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Sample records for all-pm femtosecond yb-doped

  1. Mode-locked femtosecond all-normal all-PM Yb-doped fiber laser at 1060 nm

    Science.gov (United States)

    Bowen, Patrick; Singh, Harman; Runge, Antoine; Provo, Richard; Broderick, Neil G. R.

    2016-04-01

    We report an all-normal-dispersion, all-fibre, all-PM, laser operating at a central wavelength of 1060 nm. The laser is mode-locked using a nonlinear amplifying loop mirror and generates linearly polarised pulses that can be compressed to 360 fs. The laser is based on our earlier scheme operating at 1030 nm [1] and we discuss the similarities and differences between the two configurations. We also present amplification up to an output power of 1 W using a commercially built amplifier and show through numerical methods that this pulse may be recompressible to 1.65 ps.

  2. Femtosecond pulse generation and amplification in Yb-doped fibre oscillator–amplifier system

    Indian Academy of Sciences (India)

    P K Mukhopadhyay

    2010-11-01

    In recent times ytterbium (Yb) doped fibre-based mode-locked master oscillator and power amplifier have attracted a great deal of interest because of their inherent advantages like flexibility, reliability, compactness, high power handling capability and diffraction limited output beam quality as compared to the solid-state counterpart. But, to successfully develope of high-power femtosecond oscillator–amplifier system based on Yb- doped fibre, an appropriate choice of the mode-locking regime and the amplifier geometry are required. Development of an all-fibre integrated high-power Yb-doped fibre oscillator–amplifier system in which the advantages of a fibre-based system can be fully exploited remained a challenge as it requires the careful optimization of dispersion, nonlinearity, gain and ASE contribution. In this article, femto-second pulse generation in Yb-doped fibre oscillator in different mode-locking regimes are reviewed and the details of development and characterization of an all-fibre, high-power, low-noise amplifier system seeded by an all-normal-dispersion mode-locked Yb-doped fibre laser oscillator is described. More than 10 W of average power is obtained from the fibre oscillator–amplifier system at a repetition rate of 43 MHz with diffraction-limited beam quality. Amplified pulses are de-chirped to sub-160 fs duration in a grating compressor. This is the first 10 W-level source of femtosecond pulses with completely fibre-integrated amplification comprised of commercially available components.

  3. Hybrid femtosecond fiber laser outcrossing Er-doped fiber and Yb-doped fiber

    Science.gov (United States)

    Kim, Yunseok; Park, Sanguk; Kim, Seung-Woo

    2014-07-01

    A hybridized scheme of a fiber femtosecond pulse laser was devised with the aim of grafting the frequency comb of an Er-doped fiber oscillator, stabilized around a 1.550 μm center wavelength, onto the 1.0 μm emission range of an Yb-doped fiber amplifier. Test results showed that the frequency comb is successfully transferred to a new 1.034 μm center wavelength with a spectral bandwidth of 21 nm, upholding an original frequency stability of 3.71 × 10-13 at 10 s averaging. This work demonstrates the feasibility of outcrossing different kinds of fibers to shift the spectral range of the frequency comb over a large operating span without loss of stability.

  4. Monolithic Highly Stable Yb-Doped Femtosecond Fiber Lasers for Applications in Practical Biophotonics

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2012-01-01

    Operational and environmental stability of ultrafast laser systems is critical for their applications in practical biophotonics. Mode-locked fiber lasers show great promise in applications such as supercontinuum sources or multiphoton microscopy systems. Recently, substantial progress has been made...... in the development of all-fiber nonlinear-optical laser control schemes, which resulted in the demonstration of highly stable monolithic, i.e., not containing any free-space elements, lasers with direct fiber-end delivery of femtosecond pulses. This paper provides an overview of the progress in the...... development of such all-fiber mode-locked lasers based on Yb-fiber as gain medium, operating at the wavelength around 1 $\\mu$m, and delivering femtosecond pulses reaching tens of nanojoules of energy....

  5. Monolithic stabilized Yb-fiber All-PM laser directly delivering nJ-level femtosecond pulses

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality.......We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality....

  6. Mode-locked Yb-doped fiber laser emitting broadband pulses at ultra-low repetition rates

    CERN Document Server

    Bowen, Patrick; Provo, Richard; Harvey, John D; Broderick, Neil G R

    2016-01-01

    We report on an environmentally stable, Yb-doped, all-normal dispersion, mode-locked fibre laser that is capable of creating broadband pulses with ultra-low repetition rates. Specifically, through careful positioning of fibre sections in an all-PM-fibre cavity mode-locked with a nonlinear amplifying loop mirror, we achieve stable pulse trains with repetition rates as low as 506 kHz. The pulses have several nanojules of energy and are compressible down to ultrashort (< 500 fs) durations.

  7. Laser and spectroscopic properties of Yb-doped apatite crystals

    International Nuclear Information System (INIS)

    Favorable spectroscopic and laser properties were measured in several Yb-doped apatite crystals: Ca5(PO4)3F, Sr5(PO4)3F, and Ca5-xSrx(PO4)3F (x=1-3). The properties included absorption and emission spectra, and laser pumping (slope efficiency)

  8. Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    . The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output......We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror...

  9. Tunable femtosecond Cherenkov fiber laser

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper;

    2014-01-01

    We demonstrate electrically-tunable femtosecond Cherenkov fiber laser output at the visible range. Using an all-fiber, self-starting femtosecond Yb-doped fiber laser as the pump source and nonlinear photonic crystal fiber link as the wave-conversion medium, ultrafast, milliwatt-level, tunable...... and spectral isolated Cherenkov radiation at visible wavelengths are reported. Such a femtosecond Cherenkov laser source is promising for practical biophotonics applications....

  10. Guided mode gain competition in Yb-doped rod-type photonic crystal fibers

    DEFF Research Database (Denmark)

    Poli, Federica; Passaro, Davide; Cucinotta, Annamaria;

    2009-01-01

    The gain competition among the guided modes in Yb-doped rod-type photonic crystal fibers with a low refractive index core is investigated with a spatial model to demonstrate the fiber effective single-mode behaviour.......The gain competition among the guided modes in Yb-doped rod-type photonic crystal fibers with a low refractive index core is investigated with a spatial model to demonstrate the fiber effective single-mode behaviour....

  11. Synthesis and characterization of (Ba,Yb doped ceria nanopowders

    Directory of Open Access Journals (Sweden)

    Branko Matović

    2011-06-01

    Full Text Available Nanometric size (Ba, Yb doped ceria powders with fluorite-type structure were obtained by applying selfpropagating room temperature methods. Tailored composition was: Ce0.95−xBa0.05YbxO2−δ with fixed amount of Ba − 0.05 and varying Yb content “x” from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice parameters have been studied. Röntgen diffraction analyses (XRD were used to characterize the samples at room temperature. Also, high temperature treatment (up to 1550°C was used to follow stability of solid solutions. The mean diameters of the nanocrystals are determined from the full width at half maxima (FWHM of the XRD peaks. It was found that average diameter of crystallites is less than 3 nm. WilliamsonHall plots were used to separate the effect of the size and strain in the nanocrystals.

  12. All-fiber femtosecond Cherenkov radiation source

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe;

    2012-01-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion med......An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave......-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics...

  13. Novel materials for Yb and Er-Yb doped microchip lasers

    OpenAIRE

    Hellström, Jonas

    2006-01-01

    The objective of this thesis has been to investigate novel host material configurations for high-power end-pumped Er-Yb co-doped, or Yb doped microchip lasers and try to increase their performance. In Er-Yb co-doped systems, the main limitation is the thermal shortcomings of the phosphate glass host material. The thesis presents some novel results that contribute to the search for a crystalline replacement. In Yb doped systems, most end-pumped schemes reported have been using relatively low-p...

  14. Mass fabrication of homogeneously Yb-doped silica nanoparticles and their spectroscopic properties

    International Nuclear Information System (INIS)

    A large number of homogeneously Yb-doped silica nanoparticles were continually fabricated in a vapor synthesis route, in which the Yb doping level can be well controlled by varying either the heating temperature or the carrier gas flow rate of the Yb precursor. The sizes, shapes, and morphologies of the nanoparticles were examined, and no crystallites and no Yb2O3 clusters were observed in the nanoparticles. These nanoparticles exhibit a clear Yb3+-derived absorption at around 973-975 nm and a dependence of the emission intensity and decay time on the doping level, much different from that of sintered pellets.

  15. Multi-Frequency Soliton Complex in Er/Yb-Doped Fiber Amplifier

    Science.gov (United States)

    Kang, Jin U.; Kim, Do-Hyun; Khurgin, Jacob B.; Akhmediev, Nail N.; Han, Haewook; Shaw, Harry; Day, John H. (Technical Monitor)

    2001-01-01

    We experimentally investigated presence of multi-frequency soliton complex that exist in high power Er/Yb-doped Fiber Amplifier. The complex with the spectral bandwidth in excess of 100 nm is bound by the Kerr nonlinearity and exhibit stable propagation.

  16. Thermal effects in Yb-doped double-cladding Distributed Modal Filtering rod-type fibers

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Jørgensen, Mette Marie; Laurila, Marko; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard; Leick, Lasse; Broeng, Jes; Cucinotta, Annamaria; Selleri, Stefano

    2012-01-01

    The effects of thermally-induced refractive index change in Yb-doped Distributed Modal Filtering (DMF) photonic crystal fibers are investigated, where high-order mode suppression is obtained by resonant coupling with high index elements in the cladding. The temperature distribution on the fiber...

  17. Tunable passively harmonic mode-locked Yb-doped fiber laser with Lyot-Sagnac filter.

    Science.gov (United States)

    Li, Ming; Zou, Xin; Wu, Jian; Shi, Jindan; Qiu, Jifang; Hong, Xiaobin

    2015-10-10

    A novel passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all normal dispersion is proposed and experimentally demonstrated based on a semiconductor saturable absorption mirror and tunable Lyot-Sagnac filter. By only tuning the bandwidth of the filter at fixed pump power, the repetition rate of 9.87 to 167.8 MHz (corresponding to 17th-order harmonic) is obtained. This is the highest repetition rate and harmonic order for a passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all-normal dispersion to the best of our knowledge. The signal-to-noise ratio and super-mode suppression ratio for all harmonic orders are higher than 65 and 35 dB, respectively, which shows the high stability of the fiber laser. PMID:26479821

  18. Properties of Yb-doped scintillators: YAG, YAP, LuAG

    Energy Technology Data Exchange (ETDEWEB)

    Belogurov, S. E-mail: belogurov@pd.infn.it; Bressi, G.; Carugno, G.; Grishkin, Yu

    2004-01-01

    A big number of Yb:YAG samples is analyzed. Emission and transmittance spectra are measured. Light output and decay time vs. temperature are measured for charge transfer (CT) and IR scintillation. Light yield (LY) of the best laser crystals is by a factor 2.4 higher than the value measured for the samples of typical scintillator quality. A pulse shape dependence on e-beam energy density is observed for the IR scintillation. A new efficient Yb doped scintillator is found-Yb:YAP. CT scintillation in a high Z material Yb:LuAG is confirmed. A new scintillation material, potentially interesting for neutrino physics, is proposed: Yb doped garnet or perovskite containing indium in the host lattice. Some prospective research directions are indicated.

  19. Properties of Yb-doped scintillators: YAG, YAP, LuAG

    International Nuclear Information System (INIS)

    A big number of Yb:YAG samples is analyzed. Emission and transmittance spectra are measured. Light output and decay time vs. temperature are measured for charge transfer (CT) and IR scintillation. Light yield (LY) of the best laser crystals is by a factor 2.4 higher than the value measured for the samples of typical scintillator quality. A pulse shape dependence on e-beam energy density is observed for the IR scintillation. A new efficient Yb doped scintillator is found-Yb:YAP. CT scintillation in a high Z material Yb:LuAG is confirmed. A new scintillation material, potentially interesting for neutrino physics, is proposed: Yb doped garnet or perovskite containing indium in the host lattice. Some prospective research directions are indicated

  20. Experimental observation of soliton molecule evolution in Yb-doped passively mode-locked fiber lasers

    International Nuclear Information System (INIS)

    We have observed soliton molecules with variable modulation depth of spectra in a passively mode-locked dispersion-managed Yb-doped fiber laser. The soliton molecule we experimentally investigated presents diatomic and tetratomic types. With the enhancement of pump power, the laser alternately operates at solitons molecule, temporal-separation-oscillation solitons, and harmonic mode-locked states. Moreover, the phase of solitons molecule is only locked at low pump, and excess pump would cause phase vibration. (letters)

  1. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    B N Upadhyaya

    2014-01-01

    High-power laser generation using Yb-doped double-clad fibres with conversion efficiencies in excess of 80% have attracted much attention during the last decade due to their inherent advantages in terms of very high efficiency, no misalignment due to in-built intracore fibre Bragg gratings, low thermal problems due to large surface to volume ratio, diffraction-limited beam quality, compactness, reliability and fibre-optic beam delivery. Yb-doped fibres can also provide a wide emission band from ∼1010 nm to ∼1170 nm, which makes it a versatile laser medium to realize continuous-wave (CW), Q-switched short pulse, and mode-locked ultrashort pulse generation for various applications. In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical mechanisms involved in its generation has been described. A study on the generation of high-power CWfibre laser of 165Woutput power and generation of high peak power nanosecond pulses from acousto-optic Q-switched fibre laser has also been presented.

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

    Science.gov (United States)

    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.

  3. Yb-doped phosphate double-cladding optical fiber laser for high-power applications

    OpenAIRE

    Mura, Emanuele; Lousteau, Joris; Boetti, Nadia Giovanna; Scarpignato, Gerardo Cristian; Milanese, Daniel

    2013-01-01

    A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The mai...

  4. All-fiber femtosecond Cherenkov radiation source.

    Science.gov (United States)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

    2012-07-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580-630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics such as bioimaging and microscopy. PMID:22743523

  5. All-fiber femtosecond Cherenkov radiation source

    OpenAIRE

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2012-01-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. ...

  6. High-energy, kHz, picosecond hybrid Yb-doped chirped-pulse amplifier.

    Science.gov (United States)

    Chang, Chun-Lin; Krogen, Peter; Hong, Kyung-Han; Zapata, Luis E; Moses, Jeffrey; Calendron, Anne-Laure; Liang, Houkun; Lai, Chien-Jen; Stein, Gregory J; Keathley, Phillip D; Laurent, Guillaume; Kärtner, Franz X

    2015-04-20

    We report on a diode-pumped, hybrid Yb-doped chirped-pulse amplification (CPA) laser system with a compact pulse stretcher and compressor, consisting of Yb-doped fiber preamplifiers, a room-temperature Yb:KYW regenerative amplifier (RGA), and cryogenic Yb:YAG multi-pass amplifiers. The RGA provides a relatively broad amplification bandwidth and thereby a long pulse duration to mitigate B-integral in the CPA chain. The ~1030-nm laser pulses are amplified up to 70 mJ at 1-kHz repetition rate, currently limited by available optics apertures, and then compressed to ~6 ps with high efficiency. The near-diffraction-limited beam focusing quality is demonstrated with M(x)(2) = 1.1 and M(y)(2) = 1.2. The shot-to-shot energy fluctuation is as low as ~1% (rms), and the long-term energy drift and beam pointing stability for over 8 hours measurement are ~3.5% and <6 μrad (rms), respectively. To the best of our knowledge, this hybrid laser system produces the most energetic picosecond pulses at kHz repetition rates among rod-type laser amplifiers. With an optically synchronized Ti:sapphire seed laser, it provides a versatile platform optimized for pumping optical parametric chirped-pulse amplification systems as well as driving inverse Compton scattered X-rays. PMID:25969056

  7. All-fiber normal-dispersion femtosecond laser

    OpenAIRE

    Kieu, K.; Wise, F. W.

    2008-01-01

    Spectral filtering of a chirped pulse can be a strong pulse-shaping mechanism in all-normal-dispersion femtosecond fiber lasers. We report an implementation of such a laser that employs only fiber-format components. The Yb-doped fiber laser includes a fiber filter, and a saturable absorber based on carbon nanotubes. The laser generates 1.5-ps, 3-nJ pulses that can be dechirped to 250 fs duration outside the cavity.

  8. Unidirectional dissipative soliton operation in an all-normal-dispersion Yb-doped fiber laser without an isolator.

    Science.gov (United States)

    Li, Daojing; Shen, Deyuan; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-09-10

    We demonstrate self-started unidirectional dissipative soliton operation and noise-like pulse operation in an all-normal-dispersion bidirectional Yb-doped fiber laser mode-locked by nonlinear polarization rotation. The laser works unidirectionally once mode-locking is achieved due to the cavity directional nonlinearity asymmetry along with the nonlinear polarization rotation mode-locking mechanism. PMID:26368963

  9. Unidirectional dissipative soliton operation in an-normal-dispersion bidirectional Yb-doped fiber laser without an isolator

    CERN Document Server

    Li, Daojing; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-01-01

    We demonstrate self-started unidirectional dissipative soliton operation and noise-like pulse operation in an all-normal-dispersion bidirectional Yb-doped fiber laser mode-locked by nonlinear polarization rotation. The laser works unidirectional once mode locking was achieved due to the cavity directional nonlinearity asymmetry along with the nonlinear polarization rotation mode locking mechanism.

  10. All-normal-dispersion multi-wavelength dissipative soliton Yb-doped fiber laser

    International Nuclear Information System (INIS)

    We propose and demonstrate an all-normal-dispersion multi-wavelength dissipative soliton Yb-doped fiber laser with a periodic birefringence fiber filter, for the first time to our best knowledge. Numerical simulations show that single-, dual-, and multi-wavelength dissipative solitons can be generated under appropriate filter bandwidth and saturation power. Under a certain filter bandwidth, the generated wavelength number of multi-wavelength mode-locked dissipative solitons is related to the saturation power, decreasing with increasing saturation power. The maximal and minimal attainable wavelength spacing of multi-wavelength dissipative solitons are also investigated, which are 21 nm and 4.6 nm, respectively, according to our simulations. Furthermore, the generation of multi-wavelength dissipative solitons has been verified by experiments. Dual- and three-wavelength dissipative solitons with a wavelength spacing of 16.4 nm have been achieved. (letter)

  11. Smoothing of the inversion profile in Nd- and Yb-doped solid-state laser elements

    International Nuclear Information System (INIS)

    A solid state selectivity pumped laser is considered now seriously as a candidate to the driver for the future power plant based on a ''pure'' fusion or a ''hybrid'' nuclear-thermonuclear reactor. In connection with an elaboration of selective pumping techniques for solid-state laser-drivers, a stored energy formation in solid state media under absorption of a narrow-band pumping radiation has been considered. The calculations demonstrate the possibility of the inversion profile smoothing in the slab-like Nd- and Yb-doped active elements pumped from excited levels of activator's or sensitizer's ions. A possibility of the Nd:glass and iodine lasers usage to carry out modelling experiments on selective pumping at the several kJ energy level is discussed

  12. Recent developments in polycrystalline oxide fiber laser materials: production of Yb-doped polycrystalline YAG fiber

    Science.gov (United States)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian; Parthasarathy, Triplicane; Cheng, Michael; Hopkins, Frank K.

    2011-09-01

    Laser quality, polycrystalline oxide fibers offer significant advantages over state-of-the-art silica fiber for high energy lasers. Advanced ceramic processing technology, along with a novel powder production process, has potential to produce oxide fibers with an outstanding optical quality for use in the fiber laser applications. The production of contaminant-free green fibers with a high packing density, as well as uniform packing distribution, is a key factor in obtaining laserquality fibers. High quality green fibers are dependent on the powder quality combined with the appropriate slurry formulation. These two fundamental technologies were successfully developed at UES, and used to produce Yb-doped yttrium aluminum garnet (YAG) fibers with high optical quality, high chemical purity, and suitable core diameters down to 20-30 microns.

  13. Sintering and optical quality of highly transparent yb-doped yttrium lanthanum oxide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Maxim; Zayats, Sergey [Institute of Electrophysics UrB of RAS, Amundsen st 106, 620016 Ekaterinburg (Russian Federation); Kopylov, Yury; Kravchenko, Valery [Institute of Radioengineering and Electronics named after V.A. Kotelnikov, RAS, Vvedensky Sq. 1, 141120 Fryazino, Moscow region (Russian Federation)

    2013-06-15

    To produce highly transparent Yb-doped yttrium lanthanum oxide (Yb{sup 3+}:(La{sub x}Y{sub 1-x}){sub 2}O{sub 3}) ceramics two original technologies were used: laser synthesis of nanopowder and pulsed magnetic compacting. Sintering of the compacts in vacuum 3 x 10{sup -4} Pa at 1600-1700 C during 13 hours led to transparent ceramics fabrication. The ceramics with relative density higher than 99.99% and grain size about 40 {mu}m were fabricated. Full transmittance of 1.8 mm thick Yb{sub 0,11}La{sub 0,23}Y{sub 1,66}O{sub 3} ceramics reaches 82.5% rate at 800 nm. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Q-Switched Large-Mode-Area Yb-Doped Fibre Laser Using GaAs as Saturable Absorber

    Institute of Scientific and Technical Information of China (English)

    FU Sheng-Gui; GUO Zhan-Cheng; SI Li-Bin; ZHAO Ying; YUAN Shu-Zhong; DONG Xiao-Yi

    2007-01-01

    A passive Q-switched large-mode-area Yb-doped fibre laser is demonstrated using a GaAs wafer as the saturable absorber. A high Yb doping concentration double-clad fibre with a core diameter of 30 μm and a numerical aperture of 0.07 is used to increase the laser gain volume, permitting greater energy storage and higher output power than conventional fibres. The maximum average output power is 7.2 W at 1080nm wavelength, with the shortest pulse duration of 580ns and the highest peak power of 161 W when the laser is pumped with a 25 W diode laser operating at 976 nm. The repetition rate increases with the pump power linearly and the highest repetition rate of 77kHz is obtained in the experiment.

  15. Long-period fiber grating as wavelength selective element in double-clad Yb-doped fiber-ring lasers

    CERN Document Server

    Peterka, P; Dussardier, Bernard; Slavik, R; Honzatko, P; Kubecek, V

    2009-01-01

    Selection of operating wavelength of the Yb-doped fiber-ring lasers using longperiod fiber gratings (LPFGs) is suggested. In the proposed method, customized LPFG that sustains high powers serves as a broad-band rejection filter. It modifies the net gain profile of the laser, enabling the peak gain to occur at a designed wavelength. Spectral range of oscillation between 1050-1110 nm was experimentally demonstrated. This range can be extended to both shorter and longer wavelengths with proper design of the LPFG and length of the Yb-doped fiber. The gratings were inscribed by CO2 laser and the grating period down to 175 ?m was achieved being, to our best knowledge, the shortest reported LPFG period using this technique.

  16. Effect of pump wavelength on self-induced laser line sweeping in Yb-doped fiber laser

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Petr; Peterka, Pavel; Kubeček, V.

    Vol. 8775. BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING, 2013 - (Kalli, K.; Kanka, J.; Mendez, A.) ISBN 978-0-8194-9577-8. ISSN 0277-786X. [Conference on Micro -structured and Specialty Optical Fibres II. Prague (CZ), 15.04.2013-17.04.2013] R&D Projects: GA MŠk(CZ) ME10119 Institutional support: RVO:67985882 Keywords : Laser line sweeping * fiber lasers * Yb-doped Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  17. Low-repetition-rate all-fiber all-normal-dispersion Yb-doped mode-locked fiber laser

    International Nuclear Information System (INIS)

    We demonstrate a low-repetition-rate all-fiber all-normal-dispersion Yb-doped mode-locked fiber laser. Stable mode-locking is achieved by nonlinear polarization rotation and its spectral-filtering effect. Nanosecond pulses with steep edges spectrum at repetition rate 217.4 kHz are achieved. Our preliminary experiment shows that it is a promising seed for all-fiber amplifier system

  18. Highly Efficient Self-Starting Femtosecond Cr:Forsterite Laser

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bin-Sin; ZHANG Yong-Dong; ZHONG Xin; WEI Zhi-Yi

    2008-01-01

    We report a highly efficient and high power self-starting femtosecond Cr:forsterite laser pumped by a 1064-nm Yb doped fibre laser. Five chirped mirrors are used to compensate for the intra-cavity group-delay dispersion,and the mode-locking is initiated by a semiconductor saturable absorber mirror (SESAM). Under pump power of 7.9 W, stable femtosecond laser pulses with average power of 760mW are obtained, yielding a pump power slope efficiency of 12.3%. The measured pulse duration and spectral bandwidth (FWHM) are 46 fs and 45 nm;the repetition rate is 82 MHz.

  19. Femtosecond micromachining of symmetric waveguides at 1.5 microm by astigmatic beam focusing.

    Science.gov (United States)

    Cerullo, G; Osellame, R; Taccheo, S; Marangoni, M; Polli, D; Ramponi, R; Laporta, P; De Silvestri, S

    2002-11-01

    We report on a new spatial beam-shaping approach for fabrication of waveguides with a circular transverse profile by femtosecond laser pulses, using an astigmatic beam and controlling both beam waist and focal position in the tangential and sagittal planes. We apply this technique to write single-mode active waveguides at 1.5microm in Er:Yb-doped glass substrates. The experimental results are well described by a simple nonlinear absorption model. PMID:18033408

  20. Structural characterization and EXAFS wavelet analysis of Yb doped ZnO by wet chemistry route

    International Nuclear Information System (INIS)

    Highlights: • Optical and electrical properties of ZnO are influenced by lanthanide doping. • Optical and electrical properties of ZnO are influenced by lanthanide positioning. • Yb is incorporated in the Oh sites of the wurtzite structure. • There is not Yb2O3 clustering or segregation for treatments below 800 °C. - Abstract: Lanthanide doped ZnO are interesting materials for optical and electrical applications. The wide band gap of this semiconductor makes it transparent in the visible range (Egap = 3.2 eV), allowing a sharp emission from intra shell transition from the lanthanides. From the electrical side, ZnO is a widely used material in varistors and its electrical properties can be tailored by the inclusion of lanthanides. Both applications are influenced by the location of the lanthanides, grain boundaries or lattice inclusion. Yb doped ZnO samples obtained by wet chemistry route were annealed at different temperatures and characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Rietveld refinement of XRD data, and X-ray Absorption Fine Structure (XAFS). These techniques allowed to follow the changes occurred in the matrix and the Yb environment. The use of the Cauchy continuous wavelet transform allowed identifying a second coordination shell composed of Zn atoms, supporting the observations from XRD Rietveld refinement and XAFS fittings. The information obtained confirmed the incorporation of Yb in Oh sites of the wurtzite structure without Yb2O3 clustering in the lattice

  1. 100-fs-level diode-pumped Yb-doped laser amplifiers

    Science.gov (United States)

    Delaigue, M.; Pouysegur, J.; Ricaud, S.; Hönninger, C.; Mottay, E.

    2013-03-01

    Ultrashort pulse lasers with pulse duration on the level of 100 fs can be used for à variety of interesting applications that rely on multiphoton processes or ultrafast dynamics. Up to now, this field was reserved to Ti:sapphire-based laser systems that exhibit a quite complex laser architecture and relatively low laser efficiency. This may be an important reason why such applications could not yet penetrate into large scale industrial applications. We have realized an Yb-doped tungstate-based regenerative amplifier in innovative amplifier architecture. We succeeded to produce 106-fs-pulses at 70μJ and 140 fs at 40 μJ pulse energy, respectively. The average power is on the level of several Watts. The optimized management and exploitation of dispersive and nonlinear effects during the amplification process inside the regenerative amplifier cavity enabled the generation of such short pulses with excellent temporal quality and in an extremely simple and robust laser architecture that is well suited for industrial environments. Applying the same amplifier architecture to an Yb:YAG thin disk regenerative amplifier enabled the generation of pulses as short as 360-fs at high pulse energies exceeding 200 μJ and high average powers of more than 30 W.

  2. Structural characterization and EXAFS wavelet analysis of Yb doped ZnO by wet chemistry route

    Energy Technology Data Exchange (ETDEWEB)

    Otal, Eugenio H., E-mail: eugenio.otal@citedef.gob.ar [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina); Sileo, Elsa [INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Aguirre, Myriam H. [Dept. of Physics Condensed Matter, University of Zaragoza (Spain); Laboratory of Advanced Microscopy (LMA), Institute of Nanoscience of Aragón (INA), University of Zaragoza (Spain); Fabregas, Ismael O. [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Kim, Manuela [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina)

    2015-02-15

    Highlights: • Optical and electrical properties of ZnO are influenced by lanthanide doping. • Optical and electrical properties of ZnO are influenced by lanthanide positioning. • Yb is incorporated in the O{sub h} sites of the wurtzite structure. • There is not Yb{sub 2}O{sub 3} clustering or segregation for treatments below 800 °C. - Abstract: Lanthanide doped ZnO are interesting materials for optical and electrical applications. The wide band gap of this semiconductor makes it transparent in the visible range (E{sub gap} = 3.2 eV), allowing a sharp emission from intra shell transition from the lanthanides. From the electrical side, ZnO is a widely used material in varistors and its electrical properties can be tailored by the inclusion of lanthanides. Both applications are influenced by the location of the lanthanides, grain boundaries or lattice inclusion. Yb doped ZnO samples obtained by wet chemistry route were annealed at different temperatures and characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Rietveld refinement of XRD data, and X-ray Absorption Fine Structure (XAFS). These techniques allowed to follow the changes occurred in the matrix and the Yb environment. The use of the Cauchy continuous wavelet transform allowed identifying a second coordination shell composed of Zn atoms, supporting the observations from XRD Rietveld refinement and XAFS fittings. The information obtained confirmed the incorporation of Yb in O{sub h} sites of the wurtzite structure without Yb{sub 2}O{sub 3} clustering in the lattice.

  3. Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

    DEFF Research Database (Denmark)

    Poli, F.; Lægsgaard, Jesper; Passaro, D.; Cucinotta, A.; Selleri, S.; Broeng, Jes

    2009-01-01

    higher-order mode (HOM), stressing the difference between their spatial distributions, with respect to the uniform refractive index core. In the present analysis a rod-type PCF with a 19-missing air-hole core, whose radius is 30 mum, has been considered. Initially, a PCF step-index model has been applied...... to identify a proper ring characteristic that is width, position and refractive index. Then rod-type PCF designs have been optimized with a full-vector modal solver based on the finite-element method. Then, the amplification properties of the Yb-doped rod-type PCFs have been investigated by assuming...

  4. Multiple Dissipative Solitons in a Long-Cavity Normal-Dispersion Mode-Locked Yb-Doped Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang-Zhen; XIAO Xiao-Sheng; MEI Jia-Wei; YANG Chang-Xi

    2012-01-01

    Transitional operations of multiple dissipative solitons in a long-cavity normal-dispersion Yb-doped fiber laser are experimentally investigated.Multiple dissipative solitons,including a stable soliton pair and a soliton triplet are observed by increasing the pump power or adjusting the polarization controllers.Two main boundaries of the stable asymmetric soliton and oscillating soliton are found between steady mode-locking.Moreover,multiple dissipative solitons with greater quantities of solitons are observed with pump power increasing.The experimental results agree well with a previous numerical study of multiple dissipative solitons.

  5. High-gain amplification in Yb:CaF2 crystals pumped by a high-brightness Yb-doped 976 nm fiber laser

    International Nuclear Information System (INIS)

    We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way towards very promising innovative lasers and amplifiers schemes merging the Yb-doped solid state and fiber technologies. (authors)

  6. Characterization of the lasing properties of a 5%Yb doped Lu.sub.2./sub.SiO.sub.5./sub. crystal along its three optical axes

    Czech Academy of Sciences Publication Activity Database

    Toci, G.; Pirri, A.; Beitlerová, Alena; Shoji, Y.; Yoshikawa, A.; Hybler, Jiří; Nikl, Martin; Vannini, M.

    2015-01-01

    Roč. 23, č. 10 (2015), s. 13210-13221. ISSN 1094-4087 Institutional support: RVO:68378271 Keywords : Lu 2 SiO 5 * Yb-doped * laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.488, year: 2014

  7. Optimization and control of the sweeping range in an Yb-doped self-sweeping fiber laser

    Science.gov (United States)

    Lobach, I. A.; Tkachenko, A. Yu; Kablukov, S. I.

    2016-04-01

    Influence of the laser cavity parameters (an active fiber length and output coupling losses) and the temperature of elements (active fiber and pump laser diode) on the sweeping range in an Yb-doped self-sweeping laser is investigated. The obtained results show that the sweeping spectral region is shifted to shorter wavelengths for shorter active fibers and with increasing absorbed power. This allows one to obtain self-sweeping operation in a broad range within a ytterbium gain bandwidth from 1028 to 1080 nm. At the same time, there are optimal cavity parameters at which the sweeping span is the broadest (>20 nm). Good agreement between the experimental sweeping range and the calculated maximum gain wavelength is demonstrated.

  8. Pulsed laser deposition and thermoelectric properties of In-and Yb-doped CoSb3 skutterudite thin films

    KAUST Repository

    Sarath Kumar, S. R.

    2011-07-29

    In-and Yb-doped CoSb3 thin films were prepared by pulsed laser deposition. Process optimization studies revealed that a very narrow process window exists for the growth of single-phase skutterudite films. The electrical conductivity and Seebeck coefficient measured in the temperature range 300-700 K revealed an irreversible change on the first heating cycle in argon ambient, which is attributed to the enhanced surface roughness of the films or trace secondary phases. A power factor of 0.68 W m-1 K-1 was obtained at ∼700 K, which is nearly six times lower than that of bulk samples. This difference is attributed to grain boundary scattering that causes a drop in film conductivity. Copyright © Materials Research Society 2011.

  9. Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

    International Nuclear Information System (INIS)

    In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution (NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs. The pump-induced carrier envelope offset frequency (f0) nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop (PLL) electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 mHz within an hour. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. High order harmonic mode-locking in an all-normal-dispersion Yb-doped fiber laser with a graphene oxide saturable absorber

    Science.gov (United States)

    Huang, S. S.; Wang, Y. G.; Yan, P. G.; Zhang, G. L.; Zhao, J. Q.; Li, H. Q.; Lin, R. Y.

    2014-01-01

    A high order passive harmonic mode-locking (HML) Yb-doped all-normal-dispersion fiber laser based on a graphene oxide saturable absorber has been experimentally demonstrated. For two different pump powers and different polarization states of the laser cavity, lower order and higher order HML have been achieved. The highest 30th-order harmonic (31.86 MHz) was achieved with subnanosecond pulse duration; this is transitional from a bunched multipulse state.

  11. High order harmonic mode-locking in an all-normal-dispersion Yb-doped fiber laser with a graphene oxide saturable absorber

    International Nuclear Information System (INIS)

    A high order passive harmonic mode-locking (HML) Yb-doped all-normal-dispersion fiber laser based on a graphene oxide saturable absorber has been experimentally demonstrated. For two different pump powers and different polarization states of the laser cavity, lower order and higher order HML have been achieved. The highest 30th-order harmonic (31.86 MHz) was achieved with subnanosecond pulse duration; this is transitional from a bunched multipulse state. (paper)

  12. Terahertz radiation using log-spiral-based low-temperature-grown InGaAs photoconductive antenna pumped by mode-locked Yb-doped fiber laser.

    Science.gov (United States)

    Kong, Moon Sik; Kim, Ji Su; Han, Sang Pil; Kim, Namje; Moon, Kiwon; Park, Kyung Hyun; Jeon, Min Yong

    2016-04-01

    We demonstrate a terahertz (THz) radiation using log-spiral-based low-temperature-grown (LTG) InGaAs photoconductive antenna (PCA) modules and a passively mode-locked 1030 nm Yb-doped fiber laser. The passively mode-locked Yb-doped fiber laser is easily implemented with nonlinear polarization rotation in the normal dispersion using a 10-nm spectral filter. The laser generates over 250 mW of the average output power with positively chirped 1.58 ps pulses, which are dechirped to 127 fs pulses using a pulse compressor outside the laser cavity. In order to obtain THz radiation, a home-made emitter and receiver constructed from log-spiral-based LTG InGaAs PCA modules were used to generate and detect THz signals, respectively. We successfully achieved absorption lines over 1.5 THz for water vapor in free space. Therefore, we confirm that a mode-locked Yb-doped fiber laser has the potential to be used as an optical source to generate THZ waves. PMID:27136997

  13. Ferromagnetic half-metallic characteristic and phase transition in rare-earth Yb doped SiC: A GGA+U study

    International Nuclear Information System (INIS)

    The electronic, magnetic and structural properties of rare earth Yb doped on SiC are investigated theoretically based on the density functional theory (DFT). Both zincblende (ZB) and rocksalt (RS) structures of SiC have been calculated. We found that Si3YbC4 with ZB exhibits a complete half-metallic characteristic with a wide gap more than 1.8 eV using GGA and GGA+U methods. However, the half-metallicity is destroyed with RS. The sensitivity of magnetic moments of Si3YbC4 as a function of pressure is also discussed, there are two magnetic phase transition points with increased pressure. The exchange interaction between local Yb-4f electrons and conduction electrons plays an important role in their heavy fermion characters. The exchange splitting of the conduction band is confirmed to be much larger than that of the valence band in Si3YbC4, which makes the holes-mediated ferromagnetism in this material. - Highlights: • Yb-doped SiC with zincblende are predicted half-metallic materials. • Two phase transition points, one is magnetic transition and the other is structure transition with increased pressure. • The calculated band gap using the GGA+U approach is larger than the GGA values. • The study of the exchange splitting shows that Yb-doped SiC makes the holes-mediated ferromagnetism

  14. All-PM fiber, net normal cavity, Tm-doped fiber laser

    Science.gov (United States)

    Aguergaray, Claude

    2016-03-01

    We demonstrate herein a PM-fiber based cavity design capable of supporting many different pulse dynamics, such as soliton propagation or dissipative solitons in a dispersion managed cavity. By changing the dispersion of the fiber Bragg grating of the cavity we modify the net cavity dispersion, and thus stimulate various pulse dynamics. In particular we demonstrate the first net normal cavity, all-PM, all-fiber, dipersion managed cavity operating the in the 2μm range. Furthermore, we also demonstrate an all-fiber all-PM MOPA system capable of delivering up to 6 W of average power at 16 MHz by direct amplification of 70 ps long narrowband pulses. The amplifier stages are not fully saturated and are currently limited by the pump power available.

  15. Lasing properties of new Yb-doped borate compounds with varying gadolinium and yttrium concentration

    Science.gov (United States)

    Manek-Hönninger, Inka; Chavoutier, Marie; Jubera, Véronique; Descamps, Dominique; Veber, Philippe; Velazquez, Matias; Garcia, A.; Canioni, L.

    2011-02-01

    We show spectroscopic and lasing properties of new ytterbium-doped borate compounds with the structure Li6(Gd(1- x)Yx)0.75Yb0.25(BO3)3 with x = 0, 0.25, 0.5, 0.75 and 1, respectively. All compounds show large emission spectra suitable for femtosecond pulse generation. We studied the laser performances in a diode-pumped linear laser cavity on about 1- mm-thick crystal samples having an ytterbium doping concentration of 22 %. The compounds show all cw lasing at wavelengths around 1040 to 1060 nm with a slope efficiency of 32 %. The maximum observed output power was 460 mW at an incident pump power of 1.6 W at 972 nm.

  16. Flexibly controllable multi-pulse mode-locked MOPA Yb-doped fiber laser in all normal dispersion regime

    Science.gov (United States)

    Bu, Chenxi; Wang, Chinhua

    2013-09-01

    A Controllable, high energy, all normal dispersion (ANDi), passively mode-locked Yb-doped fiber laser is demonstrated with a Master Oscillator Power-Amplifier (MOPA) structure. The mode-locking is achieved by nonlinear polarization evolution (NPE). different types of laser pulse are achieved from fundamental mode-locked (FML) single pulse to twin pulse and then to harmonically mode-locked (HML) pulses (the maximum order is 7 times) by adjusting quarter-wave plates (QWPS) and a half-wave plate (HWP) in our system. Using a cascaded long-period fiber grating as the spectral filter, the center wavelength of our laser is fixed at 1034nm.The repetition frequency rate of the FML pulse is 1.53MHz with a pulse width of 817ps. The maximum average energy is 450 mW and the maximum pulse energy of FML single pulse is 294 nJ. Besides, the 517nm green laser output is also achieved by using a LiB3O5 (LBO) crystal as the frequency doubling crystal. The maximum average of the green pulse is 4.71mW.

  17. A controllable noise-like operation regime in a Yb-doped dispersion-mapped fiber ring laser

    Science.gov (United States)

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

    2013-04-01

    We report the generation of tunable high-energy noise-like pulses with a super-broadband spectrum from a Yb-doped dispersion-mapped fiber ring laser. Self-starting noise-like operation can be maintained over a relatively large range of pumping powers (4-13 W). The corresponding output power varies from 0.1 to 1.45 W. The maximum 3 dB spectral bandwidth of the noise-like pulses is about 48.2 nm while the output energy is as high as 47 nJ, limited by optical damage of the components. The central wavelength of the noise-like pulses can be tuned easily over ˜12 nm. The bandwidth and duration of the generated wave packets can also be controlled. The use of a negative dispersion-delay line and spectral filter are found to be important for generating such high-power noise-like operation. Experimental results are in good agreement with theoretical simulations.

  18. Electrically tunable fiber-integrated Yb-doped laser covering 74 nm based on a fiber Bragg grating array

    Science.gov (United States)

    Tiess, T.; Rothhardt, M.; Chojetzki, C.; Jäger, M.; Bartelt, H.

    2015-03-01

    Fiber lasers provide the foundation to combine an excellent beam quality in single mode operation with a robust and highly efficient design. Based on fiber-integrated configurations, they are employed in many different applications ranging from industry over research to medical technology. However, there is lots of potential to approach even new fields of applications e.g. in spectroscopy based on tunable systems with an adjustable emission wavelength. We present a novel tuning concept for pulsed fiber-integrated laser systems using an array of fiber Bragg gratings (FBGs) as discrete spectral filter. Based on stacking many standard FBGs, the bandwidth and filter properties are easy to scale by increasing the number of gratings allowing huge tuning ranges as well as tailored tuning characteristics. In this work, we demonstrate the potential of this electrically controlled tuning concept. Using an Ytterbium (Yb)-doped fiber laser, we investigate the general tuning characteristics. With variable pulse durations in the nanosecond regime, we demonstrate high signal contrast (~45 dB), excellent wavelength stability and narrow linewidth (knowledge, is the largest bandwidth reported based on a monolithic filter design.

  19. Lattice dynamics and substrate-dependent transport properties of (In, Yb)-doped CoSb3 skutterudite thin films

    KAUST Repository

    Sarath Kumar, S. R.

    2011-10-24

    Lattice dynamics, low-temperature electrical transport, and high-temperature thermoelectric properties of (In, Yb)-doped CoSb3thin films on different substrates are reported. Pulsed laser deposition under optimized conditions yielded single-phase polycrystalline skutterudite films. Raman spectroscopy studies suggested that In and Yb dopants occupy the cage sites in the skutterudite lattice. Low-temperature electrical transport studies revealed the n-type semiconducting nature of the films with extrinsic and intrinsic conduction mechanisms, in sharp contrast to the degenerate nature reported for identical bulk samples. Calculations yielded a direct bandgap close to 50 meV with no evidence of an indirect gap. The carrier concentration of the films was identical to that reported for the bulk and increased with temperature beyond 250 K. The higher resistivity exhibited is attributed to the enhanced grain boundary scattering in films with a high concentration of grains. The maximum power factor of ∼0.68 W m−1 K−1 obtained at 660 K for the film on glass is found to be nearly four times smaller compared to that reported for the bulk. The observed difference in the power factors of the films on different substrates is explained on the basis of the diffusion of oxygen from the substrates and the formation of highly conducting CoSb2 phase upon the oxidation of CoSb3.

  20. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    International Nuclear Information System (INIS)

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  1. Switchable dual-pulse-shape mode-locked figure-eight all-PM fibre master oscillator with 0.5 W-level average output

    Science.gov (United States)

    Kobtsev, Sergey; Ivanenko, Aleksey; Fedotov, Yurii; Smirnov, Sergey V.; Golubtsov, Artur; Khripunov, Sergey

    2016-03-01

    For the first time a method for switching between generation of single- and double-scale pulses has been demonstrated in a mode-locked figure-eight NALM-based all-PM-fibre Yb master oscillator by adjustment of two pumps power. Introduction into a F8 configuration of a non-linear amplifying loop mirror with two active media not only ensured relatively high average output power of the master oscillator (> 0.5 W at 22-MHz repetition rate), but also allowed switching laser operation from one pulse type (single-scale with duration of <10 ps) to another - femtosecond clusters with envelope width of 16 ps and sub-pulse duration <200 fs.

  2. Luminescent properties of Yb-doped LaSc3(BO3)4 under VUV excitation

    International Nuclear Information System (INIS)

    Ytterbium doped borate crystals are promising laser media, e.g. in LaSc3(BO3)4 (LSB) matrices large distance between ytterbium ions results in reduced concentration quenching of the ytterbium f-f luminescence [Petermann, K., Fagundes-Peters, D., Johansen, O., Mond, M., Peters, V., Romero, J.J., Kutovoi, S., Speiser, J., Giesen, A., 2005. Highly Yb-doped oxides for thin-disc lasers. J. Crystal Growth 275, 135-140]. Yb3+ ions in complex oxides in addition to the 4f → 4f transitions often manifest fast charge transfer luminescence (CTL) in the UV-visible range. In some borates it was not observed at all, like in orthoborates of Sc, Y and La [Van Pieterson, L., Heeroma, M., de Heer, E., Meijerink, A., 2000. Charge transfer luminescence of Yb3+. J. Lumin. 91, 177-193]; in haloborates Sr2B5O9X, where X = Cl, Br, the UV/visible luminescence was attributed to ytterbium CTL though it looked substantially different from other matrices [Dotsenko, V.P., Berezovskaya, I.V., Pyrogenko, P.V., Efryushina, N.P., Rodniy, P.A., Eijk van, C.W.E., Sidorenko, A.V., 2002. Valence states and luminescence properties of ytterbium ions in strontium haloborates. J. Solid State Chem. 166, 271-276]; while in oxyborate Li2Lu5O4(BO3)3 'classical' CTL was observed [Jubera, V., Garcia, A., Chaminade, J.P., Guillen, F., Sablayrolles, Jean, Fouassier, C., 2007. Yb3+ and Yb3+-Eu3+ luminescent properties of the Li2Lu5O4(BO3)3 phase. J. Lumin. 124(1), 10-14]. In this work the luminescence properties of another borate, namely LSB doped by Yb are presented

  3. High-power mode-locked operation of Yb-doped NaY(WO4)2 end-pumped by laser diodes

    International Nuclear Information System (INIS)

    Passively cw mode-locked laser operation of Yb-doped NaY(WO4)2 (Yb:NaYW) crystal was demonstrated with an average power of 400 mW. This is the highest power achieved from the mode-locked Yb:NaYW laser to our knowledge. The laser was end-pumped by a high power fiber pigtailed laser diode bar and the mode-locking was enabled by a semiconductor saturable absorber mirror (SESAM). The laser pulse duration was 1.1 ps, centered at the wavelength of 1019.7 nm with a bandwidth of 1.6 nm, and nearly transform-limited

  4. Monolithic Yb-fiber femtosecond laser with intracavity all-solid PBG fiber and ex-cavity HC-PCF

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2010-01-01

    (PM) photonic bandgap fiber (PBG) is used in the cavity of the master oscillator for dispersion compensation and stabilization of modelocking. The final compression of an chirped-pulse-amplified laser signal is performed in a hollow PM PCF, yielding final fiber-delivered pulse energy of around 7 n......We demonstrate an all-fiber femtosecond master oscillator / power amplifier operating at the central wavelength of 1033 nm, based on Yb-doped fiber as gain medium, and two different kinds of photonic crystal fibers for dispersion control and stabilization. An all-solid (AS) polarization maintaining...

  5. Enhanced Visible Light Generation from 1 μm Femtosecond Pulses within High-Δ Photonic Crystal Fibers

    International Nuclear Information System (INIS)

    We demonstrate the blue light generated in high-Δ photonic crystal fibers (PCFs). A femtosecond Yb-doped fiber laser, operating at 1039nm, is used to pump a GeO2-doped PCF in the largely anomalous group velocity dispersion (GVD) region. The emitted radiation covers 418.6–544.6nm with 5dB flatness. The calculated result indicates that the cross phase module (XPM) effect induced by higher-mode soliton makes a contribution to the blue component generation. (fundamental areas of phenomenology(including applications))

  6. Characteristics of Soliton Evolution in the Wave-Breaking-Free Regime in a Passively Mode-Locked Yb-Doped Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    WU Ge; TIAN Xiao-Jian; GAO Bo; SHAN Jiang-Dong; RU Yu-Xing

    2011-01-01

    @@ We focus on several aspects concerning the numerical simulation of a passively mode-locked Yb-doped fiber laser by a non-distributed model.The characteristics of soliton evolution in a wave-breaking-free regime are numerically investigated with the split-step Fourier method.Based on the model,a parabolic-shaped soliton with a nearlylinear chirp and bound soliton pairs are obtained by controlling the intra-cavity average dispersion of the fiber laser.A phenomenon is observed that by keeping the system parameters unchanged,linearly chirped parabolic soliton and bound soliton pairs are attainable under different initial conditions in the transient region between these two kinds of solitons.%We focus on several aspects concerning the numerical simulation of a passively mode-locked Yb-doped fiber laser by a non-distributed model. The characteristics of soliton evolution in a wave-breaking-free regime are numerically investigated with the split-step Fourier method. Based on the model, a parabolic-shaped soliton with a nearly linear chirp and bound soliton pairs are obtained by controlling the intra-cavity average dispersion of the fiber laser. A phenomenon is observed that by keeping the system parameters unchanged, linearly chirped parabolic soliton and bound soliton pairs are attainable under different initial conditions in the transient region between these two kinds of solitons.

  7. Density-functional study on the robust ferromagnetism in rare-earth element Yb-doped SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai-Cheng, E-mail: kczhang@yeah.net [College of Mathematics and Physics, Bohai University, Jinzhou 121013 (China); Li, Yong-Feng [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal ResourcesInner Mongolia University of Science and Technology, Baotou 014010 (China); School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Liu, Yong [State Key Laboratory of Metastable Materials Science and Technology and College of Science, Yanshan University, Qinhuangdao, Hebei 066004 (China); Chi, Feng [College of Engineering, Bohai University, Jinzhou 121013 (China)

    2014-06-01

    So far, little has been known about the ferromagnetism induced by p–f hybridization. We investigate the magnetic properties of Yb-doped SnO{sub 2} by first-principles calculations. We find that the doped system favors the ferromagnetic state and a room-temperature ferromagnetism can be expected in it. The origin of ferromagnetism can be attributed to the p–f hybridization between Yb impurity and its surrounding oxygen atoms. The formation energy of defect complex is calculated and the magnetic mediation of intrinsic vacancies is studied. Our results reveal that the formation energy of the defect complex with Sn vacancy is about 7.3 eV lower in energy than that with oxygen vacancy. This means Sn vacancy is much easier to form than oxygen vacancy in the presence of Yb substitution. The ferromagnetism of the doped system is greatly enhanced in the presence of Sn vacancies. - Highlights: • Room-temperature ferromagnetism can be expected in Yb-doped SnO{sub 2}. • The origin of ferromagnetism can be attributed to the p–f hybridization between Yb and O atoms. • Oxygen vacancies are much hard to form and contribute little to the ferromagnetism. • Sn vacancies are easy to form under oxygen-rich condition and stabilize the ferromagnetism effectively.

