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Sample records for emerging terawatt picosecond

  1. Emerging terawatt picosecond CO{sub 2} laser technology

    SciTech Connect

    Pogorelsky, I.V.

    1997-09-01

    The first terawatt picosecond (TWps) CO{sub 2} laser is under construction at the BNL Accelerator Test Facility (ATF). TWps-CO{sub 2} lasers, having an order of magnitude longer wavelength than the well-known table-top terawatt solid state lasers, offer new opportunities for strong-field physics research. For laser wakefield accelerators (LWFA) the advantage of the new class of lasers is due to a gain of two orders of magnitude in the ponderomotive potential. The large average power of CO{sub 2} lasers is important for the generation of hard radiation through Compton back-scattering of the laser off energetic electron beams. The authors discuss applications of TWps-CO{sub 2} lasers for LWFA modules of a tentative electron-positron collider, for {gamma}-{gamma} (or {gamma}-lepton) colliders, for a possible table-top source of high-intensity x-rays and gamma rays, and the generation of polarized positron beams.

  2. Emerging terawatt picosecond CO{sub 2} laser technology and possible applications in accelerator physics

    SciTech Connect

    Pogorelsky, I.V.; Ben-Zvi, I.

    1997-07-01

    The first terawatt picosecond (TWps) CO{sub 2} laser is under construction at the BNL Accelerator Test Facility (ATF). TWps-CO{sub 2} lasers, having the order of magnitude longer wavelength than the well-known table-top terawatt solid state lasers, offer new opportunities for the strong-field physics research. For processes based on electro quiver motion, such as laser wakefield acceleration (LWFA), the advantage of the new class of lasers is due to a gain of two orders of magnitude in the ponderomotive potential for the same peak power. The large average power capability of CO{sub 2} lasers is important for the generation of hard radiation through Compton back-scattering of the laser off energetic electron beams, as well as for other applications. Among them are: LWFA modules of a tentative electron-positron collider, {gamma}-{gamma} (or {gamma}-lepton) collider, a possible table-top source of high-intensity x-rays and gamma rays and the generation of polarized positron beams.

  3. Terawatt Picosecond CO(sub 2) Laser Technology for High Energy Physics Applications

    SciTech Connect

    Pogorelsky, I. V.

    1998-07-05

    Demonstration of ultra-high acceleration gradients in the SM LWFA experiments put a next objective for the laser accelerator development to achieve a low-emittance monochromatic acceleration over extended interaction distances. The emerging picosecond terawatt (ps-TW) CO{sub 2} laser technology helps to meet this strategic goal. Among the considered examples are: the staged electron laser accelerator (STELLA) experiment, which is being conducted at the Brookhaven ATF, and the plasma-channeled LWFA. The long-wavelength and high average power capabilities of CO{sub 2} lasers maybe utilized also for generation of intense x-ray and gamma radiation through Compton back-scattering of the laser beams off relativistic electrons. We discuss applications of ps-TW CO{sub 2} lasers for a tentative {gamma}-{gamma} (or {gamma}-lepton) collider and generation of polarized positron beams.

  4. The first terawatt picosecond CO{sub 2} laser for advanced accelerator studies at the Brookhaven ATF

    SciTech Connect

    Pogorelsky, I.V.; Ben-Zvi, I.; Skaritka, J.

    1996-10-01

    The first terawatt picosecond C0{sub 2} laser system is under development at the Brookhaven Accelerator Test Facility. Presently operational 1 Joule 100-ps ATF laser will be upgraded with a 10 atm amplifier capable of delivery {approximately} 15 Joules of laser energy in a 3 ps pulse. We describe the design of the x-ray preionized 10 atm amplifier of a 10 liter active volume energized by a 1 MV, 200 kA transverse electric discharge. The amplifier, equipped with internal optics, permits the accommodation of a regenerative stage and a multi-pass booster in a relatively compact single discharge volume. The ATF terawatt C0{sub 2} laser shall become operational in 1997 to serve for laser acceleration, x-ray generation and other strong-field physics experiments.

  5. High-brightness picosecond ion beam source based on BNL Terawatt CO2 laser: Proof-of-principle experiments

    SciTech Connect

    Shkolnikov, Peter

    2012-10-04

    Under the continuing DOE support, we have: o assembled the basic experiment setup and then continued expanding it to include diverse diagnostics and to accommodate gas jet targets in addition to metal foils; o conducted an extensive study of our novel laser, significantly enhanced laser beam diagnostics, and improved relevant laser parameters; o turned our experiments into a truly international endeavor with active collaboration of close to 20 researchers in US, UK, and Germany; o conducted the first ever experiments with proton and ion acceleration by lasers interacting with overcritical plasma of gas jets; o for the first time directly observed radiation pressure acceleration of protons, including quasi-monoenergetic spectra promising for future applications; o for the first time directly observed quasi-stable, bubble-like plasma structures that likely evolved from relativistic laser-plasma solitons (post-solitons). Thus, we have confirmed a strong potential of a picosecond TW CO2 laser as a research tool in laser-plasma science and as a promising vehicle for future applications of laser ion acceleration. This has led to apparent increase of the interest in mid-IR laser ion acceleration. In particular, another major research group began extensive proton acceleration experiments with their own CO2 laser at UCLA. As a result, the mechanisms responsible for laser proton acceleration in gas jets have become somewhat clearer. It is also important to note that modest DOE funding played the role of a seed support ensuring the formation of a multinational research team, whose members contributed its time and equipment with value well in excess of that seed amount.

  6. Picosecond optoelectronic devices

    SciTech Connect

    Lee, C.L.

    1984-01-01

    Ever since the invention of picosecond lasers, scientists and electronic engineers have been dreaming of inventing electronic devices that can record in real time the physical and electronic events that take place on picosecond time scales. With the exception of the expensive streak camera, this dream has been largely unfullfilled. Today, a real-time oscilloscope with picosecond time resolution is still not available. To fill the need for even better time resolution, researchers have turned to optical pulses and thus a hybrid technology has emerged-picosecond optoelectronics. This technology, based on bulk photoconductors, has had a slow start. However, because of the simplicity, scaleability, and jitterfree nature of the devices, the technology has recently experienced a rapid growth. This volume reviews the major developments in the field of picosecond optoelectronics over the past decade.

  7. Status of the Leopard Laser Project in Nevada Terawatt Facility

    NASA Astrophysics Data System (ADS)

    Wiewior, Piotr P.; Astanovitskiy, A.; Aubry, G.; Batie, S.; Caron, J.; Chalyy, O.; Cowan, T.; Haefner, C.; Le Galloudec, B.; Le Galloudec, N.; Macaulay, D.; Nalajala, V.; Pettee, G.; Samek, S.; Stepanenko, Y.; Vesco, J.

    2009-06-01

    Nevada Terawatt Facility (NTF) currently operates a high-intensity laser system—Leopard. NTF already operates a powerful z-pinch device, called Zebra, for plasma and High Energy Density physics research. The unique research opportunities arise from the combination of NTF's terawatt Zebra z-pinch with 50-terawatt-class Leopard laser. This combination also provides opportunities to address fundamental physics of inertial fusion and high energy density physics with intense laser beam. We report on the status, design and architecture of the Leopard laser project. A first experiments carried out with Leopard will be also briefly mentioned.

  8. Manufacturing for Terawatt-Scale Energy Applications

    NASA Astrophysics Data System (ADS)

    Atwater, Harry

    2013-03-01

    Future energy conversion devices will make extensive use of nanostructured materials that must be manufactured at a scale compatible with terawatt-scale deployment. Specifically, future ultrahigh efficiency photovoltaic devices and modules will likely have little in common with today's photovoltaic technology but instead will be essentially complex optical integrated circuits with microscale and nanoscale critical dimensions for efficient optical spectrum splitting, light absorption and carrier transport. The challenge for nanomanufacturing is to realize the fabrication of these sophisticated device architectures with nanoscale features in high-volume low-cost commodity fabrication processes. I will describe examples of practical and scalable approaches to large-scale nanophotonic fabrication using recent advances in the research and commercial development. One example is epitaxial liftoff of thin-film single-crystal Si and III-V compound semiconductor absorbers, and layer-transfer printing techniques for single crystal film assembly of lifted film structures. Another is substrate conformable soft-imprint lithography provides a scalable method for the synthesis of low-cost large-area arrays of nano-patterned light-trapping structures or structures with engineered optical density of states. It is now well established that soft-imprint lithography has a deep-subwavelength resolution, maintained over a large area. Directions for future research and applications to other energy technologies will be surveyed. Supported by the US Department of Energy.

  9. Experimental plasma astrophysics using a T{sup 3} (Table-top Terawatt) laser

    SciTech Connect

    Tajima, T.

    1996-11-01

    Lasers that can deliver immense power of Terawatt (10{sup 12}W) and can still compactly sit on a Table-Top (T{sup 3} lasers) emerged in the 1990s. The advent of these lasers allows us to access to regimes of astronomical physical conditions that once thought impossible to realize in a terrestrial laboratory. We touch on examples that include superhigh pressure materials that may resemble the interior of giant planets and white dwarfs and of relativistic temperature plasmas that may exist in the early cosmological epoch and in the neighborhood of the blackhole event horizon.

  10. Experimental Plasma Astrophysics Using a T3 (Table-Top Terawatt) Laser

    NASA Astrophysics Data System (ADS)

    Tajima, T.

    1996-11-01

    Lasers that can deliver immense power of Terawatt (1012 W) and can still compactly sit on a Table-Top (T3 lasers) emerged in the 1990s. The advent of these lasers allows us to access to regimes of astronomical physical conditions that once thought impossible to realize in a terrestrial laboratory. We touch on examples that include superhigh pressure materials that may resemble the interior of giant planets and white dwarfs and of relativistic temperature plasmas that may exist in the early cosmological epoch and in the neighborhood of the blackhole event horizon.

  11. Picosecond Chemical and Biological Events.

    ERIC Educational Resources Information Center

    Rentzepis, P. M.

    1978-01-01

    Describes a currently used picosecond spectroscopy system capable of reliably recording picosecond events. Two areas of picosecond research are discussed: one concerns the interaction of electrons in fluids; the second, the primary events in vision. (Author/HM)

  12. Development of a 100-terawatt hybrid femtosecond laser system

    NASA Astrophysics Data System (ADS)

    Losev, V.; Alekseev, S.; Ivanov, N.; Kovalchuk, B.; Mikheev, L.; Mesyats, G.; Panchenko, Yu.; Puchikin, A.; Ratakhin, N.; Yastremsky, A.

    2010-09-01

    Terawatt hybrid (solid state/gas) laser (THL-100) system on the basis of Ti:sapphire starting complex (50 fs, 5 mJ) and photochemical XeF(C-A) amplifier with the aperture of 24 cm is presented. Laser system is built at Institute of High Current Electronics SD RAS, Tomsk, Russia. The design and peculiarities of optical pumping of XeF(C-A) amplifier, methods of pump power measuring, gain distribution across the active volume are discussed. The results of numerical modeling of the output parameters simulation are presented and one compared with first experimental results.

  13. Picosecond Imaging Circuit Analysis

    NASA Astrophysics Data System (ADS)

    Kash, Jeffrey A.

    1998-03-01

    With ever-increasing complexity, probing the internal operation of a silicon IC becomes more challenging. Present methods of internal probing are becoming obsolete. We have discovered that a very weak picosecond pulse of light is emitted by each FET in a CMOS circuit whenever the circuit changes logic state. This pulsed emission can be simultaneously imaged and time resolved, using a technique we have named Picosecond Imaging Circuit Analysis (PICA). With a suitable imaging detector, PICA allows time resolved measurement on thousands of devices simultaneously. Computer videos made from measurements on real IC's will be shown. These videos, along with a more quantitative evaluation of the light emission, permit the complete operation of an IC to be measured in a non-invasive way with picosecond time resolution.

  14. Broadly tunable picosecond ir source

    DOEpatents

    Campillo, A.J.; Hyer, R.C.; Shapiro, S.L.

    1980-04-23

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 ..mu..m picosecond pulses (1) pass through a 4.5 cm long LiNbO/sub 3/ optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO/sub 3/ optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 ..mu..m along both pump lines are 6 to 8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 ..mu..m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 ..mu..J of tunable radiation over the 14.8 to 18.5 ..mu..m region. The bandwidth and wavelength of both the 2 and 16 ..mu..m radiation output are controlled solely by the diffraction grating.

  15. Broadly tunable picosecond IR source

    DOEpatents

    Campillo, Anthony J.; Hyer, Ronald C.; Shapiro, Stanley J.

    1982-01-01

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 .mu.m picosecond pulses (1) pass through a 4.5 cm long LiNbO.sub.3 optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO.sub.3 optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 .mu.m along both pump lines are 6-8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 .mu.m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 .mu.J of tunable radiation over the 14.8 to 18.5 .mu.m region. The bandwidth and wavelength of both the 2 and 16 .mu.m radiation output are controlled solely by the diffraction grating.

  16. Picosecond beam monitor

    DOEpatents

    Schutt, D.W.; Beck, G.O.

    1974-01-01

    The current in the beam of a particle accelerator is monitored with picosecond resolution by causing the beam to impinge upon the center conductor of a coaxial line, generating a pulse of electromagnetic energy in response thereto. This pulse is detected by means such as a sampling oscilloscope. (Official Gazette)

  17. Ultrafast terawatt laser sources for high-field particle acceleration and short wavelength generation

    SciTech Connect

    Downer, M.C.; Siders, C.W.

    1996-12-31

    The Laser Sources working group concerned itself with recent advances in and future requirements for the development of laser sources relevant to high-energy physics (HEP) colliders, small scale accelerators, and the generation of short wave-length radiation. We heavily emphasized pulsed terawatt peak power laser sources for several reasons. First, their development over the past five years has been rapid and multi-faceted, and has made relativistic light intensity available to the advanced accelerator community, as well as the wider physics community, for the first time. Secondly, they have strongly impacted plasma-based accelerator research over the past two years, producing the first experimental demonstrations of the laser wakefield accelerator (LWFA) in both its resonantly-driven and self-modulated forms. Thirdly, their average power and wall-plug efficiency currently fall well short of projected requirements for future accelerators and other high average power applications, but show considerable promise for improving substantially over the next few years. A review of this rapidly emerging laser technology in the context of advanced accelerator research is therefore timely.

  18. Picosecond Spin Caloritronics

    NASA Astrophysics Data System (ADS)

    Cahill, David G.

    The coupling of spin and heat, i.e., spin caloritronics, gives rise to new physical phenomena in nanoscale spin devices and new ways to manipulate local magnetization. Our work in this field takes advantage of recent advances in the measurement and understanding of heat transport at the nanoscale using ultrafast lasers. We use a picosecond duration pump laser pulses as a source of heat and picosecond duration probe laser pulses to detect changes in temperature, spin accumulation, and spin transfer torque using a combination of time-domain thermoreflectance and time-resolved magneto-optic Kerr effect Our pump-probe optical methods enable us to change the temperature of ferromagnetic layers on a picosecond time-scale and generate enormous heat fluxes on the order of 100 GW m-2 that persist for ~ 30 ps. Thermally-driven ultrafast demagnetization of a perpendicular ferromagnet leads to spin accumulation in a normal metal and spin transfer torque in an in-plane ferromagnet. The data are well described by models of spin generation and transport based on differences and gradients of thermodynamic parameters. The spin-dependent Seebeck effect of a perpendicular ferromagnetic layer converts a heat current into spin current, which in turn can be used to exert a spin transfer torque (STT) on a second ferromagnetic layer with in-plane magnetization. Using a [Co,Ni] multilayer as the source of spin, an energy fluence of ~ 4 J m-2 creates thermal STT sufficient to induce ~ 1 % tilting of the magnetization of a 2 nm-thick CoFeB layer.

  19. Report of the terawatt laser pressure vessel committee

    SciTech Connect

    Woodle, M.H.; Beauman, R.; Czajkowski, C.; Dickinson, T.; Lynch, D.; Pogorelsky, I.; Skjaritka, J.

    2000-09-25

    In 1995 the ATF project sent out an RFP for a CO2 Laser System having a TeraWatt output. Eight foreign and US firms responded. The Proposal Evaluation Panel on the second round selected Optoel, a Russian firm based in St. Petersburg, on the basis of the technical criteria and cost. Prior to the award, BNL representatives including the principal scientist, cognizant engineer and a QA representative visited the Optoel facilities to assess the company's capability to do the job. The contract required Optoel to provide a x-ray preionized high pressure amplifier that included: a high pressure cell, x-ray tube, internal optics and a HV pulse forming network for the main discharge and preionizer. The high-pressure cell consists of a stainless steel pressure vessel with various ports and windows that is filled with a gas mixture operating at 10 atmospheres. In accordance with BNL Standard ESH 1.4.1 ''Pressurized Systems For Experimental Use'', the pressure vessel design criteria is required to comply with the ASME Boiler and Pressure Vessel Code In 1996 a Preliminary Design Review was held at BNL. The vendor was requested to furnish drawings so that we could confirm that the design met the above criteria. The vendor furnished drawings did not have all dimensions necessary to completely analyze the cell. Never the less, we performed an analysis on as much of the vessel as we could with the available information. The calculations concluded that there were twelve areas of concern that had to be addressed to assure that the pressure vessel complied with the requirements of the ASME code. This information was forwarded to the vendor with the understanding that they would resolve these concerns as they continued with the vessel design and fabrication. The assembled amplifier pressure vessel was later hydro tested to 220 psi (15 Atm) as well as pneumatically to 181 psi (12.5 Atm) at the fabricator's Russian facility and was witnessed by a BNL engineer. The unit was shipped to the

  20. The TARANIS laser : A multi-terawatt system for laser plasma physics

    NASA Astrophysics Data System (ADS)

    Lewis, C. L. S.; Nersisyan, G.; Borghesi, M.; Doria, D.; Dromey, B.; Dzelzainis, T.; Makita, M.; McKeever, K.; Riley, D.; White, S.; Marlow, D.; Williams, G.; Zepf, M.

    2012-11-01

    The Terawatt Apparatus for Relativistic And Non-linear Interdisciplinary Science (TARANIS), installed in the Centre for Plasma Physics at the Queen's University Belfast, supports a wide ranging science program, including laser-driven particle acceleration, X-ray lasers and high energy density physics experiments. We present (1) an overview of the laser facility, (2) results of preliminary investigations on proton acceleration, laser action at 13.9 nm and Kα sources and (3) speculation on future experiments using these extreme sources.

  1. 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.

  2. Picosecond buildup and relaxation of intense stimulated emission in GaAs

    SciTech Connect

    Ageeva, N. N.; Bronevoi, I. L. Zabegaev, D. N.; Krivonosov, A. N.

    2013-04-15

    In support of the idea developed previously based on circumstantial evidence, we have found that stimulated emission emerges in GaAs and its intensity increases with a picosecond delay relative to the front of powerful picosecond optical pumping that produced a dense electron-hole plasma. The emission intensity relaxes with decreasing pumping with a characteristic time of {approx}10 ps. We have derived the dependences of the delay time, the relaxation time, and the duration of the picosecond emission pulse on its photon energy. The estimates based on the fact that the relaxation of emission is determined by electron-hole plasma cooling correspond to the measured relaxation time.

  3. 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.

  4. Simultaneous High-Resolution 2-Dimensional Spatial and 1-Dimensional Picosecond Streaked X-ray Pinhole Imaging

    SciTech Connect

    Steel, A B; Nagel, S R; Dunn, J; Baldis, H A

    2012-05-03

    A Kentech x-ray streak camera was run at the LLNL Compact Multipulse Terawatt (COMET) laser to record simultaneous space- and time-resolved measurements of picosecond laser-produced plasmas. Four different x-ray energy channels were monitored using broad-band filters to record the time history of Cu targets heated at irradiances of 10{sup 16} - 10{sup 19} W/cm{sup 2}. Through the Cu filter channel, a time-resolution below 3ps was obtained. Additionally, an array of 10 {micro}m diameter pinholes was placed in front of the camera to produce multiple time-resolved x-ray images on the photocathode and time-integrated images on the phosphor with 10 and 15 times magnification, respectively, with spatial resolution of <13 {micro}m.

  5. Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Jukna, Vytautas; Jarnac, Amélie; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

    2016-06-01

    Acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

  6. Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses.

    PubMed

    Jukna, Vytautas; Jarnac, Amélie; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

    2016-06-01

    Acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum. PMID:27415357

  7. A 10-Hz Terawatt Class Ti:Sapphire Laser System: Development and Applications

    SciTech Connect

    Sharma, A.K.; Smedley, J.; Tsang, T.; Rao, T.

    2010-01-12

    We developed a two stage Ti:Sapphire laser system to generate 16 mJ/80fs laser pulses at the pulse repetition rate of 10 Hz. The key deriver for the present design is implementing a highly efficient symmetric confocal pre-amplifier and employing a simple, inexpensive synchronization scheme relying only on a commercial digital delay-generator. We characterized the amplified pulses in spatial-, spectral-, and temporal-domains. The laser system was used to investigate various nonlinear optical processes, and to modify the optical properties of metal- and semiconductor-surfaces. We are currently building a third amplifier to boost the laser power to the multi-terawatt range.

  8. Picosecond DPSS laser technology for OPCPA pumping

    NASA Astrophysics Data System (ADS)

    Vaupel, Andreas; Bodnar, Nathan; Webb, Benjamin; Shah, Lawrence; Richardson, Martin

    2014-02-01

    We present the design and challenges of a diode-pumped solid-state (DPSS) system to amplify picosecond pulses to high pulse energies and high average powers. We discuss our implemented solutions to mitigate thermal effects and present the obtained performance of the picosecond pulse amplification at the multi-10-MW level. Our here presented picosecond DPSS laser is well suited for pumping an optical parametric chirped-pulse amplification (OPCPA) system. Several laser technologies have been employed to pump OPCPA systems and we show how our DPSS system compares in performance to the other approaches.

  9. Transport in ultra-dense plasmas produced by a picosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Mehlman, G.; Burkhalter, P. G.; Newman, D. A.

    1992-03-01

    This report presents recent experimental results obtained with the Table Top Terawatt laser at the Ultrafast Science Laboratory (University of Michigan). Interaction of the picosecond laser pulse with an overdense plasma was investigated with spectroscopic observations in the XUV range using a compact 1 m grazing incidence spectrograph. The emission from laser-irradiated targets made of silicon wafers coated with aluminum layers of variable thicknesses (from 100 to 5000 A) was recorded to allow spectral line intensity measurements from silicon and aluminum L-shell ions. The experiment was conducted using laser irradiation at both wavelengths lambda L = 1.06 or 0.53 microns. The laser energy penetration depths were derived from the variation of the XUV spectral intensities with the different layer thicknesses. The values obtained cover the range 300-700 A at lambda L = 1.06 microns and 250-400 A at lambda L = 0.53 microns. The smaller penetration depth determined at the laser doubled frequency corroborates earlier x-ray results in the keV range at the same laboratory. The penetration depths derived provide a better understanding of the electron heat transport phenomena, supporting in particular the assumption of thermal condition in an overdense plasma.

  10. Picosecond x-ray science.

    SciTech Connect

    Landahl, E.; Reis, D.; Wang, J.; Young, L.

    2006-01-01

    The report discusses the exciting times for short pulse X-rays and the current users of the technology in the United States. Tracking nuclear motions with X-rays transcends scientific disciplines and includes Biology, Materials Science, Condensed Matter and Chemistry. 1 picosecond accesses many phenomena previously hidden at 100ps. Synchrotron advantage over laser plasma and LCLS is that it's easily tunable. There is a large and diverse user community of this technology that is growing rapidly. A working group is being formed to implement 'fast track' Phases 1 and 2 which includes tunable, polarized, monochromatic, focused X-rays; variable pulse length (1 to 100ps) and 1 kHz, 10{sup 9} X-rays/s with 1% bandwidth. ERL would be a major advance for ultrafast time-resolved studies.

  11. Fundamentals of picosecond laser ultrasonics.

    PubMed

    Matsuda, Osamu; Larciprete, Maria Cristina; Li Voti, Roberto; Wright, Oliver B

    2015-02-01

    The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned. PMID:24998119

  12. Carrier-envelope phase stabilization of a terawatt level chirped pulse amplifier for generation of intense isolated attosecond pulses.

    PubMed

    Gademann, Georg; Plé, Fabien; Paul, Pierre-Mary; Vrakking, Marc J J

    2011-12-01

    We demonstrate the first carrier-envelope phase (CEP)-stabilized chirped pulse amplification system with pulse peak-powers in the terawatt regime. The system, which eventually is intended to be used in the generation of isolated attosecond pulses, consists of two consecutive multipass amplification stages. The first amplification stage is a commercial CEP-stable kHz system including a single 13-pass amplifier reaching a pulse energy of 2.3 mJ. Pulses are picked after the first stage at a repetition rate of 50 Hz and are further amplified in a 5-pass power-amplifier to pulse energies that reach up to 80 mJ before compression. After compression the pulse energy is 35mJ at a pulse duration of 32 fs, signifying a peak power of 1.1 terawatt. Peak-powers exceeding 1.5 TW should easily be achievable by improving the efficiency of the grating compressor. The CEP-stability of the terawatt system is demonstrated by single shot measurements of the residual CEP jitter at the full repetition rate and show an excellent root-mean-square value of 315 mrad. PMID:22273885

  13. Design and experimental results on a terawatt magnetically controlled plasma opening switch

    SciTech Connect

    Savage, M.E.; Simpson, W.W.; Mendel, C.W. Jr.; McDaniel, D.H.; Levine, J.S.; Tucker, T.S.

    1998-05-01

    The magnetically controlled plasma opening switch (MCPOS) is an advanced plasma opening switch that utilizes magnetic fields to improve operation. Magnetic fields always dominate terawatt, pulsed power plasma opening switches. For that reason, the MCPOS uses controlled applied magnetic fields with magnitude comparable to the self-magnetic field of the storage inductor. One applied field holds the plasma in place while energy accumulates in the storage inductor, then another applied field pushes the plasma away from the cathode to allow energy to flow downstream. Over a ten month period, an MCPOS was designed, built, and tested on DECADE Module 2 at Physics International. The peak drive current was 1.8 MA in 250 ns. The output parameters were up to 1 MA into an electron beam load. The radiation temporal pulse width averaged 60 nanoseconds full-width at half-maximum. The peak load voltage ranged from one to two megavolts. The experiments demonstrated efficient power flow through a long, low-impedance magnetically insulated transmission line between the magnetically controlled plasma opening switch and the load.

