cavity needs then to be strongly over-coupled. The dedicated test bed has been built from the collaboration between Istituto Nazionale di Fisica Nucleare (INFN) - Sezione di Genoa, and the Service d'Etudes et Realisation d'Accelerateurs (SERA) of Laboratoire de l'Accelerateur Lineaire (LAL). The maximum magnetic field, H{sub rf,max}, measurements on INFN cavities give lower results than the theoretical speculations and are in agreement with previous results. The superheating magnetic fields is linked to the magnetic penetration depth. This superconducting characteristic length can be used to determine the quality of niobium through the ratio between the resistivity measured at 300 K and 4.2 K in the normal conducting state (RRR). Results have been compared to previous ones and agree pretty well. They show that the RRR measured on cavities is superficial and lower than the RRR measured on samples which concerns the volume. (author)

  14. Squeezing based on nondegenerate frequency doubling internal to a realistic laser

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Tidemand-Lichtenberg, Peter; Buchhave, Preben

    2004-01-01

    We investigate theoretically the quantum fluctuations of the fundamental field in the output of a nondegenerate second-harmonic generation process occurring inside a laser cavity. Due to the nondegenerate character of the nonlinear medium, a field orthogonal to the laser field is for some operating...

  15. High-performance at low cost: the challenge manufacturing frequency doubled green semiconductor lasers for mass markets

    Science.gov (United States)

    Hoefer, T.; Schmitt, M.; Schwarz, T.; Kuehnelt, M.; Schulz, R.; Pietzonka, I.; Lindberg, H.; Lauer, C.; Lutgen, S.; Steegmueller, U.; Strauss, U.

    2010-02-01

    Laser projection arising as a new application in the consumer market has been the driving force for OSRAM Opto Semiconductors to develop a frequency doubled semiconductor laser and the production technology necessary to make the complexity of an advanced laser system affordable. Optically pumped frequency doubled semiconductor lasers provide an ideal platform to serve the laser projection application. Based on this scalable technology, we developed a 50 mW green laser comprising all the properties that can be expected from a high performance laser: Excellent beam quality and low noise, high speed modulation, good efficiency and long life time. More than that, the package is very compact (green laser, and will also present results from reliability testing and production monitoring.

  16. Angular Multiplexing Storage in Azo-polymer Liquid Crystal Films Using Shearing Interferometer of Double-frequency Grating

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jiangying; MING Hai; WANG Pei; WU Yunxia; XIE Jianping; ZHANG Qijin; LIU Jian

    2002-01-01

    In this paper, the shearing interferometer of a double-frequency grating (DFG) and a small compact Nd∶YVO4 double frequency laser at 532 nm are used to study the multiple storage in azo-polymer liquid crystal (PLC) films. In a principle experiment, the angle-encoded multiple gratings are recorded and the experimental results give triplex gratings at the same region in azo-PLC films, the angle between two adjacent grating vectors being 45°. Compared to the two-beam interferometer and four-wave mixing method, this method has simple configuration, high fringe contrast and quake-proof. A compatible angular multiplexing storage system in azo-PLC films is proposed.

  17. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm

    Science.gov (United States)

    Saarinen, Esa J.; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G.

    2016-03-01

    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  18. Role of the protein cavity in phytochrome chromoprotein assembly and double-bond isomerization: a comparison with model compounds.

    Science.gov (United States)

    Rohmer, Thierry; Lang, Christina; Gärtner, Wolfgang; Hughes, Jon; Matysik, Jörg

    2010-01-01

    Difference patterns of (13)C NMR chemicals shifts for the protonation of a free model compound in organic solution, as reported in the literature (M. Stanek, K. Grubmayr [1998] Chem. Eur. J.4, 1653-1659), were compared with changes in the protonation state occurring during holophytochrome assembly from phycocyanobilin (PCB) and the apoprotein. Both processes induce identical changes in the NMR signals, indicating that the assembly process is linked to protonation of the chromophore, yielding a cationic cofactor in a heterogeneous, quasi-liquid protein environment. The identity of both difference patterns implies that the protonation of a model compound in solution causes a partial stretching of the geometry of the macrocycle as found in the protein. In fact, the similarity of the difference pattern within the bilin family for identical chemical transformations represents a basis for future theoretical analysis. On the other hand, the change of the (13)C NMR chemical shift pattern upon the Pr --> Pfr photoisomerization is very different to that of the free model compound upon ZZZ --> ZZE photoisomerization. Hence, the character of the double-bond isomerization in phytochrome is essentially different from that of a classical photoinduced double-bond isomerization, emphasizing the role of the protein environment in the modulation of this light-induced process. PMID:20492561

  19. Using a double-frequency RF system to facilitate on-axis beam accumulation in a storage ring

    CERN Document Server

    Jiang, B C; Tian, S Q; Zhang, M Z; Zhang, Q L

    2016-01-01

    An on-axis injection scheme using a double-frequency RF system in a storage ring with small dynamic aperture is proposed. By altering RF voltages, empty RF buckets can be created which will be used for on-axis injection. After bunches are injected, a reverse RF voltage altering process is performed and the injected bunches can be longitudinally dumped to the main RF buckets. The scheme allows reaping the advantages of the on-axis injection while still performing accumulation.

  20. Self-frequency-doubled vibronic yellow Yb:YCOB laser at the wavelength of 570  nm.

    Science.gov (United States)

    Fang, Qiannan; Lu, Dazhi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-03-01

    A watt-level self-frequency-doubled yellow laser at the 570 nm wavelength was realized by taking advantage of the vibronic emission of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of the principal planes with the maximum effective nonlinear coefficient. Fluorescence spectroscopic properties of Yb:YCOB were studied, which showed that it had broad and anisotropic vibronic emission with a small peak at ∼1130  nm. By suppressing the electronic emission, the polarized vibronic Yb:YCOB radiation was realized with the fundamental wavelength shifting from 1130 nm to 1140 nm. By employing the self-frequency-doubling behavior of Yb:YCOB, the self-frequency-doubled yellow laser was achieved with a maximum output power of 1.08 W at 570 nm. This work provides an unprecedented and efficient way to generate yellow lasers with a compact microchip structure that may have promising applications in some regimes including medicine, entertainment, and scientific research. PMID:26974101

  1. A high-power high-stability Q-switched green laser with intracavity frequency doubling using a diode-pumped composite ceramic Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Wang Yu-Ye; Xu De-Gang; Liu Chang-Ming; Wang Wei-Peng; Yao Jian-Quan

    2012-01-01

    We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd:YAG in a straight plano-concave cavity. The temperature distribution in composite ceramic Nd:YAG crystal is numerically analyzed and compared with that of conventional Nd:YAG crystal.By using a composite ceramic Nd:YAG rod and a type-Ⅱ high gray track resistance KTP (HGTR-KTP) crystal,a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz,with a diode-to-green optical conversion of 14.68%,and a pulse width of 162 ns.To the best of our knowledge,both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd:YAG laser to date.The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.

  2. Meta-analysis of the diagnostic efficiency of frequency-doubling technology for primary glaucoma

    Institute of Scientific and Technical Information of China (English)

    LIU Ting; HE Xiangge

    2007-01-01

    The overall diagnostic capabilities and utility of frequency-doubling technology (FDT) in patients with primary glaucoma,which was diagnosed by standard automated perimetry (SAP) and/or optic disc appearance as the gold standard,were assessed.A comprehensive electric retrieval in MEDLINE,EMBASE,Cochrane Library,BIOSIS,Previews,HMIC,IPA,OVID,CNKI,CBMdisc,VIP information,CMCC,CCPD,SSreader,21dmedia and manual retrieval in related textbooks,journals,congress articles and their references at home and abroad were performed to identify relevant articles in English or Chinese.The corresponding references were retrieved by means of electric retrieval and manual retrieval from different databases or materials.Criteria for inclusion or exclusion were established according to validity criteria for diagnostic studies published by the Cochrane Methods Group on Screening and Diagnostic Tests.The quality of the included articles was then assessed and characteristics were extracted.Statistical analysis was performed with Meta Test version 0.6 software to test the heterogeneity of the included articles.The appropriate effects model was selected to calculate pooled weighted sensitivity and specificity.Summary receiver operating characteristic (SROC)curve was drawn and the area under the curve (AUC)was calculated.Finally,sensitivity analysis was performed.Twenty-one studies out of 206 retrieved articles were included,with a total of 3172 patients.The reported sensitivity of FDT ranged from 0.51 to 1.00,and specificity from 0.58 to 1.00.The pooled weighted sensitivity and specificity of FDT with 95% confidence intervals (95% CI) after correction for standard error were 0.86 (0.80-0.90) and 0.87 (0.81-0.91),respectively.The AUC of SROC was 93.01%.Sensitivity analysis demonstrated no disproportionate influences of individual studies.The included articles are of good quality and FDT can be a highly efficient diagnostic test for primary glaucoma based on Meta-analysis.

  3. Double-wavelet approach to study frequency and amplitude modulation in renal autoregulation

    DEFF Research Database (Denmark)

    Sosnovtseva, Olga; Pavlov, A N; Mosekilde, E;

    2004-01-01

    Biological time series often display complex oscillations with several interacting rhythmic components. Renal autoregulation, for instance, involves at least two separate mechanisms both of which can produce oscillatory variations in the pressures and flows of the individual nephrons. Using double...

  4. Double-wavelet approach to study frequency and amplitude modulation in renal autoregulation

    DEFF Research Database (Denmark)

    Sosnovtseva, Olga; Pavlov, A.N.; Mosekilde, Erik;

    2004-01-01

    Biological time series often display complex oscillations with several interacting rhythmic components. Renal autoregulation, for instance, involves at least two separate mechanisms both of which can produce oscillatory variations in the pressures and flows of the individual nephrons. Using doubl...

  5. MOSFET technologies for double-pole four-throw radio-frequency switch

    CERN Document Server

    Srivastava, Viranjay M

    2014-01-01

    This book provides analysis and discusses the design of various MOSFET technologies which are used for the design of Double-Pole Four-Throw (DP4T) RF switches for next generation communication systems. The authors discuss the design of the (DP4T) RF switch by using the Double-Gate (DG) MOSFET, as well as the Cylindrical Surrounding double-gate (CSDG) MOSFET.  The effect of HFO2 (high dielectric material) in the design of DG MOSFET and CSDG MOSFET  is also explored. Coverage includes comparison of Single-gate MOSFET and Double-gate MOSFET switching parameters, as well as testing of MOSFETs parameters using image acquisition.  ·         Provides a single-source reference to the latest technologies for the design of Double-gate MOSFET, Cylindrical Surrounding double-gate MOSFET and HFO2 based MOSFET; ·         Explains the design of RF switches using the technologies presented and simulates switches; ·         Verifies parameters and discusses feasibility of devices and switches.

  6. Research on 561 nm Frequency-Double All-Solid-State Laser%全固态561 nm倍频激光器研究

    Institute of Scientific and Technical Information of China (English)

    邵志强; 高兰兰; 张辰

    2013-01-01

    561 nm laser output is achieved from LBO intra-cavity frequency doubling of a laser in which Nd:YAG is end-pumped by LD. Using the 2 mm×2 mm×10 mm LBO crystal with type-1 phase matching cutting, the 561 nm laser output power is 123 mW when the pump power is 5 W. The conversion efficiency of 2. 46% is obtained. The frequency-doubled light waves of 556 nm and 558 nm easily appear in experiment. From the influence of nonlinear conversion efficiency on fundamental-frequency light oscillation, the reason of 1112 nm and 1116 nm line oscillation is analyzed. As a contrast, we carry out the same experiment using a 2 mm×2 mm×8 mm KTP crystal with type-II phase matching cutting. Results show that the laser is easy to realized 561 nm single spectral-line laser. The experimental results and theoretical analysis are consistent with each other.%报道了利用激光二极管端面抽运Nd:YAG晶体,通过LBO非线性晶体腔内倍频实现的561 nm激光输出.LBO晶体尺寸为2 mm×2 mm×10 mm,采用I类相位匹配切割.抽运功率为5W时,561 am的最大输出功率为123 mW,此时的光-光转换效率为2.46%.实验中发现激光器很容易同时出现556 nm及558 nm倍频光.从非线性转换效率对基频光振荡的影响角度出发,分析了1112 nm与1116 nm谱线起振的原因.作为对比,利用允许角范围小的KTP作为倍频晶体进行了同样的实验,KTP晶体的尺寸为2 mm×2 mm×8 mm,采用Ⅱ类相位匹配切割.实验结果显示,在KTP晶体倍频情况下,激光器很容易实现561 nm单谱线激光输出.实验结果与理论分析相一致.

  7. Finite element analysis and frequency shift studies for the bridge coupler of the coupled cavity linear accelerator of the spallation neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z. (Zukun)

    2001-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron scattering research facility. The linear accelerator (linac) is the principal accelerating structure and divided into a room-temperature linac and a superconducting linac. The normal conducting linac system that consists of a Drift Tube Linac (DTL) and a Coupled Cavity Linac (CCL) is to be built by Los Alamos National Laboratory. The CCL structure is 55.36-meters long. It accelerates H- beam from 86.8 Mev to 185.6 Mev at operating frequency of 805 MHz. This side coupled cavity structure has 8 cells per segment, 12 segments and 11 bridge couplers per module, and 4 modules total. A 5-MW klystron powers each module. The number 3 and number 9 bridge coupler of each module are connected to the 5-MW RF power supply. The bridge coupler with length of 2.5 {beta}{gamma} is a three-cell structure and located between the segments and allows power flow through the module. The center cell of each bridge coupler is excited during normal operation. To obtain a uniform electromagnetic filed and meet the resonant frequency shift, the RF induced heat must be removed. Thus, the thermal deformation and frequency shift studies are performed via numerical simulations in order to have an appropriate cooling design and predict the frequency shift under operation. The center cell of the bridge coupler also contains a large 4-inch slug tuner and a tuning post that used to provide bulk frequency adjustment and field intensity adjustment, so that produce the proper total field distribution in the module assembly.

  8. Natural Frequency Analysis of Two Nonlinear Panels Coupled with a Cavity Using the Approximate Elliptic Integral Solution and the Method of Harmonic Residual Minimization

    Directory of Open Access Journals (Sweden)

    Y. Y. Lee

    2015-01-01

    Full Text Available The nonlinear structural acoustic problem considered in this study is the nonlinear natural frequency analysis of flexible double panels using the elliptic integral solution method. There are very limited studies for this nonlinear structural-acoustic problem, although many nonlinear plate or linear double panel problems have been tackled and solved. A multistructural/acoustic modal formulation is derived from two coupled partial differential equations which represent the large amplitude structural vibrations of the flexible panels and acoustic pressure induced within the air gap. One is the von Karman’s plate equation and the other is the homogeneous wave equation. The results obtained from the proposed method approach are verified with those from a numerical method. The effects of vibration amplitude, gap width, aspect ratio, the numbers of acoustic modes and harmonic terms, and so forth on the resonant frequencies of the in-phase and out of phase modes are examined.

  9. Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rufai, O. R. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Bharuthram, R. [Office of the Deputy Vice Chancellor (Academic), University of the Western Cape, Bellville (South Africa); Singh, S. V. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India); School of Chemistry and Physics, University of Kwa-Zulu Natal, Durban (South Africa); Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India)

    2012-12-15

    Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to be 49 mV/m which is in agreement of the Viking observations in this region.

  10. A generalization of the double-corner-frequency source spectral model and its use in the SCEC BBP validation exercise

    Science.gov (United States)

    Boore, David M.; Di Alessandro, Carola; Abrahamson, Norman A.

