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1

Renard, William, Clément Chan, Antoine Dubrouil, Jérôme Lhermite, Giorgio Santarelli, and Romain Royon. "Agile femtosecond synchronizable laser source from a gated CW laser." Laser Physics Letters 19, no. 7 (2022): 075105. http://dx.doi.org/10.1088/1612-202x/ac7133.

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Abstract In this letter we demonstrate agile femtosecond pulse generation with a widely tunable repetition rate (10–100 MHz) from a continuous wave laser diode optically gated by a Mach–Zehnder electro-optic intensity modulator. Initial sub-50 ps pulses are strongly spectral broadened (>5 nm) by self-phase modulation in a polarization maintaining single-mode fiber. A tunable optical pulse train with pulse durations of a few hundred femtoseconds is obtained using a simple fixed grating compressor, thanks to spectral broadening saturation phenomena. The source is easily synchronized with low
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2

Ye, Hanyu, Florian Leroy, Lilia Pontagnier, Giorgio Santarelli, Johan Boullet, and Eric Cormier. "Non-linear amplification to 200 W of an electro-optic frequency comb with GHz tunable repetition rates." EPJ Web of Conferences 287 (2023): 07025. http://dx.doi.org/10.1051/epjconf/202328707025.

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We present a monolithic Yb-doped fiber laser system delivering 200 W average power of femtosecond pulses at tunable GHz repetition rates. The system is based on a GHz electro-optic (EO) frequency comb operating in the nonlinear regime. The EO comb pulses at 1 µm wavelength are initially pre-compressed to sub-2 ps, amplified to 2.5 W, and finally boosted to 200 W in a newly designed large-mode-area, Yb-doped photonic crystal fiber. Continuously tunable across 1-18 GHz, the picosecond pulses experience nonlinear propagation in the booster amplifier, leading to output pulses compressible down to
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3

Zeng, Li, Xiaofan Wang, Yifan Liang, Huaiqian Yi, Weiqing Zhang, and Xueming Yang. "Chirped-Pulse Amplification in an Echo-Enabled Harmonic-Generation Free-Electron Laser." Applied Sciences 13, no. 18 (2023): 10292. http://dx.doi.org/10.3390/app131810292.

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The field of ultrafast science has experienced significant growth over the last decade, largely attributed to advancements in optical and laser technologies such as chirped-pulse amplification and high-harmonic generation. The distinctive characteristics of intense ultrafast free-electron lasers (FELs) have introduced novel prospects for investigating molecular dynamics, as well as providing an opportunity to gain deeper insights into nonlinear processes in materials. Therefore, high-power ultrafast FELs can be widely used for both fundamental research and practical applications. This study pr
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4

Saha, Asit. "Bifurcation analysis of the propagation of femtosecond pulses for the Triki-Biswas equation in monomode optical fibers." International Journal of Modern Physics B 33, no. 29 (2019): 1950346. http://dx.doi.org/10.1142/s0217979219503466.

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Bifurcation analysis of the propagation of femtosecond pulses for the Triki–Biswas (TB) equation in monomode optical fibers is reported for the first time. Bifurcation of phase plots of the dynamical system is dispensed using phase plane analysis through symbolic computation. It is observed that the TB equation supports femtosecond solitary pulse, periodic pulse, superperiodic pulse, kink and anti-kink pulses, which are presented through time series plot numerically. Analytical forms of the femtosecond solitary pulses are obtained. This contribution may be applicable to interpret the dynamical
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5

Zhu, Chang Jun, Jun Fang He, Xue Jun Zhai, Bing Xue, and Chong Hui Zhang. "Two Synchronized Operating Modes of Femtosecond and Picosecond Pulses in a Dual-Wavelength Laser." Materials Science Forum 663-665 (November 2010): 284–87. http://dx.doi.org/10.4028/www.scientific.net/msf.663-665.284.

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Two synchronized operating modes of femtosecond and picosecond pulses, cross mode-locking and multi-pulse operating, are presented in a two-beam-pumped dual-wavelength Ti:sapphire laser. For the cross mode-locking mode, synchronized laser pulses of 37.5 fs and 0.891ps, with a timing jitter of 139 fs, are obtained in the femtosecond cavity and picosecond cavity, respectively. For the multi-pulse mode, pulses of 35 fs are obtained in the femtosecond cavity, whereas, multi-pulse mode appears in the picosecond cavity, with a pulse envelope width of 1.06 ps. The two operating modes can be switched
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6

Rudenkov, A. S., V. E. Kisel, A. S. Yasukevich, K. L. Hovhannesyan, A. G. Petrosyan, and N. V. Kuleshov. "Yb:CALYO-based femtosecond chirped pulse regenerative amplifier for temporally resolved pump-probe spectroscopy." Devices and Methods of Measurements 9, no. 3 (2018): 205–14. http://dx.doi.org/10.21122/2220-9506-2018-9-3-205-214.

