Structural changes in fused silica after exposure to focused femtosecond laser pulses

Abstract

Using in situ Raman scattering in a confocal microscopy setup, we have observed changes in the network structure of fused silica after modifying regions inside the glass with tightly focused 800-nm 130-fs laser pulses at fluences of 5-200 J cm(-2). The Raman spectra show a large increase in the peaks at 490 and 605cm(-1), owing to 4- and 3-membered ring structures in the silica network, indicating that densification occurs after exposure to the femtosecond laser pulses. The results are consistent with the formation of a localized plasma by the laser pulse and a subsequent microexplosion inside the glass.

Tomographic measurement of femtosecond-laser induced stress changes in optical fibers

“…Raman data indicate an increase in the number of four-and three-membered ring structures for fused silica, which is associated with a densification of the glass after exposure to the femtosecond irradiation. 8 For germanosilicate fibers, it has already been pointed out earlier 9 that UV irradiation changes the Raman spectra of the fiber, indicating a densification of the doped core region. In the case of germanosilicate fibers, the densification is accompanied by a modification of the fiber residual stress profile.…”

Size dependence of elastic mechanical properties of nanocrystalline aluminum

“…20,21 Most interestingly, the changes revealed by the ring size distribution are known to characterize the "medium-range order" nature of amorphous materials. 22,23 Independent experiments on compressed bulk silica glass 24,25 have shown an enhancement of Raman lines associated with a)…”

Optically Produced Arrays of Planar Nanostructures inside Fused Silica

“…The very existence of nanoplanes that develop over thousands of laser shots requires that there is a memory in the material that can feed back to the breakdown. Such a memory could arise from metastable color centers [10] or permanent changes in electronic structure associated with chemical reorganization [11]. Either of these processes could seed localized ionization around areas that have already been modified.…”