    2014-01-01

    The stochastic method of simulating ground motions requires the specification of the shape and scaling with magnitude of the source spectrum. The spectral models commonly used are either single-corner-frequency or double-corner-frequency models, but the latter have no flexibility to vary the high-frequency spectral levels for a specified seismic moment. Two generalized double-corner-frequency ω2 source spectral models are introduced, one in which two spectra are multiplied together, and another where they are added. Both models have a low-frequency dependence controlled by the seismic moment, and a high-frequency spectral level controlled by the seismic moment and a stress parameter. A wide range of spectral shapes can be obtained from these generalized spectral models, which makes them suitable for inversions of data to obtain spectral models that can be used in ground-motion simulations in situations where adequate data are not available for purely empirical determinations of ground motions, as in stable continental regions. As an example of the use of the generalized source spectral models, data from up to 40 stations from seven events, plus response spectra at two distances and two magnitudes from recent ground-motion prediction equations, were inverted to obtain the parameters controlling the spectral shapes, as well as a finite-fault factor that is used in point-source, stochastic-method simulations of ground motion. The fits to the data are comparable to or even better than those from finite-fault simulations, even for sites close to large earthquakes.

  11. Broadband frequency conversion

    OpenAIRE

    Sanders, Nicolai Højer; Jensen, Ole Bjarlin; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2012-01-01

    We demonstrate a method for frequency conversion of broadly tunable or broad bandwidth light in a static, passive setup. Using simple optical components like lenses, mirrors and gratings and a BiBO crystal as the nonlinear material, we are able to frequency double a single-frequency, tunable, external cavity diode laser in the 1020-1090 nm range into the 510-545 nm range with almost equal efficiency for all wavelengths. Phase matching is obtained as follows; a diffraction grating is used to d...

  12. Odd-paired controls frequency doubling in Drosophila segmentation by altering the pair-rule gene regulatory network

    Science.gov (United States)

    Clark, Erik; Akam, Michael

    2016-01-01

    The Drosophila embryo transiently exhibits a double-segment periodicity, defined by the expression of seven 'pair-rule' genes, each in a pattern of seven stripes. At gastrulation, interactions between the pair-rule genes lead to frequency doubling and the patterning of 14 parasegment boundaries. In contrast to earlier stages of Drosophila anteroposterior patterning, this transition is not well understood. By carefully analysing the spatiotemporal dynamics of pair-rule gene expression, we demonstrate that frequency-doubling is precipitated by multiple coordinated changes to the network of regulatory interactions between the pair-rule genes. We identify the broadly expressed but temporally patterned transcription factor, Odd-paired (Opa/Zic), as the cause of these changes, and show that the patterning of the even-numbered parasegment boundaries relies on Opa-dependent regulatory interactions. Our findings indicate that the pair-rule gene regulatory network has a temporally modulated topology, permitting the pair-rule genes to play stage-specific patterning roles. DOI: http://dx.doi.org/10.7554/eLife.18215.001 PMID:27525481

  13. Sub-MHz accuracy measurement of the S(2) 2-0 transition frequency of D2 by Comb-Assisted Cavity Ring Down spectroscopy

    Science.gov (United States)

    Mondelain, D.; Kassi, S.; Sala, T.; Romanini, D.; Gatti, D.; Campargue, A.

    2016-08-01

    The line position of the very weak S(2) transition of deuterium in the 2-0 band has been measured with a Comb-Assisted Cavity Ring Down spectrometer. The high sensitivity spectra were recorded at 5 and 10 mbar with a Noise Equivalent Absorption, αmin, of 8 × 10-11 cm-1. The line positions at 5 and 10 mbar were measured with sub-MHz accuracy (460 and 260 kHz, respectively). After correction of the line pressure-shift, the frequency at zero pressure of the S(2) transition of the first overtone band was determined to be 187 104 299.51 ± 0.50 MHz. This value agrees within 1.7 MHz with the frequency obtained from the best available ab initio calculations and corresponds to only 15% of the claimed theoretical uncertainty.

  14. Diode pumping of Nd:ASL and its frequency doubling for blue emission around 450 nm

    OpenAIRE

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

    2008-01-01

    International audience We present the diode pumping of a Nd-doped strontium and lanthanum (Nd:ASL) crystal Sr1-xLax-yNdyMgxAl12-xO19 (0.05 ≤ x ≤ 0.5; y = 0.05) for second harmonic generation around 450 nm. In order to fulfill the pumping requirements of this crystal, we have developed a high-brightness pump source based on a tapered amplifier in an extended cavity with a volume Bragg grating for wavelength stabilization. A pump brightness of 110 MW.cm-2sr-1 has been obtained with a linewid...

  15. 130-W picosecond green laser based on a frequency-doubled hybrid cryogenic Yb:YAG amplifier.

    Science.gov (United States)

    Hong, Kyung-Han; Lai, Chien-Jen; Siddiqui, Aleem; Kärtner, Franz X

    2009-09-14

    130-W average-power picosecond green laser pulses at 514.5 nm are generated from a frequency-doubled hybrid cryogenic Yb:YAG laser. A second-harmonic conversion efficiency of 54% is achieved with a 15-mm-long noncritically phase-matched lithium triborate (LBO) crystal from a 240-W 8-ps 78-MHz pulse train at 1029 nm. The high-average-power hybrid laser system consists of a picosecond fiber chirped-pulse amplification seed source and a cryogenically-cooled double-pass Yb:YAG amplifier. The M(2) value of 2.7, measured at 77 W of second-harmonic power, demonstrates a good focusing quality. A thermal analysis shows that the longitudinal temperature gradient can be the main limiting factor in the second-harmonic efficiency. To our best knowledge, this is the highest-average-power green laser source generating picosecond pulses. PMID:19770908

  16. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    Science.gov (United States)

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  17. 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.

  18. A high gradient test of a single-cell superconducting radio frequency cavity with a feedback waveguide

    Science.gov (United States)

    Kostin, Roman; Avrakhov, Pavel; Kanareykin, Alexei; Solyak, Nikolay; Yakovlev, Vyacheslav; Kazakov, Sergey; Wu, Genfa; Khabiboulline, Timergali; Rowe, Allan; Rathke, John

    2015-09-01

    The most severe problem of the international linear collider (ILC-type) is its high cost, resulting in part from the enormous length of the collider. This length is determined mainly by the achievable accelerating gradient in the RF system of the collider. In current technology, the maximum acceleration gradient in superconducting (SC) structures is determined mainly by the value of the surface RF magnetic field. In order to increase the gradient, a superconducting traveling wave accelerating (STWA) structure is suggested. Utilization of STWA structure with small phase advance per cell for future high energy linear colliders such as ILCs may provide an accelerating gradient 1.2-1.4 times larger [1] than a standing wave structure. However, STWA structure requires a feedback waveguide for power redirecting from the end of the structure back to the front end of accelerating structure. Recent tests of a 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient of a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper, high gradient test results are presented.

  19. A Compact 532-nm Source by Frequency Doubling of a Diode Stack End-Pumped Nd:YAG Slab Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-Li; LIU Xiao-Meng; LI Dai-Jun; SHI Peng; Alex Schell; Claus Rüdige Haas; Du Ke-Ming

    2007-01-01

    A near-diffraction-limited green source is generated at 1 kHz repetition rate by frequency doubling ofa diode stack end-pumped electro-optically Q-switched Nd:YAG slab laser. We obtain 9.7mJ green light with pulse width of 12.2ns at a repetition rates of 1 kHz. The pump to green optical conversion efficiency is 12.9%. The energy pulse stability at 532nm is about 0.8%.

  20. A Frequency-Domain Adaptive Filter (FDAF) Prediction Error Method (PEM) Framework for Double-Talk-Robust Acoustic Echo Cancellation

    DEFF Research Database (Denmark)

    Gil-Cacho, Jose M.; van Waterschoot, Toon; Moonen, Marc;

    2014-01-01

    In this paper, we propose a new framework to tackle the double-talk (DT) problem in acoustic echo cancellation (AEC). It is based on a frequency-domain adaptive filter (FDAF) implementation of the so-called prediction error method adaptive filtering using row operations (PEM-AFROW) leading...... to the FDAF-PEM-AFROW algorithm. We show that FDAF-PEM-AFROW is by construction related to the best linear unbiased estimate (BLUE) of the echo path. We depart from this framework to show an improvement in performance with respect to other adaptive filters minimizing the BLUE criterion, namely the PEM...

  1. Multi-mJ bursts of green light obtained by frequency doubling the output of a fiber based MOPA

    Science.gov (United States)

    Rowen, Eitan E.; Shalev, Nir; Tal, Eran; Lasri, Kobi; Inbar, Eran

    2016-03-01

    We demonstrate a fiber laser that generates bursts of 70-300 pulses at a frequency of 2-8 MHz with over 4 mJ of energy per burst at a wavelength of 532 nm. The output of an Yb-doped fiber amplifier chain is doubled in a single pass through an LBO crystal with efficiency of above 65%. A seed-diode generates the pulse train, which is amplified to a peak power that allows efficient SHG. Such a solution may have many industrial and other applications, where fiber-based solutions have many advantages, but suffer a disadvantage of relatively low pulse energy.

  2. LD-pumped Nd:YVO sub 4 frequency-doubled by CPM LBO laser at 671 nm

    CERN Document Server

    Zheng Quan; Qian Long Sheng; Zhao Ling

    2001-01-01

    A design of LD-pumped high efficient Nd:YVO sub 4 /LBO red laser is reported. Using critical phase-matching LBO for the first time, 671 nm red laser is obtained by 1.342 mu m intracavity frequency doubling. With 800 mW incident pump laser, 52 mW and 97 mW TEM00 mode red laser output are obtained by II-typed and I-typed LBO. The optical-to-optical conversions are up to 6.5% and 12.1% respectively

  3. 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.

  4. Frequency Up- and Down-conversions in Two-mode Cavity%两模腔中的参量上转换和下转换

    Institute of Scientific and Technical Information of China (English)

    李斌; 冯勋立; 张智明

    2011-01-01

    提出了一种通过建立双线性二次哈密顿量在量子腔中实现参量上转换和下转换的方案.通常在非线性过程中,介质本身不参与能量的净交换,但光波频率可以发生转换的作用称为参量转换作用.此方案建立在一个四能级原子同时与两经典场和两量子场相互作用的基础上,理论属于非线性光学四波混频范畴.将原子制备在合适的能级上,经典光场与相应的能级发生共振,而同时量子光场与相应的能级产生大失谐相互作用,在强相互作用区域内,原子和腔场失耦合,进而实现腔模的参量转换.根据所制备初始能级的不同以及光场激发能级的差异,分别实现了参量上转换和参量下转换.在利用参量下转换制备压缩算符后,对实验的可行性进行了讨论,并且给出了理论值.结果表明:在级联三能原子中采用一个级联双光子过程代替了原来的两个偶极禁戒跃迁间的经典驱动,可以保证高的不同频率之间的转换效率,并且用于光的量子操控和量子信息处理.%A scheme was proposed to construct bilinear and quadratic Hamiltonians for frequency up-and down-conversions in cavity quantum electrodynamics (QED).Generally,in nonlinear optics,the interaction that the energe swaps between different optic modes without atomic transition is named frequency conversion.The proposed scheme was based on the interactions of a single four-level atom simultaneously with two classical driving fields and a two-mode cavity field,which is in the domain of four-wave mixing.By initially preparing the atom in a suitable state,each pump light was resonant with its transition,and two quantum modes were large tune to the other two transition,respectively,In the strong laser regime,the atomic degrees of freedom could be decoupled from the cavity degrees of freedom and the frequency conversion could be realized for the cavity modes.Due to the different initial states and

  5. Green Output of 1.5 W from a Diode-Pumped Intracavity Frequency-Doubled Self-Q-Switched and Mode-Locked Cr,Nd:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    DU Shi-Feng; WANG Su-Mei; ZHANG Dong-Xiang; LI De-Hua; ZHANG Zhi-Guo; FENG Bao-Hua; ZHANG Shi-Wen

    2007-01-01

    We report a diode-pumped intracavity frequency-doubled self-Q-switched and mode-locked Cr,Nd:YAG/KTP green laser with a Z-type cavity, which produces 1.5 W of average power at 532 nm with incident pump power 14.2 W. The individual mode-locked green pulse duration is about 560ps with 149MHz repetition rate. Almost 100% modulation depth of the mode-locked green pulses is achieved at an incident pump power of 4.13 W. The maximum energy of Q-switched green pulse is 19.8 fiJ. The experimental results of pulse duration and pulse energy of Q-switched green pulse agree well with the theoretical calculations.

  6. Frequency of Iatrogenic damage to adjacent tooth during class II cavity preparation among dental students at Tehran University of Medical Sciences in 2010

    Directory of Open Access Journals (Sweden)

    Reza Yazdani

    2013-08-01

    Full Text Available   Background and Aims: Iatrogenic damage to adjacent tooth during proximal cavity preparation is one of the most common side effects in operative dentistry. The aim of this study was to determine prevalence of iatrogenic damages to adjacent tooth during the preparation of proximal Class II cavities among undergraduate students at dental faculty of Tehran University of Medical Sciences in 2010 .   Materials and Methods: 106 posterior permanent teeth which had Class II decay with sound proximal surfaces of adjacent teeth were selected and restored by dental students awarding the aims of the present study. After finishing restoration, proximal surfaces were completely dried by air and evaluated with dental chair light. In doubtful cases, surfaces were evaluated with × 3 magnification. Damages were classified into 2 groups; abrasion and groove. Data were analyzed using Fishers exact and Pearson chi square tests .   Results: The frequency of adjacent surfaces damage were 57.5%, with 31.1% damages as abrasion and 26.4% as groove. Students who used matrix band and wedge in proximal area as preventive instruments showed 53.4% damages and other students showed 57.3% damages (P>0.05. A significantly higher number of females and students at restorative course level (3 used wedge and matrix band than males and students at restorative course level (4 for protecting adjacent teeth (P<0.05.   Conclusion: According to the high percentage of iatrogenic damages on adjacent sound teeth in class II cavity preparation, teaching of preventive methods and using proper techniques is necessary for dental students as future dentists.

  7. Efficiency of non-linear frequency conversion of double-scale pico-femtosecond pulses of passively mode-locked fiber laser.

    Science.gov (United States)

    Smirnov, Sergey V; Kobtsev, Sergey M; Kukarin, Sergey V

    2014-01-13

    For the first time we report the results of both numerical simulation and experimental observation of second-harmonic generation as an example of non-linear frequency conversion of pulses generated by passively mode-locked fiber master oscillator in different regimes including conventional (stable) and double-scale (partially coherent and noise-like) ones. We show that non-linear frequency conversion efficiency of double-scale pulses is slightly higher than that of conventional picosecond laser pulses with the same energy and duration despite strong phase fluctuations of double-scale pulses. PMID:24515065

  8. The importance of oral hygiene on adults with the focus on preventive measures resulting in the reduction of oral cavity diseases frequency.

    OpenAIRE

    KÁPLOVÁ, Hana

    2015-01-01

    The Dissertation work presented herein monitors the significance of oral hygiene in adults, while aiming at preventive measures leading to lowering mouth cavity illness occurrences. Within the theoretical part, I focus on the delineation of important terms relating to preventive care for oral cavity, information concerning anatomy, physiology of oral cavity, influence of foods and other problems within the oral cavity, among which there are tooth cavities and diseases of gingiva. In the pract...

  9. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm

    Science.gov (United States)

    Saarinen, Esa J.; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G.

    2016-03-01

    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the laser a promising tool for medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  10. Electromagnetic SCRF Cavity Tuner

    Energy Technology Data Exchange (ETDEWEB)

    Kashikhin, V.; Borissov, E.; Foster, G.W.; Makulski, A.; Pischalnikov, Y.; Khabiboulline, T.; /Fermilab

    2009-05-01

    A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving {+-} 1 mm and producing a longitudinal force up to {+-} 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested.

