Science.gov

Sample records for gain energy amplifier

  1. A high gain energy amplifier operated with fast neutrons

    SciTech Connect

    Rubbia, C.

    1995-10-01

    The basic concept and the main practical considerations of an Energy Amplifier (EA) have been exhaustively described elsewhere. Here the concept of the EA is further explored and additional schemes are described which offer a higher gain, a larger maximum power density and an extended burn-up. All these benefits stem from the use of fast neutrons, instead of thermal or epithermal ones, which was the case in the original study. The higher gain is due both to a more efficient high energy target configuration and to a larger, practical value of the multiplication factor. The higher power density results from the higher permissible neutron flux, which in turn is related to the reduced rate of {sup 233}Pa neutron captures (which, as is well known, suppress the formation of the fissile {sup 233}U fuel) and the much smaller k variations after switch-off due to {sup 233}Pa decays for a given burn-up rate. Finally a longer integrated burn-up is made possible by reduced capture rate by fission fragments of fast neutrons. In practice a 20 MW proton beam (20 mA @ 1 GeV) accelerated by a cyclotron will suffice to operate a compact EA at the level of {approx} 1 GW{sub e}. The integrated fuel burn-up can be extended in excess of 100 GW d/ton, limited by the mechanical survival of the fuel elements. Radio-Toxicity accumulated at the end of the cycle is found to be largely inferior to the one of an ordinary Reactor for the same energy produced. Schemes are proposed which make a {open_quotes}melt-down{close_quotes} virtually impossible. The conversion ratio, namely the rate of production of {sup 233}U relative to consumption is generally larger than unity, which permits production of fuel for other uses. Alternatively the neutron excess can be used to transform unwanted {open_quotes}ashes{close_quotes} into more acceptable elements.

  2. Microsecond gain-switched master oscillator power amplifier (1958 nm) with high pulse energy

    SciTech Connect

    Ke Yin; Weiqiang Yang; Bin Zhang; Ying Li; Jing Hou

    2014-02-28

    An all-fibre master oscillator power amplifier (MOPA) emitting high-energy pulses at 1958 nm is presented. The seed laser is a microsecond gain-switched thulium-doped fibre laser (TDFL) pumped with a commercial 1550-nm pulsed fibre laser. The TDFL operates at a repetition rate f in the range of 10 to 100 kHz. The two-stage thulium-doped fibre amplifier is built to scale the energy of the pulses generated by the seed laser. The maximum output pulse energy higher than 0.5 mJ at 10 kHz is achieved which is comparable with the theoretical maximum extractable pulse energy. The slope efficiency of the second stage amplifier with respect to the pump power is 30.4% at f = 10 kHz. The wavelength of the output pulse laser is centred near 1958 nm at a spectral width of 0.25 nm after amplification. Neither nonlinear effects nor significant amplified spontaneous emission (ASE) is observed in the amplification experiments. (lasers)

  3. Laser-amplifier gain and noise

    NASA Astrophysics Data System (ADS)

    Loudon, R.; Harris, M.; Shepherd, T. J.; Vaughan, J. M.

    1993-07-01

    A theoretical study is presented of the gain and the noise spectra of laser amplifiers at pumping rates both above and below the oscillation threshold. The theory is valid for both class-A and class-B laser systems, where the decay rate of the collective atomic dipole moment greatly exceeds the decay rates of the atomic population inversion and the laser cavity. The gain and the noise properties are shown to be strongly influenced by a four-wave mixing of the signal and image frequencies via a modulation of the population inversion. Particular attention is paid to the residual noise flux that persists in the laser output above threshold and to the typical characteristics of a second-order phase transition displayed by the gain in the threshold region. The results for the above-threshold laser amplifier are compared with experimental measurements of both gain and noise for the argon-ion (class-A) and CO2 (class-B) lasers. The signal-to-noise ratios for both heterodyne and direct-detection measurements are evaluated, and the conditions are determined under which optical amplification can lead to an enhancement of sensitivity.

  4. Variable Gain Semiconductor Optical Linear Amplifier (OLA)

    NASA Astrophysics Data System (ADS)

    Michie, W. Craig; Kelly, Tony; Tomlinson, Andy; Andonovic, Ivan

    2002-12-01

    The semiconductor optical amplifier (SOA) is a versatile component that can be deployed to meet the expanding applications associated with the introduction of additional functionalities at the optical level in wavelength division multiplexed systems. The future network requires low cost, small footprint, directly controllable amplification throughout the different application layers from long haul through to metro; the intrinsic size and integration capability advantages will ensure that the SOA plays a key role in this evolution. In multi-wavelength gating/amplification applications the gain dynamics, oscillating at timescales comparable to that of the data which is being amplified, introduce issues of pattern dependent waveform distortion (patterning) in single channel, and inter-channel cross-talk in multi-wavelength cases which require management through careful SOA design and understanding of the network application scenarios. In this paper, an optical linear amplifier (OLA) architecture with the unique capability to provide variable gain whilst maintaining linear operation at high output saturation powers will be described. Initial characterisation results for the OLA will be presented.

  5. Theory of noise in high-gain surface plasmon-polariton amplifiers incorporating dipolar gain media.

    PubMed

    De Leon, Israel; Berini, Pierre

    2011-10-10

    A theoretical analysis of noise in high-gain surface plasmon-polariton amplifiers incorporating dipolar gain media is presented. An expression for the noise figure is obtained in terms of the spontaneous emission rate into the amplified surface plasmon-polariton taking into account the different energy decay channels experienced by dipoles in close proximity to the metallic surface. Two amplifier structures are examined: a single-interface between a metal and a gain medium and a thin metal film bounded by identical gain media on both sides. A realistic configuration is considered where the surface plasmon-polariton undergoing amplification has a Gaussian field profile in the plane of the metal and paraxial propagation along the amplifier's length. The noise figure of these plasmonic amplifiers is studied considering three prototypical gain media with different permittivities. It is shown that the noise figure exhibits a strong dependance on the real part of the permittivities of the metal and gain medium, and that its minimum value is 4/π(∼3.53 dB). The origin of this minimum value is discussed. It is also shown that amplifier configurations supporting strongly confined surface plasmon-polaritons suffer from a large noise figure, which follows from an enhanced spontaneous emission rate due to the Purcell effect.

  6. Use of a photonic crystal for optical amplifier gain control

    DOEpatents

    Lin, Shawn-Yu; Fleming, James G.; El-Kady, Ihab

    2006-07-18

    An optical amplifier having a uniform gain profile uses a photonic crystal to tune the density-of-states of a gain medium so as to modify the light emission rate between atomic states. The density-of-states of the gain medium is tuned by selecting the size, shape, dielectric constant, and spacing of a plurality of microcavity defects in the photonic crystal. The optical amplifier is particularly useful for the regeneration of DWDM signals in long optical fibers.

  7. Design gain characteristic of dual-pump fiber Raman amplifier

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Zhang, Wei; Liu, Xiaoming; Peng, Jiangde; Zhou, BingKun

    2001-10-01

    To design gain characteristic of dual-pump fiber Raman amplifier, an effect optimal model is investigated under different conditions, such as maximal gain and minimal gain ripper. Impact of pumps interaction, pump wavelength selection, signals interaction and signal saturation are discussed.

  8. Crystal oscillators using negative voltage gain, single pole response amplifiers

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L. (Inventor)

    1989-01-01

    A simple and inexpensive crystal oscillator is provided which employs negative voltage gain, single pole response amplifiers. The amplifiers may include such configurations as gate inverters, operational amplifiers and conventional bipolar transistor amplifiers, all of which operate at a frequency which is on the roll-off portion of their gain versus frequency curve. Several amplifier feedback circuit variations are employed to set desired bias levels and to allow the oscillator to operate at the crystal's fundamental frequency or at an overtone of the fundamental frequency. The oscillator is made less expensive than comparable oscillators by employing relatively low frequency amplifiers and operating them at roll-off, at frequencies beyond which they are customarily used. Simplicity is provided because operation at roll-off eliminates components ordinarily required in similar circuits to provide sufficient phase-shift in the feedback circuitry for oscillation to occur.

  9. Development of a 233 GHz High Gain Traveling Wave Amplifier

    DTIC Science & Technology

    2014-04-22

    USA 2Beam Wave Research, Inc., Bethesda, MD 20814 USA Abstract: We present development plans for a 233 GHz, serpentine waveguide vacuum electron...NRL G-band serpentine waveguide amplifier [2, 3] was the first demonstrated amplifier to use a UV-LIGA fabricated circuit. The small- signal gain...using the same techniques for 231.5 GHz to 235 GHz, an FCC Radiolocation band. Amplifier Design The compound, hybrid serpentine waveguide (SWG

  10. Theory of laser-amplifier linear gain

    NASA Astrophysics Data System (ADS)

    Jahanpanah, J.; Loudon, R.

    1997-09-01

    The theory of small-signal laser amplification is developed for homogeneously broadened systems in which the three main decay rates, for the collective atomic dipole moment, the population inversion, and the field in the laser cavity, have arbitrary relative magnitudes. The calculations extend previous work on class-A and -B lasers, where the dipole decay rate greatly exceeds the other two rates, to class-C lasers, where the dipole decay rate is comparable to the others. The free-running laser is assumed to excite a single longitudinal mode of the cavity, whose frequency generally differs from that of the coupled atomic transition. The linear gains of the laser are derived for input signals whose frequencies are close to that of the lasing mode or to one of its adjacent nonlasing longitudinal modes. Divergences in the gain that occur for these two arrangements are associated with the previously studied single-mode and multimode instabilities of the free-running laser, respectively.

  11. 62-dB-gain multiple-pass slab geometry Nd:YAG amplifier

    NASA Technical Reports Server (NTRS)

    Kane, T. J.; Kozlovsky, W. J.; Byer, R. L.

    1986-01-01

    A flash-lamp-pumped slab Nd:YAG laser amplifier with 62 dB of gain is demonstrated. The amplifier remains linear for energy extraction up to 12 mJ, and the beam spatial quality remains good at repetition rates up to 10 Hz. The slab geometry provides for gain averaging in the zigzag dimension, thus eliminating the undesirable effects of nonuniform pumping. This averaging and the necessity for only a single compact gain element are valuable attributes that may allow for eventual laser-diode array pumping of the slab Nd:YAG amplifier.

  12. Background Rates of Gain Amplifying Detectors in Space

    NASA Astrophysics Data System (ADS)

    MacDonald, E.; Avanov, L. A.; Gliese, U.; Pollock, C. J.; Giles, B. L.; Funsten, H. O.; Larsen, B.; Skoug, R. M.; Gershman, D. J.; Barrie, A. C.; Coffey, V. N.; Chandler, M. O.; Mauk, B.; Dorelli, J.; Rager, A. C.

    2015-12-01

    In the near Earth space environment plasma instruments utilize gain multiplying detectors such as microchannel plates (MCPs) or channel electron multipliers (CEMs) to amplify single impacting particles into countable electronic pulses. These detectors also respond to higher energy particles such as penetrating MeV electron and proton radiation. Such background signals can be significant enough to be confused with foreground signals of interest in environments like Earth or Jovian radiation belts. It is thus critically important to fully understand the sensitivity of MCP and CEM detectors in situ. In the lab, MCPs are estimated to be ~ 20 times more sensitive per unit input area than CEMs. We will compare the background rates for two recent instruments, the Helium Oxygen Proton Electron (HOPE) mass spectrometer for the Van Allen Probes, and the Fast Plasma Investigation (FPI) instrument suite on the Magnetospheric Multiscale Mission to their respective penetrating radiation environment and estimate the relative response rates for these two types of detectors.

  13. Multilayered Waveguides for Increasing the Gain Bandwidth of Integrated Amplifiers

    NASA Astrophysics Data System (ADS)

    Laliotis, Athanasios; Yeatman, Eric M.

    2007-06-01

    In this paper, we propose and demonstrate the use of multilayered (laminated) waveguides for increasing the available gain spectrum of sol gel amplifiers. Experimental investigations of the effects of phosphorus codoping on the amplifier spectral characteristics and fluorescence decay are also presented. We demonstrate that the shape of the erbium emission cross section, for aluminophosphosilicate amplifiers, has a minor dependence on the amount of phosphorus doping and that spectral benefits are only achieved for aluminosilicate amplifiers, albeit with low levels of erbium inversion. Laminated amplifiers, consisting of alternating layers of two compositions, are shown to display novel spectral characteristics that cannot be obtained by the use of single composition cores. Internal gain, which is demonstrated for this device, also suggests that erbium inversion can be maintained at relatively high levels. Experimental results are supported by numerical analysis, and a 20-nm bandwidth increase is observed for laminated amplifiers, with gain levels up to 1.4 dB/cm indicated, when processing conditions are optimized.

  14. High gain amplifiers: Power oscillations and harmonic generation

    SciTech Connect

    Dattoli, G.; Ottaviani, P. L.; Pagnutti, S.

    2007-08-01

    We discuss the power oscillations in saturated high gain free electron laser amplifiers and show that the relevant period can be written in terms of the gain length. We use simple arguments following from the solution of the pendulum equation in terms of Jacobi elliptic functions. Nontrivial effects due to nonlinear harmonic generation and inhomogeneous broadening are discussed too, as well as the saturated dynamics of short pulses.

  15. Tradeoff on gain-flatness and gain-stabilization of erbium doped fiber amplifier with FBGs

    NASA Astrophysics Data System (ADS)

    Buyin, Garidi; OuYang, Yunlun; Ma, Yu; Chang, Jinlong; Liu, Changxing; Yang, Jiuru

    2014-07-01

    It is a challenge to get gain-stabilization and gain-flatness of erbium doped fiber amplifier (EDFA) in C-band, simultaneously. In this article, we establish a gain-clamped EDFA model based uniform fiber grating-pair and optimize the reflectivity of grating by the designed targets. The tradeoff between stabilization and flatness can be obtained when an ideal reflectivity is adopted. The numerical results show that the gain-stabilization is controlled in +/-0.1dB and gain-flatness is less than +/-1.41dB in the range from 1535nm to 1565nm.

  16. Cathode driven high gain crossed-field amplifier

    NASA Astrophysics Data System (ADS)

    1983-07-01

    The objective of this three-phase program is to achieve the design of a cathode driven high gain re-entrant Crossed Field Amplifier capable of meeting the parameters of Raytheon Company specification No. 968838 dated 10 May 1978. The effort includes the fabrication and test of three developmental and four final configuration tubes. One final configuration tube will be life tested and two will be delivered to the Navy. The tasks discussed during this report period relate to the cold tests performed on various subassemblies of model no. 4 and on the sealed-in model no. 4 of the S-band high gain cathode driven crossed field amplifier. Based on the performance of model no. 3 certain remedial measures have been implemented in model no. 4 that have resulted in the elimination of key resonances within the tube and an improvement in the isolation between the cathode and anode circuits.

  17. High gain pre-amplifier laser beam quality evaluating system

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Yu, Jin; Zhao, Tianzhuo; Zhang, Xue; Fan, Zhongwei

    2011-06-01

    Designed a system for the high gain laser pre-amplifier to evaluate the image quality. The system uses 4f imaging principle and Kepler type telescope was choiced, it has two advantages: avert optical distortion and eliminate aberration in the measurement system. Combined with the location of the lens inside of pre-amplifier such as the spatial filter , the near field imaging structure was designed. The structure can be reduced to 11.9 times the beam image, and clearly passed the image to the CCD target surface. The location of first positive lens focus is the location of far field image. In this article, one laser pre-amplifier was measured. The average measured near field modulation M=1.34, the average measured far field diffraction limit is 2.94. Experiments show that the stability of measuring system is less than+/-5%, it can meet the measurement requirements of ICF laser pre-amplifier parameters. Use this system we can discover the problem during the design and installation. There is great meaning for develop of laser pre-amplifier in ICF for further.

  18. High-gain cryogenic amplifier assembly employing a commercial CMOS operational amplifier.

    PubMed

    Proctor, J E; Smith, A W; Jung, T M; Woods, S I

    2015-07-01

    We have developed a cryogenic amplifier for the measurement of small current signals (10 fA-100 nA) from cryogenic optical detectors. Typically operated with gain near 10(7) V/A, the amplifier performs well from DC to greater than 30 kHz and exhibits noise level near the Johnson limit. Care has been taken in the design and materials to control heat flow and temperatures throughout the entire detector-amplifier assembly. A simple one-board version of the amplifier assembly dissipates 8 mW to our detector cryostat cold stage, and a two-board version can dissipate as little as 17 μW to the detector cold stage. With current noise baseline of about 10 fA/(Hz)(1/2), the cryogenic amplifier is generally useful for cooled infrared detectors, and using blocked impurity band detectors operated at 10 K, the amplifier enables noise power levels of 2.5 fW/(Hz)(1/2) for detection of optical wavelengths near 10 μm.

  19. Gain dynamics measurement in injection-seeded soft x-ray laser plasma amplifiers

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Wang, S.; Li, L.; Oliva, E.; Thuy Le, T. T.; Ros, D.; Berrill, M.; Dunn, J.; Zeitoun, Ph.; Yin, L.; Luther, B.; Rocca, J. J.

    2013-10-01

    Herein we report the first measurement of the gain dynamics in a soft x-ray plasma amplifier seeded by high harmonic pulses. A sequence of two time-delayed spatially-overlapping high harmonic pulses was injected into a λ = 18.9 nm Ni-like Mo plasma amplifier to measure the regeneration of the population inversion that follows the gain depletion caused by the amplification of the first seed pulse. Collisional excitation is observed to re-establish population inversion depleted during the amplification of the seed pulse in about ~1.75 ps. The measured gain-recovery time is compared to model simulations to gain insight on the population inversion mechanisms that create the transient gain in these amplifiers. This result supports the concept of a soft x-ray laser amplification scheme based on the continuous extraction of energy from a soft x-ray plasma-based amplifier by an stretched seed pulse has the potential to generate ultra-intense fully phase-coherent soft x-ray laser pulses. Work supported by AMOS program, Office of Basic Energy Sciences of the US DoE, and the NSF ERC Program with equipment developed under NSF Award MRI-ARRA 09-561, and by LASERLAB3-INREX European project and SHYLAX plus CIBORG RTRA `Triangle de la Physique.'

  20. Gain and energy storage in holmium YLF

    NASA Technical Reports Server (NTRS)

    Storm, Mark E.; Deyst, John P.

    1991-01-01

    It is demonstrated that Q-switched holmium lasers are capable of high-gain and high-energy operation at 300 K. Small-signal gain coefficients of 0.50 and 0.12/cm have been measured in YLF and YAG, respectively. Small-signal gains of 0.50/cm are comparable to those achievable in Nd:YAG and are not typical of low-gain materials. This large gain in the Ho:YLF material is made possible by operating the amplifier in the ground state depletion mode. The amplifier performance data and associated analysis presented demonstrate that efficient energy storage is possible with very high excited state ion densities of the Ho 5I7 upper laser level. This is an important result since upconversion can limit the 5I7 population. Although upconversion was still present in this experiment, it was possible to achieve efficient energy storage, demonstrating that the problem is manageable even at high excitation densities in YLF.

  1. An ultra-high gain and efficient amplifier based on Raman amplification in plasma.

    PubMed

    Vieux, G; Cipiccia, S; Grant, D W; Lemos, N; Grant, P; Ciocarlan, C; Ersfeld, B; Hur, M S; Lepipas, P; Manahan, G G; Raj, G; Reboredo Gil, D; Subiel, A; Welsh, G H; Wiggins, S M; Yoffe, S R; Farmer, J P; Aniculaesei, C; Brunetti, E; Yang, X; Heathcote, R; Nersisyan, G; Lewis, C L S; Pukhov, A; Dias, J M; Jaroszynski, D A

    2017-05-25

    Raman amplification arising from the excitation of a density echelon in plasma could lead to amplifiers that significantly exceed current power limits of conventional laser media. Here we show that 1-100 J pump pulses can amplify picojoule seed pulses to nearly joule level. The extremely high gain also leads to significant amplification of backscattered radiation from "noise", arising from stochastic plasma fluctuations that competes with externally injected seed pulses, which are amplified to similar levels at the highest pump energies. The pump energy is scattered into the seed at an oblique angle with 14 J sr(-1), and net gains of more than eight orders of magnitude. The maximum gain coefficient, of 180 cm(-1), exceeds high-power solid-state amplifying media by orders of magnitude. The observation of a minimum of 640 J sr(-1) directly backscattered from noise, corresponding to ≈10% of the pump energy in the observation solid angle, implies potential overall efficiencies greater than 10%.

  2. An ultra-high gain and efficient amplifier based on Raman amplification in plasma

    DOE PAGES

    Vieux, G.; Cipiccia, S.; Grant, D. W.; ...

    2017-05-25

    Raman amplification arising from the excitation of a density echelon in plasma could lead to amplifiers that significantly exceed current power limits of conventional laser media. Here we show that 1–100 J pump pulses can amplify picojoule seed pulses to nearly joule level. The extremely high gain also leads to significant amplification of backscattered radiation from “noise”, arising from stochastic plasma fluctuations that competes with externally injected seed pulses, which are amplified to similar levels at the highest pump energies. The pump energy is scattered into the seed at an oblique angle with 14 J sr-1, and net gains ofmore » more than eight orders of magnitude. The maximum gain coefficient, of 180 cm-1, exceeds high-power solid-state amplifying media by orders of magnitude. The observation of a minimum of 640 J sr-1 directly backscattered from noise, corresponding to ≈10% of the pump energy in the observation solid angle, implies potential overall efficiencies greater than 10%.« less

  3. Gain measurements on a waveguide FEL amplifier with pre-bunched electron beam

    SciTech Connect

    Dearden, G.; Mayhew, S.E.; Lucas, J.

    1995-12-31

    A theory proposed by Doria et al. suggests that a synchronous pre-bunched electron beam should amplify radiation with a power gain which is inversely proportional to the square root of the input power. We have measured the power gain experimentally for a waveguide FEL system using a low-voltage (55kV) pre-bunched electron beam produced by a waveguide cavity buncher. The gain has been observed as a function of the electron beam current and energy; the results are compared with theory.

  4. Exponential gain and saturation of a self-amplified spontaneous emission free-electron laser.

    PubMed

    Milton, S V; Gluskin, E; Arnold, N D; Benson, C; Berg, W; Biedron, S G; Borland, M; Chae, Y C; Dejus, R J; Den Hartog, P K; Deriy, B; Erdmann, M; Eidelman, Y I; Hahne, M W; Huang, Z; Kim, K J; Lewellen, J W; Li, Y; Lumpkin, A H; Makarov, O; Moog, E R; Nassiri, A; Sajaev, V; Soliday, R; Tieman, B J; Trakhtenberg, E M; Travish, G; Vasserman, I B; Vinokurov, N A; Wang, X J; Wiemerslage, G; Yang, B X

    2001-06-15

    Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report on the demonstration of self-amplified spontaneous emission gain, exponential growth, and saturation at visible (530 nanometers) and ultraviolet (385 nanometers) wavelengths. Good agreement between theory and simulation indicates that scaling to much shorter wavelengths may be possible. These results confirm the physics behind the self-amplified spontaneous emission process and forward the development of an operational x-ray free-electron laser.

  5. Gain-shift induced by dopant concentration ratio in a Thulium-Bismuth doped fiber amplifier.

    PubMed

    Emami, Siamak Dawazdah; Zarifi, Atieh; Rashid, Hairul Azhar Abdul; Muhammad, Ahmad Razif; Paul, Mukul Chandra; Halder, Arindam; Bhadra, Shyamal Kumar; Ahmad, Harith; Harun, Sulaiman Wadi

    2014-03-24

    This paper details the effect of Thulium and Bismuth concentration ratio on gain-shift at 1800 nm and 1400 nm band in a Thulium-Bismuth Doped Fiber Amplifier (TBDFA). The effect of Thulium and Bismuth's concentration ratio on gain shifting is experimentally established and subsequently numerically modeled. The analysis is carried out via the cross relaxation and energy transfer processes between the two dopants. The energy transfer in this process was studied through experimental and numerical analysis of three samples with different Tm/Bi concentration ratio of 2, 0.5 and 0.2, respectively. The optimized length for the three samples (TBDFA-1, TBDFA-2 and TBDFA-3) was determined and set at 6.5, 4 and 5.5 m, respectively. In addition, the experimental result of Thulium Doped Fiber Amplifier (TDFA) was compared with the earlier TBDFA samples. The gain for TBDFA-1, with the highest Tm/Bi ratio, showed no shift at the 1800 nm region, while TBDFA-2 and TBDFA-3, possessing a lower Tm/Bi concentration ratio, shifted to the region of 1950 and 1960 nm, respectively. The gain shifting from 1460 nm to 1490 nm is also observed. The numerical model demonstrates that the common 3F4 layer for 1460 nm emission (3H4→3F4), and 1800 nm emission (3F4→3H6)inversely affects the 1460 nm and 1800 nm gain shifting.

  6. Two stage dual gate MESFET monolithic gain control amplifier for Ka-band

    NASA Astrophysics Data System (ADS)

    Sokolov, V.; Geddes, J.; Contolatis, A.

    A monolithic two stage gain control amplifier has been developed using submicron gate length dual gate MESFETs fabricated on ion implanted material. The amplifier has a gain of 12 dB at 30 GHz with a gain control range of over 30 dB. This ion implanted monolithic IC is readily integrable with other phased array receiver functions such as low noise amplifiers and phase shifters.

  7. Static gain saturation in quantum dot semiconductor optical amplifiers.

    PubMed

    Meuer, Christian; Kim, Jungho; Laemmlin, Matthias; Liebich, Sven; Capua, Amir; Eisenstein, Gadi; Kovsh, Alexey R; Mikhrin, Sergey S; Krestnikov, Igor L; Bimberg, Dieter

    2008-05-26

    Measurements of saturated amplified spontaneous emission-spectra of quantum dot semiconductor optical amplifiers demonstrate efficient replenishment of the quantum-dot ground state population from excited states. This saturation behavior is perfectly modeled by a rate equation model. We examined experimentally the dependence of saturation on the drive current and the saturating optical pump power as well as on the pump wavelength. A coherent noise spectral hole is observed with which we assess dynamical properties and propose optimization of the SOA operating parameters for high speed applications.

  8. A High Efficiency Variable Gain Amplifier Circuit with Controllable Transconductance Amp

    NASA Astrophysics Data System (ADS)

    Okura, Tetsuro; Okura, Shunsuke; Ido, Toru; Taniguchi, Kenji

    A novel power reduction technique for a variable gain amplifier (VGA) with a two-stage operational amplifier is proposed. The technique improves the power consumption of a VGA by optimizing the bandwidth and the phase margin dynamically on all gain range of the VGA through controlling the input transconductance of opamp. A VGA utilizing the proposed technique shows 40% reduction of power consumption against a conventional VGA at the best condition of VGA gain range.

  9. Approaching Quantum-Limited Amplification with Large Gain Catalyzed by Optical Parametric Amplifier Medium

    NASA Astrophysics Data System (ADS)

    Zheng, Qiang; Li, Kai

    2017-07-01

    Amplifier is at the heart of experiments carrying out the precise measurement of a weak signal. An idea quantum amplifier should have a large gain and minimum added noise simultaneously. Here, we consider the quantum measurement properties of the cavity with the OPA medium in the op-amp mode to amplify an input signal. We show that our nonlinear-cavity quantum amplifier has large gain in the single-value stable regime and achieves quantum limit unconditionally. Supported by the National Natural Science Foundation of China under Grant Nos. 11365006, 11364006, and the Natural Science Foundation of Guizhou Province QKHLHZ [2015]7767

  10. Research on gain uniformity of the laser non-imaging rod amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Yongzhong; Zhu, Jianqiang

    2015-08-01

    According to the problem of gain medium cross section high illumination and non-uniformity, which is caused by the laser rod amplifier non-imaging pump style. Orthogonal test design method is used to research the effect of absorption coefficient, gain medium radius, number of xenon lamps, center distance of xenon lamps and gain medium on gain uniformity. The rod amplifier which is made up by the above four elements, its gain medium cross section illumination distribution is simulated by ASAP. The results show that center distance of xenon lamps and gain medium, number of xenon lamps have very little influence on the gain uniformity. When absorption coefficient equal to 5.1 cm-1, gain uniformity will reach the optimum. Under the circumstance of other three elements are equal, the bigger is the gain radius, the smaller slope reflection curve, and the better gain uniformity.

  11. Simplified ASE correction algorithm for variable gain-flattened erbium-doped fiber amplifier.

    PubMed

    Mahdi, Mohd Adzir; Sheih, Shou-Jong; Adikan, Faisal Rafiq Mahamd

    2009-06-08

    We demonstrate a simplified algorithm to manifest the contribution of amplified spontaneous emission in variable gain-flattened Erbium-doped fiber amplifier (EDFA). The detected signal power at the input and output ports of EDFA comprises of both signal and noise. The generated amplified spontaneous emission from EDFA cannot be differentiated by photodetector which leads to underestimation of the targeted gain value. This gain penalty must be taken into consideration in order to obtain the accurate gain level. By taking the average gain penalty within the dynamic gain range, the targeted output power is set higher than the desired level. Thus, the errors are significantly reduced to less than 0.15 dB from 15 dB to 30 dB desired gain values.

  12. Time Difference Amplifier with Robust Gain Using Closed-Loop Control

    NASA Astrophysics Data System (ADS)

    Nakura, Toru; Mandai, Shingo; Ikeda, Makoto; Asada, Kunihiro

    This paper presents a Time Difference Amplifier (TDA) that amplifies the input time difference into the output time difference. Cross coupled chains of variable delay cells with the same number of stages are applicable for TDA, and the gain is adjusted via the closed-loop control. The TDA was fabricated using 65nm CMOS and the measurement results show that the time difference gain is 4.78 at a nominal power supply while the designed gain is 4.0. The gain is stable enough to be less than 1.4% gain shift under ±10% power supply voltage fluctuation.

  13. Mode instability in high power all-fiber amplifier with large-mode-area gain fiber

    NASA Astrophysics Data System (ADS)

    Wang, Jianming; Yan, Dapeng; Xiong, Songsong; Huang, Bao; Li, Cheng

    2017-08-01

    We studied the mode instability (MI) of the signal light in high power all-fiber amplifier with large-mode-area (LMA) gain fiber experimentally. The MI phenomenon of the output beam was observed and analyzed in the all-fiber amplifier, and the MI power threshold was compared by coiling gain fiber with different radii in multi-kilowatt level (more than 3 kW). In the experiments, MI power threshold was improved and optimized with coil radius reduction of the LMA gain fiber in the all-fiber amplifier.

  14. Optoelectronic gain control of a microwave single stage GaAs MESFET amplifier

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    1988-01-01

    Gain control of a single stage GaAs MESFET amplifier is demonstrated by the use of optical illumination of photon energy greater than the GaAs bandgap. The optical illumination is supplied by a semiconductor laser diode and is coupled to the Schottky gate of the MESFET by an optical fiber. The increase in gain is observed to be as much as 5.15 dB when the MESFET is biased close to pinchoff, that is, V(sub gs) equals -1.5 V and with optical illumination of 1.5 mW. The computed maximum available gain (MAG) and current gain (bar h sub 21 bar) from the de-embedded s-parameters show that MAG is unaffected by optical illumination, however, bar h(sub 21)bar increases by more than 2 dB under optical illumination of 1.5 mW. The maximum frequency of oscillation (F sub max) and the unity current gain cut-off frequency (F sub t) obtained by extrapolating the MAG and bar h(sub 21)bar curves, respectively, show that the F(sub max) is insensitive to optical illumination but F(sub t) increases by 5 GHz.

  15. MMIC Amplifier Produces Gain of 10 dB at 235 GHz

    NASA Technical Reports Server (NTRS)

    Dawson, Douglas; Fung, King Man; Lee, Karen; Samoska, Lorene; Wells, Mary; Gaier, Todd; Kangaslahti, Pekka; Grundbacher, Ronald; Lai, Richard; Raja, Rohit; Liu, Po-Hsin

    2007-01-01

    The first solid-state amplifier capable of producing gain at a frequency >215 GHz has been demonstrated. This amplifier was fabricated as a monolithic microwave integrated-circuit (MMIC) chip containing InP high-electron-mobility transistors (HEMTs) of 0.07 micron gate length on a 50- m-thick InP substrate.

  16. Design of a high-gain laser diode-array pumped Nd:YAG alternating precessive slab amplifier (APS amplifier)

    NASA Technical Reports Server (NTRS)

    Coyle, D. B.

    1991-01-01

    In the design of space-qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. A novel preamplifier design is examined which requires no external beam steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium.

  17. Design of a high-gain laser diode-array pumped Nd:YAG alternating precessive slab amplifier (APS amplifier)

    NASA Technical Reports Server (NTRS)

    Coyle, D. B.

    1991-01-01

    In the design of space-qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. A novel preamplifier design is examined which requires no external beam steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium.

  18. Optical Amplifier with Flat-Gain and Wideband Operation Utilizing Highly Concentrated Erbium-Doped Fibers

    NASA Astrophysics Data System (ADS)

    Hamida, B. A.; Cheng, X. S.; Naji, A. W.; Ahmad, H.; Al-Khateeb, W.; Khan, S.; Harun, S. W.

    In this paper, we proposed a flat-gain and wide-band erbium doped fiber amplifier (EDFA) using two chirped fiber Bragg grating (CFBG) in serial configuration for double-pass operation. The amplifier consists of two sections of Erbium-doped fiber (EDF) operating in C-band and L-band respectively. A CFBG is used in each section to reflect the amplified signal back to the active area so that the overall gain spectrum can be enhanced and flattened. It is also observed that the gain of the amplifier produces a relatively higher gain with the Bismuth-based EDF (Bi-EDF) in the first stage compared to that of silica-based EDF (Si-EDF), especially in a longer wavelength region. The small signal gain of more than 19 dB is obtained within a wavelength region from 1545 to 1605 nm by the use of Bi-EDF with a small noise figure penalty. With a Si-EDF, the flat gain spectrum is observed within a wavelength region ranging from 1535 nm to 1605 nm with a gain variation of less than 2 dB at input signal of 0 dBm. This shows that the proposed serial double-pass amplifier may find its broad applications in wavelength division multiplexing long-haul systems as well as local optical networks.

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

    SciTech Connect

    Xie, M.; Kim, K.J.

    1995-12-31

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

  20. Slow and fast dynamics of gain and phase in a quantum dot semiconductor optical amplifier.

    PubMed

    Vallaitis, T; Koos, C; Bonk, R; Freude, W; Laemmlin, M; Meuer, C; Bimberg, D; Leuthold, J

    2008-01-07

    Gain and phase dynamics in InAs/GaAs quantum dot semiconductor optical amplifiers are investigated. It is shown that gain recovery is dominated by fast processes, whereas phase recovery is dominated by slow processes. Relative strengths and time constants of the underlying processes are measured. We find that operation at high bias currents optimizes the performance for nonlinear cross-gain signal processing if a low chirp is required.

  1. High-gain weakly nonlinear flux-modulated Josephson parametric amplifier using a SQUID array

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Schmitt, V.; Bertet, P.; Vion, D.; Wustmann, W.; Shumeiko, V.; Esteve, D.

    2014-06-01

    We have developed and measured a high-gain quantum-limited microwave parametric amplifier based on a superconducting lumped LC resonator with the inductor L including an array of eight superconducting quantum interference devices (SQUIDs). This amplifier is parametrically pumped by modulating the flux threading the SQUIDs at twice the resonator frequency. Around 5 GHz, a maximum gain of 31 dB, a product amplitude gain × bandwidth above 60 MHz, and a 1 dB compression point of -123 dBm at 20 dB gain are obtained in the nondegenerate mode of operation. Phase-sensitive amplification-deamplification is also measured in the degenerate mode and yields a maximum gain of 37 dB. The compression point obtained is 18 dB above what would be obtained with a single SQUID of the same inductance, due to the smaller nonlinearity of the SQUID array.

  2. Gain recovery dynamics in semiconductor optical amplifiers with distributed feedback grating under assist light injection

    NASA Astrophysics Data System (ADS)

    Qin, Cui; Zhao, Jing; Yu, Huilong; Zhang, Jian

    2016-07-01

    The gain recovery dynamic characteristics of the semiconductor optical amplifier (SOA) with distributed feedback (DFB) grating are theoretically investigated. The interaction of the grating structure and the assist light is used to accelerate the gain recovery process in the SOA. The effects of the assist light that is injected into the SOA with DFB structure on the gain recovery dynamics, the steady-state carrier density, and field intensity distributions are analyzed, respectively. Results show that the recovery time in the DFB SOA is successfully reduced by injecting relatively high power assist light, whose wavelength is set at the gain region. Finally, under assist light injection, the effects of DFB grating on the gain recovery process are also discussed. It is shown that the gain recovery in the SOA with DFB grating is faster than that in the SOA without DFB grating. In addition, the coupling factor in the DFB grating structure can be optimized to shorten the gain recovery time.

  3. Programmable gain amplifiers with DC suppression and low output offset for bioelectric sensors.

    PubMed

    Carrera, Albano; de la Rosa, Ramón; Alonso, Alonso

    2013-09-27

    DC-offset and DC-suppression are key parameters in bioelectric amplifiers. However, specific DC analyses are not often explained. Several factors influence the DC-budget: the programmable gain, the programmable cut-off frequencies for high pass filtering and, the low cut-off values and the capacitor blocking issues involved. A new intermediate stage is proposed to address the DC problem entirely. Two implementations were tested. The stage is composed of a programmable gain amplifier (PGA) with DC-rejection and low output offset. Cut-off frequencies are selectable and values from 0.016 to 31.83 Hz were tested, and the capacitor deblocking is embedded in the design. Hence, this PGA delivers most of the required gain with constant low output offset, notwithstanding the gain or cut-off frequency selected.

  4. Programmable Gain Amplifiers with DC Suppression and Low Output Offset for Bioelectric Sensors

    PubMed Central

    Carrera, Albano; de la Rosa, Ramón; Alonso, Alonso

    2013-01-01

    DC-offset and DC-suppression are key parameters in bioelectric amplifiers. However, specific DC analyses are not often explained. Several factors influence the DC-budget: the programmable gain, the programmable cut-off frequencies for high pass filtering and, the low cut-off values and the capacitor blocking issues involved. A new intermediate stage is proposed to address the DC problem entirely. Two implementations were tested. The stage is composed of a programmable gain amplifier (PGA) with DC-rejection and low output offset. Cut-off frequencies are selectable and values from 0.016 to 31.83 Hz were tested, and the capacitor deblocking is embedded in the design. Hence, this PGA delivers most of the required gain with constant low output offset, notwithstanding the gain or cut-off frequency selected. PMID:24084109

  5. Laser aperture diagnostics system for gain and wavefront measurements on NIF/LMJ amplifiers

    SciTech Connect

    Zapata, L. E., LLNL

    1996-12-17

    We are in the midst of constructing an amplifier laboratory (Arnplab) that will be the physics and engineering proving ground for fill sized segmented glass amplifiers of designs that will outfit the National Ignition Facility (NIF) and Laser Megajoule (LMJ) projects. Amplab will demonstrate the cornerstone mechanical, electrical and optical concepts that support the NW and LMJ amplifier schemes. Here we address the optical diagnostics that will be used to characterize optical performance of the amplifiers. We describe, the apparatus that will be used in pulsed measurements of gain distribution and wave-front distortions. The large aperture diagnostic system or LADS, is now being built through a collaborative effort between CEL-V and LLNL. The LADS will provide measurements of gain and wave front distortions over the fill extracting aperture of the NIF and LMJ prototype amplifiers. The LADS will be able to address each of eight apertures via motorized stages and following semi-automated alignment, take data on the aperture of interest. The LADS should be operational in mid-1997 at LLNL and will be used to characterize the optical performance of the very first fill scale prototype 4 x 2 NIF and LMJ amplifiers. It will be transported to Bordeaux, France to make similar measurements during activation of the first 8-aperture LMJ-like facility (LIL) that is planned to start in the near future.

  6. Burst shaping in a fiber-amplifier chain seeded by a gain-switched laser diode.

    PubMed

    Petelin, Jaka; Podobnik, Boštjan; Petkovšek, Rok

    2015-05-20

    A low-power source, such as a gain-switched laser diode, usually requires several amplification stages to reach sufficient power levels. When operating in burst mode, a correct input burst shape must be determined in order to compensate for gain saturation of all amplifier stages. In this paper we report on closed-form equations that enable saturation compensation in multiamplifier setups, which eliminates the need for an adaptive feedback loop. The theoretical model is then evaluated in an experimental setup.

  7. Mode control in a high gain relativistic klystron amplifier with 3 GW output power

    NASA Astrophysics Data System (ADS)

    Wu, Yang; Xie, Hong-Quan; Xu, Zhou

    2014-01-01

    Higher mode excitation is very serious in the relativistic klystron amplifier, especially for the high gain relativistic amplifier working at tens of kilo-amperes. The mechanism of higher mode excitation is explored in the PIC simulation and it is shown that insufficient separation of adjacent cavities is the main cause of higher mode excitation. So RF lossy material mounted on the drift tube wall is adopted to suppress higher mode excitation. A high gain S-band relativistic klystron amplifier is designed for the beam current of 13 kA and the voltage of 1 MV. PIC simulation shows that the output power is 3.2 GW when the input power is only 2.8 kW.

  8. Gain stability in fluorine polymer modified PbS Quantum dot fiber amplifier

    NASA Astrophysics Data System (ADS)

    Liang, Qi; Li, Nana; Zhou, Bin; Zhang, Hanning; Sun, Xiaolan; Kost, Alan R.

    2017-06-01

    The fluorescence intensity drop rate of PbS quantum dot with fluorine-containing polymer is 9.76% and the gain drop rate of quantum dot fiber amplifier (QDFA) with fluorine-containing polymer is 57.66% separately with temperature, which is more stable than no fluorine polymer QDFA.

  9. Optical properties of the output of a high gain, self-amplified free-electron laser.

    SciTech Connect

    Krinsky, S.; Lewellen , J.; Sajaev, V.; Accelerator Systems Division; BNL

    2004-01-01

    The temporal structure and phase evolutions of a high-gain, self-amplified free-electron laser are measured, including single-shot analysis and statistics over many shots. Excellent agreement with the theory of free-electron laser and photon statistics is found.

  10. Segmented dual-gate MESFET's for variable gain and power amplifiers in GaAs MMIC

    NASA Astrophysics Data System (ADS)

    Snow, Keith H.; Komiak, James J.; Bates, David A.

    1988-12-01

    The design and performance of C-, X-, and Ku-band GaAs MMIC variable-gain and variable-power amplifier circuits using an improved segmented dual-gate MESFET device with binary scaled gate width ratios are reported. The demonstrated 35-dB control range, flat octave band gain response, and small incidental phase variation are significantly superior to the reported characteristics of conventional analog controlled devices. The design provides precise amplitude quantization while minimizing phase variations, and thus calibration complexity, incurred by gain switching.

  11. Comparison of pulse propagation and gain saturation characteristics among different input pulse shapes in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Barua, Suchi; Das, Narottam; Nordholm, Sven; Razaghi, Mohammad

    2016-01-01

    This paper presents the pulse propagation and gain saturation characteristics for different input optical pulse shapes with different energy levels in semiconductor optical amplifiers (SOAs). A finite-difference beam propagation method (FD-BPM) is used to solve the modified nonlinear Schrödinger equation (MNLSE) for the simulation of nonlinear optical pulse propagation and gain saturation characteristics in the SOAs. In this MNLSE, the gain spectrum dynamics, gain saturation are taken into account those are depend on the carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. From this simulation, we obtained the output waveforms and spectra for different input pulse shapes considering different input energy levels. It has shown that the output pulse shape has changed due to the variation of input parameters, such as input pulse shape, input pulse width, and input pulse energy levels. It also shown clearly that the peak position of the output waveforms are shifted toward the leading edge which is due to the gain saturation of the SOA. We also compared the gain saturation characteristics in the SOA for different input pulse shapes.

  12. A high gain wide dynamic range transimpedance amplifier for optical receivers

    NASA Astrophysics Data System (ADS)

    Lianxi, Liu; Jiao, Zou; Yunfei, En; Shubin, Liu; Yue, Niu; Zhangming, Zhu; Yintang, Yang

    2014-01-01

    As the front-end preamplifiers in optical receivers, transimpedance amplifiers (TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range (DR) to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.

  13. Common base amplifier with 7 - dB gain at 176 GHz in InP mesa DHBT technology

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Paidi, V.; Griffith, Z.; Dahlstrom, M.; Wei, Y.; Urteaga, M.; Rodell, M. J. W.; Fung, A.

    2004-01-01

    We report a single stage tunded amplifier that exhibits 7 dB small signal gain at 176 GHz. Common Base topology is chosen as it has the best maximum stable gain (MSG) in this frequency band when compared to common emitter and common collector topologies. The amplifiers are designed and fabricated in InP mesa double heterojunction bipolar transistor (DHBT) technology.

  14. Common base amplifier with 7 - dB gain at 176 GHz in InP mesa DHBT technology

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Paidi, V.; Griffith, Z.; Dahlstrom, M.; Wei, Y.; Urteaga, M.; Rodell, M. J. W.; Fung, A.

    2004-01-01

    We report a single stage tunded amplifier that exhibits 7 dB small signal gain at 176 GHz. Common Base topology is chosen as it has the best maximum stable gain (MSG) in this frequency band when compared to common emitter and common collector topologies. The amplifiers are designed and fabricated in InP mesa double heterojunction bipolar transistor (DHBT) technology.

  15. Ultrafast laser inscription of a high-gain Er-doped bismuthate glass waveguide amplifier.

    PubMed

    Thomson, Robert R; Psaila, Nicholas D; Beecher, Stephen J; Kar, Ajoy K

    2010-06-07

    An Er-doped bismuthate glass waveguide amplifier has been fabricated using ultrafast laser inscription. Under zero pump conditions, the 87.0 mm long waveguide exhibited a fiber-to-fiber insertion loss of 4.0 dB at 1618 nm, outside the Er(3+) ion absorption band. We attribute approximately 1.8 dB of the insertion loss to coupling losses, 0.2 dB to Fresnel reflections and approximately 2.0 dB to propagation losses. When pumped using 1050 mW of 980 nm light, the amplifier exhibited a peak internal gain per unit length of 2.3 dB.cm(-1) at 1533 nm and a peak fiber-to-fiber net gain of 16.0 dB at 1533 nm. In this paper we also report the results of output power saturation and noise figure measurements.

  16. Fixed-gain CMOS differential amplifiers with no external feedback for a wide temperature range

    NASA Astrophysics Data System (ADS)

    Michal, Vratislav; Klisnick, Geoffroy; Sou, Gérard; Redon, Michel; Kreisler, Alain J.; Dégardin, Annick F.

    2009-11-01

    We present original CMOS amplifiers designed for the DC to 10 MHz frequency range and operating in the 70-380 K temperature range. Aimed applications concern readout circuitry to be associated with THz bolometric pixels (either high- Tc superconducting or uncooled semiconducting), which require accuracy, low noise and low power consumption. Two designs are described that both exhibit high fixed-gain (40 dB) in a feedback-free architecture, which is based on a new low-transconductance composite transistor for an accurate control of this gain. Both amplifiers have been realized in a regular 0.35 μm CMOS process and tested in the 4.2-380 K temperature range, exhibiting good agreement between designed and measured characteristics.

  17. Femtosecond Ti:sapphire cryogenic amplifier with high gain and MHz repetition rate.

    PubMed

    Dantan, Aurélien; Laurat, Julien; Ourjoumtsev, Alexei; Tualle-Brouri, Rosa; Grangier, Philippe

    2007-07-09

    We demonstrate high gain amplification of 160-femtosecond pulses in a compact double-pass cryogenic Ti:sapphire amplifier. The setup involves a negative GVD mirrors recompression stage, and operates with a repetition rate between 0.2 and 4 MHz with a continuous pump laser. Amplification factors as high as 17 and 320 nJ Fourier-limited pulses are obtained at a 800 kHz repetition rate.

  18. Investigations of SBS and Laser Gain Competition in High-Power Phase Modulated Fiber Amplifiers (Postprint)

    DTIC Science & Technology

    2014-02-26

    through radio frequency (RF) phase modulation. Generally, linewidth broadening is achieved through a filtered microwave white noise source (WNS). WNS...signals. By seeding with appropriate wavelengths and seed powers, the effective length of the amplifier is shortened as the narrow linewidth signal...line (phase modulated) 1064 nm seed in conjunction with a broadband 1036 nm seed source. 2. PHASE MODULATED LASER GAIN COMPETITION Recently, we have

  19. High-efficiency high-gain monolithic heterostructure FET amplifier at 31 GHz

    NASA Technical Reports Server (NTRS)

    Tserng, H. Q.; Saunier, P.; Kao, Y.-C.

    1993-01-01

    A three-stage heterostructure FET monolithic amplifier has achieved a power-added efficiency of 36 percent with 200 mW output and 18 dB gain at 31 GHz. At a higher drain voltage, the output power increases to 280 mW (with 17.5 dB gain and 31 percent PAE) at a power density of 0.7 W/mm. The MMIC chip measures 2.63 x 1.35 sq mm and requires only a single drain bias and a single gate bias.

  20. Erbium-doped spiral amplifiers with 20 dB of net gain on silicon.

    PubMed

    Vázquez-Córdova, Sergio A; Dijkstra, Meindert; Bernhardi, Edward H; Ay, Feridun; Wörhoff, Kerstin; Herek, Jennifer L; García-Blanco, Sonia M; Pollnau, Markus

    2014-10-20

    Spiral-waveguide amplifiers in erbium-doped aluminum oxide on a silicon wafer are fabricated and characterized. Spirals of several lengths and four different erbium concentrations are studied experimentally and theoretically. A maximum internal net gain of 20 dB in the small-signal-gain regime is measured at the peak emission wavelength of 1532 nm for two sample configurations with waveguide lengths of 12.9 cm and 24.4 cm and concentrations of 1.92 × 10(20) cm(-3) and 0.95 × 10(20) cm(-3), respectively. The noise figures of these samples are reported. Gain saturation as a result of increasing signal power and the temperature dependence of gain are studied.

  1. High Gain Submicrometer Optical Amplifier at Near-Infrared Communication Band.

    PubMed

    Wang, Xiaoxia; Zhuang, Xiujuan; Yang, Sen; Chen, Yu; Zhang, Qinglin; Zhu, Xiaoli; Zhou, Hong; Guo, Pengfei; Liang, Junwu; Huang, Yu; Pan, Anlian; Duan, Xiangfeng

    2015-07-10

    Nanoscale near-infrared optical amplification is important but remains a challenge to achieve. Here we report a unique design of silicon and erbium silicate core-shell nanowires for high gain submicrometer optical amplification in the near-infrared communication band. The high refraction index silicon core is used to tightly confine the optical field within the submicron structures, and the single crystalline erbium-ytterbium silicates shell is used as the highly efficient gain medium. Both theoretical and experimental results show that, by systematically tuning the core diameter and shell thickness, a large portion of the optical power can be selectively confined to the erbium silicate shell gain medium to enable a low loss waveguide and high gain optical amplifier. Experimental results further demonstrate that an optimized core-shell nanowire can exhibit an excellent net gain up to 31  dB mm(-1), which is more than 20 times larger than the previously reported best results on the micron-scale optical amplifiers.

  2. Gain Filtering for Single-Spatial-Mode Operation of Large-Mode-Area Fiber Amplifiers

    SciTech Connect

    Marciante, J.R.

    2009-02-06

    Gain filtering of higher order modes in large-mode-area fibers is an extremely robust method for providing diffraction-limited performance regardless of core diameter or input beam quality. Analytic calculations demonstrate that reducing the diameter of the gain dopants compared to the waveguide diameter produces differential gain that is higher for the fundamental mode than all other fiber modes at all saturation levels. Matching the gain dopant to the mode profile is not as beneficial as a simple step profile since the primarymechanism of gain filtering is to deny gain toward the edge of the waveguide where most of the higher order mode power is contained. Numerical simulations of multikilowatt fiber amplifiers with up to 100-μm-diameter cores show that gain filtering is extremely robust, providing 99% of the output power in the fundamental mode output with only 90% of the seed power in the fundamental mode. Even with poor seed launch with 50% of the power in the fundamental mode, gain filtering can provide up to 90% of the output power in the fundamental mode.

  3. Full-aperture gain measurement of diode-pumped Nd:YAG slab laser amplifier with intensity ratio method

    NASA Astrophysics Data System (ADS)

    Guo, Guangyan; Fan, Zhongwei; Chen, Yanzhong; Jia, Dan; Lin, Weiran; Qiu, Jisi; Kang, Zhijun; Zhao, Tianzhuo; He, Jianguo

    2017-09-01

    A full-aperture gain measurement obtained with the intensity ratio is presented for a diode-pumped ceramic slab laser amplifier. The small-signal gain profile of the amplifier is calculated by the ratio of pump-on and pump-off intensities. The distribution of absorbed pumping power, fluorescence distribution and gain in the width direction of the slab amplifier are simulated and measured, respectively. A gain homogeneity presented by standard deviation (σ) of 0.17 at a pump power of 1800 W is obtained in the experiment.

  4. Gain characteristics of LaF3:Er, Yb nanoparticle-doped waveguide amplifier.

    PubMed

    Li, Tong; Liu, Tianji; Chen, Cong; Zhang, Dan; Wang, Fei; Zhang, Daming

    2011-11-01

    Fundamental rate equations and power propagation equations were used to simulate the gain factors of LaF3:Er, Yb nanoparticle-doped waveguide amplifiers excited at 980 nm. The gain first increased and then remained nearly constant with pump power increasing. The gain and the threshold pump power increased with increasing concentration of Er3+. The calculated gain of the concentration 0.75 x 10(26) ions/m3 on a 4 cm long waveguide was 3.6 dB. An optimum waveguide length was found for the highest gain and it was getting larger with the increase of the pump power. When the lifetime decreases from the Judd-Ofelt calculated value of 13.34 ms to the measured value of 60 micros, the required pump power of a 0.5 dB gain increased one level. We obtained a longer 4I(13/2) lifetime (100 micros) through decreasing the proportions of Er3+ and Yb3+ in nanoparticles and found that the threshold pump power decreased more at the expenses of saturated gain.

  5. Graphene Distributed Amplifiers: Generating Desirable Gain for Graphene Field-Effect Transistors

    PubMed Central

    Lyu, Hongming; Lu, Qi; Huang, Yilin; Ma, Teng; Zhang, Jinyu; Wu, Xiaoming; Yu, Zhiping; Ren, Wencai; Cheng, Hui-Ming; Wu, Huaqiang; Qian, He

    2015-01-01

    Ever since its discovery, graphene bears great expectations in high frequency electronics due to its irreplaceably high carrier mobility. However, it has long been blamed for the weakness in generating gains, which seriously limits its pace of development. Distributed amplification, on the other hand, has successfully been used in conventional semiconductors to increase the amplifiers’ gain-bandwidth product. In this paper, distributed amplification is first applied to graphene. Transmission lines phase-synchronize paralleled graphene field-effect transistors (GFETs), combining the gain of each stage in an additive manner. Simulations were based on fabricated GFETs whose fT ranged from 8.5 GHz to 10.5 GHz and fmax from 12 GHz to 14 GHz. A simulated four-stage graphene distributed amplifier achieved up to 4 dB gain and 3.5 GHz bandwidth, which could be realized with future IC processes. A PCB level graphene distributed amplifier was fabricated as a proof of circuit concept. PMID:26634442

  6. A 55 μW programmable gain amplifier with constant bandwidth for a direct conversion receiver

    NASA Astrophysics Data System (ADS)

    Masuch, Jens; Delgado-Restituto, Manuel

    2011-05-01

    A fully differential programmable gain amplifier (PGA) with constant transfer characteristic and very low power consumption is proposed and implemented in a 130 nm CMOS technology. The PGA features a gain range of 4 dB to 55 dB with a step size of 6 dB and a constant bandwidth of 10-550 kHz. It employs two stages of variable amplification with an intermediate 2nd order low-pass channel filter. The first stage is a capacitive feedback OTA using current-reuse achieving a low input noise density of 16.7 nV/√Hz. This stage sets the overall high-pass cutoff frequency to approximately 10 kHz. For all gain settings the high-pass cutoff frequency variation is within +/-5%. The low-pass channel filter is merged with a second amplifying stage forming a Sallen-Key structure. In order to maintain a constant transfer characteristic versus gain, the Sallen-Key feedback is taken from different taps of the load resistance. Using this new approach, the low-pass cutoff frequency stays between 440 kHz and 590 kHz for all gain settings (+/-14%). Finally, an offset cancelation loop reduces the output offset of the PGA to less than 5 mV (3σ). The PGA occupies an area of approximately 0.06 mm2 and achieves a post-layout power consumption of 55 μW from a 1V-supply. For the maximum gain setting the integrated input referred noise is 14.4 μVRMS while the total harmonic distortion is 0.7 % for a differential output amplitude of 0.5 V.

