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Title: Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals

Abstract

The damage in fused silica and CaF{sub 2} crystals induced by wavelength tunable femtosecond lasers is studied. The threshold fluence is observed to increase rapidly with laser wavelength {lambda} in the region of 250-800 nm, while it is nearly a constant for 800<{lambda}<2000 nm. The ultrafast electronic excitation is also studied by a pump and probe method. The reflectivity increases rapidly in the latter half of pump pulse, which supports that impact ionization plays an important role in the generation of conduction band electrons (CBEs). We study the CBEs absorption via subconduction-band (sub-CB) transition, and develop a coupled avalanche model. Our results indicate that the CBEs absorption via sub-CB transition plays an important role in the damage in dielectrics irradiated by the visible and near ultraviolet femtosecond lasers. Our theory explains well the experiments.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;  [1];  [2];  [2];  [2];  [3]
  1. Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
  2. (China)
  3. (Japan)
Publication Date:
OSTI Identifier:
20787904
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 73; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevB.73.054105; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; CALCIUM FLUORIDES; CRYSTALS; DIELECTRIC MATERIALS; ELECTRONS; EXCITATION; EXCITED STATES; IONIZATION; IRRADIATION; LASERS; OPTICAL PUMPING; PULSES; REFLECTIVITY; SILICA; SILICON COMPOUNDS; ULTRAVIOLET RADIATION; WAVELENGTHS

