Femtosecond laser induced PL change in Sm-doped sodium borate glass and 3D optical memory

We report on a femtosecond laser-induced photoluminescence (PL) change in Sm-doped sodium-borate glass and its potential application to three-dimensional optical memory. Irradiation with a femtosecond pulsed laser (800 nm, 1 kHz, 100 fs) induced a new PL peak near 682 nm, resulting from the photoreduction of Sm ions from Sm3+ to Sm2+. This makes it possible to readout the stored data by detecting the new PL peak as a signal. Multilayer patterns of various dot sizes and interlayer spacings were fabricated by femtosecond pulsed laser. These patterns were read out by a fluorescent confocal microscope which detected the emission at 682 nm as a signal. Here we discuss the feasibility of 3D optical memory by use of PL change in Sm-doped sodium borate glass.