Femtosecond direct laser writing of an integrated gain medium in the near-IR range in a bismuth containing glass

We report on femtosecond direct laser writing (FDLW) of single-mode optical waveguide supported by bismuth photochemistry in a zinc phosphate glass. Propagation attenuation of 2 dB.cm −1 at 976 nm was measured. The waveguide was written twice with 16 laser passes separated by 250 nm to make a square-like structure of 6 µm × 6 µm to perform a single-mode waveguide at 976 nm. The refractive index contrast of the waveguide was estimated to 1.5 × 10 −3 by phase imaging microscopy. Hyper-spectral near-IR fluorescence confocal microscopy was performed to confirm the laser-induced valence change of Bi 3+ to Bi + ions, at the waveguide localization, demonstrating the FDLW creation of an integrated laser gain medium. Finally, a demonstration of waveguided laser amplification at 1345 nm is presented in this work.