High-temperature persistent spectral hole burning of Eu3+-doped SiO2 glass prepared by the sol-gel process

Persistent spectral hole burning was observed at temperatures higher than 77 K in SiO2 glass doped with the Eu3+ ions. The Eu3+-doped SiO2 glass was prepared using the sol-gel process of Si(OC2H5)4 and EuCl3⋅6H2O. A persistent spectral hole was burned in the excitation spectrum of the F07→5D0 transition of Eu3+ using a Rhodamine 6G dye laser, of which the hole width and depth were 1.6 cm−1 and ∼20% of the total intensity, respectively, at 77 K. Hole depth decreased with increasing temperature and disappeared above ∼130 K. A possible mechanism for the hole burning is related to the local structure around Eu3+ and the residual OH and H2O in the glass.