  7. Measurements of the Low Frequency Gain Fluctuations of a 30 GHz High-Electron-Mobility-Transistor Cryogenic Amplifier

    NASA Technical Reports Server (NTRS)

    Jarosik, Norman

    1994-01-01

    Low frequency gain fluctuations of a 30 GHz cryogenic HEMT amplifier have been measured with the input of the amplifier connected to a 15 K load. Effects of fluctuations of other components of the test set-up were eliminated by use of a power-power correlation technique. Strong correlation between output power fluctuations of the amplifier and drain current fluctuations of the transistors comprising the amplifier are observed. The existence of these correlations introduces the possibility of regressing some of the excess noise from the HEMT amplifier's output using the measured drain currents.

  8. Gain recovery in a quantum dot semiconductor optical amplifier and corresponding pattern effects in amplified optical signals at 1.5 μm.

    PubMed

    Park, J; Jang, Y D; Baek, J S; Kim, N J; Yee, K J; Lee, H; Lee, D; Pyun, S H; Jeong, W G; Kim, J

    2012-03-12

    Fast gain recovery observed in quantum-dot semiconductor-optical-amplifiers (QDSOAs) is useful for amplifying high-speed optical signals. The small but finite slow recovery component can deteriorate the signal amplification due to the accumulation of gain saturation during 10 Gb/s operation. A study of the gain recoveries and pattern effects in signals amplified using a 1.5 μm InAs/InGaAsP QDSOA reveals that the gain recovery is always fast, and pattern-effect-free amplification is observed at the ground state. However, at the excited state, the slow component increases with the current, and significant pattern effects are observed. Simulations of the pattern effects agreed with the observed experimental trends.

  9. Maximization of net optical gain in silicon-waveguide Raman amplifiers.

    PubMed

    Rukhlenko, Ivan D; Dissanayake, Chethiya; Premaratne, Malin; Agrawal, Govind P

    2009-03-30

    We present a novel method for maximizing signal gain in continuously pumped silicon-waveguide Raman amplifiers made with silicon-on-insulator technology. Our method allows for pump-power depletion during Raman amplification and makes use of a variational technique. Its use leads to a system of four coupled nonlinear differential equations, whose numerical solution provides the optimal axial profile of the effective mode area along the waveguide length that maximizes the output signal power for a given amplifier length and a preset input (or output) cross-section area. In practice, the optimum profile can be realized by varying the cross-section area of a silicon waveguide along its length by tapering its width appropriately.

  10. SLUG Microwave Amplifier as a Nonreciprocal Gain Element for Scalable Qubit Readout

    NASA Astrophysics Data System (ADS)

    Thorbeck, Ted; Leonard, Edward; Zhu, Shaojiang; McDermott, Robert

    Josephson parametric amplifiers for superconducting qubits require several stages of cryogenic isolation to protect the qubit from strong microwave pump tones and downstream noise. But isolators and circulators are large, expensive and magnetic, so they are an obstacle to scaling up a superconducting quantum computer. In contrast, the SLUG (Superconducting Low-inductance Undulatory Galvanometer) is a high gain, broadband, low noise microwave amplifier that provides built-in reverse isolation. Here, we describe the dependence of the SLUG reverse isolation on signal frequency and device operating point. We show that the reverse isolation of the SLUG can be as large as or larger than that of a bulk commercial isolator. Finally, we discuss the use of the SLUG to read out a transmon qubit without isolators or circulators.

  11. An implantable neural activity monitor with nonlinear gain-controlled amplifier.

    PubMed

    Kyoso, Masaki; Takeda, Takahiro

    2013-01-01

    An implantable neural spike monitor with nonlinear amplifier was proposed for robust measurement against noise. In embedded electrophysiological signal processing systems, detection performance depends on signal to noise ratio (SNR), however, it is getting worth after implantation because of neoformation surrounding the electrodes and so on. We proposed a spike enhancer in this study. It has two remarkable function; automatic gain optimization with feedback loop and SNR improvement by nonlinear amplifier. In this report, the system performance was evaluated without feedback loop. A prototype circuit is prepared with small number of parts and tested on input-output characteristics. For the final evaluation, neural spike signal from somatosensory cortex of a rat was applied to the circuit. The test results show that system can expand SNR on neural spike signal from rat. It indicates that the spike enhancer can improve total performance of neural activity processing system.

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

    PubMed

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

    2015-06-01

    A cryogenic composite-thin-disk amplifier with amplified spontaneous emission (ASE) rejection is implemented that overcomes traditional laser system problems in high-energy pulsed laser drivers of high average power. A small signal gain of 8 dB was compared to a 1.5 dB gain for an uncapped thin-disk without ASE mitigation under identical pumping conditions. A strict image relayed 12-pass architecture using an off-axis vacuum telescope and polarization switching extracted 100 mJ at 250 Hz in high beam quality stretched 700 ps pulses of 0.6-nm bandwidth.

  13. A flat gain GaN MMIC power amplifier for X band application

    NASA Astrophysics Data System (ADS)

    Qin, Ge; Xinyu, Liu; Yingkui, Zheng; Chuan, Ye

    2014-12-01

    A flat gain two-stage MMIC power amplifier with a 2.8 GHz bandwidth is successfully developed for X band frequency application based on a fully integrated micro-strip AlGaN/GaN HEMT technology on a semi-insulating SiC substrate. Designed with a binary-cluster matching structure integrated with RC networks and LRC networks, the developed power MMIC gets a very flat small signal gain of 15 dB with a gain ripple of 0.35 dB over 9.1-11.9 GHz at the drain bias of 20 V. These RC networks are very easy to improve the stability of used GaN HEMTs with tolerance to the MMIC technology. Inside the frequency range of 9-11.2 GHz where the measurement system calibrated, the amplifier delivers a pulsed output power of 39 dBm and an associated power added efficiency of about 20% at 28 V without saturation, as the available RF power is limited.

  14. High Energy Double-Pulsed Ho:Tm:YLF Laser Amplifier

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Braud, Alain; Petros, Mulugeta; Singh, Upendra N.

    2002-01-01

    A high energy double-pulsed Ho:Tm:YLF 2-micrometer laser amplifier has been demonstrated. 600 mJ per pulse pair under Q-switch operation is achieved with the gain of 4.4. This solid-state laser source can be used as lidar transmitter for multiple lidar applications such as coherent wind and carbon dioxide measurements.

  15. Demonstration of a high-energy, narrow-bandwidth, and temporally shaped fiber regenerative amplifier.

    PubMed

    Qiao, Zhi; Wang, Xiaochao; Fan, Wei; Lin, Zunqi

    2015-09-15

    We report a high-energy and high-gain fiber regenerative amplifier for narrow-bandwidth nanosecond laser pulses that uses a Yb-doped photonic crystal fiber. The input pulse energy is 270 pJ for a 3.5 ns laser pulse with 0.3 nm (FWHM) bandwidth. At a pump laser power of 8.6 W at 974 nm, pulse energies up to 746 μJ with 1.2% (rms) energy stability are generated. To the best of our knowledge, this is the highest energy obtained in a fiber-based regenerative amplifier. A high-energy, nearly diffraction-limited, single-mode beam with a high gain of 64 dB shows promise for future application in the front ends of high-power laser facilities.

  16. Efficient use of hybrid Genetic Algorithms in the gain optimization of distributed Raman amplifiers.

    PubMed

    Neto, B; Teixeira, A L J; Wada, N; André, P S

    2007-12-24

    In this paper, we propose an efficient and accurate method that combines the Genetic Algorithm (GA) with the Nelder-Mead method in order to obtain the gain optimization of distributed Raman amplifiers. By using these two methods together, the advantages of both are combined: the convergence of the GA and the high accuracy of the Nelder-Mead. To enhance the convergence of the GA, several features were examined and correlated with fitting errors. It is also shown that when the right moment to switch between methods is chosen, the computation time can be reduced by a factor of two.

  17. Fast gain and phase recovery of semiconductor optical amplifiers based on submonolayer quantum dots

    SciTech Connect

    Herzog, Bastian Owschimikow, Nina; Kaptan, Yücel; Kolarczik, Mirco; Switaiski, Thomas; Woggon, Ulrike; Schulze, Jan-Hindrik; Rosales, Ricardo; Strittmatter, André; Bimberg, Dieter; Pohl, Udo W.

    2015-11-16

    Submonolayer quantum dots as active medium in opto-electronic devices promise to combine the high density of states of quantum wells with the fast recovery dynamics of self-assembled quantum dots. We investigate the gain and phase recovery dynamics of a semiconductor optical amplifier based on InAs submonolayer quantum dots in the regime of linear operation by one- and two-color heterodyne pump-probe spectroscopy. We find an as fast recovery dynamics as for quantum dot-in-a-well structures, reaching 2 ps at moderate injection currents. The effective quantum well embedding the submonolayer quantum dots acts as a fast and efficient carrier reservoir.

  18. Parasitic lasing suppression in high gain femtosecond petawatt Ti:sapphire amplifier.

    PubMed

    Liang, Xiaoyan; Leng, Yuxin; Wang, Cheng; Li, Chuang; Lin, Lihuang; Zhao, Baozhen; Jiang, Yunhua; Lu, Xiaoming; Hu, Minyuan; Zhang, Chunmei; Lu, Haihe; Yin, Dingjun; Jiang, Yongliang; Lu, Xingqiang; Wei, Hui; Zhu, Jianqiang; Li, Ruxin; Xu, Zhizhan

    2007-11-12

    New parasitic lasing suppression techniques are developed and high gain amplification is demonstrated in a petawatt level Ti:sapphire amplifier based on the chirped pulse amplification (CPA) scheme. Cladding the large aperture Ti:sapphire with refractive-index matched liquid doped with absorber suppresses the transverse lasing. The acousto-optic programmable dispersive filter (AOPDF) is used to realize side-lobe suppression in the temporal profile of the compressed pulse. The 800 nm laser output with peak power of 0.89 PW and pulse width of 29.0 fs is demonstrated.

  19. Design of a high-gain laser diode-array pumped Nd:YAG Alternating Precessive Slab Amplifier (APS-Amplifier)

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry

    1991-01-01

    In the design of space qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. A novel preamplifier design is examined which requires no external beam steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium.

  20. An S-band high gain relativistic klystron amplifier with high phase stability

    SciTech Connect

    Wu, Y.; Li, Z. H.; Xu, Z.; Ma, Q. S.; Xie, H. Q.

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  1. High-gain 35-GHz free-electron laser-amplifier experiment

    NASA Astrophysics Data System (ADS)

    Gold, S. H.; Hardesty, D. L.; Kinkead, A. K.; Barnett, L. R.; Granatstein, V. L.

    1984-04-01

    The efficient operation of a high-gain collective free-electron-laser (FEL) amplifier is demonstrated experimentally. The device investigated comprises a magnetron (20 kW, 500-nsec pulses at 35.02 GHz), a 20-dB-directivity input coupler for TE(11)-mode vertical polarization, the FEL interaction region (3-cm-period 63-cm-uniform-field-length wiggler field adjustable up to 4 kG, axial field up to 20 kG, and 10.08-mm drift tube), the VEBA pulse line accelerator (producing a 6-mm-diameter 900-keV 600-A 60-nsec FWHM relativistic electron beam), and a measurement setup. Linear growth at 1.2 dB/cm is reported, with total gain 50 dB, coherent emission 17 MW, and efficiency greater than 3 percent.

  2. Edge-pumped multi-slab amplifier for inertial fusion energy (IFE)

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhang, Xiaomin; Li, Mingzhong; Cui, Xudong; Wang, Zhenguo; Yan, Xiongwei; Jiang, Xinying; Zheng, Jiangang

    2016-11-01

    We proposed a novel laser amplifier for inertial fusion energy (IFE) based on an edge-pumped, gas-cooled multi-slab architecture. Compared to the face-pumped laser amplifiers for IFE, this architecture enables the pump, coolant and laser propagating orthogonally in the amplifier, thereby decoupling them in space and being beneficial to construction of the amplifier. To satisfy the high efficiency required for IFE, high-irradiance rectangle-waveguide coupled diode laser arrays are employed in the edge-pumped architecture and the pump light will be homogenized by total internal reflection. A traverse gradient doping profile is applied to the gain media, thus the pump absorption and gain uniformity can be separately optimized. Furthermore, the laser beam normal to the surfaces of the gas-cooled slabs will experience minimum thermal wavefront distortions in the amplifier head and ensure high beam quality. Since each slab has its own pump source and uniform gain in the aperture, power scaling can be easily achieved by placing identical slabs along the laser beam axis. Our investigations might provide an efficient and convenient way to design and optimize the amplifiers for IFE.

  3. Continuous-Time ΣΔ ADC with Implicit Variable Gain Amplifier for CMOS Image Sensor

    PubMed Central

    Bermak, Amine; Abbes, Amira; Amor Benammar, Mohieddine

    2014-01-01

    This paper presents a column-parallel continuous-time sigma delta (CTSD) ADC for mega-pixel resolution CMOS image sensor (CIS). The sigma delta modulator is implemented with a 2nd order resistor/capacitor-based loop filter. The first integrator uses a conventional operational transconductance amplifier (OTA), for the concern of a high power noise rejection. The second integrator is realized with a single-ended inverter-based amplifier, instead of a standard OTA. As a result, the power consumption is reduced, without sacrificing the noise performance. Moreover, the variable gain amplifier in the traditional column-parallel read-out circuit is merged into the front-end of the CTSD modulator. By programming the input resistance, the amplitude range of the input current can be tuned with 8 scales, which is equivalent to a traditional 2-bit preamplification function without consuming extra power and chip area. The test chip prototype is fabricated using 0.18 μm CMOS process and the measurement result shows an ADC power consumption lower than 63.5 μW under 1.4 V power supply and 50 MHz clock frequency. PMID:24772012

  4. Continuous-time ΣΔ ADC with implicit variable gain amplifier for CMOS image sensor.

    PubMed

    Tang, Fang; Bermak, Amine; Abbes, Amira; Benammar, Mohieddine Amor

    2014-01-01

    This paper presents a column-parallel continuous-time sigma delta (CTSD) ADC for mega-pixel resolution CMOS image sensor (CIS). The sigma delta modulator is implemented with a 2nd order resistor/capacitor-based loop filter. The first integrator uses a conventional operational transconductance amplifier (OTA), for the concern of a high power noise rejection. The second integrator is realized with a single-ended inverter-based amplifier, instead of a standard OTA. As a result, the power consumption is reduced, without sacrificing the noise performance. Moreover, the variable gain amplifier in the traditional column-parallel read-out circuit is merged into the front-end of the CTSD modulator. By programming the input resistance, the amplitude range of the input current can be tuned with 8 scales, which is equivalent to a traditional 2-bit preamplification function without consuming extra power and chip area. The test chip prototype is fabricated using 0.18 μm CMOS process and the measurement result shows an ADC power consumption lower than 63.5 μW under 1.4 V power supply and 50 MHz clock frequency.

  5. Theory and Simulation of Gain-Guided Noncollinear Modes in Chirped Quasi-Phase-Matched Optical Parametric Amplifiers

    SciTech Connect

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, Martin

    2009-09-01

    Chirped quasi-phase-matched (QPM) gratings offer essentially constant gain over wide bandwidths, making them promising candidates for short-pulse optical parametric amplifiers. However, experiments have shown that high-gain non-collinear processes exist in spite of the dephasing caused by the non-uniformity of the QPM grating and compete with the desired collinear broadband gain of the amplifier. In this paper, these non-collinear gain-guided modes are investigated numerically and analytically in a model that includes longitudinal non-uniformity of the phase-matching profile, lateral localization of the pump beam and non-collinear propagation of the interacting waves.

  6. Er3+-doped phosphate glasses with improved gain characteristics for broadband optical amplifiers

    NASA Astrophysics Data System (ADS)

    Amarnath Reddy, A.; Surendra Babu, S.; Vijaya Prakash, G.

    2012-11-01

    Optical properties of Erbium-doped sodium aluminum telluro-phosphate glasses with compositions of 48P2O5-21Na2O-23Al2O3-(8-x)TeO2-(x)Er2O3 (where x=2-7) were investigated. From the measured optical absorption spectra, Judd-Ofelt (JO) analysis has been carried out to predict radiative properties of doped Er3+ ion luminescent levels. The estimated emission cross sections were found to be more than other commonly available short-length optical amplifier (aluminosilicate) glasses. Relative emission intensity enhancement with the increase of Er3+ ion concentration is observed for the laser transition, 4I13/2→4I15/2 (at 1.53 μm). Higher emission lifetimes (4.2-6.23 ms), higher quantum efficiencies (44-65%) relative at higher Er3+ ion concentrations, high gain bandwidth and gain per unit length at 1.5 μm are the most notable features of these glasses for future optical amplifier applications.

  7. Dressed Gain from the Parametrically Amplified Four-Wave Mixing Process in an Atomic Vapor

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaoyang; Wen, Feng; Che, Junling; Zhang, Dan; Li, Changbiao; Zhang, Yanpeng; Xiao, Min

    2015-10-01

    With a forward cone emitting from the strong pump laser in a thermal rubidium atomic vapor, we investigate the non-degenerate parametrically amplified four-wave mixing (PA-FWM) process with dressing effects in a three-level “double-Λ” configuration both theoretically and experimentally. By seeding a weak probe field into the Stokes or anti-Stokes channel of the FWM, the gain processes are generated in the bright twin beams which are called conjugate and probe beams, respectively. However, the strong dressing effect of the pump beam will dramatically affect the gain factors both in the probe and conjugate channels, and can inevitably impose an influence on the quantum effects such as entangled degree and the quantum noise reduction between the two channels. We systematically investigate the intensity evolution of the dressed gain processes by manipulating the atomic density, the Rabi frequency and the frequency detuning. Such dressing effects are also visually evidenced by the observation of Autler-Townes splitting of the gain peaks. The investigation can contribute to the development of quantum information processing and quantum communications.

  8. Dressed Gain from the Parametrically Amplified Four-Wave Mixing Process in an Atomic Vapor

    PubMed Central

    Zhang, Zhaoyang; Wen, Feng; Che, Junling; Zhang, Dan; Li, Changbiao; Zhang, Yanpeng; Xiao, Min

    2015-01-01

    With a forward cone emitting from the strong pump laser in a thermal rubidium atomic vapor, we investigate the non-degenerate parametrically amplified four-wave mixing (PA-FWM) process with dressing effects in a three-level “double-Λ” configuration both theoretically and experimentally. By seeding a weak probe field into the Stokes or anti-Stokes channel of the FWM, the gain processes are generated in the bright twin beams which are called conjugate and probe beams, respectively. However, the strong dressing effect of the pump beam will dramatically affect the gain factors both in the probe and conjugate channels, and can inevitably impose an influence on the quantum effects such as entangled degree and the quantum noise reduction between the two channels. We systematically investigate the intensity evolution of the dressed gain processes by manipulating the atomic density, the Rabi frequency and the frequency detuning. Such dressing effects are also visually evidenced by the observation of Autler-Townes splitting of the gain peaks. The investigation can contribute to the development of quantum information processing and quantum communications. PMID:26463588

  9. Transverse amplified spontaneous emission: The limiting factor for output energy of ultra-high power lasers

    NASA Astrophysics Data System (ADS)

    Chvykov, Vladimir; Nees, John; Krushelnick, Karl

    2014-02-01

    For the new generation of the ultra-high power lasers with tens of PW of output power, kJ-level energies have to be reached. Our modeling, applied to Ti:sapphire amplifiers, demonstrates for the first time, according our knowledge, that Transverse Amplified Spontaneous Emission (TASE) places an additional restriction on storing and extracting energy in larger gain apertures, even stronger than transverse parasitic generation (TPG). Nevertheless, we demonstrate that extracting during pumping (EDP) can significantly reduce parasitic losses due to both TASE and TPG.

  10. 93-133 GHz Band InP High-Electron-Mobility Transistor Amplifier with Gain-Enhanced Topology

    NASA Astrophysics Data System (ADS)

    Sato, Masaru; Shiba, Shoichi; Matsumura, Hiroshi; Takahashi, Tsuyoshi; Nakasha, Yasuhiro; Suzuki, Toshihide; Hara, Naoki

    2013-04-01

    In this study, we developed a new type of high-frequency amplifier topology using 75-nm-gate-length InP-based high-electron-mobility transistors (InP HEMTs). To enhance the gain for a wide frequency range, a common-source common-gate hybrid amplifier topology was proposed. A transformer-based balun placed at the input of the amplifier generates differential signals, which are fed to the gate and source terminals of the transistor. The amplified signal is outputted at the drain node. The simulation results show that the hybrid topology exhibits a higher gain from 90 to 140 GHz than that of the conventional common-source or common-gate amplifier. The two-stage amplifier fabricated using the topology exhibits a small signal gain of 12 dB and a 3-dB bandwidth of 40 GHz (93-133 GHz), which is the largest bandwidth and the second highest gain reported among those of published 120-GHz-band amplifiers. In addition, the measured noise figure was 5 dB from 90 to 100 GHz.

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

    DOEpatents

    Hackel, Lloyd A [Livermore, CA; Soules, Thomas F [Livermore, CA; Fochs, Scott N [Livermore, CA; Rotter, Mark D [San Ramon, CA; Letts, Stephan A [San Ramon, CA

    2011-02-22

    A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.

  12. Optical amplifier exhibiting net phase-mismatch selected to at least partially reduce gain-induced phase-matching during operation and method of operation

    DOEpatents

    Feve, Jean-Philippe [Cupertino, CA; Kliner, Dahv A. V. [San Ramon, CA; Farrow,; Roger, L [Pleasanton, CA

    2011-02-01

    An optical amplifier, such as an optical waveguide amplifier (e.g., an optical fiber amplifier or a planar waveguide) or a non-guiding optical amplifier, that exhibits a net phase-mismatch selected to at least partially reduce gain-induced phase-matching during operation thereof is disclosed. In one aspect of the invention, an optical amplifier structure includes at least one optical amplifier having a length and a gain region. The at least one optical amplifier exhibits a net phase-mismatch that varies along at least part of the length thereof selected to at least partially reduce gain-induced phase-matching during operation thereof.

  13. High-gain, high-bandwidth, rail-to-rail, constant-gm CMOS operational amplifier

    NASA Astrophysics Data System (ADS)

    Huang, Hong-Yi; Wang, Bo-Ruei

    2013-01-01

    This study presents a high-gain, high-bandwidth, constant-gm , rail-to-rail operational amplifier (op-amp). The constant transconductance is improved with a source-to-bulk bias control of an input pair. A source degeneration scheme is also adapted to the output stage for receiving wide input range without degradation of the gain. Additionally, several compensation schemes are employed to enhance the stability. A test chip is fabricated in a 0.18 µm complementary metal-oxide semiconductor process. The active area of the op-amp is 181 × 173 µm2 and it consumes a power of 2.41 mW at a supply voltage of 1.8 V. The op-amp achieves a dc gain of 94.3 dB and a bandwidth of 45 MHz when the output capacitive load is connected to an effective load of 42.5 pF. A class-AB output stage combining a slew rate (SR) boost circuit provides a sinking current of 6 mA and an SR of 17 V/µs.

  14. Gain variation induced by power transient in thulium-doped fiber amplifier at 2 μm and its reduction by optical gain clamping technique

    NASA Astrophysics Data System (ADS)

    Khamis, M. A.; Ennser, K.

    2017-02-01

    This paper investigates the dynamic behavior of a thulium doped fiber amplifier (TDFA) operating in the 2 μm region for reconfigurable wavelength division multiplexing (WDM) systems. We show deleterious channel power fluctuations may be generated by input power variation at the amplifier and we propose the use of an optical gain-clamping technique. The investigated system consists of 20 channels with -4 dBm total input power. Our findings revealed that the effects of power transients due to channel reconfigurations are significantly reduced by a lasing feedback signal. Simulation results show that a power excursion of 4.3 dB is produced after dropping 19 channels when the amplifier gain is unclamped and only 0.0062 dB when the amplifier gain is clamped. The dynamics of GC-TDFA are mainly influenced by the value of the pump power factor and thus the laser signal achieves a stronger stabilization condition with increasing pump power factor. Hence, optical gain clamping is a simple and robust technique to control the power transient in the thulium-doped fiber amplifier of WDM systems at 2 μm.

  15. Spatial-temporal gain distribution of a CuBr vapor brightness amplifier

    NASA Astrophysics Data System (ADS)

    Gubarev, F. A.; Li, Lin; Klenovskii, M. S.; Shiyanov, D. V.

    2016-11-01

    The paper presents the results of study of the radial distribution of radiation inside the copper bromide vapor amplifiers depending on the time of return of their own reflected radiation. This technique allows us to estimate the changes of the gain profile during the lasing pulse. The profile distribution which is close to the Gaussian's one is as follows for the first 7-12 ns without the addition of HBr and up to 18 ns with HBr. By the end of the lasing pulse, the profile becomes ring-shaped. The results from this study indicate that the inversion in the center of the beam disappears earlier than at the periphery. This is equally true for both the green lasing line (510.6 nm) and the yellow one (578.2 nm). The radiation profile can be flattened partially by introducing the active HBr doping, but it does not provide a uniform profile throughout the lasing pulse.

  16. Suppression of higher mode excitation in a high gain relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xu, Z.; Jin, X.; Li, Z. H.; Tang, C. X.

    2012-02-01

    Suppressing higher mode excitation is very important in the high gain relativistic klystron amplifier because higher mode can seriously degrade klystron performance and cause pulse shortening. The mechanism of higher mode self-excitation is explored in the PIC simulation, and it is shown the coupling between cavities is the main cause of higher mode self-excitation. The coupling forms the positive feedback loop for higher mode to be excited just like that in the oscillator circuit. The formula for startup current of higher mode self-excitation is developed based on the coupling between cavities. And the corresponding methods are taken to avoid higher mode self-excitation. Finally, mode control is realized in the RKA with output power up to 1.02 GW when driven power is only few kilowatts.

  17. Unimolecular amplifier: principles of a three-terminal device with power gain

    NASA Astrophysics Data System (ADS)

    Toher, Cormac; Nozaki, Daijiro; Cuniberti, Gianaurelio; Metzger, Robert M.

    2013-07-01

    A single molecule composed of three linked moieties can function as an amplifier of electrical current, when certain conditions are met by the molecular orbitals of the three component parts. This device should exhibit power gain at appropriate voltages. In this work, we will explain a plausible mechanism by which this device should work, and present its operating characteristics. In particular, we find that a fundamental requirement for current amplification is to have the LUMO of the central moiety more strongly coupled to a control electrode than it is to the other orbitals in the molecule, while the HOMO of this moiety should be more strongly coupled to the orbitals in the other moieties than it is to the control electrode.A single molecule composed of three linked moieties can function as an amplifier of electrical current, when certain conditions are met by the molecular orbitals of the three component parts. This device should exhibit power gain at appropriate voltages. In this work, we will explain a plausible mechanism by which this device should work, and present its operating characteristics. In particular, we find that a fundamental requirement for current amplification is to have the LUMO of the central moiety more strongly coupled to a control electrode than it is to the other orbitals in the molecule, while the HOMO of this moiety should be more strongly coupled to the orbitals in the other moieties than it is to the control electrode. R. M. M. wishes to dedicate this paper to his research advisor, Prof. Harden Marsden McConnell, who celebrates his eighty-sixth birthday on 18 July 2013.

  18. Effects of undulator interruptions on the performance of high-gain FEL amplifiers

    SciTech Connect

    Kim, K.J.; Xie, M.; Pelligrini, C.

    1995-12-31

    The high-gain amplifiers for short wavelength free electron lasers (FELs) such as the LCLS project require a long undulator. The construction of the undulator as well as the FEL operation would become easier if the undulator could be interrupted with drift sections every few gain lengths. We have investigated the influence of such interruption on the FEL performances. Three effects are considered: (i) the diffraction loss, (ii) the phase mismatch and, (iii) the phase smearing due to velocity spread and to dispersion errors. The effect (i) is the loss during the process in which the optical mode in a section of the undulator leaves the undulator, propagates through the free space and then re-enters and re-adjusts in the next section. The effect (ii) is the fact that the phase of the optical beam is displaced with respect to the electrons density modulation for optical FEL interaction due to the slippage of the electron beam in the interruption region. The effect (iii) is the fact that electrons velocity spread, emittance, and dispersion due to misalignment of the quadrupoles used for additional focusing lead to a reduction of the bunching factor. We present an approximate analysis of these effects. When applied to the LCLS parameters, we find that the effect (i) is negligible, the effect (ii) gives a condition on the length of the drift section, and the effects (iii) are small, but could be non-negligible if there are sufficient number of interruptions.

  19. Pump scheme for gain-flattened Raman fiber amplifiers using improved particle swarm optimization and modified shooting algorithm.

    PubMed

    Jiang, Hai-ming; Xie, Kang; Wang, Ya-fei

    2010-05-24

    An effective pump scheme for the design of broadband and flat gain spectrum Raman fiber amplifiers is proposed. This novel approach uses a new shooting algorithm based on a modified Newton-Raphson method and a contraction factor to solve the two point boundary problems of Raman coupled equations more stably and efficiently. In combination with an improved particle swarm optimization method, which improves the efficiency and convergence rate by introducing a new parameter called velocity acceptability probability, this scheme optimizes the wavelengths and power levels for the pumps quickly and accurately. Several broadband Raman fiber amplifiers in C+L band with optimized pump parameters are designed. An amplifier of 4 pumps is designed to deliver an average on-off gain of 13.3 dB for a bandwidth of 80 nm, with about +/-0.5 dB in band maximum gain ripples.

  20. High-energy, ceramic-disk Yb:LuAG laser amplifier.

    PubMed

    Siebold, M; Loeser, M; Roeser, F; Seltmann, M; Harzendorf, G; Tsybin, I; Linke, S; Banerjee, S; Mason, P D; Phillips, P J; Ertel, K; Collier, J C; Schramm, U

    2012-09-24

    We report the first short-pulse amplification results to several hundred millijoule energies in ceramic Yb:LuAG. We have demonstrated ns-pulse output from a diode-pumped Yb:LuAG amplifier at a maximum energy of 580 mJ and a peak optical-to-optical efficiency of 28% at 550 mJ. In cavity dumped operation of a nanosecond oscillator we obtained 1 mJ at up to 100 Hz repetition rate. A gain bandwidth of 5.4 nm was achieved at room temperature by measuring the small-signal single-pass gain. Furthermore, we compared our results with Yb:YAG within the same amplifier system.

  1. The neutronics of an Accelerator-Driven Energy Amplifier

    SciTech Connect

    Moeller, E.; Gudowski, W.

    1995-10-01

    This study has been focused on an Accelerator-Driven Energy Amplifier, based on the concept proposed by the CERN-group. To analyze the performance of this system the extensive optimization of the core lattice was done, the temperature coefficients of reactivity were investigated, reactivity budget and power distribution were estimated.

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

    SciTech Connect

    Kim, K.J.

    1994-09-01

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

  3. Thermal modeling of gain competition in Yb-doped large-mode-area photonic-crystal fiber amplifier.

    PubMed

    Rosa, Lorenzo; Coscelli, Enrico; Poli, Federica; Cucinotta, Annamaria; Selleri, Stefano

    2015-07-13

    We propose a new model for gain competition effects in high-power fiber amplifiers, which accounts for the thermal effects of heat load on the doped core overlap of the propagating light field. The full-vectorial nature of the fiber modes is modeled by an embedded finite-element method modal solver, and the temperature profile is calculated by a simple and efficient radial heat propagation solver. The model is applied to a Yb³⁺-doped LPF45 air-clad photonic-crystal fiber amplifier for coand counter-propagating pumping setups, showing gain competition in conditions of severe heat load.

  4. Interaction of frequency-modulated light beams in multistage parametric amplifiers at the maximum gain bandwidth

    SciTech Connect

    Vlasov, Sergei N; Koposova, E V; Freidman, Gennadii I

    2009-05-31

    Conditions of the applicability of equations in the quasi-static approximation for studying the parametric interaction of frequency-modulated light beams in multistage amplifiers are considered. This approximation is used to simulate numerically processes in a multistage DKDP crystal amplifier with the output power exceeding 10 PW and suppressed luminescence. (lasers and amplifiers)

  5. Investigation of all-optical gain clamped erbium-doped amplifier in the presence of variable burst traffic

    NASA Astrophysics Data System (ADS)

    Zannin, M.; Mangeni, S.; Taccheo, S.; Ennser, K.; Barlet, P.; Careglio, D.

    2011-03-01

    Optical gain clamping is an all-optical method to control the gain of optical amplifiers. Recent results show that this technique is very robust and reduces impairments in amplification of typical traffic from optical burst (and packets) switching networks, where the traffic profile is very dynamic. Nevertheless, recent results have also shown that interplay between the characteristics of the optical gain clamping optical amplifier (OGC-OA) and particular traffic profiles may induce chaotic behavior caused by resonance in the OGC-OA lasing cavity. The aim of this investigation is to assess the impact of burst duration and inter-arrival time on these chaotic behavior cases. The investigation shows that the resonating frequency in which chaotic variation of the OGC-OA gain occurs is shifted - and even reduced - when the burst duration and inter-arrival time are changed. For this investigation, continuous trains of bursts were used, with fixed burst generation frequency throughout each case considered.

  6. Gain flattening filter in the DWDM systems using C-band or L-band optical amplifiers

    NASA Astrophysics Data System (ADS)

    Bibac, Ionut C.

    2003-10-01

    An optical transport network based on dense wavelength - division multiplexing DWDM technology is the next logical step in the evolution of Internet network. An Optical Internet network is defined as any Internet network where the network link layer connections are "dedicated" wavelengths on a Wave Division Multiplexed optical fibre directly connected to a high performance network router. The high performance network router replaces traditional ATM and SONET/SDH switching and multiplexing equipment, the essential statistical multiplexing device that controls wavelength access, switching, routing and protection. The optical amplifier is the key element that contributes to design an Optical Internet network. The design of an optical component and in particular an optical amplifier can directly and significantly affect the performance of an optical system. With the help of PTDS toll I will demonstrate the advantage of using L - band amplifiers especially for long - haul terrestrial or submarine DWDM systems in which thousands of amplifiers might be needed in a single transmission link. This is due to the exceptional feature that permits in a cascade configuration a very flat gain. It is demonstrated that L -band amplifier doesn"t require a gain-flattening fiber (GFF) compared to C -band amplifiers.

  7. Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

    SciTech Connect

    Kazlauskas, Karolis Kreiza, Gediminas; Bobrovas, Olegas; Adomėnienė, Ona; Adomėnas, Povilas; Juršėnas, Saulius; Jankauskas, Vygintas

    2015-07-27

    Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10{sup −2} cm{sup 2}/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 10{sup 9 }s{sup −1}) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm{sup 2}) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm{sup −1}) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.

  8. A novel design of ultra-broadband, high-gain and high-linearity variable gain distributed amplifier in 0.13 μm CMOS technology

    NASA Astrophysics Data System (ADS)

    Baharvand, Zainab; Hakimi, Ahmad; Rashedi, Esmat

    2016-12-01

    A high-gain, high-linearity and ultra-broadband variable gain distributed amplifier (VGDA) based on employing multiple techniques is presented to substantially increase the gain. The complete design is composed of two major parts including a VGDA part followed by a single stage distributed amplifier (SSDA) part. The VGDA part makes it possible to achieve different gain settings. For high gain considerations, the SSDA part cascades with the VGDA part that takes the benefits of the multiplicative gain mechanism. A theory is presented to enhance the linearity without imposing further DC power consumption. This idea has been validated by simulation results as expected. The design is analysed and simulated in the standard 0.13 μm CMOS technology. It presents the large gain tuning range of 35 dB, from -5 dB attenuation gain up to +30 dB maximum amplification gain, in relation to the control voltage (Vctr) that varies between 0.42 and 1.1 V. At the maximum amplification gain setting, it presents a DC up to 16 GHz 3 dB bandwidth, an average noise figure of 3.2 dB and an IIP3 of -2 dB m. Furthermore, it dissipates 46.42 mW from 0.7 and 0.9 V power supplies of the drain lines of VGDA and SSDA parts, respectively. Additionally, the Monte Carlo (MC) simulation has been performed to predict an estimate of the accuracy of performance of the proposed design under various conditions.

  9. Low noise gain-clamped L-band erbium-doped fiber amplifier by utilizing fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Wang, Tianshu; Guo, Yubin; Yan, Hongwei; Wang, Yuhang; Wang, Ke

    2006-11-01

    A novel gain-clamped long wavelength band (L-band) erbium-doped fiber amplifier (EDFA) is proposed and experimented by using a fiber Bragg grating (FBG) at the input end of the amplifier. This design provides a good gain clamping and decreases noise effectively. It uses two sections of erbium-doped fiber (EDF) pumped by a 1480-nm laser diode (LD) for higher efficiency and lower noise figure (NF). The gain is clamped at 23 dB with a variation of 0.5 dB from input signal power of -30 to -8 dBm for 1589 nm and NF below 5 dB is obtained. At the longer wavelength in L-band higher gain is also obtained and the gain is clamped at 16 dB for 1614 nm effectively. Because the FBG injects a portion of backward amplified spontaneous emission (ASE) back into the system, the gain enhances 5 dB with inputting small signal.

  10. Diode-pumped large-aperture Nd:YAG slab amplifier for high energy nanosecond pulse laser

    NASA Astrophysics Data System (ADS)

    Guo, Guangyan; Chen, Yanzhong; He, Jianguo; Lang, Ye; Lin, Weiran; Tang, Xiongxin; Zhang, Hongbo; Kang, Zhijun; Fan, Zhongwei

    2017-10-01

    A high gain, low thermal-induced wavefront distortion, laser diode-pumped Nd: YAG slab amplifier is demonstrated with its active media dimensions of 7 mm ×35 mm ×138.2 mm. Under the 200 Hz, 1440 W pulse pumping condition while no seed light to amplify, the thermal induced wavefront aberration of a He-Ne probe passing through the gain meUdium is 0.165 λ@633 nm (RMS). The amplifier shows stable aberration character with two major low-order terms, defocus and 0° astigmatism. The fluorescence distribution, stored energy, and small-signal gain of the amplifier are measured and have a good agreement with the calculated results. In the amplifier, the fluorescence is uniformly distributed and the maximum stored energy of 3.2 J can be achieved with a plane-concave cavity at 200 Hz pump repetition frequency. For a repetition frequency of 200 Hz, 25 μJ injection polarized seed-light and 1440 W pump power, the small signal gain reaches 9.45. The amplifier has been successfully employed in a 200 Hz, 5 J, MOPA system with 1.7 times diffraction limited output.

  11. Optical properties of the output of a high-gain, self-amplified free-electron laser.

    SciTech Connect

    Li, Y.; Lewellen, J.; Huang, Z.; Krinsky, S.; Accelerator Systems Division; BNL

    2004-01-01

    The temporal structure and phase evolutions of a high-gain, self-amplified free-electron laser are measured, including single-shot analysis and statistics over many shots. Excellent agreement with the theory of free-electron laser and photon statistics is found.

  12. An inductorless CMOS programmable-gain amplifier with a > 3 GHz bandwidth for 60 GHz wireless transceivers

    NASA Astrophysics Data System (ADS)

    Wei, Zhu; Baoyong, Chi; Lixue, Kuang; Wen, Jia; Zhihua, Wang

    2014-10-01

    An inductorless wideband programmable-gain amplifier (PGA) for 60 GHz wireless transceivers is presented. To attain wideband characteristics, a modified Cherry—Hooper amplifier with a negative capacitive neutralization technique is employed as the gain cell while a novel circuit technique for gain adjustment is adopted; this technique can be universally applicable in wideband PGA design and greatly simplifying the design of wideband PGA. By cascading two gain cells and an output buffer stage, the PGA achieves the highest gain of 30 dB with the bandwidth much wider than 3 GHz. The PGA has been integrated into one whole 60 GHz wireless transceiver and implemented in the TSMC 65 nm CMOS process. The measurements on the receiver front-end show that the receiver front-end achieves an 18 dB variable gain range with a > 3 GHz bandwidth, which proves the proposed PGA achieves an 18 dB variable gain range with a bandwidth much wider than 3 GHz. The PGA consumes 10.7 mW of power from a 1.2-V supply voltage with a core area of only 0.025 mm2.

  13. Laser amplifier chain

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

  14. Laser amplifier chain

    DOEpatents

    Hackel, R.P.

    1992-10-20

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

  15. Cold test, spontaneous emission and gain in a rectangular Cerenkov amplifier

    SciTech Connect

    Scharer, J.E.; Joe, J.; Booske, J.H.; Basten, M.; Kirolous, H.

    1994-12-31

    The authors present experimental results for the rectangular Cerenkov grating amplifier. This research is being carried out to develop a Ka-band (35 GHz), low voltage (10 kV), moderate power (10 kW) source. They have constructed a Ku-band grating structure to study a scaled version of this source. The tapered grating consists of two tapered Ku-band smooth wave guide sections and two 3.5-inch sections of five-step-tapered gratings. Both tapered and untapered grating structures have been cold tested utilizing the network analyzer measurements. They find that their taper design reduced the reflection coefficient from {minus}5 dB to less than {minus}20 dB over a 12--15 GHz bandwidth. Spontaneous emission results resulting from passing the circular electron beam from a Litton thermionic gun over the grating structure will be presented. They have theoretically investigated the sheet beam interaction with hybrid modes in a deep groove rectangular grating waveguide. A complex dispersion relation, which includes a finite axial energy spread of the beam, describing the interaction has been solved. The authors find that the instability is always convective in the forward wave mode regime.

  16. Energy efficient low-noise neural recording amplifier with enhanced noise efficiency factor.

    PubMed

    Majidzadeh, V; Schmid, A; Leblebici, Y

    2011-06-01

    This paper presents a neural recording amplifier array suitable for large-scale integration with multielectrode arrays in very low-power microelectronic cortical implants. The proposed amplifier is one of the most energy-efficient structures reported to date, which theoretically achieves an effective noise efficiency factor (NEF) smaller than the limit that can be achieved by any existing amplifier topology, which utilizes a differential pair input stage. The proposed architecture, which is referred to as a partial operational transconductance amplifier sharing architecture, results in a significant reduction of power dissipation as well as silicon area, in addition to the very low NEF. The effect of mismatch on crosstalk between channels and the tradeoff between noise and crosstalk are theoretically analyzed. Moreover, a mathematical model of the nonlinearity of the amplifier is derived, and its accuracy is confirmed by simulations and measurements. For an array of four neural amplifiers, measurement results show a midband gain of 39.4 dB and a -3-dB bandwidth ranging from 10 Hz to 7.2 kHz. The input-referred noise integrated from 10 Hz to 100 kHz is measured at 3.5 μVrms and the power consumption is 7.92 μW from a 1.8-V supply, which corresponds to NEF = 3.35. The worst-case crosstalk and common-mode rejection ratio within the desired bandwidth are - 43.5 dB and 70.1 dB, respectively, and the active silicon area of each amplifier is 256 μm × 256 μm in 0.18-μm complementary metal-oxide semiconductor technology.

  17. Effects of internal gain assumptions in building energy calculations

    NASA Astrophysics Data System (ADS)

    Christensen, C.; Perkins, R.

    The utilization of direct solar gains in buildings can be affected by operating profiles, such as schedules for internal gains, thermostat controls, and ventilation rates. Building energy analysis methods use various assumptions about these profiles. The effects of typical internal gain assumptions in energy calculations. Heating and cooling loads from simulations using the Department of Energy 2.1 computer code are compared for various internal-gain inputs: typical hourly profiles, constant average profiles, and zero gain profiles. Prototype single-family-detached and multi-family-attached residential units are studied with various levels of insulation and infiltration. Small detached commercial buildings and attached zones in large commercial buildings are studied with various levels of internal gains. The results indicate that calculations of annual heating and cooling loads are sensitive to internal gains, but in most cases are relatively insensitive to hourly variations in internal gains.

  18. If there is dissipation the particle can gain energy

    NASA Astrophysics Data System (ADS)

    Egydio de Carvalho, R.

    2015-10-01

    In this work, we summarize two different mechanisms to gain energy from the presence of dissipation in a time-dependent non-linear system. The particles can gain energy, in the average, from two different scenarios: i) for very week dissipation with the creation of an attractor with high velocity, and ii) in the opposite limit, for very strong dissipation, the particles can also gain energy from a boundary crisis. From the thermodynamic viewpoint both results are totally acceptable.

  19. Role of amplifiers gain on the achievable information rate of M-ary PSK and QAM constellations

    NASA Astrophysics Data System (ADS)

    Silva, Nuno A.; Pinto, Armando N.

    2017-01-01

    The impact of optical amplification on the achievable information rate (AIR) is evaluated, considering continuous and discrete modulation formats. The theoretical model for the AIR considers the optical amplification noise, the nonlinear optical noise, and the coherent receiver shot and thermal noise sources. Two different scenarios for the AIR are analyzed. First, we admit that the gain of each optical amplifier under or over compensate the previous fiber span loss. After that, we consider the case where we remove optical amplifiers from the transmission link. Results show that for the first scenario, when we under or over compensate the span loss the AIR tends to decrease. Nevertheless, for low cardinality constellations the AIR is not primarily limited by the gain of the optical amplifiers. In the second scenario, results show that it is possible to remove amplification stages from the end to the beginning of the transmission link without decreasing the AIR. We observe that for a polarization multiplexing (PM) 4-PSK constellation the plateau of 4 bits/symbol is preserved even if we remove the last two amplifiers from the transmission link.

  20. Amplified energy harvester from footsteps: design, modeling, and experimental analysis

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Chen, Wusi; Guzman, Plinio; Zuo, Lei

    2014-04-01

    This paper presents the design, modeling and experimental analysis of an amplified footstep energy harvester. With the unique design of amplified piezoelectric stack harvester the kinetic energy generated by footsteps can be effectively captured and converted into usable DC power that could potentially be used to power many electric devices, such as smart phones, sensors, monitoring cameras, etc. This doormat-like energy harvester can be used in crowded places such as train stations, malls, concerts, airport escalator/elevator/stairs entrances, or anywhere large group of people walk. The harvested energy provides an alternative renewable green power to replace power requirement from grids, which run on highly polluting and global-warming-inducing fossil fuels. In this paper, two modeling approaches are compared to calculate power output. The first method is derived from the single degree of freedom (SDOF) constitutive equations, and then a correction factor is applied onto the resulting electromechanically coupled equations of motion. The second approach is to derive the coupled equations of motion with Hamilton's principle and the constitutive equations, and then formulate it with the finite element method (FEM). Experimental testing results are presented to validate modeling approaches. Simulation results from both approaches agree very well with experimental results where percentage errors are 2.09% for FEM and 4.31% for SDOF.

  1. Gigahertz to terahertz tunable all-optical single-side-band microwave generation via semiconductor optical amplifier gain engineering.

    PubMed

    Li, Fangxin; Helmy, Amr S

    2013-11-15

    We propose and demonstrate a technique to generate low-noise broadly tunable single-side-band microwaves using cascaded semiconductor optical amplifiers (SOAs) using no RF bias. The proposed technique uses no RF components and is based on polarization-state controlled gain-induced four-wave mixing in SOAs. Microwave generation from 40 to 875 GHz with a line-width ~22 KHz is experimentally demonstrated.

  2. Experimental characteristics of a high-gain free-electron laser amplifier operating at 8-mm and 2-mm wavelengths

    SciTech Connect

    Throop, A.L.; Orzechowski, T.J.; Anderson, B.R.; Chambers, F.W.; Clark, J.C.; Fawley, W.M.; Jong, R.A.; Halbach, K.; Hopkins, D.B.; Sessler, A.M.

    1987-06-08

    The Electron Laser Facility (ELF) at the Lawrence Livermore National Laboratory (LLNL) uses a high-current induction linac (3.5 MeV, 1000 A), in conjunction with a pulsed electromagnetic wiggler (4.0 M, 4000 G), to operate a free electron laser (FEL) that produces intense radiation in the microwave regime (2 to 8 mm). ELF is a high-gain, single-pass amplifier, using a commercial microwave source as an oscillator input (200 W-50 kW). Previous experiments at 35 GHz produced exponential gains of 40 dB/m, peak powers exceeding 1 GW, and beam-to-rf conversion efficiencies of 34%. Recent experiments at 140 GHz have demonstrated exponential gains of 22 dB/m, peak powers exceeding 50 MW, and total gains of 65 dB. In this paper, we describe the experimental results at these two frequencies and compare then with the predictions of simulation codes.

  3. Wideband and flat-gain amplifier based on high concentration erbium-doped fibres in parallel double-pass configuration

    SciTech Connect

    Hamida, B A; Cheng, X S; Harun, S W; Naji, A W; Arof, H; Al-Khateeb, W; Khan, S; Ahmad, H

    2012-03-31

    A wideband and flat gain erbium-doped fibre amplifier (EDFA) is demonstrated using a hybrid gain medium of a zirconiabased erbium-doped fibre (Zr-EDF) and a high concentration erbium-doped fibre (EDF). The amplifier has two stages comprising a 2-m-long ZEDF and 9-m-long EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength region.

  4. Wideband and flat-gain amplifier based on high concentration erbium-doped fibres in parallel double-pass configuration

    NASA Astrophysics Data System (ADS)

    Hamida, B. A.; Cheng, X. S.; Harun, S. W.; Naji, A. W.; Arof, H.; Al-Khateeb, W.; Khan, S.; Ahmad, H.

    2012-03-01

    A wideband and flat gain erbium-doped fibre amplifier (EDFA) is demonstrated using a hybrid gain medium of a zirconiabased erbium-doped fibre (Zr-EDF) and a high concentration erbium-doped fibre (EDF). The amplifier has two stages comprising a 2-m-long ZEDF and 9-m-long EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength region.

  5. A Novel Erbium-Doped Fiber Amplifier Simulator for Gain Excursion Estimation in Multi-Channel Dynamic Optical Network

    NASA Astrophysics Data System (ADS)

    Roy, Sharbani; Priye, Vishnu

    2012-01-01

    A novel erbium-doped fiber amplifier simulator designed using the SIMULINK toolbox of MATLAB 7.0 (The MathWorks, Natick, MA, USA) is reported in this article. The present simulator has an ability to incorporate multi-channel amplification simultaneously in both the C- and L-bands. It is realized by defining new FUNCTION block sets and replacing the MATLAB FUNCTION block set reported earlier for multi-channel amplification. Spectral variation of gain for an erbium-doped fiber amplifier simulator is first verified in both the C- and L-bands. Next, the simulator is employed to study gain excursion in a multi-channel dynamic optical network, where the change in the gain excursion by varying the pump power has also been estimated. The present approach to estimate the gain excursion will find applications in quantifying inter-channel cross-talk due to cross-gain saturation among co-propagating multi-channels in a dynamic optical network.

  6. Terahertz Amplifier Based On Gain Switching In a Quantum Cascade Laser

    NASA Astrophysics Data System (ADS)

    Jukam, N.; Rungsawang, R.; Dhillon, S. S.; Oustinov, D.; Madéo, J.; Barbieri, S.; Manquest, C.; Sirtori, C.; Khanna, S. P.; Linfield, E.; Davies, A. G.; Tignon, J.

    2011-12-01

    A terahertz quantum cascade laser and an integrated Auston-switch are coupled to perform ultrafast gain switching. The resulting non-equilibrium gain is not clamped above laser threshold and large amplification of input terahertz pulses is demonstrated.

  7. Holmium YLF amplifier performance and the prospects for multi-Joule energies using diode-laser pumping

    NASA Technical Reports Server (NTRS)

    Storm, Mark E.

    1993-01-01

    Laser studies were performed to examine the amplifier characteristics of holmium-doped yttrium lithium fluoride (YLF) at 300 K. An inversion ratio of 0.37 was reached resulting in a measured small-signal gain coefficient of 0.50/cm. In a flashlamp pumping experiment, an output energy of 240 mJ was achieved for 38.5 mJ of input energy resulting in a large gain of 6.2. An amplifier model was developed for diode laser pumping and adapted to consider this flashlamp-pumped case. There is good agreement between the theory and experiment. Multipass amplifier calculations using the model suggest that the Ho: Tm: YLF laser crystal can support a 12 percent electrical to optical efficiency at 300 K even in the presence of upconversion.

  8. Holmium YLF amplifier performance and the prospects for multi-Joule energies using diode-laser pumping

    SciTech Connect

    Storm, M.E. )

    1993-02-01

    Laser studies were performed that examined the amplifier characteristics of holmium-doped yttrium lithium fluoride (YLF) at 300 K. An inversion ratio n[sup 5]I[sub 7]/n[sub H0] of 0.37 was reached resulting in a measured small-signal gain coefficient of 0.50 cm[sub [minus]1]. In a flashlamp pumping experiment, an output energy of 240 mJ was achieved for 38.5 Mj of input energy resulting in a large gain of 6.2. An amplifier model was developed for diode laser pumping and adapted to consider this flashlamp-pumped case. There is good agreement between the theory and experiment. Multipass amplifier calculations using the model suggest that the Ho:Tm:YLF laser crystal can support a 12% electrical to optical efficiency at 300 K even in the presence of upconversion.

  9. Pump-limited, 203 W, single-frequency monolithic fiber amplifier based on laser gain competition.

    PubMed

    Zeringue, Clint; Vergien, Christopher; Dajani, Iyad

    2011-03-01

    We present high power results of a Yb-doped fiber amplifier seeded with a combination of broad and single-frequency laser signals. This two-tone concept was used in conjunction with externally applied or intrinsically formed thermal gradients to demonstrate combined stimulated Brillouin scattering suppression in a copumped monolithic, polarization-maintaining (PM) fiber. Depending on the input parameters and the thermal gradient, the output power of the single-frequency signal ranged from 80 to 203 W with slope efficiencies from 70% to 80%. The 203 W amplifier was pump limited and is, to the best of our knowledge, the highest reported in the literature for monolithic, PM single-frequency fiber amplifiers.

  10. Effects of internal gain assumptions in building energy calculations

    NASA Astrophysics Data System (ADS)

    Christensen, C.; Perkins, R.

    1981-01-01

    The utilization of direct solar gains in buildings can be affected by operating profiles, such as schedules for internal gains, thermostat controls, and ventilation rates. Building energy analysis methods use various assumptions about these profiles. The effects of typical internal gain assumptions in energy calculations are described. Heating and cooling loads from simulations using the DOE 2.1 computer code are compared for various internal gain inputs: typical hourly profiles, constant average profiles, and zero gain profiles. Prototype single-family-detached and multifamily-attached residential units are studied with various levels of insulation and infiltration. Small detached commercial buildings and attached zones in large commercial buildings are studied with various levels of internal gains. The results indicate that calculations of annual heating and cooling loads are sensitive to internal gains, but in most cases are relatively insensitive to hourly variations in internal gains.

  11. Effects of internal gain assumptions in building energy calculations

    SciTech Connect

    Christensen, C.; Perkins, R.

    1981-01-01

    The utilization of direct solar gains in buildings can be affected by operating profiles, such as schedules for internal gains, thermostat controls, and ventilation rates. Building energy analysis methods use various assumptions about these profiles. The effects of typical internal gain assumptions in energy calculations are described. Heating and cooling loads from simulations using the DOE 2.1 computer code are compared for various internal-gain inputs: typical hourly profiles, constant average profiles, and zero gain profiles. Prototype single-family-detached and multi-family-attached residential units are studied with various levels of insulation and infiltration. Small detached commercial buildings and attached zones in large commercial buildings are studied with various levels of internal gains. The results of this study indicate that calculations of annual heating and cooling loads are sensitive to internal gains, but in most cases are relatively insensitive to hourly variations in internal gains.

  12. Use solar energy for remote antenna gain measurements

    SciTech Connect

    Doty, A.

    1988-06-01

    A new method for solar antenna gain measurements is proposed which is independent of the effective input system temperature. The method is based on the difference between two power measurements, the Dp factor, and requires little equipment. A spectrum analyzer that has an average noise-measurement mode calibrated in power/bandwidth (dBm/Hz) is connected to the output of a radar receiver's front-end low-noise amplifier (LNA), where it detects the system's noise levels. No other equipment is required, assuming that the RF loss between the LNA and the antenna terminal and the gain of the LNA are known. An example of calculations is given.

