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Sample records for average power femtosecond

  1. 100 W average power femtosecond laser at 343 nm.

    PubMed

    Rothhardt, Jan; Rothhardt, Carolin; Müller, Michael; Klenke, Arno; Kienel, Marco; Demmler, Stefan; Elsmann, Tino; Rothhardt, Manfred; Limpert, Jens; Tünnermann, Andreas

    2016-04-15

    We present a femtosecond laser system delivering up to 100 W of average power at 343 nm. The laser system employs a Yb-based femtosecond fiber laser and subsequent second- and third-harmonic generation in beta barium borate (BBO) crystals. Thermal gradients within these BBO crystals are mitigated by sapphire heat spreaders directly bonded to the front and back surface of the crystals. Thus, a nearly diffraction-limited beam quality (M2 < 1.4) is achieved, despite the high thermal load to the nonlinear crystals. This laser source is expected to push many industrial and scientific applications in the future. PMID:27082370

  2. Industry-grade high average power femtosecond light source

    NASA Astrophysics Data System (ADS)

    Heckl, O. H.; Weiler, S.; Fleischhaker, R.; Gebs, R.; Budnicki, A.; Wolf, M.; Kleinbauer, J.; Russ, S.; Kumkar, M.; Sutter, D. H.

    2014-03-01

    Ultrashort pulses are capable of processing practically any material with negligible heat affected zone. Typical pulse durations for industrial applications are situated in the low picosecond-regime. Pulse durations of 5 ps or below are a well established compromise between the electron-phonon interaction time of most materials and the need for pulses long enough to suppress detrimental effects such as nonlinear interaction with the ablated plasma plume. However, sub-picosecond pulses can further increase the ablation efficiency for certain materials, depending on the available average power, pulse energy and peak fluence. Based on the well established TruMicro 5000 platform (first release in 2007, third generation in 2011) an Yb:YAG disk amplifier in combination with a broadband seed laser was used to scale the output power for industrial femtosecond-light sources: We report on a subpicosecond amplifier that delivers a maximum of 160 W of average output power at pulse durations of 750 fs. Optimizing the system for maximum peak power allowed for pulse energies of 850 μJ at pulse durations of 650 fs. Based on this study and the approved design of the TruMicro 5000 product-series, industrygrade, high average power femtosecond-light sources are now available for 24/7 operation. Since their release in May 2013 we were able to increase the average output power of the TruMicro 5000 FemtoEdition from 40 W to 80 W while maintaining pulse durations around 800 fs. First studies on metals reveal a drastic increase of processing speed for some micro processing applications.

  3. Metal deep engraving with high average power femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Faucon, M.; Mincuzzi, G.; Morin, F.; Hönninger, C.; Mottay, E.; Kling, R.

    2015-03-01

    Deep engraving of 3D textures is a very demanding process for the creation of master tool e. g molds, forming tools or coining dies. As these masters are uses for reproduction of 3D patterns the materials for the tools are typically hard and brittle and thus difficult to machine. The new generation of industrial femtosecond lasers provides both high accuracy engraving results and high ablation rates at the same time. Operation at pulse energies of typically 40 μJ and repetition rates in the Mhz range the detrimental effect of heat accumulation has to be avoided. Therefore high scanning speeds are required to reduce the pulse overlap below 90%. As a consequence scan speeds in the range of 25-50 m/s a needed, which is beyond the capability of galvo scanners. In this paper we present results using a combination of a polygon scanner with a high average power femtosecond laser and compare this to results with conventional scanners. The effects of pulse energy and scan speed of the head on geometrical accuracy are discussed. The quality of the obtained structures is analyzed by means of 3D surface metrology microscope as well as SEM images.

  4. ICAN as a new laser paradigm for high energy, high average power femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Brocklesby, W. S.; Nilsson, J.; Schreiber, T.; Limpert, J.; Brignon, A.; Bourderionnet, J.; Lombard, L.; Michau, V.; Hanna, M.; Zaouter, Y.; Tajima, T.; Mourou, Gérard

    2014-05-01

    The application of petawatt lasers to scientific and technological problems is advancing rapidly. The usefulness of these applications will depend on being able to produce petawatt pulses at much higher repetition rates than is presently possible. The International Coherent Amplification Network (ICAN) consortium seeks to design high repetition rate petawatt lasers using large scale coherent beam combination of femtosecond pulse amplifiers built from optical fibres. This combination of technologies has the potential to overcome many of the hurdles to high energy, high average power pulsed lasers, opening up applications and meeting societal challenges.

  5. 275 W average output power from a femtosecond thin disk oscillator operated in a vacuum environment.

    PubMed

    Saraceno, Clara J; Emaury, Florian; Heckl, Oliver H; Baer, Cyrill R E; Hoffmann, Martin; Schriber, Cinia; Golling, Matthias; Südmeyer, Thomas; Keller, Ursula

    2012-10-01

    We present an ultrafast thin disk laser that generates an average output power of 275 W, which is higher than any other modelocked laser oscillator. It is based on the gain material Yb:YAG and operates at a pulse duration of 583 fs and a repetition rate of 16.3 MHz resulting in a pulse energy of 16.9 μJ and a peak power of 25.6 MW. A SESAM designed for high damage threshold initiated and stabilized soliton modelocking. We reduced the nonlinearity of the atmosphere inside the cavity by several orders of magnitude by operating the oscillator in a vacuum environment. Thus soliton modelocking was achieved at moderate amounts of self-phase modulation and negative group delay dispersion. Our approach opens a new avenue for power scaling femtosecond oscillators to the kW level. PMID:23188316

  6. 16.2-W average power from a diode-pumped femtosecond Yb:YAG thin disk laser.

    PubMed

    Aus der Au, J; Spühler, G J; Südmeyer, T; Paschotta, R; Hövel, R; Moser, M; Erhard, S; Karszewski, M; Giesen, A; Keller, U

    2000-06-01

    We demonstrate a power-scalable concept for high-power all-solid-state femtosecond lasers, based on passive mode locking of Yb:YAG thin disk lasers with semiconductor saturable-absorber mirrors. We obtained 16.2 W of average output power in pulses with 730-fs duration, 0.47-muJ pulse energy, and 560-kW peak power. This is to our knowledge the highest average power reported for a laser oscillator in the subpicosecond regime. Single-pass frequency doubling through a 5-mm-long lithium triborate crystal (LBO) yields 8-W average output power of 515-nm radiation. PMID:18064208

  7. Microdrilling of metals using femtosecond laser pulses and high average powers at 515 nm and 1030 nm

    NASA Astrophysics Data System (ADS)

    Döring, S.; Ancona, A.; Hädrich, S.; Limpert, J.; Nolte, S.; Tünnermann, A.

    2010-07-01

    We investigate the microdrilling of metals (stainless steel, copper and tungsten) for two different wavelengths, 1030 nm and 515 nm, in the regime of femtosecond laser pulses. An ytterbium-doped fibre CPA system provides high pulse energies (up to 70 μJ) and high repetition rates (up to 800 kHz), corresponding to high average powers of about 50 W, for this experimental study.

  8. Femtosecond Innoslab amplifier with 300W average power and pulse energies in the mJ-regime

    NASA Astrophysics Data System (ADS)

    Mans, T.; Graf, R.; Dolkemeyer, J.; Schnitzler, C.

    2014-02-01

    We demonstrate a femtosecond Yb:YAG InnoSlab laser amplifier producing <3mJ pulse energy at 100kHz pulse repetition rate. The minimal pulse duration is <1ps resulting in pulse powers <3GW. High energy and high average power could be obtained with the use of chirped pulse amplification on the power amplifier end. The laser setup consists of a seed laser with 10mW average power at pulse repetition rates of 100kHz to 1MHz, a pre-amplifier stage, a highpower InnoSlab-amplifier stage and a grating based pulse compressor. This laser source is suited for pumping of OPCPA setups und parallelisation of applications in materials processing.

  9. A Large-Bandwidth, Cylindrical Offner Pulse Stretcher for a High-Average-Power, 15 Femtosecond Laser

    SciTech Connect

    Molander, W A; Bayramian, A J; Campbell, R; Cross, R R; Huete, G; Schenkel, N; Ebbers, C; Caird, J; Barty, C J; Siders, C W

    2008-09-24

    We have designed and built an all-reflective pulse stretcher based on an Offner telescope. It uses cylindrical optics to simplify alignment and reduce aberrations. The stretch is {approx}1x10{sup 5} with a bandwidth of 200 nm. The stretcher is to be part of a 10 Hz repetition rate, high-average-power, femtosecond laser. This new design compensates for dispersion in the laser by using gratings of different groove spacing in the stretcher and compressor and a spectral phase corrector plate, made by magneto-rheological finishing, within the stretcher.

  10. A high-average power femtosecond laser for synchrotron light source applications

    NASA Astrophysics Data System (ADS)

    Wilcox, R. B.; Schoenlein, R. W.

    2007-02-01

    We describe a 60W, 70fs, 20kHz Ti:sapphire CPA laser system using cryogenically-cooled amplifiers, currently operating at the Advanced Light Source at LBNL. The system consists of an oscillator, a 20 kHz regenerative preamplifier, and two power amplifiers to produce two output beams, each at 30W. Each power amp can be pumped by two 90 Watt, 10 kHz, diode-pumped, doubled YLF lasers simultaneously (for 10 kHz) or interleaved in time (for 20 kHz). The regen is pumped at 20 kHz and 60W, producing 8W output which is split between the power amps. To maintain the crystals near the thermal conductivity peak at ~50°K, we used 300 Watt cryorefrigerators mechanically decoupled from the optical table. Pulses are compressed in a quartz transmission grating compressor, to minimize thermal distortions of the phase front typical of gold coated gratings at high power density. Transmission through the compressor is >80%, using a single 100 x 100mm grating. One of the 30W output beams is used to produce 70fs electron bunches in the synchrotron light source. The other is delayed by 300ns in a 12-pass Herriot cell before amplification, to be synchronized with the short light pulse from the synchrotron.

  11. 1 W average-power 100 MHz repetition-rate 259 nm femtosecond deep ultraviolet pulse generation from ytterbium fiber amplifier.

    PubMed

    Zhou, Xiangyu; Yoshitomi, Dai; Kobayashi, Yohei; Torizuka, Kenji

    2010-05-15

    We demonstrate 1W average-power ultraviolet (UV) femtosecond (fs) ultrashort pulse generation at a wavelength of 259 nm and a repetition rate as high as 100 MHz by quadrupling a fs ytterbium-fiber laser. A cavity-enhanced design is employed for efficient frequency doubling to the UV region. The optical-to-optical efficiency of UV output to the pump diode is 2.6%. PMID:20479859

  12. Investigation of the thermally induced laser beam distortion associated with vacuum compressor gratings in high energy and high average power femtosecond laser systems.

    PubMed

    Fourmaux, S; Serbanescu, C; Lecherbourg, L; Payeur, S; Martin, F; Kieffer, J C

    2009-01-01

    We report successful compensation of the thermally induced laser beam distortion associated with high energy 110 mJ and high average power femtosecond laser system of 11 Watts operated with vacuum compressor gratings. To enhance laser-based light source brightness requires development of laser systems with higher energy and higher average power. Managing the high thermal loading on vacuum optical components is a key issue in the implementation of this approach. To our knowledge this is the first time that such thermal induced distortions on the vacuum compressor gratings are characterized and compensated. PMID:19129886

  13. Investigation of the thermally induced laser beam distortion associated with vacuum compressor gratings in high energy and high average power femtosecond laser systems

    PubMed Central

    Fourmaux, S.; Serbanescu, C.; Lecherbourg, L.; Payeur, S.; Martin, F.; Kieffer, J. C.

    2009-01-01

    We report successful compensation of the thermally induced laser beam distortion associated with high energy 110 mJ and high average power femtosecond laser system of 11 Watts operated with vacuum compressor gratings. To enhance laser-based light source brightness requires development of laser systems with higher energy and higher average power. Managing the high thermal loading on vacuum optical components is a key issue in the implementation of this approach. To our knowledge this is the first time that such thermal induced distortions on the vacuum compressor gratings are characterized and compensated. PMID:19129886

  14. Femtosecond pulses at 50-W average power from an Yb:YAG planar waveguide amplifier seeded by an Yb:KYW oscillator.

    PubMed

    Leburn, Christopher G; Ramírez-Corral, Cristtel Y; Thomson, Ian J; Hall, Denis R; Baker, Howard J; Reid, Derryck T

    2012-07-30

    We report the demonstration of a high-power single-side-pumped Yb:YAG planar waveguide amplifier seeded by an Yb:KYW femtosecond laser. Five passes through the amplifier yielded 700-fs pulses with average powers of 50 W at 1030 nm. A numerical simulation of the amplifier implied values for the laser transition saturation intensity, the small-signal intensity gain coefficient and the gain bandwidth of 10.0 kW cm(-2), 1.6 cm(-1), and 3.7 nm respectively, and identified gain-narrowing as the dominant pulse-shaping mechanism. PMID:23038288

  15. Nonlinear femtosecond pulse compression at high average power levels by use of a large-mode-area holey fiber.

    PubMed

    Südmeyer, T; Brunner, F; Innerhofer, E; Paschotta, R; Furusawa, K; Baggett, J C; Monro, T M; Richardson, D J; Keller, U

    2003-10-15

    We demonstrate that nonlinear fiber compression is possible at unprecedented average power levels by use of a large-mode-area holey (microstructured) fiber and a passively mode-locked thin disk Yb:YAG laser operating at 1030 nm. We broaden the optical spectrum of the 810-fs pump pulses by nonlinear propagation in the fiber and remove the resultant chirp with a dispersive prism pair to achieve 18 W of average power in 33-fs pulses with a peak power of 12 MW and a repetition rate of 34 MHz. The output beam is nearly diffraction limited and is linearly polarized. PMID:14587786

  16. Production of high power femtosecond terahertz radiation

    SciTech Connect

    Neil, George R.; Carr, G.L.; Gubeli III, Joseph F.; Jordan, K.; Martin, Michael C.; McKinney, Wayne R.; Shinn, Michelle; Tani, Masahiko; Williams, G.P.; Zhang, X.-C.

    2003-07-11

    The terahertz (THz) region of the electromagnetic spectrum is attracting interest for a broad range of applications ranging from diagnosing electron beams to biological imaging. Most sources of short pulse THz radiation utilize excitation of biased semiconductors or electro-optic crystals by high peak power lasers. For example, this was done by using an un-doped InAs wafer irradiated by a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. Microwatt levels of THz radiation were detected when excited with FEL pulses at 1.06 mm wavelength and 10W average power. Recently substantially higher powers of femtosecond THz pulses produced by synchrotron emission were extracted from the electron beamline. Calculations and measurements confirm the production of coherent broadband THz radiation from relativistic electrons with an average power of nearly 20W, a world record in this wavelength range by a factor of 10,000. We describe the source, presenting theoretical calculations and their experimental verification. Potential applications of this exciting new source include driving new non-linear phenomena, performing pump-probe studies of dynamical properties of novel materials, and studying molecular vibrations and rotations, low frequency protein motions, phonons, superconductor band gaps, electronic scattering, collective electronic excitations (e.g., charge density waves), and spintronics.

  17. Production of high power femtosecond terahertz radiation

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Carr, G. L.; Gubeli, Joseph F.; Jordan, K.; Martin, Michael C.; McKinney, Wayne R.; Shinn, Michelle; Tani, Masahiko; Williams, G. P.; Zhang, X.-C.

    2003-07-01

    The terahertz (THz) region of the electromagnetic spectrum is attracting interest for a broad range of applications ranging from diagnosing electron beams to biological imaging. Most sources of short pulse THz radiation utilize excitation of biased semiconductors or electro-optic crystals by high peak power lasers. For example, this was done by using an un-doped InAs wafer irradiated by a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. Microwatt levels of THz radiation were detected when excited with FEL pulses at 1.06 μm wavelength and 10 W average power. Recently substantially higher powers of femtosecond THz pulses produced by synchrotron emission were extracted from the electron beamline. Calculations and measurements confirm the production of coherent broadband THz radiation from relativistic electrons with an average power of nearly 20 W, a world record in this wavelength range by a factor of 10,000. We describe the source, presenting theoretical calculations and their experimental verification. Potential applications of this exciting new source include driving new non-linear phenomena, performing pump-probe studies of dynamical properties of novel materials, and studying molecular vibrations and rotations, low frequency protein motions, phonons, superconductor bandgaps, electronic scattering, collective electronic excitations (e.g., charge density waves), and spintronics.

  18. Diode-pumped continuous-wave and femtosecond Cr:LiCAF lasers with high average power in the near infrared, visible and near ultraviolet.

    PubMed

    Demirbas, Umit; Baali, Ilyes; Acar, Durmus Alp Emre; Leitenstorfer, Alfred

    2015-04-01

    We demonstrate continuous-wave (cw), cw frequency-doubled, cw mode-locked and Q-switched mode-locked operation of multimode diode-pumped Cr:LiCAF lasers with record average powers. Up to 2.54 W of cw output is obtained around 805 nm at an absorbed pump power of 5.5 W. Using intracavity frequency doubling with a BBO crystal, 0.9 W are generated around 402 nm, corresponding to an optical-to-optical conversion efficiency of 12%. With an intracavity birefringent tuning plate, the fundamental and frequency-doubled laser output is tuned continuously in a broad wavelength range from 745 nm to 885 nm and from 375 to 440 nm, respectively. A saturable Bragg reflector is used to initiate and sustain mode locking. In the cw mode-locked regime, the Cr:LiCAF laser produces 105-fs long pulses near 810 nm with an average power of 0.75 W. The repetition rate is 96.4 MHz, resulting in pulse energies of 7.7 nJ and peak powers of 65 kW. In Q-switched mode-locked operation, pulses with energies above 150 nJ are generated. PMID:25968727

  19. High average power pockels cell

    DOEpatents

    Daly, Thomas P.

    1991-01-01

    A high average power pockels cell is disclosed which reduces the effect of thermally induced strains in high average power laser technology. The pockels cell includes an elongated, substantially rectangular crystalline structure formed from a KDP-type material to eliminate shear strains. The X- and Y-axes are oriented substantially perpendicular to the edges of the crystal cross-section and to the C-axis direction of propagation to eliminate shear strains.

  20. High-power synchronously pumped femtosecond Raman fiber laser.

    PubMed

    Churin, D; Olson, J; Norwood, R A; Peyghambarian, N; Kieu, K

    2015-06-01

    We report a high-power synchronously pumped femtosecond Raman fiber laser operating in the normal dispersion regime. The Raman laser is pumped by a picosecond Yb(3+)-doped fiber laser. It produces highly chirped pulses with energy up to 18 nJ, average power of 0.76 W and 88% efficiency. The pulse duration is measured to be 147 fs after external compression. We observed two different regimes of operation of the laser: coherent and noise-like regime. Both regimes were experimentally characterized. Numerical simulations are in a good agreement with experimental results. PMID:26030549

  1. High-power Yb:YAG single-crystal fiber amplifiers for femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Lesparre, Fabien; Martial, Igor; Didierjean, Julien; Gomes, Jean Thomas; Pallmann, Wolfgang; Resan, Bojan; Loescher, André; Negel, Jan-Phillipp; Graf, Thomas; Abdou Ahmed, Marwan; Balembois, François; Georges, Patrick

    2015-02-01

    We describe a multi-stages single crystal fiber (SCF) amplifier for the amplification of femtosecond pulses with radial or azimuthal polarization in view of high speed material processing (surface structuring, drilling). We demonstrate a three stages diode-pumped Yb:YAG single crystal fiber amplifier to achieve femtosecond pulses at an average power of 85W at 20 MHz in radial and azimuthal polarization.

  2. High-Average Power Facilities

    SciTech Connect

    Dowell, David H.; Power, John G.; /Argonne

    2012-09-05

    There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.

  3. High average power induction accelerators

    SciTech Connect

    Swingle, J.C.

    1985-10-01

    The induction accelerator is discussed with respect to general background and concept, beam transport, scaling, pulse power technology, and the electron beam injector. A discussion of the factors which affect the scaling of the intensity of the beam is given. Limiting factors include collective forces in the beam, virtual cathode formation, surroundings, and beam breakup instability. 24 refs., 11 figs. (WRF)

  4. High Average Power Yb:YAG Laser

    SciTech Connect

    Zapata, L E; Beach, R J; Payne, S A

    2001-05-23

    We are working on a composite thin-disk laser design that can be scaled as a source of high brightness laser power for tactical engagement and other high average power applications. The key component is a diffusion-bonded composite comprising a thin gain-medium and thicker cladding that is strikingly robust and resolves prior difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emission (ASE). In contrast to high power rods or slabs, the one-dimensional nature of the cooling geometry and the edge-pump geometry scale gracefully to very high average power. The crucial design ideas have been verified experimentally. Progress this last year included: extraction with high beam quality using a telescopic resonator, a heterogeneous thin film coating prescription that meets the unusual requirements demanded by this laser architecture, thermal management with our first generation cooler. Progress was also made in design of a second-generation laser.

  5. Compact, low power radio frequency cavity for femtosecond electron microscopy

    SciTech Connect

    Lassise, A.; Mutsaers, P. H. A.; Luiten, O. J.

    2012-04-15

    Reported here is the design, construction, and characterization of a small, power efficient, tunable dielectric filled cavity for the creation of femtosecond electron bunches in an existing electron microscope without the mandatory use of femtosecond lasers. A 3 GHz pillbox cavity operating in the TM{sub 110} mode was specially designed for chopping the beam of a 30 keV scanning electron microscope. The dielectric material used is ZrTiO{sub 4}, chosen for the high relative permittivity ({epsilon}{sub r}= 37 at 10 GHz) and low loss tangent (tan {delta}= 2 x 10{sup -4}). This allows the cavity radius to be reduced by a factor of six, while the power consumption is reduced by an order of magnitude compared to a vacuum pillbox cavity. These features make this cavity ideal as a module for existing electron microscopes, and an alternative to femtosecond laser systems integrated with electron microscopes.

  6. 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.

  7. Scalability of components for kW-level average power few-cycle lasers.

    PubMed

    Hädrich, Steffen; Rothhardt, Jan; Demmler, Stefan; Tschernajew, Maxim; Hoffmann, Armin; Krebs, Manuel; Liem, Andreas; de Vries, Oliver; Plötner, Marco; Fabian, Simone; Schreiber, Thomas; Limpert, Jens; Tünnermann, Andreas

    2016-03-01

    In this paper, the average power scalability of components that can be used for intense few-cycle lasers based on nonlinear compression of modern femtosecond solid-state lasers is investigated. The key components of such a setup, namely, the gas-filled waveguides, laser windows, chirped mirrors for pulse compression and low dispersion mirrors for beam collimation, focusing, and beam steering are tested under high-average-power operation using a kilowatt cw laser. We demonstrate the long-term stable transmission of kW-level average power through a hollow capillary and a Kagome-type photonic crystal fiber. In addition, we show that sapphire substrates significantly improve the average power capability of metal-coated mirrors. Ultimately, ultrabroadband dielectric mirrors show negligible heating up to 1 kW of average power. In summary, a technology for scaling of few-cycle lasers up to 1 kW of average power and beyond is presented. PMID:26974623

  8. High power femtosecond lasers at ELI-NP

    SciTech Connect

    Dabu, Razvan

    2015-02-24

    Specifications of the high power laser system (HPLS) designed for nuclear physics experiments are presented. Configuration of the 2 × 10 PW femtosecond laser system is described. In order to reach the required laser beam parameters, advanced laser techniques are proposed for the HPLS: parametric amplification and cross-polarized wave generation for the intensity contrast improvement and spectral broadening, acousto-optic programmable filters to compensate for spectral phase dispersion, optical filters for spectrum management, combined methods for transversal laser suppression.

  9. Average power laser experiment (APLE) design

    NASA Astrophysics Data System (ADS)

    Parazzoli, C. G.; Rodenburg, R. E.; Dowell, D. H.; Greegor, R. B.; Kennedy, R. C.; Romero, J. B.; Siciliano, J. A.; Tong, K.-O.; Vetter, A. M.; Adamski, J. L.; Pistoresi, D. J.; Shoffstall, D. R.; Quimby, D. C.

    1992-07-01

    We describe the details and the design requirements for the 100 kW CW radio frequency free electron laser at 10 μm to be built at Boeing Aerospace and Electronics Division in Seattle with the collaboration of Los Alamos National Laboratory. APLE is a single-accelerator master-oscillator and power-amplifier (SAMOPA) device. The goal of this experiment is to demonstrate a fully operational RF-FEL at 10 μm with an average power of 100 kW. The approach and wavelength were chosen on the basis of maximum cost effectiveness, including utilization of existing hardware and reasonable risk, and potential for future applications. Current plans call for an initial oscillator power demonstration in the fall of 1994 and full SAMOPA operation by December 1995.

  10. High-power femtosecond pulse generation in a passively mode-locked Nd:SrLaAlO4 laser

    NASA Astrophysics Data System (ADS)

    Liu, Shan-De; Dong, Lu-Lu; Zheng, Li-He; Berkowski, Marek; Su, Liang-Bi; Ren, Ting-Qi; Peng, Yan-Dong; Hou, Jia; Zhang, Bai-Tao; He, Jing-Liang

    2016-07-01

    A high optical quality Nd:SrLaAlO4 (Nd:SLA) crystal was grown using the Czochralski method and showed broad fluorescence spectrum with a full width at half maximum value of 34 nm, which is beneficial for generating femtosecond laser pulses. A stable diode-pumped passively mode-locked femtosecond Nd:SLA laser with 458 fs pulse duration was achieved for the first time at a central wavelength of 1077.9 nm. The average output power of the continuous-wave mode-locked laser was 520 mW and the repetition rate was 78.5 MHz.

  11. Time-dependent wave packet averaged vibrational frequencies from femtosecond stimulated Raman spectra

    NASA Astrophysics Data System (ADS)

    Wu, Yue-Chao; Zhao, Bin; Lee, Soo-Y.

    2016-02-01

    Femtosecond stimulated Raman spectroscopy (FSRS) on the Stokes side arises from a third order polarization, P(3)(t), which is given by an overlap of a first order wave packet, |" separators=" Ψ2 ( 1 ) ( p u , t ) > , prepared by a narrow band (ps) Raman pump pulse, Epu(t), on the upper electronic e2 potential energy surface (PES), with a second order wave packet, <" separators=" Ψ1 ( 2 ) ( p r ∗ , p u , t ) | , that is prepared on the lower electronic e1 PES by a broadband (fs) probe pulse, Epr(t), acting on the first-order wave packet. In off-resonant FSRS, |" separators=" Ψ2 ( 1 ) ( p u , t ) > resembles the zeroth order wave packet |" separators=" Ψ1 ( 0 ) ( t ) > on the lower PES spatially, but with a force on |" separators=" Ψ2 ( 1 ) ( p u , t ) > along the coordinates of the reporter modes due to displacements in the equilibrium position, so that <" separators=" Ψ1 ( 2 ) ( p r ∗ , p u , t ) | will oscillate along those coordinates thus giving rise to similar oscillations in P(3)(t) with the frequencies of the reporter modes. So, by recovering P(3)(t) from the FSRS spectrum, we are able to deduce information on the time-dependent quantum-mechanical wave packet averaged frequencies, ω ¯ j ( t ) , of the reporter modes j along the trajectory of |" separators=" Ψ1 ( 0 ) ( t ) > . The observable FSRS Raman gain is related to the imaginary part of P(3)(ω). The imaginary and real parts of P(3)(ω) are related by the Kramers-Kronig relation. Hence, from the FSRS Raman gain, we can obtain the complex P(3)(ω), whose Fourier transform then gives us the complex P(3)(t) to analyze for ω ¯ j ( t ) . We apply the theory, first, to a two-dimensional model system with one conformational mode of low frequency and one reporter vibrational mode of higher frequency with good results, and then we apply it to the time-resolved FSRS spectra of the cis-trans isomerization of retinal in rhodopsin [P. Kukura et al., Science 310, 1006 (2005)]. We obtain the vibrational

  12. Extended femtosecond laser wavelength range to 330 nm in a high power LBO based optical parametric oscillator.

    PubMed

    Fan, Jintao; Gu, Chenglin; Wang, Chingyue; Hu, Minglie

    2016-06-13

    We experimentally demonstrate a compact tunable, high average power femtosecond laser source in the ultraviolet (UV) regime. The laser source is based on intra-cavity frequency doubling of a temperature-tuned lithium tribotate (LBO) optical parametric oscillator (OPO), synchronously pumped at 520 nm by a frequency-doubled, Yb-fiber femtosecond laser amplifier system. By adjusting crystal temperature, the OPO can provide tunable visible to near-infrared (NIR) signal pulse, which have a wide spectral tuning range from 660 to 884 nm. Using a β-barium borate (BBO) crystal for intra-cavity frequency doubling, tunable femtosecond UV pulse are generated across 330~442 nm with up to 364 mW at 402 nm. PMID:27410342

  13. Absence of amorphous phase in high power femtosecond laser-ablated silicon

    SciTech Connect

    Rogers, Matthew S.; Grigoropoulos, Costas P.; Minor, Andrew M.; Mao, Samuel S.