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Diode-pumped femtosecond chirped pulse regenerative amplifiers based on Yb3+-materials are of practical importance for wide range of scientific, industrial and biomedical applications. The aim of this work was to study the amplification of broadband chirped femtosecond pulses in regenerative amplifier based on Yb3+:CaYAlO4crystal.Such systems use femtosecond mode-locked lasers as seed pulse sources and amplify nJ-seed pulses to sub-mJ energy range. Most chirped pulse regenerative amplifier systems described in the literature use seed lasers with typical pulse spectral width at the level of 10–
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7

Jana, Kamalesh, Amit D. Lad, Ankit Dulat, Yash M. Ved, and G. Ravindra Kumar. "Ultrafast time-resolved two-dimensional velocity mapping of the hot-dense plasmas generated by intense-laser pulses." AIP Advances 12, no. 9 (2022): 095112. http://dx.doi.org/10.1063/5.0102048.

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Experimental measurements of spatially resolved ultrafast dynamics of the critical surface in ultra-intense laser–solid interactions are essential for a proper understanding of the physical mechanism of the interaction. Resolving ultrafast motion at both the relevant length scales (micrometers) and timescales (femtoseconds) simultaneously has been a challenging task. Here, we demonstrate a novel technique for mapping the spatiotemporal dynamics of hot and solid dense plasma created by high contrast (picosecond contrast ∼10−9) femtosecond relativistic intensity laser pulses. This pump–probe Dop
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8

Spence, Stephanie, Takaaki Harada, Athanasios Margiolakis, et al. "Applicability of Femtosecond Lasers in the Cross-section Sampling of Works of Art." MRS Advances 2, no. 33-34 (2017): 1801–4. http://dx.doi.org/10.1557/adv.2017.242.

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ABSTRACTIssues in traditional cross-section sampling of paintings and other cultural artifacts with a scalpel, such as crumbling, delamination and paint compression, can deter conservators from sampling fragile paint layers. Often, such sampling carries the risk of causing further damage from a scalpel, which outweighs the benefits of scientific investigation. Here, we show that femtosecond lasers offer a viable alternative to obtaining cross-sections with minimal damage to the surrounding artwork. A Regenerative Ti:Sapphire amplifier system with a pulse duration of 70 femtoseconds, a few mill
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9

Neutze, Richard. "Opportunities and challenges for time-resolved studies of protein structural dynamics at X-ray free-electron lasers." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1647 (2014): 20130318. http://dx.doi.org/10.1098/rstb.2013.0318.

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X-ray free-electron lasers (XFELs) are revolutionary X-ray sources. Their time structure, providing X-ray pulses of a few tens of femtoseconds in duration; and their extreme peak brilliance, delivering approximately 10 12 X-ray photons per pulse and facilitating sub-micrometre focusing, distinguish XFEL sources from synchrotron radiation. In this opinion piece, I argue that these properties of XFEL radiation will facilitate new discoveries in life science. I reason that time-resolved serial femtosecond crystallography and time-resolved wide angle X-ray scattering are promising areas of scienti
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10

Zhu, Jianqiang, Xinglong Xie, Meizhi Sun, Qunyu Bi, and Jun Kang. "A Novel Femtosecond Laser System for Attosecond Pulse Generation." Advances in Optical Technologies 2012 (January 15, 2012): 1–6. http://dx.doi.org/10.1155/2012/908976.

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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
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11

Dabu. "Femtosecond Laser Pulses Amplification in Crystals." Crystals 9, no. 7 (2019): 347. http://dx.doi.org/10.3390/cryst9070347.

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This paper describes techniques for high-energy laser pulse amplification in multi-PW femtosecond laser pulses. Femtosecond laser pulses can be generated and amplified in laser media with a broad emission spectral bandwidth, like Ti:sapphire crystals. By chirped pulse amplification (CPA) techniques, hundred-Joule amplified laser pulses can be obtained. Multi-PW peak-power femtosecond pulses are generated after recompression of amplified chirped laser pulses. The characteristics and problems of large bandwidth laser pulses amplification in Ti:sapphire crystals are discussed. An alternative tech
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12

Zhu, Chang Jun, Bing Xue, Xue Jun Zhai, and Jun Fang He. "Manufacture of Lasers with Multiple Operating Modes." Advanced Materials Research 482-484 (February 2012): 1937–40. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1937.

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A two-beam pumped Ti:sapphire laser with femtosecond and picosecond cavities was manufactured. Three operating modes, independent self mode-locking, cross mode-locking and multi-pulse operating, were achieved. In the independent self mode-locking mode, femtosecond and picosecond laser pulses were generated in the two cavities, respectively. In the cross mode-locking mode, synchronized femtosecond and picosecond laser pulses were obtained in the two cavities. In the multi-pulse mode, multi-pulses were produced in the picosecond cavity. The results show that, the independent self mode-locking mo
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13

Golovin, Nikolai N., and Alexander K. Dmitriev. "Pulse selector for obtaining femtosecond radiation with a controlled carrier-envelope phase." Analysis and data processing systems, no. 2 (June 28, 2022): 121–32. http://dx.doi.org/10.17212/2782-2001-2022-2-121-132.