  13. Amplifying and compressing optical filter based on one-dimensional ternary photonic crystal structure containing gain medium

    NASA Astrophysics Data System (ADS)

    Jamshidi-Ghaleh, Kazem; Ebrahimpour, Zeinab; Moslemi, Fatemeh

    2015-07-01

    The transmission spectrum properties of the one-dimensional ternary photonic crystal (1DTPC) structure, composed of dielectric (D), metal (M) and gain (G) materials, with three different arrangements of (DGM)N, (GDM)N and (DMG)N, where N is the number of periodicity, were investigated. Two full photonic band gaps and N-1 resonant peaks, localized between them, were observed on transmittance spectra on near-UV spectrum region. When the gained layer was placed in front of the metal, the peaks appeared with higher resolution. There is a peak, localized on the higher band-edge of the first gap, which shows very interesting property than the other peaks. Thus, it amplifies and compresses faster with increase in the N and strength of the gain coefficient. The effects of the gain coefficient and periodicity number are graphically illustrated. This communication presents a PC structure that can be a good candidate to design an amplifying and compressing single or multi-channel optical filter in the UV region.

  14. Polarization beam combination technique for gain saturation effect compensation in high-energy systems

    NASA Astrophysics Data System (ADS)

    Chen, Junchi; Peng, Yujie; Su, Hongpeng; Leng, Yuxin

    2016-06-01

    To compensate for the gain saturation effect in the high-energy laser amplifier, a modified polarization beam combination (PBC) method is introduced to reshape temporal waveform of the injected laser pulse to obtain a controlled high-energy laser pulse shape after amplification. One linearly polarized beam is divided into two orthogonal polarized beams, which spatially recombine together collinearly after propagating different optical paths with relative time delay in PBC structure. The obtained beam with polarization direction being rotated by the following half wave plate is divided and combined again to reform a new beam in another modified polarization beam structure. The reformed beam is injected into three cascaded laser amplifiers. The amplified pulse shape can be controlled by the incident pulse shape and amplifier gain, which is agreeable to the simulation by the Frank-Nodvik equations. Based on the simple method, the various temporal waveform of output pulse with tunable 7 to 20 ns pulse duration can be obtained without interferometric fringes.

  15. 2.4 GHz CMOS Power Amplifier with Mode-Locking Structure to Enhance Gain

    PubMed Central

    2014-01-01

    We propose a mode-locking method optimized for the cascode structure of an RF CMOS power amplifier. To maximize the advantage of the typical mode-locking method in the cascode structure, the input of the cross-coupled transistor is modified from that of a typical mode-locking structure. To prove the feasibility of the proposed structure, we designed a 2.4 GHz CMOS power amplifier with a 0.18 μm RFCMOS process for polar transmitter applications. The measured power added efficiency is 34.9%, while the saturated output power is 23.32 dBm. The designed chip size is 1.4 × 0.6 mm2. PMID:25045755

  16. Hysteretic Flux Response and Nondegenerate Gain of Flux-Driven Josephson Parametric Amplifiers

    NASA Astrophysics Data System (ADS)

    Pogorzalek, Stefan; Fedorov, Kirill G.; Zhong, Ling; Goetz, Jan; Wulschner, Friedrich; Fischer, Michael; Eder, Peter; Xie, Edwar; Inomata, Kunihiro; Yamamoto, Tsuyoshi; Nakamura, Yasunobu; Marx, Achim; Deppe, Frank; Gross, Rudolf

    2017-08-01

    Josephson parametric amplifiers (JPAs) have become key devices in quantum science and technology with superconducting circuits. In particular, they can be utilized as quantum-limited amplifiers or as a source of squeezed microwave fields. Here, we report on the detailed measurements of five flux-driven JPAs exhibiting a hysteretic dependence of the resonant frequency on the applied magnetic flux. We model the measured characteristics by numerical simulations based on the two-dimensional potential landscape of the dc superconducting quantum interference devices, which provide the JPA nonlinearity for a nonzero screening parameter βL>0 and demonstrate excellent agreement between the numerical results and the experimental data. Furthermore, we study the nondegenerate response of different JPAs and accurately describe the experimental results with our theory.

  17. Active pulse shaping for end-pumped Nd:YVO4 amplifier with high gain.

    PubMed

    Nie, Mingming; Liu, Qiang; Ji, Encai; Cao, Xuezhe; Fu, Xing; Gong, Mali

    2017-03-15

    We demonstrated the active shaping for a solid-state Nd:YVO4 amplifier with a high average gain of 39.2 dB. The average output power was 8.3 W with respect to the input power of 1 mW. A range of common and useful pulse shapes was generated at the final output. In addition, a very flat square pulse was produced with a root-mean-square less than 3% in amplitude. A numerical method was proposed to realize active shaping without an experimental test for the Nd:YVO4 amplifier, showing great potential for the design of lasers with both high peak power (>100  kW) and a desired pulse shape.

  18. Gain enhanced L-band optical fiber amplifiers and tunable fiber lasers with erbium-doped fibers

    NASA Astrophysics Data System (ADS)

    Chen, H.; Leblanc, M.; Schinn, G. W.

    2003-02-01

    We report on the experimental investigation of gain enhanced L-band erbium-doped fiber amplifiers (EDFA) by either recycling residual ASE or using a second C-band wavelength pump laser and on the experimental demonstration of L-band tunable erbium-doped fiber ring lasers. We observed that by reflecting ASE from pumped erbium-doped fiber (EDF) the L-band EDFA gain can be enhanced of 2-15 dB depending on amplifier designs. We also studied wavelength and power dependence of second pump laser on the gain enhanced L-band EDFA and found that an optimum wavelength for second pump laser was between 1550 and 1560 nm. Finally, a L-band tunable erbium-doped fiber laser was also constructed in which lazing oscillation was observed closed to 1624 nm by recycling residual ASE. This L-band tunable laser has a line-width of about 300 MHz, an output power of 1 mW, and a signal to source spontaneous emission ratio of 60 dB.

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

    DOEpatents

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

    2008-12-09

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

  20. Compact, high-pulse-energy, high-power, picosecond master oscillator power amplifier.

    PubMed

    Chan, Ho-Yin; Alam, Shaif-Ul; Xu, Lin; Bateman, James; Richardson, David J; Shepherd, David P

    2014-09-08

    We report a compact, stable, gain-switched-diode-seeded master oscillator power amplifier (MOPA), employing direct amplification via conventional Yb(3+)-doped fibers, to generate picosecond pulses with energy of 17.7 μJ and 97-W average output power (excluding amplified spontaneous emission) at 5.47-MHz repetition frequency in a diffraction-limited and single-polarization beam. A maximum peak power of 197 kW is demonstrated. Such a high-energy, high-power, MHz, picosecond MOPA is of great interest for high-throughput material processing. With 13.8-μJ pulse energy confined in the 0.87-nm 3-dB spectral bandwidth, this MOPA is also a promising source for nonlinear frequency conversion to generate high-energy pulses in other spectral regions. We have explored the pulse energy scaling until the stimulated Raman Scattering (SRS) becomes significant (i.e. spectral peak intensity exceeds 1% of that of the signal).

  1. Optimization of the alignment sensitivity and energy stability of the NIF regenerative amplifier cavity/011

    SciTech Connect

    Hopps, N. W., Atomic Weapons Research Establishment, Aldermaston, Great Britain

    1998-06-24

    The work to improve the energy stability of the regenerative amplifier (`regen`) for the National Ignition Facility is described. This includes a fast feed-forward system, designed to regulate the output energy of the regen by monitoring how quickly a pulse builds up over many round trips. Shot-to-shot energy fluctuations of all elements prior to (and including) the regen may be compensated for in this way, at the expense of a loss of approximately 50%. Also included is a detailed study into the alignment sensitivity of the regen cavity, with the goal of quantifying the effect of misalignment on the output energy. This is done by calculating the displacement of the eigenmode by augmenting the cavity ABCD matrix with the misalignment matrix elements, E, F. In this way, cavity misalignment issues due to thermal loading of the gain medium are investigated. Alternative cavity designs, which reduce the alignment sensitivity and therefore the energy drift over periods of continuous operation, are considered. Alterations to the amplifier head design are also considered.

  2. Temperature-dependent absorption and gain of ytterbium-doped potassium double tungstates for chip-scale amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Yong, Yean-Sheng; Aravazhi, Shanmugam; Vázquez-Córdova, Sergio A.; Herek, Jennifer L.; García-Blanco, Sonia M.; Pollnau, Markus

    2017-02-01

    Ytterbium-doped potassium rare-earth double tungstate thin films are excellent candidates for highly efficient waveguide lasers, as well as high-gain waveguide amplifiers, with a record-high optical gain per unit length of 935 dB/cm recently demonstrated. However, the spectroscopic properties of these highly ytterbium-doped thin films and, in particular, their temperature dependence are not well investigated. These characteristics are required for the understanding of the behavior of the fabricated optical devices and crucial for further device optimization. We experimentally determined the absorption cross-sections for a potassium ytterbium gadolinium double tungstate, KYb0.57Gd0.43(WO4)2, thin film grown lattice matched onto an undoped KY(WO4)2 substrate. At room temperature, the peak cross-section value at 981 nm and the overall absorption spectrum are very similar to those of Yb-doped bulk potassium double tungstate crystals, although Yb is now the dominating rare-earth content. The temperature-dependent study shows a significant decrease of the absorption cross-section values at 933 nm and 981 nm with increasing temperature. We verify theoretically that this is due to the temperature dependence of fractional populations in the individual Stark levels of the absorbing crystal-field multiplet, in combination with the linewidth broadening with increasing temperature. Further investigations suggest that the broadening of absorption linewidth at 981 nm originates in the intra-manifold relaxation between the two lowest Stark levels of the ground state. Finally, the implications of the spectroscopic findings on the operating characteristics of waveguide amplifiers are investigated. Amplifiers operating at 80 °C are expected to exhibit only 67% of the maximum theoretical gain at room temperature.

  3. An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions

    NASA Astrophysics Data System (ADS)

    Lockerbie, N. A.; Tokmakov, K. V.

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m-1 was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain ratio

  4. An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions.

    PubMed

    Lockerbie, N A; Tokmakov, K V

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m(-1) was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain

  5. Double-passed, high-energy quasi-phase-matched optical parametric chirped-pulse amplifier

    SciTech Connect

    Jovanovic, I; Forget, N; Brown, C G; Ebbers, C A; Blanc, C L; Barty, C J

    2005-09-19

    Quasi-phase-matched (QPM) optical parametric chirped-pulse amplification (OPCPA) in periodically poled materials such as periodically poled LiNbO{sub 3} (PPLN) and periodically poled KTiOPO{sub 4} (PPKTP) has been shown to exhibit advantages over the OPCPA in bulk nonlinear crystals. [GHH98, RPN02] The use of the maximum material nonlinear coefficient results in ultra-high gain with low pump peak power. Furthermore, propagation of signal, pump, and idler beams along one of the crystal principal axes eliminates the birefringent walk-off, reduces angular sensitivity, and improves beam quality. Relatively high level of parasitic parametric fluorescence (PF) in QPM OPCPA represents an impediment for simple, single-stage, high-gain amplification of optical pulses from nJ to mJ energies. PF in QPM is increased when compared to PF in critical phase matching in bulk crystals as a result of broader angular acceptance of the nonlinear conversion process. PF reduces prepulse contrast and conversion efficiency by competition with the signal pulse for pump pulse energy. Previous experiments with QPM OPCPA have thus resulted in pulse energies limited to tens of {mu}J. [JSE03] Optical parametric amplification of a narrowband signal pulse in PPKTP utilizing two pump beams has been demonstrated at a mJ-level, [FPK03] but the conversion efficiency has been limited by low energy extraction of pump pulse in the first pass of amplification. Additionally, narrow spectral bandwidth was the result of operation far from signal-idler degeneracy. Here we present a novel double-pass, broad-bandwidth QPM OPCPA. 1.2 mJ of amplified signal energy is produced in a single PPKTP crystal utilizing a single 24-mJ pump pulse from a commercial pump laser. [JFE05] To our knowledge, this is the highest energy demonstrated in QPM OPCPA. Double-passed QPM OPCPA exhibits high gain (> 3 x 10{sup 6}), high prepulse contrast (> 3 x 10{sup 7}), high energy stability (3% rms), and excellent beam quality. We

  6. 18 CFR 11.13 - Energy gains calculations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Energy gains calculations. 11.13 Section 11.13 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  7. 18 CFR 11.13 - Energy gains calculations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Energy gains calculations. 11.13 Section 11.13 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  8. 18 CFR 11.13 - Energy gains calculations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Energy gains calculations. 11.13 Section 11.13 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  9. 18 CFR 11.13 - Energy gains calculations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Energy gains calculations. 11.13 Section 11.13 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  10. 18 CFR 11.13 - Energy gains calculations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Energy gains calculations. 11.13 Section 11.13 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  11. Influence of optical pumping wavelength on the ultrafast gain and phase recovery acceleration of quantum-dot semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Kim, Jungho

    2013-10-01

    We numerically investigate the influence of the optical pumping wavelength on the ultrafast gain and phase recovery acceleration of quantum-dot (QD) semiconductor optical amplifiers (SOAs) by solving 1088 coupled rate equations. The temporal variations of the gain and phase recovery response at the ground state (GS) of QDs are calculated at various signal wavelengths when the optical pumping wavelengths at the excited state (ES) of QDs are varied. The phase recovery response is fastest when the wavelength of the signal and pumping beams corresponds to the respective emission wavelength of the GS and the ES in the same size of QDs. The absorption efficiency of the optical pumping beam at the ES is determined by the Lorentzian line shape function of the homogeneous broadening.

  12. Study of Gain in C-Band Deflection Cavities for a Frequency-Doubling Magnicon Amplifier

    DTIC Science & Technology

    1993-03-26

    surface cleanliness , and background vacuum pressure. The threshold for multipactor in the drive cavity, in the presence of the axial magnetic field, was...different degrees of surface cleanliness . In order to make an unambiguous test of the linear interaction theory, the experimental gain measurements were

  13. Gm-Realization of Controlled-Gain Current Follower Transconductance Amplifier

    PubMed Central

    Tangsrirat, Worapong

    2013-01-01

    This paper describes the conception of the current follower transconductance amplifier (CFTA) with electronically and linearly current tunable. The newly modified element is realized based on the use of transconductance cells (G m s) as core circuits. The advantage of this element is that the current transfer ratios (i z/i p and i x/i z) can be tuned electronically and linearly by adjusting external DC bias currents. The circuit is designed and analyzed in 0.35 μm TSMC CMOS technology. Simulation results for the circuit with ±1.25 V supply voltages show that it consumes only 0.43 mw quiescent power with 70 MHz bandwidth. As an application example, a current-mode KHN biquad filter is designed and simulated. PMID:24381513

  14. 100 kW peak power picosecond thulium-doped fiber amplifier system seeded by a gain-switched diode laser at 2 μm.

    PubMed

    Heidt, A M; Li, Z; Sahu, J; Shardlow, P C; Becker, M; Rothhardt, M; Ibsen, M; Phelan, R; Kelly, B; Alam, S U; Richardson, D J

    2013-05-15

    We report on the generation of picosecond pulses at 2 μm directly from a gain-switched discrete-mode diode laser and their amplification in a multistage thulium-doped fiber amplifier chain. The system is capable of operating at repetition rates in the range of 2 MHz-1.5 GHz without change of configuration, delivering high-quality 33 ps pulses with up to 3.5 μJ energy and 100 kW peak power, as well as up to 18 W of average power. These results represent a major technological advance and a 1 order of magnitude increase in peak power and pulse energy compared to existing picosecond sources at 2 μm.

  15. Femtosecond laser written 16.5 mm long glass-waveguide amplifier and laser with 5.2 dB cm-1 internal gain at 1534 nm

    NASA Astrophysics Data System (ADS)

    Hoyo, J.; Berdejo, V.; Toney Fernandez, T.; Ferrer, A.; Ruiz, A.; Valles, J. A.; Rebolledo, M. A.; Ortega-Feliu, I.; Solis, J.

    2013-10-01

    A 16.5 mm long, heavily doped erbium-ytterbium phosphate glass-waveguide amplifier was fabricated by the femtosecond laser (fs-laser) inscription technique. The femtosecond laser inscription of waveguides was carried out at 500 kHz repetition rate using a 0.68 NA aspheric lens. The energy deposition profile in the dielectric material was initially simulated using a generalized adaptive fast-Fourier evolver (GAFFE) algorithm. The size and shape of the guiding structures were carefully controlled by the slit shaping technique to reduce the coupling losses, with achievable values down to less than 0.1 dB. Rigorous simulations of the response of the active waveguides were carried out to optimize their performance as optical amplifiers. A maximum of 8.6 dB internal gain at 1534 nm was obtained upon bidirectional laser pumping at 976 nm, leading to a gain per unit length of 5.2 dB cm-1. Laser action was also achieved for both ring and linear cavity configurations.

  16. A multifunctional switched-capacitor programmable gain amplifier for high-definition video analog front-ends

    NASA Astrophysics Data System (ADS)

    Hong, Zhang; Jie, Zhang; Mudan, Zhang; Xue, Li; Jun, Cheng

    2015-03-01

    A multifunctional programmable gain amplifier (PGA) that provides gain and offset adjusting abilities for high-definition video analog front-ends (AFE) is presented. With a switched-capacitor structure, the PGA also acts as a sample and holder of the analog-to-digital converter (ADC) in the AFE to reduce the power consumption and chip area of the whole AFE. Furthermore, the PGA converts the single-ended video signal into differential signal for the following ADC to reject common-mode noise and interferences. The 9-bit digital-to-analog converter (DAC) for gain and offset adjusting is embedded into the switched capacitor networks of the PGA. A video AFE integrated circuit based on the proposed PGA is fabricated in a 0.18-μm process. Simulation and measurement results show that the PGA achieves a gain control range of 0.90 to 2.34 and an offset control range of -220 to 220 mV while consuming 10.1 mA from a 1.8 V power supply. Project supported by the National Natural Science Foundation of China (No. 61106027), and the Science and Technology Project of Shanxi Province (No. 2014K05-14).

  17. Gain and noise characteristics of high-bit-rate silicon parametric amplifiers.

    PubMed

    Sang, Xinzhu; Boyraz, Ozdal

    2008-08-18

    We report a numerical investigation on parametric amplification of high-bit-rate signals and related noise figure inside silicon waveguides in the presence of two-photon absorption (TPA), TPA-induced free-carrier absorption, free-carrier-induced dispersion and linear loss. Different pump parameters are considered to achieve net gain and low noise figure. We show that the net gain can only be achieved in the anomalous dispersion regime at the high-repetition-rate, if short pulses are used. An evaluation of noise properties of parametric amplification in silicon waveguides is presented. By choosing pulsed pump in suitably designed silicon waveguides, parametric amplification can be a chip-scale solution in the high-speed optical communication and optical signal processing systems.

  18. A simple method to increase effective PMT gain by amplifier circuit powered from voltage divider

    SciTech Connect

    Popov, V.; Majewski, S.; Wojtsekhowski, B.; Guerin, D

    2001-11-01

    A novel concept is introduced of additional effective signal amplification by employing a dedicated circuit to process anode or dynode signals prior to sending them through a standard 50 /spl Omega/ line/cable. The circuit is entirely powered by the current flowing through the base voltage divider. Additional gain factors of 2-10 were easily achieved with preserved operation speed and rate capability up to several MHz. This additional signal boost can be used in many applications where higher gain and/or lower PMT operational voltages are desirable. For example, in the case of a PMT employed in a low input light signal (such as a Cherenkov counter), this technique will permit operation at a lower voltage and, therefore, will result in better operational PMT stability and longer PMT lifetime. At present, two experimental set-ups at Jefferson Lab are using PMT bases using this concept.

  19. Effects of bandwidth, compression speed, and gain at high frequencies on preferences for amplified music.

    PubMed

    Moore, Brian C J

    2012-09-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening via a simulated five-channel compression hearing aid with gains set using the CAM2 fitting method, preferences for upper cutoff frequency varied across participants: Some preferred a 7.5- or 10-kHz upper cutoff frequency over a 5-kHz cutoff frequency, and some showed the opposite preference. Preferences for a higher upper cutoff frequency were associated with a shallow high-frequency slope of the audiogram. A subsequent study comparing the CAM2 and NAL-NL2 fitting methods, with gains slightly reduced for participants who were not experienced hearing aid users, showed a consistent preference for CAM2. Since the two methods differ mainly in the gain applied for frequencies above 4 kHz (CAM2 recommending higher gain than NAL-NL2), these results suggest that extending the upper cutoff frequency is beneficial. A system for reducing "overshoot" effects produced by compression gave small but significant benefits for sound quality of a percussion instrument (xylophone). For a high-input level (80 dB SPL), slow compression was preferred over fast compression.

  20. Energy harvesting through a backpack employing a mechanically amplified piezoelectric stack

    NASA Astrophysics Data System (ADS)

    Feenstra, Joel; Granstrom, Jon; Sodano, Henry

    2008-04-01

    Over the past few decades, the use of portable and wearable electronics has grown steadily. These devices are becoming increasingly more powerful, however, the gains that have been made in the device performance has resulted in the need for significantly higher power to operate the electronics. This issue has been further complicated due to the stagnate growth of battery technology over the past decade. In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user's gait or endurance are avoided. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised. This will be accomplished by replacing the strap buckle with a mechanically amplified piezoelectric stack actuator. Piezoelectric stack actuators have found little use in energy harvesting applications due to their high stiffness which makes straining the material difficult. This issue will be alleviated using a mechanically amplified stack which allows the relatively low forces generated by the pack to be transformed to high forces on the piezoelectric stack. This paper will develop a theoretical model of the piezoelectric buckle and perform experimental testing to validate the model accuracy and energy harvesting performance.

  1. Analysis and Design of a Linear Digital Programmable Gain Amplifier in a 0.13 µm SiGe BiCMOS technology

    NASA Astrophysics Data System (ADS)

    Du, Xuan-Quang; Knobloch, Anselm; Grözing, Markus; Buck, Matthias; Berroth, Manfred

    2017-03-01

    This paper presents the analysis and the design of a fully-differential digital programmable gain amplifier (PGA) in a 0.13 µm BiCMOS technology. The PGA has a gain control range of 31 dB with 1 dB gain step size and consumes 284 mW from a 3.6 V power supply. At a maximum gain of 25 dB, the PGA exhibits a 3-dB bandwidth of 10.1 GHz. The measured gain error for all 32 possible gain settings is between -0.19/+0.46 dB at 1 GHz. Up to 13 GHz the third harmonic distortion H{D3} stays below -34 dB for all 32 gain settings at a differential output peak-to-peak voltage of 1 V after the last amplifier stage.

  2. A 24dB Gain 51-68GHz Common Source Low Noise Amplifier Using Asymmetric-Layout Transistors

    NASA Astrophysics Data System (ADS)

    Li, Ning; Bunsen, Keigo; Takayama, Naoki; Bu, Qinghong; Suzuki, Toshihide; Sato, Masaru; Kawano, Yoichi; Hirose, Tatsuya; Okada, Kenichi; Matsuzawa, Akira

    At mm-wave frequency, the layout of CMOS transistors has a larger effect on the device performance than ever before in low frequency. In this work, the distance between the gate and drain contact (Dgd) has been enlarged to obtain a better maximum available gain (MAG). By using the asymmetric-layout transistor, a 0.6dB MAG improvement is realized when Dgd changes from 60nm to 200nm. A four-stage common-source low noise amplifier is implemented in a 65nm CMOS process. A measured peak power gain of 24dB is achieved with a power dissipation of 30mW from a 1.2-V power supply. An 18dB variable gain is also realized by adjusting the bias voltage. The measured 3-dB bandwidth is about 17GHz from 51GHz to 68GHz, and noise figure (NF) is from 4.0dB to 7.6dB.

  3. Cooperative upconversion as the gain-limiting factor in Er doped miniature Al2O3 optical waveguide amplifiers

    NASA Astrophysics Data System (ADS)

    Kik, P. G.; Polman, A.

    2003-05-01

    Erbium doped Al2O3 waveguide amplifiers were fabricated using two different doping methods, namely Er ion implantation into sputter deposited Al2O3, and co-sputtering from an Er2O3/Al2O3 target. Although the Er concentration in both materials is almost identical (0.28 and 0.31 at. %), the amplifiers show a completely different behavior. Upon pumping with 1.48 μm, the co-sputtered waveguide shows a strong green luminescence from the 4S3/2 level, indicating efficient cooperative upconversion in this material. This is confirmed by pump power dependent measurements of the optical transmission at 1.53 μm and the spontaneous emission at 1.53 and 0.98 μm. All measurements can be accurately modeled using a set of rate equations that include first order and second order cooperative upconversion. The first order cooperative upconversion coefficient C24 is found to be 3.5×10-16 cm3 s-1 in the co-sputtered material, two orders of magnitude higher than the value obtained in Er implanted Al2O3 of 4.1×10-18 cm3 s-1. It is concluded that the co-sputtering process results in a strongly inhomogeneous atomic scale spatial distribution of the Er ions. As a result, the co-sputtered waveguides do not show optical gain, while the implanted waveguides do.

  4. Potential impact of contrails on solar energy gain

    NASA Astrophysics Data System (ADS)

    Weihs, P.; Rennhofer, M.; Baumgartner, D.; Gadermaier, J.; Wagner, J.; Laube, W.

    2014-08-01

    We investigated the effect of contrails on global shortwave radiation and on solar energy gain. The study was done for days with a high contrail persistence and looking at situations where the contrails were obstructing the sun. Measurements of cloudiness using a fish eye camera, diffuse and direct shortwave measurements and measurements of the short circuit current of three different types of photovoltaic (PV) modules were performed at the solar observatory Kanzelhöhe (1540 m a.s.l.) during a period of one year with a time resolution of one minute. Our results show that contrails moving between sun and observer/sensor may reduce the global radiation by up to 72%. A statistic of contrail persistence and influence of contrails on global irradiance and solar energy gain is presented. The losses in solar energy gain that were recorded may even be critical under some circumstances for PV system performance.

  5. Potential impact of contrails on solar energy gain

    NASA Astrophysics Data System (ADS)

    Weihs, P.; Rennhofer, M.; Baumgartner, D. J.; Gadermaier, J.; Wagner, J. E.; Gehring, J. E.; Laube, W.

    2015-03-01

    The effect of contrails on global short-wave radiation (sum of direct and downward diffuse solar radiation) and on solar energy gain was investigated. The study was performed during days with high contrail persistence and focused on situations where the contrails were obstructing the sun. Measurements of cloudiness using a fish-eye camera, diffuse and direct short-wave measurements and measurements of the short circuit current of three different types of photovoltaic (PV) modules were performed at the Kanzelhöhe Observatory (1540 m a.s.l.) with a time resolution of 1 min over a period of 1 year. The results show that contrails moving between sun and observer/sensor may reduce the global radiation by up to 72%. An analysis of contrail persistence and the influence of contrails on global irradiance and solar energy gain is presented. The losses in solar energy gain that were recorded may be critical under specific circumstances.

  6. Monolithically integrated quantum dot optical gain modulator with semiconductor optical amplifier for 10-Gb/s photonic transmission

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-03-01

    Short-range interconnection and/or data center networks require high capacity and a large number of channels in order to support numerous connections. Solutions employed to meet these requirements involve the use of alternative wavebands to increase the usable optical frequency range. We recently proposed the use of the T- and O-bands (Thousand band: 1000-1260 nm, Original band: 1260-1360 nm) as alternative wavebands because large optical frequency resources (>60 THz) can be easily employed. In addition, a simple and compact Gb/s-order high-speed optical modulator is a critical photonic device for short-range communications. Therefore, to develop an optical modulator that acts as a highfunctional photonic device, we focused on the use of self-assembled quantum dots (QDs) as a three-dimensional (3D) confined structure because QD structures are highly suitable for realizing broadband optical gain media in the T+O bands. In this study, we use the high-quality broadband QD optical gain to develop a monolithically integrated QD optical gain modulator (QD-OGM) device that has a semiconductor optical amplifier (QD-SOA) for Gb/s-order highspeed optical data generation in the 1.3-μm waveband. The insertion loss of the device can be compensated through the SOA, and we obtained an optical gain change of up to ~7 dB in the OGM section. Further, we successfully demonstrate a 10-Gb/s clear eye opening using the QD-OGM/SOA device with a clock-data recovery sequence at the receiver end. These results suggest that the monolithic QD-EOM/SOA is suitable for increasing the number of wavelength channels for smart short-range communications.

  7. High-intensity resistance training amplifies muscle hypertrophy and functional gains in persons with Parkinson's disease.

    PubMed

    Dibble, Leland E; Hale, Tessa F; Marcus, Robin L; Droge, John; Gerber, J Parry; LaStayo, Paul C

    2006-09-01

    with PD. Additional research is needed to determine the anatomical and neurological mechanisms of the observed strength gains and mobility improvements.

  8. Headwater Benefits Energy Gains (HWBEG) model description and users manual

    SciTech Connect

    Perlack, R D; Turhollow, Jr, A F; Cohn, S M; Das, S; Rizy, C G; Tulley, Jr, J H; Kraemer, R D

    1984-02-01

    The Headwater Benefits Energy Gains (HWBEG) Model was developed for computing energy gains in complex regulated river basins. The model requires daily data on streamflows, storage changes at reservoirs, and power generation at hydroelectric plants. Mathematical relationships are derived from these data to explain the operation of storage reservoirs and the rating of hydropower plants. The HWBEG model assembles streamflows that would have been theoretically available for energy production under varying conditions of upstream reservoir operation. The model first eliminates all upstream storage changes to simulate an unregulated natural flow condition. The storage changes of upstream reservoirs are then added back to the unregulated natural flow in a sequence corresponding to the time the reservoirs began affecting streamflows. As each reservoir is added back to the river system, the hydropower generation attributable to that particular flow is calculated using the reservoir operating rules and the hydropower plant rating curves. Energy gains are determined by subtracting generation with from generation without the chronologically sequenced and combinatorial effects of the upstream storage reservoirs. The energy gains attributable to each storage reservoir are totalled yearly and become the basis for apportioning the cost of operating the upstream federal reservoir or headwater improvement. This report describes the operation of the model including the assembly of the requisite data bases and the use of the computer code.

  9. Application of small-signal fusion energy gain

    SciTech Connect

    Jassby, D.L.

    1986-11-01

    The measured burnup fraction of the 1-MeV tritons produced in a deuterium tokamak plasma, multiplied by 17.5, is essentially the small-signal fusion energy gain g/sub T/ for an ideal 1-MeV triton beam injected into the deuterium plasma. The measured g/sub T/ can be converted directly into the two-component fusion energy gain that would be realized if a lower energy tritium beam were injected into the plasma, or if a deuterium beam were injected into a tritium target plasma having the same parameters as the acutal deuterium plasma. Under certain conditions, g/sub T/ greater than or equal to 1 can be obtained by injection of a low-current 225-keV tritium beam into a hot deuterium plasma, thereby verifying that the plasma has the essential characteristics needed for achieving macroscopic fusion energy ''break-even.''

  10. Optical implementation of neural learning algorithms based on cross-gain modulation in a semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Wang, Zhi; Le, Yansi; Sun, Chonghui; Song, Xiaojia; Wu, Chongqing

    2016-10-01

    Neuromorphic engineering has a wide range of applications in the fields of machine learning, pattern recognition, adaptive control, etc. Photonics, characterized by its high speed, wide bandwidth, low power consumption and massive parallelism, is an ideal way to realize ultrafast spiking neural networks (SNNs). Synaptic plasticity is believed to be critical for learning, memory and development in neural circuits. Experimental results have shown that changes of synapse are highly dependent on the relative timing of pre- and postsynaptic spikes. Synaptic plasticity in which presynaptic spikes preceding postsynaptic spikes results in strengthening, while the opposite timing results in weakening is called antisymmetric spike-timing-dependent plasticity (STDP) learning rule. And synaptic plasticity has the opposite effect under the same conditions is called antisymmetric anti-STDP learning rule. We proposed and experimentally demonstrated an optical implementation of neural learning algorithms, which can achieve both of antisymmetric STDP and anti-STDP learning rule, based on the cross-gain modulation (XGM) within a single semiconductor optical amplifier (SOA). The weight and height of the potentitation and depression window can be controlled by adjusting the injection current of the SOA, to mimic the biological antisymmetric STDP and anti-STDP learning rule more realistically. As the injection current increases, the width of depression and potentitation window decreases and height increases, due to the decreasing of recovery time and increasing of gain under a stronger injection current. Based on the demonstrated optical STDP circuit, ultrafast learning in optical SNNs can be realized.

  11. Irreversible energy gain by linear and nonlinear oscillators

    NASA Astrophysics Data System (ADS)

    Bauer, D.; Mulser, P.

    2005-01-01

    A particle can gain appreciable irreversible energy ("absorption") from linear or nonlinear oscillations only by ballistic excitation ("collision") or, if excited by an adiabatic pulse of constant frequency, by undergoing resonance. For the linear oscillator it is shown that the transition from ballistic to adiabatic behavior out of resonance occurs for sin2-pulses 2 4 eigenperiod long. In the case of a linear oscillator with time-varying eigenfrequency it is shown that Cornu's double spiral represents an attractor, either for zero energy gain out of resonance or finite gain by transiting through resonance. One of the remarkable properties of nonlinear oscillators is that resonance depends on the level of excitation. It is this property which opens a new access to understanding the dominant heating process at high laser intensities, the so-called collisionless absorption phase in solids, extended cluster media, dusty plasmas, and sprays, well guaranteed by experiments and computer simulations but hitherto not well understood in physical terms.

  12. Effect of stimulated Brillouin scattering on the gain saturation of distributed fiber Raman amplifier and its suppression by phase modulation

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Chi; Chen, Wei; Sun, Shi-Lin; Meng, Zhou

    2015-09-01

    For distributed fiber Raman amplifiers (DFRAs), stimulated Brillouin scattering (SBS) can deplete the pump once occurring and consequently generate gain saturation. On the basis of such a theory, theoretical gain saturation powers in DFRAs with various pump schemes are obtained by calculating SBS thresholds in them, and the experimental results show that they are in excellent agreement with the calculation results. The saturation power of the DFRA with a 300 mW forward pump is as low as 0 dBm, which needs to be enhanced by phase modulation, and the effect is quantitatively studied. A simple model taking both modulation frequency and index into consideration is presented by introducing a correction factor to evaluate the effect of phase modulation on the enhancement of saturation power. Experimentally, it is shown that such a correction factor decreases as the modulation frequency increases and approaches zero when the modulation frequency becomes high enough. In particular, a phase modulation with a modulation frequency of 100 MHz and a modulation index of 1.380 can enhance the saturation power by 4.44 dB, and the correction factor is 0.25 dB, in which the modulation frequency is high enough. Additionally, the factor is 1.767 dB for the modulation frequency of 25 MHz. On this basis, phase modulations with various indexes and a fixed frequency of 25 MHz are adopted to verify the modified model, and the results are positive. To obtain the highest gain saturation power, the model is referable. The research results provide a guide for the design of practical DFRAs. Project supported by the National Natural Science Foundation of China (Grant No. 61177073) and the Major Application Basic Research Project of National University of Defense Technology, China (Grant No. ZDYYJCYJ20140701).

  13. Two-stage optical parametric amplifier of a low energy nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Bagdasarov, V. Kh; Bel'kov, S. A.; Garanin, S. G.; Garnov, S. V.; Nikolaev, D. A.; Orlov, S. N.; Polivanov, Y. N.; Sadovskiy, S. P.; Shcherbakov, I. A.; Tsvetkov, V. B.

    2017-05-01

    A two-stage optical parametric amplifier (OPA) design that provides over  -5  ×  107 gain at 1053 nm is presented. Noise level of the parametric amplifier in the signal wave propagation direction was 2  ×  10-6 from the signal level. The parasitic parametric oscillation under intense pump wave and its contribution to the OPA output was measured to be less than 8%.

  14. Experimental study of a modulated beam AlGaAs/GaAs diode amplifier operating in the highly saturated gain regime

    SciTech Connect

    D'yachkov, N V; Bogatov, A P; Gushchik, T I; Drakin, A E

    2014-11-30

    The variation in the modulation parameters of an optical signal in a diode power amplifier has been studied experimentally. The experimental data obtained agree well with theory that takes into account nonlinear interaction between fields in the gain medium of a laser through inversion beating. It is shown that the dominant type of output signal modulation is phase modulation, whose depth depends on the amplitude – phase coupling coefficient of the gain medium of the amplifier and the nature of the modulation (the phase relationships between the spectral components) of the output signal. (lasers)

  15. The energy transfer between the ports of an implemented gyrator using LM13700 operational transconductance amplifier.

    PubMed

    Tatai, Ildiko; Zaharie, Ioan

    2012-11-01

    In this paper a gyrator implementation using a LM13700 operational transconductance amplifier is analyzed. It was first verified under PSpice simulation and experimentally the antireciprocity of this gyrator, i.e., its properties. This type of gyrator can be used for controlling the energy transfer from one port to the other by modifying the bias currents of the operational transconductance amplifier.

  16. The energy transfer between the ports of an implemented gyrator using LM13700 operational transconductance amplifier

    NASA Astrophysics Data System (ADS)

    Tatai, Ildiko; Zaharie, Ioan

    2012-11-01

    In this paper a gyrator implementation using a LM13700 operational transconductance amplifier is analyzed. It was first verified under PSpice simulation and experimentally the antireciprocity of this gyrator, i.e., its properties. This type of gyrator can be used for controlling the energy transfer from one port to the other by modifying the bias currents of the operational transconductance amplifier.

  17. Dynamic energy-balance model predicting gestational weight gain123

    PubMed Central

    Thomas, Diana M; Navarro-Barrientos, Jesus E; Rivera, Daniel E; Heymsfield, Steven B; Bredlau, Carl; Redman, Leanne M; Martin, Corby K; Lederman, Sally A; M Collins, Linda; Butte, Nancy F

    2012-01-01

    Background: Gestational weight gains (GWGs) that exceed the 2009 Institute of Medicine recommended ranges increase risk of long-term postpartum weight retention; conversely, GWGs within the recommended ranges are more likely to result in positive maternal and fetal outcomes. Despite this evidence, recent epidemiologic studies have shown that the majority of pregnant women gain outside the target GWG ranges. A mathematical model that predicts GWG and energy intake could provide a clinical tool for setting precise goals during early pregnancy and continuous objective feedback throughout pregnancy. Objective: The purpose of this study was to develop and validate a differential equation model for energy balance during pregnancy that predicts GWG that results from changes in energy intakes. Design: A set of prepregnancy BMI–dependent mathematical models that predict GWG were developed by using data from a longitudinal study that measured gestational-changes in fat-free mass, fat mass, total body water, and total energy expenditure in 63 subjects. Results: Mathematical models developed for women with low, normal, and high prepregnancy BMI were shown to fit the original data. In 2 independent studies used for validation, model predictions of fat-free mass, fat mass, and total body water matched actual measurements within 1 kg. Conclusions: Our energy-balance model provides plausible predictions of GWG that results from changes in energy intakes. Because the model was implemented as a Web-based applet, it can be widely used by pregnant women and their health care providers. PMID:22170365

  18. High-power, variable repetition rate, picosecond optical parametric oscillator pumped by an amplified gain-switched diode.

    PubMed

    Kienle, Florian; Chen, Kang K; Alam, Shaif-Ul; Gawith, Corin B E; Mackenzie, Jacob I; Hanna, David C; Richardson, David J; Shepherd, David P

    2010-04-12

    We demonstrate a picosecond optical parametric oscillator (OPO) that is synchronously pumped by a fiber-amplified gain-switched laser diode. At 24W of pump power, up to 7.3W at 1.54microm and 3.1W at 3.4microm is obtained in separate output beams. The periodically poled MgO-doped LiNbO(3) OPO operates with ~17ps pulses at a fundamental repetition rate of 114.8MHz but can be switched to higher repetition rates up to ~1GHz. Tunabilty between 1.4microm and 1.7microm (signal) and 2.9microm and 4.4microm (idler) is demonstrated by translating the nonlinear crystal to access different poling-period gratings and typical M(2) values of 1.1 by 1.2 (signal) and 1.6 by 3.2 (idler) are measured at high power for the singly resonant oscillator.

  19. Two-wavelength pump-probe technique using single distributed feedback laser array to probe gain recovery of an erbium-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Kuroda, Keiji; Yoshikuni, Yuzo

    2017-03-01

    We propose a two-wavelength pump-probe technique to probe the gain recovery characteristics of an erbium-doped fiber amplifier. The two-wavelength pulse pairs are generated through the direct modulation of a single distributed feedback laser array. The proposed technique allows us to measure the wavelength dependence of the recovery time after gain saturation is induced by a signal of the same wavelength.

  20. Effect of additional optical pumping injection into the ground-state ensemble on the gain and the phase recovery acceleration of quantum-dot semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Kim, Jungho

    2014-02-01

    The effect of additional optical pumping injection into the ground-state ensemble on the ultrafast gain and the phase recovery dynamics of electrically-driven quantum-dot semiconductor optical amplifiers is numerically investigated by solving 1088 coupled rate equations. The ultrafast gain and the phase recovery responses are calculated with respect to the additional optical pumping power. Increasing the additional optical pumping power can significantly accelerate the ultrafast phase recovery, which cannot be done by increasing the injection current density.

  1. Suppression of thermal lens effect in high-pulse-energy Ti:sapphire amplifiers

    NASA Astrophysics Data System (ADS)

    Wu, Fenxiang; Yu, Linpeng; Lu, Jun; Li, Wenkai; Xu, Yi; Leng, Yuxin

    2017-01-01

    In high-pulse-energy Ti:sapphire amplifiers with moderate repetition rate, the thermal lens effect can significantly decrease the energy extraction efficiency and increase the risk of optical damage. A new method, without introducing any additional components, is proposed to suppress the thermal lens effect in such amplifiers. By utilizing a particularly designed beam expander before the amplifier, specific expanding ratio and beam divergence can be introduced to the injected seed pulses, which can improve the spatial matching between the seed pulses and the pump pulses, and thus enhance the energy extraction efficiency. The enhancement of the energy extraction efficiency has reached approximately 10% in our experimental four-pass Ti:sapphire amplifier, and the good agreement between theoretical and experimental results also demonstrates the validity and feasibility of this method.

  2. Output Energy Fluctuations of the Nd:YAG Amplifier Chain of a Photoinjector Drive Laser System.

    PubMed

    Le Flanchec, V

    1998-09-20

    In the Etude d'un LaSer Accordable, electron bunches consist of trains of picosecond pulses extracted from a photocathode by a drive laser system: This system consists of a mode-locked Nd:YAG oscillator followed by a pulse compressor, an amplifier chain, and a second-harmonic-generation stage. The performance of the linac critically depends on the energy stability of this system. It is demonstrated theoretically and experimentally that the energy fluctuations of the Nd:YAG oscillator are significantly reduced by the amplifier chain, that the remaining energy fluctuations of the whole system are mainly due to amplifier pump fluctuations, and that the amplifier chain can be optimized to reduce the global energy fluctuations from 1.5% rms to <1% rms.

  3. PULSE AMPLIFIER

    DOEpatents

    Johnstone, C.W.

    1958-06-17

    The improvement of pulse amplifiers used with scintillation detectors is described. The pulse amplifier circuit has the advantage of reducing the harmful effects of overloading cause by large signal inputs. In general the pulse amplifier circuit comprises two amplifier tubes with the input pulses applied to one amplifier grid and coupled to the second amplifier tube through a common cathode load. The output of the second amplifier is coupled from the plate circuit to a cathode follower tube grid and a diode tube in connected from grid to cathode of the cathode follower tube. Degenerative feedback is provided in the second amplifier by coupling a signal from the cathode follower cathode to the second amplifier grid. The circuit proqides moderate gain stability, and overload protection for subsequent pulse circuits.

  4. A novel low-noise linear-in-dB intermediate frequency variable-gain amplifier for DRM/DAB tuners

    NASA Astrophysics Data System (ADS)

    Keping, Wang; Zhigong, Wang; Jianzheng, Zhou; Xuemei, Lei; Mingzhu, Zhou

    2009-03-01

    A broadband CMOS intermediate frequency (IF) variable-gain amplifier (VGA) for DRM/DAB tuners is presented. The VGA comprises two cascaded stages: one is for noise-canceling and another is for signal-summing. The chip is fabricated in a standard 0.18 μm 1P6M RF CMOS process of SMIC. Measured results show a good linear-in-dB gain characteristic in 28 dB dynamic gain range of -10 to 18 dB. It can operate in the frequency range of 30-700 MHz and consumes 27 mW at 1.8 V supply with the on-chip test buffer. The minimum noise figure is only 3.1 dB at maximum gain and the input-referred 1 dB gain compression point at the minimum gain is -3.9 dBm.

  5. Gain-switched laser diode seeded Yb-doped fiber amplifier delivering 11-ps pulses at repetition rates up to 40-MHz

    NASA Astrophysics Data System (ADS)

    Ryser, Manuel; Neff, Martin; Pilz, Soenke; Burn, Andreas; Romano, Valerio

    2012-02-01

    Here, we demonstrate all-fiber direct amplification of 11 picosecond pulses from a gain-switched laser diode at 1063 nm. The diode was driven at a repetition rate of 40 MHz and delivered 13 μW of fiber-coupled average output power. For the low output pulse energy of 0.33 pJ we have designed a multi-stage core pumped preamplifier based on single clad Yb-doped fibers in order to keep the contribution of undesired amplified spontaneous emission as low as possible and to minimize temporal and spectral broadening. After the preamplifier we reduced the 40 MHz repetition rate to 1 MHz using a fiber coupled pulse-picker. The final amplification was done with a cladding pumped Yb-doped large mode area fiber and a subsequent Yb-doped rod-type fiber. With our setup we achieved amplification of 72 dBs to an output pulse energy of 5.7 μJ, pulse duration of 11 ps and peak power of >0.6 MW.

  6. LOGARITHMIC AMPLIFIER

    DOEpatents

    De Shong, J.A. Jr.

    1957-12-31

    A logarithmic current amplifier circuit having a high sensitivity and fast response is described. The inventor discovered the time constant of the input circuit of a system utilizing a feedback amplifier, ionization chamber, and a diode, is inversely proportional to the input current, and that the amplifier becomes unstable in amplifying signals in the upper frequency range when the amplifier's forward gain time constant equals the input circuit time constant. The described device incorporates impedance networks having low frequency response characteristic at various points in the circuit to change the forward gain of the amplifler at a rate of 0.7 of the gain magnitude for every two times increased in frequency. As a result of this improvement, the time constant of the input circuit is greatly reduced at high frequencies, and the amplifier response is increased.

  7. Laser amplifier and method

    DOEpatents

    Backus, S.; Kapteyn, H.C.; Murnane, M.M.

    1997-07-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethrough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate. 7 figs.

  8. Laser amplifier and method

    DOEpatents

    Backus, Sterling; Kapteyn, Henry C.; Murnane, Margaret M.

    1997-01-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate.

  9. Energy Gain. Teacher's Guide and Student Guide. Net Energy Unit. Draft.

    ERIC Educational Resources Information Center

    McLeod, Richard J.

    This module focuses on gains and losses of energy as society processes resources for energy production. It particularly focuses on the end point of energy conversion and addresses decisions which society must make concerning benefits and costs of various energy production methods and generating facilities. One class period is needed to implement…

  10. Energy intake and energy expenditure for determining excess weight gain in pregnant women

    USDA-ARS?s Scientific Manuscript database

    To conduct a secondary analysis designed to test whether gestational weight gain is the result of increased energy intake or adaptive changes in energy expenditures. In this secondary analysis, energy intake and energy expenditure of 45 pregnant women (body mass index [BMI] 18.5-24.9 [n=33] and BMI ...

  11. PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Ultimate values of the gain of solid-state rod amplifiers operating under inversion storage conditions

    NASA Astrophysics Data System (ADS)

    Bayanov, V. I.; Vinokurov, G. N.; Zhulin, V. I.; Yashin, V. E.

    1989-02-01

    A numerical calculation is reported of an inversion conservation coefficient of cylindrical rod solid-state amplifiers with the active element diameter from 1.5 to 15 cm operated under continuous pumping conditions. It is shown that the ultimate gain, limited only by superluminescence, exceeds considerably the value usually obtained in experiments. Various methods of eliminating parasitic effects, which limit the gain of real amplifiers, are considered. The degree of influence of these effects on the inversion conservation coefficient is discussed. The results are given of an experimental determination of the gain close to the ultimate value (0.18 cm- 1 for an active element 3 cm in diameter). Calculations are reported of the angular distributions of superluminescence and parasitic modes demonstrating that the latter can be suppressed by spatial filtering.

  12. High-energy nanosecond radially polarized beam output from Nd:YAG amplifiers

    NASA Astrophysics Data System (ADS)

    Chang, Chengcheng; Chen, Xudong; Pu, Jixiong

    2017-03-01

    Radially polarized laser beam amplification up to the 772 mJ using flash-lamp-pumped Nd:YAG amplifiers was demonstrated. In the experiments, a nanosecond radially polarized seed beam was converted from a conventional Q-switched Nd:YAG laser output with a polarization converter and then amplified with two Nd:YAG amplifier stages. A maximum amplification output energy up to 772 mJ was achieved at 10 Hz with a 10-ns pulse, corresponding to an amplification factor of 323%. Excellent conservation of polarization was also obtained during the amplification.

  13. Low energy intake plus low energy expenditure (low energy flux), not energy surfeit, predicts future body fat gain12

    PubMed Central

    Yokum, Sonja; Stice, Eric

    2016-01-01

    Background: There is a paucity of studies that have prospectively tested the energy surfeit theory of obesity with the use of objectively estimated energy intake and energy expenditure in humans. An alternative theory is that homeostatic regulation of body weight is more effective when energy intake and expenditure are both high (high energy flux), implying that low energy flux should predict weight gain. Objective: We aimed to examine the predictive relations of energy balance and energy flux to future weight gain and tested whether results were replicable in 2 independent samples. Design: Adolescents (n = 154) and college-aged women (n = 75) underwent 2-wk objective doubly labeled water, resting metabolic rate, and percentage of body fat measures at baseline. Percentage of body fat was measured annually for 3 y of follow-up for the adolescent sample and for 2 y of follow-up for the young adult sample. Results: Low energy flux, but not energy surfeit, predicted future increases in body fat in both studies. Furthermore, high energy flux appeared to prevent fat gain in part because it was associated with a higher resting metabolic rate. Conclusion: Counter to the energy surfeit model of obesity, results suggest that increasing energy expenditure may be more effective for reducing body fat than caloric restriction, which is currently the treatment of choice for obesity. This trial was registered at clinicaltrials.gov as NCT02084836. PMID:27169833

  14. Low energy intake plus low energy expenditure (low energy flux), not energy surfeit, predicts future body fat gain.

    PubMed

    Hume, David John; Yokum, Sonja; Stice, Eric

    2016-06-01

    There is a paucity of studies that have prospectively tested the energy surfeit theory of obesity with the use of objectively estimated energy intake and energy expenditure in humans. An alternative theory is that homeostatic regulation of body weight is more effective when energy intake and expenditure are both high (high energy flux), implying that low energy flux should predict weight gain. We aimed to examine the predictive relations of energy balance and energy flux to future weight gain and tested whether results were replicable in 2 independent samples. Adolescents (n = 154) and college-aged women (n = 75) underwent 2-wk objective doubly labeled water, resting metabolic rate, and percentage of body fat measures at baseline. Percentage of body fat was measured annually for 3 y of follow-up for the adolescent sample and for 2 y of follow-up for the young adult sample. Low energy flux, but not energy surfeit, predicted future increases in body fat in both studies. Furthermore, high energy flux appeared to prevent fat gain in part because it was associated with a higher resting metabolic rate. Counter to the energy surfeit model of obesity, results suggest that increasing energy expenditure may be more effective for reducing body fat than caloric restriction, which is currently the treatment of choice for obesity. This trial was registered at clinicaltrials.gov as NCT02084836. © 2016 American Society for Nutrition.

  15. Femtosecond pulse spectral synthesis in coherently-spectrally combined multi-channel fiber chirped pulse amplifiers.

    PubMed

    Chang, Wei-zung; Zhou, Tong; Siiman, Leo A; Galvanauskas, Almantas

    2013-02-11

    We demonstrate coherent spectral beam combining and femtosecond pulse spectral synthesis using three parallel fiber chirped pulse amplifiers, each amplifying different ultrashort-pulse spectra. This proof-of-concept experiment opens a path to simultaneously overcome individual-amplifier energy and power limitations, as well as limitations on amplified pulse spectra due to the gain narrowing in a single fiber amplifier.

  16. A Novel Bi-wavelength Method for Accurately Measuring Gain and Noise Characteristics of an Erbium-Doped Fibre Amplifier for Multi-Channel Wavelength Division Multiplexing Transmission

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Ge; Meng, Hong-Yun; Yuan, Shu-Zhong; Tian, Jian-Guo; Kai, Gui-Yun; Dong, Xiao-Yi

    2003-10-01

    Gain and noise figure (NF) are the most important two parameters of an erbium-doped fibre amplifier (EDFA) for a multi-channel wavelength division multiplexing (WDM) transmission system. A simple bi-wavelength method for accurate gain and NF spectrum measurement of EDFA for WDM applications is proposed. A saturating input signal, whose power equals to the sum of all the WDM signal power and whose wavelength is determined by the channel numbers, and the wavelength of the WDM input signals saturates the EDFA in a degree as the same as the WDM signals input. Meanwhile, a small power probe signal scans and measures the gain and the NF value at every wavelength of the WDM input signals. Investigative results by numerical simulation show that the gain and the NF spectra measured by this method have good agreement with the real spectra of the WDM signal input in a large total input power range. The maximum errors of the gain and the NF are less than 0.2 dB and 0.16 dB, respectively, for a 50-channel input case. The method is competent for the accurate gain and the NF spectrum measurement of the fibre preamplifier and the line-amplifier for WDM applications and has the advantages of simplicity, convenience and easy implement.

  17. Active cavity stabilization for high energy thin disk regenerative amplifier

    NASA Astrophysics Data System (ADS)

    Boge, Robert; Horáček, Jakub; Maz&oring; rek, Petr; Naylon, Jack Alexander; Novák, Jakub; Batysta, František; Hubka, Zbyněk.; Šobr, Václav; Antipenkov, Roman; Green, Jonathan T.; Bakule, Pavel; Rus, Bedřich

    2017-05-01

    We present an active cavity pointing stabilization system based on a novel method that tracks the cavity mode position directly on the thin disk gain medium itself. Here, the overlap of the lasing cavity with the pump, visible as a depletion within the pumped area, is most crucial to the stability of the laser. Short term stability as well as long term stability are significantly increased enabling day long operation, directly from a cold start of the laser system, without the need for thermalization and manual alignment.

  18. Method for generating high-energy and high repetition rate laser pulses from CW amplifiers

    SciTech Connect

    Zhang, Shukui

    2013-06-18

    A method for obtaining high-energy, high repetition rate laser pulses simultaneously using continuous wave (CW) amplifiers is described. The method provides for generating micro-joule level energy in pico-second laser pulses at Mega-hertz repetition rates.

  19. On-Wafer Measurement of a Multi-Stage MMIC Amplifier with 10 dB of Gain at 475 GHz

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene A.; Fung, KingMan; Pukala, David M.; Kangaslahti, Pekka P.; Lai, Richard; Ferreira, Linda

    2012-01-01

    JPL has measured and calibrated a WR2.2 waveguide wafer probe from GGB Industries in order to allow for measurement of circuits in the 325-500 GHz range. Circuits were measured, and one of the circuits exhibited 10 dB of gain at 475 GHz. The MMIC circuit was fabricated at Northrop Grumman Corp. (NGC) as part of a NASA Innovative Partnerships Program, using NGC s 35-nm-gatelength InP HEMT process technology. The chip utilizes three stages of HEMT amplifiers, each having two gate fingers of 10 m in width. The circuits use grounded coplanar waveguide topology on a 50- m-thick substrate with through substrate vias. Broadband matching is achieved with coplanar waveguide transmission lines, on-chip capacitors, and open stubs. When tested with wafer probing, the chip exhibited 10 dB of gain at 475 GHz, with over 9 dB of gain from 445-490 GHz. Low-noise amplifiers in the 400-500 GHz range are useful for astrophysics receivers and earth science remote sensing instruments. In particular, molecular lines in the 400-500 GHz range include the CO 4-3 line at 460 GHz, and the CI fine structure line at 492 GHz. Future astrophysics heterodyne instruments could make use of high-gain, low-noise amplifiers such as the one described here. In addition, earth science remote sensing instruments could also make use of low-noise receivers with MMIC amplifier front ends. Present receiver technology typically employs mixers for frequency down-conversion in the 400-500 GHz band. Commercially available mixers have typical conversion loss in the range of 7-10 dB with noise figure of 1,000 K. A low-noise amplifier placed in front of such a mixer would have 10 dB of gain and lower noise figure, particularly if cooled to low temperature. Future work will involve measuring the noise figure of this amplifier.