    2009-01-05

    As femtosecond lasers emerge as viable tools for advanced microscale materials processing, it becomes increasingly important to understand the characteristics of materials resulting from femtosecond laser microablation or micromachining. We conducted transmission electron microscopy experiments to investigate crater structures in silicon produced by repetitive high power femtosecond laser ablation. Comparable experiments of nanosecond laser ablation of silicon were also performed. We found that an amorphous silicon layer that is typically produced in nanosecond laser ablation is absent when the material is irradiated by high power femtosecond laser pulses. Instead, only a defective single crystalline layer was observed in the high power femtosecond laser-ablated silicon crater. Possible mechanisms underlying the formation of the defective single crystalline phase are discussed.

  14. New generation of high average power industry grade ultrafast ytterbium fiber lasers

    NASA Astrophysics Data System (ADS)

    Yusim, Alex; Samartsev, Igor; Shkurikhin, Oleg; Myasnikov, Daniil; Bordenyuk, Andrey; Platonov, Nikolai; Kancharla, Vijay; Gapontsev, Valentin

    2016-03-01

    We report an industrial grade picosecond and femtosecond pulse Yb fiber lasers with >100 μJ pulse energy and hundreds of Watts of average power for improved laser machining speed of sapphire and glass. This highly efficient laser offers >25% wall plug efficiency within a compact 3U rack-mountable configuration plus a long >2m fiber delivery cable. Reconfigurable features such as controllable repetition rate, fine pulse duration control, burst mode operation and adjustable pulse energy permit the customer to tailor the laser to their application.

  15. High-power Yb:YAG single-crystal fiber amplifiers for femtosecond lasers in cylindrical polarization.

    PubMed

    Lesparre, Fabien; Gomes, Jean Thomas; Délen, Xavier; Martial, Igor; Didierjean, Julien; Pallmann, Wolfgang; Resan, Bojan; Eckerle, Michael; Graf, Thomas; Abdou Ahmed, Marwan; Druon, Frederic; Balembois, François; Georges, Patrick

    2015-06-01

    We demonstrate a three-stage diode-pumped Yb:YAG single-crystal-fiber amplifier to generate femtosecond pulses at high average powers with linear or cylindrical (i.e., radial or azimuthal) polarization. At a repetition rate of 20 MHz, 750-fs pulses were obtained at an average power of 85 W in cylindrical polarization and at 100 W in linear polarization. The report includes investigations on the use of Yb:YAG single-crystal fibers with different length/doping ratio and the zero-phonon pumping at a wavelength of 969 nm in order to optimize the performance. PMID:26030546

  16. High average power switching in diamond

    SciTech Connect

    Hofer, W.W.; Schoenbach, K.H.

    1992-06-01

    Diamond has many properties which make it ideal for a high power solid-state switch. The crystal structure of diamond is relatively well characterized. It is a semiconductor with a band-gap of 5.5 eV at 300{degree}K. The high band-gap of diamond results in a small dark current compared to Si or GaAs. As a result the breakdown field or holding voltage is very high, 1--10 MV/cm. The electron and hole mobility are approximately 2000 cm{sup 2}/v-sec. At room temperature, diamond has the highest thermal conductivity of any solid, 20 W/{degree}K -cm, about five times that of copper. This is ideal for switching because heat dissipation and thermal runaway problems are greatly mitigated. Our switch concept uses a low current (power on-off switch. Steady advancements in CVD polycrystalline and single crystal diamond help make this possible.

  17. High average power switching in diamond

    SciTech Connect

    Hofer, W.W. ); Schoenbach, K.H. )

    1992-06-01

    Diamond has many properties which make it ideal for a high power solid-state switch. The crystal structure of diamond is relatively well characterized. It is a semiconductor with a band-gap of 5.5 eV at 300[degree]K. The high band-gap of diamond results in a small dark current compared to Si or GaAs. As a result the breakdown field or holding voltage is very high, 1--10 MV/cm. The electron and hole mobility are approximately 2000 cm[sup 2]/v-sec. At room temperature, diamond has the highest thermal conductivity of any solid, 20 W/[degree]K -cm, about five times that of copper. This is ideal for switching because heat dissipation and thermal runaway problems are greatly mitigated. Our switch concept uses a low current (power on-off switch. Steady advancements in CVD polycrystalline and single crystal diamond help make this possible.

  18. 152 W average power Tm-doped fiber CPA system.

    PubMed

    Stutzki, Fabian; Gaida, Christian; Gebhardt, Martin; Jansen, Florian; Wienke, Andreas; Zeitner, Uwe; Fuchs, Frank; Jauregui, Cesar; Wandt, Dieter; Kracht, Dietmar; Limpert, Jens; Tünnermann, Andreas

    2014-08-15

    A high-power thulium (Tm)-doped fiber chirped-pulse amplification system emitting a record compressed average output power of 152 W and 4 MW peak power is demonstrated. This result is enabled by utilizing Tm-doped photonic crystal fibers with mode-field diameters of 35 μm, which mitigate detrimental nonlinearities, exhibit slope efficiencies of more than 50%, and allow for reaching a pump-power-limited average output power of 241 W. The high-compression efficiency has been achieved by using multilayer dielectric gratings with diffraction efficiencies higher than 98%. PMID:25121845

  19. Optimization of high average power FEL beam for EUV lithography

    NASA Astrophysics Data System (ADS)

    Endo, Akira

    2015-05-01

    Extreme Ultraviolet Lithography (EUVL) is entering into high volume manufacturing (HVM) stage, with high average power (250W) EUV source from laser produced plasma at 13.5nm. Semiconductor industry road map indicates a scaling of the source technology more than 1kW average power by high repetition rate FEL. This paper discusses on the lowest risk approach to construct a prototype based on superconducting linac and normal conducting undulator, to demonstrate a high average power 13.5nm FEL equipped with optimized optical components and solid state lasers, to study FEL application in EUV lithography.

  20. High-power directly diode-pumped femtosecond Yb:KGW lasers with optimized parameters

    NASA Astrophysics Data System (ADS)

    Kim, G. H.; Yang, J.; Kulik, A. V.; Sall, E. G.; Chizhov, S. A.; Yashin, V. E.; Kang, U.

    2014-02-01

    We report a diode-pumped Yb:KGW laser that is capable of operating as a Q-switched oscillator or as a regenerative amplifier with average power of more than 20 W. The laser is based on a dual-crystal configuration where the pump thermal load is distributed over relatively long two crystals. It permits a sufficiently large number of passes with low passive losses and maximizes the energy extraction efficiency. The amplification bandwidth was extended by spectral combining of two Yb:KGW crystals with spectrally shifted gain maxima, that allows to mitigate spectral gain narrowing and provides pulse length down to 200 fs after compression in a stretcher-compressor module. The output power saturated with increasing pump power and output beam quality was defined by aberration of thermal lenses. Optimization of laser cavity allows us to compensate thermal lens partially and provide output beams with quality M2<1.2. Efficient frequency doubling and tripling of high-power femtosecond Yb:KGW laser is demonstrated in a nonlinear BBO crystal. Second or third harmonic generation with respective conversion efficiency of 55% or 24% was achieved in a single-pass configuration.

  1. Average refractive powers of an alexandrite laser rod

    NASA Astrophysics Data System (ADS)

    Driedger, K. P.; Krause, W.; Weber, H.

    1986-04-01

    The average refractive powers (average inverse focal lengths) of the thermal lens produced by an alexandrite laser rod optically pumped at repetition rates between 0.4 and 10 Hz and with electrical flashlamp input pulse energies up to 500 J have been measured. The measuring setup is described and the measurement results are discussed.

  2. Femtosecond high-power quantum dot vertical external cavity surface emitting laser.

    PubMed

    Hoffmann, Martin; Sieber, Oliver D; Wittwer, Valentin J; Krestnikov, Igor L; Livshits, Daniil A; Barbarin, Yohan; Südmeyer, Thomas; Keller, Ursula

    2011-04-25

    We report on the first femtosecond vertical external cavity surface emitting laser (VECSEL) exceeding 1 W of average output power. The VECSEL is optically pumped, based on self-assembled InAs quantum dot (QD) gain layers, cooled efficiently using a thin disk geometry and passively modelocked with a fast quantum dot semiconductor saturable absorber mirror (SESAM). We developed a novel gain structure with a flat group delay dispersion (GDD) of ± 10 fs2 over a range of 30 nm around the designed operation wavelength of 960 nm. This amount of GDD is several orders of magnitude lower compared to standard designs. Furthermore, we used an optimized positioning scheme of 63 QD gain layers to broaden and flatten the spectral gain. For stable and self-starting pulse formation, we have employed a QD-SESAM with a fast absorption recovery time of around 500 fs. We have achieved 1 W of average output power with 784-fs pulse duration at a repetition rate of 5.4 GHz. The QD-SESAM and the QD-VECSEL are operated with similar cavity mode areas, which is beneficial for higher repetition rates and the integration of both elements into a modelocked integrated external-cavity surface emitting laser (MIXSEL). PMID:21643061

  3. High power, single mode, all-fiber source of femtosecond pulses at 1550 nm and its use in supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Nicholson, Jeffrey W.; Yablon, A. D.; Westbrook, P. S.; Feder, K. S.; Yan, M. F.

    2004-06-01

    We present a source of high power femtosecond pulses at 1550 nm with compressed pulses at the end of a single mode fiber (SMF) pigtail. The system generates 34 femtosecond pulses at a repetition rate of 46 MHz, with average powers greater than 400 mW. The pulses are generated in a passively modelocked, erbium-doped fiber laser, and amplified in a short, erbium-doped fiber amplifier. The output of the fiber amplifier consists of highly chirped picosecond pulses. These picosecond pulses are then compressed in standard single mode fiber. While the compressed pulses in the SMF pigtail do show a low pedestal that could be avoided with the use of bulk-optic compression, the desire to compress the pulses in SMF is motivated by the ability to splice the single mode fiber to a nonlinear fiber, for continuum generation applications. We demonstrate that with highly nonlinear dispersion shifted fiber (HNLF) fusion spliced directly to the amplifier output, we generate a supercontinuum spectrum that spans more than an octave, with an average power 400 mW. Such a high power, all-fiber supercontinuum source has many important applications including frequency metrology and bio-medical imaging.

  4. High-power single-mode all-fiber femtosecond laser system and its use in continuum generation

    NASA Astrophysics Data System (ADS)

    Nicholson, Jeffrey W.; Yan, Man F.; Yablon, Andrew D.; Westbrook, Paul S.; Feder, Ken S.

    2004-10-01

    We present a source of high power femtosecond pulses at 1550 nm generating compressed pulses at the end of a single mode fiber pigtail. The system generates sub 35 femtosecond pulses at a repetition rate of 50 MHz, with average powers greater than 400 mW. The pulses are generated in a passively modelocked, erbium doped fiber laser, and amplified in a short, erbium doped amplifier. The output of the fiber amplifier consists of highly chirped picosecond pulses. These picosecond pulses are then compressed in standard single mode fiber. While the compressed pulses in the SMF pigtail do show a low pedestal that could be avoided with the use of bulk-optic compression the desire to compress the pulses in SMF is motivated by the ability to splice the single mode fiber to a nonlinear fiber, for continuum generation applications. We demonstrate that with highly nonlinear dispersion shifted fiber (HNLF) fusion spliced directly to the amplifier output, we generate a supercontinuum spectrum that spans more than an octave, with an average power 350 mW. Such a high power, all-fiber supercontinuum source has many important applications including frequency metrology and biomedical imaging.

  5. High power, single mode, all-fiber source of femtosecond pulses at 1550 nm and its use in supercontinuum generation.

    PubMed

    Nicholson, Jeffrey; Yablon, A; Westbrook, P; Feder, K; Yan, M

    2004-06-28

    We present a source of high power femtosecond pulses at 1550 nm with compressed pulses at the end of a single mode fiber (SMF) pigtail. The system generates 34 femtosecond pulses at a repetition rate of 46 MHz, with average powers greater than 400 mW. The pulses are generated in a passively modelocked, erbium-doped fiber laser, and amplified in a short, erbium-doped fiber amplifier. The output of the fiber amplifier consists of highly chirped picosecond pulses. These picosecond pulses are then compressed in standard single mode fiber. While the compressed pulses in the SMF pigtail do show a low pedestal that could be avoided with the use of bulk-optic compression, the desire to compress the pulses in SMF is motivated by the ability to splice the single mode fiber to a nonlinear fiber, for continuum generation applications. We demonstrate that with highly nonlinear dispersion shifted fiber (HNLF) fusion spliced directly to the amplifier output, we generate a supercontinuum spectrum that spans more than an octave, with an average power 400 mW. Such a high power, all-fiber supercontinuum source has many important applications including frequency metrology and bio-medical imaging. PMID:19483820

  6. High average power scaleable thin-disk laser

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Payne, Stephen A.; Powell, Howard; Krupke, William F.; Sutton, Steven B.

    2002-01-01

    Using a thin disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high average output power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high average power laser for material processing applications as well as for weapon and air defense applications.

  7. Process optimization in high-average-power ultrashort pulse laser microfabrication: how laser process parameters influence efficiency, throughput and quality

    NASA Astrophysics Data System (ADS)

    Schille, Joerg; Schneider, Lutz; Loeschner, Udo

    2015-09-01

    In this paper, laser processing of technical grade stainless steel and copper using high-average-power ultrashort pulse lasers is studied in order to gain deeper insight into material removal for microfabrication. A high-pulse repetition frequency picosecond and femtosecond laser is used in conjunction with high-performance galvanometer scanners and an in-house developed two-axis polygon scanner system. By varying the processing parameters such as wavelength, pulse length, fluence and repetition rate, cavities of standardized geometry are fabricated and analyzed. From the depths of the cavities produced, the ablation rate and removal efficiency are estimated. In addition, the quality of the cavities is evaluated by means of scanning electron microscope micrographs or rather surface roughness measurements. From the results obtained, the influence of the machining parameters on material removal and machining quality is discussed. In addition, it is shown that both material removal rate and quality increase by using femtosecond compared to picosecond laser pulses. On stainless steel, a maximum throughput of 6.81 mm3/min is achieved with 32 W femtosecond laser powers; if using 187 W picosecond laser powers, the maximum is 15.04 mm3/min, respectively. On copper, the maximum throughputs are 6.1 mm3/min and 21.4 mm3/min, obtained with 32 W femtosecond and 187 W picosecond laser powers. The findings indicate that ultrashort pulses in the mid-fluence regime yield most efficient material removal. In conclusion, from the results of this analysis, a range of optimum processing parameters are derived feasible to enhance machining efficiency, throughput and quality in high-rate micromachining. The work carried out here clearly opens the way to significant industrial applications.

  8. High average power diode pumped solid state lasers for CALIOPE

    SciTech Connect

    Comaskey, B.; Halpin, J.; Moran, B.

    1994-07-01

    Diode pumping of solid state media offers the opportunity for very low maintenance, high efficiency, and compact laser systems. For remote sensing, such lasers may be used to pump tunable non-linear sources, or if tunable themselves, act directly or through harmonic crystals as the probe. The needs of long range remote sensing missions require laser performance in the several watts to kilowatts range. At these power performance levels, more advanced thermal management technologies are required for the diode pumps. The solid state laser design must now address a variety of issues arising from the thermal loads, including fracture limits, induced lensing and aberrations, induced birefringence, and laser cavity optical component performance degradation with average power loading. In order to highlight the design trade-offs involved in addressing the above issues, a variety of existing average power laser systems are briefly described. Included are two systems based on Spectra Diode Laboratory`s water impingement cooled diode packages: a two times diffraction limited, 200 watt average power, 200 Hz multi-rod laser/amplifier by Fibertek, and TRW`s 100 watt, 100 Hz, phase conjugated amplifier. The authors also present two laser systems built at Lawrence Livermore National Laboratory (LLNL) based on their more aggressive diode bar cooling package, which uses microchannel cooler technology capable of 100% duty factor operation. They then present the design of LLNL`s first generation OPO pump laser for remote sensing. This system is specified to run at 100 Hz, 20 nsec pulses each with 300 mJ, less than two times diffraction limited, and with a stable single longitudinal mode. The performance of the first testbed version will be presented. The authors conclude with directions their group is pursuing to advance average power lasers. This includes average power electro-optics, low heat load lasing media, and heat capacity lasers.

  9. HIGH AVERAGE POWER UV FREE ELECTRON LASER EXPERIMENTS AT JLAB

    SciTech Connect

    Douglas, David; Evtushenko, Pavel; Gubeli, Joseph; Hernandez-Garcia, Carlos; Legg, Robert; Neil, George; Powers, Thomas; Shinn, Michelle D; Tennant, Christopher; Williams, Gwyn

    2012-07-01

    Having produced 14 kW of average power at {approx}2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.

  10. High-average-power diode-pumped Yb: YAG lasers

    SciTech Connect

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B

    1999-10-01

    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  11. High average power supercontinuum generation in a fluoroindate fiber

    NASA Astrophysics Data System (ADS)

    Swiderski, J.; Théberge, F.; Michalska, M.; Mathieu, P.; Vincent, D.

    2014-01-01

    We report the first demonstration of Watt-level supercontinuum (SC) generation in a step-index fluoroindate (InF3) fiber pumped by a 1.55 μm fiber master-oscillator power amplifier (MOPA) system. The SC is generated in two steps: first ˜1 ns amplified laser diode pulses are broken up into soliton-like sub-pulses leading to initial spectrum extension and then launched into a fluoride fiber to obtain further spectral broadening. The pump MOPA system can operate at a changeable repetition frequency delivering up to 19.2 W of average power at 2 MHz. When the 8-m long InF3 fiber was pumped with 7.54 W at 420 kHz, output average SC power as high as 2.09 W with 27.8% of slope efficiency was recorded. The achieved SC spectrum spread from 1 to 3.05 μm.

  12. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given. PMID:23455291

  13. Kilowatt average-power laser for subpicosecond materials processing

    NASA Astrophysics Data System (ADS)

    Benson, Stephen V.; Neil, George R.; Bohn, Courtlandt L.; Biallas, George; Douglas, David; Dylla, H. Frederick; Fugitt, Jock; Jordan, Kevin; Krafft, Geoffrey; Merminga, Lia; Preble, Joe; Shinn, Michelle D.; Siggins, Tim; Walker, Richard; Yunn, Byung

    2000-04-01

    The performance of laser pulses in the sub-picosecond range for materials processing is substantially enhanced over similar fluences delivered in longer pulses. Recent advances in the development of solid state lasers have progressed significantly toward the higher average powers potentially useful for many applications. Nonetheless, prospects remain distant for multi-kilowatt sub-picosecond solid state systems such as would be required for industrial scale surface processing of metals and polymers. We present operation results from the world's first kilowatt scale ultra-fast materials processing laser. A Free Electron Laser (FEL) called the IR Demo is operational as a User Facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. In its initial operation at high average power it is capable of wavelengths in the 2 to 6 micron range and can produce approximately 0.7 ps pulses in a continuous train at approximately 75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades in the near future will extend operation beyond 10 kW CW average power in the near IR and kilowatt levels of power at wavelengths from 0.3 to 60 microns. This paper will cover the design and performance of this groundbreaking laser and operational aspects of the User Facility.

  14. High Average Power, High Energy Short Pulse Fiber Laser System

    SciTech Connect

    Messerly, M J

    2007-11-13

    Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

  15. Microchannel heatsinks for high average power laser diode arrays

    SciTech Connect

    Beach, R.; Benett, B.; Freitas, B.; Ciarlo, D.; Sperry, V.; Comaskey, B.; Emanuel, M.; Solarz, R.; Mundinger, D.

    1992-01-01

    Detailed performance results and fabrication techniques for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or even CW operation of fully filled laser diode arrays is enabled at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using a photolithographic pattern definition procedure followed by anisotropic chemical etching. A modular rack-and-stack architecture is adopted for the heatsink design allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel cooled heatsinks is ideally suited to pump array requirements for high average power crystalline lasers because of the stringent temperature demands that result from coupling the diode light to several nanometers wide absorption features characteristic of leasing ions in crystals.

  16. An Advanced Time Averaging Modelling Technique for Power Electronic Circuits

    NASA Astrophysics Data System (ADS)

    Jankuloski, Goce

    For stable and efficient performance of power converters, a good mathematical model is needed. This thesis presents a new modelling technique for DC/DC and DC/AC Pulse Width Modulated (PWM) converters. The new model is more accurate than the existing modelling techniques such as State Space Averaging (SSA) and Discrete Time Modelling. Unlike the SSA model, the new modelling technique, the Advanced Time Averaging Model (ATAM) includes the averaging dynamics of the converter's output. In addition to offering enhanced model accuracy, application of linearization techniques to the ATAM enables the use of conventional linear control design tools. A controller design application demonstrates that a controller designed based on the ATAM outperforms one designed using the ubiquitous SSA model. Unlike the SSA model, ATAM for DC/AC augments the system's dynamics with the dynamics needed for subcycle fundamental contribution (SFC) calculation. This allows for controller design that is based on an exact model.

  17. Power Efficiency Improvements through Peak-to-Average Power Ratio Reduction and Power Amplifier Linearization

    NASA Astrophysics Data System (ADS)

    Chen, Ning; Zhou, G. Tong; Qian, Hua

    2007-12-01

    Many modern communication signal formats, such as orthogonal frequency-division multiplexing (OFDM) and code-division multiple access (CDMA), have high peak-to-average power ratios (PARs). A signal with a high PAR not only is vulnerable in the presence of nonlinear components such as power amplifiers (PAs), but also leads to low transmission power efficiency. Selected mapping (SLM) and clipping are well-known PAR reduction techniques. We propose to combine SLM with threshold clipping and digital baseband predistortion to improve the overall efficiency of the transmission system. Testbed experiments demonstrate the effectiveness of the proposed approach.

  18. Yb:YAG single crystal fiber power amplifier for femtosecond sources.

    PubMed

    Délen, Xavier; Zaouter, Yoann; Martial, Igor; Aubry, Nicolas; Didierjean, Julien; Hönninger, Clemens; Mottay, Eric; Balembois, François; Georges, Patrick

    2013-01-15

    We demonstrate a versatile femtosecond power amplifier using a Yb:YAG single crystal fiber operating from 10 kHz to 10 MHz. For a total pump power of 75 W, up to 30 W is generated from the double-pass power amplifier. At a repetition rate of 10 kHz, an output energy of 1 mJ is obtained after recompression. In this configuration, the pulse duration is 380 fs, corresponding to a peak power of 2.2 GW. The M2 beam quality factor is better than 1.1 for investigated parameters. PMID:23454931

  19. Nonlinear femtosecond pump-probe spectroscopy using a power-encoded soliton delay line.

    PubMed

    Saint-Jalm, Sarah; Andresen, Esben Ravn; Bendahmane, Abdelkrim; Kudlinski, Alexandre; Rigneault, Hervé

    2016-01-01

    We show femtosecond time-resolved nonlinear pump-probe spectroscopy using a fiber soliton as the probe pulse. Furthermore, we exploit soliton dynamics to record an entire transient trace with a power-encoded delay sweep. The power-encoded delay line takes advantage of the dependency of the soliton trajectory in the (λ,z) space upon input power; the difference in accumulated group delay between trajectories converts a fast power sweep into a fast delay sweep. We demonstrate the concept by performing transient absorption spectroscopy in a test sample and validate it against a conventional pump-probe setup. PMID:26696172

  20. Optical Parametric Amplification for High Peak and Average Power

    SciTech Connect

    Jovanovic, I

    2001-11-26

    Optical parametric amplification is an established broadband amplification technology based on a second-order nonlinear process of difference-frequency generation (DFG). When used in chirped pulse amplification (CPA), the technology has been termed optical parametric chirped pulse amplification (OPCPA). OPCPA holds a potential for producing unprecedented levels of peak and average power in optical pulses through its scalable ultrashort pulse amplification capability and the absence of quantum defect, respectively. The theory of three-wave parametric interactions is presented, followed by a description of the numerical model developed for nanosecond pulses. Spectral, temperature and angular characteristics of OPCPA are calculated, with an estimate of pulse contrast. An OPCPA system centered at 1054 nm, based on a commercial tabletop Q-switched pump laser, was developed as the front end for a large Nd-glass petawatt-class short-pulse laser. The system does not utilize electro-optic modulators or multi-pass amplification. The obtained overall 6% efficiency is the highest to date in OPCPA that uses a tabletop commercial pump laser. The first compression of pulses amplified in highly nondegenerate OPCPA is reported, with the obtained pulse width of 60 fs. This represents the shortest pulse to date produced in OPCPA. Optical parametric amplification in {beta}-barium borate was combined with laser amplification in Ti:sapphire to produce the first hybrid CPA system, with an overall conversion efficiency of 15%. Hybrid CPA combines the benefits of high gain in OPCPA with high conversion efficiency in Ti:sapphire to allow significant simplification of future tabletop multi-terawatt sources. Preliminary modeling of average power limits in OPCPA and pump laser design are presented, and an approach based on cascaded DFG is proposed to increase the average power beyond the single-crystal limit. Angular and beam quality effects in optical parametric amplification are modeled

  1. Using Bayes Model Averaging for Wind Power Forecasts

    NASA Astrophysics Data System (ADS)

    Preede Revheim, Pål; Beyer, Hans Georg

    2014-05-01

    For operational purposes predictions of the forecasts of the lumped output of groups of wind farms spread over larger geographic areas will often be of interest. A naive approach is to make forecasts for each individual site and sum them up to get the group forecast. It is however well documented that a better choice is to use a model that also takes advantage of spatial smoothing effects. It might however be the case that some sites tends to more accurately reflect the total output of the region, either in general or for certain wind directions. It will then be of interest giving these a greater influence over the group forecast. Bayesian model averaging (BMA) is a statistical post-processing method for producing probabilistic forecasts from ensembles. Raftery et al. [1] show how BMA can be used for statistical post processing of forecast ensembles, producing PDFs of future weather quantities. The BMA predictive PDF of a future weather quantity is a weighted average of the ensemble members' PDFs, where the weights can be interpreted as posterior probabilities and reflect the ensemble members' contribution to overall forecasting skill over a training period. In Revheim and Beyer [2] the BMA procedure used in Sloughter, Gneiting and Raftery [3] were found to produce fairly accurate PDFs for the future mean wind speed of a group of sites from the single sites wind speeds. However, when the procedure was attempted applied to wind power it resulted in either problems with the estimation of the parameters (mainly caused by longer consecutive periods of no power production) or severe underestimation (mainly caused by problems with reflecting the power curve). In this paper the problems that arose when applying BMA to wind power forecasting is met through two strategies. First, the BMA procedure is run with a combination of single site wind speeds and single site wind power production as input. This solves the problem with longer consecutive periods where the input data

  2. Thermal management in high average power pulsed compression systems

    SciTech Connect

    Wavrik, R.W.; Reed, K.W.; Harjes, H.C.; Weber, G.J.; Butler, M.; Penn, K.J.; Neau, E.L.

    1992-08-01

    High average power repetitively pulsed compression systems offer a potential source of electron beams which may be applied to sterilization of wastes, treatment of food products, and other environmental and consumer applications. At Sandia National Laboratory, the Repetitive High Energy Pulsed Power (RHEPP) program is developing a 7 stage magnetic pulse compressor driving a linear induction voltage adder with an electron beam diode load. The RHEPP machine is being design to deliver 350 kW of average power to the diode in 60 ns FWHM, 2.5 MV, 3 kJ pulses at a repetition rate of 120 Hz. In addition to the electrical design considerations, the repetition rate requires thermal management of the electrical losses. Steady state temperatures must be kept below the material degradation temperatures to maximize reliability and component life. The optimum design is a trade off between thermal management, maximizing overall electrical performance of the system, reliability, and cost effectiveness. Cooling requirements and configurations were developed for each of the subsystems of RHEPP. Finite element models that combine fluid flow and heat transfer were used to screen design concepts. The analysis includes one, two, and three dimensional heat transfer using surface heat transfer coefficients and boundary layer models. Experiments were conducted to verify the models as well as to evaluate cooling channel fabrication materials and techniques in Metglas wound cores. 10 refs.