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In non-linear optical processes, such as obtaining attosecond pulses, it is extremely important to control the carrier envelope phase. To do this, various periodic trains of identical femtosecond pulses with a controlled phase can be created. In addition, since there is no frequency comb offset in such sequences, the process of measuring optical frequencies is greatly simplified. The pulse selector has been developed to obtain a sequence of identical femtosecond pulses with a controlled carrier – envelope phase. The selector makes it possible to obtain a “pure” sequence of identical femtosecon
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14

Obata, Kotaro, Francesc Caballero-Lucas, Shota Kawabata, Godai Miyaji, and Koji Sugioka. "GHz bursts in MHz burst (BiBurst) enabling high-speed femtosecond laser ablation of silicon due to prevention of air ionization." International Journal of Extreme Manufacturing 5, no. 2 (2023): 025002. http://dx.doi.org/10.1088/2631-7990/acc0e5.

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Abstract For the practical use of femtosecond laser ablation, inputs of higher laser intensity are preferred to attain high-throughput material removal. However, the use of higher laser intensities for increasing ablation rates can have detrimental effects on ablation quality due to excess heat generation and air ionization. This paper employs ablation using BiBurst femtosecond laser pulses, which consist of multiple bursts (2 and 5 bursts) at a repetition rate of 64 MHz, each containing multiple intra-pulses (2–20 pulses) at an ultrafast repetition rate of 4.88 GHz, to overcome these conflict
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15

Wang, Huai Sheng. "The Temporal Diffraction Characteristic of a Femtosecond Laser Pulse by a Serrated Aperture." Applied Mechanics and Materials 268-270 (December 2012): 1353–56. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1353.

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Based on Fresnel diffraction theory we give out the light field distribution for the definite frequency component of a femtosecond laser pulse when the laser pulse passes through a serrated aperture. Through an inverse Fourier transformation, we get the temporal diffraction field function of the femtosecond laser pulse at any distance. The temporal diffraction field function is related to the width of the laser pulse, the structure of the serrated aperture, the Fresnel number at central frequency and time. Number calculation shows when the width of the laser pulse is within a few tens of femto
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16

Lu, Qi, Xiang Zhang, Arnaud Couairon, and Yi Liu. "Revealing Local Temporal Profile of Laser Pulses of Intensity above 1014 W/cm2." Sensors 23, no. 6 (2023): 3101. http://dx.doi.org/10.3390/s23063101.

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We demonstrated a method for in situ temporal characterization of an intense femtosecond laser pulse around its focus where the laser intensity exceeds 1014 W/cm2. Our method is based on the second harmonic generation (SHG) by a relatively weak femtosecond probe pulse and the intense femtosecond pulses under analysis in the gas plasma. With the increase in the gas pressure, it was found that the incident pulse evolves from a Gaussian profile to a more complicated structure featured by multiple peaks in the temporal domain. Numerical simulations of filamentation propagation support the experime
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17

Chen, Gao. "Isolated attosecond pulse generation from helium atom irradiated by a three-color laser pulse." Acta Physica Sinica 71, no. 5 (2022): 054204. http://dx.doi.org/10.7498/aps.71.20211502.

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Isolated attosecond pulses enables the studying and controlling of ultrafast electron processes in atoms and molecules. High-order harmonic generation (HHG) is the most promising way to generate such pulses, benefiting from the broad plateau structure of the typical HHG spectrum. We theoretically investigate high-order harmonic and attosecond pulse generation from helium atom in a three-color laser field, which is synthesized by 16 fs/1600 nm, 15 fs/1100 nm and 5 fs/800 nm pulse laser. Compared with harmonic spectrum generated by a two-color laser field synthesized by 16 fs/1600 nm and 15 fs/1
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18

Kokaj, Agon, Haxhi Kamberi, and Muhamet Kadrija. "Investigation of ablation mechanism for laser-based lithotripsy." Romanian Medical Journal 72, no. 1 (2025): 66–72. https://doi.org/10.37897/rmj.2025.1.14.

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Background. The formation of stones in organs such as the kidneys or gallbladder can lead to serious health problems, traditionally treated through conventional surgery. Laser-based techniques, particularly lithotripsy (known also as ablation), have emerged as promising alternatives due to their potential to be painless, low-cost, and suitable for outpatient procedures. Objectives. This study investigates the mechanism of destruction of kidney or gallbladder stones using femtosecond laser pulses. Specifically, it focuses on understanding how pulsed laser energy contributes to stone ablation. M
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19

Jiang, Lan, and Hai-Lung Tsai. "Energy Transport and Nanostructuring of Dielectrics by Femtosecond Laser Pulse Trains." Journal of Heat Transfer 128, no. 9 (2006): 926–33. http://dx.doi.org/10.1115/1.2241979.