  11. 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

  12. Analysis of a Triple-cavity Photonic Molecule Based on Coupled Mode Theory

    CERN Document Server

    Yang, Chao; Jiang, Xiaoshun; Xiao, Min

    2016-01-01

    In this paper, we analyze a chain-linked triple-cavity photonic molecule (TCPM) with controllable coupling strengths between the cavities on their spectral properties and field (energy) distributions by solving eigenvalues and eigenvectors of the Hamiltonian matrix based on coupled mode theory. Phase transition is extended from double-cavity photonic molecules (DCPMs) to TCPMs, and evolutions of the supermode frequencies and linewidths are analyzed, which have synchronous relations with the degree of coherence between adjacent optical microcavities and energy distributions in the three cavities, respectively. We develop a superposition picture for the three supermodes of the TCPM, as interferences between supermodes of sub-DCPMs. In particular, we demonstrate the abnormal properties of the central supermode in TCPMs, such as dark state in middle cavity and phase shift when energy flowing between side cavities, which are promising in information processing and remote control of energy. General properties of TC...

  13. First results of low frequency electromagnetic wave detector of TC-2/Double Star program

    Directory of Open Access Journals (Sweden)

    J. B. Cao

    2005-11-01

    Full Text Available LFEW is a low frequency electromagnetic wave detector mounted on TC-2, which can measure the magnetic fluctuation of low frequency electromagnetic waves. The frequency range is 8 Hz to 10 kHz. LFEW comprises a boom-mounted, three-axis search coil magnetometer, a preamplifier and an electronics box that houses a Digital Spectrum Analyzer. LFEW was calibrated at Chambon-la-Forêt in France. The ground calibration results show that the performance of LFEW is similar to that of STAFF on TC-1. The first results of LFEW show that it works normally on board, and that the AC magnetic interference of the satellite platform is very small. In the plasmasphere, LFEW observed the ion cyclotron waves. During the geomagnetic storm on 8 November 2004, LFEW observed a wave burst associated with the oxygen ion cyclotron waves. This observation shows that during geomagnetic storms, the oxygen ions are very active in the inner magnetosphere. Outside the plasmasphere, LFEW observed the chorus on 3 November 2004. LFEW also observed the plasmaspheric hiss and mid-latitude hiss both in the Southern Hemisphere and Northern Hemisphere on 8 November 2004. The hiss in the Southern Hemisphere may be the reflected waves of the hiss in the Northern Hemisphere.

  14. 一种双腔体二甲基硅氧烷液体变焦透镜%Tunable liquid lens with double PDMS cavities produced by diamond turning and soft lithography

    Institute of Scientific and Technical Information of China (English)

    康竞然; 陈海清; 谭佐军; 梁庆文

    2011-01-01

    In conventional PDMS(polydimethylsiloxane) tunable liquid lens,the edge of the deformed membrane often falls off the cavity.Thus,an improved model for tunable liquid lens with double cavities was proposed.A convenient and low-cost process was used to fabricate the lens that combined single-point diamond turning(SPDT) with soft lithography using PDMS.Compared with the normal structures,the new one with double cavities reserve the tunable focus function,and can promise a safer bonding between the lens cavity and the PDMS membrane.Experimental results demonstrate that the lens proposed is more stable than the normal single cavity liquid lens.%针对PDMS(二甲基硅氧烷)液体变焦透镜在使用过程中常会发生边缘脱落从而影响透镜性能甚至毁坏整个器件的问题,提出了一种基于单点金刚石切削和软刻蚀工艺的双腔体可调焦透镜模型,该模型相比仅由单PDMS腔体和PDMS薄膜粘合的结构,能有效防止在大变形条件下变形膜边缘脱落,从而更大可能地保证透镜正常工作.测试结果表明:相比于单腔体的模型,该透镜在保留可调焦透镜性能的同时,具有更好的工作稳定性.

  15. Analysis of the natural frequency of a quartz double-end tuning fork with a new deformation model

    Science.gov (United States)

    Huang, Bo-Shiun; Chang-Chien, Wen-Tien; Hsieh, Fa-Hwa; Chou, Yuan-Fang; Chang, Chia-Ou

    2016-06-01

    The quartz double-end tuning fork is composed of two parallel slender beams with their ends fixed to the proof masses, both ends of which are clamped. The structure is made of a quartz wafer which is anisotropic in stiffness. In anti-phase mode the two slender parallel beams vibrate in opposite directions and can be modelled as an Euler beam. The twist moments caused by the slender beams on the proof mass make the cross-section of the proof mass deform into a warped surface. The objective of this research is to establish the warping deformation model so that we can build up the equation of motion for anisotropic stiffness by using Hamilton’s principle and then perform theoretical analysis. The more realistic warping displacement leads the natural frequency closer to the true one. The purpose of the proof mass is to modulate the frequencies and mode shape of tuning fork beams. The advantage of anti-phase mode is that the centre of mass in unchanged during motion so that the system has a higher signal-to-noise ratio. The theoretically obtained frequency is compared with the experimental one and that obtained by the finite element method.

  16. Design of Frequency Selective Surface with Double Bands%双带频率选择表面设计

    Institute of Scientific and Technical Information of China (English)

    曲宝龙; 李旭东; 朱鹏刚

    2012-01-01

    In order to realize double-band properties of frequency selective surface (FSS), the composite element FSS, composed of rectangle grid and three-ring loop element, is presented. The spectral domain solution method is described in detail for FSS. The frequency response properties of FSS are analyzed for electromagnetic waves with different incident angles and polarizations based on the spectral domain method. The result shows that the designed FSS can maintain stable double-band, flat top transmission and sharp skirt properties for electromagnetic waves with different incidence angles and polarizations. The double-band properties show stop-band from 1. 8 GHz to 5.4 GHz and pass-band from 5.4 GHz to 20.0 GHz. The resonant frequency of stop-band is situated at about 3. 1 GHz, and the bandwidth of flat top transmission is over 14.3 GHz at —4 dB. The sharp skirt properties show that the S-band signal is reflected intensively and other band signals are transmitted, and multi-band communication is achieved. The composite FSS can be used in satellite communications, radomes and other fields.%为了实现频率选择表面(FSS)的双带特性,设计了由矩形栅格和三圆环组合单元FSS.对FSS的谱域求解方法进行了详细的描述.采用谱域法分析了不同角度和极化入射波下FSS的频率响应性能.结果表明,所设计的FSS对于不同入射角度和极化电磁波具有稳定的双带、平顶传输及陡峭下降边缘特性.双带特性大致表现为1.8~5.4 GHz的阻带和5.4~20.0 GHz的通带.阻带谐振频率稳定在3.1 GHz左右,而通带在-4 dB的平顶传输带宽达14.3 GHz以上.其陡峭下降边缘特性表现为S波段信号强烈反射,而其他波段信号通过,从而实现多波段通讯.该结构FSS可应用于卫星通信、雷达罩及其他相关领域.

  17. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    Science.gov (United States)

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system.

  18. A passively mode-locked intracavity frequency doubled Nd:YVO4 femtosecond green laser based on graphene

    Science.gov (United States)

    Shi, R. P.; Bai, Y.; Qi, M.; Chen, X. M.; Wei, H. D.; Ren, Z. Y.; Bai, J. T.

    2014-02-01

    By using an atmospheric-pressure chemical vapor deposition (APCVD) method with a C2H2 carbon source, seven-layer graphene films as saturable absorbers are fabricated and transferred to an anti-reflective mirror of 1064 nm wavelength range. Based on this transmission-type graphene saturable absorber mirror (GSAM), a continuous wave (CW) passively mode-locked femtosecond green laser is achieved by 808 nm laser diode (LD) end-pumped Nd:YVO4 crystal and type-I critical phase-matched LBO crystal intracavity frequency doubling for the first time. Stable ultrashort green laser pulses as short as 374 fs are measured with a repetition rate of 71.4 MHz and an average output power of 117 mW at a central wavelength of 531.7 nm.

  19. Employing SiO_2 Buffer Layer to Improve Adhesion of the Frequency-doubled Antireflection Coating on LBO

    Institute of Scientific and Technical Information of China (English)

    TAN Tianya; SHAN Jing; WU Wei; GUO Yongxin; SHAO Jianda; FAN Zhengxiu

    2009-01-01

    Frequency-doubled antireflection coatings simultaneously effective at 1064 nm and 532 nm were deposited on the lithium triborate(LiB_3O_5 or LBO)crystals using the electron beam evaporation method.Comparing with the sample without buffer layer,it is found that the adhesion of the sample with buffer layer of SiO_2 between coating and LBO substrate is improved significantly from 137.4 mN to greater than 200 mN.And the laser-induced damage threshold is increased by 20% from 15.1 J/cm~2 to 18.6 J/cm~2 .The strengthening mechanism of adhesion of the buffer layer of SiO_2 is discussed by considering full plastic indentation and shear theory.

  20. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    Science.gov (United States)

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system. PMID:18273287

  1. Verb-noun double dissociation in aphasic lexical impairments: the role of word frequency and imageability.

    Science.gov (United States)

    Luzzatti, Claudio; Raggi, Rossella; Zonca, Giusy; Pistarini, Caterina; Contardi, Antonella; Pinna, Gian-Domenico

    2002-01-01

    Neurolinguistic studies have provided important evidence regarding the organization of lexical representations and the structure of underlying conceptual knowledge; in particular, it has been shown that the retrieval of verbs and nouns can be damaged selectively. Dissociated lexical damage is proof of an independent mental organization of lexical representations and/or of the underlying processes. The aim of the present study is to estimate the rate of dissociated impairments for nouns and verbs on a large sample of mild to moderate aphasic patients and to investigate the mechanisms underlying such phenomena. In addition, the authors wished to verify to what degree the impairment for nouns and verbs is related to a specific type of language disorder. A confrontation naming task for verbs and nouns was administered to 58 aphasic patients. The major lexical (word frequency and age of acquisition) and semantic variables (familiarity and imageability of the underlying concept) were considered for each noun and verb used in the task. Verbs were distinguished by major functional classes (transitive, intransitive, and ergative verbs). The data collected from this task were analyzed twice: (i) as a group study comparison of major aphasic subgroups and (ii) as a multiple single case study to evaluate the differences on the naming of verbs and nouns and the effect of the lexical semantic variables on each individual patient. The results confirm the existence of dissociated naming impairments of verbs and nouns. Selective impairment of verbs is more frequent (34%) than that of nouns (10%). In many cases, the dissociated pattern of naming impairment disappeared when the effect of the concomitant variables (word frequency and imageability) was removed, but in approximately one-fifth of the cases the noun or verb superiority was preserved. Noun superiority emerged in five of six agrammatic patients. Both the naming of verbs (n = 9) or of nouns (n = 6) could be impaired

  2. Microfabricated ion frequency standard

    Science.gov (United States)

    Schwindt, Peter; Biedermann, Grant; Blain, Matthew G.; Stick, Daniel L.; Serkland, Darwin K.; Olsson, III, Roy H.

    2010-12-28

    A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

  3. Tunable continuous-wave dual-wavelength laser by external-cavity superluminescent diode with a volume Bragg grating and a diffraction grating

    Science.gov (United States)

    Zheng, Yujin; Kurita, Takashi; Sekine, Takashi; Kato, Yoshinori; Kawashima, Toshiyuki

    2016-10-01

    We demonstrate the tunable continuous-wave dual-wavelength laser based on a double external-cavity superluminescent diode (SLD). The double external cavity consisted of a volume Bragg grating (VBG) and a diffraction grating bracketing the SLD's two facets. The VBG was used as an output coupler to enable the external-cavity SLD to achieve a stable wavelength. A narrow bandwidth of 0.25 nm was achieved in single-wavelength operation. The diffraction grating served as an end mirror to create another tunable wavelength external cavity for the SLD. A wavelength tuning range of 23 nm was achieved. The laser output of the double external-cavity SLD had a tunable spectral separation with dual-wavelengths from +6.42 to -16.94 nm. An output power of up to 37.7 mW was achieved with a frequency difference of 7.1 THz.

  4. Observation of Self-Frequency Doubling in Diode-Pumped Mode-Locked Nd-Doped La3Ga5SiO14 Laser

    Science.gov (United States)

    Liu, Jia-Xing; Wang, Zhao-Hua; Tian, Wen-Long; Wang, Qing; Zhang, Zhi-Guo; Wei, Zhi-Yi; Yu, Hao-Hai; Zhang, Huai-Jin; Wang, Ji-Yang

    2015-01-01

    A diode-pumped passively mode-locked Nd-doped La3Ga5SiO14 (Nd:LGS) laser is realized by using a semiconductor saturable absorber mirror. With the pump power of 2 W, we obtain a 532 nm self-frequency doubling (SFD) laser together with a 10.9 ps fundamental laser at the repetition rate of 173.7 MHz. To the best of our knowledge, it is the first time for self-frequency doubling in the diode-pumped mode-locked Nd:LGS laser. Benefited from the diode lasers and its self-frequency doubling property, Nd:LGS could be a potential candidate for compact, stable and cheap ultrafast green laser sources.

  5. Injection-locking of two frequency-doubled lasers with 3.2 GHz offset for driving Raman transitions with low photon scattering in $^{43}$Ca$^+$

    CERN Document Server

    Linke, N M; Lucas, D M

    2013-01-01

    We describe the injection locking of two infrared (794 nm) laser diodes which are each part of a frequency doubled laser system. An acousto-optic modulator (AOM) in the injection path gives an offset of 1.6 GHz between the lasers for driving Raman transitions between states in the hyperfine split (by 3.2 GHz) ground level of $^{43}$Ca$^+$. The offset can be disabled for use in $^{40}$Ca$^+$. We measure the relative linewidth of the frequency-doubled beams to be 42 mHz in an optical heterodyne measurement. The use of both injection locking and frequency doubling combines spectral purity with high optical power. Our scheme is applicable for providing Raman beams across other ion species and neutral atoms where coherent optical manipulation is required.

  6. All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

    Science.gov (United States)

    Zhu, P. F.; Li, B.; Liu, W. Q.; Liu, T. H.; Fang, C. X.; Zhao, Y.; Zheng, Q.

    2012-11-01

    An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.

  7. All-solid-state continuous-wave frequency-doubling Nd:YVO(4)/LBO laser with 2.35 W output power at 543 nm.

    Science.gov (United States)

    Yao, Yi; Zheng, Quan; Qu, Dapeng; Gong, Xiangyu; Zhou, Kai; Liu, Yang; Zhao, Ling

    2009-12-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a cw diode-pumped Nd:YVO(4) laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 14.5 W of diode pump power and the frequency-doubling crystal LiB(3)O(5), as high as 2.35 W of cw output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 15.7%; the output power stability over 5 h is better than 2.56%. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by intracavity frequency doubling of a diode pumped Nd:YVO(4) laser at 1086 nm. PMID:19953186

  8. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

    Science.gov (United States)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-02-01

    An efficient and compact red laser at 458 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 916 nm under the condition of suppression the higher gain transition near 1064 nm. With 30 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 458 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 32.0% and the output power stability in 8 hours is better than 2.35%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 458 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 916 nm.

  9. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 672 nm

    Science.gov (United States)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2012-12-01

    An efficient and compact red laser at 672 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 1344 nm under the condition of suppression the higher gain transition near 1064 nm. With 38 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 672 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 25.3% and the output power stability in 8 h is better than 2.38%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 672 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1344 nm.

  10. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 2.17 W output power at 543 nm

    Science.gov (United States)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-03-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a CW diode-pumped Nd:LuVO4 laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 16 W of diode pump power and the frequency-doubling crystal LBO, as high as 2.17 W of CW output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 13.6% and the output power stability over 8 hours is better than 2.86%. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1086 nm.