  3. Thermal management in high average power pulsed compression systems

    SciTech Connect

    Wavrik, R.W.; Reed, K.W.; Harjes, H.C.; Weber, G.J.; Butler, M.; Penn, K.J.; Neau, E.L.

    1992-01-01

    High average power repetitively pulsed compression systems offer a potential source of electron beams which may be applied to sterilization of wastes, treatment of food products, and other environmental and consumer applications. At Sandia National Laboratory, the Repetitive High Energy Pulsed Power (RHEPP) program is developing a 7 stage magnetic pulse compressor driving a linear induction voltage adder with an electron beam diode load. The RHEPP machine is being design to deliver 350 kW of average power to the diode in 60 ns FWHM, 2.5 MV, 3 kJ pulses at a repetition rate of 120 Hz. In addition to the electrical design considerations, the repetition rate requires thermal management of the electrical losses. Steady state temperatures must be kept below the material degradation temperatures to maximize reliability and component life. The optimum design is a trade off between thermal management, maximizing overall electrical performance of the system, reliability, and cost effectiveness. Cooling requirements and configurations were developed for each of the subsystems of RHEPP. Finite element models that combine fluid flow and heat transfer were used to screen design concepts. The analysis includes one, two, and three dimensional heat transfer using surface heat transfer coefficients and boundary layer models. Experiments were conducted to verify the models as well as to evaluate cooling channel fabrication materials and techniques in Metglas wound cores. 10 refs.

  4. Highly flexible ultrafast laser system with 260W average power

    NASA Astrophysics Data System (ADS)

    Mans, Tl; Dolkemeyer, Jan; Russbüldt, P.; Schnitzler, Claus

    2011-02-01

    A flexible ultrafast laser amplifier system based on Ytterbium Innoslab technology with an average power exceeding 200W is presented. The pulse duration of the system can be continuously tuned between 500fs and 6ps, limited only by the amplification bandwidth of Yb:YAG and the stretcher of the seed source. The repetition rate can be varied from 26.6MHz down to 1MHz. For the ps-regime more than 200μJ and for the fs-regime more than 50μJ are demonstrated without the need of temporal compression of the high power beam after the amplifier. Spectral bandwidth is close to the transform limit of the shortest measured pulses. Beam quality is measured to be near the diffraction limit (M2<1.3).

  5. A high-average-power FEL for industrial applications

    SciTech Connect

    Dylla, H.F.; Benson, S.; Bisognano, J.

    1995-12-31

    CEBAF has developed a comprehensive conceptual design of an industrial user facility based on a kilowatt UV (150-1000 nm) and IR (2-25 micron) FEL driven by a recirculating, energy-recovering 200 MeV superconducting radio-frequency (SRF) accelerator. FEL users{endash}CEBAF`s partners in the Laser Processing Consortium, including AT&T, DuPont, IBM, Northrop-Grumman, 3M, and Xerox{endash}plan to develop applications such as polymer surface processing, metals and ceramics micromachining, and metal surface processing, with the overall effort leading to later scale-up to industrial systems at 50-100 kW. Representative applications are described. The proposed high-average-power FEL overcomes limitations of conventional laser sources in available power, cost-effectiveness, tunability and pulse structure. 4 refs., 3 figs., 2 tabs.

  6. Some results of the propagation of the high-power terawatt femtosecond laser radiation in different media

    NASA Astrophysics Data System (ADS)

    Babushkin, P. A.; Burnashov, A. V.; Iglakova, A. N.; Kovaleva, S. F.; Medvedenko, I. A.

    2015-12-01

    The results of laboratory experiments and numerical calculation of propagation of high-power terawatt femtosecond laser radiation via different media (air, glass and water) are represented. The experiments have been made on femtosecond Ti:Sa-laser system of IAO SB RAS. The spatial features of high-power terawatt femtosecond laser radiation are presented also. The ability of control of the position of the beginning of the field filamentation and angle of divergence of supercontinuum on high-power terawatt femtosecond laser radiation via plane parallel plate (glass) are found. The values of the location of the high value of the backscattering depending on filamentation conditions and the characteristics of supercontinuum and lidar system are obtained. The ability of the remote sensing of cirrus clouds with the help of high-power terawatt femtosecond laser radiation is discussed. The results of interactions of high-power terawatt femtosecond laser radiation and ice hexagonal plate crystal depending upon location of this crystal and filamentation conditions are represented.

  7. Potential of high-average-power solid state lasers

    SciTech Connect

    Emmett, J.L.; Krupke, W.F.; Sooy, W.R.

    1984-09-25

    We discuss the possibility of extending solid state laser technology to high average power and of improving the efficiency of such lasers sufficiently to make them reasonable candidates for a number of demanding applications. A variety of new design concepts, materials, and techniques have emerged over the past decade that, collectively, suggest that the traditional technical limitations on power (a few hundred watts or less) and efficiency (less than 1%) can be removed. The core idea is configuring the laser medium in relatively thin, large-area plates, rather than using the traditional low-aspect-ratio rods or blocks. This presents a large surface area for cooling, and assures that deposited heat is relatively close to a cooled surface. It also minimizes the laser volume distorted by edge effects. The feasibility of such configurations is supported by recent developments in materials, fabrication processes, and optical pumps. Two types of lasers can, in principle, utilize this sheet-like gain configuration in such a way that phase and gain profiles are uniformly sampled and, to first order, yield high-quality (undistorted) beams. The zig-zag laser does this with a single plate, and should be capable of power levels up to several kilowatts. The disk laser is designed around a large number of plates, and should be capable of scaling to arbitrarily high power levels.

  8. The development of a high average power glass laser source

    NASA Astrophysics Data System (ADS)

    Myers, J. D.

    1984-05-01

    The subject contract has as its objective the development of a high average power glass laser by systematically improving the factors which influence the ability of a laser glass to handle large power levels. Based upon the availability of the thermal laser glass composition Q-100, the rationale used was toward the improvement of the efficiency of a glass laser by developing methods to increase the pumping efficiency and toward the improvement of the power handling capability of the glass laser rod itself. These incremental developments were broken down as follows: (1) Characterization of Q-100 Laser Glass: The measurement of its thermo-physical and thermo-optical properties to better define its engineering design parameters. (2) Improve Pumping Efficiency or Q-100: Primarily by cladding Q-100 with a matching cladding glass which would act as a lens and improve the transfer of pumping energy from the flashlamp. (3) Reduce thermal loading of Q-100 by Selective filtering of the flashlamp radiation and/or use energy transfer schemes to increase that portion of the flashlamp radiation corresponding to the neodymium pump bands. (4) Increase the rupture strength of Q-100 to directly increase its power-handling capability. (5) Investigate alternate pump sources to improve efficiency.

  9. A high average power electro-optic switch using KTP

    SciTech Connect

    Ebbers, C.A.; Cook, W.M.; Velsko, S.P.

    1994-04-01

    High damage threshold, high thermal conductivity, and small thermo-optic coefficients make KTiOPO{sub 4} (KTP) an attractive material for use in a high average power Q-switch. However, electro-chromic damage and refractive index homogeneity have prevented the utilization of KTP in such a device in the past. This work shows that electro-chromic damage is effectively suppressed using capacitive coupling, and a KTP crystal can be Q-switched for 1.5 {times} 10{sup 9} shots without any detectable electro-chromic damage. In addition, KTP with the high uniformity and large aperture size needed for a KTP electro-optic Q-switch can be obtained from flux crystals grown at constant temperature. A thermally compensated, dual crystal KTP Q-switch, which successfully produced 50 mJ pulses with a pulse width of 8 ns (FWHM), has been constructed. In addition, in off-line testing the Q-switch showed less than 7% depolarization at an average power loading of 3.2 kW/cm{sup 2}.

  10. Femtosecond laser materials processing

    SciTech Connect

    Stuart, B. C., LLNL

    1998-06-02

    Femtosecond lasers enable materials processing of most any material with extremely high precision and negligible shock or thermal loading to the surrounding area Applications ranging from drilling teeth to cutting explosives to making high-aspect ratio cuts in metals with no heat-affected zone are made possible by this technology For material removal at reasonable rates, we developed a fully computer-controlled 15-Watt average power, 100-fs laser machining system.

  11. Ultrafast green laser exceeding 400 W of average power

    NASA Astrophysics Data System (ADS)

    Gronloh, Bastian; Russbueldt, Peter; Jungbluth, Bernd; Hoffmann, Hans-Dieter

    2014-05-01

    We present the world's first laser at 515 nm with sub-picosecond pulses and an average power of 445 W. To realize this beam source we utilize an Yb:YAG-based infrared laser consisting of a fiber MOPA system as a seed source, a rod-type pre-amplifier and two Innoslab power amplifier stages. The infrared system delivers up to 930 W of average power at repetition rates between 10 and 50 MHz and with pulse durations around 800 fs. The beam quality in the infrared is M2 = 1.1 and 1.5 in fast and slow axis. As a frequency doubler we chose a Type-I critically phase-matched Lithium Triborate (LBO) crystal in a single-pass configuration. To preserve the infrared beam quality and pulse duration, the conversion was carefully modeled using numerical calculations. These take dispersion-related and thermal effects into account, thus enabling us to provide precise predictions of the properties of the frequency-doubled beam. To be able to model the influence of thermal dephasing correctly and to choose appropriate crystals accordingly, we performed extensive absorption measurements of all crystals used for conversion experiments. These measurements provide the input data for the thermal FEM analysis and calculation. We used a Photothermal Commonpath Interferometer (PCI) to obtain space-resolved absorption data in the bulk and at the surfaces of the LBO crystals. The absorption was measured at 1030 nm as well as at 515 nm in order to take into account the different absorption behavior at both occurring wavelengths.

  12. Picosecond to femtosecond pulses from high power self mode-locked ytterbium rod-type fiber laser.

    PubMed

    Deslandes, Pierre; Perrin, Mathias; Saby, Julien; Sangla, Damien; Salin, François; Freysz, Eric

    2013-05-01

    We have designed an ytterbium rod-type fiber laser oscillator with tunable pulse duration. This system that delivers more than 10 W of average power is self mode-locked. It yields femtosecond to picosecond laser pulses at a repetition rate of 74 MHz. The pulse duration is adjusted by changing the spectral width of a band pass filter that is inserted in the laser cavity. Using volume Bragg gratings of 0.9 nm and 0.07 nm spectrum bandwidth, this oscillator delivers nearly Fourier limited 2.8 ps and 18.5 ps pulses, respectively. With a 4 nm interference filter, one obtains picosecond pulses that have been externally dechirped down to 130 fs. PMID:23669929

  13. High Average Power Nd:YAG Slab Laser

    NASA Astrophysics Data System (ADS)

    Kasai, Takeshi; Sindo, Yoshihiko; Haga, Keiji

    1989-07-01

    A slab geometry Nd:YAG laser with a zigzag optical path is described. The dimensions of the Nd:YAG slab are 5.6 x 18.4 x 153.9 mm, and Nei' ion concentration is 1.1 at.%. Two krypton flashlamps, one located on each side of the YAG slab, are used for pumping. The conditions for normal pulsed operation were as follows: the repetition rate was from 5 to 27 pps, and the pulse durations were 4 and 9.9 ms. With the above conditions, a maximum average output power of 500 W was obtained with an efficiency of 2 %, the slope efficiency being 2.4 %. The beam divergence was estimated to be 10x25 mrad. The stability of the laser output power was about +/-1.5 %. Another oscillator that includes intra-cavity cylindrical lenses, was also designed. Using this resonator configuration reduced the beam divergence to about 7.6 x8.2 mrad. The preliminary laser processing experiment was attemped using this laser oscillator.

  14. High-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power.

    PubMed

    Rudin, B; Wittwer, V J; Maas, D J H C; Hoffmann, M; Sieber, O D; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U

    2010-12-20

    High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (<200 mW). We have demonstrated the power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser. PMID:21197032

  15. High Average Power Lasers for the Photon Collider

    SciTech Connect

    Stuart, B; Gronberg, J; Seryi, A

    2009-04-29

    The idea to convert an electron collider into a high energy photon collider has existed for several decades. A key technological limitation to realizing this idea is the need to create a large amount of laser power to drive the Compton back-scattering. A concept to reduce the required laser power using a recirculating cavity has been proposed. We describe a concept for a laser architecture that could drive such a cavity.

  16. High average power magnetic modulator for metal vapor lasers

    DOEpatents

    Ball, Don G.; Birx, Daniel L.; Cook, Edward G.; Miller, John L.

    1994-01-01

    A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.

  17. Optimizing average power in low quantum defect lasers.

    PubMed

    Bowman, S R

    2015-11-01

    Waste heat generation is a generic problem in high-power solid-state laser systems. One way to reduce heat loading while improving efficiency is to reduce the laser's quantum defect. This paper presents a simple analysis of low quantum defect laser materials. In these laser materials, the effects of fluorescent cooling and weak loss processes should not be ignored. Simple expressions are developed for efficiency and heating in a steady-state purely radiative material. These expressions are then extended to include weak losses and fluorescence reabsorption. Evaluation of these relations using ytterbium-doped YAG is used to illustrate several optimization schemes and the impact of realistic losses. PMID:26560625

  18. Development of High Average Power Lasers for the Photon Collider

    SciTech Connect

    Gronberg, Jeff; Stuart, Brent; Seryi, Andrei; /SLAC

    2012-07-05

    The laser and optics system for the photon collider seeks to minimize the required laser power by using an optical stacking cavity to recirculate the laser light. An enhancement of between 300 to 400 is desired. In order to achieve this the laser pulses which drive the cavity must precisely match the phase of the pulse circulating within the cavity. We report on simulations of the performance of a stacking cavity to various variations of the drive laser in order to specify the required tolerances of the laser system.

  19. Borogermanate glasses for Faraday isolators at high average power

    NASA Astrophysics Data System (ADS)

    Starobor, A. V.; Zheleznov, D. S.; Palashov, O. V.; Savinkov, V. I.; Sigaev, V. N.

    2016-01-01

    The temperature dependence of Verdet constant and thermo-optical characteristics of a new magneto-optical borogermanate glass has been investigated. The performed analysis confirmed a possibility of developing a Faraday isolator and a cryogenic Faraday isolator based on the studied medium, providing a 25 dB isolation ratio of laser radiation in the "eye-safe" wavelength range (1530-1620 nm) at the power of 0.4 kW and 1.3 kW, respectively, which is a leading-edge result for magneto-optical glasses.

  20. Stand-off detection and classification of CBRNe using a Lidar system based on a high power femtosecond laser

    NASA Astrophysics Data System (ADS)

    Izawa, Jun; Yokozawa, Takeshi; Kurata, Takao; Yoshida, Akihiro; Mastunaga, Yasushi; Somekawa, Toshihiro; Eto, Shuzo; Manago, Naohiro; Horisawa, Hideyuki; Yamaguchi, Shigeru; Fujii, Takashi; Kuze, Hiroaki

    2014-10-01

    We propose a stand-off system that enables detection and classification of CBRNe (Chemical, Biological, Radioactive, Nuclear aerosol and explosive solids). The system is an integrated lidar using a high-power (terawatt) femtosecond laser. The detection and classification of various hazardous targets with stand-off distances from several hundred meters to a few kilometers are achieved by means of laser-induced breakdown spectroscopy (LIBS) and two-photon fluorescence (TPF) techniques. In this work, we report on the technical considerations on the system design of the present hybrid lidar system consisting of a nanosecond laser and a femtosecond laser. Also, we describe the current progress in our laboratory experiments that have demonstrated the stand-off detection and classification of various simulants. For the R and N detection scheme, cesium chloride aerosols have successfully been detected by LIBS using a high-power femtosecond laser. For the B detection scheme, TPF signals of organic aerosols such as riboflavin have clearly been recorded. In addition, a compact femtosecond laser has been employed for the LIBS classification of organic plastics employed as e-simulants.

  1. Energy stability in a high average power FEL

    SciTech Connect

    Mermings, L.; Bisognano, J.; Delayen, J.

    1995-12-31

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields or beam current are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Furthermore, the analytical model is extended to include feedback. Comparison with simulation results derived from direct integration of the equations of motion is presented. Design strategies to increase the instability threshold are discussed and the UV Demo FEL, proposed for construction at CEBAF, and the INP Recuperatron at Novosibirsk are used as examples.

  2. Development of High Average Power Lasers for the Photon Collider

    SciTech Connect

    Gronberg, J; Stuart, B; Seryi, A

    2010-05-17

    The laser and optics system for the photon collider seeks to minimize the required laser power by using an optical stacking cavity to recirculate the laser light. An enhancement of between 300 to 400 is desired. In order to achieve this the laser pulses which drive the cavity must precisely match the phase of the pulse circulating within the cavity. We report on simulations of the performance of a stacking cavity to various variations of the drive laser in order to specify the required tolerances of the laser system. We look at the behavior of a simple four mirror cavity as shown in Fig. 1. As a unit input pulse is applied to the coupling mirror a pulse begins to build up in the interior of the cavity. If the drive pulses and the interior pulse arrive at the coupling mirror in phase the interior pulse will build up to a larger value. The achievable enhancement is a strong function of the reflectivity of the cavities. The best performance if attained when the reflectivities of the input coupler is matched to the internal reflectivities of the cavity. In Fig. 2 we show the build up of the internal pulse after a certain number of drive pulses, assuming the input coupler has a reflectivity of 0.996 and the interior mirrors have 0.998 reflectivity. With these parameters the cavity will reach an enhancement factor of 450. Reducing the coupler reflectivity gives a faster cavity loading rate but with a reduced enhancement of the internal pulse. The enhancement as a function of coupler reflectivity and total internal cavity reflectivity is shown in Fig. 3. The best enhancement is achieved when the coupling mirror is matched to the reflectivity of the cavity. A coupler reflectivity just below the internal cavity reflectivity minimizes the required laser power.

  3. High average power lasers for future particle accelerators

    NASA Astrophysics Data System (ADS)

    Dawson, Jay W.; Crane, John K.; Messerly, Michael J.; Prantil, Matthew A.; Pax, Paul H.; Sridharan, Arun K.; Allen, Graham S.; Drachenberg, Derrek R.; Phan, Henry H.; Heebner, John E.; Ebbers, Christopher A.; Beach, Raymond J.; Hartouni, Edward P.; Siders, Craig W.; Spinka, Thomas M.; Barty, C. P. J.; Bayramian, Andrew J.; Haefner, Leon C.; Albert, Felicie; Lowdermilk, W. Howard; Rubenchik, Alexander M.; Bonanno, Regina E.

    2012-12-01

    Lasers are of increasing interest to the accelerator community and include applications as diverse as stripping electrons from hydrogen atoms, sources for Compton scattering, efficient high repetition rate lasers for dielectric laser acceleration, peta-watt peak power lasers for laser wake field and high energy, short pulse lasers for proton and ion beam therapy. The laser requirements for these applications are briefly surveyed. State of the art of laser technologies with the potential to eventually meet those requirements are reviewed. These technologies include diode pumped solid state lasers (including cryogenic), fiber lasers, OPCPA based lasers and Ti:Sapphire lasers. Strengths and weakness of the various technologies are discussed along with the most important issues to address to get from the current state of the art to the performance needed for the accelerator applications. Efficiency issues are considered in detail as in most cases the system efficiency is a valuable indicator of the actual ability of a given technology to deliver the application requirements.

  4. Low threshold power density for the generation of frequency up-converted pulses in bismuth glass by two crossing chirped femtosecond pulses.

    PubMed

    Zhang, Hang; Liu, Hui; Si, Jinhai; Yi, Wenhui; Chen, Feng; Hou, Xun

    2011-06-20

    We investigated the generation of frequency up-converted femtosecond laser pulses by nondegenerate cascaded four-wave mixing (CFWM) in a bismuth-oxide glass (BI glass). Broad-bandwidth light pulses with different propagation directions were simultaneously obtained by using two small-angle crossing femtosecond laser pulses in BI glass. Experimental results show that the threshold power density for the generation of broad-bandwidth femtosecond pulses in BI glass is one order of magnitude lower than that in fused silica. PMID:21716439

  5. Demonstration of a 10 kW average power 94 GHz gyroklystron amplifier

    NASA Astrophysics Data System (ADS)

    Blank, M.; Danly, B. G.; Levush, B.; Calame, J. P.; Nguyen, K.; Pershing, D.; Petillo, J.; Hargreaves, T. A.; True, R. B.; Theiss, A. J.; Good, G. R.; Felch, K.; James, B. G.; Borchard, P.; Cahalan, P.; Chu, T. S.; Jory, H.; Lawson, W. G.; Antonsen, T. M.

    1999-12-01

    The experimental demonstration of a high average power W-band (75-110 GHz) gyroklystron amplifier is reported. The gyroklystron has produced 118 AW peak output power and 29.5% electronic efficiency in the TE011 mode using a 66.7 kV, 6 A electron beam at 0.2% rf duty factor. At this operating point, the instantaneous full width at half-maximum (FWHM) bandwidth is 600 MHz. At 11% rf duty factor, the gyroklystron has produced up to 10.1 kW average power at 33% electronic efficiency with a 66 kV, 4.15 A electron beam. This represents world record performance for an amplifier at this frequency. At the 10.1 kW average power operating point, the FWHM bandwidth is 420 MHz. At higher magnetic fields and lower beam voltages, larger bandwidths can be achieved at the expense of peak and average output power.

  6. Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime

    SciTech Connect

    Carlin, P.W.

    1996-12-01

    Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases considered include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.

  7. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    SciTech Connect

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  8. High-power, femtosecond, thermal-lens-shaped Yb:KGW oscillator.

    PubMed

    Berger, Joel A; Greco, Michael J; Schroeder, W Andreas

    2008-06-01

    Thermal lens shaping for astigmatism compensation is extended to a high-power, diode-pumped, Yb:KGW laser by employing a gain crystal geometry designed for efficient polarized pumping. The 63MHz oscillator is soliton mode-locked with the aid of a saturable Bragg reflector to yield 250fs (347fs) pulses at an output power of 3.5W (5W). Frequency doubling of the 250fs pulses with an intrinsic efficiency >60% provides 1.65W of average green power. PMID:18545576

  9. High power mode-locked rod-type fiber femtosecond laser with micro-joule energy

    NASA Astrophysics Data System (ADS)

    Lv, Zhiguo; Teng, Hao; Wang, Lina; Wang, Rui; Wang, Junli; Wei, Zhiyi

    2016-07-01

    We report a high power all-normal-dispersion (ANDi) mode-locked laser based on nonlinear polarization evolution (NPE) technique using rod-type fiber with polarization maintaining (PM) characteristic. With 85 μm gain core diameter, 31 W of average power at repetition rates of 57.93 MHz, which corresponds to the pulse energy of 0.53 μJ, is demonstrated under a pump power of 93 W. The pulse duration of 124 fs after compressor is obtained at the central wavelength of 1033 nm as well as the measured power jitter of 0.3% over a period of 2 h. To our knowledge, this is the first realization of the highest power of ANDi fiber laser by pure NPE mode-locking technique based on fibers with PM characteristic as gain media.

  10. Estimation of average annual streamflows and power potentials for Alaska and Hawaii

    SciTech Connect

    Verdin, Kristine L.

    2004-05-01

    This paper describes the work done to develop average annual streamflow estimates and power potential for the states of Alaska and Hawaii. The Elevation Derivatives for National Applications (EDNA) database was used, along with climatic datasets, to develop flow and power estimates for every stream reach in the EDNA database. Estimates of average annual streamflows were derived using state-specific regression equations, which were functions of average annual precipitation, precipitation intensity, drainage area, and other elevation-derived parameters. Power potential was calculated through the use of the average annual streamflow and the hydraulic head of each reach, which is calculated from the EDNA digital elevation model. In all, estimates of streamflow and power potential were calculated for over 170,000 stream segments in the Alaskan and Hawaiian datasets.

  11. Technical options for high average power free electron milimeter-wave and laser devices

    NASA Technical Reports Server (NTRS)

    Swingle, James C.

    1989-01-01

    Many of the potential space power beaming applications require the generation of directed energy beams with respectable amounts of average power (MWs). A tutorial summary is provided here on recent advances in the laboratory aimed at producing direct conversion of electrical energy to electromagnetic radiation over a wide spectral regime from microwaves to the ultraviolet.

  12. Narrowband cw injection seeded high power femtosecond double-pass optical parametric generator at 43 MHz: Gain and noise dynamics.

    PubMed

    Linnenbank, Heiko; Steinle, Tobias; Giessen, Harald

    2016-08-22

    We demonstrate narrowband cw injection seeding of a femtosecond double-pass optical parametric generator at 43 MHz repetition rate with a simple, low power external cavity diode laser. Up to 2.5 W of near-IR radiation (1.5 - 1.66 µm) as well as 800 mW of tunable mid-IR radiation (2.75 - 3.15 µm) with pulse durations below 300 fs are generated with a remarkable pulse-to-pulse and long term power stability. Compared to conventional, vacuum noise seeded optical parametric generators, the presented frequency conversion scheme does not only exhibit superior gain and noise dynamics, but also a high degree of flexibility upon control parameters such as pump power, seed power, or spectral position of the seed. PMID:27557233

  13. Time Averaged Transmitter Power and Exposure to Electromagnetic Fields from Mobile Phone Base Stations

    PubMed Central

    Bürgi, Alfred; Scanferla, Damiano; Lehmann, Hugo

    2014-01-01

    Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor F ≈ 0.32 ± 0.08 for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels. PMID:25105551

  14. High-average-power operation of a pulsed Raman fiber amplifier at 1686 nm.

    PubMed

    Yao, Weichao; Chen, Bihui; Zhang, Jianing; Zhao, Yongguang; Chen, Hao; Shen, Deyuan

    2015-05-01

    We report on high-average-power operation of a pulsed Raman fiber amplifier at ~1686 nm which cannot be covered by rare-earth-doped fiber lasers. The Raman fiber amplifier was pumped by a home-made 1565.2 nm Q-switched Er,Yb fiber laser and worked at a repetition frequency of 184 kHz. With 0.8 km Raman fiber, 4.4 W of average output power at the 1st order Stokes wavelength of 1686.5 nm was obtained for launched pump power of 16.2 W, corresponding to an optical-to-optical conversion efficiency of 27.2%. Further increasing the pump power, high-order Stokes waves grew gradually, resulting in a total output power of 6.7 W at the 19.2 W launched pump power. PMID:25969195

  15. Performance and production requirements for the optical components in a high-average-power laser system

    SciTech Connect

    Chow, R.; Doss, F.W.; Taylor, J.R.; Wong, J.N.

    1999-07-02

    Optical components needed for high-average-power lasers, such as those developed for Atomic Vapor Laser Isotope Separation (AVLIS), require high levels of performance and reliability. Over the past two decades, optical component requirements for this purpose have been optimized and performance and reliability have been demonstrated. Many of the optical components that are exposed to the high power laser light affect the quality of the beam as it is transported through the system. The specifications for these optics are described including a few parameters not previously reported and some component manufacturing and testing experience. Key words: High-average-power laser, coating efficiency, absorption, optical components

  16. New transient absorption observed in the spectrum of colloidal CdSe nanoparticles pumped with high-power femtosecond pulses

    SciTech Connect

    Burda, C.; Link, S.; Green, T.C.; El-Sayed, M.A.

    1999-12-09

    The power dependence of the transient absorption spectrum of CdSe nanoparticle colloids with size distribution of 4.0 {+-} 0.4 nm diameter is studied with femtosecond pump-probe techniques. At the lowest pump laser power, the absorption bleaching (negative spectrum) characteristic of the exciton spectrum is observed with maxima at 560 and 480 nm. As the pump laser power increases, two new transient absorptions at 510 and 590 nm with unresolved fast rise (<100 fs) and long decay times ({much{underscore}gt}150 ps) are observed. The energy of each of the positive absorption is red shifted from that of the bleach bands by {approximately}120 MeV. The origin of this shift is discussed in terms of the effect of the internal electric field of the many electron-hole pairs formed within the quantum dot at the high pump intensity, absorption from a metastable excited state or the formation of biexcitons.