  8. Luminescent properties of Yb-doped LaSc{sub 3}(BO{sub 3}){sub 4} under VUV excitation

    Energy Technology Data Exchange (ETDEWEB)

    Guerassimova, N.; Kamenskikh, I. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Krasikov, D. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation)], E-mail: kdn@nm.ru; Mikhailin, V. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Zagumennyi, A.; Koutovoi, S.; Zavartsev, Yu. [Laser Crystals Department, General Physics Institute of RAS, Vavilova str. 38, 119991 Moscow (Russian Federation); Pedrini, C. [Laboratoire de Physico-Chimie des Materiaux Luminescents, Universite Claude Bernard Lyon-1, UMR 5620 CNRS, 69622 Villeurbanne (France)

    2007-04-15

    Ytterbium doped borate crystals are promising laser media, e.g. in LaSc{sub 3}(BO{sub 3}){sub 4} (LSB) matrices large distance between ytterbium ions results in reduced concentration quenching of the ytterbium f-f luminescence [Petermann, K., Fagundes-Peters, D., Johansen, O., Mond, M., Peters, V., Romero, J.J., Kutovoi, S., Speiser, J., Giesen, A., 2005. Highly Yb-doped oxides for thin-disc lasers. J. Crystal Growth 275, 135-140]. Yb{sup 3+} ions in complex oxides in addition to the 4f {yields} 4f transitions often manifest fast charge transfer luminescence (CTL) in the UV-visible range. In some borates it was not observed at all, like in orthoborates of Sc, Y and La [Van Pieterson, L., Heeroma, M., de Heer, E., Meijerink, A., 2000. Charge transfer luminescence of Yb{sup 3+}. J. Lumin. 91, 177-193]; in haloborates Sr{sub 2}B{sub 5}O{sub 9}X, where X = Cl, Br, the UV/visible luminescence was attributed to ytterbium CTL though it looked substantially different from other matrices [Dotsenko, V.P., Berezovskaya, I.V., Pyrogenko, P.V., Efryushina, N.P., Rodniy, P.A., Eijk van, C.W.E., Sidorenko, A.V., 2002. Valence states and luminescence properties of ytterbium ions in strontium haloborates. J. Solid State Chem. 166, 271-276]; while in oxyborate Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} 'classical' CTL was observed [Jubera, V., Garcia, A., Chaminade, J.P., Guillen, F., Sablayrolles, Jean, Fouassier, C., 2007. Yb{sup 3+} and Yb{sup 3+}-Eu{sup 3+} luminescent properties of the Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} phase. J. Lumin. 124(1), 10-14]. In this work the luminescence properties of another borate, namely LSB doped by Yb are presented.

  9. Research progress of chelate precursor doping method to fabricate Yb-doped large-mode-area silica fibers for kW-level laser

    Science.gov (United States)

    Wang, Zhen; Zhan, Huan; Ni, Li; Peng, Kun; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2015-11-01

    With continuous efforts and practical managing experiences, the chelate precursor doping method has been justified as an effective way to dope rare-earth ions into silica host materials, a key technique in making large-mode-area silica fibers for high power laser applications. It is characterized by good controllability, stability and repeatability to accomplish different refractive index profiles. Different preforms with a large core, designed refractive index profile, good symmetrical shape and homogeneous elemental distribution were successfully fabricated. The home-made standard 20/400-type double-cladding Yb-doped large-mode-area silica fiber was drawn and presented a 1.6 kW laser output at 1064 nm, the highest power record publically reported with this method. With further optimization, chelate precusor doping method has potential to manufacture high power laser fibers for the next generation.

  10. Characteristics of a low repetition rate passively mode-locked Yb-doped fiber laser in an all-normal dispersion cavity

    International Nuclear Information System (INIS)

    The lasing characteristics of a 365 kHz low repetition rate Yb-doped fiber laser operated in an all-normal dispersion cavity and mode-locked by the nonlinear polarization rotation mechanism are investigated in detail. As the pump power increases, the laser exhibits two transition routes when evolved from the continuous-wave (CW) state to the mode-locked (ML) state. In one evolution route the Q-switched mode-locked (QML) state is sandwiched between the CW and ML states, whereas in the other more interesting evolution route the hysteresis transition between the CW and ML states is found for the first time. Under the mode-locking operation, the laser generates sub-nanosecond pulses with linear dependence of pulsewidth on bandwidth under different pump powers, indicating the presence of giant linear chirps on the laser output pulses. (paper)

  11. All-normal-dispersion passively mode-locked Yb-doped fiber ring laser based on a graphene oxide saturable absorber

    International Nuclear Information System (INIS)

    We have demonstrated an all-normal-dispersion passively mode-locked Yb-doped fiber laser using a graphene oxide/polyvinyl alcohol (GO–PVA) saturable absorber without surfactant, for the first time to the best of our knowledge. The experimental results show that the pulse duration of the mode-locked lasers varies from 191 ps to 1.68 ns, while the cavity round trip time changes from 24 to 458 ns, through the variation of the cavity length. In addition, the proposed passively mode-locked fiber laser demonstrates a maximum average output power of 539 mW with a laser cavity length of 94 m, and the corresponding single pulse energy reaches 0.429 μJ. The proposed mode-locked fiber lasers with large chirp pulses may find potential applications in fiber chirped pulse amplification systems for micromachining, material processing and diagnostic applications. (letter)

  12. Second Harmonic Generation Using an All-Fiber Q-Switched Yb-Doped Fiber Laser and MgO:c-PPLN

    Directory of Open Access Journals (Sweden)

    Yi Gan

    2008-01-01

    Full Text Available We have experimentally demonstrated an efficient all-fiber passively Q-switched Yb-doped fiber laser with Samarium doped fiber as a saturable absorber. Average output power of 3.4 W at a repetition rate of 250 kHz and a pulse width of 1.1 microseconds was obtained at a pump power of 9.0 W. By using this fiber laser system and an MgO-doped congruent periodically poled lithium niobate (MgO:c-PPLN, second harmonic generation (SHG output at 532 nm was achieved at room temperature. The conversion efficiency is around 4.2% which agrees well with the theoretical simulation.

  13. High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

    Science.gov (United States)

    Tan, B; Panchatsharam, S; Venkatakrishnan, K

    2009-03-01

    Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 µm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ~300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 µm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

  14. High repetition rate femtosecond laser forming sub-10 μm diameter interconnection vias

    International Nuclear Information System (INIS)

    Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 μm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ∼300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 μm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

  15. All-fiber 30-μm core diameter Yb-doped pulse-pumped amplifier cascade generating 10 nm-bandwidth 545 kW peak power pulses

    International Nuclear Information System (INIS)

    An electric-pulse-driven super-luminescent diode laser generating 1064 nm wavelength with 37 nm-bandwidth, several nanoseconds pulses at 20 Hz repetition rate was used to seed an amplifier cascade featuring a 30 μm core Yb-doped fiber as the final power amplifier. From this amplifier cascade, we obtained pulse energy from 1.0 to 1.5 mJ depending on different pulse durations with beam quality of M2 1.7; the highest peak power in excess of 545 kW and 10 nm-bandwidth centered at 1064 nm, which is the widest bandwidth of pulsed Yb-doped millijoule fiber amplifier to our knowledge. Moreover, this all-fiber structure has application to many fields

  16. Monolithic Yb-fiber femtosecond laser using photonic crystal fiber

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2008-01-01

    We demonstrate, both experimentally and theoretically, an environmentally stable monolithic all-PM modelocked femtosecond Yb-fiber laser, with laser output pulse compressed in a spliced-on low-loss hollow-core photonic crystal fiber. Our laser provides direct fiber-end delivery of 4 nJ pulses of...

  17. 980-nm all-fiber mode-locked Yb-doped phosphate fiber oscillator based on semiconductor saturable absorber mirror and its amplifier

    Science.gov (United States)

    Li, Ping-Xue; Yao, Yi-Fei; Chi, Jun-Jie; Hu, Hao-Wei; Zhang, Guang-Ju; Liang, Bo-Xing; Zhang, Meng-Meng; Ma, Chun-Mei; Su, Ning

    2016-08-01

    A 980-nm semiconductor saturable absorber mirror (SESAM) mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introduced into the oscillator to obtain a robust and stable mode-locked seed source. When the cavity length is chosen to be 6 m, the oscillator generates an average output power of 3.5 mW and a pulse width of 76.27 ps with a repetition rate of 17.08 MHz. As the cavity length is optimized to short, 4.4-mW maximum output power and 61.15-ps pulse width are produced at a repetition rate of 20.96 MHz. The output spectrum is centered at 980 nm with a narrow spectral bandwidth of 0.13 nm. In the experiment, no undesired amplified spontaneous emission (ASE) nor harmful oscillation around 1030 nm is observed. Moreover, through a two-stage all-fiber-integrated amplifier, an output power of 740 mW is generated with a pulse width of 200 ps. Project supported by the National Natural Science Foundation of China (Grant No. 61205047).

  18. All-normal dispersion passively mode-locked Yb-doped fiber laser using MoS2-PVA saturable absorber

    Science.gov (United States)

    Sathiyan, S.; Velmurugan, V.; Senthilnathan, K.; Babu, P. Ramesh; Sivabalan, S.

    2016-05-01

    We demonstrate the generation of a dissipative soliton in an all-normal dispersion ytterbium (Yb)-doped fiber laser using few-layer molybdenum disulfide (MoS2) as a saturable absorber. The saturable absorber is prepared by mixing few-layer MoS2 solution with polyvinyl alcohol (PVA) to form a free-standing composite film. The modulation depth and saturation intensity of the MoS2-PVA film are 11% and 5.86 MW cm-2, respectively. By incorporating the MoS2 saturable absorber in the fiber laser cavity, the mode-locked pulses are generated with a pulse width of 1.55 ns and a 3 dB spectral bandwidth of 0.9 nm centered at 1037.5 nm. The fundamental repetition rate and the average power are measured as 15.43 MHz and 1.5 mW, respectively. These results reveal the feasibility of deploying liquid-phase exfoliated few-layer MoS2 nanosheets for dissipative soliton generation in the near-IR region.

  19. Sintering of transparent Yb-doped Lu{sub 2}O{sub 3} ceramics using nanopowder produced by laser ablation method

    Energy Technology Data Exchange (ETDEWEB)

    Kijko, V.S. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation); Maksimov, R.N., E-mail: romanmaksimov@e1.ru [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation); Institute of Electrophysics UB RAS, Amundsen St.106, Ekaterinburg 620016 (Russian Federation); Shitov, V.A. [Institute of Electrophysics UB RAS, Amundsen St.106, Ekaterinburg 620016 (Russian Federation); Demakov, S.L.; Yurovskikh, A.S. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation)

    2015-09-15

    Highlights: • Yb:Lu{sub 2}O{sub 3} nanoparticles synthesized by laser ablation method were investigated. • Transparent Yb:Lu{sub 2}O{sub 3} ceramics were fabricated via vacuum and spark plasma sintering. • Highest transmittance was 79.3% at 1080 nm for vacuum sintered Yb:Lu{sub 2}O{sub 3} sample. - Abstract: Transparent Yb-doped Lu{sub 2}O{sub 3} ceramic samples were fabricated via conventional vacuum and spark plasma sintering. Nanoparticles synthesized by laser ablation method were used as starting material. The morphology and phase evolution of the nanopowder were studied by transmission electron microscopy, simultaneous thermal analysis and X-ray diffraction. The obtained nanoparticles exhibited the monoclinic phase and were fully converted into the main cubic phase after calcination at 1100 °C for 1 h. Conventional vacuum sintering of Yb:Lu{sub 2}O{sub 3} powder compact at 1780 °C for 20 h resulted in a fully-dense ceramics with an average grain size of 1.6 μm and optical transmittance of 79.3% at 1080 nm. Spark plasma sintering of the calcined Yb:Lu{sub 2}O{sub 3} nanoparticles at 1450 °C and 15 kN for 40 min led to a 0.2 μm-grained ceramics exhibiting an optical transmittance of 75.6% at 1080 nm.

  20. 超长腔碳纳米管锁模多波长掺镱光纤激光器∗%Ultra-long cavity multi-wavelength Yb-doped fiber laser mode-locked by carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    王玉宝; 齐晓辉; 沈阳; 姚繄蕾; 徐志敬; 潘玉寨

    2015-01-01

    We demonstrate an ultra-long cavity multi-wavelength Yb-doped fiber laser mode-locked by carbon nanotubes. The total length of the fiber laser is 1021.2 m. The different regimes of noise-like soliton and soliton rain mode-locking with the multi-wavelength operation are experimentally obtained with a repetition rate of 199.8 kHz. The higher output power and pulse energy from the soliton rain are measured to be 40.3 mW and 201.5 nJ, respectively, with a pulse width of about 102.5 ns.

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

    Science.gov (United States)

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

    2015-08-24

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

  2. High pulse energy femtosecond large-mode-area photonic crystal fiber laser

    Institute of Scientific and Technical Information of China (English)

    SONG YouJian; HU MingLie; ZHANG Chi; CHAI Lu; WANG ChingYue

    2008-01-01

    A high pulse energy femtosecond fiber laser based on a large-mode-area photonic crystal fiber is demonstrated. A segment of Yb-doped single-polarization large-mode-area photonic crystal fiber with extremely low nonlinearity is explored as gain media of this fiber laser, resulting in intrinsically environmentally stability. The fiber laser is based on a linear cavity with dispersion compensation free configuration, and the stable mode-locking is obtained by a semiconductor saturable absorber mirror (SESAM). The fiber laser directly generates 2.5 W of average power at a repetition rate of 51.4 MHz,corresponding to a single pulse energy of 50 nJ. The output pulse duration is 4.2 ps, which is dechirped to 410 fs after extracavity dispersion compensation. The nonlinear absorption of SESAM determines the pulse shaping at low output power, while the mode-locking mechanism is under the balance between spectrum broadening from self-phase-modulation and gain filtering at the high output power.

  3. 948 kHz repetition rate, picosecond pulse duration, all-PM 1.03 μm mode-locked fiber laser based on nonlinear polarization evolution

    Science.gov (United States)

    Boivinet, S.; Lecourt, J.-B.; Hernandez, Y.; Fotiadi, A.; Mégret, P.

    2014-05-01

    We present in this study a PM all-fiber laser oscillator passively mode-locked (ML) at 1.03 μm. The laser is based on Nonlinear Polarization Evolution (NPE) in polarization maintaining (PM) fibers. In order to obtain the mode-locking regime, a nonlinear reflective mirror including a fibered polarizer, a long fiber span and a fibered Faraday mirror (FM) is inserted in a Fabry-Perot laser cavity. In this work we explain the principles of operation of this original laser design that permits to generate ultrashort pulses at low repetition (lower that 1MHz) rate with a cavity length of 100 m of fiber. In this experiment, the measured pulse duration is about 6 ps. To our knowledge this is the first all-PM mode-locked laser based on the NPE with a cavity of 100m length fiber and a delivered pulse duration of few picosecondes. Furthermore, the different mode-locked regimes of the laser, i.e. multi-pulse, noise-like mode-locked and single pulse, are presented together with the ways of controlling the apparition of these regimes. When the single pulse mode-locking regime is achieved, the laser delivers linearly polarized pulses in a very stable way. Finally, this study includes numerical results which are obtained with the resolution of the NonLinear Schrodinger Equations (NLSE) with the Split-Step Fourier (SSF) algorithm. This modeling has led to the understanding of the different modes of operation of the laser. In particular, the influence of the peak power on the reflection of the nonlinear mirror and its operation are studied.

  4. Femtosecond laser spectroscopy

    CERN Document Server

    Hannaford, Peter

    2005-01-01

    As concepts and methodologies have evolved over the past two decades, the realm of ultrafast science has become vast and exciting and has impacted many areas of chemistry, biology and physics, and other fields such as materials science, electrical engineering, and optical communication. The field has recently exploded with the announcement of a series of remarkable new developments and advances. This volume surveys this recent growth in eleven chapters written by leading international researchers in the field. It includes sections on femtosecond optical frequency combs, soft x-ray femtosecond laser sources, and attosecond laser sources. In addition, the contributors address real-time spectroscopy of molecular vibrations with sub-5-fs pulses and multidimensional femtosecond coherent spectroscopies for studying molecular and electron dynamics. Novel methods for measuring and characterizing ultrashort laser pulses and ultrashort pulses of light are also described. The topics covered are revolutionizing the field...

  5. Femtosecond Laser Filamentation

    CERN Document Server

    Chin, See Leang

    2010-01-01

    Femtosecond Laser Filamentation gives a comprehensive review of the physics of propagation of intense femtosecond laser pulses in optical media (principally air) and the applications and challenges of this new technique. This book presents the modern understanding of the physics of femtosecond laser pulse propagation, including unusual new effects such as the self-transformation of the pulse into a white light laser pulse, intensity clamping, the physics of multiple filamentation and competition, and how filaments’ ability to melt glass leads to wave guide writing. The potential applications of laser filamentation in atmospheric sensing and the generation of other electromagnetic pulses from the UV to the radio frequency are treated, together with possible future challenges in the excitation of super-excited states of molecules. Exciting new phenomena such as filament induced ultrafast birefringence and the excitation of molecular rotational wave packets and their multiple revivals in air (gases) will also ...

  6. Compact fixed wavelength femtosecond oscillators as an add-on for tunable Ti:sapphire lasers extend the range of applications towards multimodal imaging and optogenetics

    Science.gov (United States)

    Hakulinen, T.; Klein, J.

    2016-03-01

    Two-photon (2P) microscopy based on tunable Ti:sapphire lasers has become a widespread tool for 3D imaging with sub-cellular resolution in living tissues. In recent years multi-photon microscopy with simpler fixed-wavelength femtosecond oscillators using Yb-doped tungstenates as gain material has raised increasing interest in life-sciences, because these lasers offer one order of magnitude more average power than Ti:sapphire lasers in the wavelength range around 1040 nm: Two-photon (2P) excitation of mainly red or yellow fluorescent dyes and proteins (e.g. YFP, mFruit series) simultaneously has been proven with a single IR laser wavelength. A new approach is to extend the usability of existing tunable Titanium sapphire lasers by adding a fixed IR wavelength with an Yb femtosecond oscillator. By that means a multitude of applications for multimodal imaging and optogenetics can be supported. Furthermore fs Yb-lasers are available with a repetition rate of typically 10 MHz and an average power of typically 5 W resulting in pulse energy of typically 500 nJ, which is comparably high for fs-oscillators. This makes them an ideal tool for two-photon spinning disk laser scanning microscopy and holographic patterning for simultaneous photoactivation of large cell populations. With this work we demonstrate that economical, small-footprint Yb fixed-wavelength lasers can present an interesting add-on to tunable lasers that are commonly used in multiphoton microscopy. The Yb fs-lasers hereby offer higher power for imaging of red fluorescent dyes and proteins, are ideally enhancing existing Ti:sapphire lasers with more power in the IR, and are supporting pulse energy and power hungry applications such as spinning disk microscopy and holographic patterning.

  7. Femtosecond Laser Nonlinear Lithography

    OpenAIRE

    Nishiyama, Hiroaki; Hirata, Yoshinori

    2010-01-01

    In this chapter, we presented the fundamentals of femtosecond laser nonlinear lithography and demonstrated the fabrication of three-dimensional surfaces of inorganic materials using FLAM. We can write complex structures directly inside resists using TPA. Simultaneously, high spatial resolution below the diffraction limit was achievable in spite of low-NA focusing. Using such unique properties, the semiconductor fabrication technology was extended to microfabrication on non-flat substrates. Op...

  8. Femtosecond laser cataract surgery

    OpenAIRE

    Nagy, Zoltan Z.; McAlinden, Colm

    2015-01-01

    Femtosecond laser (FSL) cataract surgery is in its infancy but is rapidly gaining popularity due to the improved consistency and predictability for corneal incisions and anterior capsulorhexis. It enables subsequently less phacoemulsification energy and time to be employed, which has gains in terms of reduced corneal oedema. In addition, the FSL allows better circularity of the anterior capsulotomy, capsule overlap, intraocular lens (IOL) placement and centration of the IOL. These advantages ...

  9. Femtosecond laser materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, B. C., LLNL

    1998-06-02

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

  10. Femtosecond laser materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, B

    1998-08-05

    Femtosecond lasers enable materials processing of most any material with extremely high precision and negligible shock or thermal loading to the surrounding area. Applications ranging from drilling teeth to cutting explosives to precision cuts in composites are possible by using this technology. For material removal at reasonable rates, we have developed a fully computer-controlled 15-Watt average power, 100-fs laser machining system.

  11. femtosecond laser ablation

    OpenAIRE

    Margetic, Vanja

    2003-01-01

    Femtosecond laser ablation was investigated as a solid sampling method for elemental chemical analysis. In comparison to the sampling with longer laser pulses, two aspects could be improved by using ultrashort pulses: elimination of the elemental fractionation from the ablation crater, which is necessary for an accurate quantitative analysis, and better control of the material removal (especially for metals), which increases the spatial resolution of microanalysis. Basic aspects of ultrashort...

  12. Advances in femtosecond laser technology

    Science.gov (United States)

    Callou, Thais Pinheiro; Garcia, Renato; Mukai, Adriana; Giacomin, Natalia T; de Souza, Rodrigo Guimarães; Bechara, Samir J

    2016-01-01

    Femtosecond laser technology has become widely adopted by ophthalmic surgeons. The purpose of this study is to discuss applications and advantages of femtosecond lasers over traditional manual techniques, and related unique complications in cataract surgery and corneal refractive surgical procedures, including: LASIK flap creation, intracorneal ring segment implantation, presbyopic treatments, keratoplasty, astigmatic keratotomy, and intrastromal lenticule procedures. PMID:27143847

  13. Femtosecond laser cataract surgery.

    Science.gov (United States)

    Nagy, Zoltan Z; McAlinden, Colm

    2015-01-01

    Femtosecond laser (FSL) cataract surgery is in its infancy but is rapidly gaining popularity due to the improved consistency and predictability for corneal incisions and anterior capsulorhexis. It enables subsequently less phacoemulsification energy and time to be employed, which has gains in terms of reduced corneal oedema. In addition, the FSL allows better circularity of the anterior capsulotomy, capsule overlap, intraocular lens (IOL) placement and centration of the IOL. These advantages have resulted in improved visual and refractive outcomes in the short term. Complication rates are low which reduce with surgeon experience. This review article focuses on the Alcon LenSx system. PMID:26605364

  14. Femtosecond Stimulated Raman Spectroscopy.

    Science.gov (United States)

    Dietze, Daniel R; Mathies, Richard A

    2016-05-01

    Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast nonlinear optical technique that provides vibrational structural information with high temporal (sub-50 fs) precision and high spectral (10 cm(-1) ) resolution. Since the first full demonstration of its capabilities ≈15 years ago, FSRS has evolved into a mature technique, giving deep insights into chemical and biochemical reaction dynamics that would be inaccessible with any other technique. It is now being routinely applied to virtually all possible photochemical reactions and systems spanning from single molecules in solution to thin films, bulk crystals and macromolecular proteins. This review starts with an historic overview and discusses the theoretical and experimental concepts behind this technology. Emphasis is put on the current state-of-the-art experimental realization and several variations of FSRS that have been developed. The unique capabilities of FSRS are illustrated through a comprehensive presentation of experiments to date followed by prospects. PMID:26919612

  15. Femtosecond laser Kerr microscopy

    International Nuclear Information System (INIS)

    We present a new femtosecond laser Kerr microscope which has both scanning and full-field imaging capabilities. This instrument combines a lateral resolution in the sub-micrometer regime with a temporal resolution of better than 100 fs. The magnetic sample is thermally pumped by the fundamental beam and probed by the frequency-doubled beam via the magneto-optical Kerr effect (MOKE) in polar or longitudinal geometry. Double lock-in technique using a photo-elastic modulator (50 kHz) and an optical chopper (80 Hz) leads to very high sensitivity. In the scanning mode a three-axis piezo stage with a sub-nanometer resolution and 400 μm scan range in all directions is used. Full-field Kerr microscopy is possible by destroying the lateral coherence of the laser light with a rotating disc and detecting the image with a CCD camera. A cryostat allows measurements in the temperature range from 3.5 to 450 K. Instrument controlling software, developed on Visual Studio.Net, enables multi-dimensional scans, e.g., the MOKE signal can be recorded for arbitrary combination of six parameters (sample position, magnetic field, pump-probe delay time, and temperature). First time-resolved studies on Fe/Gd, Co/Ni and Co/Pt multilayer systems are presented

  16. Effect of Sintering Temperature on Microstructure, Chemical Stability and Electrical Properties of Transition Metal or Yb-Doped BaZr0.1Ce0.7Y0.1M0.1O3-δ (M = Fe, Ni, Co and Yb

    Directory of Open Access Journals (Sweden)

    Behzad eMirfakhraei

    2014-03-01

    Full Text Available Perovskite-type BaZr0.1Ce0.7Y0.1M0.1O3-δ (M = Fe, Ni, Co and Yb (BZCY-M oxides were synthesized using the conventional solid-state reaction method at 1350-1550 oC in air in order to investigate the effect of dopants on sintering, crystal structure, chemical stability under CO2 and H2S, and electrical transport properties. The formation of the single-phase perovskite-type structure with an orthorhombic space group Imam was confirmed by Rietveld refinement using powder X-ray diffraction (PXRD for the Fe, Co, Ni and Yb-doped samples. The BZCY-Co and BZCY-Ni oxides show a total electrical conductivity of 0.01 and 8 × 10-3 Scm-1 at 600 oC in wet H2 with an activation energy of 0.36 and 0.41 eV, respectively. Scanning electron microscopy (SEM and energy-dispersive X-ray analysis (EDX revealed Ba and Co rich secondary phase at the grain-boundaries, which may explain the enhancement in the total conductivity of the BZCY-Co. However, ex-solution of Ni at higher sintering temperatures, especially at 1550 oC, decreases the total conductivity of the BZCY-Ni material. The Co and Ni dopants act as a sintering aid and form dense pellets at a lower sintering temperature of 1250 oC. The Fe, Co and Ni-doped BZCY-M samples synthesized at 1350 oC show stability in 30 ppm H2S/H2 at 800 oC, and increasing the firing temperature to 1550 oC, enhanced the chemical stability in CO2 / N2 (1: 2 at 25-900 oC. The BZCY-Co and Ni compounds with high conductivity in wet H2 could be considered as possible anodes for intermediate temperature solid oxide fuel cells (IT-SOFCs.

  17. Advances in femtosecond laser technology

    Directory of Open Access Journals (Sweden)

    Callou TP

    2016-04-01

    Full Text Available Thais Pinheiro Callou, Renato Garcia, Adriana Mukai, Natalia T Giacomin, Rodrigo Guimarães de Souza, Samir J Bechara Department of Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil Abstract: Femtosecond laser technology has become widely adopted by ophthalmic surgeons. The purpose of this study is to discuss applications and advantages of femtosecond lasers over traditional manual techniques, and related unique complications in cataract surgery and corneal refractive surgical procedures, including: LASIK flap creation, intracorneal ring segment implantation, presbyopic treatments, keratoplasty, astigmatic keratotomy, and intrastromal lenticule procedures. Keywords: laser therapy, refractive surgical procedures, intracorneal ring, laser in situ keratomileusis, keratoplasty, presbyopia, cataract extraction, astigmatism surgery

  18. Holographic vector-wave femtosecond laser processing

    Science.gov (United States)

    Hayasaki, Yoshio; Hasegawa, Satoshi

    2016-03-01

    Arbitrary and variable beam shaping of femtosecond pulses by a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM) have been applied to femtosecond laser processing. The holographic femtosecond laser processing has been widely used in many applications such as two-photon polymerization, optical waveguide fabrication, fabrication of volume phase gratings in polymers, and surface nanostructuring. A vector wave that has a spatial distribution of polarization states control of femtosecond pulses gives good performances for the femtosecond laser processing. In this paper, an in- system optimization of a CGH for massively-parallel femtosecond laser processing, a dynamic control of spatial spectral dispersion to improve the focal spot shape, and the holographic vector-wave femtosecond laser processing are demonstrated.

  19. Femtosecond laser in laser in situ keratomileusis

    OpenAIRE

    Salomão, Marcella Q.; Wilson, Steven E.

    2010-01-01

    Flap creation is a critical step in laser in situ keratomileusis (LASIK). Efforts to improve the safety and predictability of the lamellar incision have fostered the development of femtosecond lasers. Several advantages of the femtosecond laser over mechanical microkeratomes have been reported in LASIK surgery. In this article, we review common considerations in management and complications of this step in femtosecond laser–LASIK and concentrate primarily on the IntraLase laser because most p...

  20. High power radially-polarized Yb-doped fiber laser

    OpenAIRE

    Lin, Di; Daniel, J. M. O.; Gecevičius, M.; Beresna, M; Kazansky, P. G.; Clarkson, W. A.

    2014-01-01

    A simple technique for directly generating a radially-polarized output beam from an ytterbium-doped fiber laser using an intracavity spatially-variant waveplate is reported. The laser yielded 32W of output with a corresponding slope efficiency of 65.8% in a radially-polarised beam with beam propagation factor ~2.1 and polarization purity >95%

  1. Yb-doped glass microcavity laser operation in water

    OpenAIRE

    Ostby, Eric P.; Vahala, Kerry J.

    2009-01-01

    A ytterbium-doped silica microcavity laser demonstrates stable laser emission while completely submerged in water. To our knowledge, it is the first solid-state laser whose cavity mode interacts with water. The device generates more than 2 μW of output power. The laser performance is presented, and low-concentration biosensing is discussed as a potential application.

  2. Scintillation properties of Yb-doped yttrium-aluminum garnets

    International Nuclear Information System (INIS)

    Relative light yield (LY) dependence on temperature for Yb:YAG crystals containing 10% to 100% of Yb dopant is studied for γ and α excitation. The maximum LY is achieved at 120 K3 Ph/MeV at T=140 K for (Yb 25%) YAG. Linearity of the light output is checked. α/γ ratio is found to be 0.42±0.02. Pulse shapes induced by γ and α particles and cosmic rays are investigated by analysing a set of single events recorded. γ events are fast (τ<4 ns), while other kinds of radiation give rise to more complicated and longer profiles, allowing particle discrimination. Dependence of scintillation properties on concentration of Yb and purity is discussed

  3. Preparation and Characterization of Yb - doped YAG Ceramics

    OpenAIRE

    Hostasa, Jan; Esposito, Laura; Alderighi, Daniele; Pirri, Angela

    2011-01-01

    Rare-earth doped yttrium aluminum garnet (YAG) ceramics are among the most widely produced transparent ceramics for laser applications. Yb:YAG ceramics are an interesting IR laser material [1], which allows significantly higher doping compared to the generally more used Nd:YAG [2,3]. This work presents the preparation of polycrystalline Yb:YAG ceramics with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray ...

  4. Preparation and characterization of Yb-doped YAG ceramics

    Science.gov (United States)

    Hostaša, Jan; Esposito, Laura; Alderighi, Daniele; Pirri, Angela

    2013-02-01

    This work presents the results of the preparation of polycrystalline Yb:YAG ceramics for laser sources with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray dried mixture of pure oxide powders with TEOS as a sintering aid. Sintering was conducted under high vacuum and clean atmosphere. Various sintering cycles were tested, so that optimum conditions could be selected in dependence on Yb concentration. Samples with optical transmittance higher than 80% were prepared and their laser performance was examined. Slope efficiency as high as 73% and a maximum output power of 6 W were obtained for the sample doped with 10% Yb. Final microstructure of prepared samples was analyzed via optical microscopy, scanning and transmission electron microscopy, and EDS.

  5. Femtosecond Photon-Counting Receiver

    Science.gov (United States)

    Krainak, Michael A.; Rambo, Timothy M.; Yang, Guangning; Lu, Wei; Numata, Kenji

    2016-01-01

    An optical correlation receiver is described that provides ultra-precise distance and/or time/pulse-width measurements even for weak (single photons) and short (femtosecond) optical signals. A new type of optical correlation receiver uses a fourth-order (intensity) interferometer to provide micron distance measurements even for weak (single photons) and short (femtosecond) optical signals. The optical correlator uses a low-noise-integrating detector that can resolve photon number. The correlation (range as a function of path delay) is calculated from the variance of the photon number of the difference of the optical signals on the two detectors. Our preliminary proof-of principle data (using a short-pulse diode laser transmitter) demonstrates tens of microns precision.

  6. Nanoflow electrospinning serial femtosecond crystallography

    International Nuclear Information System (INIS)

    A low flow rate liquid microjet method for delivery of hydrated protein crystals to X-ray lasers is presented. Linac Coherent Light Source data demonstrates serial femtosecond protein crystallography with micrograms, a reduction of sample consumption by orders of magnitude. An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min−1 to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min−1 and diffracted to beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption

  7. Femtosecond single-electron diffraction

    Directory of Open Access Journals (Sweden)

    S. Lahme

    2014-05-01

    Full Text Available Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration.

  8. Designing the femtosecond optical oscilloscope

    Science.gov (United States)

    Toneyan, H.; Sukiasyan, M.; Zeytunyan, A.; Tsakanov, V.; Mouradian, L.

    2016-01-01

    We present the results of our recent experimental and numerical studies on femtosecond pulse spectrotemporal imaging in a similariton-induced temporal lens aimed to designing a femtosecond optical oscilloscope [1]. We have studied nonlinear and dispersive peculiarities of modern high-tech materials, such as photonic crystal fibers, hollow-core fibers etc, to use them in the scheme, and to provide compactness and reliability of the device. The use of hollow-core fibers, as a dispersive medium instead of a pair of prisms or gratings, is of special importance for constructing the industrial tool. Additionally, we are experimenting on the method of dispersive Fourier transformation, using the effect of chromo-modal dispersion in multimode fibers [2], to provide real-time performance of the device.

  9. Third-generation femtosecond technology

    OpenAIRE

    Fattahi, Hanieh

    2015-01-01

    Chirped pulse amplification in solid-state lasers is currently the method of choice for producing high-energy ultrashort pulses, having surpassed the performance of dye lasers over 20 years ago. The third generation of femtosecond technology based on short-pulse-pumped optical parametric chirped pulse amplification (OPCPA) holds promise for providing few-cycle pulses with terawatt-scale peak powers and kilowatt-scale-average powers simultaneously, heralding the next wave of ...

  10. Nanoflow electrospinning serial femtosecond crystallography.

    Science.gov (United States)

    Sierra, Raymond G; Laksmono, Hartawan; Kern, Jan; Tran, Rosalie; Hattne, Johan; Alonso-Mori, Roberto; Lassalle-Kaiser, Benedikt; Glöckner, Carina; Hellmich, Julia; Schafer, Donald W; Echols, Nathaniel; Gildea, Richard J; Grosse-Kunstleve, Ralf W; Sellberg, Jonas; McQueen, Trevor A; Fry, Alan R; Messerschmidt, Marc M; Miahnahri, Alan; Seibert, M Marvin; Hampton, Christina Y; Starodub, Dmitri; Loh, N Duane; Sokaras, Dimosthenis; Weng, Tsu-Chien; Zwart, Petrus H; Glatzel, Pieter; Milathianaki, Despina; White, William E; Adams, Paul D; Williams, Garth J; Boutet, Sébastien; Zouni, Athina; Messinger, Johannes; Sauter, Nicholas K; Bergmann, Uwe; Yano, Junko; Yachandra, Vittal K; Bogan, Michael J

    2012-11-01

    An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14-3.1 µl min(-1) to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min(-1) and diffracted to beyond 4 Å resolution, producing 14,000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption. PMID:23090408

  11. Femtosecond Laser Cutting of Graphene

    OpenAIRE

    Zhang, Wen

    2012-01-01

    Graphene is a single atomic layer 2D graphite that has unusual properties that would open up wide industrial applications. As graphite is the toughest material on earth, challenges exist to cut and shape the materials. This MPhil thesis presents the outcome of femtosecond laser micro-patterning of single layer graphene on a glass substrate, which has resulted in a journal publication. A literature review was carried out to understand the process, basic characteristics and challenges in laser ...

  12. Compression of chirp pulses from a femtosecond fiber based amplifier

    Science.gov (United States)

    Ito, Rumi; Takiuchi, Ken-ichi; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jyun; Sumida, Shin

    2015-03-01

    We demonstrate a single mode fiber based master oscillator power amplifier (MOPA) with a single polarization and a fully monolithic design. We have built a passive mode-locked polarization maintaining Yb doped fiber as the master oscillator contains a semiconductor saturable absorber mirror and a chirped fiber Bragg grating for the dispersion management. The net intracavity dispersion was managed to be slightly anomalous. The oscillator generates the 150 fs (sech2) pulses at the center wavelength of 1065 nm, and the repetition rate of 42 MHz. The oscillator output was amplified to 1.4 W from 80 mW in the single stage fiber amplifier which results in pulse shape distortion. The pulse shaping with a band pass filter and a compressor was applied to the amplified pulses. The shaping pulses have the pulse width of 90 fs and the pulse energy of 16 nJ.

  13. Molecular fragmentation induced by a femtosecond laser

    Science.gov (United States)

    Kosmidis, Constantine E.; Ledingham, Kenneth W. D.; Kilic, H. S.; McCanny, T.; Singhal, Raghunandan P.; Smith, D.; Langley, Andrew J.

    1998-07-01

    The 90 femtosecond laser induced fragmentation at 375 nm for a number of different nitro-molecules is compared to that induced by a nanosecond laser at the same wavelength by means of time-of-flight mass spectrometry. The potential of femtosecond laser mass spectrometry for analytical purposes is discussed.

  14. Micromachining of Silicon Carbide using femtosecond lasers

    Energy Technology Data Exchange (ETDEWEB)

    Farsari, M [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, PO Box 1527, 71110 Heraklion, Crete (Greece); Filippidis, G [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, PO Box 1527, 71110 Heraklion, Crete (Greece); Zoppel, S [Vienna University of Technology, Photonics Institute, Gusshausstr. 27-29/387, 1040 Vienna (Austria); Reider, G A [Vienna University of Technology, Photonics Institute, Gusshausstr. 27-29/387, 1040 Vienna (Austria); Fotakis, C [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, PO Box 1527, 71110 Heraklion, Crete (Greece)

    2007-04-15

    We have demonstrated micromachining of bulk 3C silicon carbide (3C- SiC) wafers by employing 1028nm wavelength femtosecond laser pulses of energy less than 10 nJ directly from a femtosecond laser oscillator, thus eliminating the need for an amplified system and increasing the micromachining speed by more than four orders of magnitude.

  15. Micromachining of Silicon Carbide using femtosecond lasers

    International Nuclear Information System (INIS)

    We have demonstrated micromachining of bulk 3C silicon carbide (3C- SiC) wafers by employing 1028nm wavelength femtosecond laser pulses of energy less than 10 nJ directly from a femtosecond laser oscillator, thus eliminating the need for an amplified system and increasing the micromachining speed by more than four orders of magnitude

  16. All-fiber femtosecond Cherenkov source

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe Visbech;

    2013-01-01

    An all-fiber femtosecond Cherenkov radiation source is demonstrated for the first time, to the best of our knowledge. Using a stable monolithic femtosecond Ybdoped fiber laser as the pump source, and the combination of photonic crystal fibers as the wave-conversion medium, we have generated tunable...... Cherenkov radiation at visible wavelengths 580 - 630 nm, with pulse duration of sub-160 fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such femtosecond source can find applications in practical biophotonics such as bio-imaging and microscopy....

  17. All-fiber femtosecond Cherenkov source

    Directory of Open Access Journals (Sweden)

    Tu H.

    2013-03-01

    Full Text Available An all-fiber femtosecond Cherenkov radiation source is demonstrated for the first time, to the best of our knowledge. Using a stable monolithic femtosecond Ybdoped fiber laser as the pump source, and the combination of photonic crystal fibers as the wave-conversion medium, we have generated tunable Cherenkov radiation at visible wavelengths 580 – 630 nm, with pulse duration of sub-160 fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such femtosecond source can find applications in practical biophotonics such as bio-imaging and microscopy.

  18. All-fiber femtosecond Cherenkov source

    OpenAIRE

    Tu H.; Møller U.; Lægsgaard J.; Liu X.; Boppart S. A.; Turchinovich D.

    2013-01-01

    An all-fiber femtosecond Cherenkov radiation source is demonstrated for the first time, to the best of our knowledge. Using a stable monolithic femtosecond Ybdoped fiber laser as the pump source, and the combination of photonic crystal fibers as the wave-conversion medium, we have generated tunable Cherenkov radiation at visible wavelengths 580 – 630 nm, with pulse duration of sub-160 fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such femtosecond source can find applications in pra...

  19. The art of femtosecond laser writing

    OpenAIRE

    Kazansky, Peter G.; Yang, Weijia; Shimotsuma, Yasuhiko; Hirao, Kazuyuki; Arai, Alan; Svirko, Yuri P.

    2009-01-01

    Common beliefs that laser writing does not change when reversing beam scan or propagation direction are challenged. Recently discovered phenomena of quill and non-reciprocal femtosecond laser writing in glasses and crystals are reviewed

  20. Avant-garde femtosecond laser writing

    OpenAIRE

    Kazansky, Peter G.; Beresna, Martynas; Shimotsuma, Yasuhiko; Hirao, Kazuyuki; Svirko, Yuri P.; Aktürk, Selcuk

    2010-01-01

    Recently discovered phenomena of quill and non-reciprocal femtosecond laser writing in glasses and crystals are reviewed. Common beliefs that laser writing does not change when reversing beam scan or propagation direction are challenged

  1. Generation of Femtosecond Electron and Photon Pulses

    CERN Document Server

    Thongbai, Chitrlada; Kangrang, Nopadol; Kusoljariyakul, Keerati; Rhodes, Michael W; Rimjaem, Sakhorn; Saisut, Jatuporn; Vilaithong, Thiraphat; Wichaisirimongkol, Pathom; Wiedemann, Helmut

    2005-01-01

    Femtosecond electron and photon pulses become a tool of interesting important to study dynamics at molecular or atomic levels. Such short pulses can be generated from a system consisting of an RF-gun with a thermionic cathode, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The femtosecond electron pulses can be used directly or used as sources to produce electromagnetic radiation of equally short pulses by choosing certain kind of radiation pruduction processes. At the Fast Neutron Research Facility (Thailand), we are especially interested in production of radiation in Far-infrared and X-ray regime. In the far-infrared wavelengths which are longer than the femtosecond pulse length, the radiation is emitted coherently producing intense radiation. In the X-ray regime, development of femtosecond X-ray source is crucial for application in ultrafast science.

  2. Construction of a femtosecond laser microsurgery system

    OpenAIRE

    Steinmeyer, Joseph D; Gilleland, Cody L.; Pardo-Martin, Carlos; Angel, Matthew; Rohde, Christopher B.; Scott, Mark A.; Yanik, Mehmet Fatih

    2010-01-01

    Femtosecond laser microsurgery is a powerful method for studying cellular function, neural circuits, neuronal injury and neuronal regeneration because of its capability to selectively ablate sub-micron targets in vitro and in vivo with minimal damage to the surrounding tissue. Here, we present a step-by-step protocol for constructing a femtosecond laser microsurgery setup for use with a widely available compound fluorescence microscope. The protocol begins with the assembly and alignment of b...

  3. Femtosecond Laser Induced Underwater Superoleophobic Surfaces

    OpenAIRE

    Yong Jiale; Chen Feng; Yang Qing

    2015-01-01

    Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. Silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to the fish’s scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° for the 1,2-dichloroethane droplets in water. Besides, the surface exhibits ultralow oil-adhesio...

  4. Femtosecond optical studies of cuprates

    Science.gov (United States)

    Schneider, Michael L.; Rast, S.; Onellion, Marshall; Demsar, Jure; Taylor, Antoinette J.; Glinka, Yu D.; Tolk, Norman H.; Ren, Yuhang; Luepke, Gunter; Klimov, A.; Xu, Ying; Sobolewski, Roman; Si, Weidong; Zeng, X. H.; Soukiassian, A.; Xi, Xiaoxing; Abrecht, M.; Ariosa, Daniel; Pavuna, Davor; Manzke, Recardo; Printz, J. O.; Parkhurst, D. K.; Downum, K. E.; Guptasarma, P.; Bozovic, Ivan

    2002-11-01

    Femtosecond optical reflectivity measurements of La2-xSrxCuO4, La2CuO4+y, Bi2Sr2CuO6+z and Bi2Sr2CaCu2O8+δ thin films and single crystal samples indicate qualitative changes with fluence. At the lowest fluencies, there is a power law divergence in the relaxation time. The divergence has an onset temperature of 55+/-15K, independent of whether the sample is in the superconducting or normal states. At slightly higher fluencies, still perturbative, the additional response does not exhibit this power law divergence. At quite high fluencies- no longer perturbative- the metallic samples exhibit oscillations in the reflectivity amplitude. The period of these oscillations varies with the probe wavelength but not with the pump wavelength. The oscillations exhibit a decay time as long as 10 nsec.

  5. 2 micron femtosecond fiber laser

    Science.gov (United States)

    Liu, Jian; Wan, Peng; Yang, Lihmei

    2014-07-29

    Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

  6. Massively parallel femtosecond laser processing.

    Science.gov (United States)

    Hasegawa, Satoshi; Ito, Haruyasu; Toyoda, Haruyoshi; Hayasaki, Yoshio

    2016-08-01

    Massively parallel femtosecond laser processing with more than 1000 beams was demonstrated. Parallel beams were generated by a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The key to this technique is to optimize the CGH in the laser processing system using a scheme called in-system optimization. It was analytically demonstrated that the number of beams is determined by the horizontal number of pixels in the SLM NSLM that is imaged at the pupil plane of an objective lens and a distance parameter pd obtained by dividing the distance between adjacent beams by the diffraction-limited beam diameter. A performance limitation of parallel laser processing in our system was estimated at NSLM of 250 and pd of 7.0. Based on these parameters, the maximum number of beams in a hexagonal close-packed structure was calculated to be 1189 by using an analytical equation. PMID:27505815

  7. Femtosecond x-ray pulses from a synchrotron

    OpenAIRE

    Schoenlein, R. W.; Chong, H. H. W.; Glover, T. E.; Heimann, P. A.; Shank, C. V.; Zholents, A.A.; Zolotorev, M.S.

    2000-01-01

    An important frontier in ultrafast science is the application of femtosecond x-ray pulses to the study of structural dynamics in condensed matter. We show that femtosecond laser pulses can be used to generate high-brightness, tunable, femtosecond x-ray pulses from a synchrotron. Performance of existing and proposed femtosecond x-ray beamlines at the Advanced Light Source synchrotron are discussed.

  8. Femtosecond lasers for microsurgery of cornea

    Energy Technology Data Exchange (ETDEWEB)

    Vartapetov, Sergei K; Khudyakov, D V; Lapshin, Konstantin E; Obidin, Aleksei Z; Shcherbakov, Ivan A

    2012-03-31

    The review of femtosecond laser installations for medical applications is given and a new femtosecond ophthalmologic system for creation of a flap of corneal tissue during the LASIK operation is described. An all-fibre femtosecond laser emitting {approx}400-fs pulses at 1067 nm is used. The pulse repetition rate can vary from 200 kHz up to 1 MHz. The output energy of the femtosecond system does not exceed 1 {mu}J. A specially developed objective with small spherical and chromatic aberrations is applied to focus laser radiation to an area of an eye cornea. The size of the focusing spot does not exceed 3 {mu}m. To process the required area, scanning by a laser beam is applied with a speed no less than 5 m s{sup -1}. At a stage of preliminary tests of the system, the {Kappa}8 glass, organic PMMA glass and specially prepared agarose gels are used as a phantom of an eye. The femtosecond system is successfully clinically tested on a plenty of eyes of a pig and on several human eyes. The duration of the procedure of creation of a corneal flap does not exceed 20 s.

  9. Femtosecond Laser Filamentation for Atmospheric Sensing

    Directory of Open Access Journals (Sweden)

    Huai Liang Xu

    2010-12-01

    Full Text Available Powerful femtosecond laser pulses propagating in transparent materials result in the formation of self-guided structures called filaments. Such filamentation in air can be controlled to occur at a distance as far as a few kilometers, making it ideally suited for remote sensing of pollutants in the atmosphere. On the one hand, the high intensity inside the filaments can induce the fragmentation of all matters in the path of filaments, resulting in the emission of characteristic fluorescence spectra (fingerprints from the excited fragments, which can be used for the identification of various substances including chemical and biological species. On the other hand, along with the femtosecond laser filamentation, white-light supercontinuum emission in the infrared to UV range is generated, which can be used as an ideal light source for absorption Lidar. In this paper, we present an overview of recent progress concerning remote sensing of the atmosphere using femtosecond laser filamentation.

  10. Femtosecond laser micromachining of fused silica molds.

    Science.gov (United States)

    Madani-Grasset, Frédéric; Bellouard, Yves

    2010-10-11

    The use of low-energy femtosecond laser beam combined with chemical etching has been proven to be an efficient method to fabricate three-dimensional structures in fused silica. For high-volume application, this technology--like other serial processes--suffers from a moderate production rate. Here, we show that femtosecond laser can also be employed to fabricate silica molds and other patterned surfaces, including surfaces with high aspect ratio features (> 10). Through appropriate tailoring of silica's surface property and subsequent creation of, for instance, simple elastomeric molding, new opportunities for the indirect 3D, multi-scale spatial characterization of deep laser-fabricated microstructures come along. We demonstrate that those moldings are characterized by a high fidelity (down to the nanometer scale) to the silica mold. These results further advance the applicability of femtosecond laser processing to glass. PMID:20941083

  11. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis;

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal and...... suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...

  12. Femtosecond laser sintering of copper nanoparticles

    Science.gov (United States)

    Cheng, C. W.; Chen, J. K.

    2016-04-01

    The ultrafast melting of copper nanoparticles (NPs) induced by a femtosecond laser pulse with duration of 100 fs and wavelength of 800 nm is investigated theoretically and experimentally. The Cu pattern fabricated from sintering of a Cu NP-dispersed film by the femtosecond laser at a repetition rate of 80 MHz is experimentally studied. A one-dimensional two-temperature model with temperature-dependent material properties, including the extended Drude model for dynamic optical properties and the thermophysical properties, is employed to simulate the particles ultrafast melting and re-solidification process.

  13. Femtosecond laser's application in the corneal surgery

    OpenAIRE

    Shu-Liang Wang; Zhi-Fang Qiu; Hong-Li Li; Qin Hu

    2015-01-01

    With the rapid development over the past two decades,femtosecond(10-15s)lasers(FS)has become a new application in ophthalmic surgery. As laser power is defined as energy delivered per unit time, decreasing the pulse duration to femtosecond level(100fs)not only increases the power delivered but also decreases the fluence threshold for laser induced optical breakdown. In ablating tissue, FS has an edge over nanosecond lasers as there is minimal collateral damage from shock waves and heat conduc...

  14. Femtosecond laser ablation of dentin

    International Nuclear Information System (INIS)

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm-2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm-2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm-2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the β-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material. (paper)

  15. Femtosecond laser pulse written Volume Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Richter Daniel

    2013-11-01

    Full Text Available Femtosecond laser pulses can be applied for structuring a wide range of ransparent materials. Here we want to show how to use this ability to realize Volume-Bragg-Gratings in various- mainly non-photosensitive - glasses. We will further present the characteristics of the realized gratings and a few elected applications that have been realized.

