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IMPLEMENTATION of DIGITAL OPTICAL LOGIC USING PHOTON-GATED SPECTRAL HOLE-BURNING

IP.com Disclosure Number: IPCOM000039640D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 4 page(s) / 29K

Publishing Venue

IBM

Related People

Moerner, WE: AUTHOR

Abstract

Implementation of digital optical logic functions is described in which photon-gated persistent spectral hole-burning (PHB) is used. As is well known in the art, any general logic function can be synthesized using a combination of NOR (or NAND) gates, so a specific implementation of an optical NOR gate with optical latch and storage is described. (Image Omitted) The logic operation is implemented by altering the transmission of a material in which spectral holes can be burned, such as divalent samarium ions in BaClF or carbazole molecules in boric acid glass, for example. Without loss of generality, assume that the site-selection within the inhomogeneous absorption profile is performed with a red laser beam, and that the gating function is performed with a green beam.

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IMPLEMENTATION of DIGITAL OPTICAL LOGIC USING PHOTON-GATED SPECTRAL HOLE-BURNING

Implementation of digital optical logic functions is described in which photon- gated persistent spectral hole-burning (PHB) is used. As is well known in the art, any general logic function can be synthesized using a combination of NOR (or NAND) gates, so a specific implementation of an optical NOR gate with optical latch and storage is described.

(Image Omitted)

The logic operation is implemented by altering the transmission of a material in which spectral holes can be burned, such as divalent samarium ions in BaClF or carbazole molecules in boric acid glass, for example. Without loss of generality, assume that the site-selection within the inhomogeneous absorption profile is performed with a red laser beam, and that the gating function is performed with a green beam. By changing the optical frequency of the red beam, multiple logic operations can be performed, as described below. Consider one 'pixel', i.e., one region of material that can be simultaneously irradiated with both beams. A single pixel acts as a logical AND gate with latching and storage in the following fashion. Assume that no hole has been written in the pixel at a fixed red beam wavelength.

See Fig. 1 and the accompanying truth table. Assume that each beam is controlled by a clocking shutter which is normally closed. The shutter can be any suitable sort of light valve, such as a liquid crystal, acousto-optic shutter, etc. A logical '1' for the red beam 1 means that the red beam 1 is present at the clocking shutter 2 (high intensity). A logical "O" is defined by the absence of intensity in the red beam. The state of the red beam thus defines a logical Boolean variable R. Similar definitions apply for the green beam 3, the state of which defines the value of a Boolean variable G. The logical operation consists of opening the clocking shutters 2, 4 for the two beams 1, 3 to produce values for the input variables R and G at the material 5. After a length of time defined by the material 5 and the beam 1, 3 intensities, the clocking shutters 2, 4 are closed.

The output of the logical operation, Q, consists of subsequently measuring the transmission of the pixel at the red wavelength with a red probe beam 6 as shown after the completion of the irradiation with the input variables. Q is defined to be a logical '1' if the transmission of the pixel is high (which would be the case if a hole were burned), and a logical "0" if the transmission is low (no hole burned). IMPLEMENTATION OF DIGITAL OPTICAL LOGIC USING PHOTON-GATED SPECTRAL HOLE-BURNING - Continued Now, since the material has been chosen to be a photon-gated hole burning material, no hole is burned unless both the red and the green beams are present simultaneously (R=1 and G=1). Thus, a single pixel performs the logical AND function, and the output variable Q will be a '1' if and only if both R and G are logical '1's. In addition, we...