  17. Dynamic Power Management for Sensor Node in WSN Using Average Reward MDP

    NASA Astrophysics Data System (ADS)

    Kianpisheh, Somayeh; Charkari, Nasrolah Moghadam

    Reducing energy consumption is one of the key challenges in sensor networks. One technique to reduce energy consumption is dynamic power management. In this paper we model power management problem in a sensor node as an average reward Markov Decision Process and solve it using dynamic programming. We achieve an optimal policy that maximizes long-term average of utility per energy consumption. Simulation results show our approach has the ability of reaching to the same amount of utility as always on policy while consuming less energy than always on policy.

  18. High average power parametric frequency conversion-new concepts and new pump sources

    SciTech Connect

    Velsko, S.P.; Webb, M.S.

    1994-03-01

    A number of applications, including long range remote sensing and antisensor technology, require high average power tunable radiation in several distinct spectral regions. Of the many issues which determine the deployability of optical parametric oscillators (OPOS) and related systems, efficiency and simplicity are among the most important. It is only recently that the advent of compact diode laser pumped solid state lasers has produced pump sources for parametric oscillators which can make compact, efficient, high average power tunable sources possible. In this paper we outline several different issues in parametric oscillator and pump laser development which are currently under study at Lawrence Livermore National Laboratory.

  19. High-average-power 100-Hz repetition rate table-top soft x-ray lasers

    NASA Astrophysics Data System (ADS)

    Rocca, Jorge J.; Reagan, Brendan A.; Wernsing, Keith; Wang, Yong; Yin, Liang; Wang, Shoujun; Berrill, Mark; Woolston, Mark R.; Curtis, Alden H.; Furch, Federico J. A.; Shlyaptsev, Vyacheslav N.; Luther, Brad M.; Patel, Dinesh; Marconi, Mario C.; Menoni, Carmen S.

    2013-09-01

    The table-top generation of high average power coherent soft x-ray radiation in a compact set up is of high interest for numerous applications. We have demonstrated the generation of bright soft x-ray laser pulses at 100 Hz repetition rate with record-high average power from compact plasma amplifiers excited by an ultrafast diode-pumped solid state laser. Results of compact λ=18.9nm Ni-like Mo and λ=13.9nm Ni-like Ag lasers operating at 100 Hz repetition rate are discussed.

  20. Generation and parametric amplification of femtosecond radiation up to terawatt power in the mid-infrared

    NASA Astrophysics Data System (ADS)

    Trunov, V. I.; Frolov, S. A.; Pestryakov, E. V.

    2015-11-01

    Nonlinear optical schemes for generation of terawatt femtosecond pulses in the range of 2-10 μm using multiterawatt laser radiation of the two-channel system created in the ILP SB RAS are presented and discussed. It is shown that the use of large aperture LBO crystals and AgGaGeS4 for difference frequency generation and parametric amplification enables to generate a wideband radiation in the range of 2-10 μm.

  1. Average power scaling of UV excimer lasers drives flat panel display and lidar applications

    NASA Astrophysics Data System (ADS)

    Herbst, Ludolf; Delmdahl, Ralph F.; Paetzel, Rainer

    2012-03-01

    Average power scaling of 308nm excimer lasers has followed an evolutionary path over the last two decades driven by diverse industrial UV laser microprocessing markets. Recently, a new dual-oscillator and beam management concept for high-average power upscaling of excimer lasers has been realized, for the first time enabling as much as 1.2kW of stabilized UV-laser average output power at a UV wavelength of 308nm. The new dual-oscillator concept enables low temperature polysilicon (LTPS) fabrication to be extended to generation six glass substrates. This is essential in terms of a more economic high-volume manufacturing of flat panel displays for the soaring smartphone and tablet PC markets. Similarly, the cost-effective production of flexible displays is driven by 308nm excimer laser power scaling. Flexible displays have enormous commercial potential and can largely use the same production equipment as is used for rigid display manufacturing. Moreover, higher average output power of 308nm excimer lasers aids reducing measurement time and improving the signal-to-noise ratio in the worldwide network of high altitude Raman lidar stations. The availability of kW-class 308nm excimer lasers has the potential to take LIDAR backscattering signal strength and achievable altitude to new levels.

  2. Megawatt-scale average-power ultrashort pulses in an enhancement cavity.

    PubMed

    Carstens, H; Lilienfein, N; Holzberger, S; Jocher, C; Eidam, T; Limpert, J; Tünnermann, A; Weitenberg, J; Yost, D C; Alghamdi, A; Alahmed, Z; Azzeer, A; Apolonski, A; Fill, E; Krausz, F; Pupeza, I

    2014-05-01

    We investigate power scaling of ultrashort-pulse enhancement cavities. We propose a model for the sensitivity of a cavity design to thermal deformations of the mirrors due to the high circulating powers. Using this model and optimized cavity mirrors, we demonstrate 400 kW of average power with 250 fs pulses and 670 kW with 10 ps pulses at a central wavelength of 1040 nm and a repetition rate of 250 MHz. These results represent an average power improvement of one order of magnitude compared to state-of-the-art systems with similar pulse durations and will thus benefit numerous applications such as the further scaling of tabletop sources of hard x rays (via Thomson scattering of relativistic electrons) and of soft x rays (via high harmonic generation). PMID:24784054

  3. High average power quasi-CW single-mode green and UV fiber lasers

    NASA Astrophysics Data System (ADS)

    Avdokhin, Alexey; Gapontsev, Valentin; Kadwani, Pankaj; Vaupel, Andreas; Samartsev, Igor; Platonov, Nicholai; Yusim, Alex; Myasnikov, Daniil

    2015-02-01

    Kilowatt-level narrow-linewidth SM ytterbium fiber laser operating in high-repetition-rate QCW regime was used to obtain 700 W average power at 532 nm with single-mode beam quality and wall-plug efficiency of over 23 %. To the best of our knowledge, this is ~60 % higher power than previously reported for single-mode green lasers based on other platforms, and also is ~30 % increase comparing to the previous result obtained by our group on the base of similar fiber laser platform. We have also experimentally proved that the same type of fiber laser can be used for generating of world-record levels of power at other wavelengths of visible and UV spectral ranges by employing cascaded non-linear frequency conversion. Thus, utilizing frequency tripling in 2 LBO crystals, we achieved over 160 W average power of nearly single-mode UV light at 355 nm with THG efficiency of more than 25 %. As far as we know, this is the highest output power ever reported for UV laser with nearly diffraction limited beam quality. We also conducted some preliminary experiments to demonstrate suitability of our approach for generating longer wavelengths of the visible spectrum. By pre-shifting fundamental emission wavelength in fiber Raman converter, followed by frequency doubling in NCPM LBO, we obtained average powers of 36 W at 589 nm and 27 W at 615 nm. These proof-of-concept experiments were performed with low-power pump laser and were not fully optimized with respect to frequency conversion. Our analysis indicates that employing kW-level QCW ytterbium laser with optimized SRS and SHG converters we can achieve hundreds of Watts of average power in red and orange color with single-mode beam quality.

  4. Optical design and performance of the amplifier stage for the average power laser experiment

    NASA Astrophysics Data System (ADS)

    Quimby, D. C.; Parazzoli, C. G.; Pistoresi, D. J.

    1992-07-01

    Boeing, in collaboration with Los Alamos and STI Optronics, is embarking on a program to build and operate the Average Power Laser Experiment (APLE) to demonstrate the high power capability of free-electron lasers at a wavelength of 10 μm. The experiment utilizes the single-accelerator, master-oscillator, power-amplifier (SAMOPA) approach. The performance of the power amplifier stage, as calculated by the time-dependent 3D FELEX code, is presented. The SAMOPA concept has important advantages in terms of excellent electron trapping fraction and remarkable insensitivity to slippage, input optical power, and detuning from resonance, but key requirements are placed on the e-beam peak current and emittance and on the allowable induced energy spread in the oscillator stage. Optical design tradeoffs between strong guiding and power extraction are described and a complete evaluation of the performance sensitivity to various error sources and misalignments is presented.

  5. Cryogenic Yb:YAG picosecond laser with high average power visible and ultraviolet harmonic generation

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Kowalewski, K.; Envid, V.; Zembek, J.; Canale, B.; Kolis, J. W.; McMillen, C. D.; Geisber, H.

    2012-06-01

    Cryogenic Yb:YAG lasers operating at 1029 nm have been demonstrated at Snake Creek Lasers with high average power CW and ultrafast output powers, and provide near diffraction-limited output beams that are ideal for applications in harmonic generation. We describe experiments that have produced high average power green output power at 515 nm as well as preliminary experiments producing UV output power at 257.25 nm. Frequency doubling experiments used a 20 mm long non-critically phase-matched LBO crystal mounted in a constant temperature oven. A mode-locked Yb fiber laser operating at 50 MHz was used to drive a two Yb:YAG cryogenic amplifier system, producing hundreds of watts of average power output with a FWHM pulsewidth of 12 ps. Doubling efficiencies of > 50 % have been observed. For frequency quadrupling, we have used hydrothermally grown KTTP crystals grown at Clemson University and Advanced Photonic Crystals. KBBF offers unprecedented UV transmission down to 155 nm, and was used in a Type I phasematching configuration. The properties of KBBF will be discussed, as well as the experimental results observed and conversion efficiency.

  6. High Average Power Operation of a Scraper-Outcoupled Free-Electron Laser

    SciTech Connect

    Michelle D. Shinn; Chris Behre; Stephen Vincent Benson; Michael Bevins; Don Bullard; James Coleman; L. Dillon-Townes; Tom Elliott; Joe Gubeli; David Hardy; Kevin Jordan; Ronald Lassiter; George Neil; Shukui Zhang

    2004-08-01

    We describe the design, construction, and operation of a high average power free-electron laser using scraper outcoupling. Using the FEL in this all-reflective configuration, we achieved approximately 2 kW of stable output at 10 um. Measurements of gain, loss, and output mode will be compared with our models.

  7. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina.

    PubMed

    Alexander, Nathan S; Palczewska, Grazyna; Stremplewski, Patrycjusz; Wojtkowski, Maciej; Kern, Timothy S; Palczewski, Krzysztof

    2016-07-01

    Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [Palczewska G., Nat Med.20, 785 (2014) Sharma R., Biomed. Opt. Express4, 1285 (2013)]. PMID:27446697

  8. GENERATION OF HIGH-AVERAGE-POWER ULTRABROAD-BAND INFRARED PULSES

    EPA Science Inventory

    This paper summarizes the results of analytical and numerical studies on a novel technique that is capable of providing high average power ultra broadband radiation that extends from approximately 2 to 16 m. Such a spectrum has several potential applications, including telecommu...

  9. Development of a high average power, CW, MM-wave FEL

    SciTech Connect

    Ramian, G.

    1995-12-31

    Important operational attributes of FELs remain to be demonstrated including high average power and single-frequency, extremely narrow-linewidth lasing. An FEL specifically designed to achieve these goals for scientific research applications is currently under construction. Its most salient feature is operation in a continuous-wave (CW) mode with an electrostatically generated, high-current, recirculating, DC electron beam.

  10. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina

    PubMed Central

    Alexander, Nathan S.; Palczewska, Grazyna; Stremplewski, Patrycjusz; Wojtkowski, Maciej; Kern, Timothy S.; Palczewski, Krzysztof

    2016-01-01

    Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [PalczewskaG., Nat Med. 20, 785 (2014)24952647 SharmaR., Biomed. Opt. Express 4, 1285 (2013)24009992]. PMID:27446697

  11. Gain measurements and average power capabilities of Cr(3+): LiSrAlF6

    NASA Astrophysics Data System (ADS)

    Hanson, F.; Bendall, C.; Poirier, P.

    1993-09-01

    Long wavelength operation of Cr:LiSrAlF6 is reported. The problem of thermal fracture effectively limits flash-lamp-pumped rod geometries to lower repetition rates. Thin face-pumped slabs allow higher average power capability, but peak gain could be limited by upconversion losses.

  12. Bessel integrals in epsilon expansion: Squared spherical Bessel functions averaged with Gaussian power-law distributions

    NASA Astrophysics Data System (ADS)

    Tomaschitz, Roman

    2013-12-01

    Bessel integrals of type {int_0^infty {k^{μ+2}{e}^{-ak2-(b+{i} ω)k}j_l^{2} (pk)dk}} are studied, where the squared spherical Bessel function j {/l 2} is averaged with a modulated Gaussian power-law density. These integrals define the multipole moments of Gaussian random fields on the unit sphere, arising in multipole fits of temperature and polarization power spectra of the cosmic microwave background. The averages can be calculated in closed form as finite Hankel series, which allow high-precision evaluation. In the case of integer power-law exponents μ, singularities emerge in the series coefficients, which requires ɛ expansion. The pole extraction and regularization of singular Hankel series is performed, for integer Gaussian power-law densities as well as for the special case of Kummer averages (a = 0 in the exponential of the integrand). The singular ɛ residuals are used to derive combinatorial identities (sum rules) for the rational Hankel coefficients, which serve as consistency checks in precision calculations of the integrals. Numerical examples are given, and the Hankel evaluation of Gaussian and Kummer averages is compared with their high-index Airy approximation over a wide range of integer Bessel indices l.

  13. The LUCIA project: a high average power ytterbium diode pumped solid state laser chain

    NASA Astrophysics Data System (ADS)

    Bourdet, Gilbert L.; Chanteloup, Jean-Christophe; Fulop, A.; Julien, Y.; Migus, Arnold

    2004-04-01

    With the goal to set up a high average power Diode Pumped Solid State Laser (100 Joules/10 Hz/10 ns), the Laboratory for Use of Intense Laser (LULI) is now studying various solutions concerning the amplifier medium, the cooling, the pumping and the extraction architectures. In this paper, we present the last states of these developments and the solutions already chosen.

  14. Estimating ensemble average power delivered by a piezoelectric patch actuator to a non-deterministic subsystem

    NASA Astrophysics Data System (ADS)

    Muthalif, Asan G. A.; Wahid, Azni N.; Nor, Khairul A. M.

    2014-02-01

    Engineering systems such as aircraft, ships and automotive are considered built-up structures. Dynamically they are taught of as being fabricated from many components that are classified as 'deterministic subsystems' (DS) and 'non-deterministic subsystems' (Non-DS). Structures' response of the DS is deterministic in nature and analysed using deterministic modelling methods such as finite element (FE) method. The response of Non-DS is statistical in nature and estimated using statistical modelling technique such as statistical energy analysis (SEA). SEA method uses power balance equation, in which any external input to the subsystem must be represented in terms of power. Often, input force is taken as point force and ensemble average power delivered by point force is already well-established. However, the external input can also be applied in the form of moments exerted by a piezoelectric (PZT) patch actuator. In order to be able to apply SEA method for input moments, a mathematical representation for moment generated by PZT patch in the form of average power is needed, which is attempted in this paper. A simply-supported plate with attached PZT patch is taken as a benchmark model. Analytical solution to estimate average power is derived using mobility approach. Ensemble average of power given by the PZT patch actuator to the benchmark model when subjected to structural uncertainties is also simulated using Lagrangian method and FEA software. The analytical estimation is compared with the Lagrangian model and FE method for validation. The effects of size and location of the PZT actuators on the power delivered to the plate are later investigated.

  15. High average power of Q-switched Tm:YAG slab laser

    NASA Astrophysics Data System (ADS)

    Jin, Lin; Liu, Pian; Liu, Xuan; Huang, Haitao; Yao, Weichao; Shen, Deyuan

    2016-08-01

    A laser-diode end-pumped Tm:YAG single crystal slab laser in acousto-optic Q-switched operation was demonstrated. For Q-switched operation, the average output power of 20.7 W at 1 kHz was achieved under the absorbed pump power of 83.6 W, corresponding to the slope efficiency of 36.1%, the shortest pulse width of 84 ns and the maximum pulse energy of 20.7 mJ with peak power of 250 kW were obtained.

  16. Recent advances in the development of high average power induction accelerators for industrial and environmental applications

    SciTech Connect

    Neau, E.L.

    1994-09-01

    Short-pulse accelerator technology developed during the early 1960`s through the late 1980`s is being extended to high average power systems capable of use in industrial and environmental applications. Processes requiring high dose levels and/or high volume throughput will require systems with beam power levels from several hundreds of kilowatts to megawatts. Beam accelerating potentials can range from less than 1 MeV to as much as 10 MeV depending on the type of beam, depth of penetration required, and the density of the product being treated. This paper addresses the present status of a family of high average power systems, with output beam power levels up to 200 kW, now in operation that use saturable core switches to achieve output pulse widths of 50 to 80 nanoseconds. Inductive adders and field emission cathodes are used to generate beams of electrons or x-rays at up to 2.5 MeV over areas of 1000 cm{sup 2}. Similar high average power technology is being used at {le} 1 MeV to drive repetitive ion beam sources for treatment of material surfaces over 100`s of cm{sup 2}.

  17. High average power picosecond pulse generation from a thulium-doped all-fiber MOPA system.

    PubMed

    Liu, Jiang; Wang, Qian; Wang, Pu

    2012-09-24

    We report a stable highly-integrated high power picosecond thulium-doped all-fiber MOPA system without using conventional chirped pulse amplification technique. The master oscillator was passively mode-locked by a SESAM to generate average power of 15 mW at a fundamental repetition rate of 103 MHz in a short linear cavity, and a uniform narrow bandwidth FBG is employed to stabilize the passively mode-locked laser operation. Two-stage double-clad thulium-doped all-fiber amplifiers were used directly to boost average power to 20.7 W. The laser center wavelength was 1962.8 nm and the pulse width was 18 ps. The single pulse energy and peak-power after the amplication were 200 nJ and 11.2 kW respectively. To the best of our knowledge, this is the highest average power ever reported for a picosecond thulium-doped all-fiber MOPA system. PMID:23037392

  18. Non-chain pulsed DF laser with an average power of the order of 100 W

    NASA Astrophysics Data System (ADS)

    Pan, Qikun; Xie, Jijiang; Wang, Chunrui; Shao, Chunlei; Shao, Mingzhen; Chen, Fei; Guo, Jin

    2016-07-01

    The design and performance of a closed-cycle repetitively pulsed DF laser are described. The Fitch circuit and thyratron switch are introduced to realize self-sustained volume discharge in SF6-D2 mixtures. The influences of gas parameters and charging voltage on output characteristics of non-chain pulsed DF laser are experimentally investigated. In order to improve the laser power stability over a long period of working time, zeolites with different apertures are used to scrub out the de-excitation particles produced in electric discharge. An average output power of the order of 100 W was obtained at an operating repetition rate of 50 Hz, with amplitude difference in laser pulses <8 %. And under the action of micropore alkaline zeolites, the average power fell by 20 % after the laser continuing working 100 s at repetition frequency of 50 Hz.

  19. Electron-beam and high speed optical diagnostics for the Average Power Laser Experiment (APLE) program

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; McVey, B. D.; Greegor, R. B.; Dowell, D. H.

    The Average Power Laser Experiment (APLE) program is a collaboration of Boeing and Los Alamos to build a free-electron laser (FEL) operating at a wavelength of 10 microns and an average power of 100 kW. This program includes demonstration experiments at Boeing on the injector and at Los Alamos on a single accelerator master oscillator power amplifier (SAMOPA). In response to the simulations of the expected electron beam properties, diagnostic plans have been developed for the low-duty and the 25 percent-duty operations of APLE. Preliminary evaluations of diagnostics based on information conversion to visible or near infrared light (optical transition radiation, Cerenkov radiation, synchrotron radiation, and spontaneous emission radiation) or electrical signals (striplines, toroids, flying wires, etc.) are addressed.

  20. Measurement of the absorption of nonlinear crystals used for high-average-power frequency doubling

    NASA Astrophysics Data System (ADS)

    Mann, Guido; Seidel, Stefan

    1997-07-01

    The absorption coefficients of nonlinear crystals for fundamental and second harmonic wave are of great importance for high average power second harmonic generation. A practical method to measure low absorption coefficients for high average power second harmonic generation. A practical method to measure low absorption coefficients is to use an interferometric laser calorimeter with high power lasers. Therefore Q-switched Nd:YAG laser systems with intracavity second harmonic generation are used. The measurements are made with optical powers up to 300 W and 45 W, respectively. Because of the high power, the resolution limit for the absorption coefficients is 0.001 percent/cm. The absorption coefficients of KTP and LBO crystals of different manufacturers are determined. The results are used for a numerical model which takes into account the decrease of conversion efficiency due to thermal effects caused by the absorption of laser power in the nonlinear crystal. This model describes saturation effects which appear in the range of 100 W in the green using a KTP crystal. A new idea for compensation of thermal effects will be presented.

  1. High-average-power actively-mode-locked Tm3+ fiber lasers

    NASA Astrophysics Data System (ADS)

    Eckerle, Michael; Kieleck, Christelle; Hübner, Philipp; Świderski, Jacek; Jackson, Stuart D.; Mazé, Gwenael; Eichhorn, Marc

    2012-02-01

    Fiber lasers emitting in the 2 μm wavelength range doped with thulium ions can be used as highly efficient pump sources for nonlinear converters to generate mid-infrared radiation. For spectroscopic purposes, illumination and countermeasures, a broad mid-infrared emission spectrum is advantageous. This can be reached by supercontinuum generation in fibers, e.g. fluoride fibers, which up to now has, however, only been presented with either low average power, complex Raman-shifted 1.55 μm pump sources or multi-stage amplifier pump schemes. Here we present recent results of a new actively-mode-locked single-oscillator scheme that can provide the high-repetition rate sub-ns pump pulses needed for pumping supercontinuum generators. A thulium-doped silica fiber laser is presented that provides > 11 W of average power CW-mode-locked pulses at 38 MHz repetition rate at ~ 38 ps pulse width. Upgrading the setup to allow Q-switched mode-locked operation yields mode-locked 40 MHz pulses arranged in 60 kHz bunched Q-switch envelopes and thus increases further the available peak power. In this Q-switched mode-locked regime over 5 W of average power has been achieved.

  2. A kilowatt average power laser for sub-picosecond materials processing

    SciTech Connect

    Stephen V. Benson; George R. Neil; C. Bohn; , G. Biallas; D. Douglas; F. Dylla; J. Fugitt; K. Jordan; G. Krafft; , L. Merminga; , J. Preble; , Michelle D. Shinn; T. Siggins; R. Walker; B. Yunn

    1999-11-01

    The performance of laser pulses in the sub-picosecond range for materials processing is substantially enhanced over similar fluences delivered in longer pulses. Recent advances in the development of solid state lasers have progressed significantly toward the higher average powers potentially useful for many applications. Nonetheless, prospects remain distant for multi-kilowatt sub-picosecond solid state systems such as would be required for industrial scale surface processing of metals and polymers. The authors present operational results from the world's first kilowatt scale ultra-fast materials processing laser. A Free Electron Laser (FEL) called the IR Demo is operational as a User Facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. In its initial operation at high average power it is capable of wavelengths in the 2 to 6 micron range and can produce {approximately}0.7 ps pulses in a continuous train at {approximately}75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades in the near future will extend operation beyond 10 kW CW average power in the near IR and kilowatt levels of power at wavelengths from 0.3 to 60 microns. This paper will cover the design and performance of this groundbreaking laser and operational aspects of the User Facility.

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

    PubMed

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

    2012-02-27

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

  4. High-power, high-repetition-rate femtosecond pulses tunable in the visible.

    PubMed

    Ellingson, R J; Tang, C L

    1993-03-15

    We demonstrate a Ti:sapphire-pumped intracavity-doubled optical parametric oscillator (OPO) that generates a total of up to 240 mW of sub-100-fs pulses tunable in the visible. The OPO consists of a 1.5-mm-thick KTiPO(4) (KTP) crystal configured in a ring cavity that is synchronously pumped by a self-mode-locked Ti:sapphire laser operating at an 81-MHz repetition rate and 2.1-W average power, producing 115-fs pulses at lambda = 790 nm. Intracavity doubling of the OPO is accomplished by inserting a 47-microm-thick beta-BaB(2)O(4) crystal into an additional focus in the OPO cavity. We demonstrate continuous tuning of the second-harmonic output from 580 to 657 nm. The potential tuning range of this intracavity-doubled KTP OPO is approximately 500 to 800 nm. PMID:19802161

  5. High power multi-color OPCPA source with simultaneous femtosecond deep-UV to mid-IR outputs.

    PubMed

    Baudisch, M; Wolter, B; Pullen, M; Hemmer, M; Biegert, J

    2016-08-01

    Many experimental investigations demand synchronized pulses at various wavelengths, ideally with very short pulse duration and high repetition rate. Here we describe a femtosecond multi-color optical parametric chirped pulse amplifier (OPCPA) with simultaneous outputs from the deep-UV to the mid-IR with optical synchronization. The high repetition rate of 160 kHz is well suited to compensate for low interaction probability or low cross section in strong-field interactions. Our source features high peak powers in the tens to hundreds of MW regime with pulse durations below 110 fs, which is ideal for pump-probe experiments of nonlinear and strong-field physics. We demonstrate its utility by strong-field ionization experiments of xenon in the near- to mid-IR. PMID:27472624

  6. High-average-power water window soft X-rays from an Ar laser plasma

    NASA Astrophysics Data System (ADS)

    Amano, Sho

    2016-07-01

    A high average power of 140 mW and high conversion efficiency of 14% were demonstrated in “water window” soft X-rays generated using a laser plasma source developed in-house, when a solid Ar target was irradiated by a commercial Nd:YAG Q-switched laser with an energy of 1 J at a repetition rate of 1 Hz. This soft X-ray power compared favorably with that produced using a synchrotron radiation source, and the developed laser plasma source can be used in various applications, such as soft X-ray microscopy, in place of synchrotron facilities.

  7. Composite Thin-Disk Laser Scaleable to 100 kW Average Power Output and Beyond

    SciTech Connect

    Zapata, L.; Beach, R.; Payne, S.

    2000-06-01

    By combining newly developed technologies to engineer composite laser components with state of the art diode laser pump delivery technologies, we are in a position to demonstrate high beam quality, continuous wave, laser radiation at scaleable high average powers. The crucial issues of our composite thin disk laser technology were demonstrated during a successful first light effort. The high continuous wave power levels that are now within reach make this system of high interest to future DoD initiatives in solid-state laser technology for the laser weapon arena.

  8. Synchronously pumped optical parametric oscillation in periodically poled lithium niobate with 1-w average output power.

    PubMed

    Graf, T; McConnell, G; Ferguson, A I; Bente, E; Burns, D; Dawson, M D

    1999-05-20

    We report on a rugged all-solid-state laser source of near-IR radiation in the range of 1461-1601 nm based on a high-power Nd:YVO(4) laser that is mode locked by a semiconductor saturable Bragg reflector as the pump source of a synchronously pumped optical parametric oscillator with a periodically poled lithium niobate crystal. The system produces 34-ps pulses with a high repetition rate of 235 MHz and an average output power of 1 W. The relatively long pulses lead to wide cavity detuning tolerances. The comparatively narrow spectral bandwidth of <15 GHz is suitable for applications such as pollutant detection. PMID:18319928

  9. Synchronously injected amplifiers, a novel approach to high-average-power FEL

    SciTech Connect

    Nguyen, D.C.; Fortgang, C.M.; Goldstein, J.C.; Kinross-Wright, J.M.; Sheffield, R.L.

    1996-11-01

    Two new FEL ideas based on synchronously injected amplifiers are described. Both of these rely on the synchronous injection of the optical signal into a high-gain, high-efficiency tapered wiggler. The first concept, called Regenerative Amplifier FEL (RAFEL), uses an optical feedback loop to provide a coherent signal at the wiggler entrance so that the optical power can reach saturation rapidly. The second idea requires the use of a uniform wiggler in the feedback loop to generate light that can be synchronously injected back into the first wiggler. The compact Advanced FEL is being modified to implement the RAFEL concept. We describe future operation of the Advanced FEL at high average current and discuss the possibility of generating 1 kW average power.

  10. A high-average-power blue-green laser for underwater communications

    NASA Astrophysics Data System (ADS)

    Pacheco, D. P.; Aldag, H. R.; Klimek, D. E.; Rostler, P. S.; Scheps, R.

