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Showing papers on "Femtosecond published in 1997"


Journal ArticleDOI
03 Jan 1997-Science
TL;DR: In this paper, the earliest events associated with excited-state relaxation in tris-(2,2′-bipyridine)ruthenium(II) were observed to occur in ∼300 femtoseconds after the initial excitation.
Abstract: Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the earliest events associated with excited-state relaxation in tris-(2,2′-bipyridine)ruthenium(II). The data reveal dynamics associated with the temporal evolution of the Franck-Condon state to the lowest energy excited state of this molecule. The process is essentially complete in ∼300 femtoseconds after the initial excitation. This result is discussed with regard to reformulating long-held notions about excited-state relaxation, as well as its implication for the importance of non-equilibrium excited-state processes in understanding and designing molecular-based electron transfer, artificial photosynthetic, and photovoltaic assemblies in which compounds of this class are currently playing a key role.

642 citations


Journal ArticleDOI
Hrvoje Petek1, S. Ogawa1
TL;DR: Femtosecond time-resolved two-photon photoemission has attracted particularly strong interest because it incorporates many of the surface analytical capabilities of photo-emission and inverse photo emission, with time-resolution approaching the fundamental response of electrons to optical excitation as mentioned in this paper.

591 citations


Journal ArticleDOI
24 Oct 1997-Science
TL;DR: In this article, an x-ray supercontinuum was generated at a repetition rate of 1 kilohertz by focusing 5-femtosecond near-infrared (780 nm) laser pulses into a helium gas jet.
Abstract: Coherent extreme-ultraviolet radiation extending to wavelengths below the carbon K edge at 4.37 nanometers (nm) has been generated at a repetition rate of 1 kilohertz by focusing 5-femtosecond near-infrared (780 nm) laser pulses into a helium gas jet. The incident light field performs just a few oscillations, which results in the emission of an x-ray supercontinuum rather than discrete harmonics. Owing to the extremely short rise time of the driving pulses, neutral atoms can be exposed to high fields before they are depleted by ionization. As a result, the observed x-ray radiation extends well into the water window and is delivered in a well-collimated beam (divergence less than 1 milliradian). The high repetition rate and spatial coherence result in a brightness of about 5 × 108 photons per square millimeter per square milliradian per second in a 1-percent bandwidth at 4.37 nm, the carbon edge of the water window. The compact laboratory system holds promise as a source for biological holography and nonlinear optics in the x-ray regime.

562 citations


Journal ArticleDOI
TL;DR: Femtosecond pulses with center wavelengths between 470 and 750 nm are generated in a single-stage type I BBO optical parametric amplifier pumped by a frequency-doubled 1-kHz Ti:sapphire amplifier.
Abstract: Femtosecond pulses with center wavelengths between 470 and 750 nm are generated in a single-stage type I BBO optical parametric amplifier pumped by a frequency-doubled 1-kHz Ti:sapphire amplifier. A high-quality white-light continuum is used as the seed. Pulse durations as short as 16 fs and pulse energies of as much as 11 microJ are observed. The quantum efficiency is ~25% for both 7- and 40-microJ pump pulses. This unique combination of ultrashort pulse duration and high conversion is made possible by noncollinear phase matching that permits a sufficiently large amplification bandwidth. Simultaneously the group velocities of the signal and the idler are effectively matched. As a result widely tunable sub-20-fs pulses can be generated in a nonlinear crystal as thick as 2 mm.

561 citations


Journal ArticleDOI
24 Oct 1997-Science
TL;DR: A femtosecond mid-infrared pump-probe study of the vibrational and orientational dynamics of the OH-stretching mode of HDO dissolved in D2O is presented in this article.
Abstract: A femtosecond mid-infrared pump-probe study of the vibrational and orientational dynamics of the OH-stretching mode of HDO dissolved in D2O is presented. The orientational relaxation of the HDO molecules was observed to occur on either a very slow or a very fast time scale, with associated time constants of τ R = 13 picoseconds and τ R = 0.7 picosecond. It was observed that strongly hydrogen-bonded water molecules only relax through the slow orientational relaxation process, whereas the fast process dominates for weakly hydrogen-bonded molecules. This suggests that, with respect to orientional dynamics, two distinct molecular species exist in liquid water.

