Formation mechanism of element distribution in glass under femtosecond laser irradiation

Abstract

We report on the formation mechanism of element distribution in glass under high-repetition-rate femtosecond laser irradiation. We simultaneously focused two beams of femtosecond laser pulses inside a glass and confirmed the formation of characteristically shaped element distributions. The results of the numerical simulation in which we considered concentration- and temperature-gradient-driven diffusions were in excellent qualitative agreement with the experimental results, indicating that the main driving force is the sharp temperature gradient. Since the composition of a glass affects its refractive index, absorption, and luminescence property, the results in this study provide a framework to fabricate a functional optical device such as optical circuits with a high-repetition-rate femtosecond laser.

Mechanisms of damage formation in glass in the process of femtosecond laser drilling

“…This result indicates that the damage formed around the entrance was caused by a factor different from the tensile stress generated by the stress wave. As the factor of damage which is not caused by tensile stress, modification by heat can be considered [23][24][25]. To investigate the effect of heat on the damage formation, we calculated the temperature distribution while the processing of laser drilling was ongoing, based on the calculation of the distributions of the laser intensity and the free-electron density inside glass.…”

Control of waveguide properties by tuning femtosecond laser induced compositional changes

“…13 More recently, element redistribution has been observed upon static 14,15 or dynamic 16,17 (moving sample) irradiation experiments mostly in silicate glasses. However, none of these works has provided evidence of local compositional changes leading to light guiding in the written structures.…”

“…Previous works have stressed the role of thermal gradients in fs laser-induced ion migration phenomena [14][15][16] or the opposite migration behavior of glass formers and modifiers. 12 Also more recently, thermal ionization has been analyzed as an important factor in high repetition rate processing of glass.…”

Soret coefficients of alkali oxides in alkali borate glass melts

“…The migration directions of glass components in binary-component glass melts were investigated by using a femtosecond laser to create a steep temperature gradient inside the glass. In CaOSiO 2 glass, the concentration of CaO was higher on the colder side; 10) in Na 2 OSiO 2 glass, the concentration of Na 2 O was higher on the colder side; 11) in Na 2 OB 2 O 3 glass, the concentration of Na 2 O was higher on the colder side; 12) and in Na 2 OGeO 2 glass, the concentration of Na 2 O was higher on the colder side. 13) However, this method does not provide the temperature distribution because the heated region is too small (<100¯m).…”