    A flashlamp-pumped dye laser designed for high average power at an atomic resonance line and long service life is described. Initial characterization yields broad output in excess of 4 J/pulse and tuned output greater than 1.5 J/pulse at 458 nm and 30 mA bandwidth. The laser design features are described, including the laser head, resonator, lamp driving circuitry, dye replenishment, and system component limiting service life.

  11. High-average-power narrow-line-width sum frequency generation 589 nm laser

    NASA Astrophysics Data System (ADS)

    Lu, Yanhua; Fan, Guobin; Ren, Huaijin; Zhang, Lei; Xu, Xiafei; Zhang, Wei; Wan, Min

    2015-10-01

    An 81 W average-power all-solid-state sodium beacon laser at 589 nm with a repetition rate of 250 Hz is introduced, which is based on a novel sum frequency generation idea between two high-energy, different line widths, different beam quality infrared lasers (a 1064 nm laser and a 1319 nm laser). The 1064 nm laser, which features an external modulated CW single frequency seed source and two stages of amplifiers, can provide average-power of 150 W, beam quality M2 of ~1.8 with ultra-narrow line width (< 100 kHz). The 1319 nm laser can deliver average-power of 100 W, beam quality M2 of ~3.0 with a narrow line width of ~0.3 GHz. By sum frequency mixing in a LBO slab crystal (3 mm x 12 mm x 50 mm), pulse energy of 325 mJ is achieved at 589 nm with a conversion efficiency of 32.5 %. Tuning the center wavelength of 1064 nm laser by a PZT PID controller, the target beam's central wavelength is accurately locked to 589.15910 nm with a line width of ~0.3 GHz, which is dominated mainly by the 1319 nm laser. The beam quality is measured to be M2 < 1.3. The pulse duration is measured to be 150 μs in full-width. To the best of our knowledge, this represents the highest average-power for all-solid-state sodium beacon laser ever reported.

  12. Use of induction linacs with nonlinear magnetic drive as high average power accelerators

    SciTech Connect

    Birx, D.L.; Cook, E.G.; Hawkins, S.A.; Newton, M.A.; Poor, S.E.; Reginato, L.L.; Schmidt, J.A.; Smith, M.W.

    1984-08-20

    The marriage of induction linac technology with Nonlinear Magnetic Modulators has produced some unique capabilities. It appears possible to produce electron beams with average currents measured in amperes, at gradients exceeding 1 Mev/meter, and with power efficiencies approaching 50%. A 2 MeV, 5 kA electron accelerator is under construction at Lawrence Livermore National Laboratory (LLNL) to allow us to demonstrate some of these concepts. Progress on this project is reported here.

  13. Average power constraints in AlGaAs semiconductor lasers under pulse-position-modulation conditions

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1986-01-01

    In some optical communications systems there are advantages to using low duty-cycle pulsed modulation formats such as pulse-position-modulation. However, because of intrinsic limitations of AlGaAs semiconductor lasers, the average power that they can deliver in a pulsed mode of operation is lower than in a CW mode. The magnitude of this problem and its implications are analyzed in this letter, and one possible solution is mentioned.

  14. Physical optics and the direction of maximization of the far-field average power

    NASA Astrophysics Data System (ADS)

    Asvestas, John S.

    1986-12-01

    For the problem of physical optics scattering by a perfectly conducting plate of finite dimensions and arbitrary shape, attention is drawn to the fact that the directions in which the far-field average power is maximized can be easily determined for H-polarization, while the same is not true for E-polarization. Moreover, it is shown by means of an example that the directions of maximization for E-polarization are not necessarily those for H-polarization.

  15. Temperature-insensitive frequency tripling for generating high-average power UV lasers.

    PubMed

    Zhong, Haizhe; Yuan, Peng; Wen, Shuangchun; Qian, Liejia

    2014-02-24

    Aimed for generating high-average power ultraviolet (UV) lasers via third-harmonic generation (THG) consisting of frequency doubling and tripling stages, we numerically and experimentally demonstrate a novel frequency tripling scheme capable of supporting temperature-insensitive phase-matching (PM). Two cascaded tripling crystals, with opposite signs of the temperature derivation of phase-mismatch, are proposed and theoretically studied for improving the temperature-acceptance of PM. The proof-of-principle tripling experiment using two crystals of LBO and BBO shows that the temperature acceptance can be ~1.5 times larger than that of using a single tripling crystal. In addition, the phase shift caused by air dispersion, along with its influence on the temperature-insensitive PM, are also discussed. To illustrate the potential applications of proposed two-crystal tripling design in the high-average-power regime, full numerical simulations for the tripling process, are implemented based on the realistic crystals. The demonstrated two-crystal tripling scheme may provide a promising route to high-average-power THG in the UV region. PMID:24663750

  16. High-index asymptotics of spherical Bessel products averaged with modulated Gaussian power laws

    NASA Astrophysics Data System (ADS)

    Tomaschitz, Roman

    2014-12-01

    Bessel integrals of type are investigated, where the kernel g( k) is a modulated Gaussian power-law distribution , and the jl ( m) are multiple derivatives of spherical Bessel functions. These integrals define the multipole moments of Gaussian random fields on the unit sphere, arising in multipole fits of temperature and polarization power spectra of the cosmic microwave background. Two methods allowing efficient numerical calculation of these integrals are presented, covering Bessel indices l in the currently accessible multipole range 0 ≤ l ≤ 104 and beyond. The first method is based on a representation of spherical Bessel functions by Lommel polynomials. Gaussian power-law averages can then be calculated in closed form as finite Hankel series of parabolic cylinder functions, which allow high-precision evaluation. The second method is asymptotic, covering the high- l regime, and is applicable to general distribution functions g( k) in the integrand; it is based on the uniform Nicholson approximation of the Bessel derivatives in conjunction with an integral representation of squared Airy functions. A numerical comparison of these two methods is performed, employing Gaussian power laws and Kummer distributions to average the Bessel products.

  17. Metal micro drilling combining high power femtosecond laser and trepanning head

    NASA Astrophysics Data System (ADS)

    Kling, R.; Dijoux, M.; Romoli, L.; Tantussi, F.; Sanabria, J.; Mottay, E.

    2013-03-01

    Trepanning heads are well known to be efficient in high aspect drilling and to provide a precise control of the hole geometry. Secondly, femtosecond lasers enable to minimize the heat effects and the recast layer on sidewalls but are typically used on thin sheet. The combination of both present a high potential for industrial applications such as injector or cooling holes where the bore sidewall topology has a major influence on the dynamics of the gas flow. In this paper we present results using this combination. The effect of pulse energy, repetition rate and revolution speed of the head on both geometry and roughness are discussed. The quality of the sidewall is checked by roughness measurement and by metallographic analysis (SEM; chemical etching, micro hardness).

  18. Free space optical communications systems using Mid-IR quantum cascade and low-power femtosecond laser source

    NASA Astrophysics Data System (ADS)

    Corrigan, Paul

    Free Space Optical (FSO) communication is a line of sight telecom technology delivering low-cost, high-volume bandwidth through the air (˜$20,000/1 day/Gbps). It is an appealing solution to the "Last-Mile" bottleneck in metropolitan areas where fiber optic deployment can be prohibitive. Over the past decade commercial design has incorporated traditional telecom components without reviewing the optimal physical layer. We therefore present a systematic investigation of physical light propagation for different laser wavelengths, investigating loss processes, margins and inherent security features. FSO's "Achilles Heel" is adverse weather which attenuates currently promoted continuous wave Near-IR systems (CW-1.55-mum). In certain conditions link range may be reduced to 50m. Absorption and Mie-scattering of light are the major obstacles for clear transmission. As scattering efficiency is coupled to the particle size to wavelength ratio, micron sized fog particles are the worst attenuators. Moving off the commercial basis we present two transmission and scattering studies demonstrating and explaining enhanced link performance for a longer wavelength Mid-IR (8.1-mum) vs. CW system and for low-power femtosecond pulse vs. CW system. We present data from the world's longest outdoor, collinear, multi-wavelength, FSO link and demonstrate that at its peak Mid-IR light attenuates 300% less power or equivalently has 3x deployable range potential. Our real-world result shows the empirical benchmark "Kruse-Mie Relation" which to date has discouraged Mid-IR industrial advancement incorrectly predicts a decrease in transmission for Mid-IR by up to 220%. We also present results for an indoor fog chamber experiment with artificial fog recording even stronger Mid-IR gains (+2000% power delivery). An indoor scattering measurement demonstrates Mid-IR light scatters 10x less power, accounting for the tremendous transmission gains and also demonstrating Mid-IR's inherent security

  19. 100 Hz repetition rate, high average power, plasma-based soft x-ray lasers

    NASA Astrophysics Data System (ADS)

    Reagan, Brendan; Wernsing, Keith; Baumgarten, Cory; Berrill, Mark; Durivage, Leon; Furch, Federico; Curtis, Alden; Luther, Bradley; Patel, Dinesh; Menoni, Carmen; Shlyaptsev, Vyacheslav; Rocca, Jorge

    2013-10-01

    Numerous applications demand high average power / high repetition rate compact sources of coherent soft x-ray radiation. We report the demonstration table-top soft x-ray lasers at wavelengths ranging from 10.9 nm to 18.9 nm from plasmas created at 100 Hz repetition rate. Results includes a record average power of 0.15 mW at λ = 18.9 nm from a laser-produced Mo plasma and 0.1 mW average power at λ = 13.9 nm from a Ag plasma. These soft x-ray lasers are driven by collisional electron impact excitation in elongated line focus plasmas a few mm in length heated by a compact, directly diode-pumped, chirped pulse amplification Yb:YAG laser that produces 1 J pulses of ps duration at 100 Hz repetition rate. Pulses from this laser irradiate the surface of polished metal targets producing transient population inversions on the 4d1S0 --> 4p1P1 transition of Ni-like ions. Tailoring of the temporal profile of the driver laser pulse is observed to significantly increase soft x-ray laser output power as well as allow the generation of shorter wavelength lasers with reduced pump energy. Work was supported by the NSF ERC for Extreme Ultraviolet Science and Technology using equipment developed under NSF Award MRI-ARRA 09-561, and by the AMOS program of the Office of Basic Energy Sciences, US Department of Energy.

  20. Application of Bayesian model averaging to measurements of the primordial power spectrum

    SciTech Connect

    Parkinson, David; Liddle, Andrew R.

    2010-11-15

    Cosmological parameter uncertainties are often stated assuming a particular model, neglecting the model uncertainty, even when Bayesian model selection is unable to identify a conclusive best model. Bayesian model averaging is a method for assessing parameter uncertainties in situations where there is also uncertainty in the underlying model. We apply model averaging to the estimation of the parameters associated with the primordial power spectra of curvature and tensor perturbations. We use CosmoNest and MultiNest to compute the model evidences and posteriors, using cosmic microwave data from WMAP, ACBAR, BOOMERanG, and CBI, plus large-scale structure data from the SDSS DR7. We find that the model-averaged 95% credible interval for the spectral index using all of the data is 0.940averaging can tighten the credible upper limit, depending on prior assumptions.

  1. High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner

    NASA Astrophysics Data System (ADS)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-03-01

    In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

  2. Experimental studies of high average power CO2-laser-induced thermomechanical processes

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, Manfred

    1990-04-01

    Pulsed high average power CO2 lasers allow for a most efficient conversion of coherence IR laser radiation into thermal and mechanical energies. Investigations using a specially developed repetitively pulsed high energy CO2 laser are presented. This powerful device provides mean powers of several kW and peak powers of the individual pulses in the multi-MW range. Studies were performed to obtain information on the transient behavior of the fast energy transfer mechanisms that occur at peak power densities near or above the surface plasma ignition thresholds. As shown, these plasma waves are periodically building up, expanding and recombining during the short time intervals between subsequent pulses, even in the case of the highest repetition rates that are presently limited to 100 Hz. Besides the efficient thermal energy transfer through plasma enhanced thermal coupling mechanisms, the simultaneously induced mechanical pressure waves are providing an additional impulsive loading of the targets. These pressures were investigated by using PVDF gauges. The experiments reveal that these effects are also responsible for improvements, concerning the energy balance, in most manufacturing processes such as in cutting or in drilling, where these fast thermomechanically coupled processes, for example, contribute to increase the mass removal rates.

  3. Experimental studies of high-average-power pulsed CO2-laser-induced thermomechanical processes

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, Manfred

    1990-10-01

    Pulsed high average power C02-lasers allow for a most efficient conversion of coherent IR-laser radiation into thermal and mechanical energies. This paper is concerned with investigations using a specially developed repetitively pulsed high energy C02-laser. This powerful device provides mean powers of several kW and peak powers of the individual pulses in the multi-MW range. Studies were performed to obtain information on the transient behaviour of the fast energy transfer mechanisms that occur at peak power densities near or above the surface plasma ignition thresholds. As shown, these plasma waves are periodically building up, expanding and recombining during the short time intervals between subsequent pulses, even in case of the highest repetition rates that are presently limited to 100 Hz. Besides the efficient thermal energy transfer through plasma-enhanced thermal coupling mechanisms, the simultaneously induced mechanical pressure waves are providing an additional impulsive loading of the targets. These pressures were investigated by using PVDF gauges. The experiments reveal that these effects too are responsible for improvements, concerning the energy balance, in most manufacturing processes such as in cutting or in drilling, where these fast thermo-mechanically coupled processes, for example, contribute to increase the mass removal rates.

  4. The influence of seat configuration on maximal average crank power during pedaling: a simulation study.

    PubMed

    Rankin, Jeffery W; Neptune, Richard R

    2010-11-01

    Manipulating seat configuration (i.e., seat tube angle, seat height and pelvic orientation) alters the bicycle-rider geometry, which influences lower extremity muscle kinematics and ultimately muscle force and power generation during pedaling. Previous studies have sought to identify the optimal configuration, but isolating the effects of specific variables on rider performance from the confounding effect of rider adaptation makes such studies challenging. Of particular interest is the influence of seat tube angle on rider performance, as seat tube angle varies across riding disciplines (e.g., road racers vs. triathletes). The goals of the current study were to use muscle-actuated forward dynamics simulations of pedaling to 1) identify the overall optimal seat configuration that produces maximum crank power and 2) systematically vary seat tube angle to assess how it influences maximum crank power. The simulations showed that a seat height of 0.76 m (or 102% greater than trochanter height), seat tube angle of 85.1 deg, and pelvic orientation of 20.5 deg placed the major power-producing muscles on more favorable regions of the intrinsic force-length-velocity relationships to generate a maximum average crank power of 981 W. However, seat tube angle had little influence on crank power, with maximal values varying at most by 1% across a wide range of seat tube angles (65 to 110 deg). The similar power values across the wide range of seat tube angles were the result of nearly identical joint kinematics, which occurred using a similar optimal seat height and pelvic orientation while systematically shifting the pedal angle with increasing seat tube angles. PMID:21245509

  5. 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. PMID:26030570

  6. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  7. Laser properties of an improved average-power Nd-doped phosphate glass

    NASA Astrophysics Data System (ADS)

    Payne, Stephen A.; Marshall, Christopher D.; Bayramian, Andy J.; Wilke, Gary D.; Hayden, Joseph S.

    1994-10-01

    The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties (expansion, conduction, fracture toughness, and Young's modulus), and by direct thermally induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% gain cross section and a 25% longer low-concentration emission lifetime.

  8. Specification of optical components for a high average-power laser environment

    SciTech Connect

    Taylor, J.R.; Chow, R.; Rinmdahl, K.A.; Willis, J.B.; Wong, J.N.

    1997-06-25

    Optical component specifications for the high-average-power lasers and transport system used in the Atomic Vapor Laser Isotope Separation (AVLIS) plant must address demanding system performance requirements. The need for high performance optics has to be balanced against the practical desire to reduce the supply risks of cost and schedule. This is addressed in optical system design, careful planning with the optical industry, demonstration of plant quality parts, qualification of optical suppliers and processes, comprehensive procedures for evaluation and test, and a plan for corrective action.

  9. Full Rank Solutions for the MIMO Gaussian Wiretap Channel With an Average Power Constraint

    NASA Astrophysics Data System (ADS)

    Fakoorian, S. Ali. A.; Swindlehurst, A. Lee

    2013-05-01

    This paper considers a multiple-input multiple-output (MIMO) Gaussian wiretap channel model, where there exists a transmitter, a legitimate receiver and an eavesdropper, each equipped with multiple antennas. In this paper, we first revisit the rank property of the optimal input covariance matrix that achieves the secrecy capacity of the multiple antenna MIMO Gaussian wiretap channel under the average power constraint. Next, we obtain necessary and sufficient conditions on the MIMO wiretap channel parameters such that the optimal input covariance matrix is full-rank, and we fully characterize the resulting covariance matrix as well. Numerical results are presented to illustrate the proposed theoretical findings.

  10. Yttrium Calcium Oxyborate for high average power frequency doubling and OPCPA

    SciTech Connect

    Liao, Z M; Jovanovic, I; Ebbers, C A; Bayramian, A; Schaffers, K; Caird, J; Bibeau, C; Barty, C J; Fei, Y; Chai, B

    2006-06-20

    Significant progress has been achieved recently in the growth of Yttrium Calcium Oxyborate (YCOB) crystals. Boules have been grown capable of producing large aperture nonlinear crystal plates suitable for high average power frequency conversion or optical parametric chirped pulse amplification (OPCPA). With a large aperture (5.5 cm x 8.5 cm) YCOB crystal we have demonstrated a record 227 W of 523.5nm light (22.7 J/pulse, 10 Hz, 14 ns). We have also demonstrated the applicability of YCOB for 1053 nm OPCPA.

  11. Method and system for modulation of gain suppression in high average power laser systems

    DOEpatents

    Bayramian, Andrew James

    2012-07-31

    A high average power laser system with modulated gain suppression includes an input aperture associated with a first laser beam extraction path and an output aperture associated with the first laser beam extraction path. The system also includes a pinhole creation laser having an optical output directed along a pinhole creation path and an absorbing material positioned along both the first laser beam extraction path and the pinhole creation path. The system further includes a mechanism operable to translate the absorbing material in a direction crossing the first laser beam extraction laser path and a controller operable to modulate the second laser beam.

  12. High average power pulsed phase conjugate laser with birefringence correction. Revision 1

    SciTech Connect

    Bowers, M.W.; Hankla, A.K.; Jacobson, G.F.

    1994-05-01

    Nd:YAG rod lasers have been plagued with the inability to go to high average powers because of thermally induced birefringence and focusing. Several methods have been employed to correct for the birefringence and the thermal aberrations of such systems, but place stringent constraints on the laser heads and/or the system alignment. They have developed a scalable Nd: YAG master oscillator/power amplifier (MOPA) laser system which employs a novel phase conjugation scheme to correct both for the material and thermal distortions as well as the thermal birefringence in double pass amplifier systems. This method reduces the double pass depolarization from 42% to less than 2% and is easy to align.

  13. A High-Average-Power Free Electron Laser for Microfabrication and Surface Applications

    NASA Technical Reports Server (NTRS)

    Dylla, H. F.; Benson, S.; Bisognano, J.; Bohn, C. L.; Cardman, L.; Engwall, D.; Fugitt, J.; Jordan, K.; Kehne, D.; Li, Z.; Liu, H.; Merminga, L.; Neil, G. R.; Neuffer, D.; Shinn, M.; Sinclair, C.; Wiseman, M.; Brillson, L. J.; Henkel, D. P.; Helvajian, H.; Kelley, M. J.; Nair, Shanti

    1995-01-01

    CEBAF has developed a comprehensive conceptual design of an industrial user facility based on a kilowatt ultraviolet (UV) (160-1000 mm) and infrared (IR) (2-25 micron) free electron laser (FEL) driven by a recirculating, energy recovering 200 MeV superconducting radio frequency (SRF) accelerator. FEL users, CEBAF's partners in the Lase Processing Consortium, including AT&T, DuPont, IBM, Northrop Grumman, 3M, and Xerox, are developing applications such as metal, ceramic, and electronic material micro-fabrication and polymer and metal surface processing, with the overall effort leading to later scale-up to industrial systems at 50-100 kW. Representative applications are described. The proposed high-average-power FEL overcomes limitations of conventional laser sources in available power, cost-effectiveness, tunability, and pulse structure.

  14. High-power femtosecond-terahertz pulse induces a wound response in mouse skin

    PubMed Central

    Kim, Kyu-Tae; Park, Jaehun; Jo, Sung Jin; Jung, Seonghoon; Kwon, Oh Sang; Gallerano, Gian Piero; Park, Woong-Yang; Park, Gun-Sik

    2013-01-01

    Terahertz (THz) technology has emerged for biomedical applications such as scanning, molecular spectroscopy, and medical imaging. Although a thorough assessment to predict potential concerns has to precede before practical utilization of THz source, the biological effect of THz radiation is not yet fully understood with scant related investigations. Here, we applied a femtosecond-terahertz (fs-THz) pulse to mouse skin to evaluate non-thermal effects of THz radiation. Analysis of the genome-wide expression profile in fs-THz-irradiated skin indicated that wound responses were predominantly mediated by transforming growth factor-beta (TGF-β) signaling pathways. We validated NFκB1- and Smad3/4-mediated transcriptional activation in fs-THz-irradiated skin by chromatin immunoprecipitation assay. Repeated fs-THz radiation delayed the closure of mouse skin punch wounds due to up-regulation of TGF-β. These findings suggest that fs-THz radiation initiate a wound-like signal in skin with increased expression of TGF-β and activation of its downstream target genes, which perturbs the wound healing process in vivo. PMID:23907528

  15. High-power femtosecond-terahertz pulse induces a wound response in mouse skin

    NASA Astrophysics Data System (ADS)

    Kim, Kyu-Tae; Park, Jaehun; Jo, Sung Jin; Jung, Seonghoon; Kwon, Oh Sang; Gallerano, Gian Piero; Park, Woong-Yang; Park, Gun-Sik

    2013-08-01

    Terahertz (THz) technology has emerged for biomedical applications such as scanning, molecular spectroscopy, and medical imaging. Although a thorough assessment to predict potential concerns has to precede before practical utilization of THz source, the biological effect of THz radiation is not yet fully understood with scant related investigations. Here, we applied a femtosecond-terahertz (fs-THz) pulse to mouse skin to evaluate non-thermal effects of THz radiation. Analysis of the genome-wide expression profile in fs-THz-irradiated skin indicated that wound responses were predominantly mediated by transforming growth factor-beta (TGF-β) signaling pathways. We validated NFκB1- and Smad3/4-mediated transcriptional activation in fs-THz-irradiated skin by chromatin immunoprecipitation assay. Repeated fs-THz radiation delayed the closure of mouse skin punch wounds due to up-regulation of TGF-β. These findings suggest that fs-THz radiation initiate a wound-like signal in skin with increased expression of TGF-β and activation of its downstream target genes, which perturbs the wound healing process in vivo.

  16. Welding of transparent polymers using femtosecond laser

    NASA Astrophysics Data System (ADS)

    Roth, Gian-Luca; Rung, Stefan; Hellmann, Ralf

    2016-02-01

    Based on nonlinear absorption, we report on laser welding of cycloolefin copolymers without any additional absorption layer employing infrared femtosecond laser. To the best of our knowledge, this is the first report of ultrashort laser welding of this material class, revealing a remarkable high processing speed of 20 mm/s in a single pass mode. Using a 1028 nm laser having a pulse duration of 220 fs at a repetition rate of 571 kHz leads to a welding seam width between 38 and 137 μm, depending on the applied laser average power. The welded joint is characterized by a maximum shear strength of 40 MPa. The experimental results are compared to those reported for femtosecond laser welding of PMMA and to those published for using a Thulium fiber laser.

  17. The ETA-II induction linac as a high-average-power FEL driver

    NASA Astrophysics Data System (ADS)

    Nexsen, W. E.; Atkinson, D. P.; Barrett, D. M.; Chen, Y.-J.; Clark, J. C.; Griffith, L. V.; Kirbie, H. C.; Newton, M. A.; Paul, A. C.; Sampayan, S.; Throop, A. L.; Turner, W. C.

    1990-10-01

    The Experimental Test Accelerator II (ETA-II) is the first induction linac designed specifically to FEL requirements. It is primarily intended to demonstrate induction accelerator technology for high-average-power, high-brightness electron beams, and will be used to drive a 140 and 250 GHz microwave FEL for plasma heating experiments in the Microwave Tokamak Experiment (MTX) at LLNL. Its features include high-vacuum design which allows the use of an intrinsically bright dispenser cathode, induction cells designed to minimize BBU growth rate, and careful attention to magnetic alignment to minimize radial sweep due to beam corkscrew. The use of magnetic switches allows high-average-power operation. At present ETA-II is being used to drive 140 GHz plasma heating experiments. These experiments require nominal beam parameters of 6 MeV energy, 2 kA current, 20 ns pulse width and a brightness of 1 × 108 A/(m rad)2 at the wiggler with a pulse repetition frequency (prf) of 0.5 Hz. Future 250 GHz experiments require beam parameters of 10 MeV energy, 3 kA current, 50 ns pulse width and a brightness of 1 × 108 A/(m rad)2 with a 5 kHz prf for 0.5 s. In this paper we discuss the present status of ETA-II parameters and the phased development program necessary to satisfy these future requirements.

  18. Green sub-ps laser exceeding 400 W of average power

    NASA Astrophysics Data System (ADS)

    Gronloh, Bastian; Russbueldt, Peter; Jungbluth, Bernd; Hoffmann, Hans-Dieter

    2014-02-01

    We present the world's first laser at 515 nm with sub-picosecond pulses and an average power of 445 W. To realize this beam source we utilize an Yb:YAG-based infrared laser consisting of a fiber MOPA system as a seed source, a rod-type pre-amplifier and two Innoslab power amplifier stages. The infrared system delivers up to 930 W of average power at repetition rates between 10 and 50 MHz and with pulse durations around 800 fs. The beam quality in the infrared is M² = 1.1 and 1.5 in fast and slow axis. As a frequency doubler we chose a Type-I critically phase-matched Lithium Triborate (LBO) crystal in a single-pass configuration. To preserve the infrared beam quality and pulse duration, the conversion was carefully modeled using numerical calculations. These take dispersion-related and thermal effects into account, thus enabling us to provide precise predictions of the properties of the frequency-doubled beam. To be able to model the influence of thermal dephasing correctly and to choose appropriate crystals accordingly, we performed extensive absorption measurements of all crystals used for conversion experiments. These measurements provide the input data for the thermal FEM analysis and calculation. We used a Photothermal Commonpath Interferometer (PCI) to obtain space-resolved absorption data in the bulk and at the surfaces of the LBO crystals. The absorption was measured at 1030 nm as well as at 515 nm in order to take into account the different absorption behavior at both occurring wavelengths.

  19. Yb3+ doped ribbon fiber for high-average power lasers and amplifiers

    NASA Astrophysics Data System (ADS)

    Drachenberg, Derrek R.; Messerly, Michael J.; Pax, Paul H.; Sridharan, Arun K.; Tassano, John B.; Dawson, Jay W.

    2014-03-01

    Diffraction-limited high power lasers in the region of 10s of kW to greater than 100 kW are needed for defense, manufacturing and future science applications. A balance of thermal lensing and Stimulated Brillouin Scattering (SBS) for narrowband amplifiers and Stimulated Raman Scattering (SRS) for broadband amplifiers is likely to limit the average power of circular core fiber amplifiers to 2 kW (narrowband) or 36 kW (broadband). A ribbon fiber, which has a rectangular core, operating in a high order mode can overcome these obstacles by increasing mode area without becoming thermal lens limited and without the on-axis intensity peak associated with circular high order modes. High order ribbon fiber modes can also be converted to a fundamental Gaussian mode with high efficiency for applications in which this is necessary. We present an Yb-doped, air clad, optical fiber having an elongated, ribbon-like core having an effective mode area of area of 600 μm² and an aspect ratio of 13:1. As an amplifier, the fiber produced 50% slope efficiency and a seed-limited power of 10.5 W, a gain of 24 dB. As an oscillator, the fiber produced multimode power above 40 W with 71% slope efficiency and single mode power above 5 W with 44% slope efficiency. The multimode M2 beam quality factor of the fiber was 1.6 in the narrow dimension and 15 in the wide dimension.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  1. Non-Invasive Beam Detection in a High-Average Power Electron Accelerator

    NASA Astrophysics Data System (ADS)

    Williams, Joel; Biedron, Sandra; Harris, John; Martinez, Jorge; Milton, Stephen; Benson, S.; Evtushenko, P.; Neil, G.; Zhang, S.

