Femtosecond laser direct writing of gratings and waveguides in high quantum efficiency erbium-doped Baccarat glass

Abstract

The femtosecond laser direct writing technique was employed to inscribe gratings and waveguides in high quantum efficiency erbium-doped Baccarat glass. Using the butt coupling technique, a systematic study of waveguide loss with respect to input pulse energy and writing speed was performed to achieve the best waveguide with low propagation loss (PL). By pumping at 980 nm, we observed signal enhancement in these active waveguides in the telecom spectral region. The refractive index change was smooth and we estimated it to be ∼10−3. The high quantum efficiency (∼80%) and a best PL of ∼0.9 dB cm−1 combined with signal enhancement makes Baccarat glass a potential candidate for application in photonics.