Er3+ doped waveguide amplifiers written with femtosecond laser in germanate glasses

► Active waveguides in GeO2-PbO-Ga2O3 glass doped with Er3+ by direct fs laser writing. ► Permanent refractive index change was obtained and estimated to be ∼6 × 10−3. ► The minimum propagation loss at 1532 nm was 4.8 dB/cm. ► Waveguides were formed under different laser pulse energies and scan velocities. ► Maximal internal gain of 2.7 dB/cm at 1.5 μm under 980 nm excitation was achieved.