Abstract

A newly designed optical aluminosilicate glass that supports femotsecond laser written ultra-low loss optical waveguides is presented in this paper. Propagation losses as low as −0.020 ± 0.003 and −0.037 ± 0.003 dB cm−1 at 1310 and 1550 nm, respectively, are enabled by engineering the glass composition. Raman, Brillouin and electron microscopies are used to understand the origins of femtosecond laser-induced refractive index changes.