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This study analyzes single burst ablation of dielectrics by a femtosecond pulse train that consists of one or multiple pulses. It is found that (1) there exist constant-ablation-depth zones with respect to fluence for one or multiple pulses per train and (2) for the same total fluence per train, although the ablation depth decreases in multiple pulses as compared to that of a single pulse, the depth of the constant-ablation-depth zone decreases. In other words, repeatable structures at the desired smaller nanoscales can be achieved in dielectrics by using the femtosecond pulse train technology
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20

SCHMIDT, M., P. D'OLIVEIRA, P. MEYNADIER, D. NORMAND, and C. CORNAGGIA. "STRONG LASER FIELD INTERACTION WITH DIATOMIC MOLECULES: FROM THE ULTRA-SHORT TO LONG-PULSE REGIME." Journal of Nonlinear Optical Physics & Materials 04, no. 04 (1995): 817–29. http://dx.doi.org/10.1142/s0218863595000367.

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In the present paper, we compare novel MEDI results on iodine obtained with 30 ps laser pulses to those obtained in the femtosecond regime. The results indicate laser-induced trapping of the molecules not only in the ultra-short pulse regime, but also for the long pulses, since the fragment kinetic energy releases are essentially the same, although the pulse duration is varied over more than two orders of magnitude. Most interestingly, with 30 ps pulses significant post-dissociation ionization of the In+-fragments observed for the first time, proving that near-Coulomb energies and post-dissoci
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21

Zhang, Aiguo, Ke Dai, Lin Huang та ін. "Tunable All-Fiber Femtosecond Electro-Optic Optical Frequency Comb Operating at 1.5 μm". Photonics 12, № 4 (2025): 311. https://doi.org/10.3390/photonics12040311.

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We propose and demonstrate a tunable femtosecond electro-optic optical frequency comb by shaping a continuous-wave seed laser in an all-fiber configuration. The seed laser, operating at 1.5 μm, is first cascade-phase-modulated and subsequently de-chirped to generate low-contrast pulses of approximately 8 ps at a repetition rate of 5.95 GHz. These pulses are then refined into clean, high-quality picosecond pulses using a Mamyshev regenerator. The generated source is further amplified using an erbium–ytterbium-doped fiber amplifier operating in a highly nonlinear regime, yielding output pulses c
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22

Aquila, A., M. Drescher, T. Laarmann, M. Barthelmeß, H. N. Chapman, and S. Bajt. "Moving the Frontier of Quantum Control into the Soft X-Ray Spectrum." International Journal of Optics 2011 (2011): 1–4. http://dx.doi.org/10.1155/2011/417075.

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The femtosecond nature of X-ray free electron laser (FEL) pulses opens up exciting research possibilities in time-resolved studies including femtosecond photoemission and diffraction. The recent developments of seeding X-ray FELs extend their capabilities by creating stable, temporally coherent, and repeatable pulses. This in turn opens the possibility of spectral engineering soft X-ray pulses to use as a probe for the control of quantum dynamics. We propose a method for extending coherent control pulse-shaping techniques to the soft X-ray spectral range by using a reflective geometry 4f pulse
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23

Sano, Tomokazu, Kengo Takahashi, Akio Hirose, and Kojiro F. Kobayashi. "Femtosecond Laser Ablation of Zr55Al10Ni5Cu30 Bulk Metallic Glass." Materials Science Forum 539-543 (March 2007): 1951–54. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1951.

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Dependence of the femtosecond laser ablation depth on the laser pulse energy was investigated for Zr55Al10Ni5Cu30 bulk metallic glass. Investigation of the femtosecond laser ablation of bulk metallic glasses has not been reported. Femtosecond laser pulses (wavelength of 800 nm, pulse width of 100 fs, pulse energies of 2 – 900 μJ) were focused and irradiated on the polished surface of metals in air. The ablation depth of the metallic glass is deeper than that of its crystallized metal at a pulse energy in the strong ablation region. We suggest that the energy loss at grain boundaries of hot ele
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24

Alshehria, A. M., El Sayed Yousefa, A. A. Alshahrania, Akram Ibrahima, Nafis Ahmada, and V. R. Bhardwajb. "Differential Nonlinear Absorption of an Elliptically Polarized Femtosecond Vortex Beam in Tellurite Glass-=SUP=-*-=/SUP=-." Журнал технической физики 128, no. 8 (2020): 1178. http://dx.doi.org/10.21883/os.2020.08.49718.293-19.

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We present differential nonlinear absorption of an elliptically polarized femtosecond laser vortex beam carrying an angular momentum of l = -1 in tellurite glass. Transmission measurements were utilized to measure the nonlinear absorption of the glass on a shot-by-shot basis, and to investigate the modification threshold for the beam. Additionally, the effect of pulse energy on the polarization ellipse was investigated. The results revealed a reduction in the ellipticity as the incident pulse energy was increased. Non-rotation of the ellipsoid indicated that there is no change in the third ord
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25

GUO, ZHONGYI, WEIQIANG DING, SHILIANG QU, JINGMIN DAI, and SHUTIAN LIU. "SELF-ASSEMBLED VOLUME GRATING IN SILICA GLASS INDUCED BY TIGHTLY FOCUSED FEMTOSECOND LASER PULSE." Journal of Nonlinear Optical Physics & Materials 18, no. 04 (2009): 625–32. http://dx.doi.org/10.1142/s0218863509004841.