527 citations


Journal ArticleDOI
TL;DR: In this paper, a computer-controlled acousto-optic pulse shaper and a genetic algorithm were used to optimize population transfer from ground to first excited state in a molecular system.

498 citations


Journal ArticleDOI
04 Dec 1997-Nature
TL;DR: In this paper, the authors studied the response of a Langmuir-Blodgett multilayer film of cadmium arachidate to laser heating by observing changes in the intensity of one Bragg peak for different delays between the perturbing optical pulse and the X-ray probe pulse.
Abstract: The extension of time-resolved X-ray diffraction to the subpicosecond domain is an important challenge, as the nature of chemical reactions and phase transitions is determined by atomic motions on these timescales. An ultimate goal is to study the structure of transient states with a time resolution shorter than the typical period of vibration along a reaction coordinate (around 100 fs). Biological processes that can be initiated optically have been studied extensively by ultrafast infrared, visible and ultraviolet spectroscopy1. But these techniques probe only electronic states, whereas time-resolved crystallography should be able to directly monitor atomic positions. Here we show that changes in the X-ray diffraction pattern from an organic film heated by a laser pulse can be monitored on a timescale of less than a picosecond. We have studied the response of a Langmuir–Blodgett multilayer film of cadmium arachidate to laser heating by observing changes in the intensity of one Bragg peak for different delays between the perturbing optical pulse and the X-ray probe pulse. A strong decrease in intensity is seen within a picosecond of heating, resulting from disorder introduced to the layers of cadmium atoms before thermal expansion of the film (which ultimately leads to its destruction) has time to occur.

396 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the physical processes which come into play in laser-solid interaction on the ultrafast time scale open new routes of modifying the structure and the morphology of materials and offer interesting perspectives in laser materials processing.

391 citations


Journal ArticleDOI
TL;DR: Femtosecond transient absorption measurements of the photoisomerization of azobenzene excited at 435 nm in the long-wavelength formation with a dominating 170 fs and a weak 2 ps component are found.

350 citations


Journal ArticleDOI
TL;DR: In this article, a programmable liquid crystal light modulator is used to compress femtosecond laser pulses using an evolutionary algorithm, and the second harmonic light (SHG) signal is maximized by the algorithm.
Abstract: We report on computer controlled compression of femtosecond laser pulses using a programmable liquid crys- tal spatial light modulator which is feedback-controlled by an evolutionary algorithm. This algorithm generates the opti- mal laser field on the basis of feedback from the experiment by optimizing the laser pulse iteratively. Without knowledge of the (chirped) input pulses, the experimental signal (second harmonic light=SHG) is maximized by the algorithm, thus re- sulting in fully compressed pulses. This method only makes use of the experiment's response (SHG signal) on the formed pulses. No other parameters need to be considered. This ap- proach leads to many experimental applications in all fields of optics and ultrafast spectroscopy where particularly shaped pulses are advantageous.

342 citations


Journal ArticleDOI
TL;DR: In this paper, the vibrational cooling of azobenzene after photoisomerization was investigated by time resolved IR spectroscopy with femtosecond time resolution, and the experimental data were discussed in terms of a simple theoretical model which was derived in order to account for the off-diagonal anharmonicity between the investigated highfrequency modes and the bath of the remaining low-frequency modes in polyatomic molecules.
Abstract: The vibrational cooling of azobenzene after photoisomerization is investigated by time resolved IR spectroscopy with femtosecond time resolution. Transient difference spectra were obtained in a frequency range where phenyl ring modes and the central N=N-stretching mode absorbs. The experimental data are discussed in terms of a simple theoretical model which was derived in order to account for the off-diagonal anharmonicity between the investigated high-frequency modes and the bath of the remaining low-frequency modes in a polyatomic molecule. It is shown that these off-diagonal anharmonic constants dominate the observed transient absorbance changes while the anharmonicity of the high-frequency modes themselves (diagonal anharmonicity) causes only minor effects. Based on the transient IR spectra, the energy flow in the azobenzene molecule can be described as follows: After an initial ultrafast intramolecular energy redistribution process, the decay of the related intramolecular temperature occurs via intermolecular energy transfer to the solvent on a time scale of ca. 20 ps.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the spectral changes that occur when unfocused femtosecond pulses at 800 nm propagate through different atomic and molecular gases, and found that the observed red shift in the self-phase modulated spectra after propagation through N2, O2, and air is attributed to a delayed change of the nonlinear refractive index, a consequence of the molecular response to impulsive excitation of rotational coherences.
Abstract: We analyze the spectral changes that occur when unfocused intense femtosecond pulses at 800 nm propagate through different atomic and molecular gases. The observed red shift in the self-phase-modulated spectra after propagation through N2, O2, and air is attributed to a delayed change of the nonlinear refractive index, a consequence of the molecular response to impulsive excitation of rotational coherences. We compare these results on the nonlinear refractive index with those obtained from Ar, Xe, and SF6.

