Spectral characterization of Yb–doped silica layers for high power laser applications

Abstract

Thick silica layers, doped with rare-earth elements are required as active media for high power waveguide lasers and amplifiers. In this work, Yb/Al-codoped silica particles were deposited on pure silica wafers, followed by high temperature sintering and post-sinter laser annealing treatment. The optical properties of the layers were monitored at different stages of the process using transmission spectrometry in the near IR to UV range, micro-Raman spectroscopy, fluorescence spectrum, and decay measurements. Evolution of the Yb3+ ion fluorescence and stabilization of the Si:O bonds as a result of the sintering process were observed.Measurements of 30μm thick layers showed high Yb absorption of 500dB/m at 980nm. The fluorescence lifetime was close to 1ms and the propagation loss was less than 20dB/m at 633nm, currently limited by the measurement system. The results show that a potential material for high power applications has been achieved.