  11. Radiation-induced DNA double-strand break frequencies in human squamous cell carcinoma cell lines of different radiation sensitivities

    International Nuclear Information System (INIS)

    DNA neutral (pH 9-6) filter elution was used to measure radiation-induced DNA double-strand break (dsb) frequencies in eight human squamous cell carcinoma cell lines with radiosensitivities (D0) ranging from 1.07 to 2.66 Gy and D-bar values ranging from 1.46 to 4.08 Gy. Elution profiles of unirradiated samples from more radiosensitive cell lines were all steeper in slope than profiles from resistant cells. The shapes of the dsb induction curves were curvilinear and there was some variability from cell line to cell line in the dose-response for the induction of DNA dsb after exposures to 5-100 Gy 60Co γ-rays. There was no relation between shapes of survival curves and shapes of the dose-responses for the induction of DNA dsb. At low doses (5-25 Gy), three out of four of the more sensitive cell lines (D-bar3.0 Gy). Although the low-dose (5-25 Gy) elution results were variable, they suggest that DNA neutral elution will detect differences between sensitive and resistant tumour cells in initial DNA dsb frequencies. (author)

  12. Double-gated Si NW FET sensors: Low-frequency noise and photoelectric properties

    Science.gov (United States)

    Gasparyan, F.; Khondkaryan, H.; Arakelyan, A.; Zadorozhnyi, I.; Pud, S.; Vitusevich, S.

    2016-08-01

    The transport, noise, and photosensitivity properties of an array of silicon nanowire (NW) p+-p-p+ field-effect transistors (FETs) are investigated. The peculiarities of photosensitivity and detectivity are analyzed over a wide spectrum range. The absorbance of p-Si NW shifts to the short wavelength region compared with bulk Si. The photocurrent and photosensitivity reach increased values in the UV range of the spectrum at 300 K. It is shown that sensitivity values can be tuned by the drain-source voltage and may reach record values of up to 2-4 A/W at a wavelength of 300 nm at room temperature. Low-frequency noise studies allow calculating the photodetectivity values, which increase with decreasing wavelength down to 300 nm. We show that the drain current of Si NW biochemical sensors substantially depends on pH value and the signal-to-noise ratio reaches the high value of 105. Increasing pH sensitivity with gate voltage is revealed for certain source-drain currents of pH-sensors based on Si NW FETs. The noise characteristic index decreases from 1.1 to 0.7 with the growth of the liquid gate voltage. Noise behavior is successfully explained in the framework of the correlated number-mobility unified fluctuation model. pH sensitivity increases as a result of the increase in liquid gate voltage, thus giving the opportunity to measure very low proton concentrations in the electrolyte medium at certain values of the liquid gate voltage.

  13. 56W frequency doubled source at 530 nm pumped by a single-mode single-polarization picosecond Yb3+-doped fiber MOPA

    OpenAIRE

    Chen, Kang Kang; Alam, S. -U.; Hayes, J R; Baker, H. J.; Hall, D W; McBride, R; Price, J.H.V.; Lin, D.; Malinowski, A.; Richardson, D J

    2010-01-01

    We report a frequency doubled green source at 530nm pumped based on an all-fiber, picosecond, single polarization Yb3+-doped fiber MOPA delivering 20ps pulses at user selectable repetition rates of up to 910MHz and an average output power in excess of 100W at 1.06?m. The output of the MOPA was frequency doubled using a LBO crystal. Up to 56 W of green light was generated at a corresponding repetition rate of 227 MHz at an overall conversion efficiency of 56%. The diode-to-green optical power ...

  14. 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.

  15. AIR FLOW AND ENVIRONMENTAL WIND VISUALIZATION USING A CW DIODE PUMPED FREQUENCY DOUBLED Nd:YAG Laser

    Directory of Open Access Journals (Sweden)

    Mircea UDREA

    2009-09-01

    Full Text Available Preliminary results obtained in developing a visualisation technique for non-invasive analysis of air flow inside INCAS subsonic wind tunnel and its appendages are presented. The visualisation technique is based on using a green light sheet generated by a continuous wave (cw longitudinally diode pumped and frequency doubled Nd:YAG laser. The output laser beam is expanded on one direction and collimated on rectangular direction. The system is tailored to the requirements of qualitative analysis and vortex tracking requirements inside the INCAS 2.5m x 2.0m subsonic wind tunnel test section, for measurements performed on aircraft models. Also the developed laser techniques is used for non-invasive air flow field analysis into environmental facilities settling room (air flow calming area. Quantitative analysis is enabled using special image processing tools upon movies and pictures obtained during the experiments. The basic experimental layout in the wind tunnel takes advantage of information obtained from the investigation of various aircraft models using the developed visualisation technique. These results are further developed using a Particle Imaging Velocimetry (PIV experimental technique.The focus is on visualisation techniques to be used for wind flow characterization at different altitudes in indus-trial and civil buildings areas using a light sheet generated by a Nd:YAG cw pumped and doubled laser at 532 nm wave-length. The results are important for prevention of biological/chemical disasters such as spreading of extremely toxic pol-lutants due to wind. Numerical simulations of wind flow and experimental visualisation results are compared. A good agreement between these results is observed.

  16. Modulated Pulse Generations in a Laser-diode-pumped Passively Q-switched Intracavity-frequency-doubling Nd∶YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    郑加安; 赵圣之; 陈磊

    2002-01-01

    The investigative results of modulated pulse output from an LD end-pumped passively Q-switched intracavity-frequency-doubling Nd∶YVO4/KTP laser with Cr4+∶YAG saturable absorber are presented. The numerical stimulations of these modulated pulses are carried out basing on the rate equations. It indicated that the modulations are attribute to the frequency beating of two eigenstates of the resonant polarized modes. The theoretical calculations are in good agreement with the experimental observations.

  17. Simultaneous frequency stabilization and high-power dense wavelength division multiplexing (HP-DWDM) using an external cavity based on volume Bragg gratings (VBGs)

    Science.gov (United States)

    Hengesbach, Stefan; Klein, Sarah; Holly, Carlo; Witte, Ulrich; Traub, Martin; Hoffmann, Dieter

    2016-03-01

    Multiplexing technologies enable the development of high-brightness diode lasers for direct industrial applications. We present a High-Power Dense Wavelength Division Multiplexer (HP-DWDM) with an average channel spacing of 1.7 (1.5) nm and a subsequent external cavity mirror to provide feedback for frequency stabilization and multiplexing in one step. The "self-optimizing" multiplexing unit consists of four reflective Volume Bragg Gratings (VBGs) with 99% diffraction efficiency and seven dielectric mirrors to overlay the radiation of five input channels with an adjustable channel spacing of 1-2 nm. In detail, we focus on the analysis of the overall optical efficiency, the change of the beam parameter product and the spectral width. The performance is demonstrated using five 90 μm multimode 9xx single emitters with M2angular intensity distribution changes strongly and the beam parameter product decreases by a factor of 1.2 to 1.9. Thereby the angular intensity distribution is more affected than the width of the beam waist. The spectral width per emitter decreases to 3-200 pm (FWHM) depending on the injection current and the reflectance of the feedback mirror (0.75%, 1.5%, 4%, 6% or 8%). The overall optical multiplexing efficiency ranges between 77% and 86%. With some modifications (e.g. enhanced AR-coatings) we expect 90-95%.

  18. A novel CW yellow light generated by a diode-end-pumped intra-cavity frequency mixed Nd:YVO4 laser

    Science.gov (United States)

    Li, Bin; Yao, Jian Quan; Ding, Xin; Sheng, Quan; Yin, Sujia; Shi, Chunpeng; Li, Xue; Yu, Xuanyi; Sun, Bing

    2014-03-01

    We report an efficient continuous-wave (CW) yellow beam based on a Nd:YVO4 laser with a dual-wavelength wave plate, which is a full-wave plate at 1342 nm and a quarter-wave plate at 1064 nm. By inserting the dual-wavelength wave plate into the laser cavity and tuning the fast axis angle, based on the polarized property emission of Nd:YVO4, two simultaneous wavelengths of 1064 nm and 1342 nm were achieved. A LiB3O5 (LBO) crystal that is cut for critical type I phase matching at room temperature is used for summing frequency generation (SFG) of the laser. At an incident pump power of 5 W, a maximum CW output of 224 mW was obtained for a yellow laser with a wavelength of 593.5 nm and an optical-to-optical efficiency of 4.48%. To the best of our knowledge, this is the first time that a dual-wavelength wave plate has been used to realize a Nd:YVO4 yellow laser output.

  19. 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.

  20. Reconstructing rice phenology curves with frequency-based analysis and multi-temporal NDVI in double-cropping area in Jiangsu, China

    Science.gov (United States)

    Wang, Hongshuo; Lin, Hui; Munroe, Darla K.; Zhang, Xiaodong; Liu, Pengfei

    2016-06-01

    Crop phenology retrieval in the double-cropping area of China is of great significance in crop yield estimation and water management under the influences of global change. In this study, rice phenology in Jiangsu Province, China was extracted from multi-temporal MODIS NDVI using frequency-based analysis. Pure MODIS pixels of rice were selected with the help of TM images. Discrete Fourier Transformation (DFT), Discrete Wavelet Transformation (DWT), and Empirical Mode Decomposition (EMD) were performed to decompose time series into components of different frequencies. Rice phenology in the double-cropping area is mainly located on the last 2 IMFs of EMD and the first 2‒3 frequencies of DFT and DWT. Compared with DFT and DWT, EMD is limited to fewer frequencies. Multi-temporal MODIS NDVI data combined with frequency-based analysis can retrieve rice phenology dates with on average 79% valid estimates. The sorting result for effective estimations from different methods is DWT (85%)>EMD (80%)>DFT (74%). Planting date (88%) is easier to estimate than harvesting date (70%). Rice planting date is easily affected by the former cropping mode within the same year in a double-cropping region. This study sheds light on understanding crop phenology dynamics in the frequency domain of multi-temporal MODIS data.

  1. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika;

    2011-01-01

    For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W...

  2. Multifocal and pattern-reversal visual evoked potentials vs. automated perimetry frequency-doubling technology matrix in optic neuritis

    Directory of Open Access Journals (Sweden)

    Marcella Nebbioso

    2013-01-01

    Full Text Available Background: To compare the usefulness of the traditional pattern-reversal Visual Evoked Potentials (VEP with multifocal VEP (mfVEP and Frequency-Doubling Technology (FDT perimetry in the evaluation of the ocular abnormalities induced by acute or subacute optic neuritis (ON. Materials and Methods: The test results of 24 ON patients were compared with those obtained in 40 normal control subjects. MfVEP recordings were obtained by using an Optoelectronic Stimulator that extracts topographic VEP using a pseudorandom m-sequence stimulus. Receiver operator characteristic (ROC curves were calculated to determine the sensitivity and specificity of abnormal values. Results: The frequency of the abnormal ocular findings differed in the ON patients according to the used technique. Reduced visual sensitivity was demonstrated in 12 eyes (54.5% using FDT perimetry; 17 eyes (77.2% showed decreased amplitude and/or an increase in the implicit time of the P1 wave in mfVEP and 20 eyes (90.9% showed an abnormal decrease in the amplitude and/or an increase in the latency of the P100 peak at VEP examination. The areas under the ROC curves ranged from 0.743 to 0.935, with VEP having the largest areas. The VEP and mfVEP amplitudes and latencies yielded the greatest sensitivity and specificity. Conclusions: The mfVEP and the FDT perimetry can be used for the evaluation and monitoring of visual impairment in patients with ON. The most sensitive and practical diagnostic tool in patients with ON is, however, the traditional VEP. The mfVEP can be utilized in those cases with doubtful or negative VEP results.

  3. Study on Frequency Doubling Scattering and Second—Order Scattering Spectra of Heparin—Methylene Blue System

    Institute of Scientific and Technical Information of China (English)

    刘绍璞; 罗红群; 李念兵; 刘忠芳

    2003-01-01

    Binding of heparin with methylene blue(MB) in pH5.7 Britton-Robinson buffer can result in a significant enhancement of frequency doubling scattering (FDS) and second-order scattering (SOS).Their maximum scattering wavelengths(λmax) appear at 350nm for FDS and 700nm for SOS,respectively.The optimum conditions of the reaction,the influencing factors and the relationship between the two scattering intensities and the concentration of heparin have been investigated.The new methods for the determination of trace amounts of heparin bassed on the FDS and SOS methods have been developed,which exhibit high sensitivities.The detection limits of heparin are 4.36ng/mL for the FDS method and 3.55ng/mL for the SOS method,respectively.Both of the methods have fairly godd selectivity and ware applied to the determination of heparin in sodium heparinate injection samples with satisfactory results.Moreover,the relative mechamisms have also been discussed.

  4. Cooperative Transmission in Mobile Wireless Sensor Networks with Multiple Carrier Frequency Offsets: A Double-Differential Approach

    Directory of Open Access Journals (Sweden)

    Kun Zhao

    2014-01-01

    Full Text Available As a result of the rapidly increasing mobility of sensor nodes, mobile wireless sensor networks (MWSNs would be subject to multiple carrier frequency offsets (MCFOs, which result in time-varying channels and drastically degrade the network performance. To enhance the performance of such MWSNs, we propose a relay selection (RS based double-differential (DD cooperative transmission scheme, termed RSDDCT, in which the best relay sensor node is selected to forward the source sensor node’s signals to the destination sensor node with the detect-and-forward (DetF protocol. Assuming a Rayleigh fading environment, first, exact closed-form expressions for the outage probability and average bit error rate (BER of the RSDDCT scheme are derived. Then, simple and informative asymptotic outage probability and average BER expressions at the large signal-to-noise ratio (SNR regime are presented, which reveal that the RSDDCT scheme can achieve full diversity. Furthermore, the optimum power allocation strategy in terms of minimizing the average BER is investigated, and simple analytical solutions are obtained. Simulation results demonstrate that the proposed RSDDCT scheme can achieve excellent performance over fading channels in the presence of unknown random MCFOs. It is also shown that the proposed optimum power allocation strategy offers substantial average BER performance improvement over the equal power allocation strategy.

  5. Second-order Scattering and Frequency Doubling Scattering Spectra of Thallium(III)-Methotrexate System and Its Analytical Application

    Institute of Scientific and Technical Information of China (English)

    XI Cun-Xian; LIU Zhong-Fang; HU Xiao-Li; LIU Shao-Pu; DUAN Hui

    2008-01-01

    In pH 4.9 Britton-Robinson buffer solution,methotrexate (MTX) reacted with thallium(III) to form a 3:1 che late.This resulted in great enhancement of second-order scattering (SOS) spectra and frequency doubling scattering (FDS) spectra and appearance of new SOS and FDS spectra.Their maximum wavelengths were located at 520 and 390 nm,respectively.The increments of scattering intensities (ΔI) were directly proportional to the concentrations of MTX in the ranges of 0.022--2.0 μg·mL-1 (SOS method) and 0.008--2.5μg·mL-1 (FDS method).The methods exhibited high sensitivities.The detection limits for MTX were 7.4 ng·mL-1 (SOS method) and 2.3 ng.mL-1 (FDS method),respectively.The optimum conditions of the reaction,the influencing factors and the effects of coexisting substances were investigated.A highly sensitive,simple and fast method for the determination of MTX has been developed.The method can be applied satisfactorily to the determination of MTX in human serum samples.In this work,the charge distribution of MTX was calculated by a CNDO quantum chemistry method.In addition,the reaction mechanism was discussed.

  6. Design and Operation of a Frequency Doubled Nd:YAG Thomson Scattering System with Transmission Grating ICCD Spectrometer

    Science.gov (United States)

    Schoenbeck, N. L.; Dowd, A. S.; Fonck, R. J.; Schlossberg, D. J.; Winz, G. R.

