Abstract

Recently, the interests in optical memory based on persistent spectral hole burning (PSHB) are increased because of its possibility of the application to high density optical memory. PSHB was observed for an organic dye doped in polymer and rear earth or transition metal doped in inorganic crystal or glasses up to now. Since PSHB was observed by two Russian groups (Gorokhovskii et al. and Kharlamov et al.) for free base phthalocyanine in a n-octane Shpol'skii matrix¹ and for perylene and 9-aminoacridine molecules in glassy ethanol matrix², PSHB materials are studied primarily for the polymer doped with an organic dye. But such materials can make hole only at very low temperature. Room temperature PSHB phenomena were observed on Sm²⁺ doped fluoride crystals³-⁵ and glasses⁶ recently, however these materials' Г_ih(inhomogeneous line width)/Г_h(homogeneous line width)'s which are the parameters of data multiplicity in PSHB optical memory are an order of unity. For the application of PSHB materials to optical memory, high operating temperature, high Г_ih/Г_h, and rapid reaction rate are wanted. Glass has a superiority on the view point of optical memory application because of its broad inhomogeneous line width and productivity. Our group has discovered room temperature PSHB for Sm²⁺ in borate glass systems whose Г_ih/Г_h is 24.⁷ PSHB for rear earth metal in glass matrix has not been studied seriously, yet. It is thought that the study of the relationship between the optical hole and glass structure is necessary.

© 1994 Optical Society of America