  16. Fragmentation of CO in Femtosecond Laser Fields

    International Nuclear Information System (INIS)

    Fragmentation of CO in a linearly polarized femtosecond laser field within the intensity order of 1014 W cm−2 at 820nm is investigated experimentally by using velocity mapping technique. According to the observed kinetic energy and angular distributions of different charged fragment ions, fragmentation channels of CO are proposed. The angular distributions provide helpful information for assigning the dissociation channels

  17. Bending diamonds by femtosecond laser ablation

    DEFF Research Database (Denmark)

    Balling, Peter; Esberg, Jakob; Kirsebom, Kim;

    2009-01-01

    We present a new method based on femtosecond laser ablation for the fabrication of statically bent diamond crystals. Using this method, curvature radii of 1 m can easily be achieved, and the curvature obtained is very uniform. Since diamond is extremely tolerant to high radiation doses, partly due...

  18. Microstructuring of electrospun mats employing femtosecond laser

    Directory of Open Access Journals (Sweden)

    Erika Adomavičiūtė

    2015-03-01

    Full Text Available Electrospun mats from nano/micro-fibers with control porosity and pore shape may be ideal candidate for tissue engineering scaffolds. In this study three type of poly(vinyl alcohol (PVA mats of 48-65 µm thickness with different nano/micro-fibers diameters mostly of 100-200 nm were deposited by electrospinning process. Controlled density porosity in the electrospun mats was introduced by Yb:KGW femtosecond laser micromachining system. The influence of electrospun mat micro structure, the distance between the adjacent laser ablation points, the number of femtosecond laser pulses on quality and structure of laser irradiated holes were investigated. It was demonstrated that the quality of irradiated holes depend on structure of electrospun mats (diameter of nano/micro-fibers, thickness of mats and femtosecond laser processing parameters. Varying the distance between points and number of applied femtosecond laser pulses it is possible to fabricate electrospun mats with pores of 22-36 μm diameter.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.10249

  19. Nonlinear Femtosecond Pulse Reshaping in Waveguide Arrays

    OpenAIRE

    Darren D. Hudson; Shish, Kimberlee; Schibli, Thomas R.; Kutz, J. Nathan; Christodoulides, Demetrios N.; Morandotti, Roberto; Cundiff, Steven T.

    2008-01-01

    We observe nonlinear pulse reshaping of femtosecond pulses in a waveguide array due to coupling between waveguides. Amplified pulses from a mode-locked fiber laser are coupled to an AlGaAs core waveguide array structure. The observed power-dependent pulse reshaping agrees with theory, including shortening of the pulse in the central waveguide.

  20. Femtosecond Generation of Nano-Fibers

    Directory of Open Access Journals (Sweden)

    Richardson Martin

    2013-11-01

    Full Text Available A new approach to making extremely large aspect ratio glass nano-fibers with diameters typically 20 – 40 nm is described. The fabrication process utilizes a novel phenomenon occurring with the interaction of focused high power femtosecond laser radiation with transparent media.

  1. Femtosecond Optical Trapping of Cells: Efficiency and Viability

    Institute of Scientific and Technical Information of China (English)

    GONG Jixian; LI Fang; XING Qirong

    2009-01-01

    The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied. The maximum lateral velocity at which the particles just failed to be trapped, together with the measured average trapping power, were used to calculate the lateral trapping force(Q-value). The viability of the cells after femtosecond laser trapping was ascertained by vital staining. Measurement of the Q-values shows that femtosecond optical tweezers are just as effective as continuous wave optical tweezers. The experiments demonstrate that there is a critical limit for expo-sure time at each corresponding laser power of femtosecond optical tweezers, and femtosecond laser tweezers are safe for optical trapping at low power with short exposure time.

  2. Synthesis of nanocrystalline cubic zirconia using femtosecond laser ablation

    International Nuclear Information System (INIS)

    We report on the synthesis of nanocrystalline zirconia in liquid using femtosecond laser ablation. Nanocrystalline cubic zirconia has been prepared by femtosecond laser ablation of zirconium in ammonia, while nanocrystalline tetragonal and monoclinic zirconia was synthesized in water. The physical and chemical mechanisms of the formation of nanocrystalline metastable zirconia are discussed. The intrinsic properties of femtosecond laser ablation in liquid and OH−1 may be responsible for the synthesis of cubic zirconia. It is suggested that the femtosecond laser pulse can create higher temperature and pressure conditions at a localized area in the liquid than the nanosecond laser pulse and the cooling is also faster in the femtosecond laser ablation process, which determined the difference between the products synthesized with femtosecond and nanosecond-pulsed laser ablation.

  3. Fabrication of Micro -Optical Devices by a Femtosecond Laser

    Institute of Scientific and Technical Information of China (English)

    Kazuyuki; Hirao

    2003-01-01

    Femtosecond laser is a perfect laser source for materials processing when high accuracy and small structure size are required. Due to the ultra short interaction time and the high peak power, the process is generally characterized by the absence of heat diffusion and, consequently molten layers. Various induced structures have been observed in materials after the femtosecond laser irradiation. Here, we report on fabrication of micro-optical devices by the femtosecond laser. 1) formation of optical waveg...

  4. Micromachining soda-lime glass by femtosecond laser pulses

    Science.gov (United States)

    Jia, Wei; Yu, Jian; Chai, Lu; Wang, Ching-Yue

    2015-08-01

    The physical process of forming a modified region in soda-lime glass was investigated using 1 kHz intense femtosecond laser pulses from a Ti: sapphire laser at 775 nm. Through the modifications induced by the femtosecond laser radiation using selective chemical etching techniques, we fabricated reproducible and defined microstructures and further studied their morphologies and etching properties. Moreover, a possible physical mechanism for the femtosecond laser modification in soda-lime glass was proposed.

  5. Micromachining with femtosecond laser written radial polarization converter

    OpenAIRE

    Beresna, M.; Gecevičius, M.; Kazansky, P. G.; Bellouard, Y.; Champion, A.

    2012-01-01

    Structures for microfluidics are fabricated with radially polarized femtosecond laser beam. Radial polarization is produced using birefringent optical element. Omnidirectional etching can be achieved using cylindrically symmetric polarization.

  6. Femtosecond laser machining of electrospun membranes

    Science.gov (United States)

    Wu, Yiquan; Vorobyev, A. Y.; Clark, Robert L.; Guo, Chunlei

    2011-01-01

    We demonstrate that a femtosecond laser can be used to machine arbitrary patterns and pattern arrays into free-standing electrospun polycaprolactone (PCL) membranes. We also examine the influence of various laser irradiation settings on the final microstructure of electrospun membranes. A beam fluence of 0.6 J/cm2 is used to ablate holes in 100 μm thick PCL membranes. The machined holes have an average diameter of 436 μm and a center-to-center spacing of 1000 μm. Based on these results, the femtosecond ablation of electrospun membranes shows great potential for fabricating a variety of functional tissue scaffolds. This technique will advance scaffold design by providing the ability to rapidly tailor surface morphology, while minimizing and controlling the deformation of the electrospun fibers.

  7. Femtosecond laser machining of electrospun membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yiquan, E-mail: wuyiquan@me.rochester.edu [Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627 (United States); Vorobyev, A.Y. [Institute of Optics, University of Rochester, Rochester, NY 14627 (United States); Clark, Robert L. [Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627 (United States); Guo Chunlei [Institute of Optics, University of Rochester, Rochester, NY 14627 (United States)

    2011-01-15

    We demonstrate that a femtosecond laser can be used to machine arbitrary patterns and pattern arrays into free-standing electrospun polycaprolactone (PCL) membranes. We also examine the influence of various laser irradiation settings on the final microstructure of electrospun membranes. A beam fluence of 0.6 J/cm{sup 2} is used to ablate holes in 100 {mu}m thick PCL membranes. The machined holes have an average diameter of 436 {mu}m and a center-to-center spacing of 1000 {mu}m. Based on these results, the femtosecond ablation of electrospun membranes shows great potential for fabricating a variety of functional tissue scaffolds. This technique will advance scaffold design by providing the ability to rapidly tailor surface morphology, while minimizing and controlling the deformation of the electrospun fibers.

  8. Welding of transparent polymers using femtosecond laser

    Science.gov (United States)

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

    2016-02-01

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

  9. Titanium alloy nanosecond vs. femtosecond laser marking

    International Nuclear Information System (INIS)

    Highlights: ► We analyze nanosecond (commercial) and femtosecond laser marks, using SEM and EDAX. ► Elevated repetitive thermal gradients leads to structural defects for double crosses. ► Femtolaser engraving forms amorphous structures, composed of spherical particles. ► We conduct X-ray diffractometry to detect internal micro and residual stresses. ► No internal stresses modification occurred for nano and femtosecond laser marking. - Abstract: There are few papers which aim to analyze the effects of laser marking for traceability on various materials; therefore, the present paper proposes a study of the influences of such radiation processing on a titanium alloy, a vastly used material base within several industry fields. For the novelty impact, femtolaser marking has been carried out, besides the commercial nanosecond standard engraving. All marks have been analyzed using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffractometry.

  10. Femtosecond electron microscopy using photocathode RF gun

    International Nuclear Information System (INIS)

    The revealing and understanding of ultrafast structural-change induced dynamics are essential not only in physics, chemistry and biology, but also are indispensable for the development of new materials, new devices and applications. Both new RF gun based ultrafast relativistic electron diffraction and microscopy (UED and UEM) have being developed in Osaka University to probe directly structural changes at the atomic scale with sub-100 fs temporal resolution in materials. The first prototype of relativistic-energy UEM using a femtosecond photocathode RF gun has been developed. Both ultrafast diffraction and image measurements have been succeeded using a femtosecond electron beam. In this paper, the development of the UEM prototype and the first experiments of relativistic-energy electron imaging will be reported. (author)

  11. Femtosecond dynamics of molecules and clusters

    OpenAIRE

    Baumert, Thomas,; Thalweiser, Rainer; Weiss, V.; Wiedenmann, Ernst; Gerber, Gustav

    1994-01-01

    The real-time dynamics of multiphoton ionization and fragmentation of molecules - Na_2 , Na_3 - and clusters - Na_n, Hg_n - has been studied in molecular beam experiments employing ion and electron spectroscopy together with femtosecond pump-probe techniques. Experiments with Na_2 and Na_3 reveal unexpected features of the dynamics of the absorption of several photons as seen in the one- and three dimensional vibrational wave packet motion in different potential surfaces and...

  12. Encoding and decoding of femtosecond pulses.

    Science.gov (United States)

    Weiner, A M; Heritage, J P; Salehi, J A

    1988-04-01

    We demonstrate the spreading of femtosecond optical pulses into picosecond-duration pseudonoise bursts. Spreading is accomplished by encoding pseudorandom binary phase codes onto the optical frequency spectrum. Subsequent decoding of the spectral phases restores the original pulse. We propose that frequency-domain encoding and decoding of coherent ultrashort pulses could form the basis for a rapidly reconfigurable, code-division multiple-access optical telecommunications network. PMID:19745879

  13. Femtosecond Photodissociation of Molecules Facilitated by Noise

    OpenAIRE

    Singh, Kamal P.; Kenfack, Anatole; Rost, Jan M

    2007-01-01

    We investigate the dynamics of diatomic molecules subjected to both a femtosecond mid-infrared laser pulse and Gaussian white noise. The stochastic Schr\\"odinger equation with a Morse potential is used to describe the molecular vibrations under noise and the laser pulse. For weak laser intensity, well below the dissociation threshold, it is shown that one can find an optimum amount of noise that leads to a dramatic enhancement of the dissociation probability. The enhancement landscape which i...

  14. Femtosecond protein nanocrystallography—data analysis methods

    OpenAIRE

    Kirian, R. A.; X. Wang; Weierstall, U.; Schmidt, K. E.; Spence, J. C. H.; Hunter, M; Fromme, P.; White, Thomas; Chapman, H. N.; Holton, J

    2010-01-01

    X-ray diffraction patterns may be obtained from individual submicron protein nanocrystals using a femtosecond pulse from a free-electron X-ray laser. Many “single-shot” patterns are read out every second from a stream of nanocrystals lying in random orientations. The short pulse terminates before significant atomic (or electronic) motion commences, minimizing radiation damage. Simulated patterns for Photosystem I nanocrystals are used to develop a method for recovering structure factors from ...

  15. Lipidic phase membrane protein serial femtosecond crystallography

    OpenAIRE

    Johansson, LC; Arnlund, D.; White, TA; Katona, G.; DePonte, DP; Weierstall, U.; Doak, RB; Shoeman, RL; Lomb, L; Malmerberg, E.; Davidsson, J; Nass, K.; Liang, MN; Andreasson, J.; Dell'Aquila, A.

    2012-01-01

    X-ray free electron laser (X-FEL)-based serial femtosecond crystallography is an emerging method with potential to rapidly advance the challenging field of membrane protein structural biology. Here we recorded interpretable diffraction data from micrometer-sized lipidic sponge phase crystals of the Blastochloris viridis photosynthetic reaction center delivered into an X-FEL beam using a sponge phase micro-jet.

  16. Remotely manageable system for stabilizing femtosecond lasers

    Czech Academy of Sciences Publication Activity Database

    Čížek, Martin; Hucl, Václav; Šmíd, Radek; Mikel, Břetislav; Lazar, Josef; Číp, Ondřej

    Bellingham: SPIE, 2014, 913527:1-6. ISBN 9781628410839. ISSN 0277-786X. [Laser Sources and Applications /2./. Brussels (BE), 14.04.2014-17.04.2014] R&D Projects: GA ČR GAP102/10/1813; GA MŠk ED3.1.00/12.0232; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : femtosecond lasers * lasers * signal processing * frequency combs * laser spectroscopy * clocks * digital signal processing Subject RIV: BH - Optics, Masers, Lasers

  17. Beam Characterizations at Femtosecond Electron Beam Facility

    CERN Document Server

    Rimjaem, Sakhorn; Kangrang, Nopadol; Kusoljariyakul, Keerati; Rhodes, Michael W; Saisut, Jatuporn; Thongbai, Chitrlada; Vilaithong, Thiraphat; Wichaisirimongkol, Pathom; Wiedemann, Helmut

    2005-01-01

    The SURIYA project at the Fast Neutron Research Facility (FNRF) has been established and is being commissioning to generate femtosecond electron pulses. Theses short pulses are produced by a system consisting of an S-band thermionic cathode RF-gun, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The characteristics of its major components and the beam characterizations as well as the preliminary experimental results will be presented and discussed.

  18. Femtosecond Laser Induced Underwater Superoleophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Yong Jiale

    2015-01-01

    Full Text Available Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. Silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to the fish’s scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° for the 1,2-dichloroethane droplets in water. Besides, the surface exhibits ultralow oil-adhesion. In the oil/water/solid three-phase system, water can be trapped in the hierarchical rough structure and forms a repulsive oil layer according to underwater Cassie’s theory. The contact area between the asprepared surface and oil droplet is significantly reduced, resulting in superoleophobicity and ultralow oil-adhesion in water. In addition, transparent underwater superoleophobic and anti-oil surfaces are achieved on silica glass surfaces by femtosecond laser ablation. This transparent property is attributed to the presence of the water environment because scattering and refraction are effectively weakened. The presented method is simple and can accurately control the processing location, which may have widely potential applications in, for instance, microfluidics, biotechnologies, and antifouling coatings.

  19. Characterizing THz Coherent Synchrotron Radiation at Femtosecond Linear Accelerator

    Institute of Scientific and Technical Information of China (English)

    LIN Xu-Ling; ZHANG Jian-Bing; LU YU; LUO Feng; LU Shan-Liang; YU Tie-Min; DAI Zhi-Min

    2009-01-01

    The generation and observation of coherent THz synchrotron radiation from femtosecond electron bunches in the Shanghai Institute of Applied Physics femtosecond accelerator device is reported.We describe the experiment setup and present the first result of THz radiation properties such as power and spectrum.

  20. Parallel femtosecond laser processing with vector-wave control

    Directory of Open Access Journals (Sweden)

    Hayasaki Yoshio

    2013-11-01

    Full Text Available Parallel femtosecond laser processing with a computer-generated hologram displayed on a spatial light modulator, has the advantages of high throughput and high energy-use efficiency. for further increase of the processing efficiency, we demonstrated parallel femtosecond laser processing with vector-wave control that is based on polarization control using a pair of spatial light modulators.

  1. Fabrication of Micro -Optical Devices by a Femtosecond Laser

    Institute of Scientific and Technical Information of China (English)

    Jianrong Qiu; Kazuyuki Hirao

    2003-01-01

    Femtosecond laser is a perfect laser source for materials processing when high accuracy and small structure size are required. Due to the ultra short interaction time and the high peak power, the process is generally characterized by the absence of heat diffusion and, consequently molten layers. Various induced structures have been observed in materials after the femtosecond laser irradiation. Here, we report on fabrication of micro-optical devices by the femtosecond laser. 1) formation of optical waveguide with internal loss less than 0.5dB/cm in the wavelength region from 1.2 to 1.6 mm, by translating a silica glass perpendicular to the axis of the focused femtosecond laser beam; 2) nano-scale valence state manipulation of active ions inside transparent materials; 3) space-selective precipitation and control of metal nanoparticles inside transparent materials; The mechanisms and applications of the femtosecond laser induced phenomena were also discussed.

  2. Femtosecond laser induced breakdown for combustion diagnostics

    International Nuclear Information System (INIS)

    The focused beam of a 100 fs, 800 nm laser is used to induce a spark in some laminar premixed air-methane flames operating with variable fuel content (equivalence ratio). The analysis of the light escaping from the plasma revealed that the Balmer hydrogen lines, Hα and Hβ, and some molecular origin emissions were the most prominent spectral features, while the CN (Β2Σ+-Χ2Σ+) band intensity was found to depend linearly with methane content, suggesting that femtosecond laser induced breakdown spectroscopy can be a useful tool for the in-situ determination and local mapping of fuel content in hydrocarbon-air combustible mixtures.

  3. Femtosecond laser in refractive and cataract surgeries

    Institute of Scientific and Technical Information of China (English)

    Han-Han; Liu; Ying; Hu; Hong-Ping; Cui

    2015-01-01

    In the past few years, 9 unique laser platforms have been brought to the market. As femtosecond(FS) laserassisted ophthalmic surgery potentially improves patient safety and visual outcomes, this new technology indeed provides ophthalmologists a reliable new option. But this new technology also poses a range of new clinical and financial challenges for surgeons. We provide an overview of the evolution of FS laser technology for use in refractive and cataract surgeries. This review describes the available laser platforms and mainly focuses on discussing the development of ophthalmic surgery technologies.

  4. Femtosecond laser in gauge block calibration

    Czech Academy of Sciences Publication Activity Database

    Buchta, Zdeněk; Čížek, Martin; Hucl, Václav; Řeřucha, Šimon; Šarbort, Martin; Lazar, Josef; Číp, Ondřej

    Montenegro : University of Montenegro, 2013. [ALT´13. Annual International Conference on Advanced Laser Technologies /21./. Budva (ME), 16.09.2013-20.09.2013] R&D Projects: GA ČR GP102/09/P293; GA ČR GPP102/11/P819; GA ČR GAP102/10/1813; GA MPO FR-TI2/705; GA TA ČR(CZ) TA03010663; GA MŠk ED0017/01/01; GA MŠk(CZ) LC06007 Institutional support: RVO:68081731 Keywords : Femtosecond laser * calibration cell Subject RIV: BH - Optics, Masers, Lasers

  5. Femtosecond laser in gauge block calibration

    Czech Academy of Sciences Publication Activity Database

    Buchta, Zdeněk; Čížek, Martin; Hucl, Václav; Řeřucha, Šimon; Šarbort, Martin; Lazar, Josef; Číp, Ondřej

    Montenegro : University of Montenegro, 2013. [ALT´13. Annual International Conference on Advanced Laser Technologies /21./. 16.09.2013-20.09.2013, Budva] R&D Projects: GA ČR GP102/09/P293; GA ČR GPP102/11/P819; GA ČR GAP102/10/1813; GA MPO FR-TI2/705; GA TA ČR(CZ) TA03010663; GA MŠk ED0017/01/01; GA MŠk(CZ) LC06007 Institutional support: RVO:68081731 Keywords : Femtosecond laser * calibration cell Subject RIV: BH - Optics, Masers, Lasers

  6. Berkeley Lab's ALS generates femtosecond synchrotron radiation

    International Nuclear Information System (INIS)

    A Lawrence Berkeley National Laboratory team has succeeded in generating 300 fs pulses of synchrotron radiation at the ALS synchrotron radiation machine. Although this proof-of-principle experiment made use of visible light on a borrowed beamline, the laser 'time-slicing' technique at the heart of the demonstration will soon be applied in a new bend-magnet beamline that was designed specially for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness

  7. Creation of optical vortices in femtosecond pulses.

    Science.gov (United States)

    Mariyenko, I; Strohaber, J; Uiterwaal, Cornelis

    2005-09-19

    We experimentally created a femtosecond optical vortex using a pair of computer-synthesized holographic gratings arranged in a 2f - 2f optical setup. We present measurements showing that the resulting donut mode is free of spatial chirp, and support this finding with an analysis of the optical wave propagation through our system based on the Kirchhoff-Fresnel diffraction integral. An interferogram confirms that our ultrashort vortex has topological charge 1, and a conservative experimental estimation of its duration is 280 fs. We used 25-fs radiation pulses (bandwidth approximately 40 nm) produced by a Ti:sapphire laser oscillator. PMID:19498786

  8. Femtosecond laser studies of ultrafast intramolecular processes

    Energy Technology Data Exchange (ETDEWEB)

    Hayden, C. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this research is to better understand the detailed mechanisms of chemical reactions by observing, directly in time, the dynamics of fundamental chemical processes. In this work femtosecond laser pulses are used to initiate chemical processes and follow the progress of these processes in time. The authors are currently studying ultrafast internal conversion and subsequent intramolecular relaxation in unsaturated hydrocarbons. In addition, the authors are developing nonlinear optical techniques to prepare and monitor the time evolution of specific vibrational motions in ground electronic state molecules.

  9. Production of high power femtosecond terahertz radiation

    Science.gov (United States)

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

    2003-07-01

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

  10. Dual echelon femtosecond single-shot spectroscopy

    International Nuclear Information System (INIS)

    We have developed a femtosecond single-shot spectroscopic technique to measure irreversible changes in condensed phase materials in real time. Crossed echelons generate a two-dimensional array of time-delayed pulses with one femtosecond probe pulse. This yields 9 ps of time-resolved data from a single laser shot, filling a gap in currently employed measurement methods. We can now monitor ultrafast irreversible dynamics in solid-state materials or other samples that cannot be flowed or replenished between laser shots, circumventing limitations of conventional pump-probe methods due to sample damage or product buildup. Despite the absence of signal-averaging in the single-shot measurement, an acceptable signal-to-noise level has been achieved via background and reference calibration procedures. Pump-induced changes in relative reflectivity as small as 0.2%−0.5% are demonstrated in semimetals, with both electronic and coherent phonon dynamics revealed by the data. The optical arrangement and the space-to-time conversion and calibration procedures necessary to achieve this level of operation are described. Sources of noise and approaches for dealing with them are discussed

  11. Optical gene transfer by femtosecond laser pulses

    Science.gov (United States)

    Konig, Karsten; Riemann, Iris; Tirlapur, Uday K.

    2003-07-01

    Targeted transfection of cells is an important technique for gene therapy and related biomedical applications. We delineate how high-intensity (1012 W/cm2) near-infrared (NIR) 80 MHz nanojoule femtosecond laser pulses can create highly localised membrane perforations within a minute focal volume, enabling non-invasive direct transfection of mammalian cells with DNA. We suspended Chinese hamster ovarian (CHO), rat kangaroo kidney epithelial (PtK2) and rat fibroblast cells in 0.5 ml culture medium in a sterile miniaturized cell chamber (JenLab GmbH, Jena, Germany) containing 0.2 μg plasmid DNA vector pEGFP-N1 (4.7 kb), which codes for green fluorescent protein (GFP). The NIR laser beam was introduced into a femtosecond laser scanning microscope (JenLab GmbH, Jena, Germany; focussed on the edge of the cell membrane of a target cell for 16 ms. The integration and expression efficiency of EGFP were assessed in situ by two-photon fluorescence-lifetime imaging using time-correlated single photon counting. The unique capability to transfer foreign DNA safely and efficiently into specific cell types (including stem cells), circumventing mechanical, electrical or chemical means, will have many applications, such as targeted gene therapy and DNA vaccination.

  12. Micromachining of copper by femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.Y. [ITRI South, Industrial Technology Research Institute, Liujia District, Tainan City 734, Taiwan (China); Ren, Y. [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211 (United States); Cheng, C.W., E-mail: CWCheng@itri.org.tw [ITRI South, Industrial Technology Research Institute, Liujia District, Tainan City 734, Taiwan (China); Chen, J.K.; Tzou, D.Y. [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211 (United States)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer We have reported new experimental and theoretical results on the femtosecond laser ablation for copper at fluences up to 408 J/cm{sup 2}. Black-Right-Pointing-Pointer The present model simulations correlate well with the experimental data over a broad range of laser fluences from 0.8 to 400 J/cm{sup 2}. Black-Right-Pointing-Pointer The good correlation suggests that the proposed model is an efficient and accurate tool for predicting ultrafast laser material ablation. - Abstract: Simulation results of femtosecond laser ablation of copper were compared to experimental data. The numerical analysis was performed using a predictive model, including a two temperature model, an optical critical point model with three Lorentzian terms, two phase change models for melting and evaporation under superheating, and a phase explosion criterion for ejection of metastable liquid decomposing into droplets and vapor phase. The experiments were conducted with a 120-fs, 800-nm Ti:sapphire lasers for fluences up to 408 J/cm{sup 2}. The ablation depths were measured, and the ablation rate was estimated. It was shown that the present numerical simulations correlate well with the experimental data over the entire range of the laser fluences investigated except for those below 0.8 J/cm{sup 2}, indicating that the proposed model is an accurate and efficient tool for predicting ultrashort-pulsed laser material ablation.

  13. Pico-femtosecond image-tube photography in quantum electronics

    International Nuclear Information System (INIS)

    The possibility of experimental achievement of the time resolution of image-converter tubes (ICTs) corresponding to the theoretical limit of 10 fs is considered as applied to quantum electronics problems. A new generation of ICTs with a temporal resolution of 200 - 500 fs has been developed for recording femtosecond laser radiation. The entirely new devices based on time-analysing ICTs such as femtosecond photoelectronic diffractometers, have been created for studying the dynamics of phase transitions in substances using diffrac-tion of electrons with energies ranging from 20 to 40 keV. (femtosecond technologies)

  14. Femtosecond laser cataract surgery: technology and clinical practice.

    Science.gov (United States)

    Roberts, Timothy V; Lawless, Michael; Chan, Colin Ck; Jacobs, Mark; Ng, David; Bali, Shveta J; Hodge, Chris; Sutton, Gerard

    2013-03-01

    The recent introduction of femtosecond lasers to cataract surgery has generated much interest among ophthalmologists around the world. Laser cataract surgery integrates high-resolution anterior segment imaging systems with a femtosecond laser, allowing key steps of the procedure, including the primary and side-port corneal incisions, the anterior capsulotomy and fragmentation of the lens nucleus, to be performed with computer-guided laser precision. There is emerging evidence of reduced phacoemulsification time, better wound architecture and a more stable refractive result with femtosecond cataract surgery, as well as reports documenting an initial learning curve. This article will review the current state of technology and discuss our clinical experience. PMID:22788831

  15. Femtosecond laser 3D micromachining for microfluidic and optofluidic applications

    CERN Document Server

    Sugioka, Koji

    2013-01-01

    Femtosecond lasers opened up new avenue in materials processing due to its unique features of ultrashort pulse width and extremely high peak intensity. One of the most important features of femtosecond laser processing is that strong absorption can be induced even by materials which are transparent to the femtosecond laser beam due to nonlinear multiphoton absorption. The multiphoton absorption allows us to perform not only surface but also three-dimensionally internal microfabrication of transparent materials such as glass. This capability makes it possible to directly fabricate three-dimensi

  16. Femtosecond Scanning, Chopping (Slicing) and Measurement of Length of Electron Bunches by Laser Pulses: Principles of Femtosecond Oscilloscopes

    International Nuclear Information System (INIS)

    The equations of motion of electrons in a plane monochromatic wave with linear, circular and elliptical polarizations are solved taking into account the initial conditions. The cases when the interaction of the electrons with field of linear and circularly polarized laser photon beams takes place during a finite time, while the electrons are detected after a long field-free region being scanned with period of the order of femtosecond, are suitable for femto slicing and measurement of length of femtosecond electron pulses. The principles and limitations of slicing and of construction of laser femtosecond oscilloscopes are considered, and a scheme of experiment is proposed

  17. Monitor and control of neuronal activities with femtosecond pulse laser

    Institute of Scientific and Technical Information of China (English)

    ZHOU Wei; LIU XiuLi; L(U) XiaoHua; LI JiaSong; LUO QingMing; ZENG ShaoQun

    2008-01-01

    Combined with the fluorescence labeling technique, two-photon microscopy excited with femtosecond pulse laser has become an important tool for neuroscience research. In this research, the calcium signals from neurons in rat cortex slice were monitored by a custom-built two-photon microscopy, and the spontaneous calcium signals and the pharmacological responses as well as the responses to femtosecond pulse laser stimulation were recorded. The results showed that the amplitude of the cal-cium signals increased in direct proportion to the corresponding electrical activities. Glutamate induced a calcium transient, but continuous application resulted in smaller response. Simultaneous monitoring of neuronal populations distinguished the neurons of different microcircuits. The femtosecond pulse laser induced local or global calcium signals in the pyramidal neurons. The approach of interrogation and control of neural activities using femtosecond pulse laser is non-contact, nondestructive, repeatable, and without any additional substrates, which will contribute to the development of neuroscience.

  18. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

    Tan, D.Z.; Sharafudeen, K.N.; Yue, Yuanzheng;

    2016-01-01

    the art in studying femtosecond laser induced various phenomena in transparent materials, including their physical and chemical mechanisms, the applications and limitations as well as the future research trends. The first part of the review presents the basics of femtosecond laser systems, important......The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been...... solved, especially concerning the interaction of strong, ultra-short electromagnetic pulses with matter, and also because potential advanced technologies will emerge due to the impressive capability of the intense femtosecond laser to create new material structures and hence functionalities. When...

  19. Diamond photonics platform enabled by femtosecond laser writing

    OpenAIRE

    Sotillo, Belen; Bharadwaj, Vibhav; Hadden, J. P.; Sakakura, Masaaki; Chiappini, Andrea; Fernandez, Toney Teddy; Longhi, Stefano; Jedrkiewicz, Ottavia; Shimotsuma, Yasuhiko; Criante, Luigino; Osellame, Roberto; Galzerano, Gianluca; Ferrari, Maurizio; Miura, Kiyotaka; Ramponi, Roberta

    2016-01-01

    We demonstrate the first buried optical waveguides in diamond using focused femtosecond laser pulses. The properties of nitrogen vacancy centers are preserved in the waveguides, making them promising for diamond-based magnetometers or quantum information systems.

  20. New science and art of femtosecond laser writing

    OpenAIRE

    Kazansky, Peter G.

    2009-01-01

    Common beliefs that laser writing does not change when reversing beam scan or propagation direction are challenged. Recently discovered phenomena of quill and non-reciprocal femtosecond laser writing in glasses and crystals are reviewed.

  1. Femtosecond laser embedded grating micromachining of flexible PDMS plates

    Science.gov (United States)

    Cho, Sung-Hak; Chang, Won-Seok; Kim, Kwang-Ryul; Hong, Jong Wook

    2009-04-01

    We report on the femtosecond laser micromachining of photo-induced embedded diffraction grating in flexible Poly (Dimethly Siloxane) (PDMS) plates using a high-intensity femtosecond (130 fs) Ti: sapphire laser ( λp = 800 nm). The refractive index modifications with diameters ranging from 2 μm to 5 μm were photo-induced after the irradiation with peak intensities of more than 1 × 10 11 W/cm 2. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which femtosecond laser was focused. The maximum refractive index change (Δ n) was estimated to be 2 × 10 -3. By the X- Y- Z scanning of sample, the embedded diffraction grating in PDMS plate was fabricated successfully using a femtosecond laser.

  2. Polarization diffraction grating produced by femtosecond laser nanostructuring in glass

    OpenAIRE

    Beresna, M.; Kazansky, P.G.

    2010-01-01

    We demonstrate polarization sensitive diffractive optical element fabrication by femtosecond direct writing in the bulk of silica glass. Modulation of the anisotropic properties is produced by controlling light-induced self-assembled nano-gratings.

  3. Femtosecond soliton diode on heterojunction Bragg-grating structure

    CERN Document Server

    Deng, Zhigui; Li, Hongji; Fu, Shenhe; Liu, Yikun; Xiang, Ying; Li, Yongyao

    2016-01-01

    We numerically propose a scheme for realizing an all-optical femtosecond soliton diode based on a tailored heterojunction Bragg grating, which is designed by two spatially asymmetric chirped cholesteric liquid crystals. Our simulations demonstrate that with the consideration of optical nonlinearity, not only the femtosecond diode effect with nonreciprocal transmission ratio up to 120 can be achieved, but also the optical pulse evolving into soliton which maintains its shape during propagation through the sample is observed. Further, the influence of pulse width and the carrier wavelength to the femtosecond diode effect is also discussed in detail. Our demonstrations might suggest a new direction for experimentally realizing the femtosecond soliton diode based on the cholesteric liquid crystals.

  4. Noncontact microsurgery of living cell membrane using femtosecond laser pulses

    Science.gov (United States)

    Ilina, I. V.; Ovchinnikov, A. V.; Sitnikov, D. S.; Chefonov, O. V.; Agranat, M. B.; Mikaelyan, A. S.

    2013-06-01

    Near-infrared femtosecond laser pulses were applied to initiate reversible permeabilization of cell membrane and inject extrinsic substances into the target cells. Successful laser-based injection of a membrane impermeable dye, as well as plasmid DNA was demonstrated.

  5. Towards a compact thin-disk-based femtosecond XUV source

    OpenAIRE

    Pronin, Oleg

    2012-01-01

    The goal of this thesis is to develop a compact high-power solid-state oscillator capable of superseding existing ultrafast technology based on low-power Ti:sapphire oscillators. Different applications such as extra- or intra-cavity XUV generation, seeding of high-energy low-repetition-rate amplifier systems and femtosecond enhancement cavities can be dramatically influenced by the availability of such a reliable, compact femtosecond source. We applied, for the first time, Kerr-lens mode-...

  6. Femtosecond Laser Fabrication of Monolithically Integrated Microfluidic Sensors in Glass

    OpenAIRE

    Fei He; Yang Liao; Jintian Lin; Jiangxin Song; Lingling Qiao; Ya Cheng; Koji Sugioka

    2014-01-01

    Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D) structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applicatio...

  7. Materials processing with a tightly focused femtosecond vortex laser pulse

    OpenAIRE

    Hnatovsky, Cyril; Shvedov, Vladlen G.; Krolikowski, Wieslaw; Rode, Andrei V.

    2010-01-01

    This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than...

  8. Materials processing with tightly focused femtosecond vortex laser beams

    OpenAIRE

    Hnatovsky, Cyril; Shvedov, Vladlen G.; Krolikowski, Wieslaw; Rode, Andrei V.

    2010-01-01

    This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than...

  9. Femtosecond laser processing of photovoltaic and transparent materials

    OpenAIRE

    Sanghoon AHN

    2013-01-01

    The photovoltaic semiconducting and transparent dielectric materials are of high interest in current industry. Femtosecond laser processing can be an effective technique to fabricate such materials since non-linear photochemical mechanisms predominantly occur. In this series of studies, femtosecond (fs) laser processing techniques that include laser drilling on Si wafer, laser scribing on CIGS thin film, laser ablation on Lithium Niobate (LN) crystal, and fabrication of 3D structures in fused...

  10. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  11. Optical data storage in nonphotosensitive media by femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ultrashort lasers have become powerful tools by inducing extremely nonlinear effects in a wide variety of materials.Femtosecond laser data storage in non-photosensitive media is promising for its high density and fast retrieval. We reviewed the progress of three types of femtosecond laser storage in transparent materials: three-dimensional bit-oriented storage by micro-voids, holographic data storage by two beam interference and storage by computer-generated holograms.

  12. Nanodot formation induced by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    The femtosecond laser generation of ZnSe nanoscale features on ZnSe surfaces was studied. Irradiation with multiple exposures produces 10–100 nm agglomerations of nanocrystalline ZnSe while retaining the original single crystal structure of the underlying material. The structure of these nanodots was verified using a combination of scanning transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The nanodots continue to grow hours after irradiation through a combination of bulk and surface diffusion. We suggest that in nanodot formation the result of ultrafast laser induced point defect formation is more than an order of magnitude below the ZnSe ultrafast melt threshold fluence. This unique mechanism of point defect injection will be discussed.

  13. Thin Film Femtosecond Laser Damage Competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Ristau, D; Turowski, M; Blaschke, H

    2009-11-14

    In order to determine the current status of thin film laser resistance within the private, academic, and government sectors, a damage competition was started at the 2008 Boulder Damage Symposium. This damage competition allows a direct comparison of the current state of the art of high laser resistance coatings since they are tested using the same damage test setup and the same protocol. In 2009 a high reflector coating was selected at a wavelength of 786 nm at normal incidence at a pulse length of 180 femtoseconds. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials and layer count, and spectral results will also be shared.

  14. Femtosecond fiber laser welding of dissimilar metals.

    Science.gov (United States)

    Huang, Huan; Yang, Lih-Mei; Bai, Shuang; Liu, Jian

    2014-10-01

    In this paper, welding of dissimilar metals was demonstrated for the first time, to the best of our knowledge, by using a high-energy high-repetition-rate femtosecond fiber laser. Metallurgical and mechanical properties were investigated and analyzed under various processing parameters (pulse energy, repetition rate, and welding speed). Results showed that the formation of intermetallic brittle phases and welding defects could be effectively reduced. Strong welding quality with more than 210 MPa tensile strength for stainless steel-aluminum and 175 MPa tensile strength for stainless steel-magnesium has been demonstrated. A minimal heat affected zone and uniform and homogenous phase transformation in the welding region have been demonstrated. This laser-welding technique can be extended for various applications in semiconductor, automobile, aerospace, and biomedical industries. PMID:25322246

  15. Femtosecond laser enabled keratoplasty for advanced keratoconus

    Directory of Open Access Journals (Sweden)

    Yathish Shivanna

    2013-01-01

    Full Text Available Purpose : To assess the efficacy and advantages of femtosecond laser enabled keratoplasty (FLEK over conventional penetrating keratoplasty (PKP in advanced keratoconus. Materials and Methods: Detailed review of literature of published randomized controlled trials of operative techniques in PKP and FLEK. Results: Fifteen studies were identified, analyzed, and compared with our outcome. FLEK was found to have better outcome in view of better and earlier stabilization uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA, and better refractive outcomes with low astigmatism as compared with conventional PKP. Wound healing also was noticed to be earlier, enabling early suture removal in FLEK. Conclusions: Studies relating to FLEK have shown better results than conventional PKP, however further studies are needed to assess the safety and intraoperative complications of the procedure.

  16. Optical reprogramming with ultrashort femtosecond laser pulses

    Science.gov (United States)

    Uchugonova, Aisada; Breunig, Hans G.; Batista, Ana; König, Karsten

    2015-03-01

    The use of sub-15 femtosecond laser pulses in stem cell research is explored with particular emphasis on the optical reprogramming of somatic cells. The reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be evoked through the ectopic expression of defined transcription factors. Conventional approaches utilize retro/lenti-viruses to deliver genes/transcription factors as well as to facilitate the integration of transcription factors into that of the host genome. However, the use of viruses may result in insertional mutations caused by the random integration of genes and as a result, this may limit the use within clinical applications due to the risk of the formation of cancer. In this study, a new approach is demonstrated in realizing non-viral reprogramming through the use of ultrashort laser pulses, to introduce transcription factors into the cell so as to generate iPS cells.

  17. Femtosecond fiber laser additive manufacturing of tungsten

    Science.gov (United States)

    Bai, Shuang; Liu, Jian; Yang, Pei; Zhai, Meiyu; Huang, Huan; Yang, Lih-Mei

    2016-04-01

    Additive manufacturing (AM) is promising to produce complex shaped components, including metals and alloys, to meet requirements from different industries such as aerospace, defense and biomedicines. Current laser AM uses CW lasers and very few publications have been reported for using pulsed lasers (esp. ultrafast lasers). In this paper, additive manufacturing of Tungsten materials is investigated by using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. Fully dense Tungsten part with refined grain and increased hardness was obtained and compared with parts made with different pulse widths and CW laser. The results are evidenced that the fs laser based AM provides more dimensions to modify mechanical properties with controlled heating, rapid melting and cooling rates compared with a CW or long pulsed laser. This can greatly benefit to the make of complicated structures and materials that could not be achieved before.

  18. Femtosecond laser processing and spatial light modulator

    Science.gov (United States)

    Paivasaari, Kimmo; Silvennoinen, Martti; Kaakkunen, Jarno; Vahimaa, Pasi

    2014-03-01

    The use of the femtosecond laser enables generation of small spot sizes and ablation features. Ablation of the small features usually requires only a small amount of laser power to be delivered to the ablation spot. When using only a one beam for the ablation of the small features this process is bound to be time consuming. The spatial light modulator (SLM) together with the computer generated holograms (CGH) can be used for manipulating and shaping of the laser beam in various applications. In laser micromachining, when using laser with relatively high power, the original beam can be divided up to hundreds beams and still have the energy of the individual beam above the ablation threshold of the material. This parallel laser processing enables more efficient use of the laser power regardless of the machining task.

  19. Femtosecond laser technologies for linear collider designs

    CERN Document Server

    Kobayashi, K

    2001-01-01

    A highly stabilized high-energy femtosecond laser system was developed for Compton X-ray experiments. The laser system is based on the chirped pulse amplification, and each component is actively or passively stabilized. A master oscillator with less than 100 fs timing jitter, two independent oscillators with 300 fs relative timing lag, a new measurement technique of timing fluctuation of low-repetition amplified pulse, and a special designed regenerative amplifier with high quality beam were developed. New technical options for linear collider are proposed based on these expertises. The options are temporally square pulse for low emittance electron generation, a timing stabilized seeder for CO sub 2 amplifier, and multi-pulse high-energy lasers for gamma-gamma collision and for multi-bunch electron generation.

  20. Femtosecond Carrier Dynamics and Modelocking in Monolithic CPM Lasers. [SB1

    DEFF Research Database (Denmark)

    Brorson, S.D.; Bischoff, Svend; MØrk, J.;

    1996-01-01

    Femtosecond pump-probe measurements of the dynamics in both forward- and reverse-biased semiconductor optical waveguides arepresented. Slow (nanosecond) as well as ultrafast (femtosecond) dynamics are observed in both kinds of structures.......Femtosecond pump-probe measurements of the dynamics in both forward- and reverse-biased semiconductor optical waveguides arepresented. Slow (nanosecond) as well as ultrafast (femtosecond) dynamics are observed in both kinds of structures....

  1. Holographic femtosecond laser manipulation for advanced material processing

    Science.gov (United States)

    Hasegawa, Satoshi; Hayasaki, Yoshio

    2016-02-01

    Parallel femtosecond laser processing using a computer-generated hologram displayed on a spatial light modulator, known as holographic femtosecond laser processing, provides the advantages of high throughput and high-energy use efficiency. Therefore, it has been widely used in many applications, including laser material processing, two-photon polymerization, two-photon microscopy, and optical manipulation of biological cells. In this paper, we review the development of holographic femtosecond laser processing over the past few years from the perspective of wavefront and polarization modulation. In particular, line-shaped and vector-wave femtosecond laser processing are addressed. These beam-shaping techniques are useful for performing large-area machining in laser cutting, peeling, and grooving of materials and for high-speed fabrication of the complex nanostructures that are applied to material-surface texturing to control tribological properties, wettability, reflectance, and retardance. Furthermore, issues related to the nonuniformity of diffraction light intensity in optical reconstruction and wavelength dispersion from a computer-generated hologram are addressed. As a result, large-scale holographic femtosecond laser processing over 1000 diffraction spots was successfully demonstrated on a glass sample.

  2. Femtosecond laser fabrication of monolithically integrated microfluidic sensors in glass.

    Science.gov (United States)

    He, Fei; Liao, Yang; Lin, Jintian; Song, Jiangxin; Qiao, Lingling; Cheng, Ya; Sugioka, Koji

    2014-01-01

    Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D) structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applications. These include 3D integration of micro-/nanofluidic, optofluidic, electrofluidic, surface-enhanced Raman-scattering devices, in addition to fabrication of devices for microfluidic bioassays and lab-on-fiber sensors. This paper describes the unique characteristics of femtosecond laser processing and the basic concepts involved in femtosecond laser direct writing. Advanced spatiotemporal beam shaping methods are also discussed. Typical examples of microfluidic sensors fabricated using femtosecond lasers are then highlighted, and their applications in chemical and biological sensing are described. Finally, a summary of the technology is given and the outlook for further developments in this field is considered. PMID:25330047

  3. Femtosecond Laser Fabrication of Monolithically Integrated Microfluidic Sensors in Glass

    Directory of Open Access Journals (Sweden)

    Fei He

    2014-10-01

    Full Text Available Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applications. These include 3D integration of micro-/nanofluidic, optofluidic, electrofluidic, surface-enhanced Raman-scattering devices, in addition to fabrication of devices for microfluidic bioassays and lab-on-fiber sensors. This paper describes the unique characteristics of femtosecond laser processing and the basic concepts involved in femtosecond laser direct writing. Advanced spatiotemporal beam shaping methods are also discussed. Typical examples of microfluidic sensors fabricated using femtosecond lasers are then highlighted, and their applications in chemical and biological sensing are described. Finally, a summary of the technology is given and the outlook for further developments in this field is considered.

  4. Design and analysis of X-band femtosecond linac

    Energy Technology Data Exchange (ETDEWEB)

    Uesaka, M.; Kozawa, T.; Takeshita, A.; Kobayashi, T.; Ueda, T.; Miya, K. [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1997-03-01

    Femtosecond quantum phenomena research project is proposed at Nuclear Engineering Research Laboratory, University of Tokyo. The research facility consists of an X-band (11.424GHz) femtosecond electron linac, a femtosecond wavelength tunable laser, two S-band (2.856GHz) picosecond electron linacs and measuring equipments. Especially, we aim to generate a 100 fs (FWHM) electron single bunch with more than 1 nC at the X-band femtosecond linac. Ultrafast processes in radiation physics, chemistry, material science and microscopic electromagnetic phenomena are going to be analyzed there. Here the design and analysis of an X-band femtosecond linac is presented. The simulation of electron dynamics is carried out including magnetic pulse compression by using PARMELA and SUPERFISH. It is found by the simulation that the 600 ps (tail-to-tail) electron emission from a 200 kV thermionic gun can be bunched and compressed to 110 fs (FWHM) with the charge of 0.8 nC which gives 7.3 kA. We plan to use one high power X-band klystron which can supply 60 MW with more than 200 ns pulse duration. The flatness of plateau of the pulse should be 0.2% for stable ultrashort bunch generation. (author)

  5. Femtosecond X-ray protein nanocrystallography

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Henry N. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Univ. of Hamburg (Germany); Barty, Anton [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; White, Thomas A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Aquila, Andrew [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Schulz, Joachim [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; DePonte, Daniel P. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Martin, Andrew V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Coppola, Nicola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Liang, Mengning [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Caleman, Carl [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Gumprecht, Lars [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Stern, Stephan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science; Nass, Karol [Univ. of Hamburg (Germany); Fromme, Petra [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry and Biochemistry; Hunter, Mark S. [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry and Biochemistry; Grotjohann, Ingo [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry and Biochemistry; Fromme, Raimund [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry and Biochemistry; Kirian, Richard A. [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Weierstall, Uwe [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Doak, R. Bruce [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Schmidt, Kevin E. [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Wang, Xiaoyu [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Spence, John C. H. [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics; Schlichting, Ilme [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Epp, Sascha W. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Rolles, Daniel [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Rudenko, Artem [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Foucar, Lutz [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Rudek, Benedikt [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Erk, Benjamin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Schmidt, Carlo [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Hömke, André [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Strüder, Lothar [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Society Semiconductor Lab., Munich (Germany); Ullrich, Joachim [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Krasniqi, Faton [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science, Max Planck Advanced Study Group; Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Lomb, Lukas [Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Shoeman, Robert L. [Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Bott, Mario [Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Barends, Thomas R. M. [Max Planck Inst. fur Medizinische Forschung, Heidelberg (Germany); Kuhnel, Kai-Uwe [Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Schroter, Claus-Dieter [Max Planck Inst. fur Kernphysik, Heidelberg (Germany); Hartmann, Robert [PNSensor GmbH, Munich (Germany); Holl, Peter [PNSensor GmbH, Munich (Germany); Reich, Christian [PNSensor GmbH, Munich (Germany); Soltau, Heike [PNSensor GmbH, Munich (Germany); Kimmel, Nils [Max Planck Society Semiconductor Lab., Munich (Germany); Weidenspointner, Georg [Max Planck Society Semiconductor Lab., Munich (Germany); Max Planck Inst. fur Extraterrestrische Physik, Garching (Germany); Pietschner, Daniel [Max Planck Society Semiconductor Lab., Munich (Germany); Hauser, Günter [Max Planck Society Semiconductor Lab., Munich (Germany); Herrmann, Sven [Max Planck Society Semiconductor Lab., Munich (Germany); Schaller, Gerhard [Max Planck Society Semiconductor Lab., Munich (Germany); Schopper, Florian [Max Planck Society Semiconductor Lab., Munich (Germany); Andritschke, Robert [Max Planck Society Semiconductor Lab., Munich (Germany); Boutet, Sébastien [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Krzywinski, Jacek [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Bostedt, Christoph [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Messerschmidt, Marc [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Bozek, John D. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Williams, Garth J. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Bogan, Michael J. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE); Hampton, Christina Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE); Sierra, Raymond G. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE); Starodub, Dmitri [SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE); Gorke, Hubert [Forschungszentrum Julich (Germany); Hau-Riege, Stefan P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frank, Matthias [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Maia, Filipe R. N. C. [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Hajdu, Janos [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Timneanu, Nicusor [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Seibert, M. Marvin [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Andreasson, Jakob [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Rocker, Andrea [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Jönsson, Olof [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Svenda, Martin [Uppsala Univ. (Sweden). Dept. of Cell and Molecular Biology, Lab. of Molecular Biophysics; Holton, James M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Marchesini, Stefano [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Neutze, Richard [Univ. of Gothenburg (Sweden). Dept. of Chemistry, Biochemistry and Biophysics; Schorb, Sebastian [Technische Univ. Berlin (Germany). Inst. fur Optik und Atomare Physik (IOAP); Rupp, Daniela [Technische Univ. Berlin (Germany). Inst. fur Optik und Atomare Physik (IOAP); Adolph, Marcus [Technische Univ. Berlin (Germany). Inst. fur Optik und Atomare Physik (IOAP); Gorkhover, Tais [Technische Univ. Berlin (Germany). Inst. fur Optik und Atomare Physik (IOAP); Andersson, Inger [Swedish Univ. of Agricultural Sciences, Uppsala Biomedical Centre, Uppsala, (Sweden). Dept. of Molecular Biology; Barthelmess, Miriam [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science; Bajt, Saša [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science; Hirsemann, Helmut [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science; Potdevin, Guillaume [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science; Graafsma, Heinz [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science; Nilsson, Björn [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science

    2011-02-03

    X-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded. It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells. Here we present a method for structure determination where single-crystal X-ray diffraction ‘snapshots’ are collected from a fully hydrated stream of nanocrystals using femtosecond pulses from a hard-X-ray free-electron laser, the Linac Coherent Light Source. We prove this concept with nanocrystals of photosystem I, one of the largest membrane protein complexes. More than 3,000,000 diffraction patterns were collected in this study, and a three-dimensional data set was assembled from individual photosystem I nanocrystals (~200 nm to 2 μm in size). We mitigate the problem of radiation damage in crystallography by using pulses briefer than the timescale of most damage processes. This offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage.