    2014-03-01

    For a free-electron laser (FEL) to work effectively the electron beam quality must meet exceptional standards. In the case of an FEL operating at infrared wavelengths the critical phase space tends to be in the longitudinal direction. Achieving high enough longitudinal phase space density directly from the electron injector system in an FEL is difficult due to space charge effects, thus one needs to manipulate the longitudinal phase space once the beam energy reaches a sufficiently high value. However, this is fraught with problems. Longitudinal space charge and coherent synchrotron radiation can both disrupt the overall phase space, furthermore, the phase space disruption is exacerbated by the longitudinal phase space manipulation process required to achieve high peak current. To achieve and maintain good FEL performance, one needs to investigate the longitudinal emittance during operation, preferably in a non-invasive manner. Using electro-optical (EO) methods, we plan to measure the bunch longitudinal profile of an energy (~120-MeV), high-power (~10 kW or more average FEL output power) beam. Such a diagnostic could be critical in efforts to diagnose and help mitigate deleterious beam effects for high output power FELs.

  2. Thermally induced distortion of high average power laser system by an optical transport system

    SciTech Connect

    Ault, L; Chow, R; Taylor, Jedlovec, D

    1999-03-31

    The atomic vapor laser isotope separation process uses high-average power lasers that have the commercial potential to enrich uranium for the electric power utilities. The transport of the laser beam through the laser system to the separation chambers requires high performance optical components, most of which have either fused silica or Zerodur as the substrate material. One of the requirements of the optical components is to preserve the wavefront quality of the laser beam that propagate over long distances. Full aperture tests with the high power process lasers and finite element analysis (FEA) have been performed on the transport optics. The wavefront distortions of the various sections of the transport path were measured with diagnostic Hartmann sensor packages. The FEA results were derived from an in-house thermal-structural-optical code which is linked to the commercially available CodeV program. In comparing the measured and predicted results, the bulk absorptance of fused silica was estimated to about 50 ppm/cm in the visible wavelength regime. Wavefront distortions are reported on optics made from fused silica and Zerodur substrate materials.

  3. 1KHz high average power single-frequency Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaolei; Ma, Xiuhua; Li, Shiguang; Chen, Weibiao

    2015-02-01

    A laser-diode-pumped master oscillator and power amplifier was developed with high efficiency, high average power and high beam quality. The oscillator is an injection-seeding, fiber coupled diode-end-pumped E-O Q-switched Nd:YAG laser, producing single frequency pulse laser output with pulse energy of 8mJ and pulse width of 11ns at a pulse repetition rate of 1KHz,The 1KHz was divided into four chains with frequency of 250Hz, through E-O modulation technology, The power amplifier utilizes conductively-cooling Nd:YAG zigzag slab with two sides' pump architecture at bounce point. Pulse energy of more than 800mJ with pulse widths of 12.6ns was obtained at repetition rate of 250Hz in every amplifier chain, the frequency-doubled pulse energy of 360mJ when KTP crystal was used was obtained at a repetition of 250Hz.

  4. Sub-100 fs high average power directly blue-diode-laser-pumped Ti:sapphire oscillator

    NASA Astrophysics Data System (ADS)

    Rohrbacher, Andreas; Markovic, Vesna; Pallmann, Wolfgang; Resan, Bojan

    2016-03-01

    Ti:sapphire oscillators are a proven technology to generate sub-100 fs (even sub-10 fs) pulses in the near infrared and are widely used in many high impact scientific fields. However, the need for a bulky, expensive and complex pump source, typically a frequency-doubled multi-watt neodymium or optically pumped semiconductor laser, represents the main obstacle to more widespread use. The recent development of blue diodes emitting over 1 W has opened up the possibility of directly diode-laser-pumped Ti:sapphire oscillators. Beside the lower cost and footprint, a direct diode pumping provides better reliability, higher efficiency and better pointing stability to name a few. The challenges that it poses are lower absorption of Ti:sapphire at available diode wavelengths and lower brightness compared to typical green pump lasers. For practical applications such as bio-medicine and nano-structuring, output powers in excess of 100 mW and sub-100 fs pulses are required. In this paper, we demonstrate a high average power directly blue-diode-laser-pumped Ti:sapphire oscillator without active cooling. The SESAM modelocking ensures reliable self-starting and robust operation. We will present two configurations emitting 460 mW in 82 fs pulses and 350 mW in 65 fs pulses, both operating at 92 MHz. The maximum obtained pulse energy reaches 5 nJ. A double-sided pumping scheme with two high power blue diode lasers was used for the output power scaling. The cavity design and the experimental results will be discussed in more details.

  5. Adaptive Control for Buck Power Converter Using Fixed Point Inducting Control and Zero Average Dynamics Strategies

    NASA Astrophysics Data System (ADS)

    Hoyos Velasco, Fredy Edimer; García, Nicolás Toro; Garcés Gómez, Yeison Alberto

    In this paper, the output voltage of a buck power converter is controlled by means of a quasi-sliding scheme. The Fixed Point Inducting Control (FPIC) technique is used for the control design, based on the Zero Average Dynamics (ZAD) strategy, including load estimation by means of the Least Mean Squares (LMS) method. The control scheme is tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The closed loop system shows adequate performance. The experimental and simulation results match. The main contribution of this paper is to introduce the load estimator by means of LMS, to make ZAD and FPIC control feasible in load variation conditions. In addition, comparison results for controlled buck converter with SMC, PID and ZAD-FPIC control techniques are shown.

  6. An automatic step adjustment method for average power analysis technique used in fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Ming

    2006-04-01

    An automatic step adjustment (ASA) method for average power analysis (APA) technique used in fiber amplifiers is proposed in this paper for the first time. In comparison with the traditional APA technique, the proposed method has suggested two unique merits such as a higher order accuracy and an ASA mechanism, so that it can significantly shorten the computing time and improve the solution accuracy. A test example demonstrates that, by comparing to the APA technique, the proposed method increases the computing speed by more than a hundredfold under the same errors. By computing the model equations of erbium-doped fiber amplifiers, the numerical results show that our method can improve the solution accuracy by over two orders of magnitude at the same amplifying section number. The proposed method has the capacity to rapidly and effectively compute the model equations of fiber Raman amplifiers and semiconductor lasers.

  7. High average power CW FELs (Free Electron Laser) for application to plasma heating: Designs and experiments

    SciTech Connect

    Booske, J.H.; Granatstein, V.L.; Radack, D.J.; Antonsen, T.M. Jr.; Bidwell, S.; Carmel, Y.; Destler, W.W.; Latham, P.E.; Levush, B.; Mayergoyz, I.D.; Zhang, Z.X. . Lab. for Plasma Research); Freund, H.P. )

    1989-01-01

    A short period wiggler (period {approximately} 1 cm), sheet beam FEL has been proposed as a low-cost source of high average power (1 MW) millimeter-wave radiation for plasma heating and space-based radar applications. Recent calculation and experiments have confirmed the feasibility of this concept in such critical areas as rf wall heating, intercepted beam ( body'') current, and high voltage (0.5 - 1 MV) sheet beam generation and propagation. Results of preliminary low-gain sheet beam FEL oscillator experiments using a field emission diode and pulse line accelerator have verified that lasing occurs at the predicted FEL frequency. Measured start oscillation currents also appear consistent with theoretical estimates. Finally, we consider the possibilities of using a short-period, superconducting planar wiggler for improved beam confinement, as well as access to the high gain, strong pump Compton regime with its potential for highly efficient FEL operation.

  8. Status of HiLASE project: High average power pulsed DPSSL systems for research and industry

    NASA Astrophysics Data System (ADS)

    Mocek, T.; Divoky, M.; Smrz, M.; Sawicka, M.; Chyla, M.; Sikocinski, P.; Vohnikova, H.; Severova, P.; Lucianetti, A.; Novak, J.; Rus, B.

    2013-11-01

    We introduce the Czech national R&D project HiLASE which focuses on strategic development of advanced high-repetition rate, diode pumped solid state laser (DPSSL) systems that may find use in research, high-tech industry and in the future European large-scale facilities such as HiPER and ELI. Within HiLASE we explore two major concepts: thin-disk and cryogenically cooled multislab amplifiers capable of delivering average output powers above 1 kW level in picosecond-to-nanosecond pulsed regime. In particular, we have started a programme of technology development to demonstrate the scalability of multislab concept up to the kJ level at repetition rate of 1-10 Hz.

  9. A Method for the Estimation of p-Mode Parameters from Averaged Solar Oscillation Power Spectra

    NASA Astrophysics Data System (ADS)

    Reiter, J.; Rhodes, E. J., Jr.; Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Larson, T. P.

    2015-04-01

    A new fitting methodology is presented that is equally well suited for the estimation of low-, medium-, and high-degree mode parameters from m-averaged solar oscillation power spectra of widely differing spectral resolution. This method, which we call the “Windowed, MuLTiple-Peak, averaged-spectrum” or WMLTP Method, constructs a theoretical profile by convolving the weighted sum of the profiles of the modes appearing in the fitting box with the power spectrum of the window function of the observing run, using weights from a leakage matrix that takes into account observational and physical effects, such as the distortion of modes by solar latitudinal differential rotation. We demonstrate that the WMLTP Method makes substantial improvements in the inferences of the properties of the solar oscillations in comparison with a previous method, which employed a single profile to represent each spectral peak. We also present an inversion for the internal solar structure, which is based upon 6366 modes that we computed using the WMLTP method on the 66 day 2010 Solar and Heliospheric Observatory/MDI Dynamics Run. To improve both the numerical stability and reliability of the inversion, we developed a new procedure for the identification and correction of outliers in a frequency dataset. We present evidence for a pronounced departure of the sound speed in the outer half of the solar convection zone and in the subsurface shear layer from the radial sound speed profile contained in Model S of Christensen-Dalsgaard and his collaborators that existed in the rising phase of Solar Cycle 24 during mid-2010.

  10. Tunable, high-repetition-rate, femtosecond pulse generation in the ultraviolet.

    PubMed

    Ghotbi, M; Esteban-Martin, A; Ebrahim-Zadeh, M

    2008-02-15

    We report efficient generation of tunable femtosecond pulses in the ultraviolet (UV) by intracavity doubling of a visible femtosecond optical parametric oscillator (OPO). The OPO, based on a 400 microm BiB3O6 crystal and pumped at 415 nm in the blue, can provide visible femtosecond signal pulses across 500-710 nm. Using a 500 microm crystal of beta-BaB2O4 internal to the OPO cavity, efficient frequency doubling of the signal pulses into the UV is achieved, providing tunable femtosecond pulses across 250-355 nm with up to 225 mW of average power at 76 MHz. Cross-correlation measurements result in UV pulses with durations down to 132 fs for 180 fs blue pump pulses. PMID:18278105

  11. Wavefront control in high average-power multi-slab laser system

    NASA Astrophysics Data System (ADS)

    Pilar, Jan; Bonora, Stefano; Divoky, Martin; Phillips, Jonathan; Smith, Jodie; Ertel, Klaus; Collier, John; Jelinkova, Helena; Lucianetti, Antonio; Mocek, TomáÅ.¡

    2015-03-01

    A high average power cryogenically-cooled diode-pumped solid-state laser system for Hilase centre in Czech Republic is being developed by Central Laser Facility at Rutherford Appleton Laboratory, England in collaboration with Hilase team. The system will deliver pulses with energy of 100 J at 10 Hz repetition rate and will find applications in research and industry. The laser medium and other elements of the system are subject to heavy thermal loading which causes serious optical aberrations and degrade the output beam quality. To meet the stringent laser requirements of this kWclass laser, it is necessary to implement adaptive optics system, which will correct for these aberrations. During our research the sources of aberrations have been identified and analyzed. Based on this analysis, a suitable adaptive optics system was proposed. After finalizing numerical models, simulations and optimizations, the adaptive optics system was developed, characterized and installed in a cryogenically-cooled multi-slab laser system running up to 6 J and 10 Hz. The adaptive optics system consists of 6x6 actuator bimorph deformable mirror and wavefront sensor based on quadriwave lateral shearing interferometry operated in closed loop. The functionality of the system was demonstrated at full power.

  12. 800-keV Electron Induction Injector with High Average Power

    NASA Astrophysics Data System (ADS)

    Mamaev, G. L.; Glazov, A. I.; Krasnopolsky, V. A.; Latypov, T. A.; Mamaev, S. L.; Puchkov, S. N.; Shcherbakov, A. M.; Tenyakov, I. E.; Terechkin, Y. M.; Vlasenko, S. I.

    1997-05-01

    Design parameters of the induction injector are 800 keV beam energy, 2...5 kA current, 80 ns pulse flat top and 100 Hz repetition rate. The average beam power of the series of pulses is 40 kW. The injector modules use metglass cores. The electron source mounted on the stem consists of a 80 mm diameter velvet cathode placed on a field forming electrode. The tapered insulator assembly separates the oil-filled induction modules from the vacuum diode. The magnetic field necessary for beam extraction is generated by two magntic cores. 150 kV, 40 kA, 100 ns, 100 Hz pulse generator has been designed in Radiotechnical institute. The generator is a two-stage magnetic power compressor with a thyratron switch. The voltage pulse is produced by the water-filled pulse forming line (PFL) with the impedance of 3.3 ohm. The calculated parameters of the injector, the design features of its modules and the experimental results of their testing are presented.

  13. Femtosecond mode-locked holmium fiber laser pumped by semiconductor disk laser.

    PubMed

    Chamorovskiy, A; Marakulin, A V; Ranta, S; Tavast, M; Rautiainen, J; Leinonen, T; Kurkov, A S; Okhotnikov, O G

    2012-05-01

    We report on a 2085 nm holmium-doped silica fiber laser passively mode-locked by semiconductor saturable absorber mirror and carbon nanotube absorber. The laser, pumped by a 1.16 μm semiconductor disk laser, produces 890 femtosecond pulses with the average power of 46 mW and the repetition rate of 15.7 MHz. PMID:22555700

  14. Femtosecond soliton source with fast and broad spectral tunability.

    PubMed

    Masip, Martin E; Rieznik, A A; König, Pablo G; Grosz, Diego F; Bragas, Andrea V; Martinez, Oscar E

    2009-03-15

    We present a complete set of measurements and numerical simulations of a femtosecond soliton source with fast and broad spectral tunability and nearly constant pulse width and average power. Solitons generated in a photonic crystal fiber, at the low-power coupling regime, can be tuned in a broad range of wavelengths, from 850 to 1200 nm using the input power as the control parameter. These solitons keep almost constant time duration (approximately 40 fs) and spectral widths (approximately 20 nm) over the entire measured spectra regardless of input power. Our numerical simulations agree well with measurements and predict a wide working wavelength range and robustness to input parameters. PMID:19282951

  15. Industrial applications of high-average power high-peak power nanosecond pulse duration Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Harrison, Paul M.; Ellwi, Samir

    2009-02-01

    Within the vast range of laser materials processing applications, every type of successful commercial laser has been driven by a major industrial process. For high average power, high peak power, nanosecond pulse duration Nd:YAG DPSS lasers, the enabling process is high speed surface engineering. This includes applications such as thin film patterning and selective coating removal in markets such as the flat panel displays (FPD), solar and automotive industries. Applications such as these tend to require working spots that have uniform intensity distribution using specific shapes and dimensions, so a range of innovative beam delivery systems have been developed that convert the gaussian beam shape produced by the laser into a range of rectangular and/or shaped spots, as required by demands of each project. In this paper the authors will discuss the key parameters of this type of laser and examine why they are important for high speed surface engineering projects, and how they affect the underlying laser-material interaction and the removal mechanism. Several case studies will be considered in the FPD and solar markets, exploring the close link between the application, the key laser characteristics and the beam delivery system that link these together.

  16. Diode-pumped gigahertz femtosecond Yb:KGW laser with a peak power of 3.9 kW.

    PubMed

    Pekarek, Selina; Fiebig, Christian; Stumpf, Max Christoph; Oehler, Andreas Ernst Heinz; Paschke, Katrin; Erbert, Götz; Südmeyer, Thomas; Keller, Ursula

    2010-08-01

    We present a diode-pumped Yb:KGW laser with a repetition rate of 1 GHz and a pulse duration of 281 fs at a wavelength of 1041 nm. A high brightness distributed Bragg reflector tapered diode laser is used as a pump source. Stable soliton modelocking is achieved with a semiconductor saturable absorber mirror (SESAM). The obtained average output power is 1.1 W and corresponds to a peak power of 3.9 kW and a pulse energy of 1.1 nJ. With harmonic modelocking we could increase the pulse repetition rate up to 4 GHz with an average power of 900 mW and a pulse duration of 290 fs. This Yb:KGW laser has a high potential for stable frequency comb generation. PMID:20721018

  17. 1 MHz repetition rate hollow fiber pulse compression to sub-100-fs duration at 100 W average power.

    PubMed

    Rothhardt, Jan; Hädrich, Steffen; Carstens, Henning; Herrick, Nicholas; Demmler, Stefan; Limpert, Jens; Tünnermann, Andreas

    2011-12-01

    We report on nonlinear pulse compression at very high average power. A high-power fiber chirped pulse amplification system based on a novel large pitch photonic crystal fiber delivers 700 fs pulses with 200 μJ pulse energy at a 1 MHz repetition rate, resulting in 200 W of average power. Subsequent spectral broadening in a xenon-filled hollow-core fiber and pulse compression with chirped mirrors is employed for pulse shortening and peak power enhancement. For the first time, to our knowledge, more than 100 W of average power are transmitted through a noble-gas-filled hollow fiber. After pulse compression of 81 fs, 93 μJ pulses are obtained at a 1 MHz repetition rate. PMID:22139257

  18. Sub-700fs pulses at 152 W average power from a Tm-doped fiber CPA system

    NASA Astrophysics Data System (ADS)

    Gaida, Christian; Stutzki, Fabian; Gebhardt, Martin; Jansen, Florian; Wienke, Andreas; Zeitner, Uwe D.; Fuchs, Frank; Jauregui, Cesar; Wandt, Dieter; Kracht, Dietmar; Limpert, Jens; Tünnermann, Andreas

    2015-03-01

    Thulium-based fiber lasers potentially provide for the demand of high average-power ultrafast laser systems operating at an emission wavelength around 2 μm. In this work we use a Tm-doped photonic-crystal fiber (PCF) with a mode field diameter of 36 μm enabling high peak powers without the onset of detrimental nonlinear effects. For the first time a Tmdoped PCF amplifier allows for a pump-power limited average output power of 241 W with a slope efficiency above 50%, good beam quality and linear polarization. A record compressed average power of 152 W and a pulse peak power of more than 4 MW at sub-700 fs pulse duration are enabled by dielectric gratings with diffraction efficiencies higher than 98% leading to a total compression efficiency of more than 70%. A further increase of pulse peak power towards the GW-level is planned by employing Tm-doped large-pitch fibers with mode field diameters well above 50 μm. The coherent combination of ultrafast pulses might eventually lead to kW-level average power and multi-GW peak power.

  19. Laser properties of a new average-power Nd-doped phosphate glass

    NASA Astrophysics Data System (ADS)

    Payne, S. A.; Marshall, C. D.; Bayramian, A.; Wilke, G. D.; Hayden, J. S.

    1995-09-01

    The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially available Average-Power Glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties (expansion, conduction, fracture toughness, and Young's modulus), and by direct thermally induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime. Other measurements pertaining to the concentration quenching, thermal lensing, and saturation of the extraction are also described in this article. It is note-worthy that APG-t offers increased bandwidth near the peak of the 1054 nm gain spectrum, suggesting that this material may have special utility as a means of generating and amplifying ultrashort pulses of light.

  20. NEO-LISP: Deflecting near-earth objects using high average power, repetitively pulsed lasers

    SciTech Connect

    Phipps, C.R.; Michaelis, M.M.

    1994-10-01

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime, (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory, and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA`s) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  1. Development of a High-Average-Power Compton Gamma Source for Lepton Colliders

    SciTech Connect

    Pogorelsky, Igor; Polyanskiy, Mikhail N.; Yakimenko, Vitaliy; Platonenko, Viktor T.

    2009-01-22

    Gamma-({gamma}{sup -}) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A {gamma}-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition {gamma}-source assumes placing the Compton interaction point inside a CO{sub 2} laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of {gamma}-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO{sub 2}-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO{sub 2} laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO{sub 2} laser pulses circulating inside the cavity that incorporates the Compton interaction point.

  2. Numerical simulation studies of the design and performance of the AFEL for high average power operation

    SciTech Connect

    Goldstein, J.C.; Takeda, H.; Nguyen, D.C.

    1994-10-01

    AFEL (Advanced Free-Electron Laser) at Los Alamos is a compact free-electron laser oscillator which utilizes a very high-brightness electron beam generated by a high gradient linac whose source of electrons is a photocathode injector. This device has been operating, with 15--17 MeV electrons, at optical wavelengths in the 4.5--6.0 {mu}m range, since April of 1993 with a one-centimeter-period, permanent-magnet wiggler which is 24 periods long. The linac produces about 12 {mu}s macropulses at a normal repetition rate of one Hz, while the micropulse repetition rate within a macropulse is 108.33 Mhz which is consistent with the optical cavity length of about 138.5 cm. A program is now underway to upgrade the subsystems of this laser in order to allow it to produce long-time-average optical output powers in the range of 0.1 to 1.0 kW. In this communication, we briefly indicate the details of the equipment upgrades, describe a new high-extraction-efficiency wiggler, and present the results of numerical simulation studies of the design.

  3. Industrial applications of a fiber-based high-average-power picosecond laser

    NASA Astrophysics Data System (ADS)

    Moorhouse, Colin

    2009-02-01

    Presently lasers are well established tools for materials processing due to advantages such as (i) the non-contact nature of the laser-material interaction, (ii) the high precision achievable and (iii) no requirement for high vacuum equipment or costly chemicals. Now, industrial laser users demand improvements in order to achieve higher quality features with reduced heat affected zones and so it is increasingly necessary to use shorter pulse durations. To satisfy these needs, there has been significant research into ultrafast laser technology for decades, however at this time, these lasers have yet to be adopted by industry for mass production. Recent developments have shown that the combination of a fibre seed oscillator and Diode Pumped Solid State (DPSS) amplifying technology can offer high average power, picosecond pulses (~10ps) in an industrially-rugged package. The significant laser design aspects are outlined here, along with the advantages this technology offers for applications such as silicon via drilling, thin film patterning and the machining of wide bandgap materials.

  4. NEO-LISP: Deflecting near-Earth objects using high average power, repetitively pulsed lasers

    NASA Astrophysics Data System (ADS)

    Phipps, C. R.; Michaelis, M. M.

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime; (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory; and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA's) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  5. Development of a High-Average-Power Compton Gamma Source for Lepton Colliders

    NASA Astrophysics Data System (ADS)

    Pogorelsky, Igor; Polyanskiy, Mikhail N.; Yakimenko, Vitaliy; Platonenko, Viktor T.

    2009-01-01

    Gamma- (γ-) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A γ-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition γ-source assumes placing the Compton interaction point inside a CO2 laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of γ-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO2-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO2 laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO2 laser pulses circulating inside the cavity that incorporates the Compton interaction point.

  6. Laser damage of dichroic coatings in a high average power laser vacuum resonator

    SciTech Connect

    Arnold, P A; Berzins, L V; Chow, R; Erbert, G V

    1999-07-28

    In our application, dichroics in a high average power, near-infrared, laser system have short operating lifetimes. These dichroics were used as the resonator fold mirrors and permitted the transmission of the pumping argon (Ar) ion laser light. Representative samples of two different dichroic optics were taken off-line and the transmission performance monitored in various scenarios. Irradiating these optics under resonator vacuum conditions, ({le}1 mT, 11.7 kW/cm{sup 2}, Ar laser running all wavelengths) resulted in a degradation of transmission with time. Irradiating these optics in a rarefied oxygen atmosphere (1 to 10 T of oxygen, 11.7 kW/cm{sup 2}, Ar laser running all wavelengths) the transmission remained steady over a period of days. The transmission loss observed in the optic tested in vacuum was somewhat reversible if the optic was subsequently irradiated in a rarefied oxygen atmosphere. This reversibility was only possible if the transmission degradation was not too severe. Further tests demonstrated that an atmosphere of 10 T of air also prevented the transmission degradation. In addition, tests were performed to demonstrate that the optic damage was not caused by the ultra-violet component in the Ar ion laser. Mechanisms that may account for this behavior are proposed.

  7. Gas-dynamic explosion of water microparticles under action high-power femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Zemlyanov, Alexander A.; Geints, Yuri E.; Apeksimov, Dmitrii V.

    2006-02-01

    Among the broad audience of problems of atmospheric nonlinear optics the important place is occupied with a problem about interaction of intensive laser radiation with water microparticles. Drops, being in a field of powerful light radiation, owing to effects of evaporation or explosion change the optical characteristics and influence on the optical properties of an environment. It results to that process and the distribution of intensive laser radiation in a particle is characterized by self-influence and is capable to change the internal power of a drop due to occurrence of areas of optical breakdown. In the report the model of destruction of water microparticles under action of supershort laser radiation is submitted. The physical contents of model is the effect of shock boiling up of a liquid at it gas-dynamic expansion from areas subject to optical breakdown.

  8. Design of a high average-power FEL driven by an existing 20 MV electrostatic-accelerator

    SciTech Connect

    Kimel, I.; Elias, L.R.

    1995-12-31

    There are some important applications where high average-power radiation is required. Two examples are industrial machining and space power-beaming. Unfortunately, up to date no FEL has been able to show more than 10 Watts of average power. To remedy this situation we started a program geared towards the development of high average-power FELs. As a first step we are building in our CREOL laboratory, a compact FEL which will generate close to 1 kW in CW operation. As the next step we are also engaged in the design of a much higher average-power system based on a 20 MV electrostatic accelerator. This FEL will be capable of operating CW with a power output of 60 kW. The idea is to perform a high power demonstration using the existing 20 MV electrostatic accelerator at the Tandar facility in Buenos Aires. This machine has been dedicated to accelerate heavy ions for experiments and applications in nuclear and atomic physics. The necessary adaptations required to utilize the machine to accelerate electrons will be described. An important aspect of the design of the 20 MV system, is the electron beam optics through almost 30 meters of accelerating and decelerating tubes as well as the undulator. Of equal importance is a careful design of the long resonator with mirrors able to withstand high power loading with proper heat dissipation features.

  9. High-average-power 266 nm generation with a KBe₂BO₃F₂ prism-coupled device.

    PubMed

    Wang, Lirong; Zhai, Naixia; Liu, Lijuan; Wang, Xiaoyang; Wang, Guiling; Zhu, Yong; Chen, Chuangtian

    2014-11-01

    High-average-power fourth harmonic generation (4thHG) of an Nd:YAG laser has been achieved by using a KBe₂BO₃F₂-prism-coupled device (KBBF-PCD) . The highest output power of 7.86 W at 266 nm was obtained with a conversion efficiency of 10%. To our knowledge, this is the highest power ever obtained by a KBBF-PCD. The stability of the 266 nm output power at 3.26 W was measured over a period of 60 minutes, and the standard deviation jitter of the average power was 1.4%. Moreover, the temperature bandwidth for KBBF was also measured at 266nm for the first time,which shows that KBBF has significant advantages in high power 4thHG compared to other major nonlinear optical crystals and is potential for UV applications. PMID:25401859

  10. High-speed photorefractive keratectomy with femtosecond ultraviolet pulses

    NASA Astrophysics Data System (ADS)

    Danieliene, Egle; Gabryte, Egle; Vengris, Mikas; Ruksenas, Osvaldas; Gutauskas, Algimantas; Morkunas, Vaidotas; Danielius, Romualdas

    2015-05-01

    Femtosecond near-infrared lasers are widely used for a number of ophthalmic procedures, with flap cutting in the laser-assisted in situ keratomileusis (LASIK) surgery being the most frequent one. At the same time, lasers of this type, equipped with harmonic generators, have been shown to deliver enough ultraviolet (UV) power for the second stage of the LASIK procedure, the stromal ablation. However, the speed of the ablation reported so far was well below the currently accepted standards. Our purpose was to perform high-speed photorefractive keratectomy (PRK) with femtosecond UV pulses in rabbits and to evaluate its predictability, reproducibility and healing response. The laser source delivered femtosecond 206 nm pulses with a repetition rate of 50 kHz and an average power of 400 mW. Transepithelial PRK was performed using two different ablation protocols, to a total depth of 110 and 150 μm. The surface temperature was monitored during ablation; haze dynamics and histological samples were evaluated to assess outcomes of the PRK procedure. For comparison, analogous excimer ablation was performed. Increase of the ablation speed up to 1.6 s/diopter for a 6 mm optical zone using femtosecond UV pulses did not significantly impact the healing process.