Journal ArticleDOI
TL;DR: In this article, a large and good-optical-quality crystal of gadolinium and calcium oxoborate, Ca4GdO(BO3)3 (GdCOB), has been grown from a melt by the Czochralski pulling method.
Abstract: Large and good-optical-quality crystals of gadolinium and calcium oxoborate, Ca4GdO(BO3)3 (GdCOB) have been grown from a melt by the Czochralski pulling method. The crystal is absolutely insensitive to moisture. Linear- and quadratic nonlinear-optical properties of this new monoclinic biaxial borate crystal are reported. The crystal is transparent in the visible and the near IR (from 0.32 to 2.7 µm), with favorable phase matching conditions for second-harmonic generation. Experimental phase-matching results, measured with a femtosecond broadband pulse parametric generator source tunable from 0.8 to 2.100 µm, are compared with theoretical predictions. The effective nonlinear coefficients are determined, leading to deff=1 pm/V for type I crystals in the ZX plane. The damage threshold is as high as 1 GW/cm2 at 0.532 µm. The second-harmonic generation conversion efficiency of a Q-switched Nd:YAG laser with a 15-mm long crystal is greater than 50%. These values together with the possibility of growing large crystals make GdCOB an excellent candidate for the next generation of crystals for frequency conversion and parametric processes.

Journal ArticleDOI
TL;DR: The power limitations should be considered during NIR femtosecond microscopy of vital cells and in the design of compact NIR FemTosecond solid-state lasers for two-photon microscopes.
Abstract: The influence of femtosecond near-infrared (NIR) microirradiation on cell vitality and cellular reproduction has been studied. Chinese hamster ovary cells exposed to a highly focused 150-fs scanning beam at 730, 760, and 800 nm (80 MHz, 80-mus pixel dwell time) of /=6 -mW mean power, cells were unable to form clones. They died or became giant cells. Complete cell destruction, including cell fragmentation, occurred at mean powers >10 mW. Cell death was accompanied by intense luminescence in the mitochondrial region. When we consider the diffraction-limited spot size in the submicrometer region, intensities and photon flux densities of 0.8-kW pulses (10-mW mean power) are of the order of terawatts per square centimeter (10(12)W/cm (2)) and 10(32) photons cm(-2) s(-1) , respectively. Extremely high fields may induce destructive intracellular plasma formation. The power limitations should be considered during NIR femtosecond microscopy of vital cells and in the design of compact NIR femtosecond solid-state lasers for two-photon microscopes.

Journal ArticleDOI
TL;DR: A practical adaptive method for femtosecond optical pulse compression that is robust and capable of handling the general case of pulse compression, in which the input pulses are completely uncharacterized or partially characterized.
Abstract: A practical adaptive method for femtosecond optical pulse compression is demonstrated experimentally for the first time to our knowledge. The method is robust and capable of handling the general case of pulse compression, in which the input pulses are completely uncharacterized or partially characterized.

Journal ArticleDOI
TL;DR: In this article, the two-photon response of a GaAsP photodiode was characterized using a femtosecond Ti:sapphire laser tuned below the diode bandgap.
Abstract: We experimentally characterize the two-photon response of a GaAsP photodiode by use of a femtosecond Ti:sapphire laser tuned below the diode bandgap. The photodiode is shown to be highly suitable for real-time second-order autocorrelation measurements of pulses as short as 6fs in duration and with energies as small as a few picojoules.

Journal ArticleDOI
TL;DR: In this paper, a compact all-solid-state femtosecond Ti:sapphire oscillator-amplifier system using no grating-based pulse stretcher produces 20-fs, 1.5mJ pulses at a 1-kHz repetition rate.
Abstract: A compact all-solid-state femtosecond Ti:sapphire oscillator–amplifier system using no grating-based pulse stretcher produces 20-fs, 1.5-mJ pulses at a 1-kHz repetition rate. The pulses are subsequently compressed in a hollow-fiber chirped-mirror compressor. The system delivers bandwidth-limited 5-fs, 0.5-mJ pulses at 780 nm in a diffraction-limited beam.