  6. Berkeley Lab's ALS generates femtosecond synchrotron radiation

    CERN Document Server

    Robinson, A L

    2000-01-01

    A team at Berkeley's Advanced Light Source has shown how a laser time-slicing technique provides a path to experiments with ultrafast time resolution. A Lawrence Berkeley National Laboratory team has succeeded in generating 300 fs pulses of synchrotron radiation at the ALS synchrotron radiation machine. The team's members come from the Materials Sciences Division (MSD), the Center for Beam Physics in the Accelerator and Fusion Research Division and the Advanced Light Source (ALS). Although this proof-of principle experiment made use of visible light on a borrowed beamline, the laser "time-slicing" technique at the heart of the demonstration will soon be applied in a new bend magnet beamline that was designed specially for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness. The use of X-rays to study the c...

  7. Compressive auto-indexing in femtosecond nanocrystallography

    International Nuclear Information System (INIS)

    Ultrafast nanocrystallography has the potential to revolutionize biology by enabling structural elucidation of proteins for which it is possible to grow crystals with 10 or fewer unit cells on the side. The success of nanocrystallography depends on robust orientation-determination procedures that allow us to average diffraction data from multiple nanocrystals to produce a three-dimensional (3D) diffraction data volume with a high signal-to-noise ratio. Such a 3D diffraction volume can then be phased using standard crystallographic techniques. 'Indexing' algorithms used in crystallography enable orientation determination of diffraction data from a single crystal when a relatively large number of reflections are recorded. Here we show that it is possible to obtain the exact lattice geometry from a smaller number of measurements than standard approaches using a basis pursuit solver. -- Research Highlights: → Femtosecond nanocrystallography relies on orientation-determination procedures to sort data. → Standard approaches using Fourier transforms fail when the number of reflections is small. → Basis pursuit algorithms enable orientation determination using fewer reflections than before.

  8. Curing of Epoxy Resin Induced by Femtosecond Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    LI Yubin; ZHANG Zuoguang

    2005-01-01

    The possibility of curing of epoxy resin induced by femtosecond laser beam was explored through choosing different initiators . Absorption spectroscopy, infrared spectroscopy (IR), stereomicroscopy and scanning electron microscopy (SEM) were applied to analyze the structure of epoxy resin systems after irradiation with a femtosecond laser beam. The experimental results show that the epoxy resin systems containing diaryliodonium salts can be cured by irradiation of Jemtosecond laser pulse, while the systems containing benzoin can not be cured. It is found that diaryliodonium salts decompose under the irradiation of femtosecond laser pulse through multi ( two ) -photon absorption, initiating the ring-opening polymerization of epoxy resin. And the appearance of cured area has a sheet structure consisting of many tiny lamellar structures.

  9. Theory And Practice Of High-energy Femtosecond Fiber Lasers

    CERN Document Server

    Ilday, F O

    2004-01-01

    Ultrafast optics is a rapidly-evolving field encompassing much scientific activity and generating an increasing number of applications. The primary tool of ultra-fast optics, solid state lasers producing energetic femtosecond pulses, remain as a complicated, large and expensive equipment. This thesis presents an experimental and theoretical study of high-energy, femtosecond fiber lasers. The primary emphasis has been the development of practical femtosecond fiber-based sources with performance similar to that of bulk solid state lasers. Since the limitations to performance limitations to pulse energy originate in the strongly-nonlinear nature of the pulse generation dynamics, a thorough understanding of these dynamics has been indispensable. Novel schemes for pulse generation in the presence of strong nonlinearity have been explored. The concept of nonlinearity management has been suggested as a route to two orders of magnitude improvement in the pulse energy of soliton fiber lasers by introducing an optical ...

  10. Large amplitude femtosecond electron dynamics in metal clusters

    CERN Document Server

    Daligault, J

    2003-01-01

    We present a theoretical model that allows us to study linear and non-linear aspects of the femtosecond electron dynamics in metal clusters. The theoretical approach consists in the classical limit of the time-dependent Kohn-Sham equations. The electrons are described by a phase-space distribution function which satisfies a Vlasov-like equation while the ions are treated classically. This allows simulations for clusters containing several hundreds of atoms and extending up to several hundreds of femtoseconds during which the description conserves the fermionic character of the electron distribution. This semi-quantal approach compares very well with the purely quantal treatment. As an application of this approach, we show the prominent role of the electron dynamics during and after the interaction with an intense femtosecond laser pulse.

  11. Response of graphene to femtosecond high-intensity laser irradiation

    International Nuclear Information System (INIS)

    We study the response of graphene to high-intensity, 50-femtosecond laser pulse excitation. We establish that graphene has a high (∼3 x 1012 Wcm-2) single-shot damage threshold. Above this threshold, a single laser pulse cleanly ablates graphene, leaving microscopically defined edges. Below this threshold, we observe laser-induced defect formation leading to degradation of the lattice over multiple exposures. We identify the lattice modification processes through in-situ Raman microscopy. The effective lifetime of chemical vapor deposition grown graphene under femtosecond near-infrared irradiation and its dependence on laser intensity is determined. These results also define the limits of non-linear applications of graphene in femtosecond high-intensity regime.

  12. Tight focusing of femtosecond elliptically polarised vortex light pulses

    Institute of Scientific and Technical Information of China (English)

    Hua Li-Min; Chen Bao-Suan; Chen Zi-Yang; Pu Ji-Xiong

    2011-01-01

    This paper studies the tight focusing properties of femtosecond elliptically polarised vortex light pulses. Based on Richards-Wolf vectorial diffraction integral, the expressions for the electric field, the velocity of the femtosecond light pulse and the total angular momentum of focused pluses are derived. The numerical calculations are also given to illustrate the intensity distribution, phase contour, the group velocity variation and the total angular momentum near the focus. It finds that near the focus the femtosecond elliptically polarised vortex light pulse can travel at various group speeds, that is, slower or faster than light speed in vacuum, depending on the numerical aperture of the focusing objective system. Moreover, it also studies the influence of the numerical aperture of the focusing objective and the time duration of the elliptically polarised vortex light pulse on the total angular momentum distribution in the focused field.

  13. Femtosecond Magnetism When the Orbital Angular Momentum is Quenched

    Science.gov (United States)

    Si, M. S.; Yang, D. Z.; Xue, D. S.; Zhang, G. P.

    2015-11-01

    In femtosecond magnetism, a femtosecond laser pulse affects the spin moment only indirectly through the orbital angular momentum and the spin-orbit coupling. A long-standing puzzle is what happens if the orbital angular momentum itself is quenched. Here, we employ a four-level system to resolve this puzzle. The results show that the quenching of the orbital angular moment in the ground state has no direct relation to the spin moment change. By contrast, the orbital moment can be restored partially after the pulsed optical excitation and can affect the demagnetization. Importantly, this study confirms that the orbital moment indeed responds to the laser field faster than spin if the pulse duration is short, consistent with the recent time-resolved X-ray magnetic circular dichroism experiment. Therefore, our finding shines new light on femtosecond magnetism.

  14. Compact femtosecond fiber laser with integrated optical components

    International Nuclear Information System (INIS)

    A compact femtosecond ytterbium-doped fiber laser has been developed with integrated optical components. The femtosecond fiber laser oscillator was miniaturized by integrating the intracavity wavelength division multiplexer and optical isolator with collimators, and placing a quarter-wave plate before a transmission grating pair to get light retroflection from the intracavity dispersive delay line. Stretched-pulse mode-locking could be self-started at a repetition rate of 65 MHz with pump power as low as 100 mW. The compact femtosecond fiber laser oscillator could be optimized to generate 86 fs pulse duration and 0.5 nJ pulse energy. (paper)

  15. Tight focusing of femtosecond elliptically polarised vortex light pulses

    International Nuclear Information System (INIS)

    This paper studies the tight focusing properties of femtosecond elliptically polarised vortex light pulses. Based on Richards—Wolf vectorial diffraction integral, the expressions for the electric field, the velocity of the femtosecond light pulse and the total angular momentum of focused pluses are derived. The numerical calculations are also given to illustrate the intensity distribution, phase contour, the group velocity variation and the total angular momentum near the focus. It finds that near the focus the femtosecond elliptically polarised vortex light pulse can travel at various group speeds, that is, slower or faster than light speed in vacuum, depending on the numerical aperture of the focusing objective system. Moreover, it also studies the influence of the numerical aperture of the focusing objective and the time duration of the elliptically polarised vortex light pulse on the total angular momentum distribution in the focused field. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  16. Analysis of the halo background in femtosecond slicing experiments.

    Science.gov (United States)

    Schick, Daniel; Le Guyader, Loïc; Pontius, Niko; Radu, Ilie; Kachel, Torsten; Mitzner, Rolf; Zeschke, Thomas; Schüßler-Langeheine, Christian; Föhlisch, Alexander; Holldack, Karsten

    2016-05-01

    The slicing facility FemtoSpeX at BESSY II offers unique opportunities to study photo-induced dynamics on femtosecond time scales by means of X-ray magnetic circular dichroism, resonant and non-resonant X-ray diffraction, and X-ray absorption spectroscopy experiments in the soft X-ray regime. Besides femtosecond X-ray pulses, slicing sources inherently also produce a so-called `halo' background with a different time structure, polarization and pointing. Here a detailed experimental characterization of the halo radiation is presented, and a method is demonstrated for its correct and unambiguous removal from femtosecond time-resolved data using a special laser triggering scheme as well as analytical models. Examples are given for time-resolved measurements with corresponding halo correction, and errors of the relevant physical quantities caused by either neglecting or by applying a simplified model to describe this background are estimated. PMID:27140149

  17. Femtosecond laser-assisted cataract surgery: A current review

    Directory of Open Access Journals (Sweden)

    Majid Moshirfar

    2011-01-01

    Full Text Available To evaluate the safety, efficacy, advantages, and limitations of femtosecond laser-assisted cataract surgery through a review of the literature. A PubMed search was conducted using topic-appropriate keywords to screen and select articles. Initial research has shown appropriate safety and efficacy of femtosecond laser-assisted cataract surgery, with improvements in anterior capsulotomy, phacofragmentation, and corneal incision. Limitations of these studies include small sample size and short-term follow-up. Cost-benefit analysis has not yet been addressed. Preliminary data for femtosecond laser-assisted cataract surgery shows appropriate safety and efficacy, and possible advantage over conventional cataract surgery. Questions to eventually be answered include comparisons of long-term postoperative complication rates-including infection and visual outcomes-and analysis of contraindications and financial feasibility.

  18. A Novel Femtosecond Laser System for Attosecond Pulse Generation

    Directory of Open Access Journals (Sweden)

    Jianqiang Zhu

    2012-01-01

    Full Text Available We report a novel ultrabroadband high-energy femtosecond laser to be built in our laboratory. A 7-femtosecond pulse is firstly stretched by an eight-pass offner stretcher with a chirp rate 15 ps/nm, and then energy-amplified by a two-stage optical parametric chirped pulse amplification (OPCPA. The first stage as preamplification with three pieces of BBO crystals provides the majority of the energy gain. At the second stage, a YCOB crystal with the aperture of ~50 mm is used instead of the KDP crystal as the gain medium to ensure the shortest pulse. After the completion, the laser will deliver about 8 J with pulse duration of about 10 femtoseconds, which should be beneficial to the attosecond pulse generation and other ultrafast experiments.

  19. Flexible gratings fabricated in polymeric plate using femtosecond laser irradiation

    Science.gov (United States)

    Park, Jung-Kyu; Cho, Sung-Hak

    2011-05-01

    Flexible gratings embedded in poly-dimethlysiloxane (PDMS) were fabricated using femtosecond laser pulses. Photo-induced gratings in a flexible PDMS plate were directly written by a high-intensity femtosecond (130 fs) Ti: Sapphire laser ( λp=800 nm). Refractive index modifications with 4 μm diameters were photo-induced after irradiation of the femtosecond pulses with peak intensities of more than 1×10 11 W/cm 2. The graded refractive index profile was fabricated to be symmetric around the center of the focal point. The diffraction efficiency of the grating samples is measured by an He-Ne laser. The maximum value of refractive index change (Δ n) in the laser-modified regions was estimated to be approximately 3.17×10 -3.

  20. An optimization of Raman effects in tandem-pumped Yb-doped kilowatt fiber amplifiers

    Science.gov (United States)

    Zhang, Tianzi; Ding, Yingchun; Liu, Zhongxuan; Gong, Wupeng

    2015-07-01

    Kilowatt Ytterbium-doped fiber laser is found widespread application in medical technology, industry and military areas. At present, most of the multi-kilowatt single-mode fiber lasers are achieved by tandem-pumped master oscillator power-amplifier (MOPA) system. When the laser output power reaches kilowatt, the output will be strongly affected by nonlinear effects in the amplifier. The Stimulated Raman Scattering effects is known as the major restrictions to the increase of output signal power. Up to now, Raman effects in conventional diode-pumped amplifier have been well studied while the Raman effects in tandem-pumped has not yet been thoroughly analyzed. In this paper, a theoretical analysis of Raman effects using numerical solution of steady-state rate equations in kilowatts tandem-pumped ytterbium-doped fiber amplifiers is presented. The numerical simulation describing output power characteristics and laser distribution along the fiber is carried under the co-directional end-pumping. Furthermore, an optimization of Raman effects is discussed, which provides a solid foundation for achieving a higher fiber laser output.

  1. Gain-switched, Yb-doped, all-fiber laser with narrow bandwidth

    DEFF Research Database (Denmark)

    Larsen, Casper; Giesberts, Martin; Nyga, Sebastian; Fitzau, Oliver; Hoffmann, Hans Dieter; Bang, Ole

    2013-01-01

    We demonstrate that an all-fiber, narrow bandwidth, high pulse energy pulsed laser can be constructed from commercially available components by applying gain-switching. After single-stage amplification the pulses are frequency doubled in ppSLT with high efficiency....

  2. Properties of Er and Yb Doped Gallium nitride layers fabricated by magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Prajzler, V.; Burian, Z.; Hüttel, I.; Špirková, J.; Hamáček, J.; Oswald, J.; Zavadil, Jiří; Peřina, Vratislav

    2006-01-01

    Roč. 46, č. 6 (2006), s. 49-55. ISSN 1210-2709 R&D Projects: GA ČR(CZ) GA102/06/0424 Institutional research plan: CEZ:AV0Z20670512; CEZ:AV0Z10480505 Keywords : fluorescence * gallium * rare earth compounds Subject RIV: BM - Solid Matter Physics ; Magnetism

  3. Tm-Yb Doped Optical Fiber Performance with Variation of Host-Glass Composition

    Directory of Open Access Journals (Sweden)

    Anirban Dhar

    2014-01-01

    Full Text Available The fabrication process of Thulium-Ytterbium doped optical fiber comprising different host glass through the Modified Chemical Vapor Deposition (MCVD coupled with solution doping technique is presented. The material and optical performance of different fibers are compared with special emphasis on their lasing efficiency for 2 µm application.

  4. Demonstration of a homogeneous Yb-doped core fully aperiodic large-pitch fiber laser.

    Science.gov (United States)

    Dauliat, Romain; Benoît, Aurélien; Darwich, Dia; Jamier, Raphaël; Kobelke, Jens; Grimm, Stephan; Schuster, Kay; Roy, Philippe

    2016-08-10

    The first demonstration of a 40 μm core homogeneously ytterbium-doped fully aperiodic large-pitch fiber laser, to the best of our knowledge, is reported here. In this concept, the amplification of unwanted high-order modes is prevented by means of an aperiodic inner-cladding structure, while the core and inner-cladding material has a higher refractive index than pure silica. In a laser configuration, up to 252 W of extracted power, together with an optical-to-optical efficiency of 63% with respect to the incident pump power, have been achieved. While an average M2 of 1.4 was measured, the emitted power becomes temporally unstable when exceeding 95 W, owing to the occurrence of modal instabilities. PMID:27534463

  5. Ce and Yb doped InP layers grown for radiation detection

    Czech Academy of Sciences Publication Activity Database

    Zavadil, Jiří; Procházková, Olga; Žďánský, Karel; Gladkov, Petar

    2007-01-01

    Roč. 4, č. 4 (2007), s. 1444-1447. ISSN 1610-1634. [EXMATEC 2006 - International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & Technologies /8./. Cádiz, 14.05.2006-17.05.2006] R&D Projects: GA ČR GA102/06/0153 Institutional research plan: CEZ:AV0Z20670512 Keywords : semiconductors * photoluminescence * galvanomagnetic effects Subject RIV: CA - Inorganic Chemistry

  6. Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser

    Indian Academy of Sciences (India)

    Usha Chakravarty; Antony Kuruvilla; Rajpal Singh; B N Upadhyay; K S Bindra; S M Oak

    2014-02-01

    In this paper we report linearly polarized high average power passive Q-switched ytterbium-doped photonic crystal fibre laser with a Cr4+:YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% was achieved. Measured polarization extinction ratio (PER) of the Q-switched laser output was 10.5 dB.

  7. How do traces of thulium explain photodarkening in Yb doped fibers?

    Science.gov (United States)

    Peretti, R; Jurdyc, A-M; Jacquier, B; Gonnet, Cédric; Pastouret, Alain; Burov, Ekaterina; Cavani, Olivier

    2010-09-13

    Ytterbium doped fiber lasers are known to be impacted by the creation of color centers during lasing so called photodarkening. This defect creation was investigated in a spectroscopic point of view, showing the presence of thulium traces (ppb) in the ytterbium doped fiber. Moreover, this contamination exhibit luminescence in the UV range under 976 nm excitation of the ytterbium-doped fiber. In adding more thulium to an ytterbium-doped fiber it was shown that thulium strongly impact the defects creation process, involved in photodarkening. PMID:20940938

  8. Tm-Yb Doped Optical Fiber Performance with Variation of Host-Glass Composition

    OpenAIRE

    Anirban Dhar; Atasi Pal; Shyamal Das; Ranjan Sen

    2014-01-01

    The fabrication process of Thulium-Ytterbium doped optical fiber comprising different host glass through the Modified Chemical Vapor Deposition (MCVD) coupled with solution doping technique is presented. The material and optical performance of different fibers are compared with special emphasis on their lasing efficiency for 2 µm application.

  9. Yb-doped silica glass and photonic crystal fiber based on laser sintering technology

    Science.gov (United States)

    Zhang, Wei; Wu, Jiale; Zhou, Guiyao; Xia, Changming; Liu, Jiantao; Tian, Hongchun; Liang, Wanting; Hou, Zhiyun

    2016-03-01

    We demonstrate the fabricating method for Yb3+-doped silica glass and double-cladding large mode area photonic crystal fiber (LMA PCF) based on laser sintering technology combined with a liquid phase doping method. The doped material prepared shows the amorphous property and the hydroxyl content is approximately 40 ppm. The attenuation of the fabricated LMA PCF is 14.2 dB m-1 at 976 nm, and the lowest value is 0.25 dB m-1 at 1200 nm. The laser slope efficiency is up to 70.2%.

  10. 3.5-GHz intra-burst repetition rate ultrafast Yb-doped fiber laser

    Science.gov (United States)

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Akçaalan, Önder; Ilday, F. Ömer

    2016-05-01

    We report on an all-fiber Yb laser amplifier system with an intra-burst repetition rate of 3.5 GHz. The system is able to produce minimum of 15-ns long bursts containing approximately 50 pulses with a total energy of 215 μJ at a burst repetition rate of 1 kHz. The individual pulses are compressed down to the subpicosecond level. The seed signal from a 108 MHz fiber oscillator is converted to approximately 3.5 GHz by a multiplier consisting of six cascaded 50/50 couplers, and then amplified in ten stages. The highly cascaded amplification suppresses amplified spontaneous emission at low repetition rates. Nonlinear interactions between overlapping pulses within a burst is also discussed.

  11. Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Shirakawa, Akira; Maurayama, Hiroki; Ken-ichi, Ueda; Lyngsøe, Jens Kristian; Broeng, Jes

    2010-01-01

    Ytterbium-doped photonic-bandgap fiber sources operationg at the long-wavelength edge of the ytterbium gain band are being investigated for high power amplification. Artificial shaping of the gain spectrum by the characteristic distributed filtering effect of the photonic bandgap enables spontane...

  12. Graphene incorporated Q-switching of a polarization-maintaining Yb-doped fiber laser

    International Nuclear Information System (INIS)

    Environmentally-stable, all-polarization-maintaining Q-switching ytterbium-doped fiber laser was demonstrated using graphene as saturable absorber. By optically driving deposition of graphene onto the fiber connector, the saturable absorber is fabricated and inserted into the laser cavity to construct the Q-switching fiber laser. The maximum average output power of 15.6 mW at a repetition rate of 110 kHz, which corresponds to a single pulse energy of 141.8 nJ, was achieved. They are the maximum average output power and the highest single pulse energy reported so far for graphene Q-switched fiber lasers

  13. Electrical and microstructural properties of Yb-doped CeO2

    Directory of Open Access Journals (Sweden)

    B. Matović

    2014-06-01

    Full Text Available Nanopowdered Ce1−xYbxO2−δ solid solutions (0 ≤ x ≤ 0.2 were synthesized by a self-propagating room temperature synthesis. XRD and SEM were used to study the properties of these materials as well as the Yb solubility in CeO2 lattice. Results showed that all the obtained powders were solid solutions with a fluorite-type crystal structure and with nanometric particle size. The average size of Ce1−xYbxO2−δ particles was approximately 3 nm. Electrochemical impedance spectroscopy for the sintered pellets depicted that it was possible to separate Rbulk and Rgb in the temperature interval of 550–800 °C. The activation energy for the bulk conduction was 1.03 eV and for grain boundary conduction was 1.14 eV. Grain boundary resistivity dominates over the other resistivities. These measurements confirmed that Yb3+-doped CeO2 material had a potential as electrolyte for intermediate-temperature solid oxide fuel cell applications.

  14. Thermal Properties of Transparent Yb-Doped YAG Ceramics at Elevated Temperatures

    Czech Academy of Sciences Publication Activity Database

    Hostaša, J.; Matějíček, Jiří; Nait-Ali, B.; Smith, D.S.; Pabst, W.; Esposito, L.

    2014-01-01

    Roč. 97, č. 8 (2014), s. 2602-2606. ISSN 0002-7820 Institutional support: RVO:61389021 Keywords : yttrium aluminium garnet * Yb: YAG * thermal diffusivity Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.610, year: 2014 http://onlinelibrary.wiley.com/doi/10.1111/jace.13015/abstract

  15. Femtosecond laser three-dimensional micro- and nanofabrication

    International Nuclear Information System (INIS)

    The rapid development of the femtosecond laser has revolutionized materials processing due to its unique characteristics of ultrashort pulse width and extremely high peak intensity. The short pulse width suppresses the formation of a heat-affected zone, which is vital for ultrahigh precision fabrication, whereas the high peak intensity allows nonlinear interactions such as multiphoton absorption and tunneling ionization to be induced in transparent materials, which provides versatility in terms of the materials that can be processed. More interestingly, irradiation with tightly focused femtosecond laser pulses inside transparent materials makes three-dimensional (3D) micro- and nanofabrication available due to efficient confinement of the nonlinear interactions within the focal volume. Additive manufacturing (stereolithography) based on multiphoton absorption (two-photon polymerization) enables the fabrication of 3D polymer micro- and nanostructures for photonic devices, micro- and nanomachines, and microfluidic devices, and has applications for biomedical and tissue engineering. Subtractive manufacturing based on internal modification and fabrication can realize the direct fabrication of 3D microfluidics, micromechanics, microelectronics, and photonic microcomponents in glass. These microcomponents can be easily integrated in a single glass microchip by a simple procedure using a femtosecond laser to realize more functional microdevices, such as optofluidics and integrated photonic microdevices. The highly localized multiphoton absorption of a tightly focused femtosecond laser in glass can also induce strong absorption only at the interface of two closely stacked glass substrates. Consequently, glass bonding can be performed based on fusion welding with femtosecond laser irradiation, which provides the potential for applications in electronics, optics, microelectromechanical systems, medical devices, microfluidic devices, and small satellites. This review paper

  16. Femtosecond laser three-dimensional micro- and nanofabrication

    Energy Technology Data Exchange (ETDEWEB)

    Sugioka, Koji, E-mail: ksugioka@riken.jp [RIKEN Center for Advanced Photonics, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Cheng, Ya, E-mail: ya.cheng@siom.ac.cn [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

    2014-12-15

    The rapid development of the femtosecond laser has revolutionized materials processing due to its unique characteristics of ultrashort pulse width and extremely high peak intensity. The short pulse width suppresses the formation of a heat-affected zone, which is vital for ultrahigh precision fabrication, whereas the high peak intensity allows nonlinear interactions such as multiphoton absorption and tunneling ionization to be induced in transparent materials, which provides versatility in terms of the materials that can be processed. More interestingly, irradiation with tightly focused femtosecond laser pulses inside transparent materials makes three-dimensional (3D) micro- and nanofabrication available due to efficient confinement of the nonlinear interactions within the focal volume. Additive manufacturing (stereolithography) based on multiphoton absorption (two-photon polymerization) enables the fabrication of 3D polymer micro- and nanostructures for photonic devices, micro- and nanomachines, and microfluidic devices, and has applications for biomedical and tissue engineering. Subtractive manufacturing based on internal modification and fabrication can realize the direct fabrication of 3D microfluidics, micromechanics, microelectronics, and photonic microcomponents in glass. These microcomponents can be easily integrated in a single glass microchip by a simple procedure using a femtosecond laser to realize more functional microdevices, such as optofluidics and integrated photonic microdevices. The highly localized multiphoton absorption of a tightly focused femtosecond laser in glass can also induce strong absorption only at the interface of two closely stacked glass substrates. Consequently, glass bonding can be performed based on fusion welding with femtosecond laser irradiation, which provides the potential for applications in electronics, optics, microelectromechanical systems, medical devices, microfluidic devices, and small satellites. This review paper

  17. Femtosecond time-resolved MeV electron microscopy

    International Nuclear Information System (INIS)

    The direct visualization of fundamental dynamic processes in matter occurring on femtosecond time scales over sub-nanometer (even atomic) spatial dimensions has long been a goal in science. In this paper, the development of a femtosecond time-resolved relativistic transmission electron microscopy (FsTEM) based on a photocathode radio-frequency (RF) gun is reported. The requirements and limitations of the beam parameters used in FsTEM are discussed. Finally, some demonstrations of relativistic ultrafast electron diffraction measurement using the RF gun are presented. (author)

  18. Femtosecond time-resolved electronic relaxation dynamics in tetrathiafulvalene

    Energy Technology Data Exchange (ETDEWEB)

    Staedter, D.; Polizzi, L. [Laboratoire de Collisions, Agrégats et Réactivité, IRSAMC, Université de Toulouse-CNRS, 31062 Toulouse (France); Thiré, N. [Laboratoire de Collisions, Agrégats et Réactivité, IRSAMC, Université de Toulouse-CNRS, 31062 Toulouse (France); INRS-EMT, Advanced Laser Light Source, 1650 Lionel-Boulet Blvd., Varennes, Quebec J3X1S2 (Canada); Mairesse, Y. [Centre des Laser Intenses et Applications, Université de Bordeaux-CNRS, 33405 Talence (France); Mayer, P. [Chemistry Department, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada); Blanchet, V., E-mail: blanchet@celia.u-bordeaux1.fr [Laboratoire de Collisions, Agrégats et Réactivité, IRSAMC, Université de Toulouse-CNRS, 31062 Toulouse (France); Centre des Laser Intenses et Applications, Université de Bordeaux-CNRS, 33405 Talence (France)

    2015-05-21

    In the present paper, the ultrafast electronic relaxation of tetrathiafulvalene (TTF) initiated around 4 eV is studied by femtosecond time-resolved velocity-map imaging. The goal is to investigate the broad double structure observed in the absorption spectrum at this energy. By monitoring the transients of the parent cation and its fragments and by varying the pump and the probe wavelengths, two internal conversions and intramolecular vibrational relaxation are detected both on the order of a few hundred of femtoseconds. Photoelectron images permit the assignment of a dark electronic state involved in the relaxation. In addition, the formation of the dimer of TTF has been observed.

  19. Materials processing with a tightly focused femtosecond laser vortex pulse.

    Science.gov (United States)

    Hnatovsky, Cyril; Shvedov, Vladlen G; Krolikowski, Wieslaw; Rode, Andrei V

    2010-10-15

    In this Letter we present the first (to our knowledge) demonstration of material modification using tightly focused single femtosecond laser vortex pulses. Double-charge femtosecond vortices were synthesized with a polarization-singularity beam converter based on light propagation in a uniaxial anisotropic medium and then focused using moderate- and high-NA optics (viz., NA=0.45 and 0.9) to ablate fused silica and soda-lime glass. By controlling the pulse energy, we consistently machine micrometer-size ring-shaped structures with <100nm uniform groove thickness. PMID:20967085

  20. Formation of Elemental Distribution in Glasses by Femtosecond Laser Irradiation

    International Nuclear Information System (INIS)

    We report on the fabrication of optical waveguides and the precipitation of nonlinear optical crystals inside glass caused by local element migration with high-repetition femtosecond laser irradiation. Elements that contribute to the high refractive index migrated to the center of the focal region because of the femtosecond laser irradiation in phosphate and borate glasses. Based on this result, we successfully wrote optical waveguides in these glasses, where element distributions were continuously induced along a path traversed by the focal point. Furthermore, we succeeded in space-selective precipitation of nonlinear optical crystals such as β-BBO inside glass by controlling the thermophysical property (crystallization temperature).

  1. Lattice dynamics of femtosecond laser-excited antimony

    Science.gov (United States)

    Abdel-Fattah, Mahmoud Hanafy; Bugayev, Aleksey; Elsayed-Ali, Hani E.

    2016-07-01

    Ultrafast electron diffraction is used to probe the lattice dynamics of femtosecond laser-excited antimony thin film. The temporal hierarchies of the intensity and position of diffraction orders are monitored. The femtosecond laser excitation of antimony film was found to lead to initial compression after the laser pulse, which gives way to tension vibrating at new equilibrium displacement. A damped harmonic oscillator model, in which the hot electron-blast force contributes to the driving force of oscillations in lattice spacing, is used to interpret the data. The electron-phonon energy-exchange rate and the electronic Grüneisen parameter were obtained.

  2. Ultrafast thermoelasticity modeling of microbump formation irradiated by femtosecond laser

    Institute of Scientific and Technical Information of China (English)

    Zehua Han; Changhe Zhou; Enwen Dai

    2008-01-01

    Finite element method and ultrafast thermoelasticity model are combined to simulate the microbump formation irradiated by a femtosecond laser. It has been shown that the effect of microbump formation is related to the characteristic of incident femtosecond laser and the thermoelasticity properties of the film. The numerical results exhibit good agreements with the experimental results in both the shape and height of the conical microbump structure, which verify the effectiveness of the ultrafast thermoelasticity model in experiments. It should be helpful for selecting appropriate materials for nanotexturing of thin films by ultrafast lasers.

  3. A Novel Femtosecond Laser System for Attosecond Pulse Generation

    OpenAIRE

    Jianqiang Zhu; Xinglong Xie; Meizhi Sun; Qunyu Bi; Jun Kang

    2012-01-01

    We report a novel ultrabroadband high-energy femtosecond laser to be built in our laboratory. A 7-femtosecond pulse is firstly stretched by an eight-pass offner stretcher with a chirp rate 15 ps/nm, and then energy-amplified by a two-stage optical parametric chirped pulse amplification (OPCPA). The first stage as preamplification with three pieces of BBO crystals provides the majority of the energy gain. At the second stage, a YCOB crystal with the aperture of ~50 mm is used instead of the K...

  4. Materials processing with a tightly focused femtosecond vortex laser pulse

    CERN Document Server

    Hnatovsky, Cyril; Krolikowski, Wieslaw; Rode, Andrei V

    2010-01-01

    This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than 100 nm uniform groove thickness.

  5. Materials processing with tightly focused femtosecond vortex laser beams

    CERN Document Server

    Hnatovsky, Cyril; Krolikowski, Wieslaw; Rode, Andrei V

    2010-01-01

    This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than 100 nm uniform groove thickness.

  6. Femtosecond Optical Parametric Amplifier for Petawatt Nd:Glass Lasers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Min; QIAN Lie-Jia; YUAN Peng; LUO Hang; ZHU He-Yuan; ZHU Qi-Hua; WEI Xiao-Feng; FAN Dian-Yuan

    2006-01-01

    @@ We study a femtosecond Ti:sapphire laser pumped optical parametric amplifier (OPA) at 1053nm. The OPA generates stable signal pulses with duration smaller than 100 fs, wavelength drift smaller than 0.5nm, and pulse-to-pulse fluctuation of about ±4%, by employing an external seeder. In a terawatt laser pumped large-aperture LiNbO3 OPA, pulse energy at signal has been scaled up to 4mJ. This m J-class femtosecond OPA at 1053nm presents a feasible alternative to optical parametric chirped-pulse amplification, and is ready to be applied to petawatt lasers.

  7. Optical diagnostics of femtosecond laser plasmas

    Institute of Scientific and Technical Information of China (English)

    LI; Yutong

    2001-01-01

    [1]Benattar, R., Popovics, C., Sigel, R., Polarized light interferometer for laser fusion studies, Rev. Sci. Instrum., 979, 50(2): 583.[2]Young, P. E., Hammer, J. H., Wilks, S. C. et al., Laser beam propagation and channel formation in underdense plasmas, Phys. Plasmas, 995, 2(7): 2825.[3]Zhang, P., He, J.T., Chen, D.B. et al., Effects of a prepulse on γ-ray radiation produced by a femtosecond laser with only mJ energy, Phys. Rev. E., 998, 57: R3746.[4]Stamper, J. A., Review on spontaneous magnetic fields in laser-produced plasmas: phenomena and measurements, Laser and Particle Beams, 99, 9(4): 84.[5]Stamper, J. A., McLean, E. A., Ripin, B. H., Studies of spontaneous magnetic fields in laser-produced plasmas by Faraday rotation, Phys. Rev. Lett., 978, 40(8): 77.[6]Raven, A., Willi, O., Rumsby, P. T., Megagauss magnetic field profiles in laser-produced plasmas, Phys. Rev. Lett., 978, 4(8): 554.[7]Burgess, M. D. J., Luther-Davis, B., Nugent, K. A., An experimental study of magnetic fields in plasmas created by high intensity one micron laser radiation, Phys. Fluids, 985, 28(7): 2286.[8]Borghesi, M., Mackinnon, A. J., Bell, A. R. et al., Megagauss magnetic field generation and plasma jet formation on solid targets irradiated by an ultraintense picosecond laser pulse, Phys. Rev. Lett., 998, 8(): 2.

  8. Femtosecond laser microchannels fabrication based on electrons dynamics control using temporally or spatially shaped pulses

    Science.gov (United States)

    Yan, Xueliang; Hu, Jie; Li, Xiaowei; Xia, Bo; Liu, Pengjun; Lu, Yongfeng; Jiang, Lan

    2014-11-01

    With ultrashort pulse durations and ultrahigh power densities, femtosecond laser presents unique advantages of high precision and high quality fabrication of microchannels in transparent materials. In our study, by shaping femtosecond laser pulse energy distribution in temporal or spatial domains, localized transient electrons dynamics and the subsequent processes, such as phase changes, can be controlled, leading to the dramatic increases in the capability of femtosecond laser microchannels fabrication. The temporally shaped femtosecond laser pulse trains can significantly enhance the material removal rate in both water-assisted femtosecond laser drilling and femtosecond laser irradiation followed by chemical etching. Besides, high-aspect-ratio and small-diameter microchannels are drilled by spatially shaped femtosecond laser pulses.

  9. Monitoring femtosecond laser microscopic photothermolysis with multimodal microscopy (Conference Presentation)

    Science.gov (United States)

    Huang, Yimei; Lui, Harvey; Zhao, Jianhua; McLean, David I.; Zeng, Haishan

    2016-02-01

    Photothermolysis induced by femtosecond (fs) lasers may be a promising modality in dermatology because of its advantages of high precision due to multiphoton absorption and deeper penetration due to the use of near infrared wavelengths. Although multiphoton absorption nonlinear effects are capable of precision targeting, the femtosecond laser photothermolysis could still have effects beyond the targeted area if a sufficiently high dose of laser light is used. Such unintended effects could be minimized by real time monitoring photothermolysis during the treatment. Targeted photothermolytic treatment of ex vivo mouse skin dermis was performed with tightly focused fs laser beams. Images of reflectance confocal microscopy (RCM), second harmonic generation (SHG), and two-photon fluorescence (TPF) of the mouse skins were obtained with integrated multimodal microscopy before, during, and after the laser treatment. The RCM, SHG, and TPF signal intensities of the treatment areas changed after high power femtosecond laser irradiation. The intensities of the RCM and SHG signals decreased when the tissue was damaged, while the intensity of the TPF signal increased when the photothermolysis was achieved. Moreover, the TPF signal was more susceptible to the degree of the photothermolysis than the RCM and SHG signals. The results suggested that multimodal microscopy is a potentially useful tool to monitor and assess the femtosecond laser treatment of the skin to achieve microscopic photothermolysis with high precision.

  10. Filming Femtosecond Molecular Movies with X-ray Pulses

    DEFF Research Database (Denmark)

    Kjær, Kasper Skov

    This thesis describes the investigation of time-resolved phenomena using X-ray techniques, and in particular the new possibilities and challenges arising from the application of these techniques on the femtosecond time-scale. The thesis will review the processes following laser excitation of mole...

  11. Tesla coil discharges guided by femtosecond laser filaments in air

    OpenAIRE

    Brelet, Yohann; Houard, Aurélien; Arantchouk, Leonid; Forestier, Benjamin; Liu, Yi; Prade, Bernard; Carbonnel, Jérôme; André, Yves-Bernard; Mysyrowicz, André

    2012-01-01

    International audience A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the discharges are performed in air by femtosecond laser filaments.

  12. Tesla coil discharges guided by femtosecond laser filaments in air

    Science.gov (United States)

    Brelet, Yohann; Houard, Aurélien; Arantchouk, Leonid; Forestier, Benjamin; Liu, Yi; Prade, Bernard; Carbonnel, Jérôme; André, Yves-Bernard; Mysyrowicz, André

    2012-04-01

    A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the discharges are performed in air by femtosecond laser filaments.

  13. Development of femtosecond optical frequency comb laser tracker

    Science.gov (United States)

    Yang, Ju-qing; Zhou, Wei-hu; Dong, Deng-feng; Zhang, Zi-li; Lao, Da-bao; Ji, Rong-yi; Wang, Da-yong

    2016-01-01

    A new type femtosecond laser tracker is one high precision measurement instrument with urgent need in science research region and industrial manufacture field. This paper focuses on the operational principle and the structure development of the femtosecond laser tracer, and the method of error compensation as well. The system modules were studied and constructed. The femtosecond frequency comb module was firstly analyzed and developed. The femtosecond laser frequency comb performed perfectly high precise distance measurement for laser tracker. The experimental result showed that the stability of repetition rate reached 3.0×10-12@1s and the stability of carrier envelop offset reached 1.0×10-10@1s. The initial experiment showed that measurement error was less than 1ppm. Later the error compensation module was introduced, and the optoelectronic aiming and tracking control module was built. The actual test result showed that the stability of miss distance was better than 2.0 μm, the tracking speed could reach 2m/s.

  14. Femtosecond fibre laser with a hybrid linear-ring cavity

    International Nuclear Information System (INIS)

    A new type of a femtosecond self-mode-locked erbium fibre laser is proposed and fabricated. The original hybrid design of the laser cavity taking advantage of ring and linear cavity lasers allows continuous tuning of the pulse repetition rate in a broad range (more that 30 kHz) and provides a high reliability of the self-mode-locking regime. (letters)

  15. Investigation of vibrational characteristics in BBO crystals by femtosecond CARS

    Science.gov (United States)

    Xia, Yuanqin; Zhao, Yang; Wang, Zi; Zhang, Sheng; Dong, Zhiwei; Chen, Deying; Zhang, Zhonghua

    2012-10-01

    Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) is utilized to study the ultrafast vibrational dynamics in BBO crystals at room temperature. Time-resolved two-beam and three-beam CARS are detected. The vibrational dephasing time is analyzed and the changes of vibrational mode intensities with the polarization of pump pulses are observed.

  16. Optical detection and femtosecond spectroscopy of a single nanoparticle

    International Nuclear Information System (INIS)

    An extension to semiconductor quantum dots of the spatial-modulation technique, demonstrated for the optical detection and linear spectroscopy of a single metal nanoparticle, is described. The association of this approach to a high sensitivity femtosecond pump–probe setup is discussed and applied to the investigation of the acoustic vibration of a single silver nanoparticle

  17. Femtosecond carotenoid to retinal energy transfer in xanthorhodopsin

    Czech Academy of Sciences Publication Activity Database

    Polívka, Tomáš; Balashov, S.P.; Chábera, P.; Imasheva, E.S.; Yartsev, A.; Sundström, V.; Lanyi, J.K.

    2009-01-01

    Roč. 96, č. 6 (2009), s. 2268-2277. ISSN 0006-3495 R&D Projects: GA AV ČR IAA608170604 Institutional research plan: CEZ:AV0Z50510513 Keywords : energy transfer * carotenoids * femtosecond spectroscopy Subject RIV: BO - Biophysics Impact factor: 4.390, year: 2009

  18. Influence of liquid environments on femtosecond laser ablation of silicon

    International Nuclear Information System (INIS)

    Liquid-assisted ablation of solids by femtosecond laser pulses has proved to be an efficient tool for highly precise microfabrication, which evokes numerous research interests in recent years. In this paper, we systematically investigate the interaction of femtosecond laser pulses with silicon wafer in water, alcohol, and as a comparison, in air. After producing a series of multiple-shot craters on a silicon wafer in the three types of environments, surface morphologies and femtosecond laser-induced periodic surface structures are comparatively studied via the scanning electron microscope investigations. Meanwhile, the influence of liquid mediums on ablation threshold fluence and ablation depth is also numerically analyzed. The experimental results indicate that the ablation threshold fluences of silicon are reduced by the presence of liquids (water/alcohol) and ablation depths of craters are deepened in ambient water. Furthermore, smoother surfaces tend to be obtained in alcohol-mediated ablation at smaller shot numbers. Finally, the evolution of the femtosecond laser-induced periodic surface structures in air, water and alcohol is also discussed.

  19. Femtosecond laser micromachining of a single-crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Q. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)]. E-mail: cqfeng@engin.umich.edu; Picard, Y.N. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Liu, H. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109 (United States); Yalisove, S.M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Mourou, G. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109 (United States); Pollock, T.M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2005-09-15

    Femtosecond laser micromachining of a single crystal superalloy has been investigated. Laser-induced ablation and associated damage was examined by means of scanning electron microscopy and transmission electron microscopy. These studies indicate a complete absence of conventional processing defects in the vicinity of machining area. The residual roughness of the machined surface was in the sub-micron range.

  20. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    Science.gov (United States)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-05-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  1. Femtosecond two-dimensional spectroscopy of molecular motion in liquids

    NARCIS (Netherlands)

    Steffen, T; Duppen, K.

    1996-01-01

    Intermolecular motion in CS2 and benzene is investigated by femtosecond nonresonant four- and six-wave mixing. Impulsive stimulated six-wave mixing yields new information on dephasing of coherent nuclear motion, not accessible from four-wave mixing experiments. The results cannot be modeled by two i

  2. Polyatomic molecules under intense femtosecond laser irradiation.

    Science.gov (United States)

    Konar, Arkaprabha; Shu, Yinan; Lozovoy, Vadim V; Jackson, James E; Levine, Benjamin G; Dantus, Marcos

    2014-12-11

    Interaction of intense laser pulses with atoms and molecules is at the forefront of atomic, molecular, and optical physics. It is the gateway to powerful new tools that include above threshold ionization, high harmonic generation, electron diffraction, molecular tomography, and attosecond pulse generation. Intense laser pulses are ideal for probing and manipulating chemical bonding. Though the behavior of atoms in strong fields has been well studied, molecules under intense fields are not as well understood and current models have failed in certain important aspects. Molecules, as opposed to atoms, present confounding possibilities of nuclear and electronic motion upon excitation. The dynamics and fragmentation patterns in response to the laser field are structure sensitive; therefore, a molecule cannot simply be treated as a "bag of atoms" during field induced ionization. In this article we present a set of experiments and theoretical calculations exploring the behavior of a large collection of aryl alkyl ketones when irradiated with intense femtosecond pulses. Specifically, we consider to what extent molecules retain their molecular identity and properties under strong laser fields. Using time-of-flight mass spectrometry in conjunction with pump-probe techniques we study the dynamical behavior of these molecules, monitoring ion yield modulation caused by intramolecular motions post ionization. The set of molecules studied is further divided into smaller sets, sorted by type and position of functional groups. The pump-probe time-delay scans show that among positional isomers the variations in relative energies, which amount to only a few hundred millielectronvolts, influence the dynamical behavior of the molecules despite their having experienced such high fields (V/Å). High level ab initio quantum chemical calculations were performed to predict molecular dynamics along with single and multiphoton resonances in the neutral and ionic states. We propose the

  3. Femtosecond spectroscopy of reacting excited states

    International Nuclear Information System (INIS)

    Thanks to recent advance of ultra short pulse lasers, we are now able to observe ultra fast phenomena taking place in a time scale as short as 10 fs. This time scale is the time scale of the nuclear motion of molecules, and the observation of coherent nuclear wavepacket motion is a central issue of femtosecond spectroscopy. One of the dreams of chemists is to see chemical reactions, i.e., the change of chemical bonds, in real time. In a sense, observation of the wavepacket motion of reacting molecules is realization of this dream. However, the significance of the coherent nuclear motion in chemical reactions is still unclear for polyatomic molecules where the reaction coordinate does not simply correspond to the change of a particular chemical bond. To discuss the relation between the initial coherent wavepacket motion and the reaction coordinate, we studied several fundamental photochemical reactions in solution, i.e., photoisomerization of cis-stilbene, photodissociation of diphenylcyclopropenone and excited-state intramolecular proton transfer of 10-hydorxybenzoquinoline, using two-color pump-probe spectroscopy with time resolution of 30-70 fs. The photoisomerization of cis-stilbene proceeds in the S1 state in a time scale of ∼1 ps. Time-resolved absorption of cis-stilbene in cyclohexane (pump 315 nm; probe 660 nm) clearly showed an oscillatory feature, which was attributed to the ∼220 cm-1 wavepacket motion in the S1 state. The dephasing time of the wavepacket motion was 0.21±0.04 ps, which was much shorter than the isomerization time of S1 cis-stilbene (1.25 ps). This indicates that a fast dephasing of the vibrational coherence takes place before isomerization. The result of the experiments on the solvent dependence demonstrated that the dephasing rate and isomerization rate do not correlate with each other, indicating that the observed wavepacket motion is not directly coupled with the isomerization coordinate. Photoexcitation to the S2 state of

  4. Ultra-fast electron diffraction using electrons accelerated by intense femtosecond laser pulses

    International Nuclear Information System (INIS)

    We have demonstrated to use electron pulses accelerated by intense femtosecond laser pulses and self-compressed for ultrafast electron diffraction (UED). The electron pulses are generated by irradiating tightly focused terawatt femtosecond laser pulses on a polyethylene foil target, then, the pulses are compressed by using an achromatic bending magnet system. These femtosecond electron pulses have an intensity to demonstrate a single-shot diffraction pattern. (author)

  5. Realignment process of actin stress fibers in single living cells studied by focused femtosecond laser irradiation

    OpenAIRE

    Yasukuni, Ryohei; Spitz, Jean-Alexis; Meallet-Renault, Rachel; Negishi, Takayuki; Tada, Takuji; Hosokawa, Yoichiroh; Asahi, Tsuyoshi; Shukunami, Chisa; Hiraki, Yuji; Masuhara, Hiroshi

    2007-01-01

    Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a...

  6. Femtosecond transient dichroism/birefringence studies of solute- solvent friction and solvent dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y.J.; Castner, E.W. Jr. [Brookhaven National Lab., Upton, NY (United States); Konitsky, W.; Waldeck, D.H. [Pittsburgh Univ., PA (United States). Dept. of Chemistry

    1994-02-01

    Ultrafast, heterodyne, polarization spectroscopies are used to measure solute-solvent frictional coupling and characterize the neat solvent`s relaxation dynamics on femtosecond and picosecond timescales.

  7. Electron dynamics in Na4 clusters under femtosecond laser irradiation

    International Nuclear Information System (INIS)

    The electron dynamics in metal clusters under femtosecond laser irradiation yield excited nonlinear phenomena under the control of laser parameters. In this study, metal clusters Na4 as an example under femtosecond laser irradiation have been observed within the framework of time-dependent density functional theory molecular dynamics (TDDFT-MD), which self-consistently couples a quantum-mechanical TDDFT treatment of valence electrons with a classical molecular dynamics description of ionic cores. The specific excitation frequencies and polarization directions of the laser have been chosen to investigate the behavior of the dipole response and ionization process. We found that it is necessary to explore the electron dynamics of metal clusters by matching the laser frequency and polarization direction. In addition, resonant dipole oscillations induced by suitable laser parameters show pronounced enhancement of the ionization behavior. (paper)

  8. Femtosecond laser fluorescence and propagation in very dense potassium vapor.

    Science.gov (United States)

    Makdisi, Y; Kokaj, J; Afrousheh, K; Nair, R; Mathew, J; Pichler, G

    2013-12-16

    Femtosecond (fs) laser propagation and fluorescence of dense potassium vapor was studied, and the spectral region around the first and the second doublets of the principal series lines of potassium atoms was investigated. In our search we did not observe the conical emission in the far field, although it was previously observed in the case of rubidium. We discuss the possible reason of this unexpected result. The fluorescence spectrum revealed Rb impurity resonance lines in emission due to the collisional redistribution from the K(4p) levels into the Rb(5p) levels. In the forward propagation of 400 nm femtosecond light we observed the molecular band red shifted from potassium second doublet. However, no molecular spectrum was observed when the mode-locked fs laser light was discretely tuned within the wings of the first resonance lines, at 770 nm. PMID:24514609

  9. Photon-Induced Borate Groups Transformation by Femtosecond Laser

    Institute of Scientific and Technical Information of China (English)

    杨晓燕; 余昺鲲; 姜雄伟; 曾慧丹

    2003-01-01

    In this paper, we put emphasis on the analysis the mechanism of the photon-induced frequency conversion β-BaB2O4 crystal inside a borate glass using femtosecond laser. Because of the nature of femtosecond laser's ultra-short pulse duration and high-energy density, in essence the laser-glass interaction mechanism is changed. Based on multiphoton ionization, collisional ionization and the network depolymerization in the borate glass, production of the plasma drives the microstructure rearrangement near the laser beam focusing area. From the structure of glass and crystal analysis, we conclude that the complicated borate groups containing BO3 and BO4 units inside the glass are converted into(B3O6)-3 anion rings.

  10. Femtosecond control of electric currents in metallic ferromagnetic heterostructures

    Science.gov (United States)

    Huisman, T. J.; Mikhaylovskiy, R. V.; Costa, J. D.; Freimuth, F.; Paz, E.; Ventura, J.; Freitas, P. P.; Blügel, S.; Mokrousov, Y.; Rasing, Th.; Kimel, A. V.