  14. Diagnosing Pulsed Power Produced Plasmas with X-ray Thomson Scattering at the Nevada Terawatt Facility

    NASA Astrophysics Data System (ADS)

    Valenzuela, J. C.; Krauland, C.; Mariscal, D.; Krasheninnikov, I.; Beg, F. N.; Wiewior, P.; Covington, A.; Presura, R.; Ma, T.; Niemann, C.; Mabey, P.; Gregori, G.

    2015-11-01

    We present experimental results on X-ray Thomson scattering (XRTS) at the Nevada Terawatt Facility (NTF) to study current driven plasmas. Using the Leopard laser, ~ 30 J and pulse width of 0.8 ns, we generated He- α emission (4.75 keV) from a thin Ti foil. Initial parameter scans showed that the optimum intensity is ~ 1015W/cm2 with a foil thickness of 2 μm for forward X-ray production. Bandwidth measurements of the source, using a HAPG crystal in the Von Hamos configuration, were found to be ΔE/E ~ 0.01. Giving the scattering angle of our experimental setup of 129 degrees and X-ray probing energy, the non-collective regime was accessed. The ZEBRA load was a 3 mm wide, 500 μm thick, and 10 mm long graphite foil, placed at one of the six current return posts. Estimates of the plasma temperature, density and ionization state were made by fitting the scattering spectra with dynamic structure factor calculations based on the random phase approximation for the treatment of charged particle coupling. The work was partially funded by the Department of Energy grant number DE-NA0001995.

  15. Staged Z-pinch Simulations for the UNR, Nevada Terawatt Zebra Facility

    NASA Astrophysics Data System (ADS)

    Ney, Paul; Rahman, Hafiz; Wessel, Frank; Narkis, Jeff; Valenzuela, Julio; Beg, Farhat; Presura, Radu; Darling, Tim; McKee, Erik; Covington, Aaron

    2015-11-01

    We simulate a Staged Z-pinch imploded on the 1 MA, 130 ns, 100 kJ, Nevada Terawatt Zebra Facility. The load is a magnetized, cylindrical, double gas-puff, plasma liner imploding onto a plasma target. Simulations use the 2-1/2 D, radiation-MHD code, MACH2. Three different liner gases are evaluated: Ar, Kr, and Xe and the target is either: DD, or DT, with a liner-plasma radius of: 1.0 cm and 2.0 cm, and a 5.0-mm thickness. Initial conditions are optimized to produce the highest neutron yield. Shocks propagate at different speeds in the liner and target, leading to a shock front at the interface. Magnetosonic shock waves pre-heat the target plasma and provide a stable implosion. The shock front provides a secondary conduction channel which builds up during implosion. The axial magnetic field controls the MRT instability and traps α-particles, leading to ignition. Magnetic flux is compressed, and at peak parameters the magnetic field and current density exceed, by an order of magnitude, values outside the pinch, providing a magneto-inertial confinement. A smaller radius provides 102 -103 × higher neutron yield. Funded by the US Department of Energy, ARPA-E, Control Number 1184-1527.

  16. MeV electron acceleration by sub-terawatt laser pulses in near critical density plasmas

    NASA Astrophysics Data System (ADS)

    Goers, Andy; Hine, George; Feder, Linus; Miao, Bo; Salehi, Fatholah; Milchberg, Howard

    2015-11-01

    We demonstrate laser-plasma acceleration of high charge electron beams to the 10 MeV scale using ultrashort laser pulses with as little energy as 10 mJ. This result is made possible by an extremely dense and thin hydrogen gas jet where even sub-terawatt laser pulses are well above the critical power for relativistic self-focusing, and the 10 mJ pulses can drive a self-modulated wakefield accelerator. Total charge up to 0.5 nC is measured for energies >1 MeV. Acceleration is correlated to the presence of an intense, coherent, broadband light flash, associated with wavebreaking, which can radiate more than 3% of the laser energy in a sub-femtosecond bandwidth consistent with half-cycle optical emission. Our results enable truly portable applications of laser-driven acceleration, such as low dose radiography, ultrafast probing of matter, and isotope production. This work supported by DTRA and the US Department of Energy.

  17. Airbreathing Laser Propulsion Experiments with 1 {mu}m Terawatt Pharos IIILaser: Part 2

    SciTech Connect

    Myrabo, L. N.; Lyons, P. W.; Jones, R. A.; Liu, S.; Manka, C.

    2011-11-10

    This basic research study examines the physics of airbreathing laser propulsion at the extreme flux range of 1-2x10{sup 11} W/cm{sup 2}--within the air breakdown threshold for l {mu}m radiation--using the terawatt Pharos III neodymium-glass pulsed laser. Six different experimental setups were employed using a 34 mm line focus with 66 {mu}m focal waist, positioned near the flat impulse surface. The 2nd Campaign investigated impulse generation with the laser beam focused at grazing incidence across near horizontal target surfaces, with pulse energies ranging from 55 to 186 J, and pulse-widths of 2 to 30 ns FWHM. Laser generated impulse was measured with a horizontal Plexiglas registered ballistic pendulum equipped with either a steel target insert or 0.5 Tesla permanent magnet (NEIT-40), to quantify changes in the momentum coupling coefficient (C{sub M}). Part 2 of this 2-part paper covers Campaign no. 2 results including C{sub M} performance data, and long exposure color photos of LP plasma phenomena.

  18. Airbreathing Laser Propulsion Experiments with 1 {mu}m Terawatt Pharos III Laser: Part 1

    SciTech Connect

    Myrabo, L. N.; Lyons, P. W.; Jones, R. A.; Liu, S.; Manka, C.

    2011-11-10

    This basic research study examines the physics of airbreathing laser propulsion at the extreme flux range of 1-2x10{sup 11} W/cm{sup 2}--within the air breakdown threshold for l {mu}m radiation--using the terawatt PHAROS III neodymium-glass pulsed laser. Six different experimental setups were tested using a 34 mm line focus with 66 {mu}m focal waist, positioned near the flat impulse surface. The first campaign investigated impulse generation with the beam oriented almost normal to the target surface, with energies ranging from 23 to 376 J, and pulses of 5 to 30 ns FWHM. Air breakdown/ plasma dynamics were diagnosed with GOI cameras and color photography. Laser generated impulse was quantified with both vertical pendulums and piezoelectric pressure transducers using the standard performance metric, C{sub M}--the momentum coupling coefficient. Part 1 of this 2-part paper covers Campaign no. 1 results including laser plasma diagnostics, pressure gage and vertical pendulum data.

  19. Passively CEP-stabilized frontend for few cycle terawatt OPCPA system

    NASA Astrophysics Data System (ADS)

    Budriūnas, Rimantas; Stanislauskas, Tomas; Varanavičius, Arūnas

    2015-09-01

    We report the recent results on development of a CEP-stable 1 kHz repetition rate TW-class OPCPA system driven by femtosecond Yb:KGW and picosecond Nd:YAG pump sources. Seed pulses with spectra spanning over an octave are produced in a continuum generator pumped by CEP-stable pulses from a difference frequency generator operated at 1.3-1.6 μm. After amplification in NOPA, pulses with energy up to 70 μJ and spectra supporting durations of 5 fs are obtained. Sub-70 mrad CEP jitter at the output of system frontend is demonstrated.

  20. Lidar receivers for picosecond remote sensing

    NASA Technical Reports Server (NTRS)

    Stoyanov, D. V.; Dreischuh, T. N.

    1992-01-01

    The lidars of picosecond resolution are an attractive tool for remote probing of some highly dynamic objects like sea subsurface waters, small-scale turbulences in the atmosphere, etc. The picosecond lasers are suitable illuminating sources, but the main restrictions are due to the lack of proper receiving methods, combining the both high temporal and amplitude resolution, good sensitivity, short integration time, and wide dynamic range. The methods for short pulse measurements are not suitable for picosecond lidars, operating at low level, with highly dynamic signals. The streak-cameras are of high cost, lower sensitivity, and lower dynamic range (approximately 10(exp 3)). Because of the background, the single quantum regime in photomultipliers (PMT) is ineffective. The sampling of highly dynamic optical signals with resolution less than or equal to 1ns is a serious problem, limiting the application of the high speed PMT-MCP (microchannel plate) in the picosecond lidar systems. The goal of this work is to describe the use of a new photodetection technique which combines the picosecond resolution with the high amplitude resolution, dynamic range, and sensitivity.

  1. Analysis of Picosecond Pulsed Laser Melted Graphite

    DOE R&D Accomplishments Database

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  2. Design of a Command-Triggered Plasma Opening Switch for Terawatt Applications

    SciTech Connect

    SAVAGE,MARK E.; MENDEL,C.W.; SEIDEL,DAVID B.

    1999-10-29

    Inductive energy storage systems can have high energy density, lending to smaller, less expensive systems. The crucial element of an inductive energy storage system is the opening switch. This switch must conduct current while energy is stored in an inductor, then open quickly to transfer this energy to a load. Plasma can perform this function. The Plasma Opening Switch (POS) has been studied for more than two decades. Success with the conventional plasma opening switch has been limited. A system designed to significantly improve the performance of vacuum opening switches is described in this paper. The gap cleared of plasma is a rough figure-of-merit for vacuum opening switches. Typical opened gaps of 3 mm are reported for conventional switches. The goal for the system described in this paper is more than 3 cm. To achieve this, the command-triggered POS adds an active opening mechanism, which allows complete separation of conduction and opening. This separation is advantageous because of the widely different time scales of conduction and opening. The detrimental process of magnetic field penetration into the plasma during conduction is less important in this switch. The opening mechanism duration is much shorter than the conduction time, so penetration during opening is insignificant. Opening is accomplished with a fast magnetic field that pushes plasma out of the switch region. Plasma must be removed from the switch region to allow high voltage. This paper describes some processes important during conduction and opening, and show calculations on the trigger requirements. The design of the switch is shown. This system is designed to demonstrate both improved performance and nanosecond output jitter at levels greater than one terawatt. An amplification mechanism is described which reduces the trigger energy. Particle-in-cell simulations of the system are also shown.

  3. Picosecond lasers with the dynamical operation control

    NASA Astrophysics Data System (ADS)

    Mikheev, N. G.; Morozov, V. B.; Olenin, A. N.; Yakovlev, D. V.

    2016-04-01

    Numerical model for simulation of generation process in advanced pulse-periodic high-peak-power picosecond diode-pumped Nd:YAG and Nd:YLF lasers has been developed. The model adequately describes picosecond pulse formation governed by active and passive mode-locking, negative feedback and adjustable loss level in the oscillator cavity. Optical jitter of output pulses attributed to laser generation development from spontaneous noise level was evaluated using statistical analysis of calculation results. In the presented laser scheme, minimal jitter value on the level ~40 ps was estimated.

  4. Production of Multi-Terawatt Time-Structured CO{sub 2} Laser Pulses for Ion Acceleration

    SciTech Connect

    Haberberger, Dan; Tochitsky, Sergei; Gong Chao; Joshi, Chan

    2010-11-04

    The UCLA Neptune Laboratory CO{sub 2} laser system has been recently upgraded to produce 3ps multi-terawatt 10{mu}m laser pulses. The laser energy is distributed over several 3 ps pulses separated by 18 ps. These temporally structured pulses are applied for laser driven ion acceleration in an H{sub 2} gas jet at a measured plasma density of 2x10{sup 19} cm{sup -3}. Protons in excess of 20 MeV have been observed in the forward direction and with energy spreads ({Delta}E/E{approx}10%).

  5. Development of rike techniques using picosecond lasers

    SciTech Connect

    Schauer, M.W.; Pellin, M.J.; Biwer, B.M.; Gruen, D.M.

    1987-09-25

    The sensitivity of the Raman-induced Kerr effect is greatly enhanced through the use of picosecond lasers. Experiments in dilute solutions of benzene indicate that sensitivity at the monolayer level is achievable. Applications to transparent media, to fluorescing samples, and to in situ measurements of electrode surfaces are discussed.

  6. Ultrasensitive coherent Raman technique with picosecond lasers

    SciTech Connect

    Schauer, M.W.; Pellin, M.J.; Biwer, B.M.; Gruen, D.M.

    1986-01-01

    The sensitivity of the Raman-induced Kerr effect is greatly enhanced through the use of picosecond lasers. Experiments in dilute solutions of benzene indicate that sensitivity at the monolayer level is achievable. Applications to transparent media, to fluorescing samples, and to in situ measurements of electrode surfaces are discussed.

  7. Electron acceleration in preformed plasma channels with terawatt CO{sub 2} laser

    SciTech Connect

    Pogorelsky, I.V.

    1995-02-01

    Extended cylindrical plasma channels produced under gas breakdown by axicon-focused laser beams may be used as optical waveguides in laser-driven electron accelerators. Plasma channeling of the laser beams will help to maintain a high acceleration gradient over many Rayleigh lengths. In addition, the rarefied gas density channel produced after the optical gas breakdown, and followed by a plasma column expansion, reduces multiple scattering of the electron beam. A high-power picosecond C0{sub 2}laser operational at the ATF and being further upgraded to the 1 TW level is considered as the source for a plasma channel formation and as the laser accelerator driver. We show how various laser accelerator schemes including beat wave, wake field, and Inverse Cherenkov accelerator benefit from using a channeled short-pulse C0{sub 2}laser as a driver.

  8. Design of a Command-Triggered Plasma Opening Switch for Terawatt Applications

    SciTech Connect

    Mendel, Jr., C.W.; Savage, M.E.; Seidel, D.B.; Shoup, R.W.

    1999-06-23

    Inductive energy storage pulsed power systems can have high energy density, leading to smaller, less expensive systems. The crucial element of an inductive energy storage system is the opening switch. In microsecond and nanosecond pulsed power systems the plasma opening switch has been in use for more than twenty years. Though widely studied, application of the plasma opening switch (POS) has been limited in both performance ad understanding. The development of the triggered switch is aimed to address three important areas. First, complete de-coupling of the closed phase and the opening phase will allow improved performance, especialiy at longer conduction times. Second, the simplified physics allows for easier modeling because of a betterdefined geometry. Third, naturally, triggering will reduce jitter of the output pulse. Improving performance will allow longer conduction time, and triggering will negate the naturaIIy increased self- operating jitter at longer conduction time. The triggered switch system is based on moving the plasma switch armature with a magnetic field. Up unti} the time the armature is pushed away, it is held in place against the drive current magnetic pressure by a second magnetic field. We have demonstrated the components of this system [1], but never before has a plasma opening switch been opened by an independent signal. Our system is designed to deliver 1-2 terawatts of usable load power at multi-megavolt potentiak. We define usable load power as the product of load voltage and load cathode (boundary) current. The length of the vacuum storage inductor defines the 35 ns pulse length. This paper will show the design of the switch and rngger system, which is conservatively designed to provide a wide range of trigger signals. The trigger power for this system is important for cost reasons. The first experiments will use a trigger level of ten percent of the output pulse; we will describe design features intended to reduce the amount of

  9. A carrier-envelope-phase stabilized terawatt class laser at 1 kHz with a wavelength tunable option

    NASA Astrophysics Data System (ADS)

    Trallero, C. A.; Langdon, B.; Garlick, J.; Ren, X.; Wilson, D. J.; Summers, A. M.; Zigo, S.; Kling, M. F.; Lei, S.; Elles, C. G.; Poliakoff, E. D.; Carnes, K. D.; Kumarappan, V.; Ben-Itzhak, I.

    2015-05-01

    We demonstrate a chirped-pulse-amplified Ti:Sapphire laser system operating at 1 kHz, with 20 mJ pulse energy, 26 femtosecond pulse duration (0.77 terawatt), and excellent long term carrier-envelope-phase (CEP) stability. A new vibrational damping technique is implemented to significantly reduce vibrational noise on both the laser stretcher and compressor, thus enabling a single-shot CEP noise value of 250 mrad RMS over 1 hour and 300 mrad RMS over 9 hours. This is, to the best of our knowledge, the best long term CEP noise ever reported for any terawatt class laser. This laser is also used to pump a white-light-seeded optical parametric amplifier, producing 6 mJ of total energy in the signal and idler. Due to preservation of the CEP in the white-light generated signal and passive CEP stability in the idler, this laser system promises synthesized laser pulses spanning multi-octaves of bandwidth at an unprecedented energy scale. NSF-MRI grant No:1229672, DOD-DURIP grant No. FA2386-12-1-3014, DOE grant No. DE-FG02-86ER13491, NSF Fellowship DGE-1247193 (DJW), and NDSEG Fellowship (AMS).

  10. Carrier-envelope-phase stabilized terawatt class laser at 1 kHz with a wavelength tunable option.

    PubMed

    Langdon, Benjamin; Garlick, Jonathan; Ren, Xiaoming; Wilson, Derrek J; Summers, Adam M; Zigo, Stefan; Kling, Matthias F; Lei, Shuting; Elles, Christopher G; Wells, Eric; Poliakoff, Erwin D; Carnes, Kevin D; Kumarappan, Vinod; Ben-Itzhak, Itzik; Trallero-Herrero, Carlos A

    2015-02-23

    We demonstrate a chirped-pulse-amplified Ti:Sapphire laser system operating at 1 kHz, with 20 mJ pulse energy, 26 femtosecond pulse duration (0.77 terawatt), and excellent long term carrier-envelope-phase (CEP) stability. A new vibrational damping technique is implemented to significantly reduce vibrational noise on both the laser stretcher and compressor, thus enabling a single-shot CEP noise value of 250 mrad RMS over 1 hour and 300 mrad RMS over 9 hours. This is, to the best of our knowledge, the best long term CEP noise ever reported for any terawatt class laser. This laser is also used to pump a white-light-seeded optical parametric amplifier, producing 6 mJ of total energy in the signal and idler with 18 mJ of pumping energy. Due to preservation of the CEP in the white-light generated signal and passive CEP stability in the idler, this laser system promises synthesized laser pulses spanning multi-octaves of bandwidth at an unprecedented energy scale. PMID:25836493

  11. Picosecond photoconductivity of natural and CVD diamonds

    NASA Astrophysics Data System (ADS)

    Garnov, Serge V.; Pimenov, Sergej M.; Ralchenko, Victor G.; Klimentov, Sergei M.; Konov, Vitali I.; Korotoushenko, K. G.; Obraztsova, E. D.; Plotnikova, S. P.; Sagatelyan, D. M.; Holly, Sandor

    1995-07-01

    Photoexcitation and recombination of nonequilibrium charge carriers in both natural gemstone diamonds and CVD (chemical vapor deposition) polycrystalline diamond films in UV spectrum regions have been investigated. Transient picosecond photoconductivity technique applied permitted to conduct measurements with the time resolution better than 200 picoseconds and to register a charge carrier concentration value as low as 1020 - 1013 cm-3. The dependencies of photocurrent amplitude as a function of incident laser radiation intensity in the range from 103 to 1010 W/cm2 have been obtained. Charge carrier lifetimes had been measured and charge carrier drift mobility were estimated. It is shown that the electronic properties of high quality thick CVD diamond films are comparable to those of the most perfect natural type IIa crystals. Investigation of Raman and luminescence spectra of diamonds have been performed along with scanning electron microscopy studies to characterize bulk and surface structure of tested specimens.

  12. High Power Picosecond Laser Pulse Recirculation

    SciTech Connect

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  13. Double regenerative amplification of picosecond pulses

    NASA Astrophysics Data System (ADS)

    Bai, Zhen-ao; Chen, Li-yuan; Bai, Zhen-xu; Chen, Meng; Li, Gang

    2012-04-01

    An double Nd:YAG regenerative amplification picosecond pulse laser is demonstrated under the semiconductor saturable absorption mirror(SESAM) mode-locking technology and regenerative amplification technology, using BBO crystal as PC electro-optic crystal. The laser obtained is 20.71ps pulse width at 10 KHz repetition rate, and the energy power is up to 4W which is much larger than the system without pre-amplification. This result will lay a foundation for the following amplification.

  14. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.

    1993-03-01

    The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.

  15. A picosecond high pressure gas switch

    SciTech Connect

    Cravey, W.R.; Poulsen, P.P.; Pincosy, P.A.

    1992-06-01

    Work is being done to develop a high pressure gas switch (HPGS) with picosecond risetimes for UWB applications. Pulse risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at high pressures and higher electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With these high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized on the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with lab data.

  16. Picosecond electron-optic diagnostics in laser studies

    NASA Astrophysics Data System (ADS)

    Prokhorov, A. M.

    The papers included in this volume provide an overview of research aimed at the development of methods and instrumentation for ultrahigh-speed electron-optic detection and of their applications in laser physics, laser fusion, fiber-optic communication, picosecond spectroscopy, and photobiology. Topics discussed include the physics of a picosecond electron-optic converter, the aberration theory for cathode lenses, picosecond and subpicosecond laser sources, and a beam deflection system for a subpicosecond electron-optic converter.

  17. Development of 100 terawatt hybrid laser system on base of photochemically driven XeF(C-A) amplifier

    NASA Astrophysics Data System (ADS)

    Losev, V.; Alekseev, S.; Ivanov, N.; Kovalchuk, B.; Mikheev, L.; Mesyats, G.; Panchenko, Yu.; Ratakhin, N.; Yastremsky, A.

    2012-07-01

    Development of terawatt hybrid (solid state/gas) laser (THL-100) system on the basis of Ti:sapphire starting complex and photochemical XeF(C-A) amplifier with the aperture of 24 cm is presented. Laser system is built at Institute of High Current Electronics SD RAS, Tomsk, Russia. The results of numerical modeling of the output parameters are discussed and first experimental results are presented. Simulation is shown that active medium of XeF(C-A) amplifier has gain in range of (1.8-4.5)×10-3cm-1 and it allows to extract by femtosecond pulse up to 3 J. This promises 60 TW output power to be produced in 50 fs pulse. In the first experiments when 2 mJ and 1 ps pulse was injected in XeF(C-A) amplifier the ˜1 J output energy and ˜10 TW power of was obtained.

  18. Ultrasensitive coherent Raman technique with picosecond lasers

    SciTech Connect

    Schauer, M.W.; Pellin, M.J.; Biwer, B.M.; Gruen, D.M.

    1987-02-16

    The use of picosecond, Q-switched lasers and advanced polarization schemes has led to the development of a coherent Raman technique with the sensitivity of coherent anti-Stokes Raman spectroscopy experiments but without the troublesome phase-matching requirements. Experiments in dilute solutions of benzene indicate a limit of sensitivity for the current apparatus of 2.5 x 10/sup -4/ M in two minutes of signal averaging over 150 cm/sup -1/. Possible applications to the in situ study of passive films and thin films on transparent media are discussed.

  19. Stimulated light forces using picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Bloch, Immanuel; Goepfert, A.; Haubrich, D.; Lison, F.; Schuetze, R.; Wynands, Robert; Meschede, Dieter

    1997-05-01

    Using the stimulated force exerted by counterpropagating picosecond laser pulses from a mode-locked Ti:Sapphire laser we were able to focus a beam of laser-cooled cesium atoms along one dimension to about 57% of its original width in the detection zone. The force profile was measured outside and inside the overlap region of the pulses and found to be in agreement with an earlier theoretical prediction. A brief theoretical account of the interaction of atoms with pulsed laser light based on the optical Bloch equations is given.

  20. Picosecond High Pressure Gas Switch experiment

    SciTech Connect

    Cravey, W.R.; Freytag, E.K.; Goerz, D.A.; Poulsen, P.; Pincosy, P.A.

    1993-08-01

    A high Pressure Gas Switch has been developed and tested at LLNL. Risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere pressures. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at higher pressures and electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With such high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized using the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with experimental data. Modifications made to the WASP HV pulser in order to drive the HPGS will also be discussed. Recovery times of less than 1 ms were recorded without gas flow in the switch chambers. Low pressure synthetic air was used as the switch dielectric. Longer recovery times were required when it was necessary to over-voltage the switch.

  1. Picosecond laser ablation of porcine sclera

    NASA Astrophysics Data System (ADS)

    Góra, Wojciech S.; Harvey, Eleanor M.; Dhillon, Baljean; Parson, Simon H.; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    Lasers have been shown to be successful in certain medical procedures and they have been identified as potentially making a major contribution to the development of minimally invasive procedures. However, the uptake is not as widespread and there is scope for many other applications where laser devices may offer a significant advantage in comparison to the traditional surgical tools. The purpose of this research is to assess the potential of using a picosecond laser for minimally invasive laser sclerostomy. Experiments were carried out on porcine scleral samples due to the comparable properties to human tissue. Samples were prepared with a 5mm diameter trephine and were stored in lactated Ringer's solution. After laser machining, the samples were fixed in 3% glutaraldehyde, then dried and investigated under SEM. The laser used in the experiments is an industrial picosecond TRUMPF TruMicro laser operating at a wavelength of 1030nm, pulse length of 6ps, repetition rate of 1 kHz and a focused spot diameter of 30μm. The laser beam was scanned across the samples with the use of a galvanometer scan head and various ablation patterns were investigated. Processing parameters (pulse energy, spot and line separation) which allow for the most efficient laser ablation of scleral tissue without introducing any collateral damage were investigated. The potential to create various shapes, such as linear incisions, square cavities and circular cavities was demonstrated.

  2. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  3. Timing characteristics of Large Area Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Adams, B. W.; Elagin, A.; Frisch, H. J.; Obaid, R.; Oberla, E.; Vostrikov, A.; Wagner, R. G.; Wang, J.; Wetstein, M.

    2015-09-01

    The LAPPD Collaboration was formed to develop ultrafast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub-picosecond laser. We observe single-photoelectron time resolutions of a 20 cm × 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 μm, and median gains higher than 107. The RMS measured at one particular point on an LAPPD detector is 58 ps, with ± 1σ of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  4. Patterning of ITO with picosecond lasers

    NASA Astrophysics Data System (ADS)

    Račiukaitis, Gediminas; Brikas, Marijus; Gedvilas, Mindaugas; Darčianovas, Gediminas

    2007-02-01

    Indium-tin oxide (ITO) is the main material for making transparent electrodes in electronic devices and flat panel displays. Laser-direct-write technology has been widely used for patterning ITO. The well defined edges and good electrical isolation at a short separation are required for the modern OLED and RFID devices of high packing density. High repetition rate lasers with a short, picosecond pulse width offer new possibilities for high efficiency structuring of transparent conductors on glass and other substrates. The results of patterning the ITO film on glass with picosecond lasers at various wavelengths are presented. Laser radiation initiated ablation of the material, forming trenches in ITO. Profile of the trenches was analyzed with a phase contrast optical microscope, a stylus type profiler, SEM and AFM. Clean removal of the ITO layer was achieved with the 266 nm radiation when laser fluence was above the threshold at 0.20 J/cm2, while for the 355 nm radiation the threshold was higher, above 0.46 J/cm2. The glass substrate was damaged in the area where the fluence was higher than 1.55 J/cm2. The 532 nm radiation allowed getting well defined trenches, but a lot of residues in the form of dust were generated on the surface. UV radiation at the 266 nm provided the widest working window for ITO ablation without damage of the substrate. Use of UV laser radiation with fluences close to the ablation threshold made it possible to minimize surface contamination and the recast ridge formation during the process.