Journal ArticleDOI
13 Mar 1997-Nature
TL;DR: In this article, a femtosecond (fs) time resolution in spectroscopic experiments is used to study the evolution of nuclear motions in chemical and photobiochemical reactions.
Abstract: With the advent of femtosecond (fs) time resolution in spectroscopic experiments, it is now possible to study the evolution of nuclear motions in chemical and photobiochemical reactions. In general, the reaction is clocked by an initial fs laser pulse (which establishes a zero of time) and the dynamics are probed by a second fs pulse; the detection methods include conventional and photoelectron spectroscopy and mass spectrometry. Replacing the probe laser with electron pulses offers a means for imaging ultrafast structural changes with diffraction techniques, which should permit the study of molecular systems of greater complexity (such as biomolecules). On such timescales, observation of chemical changes using electron scattering is non-trivial, because space-charge effects broaden the electron pulse width and because temporal overlap of the (clocking) photon pulse and the (probe) electron pulse must be established. Here we report the detection of transient chemical change during molecular dissociation using ultrafast electron diffraction. We are able to detect a change in the scattered electron beam with the zero of time established unambiguously and the timing of the changes clocked in situ. This ability to clock changes in scattering is essential to studies of the dynamics of molecular structures.

Journal ArticleDOI
TL;DR: In this paper, femtosecond pump-probe experiments are combined with computer simulations using the recently established crystal structure of these systems to assess the nature of excitation motion.
Abstract: We have studied excitation energy transfer in the photosynthetic antenna systems LH1 and LH2 of purple bacteria. Femtosecond pump−probe experiments are combined with computer simulations using the recently established crystal structure of these systems to assess the nature of excitation motion. We have measured the transient absorption kinetics and spectra of the LH1 and LH2 complexes in the temperature range from 4.2 to 296 K with femtosecond time resolution. The calculations based on the Pauli master equation disagreed with experimentally measured population and anisotropy kinetics, suggesting that the simple model of excitation hopping between bacteriochlorophyll a molecules is not a proper description for energy transport in LH1 and LH2. As a next step we have used the exciton theory to reproduce the transient absorption spectra of LH2, and we found that the coherence length of the exciton in B850 of LH2 1.5 ps after excitation of B800 is 4 ± 1.

Journal ArticleDOI
C. Winnewisser1, P. Uhd Jepsen1, M. Schall1, V. Schyja1, Hanspeter Helm1 
TL;DR: In this paper, the phase retardation (PR) of an infrared femtosecond probe pulse is measured in LiTaO3, LiNbO3 and ZnTe and compared with theoretical calculations for the PR signal.
Abstract: Freely propagating THz pulses are detected in electro-optic (eo) crystals by monitoring the phase retardation (PR) of an infrared femtosecond probe pulse. This technique permits the determination of the temporal shape of the THz pulse in the subpicosecond time domain. We present measurements in LiTaO3, LiNbO3, and ZnTe and compare their signal performance as eo crystals with theoretical calculations for the PR signal. ZnTe shows the best performance for eo detection.

Journal ArticleDOI
TL;DR: In this paper, the role of the relative thickness of the interaction region as dictated by the acousto-optic Q parameter was analyzed and it was shown that varying Q allows flexibility in choosing between diffraction efficiency and pixels of resolution.
Abstract: We focus theoretically and experimentally on the fundamental limitations of spectral pulse shaping using an acousto-optic modulator. We analyze the role of the relative thickness of the interaction region as dictated by the acousto-optic Q parameter and show that varying Q allows flexibility in choosing between diffraction efficiency and pixels of resolution. We model and experimentally demonstrate the effects of potential nonidealities such as nonlinear acoustic attenuation. In addition, we derive a simple and intuitive expression to predict the magnitude of the distortions in the spatial profile generated by an acousto-optic-modulator spectral light modulator. Finally, we demonstrate amplification of acousto-optic-modulator-generated shaped pulses for the first time.

