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Polarization Coding of Photochemical Holes for Multilevel Logic Memory

IP.com Disclosure Number: IPCOM000051655D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Levenson, MD: AUTHOR

Abstract

Photochemical holes can be polarization coded to provide multilevel logic memory; i.e., different types of holes can be burned by polarizing the light. With some materials, for example, X-ray irradiated NzF, one can write one logic level with non-polarized light, a second logic level with light polarized along the 100 axis, and a third logic level with light polarized along the 010 axis.

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Polarization Coding of Photochemical Holes for Multilevel Logic Memory

Photochemical holes can be polarization coded to provide multilevel logic memory; i.e., different types of holes can be burned by polarizing the light. With some materials, for example, X-ray irradiated NzF, one can write one logic level with non-polarized light, a second logic level with light polarized along the 100 axis, and a third logic level with light polarized along the 010 axis.

The different logic levels are detected by measuring the change in the light intensity at a detector due to the interference of the light transmitted by the various types of holes with a polarized local oscillator wave that is incident on the detector whenever the memory is being interrogated. The local oscillator wave may be created by slightly rotating the polarization analyzer away from the orientation orthogonal to the interrogating probe beam. The probe beam in turn is polarized at 45 degrees to the pump beams used to write the information into the memory.

Some material systems can provide five or nine logic levels.

For example, with NaF and analogous material systems, a 110 or 110 oriented pump beam can induce the same king of anisotropies as a 100 or 010 oriented beam, but with axes rotated by 45 degrees, these holes can be detected. The 100 or 010 holes are then invisible.

Such a system yields a total of five logic levels as set forth below: 0 = No holes or (100 and 010 holes) or (110 and 110 holes) or...