Assessment of Rayleigh and non-Rayleigh Contributions to the Transmission Losses in fs-Laser Written Er/Yb-Codoped Phosphate Glass Waveguides

A detailed characterization procedure based on the numerical fit of a reduced number of measurements has been applied to two fs-laser written Er/Yb-codoped phosphate glass waveguides. One of them was written in a single scan writing process using higher peak power pulses, and the other one by using lower energy pulses and scanning the laser repetitively over the same region 20 times. The relative weight of non-Rayleigh transmission-loss mechanisms is analyzed for the different processing conditions. As a result of these measurements a quality parameter for fs-laser written active waveguides is proposed.