Journal ArticleDOI
TL;DR: In this article, the spectral broadening by propagation along hollow-core fused silica fiber filled with atomic and molecular gases is studied under two excitation regimes with high-energy input pulses of 140 fs and 20 fs duration respectively.
Abstract: Powerful techniques for spectral broadening and ultrabroadband dispersion control, which allow the compression of high-energy femtosecond pulses to a duration of a few optical cycles, are presented. Spectral broadening by propagation along hollow-core fused silica fiber filled with atomic and molecular gases is studied under two excitation regimes with high-energy input pulses of 140 fs and 20 fs duration respectively. Conditions for optimum pulse compression are outlined considering the role of self-phase modulation and gas dispersion in the two regimes. With 20 fs input pulses and under optimum compression conditions we demonstrate a pulse shortening down to 4.5 fs with output energy up to 70 μJ using a high-throughput prism-chirped-mirror delay line. These pulses are the shortest generated to date at multigigawatt peak power. PACS: 42.65.Re; 42.65.Vh Ultrashort-pulse lasers are the most important experimental tools for investigating fast-evolving atomic and molecular dynamics in physics, chemistry, and biology. In the last few years, great technological advances have been made in the field of ultrafast pulse generation. New mode-locking techniques such as additive-pulse mode-locking and Kerr-lens mode-locking have been successfully used for femtosecond pulse generation from a wide range of solid-state laser oscillators [1]. Using chirped mirrors [2] for intracavity dispersion control, pulses down to 7.5 fs have been directly generated by a Kerr-lens mode-locked Ti:sapphire oscillator [3] and, more recently, 6.5-fs pulses have been obtained using broadband semiconductor saturable absorbers for self-starting [4]. Ti:sapphire amplifiers seeded by femtosecond laser oscillators can now generate pulses of 20–30 fs with gigawatt [5, 6] or terawatt [7–9] peak power at repetition rates in the kHz and 10 Hz regimes, respectively. Ultrashort pulses can also be generated by extracavity compression techniques, in which the pulses are spectrally broadened upon propagation in a suitable nonlinear waveguide and subsequently compressed in a carefully designed optical dispersive delay line. Spectral broadening of laser pulses by self-phase modulation (SPM) in a single-mode optical fiber is a well-established technique: pulses down to 6 fs were obtained in 1987 from 50-fs pulses from a mode-locked dye laser [10]. More recently 13-fs pulses from a cavity-dumped Ti:sapphire laser were compressed to 5 fs with the same technique [11]. However, the use of single-mode fibers limits the pulse energy to a few nanojoules. A powerful pulse compression technique based on spectral broadening in an hollow fiber filled with noble gases has demonstrated the capability of handling highenergy pulses (sub-mJ range) [12]. This technique presents the advantages of a guiding element with a large diameter mode and of a fast nonlinear medium with high threshold for multiphoton ionization. New concepts in the construction of dispersive delay lines have been applied in the development of specially designed chirped mirrors for fine control of cubic and quartic phase dispersion terms over a large spectral bandwidth [3]. The implementation of the hollow-fiber technique using 20-fs seed pulses from a Ti:sapphire system [5] and a high-throughput broadband dispersive delay line consisting of prisms and chirped mirrors has recently permitted the generation of multigigawatt sub-5 fs pulses [13]. In this paper we present a comprehensive analysis of compression experiments with high-energy femtosecond pulses performed using gas-filled hollow fibers. Spectral broadenings obtained in different gases are compared for 140-fs and 20-fs input pulses generated by Ti:sapphire laser systems, and the optimum conditions for pulse compression are outlined considering the role of SPM and gas dispersion. A new ultrabroadband prism-chirped-mirror dispersive delay line, characterized by a high throughput and dispersion control up to the fourth order, is described in detail. The paper is organized as follows. In Sect. 1 we provide a description of hollow fiber modes and discuss the major advantages of this device compared to optical fibers. Sect. 2 reports on typical spectral broadenings achieved under different excitation conditions. In Sect. 3 we report on the characteristics of the prism-chirped-mirror compressor and discuss the experimental results obtained with 20-fs input pulses. Under optimum compression conditions we show a pulse shortening down to 4.5 fs with output energy up to 70 μJ. These pulses are the

