<title>Room-temperature persistent spectral hole burning of rare-earth-ion-doped glasses prepared by sol-gel process</title>

Abstract

ABSTRACT Room tempemture peisistent spectnil hole burning PSHB) was observed in Sm2 and Eu3tdoped Al2O-SiO2 glassesprepared by a sol-gel method. The glasses were obtained by heating the gels in hydrogen gas and the spectral hole wasburned in the excitation spectnim of the 7F0—D0 transition of the Sm2 and Eu3 ions. The depth of the hole burned at 77K decreased with incieasing the cycling tempeiature. The deciease in the hole-depth is due to the thennal ielaxation of theburnt-state of OH bonds sunounding the rare-earth ions. The depth of hole burned in the Sm2-doped glass was independentof temperatuie zanging fmm 200 to 300 K and decreased above 300 K. The Eu-doped glass heated in 2O%H2-8O%N2 gasexhibited the PSHB at mom tempeiature. We considered that the electmn tninsfer between the nre-easth ions and the Al-related defect centers acts for hole burning. 1. INTRODUCTION Since a persistent spectral hole burning (PSHB) phenomenon was first obseived at room temperatui in Sm2tdopedBaFCl0.Br0.5 clystal,' many studies have been carried out to develop the Sm2-doped materials. The room-temperaturePSHB is a significant scientific breakthrough because of its potential use in high-density frequency-domain optical storage.Glasses doped with Sm2-ions, in particular, are considered to be more favorable than ciystals for practical devices becauseof their wide inhomogeneous line width, compositional variety and easy mass pmduction. So far, conventional glass