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We report on self-assembled volume grating in silica glass induced by a tightly focused femtosecond laser pulse. The formation of volume grating is attributed to the multiple microexplosion in the transparent materials induced by the femtosecond pulses. The first order diffractive efficiency is greatly dependent on the energy of the pulses and the scanning velocity of the laser, and the highest reaches to nearly 30%.
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26

Bibicheva S. A., Rupasov A. E., Danilov P. A., et al. "Self-organizing half-wave gratings on the surface of silica glass." Optics and Spectroscopy 130, no. 4 (2022): 437. http://dx.doi.org/10.21883/eos.2022.04.53732.58-21.

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The interaction of femtosecond laser pulses with the surface of silica glass has been studied. As a result of interference between the incident radiation and surface plasmon polaritons, the formation of self-organizing subwavelength periodic structures with a period of 250 nm was observed. The minimum pulse energy at which recording occurs without surface ablation has been revealed. Keywords: direct laser recording, femtosecond laser pulses, silica, nanogratings.
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27

Mir, Hanan, Fabian Meyer, Andreas A. Brand, Katrin Erath-Dulitz, and Jan Frederik Nekarda. "Study of GHz-Burst Femtosecond Laser Micro-Punching of 4H-SiC Wafers." Solid State Phenomena 344 (June 6, 2023): 29–33. http://dx.doi.org/10.4028/p-q6725d.

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The micromaching of silicon carbide using femtosecond laser pulses is becoming an important field of research. High-repetition-rate sub-pulse trains, so-called pulse bursts, are a particularly promising route towards completely new process regimes. We report on the results of micro-punching n-type 4H-silicon carbide wafers using GHz pulse burst in order to systematically investigate the influence of the temporal energy distribution on laser processing. Pulse-burst experiments are performed at a laser wavelength of λ= 1030 nm using a single GHz burst containing a varying number of pulses and th
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28

Arkhipov M. V., Arkhipov R. M., and Rosanov N. N. "Generation of unipolar pulses of terahertz radiation with a large electric area." Optics and Spectroscopy 130, no. 8 (2022): 980. http://dx.doi.org/10.21883/eos.2022.08.54771.3703-22.

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A physical situation is proposed and theoretically analyzed, in which, in our opinion, it is possible to generate unipolar terahertz pulses with a large electric area. In this case, the gas in the tube is excited by a femtosecond IR laser pulse. In this case, the tube with gas is placed in a constant external electric field. The generation of a unipolar pulse is based on "three-step scheme" --- ionization of gas atoms by a femtosecond pulse, subsequent acceleration of a free electron in a dc external field and subsequent annihilation of an electron upon collision with a tube
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29

Ghaforyan, H., R. Sadighi-Bonabi, and E. Irani. "The Effect of Chirped Intense Femtosecond Laser Pulses on the Argon Cluster." Advances in High Energy Physics 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/2609160.

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The interaction of intense femtosecond laser pulses with atomic Argon clusters has been investigated by using nanoplasma model. Based on the dynamic simulations, ionization process, heating, and expansion of a cluster after irradiation by femtosecond laser pulses at intensities up to 2×1017 Wcm−2are studied. The analytical calculation provides ionization rate for different mechanisms and time evolution of the density of electrons for different pulse shapes. In this approach, the strong dependence of laser intensity, pulse duration, and laser shape on the electron energy, the electron density,
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30

Kuzmin E. V. and Klekovkin A.V. "Features of structuring and ablation of thin titanium films by femtosecond laser pulses." Optics and Spectroscopy 130, no. 4 (2022): 412. http://dx.doi.org/10.21883/eos.2022.04.53727.66-21.

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The processes of structuring and ablation of a titanium film by femtosecond laser pulses at wavelengths of 515 nm and 1030 nm have been studied in both single-pulse and multi-pulse modes. The optimal energy regimes for the selective removal of film material without damaging the substrate, as well as the regimes for the generation of the periodic structures on the surface, are determined. The evolution of periodic structures with an increase in the number of laser pulses is shown. The precision removal of titanium film is associated with thermomechanical explosive boiling and the corresponding
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31

Shi, Wei, Lei Yang, Lei Hou, Zenan Liu, Nuo Xu, and Zhiyang Xing. "Positive and Negative Symmetric Pulses with Fast Rising Edge Generated from a GaAs Photoconductive Semiconductor Switch." Applied Sciences 9, no. 2 (2019): 358. http://dx.doi.org/10.3390/app9020358.