  5. Relativistically Self-Channeled Femtosecond Terawatt Lasers for High-Field Physics and X-Ray Generation

    SciTech Connect

    Borisov, A.B.; Boyer, K.; Cameron, S.M.; Luk, T.S.; McPherson, A.; Nelson, T.; Rhodes, C.K.

    1999-01-01

    Optical channeling or refractive guiding processes involving the nonlinear interaction of intense femtosecond optical pulses with matter in the self-focussing regime has created exciting opportunities for next-generation laser plasma-based x-ray sources and directed energy applications. This fundamentally new form of extended paraxial electromagnetic propagation in nonlinear dispersive media such as underdense plasma is attributed to the interplay between normal optical diffraction and intensity-dependent nonlinear focussing and refraction contributions in the dielectric response. Superposition of these mechanisms on the intrinsic index profile acts to confine the propagating energy in a dynamic self-guiding longitudinal waveguide structure which is stable for power transmission and robust compression. The laser-driven channels are hypothesized to support a degree of solitonic transport behavior, simultaneously stable in the space and time domains (group velocity dispersion balances self-phase modulation), and are believed to be self-compensating for diffraction and dispersion over many Rayleigh lengths in contrast with the defining characteristics of conventional diffractive imaging and beamforming. By combining concentrated power deposition with well-ordered spatial localization, this phenomena will also create new possibilities for production and regulation of physical interactions, including electron beams, enhanced material coupling, and self-modulated plasma wakefields, over extended gain distances with unprecedented energy densities. Harmonious combination of short-pulse x-ray production with plasma channeling resulting from a relativistic charge displacement nonlinearity mechanism in the terawatt regime (10{sup 18} W/cm{sup 2}) has been shown to generate high-field conditions conducive to efficient multi-kilovolt x-ray amplification and peak spectral brightness. Channeled optical propagation with intense short-pulse lasers is expected to impact several

  6. Picosecond photoresponse in van der Waals heterostructures.

    PubMed

    Massicotte, M; Schmidt, P; Vialla, F; Schädler, K G; Reserbat-Plantey, A; Watanabe, K; Taniguchi, T; Tielrooij, K J; Koppens, F H L

    2016-01-01

    Two-dimensional crystals such as graphene and transition-metal dichalcogenides demonstrate a range of unique and complementary optoelectronic properties. Assembling different two-dimensional materials in vertical heterostructures enables the combination of these properties in one device, thus creating multifunctional optoelectronic systems with superior performance. Here, we demonstrate that graphene/WSe2/graphene heterostructures ally the high photodetection efficiency of transition-metal dichalcogenides with a picosecond photoresponse comparable to that of graphene, thereby optimizing both speed and efficiency in a single photodetector. We follow the extraction of photoexcited carriers in these devices using time-resolved photocurrent measurements and demonstrate a photoresponse time as short as 5.5 ps, which we tune by applying a bias and by varying the transition-metal dichalcogenide layer thickness. Our study provides direct insight into the physical processes governing the detection speed and quantum efficiency of these van der Waals heterostuctures, such as out-of-plane carrier drift and recombination. The observation and understanding of ultrafast and efficient photodetection demonstrate the potential of hybrid transition-metal dichalcogenide-based heterostructures as a platform for future optoelectronic devices. PMID:26436565

  7. Dielectric breakdown induced by picosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

    1976-01-01

    The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger.

  8. Mitotic spindle studied using picosecond laser scissors

    NASA Astrophysics Data System (ADS)

    Baker, N. M.; Botvinick, E. L.; Shi, Linda; Berns, M. B.; Wu, George

    2006-08-01

    In previous studies we have shown that the second harmonic 532 nm, from a picosecond frequency doubled Nd:YAG laser, can cleanly and selectively disrupt spindle fiber microtubules in live cells (Botvinick et al 2004, Biophys. J. 87:4303-4212). In the present study we have ablated different locations and amounts of the metaphase mitotic spindle, and followed the cells in order to observe the fate of the irradiated spindle and the ability of the cell to continue through mitosis. Cells of the rat kangaroo line (PTK2) were stably transfected by ECFP-tubulin and, using fluorescent microscopy and the automated RoboLase microscope, (Botvinick and Berns, 2005, Micros. Res. Tech. 68:65-74) brightly fluorescent individual cells in metaphase were irradiated with 0.2447 nJ/micropulse corresponding to an irradiance of 1.4496*10^7 J/(ps*cm^2) . Upon irradiation the exposed part of the mitotic spindle immediately lost fluorescence and the following events were observed in the cells over time: (1) immediate contraction of the spindle pole towards the cut, (2) recovery of connection between pole and cut microtubule, (3) completion of mitosis. This system should be very useful in studying internal cellular dynamics of the mitotic spindle.

  9. Picosecond photoresponse in van der Waals heterostructures

    NASA Astrophysics Data System (ADS)

    Massicotte, M.; Schmidt, P.; Vialla, F.; Schädler, K. G.; Reserbat-Plantey, A.; Watanabe, K.; Taniguchi, T.; Tielrooij, K. J.; Koppens, F. H. L.

    2016-01-01

    Two-dimensional crystals such as graphene and transition-metal dichalcogenides demonstrate a range of unique and complementary optoelectronic properties. Assembling different two-dimensional materials in vertical heterostructures enables the combination of these properties in one device, thus creating multifunctional optoelectronic systems with superior performance. Here, we demonstrate that graphene/WSe2/graphene heterostructures ally the high photodetection efficiency of transition-metal dichalcogenides with a picosecond photoresponse comparable to that of graphene, thereby optimizing both speed and efficiency in a single photodetector. We follow the extraction of photoexcited carriers in these devices using time-resolved photocurrent measurements and demonstrate a photoresponse time as short as 5.5 ps, which we tune by applying a bias and by varying the transition-metal dichalcogenide layer thickness. Our study provides direct insight into the physical processes governing the detection speed and quantum efficiency of these van der Waals heterostuctures, such as out-of-plane carrier drift and recombination. The observation and understanding of ultrafast and efficient photodetection demonstrate the potential of hybrid transition-metal dichalcogenide-based heterostructures as a platform for future optoelectronic devices.

  10. Emerging ps-TW CO{sub 2} laser technology for high energy physics applications

    SciTech Connect

    Pogorelsky, I.V.

    1998-02-01

    A brief overview of laser acceleration techniques and a comparative analysis of the picosecond terawatt (ps-TW) CO{sub 2} laser technology versus T{sup 3} solid state lasers for prospective HEP applications. Special attention is given to two laser accelerator schemes. The first one is the far-field staged laser accelerator, STELLA, which is under exploration at the ATF using a CO{sub 2} laser. The second is a laser wakefield accelerator where ps-TW CO{sub 2} lasers have a great potential. Inverse to the laser accelerator, a prospective monochromatic x-ray source feasible at the ATF will also utilize a 50 MeV subpicosecond electron beam and the first ps-TW CO{sub 2} laser, PITER I.

  11. Optothermal response of plasmonic nanofocusing lens under picosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Du, Z.; Chen, C.; Traverso, L.; Xu, X.; Pan, L.; Chao, I.-H.; Lavine, A. S.

    2014-03-01

    This work studied the optothermal response of plasmonic nanofocusing structures under picosecond pulsed laser irradiation. The surface plasmon polariton is simulated to calculate the optical energy dissipation as the Joule heating source and the thermal transport process is studied using a two temperature model (TTM). At the picosecond time scale that we are interested in, the Fourier heat equation is used to study the electron thermal transport and the hyperbolic heat equation is used to study the lattice thermal transport. For comparison, the single temperature model (STM) is also studied. The difference between TTM and STM indicates that TTM provides more accurate estimates in the picosecond time scale and the STM results are only reliable when the local electron and lattice temperature difference is negligible.

  12. High power industrial picosecond laser from IR to UV

    NASA Astrophysics Data System (ADS)

    Saby, Julien; Sangla, Damien; Pierrot, Simonette; Deslandes, Pierre; Salin, François

    2013-02-01

    Many industrial applications such as glass cutting, ceramic micro-machining or photovoltaic processes require high average and high peak power Picosecond pulses. The main limitation for the expansion of the picosecond market is the cost of high power picosecond laser sources, which is due to the complexity of the architecture used for picosecond pulse amplification, and the difficulty to keep an excellent beam quality at high average power. Amplification with fibers is a good technology to achieve high power in picosecond regime but, because of its tight confinement over long distances, light undergoes dramatic non linearities while propagating in fibers. One way to avoid strong non linearities is to increase fiber's mode area. Nineteen missing holes fibers offering core diameter larger than 80μm have been used over the past few years [1-3] but it has been shown that mode instabilities occur at approximately 100W average output power in these fibers [4]. Recently a new fiber design has been introduced, in which HOMs are delocalized from the core to the clad, preventing from HOMs amplification [5]. In these so-called Large Pitch Fibers, threshold for mode instabilities is increased to 294W offering robust single-mode operation below this power level [6]. We have demonstrated a high power-high efficiency industrial picosecond source using single-mode Large Pitch rod-type fibers doped with Ytterbium. Large Pitch Rod type fibers can offer a unique combination of single-mode output with a very large mode area from 40 μm up to 100μm and very high gain. This enables to directly amplify a low power-low energy Mode Locked Fiber laser with a simple amplification architecture, achieving very high power together with singlemode output independent of power level or repetition rate.

  13. Molecular collision processes in the presence of picosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Lee, H. W.; George, T. F.

    1979-01-01

    Radiative transitions in molecular collision processes taking place in the presence of picosecond pulses are studied within a semiclassical formalism. An expression for adiabatic potential surfaces in the electronic-field representation is obtained, which directly leads to the evaluation of transition probabilities. Calculations with a Landau-Zener-type model indicate that picosecond pulses can be much more effective in inducing transitions than a single long pulse of the same intensity and the same total energy, if the intensity is sufficiently high that the perturbation treatment is not valid.

  14. An All-Optical Picosecond Switch in Polydiacetylene

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.

    2002-01-01

    Polydiacetylene derivative of 2-methyl-4-nitroaniline (PDAMNA) showed a picosecond switching property. This phenomenon was demonstrated by wave guiding a cw He-Ne laser collinearly with a mode-locked picosecond Nd:YAG laser at 532 nm through a hollow fiber coated on the inside with a thin film of PDAMNA. The z-scan investigations of PDAMNA thin film revealed that the PDAMNA system is a three level system and the switching is caused by excited state absorption of the He-Ne beam.

  15. Synchronization of sub-picosecond electron and laser pulses

    SciTech Connect

    Rosenzweig, J. B.; Le Sage, G. P.

    1999-07-12

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail.

  16. Synchronization of sub-picosecond electron and laser pulses

    SciTech Connect

    Rosenzweig, J.B.; Le Sage, G.P.

    1999-07-01

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail. (AIP) {copyright} {ital 1999 American Institute of Physics.}

  17. Molecular Simulation of Cell Membrane Deformation by Picosecond Intense Electric Pulse.

    PubMed

    Petrishia, Arockiasamy; Sasikala, Mohan

    2015-12-01

    The application of pulsed electric field is emerging as a new technique for cancer therapy. The irreversible electroporation is the major bioelectric effect to induce cell death. The pulsed electric field is transferred to target deep tissue non-invasively and precisely when the pulse duration is in picosecond regime. In this proposed work, the intense electric field with 100 ps pulse width is used for irreversible electroporation. If the electric field strength increases, the pore in the cell membrane enlarges, causing a loss of membrane intactness and the direct killing of cancer cells. This phenomenon is explored by molecular dynamics simulation. The electric field in the range of 0.8-5 V/nm is used for membrane dynamics. The membrane deformation occurs at the electric field of 5 V/nm. Picosecond pulsed electric field has a wealth of ultra-band spectrum, with extended time and enhanced spatial resolution and low signal distortion. The ultra-wide band antenna is used as a pulse delivery system for non-invasive skin cancer therapy. PMID:26054382

  18. Picosecond lasers for tattoo removal: a systematic review.

    PubMed

    Reiter, Ofer; Atzmony, Lihi; Akerman, Lehavit; Levi, Assi; Kershenovich, Ruben; Lapidoth, Moshe; Mimouni, Daniel

    2016-09-01

    Given that the pigment particles in tattoos have a relaxation time of <10 ns, picosecond lasers would be expected to be more effective than nanosecond lasers in tattoo removal. To systematically review the evidence regarding the effectiveness and safety of picosecond lasers for tattoo removal, Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and reference lists were searched for relevant trials. The primary outcome was >70 % clearance of tattoo pigment. Secondary outcomes were 90-100 % clearance of tattoo pigment, number of laser sessions required, and adverse effects. Eight trials were included, six with human participants (160 participants) and 2 with animal models. Seven of the eight trials explored the usage of either 755, 758, 795, 1064, or 1064/532-nm picosecond lasers for black and blue ink tattoos. In the human trials, 69-100 % of tattoos showed over 70 % clearance of pigment after 1-10 laser treatments. Reported side effects included pain, hyperpigmentation and hypopigmentation, blister formation and transient erythema, edema, and pinpoint bleeding. Included articles varied in type of laser investigated, mostly non-comparative studies and with a medium to high risk of bias. There is sparse evidence that picosecond lasers are more effective than their nanosecond counterparts for mainly black and blue ink tattoo removal, with minor side effects. PMID:27311768

  19. Picosecond lasers: the next generation of short-pulsed lasers.

    PubMed

    Freedman, Joshua R; Kaufman, Joely; Metelitsa, Andrea I; Green, Jeremy B

    2014-12-01

    Selective photothermolysis, first discussed in the context of targeted microsurgery in 1983, proposed that the optimal parameters for specific thermal damage rely critically on the duration over which energy is delivered to the tissue. At that time, nonspecific thermal damage had been an intrinsic limitation of all commercially available lasers, despite efforts to mitigate this by a variety of compensatory cooling mechanisms. Fifteen years later, experimental picosecond lasers were first reported in the dermatological literature to demonstrate greater efficacy over their nanosecond predecessors in the context of targeted destruction of tattoo ink. Within the last 4 years, more than a decade after those experiments, the first commercially available cutaneous picosecond laser unit became available (Cynosure, Westford, Massachusetts), and several pilot studies have demonstrated its utility in tattoo removal. An experimental picosecond infrared laser has also recently demonstrated a nonthermal tissue ablative capability in soft tissue, bone, and dentin. In this article, we review the published data pertaining to dermatology on picosecond lasers from their initial reports to the present as well as discuss forthcoming technology. PMID:25830248

  20. Picosecond Electric-Field-Induced Threshold Switching in Phase-Change Materials.

    PubMed

    Zalden, Peter; Shu, Michael J; Chen, Frank; Wu, Xiaoxi; Zhu, Yi; Wen, Haidan; Johnston, Scott; Shen, Zhi-Xun; Landreman, Patrick; Brongersma, Mark; Fong, Scott W; Wong, H-S Philip; Sher, Meng-Ju; Jost, Peter; Kaes, Matthias; Salinga, Martin; von Hoegen, Alexander; Wuttig, Matthias; Lindenberg, Aaron M

    2016-08-01

    Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag_{4}In_{3}Sb_{67}Te_{26}. Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales-faster than crystals can nucleate. This supports purely electronic models of threshold switching and reveals potential applications as an ultrafast electronic switch. PMID:27541475

  1. Picosecond Electric-Field-Induced Threshold Switching in Phase-Change Materials

    NASA Astrophysics Data System (ADS)

    Zalden, Peter; Shu, Michael J.; Chen, Frank; Wu, Xiaoxi; Zhu, Yi; Wen, Haidan; Johnston, Scott; Shen, Zhi-Xun; Landreman, Patrick; Brongersma, Mark; Fong, Scott W.; Wong, H.-S. Philip; Sher, Meng-Ju; Jost, Peter; Kaes, Matthias; Salinga, Martin; von Hoegen, Alexander; Wuttig, Matthias; Lindenberg, Aaron M.

    2016-08-01

    Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag4In3Sb67Te26 . Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales—faster than crystals can nucleate. This supports purely electronic models of threshold switching and reveals potential applications as an ultrafast electronic switch.

  2. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    NASA Astrophysics Data System (ADS)

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-02-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

  3. Recent progress in picosecond pulse generation from semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    This paper reviews the recent progress in producing picosecond optical pulses from semiconductor laser diodes. The discussion concentrates on the mode-locking of a semiconductor laser diode in an external resonator. Transform-limited optical pulses ranging from several picoseconds to subpicosecond durations have been observed with active and passive mode-locking. Even though continuing research on the influence of impurities and defects on the mode-locking process is still needed, this technique has good promise for being utilized in fiber-optic communication systems. Alternative methods of direct electrical and optical excitation to produce ultrashort laser pulses are also described. They can generate pulses of similar widths to those obtained by mode-locking. The pulses generated will find applications in laser ranging and detector response measurement.

  4. Picosecond pulse shaping by spectral phase and amplitude manipulation.

    PubMed

    Heritage, J P; Weiner, A M; Thurston, R N

    1985-12-01

    The temporal profile of ultrashort optical pulses may be tailored by physically manipulating the phase and the amplitude of frequency components that are spatially dispersed within a grating pulse compressor. Arbitrary pulse shapes may be synthesized subject only to the usual restrictions imposed by finite bandwidth and spatial resolution. We demonstrate this technique by generating a burst of evenly spaced picosecond pulses, a pulse doublet with odd field symmetry, and a burst of evenly spaced pulse doublets with odd field symmetry. PMID:19730501

  5. Picosecond time-domain electromagnetic scattering from conducting cylinders

    NASA Astrophysics Data System (ADS)

    Robertson, W. M.; Kopcsay, G. V.; Arjavalingam, G.

    1991-12-01

    The microwave scattering properties of conducting cylinders are characterized by measuring their response to picosecond-duration electromagnetic pulses. The ultrafast electromagnetic transients are generated and detected with optoelectronically pulsed antennas. The time-domain response gives physical insight into the scattering process. In addition, Fourier analysis is used to obtain the frequency dependence of the scattered amplitude and phase from 15 to 140 GHz.

  6. X-ray production with sub-picosecond laser pulses

    SciTech Connect

    Schappert, G.T.; Cobble, J.A.; Fulton, R.D.; Kyrala, G.A.

    1993-12-31

    The interaction of intense, sub-picosecond laser pulses with solid targets produces intense picosecond x-ray pulses. With focused laser pulses of several 10 {sup 18} W/cm{sup 2}, He-like and H-like line radiation from targets such as aluminum and silicon has been produced. The energy conversion efficiency from the laser pulse energy to the 1--2 keV line x-rays is nearly one percent. The duration of the line x-ray radiation is of the order of ten picoseconds, although this may be an upper estimate because of the temporal resolution of the x-ray streak camera. The spatial extent of the x-ray source region is only slightly larger than the laser focal spot, or about 10 {mu}m in diameter. With these characteristics, such x-ray sources emit an intensity of nearly 10{sup 14} W/cm{sup 2}. Experiments and modeling which led to the above conclusions will be discussed.

  7. Picosecond VUV anti-Stokes Raman laser pumped by a KrF laser

    NASA Astrophysics Data System (ADS)

    Takahashi, Akihiko; Maeda, Mitsuo; Muraoka, Katsunori; Akazaki, Masanori

    1989-02-01

    Generation of picosecond vacuum ultraviolet pulses by anti-Stokes stimulated Raman Scattering (ASRS) in hydrogen gas is reported. A tunable picosecond KrF excimer laser (30 ps FWHM, 12 mJ) is used as a pump source, and a series of anti-Stokes lines up to the 9th order (128.8 nm) is efficiently generated. The transient effects due to the finite decay time of the Raman medium are discussed for the present picosecond ASRS experiment.

  8. Stimulated Raman scattering of picosecond pulses in a YVO4 crystal

    NASA Astrophysics Data System (ADS)

    Zong, N.; Zhang, X. F.; Li, C. M.; Cui, D. F.; Xu, Z. Y.; Zhang, H. J.; Wang, J. Y.

    2008-12-01

    Stimulated Raman scattering (SRS) with a picosecond pulse in YVO4 crystals in a transient state was investigated. The picosecond gain of YVO4 crystals pumped by a 532-nm laser evaluated by means of the threshold was 16.13 cm/GW.

  9. Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1982-01-01

    Spectroscopic and excited state decay kinetics are reported for monomeric and polymeric forms of ultraviolet stabilizers in the 2-(2'-hydroxyphenyl)-benzotriazole and 2-hydroxybenzophenone classes. For some of these molecules in various solvents at room temperature, (1) ground state absorption spectra, (2) emission spectra, (3) picosecond time-resolved transient absorption spectra, (4) ground state absorption recovery kinetics, (5) emission kinetics, and (6) transient absorption kinetics are reported. In the solid state at low temperatures, emission spectra and their temperature dependent kinetics up to approximately 200K as well as, in one case, the 12K excitation spectra of the observed dual emission are also reported.

  10. Mechanical Properties of Nuclear Fuel Surrogates using Picosecond Laser Ultrasonics

    SciTech Connect

    David Hurley; Marat Khafizov; Farhad Farzbod; Eric Burgett

    2013-05-01

    Detailed understanding between microstructure evolution and mechanical properties is important for designing new high burnup nuclear fuels. In this presentation we discuss the use of picosecond ultrasonics to measure localize changes in mechanical properties of fuel surrogates. We develop measurement techniques that can be applied to investigate heterogeneous elastic properties caused by localize changes in chemistry, grain microstructure caused by recrystallization, and mechanical properties of small samples prepared using focused ion beam sample preparation. Emphasis is placed on understanding the relationship between microstructure and mechanical properties

  11. Signal averaging x-ray streak camera with picosecond jitter

    NASA Astrophysics Data System (ADS)

    Maksimchuk, A.; Kim, M.; Workman, J.; Korn, G.; Squier, J.; Du, D.; Umstadter, D.; Mourou, G.; Bouvier, M.

    1996-03-01

    We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband x-ray emission from an ultrashort pulse laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained.

  12. The Jefferson Lab Sub-picosecond X-ray Program

    NASA Astrophysics Data System (ADS)

    Boyce, J. R.; Benson, S. V.; Bohn, C. L.; Douglas, D. R.; Dylla, H. F.; Gubeli, J. F.; Happek, U.; Jordan, K.; Krafft, G. A.; Neil, G. R.; Piot, P.; Shinn, M. D.; Williams, G. P.

    2003-08-01

    The kW-class infrared (IR) Free Electron Laser (FEL) at Jefferson Lab had the capability of producing intracavity Thomson scattering of the IR off the electron beam thus producing high average flux, sub-picosecond x-rays. We have measured these x-rays and demonstrated the energy tuneability range from 3.5 keV to 18 keV. The corresponding flux and brightness has been estimated and will be discussed. This year, 2002, the FEL was disassembled and has been reconfigured to produce 10 kW average power IR. We present the estimated x-ray capabilities for the new FEL and discuss potential applications.

  13. Picosecond dynamics of photoexcited carriers in interacting silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Kořínek, Miroslav; Trojánek, František; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Kübel, Christian; Malý, Petr

    2016-07-01

    The non-radiative Auger carrier recombination plays an important role in physics and the application of semiconductor nanocrystals. Here we report on the effect of inter-nanocrystal carrier interaction on Auger recombination. We prepared a special set of samples containing silicon nanocrystals embedded in silicon oxide with well-defined geometry. The picosecond carrier recombination rate measured by femtosecond pump and probe technique was found to be strongly dependent on the inter-nanocrystal separation. The observed decrease of the decay rate with nanocrystal separation on the nanometer scale is interpreted in terms of the wave function overlap appearing in the relevant matrix element describing the recombination process.

  14. In Vitro picosecond ultrasonics in a single cell

    NASA Astrophysics Data System (ADS)

    Rossignol, C.; Chigarev, N.; Ducousso, M.; Audoin, B.; Forget, G.; Guillemot, F.; Durrieu, M. C.

    2008-09-01

    Ultrasonics signals at frequencies 5.7±0.1 and 6.8±0.1GHz are measured in two organelles of a single vegetal cell in vitro with a picosecond ultrasonic technique. Using standard values for cell optical index, ultrasound velocities of 1.6±0.1 and 2.0±0.1μm/ns are measured from several signals recorded in the vacuole and in the nucleus of a single Allium cepa cell, respectively. A 1μm lateral and 0.25μm depth resolution is attained.

  15. Picosecond conformational transition and equilibration of a cyclic peptide

    NASA Astrophysics Data System (ADS)

    Bredenbeck, Jens; Helbing, Jan; Sieg, Arne; Schrader, Tobias; Zinth, Wolfgang; Renner, Christian; Behrendt, Raymond; Moroder, Luis; Wachtveitl, Josef; Hamm, Peter

    2003-05-01

    Ultrafast IR spectroscopy is used to monitor the nonequilibrium backbone dynamics of a cyclic peptide in the amide I vibrational range with picosecond time resolution. A conformational change is induced by means of a photoswitch integrated into the peptide backbone. Although the main conformational change of the backbone is completed after only 20 ps, the subsequent equilibration in the new region of conformational space continues for times >16 ns. Relaxation and equilibration processes of the peptide backbone occur on a discrete hierarchy of time scales. Albeit possessing only a few conformational degrees of freedom compared with a protein, the peptide behaves highly nontrivially and provides insights into the complexity of fast protein folding.

  16. High-power picosecond fiber source for coherent Raman microscopy

    PubMed Central

    Kieu, Khanh; Saar, Brian G.; Holtom, Gary R.; Xie, X. Sunney; Wise, Frank W.

