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Material for Photon-Gated Optical Holeburning Storage

IP.com Disclosure Number: IPCOM000060315D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Macfarlane, RM: AUTHOR [+3]

Abstract

Photon-gated materials form a broad class which provides suitable media for spectral holeburning storage. For this type of material, holeburning at an optical frequency 11 occurs only in the presence of a beam at a second frequency 12 . (The case 11 = 12 would result in holeburning which is non-linear in the laser power, and is included in this class.) These materials overcome an intrinsic limitation of single photon materials; viz after a certain number of read cycles, the absorption band is bleached by the reading beam due to the same mechanism used to write the holes into the band. In photon-gated materials, the bleaching can be turned on and off by irradiation with a second light beam. Reading is done with this gating beam turned off, and the information can be read without bleaching and associated loss of stored data.

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Material for Photon-Gated Optical Holeburning Storage

Photon-gated materials form a broad class which provides suitable media for spectral holeburning storage. For this type of material, holeburning at an optical frequency 11 occurs only in the presence of a beam at a second frequency 12 . (The case 11 = 12 would result in holeburning which is non-linear in the laser power, and is included in this class.) These materials overcome an intrinsic limitation of single photon materials; viz after a certain number of read cycles, the absorption band is bleached by the reading beam due to the same mechanism used to write the holes into the band. In photon-gated materials, the bleaching can be turned on and off by irradiation with a second light beam. Reading is done with this gating beam turned off, and the information can be read without bleaching and associated loss of stored data. A material which provides, for the first time, a medium with the capability of photon-gated operation in a holeburning information storage system is BaClF doped with 0.1 percent Sm2+. Holeburning occurs in the 20 GHz wide 7F0 T 5D0 line at 6879 A. Holes are burned by simultaneous irradiation with an information-carrying beam at 6879 A and a gating beam at 5145 A. The power density of both laser beams was N10 W/cm2, and exposure times of N 1 second gave N 10 percent deep holes. Holes burned in this way were very stable to reading by the red laser beam; in the absence of gating light, no hole was burned after 20 minutes of irradiation. Hole erasure occurs upon exposure to blue light, e.g., 4765 A from an Ar+ laser at power...