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Browse Prior Art Database

Ferroelectric Solid Switchable Optical Waveguide

IP.com Disclosure Number: IPCOM000086547D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Hoechli, UT: AUTHOR

Abstract

The polarization of dielectric solids exhibiting incipient ferroelectricity (FE) at low temperatures can be changed locally by injection of defects.

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Ferroelectric Solid Switchable Optical Waveguide

The polarization of dielectric solids exhibiting incipient ferroelectricity (FE) at low temperatures can be changed locally by injection of defects.

Such critically polarizable substances like SrTiO(3) or KTaO(3) show no complete transition to the true ferroelectric state. However, upon cooling down near their ferroelectric transition temperature to e.g., 4 K, their dielectric constant increases to about 10/4/ indicating the beginning of ferroelectricity (incipient FE). Local polarization can be present in these substances at 4 K, even in the absence of true FE, that can be altered both reversibly and irreversibly by application of electric fields.

This phenomenon is used to build switchable optical waveguides in integrated optics. On a KTaO(3) wafer thin Au deposits 1 - 5 define an electrode pattern. Continually charged areas 1,2, and 3 build a bifurcated light path. A light beam which hits area 1 is deflected into areas 2 or 3 depending upon the state of switchable areas 4 and 5. Areas 4 and 5 can selectively be connected to a DC power supply.

The application of electric fields leads to uncompensated charges near the surface of the crystal. Ionic defects change the optical index such that total reflection occurs at the interface between stoichiometric and ion-deficient material.

Elongated zones with internal total reflection are used as optical waveguides on the wafer. They are formed in situ by applying fields t...