  20. Helical Fiber Amplifier

    DOEpatents

    Koplow, Jeffrey P.; Kliner, Dahy; Goldberg, Lew

    2002-12-17

    A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).

  1. Low cost instrumentation amplifier

    NASA Technical Reports Server (NTRS)

    Sturman, J. C.

    1974-01-01

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

  2. A 16.9 dBm InP DHBT W-band power amplifier with more than 20 dB gain

    NASA Astrophysics Data System (ADS)

    Hongfei, Yao; Yuxiong, Cao; Danyu, Wu; Xiaoxi, Ning; Yongbo, Su; Zhi, Jin

    2013-07-01

    A two-stage MMIC power amplifier has been realized by use of a 1-μm InP double heterojunction bipolar transistor (DHBT). The cascode structure, low-loss matching networks, and low-parasite cell units enhance the power gain. The optimum load impedance is determined from load-pull simulation. A coplanar waveguide transmission line is adopted for its ease of fabrication. The chip size is 1.5 × 1.7 mm2 with the emitter area of 16 × 1 μm × 15 μm in the output stage. Measurements show that small signal gain is more than 20 dB over 75.5-84.5 GHz and the saturated power is 16.9 dBm @ 79 GHz with gain of 15.2 dB. The high power gain makes it very suitable for medium power amplification.

  3. Rate of energy gain and maximum energy in diffusive shock acceleration. [astrophysical implications

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1987-01-01

    The problem of diffusive shock acceleration of fast charged particles is reexamined with emphasis on the rate of energy gain, and the maximum energy which can be attained in a given circumstance. The direction of the average magnetic field at the shock is shown to have a large effect. If the perpendicular diffusion coefficient is much smaller than the parallel coefficient, particles can gain much more energy if the shock is quasi-perpendicular than if it is quasi-parallel. The maximum energy attainable can be substantially higher (by a factor of 100 or more) than previous discussions would predict, in cases where the shock is quasi-perpendicular. The energy gain increases as kappa-perpendicular decreases. The principal limitation comes from the requirement that diffusion be a valid approximation to the particle motion, and that the particle be able to diffuse fast enough to encounter the shock many times.

  4. Design of a 0.13 µm SiGe Limiting Amplifier with 14.6 THz Gain-Bandwidth-Product

    NASA Astrophysics Data System (ADS)

    Park, Sehoon; Du, Xuan-Quang; Grözing, Markus; Berroth, Manfred

    2017-09-01

    This paper presents the design of a limiting amplifier with 1-to-3 fan-out implementation in a 0.13 µm SiGe BiCMOS technology and gives a detailed guideline to determine the circuit parameters of the amplifier for optimum high-frequency performance based on simplified gain estimations. The proposed design uses a Cherry-Hooper topology for bandwidth enhancement and is optimized for maximum group delay flatness to minimize phase distortion of the input signal. With regard to a high integration density and a small chip area, the design employs no passive inductors which might be used to boost the circuit bandwidth with inductive peaking. On a RLC-extracted post-layout simulation level, the limiting amplifier exhibits a gain-bandwidth-product of 14.6 THz with 56.6 dB voltage gain and 21.5 GHz 3 dB bandwidth at a peak-to-peak input voltage of 1.5 mV. The group delay variation within the 3 dB bandwidth is less than 0.5 ps and the power dissipation at a power supply voltage of 3 V including output drivers is 837 mW.

  5. Scaling of gain with energy spread and energy in the PEP FEL

    SciTech Connect

    Fisher, A.S.

    1992-07-13

    The Sag Harbor paper on the PEP FEL discusses the scaling of various FEL parameters with energy spread {sigma}{sub {var epsilon}}. I will repeat some of this material here and then examine the benefit of increasing the energy spread. How much energy spread can be achieved with damping wigglers is the next topic. Finally, I consider the dependence of gain and saturation length on beam energy and undulator field.

  6. Scaling of gain with energy spread and energy in the PEP FEL

    SciTech Connect

    Fisher, A.S.

    1992-07-13

    The Sag Harbor paper on the PEP FEL discusses the scaling of various FEL parameters with energy spread {sigma}{sub {var_epsilon}}. I will repeat some of this material here and then examine the benefit of increasing the energy spread. How much energy spread can be achieved with damping wigglers is the next topic. Finally, I consider the dependence of gain and saturation length on beam energy and undulator field.

  7. Generation of 25-ns pulses with a peak power of over 10 kW from a gain-switched, 2-mm Tm-doped fibre laser and amplifier system

    SciTech Connect

    Swiderski, J; Michalska, M; Pichola, W; Mamajek, M

    2014-04-28

    We report on an all-fibre, gain-switched, Tm{sup 3+}-doped silica fibre laser and amplifier system generating a train of pulses at a wavelength of 1994.4 nm. When operating at a pulse repetition frequency f=''100'' kHz, it delivered the maximum average power as high as 9.03 W with a slope efficiency of 36.4%. At f = 26 kHz, stable 25-ns pulses with an energy of 0.28 mJ corresponding to a peak power of 10.5 kW were obtained. The performance of the laser system is described. (lasers)

  8. Wavelength tunable alexandrite regenerative amplifier

    SciTech Connect

    Harter, D.J.; Bado, P.

    1988-11-01

    We describe a wavelength tunable alexandrite regenerative amplifier which is used to amplify nanosecond slices from a single-frequency cw dye laser or 50-ps pulses emitted by a diode laser to energies in the 10-mJ range. The amplified 5-ns slices generated by the cw-pumped line narrowed dye laser are Fourier transform limited. The 50-ps pulses emitted by a gain-switched diode laser are amplified by more than 10 orders of magnitude in a single stage.

  9. Gain Characteristics of Polymer Waveguide Amplifiers Based on NaYF4:Ybl+, Er3+ Nanocrystals at 0.54 µm Wavelength.

    PubMed

    Zhang, Meiling; Yin, Jiao; Jia, Zhixu; Song, Weiye; Wang, Xibin; Qin, Guanshi; Zhao, Dan; Qin, Weiping; Wang, Fei; Zhang, Daming

    2016-04-01

    Gain characteristics of polymer waveguide amplifiers based on NaYF4:Yb3+, Er3+ nanocrystals (NCs) at 0.54 µm wavelength were investigated through numerical simulations. NaYF4:18%Yb3+, 1 0%Er3+ NCs were doped into SU-8 2005 polymer matrix as the core of a polymer waveguide. The absorption spectrum and photoluminescence spectrum of the NCs were recorded and analyzed. The Judd-Ofelt parameters were achieved by means of Judd-Ofelt theory: Ω2 = 6.302 x 10(-20) cm2, Ω4 = 0.69 x 10(-20) cm2, Ω6 =7.572 x 10(-20) cm2. We simulated the gain characteristics of the waveguide amplifier at 0.54 µm wavelength by combining the atomic rate equations with power propaga- tion equations. The gain curves had the saturation effects. A maximum gain -4.3 dB for the 5 cm waveguide with the Er3+ concentration of ~7.5 x 1025 m-3 was obtained.

  10. High performance polarization-independent Quantum Dot Semiconductor Optical Amplifier with 22 dB fiber to fiber gain using Mode Propagation Tuning without additional polarization controller

    NASA Astrophysics Data System (ADS)

    Farmani, Ali; Farhang, Mahmoud; Sheikhi, Mohammad H.

    2017-08-01

    A detailed numerical investigation of polarization-independent quantum dot InAs/GaAs semiconductor optical amplifier (PIQS) based on a technique called mode propagation tuning (MPT) without the need for the polarization controller (PC) is reported, which can solve the limitation caused by polarization sensitivity in a semiconductor optical amplifier (SOA). Our calculations show that by a suitable tuning of the thickness of the active layer, only the TE0 and TM0 modes can propagate. Moreover, the gain saturation behavior of this SOA was measured at 1.55 μ m and found to be polarization-independent (PI). At active layer thickness of 1.7 μ m, the confinement factor was 0.75 and 0.7 for TE0 and TM0 modes, respectively, which leads to a gain difference up to 0.1 dB. The rate equations of the QD-SOA were also solved and a fiber to fiber gain of 22 dB was obtained. Additionally, a numerical simulation is presented which shows that the residual gain ripple and polarization sensitivity are sufficiently reduced when residual facet reflectivities of the SOA are in the range below 10-4 . In addition, the full-width at half-maximum of the horizontal and vertical far-field patterns (FFPs) are measured as 30° × 30°. The proposed structure can be used for logical applications.

  11. Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence

    NASA Astrophysics Data System (ADS)

    Lohmeyer, Whitney; Carlton, Ashley; Wong, Frankie; Bodeau, Michael; Kennedy, Andrew; Cahoy, Kerri

    2015-05-01

    The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier anomalies and quantify the high-energy electron environment for periods of time prior to the anomalies. Building on the work of Lohmeyer and Cahoy (2013), we find that anomalies occur at a rate higher than just by chance when the >2 MeV electron fluence accumulated over 14 and 21 days is elevated. To try to understand "why," we model the amplifier subsystem to assess whether the dielectric material in the radio frequency (RF) coaxial cables, which are the most exposed part of the system, is liable to experience electrical breakdown due to internal charging. We find that the accumulated electric field over the 14 and 21 days leading up to the anomalies is high enough to cause the dielectric material in the coax to breakdown. We also find that the accumulated voltages reached are high enough to compromise components in the amplifier system, for example, the direct current (DC) blocking capacitor. An electron beam test using a representative coaxial cable terminated in a blocking capacitor showed that discharges could occur with peak voltages and energies sufficient to damage active RF semiconductor devices.

  12. Effect of wetting-layer density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Kim, Jungho; Yu, Bong-Ahn

    2015-03-01

    We numerically investigate the effect of the wetting-layer (WL) density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers in both electrical and optical pumping schemes by solving 1088 coupled rate equations. The temporal variations of the ultrafast gain and phase recovery responses at the ground state (GS) are calculated as a function of the WL density of states. The ultrafast gain recovery responses do not significantly depend on the WL density of states in the electrical pumping scheme and the three optical pumping schemes such as the optical pumping to the WL, the optical pumping to the excited state ensemble, and the optical pumping to the GS ensemble. The ultrafast phase recovery responses are also not significantly affected by the WL density of states except the optical pumping to the WL, where the phase recovery component caused by the WL becomes slowed down as the WL density of states increases.

  13. Energy Intake and Energy Expenditure for Determining Excess Weight Gain in Pregnant Women.

    PubMed

    Gilmore, L Anne; Butte, Nancy F; Ravussin, Eric; Han, Hongmei; Burton, Jeffrey H; Redman, Leanne M

    2016-05-01

    To conduct a secondary analysis designed to test whether gestational weight gain is the result of increased energy intake or adaptive changes in energy expenditures. In this secondary analysis, energy intake and energy expenditure of 45 pregnant women (body mass index [BMI] 18.5-24.9 [n=33] and BMI 25 or greater [n=12]) were measured preconceptionally and at 22 and 36 weeks of gestation. Energy intake was calculated as the sum of total energy expenditure measured by doubly-labeled water and energy deposition determined by the four-compartment body composition model. Measurements of weight, body composition, and basal metabolic rate were completed preconceptionally and 9, 22, and 36 weeks of gestation. Basal metabolic rate was measured by indirect calorimetry in a room calorimeter and activity energy expenditure by doubly-labeled water. Energy intake from 22 to 36 weeks of gestation was significantly higher in high gainers (n=19) (3,437±99 kcal per day) compared with low+ideal gainers (n=26) (2,687±110, P<.001) within both BMI categories. Basal metabolic rate increased in proportion to gestational weight gain; however, basal metabolic rate adjusted for body composition changes with gestational weight gain was not significantly different between high gainers and low+ideal gainers (151±33 compared with 129±36 kcal per day; P=.66). Activity energy expenditure decreased throughout pregnancy in both groups (low+ideal gainers: -150±70 kcal per day; P=.04 and high gainers: -230±92 kcal per day; P=.01), but there was no difference between high gainers and low+ideal gainers (P=.49). Interventions designed to increase adherence to the Institute of Medicine guidelines for weight gain in pregnancy may have increased efficacy if focused on limiting energy intake while increasing nutrient density and maintaining levels of physical activity.

  14. Energy Intake and Energy Expenditure for Determining Excess Weight Gain in Pregnant Women

    PubMed Central

    Gilmore, L. Anne; Butte, Nancy F.; Ravussin, Eric; Han, Hongmei; Burton, Jeffrey H.; Redman, Leanne M.

    2016-01-01

    Objective To conduct a secondary analysis designed to test whether gestational weight gain is due to increased energy intake or adaptive changes in energy expenditures. Methods In this secondary analysis, energy intake and energy expenditure of 45 pregnant women (BMI 18.5–24.9 kg/m2, n=33 and BMI ≥ 25, n=12) were measured preconceptionally 22, and 36 weeks of gestation. Energy intake was calculated as the sum of total energy expenditure measured by doubly labeled water and energy deposition determined by the 4-compartment body composition model. Weight, body composition, and metabolic chamber measurement were completed preconceptionally, 9, 22, and 36 weeks of gestation. Basal metabolic rate was measured by indirect calorimetry in a room calorimeter and activity energy expenditure by doubly labeled water. Results Energy intake from 22 to 36 weeks of gestation was significantly higher in high gainers (n=19) (3437 ± 99 kcal/d) versus low + ideal gainers (n=26) (2687 ± 110 p< .001) within both BMI categories. Basal metabolic rate increased in proportion to gestational weight gain; however, basal metabolic rate adjusted for body composition changes with gestational weight gain was not significantly different between high gainers and low + ideal gainers (151 ± 33 vs. 129 ± 36 kcal/d; p=.66). Activity energy expenditure decreased throughout pregnancy in both groups (low + ideal gainers: −150 ± 70 kcal/d; p=.04 and high gainers: −230 ± 92 kcal/day; p=.01), but there was no difference between high gainers and low + ideal gainers (p=.49). Conclusion Interventions designed to increase adherence to the IOM guidelines for weight gain in pregnancy may have increased efficacy if focused on limiting energy intake while increasing nutrient density and maintaining levels of physical activity. PMID:27054928

  15. High energy regenerative amplifier based on Yb:CaF2

    NASA Astrophysics Data System (ADS)

    Sevillano, P.; Brisset, J. G.; Trophème, B.; Courjaud, A.

    2017-02-01

    We report on a diode pumped ultrafast amplifier based on Yb:CaF2 delivering 32 mJ, at a repetition rate of up to 200 Hz, with a central wavelength of 1030nm. The pulses have spectral bandwidth of 5.5 nm, supporting a theoretical pulse duration of 250 fs, are compressed to 300 fs in a compressor based on reflection gratings with a transmission efficiency up to 89%. This laser source constitutes an ideal source for pumping nonlinear crystals through Optical Parametric Amplification or Optical rectification. It is also well adapted for seeding ultrafast high energy amplifiers based on Yb:YAG crystals

  16. Required energy for a laser radar system incorporating a fiber amplifier or an avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Overbeck, Jay A.; Salisbury, Michael S.; Mark, Martin B.; Watson, Edward A.

    1995-11-01

    The transmitted energy required for an airborne laser radar system to be able to image a target at 20 km is investigated. Because direct detection is being considered, two methods of using an avalanche photodiode (APD) as the detector and (2) using a commercial fiber amplifier as a preamplifier before a photodetector. For this analysis a specified signal-to-noise ratio was used in conjunction with the radar range equation, which includes the effects of atmospheric transmission and turbulence. Theoretical analysis reveals that a system with a fiber amplifier performs nearly the same as a system incorporating an APD.

  17. H3K9/36me3 Demethylase KDM4A Promotes Site-Specific Copy Gain and Re-replication of Regions Amplified in Tumors

    PubMed Central

    Black, Joshua C.; Manning, Amity; Van Rechem, Capucine; Kim, Jaegil; Ladd, Brendon; Cho, Juok; Pineda, Cristiana M.; Murphy, Nancy; Daniels, Danette L.; Montagna, Cristina; Lewis, Peter W.; Glass, Kimberly; Allis, C. David; Dyson, Nicholas J.; Getz, Gad; Whetstine, Johnathan R.

    2013-01-01

    SUMMARY Acquired chromosomal instability and copy number alterations are hallmarks of cancer. Enzymes capable of promoting site-specific copy number changes have yet to be identified. Here, we demonstrate that H3K9/36me3 lysine demethylase KDM4A/JMJD2A overexpression leads to localized copy gain of 1q12, 1q21, and Xq13.1 without global chromosome instability. KDM4A amplified tumors have increased copy gains for these same regions. 1q12h copy gain occurs within a single cell cycle, requires S phase and is not stable but regenerated each cell division. Sites with increased copy number are re-replicated and have increased KDM4A, MCM and DNA polymerase occupancy. Suv39h1/KMT1A or HP1γ overexpression suppresses the copy gain, while H3K9/K36 methylation interference promotes gain. Our results demonstrate that overexpression of a chromatin modifier results in site-specific copy gains. This begins to establish how copy number changes could originate during tumorigenesis and demonstrates that transient overexpression of specific chromatin modulators could promote these events. PMID:23871696

  18. Factors limiting the sensitivity and dynamic range of a seismic system employing analog magnetic tape recording and a seismic amplifier with adjustable gain settings and several output levels

    USGS Publications Warehouse

    Eaton, Jerry P.; Van Schaack, John R.

    1977-01-01

    In the course of modernizing the low-speed-tape-recorder portable seismic systems and considering the possibilities for the design of a cassette-tape-recorder seismic refraction system, the factors that limit the sensitivity and dynamic range of such systems have been reviewed. These factors will first be stated briefly, and then their influence on systems such as the new 5-day-tape seismic system will be examined in more detail. To fix ideas, we shall assume that the system consists of the following elements: 1. A seismic sensor: usually a moving coil inertial seismometer with a period of about 1 second, a coil resistance of about 5000 ohms, and an effective motor constant of 1.0 V/cm/sec (across a 10K load terminating the seismometer sensitivity-and-damping-adjustment resistive network). 2. A seismic amplifier/voltage controlled oscillator unit made up of the following components: a) A fixed gain preamplifier with an input resistance of 10K and an internal noise level of 0.5 muVpp referred to the preamp input (0.1 Hz <= freq. <= 30 hz). b) An adjustable gain (0 to 42 db in 6 db steps) intermediate amplifier c) One or more fixed gain output amplifiers. d) Two sections of 6 db/octave bandpass filter serving to couple the 3 amplifier stages together. e) Voltage controlled oscillators for each output amplifier to produce modulated FM carriers for recording on separate tape tracks or modulated FM subcarriers for subsequent multiplexing and direct recording on tape in the California Network format. 3. An analog magnetic tape recorder: e.g. the PI 5100 (15/80 ips recording in the FM mode or in the direct mode with the 'broad-band' variant-of the Cal Net multiplex system, or 15/16 ips recording in the direct mode with the standard Cal Net multiplex system), or the Sony TC-126 cassette recorder operating in the direct record mode with the standard Cal Net multiplex system. 4. Appropriate magnetic tape playback equipment: e.g., the Bell and Howell 3700-B for the PI-5100 or

  19. Modeling the distributed gain of single--(1050 or 1410 nm) and dual-wavelength--(800 + 1050 nm or 800 + 1410 nm) pumped thulium-doped fiber amplifiers.

    PubMed

    Floridia, Claudio; Carvalho, M T; Lüthi, S R; Gomes, A S L

    2004-09-01

    The distributed gain of single- and dual-wavelength-pumped thulium-doped fiber amplifiers is modeled. The excellent agreement between the model and coherent optical frequency domain reflectometry measurements enables us to estimate intrinsic loss, branching ratios of fluorescence originating from the 3H4 level, and cross sections of upconversion pumping at 1050 and 1410 nm for the Tm3+ ions in the fiber. With the branching ratios obtained it is possible to describe induced signal absorption when pumping at 800 nm.

  20. An AC modulated near infrared gain calibration system for a “Violin-Mode” transimpedance amplifier, intended for advanced LIGO suspensions

    SciTech Connect

    Lockerbie, N. A.; Tokmakov, K. V.

    2016-07-15

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a “tall-thin” rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse “Violin-Mode” vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor’s DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor’s more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz–300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m{sup −1} was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC

  1. Gain and refractive index dynamics in p-doped InAs quantum dash semiconductor optical amplifiers

    SciTech Connect

    Komolibus, Katarzyna; Piwonski, Tomasz; Joshi, Siddharth; Chimot, Nicolas; Lelarge, Francois; Houlihan, John; Huyet, Guillaume

    2016-07-18

    The ultrafast carrier dynamics in a p-doped dash-in-a-well structure at 1.5 μm is experimentally investigated. An analysis of the timescales related to carrier relaxation and escape processes as well as the “dynamical” linewidth enhancement factor is presented and compared with results obtained from similar un-doped materials. Intentional p-doping of the active region results in an enhancement of the intermediate timescale of the gain dynamics associated with phonon-assisted electron capture and a reduction of the α-factor due to increased differential gain.

  2. Tuning Broadband Microwave Amplifiers

    SciTech Connect

    Alaniz, Gabriel

    2003-09-05

    The PEP-II/DA {Phi} NE/ALS longitudinal feedback systems are complex wide bandwidth systems requiring analog, digital and microwave circuits. The solid-state amplifier is one of the components in the microwave circuit that is required to suppress the coupled bunch instabilities that exist in the PEP-II accelerator. The suppression is achieved by using an antenna as a kicker structure that provides an electric field in order to increase or decrease the energy of particles passing through the structure. The amplifier is made up of sixteen 30 to 35W microstrip GaAs FET modules that are combined to obtain 500W over a bandwidth of 850MHz to 1850MHz. The amplifier malfunctioned causing a reduction in the functionality and power output of the individual GaAs FET modules. The amplifier must be repaired. After repair, the amplifier must be tuned to optimize the gain while maintaining proper power output. The amplifier is tuned using microstrip circuit techniques. A variety of microstrip methods are used to obtain the proper line impedance. The result is a working amplifier that operates efficiently.

  3. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

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

  4. 1.2 MW peak power, all-solid-state picosecond laser with a microchip laser seed and a high gain single-passing bounce geometry amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Chunhua; Shen, Lifeng; Zhao, Zhiliang; Liu, Bin; Jiang, Hongbo; Chen, Jun; Liu, Chong

    2016-11-01

    A semiconductor saturable absorber mirror (SESAM) based passively Q-switched microchip Nd:YVO4 seed laser with pulse duration of 90 ps at repetition rate of 100 kHz is amplified by single-passing a Nd:YVO4 bounce amplifier with varying seed input power from 20 μW to 10 mW. The liquid pure metal greasy thermally conductive material is used to replace the traditional thin indium foil as the thermal contact material for better heat load transfer of the Nd:YVO4 bounce amplifier. Temperature distribution at the pump surface is measured by an infrared imager to compare with the numerically simulated results. A highest single-passing output power of 11.3 W is obtained for 10 mW averaged seed power, achieving a pulse peak power of ~1.25 MW and pulse energy of ~113 μJ. The beam quality is well preserved with M2 ≤1.25. The simple configuration of this bounce laser amplifier made the system flexible, robust and cost-effective, showing attractive potential for further applications.

  5. Ball-milled nano-colloids of rare-earth compounds as liquid gain media for capillary optical amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Patel, Darayas; Blockmon, Avery; Ochieng, Vanesa; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wesley, Dennis; Sarkisov, Sergey S.; Darwish, Abdalla M.; Sarkisov, Avedik S.

    2017-02-01

    Nano-colloids and nano-crystals doped with ions of rare-earth elements have recently attracted a lot of attention in the scientific community due to their potential applications as biomarkers, fluorescent inks, gain media for lasers and optical amplifiers. Many rare-earth doped materials of different compositions, shapes and size distribution have been prepared by different synthetic methods, such as chemical vapor deposition, sol-gel process, micro-emulsion techniques, gas phase condensation methods, hydrothermal methods and laser ablation. In this paper micro-crystalline powder of the rare-earthdoped compound NaYF4:Yb3+, Er3+ was synthesized using a simple wet process followed by baking in open air. Under 980 nm diode laser excitation strong fluorescence in the 100 nm band around 1531-nm peak was observed from the synthesized micro-powder. The micro-powder was pulverized using a ball mill and prepared in the form of nano-colloids in different liquids. The particle size of the obtained nano-colloids was measured using an atomic force microscope and a dynamic light scatterometer. The size of the nano-particles was close to 100-nm. The nano-colloids were utilized as a filling media in capillary optical amplifiers and lasers. The gain of a 7-cm-long capillary optical amplifier (150-micron inner diameter) was as high as 6 dB at 200 mW pump power. The synthesized nano-colloids and the active optical components using them can be potentially used in optical communication, signal processing, optical computing, and other applications.

  6. Polarization Maintaining, Very-Large-Mode Area, Er Fiber Amplifier for High Energy Pulses at 1572.3 nm

    NASA Technical Reports Server (NTRS)

    Nicholoson, J. W.; DeSantolo, A.; Yan, M. F.; Wisk, P.; Mangan, B.; Puc, G.; Yu, A.; Stephen, M.

    2016-01-01

    We demonstrate the first polarization maintaining, very-large-mode-area Er-doped fiber amplifier with 1000 square micron effective area. The amplifier is core pumped by a Raman fiber laser and is used to generate single frequency one microsecond pulses with pulse energy of 368 microJoules, M2 of 1.1, and polarization extinction greater than 20 dB. The amplifier operates at 1572.3 nm, a wavelength useful for trace atmospheric CO2 detection.

  7. Dynamic energy-balance model predicting gestational weight gain

    USDA-ARS?s Scientific Manuscript database

    Gestational weight gains (GWGs) that exceed the 2009 Institute of Medicine recommended ranges increase risk of long-term postpartum weight retention; conversely, GWGs within the recommended ranges are more likely to result in positive maternal and fetal outcomes. Despite this evidence, recent epide...

  8. A dynamic model of metabolizable energy utilization in growing and mature cattle. II. Metabolizable energy utilization for gain.

    PubMed

    Williams, C B; Jenkins, T G

    2003-06-01

    Component models were developed to predict the net efficiency of ME utilization for gain in cattle and to predict daily gain using recovered energy as the input. These models were integrated into a single model to predict daily gain from ME available for gain. One component model predicts the net efficiency of ME utilization for gain using constant partial net efficiencies of 0.2 and 0.75 for ME retention as protein and fat, respectively. This model predicts net efficiency of ME utilization for gain as a function of the ratio of the energy recovered in protein to the total energy recovered. The other component model predicts daily gain as a function of recovered energy and is represented by a system of ordinary differential equations that are numerically integrated on a daily basis. This model was developed by reformulating the equations in a published body composition model that uses daily gain to predict composition of gain since recovered energy is a function of gain and composition of gain. The equations in the two component models interact in that net efficiency is used to predict recovered energy from ME for gain, and in turn, recovered energy is used to predict gain in empty BW, which determines net efficiency through composition of gain. The numeric integration procedure provides an iterative solution for net efficiency. Simulated response of net efficiency for Hereford x Angus steers at 400 kg of empty BW decreased from 0.57 to 0.52 on diets with ME densities of 3.1 and 2.6 Mcal/kg of DM, and restricting the lower-quality diet to 75% of ad libitum intake resulted in a simulated net efficiency of 0.47. These responses in net efficiency were shown to be a result of composition of gain, with leaner gains resulting in lower net efficiencies.

  9. Design of a robust thin-film interference filter for erbium-doped fiber amplifier gain equalization.

    PubMed

    Verly, Pierre G

    2002-06-01

    Gain-flattening filters (GFFs) are key wavelength division multiplexing components in fiber-optics telecommunications. Challenging issues in the design of thin-film GFFs were recently the subject of a contest organized at the 2001 Conference on Optical Interference Coatings. The interest and main difficulty of the proposed problem was to minimize the sensitivity of a GFF to simulated fabrication errors. A high-yield solution and its design philosophy are described. The approach used to control the filter robustness is explained and illustrated by numerical results.

  10. Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Duan, Pengfei; Zhang, Li; Liu, Minghua

    2017-06-01

    Transfer of both chirality and energy information plays an important role in biological systems. Here we show a chiral donor π-gelator and assembled it with an achiral π-acceptor to see how chirality and energy can be transferred in a composite donor-acceptor system. It is found that the individual chiral gelator can self-assemble into nanohelix. In the presence of the achiral acceptor, the self-assembly can also proceed and lead to the formation of the composite nanohelix. In the composite nanohelix, an energy transfer is realized. Interestingly, in the composite nanohelix, the achiral acceptor can both capture the supramolecular chirality and collect the circularly polarized energy from the chiral donor, showing both supramolecular chirality and energy transfer amplified circularly polarized luminescence (ETACPL).

  11. Dietary energy density but not glycemic load is associated with gestational weight gain

    PubMed Central

    Deierlein, Andrea L.; Siega-Riz, Anna Maria; Herring, Amy

    2009-01-01

    Background The majority of pregnant women are gaining outside of the recommended weight gain ranges. Excessive weight gains have been linked to pregnancy complications and long term maternal and child health outcomes. Objective To examine the impact of dietary glycemic load and energy density on total gestational weight gain and weight gain ratio (observed weight gain/expected weight gain). Design Data are from 1231 women with singleton pregnancies who participated in the Pregnancy, Infection, and Nutrition Cohort Study. Dietary information was collected at 26–29 weeks gestation using a semi-quantified food frequency questionnaire. Linear regression models were used to estimate the associations between glycemic load (in quartiles) and energy density (in quartiles) with total gestational weight gain and weight gain ratio. Results Dietary patterns of pregnant women significantly differed across many sociodemographic and behavioral characteristics, with the greatest contrasts seen for glycemic load. After adjustment for covariates, in comparison to women in the first quartile, consuming a mean dietary energy density of 0.77 kcal/g (reference), women in the second quartile, consuming a mean energy density of 0.95 kcal/g, gained an excess of 0.91 kg (95% CI: 0.02–1.79) and women in the third quartile, consuming a mean energy density of 1.09 kcal/g, gained an excess of 1.47 kg (95% CI: 0.58–2.36). All other comparisons of energy intakes were not statistically significant. Glycemic load was not associated with total gestational weight gain or weight gain ratio. Conclusions Dietary energy density is a modifiable factor that may assist pregnant women in managing gestational weight gains. PMID:18779285

  12. Light-Harvesting and Amplified Energy Transfer in Conjugated Polymer Nanoparticles.

    PubMed

    Jiang, Yifei; McNeill, Jason

    2017-01-25

    Conjugated polymer nanoparticles are a class of nanoparticles with many useful and interesting properties, including very high fluorescence brightness, excellent photostability, and sensing capabilities. They also exhibit interesting and potentially useful phenomena, such as highly efficient energy transfer, anomalous single particle blinking, and twinkling phenomena associated with polaron motion. As little as one dye molecule per nanoparticle can efficiently quench the fluorescence of hundreds of polymer chromophore units. Similarly, loss of a single electron can result in quenching of hundreds of chromophores. These phenomena and properties are dictated by the nature of interactions between chromophores in this dense, nanoscale multichromophoric system, and are characterized as amplified energy transfer or multiple energy transfer. In this review, we summarize the key aspects of conjugated polymer nanoparticles optical properties and phenomena, and discuss the current understanding of exciton dynamics in these and related systems. In particular, our current understanding and theoretical models for amplified or multiple energy transfer based on exciton theory and Förster resonance energy transfer are explored.

  13. Design and experimental study of a velocity amplified electromagnetic vibration energy harvester

    NASA Astrophysics Data System (ADS)

    Klein, Jackson A.; Zuo, Lei

    2017-04-01

    Dedicated sensors are widely used throughout many industries to monitor everyday operations, maintain safety and report performance characteristics. In order to adopt a more sustainable solution, intensive research is being conducted for self-powered sensing. To enable sensors to power themselves, harvesting energy from environmental vibration has been widely studied, however, its overall effectiveness remains questionable due to small vibration amplitudes and thus limited harvestable energy density. This paper addresses the issue by proposing a novel vibration energy harvester in which a metal compliant mechanism frame is used to house both a linear electromagnetic generator and proof mass. Due to the compliant mechanism, the proposed energy harvester is capable of amplifying machine vibration velocity for a dedicated electromagnetic generator, largely increasing the energy density. The harvester prototype is also fabricated and experimentally characterized to verify its effectiveness. When operating at its natural frequency in a low base amplitude, 0.001 in (25.4μm) at 19.4 Hz, during lab tests, the harvester has been shown to produce up to 0.91 V AC open voltage, and a maximum power of 2 mW, amplifying the relative proof mass velocity by approximately 5.4 times. In addition, a mathematical model is created based on the pseudo-rigid-body dynamics and the analysis matches closely with experiments. The proposed harvester was designed using vibration data from nuclear power plants. Further steps for improving such a design are given for broader applications.

  14. Electromagnetic energy applied to and gained from lunar materials

    SciTech Connect

    Meek, T.T.; Vaniman, D.T.; Blake, R.D.; Cocks, F.H.

    1986-01-01

    Electromagnetic energy may be useful in microwave frequencies for in-situ melting or sintering of lunar regolith. Simple configurations of magnetron or gyrotron tubes might be constructed for unique melting geometries. For energy production, lunar ilmenite has potential applications in photovoltaic devices. 11 refs., 11 figs.

  15. Efficiency enhancement using electron energy detuning in a laser seeded free electron laser amplifier

    SciTech Connect

    Wang, X. J.; Watanabe, T.; Shen, Y.; Li, R. K.; Murphy, J. B.; Tsang, T.; Freund, H. P.

    2007-10-29

    We report the experimental characterization of efficiency enhancement in a single-pass seeded free-electron laser (FEL) where the electron energy is detuned from resonance. Experiments show a doubling of the efficiency for beam energies above the resonant energy. Measurements of the FEL spectra versus energy detuning shows that the wavelength is governed by the seed laser. The variation in the gain length with beam energy was also observed. Good agreement is found between the experiment and numerical simulations using the MEDUSA simulation code.

  16. A velocity-amplified electromagnetic energy harvester for small amplitude vibration

    NASA Astrophysics Data System (ADS)

    Klein, J.; Zuo, L.

    2017-09-01

    Dedicated, self-powered wireless sensors are widely being studied for use throughout many industries to monitor everyday operations, maintain safety, and report performance characteristics. To enable sensors to power themselves, harvesting energy from machine vibration has been studied, however, its overall effectiveness can be hampered due to small vibration amplitudes and thus limited harvestable energy density. This paper addresses the issue by proposing a novel vibration energy harvester architecture in which a compliant mechanism and proof mass system is used to amplify the vibrational velocity of machine vibration for a linear electromagnetic generator. A prototype has been fabricated and experimentally characterized to verify its effectiveness. When operating at its natural frequency in a low base amplitude, 0.001 inch (25.4 μm) at 19.4 Hz, during lab tests, the harvester has been shown to produce up to 0.91 V AC open voltage, and a maximum power of 2 mW, amplifying the relative proof mass velocity by approximately 5.4 times. This method of locally increasing the machine vibrational velocity has been shown to be a viable option for increasing the potential power output of an energy harvester. In addition, a mathematical model is created based on pseudo-rigid-body dynamics and the analysis matches closely with experiments.

  17. Single crystalline Er{sub 2}O{sub 3}:sapphire films as potentially high-gain amplifiers at telecommunication wavelength

    SciTech Connect

    Kuznetsov, A. S.; Sadofev, S.; Schäfer, P.; Kalusniak, S.; Henneberger, F.

    2014-11-10

    Single crystalline thin films of Er{sub 2}O{sub 3}, demonstrating efficient 1.5 μm luminescence of Er{sup 3+} at room temperature were grown on Al{sub 2}O{sub 3} substrate by molecular beam epitaxy. The absorption coefficient at 1.536 μm was found to reach 270 cm{sup −1} translating in a maximal possible gain of 1390 dBcm{sup −1}. In conjunction with the 10% higher refractive index as compared to Al{sub 2}O{sub 3}, this opens the possibility to use Er{sub 2}O{sub 3}:sapphire films as short-length waveguide amplifiers in telecommunication.

  18. An ultra-low-power pulse oximeter implemented with an energy-efficient transimpedance amplifier.

    PubMed

    Tavakoli, M; Turicchia, L; Sarpeshkar, R

    2010-02-01

    Pulse oximeters are ubiquitous in modern medicine to noninvasively measure the percentage of oxygenated hemoglobin in a patient's blood by comparing the transmission characteristics of red and infrared light-emitting diode light through the patient's finger with a photoreceptor. We present an analog single-chip pulse oximeter with 4.8-mW total power dissipation, which is an order of magnitude below our measurements on commercial implementations. The majority of this power reduction is due to the use of a novel logarithmic transimpedance amplifier with inherent contrast sensitivity, distributed amplification, unilateralization, and automatic loop gain control. The transimpedance amplifier, together with a photodiode current source, form a high-performance photoreceptor with characteristics similar to those found in nature, which allows LED power to be reduced. Therefore, our oximeter is well suited for portable medical applications, such as continuous home-care monitoring for elderly or chronic patients, emergency patient transport, remote soldier monitoring, and wireless medical sensing. Furthermore, our design obviates the need for an A-to-D and digital signal processor and leads to a small single-chip solution. We outline how extensions of our work could lead to submilliwatt oximeters.

  19. Method and system for compact and efficient high energy pulsed laser amplifier

    DOEpatents

    Erlandson, Alvin Charles

    2014-03-11

    An optical amplifier system includes an input aperture operable to receive light propagating along an optical path in a first direction and a first polarizer disposed along the optical path. The first polarizer is operable to pass light having a polarization state aligned with a first polarization axis. The system also includes a first Pockels cell operable to receive light passing through the first polarizer, an optical gain element disposed along the optical path, a second Pockels cell disposed along the optical path, and a second polarizer disposed along the optical path. The second polarizer is operable to pass light having a polarization state aligned with the first polarization axis. The system further includes a first mirror operable to receive light reflected from the second polarizer, a second mirror operable to receive light reflected from the first polarizer, and an output aperture operable to transmit light passing through the second polarizer.

  20. Selection of energy optimized pump concepts for multi core and multi mode erbium doped fiber amplifiers.

    PubMed

    Krummrich, Peter M; Akhtari, Simon

    2014-12-01

    The selection of an appropriate pump concept has a major impact on amplifier cost and power consumption. The energy efficiency of different pump concepts is compared for multi core and multi mode active fibers. In preamplifier stages, pump power density requirements derived from full C-band low noise WDM operation result in superior energy efficiency of direct pumping of individual cores in a multi core fiber with single mode pump lasers compared to cladding pumping with uncooled multi mode lasers. Even better energy efficiency is achieved by direct pumping of the core in multi mode active fibers. Complexity of pump signal combiners for direct pumping of multi core fibers can be reduced by deploying integrated components.

  1. Efficient sub-joule energy extraction from a diode-pumped Nd:LuAG amplifier seeded by a Nd:YAG laser.

    PubMed

    Liu, Qiang; Gong, Mali; Liu, Tinghao; Sui, Zhan; Fu, Xing

    2016-11-15

    We report on a joule-level diode-pumped Nd:YAG-Nd:LuAG hybrid active mirror amplifier chain, producing an output energy of 1.52 J at 10 Hz in a 10 ns Q-switched pulse, while a pulse energy of 623 mJ is extracted from the Nd:LuAG stage, corresponding to an optical-to-optical efficiency of 21.7%. To the best of our knowledge, this is the first demonstration of high-energy nanosecond pulse amplification in a Nd:LuAG laser with extracted pulse energies approaching the joule level. The excellent scaling performance confirms Nd:LuAG as a very promising gain medium for high-energy, short-pulse lasers.

  2. LEAP Phase II, Net Energy Gain From Laser Fields in Vacuum

    SciTech Connect

    Barnes, C.D.; Colby, E.R.; Plettner, T.; /SLAC /Stanford U., Appl. Mech. Dept.

    2005-09-27

    The current Laser Electron Acceleration Program (LEAP) seeks to modulate the energy of an electron bunch by interaction of the electrons with a copropagating pair of crossed laser beams at 800 nm. We present an optical injector design for a LEAP cell so that it can be used to give net energy gain to an electron bunch. Unique features of the design are discussed which will allow this net energy gain and which will also provide a robust signature for the LEAP interaction.

  3. 615 fs pulses with 17 mJ energy generated by an Yb:thin-disk amplifier at 3 kHz repetition rate.

    PubMed

    Fischer, Jonathan; Heinrich, Alexander-Cornelius; Maier, Simon; Jungwirth, Julian; Brida, Daniele; Leitenstorfer, Alfred

    2016-01-15

    A combination of Er/Yb:fiber and Yb:thin-disk technology produces 615 fs pulses at 1030 nm with an average output power of 72 W. The regenerative amplifier allows variation of the repetition rate between 3 and 5 kHz with pulse energies from 13 to 17 mJ. A broadband and intense seed provided by the compact and versatile fiber front-end minimizes gain narrowing. The resulting sub-ps performance is ideal for nonlinear frequency conversion and pulse compression. Operating in the upper branch of a bifurcated pulse train, the system exhibits exceptional noise performance and stability.

  4. Bidirectional amplifier

    DOEpatents

    Wright, James T.

    1986-01-01

    A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

  5. Bidirectional amplifier

    DOEpatents

    Wright, J.T.

    1984-02-02

    A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

  6. LASER BEAMS: Formation of a beam profile at the input to a high-energy laser amplifier

    NASA Astrophysics Data System (ADS)

    Martyanov, M. A.; Poteomkin, A. K.; Shaykin, A. A.; Khazanov, E. A.

    2008-04-01

    A device consisting of a pin-hole line and an apodizing aperture, which provides the fill factor of the laser amplifier aperture equal to 0.8, is proposed and studied experimentally. The use of this device allowed the generation of 300-J, 1-ns pulses due to the efficient energy extraction from a six-stage neodymium phosphate glass amplifier with the final stage aperture equal to 10 cm.

  7. High power regenerative laser amplifier

    DOEpatents

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

    1994-02-08

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  8. High power regenerative laser amplifier

    DOEpatents

    Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.

    1994-01-01

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  9. 18 CFR 11.11 - Energy gains method of determining headwater benefits charges.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... most likely alternative source during the period for which the charge is assessed. ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Energy gains method of... ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL...

  10. 18 CFR 11.11 - Energy gains method of determining headwater benefits charges.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... most likely alternative source during the period for which the charge is assessed. ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Energy gains method of... ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL...

  11. 18 CFR 11.15 - Procedures for determining charges by energy gains investigation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Procedures for determining charges by energy gains investigation. 11.15 Section 11.15 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF THE...

  12. 18 CFR 11.14 - Procedures for establishing charges without an energy gains investigation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Procedures for establishing charges without an energy gains investigation. 11.14 Section 11.14 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF...

  13. 18 CFR 11.11 - Energy gains method of determining headwater benefits charges.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Energy gains method of determining headwater benefits charges. 11.11 Section 11.11 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT ANNUAL CHARGES UNDER PART I OF THE FEDERAL...

  14. High-energy, in-band pumped erbium doped fiber amplifiers.

    PubMed

    Lim, Ee-Leong; Shaif-ul Alam; Richardson, David J

    2012-08-13

    We have demonstrated and compared high-energy, in-band pumped erbium doped fiber amplifiers operating at 1562.5 nm under both a core pumping scheme (CRS) and a cladding pumping scheme (CLS). The CRS/CLS sources generated smooth, single-peak pulses with maximum pulse energies of ~1.53/1.50 mJ, and corresponding pulse widths of ~176/182 ns respectively, with an M2 of ~1.6 in both cases. However, the conversion efficiency for the CLS was >1.5 times higher than the equivalent CRS variant operating at the same pulse energy due to the lower pump intensity in the CLS that mitigates the detrimental effects of ion concentration quenching. With a longer fiber length in a CLS implementation a pulse energy of ~2.6 mJ is demonstrated with a corresponding M2 of ~4.2. Using numerical simulations we explain that the saturation of pulse energy observed in our experiments is due to saturation of the pump absorption.

  15. Progress on diamond amplified photo-cathode

    SciTech Connect

    Wang, E.; Ben-Zvi, I.; Burrill, A.; Kewisch, J.; Chang, X.; Rao, T.; Smedley, J.; Wu, Q.; Muller, E.; Xin, T.

    2011-03-28

    Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length. The diamond-amplified photocathode, that promises to support a high average current, low emittance, and a highly stable electron beam with a long lifetime, is under development for an electron source. The diamond, functioning as a secondary emitter amplifies the primary current, with a few KeV energy, that comes from the traditional cathode. Earlier, our group recorded a maximum gain of 40 in the secondary electron emission from a diamond amplifier. In this article, we detail our optimization of the hydrogenation process for a diamond amplifier that resulted in a stable emission gain of 140. We proved that these characteristics are reproducible. We now are designing a system to test the diamond amplifier cathode using an 112MHz SRF gun to measure the limits of the emission current's density, and on the bunch charge and bunch length.

  16. The influence of mass configurations on velocity amplified vibrational energy harvesters

    NASA Astrophysics Data System (ADS)

    O'Donoghue, D.; Frizzell, R.; Kelly, G.; Nolan, K.; Punch, J.

    2016-05-01

    Vibrational energy harvesters scavenge ambient vibrational energy, offering an alternative to batteries for the autonomous operation of low power electronics. Velocity amplified electromagnetic generators (VAEGs) utilize the velocity amplification effect to increase power output and operational bandwidth, compared to linear resonators. A detailed experimental analysis of the influence of mass ratio and number of degrees-of-freedom (dofs) on the dynamic behaviour and power output of a macro-scale VAEG is presented. Various mass configurations are tested under drop-test and sinusoidal forced excitation, and the system performances are compared. For the drop-test, increasing mass ratio and number of dofs increases velocity amplification. Under forced excitation, the impacts between the masses are more complex, inducing greater energy losses. This results in the 2-dof systems achieving the highest velocities and, hence, highest output voltages. With fixed transducer size, higher mass ratios achieve higher voltage output due to the superior velocity amplification. Changing the magnet size to a fixed percentage of the final mass showed the increase in velocity of the systems with higher mass ratios is not significant enough to overcome the reduction in transducer size. Consequently, the 3:1 mass ratio systems achieved the highest output voltage. These findings are significant for the design of future reduced-scale VAEGs.

  17. Energy expenditure, spontaneous physical activity and with weight gain in kidney transplant recipients.

    PubMed

    Heng, Anne-Elisabeth; Montaurier, Christophe; Cano, Noël; Caillot, Nicolas; Blot, A; Meunier, Nathalie; Pereira, Bruno; Marceau, Geoffroy; Sapin, Vincent; Jouve, Christelle; Boirie, Yves; Deteix, Patrice; Morio, Beatrice

    2015-06-01

    Alterations in energy metabolism could trigger weight gain after renal transplantation. Nineteen transplanted non-diabetic men, 53 ± 1.6 years old, receiving calcineurin inhibitors but no corticosteroids were studied. They were compared with nine healthy men matched for height, age and lean body mass. Daily energy expenditure and its components (sleeping, basal and absorptive metabolic rates) were analyzed for 24 h in calorimetric chambers and for 4 days in free living conditions using calibrated accelerometry. Other variables known to influence energy expenditure were assessed: body composition, physical activity, 4-day food intake, drug consumption, serum C-reactive protein, interleukin-6, thyroid and parathyroid hormones, and epinephrine. Transplant recipients who gained more than 5% body weight after transplantation (n = 11, +11.0 ± 1.5 kg) were compared with those who did not (n = 8) and with the controls. Weight gain compared with non-weight gain patients and controls exhibited higher fat mass without change in lean body mass. Daily, sleeping and resting energy expenditure adjusted for lean body mass was significantly higher in non-weight gain (167.1 ± 4.2 kJ/kg/lean body mass/24 h, P < 0.05) compared with weight gain patients (147.4 ± 3.6) and controls (146.1 ± 4.6). Weight gain compared with controls and non-weight gain subjects had lower free living physical activity and a higher consumption of antihypertensive drugs and β-blockers. After kidney transplantation, weight gain patients were characterized by lower adjusted energy expenditure, reduced spontaneous physical activity but a more sedentary life style and a trend toward a higher energy intake explaining the reason they gained weight. The nWG KTR had increased resting and sleeping EE which protected them from weight gain. Such hypermetabolism was also observed in 24-h EE measurements. By comparison with the nWG patients, the WG transplant recipients were characterized by higher

  18. Amplifying Real Estate Value through Energy&WaterManagement: From ESCO to 'Energy Services Partner'

    SciTech Connect

    Mills, Evan

    2004-06-08

    The energy service company (ESCO) business model could become significantly more effective by integrating the energy-efficiency purveyor and their capital into the underlying building ownership and operation partnership, rather than the current model in which the ESCO remains an outsider with higher transaction costs and limited interest and participation in the value created by the cost savings. Resource conservation advocates rarely use the language of real estate to articulate the cost effectiveness of capital improvements aimed at reducing utility costs in commercial and residential income properties. Conventional methods that rely on rarefied academic notions of simple payback time or a narrow definition of return on investment fail to capture a significant component of the true market value created by virtue of reduced operating expenses. Improvements in energy and water efficiency can increase the fundamental profitability of real estate investments by raising Net Operating Income (NOI), and hence returns during the holding period, and, ultimately, proceeds at time of sale. We introduce the concept of an Energy Services Partner, who takes an equity interest in a real estate partnership in exchange for providing the expertise and capital required to reduce utility operating costs. Profit to all partners increases considerably as a result. This approach would also help to address a crisis facing ESCOs today stemming from their considerable liabilities (through guaranteed savings) and negligible offsetting assets.

  19. Cooking increases net energy gain from a lipid-rich food

    PubMed Central

    Groopman, Emily E.; Carmody, Rachel N.; Wrangham, Richard W.

    2014-01-01

    Starch, protein, and lipid are three major sources of calories in the human diet. The unique and universal human practice of cooking has been demonstrated to increase the energy gained from foods rich in starch or protein. Yet no studies have tested whether cooking has equivalent effects on the energy gained from lipid-rich foods. Using mice as a model, we addressed this question by examining the impact of cooking on the energy gained from peanuts, a lipid-rich oilseed, and compared this impact against that of nonthermal processing (blending). We found that cooking consistently increased the energy gained per calorie, whereas blending had no detectable energetic benefits. Assessment of fecal fat excretion showed increases in lipid digestibility when peanuts were cooked, and examination of diet microstructure revealed concomitant alterations to the integrity of cell walls and the oleosin layer of proteins that otherwise shield lipids from digestive lipases. Both effects were consistent with the greater energy gain observed with cooking. Our findings highlight the importance of cooking in increasing dietary energy returns for humans, both past and present. PMID:25293786

  20. Cooking increases net energy gain from a lipid-rich food.

    PubMed

    Groopman, Emily E; Carmody, Rachel N; Wrangham, Richard W

    2015-01-01

    Starch, protein, and lipid are three major sources of calories in the human diet. The unique and universal human practice of cooking has been demonstrated to increase the energy gained from foods rich in starch or protein. Yet no studies have tested whether cooking has equivalent effects on the energy gained from lipid-rich foods. Using mice as a model, we addressed this question by examining the impact of cooking on the energy gained from peanuts, a lipid-rich oilseed, and compared this impact against that of nonthermal processing (blending). We found that cooking consistently increased the energy gained per calorie, whereas blending had no detectable energetic benefits. Assessment of fecal fat excretion showed increases in lipid digestibility when peanuts were cooked, and examination of diet microstructure revealed concomitant alterations to the integrity of cell walls and the oleosin layer of proteins that otherwise shield lipids from digestive lipases. Both effects were consistent with the greater energy gain observed with cooking. Our findings highlight the importance of cooking in increasing dietary energy returns for humans, both past and present.

  1. Design and implementation of a wireless (Bluetooth) four channel bio-instrumentation amplifier and digital data acquisition device with user-selectable gain, frequency, and driven reference.

    PubMed

    Cosmanescu, Alin; Miller, Benjamin; Magno, Terence; Ahmed, Assad; Kremenic, Ian

    2006-01-01

    A portable, multi-purpose Bio-instrumentation Amplifier and Data AcQuisition device (BADAQ) capable of measuring and transmitting EMG and EKG signals wirelessly via Bluetooth is designed and implemented. Common topologies for instrumentation amplifiers and filters are used and realized with commercially available, low-voltage, high precision operational amplifiers. An 8-bit PIC microcontroller performs 10-bit analog-to-digital conversion of the amplified and filtered signals and controls a Bluetooth transceiver capable of wirelessly transmitting the data to any Bluetooth enabled device. Electrical isolation between patient/subject, circuitry, and ancillary equipment is achieved by optocoupling components. The design focuses on simplicity, portability, and affordability.

  2. Variations in resting energy expenditure: impact on gestational weight gain.

    PubMed

    Berggren, E K; O'Tierney-Ginn, P; Lewis, S; Presley, L; De-Mouzon, S Hauguel; Catalano, P M

    2017-10-01

    There are significant variations in gestational weight gain, with many women gaining in excess of the Institute of Medicine guidelines. Unfortunately, efforts to improve appropriate gestational weight gain have had only limited success. To date, interventions have focused primarily on decreasing energy intake and/or increasing physical activity. Maternal resting energy expenditure, which comprises ∼60% of total energy expenditure compared with the ∼20% that comes from physical activity, may be an important consideration in understanding variations in gestational weight gain. Our objective was to quantify the changes in resting energy expenditure during pregnancy and their relationship to gestational weight gain and body composition changes among healthy women. We hypothesized that greater gestational weight gain, and fat mass accrual in particular, are inversely related to variations in resting energy expenditure. We conducted a secondary analysis of a prospective cohort studied before conception and late pregnancy (34-36 weeks). Body composition (estimated using hydrodensitometry) and resting energy expenditure (estimated using indirect calorimetry) were measured. The relationship between the changes in resting energy expenditure and gestational weight gain and the change in fat mass and fat-free mass were quantified. Resting energy expenditure was expressed as kilocalories per kilogram of fat-free mass per day (kilocalories per kilogram of fat-free mass(-1)/day(-1)) and kilocalories per day. Correlations are reported as r. Among 51 women, preconception body mass index was 23.0 (4.7) kg/m(2); gestational weight gain was 12.8 (4.7) kg. Preconception and late pregnancy resting energy expenditure (kilocalories per day) correlated positively with the change in fat-free mass (r = 0.37, P = .008; r = 0.51, P = .001). Late-pregnancy resting energy expenditure (kilocalories per kilogram of fat-free mass(-1)/day(-1)) was inversely associated with the change in fat

  3. Amplified total internal reflection.

    PubMed

    Fan, J; Dogariu, A; Wang, L J

    2003-02-24

    Totally internal reflected beams can be amplified if the lowerindex medium has gain. We analyze the reflection and refraction of light, and analytically derive the expression for the Goos-Hänchen shifts of a Gaussian beam incident on a lower-index medium, both active and absorptive. We examine the energy flow and the Goos-Hänchen shifts for various cases. The analytical results are consistent with the numerical results. For the TE mode, the Goos-Hänchen shift for the transmitted beam is exactly half of that of the reflected beam, resulting in a "1/2" rule.

  4. High energy gain in three-dimensional simulations of light sail acceleration

    SciTech Connect

    Sgattoni, A.; Sinigardi, S.; Macchi, A.

    2014-08-25

    The dynamics of radiation pressure acceleration in the relativistic light sail regime are analysed by means of large scale, three-dimensional (3D) particle-in-cell simulations. Differently to other mechanisms, the 3D dynamics leads to faster and higher energy gain than in 1D or 2D geometry. This effect is caused by the local decrease of the target density due to transverse expansion leading to a “lighter sail.” However, the rarefaction of the target leads to an earlier transition to transparency limiting the energy gain. A transverse instability leads to a structured and inhomogeneous ion distribution.

  5. Impact of Energy Gain and Subsystem Characteristics on Fusion Propulsion Performance

    NASA Technical Reports Server (NTRS)

    Chakrabarti, S.; Schmidt, G. R.

