II-VI compounds as a medium for optical data storage through fast persistent high density spectral holeburning

• Main Authors: HASAN ZAMEER UL, MATHUR VEERENDRA KUMAR
• Format: Patent
• Language: English
• Published: 04.03.2003
• Edition: 7
• Subjects: GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; INFORMATION STORAGE; PHYSICS; STATIC STORES; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS

High density, photon-gated persistent spectral holeburning is effectuated in rare earth doped II-VI compounds such as MgS, CaS, BaS and SrS. Two-photon ionization of rare earth ions is performed, selected by a narrow band laser, producing narrow regions of reduced absorption (optical holes) in the absorption spectrum of a rare earth ion. These holes are useful for such applications as high density memory (especially, high density re-writable or photo-erasable memory), spectral holographic memory, communication, etc., no and demonstrate great survivability over reading cycles, thermal cycles and elevated temperatures. The embedment of the rare earth doped II-VI compound in a matrix comprising a polymeric material (such as PMMA), prior to the effectuation of the holeburning, may be advantageous for many embodiments. Inventive practice has successfully burned two hundred forty photon gated spectral holes in the zero phonon line (ZPL) of the 4f-5d transition of Eu2+ in a magnesium sulfide host. CaS:Eu, CaS:Eu,Sm and MgS:Eu are among the materials which have demonstrated a very high density of spectral holes.