Gain determination of new erbium - bismuth doped germanium silicate optic glass for double-band optical amplification

This research focuses on the gain measurement and modeling of optical silica-germanium glass doped by erbium and bismuth activators to implement a two-band planar optical amplification. Using two activators, bismuth active centers with germanium (BAC-Ge) expand the amplification of the near-infrared bandwidth up to 1650 nm, where the optical attenuation of telecommunication fibers is less than 0.3 dB/km. We described the amplification mechanism based on the luminescence spectral response of the activators. We determined the differential amplification gain of the fabricated active glasses using a pulse measurement method and the calculation of the authentic model using waveguide propagation equations. A single source with a wavelength of 1480 nm was used for pumping in both optical bands. The emission and absorption cross-section coefficients were determined from the luminescence spectrum of the glasses by the Füchtbauer-Ladenburg equation with a Gaussian approximation and McCumber's theory. The calculated differential gain values are in good agreement with the measurement results. Our research leads to the conclusion that BAC-Ge optical activity is conditioned by the location of Bi atoms in the germano-silicate glass matrix with high GeO ₂ content.