    2011-01-01

    We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal tissue obtained with the new source. PMID:19571996

  17. Picosecond imaging of low-density plasmas by electron deflectometry.

    PubMed

    Centurion, M; Reckenthaeler, P; Krausz, F; Fill, E E

    2009-02-15

    We have imaged optical-field ionized plasmas with electron densities as low as 10(13) cm(-3) on a picosecond timescale using ultrashort electron pulses. Electric fields generated by the separation of charges are imprinted on a 20 keV probe electron pulse and reveal a cloud of electrons expanding away from a positively charged plasma core. Our method allows for a direct measurement of the electron energy required to escape the plasma and the total charge. Simulations reproduce the main features of the experiment and allow determination of the energy of the electrons. PMID:19373367

  18. Amplification of picosecond pulses in F{sub 2}{sup -}:LiF crystals synchronously pumped by picosecond and nanosecond laser pulses

    SciTech Connect

    Basiev, Tasoltan T; Karasik, Aleksandr Ya; Konyushkin, V A; Osiko, Vyacheslav V; Papashvili, A G; Chunaev, D S

    2005-04-30

    A method for amplification of picosecond pulses in F{sub 2}{sup -}:LiF crystals synchronously pumped by picosecond and nanosecond pulses is proposed and demonstrated. Due to two-stage amplification of a train of 22-ps, 1150-nm SRS pulses generated by a PbMoO{sub 4} crystal, a power gain of (2-4)x 10{sup 3} is achieved and single 6-ps, 0.88-mJ pulses are obtained. (lasers)

  19. Femtosecond wavelength-tunable OPCPA system based on picosecond fiber laser seed and picosecond DPSS laser pump.

    PubMed

    Danilevičius, R; Zaukevičius, A; Budriūnas, R; Michailovas, A; Rusteika, N

    2016-07-25

    We present a compact and stable femtosecond wavelength-tunable optical parametric chirped pulse amplification (OPCPA) system. A novel OPCPA front-end was constructed using a multi-channel picosecond all-in-fiber source for seeding DPSS pump laser and white light supercontinuum generation. Broadband chirped pulses were parametrically amplified up to 1 mJ energy and compressed to less than 40 fs duration. Pulse wavelength tunability in the range from 680 nm to 930 nm was experimentally demonstrated. PMID:27464199

  20. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle.

    PubMed

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  1. Probing carrier dynamics in nanostructures by picosecond cathodoluminescence.

    PubMed

    Merano, M; Sonderegger, S; Crottini, A; Collin, S; Renucci, P; Pelucchi, E; Malko, A; Baier, M H; Kapon, E; Deveaud, B; Ganière, J-D

    2005-11-24

    Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials. In such experiments, a laser pulse normally excites several nanostructures at once. However, spectroscopic information may also be acquired using pulses from an electron beam in a modern electron microscope, exploiting a phenomenon called cathodoluminescence. This approach offers several advantages. The multimode imaging capabilities of the electron microscope enable the correlation of optical properties (via cathodoluminescence) with surface morphology (secondary electron mode) at the nanometre scale. The broad energy range of the electrons can excite wide-bandgap materials, such as diamond- or gallium-nitride-based structures that are not easily excited by conventional optical means. But perhaps most intriguingly, the small beam can probe a single selected nanostructure. Here we apply an original time-resolved cathodoluminescence set-up to describe carrier dynamics within single gallium-arsenide-based pyramidal nanostructures with a time resolution of 10 picoseconds and a spatial resolution of 50 nanometres. The behaviour of such charge carriers could be useful for evaluating elementary components in quantum computers, optical quantum gates or single photon sources for quantum cryptography. PMID:16306988

  2. Picosecond and femtosecond laser ablation of hard tissues

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexander A.; Makropoulou, Mersini I.; Kar, Ajoy K.; Khabbaz, Marouan

    1996-12-01

    In this study, the interaction of picosecond and femtosecond pulsed laser radiation with human dental tissue was investigated experimentally, as this unexplored field is expected to be a potential alternative in powerful laser processing of biomedical structures. Dentin ablation rate experiments were performed by using teeth sections of different thickness. Dental tissue samples were irradiated in air with i) a regenerative amplifier laser at 1064 nm, pulse duration 110 ps, ii) the second harmonic laser at 532 nm, pulse duration 100 ps, and iii) a picosecond tunable dye amplifier at 595 nm, pulse width 800 fs. In all the experiments the pulse repetition rate was 10 Hz. The ablation rate per pulse at different energy fluence settings was calculated by measuring the time needed for the perforation of the whole dental sample thickness. Short laser pulses can confine thermal energy within the optical zone, which maximizes photothermal and photomechanical mechanisms of interaction. Tissue ablation rates were found to be comparable to or better than other nanosecond lasers, and left smooth surfaces, free of thermal damage.

  3. High-pulse-energy mode-locked picosecond oscillator

    NASA Astrophysics Data System (ADS)

    Chao, Yang; Chen, Meng; Li, Gang

    2014-02-01

    We report on a high-pulse-energy solid-state picosecond Nd:YVO4 oscillator with cavity-dumping. The laser is end-pumped by an 808 nm laser diode and passively mode-locked with a semiconductor saturable absorption mirror (SESAM). In pure cw-mode-locking, this laser produced 2.5 W of average power at a pulse repetition rate of 40 MHz and pulse duration around 12 ps. A cavity dumping technique using an intra-cavity BBO electro-optic crystal to which bidirectional voltage was applied was adopted, effectively improving the cavity-dumping rate. Tunable high repetition rate from 100 kHz to 1 MHz was achieved. With electro-optic cavity dumper working at 1 MHz repetition rate, we achieved average power 594 mW. The laser includes a 5 mm long, a-cut, 0.5% doped Nd:YVO4 crystal with a 5-degree angle at one end face. Laser radiation is coupled out from the crystal end face with a 5-degree angle, without requiring insertion of a thin-film polarizer (TFP), thus simplifying the laser structure. This picosecond laser system has the advantages of compact structure and high stability, providing a good oscillator for regenerative amplifiers.

  4. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    PubMed Central

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  5. Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

    2016-03-01

    In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, <=50um with ps laser, and <=20um with sub-ps laser, respectively was observed as a criteria of selecting the laser pulse width. The effects of laser processing parameters on speed and efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

  6. Investigating the influence of a weak continuous-wave-trigger on picosecond supercontinuum generation.

    PubMed

    Li, Qian; Li, Feng; Wong, Kenneth K Y; Lau, Alan Pak Tao; Tsia, Kevin K; Wai, P K A

    2011-07-18

    We numerically study the impacts of introducing a minute continuous-wave (CW) trigger on the properties of picosecond supercontinuum (SC) generation. We show that this simple triggering approach enables active control of not only the bandwidth, but more importantly the temporal coherence of SC. Detailed numerical simulations suggest that depending on the wavelength of the CW-trigger the multiple higher-order four-wave mixing (FWM) components generated by the CW-trigger can create either a relatively more stochastic or a more deterministic beating effect on the pump pulse, which has significant implications on how soliton fission and the onset of SC are initiated in the presence of noise. By controlling the CW-trigger wavelengths, the rogue solitons emerged in SC generation can exhibit high-degree of temporal coherence and pulse-to-pulse intensity stability. The present study provides a valuable insight on how the initial soliton fission can be initiated in a more controllable manner such that SC generation with both high temporal coherence and stability can be realized. PMID:21934736

  7. Three-dimensional imaging of biological cells with picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Danworaphong, Sorasak; Tomoda, Motonobu; Matsumoto, Yuki; Matsuda, Osamu; Ohashi, Toshiro; Watanabe, Hiromu; Nagayama, Masafumi; Gohara, Kazutoshi; Otsuka, Paul H.; Wright, Oliver B.

    2015-04-01

    We use picosecond ultrasonics to image animal cells in vitro—a bovine aortic endothelial cell and a mouse adipose cell—fixed to Ti-coated sapphire. Tightly focused ultrashort laser pulses generate and detect GHz acoustic pulses, allowing three-dimensional imaging (x, y, and t) of the ultrasonic propagation in the cells with ˜1 μm lateral and ˜150 nm depth resolutions. Time-frequency representations of the continuous-wavelet-transform amplitude of the optical reflectivity variations inside and outside the cells show GHz Brillouin oscillations, allowing the average sound velocities of the cells and their ultrasonic attenuation to be obtained as well as the average bulk moduli.

  8. Picosecond Acoustic Measurement of Anisotropic Properties of Thin Films

    SciTech Connect

    Perton, M.; Rossignol, C.; Chigarev, N.; Audoin, B.

    2007-03-21

    Properties of thin metallic films have been studied extensively by means of laser-picosecond ultrasonics. Generation of longitudinal and shear waves via thermoelastic mechanism and large source has been only demonstrated for waves vectors along the normal to the interface. However, such measurements cannot provide complete information about elastic properties of films. As it has been already shown for nanosecond ultrasonics, the knowledge of group or phase velocities in several directions for sources with small lateral size allows determining the stiffness tensor coefficients of a sample. The experimental set-up was prepared to obtain the thinnest size for the source to achieve acoustic diffraction. The identification of the stiffness tensor components, based on the inversion of the bulk waves phase velocities, is applied to signals simulated and experimentally recorded for a material with hexagonal properties. First estimation of stiffness tensor coefficients for thin metallic film 2.1 {mu}m has been performed.

  9. Monolithic millimeter-wave and picosecond electronic technologies

    SciTech Connect

    Talley, W.K.; Luhmann, N.C.

    1996-03-12

    Theoretical and experimental studies into monolithic millimeter-wave and picosecond electronic technologies have been undertaken as a collaborative project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Coherent Millimeter-Wave Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. The work involves the design and fabrication of monolithic frequency multiplier, beam control, and imaging arrays for millimeter-wave imaging and radar, as well as the development of high speed nonlinear transmission lines for ultra-wideband radar imaging, time domain materials characterization and magnetic fusion plasma applications. In addition, the Coherent Millimeter-Wave Group is involved in the fabrication of a state-of-the-art X-band ({approximately}8-11 GHz) RF photoinjector source aimed at producing psec high brightness electron bunches for advanced accelerator and coherent radiation generation studies.

  10. Advantages of Picosecond Laser Machining for Cutting-Edge Technologies

    NASA Astrophysics Data System (ADS)

    Moorhouse, C.

    The demand to reduce the size, weight and material cost of modern electronic devices results in a requirement for precision micromachining to aid product development. Examples include making smaller and more powerful smartphones with brighter displays, eliminating the requirement for post-process cleaning and machining the latest bio- absorbable medical stents. The pace of innovation in high-tech industries has led to ultrafast (picosecond) industrial lasers becoming an important tool for many applications and the high repetition rates now available help to meet industrial throughput levels. This is due to the unique operating regime (megawatts of peak power) enabling clean cutting and patterning of sensitive materials and thin films used in a number of novel devices and allows micromachining of wide bandgap, "difficult" materials such as glass.

  11. Mechanical characterization of temperature-sensitive objects using picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Dehoux, T.; Audoin, B.; Zouani, O.; Durrieu, M. C.

    2011-01-01

    Biological objects are exquisitely sensitive to temperature variations and their mechanical characterization is often a challenge when using the picosecond ultrasonics technique. To reduce the laser-induced temperature rise, we place single biological cells on a thin metal transducer and we focus the laser beam that generates the acoustic waves at frequencies <= 150 GHz on the rear side of the transducer. The acoustic waves propagate through the transducer and are partially transmitted to the cell to create the so-called Brillouin oscillations. The frequency of these oscillations provides a direct measurement of the sound velocity. The simultaneous measurement of the acoustic reflection coefficient at the transducer/cell interface allows the determination of both the density and the compressibility of the cell.

  12. Picosecond spectroscopy of hydrogenated MBE-GaAs

    NASA Astrophysics Data System (ADS)

    Capizzi, M.; Coluzza, C.; Frankl, P.; Frova, A.; Colocci, M.; Gurioli, M.; Vinattieri, A.; Sacks, R. N.

    1991-04-01

    Picosecond-resolved and steady-state photoluminescence at LHe temperature in low-energy ion-gun hydrogenated GaAs/GaAlAs heterostructures are reported. The exciton in the GaAs layer shows an increase in lifetime - up to a factor of 3 - for moderate hydrogenation, followed by a sharp decrease below the value for the untreated sample, for higher H doses. Luminescence efficiency shows a consistent behavior. Incorporation of H generates a strong D-A band falling ˜64 meV below the gap energy. The behavior for heavy hydrogenation indicates the formation of a new type of deep defect, not ascribed to surface damage, because of the protective GaAlAs layer, plus the fact that the excitonic emission of the latter shows no variation.

  13. Effect of laser pulse duration in picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Dehoux, T.; Perton, M.; Chigarev, N.; Rossignol, C.; Rampnoux, J.-M.; Audoin, B.

    2006-09-01

    An optical grating has been introduced in a picosecond ultrasonics experiment, in order to vary continuously the duration of the laser beam pulse from 0.1to150ps. The evolution of the measured signal has been observed and analyzed through the comparison with a theoretical approach based on a two-temperature model. The latter allows matching the acoustic echoes together with the thermal background and the coincidence peak, for each pulse duration and at any time scale. The broadening of the acoustic echoes and the disappearing of its Brillouin component, along with the diminishing of the thermal coincidence peak, have been demonstrated when increasing the pulse duration. For a constant incident pulse energy, the efficiency of acoustic generation is optimum for the shortest pulses. Nevertheless, for longer pulses designed to obtain thermal conditions below the ablation threshold, acoustic generation could be enhanced.

  14. Picosecond laser-induced water condensation in a cloud chamber.

    PubMed

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-01

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient. PMID:27607654

  15. Picosecond laser welding of similar and dissimilar materials.

    PubMed

    Carter, Richard M; Chen, Jianyong; Shephard, Jonathan D; Thomson, Robert R; Hand, Duncan P

    2014-07-01

    We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld. PMID:25089985

  16. Retinal threshold studies for nanosecond and picosecond visible laser pulses

    NASA Astrophysics Data System (ADS)

    Roach, William P.; DiCarlo, Cheryl D.; Noojin, Gary D.; Stolarski, David J.; Amnotte, Rodney E.; Smith, Audrey B.; Rogers, Mark E.; Cain, Clarence P.

    1995-05-01

    Threshold measurements for Minimum Visible Lesions (MVL) at the retina are reported for 60 picoseconds (ps) and 4 nanoseconds (ns), single laser pulses in rhesus monkey eyes using a visible wavelength of 532 nanometers (nm) from a doubled Nd:YAG laser. The 50% probability for damage (ED50) dosages are calculated for 1 hour and 24 hour post exposures using 95% fiducial limits. For both pulsewidths, the threshold values calculated by probit analysis decrease between the 1 hour and 24 hour ophthalmoscopic evaluations. The ED50 value determined for the 60 ps pulsewidth was less than half the value at 4 ns (0.43 (mu) J/60 ps vs. 0.90 (mu) J/4 ns at 24 hours) for both readings. Of the 136 exposures for pulse energies ranging from 0.03 to 5.0 (mu) J no hemorrhagic lesions were produced for either pulsewidth studied. However, at 6.6 (mu) J one intraretinal hemorrhagic lesion was observed for 60 ps. The slope of the probit curve was higher for 60 ps when compared with the 4 ns value (3.03 at 60 ps vs. 2.68 at 4 ns). MVL threshold doses calculated are comparable with those reported in the literature. However, the 4 ns MVL values is less than one order of magnitude (a factor 4.7) above the Maximum Permissible Exposure (MPE) level as defined by the 'American National Standard For The Safe Use Of Lasers', ANSI Z136.1-19932. We present the current MVL data as it compares with previous data obtained for picosecond and femtosecond laser pulse thresholds and provide a preliminary assessment of how the ANSI MPE standard might be amended.

  17. Synchronization of Sub-Picosecond Electron and Laser Pulses

    SciTech Connect

    Rosenzweig, J.B.; Le Sage G.P.

    2000-08-15

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is subpicosecond, with tens of femtosecond synchronization implied for next-generation experiments. Typically, an RF electron accelerator is synchronized to a short pulse laser system by detecting the repetition signal of a laser oscillator, adjusted to an exact subharmonic of the linac RF frequency, and multiplying or phase locking this signal to produce the master RF clock. Pulse-to-pulse jitter characteristic of self-mode-locked laser oscillators represents a direct contribution to the ultimate timing jitter between a high intensity laser focus and electron beam at the interaction point, or a photocathode drive laser in an RF photoinjector. This timing jitter problem has been addressed most seriously in the context of the RF photoinjector, where the electron beam properties are sensitive functions of relative timing jitter. The timing jitter achieved in synchronized photocathode drive laser systems is near, or slightly below one picosecond. The ultimate time of arrival jitter of the beam at the photoinjector exit is typically a bit smaller than the photocathode drive-laser jitter due to velocity compression effects in the first RF cell of the gun. This tendency of the timing of the electron beam arrival at a given spatial point to lock to the RF lock is strongly reinforced by use of magnetic compression.

  18. Ultrafast Optical Beam Deflection in a Planar Waveguide for High Dynamic Range Recording at Picosecond Resolution

    SciTech Connect

    Sarantos, C H; Heebner, J E

    2008-07-02

    We report the latest performance of an ultrafast, all-optical beam deflector based on a prism array imprinted in a planar waveguide. The deflector enables single-shot, high dynamic range optical recording with picosecond resolution.

  19. All solid-state picosecond flashlamp pumped oscillator-amplifier Nd:YAG laser system

    NASA Astrophysics Data System (ADS)

    Jelinkova, Helena; Cech, Miroslav; Kubecek, Vaclav; Dombrovsky, Andrej; Diels, Jean-Claude M.; Stintz, Andreas

    2005-03-01

    Flashlamp pumped oscillator - three amplifiers Nd:YAG picosecond laser system mode-locked with multiple quantum well (MQW) saturable absorber was developed and investigated. 80 ps long pulses with the energy of 120 mJ were generated.

  20. Picosecond x-ray measurements from 100 eV to 30 keV

    SciTech Connect

    Attwood, D.T.; Kauffman, R.L.; Stradling, G.L.

    1980-10-15

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices.

  1. Timing high-speed microprocessor circuits using picosecond imaging circuit analysis

    NASA Astrophysics Data System (ADS)

    Steen, Steven E.; McManus, Moyra K.; Manzer, Dennis G.

    2001-04-01

    IBM Research has developed a time resolved imaging technique, Picosecond Imaging Circuit Analysis (PICA), which uses single photon events to analyze signals in modern microprocessors on a picosecond time scale. This paper will describe the experimental setup as well as the data management software. A case study of a particularly hard debug problem on a state of the art microprocessor will demonstrate the application of the PICA method.

  2. Watching chips work: picosecond hot electron light emission from integrated circuits

    NASA Astrophysics Data System (ADS)

    Kash, J. A.; Tsang, J. C.

    2000-03-01

    The picosecond pulses of hot carrier luminescence that are observed from individual submicron FETs in CMOS circuits can be used to describe the internal operation of integrated circuits. To effectively use the weak emission pulses, we have developed a method called picosecond integrated circuit analysis (PICA) which simultaneously images and time resolves the emission. PICA has been used to characterize the operation of integrated circuits from simple ring oscillators to a full microprocessors. Examples of circuit characterization and fault diagnosis are presented.

  3. Drilling rate of five metals with picosecond laser pulses at 355, 532, and 1064 nm

    NASA Astrophysics Data System (ADS)

    Spiro, Alex; Lowe, Mary; Pasmanik, Guerman

    2012-06-01

    Experimental results on picosecond laser processing of aluminum, nickel, stainless steel, molybdenum, and tungsten are described. Hole drilling is employed for comparative analysis of processing rates in an air environment. Drilling rates are measured over a wide range of laser fluences (0.05-20 J/cm2). Experiments with picosecond pulses at 355 nm are carried out for all five metals and in addition at 532 nm, and 1064 nm for nickel. A comparison of drilling rate with 6-ps and 6-ns pulses at 355 nm is performed. The dependence of drilling rate on laser fluence measured with picosecond pulses demonstrates two logarithmic regimes for all five metals. To determine the transition from one regime to another, a critical fluence is measured and correlated with the thermal properties of the metals. The logarithmic regime at high-fluence range with UV picosecond pulses is reported for the first time. The energy efficiency of material removal for the different regimes is evaluated. The results demonstrate that UV picosecond pulses can provide comparable quality and higher processing rate compared with literature data on ablation with near-IR femtosecond lasers. A significant contribution of two-photon absorption to the ablation process is suggested to explain high processing rate with powerful UV picosecond pulses.

  4. Lung Emergencies

    MedlinePlus

    ... Emergencies Cardiac Emergencies Eye Emergencies Lung Emergencies Surgeries Lung Emergencies People with Marfan syndrome can be at ... should be considered an emergency. Symptoms of sudden lung collapse (pneumothorax) Symptoms of a sudden lung collapse ...

  5. Probing single-cell mechanics with picosecond ultrasonics.

    PubMed

    Dehoux, Thomas; Abi Ghanem, Maroun; Zouani, Omar F; Ducousso, Mathieu; Chigarev, Nikolay; Rossignol, Clément; Tsapis, Nicolas; Durrieu, Marie-Christine; Audoin, Bertrand

    2015-02-01

    The mechanical properties of cells play a key role in several fundamental biological processes, such as migration, proliferation, differentiation and tissue morphogenesis. The complexity of the inner cell composition and the intricate meshwork formed by transmembrane cell-substrate interactions demands a non-invasive technique to probe cell mechanics and cell adhesion at a subcell scale. In this paper we review the use of laser-generated GHz acoustic waves--a technique called picosecond ultrasonics (PU)--to probe the mechanical properties of single cells. We first describe applications to vegetal cells and biomimetic systems. We show how these systems can be used as simple models to understand more complex animal cells. We then present an opto-acoustic bio-transducer designed for in vivo measurements in physiological conditions. We illustrate the use of this transducer through the simultaneous probing of the density and compressibility of Allium cepa cells. Finally, we demonstrate that this technique can quantify animal-cell adhesion on metallic surfaces by analyzing the acoustic pulses reflected off the cell-metal interface. This innovative approach allows investigating quantitatively cell mechanics without fluorescent labels or mechanical contact to the cell. PMID:25172112

  6. Mapping transient electric fields with picosecond electron bunches.

    PubMed

    Chen, Long; Li, Runze; Chen, Jie; Zhu, Pengfei; Liu, Feng; Cao, Jianming; Sheng, Zhengming; Zhang, Jie

    2015-11-24

    Transient electric fields, which are an important but hardly explored parameter of laser plasmas, can now be diagnosed experimentally with combined ultrafast temporal resolution and field sensitivity, using femtosecond to picosecond electron or proton pulses as probes. However, poor spatial resolution poses great challenges to simultaneously recording both the global and local field features. Here, we present a direct 3D measurement of a transient electric field by time-resolved electron schlieren radiography with simultaneous 80-μm spatial and 3.7-ps temporal resolutions, analyzed using an Abel inversion algorithm. The electric field here is built up at the front of an aluminum foil irradiated with a femtosecond laser pulse at 1.9 × 10(12) W/cm(2), where electrons are emitted at a speed of 4 × 10(6) m/s, resulting in a unique "peak-valley" transient electric field map with the field strength up to 10(5) V/m. Furthermore, time-resolved schlieren radiography with charged particle pulses should enable the mapping of various fast-evolving field structures including those found in plasma-based particle accelerators. PMID:26554022

  7. Direct fluorescence characterisation of a picosecond seeded optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Stuart, N. H.; Bigourd, D.; Hill, R. W.; Robinson, T. S.; Mecseki, K.; Patankar, S.; New, G. H. C.; Smith, R. A.

    2015-02-01

    The temporal intensity contrast of high-power lasers based on optical parametric amplification (OPA) can be limited by parametric fluorescence from the non-linear gain stages. Here we present a spectroscopic method for direct measurement of unwanted parametric fluorescence widely applicable from unseeded to fully seeded and saturated OPA operation. Our technique employs simultaneous spectroscopy of fluorescence photons slightly outside the seed bandwidth and strongly attenuated light at the seed central wavelength. To demonstrate its applicability we have characterised the performance of a two-stage picosecond OPA pre-amplifier with 2.8×105 gain, delivering 335 μJ pulses at 1054 nm. We show that fluorescence from a strongly seeded OPA is reduced by ~500× from the undepleted to full pump depletion regimes. We also determine the vacuum fluctuation driven noise term seeding this OPA fluorescence to be 0.7±0.4 photons ps-1 nm-1 bandwidth. The resulting shot-to-shot statistics highlights a 1.5% probability of a five-fold and 0.3% probability of a ten-fold increase of fluorescence above the average value. Finally, we show that OPA fluorescence can be limited to a few-ps pedestal with 3×10-9 temporal intensity contrast 1.3 ps ahead of an intense laser pulse, a level highly attractive for large scale chirped-pulse OPA laser systems.

  8. The lartge-area picosecond photo-detector (LAPPD) project

    NASA Astrophysics Data System (ADS)

    Varner, Gary

    2012-03-01

    The technological revolution that replaced the bulky Cathode Ray Tube with a wide variety of thin, reduced-cost display technologies, has yet to be realized for photosensors. Such a low-cost, robust and flexible photon detector, capable of efficient single photon measurement with good spatial and temporal resolution, would have numerous scientific, medical and industrial applications. To address the significant technological challenges of realizing such a disruptive technology, the Large Area Picosecond Photo-Detector (LAPPD) collaboration was formed, and has been strongly supported by the Department of Energy. This group leverages the inter-disciplinary capabilities and facilities at Argonne National Laboratory, the Berkeley Space Sciences Laboratory (SSL), electronics expertise at the Universities of Chicago and Hawaii, and close work with industrial partners to extend the known technologies. Advances in theory-inspired design and in-situ photocathode characterization during growth, Atomic Layer Deposition (ALD) for revolutionizing micro-channel plate fabrication, and compact, wave-form sampling CMOS ASIC readout of micro striplines are key tools toward realizing a viable LAPPD device. Progress toward a first 8" x 8" demonstrator module will be presented.

  9. Evidence of Protein Collective Motions on the Picosecond Timescale

    PubMed Central

    He, Yunfen; Chen, J.-Y.; Knab, J.R.; Zheng, Wenjun; Markelz, A.G.