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In this paper, the positive and negative symmetric pulses with a fast rising edge were generated by a GaAs photoconductive semiconductor switch (PCSS). When the GaAs PCSS was biased at 2.0 kV and triggered by a femtosecond laser pulse with a pulse energy of 97.5 J, the peak voltages of the positive and negative pulses were 1.313 kV and 1.329 kV, respectively, and the rise times were 174 ps and 164 ps, respectively. Moreover, the GaAs PCSS presents good stability. The experimental results show that GaAs PCSSs can meet the requirement of a femtosecond streak camera.
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32

Tollerud, Jonathan Owen, Giorgia Sparapassi, Angela Montanaro, et al. "Femtosecond covariance spectroscopy." Proceedings of the National Academy of Sciences 116, no. 12 (2019): 5383–86. http://dx.doi.org/10.1073/pnas.1821048116.

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The success of nonlinear optics relies largely on pulse-to-pulse consistency. In contrast, covariance-based techniques used in photoionization electron spectroscopy and mass spectrometry have shown that a wealth of information can be extracted from noise that is lost when averaging multiple measurements. Here, we apply covariance-based detection to nonlinear optical spectroscopy, and show that noise in a femtosecond laser is not necessarily a liability to be mitigated, but can act as a unique and powerful asset. As a proof of principle we apply this approach to the process of stimulated Raman
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33

Qi, Li Tao, and Jin Ping Hu. "Experimental Investigation on Femtosecond Laser Ablation of Polycarbonate." Advanced Materials Research 652-654 (January 2013): 2359–62. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.2359.

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In this paper, experimental investigations on femtosecond laser (pulse duration:164 fs, wavelength:780 nm) micromachining of polycarbonate have been carried out in air. The lateral and vertical machining precision was evaluated by scanning electron microscopy and profilometer. The morphological changes were observed by scanning electron microscopy. The ablation mechanism varied with the laser pulse energy was discussed. The diameter and depth of the ablated crated are influenced by the laser pulse energy and the number of laser pulses. The relation between the diameter and ablation depth of th
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34

Shayeganrad, Gholamreza, Martynas Beresna, Thalia Domínguez Bucio, Gilberto Brambilla, and Fredric Y. Gardes. "Tuning refractive index change of SiNx induced by ultrafast laser pulses." EPJ Web of Conferences 307 (2024): 02021. http://dx.doi.org/10.1051/epjconf/202430702021.

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We demonstrate the feasibility of femtosecond laser pulses to tune refractive index of SiNx, enabling direct writing waveguides in SiNx and reconfiguring microring resonators. The refractive index increases with pulse energy and pulse density.
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35

Hassan, Mohammed T., Haihua Liu, John Spencer Baskin, and Ahmed H. Zewail. "Photon gating in four-dimensional ultrafast electron microscopy." Proceedings of the National Academy of Sciences 112, no. 42 (2015): 12944–49. http://dx.doi.org/10.1073/pnas.1517942112.

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Ultrafast electron microscopy (UEM) is a pivotal tool for imaging of nanoscale structural dynamics with subparticle resolution on the time scale of atomic motion. Photon-induced near-field electron microscopy (PINEM), a key UEM technique, involves the detection of electrons that have gained energy from a femtosecond optical pulse via photon–electron coupling on nanostructures. PINEM has been applied in various fields of study, from materials science to biological imaging, exploiting the unique spatial, energy, and temporal characteristics of the PINEM electrons gained by interaction with a “si
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36

Zhang, Yun, Yu Xia, Canneng Liang, et al. "Investigating the Influence of Laser Polarization on Filamentation Thresholds in Transparent Media via Supercontinuum Coherence." Sensors 25, no. 7 (2025): 2285. https://doi.org/10.3390/s25072285.

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In this work, we experimentally investigate the characteristics of supercontinuum (SC) generation induced by femtosecond laser pulses with different polarization states in transparent medium. We employ a Mach–Zehnder Interferometer (MZI) to capture interference patterns during the filamentation process. The relative filamentation threshold, Pth, is measured for femtosecond laser pulses with different polarization states. The results demonstrate that the intensity of SC is strongly correlated with the polarization state of the incident laser pulses. At the same pulse energy, circularly polarize
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37

Tikhomirov, S. A. "Femtosecond System with Pulse Pumping of Seed Laser and Amplifier by Using a Single Power Unit." Devices and Methods of Measurements 12, no. 1 (2021): 23–29. http://dx.doi.org/10.21122/2220-9506-2021-12-1-23-29.

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For several decades development of methods for generating ultrashort pulses has been an independent urgent scientific and technical problem. There is a constant improvement both in the methods of such pulses receiving and in methods of their use. The aim of this work was to investigate the possibility of realizing the coordinated operation of two fundamentally different types of pump lasers for the femtosecond oscillator and amplifier based on one single-lamp laser head and to create on this basis a compact high-power femtosecond system with pulsed pumping and one power unit.The practical impl
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38

Balachninaitė, O., J. Skruibis, A. Matijošius, and V. Vaičaitis. "Temporal and spatial properties of plasma induced by infrared femtosecond laser pulses in air." Plasma Sources Science and Technology 31, no. 4 (2022): 045001. http://dx.doi.org/10.1088/1361-6595/ac5c62.