    2012-10-01

    A novel Thomson scattering system has been deployed on the Pegasus Toroidal Experiment. It provides a relatively low-cost, simplified design. Scattering is achieved using a 7 ns, 2 J frequency doubled Nd:YAG laser operating at 532 nm. The laser focuses to ˜3 mm diameter within the plasma via a 7 m beam-line. The beam-line contains cameras as beam finders and remotely adjustable mirrors for shot-to-shot alignment. A custom multi-element lens collects scattered photons from 15 cm 40%) image intensified CCD (ICCD) camera. Three spectrometers provide a total of 24 channels. Two interchangeable gratings exist to cover low (Te = 10--100 eV) and high (Te = 0.10--1 keV) electron temperature regimes on Pegasus. The spectrometer is optimized for ne from mid-10^18 to mid-10^19 m-3. The signal-to-noise expected is ˜0.5 of an equivalent system using Nd:YAG at 1064 nm and avalanche photodiode detectors.

  7. Frequency-dependent Study of Ultrapure Solid 4He by Using Rigid Double-pendulum Torsional Oscillator

    Science.gov (United States)

    Choi, Jaewon; Shin, Jaeho; Kim, Eunseong

    2015-03-01

    The physical origin of the period drop found in the torsional oscillator (TO) containing solid 4He was previously interpreted as the appearance of supersolidity. The current consensus is that the increase in the shear modulus leads to the period anomaly. Further studies show that the stiffening effect in TO can be amplified if a TO is not properly designed to be ``rigid.'' In this study, we designed a rigid double-pendulum TO. High purity solid 4He sample (0.6ppb) was grown by the block capillary method. The resonant period of TO starts to decrease from the empty cell data at 80mK. The ratio of the resonant period changes to the total mass loading are 3 . 8 ×10-5 and 2 . 6 ×10-4 for 1st and 2nd mode, respectively. Unlike recent experiment, we could not found a frequency-independent period drop. The upper bound for the putative supersolid fraction is less than 4 ×10-6 . The dissipation peak accompanied with the period drop was also analyzed with Cole-Cole plot and ωτ plot. We conclude that major contribution for the anomalous TO responses comes from the elastic effect.

  8. One-shot and aberration-tolerable homodyne detection for holographic storage readout through double-frequency grating-based lateral shearing interferometry.

    Science.gov (United States)

    Yu, Yeh-Wei; Xiao, Shuai; Cheng, Chih-Yuan; Sun, Ching-Cherng

    2016-05-16

    A simple method to decode the stored phase signal of volume holographic data storage with adequate wave aberration tolerance is highly demanded. We proposed and demonstrated a one-shot scheme to decode a binary-phase encoding signal through double-frequency-grating based shearing interferometry (DFGSI). The lateral shearing amount is dependent on the focal length of the collimated lens and the frequency difference between the gratings. Diffracted waves with phase encoding were successfully decoded through experimentation. An optical model for the DFGSI was built to analyze phase-error induction and phase-difference control by shifting the double-frequency grating longitudinally and laterally, respectively. The optical model was demonstrated experimentally. Finally, a high aberration tolerance of the DFGSI was demonstrated using the optical model. PMID:27409865

  9. Focus: Two-dimensional electron-electron double resonance and molecular motions: The challenge of higher frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Franck, John M.; Chandrasekaran, Siddarth; Dzikovski, Boris; Dunnam, Curt R.; Freed, Jack H., E-mail: jhf3@cornell.edu [Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, New York 14853 (United States)

    2015-06-07

    The development, applications, and current challenges of the pulsed ESR technique of two-dimensional Electron-Electron Double Resonance (2D ELDOR) are described. This is a three-pulse technique akin to 2D Exchange Nuclear Magnetic Resonance, but involving electron spins, usually in the form of spin-probes or spin-labels. As a result, it required the extension to much higher frequencies, i.e., microwaves, and much faster time scales, with π/2 pulses in the 2-3 ns range. It has proven very useful for studying molecular dynamics in complex fluids, and spectral results can be explained by fitting theoretical models (also described) that provide a detailed analysis of the molecular dynamics and structure. We discuss concepts that also appear in other forms of 2D spectroscopy but emphasize the unique advantages and difficulties that are intrinsic to ESR. Advantages include the ability to tune the resonance frequency, in order to probe different motional ranges, while challenges include the high ratio of the detection dead time vs. the relaxation times. We review several important 2D ELDOR studies of molecular dynamics. (1) The results from a spin probe dissolved in a liquid crystal are followed throughout the isotropic → nematic → liquid-like smectic → solid-like smectic → crystalline phases as the temperature is reduced and are interpreted in terms of the slowly relaxing local structure model. Here, the labeled molecule is undergoing overall motion in the macroscopically aligned sample, as well as responding to local site fluctuations. (2) Several examples involving model phospholipid membranes are provided, including the dynamic structural characterization of the boundary lipid that coats a transmembrane peptide dimer. Additionally, subtle differences can be elicited for the phospholipid membrane phases: liquid disordered, liquid ordered, and gel, and the subtle effects upon the membrane, of antigen cross-linking of receptors on the surface of plasma membrane

  10. 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.

  11. 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

  12. Hydroforming of elliptical cavities

    Science.gov (United States)

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, P.

    2015-02-01

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV /m after buffered chemical polishing (BCP) and up to 42 MV /m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30 - 35 MV /m were measured after BCP and Eacc up to 40 MV /m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc=30 - 35 MV /m . One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have been

  13. Cavity magnomechanics

    Science.gov (United States)

    Zhang, Xufeng; Zou, Changling; Jiang, Liang; Tang, Hong X.

    Mechanical oscillators have been recently widely utilized to couple with optical and microwave photons in a variety of hybrid quantum systems, but they all lack the tunability. The magnetostrictive force provides an alternative mechanism to allow phonon to couple with a different type of information carrier-magnon, the collective excitation of magnetization whose frequency can be tuned by a bias magnetic field. Here, we demonstrate an intriguing hybrid system that consists of a magnonic, a mechanical, and a microwave resonator. The magnon-phonon interaction results in hallmark coherent phenomena such as magnomechanically induced transparency/absorption and magnomechanical parametric amplification. The magnetic field dependence of magnon provides our system with unprecedented tunability. Moreover, the great flexibility of our system allows us to achieve triple resonance among magnon, phonon and photon, which drastically enhances the magnomechanical interaction. Our work demonstrates the fundamental principle of cavity magnetomechanics, opening up great opportunities in various applications, such as tunable microwave filter and amplifier, long-lifetime quantum memories, microwave-to-optics conversion.

  14. DDS频率合成器的方波重影现象研究%Research on double shadow of square wave in DDS frequency synthesizer

    Institute of Scientific and Technical Information of China (English)

    李辉祥; 黄光明

    2014-01-01

    As the 3rd generation of frequency synthesis technology,direct digital frequency synthesis(DDS)is widely used in instrumentation,communication,radar and other fields. When a DDS-based frequency synthesizer outputs square wave,the waveform comes with double shadow obviously. The double shadow directly impacts the quality of the square wave. The reason of square wave double shadow occurs is analyzed. And an improved algorithm is proposed,which is suitable for FPGA. The new al-gorithm weakens the square wave double shadow effectively.%直接数字频率合成技术(DDS)作为第三代频率合成技术,广泛应用于仪器仪表、通信、雷达等领域。基于DDS技术设计的频率合成器输出方波时,存在明显的重影现象,这直接影响了方波的质量。对方波重影出现的原因进行了分析,并提出一种适用于FPGA的改进算法,较好地弱化了方波重影。

  15. Influence of the intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd : YAG laser

    NARCIS (Netherlands)

    Yermachenko, VM; Karle, RA; Petrovskiy, VN; Protsenko, ED

    2005-01-01

    The influence of intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd:YAG laser is studied theoretically and experimentally. Various configurations of the optical cavity with II-type phase-matching frequency-doubling crystals are considered. The conditions

  16. Self-induced laser line sweeping and self-pulsing in double-clad fiber lasers in Fabry-Perot and unidirectional ring cavities

    Science.gov (United States)

    Peterka, Pavel; Navrátil, Petr; Dussardier, Bernard; Slavík, Radan; Honzátko, Pavel; Kubecek, Václav

    2012-06-01

    Rare-earth doped fiber lasers are subject to instabilities and various self-pulsed regimes that can lead to catastrophic damage of their components. An interesting self-pulsing regime accompanied with laser wavelength drift with time is the so called self-induced laser line sweeping (SLLS). Despite the early observations of the SLLS in solid-state ruby lasers, in fiber lasers it was first time mentioned in literature only in 2009 where such a laser wavelength drift with time was observed in a relatively broad range of about 1076 -1084 nm in ring ytterbium-doped fiber laser (YDFL). The main characteristic of the SLLS is the scanning of the laser wavelength from shorter to longer wavelength, spanning over large interval of several nanometers, and instantaneous bounce backward. The period of this sweeping is usually quite long, of the order of seconds. This spectacular effect was attributed to spatial-hole burning caused by standing-wave in the laser cavity. In this paper we present experimental investigation of the SLLS in YDFLs in Fabry-Perot cavity and ring cavities. The SLLS was observed also in erbium-doped fiber laser around 1560 nm. We present for the first time observation of the laser wavelength sweep in reverse direction, i.e., from longer towards shorter wavelengths. It was observed in YDFL around 1080 nm.

  17. Deep drawing experiences of niobium disk for PEFP SRF cavity prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Sung; An, Sun; Zhang, Liping; Tang, Yazhe; Li, Ying Min; Kwon, Hyeok Jung; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    A superconducting radio frequency (SRF) cavity with a geometrical beta of 0.42 has been designed to accelerate a proton beam after 100 MeV for an extension of Proton Engineering Frontier Project (PEFP). The designed cavity shape is an elliptical and the resonant frequency is 700 MHz. In order to confirm the RF and mechanical properties of the cavity, two prototypes of copper cavities have been fabricated and tested. Based on the experiences gained with the copper prototypes, two niobium prototypes have been designed. One is two-cell cavity and the other is five cell cavity. The two-cell cavity is for finalizing the niobium cavity production procedure and testing the cavity RF properties at a low temperature and moderate power level. The five-cell cavity is for checking the production quality and testing vertical test system in the future. Both of them are under fabrication. Through the fabrication of the niobium prototype, several issues such as deep drawing, electron beam welding and surface treatment will be addressed. The drawing of the PEPF SRF low beta cavity is shown in Fig. 1. Major parameters for the cavity are like following. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 per cavity - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m - Field flatness: 1.56 % - Cell to cell coupling: 1.41 % - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Lorentz force detuning: 0.4 Hz/(MV/m)2 - Stiffening structure: Double ring - Effective length: 0.45 m - External Q of FPC: 8.0E5 {+-}20 % - HOM load: less than 2 W - HOM Qext requirement: less than 3.0E5 At present, all the niobium disk and plates for cavity and NbTi flanges for beam pipe flange are prepared.

  18. Comparison of Multi-field Coupling Analysis of Accelerator Cavity

    Institute of Scientific and Technical Information of China (English)

    LI; Chun-guang; LI; Jin-hai

    2013-01-01

    In the high power accelerator cavity,the joule heat produced by the electromagnetic fields causes the temperature of the cavity rising which leads to frequency changed,called frequency shift.The analysis of the effect of power to the frequency shift is an important task of accelerator cavity design.It involves heat,structure and high frequency analysis.

  19. Comment on: Investigation of the thermal lens effect of the TGG crystal in high-power frequency-doubled laser with single frequency operation

    CERN Document Server

    Eismann, Ulrich

    2015-01-01

    In their article, the authors of [Opt. Express 23, 4981 (2015)] observe step-like behavior and hysteresis of the output power of a diode-end-pumped Nd:YVO 4-laser as a function of pump power. While claiming that this behavior is a proof of thermal lensing in the intra-cavity TGG, no direct evidence is given. We will discuss here the validity of their statement, and propose an experimental proof.

  20. Intermittency and chaos in intracavity doubled lasers. II

    Energy Technology Data Exchange (ETDEWEB)

    James, G.E.; Harrell, E.M. II (School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia 30332 (USA)); Roy, R. (School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (USA))

    1990-03-01

    We describe the nonlinear dynamics of intracavity doubled multimode lasers. Baer (J. Opt. Soc. Am. B 3, 1175 (1986)) observed irregular amplitude fluctuations in a multimode yttrium aluminum garnet laser with an intracavity potassium titanyl phosphate frequency-doubling crystal; we identify type-III intermittency as the route to chaos. Subsequently, Oka and Kubota (Opt. Lett. 13, 805 (1988)) demonstrated the stabilization of such a laser by the introduction of a quarter wave plate into the cavity. A generalized model of rate equations for this case is introduced. It is shown that a second route to chaos through a Hopf bifurcation, synchronization, and period-doubling sequence occurs on rotation of the quarter wave plate within the cavity. In addition, we predict that the laser output may be stable for particular lengths of the doubling crystal.

  1. Niobium superconducting cavity

    CERN Multimedia

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  2. Simultaneous Q-switching and Frequency-doubling by a Single KTP Crystal in a Diode-pumped Nd: YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; HUO Yujing; HE Shufang; FENG Lichun

    2000-01-01

    The interrelation between the phase matching condition for second harmonic generation (SHG) and the electro-optic Q-switching in KTP was numerically analyzed. A diode-pumped Q-switched Nd: YVO4/KTP green laser was reported, where the KTP crystal was simultaneously used as both an electrooptic Q-switcher and a frequency-doubling crystal in type Ⅱ phase matching.Compared with the conventional frequency-doubling and Q-switching configuration, low loss and high efficiency characteristics were realized by using a single KTP crystal. The Q-switched green laser pulse with a peak power of 762 W and a pulse width of 12 ns was obtained with 1 W pump power.

  3. Evaluation of Optical Properties of Self-Frequency-Doubling Crystal Yb:GdYAl3(BO3)4 for Laser Applications

    Institute of Scientific and Technical Information of China (English)

    LI Jing; LI Qiang; WANG Ji-Yang; ZHAO Hong-Yang

    2007-01-01

    @@ Yb:GdYAl3(BO3)4(Yb:GdYAB) is investigated as a new laser crystal for potential applications in self-frequency doubling. The emission and absorption properties of Yb:GdYAB crystal are studied, and the emission decay times of the upper laser level are measured. The emission cross sections are evaluated using the absorption cross section and principle of reciprocity. The other laser performance parameters, such as the minimum inversion fraction βmin, pump saturation intensity Isat and minimum pump intensity Imin, are also calculated. The results are discussed in the framework of requirements for an effective diode-pumped Yb3+ laser system. Yb:GdYAB is expected to exhibit the most useful laser properties and to be superior to Yb:YAB crystal that has been excellent self-frequency-doubling crystal at present in many key spectroscopic parameter values.

  4. Laser radiation frequency doubling in a single-crystal fibre based on a stoichiometric LiNbO{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kashin, V V; Nikolaev, D A; Rusanov, S Ya; Tsvetkov, V B [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-01-31

    We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (λ = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO{sub 2} laser (LHPG-method). (nonlinear optical phenomena)

  5. Determination of Light-beam Dispersion Angle by BBO Frequency-doubling%BBO倍频法测定光束发散角

    Institute of Scientific and Technical Information of China (English)

    沙先武; 是度芳; 陈长水; 谢建平

    2000-01-01

    A new method is designed to determinate the light beam dispersion angle according to the fact that the BBO crystal has a certain phase match angle on certain light-frequencies while doubling frequency. The method is simple and more precise.%光束发散角的测定方法有多种,本文提出一种新的测定方法,利用BBO晶体倍频中的角度匹配来测定发散角,精度较高.