    2016-05-01

    The idea to use not only the charge but also the spin of electrons in the operation of electronic devices has led to the development of spintronics, causing a revolution in how information is stored and processed. A novel advancement would be to develop ultrafast spintronics using femtosecond laser pulses. Employing terahertz (1012 Hz) emission spectroscopy and exploiting the spin–orbit interaction, we demonstrate the optical generation of electric photocurrents in metallic ferromagnetic heterostructures at the femtosecond timescale. The direction of the photocurrent is controlled by the helicity of the circularly polarized light. These results open up new opportunities for realizing spintronics in the unprecedented terahertz regime and provide new insights in all-optical control of magnetism.

  11. Initial photochemistry of bilirubin probed by femtosecond spectroscopy.

    Science.gov (United States)

    Zietz, Burkhard; Gillbro, Tomas

    2007-10-18

    Bilirubin is a breakdown product from heme catabolism, and reduced excretion of bilirubin can lead to jaundice. Phototherapy is the most common treatment for neonatal jaundice, a condition frequently encountered in newborn infants. Knowledge of the photochemistry of bilirubin, which is dominated by (ultra)fast components, is necessary for the profound understanding of the processes in phototherapy. Here, we report results from femtosecond fluorescence upconversion measurements on bilirubin and half-bilirubin model compounds, as well as pump-probe absorption measurements on bilirubin. A fast component of ca. 120 fs in the multiexponential fluorescence decay, being only visible in the bilirubin molecule, is interpreted as exciton localization within the molecular halves. The slower components of several hundreds of femtoseconds and a few picoseconds, occurring in bilirubin and the half-bilirubin model, are interpreted as relaxation to a (twisted) intermediate, which decays further with ca. 15 ps to the ground state. PMID:17927274

  12. Beam wandering of femtosecond laser filament in air.

    Science.gov (United States)

    Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

    2015-10-01

    The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc. PMID:26480079

  13. Controllable Femtosecond Laser-Induced Dewetting for Plasmonic Applications

    CERN Document Server

    Makarov, Sergey V; Mukhin, Ivan S; Shishkin, Ivan I; Zuev, Dmitriy A; Mozharov, Alexey M; Krasnok, Alexander E; Belov, Pavel A

    2015-01-01

    Dewetting of thin metal films is one of the most widespread method for functional plasmonic nanostructures fabrication. However, simple thermal-induced dewetting does not allow to control degree of nanostructures order without additional lithographic process steps. Here we propose a novel method for lithography-free and large-scale fabrication of plasmonic nanostructures via controllable femtosecond laser-induced dewetting. The method is based on femtosecond laser surface pattering of a thin film followed by a nanoscale hydrodynamical instability, which is found to be very controllable under specific irradiation conditions. We achieve control over degree of nanostructures order by changing laser irradiation parametrs and film thickness. This allowed us to exploit the method for the broad range of applications: resonant light absorbtion and scattering, sensing, and potential improving of thin-film solar cells.

  14. [Objective evaluation the application of femtosecond laser in cataract surgery].

    Science.gov (United States)

    Liu, Y Z

    2016-02-11

    Femtosecond laser-assisted cataract surgery (FLACS) is a novel technology and the biggest revolution in the field of cataract in the latest several years. However, increasing large-scale population randomized controlled trials (RCT) have demonstrated that FLACS does not provide significant advantages over conventional phacoemulsification cataract surgery (CPCS) for common cataract patients. Furthermore, the cost and space requirement of the femtosecond equipment are another two limitations for the universal application of FSL in cataract surgery. However, FLACS may be beneficial for complex cataract situations, such as lens dislocation, zonular laxity, traumatic cataract, low preoperative endothelial cell values, and significant corneal astigmatism. With the progress of science and technology, FLACS can be expected to achieve integration with phacoemulsification systems, and equipment costs can be reduced, making it more widely used in clinical practice in the future. (Chin J Ophthalmol, 2016, 52: 81-84). PMID:26906700

  15. Femtosecond control of electric currents in metallic ferromagnetic heterostructures.

    Science.gov (United States)

    Huisman, T J; Mikhaylovskiy, R V; Costa, J D; Freimuth, F; Paz, E; Ventura, J; Freitas, P P; Blügel, S; Mokrousov, Y; Rasing, Th; Kimel, A V

    2016-05-01

    The idea to use not only the charge but also the spin of electrons in the operation of electronic devices has led to the development of spintronics, causing a revolution in how information is stored and processed. A novel advancement would be to develop ultrafast spintronics using femtosecond laser pulses. Employing terahertz (10(12) Hz) emission spectroscopy and exploiting the spin-orbit interaction, we demonstrate the optical generation of electric photocurrents in metallic ferromagnetic heterostructures at the femtosecond timescale. The direction of the photocurrent is controlled by the helicity of the circularly polarized light. These results open up new opportunities for realizing spintronics in the unprecedented terahertz regime and provide new insights in all-optical control of magnetism. PMID:26854566

  16. Ultrafast Phenomena in Solids Excited by Femtosecond Pulse

    Institute of Scientific and Technical Information of China (English)

    YUAN Dong-qing; ZHOU Ming; DAI Qi-xun; YUAN Run; LIU Hui-xia; REN Nai-fei; CHEN Lei

    2007-01-01

    The pump-probe technique is an effective instrument for investigating ultrafast dynamics. It is widely used in fundamental research and application fields, such as Physics, Chemistry and Biology. First introduced is the effect process between femtosecond laser and matter. And set forth is the fundamental of ultrafast phenomena and theory foundation of data disposal. Then introduced is the demand of making samples in experiment, experiment equipment, and the theory of strain pulse. We detect transient reflectivity change on surface of GaAs at different delayed time using femtosecond transient reflection spectroscopy. The changing curve consists of three parts: original scattering process of 100 fs, carriers-lattice thermal equilibrium of 1.5 ps and recombination process of 500 ps.

  17. Selective metallization on insulator surfaces with femtosecond laser pulses.

    Science.gov (United States)

    Xu, Jian; Liao, Yang; Zeng, Huidan; Zhou, Zenghui; Sun, Haiyi; Song, Juan; Wang, Xinshun; Cheng, Ya; Xu, Zhizhan; Sugioka, Koji; Midorikawa, Katsumi

    2007-10-01

    We report selective metallization on surfaces of insulators (glass slides and lithium niobate crystal) based on femtosecond laser modification combined with electroless plating. The process is mainly composed of four steps: (1) formation of silver nitrate thin films on the surfaces of glass or crystal substrates; (2) generation of silver particles in the irradiated area by femtosecond laser direct writing; (3) removal of unirradiated silver nitrate films; and (4) selective electroless plating in the modified area. We discuss the mechanism of selective metallization on the insulators. Moreover, we investigate the electrical and adhesive properties of the copper microstructures patterned on the insulator surfaces, showing great potential of integrating electrical functions into lab-on-a-chip devices. PMID:19550542

  18. Analysis on volume grating induced by femtosecond laser pulses.

    Science.gov (United States)

    Zhou, Keya; Guo, Zhongyi; Ding, Weiqiang; Liu, Shutian

    2010-06-21

    We report on a kind of self-assembled volume grating in silica glass induced by tightly focused femtosecond laser pulses. The formation of the volume grating is attributed to the multiple microexplosion in the transparent materials induced by the femtosecond pulses. The first order diffractive efficiency is in dependence on the energy of the pulses and the scanning velocity of the laser greatly, and reaches as high as 30%. The diffraction pattern of the fabricated grating is numerically simulated and analyzed by a two dimensional FDTD method and the Fresnel Diffraction Integral. The numerical results proved our prediction on the formation of the volume grating, which agrees well with our experiment results. PMID:20588497

  19. Femtosecond laser written embedded diffractive optical elements and their applications

    Science.gov (United States)

    Choi, Jiyeon; Ramme, Mark; Anderson, Troy; Richardson, Martin C.

    2010-02-01

    Femtosecond laser direct writing (FLDW) has been widely employed to create volumetric structures in transparent materials that are applicable as various photonic devices such as active and passive waveguides, couplers, gratings, and diffractive optical elements (DOEs). The advantages of fabrication of volumetric DOEs using FLDW include not only the ability to produce embedded 3D structures but also a simple fabrication scheme, ease of customization, and a clean process. DOE fabrication techniques using FLDW are presented as well as the characterization of laserwritten DOEs by various methods such as diffraction efficiency measurement. Fresnel zone plates were fabricated in oxide glasses using various femtosecond laser systems in high and low repetition rate regimes. The diffraction efficiency as functions of fabrication parameters was measured to investigate the dependence on the different fabrication parameters such as repetition rate and laser dose. Furthermore, several integration schemes of DOE with other photonic structures are demonstrated for compact photonic device fabrication.

  20. Fabrication of microchannels in fused silica using femtosecond Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Yashunin, D. A., E-mail: yashuninda@yandex.ru [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod 603950 (Russian Federation); Nizhny Novgorod State Technical University, 24 Minin St., Nizhny Novgorod 603950 (Russian Federation); Malkov, Yu. A. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod 603950 (Russian Federation); Mochalov, L. A.; Stepanov, A. N. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod 603950 (Russian Federation); Nizhny Novgorod State Technical University, 24 Minin St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation)

    2015-09-07

    Extended birefringent waveguiding microchannels up to 15 mm long were created inside fused silica by single-pulse irradiation with femtosecond Bessel beams. The birefringent refractive index change of 2–4 × 10{sup −4} is attributed to residual mechanical stress. The microchannels were chemically etched in KOH solution to produce 15 mm long microcapillaries with smooth walls and a high aspect ratio of 1:250. Bessel beams provide higher speed of material processing compared to conventional multipulse femtosecond laser micromachining techniques and permit simple control of the optical axis direction of the birefringent waveguides, which is important for practical applications [Corrielli et al., “Rotated waveplates in integrated waveguide optics,” Nat. Commun. 5, 4249 (2014)].

  1. Oil-free hyaluronic acid matrix for serial femtosecond crystallography

    Science.gov (United States)

    Sugahara, Michihiro; Song, Changyong; Suzuki, Mamoru; Masuda, Tetsuya; Inoue, Shigeyuki; Nakane, Takanori; Yumoto, Fumiaki; Nango, Eriko; Tanaka, Rie; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Yabashi, Makina; Nureki, Osamu; Numata, Keiji; Iwata, So

    2016-04-01

    The grease matrix was originally introduced as a microcrystal-carrier for serial femtosecond crystallography and has been expanded to applications for various types of proteins, including membrane proteins. However, the grease-based matrix has limited application for oil-sensitive proteins. Here we introduce a grease-free, water-based hyaluronic acid matrix. Applications for proteinase K and lysozyme proteins were able to produce electron density maps at 2.3-Å resolution.

  2. Oil-free hyaluronic acid matrix for serial femtosecond crystallography

    OpenAIRE

    Michihiro Sugahara; Changyong Song; Mamoru Suzuki; Tetsuya Masuda; Shigeyuki Inoue; Takanori Nakane; Fumiaki Yumoto; Eriko Nango; Rie Tanaka; Kensuke Tono; Yasumasa Joti; Takashi Kameshima; Takaki Hatsui; Makina Yabashi; Osamu Nureki

    2016-01-01

    The grease matrix was originally introduced as a microcrystal-carrier for serial femtosecond crystallography and has been expanded to applications for various types of proteins, including membrane proteins. However, the grease-based matrix has limited application for oil-sensitive proteins. Here we introduce a grease-free, water-based hyaluronic acid matrix. Applications for proteinase K and lysozyme proteins were able to produce electron density maps at 2.3-Å resolution.

  3. Femtosecond laser studies of CO and NO on Pd(111)

    OpenAIRE

    Butorac, J.

    2011-01-01

    The ultimate goal of any branch of chemistry, including surface chemistry, is to understand the dynamics of reactions. The typical time scale for bond making and breaking is the femtosecond time scale. Femtochemistry has led to enormous progress in the understanding, and even control, of chemical reactions in the gas and solution phases over the past decades. However, a comparable level of sophistication in the analysis of surface chemical reactions has not been achieved due to...

  4. Femtosecond-pulse-train ionization of Rydberg wave packets

    OpenAIRE

    Simonsen, Sigrid Ina; Sørngård, Stian Astad; Førre, Morten; Hansen, Jan Petter

    2012-01-01

    We calculate, based on first-order perturbation theory, the total and differential ionization probabilities from a dynamic periodic Rydberg wave packet of a given n-shell exposed to a train of femtosecond laser pulses. The total probability is shown to depend crucially on the laser repetition rate: For certain frequencies the ionization probability vanishes, while for others it becomes very large. The origin of this effect is the strong dependence of the ionization probability on ...

  5. New technology update: femtosecond laser in cataract surgery

    OpenAIRE

    Nagy ZZ

    2014-01-01

    Zoltan Z NagyDepartment of Ophthalmology, Semmelweis University, Budapest, HungaryAbstract: Femtosecond lasers represent a new frontier in cataract surgery. Since their ­introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented regarding c...

  6. New technology update: femtosecond laser in cataract surgery

    OpenAIRE

    Nagy, Zoltan

    2014-01-01

    Zoltan Z NagyDepartment of Ophthalmology, Semmelweis University, Budapest, HungaryAbstract: Femtosecond lasers represent a new frontier in cataract surgery. Since their ­introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented reg...

  7. Femtosecond dynamics of hydrogen elimination: benzene formation from cyclohexadiene

    OpenAIRE

    Feyter, Steven De; Diau, Eric W.-G.; Zewail, Ahmed H.

    2000-01-01

    Using femtosecond-resolved mass spectrometry in a molecular beam, we report real-time study of the hydrogen elimination reaction of 1,4-cyclohexadiene. The experimental observation of the ultrafast stepwise H-elimination elucidates the reaction dynamics and mechanism. With density-functional theory (ground-state) calculations, the nature of the reaction (multiple) pathways is examined. With the help of recent conical-intersection calculations, the excited-state and ground-state pathways are c...

  8. Femtosecond photodissociation dynamics of I studied by ion imaging

    DEFF Research Database (Denmark)

    Larsen, J.J.; Bjerre, N.; Mørkbak, N.J.;

    1998-01-01

    on imaging is employed to analyze the fragments from timed Coulomb explosion studies of femtosecond (fs) molecular dynamics. The technique provides high detection efficiency and direct recording of the two-dimensional velocity of all ionized fragments. We illustrate the approach by studying...... agreement with quantum mechanical wave packet simulations. We discuss the perspectives for extending the studies to photochemical reactions of small polyatomic molecules...

  9. Terahertz generation in an actively controlled femtosecond enhancement cavity

    International Nuclear Information System (INIS)

    We report on terahertz generation by Cherenkov-type optical rectification in lithium niobate using an actively controlled femtosecond pumped enhancement cavity. In this way a much higher pump power is available inside the cavity and an increased terahertz output power is obtained. The advantages of terahertz generation in the Cherenkov geometry are verified by comparing it with other types of emitters by means of electro-optical detection as well as by bolometer measurements

  10. Femtosecond spectroscopy on alkali-doped helium nanodroplets

    International Nuclear Information System (INIS)

    In the present thesis first studies on the short-time dynamics in alkali dimers and microclusters, which were bound on the surface of superfluid helium droplets, were presented. The experiments comprehended pump-probe measurements on the fs scale on the vibration dynamics on the dimers and on the fragmentation dynamics on the clusters. Generally by the studies it was shown that such extremely short slopes can also be observed on helium droplets by means of the femtosecond spectroscopy

  11. Patterned birefringent polarization converters fabricated by femtosecond laser direct writing

    OpenAIRE

    Gertus, T.; Kazansky, P. G.

    2014-01-01

    Under certain exposure conditions, focused femtosecond light pulses can induce self-assembled nanogratings inside bulk of fused silica glass. Orientation of nanogratings is always perpendicular to incident light polarization. Induced nanograting period varies from 140 nm to 320 nm. By changing incident light power and polarization orientation we can control induced retardance and slow axis of fabricated birefringent patterns. Induced nanogratings exhibit birefringence that provide retardance ...

  12. 10 GHz femtosecond pulse interleaver in planar waveguide technology

    OpenAIRE

    Sander, M. Y.; Frolov, S.; Shmulovich, J.; Ippen, E. P.; Kärtner, F. X.

    2012-01-01

    Coherent pulse interleaving implemented in planar waveguide technology is presented as a compact and robust solution to generate high repetition rate frequency combs. We demonstrate a 10 GHz pulse train from an Er-doped femtosecond fiber laser that is coupled into waveguide interleavers and multiplied in repetition rate by a factor of 16. With thermal tuning of the chip elements, we achieve optical and RF sidemode suppression levels of at least -30 dB.

  13. Comparison Of Photorefractive Keratectomy Versus Femtosecond Lasik For Correction Myopia

    OpenAIRE

    Salem Ali Alsalem; Ali Hassan Almordef; Zaid Mohammed Alsaqour

    2013-01-01

    This study aimed to compare and determine the differences in visual acuity, complications and higher order aberration (HOAs) in eyes with stable myopia undergoing either photorefractive keratectomy (PRK) or femtosecond Lasik (Fs Lasik) flaps were created with an intended thickness of 100 µm, diameter of 8.4 to 9.0 mm, superior hinge, at one month postoperatively. Prospective study, randomized pilot study, refractive surgery was performed on 40 eyes: 20 eyes with PRK and 20 eyes with Fs Lasik....

  14. Cluster emission under femtosecond laser ablation of silicon

    OpenAIRE

    Bulgakov, Alexander,; Ozerov, Igor; Marine, Wladimir

    2003-01-01

    Rich populations of clusters have been observed after femtosecond laser ablation of bulk silicon in vacuum. Size and velocity distributions of the clusters as well as their charge states have been analyzed by reflectron time-of-flight mass spectrometry. An efficient emission of both neutral silicon clusters Sin (up to n = 6) and their cations Sin+ (up to n = 10) has been observed. The clusters are formed even at very low laser fluences, below ablation threshold, and their relative yield incre...

  15. Analyses of femtosecond laser ablation of Ti, Zr, Hf

    OpenAIRE

    Grojo, D.; Hermann, J.; Bruneau, S; Itina, T

    2004-01-01

    Femtosecond laser ablation of Ti, Zr and Hf has been investigated by means of in-situ plasma diagnostics. Fast plasma imaging with the aid of an intensified charged coupled device (ICCD) camera was used to characterise the plasma plume expansion on a nanosecond time scale. Time- and spaceresolved optical emission spectroscopy was employed to perform time-of-flight measurements of ions and neutral atoms. It is shown that two plasma components with different expansion velocities are generated b...

  16. Direct femtosecond laser waveguide writing inside zinc phosphate glass

    OpenAIRE

    Fletcher, L.; Witcher, J.J.; Troy, N.; Reis, S.T.; Brow, R.K.; Krol, D.M.

    2011-01-01

    We report the relationship between the initial glass composition and the resulting microstructural changes after direct femtosecond laser waveguide writing with a 1 kHz repetition rate Ti:sapphire laser system. A zinc polyphosphate glass composition with an oxygen to phosphorus ratio of 3.25 has demonstrated positive refractive index changes induced inside the focal volume of a focusing microscope objective for laser pulse energies that can achieve intensities above the modification threshold...

  17. On the interferometric coherent structures in femtosecond supercontinuum generation

    Science.gov (United States)

    Dinda, Sirshendu; Bandyopadhyay, Soumendra Nath; Goswami, Debabrata

    2016-05-01

    We report structured interferometric features in femtosecond supercontinuum generation (FSG) with incident laser powers that are near threshold for FSG. We argue that near threshold, these structures arise from the coherent superposition of pulses that are split initially into two daughter pulses during FSG process. Increase in the input pulse energy generates multiple daughter fragments in the temporal domain to an extent that correlated interference structures are not measurable.

  18. Two-crystal, synchronously pumped, femtosecond optical parametric oscillator

    OpenAIRE

    Ramaiah-Badarla, V.; Esteban-Martin, A.; Ebrahim-Zadeh, Majid

    2015-01-01

    We demonstrate a femtosecond optical parametric oscillator based on two nonlinear crystals synchronously pumped by a single ultrafast laser for efficient intracavity signal amplification and output power enhancement. By deploying two identical MgO:PPLN crystals in a single standing-wave cavity, and two pump pulse trains of similar average power from the same Kerr-lens-mode-locked Ti:sapphire laser, a minimum enhancement of 56% in the extracted signal power is achieved, with un-opt...

  19. Femtosecond laser-induced microstructure in Foturan glass

    International Nuclear Information System (INIS)

    We report on the microstructure formation in Foturan glass, induced by 1 kHz, 120 femtosecond laser irradiation. It is found that the line-shaped filamentation, not void array tends to be formed in this glass. This is different from our previous experimental results in fused silica and BK7 glasses. A possible mechanism Ag+ captures the free electrons generated by laser, is proposed to explain the observed phenomena. (classical areas of phenomenology)

  20. Femtosecond laser waveguide micromachining of PMMA films with azoaromatic chromophores.

    Science.gov (United States)

    Mendonca, C R; Cerami, L R; Shih, T; Tilghman, R W; Baldacchini, T; Mazur, E

    2008-01-01

    We report on the femtosecond-laser micromachining of poly(methyl methacrylate) (PMMA) films doped with nonlinear azoaromatic chromophores: Disperse Red 1, Disperse Red 13 and Disperse Orange 3. We study the conditions for controlling chromophore degradation during the micromachining of PMMA doped with each chromophore. Furthermore, we successfully used fs-micromachining to fabricate optical waveguides within a bulk sample of PMMA doped with these azochromophores. PMID:18521148

  1. Femtosecond micromachining in transparent bulk materials using an anamorphic lens.

    Science.gov (United States)

    Desautels, G Logan; Brewer, Chris D; Walker, Mark A; Juhl, Shane B; Finet, Marc A; Powers, Peter E

    2007-10-01

    A unique anamorphic lens design was applied to a circular 780nm femtosecond laser pulse to transform it into an elliptically shaped beam at focus. This lens was developed to give an alternative method of micromachining bulk transparent materials. The challenge for femtosecond laser processing is to control the nonlinear affect of self-focusing, which can occur when using a fast f-number lens. Once the focused spot is dominated by self-focusing the predicted focused beam becomes a filament inside the bulk, which is an undesirable effect. The anamorphic lens resolves this self-focusing by increasing the numerical aperture (NA) and employing an elliptical beam shape. The anamorphic lens was designed to furnish a 2.5mum by 190mum line at focus. Provided the pulse energy is high enough, transparent bulk material will be damaged with a single femtosecond laser pulse. Damage in this text refers to visual change in the index of refraction as observed under an optical microscope. Using this elliptical shape (or line), grating structures were micro-machined on the surface of SiC bulk transparent substrate. SiC was chosen because it is known for its micromachining difficulty and its crystalline structure. From the lack of self-focusing and using energy that is just above the damage threshold the focused line beam generated from the anamorphic lens grating structures produced a line shape nearly identical to the geometrical approximation. In this paper we discuss a new method of writing gratings (or other types of structures) in bulk transparent materials using a single femtosecond laser pulse. We will investigate the grating structures visually (inspected under an optical microscope) and also by use of an atomic force microscopy (AFM). In addition, we test the grating diffraction efficiency (DE) as a function of grating spacing, d. PMID:19550582

  2. A compact femtosecond Ti: sapphire/KrF laser system

    International Nuclear Information System (INIS)

    A compact femtosecond Ti:sapphire/KrF laser system which produces ultraviolet and ultrashort pulse has been developed. It consists of a mode-locked Ti:Sapphire laser, a regenerative amplifier, a frequency conversion system and a KrF excimer amplifier. The system can produce 50 mJ of pulse energy at a pulse width of 440 fs. The pulse width can be reduced down to 100 fs region using a prism pair compressor. (author)

  3. Deuterium Clusters Fusion Induced by the Intense Femtosecond Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-Jie; CHEN Jia-Bin; WANG Hong-Bin; JIAO Chun-Ye; HE Ying-Ling; WEN Tian-Shu; WEN Xian-Lun; CHEN Ming; ZHENG Zhi-Jian; GU Yu-Qiu; ZHANG Bao-Han; RHEE Yong-Joo; NAM Sung-Mo; HAN Jae-Min; RHEE Yong-Woo; YEA Kwon-Hae

    2007-01-01

    Neutrons (2.45 MeV) from deuterium cluster fusion induced by the intense femtosecond (30 fs) laser pulse are experimentally demonstrated. The average neutron yield 103 per shot is obtained. It is found that the yield slightly increases with the increasing laser spot size. No neutron can be observed when the laser intensity Ⅰ <4.3×1015 W/cm2.

  4. Single shot depth sensitivity using femtosecond Laser Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

    Depth profiling measurement using multiple pulse Laser Induced Breakdown Spectroscopy (LIBS) can be used to determine the characteristics of buried layers. However for femtosecond pulses the emission spectra does not necessarily reflect the average depth composition for the single shot case and instead has much higher sensitivity for the surface layer of the ablation region. We introduce a concept of “depth sensitivity” to characterize this behavior for single shot LIBS depth profiling. Experiments were carried out using 800 nm femtosecond laser pulses irradiating layered targets while monitoring the plasma emission with a spectrometer system. Laser induced plasma formed at the surface layer exhibits a strong LIBS signature while deeper ablated region contributes very little to the emission spectrum. The sensitive depth region, the source of the major part of the emission, is much less than the ablation crater depth and is shown to be of the order of 3 nm in the case of actual crater depths of 100's of nm. A two temperature model has been used to determine the lattice temperature profile versus depth which qualitatively predicts the observed behavior. - Highlights: • Depth dependence of LIBS emission within a single 800 nm femtosecond laser shot. • LIBS emission spectra dominated by only a thin surface layer. • Depth sensitivity, a new concept, is ∼3 nm when actual crater depth ∼100’s of nm. • Qualitative agreement with TTM model of lattice temperature versus depth and time

  5. Femtosecond laser direct writing of monocrystalline hexagonal silver prisms

    International Nuclear Information System (INIS)

    Bottom-up growth methods and top-down patterning techniques are both used to fabricate metal nanostructures, each with a distinct advantage: One creates crystalline structures and the other offers precise positioning. Here, we present a technique that localizes the growth of metal crystals to the focal volume of a laser beam, combining advantages from both approaches. We report the fabrication of silver nanoprisms—hexagonal nanoscale silver crystals—through irradiation with focused femtosecond laser pulses. The growth of these nanoprisms is due to a nonlinear optical interaction between femtosecond laser pulses and a polyvinylpyrrolidone film doped with silver nitrate. The hexagonal nanoprisms have bases hundreds of nanometers in size and the crystal growth occurs over exposure times of less than 1 ms (8 orders of magnitude faster than traditional chemical techniques). Electron backscatter diffraction analysis shows that the hexagonal nanoprisms are monocrystalline. The fabrication method combines advantages from both wet chemistry and femtosecond laser direct-writing to grow silver crystals in targeted locations. The results presented in this letter offer an approach to directly positioning and growing silver crystals on a substrate, which can be used for plasmonic devices.

  6. Femtosecond magnetooptics and ultrafast magnetization reversal of ferromagnetic

    International Nuclear Information System (INIS)

    The model of ultrafast magnetic dynamics to describe the magnetization switching of ferromagnetics after the action of femtosecond laser pulses is proposed. The model suggests that processes of femtosecond duration are the property of orbital rather than spin magnetism. This assumption is shown not to contradict with the existing theoretical and experimental data. The equations for the description of the optical excitation of electrons in the Bloch model of ultrafast orbital dynamics in the electric dipole approximation are obtained. They have type of Bloch equations for the artificial vector. Its two components correspond to the electric polarization created by the electric field of the light wave. The third component is expressed through the orbital angular momentum of electrons. The analysis of solutions of these equations yielded the conditions under which the optical pump leaves non-equilibrium electron orbital angular momenta. The possibility of spin switching in the spin orbital field of nonequilibrium orbital momenta is discussed. - Highlights: • The ultrafast magnetic dynamics is caused by orbital rather than spin magnetism. • Action of femtosecond laser pump changes orbital electron state rather than spin one. • Optical excitation of electrons can be described by the equation for special vector V. • The vector V is composed of the electrical and orbital magnetic momenta of electrons. • The proposed model does not require a revision of the existing spin theory

  7. Femtosecond Pump-Probe Microspectroscopy of Single Perylene Nanoparticles.

    Science.gov (United States)

    Ishibashi, Yukihide; Asahi, Tsuyoshi

    2016-08-01

    We have developed a femtosecond pump-probe light scattering microspectroscopic system in which the output of a femtosecond Ti:sapphire oscillator (1 W, 82 MHz) was used as a light source; the pump light is the second harmonics (395 nm) of the laser output, and the probe light is a femtosecond white-light continuum (490-900 nm) generated with a photonic crystal fiber. Detection of the backscattered light from single nanoparticle on a glass substrate allowed us to obtain higher gain of the transient signals by ∼20 times in comparison with the conventional transmittance-mode experiment. This high-sensitivity of the backscattering detection makes it possible to examine ultrafast relaxation dynamics of excited states in organic nanoparticles, which, in general, are lower photodurability than the inorganic one. We applied the system to single nanocrystals of α-form perylene and then succeeded in direct observation of the excimer formation dynamics on a picosecond time scale. Single nanoparticle measurements for the perylene nanocrystals having a size range of 100 to 500 nm suggested that the excimer formation time became short from 2 ps to <0.3 ps for decreasing of the size. PMID:27420175

  8. Measurement and timing-control techniques of femtosecond electron pulse

    International Nuclear Information System (INIS)

    Updated techniques and results on the measurement and timing-control of femtosecond electron pulses are presented. Radiation emitted by an electron pulse was measured by a femtosecond streak camera, a Michelson interferometer, a 10-channel polychromator and a fluctuation method in order to estimate a longitudinal pulse shape of the electron pulse. Measurements by the streak camera, the interferometer and the polychromator agree with one another within the error of 20%, while that by the fluctuation method was different. The numerical simulation explained the reason for it that the transverse emittance of the electron pulse affects the fluctuation of incoherent Cherenkov radiation. The synchronization of the electron pulse with the femtosecond laser pulse was also carried out. The timing jitter was 330 fs in rms and the hours-long drift was more than 1 ps. The suppression of the drift is under way by introducing a stable water cooler (within 0.01 deg. C) for the accelerator tubes and RF gun, and an air-conditioner (within 2 deg. C)

  9. A new approach to fabricate pdms structures using femtosecond laser

    Science.gov (United States)

    Selvaraj, Hamsapriya

    Polydimethylsiloxane (PDMS) is commonly used to prototype micro and nano featured components due to its beneficial properties. PDMS based devices have been used for diverse applications such as cell culturing, cell sorting and sensors. Motivated by such diverse applications possible through pure PDMS and reinforced PDMS, numerous efforts have been directed towards developing novel fabrication techniques. Prototyping 2D and 3D pure and reinforced PDMS microdevices normally require a long curing time and must go through multiple steps. This research explores the possibility of fabricating microscale and nanoscale structures directly from PDMS resin using femtosecond laser processing. This study offers an alternative fabrication route that potentially lead to a new way for prototyping of pure and reinforced PDMS devices, and the generation of hybrid nanomaterials. In depth investigation of femtosecond laser irradiation of PDMS resin reveals that the process is highly intensity-dependent. At low to intermediate intensity regime, femtosecond laser beam is able to rapidly cure the resin and create micron-sized structures directly from PDMS resin. At higher intensity regime, a total break-down of the resin material occurs and leads to the formation of PDMS nanoparticles. This work demonstrates a new way of rapid curing of PDMS resin on a microsecond timescale using femtosecond laser irradiation. The proposed technique permits maskless singlestep curing and is capable of fabricating 2D and 3D structures in micro-scale. Reinforced PDMS microstructures also have been fabricated through this method. The proposed technique permits both reinforcement and rapid curing and is ideal for fabricating reinforced structures in microscale. The strength of the nanofiber reinforced PDMS microstructures has been investigated by means of Nanoindentation test. The results showed significant improvement in strength of the material. Hybrid PDMS-Si and hybrid PDMS-Al nanoparticle aggregate

  10. Fairy Lights in Femtoseconds: Aerial and Volumetric Graphics Rendered by Focused Femtosecond Laser Combined with Computational Holographic Fields

    CERN Document Server

    Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun; Hasegawa, Satoshi; Hayasaki, Yoshio

    2015-01-01

    We present a method of rendering aerial and volumetric graphics using femtosecond lasers. A high-intensity laser excites a physical matter to emit light at an arbitrary 3D position. Popular applications can then be explored especially since plasma induced by a femtosecond laser is safer than that generated by a nanosecond laser. There are two methods of rendering graphics with a femtosecond laser in air: Producing holograms using spatial light modulation technology, and scanning of a laser beam by a galvano mirror. The holograms and workspace of the system proposed here occupy a volume of up to 1 cm^3; however, this size is scalable depending on the optical devices and their setup. This paper provides details of the principles, system setup, and experimental evaluation, and discussions on scalability, design space, and applications of this system. We tested two laser sources: an adjustable (30-100 fs) laser which projects up to 1,000 pulses per second at energy up to 7 mJ per pulse, and a 269-fs laser which p...

  11. Towards using molecular ions as qubits: Femtosecond control of molecular fragmentation with multiple knobs

    Indian Academy of Sciences (India)

    Tapas Goswami; Dipak K Das; Debabrata Goswami

    2010-12-01

    Non-resonant molecular fragmentation of n-propyl benzene with femtosecond laser pulses is dependent on the phase and polarization characteristics of the laser. We find that the effect of the chirp and polarization of the femtosecond pulse when applied simultaneously is mutually independent of each other, which makes chirp and polarization as useful ‘logic’ implementing knobs.

  12. Nonlinear femtosecond laser processing of alkylsiloxane monolayers on surface-oxidized silicon substrates

    International Nuclear Information System (INIS)

    Femtosecond laser patterning of octadecylsiloxane monolayers on surface-oxidized silicon substrates via single-pulse processing at λ=800 nm, τ2. A significantly larger parameter range for selective processing is anticipated in the case of functional monolayers that incorporate aromatic groups. Promising perspectives in femtosecond laser processing of organic monolayers are discussed.

  13. Mécanismes fondamentaux de l'ablation laser femtoseconde en "flux intermédiaire"

    OpenAIRE

    Petite, Guillaume

    2005-01-01

    This chapter aims at identifying what is specific to femtosecond laser ablation. It reviews the essential basic processes which contribute to femtosecond laser ablation of various materials : energy absorption by the material's electrons, electronic relaxation processes involving either electron-electron or electron-lattice interactions. A number of widely used models are briefly discussed, as well as some pending questions.

  14. Femtosecond Transversal Deflection of Electron Beams with the Help of Laser Beams and Its Possible Applications

    OpenAIRE

    Ispirian, K. A.; Ispiryan, M. K.

    2003-01-01

    It is shown that the interaction of an electron beam with polarized electromagnetic wave of laser photons propagating in the same direction in a short interaction region results in significant transversal deflection of the electrons which can be used for production of femtosecond electron and synchrotron radiation beams, for chopping the electron beams and construction of laser oscilloscopes measuring femtosecond processes.

  15. Femtosecond laser micromachining for the realization of fully integrated photonic and microfluidic devices

    Science.gov (United States)

    Eaton, S. M.; Osellame, R.; Ramponi, R.

    2015-02-01

    Femtosecond laser microprocessing is a direct, maskless fabrication technique that has attracted much attention in the past 10 years due to its unprecedented versatility in the 3D patterning of transparent materials. Two common modalities of femtosecond laser microfabrication include buried optical waveguide writing and surface laser ablation, which have been applied to a wide range of transparent substrates including glasses, polymers and crystals. In two photon polymerization, a third modality of femtosecond laser fabrication, focused femtosecond laser pulses drive photopolymerization in photoresists, enabling the writing of complex 3D structures with submicrometer resolution. In this paper, we discuss several microdevices realized by these diverse modalities of femtosecond laser microfabrication, for applications in microfluidics, sensing and quantum information.

  16. Development of a new picosecond pulse radiolysis system by using a femtosecond laser synchronized with a picosecond linac. A step to femtosecond pulse radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Yoichi; Yamamoto, Tamotsu; Miki, Miyako; Seki, Shu; Okuda, Shuichi; Honda, Yoshihide; Kimura, Norio; Tagawa, Seiichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Ushida, Kiminori

    1997-03-01

    A new picosecond pulse radiolysis system by using a Ti sapphire femtosecond laser synchronized with a 20 ps electron pulse from the 38 MeV L-band linac has been developed for the research of the ultra fast reactions in primary processes of radiation chemistry. The timing jitter in the synchronization of the laser pulse with the electron pulse is less than several picosecond. The technique can be used in the next femtosecond pulse radiolysis. (author)

  17. Femtosecond pulsed laser deposition of biological and biocompatible thin layers

    Energy Technology Data Exchange (ETDEWEB)

    Hopp, B. [Hungarian Academy of Sciences, University of Szeged, Research Group on Laser Physics, Dom ter 9, H-6720 Szeged (Hungary)]. E-mail: bhopp@physx.u-szeged.hu; Smausz, T. [Hungarian Academy of Sciences, University of Szeged, Research Group on Laser Physics, Dom ter 9, H-6720 Szeged (Hungary); Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Klini, A. [Institute of Electronic Structure and Laser (I.E.S.L.), Foundation for Research and Technology-Hellas (F.O.R.T.H.), P.O. Box 1527, GR-711 10 Heraklion, Crete (Greece); Bor, Zs. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary)

    2007-07-31

    In our study we investigate and report the femtosecond pulsed laser deposition of biological and biocompatible materials. Teflon, polyhydroxybutyrate, polyglycolic-acid, pepsin and tooth in the form of pressed pellets were used as target materials. Thin layers were deposited using pulses from a femtosecond KrF excimer laser system (FWHM = 450 fs, {lambda} = 248 nm, f = 10 Hz) at different fluences: 0.6, 0.9, 1.6, 2.2, 2.8 and 3.5 J/cm{sup 2}, respectively. Potassium bromide were used as substrates for diagnostic measurements of the films on a FTIR spectrometer. The pressure in the PLD chamber was 1 x 10{sup -3} Pa, and in the case of tooth and Teflon the substrates were heated at 250 deg. C. Under the optimized conditions the chemical structure of the deposited materials seemed to be largely preserved as evidenced by the corresponding IR spectra. The polyglycolic-acid films showed new spectral features indicating considerable morphological changes during PLD. Surface structure and thickness of the layers deposited on Si substrates were examined by an atomic force microscopy (AFM) and a surface profilometer. An empirical model has been elaborated for the description of the femtosecond PLD process. According to this the laser photons are absorbed in the surface layer of target resulting in chemical dissociation of molecules. The fast decomposition causes explosion-like gas expansion generating recoil forces which can tear off and accelerate solid particles. These grains containing target molecules without any chemical damages are ejected from the target and deposited onto the substrate forming a thin layer.

  18. Femtosecond X-ray scattering in condensed matter

    International Nuclear Information System (INIS)

    This thesis investigates the manifold couplings between electronic and structural properties in crystalline Perovskite oxides and a polar molecular crystal. Ultrashort optical excitation changes the electronic structure and the dynamics of the connected reversible lattice rearrangement is imaged in real time by femtosecond X-ray scattering experiments. An epitaxially grown superlattice consisting of alternating nanolayers of metallic and ferromagnetic strontium ruthenate (SRO) and dielectric strontium titanate serves as a model system to study optically generated stress. In the ferromagnetic phase, phonon-mediated and magnetostrictive stress in SRO display similar sub-picosecond dynamics, similar strengths but opposite sign and different excitation spectra. The amplitude of the magnetic component follows the temperature dependent magnetization square, whereas the strength of phononic stress is determined by the amount of deposited energy only. The ultrafast, phonon-mediated stress in SRO compresses ferroelectric nanolayers of lead zirconate titanate in a further superlattice system. This change of tetragonal distortion of the ferroelectric layer reaches up to 2 percent within 1.5 picoseconds and couples to the ferroelectric soft mode, or ion displacement within the unit cell. As a result, the macroscopic polarization is reduced by up to 100 percent with a 500 femtosecond delay that is due to final elongation time of the two anharmonically coupled modes. Femtosecond photoexcitation of organic chromophores in a molecular, polar crystal induces strong changes of the electronic dipole moment via intramolecular charge transfer. Ultrafast changes of transmitted X-ray intensity evidence an angular rotation of molecules around excited dipoles following the 10 picosecond kinetics of the charge transfer reaction. Transient X-ray scattering is governed by solvation, masking changes of the chromophore's molecular structure. (orig.)

  19. Femtosecond X-ray scattering in condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Korff Schmising, Clemens von

    2008-11-24

    This thesis investigates the manifold couplings between electronic and structural properties in crystalline Perovskite oxides and a polar molecular crystal. Ultrashort optical excitation changes the electronic structure and the dynamics of the connected reversible lattice rearrangement is imaged in real time by femtosecond X-ray scattering experiments. An epitaxially grown superlattice consisting of alternating nanolayers of metallic and ferromagnetic strontium ruthenate (SRO) and dielectric strontium titanate serves as a model system to study optically generated stress. In the ferromagnetic phase, phonon-mediated and magnetostrictive stress in SRO display similar sub-picosecond dynamics, similar strengths but opposite sign and different excitation spectra. The amplitude of the magnetic component follows the temperature dependent magnetization square, whereas the strength of phononic stress is determined by the amount of deposited energy only. The ultrafast, phonon-mediated stress in SRO compresses ferroelectric nanolayers of lead zirconate titanate in a further superlattice system. This change of tetragonal distortion of the ferroelectric layer reaches up to 2 percent within 1.5 picoseconds and couples to the ferroelectric soft mode, or ion displacement within the unit cell. As a result, the macroscopic polarization is reduced by up to 100 percent with a 500 femtosecond delay that is due to final elongation time of the two anharmonically coupled modes. Femtosecond photoexcitation of organic chromophores in a molecular, polar crystal induces strong changes of the electronic dipole moment via intramolecular charge transfer. Ultrafast changes of transmitted X-ray intensity evidence an angular rotation of molecules around excited dipoles following the 10 picosecond kinetics of the charge transfer reaction. Transient X-ray scattering is governed by solvation, masking changes of the chromophore's molecular structure. (orig.)

  20. Widely tunable femtosecond solitonic radiation in photonic crystal fiber cladding

    DEFF Research Database (Denmark)

    Peng, J. H.; Sokolov, A. V.; Benabid, F.;

    2010-01-01

    We report on a means to generate tunable ultrashort optical pulses. We demonstrate that dispersive waves generated by solitons within the small-core features of a photonic crystal fiber cladding can be used to obtain femtosecond pulses tunable over an octave-wide spectral range. The generation...... process is highly efficient and occurs at the relatively low laser powers available from a simple Ti:sapphire laser oscillator. The described phenomenon is general and will play an important role in other systems where solitons are known to exist....

  1. Pulse front tilt measurement of femtosecond laser pulses

    Science.gov (United States)

    Dimitrov, Nikolay; Stoyanov, Lyubomir; Stefanov, Ivan; Dreischuh, Alexander; Hansinger, Peter; Paulus, Gerhard G.

    2016-07-01

    In this work we report experimental investigations of an intentionally introduced pulse front tilt on femtosecond laser pulses by using an inverted field correlator/interferometer. A reliable criterion for the precision in aligning (in principle) dispersionless systems for manipulating ultrashort pulses is developed, specifically including cases when the pulse front tilt is a result of a desired spatio-temporal coupling. The results obtained using two low-dispersion diffraction gratings are in good qualitative agreement with the data from a previously developed analytical model and from an independent interferometric measurement.

  2. Postoperative Endophthalmitis Caused by Staphylococcus haemolyticus following Femtosecond Cataract Surgery

    OpenAIRE

    Wong, Margaret; Baumrind, Benjamin R.; Frank, James H.; Halpern, Robert L.

    2015-01-01

    A 53-year-old Caucasian man underwent femtosecond cataract surgery and then presented with pain and hand motions vision 1 day following surgery. Anterior segment examination showed a 2-mm-layered hypopyon, a well-centered intraocular lens in the sulcus, and an obscured view to the fundus. B-scan ultrasonography showed significant vitritis and that the retina was attached. A tap and an injection of vancomycin 1 mg per 0.1 ml and of ceftazidime 2.25 mg per 0.1 ml were performed. The tap eventua...

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

    Science.gov (United States)

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

    2015-06-01

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

  4. Testing of a femtosecond pulse laser in outer space

    OpenAIRE

    Joohyung Lee; Keunwoo Lee; Yoon-Soo Jang; Heesuk Jang; Seongheum Han; Sang-Hyun Lee; Kyung-In Kang; Chul-Woo Lim; Young-Jin Kim; Seung-Woo Kim

    2014-01-01

    We report a test operation of an Er-doped fibre femtosecond laser which was conducted for the first time in outer space. The fibre-based ultrashort pulse laser payload was designed to meet space-use requirements, undergone through ground qualification tests and finally launched into a low-earth orbit early in 2013. Test results obtained during a one-year mission lifetime confirmed stable mode-locking all the way through although the radiation induced attenuation (RIA) in the Er-doped gain fib...

  5. Spatially-uniform temporal recompression of intense femtosecond optical pulses

    International Nuclear Information System (INIS)

    A specially designed telescope with defocusing lens and off-axis parabolic mirror, which is working as a nonlinear element and producing self-phase modulation, was implemented for intense (3.1 TW/cm2) Fourier Transform Limit femtosecond laser pulses with Gaussian beam profiles. The pulse spectrum was broadened quasi-homogeneously over the beam cross-section due to the change in the lens thickness compensating for the reduction of the beam intensity from its center to periphery. In experimental demonstrations a set of chirped mirrors allowed for the spectral phase correction to a final pulse compression of 20 fs from 40 fs. (authors)

  6. Femtosecond laser ablation of Au film around single pulse threshold

    Institute of Scientific and Technical Information of China (English)

    Xiaochang Ni; Ching-Yue Wang; Yinzhong Wu; Li Yang; Wei Jia; Lu Chai

    2006-01-01

    @@ Ablation process of 1-kHz femtosecond lasers (pulse duration of 148 fs, wavelength of 775 nm) of Au film on silica substrates is studied. The thresholds for single and multi pulses can be obtained directly from the relation between the squared diameter D2 of the ablated craters and the laser fluence φo. From the plot of the accumulated laser fluence Nφth(N) and the number of laser pulses N, incubation coefficient of Au film is obtained to be 0.765. Some experimental data obtained around the single pulse threshold are in good agreement with the theoretical calculation.

  7. Thermal character in organic polymers with nanojoule femtosecond laser ablation

    Institute of Scientific and Technical Information of China (English)

    Xiaochang Ni(倪晓昌); Ching-Yue Wang(王清月); Yanfeng Li(栗岩峰); Minglie Hu(胡明列); Zhuan Wang(王专); Lu Chai(柴路)

    2003-01-01

    Ablation experiments with femtosecond (fs) laser pulse (pulse duration 37 fs, wavelength 800 nm) on organic polymers have been performed in air. The ablation threshold is found to be only several nanojoules. The diameters of the dots ablated in the organic polymers are influenced by the laser fluence and the number of laser pulses. It is observed that heat is diffused in a threadlike manner in all directions around the central focus region. Explanations of the observed phenomena are presented. A one-dimensional waveguide is also ablated in the organic polymers.

  8. Polarization behaviour of femtosecond laser written waveguides in lithium niobate

    Science.gov (United States)

    Tejerina, M. R.; Biasetti, D. A.; Torchia, G. A.

    2015-09-01

    In this work, we analysed the polarization of guided light in femtosecond laser written waveguides. The studied waveguides were performed with different laser pulse energies in an x-cut lithium niobate crystal. The guided intensities were experimentally measured and compared with numerical simulations reaching a qualitatively good accordance. This comparison allowed a verification of the "mechanical expansion theory" which is useful to compute the refractive index field. Also, information related to the modelling of waveguides generated with different laser pulse energies was obtained. Both of these facts are keys to design and manufacture optical circuits by using this technological approach.

  9. Vibrationally-induced electronic population inversion with strong femtosecond pulses

    CERN Document Server

    Sampedro, Pablo; Sola, Ignacio R

    2016-01-01

    We discover a new mechanism of electronic population inversion using strong femtosecond pulses, where the transfer is mediated by vibrational motion on a light-induced potential. The process can be achieved with a single pulse tuning its frequency to the red of the Franck-Condon window. We show the determinant role that the sign of the slope of the transition dipole moment can play on the dynamics, and extend the method to multiphoton processes with odd number of pulses. As an example, we show how the scheme can be applied to population inversion in Na2.

  10. Focal spot of femtosecond laser pulse under tight focusing condition

    Czech Academy of Sciences Publication Activity Database

    Jeong, Tae Moon; Weber, Stefan A.; Le Garrec, Bruno; Margarone, Daniele; Mocek, Tomáš; Korn, Georg

    Bellingham: SPIE, 2015 - (Korn, G.; Silva, L.), "95150I-1"-"95150I-6". (Proceedings of SPIE. 9515). ISBN 978-1-62841-636-7. ISSN 0277-786X. [Research Using Extreme Light - Entering New Frontiers with Petawatt-Class Lasers II. Praha (CZ), 13.04.2015-15.04.2015] R&D Projects: GA MŠk ED1.1.00/02.0061 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 Keywords : femtosecond * high-power laser * relativistic * focal spot Subject RIV: BL - Plasma and Gas Discharge Physics

  11. Femtosecond pulse amplification in cladding-pumped fibers

    OpenAIRE

    Minelly, J. D.; Galvanauskas, A.; Fermann, M. E.; Harter, D.; Caplen, J.E.; Chen, Z.J.; Payne, D. N.

    1995-01-01

    Femtosecond pulse amplification in a cladding-pumped fiber amplifier is demonstrated for the first time to our knowledge. Using a cladding-pumped erbium-doped fiber power amplifier and a passively mode-locked fiber seed oscillator in conjunction with an all-fiber chirped-pulse amplification system, we obtain 380-fs near-bandwidth-limited pulses with an average power of 260 mW. The pulse repetition rate is varied between 5 and 50 MHz, and pulse energies as high as 20 nJ are generated.

  12. Femtosecond laser pulse train interaction with dielectric materials

    CERN Document Server

    Caulier, O Dematteo; Chimier, B; Skupin, S; Bourgeade, A; Léger, C Javaux; Kling, R; Hönninger, C; Lopez, J; Tikhonchuk, V; Duchateau, G

    2015-01-01

    We investigate the interaction of trains of femtosecond microjoule laser pulses with dielectric materials by means of a multi-scale model. Our theoretical predictions are directly confronted with experimental observations in soda-lime glass. We show that due to the low heat conductivity, a significant fraction of the laser energy can be accumulated in the absorption region. Depending on the pulse repetition rate, the material can be heated to high temperatures even though the single pulse energy is too low to induce a significant material modification. Regions heated above the glass transition temperature in our simulations correspond very well to zones of permanent material modifications observed in the experiments.

  13. Ocular safety limits for 1030nm femtosecond laser cataract surgery

    Science.gov (United States)

    Wang, Jenny; Sramek, Christopher; Paulus, Yannis M.; Lavinsky, Daniel; Schuele, Georg; Anderson, Dan; Dewey, David; Palanker, Daniel V.

    2013-03-01

    Application of femtosecond lasers to cataract surgery has added unprecedented precision and reproducibility but ocular safety limits for the procedure are not well-quantified. We present an analysis of safety during laser cataract surgery considering scanned patterns, reduced blood perfusion, and light scattering on residual bubbles formed during laser cutting. Experimental results for continuous-wave 1030 nm irradiation of the retina in rabbits are used to calibrate damage threshold temperatures and perfusion rate for our computational model of ocular heating. Using conservative estimates for each safety factor, we compute the limits of the laser settings for cataract surgery that optimize procedure speed within the limits of retinal safety.