    2011-01-01

    We investigate the presence of structural collective motions on a picosecond timescale for the heme protein, cytochrome c, as a function of oxidation and hydration, using terahertz (THz) time domain spectroscopy and molecular dynamics simulations. The THz response dramatically increases with oxidation, with the largest increase for lowest hydrations, and highest frequencies. For both oxidation states the THz response rapidly increases with hydration saturating above ∼25% (g H2O/g protein). Quasiharmonic vibrational modes and dipole-dipole correlation functions were calculated from molecular dynamics trajectories. The collective mode density of states alone reproduces the measured hydration dependence, providing strong evidence of the existence of these motions. The large oxidation dependence is reproduced only by the dipole-dipole correlation function, indicating the contrast arises from diffusive motions consistent with structural changes occurring in the vicinity of buried internal water molecules. This source for the observed oxidation dependence is consistent with the lack of an oxidation dependence in nuclear resonant vibrational spectroscopy measurements. PMID:21320451

  10. Observation of neutronless fusion reactions in picosecond laser plasmas.

    PubMed

    Belyaev, V S; Matafonov, A P; Vinogradov, V I; Krainov, V P; Lisitsa, V S; Roussetski, A S; Ignatyev, G N; Andrianov, V P

    2005-08-01

    The yield of alpha particles in neutronless fusion reactions 11B +p in plasmas produced by picosecond laser pulses with the peak intensity of 2 x 10(18) W/cm2 has been observed. Experiments were carried out on the "Neodymium" laser facility at the pulse energy of 10-12 J and pulse duration of 1.5 ps. The composite targets 11B + (CH2)n were used. The yield of 10(3) alpha particles per pulse has been observed. The energy spectrum of alpha particles contains two maxima: at 3-4 MeV and at 6-10 MeV . The first of these peaks corresponds to the secondary alpha12 particles at the decay of the intermediate first excited state of 8Be, whereas the second peak demonstrates generation of alpha1 particles in the reaction 11B +p with the production of this excited state. Simultaneous measurements of neutrons result in zero yield, which proves the observation of neutronless fusion reactions in our experiments. PMID:16196717

  11. Picosecond infrared laser (PIRL): an ideal phonomicrosurgical laser?

    PubMed

    Hess, Markus; Hildebrandt, Michael Dominik; Müller, Frank; Kruber, Sebastian; Kroetz, Peter; Schumacher, Udo; Reimer, Rudolph; Kammal, Michael; Püschel, Klaus; Wöllmer, Wolfgang; Miller, Dwayne

    2013-11-01

    A comparison of tissue cutting effects in excised cadaver human vocal folds after incisions with three different instruments [scalpel, CO2 laser and the picosecond infrared laser-(PIRL)] was performed. In total, 15 larynges were taken from human cadavers shortly after death. After deep freezing and thawing for the experiment, the vocal folds suspended in the hemilarynx were incised. Histology and environmental scanning electron microscopy (ESEM) analyses were performed. Damage zones after cold instrument cuts ranged from 51 to 135 μm, as compared to 9-28 μm after cutting with the PIRL. It was shown that PIRL incision had smaller zones of tissue coagulation and tissue destruction, when compared with scalpel and CO2 laser cuts. The PIRL technology provides an (almost) atraumatic laser, which offers a quantum jump towards realistic 'micro'-phonosurgery on a factual cellular dimension, almost entirely avoiding coagulation, carbonization, or other ways of major tissue destruction in the vicinity of the intervention area. Although not available for clinical use yet, the new technique appears promising for future clinical applications, so that technical and methodological characteristics as well as tissue experiments seem worthwhile to be communicated at this stage of development. PMID:23708442

  12. Sub-picosecond optical switching with a negative index metamaterial

    SciTech Connect

    Dani, Keshav M; Upadhya, Prashant C; Zahyum, Ku

    2009-01-01

    Development of all-optical signal processing, eliminating the performance and cost penalties of optical-electrical-optical conversion, is important for continu,ing advances in Terabits/sec (Tb/s) communications.' Optical nonlinearities are generally weak, traditionally requiring long-path, large-area devicesl,2 or very high-Q, narrow-band resonator structures.3 Optical metamaterials offer unique capabilities for optical-optical interactions. Here we report 600 femtosecond (fs) all-optical modulation using a fIShnet (2D-perforated metallamorphous-Si (a-Si)/metal film stack) negative-index meta material with a structurally tunable broad-band response near 1.2 {micro}m. Over 20% modulation (experimentally limited) is achieved in a path length of only 116 nm by photo-excitation of carriers in the a-Si layer. This has the potential for Tb/s aU-optical communication and will lead to other novel, compact, tunable sub-picosecond (ps) photonic devices.

  13. Sub-picosecond Resolution Time-to-Digital Converter

    SciTech Connect

    Ph D, Vladimir Bratov; Ph D, Vladimir Katzman; MS EE, Jeb Binkley

    2006-03-30

    Time-to-digital converters with sub-picosecond resolutions are needed to satisfy the requirements of time-on-flight measurements of the next generation of high energy and nuclear physics experiments. The converters must be highly integrated, power effective, low cost, and feature plug-and-play capabilities to handle the increasing number of channels (up to hundreds of millions) in future Department of Energy experiments. Current state-off-the-art time-to-digital converter integrated circuits do not have the sufficient degree of integration and flexibility to fulfill all the described requirements. During Phase I, the Advanced Science and Novel Technology Company in cooperation with the nuclear physics division of the Oak Ridge National Laboratory has developed the architecture of a novel time-to-digital converter with multiple channels connected to an external processor through a special interfacing block and synchronized by clock signals generated by an internal phase-locked loop. The critical blocks of the system including signal delay lines and delay-locked loops with proprietary differential delay cells, as well as the required digital code converter and the clock period counter have been designed and simulated using the advanced SiGe120 BiCMOS technological process. The results of investigations demonstrate a possibility to achieve the digitization accuracy within 1ps. ADSANTEC has demonstrated the feasibility of the proposed concept in computer simulations. The proposed system will be a critical component for the next generation of NEP experiments.

  14. Mapping transient electric fields with picosecond electron bunches

    PubMed Central

    Chen, Long; Li, Runze; Chen, Jie; Zhu, Pengfei; Liu, Feng; Cao, Jianming; Sheng, Zhengming; Zhang, Jie

    2015-01-01

    Transient electric fields, which are an important but hardly explored parameter of laser plasmas, can now be diagnosed experimentally with combined ultrafast temporal resolution and field sensitivity, using femtosecond to picosecond electron or proton pulses as probes. However, poor spatial resolution poses great challenges to simultaneously recording both the global and local field features. Here, we present a direct 3D measurement of a transient electric field by time-resolved electron schlieren radiography with simultaneous 80-μm spatial and 3.7-ps temporal resolutions, analyzed using an Abel inversion algorithm. The electric field here is built up at the front of an aluminum foil irradiated with a femtosecond laser pulse at 1.9 × 1012 W/cm2, where electrons are emitted at a speed of 4 × 106 m/s, resulting in a unique “peak–valley” transient electric field map with the field strength up to 105 V/m. Furthermore, time-resolved schlieren radiography with charged particle pulses should enable the mapping of various fast-evolving field structures including those found in plasma-based particle accelerators. PMID:26554022

  15. Oscillations of absorption of a probe picosecond light pulse caused by its interaction with stimulated picosecond emission of GaAs

    NASA Astrophysics Data System (ADS)

    Ageeva, N. N.; Bronevoi, I. L.; Zabegaev, D. N.; Krivonosov, A. N.

    2015-04-01

    The self-modulation of absorption of a picosecond light pulse was observed earlier [1] in a thin (˜1-μm thick) GaAs layer pumped by a high-power picosecond pulse. Analysis of the characteristics of this self-modulation predicted [5] that the dependences of the probe pulse absorption on the pump pulse energy and picosecond delay between pump and probe pulses should be self-modulated by oscillations. Such self-modulation was experimentally observed in this work. Under certain conditions, absorption oscillations proved to be a function of part of the energy of picosecond stimulated emission of GaAs lying above a certain threshold in the region where the emission front overlapped the probe pulse front. Absorption oscillations are similar to self-modulation of the GaAs emission characteristics observed earlier [4]. This suggests that the self-modulation of absorption and emission is determined by the same type of interaction of light pulses in the active medium, the physical mechanism of which has yet to be determined.

  16. Oscillations of absorption of a probe picosecond light pulse caused by its interaction with stimulated picosecond emission of GaAs

    SciTech Connect

    Ageeva, N. N.; Bronevoi, I. L. Zabegaev, D. N.; Krivonosov, A. N.

    2015-04-15

    The self-modulation of absorption of a picosecond light pulse was observed earlier [1] in a thin (∼1-μm thick) GaAs layer pumped by a high-power picosecond pulse. Analysis of the characteristics of this self-modulation predicted [5] that the dependences of the probe pulse absorption on the pump pulse energy and picosecond delay between pump and probe pulses should be self-modulated by oscillations. Such self-modulation was experimentally observed in this work. Under certain conditions, absorption oscillations proved to be a function of part of the energy of picosecond stimulated emission of GaAs lying above a certain threshold in the region where the emission front overlapped the probe pulse front. Absorption oscillations are similar to self-modulation of the GaAs emission characteristics observed earlier [4]. This suggests that the self-modulation of absorption and emission is determined by the same type of interaction of light pulses in the active medium, the physical mechanism of which has yet to be determined.

  17. Amplified picosecond diode lasers for diffuse optical imaging and spectroscopy of tissue

    NASA Astrophysics Data System (ADS)

    Erdmann, R.; Langkopf, M.; Lauritsen, K.; Bulter, A.; Wahl, M.; Wabnitz, H.; Liebert, A.; Moller, M.; Schmitt, T.

    2005-04-01

    Optical techniques based on photon migration are rapidly emerging as a promising alternative and/or augmentation of existing medical imaging modalities. For example, real time studies of hemodynamic changes in brain tissue are possible as a step towards optical functional brain imaging. Time-resolved implementations of these techniques allow for discrimination between scattering and absorption and for depth resolution. They require sub-nanosecond pulsed light sources with high repetition rate and sufficient power for deep enough tissue penetration. Picosecond diode lasers satisfy the clinical demands of economy, compact size, and reliability almost perfectly. Today multi-channel diode laser devices are commercially available and are widely used in diffuse optical imaging and spectroscopy, in particular in optical tomography and breast cancer detection. However, the output powers of these devices are just about sufficient for moderate tissue penetration depths. An improvement that does not compromise the advantages of the diode laser sources is amplification of the diode laser output by means of solid state tapered amplifiers. We present an amplified light source for use in NIR diffuse optical spectroscopy and imaging, providing pulse widths as short as 100 ps, adjustable repetition rates up to 80 MHz, and peak power levels as high as 7 Watts, corresponding to average power levels exceeding 100 mW. In combination with time-resolved photon counting electronics matching the high throughput demands in conjunction with the new source, state-of-the-art systems for diffuse optical imaging can be built. System design features and possible application examples are presented.

  18. Eye Emergencies

    MedlinePlus

    ... Emergencies Cardiac Emergencies Eye Emergencies Lung Emergencies Surgeries Eye Emergencies Marfan syndrome significantly increases your risk of ... light-sensitive membrane in the back of the eye (the retina) from its supporting layers. It is ...

  19. Picosecond Spectroscopy of Reactive Intermediates: Generation and Dynamics of Arylmethyl Ions and Radicals in Solution.

    NASA Astrophysics Data System (ADS)

    Schmidt, Jeffrey Allan

    A detailed experimental description is presented of a practical and relatively inexpensive approach for two simultaneous and independent types of picosecond spectroscopic measurements. Two data collection subsystems, (1) a picosecond pump-probe transient absorption/emission spectrometer and (2) a streak camera system for time-dependent measurements of absorption and emission, were developed as independent subsystems within an integrated system based on a single mode-locked Nd:YAG laser which concurrently supplies each subsystem with picosecond pulses. Considerations concerning electrical and optical interfacing between the two subsystems are discussed. With these two subsystems, picosecond-pulsed photolyses of diphenylmethyl chloride, diphenylmethyl bromide, triphenylmethyl chloride, triphenylmethyl bromide, and triphenylacetyl chloride in acetonitrile, methylene chloride, and cyclohexane were studied. The dependence of the yields of radicals and ions are discussed with respect to the nature of the starting compound and the solvent. Ion-pair dynamics were monitored with subsystems 1 and 2. Microscopic rate constants for the collapse of the contact ion pair (CIP), separation of the CIP, and reformation of the CIP from the separated ions were calculated. The photophysics and photochemistry of the triphenylmethyl radical generated from triphenylmethyl chloride, and triphenylacetyl chloride, and tert-butyl triphenylperacetate in solution were studied by means of a unique three-pulse picosecond transient absorption technique. The emission lifetime of the excited triphenylmethyl radical was measured as a function of solvent polarity with subsystem 2. These data were collectively used to gain an understanding of the electronically excited triphenylmethyl radical.

  20. Cell stimulation and calcium mobilization by picosecond electric pulses.

    PubMed

    Semenov, Iurii; Xiao, Shu; Kang, Dongkoo; Schoenbach, Karl H; Pakhomov, Andrei G

    2015-10-01

    We tested if picosecond electric pulses (psEP; 190 kV/cm, 500 ps at 50% height), which are much shorter than channel activation time, can activate voltage-gated (VG) channels. Cytosolic Ca(2+) was monitored by Fura-2 ratiometric imaging in GH3 and NG108 cells (which express multiple types of VG calcium channels, VGCC), and in CHO cells (which express no VGCC). Trains of up to 100 psEP at 1 kHz elicited no response in CHO cells. However, even a single psEP significantly increased Ca(2+) in both GH3 (by 114 ± 48 nM) and NG108 cells (by 6 ± 1.1 nM). Trains of 100 psEP amplified the response to 379 ± 33 nM and 719 ± 315 nM, respectively. Ca(2+) responses peaked within 2-15s and recovered for over 100 s; they were 80-100% inhibited by verapamil and ω-conotoxin, but not by the substitution of Na(+) with N-methyl-D-glucamine. There was no response to psEP in Ca(2+)-free medium, but adding external Ca(2+) even 10s later evoked Ca(2+) response. We conclude that electrical stimuli as short as 500 ps can cause long-lasting opening of VGCC by a mechanism which does not involve conventional electroporation, heating (which was under 0.06 K per psEP), or membrane depolarization by opening of VG Na(+) channels. PMID:26011130

  1. Picosecond laser cutting and drilling of thin flex glass

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, Krystian L.; Brunton, Adam; Rumsby, Phil; Hand, Duncan P.

    2016-03-01

    We investigate the feasibility of cutting and drilling thin flex glass (TFG) substrates using a picosecond laser operating at wavelengths of 1030 nm, 515 nm and 343 nm. 50 μm and 100 μm thick AF32®Eco Thin Glass (Schott AG) sheets are used. The laser processing parameters such as the wavelength, pulse energy, pulse repetition frequency, scan speed and the number of laser passes which are necessary to perform through a cut or to drill a borehole in the TFG substrate are studied in detail. Our results show that the highest effective cutting speeds (220 mm/s for a 50 μm thick TFG substrate and 74 mm/s for a 100 μm thick TFG substrate) are obtained with the 1030 nm wavelength, whereas the 343 nm wavelength provides the best quality cuts. The 515 nm wavelength, meanwhile, can be used to provide relatively good laser cut quality with heat affected zones (HAZ) of <25 μm for 50 μm TFG and <40 μm for 100 μm TFG with cutting speeds of 100 mm/s and 28.5 mm/s, respectively. The 343 nm and 515 nm wavelengths can also be used for drilling micro-holes (with inlet diameters of ⩽75 μm) in the 100 μm TFG substrate with speeds of up to 2 holes per second (using 343 nm) and 8 holes per second (using 515 nm). Optical microscope and SEM images of the cuts and micro-holes are presented.

  2. An investigation on the hole quality during picosecond laser helical drilling of stainless steel 304

    NASA Astrophysics Data System (ADS)

    Zhang, Hongyu; Di, Jianke; Zhou, Ming; Yan, Yu; Wang, Rong

    2015-05-01

    Precision drilling with ultra-short pulse lasers (e.g., picosecond and femtosecond) has been advocated to significantly improve the quality of the micro-holes with reduced recast layer thickness and no heat-affected zone. However, a combination of high-power picosecond laser with helical drilling strategy in laser drilling has rarely been reported in previous studies. In the present study, a series of micro-holes with circular, triangular, rectangular, and rhombic shapes (diameter 0.6 mm) were manufactured on stainless steel 304 using a newly developed laser drilling system which incorporated a picosecond laser and a high-speed laser beam rotation apparatus into a five-axis positioning platform. The quality of the helical drilled holes, e.g., recast layer, micro-crack, circularity, and conicity, were evaluated using an optical microscope, an optical interferometer, and a scanning electron microscope. In addition, the microstructure of the samples was investigated following etching treatment. It was demonstrated that the entrance ends, the exit ends, and the side walls of the micro-holes were quite smooth without accumulation of spattering material and formation of recast layer and micro-crack. No tapering phenomenon was observed, and the circularity of the holes was fairly good. There was no distinctive difference with regard to the microstructure between the edges of the holes and the bulk material. Picosecond laser helical drilling can be an effective technique for manufacturing of micro-holes with very high quality. The development of high-power picosecond laser would promote picosecond laser drilling to be more industrial relevance in the future.

  3. Elemental fractionation in 785 nm picosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-05-01

    Elemental fractionation and ICP-MS signal response were investigated for two different pulse width laser beams originating from the same laser system. Femtosecond and picosecond laser beams at pulse widths of 130 fs and 110 ps, respectively, and wavelength of 785 nm were used to ablate NIST 610 synthetic glass and SRM 1107 Naval Brass B at the same spot for 800 to 1000 laser pulses at different repetition rates (5 to 50 Hz). Elemental fractionation was found to depend on repetition rate and showed a trend with femtosecond laser ablation that is opposite to that observed in picosecond laser ablation for most measured isotopes. ICP-MS signal intensity was higher in femtosecond than picosecond LA-ICP-MS in both NIST 610 and naval brass when ablation was conducted under the same fluence and repetition rate. The differences in signal intensity were partly related to differences in particle size distribution between particles generated by femtosecond and picosecond laser pulses and the consequent differences in transport and ionization efficiencies. The main reason for the higher signal intensity resulting from femtosecond laser pulses was related to the larger crater sizes compared to those created during picosecond laser ablation. Elemental ratios measured using 66Zn/63Cu, 208Pb/238U, 232Th/238U, 66Zn/232Th and 66Zn/208Pb were found to change with the number of laser pulses with data points being more scattered in picosecond than femtosecond laser pulses. Reproducibility of replicate measurements of signal intensities, fractionation and elemental ratios was better for fs-LA-ICP-MS (RSD ~ 3 to 6%) than ps-LA-ICP-MS (RSD ~ 7 to 11%).

  4. Solid-state NMR approaches to internal dynamics of proteins: from picoseconds to microseconds and seconds.

    PubMed

    Krushelnitsky, Alexey; Reichert, Detlef; Saalwächter, Kay

    2013-09-17

    Solid-state nuclear magnetic resonance (NMR) spectroscopy has matured to the point that it is possible to determine the structure of proteins in immobilized states, such as within microcrystals or embedded in membranes. Currently, researchers continue to develop and apply NMR techniques that can deliver site-resolved dynamic information toward the goal of understanding protein function at the atomic scale. As a widely-used, natural approach, researchers have mostly measured longitudinal (T1) relaxation times, which, like in solution-state NMR, are sensitive to picosecond and nanosecond motions, and motionally averaged dipolar couplings, which provide an integral amplitude of all motions with a correlation time of up to a few microseconds. While overall Brownian tumbling in solution mostly precludes access to slower internal dynamics, dedicated solid-state NMR approaches are now emerging as powerful new options. In this Account, we give an overview of the classes of solid-state NMR experiments that have expanded the accessible range correlation times from microseconds to many milliseconds. The measurement of relaxation times in the rotating frame, T1ρ, now allows researchers to access the microsecond range. Using our recent theoretical work, researchers can now quantitatively analyze this data to distinguish relaxation due to chemical-shift anisotropy (CSA) from that due to dipole-dipole couplings. Off-resonance irradiation allows researchers to extend the frequency range of such experiments. We have built multidimensional analogues of T2-type or line shape experiments using variants of the dipolar-chemical shift correlation (DIPSHIFT) experiment that are particularly suited to extract intermediate time scale motions in the millisecond range. In addition, we have continuously improved variants of exchange experiments, mostly relying on the recoupling of anisotropic interactions to address ultraslow motions in the ms to s ranges. The NH dipolar coupling offers a

  5. A diffusion model for picosecond electron bunches from negative electron affinity GaAs photo cathodes

    SciTech Connect

    P. Hartmann; J. Bermuth; D. v. Harrach; J. Hoffmann; S. Kobis; E. Reichert; K. Aulenbacher; J. Schuler; M. Steigerwald

    1998-10-27

    Even though theoretical estimates predict response times for the photo emission process of electrons from a negative electron affinity GaAs photo emitter in excess of hundreds of picoseconds, recent measurements found electron bunch durations of 40 ps or less. This work presents precise measurements of picosecond electron bunches from a negative affinity bulk GaAs photo cathode and develops a model which explains the measured bunch durations as well as the observed bunch shapes. The bunch shape turns out to be independent from the quantum efficiency of the photo emitter.

  6. Laser ablation of CFRP using picosecond laser pulses at different wavelengths from UV to IR

    NASA Astrophysics Data System (ADS)

    Wolynski, Alexander; Herrmann, Thomas; Mucha, Patrick; Haloui, Hatim; L'huillier, Johannes

    Laser processing of carbon fibre reinforced plastics (CFRP) has a great industrial relevance for high performance structural parts in airplanes, machine tools and cars. Through-holes drilled by nanosecond laser pulses show thermal induced molten layers and voids. Recently, picosecond lasers have demonstrated the ability to drill high-efficient and high-quality rivet through-holes. In this paper a high-power picosecond laser system operating at different wavelengths (355 nm, 532 nm and 1064 nm) has been used for CFRP ablation experiments to study the influence of different laser parameters in terms of machining quality and processing time.

  7. Production of picosecond, kilojoule, and petawatt laser pulses via Raman amplification of nanosecond pulses.

    PubMed

    Trines, R M G M; Fiúza, F; Bingham, R; Fonseca, R A; Silva, L O; Cairns, R A; Norreys, P A

    2011-09-01

    Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump pulse to probe pulse, implying that multikilojoule ultraviolet petawatt laser pulses can be produced using this scheme. This has important consequences for the demonstration of fast-ignition inertial confinement fusion. PMID:21981507

  8. Picosecond kinetic absorption and fluorescence studies of bovine rhodopsin with a fixed 11-ene.

    PubMed Central

    Buchert, J; Stefancic, V; Doukas, A G; Alfano, R R; Callender, R H; Pande, J; Akita, H; Balogh-Nair, V; Nakanishi, K

    1983-01-01

    A synthetic retinal having a fixed 11-cis geometry has been used to prepare a nonbleachable analogue of bovine rhodopsin. Marked differences in the picosecond absorption and fluorescence behavior of this analogue at room temperature, compared with that of natural rhodopsin, were observed. This not only indicates that the 11-cis to trans isomerization of the retinal moiety is the crucial primary event in the photolysis of rhodopsin, but also it establishes that this isomerization must occur on the picosecond time scale or faster. PMID:6626668

  9. Highly efficient picosecond degenerate four-wave mixing in a tellurite microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Hoang Tuan, Tong; Kawamura, Harutaka; Nagasaka, Kenshiro; Suzuki, Takenobu; Ohishi, Yasutake

    2016-06-01

    Wavelength-tunable picosecond degenerate four-wave mixing was demonstrated in a tellurite microstructured optical fiber (TMOF). The zero-dispersion wavelength of the TMOF was shifted to 1570 nm by introducing a single ring of air holes in the cladding. The anti-Stokes signal sideband can be generated from 1490 to 1500 nm, and the Stokes idler sideband can emit from 1595 to 1645 nm. Because of the high nonlinearity of the TMOF and the large peak power of the picosecond pump, a maximal signal gain of 31.2 dB and an idler conversion efficiency of +35 dB were achieved.

  10. Picosecond supercontinuum laser with consistent emission parameters over variable repetition rates from 1 to 40 MHz

    NASA Astrophysics Data System (ADS)

    Schönau, Thomas; Siebert, Torsten; Härtel, Romano; Klemme, Dietmar; Lauritsen, Kristian; Erdmann, Rainer

    2013-02-01

    An freely triggerable picosecond visible supercontinuum laser source is presented that allows for a uniform spectral profile and equivalent pulse characteristics over variable repetition rates from 1 to 40MHz. The system features PM Yb3+-doped fiber amplification of a picosecond gain-switched seed diode at 1062 nm. The pump power in the multi-stage amplifier is actively adjusted by a microcontroller for a consistent peak power of the amplified signal in the full range of repetition rates. The length of the PCF is scaled to deliver a homogeneous spectrum and minimized distortion of the temporal pulse shape.

  11. Relativistic theory for picosecond time transfer in the vicinity of Earth

    NASA Technical Reports Server (NTRS)

    Petit, G.; Wolf, P.

    1994-01-01

    The problem of light propagation is treated in a geocentric reference system with the goal of ensuring picosecond accuracy for time transfer techniques using electromagnetic signals in the vicinity of the Earth. We give an explicit formula for a one way time transfer, to be applied when the spatial coordinates of the time transfer stations are known in a geocentric reference system rotating with the Earth. This expression is extended, at the same accuracy level of one picosecond, to the special cases of two way and LASSO time transfers via geostationary satellites.

  12. Picosecond intersubband hole relaxation in p-type quantum wells

    SciTech Connect

    Xu, Z.; Fauchet, P.M.; Rella, C.W.; Schwettman, H.A.

    1995-12-31

    We report the first direct measurement of the relaxation time of holes in p-type quantum wells using tunable, subpicosecond mid-infrared laser pulses in a pump-probe arrangement. The QW layers consisted of 50 In{sub 0.5}Ga{sub 0.5}As/Al{sub 0.5}Ga{sub 0.5}As periods. The In{sub 0.5}Ga{sub 0.5}As well was 4 nm wide and the Al{sub 0.5}Ga{sub 0.5}As barrier was 8 nm wide. The dopant concentration was 10{sup 19} CM{sup -3} which corresponds to a sheet density of 1.2 x 10{sup 13} CM{sup -2}. The room temperature IR spectrum showed a 50 meV wide absorption peak at 5.25 {mu}m (220 meV). This energy agrees with the calculated n=1 heavy hole to n=1 light hole transition energy of 240 meV (150 meV for strain and 90 meV for confinement). The large absorption width results from hole-hole scattering and the difference in dispersion relations between the two subbands. The equal-wavelength pump-probe transmission measurements were performed using the Stanford free electron laser (FEL). The FEL pulses were tuned between 4 and 6 {mu} m and their duration was less than 1 ps. The measurements were performed as a function of temperature, pump wavelength and intensity (from 0.3 to 10 GW/cm{sup 2}). In all our experiments, we find an increase of transmission (decrease of absorption or bleaching) following photopumping, which recovers as a single exponential with a time constant (relaxation time) of the order of 1 picosecond. The maximum change in transmission is linear with pump 2 intensity below 1 GW/cm{sup 2} and saturates to {approximately}3% with a saturation intensity I{sub sat} of 3 GW/cm{sup 2}. As the saturation regime is entered, the relaxation time increases from 0.8 ps to 1.8 ps. This relaxation time depends on the temperature T: it increases from 0.8 ps to 1.3 ps as T decreases from 300 K to 77 K. Finally, when we tune the laser through the absorption band, the magnitude of the signal changes but its temporal behavior does not change, within the accuracy of the measurements.

