Femtosecond laser-matter interactions in ternary zinc phosphate glasses

Abstract

We investigate the interaction of ultrashort laser pulses with ternary zinc phosphate glasses. We explore the viability of ten different glass compositions with different levels of alumina to inscribe optical waveguides via the fs-laser direct writing technique, finding that only samples with [O]/[P] ratios of 3.25 are suitable candidates. We also test a zinc magnesium phosphate glass to fabricate waveguide Bragg gratings in order to generate filters and mirrors with specific spectral properties. Confocal Raman spectroscopy inspection shows that laser-damaged material exhibits a relative intensity decrease and a subtle blue-shift on the 1209 cm-1 Raman peak, which implies a relative reduction on the content of Q(2) tetrahedra species within the glass network thus suggesting a laser-induced depolymerization. In contrast, optical waveguides and smooth laser-induced changes do not exhibit such noticeable structural modifications.