Open AccessRole of thermal ionization in internal modification of bulk borosilicate glass with picosecond laser pulses at high repetition rates
Author(s) -
Mingying Sun,
Urs Eppelt,
Wolfgang Schulz,
Jianqiang Zhu
Publication year - 2013
Publication title -
optical materials express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 66
ISSN - 2159-3930
DOI - 10.1364/ome.3.001716
Subject(s) - borosilicate glass , materials science , picosecond , laser , ionization , thermal , repetition (rhetorical device) , optoelectronics , optics , composite material , ion , physics , quantum mechanics , meteorology , linguistics , philosophy
We study the roles of thermal ionization and electronic damage in the internal modification of bulk borosilicate glass by high repetition rate picosecond laser pulses. Laser-induced plasma generation, nonlinear energy deposition and steady temperature distribution are numerically analyzed. The simulated modified regions show good agreement with the experimental results, thereby revealing the roles of thermal damage and electronic damage in the internal modification. While the elliptical outer structure is recognized as the molten region, we found that the teardrop-shaped inner structure is the damaged zone caused by high-density free-electrons. In the formation of the inner structure, cascade ionization is seeded by thermal ionization instead of multi-photon ionization and dramatically increases the free-electron density to the damage threshold. The contour of the inner structure is found to be corresponding to a characteristic isotherm of around 3000 ~4000 °C