Subpicosecond KrF* excimer-laser source

Schwarzenbach, A. P.; Luk, T. S.; McIntyre, I. A.; Johann, Ulrich; McPherson, A.; Boyer, K.; Rhodes, C. K.

doi:10.1364/ol.11.000499

Cited by 120 publications

(24 citation statements)

References 11 publications

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“…[1][2][3][4][5][6][7] The power densities of the output beams of these systems typically range from 10 to 100 GW/cm 2 . At those high power densities nonlinearoptical properties of window materials become important.…”

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“…14, No. 21 / November 1,1989 Fused Silica the best fits to the measured data assuming a two-photon absorption mechanism for fused silica and a three-photon absorption mechanism for CaF 2 , LiF, and MgF 2 -order to get information on the net effect of multiphoton absorption, the sample was illuminated only for a limited number of shots, until absorption due to colorcenter formation became important. Care was taken to collect all the transmitted energy, including the scattered part, which was distributed in a solid angle of -10-2 sr.…”

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Intensity-dependent loss properties of window materials at 248 nm

1989

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Transmission of fused silica, CaF 2 , LiF, and MgF 2 is measured using 450-fsec, 248-nm pulses in the range 10-120 GW/cm 2 . Different loss mechanisms such as scattering of transmitted radiation, color-center formation, and multiphoton absorption were studied separately. For fused silica a two-photon absorption mechanism is found, while for CaF 2 , LiF, and MgF 2 three-photon absorption and absorption due to color-center formation are found as dominant absorption mechanisms.With existing high-brightness KrF laser systems, optical powers of the order of typically 10-100 GW are generated. [1][2][3][4][5][6][7] The power densities of the output beams of these systems typically range from 10 to 100 GW/cm 2 . At those high power densities nonlinearoptical properties of window materials become important.Previous studies of two-photon absorption were performed at 355 and 266 nm. 8 Measurements of nonlinear absorption of window materials at 248 nm were recently reported in Refs. 6,9, and 10. However, the relative contributions of the different loss mechanisms (multiphoton absorption, color-center formation, and scattering) were not considered. In Ref. 8 the two-photon absorption mechanism found for fused silica was simply adapted for CaF 2 . Surprisingly, the two-photon coefficient of CaF 2 was dependent on the sample studied. Even in the case of LiF andMgF 2 , where two-photon absorption is improbable, an upper bound for a two-photon absorption coefficient was defined. In addition, the results reported in the publications cited above are not in total agreement. The above problems and the importance and necessity of having exact data led us to carry out comparative measurements on the intensity-dependent transmission of UV windows of different materials and from different suppliers. In this Letter we report on the nonlinear loss mechanisms observed in fused silica, CaF 2 , LiF, and MgF 2 using 450-fsec pulses at 248 nm. While for fused silica our results show good agreement with the two-photon absorption mechanism found in Refs. 8 and 9, we found that the data for CaF 2 , LiF, and MgF 2 cannot simply be approximated by two-photon absorption but can be described by the combined effect of three-photon absorption, scattering, and color-center formation.For the transmission measurements, 8-mJ, 450-fsec pulses at 248 nm from a high-power KrF laser system 6 were used. The pulse energy is measured with a Gentec ED-500 detector. The pulse duration is determined by an autocorrelation measurement using twophoton ionization in NO. 2 , 6 " 11 ,12 From the autocorrelation trace a +4% fluctuation is obtained for the energy and the pulse width. The amplified spontaneous emission is -5% of the total energy.The experimental setup is as follows: The relatively homogeneous middle part of the beam is selected by an approximately 3.5-mm-diameter circular aperture. The plane of this aperture is imaged onto the sample by a 1-m focal-length fused-silica lens. The spot size and the intensity distribution on the sample were checked by a linear d...