Citation Formats

Jia, T. Q., Chen, H. X., Huang, M., Zhao, F. L., Li, X. X., Xu, S. Z., Sun, H. Y., Feng, D. H., Li, C. B., Wang, X. F., Li, R. X., Xu, Z. Z., He, X. K., Kuroda, H., and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou, 510275, State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, and Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581. Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals. United States: N. p., 2006. Web. doi:10.1103/PHYSREVB.73.0.
Jia, T. Q., Chen, H. X., Huang, M., Zhao, F. L., Li, X. X., Xu, S. Z., Sun, H. Y., Feng, D. H., Li, C. B., Wang, X. F., Li, R. X., Xu, Z. Z., He, X. K., Kuroda, H., and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou, 510275, State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, & Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581. Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals. United States. doi:10.1103/PHYSREVB.73.0.
Jia, T. Q., Chen, H. X., Huang, M., Zhao, F. L., Li, X. X., Xu, S. Z., Sun, H. Y., Feng, D. H., Li, C. B., Wang, X. F., Li, R. X., Xu, Z. Z., He, X. K., Kuroda, H., and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou, 510275, State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, and Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581. Wed . "Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals". United States. doi:10.1103/PHYSREVB.73.0.
@article{osti_20787904,
title = {Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals},
author = {Jia, T. Q. and Chen, H. X. and Huang, M. and Zhao, F. L. and Li, X. X. and Xu, S. Z. and Sun, H. Y. and Feng, D. H. and Li, C. B. and Wang, X. F. and Li, R. X. and Xu, Z. Z. and He, X. K. and Kuroda, H. and and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai and State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou, 510275 and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai and Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581},
abstractNote = {The damage in fused silica and CaF{sub 2} crystals induced by wavelength tunable femtosecond lasers is studied. The threshold fluence is observed to increase rapidly with laser wavelength {lambda} in the region of 250-800 nm, while it is nearly a constant for 800<{lambda}<2000 nm. The ultrafast electronic excitation is also studied by a pump and probe method. The reflectivity increases rapidly in the latter half of pump pulse, which supports that impact ionization plays an important role in the generation of conduction band electrons (CBEs). We study the CBEs absorption via subconduction-band (sub-CB) transition, and develop a coupled avalanche model. Our results indicate that the CBEs absorption via sub-CB transition plays an important role in the damage in dielectrics irradiated by the visible and near ultraviolet femtosecond lasers. Our theory explains well the experiments.},
doi = {10.1103/PHYSREVB.73.0},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 5,
volume = 73,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}
  • The depth distribution of ultraviolet laser irradiation-induced defects in fused silica has been determined using cathodoluminescence (CL) microanalysis. CL emissions have been observed at 1.9, 2.2, 2.7, and 4.4 eV. In addition, following a CO{sub 2} laser treatment for damage mitigation, an emission at 3.2 eV is also observed. The CL emissions have been identified with the nonbridging oxygen hole center, the self-trapped exciton, the oxygen-deficient center, and the aluminum impurity center. The spatially resolved CL data are consistent with the damage initiation at the exit surface. The concentration of 355-nm laser-induced defects is greatest at the surface and monotonicallymore » decays to preirradiation levels at {approx}10-{mu}m depth below the surface. The CO{sub 2} processing reduces the defect concentration and spatial distribution to a maximum depth of {approx}6 {mu}m, confirming significant damage mitigation.« less
  • We investigate the effect of different heat treatments on the laser-induced damage probabilities of fused silica samples. Isothermal annealing in a furnace is applied, with different temperatures in the range 700–1100 °C and 12 h annealing time, to super-polished fused silica samples. The surface flatness and laser damage probabilities at 3 ns, 351 nm are measured before and after the different annealing procedures. We have found a significant improvement of the initial laser damage probabilities of the silica surface after annealing at 1050 °C for 12 h. A similar study has been conducted on CO{sub 2} laser-processed sites on the surface of the samples. Before andmore » after annealing, we have studied the morphology of the sites, the evolution of residual stress, and the laser-induced damage threshold measured at 351 nm, 3 ns. In this case, we observe that the laser damage resistance of the laser created craters can reach the damage level of the bare fused silica surface after the annealing process, with a complete stress relieve. The obtained results are then compared to the case of local annealing process by CO{sub 2} laser irradiation during 1 s, and we found similar improvements in both cases. The different results obtained in the study are compared to numerical simulations made with a thermo-mechanical model based on finite-element method that allows the simulation of the isothermal or the local annealing process, the evolution of stress and fictive temperature. The simulation results were found to be very consistent with experimental observations for the stresses evolution after annealing and estimation of the heat affected area during laser-processing based on the density dependence with fictive temperature. Following this work, the temperature for local annealing should reach 1330–1470 °C for an optimized reduction of damage probability and be below the threshold for material removal, whereas furnace annealing should be kept below the annealing point to avoid sample deformation.« less
  • We investigate experimentally and numerically the damage tracks induced by tightly focused (NA=0.5) infrared femtosecond laser pulses in the bulk of a fused silica sample. Two types of irreversible damage are observed. The first damage corresponds to a permanent change of refractive index without structural modifications (type I). It appears for input pulse energies beyond 0.1 {mu}J. It takes the form of a narrow track extending over more than 100 {mu}m at higher input powers. It is attributed to a change of the polarizability of the medium, following a filamentary propagation which generates an electron-hole plasma through optical field ionization.more » A second type of damage occurs for input pulse energies beyond 0.3 {mu}J (type II). It takes the form of a pear-shaped structural damage associated with an electron-ion plasma triggered by avalanche. The temporal evolution of plasma absorption is studied by pump-probe experiments. For type I damage, a fast electron-hole recombination is observed. Type II damage is linked with a longer absorption.« less
  • We report the self-formation of quasiperiodic void structure with the length of several hundred micrometers inside the CaF{sub 2} crystal. The quasiperiodical voids along the propagation direction of the laser beam were formed spontaneously after the irradiation of a single femtosecond laser beam which was focused at a fixed point inside the crystal sample. The length of the void array varied with the focal depth beneath the sample surface. The possible mechanism of the self-formed void structure was discussed.
  • In a fully coupled thermomechanical model of the nanoscale deformation in amorphous SiO 2 due to laser heating is presented. Direct measurement of the transient, nonuniform temperature profiles was used to first validate a nonlinear thermal transport model. Densification due to structural relaxation above the glass transition point was modeled using the Tool-Narayanaswamy (TN) formulation for the evolution of structural relaxation times and fictive temperature. TN relaxation parameters were derived from spatially resolved confocal Raman scattering measurements of Si–O–Si stretching mode frequencies. These thermal and microstructural data were used to simulate fictive temperatures which are shown to scale nearly linearlymore » with density, consistent with previous measurements from Shelby et al. Volumetric relaxation coupled with thermal expansion occurring in the liquid-like and solid-like glassy states lead to residual stresses and permanent deformation which could be quantified. But, experimental surface deformation profiles between 1700 and 2000 K could only be reconciled with our simulation by assuming a roughly 2 × larger liquid thermal expansion for a-SiO 2 with a temperature of maximum density ~150 K higher than previously estimated by Bruckner et al. Calculated stress fields agreed well with recent laser-induced critical fracture measurements, demonstrating accurate material response prediction under processing conditions of practical interest.« less