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Abstract Space and time-resolved electron density and temperature of the plasma, created in air by focused femtosecond laser pulses have been investigated as a function of the pump pulse energy and duration. For the air ionization the infrared (1030 nm) femtosecond (190–500 fs) Yb:KGW laser pulses of up to 1 mJ energy were used. Based on the Stark broadening of the oxygen-I 777.19 nm line we have found that after establishing a local equilibrium the density of laser-created plasma could exceed 1017 cm−3 with the electron temperature of over 5000 °C. Obtained results agree well with the results
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39

Qi, Li Tao, and Jin Ping Hu. "Femtosecond Laser Micromachining of High Quality Groove on Sapphire Surface." Applied Mechanics and Materials 217-219 (November 2012): 2213–16. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.2213.

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In this paper, high quality grooves were fabricated by femtosecond laser pulse on sapphire surface. Grooves were fabricated under different experimental conditions. The lateral and vertical machining precision was evaluated by scanning electron microscopy and profilometer. High quality grooves could be obtained at the condition of low pulse energy, high scanning-speed and increasing the number of laser scans. The relationship between the width and depth of the groove and the key parameters of femtosecond laser micromachining system was studied. Several samples of the high quality grooves were
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40

Liu, Yongshan, Houyi Cheng, Pierre Vallobra, et al. "Ultrafast single-pulse switching of Tb-dominant CoTb alloy." Applied Physics Letters 122, no. 2 (2023): 022401. http://dx.doi.org/10.1063/5.0131716.

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Single-pulse magnetization switching by femtosecond laser pulses is the fastest way to manipulate magnetization. To date, among rare-earth transition metal alloys, single-pulse switching is limited to Gd-based structures. Here, we demonstrate ultrafast single-pulse switching of Tb-dominant CoTb alloys within several tens of picoseconds. Our further analysis shows that the ultrafast magnetization reversal is linked to ultrafast heating of laser pulses and an external field.
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41

JIANG, YUQIANG, CUNGEN MA, ISAMU OH, YOICHIROH HOSOKAWA, and HIROSHI MASUHARA. "SECONDARY CONVERGENCE IN FEMTOSECOND LASER TRAPPING." Modern Physics Letters B 24, no. 16 (2010): 1739–46. http://dx.doi.org/10.1142/s0217984910024110.

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When femtosecond laser pulses pass through a trapped polystyrene bead, water breakdown is induced even though the energy of laser pulse is much lower compared to the threshold value of breakdown when the femtosecond laser directly irradiates in water. This mechanism is assigned to the secondary convergence of the laser by the trapped bead.
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42

Yang, Jinfeng, Kazuki Gen, Nobuyasu Naruse, Shouichi Sakakihara, and Yoichi Yoshida. "A Compact Ultrafast Electron Diffractometer with Relativistic Femtosecond Electron Pulses." Quantum Beam Science 4, no. 1 (2020): 4. http://dx.doi.org/10.3390/qubs4010004.

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We have developed a compact relativistic femtosecond electron diffractometer with a radio-frequency photocathode electron gun and an electron lens system. The electron gun generated 2.5-MeV-energy electron pulses with a duration of 55 ± 5 fs containing 6.3 × 104 electrons per pulse. Using these pulses, we successfully detected high-contrast electron diffraction images of single crystalline, polycrystalline, and amorphous materials. An excellent spatial resolution of diffraction images was obtained as 0.027 ± 0.001 Å−1. In the time-resolved electron diffraction measurement, a laser-excited ultr
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43

Nan, Junyi, Min Li, Ling Zhang, Shuai Yuan, Boqu He, and Heping Zeng. "Terahertz and Photoelectron Emission from Nanoporous Gold Films on Semiconductors." Nanomaterials 9, no. 3 (2019): 419. http://dx.doi.org/10.3390/nano9030419.

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Efficient terahertz and photoelectron emission were observed from nano-porous gold (NPG) films deposited on an intrinsic gallium arsenide (GaAs) semiconductor substrate stimulated by femtosecond laser with pulse width of 60 fs. Time-domain THz emission and reflection spectroscopy confirmed that the free charges accelerated by irradiated femtosecond laser pulses transferred from the NPG films into the GaAs substrates. Accordingly, charges accumulation was reduced in the NPG films, resulting in a stronger emission of THz pulse than that from NPG films deposited on SiO2 substrate. Charges injecte
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44

Peiyu, Xia, Lu Faming, Ishii Nobuhisa, Kanai Teruto та Itatani Jiro. "Generation of sub-two-cycle CEP-stable optical pulses at 3.5 μm by multiple-plate pulse compression for high-harmonic generation in crystals". EPJ Web of Conferences 205 (2019): 01006. http://dx.doi.org/10.1051/epjconf/201920501006.

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Multiple-plate pulse compression of femtosecond mid-infrared pulses is demonstrated using YAG and Si windows. With this robust compression scheme, we produce sub-two-cycle, CEP-stable optical pulses and observe CEP-dependent high harmonic generation in crystals.
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45

Shaheen, Mohamed E., and Brian J. Fryer. "Femtosecond laser ablation of brass: A study of surface morphology and ablation rate." Laser and Particle Beams 30, no. 3 (2012): 473–79. http://dx.doi.org/10.1017/s0263034612000407.