  6. High-power 660.5 nm red laser from diode-side-pumped intracavity frequency-doubled Nd:YLF laser

    Science.gov (United States)

    Wang, Zhichao; Wang, Baoshan; Chen, Ming; Yang, Feng; Zhang, Shenjin; Zhang, Xiaowen; Bo, Yong; Xu, Yiting; Zong, Nan; Xu, Jialin; Peng, Qinjun; Cui, Dafu; Xu, Zuyan

    2015-12-01

    We demonstrate a high-power red laser at 660.5 nm from intracavity frequency doubling of a diode-side-pumped 1321 nm Nd:LiYF4 (Nd:YLF) ring laser in a LiB3O5 (LBO) crystal. The maximum average output power of the red laser is obtained to be 23 W with beam quality factor M 2  =  1.3.

  7. Power-stabilization of high frequency gyrotrons using a double PID feedback control for applications to many high power THz spectroscopy

    OpenAIRE

    Kuleshov, Alexei; Ueda, Keisuke; Idehara, Toshitaka

    2013-01-01

    High stabilization of the output power of high frequency gyrotrons for high power THzspectroscopy is an important issue in order to extend the applications of gyrotrons to wider subjects.For this objective, we tried a PID feedback control on a heater current of a triode magnetroninjection gun (MIG) for stabilization of an electron beam current and an additional PID control ofan anode voltage of the gun for direct stabilization of output power. This double PID controlachieves effective respons...

  8. Process and application of shock compression by nanosecond pulses of frequency-doubled Nd:YAG laser

    Science.gov (United States)

    Sano, Yuji; Kimura, Motohiko; Mukai, Naruhiko; Yoda, Masaki; Obata, Minoru; Ogisu, Tatsuki

    2000-02-01

    The authors have developed a new process of laser-induced shock compression to introduce a residual compressive stress on material surface, which is effective for prevention of stress corrosion cracking (SCC) and enhancement of fatigue strength of metal materials. The process developed is unique and beneficial. It requires no pre-conditioning for the surface, whereas the conventional process requires that the so-called sacrificial layer is made to protect the surface from damage. The new process can be freely applied to water- immersed components, since it uses water-penetrable green light of a frequency-doubled Nd:YAG laser. The process developed has the potential to open up new high-power laser applications in manufacturing and maintenance technologies. The laser-induced shock compression process (LSP) can be used to improve a residual stress field from tensile to compressive. In order to understand the physics and optimize the process, the propagation of a shock wave generated by the impulse of laser irradiation and the dynamic response of the material were analyzed by time-dependent elasto-plastic calculations with a finite element program using laser-induced plasma pressure as an external load. The analysis shows that a permanent strain and a residual compressive stress remain after the passage of the shock wave with amplitude exceeding the yield strength of the material. A practical system materializing the LSP was designed, manufactured, and tested to confirm the applicability to core components of light water reactors (LWRs). The system accesses the target component and remotely irradiates laser pulses to the heat affected zone (HAZ) along weld lines. Various functional tests were conducted using a full-scale mockup facility, in which remote maintenance work in a reactor vessel could be simulated. The results showed that the system remotely accessed the target weld lines and successfully introduced a residual compressive stress. After sufficient training

  9. Efficacy and Safety of a Lidocaine Gel in Patients from 6 Months up to 8 Years with Acute Painful Sites in the Oral Cavity: A Randomized, Placebo-Controlled, Double-Blind, Comparative Study

    Directory of Open Access Journals (Sweden)

    Dörte Wolf

    2015-01-01

    Full Text Available Lidocaine is a well-accepted topical anaesthetic, also used in minors to treat painful conditions on mucosal membranes. This randomized, double-blind, placebo-controlled study (registered prospectively as EudraCT number 2011-005336-25 was designed to generate efficacy and safety data for a lidocaine gel (2% in younger children with painful conditions in the oral cavity. One hundred sixty-one children were included in two subgroups: 4–8 years, average age 6.4 years, treated with verum or placebo and 6 months–<4 years, average age 1.8 years, treated only with verum. Pain reduction was measured from the time prior to administration to 10 or 30 minutes after. In addition, adverse events and local tolerability were evaluated. In group I, pain was reduced significantly after treatment with verum compared to placebo at both time points. In group II, the individual pain rating shift showed statistically significant lower pain after treatment. Only seven out of 161 patients reported an adverse event but none were classified as being related to the study medication. The local tolerability was assessed as very good in over 97% of cases. For painful sites in the oral cavity, a 2% lidocaine gel is a meaningful tool for short-term treatment in the paediatric population.

  10. Design and RF test of MEBT buncher cavities for C-ADS Injector II at IMP

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shichun; Jia, Huan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Niu, Haihua [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); He, Yuan, E-mail: hey@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang, Shenghu; Yuan, Chenzhang [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Jing [Lanzhou University of Technology, Lanzhou 730050 (China); Zhang, Shengxue; Chang, Wei; Zhang, Peng; Zhao, Hongwei; Xia, Jiawen [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-11-01

    Abstracts: To match the beam from the Radio Frequency Quadrupole (RFQ) accelerator to the Superconducting Half-wave Resonator (HWR) Linac, two room temperature (RT) double-gap Quarter-wave Resonator (QWR) bunchers are designed to be located in the Medium Energy Beam Transport Line (MEBT) for the C-ADS Injector II at IMP. Both cavities work at 162.5 MHz, with β=0.067 and a beam aperture diameter of 40 mm. The effective voltage of these two cavities needs to reach 135 kV in Continuous Wave (CW) mode. In this paper, the RF design and thermal analysis of the cavities will be presented, along with the tuners and coupler consideration. The measured frequencies, R{sub sh}/Q{sub 0}, Q{sub 0} and voltage of the cavities agree well with the simulation result. Details of the RF test results including the full power tests of the cavities will be shown. - Highlights: • High bunching voltage for this type of cavity with limited longitudinal length in MEBT line. • Using copper-plated stainless technique for cavity outer conductor. • Spiral cooling channel design for stem cooling.

  11. Cavity magnomechanics.

    Science.gov (United States)

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

    2016-03-01

    A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and its application as a new information transduction platform based on coherent coupling between photons, phonons, and magnons. PMID:27034983

  12. Dental cavities

    Science.gov (United States)

    ... leading to cavities. Treatment may involve: Fillings Crowns Root canals Dentists fill teeth by removing the decayed tooth ... gold, porcelain, or porcelain attached to metal. A root canal is recommended if the nerve in a tooth ...

  13. Effect of asymmetrical double-pockets and gate-drain underlap on Schottky barrier tunneling FET: Ambipolar conduction vs. high frequency performance

    Science.gov (United States)

    Shaker, Ahmed; Ossaimee, Mahmoud; Zekry, A.

    2016-08-01

    In this paper, a proposed structure based on asymmetrical double pockets SB-TFET with gate-drain underlap is presented. 2D extensive modeling and simulation, using Silvaco TCAD, were carried out to study the effect of both underlap length and pockets' doping on the transistor performance. It was found that the underlap from the drain side suppresses the ambipolar conduction and doesn't enhance the high-frequency characteristics. The enhancement of the high-frequency characteristics could be realized by increasing the doping of the drain pocket over the doping of the source pocket. An optimum choice was found which gives the conditions of minimum ambipolar conduction, maximum ON current and maximum cut-off frequency. These enhancements render the device more competitive as a nanometer transistor.

  14. Quasi-continuous-wave 589-nm radiation based on intracavity frequency-doubled Nd:GGG/BaWO4 Raman laser

    Science.gov (United States)

    Liu, Yang; Liu, Zhaojun; Cong, Zhenhua; Men, Shaojie; Rao, Han; Xia, Jinbao; Zhang, Sasa; Zhang, Huaijin

    2016-07-01

    Quasi-continuous-wave (QCW) 589-nm radiation was realized based on a frequency-doubled crystalline Raman laser. The fundamental wave with macro-micro-pulse trains was generated from an acousto-optically Q-switched QCW diode side-pumped Nd:GGG laser. Intracavity Raman conversion was accomplished by a BaWO4 crystal and the second harmonic generation was finished by a KTP crystal. Under a pumping power of 126.0 W with a macro-pulse frequency of 300 Hz and duration of 300 μs, the maximum 589 nm output power of 4.2 W was obtained at a micro-pulse frequency of 33.3 kHz. The micro-pulse width was 13.6 ns.

  15. Comparison of performance between bipolar and unipolar double-frequency sinusoidal pulse width modulation in a digitally controlled H-bridge inverter system

    Institute of Scientific and Technical Information of China (English)

    Lei Bo; Xiao Guo-Chun; Wu Xuan-Lü

    2013-01-01

    By deriving the discrete-time models of a digitally controlled H-bridge inverter system modulated by bipolar sinusoidal pulse width modulation (BSPWM) and unipolar double-frequency sinusoidal pulse width modulation (UDFSPWM)respectively,the performances of the two modulation strategies are analyzed in detail.The circuit parameters,used in this paper,are fixed.When the systems,modulated by BSPWM and UDFSPWM,have the same switching frequency,the stability boundaries of the two systems are the same.However,when the equivalent switching frequencies of the two systems are the same,the BSPWM modulated system is more stable than the UDFSPWM modulated system.In addition,a convenient method of establishing the discrete-time model of piecewise smooth system is presented.Finally,the analytical results are confirmed by circuit simulations and experimental measurements.

  16. Highly stable piezoelectrically tunable optical cavities

    CERN Document Server

    Möhle, Katharina; Döringshoff, Klaus; Nagel, Moritz; Peters, Achim

    2013-01-01

    We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

  17. Theory and technology for superconducting cavities

    CERN Document Server

    Lengeler, Herbert

    1993-01-01

    The course will address Physicist and Engineers who are newcomers in the field of accelerators and accelerating cavities. The elements of RF-Superconductivity will be presented with special relevance to accelerating cavities. The present ststus of achievable accelerating fields and RF losses will be given and their link to the special technologies for cavity fabrication and surface treatments will be stressed. Cavity auxiliaries like main couplers, higher order mode couplers and frequency tuners will be described.

  18. 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.

  19. accelerating cavity

    CERN Multimedia

    On the inside of the cavitytThere 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.

  20. 2.1-watts intracavity-frequency-doubled all-solid-state light source at 671 nm for laser cooling of lithium

    CERN Document Server

    Eismann, Ulrich; Salomon, Christophe; Chevy, Frédéric

    2013-01-01

    We present an all-solid-state laser source emitting up to 2.1 W of single-frequency light at 671 nm developed for laser cooling of lithium atoms. It is based on a diode-pumped, neodymium-doped orthovanadate (Nd:YVO$_4$) ring laser operating at 1342 nm. Optimization of the thermal management in the gain medium results in a maximum multi-frequency output power of 2.5 W at the fundamental wavelength. We develop a simple theory for the efficient implementation of intracavity second harmonic generation, and its application to our system allows us to obtain nonlinear conversion efficiencies of up to 88%. Single-mode operation and tuning is established by adding an etalon to the resonator. The second-harmonic wavelength can be tuned over 0.5 nm, and mode-hop-free scanning over more than 6 GHz is demonstrated, corresponding to around ten times the laser cavity free spectral range. The output frequency can be locked with respect to the lithium $D$-line transitions for atomic physics applications. Furthermore, we obser...

  1. Spallation neutron source RF cavity bias system

    International Nuclear Information System (INIS)

    The Spallation Neutron Source r.f. cavity bias system is described under the topic headings: bias system, r.f. cavity, cables, d.c. bias power supply, transistor regulator and control system. Calculation of 4 core 300 mm solid aluminium cable inductance, coaxial shunt frequency response and transistor regulator computed frequency response, are discussed in appendices 1-3. (U.K.)

  2. THE SIX-WHEEL FRIGHT TRUCK LOCOMOTIVE OF DOUBLE DELIVERY USES RADIO-FREQUENCY TRANSFER WITH PADDING AND ASYNCHRONIZED TRACTION IMPELLENTS

    Directory of Open Access Journals (Sweden)

    M. H. Visin

    2010-10-01

    Full Text Available Our research offers a new perspective loading pattern of the 12-wheel double-feed freight electric locomotive with the asynchronous tractive motor using an adapter transformer with the high-frequency uncoupler. This will make it possible to decrease the traction-feeding transformer mass 2.3 times, to remove the current pulse advancing on the track circuit and therefore the influence on the work of the ALSE and CBS. So the railway traffic safety will be increased considerably.

  3. Experiment Study of Dual Wavelength and Dual Pulse Q-switched Intracavity Frequency Doubling of a Tunable Cr:LiSAF Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Changshui; WANG Peilin; XIE Jianping; SHI Dufang; SHA Xianwu; HE Yulong

    2001-01-01

    In this paper, a flashlamp-pumped Q-switched Cr: LiSAF laser system with intracavity frequency doubling is designed to obtain dual pulse and dual wavelength laser output. The behaviors of second harmonic output of dual pulse and dual wavelength are studied experimentally. Good results are obtained in experiments: the output energy of each second harmonic pulse a round 448.1 nm is 10.2 mJ, the dual pulse time interval can be tuned widely, and the tunable range of each second harmonic wavelength is 448.1 to 465 nm.

  4. Near-diffraction-limited green source by frequency doubling of a diode-stack pumped Q-switched Nd:YAG slab oscillator-amplifier system.

    Science.gov (United States)

    Zhang, Hengli; Liu, Xiaomeng; Li, Daijun; Shi, Peng; Schell, Alex; Haas, Claus Rüdige; Du, Keming

    2007-09-10

    A near-diffraction-limited, stable, 18 mJ green source with a pulse width of 16.7 ns was generated at a 1 kHz repetition rate by frequency doubling of diode stacks end-pumped electro-optically Q-switched slab Nd:YAG oscillator-amplifier system. The pump to green optical conversion efficiency was 10.7%. At the output energy of 15 mJ at 532 nm, the M2 factors were 1.3 and 1.7 in the unstable and stable directions, respectively. The energy pulse stability was approximately 0.8%.

  5. 软X射线双频光栅剪切干涉法研究%Studies on soft X-ray shearing interferometry with double-frequency gratings∗

    Institute of Scientific and Technical Information of China (English)

    刘正坤; 邱克强; 陈火耀; 刘颖; 徐向东; 付绍军; 王琛; 安红海; 方智恒

    2013-01-01

    The M-Z interferometer with gratings or multilayer mirrors is widely used in the X-ray laser plasma diagnoses; however, this system is difficult to adjust, and results in the low success rate in experiment. Since wavefront shearing interferometers do not need a separate reference wavefront, they have inherent advantages compared with conventional interferometers. But the absence of shearing element for soft X-ray has restrained the application of the shearing interferometry in soft X-ray measurement. In this paper, a new-structured double-frequency grating was proposed and fabricated that served as the shearing element for soft X-rays, which can promote the application of shearing interferometers in the X-ray laser plasma diagnoses. The diffraction characteristics of the double-frequency grating are analyzed and tested in the synchrotron radiation beams. It is found that the intensity ratio of the two working diffracted beams is over 75%, and the intensity ratio of the rest diffracted beam to the working beam is less than 5%. An X-ray shearing interferometer using a double-frequency grating with 1000 lines/mm and 1002.5 lines/mm gratings was set up, and a clear shear interferogram was obtained. The experimental results demonstrated that the soft X-ray shearing interferometer using double-frequency grating can be applied in the X-ray laser plasma diagnoses.%  本文中设计了一种利用软X射线双频光栅作为剪切干涉元件的剪切系统,使剪切干涉法在软X射线波段得到了应用。介绍了软X射线双频光栅的结构及衍射特性,在同步辐射光束线对双频光栅的效率分布进行了测试实验,两个剪切级次的效率比值高于75%,干扰级次效率低于5%。利用软X射线双频光栅为剪切干涉光学元件,对待测靶进行了静态检测,得到了对比度高,稳定的干涉条纹,验证了该方法在软X射线等离子体密度诊断中的可行性。

  6. All-solid-state 704 mW continuous-wave yellow source based on an intracavity, frequency-doubled crystalline Raman laser.