  14. Protein crystal screening and characterization for serial femtosecond nanocrystallography

    Science.gov (United States)

    Darmanin, Connie; Strachan, Jamie; Adda, Christopher G.; Ve, Thomas; Kobe, Bostjan; Abbey, Brian

    2016-01-01

    The recent development of X-ray free electron lasers (XFELs) has spurred the development of serial femtosecond nanocrystallography (SFX) which, for the first time, is enabling structure retrieval from sub-micron protein crystals. Although there are already a growing number of structures published using SFX, the technology is still very new and presents a number of unique challenges as well as opportunities for structural biologists. One of the biggest barriers to the success of SFX experiments is the preparation and selection of suitable protein crystal samples. Here we outline a protocol for preparing and screening for suitable XFEL targets. PMID:27139248

  15. All-fiber femtosecond Cherenkov laser at visible wavelengths

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe Visbech;

    2013-01-01

    -matching condition [1]. The resonant ultrafast wave conversion via the fiber-optic CR mechanism is instrumental for applications in biophotonics such as bio-imaging and microscopy [2]. In this work, we demonstrate a highly-stable all-fiber, fully monolithic CR system based on an Yb-fiber femtosecond laser, producing...... conversion [5]. Bridge fibers are used in the CR link to enhance the conversion efficiency. Fig. 1(b) shows the far-field saturated visible images of the CR emitted from the laser system, generated as the pump power increases in the range 150 mW - 300 mW. The emitted CR spectra corresponding to different...

  16. Femtosecond laser for glaucoma treatment: the comparison between simulation and experimentation results on ocular tissue removal

    Science.gov (United States)

    Hou, Dong Xia; Ngoi, Bryan K. A.; Hoh, Sek Tien; Koh, Lee Huat K.; Deng, Yuan Zi

    2005-04-01

    In ophthalmology, the use of femtosecond lasers is receiving more attention than ever due to its extremely high intensity and ultra short pulse duration. It opens the highly beneficial possibilities for minimized side effects during surgery process, and one of the specific areas is laser surgery in glaucoma treatment. However, the sophisticated femtosecond laser-ocular tissue interaction mechanism hampers the clinical application of femtosecond laser to treat glaucoma. The potential contribution in this work lies in the fact, that this is the first time a modified moving breakdown theory is applied, which is appropriate for femtosecond time scale, to analyze femtosecond laser-ocular tissue interaction mechanism. Based on this theory, energy deposition and corresponding thermal increase are studied by both simulation and experimentation. A simulation model was developed using Matlab software, and the simulation result was validated through in-vitro laser-tissue interaction experiment using pig iris. By comparing the theoretical and experimental results, it is shown that femtosecond laser can obtain determined ocular tissue removal, and the thermal damage is evidently reduced. This result provides a promising potential for femtosecond laser in glaucoma treatment.

  17. Fabrication of optical cavities with femtosecond laser pulses

    Science.gov (United States)

    Lin, Jintian; Song, Jiangxin; Tang, Jialei; Fang, Wei; Sugioka, Koji; Cheng, Ya

    2014-03-01

    We report on fabrication of three-dimensional (3D) high-quality (Q) whispering-gallery-mode microcavities by femtosecond laser micromachining. The main fabrication procedures include the formation of on-chip freestanding microdisk through selective material removal by femtosecond laser pulses, followed by surface smoothing processes (CO2 laser reflow for amorphous glass and focused ion beam (FIB) sidewall milling for crystalline materials) to improve the Q factors. Fused silica microcavities with 3D geometries are demonstrated with Q factors exceeding 106. A microcavity laser based on Nd:glass has been fabricated, showing a threshold as low as 69μW via free space continuous-wave optical excitation at the room temperature. CaF2 crystalline microcavities with Q factor of ~4.2×104 have also been demonstrated. This technique allows us to fabricate 3D high-Q microcavities in various transparent materials such as glass and crystals, which will benefit a broad spectrum of applications such as nonlinear optics, quantum optics, and bio-sensing.

  18. A novel inert crystal delivery medium for serial femtosecond crystallography.

    Science.gov (United States)

    Conrad, Chelsie E; Basu, Shibom; James, Daniel; Wang, Dingjie; Schaffer, Alexander; Roy-Chowdhury, Shatabdi; Zatsepin, Nadia A; Aquila, Andrew; Coe, Jesse; Gati, Cornelius; Hunter, Mark S; Koglin, Jason E; Kupitz, Christopher; Nelson, Garrett; Subramanian, Ganesh; White, Thomas A; Zhao, Yun; Zook, James; Boutet, Sébastien; Cherezov, Vadim; Spence, John C H; Fromme, Raimund; Weierstall, Uwe; Fromme, Petra

    2015-07-01

    Serial femtosecond crystallography (SFX) has opened a new era in crystallo-graphy by permitting nearly damage-free, room-temperature structure determination of challenging proteins such as membrane proteins. In SFX, femtosecond X-ray free-electron laser pulses produce diffraction snapshots from nanocrystals and microcrystals delivered in a liquid jet, which leads to high protein consumption. A slow-moving stream of agarose has been developed as a new crystal delivery medium for SFX. It has low background scattering, is compatible with both soluble and membrane proteins, and can deliver the protein crystals at a wide range of temperatures down to 4°C. Using this crystal-laden agarose stream, the structure of a multi-subunit complex, phycocyanin, was solved to 2.5 Å resolution using 300 µg of microcrystals embedded into the agarose medium post-crystallization. The agarose delivery method reduces protein consumption by at least 100-fold and has the potential to be used for a diverse population of proteins, including membrane protein complexes. PMID:26177184

  19. Femtosecond laser ablation of gold interdigitated electrodes for electronic tongues

    Science.gov (United States)

    Manzoli, Alexandra; de Almeida, Gustavo F. B.; Filho, José A.; Mattoso, Luiz H. C.; Riul, Antonio; Mendonca, Cleber R.; Correa, Daniel S.

    2015-06-01

    Electronic tongue (e-tongue) sensors based on impedance spectroscopy have emerged as a potential technology to evaluate the quality and chemical composition of food, beverages, and pharmaceuticals. E-tongues usually employ transducers based on metal interdigitated electrodes (IDEs) coated with a thin layer of an active material, which is capable of interacting chemically with several types of analytes. IDEs are usually produced by photolithographic methods, which are time-consuming and costly, therefore, new fabrication technologies are required to make it more affordable. Here, we employed femtosecond laser ablation with pulse duration of 50 fs to microfabricate gold IDEs having finger width from 2.3 μm up to 3.2 μm. The parameters used in the laser ablation technique, such as light intensity, scan speed and beam spot size have been optimized to achieve uniform IDEs, which were characterized by optical and scanning electron microscopy. The electrical properties of gold IDEs fabricated by laser ablation were evaluated by impedance spectroscopy, and compared to those produced by conventional photolithography. The results show that femtosecond laser ablation is a promising alternative to conventional photolithography for fabricating metal IDEs for e-tongue systems.

  20. Thermal analysis of intense femtosecond laser ablation of aluminum

    Institute of Scientific and Technical Information of China (English)

    Hu Hao-Feng; Ji Yang; Hu Yang; Ding Xiao-Yan; Liu Xian-Wen; Guo Jing-Hui; Wang Xiao-Lei; Zhai Hong-Chen

    2011-01-01

    This paper numerically simulates the process of ablation of an aluminum target by an intense femtosecond laser with a fluence of 40 J/cm2 based on the two-temperature equation, and obtains the evolution of the free electron temperature and lattice temperature over a large temporal and depth range, for the first time. By investigating the temporal evolution curves of the free electron temperature and lattice temperature at three representative depths of O,100 nm and 500 nm, it reveals different characteristics and mechanisms of the free electron temperature evolution at different depths. The results show that, in the intense femtosecond laser ablation of aluminum, the material ablation is mainly induced by the thermal conduction of free electrons, instead of the direct absorption of the laser energy;in addition, the thermal conduction of free electrons and the coupling effect between electrons and lattice will induce the temperature of free electrons deep inside the target to experience a process from increase to decrease and finally to increase again.

  1. Femtosecond x rays from laser-plasma accelerators

    International Nuclear Information System (INIS)

    Relativistic interaction of short-pulse lasers with underdense plasmas has recently led to the emergence of a novel generation of femtosecond x-ray sources. Based on radiation from electrons accelerated in plasma, these sources have the common properties to be compact and to deliver collimated, incoherent, and femtosecond radiation. In this article, within a unified formalism, the betatron radiation of trapped and accelerated electrons in the so-called bubble regime, the synchrotron radiation of laser-accelerated electrons in usual meter-scale undulators, the nonlinear Thomson scattering from relativistic electrons oscillating in an intense laser field, and the Thomson backscattered radiation of a laser beam by laser-accelerated electrons are reviewed. The underlying physics is presented using ideal models, the relevant parameters are defined, and analytical expressions providing the features of the sources are given. Numerical simulations and a summary of recent experimental results on the different mechanisms are also presented. Each section ends with the foreseen development of each scheme. Finally, one of the most promising applications of laser-plasma accelerators is discussed: the realization of a compact free-electron laser in the x-ray range of the spectrum. In the conclusion, the relevant parameters characterizing each sources are summarized. Considering typical laser-plasma interaction parameters obtained with currently available lasers, examples of the source features are given. The sources are then compared to each other in order to define their field of applications. (authors)

  2. Serial femtosecond crystallography: A revolution in structural biology.

    Science.gov (United States)

    Martin-Garcia, Jose M; Conrad, Chelsie E; Coe, Jesse; Roy-Chowdhury, Shatabdi; Fromme, Petra

    2016-07-15

    Macromolecular crystallography at synchrotron sources has proven to be the most influential method within structural biology, producing thousands of structures since its inception. While its utility has been instrumental in progressing our knowledge of structures of molecules, it suffers from limitations such as the need for large, well-diffracting crystals, and radiation damage that can hamper native structural determination. The recent advent of X-ray free electron lasers (XFELs) and their implementation in the emerging field of serial femtosecond crystallography (SFX) has given rise to a remarkable expansion upon existing crystallographic constraints, allowing structural biologists access to previously restricted scientific territory. SFX relies on exceptionally brilliant, micro-focused X-ray pulses, which are femtoseconds in duration, to probe nano/micrometer sized crystals in a serial fashion. This results in data sets comprised of individual snapshots, each capturing Bragg diffraction of single crystals in random orientations prior to their subsequent destruction. Thus structural elucidation while avoiding radiation damage, even at room temperature, can now be achieved. This emerging field has cultivated new methods for nanocrystallogenesis, sample delivery, and data processing. Opportunities and challenges within SFX are reviewed herein. PMID:27143509

  3. Optical cell cleaning with NIR femtosecond laser pulses

    Science.gov (United States)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-03-01

    Femtosecond laser microscopes have been used as both micro and nanosurgery tools. The optical knock-out of undesired cells in multiplex cell clusters shall be further reported on in this study. Femtosecond laser-induced cell death is beneficial due to the reduced collateral side effects and therefore can be used to selectively destroy target cells within monolayers, as well as within 3D tissues, all the while preserving cells of interest. This is an important characteristic for the application in stem cell research and cancer treatment. Non-precise damage compromises the viability of neighboring cells by inducing side effects such as stress to the cells surrounding the target due to the changes in the microenvironment, resulting from both the laser and laser-exposed cells. In this study, optimum laser parameters for optical cleaning by isolating single cells and cell colonies are exploited through the use of automated software control. Physiological equilibrium and cellular responses to the laser induced damages are also investigated. Cell death dependence on laser focus, determination and selectivity of intensity/dosage, controllable damage and cell recovery mechanisms are discussed.

  4. Femtosecond and nanometre visualization of structural dynamics in superheated nanoparticles

    Science.gov (United States)

    Gorkhover, Tais; Schorb, Sebastian; Coffee, Ryan; Adolph, Marcus; Foucar, Lutz; Rupp, Daniela; Aquila, Andrew; Bozek, John D.; Epp, Sascha W.; Erk, Benjamin; Gumprecht, Lars; Holmegaard, Lotte; Hartmann, Andreas; Hartmann, Robert; Hauser, Günter; Holl, Peter; Hömke, Andre; Johnsson, Per; Kimmel, Nils; Kühnel, Kai-Uwe; Messerschmidt, Marc; Reich, Christian; Rouzée, Arnaud; Rudek, Benedikt; Schmidt, Carlo; Schulz, Joachim; Soltau, Heike; Stern, Stephan; Weidenspointner, Georg; White, Bill; Küpper, Jochen; Strüder, Lothar; Schlichting, Ilme; Ullrich, Joachim; Rolles, Daniel; Rudenko, Artem; Möller, Thomas; Bostedt, Christoph

    2016-02-01

    The ability to observe ultrafast structural changes in nanoscopic samples is essential for understanding non-equilibrium phenomena such as chemical reactions, matter under extreme conditions, ultrafast phase transitions and intense light-matter interactions. Established imaging techniques are limited either in time or spatial resolution and typically require samples to be deposited on a substrate, which interferes with the dynamics. Here, we show that coherent X-ray diffraction images from isolated single samples can be used to visualize femtosecond electron density dynamics. We recorded X-ray snapshot images from a nanoplasma expansion, a prototypical non-equilibrium phenomenon. Single Xe clusters are superheated using an intense optical laser pulse and the structural evolution of the sample is imaged with a single X-ray pulse. We resolved ultrafast surface softening on the nanometre scale at the plasma/vacuum interface within 100 fs of the heating pulse. Our study is the first time-resolved visualization of irreversible femtosecond processes in free, individual nanometre-sized samples.

  5. Whole-pattern fitting technique in serial femtosecond nanocrystallography

    Science.gov (United States)

    Dilanian, Ruben A.; Williams, Sophie R.; Martin, Andrew V.; Streltsov, Victor A.; Quiney, Harry M.

    2016-01-01

    Serial femtosecond X-ray crystallography (SFX) has created new opportunities in the field of structural analysis of protein nanocrystals. The intensity and timescale characteristics of the X-ray free-electron laser sources used in SFX experiments necessitate the analysis of a large collection of individual crystals of variable shape and quality to ultimately solve a single, average crystal structure. Ensembles of crystals are commonly encountered in powder diffraction, but serial crystallography is different because each crystal is measured individually and can be oriented via indexing and merged into a three-dimensional data set, as is done for conventional crystallography data. In this way, serial femtosecond crystallography data lie in between conventional crystallography data and powder diffraction data, sharing features of both. The extremely small sizes of nanocrystals, as well as the possible imperfections of their crystallite structure, significantly affect the diffraction pattern and raise the question of how best to extract accurate structure-factor moduli from serial crystallography data. Here it is demonstrated that whole-pattern fitting techniques established for one-dimensional powder diffraction analysis can be feasibly extended to higher dimensions for the analysis of merged SFX diffraction data. It is shown that for very small crystals, whole-pattern fitting methods are more accurate than Monte Carlo integration methods that are currently used. PMID:27006776

  6. Whole-pattern fitting technique in serial femtosecond nanocrystallography

    Directory of Open Access Journals (Sweden)

    Ruben A. Dilanian

    2016-03-01

    Full Text Available Serial femtosecond X-ray crystallography (SFX has created new opportunities in the field of structural analysis of protein nanocrystals. The intensity and timescale characteristics of the X-ray free-electron laser sources used in SFX experiments necessitate the analysis of a large collection of individual crystals of variable shape and quality to ultimately solve a single, average crystal structure. Ensembles of crystals are commonly encountered in powder diffraction, but serial crystallography is different because each crystal is measured individually and can be oriented via indexing and merged into a three-dimensional data set, as is done for conventional crystallography data. In this way, serial femtosecond crystallography data lie in between conventional crystallography data and powder diffraction data, sharing features of both. The extremely small sizes of nanocrystals, as well as the possible imperfections of their crystallite structure, significantly affect the diffraction pattern and raise the question of how best to extract accurate structure-factor moduli from serial crystallography data. Here it is demonstrated that whole-pattern fitting techniques established for one-dimensional powder diffraction analysis can be feasibly extended to higher dimensions for the analysis of merged SFX diffraction data. It is shown that for very small crystals, whole-pattern fitting methods are more accurate than Monte Carlo integration methods that are currently used.

  7. A novel inert crystal delivery medium for serial femtosecond crystallography

    Directory of Open Access Journals (Sweden)

    Chelsie E. Conrad

    2015-07-01

    Full Text Available Serial femtosecond crystallography (SFX has opened a new era in crystallography by permitting nearly damage-free, room-temperature structure determination of challenging proteins such as membrane proteins. In SFX, femtosecond X-ray free-electron laser pulses produce diffraction snapshots from nanocrystals and microcrystals delivered in a liquid jet, which leads to high protein consumption. A slow-moving stream of agarose has been developed as a new crystal delivery medium for SFX. It has low background scattering, is compatible with both soluble and membrane proteins, and can deliver the protein crystals at a wide range of temperatures down to 4°C. Using this crystal-laden agarose stream, the structure of a multi-subunit complex, phycocyanin, was solved to 2.5 Å resolution using 300 µg of microcrystals embedded into the agarose medium post-crystallization. The agarose delivery method reduces protein consumption by at least 100-fold and has the potential to be used for a diverse population of proteins, including membrane protein complexes.

  8. Investigation of diffractive optical element femtosecond laser machining

    Science.gov (United States)

    Chabrol, Grégoire R.; Ciceron, Adline; Twardowski, Patrice; Pfeiffer, Pierre; Flury, Manuel; Mermet, Frédéric; Lecler, Sylvain

    2016-06-01

    This paper presents an explorative study on the machining of diffractive optical elements (DOEs) in transparent materials using a femtosecond laser source. A simple form of DOE, a binary phase grating with a period of 20.85 μm (σ = 0.5 μm), a groove depth and width of 0.7 μm (σ = 0.2 μm) and 8.8 μm (σ = 0.5 μm) respectively, was successfully machined in BK7. The topographic characteristics were measured by white light interferometry and scanning electron microscopy (SEM). The processing was carried out on high precision stages with an ultrafast fibre laser (350 fs) emitting a 343 nm pulse focused onto the sample with a stationary microscope objective. A diffracted efficiency of 27%, obtained with a spectro goniometer, was corroborated by the theoretical results obtained by the Fourier modal method (FMM), taking into account the measured topographic values. These encouraging results demonstrate that high-speed femtosecond laser manufacturing of DOE in bulk glasses can be achieved, opening the way to rapid prototyping of multi-layered-DOEs.

  9. Femtosecond Laser Cleaning of Metallic Cultural Heritage and Antique Artworks

    Science.gov (United States)

    Burmester, T.; Meier, M.; Haferkamp, H.; Barcikowski, S.; Bunte, J.; Ostendorf, A.

    Numereous metallic artworks show environmental damages. Often corrosion products and other contaminations can not be removed sufficiently by conventional techniques such as chemical cleaning agents. Within the framework of an 18-month project, LZH is carrying out investigations with the aim to develop a new cleaning method for antique metallic artworks with a temperature-sensitive surface using femtosecond (fs) laser technology to avoid damage or discoloring of the original surface. In the presented work the removal of corrosion products or pigment coatings from original objects made of copper, bronze and silver using a Titan-Saphir femtosecond laser is being investigated. This laser cleaning technology will be qualified at the end of the project by an exemplary restoration of a part of a bronze sculpture createtd by Adrian de Vries in 1648. In the frame of the project, the influence of the laser fluence and of the repetition rate on the specific removal efficiency of the various corrosion products is analysed. Specific fluence thresholds have been found for the removal of different types of corrosion products and pigment coatings. A sequential removal by non-thermal ablation of discrete corrosion layers or products has been achieved by varying the laser fluence.

  10. Two-photon coherent control of femtosecond photoassociation

    CERN Document Server

    Koch, Christiane P; Kosloff, Ronnie

    2008-01-01

    Photoassociation with short laser pulses has been proposed as a technique to create ultracold ground state molecules. A broad-band excitation seems the natural choice to drive the series of excitation and deexcitation steps required to form a molecule in its vibronic ground state from two scattering atoms. First attempts at femtosecond photoassociation were, however, hampered by the requirement to eliminate the atomic excitation leading to trap depletion. On the other hand, molecular levels very close to the atomic transition are to be excited. The broad bandwidth of a femtosecond laser then appears to be rather an obstacle. To overcome the ostensible conflict of driving a narrow transition by a broad-band laser, we suggest a two-photon photoassociation scheme. In the weak-field regime, a spectral phase pattern can be employed to eliminate the atomic line. When the excitation is carried out by more than one photon, different pathways in the field can be interfered constructively or destructively. In the stron...

  11. Microfabrication of transparent materials using filamented femtosecond laser beams

    Science.gov (United States)

    Butkus, S.; Paipulas, D.; Gaižauskas, Eugenijus; KaškelytÄ--, D.; Sirutkaitis, V.

    2014-05-01

    Glass drilling realized with the help of femtosecond lasers attract industrial attention, however, desired tasks may require systems employing high numerical aperture (NA) focusing conditions, low repetition rate lasers and complex fast motion translation stages. Due to the sensitivity of such systems, slight instabilities in parameter values can lead to crack formations, severe fabrication rate decrement and poor quality overall results. A microfabrication system lacking the stated disadvantages was constructed and demonstrated in this report. An f-theta lens was used in combination with a galvanometric scanner, in addition, a water pumping system that enables formation of water films of variable thickness in real time on the samples. Water acts as a medium for filament formation, which in turn decreases the focal spot diameter and increases fluence and axial focal length. This article demonstrates the application of a femtosecond (280fs) laser towards rapid cutting of different transparent materials. Filament formation in water gives rise to strong ablation at the surface of the sample, moreover, the water, surrounding the ablated area, adds increased cooling and protection from cracking. The constructed microfabrication system is capable of drilling holes in thick soda-lime, hardened glasses and sapphire. The fabrication time varies depending on the diameter of the hole and spans from a few to several hundred seconds. Moreover, complex-shape fabrication was demonstrated.

  12. Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuzhu, E-mail: yuzhu.liu@gmail.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Knopp, Gregor [Paul Scherrer Institute, Villigen 5232 (Switzerland); Qin, Chaochao [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Gerber, Thomas [Paul Scherrer Institute, Villigen 5232 (Switzerland)

    2015-01-13

    Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S{sub 2} to S{sub 1} is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S{sub 2} state to the vibrationally hot S{sub 1} state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S{sub 1} state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding.

  13. Bi-Plasma Interactions on Femtosecond Time-Scales

    Energy Technology Data Exchange (ETDEWEB)

    2011-06-22

    Ultrafast THz radiation has important applications in materials science studies, such as characterizing transport properties, studying the vibrational response of materials, and in recent years, controlling materials and elucidating their response in intense electromagnetic fields. THz fields can be generated in a lab setting using various plasma-based techniques. This study seeks to examine the interaction of two plasmas in order to better understand the fundamental physics associated with femtosecond filamentation processes and to achieve more efficient THz generation in a lab setting. The intensity of fluorescence in the region of overlap was measured as a function of polarization, power, and relative time delay of the two plasma-generating laser beams. Results of time dependent intensity studies indicate strikingly similar behaviors across polarizations and power levels; a sudden intensity spike was observed at time-zero, followed by a secondary maxima and subsequent decay to the initial plasma intensity. Dependence of the intensity on the power through either beam arm was also observed. Spectral studies of the enhanced emission were also carried out. Although this physical phenomenon is still not fully understood, future studies, including further spectral analysis of the fluorescence overlap, could yield new insight into the ultrafast processes occurring at the intersection of femtosecond filaments, and would provide a better understanding of the mechanisms for enhanced THz production.

  14. Synchronized videography of plasma plume expansion during femtosecond laser ablation

    Science.gov (United States)

    Paolasini, Steven; Kietzig, Anne

    2014-03-01

    Femtosecond lasers are gaining industrial interest for surface patterning and structuring because of the reduced heat effects to the surrounding material, resulting in a good quality product with a high aspect ratio. Analysis of the plasma plume generated during ablation can provide useful information about the laser-material interactions and thereby the quality of the resulting surface patterns. As a low-cost alternative to rather complicated ICCD camera setups, presented here is an approach based on filming the laser machining process with a high speed camera and tuning the frame rate of the camera to slightly lower than the laser pulse frequency. The delay in frequency between the laser and camera results in frames taken from sequential pulses. Each frame represents a later phase of plume expansion although taken from different pulses. Assuming equal plume evolution processes from pulse to pulse, the sequence of images obtained completes a plume expansion video. To test the assumption of homogeneity between sequential plumes, the camera can be tuned to the frequency of the laser, as to capture consecutive plumes at the same phase in their evolution. This approach enables a relatively low-cost, high resolution visualization of plasma plume evolution suitable for industrial micromachining applications with femtosecond lasers. Using this approach we illustrate differences in plume expansion at the example of machining homogeneous surface patterns in different liquid and gaseous processing environments.

  15. Calibration of femtosecond optical tweezers as a sensitive thermometer

    Science.gov (United States)

    Mondal, Dipankar; Goswami, Debabrata

    2015-08-01

    We present cumulative perturbation effects of femtosecond laser pulses on an optical tweezer. Our experiments involve a dual wavelength high repetition rate femtosecond laser, one at the non-heating wavelength of 780 nm while the other at 1560 nm to cause heating in the trapped volume under low power (100-800 μW) conditions. The 1560 nm high repetition rate laser acts as a resonant excitation source for the vibrational combination band of the hydroxyl group (OH) of water, which helps create the local heating effortlessly within the trapping volume. With such an experimental system, we are the first to observe direct effect of temperature on the corner frequency deduced from power spectrum. We can, thus, control and measure temperature precisely at the optical trap. This observation has lead us to calculate viscosity as well as temperature in the vicinity of the trapping zone. These experimental results also support the well-known fact that the nature of Brownian motion is the response of the optically trapped bead from the temperature change of surroundings. Temperature rise near the trapping zone can significantly change the viscosity of the medium. However, we notice that though the temperature and viscosity are changing as per our corner frequency calculations, the trap stiffness remains the same throughout our experiments within the temperature range of about 20 K.

  16. Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S2 to S1 is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S2 state to the vibrationally hot S1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding

  17. Direct patterning on reduced graphene oxide nanosheets using femtosecond laser pulses

    International Nuclear Information System (INIS)

    Micro- and nanostructures were fabricated directly on graphene nanosheets by controlling the conditions of femtosecond laser pulse etching. High quality graphene micro- and nanostructures with a minimum width of 492 nm were obtained as the graphene nanosheets used in our experiments were large-scale, uniform and highly conductive. Various complex patterns were successfully created through femtosecond laser etching. Furthermore, by managing the laser energy, the graphene under the Au electrodes could be completely or partly removed. This technology of direct patterning of micro- and nanostructures on graphene through femtosecond laser technology might pave the way for the integration of graphene-based electronic microdevices

  18. Influence of Femtosecond Laser Irradiation and Heat Treatment on Precipitation of Silver Nanoparticles in Glass

    Institute of Scientific and Technical Information of China (English)

    曾惠丹; 邱建荣; 姜雄伟; 曲士良; 朱从善; 干福熹

    2003-01-01

    Silver nanoparticles were precipitated inside an Ag2 O-doped glass by femtosecond laser irradiation and successive heat treatment. The influence of heat treatment temperature on the precipitation of silver nanoparticles was investigated. Absorption spectra show that the femtosecond laser irradiation results in an apparent decrease of the treatment temperature for the precipitation of Ag nanoparticles. We demonstrate the control of precipitation,dissolution and growth of silver nanoparticles inside glass by changing the heat treatment temperature or using further femtosecond laser irradiation.

  19. A higher-order-mode fiber delivery for Ti:Sapphire femtosecond lasers

    DEFF Research Database (Denmark)

    Jespersen, Kim Giessmann; Le, Tuan; Grüner-Nielsen, Lars Erik;

    2010-01-01

    We report the first higher-order-mode fiber with anomalous dispersion at 800nm and demonstrate its potential in femtosecond pulse delivery for Ti:Sapphire femtosecond lasers. We obtain 125fs pulses after propagating a distance of 3.6 meters in solid-silica fiber. The pulses could be further...... compressed in a quartz rod to nearly chirp-free 110fs pulses. Femtosecond pulse delivery is achieved by launching the laser output directly into the delivery fiber without any pre-chirping of the input pulse. The demonstrated pulse delivery scheme suggests scaling to >20meters for pulse delivery in harsh...

  20. A higher-order-mode fiber delivery for Ti:Sapphire femtosecond lasers

    OpenAIRE

    Jespersen, Kim Giessmann; Le, Tuan; Grüner-Nielsen, Lars Erik; Jakobsen, Dan; Pedersen, Martin Erland Vestergaard; Smedemand, Mikkel B.; Keiding, Søren; Palsdottir, Bera

    2010-01-01

    We report the first higher-order-mode fiber with anomalous dispersion at 800nm and demonstrate its potential in femtosecond pulse delivery for Ti:Sapphire femtosecond lasers. We obtain 125fs pulses after propagating a distance of 3.6 meters in solid-silica fiber. The pulses could be further compressed in a quartz rod to nearly chirp-free 110fs pulses. Femtosecond pulse delivery is achieved by launching the laser output directly into the delivery fiber without any pre-chirping of the input pul...

  1. Measurement of ablation threshold of oxide-film-coated aluminium nanoparticles irradiated by femtosecond laser pulses

    Science.gov (United States)

    Chefonov, O. V.; Ovchinnikov, A. V.; Il'ina, I. V.; Agranat, M. B.

    2016-03-01

    We report the results of experiments on estimation of femtosecond laser threshold intensity at which nanoparticles are removed from the substrate surface. The studies are performed with nanoparticles obtained by femtosecond laser ablation of pure aluminium in distilled water. The attenuation (or extinction, i.e. absorption and scattering) spectra of nanoparticles are measured at room temperature in the UV and optical wavelength ranges. The size of nanoparticles is determined using atomic force microscopy. A new method of scanning photoluminescence is proposed to evaluate the threshold of nanoparticle removal from the surface of a glass substrate exposed to IR femtosecond laser pulses with intensities 1011 – 1013 W cm-2.

  2. Hybrid femtosecond laser 3D microprocessing and application to biochip fabrication

    International Nuclear Information System (INIS)

    To fabricate highly functional biochips, we propose a novel technique termed hybrid femtosecond laser processing, in which femtosecond laser 3D glass micromachining (subtractive manufacturing) and two-photon polymerization (TPP) (additive manufacturing) are combined. In this process, 3D microfluidic structures are first formed inside the glass by femtosecond laser 3D glass micromachining, and functional micro and nano components are then integrated in the 3D microfluidics by TPP. We refer such glass microfluidics integrated with 3D polymer micro and nanostructures to as a ship-in-a-bottle biochip. (author)

  3. Femtosecond laser fabrication for the integration of optical sensors in microfluidic lab-on-chip devices

    OpenAIRE

    Osellame, R.; Martinez Vazquez, R.; Dongre, C.; Dekker, R.; Hoekstra, H.J.W.M.; Pollnau, M.; Ramponi, R.; Cerullo, G

    2008-01-01

    Femtosecond lasers enable the fabrication of both optical waveguides and buried microfluidic channels on a glass substrate. The waveguides are used to integrate optical detection in a commercial microfluidic lab-on-chip for capillary electrophoresis

  4. Spatiotemporal control of degenerate multiphoton fluorescence microscopy with delay-tunable femtosecond pulse pairs

    Science.gov (United States)

    Das, Dhiman; Bhattacharyya, Indrajit; Goswami, Debabrata

    2016-07-01

    Selective excitation of a particular fluorophore in an ensemble of different fluorophores with overlapping fluorescence spectra is shown to be dependent on the time delay of femtosecond pulse pairs in multiphoton fluorescence microscopy. In particular, the two-photon fluorescence behavior of the Texas Red and DAPI dye pair inside Bovine Pulmonary Artery Endothelial (BPAE) cells depends strongly on the center wavelength of the laser, as well as the delay between two identical laser pulses in one-color femtosecond pulse-pair excitation scheme. Thus, we present a novel design concept using pairs of femtosecond pulses at different central wavelengths and tunable pulse separations for controlling the image contrast between two spatially and spectrally overlapping fluorophores. This femtosecond pulse-pair technique is unique in utilizing the variation of dye dynamics inside biological cells as a contrast mode in microscopy of different fluorophores.

  5. Time-resolved spectroscopy of alkali clusters in the pico- and femtosecond time domain

    International Nuclear Information System (INIS)

    The wave packet propagation and fragmentation dynamics of small potassium and sodium clusters in a supersonic cluster beam had been investigated using pico- and femtosecond two-photon-ionization spectroscopy followed by mass-selective detection. (author)

  6. Direct measurement of the electron density of extended femtosecond laser pulse-induced filaments

    OpenAIRE

    Chen, Y.-H.; S. Varma; Antonsen, T. M.; Milchberg, H. M.

    2010-01-01

    We present direct time- and space- resolved measurements of the electron density of femtosecond laser pulse-induced plasma filaments. The dominant nonlinearity responsible for extended atmospheric filaments is shown to be field-induced rotation of air molecules.

  7. Application of femtosecond ultrashort pulse laser to photodynamic therapy mediated by indocyanine green

    OpenAIRE

    Sawa, M; Awazu, K; Takahashi, T.; Sakaguchi, H; Horiike, H.; Ohji, M; Tano, Y

    2004-01-01

    Backgrounds/aims: To evaluate treatment with high peak power pulse energy by femtosecond ultrashort pulse laser (titanium sapphire laser) delivered at an 800 nm wavelength for corneal neovascularisation using photodynamic therapy (PDT) mediated by indocyanine green (ICG).

  8. Integrated Optical sensing in a lab-on-chip by femtosecond laser written waveguides

    OpenAIRE

    Osellame, R.; Martinez Vazquez, R.; Ramponi, R.; Cerullo, G.; Dongre, C.; Dekker, R.; Hoekstra, H.J.W.M.; Pollnau, M

    2008-01-01

    Integrated optical detection in a commercial microfluidic chip for capillary electrophoresis has been implemented by means of femtosecond laser written optical waveguides for excitation and a high numerical aperture optical fiber for collection.

  9. Femtosecond dynamics of a spaser and unidirectional emission from a perfectly spherical nanoparticle

    KAUST Repository

    Gongora, Juan Sebastian Totero

    2015-01-01

    We investigate the femtosecond dynamics of the spaser emission by combining ab-initio simulations and thermodynamic analysis. Interestingly, the emission is characterized by rotational evolution, opening to the generation of unidirectional emission from perfectly spherical nanoparticles. © OSA 2015.

  10. Femtosecond oscillator on Yb:KYW crystal pumped by laser diode with fiber output

    Science.gov (United States)

    Kim, G. H.; Kang, U.; Heo, D.; Yashin, V. E.; Kulik, A. V.; Sall', E. G.; Chizhov, S. A.

    2010-05-01

    A femtosecond laser based on an Yb:KYW crystal with direct longitudinal pumping by a high-power semiconductor injection laser with a fiber output is described. Femtosecond pulses were generated in the self-longitudinal-mode-locking operating condition due to the use of a semiconductor saturable absorber. The average power of the oscillator was as high as 3.5 W at a central wavelength of 1035 nm, the pulse length and pulse repetition rate being 200 fs and 85.5 MHz, respectively. The product of the pulse length and the radiation spectrum width was 1.3 times higher than the theoretical limit for the pulse shape described by the function sech2. The designed master oscillator can be also used as a stand-alone source of femtosecond radiation pulses for material microprocessing and primary source for femtosecond laser amplification systems.

  11. Femtosecond Laser Desorption of Thin Polymer Films from a Dielectric Surface

    Directory of Open Access Journals (Sweden)

    Mercadier L.

    2013-11-01

    Full Text Available We desorb polymer films from fused silica with a femtosecond laser and characterize the results by atomic force microscopy. Our study as a function of beam geometry and energy reveals two ways of achieving spatially controlled nanodesorption.

  12. Giantically blue-shifted visible light in femtosecond mid-IR filament in fluorides

    CERN Document Server

    Dormidonov, A E; Chekalin, S V; Kandidov, V P

    2015-01-01

    A giant blue shift of an isolated visible band of supercontinuum was discovered and studied in the single filament regime of Mid-IR femtosecond laser pulse at powers slightly exceeding critical power for self-focusing in fluorides.

  13. In-situ femtosecond laser pulse characterization and compression during micromachining.

    Science.gov (United States)

    Zhu, Xin; Gunaratne, Tissa C; Lozovoy, Vadim V; Dantus, Marcos

    2007-11-26

    We report on phase measurements and adaptive phase distortion compensation of femtosecond pulses using multiphoton intrapulse interference phase scan (MIIPS) based on second harmonic generation in the plasma generated on the surface of silicon and metals. PMID:19550894

  14. An integrated fluorescence activated cell sorter fabricated by femtosecond laser micromachining

    Directory of Open Access Journals (Sweden)

    Paié P.

    2013-11-01

    Full Text Available We present here a fully integrated fluorescence activated cell sorter (FACS, able to perform analysis at single cell level. This optofluidic device is obtained on a fused silica substrate with the use of femtosecond laser micromachining.

  15. Evaluation of femtosecond laser-induced breakdown spectroscopy for explosive residue detection.

    Science.gov (United States)

    De Lucia, Frank C; Gottfried, Jennifer L; Miziolek, Andrzej W

    2009-01-19

    Recently laser-induced breakdown spectroscopy (LIBS) has been investigated as a potential technique for trace explosive detection. Typically LIBS is performed using nanosecond laser pulses. For this work, we have investigated the use of femtosecond laser pulses for explosive residue detection at two different fluences. Femtosecond laser pulses have previously been shown to provide several advantages for laser ablation and other LIBS applications. We have collected LIBS spectra of several bulk explosives and explosive residues at different pulse durations and energies. In contrast to previous femtosecond LIBS spectra of explosives, we have observed atomic emission peaks for the constituent elements of explosives - carbon, hydrogen, nitrogen, and oxygen. Preliminary results indicate that several advantages attributed to femtosecond pulses are not realized at higher laser fluences. PMID:19158854

  16. Ship-in-a-Bottle Biomicrochips Fabricated by Hybrid Femtosecond Laser Processing

    Directory of Open Access Journals (Sweden)

    Sugioka Koji

    2013-11-01

    Full Text Available We demonstrate fabrication of highly functional biomicrochips by hybrid femtosecond laser processing. In this process, 3D microfluidic structures are first formed inside photosensitive glass by femtosecond laser direct writing followed by thermal treatment and successive chemical wet etching. Then, functional microcomponents are integrated inside the fabricated microfluidic structures by two-photon photopolyerization. We term the fabricated microchips ship-in-a-bottle biomicrochips,

  17. A Comparison of Different Operating Systems for Femtosecond Lasers in Cataract Surgery

    OpenAIRE

    Wu, B. M.; Williams, G P; Tan, A; Mehta, J S

    2015-01-01

    The introduction of femtosecond lasers is potentially a major shift in the way we approach cataract surgery. The development of increasingly sophisticated intraocular lenses (IOLs), coupled with heightened patient expectation of high quality postsurgical visual outcomes, has generated the need for a more precise, highly reproducible and standardized method to carry out cataract operations. As femtosecond laser-assisted cataract surgery (FLACS) becomes more commonplace in surgical centers, fur...

  18. Introductory Lecture. Probing wavepacket dynamics with femtosecond energy- and angle-resolved photoelectron spectroscopy

    OpenAIRE

    Takatsuka, Kazuo; Arasaki, Yasuki; Wang, Kwanghsi; McKoy, Vincent

    2000-01-01

    Several recent studies have demonstrated how well-suited femtosecond time-resolved photoelectron spectra are for mapping wavepacket dynamics in molecular systems. Theoretical studies of femtosecond photoelectron spectra which incorporate a robust description of the underlying photoionization dynamics should enhance the utility of such spectra as a probe of wavepackets and of the evolution of electronic structure. This should be particularly true in regions of avoided crossings where the photo...

  19. Consequences of Femtosecond Laser Filament Generation Conditions in Standoff Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Brumfield, Brian E.; Phillips, Mark C.

    2016-08-08

    We investigate the role of femtosecond laser focusing conditions on ablation properties and its implications on analytical merits and standoff detection applications. Femtosecond laser pulses can be used for ablation either by tightly focusing or by using filaments generated during its propagation. We evaluated the persistence of atomic, and molecular emission features as well as time evolution of the fundamental properties (temperature and density) of ablation plumes generated using different methods.

  20. Optical beam dynamics in a gas repetitively heated by femtosecond filaments

    CERN Document Server

    Jhajj, N; Wahlstrand, J K; Milchberg, H M

    2013-01-01

    We investigate beam pointing dynamics in filamentation in gases driven by high repetition rate femtosecond laser pulses. Upon suddenly exposing a gas to a kilohertz train of filamenting pulses, the filament is steered from its original direction to a new stable direction whose equilibrium is determined by a balance among buoyant, viscous, and diffusive processes in the gas. Results are shown for Xe and air, but are broadly applicable to all configurations employing high repetition rate femtosecond laser propagation in gases.

  1. Femtosecond lenticule extraction for correction of myopia: a 6 month follow-up study

    OpenAIRE

    Demirok A; Agca A; Ozgurhan EB; Bozkurt E; Celik U; Demircan A; Guleryuz NB; Cankaya KI; Yilmaz OF

    2013-01-01

    Ahmet Demirok,1 Alper Agca,2 Engin Bilge Ozgurhan,2 Ercument Bozkurt,2 Ugur Celik,2 Ali Demircan,2 Nimet Burcu Guleryuz,2 Kadir Ilker Cankaya,2 Omer Faruk Yilmaz3 1Department of Ophthalmology, Medeniyet University, Istanbul, Turkey; 2Beyoglu Eye Training and Research Hospital, Istanbul, Turkey, 3Private Practice, Istanbul, Turkey Aims: To report our initial experience with femtosecond lenticule extraction (FLEX) compared with femtosecond laser-assisted in situ keratomileusis (LASIK). Settings...

  2. Femtosecond lenticule extraction for correction of myopia: a 6 month follow-up study

    OpenAIRE

    Celik, Ugur

    2013-01-01

    Ahmet Demirok,1 Alper Agca,2 Engin Bilge Ozgurhan,2 Ercument Bozkurt,2 Ugur Celik,2 Ali Demircan,2 Nimet Burcu Guleryuz,2 Kadir Ilker Cankaya,2 Omer Faruk Yilmaz3 1Department of Ophthalmology, Medeniyet University, Istanbul, Turkey; 2Beyoglu Eye Training and Research Hospital, Istanbul, Turkey, 3Private Practice, Istanbul, Turkey Aims: To report our initial experience with femtosecond lenticule extraction (FLEX) compared with femtosecond laser-assisted in situ keratomileusis (LASIK). Setting...

  3. Femtosecond time-resolved molecular multiphoton ionization: the Na_2 system

    OpenAIRE

    Baumert, Thomas,; Grosser, M.; Thalweiser, Rainer; Gerber, Gustav

    1991-01-01

    We report here the first experimental study of femtosecond time-resolved molecular multiphoton ionization. Femtosecond pump-probe techniques are combined with time-of-flight spectroscopy to measure transient ionization spectra of Na_2 in a molecular-beam experiment. The wave-packet motions in different molecular potentials show that incoherent contributions from direct photoionization of a singly excited state and from excitation and autoionization of a bound doubly excited molecu...

  4. Enhancement of femtosecond lenticule extraction for visual symptomatic eye after myopia correction

    OpenAIRE

    Zhao, Jing; Yao, Peijun; Chen, Zhi; Li, Meiyan; Shen, Yang; Miao, Huamao; Zhou, Xingtao

    2014-01-01

    Background The novel Femtosecond lenticule extraction (FLEx) procedure has been considered safe, predictable, and effective in treating myopia and myopic astigmatism, with few complications. However, an enhancement procedure after FLEx may be required in some cases, but has not been reported in detail. Case presentation A 24-year-old woman who had undergone bilateral FLEx with the VisuMax femtosecond laser treatment for myopic astigmatism complained of double vision in her left eye after the ...

  5. Direct synthesis of sp-bonded carbon chains on graphite surface by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Microscopic phase transformation from graphite to sp-bonded carbon chains (carbyne) and nanodiamond has been induced by femtosecond laser pulses on graphite surface. UV/surface enhanced Raman scattering spectra and x-ray photoelectron spectra displayed the local synthesis of carbyne in the melt zone while nanocrystalline diamond and trans-polyacetylene chains form in the edge area of gentle ablation. These results evidence possible direct 'writing' of variable chemical bonded carbons by femtosecond laser pulses for carbon-based applications

  6. Polycrystalline VO2 thin films via femtosecond laser processing of amorphous VO x

    Science.gov (United States)

    Charipar, N. A.; Kim, H.; Breckenfeld, E.; Charipar, K. M.; Mathews, S. A.; Piqué, A.

    2016-05-01

    Femtosecond laser processing of pulsed laser-deposited amorphous vanadium oxide thin films was investigated. Polycrystalline VO2 thin films were achieved by femtosecond laser processing in air at room temperature. The electrical transport properties, crystal structure, surface morphology, and optical properties were characterized. The laser-processed films exhibited a metal-insulator phase transition characteristic of VO2, thus presenting a pathway for the growth of crystalline vanadium dioxide films on low-temperature substrates.

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

    Science.gov (United States)

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

    2015-02-01

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

  8. Mechanism study of femtosecond laser induced selective metallization (FLISM) on glass surfaces

    Science.gov (United States)

    Xu, Jian; Liao, Yang; Zeng, Huidan; Cheng, Ya; Xu, Zhizhan; Sugioka, Koji; Midorikawa, Katsumi

    2008-07-01

    We investigate the mechanism of selective metallization on glass surfaces with the assistance of femtosecond laser irradiation followed by electroless plating. Irradiation of femtosecond laser makes it possible to selectively deposit copper microstructures in the irradiated area on glass surfaces coated with silver nitrate films. The energy-dispersive X-ray (EDX) analyses reveal that silver atoms are produced on the surface of grooves formed by laser ablation, which serve as catalysis seeds for subsequent electroless copper plating.

  9. Advances in Femtosecond Micromachining and Inscription of Micro and Nano Photonic Devices

    OpenAIRE

    Smith, Graham N; Kalli, Kyriacos; Sugden, Kate

    2010-01-01

    The use of focussed femtosecond laser pulses to fundamentally change materials through the interaction of the pulse and material offers new opportunities in device design. This is especially true for fabrication of intricate microstructures within the bulk volume of optically transparent glassy or polymeric materials. But it also can give significant advantages for the micromachining of surface structures in opaque materials in terms of feature size and aspect ratio. Although femtosecond lase...

  10. Femtosecond laser direct written diffractive optical elements and their integration in oxide glass

    Science.gov (United States)

    Choi, Jiyeon; Richardson, Martin

    2009-02-01

    Femtosecond laser direct writing was applied to fabricate 3D diffractive optical elements in oxide glass. Here we report our initial results. We describe the consequences of fabricating Fresnel Zone Plates (FZPs) with various femtosecond laser parameters. Single or multiple layers of laser written FZPs were produced in borosilicate glasses. We are investigating the diffraction efficiencies as a function of laser and writing parameters such as pulse energy, writing speed and repetition rate.

  11. Femtosecond laser direct writing of three-dimensional micro/nanofluidics in porous glass

    OpenAIRE

    Ya Cheng; Liao Yang; Sugioka Koji

    2013-01-01

    In this contribution, we show that 3D micro-/nanofluidic components with arbitrary geometries and configurations can be directly formed inside glass by femtosecond laser direct writing. We further demonstrate that nanofluidic channels of a width of ~40 nm can be directly fabricated in glass with linearly polarized femtosecond laser pulses, enabled by intentionally producing embedded nanograting structures with laser intensities slightly above a threshold value.

  12. Fabrication of surface nanoscale axial photonics (SNAP) structures with a femtosecond laser

    CERN Document Server

    Shen, Fangcheng; Zhang, Lin; Sumetsky, M

    2016-01-01

    Surface nanoscale axial photonics (SNAP) structures are fabricated with a femtosecond laser for the first time. The inscriptions introduced by the laser pressurize the fiber and cause its nanoscale effective radius variation. We demonstrate the subangstrom precise fabrication of individual and coupled SNAP microresonators having the effective radius variation of several nanometers. Our results pave the way to a novel ultraprecise SNAP fabrication technology based on the femtosecond laser inscription.

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

    OpenAIRE

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

    2014-01-01

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

  14. Synchronization of Distant Optical Clocks at the Femtosecond Level

    CERN Document Server

    Deschenes, Jean-Daniel; Giorgetta, Fabrizio R; Swann, William C; Baumann, Esther; Bergeron, Hugo; Cermak, Michael; Coddington, Ian; Newbury, Nathan R

    2015-01-01

    The use of optical clocks/oscillators in future ultra-precise navigation, gravitational sensing, and relativity experiments will require time comparison and synchronization over terrestrial or satellite free-space links. Here we demonstrate full unambiguous synchronization of two optical timescales across a free-space link. The time deviation between synchronized timescales is below 1 fs over durations from 0.1 s to 6500 s, despite atmospheric turbulence and kilometer-scale path length variations. Over several days, the time wander is below +/-20 fs. Our approach relies on the two-way reciprocity of a single-spatial-mode optical link, valid to below 225 attoseconds across a turbulent 4-km path. This femtosecond level of time-frequency transfer should enable optical networks using state-of-the-art optical clocks/oscillators.

  15. Optimized LWIR enhancement of nanosecond and femtosecond LIBS uranium emission

    Science.gov (United States)

    Akpovo, Codjo A.; Ford, Alan; Johnson, Lewis

    2016-05-01

    A carbon dioxide (CO2) transverse electrical breakdown in atmosphere (TEA), pulsed laser was used to enhance the laser-induced breakdown spectroscopy (LIBS) spectral signatures of uranium under nanosecond (ns) and femtosecond (fs) ablation. The peak areas of both ionic and neutral species increased by one order of magnitude for ns-ablation and two orders of magnitude for fs-ablation over LIBS when the CO2 TEA laser was used with samples of dried solutions of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) on silicon wafers. Electron temperature and density measurements show that the spectral emission improvement from using the TEA laser comes from plasma reheating.

  16. Generating long sequences of high-intensity femtosecond pulses

    CERN Document Server

    Bitter, Martin

    2015-01-01

    We present an approach to create pulse sequences extending beyond 150~picoseconds in duration, comprised of $100~\\mu$J femtosecond pulses. A quarter of the pulse train is produced by a high-resolution pulse shaper, which allows full controllability over the timing of each pulse. Two nested Michelson interferometers follow to quadruple the pulse number and the sequence duration. To boost the pulse energy, the long train is sent through a multi-pass Ti:Sapphire amplifier, followed by an external compressor. A periodic sequence of 84~pulses of 120~fs width and an average pulse energy of 107~$\\mu$J, separated by 2~ps, is demonstrated as a proof of principle.

  17. Femtosecond Pulse Propagation in a Highly Nonlinear Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    J. F. Gabayno

    2004-12-01

    Full Text Available Femtosecond pulses are launched into a highly nonlinear photonic crystal fiber (PCF. The input and output spectra were measured using a monochromator and streak camera. The spectrum of the output from a 50 cm PCF pumped at 794 nm for different pump powers features asymmetric side lobes due to intrapulse Raman scattering. Similar measurements on a 100 cm PCF pumped at 795 nm highlight the appearance of blueshifted peaks as a result of energy transfer of solitons to dispersive waves. Broadening in the spectrum is observed and attributed to Raman-scattering-induced soliton self-frequency shift. Spectrograms of both input and output pulses into a 50 cm PCF are captured using a streak camera. The spectrum reveals that individual modes observed on the spectrogram are actually a decomposition of the input pulse.

