Laser Amorphization of a Crystalline Phase in the Bulk of a Thermally Stable Lithium Aluminosilicate Glass-Ceramic

This paper presents results of femtosecond laser micromachining of a transparent glass-ceramic in the Li2O–Al2O3–SiO2 system with a near-zero linear thermal expansion coefficient in the thermal and athermal regimes. Electron microscopy and electron diffraction data confirm complete amorphization of nanocrystals of β-eucryptite-like solid solutions under the effect of laser pulses. Using quantitative phase microscopy, we have evaluated refractive index changes in individual laser-written tracks. In the athermal regime at a pulse repetition rate of 10 kHz, complete glass-ceramic amorphization leads to a decrease in the refractive index of the material (Δn = −0.0035) in the laser treatment region, which opens up the possibility of using direct laser writing of channel waveguides in a thermally stable glass-ceramic matrix.