  11. Power-averaging method to characterize and upscale permeability in DFNs

    NASA Astrophysics Data System (ADS)

    De Dreuzy, J. R.; Davy, P.; Pichot, G.; Le Goc, R.; Maillot, J.; Darcel, C.; Meheust, Y.

    2015-12-01

    In a lot of geological environments, permeability is dominated by the existence of fractures and by their degree of interconnections. Flow properties depend mainly on the statistical properties of the fracture population (length, apertures, orientation), on the network topology, as well as on some detailed properties within fracture planes. None of them can be a priori discarded as fracture networks are potentially close to some percolation threshold. Still, most details are strongly homogenized by the inherent diffusive nature of flows. It should thus be possible to upscale permeability on the basis of a limited number of descriptors. Based on an extensive analysis of 2D and 3D DFNs as well as on reference connectivity structures, we investigate the relation between the local fracture structures and the effective permeability. On one hand poor connectivity, small intersections and fracture closures limit permeability. If these patterns control flow, permeability would derive from a suite of fracture in series dominated by its weakest element. Effective permeability could then be approached by the harmonic mean of the local permeabilities. On the other hand, extended fractures and locally higher fracture densities, enhance permeability. If these patterns control flow, all fractures would take equally part to flow and effective permeability would tend to the arithmetic mean of the local permeabilities. Defined as the relative weight between the two extreme harmonic and arithmetic means, the power-law averaging exponent gives a compact way to compare fracture network hydraulics. It may further lead to some comprehensive upscaling rules. Permeability is not only determined by global connectivity but also by more local effects. We measure them by defining a local connectivity index equal to the number of fracture connections at some reference local scale. Knowledge of the relative local to global effects should help optimizing characterization strategies.

  12. Broadband high-power mid-IR femtosecond pulse generation from an ytterbium-doped fiber laser pumped optical parametric amplifier.

    PubMed

    Hu, Chengzhi; Chen, Tao; Jiang, PeiPei; Wu, Bo; Su, Jianjia; Shen, Yonghang

    2015-12-15

    We report on a high-power periodically poled MgO-doped lithium niobate (MgO:PPLN)-based femtosecond optical parametric amplifier (OPA), featuring a spectral seamless broadband mid-infrared (MIR) output. By modifying the initial chirp and spectrum of the mode-locked seed laser, the Yb fiber pump laser exhibits a final output power of 14 W with sub-200-fs pulse duration after power amplification and compression. When the OPA was seeded with a broadband amplified spontaneous emission (ASE) source, a damage-limited 0.6 W broadband MIR radiation was experimentally obtained under the pump power of 10.15 W at 82 MHz repetition rate, corresponding to an overall OPA conversion efficiency of 32.7%. The 3 dB bandwidth of the mid-IR idler was 291.9 nm, centering at 3.34 μm. PMID:26670509

  13. High-power femtosecond fiber-feedback optical parametric oscillator based on periodically poled stoichiometric LiTaO3.

    PubMed

    Südmeyer, T; Innerhofer, E; Brunner, F; Paschotta, R; Usami, T; Ito, H; Kurimura, S; Kitamura, K; Hanna, D C; Keller, U

    2004-05-15

    We demonstrate a synchronously pumped high-gain optical parametric oscillator with feedback through a fiber, using a passively mode-locked Yb:YAG thin-disk laser as a pump source. We obtain as much as 19-W average signal power at a wavelength of 1.45 microm in 840-fs pulses and 7.8 W of idler power at 3.57 microm. The repetition rate of the pulses is 56 MHz, and the transverse beam quality of the generated signal is M2 < 1.6. PMID:15182002

  14. High sustained average power cw and ultrafast Yb:YAG near-diffraction-limited cryogenic solid-state laser.

    PubMed

    Brown, David C; Singley, Joseph M; Kowalewski, Katie; Guelzow, James; Vitali, Victoria

    2010-11-22

    We report what we believe to be record performance for a high average power Yb:YAG cryogenic laser system with sustained output power. In a CW oscillator-single-pass amplifier configuration, 963 W of output power was measured. In a second configuration, a two amplifier Yb:YAG cryogenic system was driven with a fiber laser picosecond ultrafast oscillator at a 50 MHz repetition rate, double-passed through the first amplifier and single-passed through the second, resulting in 758 W of average power output. Pulses exiting the system have a FWHM pulsewidth of 12.4 ps, an energy/pulse of 15.2 μJ, and a peak power of 1.23 MW. Both systems are force convection-cooled with liquid nitrogen and have been demonstrated to run reliably over long time periods. PMID:21164825

  15. High-average-power, intense THz pulses from a LiNbO3 slab with silicon output coupler

    NASA Astrophysics Data System (ADS)

    Tsarev, M. V.; Ehberger, D.; Baum, P.

    2016-02-01

    Many applications of THz radiation require high fields and high repetition rates at the same time, implying substantial average power levels. Here, we report high-power Cherenkov-type THz generation in a LiNbO3 slab covered with a silicon prism outcoupler, a geometry in which the ratio between heat-removing surfaces and pump volume is naturally maximized for facilitating heat removal. At a conversion efficiency of 0.04 %, we achieve ~100 times more output power than before with such geometry. Although about 10 % of the 15 W pump power is converted to heat via multi-photon absorption effects, the peak crystal temperature increases by only 8 K. This result is due to the focus' extreme aspect ratio of ~100, indicating the scalability of the approach to even higher average power levels. A line-shaped focus should be advantageous for removing heat in other optical conversions as well.

  16. Ionization-induced effects in the soliton dynamics of high-peak-power femtosecond pulses in hollow photonic-crystal fibers

    SciTech Connect

    Serebryannikov, E. E.; Zheltikov, A. M.

    2007-07-15

    Ionization phenomena are shown to modify the soliton propagation dynamics of high-peak-power laser pulses in hollow-core photonic-crystal fibers (PCFs). Based on the numerical solution of the pulse-evolution equation for a high-peak-power laser field in an ionizing gas medium in a hollow PCF, we demonstrate that hollow PCFs filled with gases having high ionization potentials I{sub p} can support soliton transmission regimes for gigawatt femtosecond laser pulses. In hollow PCFs filled with low-I{sub p} gases, on the other hand, the ionization-induced change in the refractive index of the gas leads to a blueshifting of soliton transients, pushing their spectrum beyond the point of zero group-velocity dispersion, thus preventing the formation of stable high-peak-power solitons.

  17. Spatial distribution of average charge state and deposition rate in high power impulse magnetron sputtering of copper

    SciTech Connect

    Anders, Andre; Horwat, David; Anders, Andre

    2008-05-10

    The spatial distribution of copper ions and atoms in high power impulse magnetron sputtering (HIPIMS) discharges was determined by (i) measuring the ion current to electrostatic probes and (ii) measuring the film thickness by profilometry. A set of electrostatic and collection probes were placed at different angular positions and distances from the target surface. The angular distribution of the deposition rate and the average charge state of the copper species (including ions and neutrals) were deduced.The discharge showed a distinct transition to a high current mode dominated by copper self-sputtering when the applied voltage exceeded the threshold of 535 V. For a lower voltage, the deposition rate was very low and the average charge state was found to be less than 0.4. For higher voltage (and average power), the absolute deposition rates were much higher, but they were smaller than the corresponding direct current (DC) rates if normalized to the same average power. At the high voltage level, the spatial distribution of the average charge state showed some similarities with the distribution of the magnetic field, suggesting that the generation and motion of copper ions is affected by magnetized electrons. At higher voltage, the average charge state increases with the distance from the target and locally may exceed unity, indicating the presence of significant amounts of doubly charged copper ions.

  18. Femtosecond laser ablation properties of transparent materials: impact of the laser process parameters on the machining throughput

    NASA Astrophysics Data System (ADS)

    Matylitsky, V. V.; Hendricks, F.; Aus der Au, J.

    2013-03-01

    High average power, high repetition rate femtosecond lasers with μJ pulse energies are increasingly used for bio-medical and material processing applications. With the introduction of femtosecond laser systems such as the SpiritTM platform developed by High Q Lasers and Spectra-Physics, micro-processing of solid targets with femtosecond laser pulses have obtained new perspectives for industrial applications [1]. The unique advantage of material processing with subpicosecond lasers is efficient, fast and localized energy deposition, which leads to high ablation efficiency and accuracy in nearly all kinds of solid materials. The study on the impact of the laser processing parameters on the removal rate for transparent substrate using femtosecond laser pulses will be presented. In particular, examples of micro-processing of poly-L-lactic acid (PLLA) - bio-degradable polyester and XensationTM glass (Schott) machined with SpiritTM ultrafast laser will be shown.

  19. Alternative lattice options for energy recovery in high-average-power high-efficiency free-electron lasers

    SciTech Connect

    Piot, P.; /Northern Illinois U. /NICADD, DeKalb /Fermilab

    2009-03-01

    High-average-power free-electron lasers often rely on energy-recovering linacs. In a high-efficiency free electron laser, the main limitation to high average power stems from the fractional energy spread induced by the free-electron laser process. Managing beams with large fractional energy spread while simultaneously avoiding beam losses is extremely challenging and relies on intricate longitudinal phase space manipulations. In this paper we discuss a possible alternative technique that makes use of an emittance exchange between one of the transverse and the longitudinal phase spaces.

  20. High average power harmonic mode-locking of a Raman fiber laser based on nonlinear polarization evolution

    NASA Astrophysics Data System (ADS)

    Liu, J.; Zhao, C. J.; Gao, Y. X.; Fan, D. Y.

    2016-03-01

    We experimentally demonstrate the operation of a stable harmonically mode-locked Raman fiber laser based on the nonlinear polarization rotation technique. A maximum average output power of up to 235 mW is achieved at the repetition rate of 466.2 MHz, corresponding to the 1665th order harmonic mode-locking. The temporal width of the mode-locked pulse train is 450 ps. The experimental results should shed some light on the design of wavelength versatile ultrashort lasers with high repetition rate and average output power.

  1. 23-kW peak power femtosecond pulses from a mode-locked fiber ring laser at 2.8 μm

    NASA Astrophysics Data System (ADS)

    Duval, Simon; Olivier, Michel; Fortin, Vincent; Bernier, Martin; Piché, Michel; Vallée, Réal

    2016-03-01

    The recent development of soliton femtosecond fiber lasers emitting at 2.8 μm opens a new avenue for the generation of ultrashort pulses in the mid-infrared spectral region. In this paper, we investigate the peak power scalability of such lasers. By optimizing the output coupling ratio and the length of the Er3+: fluoride fiber in the cavity, we demonstrate the generation of 270-fs pulses with an energy of 7 nJ and an estimated peak power of 23 kW. These record performances at 2.8 μm surpass by far those obtained from standard soliton lasers at 1.55 μm. A numerical model of the laser including the effect of the intracavity atmospheric absorption is also presented. Numerical simulations agree well with the experimental results and suggest that the atmospheric propagation in the cavity could prevent the laser from self-starting in a mode-locked regime. This femtosecond laser could be the building block for simple and compact mid-infrared frequency combs and supercontinuum sources.

  2. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed. PMID:27472594

  3. Efficient processing of CFRP with a picosecond laser with up to 1.4 kW average power

    NASA Astrophysics Data System (ADS)

    Onuseit, V.; Freitag, C.; Wiedenmann, M.; Weber, R.; Negel, J.-P.; Löscher, A.; Abdou Ahmed, M.; Graf, T.

    2015-03-01

    Laser processing of carbon fiber reinforce plastic (CFRP) is a very promising method to solve a lot of the challenges for large-volume production of lightweight constructions in automotive and airplane industries. However, the laser process is actual limited by two main issues. First the quality might be reduced due to thermal damage and second the high process energy needed for sublimation of the carbon fibers requires laser sources with high average power for productive processing. To achieve thermal damage of the CFRP of less than 10μm intensities above 108 W/cm² are needed. To reach these high intensities in the processing area ultra-short pulse laser systems are favored. Unfortunately the average power of commercially available laser systems is up to now in the range of several tens to a few hundred Watt. To sublimate the carbon fibers a large volume specific enthalpy of 85 J/mm³ is necessary. This means for example that cutting of 2 mm thick material with a kerf width of 0.2 mm with industry-typical 100 mm/sec requires several kilowatts of average power. At the IFSW a thin-disk multipass amplifier yielding a maximum average output power of 1100 W (300 kHz, 8 ps, 3.7 mJ) allowed for the first time to process CFRP at this average power and pulse energy level with picosecond pulse duration. With this unique laser system cutting of CFRP with a thickness of 2 mm an effective average cutting speed of 150 mm/sec with a thermal damage below 10μm was demonstrated.

  4. Femtosecond Laser--Pumped Source of Entangled Photons for Quantum Cryptography Applications

    SciTech Connect

    Pan, D.; Donaldson, W.; Sobolewski, R.

    2007-07-31

    We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion, based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulse-width, mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an equal pump power. The resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes. Our apparatus is intended as an efficient source/receiver system for the quantum communications and quantum cryptography applications.

  5. A Code to Produce Cell Averaged Cross Sections for Fast Critical Assemblies and Fast Power Reactors.

    Energy Science and Technology Software Center (ESTSC)

    1987-05-14

    Version 00 SLAROM solves the neutron integral transport equations to determine the flux distribution and spectra in a fast reactor lattice and calculates cell averaged effective cross sections. The code uses multigroup data of the type in DLC-111/JFS that use Bondarenko factors for resonance effects.

  6. 200W average power 1mJ pulse energy from spectrally combined pulsed sub-5 ns fiber laser source

    NASA Astrophysics Data System (ADS)

    Schmidt, O.; Ortac, B.; Limpert, J.; Tünnermann, A.; Andersen, Thomas V.

    2009-02-01

    In this contribution, we report on spectral combination of four sub-5ns pulsed fiber amplifier systems with an average output power of 200W at 200kHz repetition rate resulting in 1mJ of pulse energy. A dielectric reflection grating is used to combine four individual beams to one output possessing a measured M2 value of 1.3 and 1.8, respectively, independent of power level. Extraction of higher pulse energies and peak powers will be discussed.

  7. Electron-beam and high-speed optical diagnostics for the average power laser experiment (APLE) program

    NASA Astrophysics Data System (ADS)

    Lumpkin, Alex H.; McVey, Brian D.; Greegor, Robert B.; Dowell, David H.

    1992-07-01

    The average power laser experiment (APLE) program is a collaboration between Boeing Aerospace and Electronics Company and Los Alamos National Laboratory to build a free-electron laser (FEL) operating at a wavelength of 10 μm and an average power of 100 kW. This program includes demonstration experiments at Boeing on the injector and at Los Alamos on a single accelerator master oscillator power amplifier (SAMOPA). In response to simulations of the expected electron beam properties, diagnostic plans have been developed for the low duty factor and the 25% duty factor operations of APLE. Preliminary evaluations of diagnostics based on information conversion to visible or near-infrared light (optical-transition radiation, Cherenkov radiation, synchrotron radiation, and spontaneous-emission radiation) or electrical signals (striplines, toroids, flying wires, etc.) are addressed.

  8. Self-starting passively mode-locked tunable femtosecond Cr 4+:YAG laser using a saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Hayduk, M. J.; Johns, S. T.; Krol, M. F.; Pollock, C. R.; Leavitt, R. P.

    1997-02-01

    We have demonstrated self-starting, passive mode-locking of a Cr 4+:YAG laser using a saturable absorber mirror structure. Highly stable femtosecond pulses tunable from 1488 to 1535 nm were generated with average output powers ranging from 40 to 80 mW. Nearly transform limited pulses of 120 fs duration were obtained at 1488 nm.

  9. Different cooling configurations for a high average power longitudinally diode-pumped Yb:YAG amplifier.

    PubMed

    Yu, Haiwu; Bourdet, Gilbert

    2006-08-20

    We analyze the temperature distribution in several Yb:YAG longitudinally pumped amplifier crystals by using various cooling configurations. The crystal designs are (i) a composite crystal made of a thin sheet of high-doped Yb:YAG bonded on a bulk piece of undoped YAG and (ii) a thick piece of low-doped Yb:YAG crystal. The cooling configurations investigated here include those both from the rear face or from the rear and side faces together. In every case we determine the average temperature rise, the longitudinal and radial temperature gradient, and the resulting crystal bending and optical phase distortion. We optimize the best cooling configuration and crystal design by compromising the average temperature, thermodeformation, and optical phase distortion. The experimental results also indicate that a thin sheet of gain medium (1.6 mm thick at 10 at. % doping) suffers from a notable bending deformation, which results in an unexpected decrease of the output energy. PMID:16892125

  10. Multipulse operation of a high average power, good beam quality zig-zag dye laser

    SciTech Connect

    Mandl, A.; Klimek, D.E.

    1996-03-01

    A laser pumped zig-zag dye laser operating at 568 nm with a pulse length {approximately} 2 {micro}s has been scaled to high power using a MOPA configuration. Pulse energies in excess of 7 J with beam quality < 2 XDL have been achieved under repetitively pulsed, 10 Hz operation. RMS jitter was measured as 0.12 of a 1 XDL spot. The device has operated with over 70 W output for runs up to 5 s. Substantially longer run times and output powers are possible. This device represents an advance in dye laser capabilities. Improvement in pointing accuracy of better than an order of magnitude have been demonstrated. In addition, an improvement in beam quality by about an order of magnitude has been achieved compared to other dye lasers operating in this power range.

  11. Simulations of the high average power selene free electron laser prototype. Master's thesis

    SciTech Connect

    Quick, D.D.

    1994-06-01

    Free electron laser (FEL) technology continues to advance, providing alternative solutions to existing and potential problems. The capabilities of an FEL with respect to tunability, power and efficiency make it an attractive choice when moving into new laser utilization fields. The initial design parameters, for any new system, offer a good base to begin system simulation tests in an effort to determine the best possible design. This is a study of the Novosibirsk design which is a prototype for the proposed SELENE FEL. The design uses a three-section, low-power optical klystron followed by a single-pass, high-power radiator. This system is inherently sensitive to electron beam quality, but affords flexibility in achieving the final design. The performance of the system is studied using the initial parameters. An FEL, configured as a simple, two section optical klystron is studied to determine the basic operating characteristics of a high current FEL klystron.

  12. Integrated Tm:fiber MOPA with polarized output and narrow linewidth with 100 W average power.

    PubMed

    Shah, Lawrence; Sims, R Andrew; Kadwani, Pankaj; Willis, Christina C C; Bradford, Joshua B; Pung, Aaron; Poutous, Menelaos K; Johnson, Eric G; Richardson, Martin

    2012-08-27

    We report on a Tm:fiber master oscillator power amplifier (MOPA) system producing 109 W CW output power, with >15 dB polarization extinction ratio, sub-nm spectral linewidth, and M2 <1.25. The system consists of polarization maintaining (PM) fiber and PM-fiber components including tapered fiber bundle pump combiners, a single-mode to large mode area mode field adapter, and a fiber-coupled isolator. The laser components ultimately determine the system architecture and the limits of laser performance, particularly considering the immature and rapidly developing state of fiber components in the 2 μm wavelength regime. PMID:23037103

  13. Does Stevens's Power Law for Brightness Extend to Perceptual Brightness Averaging?

    ERIC Educational Resources Information Center

    Bauer, Ben

    2009-01-01

    Stevens's power law ([Psi][infinity][Phi][beta]) captures the relationship between physical ([Phi]) and perceived ([Psi]) magnitude for many stimulus continua (e.g., luminance and brightness, weight and heaviness, area and size). The exponent ([beta]) indicates whether perceptual magnitude grows more slowly than physical magnitude ([beta] less…

  14. Error analysis in the measurement of average power with application to switching controllers

    NASA Technical Reports Server (NTRS)

    Maisel, J. E.

    1979-01-01

    The behavior of the power measurement error due to the frequency responses of first order transfer functions between the input sinusoidal voltage, input sinusoidal current and the signal multiplier was studied. It was concluded that this measurement error can be minimized if the frequency responses of the first order transfer functions are identical.

  15. Generation of high-power femtosecond supercontinua in the near-IR spectral range using broadband parametric frequency conversion in LBO and DCDA crystals pumped at λ = 620 nm

    SciTech Connect

    Podshivalov, A A; Sidorov-Biryukov, D A; Potemkin, F V

    2014-09-30

    The pump wavelength of parametric amplifiers based on CLBO, DCDA and LBO crystals and pumped by the second harmonic of a femtosecond Cr : forsterite laser (620 nm) is close to optimal for broadband amplification because of the proximity of group velocities of interacting pulses. Injection of a broadband continuum into the range of the signal-wave gain in LBO and DCDA parametric amplifiers, pumped at λ = 620 nm, leads to generation of broadband femtosecond pulses with a spectrum ranging from 1050 to 1600 nm and peak powers up to 20 MW. (nonlinear optical phenomena)

  16. Generation of high-power femtosecond supercontinua in the near-IR spectral range using broadband parametric frequency conversion in LBO and DCDA crystals pumped at λ = 620 nm

    NASA Astrophysics Data System (ADS)

    Podshivalov, A. A.; Potemkin, F. V.; Sidorov-Biryukov, D. A.

    2014-09-01

    The pump wavelength of parametric amplifiers based on CLBO, DCDA and LBO crystals and pumped by the second harmonic of a femtosecond Cr : forsterite laser (620 nm) is close to optimal for broadband amplification because of the proximity of group velocities of interacting pulses. Injection of a broadband continuum into the range of the signal-wave gain in LBO and DCDA parametric amplifiers, pumped at λ = 620 nm, leads to generation of broadband femtosecond pulses with a spectrum ranging from 1050 to 1600 nm and peak powers up to 20 MW.

  17. High-average-power diode-end-pumped intracavity-doubled Nd:YAG laser

    SciTech Connect

    Honea, E.C.; Ebbers, C.A.; Beach, R.J.; Speth, J.A.; Emanuel, M.S>; Skidmore, J.A.; Payne, S.A.

    1998-02-12

    A compact diode-pumped ND:YAG laser was frequency-doubled to 0.532 {mu}m with an intracavity KTP or LBO crystal using a `V` cavity configuration. Two acousto-optic Q-switches were employed at repetition rates of 10-30 kHz. Dichroic fold and end mirrors were used to output two beams with up to 140 W of 0.532 {mu}m power using KTP and 116 W using LBO as the frequency doubling crystal. This corresponds to 66% of the maximum output power at 1.064 {mu}m obtained with an optimized output coupler reflectivity. The minimum output pulse duration varied with repetition rate from 90 to 130 ns. The multimode output beam had a smooth profile and a beam quality of M{sup 2} = 5 1.

  18. Program THEK energy production units of average power and using thermal conversion of solar radiation

    NASA Technical Reports Server (NTRS)

    1978-01-01

    General studies undertaken by the C.N.R.S. in the field of solar power plants have generated the problem of building energy production units in the medium range of electrical power, in the order of 100 kW. Among the possible solutions, the principle of the use of distributed heliothermal converters has been selected as being, with the current status of things, the most advantageous solution. This principle consists of obtaining the conversion of concentrated radiation into heat by using a series of heliothermal conversion modules scattered over the ground; the produced heat is collected by a heat-carrying fluid circulating inside a thermal loop leading to a device for both regulation and storage.

  19. High-Efficiency 800 nm Multi-Layer Dielectric Gratings for High Average Power Laser Systems

    SciTech Connect

    Nguyen, H T; Britten, J A; Patel, D; Brizuela, F; Rocca, J J; Menoni, C S

    2006-06-15

    We report on the design, fabrication, and performance of a 1740 l/mm multilayer dielectric diffraction grating for use with 800 nm light. At an input angle of 8{sup o} from Littrow and a wavelength from 770 to 830 nm, >90% diffraction efficiency is achieved, with peak diffraction efficiency of >97% at 800nm. We will also comment on laser damage threshold and power-handling properties.

  20. SM green fiber laser operating in CW and QCW regimes and producing over 550W of average output power

    NASA Astrophysics Data System (ADS)

    Gapontsev, Valentin; Avdokhin, Alexey; Kadwani, Pankaj; Samartsev, Igor; Platonov, Nikolai; Yagodkin, Roman

    2014-02-01

    We report a single-mode (SM) green laser based on single-pass frequency doubling of a linearly-polarized narrowlinewidth Yb fiber laser in LBO crystal, and configured to operate in a range of regimes from continuous-wave (CW) to high-repetition-rate quasi-continuous-wave (QCW). Adjusting the duty cycle, we maintained high second harmonic generation (SHG) efficiency for various output powers. Average powers of over 550W in QCW and over 350W in CW regimes were obtained with the wall-plug efficiency up to 15%, opening the possibility to creating new class of simple, compact and efficient single-mode green lasers with output power up to 1kW and above. The same approach could also be used to create high-power lasers operating at other wavelengths in ultraviolet and visible spectral ranges.

  1. Mode-locked Yb:YAG thin-disk oscillator with 41 µJ pulse energy at 145 W average infrared power and high power frequency conversion.

    PubMed

    Bauer, Dominik; Zawischa, Ivo; Sutter, Dirk H; Killi, Alexander; Dekorsy, Thomas

    2012-04-23

    We demonstrate the generation of 1.1 ps pulses containing more than 41 µJ of energy directly out of an Yb:YAG thin-disk without any additional amplification stages. The laser oscillator operates in ambient atmosphere with a 3.5 MHz repetition rate and 145 W of average output power at a fundamental wavelength of 1030 nm. An average output power of 91.5 W at 515 nm was obtained by frequency doubling with a conversion efficiency exceeding 65%. Third harmonic generation resulted in 34 W at 343 nm at 34% efficiency. PMID:22535061

  2. 60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser.

    PubMed

    Innerhofer, E; Südmeyer, T; Brunner, F; Häring, R; Aschwanden, A; Paschotta, R; Hönninger, C; Kumkar, M; Keller, U

    2003-03-01

    We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 microJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M2 < 1.1. PMID:12659446

  3. High energy, high average power solid state green or UV laser

    DOEpatents

    Hackel, Lloyd A.; Norton, Mary; Dane, C. Brent

    2004-03-02

    A system for producing a green or UV output beam for illuminating a large area with relatively high beam fluence. A Nd:glass laser produces a near-infrared output by means of an oscillator that generates a high quality but low power output and then multi-pass through and amplification in a zig-zag slab amplifier and wavefront correction in a phase conjugator at the midway point of the multi-pass amplification. The green or UV output is generated by means of conversion crystals that follow final propagation through the zig-zag slab amplifier.

  4. SBS of repetitively pulsed radiation and possibility of increasing of the pump average power

    SciTech Connect

    Andreev, N.; Kulagin, O.; Palashov, O.; Pasmanik, G.; Rodchenkov, V.

    1995-12-31

    The features of liquid purification from molecular and dispersive admixtures are studied. The analysis has revealed the processes (thermal effects, microparticles heating with a subsequent optical breakdown, Stimulated Raman Scattering) limiting pumping pulse energy. These effects complicate also a realization of a high quality phase conjugation at SBS. The data concerning physical properties of liquid tetrachlorides and freons are presented. The picture of a behavior of liquid under conditions of an optical breakdown is described. Some recommendations regarding a choice of nonlinear media are formulated. The two-cell scheme providing a phase conjugation of powerful short laser pulses is proposed. This is important in the field of inertial confinement fusion.

  5. Edge-facet pumped, multi-aperture, thin-disk laser geometry for very high average power output scaling

    DOEpatents

    Zapata, Luis E.

    2004-12-21

    The average power output of a laser is scaled, to first order, by increasing the transverse dimension of the gain medium while increasing the thickness of an index matched light guide proportionately. Strategic facets cut at the edges of the laminated gain medium provide a method by which the pump light introduced through edges of the composite structure is trapped and passes through the gain medium repeatedly. Spontaneous emission escapes the laser volume via these facets. A multi-faceted disk geometry with grooves cut into the thickness of the gain medium is optimized to passively reject spontaneous emission generated within the laser material, which would otherwise be trapped and amplified within the high index composite disk. Such geometry allows the useful size of the laser aperture to be increased, enabling the average laser output power to be scaled.

