Valence manipulation by lasers of samarium ion in micrometer-scale dimensions inside transparent glass

We report the first valence manipulation of a rare-earth ion, samarium, in a transparent glass by an infrared femtosecond laser and a 4-dicyanmethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) dye laser. Absorption and photoluminescence spectra showed that some of the Sm3+ ions in the focus of the laser beam within the glass sample were reduced to Sm2+ ions after femtosecond laser irradiation. The laser-reduced part was further irradiated by the DCM dye laser at 680 nm. Persistent spectral hole burning was observed at 680 nm in the excitation spectrum. The observed phenomenon could be useful in the fabrication of optical memory devices that can store data in both space and wavelength axes as well as micro-optical devices.