Browse Prior Art Database

Ferroelectric Optical Switch

IP.com Disclosure Number: IPCOM000094215D
Original Publication Date: 1966-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Smith, AW: AUTHOR

Abstract

Ferroelectric crystals are characterized by large optical birefringences which appear spontaneously on passing below the Curie temperature Tc. In crystals which are piezoelectric above Tc, such as potassium dihydrogen phosphate KDP and Rochelle Salts RS, the sign of the birefringence depends on the direction of the polarization along the ferroelectric axis. Thus, a beam of polarized light can be used to sense the direction of polarization in a crystal. If the hysteresis loop of the crystal is reasonably square, the latter forms a bistable element that can switch a beam of light on or off by electrical pulses applied to conductors associated with such bistable element. The bistable element remains either in its transmitting or nontransmitting state depending upon the application of proper polarity pulses to the conductors.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 63% of the total text.

Page 1 of 2

Ferroelectric Optical Switch

Ferroelectric crystals are characterized by large optical birefringences which appear spontaneously on passing below the Curie temperature Tc. In crystals which are piezoelectric above Tc, such as potassium dihydrogen phosphate KDP and Rochelle Salts RS, the sign of the birefringence depends on the direction of the polarization along the ferroelectric axis. Thus, a beam of polarized light can be used to sense the direction of polarization in a crystal. If the hysteresis loop of the crystal is reasonably square, the latter forms a bistable element that can switch a beam of light on or off by electrical pulses applied to conductors associated with such bistable element. The bistable element remains either in its transmitting or nontransmitting state depending upon the application of proper polarity pulses to the conductors.

A representative use of the optical switch is in a two-dimensional memory array as shown. The individual switching units 2 are ferro-electric crystals. Each row of crystals is associated with a transparent horizontal electrode 4, 4', etc. Each column of crystals is associated with a vertical transparent electrode 6, 6', etc. The array of crystals is illuminated from one side with a collimated, linearly polarized beam 8 from a laser source not shown. In the case of RS, sheet polarizer 10 is placed on the side of the array opposite to the side at which the laser beam enters. Where KDP is used, an additional birefringen...