    2001-01-01

    Rapid transport of large payloads and human crews throughout the solar system requires propulsion systems having very high specific impulse (I(sub sp) > 10(exp 4) to 10(exp 5) s). It also calls for systems with extremely low mass-power ratios (alpha < 10(exp -1) kg/kW). Such low alpha are beyond the reach of conventional power-limited propulsion, but may be attainable with fusion and other nuclear concepts that produce energy within the propellant. The magnitude of energy gain must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive energy-intensive subsystems associated with these concepts. This paper evaluates the impact of energy gain and subsystem characteristics on alpha. Central to the analysis are general parameters that embody the essential features of any 'gain-limited' propulsion power balance. Results show that the gains required to achieve alpha = 10(exp -1) kg/kW with foreseeable technology range from approximately 100 to over 2000, which is three to five orders of magnitude greater than current fusion state of the arL Sensitivity analyses point to the parameters exerting the most influence for either: (1) lowering a and improving mission performance or (2) relaxing gain requirements and reducing demands on the fusion process. The greatest impact comes from reducing mass and increasing efficiency of the thruster and subsystems downstream of the fusion process. High relative gain, through enhanced fusion processes or more efficient drivers and processors, is also desirable. There is a benefit in improving driver and subsystem characteristics upstream of the fusion process, but it diminishes at relative gains > 100.

  6. Impact of Energy Gain and Subsystem Characteristics on Fusion Propulsion Performance

    NASA Technical Reports Server (NTRS)

    Chakrabarti, S.; Schmidt, G. R.

    2001-01-01

    Rapid transport of large payloads and human crews throughout the solar system requires propulsion systems having very high specific impulse (I(sub sp) > 10(exp 4) to 10(exp 5) s). It also calls for systems with extremely low mass-power ratios (alpha < 10(exp -1) kg/kW). Such low alpha are beyond the reach of conventional power-limited propulsion, but may be attainable with fusion and other nuclear concepts that produce energy within the propellant. The magnitude of energy gain must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive energy-intensive subsystems associated with these concepts. This paper evaluates the impact of energy gain and subsystem characteristics on alpha. Central to the analysis are general parameters that embody the essential features of any 'gain-limited' propulsion power balance. Results show that the gains required to achieve alpha = 10(exp -1) kg/kW with foreseeable technology range from approximately 100 to over 2000, which is three to five orders of magnitude greater than current fusion state of the arL Sensitivity analyses point to the parameters exerting the most influence for either: (1) lowering a and improving mission performance or (2) relaxing gain requirements and reducing demands on the fusion process. The greatest impact comes from reducing mass and increasing efficiency of the thruster and subsystems downstream of the fusion process. High relative gain, through enhanced fusion processes or more efficient drivers and processors, is also desirable. There is a benefit in improving driver and subsystem characteristics upstream of the fusion process, but it diminishes at relative gains > 100.

  7. Segmented amplifier configurations for laser amplifier

    DOEpatents

    Hagen, Wilhelm F.

    1979-01-01

    An amplifier system for high power lasers, the system comprising a compact array of segments which (1) preserves high, large signal gain with improved pumping efficiency and (2) allows the total amplifier length to be shortened by as much as one order of magnitude. The system uses a three dimensional array of segments, with the plane of each segment being oriented at substantially the amplifier medium Brewster angle relative to the incident laser beam and with one or more linear arrays of flashlamps positioned between adjacent rows of amplifier segments, with the plane of the linear array of flashlamps being substantially parallel to the beam propagation direction.

  8. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  9. Diode amplifier of modulated optical beam power

    SciTech Connect

    D'yachkov, N V; Bogatov, A P; Gushchik, T I; Drakin, A E

    2014-11-30

    Analytical relations are obtained between characteristics of modulated light at the output and input of an optical diode power amplifier operating in the highly saturated gain regime. It is shown that a diode amplifier may act as an amplitude-to-phase modulation converter with a rather large bandwidth (∼10 GHz). The low sensitivity of the output power of the amplifier to the input beam power and its high energy efficiency allow it to be used as a building block of a high-power multielement laser system with coherent summation of a large number of optical beams. (lasers)

  10. Unlimited energy gain in the laser-driven radiation pressure dominant acceleration of ions

    SciTech Connect

    Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Echkina, E. Yu.; Inovenkov, I. N.; Pegoraro, F.; Korn, G.

    2010-06-15

    The energy of the ions accelerated by an intense electromagnetic wave in the radiation pressure dominated regime can be greatly enhanced by a transverse expansion of a thin target. The expansion decreases the number of accelerated ions in the irradiated region increasing the energy and the longitudinal velocity of the remaining ions. In the relativistic limit, the ions become phase locked with respect to the electromagnetic wave resulting in an unlimited ion energy gain. This effect and the use of optimal laser pulse shape provide a new approach for greatly enhancing the energy of laser accelerated ions.

  11. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    PubMed

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  12. Self-amplified spontaneous emission for a single pass free-electron laser

    NASA Astrophysics Data System (ADS)

    Giannessi, L.; Alesini, D.; Antici, P.; Bacci, A.; Bellaveglia, M.; Boni, R.; Boscolo, M.; Briquez, F.; Castellano, M.; Catani, L.; Chiadroni, E.; Cianchi, A.; Ciocci, F.; Clozza, A.; Couprie, M. E.; Cultrera, L.; Dattoli, G.; Del Franco, M.; Dipace, A.; di Pirro, G.; Doria, A.; Drago, A.; Fawley, W. M.; Ferrario, M.; Ficcadenti, L.; Filippetto, D.; Frassetto, F.; Freund, H. P.; Fusco, V.; Gallerano, G.; Gallo, A.; Gatti, G.; Ghigo, A.; Giovenale, E.; Marinelli, A.; Labat, M.; Marchetti, B.; Marcus, G.; Marrelli, C.; Mattioli, M.; Migliorati, M.; Moreno, M.; Mostacci, A.; Orlandi, G.; Pace, E.; Palumbo, L.; Petralia, A.; Petrarca, M.; Petrillo, V.; Poletto, L.; Quattromini, M.; Rau, J. V.; Reiche, S.; Ronsivalle, C.; Rosenzweig, J.; Rossi, A. R.; Rossi Albertini, V.; Sabia, E.; Serafini, L.; Serluca, M.; Spassovsky, I.; Spataro, B.; Surrenti, V.; Vaccarezza, C.; Vescovi, M.; Vicario, C.

    2011-06-01

    SPARC (acronym of “Sorgente Pulsata ed Amplificata di Radiazione Coerente”, i.e. Pulsed and Amplified Source of Coherent Radiation) is a single pass free-electron laser designed to obtain high gain amplification at a radiation wavelength of 500 nm. Self-amplified spontaneous emission has been observed driving the amplifier with the high-brightness beam of the SPARC linac. We report measurements of energy, spectra, and exponential gain. Experimental results are compared with simulations from several numerical codes.

  13. The Physics of Advanced High-Gain Targets for Inertial Fusion Energy

    NASA Astrophysics Data System (ADS)

    Perkins, L. John

    2010-11-01

    In ca. 2011-2012, the National Ignition Facility is poised to demonstrate fusion ignition and gain in the laboratory for the first time. This key milestone in the development of inertial confinement fusion (ICF) can be expected to engender interest in the development of inertial fusion energy (IFE) and expanded efforts on a number of advanced targets that may achieve high fusion energy gain at lower driver energies. In this tutorial talk, we will discuss the physics underlying ICF ignition and thermonuclear burn, examine the requirements for high gain, and outline candidate R&D programs that will be required to assess the performance of these target concepts under various driver systems including lasers, heavy-ions and pulsed power. Such target concepts include those operating by fast ignition, shock ignition, impact ignition, dual-density, magnetically-insulated, one- and two-sided drive, etc., some of which may have potential to burn advanced, non-DT fusion fuels. We will then delineate the role of such targets in their application to the production of high average fusion power. Here, systems studies of IFE economics suggest that we should strive for target fusion gains of around 100 at drive energies of 1MJ, together with corresponding rep-rates of up to 10Hz and driver electrical efficiencies around 15%. In future years, there may be exciting opportunities to study such ``innovative confinement concepts'' with prospects of fielding them on facilities such as NIF to obtain high fusion energy gains on a single shot basis.

  14. Effect of sow parity and weight at service on target maternal weight and energy for gain in gestation.

    PubMed

    Young, M G; Tokach, M D; Aherne, F X; Main, R G; Dritz, S S; Goodband, R D; Nelssen, J L

    2005-01-01

    The objective of this study was to evaluate targeted maternal weight gains in sows by parity group during gestation. Weight and backfat gains during gestation by parity, weight, and backfat groups also were analyzed. The data evaluated were a subset (374 sows) of a larger experiment that compared three methods of feeding sows during gestation on weight and backfat gains and subsequent reproductive performance. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Actual backfat gain for gilts and sows was regressed on maternal weight gain and estimated energy available for gain. The regression equations were then used to predict maternal weight gains for target backfat gains for three parity groups (gilts, Parity 1 and 2 sows, and Parity 3 and older sows). For gilts and Parity 1 and 2 sows, much greater target maternal weight gains are required to achieve 6 and 9 mm of backfat gain, whereas Parity 3 and older sows require maternal weight gains similar to those targeted to achieve the desired backfat gain. Given similar energy intake levels above maintenance, gilts gained more weight than multiparous sows, as gain was based more on protein and less on fat and thus was more efficient. Gilts required more maternal weight gain than sows to achieve similar backfat gains due to the higher protein and low fat contents of gain in younger, lighter sows compared with older parity sows. Low-backfat sows that needed to gain large amounts of backfat failed to achieve these large gains. We speculate this failure may be due to lower tissue insulation levels with the low backfat levels and higher activity levels of these sows compared with high-backfat sows. It seems that both parity and weight are individually important factors that influence energy and nutrient requirements for gestation in the modern sow.

  15. Switchable dual-wavelength single-longitudinal-mode erbium-doped fiber laser using an inverse-Gaussian apodized fiber Bragg grating filter and a low-gain semiconductor optical amplifier.

    PubMed

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Hao, Jianzhong; Dong, Bo; Liang, Sheng

    2010-12-20

    We present a stable and switchable dual-wavelength erbium-doped fiber laser. In the ring cavity, an inverse-Gaussian apodized fiber Bragg grating serves as an ultranarrow dual-wavelength passband filter, a semiconductor optical amplifier biased in the low-gain regime reduces the gain competition of the two wavelengths, and a feedback fiber loop acts as a mode filter to guarantee a stable single-longitudinal-mode operation. Two lasing lines with a wavelength separation of approximately 0.1 nm are obtained experimentally. A microwave signal at 12.51 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  16. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    SciTech Connect

    Litos, M.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Corde, S.; Clayton, C. E.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Schmeltz, M.; Vafaei-Najafabadi, N.; Yakimenko, V.

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gain results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.

  17. Effect of the upper limbs muscles activity on the mechanical energy gain in pole vaulting.

    PubMed

    Frère, Julien; Göpfert, Beat; Slawinski, Jean; Tourny-chollet, Claire

    2012-04-01

    The shoulder muscles are highly solicited in pole vaulting and may afford energy gain. The objective of this study was to determine the bilateral muscle activity of the upper-limbs to explain the actions performed by the vaulter to bend the pole and store elastic energy. Seven experienced athletes performed 5-10 vaults which were recorded using two video cameras (50Hz). The mechanical energy of the centre of gravity (CG) was computed, while surface electromyographic (EMG) profiles were recorded from 5 muscles bilateral: deltoideus, infraspinatus, biceps brachii, triceps, and latissimus dorsi muscles. The level of intensity from EMG profile was retained in four sub phases between take-off (TO1) and complete pole straightening (PS). The athletes had a mean mechanical energy gain of 22% throughout the pole vault, while the intensities of deltoideus, biceps brachii, and latissimus dorsi muscles were sub phases-dependent (p<0.05). Stabilizing the glenohumeral joint (increase of deltoideus and biceps brachii activity) and applying a pole bending torque (increase of latissimus dorsi activity) required specific muscle activation. The gain in mechanical energy of the vaulter could be linked to an increase in muscle activation, especially from latissimusdorsi muscles. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. High-Gradient High-Energy-Gain Inverse Free Electron Laser Experiment Using a Helical Undulator

    NASA Astrophysics Data System (ADS)

    Musumeci, P.; Westfall, M.; Li, R. K.; Murokh, A.; Tremaine, A.; Pogorelsky, I. V.

    2010-11-01

    In this paper we present the design of the high-gradient, high-energy-gain IFEL accelerator proposed for construction at the ATF beamline in BNL. We plan to accelerate the ATF electron beam from 50 MeV to 120 MeV using a 60 cm long tapered permanent magnet helical undulator designed at UCLA and the existing ATF 0.5 TW CO2 laser system. The experiment will obtain a record 120 MV/m gradient and >70 MeV energy gain and will be an important step in the development of compact IFEL accelerators for the mid-high energy range (up to 1-2 GeV).

  19. Route to high-energy dissipative soliton resonance pulse in a dual amplifier figure-of-eight fiber laser

    NASA Astrophysics Data System (ADS)

    Salhi, M.; Semaan, G.; Ben Braham, F.; Fourmont, J.; Bahloul, F.; Sanchez, F.

    2017-05-01

    We present a widely adjustable high energy square pulse laser operating in DSR in a passively mode-locked F8L using dual Er:Yb co-doped double clad amplifiers. By manually controlling the power of each amplifier, the pulse width can be varied in a range of 360 ns without generating multi-pulsing instabilities. To ensure that DSR would dominate the modelocking mechanism, we use a 1.5 km standard single-mode fiber in the cavity. At a maximum pumping power, the laser generated square pulses with 416 ns duration and an average output power of about 1.33 W with a repetition frequency of 133 KHz corresponding to a record pulse energy of 10 μJ.

  20. Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain.

    PubMed

    Markwald, Rachel R; Melanson, Edward L; Smith, Mark R; Higgins, Janine; Perreault, Leigh; Eckel, Robert H; Wright, Kenneth P

    2013-04-02

    Insufficient sleep is associated with obesity, yet little is known about how repeated nights of insufficient sleep influence energy expenditure and balance. We studied 16 adults in a 14- to 15-d-long inpatient study and quantified effects of 5 d of insufficient sleep, equivalent to a work week, on energy expenditure and energy intake compared with adequate sleep. We found that insufficient sleep increased total daily energy expenditure by ∼5%; however, energy intake--especially at night after dinner--was in excess of energy needed to maintain energy balance. Insufficient sleep led to 0.82 ± 0.47 kg (±SD) weight gain despite changes in hunger and satiety hormones ghrelin and leptin, and peptide YY, which signaled excess energy stores. Insufficient sleep delayed circadian melatonin phase and also led to an earlier circadian phase of wake time. Sex differences showed women, not men, maintained weight during adequate sleep, whereas insufficient sleep reduced dietary restraint and led to weight gain in women. Our findings suggest that increased food intake during insufficient sleep is a physiological adaptation to provide energy needed to sustain additional wakefulness; yet when food is easily accessible, intake surpasses that needed. We also found that transitioning from an insufficient to adequate/recovery sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to -0.03 ± 0.50 kg weight loss. These findings provide evidence that sleep plays a key role in energy metabolism. Importantly, they demonstrate physiological and behavioral mechanisms by which insufficient sleep may contribute to overweight and obesity.

  1. Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

    PubMed Central

    Markwald, Rachel R.; Melanson, Edward L.; Smith, Mark R.; Higgins, Janine; Perreault, Leigh; Eckel, Robert H.; Wright, Kenneth P.

    2013-01-01

    Insufficient sleep is associated with obesity, yet little is known about how repeated nights of insufficient sleep influence energy expenditure and balance. We studied 16 adults in a 14- to 15-d-long inpatient study and quantified effects of 5 d of insufficient sleep, equivalent to a work week, on energy expenditure and energy intake compared with adequate sleep. We found that insufficient sleep increased total daily energy expenditure by ∼5%; however, energy intake—especially at night after dinner—was in excess of energy needed to maintain energy balance. Insufficient sleep led to 0.82 ± 0.47 kg (±SD) weight gain despite changes in hunger and satiety hormones ghrelin and leptin, and peptide YY, which signaled excess energy stores. Insufficient sleep delayed circadian melatonin phase and also led to an earlier circadian phase of wake time. Sex differences showed women, not men, maintained weight during adequate sleep, whereas insufficient sleep reduced dietary restraint and led to weight gain in women. Our findings suggest that increased food intake during insufficient sleep is a physiological adaptation to provide energy needed to sustain additional wakefulness; yet when food is easily accessible, intake surpasses that needed. We also found that transitioning from an insufficient to adequate/recovery sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to −0.03 ± 0.50 kg weight loss. These findings provide evidence that sleep plays a key role in energy metabolism. Importantly, they demonstrate physiological and behavioral mechanisms by which insufficient sleep may contribute to overweight and obesity. PMID:23479616

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

    PubMed

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

    2011-03-14

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

  3. Fasting Hyperglycemia Predicts Lower Rates of Weight Gain by Increased Energy Expenditure and Fat Oxidation Rate

    PubMed Central

    Thearle, Marie S.; Bogardus, Clifton; Krakoff, Jonathan

    2015-01-01

    Context: Increased adiposity and insulin resistance are associated with hyperglycemia and previous studies have reported that higher glucoses are associated with lower rates of weight gain. One possible mechanism is via increased energy expenditure (EE). Objective: To assess the relationships between changes in EE during spontaneous weight gain and concomitant changes in glucose levels. Design and Participants: Body composition, metabolic, and glycemic data were available from nondiabetic Native Americans who underwent two measurements of 24-h EE during eucaloric feeding in a metabolic chamber (N = 144; time between measurements: 5.0 ± 3.3 years) or resting EE by ventilated hood system during the euglycemic-hyperinsulinemic clamp (N = 261; 4.5 ± 3.2 years). Long-term follow-up data (8.3 ± 4.3 years) for weight and body composition were available in 131 and 122 subjects, respectively. Main Outcome Measures: Twenty four hour EE and respiratory quotient (RQ), resting (RMR), and sleeping (SMR) metabolic rates, glucose, and insulin levels, basal glucose output (BGO). Results: Weight gain-associated increase in fasting plasma glucose (FPG) levels was accompanied with decreased 24-h RQ (partial R = −0.24, P = .002) and increased 24-h EE, RMR, SMR, and fat oxidation after accounting for changes in body composition (partial R: 0.12 to 0.19, all P ≤ .05). Upon weight gain, BGO tended to increase (P = .07), while insulin infusion induced a decrease in EE (P = .04). Higher baseline FPG predicted lower rates of future weight gain (partial R = −0.18, P = .04). Conclusions: Higher FPG after weight gain was associated with greater-than-expected increase in EE. The rise in BGO and the insulin-induced EE suppression at follow-up indicate that increased hepatic gluconeogenesis may be an important mediator of EE changes associated with weight gain. PMID:25559400

  4. Impact of Energy Gain and Subsystem Characteristics on Fusion Propulsion Performance Balances

    NASA Technical Reports Server (NTRS)

    Chakrabarti, Suman; Schmidt, George R.

    2000-01-01

    Rapid transportation of large payloads and human crews to destinations throughout the solar system will require propulsion systems having not only very high exhaust velocities (I (sub sp) greater than or equal to 10 (exp 4) to 10 (exp 5) sec) but also extremely low mass-power ratios (alpha less than or equal to 10 (exp -1) kg/kW). Such low a are difficult to achieve with power-limited propulsion systems. but may be attainable with fusion and other high I (sub SP) nuclear concepts that produce energy within the propellant. The magnitude of this energy gain is of fundamental importance. It must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive power-intensive subsystems associated with these types of concepts. This paper evaluates the energy gain and mass-power characteristics required for a consistent with 1-year roundtrip planetary missions ranging up to 100 AU. Central to this analysis is an equation for overall system a, which is derived from the power balance of a generalized "gain-limited" propulsion system. Results show that the gain required to achieve alpha approximately 10 (exp -1) kg/kW with foreseeable subsystem technology can vary from 50 to as high as 10,000, which is 2 to 5 orders of magnitude greater than current state-of-the art. However, order of magnitude improvements in propulsion subsystem mass and efficiency could reduce gain requirements to 10 to 1,000 - still a very challenging goal.

  5. Theory of highly charged ion energy gain spectroscopy of molecular collective excitations

    NASA Astrophysics Data System (ADS)

    Lucas, A. A.; Benedek, G.; Sunjic, M.; Echenique, P. M.

    2011-01-01

    This paper discusses the physical mechanism by which a highly charged, energetic ion partly neutralized by electron transfers from a target—a large molecule, a cluster or a solid surface—can create target collective excitations in the process. We develop an analysis for the system of a highly charged ion flying by a fullerene molecule. Our analysis offers a new explanation for the periodic oscillations observed in the high-resolution energy gain spectra of energetic Arq+ ions (q=8, 13, 14, 15) flying by C60 molecules. For the Arq+→Ar(q-s)+ spectra with q=13-15 and s=1 or 2, the observed oscillations of 6 eV periodicity are assigned to energy losses due to multiple, Poissonian excitations of C60 π-plasmons (6 eV quantum). The excitation energy quanta are subtracted from the kinetic energy gained by the ion when one or at most two electrons are transferred to increasingly deep Rydberg states of the ion. The observed 3 eV periodicity for q=8 arises from the specific Rydberg energy levels of ArVIII (Ar7+). The first few shallow levels of this ion are separated by about 3 eV, while some of the pairs of adjacent, deeper levels are also separated by 3 eV. Each deep-level pair produces two interdigitated, Poissonian series of 6 eV π-plasmon excitation peaks resulting in an apparent periodicity of 3 eV throughout the spectra. The broad σ-plasmons (25 eV quantum) are found to contribute a background continuum to the medium- and high-energy regions of the observed spectra. The physical model analyzed here indicates that electronic collective excitations in several other systems could be studied by highly charged ion energy gain spectroscopy at sufficient resolution.

  6. Energy Gain in Collisions of Highly Charged Ions with C_60

    NASA Astrophysics Data System (ADS)

    Thumm, Uwe; Bárány, Anders; Cederquist, Henrik

    1997-04-01

    Within the dynamical classical over--barrier model for charge transfer in soft ion--cluster collisions [1], we have simulated [2] the kinetic energy gain Q of 3.3 q keV Ar^q+ ions in collisions with neutral C_60 targets. Our semi--classical theory allows for the calculation of Q in two different ways, either as difference of electronic binding energies before and after the collision or by integrating the dynamically changing force between the collision partners along the trajectory. A comparison between the two ways provides an intrinsic test of the model calculation. Comparison with recent experimental data [3] shows good agreement in the main features of the energy gain spectra and facilitates their interpretation in terms of the number and final states of transferred electrons. [1] U. Thumm, J. Phys. B27 3515 (1994); Phys. Rev. A55 (Jan.1997). [2] U. Thumm, A. Bárány and H. Cederquist, to be published. [3] N. Selberg et al., Phys. Rev. A 53, 874 (1996). description U.T. is supported by the Division of Chemical Sciences, Basis Energy Sciences, Office of Energy Research, U.S. Department of Energy.

  7. Differential Amplifier with Current-Mirror Load: Influence of Current Gain, Early Voltage, and Supply Voltage on the DC Output Voltage

    ERIC Educational Resources Information Center

    Paulik, G. F.; Mayer, R. P.

    2012-01-01

    A differential amplifier composed of an emitter-coupled pair is useful as an example in lecture presentations and laboratory experiments in electronic circuit analysis courses. However, in an active circuit with zero input load V[subscript id], both laboratory measurements and PSPICE and LTspice simulation results for the output voltage…

  8. Differential Amplifier with Current-Mirror Load: Influence of Current Gain, Early Voltage, and Supply Voltage on the DC Output Voltage

    ERIC Educational Resources Information Center

    Paulik, G. F.; Mayer, R. P.

    2012-01-01

    A differential amplifier composed of an emitter-coupled pair is useful as an example in lecture presentations and laboratory experiments in electronic circuit analysis courses. However, in an active circuit with zero input load V[subscript id], both laboratory measurements and PSPICE and LTspice simulation results for the output voltage…

  9. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    NASA Astrophysics Data System (ADS)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

  10. Burst-mode gain switched technique for high peak and average optical energy extraction.

    PubMed

    Nikumb, S K; Seguin, H J; Seguin, V A; Willis, R J; Cheng, Z; Reshef, H

    1989-05-01

    The optical performance of a cw PIE CO(2) laser has been substantially improved through the adoption of a burst-mode gain switching technique. The approach has provided a doubling of the average beam power extractable from the device. With appropriate optimization, the process could possibly permit the attainment of pulsed energy extraction in the kilohertz range, and with average optical powers within the several tens of kilowatt category.

  11. Effect of Nicotine Patch on Energy Intake and Weight Gain in Postmenopausal Women during Smoking Cessation

    PubMed Central

    Allen, Alicia M.; Kleppinger, Alison; Lando, Harry; Oncken, Cheryl

    2013-01-01

    Introduction Post-cessation weight gain is a commonly cited barrier to smoking cessation. Some evidence suggests nicotine replacement therapy may limit post-cessation weight gain by reducing energy intake. This project aims to assess differential changes in energy intake and body weight during smoking cessation in a sample of postmenopausal women randomized to receive 21 mg nicotine or placebo patch for 12 weeks. Methods Postmenopausal women who smoked ≥10 cigarettes/day were enrolled in this double-blind randomized placebo-controlled study. Total energy intake (via four-day food diaries), body mass index (BMI; kg/m2), cigarettes per day and smoking status (self-report verified by exhaled carbon monoxide) were assessed at three time points: 2 weeks prior to quit date,12 weeks after quit date, and 12 months after smoking cessation treatment. Results Participants (n=119) were, on average, 55.8±6.7 years old with a baseline BMI of 27.0±5.2 and average cigarettes/day was 21.1±8.6. At Week 12, participants randomized to nicotine patch increased their mean caloric intake by 146.4±547.7 kcals/day whereas those on placebo patch decreased their caloric intake by 175.3±463.2 (f-value=10.1, p-value=0.002). Despite the differences in caloric intake, body weight remained similar between groups. Conclusions The results of this study indicate that nicotine patch may increase energy intake during treatment, and does not prevent post-cessation weight gain in postmenopausal smokers. Additional research is needed to replicate these findings and assess whether different forms of nicotine replacement therapy influence caloric intake and post-cessation weight gain in postmenopausal smokers. PMID:24183127

  12. Body composition and energy and protein nutritional requirements for weight gain in Santa Ines crossbred sheep.

    PubMed

    Cutrim, Darley Oliveira; Alves, Kaliandra Souza; dos Santos, Rozilda da Conceição; da Mata, Vanessa Jaqueline Veloso; Oliveira, Luis Rennan Sampaio; Gomes, Daiany Íris; Mezzomo, Rafael

    2016-03-01

    This study was conducted to evaluate the body composition and net energy and protein requirements for weight gain in Santa Ines crossbred sheep. Thirty woolless, 4-month-old, castrated male sheep with an initial body weight (BW) of 19.77 ± 1.99 kg were used. Six animals (reference group) were slaughtered after the adaptation period to estimate empty body weight (EBW) and initial body composition. The remaining 24 animals were randomly distributed among four treatments (experimental diets) and slaughtered when they reached 30.24 ± 0.78 kg BW. The body composition ranged from 162.88 to 160.4 g protein/kg EBW, from 59.49 to 164.23 g fat/kg EBW and from 1.54 to 2.46 Mcal energy/kg EBW for animals ranging between 20 and 30 kg BW. The net energy requirement for Santa Ines crossbred sheep linearly increased when BW increased from 20 to 30 kg. Within that same weight range, the net protein requirement for weight gain in sheep was constant, ranging from 12.61 to 12.42 g/day to 100 g daily weight gain.

  13. Solar and internal gain adjustments in calculation of energy conservation savings

    NASA Astrophysics Data System (ADS)

    Christensen, C.; Wortman, D.

    1983-07-01

    Heating degree days are often used as a climatic measure in building energy calculations. To account for the effects of solar and internal gains, degree days at a lower base temperature are sometimes used, or the number of degree days is adjusted downward by a degree-day correction factor. A theoretical derivation which demonstrates that ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) C sub d factors are not the appropriate correction factors for calculation of energy savings from envelope conservation measures is presented. The results of this derivation can be used to develop new correlation factors appropriate for savings calculations.

  14. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    DOE PAGES

    Litos, M.; Adli, E.; Allen, J. M.; ...

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gainmore » results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.« less

  15. Numerical simulation of the explosion dynamics and energy release from high-gain ICF targets

    SciTech Connect

    MacFarlane, J.J.; Sawan, M.E.; Moses, G.A.; Wang, P.; Olson, R.E.

    1996-12-31

    Results from numerical simulations are presented describing the explosion energetics of a high-gain indirect-drive ICF target. The light ion fusion LIBRA-SP target, which consists of an x-ray driven capsule embedded in a spherical foam-filled hohlraum, is imploded using 12 prepulse and 12 full power Li beams containing a total energy of 8 MJ. Here, we report on the dynamics of the target energy release, focussing in particular on the partitioning of energy between x rays, neutrons, and target debris kinetic energy. Our results indicate that 72% and 22% of the 552 MJ yield is emitted by the target in the form of neutrons and x-rays, respectively. Calculated emergent spectra for the target neutrons and x rays are also presented. 12 refs., 5 figs., 1 tab.

  16. Self-Amplified Spontaneous Emission Free-Electron Laser with an Energy-Chirped Electron Beam and Undulator Tapering

    SciTech Connect

    Giannessi, L.; Ciocci, F.; Dattoli, G.; Del Franco, M.; Petralia, A.; Quattromini, M.; Ronsivalle, C.; Sabia, E.; Spassovsky, I.; Surrenti, V.; Bacci, A.; Rossi, A. R.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Cultrera, L.; Filippetto, D.; Di Pirro, G.; Ferrario, M.; Ficcadenti, L.

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  17. Self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering.

    PubMed

    Giannessi, L; Bacci, A; Bellaveglia, M; Briquez, F; Castellano, M; Chiadroni, E; Cianchi, A; Ciocci, F; Couprie, M E; Cultrera, L; Dattoli, G; Filippetto, D; Del Franco, M; Di Pirro, G; Ferrario, M; Ficcadenti, L; Frassetto, F; Gallo, A; Gatti, G; Labat, M; Marcus, G; Moreno, M; Mostacci, A; Pace, E; Petralia, A; Petrillo, V; Poletto, L; Quattromini, M; Rau, J V; Ronsivalle, C; Rosenzweig, J; Rossi, A R; Rossi Albertini, V; Sabia, E; Serluca, M; Spampinati, S; Spassovsky, I; Spataro, B; Surrenti, V; Vaccarezza, C; Vicario, C

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  18. Multi-stage FEL amplifier with diaphragm focusing line as direct energy driver for inertial confinement fusion

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    An FEL based energy driver for Inertial Confinement Fusion (ICF) is proposed. The key element of the scheme is free electron laser system. Novel technical solutions, namely, using of multichannel, multi-stage FEL amplifier with diaphragm focusing line, reveal a possibility to construct the FEL system operating at radiation wavelength {lambda} = 0.5 {mu}m and providing flush energy E = 1 MJ and brightness 4 x 10{sup 22} W cm{sup -2} sr{sup -1} within steering pulse duration {tau} {approximately} 0.1-2 ns. Total energy efficiency of the proposed ICF energy driver is about of 11% and repetition rate is 40 Hz. It is shown that the FEL based ICF energy driver may be constructed at the present level of accelerator technique R& D.

  19. When and how does a prominence-like jet gain kinetic energy?

    SciTech Connect

    Liu, Jiajia; Liu, Rui; Zhang, Quanhao; Liu, Kai; Shen, Chenglong; Wang, S.; Wang, Yuming

    2014-02-20

    A jet is a considerable amount of plasma being ejected from the chromosphere or lower corona into the higher corona and is a common phenomenon. Usually, a jet is triggered by a brightening or a flare, which provides the first driving force to push plasma upward. In this process, magnetic reconnection is thought to be the mechanism to convert magnetic energy into thermal, nonthermal, and kinetic energies. However, most jets could reach an unusual high altitude and end much later than the end of its associated flare. This fact implies that there is another way to continuously transfer magnetic energy into kinetic energy even after the reconnection. The picture described above is well known in the community, but how and how much magnetic energy is released through a way other than reconnection is still unclear. By studying a prominence-like jet observed by SDO/AIA and STEREO-A/EUVI, we find that the continuous relaxation of the post-reconnection magnetic field structure is an important process for a jet to climb up higher than it could through only reconnection. The kinetic energy of the jet gained through the relaxation is 1.6 times that gained from the reconnection. The resultant energy flux is hundreds of times larger than the flux required for the local coronal heating, suggesting that such jets are a possible source to keep the corona hot. Furthermore, rotational motions appear all the time during the jet. Our analysis suggests that torsional Alfvén waves induced during reconnection could not be the only mechanism to release magnetic energy and drive jets.

  20. Health and productivity gains from better indoor environments and their relationship with building energy efficiency

    SciTech Connect

    Fisk, William J.

    2000-04-01

    Theoretical considerations and empirical data suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases productivity and health. Existing literature contains moderate to strong evidence that characteristics of buildings and indoor environments significantly influence rates of communicable respiratory illness, allergy and asthma symptoms, sick building symptoms, and worker performance. While there is considerable uncertainty in the estimates of the magnitudes of productivity gains that may be obtained by providing better indoor environments, the projected gains are very large. For the U.S., the estimated potential annual savings and productivity gains are $6 to $14 billion from reduced respiratory disease, $2 to $4 billion from reduced allergies and asthma, $10 to $30 billion from reduced sick building syndrome symptoms, and $20 to $160 billion from direct improvements in worker performance that are unrelated to health. Productivity gains that are quantified and demonstrated could serve as a strong stimulus for energy efficiency measures that simultaneously improve the indoor environment.

  1. SirT1 gain-of-function increases energy efficiency and prevents diabetes in mice

    PubMed Central

    Banks, Alexander S.; Kon, Ning; Knight, Colette; Matsumoto, Michihiro; Gutiérrez-Juárez, Roger; Rossetti, Luciano; Gu, Wei; Accili, Domenico

    2011-01-01

    Summary In yeast, worms and flies, an extra copy of the gene encoding the Sirtuin Sir2 increases metabolic efficiency, as does administration of polyphenols like resveratrol, thought to act through Sirtuins. But evidence that Sirtuin gain-of-function results in increased metabolic efficiency in mammals is limited. We generated transgenic mice with moderate overexpression of SirT1, designed to mimic the Sirtuin gain-of-function that improves metabolism in C.elegans. These mice exhibit normal insulin sensitivity, but decreased food intake and locomotor activity, resulting in decreased energy expenditure. However, in various models of insulin resistance and diabetes, SirT1 transgenics display improved glucose tolerance due to decreased hepatic glucose production and increased adiponectin levels, without changes in body weight or composition. We conclude that SirT1 gain-of-function primes the organism for metabolic adaptation to insulin resistance, increasing hepatic insulin sensitivity and decreasing whole-body energy requirements. These findings have important implications for Sirtuin-based therapies in humans. PMID:18840364

  2. Multi-level multi-thermal-electron FDTD simulation of plasmonic interaction with semiconducting gain media: applications to plasmonic amplifiers and nano-lasers.

    PubMed

    Chen, X; Bhola, B; Huang, Y; Ho, S T

    2010-08-02

    Interactions between a semiconducting gain medium and confined plasmon-polaritons are studied using a multilevel multi-thermal-electron finite-difference time-domain (MLMTE-FDTD) simulator. We investigated the amplification of wave propagating in a plasmonic metal-semiconductor-metal (MSM) waveguide filled with semiconductor gain medium and obtained the conditions required to achieve net optical gain. The MSM gain waveguide is used to form a plasmonic semiconductor nano-ring laser(PSNRL) with an effective mode volume of 0.0071 microm3, which is about an order of magnitude smaller than the smallest demonstrated integrated photonic crystal based laser cavities. The simulation shows a lasing threshold current density of 1kA/cm2 for a 300 nm outer diameter ring cavity with 80 nm-wide ring. This current density can be realistically achieved in typical III-V semiconductor, which shows the experimental feasibility of the proposed PSNRL structure.

  3. Direct solar-pumped iodine laser amplifier

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Hwang, In H.; Stock, Larry V.

    1988-01-01

    A XeCl laser which was developed earlier for an iodine laser oscillator was modified in order to increase the output pulse energy of XeCl laser so that the iodine laser output energy could be increased. The electrical circuit of the XeCl laser was changed from a simple capacitor discharge circuit of the XeCl laser to a Marx system. Because of this improvement the output energy from the XeCl laser was increased from 60 mj to 80 mj. Subsequently, iodine laser output energy was increased from 100 mj to 3 mj. On the other hand, the energy storage capability and amplification characteristics of the Vortek solar simulator-pumped amplifier was calculated expecting the calculated amplification factor is about 2 and the energy extraction efficiency is 26 percent due to the very low input energy density to the amplifier. As a result of an improved kinetic modeling for the iodine solar simulator pumped power amplifier, it is found that the I-2 along the axis of the tube affects seriously the gain profile. For the gas i-C3F7I at the higher pressures, the gain will decrease due to the I-2 as the pumping intensity increases, and at these higher pressures an increase in flow velocity will increase the gain.

  4. Exploring the free energy gain of phase separation via Markov state modeling

    NASA Astrophysics Data System (ADS)

    Biedermann, Myra; Heuer, Andreas

    2017-07-01

    The gain of free energy upon unmixing is determined via application of Markov state modeling (MSM), using an Ising model with a fixed number of up- and down-spins. MSM yields reasonable estimates of the free energies. However, a closer look reveals significant differences that point to residual non-Markovian effects. These non-Markovian effects are rather unexpected since the typical criteria to study the quality of Markovianity indicate complete Markovian behavior. We identify the sparse connectivity between different Markov states as a likely reason for the observed bias. By studying a simple five state model system, we can analytically elucidate different sources of the bias and thus explain the different deviations that were observed for the Ising model. Based on this insight, we can modify the determination of the count matrix in the MSM approach. In this way, the estimation of the free energy is significantly improved.

  5. Exploring the free energy gain of phase separation via Markov state modeling.

    PubMed

    Biedermann, Myra; Heuer, Andreas

    2017-07-21

    The gain of free energy upon unmixing is determined via application of Markov state modeling (MSM), using an Ising model with a fixed number of up- and down-spins. MSM yields reasonable estimates of the free energies. However, a closer look reveals significant differences that point to residual non-Markovian effects. These non-Markovian effects are rather unexpected since the typical criteria to study the quality of Markovianity indicate complete Markovian behavior. We identify the sparse connectivity between different Markov states as a likely reason for the observed bias. By studying a simple five state model system, we can analytically elucidate different sources of the bias and thus explain the different deviations that were observed for the Ising model. Based on this insight, we can modify the determination of the count matrix in the MSM approach. In this way, the estimation of the free energy is significantly improved.

  6. Wireless Josephson amplifier

    SciTech Connect

    Narla, A.; Sliwa, K. M.; Hatridge, M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2014-06-09

    Josephson junction parametric amplifiers are playing a crucial role in the readout chain in superconducting quantum information experiments. However, their integration with current 3D cavity implementations poses the problem of transitioning between waveguide, coax cables, and planar circuits. Moreover, Josephson amplifiers require auxiliary microwave components, like directional couplers and/or hybrids, that are sources of spurious losses and impedance mismatches that limit measurement efficiency and amplifier tunability. We have developed a wireless architecture for these parametric amplifiers that eliminates superfluous microwave components and interconnects. This greatly simplifies their assembly and integration into experiments. We present an experimental realization of such a device operating in the 9–11 GHz band with about 100 MHz of amplitude gain-bandwidth product, on par with devices mounted in conventional sample holders. The simpler impedance environment presented to the amplifier also results in increased amplifier tunability.

  7. Wireless Josephson amplifier

    NASA Astrophysics Data System (ADS)

    Narla, A.; Sliwa, K. M.; Hatridge, M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2014-06-01

    Josephson junction parametric amplifiers are playing a crucial role in the readout chain in superconducting quantum information experiments. However, their integration with current 3D cavity implementations poses the problem of transitioning between waveguide, coax cables, and planar circuits. Moreover, Josephson amplifiers require auxiliary microwave components, like directional couplers and/or hybrids, that are sources of spurious losses and impedance mismatches that limit measurement efficiency and amplifier tunability. We have developed a wireless architecture for these parametric amplifiers that eliminates superfluous microwave components and interconnects. This greatly simplifies their assembly and integration into experiments. We present an experimental realization of such a device operating in the 9-11 GHz band with about 100 MHz of amplitude gain-bandwidth product, on par with devices mounted in conventional sample holders. The simpler impedance environment presented to the amplifier also results in increased amplifier tunability.

  8. Alterations in energy homeostasis to favour adipose tissue gain: A longitudinal study in healthy pregnant women.

    PubMed

    Abeysekera, Minoli V; Morris, Jack A; Davis, Gregory K; O'Sullivan, Anthony J

    2016-02-01

    Pregnancy is associated with an increase in body fat; however, excessive gestational weight gain predisposes to significant maternal and neonatal morbidity and mortality. It remains unclear whether alterations in energy homeostasis have a major influence on fat storage. To evaluate longitudinal changes in body composition and energy metabolism in healthy pregnant women. Body composition, energy expenditure and energy intake were measured longitudinally in 26 women with singleton pregnancies at 12-14 weeks, 24-26 weeks and 34-36 weeks of gestation. Fat mass (FM) and lean body mass (LBM) were measured using bio-impedance analysis, total energy expenditure (TEE) using the Sensewear Armband and energy intake through a 3-day food recall diary. Throughout pregnancy, all women remained healthy. Body weight increased by 10.8 ± 3.9 kg, from 67.3 ± 14.1 kg to 78.1 ± 13.8 kg from the first to the third trimester (P < 0.001). Body fat percentage increased by 4.5 ± 4.2% (P < 0.001). LBM also increased throughout pregnancy, by 3.9 ± 2.4 kg (P < 0.001). TEE increased significantly from the first to the third trimesters (9514 kJ/day to 10 263 kJ/day; P < 0.05). In contrast, energy expenditure due to physical activity, energy intake and macronutrient intake did not change significantly throughout pregnancy. Healthy women increase FM during pregnancy despite slight increases in TEE and no change in energy intake. This suggests that energy storage efficiency improves during pregnancy, which may be related to alterations in gut microbiota and activation of anabolic pathways during pregnancy. Clarifying factors leading to this more efficient fat and energy storing state, and the role of the pregnancy-related changes in gut microbiota, may be important for managing gestational weight gain. © 2015 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

  9. Improved-Bandwidth Transimpedance Amplifier

    NASA Technical Reports Server (NTRS)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  10. Generation of sub-50 fs pulses from a high-power Yb-doped fiber amplifier.

    PubMed

    Deng, Yujun; Chien, Ching-Yuan; Fidric, Bernard G; Kafka, James D

    2009-11-15

    We demonstrate the generation of 48 fs pulses with 18 W average power and 226 nJ of pulse energy from a Yb-doped fiber amplifier. The system uses a simple stretcher-free single-stage amplifier configuration operating in the parabolic pulse regime. The gain fiber length and pump wavelength are chosen in order to reduce the gain per unit length and generate both shorter pulses and higher pulse energy.

  11. On the design of pulsed dye laser amplifiers

    SciTech Connect

    Hnilo, A.A.; Martinez, O.E.

    1987-05-01

    The authors apply a formula for the small signal gain of a dye laser amplifier (obtained and verified in a previous work) to the case of a transverse pumped R6G amplifier. They trace a set of curves as a function of dimensionless parameters which give the gain for any combination of the parameters characterizing the amplifier (dye concentration, active length, etc.) The curves can be applied to design dye laser amplifiers for ultrashort pulses, both with saturated or unsaturated gain. They give numerical examples of the use of those curves that suggest that the new designs would require much lower pumping energies than the previous ones. Similar sets of curves can be easily obtained for other dyes or pumping configurations.

  12. Nanosecond vortex laser pulses with millijoule pulse energies from a Yb-doped double-clad fiber power amplifier

    NASA Astrophysics Data System (ADS)

    Koyama, Mio; Hirose, Tetsuya; Okida, Masahito; Miyamoto, Katsuhiko; Omatsu, Takashige

    2011-07-01

    Nanosecond vortex pulses were generated using a stressed, large-mode-area, Yb-doped, fiber amplifier with an off-axis coupling technique for the first time. A pulse energy of 0.83 mJ (corresponding to a peak power of 59 kW) was achieved at a pump power of 25.7 W. The optical-optical efficiency was measured to be 31%. The millijoule nanosecond vortex pulses will be potentially applied to novel material processing, such as metal microneedle fabrication.

  13. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  14. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  15. Deflection amplifier for image dissectors

    NASA Technical Reports Server (NTRS)

    Salomon, P. M.

    1977-01-01

    Balanced symmetrical y-axis amplifier uses zener-diode level shifting to interface operational amplifiers to high voltage bipolar output stages. Nominal voltage transfer characteristic is 40 differential output volts per input volt; bandwidth, between -3-dB points, is approximately 8 kHz; loop gain is nominally 89 dB with closed loop gain of 26 dB.

  16. Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment

    SciTech Connect

    Musumeci, P.; Boucher, S.; Doyuran, A.; England, R. J.; Pellegrini, C.; Rosenzweig, J. B.; Travish, G.; Yoder, R.; Tochitsky, S.Ya.; Joshi, C.; Ralph, J.; Sung, C.; Tolmachev, S.; Varfolomeev, A.; Varfolomeev, A. Jr.; Yarovoi, T.

    2004-12-07

    We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 {mu}m laser with power larger than 400 GW. The Rayleigh range of the laser, {approx} 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.

  17. Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment

    NASA Astrophysics Data System (ADS)

    Musumeci, P.; Tochitsky, S. Ya.; Boucher, S.; Doyuran, A.; England, R. J.; Joshi, C.; Pellegrini, C.; Ralph, J.; Rosenzweig, J. B.; Sung, C.; Tolmachev, S.; Travish, G.; Varfolomeev, A.; Varfolomeev, A.; Yarovoi, T.; Yoder, R.

    2004-12-01

    We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 μm laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.

  18. Innate olfactory preferences for flowers matching proboscis length ensure optimal energy gain in a hawkmoth

    PubMed Central

    Haverkamp, Alexander; Bing, Julia; Badeke, Elisa; Hansson, Bill S.; Knaden, Markus

    2016-01-01

    Cost efficient foraging is of especial importance for animals like hawkmoths or hummingbirds that are feeding ‘on the wing', making their foraging energetically demanding. The economic decisions made by these animals have a strong influence on the plants they pollinate and floral volatiles are often guiding these decisions. Here we show that the hawkmoth Manduca sexta exhibits an innate preference for volatiles of those Nicotiana flowers, which match the length of the moth's proboscis. This preference becomes apparent already at the initial inflight encounter, with the odour plume. Free-flight respiration analyses combined with nectar calorimetry revealed a significant caloric gain per invested flight energy only for preferred—matching—flowers. Our data therefore support Darwin's initial hypothesis on the coevolution of flower length and moth proboscis. We demonstrate that this interaction is mediated by an adaptive and hardwired olfactory preference of the moth for flowers offering the highest net-energy reward. PMID:27173441

  19. Electronic amplifiers: A compilation

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Several types of amplifiers and amplifier systems are considered. These include preamplifiers, high power amplifiers, buffer and isolation amplifiers, amplifier circuits, and general purpose amplifiers.

  20. Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating

    PubMed Central

    Bray, George A.; Smith, Steven R.; de Jonge, Lilian; Xie, Hui; Rood, Jennifer; Martin, Corby K.; Most, Marlene; Brock, Courtney; Mancuso, Susan; Redman, Leanne M.

    2013-01-01

    Context The role of diet composition in response to overeating and energy dissipation in humans is unclear. Objective To evaluate the effects of overconsumption of low, normal, and high protein diets on weight gain, energy expenditure, and body composition. Design, Setting, and Participants A single-blind, randomized controlled trial of 25 US healthy, weight-stable male and female volunteers, aged 18 to 35 years with a body mass index between 19 and 30. The first participant was admitted to the inpatient metabolic unit in June 2005 and the last in October 2007. Intervention After consuming a weight-stabilizing diet for 13 to 25 days, participants were randomized to diets containing 5% of energy from protein (low protein), 15% (normal protein), or 25% (high protein), which they were overfed during the last 8 weeks of their 10- to 12-week stay in the inpatient metabolic unit. Compared with energy intake during the weight stabilization period, the protein diets provided approximately 40% more energy intake, which corresponds to 954 kcal/d (95% CI, 884–1022 kcal/d). Main Outcome Measures Body composition was measured by dual-energy x-ray absorptiometry biweekly, resting energy expenditure was measured weekly by ventilated hood, and total energy expenditure by doubly labeled water prior to the overeating and weight stabilization periods and at weeks 7 to 8. Results Overeating produced significantly less weight gain in the low protein diet group (3.16 kg; 95% CI, 1.88–4.44 kg) compared with the normal protein diet group (6.05 kg; 95% CI, 4.84–7.26 kg) or the high protein diet group (6.51 kg; 95% CI, 5.23–7.79 kg) (P=.002). Body fat increased similarly in all 3 protein diet groups and represented 50% to more than 90% of the excess stored calories. Resting energy expenditure, total energy expenditure, and body protein did not increase during overfeeding with the low protein diet. In contrast, resting energy expenditure (normal protein diet: 160 kcal/d [95% CI, 102

  1. Extreme ultraviolet amplifier experiments at the LLNL Nova two-beam facility (abstract)

    NASA Astrophysics Data System (ADS)

    Shimkaveg, G.

    1990-10-01

    We present the results of our most recent experiments on extreme ultraviolet (XUV) and soft x-ray amplifiers conducted at LLNL's Nova laser two-beam facility. Of particular interest are high-Z nickel-like amplifiers which have demonstrated gain at photon energies above the carbon K edge, sub-Doppler-resolution spectra of amplified lines from long selenium amplifiers, absolutely timed streaked XUV and x-ray spectra from germanium amplifiers at a variety of L-shell ionization states, and gain measurements from neon-like silver amplifiers. The array of spectroscopic instruments utilized in these experiments will be described in detail. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  2. High-gain polymer optical waveguide amplifiers based on core-shell NaYF4/NaLuF4: Yb(3+), Er(3+) NPs-PMMA covalent-linking nanocomposites.

    PubMed

    Zhang, Meiling; Zhang, Weiwei; Wang, Fei; Zhao, Dan; Qu, Chunyang; Wang, Xibin; Yi, Yunji; Cassan, Eric; Zhang, Daming

    2016-11-09

    Waveguide amplifiers have always been significant key components for optical communication. Unfortunately, the low concentration of rare earth ions doped in the host material and the inadequate optimization of the waveguide structure have been the common bottleneck limitations. Here, a novel material, NaYF4/NaLuF4: 20% Yb(3+), 2% Er(3+) nanoparticle-Polymeric Methyl Methacrylate covalent-linking nanocomposite, was synthesized. The concentrations of Er(3+) and Yb(3+) doping increased an order of magnitude. Under a 980 nm laser excitation, highly efficient emission at 1.53 μm was obtained. The characteristic parameters of the single mode waveguide were carefully designed and optimized by using a finite difference method. A formulized iteration method is presented for solving the rate equations and the propagation equations of the EYCDWA, and both the steady state behavior and the gain were numerically simulated. The optimal Er(3+) and Yb(3+) concentrations are 2.8 × 10(26) m(-3) and 2.8 × 10(27) m(-3), and the optimal waveguide length is 1.3 cm. Both theoretical and experimental results indicated that, for an input signal power of 0.1 mW and a pump power of 400 mW, a net gain of 15.1 dB at 1530 nm is demonstrated. This result is the highest gain ever reported in polymer-based waveguide amplifiers doped with inorganic Er(3+)-Yb(3+) codoped nanocrystals.

  3. High-gain polymer optical waveguide amplifiers based on core-shell NaYF4/NaLuF4: Yb3+, Er3+ NPs-PMMA covalent-linking nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhang, Meiling; Zhang, Weiwei; Wang, Fei; Zhao, Dan; Qu, Chunyang; Wang, Xibin; Yi, Yunji; Cassan, Eric; Zhang, Daming

    2016-11-01

    Waveguide amplifiers have always been significant key components for optical communication. Unfortunately, the low concentration of rare earth ions doped in the host material and the inadequate optimization of the waveguide structure have been the common bottleneck limitations. Here, a novel material, NaYF4/NaLuF4: 20% Yb3+, 2% Er3+ nanoparticle-Polymeric Methyl Methacrylate covalent-linking nanocomposite, was synthesized. The concentrations of Er3+ and Yb3+ doping increased an order of magnitude. Under a 980 nm laser excitation, highly efficient emission at 1.53 μm was obtained. The characteristic parameters of the single mode waveguide were carefully designed and optimized by using a finite difference method. A formulized iteration method is presented for solving the rate equations and the propagation equations of the EYCDWA, and both the steady state behavior and the gain were numerically simulated. The optimal Er3+ and Yb3+ concentrations are 2.8 × 1026 m‑3 and 2.8 × 1027 m‑3, and the optimal waveguide length is 1.3 cm. Both theoretical and experimental results indicated that, for an input signal power of 0.1 mW and a pump power of 400 mW, a net gain of 15.1 dB at 1530 nm is demonstrated. This result is the highest gain ever reported in polymer-based waveguide amplifiers doped with inorganic Er3+-Yb3+ codoped nanocrystals.

  4. High-gain polymer optical waveguide amplifiers based on core-shell NaYF4/NaLuF4: Yb3+, Er3+ NPs-PMMA covalent-linking nanocomposites

    PubMed Central

    Zhang, Meiling; Zhang, Weiwei; Wang, Fei; Zhao, Dan; Qu, Chunyang; Wang, Xibin; Yi, Yunji; Cassan, Eric; Zhang, Daming

    2016-01-01

    Waveguide amplifiers have always been significant key components for optical communication. Unfortunately, the low concentration of rare earth ions doped in the host material and the inadequate optimization of the waveguide structure have been the common bottleneck limitations. Here, a novel material, NaYF4/NaLuF4: 20% Yb3+, 2% Er3+ nanoparticle-Polymeric Methyl Methacrylate covalent-linking nanocomposite, was synthesized. The concentrations of Er3+ and Yb3+ doping increased an order of magnitude. Under a 980 nm laser excitation, highly efficient emission at 1.53 μm was obtained. The characteristic parameters of the single mode waveguide were carefully designed and optimized by using a finite difference method. A formulized iteration method is presented for solving the rate equations and the propagation equations of the EYCDWA, and both the steady state behavior and the gain were numerically simulated. The optimal Er3+ and Yb3+ concentrations are 2.8 × 1026 m−3 and 2.8 × 1027 m−3, and the optimal waveguide length is 1.3 cm. Both theoretical and experimental results indicated that, for an input signal power of 0.1 mW and a pump power of 400 mW, a net gain of 15.1 dB at 1530 nm is demonstrated. This result is the highest gain ever reported in polymer-based waveguide amplifiers doped with inorganic Er3+-Yb3+ codoped nanocrystals. PMID:27827414

  5. Comparison of weight gain and energy intake after subthalamic versus pallidal stimulation in Parkinson's disease.

    PubMed

    Sauleau, Paul; Leray, Emmanuelle; Rouaud, Tiphaine; Drapier, Sophie; Drapier, Dominique; Blanchard, Sophie; Drillet, Gwenolla; Péron, Julie; Vérin, Marc

    2009-10-30

    To compare body mass index (BMI) and daily energy intake (DEI) after subthalamic versus pallidal deep brain stimulation (DBS). Weight gain following DBS in Parkinson's disease patients remains largely unexplained and no comparison of subthalamic and pallidal (GPi) stimulation has yet been performed. BMI and DEI, dopaminergic drug administration and motor scores were recorded in 46 patients with PD before STN (n = 32) or GPi (n = 14) DBS and 3 and 6 months after. At M6, BMI had increased by an average of 8.4% in the STN group and 3.2% in the GPi group. BMI increased in 28 STN and 9 GPi patients. This increase was significantly higher in the STN group (P < 0.048) and the difference remained significant after adjustment for reduced dopaminergic medication; 28.6% of GPi patients were overweight at 6 months (14.3% preoperatively) versus 37.5% of STN patients (21.9% preoperatively). Changes in BMI were negatively correlated with changes in dyskinesia in the GPi-DBS group. Food intake did not change in the two groups, either quantitatively or qualitatively. Frequent weight gain, inadequately explained by motor improvement or reduced dopaminergic drug dosage, occurred in subthalamic DBS patients. The difference between groups suggests additional factors in the STN group, such as homeostatic control center involvement.