  13. Electronics for a Picosecond Time-of-flight Measurement

    SciTech Connect

    Brandt, Andrew Gerhart; Rijssenbeek, Michael

    2014-11-03

    TITLE: Electronics for a Picosecond Time-of-flight Measurement ABSTRACT: Time-of-flight (TOF) detectors have historically been used as part of the particle identification capability of multi-purpose particle physics detectors. An accurate time measurement, combined with a momentum measurement based on the curvature of the track in a magnetic field, is often sufficient to determine the particle's mass, and thus its identity. Such detectors typically have measured the particle flight time extremely precisely, with an uncertainty of one hundred trillionths of a second (also referred to as 100 picoseconds). To put this in perspective it would be like counting all the people on the Earth and getting it right within 1 person! Another use of TOFs is to measure the vertex of the event, which is the location along the beam line where the incoming particles (typically protons) collide. This vertex positon is a well measured quantity for events where the protons collide “head on” as the outgoing particles produced when you blast the proton apart can be used to trace back to a vertex point from which they originated. More frequently the protons just strike a glancing blow and remain intact—in this case they are nearly parallel to the beam and you cannot tell their vertex without this ability to precisely measure the time of flight of the protons. Occasionally both happen in the same event, that is, a central system and two protons are produced. But are they from the same collision, or just a boring background where more than one collision in the same bunch crossing conspire to fake the signal of interest? That’s where the timing of the protons comes into play. The main idea is to measure the time it takes for the two protons to reach TOF detectors positioned equidistant from the center of the main detector. If the vertex is displaced to one side than that detector will measure a shorter time while the other side detector will measure a correspondingly longer time

  14. Applications using a Picosecond 14.7 nm X-Ray Laser

    SciTech Connect

    Dunn, J; Smith, R F; Nilsen, J; Shlyaptsev, V N; Filevich, J; Rocca, J J; Marconi, M C

    2001-09-21

    We report recent application experiments on the LLNL COMET tabletop facility using the picosecond, 14.7 nm Ni-like Pd x-ray laser. This work includes measurements of a laser-produced plasma density profile with a diffraction grating interferometer.

  15. Diode-pumped solid state laser sources of picosecond UV pulses for photobiology

    NASA Astrophysics Data System (ADS)

    Roisse, Eric; Louradour, Frederic; Couderc, Vincent; Barthelemy, Alain; Gaignet, M.; Balembois, Francois; Georges, Patrick M.; Brun, Alain

    1998-05-01

    We realized three different configurations for the production of picoseconds pulses in the UV by a diode-pumped solid-state laser. The first one is based on a diode-pumped Cr:LiSAF oscillator delivering tunable picosecond pulses in the near infrared. A Ti:Sapphire regenerative amplifier increased IR pulses energy up to 4.5 (mu) J. After doubling and tripling in two LBO crystals, we obtained pulses with an energy up to 0.14 (mu) J tunable between 273 and 286 nm. In the second scheme, based on a modelocked Nd:YAG laser, the SHG (KTP) and SFG (LBO) crystals are both inserted inside the cavity. The laser operated in a Q-switched mode-locked regime and produced 1.2 mW of UV average power in pulse of 60 picoseconds duration and 4 W peak power. In the last architecture, we used a resonant enhancement with a ring- cavity. We obtained 54% conversion efficiency in the green for picoseconds pulses at 1064 nm at 100 MHz rep. rate. A special arrangement was implemented for compensation of the birefringence and walk-off of the KTP crystal in the resonant cavity. Conversion to UV in the same cavity is in progress.

  16. PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics

    SciTech Connect

    Garanin, S G; Bel'kov, S A; Rogozhnikov, G S; Rukavishnikov, N N; Romanov, V V; Voronich, I N; Vorob'ev, N S; Gornostaev, P B; Lozovoi, V I; Shchelev, M Ya

    2014-08-31

    A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 10{sup 3}) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 – 1.5 ps. (extreme light fields and their applications)

  17. Picosecond pulses produced by mode locking a Nd:glass laser with Kodak dye number26

    SciTech Connect

    Schiller, N.H.; Foresti, M.; Alfano, R.R.

    1985-05-01

    Kodak dye number26 was used to generate picosecond laser pulses by mode locking a Nd:glass laser. The intensity profiles and characteristics of the pulses were compared with those of pulses emitted using dyes number5 and number9860.

  18. Surface displacement measured by beam distortion detection technique: Application to picosecond ultrasonics

    SciTech Connect

    Chigarev, N.; Rossignol, C.; Audoin, B.

    2006-11-15

    A sensitive technique of surface displacement measurement without interferometry is proposed for the goals of picosecond ultrasonics. Simple description of detection mechanism is provided on the basis of paraxial approximation of light diffraction. Test experiments with gold and tungsten layers have been performed and analyzed. The efficiency of the technique is compared with interferometry and reflectometry methods.

  19. Reactor for boron fusion with picosecond ultrahigh power laser pulses and ultrahigh magnetic field trapping

    NASA Astrophysics Data System (ADS)

    Miley, G. H.; Hora, H.; Kirchhoff, G.

    2016-05-01

    Compared with the deuterium tritium (DT) fusion, the environmentally clean fusion of protons with 11B is extremely difficult. When instead of nanosecond laser pulses for thermal-ablating driven ignition, picosecond pulses are used, a drastic change by nonlinearity results in ultrahigh acceleration of plasma blocks. This radically changes to economic boron fusion by a measured new avalanche ignition.

  20. Fluorescence and picosecond laser photolysis studies on the deactivation processes of excited hydrogen bonding systems

    NASA Astrophysics Data System (ADS)

    Ikeda, Noriaka; Okada, Tadashi; Mataga, Noboru

    1980-01-01

    The fluorescence quenching reaction of 2-naphthylamine and 1-pyrenol due to hydrogen bonding interaction with pyndine has been investigated Absorption spectra due to the state formed by charge transfer from excited naphthylamine to hydrogen bonded pyridine have been observed by means of picosecond laser photolysis.

  1. Amplitude and polarization instability of picosecond light pulses exciting a semiconductor optical resonator.

    PubMed

    Markarov, V A; Pershin, S M; Podshivalov, A A; Zadoian, R S; Zheludev, N I

    1983-11-01

    The first results of our study of nonlinear shift, distortion of form, and destruction of picosecond light pulses interacting with a nonlinear Fabry-Perot resonator in a strongly nonstationary regime are reported. Polarization instability of the light pulse transmitted through a nonlinear resonator has been observed. PMID:19718182

  2. PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics

    NASA Astrophysics Data System (ADS)

    Garanin, S. G.; Bel'kov, S. A.; Rogozhnikov, G. S.; Rukavishnikov, N. N.; Romanov, V. V.; Voronich, I. N.; Vorob'ev, N. S.; Gornostaev, P. B.; Lozovoi, V. I.; Shchelev, M. Ya

    2014-08-01

    A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 103) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 - 1.5 ps.

  3. Picosecond excite-and-probe absorption measurement of the 4T2 state nonradiative lifetime in ruby

    NASA Technical Reports Server (NTRS)

    Gayen, S. K.; Wang, W. B.; Petricevic, V.; Dorsinville, R.; Alfano, R. R.

    1985-01-01

    In a picosecond excite-and-probe absorption measurement, a 527-nm picosecond pulse excites the 4T2 state of the Cr(3+) ion in ruby and a 3.4-micron picosecond probe pulse monitors the growth and decay of population in the 2E state as a function of pump-probe delay. From the growth of population in the metastable 2E state, an upper limit of 7 ps for the nonradiative lifetime of the 4T2 state is determined.

  4. Study of solvation dynamics in the interior of staphylococcal nuclease (SNase) using picosecond-resolved emission spectra of tryptophan

    NASA Astrophysics Data System (ADS)

    Gao, Guangyu; Li, Yu; Wang, Wei; Men, Jing; Zhong, Dongping; Wang, ShuFeng; Gong, Qihuang

    2014-09-01

    We report here our study on ultrafast spectral dynamics in the interior of SNase using picosecond-resolved emission spectra of tryptophan through site-directed mutagenesis. By probing the solvation dynamics in the nucleotide binding pocket and the Ca2+ binding pocket as well as in the interior of hydrophobic core, two robust relaxation time scales on a few picoseconds and on tens of picoseconds have been observed. Both two time scales are strongly correlated with local structural and chemical properties of protein. These distinct differences in solvation dynamics reflect the intimate relationship between the dynamic structures and the functions of enzyme.

  5. The First Picosecond after Sunlight Absorption in Si, GaAs, and CdTe from First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Bernardi, Marco; Neaton, Jeffrey B.; Louie, Steven G.

    2014-03-01

    Sunlight absorption in semiconducting materials generates out-of-equilibrium electron populations - also known as hot carriers - relaxing towards equilibrium through a host of scattering processes at the subpicosecond time scale. While such dissipation processes typically result in the loss of more than half of the energy associated with the absorbed sunlight, a microscopic understanding of this ultrafast regime is still missing. In this talk, we provide a detailed picture of the first picosecond after sunlight absorption in semiconductors of wide use in photovoltaics (PV) such as Si, GaAs, and CdTe. Our results are based on ab initio calculations combining density functional theory and the GW plus Bethe-Salpeter Equation (GW-BSE) approach together with electron-phonon interactions. We computed the lifetimes and k-space dependence of electron-electron and electron-phonon scattering events responsible for ultrafast solar energy dissipation. Using this information, we simulated the ultrafast dynamics of hot carriers using an empirical-parameter-free formulation of the Boltzmann equation. A clear understanding of hot carrier dynamics emerges for several materials of interest in PV, and novel engineering paradigms are suggested.

  6. Emergency Contraception

    MedlinePlus

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  7. Chemical Emergency

    MedlinePlus

    ... Emergency App Find our Emergency App in the Apple Store or Google Play Aplicación de Emergencias - ahora ... Lifesaving Blood Get Assistance Types of Emergencies Be Red Cross Ready Mobile Apps Workplaces & Organizations Resources For ...

  8. High-power picosecond laser drilling/machining of carbon fibre-reinforced polymer (CFRP) composites

    NASA Astrophysics Data System (ADS)

    Salama, A.; Li, L.; Mativenga, P.; Sabli, A.

    2016-02-01

    The large differences in physical and thermal properties of the carbon fibre-reinforced polymer (CFRP) composite constituents make laser machining of this material challenging. An extended heat-affected zone (HAZ) often occurs. The availability of ultrashort laser pulse sources such as picosecond lasers makes it possible to improve the laser machining quality of these materials. This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system. Small HAZs (<25 µm) were obtained on the entry side of 6-mm-diameter hole drilled on sample of 6 mm thickness, whereas no HAZ was seen below the top surface on the cut surfaces. Multiple ring material removal strategy was used. Furthermore, the effect of laser processing parameters such as laser power, scanning speed and repetition rate on HAZ sizes and ablation depth was investigated.

  9. Picosecond soft-x-ray source from subpicosecond laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Workman, J.; Maksimchuk, A.; Liu, X.; Ellenberger, U.; Coe, J. S.; Chien, C.-Y.; Umstadter, D.

    1996-01-01

    Short-pulse high-intensity laser-plasma interactions are investigated experimentally with temporally and spectrally resolved soft-x-ray diagnostics. We demonstrate that, by adjustment of the incident laser flux, the pulse width of the laser-produced x rays emitted from solid targets may be varied to as short as the picosecond time scale. Bright, picosecond, broadband emission characteristic of a short-scale-length high-density plasma is produced only when a high laser contrast (1010) is used. The results are found to be in qualitative agreement with both the predictions of a simple model of radiation from a collisionally dominated atomic system and the results obtained from a numerical simulation. 52.40.Nk.

  10. Picosecond circular dichroism spectroscopy: experiment, theory, and applications to protein dynamics

    NASA Astrophysics Data System (ADS)

    Xie, Sunney; Simon, John D.

    1990-05-01

    An experimental technique for measuring time dependent circular dichroism signals with picosecond resolution is described. The details of the experimental apparatus are presented. Theoretical modeling of the detected signal demonstrates that the circular dichroism signal can be isolated from contributions due to pump-induced linear dichroism and linear birefringence effects. The experimental apparatus is used to examine the comformation relaxation in myoglobin following the photoelimination of CO from carbonmonoxymyoglobin. Probing the circular dichroism of the N-band of the herne at 355 nm reveals a relaxation of several hundreds of picosecond, over two orders of magnitude slower than the photo-induced bond cleavage. These results are discussed in terms of the restructuring of the protein following photodissociation.

  11. Filamentation and supercontinuum generation in solid-state dielectric media with picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Galinis, J.; Tamošauskas, G.; GražulevičiÅ«tÄ--, I.; KeblytÄ--, E.; Jukna, V.; Dubietis, A.

    2015-09-01

    Filamentation and supercontinuum generation with 1.3-ps, 1055-nm laser pulses in YAG crystal is investigated numerically and experimentally. Numerical simulations based on solving the unidirectional nonparaxial propagation equation uncover that the self-focusing dynamics of a picosecond laser pulse markedly differs from that observed in a femtosecond filamentation regime. We show that spatiotemporal transformation of the picosecond pulse is governed by the free electron plasma, which defocuses and absorbs its rear part, resulting in the formation of several subpulses of femtosecond duration, which thereafter undergo peculiar spatiotemporal dynamics and have different contributions to spectral superbroadening. The numerical findings are confirmed experimentally by measuring the spatiotemporal intensity profiles of the wave packet at various stages of propagation where relevant events of the spectral broadening occur.

  12. Quantitative phase retrieval with picosecond X-ray pulses from the ATF Inverse Compton Scattering source

    SciTech Connect

    Endrizzi, M.; Pogorelsky, I.; Gureyev, T.E.; Delogu, P.; Oliva, P.; Golosio, B.; Carpinelli, M.; Yakimenko, Y.; Bottigli, U.

    2011-01-28

    Quantitative phase retrieval is experimentally demonstrated using the Inverse Compton Scattering X-ray source available at the Accelerator Test Facility (ATF) in the Brookhaven National Laboratory. Phase-contrast images are collected using in-line geometry, with a single X-ray pulse of approximate duration of one picosecond. The projected thickness of homogeneous samples of various polymers is recovered quantitatively from the time-averaged intensity of transmitted X-rays. The data are in good agreement with the expectations showing that ATF Inverse Compton Scattering source is suitable for performing phase-sensitive quantitative X-ray imaging on the picosecond scale. The method shows promise for quantitative imaging of fast dynamic phenomena.

  13. Picosecond spectral coherent anti-Stokes Raman scattering imaging with principal component analysis of meibomian glands

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Yu; Suhalim, Jeffrey L.; Nien, Chyong Ly; Miljković, Miloš D.; Diem, Max; Jester, James V.; Potma, Eric. O.

    2011-02-01

    The lipid distribution in the mouse meibomian gland was examined with picosecond spectral anti-Stokes Raman scattering (CARS) imaging. Spectral CARS data sets were generated by imaging specific localized regions of the gland within tissue sections at consecutive Raman shifts in the CH2 stretching vibrational range. Spectral differences between the location specific CARS spectra obtained in the lipid-rich regions of the acinus and the central duct were observed, which were confirmed with a Raman microspectroscopic analysis, and attributed to meibum lipid modifications within the gland. A principal component analysis of the spectral data set reveals changes in the CARS spectrum when transitioning from the acini to the central duct. These results demonstrate the utility of picosecond spectral CARS imaging combined with multivariate analysis for assessing differences in the distribution and composition of lipids in tissues.

  14. Raman linewidth measurements using time-resolved hybrid picosecond/nanosecond rotational CARS.

    PubMed

    Nordström, Emil; Hosseinnia, Ali; Brackmann, Christian; Bood, Joakim; Bengtsson, Per-Erik

    2015-12-15

    We report an innovative approach for time-domain measurements of S-branch Raman linewidths using hybrid picosecond/nanosecond pure-rotational coherent anti-Stokes Raman spectroscopy (RCARS). The Raman coherences are created by two picosecond excitation pulses and are probed using a narrow-band nanosecond pulse at 532 nm. The generated RCARS signal contains the entire coherence decay in a single pulse. By extracting the decay times of the individual transitions, the J-dependent Raman linewidths can be calculated. Self-broadened S-branch linewidths for nitrogen and oxygen at 293 K and ambient pressure are in good agreement with previous time-domain measurements. Experimental considerations of the approach are discussed along with its merits and limitations. The approach can be extended to a wide range of pressures and temperatures and has potential for simultaneous single-shot thermometry and linewidth determination. PMID:26670495

  15. Analyzing integrated circuits at work with a picosecond time-gated imager.

    PubMed

    Comelli, D; D'Andrea, C; Valentini, G; Cubeddu, R; Casiraghi, R; Cantarelli, D

    2005-12-12

    A system based on a picosecond time-gated image intensifier is proposed for non-contact testing of CMOS circuits. The apparatus allows one to record the temporal evolution of the luminescence emitted during transistor switching as a function of the position inside the chip. The system is characterized by an intrinsic parallelism in the spatial dimensions. This feature is noticeable for studying wide sections of complex circuits, like microprocessors and random access memories, where multiple electrical events occur simultaneously. Experiments on a CMOS inverter chain and on a static memory have been carried out, in order to demonstrate the applicability of a picosecond time-gated imager to circuit analysis. PMID:19503220

  16. Quantum-chemical and picosecond investigations of excited states of thioindigoid dyes

    SciTech Connect

    Fabian, Yu.; Krysanov, S.A.; Alfimov, M.V.

    1987-11-01

    The thioindigoid dyes are convenient objects for studying reverse trans-cis photoisomerization. This is due to the extensive use of nanosecond photolysis. In this work, in order to interpret some new absorption bands, the authors compare the results of quantum-chemical and picosecond investigations of solutions of the trans isomers of thioindigo and a perinaphthothioindigoid dye. A double-beam optical system, which makes it possible to record the kinetics of the variation of the induced absorption in the range from several picoseconds to 5 nsec, was used for the real-time scanning of the continuum instead of an echelon. The spectroscopic properties of the thioindigoid chromophore can be understood in the framework of standard calculations by the Pariser-Parr-Pople method.

  17. Amplification of picosecond pulses in a 140-GHz gyrotron-traveling wave tube.

    PubMed

    Kim, H J; Nanni, E A; Shapiro, M A; Sirigiri, J R; Woskov, P P; Temkin, R J

    2010-09-24

    An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro-TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE₀₆ mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing by the finite gain bandwidth of 1.2 GHz. Experimental results taken over a wide range of parameters show good agreement with a theoretical model in the small signal gain regime. These results show that in order to limit the pulse broadening effect in gyrotron amplifiers, it is crucial to both choose an operating frequency at least several percent above the cutoff of the waveguide circuit and operate at the center of the gain spectrum with sufficient gain bandwidth. PMID:21230783

  18. Picosecond laser-induced breakdown at 5321 and 5347 A - Observation of frequency-dependent behavior

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

    1977-01-01

    A study is presented of picosecond laser-induced breakdown at 3547 and 5321 A of several materials. The thresholds obtained for breakdown at 5321 A are compared to previous results obtained at 1.064 microns using the same laser system. This comparison illustrates the transition of bulk laser-induced breakdown as it becomes increasingly frequency dependent. UV picosecond pulses are obtained by mixing 5321 A and 1.064 micron pulses in a KH2PO4 crystal. Upper and lower bounds on the 3547 A breakdown threshold are defined, although some effects of walk-off distortion and self-focusing are observed. The results are discussed with reference to models for the intrinsic processes involved in the breakdown, i.e., avalanche and multiphoton ionization.

  19. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation

    SciTech Connect

    Maxwell, Timothy John

    2012-01-01

    Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.

  20. High-voltage picosecond photoconductor switch based on low-temperature-grown GaAs

    NASA Technical Reports Server (NTRS)

    Frankel, Michael Y.; Whitaker, John F.; Mourou, Gerard A.; Smith, Frank W.; Calawa, Arthur R.

    1990-01-01

    A GaAs material grown by molecular beam epitaxy at a low substrate temperature was used to fabricate a photoconductor switch that produces 6-V picosecond electrical pulses. The pulses were produced on a microwave coplanar-strip transmission line lithographically patterned on the low-temperature (LT) GaAs. A 150-fs laser pulse was used to generate carriers in the LT GaAs gap between the metal strips, partially shorting a high DC voltage placed across the lines. The 6-V magnitude of the electrical pulses obtained is believed to be limited by the laser pulse power and not by the properties of the LT GaAs. Experiments were also performed on a picosecond photoconductor switch fabricated on a conventional ion-damaged silicon-on-sapphire substrate. Although comparable pulse durations were obtained, the highest pulse voltage achieved with the latter device was 0.6 V.

  1. Amplification of Picosecond Pulses in a 140-GHz Gyrotron-Traveling Wave Tube

    PubMed Central

    Kim, H. J.; Nanni, E. A.; Shapiro, M. A.; Sirigiri, J. R.; Woskov, P. P.; Temkin, R. J.

    2011-01-01

    An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro-TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE06 mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing by the finite gain bandwidth of 1.2 GHz. Experimental results taken over a wide range of parameters show good agreement with a theoretical model in the small signal gain regime. These results show that in order to limit the pulse broadening effect in gyrotron amplifiers, it is crucial to both choose an operating frequency at least several percent above the cutoff of the waveguide circuit and operate at the center of the gain spectrum with sufficient gain bandwidth. PMID:21230783

  2. Picosecond time-gated microscopy of UV-damaged plant tissue

    NASA Astrophysics Data System (ADS)

    Rehman, S.; Lukins, Philip B.

    2002-04-01

    We demonstrate that picosecond time-gated fluorescence microscopy can be used to monitor subtle changes in the kinetics and spatial distribution of perturbations to the molecular and cellular structure of plant tissue caused by ultraviolet radiation. Single-molecule experiments on Photosystem II and chloroplast preparations give picosecond fluorescence decay kinetics that are similar to those obtained previously on bulk samples. For green plant leaves, localized and well-defined cellular structure is seen for normal material whereas relatively diffuse and non-specific features are seen after UV-irradiation indicating significant UV-induced rupture of the cellular structure. The changes in the chlorophyll fluorescence decay kinetics indicate uncoupling of chlorophyll molecules in the light-harvesting system leading to inhibition of energy reorganization and transfer in the antennae and subsequent exciton transfer to the reaction centers.

  3. Tracing temperature in a nanometer size region in a picosecond time period

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-08-01

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model.

  4. Tracing temperature in a nanometer size region in a picosecond time period

    PubMed Central

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-01-01

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model. PMID:26293488

  5. A Quest for Measuring Ion Bunch Longitudinal Profiles with One Picosecond Accuracy in the SNS Linac.

    SciTech Connect

    Aleksandrov, Alexander V; Dickson, Richard W

    2012-01-01

    The SNS linac utilizes several accelerating structures operating at different frequencies and with different transverse focusing structures. Low-loss beam transport requires a careful matching at the transition points in both the transverse and longitudinal axes. Longitudinal beam parameters are measured using four Bunch Shape Monitors (used at many ion accelerator facilities, aka Feschenko devices). These devices, as initially delivered to the SNS, provided an estimated accuracy of about 5 picoseconds, which was sufficient for the initial beam commissioning. New challenges of improving beam transport for higher power operation will require measuring bunch profiles with 1-2 picoseconds accuracy. We have successfully implemented a number of improvements to maximize the performance characteristics of the delivered devices. We will discuss the current status of this instrument, its ultimate theoretical limit of accuracy, and how we measure its accuracy and resolution with real beam conditions.

  6. Tracing temperature in a nanometer size region in a picosecond time period.

    PubMed

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-01-01

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model. PMID:26293488

  7. Recording the synchrotron radiation by a picosecond streak camera for bunch diagnostics in cyclic accelerators

    NASA Astrophysics Data System (ADS)

    Vereshchagin, A. K.; Vorob'ev, N. S.; Gornostaev, P. B.; Dorokhov, V. L.; Kryukov, S. S.; Lozovoi, V. I.; Meshkov, O. I.; Nikiforov, D. A.; Smirnov, A. V.; Shashkov, E. V.; Schelev, M. Ya

    2016-02-01

    A PS-1/S1 picosecond streak camera with a linear sweep is used to measure temporal characteristics of synchrotron radiation pulses on a damping ring (DR) at the Budker Institute of Nuclear Physics (BINP) of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk). The data obtained allow a conclusion as to the formation processes of electron bunches and their 'quality' in the DR after injection from the linear accelerator. The expediency of employing the streak camera as a part of an optical diagnostic accelerator complex for adjusting the injection from a linear accelerator is shown. Discussed is the issue of designing a new-generation dissector with a time resolution up to a few picoseconds, which would allow implementation of a continuous bunch monitoring in the DR during mutual work with the electron-positron colliders at the BINP.

  8. Picosecond fiber MOPA pumped supercontinuum source with 39 W output power.

    PubMed

    Chen, Kang Kang; Alam, Shaif-Ul; Price, Jonathan H V; Hayes, John R; Lin, Dejiao; Malinowski, Andrew; Codemard, Christophe; Ghosh, Debashri; Pal, Mrinmay; Bhadra, Shyamal K; Richardson, David J

    2010-03-15

    We report a picosecond fiber MOPA pumped supercontinuum source with 39 W output, spanning at least 0.4-2.25 microm at a repetition rate of 114.8 MHz. The 2m long PCF had a large, 4.4 microm diameter core and a high-delta design which led to an 80% coupling efficiency, high damage threshold and rapid generation of visible continuum generation from the picosecond input pulses. The high and relatively uniform power density across the visible spectral region was approximately 31.7 mW/nm corresponding to peak power density of approximately 12.5 W/nm for the 21 ps input pulses. The peak power density was increased to 26.9 W/nm by reducing the repetition rate to 28 MHz. This represents an increase in both average and peak power compared to previously reported visible supercontinuum sources from either CW pumped or pulsed-systems. PMID:20389559

  9. Multiplex picosecond coherent Stokes raman spectroscopy of pentacene doped in naphthalene

    NASA Astrophysics Data System (ADS)

    Chang, Ta-Chau; Liu, Tie-Yue; Wu, Hsing-Mei; Li, Hung-Wen

    1992-09-01

    We present a study of the multiplex picosecond CSRS experiments of the mixed crystals of pentacene doped in naphthalene. By this method we are able to measure vibrational decay times from different species simultaneously. The shorter decay time measured for the 1385 cm -1 mode of naphthalene while increasing the concentration of pentacene and tuning the pump frequency near the absorption transition may be interpreted by the model of impurity perturbed domains.