    Science.gov (United States)

    Dekker, Peter; Pask, Helen M; Piper, James A

    2007-05-01

    Continuous-wave operation at 588 nm of a diode-pumped Nd:GdVO4 laser with intracavity Raman shifting [in KGd(WO4)2, KGW] and frequency-doubling (in LiB3O5, LBO) is reported. A maximum cw power at 588 nm of 704 mW was obtained for diode pump powers of 13.7 W. Quasi-cw yellow powers up to 1.57 W at a 50% duty cycle (to reduce thermal load in the laser crystal) indicate that power scaling to over 1 W is feasible. PMID:17410253

  7. Continuous-wave violet generation at 373.5 nm by frequency-doubled power-scaled near-infrared emitting Pr:YAlO3 laser

    Science.gov (United States)

    Fibrich, Martin; Jelínková, Helena

    2013-10-01

    We report on a continuous-wave Pr:YAlO3 laser operating at a wavelength of 373.5 nm in a power-scaled resonator arrangement. Violet light generation has been achieved by intracavity frequency doubling of the near-infrared emitting Pr:YAP laser at a fundamental wavelength of 747 nm. For active medium pumping, two GaN laser diodes providing up to 1 W of output power each at 448 nm were used. By employing BBO crystal as a nonlinear medium, more than 46 mW of violet radiation has been obtained.

  8. Mechanical Properties of Niobium Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Dhakal, Pashupati [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Matalevich, Joseph R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Myneni, Ganapati Rao [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.

  9. Niobium LEP 2 accelerating cavities

    CERN Multimedia

    An accelerating cavity from LEP. This could be cut open to show the 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 were used in an upgrade of the LEP accelerator to double the energy of the particle beams.

  10. Comparative study on the intracavity frequency-doubling 532 nm laser based on gray-tracking-resistant KTP and conventional KTP.

    Science.gov (United States)

    Huang, H-T; Qiu, G; Zhang, B-T; He, J-L; Yang, J-F; Xu, J-L

    2009-11-10

    A comparative study of a frequency-doubling 532 nm laser based on gray-tracking-resistant KTP (GTR-KTP) and conventional KTP is presented. The intracavity GTR-KTP was proved to have better temperature characteristics than that of conventional KTP. Within the normalized output power variation range of 0.8-1.0, GTR-KTP has a temperature tolerance of 35 degrees C, broader than the 21 degrees C obtained with conventional KTP. Under the laser diode (LD) pump power of 180 W, the maximum average output power at 532 nm was 40.6 W for GTR-KTP at a repetition frequency of 10 kHz. In the case of conventional KTP, the maximum available LD pump power was limited to 150 W, with the corresponding maximum green average output power of 27.2 W. PMID:19904338

  11. Optomechanical Cavity with a Buckled Mirror

    CERN Document Server

    Yuvaraj, D; Shtempluck, Oleg; Buks, Eyal

    2012-01-01

    We study an optomechanical cavity, in which a buckled suspended beam serves as a mirror. The mechanical resonance frequency of the beam obtains a minimum value near the buckling temperature. Contrary to the common case, in which self-excited oscillations of the suspended mirror are optically induced by injecting blue detuned laser light, in our case self-excited oscillations are observed with red detuned light. These observations are attributed to a retarded thermal (i.e. bolometric) force acting on the buckled mirror in the inwards direction (i.e. towards to other mirror). With relatively high laser power other interesting effects are observed including period doubling of self-excited oscillations and intermode coupling.

  12. Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial.

    Science.gov (United States)

    Eskesen, Dorte; Jespersen, Lillian; Michelsen, Birgit; Whorwell, Peter J; Müller-Lissner, Stefan; Morberg, Cathrine M

    2015-11-28

    The aim of the present study was to investigate the effect of Bifidobacterium animalis subsp. lactis, BB-12®, on two primary end points - defecation frequency and gastrointestinal (GI) well-being - in healthy adults with low defecation frequency and abdominal discomfort. A total of 1248 subjects were included in a randomised, double-blind, placebo-controlled trial. After a 2-week run-in period, subjects were randomised to 1 or 10 billion colony-forming units/d of the probiotic strain BB-12® or a matching placebo capsule once daily for 4 weeks. Subjects completed a diary on bowel habits, relief of abdominal discomfort and symptoms. GI well-being, defined as global relief of abdominal discomfort, did not show significant differences. The OR for having a defecation frequency above baseline for ≥50% of the time was 1·31 (95% CI 0·98, 1·75), P=0·071, for probiotic treatment overall. Tightening the criteria for being a responder to an increase of ≥1 d/week for ≥50 % of the time resulted in an OR of 1·55 (95% CI 1·22, 1·96), P=0·0003, for treatment overall. A treatment effect on average defecation frequency was found (P=0·0065), with the frequency being significantly higher compared with placebo at all weeks for probiotic treatment overall (all P<0·05). Effects on defecation frequency were similar for the two doses tested, suggesting that a ceiling effect was reached with the one billion dose. Overall, 4 weeks' supplementation with the probiotic strain BB-12® resulted in a clinically relevant benefit on defecation frequency. The results suggest that consumption of BB-12® improves the GI health of individuals whose symptoms are not sufficiently severe to consult a doctor (ISRCTN18128385). PMID:26382580

  13. Status of the ILC Crab Cavity Development

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Dexter, A.; /Cockcroft Inst. Accel. Sci. Tech.; Beard, C.; Goudket, P.; McIntosh, P.; /Daresbury; Bellantoni, L.; /Fermilab; Grimm, T.; Li, Z.; Xiao, L.; /SLAC

    2011-10-20

    The International Linear Collider (ILC) will require two dipole cavities to 'crab' the electron and positron bunches prior to their collision. It is proposed to use two 9 cell SCRF dipole cavities operating at a frequency of 3.9 GHz, with a transverse gradient of 3.8MV/m in order to provide the required transverse kick. Extensive numerical modelling of this cavity and its couplers has been performed. Aluminium prototypes have been manufactured and tested to measure the RF properties of the cavity and couplers. In addition single cell niobium prototypes have been manufactured and tested in a vertical cryostat. The International Collider (ILC) [1] collides bunches of electrons and positrons at a crossing angle of 14 mrad. The angle between these bunches causes a loss in luminosity due to geometric effects [2]. The luminosity lost from this geometric effect can be recovered by rotating the bunches into alignment prior to collision. One possible method of rotating the bunches is to use a crab cavity [3]. A crab cavity is a transverse defecting cavity, where the phase of the cavity is such that the head and tail of the bunch receive equal and opposite kicks. As the bunches are only 500 nm wide in the horizontal plane, the cavity phase must be strictly controlled to avoid the bunch centre being deflected too much. In order to keep the phase stability within the required limits it is required that the cavity be superconducting to avoid thermal effects in both the cavity and its RF source. At the location of the crab cavity in the ILC there is only 23 cm separation between the centre of the cavity and the extraction line, hence the cavity must be small enough to fit in this space. This, along with the difficulty of making high frequency SRF components, set the frequency of the cavity to 3.9 GHz.

  14. Robust DTC Based on Adaptive Fuzzy Control of Double Star Synchronous Machine Drive with Fixed Switching Frequency

    Science.gov (United States)

    Boudana, Djamel; Nezli, Lazhari; Tlemçani, Abdelhalim; Mahmoudi, Mohand Oulhadj; Tadjine, Mohamed

    2012-05-01

    The double star synchronous machine (DSSM) is widely used for high power traction drives. It possesses several advantages over the conventional three phase machine. To reduce the torque ripple the DSSM are supplied with source voltage inverter (VSI). The model of the system DSSM-VSI is high order, multivariable and nonlinear. Further, big harmonic currents are generated. The aim of this paper is to develop a new direct torque adaptive fuzzy logic control in order to control DSSM and minimize the harmonics currents. Simulations results are given to show the effectiveness of our approach.

  15. High-power Microwave Pulse Compression of Klystrons by Phase-Modulation of High-Q Storage Cavities

    CERN Document Server

    Bossart, Rudolf; Mourier, J; Syratchev, I V; Tanner, L

    2004-01-01

    At the CERN linear electron accelerators LIL and CTF, the peak RF power from the 3GHz-klystrons was doubled by means of LIPS microwave pulse compressors. To produce constant RF power from the cavity-based pulse compressors, the klystrons were driven by a fast RF-phase modulation program. For the CLIC Test Facility CTF3, a new type of a Barrel Open Cavity (BOC) with a high quality factor Q0 has been developed. Contrary to LIPS with two resonant cavities, BOC operates with a single cavity supporting two orthogonal resonant modes TM 10,1,1 in the same cavity. For both LIPS and BOC storage cavities, it is important that the RF power reflected back to the klystron is minimal. This implies that the resonant frequencies, Q-factors and coupling factors of the two resonant modes of a pulse compressor are closely matched, and that the resonant frequencies are accurate to within a few KHz. The effects of small differences between the two orthogonal modes of the BOC cavity have been investigated. The dynamic pulse respon...

  16. CONTROL OF LASER RADIATION PARAMETERS: Characteristics of single-frequency emission from a laser with a cavity based on a Sagnac interferometer

    Science.gov (United States)

    Grabovskii, V. V.; Prokhorenko, V. I.; Yatskiv, D. Ya

    1995-04-01

    An experimental investigation was made of the attainment of highly reproducible single-frequency emission from a pulsed laser based on a Sagnac interferometer. The probability of single-frequency emission was found to be related to the position of a passive switch relative to the optical centre of the interferometer. A qualitative theoretical analysis showed that the observed effect can be due to the scattering of waves on a grating induced in the switch. Experiments indicated that the probability of single-frequency emission was 99.99%.

  17. Generation of Cluster States in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan-Li; YANG Li-Jia; DAI Hong-Yi

    2007-01-01

    We propose two schemes for the generation of cluster states in the context of cavity quantum electrodynamics (QED).In the first scheme,we prepare multi-cavity cluster states with information encoded in the coherent states.The second scheme is to generate multi-atom cluster states,where qubits are represented by the states of cascade Rydberg atoms.Both the schemes are based on the atom-cavity interaction and the atomic spontaneous radiation can be effciently reduced since the cavity frequency is largely detuned from the atomic transition frequency.

  18. Effects of pyridoxine supplementation on severity, frequency and duration of migraine attacks in migraine patients with aura: A double-blind randomized clinical trial study in Iran.

    Directory of Open Access Journals (Sweden)

    Omid Sadeghi

    2015-06-01

    Full Text Available Migraine is a chronic disease that affects nearly 6% of men and 18% of women worldwide. There are various drugs, which can successfully decrease migraine symptoms and frequency of migraine attacks, but these drugs usually are expensive. Hence, this study aimed to assess the effects of pyridoxine supplementation on severity, frequency and duration of migraine attacks as well as headache diary results (HDR.This double-blind randomized clinical trial study was conducted on 66 patients with migraine with aura (MA in Khorshid and Emam Mosa Sadr clinics of Isfahan University of Medical Sciences, Iran, in 2013. Patients were randomly allocated to receive either pyridoxine supplements (80 mg pyridoxine per day or placebo. Severity, frequency and duration of migraine attacks and HDR were measured at baseline and at the end of the study.Mean age of patients was 34.24 ± 9.44 years old. Pyridoxine supplementation led to a significant decrease in headache severity (-2.20 ± 1.70 compared with -1 ± 1.50; P = 0.007, attacks duration (-8.30 ± 12.60 compared with -1.70 ± 9.60; P = 0.030 and HDR (-89.70 ± 134.60 compared with -6.10 ± 155.50; P = 0.040 compared with placebo, but was not effective on the frequency of migraine attacks (-2.30 ± 4 compared with -1.20 ± 7.80; P = 0.510.Pyridoxine supplementation in patients with MA was effective on headache severity, attacks duration and HDR, but did not affect the frequency of migraine attacks.

  19. Effects of pyridoxine supplementation on severity, frequency and duration of migraine attacks in migraine patients with aura: A double-blind randomized clinical trial study in Iran

    Science.gov (United States)

    Sadeghi, Omid; Nasiri, Morteza; Maghsoudi, Zahra; Pahlavani, Naseh; Rezaie, Masoud; Askari, Gholamreza

    2015-01-01

    Background: Migraine is a chronic disease that affects nearly 6% of men and 18% of women worldwide. There are various drugs, which can successfully decrease migraine symptoms and frequency of migraine attacks, but these drugs usually are expensive. Hence, this study aimed to assess the effects of pyridoxine supplementation on severity, frequency and duration of migraine attacks as well as headache diary results (HDR). Methods: This double-blind randomized clinical trial study was conducted on 66 patients with migraine with aura (MA) in Khorshid and Emam Mosa Sadr clinics of Isfahan University of Medical Sciences, Iran, in 2013. Patients were randomly allocated to receive either pyridoxine supplements (80 mg pyridoxine per day) or placebo. Severity, frequency and duration of migraine attacks and HDR were measured at baseline and at the end of the study. Results: Mean age of patients was 34.24 ± 9.44 years old. Pyridoxine supplementation led to a significant decrease in headache severity (−2.20 ± 1.70 compared with −1 ± 1.50; P = 0.007), attacks duration (−8.30 ± 12.60 compared with −1.70 ± 9.60; P = 0.030) and HDR (−89.70 ± 134.60 compared with −6.10 ± 155.50; P = 0.040) compared with placebo, but was not effective on the frequency of migraine attacks (−2.30 ± 4 compared with −1.20 ± 7.80; P = 0.510). Conclusion: Pyridoxine supplementation in patients with MA was effective on headache severity, attacks duration and HDR, but did not affect the frequency of migraine attacks. PMID:26056551

  20. Highly sensitive liquid-level sensor based on dual-wavelength double-ring fiber laser assisted by beat frequency interrogation.

    Science.gov (United States)

    Dai, Yi; Sun, Qizhen; Tan, Sisi; Wo, Jianghai; Zhang, Jiejun; Liu, Deming

    2012-12-01

    A highly sensitive liquid-level sensor based on dual-wavelength single-longitudinal-mode fiber laser is proposed and demonstrated. The laser is formed by exploiting two parallel arranged phase-shift fiber Bragg gratings (ps-FBGs), acting as ultra-narrow bandwidth filters, into a double-ring resonators. By beating the dual-wavelength lasing output, a stable microwave signal with frequency stability better than 5 MHz is obtained. The generated beat frequency varies with the change of dual-wavelength spacing. Based on this characteristic, with one ps-FBG serving as the sensing element and the other one acting as the reference element, a highly sensitive liquid level sensor is realized by monitoring the beat frequency shift of the laser. The sensor head is directly bonded to a float which can transfer buoyancy into axial strain on the fiber without introducing other elastic elements. The experimental results show that an ultra-high liquid-level sensitivity of 2.12 × 10(7) MHz/m within the measurement range of 1.5 mm is achieved. The sensor presents multiple merits including ultra-high sensitivity, thermal insensitive, good reliability and stability.

