STP1141: Time Dependence of Laser-Induced Surface Breakdown in Fused Silica at 355 nm in the Nanosecond Regime

    Albagli, D
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Izatt, JA
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Hayes, GB
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Banish, B
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Janes, GS
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Itzkan, I
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Feld, M
    G.R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology, Cambridge, Massachusetts

    Pages: 8    Published: Jan 1991


    Abstract

    Laser-induced surface breakdown in fused silica has been studied as a function of pulse width in the nanosecond regime. The third harmonic of a Nd:YAG laser was used to produce 7.5 ns duration pulses (FWHM) at 355 nm. A novel system using optical delay lines was used to extend these pulses to variable widths between 7.5 and 400 ns. At each pulse width, the beam was focused onto the surface of a commercially available fused silica flat and the breakdown fluence was determined. The breakdown fluence threshold was found to scale as the pulse width to the 0.8 power, significantly higher than the 0.5 power reported elsewhere for similar cases. Experiments were also performed on 200 μm core fused silica optical fibers and the results obtained were consistent with a 0.8 power scaling law. This strong scaling law led to a dramatic increase in the amount of 355 nm light that could be transmitted through 200 μm core fibers — from 1–2 mJ at 7.5 ns up to over 30 mJ at 400 ns. An experiment was also performed to probe the recovery time of fused silica (the time separation between pulses such that their effects are independent). This time was determined to be less than 25 ns.


    Paper ID: STP23622S

    Committee/Subcommittee: F01.19

    DOI: 10.1520/STP23622S


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