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AbstractThe interaction of near infrared femtosecond laser pulses with a Cu based alloy (brass) in ambient air at atmospheric pressure and under different laser conditions was investigated. The effects of laser fluence and number of pulses on surface morphology and ablation rate were studied using scanning electron microscopy (SEM) and optical microscopy. Ablation rates were found to rapidly increase from 83 to 604 nm/pulse in the fluence range 1.14–12.21 J/cm2. At fluence >12.21 J/cm2, ablation rates increased slowly to a maximum (607 nm/pulse at 19.14 J/cm2), and then decreased at fluence
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46

Milchberg, H. M., K. Y. Kim, V. Kumarappan, B. D. Layer, and H. Sheng. "Clustered gases as a medium for efficient plasma waveguide generation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1840 (2006): 647–61. http://dx.doi.org/10.1098/rsta.2005.1729.

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Clustered gas jets are shown to be an efficient means for plasma waveguide generation, for both femtosecond and picosecond generation pulses. These waveguides enable significantly lower on-axis plasma density (less than 10 18 cm −3 ) than in conventional hydrodynamic plasma waveguides generated in unclustered gases. Using femtosecond pump pulses, self-guided propagation and strong absorption (more than 70%) are used to produce long centimetre scale channels in an argon cluster jet, and a subsequent intense pulse is coupled into the guide with 50% efficiency and guided at above 10 17 W cm −2 in
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47

Sitnikov, Dmitry S., Maxim A. Filatov, and Inna V. Ilina. "Optimal Exposure Parameters for Microsurgery of Embryo Zona Pellucida Using Femtosecond Laser Pulses." Applied Sciences 13, no. 20 (2023): 11204. http://dx.doi.org/10.3390/app132011204.

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We applied femtosecond laser pulses for microsurgery of the zona pellucida (ZP) of mouse embryos in terms of assisted reproductive technologies. The embryos were subjected to a series of laser pulses (wavelength of 514 nm, pulse duration of 280 fs, repetition rate of 2.5 kHz). Optical microscopy was used to study the dependence of the ZP cut width on the pulse energy E and velocity v of the laser beam. It is shown that the same value of the cut width can be obtained for different combinations of these parameters. The boundaries of admissible values were found to be E = (19–52) nJ, v = (0.001–0
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48

Zhang, Lei, Xiao Wen Cao, Shun Guang Li, Ru Yi Xiang, and Hui Chao Sun. "Investigation of Femtosecond Laser Ablation Threshold for Nickel Template." Applied Mechanics and Materials 633-634 (September 2014): 665–70. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.665.

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This paper presents a theoretical and experimental investigation into the ablation threshold of nickel template by femtosecond laser in air at atmospheric pressure. The laser pulses used for the study are 800 nm in wavelength, 100fs in pulse duration, and 1KHz in repetition rate. The two-temperature model is used to predict the single-pulse ablation threshold for nickel theoretically. Micro-hole ablation experiments are carried out in air by focusing the femtosecond laser beam on the nickel target surface at normal incidence with the long-focus objective lens of enlargement factor 50 and NA=0.
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49

Nedyalkov, N., A. Dikovska, T. Dilova, and G. Atanasova. "Influence of the pulse duration at the laser processing of nitride ceramics." Journal of Physics: Conference Series 2710, no. 1 (2024): 012014. http://dx.doi.org/10.1088/1742-6596/2710/1/012014.

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Abstract This paper presents results on laser ablation of AlN and Si3N4 ceramics by laser pulses with different duration. Three types of laser systems, a Nd:YAG one, operated at wavelength of 1064 nm and pulse duration of 15 ns, a Nd:YAG, operated at wavelength of 1064 nm and pulse duration of 10 ps, and a femtosecond laser system, operated at 800 nm, with a pulse duration of 75 fs, are used for experiments. Details on the ablation efficiency, surface morphology, and the chemical composition of the irradiated zones as a function of the pulse duration are given and discussed. It is demonstrated
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50

Брехов, К. А., К. А. Гришунин, Д. В. Афанасьев та ін. "Генерация второй оптической гармоники и ее фотоиндуцированная динамика в сегнетоэлектрике-полупроводнике Sn-=SUB=-2-=/SUB=-P-=SUB=-2-=/SUB=-S-=SUB=-6-=/SUB=-". Физика твердого тела 60, № 1 (2018): 33. http://dx.doi.org/10.21883/ftt.2018.01.45285.179.

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AbstractBy means of optical pump–probe technique, the ultrafast dynamics of nonlinear optical response of the ferroelectric semiconductor Sn_2P_2S_6 crystal excited with a femtosecond laser pulse has been investigated. It has been shown that, under the action of femtosecond pulses, change in optical second harmonic generation occurs in the sample, which can be due to screening of existing electric polarization.
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