Abstract: A light activated switching device is disclosed in which the receipt of a light signal is used to switch a light beam between two output ports. The input light beam is reflected from an interface between two regions having different indices of refraction when the light signal is present. The reflected light beam then exits through the first output port. In the absence of the light signal, the two regions have the same index of refraction, and the light beam passes through both regions and exits through the second output port.

Abstract: An improved non-volatile variable resistance element is disclosed. The resistive element is based on a semiconductor having a resistivity which is determined by the state of polarization of a ferroelectric layer.

Abstract: A method for selectively applying a voltage to selected points on a surface is disclosed. The method utilizes a layer of photo-conductive material in contact with the surface in question. The layer of photo-conductive material is illuminated in the region immediately above the selected points so as to cause the voltage on an electrode bonded to one surface of the photo-conductive region to be electrically connected to the selected points.

Abstract: An improved read/write optical disk is disclosed which is capable of being rewritten more than 10.sup.6 times. The disk utilizes a storage medium in which data is stored as different polarization states in the same phase of the material. The preferred embodiment utilizes a lead lanthanum zirconate titanate material for the storage medium. The state of polarization of the material at the location of a specified data bit is changed by applying a voltage to the bit location in question. The location is specified by illuminating the surface of the disk with light in the infra-red.