01 Jan 1997
TL;DR: In this paper, a femtosecond code-division multiple access (CDMA) communication system test bed operating over optical fiber in the 1.5 /spl mu/m communication band is presented.
Abstract: This paper reports comprehensive experimental results on a femtosecond code-division multiple-access (CDMA) communication system test bed operating over optical fiber in the 1.5 /spl mu/m communication band. Our test bed integrates together several novel subsystems, including low-loss fiber-pigtailed pulse shapers for encoding-decoding, use of dispersion equalizing fibers in dispersion compensated links for femtosecond pulse transmission and also in femtosecond chirped pulse amplification (CPA) erbium doped fiber amplifiers (EDFAs), and high-contrast nonlinear fiber-optic thresholders. The individual subsystems are described, and single-user system level experimental results demonstrating the ability to transmit spectrally encoded femtosecond pulses over a 2.5-km dispersion compensated fiber link followed by decoding and high contrast nonlinear thresholding are presented.

Journal ArticleDOI
TL;DR: Time- and momentum-resolved two-photon photoemission spectra as a function of layer thickness fully determine the conduction band dynamics at the interface.
Abstract: ▪ Abstract Two-photon photoemission is a promising new technique that has been developed for the study of electron dynamics at interfaces. A femtosecond laser is used to both create an excited electronic distribution at the surface and eject the distribution for subsequent energy analysis. Time- and momentum-resolved two-photon photoemission spectra as a function of layer thickness fully determine the conduction band dynamics at the interface. Earlier clean surface studies showed how excited electron lifetimes are affected by the crystal band structure and vacuum image potential. Recent studies of various insulator/metal interfaces show that the dynamics of excess electrons are largely determined by the electron affinity of the adsorbate. In general, electron dynamics at the interface are influenced by the substrate and adlayer band structures, dielectric screening, and polaron formation in the two-dimensional overlayer lattice.

Journal ArticleDOI
TL;DR: Results are presented showing that, when it is used as a photodetector, a light-emitting diode (LED) has a power-dependent response that can be used for sensitive detection and characterization of picosecond and femtosecond laser pulses.
Abstract: We present results showing that, when it is used as a photodetector, a light-emitting diode (LED) has a power-dependent response that can be used for sensitive detection and characterization of picosecond and femtosecond laser pulses. A characterization of a typical LED is presented at 800 nm, and we demonstrate how this effect can be used to construct an extremely compact novel autocorrelator based on a Wollaston prism.

Journal ArticleDOI
TL;DR: In this article, a femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) was applied in order to investigate molecular dynamics in the gas phase.


Journal ArticleDOI
14 Mar 1997-Science
TL;DR: In this article, femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KTaO3 into a squeezed state, nearly periodic in time, in which the variance of the atomic displacements dips below the standard quantum limit for half of a cycle.
Abstract: Femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KTaO3 into a squeezed state, nearly periodic in time, in which the variance of the atomic displacements dips below the standard quantum limit for half of a cycle. This nonclassical state involves a continuum of transverse acoustic modes that leads to oscillations in the refractive index associated with the frequency of a van Hove singularity in the phonon density of states.

Journal ArticleDOI
TL;DR: In this article, the femtosecond pump-and-probe spectroscopy was used to detect photo-induced differential reflection in the picosecond time domain and the measured period increases linearly with size over a wide range and extracted sound velocities are consistent with those of bulk.
Abstract: Nonthermal generation of coherent-acoustic phonons is observed in metallic nanoparticles of tin and gallium, which are solid and liquid, respectively, at room temperature, by applying femtosecond pump-and-probe spectroscopy. Oscillations in the photo-induced differential reflection are clearly detected in the picosecond time domain. The measured period increases approximately linearly with size over a wide range and extracted sound velocities are consistent with those of bulk. Transition to ballistic regime in carrier excitation is also discussed on the basis of the disappearance of oscillations for particle sizes below hot-carrier mean free paths.

Journal ArticleDOI
TL;DR: Experiments on ultrashort pulses that maintain their strong lateral and longitudinal localization in a bulk linear highly dispersive medium and can be applied in femtosecond laser optics are reported.
Abstract: We report experiments on ultrashort pulses that maintain their strong lateral and longitudinal localization in a bulk linear highly dispersive medium. The diameter of the central peak and the temporal width of the field autocorrelation function of the pulses were 20 µm and 210 fs, respectively, and the spatiotemporal structure was preserved in the course of 7-cm propagation in the sample. The pulses were obtained with a computer hologram designed for generating the Bessel beam and can be applied in femtosecond laser optics.