  10. Picosecond spectroscopy of charge-transfer processes. Photochemistry of anthracene-tetranitromethane EDA complexes

    NASA Astrophysics Data System (ADS)

    Masnovi, J. M.; Huffman, J. C.; Kochi, J. K.; Hilinski, E. F.; Rentzepis, P. M.

    1984-04-01

    The temporal sequence of events that follow 532 nm excitation of electron donor-acceptor, EDA, complexes of several substituted anthracenes with tetranitromethane is monitored by means of picosecond spectroscopy. Excitation of the charge-transfer band of these EDA complexes produces high yields of 1 : 1 adducts. Absorption spectra and kinetics of the transient species involved in these photochemical reactions provide the basis for elucidation of the reaction mechanism following charge-transfer excitation to the ion pairs.

  11. Magnetic vortex dynamics on a picosecond timescale in a hexagonal permalloy pattern

    SciTech Connect

    Shim, J.-H.; Kim, D.-H.; Mesler, B.; Moon, J.-H.; Lee, K.-J.; Anderson, E. H.; Fischer, P.

    2009-12-02

    We have observed a motion of magnetic vortex core in a hexagonal Permalloy pattern by means of Soft X-ray microscopy. Pump-probe stroboscopic observation on a picosecond timescale has been carried out after exciting a ground state vortex structure by an external field pulse of 1 ns duration. Vortex core is excited off from the center position of the hexagonal pattern but the analysis of the core trajectory reveals that the motion is nongyrotropic.

  12. Applications of infrared free electron lasers in picosecond and nonlinear spectroscopy

    NASA Astrophysics Data System (ADS)

    Fann, W. S.; Benson, S. V.; Madey, J. M. J.; Etemad, S.; Baker, G. L.; Rothberg, L.; Roberson, M.; Austin, R. H.

    1990-10-01

    In this paper we describe two different types of spectroscopic experiments that exploit the characteristics of the infrared FEL, Mark III, for studies of condensed matter: - the spectrum of χ(3)(-3ω; ω, ω, ω) in polyacetylene: an application of the free electron laser in nonlinear optical spectroscopy, and - a dynamical test of Davydov-like solitons in acetanilide using a picosecond free electron laser. These two studies highlight the unique contributions FELs can make to condensed-matter spectroscopy.

  13. Observation of self-focusing in optical fibers with picosecond pulses.

    PubMed

    Baldeck, P L; Raccah, F; Alfano, R R

    1987-08-01

    Self-focusing was observed at Raman frequencies, using picosecond pulses propagating in a large-core optical fiber of 100-microm diameter. For intense input pulses, a continuum of Stokes frequencies was generated in a small ring-waveguide structure. The ring diameter of 11 microm was about 10 times smaller than the beam diameter at low intensities. The ring structure was attributed to an induced-gradient-index profile arising from the nonlinear index of refraction. PMID:19741807

  14. Shaping pulses using frequency conversion with a modulated picosecond free electron laser

    SciTech Connect

    Hooper, B.A.; Madey, J.M.J.

    1995-12-31

    Computer simulations and experiments indicate that we can shape the infrared picosecond pulses of the Mark III FEL in amplitude, frequency, and phase. Strongly modulated fundamental and second harmonic pulses have been generated by operating the Mark III FEL in the regime of strong sideband growth. In this paper, we present the results of simulations and experiments for second harmonic generation with fundamental inputs from 2 to 3 {mu}m.

  15. Observation of coherent undulator radiation from sub-picosecond electron pulses

    SciTech Connect

    Bocek, D.; Hernandez, M.; Kung, P.; Lihn, Hung-chi; Settakorn, C.; Wiedemann, H.

    1995-09-01

    The generation and observation of high power, coherent, far-infrared undulator radiation from sub-picosecond electron bunches at the SUNSHINE facility is reported. Coherent undulator radiation tunable from 50 to 200 microns wavelength is demonstrated. Measurements of the energy (up to 1.7 mJ per 1 microsecs macropulse), frequency spectrum, and spatial distribution of the radiation are reported. Apparent exponential growth of the radiated energy as a function of undulator length is observed.

  16. ARTICLES: Characteristics of the amplification of picosecond ultraviolet pulses in an XeCl amplifier

    NASA Astrophysics Data System (ADS)

    Platonenko, Viktor T.; Taranukhin, Vladimir D.

    1987-01-01

    A numerical investigation was made of the amplification of picosecond pulses in an XeCl amplifier, taking into account the real vibrational-rotational structure of the gain spectrum of the XeCl molecule. It was found that the coherent effects can be manifested and, in particular, that a marked reduction can take place in the duration of the pulses which are amplified.

  17. Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy

    SciTech Connect

    Gawelda, W.; Pham, V. T.; El Nahhas, A.; Kaiser, M.; Zaushitsyn, Y.; Bressler, C.; Chergui, M.; Johnson, S. L.; Grolimund, D.; Abela, R.; Hauser, A.

    2007-02-02

    We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy)3 at room temperature.

  18. Picosecond-time-resolved studies of nonradiative relaxation in ruby and alexandrite

    SciTech Connect

    Gayen, S.K.; Wang, W.B.; Petricevic, V.; Alfano, R.R.

    1985-01-01

    Dynamics of the nonradiative transitions between the /sup 4/T/sub 2/ pump band and the /sup 2/E storage level of the Cr/sup 3 +/ ion in ruby and alexandrite crystals is studied using the picosecond excite-and-probe absorption technique. A 527-nm picosecond pulse excites the /sup 4/T/sub 2/ state of the Cr/sup 3 +/ ion, and an infrared picosecond probe pulse monitors the subsequent growth and decay of population in the excited states as a function of pump-probe delay. An upper limit of 7 ps is determined for the nonradiative lifetime of the /sup 4/T/sub 2/ state in ruby. A vibrational relaxation time of 25 ps for the /sup 4/T/sub 2/ band in alexandrite is estimated. The time to attain thermal equilibrium population between the /sup 2/E and /sup 4/T/sub 2/ levels of alexandrite following excitation of /sup 4/T/sub 2/ band is estimated to be approx. 100 ps.

  19. Applications of picosecond lasers and pulse-bursts in precision manufacturing

    NASA Astrophysics Data System (ADS)

    Knappe, Ralf

    2012-03-01

    Just as CW and quasi-CW lasers have revolutionized the materials processing world, picosecond lasers are poised to change the world of micromachining, where lasers outperform mechanical tools due to their flexibility, reliability, reproducibility, ease of programming, and lack of mechanical force or contamination to the part. Picosecond lasers are established as powerful tools for micromachining. Industrial processes like micro drilling, surface structuring and thin film ablation benefit from a process, which provides highest precision and minimal thermal impact for all materials. Applications such as microelectronics, semiconductor, and photovoltaic industries use picosecond lasers for maximum quality, flexibility, and cost efficiency. The range of parts, manufactured with ps lasers spans from microscopic diamond tools over large printing cylinders with square feet of structured surface. Cutting glass for display and PV is a large application, as well. With a smart distribution of energy into groups of ps-pulses at ns-scale separation (known as burst mode) ablation rates can be increased by one order of magnitude or more for some materials, also providing a better surface quality under certain conditions. The paper reports on the latest results of the laser technology, scaling of ablation rates, and various applications in ps-laser micromachining.

  20. [Focusing properties of picosecond electric pulses in non-invasive cancer treatment].

    PubMed

    Long, Zaiquan; Yao, Chenguo; Li, Chengxiang; Mi, Yan; Sun, Caixin

    2010-10-01

    In the light of optical theory, we advanc an ultra-wideband impulse radiating antenna (IRA) which is composed of an ellipsoidal reflector and a cone radiator. The high-intensity ultra-short electric pulses radiated by IRA can be transferred into the deep target in tissue non-invasively and be focused effectively. With the focused picosecond electric pulses, the organelles (mitochondria) transmembrane potential shall change to collapse under which the tumor cells will be targetly induced to apoptosis, so the method of non-invasive treatment of tumors would be achieved. Based on the time-domain electromagnetic field theory, the propagation characteristics of picosecond electric pulses were analyzed with and without the context of biological tissue, respectively. The results show that the impulse characteristics of input pulse were maintained and the picosecond electric pulses can keep high resolution in target areas. Meanwhile, because of the dispersive nature of medium, the pulse amplitude of the pulses will attenuate and the pulse width will be broadened. PMID:21089684

  1. Few-femtosecond timing jitter from a picosecond all-polarization-maintaining Yb-fiber laser.

    PubMed

    Chen, Wei; Song, Youjian; Jung, Kwangyun; Hu, Minglie; Wang, Chingyue; Kim, Jungwon

    2016-01-25

    We characterize the timing jitter of a picosecond all-polarization-maintaining (all-PM) Yb-fiber laser using the optical cross-correlation method. For the 10 MHz all-normal dispersion mode-locked laser with ~0.5 nm spectral bandwidth, the measured high-frequency jitter is as low as 5.9 fs (RMS) when integrated from 10 kHz to the Nyquist frequency of 5 MHz. A complete numerical model with ASE noise is built to simulate the timing jitter characteristics in consideration of intracavity pulse evolution. The mutual comparison among simulation result, analytical model and experiment data indicate that the few femtosecond timing jitter from the picosecond fiber laser is attributed to the complete elimination of Gordon-Haus jitter by narrow bandpass filtering by a fiber Bragg grating (FBG). The low level of timing jitter from this compact and maintenance-free PM picosecond fiber laser source at a low MHz repetition rate is promising to advance a number of femtosecond-precision timing and synchronization applications. PMID:26832515

  2. Stretching of Picosecond Laser Pulses with Uniform Reflecting Volume Bragg Gratings

    NASA Astrophysics Data System (ADS)

    Mokhov, Sergiy

    It is shown that a uniform reflecting volume Bragg grating (VBG) can be used as a compact monolithic stretcher of high-power picosecond laser pulses in cases when chirped Bragg gratings with an appropriate chirp rate are difficult to fabricate. A chirp-free reflected stretched pulse is generated of almost rectangular shape when incident short pulse propagates along a grating and experiences local Bragg diffraction. The increase in duration of the reflected pulse is approximately equal to twice the propagation times along the grating. We derived the analytic expression for diffraction efficiency, which incorporates incident pulse duration, grating thickness, and amplitude of refractive index modulation, enabling an optimum selection of the grating for pulse stretching. The typical expected theoretical value of diffraction efficiency is about 10% after taking into account the spectral narrowing of the reflected emission. We believe that the relatively low energy efficiency of the proposed method is more than offset by a number of advantages, which are chirp-free spectrum of a stretched pulse, compactness, robustness, preservation of setup alignment and beam quality, and tolerance to high power. Obtained pulses of several tens of picoseconds can be amplified by standard methods which are not requiring special measures to avoid undesirable non-linear effects. We propose a simple and reliable method to control the temporal parameters of the high-power picosecond pulses using the same laser source and the VGB of variable thickness that can significantly simplify the experiments requiring different pulse durations.

  3. Toward picosecond time-resolved X-ray absorption studies of interfacial photochemistry

    NASA Astrophysics Data System (ADS)

    Gessner, Oliver; Mahl, Johannes; Neppl, Stefan

    2016-05-01

    We report on the progress toward developing a novel picosecond time-resolved transient X-ray absorption spectroscopy (TRXAS) capability for time-domain studies of interfacial photochemistry. The technique is based on the combination of a high repetition rate picosecond laser system with a time-resolved X-ray fluorescent yield setup that may be used for the study of radiation sensitive materials and X-ray spectroscopy compatible photoelectrochemical (PEC) cells. The mobile system is currently deployed at the Advanced Light Source (ALS) and may be used in all operating modes (two-bunch and multi-bunch) of the synchrotron. The use of a time-stamping technique enables the simultaneous recording of TRXAS spectra with delays between the exciting laser pulses and the probing X-ray pulses spanning picosecond to nanosecond temporal scales. First results are discussed that demonstrate the viability of the method to study photoinduced dynamics in transition metal-oxide semiconductor (SC) samples under high vacuum conditions and at SC-liquid electrolyte interfaces during photoelectrochemical water splitting. Opportunities and challenges are outlined to capture crucial short-lived intermediates of photochemical processes with the technique. This work was supported by the Department of Energy Office of Science Early Career Research Program.

  4. Detection of nonlinear picosecond acoustic pulses by time-resolved Brillouin scattering

    SciTech Connect

    Gusev, Vitalyi E.

    2014-08-14

    In time-resolved Brillouin scattering (also called picosecond ultrasonic interferometry), the time evolution of the spatial Fourier component of an optically excited acoustic strain distribution is monitored. The wave number is determined by the momentum conservation in photon-phonon interaction. For linear acoustic waves propagating in a homogeneous medium, the detected time-domain signal of the optical probe transient reflectivity shows a sinusoidal oscillation at a constant frequency known as the Brillouin frequency. This oscillation is a result of heterodyning the constant reflection from the sample surface with the Brillouin-scattered field. Here, we present an analytical theory for the nonlinear reshaping of a propagating, finite amplitude picosecond acoustic pulse, which results in a time-dependence of the observed frequency. In particular, we examine the conditions under which this information can be used to study the time-evolution of the weak-shock front speed. Depending on the initial strain pulse parameters and the time interval of its nonlinear transformation, our theory predicts the detected frequency to either be monotonically decreasing or oscillating in time. We support these theoretical predictions by comparison with available experimental data. In general, we find that picosecond ultrasonic interferometry of nonlinear acoustic pulses provides access to the nonlinear acoustic properties of a medium spanning most of the GHz frequency range.

  5. A low timing jitter picosecond microchip laser pumped by pulsed LD

    NASA Astrophysics Data System (ADS)

    Wang, Sha; Wang, Yan-biao; Feng, Guoying; Zhou, Shou-huan

    2016-07-01

    SESAM passively Q-switched microchip laser is a very promising instrument to replace mode locked lasers to obtain picosecond pulses. The biggest drawback of a passively Q-switched microchip laser is its un-avoided large timing jitter, especially when the pump intensity is low, i.e. at low laser repetition rate range. In order to obtain a low timing jitter passively Q-switched picosecond microchip laser in the whole laser repetition rate range, a 1000 kHz pulsed narrow bandwidth Fiber Bragg Grating (FBG) stablized laser diode was used as the pump source. By tuning the pump intensity, we could control the output laser frequency. In this way, we achieved a very low timing jitter passively Q-switched picosecond laser at 2.13 mW, 111.1 kHz. The relative timing jitter was only 0.0315%, which was around 100 times smaller compared with a cw LD pumped microchip working at hundred kilohertz repetition rate frequency range.

  6. High energy picosecond laser for applications in microstructuring of crystalline silicon

    NASA Astrophysics Data System (ADS)

    Lin, Xuechun; Yu, Haijuan; Huang, Yongguang; Zhang, Ling; Zhu, Hongliang

    2012-10-01

    Black silicon is very promising for the third generation Solar Cells, because of its fascinating light absorption of above 98% in visible spectrum and more than 90% in 800-2500 nm, and its surface micro-nano structures enlarge light trapping intermediate impurities levels caused by supersaturated doping expand absorptive limitation of crystalline Si. In recent years femtosecond laser pulses were widely used in the process of improving the absorptance by irradiating silicon surfaces with in the presence of different gases. Nevertheless, picosecond laser used to fabricate large-area black silicon is seldom reported. A diode-pumped picosecond Nd:YAG regenerative amplifier laser system designed for microstructuring the crystalline silicon was reported in this paper. At the repetition of 1 kHz, the system generated 1 W average-power, 26-ps-long pulses with a pulse energy of 1 mJ at 1064 nm, which corresponds the peak power of 38.5 MW. A 0.5 W second-harmonic 532 nm laser is achieved with a 20 mm long noncritically phase-matched lithium triborate (LBO) crystal from the 1W 1064 nm laser. igh optical absorption black Si irradiated with 1064 nm and 532 nm picosecond pulses in SF6 at different laser fluence. And the relationship between the surface morphology and the wavelength or the laser fluence was researched.

  7. Emergency Contraception

    MedlinePlus

    f AQ FREQUENTLY ASKED QUESTIONS FAQ114 CONTRACEPTION Emergency Contraception • What is emergency contraception (EC)? • How does EC work? • What are the different types of EC? • What is the most ...

  8. Emergency contraception

    MedlinePlus

    Morning-after pill; Postcoital contraception; Birth control - emergency; Plan B ... Emergency contraception most likely prevents pregnancy in the same way as regular birth control pills: By preventing or delaying ...

  9. Radiation Emergencies

    MedlinePlus

    ... day from sources such as sunlight. A radiation emergency would involve larger amounts of radiation and could ... are no guarantees of safety during a radiation emergency, you can take actions to protect yourself. You ...

  10. Heat emergencies

    MedlinePlus

    Heat emergencies or illnesses are caused by exposure to extreme heat and sun. Heat illnesses can be prevented by ... to regulate the temperature, and make a heat emergency more likely: Drinking alcohol before or during exposure ...

  11. Emergent Expertise?

    ERIC Educational Resources Information Center

    McGivern, Patrick

    2014-01-01

    The concept of emergence appears in various places within the literature on expertise and expert practice. Here, I examine some of these applications of emergence in the light of two prominent accounts of emergence from the philosophy of science and philosophy of mind. I evaluate these accounts with respect to several specific contexts in which…

  12. Childhood Emergencies

    MedlinePlus

    ... Fitness Tracker Save Your Life in the ER? Abdominal Pain Resources Home Safety Checklist ACEP Coloring Book Download the Coloring Book » Emergency Care For You American College of Emergency Phycisians Copyright © American College of Emergency Physicians 2016 Privacy Policy Terms of Use

  13. Design of a 50 TW/20 J chirped-Pulse Amplification Laser for High-Energy-Density Plasma Physics Experiments at the Nevada Terawatt Facility of the University of Nevada

    SciTech Connect

    Erlandson, A C; Astanovitskiy, A; Batie, S; Bauer, B; Bayramian, A; Caird, J A; Cowan, T; Ebbers, C; Fuchs, J; Faretto, H; Glassman, J; Ivanov, V; LeGalloudec, B; LeGalloudec, N; Letzring, S; Payne, S; Stuart, B

    2003-09-07

    We have developed a conceptual design for a 50 TW/20 J short-pulse laser for performing high-energy-density plasma physics experiments at the Nevada Terawatt Facility of the University of Nevada, Reno. The purpose of the laser is to develop proton and x-ray radiography techniques, to use these techniques to study z-pinch plasmas, and to study deposition of intense laser energy into both magnetized and unmagnetized plasmas. Our design uses a commercial diode-pumped Nd:glass oscillator to generate 3-nJ. 200-fs mode-locked pulses at 1059 m. An all-reflective grating stretcher increases pulse duration to 1.1 ns. A two-stage chirped-pulse optical parametric amplifier (OPCPA) using BBO crystals boosts pulse energy to 12 mJ. A chain using mixed silicate-phosphate Nd:glass increases pulse energy to 85 J while narrowing bandwidth to 7.4 nm (FWHM). About 50 J is split off to the laser target chamber to generate plasma while the remaining energy is directed to a roof-mirror pulse compressor, where two 21 cm x 42 cm gold gratings recompress pulses to {approx}350 fs. A 30-cm-focal-length off-axis parabolic reflector (OAP) focuses {approx}20 J onto target, producing an irradiance of 10{sup 19} W/cm{sup 2} in a 10-{micro}m-diameter spot. This paper describes planned plasma experiments, system performance requirements, the laser design, and the target area design.

  14. Picosecond spectroscopy of vibrational and electronic dynamics in high-pressure molecular solids

    SciTech Connect

    Crowell, R.A. II.

    1992-01-01

    Picosecond time resolved studies of vibrational and electronic dynamics in molecular solids are presented. Several uranyl compounds were selected that had large gaps in their vibrational energy density of states. Picosecond coherent anti-Stokes Raman measurements (psCARS) reveal that at 10 K vibrational relaxation occurs by at least a fifth order anharmonic mechanism. At elevated temperatures vibrational decay proceeds predominantly by a cubic anharmonic upconversion mechanism. The results of psCARS on a low temperature molecular solid in a high pressure diamond anvil cell are presented. For carbon disulfide pressure induced shifts in the phonon frequencies result in the opening up of a new relaxation pathway for the 2[nu][sub 2] mode. This pressure induced relaxation mechanism appears to dominate the dynamics of this mode at pressures greater than 19 kbar. Pressure dependent low temperature psCARS measurements for the [nu][sub 9], [nu][sub 8], and [nu][sub 5] of naphthalene are presented. Pressure induced density of states effects are isolated, allowing direct observations of pressure induced anharmonic coupling effects. The magnitude of the pressure induced anharmonic coupling is highly mode specific. psCARS measurements at low temperature are performed on homogeneous high pressure crystals and on highly strained crystals. Results are analyzed in terms of competition between vibrational relaxation and inhomogeneous dephasing. Changes in vibrational dephasing induced by a large negative pressure change ([minus][Delta]P [ge] 5 kbar) are used to determine the magnitude of inhomogeneous dephasing effects. The strain induced inhomogeneous dephasing is mode specific. Picosecond photon echo measurements on a molecular solid in a high pressure diamond anvil cell at low temperature are presented. Results for the O[sub 1] and O[sub 3] photosites in pentacene doped pterphenyl are presented and discussed in terms of pressure induced changes in the Debye frequency.

  15. Photoconductivity in organic thin films: From picoseconds to seconds after excitation

    NASA Astrophysics Data System (ADS)

    Day, J.; Subramanian, S.; Anthony, J. E.; Lu, Z.; Twieg, R. J.; Ostroverkhova, O.

    2008-06-01

    We present a detailed study, on time scales from picoseconds to seconds, of transient and continuous wave (cw) photoconductivity in solution-grown thin films of functionalized pentacene (Pc), anthradithiophene (ADT), and dicyanomethylenedihydrofuran (DCDHF). In all films, at temperatures of 285-350 K, we observe fast carrier photogeneration and nonthermally activated charge transport on picosecond time scales. At ˜30 ps after photoexcitation at room temperature and at applied electric field of 1.2×104 V/cm, values obtained for the product of mobility and photogeneration efficiency, μη, in ADT-tri-isoproplysilylethynyl-(TIPS)-F, Pc-TIPS, and DCDHF films are ˜0.018-0.025, ˜0.01-0.022, and ˜0.002-0.004 cm2/V s, respectively, depending on the film quality, and are weakly electric field dependent. In functionalized ADT and Pc films, the power-law decay dynamics of the transient photoconductivity is observed, on time scales of up to ˜1 μs after photoexcitation, in the best samples. In contrast, in DCDHF amorphous glass, most of the photogenerated carriers are trapped within ˜200 ps. Transport of photoexcited carriers on longer time scales is probed by cw illumination through an optical chopper, with a variable chopper frequency. In contrast with what is observed on picosecond time scales, charge carriers on millisecond and longer time scales are predominantly localized, and are characterized by a broad distribution of carrier lifetimes. Such carriers make the principal contributions to dc photoconductivity.

  16. Picosecond dynamics of photochemical systems. Final report, 1/1/79-6/30/80. [(Ketone) fluorenone; 1,4-diazobicyclooctane (amine)

    SciTech Connect

    Peters, K.S.

    1980-11-17

    The mechanism of the photoreduction of aromatic ketones by amines has been investigated using picosecond absorption spectroscopy. The experiments reveal that the process involves complete electron transfer occurring within a half-life of 20 picoseconds for benzophenone/Dabco and fluorenone/Dabco.

  17. Picosecond and nanosecond pulse delivery through a hollow-core Negative Curvature Fiber for micro-machining applications.

    PubMed

    Jaworski, Piotr; Yu, Fei; Maier, Robert R J; Wadsworth, William J; Knight, Jonathan C; Shephard, Jonathan D; Hand, Duncan P

    2013-09-23

    We present high average power picosecond and nanosecond pulse delivery at 1030 nm and 1064 nm wavelengths respectively through a novel hollow-core Negative Curvature Fiber (NCF) for high-precision micro-machining applications. Picosecond pulses with an average power above 36 W and energies of 92 µJ, corresponding to a peak power density of 1.5 TWcm⁻² have been transmitted through the fiber without introducing any damage to the input and output fiber end-faces. High-energy nanosecond pulses (>1 mJ), which are ideal for micro-machining have been successfully delivered through the NCF with a coupling efficiency of 92%. Picosecond and nanosecond pulse delivery have been demonstrated in fiber-based laser micro-machining of fused silica, aluminum and titanium. PMID:24104161

  18. 130-W picosecond green laser based on a frequency-doubled hybrid cryogenic Yb:YAG amplifier.

    PubMed

    Hong, Kyung-Han; Lai, Chien-Jen; Siddiqui, Aleem; Kärtner, Franz X

    2009-09-14

    130-W average-power picosecond green laser pulses at 514.5 nm are generated from a frequency-doubled hybrid cryogenic Yb:YAG laser. A second-harmonic conversion efficiency of 54% is achieved with a 15-mm-long noncritically phase-matched lithium triborate (LBO) crystal from a 240-W 8-ps 78-MHz pulse train at 1029 nm. The high-average-power hybrid laser system consists of a picosecond fiber chirped-pulse amplification seed source and a cryogenically-cooled double-pass Yb:YAG amplifier. The M(2) value of 2.7, measured at 77 W of second-harmonic power, demonstrates a good focusing quality. A thermal analysis shows that the longitudinal temperature gradient can be the main limiting factor in the second-harmonic efficiency. To our best knowledge, this is the highest-average-power green laser source generating picosecond pulses. PMID:19770908

  19. Picosecond pumping of extreme-ultraviolet lasers using preformed laser plasmas

    NASA Astrophysics Data System (ADS)

    Yamakoshi, H.; Herman, P. R.; Le Flohic, M. P.; Xiao, B.; Zhao, L.; Kulcsar, G.; Budnik, F. W.; Marjoribanks, R. S.

    1996-02-01

    Weak laser prepulses were used for the first time with picosecond-duration laser light to enhance laser-target absorption for efficient excitation of extreme-ultraviolet lasers. A traveling-wave excitation geometry and a self-healing mercury-wetted target were used with 300-ps prepulses to pump the photoionization Xe III laser at 109-nm wavelength. Fully saturated laser gain was demonstrated for both 32-ps and 1.4-ps small-signal gain coefficients exceeded 2 cm -1 for on-target laser fluences of only 4 J / cm2.

  20. Pulsed picosecond KGW:Nd3+ laser based on the Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Grabovski, Vitaly V.; Prokhorenko, Valentin I.; Yatskiv, Dmytro Y.

