Ferroelectric gadolinium molybdate bistable light gate-memory cell

Claim 2

A bistable memory cell with electrical write-in and nondestructive optical readout comprising: a. a single crystal of the ferroelectric material gadolinium molybdate; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal, and the second polarizer in succession in a direction at an angle of approximately 6* to the crystallographic c axis in a plane parallel to the c axis and said plane being approximately 45* to the a and b axes; d. transparent electrodes on the said crystal for applying an electric field essentially along the c axis of the crystal; e. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween for inserting information into the memory device; f. the said crystal being oriented in a position relative to the directions of the said light polarizers for extinction when the electrical polarization is that corresponding to an applied electric pulse of a predetermined polarity; and g. means for sensing the light that has passed through the second polarizer.

Claim 3

An electrically controlled optical light gate-memory device comprising: a. a single ferroelectric crystal of a molybdate of a rare earth having two stable electrically, controlled states of spontaneous polarization and different optic axes positions for each state of spontaneous polarization; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal, and the second polarizer in succession; d. electrical means including transparent electrodes cooperating with the said crystal, for controlling the said state of the spontaneous polarization of the crystal; e. light-detecting means for sensing the light that has passed through the second polarizer; and f. the said crystal being oriented with respect to the said optic axes and the said light polarizers to provide a lower value of light to said light detector in one of the said stable states of polarization than in the other said stable state of polarization.

Claim 4

An electrically controlled optical light gate-memory device comprising: a. a single ferroelectric crystal of a molybdate of a rare earth having two stable electrically, controlled states of spontaneous polarization and different optic axes positions for each state of spontaneous polarization; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal, and the second polarizer in succession; d. electrical means including transparent electrodes cooperating with the said crystal, for controlling the said state of the spontaneous polarization of the crystal; e. light-detecting means for sensing the light that has passed through the second polarizer; and f. the said crystal being oriented with respect to the said optic axes and the said light polarizers to provide a lower value of light to said light detector in one of the said stable states of polarization than in the other said stable state of polarization.

Claim 5

A bistable memory cell and light gate having electrical write-in and nondestructive optical readout comprising: a. a crystal element cut from a single crystal of gadolinium molybdate, the element having two parallel crystal faces cut normal to a line making an angle of approximately 6* with the crystallographic c axis, said line lying in a plane containing the c axis and said plane being at approximately 45* to the crystallographic a and b axes; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal element, and the second polarizer in succession in a direction normal to the faces of the said crystal element for reading out the device; d. transparent electrodes on the said parallel faces of the crystal element for applying an electric field to the crystal element; e. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween for providing a uniform spontaneous polarization to the crystal element responsive to the polarity of the electric pulse for inserting information into the memory device; f. the said crystal element being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and g. detecting means for sensing the light that has passed through the second polarizer.

Claim 6

A bistable memory cell and light gate having electrical write-in and nondestructive optical readout comprising: a. a crystal element cut from a single crystal of gadolinium molybdate, the element having two parallel crystal faces cut normal to a line making an angle of approximately 6* with the crystallographic c axis, said line lying in a plane containing the c axis and said plane being at approximately 45* to the crystallographic a and b axes; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal element, and the second polarizer in succession in a direction normal to the faces of the said crystal element for reading out the device; d. transparent electrodes on the said parallel faces of the crystal element for applying an electric field to the crystal element; e. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween for providing a uniform spontaneous polarization to the crystal element responsive to the polarity of the electric pulse for inserting information into the memory device; f. the said crystal element being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and g. detecting means for sensing the light that has passed through the second polarizer.

Claim 7

The bistable memory cell and light gate as claimed in claim 3 wherein the thickness of the crystal element between the parallel cut crystal faces is determined by dividing a half wavelength of the reading-out light by the birefringence characteristic of the crystal material.

Claim 8

A bistable memory cell and light gate having electrical write-in and nondestructive optical readout comprising: a. a crystal element cut from a single crystal of gadolinium molybdate, the element being cut along the crystal axes and having parallel faces normal to the crystallographic c axis; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal element, and the second polarizer in succession in a direction making an angle of at least 6* with the crystallographic c axis of the crystal element; d. transparent electrodes on the said parallel faces of the crystal element for applying an electric field to the crystal element; e. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween for providing a uniform spontaneous polarization to the crystal element responsive to the polarity of the electric pulse for inserting information into the memory device; f. the said crystal element being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and g. detecting means for sensing the light that has passed through the second polarizer.

Claim 9

A bistable memory cell and light gate having electrical write-in and nondestructive optical readout comprising: a. a crystal element cut from a single crystal of gadolinium molybdate, the element being cut along the crystal axes and having parallel faces normal to the crystallographic c axis; b. first and second light polarizers having polarization directions at right angles; c. means for passing light through the first polarizer, the crystal element, and the second polarizer in succession in a direction making an angle of at least 6* with the crystallographic c axis of the crystal element; d. transparent electrodes on the said parallel faces of the crystal element for applying an electric field to the crystal element; e. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween for providing a uniform spontaneous polarization to the crystal element responsive to the polarity of the electric pulse for inserting information into the memory device; f. the said crystal element being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and g. detecting means for sensing the light that has passed through the second polarizer.

Claim 10

A logic array with electrical write-in and nondestructive optical readout providing a gate function with memory comprising: a. a plurality of equivalent single crystal elements cut from a crystal of the ferroelectric material gadolinium molybdate, each crystal element having two parallel crystal faces cut normal to a line making an angle of approximately 6* with the crystallographic c axis, said line lying in a plane containing the c axis and said plane being approximately 45* to the crystallographic a and b axes; b. positioning means for placing the plurality of crystal elements with their corresponding parallel faces in plane relationships, c. first and second light polarizers having polarization directions at right angles; d. means for passing light through the first polarizer, the plurality of crystal elements in plane relationship, and the second polarizer in succession in a direction normal to the faces of the said plurality of crystal elements for reading out the array; e. transparent electrodes on the said parallel faces of each of the said plurality of crystal elements for applying an electric field to each crystal element; f. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween independently to each crystal element for providing a uniform spontaneous polarization to each crystal element responsive to the polarity of the respective electric pulse for inserting information into each crystal of the logic array; g. each of the said crystal elements being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and h. detecting means for sensing the light that passes through the second polarizer.

Claim 11

A logic array with electrical write-in and nondestructive optical readout providing a gate function with memory comprising: a. a plurality of equivalent single crystal elements cut from a crystal of the ferroelectric material gadolinium molybdate, each crystal element having two parallel crystal faces cut normal to a line making an angle of approximately 6* with the crystallographic c axis, said line lying in a plane containing the c axis and said plane being approximately 45* to the crystallographic a and b axes; b. positioning means for placing the plurality of crystal elements with their corresponding parallel faces in plane relationships, c. first and second light polarizers having polarization directions at right angles; d. means for passing light through the first polarizer, the plurality of crystal elements in plane relationship, and the second polarizer in succession in a direction normal to the faces of the said plurality of crystal elements for reading out the array; e. transparent electrodes on the said parallel faces of each of the said plurality of crystal elements for applying an electric field to each crystal element; f. means coupled to the said electrodes for selectively applying an electric pulse of either polarity therebetween independently to each crystal element for providing a uniform spontaneous polarization to each crystal element responsive to the polarity of the respective electric pulse for inserting information into each crystal of the logic array; g. each of the said crystal elements being oriented in a position relative to the directions of the said light polarizers for extinction when the spontaneous polarization of the crystal element is that corresponding to an applied electric pulse of a predetermined polarity; and h. detecting means for sensing the light that passes through the second polarizer.