US5206829A
Expired / Lapsed
US
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Thin film ferroelectric electro-optic memory
Assignee: California Institute of Technology
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Filing: 1990-10-24
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Granted: 1993-04-27
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Expires: 2010-10-24
Abstract
Abstract An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.
Inventors
- 👤 Sarita Thakoor
- 👤 Anilkumar P. Thakoor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:25
CPC Classifications
H; H10; H10B; H10B53/00; G; G06; G06E; G06E3/00; G06E3/001; G06E3/005; G06N; G06N3/00; G06N3/02; G06N3/06; G06N3/067; G06N3/0675; G11; G11C; G11C11/00; G11C11/21; G11C11/22; G11C11/56; G11C11/5657; G11C27/00; G11C7/00; G11C7/005
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
90 words
A data cell comprising: a transparent top electrode; a bottom electrode; a thin film of ferroelectric material therebetween; means for applying a level of remanent polarization to the thin film of ferroelectric material, said level being related to an analog value to be stored; and means for applying light to said thin film, said light having a wavelength near the bandgap of the ferroelectric material, said light being applied to generate a photoresponse therein a magnitude of which is related to the product of said analog value and said intensity.
Claim 2
Dependent Claim
90 words
A data cell comprising: a transparent top electrode; a bottom electrode; a thin film of ferroelectric material therebetween; means for applying a level of remanent polarization to the thin film of ferroelectric material, said level being related to an analog value to be stored; and means for applying light to said thin film, said light having a wavelength near the bandgap of the ferroelectric material, said light being applied to generate a photoresponse therein a magnitude of which is related to the product of said analog value and said intensity.
Claim 3
Dependent Claim
13 words
The data cell claimed in claim 1, wherein the ferroelectric material is PZT.
Claim 4
Dependent Claim
25 words
The data cell claimed in claim 1, wherein the film of ferroelectric material is in the range of about 0.05 μm to 1 μm thick.
Claim 5
Dependent Claim
24 words
The data cell claimed in claim 1, wherein the wavelength of the applied light is in the range of about 350 to 450 nm.
Claim 6
Dependent Claim
25 words
The data cell claimed in claim 1, wherein the intensity of the applied light is in the range of 1 to 100 mW/cm 2 .
Claim 7
Independent Claim
64 words
A method for storing and retrieving data, comprising the steps of: polarizing a thin film of ferroelectric material to obtain a level of remanent polarization therein related to an analog value to be stored; and applying light to said thin film, said light having a wavelength near the bandgap of the ferroelectric material, said light generating a photoresponse therein related to said analog value.
Claim 8
Independent Claim
64 words
A method for storing and retrieving data, comprising the steps of: polarizing a thin film of ferroelectric material to obtain a level of remanent polarization therein related to an analog value to be stored; and applying light to said thin film, said light having a wavelength near the bandgap of the ferroelectric material, said light generating a photoresponse therein related to said analog value.
Claim 9
Dependent Claim
17 words
The method for storing and retrieving data claimed in claim 6, wherein the ferroelectric material is PZT.
Claim 10
Dependent Claim
29 words
The method for storing and retrieving data claimed in claim 6, wherein the film of ferroelectric material is in the range of about 0.05 μm to 1 μm thick.
Claim 11
Dependent Claim
28 words
The method for storing and retrieving data claimed in claim 6, wherein the wavelength of the applied light is in the range of about 350 to 450 nm.
Claim 12
Dependent Claim
29 words
The method for storing and retrieving data claimed in claim 6, wherein the intensity of the applied light is in the range of 1 to 100 mW/cm 2 .
Claim 13
Independent Claim
78 words
A method for computing the product of stored data and incident data, comprising the steps of: applying an electrical signal to store analog data in a photoresponsive, polarizable material by polarizing the material to a level of remanent polarization related to an analog value; and then applying an intensity modulated optical signal incident to the material to generate a photoresponse therein, a magnitude of said photoresponse being related to the product of said intensity and said analog value.
Claim 14
Independent Claim
78 words
A method for computing the product of stored data and incident data, comprising the steps of: applying an electrical signal to store analog data in a photoresponsive, polarizable material by polarizing the material to a level of remanent polarization related to an analog value; and then applying an intensity modulated optical signal incident to the material to generate a photoresponse therein, a magnitude of said photoresponse being related to the product of said intensity and said analog value.
Claim 15
Dependent Claim
10 words
The method of claim 11, wherein the material is ferroelectric.
Claim 16
Dependent Claim
32 words
The method of claim 12 wherein the material is in the form of a thin film and the wavelength of the incident optical signal is near the bandgap of the ferroelectric material.
Claim 17
Dependent Claim
11 words
The method of claim 13 wherein the ferroelectric material is PZT.
Claim 18
Dependent Claim
20 words
The method of claim 14, wherein the film is in the range of about 0.05 μm to 1 μm thick.
Claim 19
Dependent Claim
22 words
The method of claim 14, wherein the wavelength of the applied light is in the range of about 350 to 450 nm.
Claim 20
Dependent Claim
23 words
The method of claim 14, wherein the intensity of the applied light is in the range of 1 to 100 mW/cm 2 .
References Cited (Backward Citations)
US3855004A
Cited
US4051465A
Cited
US4101975A
Cited
US4103341A
Cited
US4139908A
Cited
US4144591A
Cited
US4126901A
Cited
US4247914A
Cited
US4250567A
Cited
US4524294A
Cited
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