US3679985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic wave parametric amplifier/converter
Assignee: International Business Machines Corp
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Filing: 1970-06-30
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Granted: 1972-07-25
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Expires: 1990-06-30
Abstract
Abstract A parametric device for acoustic waves which does not depend on the non-linearities of a medium for operation. Both degenerate and non-degenerate parametric amplifier/converters are provided in which first order velocity changes give parametric interactions. The electric field associated with an acoustic wave in a piezolectric medium is modulated by an electric pump wave. This is accomplished by modulating the conductivity of a region in the piezoelectric medium, or close to that medium. The resulting modulation of the K-vector of the acoustic wave leads to parametric interactions between the acoustic signal wave, the electric pump wave, and the generated idler wave. Various effects, such as the field effect and the photoconductive effect, are used to modulate the conductivity of the region.
Inventors
- 👤 Frank F Fang
- 👤 Eric G Lean
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 02:54
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/19; G06G7/195; H; H01; H01F; H01F13/00; H03; H03F; H03F13/00; H03F7/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
177 words
A parametric device for acoustic signal waves, comprising: a piezoelectric medium capable of supporting a surface acoustic signal wave; means for introducing said surface acoustic wave into said piezoelectric medium; means for generating an electric pump wave which parametrically interacts with said surface waves in said medium, said electric pump wave having a frequency omega p related to the signal wave frequency omega s by the expression omega p omega s + omega i, where omega i is the frequency of an idler wave supportable in said piezoelectric medium, said parametric interaction satisfying conservation of energy and momentum in said piezoelectric medium, wherein said means for generating said electric pump wave is comprised of a region of variable conductivity in close proximity to said piezoelectric medium which is responsive to a means for changing said conductivity periodically, said electric pump wave having a frequency twice that of said signal wave and being phase matched to said signal wave in said medium, means for detecting said surface acoustic wave after said parametric interaction with said electric pump wave.
Claim 2
Dependent Claim
177 words
A parametric device for acoustic signal waves, comprising: a piezoelectric medium capable of supporting a surface acoustic signal wave; means for introducing said surface acoustic wave into said piezoelectric medium; means for generating an electric pump wave which parametrically interacts with said surface waves in said medium, said electric pump wave having a frequency omega p related to the signal wave frequency omega s by the expression omega p omega s + omega i, where omega i is the frequency of an idler wave supportable in said piezoelectric medium, said parametric interaction satisfying conservation of energy and momentum in said piezoelectric medium, wherein said means for generating said electric pump wave is comprised of a region of variable conductivity in close proximity to said piezoelectric medium which is responsive to a means for changing said conductivity periodically, said electric pump wave having a frequency twice that of said signal wave and being phase matched to said signal wave in said medium, means for detecting said surface acoustic wave after said parametric interaction with said electric pump wave.
Claim 3
Dependent Claim
24 words
The device of claim 1, wherein said region comprises a surface inversion layer whose electrical conductivity is periodically varied by said conductivity changing means.
Claim 4
Dependent Claim
49 words
The device of claim 1, wherein said region comprises a semiconductor layer adjacent said piezoelectric medium, said semiconductor layer having an inversion layer in contact with said piezoelectric medium wherein said semiconductor layer is electrically connected to an electrical source for periodically varying the conductivity of said semiconductor layer.
Claim 5
Dependent Claim
33 words
The device of claim 1 where said region comprises a photoconductive layer adjacent said piezoelectric medium, and said conductivity changing means is a radiation source whose output is directed onto said photoconductive layer.
Claim 6
Dependent Claim
157 words
A parametric device for surface acoustic waves, comprising: a piezoelectric medium capable of supporting said surface acoustic waves; means for introducing said surface acoustic waves into said piezoelectric medium; means for generating an electric pump wave which parametrically interacts with said surface waves in said medium, said electric pump wave having a frequency omega p related to the signal wave frequency omega s by the expression omega p omega s + omega i, where omega i is the frequency of an idler wave supportable in said piezoelectrIc medium, said parametric interaction satisfying conservation of energy and momentum in said piezoelectric medium, wherein said means for generating said electric pump wave is comprised of a region of variable conductivity responsive to a means for changing said conductivity periodically, said region including free electrical carrier sources having a spatial periodicity l related to the wave vector kp of said electric pump wave by the relation kp 2 pi /1.
Claim 7
Dependent Claim
157 words
A parametric device for surface acoustic waves, comprising: a piezoelectric medium capable of supporting said surface acoustic waves; means for introducing said surface acoustic waves into said piezoelectric medium; means for generating an electric pump wave which parametrically interacts with said surface waves in said medium, said electric pump wave having a frequency omega p related to the signal wave frequency omega s by the expression omega p omega s + omega i, where omega i is the frequency of an idler wave supportable in said piezoelectrIc medium, said parametric interaction satisfying conservation of energy and momentum in said piezoelectric medium, wherein said means for generating said electric pump wave is comprised of a region of variable conductivity responsive to a means for changing said conductivity periodically, said region including free electrical carrier sources having a spatial periodicity l related to the wave vector kp of said electric pump wave by the relation kp 2 pi /1.
Claim 8
Dependent Claim
24 words
The device of claim 5, wherein said region comprises a surface inversion layer whose electrical conductivity is periodically varied by said conductivity changing means.
Claim 9
Dependent Claim
49 words
The device of claim 5, wherein said region comprises a semiconductor layer adjacent said piezoelectric medium, said semiconductor layer having an inversion layer in contact with said piezoelectric medium wherein said semiconductor layer is electrically connected to an electrical source for periodically varying the conductivity of said semiconductor layer.
Claim 10
Dependent Claim
43 words
The device of claim 5, where said region is a portion of said piezoelectric medium, and said means for changing said conductivity is an electrical source insulated from said region by a thin insulating region located between said electrical source and said region.
Claim 11
Dependent Claim
46 words
The device of claim 5, wherein said region of variable conductivity is a photoconductive material located adjacent said one surface of said medium, and said means for periodically varying the conductivity of said photoconductive layer is a radiation source whose output impinges upon said photoconductive layer.
Claim 12
Dependent Claim
42 words
The device of claim 9, wherein said photoconductive material is arranged in discrete regions adjacent said one surface, said regions having a periodic spacing l related to the wave vector kp of the pump wave by the relations kp 2 pi /1.
Claim 13
Dependent Claim
48 words
The device of claim 5, wherein said region comprises a semiconductor layer adjacent said medium, said semiconductor layer having an inversion layer in contact with said piezoelectric medium, wherein said semiconductor layer is electrically connected to an electrical source for periodically varying the conductivity of said semiconductor layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |