US3820087A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Three dimensional memory
Assignee: International Business Machines Corp
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Filing: 1972-12-29
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Granted: 1974-06-25
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Expires: 1992-12-29
Abstract
Abstract A three dimensional memory using materials switchable from an amorphous state to a crystalline state and back again to its amorphous state is realized by focusing a laser beam into different depths of the material. The material, when in its crystalline state, is capable of generating the harmonic of the frequency of the incident light used to interrogate its state, whereas in its amorphous state it is not a generator of harmonics. The detection of this harmonic allows for increased discrimination in the data reading process.
Inventors
- 👤 P Chaudhari
- 👤 C Zarowin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:17
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/048
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
158 words
A three dimensional memory comprising a solid material capable of having selected spots therein altered from an amorphous state to its crystalline state, a laser source of a given frequency focusable within different depths of said material and having sufficient energy for altering said selected spot from its amorphous state to its crystalline state, such alteration producing a condition capable of generating second harmonics means for interrogating and traversing such selected spot with the same frequency focused laser beam having considerably less energy than said material phase-changing beam so that a second harmonic of said laser frequency is generated by said selected spot of material if the latter is in its crystalline state but no second harmonic generation occurs if it is in the amorphous state when said less energetic beam traverses said selected spot, and means for detecting the presence of said second harmonic frequency within said interrogating beam after the latter has traversed said selected spot.
Claim 2
Dependent Claim
158 words
A three dimensional memory comprising a solid material capable of having selected spots therein altered from an amorphous state to its crystalline state, a laser source of a given frequency focusable within different depths of said material and having sufficient energy for altering said selected spot from its amorphous state to its crystalline state, such alteration producing a condition capable of generating second harmonics means for interrogating and traversing such selected spot with the same frequency focused laser beam having considerably less energy than said material phase-changing beam so that a second harmonic of said laser frequency is generated by said selected spot of material if the latter is in its crystalline state but no second harmonic generation occurs if it is in the amorphous state when said less energetic beam traverses said selected spot, and means for detecting the presence of said second harmonic frequency within said interrogating beam after the latter has traversed said selected spot.
Claim 3
Dependent Claim
16 words
The three dimensional memory of claim 1 wherein the storage material is an amorphous semiconductor chalcogenide.
Claim 4
Dependent Claim
12 words
The three dimensional memory of claim 2 wherein the chalcogenide is Te85Ge11As14.
Claim 5
Dependent Claim
157 words
A three dimensional memory comprising a solid material capable of having selected spots therein alterable from an amorphous state to its crystalline state by the application of a focused high energy laser beam at a selected spot, a confocal Fabry-Perot cavity having mirrors bounding said cavity, both mirrors being transparent to a given frequency f but reflective at frequency 2f, said transparent solid material located substantially at the center of said cavity, means for applying said focused high energy laser beam of a frequency f through a first of said mirrors onto a selected spot in said material for changing its state, and means for applying the same f frequency but considerably less energetic beam through said same first mirror to a selected spot of said material to interrogate said spot whereby the latter will generate a frequency 2f if it is in iTs crystalline state, which frequency is amplified by the mirrors of said confocal cavity.
Claim 6
Dependent Claim
157 words
A three dimensional memory comprising a solid material capable of having selected spots therein alterable from an amorphous state to its crystalline state by the application of a focused high energy laser beam at a selected spot, a confocal Fabry-Perot cavity having mirrors bounding said cavity, both mirrors being transparent to a given frequency f but reflective at frequency 2f, said transparent solid material located substantially at the center of said cavity, means for applying said focused high energy laser beam of a frequency f through a first of said mirrors onto a selected spot in said material for changing its state, and means for applying the same f frequency but considerably less energetic beam through said same first mirror to a selected spot of said material to interrogate said spot whereby the latter will generate a frequency 2f if it is in iTs crystalline state, which frequency is amplified by the mirrors of said confocal cavity.
Claim 7
Dependent Claim
27 words
The three dimensional memory of claim 4 wherein the second of said pair of mirrors in the Fabry-Perot cavity is partially transmissive to the harmonic frequency 2f.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |