Patent US4262992A successfully refreshed from Google Patents.
US4262992A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable integrated optical logic element
Assignee: National Security Agency
•
Filing: 1979-04-18
•
Granted: 1981-04-21
•
Expires: 1999-04-18
Abstract
Abstract A variable integrated optical logic element, formed on a substrate of electro-optic material, capable of being controlled to perform the six basic logic operations AND, OR, EXCLUSIVE OR, NAND, NOR and EXCLUSIVE NOR. The optical logic element comprises a plurality of single-mode optical waveguides which form a group of parallel and series equal-arm interferometers. The optical logic element operates on the principle of constructive and destructive interference between light beams. Voltage means are provided for varying the index of refraction of certain of the optical waveguides, to produce relative phase differences in the light energy propagating therein. By inducing phase shifts in the light energy propagating in appropriate waveguides, each of the six basic logic operations can be performed. Also disclosed is an electrically passive, phase-sensitive optical coupler, which is used for switching light energy between waveguides. The switching operation performed by the phase-sensitive coupler is a function of the presence or absence of and the relative phase differences between the light energy input to the coupler.
Inventors
- 👤 John W. Berthold, III
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:35
CPC Classifications
G; G02; G02F; G02F3/00; G02F1/00; G02F1/29; G02F1/31; G02F1/313; G02F1/3137
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
122 words
An optical logic element comprising: Two or more single-mode input optical waveguides for inputting lowest order single-mode optical energy; a single-mode output optical waveguide for outputting lowest order single-mode optical energy representative of a logic operation performed on said input optical energy; a plurality of single-mode optical waveguide paths of equal optical lengths interconnecting said input and output optical waveguides, said paths including means for switching light energy in certain of said paths to certain other of said paths; and means for varying the optical length of predetermined ones of said paths such that the phase of the light energy propagating in said predetermined paths may be shifted relative to the phase of the light energy propagating in other of said paths.
Claim 2
Dependent Claim
122 words
An optical logic element comprising: Two or more single-mode input optical waveguides for inputting lowest order single-mode optical energy; a single-mode output optical waveguide for outputting lowest order single-mode optical energy representative of a logic operation performed on said input optical energy; a plurality of single-mode optical waveguide paths of equal optical lengths interconnecting said input and output optical waveguides, said paths including means for switching light energy in certain of said paths to certain other of said paths; and means for varying the optical length of predetermined ones of said paths such that the phase of the light energy propagating in said predetermined paths may be shifted relative to the phase of the light energy propagating in other of said paths.
Claim 3
Dependent Claim
31 words
The optical element of claim 1 wherein the logic operation performed by the optical element is a function of the phase shifts applied to the light energy propagating in said paths.
Claim 4
Dependent Claim
52 words
The optical element of claim 2 wherein said means for varying the optical lengths of said paths includes means for independently varying the optical lengths of said paths such that the optical element can be controlled to operate, alternatively, as an AND, OR, EXCLUSIVE OR, NAND, NOR or EXCLUSIVE NOR logic gate.
Claim 5
Dependent Claim
41 words
The optical element of claim 1 wherein said means for varying the optical length of predetermined ones of said paths includes means for varying the index of refraction of said paths, thereby varying the velocity of the optical energy propagating therein.
Claim 6
Dependent Claim
56 words
The optical element of claim 4 wherein said optical element is formed on a substrate of electro-optic material and said means for varying the index of refraction of said paths comprises means for applying an electric field to a portion of the length of said paths over which the index of refraction is to be varied.
Claim 7
Dependent Claim
29 words
The optical element of claim 1 further comprising balancing means for adjusting the lengths of said waveguide paths to compensate for differences in optical lengths resulting from fabrication variances.
Claim 8
Dependent Claim
50 words
The optical element of claim 6 wherein said optical element is constructed from electro-optic material and said balancing means includes means for applying electric fields to said paths to vary their index of refraction in order to compensate for differences in the velocity of propagation of the optical energy therein.
Claim 9
Dependent Claim
47 words
The optical element of claim 1 wherein said plurality of waveguide paths form a group of parallel and series equalarm interferometers and said logic operation performed by the optical element is the result of constructive and destructive interference between the light energy propagating in said waveguide paths.
Claim 10
Dependent Claim
29 words
The optical element of claim 1 wherein said switching means comprise a passive, phase-sensitive optical coupler, the outputs of which are a function of the inputs to said coupler.
Claim 11
Dependent Claim
123 words
The optical element of claim 9 wherein said phasesensitive optical coupler comprises: a multi-mode tapered optical waveguide section for propagating zero-order and first-order optical energy; a pair of single-mode input optical waveguides converging at the input to said multi-mode waveguide for inputting single-mode optical energy; and single-mode output optical waveguides diverging from the output of said multi-mode waveguide for outputting singlemode optical energy; said multi-mode optical waveguide having an optical length such that zero-order optical energy at the output of said multi-mode waveguide is in-phase with zero-order optical energy at the input to said multi-mode waveguide, whereas first-order optical energy at the output of said multi-mode waveguide is π out of phase with first-order optical energy at the input to said multi-mode waveguide.
Claim 12
Dependent Claim
88 words
The optical element of claim 10 wherein said singlemode output optical waveguides comprise first, second and third single-mode waveguides diverging from the output of said multi-mode waveguide, said third single-mode waveguide being a terminated waveguide section disposed between said first and second waveguides, and wherein said phase-sensitive optical coupler is characterized in that zero-order optical energy propagating in said multi-mode waveguide is coupled primarily to said third output waveguide, whereas firstorder optical energy propagating in said multi-mode waveguide is coupled primarily to said first and second output waveguides.
Claim 13
Dependent Claim
41 words
The optical element of claim 1 wherein the speed of said logic operation is limited by the pulse width of said optical energy and the propagation delay of said optical energy between the inputs and the output of the optical element.
References Cited (Backward Citations)
US3781081A
Cited
US3849740A
Cited
US3909108A
Cited
US4008947A
Cited
US4087159A
Cited
US4070094A
Cited
US3995311A
Cited
US4012113A
Cited
US4070092A
Cited
US4130342A
Cited
US4128300A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-20 | 1984-10-20 | 1985-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-20 | 1988-10-20 | 1989-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-20 | 1992-10-20 | 1993-04-21 | $7700.00 | Window Closed / Lapsed |