  6. Multiple pass laser amplifier system

    DOEpatents

    Brueckner, Keith A.; Jorna, Siebe; Moncur, N. Kent

    1977-01-01

    A laser amplification method for increasing the energy extraction efficiency from laser amplifiers while reducing the energy flux that passes through a flux limited system which includes apparatus for decomposing a linearly polarized light beam into multiple components, passing the components through an amplifier in delayed time sequence and recombining the amplified components into an in phase linearly polarized beam.

  7. Linseed Dietary Fibers Reduce Apparent Digestibility of Energy and Fat and Weight Gain in Growing Rats

    PubMed Central

    Kristensen, Mette; Bach Knudsen, Knud Erik; Jørgensen, Henry; Oomah, David; Bügel, Susanne; Toubro, Søren; Tetens, Inge; Astrup, Arne

    2013-01-01

    Dietary fibers (DF) may affect energy balance, an effect often ascribed to the viscous nature of some water soluble DF, which affect luminal viscosity and thus multiple physiological processes. We have tested the hypothesis that viscous linseed DF reduce apparent nutrient digestibility, and limit weight gain, in a randomized feeding trial where 60 male, growing, Wistar rats, with an initial weight of ~200 g, were fed different diets (n = 10 per group): low DF control (C), 5% DF from cellulose (5-CEL), CEL + 5% DF from whole (5-WL) or ground linseed (5-GL), CEL + 5% DF from linseed DF extract (5-LDF), and CEL + 10% DF from linseed DF extract (10-LDF). Diets were provided ad libitum for 21 days. Feed intake and faecal output were measured during days 17–21. Faecal fat excretion increased with increasing DF content and was highest in the 10-LDF group. Apparent fat digestibility was highest with the C diet (94.9% ± 0.8%) and lowest (74.3% ± 0.6%) with the 10-LDF diet, and decreased in a non-linear manner with increasing DF (p < 0.001). Apparent fat digestibility also decreased with increased accessibility of DF (5-WL vs. 5-GL) and when the proportion of viscous DF increased (5-GL vs. 5-LDF). The 10-LDF resulted in a lower final body weight (258 ± 6.2 g) compared to C (282 ± 5.9 g), 5-CEL (281 ± 5.9 g), and 5-WL (285 ± 5.9 g) (p < 0.05). The 10-LDF diet reduced body fat compared to 5-CEL (p < 0.01). In conclusion, DF extracted from linseed reduced apparent energy and fat digestibility and resulted in restriction of body weight gain in growing rats. PMID:23966109

  8. When and How Does A Prominence-like Jet Gain Kinetic Energy?

    NASA Astrophysics Data System (ADS)

    Liu, J.; Wang, Y.; Zhang, Q.; Liu, K.; Shen, C.

    2013-12-01

    Usually a jet is triggered by a brightening or flare, which provides the first driving force. In this process, magnetic reconnection is thought to be the mechanism to convert magnetic energy into jet's kinetic energy. However, most jets could reach an unusual height and end far after the end of its associated flare. This fact implies another way continuously transferring magnetic energy into kinetic energy after the reconnection. This picture is well known, but how and how much magnetic energy is released through the way other than the reconnection is still unclear. Here, through studying a prominence-like jet observed by AIA and EUVI, we reveal the continuously relaxation of post-reconnection magnetic field structure is an important process to support a jet. The kinetic energy of the jet gained through this way is 1.6 times of that from the reconnection. The resultant energy flux is hundreds of the required for local coronal heating, suggesting such jets are a possible source to keep corona hot. Rotational motion appearing all the time during the jet implies the torsional Alfven wave induced during reconnection is not the only mechanism to release magnetic energy and drive jets. Left column: Difference images taken by SDO/AIA at 304A passband. The FOV of the images is 430"x430". Right column: Difference images from STEREO-A/EUVI at the same passband. The FOV is 450"x450". Since STEREO-A was 120 degree apart away from SDO on 2012 July 8, the SDO limb event right happened ondisk in the view of STEREO-A. Black and red solid curve: integrated intensity over the cross-section of the jet at different height at 19:11 UT and 19:47 UT, respectively. The two horizontal dashed lines are their average values. Black and red dashed curve with asterisks: axial speed with errors of the eight sub-jets shown in Figure 3 at 19:11 UT and 19:47 UT , respectively. Blue dashed curve with diamonds: angular speed with errors of the jet at different height.

  9. A grid amplifier

    NASA Technical Reports Server (NTRS)

    Kim, Moonil; Weikle, Robert M., II; Hacker, Jonathan B.; Delisio, Michael P.; Rutledge, David B.; Rosenberg, James J.; Smith, R. P.

    1991-01-01

    A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from a relative power measurement. This grid is a hybrid circuit, but the structure is suitable for fabrication as a monolithic wafer-scale integrated circuit, particularly at millimeter wavelengths.

  10. Spatial Light Amplifier Modulators

    NASA Technical Reports Server (NTRS)

    Eng, Sverre T.; Olsson, N. Anders

    1992-01-01

    Spatial light amplifier modulators (SLAM's) are conceptual devices that effect two-dimensional spatial modulation in optical computing and communication systems. Unlike current spatial light modulators, these provide gain. Optical processors incorporating SLAM's designed to operate in reflection or transmission mode. Each element of planar SLAM array is optical amplifier - surface-emitting diode laser. Array addressed electrically with ac modulating signals superimposed on dc bias currents supplied to lasers. SLAM device provides both desired modulation and enough optical gain to enable splitting of output signal into many optical fibers without excessive loss of power.

  11. A grid amplifier

    NASA Technical Reports Server (NTRS)

    Kim, Moonil; Weikle, Robert M., II; Hacker, Jonathan B.; Delisio, Michael P.; Rutledge, David B.; Rosenberg, James J.; Smith, R. P.

    1991-01-01

    A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from a relative power measurement. This grid is a hybrid circuit, but the structure is suitable for fabrication as a monolithic wafer-scale integrated circuit, particularly at millimeter wavelengths.

  12. Limit circuit prevents overdriving of operational amplifier

    NASA Technical Reports Server (NTRS)

    Openshaw, F. L.

    1967-01-01

    Cutoff-type high gain amplifier coupled by a diode prevents overdriving of operational amplifier. An amplified feedback signal offsets the excess input signal that tends to cause the amplifier to exceed its preset limit. The output is, therfore, held to the set clamp level.

  13. Remote Acquisition Amplifier For 50-Ohm Cable

    NASA Technical Reports Server (NTRS)

    Amador, Jose J.

    1995-01-01

    Buffer-amplifier unit designed to drive 50-Ohm cables up to 100 ft. (30 m) long, compensating for attenuation in cables and enabling remote operation of oscilloscopes. Variable resistor provides for adjustment of gain of amplifier, such that overall gain from input terminals of amplifier to output end of cable set to unity.

  14. Rare Earth Doped Fiber Amplifiers for the First Telecommunication Window

    NASA Astrophysics Data System (ADS)

    Sridhar, Balakrishnan

    A complete experimental and theoretical study of rare earth doped fiber-optic amplifiers for the first tele-communication window has been made. The thulium doped fluoride fiber amplifier is shown to provide amplification in the 800nm-820nm signal region. A complete steady state theoretical model has been presented and the model has been experimentally verified. The model predicts the gain, noise figure and the amplified spontaneous emission in the 800nm, 1470nm, 1900nm and 2300nm bands. The effect of population trapping at the ^3F_4 energy level of thulium ion is also shown with the help of the model. It has been shown that about 5 -15%o of the population is trapped at the ^3F _4 energy level. We have also shown theoretically, the expected gain and noise performance of Thulium doped fluoride fiber amplifiers pumped in the 680nm absorption band. The maximum gain at 806nm is slightly lower than with comparable 780 nm pumping. The gain bandwidth is however found to increase with 680nm pumping. The higher ASE at shorter wavelengths (<806nm) reduces the gain at the peak wavelength (806nm). This is a result of the better inversion with three level pumping at 680nm as compared to two level resonant pumping at 780nm. We report an efficient single mode erbium doped flouride fiber amplifier in the 850nm signal band for the first time. The amplification is through an up-conversion process. The erbium doped flouride fiber amplifier was pumped with an estimated pump power of 35mW at 792nm. We have also considered a theoretical model for a single mode erbium doped fluoride fiber amplifier. Efficient amplification occurs because of the strong excited state absorption at the pump wavelength from the ^4I_{13/2} energy level.

  15. Low Noise Optically Pre-amplified Lightwave Receivers and Other Applications of Fiber Optic Parametric Amplifiers

    DTIC Science & Technology

    2010-07-27

    noise performance, optical gain bandwidth, and power efficiency. An interesting alternative to the mature Erbium-doped fiber amplifier ( EDFA ) is the...fibers (HNLF) and high power booster EDFAs . The FOPA can provide a very wide gain bandwidth [2], very high gain (70 dB was demonstrated in [3]), and...amplified spontaneous emission (ASE) noise in EDFAs is also generated. It is sometimes referred to as amplified quantum noise. Maximum gain (at the gain

  16. Ignition feedback regenerative free electron laser (FEL) amplifier

    DOEpatents

    Kim, Kwang-Je; Zholents, Alexander; Zolotorev, Max

    2001-01-01

    An ignition feedback regenerative amplifier consists of an injector, a linear accelerator with energy recovery, and a high-gain free electron laser amplifier. A fraction of the free electron laser output is coupled to the input to operate the free electron laser in the regenerative mode. A mode filter in this loop prevents run away instability. Another fraction of the output, after suitable frequency up conversion, is used to drive the photocathode. An external laser is provided to start up both the amplifier and the injector, thus igniting the system.

  17. The impact of stopping high-energy oral nutritional supplements on eating behaviour and weight gain.

    PubMed

    Wright, Charlotte M; Chillingworth, Anna

    2015-11-01

    Many children referred to a tertiary feeding clinic are already taking high-energy oral nutritional supplements (HEOS), but these often seem not clinically useful. We undertook a retrospective review of all children on HEOS at the time of referral to the clinic in order to describe their subsequent progress in terms of growth and feeding behaviour. A total of 48 children were on HEOS at referral and withdrawal of HEOS was attempted in 38 children, aged median 3.0 years (range 0.7-10 years) who were taking volumes equivalent to 2/3 of total daily energy requirements. The children tended to be very short and slim (median height SD score (SDS) -2.0 (range -5.7 to 1.9); body mass index -2.0 (-5.1 to 1.9)). Half had normal neurodevelopment (ND) but 4 (11%) had learning disability and 4 (11%) severe ND problems. By last follow-up after 0.86 (0-2.9) years, 30 (79%) had stopped all feeds. Those who stopped had a mean (SD) change in weight of 0.08 (0.6) SDS (range -0.88 to +1.59). Five children (17%) showed significant catch-up weight gain after stopping feeds, of whom three had been referred for weight faltering and possible tube feeding. Improvement in feeding behaviour was documented in 76% (29). The use of HEOS in children suppresses appetite for solid food due to energy compensation. In some cases, HEOS may perpetuate or even cause weight faltering. It should not be assumed that failure to respond to HEOS is an indication for tube feeding. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  18. Energy gains predict the distribution of plains bison across populations and ecosystems.

    PubMed

    Babin, Jean-Sébastien; Fortin, Daniel; Wilmshurst, John F; Fortin, Marie-Eve

    2011-01-01

    Developing tools that help predict animal distribution in the face of environmental change is central to understanding ecosystem function, but it remains a significant ecological challenge. We tested whether a single foraging currency could explain bison (Bison bison) distribution in dissimilar environments: a largely forested environment in Prince Albert National Park (Saskatchewan, Canada) and a prairie environment in Grasslands National Park (Saskatchewan, Canada). We blended extensive behavioral observations, relocations of radio-collared bison, vegetation surveys, and laboratory analyses to spatially link bison distribution in the two parks and expected gains for different nutritional currencies. In Prince Albert National Park, bison were more closely associated with the distribution of plants that maximized their instantaneous energy intake rate (IDE) than their daily intake of digestible energy. This result reflected both bison's intensity of use of individual meadows and their selection of foraging sites within meadows. On this basis, we tested whether IDE could explain the spatial dynamics of bison reintroduced to Grasslands National Park. As predicted, bison distribution in this park best matched spatial patterns of plants offering rapid IDE rather than rapid sodium intake, phosphorus intake, or daily intake of digestible energy. Because the two study areas have very different plant communities, a phenomenological model of resource selection developed in one area could not be used to predict animal distribution in the other. We were able, however, to successfully infer the distribution of bison from their foraging objective. This consistency in foraging currency across ecosystems and populations provides a strong basis for forecasting animal distributions in novel and dynamic environments.

  19. High energy, single-polarized, single-transverse-mode, nanosecond pulses generated by a multi-stage Yb-doped photonic crystal fiber amplifier

    NASA Astrophysics Data System (ADS)

    Shen, Xinglai; Zhang, Haitao; Hao, He; Li, Dan; Li, Qinghua; Yan, Ping; Gong, Mali

    2015-06-01

    We report the construction of a cascaded fiber amplifier where a 40-μm-core-diameter photonic crystal fiber is utilized in the main amplifier stage. Single-transverse-mode, linearly-polarized, 7.5 ns pulses with 1.5 mJ energy, 123 kW peak power and 10 nm spectral bandwidth centered at 1062 nm are generated. To our knowledge, the pulse energy we obtain is the highest from 40-μm-core-diameter photonic crystal fibers, and also the highest for long pulses (>1 ns) with linear polarization and single transverse mode.

  20. New compressed Ti:sapphire femtosecond amplifier layout

    NASA Astrophysics Data System (ADS)

    Carson, Andrew J.; Barnes, Charles C.; Tenyakov, Sergey

    2006-02-01

    A novel new design for an 8-pass multipass Titanium doped sapphire femtosecond amplifier (MPA) is studied. Ultrafast amplifiers based on the chirped pulse amplification (CPA) technique have been widely used to amplify the output pulses of Kerr lens mode locked (KLM) Ti:sapphire lasers from the nanojoule to the microjoule level. The system presented here also takes advantage of CPA to reduce the peak power and thus the potential damage to optical components from self-focusing. The amplifier scheme is based on a single curved mirror and a Brewster cut Ti:sapphire laser rod. Optical excitation of the Ti:sapphire gain medium is achieved by pumping with a Q-switched and frequency doubled Nd:YLF laser at 527 nm. The rear face of the gain crystal is coated to form a high reflector for both the pumping wavelength (490-550 nm) and the amplified seed pulse (740-860 nm). In this configuration the gain crystal itself acts as a second mirror, reducing the size of the amplifier and allowing for the most effective use of the pumping energy. By employing a Brewster cut lasing crystal the amount of active gain material can be adjusted for maximum gain. The advantages of this approach, compared to traditional two curved mirror MPA designs, are the reduced foot print and the ability to easily adjust the amount of gain material. At the same time the system retains the low amplified spontaneous emission (ASE) and temporally clean output pulse characteristic of MPA systems.

  1. Optically dense Fe:ZnSe crystals for energy scaled gain switched lasing

    NASA Astrophysics Data System (ADS)

    Myoung, NoSoung; Fedorov, Vladimir V.; Mirov, Sergey B.

    2010-02-01

    This work is focused on study and optimization of diffusion of Fe in ZnSe from the metal phase, comparative spectroscopic characterization of kinetic properties of Fe:ZnSe crystals with a wide range of concentrations, and energy scaling of the Fe:ZnSe gain-switched laser. Iron doping of ZnSe polycrystals was performed by thermal diffusion from the iron film made by thermal evaporation process. Special cleaning of the ZnSe surfaces and optimization of the ZnSe substrate temperature and the rate of Fe evaporation resulted in significant enhancement of the diffusion process and enabled fabrication of high optical density crystals with Fe concentration up to 2x1020 cm-3. The diffusion coefficient and diffusion length of iron in ZnSe at 1000°C were estimated as 2.1x10-9 cm2/s and 1.3 mm, respectively. We report a detailed absorption, emission, and kinetics of fluorescence of Fe:ZnSe spectroscopy performed over a broad range of Fe concentrations (5x1018 - 2x1020 cm-3) and temperatures (14-300K) under direct 2.78μm excitation.

  2. Universal signal conditioning amplifier

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Hallberg, Carl; Cecil, Jim

    1994-01-01

    A state-of-the-art instrumentation amplifier capable of being used with most types of transducers has been developed at the Kennedy Space Center. This Universal Signal Conditioning Amplifier (USCA) can eliminate costly measurement setup item and troubleshooting, improve system reliability and provide more accurate data than conventional amplifiers. The USCA can configure itself for maximum resolution and accuracy based on information read from a RAM chip attached to each transducer. Excitation voltages or current are also automatically configured. The amplifier uses both analog and digital state-of-the-art technology with analog-to-digital conversion performed in the early stages in order to minimize errors introduced by offset and gain drifts in the analog components. A dynamic temperature compensation scheme has been designed to achieve and maintain 12-bit accuracy of the amplifier from 0 to 70 C. The digital signal processing section allows the implementation of digital filters up to 511th order. The amplifier can also perform real-time linearizations up to fourth order while processing data at a rate of 23.438 kS/s. Both digital and analog outputs are available from the amplifier.

  3. Dietary protein content alters energy expenditure and composition of the mass gain in grizzly bears (Ursus arctos horribilis).

    PubMed

    Felicetti, Laura A; Robbins, Charles T; Shipley, Lisa A

    2003-01-01

    Many fruits contain high levels of available energy but very low levels of protein and other nutrients. The discrepancy between available energy and protein creates a physiological paradox for many animals consuming high-fruit diets, as they will be protein deficient if they eat to meet their minimum energy requirement. We fed young grizzly bears both high-energy pelleted and fruit diets containing from 1.6% to 15.4% protein to examine the role of diet-induced thermogenesis and fat synthesis in dealing with high-energy-low-protein diets. Digestible energy intake at mass maintenance increased 2.1 times, and composition of the gain changed from primarily lean mass to entirely fat when the protein content of the diet decreased from 15.4% to 1.6%. Daily fat gain was up to three times higher in bears fed low-protein diets ad lib., compared with bears consuming the higher-protein diet and gaining mass at the same rate. Thus, bears eating fruit can either consume other foods to increase dietary protein content and reduce energy expenditure, intake, and potentially foraging time or overeat high-fruit diets and use diet-induced thermogenesis and fat synthesis to deal with their skewed energy-to-protein ratio. These are not discrete options but a continuum that creates numerous solutions for balancing energy expenditure, intake, foraging time, fat accumulation, and ultimately fitness, depending on food availability, foraging efficiency, bear size, and body condition.

  4. BOOK REVIEW: Inertial confinement fusion: The quest for ignition and energy gain using indirect drive

    NASA Astrophysics Data System (ADS)

    Yamanaka, C.

    1999-06-01

    Inertial confinement fusion (ICF) is an alternative way to control fusion which is based on scaling down a thermonuclear explosion to a small size, applicable for power production, a kind of thermonuclear internal combustion engine. This book extends many interesting topics concerning the research and development on ICF of the last 25 years. It provides a systematic development of the physics basis and also various experimental data on radiation driven implosion. This is a landmark treatise presented at the right time. It is based on the article ``Development of the indirect-drive approach to inertial confinement fusion and the target physics basis for ignition and gain'' by J.D. Lindl, published in Physics of Plasmas, Vol. 2, November 1995, pp. 3933-4024. As is well known, in the United States of America research on the target physics basis for indirect drive remained largely classified until 1994. The indirect drive approaches were closely related to nuclear weapons research at Lawrence Livermore and Los Alamos National Laboratories. In Japan and other countries, inertial confinement fusion research for civil energy has been successfully performed to achieve DT fuel pellet compression up to 1000 times normal density, and indirect drive concepts, such as the `Cannon Ball' scheme, also prevailed at several international conferences. In these circumstances the international fusion community proposed the Madrid Manifesto in 1988, which urged openness of ICF information to promote international collaboration on civil energy research for the future resources of the human race. This proposal was also supported by some of the US scientists. The United States Department of Energy revised its classification guidelines for ICF six years after the Madrid Manifesto. This first book from the USA treating target physics issues, covering topics from implosion dynamics to hydrodynamic stability, ignition physics, high-gain target design and the scope for energy applications is

  5. High-energy femtosecond Yb-doped all-fiber monolithic chirped-pulse amplifier at repetition rate of 1 MHz

    NASA Astrophysics Data System (ADS)

    Lv, Zhi-Guo; Teng, Hao; Wang, Li-Na; Wang, Jun-Li; Wei, Zhi-Yi

    2016-09-01

    A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification (CPA) technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied. We find that the compressed pulse duration is dependent on the amplified energy, the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ, while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ. The measured energy fluctuation is approximately 0.46% root mean square (RMS) over 2 h. The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines, medical therapy, and scientific studies. Project supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAC23B03), the National Key Basic Research Program of China (Grant No. 2013CB922401), and the National Natural Science Foundation of China (Grant No. 11474002).

  6. Spectroscopic properties and energy transfer of Tm(3+)/Ho(3+)-codoped TeO(2)-WO(3)-ZnO glasses for 1.47mum amplifier.

    PubMed

    Chen, Ganxin; Zhang, Qinyuan; Cheng, Yun; Zhao, Chun; Qian, Qi; Yang, Zhongmin; Jiang, Zhonghong

    2009-05-01

    We report on spectroscopic properties and energy transfer of Tm(3+)/Ho(3+)-codoped tungsten tellurite glasses for 1.47microm amplifier. Fluorescence spectra and the analysis of energy transfer indicate that Ho(3+) is an excellent codopant for 1.47microm emission. Comparing with other tellurite glasses, the radiative lifetime of the (3)H(4) level of Tm(3+) in tungsten tellurite glass is slightly lower, but the spontaneous emission probability, stimulated emission cross-section and the figure of merit for bandwidth are obviously larger. Although the pump efficiency of tungsten tellurite amplifier is approximately 50% less than that of fluoride glass, the figure of merit for bandwidth is approximately three times larger in tungsten tellurite glass than in fluoride glass. The results indicate that Tm(3+)/Ho(3+)-codoped tungsten tellurite glass is attractive for broadband amplifier.

  7. Reflections from a systematic review of dietary energy density and weight gain: is the inclusion of drinks valid?

    PubMed

    Johnson, L; Wilks, D C; Lindroos, A K; Jebb, S A

    2009-11-01

    The association between dietary energy density, increased energy intake and weight gain is supported by experimental evidence, but confirmation of an effect in free-living humans is limited. Experimental evidence supports a role of energy density in obesity through changes in food composition, not drinks consumption. The inclusion of drinks in the calculation creates a variable of questionable validity and has a substantive impact on the estimated energy density of the diet. We posit, based on the experimental evidence, that calculating the energy density of diets by excluding drinks and including calories from drinks as a covariate in the analysis is the most valid and reliable method of testing the relationship between energy density and weight gain in free-living humans. We demonstrate, by systematically reviewing existing observational studies of dietary energy density and weight gain in free-living humans, how current variation in the method for calculating energy density hampers the interpretation of these data. Reaching an a priori decision on the appropriate methodology will reduce the error caused by multiple comparisons and facilitate meaningful interpretation of epidemiological evidence to inform the development of effective obesity prevention strategies.

  8. Operational Amplifiers.

    ERIC Educational Resources Information Center

    Foxcroft, G. E.

    1986-01-01

    Addresses the introduction of low cost equipment into high school and college physical science classes. Examines the properties of an "ideal" operational amplifier and discusses how it might be used under saturated and non-saturated conditions. Notes the action of a "real" operational amplifier. (TW)

  9. Operational Amplifiers.

    ERIC Educational Resources Information Center

    Foxcroft, G. E.

    1986-01-01

    Addresses the introduction of low cost equipment into high school and college physical science classes. Examines the properties of an "ideal" operational amplifier and discusses how it might be used under saturated and non-saturated conditions. Notes the action of a "real" operational amplifier. (TW)

  10. Amplifier Distortion

    NASA Astrophysics Data System (ADS)

    Keeports, David

    2006-12-01

    By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

  11. Interactions of melatonin with mammalian mitochondria. Reducer of energy capacity and amplifier of permeability transition.

    PubMed

    Martinis, P; Zago, L; Maritati, M; Battaglia, V; Grancara, S; Rizzoli, V; Agostinelli, E; Bragadin, M; Toninello, A

    2012-05-01

    Melatonin, a metabolic product of the amino acid tryptophan, induces a dose-dependent energy drop correlated with a decrease in the oxidative phosphorylation process in isolated rat liver mitochondria. This effect involves a gradual decrease in the respiratory control index and significant alterations in the state 4/state 3 transition of membrane potential (ΔΨ). Melatonin, alone, does not affect the insulating properties of the inner membrane but, in the presence of supraphysiological Ca2+, induces a ΔΨ drop and colloid-osmotic mitochondrial swelling. These events are sensitive to cyclosporin A and the inhibitors of Ca2+ transport, indicative of the induction or amplification of the mitochondrial permeability transition. This phenomenon is triggered by oxidative stress induced by melatonin and Ca2+, with the generation of hydrogen peroxide and the consequent oxidation of sulfydryl groups, glutathione and pyridine nucleotides. In addition, melatonin, again in the presence of Ca2+, can also induce substantial release of cytochrome C and AIF (apoptosis-inducing factor), thus revealing its potential as a pro-apoptotic agent.

  12. Net electron energy gain induced by superluminal phase velocity and subluminal group velocity of a laser in a plasma channel

    NASA Astrophysics Data System (ADS)

    Cheng, Li-Hong; Yao, Zheng-Wei; Zhang, Xiao-Bo; Xue, Ju-Kui

    2017-08-01

    We examine electron dynamics induced by laser-plasma interaction in a two-dimensional plasma channel, taking into action the laser phase velocity as well as the group velocity. The coupled effects of phase velocity, group velocity, and plasma channel on electron dynamics are discussed in detail. The superluminal phase velocity and the corresponding subluminal group velocity of the laser result in rich and complex electron dynamics, which are depicted in the plane of the phase velocity and plasma charge density. For weak superluminosity of the phase velocity, the effects of the phase velocity and the group velocity can be neglected. For moderate superluminosity of the phase velocity, a cross-over region can exist, where the highly energetic electron could be found and the net energy gain is several times greater than the energy gain in vacuum. For strong superluminosity of the phase velocity, the dephasing rate increases and thus limits the electron energy gain from the laser. However, the asymmetric laser pulse, attributed by the superluminal phase velocity and the subluminal group velocity, results in the electron getting adjustable net energy gain from the laser. The electron oscillations are no longer limited by the charge density threshold and the electron can always get net energy from the laser. These electron dynamics can also be modified by adjusting the polarization of the laser.

  13. Energy calibration and gain correction of pixelated spectroscopic x-ray detectors using correlation optimised warping

    NASA Astrophysics Data System (ADS)

    Egan, C. K.; Scuffham, J. W.; Veale, M. C.; Wilson, M. D.; Seller, P.; Cernik, R. J.

    2017-01-01

    We describe the implementation of a reliable, robust and flexible gain correction and energy calibration algorithm for pixelated spectroscopic x-ray detectors. This algorithm uses a data processing method known as correlation optimised warping which aligns shifted datasets by means of a segmental linear stretching and compression of the spectral data in order to best correlate with a reference spectrum. We found the algorithm to be very robust against low-count spectroscopy, and was reliable in a range of different spectroscopic applications. Analysis of the integrated spectrum over all pixels for a Cerium K-alpha x-ray emission (at 34.72 keV) yielded a peak width of 2.45 keV before alignment and 1.11 keV after alignment. This compares favourably with the best in class pixel peak width of 0.76 keV and the mean peak width for all pixels of 1.00 keV. We also found the algorithm to be more user friendly than other peak-search algorithms because there is less external input. A key advantage of this algorithm is that it requires no prior knowledge of the input spectral characteristics, shape or quality of the data. This therefore lends itself to being useful for in-line processing and potentially removes the need for a separate calibration standard (e.g. a radioactive source). This algorithm can be used for any system that simultaneously collects large numbers of spectral data—including multi-element detectors.

  14. Robust gain-scheduling energy-to-peak control of vehicle lateral dynamics stabilisation

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zhang, Xinjie; Wang, Junmin

    2014-03-01

    In this paper, we investigate the vehicle lateral dynamics stabilisation problem to enhance vehicle handling by considering time-varying longitudinal velocity. The longitudinal velocity is described by a polytope with finite vertices and a novel technique is proposed to reduce the number of vertices. Since the tyre dynamics is nonlinear, the cornering stiffness is represented via the norm-bounded uncertainty. Concerning the time-varying velocity and the nonlinear tyre model, a linear parameter-varying vehicle model is obtained. As the velocity and the states are measurable, a gain-scheduling state-feedback controller is introduced. In the lateral control, the sideslip angle is required to be as small as possible and the yaw rate is constrained to a certain level. Thus, the control objective is to minimise the sideslip angle while the yaw rate is under a prescribed level or constrain both the sideslip angle and the yaw rate to prescribed levels. To consider the transient response of the closed-loop system, the ?-stability is also employed in the energy-to-peak control. The optimal controller can be obtained by solving a set of linear matrix inequalities. A nonlinear vehicle model is utilised to illustrate the design procedure and the effectiveness of the proposed design method. Finally, simulations and comparisons are carried out to show the significant advantage of the designed controller. Compared to the open-loop system, the closed-loop system with the designed controller can achieve much smaller sideslip angle and the yaw rate is closer to the desired yaw rate from a reference model. Therefore, the vehicle safety and the handling are both improved in our simulation cases.

  15. Providing for energy efficiency in homes and small buildings. Part II. Determining amount of energy lost or gained in a building

    SciTech Connect

    1980-06-01

    The training program is designed to educate students and individuals in the importance of conserving energy and to provide for developing skills needed in the application of energy-saving techniques that result in energy-efficient buildings. There are 3 parts to the training program. They are entitled: Understanding and Practicing Energy Conservation in Buildings; Determining Amount of Energy Lost or Gained in a Building; and Determining Which Practices Are Most Efficient and Installing Materials. For Part Two, it is recommended that cooling and heating load calculation manual (GRP 158) ASHRAE, 1979, be used. Specific subjects covered in Part II are: Terms Used to Measure Energy in Buildings; Understanding Heat Losses and Gains in Buildings; Estimating Heating Loads in Buildings; Special Applications for Estimating Cooling Loads in Buildings; Estimating Cooling Loads in Buildings; and Determining Cost Benefits of Using Energy-Saving Practices.

  16. Design and performance of an Automatic Gain Control system for the High Energy X-Ray Timing Experiment

    NASA Technical Reports Server (NTRS)

    Pelling, Michael R.; Rothschild, Richard E.; Macdonald, Daniel R.; Hertel, Robert; Nishiie, Edward

    1991-01-01

    The High Energy X-Ray Timing Experiment (HEXTE), currently under development for the X-Ray Timing Explorer (XTE) mission, employs a closed loop gain control system to attain 0.5 percent stabilization of each of eight-phoswich detector gains. This Automatic Gain Control (AGC) system utilizes a split window discriminator scheme to control the response of each detector pulse height analyzer to gated Am-241 X-ray events at 60 keV. A prototype AGC system has been implemented and tested within the gain perturbation environment expected to be experienced by the HEXTE instrument in flight. The AGC system and test configuration are described. Response, stability and noise characteristics are measured and compared with theoretical predictions. The system is found to be generally suitable for the HEXTE application.

  17. High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser

    NASA Astrophysics Data System (ADS)

    Musumeci, P.; Tochitsky, S. Ya.; Boucher, S.; Clayton, C. E.; Doyuran, A.; England, R. J.; Joshi, C.; Pellegrini, C.; Ralph, J. E.; Rosenzweig, J. B.; Sung, C.; Tolmachev, S.; Travish, G.; Varfolomeev, A. A.; Varfolomeev, A. A.; Yarovoi, T.; Yoder, R. B.

    2005-04-01

    Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an inverse-free-electron-laser (IFEL) accelerator experiment. A 14.5 MeV electron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and field amplitude. The Rayleigh range of the laser, ˜1.8 cm, is much shorter than the undulator length yielding a diffraction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator.

  18. High energy gain of trapped electrons in a tapered, diffraction-dominated inverse-free-electron laser.

    PubMed

    Musumeci, P; Tochitsky, S Ya; Boucher, S; Clayton, C E; Doyuran, A; England, R J; Joshi, C; Pellegrini, C; Ralph, J E; Rosenzweig, J B; Sung, C; Tolmachev, S; Travish, G; Varfolomeev, A A; Varfolomeev, A A; Yarovoi, T; Yoder, R B

    2005-04-22

    Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an inverse-free-electron-laser (IFEL) accelerator experiment. A 14.5 MeV electron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and field amplitude. The Rayleigh range of the laser, approximately 1.8 cm, is much shorter than the undulator length yielding a diffraction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator.

  19. Effects of metabolizable energy intake on tympanic temperature and average daily gain of steers finished in southern Chile during wintertime

    USDA-ARS?s Scientific Manuscript database

    A total of 24 Angus x Hereford steers (BW = 479.8 ± 4.48) were used to assess the effect of Metabolizable Energy Intake (MEI) on Average Daily Gain (ADG) and Tympanic Temperature (TT) during the wintertime in southern Chile. The study was conducted at the experimental field of the Catholic Universit...

  20. High stability amplifier

    NASA Technical Reports Server (NTRS)

    Adams, W. A.; Reinhardt, V. S. (Inventor)

    1983-01-01

    An electrical RF signal amplifier for providing high temperature stability and RF isolation and comprised of an integrated circuit voltage regulator, a single transistor, and an integrated circuit operational amplifier mounted on a circuit board such that passive circuit elements are located on side of the circuit board while the active circuit elements are located on the other side is described. The active circuit elements are embedded in a common heat sink so that a common temperature reference is provided for changes in ambient temperature. The single transistor and operational amplifier are connected together to form a feedback amplifier powered from the voltage regulator with transistor implementing primarily the desired signal gain while the operational amplifier implements signal isolation. Further RF isolation is provided by the voltage regulator which inhibits cross-talk from other like amplifiers powered from a common power supply. Input and output terminals consisting of coaxial connectors are located on the sides of a housing in which all the circuit components and heat sink are located.

  1. Universal signal conditioning amplifier

    NASA Technical Reports Server (NTRS)

    Larson, William E.; Hallberg, Carl; Medelius, Pedro J.

    1994-01-01

    Engineers at NASA's Kennedy Space Center have designed a signal conditioning amplifier which automatically matches itself to almost any kind of transducer. The product, called Universal Signal Conditioning Amplifier (USCA), uses state-of-the-art technologies to deliver high accuracy measurements. USCA's features which can be either programmable or automated include: voltage, current, or pulsed excitation, unlimited resolution gain, digital filtering and both analog and digital output. USCA will be used at Kennedy Space Center's launch pads for environmental measurements such as vibrations, strains, temperatures and overpressures. USCA is presently being commercialized through a co-funded agreement between NASA, the State of Florida, and Loral Test and Information Systems, Inc.

  2. Laser amplifier based on Raman amplification in plasma (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Vieux, Gregory; Cipiccia, Silvia; Lemos, Nuno R. C.; Ciocarlan, Cristian; Grant, Peter A.; Grant, David W.; Ersfeld, Bernhard; Hur, MinSup; Lepipas, Panagiotis; Manahan, Grace; Reboredo Gil, David; Subiel, Anna; Welsh, Gregor H.; Wiggins, S. Mark; Yoffe, Samuel R.; Farmer, John P.; Aniculaesei, Constantin; Brunetti, Enrico; Yang, Xue; Heathcote, Robert; Nersisyan, Gagik; Lewis, Ciaran L. S.; Pukhov, Alexander; Dias, João. Mendanha; Jaroszynski, Dino A.

    2017-05-01

    The increasing demand for high laser powers is placing huge demands on current laser technology. This is now reaching a limit, and to realise the existing new areas of research promised at high intensities, new cost-effective and technically feasible ways of scaling up the laser power will be required. Plasma-based laser amplifiers may represent the required breakthrough to reach powers of tens of petawatt to exawatt, because of the fundamental advantage that amplification and compression can be realised simultaneously in a plasma medium, which is also robust and resistant to damage, unlike conventional amplifying media. Raman amplification is a promising method, where a long pump pulse transfers energy to a lower frequency, short duration counter-propagating seed pulse through resonant excitation of a plasma wave that creates a transient plasma echelon that backscatters the pump into the probe. Here we present the results of an experimental campaign conducted at the Central Laser Facility. Pump pulses with energies up to 100 J have been used to amplify sub-nanojoule seed pulses to near-joule level. An unprecedented gain of eight orders of magnitude, with a gain coefficient of 180 cm-1 has been measured, which exceeds high-power solid-state amplifying media by orders of magnitude. High gain leads to strong competing amplification from noise, which reaches similar levels to the amplified seed. The observation of 640 Jsr-1 directly backscattered from noise, implies potential overall efficiencies greater than 10%.

  3. Acute partial sleep deprivation due to environmental noise increases weight gain by reducing energy expenditure in rodents.

    PubMed

    Parrish, Jennifer B; Teske, Jennifer A

    2017-01-01

    Chronic partial sleep deprivation (SD) by environmental noise exposure increases weight gain and feeding in rodents, which contrasts weight loss after acute SD by physical methods. This study tested whether acute environmental noise exposure reduced sleep and its effect on weight gain, food intake, physical activity, and energy expenditure (EE). It was hypothesized that acute exposure would (1) increase weight gain and feeding and (2) reduce sleep, physical activity, and EE (total and individual components); and (3) behavioral changes would persist throughout recovery from SD. Three-month old male Sprague-Dawley rats slept ad libitum, were noise exposed (12-h light cycle), and allowed to recover (36 h). Weight gain, food intake, sleep/wake, physical activity, and EE were measured. Acute environmental noise exposure had no effect on feeding, increased weight gain (P < 0.01), and reduced sleep (P < 0.02), physical activity (P < 0.03), total EE (P < 0.05), and several components (P < 0.05). Reductions in EE and physical activity persisted during recovery. Reductions in EE during sleep, rest, and physical activity reduce total EE and contribute to weight gain during acute SD and recovery from SD. These data emphasize the importance of increasing physical activity after SD to prevent obesity. © 2016 The Obesity Society.

  4. Evaluation of dairy cattle manure as a supplement to improve net energy gain in fermentative hydrogen production from sucrose.

    PubMed

    Perera, Karnayakage Rasika J; Nirmalakhandan, Nagamany

    2011-09-01

    This study evaluated fermentative biohydrogen production from sucrose supplemented with dairy cattle manure at different sucrose:manure ratios. Hydrogen yields found in this study (2.9-5.3M hydrogen/M sucrose) at ambient temperature are higher than literature results obtained at mesophilic temperatures. This study demonstrated that dairy cattle manure could serve as a buffering agent to maintain recommended pH levels; as a nutrient source to provide the required nutrients for hydrogen production; as a seed to produce hydrogen from sucrose; and as a co-substrate to improve the hydrogen yield. Based on an analysis of the net energy gain, it is concluded that positive net energy gains can be realized with non-thermal pretreatment and/or by combining dark fermentation with anaerobic digestion or microbial fuel cells to extract additional energy from the aqueous products of dark fermentation.

  5. Laser amplifier based on a neodymium glass rod 150 mm in diameter

    SciTech Connect

    Shaykin, A A; Fokin, A P; Soloviev, A A; Kuzmin, A A; Shaikin, I A; Burdonov, K F; Khazanov, E A; Charukhchev, A V

    2014-05-30

    A unique large-aperture neodymium glass rod amplifier is experimentally studied. The small-signal gain distribution is measured at different pump energies. The aperture-averaged gain is found to be 2.3. The stored energy (500 J), the maximum possible pump pulse repetition rate, and the depolarisation in a single pulse and in a series of pulses with a repetition rate of one pulse per five minutes are calculated based on the investigations performed. It is shown that the use of this amplifier at the exit of the existing laser can increase the output pulse energy from 300 to 600 J. (lasers)

  6. High-Frequency Power Gain in the Mammalian Cochlea

    NASA Astrophysics Data System (ADS)

    Maoiléidigh, Dáibhid Ó.; Hudspeth, A. J.

    2011-11-01

    Amplification in the mammalian inner ear is thought to result from a nonlinear active process known as the cochlear amplifier. Although there is much evidence that outer hair cells (OHCs) play a central role in the cochlear amplifier, the mechanism of amplification remains uncertain. In non-mammalian ears hair bundles can perform mechanical work and account for the active process in vitro, yet in the mammalian cochlea membrane-based electromotility is required for amplification in vivo. A key issue is how OHCs conduct mechanical power amplification at high frequencies. We present a physical model of a segment of the mammalian cochlea that can amplify the power of external signals. In this representation both electromotility and active hair-bundle motility are required for mechanical power gain at high frequencies. We demonstrate how the endocochlear potential, the OHC resting potential, Ca2+ gradients, and ATP-fueled myosin motors serve as the energy sources underlying mechanical power gain in the cochlear amplifier.

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

    PubMed

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

    2007-10-20

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

  8. Power neodymium-glass amplifier of a repetitively pulsed laser

    NASA Astrophysics Data System (ADS)

    Vinogradov, Aleksandr V.; Gaganov, V. E.; Garanin, Sergey G.; Zhidkov, N. V.; Krotov, V. A.; Martynenko, S. P.; Pozdnyakov, E. V.; Solomatin, I. I.

    2011-11-01

    A neodymium-glass diode-pumped amplifier with a zigzag laser beam propagation through the active medium was elaborated; the amplifier is intended for operation in a repetitively pulsed laser. An amplifier unit with an aperture of 20 × 25 mm and a ~40-cm long active medium was put to a test. The energy of pump radiation amounts to 140 J at a wavelength of 806 nm for a pump duration of 550 μs. The energy parameters of the amplifier were experimentally determined: the small-signal gain per pass ~3.2, the linear gain ~0.031 cm-1 with a nonuniformity of its distribution over the aperture within 15%, the stored energy of 0.16 — 0.21 J cm-3. The wavefront distortions in the zigzag laser-beam propagation through the active element of the amplifier did not exceed 0.4λ (λ = 0.63 μm is the probing radiation wavelength).

  9. Casimir forces in multilayer magnetodielectrics with both gain and loss

    SciTech Connect

    Amooghorban, Ehsan; Wubs, Martijn; Mortensen, N. Asger; Kheirandish, Fardin

    2011-07-15

    A path-integral approach to the quantization of the electromagnetic field in a linearly amplifying magnetodielectric medium is presented. Two continua of inverted harmonic oscillators are used to describe the polarizability and magnetizability of the amplifying medium. The causal susceptibilities of the amplifying medium, with negative imaginary parts in finite frequency intervals, are identified and their relationships to microscopic coupling functions are determined. By carefully relating the two-point functions of the field theory to the optical Green functions, we calculate the Casimir energy and Casimir forces for a multilayer magnetodielectric medium with both gain and loss. We point out the essential differences with a purely passive layered medium. For a single layer, we find different bounds on the Casimir force for fully amplifying and for lossy media. The force is attractive in both cases, even if the medium exhibits negative refraction. From our Lagrangian we also derive by canonical quantization the postulates of the phenomenological theory of amplifying magnetodielectrics.

  10. Risperidone-induced weight gain is mediated through shifts in the gut microbiome and suppression of energy expenditure.

    PubMed

    Bahra, Sarah M; Weidemann, Benjamin J; Castro, Ana N; Walsh, John W; deLeon, Orlando; Burnett, Colin M L; Pearson, Nicole A; Murry, Daryl J; Grobe, Justin L; Kirby, John R

    2015-11-01

    Risperidone is a second-generation antipsychotic that causes weight gain. We hypothesized that risperidone-induced shifts in the gut microbiome are mechanistically involved in its metabolic consequences. Wild-type female C57BL/6J mice treated with risperidone (80 μg/day) exhibited significant excess weight gain, due to reduced energy expenditure, which correlated with an altered gut microbiome. Fecal transplant from risperidone-treated mice caused a 16% reduction in total resting metabolic rate in naïve recipients, attributable to suppression of non-aerobic metabolism. Risperidone inhibited growth of cultured fecal bacteria grown anaerobically more than those grown aerobically. Finally, transplant of the fecal phage fraction from risperidone-treated mice was sufficient to cause excess weight gain in naïve recipients, again through reduced energy expenditure. Collectively, these data highlight a major role for the gut microbiome in weight gain following chronic use of risperidone, and specifically implicates the modulation of non-aerobic resting metabolism in this mechanism.

  11. Risperidone-induced weight gain is mediated through shifts in the gut microbiome and suppression of energy expenditure

    PubMed Central

    Bahr, Sarah M.; Weidemann, Benjamin J.; Castro, Ana N.; Walsh, John W.; deLeon, Orlando; Burnett, Colin M.L.; Pearson, Nicole A.; Murry, Daryl J.; Grobe, Justin L.; Kirby, John R.

    2015-01-01

    Risperidone is a second-generation antipsychotic that causes weight gain. We hypothesized that risperidone-induced shifts in the gut microbiome are mechanistically involved in its metabolic consequences. Wild-type female C57BL/6J mice treated with risperidone (80 μg/day) exhibited significant excess weight gain, due to reduced energy expenditure, which correlated with an altered gut microbiome. Fecal transplant from risperidone-treated mice caused a 16% reduction in total resting metabolic rate in naïve recipients, attributable to suppression of non-aerobic metabolism. Risperidone inhibited growth of cultured fecal bacteria grown anaerobically more than those grown aerobically. Finally, transplant of the fecal phage fraction from risperidone-treated mice was sufficient to cause excess weight gain in naïve recipients, again through reduced energy expenditure. Collectively, these data highlight a major role for the gut microbiome in weight gain following chronic use of risperidone, and specifically implicates the modulation of non-aerobic resting metabolism in this mechanism. PMID:26870798

  12. Low levels of physical activity are associated with dysregulation of energy intake and fat mass gain over 1 year12

    PubMed Central

    Shook, Robin P; Hand, Gregory A; Drenowatz, Clemens; Hebert, James R; Paluch, Amanda E; Blundell, John E; Hill, James O; Katzmarzyk, Peter T; Church, Timothy S; Blair, Steven N

    2015-01-01

    Background: Previous studies suggest that appetite may be dysregulated at low levels of activity, creating an energy imbalance that results in weight gain. Objective: The aim was to examine the relation between energy intake, physical activity, appetite, and weight gain during a 1-y follow-up period in a large sample of adults. Design: Participants included 421 individuals (mean ± SD age: 27.6 ± 3.8 y). Measurements included the following: energy intake with the use of interviewer-administered dietary recalls and calculated by using changes in body composition and energy expenditure, moderate-to-vigorous physical activity (MVPA) with the use of an arm-based monitor, body composition with the use of dual-energy X-ray absorptiometry, and questionnaire-derived perceptions of dietary restraint, disinhibition, hunger, and control of eating. Participants were grouped at baseline into quintiles of MVPA (min/d) by sex. Measurements were repeated every 3 mo for 1 y. Results: At baseline, an inverse relation existed between body weight and activity groups, with the least-active group (15.7 ± 9.9 min MVPA/d, 6062 ± 1778 steps/d) having the highest body weight (86.3 ± 13.2 kg) and the most-active group (174.5 ± 60.5 min MVPA/d, 10260 ± 3087 steps/d) having the lowest body weight (67.5 ± 11.0 kg). A positive relation was observed between calculated energy intake and activity group, except in the lowest quintile of activity. The lowest physical activity group reported higher levels of disinhibition (P = 0.07) and cravings for savory foods (P = 0.03) compared with the group with the highest level of physical activity. Over 1 y of follow-up, the lowest activity group gained the largest amount of fat mass (1.7 ± 0.3 kg) after adjustment for change in MVPA and baseline fat mass. The odds of gaining >3% of fat mass were between 1.8 and 3.8 times as high for individuals in the least-active group as for those in the middle activity group. Conclusions: These results suggest

  13. LOGARITHMIC AMPLIFIER

    DOEpatents

    Wade, E.J.; Stone, R.S.

    1959-03-10

    Electronic,amplifier circuits, especially a logai-ithmic amplifier characterizxed by its greatly improved strability are discussed. According to the in ention, means are provided to feed bach the output valtagee to a diode in the amplifier input circuit, the diode being utilized to produce the logarithmic characteristics. The diode is tics, The diode isition therewith and having its filament operated from thc same source s the filament of the logarithmic diode. A bias current of relatively large value compareii with the signal current is continuously passed through the compiting dioie to render the diode insensitivy to variations in the signal current. by this odes kdu to variaelled, so that the stability of the amlifier will be unimpaired.

  14. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density.

    PubMed

    Hazen, Elliott Lee; Friedlaender, Ari Seth; Goldbogen, Jeremy Arthur

    2015-10-01

    Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.

  15. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density

    PubMed Central

    Hazen, Elliott Lee; Friedlaender, Ari Seth; Goldbogen, Jeremy Arthur

    2015-01-01

    Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency. PMID:26601290

  16. Electrospun Amplified Fiber Optics

    PubMed Central

    2015-01-01

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm–1). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics. PMID:25710188

  17. High input impedance amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L.

    1995-01-01

    High input impedance amplifiers are provided which reduce the input impedance solely to a capacitive reactance, or, in a somewhat more complex design, provide an extremely high essentially infinite, capacitive reactance. In one embodiment, where the input impedance is reduced in essence, to solely a capacitive reactance, an operational amplifier in a follower configuration is driven at its non-inverting input and a resistor with a predetermined magnitude is connected between the inverting and non-inverting inputs. A second embodiment eliminates the capacitance from the input by adding a second stage to the first embodiment. The second stage is a second operational amplifier in a non-inverting gain-stage configuration where the output of the first follower stage drives the non-inverting input of the second stage and the output of the second stage is fed back to the non-inverting input of the first stage through a capacitor of a predetermined magnitude. These amplifiers, while generally useful, are very useful as sensor buffer amplifiers that may eliminate significant sources of error.

  18. Electrospun amplified fiber optics.

    PubMed

    Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

    2015-03-11

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.

  19. Energy gap in the aetiology of body weight gain and obesity: a challenging concept with a complex evaluation and pitfalls.

    PubMed

    Schutz, Yves; Byrne, Nuala M; Dulloo, Abdul; Hills, Andrew P

    2014-01-01

    The concept of energy gap(s) is useful for understanding the consequence of a small daily, weekly, or monthly positive energy balance and the inconspicuous shift in weight gain ultimately leading to overweight and obesity. Energy gap is a dynamic concept: an initial positive energy gap incurred via an increase in energy intake (or a decrease in physical activity) is not constant, may fade out with time if the initial conditions are maintained, and depends on the 'efficiency' with which the readjustment of the energy imbalance gap occurs with time. The metabolic response to an energy imbalance gap and the magnitude of the energy gap(s) can be estimated by at least two methods, i.e. i) assessment by longitudinal overfeeding studies, imposing (by design) an initial positive energy imbalance gap; ii) retrospective assessment based on epidemiological surveys, whereby the accumulated endogenous energy storage per unit of time is calculated from the change in body weight and body composition. In order to illustrate the difficulty of accurately assessing an energy gap we have used, as an illustrative example, a recent epidemiological study which tracked changes in total energy intake (estimated by gross food availability) and body weight over 3 decades in the US, combined with total energy expenditure prediction from body weight using doubly labelled water data. At the population level, the study attempted to assess the cause of the energy gap purported to be entirely due to increased food intake. Based on an estimate of change in energy intake judged to be more reliable (i.e. in the same study population) and together with calculations of simple energetic indices, our analysis suggests that conclusions about the fundamental causes of obesity development in a population (excess intake vs. low physical activity or both) is clouded by a high level of uncertainty. © 2014 S. Karger GmbH, Freiburg.

  20. Multistaged stokes injected Raman capillary waveguide amplifier

    DOEpatents

    Kurnit, Norman A.

    1980-01-01

    A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

  1. Energy Scaling of Nanosecond Gain-Switched Cr2+:ZnSe Lasers

    DTIC Science & Technology

    2011-01-01

    Keywords: infrared laser, solid - state lasers, chromium, gain-switched 1. INTRODUCTION Since the first demonstration of the laser 50 years ago [1...unlimited 13. SUPPLEMENTARY NOTES Proceedings Vol. 7912 Solid State Lasers XX: Technology and Devices, Date: 15 February 2011 14. ABSTRACT In this...Berry, P., A., and Schepler, K. L., ൔ-Watt CW Polycrystalline Cr2+:ZnSe Laser Pumped by Tm-fiber Laser," Proc. Advanced Solid State Photonics , WB30

  2. Calculation of the gain coefficient in cryogenically cooled Yb : YAG disks at high heat generation rates

    SciTech Connect

    Vadimova, O L; Mukhin, I B; Kuznetsov, I I; Palashov, O V; Perevezentsev, E A; Khazanov, Efim A

    2013-03-31

    We have calculated the stored energy and gain coefficient in disk gain elements cooled to cryogenic temperatures. The problem has been solved with allowance for intense heat generation, amplified spontaneous emission and parasitic lasing, without averaging over any spatial coordinate. The numerical simulation results agree well with experimental data, in particular at high heat generation rates. Experimental data and theoretical analysis indicate that composite disk gain elements containing an undoped region can store considerably more energy due to suppression of amplified spontaneous emission and parasitic lasing. (extreme light fields and their applications)

  3. Foraging decisions of bison for rapid energy gains can explain the relative risk to neighboring plants in complex swards.

    PubMed

    Courant, Sabrina; Fortin, Daniel

    2010-06-01

    Herbivores commonly base their foraging decisions not only on the intrinsic characteristics of plants, but also on the attributes of neighboring species. Although herbivores commonly orient their food choices toward the maximization of energy intake, the impact of such choices on neighboring plants remains largely unexplored. We evaluated whether foraging decisions by herbivores aiming at a rapid intake of digestible energy could explain multiple neighboring effects in complex swards. Specifically, we assessed how spatial patterns of occurrence of Carex atherodes, a highly profitable sedge species, could control the risk of bison (Bison bison) herbivory for seven other plant species. The foraging behavior of 70 free-ranging bison was evaluated in their natural environment during summer, and then related to plant characteristics. We used this information to estimate the instantaneous intake rate of digestible energy at individual feeding stations. We found that neighbor contrast defense and associational susceptibility can both be explained by simple foraging rules of energy maximization. Energy gains were higher when C. atherodes was consumed while avoiding the species for which we detected neighbor contrast defense. The lower intake rate associated with their consumption was due to an increase in handling time caused by their small size relative to C. atherodes. Bison also had higher energy gains by consuming instead of avoiding the plant species that experienced associational susceptibility. Because most of these plants were at least as tall as C. atherodes, their presence increased the heterogeneity of the grazed stratum. Avoiding their consumption increased handling time thereby reducing the instantaneous rate of energy intake. Overall, we found that bison adjust their fine-scale foraging decisions to vertical and horizontal sward structures in a way that maximizes their energy intake rate. Energy maximization principles thus provide a valuable framework to

  4. Semi-physical Identification and State Estimation of Energy Intake for Interventions to Manage Gestational Weight Gain

    PubMed Central

    Guo, Penghong; Rivera, Daniel E.; Downs, Danielle S.; Savage, Jennifer S.

    2016-01-01

    Excessive gestational weight gain (i.e., weight gain during pregnancy) is a significant public health concern, and has been the recent focus of novel, control systems-based interventions. This paper develops a control-oriented dynamical systems model based on a first-principles energy balance model from the literature, which is evaluated against participant data from a study targeted to obese and overweight pregnant women. The results indicate significant under-reporting of energy intake among the participant population. A series of approaches based on system identification and state estimation are developed in the paper to better understand and characterize the extent of under-reporting; these range from back-calculating energy intake from a closed-form of the energy balance model, to a constrained semi-physical identification approach that estimates the extent of systematic under-reporting in the presence of noise and possibly missing data. Additionally, we describe an adaptive algorithm based on Kalman filtering to estimate energy intake in real-time. The approaches are illustrated with data from both simulated and actual intervention participants. PMID:27570366

  5. Amplified Policymaking

    ERIC Educational Resources Information Center

    Prince, Katherine; Woempner, Carolyn

    2010-01-01

    This brief examines the policy implications of two drivers of change presented in the "2020 Forecast: Creating the Future of Learning"-- Pattern Recognition and Amplified Organization. These drivers point toward a series of cultural shifts and illuminate how we are developing new ways of organizing, constructing, and managing knowledge.…

  6. Gaining Campaign Support through Peer Networking: An Impact Analysis of Energy Efficiency Projects in Malaysia

    ERIC Educational Resources Information Center

    Mustafa, Hasrina

    2010-01-01

    This article presents a comprehensive evaluation of the impact of two community projects on energy efficiency held in Malaysia in January 2008. Specifically, the study was undertaken to compare levels of attitudes and practices of energy efficiency between baseline and post-campaign survey; compare electricity consumptions before, one month after,…

  7. Gaining Campaign Support through Peer Networking: An Impact Analysis of Energy Efficiency Projects in Malaysia

    ERIC Educational Resources Information Center

    Mustafa, Hasrina

    2010-01-01

    This article presents a comprehensive evaluation of the impact of two community projects on energy efficiency held in Malaysia in January 2008. Specifically, the study was undertaken to compare levels of attitudes and practices of energy efficiency between baseline and post-campaign survey; compare electricity consumptions before, one month after,…

  8. The energy scaling in a side-pumped ultra-low-magnification unstable resonator by employing a compact master oscillator power amplifier

    NASA Astrophysics Data System (ADS)

    Cho, C. Y.; Huang, Y. P.; Su, K. W.

