Collection Of theses on high power laser and plasma physics, 2013, 11 (1): 1716, Published Online: Jun. 2, 2017
Role of thermal ionization in internal modification of bulk borosilicate glass with picosecond laser pulses at high repetition rates
Laser damage Laser damage Laser-induced breakdown Laser-induced breakdown Glass and other amorphous materials Glass and other amorphous materials Ultrafast lasers Ultrafast lasers Laser materials processing Laser materials processing Picosecond phenomena Picosecond phenomena
Abstract
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 teardropshaped inner structure is the damaged zone caused by high-density freeelectrons. 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.
Mingying Sun, Urs Eppelt, Wolfgang Schulz, Jianqiang Zhu. Role of thermal ionization in internal modification of bulk borosilicate glass with picosecond laser pulses at high repetition rates[J]. Collection Of theses on high power laser and plasma physics, 2013, 11(1): 1716.