  1. Methods for precisely controlling the residual stress and temperature coefficient of the frequency of a MEMS resonator based on an AlN cavity silicon-on-insulator platform

    Science.gov (United States)

    Wang, Nan; Xu, Jinghui; Zhang, Xiaolin; Wu, Guoqiang; Zhu, Yao; Li, Wei; Gu, Yuandong

    2016-07-01

    In this paper, we report an experimentally verified numerical model developed for precisely predicting and controlling the initial bending of a multi-layer-stack composite cantilever structure which is caused by the residual stress of the individual constituting layers, as well as the cantilever’s thermal coefficient of frequency (TCF). The developed model is exemplified using a flexural-mode cantilever resonator according to the process flow of the aluminium nitride (AlN) cavity silicon-on-insulator (SOI) platform. The same AlN cavity SOI platform is also utilized to fabricate the exemplified cantilever, which is then used to experimentally verify the accuracy and consistency of the numerical model. The experimental results show a difference of less than 3.5% is observed in terms of the deflection at the tip of the cantilever as compared with the numerical model, demonstrating the accuracy of the developed numerical model and the feasibility to optimize the cantilever’s initial deflection and TCF simultaneously, achieving minimum values for both parameters at the same time.

  2. Performance evaluation of coherent free space optical communications with a double-stage fast-steering-mirror adaptive optics system depending on the Greenwood frequency.

    Science.gov (United States)

    Liu, Wei; Yao, Kainan; Huang, Danian; Lin, Xudong; Wang, Liang; Lv, Yaowen

    2016-06-13

    The Greenwood frequency (GF) is influential in performance improvement for the coherent free space optical communications (CFSOC) system with a closed-loop adaptive optics (AO) unit. We analyze the impact of tilt and high-order aberrations on the mixing efficiency (ME) and bit-error-rate (BER) under different GF. The root-mean-square value (RMS) of the ME related to the RMS of the tilt aberrations, and the GF is derived to estimate the volatility of the ME. Furthermore, a numerical simulation is applied to verify the theoretical analysis, and an experimental correction system is designed with a double-stage fast-steering-mirror and a 97-element continuous surface deformable mirror. The conclusions of this paper provide a reference for designing the AO system for the CFSOC system. PMID:27410346

  3. Determination of Matrine and Oxymatrine in Radix Sophorae Flavescentis by Resonance Rayleigh Scattering, Second-order Scattering and Frequency Doubling Scattering Technique

    Institute of Scientific and Technical Information of China (English)

    SONG Yan-qi; LIU Shao-pu; LIU Zhong-fang; HU Xiao-li

    2011-01-01

    In 0.1 mol/L HCl medium,12-tungstophosphoric(TP) acid reacted with matrine(Mat) and oxymatrine(Oxy)to form an ion-association complex.As a result,the new spectra of resonance Rayleigh scattering(RRS),second-order scattering(SOS) and frequency doubling scattering(FDS) appeared and their intensities were enhanced greatly.The maximum scattering wavelengths of RRS,SOS and FDS were located at 370,670 and 390 nm,respectively.The increments of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range.Based on this,the method for the determination of matrine and oxymatrine has been established.It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result.The reaction mechanism and reasons of RRS enhancement were discussed.

  4. All-solid-state continuous-wave frequency-doubled Nd:YAG-BiBO laser with 2.8-W output power at 473 nm.

    Science.gov (United States)

    Czeranowsky, C; Heumann, E; Huber, G

    2003-03-15

    We report on a diode-pumped Nd:YAG laser with 4.6 W of linear polarized continuous-wave (cw) output power on the 4F3/2 --> 4I9/2 transitions at 946 nm. Three different crystals, cut for critical type I phase matching at room temperature, are used for the intracavity frequency doubling of the laser: 10-mm-long LiBaO5 (LBO), an 8-mm-long beta-BaB2O4 (BBO), and a 10.4-mm-long BiB3O6 (BiBO) grown by FEE GmbH. Up to 2.8 W of cw output power in the blue spectral range at 473 nm has been achieved with the BiBO crystal (2.1 W with BBO and 1.5 W with LBO).

  5. 80-W green KTP laser used in photoselective laser vaporization of the prostrate by frequency doubling of Yb 3+ -doped large-mode area fiber laser

    Science.gov (United States)

    Xia, Hongxing; Li, Zhengjia

    2007-05-01

    Photoselective laser vaporization of the prostate (PVP) is the most promising method for the treatment of benign prostatic hyperplasia (BPH), but KTP lasers used in PVP with lamp-pumped are low efficient .To increase the efficiency , we develop a 80-W, 400kHz, linearly polarized green laser based on a frequency-doubled fiber laser. A polarization-maintaining large-mode area (LMA) fiber amplifier generate polarized 1064nm fundamental wave by amplifying the seed signal from a composite Cr 4+:YAG-Nd 3+:YAG crystal fiber laser. The fundamental wave is injected into a KTP crystal with confined temperature management to achieve second harmonic generation (SHG). The overall electrical efficiency to the green portion of the spectrum is 10%.80-W maintenance-free long-lifetime KTP laser obtained can well satisfy the need of PVP.

  6. Measuring solid-state quantum yields: The conversion of a frequency-doubled Nd:YAG diode laser pointer module into a viable light source.

    Science.gov (United States)

    Daglen, Bevin C; Harris, John D; Dax, Clifford D; Tyler, David R

    2007-07-01

    This article outlines the difficulties associated with measuring quantum yields for solid-state samples using a high-pressure mercury arc lamp as the irradiation source. Details are given for the conversion of an inexpensive frequency-doubled neodymium-doped yttrium aluminum garnet (Nd:YAG) diode laser pointer module into a viable irradiation source. The modified Nd:YAG laser was incorporated into a computer-controlled system, which allowed for the simultaneous irradiation and spectroscopic monitoring of the sample. The data obtained with the Nd:YAG diode laser system show far less scatter than data obtained with a high-pressure Hg arc lamp, and consequently the degradation rates obtained with the laser system could be calculated with far greater accuracy. PMID:17672778

  7. High power, picosecond green laser based on a frequency-doubled, all-fiber, narrow-bandwidth, linearly polarized, Yb-doped fiber laser

    Science.gov (United States)

    Tian, Wenyan; Isyanova, Yelena; Stegeman, Robert; Huang, Ye; Chieffo, Logan R.; Moulton, Peter F.

    2016-03-01

    We report on the development of an all-fiber, 68-kW-peak-power, 16-ps-pulse-width, narrow-bandwidth, linearly polarized, 1064-nm fiber laser suitable for high-power, picosecond-pulse-width, green-light generation. Our 1064-nm fiber laser delivered an average power of up to 110 W at a repetition of 100- MHz in a narrow bandwidth, with minimal nonlinear distortion. We developed a high-power, picosecond green source at 532 nm through use of single-pass frequency-doubling of our 1064-nm fiber laser in lithium triborate (LBO). Using a 15-mm long LBO crystal, we have generated 30 W of average power in the second harmonic with 73-W of fundamental average power, for a conversion efficiency of 41%.

  8. 28W red light output at 659.5nm by intracavity frequency doubling of a Nd:YAG laser using LBO.

    Science.gov (United States)

    Peng, Haibo; Hou, Wei; Chen, Yahui; Cui, Dafu; Xu, Zuyan; Chen, Chuantian; Fan, Feidie; Zhu, Yong

    2006-05-01

    High-power, acoustooptic Q-switched red laser output is obtained by intracavity frequency-doubling a Nd:YAG laser operating at wavelength of 1.319 microm with a LiB(3)O(5) (LBO) crystal. 28 W average power at 659.5 nm was demonstrated at 5 kHz and a pulse width of 250+/-10 ns (FWHM). The beam quality of M2 value is 22+/-3 in both horizontal and vertical directions. The conversion efficiency and the stability of the red laser output power at 659.5 nm were both improved through the suppression of 1.338 mum operation by means of a thin YAG etalon. The long-term stability of the red light is better than 1% at an output of 23 W during 200 hours. PMID:19516543

  9. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses.

    Science.gov (United States)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-06-20

    For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.

  10. All-solid-state continuous-wave frequency-doubled Nd:YAG-BiBO laser with 2.8-W output power at 473 nm.

    Science.gov (United States)

    Czeranowsky, C; Heumann, E; Huber, G

    2003-03-15

    We report on a diode-pumped Nd:YAG laser with 4.6 W of linear polarized continuous-wave (cw) output power on the 4F3/2 --> 4I9/2 transitions at 946 nm. Three different crystals, cut for critical type I phase matching at room temperature, are used for the intracavity frequency doubling of the laser: 10-mm-long LiBaO5 (LBO), an 8-mm-long beta-BaB2O4 (BBO), and a 10.4-mm-long BiB3O6 (BiBO) grown by FEE GmbH. Up to 2.8 W of cw output power in the blue spectral range at 473 nm has been achieved with the BiBO crystal (2.1 W with BBO and 1.5 W with LBO). PMID:12659270

  11. 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.

  12. Three-qubit Fredkin gate based on cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Shao Xiao-Qiang; Chen Li; Zhang Shou

    2009-01-01

    This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity.The scheme is based on the dispersive atom-cavity interaction.By modulating the cavity frequency and the atomic transition frequency appropriately,it obtains the effective form of nonlinear interaction between photons in the three-mode cavity.This availability is testified via numerical analysis.It also considers both the situations with and without dissipation.

  13. Geometry-Invariant Resonant Cavities

    CERN Document Server

    Liberal, Iñigo; Engheta, Nader

    2015-01-01

    Resonant cavities are one of the basic building blocks in various disciplines of science and technology, with numerous applications ranging from abstract theoretical modeling to everyday life devices. The eigenfrequencies of conventional cavities are a function of its geometry, and, thus, the size and shape of a resonant cavity is selected in order to operate at a specific frequency. Here, we demonstrate theoretically the existence of geometry-invariant resonant cavities, i.e., resonators whose eigenfrequency is invariant with respect to geometrical deformations. This effect is obtained by exploiting the unusual properties of zero-index metamaterials, which enable decoupling of the time and spatial field variations. This new class of resonators may inspire alternative design concepts, and it might lead to the first generation of deformable resonant devices.

  14. Observation of dressed intra-cavity dark states

    OpenAIRE

    Wang, Yanhua; Zhang, Jiepeng; Zhu, Yifu

    2011-01-01

    Cavity electromagnetically induced transparency in a coherently prepared cavity-atom system is manifested as a narrow transmission peak of a weak probe laser coupled into the cavity mode. We show that with a resonant pump laser coupling the cavity-confined four-level atoms from free space, the narrow transmission peak of the cavity EIT is split into two peaks. The two peaks represent the dressed intra-cavity dark states and have a frequency separation approximately equal to the Rabi frequency...

  15. Comparison of visual field test results obtained through Humphrey matrix frequency doubling technology perimetry versus standard automated perimetry in healthy children

    Directory of Open Access Journals (Sweden)

    Sibel Kocabeyoglu

    2013-01-01

    Full Text Available Aims : The aim of this study was to compare the visual field test results in healthy children obtained via the Humphrey matrix 24-2 threshold program and standard automated perimetry (SAP using the Swedish interactive threshold algorithm (SITA-Standard 24-2 test. Materials and Methods: This prospective study included 55 healthy children without ocular or systemic disorders who underwent both SAP and frequency doubling technology (FDT perimetry visual field testing. Visual field test reliability indices, test duration, global indices (mean deviation [MD], and pattern standard deviation [PSD] were compared between the 2 tests using the Wilcoxon signed-rank test and paired t-test. The performance of the Humphrey field analyzer (HFA 24-2 SITA-standard and frequency-doubling technology Matrix 24-2 tests between genders were compared with Mann-Whitney U-test. Results: Fifty-five healthy children with a mean age of 12.2 ± 1.9 years (range from 8 years to 16 years were included in this prospective study. The test durations of SAP and FDT were similar (5.2 ± 0.5 and 5.1 ± 0.2 min, respectively, P = 0.651. MD and the PSD values obtained via FDT Matrix were significantly higher than those obtained via SAP (P < 0.001, and fixation losses and false negative errors were significantly less with SAP (P < 0.05. A weak positive correlation between the two tests in terms of MD (r = 0.352, P = 0.008 and PSD (r = 0.329, P = 0.014 was observed. Conclusion: Children were able to complete both the visual test algorithms successfully within 6 min. However, SAP testing appears to be associated with less depression of the visual field indices of healthy children. FDT Matrix and SAP should not be used interchangeably in the follow-up of children.

  16. Laser therapy of freckles and lentigines with quasi-continuous, frequency-doubled, ND:YAG (532 nm) laser: a preliminary report

    International Nuclear Information System (INIS)

    Traditional treatment for freckles and lentigines are often ineffective and associative with significant complications. Newly developed lasers produce excellent results with minimal complications. The aim of this ongoing study is to assess the efficacy and safety of quasi-continuous frequency-doubled Nd-YAG (532 nm) laser in the treatment of these lesion. Twenty adult patients (14 with freckles and 6 with lentigines) were enrolled in the study. In phase I, three test sites in each patient were irradiated with fluences of 1.45, 2.90 and 7.25 J/cm/sup 2/, one fluence per site. Three months after single treatment, the fluence yielding the best response was selected for subsequent treatment of remaining lesions in phase II, variable number of treatments were administered at minimum of four weeks interval. Treatment would continue till no additional improvement occurs. Patients completing phase II wee followed up monthly. In phase I maximum improvement (grade 3 and 4 response i.e. > 5005)% in none). In phase II, 15(75%) of 20 patients manifested more than 50% improvement (p< 0.50). The patients were irradiated 2-6 times at 4-12 weeks intervals. Complications included hypopigmentation (25%), atrophy (15%) and hyperpigmentation (10%). All these were mild and resolved within 2-6 months. No recurrence was noted in 5 patients who had completed the phase II during a mean follow up period of 3.6 months. Quasi-continuous, frequency-doubled Nd:YAG (532 nm) laser safety and effectively treats freckles and lentigines. (authors)

  17. 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)).

  18. Radiotherapy effect on frequency of Candida spp. and on virulence of C. albicans isolated from the oral cavity of head and neck cancer patients

    Directory of Open Access Journals (Sweden)

    Daniela Dambroso

    2009-12-01

    Full Text Available The aim of this study was to investigate the diversity and prevalence of yeasts, and the virulence of C. albicans found in the oral cavity during the course of ionizing radiation treatment of patients with head and neck tumor (HNTP. Samples from 21 HNTP and 24 healthy controls were isolated and identified. C. albicans isolated from two patients during radiotherapy were analyzed for virulence factors. Radiotherapy induced a higher level of both yeast colonization (81% vs 33% and non-albicans Candida (NAC colonization (52.4% vs 4.0% in HNTP than the control group. Patients were colonized by 5 different NAC species: C. glabrata, C. tropicalis, C. parapsilosis, C. krusei and C. kefir. On the other hand, C. albicans colonization was similar in patients and controls (6/21, 28.6% vs 7/24, 29.2%, respectively. Also, of the 11 patients assessed before and during radiotherapy, 5 (45.5% were colonized before the start of treatment and another 5 (45.5% during treatment. All of the latter were colonized by NAC species alone. Moreover, we observed a significant and continuous enhancement of C. albicans virulence as the radiotherapy progressed, in the two patients involved in this test. Thus, it is concluded that radiotherapy is an important predisposing factor for the oral candidiasis, including NAC species. Also, it may facilitate the development of more virulent C. albicans strains. Keywords: Candida. Radiotherapy. Virulence factor. Oral candidiasis.

  19. 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.

  20. Tunable Cavity Optomechanics with Ultracold Atoms

    CERN Document Server

    Purdy, T P; Botter, T; Brahms, N; Ma, Z -Y; Stamper-Kurn, D M

    2010-01-01

    We present an atom-chip-based realization of quantum cavity optomechanics with cold atoms localized within a Fabry-Perot cavity. Effective sub-wavelength positioning of the atomic ensemble allows for tuning the linear and quadratic optomechanical coupling parameters, varying the sensitivity to the displacement and strain of a compressible gaseous cantilever. We observe effects of such tuning on cavity optical nonlinearity and optomechanical frequency shifts, providing their first characterization in the quadratic-coupling regime.