    2016-10-01

    The energy scaling for a diode-side-pumped passively Q-switched Nd:YAG laser in an ultra-low-magnification unstable convex-concave resonator is investigated. Theoretical analysis and experimental results indicate the fact that the energy scaling is restricted by the increasing of side-pumping sources inside the resonator because of the significant pump-to-mode size mismatching. It is verified that employing the master oscillation power amplifier can effectively enlarge the output pulse energy and improve the beam quality. Up to 60-mJ pulse energy with 17-MW peak power is obtained at a pump energy of 520 mJ. A 1573-nm eye-safe laser emission with pulse energy up to 25 mJ is further attended via the extracavity optical parametric oscillator.

  9. Possible energy gain for a plasma-liner-driven magneto-inertial fusion concept

    SciTech Connect

    Knapp, C. E.; Kirkpatrick, R. C.

    2014-07-15

    A one-dimensional parameter study of a Magneto-Inertial Fusion (MIF) concept indicates that significant gain may be achievable. This concept uses a dynamically formed plasma shell with inwardly directed momentum to drive a magnetized fuel to ignition, which in turn partially burns an intermediate layer of unmagnetized fuel. The concept is referred to as Plasma Jet MIF or PJMIF. The results of an adaptive mesh refinement Eulerian code (Crestone) are compared to those of a Lagrangian code (LASNEX). These are the first published results using the Crestone and LASNEX codes on the PJMIF concept.

  10. Heat gain testing to energy balance protocol. Final report, August 1995-February 1997

    SciTech Connect

    Knappmiller, K.; Schrock, D.

    1997-02-01

    Under sponsorship of the Gas Research Institute, heat gain tests were conducted on gas and electric commercial cooking appliances, applying the American Society for Testing and Materials (ASTM) Standard Test Method for the Performance of Commercial Kitchen Ventilation Systems, F1704-96. The commercial cooking appliances tested in this program were gas and electric: griddles, ranges, convection ovens, charbroilers, and fryers. These appliances were all tested under a wall canopy hood operating at a single exhaust rate appropriate for the particular cooking appliance.

  11. Possible energy gain for a plasma-liner-driven magneto-inertial fusion concept

    NASA Astrophysics Data System (ADS)

    Knapp, C. E.; Kirkpatrick, R. C.

    2014-07-01

    A one-dimensional parameter study of a Magneto-Inertial Fusion (MIF) concept indicates that significant gain may be achievable. This concept uses a dynamically formed plasma shell with inwardly directed momentum to drive a magnetized fuel to ignition, which in turn partially burns an intermediate layer of unmagnetized fuel. The concept is referred to as Plasma Jet MIF or PJMIF. The results of an adaptive mesh refinement Eulerian code (Crestone) are compared to those of a Lagrangian code (LASNEX). These are the first published results using the Crestone and LASNEX codes on the PJMIF concept.

  12. Metabolic requirements of red drum, Sciaenops ocellatus, for protein and energy based on weight gain and body composition.

    PubMed

    McGoogan, B B; Gatlin, D M

    1998-01-01

    Precise formulation of diets that meet but do not greatly exceed nutritional requirements should assist in lowering feed costs for commercial aquaculture of red drum, Sciaenops ocellatus. In this study, protein and energy requirements of red drum for maintenance and maximum gain were determined by feeding a diet containing digestible protein (DP) at 36.5% and 14.2 kJ digestible energy (DE) per gram at various rates for 8 wk in two separate experiments. Changes in weight and whole-body energy and protein were measured and regressed against protein or energy fed using a nonlinear procedure. In the first experiment, juvenile fish [ approximately 3. 4 g initial body weight (BW)] were either starved or fed at one of the following g/(100 g BW.d): 0.5, 1, 2, 4, 6, or 8. The second experiment utilized larger red drum (approximately 5.5 g initial weight), fed 0.75, 1.5, 3, 5, 5.5, 6, 6.5 or 7 g/(100 g BW.d) to confirm and refine results from the first experiment. Based on maintenance of body weight in both experiments, red drum had a protein maintenance requirement of 1.5 and 2.5 g DP/(kg BW.d) whereas estimates based on maintenance of whole-body protein were 0.5 and 2.2 g DP/(kg BW.d). Energy requirements for maintenance of weight and body energy ranged from 58 to 93 and 92 to 97 kJ DE/(kg BW.d), respectively. Protein requirements for maximum weight gain and change in body protein ranged from 20 to 25 g DP/(kg BW.d), whereas energy requirements for maximum weight gain and whole-body deposition ranged from 776 to 958 and 914 to 985 kJ DE/(kg BW.d), respectively. These requirements for maintenance and maximum gain of red drum should assist in formulation of diets for a variety of desired feeding strategies.

  13. Changes in Energy Expenditure with Weight Gain and Weight Loss in Humans.

    PubMed

    Müller, Manfred J; Enderle, Janna; Bosy-Westphal, Anja

    2016-12-01

    Metabolic adaptation to weight changes relates to body weight control, obesity and malnutrition. Adaptive thermogenesis (AT) refers to changes in resting and non-resting energy expenditure (REE and nREE) which are independent from changes in fat-free mass (FFM) and FFM composition. AT differs in response to changes in energy balance. With negative energy balance, AT is directed towards energy sparing. It relates to a reset of biological defence of body weight and mainly refers to REE. After weight loss, AT of nREE adds to weight maintenance. During overfeeding, energy dissipation is explained by AT of the nREE component only. As to body weight regulation during weight loss, AT relates to two different set points with a settling between them. During early weight loss, the first set is related to depleted glycogen stores associated with the fall in insulin secretion where AT adds to meet brain's energy needs. During maintenance of reduced weight, the second set is related to low leptin levels keeping energy expenditure low to prevent triglyceride stores getting too low which is a risk for some basic biological functions (e.g., reproduction). Innovative topics of AT in humans are on its definition and assessment, its dynamics related to weight loss and its constitutional and neuro-endocrine determinants.

  14. Gaining perspective on the water-energy nexus at the community scale.

    PubMed

    Perrone, Debra; Murphy, Jennifer; Hornberger, George M

    2011-05-15

    Water and energy resources are interrelated but their influence on each other is rarely considered. To quantify the water and energy portfolios associated with a community's water-energy nexus (WEN) and the influence of geographic location on resources, we present the WEN tool. The WEN tool quantifies a community's transport (consumed for or lost before delivery) and nexus (energy for water and water for energy) resources so communities can assess their resource flows. In addition, to provide insight into the full range of impacts of water and energy resource acquisition and to frame the influence of geography on resources, we coin the term "urban resource islands". The concept of urban resource islands provides a framework for considering the implication of geography on a community's water and energy resource acquisition and use. The WEN tool and the concept of resource islands can promote communities to think about their hidden resources and integrate such concepts into their sustainability trade-off analyses and policy decisions. In this paper, we use Tucson, Arizona, United States as a case study.

  15. Prediction of genetic gains by selection indices using mixed models in elephant grass for energy purposes.

    PubMed

    Silva, V B; Daher, R F; Araújo, M S B; Souza, Y P; Cassaro, S; Menezes, B R S; Gravina, L M; Novo, A A C; Tardin, F D; Júnior, A T Amaral

    2017-09-27

    Genetically improved cultivars of elephant grass need to be adapted to different ecosystems with a faster growth speed and lower seasonality of biomass production over the year. This study aimed to use selection indices using mixed models (REML/BLUP) for selecting families and progenies within full-sib families of elephant grass (Pennisetum purpureum) for biomass production. One hundred and twenty full-sib progenies were assessed from 2014 to 2015 in a randomized block design with three replications. During this period, the traits dry matter production, the number of tillers, plant height, stem diameter, and neutral detergent fiber were assessed. Families 3 and 1 were the best classified, being the most indicated for selection effect. Progenies 40, 45, 46, and 49 got the first positions in the three indices assessed in the first cut. The gain for individual 40 was 161.76% using Mulamba and Mock index. The use of selection indices using mixed models is advantageous in elephant grass since they provide high gains with the selection, which are distributed among all the assessed traits in the most appropriate situation to breeding programs.

  16. Optimisation of cascaded Yb fiber amplifier chains using numerical-modelling.

    PubMed

    He, F; Price, J H; Vu, K T; Malinowski, A; Sahu, J K; Richardson, D J

    2006-12-25

    We show that it is possible to adapt existing software packages developed originally for modeling telecommunication devices and systems to reliably predict and optimize the performance of high-power Ytterbium-doped fiber amplifier and laser systems. The ready availability of a flexible, user-friendly design tool should be of considerable practical interest to scientists and engineers working with this important new laser technology since Ytterbium amplifier and amplifier cascades are often difficult to optimize experimentally due to the three-level nature of the Ytterbium laser transition. As examples of the utility and accuracy of the software, as well as the complexity of the systems and amplifier properties that can be successfully modeled, we present a comparison of experimental and theoretical results for individual core and cladding pumped amplifiers, and also for an ultra-short pulse four-stage amplifier system optimized both to provide a broad gain bandwidth and to minimize nonlinear effects. We also show how high energy 100 ns pulses with complex user definable temporal profiles can be created in a gain-saturated amplifier by suitable pre-shaping of the low-energy input pulses. Furthermore, with appropriate modifications the same software package can be applied to fiber amplifiers based on other rare-earth elements and glass hosts.

  17. Characterization of SLUG microwave amplifiers

    NASA Astrophysics Data System (ADS)

    Hoi, I.-C.; Zhu, S.; Thorbeck, T.; McDermott, R.; Mutus, J.; Jeffrey, E.; Barends, R.; Chen, Y.; Roushan, P.; Fowler, A.; Sank, D.; White, T.; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Kelly, J.; Megrant, A.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Vainsencher, A.; Wenner, J.; Martinis, J. M.

    2015-03-01

    With the rapid growth of superconducting circuits quantum technology, a near quantum-limited amplifier at GHz frequency is needed to enable high fidelity measurements. We describe such an amplifier, the SQUID based, superconducting low inductance undulatory galvanometer (SLUG) amplifier. We measure the full scattering matrix of the SLUG. In particular, we measure both forward and reverse gain, as well as reflection. We see 15dB forward gain with added noise from one quanta to several quanta. The -1 dB compression point is around -95 dBm, about two orders of magnitude higher than that of typical Josephson parametric amplifiers. With these properties, SLUG is well suited for the high fidelity, simultaneous multiplexed readout of superconducting qubits.

  18. High energy cw-diode pumped Nd:YVO4 regenerative amplifier with efficient second harmonic generation.

    PubMed

    Lührmann, Markus; Theobald, Christian; Wallenstein, Richard; L'huillier, Johannes A

    2009-12-07

    We report on a 888 nm diode-pumped Nd:YVO4 regenerative amplifier with up to 33.7 W output power with a repetition-rate of 20 kHz and an adjustable pulse duration between 217 ps and 1 ns. This setup allowed for efficient second harmonic generation with an efficiency of up to 79%.

  19. Restriction of rapid eye movement sleep during adolescence increases energy gain and metabolic efficiency in young adult rats.

    PubMed

    Ribeiro-Silva, Neila; Nejm, Mariana Bocca; da Silva, Sylvia Maria Affonso; Suchecki, Deborah; Luz, Jacqueline

    2016-02-01

    What is the central question of this study? Sleep curtailment in infancy and adolescence may lead to long-term risk for obesity, but the mechanisms involved have not yet been determined. This study examined the immediate and long-term metabolic effects produced by sleep restriction in young rats. What is the main finding and its importance? Prolonged sleep restriction reduced weight gain (body fat stores) in young animals. After prolonged recovery, sleep-restricted rats tended to save more energy and to store more fat, possibly owing to increased gross food efficiency. This could be the first step to understand this association. Sleep curtailment is associated with obesity and metabolic changes in adults and children. The aim of the present study was to evaluate the immediate and long-term metabolic alterations produced by sleep restriction in pubertal male rats. Male Wistar rats (28 days old) were allocated to a control (CTL) group or a sleep-restricted (SR) group. This was accomplished by the single platform technique for 18 h per day for 21 days. These groups were subdivided into the following four time points for assessment: sleep restriction and 1, 2 and 4 months of recovery. Body weight and food intake were monitored throughout the experiment. At the end of each time period, blood was collected for metabolic profiling, and the carcasses were processed for measurement of body composition and energy balance. During the period of sleep restriction, SR animals consumed less food in the home cages. This group also displayed lower body weight, body fat, triglycerides and glucose levels than CTL rats. At the end of the first month of recovery, despite eating as much as CTL rats, SR animals showed greater energy and body weight gain, increased gross food efficiency and decreased energy expenditure. At the end of the second and fourth months of recovery, the groups were no longer different, except for energy gain and gross food efficiency, which remained higher in SR

  20. Transverse intensity transformation by laser amplifiers

    NASA Astrophysics Data System (ADS)

    Litvin, Igor A.; King, Gary; Collett, Oliver J. P.; Strauss, Hencharl J.

    2015-03-01

    Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping. We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 μm seed laser was amplified in a Ho:YLF bulk amplifier which was being pumped by a 1.89 μm Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.

  1. Low Cost RF Amplifier for Community TV

    NASA Astrophysics Data System (ADS)

    Ch, Syafaruddin; Sasongko, Sudi Mariyanto Al; Made Budi Suksmadana, I.; Mustiko Okta Muvianto, Cahyo; Ariessaputra, Suthami

    2016-01-01

    he capability of television to deliver audio video makes this media become the most effective method to spread information. This paper presents an experiment of RF amplifier design having low-cost design and providing sufficient RF power particularly for community television. The RF amplifier consists of two stages of amplifier. The first stage amplifier was used to leverage output of TV modulator from 11dBm to enable to drive next stage amplifier. CAD simulation and fabrication were run to reach optimum RF amplifier design circuit. The associated circuit was made by determining stability circle, stability gain, and matching impedance. Hence, the average power of first stage RF amplifier was 24.68dBm achieved. The second stage used RF modules which was ready match to 50 ohm for both input and output port. The experiment results show that the RF amplifier may operate at frequency ranging from 174 to 230MHz. The average output power of the 2nd stage amplifier was 33.38 Watt with the overall gain of 20.54dB. The proposed RF amplifier is a cheap way to have a stable RF amplifier for community TV. The total budget for the designed RF amplifier is only a 1/5 compared to local design of final TV amplifier.

  2. 32-GHz Wideband Maser Amplifier

    NASA Technical Reports Server (NTRS)

    Shell, J. S.; Neff, D. E.

    1990-01-01

    High-gain, wideband, microwave amplifier based on ruby cooled by liquid helium. Features include low input equivalent noise temperature and 400-MHz bandwidth. Design basically extension of previous reflected-wave masers built for frequency range of 18 to 26 GHz. Maser amplifier includes eight stages connected in reflected-wave configuration. Particularly useful for detection of weak microwave signals in radio astronomy and communications.

  3. 32-GHz Wideband Maser Amplifier

    NASA Technical Reports Server (NTRS)

    Shell, J. S.; Neff, D. E.

    1990-01-01

    High-gain, wideband, microwave amplifier based on ruby cooled by liquid helium. Features include low input equivalent noise temperature and 400-MHz bandwidth. Design basically extension of previous reflected-wave masers built for frequency range of 18 to 26 GHz. Maser amplifier includes eight stages connected in reflected-wave configuration. Particularly useful for detection of weak microwave signals in radio astronomy and communications.

  4. Operational amplifiers-some misconceptions

    NASA Astrophysics Data System (ADS)

    Summers, M. K.

    1980-03-01

    The simplified theoretical treatments of operational amplifier behaviour found in material for use by teachers and students is often misleading and sometimes inaccurate. The author identifies some of these inadequacies and describes some pedagogical pitfalls which are best avoided. The closed loop gain of an operational amplifier in the inverting configuration taken from the JMB publication Physics (Advanced)-Notes on the Core Syllabus (1978a) is reproduced to act as a focus for discussion.

  5. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    DOE PAGES

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; ...

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, andmore » prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.« less

  6. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    SciTech Connect

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino J.; Black, Jeffrey D.; Marshall, P. W.; Reed, R. A.; McCurdy, M. W.; Weller, R. A.; Pellish, J. A.; Rodbell, K. P.; Gordon, M. S.

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.

  7. High-efficiency multipass Ti:sapphire amplifiers for a continuous-wave single-mode laser.

    PubMed

    Georges, P; Estable, F; Salin, F; Poizat, J P; Grangier, P; Brun, A

    1991-02-01

    We present the amplification of a continuous-wave single-mode ring dye laser in Ti:sapphire. A peak gain of 2 x 10(6) has been obtained in a passive multipass amplifier, which yielded 20-nsec pulses of 0.7-mJ energy at 780 nm. We discuss the advantages of this passive multipass amplifier in comparison with a regenerative amplifier that we have also developed. By second-harmonic generation we obtained high-peak-power UV pulses from the amplified single-mode laser.

  8. Distribution of energy intake throughout the day and weight gain: a population-based cohort study in Spain.

    PubMed

    Hermengildo, Ygor; López-García, Esther; García-Esquinas, Esther; Pérez-Tasigchana, Raúl F; Rodríguez-Artalejo, Fernando; Guallar-Castillón, Pilar

    2016-06-01

    Experimental research suggests that food timing is associated with weight regulation. However, the association between the distribution of energy intake (EI) throughout the day and weight gain in the population is uncertain. A cohort of 4243 individuals (49·9 % men, 50·1 % women) aged ≥18 years was selected in 2008-2010 and followed-up through 2012. At baseline, food consumption for a typical week in the previous year was collected with a validated dietary history, and EI was assessed at six eating occasions: breakfast, mid-morning meal, lunch, mid-afternoon meal, dinner and snacking (at any other moment). Individuals were classified into sex-specific quartiles of %EI for each eating occasion. The cut-off points for increasing quartiles of %EI at lunch were 34·4, 40·8 and 47·7 % in men and 33·2, 39·4 and 46·1 % in women. Weight was self-reported at baseline and at the end of follow-up. During a 3·5-year follow-up, 16·3 % of study participants gained >3 kg. Compared with those in the lowest quartile of %EI at lunch, the multivariate OR of gaining >3 kg was 0·79 (95 % CI 0·63, 0·99) in the second quartile, 0·82 (95 % CI 0·64, 1·04) in the third quartile and 0·62 (95 % CI 0·47, 0·80) in the highest quartile (P trend: 0·001). The association was stronger among women and those with overweight or obesity. No association was found between the %EI at the rest of the eating occasions and weight gain. In conclusion, a higher %EI at lunch was associated with a lower risk of weight gain; this may help weight control through the appropriate distribution of daily EI.

  9. Moderation of antipsychotic-induced weight gain by energy balance gene variants in the RUPP autism network risperidone studies

    PubMed Central

    Nurmi, E L; Spilman, S L; Whelan, F; Scahill, L L; Aman, M G; McDougle, C J; Arnold, L E; Handen, B; Johnson, C; Sukhodolsky, D G; Posey, D J; Lecavalier, L; Stigler, K A; Ritz, L; Tierney, E; Vitiello, B; McCracken, J T

    2013-01-01

    Second-generation antipsychotic exposure, in both children and adults, carries significant risk for excessive weight gain that varies widely across individuals. We queried common variation in key energy balance genes (FTO, MC4R, LEP, CNR1, FAAH) for their association with weight gain during the initial 8 weeks in the two NIMH Research Units on Pediatric Psychopharmacology Autism Network trials (N=225) of risperidone for treatment of irritability in children/adolescents aged 4–17 years with autism spectrum disorders. Variants in the cannabinoid receptor (CNR)-1 promoter (P=1.0 × 10−6), CNR1 (P=9.6 × 10−5) and the leptin (LEP) promoter (P=1.4 × 10−4) conferred robust-independent risks for weight gain. A model combining these three variants was highly significant (P=1.3 × 10−9) with a 0.85 effect size between lowest and highest risk groups. All results survived correction for multiple testing and were not dependent on dose, plasma level or ethnicity. We found no evidence for association with a reported functional variant in the endocannabinoid metabolic enzyme, fatty acid amide hydrolase, whereas body mass index-associated single-nucleotide polymorphisms in FTO and MC4R showed only trend associations. These data suggest a substantial genetic contribution of common variants in energy balance regulatory genes to individual antipsychotic-associated weight gain in children and adolescents, which supersedes findings from prior adult studies. The effects are robust enough to be detected after only 8 weeks and are more prominent in this largely treatment naive population. This study highlights compelling directions for further exploration of the pharmacogenetic basis of this concerning multifactorial adverse event. PMID:23799528

  10. Moderation of antipsychotic-induced weight gain by energy balance gene variants in the RUPP autism network risperidone studies.

    PubMed

    Nurmi, E L; Spilman, S L; Whelan, F; Scahill, L L; Aman, M G; McDougle, C J; Arnold, L E; Handen, B; Johnson, C; Sukhodolsky, D G; Posey, D J; Lecavalier, L; Stigler, K A; Ritz, L; Tierney, E; Vitiello, B; McCracken, J T

    2013-06-25

    Second-generation antipsychotic exposure, in both children and adults, carries significant risk for excessive weight gain that varies widely across individuals. We queried common variation in key energy balance genes (FTO, MC4R, LEP, CNR1, FAAH) for their association with weight gain during the initial 8 weeks in the two NIMH Research Units on Pediatric Psychopharmacology Autism Network trials (N=225) of risperidone for treatment of irritability in children/adolescents aged 4-17 years with autism spectrum disorders. Variants in the cannabinoid receptor (CNR)-1 promoter (P=1.0 × 10(-6)), CNR1 (P=9.6 × 10(-5)) and the leptin (LEP) promoter (P=1.4 × 10(-4)) conferred robust-independent risks for weight gain. A model combining these three variants was highly significant (P=1.3 × 10(-9)) with a 0.85 effect size between lowest and highest risk groups. All results survived correction for multiple testing and were not dependent on dose, plasma level or ethnicity. We found no evidence for association with a reported functional variant in the endocannabinoid metabolic enzyme, fatty acid amide hydrolase, whereas body mass index-associated single-nucleotide polymorphisms in FTO and MC4R showed only trend associations. These data suggest a substantial genetic contribution of common variants in energy balance regulatory genes to individual antipsychotic-associated weight gain in children and adolescents, which supersedes findings from prior adult studies. The effects are robust enough to be detected after only 8 weeks and are more prominent in this largely treatment naive population. This study highlights compelling directions for further exploration of the pharmacogenetic basis of this concerning multifactorial adverse event.

  11. EuropeaN Energy balance Research to prevent excessive weight Gain among Youth (ENERGY) project: Design and methodology of the ENERGY cross-sectional survey

    PubMed Central

    2011-01-01

    Background Obesity treatment is by large ineffective long term, and more emphasis on the prevention of excessive weight gain in childhood and adolescence is warranted. To inform energy balance related behaviour (EBRB) change interventions, insight in the potential personal, family and school environmental correlates of these behaviours is needed. Studies on such multilevel correlates of EBRB among schoolchildren in Europe are lacking. The ENERGY survey aims to (1) provide up-to-date prevalence rates of measured overweight, obesity, self-reported engagement in EBRBs, and objective accelerometer-based assessment of physical activity and sedentary behaviour and blood-sample biomarkers of metabolic function in countries in different regions of Europe, (2) to identify personal, family and school environmental correlates of these EBRBs. This paper describes the design, methodology and protocol of the survey. Method/Design A school-based cross-sectional survey was carried out in 2010 in seven different European countries; Belgium, Greece, Hungary, the Netherlands, Norway, Slovenia, and Spain. The survey included measurements of anthropometrics, child, parent and school-staff questionnaires, and school observations to measure and assess outcomes (i.e. height, weight, and waist circumference), EBRBs and potential personal, family and school environmental correlates of these behaviours including the social-cultural, physical, political, and economic environmental factors. In addition, a selection of countries conducted accelerometer measurements to objectively assess physical activity and sedentary behaviour, and collected blood samples to assess several biomarkers of metabolic function. Discussion The ENERGY survey is a comprehensive cross-sectional study measuring anthropometrics and biomarkers as well as assessing a range of EBRBs and their potential correlates at the personal, family and school level, among 10-12 year old children in seven European countries. This study

  12. Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier for high-energy femtosecond pulses at 1.55 microm.

    PubMed

    Shirakawa, Akira; Ota, Jun; Musha, Mitsuru; Nakagawa, Ken'ichi; Ueda, Ken-Ichi; Folkenberg, Jacob Riis; Broeng, Jes

    2005-02-21

    We report a high-energy femtosecond fiber amplifier based on an air-cladded single-transverse-mode erbium-ytterbium-codoped photonic-crystal fiber with a 26-microm mode-field-diameter. 700-fs, 47-MHz pulses at 1557 nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with 54-kW peak powers without chirped-pulse amplification. A linearly polarized output with an extinction ratio exceeding 42 dB was obtained by double-pass configuration. As an application, supercontinuum spanning from 1000 to 2500 nm was generated by a successive 2-m high-nonlinear fiber with a 140-mW average power.

  13. Light ion beam approach to ICF ignition, gain, and energy production

    SciTech Connect

    Olson, R.; Allshouse, G.; Cook, D.; Lockner, T.; Mazarakis, M.; Olson, C.; Smith, D. ); Peterson, R.; Adler, D.; Bruggink, D.; Englestad, R.; Khater, H.; Kulcinski, G.; Lovell, E.; MacFarlane, J.; Morgahead, E.; Moses, G.; Rutledge, S.; Sawan, M.; Sviatoslalvsky, I.; Wang, P.; Wittenberg, L. )

    1994-10-05

    A review of anticipated achievements in the light ion beam method of the inertial confinement fusion program is presented. They allow to estimate the cost of produced electric energy. It appears to be quite competitive to other fusion reactor designs at the 1000 MWe level and above. (AIP) [copyright] [ital American] [ital Institute] [ital of] [ital Physics] 1994

  14. The effect of simulating weight gain on the energy cost of walking in unimpaired children and children with cerebral palsy.

    PubMed

    Plasschaert, Frank; Jones, Kim; Forward, Malcolm

    2008-12-01

    To examine the effect of simulating weight gain on the energy cost of walking in children with cerebral palsy (CP) compared with unimpaired children. Repeated measures, matched subjects, controlled. University hospital clinical gait and movement analysis laboratory. Children (n=42) with CP and unimpaired children (n=42). Addition of 10% of body mass in weight belt. Energy cost of walking parameters consisting of walking speed, Physiological Cost Index, Total Heart Beat Index, oxygen uptake (VO2), gross oxygen cost, nondimensional net oxygen cost, and net oxygen cost with speed normalized to height were measured by using a breath-by-breath gas analysis system (K4b2) and a light beam timing gate system arranged around a figure 8 track. Two walking trials were performed in random order, with and the other without wearing a weighted belt. Children with CP and their unimpaired counterparts responded in fundamentally different ways to weight gain. The unimpaired population maintained speed and VO2 but the children with CP trended toward a drop in their speed and an increase in their VO2. The oxygen consumption of children with CP showed a greater dependence on mass than the unimpaired group (P=.043). An increase of a relatively small percentage in body mass began to significantly impact the energy cost of walking in children with CP. This result highlights the need for weight control to sustain the level of functional walking in these children.

  15. Fermented Barley Supplementation Modulates the Expression of Hypothalamic Genes and Reduces Energy Intake and Weight Gain in Rats.

    PubMed

    Pichiah, P B Tirupathi; Cho, Suk-Ho; Han, Seong-Kyu; Cha, Youn-Soo

    2016-04-01

    Dietary fiber and proteins are individually known to decrease feeding, but could result greater weight management benefit when both are combined. We hypothesized that supplementing the diet with fermented barley, being rich in both dietary fiber and proteins, could lower energy intake by modulating the mRNA expression level of hypothalamic genes associated with the regulation of feeding behavior and satiety; thereby decreasing body weight gain. To test our hypothesis, four groups of Sprague Dawley rats were arranged in a 2 × 2 factorial design (n = 6), low-fat diet with either guar gum (LFD-G) or fermented barley (LFD-FB) and high-fat diet with either guar gum (HFD-G) or fermented barley (HFD-FB). Using oral gavage, fermented barley was given at a dosage of 1500 mg/kg body weight and guar gum was supplemented in an equivalent quantity to that of the fiber in the fermented barley. After 19 weeks, the fermented barley-supplemented groups showed a significant reduction in energy intake, triglyceride, body weight gain, and serum leptin, compared to the guar gum-supplemented groups in both the low- and high-fat diet groups. Likewise, the anorexigenic gene proopiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART) mRNA level were significantly higher in the fermented barley-supplemented groups compared to the guar gum-supplemented groups in rats fed on both high- and low-fat diets. In conclusion, fermented barley supplementation upregulated hypothalamic POMC/CART, decreased energy intake in both low- and high-fat diet groups, and prevented excessive weight gain in rats.

  16. Energy gain by defect formation: a new tight binding annealed model for a-Si

    NASA Astrophysics Data System (ADS)

    Feldman, Joseph; Bernstein, Noam; Fornari, Marco; Papaconstantopoulos, Dimitris

    2006-03-01

    We have obtained a new structure of a-Si by annealing with QM forces a Wooten CRN type 216 model. The annealing was done for 1.2 ns (1.2 million time steps) and the NRL tight binding method was employed. We obtain the total energy, electronic density of states, and force constants of the model. Whereas the starting model had no coordination defects several were present in the final model. As expected these defects were found to give rise to states in the gap as determined both by charge self-consistent TB calculations and DFT (pseudopotential) calculations, where the latter were performed on related ``relaxed'' models within DFT. The final model was of lower total energy than the starting model, both within the TB method and within the psedopotential method. The normal mode properties based on our force constant determination within TB will also be discussed.

  17. Research and Development of High Energy 2 - Micron Lasers Based on TM: Doped Ceramic Laser Gain Media and TM: Doped Optical Fibers

    DTIC Science & Technology

    2016-07-20

    AFRL-AFOSR-VA-TR-2016-0257 RESEARCH AND DEVELOPMENT OF HIGH ENERGY 2 - MICRON LASERS BASED ON TM: DOPED CERAMIC LASER GAIN MEDIA AND TM: DOPED...2010 to 01/03/2016 4. TITLE AND SUBTITLE RESEARCH AND DEVELOPMENT OF HIGH ENERGY 2 - MICRON LASERS BASED ON TM: DOPED CERAMIC LASER GAIN MEDIA AND...TERMS Development of high energy 2-micron lasers 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 14 19a. NAME OF

  18. Coherent amplified optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Rao, Bin; Chen, Zhongping

    2007-07-01

    A technique to improve the signal-to-noise ratio (SNR) of a high speed 1300 nm swept source optical coherence tomography (SSOCT) system was demonstrated. A semiconductor optical amplifier (SOA) was employed in the sample arm to coherently amplify the weak light back-scattered from sample tissue without increasing laser power illuminated on the sample. The image quality improvement was visualized and quantified by imaging the anterior segment of a rabbit eye at imaging speed of 20,000 A-lines per second. The theory analysis of SNR gain is given followed by the discussion on the technologies that can further improve the SNR gain.

  19. Improved Grid-Array Millimeter-Wave Amplifier

    NASA Technical Reports Server (NTRS)

    Rosenberg, James J.; Rutledge, David B.; Smith, R. Peter; Weikle, Robert

    1993-01-01

    Improved grid-array amplifiers operating at millimeter and submillimeter wavelengths developed for use in communications and radar. Feedback suppressed by making input polarizations orthogonal to output polarizations. Amplifier made to oscillate by introducing some feedback. Several grid-array amplifiers concatenated to form high-gain beam-amplifying unit.

  20. Core body temperature is lower in postmenopausal women than premenopausal women: potential implications for energy metabolism and midlife weight gain.

    PubMed

    Neff, Lisa M; Hoffmann, Mindy E; Zeiss, Dinah M; Lowry, Katherine; Edwards, Monica; Rodriguez, Sarah M; Wachsberg, Kelley N; Kushner, Robert; Landsberg, Lewis

    2016-12-01

    Weight gain during the menopausal transition is common. Although studies have suggested that weight gain is more likely related to aging than menopause, there is a reduction in resting energy expenditure with surgical or natural menopause which is independent of age and changes in body composition. The underlying mechanisms could include a reduction in core body temperature. Data were obtained from two related studies. Sample size was 23 men and 25 women (12 premenopausal,13 postmenopausal). In the Clinical Research Unit, core temperature was measured every minute for 24 hours (CorTemp System,HQ Inc.). Mean 24-hour core body temperature was 0.25 ± 0.06 °C lower in postmenopausal than premenopausal women (p=0.001). Mean 24-hour core temperature was 0.34 ± 0.05 °C lower in men than in premenopausal women (p<0.001). Postmenopausal women, like men, had lower core body temperatures than premenopausal women. This may have implications for midlife weight gain.

  1. A ’Relativistic Mirror’ Experiment with Frequency Tuning and Energy Gain.

    DTIC Science & Technology

    1977-09-01

    enhanced by an even greater factor than the scattered energy : Pr/ ’Pi (1 + ~)4 ~ 4 • In this paper we report an experimental study of electro- magnetic...the artifice of greatly reducing Vph ~ the phase velocity in the wave—plasma interaction region , so that v/v Ph could ap- proach unity. Now , however...nearly a factor of 3. Thus, although the in- tensity profile implies a total reflected power of — 700 kW , the actual value is only known with certainty

  2. Energy gain and spectral tailoring of ion beams using ultra-high intensity laser beams

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Swantusch, Marco; Cerchez, Mirela; Spickermann, Sven; Auorand, Bastian; Wowra, Thomas; Boeker, Juergen; Willi, Oswald

    2015-11-01

    The field of laser driven ion acceleration over the past decade has produced a huge amount of research. Nowadays, several multi-beam facilities with high rep rate system, e.g. ELI, are being developed across the world for different kinds of experiments. The study of interaction dynamics of multiple beams possessing ultra-high intensity and ultra-short pulse duration is of vital importance. Here, we present the first experimental results on ion acceleration using two ultra-high intensity beams. Thanks to the unique capability of Arcturus laser at HHU Düsseldorf, two almost identical, independent beams in laser parameters such as intensity (>1020 W/cm2), pulse duration (30 fs) and contrast (>1010), could be accessed. Both beams are focused onto a 5 μm thin Ti target. While ensuring spatial overlap of the two beams, at relative temporal delay of ~ 50 ps (optimum delay), the proton and carbon ion energies were enhanced by factor of 1.5. Moreover, strong modulation in C4+ions near the high energy cut-off is observed later than the optimum delay for the proton enhancement. This offers controlled tailoring of the spectral content of heavy ions.

  3. Toward the realization of erbium-doped GaN bulk crystals as a gain medium for high energy lasers

    NASA Astrophysics Data System (ADS)

    Sun, Z. Y.; Li, J.; Zhao, W. P.; Lin, J. Y.; Jiang, H. X.

    2016-08-01

    Er-doped GaN (Er:GaN) is a promising candidate as a gain medium for solid-state high energy lasers (HELs) at the technologically important and eye-safe 1.54 μm wavelength window, as GaN has superior thermal properties over traditional laser gain materials such as Nd:YAG. However, the attainment of wafer-scale Er:GaN bulk or quasi-bulk crystals is a prerequisite to realize the full potential of Er:GaN as a gain medium for HELs. We report the realization of freestanding Er:GaN wafers of 2-in. in diameter with a thickness on the millimeter scale. These freestanding wafers were obtained via growth by hydride vapor phase epitaxy in conjunction with a laser-lift-off process. An Er doping level of 1.4 × 1020 atoms/cm3 has been confirmed by secondary ion mass spectrometry measurements. The freestanding Er:GaN wafers exhibit strong photoluminescent emission at 1.54 μm with its emission intensity increasing dramatically with wafer thickness under 980 nm resonant excitation. A low thermal quenching of 10% was measured for the 1.54 μm emission intensity between 10 K and 300 K. This work represents a significant step in providing a practical approach for producing Er:GaN materials with sufficient thicknesses and dimensions to enable the design of gain media in various geometries, allowing for the production of HELs with improved lasing efficiency, atmosphere transmission, and eye-safety.

  4. Toward the realization of erbium-doped GaN bulk crystals as a gain medium for high energy lasers

    SciTech Connect

    Sun, Z. Y.; Li, J.; Zhao, W. P.; Lin, J. Y.; Jiang, H. X.

    2016-08-01

    Er-doped GaN (Er:GaN) is a promising candidate as a gain medium for solid-state high energy lasers (HELs) at the technologically important and eye-safe 1.54 μm wavelength window, as GaN has superior thermal properties over traditional laser gain materials such as Nd:YAG. However, the attainment of wafer-scale Er:GaN bulk or quasi-bulk crystals is a prerequisite to realize the full potential of Er:GaN as a gain medium for HELs. We report the realization of freestanding Er:GaN wafers of 2-in. in diameter with a thickness on the millimeter scale. These freestanding wafers were obtained via growth by hydride vapor phase epitaxy in conjunction with a laser-lift-off process. An Er doping level of 1.4 × 10{sup 20} atoms/cm{sup 3} has been confirmed by secondary ion mass spectrometry measurements. The freestanding Er:GaN wafers exhibit strong photoluminescent emission at 1.54 μm with its emission intensity increasing dramatically with wafer thickness under 980 nm resonant excitation. A low thermal quenching of 10% was measured for the 1.54 μm emission intensity between 10 K and 300 K. This work represents a significant step in providing a practical approach for producing Er:GaN materials with sufficient thicknesses and dimensions to enable the design of gain media in various geometries, allowing for the production of HELs with improved lasing efficiency, atmosphere transmission, and eye-safety.

  5. Calculation of ρ R-parameter and Energy Gain for Aneutronic Fusion in Degenerate P-11 B Plasma

    NASA Astrophysics Data System (ADS)

    Hosseini Motlagh, S. N.; Mohamadi, Sh. S.; Shamsi, R.

    2008-09-01

    Aneutronic fusion reactions are more safe and clean than the other reactions. One of the important candidate for these reactions is P-11 B. This reaction in characteristic conditions creates degenerate plasma. In a Fermi-degenerate plasma, the electronic stopping of a slow ion is smaller than given by the classical formula, because some transitions between the electron states are forbidden. The bremsstrahlung losses are then smaller, so that the nuclear burning of an aneutronic fuel is more efficient. Practical obstacles in this regime that must be overcome before net energy can be realized include the compression of the fuel to an ultra dense state and the creation of a hot spot. In this paper, ρ R parameter (Lawson's criterion) and energy gain for P-11 B are given.

  6. The Influence on Population Weight Gain and Obesity of the Macronutrient Composition and Energy Density of the Food Supply.

    PubMed

    Crino, Michelle; Sacks, Gary; Vandevijvere, Stefanie; Swinburn, Boyd; Neal, Bruce

    2015-03-01

    Rates of overweight and obesity have increased dramatically in all regions of the world over the last few decades. Almost all of the world's population now has ubiquitous access to low-cost, but highly-processed, energy-dense, nutrient-poor food products. These changes in the food supply, rather than decreases in physical activity, are most likely the primary driver of population weight gain and obesity. To-date, the majority of prevention efforts focus on personalised approaches targeting individuals. Population-wide food supply interventions addressing sodium and trans fat reduction have proven highly effective and comparable efforts are now required to target obesity. The evidence suggests that strategies focusing upon reducing the energy density and portion size of foods will be more effective than those targeting specific macronutrients. Government leadership, clearly specified targets, accountability and transparency will be the key to achieving the food supply changes required to address the global obesity epidemic.

  7. The greenGain project - Biomass from landscape conservation and maintenance work for renewable energy production in the EU

    NASA Astrophysics Data System (ADS)

    Clalüna, Aline; Baumgarten, Wibke; García Galindo, Daniel; Lenz, Klaus; Doležal, Jan; De Filippi, Federico; Lorenzo, Joaquín; Montagnoli, Louis

    2017-04-01

    The project greenGain is looking for solutions to increase the energy production with regional and local biomass from landscape conservation and maintenance work, which is performed in the public interest. The relevant resources analysed in the greenGain model regions are, among others, biomass residues from clearing invasive vegetation in marginal agricultural lands in Spain, and residues from abandoned vineyards and olive groves in landscape protected areas in Italy. The main target groups are regional and local players who are responsible for maintenance and conservation work and for the biomass residue management in their regions. Moreover, the focus will be on service providers - including farmers and forest owners, their associations, NGOs, energy providers and consumers. Local companies, municipalities and public authorities are collaborating to identify the still underutilised non-food biomass resources and to discuss the way to integrate them into the local and regional biomass markets. Since the start of the three year project in January 2015, the partners from Italy, Spain, Czech Republic and Germany analysed, among other, the biomass feedstock potential coming from landscape maintenance work, and assessed various technological options to utilise this type of biomass. Further, political, legal and environmental aspects as well as awareness raising and public acceptance actions regarding the energetic use of biomass from public areas were assessed. greenGain also facilitates the exchange between model regions and other similar relevant players in the EU and shares examples of good practice. General guidelines will be prepared to guarantee a wide dissemination to other regions in the EU. Thus, the project shows how to build-up reliable knowledge on local availability of this feedstock and provides know-how concerning planning, harvesting, pre-treatment, storage and sustainable conversion pathways to a wide range of stakeholders in the EU.

  8. Energy-localization-enhanced ground-state cooling of a mechanical resonator from room temperature in optomechanics using a gain cavity

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Long; Liu, Yu-xi

    2017-08-01

    When a gain system is coupled to a loss system, the energy usually flows from the gain system to the loss one. We here present a counterintuitive theory for the ground-state cooling of a mechanical resonator in an optomechanical system via a gain cavity. The energy flows first from the mechanical resonator into the loss cavity and then into the gain cavity and finally localizes there. The energy localization in the gain cavity dramatically enhances the cooling rate of the mechanical resonator. Moreover, we show that an unconventional optical spring effect, e.g., a giant frequency shift and optically induced damping of the mechanical resonator, can be realized. Those feature a precooling-free ground-state cooling, i.e., the mechanical resonator in thermal excitation at room temperature can directly be cooled to its ground state. This cooling approach has potential application in fundamental tests of quantum physics without complicated cryogenic setups.

  9. Time-domain measurement of a self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering

    SciTech Connect

    Marcus, G.; Rosenzweig, J. B.; Artioli, M.; Ciocci, F.; Del Franco, M.; Giannessi, L.; Petralia, A.; Quattromini, M.; Bacci, A.; Bellaveglia, M.; Chiadroni, E.; Di Pirro, G.; Ferrario, M.; Filippetto, D.; Gatti, G.; Rossi, A. R.; Cianchi, A.; Labat, M.; Mostacci, A.; Petrillo, V.; and others

    2012-09-24

    We report, with an unequivocal time-domain measurement, that an appropriately chosen undulator taper can compensate for an electron beam longitudinal energy-chirp in a free-electron laser amplifier, leading to the generation of single-spike radiation close to the Fourier limit. The measurements were taken using the frequency-resolved optical gating technique by employing an advanced transient-grating diagnostic geometry. The reconstructed longitudinal radiation characteristics are compared in detail to prediction from time-dependent three-dimensional simulations.

  10. MW peak-power, mJ pulse energy, multi-kHz repetition rate pulses from Yb-doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Di Teodoro, Fabio; Brooks, Christopher D.

    2006-02-01

    We report on pulsed fiber-based sources generating high peak and average powers in beams of excellent spectral/spatial quality. In the first setup, a ~10-kHz pulse repetition rate (PRR), 1ns-pulse, Q-switched microlaser seeded a dual-stage amplifier featuring a 40-μm-core Yb-doped photonic-crystal fiber (PCF) as the power amplifier. From this amplifier, we obtained diffraction-limited (M2 = 1.05), ~1ns pulses of 1.1mJ energy, ~1.1MW peak power, ~10.2W average-power, spectral linewidth ~9GHz, negligible nonlinearities, and slope efficiency >73%. In the second setup, we replaced the seed source with a shorter-pulse (<500ps) microchip laser of PRR ~13.4 kHz and obtained diffraction-limited (M2=1.05), ~450ps pulses of energy >0.7mJ, peak power in excess of 1.5 MW, average power ~9.5W, spectral linewidth <35 GHz. To show further power scaling, these pulses were amplified in a 140-μmcore Yb-doped fiber, which yielded multimode (M2 ~ 9), 2.2mJ-energy, 30-W average-power pulses of peak power in excess of 4.5MW, the highest ever obtained in a fiber source, to our knowledge. In the third setup, an Yb-doped, 70μmcore, intrinsically single-mode photonic-crystal rod was used to generate diffraction-limited (M2 ~ 1.1), ~10kHz PRR, ~1ns pulses of 2.05mJ energy, >2 MW peak-power (the highest ever reported in a diffraction-limited fiber source), ~20W average-power, ~13 GHz spectral linewidth, and spectral signal-to-noise ratio >50 dB. Finally, a single polarization large-core Yb-doped PCF was used to demonstrate high-peak-power harmonic generation. We obtained ~1ns pulses of peak powers >410 kW in the green (531nm) and >190kW in the UV (265.5 nm).

  11. Transverse pumped laser amplifier architecture

    DOEpatents

    Bayramian, Andrew James; Manes, Kenneth R.; Deri, Robert; Erlandson, Alvin; Caird, John; Spaeth, Mary L.

    2015-05-19

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  12. Transverse pumped laser amplifier architecture

    DOEpatents

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

    2013-07-09

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  13. Transverse Bragg resonance laser amplifier.

    PubMed

    Yariv, Amnon; Xu, Yong; Mookherjea, Shayan

    2003-02-01

    We propose and analyze a new type of optical amplifier that is formed by addition of gain in the periodic cladding of a transverse Bragg resonance waveguide [Opt. Lett. 27, 936 (2002)]. Using the coupled-wave formalism, we calculate the mode profiles, the exponential gain constant, and, for comparison, the gain enhancement compared with those of conventional semiconductor optical amplifiers. In contrast with coupled-mode theory, in one-dimensional structures (e.g., the distributed-feedback laser) the exponential gain constant in the longitudinal direction is involved in both longitudinal and transverse confinement, and its solution has to be achieved self-consistently, together with the quantized guiding channel width.

  14. Functional gains in energy and cell metabolism after TSPO gene insertion

    PubMed Central

    Chin, David Y.; Hatty, Claire R.; Chan, Ronald H. Y.

    2017-01-01

    ABSTRACT Recent loss-of-function studies in tissue-specific as well as global Tspo (Translocator Protein 18 kDa) knockout mice have not confirmed its long assumed indispensability for the translocation of cholesterol across the mitochondrial inter-membrane space, a rate-limiting step in steroid biosynthesis. Instead, recent studies in global Tspo knockout mice indicate that TSPO may play a more fundamental role in cellular bioenergetics, which may include the indirect down-stream regulation of transport or metabolic functions. To examine whether overexpression of the TSPO protein alters the cellular bioenergetic profile, Jurkat cells with low to absent endogenous expression were transfected with a TSPO construct to create a stable cell line with de novo expression of exogenous TSPO protein. Expression of TSPO was confirmed by RT-qPCR, radioligand binding with [3H]PK11195 and immunocytochemistry with a TSPO antibody. We demonstrate that TSPO gene insertion causes increased transcription of genes involved in the mitochondrial electron transport chain. Furthermore, TSPO insertion increased mitochondrial ATP production as well as cell excitability, reflected in a decrease in patch clamp recorded rectified K channel currents. These functional changes were accompanied by an increase in cell proliferation and motility, which were inhibited by PK11195, a selective ligand for TSPO. We suggest that TSPO may serve a range of functions that can be viewed as downstream regulatory effects of its primary, evolutionary conserved role in cell metabolism and energy production. PMID:28103132

  15. Mineral carbonation: energy costs of pretreatment options and insights gained from flow loop reaction studies

    SciTech Connect

    Penner, Larry R.; O'Connor, William K.; Dahlin, David C.; Gerdemann, Stephen J.; Rush, Gilbert E.

    2004-01-01

    Sequestration of carbon as a stable mineral carbonate has been proposed to mitigate environmental concerns that carbon dioxide may with time escape from its sequestered matrix using alternative sequestration technologies. A method has been developed to prepare stable carbonate products by reacting CO2 with magnesium silicate minerals in aqueous bicarbonate/chloride media at high temperature and pressure. Because this approach is inherently expensive due to slow reaction rates and high capital costs, studies were conducted to improve the reaction rates through mineral pretreatment steps and to cut expenses through improved reactor technology. An overview is given for the estimated cost of the process including sensitivity to grinding and heating as pretreatment options for several mineral feedstocks. The energy costs are evaluated for each pretreatment in terms of net carbon avoided. New studies with a high-temperature, high-pressure flow-loop reactor have yielded information on overcoming kinetic barriers experienced with processing in stirred autoclave reactors. Repeated tests with the flow-loop reactor have yielded insights on wear and failure of system components, on challenges to maintain and measure flow, and for better understanding of the reaction mechanism.

  16. Functional gains in energy and cell metabolism after TSPO gene insertion.

    PubMed

    Liu, Guo-Jun; Middleton, Ryan J; Kam, Winnie Wai-Ying; Chin, David Y; Hatty, Claire R; Chan, Ronald H Y; Banati, Richard B

    2017-03-04

    Recent loss-of-function studies in tissue-specific as well as global Tspo (Translocator Protein 18 kDa) knockout mice have not confirmed its long assumed indispensability for the translocation of cholesterol across the mitochondrial inter-membrane space, a rate-limiting step in steroid biosynthesis. Instead, recent studies in global Tspo knockout mice indicate that TSPO may play a more fundamental role in cellular bioenergetics, which may include the indirect down-stream regulation of transport or metabolic functions. To examine whether overexpression of the TSPO protein alters the cellular bioenergetic profile, Jurkat cells with low to absent endogenous expression were transfected with a TSPO construct to create a stable cell line with de novo expression of exogenous TSPO protein. Expression of TSPO was confirmed by RT-qPCR, radioligand binding with [3H]PK11195 and immunocytochemistry with a TSPO antibody. We demonstrate that TSPO gene insertion causes increased transcription of genes involved in the mitochondrial electron transport chain. Furthermore, TSPO insertion increased mitochondrial ATP production as well as cell excitability, reflected in a decrease in patch clamp recorded rectified K channel currents. These functional changes were accompanied by an increase in cell proliferation and motility, which were inhibited by PK11195, a selective ligand for TSPO. We suggest that TSPO may serve a range of functions that can be viewed as downstream regulatory effects of its primary, evolutionary conserved role in cell metabolism and energy production.

  17. System parameters germane to relativistic klystron amplifiers: how the utility of pulse energy depends on pulse duration, the target, and the atmosphere

    NASA Astrophysics Data System (ADS)

    Myers, John M.

    1994-05-01

    Relativistic klystron amplifiers (RKAs) at a variety of carrier wavelengths and pulse durations appear feasible to supply microwave pulses to an array of antennas acting as a beam weapon against targets at or above 100 km in altitude. In order to avoid voltage breakdown in the atmosphere, the array area must be large enough to converge the beam, producing a higher energy flux on target than at intermediate altitudes susceptible to breakdown. The area required depends on the physics of atmospheric ionization and on the pulse duration and the carrier wavelength of the RKA. A quantitative statement of the dependence of array area on relevant parameters is presented. The energy per RKA pulse that is usable without delay lines is determined here as a function of RKA pulse duration and wavelength. Changing the pulse length from 160 ns to 1 microsecond(s) and shortening the wavelength raise the energy usable without delay lines by a factor of 1000.

  18. Extremes of weight gain and weight loss with detailed assessments of energy balance: Illustrative case studies and clinical recommendations.

    PubMed

    Falck, Ryan S; Shook, Robin P; Hand, Gregory A; Lavie, Carl J; Blair, Steven N

    2015-04-01

    Extreme weight changes, or changes in weight greater than 10 kg within a 2-year period, can be caused by numerous factors that are much different than typical weight fluctuations. This paper uses two interesting cases of extreme weight change (a female who experienced extreme weight gain and a male who experienced extreme weight loss) from participants in the Energy Balance Study to illustrate the physiological and psychosocial variables associated with the weight change over a 15-month period, including rigorous assessments of energy intake, physical activity (PA) and energy expenditure, and body composition. In addition, we provide a brief review of the literature regarding the relationship between energy balance (EB) and weight change, as well as insight into proper weight management strategies. The case studies presented here are then placed in the context of the literature regarding EB and weight change. This report further supports previous research on the importance of regular doses of PA for weight maintenance, and that even higher volumes of PA are necessary for weight loss. Practitioners should emphasize the importance of PA to their patients and take steps to monitor their patients' involvement in PA.

  19. Dye laser traveling wave amplifier

    NASA Technical Reports Server (NTRS)

    Davidson, F.; Hohman, J.

    1984-01-01

    A flashlamp pumped dye laser suitable for use as a single stage amplifier is described. Particular emphasis is placed on the efforts to increase output pulse energy and improve the temporal profile of the injected pulse. By using high power thin film polarizers, output energies reach from 4 to 45 mJ. Various dispersive elements are used to develop an amplified pulse with an extremely clean temporal profile.

  20. Power enhancement of a Rubidium vapor laser with a master oscillator power amplifier.

    PubMed

    Hostutler, David A; Klennert, Wade L

    2008-05-26

    A master oscillator power amplifier (MOPA) with variable amplifier gain lengths was built to demonstrate power enhancement of an alkali vapor laser. A small signal gain of 0.91 / cm for two different gain lengths was observed. For a 2 cm long amplifier gain length an amplification of 7.9 dB was observed.

  1. Yb:YAG single-crystal fiber amplifiers for picosecond lasers using the divided pulse amplification technique.

    PubMed

    Lesparre, Fabien; Gomes, Jean Thomas; Délen, Xavier; Martial, Igor; Didierjean, Julien; Pallmann, Wolfgang; Resan, Bojan; Druon, Frederic; Balembois, François; Georges, Patrick

    2016-04-01

    A two-stage master-oscillator power-amplifier (MOPA) system based on Yb:YAG single-crystal-fiber (SCF) technology and designed for high peak power is studied to significantly increase the pulse energy of a low-power picosecond laser. The first SCF amplifier has been designed for high gain. Using a gain medium optimized in terms of doping concentration and length, an optical gain of 32 dB has been demonstrated. The second amplifier stage designed for high energy using the divided pulse technique allows us to generate a recombined output pulse energy of 2 mJ at 12.5 kHz with a pulse duration of 6 ps corresponding to a peak power of 320 MW. Average powers ranging from 25 to 55 W with repetition rates varying from 12.5 to 500 kHz have been demonstrated.

  2. A single supply biopotential amplifier.

    PubMed

    Spinelli, E M; Martinez, N H; Mayosky, M A

    2001-04-01

    A biopotential amplifier for single supply operation is presented. It uses a Driven Right Leg Circuit (DRL) to drive the patient's body to a DC common mode voltage, centering biopotential signals with respect to the amplifier's input voltage range. This scheme ensures proper range operation when a single power supply is used. The circuit described is especially suited for low consumption, battery-powered applications, requiring a single battery and avoiding switching voltage inverters to achieve dual supplies. The generic circuit is described and, as an example, a biopotential amplifier with a gain of 60 dB and a DC input range of +/-200 mV was implemented using low power operational amplifiers. A Common Mode Rejection Ratio (CMRR) of 126 dB at 50 Hz was achieved without trimming.

  3. Optimization of plasma amplifiers

    DOE PAGES

    Sadler, James D.; Trines, Raoul M. G. M.; Tabak, Max; ...