  6. Non-Invasive Beam Detection in a High-Average Power Electron Accelerator

    SciTech Connect

    Williams, J.; Biedron, S.; Harris, J.; Martinez, J.; Milton, S. V.; Van Keuren, J.; Benson, Steve V.; Evtushenko, Pavel; Neil, George R.; Zhang, Shukui

    2013-12-01

    For a free-electron laser (FEL) to work effectively the electron beam quality must meet exceptional standards. In the case of an FEL operating at infrared wavelengths in an amplifier configuration the critical phase space tends to be in the longitudinal direction. Achieving high enough longitudinal phase space density directly from the electron injector system of such an FEL is difficult due to space charge effects, thus one needs to manipulate the longitudinal phase space once the beam energy reaches a sufficiently high value. However, this is fraught with problems. Longitudinal space charge and coherent synchrotron radiation can both disrupt the overall phase space, furthermore, the phase space disruption is exacerbated by the longitudinal phase space manipulation process required to achieve high peak current. To achieve and maintain good FEL performance one needs to investigate the longitudinal emittance and be able to measure it during operation preferably in a non-invasive manner. Using the electro-optical sampling (EOS) method, we plan to measure the bunch longitudinal profile of a high-energy (~120-MeV), high-power (~10kW or more FEL output power) beam.

  7. Brightness and average power as driver for advancements in diode lasers and their applications

    NASA Astrophysics Data System (ADS)

    Hengesbach, Stefan; Poprawe, Reinhart; Hoffmann, Dieter; Traub, Martin; Schwarz, Thomas; Holly, Carlo; Eibl, Florian; Weisheit, Andreas; Vogt, Sabrina; Britten, Simon; Ungers, Michael; Thombansen, Ulrich; Engelmann, Christoph; Mamuschkin, Viktor; Lott, Philipp

    2015-03-01

    Spatial and spectral emission characteristics and efficiency of high-power diode laser (HPDL) based pump sources enable and define the performance of the fundamental solid state laser concepts like disk, fiber and slab lasers. HPDL are also established as a versatile tool for direct materials processing substituting other laser types like CO2 lasers and lamp pumped solid state lasers and are starting to substitute even some of the diode pumped solid state lasers. Both, pumping and direct applications will benefit from the further improvement of the brightness and control of the output spectrum of HPDL. While edge emitting diodes are already established, a new generation of vertical emitting diode lasers (VCSELs) made significant progress and provides easy scalable output power in the kW range. Beneficial properties are simplified beam shaping, flexible control of the temporal and spatial emission, compact design and low current operation. Other characteristics like efficiency and brightness of VCSELs are still lagging behind the edge emitter performance. Examples of direct applications like surface treatment, soldering, welding, additive manufacturing, cutting and their requirements on the HPDL performance are presented. Furthermore, an overview on process requirements and available as well as perspective performance of laser sources is derived.

  8. Power- and polarization-dependent supercontinuum generation in α -BaB2O4 crystals by intense, near-infrared, femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Vasa, Parinda; Dota, Krithika; Singh, Mamraj; Kushavah, Dushyant; Singh, Bhanu P.; Mathur, Deepak

    2015-05-01

    We report generation of a broadband supercontinuum (SC) in a birefringent crystal upon irradiation by intense, near-infrared, femtosecond laser pulses and investigate its dependence on incident laser power and the initial laser polarization. We choose as our sample α -BaB2O4 (α -BBO), a material in which the third order is the lowest order of nonvanishing nonlinear optical susceptibility. Three different SC generation mechanisms are identified under our experimental conditions; these are found to depend upon the pump power Pp u. Close to the critical power for self-focusing (Pp u˜5 MW), the spectrum is dominated by Kerr nonlinearity or self-phase modulation, whereas at intermediate pumping Pp u˜125 MW, Raman amplification on the Stokes side is a dominating mechanism. At higher pump power ˜300 MW, significant asymmetric broadening extending up to ˜570 nm is observed due to the coherent anti-Stokes Raman scattering. Our study provides an intuitive explanation for the observed power- and polarization-dependent SC generation in α -BBO crystals.

  9. High-average-power, 100-Hz-repetition-rate, tabletop soft-x-ray lasers at sub-15-nm wavelengths

    NASA Astrophysics Data System (ADS)

    Reagan, Brendan A.; Berrill, Mark; Wernsing, Keith A.; Baumgarten, Cory; Woolston, Mark; Rocca, Jorge J.

    2014-05-01

    Efficient excitation of dense plasma columns at 100-Hz repetition rate using a tailored pump pulse profile produced a tabletop soft-x-ray laser average power of 0.1 mW at λ = 13.9 nm and 20 μW at λ = 11.9 nm from transitions of Ni-like Ag and Ni-like Sn, respectively. Lasing on several other transitions with wavelengths between 10.9 and 14.7 nm was also obtained using 0.9-J pump pulses of 5-ps duration from a compact diode-pumped chirped pulse amplification Yb:YAG laser. Hydrodynamic and atomic plasma simulations show that the pump pulse profile, consisting of a nanosecond ramp followed by two peaks of picosecond duration, creates a plasma with an increased density of Ni-like ions at the time of peak temperature that results in a larger gain coefficient over a temporally and spatially enlarged space leading to a threefold increase in the soft-x-ray laser output pulse energy. The high average power of these compact soft-x-ray lasers will enable applications requiring high photon flux. These results open the path to milliwatt-average-power tabletop soft-x-ray lasers.

  10. Thin-disk multipass amplifier for ultrashort laser pulses with kilowatt average output power and mJ pulse energies

    NASA Astrophysics Data System (ADS)

    Negel, Jan-Philipp; Voss, Andreas; Abdou Ahmed, Marwan; Bauer, Dominik; Sutter, Dirk; Killi, Alexander; Graf, Thomas

    2014-05-01

    We report on a Yb:YAG thin-disk multipass amplifier for ultrashort laser pulses delivering an average output power of 1.1 kW which to the best of our knowledge is the highest output power reported from such a system so far. A modified commercial TruMicro5050 laser delivers the seed pulses with an average power of 80 W at a wavelength of 1030 nm, a pulse duration of 6.5 ps and a repetition rate of 800 kHz. These pulses are amplified to 1.38 mJ of pulse energy with a duration of 7.3 ps. To achieve this, we developed a scheme in which an array of 40 plane mirrors is used to geometrically fold the seed beam over the pumped thin-disk crystal. Exploiting the incoming linear polarization, an overall number of 40 double-passes through the disk was realized by using the backpath through the amplifier with the orthogonal linear polarization state. Thermal issues on the disk were mitigated by zero-phonon line pumping at a wavelength of 969 nm directly into the upper laser level and by employing a retroreflective mirror pair. The amplifier exhibits an optical efficiency of 44 % and a slope efficiency of 46 %. The beam quality was measured to be better than M2=1.25 at all power levels. As this system can deliver high pulse energies and high average output powers at the same time without the need of a CPA technique, it can be very suitable for high productivity material processing with ultrashort laser pulses.

  11. Simulation of a high-average power free-electron laser oscillator

    SciTech Connect

    H.P. Freund; M. Shinn; S.V. Benson

    2007-03-01

    In this paper, we compare the 10 kW-Upgrade experiment at the Thomas Jefferson National Accelerator Facility in Newport News, VA, with numerical simulations using the medusa code. medusa is a three-dimensional FEL simulation code that is capable of treating both amplifiers and oscillators in both the steady-state and time-dependent regimes. medusa employs a Gaussian modal expansion, and treats oscillators by decomposing the modal representation at the exit of the wiggler into the vacuum Gaussian modes of the resonator and then analytically determining the propagation of these vacuum resonator modes through the resonator back to the entrance of the wiggler in synchronism with the next electron bunch. The bunch length in the experiment is of the order of 380–420 fsec FWHM. The experiment operates at a wavelength of about 1.6 microns and the wiggler is 30 periods in length; hence, the slippage time is about 160 fsec. Because of this, slippage is important, and must be included in the simulation. The observed single pass gain is 65%–75% and, given the experimental uncertainties, this is in good agreement with the simulation. Multipass simulations including the cavity detuning yield an output power of 12.4 kW, which is also in good agreement with the experiment.

  12. 250 W average power, 100 kHz repetition rate cryogenic Yb:YAG amplifier for OPCPA pumping.

    PubMed

    Zapata, L E; Reichert, F; Hemmer, M; Kärtner, F X

    2016-02-01

    A cryogenically cooled, bulk Yb:YAG, four-pass amplifier delivering up to 250 W average power at 100 kHz repetition rate is reported. The 2.5 mJ amplified optical pulses show a sub-20 ps duration before temporal compression and a spectrum supporting a transform-limited duration of 3.6 ps. The power instabilities were measured to be <0.5% rms over 30 min at full power, and the spatial intensity profile showed a flat-top distribution and near diffraction-limited beam quality. This compact amplifier is an ideal source for pumping either near-IR or mid-IR optical parametric chirped pulse amplifiers. PMID:26907405

  13. Yb-fiber-laser-based, 1.8 W average power, picosecond ultraviolet source at 266 nm.

    PubMed

    Chaitanya Kumar, S; Canals Casals, J; Sanchez Bautista, E; Devi, K; Ebrahim-Zadeh, M

    2015-05-15

    We report a compact, stable, high-power, picosecond ultraviolet (UV) source at 266 nm based on simple single-pass two-step fourth-harmonic generation (FHG) of a mode-locked Yb-fiber laser at 79.5 MHz in LiB3O5 (LBO) and β-BaB2O4. Using a 30-mm-long LBO crystal for single-pass second-harmonic generation, we achieve up to 9.1 W of average green power at 532 nm for 16.8 W of Yb-fiber power at a conversion efficiency of 54% in 16.2 ps pulses with a TEM00 spatial profile and passive power stability better than 0.5% rms over 16 h. The generated green radiation is then used for single-pass FHG into the UV, providing as much as 1.8 W of average power at 266 nm under the optimum focusing condition in the presence of spatial walk-off, at an overall FHG conversion efficiency of ∼11%. The generated UV output exhibits passive power stability better than 4.6% rms over 1.5 h and beam pointing stability better than 84 μrad over 1 h. The UV output beam has a circularity of >80% in high beam quality with the TEM00 mode profile. To the best of our knowledge, this is the first report of picosecond UV generation at 266 nm at megahertz repetition rates. PMID:26393749

  14. The Mercury Laser System-A scaleable average-power laser for fusion and beyond

    SciTech Connect

    Ebbers, C A; Moses, E I

    2008-03-26

    Nestled in a valley between the whitecaps of the Pacific and the snowcapped crests of the Sierra Nevada, Lawrence Livermore National Laboratory (LLNL) is home to the nearly complete National Ignition Facility (NIF). The purpose of NIF is to create a miniature star-on demand. An enormous amount of laser light energy (1.8 MJ in a pulse that is 20 ns in duration) will be focused into a small gold cylinder approximately the size of a pencil eraser. Centered in the gold cylinder (or hohlraum) will be a nearly perfect sphere filled with a complex mixture of hydrogen gas isotopes that is similar to the atmosphere of our Sun. During experiments, the laser light will hit the inside of the gold cylinder, heating the metal until it emits X-rays (similar to how your electric stove coil emits visible red light when heated). The X-rays will be used to compress the hydrogen-like gas with such pressure that the gas atoms will combine or 'fuse' together, producing the next heavier element (helium) and releasing energy in the form of energetic particles. 2010 will mark the first credible attempt at this world-changing event: the achievement of fusion energy 'break-even' on Earth using NIF, the world's largest laser! NIF is anticipated to eventually perform this immense technological accomplishment once per week, with the capability of firing up to six shots per day - eliminating the need for continued underground testing of our nation's nuclear stockpile, in addition to opening up new realms of science. But what about the day after NIF achieves ignition? Although NIF will achieve fusion energy break-even and gain, the facility is not designed to harness the enormous potential of fusion for energy generation. A fusion power plant, as opposed to a world-class engineering research facility, would require that the laser deliver drive pulses nearly 100,000 times more frequently - a rate closer to 10 shots per second as opposed to several shots per day.

  15. High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Liangliang; Mu, Kaijun; Zhou, Yunsong; Wang, Hai; Zhang, Cunlin; Zhang, X.-C.

    2015-07-01

    Terahertz (THz) spectroscopic sensing and imaging has identified its potentials in a number of areas such as standoff security screening at portals, explosive detection at battle fields, bio-medical research, and so on. With these needs, the development of an intense and broadband THz source has been a focus of THz research. In this work, we report an intense (~10 mW) and ultra-broadband (~150 THz) THz to infrared (IR) source with a Gaussian wavefront, emitted from nano-pore-structured metallic thin films with femtosecond laser pulse excitation. The underlying mechanism has been proposed as thermal radiation. In addition, an intense coherent THz signal was generated through the optical rectification process simultaneously with the strong thermal signal. This unique feature opens up new avenues in biomedical research.

  16. High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

    PubMed Central

    Zhang, Liangliang; Mu, Kaijun; Zhou, Yunsong; Wang, Hai; Zhang, Cunlin; Zhang, X.-C.

    2015-01-01

    Terahertz (THz) spectroscopic sensing and imaging has identified its potentials in a number of areas such as standoff security screening at portals, explosive detection at battle fields, bio-medical research, and so on. With these needs, the development of an intense and broadband THz source has been a focus of THz research. In this work, we report an intense (~10 mW) and ultra-broadband (~150 THz) THz to infrared (IR) source with a Gaussian wavefront, emitted from nano-pore-structured metallic thin films with femtosecond laser pulse excitation. The underlying mechanism has been proposed as thermal radiation. In addition, an intense coherent THz signal was generated through the optical rectification process simultaneously with the strong thermal signal. This unique feature opens up new avenues in biomedical research. PMID:26205611

  17. High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures.

    PubMed

    Zhang, Liangliang; Mu, Kaijun; Zhou, Yunsong; Wang, Hai; Zhang, Cunlin; Zhang, X-C

    2015-01-01

    Terahertz (THz) spectroscopic sensing and imaging has identified its potentials in a number of areas such as standoff security screening at portals, explosive detection at battle fields, bio-medical research, and so on. With these needs, the development of an intense and broadband THz source has been a focus of THz research. In this work, we report an intense (~10 mW) and ultra-broadband (~150 THz) THz to infrared (IR) source with a Gaussian wavefront, emitted from nano-pore-structured metallic thin films with femtosecond laser pulse excitation. The underlying mechanism has been proposed as thermal radiation. In addition, an intense coherent THz signal was generated through the optical rectification process simultaneously with the strong thermal signal. This unique feature opens up new avenues in biomedical research. PMID:26205611

  18. Optimal dynamic vibration absorber design for minimizing the band-averaged input power using the residue theorem

    NASA Astrophysics Data System (ADS)

    D`Amico, R.; Koo, K.; Claeys, C. C.; Pluymers, B.; Desmet, W.

    2015-03-01

    This paper deals with an efficient strategy to improve the vibro-acoustic behavior of a structure over frequency bands. Genetic Algorithms are used to identify the optimal resonance frequency and location of Dynamic Vibration Absorbers (DVAs) which minimize the band-averaged input power into a plate, leading to an indirect reduction of the radiated acoustic power and global vibration. Instead of classic numerical quadrature schemes, the residue theorem is used to evaluate the band-averaged input power. This results into a considerable reduction of computational effort, as it requires only few function evaluations at complex frequencies, regardless of the analyzed bandwidth. The structural response is simulated by using the Wave Based Method (WBM). Besides an increased convergence rate as compared to classical element-based techniques, the WBM is also free in determining the optimal position of the DVAs, not restricting it to nodal grid locations. Moreover, when point connections are taken into account, only a small part of the WB matrices needs to be recomputed at each iteration, resulting in a strong reduction of the computation time. Numerical examples illustrate the benefits and the efficiency of the proposed optimization strategy.

  19. In-situ optical phase distortion measurement of Yb:YAG thin disk in high average power regenerative amplifier

    NASA Astrophysics Data System (ADS)

    Miura, Taisuke; Chyla, Michal; Smrž, Martin; Nagisetty, Siva Sankar; Severová, Patricie; Novák, Ondřej; Endo, Akira; Mocek, TomáÅ.¡

    2013-02-01

    We are developing one kilohertz picosecond Yb:YAG thin disk regenerative amplifier with 500-W average power for medical and industrial applications. In case of high energy pulse amplification, a large area mode matching in gain media, which is drastically degenerated by the optical phase distortion, is required to avoid optical damage. We designed in-situ thin disk deformation measurement based on the combination of a precise wavefront sensor and a single mode probe beam. In contrast to a conventional interferometric measurement, this measurement is compact, easy-to-align, and is less affected by mechanical vibrations.

  20. 3 GHz, watt-level femtosecond Raman soliton source.

    PubMed

    Lim, Jinkang; Chen, Hung-Wen; Xu, Shanhui; Yang, Zhongmin; Chang, Guoqing; Kärtner, Franz X

    2014-04-01

    We demonstrate a 3 GHz repetition rate, femtosecond Raman soliton source with its wavelength tunable from 1.15 to 1.35 μm. We investigate the dependence of Raman soliton formation on different photonic-crystal fibers (PCFs), input powers, and fiber lengths. To produce a Raman soliton peaking at the same wavelength, shorter PCFs demand higher input average powers and consequently generate stronger Raman soliton pulses. Using 30 cm PCF NL-3.2-945, the resulting Raman soliton pulse at 1.35 μm has 0.9 W average power. The integrated relative intensity noise of the Raman soliton pulse at 1.35 μm generated from the 54-cm PCF NL-3.2-945 is as low as 0.33% from 100 Hz to 10 MHz. PMID:24686674

  1. Peak-to-Average-Power-Ratio (PAPR) reduction in WiMAX and OFDM/A systems

    NASA Astrophysics Data System (ADS)

    Khademi, Seyran; Svantesson, Thomas; Viberg, Mats; Eriksson, Thomas

    2011-12-01

    A peak to average power ratio (PAPR) reduction method is proposed that exploits the precoding or beamforming mode in WiMAX. The method is applicable to any OFDM/A systems that implements beamforming using dedicated pilots which use the same beamforming antenna weights for both pilots and data. Beamforming performance depends on the relative phase shift between antennas, but is unaffected by a phase shift common to all antennas. PAPR, on the other hand, changes with a common phase shift and this paper exploits that property. An effective optimization technique based on sequential quadratic programming is proposed to compute the common phase shift. The proposed technique has several advantages compared with traditional PAPR reduction techniques in that it does not require any side-information and has no effect on power and bit-error-rate while providing better PAPR reduction performance than most other methods.

  2. Actively mode-locked Tm(3+)-doped silica fiber laser with wavelength-tunable, high average output power.

    PubMed

    Kneis, Christian; Donelan, Brenda; Berrou, Antoine; Manek-Hönninger, Inka; Robin, Thierry; Cadier, Benoît; Eichhorn, Marc; Kieleck, Christelle

    2015-04-01

    A diode-pumped, actively mode-locked high-power thulium (Tm3+)-doped double-clad silica fiber laser is demonstrated, providing an average output power in mode-locked (continuous wave) operation of 53 W (72 W) with a slope efficiency of 34% (38%). Mode-locking in the 6th-harmonic order was obtained by an acousto-optic modulator driven at 66 MHz without dispersion compensation. The shortest measured output pulse width was 200 ps. Owing to a diffraction grating as cavity end mirror, the central wavelength could be tuned from 1.95 to 2.13 μm. The measured beam quality in mode-locked and continuous wave operation has been close to the diffraction limit. PMID:25831360

  3. All solid-state spectral broadening: an average and peak power scalable method for compression of ultrashort pulses.

    PubMed

    Seidel, Marcus; Arisholm, Gunnar; Brons, Jonathan; Pervak, Vladimir; Pronin, Oleg

    2016-05-01

    Spectral broadening in bulk material is a simple, robust and low-cost method to extend the bandwidth of a laser source. Consequently, it enables ultrashort pulse compression. Experiments with a 38 MHz repetition rate, 50 W average power Kerr-lens mode-locked thin-disk oscillator were performed. The initially 1.2 μJ, 250 fs pulses are compressed to 43 fs by means of self-phase modulation in a single 15 mm thick quartz crystal and subsequent chirped-mirror compression. The losses due to spatial nonlinear effects are only about 40 %. A second broadening stage reduced the Fourier transform limit to 15 fs. It is shown that the intensity noise of the oscillator is preserved independent of the broadening factor. Simulations manifest the peak power scalability of the concept and show that it is applicable to a wide range of input pulse durations and energies. PMID:27137557

  4. Long distance measurement with femtosecond pulses using a dispersive interferometer.

    PubMed

    Cui, M; Zeitouny, M G; Bhattacharya, N; van den Berg, S A; Urbach, H P

    2011-03-28

    We experimentally demonstrate long distance measurements with a femtosecond frequency comb laser using dispersive interferometry. The distance is derived from the unwrapped spectral phase of the dispersed interferometer output and the repetition frequency of the laser. For an interferometer length of 50 m this approach has been compared to an independent phase counting laser interferometer. The obtained mutual agreement is better than 1.5 μm (3×10(-8)), with a statistical averaging of less than 200 nm. Our experiments demonstrate that dispersive interferometry with a frequency comb laser is a powerful method for accurate and non-incremental measurement of long distances. PMID:21451683

  5. 1-kHz-repetition-rate femtosecond Raman laser

    NASA Astrophysics Data System (ADS)

    Didenko, N. V.; Konyashchenko, A. V.; Kostryukov, P. V.; Losev, L. L.; Pazyuk, V. S.; Tenyakov, S. Yu

    2016-07-01

    A femtosecond Raman laser utilising compressed hydrogen is experimentally investigated under pumping by radiation from a 1-kHz-repetition-rate Ti : sapphire laser. In the regime of double-pulse pumping, the conditions are determined, which correspond to the minimal energy dispersion of Stokes pulses. The optical scheme is realised, which is capable of ensuring the long-term stability of the average power of the first Stokes component with a variation of less than 2%. The Stokes pulses are produced with a pulse duration of 60 fs and energy of 0.26 mJ at a conversion efficiency of 14%.

  6. Relationship Between Selected Strength and Power Assessments to Peak and Average Velocity of the Drive Block in Offensive Line Play.

    PubMed

    Jacobson, Bert H; Conchola, Eric C; Smith, Doug B; Akehi, Kazuma; Glass, Rob G

    2016-08-01

    Jacobson, BH, Conchola, EC, Smith, DB, Akehi, K, and Glass, RG. Relationship between selected strength and power assessments to peak and average velocity of the drive block in offensive line play. J Strength Cond Res 30(8): 2202-2205, 2016-Typical strength training for football includes the squat and power clean (PC) and routinely measured variables include 1 repetition maximum (1RM) squat and 1RM PC along with the vertical jump (VJ) for power. However, little research exists regarding the association between the strength exercises and velocity of an actual on-the-field performance. The purpose of this study was to investigate the relationship of peak velocity (PV) and average velocity (AV) of the offensive line drive block to 1RM squat, 1RM PC, the VJ, body mass (BM), and body composition. One repetition maximum assessments for the squat and PC were recorded along with VJ height, BM, and percent body fat. These data were correlated with PV and AV while performing the drive block. Peal velocity and AV were assessed using a Tendo Power and Speed Analyzer as the linemen fired, from a 3-point stance into a stationary blocking dummy. Pearson product analysis yielded significant (p ≤ 0.05) correlations between PV and AV and the VJ, the squat, and the PC. A significant inverse association was found for both PV and AV and body fat. These data help to confirm that the typical exercises recommended for American football linemen is positively associated with both PV and AV needed for the drive block effectiveness. It is recommended that these exercises remain the focus of a weight room protocol and that ancillary exercises be built around these exercises. Additionally, efforts to reduce body fat are recommended. PMID:24910958

  7. 215 μJ, 16 W femtosecond fiber laser for precision industrial micro-machining

    NASA Astrophysics Data System (ADS)

    Kim, Kyungbum; Peng, Xiang; Lee, Wangkuen; Gu, Xinhua; Mielke, Michael

    2014-03-01

    We describe unprecedented performance level from a femtosecond fiber laser system optimized for precision industrial micro-machining. The monolithic fiber chirped pulse amplifier chain enables system output of 215 μJ pulse energy, ~510 fs pulse duration and 16 W average power. We reveal the critical enabling technology to reach this unprecedented pulse energy level, the salient operating principles for the full chirped pulse amplification system, and the key experimental performance data for the laser system.

  8. Continuously tunable Yb:KYW femtosecond oscillator based on a tunable highly dispersive semiconductor mirror.

    PubMed

    Wnuk, P; Wasylczyk, P; Zinkiewicz, Ł; Dems, M; Hejduk, K; Regiński, K; Wójcik-Jedlińska, A; Jasik, A

    2014-07-28

    The optimized nonuniform growth process was used to achieve spatially dependent reflectivity and dispersions characteristics in a highly dispersive semiconductor mirror. The mirror, together with a semiconductor saturable absorber mirror (SESAM), was used to demonstrate a tunable femtosecond Yb:KYW oscillator. In the passive modelocking regime the laser could be continuously tuned over 3.5 nm spectral band around 1032 nm with high resolution, maintaining the average output power above 140 mW. PMID:25089448

  9. Sub-300-femtosecond operation from a MIXSEL.

    PubMed

    Mangold, Mario; Golling, Matthias; Gini, Emilio; Tilma, Bauke W; Keller, Ursula

    2015-08-24

    Peak power scaling of semiconductor disk lasers is important for many applications, but their complex pulse formation mechanism requires a rigorous pulse characterization to confirm stable fundamental modelocking. Here we fully confirm sub-300-fs operation of Modelocked Integrated eXternal-cavity Surface Emitting Lasers (MIXSELs) with record high peak power at gigahertz pulse repetition rates. A strain-compensated InGaAs quantum well gain section enables an emission wavelength in the range of Yb-doped amplifiers at ≈1030 nm. We demonstrate the shortest pulses from a MIXSEL with a duration of 253 fs with 240 W of peak power, the highest peak power generated from any MIXSEL to date. This peak power performance is comparable to conventional SESAM-modelocked VECSELs for the first time. At a 10-GHz pulse repetition rate we still obtained 279-fs pulses with 310 mW of average output power, which is currently the highest output power of any femtosecond MIXSEL. Continuous tuning of the pulse repetition rate has been demonstrated with sub-400-fs pulse durations and >225 mW of average output power between 2.9 and 3.4 GHz. The strain-compensated MIXSEL chip allowed for more detailed parameter studies with regards to different heat sink temperatures, pump power, and epitaxial homogeneity of the MIXSEL chip for the first time. We discuss in detail, how the critical temperature balance between quantum well gain and quantum well absorber, the partially saturated absorber and a limited epitaxial growth quality influence the overall device efficiency. PMID:26368179

  10. High average power, high repetition rate table-top soft x-ray lasers for applications in nanoscience and nanotechnology

    NASA Astrophysics Data System (ADS)

    Reagan, Brendan; Wernsing, Keith; Baumgarten, Cory; Durivage, Leon; Berrill, Mark; Curtis, Alden; Furch, Federico; Luther, Brad; Woolston, Mark; Patel, Dinesh; Menoni, Carmen; Shlyaptsev, Vyacheslav; Rocca, Jorge

    2014-03-01

    There is great interest in table-top sources of bright coherent soft x-ray radiation for nanoscale applications. We report the demonstration of a compact, high repetition rate soft x-ray laser operating at wavelengths between 10.9nm to 18.9nm, including the generation of 0.15mW average power at λ = 18.9nm and 0.1mW average power at λ = 13.9nm. These short wavelength lasers were driven by an all diode pumped, chirped pulse amplification laser based on cryogenically-cooled Yb:YAG amplifiers that produces 1 Joule, picosecond duration pulses at 100 Hz repetition rate. Irradiation of solid targets results in the production of plasmas with large transient population inversions on the 4d1S0 --> 4p1P1 transition of Ni-like ions. Optimization of this high repetition rate laser combined with the development of high shot capacity, rotating targets has allowed the uninterrupted operation of this soft x-ray laser for hundreds of thousands of consecutive shots, making it suitable for a number of applications requiring high photon flux at short wavelengths. Work was supported by the NSF ERC for Extreme Ultraviolet Science and Technology using equipment developed under NSF Award MRI-ARRA 09-561, and by the AMOS program of the Office of Basic Energy Sciences, US Department of Energy.