Transient spectral hole burning in erbium-doped fluoride glasses

We report what is, to the best of our knowledge, the first observation of transient spectral hole burning in erbium-doped fluorozirconate glass around 1.53 μm. Holes deeper than 12% were burnt. A study of the hole width as a function of power density, wavelength, temperature, and erbium concentration has been performed and underlines the role of spectral diffusion. Dynamics of refilling of the holes, involving optical pumping of the long-lived 4I13/2 excited state, was also investigated. The nearly linear temperature dependence of the hole width behaves as reported for other rare-earth ions and is interpreted within the framework of the two-level systems theory. Hole-refilling dynamics has been studied for three different erbium concentrations and is used to interpret the origin of the saturation.