    2017-05-24

    Here, plasma amplifiers offer a route to side-step limitations on chirped pulse amplification and generate laser pulses at the power frontier. They compress long pulses by transferring energy to a shorter pulse via the Raman or Brillouin instabilities. We present an extensive kinetic numerical study of the three-dimensional parameter space for the Raman case. Further particle-in-cell simulations find the optimal seed pulse parameters for experimentally relevant constraints. The high-efficiency self-similar behavior is observed only for seeds shorter than the linear Raman growth time. A test case similar to an upcoming experiment at the Laboratory for Laser Energetics is found tomore » maintain good transverse coherence and high-energy efficiency. Effective compression of a 10kJ, nanosecond-long driver pulse is also demonstrated in a 15-cm-long amplifier.« less

  4. Optimization of plasma amplifiers

    NASA Astrophysics Data System (ADS)

    Sadler, James D.; Trines, Raoul M. Â. G. Â. M.; Tabak, Max; Haberberger, Dan; Froula, Dustin H.; Davies, Andrew S.; Bucht, Sara; Silva, Luís O.; Alves, E. Paulo; Fiúza, Frederico; Ceurvorst, Luke; Ratan, Naren; Kasim, Muhammad F.; Bingham, Robert; Norreys, Peter A.

    2017-05-01

    Plasma amplifiers offer a route to side-step limitations on chirped pulse amplification and generate laser pulses at the power frontier. They compress long pulses by transferring energy to a shorter pulse via the Raman or Brillouin instabilities. We present an extensive kinetic numerical study of the three-dimensional parameter space for the Raman case. Further particle-in-cell simulations find the optimal seed pulse parameters for experimentally relevant constraints. The high-efficiency self-similar behavior is observed only for seeds shorter than the linear Raman growth time. A test case similar to an upcoming experiment at the Laboratory for Laser Energetics is found to maintain good transverse coherence and high-energy efficiency. Effective compression of a 10 kJ , nanosecond-long driver pulse is also demonstrated in a 15-cm-long amplifier.

  5. Novel operation of semiconductor optical amplifier (SOA) for optoelectronic applications

    SciTech Connect

    DiJaili, S.P.

    1996-03-18

    A new effect is demonstrated that can enable all-optical logic at ultrafast speeds using semiconductor optical amplifier technology. This effect is called gain-dependent-time-shift. There may be many opportunities for growth in optical information processing systems using this effect. Modeling results were used to predict the existence of this effect. The experimental demonstration confirmed the existence of the gain-dependent-time-shift. It is predicted that an ultrafast all-optical switch with switching energies of several femtojoules, switching times of sub-100 fsec, low power, and monolithically integrable is possible.

  6. Dual-range linearized transimpedance amplifier system

    DOEpatents

    Wessendorf, Kurt O.

    2010-11-02

    A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).

  7. Amplified spontaneous emission measurement of a line-narrowed, tunable, Ti:Al2O3 amplifier using rubidium absorption

    NASA Technical Reports Server (NTRS)

    Barnes, James C.; Barnes, Norman P.; Lockard, George E.; Cross, Patricia L.

    1989-01-01

    Amplified spontaneous emission, ASE, generated by a Ti:Al2O3 laser amplifier has been measured as a function of pump energy, and thus gain, using the atomic absorption of rubidium, Rb, gas at 0.780 micron. By tuning the Ti:Al2O3 laser, the Rb cell could selectively absorb the narrow spectral bandwidth laser radiation while transmitting the wide spectral bandwidth ASE. Transmission of laser amplifier pulses through a Rb absorption cell, measured at various temperatures, thus allows the measurement of the weak ASE in the vicinity of the strong laser pulse. A model for the transmission of Rb as a function of temperature and wavelength has been developed. The measured transmissions are in good agreement with the transmission model predictions.

  8. Hypothalamic over-expression of VGF in the Siberian hamster increases energy expenditure and reduces body weight gain

    PubMed Central

    Brameld, John M.; Hill, Phil; Cocco, Cristina; Noli, Barbara; Ferri, Gian-Luca; Barrett, Perry; Ebling, Francis J. P.; Jethwa, Preeti H.

    2017-01-01

    VGF (non-acronymic) was first highlighted to have a role in energy homeostasis through experiments involving dietary manipulation in mice. Fasting increased VGF mRNA in the Arc and levels were subsequently reduced upon refeeding. This anabolic role for VGF was supported by observations in a VGF null (VGF-/-) mouse and in the diet-induced and gold-thioglucose obese mice. However, this anabolic role for VGF has not been supported by a number of subsequent studies investigating the physiological effects of VGF-derived peptides. Intracerebroventricular (ICV) infusion of TLQP-21 increased resting energy expenditure and rectal temperature in mice and protected against diet-induced obesity. Similarly, ICV infusion of TLQP-21 into Siberian hamsters significantly reduced body weight, but this was due to a decrease in food intake, with no effect on energy expenditure. Subsequently NERP-2 was shown to increase food intake in rats via the orexin system, suggesting opposing roles for these VGF-derived peptides. Thus to further elucidate the role of hypothalamic VGF in the regulation of energy homeostasis we utilised a recombinant adeno-associated viral vector to over-express VGF in adult male Siberian hamsters, thus avoiding any developmental effects or associated functional compensation. Initially, hypothalamic over-expression of VGF in adult Siberian hamsters produced no effect on metabolic parameters, but by 12 weeks post-infusion hamsters had increased oxygen consumption and a tendency to increased carbon dioxide production; this attenuated body weight gain, reduced interscapular white adipose tissue and resulted in a compensatory increase in food intake. These observed changes in energy expenditure and food intake were associated with an increase in the hypothalamic contents of the VGF-derived peptides AQEE, TLQP and NERP-2. The complex phenotype of the VGF-/- mice is a likely consequence of global ablation of the gene and its derived peptides during development, as well

  9. Hypothalamic over-expression of VGF in the Siberian hamster increases energy expenditure and reduces body weight gain.

    PubMed

    Lewis, Jo E; Brameld, John M; Hill, Phil; Cocco, Cristina; Noli, Barbara; Ferri, Gian-Luca; Barrett, Perry; Ebling, Francis J P; Jethwa, Preeti H

    2017-01-01

    VGF (non-acronymic) was first highlighted to have a role in energy homeostasis through experiments involving dietary manipulation in mice. Fasting increased VGF mRNA in the Arc and levels were subsequently reduced upon refeeding. This anabolic role for VGF was supported by observations in a VGF null (VGF-/-) mouse and in the diet-induced and gold-thioglucose obese mice. However, this anabolic role for VGF has not been supported by a number of subsequent studies investigating the physiological effects of VGF-derived peptides. Intracerebroventricular (ICV) infusion of TLQP-21 increased resting energy expenditure and rectal temperature in mice and protected against diet-induced obesity. Similarly, ICV infusion of TLQP-21 into Siberian hamsters significantly reduced body weight, but this was due to a decrease in food intake, with no effect on energy expenditure. Subsequently NERP-2 was shown to increase food intake in rats via the orexin system, suggesting opposing roles for these VGF-derived peptides. Thus to further elucidate the role of hypothalamic VGF in the regulation of energy homeostasis we utilised a recombinant adeno-associated viral vector to over-express VGF in adult male Siberian hamsters, thus avoiding any developmental effects or associated functional compensation. Initially, hypothalamic over-expression of VGF in adult Siberian hamsters produced no effect on metabolic parameters, but by 12 weeks post-infusion hamsters had increased oxygen consumption and a tendency to increased carbon dioxide production; this attenuated body weight gain, reduced interscapular white adipose tissue and resulted in a compensatory increase in food intake. These observed changes in energy expenditure and food intake were associated with an increase in the hypothalamic contents of the VGF-derived peptides AQEE, TLQP and NERP-2. The complex phenotype of the VGF-/- mice is a likely consequence of global ablation of the gene and its derived peptides during development, as well

  10. GLP-1(32-36)amide Pentapeptide Increases Basal Energy Expenditure and Inhibits Weight Gain in Obese Mice.

    PubMed

    Tomas, Eva; Stanojevic, Violeta; McManus, Karen; Khatri, Ashok; Everill, Paul; Bachovchin, William W; Habener, Joel F

    2015-07-01

    The prevalence of obesity-related diabetes is increasing worldwide. Here we report the identification of a pentapeptide, GLP-1(32-36)amide (LVKGRamide), derived from the glucoincretin hormone GLP-1, that increases basal energy expenditure and curtails the development of obesity, insulin resistance, diabetes, and hepatic steatosis in diet-induced obese mice. The pentapeptide inhibited weight gain, reduced fat mass without change in energy intake, and increased basal energy expenditure independent of physical activity. Analyses of tissues from peptide-treated mice reveal increased expression of UCP-1 and UCP-3 in brown adipose tissue and increased UCP-3 and inhibition of acetyl-CoA carboxylase in skeletal muscle, findings consistent with increased fatty acid oxidation and thermogenesis. In palmitate-treated C2C12 skeletal myotubes, GLP-1(32-36)amide activated AMPK and inhibited acetyl-CoA carboxylase, suggesting activation of fat metabolism in response to energy depletion. By mass spectroscopy, the pentapeptide is rapidly formed from GLP-1(9-36)amide, the major form of GLP-1 in the circulation of mice. These findings suggest that the reported insulin-like actions of GLP-1 receptor agonists that occur independently of the GLP-1 receptor might be mediated by the pentapeptide, and the previously reported nonapeptide (FIAWLVKGRamide). We propose that by increasing basal energy expenditure, GLP-1(32-36)amide might be a useful treatment for human obesity and associated metabolic disorders. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  11. Ultrastable fiber amplifier delivering 145-fs pulses with 6-μJ energy at 10-MHz repetition rate.

    PubMed

    Wunram, Marcel; Storz, Patrick; Brida, Daniele; Leitenstorfer, Alfred

    2015-03-01

    A high-power femtosecond Yb:fiber amplifier operating with exceptional noise performance and long-term stability is demonstrated. It generates a 10-MHz train of 145-fs pulses at 1.03 μm with peak powers above 36 MW. The system features a relative amplitude noise of 1.5·10⁻⁶  Hz(-1/2) at 1 MHz and drifts of the 60-W average power below 0.3% over 72 hours of continuous operation. The passively phase-stable Er:fiber seed system provides ultrabroadband pulses that are synchronized at a repetition rate of 40 MHz. This combination aims at new schemes for sensitive experiments in ultrafast scientific applications.

  12. ON THE COMPUTATION OF PHASE AND ENERGY GAIN FOR A THIN-LENS RF GAP USING A GENERAL FIELD PROFILE

    SciTech Connect

    Allen, Christopher K

    2017-01-01

    The thin-lens representation for an RF accelerating gap has been well developed and is documented by Lapostolle [5], Weiss [6], Wangler [14], and others [9], [10]. These models assume that the axial electric field is both centered and symmetric so it has a cosine expansion. Presented here is a model that considers general axial fields. Both the cosine and sine transit time factors are required plus their Hilbert transforms. The combination yields a complex Hamiltonian rotating in the complex plane with the synchronous phase. The phase and energy gains are computed in the pre-gap and post-gap regions then aligned with asymptotic values of wave number. Derivations are outlined, examples are shown, and simulations presented.

  13. A THEORY FOR BROADBAND VARACTOR PARAMETRIC AMPLIFIERS

    DTIC Science & Technology

    This thesis is concerned with the development of a general and rigorous broadbanding theory for varactor parametric amplifiers . Fundamental gain...bandwidth limitations of a varactor parametric amplifier are obtained which are independent of the equalizer. Results obtained in this theory lead to the...design and synthesis of broadband varactor parametric amplifiers . The circuit considered in this thesis is that of linear variable capacitors embedded

  14. The Microstrip DC SQUID Amplifier

    NASA Astrophysics Data System (ADS)

    Mück, Michael

    2000-03-01

    We have developed an extremely sensitive rf amplifier based on the dc superconducting quantum interference device (dc SQUID). Unlike a conventional semiconductor amplifier, a SQUID can be cooled to ultra low temperatures (300 mK or less) and thus potentially achieve a much lower noise temperature. In a conventional SQUID amplifier, where the integrated input coil is operated as a lumped element, parasitic capacitance between the coil and the SQUID washer limits the frequency up to which a substantial gain can be achieved to a few hundred MHz. This problem can be circumvented by operating the input coil of the SQUID as a microstrip resonator: instead of connecting the input signal between the two ends of the coil, it is connected between the SQUID washer and one end of the coil; the other end is left open. Such amplifiers have gains of 20 dB or more at frequencies up to 1.5 GHz. The resonant nature of the input circuit limits the -3 dB bandwidth of the amplifier to at most 100 MHz. The resonant frequency of the microstrip can be tuned, however, by means of a varactor diode connected across the otherwise open end of the resonator. The noise temperature of microstrip SQUID amplifiers was measured to be between 0.5 K ± 0.3 K at a resonant frequency of 80 MHz and 1.6 K ± 1.2 K at 1 GHz. An even lower noise temperature can be achieved by cooling the SQUID to about 0.4 K. In this case, a noise temperature of 100 mK ± 20 mK was achieved at 90 MHz, and of about 120 ± 100 mK at 440 MHz. The gain of the SQUID amplifier is sensitive to changes of the static magnetic flux through the SQUID. In order to prevent low frequency magnetic noise from changing the amplifier gain, we developed a directly coupled flux-locked loop which stabilizes the static flux bias of the SQUID. Finally, although the maximum output voltage of the SQUID amplifier is relatively small, two-tone intermodulation measurements show an intermodulation-free dynamic range of nearly 50 dB in a bandwidth of

  15. High temperature charge amplifier for geothermal applications

    DOEpatents

    Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.

    2015-12-08

    An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.

  16. Tester periodically registers dc amplifier characteristics

    NASA Technical Reports Server (NTRS)

    Cree, D.; Wenzel, G. E.

    1966-01-01

    Motor-driven switcher-recorder periodically registers the zero drift and gain drift signals of a dc amplifier subjected to changes in environment. A time coding method is used since several measurements are shared on a single recorder trace.

  17. High energy, 1572.3 nm pulses for CO2 LIDAR from a polarization-maintaining, very-large-mode-area, Er-doped fiber amplifier.

    PubMed

    Nicholson, J W; DeSantolo, A; Yan, M F; Wisk, P; Mangan, B; Puc, G; Yu, A W; Stephen, M A

    2016-08-22

    We demonstrate the first polarization-maintaining, very-large-mode-area, Er-doped fiber amplifier with ~1100 μm2 effective area. The amplifier is core pumped by a Raman fiber laser and is used to generate single-frequency, one-microsecond, pulses with pulse energy of 541 μJ, peak power of 700 W, M2 of 1.1, and polarization extinction > 20 dB. The amplifier operates at 1572.3 nm, a wavelength useful for trace atmospheric CO2 detection.

  18. First pulse effect self-suppression picosecond regenerative amplifier (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Fan, Haitao; Chang, Liang; Zhang, Yi; Yao, Siyi; Lu, Wei; Yang, Xiaohong

    2017-03-01

    First pulse effect, commonly seen in nanosecond cavity-dumped lasers and picosecond regenerative amplifiers, not only leads to degradation of processing quality, but also acts as potential threat to optical switching elements. Several methods have been developed to suppress that effect, including electronic controls, polarization controls, and diffraction controls. We present a new way for first pulse self-suppression without any additional components. By carefully arranging the cavity mirror of a regenerative amplifier, we realized `parasitic lasing like' radiation. When the regenerative amplifier works in `operation ready' status, the parasitic lasing occurs and prevents the gain crystal from saturation. When the regenerative amplifier starts working and amplifying pulses, the first pulse in a pulse train will not get much more gain and energy than pulses following it. As parasitic lasing disappears at the same time, the average output power of the amplifier does not significantly reduce. This cost effective method does not require any additional component. In addition, as it is not polarization dependent, this method is widely suitable for different kinds of regenerative amplifiers. It's the easiest and cheapest way to suppress first pulse effect, to the best of our knowledge.

  19. Health and productivity gains from better indoor environments and their implications for the U.S. Department of Energy

    SciTech Connect

    Fisk, William J.

    2000-10-01

    A substantial portion of the US population suffers frequently from communicable respiratory illnesses, allergy and asthma symptoms, and sick building syndrome symptoms. We now have increasingly strong evidence that changes in building design, operation, and maintenance can significantly reduce these illnesses. Decreasing the prevalence or severity of these health effects would lead to lower health care costs, reduced sick leave, and shorter periods of illness-impaired work performance, resulting in annual economic benefits for the US in the tens of billions of dollars. Increasing the awareness of these potential health and economic gains, combined with other factors, could help bring about a shift in the way we design, construct, operate, and occupy buildings. The current goal of providing marginally adequate indoor environments could be replaced by the goal of providing indoor environments that maximize the health, satisfaction, and performance of building occupants. Through research and technology transfer, DOE and its contractors are well positioned to help stimulate this shift in practice and, consequently, improve the health and economic well-being of the US population. Additionally, DOE's energy-efficiency interests would be best served by a program that prepares for the potential shift, specifically by identifying and promoting the most energy-efficient methods of improving the indoor environment. The associated research and technology transfer topics of particular relevance to DOE are identified and discussed.

  20. Real Time Calibration Method for Signal Conditioning Amplifiers

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J. (Inventor); Mata, Carlos T. (Inventor); Eckhoff, Anthony (Inventor); Perotti, Jose (Inventor); Lucena, Angel (Inventor)

    2004-01-01

    A signal conditioning amplifier receives an input signal from an input such as a transducer. The signal is amplified and processed through an analog to digital converter and sent to a processor. The processor estimates the input signal provided by the transducer to the amplifier via a multiplexer. The estimated input signal is provided as a calibration voltage to the amplifier immediately following the receipt of the amplified input signal. The calibration voltage is amplified by the amplifier and provided to the processor as an amplified calibration voltage. The amplified calibration voltage is compared to the amplified input signal, and if a significant error exists, the gain and/or offset of the amplifier may be adjusted as necessary.

  1. Real Time Calibration Method for Signal Conditioning Amplifiers

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J. (Inventor); Mata, Carlos T. (Inventor); Eckhoff, Anthony (Inventor); Perotti, Jose (Inventor); Lucena, Angel (Inventor)

    2004-01-01

    A signal conditioning amplifier receives an input signal from an input such as a transducer. The signal is amplified and processed through an analog to digital converter and sent to a processor. The processor estimates the input signal provided by the transducer to the amplifier via a multiplexer. The estimated input signal is provided as a calibration voltage to the amplifier immediately following the receipt of the amplified input signal. The calibration voltage is amplified by the amplifier and provided to the processor as an amplified calibration voltage. The amplified calibration voltage is compared to the amplified input signal, and if a significant error exists, the gain and/or offset of the amplifier may be adjusted as necessary.

  2. Optical amplifiers for coherent lidar

    NASA Technical Reports Server (NTRS)

    Fork, Richard

    1996-01-01

    We examine application of optical amplification to coherent lidar for the case of a weak return signal (a number of quanta of the return optical field close to unity). We consider the option that has been explored to date, namely, incorporation of an optical amplifier operated in a linear manner located after reception of the signal and immediately prior to heterodyning and photodetection. We also consider alternative strategies where the coherent interaction, the nonlinear processes, and the amplification are not necessarily constrained to occur in the manner investigated to date. We include the complications that occur because of mechanisms that occur at the level of a few, or one, quantum excitation. Two factors combine in the work to date that limit the value of the approach. These are: (1) the weak signal tends to require operation of the amplifier in the linear regime where the important advantages of nonlinear optical processing are not accessed, (2) the linear optical amplifier has a -3dB noise figure (SN(out)/SN(in)) that necessarily degrades the signal. Some improvement is gained because the gain provided by the optical amplifier can be used to overcome losses in the heterodyned process and photodetection. The result, however, is that introduction of an optical amplifier in a well optimized coherent lidar system results in, at best, a modest improvement in signal to noise. Some improvement may also be realized on incorporating more optical components in a coherent lidar system for purely practical reasons. For example, more compact, lighter weight, components, more robust alignment, or more rapid processing may be gained. We further find that there remain a number of potentially valuable, but unexplored options offered both by the rapidly expanding base of optical technology and the recent investigation of novel nonlinear coherent interference phenomena occurring at the single quantum excitation level. Key findings are: (1) insertion of linear optical

  3. Generation of high beam quality, high-energy and broadband tunable mid-infrared pulse from a KTA optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Chen, Yun; Li, Yanyan; Li, Wenkai; Guo, Xiaoyang; Leng, Yuxin

    2016-04-01

    We have demonstrated efficient generation of high beam quality, high-energy and broadband tunable femtosecond mid-infrared pulses using a three-stage collinear optical parametric amplifier (OPA). The white-light continuum (WLC) seeded OPA setup, based on KTA crystal in three stages and pumped by a femtosecond laser pulse at 800 nm, is capable of producing idler wavelength ranging from 2.4 μm to 4.0 μm with energy up to 82 μJ at 3.27 μm, which corresponds to signal energy of 350 μJ at 1060 nm. The output pulse has excellent intensity distribution with measured beam quality factor M2~1.1 for signal and M2~1.7 for idler. To our knowledge, this is the best beam quality reported in 3-5 μm femtosecond OPA until now. The achieved mid-infrared pulse also has a good energy stability with a fluctuation of 1.01% rms over half an hour.

  4. High-energy noncollinear optical parametric amplifier producing 4  fs pulses in the visible seeded by a gas-phase filament.

    PubMed

    Odhner, Johanan H; Levis, Robert J

    2015-08-15

    We report on the design and characterization of a short-pulse-pumped, single-stage noncollinear optical parametric amplifier (NOPA) that achieves high pulse energies in the few-cycle pulse regime. Optimal pulse-front tilting and temporal compression of the short (35 fs) pump pulse are achieved using a 4f grating compressor, while spatial chirp at the NOPA crystal is eliminated with proper imaging using a pair of reflective telescopes. Gas-phase filamentation in an open-ended argon-filled cell provides a bright, stable seed source with little residual chirp that is suitable for temporal overlap with the short pump pulse without dispersion precompensation. Two seeding geometries are explored, and pulses as short as 3.5 fs are obtained by seeding with the entire filament bandwidth. Fourier-transform-limited 4 fs pulses are obtained by filtering the IR portion of the spectrum.

  5. Calculations of superconducting parametric amplifiers performances

    NASA Astrophysics Data System (ADS)

    Goto, T.; Takeda, M.; Saito, S.; Shimakage, H.

    2017-07-01

    A superconducting parametric amplifier is an electromagnetic wave amplifier with high-quality characteristics such as a wide bandwidth, an extremely low noise, and a high dynamic range. In this paper, we report on the estimations of a YBCO superconducting parametric amplifier characteristic. The YBCO thin films were deposited on an MgO substrate by a pulsed laser deposition method. Based on the measured YBCO thin film parameters, theoretical calculations were implemented for evaluations of kinetic inductance nonlinearities and parametric gains. The nonlinearity of the YBCO thin film was estimated to be stronger than a single crystal NbTiN thin film. It is indicated that the YBCO parametric amplifier has a potential to be realized the amplifier with the high parametric gain. It is also expected that it could be operated in the range of the high frequency band, at the high temperature, and low applied current.

  6. Nondegenerate optical parametric chirped pulse amplifier

    DOEpatents

    Jovanovic, Igor; Ebbers, Christopher A.

    2005-03-22

    A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.

  7. Ultra-broadband amplification properties of Ni2+-doped glass-ceramics amplifiers.

    PubMed

    Jiang, Chun

    2009-04-13

    The energy level, transition configuration and mathematical model of Ni(2+)-doped glass-ceramics amplifiers are presented for the first time, to the best of one's knowledge. A quasi-three-level system is employed to model the gain and noise characteristics of the doped system, and the rate and power propagation equations of the mathematical model are solved to analyze the effect of the active ion concentration, fiber length, pump power as well as thermal-quenching on the gain spectra. It is shown that our model is in agreement with experimental result, and when excited at longer wavelength, the center of gain spectra of the amplifier red shifts, the ultra-broad band room-temperature gain spectra can cover 1.25-1.65 microm range for amplification of signal in the low-loss windows of the all-wave fiber without absorption peak caused by OH group.

  8. Improved energy coupling into the gain region of the Ni-like Pd transient collisional x-ray laser

    SciTech Connect

    Smith, R; Dunn, J; Filevich, J; Moon, S; Nilsen, J; Keenan, R; Shlyaptsev, V; Rocca, J; Hunter, J; Shepherd, R; Booth, R; Marconi, M

    2004-10-05

    We present within this paper a series of experiments, which yield new observations to further our understanding of the transient collisional x-ray laser medium. We use the recently developed technique of picosecond x-ray laser interferometry to probe the plasma conditions in which the x-ray laser is generated and propagates. This yields two dimensional electron density maps of the plasma taken at different times relative to the peak of the 600ps plasma-forming beam. In another experimental campaign, the output of the x-ray laser plasma column is imaged with a spherical multilayer mirror onto a CCD camera to give a two-dimensional intensity map of the x-ray laser output. Near-field imaging gives insights into refraction, output intensity and spatial mode structure. Combining these images with the density maps gives an indication of the electron density at which the x-ray laser is being emitted at (yielding insights into the effect of density gradients on beam propagation). Experimental observations coupled with simulations predict that most effective coupling of laser pump energy occurs when the duration of the main heating pulse is comparable to the gain lifetime ({approx}10ps for Ni-like schemes). This can increase the output intensity by more than an order of magnitude relative to the case were the same pumping energy is delivered within a shorter heating pulse duration (< 3ps). We have also conducted an experiment in which the output of the x-ray laser was imaged onto the entrance slit of a high temporal resolution streak camera. This effectively takes a one-dimensional slice of the x-ray laser spatial profile and sweeps it in time. Under some conditions we observe rapid movement of the x-ray laser ({approx} 3 {micro}m/ps) towards the target surface.

  9. A high-fat, ketogenic diet causes hepatic insulin resistance in mice, despite increasing energy expenditure and preventing weight gain.

    PubMed

    Jornayvaz, François R; Jurczak, Michael J; Lee, Hui-Young; Birkenfeld, Andreas L; Frederick, David W; Zhang, Dongyang; Zhang, Xian-Man; Samuel, Varman T; Shulman, Gerald I

    2010-11-01

    Low-carbohydrate, high-fat ketogenic diets (KD) have been suggested to be more effective in promoting weight loss than conventional caloric restriction, whereas their effect on hepatic glucose and lipid metabolism and the mechanisms by which they may promote weight loss remain controversial. The aim of this study was to explore the role of KD on liver and muscle insulin sensitivity, hepatic lipid metabolism, energy expenditure, and food intake. Using hyperinsulinemic-euglycemic clamps, we studied insulin action in mice fed a KD or regular chow (RC). Body composition was assessed by ¹H magnetic resonance spectroscopy. Despite being 15% lighter (P < 0.001) than RC-fed mice because of a 17% increase in energy expenditure (P < 0.001), KD-fed mice manifested severe hepatic insulin resistance, as reflected by decreased suppression (0% vs. 100% in RC-fed mice, P < 0.01) of endogenous glucose production during the clamp. Hepatic insulin resistance could be attributed to a 350% increase in hepatic diacylglycerol content (P < 0.001), resulting in increased activation of PKCε (P < 0.05) and decreased insulin receptor substrate-2 tyrosine phosphorylation (P < 0.01). Food intake was 56% (P < 0.001) lower in KD-fed mice, despite similar caloric intake, and could partly be attributed to a more than threefold increase (P < 0.05) in plasma N-acylphosphatidylethanolamine concentrations. In conclusion, despite preventing weight gain in mice, KD induces hepatic insulin resistance secondary to increased hepatic diacylglycerol content. Given the key role of nonalcoholic fatty liver disease in the development of type 2 diabetes and the widespread use of KD for the treatment of obesity, these results may have potentially important clinical implications.

  10. Gain drift compensation with no-feedback-loop developed for the X-IFU/ATHENA readout chain

    NASA Astrophysics Data System (ADS)

    Prêle, D.; Voisin, F.; Beillimaz, C.; Chen, S.; Goldwurm, A.

    2016-07-01

    The focal plane of the X-ray Integral Field Unit (X-IFU) instrument of the Athena observatory is composed of about 4000 micro-calorimeters. These sensors, based on superconducting Transition Edge Sensors, are read out through a frequency multiplexer and a base-band feedback to linearize SQUIDs. However, the loop gain of this feedback is lower than 10 in the modulated TES signal bandwidth, which is not enough to fix the gain of the full readout chain. Calibration of the instrument is planned to be done at a time scale larger than a dozen minutes and the challenging energy resolution goal of 2.5 eV at 6 keV will probably require a gain stability larger than 10-4 over a long duration. A large part of this gain is provided by a Low-Noise Amplifier (LNA) in the Warm Front-End Electronics (WFEE). To reach such gain stability over more than a dozen minutes, this non-cooled amplifier has to cope with the temperature and supply voltage variations. Moreover, mainly for noise reasons, common large loop gain with feedback can not be used. We propose a new amplifier topology using diodes as loads of a differential amplifier to provide a fixed voltage gain, independent of the temperature and of the bias fluctuations. This amplifier is designed using a 350 nm SiGe BiCMOS technology and is part of an integrated circuit developed for the WFEE. Our simulations provide the expected gain drift and noise performances of such structure. Comparison with standard resistive loaded differential pair clearly shows the advantages of the proposed amplifier topology with a gain drift decreasing by more than an order of magnitude. Performances of this diode loaded amplifier are discussed in the context of the X-IFU requirements.

  11. DIAMOND AMPLIFIED PHOTOCATHODES.

    SciTech Connect

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

    2007-11-26

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

  12. The microstrip SQUID amplifier

    NASA Astrophysics Data System (ADS)

    Therrien, Roy

    A Superconducting Quantum Interference Devices (SQUIDS) can operate at frequencies up to several GHz and can be cooled to less than 100 mK. Such characteristics make the SQUID---a flux-to-voltage transducer---an excellent candidate for use as a low-noise rf amplifier. Coupling of input signals of frequencies larger than 200 MHz, however, has been limited by the parasitic capacitance between the input coil and SQUID body. We present experimental observations of a do SQUID-based rf amplifier which circumvents this problem by incorporating the input coil as a microstrip resonator. The microstrip input configuration uses the capacitance and inductance of the input coil to form a resonant cavity capable of operating up to several GHz. The input signal is applied between the SQUID body and one end of the input coil, while the other end of the coil is left open. We present data from microstrip SQUID amplifiers with gains of up to 22 dB at 900 MHz. In order to understand the gain and input impedance of the microstrip SQUID in greater detail, we made and studied a 1:190 scale analog patterned on a double-sided printed circuit board consisting of copper deposited on a kapton sheet. The measured input impedance of the analog SQUID is successfully modeled by describing the microstrip input as a low-loss transmission line. When operated with the slit in the copper washer ground plane shorted, the input coil behaves exactly like a linear resonator with the resonant frequency given by f = 1/2ℓ(L 0C0)1/2, where L0 and C0 are the inductance and capacitance per unit length and ℓ is the coil length. With the slit in the washer left open, the inductance of the input coil is significantly altered in a manner partially consistent with the Ketchen-Jaycox model in which the reflected inductance of the input coil is Li = n2L, where L is the inductance of the washer loop and n is the number of turns in the coil. We present input impedance measurements on microstrip SQUIDs cooled to 4

  13. Digital system provides superregulation of nanosecond amplifier-discriminator circuit

    NASA Technical Reports Server (NTRS)

    Forges, K. G.

    1966-01-01

    Feedback system employing a digital logic comparator to detect and correct amplifier drift provides stable gain characteristics for nanosecond amplifiers used in counting applications. Additional anticoincidence logic enables application of the regulation circuit to the amplifier and discriminator while they are mounted in an operable circuit.

  14. Analysis of FEL-based CeC amplification at high gain limit

    SciTech Connect

    Wang, G.; Litvinenko, V.; Jing, Y.

    2015-05-03

    An analysis of Coherent electron Cooling (CeC) amplifier based on 1D Free Electron Laser (FEL) theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution. At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter. In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution and investigate how longitudinal space charge and electrons’ energy spread affect the FEL amplification process.

  15. Multi-pass light amplifier

    NASA Technical Reports Server (NTRS)

    Plaessmann, Henry (Inventor); Grossman, William M. (Inventor)

    1997-01-01

    A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. The optical gain medium may be solid-state, liquid or gaseous medium and may be pumped longitudinally or transversely. In a second embodiment, first and second mirrors face a third mirror in a White Cell configuration, and the optical gain medium is positioned at or adjacent to one of the mirrors. Defocusing means and optical gain medium cooling means are optionally provided with either embodiment, to controllably defocus the light beam, to cool the optical gain medium and to suppress thermal lensing in the gain medium.

  16. Injection seeded, diode pumped regenerative ring Nd:YAG amplifier for spaceborne laser ranging technology development

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

    1992-01-01

    A small, all solid state, regenerative ring amplifier designed as a prototype for space application is discussed. Novel features include dual side pumping of the Nd:YAG crystal and a triangular ring cavity design which minimizes the number of optical components and losses. The amplifier is relatively small (3 ns round trip time) even though standard optical elements are employed. The ring regeneratively amplifies a 100 ps single pulse by approximately 10(exp 5) at a repetition rate of 10 to 100 Hz. The amplifier is designed to be injection seeded with a pulsed, 100 ps laser diode at 1.06 microns, but another Nd:YAG laser system supplying higher pulse energies was employed for laboratory experiment. This system is a prototype laser oscillator for the Geoscience Laser Ranging System (GLRS) platform. Results on measurements of beam quality, astigmatism, and gain are given.

  17. A Low Cost Bluetooth Low Energy Transceiver for Wireless Sensor Network Applications with a Front-end Receiver-Matching Network-Reusing Power Amplifier Load Inductor.

    PubMed

    Liang, Zhen; Li, Bin; Huang, Mo; Zheng, Yanqi; Ye, Hui; Xu, Ken; Deng, Fangming

    2017-04-19

    In this work, a low cost Bluetooth Low Energy (BLE) transceiver for wireless sensor network (WSN) applications, with a receiver (RX)-matching network-reusing power amplifier (PA) load inductor, is presented. In order to decrease the die area, only two inductors were used in this work. Besides the one used in the voltage control oscillator (VCO), the PA load inductor was reused as the RX impedance matching component in the front-end. Proper controls have been applied to achieve high transmitter (TX) input impedance when the transceiver is in the receiving mode, and vice versa. This allows the TRX-switch/matching network integration without significant performance degradation. The RX adopted a low-IF structure and integrated a single-ended low noise amplifier (LNA), a current bleeding mixer, a 4th complex filter and a delta-sigma continuous time (CT) analog-to-digital converter (ADC). The TX employed a two-point PLL-based architecture with a non-linear PA. The RX achieved a sensitivity of -93 dBm and consumes 9.7 mW, while the TX achieved a 2.97% error vector magnitude (EVM) with 9.4 mW at 0 dBm output power. This design was fabricated in a 0.11 μm complementary metal oxide semiconductor (CMOS) technology and the front-end circuit only occupies 0.24 mm². The measurement results verify the effectiveness and applicability of the proposed BLE transceiver for WSN applications.

  18. Estrogen response element-independent signaling partially restores post-ovariectomy body weight gain but is not sufficient for 17β-estradiol's control of energy homeostasis.

    PubMed

    Mamounis, Kyle J; Yang, Jennifer A; Yasrebi, Ali; Roepke, Troy A

    2014-03-01

    The steroid 17β-estradiol (E2) modulates energy homeostasis by reducing feeding behavior and increasing energy expenditure primarily through estrogen receptor α (ERα)-mediated mechanisms. Intact ERαKO female mice develop obesity as adults exhibiting decreased energy expenditure and increased fat deposition. However, intact transgenic female mice expressing a DNA-binding-deficient ERα (KIKO) are not obese and have similar energy expenditure, activity and fat deposition as to wild type (WT) females, suggesting that non-estrogen response element (ERE)-mediated signaling is important in E2 regulation of energy homeostasis. Initial reports did not examine the effects of ovariectomy on energy homeostasis or E2's attenuation of post-ovariectomy body weight gain. Therefore, we sought to determine if low physiological doses of E2 (250 ng QOD) known to suppress post-ovariectomy body weight gain in WT females would suppress body weight gain in ovariectomized KIKO females. We observed that the post-ovariectomy increase in body weight was significantly greater in WT females than in KIKO females. Furthermore, E2 did not significantly attenuate the body weight gain in KIKO females as it did in WT females. E2 replacement suppressed food intake and fat accumulation while increasing nighttime oxygen consumption and activity only in WT females. E2 replacement also increased arcuate POMC gene expression in WT females only. These data suggest that in the intact female, ERE-independent mechanisms are sufficient to maintain normal energy homeostasis and to partially restore the normal response to ovariectomy. However, they are not sufficient for E2's suppression of post-ovariectomy body weight gain and its effects on metabolism and activity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Estrogen response element-independent signaling partially restores post-ovariectomy body weight gain but is not sufficient for 17β-estradiol’s control of energy homeostasis

    PubMed Central

    Mamounis, Kyle J.; Yang, Jennifer A.; Yasrebi, Ali; Roepke, Troy A.

    2013-01-01

    The steroid 17β-estradiol (E2) modulates energy homeostasis by reducing feeding behavior and increasing energy expenditure primarily through estrogen receptor α (ERα)-mediated mechanisms. Intact ERαKO female mice develop obesity as adults exhibiting decreased energy expenditure and increased fat deposition. However, intact transgenic female mice expressing a DNA-binding-deficient ERα (KIKO) are not obese and have similar energy expenditure, activity and fat deposition to wild type (WT) females, suggesting that non-Estrogen Response Element (ERE)-mediated signaling is important in E2 regulation of energy homeostasis. However, initial reports did not examine the effects of ovariectomy on energy homeostasis or E2’s attenuation of post-ovariectomy body weight gain. Therefore, we sought to determine if low physiological doses of E2 (250 ng QOD) known to suppress post-ovariectomy body weight gain in WT females, would suppress body weight gain in ovariectomized KIKO females. We observed that the post-ovariectomy increase in body weight was significantly greater in WT females than in KIKO females. Furthermore, E2 did not significantly attenuate the body weight gain in KIKO females as it did in WT females. E2 replacement suppressed food intake and fat accumulation while increasing nighttime oxygen consumption and activity only in WT females. E2 replacement also increased arcuate POMC gene expression in WT females only. These data suggest that in the intact female, ERE-independent mechanisms are sufficient to maintain normal energy homeostasis and to partially restore the normal response to ovariectomy. However, they are not sufficient for E2’s suppression of post-ovariectomy body weight gain and attenuation of decreases in metabolism and activity. PMID:24252383

  20. The physics of transverse mode instability-induced nonlinear phase distortions in large area optical fiber amplifiers and their mitigation with applications in scaling of pulsed and continuous wave high-energy lasers

    DTIC Science & Technology

    2016-12-13

    their mitigation with applications in scaling of pulsed and continuous- wave high- energy lasers Balaji Srinivasan INDIAN INSTITUTE OF TECHNOLOGY...high- energy lasers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-5044 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Balaji Srinivasan 5d...use of vortex beams to mitigate thermal mode instability in high energy fiber amplifiers. The investigation is carried out through (1) the

  1. Plasma conditions for improved energy coupling into the gain region of the Ni-like Pd transient collisional x-ray laser

    SciTech Connect

    Smith, R F; Dunn, J; Filevich, J; Moon, S; Nilsen, J; Keenan, R; Shlyaptsev, V N; Rocca, J J; Hunter, J R; Marconi, M C

    2004-10-04

    We have directly probed the plasma conditions in which the Ni-like Pd transient collisional x-ray laser is generated and propagates by measuring the near-field image and by utilizing picosecond resolution soft x-ray laser interferometry of the preformed Pd plasma gain medium. The electron density and gain region of the plasma have been determined experimentally and are found to be in good agreement with simulations. We observe a strong dependence of the laser pump-gain medium coupling on the laser pump parameters. The most efficient coupling of laser pump energy into the gain region occurs with the formation of lower density gradients in the pre-formed plasma and when the duration of the main heating pulse is comparable to the gain lifetime ({approx}10ps for mid-Z Ni-like schemes). This increases the output intensity by more than an order of magnitude relative to the commonly utilized case where the same pumping energy is delivered within a shorter heating pulse duration (< 3ps). In contrast, the higher intensity heating pulses are observed to be absorbed at higher electron densities and in regions where steep density gradients limit the effective length of the gain medium.

  2. [Influence of maternal nutritional status, weight gain and energy intake on fetal growth in high-risk pregnancies].

    PubMed

    Nomura, Roseli Mieko Yamamoto; Paiva, Letícia Vieira; Costa, Verbênia Nunes; Liao, Adolfo Wenjaw; Zugaib, Marcelo

    2012-03-01

    To analyze the influence of maternal nutritional status, weight gain and energy consumption on fetal growth in high-risk pregnancies. A prospective study from August 2009 to August 2010 with the following inclusion criteria: puerperae up to the 5th postpartum day; high-risk singleton pregnancies (characterized by medical or obstetrical complications during pregnancy); live fetus at labor onset; delivery at the institution; maternal weight measured on the day of delivery, and presence of medical and/or obstetrical complications characterizing pregnancy as high-risk. Nutritional status was assessed by pregestational body mass index and body mass index in late pregnancy, and the patients were classified as: underweight, adequate, overweight and obese. A food frequency questionnaire was applied to evaluate energy consumption. We investigated maternal weight gain, delivery data and perinatal outcomes, as well as fetal growth based on the occurrence of small for gestational age and large for gestational age neonates. We included 374 women who were divided into three study groups according to newborn birth weight: adequate for gestational age (270 cases, 72.2%), small for gestational age (91 cases, 24.3%), and large for gestational age (13 cases, 3.5%). Univaried analysis showed that women with small for gestational age neonates had a significantly lower mean pregestational body mass index (23.5 kg/m², p<0.001), mean index during late pregnancy (27.7 kg/m², p<0.001), and a higher proportion of maternal underweight at the end of pregnancy (25.3%, p<0.001). Women with large for gestational age neonates had a significantly higher mean pregestational body mass index (29.1 kg/m², p<0.001), mean index during late pregnancy (34.3 kg/m², p<0.001), and a higher proportion of overweight (30.8%, p=0.02) and obesity (38.5%, p=0.02) according to pregestational body mass index, and obesity at the end of pregnancy (53.8%, p<0.001). Multivariate analysis revealed the index value

  3. Temperature dependent spectroscopic characterization of Tm:YAG crystals as potential laser medium for pulsed high energy laser amplifiers

    NASA Astrophysics Data System (ADS)

    Körner, Jörg; Reiter, Jürgen; Lühder, Tilman; Hein, Joachim; Jambunathan, V.; Lucianetti, Antonio; Mocek, Tomáš; Kaluza, Malte C.

    2017-05-01

    Similar to ytterbium doped laser materials laser operation with thulium doped media is possible within a quasi-three level scheme, which especially for pulse pumped lasers is a drawback for efficient laser operation, as a significant amount of energy is required to bleach out the laser medium. Since this energy cannot be extracted, it is lost for the amplification process. Hence, operation of such lasers at cryogenic temperatures seems to be an appropriate solution. For further modeling and derivation of design rules for future laser systems based on such a scheme reliable spectral data is needed. We will present absorption and emission measurements on Tm:YAG as a function of temperature in the range from 80 K to 300 K covering both the absorption bands around 800 nm and the emission bands up to 2.1 μm. The spectral measurements were carried out on two samples of Tm:YAG with doping levels of 2 at.% and 8 at.%. Precautions for reabsorption effects were taken to allow for accurate results over the whole measurement range. From these measurements we have derived absorption and emission cross sections and radiative lifetimes. By comparing the latter values to values obtained by highly accurate measurements of the lifetime using the pinhole method we could also estimate the quantum efficiency.

  4. Visible-infrared self-amplified spontaneous emission amplifier free electron laser undulator

    NASA Astrophysics Data System (ADS)

    Carr, Roger; Cornacchia, Max; Emma, Paul; Nuhn, Heinz-Dieter; Poling, Ben; Ruland, Robert; Johnson, Erik; Rakowsky, George; Skaritka, John; Lidia, Steve; Duffy, Pat; Libkind, Marcus; Frigola, Pedro; Murokh, Alex; Pellegrini, Claudio; Rosenzweig, James; Tremaine, Aaron

    2001-12-01

    The visible-infrared self-amplified spontaneous emission amplifier (VISA) free electron laser (FEL) is an experimental device designed to show self-amplified spontaneous emission (SASE) to saturation in the near infrared to visible light energy range. It generates a resonant wavelength output from 800-600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is designed to show how SASE FEL theory corresponds with experiment in this wavelength range, using an electron beam with emittance close to that planned for the future Linear Coherent Light Source at SLAC. VISA comprises a 4 m pure permanent magnet undulator with four 99 cm segments, each of 55 periods, 18 mm long. The undulator has distributed focusing built into it, to reduce the average beta function of the 70-85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walk-off, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, we were able to control trajectory walk-off to less than +/-50 μm per field gain length.

  5. SQUARE WAVE AMPLIFIER

    DOEpatents

    Leavitt, M.A.; Lutz, I.C.

    1958-08-01

    An amplifier circuit is described for amplifying sigmals having an alternating current component superimposed upon a direct current component, without loss of any segnnent of the alternating current component. The general circuit arrangement includes a vibrator, two square wave amplifiers, and recombination means. The amplifier input is connected to the vibrating element of the vibrator and is thereby alternately applied to the input of each square wave amplifier. The detailed circuitry of the recombination means constitutes the novelty of the annplifier and consists of a separate, dual triode amplifier coupled to the output of each square wave amplifier with a recombination connection from the plate of one amplifier section to a grid of one section of the other amplifier. The recombination circuit has provisions for correcting distortion caused by overlapping of the two square wave voltages from the square wave amplifiers.

  6. Laser system using regenerative amplifier

    DOEpatents

    Emmett, John L. [Pleasanton, CA

    1980-03-04

    High energy laser system using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output.

  7. Laser system using regenerative amplifier

    DOEpatents

    Emmett, J.L.

    1980-03-04

    High energy laser system is disclosed using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output. 10 figs.

  8. Carrier dynamics in inhomogeneously broadened InAs/AlGaInAs/InP quantum-dot semiconductor optical amplifiers

    SciTech Connect

    Karni, O. Mikhelashvili, V.; Eisenstein, G.; Kuchar, K. J.; Capua, A.; Sęk, G.; Misiewicz, J.; Ivanov, V.; Reithmaier, J. P.

    2014-03-24

    We report on a characterization of fundamental gain dynamics in recently developed InAs/InP quantum-dot semiconductor optical amplifiers. Multi-wavelength pump-probe measurements were used to determine gain recovery rates, following a powerful optical pump pulse, at various wavelengths for different bias levels and pump excitation powers. The recovery was dominated by coupling between the electronic states in the quantum-dots and the high energy carrier reservoir via capture and escape mechanisms. These processes determine also the wavelength dependencies of gain saturation depth and the asymptotic gain recovery level. Unlike quantum-dash amplifiers, these quantum-dots exhibit no instantaneous gain response, confirming their quasi zero-dimensional nature.

  9. Modeling and optimization of tapered-diode pumped Cr:LiCAF regenerative amplifiers

    NASA Astrophysics Data System (ADS)

    Demirbas, Umit

    2013-01-01

    We present a numerical study, which investigates the potential of diode pumped Cr:LiCAF regenerative amplifiers in detail. Special attention has been given to relevant material properties of the gain media, like the Auger energy transfer upconversion (ETU) process, to utilize the full potential of the material and to develop guidelines in choosing optimal material properties like chromium doping concentration and length. Moreover, importance of pulsed pumping, rather than continuous-wave (cw) pumping, in obtaining higher small signal gain values is discussed in detail. Effects of pump power, cavity losses, excited-state absorption, seed pulse energy, optical damage and ETU on obtainable pulse energies will also be presented. The modeling results have shown that, Cr:LiCAF regenerative amplifiers pumped by two 675 nm state-of-the-art 1-W tapered diodes have the potential to produce 50-fs long pulses around 800 nm with 70 μJ pulse energy and 1.4 GW peak power at repetition rates up to 5 kHz. Moreover, a 20-W diode pumped Cr:LiCAF amplifier has the potential to produce pulse energies of 1.1 mJ and peak powers of 20 GW. Expected optical-to-optical conversion efficiencies of the systems are about 30%. These results demonstrate that, with ongoing progress in laser diode technology, low-cost and efficient Cr:Colquiriite amplifiers has the potential to replace the expensive Ti:Sapphire technology in the future.

  10. Cross-talk free, low-noise optical amplifier

    DOEpatents

    Dijaili, Sol P.; Patterson, Frank G.; Deri, Robert J.

    1995-01-01

    A low-noise optical amplifier solves crosstalk problems in optical amplifiers by using an optical cavity oriented off-axis (e.g. perpendicular) to the direction of a signal amplified by the gain medium of the optical amplifier. Several devices are used to suppress parasitic lasing of these types of structures. The parasitic lasing causes the gain of these structures to be practically unusable. The lasing cavity is operated above threshold and the gain of the laser is clamped to overcome the losses of the cavity. Any increase in pumping causes the lasing power to increase. The clamping action of the gain greatly reduces crosstalk due to gain saturation for the amplified signal beam. It also reduces other nonlinearities associated with the gain medium such as four-wave mixing induced crosstalk. This clamping action can occur for a bandwidth defined by the speed of the laser cavity. The lasing field also reduces the response time of the gain medium. By having the lasing field off-axis, no special coatings are needed. Other advantages are that the lasing field is easily separated from the amplified signal and the carrier grating fluctuations induced by four-wave mixing are decreased. Two related methods reduce the amplified spontaneous emission power without sacrificing the gain of the optical amplifier.

  11. Cross-talk free, low-noise optical amplifier

    DOEpatents

    Dijaili, S.P.; Patterson, F.G.; Deri, R.J.

    1995-07-25

    A low-noise optical amplifier solves crosstalk problems in optical amplifiers by using an optical cavity oriented off-axis (e.g. perpendicular) to the direction of a signal amplified by the gain medium of the optical amplifier. Several devices are used to suppress parasitic lasing of these types of structures. The parasitic lasing causes the gain of these structures to be practically unusable. The lasing cavity is operated above threshold and the gain of the laser is clamped to overcome the losses of the cavity. Any increase in pumping causes the lasing power to increase. The clamping action of the gain greatly reduces crosstalk due to gain saturation for the amplified signal beam. It also reduces other nonlinearities associated with the gain medium such as four-wave mixing induced crosstalk. This clamping action can occur for a bandwidth defined by the speed of the laser cavity. The lasing field also reduces the response time of the gain medium. By having the lasing field off-axis, no special coatings are needed. Other advantages are that the lasing field is easily separated from the amplified signal and the carrier grating fluctuations induced by four-wave mixing are decreased. Two related methods reduce the amplified spontaneous emission power without sacrificing the gain of the optical amplifier. 11 figs.

  12. Compressed magnetic flux amplifier with capacitive load

    SciTech Connect

    Stuetzer, O.M.

    1980-03-01

    A first-order analysis is presented for a compressed magnetic flux (CMF) current amplifier working into a load with a capacitive component. Since the purpose of the investigation was to gain a general understanding of the arrangement, a number of approximations and limitations were accepted. The inductance of the transducer varies with time; the inductance/resistance/capacitance (LRC) circuit therefore is parametric and solutions are different for the stable regime (high C), the oscillation regime (low C), and the transition case. Solutions and performance depend strongly on circuit boundary conditions, i.e., energization of the circuit by either an injected current or by an applied capacitor charge. The behavior of current and energy amplification for the various cases are discussed in detail. A number of experiments with small CMF devices showed that the first-order theory presented predicts transducer performance well in the linear regime.

  13. Effects of L-carnitine supplementation on milk production, litter gains and back-fat thickness in sows with a low energy and protein intake during lactation.

    PubMed

    Ramanau, A; Kluge, H; Eder, K

    2005-05-01

    The present study investigated the effect of L-carnitine supplementation during pregnancy (125 mg/d) and lactation (250 mg/d) on milk production, litter gains and back-fat thickness in sows fed a low-energy and low-protein diet during lactation. Sows supplemented with L-carnitine produced more milk on days 11 and 18 of lactation (+18 %; P<0.05) and had higher litter gains during suckling (+20 %; P<0.01) than control sows. Loss of body weight during lactation was similar in both groups, but sows supplemented with L-carnitine had a greater reduction of back-fat thickness (+45 %; P<0.05) during lactation than control sows. In conclusion, this study shows that L-carnitine increases milk production and litter gains in sows in a strongly negative energy and N balance, and enhances body fat mobilisation.

  14. Neodymium-complex-doped photodefined polymer channel waveguide amplifiers.

    PubMed

    Yang, Jing; Diemeer, Mart B J; Geskus, Dimitri; Sengo, Gabriël; Pollnau, Markus; Driessen, Alfred

    2009-02-15

    Channel waveguides based on a polymer, 6-fluorinated-dianhydride/epoxy, which is actively doped with a Nd complex, Nd(thenoyltrifluoroacetone)(3) 1,10-phenanthroline, are fabricated by a simple and reproducible procedure, spin coating a photodefinable cladding polymer onto a thermally oxidized silicon wafer, photopatterning, backfilling with the active core polymer, and spin coating with an upper cladding layer. Photoluminescence at 1060 nm from the Nd(3+) ions with a lifetime of 130 mus is observed. Optical gain at 1060 nm is demonstrated in channel waveguides with different Nd(3+) concentrations. By accounting for the waveguide loss of 0.1 dB/cm, an internal net gain of 8 dB is demonstrated for a 5.6-cm-long channel waveguide amplifier. Owing to the nature of the Nd(3+) complex, energy-transfer upconversion affects the gain only at Nd(3+) concentrations above 1 x 10(20) cm(-3).

  15. Testing of active Fresnel rhomb zig-zag slab amplifier

    SciTech Connect

    Bikmatov, R.G.; Charikov, A.V.; Chernyak, V.M.; Ignat`ev, L.P.; Kondrashov, V.N.; Kuznetsov, V.G.; Nikolaevskii, V.G.; Nugumanov, A.M.; Pergament, M.I.; Rozhkov, A.D.; Manes, K.

    1995-12-31

    The work is devoted to the investigation of a wide-aperture amplifier which is intended to be installed in the laser system Nova Upgrade. The amplifier should meet rather severe requirements. The authors have carried out the experimental investigation of gain nonuniformity over all the aperture of the amplifier and estimated depolarization and phase distortions to determine the sizes of the amplifier aperture operating zone.

  16. Cladding-pumped erbium-doped multicore fiber amplifier.

    PubMed

    Abedin, K S; Taunay, T F; Fishteyn, M; DiGiovanni, D J; Supradeepa, V R; Fini, J M; Yan, M F; Zhu, B; Monberg, E M; Dimarcello, F V

    2012-08-27

    A cladding pumped multicore erbium-doped fiber amplifier for simultaneous amplification of 6 channels is demonstrated. Peak gain over 32 dB has been obtained at a wavelength of 1560 nm and the bandwidth measured at 20-dB gain was about 35 nm. Numerical modeling of cladding pumped multicore erbium-doped amplifier was also performed to study the properties of the amplifier. The results of experiment and simulation are found to be in good agreement.

  17. Some characteristic features of the construction of the amplifying channel for working with semiconductor detectors in the charged particle energy spectrometer. [noise minimization at preamplifier input

    NASA Technical Reports Server (NTRS)

    Kuzyuta, E. I.

    1974-01-01

    A transistorized spectrometric amplifier with a shaper is reported that selects the shape of the frequency characteristic of the amplifying channel for which the primary frequency spectrum of the signal will pass, but where the noise spectrum is limited to the maximum. A procedure is presented for selecting the shaping circuits and their inclusion principles.

  18. Monolithic semiconductor light emitter and amplifier

    NASA Technical Reports Server (NTRS)

    Carlson, Nils W. (Inventor)

    1992-01-01

    A semiconductor light emitter comprising a substrate of a semiconductor material having a pair of opposed surfaces and a body of semiconductor material on one of the surfaces. The body includes a pair of clad layers of opposite conductivity types having an intermediate quantum well region therebetween. The clad layers are of a semiconductor material which forms a heterojunction with the material of the quantum well region. The clad layers and the quantum well region form a waveguide which extends along the body. A plurality of gain sections are formed in the body spaced along and optically coupled by the waveguide. Each of the gain sections is adapted to generate light therein when a voltage is placed thereacross. One of the gain section has gratings at each end thereof which are adapted to reflect light back into the one gain section and thereby create a beam of light. The grating between the one gain section and an adjacent gain section is adapted to allow some of the light generated in the one gain section to pass therethrough along the waveguide to the next gain section. Each of the other gain sections have gratings adjacent an end opposite the first gain sections. The periods of the grating are such that no self-oscillation of the light in the waveguide occurs so that each of the other gain sections serve as single pass amplifiers. The gratings also direct the amplified light from the other gain sections out of the body.

  19. Hybrid matrix amplifier

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.

    1995-01-01

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

  20. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2010-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.