  18. Data processing pipeline for serial femtosecond crystallography at SACLA1

    Science.gov (United States)

    Nakane, Takanori; Joti, Yasumasa; Tono, Kensuke; Yabashi, Makina; Nango, Eriko; Iwata, So; Ishitani, Ryuichiro; Nureki, Osamu

    2016-01-01

    A data processing pipeline for serial femtosecond crystallography at SACLA was developed, based on Cheetah [Barty et al. (2014). J. Appl. Cryst.47, 1118–1131] and CrystFEL [White et al. (2016). J. Appl. Cryst.49, 680–689]. The original programs were adapted for data acquisition through the SACLA API, thread and inter-node parallelization, and efficient image handling. The pipeline consists of two stages: The first, online stage can analyse all images in real time, with a latency of less than a few seconds, to provide feedback on hit rate and detector saturation. The second, offline stage converts hit images into HDF5 files and runs CrystFEL for indexing and integration. The size of the filtered compressed output is comparable to that of a synchrotron data set. The pipeline enables real-time feedback and rapid structure solution during beamtime.

  19. Multiterawatt femtosecond laser system with kilohertz pulse repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, V V; Pestryakov, E V; Laptev, A V; Petrov, V A; Kuptsov, G V; Trunov, V I; Frolov, S A [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-05-30

    The basic principles, layout and components are presented for a multiterawatt femtosecond laser system with a kilohertz pulse repetition rate f, based on their parametric amplification and laser amplification of picosecond radiation that pumps the stages of the parametric amplifier. The results of calculations for a step-by-step increase in the output power from the LBO crystal parametric amplifier channel up to the multiterawatt level are presented. By using the developed components in the pump channel of the laser system, the parameters of the regenerative amplifier with the output energy ∼1 mJ at the wavelength 1030 nm and with f = 1 kHz are experimentally studied. The optical scheme of the diode-pumped multipass cryogenic Yb:Y{sub 2}O{sub 3} laser ceramic amplifier is developed and its characteristics are determined that provide the output energy within the range 0.25 – 0.35 J. (lasers)

  20. Multiterawatt femtosecond laser system with kilohertz pulse repetition rate

    Science.gov (United States)

    Petrov, V. V.; Pestryakov, E. V.; Laptev, A. V.; Petrov, V. A.; Kuptsov, G. V.; Trunov, V. I.; Frolov, S. A.

    2014-05-01

    The basic principles, layout and components are presented for a multiterawatt femtosecond laser system with a kilohertz pulse repetition rate f, based on their parametric amplification and laser amplification of picosecond radiation that pumps the stages of the parametric amplifier. The results of calculations for a step-by-step increase in the output power from the LBO crystal parametric amplifier channel up to the multiterawatt level are presented. By using the developed components in the pump channel of the laser system, the parameters of the regenerative amplifier with the output energy ~1 mJ at the wavelength 1030 nm and with f = 1 kHz are experimentally studied. The optical scheme of the diode-pumped multipass cryogenic Yb:Y2O3 laser ceramic amplifier is developed and its characteristics are determined that provide the output energy within the range 0.25 - 0.35 J.

  1. Reinforced direct bonding of optical materials by femtosecond laser welding.

    Science.gov (United States)

    Hélie, David; Bégin, Michael; Lacroix, Fabrice; Vallée, Réal

    2012-04-20

    A process for reinforcing a direct bond between optical materials using femtosecond laser welding is presented. As a side benefit, the optical transmission properties of the joined components are shown not to be altered by the joining process. The joints exhibits higher shear breakage loads, yielding a maximum measured joint strength of 5.25 MPa for an applied load of 75 kg in fused silica. The laser sealing of direct bonds between dissimilar materials improves their resistance to thermal shocks. Direct bonds sealed by a circular weld seam can withstand thermal shocks at temperatures at least twice as great as nonreinforced direct bonds. The combination of ultrashort laser welding and direct bonding provides an innovative joining method that benefits from the advantages of both contributing physical processes. PMID:22534922

  2. Oxygen assisted interconnection of silver nanoparticles with femtosecond laser radiation

    International Nuclear Information System (INIS)

    Ablation of silver (Ag) nanoparticles in the direction of laser polarization is achieved by utilizing femtosecond laser irradiation in air at laser fluence ranging from ∼2 mJ/cm2 to ∼14 mJ/cm2. This directional ablation is attributed to localized surface plasmon induced localized electric field enhancement. Scanning electron microscopy observations of the irradiated particles in different gases and at different pressures indicate that the ablation is further enhanced by oxygen in the air. This may be due to the external heating via the reactions of its dissociation product, atomic oxygen, with the surface of Ag particles, while the ablated Ag is not oxidized. Further experimental observations show that the ablated material re-deposits near the irradiated particles and results in the extension of the particles in laser polarization direction, facilitating the interconnection of two well-separated nanoparticles

  3. Ferroelectric domain engineering by focused infrared femtosecond pulses

    International Nuclear Information System (INIS)

    We demonstrate infrared femtosecond laser-induced inversion of ferroelectric domains. This process can be realised solely by using tightly focused laser pulses without application of any electric field prior to, in conjunction with, or subsequent to the laser irradiation. As most ferroelectric crystals like LiNbO3, LiTaO3, and KTiOPO4 are transparent in the infrared, this optical poling method allows one to form ferroelectric domain patterns much deeper inside a ferroelectric crystal than by using ultraviolet light and hence can be used to fabricate practical devices. We also propose in situ diagnostics of the ferroelectric domain inversion process by monitoring the Čerenkov second harmonic signal, which is sensitive to the appearance of ferroelectric domain walls

  4. Femtosecond infrared spectroscopy of channelrhodopsin-1 chromophore isomerization

    Science.gov (United States)

    Stensitzki, T.; Yang, Y.; Muders, V.; Schlesinger, R.; Heberle, J.; Heyne, K.

    2016-01-01

    Vibrational dynamics of the retinal all-trans to 13-cis photoisomerization in channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) was investigated by femtosecond visible pump mid-IR probe spectroscopy. After photoexcitation, the transient infrared absorption of C-C stretching modes was detected. The formation of the 13-cis photoproduct marker band at 1193 cm−1 was observed within the time resolution of 0.3 ps. We estimated the photoisomerization yield to (60 ± 6) %. We found additional time constants of (0.55 ± 0.05) ps and (6 ± 1) ps, assigned to cooling, and cooling processes with a back-reaction pathway. An additional bleaching band demonstrates the ground-state heterogeneity of retinal.

  5. Influence of coherent adiabatic excitation on femtosecond transient signals

    CERN Document Server

    Conde, A Peralta; Longarte, A

    2016-01-01

    The transient signals derived from femtosecond pump-probe experiments are analyzed in terms of the coherent evolution of the energy levels perturbed by the excitation pulse. The model system is treated as the sum of independent two-level subsystems that evolve adiabatically or are permanently excited, depending on the detuning from the central wavelength of the excitation laser. This approach will allow us to explain numerically and analytically the convergence between the coherent and incoherent (rate equations) treatments for complex multi-level systems. It will be also shown that the parameter that determines the validity of the incoherent treatment is the distribution of states outside and inside the laser bandwidth, rather than the density of states as it is commonly accepted.

  6. Transient light absorption induced in glassby femtosecond laser pulses

    International Nuclear Information System (INIS)

    The dynamics of the transient light absorption induced in K8 optical glass by filamented femtosecond laser pulses have been studied using time-resolved transmitted-light microscopy at wavelengths from 450 to 700 nm. The transient absorption measured as a function of probe beam wavelength is compared to that predicted by the Drude plasma model. We conclude that, just 450 fs after a pump pulse, the transient absorption is dominated by transient electronic states, presumably, self-trapped excitons, with an excitation energy of 2.6 - 2.7 eV. These states are filled with free-carriers from a long-lived plasma, which acts as a 'carrier reservoir'. The relaxation of transient absorption has two components. The slow component, with τ1 ∼ 17-17.5 ps, is governed by the plasma thermalisation time, whereas the second, with τ1 >> 300 ps, is determined by the plasma lifetime. (nonlinear optical phenomena)

  7. Computational modeling of femtosecond optical solitons from Maxwell's equations

    Science.gov (United States)

    Goorjian, Peter M.; Taflove, Allen; Joseph, Rose M.; Hagness, Susan C.

    1992-01-01

    An algorithm is developed that permits the direct time integration of full-vector nonlinear Maxwell's equations. This capability permits the modeling of both linear and nonlinear instantaneous and dispersive effects in the electric polarization in material media. The modeling of the optical carrier is retained. The fundamental innovation is to notice that it is possible to treat the linear and nonlinear convolution integrals, which describe the dispersion, as new dependent variables. A coupled system of nonlinear second-order ordinary differential equations can then be derived for the linear and nonlinear convolution integrals, by differentiating them in the time domain. These equations, together with Maxwell's equations, are solved to determine the electromagnetic fields in nonlinear dispersive media. Results are presented of calculations in one dimension of the propagation and collision of femtosecond electromagnetic solitons that retain the optical carrier, taking into account as the Kerr and Raman interactions.

  8. Polarization maintaining linear cavity Er-doped fiber femtosecond laser

    Science.gov (United States)

    Jang, Heesuk; Jang, Yoon-Soo; Kim, Seungman; Lee, Keunwoo; Han, Seongheum; Kim, Young-Jin; Kim, Seung-Woo

    2015-10-01

    We present a polarization-maintaining (PM) type of Er-doped fiber linear oscillator designed to produce femtosecond laser pulses with high operational stability. Mode locking is activated using a semiconductor saturable absorber mirror (SESAM) attached to one end of the linear PM oscillator. To avoid heat damage, the SESAM is mounted on a copper-silicon-layered heat sink and connected to the linear oscillator through a fiber buffer dissipating the residual pump power. A long-term stability test is performed to prove that the proposed oscillator design maintains a soliton-mode single-pulse operation without breakdown of mode locking over a week period. With addition of an Er-doped fiber amplifier, the output power is raised to 180 mW with 60 fs pulse duration, from which an octave-spanning supercontinuum is produced.

  9. Femtosecond Time-resolved MeV Electron Diffraction

    CERN Document Server

    Zhu, Pengfei; Cao, J; Geck, J; Hidaka, Y; Kraus, R; Pjerov, S; Shen, Y; Tobey, R I; Zhu, Y; Hill, J P; Wang, X J

    2013-01-01

    We report the experimental demonstration of electron diffraction with 130 femtosecond time resolution using bench-top MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminium and single-crystal 1T-TaS_{2} are obtained utilizing a 5 femto-Coulomb (~3x10^{4} electrons) pulse of electrons at 2.8 MeV. The timing jitter between the pump laser and probe electron beam was found to be ~ 100 fs. The time resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS_{2} following an optical pump. Our experiemntal results demonstrate the feasibility of ultimately realizing 40 fs time-resolved electron diffraction.

  10. Hot ion generation from nanostructured surfaces under intense, femtosecond irradiation

    CERN Document Server

    Bagchi, S; Bhuyan, M K; Bose, S; Kiran, P P; Krishnamurthy, M; Kumar, G R

    2006-01-01

    We present the effect of a nanostructured surface on the emission of ions and electrons from intense (5-36 Petwatt per sq.cm) femtosecond laser produced plasmas. Electrons from optically polished copper targets coated with copper nanoparticles (CuNP) are observed to be hotter than those from uncoated polished targets. A nearly two-fold enhancement is observed for ions in the range 14-74 keV, while ion yield decreases by a factor of 2 in the 74-2000 keV range. The total ion yields measured using a large area Faraday cup are more from CuNP targets than those from polished Cu targets, indicating increased ion beam divergence due to surface modulations.

  11. Femtosecond x-ray diffraction: experiments and limits

    Science.gov (United States)

    Wark, Justin S.; Allen, A. M.; Ansbro, P. C.; Bucksbaum, Philip H.; Chang, Zenghu; DeCamp, Mark F.; Falcone, Roger W.; Heimann, Philip A.; Johnson, S. L.; Kang, Inuk; Kapteyn, Henry C.; Larsson, Jorgen; Lee, Richard W.; Lindenberg, Aaron; Merlin, Roberto D.; Missalla, Thomas; Naylor, G.; Padmore, Howard A.; Reis, David A.; Scheidt, K.; Sjoegren, Anders; Sondhauss, P. C.; Wulff, Michael

    2001-01-01

    Although the realisation of femtosecond X-ray free electron laser (FEL) X-ray pulses is still some time away, X-ray diffraction experiments within the sub-picosecond domain are already being performed using both synchrotron and laser- plasma based X-ray sources. Within this paper we summarise the current status of some of these experiments which, to date, have mainly concentrated on observing non-thermal melt and coherent phonons in laser-irradiated semiconductors. Furthermore, with the advent of FEL sources, X-ray pulse lengths may soon be sufficiently short that the finite response time of monochromators may themselves place fundamental limits on achievable temporal resolution. A brief review of time-dependent X-ray diffraction relevant to such effects is presented.

  12. Oxygen assisted interconnection of silver nanoparticles with femtosecond laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Zhou, Y., E-mail: nzhou@uwaterloo.ca [Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Duley, W. W. [Centre for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-12-14

    Ablation of silver (Ag) nanoparticles in the direction of laser polarization is achieved by utilizing femtosecond laser irradiation in air at laser fluence ranging from ∼2 mJ/cm{sup 2} to ∼14 mJ/cm{sup 2}. This directional ablation is attributed to localized surface plasmon induced localized electric field enhancement. Scanning electron microscopy observations of the irradiated particles in different gases and at different pressures indicate that the ablation is further enhanced by oxygen in the air. This may be due to the external heating via the reactions of its dissociation product, atomic oxygen, with the surface of Ag particles, while the ablated Ag is not oxidized. Further experimental observations show that the ablated material re-deposits near the irradiated particles and results in the extension of the particles in laser polarization direction, facilitating the interconnection of two well-separated nanoparticles.

  13. Femtosecond infrared spectroscopy of channelrhodopsin-1 chromophore isomerization.

    Science.gov (United States)

    Stensitzki, T; Yang, Y; Muders, V; Schlesinger, R; Heberle, J; Heyne, K

    2016-07-01

    Vibrational dynamics of the retinal all-trans to 13-cis photoisomerization in channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) was investigated by femtosecond visible pump mid-IR probe spectroscopy. After photoexcitation, the transient infrared absorption of C-C stretching modes was detected. The formation of the 13-cis photoproduct marker band at 1193 cm(-1) was observed within the time resolution of 0.3 ps. We estimated the photoisomerization yield to (60 ± 6) %. We found additional time constants of (0.55 ± 0.05) ps and (6 ± 1) ps, assigned to cooling, and cooling processes with a back-reaction pathway. An additional bleaching band demonstrates the ground-state heterogeneity of retinal. PMID:27191011

  14. Removal of Retained Descemets Membrane Using Femtosecond Laser

    Science.gov (United States)

    May, William; Alrashidi, Sultan; Daoud, Yassine J.

    2016-01-01

    We present a unique method of retrocorneal membrane removal with a femtosecond laser (FSL). A 22-year-old male who had undergone penetrating keratoplasty had a retained retrocorneal membrane and a double anterior chamber postoperatively. The membrane was dissected completely with the FSL and the free-floating membrane was removed. Histopathological evaluation confirmed the diagnosis of retained Descemets membrane (DM). There was improvement in uncorrected visual acuity from 20/300 to 20/50. Central corneal endothelial cell count was 810 cells/mm2 preoperatively and 778 cells/mm2 postoperatively. Inadvertent retention of DM may be safely treated with the FSL. Clarity and viability of the existing graft can be maintained. PMID:27555712

  15. Femtosecond Laser Patterning of the Biopolymer Chitosan for Biofilm Formation

    Science.gov (United States)

    Estevam-Alves, Regina; Ferreira, Paulo Henrique Dias; Coatrini, Andrey C.; Oliveira, Osvaldo N.; Fontana, Carla Raquel; Mendonca, Cleber Renato

    2016-01-01

    Controlling microbial growth is crucial for many biomedical, pharmaceutical and food industry applications. In this paper, we used a femtosecond laser to microstructure the surface of chitosan, a biocompatible polymer that has been explored for applications ranging from antimicrobial action to drug delivery. The influence of energy density on the features produced on chitosan was investigated by optical and atomic force microscopies. An increase in the hydrophilic character of the chitosan surface was attained upon laser micromachining. Patterned chitosan films were used to observe Staphylococcus aureus (ATCC 25923) biofilm formation, revealing an increase in the biofilm formation in the structured regions. Our results indicate that fs-laser micromachining is an attractive option to pattern biocompatible surfaces, and to investigate basic aspects of the relationship between surface topography and bacterial adhesion. PMID:27548153

  16. Theoretical Femtosecond Physics Atoms and Molecules in Strong Laser Fields

    CERN Document Server

    Grossmann, Frank

    2008-01-01

    Theoretical femtosecond physics is a new field of research. Theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers of up to atomic field strengths are leading to an understanding of many challenging experimental discoveries. Laser-matter interaction is treated on a nonperturbative level in the book using approximate and numerical solutions of the time-dependent Schrödinger equation. The light field is treated classically. Physical phenomena, ranging from ionization of atoms to the ionization and dissociation of molecules and the control of chemical reactions are presented and discussed. Theoretical background for experiments with strong and short laser pulses is given. Several exercises are included in the main text. Some detailed calculations are performed in the appendices.

  17. Femtosecond ultraviolet (248 nm) excimer laser processing of Teflon (PTFE)

    International Nuclear Information System (INIS)

    We have investigated by X-ray photoelectron spectroscopy (XPS) the surface of poly(tetrafluoroethylene) (PTFE) films, which were subjected to processing by femtosecond (fs) UV radiation from an excimer laser (KrF: λ=248 nm, tp∼380 fs) in air. Bulk characterization of processed PTFE films by Fourier transform infrared spectroscopy (FTIR) permit an investigation of the laser induced modifications in the material at energy densities below the ablation threshold. No features in XPS and FTIR spectra indicated the incorporation of hydrogen and/or oxygen, or the formation of a cross-linked network of carbon indicating chemically clean processing in contrast to nanosecond excimer laser processing which chemically degrades the surface. Scanning electron microscopy (SEM) of the micrometer size vertical interconnect (microvia) indicated mechanically and thermally damage free processing of PTFE with good edge quality, in contrast to nanosecond excimer laser processing

  18. Microcrystal delivery by pulsed liquid droplet for serial femtosecond crystallography.

    Science.gov (United States)

    Mafuné, Fumitaka; Miyajima, Ken; Tono, Kensuke; Takeda, Yoshihiro; Kohno, Jun Ya; Miyauchi, Naoya; Kobayashi, Jun; Joti, Yasumasa; Nango, Eriko; Iwata, So; Yabashi, Makina

    2016-04-01

    A liquid-droplet injector has been developed that delivers pristine microcrystals to an X-ray irradiation area for conducting serial femtosecond crystallography (SFX) with an X-ray free-electron laser (XFEL). By finely tuning the pulsed liquid droplets in time and space, a high hit rate of the XFEL pulses to microcrystals in the droplets was achieved for measurements using 5 µm tetragonal lysozyme crystals, which produced 4265 indexable diffraction images in about 30 min. The structure was determined at a resolution of 2.3 Å from <0.3 mg of protein. With further improvements such as reduction of the droplet size, liquid droplets have considerable potential as a crystal carrier for SFX with low sample consumption. PMID:27050131

  19. Adiabatic Floquet model for the optical response in femtosecond filaments

    CERN Document Server

    Hofmann, Michael

    2016-01-01

    The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as free according to the Drude model, while the nonlinear response of the bound carriers follows the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes of filament simulation.

  20. Influence of ambient medium on femtosecond laser processing of silicon

    International Nuclear Information System (INIS)

    Femtosecond laser radiation (800 nm, 250 fs, 1 mJ/pulse) has been used to treat a Si surface in different ambient environments, namely vacuum, air and water. We show that ablation threshold and crater characteristics (diameter 'D' and shape of craters) are similar for the three media at low laser fluences, suggesting an identical radiation-related mechanism of material removal. In contrast, at high fluences the characteristic dependence of the crater size D 2(F) in the semi-logarithmic scale becomes non-linear, starting from F = 10, 4 and 2 J/cm2 for vacuum, air and water, respectively, while the shape of craters becomes different for these media. The non-linear phenomena are ascribed to plasma-related ablation effects. Possible mechanisms of material removal are discussed

  1. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

    Directory of Open Access Journals (Sweden)

    Carlo Cagini

    2015-01-01

    Full Text Available The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

  2. Serial femtosecond X-ray diffraction of enveloped virus microcrystals

    Directory of Open Access Journals (Sweden)

    Robert M. Lawrence

    2015-07-01

    Full Text Available Serial femtosecond crystallography (SFX using X-ray free-electron lasers has produced high-resolution, room temperature, time-resolved protein structures. We report preliminary SFX of Sindbis virus, an enveloped icosahedral RNA virus with ∼700 Å diameter. Microcrystals delivered in viscous agarose medium diffracted to ∼40 Å resolution. Small-angle diffuse X-ray scattering overlaid Bragg peaks and analysis suggests this results from molecular transforms of individual particles. Viral proteins undergo structural changes during entry and infection, which could, in principle, be studied with SFX. This is an important step toward determining room temperature structures from virus microcrystals that may enable time-resolved studies of enveloped viruses.

  3. Waveguide fabrication in phosphate glasses using femtosecond laser pulses

    International Nuclear Information System (INIS)

    We report on the response of glass to focused femtosecond (fs) laser pulses during waveguide fabrication in a commercial sodium aluminum phosphate glass (Schott IOG-1). Single-pass longitudinal translation of IOG-1 glass with respect to the focused laser beam at a rate of 20 μm/s and pulse energies of 3.5 μJ results in the formation of two waveguides located on opposite sides of the laser-exposed region, which itself does not guide light. This behavior is different from that of the more widely studied silica glass system. The precise location of the waveguides in IOG-1 glass depends on the relative tilt of the fs laser beam with respect to the sample translation direction. Fluorescence imaging of the modified glass using a confocal microscope setup reveals the formation of color center defects in the exposed region but not within the waveguides

  4. Synchronously pumped femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūte, Karolina; Melnikas, Simas; Kičas, Simonas; Trišauskas, Lukas; Vengelis, Julius; Grigonis, Rimantas; Vengris, Mikas; Sirutkaitis, Valdas

    2015-05-01

    We present results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) with broadband complementary chirped mirror pairs (CMP). The SPOPO based on β-BBO nonlinear crystal is pumped by second harmonic of femtosecond Yb:KGW laser and provides signal pulses tunable over spectral range from 625 to 980 nm. More than 500 mW are generated in the signal beam, giving up to 27 % pump power to signal power conversion efficiency. The plane SPOPO cavity mirror pairs were specially designed to provide 99 % reflection in broad spectral range corresponding to signal wavelength tuning (630-1030 nm) and to suppress group delay dispersion (GDD) oscillations down to +/-10 fs2. Dispersion properties of designed mirrors were tested with white light interferometer (WLI) and attributed to the SPOPO tuning behaviour.

  5. Ferroelectric domain engineering by focused infrared femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xin; Shvedov, Vladlen; Sheng, Yan, E-mail: yan.sheng@anu.edu.au [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Karpinski, Pawel [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Wroclaw University of Technology, Wybrzeze Wyspianskiego, Wroclaw (Poland); Koynov, Kaloian [Max-Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); Wang, Bingxia; Trull, Jose; Cojocaru, Crina [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Rambla Sant Nebridi, 08222 Terrassa, Barcelona (Spain); Krolikowski, Wieslaw [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Texas A& M University at Qatar, Doha (Qatar)

    2015-10-05

    We demonstrate infrared femtosecond laser-induced inversion of ferroelectric domains. This process can be realised solely by using tightly focused laser pulses without application of any electric field prior to, in conjunction with, or subsequent to the laser irradiation. As most ferroelectric crystals like LiNbO{sub 3}, LiTaO{sub 3}, and KTiOPO{sub 4} are transparent in the infrared, this optical poling method allows one to form ferroelectric domain patterns much deeper inside a ferroelectric crystal than by using ultraviolet light and hence can be used to fabricate practical devices. We also propose in situ diagnostics of the ferroelectric domain inversion process by monitoring the Čerenkov second harmonic signal, which is sensitive to the appearance of ferroelectric domain walls.

  6. Filament propagation length of femtosecond pulses with different transverse modes

    CERN Document Server

    Kaya, N; Kaya, G; Strohaber, J; Kolomenskii, A A; Schuessler, H A

    2014-01-01

    We experimentally studied intense femtosecond pulse filamentation and propagation in water for Gaussian, Laguerre-Gaussian, and Bessel-Gaussian incident beams. These different transverse modes for incident laser pulses were created from an initial Gaussian beam by using a computer generated hologram technique. We found that the length of the filament induced by the Bessel-Gaussian incident beam was longer than that for the other transverse modes under the conditions of the same peak intensity, pulse duration, and the size of the central part of the beam. To better understand the Bessel-Gaussian beam propagation, we performed a more detailed study of the filament length as a function of the number of radial modal lobes. The length increased with the number of lobes, implying that the radial modal lobes serve as an energy reservoir for the filament formed by the central intensity peak.

  7. Stochastic Liouville equations for femtosecond stimulated Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Agarwalla, Bijay Kumar; Ando, Hideo; Dorfman, Konstantin E.; Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92617 (United States)

    2015-01-14

    Electron and vibrational dynamics of molecules are commonly studied by subjecting them to two interactions with a fast actinic pulse that prepares them in a nonstationary state and after a variable delay period T, probing them with a Raman process induced by a combination of a broadband and a narrowband pulse. This technique, known as femtosecond stimulated Raman spectroscopy (FSRS), can effectively probe time resolved vibrational resonances. We show how FSRS signals can be modeled and interpreted using the stochastic Liouville equations (SLE), originally developed for NMR lineshapes. The SLE provide a convenient simulation protocol that can describe complex dynamics caused by coupling to collective bath coordinates at much lower cost than a full dynamical simulation. The origin of the dispersive features that appear when there is no separation of timescales between vibrational variations and the dephasing time is clarified.

  8. Serial femtosecond crystallography datasets from G protein-coupled receptors.

    Science.gov (United States)

    White, Thomas A; Barty, Anton; Liu, Wei; Ishchenko, Andrii; Zhang, Haitao; Gati, Cornelius; Zatsepin, Nadia A; Basu, Shibom; Oberthür, Dominik; Metz, Markus; Beyerlein, Kenneth R; Yoon, Chun Hong; Yefanov, Oleksandr M; James, Daniel; Wang, Dingjie; Messerschmidt, Marc; Koglin, Jason E; Boutet, Sébastien; Weierstall, Uwe; Cherezov, Vadim

    2016-01-01

    We describe the deposition of four datasets consisting of X-ray diffraction images acquired using serial femtosecond crystallography experiments on microcrystals of human G protein-coupled receptors, grown and delivered in lipidic cubic phase, at the Linac Coherent Light Source. The receptors are: the human serotonin receptor 2B in complex with an agonist ergotamine, the human δ-opioid receptor in complex with a bi-functional peptide ligand DIPP-NH2, the human smoothened receptor in complex with an antagonist cyclopamine, and finally the human angiotensin II type 1 receptor in complex with the selective antagonist ZD7155. All four datasets have been deposited, with minimal processing, in an HDF5-based file format, which can be used directly for crystallographic processing with CrystFEL or other software. We have provided processing scripts and supporting files for recent versions of CrystFEL, which can be used to validate the data. PMID:27479354

  9. Femtosecond-scale switching based on excited free-carriers

    CERN Document Server

    Sivan, Y; Yuce, E; Mosk, A P

    2015-01-01

    We describe novel optical switching schemes operating at femtosecond time scales by employing free carrier (FC) excitation. Such unprecedented switching times are made possible by spatially patterning the density of the excited FCs. In the first realization, we rely on diffusion, i.e., on the nonlocality of the FC nonlinear response of the semiconductor, to erase the initial FC pattern and, thereby, eliminate the reflectivity of the system. In the second realization, we erase the FC pattern by launching a second pump pulse at a controlled delay. We discuss the advantages and limitations of the proposed approaches and demonstrate their potential applicability for switching ultrashort pulses propagating in silicon waveguides. We show switching efficiencies of up to $50\\%$ for $100$ fs pump pulses, which is an unusually high level of efficiency for such a short interaction time, a result of the use of the strong FC nonlinearity. Due to limitations of saturation and pattern effects, these schemes can be employed ...

  10. Femtosecond Laser Patterning of the Biopolymer Chitosan for Biofilm Formation.

    Science.gov (United States)

    Estevam-Alves, Regina; Ferreira, Paulo Henrique Dias; Coatrini, Andrey C; Oliveira, Osvaldo N; Fontana, Carla Raquel; Mendonca, Cleber Renato

    2016-01-01

    Controlling microbial growth is crucial for many biomedical, pharmaceutical and food industry applications. In this paper, we used a femtosecond laser to microstructure the surface of chitosan, a biocompatible polymer that has been explored for applications ranging from antimicrobial action to drug delivery. The influence of energy density on the features produced on chitosan was investigated by optical and atomic force microscopies. An increase in the hydrophilic character of the chitosan surface was attained upon laser micromachining. Patterned chitosan films were used to observe Staphylococcus aureus (ATCC 25923) biofilm formation, revealing an increase in the biofilm formation in the structured regions. Our results indicate that fs-laser micromachining is an attractive option to pattern biocompatible surfaces, and to investigate basic aspects of the relationship between surface topography and bacterial adhesion. PMID:27548153

  11. High-Resolution Displacement Measurement using a Femtosecond Frequency Comb

    Czech Academy of Sciences Publication Activity Database

    Číp, Ondřej; Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Buchta, Zdeněk; Lazar, Josef

    Düsseldorf: VDI Verlag GmbH, 2011, s. 313-319. ISBN 978-3-18-092156-3. ISSN 0083-5560. [IMEKO Symposium - Laser Metrology for Precision Measurement and Inspection in Industry 2011 /10./. Braunschweig (DE), 12.09.2011-14.09.2011] R&D Projects: GA ČR GP102/09/P293; GA ČR GPP102/11/P819; GA ČR GAP102/10/1813; GA MŠk ED0017/01/01; GA MŠk(CZ) LC06007; GA ČR GP102/09/P630 Institutional research plan: CEZ:AV0Z20650511 Keywords : Fabry-Perot cavity * femtosecond frequency comb Subject RIV: BH - Optics, Masers, Lasers

  12. Femtosecond Studies Of Coulomb Explosion Utilizing Covariance Mapping

    CERN Document Server

    Card, D A

    2000-01-01

    The studies presented herein elucidate details of the Coulomb explosion event initiated through the interaction of molecular clusters with an intense femtosecond laser beam (≥1 PW/cm2). Clusters studied include ammonia, titanium-hydrocarbon, pyridine, and 7-azaindole. Covariance analysis is presented as a general technique to study the dynamical processes in clusters and to discern whether the fragmentation channels are competitive. Positive covariance determinations identify concerted processes such as the concomitant explosion of protonated cluster ions of asymmetrical size. Anti- covariance mapping is exploited to distinguish competitive reaction channels such as the production of highly charged nitrogen atoms formed at the expense of the protonated members of a cluster ion ensemble. This technique is exemplified in each cluster system studied. Kinetic energy analyses, from experiment and simulation, are presented to fully understand the Coulomb explosion event. A cutoff study strongly suggests that...

  13. Generating long sequences of high-intensity femtosecond pulses.

    Science.gov (United States)

    Bitter, M; Milner, V

    2016-02-01

    We present an approach to creating pulse sequences extending beyond 150 ps in duration, comprised of 100 μJ femtosecond pulses. A quarter of the pulse train is produced by a high-resolution pulse shaper, which allows full controllability over the timing of each pulse. Two nested Michelson interferometers follow to quadruple the pulse number and the sequence duration. To boost the pulse energy, the long train is sent through a multipass Ti:sapphire amplifier, followed by an external compressor. A periodic sequence of 84 pulses of 120 fs width and an average pulse energy of 107 μJ, separated by 2 ps, is demonstrated as a proof of principle. PMID:26836087

  14. Femtosecond laser generated gold nanoparticles and their plasmonic properties

    Science.gov (United States)

    Das, Rupali; Navas M., P.; Soni, R. K.

    2016-05-01

    The pulsed laser ablation in liquid medium is now commonly used to generate stable colloidal nanoparticles (NPs) in absence of any chemical additives or stabilizer with diverse applications. In this paper, we report generation of gold NPs (Au NPs) by ultra-short laser pulses. Femtosecond (fs) laser radiation (λ = 800 nm) has been used to ablate a gold target in pure de-ionized water to produce gold colloids with smallsize distribution. The average size of the particles can be further controlled by subjecting to laser-induced post-irradiation providing a versatile physical method of size-selected gold nanoparticles. The optical extinction and morphological dimensions were investigated with UV-Vis spectroscopy and Transmission Electron Microscopy measurements, respectively. Finite difference time domain (FDTD) method is employed to calculate localized surface plasmon (LSPR) wavelength and the near-field generated by Au NPs and their hybrids.

  15. Femtosecond nonlinear ultrasonics in gold probed with ultrashort surface plasmons

    CERN Document Server

    Temnov, Vasily V; Nelson, Keith A; Thomay, Tim; Knittel, Vanessa; Leitenstorfer, Alfred; Makarov, Denys; Albrecht, Manfred; Bratschitsch, Rudolf

    2013-01-01

    Fundamental interactions induced by lattice vibrations on ultrafast time scales become increasingly important for modern nanoscience and technology. Experimental access to the physical properties of acoustic phonons in the THz frequency range and over the entire Brillouin zone is crucial for understanding electric and thermal transport in solids and their compounds. Here, we report on the generation and nonlinear propagation of giant (1 percent) acoustic strain pulses in hybrid gold/cobalt bilayer structures probed with ultrafast surface plasmon interferometry. This new technique allows for unambiguous characterization of arbitrary ultrafast acoustic transients. The giant acoustic pulses experience substantial nonlinear reshaping already after a propagation distance of 100 nm in a crystalline gold layer. Excellent agreement with the Korteveg-de Vries model points to future quantitative nonlinear femtosecond THz-ultrasonics at the nano-scale in metals at room temperature.

  16. Hole drilling on glass optical fibers by a femtosecond laser

    Science.gov (United States)

    Hamasaki, Masayuki; Gouya, Kenji; Watanabe, Kazuhiro

    2012-01-01

    A novel optical fiber sensor has been developed for gaseous material detection by means of a femto-second laser which has ultrashort pulse and ultrahigh peak power. This sensor has attractive sensor potion consisted of drilling holes array which is machined on the glass optical fiber. Additionally, the sensor potion is coated with thin gold film. This work expects that an interaction could be induced between transmitted light through fiber core and a bottom of the drilled holes which reaches the fiber core. The interaction could induce near-field optical phenomenon excited by transmitted light through the fiber core. This scheme could make it possible to detect gaseous-material phase substances around the optical fiber. In this study, we found that localized surface plasmon (LSP) was excited by the transmitted light through the fiber core. This paper shows experiment to obtain optimum irradiation conditions and investigation for sensor principle for the development of a novel fiber sensor.

  17. Femtosecond laser pulse train interaction with dielectric materials

    Science.gov (United States)

    Dematteo Caulier, O.; Mishchik, K.; Chimier, B.; Skupin, S.; Bourgeade, A.; Javaux Léger, C.; Kling, R.; Hönninger, C.; Lopez, J.; Tikhonchuk, V.; Duchateau, G.

    2015-11-01

    The interaction of trains of femtosecond microjoule laser pulses with dielectric materials by means of a multi-scale model is investigated. Theoretical predictions are directly confronted with experimental observations in soda-lime glass. It is shown that due to the low heat conductivity, a significant fraction of the laser energy can be accumulated in the absorption region. Depending on the pulse repetition rate, the material can be heated to high temperatures even though the single pulse energy is too low to induce a significant material modification. Regions heated above the glass transition temperature in the simulations correspond very well to zones of permanent material modifications observed in the experiments. It turns out that pulse-to-pulse variations of the laser absorption are negligible and of minor influence to permanent material modifications.

  18. Terahertz waves radiated from two noncollinear femtosecond plasma filaments

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko, E-mail: otani@riken.jp [Terahertz Sensing and Imaging Research Team, RIKEN Center for Advanced Photonics, RIKEN, Sendai, Miyagi 980-0845 (Japan); Midorikawa, Katsumi [Attosecond Science Research Team, RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan)

    2015-11-23

    Terahertz (THz) waves radiated from two noncollinear femtosecond plasma filaments with a crossing angle of 25° are investigated. The irradiated THz waves from the crossing filaments show a small THz pulse after the main THz pulse, which was not observed in those from single-filament scheme. Since the position of the small THz pulse changes with the time-delay of two filaments, this phenomenon can be explained by a model in which the small THz pulse is from the second filament. The denser plasma in the overlap region of the filaments changes the movement of space charges in the plasma, thereby changing the angular distribution of THz radiation. As a result, this schematic induces some THz wave from the second filament to propagate along the path of the THz wave from the first filament. Thus, this schematic alters the direction of the THz radiation from the filamentation, which can be used in THz wave remote sensing.

  19. Nanostructuring of ITO thin films through femtosecond laser ablation

    Science.gov (United States)

    Sahin, Ramazan; Kabacelik, Ismail

    2016-04-01

    Due to reduced thermal effects, tightly focused femtosecond laser beams can yield submicron resolution with minimal side effects. In laser direct writing applications, diffraction-free nature of the Bessel beams relaxes alignment of the sample and shortens the production time. Micron-sized central spots and long depth of focused beams can be simultaneously produced. We apply fs Bessel beam single-pulse ablation method to transparent conductive oxide films. We use laser of 1030 nm wavelength and two different axicons (base angles are 25° and 40°). Fabricated structures are characterized by optical microscope, atomic force microscope and scanning electron microscope. Laser beam shaping and virtues of non-diffracted Bessel beams provide periodic structures for scribing in the solar cells or high-resolution displays and reduce the process time.

  20. Femtosecond laser-induced surface structures on carbon fibers.

    Science.gov (United States)

    Sajzew, Roman; Schröder, Jan; Kunz, Clemens; Engel, Sebastian; Müller, Frank A; Gräf, Stephan

    2015-12-15

    The influence of different polarization states during the generation of periodic nanostructures on the surface of carbon fibers was investigated using a femtosecond laser with a pulse duration τ=300  fs, a wavelength λ=1025  nm, and a peak fluence F=4  J/cm². It was shown that linear polarization results in a well-aligned periodic pattern with different orders of magnitude concerning their period and an alignment parallel and perpendicular to fiber direction, respectively. For circular polarization, both types of uniform laser-induced periodic surface structures (LIPSS) patterns appear simultaneously with different dominance in dependence on the position at the fiber surface. Their orientation was explained by the polarization-dependent absorptivity and the geometrical anisotropy of the carbon fibers. PMID:26670499

  1. Sunlight loss for femtosecond microstructured silicon with two impurity bands

    International Nuclear Information System (INIS)

    Black silicon, produced by irradiating the surface of a silicon wafer with femtosecond laser pulses in the presence of a sulfur-bearing gas, is widely believed to be a potential material for efficient multi-intermediate-band silicon solar cells. Taking chalcogen as an example, we analyse the loss of sunlight for silicon with two impurity bands and we find that loss of the sunlight can be minimized to 0.332 when Te0(0.307 eV) and Te+(0.411 eV) are doped into microstructured silicon. Finally, problems needed to be resolved in analysing the relationship between conversion efficiency of the ideal four-band silicon solar cell and the position of the introduced two intermediated bands in silicon according to detailed balance theory are pointed out with great emphasis. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  2. Femtosecond Laser Micromachining Photonic and Microfluidic Devices in Transparent Materials

    CERN Document Server

    Cerullo, Giulio; Ramponi, Roberta

    2012-01-01

    Femtosecond laser micromachining of transparent material is a powerful and versatile technology. In fact, it can be applied to several materials. It is a maskless technology that allows rapid device prototyping, has intrinsic three-dimensional capabilities and can produce both photonic and microfluidic devices. For these reasons it is ideally suited for the fabrication of complex microsystems with unprecedented functionalities. The book is mainly focused on micromachining of transparent materials which, due to the nonlinear absorption mechanism of ultrashort pulses, allows unique three-dimensional capabilities and can be exploited for the fabrication of complex microsystems with unprecedented functionalities.This book presents an overview of the state of the art of this rapidly emerging topic with contributions from leading experts in the field, ranging from principles of nonlinear material modification to fabrication techniques and applications to photonics and optofluidics.

  3. Computer-generated volume holograms fabricated by femtosecond laser micromachining.

    Science.gov (United States)

    Cai, Wenjian; Reber, Theodore J; Piestun, Rafael

    2006-06-15

    We define computer-generated volume holograms (CGVHs) as arbitrary 3D refractive index modulations designed to perform optical functions based on diffraction, scattering, and interference phenomena. CGVHs can differ dramatically from classical volume holograms in terms of coding possibilities, and from thin computer-generated holograms in terms of efficiency and selectivity. We propose an encoding technique for designing such holograms and demonstrate the concept by scanning focused femtosecond laser pulses to produce localized refractive index modifications in glass. These CGVHs show a significant increase in efficiency with thickness. Consequently, they are attractive for photonic integration with free-space and guided-wave devices, as well as for encoding spatial and temporal information. PMID:16729087

  4. Parametric study on femtosecond laser pulse ablation of Au films

    International Nuclear Information System (INIS)

    Ablation process of 1 kHz rate femtosecond lasers (pulse duration 148 fs, wavelength 775 nm) with Au films on silica substrates has been systemically studied. The single-pulse threshold can be obtained directly. For the multiple pulses the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect. From the plot of accumulated laser fluence N x φ th(N) and the number of laser pulses N, incubation coefficient of Au film can be obtained (s = 0.765). As the pulse energy is increased, the single pulse ablation rate is increasing following two ablation logarithmic regimes, which can be explained by previous research

  5. Femtosecond photoelectron and photoion spectrometer with vacuum ultraviolet probe pulses

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Markus, E-mail: markus.koch@tugraz.at [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria); Wolf, Thomas J.A. [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Grilj, Jakob [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne EPFL, 1015 (Switzerland); Sistrunk, Emily [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Gühr, Markus, E-mail: mguehr@slac.stanford.edu [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

    2014-12-15

    Highlights: • We perform time resolved spectroscopy with vacuum ultraviolet (VUV) light. • We measure photoions and photoelectrons for different UV excitation VUV probe delays. • The VUV pulses are created by high harmonic generation. • We filter out a small band from the high harmonic comb using an indium filter. - Abstract: We describe a femtosecond photoelectron and photoion spectroscopy setup using a simple, novel way to produce a vacuum ultraviolet (VUV) probe pulse. We isolate the femtosecond VUV pulse from a high harmonic continuum by using the bandpass characteristics of a thin indium (In) metal filter. The filter transmits the 9th harmonic of the 800 nm laser corresponding to a wavelength of 89 nm (hν = 14 eV). The 9th harmonic is obtained with high conversion efficiencies and has sufficient photon energy to access the complete set of valence electron levels in most molecules. Compared to using grating monochromators, the filter strategy does not change the length of VUV pulse. The setup also allows for direct comparison of VUV single-photon probe with 800 nm multi-photon probe without influencing the delay of excitation and probe pulse or the beam geometry. We use a magnetic bottle spectrometer with high collection efficiency for electrons, serving at the same time as a time of flight spectrometer for ions. Characterization measurements on Xe reveal the spectral width of the 9th harmonic to be 190 ± 60 meV and a photon flux of ∼1 ×10{sup 7} photons/pulse after spectral filtering. As a first application, we investigate the S{sub 1} excitation of perylene using time-resolved ion spectra obtained with multiphoton probing and time-resolved electron spectra from VUV single-photon probing. The time resolution extracted from cross-correlation measurements is 65 ± 10 fs for both probing schemes and the pulse duration of the 9th harmonic is found to be 35 ± 8 fs.

  6. New technology update: femtosecond laser in cataract surgery

    Directory of Open Access Journals (Sweden)

    Nagy ZZ

    2014-06-01

    Full Text Available Zoltan Z NagyDepartment of Ophthalmology, Semmelweis University, Budapest, HungaryAbstract: Femtosecond lasers represent a new frontier in cataract surgery. Since their ­introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented regarding capsulotomy, fragmentation of the crystalline lens, corneal wound creation, and refractive results. Safety issues such as endothelial and macular changes are also discussed. The most important advantage of femtolaser cataract technology at present is that all the important surgical steps of cataract surgery can be planned and customized, delivering unparalleled accuracy, repeatability, and consistency in surgical results. The advantages of premium lenses can be maximally used in visual and presbyopia restoration as well. The advantages of ­premium lenses can be maximally used, not only in visual, but in presbyopia restoration as well. Quality of vision can be improved with less posterior chamber lens (PCL tilt, more centralized position of the PCL, possibly less endothelial damage, less macular edema, and less posterior capsule opacification (PCO formation. This technological achievement should be followed by other technical developments in the lens industry. Hopefully this review article will help us to understand the technology and the results to ­demonstrate the differences between the use of femtolasers and phacoemulsification-based cataract surgery. The most important data of the literature are summarized to show ophthalmologists the benefits of the technology in order to provide the best refractive results to the patient.Keywords: femtosecond laser-assisted cataract surgery, capsulotomy, lens fragmentation, corneal wound, arcuate keratotomy, safety

  7. Simulation of condensed matter dynamics in strong femtosecond laser pulses

    International Nuclear Information System (INIS)

    Ultrashort custom-tailored laser pulses can be employed to observe and control the motion of electrons in atoms and small molecules on the (sub-) femtosecond time scale. Very recently, efforts are underway to extend these concepts to solid matter. This monograph theoretically explores first applications of electron control by ultrashort laser pulses in three paradigmatic systems of solid-state density: a metal nano-structure (nanometric metal tip), a bulk dielectric (quartz glass), and the buckminsterfullerene molecule (C60) as arguably the smallest possible nano-particle. The electron motion is resolved on the atomic length and time scale by ab-initio simulations based on time-dependent density functional theory. Our quantum simulations are complemented by classical and semi-classical models elucidating the underlying mechanisms. We compare our results to experiments where already available and find good agreement. With increasing laser intensity, we find a transition from vertical photoexcitation to tunneling-like excitation. For nanostructures, that leads to temporally confined electron photoemission and thereby to quantum interferences in the energy spectra of emitted electrons. Similarly, tunneling can be induced between neighboring atoms inside an insulator. This provides a mechanism for ultrafast light-field controlled currents and modification of the optical properties of the solid, promising to eventually realize light-field electronic devices operating on the femtosecond time scale and nanometer length scale. Electron-electron interaction leads to near field enhancement and spatial localization of the non-linear response and is investigated both classically by solving the Maxwell equations near a nanostructure as well as quantum mechanically for the fullerene molecule. For the latter, we discuss scrutiny of the molecular near-field by the attosecond streaking technique. Our results demonstrate that ultrashort laser pulses can be employed to steer the

  8. Industry-grade high average power femtosecond light source

    Science.gov (United States)

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

    2014-03-01

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

  9. Femtosecond laser enhanced current in a thermionic diode with barium vapor

    International Nuclear Information System (INIS)

    We studied the signal from a thermionic diode when a femtosecond laser beam was spatially overlapped by an excimer pumped dye laser beam. The nanosecond dye laser was scanned from 435 to 438 nm in order to excite the autoionizing levels of barium by two photon absorption. The broadband ultrashort laser light was centered at 427 nm, which is also above the first ionization limit of barium. The bias voltage between the cell body and the tungsten rod (set at either 9 or 0 V) was used to collect electrons after the barium ions had been created by multiphoton (auto) ionization. The overall background of the thermionic signal was appreciably elevated due to the two photon ionization by the broadband femtosecond laser. We measured the thermionic signal with and without femtosecond laser overlap, and with a biasless and biased thermionic diode. The effect of the femtosecond laser was appreciable enhancement of the background ionization continuum. This was especially visible in the presence of noble gases at pressure of 50 mbar. Argon produced the largest and helium produced the smallest enhancement in the background continuum. In addition, we observed a few broad spectral features of a presumably collision induced nature. - Highlights: • Femtosecond laser beam spatially overlapped by excimer pumped dye laser beam. • The nanosecond dye laser scanned from 435 to 438 nm for two photon absorption. • Thermionic signal detection of Ba autoionizing levels. • The femtosecond laser enhanced the background ionization continuum. • Broad spectral features of presumably collision induced nature have been observed

  10. Fast femtosecond laser ablation for efficient cutting of sintered alumina substrates

    Science.gov (United States)

    Oosterbeek, Reece N.; Ward, Thomas; Ashforth, Simon; Bodley, Owen; Rodda, Andrew E.; Simpson, M. Cather

    2016-09-01

    Fast, accurate cutting of technical ceramics is a significant technological challenge because of these materials' typical high mechanical strength and thermal resistance. Femtosecond pulsed lasers offer significant promise for meeting this challenge. Femtosecond pulses can machine nearly any material with small kerf and little to no collateral damage to the surrounding material. The main drawback to femtosecond laser machining of ceramics is slow processing speed. In this work we report on the improvement of femtosecond laser cutting of sintered alumina substrates through optimisation of laser processing parameters. The femtosecond laser ablation thresholds for sintered alumina were measured using the diagonal scan method. Incubation effects were found to fit a defect accumulation model, with Fth,1=6.0 J/cm2 (±0.3) and Fth,∞=2.5 J/cm2 (±0.2). The focal length and depth, laser power, number of passes, and material translation speed were optimised for ablation speed and high quality. Optimal conditions of 500 mW power, 100 mm focal length, 2000 μm/s material translation speed, with 14 passes, produced complete cutting of the alumina substrate at an overall processing speed of 143 μm/s - more than 4 times faster than the maximum reported overall processing speed previously achieved by Wang et al. [1]. This process significantly increases processing speeds of alumina substrates, thereby reducing costs, making femtosecond laser machining a more viable option for industrial users.

  11. Transverse writing of three-dimensional tubular optical waveguides in glass with a slit-shaped femtosecond laser beam

    Science.gov (United States)

    Liao, Yang; Qi, Jia; Wang, Peng; Chu, Wei; Wang, Zhaohui; Qiao, Lingling; Cheng, Ya

    2016-01-01

    We report on fabrication of tubular optical waveguides buried in ZBLAN glass based on transverse femtosecond laser direct writing. Irradiation in ZBLAN with focused femtosecond laser pulses leads to decrease of refractive index in the modified region. Tubular optical waveguides of variable mode areas are fabricated by forming the four sides of the cladding with slit-shaped femtosecond laser pulses, ensuring single mode waveguiding with a mode field dimension as small as ~4 μm. PMID:27346285

  12. Transverse writing of three-dimensional tubular optical waveguides in glass with slit-shaped femtosecond laser beams

    CERN Document Server

    Liao, Yang; Wang, Peng; Chu, Wei; Wang, Zhaohui; Qiao, Lingling; Cheng, Ya

    2016-01-01

    We report on fabrication of tubular optical waveguides buried in ZBLAN glass based on transverse femtosecond laser direct writing. Irradiation in ZBLAN with focused femtosecond laser pulses leads to decrease of refractive index in the modified region. Tubular optical waveguides of variable mode areas are fabricated by forming the four sides of the cladding with slit-shaped femtosecond laser pulses, ensuring single mode waveguiding with a mode field dimension compatible with direct coupling to single-mode optical fibers.

  13. Femtosecond laser 3D micromachining: a powerful tool for the fabrication of microfluidic, optofluidic, and electrofluidic devices based on glass.