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Intensity-dependent loss properties of window materials at 248 nm

1989

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“…14,15 The availability of an ultraviolet laser technology 16,17 capable of producing subpicosecond pulses with energies approaching the joule level in low-divergence beams at high repetition rates is making possible a regime of physical study concerning the behavior of matter at extremely high intensities 18,19 in the 10 20 -10 21 -W/cm 2 range. Since it can be shown 14,15 that intensities comparable to 5x 10 19 W/cm 2 at 248 nm will cause strongly relativistic motions to occur, the use of an intensity of =10 21 W/cm 2 would then generate relativistic electrons 14,15 with an energy sufficient (/-24) to produce electrofission by the collisional mechanism represented by reaction (2).…”

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Possibility of optically induced nuclear fission

1988

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The process of nuclear fission induced by nonlinear radiative coupling to atomic electrons is considered. For 248-nm radiation at an intensity of -10 21 W/cm 2 , highly relativistic currents are produced which can couple to the fission mode of nuclear decay. With irradiation for a time of -100 fs, the results indicate a fission probability of -10 ~5 for 2 $U nuclei located at the surface of a solid target, a value several orders of magnitude above the limit of detection. PACS numbers: 25.85.Ge, 32.80.Wr Nuclear fission can be induced by electromagnetic interactions involving either photons or charged particles if sufficient energy is communicated to the nucleus enabling the system to penetrate the fission barrier. Known examples of electromagnetically induced fission are photofission, 1,2 rr-^/,+/ 2 +V72, (1) electrofission, 3 e~+A-+ fi+f 2 + fn + e~,and muon-induced fission. 4 ' 5 It has also recently been proposed 6,7 that driven motions of atomic electrons arising from intense irradiation of atoms can couple energy to nuclear transitions occurring between bound nuclear states. This latter mechanism has some features in common with processes of nuclear excitation and deexcitation in which atomic electronic transitions play a role. 8 " 13 The present work examines the possibility of optically induced nuclear fission of heavy elements arising from coupling to driven motions of atomic electrons produced by intense external radiation. The fission process is a particularly favorable one for the demonstration of nuclear excitation. It (1) generally has a large nuclear matrix element, (2) is a broad channel permitting coupling to spectral power over a wide range, and (3) involves a very large energy release comprising distinctive emissions. It will be shown that very large instantaneous fission rates may be generated in a considerable range of nuclear materials. If this can be achieved, extremely bright and spatially localized high-flux pulsed sources of fission fragments, neutrons, and y radiation could be produced (e.g., > 10 24 fission fragments/cm 2 s).The acceleration of electrons to an energy sufficient to surpass the threshold of the fission reaction can be achieved in the focal region of an intense laser pulse. 14,15 The availability of an ultraviolet laser technology 16,17 capable of producing subpicosecond pulses with energies approaching the joule level in low-divergence beams at high repetition rates is making possible a regime of physical study concerning the behavior of matter at extremely high intensities 18,19 in the 10 20 -10 21 -W/cm 2 range. Since it can be shown 14,15 that intensities comparable to 5x 10 19 W/cm 2 at 248 nm will cause strongly relativistic motions to occur, the use of an intensity of =10 21 W/cm 2 would then generate relativistic electrons 14,15 with an energy sufficient (/-24) to produce electrofission by the collisional mechanism represented by reaction (2). We also note that the bremsstrahlung produced collaterally by the fast electrons in the target material can also participat...

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“…11,12 Moreover, the generated laser pulses are to some extent a wavelength and duration tunable. 10,13 Such a laser is capable to amplify short pulses with a pulse duration down to a few tens of femtosecond.…”

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confidence: 99%

Resonant third harmonic generation of KrF laser in Ar gas

Rakowski

Barna

Suta

et al. 2014

Review of Scientific Instruments

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Electron energy deposition in an electron-beam pumped KrF amplifier: Impact of beam power and energy J. Appl. Phys. 91, 2662 (2002); 10.1063/1.1448409 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence. © 2014 AIP Publishing LLC. [http://dx

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Subpicosecond KrF* excimer-laser source

Cited by 120 publications

References 11 publications

Intensity-dependent loss properties of window materials at 248 nm

Intensity-dependent loss properties of window materials at 248 nm

Possibility of optically induced nuclear fission

Resonant third harmonic generation of KrF laser in Ar gas

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