    1995-04-01

    Energetic, statistical, and temporal characteristics of a pico-second KGW:Nd laser based on the Sagnac interferometer are studied. All experiments are provided in comparison with the traditional linear cavity. The effect of stimulated Raman scattering suppression in such a specific cavity was found. Stimulated Raman scattering in KGW dumped all output parameters in the laser with a linear cavity. A new cavity scheme can solve such problems and provide for good output handling. It is shown that output pulse duration is larger in the proposed scheme compared with a linear cavity but other characteristics are much better.

  1. Picosecond laser ultrasonics for imaging of transparent polycrystalline materials compressed to megabar pressures.

    PubMed

    Kuriakose, Maju; Raetz, Samuel; Chigarev, Nikolay; Nikitin, Sergey M; Bulou, Alain; Gasteau, Damien; Tournat, Vincent; Castagnede, Bernard; Zerr, Andreas; Gusev, Vitalyi E

    2016-07-01

    Picosecond laser ultrasonics is an all-optical experimental technique based on ultrafast high repetition rate lasers applied for the generation and detection of nanometric in length coherent acoustic pulses. In optically transparent materials these pulses can be detected not only on their arrival at the sample surfaces but also all along their propagation path inside the sample providing opportunity for imaging of the sample material spatial inhomogeneities traversed by the acoustic pulse. Application of this imaging technique to polycrystalline elastically anisotropic transparent materials subject to high pressures in a diamond anvil cell reveals their significant texturing/structuring at the spatial scales exceeding dimensions of the individual crystallites. PMID:27026585

  2. 1016nm all fiber picosecond MOPA laser with 50W output.

    PubMed

    Qi, Xue; Chen, Sheng-Ping; Sun, Hai-Yue; Yang, Bing-Ke; Hou, Jing

    2016-07-25

    This paper presents an all fiber high power picosecond laser at 1016 nm in master oscillator power amplifier (MOPA) configuration. A direct amplification of this seed source encounters obvious gain competition with amplified spontaneous emission (ASE) at ~1030 nm, leading to a seriously reduced amplification efficiency. To suppress the ASE and improve the amplification efficiency, we experimentally investigate the influence of the gain fiber length and the residual ASE on the perforemance of the 1016 nm amplifier. The optimized 1016 nm MOPA laser exhibits an average power of 50 W and an optical conversion efficiency of 53%. PMID:27464139

  3. Si nanostructures grown by picosecond high repetition rate pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Pervolaraki, M.; Komninou, Ph.; Kioseoglou, J.; Athanasopoulos, G. I.; Giapintzakis, J.

    2013-08-01

    One-step growth of n-doped Si nanostructures by picosecond ultra fast pulsed laser deposition at 1064 nm is reported for the first time. The structure and morphology of the Si nanostructures were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Transmission electron microscopy studies revealed that the shape of the Si nanostructures depends on the ambient argon pressure. Fibrous networks, cauliflower formations and Si rectangular crystals grew when argon pressure of 300 Pa, 30 Pa and vacuum (10-3 Pa) conditions were used, respectively. In addition, the electrical resistance of the vacuum made material was investigated.

  4. Size Dependent Ultrafast Cooling of Water Droplets in Microemulsions by Picosecond Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Seifert, G.; Patzlaff, T.; Graener, H.

    2002-04-01

    The ultrafast thermal relaxation of reversed micelles in n-octane/AOT/water (where AOT denotes sodium di-2-ethylhexyl sulfosuccinate) microemulsions was investigated by time-resolved infrared pump-probe spectroscopy. This picosecond cooling process can be described in terms of heat diffusion, demonstrating a new method to determine the nanometer radii of the water droplets. The reverse micelles are stable against transient temperatures far above the equilibrium stability range. The amphiphilic interface layer (AOT) seems to provide an efficient heat contact between the water and the nonpolar solvent.

  5. Ultra-flat supercontinuum generation in cascaded photonic crystal fiber with picosecond fiber laser pumping

    NASA Astrophysics Data System (ADS)

    Zhang, Huanian; Li, Ping

    2016-08-01

    In this letter, a new method for achieving ultra-flat supercontinuum generation is proposed. A picosecond fiber laser was used as the pump source, in a cascaded photonic crystal fiber, ultra-flat supercontinuum generation spectrum at 3 dB level from 1070 up to 1630 nm is obtained, to our knowledge, the 3 dB bandwidth of 560 nm is the most flat supercontinuum generation obtained in photonic crystal fibers, the results indicated that our method is efficient for achieving ultra-flat supercontinuum, which will promote the technical applications of supercontinuum.

  6. Octave-spanning infrared supercontinuum generation in robust chalcogenide nanotapers using picosecond pulses.

    PubMed

    Shabahang, Soroush; Marquez, Michael P; Tao, Guangming; Piracha, Mohammad U; Nguyen, Dat; Delfyett, Peter J; Abouraddy, Ayman F

    2012-11-15

    We report on infrared supercontinuum generation extending over more than one octave of bandwidth, from 850 nm to 2.35 μm, produced in a single spatial mode from a robust, compact, composite chalcogenide glass nanotaper. A picosecond laser at 1.55 μm pumps a high-index-contrast, all-solid nanotaper that strongly confines the field to a 480 nm diameter core, while a thermally compatible built-in polymer jacket lends the nanotaper mechanical stability. PMID:23164864

  7. High-energy picosecond hybrid fiber/crystal laser for thin films solar cells micromachining

    NASA Astrophysics Data System (ADS)

    Lecourt, Jean-Bernard; Boivinet, Simon; Bertrand, Anthony; Lekime, Didier; Hernandez, Yves

    2015-05-01

    We report on an hybrid fiber/crystal ultra-short pulsed laser delivering high pulse energy and high peak power in the picosecond regime. The laser is composed of a mode-lock fiber oscillator, a pulse picker and subsequent fiber amplifiers. The last stage of the laser is a single pass Nd:YVO4 solid-state amplifier. We believe that this combination of both technologies is a very promising approach for making efficient, compact and low cost lasers compatible with industrial requirements.

  8. Spatiospectral and picosecond spatiotemporal properties of a broad area operating channeled-substrate-planar laser array

    NASA Technical Reports Server (NTRS)

    Yu, NU; Defreez, Richard K.; Bossert, David J.; Wilson, Geoffrey A.; Elliott, Richard A.

    1991-01-01

    Spatiospectral and spatiotemporal properties of an eight-element channeled-substrate-planar laser array are investigated in both CW and pulsed operating conditions. The closely spaced CSP array with strong optical coupling between array elements is characterized by a broad area laserlike operation determined by its spatial mode spectra. The spatiotemporal evolution of the near and far field exhibits complex dynamic behavior in the picosecond to nanosecond domain. Operating parameters for the laser device have been experimentally determined. These results provide important information for the evaluation of the dynamic behavior of coherent semiconductor laser arrays.

  9. Optical harmonic generation from animal tissues by the use of picosecond and femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Guo, Yici; Ho, P. P.; Tirksliunas, A.; Liu, Feng; Alfano, R. R.

    1996-12-01

    Second- and third-harmonic generations of femtosecond and picosecond laser pulses have been measured from chicken skin, muscle, and fat tissues. The magnitude of the harmonic signals showed a strong structural dependence with the signal from skin interface being the strongest. The polarization dependence of the signal was also measured and found to be consistent with the fact that the tissue samples were highly scattering random media. The second-harmonic- and third-harmonic-generation conversion efficiencies were found to be in the range of approximately 10 -7 to approximately 10-10.

  10. Dynamical test of Davydov-type solitons in acetanilide using a picosecond free-electron laser

    NASA Astrophysics Data System (ADS)

    Fann, Wunshain; Rothberg, Lewis; Roberson, Mark; Benson, Steve; Madey, John; Etemad, Shahab; Austin, Robert

    1990-01-01

    Picosecond infrared excitation experiments on acetanilide, an α-helix protein analog, indicate that the anomalous 1650-cm-1 band which appears on cooling of acetanilide crystals persists for at least several microseconds following rapid pulsed heating. The ground-state recovery time is 15+/-5 psec, consistent with a conventional mode strongly coupled to the phonon bath. We therefore suggest that the unusual temperature-dependent spectroscopy of acetanilide can be accounted for by slightly nondegenerate hydrogen atom configurations in the crystal.

  11. Note: Picosecond impulse generator driven by cascaded step recovery diode pulse shaping circuit.

    PubMed

    Choi, Gil Wong; Choi, Jin Joo; Han, Seung Hoon

    2011-01-01

    In this paper, a picosecond impulse generator using step recovery diodes (SRDs) is presented. In order to reduce the pulse width of an impulse generator, we employed a cascaded SRD pulse-shaping circuit. A short impulse generation is confirmed in numerical simulation of a time-transient circuit simulator. Measurements show that the measured pulse width of the cascaded SRD impulse generator is 250 ps at 10% of the peak amplitude, which is improved by 85 ps compared with a conventional SRD impulse generator. PMID:21280869

  12. Note: Picosecond impulse generator driven by cascaded step recovery diode pulse shaping circuit

    NASA Astrophysics Data System (ADS)

    Wong Choi, Gil; Joo Choi, Jin; Hoon Han, Seung

    2011-01-01

    In this paper, a picosecond impulse generator using step recovery diodes (SRDs) is presented. In order to reduce the pulse width of an impulse generator, we employed a cascaded SRD pulse-shaping circuit. A short impulse generation is confirmed in numerical simulation of a time-transient circuit simulator. Measurements show that the measured pulse width of the cascaded SRD impulse generator is 250 ps at 10% of the peak amplitude, which is improved by 85 ps compared with a conventional SRD impulse generator.

  13. Picosecond laser induced fragmentation of coarse Cu2O particles into nanoparticles in liquid media

    NASA Astrophysics Data System (ADS)

    Ali, Mokhtar; Remalli, Nagarjuna; Yehya, Fahem; Chaudhary, Anil Kumar; Srikanth, Vadali V. S. S.

    2015-12-01

    Micron sized cuprous oxide (Cu2O) particles are easily fragmented into nanosized (5-10 nm) particles using picosecond (ps) laser (wavelength = 532 nm) pulses. The coarse Cu2O particles are first synthesized by reducing copper chloride with the aid of honey. These particles are then dispersed in liquid media (double distilled water or ethanol) and exposed to ps laser pulses to obtain well-dispersed nanosized Cu2O particles. By using this method of fragmentation, morphology of the particles can be altered while retaining their crystal structure. The innate nature of this method allows continuous production of nanoparticles from coarser particles.

  14. Picosecond kinetics and Sn <-- S1 absorption spectra of retinoids and carotenoids

    NASA Astrophysics Data System (ADS)

    Bondarev, Stanislav L.; Tikhomirov, S. A.; Bachilo, Sergei M.

    1991-05-01

    Light energy absorption, as well as the subsequent photochemical and photophysical processes of cis -+trans isomerisation (vision and bacteriorhodopsin photosynthesis) and energy transfer (photosynthesis in green plants and micro organisms) take place in a pigment-protein complex including polyene chromophors, retinoids and carotenoids. Picosecond and subpicosecond studies of the spectral and kinetic characteristics of these processes are carried out in both complex photoreceptor and photosynthetic ms'2 and model systems with the use of solutions of retinoids and carotenoids.36 The lifetimes of the lower singlet-exited states S (21A; ) ofsome carotenoids in toluene at room temperature have been measured by the method of picosecond photolysis and amount to 8.6+/- 0.5 for all-trans-fl -carotene1 and 5.2 0.6 PS for canthaxanthin.5 /3 -carotene fluorescence at room temperature is practically absent, its yield being less than iO (Ref. 7). /1 -carotene fluorescence at 77 and 4.2 K in isopentane discovered by us8 is characterized by yields of (4+/-2) .iO and (8+/-3) . i0- and lifetimes of(4+/-2) .iO' and (8+/-3) .iO' and is due to the transitions from the higher S(1' B) state. The picosecond transient S -S absorption of/I - carotene in different solvents at 293 K is characterized by spectra in the 550-600 nm range.8 For retinoids, there is one work (Ref. 4) which gives the S, +-Si absorption spectrum of the Schiff base (aldimine) of retinal with amaz 465 mn in n-hexane at 290 K. The duration of transient absorption was 21 5 ps, although the fluorescence kinetics measured in this work (Ref. 4) at 298 K were characterized by two-component decay with r1 = 22 and r2 = 265 ps. The transient picosecond absorption spectra for retinal are absent in the literature and the lifetimes of its singlet-excited state at room temperature, measured by absorption and fluorescence, amount to 20+/-10 Ps in n-hexane3 and 17 Ps in ethanol,'9 respectively.

  15. Laser-induced damage threshold of silicon in millisecond, nanosecond, and picosecond regimes

    SciTech Connect

    Wang, X.; Shen, Z. H.; Lu, J.; Ni, X. W.

    2010-08-15

    Millisecond, nanosecond, and picosecond laser pulse induced damage thresholds on single-crystal are investigated in this study. The thresholds of laser-induced damage on silicon are calculated theoretically for three pulse widths based on the thermal damage model. An axisymmetric mathematical model is established for the transient temperature field of the silicon. Experiments are performed to test the damage thresholds of silicon at various pulse widths. The results indicate that the damage thresholds obviously increase with the increasing of laser pulse width. Additionally, the experimental results agree well with theoretical calculations and numerical simulation results.

  16. Picosecond Laser Studies of Third-Order Nonlinear Optical Properties in Organic Polymers

    NASA Astrophysics Data System (ADS)

    Cao, Xiaofan

    This dissertation makes the following theoretical and experimental contributions to the understanding of organic nonlinear optical materials in general, and of the nonlinear optical properties of polyquinoxaline (PQL) ladder polymers and metal-phthalocyanines doped in polycarbonate thin films in particular. (1) We developed a new model of the third-order nonlinear polarization density which has both "fast" (compared to 10psec, such as from electronic or lattice excitations) nonlinearity and "slow" (acoustic and thermal) components. This model enables a more accurate analysis than was possible previously of the different nonlinear optical processes seen in the picosecond laser studies of nonlinear optical properties of organic materials than was possible previously. (2) We interpreted our own picosecond four wave mixing measurements in ten polymers (in the PQL family) in terms of the new model parameters. (3) We have performed picosecond four-wave mixing measurement at 1064, (580-640), and 532 nm in Cr-phthalocyanine doped polycarbonate thin films. Our study supports the excitonic picture proposed by Ho et al.^{104 } (4) We observed for the first time a two -photon absorption state in Cr-Phthalocyanine near 0.5 eV. The two photon absorption coefficients which we determined by three independent methods agree well. (5) We showed that measuring the decay of ultrasonic waves induced by picosecond pulses is a superior way to measure acoustic velocity, acoustic damping, acousto-optic coupling constants, and thermal conductivity of materials. With this we studied the anomalous frequency dependence of sound damping in glasses and polymers. We propose a model for the diffusion of lattice "voids" in amorphous materials that accounts for some aspects of the anomalous ultrasonic sound damping. (6) We measured third harmonic generation in several PQL polymers and in a Cr-phthalocyanine doped polymer. Differences in four-wave mixing measurement were compared for five metal

  17. Simulating Picosecond X-ray Diffraction from shocked crystals by Post-processing Molecular Dynamics Calculations

    SciTech Connect

    Kimminau, G; Nagler, B; Higginbotham, A; Murphy, W; Park, N; Hawreliak, J; Kadau, K; Germann, T C; Bringa, E M; Kalantar, D; Lorenzana, H; Remington, B; Wark, J

    2008-06-19

    Calculations of the x-ray diffraction patterns from shocked crystals derived from the results of Non-Equilibrium-Molecular-Dynamics (NEMD) simulations are presented. The atomic coordinates predicted by the NEMD simulations combined with atomic form factors are used to generate a discrete distribution of electron density. A Fast-Fourier-Transform (FFT) of this distribution provides an image of the crystal in reciprocal space, which can be further processed to produce quantitative simulated data for direct comparison with experiments that employ picosecond x-ray diffraction from laser-irradiated crystalline targets.

  18. Simulating picosecond X-ray diffraction from crystals using FFT methods on MD output

    SciTech Connect

    Kimminau, Giles; Nagler, Bob; Higginbotham, Andrew; Murphy, William; Wark, Justin; Park, Nigel; Hawreliak, James; Kalantar, Dan; Lorenzana, Hector; Remington, Bruce

    2007-12-12

    Multi-million atom non-equilibrium molecular dynamics (MD) simulations give significant insight into the transient processes that occur under shock compression. Picosecond X-ray diffraction enables the probing of materials on a timescale fast enough to test such effects. In order to simulate diffraction patterns, Fourier methods are required to gain a picture of reciprocal lattice space. We present here results of fast Fourier transforms of atomic coordinates of shocked crystals simulated by MD, and comment on the computing power required as a function of problem size. The relationship between reciprocal space and particular experimental geometries is discussed.

  19. Picosecond Laser Machining of Metallic and Polymer Substrates for Fluidic Driven Self-Alignment

    NASA Astrophysics Data System (ADS)

    Römer, G. R. B. E.; Cerro, D. Arnaldo Del; Pohl, R.; Chang, B.; Liimatainen, V.; Zhou, Q.; Veld, A. J. Huis In `t.

    Fluidic self-alignment of micro-components relies on creating a receptor site that is able to confine a liquid droplet. When a micro-component is brought in contact with the droplet, capillary forces move the component to its final position. A method to stop the advancing of a liquid from a receptor site, consists of creating geometrical features, such as edges around the site. A picosecond pulsed laser source was used to create suitable edges in a metallic and a polyimide substrate. Subsequently, the self-alignment capabilities of these sites were tested. The receptor sites in polyimide showed the highest success rate.

  20. Generation of picosecond pulses with a gain-switched GaAs surface-emitting laser

    SciTech Connect

    Karin, J.R.; Melcer, L.G.; Nagarajan, R.; Bowers, J.E.; Corzine, S.W.; Morton, P.A.; Geels, R.S.; Coldren, L.A. )

    1990-09-03

    Pulses shorter than 4 ps (deconvolved) have been obtained by optically gain switching a GaAs multiple quantum well vertical-cavity surface-emitting laser with a picosecond dye laser. Pulse width and relative peak delay were measured as a function of pump power. A theoretical model of the large signal response agrees well with the measured data. The model predicts the minimum achievable pulse width and pulse delay for this device structure. Experimental results and calculated values indicate that very high modulation rates are possible with vertical-cavity surface-emitting lasers.

  1. Picosecond laser-driven terahertz radiation from large scale preplasmas of solid targets

    NASA Astrophysics Data System (ADS)

    Liao, G. Q.; Li, Y. T.; Li, C.; Su, L. N.; Zheng, Y.; Liu, M.; Dunn, J.; Nilsen, J.; Hunter, J.; Wang, W. M.; Sheng, Z. M.; Zhang, J.

    2016-05-01

    The terahertz (THz) radiation from the front of solid targets with a large-scale preplasma irradiated by relativistic picosecond laser pulses has been studied. The THz radiation measured at the specular direction nonlinearly increases with laser energy and an optimal plasma density scalelength is observed. Particle-in-cell simulations indicate that the radiation can be attributed to the model of mode conversion. While the THz radiation near the target normal direction is saturated with laser energy and plasma scalelength. Unlike the radiation in the specular direction’ the transient current formed at the plasma-vacuum interface could be responsible for the radiation near the target normal.

  2. A New Technology for Applanation Free Corneal Trephination: The Picosecond Infrared Laser (PIRL)

    PubMed Central

    Linke, Stephan J.; Frings, Andreas; Ren, Ling; Gomolka, Amadeus; Schumacher, Udo; Reimer, Rudolph; Hansen, Nils-Owe; Jowett, Nathan; Richard, Gisbert; Miller, R. J. Dwayne

    2015-01-01

    The impact of using a Femtosecond laser on final functional results of penetrating keratoplasty is low. The corneal incisions presented here result from laser ablations with ultrafast desorption by impulsive vibrational excitation (DIVE). The results of the current study are based on the first proof-of-principle experiments using a mobile, newly introduced picosecond infrared laser system, and indicate that wavelengths in the mid-infrared range centered at 3 μm are efficient for obtaining applanation-free deep cuts on porcine corneas. PMID:25781907

  3. Design and characterization of low loss 50 picoseconds delay line on SOI platform.

    PubMed

    Xiao, Zhe; Luo, Xianshu; Liow, Tsung-Yang; Lim, Peng Huei; Prabhathan, Patinharekandy; Zhang, Jing; Luan, Feng

    2013-09-01

    We design and experimentally demonstrate 50 picoseconds (ps) low loss delay line on 300 nm SOI platform. The delay line unit consists of straight rib waveguide and strip bend section linked by a transition taper waveguide. Low propagation loss of ~0.1 dB/cm is achieved on the straight rib waveguide. With taking into account both low loss and desirable delay, a complete design and characterization process for passive delay line is presented. Our measurement results show that about 0.7 dB excess loss is achievable for 50 ps delay. The loss can be further reduced by adjusting the layout parameters. PMID:24104002

  4. Effective pulse recompression after nonlinear spectral broadening in picosecond Yb-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Zaytsev, A. K.; Wang, C.-L.; Lin, C.-H.; You, Y.-J.; Tsai, F.-H.; Pan, C.-L.

    2012-02-01

    We report the performance of a picosecond master-oscillator power amplifier (MOPA) system based on a diode-pumped solid-state (DPSS) seed laser and Yb-doped fiber amplifier. An average power of 28 W at ˜200 MHz repetition rate is achieved by using only one amplification stage. We found that positive nonlinear phase shift induced by nonlinear effect in the active fiber can be effectively compensated by a grating pair. A pulse duration of ˜1.6 ps is shown after recompression.

  5. High-visibility two-photon interference at a telecom wavelength using picosecond-regime separated sources

    SciTech Connect

    Aboussouan, Pierre; Alibart, Olivier; Ostrowsky, Daniel B.; Baldi, Pascal; Tanzilli, Sebastien

    2010-02-15

    We report on a two-photon interference experiment in a quantum relay configuration using two picosecond regime periodically poled lithium niobate (PPLN) waveguide based sources emitting paired photons at 1550 nm. The results show that the picosecond regime associated with a guided-wave scheme should have important repercussions for quantum relay implementations in real conditions, essential for improving both the working distance and the efficiency of quantum cryptography and networking systems. In contrast to already reported regimes, namely, femtosecond and CW, it allows achieving a 99% net visibility two-photon interference while maintaining a high effective photon pair rate using only standard telecom components and detectors.

  6. Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector

    SciTech Connect

    Smith, Richard J.; Light, Roger A.; Johnston, Nicholas S.; Pitter, Mark C.; Somekh, Mike G.; Sharples, Steve D.

    2010-02-15

    This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

  7. Graded Al sub x Ga sub 1-x as photoconductive devices for high efficiency picosecond optoelectronic switching

    SciTech Connect

    Morse, J.D.; Mariella, R.P. ); Dutton, R.W. . Center for Integrated Systems)

    1990-10-01

    Picosecond photoconductivity has been achieved for a variety of semiconductor materials by techniques which have now become almost standard. Enhanced scattering by the excessive amount of deep level defects which provide for picosecond recombination lifetimes significantly reduce the mobility, degrading the responsivity of the photoconductor. This paper will present a concept where improved responsivity is achievable by utilizing a graded bandgap Al{sub x}Ga{sub 1-x}As active detecting layer grown on a high defect density GaAs layer by molecular beam epitaxy (MBE). 7 refs., 6 figs.

  8. Contextual Emergence

    NASA Astrophysics Data System (ADS)

    Atmanspacher, Harald

    The concept of contextual emergence has been proposed as a nonreductive, yet well-defined relation between different levels of description of physical and other systems. It yields a formally sound and empirically applicable procedure to translate between descriptive levels in an overall consistent fashion. This will be discussed for the contextual emergence of mental states from a neural level of description.

  9. Picosecond time-resolved fluorescence spectroscopy of K-590 in the bacteriorhodopsin photocycle.

    PubMed Central

    Atkinson, G H; Blanchard, D; Lemaire, H; Brack, T L; Hayashi, H

    1989-01-01

    The fluorescence spectrum of a distinct isometric and conformational intermediate formed on the 10(-11) s time scale during the bacteriorhodopsin (BR) photocycle is observed at room temperature using a two laser, pump-probe technique with picosecond time resolution. The BR photocycle is initiated by pulsed (8 ps) excitation at 565 nm, whereas the fluorescence is generated by 4-ps laser pulses at 590 nm. The unstructured fluorescence extends from 650 to 880 nm and appears in the same general spectral region as the fluorescence spectrum assigned to BR-570. The transient fluorescence spectrum can be distinguished from that assigned to BR-570 by a larger emission quantum yield (approximately twice that of BR-570) and by a maximum intensity near 731 nm (shifted 17 nm to higher energy from the maximum of the BR-570 fluorescence spectrum). The fluorescence spectrum of BR-570 only is measured with low energy, picosecond pulsed excitation at 590 nm and is in good agreement with recent data in the literature. The assignment of the transient fluorescence spectrum to the K-590 intermediate is based on its appearance at time delays longer than 40 ps. The K-590 fluorescence spectrum remains unchanged over the entire 40-100-ps interval. The relevance of these fluorescence data with respect to the molecular mechanism used to model the primary processes in the BR photocycle also is discussed. PMID:2713439

  10. Picosecond pulsed infrared laser tuned to amide I band dissociates polyglutamine fibrils in cells.

    PubMed

    Kawasaki, Takayasu; Ohori, Gaku; Chiba, Tomoyuki; Tsukiyama, Koichi; Nakamura, Kazuhiro

    2016-09-01

    Amyloid fibrils are causal substances for serious neurodegenerative disorders and amyloidosis. Among them, polyglutamine fibrils seen in multiple polyglutamine diseases are toxic to neurons. Although much efforts have been made to explore the treatments of polyglutamine diseases, there are no effective drugs to block progression of the diseases. We recently found that a free electron laser (FEL), which has an oscillation wavelength at the amide I band (C = O stretch vibration mode) and picosecond pulse width, was effective for conversion of the fibril forms of insulin, lysozyme, and calcitonin peptide into their monomer forms. However, it is not known if that is also the case in polyglutamine fibrils in cells. We found in this study that the fibril-specific β-sheet conformation of polyglutamine peptide was converted into nonfibril form, as evidenced by the infrared microscopy and scanning-electron microscopy after the irradiation tuned to 6.08 μm. Furthermore, irradiation at this wavelength also changed polyglutamine fibrils to their nonfibril state in cultured cells, as shown by infrared mapping image of protein secondary structure. Notably, infrared thermography analysis showed that temperature increase of the cells during the irradiation was within 1 K, excluding thermal damage of cells. These results indicate that the picosecond pulsed infrared laser can safely reduce amyloid fibril structure to the nonfibril form even in cells. PMID:27342599