    Science.gov (United States)

    Sugioka, Koji; Xu, Jian; Wu, Dong; Hanada, Yasutaka; Wang, Zhongke; Cheng, Ya; Midorikawa, Katsumi

    2014-09-21

    Femtosecond lasers have unique characteristics of ultrashort pulse width and extremely high peak intensity; however, one of the most important features of femtosecond laser processing is that strong absorption can be induced only at the focus position inside transparent materials due to nonlinear multiphoton absorption. This exclusive feature makes it possible to directly fabricate three-dimensional (3D) microfluidic devices in glass microchips by two methods: 3D internal modification using direct femtosecond laser writing followed by chemical wet etching (femtosecond laser-assisted etching, FLAE) and direct ablation of glass in water (water-assisted femtosecond laser drilling, WAFLD). Direct femtosecond laser writing also enables the integration of micromechanical, microelectronic, and microoptical components into the 3D microfluidic devices without stacking or bonding substrates. This paper gives a comprehensive review on the state-of-the-art femtosecond laser 3D micromachining for the fabrication of microfluidic, optofluidic, and electrofluidic devices. A new strategy (hybrid femtosecond laser processing) is also presented, in which FLAE is combined with femtosecond laser two-photon polymerization to realize a new type of biochip termed the ship-in-a-bottle biochip. PMID:25012238

  14. Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

    DEFF Research Database (Denmark)

    Poli, F.; Lægsgaard, Jesper; Passaro, D.;

    2009-01-01

    higher-order mode (HOM), stressing the difference between their spatial distributions, with respect to the uniform refractive index core. In the present analysis a rod-type PCF with a 19-missing air-hole core, whose radius is 30 mum, has been considered. Initially, a PCF step-index model has been applied...... a forward-pumped configuration....

  15. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    CERN Document Server

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  16. Theory of noise in a kilo-Hz cascaded high-energy Yb-doped nanosecond pulsed fiber amplifier

    International Nuclear Information System (INIS)

    A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio (SNR) analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

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

    OpenAIRE

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

    2010-01-01

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

  18. Spatially selective Er/Yb-doped CaF2 crystal formation by CO2 laser exposure

    International Nuclear Information System (INIS)

    Highlights: • Oxyfluoride glass–ceramics containing CaF2 nanocrystals doped with Er3+ and Yb3+ ions were formed on the glass surface by CO2 laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF2 nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO2 laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF2 and miner Ca2SiO4 nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment

  19. High-peak-power second-harmonic generation of single-stage Yb-doped fiber amplifiers

    Science.gov (United States)

    Horiuchi, Ryusuke; Saiki, Koichi; Adachi, Koji; Tei, Kazuyoku; Yamaguchi, Shigeru

    2008-05-01

    A high-peak-power and high-repetition-rate fiber laser architecture is successfully demonstrated using a single-stage fiber amplifier. Nonlinear optical effects in a fiber amplifier degrade the monochromaticity of amplified laser pulses. In general, it is difficult for a non-monochromatic laser pulse to realize high-order harmonic generation with bulk nonlinear optical crystals. To overcome this problem, a single-stage amplifier architecture and a gain fiber with a high cladding absorption coefficient are employed. Furthermore, single-stage amplification enables the use of a multi-longitudinal mode electro-optically (EO) Q-switched micro seed laser. This architecture can generate a peak power of 100 kW at 50 kHz and an average power of 10 W. A second-harmonic conversion efficiency of 51% is obtained using this architecture and a LiB3O5 (LBO) crystal.

  20. Mode-locked Yb-doped all-fiber laser based on in-fiber acoustooptic modulation

    International Nuclear Information System (INIS)

    We show what we believe is the first demonstration of an ytterbium-doped strictly all-fiber active mode-locking laser. The active control of the laser is based on in-fiber amplitude modulation at 11 MHz, which is achieved by using an all-fiber acoustooptic superlattice modulator driven by standing acoustic waves. In our experiments, the laser was operated at 1091.3 nm and had two stable regimes producing either a train of mode-locked single pulses or a train of pulse pairs. Best results for the mode-locked train of single pulses were 740 ps of time width and 26 mW of average power, at a pump power of 480 mW

  1. Thermal effect-resilient design of large mode area double-cladding Yb-doped photonic crystal fibers

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Johansen, Mette Marie;

    2013-01-01

    on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to...

  2. Thermal effect-resilient design of large mode area double-cladding Yb-doped photonic crystal fibers

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Johansen, Mette Marie; Alkeskjold, Thomas Tanggaard; Leick, Lasse; Broeng, Jes; Sozzi, Michele; Candiani, Alessandro; Cucinotta, Annamaria; Selleri, Stefano

    2013-01-01

    The effects of thermally-induced refractive index change on the guiding properties of different large mode area fibers have been numerically analyzed. A simple but accurate model has been applied to obtain the refractive index change in the fiber cross-section, and a full-vector modal solver based...... on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to...... thermal effects....

  3. Superconductivity at 31.3 K in Yb-doped La(O/F)FeAs superconductors

    Indian Academy of Sciences (India)

    J Prakash; S J Singh; S Patnaik; A K Ganguli

    2010-01-01

    The effect of ytterbium substitution at the lanthanum site on the superconducting properties of La1-YbO0.8F0.2FeAs ( = 0.10, 0.20 and 0.30) oxypnictides has been investigated. Powder X-ray diffraction studies show the presence of Yb2O3 and LaOF as secondary phases. The superconducting transition temperature (c) of 31.3 (± 0.05) K has been observed in = 0.1 composition which is the maximum c so far in the La(O/F)FeAs superconductor family at ambient pressure. Further increase in leads to suppression and broadening of superconducting transition. The resistive transition curves under different magnetic fields were investigated, leading to determination of upper critical field c2 () of this new superconductor. The value of c2 at zero temperature is estimated to be about 46 T corresponding to coherence length ∼ 27 Å.

  4. Luminance Conversion Property of Er and Yb Doped KZnF3 Nanocrystal Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Weidong Lai

    2015-01-01

    Full Text Available In order to make full use of exposure energy, one feasible way is to modify the luminance of crystal by rare earth doping technique. KZnF3:Er3+ and KZnF3:Er3+/Yb3+ nanocrystals of uniform cuboid perovskite type morphology, with average diameter of 130 nm, has been synthesized by hydrothermal method. When Yb3+ ions were codoped with Er3+, absorption peak at 970 nm has been heightened and widened, and the photon absorption cross section increased. The common xenon lamp exposure cannot initiate obvious nonlinear phenomenon of the doped Er3+ and Yb3+, and exposing at 245 nm only excites the fluorescence around 395 nm. Contrarily, under high power IR exposure at 980 nm, obvious upconversion photoluminescence (PL has been observed due to the two-photon process. The PL mechanism of the doped Er3+ ion in KZnF3:Er3+/Yb3+ nanocrystals is confirmed. Furthermore, Yb3+ codoped as sensitizer has modified the PL intensity of Er3+ from green light range to red range, and the primary channel is changed from 4S3/2(Er3+ → 4I15/2(Er3+ of only Er3+ doped KZnF3 nanocrystal to 4F9/2(Er3+ → 4I15/2(Er3+ of Er3+/Yb3+ codoped sample. With exposure energy increasing, such primary transition channel after two-photon excitation is unchanged.

  5. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    International Nuclear Information System (INIS)

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power. (letter)

  6. Femtosecond laser processing of photovoltaic and transparent materials

    Science.gov (United States)

    Ahn, Sanghoon

    The photovoltaic semiconducting and transparent dielectric materials are of high interest in current industry. Femtosecond laser processing can be an effective technique to fabricate such materials since non-linear photochemical mechanisms predominantly occur. In this series of studies, femtosecond (fs) laser processing techniques that include laser drilling on Si wafer, laser scribing on CIGS thin film, laser ablation on Lithium Niobate (LN) crystal, and fabrication of 3D structures in fused silica were studied. The fs laser drilling on Si wafer was performed to fabricate via holes for wrap-through PV devices. For reduction of the number of shots in fs laser drilling process, self-action of laser light in the air was initiated. To understand physical phenomena during laser drilling, scanning electron microscopy (SEM), emission, and shadowgraph images were studied. The result indicated the presence of two mechanisms that include fabrication by self-guided beam and wall-guided beam. Based on our study, we could fabricate ~16 micrometer circular-shaped via holes with ~200 laser pulses on 160-170 micrometer thick c- and mc-Si wafer. For the fs laser scribing on ink jet printed CIGS thin film solar cell, the effect of various parameters that include pulse accumulation, wavelength, pulse energy, and overlapping were elucidated. In our processing regime, the effect of wavelength could be diminished due to compensation between beam size, pulse accumulation, energy fluence, and the absorption coefficient. On the other hand, for high PRF fs laser processing, pulse accumulation effect cannot be ignored, while it can be negligible in low PRF fs laser processing. The result indicated the presence of a critical energy fluence for initiating delamination of CIGS layer. To avoid delamination and fabricate fine isolation lines, the overlapping method can be applied. With this method, ~1 micrometer width isolation lines were fabricated. The fs laser ablation on LN wafer was studied

  7. Femtosecond laser FLEx surgery — first experience of application

    Directory of Open Access Journals (Sweden)

    O.A. Kostin

    2013-01-01

    Full Text Available ABSTRACT Purpose. A comparative estimation of the thickness of corneal flap formed with Moria microkeratome and VisuMax femtosecond laser as well as refraction, visual acuity, changes of contrast sensitivity and higher order aberrations after LASIK and FLEx for myopia and myopic astigmatism correction. Material and methods. Two groups of patients, 70 eyes in each were investigated. In the group 1 the standard LASIK was performed. In the group 2 the FLEx was carried out. Besides standard investigations, in both groups wavefront aberrations were measured before operation and 1 month later in Malacara notation with WASCA aberrometer (Carl Zeiss Meditec, Germany with a non-medicamentous pupil diameter of 6mm. Flap thickness measurement in the center of the cornea and 1, 2 and 3mm from the center was performed in both groups with the Visante OCT (Carl Zeiss Meditec in High Resolution Corneal Quad and High Resolution Corneal Single modes. Contrast sensitivity was measured in both groups with CSV-1000 unit (VECTORVISION. Follow-up period was 1 month. Results. Uncorrected visual acuity before surgery in groups 1 and 2 was 0.05±0.07; 0.06±0.02 and made after the operation 0.99±0.05; 0.95±0.09 (p>0.05. Spheric equivalent before surgery in groups 1 and 2 was -4.13±2.08 D; -3.78±1.47 D and after surgery became 0.02±0.16 D; 0.03±0.14 D (p>0.05. Corrected visual acuity before surgery in groups 1 and 2 was 0.98±0.05; 0.99±0.02 and made 0.99±0.07; 0.98±0.04 after surgery (p>0.05. The RMS HO before surgery in groups 1 and 2 was 0.18±0.07 µm, 0.17±0.09 µm and increased after surgery up to 0.37±0.11 µm, 0.29±0.07 µm (p<0.05. Spheric aberration value in groups 1 and 2 before surgery was -0.12±0.19 µm; -0.11±0.15 µm, after surgery it increased negatively in both groups up to -0.53±0.30 µm; -0.24±0.28 µm (p<0.05. Conclusions. 1. Laser femtosecond microkeratome VisuMax allows FLEx without excimer laser. 2. Laser femtosecond microkeratome

  8. Femtosecond structural dynamics on the atomic length scale

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongfang

    2014-03-15

    This thesis reports on the development and application of two different but complementary ultrafast electron diffraction setups built at the Max Planck Research Department for Structural Dynamics. One is an ultra-compact femtosecond electron diffraction (FED) setup (Egun300), which is currently operational (with a maximum electron energy of 150 keV) and provides ultrashort (∝300 fs) and bright (∝10 e/μm{sup 2}) electron bunches. The other one, named as Relativistic Electron Gun for Atomic Exploration (REGAE) is a radio frequency driven 2 to 5 MeV FED setup built in collaboration with different groups from DESY. REGAE was developed as a facility that will provide high quality diffraction with sufficient coherence to even address structural protein dynamics and with electron pulses as short as 20 fs (FWHM). As one of the first students in Prof. R.J. Dwayne Miller's group, I led the femtosecond (fs) laser sub-group at REGAE being responsible for the construction of different key optical elements required to drive both of aforementioned FED systems. A third harmonic generation (THG) and a nonlinear optical parametric amplifier (NOPA) have been used for the photo-generation of ultrashort electron bursts as well as sample laser excitation. Different diagnostic tools have been constructed to monitor the performance of the fs optical system. A fast autocorrelator was developed to provide on the fly pulse duration correction. A transient-grating frequency-resolved optical gating (TG-FROG) was built to obtain detail information about the characteristics of fs optical pulse, i.e. phase and amplitude of its spectral components. In addition to these optical setups, I developed a fs optical pump-probe system, which supports broadband probe pulses. This setup was successfully applied to investigate the semiconductor-to-metal photoinduced phase transition in VO{sub 2} and the ultrafast photo-reduction mechanism of graphene oxide. In regard to FED setups, I have been

  9. Femtosecond structural dynamics on the atomic length scale

    International Nuclear Information System (INIS)

    This thesis reports on the development and application of two different but complementary ultrafast electron diffraction setups built at the Max Planck Research Department for Structural Dynamics. One is an ultra-compact femtosecond electron diffraction (FED) setup (Egun300), which is currently operational (with a maximum electron energy of 150 keV) and provides ultrashort (∝300 fs) and bright (∝10 e/μm2) electron bunches. The other one, named as Relativistic Electron Gun for Atomic Exploration (REGAE) is a radio frequency driven 2 to 5 MeV FED setup built in collaboration with different groups from DESY. REGAE was developed as a facility that will provide high quality diffraction with sufficient coherence to even address structural protein dynamics and with electron pulses as short as 20 fs (FWHM). As one of the first students in Prof. R.J. Dwayne Miller's group, I led the femtosecond (fs) laser sub-group at REGAE being responsible for the construction of different key optical elements required to drive both of aforementioned FED systems. A third harmonic generation (THG) and a nonlinear optical parametric amplifier (NOPA) have been used for the photo-generation of ultrashort electron bursts as well as sample laser excitation. Different diagnostic tools have been constructed to monitor the performance of the fs optical system. A fast autocorrelator was developed to provide on the fly pulse duration correction. A transient-grating frequency-resolved optical gating (TG-FROG) was built to obtain detail information about the characteristics of fs optical pulse, i.e. phase and amplitude of its spectral components. In addition to these optical setups, I developed a fs optical pump-probe system, which supports broadband probe pulses. This setup was successfully applied to investigate the semiconductor-to-metal photoinduced phase transition in VO2 and the ultrafast photo-reduction mechanism of graphene oxide. In regard to FED setups, I have been deeply involved in

  10. Optical measurement on quantum cascade lasers using femtosecond pulses

    Science.gov (United States)

    Cai, Hong

    Quantum cascade lasers (QCLs) as the state-of-the-art mid-infrared (mid-IR) coherent sources have been greatly developed in aspects such as output power, energy efficiency and spectral purity. However, there are additional applications of QCLs in high demand, namely mode-locking, mid-IR modulation, etc. The inherent optical properties and ultrafast carrier dynamics can lead to solutions to these challenges. In this dissertation, we further characterize QCLs using mid-IR femtosecond (fs) pulses generated from a laser system consisting of a Ti:sapphire oscillator, a Ti:sapphire regenerative amplifier, an optical parametric amplifier and a difference frequency generator. We study the Kerr nonlinearity of QCLs by coupling resonant and off-resonant mid-IR fs pulses into an active QCL waveguide. We observe an increase in the spectral width of the transmitted fs pulses as the coupled mid-IR pulse power increases. This is explained by the self-phase modulation effect due to the large Kerr nonlinearity of QCL waveguides. We further confirm this effect by observing the intensity dependent far-field profile of the transmitted mid-IR pulses, showing the pulses undergo self-focusing as they propagate through the active QCL due to the intensity dependent refractive index. The finite-difference time-domain simulations of QCL waveguides with Kerr nonlinearity incorporated show similar behavior to the experimental results. The giant Kerr nonlinearity investigated here may be used to realize ultrafast pulse generation in QCLs. In addition, we temporally resolved the ultrafast mid-infrared transmission modulation of QCLs using a near-infrared pump/mid-infrared probe technique at room temperature. Two different femtosecond wavelength pumps are used with photon energy above and below the quantum well (QW) bandgap. The shorter wavelength pump modulates the mid-infrared probe transmission through interband transition assisted mechanisms, resulting in a high transmission modulation depth

  11. Profitability analysis of a femtosecond laser system for cataract surgery using a fuzzy logic approach

    Science.gov (United States)

    Trigueros, José Antonio; Piñero, David P; Ismail, Mahmoud M

    2016-01-01

    AIM To define the financial and management conditions required to introduce a femtosecond laser system for cataract surgery in a clinic using a fuzzy logic approach. METHODS In the simulation performed in the current study, the costs associated to the acquisition and use of a commercially available femtosecond laser platform for cataract surgery (VICTUS, TECHNOLAS Perfect Vision GmbH, Bausch & Lomb, Munich, Germany) during a period of 5y were considered. A sensitivity analysis was performed considering such costs and the countable amortization of the system during this 5y period. Furthermore, a fuzzy logic analysis was used to obtain an estimation of the money income associated to each femtosecond laser-assisted cataract surgery (G). RESULTS According to the sensitivity analysis, the femtosecond laser system under evaluation can be profitable if 1400 cataract surgeries are performed per year and if each surgery can be invoiced more than $500. In contrast, the fuzzy logic analysis confirmed that the patient had to pay more per surgery, between $661.8 and $667.4 per surgery, without considering the cost of the intraocular lens (IOL). CONCLUSION A profitability of femtosecond laser systems for cataract surgery can be obtained after a detailed financial analysis, especially in those centers with large volumes of patients. The cost of the surgery for patients should be adapted to the real flow of patients with the ability of paying a reasonable range of cost. PMID:27500115

  12. Inhibition of Escherichia coli respiratory enzymes by short visible femtosecond laser irradiation

    International Nuclear Information System (INIS)

    A visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner. However, the mechanism of how a visible femtosecond laser affects the viability of different microorganisms is still elusive. In this paper, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E. coli) irradiated by a visible femtosecond laser (λ = 415 nm, pulse width = 100 fs) with different exposure times were investigated. Our results showed that femtosecond laser treatment for 60 min led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of the E. coli cell membrane. In comparison, a 10 min exposure of bacteria to femtosecond laser irradiation induced an immediate reduction of 75% in the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected. Results from enzymatic assays showed that oxidases and dehydrogenases involved in the E. coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to have a dominant effect on the early stage of bacteria inactivation. (paper)

  13. Laser ablation of iron: A comparison between femtosecond and picosecond laser pulses

    International Nuclear Information System (INIS)

    In this study, a comparison between femtosecond (fs) and picosecond (ps) laser ablation of electrolytic iron was carried out in ambient air. Experiments were conducted using a Ti:sapphire laser that emits radiation at 785 nm and at pulse widths of 110 ps and 130 fs, before and after pulse compression, respectively. Ablation rates were calculated from the depth of craters produced by multiple laser pulses incident normally to the target surface. Optical and scanning electron microscopy showed that picosecond laser pulses create craters that are deeper than those created by the same number of femtosecond laser pulses at the same fluence. Most of the ablated material was ejected from the ablation site in the form of large particles (few microns in size) in the case of picosecond laser ablation, while small particles (few hundred nanometers) were produced in femtosecond laser ablation. Thermal effects were apparent at high fluence in both femtosecond and picosecond laser ablation, but were less prevalent at low fluence, closer to the ablation threshold of the material. The quality of craters produced by femtosecond laser ablation at low fluence is better than those created at high fluence or using picosecond laser pulses

  14. Adiabatic femtosecond pulse compression and control by using quadratic cascading nonlinearity

    Science.gov (United States)

    Zeng, Xianglong; Ashihara, Satoshi; Shimura, Tsutomu; Kuroda, Kazuo

    2008-01-01

    We experimentally demonstrate that adiabatic compression of femtosecond pulse can be achieved by employing the management of quadratic cascading nonlinearity in quasi-phase-matching gratings. Cascading nonlinearity is not a simple analogy with third-order optical nonlinearity in term of the engineering properties of the magnitude and focusing (or defocusing) nonlinearity. Femtosecond pulse compression is investigated based on type-I (e: o + o) collinear QPM geometry of aperiodically poled MgO-doped LiNbO 3 (MgO: LN). Group-velocity-matching condition is chosen to generate quadratic femtosecond soliton consisting of fundamental (FF) and second harmonic (SH) pulses. Adiabatic-like compression process is observed in the length of 50 mm linearly chirped QPM. Cascading nonlinearity is local managed, instead of dispersion management used in fiber adiabatic soliton compression. Quadratic soliton including FF and SH pulses are obtained from the compression of 95 fs FF pulse in the initial experiments. Dependence on the phase mismatch and group velocity mismatch, cascading nonlinearity has a flexible property and presents a new challenge for exploring femtosecond pulse shaping and control. The demonstrated pulse compression and control based on cascading nonlinearity is useful for generation of shorter pulses with clean temporal profiles, efficient femtosecond second harmonic generation and group-velocity control.

  15. Fabrication of high quality optical coherence tomography (OCT) calibration artefacts using femtosecond inscription

    Science.gov (United States)

    Lee, Graham C. B.; Rasakanthan, Janarthanan; Woolliams, Peter D.; Sugden, Kate

    2012-06-01

    Optical coherence tomography (OCT) is a non-invasive three-dimensional imaging system that is capable of producing high resolution in-vivo images. OCT is approved for use in clinical trials in Japan, USA and Europe. For OCT to be used effectively in a clinical diagnosis, a method of standardisation is required to assess the performance across different systems. This standardisation can be implemented using highly accurate and reproducible artefacts for calibration at both installation and throughout the lifetime of a system. Femtosecond lasers can write highly reproducible and highly localised micro-structured calibration artefacts within a transparent media. We report on the fabrication of high quality OCT calibration artefacts in fused silica using a femtosecond laser. The calibration artefacts were written in fused silica due to its high purity and ability to withstand high energy femtosecond pulses. An Amplitude Systemes s-Pulse Yb:YAG femtosecond laser with an operating wavelength of 1026 nm was used to inscribe three dimensional patterns within the highly optically transmissive substrate. Four unique artefacts have been designed to measure a wide variety of parameters, including the points spread function (PSF), modulation transfer function (MTF), sensitivity, distortion and resolution - key parameters which define the performance of the OCT. The calibration artefacts have been characterised using an optical microscope and tested on a swept source OCT. The results demonstrate that the femtosecond laser inscribed artefacts have the potential of quantitatively and qualitatively validating the performance of any OCT system.

  16. M\\'{e}canismes fondamentaux de l'ablation laser femtoseconde en "flux interm\\'{e}diaire"

    OpenAIRE

    Petite, Guillaume

    2005-01-01

    This chapter aims at identifying what is specific to femtosecond laser ablation. It reviews the essential basic processes which contribute to femtosecond laser ablation of various materials : energy absorption by the material's electrons, electronic relaxation processes involving either electron-electron or electron-lattice interactions. A number of widely used models are briefly discussed, as well as some pending questions.

  17. Femtosecond dynamics of electronic populations in silver nano-particles

    International Nuclear Information System (INIS)

    This work deals with the dynamic of relaxation of hot electrons in silver nano-particles in a transparency matrix. Using laser impulses of a few hundred femtosecond, out equilibrium electronic populations are created and their relaxation is studied by the energy transfer to the crystalline network. The size and the geometry of these nano-particles lead to great optical non-linearities and electric confinement effects. This confinement leads then to a collective mode, named surface plasmon. Thanks to its structure, the silver owns a surface plasmon resonance far from the interband transitions, which allows the study of this collective mode. Differential measures, in degenerated pump-probe configuration and on silver nano-particles, show a slowing of the dynamic at the surface plasmon resonance. In a non degenerated pump-probe configuration, the differential transmission spectra show an asymmetrical first derivative behavior of the absorption ray. The author shows also that the relaxation dynamics depends of the nano-particles size and of the host matrix. (A.L.B.)

  18. Robust Non-Wetting PTFE Surfaces by Femtosecond Laser Machining

    Directory of Open Access Journals (Sweden)

    Fang Liang

    2014-08-01

    Full Text Available Nature shows many examples of surfaces with extraordinary wettability, which can often be associated with particular air-trapping surface patterns. Here, robust non-wetting surfaces have been created by femtosecond laser ablation of polytetrafluoroethylene (PTFE. The laser-created surface structure resembles a forest of entangled fibers, which support structural superhydrophobicity even when the surface chemistry is changed by gold coating. SEM analysis showed that the degree of entanglement of hairs and the depth of the forest pattern correlates positively with accumulated laser fluence and can thus be influenced by altering various laser process parameters. The resulting fibrous surfaces exhibit a tremendous decrease in wettability compared to smooth PTFE surfaces; droplets impacting the virgin or gold coated PTFE forest do not wet the surface but bounce off. Exploratory bioadhesion experiments showed that the surfaces are truly air-trapping and do not support cell adhesion. Therewith, the created surfaces successfully mimic biological surfaces such as insect wings with robust anti-wetting behavior and potential for antiadhesive applications. In addition, the fabrication can be carried out in one process step, and our results clearly show the insensitivity of the resulting non-wetting behavior to variations in the process parameters, both of which make it a strong candidate for industrial applications.

  19. Femtosecond-laser processing of nitrobiphenylthiol self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Schröter, Anja; Franzka, Steffen [Fakultät für Chemie, Universität Duisburg-Essen, 45117 Essen (Germany); CENIDE – Center for Nanointegration Duisburg-Essen, 47048 Duisburg (Germany); Koch, Jürgen; Chichkov, Boris N. [LZH – Laser Zentrum Hannover e. V., Hollerithallee 8, 30419 Hannover (Germany); Ostendorf, Andreas [Fakultät für Maschinenbau, Ruhruniversität Bochum, Universitätsstr. 150, 44801 Bochum (Germany); Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Fakultät für Chemie, Universität Duisburg-Essen, 45117 Essen (Germany); CENIDE – Center for Nanointegration Duisburg-Essen, 47048 Duisburg (Germany)

    2013-08-01

    Single-pulse femtosecond laser patterning of nitrobiphenylthiol monolayers on Au-coated Si substrates at λ = 800 nm, τ < 30 fs and ambient conditions has been investigated. After laser processing wet etching experiments are performed. Laser irradiation reduces the chemical resistance of the coating. In particular, the monolayer acts as a positive-tone resist. Burr-free pattern transfer is feasible at laser pulse fluences between 1 and 2.7 J/cm{sup 2}. Minimum structure sizes at a 1/e laser spot diameter of about 1 μm are close to 300 nm, i.e. sub-wavelength processing is demonstrated. Noteworthy, however, no indications for negative-tone resist properties of processed monolayers are evident, that is, cross-linking of the biphenyl moieties, if at all, is marginal. Also, complementary labeling experiments provide no evidence for chemical transformation of the nitro end groups into amine functionalities. Perspectives of resonant fs-laser processing in exploiting the particular prospects of nitrobiphenylthiol monolayers as negative-tone resists and chemically patternable platforms are discussed.

  20. Formation of Si structure in glass with a femtosecond laser

    Science.gov (United States)

    Miura, Kiyotaka; Hirao, Kazuyuki; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Kanehira, Shingo

    2008-10-01

    Mixing metallic Al into the starting material for silicate glass is proposed as a means of forming Si structures in glass. We confirmed that Si nanocrystals are space-selectively deposited in silicate glass via a thermite reaction triggered by femtosecond laser pulses. Small Si particles were transformed into larger, but still micrometer sized, Si particles by laser irradiation. These structures grew to micro-size particles due to the thermite reaction promoted by heat treatment. We discuss what effect the irradiation of the focused laser pulse had on the Si deposition process in the laser-irradiated region. Localized high temperatures and pressures and generation of shock waves appear to be very important in forming Si-rich structures that contribute to the growth of Si particles. The diffusion of calcium ions by the generation of shock waves and the presence of Al-rich structures is important for forming Si-rich structures such as Si clusters, which is achieved by continuously breaking Si-O bonds using localized high temperatures.

  1. Postoperative Endophthalmitis Caused by Staphylococcus haemolyticus following Femtosecond Cataract Surgery.

    Science.gov (United States)

    Wong, Margaret; Baumrind, Benjamin R; Frank, James H; Halpern, Robert L

    2015-01-01

    A 53-year-old Caucasian man underwent femtosecond cataract surgery and then presented with pain and hand motions vision 1 day following surgery. Anterior segment examination showed a 2-mm-layered hypopyon, a well-centered intraocular lens in the sulcus, and an obscured view to the fundus. B-scan ultrasonography showed significant vitritis and that the retina was attached. A tap and an injection of vancomycin 1 mg per 0.1 ml and of ceftazidime 2.25 mg per 0.1 ml were performed. The tap eventually yielded culture results positive for Staphylococcus haemolyticus, which was sensitive to vancomycin. We report a case of endophthalmitis that occurred on postoperative day 1 following complicated cataract surgery. This is an uncommon bacterium that is not widely reported in the literature as a cause of endophthalmitis in the postoperative period. We urge clinicians to consider S. haemolyticus as an offending agent, especially when the infection presents very early and aggressively in the postoperative period. PMID:26951642

  2. Femtosecond laser capsulotomy versus manual capsulotomy: a Meta-analysis

    Science.gov (United States)

    Qian, Dao-Wei; Guo, Hai-Ke; Jin, Shang-Li; Zhang, Hong-Yang; Li, Yuan-Cun

    2016-01-01

    AIM To perform a Meta-analysis on the precision and safety of femtosecond laser (FSL) capsulotomy compared with manual continuous curvilinear capsulotomy (CCC). METHODS We searched PubMed, EMBASE, Web of Science, the Cochrane Library databases, and Clinical Trials.gov that maintained our inclusion criteria. Reference lists of retrieved articles were also reviewed. The effects of morphology of capsulorhexis and the tears of anterior capsule were calculated by using random-effect models. RESULTS We identified 4 randomized and 7 nonrandomized studies involving 2941 eyes. The diameter of capsulotomy and the rates of anterior capsule tear showed no statistically difference between FSL group and manual group (MD=0.03; 95%CI, -0.03 to 0.09, P=0.31), and (OR=1.40; 95%CI, 0.28 to 6.97, P=0.68) respectively. In terms of the circularity of capsulotomy, FSL group had a more significant advantage than the manual CCC group (MD=0.09; 95%CI, 0.05 to 0.12, P<0.0001). CONCLUSION Our Meta-analysis shows that FSL can perform a capsulotomy with more precision and higher reliability than manual CCC. The results in diameter of capsulotomy and the rate of anterior capsule tears was no significant difference between FSL and manual CCC groups. However in terms of circularity, the FSL was superior to the manual procedure. PMID:27158620

  3. Serial femtosecond crystallography of soluble proteins in lipidic cubic phase

    Directory of Open Access Journals (Sweden)

    Raimund Fromme

    2015-09-01

    Full Text Available Serial femtosecond crystallography (SFX at X-ray free-electron lasers (XFELs enables high-resolution protein structure determination using micrometre-sized crystals at room temperature with minimal effects from radiation damage. SFX requires a steady supply of microcrystals intersecting the XFEL beam at random orientations. An LCP–SFX method has recently been introduced in which microcrystals of membrane proteins are grown and delivered for SFX data collection inside a gel-like membrane-mimetic matrix, known as lipidic cubic phase (LCP, using a special LCP microextrusion injector. Here, it is demonstrated that LCP can also be used as a suitable carrier medium for microcrystals of soluble proteins, enabling a dramatic reduction in the amount of crystallized protein required for data collection compared with crystals delivered by liquid injectors. High-quality LCP–SFX data sets were collected for two soluble proteins, lysozyme and phycocyanin, using less than 0.1 mg of each protein.

  4. Serial femtosecond crystallography of soluble proteins in lipidic cubic phase.

    Science.gov (United States)

    Fromme, Raimund; Ishchenko, Andrii; Metz, Markus; Chowdhury, Shatabdi Roy; Basu, Shibom; Boutet, Sébastien; Fromme, Petra; White, Thomas A; Barty, Anton; Spence, John C H; Weierstall, Uwe; Liu, Wei; Cherezov, Vadim

    2015-09-01

    Serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs) enables high-resolution protein structure determination using micrometre-sized crystals at room temperature with minimal effects from radiation damage. SFX requires a steady supply of microcrystals intersecting the XFEL beam at random orientations. An LCP-SFX method has recently been introduced in which microcrystals of membrane proteins are grown and delivered for SFX data collection inside a gel-like membrane-mimetic matrix, known as lipidic cubic phase (LCP), using a special LCP microextrusion injector. Here, it is demonstrated that LCP can also be used as a suitable carrier medium for microcrystals of soluble proteins, enabling a dramatic reduction in the amount of crystallized protein required for data collection compared with crystals delivered by liquid injectors. High-quality LCP-SFX data sets were collected for two soluble proteins, lysozyme and phycocyanin, using less than 0.1 mg of each protein. PMID:26306196

  5. Serial femtosecond crystallography of soluble proteins in lipidic cubic phase

    Energy Technology Data Exchange (ETDEWEB)

    Fromme, Raimund; Ishchenko, Andrii; Metz, Markus; Chowdhury, Shatabdi Roy; Basu, Shibom; Boutet, Sébastien; Fromme, Petra; White, Thomas A.; Barty, Anton; Spence, John C. H.; Weierstall, Uwe; Liu, Wei; Cherezov, Vadim

    2015-08-04

    Serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs) enables high-resolution protein structure determination using micrometre-sized crystals at room temperature with minimal effects from radiation damage. SFX requires a steady supply of microcrystals intersecting the XFEL beam at random orientations. An LCP–SFX method has recently been introduced in which microcrystals of membrane proteins are grown and delivered for SFX data collection inside a gel-like membrane-mimetic matrix, known as lipidic cubic phase (LCP), using a special LCP microextrusion injector. Here, it is demonstrated that LCP can also be used as a suitable carrier medium for microcrystals of soluble proteins, enabling a dramatic reduction in the amount of crystallized protein required for data collection compared with crystals delivered by liquid injectors. High-quality LCP–SFX data sets were collected for two soluble proteins, lysozyme and phycocyanin, using less than 0.1 mg of each protein.

  6. Comparison Of Photorefractive Keratectomy Versus Femtosecond Lasik For Correction Myopia

    Directory of Open Access Journals (Sweden)

    Salem Ali Alsalem

    2013-10-01

    Full Text Available This study aimed to compare and determine the differences in visual acuity, complications and higher order aberration (HOAs in eyes with stable myopia undergoing either photorefractive keratectomy (PRK or femtosecond Lasik (Fs Lasik flaps were created with an intended thickness of 100 µm, diameter of 8.4 to 9.0 mm, superior hinge, at one month postoperatively. Prospective study, randomized pilot study, refractive surgery was performed on 40 eyes: 20 eyes with PRK and 20 eyes with Fs Lasik. Primary outcomes measures were uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA and complications. Higher order aberration was as a secondary measurement. At one month postoperative in Fs Lasik eyes more improvement UDVA, CDVA was statically different between group at 1 month 25% of PRK group losing a line or more from preoperative while 10%of Fs group lost only 1 line .35% of Fs group gained a line by a month compared of 10%of PRK group .Types of complications different between groups: eight eyes in Fs Lasik group experiencing complications including diffuse lamellar keratitis (DLK with no loss of UDVA or CDVA. There were slightly significant differences between groups in any HOAs, spherical and coma aberrations were increased compared with preoperative conditions. At 1-month follow-up, Fs Lasik group demonstrated clinically and statistically significant better visual acuity and higher order aberrations HOA than the PRK group with differences in experienced complications.

  7. Femtosecond laser processing with a holographic line-shaped beam.

    Science.gov (United States)

    Hasegawa, Satoshi; Shiono, Koji; Hayasaki, Yoshio

    2015-09-01

    Line-shaped femtosecond pulses are well-suited to large-area machining with high throughput in laser cutting, peeling, and grooving of materials. First, we demonstrated the single-shot fabrication of a line structure in a glass surface using a line-shaped pulse generated by a holographic cylindrical lens displayed on a liquid-crystal spatial light modulator. We found the line structure was uniform and smooth near the ends because of the ability to precisely control the intensity distribution and to achieve single-shot fabrication. Second, we demonstrated a line-shaped beam deformed three-dimensionally for showing the potential of holographic line-shaped beam processing. Third, we demonstrated laser peeling of an indium tin oxide film. We found that little debris around the fabricated area was observed, because the debris was removed by the beam itself. Last, we demonstrated laser grooving of stainless steel. We found the swelling of the surface included upwardly growing nanogratings, although many line-shaped pulse irradiations were given. The swelling was caused by the depositions of the debris on the top of the nanogratings. PMID:26368421

  8. Femtosecond stimulated Raman spectroscopy of ultrafast biophysical reaction dynamics

    Science.gov (United States)

    McCamant, David William

    2004-12-01

    I have developed the technique of femtosecond stimulated Raman spectroscopy (FSRS), which enables the rapid acquisition of vibrational spectra with optical excitation to S2 (1Bu +) the molecule relaxes to S1 in 160 fs where it undergoes rapid two-step IVR with 200- and 450-fs time constants. In later work, the FSRS spectrum of S2 beta-carotene was observed, which consists of three intense and broad bands at ˜1100, 1300 and 1650 cm-1 that exhibit kinetics matching the decay of the S2 near-infrared absorption. These data show that there is no additional intermediate 1B u- electronic state involved in the relaxation pathway of beta-carotene. FSRS was also used to study the photoisomerization dynamics in bacteriorhodopsin (bR). Spectra obtained during bR's excited state lifetime exhibit dispersive lineshapes at the ground-state frequencies that decay in 250 fs and are attributed to a nonlinear emission process. This relaxation is significantly faster than the decay of the stimulated emission (˜500 fs), indicating that the excited population moves away from the ground-state geometry in 250 fs. Spectral changes between 1.5 to 100 ps reveal that a significant fraction of the isomerization occurs on the ground state photoproduct surface. The many benefits FSRS will make it a valuable tool for vibrational spectroscopy of reaction dynamics in ultrafast photochemical and photophysical processes.

  9. Refining femtosecond laser induced periodical surface structures with liquid assist

    International Nuclear Information System (INIS)

    Highlights: ► LIPSS on silicon wafer was made in air and in ethanol environment. ► Ethanol environment produce cleaner surface ripples. ► Ethanol environment decrease spatial wavelength of the LIPSS by 30%. ► More number of pulses produce smaller spatial wavelength in air. ► Number of pulses do not influence spatial wavelength in ethanol environment. - Abstract: Laser induced periodic surface structures were generated on silicon wafer using femtosecond laser. The medium used in this study is both air and ethanol. The laser process parameters such as wavelength, number of pulse, laser fluence were kept constant for both the mediums. The focus of the study is to analyze spatial wavelength. When generating surface structures with air as a medium and same process parameter of the laser, spatial wavelength results showed a 30% increase compared to ethanol. The cleanliness of the surface generated using ethanol showed considerably less debris than in air. The results observed from the above investigation showed that the medium plays a predominant role in the generation of surface structures.

  10. Femtosecond laser ablation of brass in air and liquid media

    International Nuclear Information System (INIS)

    Laser ablation of brass in air, water, and ethanol was investigated using a femtosecond laser system operating at a wavelength of 785 nm and a pulse width less than 130 fs. Scanning electron and optical microscopy were used to study the efficiency and quality of laser ablation in the three ablation media at two different ablation modes. With a liquid layer thickness of 3 mm above the target, ablation rate was found to be higher in water and ethanol than in air. Ablation under water and ethanol showed cleaner surfaces and less debris re-deposition compared to ablation in air. In addition to spherical particles that are normally formed from re-solidified molten material, micro-scale particles with varying morphologies were observed scattered in the ablated structures (craters and grooves) when ablation was conducted under water. The presence of such particles indicates the presence of a non-thermal ablation mechanism that becomes more apparent when ablation is conducted under water.

  11. Femtosecond photoelectron and photoion spectrometer with vacuum ultraviolet probe pulses

    CERN Document Server

    Koch, Markus; Grilj, Jakob; Sistrunk, Emily; Gühr, Markus

    2014-01-01

    We describe a setup to study ultrafast dynamics in gas-phase molecules using time-resolved photoelectron and photoion spectroscopy. The vacuum ultraviolet (VUV) probe pulses are generated via strong field high-order harmonic generation from infrared femtosecond laser pulses. The band pass characteristic in transmission of thin indium (In) metal foil is exploited to isolate the $9^{\\text{th}}$ harmonic of the 800 nm fundamental (H9, 14 eV, 89 nm) from all other high harmonics. The $9^{\\text{th}}$ harmonic is obtained with high conversion efficiencies and has sufficient photon energy to access the complete set of valence electron levels in most molecules. The setup also allows for direct comparison of VUV single-photon probe with 800 nm multi-photon probe without influencing the delay of excitation and probe pulse or the beam geometry. We use a magnetic bottle spectrometer with high collection efficiency for electrons, serving at the same time as a time of flight spectrometer for ions. Characterization measurem...

  12. Using femtosecond lasers to modify sizes of gold nanoparticles

    Science.gov (United States)

    da Silva Cordeiro, Thiago; Almeida de Matos, Ricardo; Silva, Flávia Rodrigues de Oliveira; Vieira, Nilson D.; Courrol, Lilia C.; Samad, Ricardo E.

    2016-04-01

    Metallic nanoparticles are important on several scientific, medical and industrial areas. The control of nanoparticles characteristics has fundamental importance to increase the efficiency on the processes and applications in which they are employed. The metallic nanoparticles present specific surface plasmon resonances (SPR). These resonances are related with the collective oscillations of the electrons presents on the metallic nanoparticle. The SPR is determined by the potential defined by the nanoparticle size and geometry. There are several methods of producing gold nanoparticles, including the use of toxic chemical polymers. We already reported the use of natural polymers, as for example, the agar-agar, to produce metallic nanoparticles under xenon lamp irradiation. This technique is characterized as a "green" synthesis because the natural polymers are inoffensive to the environment. We report a technique to produce metallic nanoparticles and change its geometrical and dimensional characteristics using a femtosecond laser. The 1 ml initial solution was irradiate using a laser beam with 380 mW, 1 kHz and 40 nm of bandwidth centered at 800 nm. The setup uses an Acousto-optic modulator, Dazzler, to change the pulses spectral profiles by introduction of several orders of phase, resulting in different temporal energy distributions. The use of Dazzler has the objective of change the gold nanoparticles average size by the changing of temporal energy distributions of the laser pulses incident in the sample. After the laser irradiation, the gold nanoparticles average diameter were less than 15 nm.

  13. Femtosecond spectroscopic study of carminic acid-DNA interactions

    International Nuclear Information System (INIS)

    Photo-excited carminic acid and carminic acid-DNA complexes in a buffer solution at pH 7 have been examined using a variety of spectroscopy techniques, that are in particular, the femtosecond resolved fluorescence upconversion and transient absorption spectroscopy. The observation of dual fluorescence emission, one peaks at 470 nm and the other at 570 nm, indicates to an excited-state (S1) intramolecular proton transfer (ESIPT). A detailed analysis of the transient absorption measurements of an aqueous carminic-acid solution at pH 7 yielded four lifetimes for the excited-state (S1): 8, 15, 33 and 46 ps. On the other hand, only two lifetimes, 34 and 47 ps, were observed by fluorescence upconversion spectroscopy because of the detection limitation to the long wavelength edge of the carminic-acid spectrum. The four S1 lifetimes were ascribed to the coexistence of respectively two tautomer (normal and tautomer) forms of carminic acid, in the non-dissociated state (CAH) and in the deprotonated state (CA-). The fluorescence upconversion measurements of carminic acid-DNA complexes exhibited a prolongation of the fluorescence lifetimes. This effect was accepted as evidence for the formation of intercalation complexes between the carminic acid and the DNA. The intercalative binding of the carminic acid to DNA was confirmed by the fluorescence titration experiments resulting to a binding constant of 2 x 105 M-1 that is typical for anthracycline-DNA complexes

  14. Adaptable acylindrical microlenses fabricated by femtosecond laser micromachining

    Science.gov (United States)

    Paiè, Petra; Bragheri, Francesca; Claude, Theo; Osellame, Roberto

    2015-03-01

    Microfluidic lenses are a powerful tool for many lab on a chip applications ranging from sensing to detection and also to imaging purpose, with the great advantage to increase the degree of integration and compactness of these micro devices. In this work we present the realization of such a compact microfluidic lens with reconfigurable optical properties. The technique used to realize the device we present is femtosecond laser micromachining followed by chemical etching, which allows to easily fabricate 3D microfluidic devices with an arbitrary shape. Thanks to that it has been possible to easily fabricate different lens made up by cylindrical microchannel in fused silica glasses filled with liquids with a proper refractive index. The optical properties of these devices are tested and shown to be in a good agreement with the theoretical model previously implemented. Furthermore we have also optimized the design of these microlenses in order to reduce the effects of spherical aberrations in the focal region, thus allowing us to obtain a set of different acylindrical microfluidic lenses, whose validation is also reported. In this work the lens adaptability can be achieved by replacing the liquid inside the microchannel, so that we can easily tune the feature of the focused beam. Thus increasing the possible range of applications of these micro optical elements, as an example we report on the validation of the device as a fast integrated optofluidic shutter.

  15. Theoretical femtosecond physics atoms and molecules in strong laser fields

    CERN Document Server

    Grossmann, Frank

    2013-01-01

    Theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers up to atomic field strengths on the order of 10^16 W/cm² are leading to an understanding of many challenging experimental discoveries. This book deals with the basics of femtosecond physics and goes up to the latest applications of new phenomena. The book presents an introduction to laser physics with mode-locking and pulsed laser operation. The solution of the time-dependent Schrödinger equation is discussed both analytically and numerically. The basis for the non-perturbative treatment of laser-matter interaction in the book is the numerical solution of the time-dependent Schrödinger equation. The light field is treated classically, and different possible gauges are discussed. Physical phenonema, ranging from Rabi-oscillations in two-level systems to the ionization of atoms, the generation of high harmonics, the ionization and dissociation of molecules as well as the control of chemical reactions are pre...

  16. Femtosecond THz Studies of Intra-Excitonic Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Rupert; Schmid, Ben A.; Kaindl, Robert A.; Chemla, Daniel S.

    2007-10-02

    Few-cycle THz pulses are employed to resonantly access the internal fine structure of photogenerated excitons in semiconductors, on the femtosecond time scale. This technique allows us to gain novel insight into many-body effects of excitons and reveal key quantum optical processes. We discuss experiments that monitor the density-dependent re?normalization of the binding energy of a high-density exciton gas in GaAs/AlGaAs quantum wells close to the Mott transition. In a dilute ensemble of 3p excitons in Cu2O, stimulated THz emission from internal transitions to the energetically lower 2s state is observed at a photon energy of 6.6 meV, with a cross section of 10-14 cm2. Simultaneous interband excitation of both exciton levels drives quantum beats, which cause efficient THz emission at the difference frequency. By extending this principle to various other exciton resonances, we develop a novel way of mapping the fine structure by two-dimensional THz emission spectroscopy.

  17. Femtosecond laser-induced breakdown spectroscopy of sea water

    International Nuclear Information System (INIS)

    The composition of the line and band spectra of the plasma induced by a femtosecond laser pulse on the surface of sea water is determined. The temporal behaviors of the intensity of the continuum and the Ca II, Mg II and Na I lines are investigated. It is shown that the time dependence of the intensity of the Na I line is described by a monoexponential function. The characteristic decay times of the line intensities of Mg II and Na I were used to estimate the three-body recombination times. Using these values, we estimate the electron number density and the feasibility of Local Thermodynamic Equilibrium (LTE) criterion. A method involving excitation rate constants is proposed for the comparison of detection limits. For a plasma generated on a liquid surface, the following relation among detection limits will be obtained: LOD(Na) 2 were recorded. • Recombination determines characteristic decay time of line intensity. • Three-body recombination time was used to estimate electron density. • Excitation rate constants allow to determine relation of detection limits

  18. Surface ablation of transparent polymers with femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Florian, C.; Caballero-Lucas, F.; Fernández-Pradas, J.M., E-mail: jmfernandez@ub.edu; Morenza, J.L.; Serra, P.

    2014-05-01

    In this work, a study of the laser ablation on the surface of poly methyl-methacrylate (PMMA) is presented. Experiments were performed with a femtosecond laser delivering 450 fs pulses at a wavelength of 1027 nm. The laser beam energy was controlled through a polarizer based attenuator and measured by a calibrated photodiode energy meter. A focusing method called z-scan is used to place the sample on the beam waist. This method uses a second energy meter placed behind the sample, which was used to monitor the energy transmitted across the sample in situ. Thus, the absorption was evaluated by comparing the measurements of both energy meters. The z-scan method is evaluated by studying the laser ablation in three different positions between the sample and the laser beam waist. It is found that above a threshold energy that depends on the focusing conditions, the absorbance of the samples increases with the pulse energy. After irradiation, dimensional analysis of the craters produced at different pulse energies is performed in order to determine the best focusing conditions and the ablation threshold for ablation of PMMA samples.

  19. Elaboration of submicron structures on PEEK polymer by femtosecond laser

    International Nuclear Information System (INIS)

    Highlights: • We compare PEEK polymer under two crystalline forms: semi-crystalline and amorphous. • We assess topographical modifications of surface morphologies after femtosecond laser irradiation. • At low laser energy regime, there is an influence of the crystallinity rate on topographical features of surface morphologies. • At high laser energy regime, the contribution of the crystallinity tends to disappear. - Abstract: In this work, laser parameters initiating the emergence of periodic structures, so-called ripples on poly (ether ether ketone) (PEEK) surfaces, are investigated. PEEK was used in its semi-crystalline and amorphous forms. Polymer surfaces were treated locally by performing a matrix of laser impacts to highlight the influence of the crystallinity in ultrashort laser interaction. Different surface morphologies or ripples were analyzed by atomic force microscopy and optical interferometry. A map of the presence of these different morphologies according to the laser fluence and the number of pulses was established. Analysis by optical interferometry was carried out and led to the calculations of ablation efficiency. Some significant differences were demonstrated between amorphous and semi-crystalline surfaces. This work revealed topographical information on the local behavior of the irradiated material. Finally, the crystallinity rate of polymer surface seems to be a determinant factor for the periodic nanostructured appearance

  20. Elaboration of submicron structures on PEEK polymer by femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Hammouti, S., E-mail: sabrina.hammouti@ec-lyon.fr [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Beaugiraud, B.; Salvia, M. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Mauclair, C. [LaHC, Université Jean Monnet, 18 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Pascale-Hamri, A. [MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Benayoun, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Valette, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France)

    2015-02-01

    Highlights: • We compare PEEK polymer under two crystalline forms: semi-crystalline and amorphous. • We assess topographical modifications of surface morphologies after femtosecond laser irradiation. • At low laser energy regime, there is an influence of the crystallinity rate on topographical features of surface morphologies. • At high laser energy regime, the contribution of the crystallinity tends to disappear. - Abstract: In this work, laser parameters initiating the emergence of periodic structures, so-called ripples on poly (ether ether ketone) (PEEK) surfaces, are investigated. PEEK was used in its semi-crystalline and amorphous forms. Polymer surfaces were treated locally by performing a matrix of laser impacts to highlight the influence of the crystallinity in ultrashort laser interaction. Different surface morphologies or ripples were analyzed by atomic force microscopy and optical interferometry. A map of the presence of these different morphologies according to the laser fluence and the number of pulses was established. Analysis by optical interferometry was carried out and led to the calculations of ablation efficiency. Some significant differences were demonstrated between amorphous and semi-crystalline surfaces. This work revealed topographical information on the local behavior of the irradiated material. Finally, the crystallinity rate of polymer surface seems to be a determinant factor for the periodic nanostructured appearance.