US4381139A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Velocity mismatched modulator
Assignee: AT&T Inc
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Filing: 1980-08-29
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Granted: 1983-04-26
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Expires: 2000-08-29
Abstract
Abstract The coupling efficiency between a pair of identical optical waveguides (11, 12) is modulated by a traveling electrical wave (14, 15). Because the propagating constants of the optical and modulating systems are not equal, the interaction between them is limited to periodic intervals along the optical wavepaths. By the appropriate selection of this spatial period, a velocity match between the modulating and optical systems is simulated.
Inventors
- 👤 Rodney C. Alferness
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:40
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/31; G02F1/313; G02F1/3132; G02F1/3134
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
81 words
A modulator (10) comprising: a pair of substantially identical optical waveguides (11, 12) embedded in a substrate (13) of electrooptic material of lower refractive index; said optical waveguides being in coupling relationship over a distance L; and modulating means (14, 15), supportive of a traveling wave, for locally changing the propagation constants (β 1 , β 2 ) of at least one of said waveguide (11, 12) at longitudinally spaced intervals (14-1, 15-1; 14-2, 15-2; . . . 14-n; 15-n) therealong.
Claim 2
Dependent Claim
81 words
A modulator (10) comprising: a pair of substantially identical optical waveguides (11, 12) embedded in a substrate (13) of electrooptic material of lower refractive index; said optical waveguides being in coupling relationship over a distance L; and modulating means (14, 15), supportive of a traveling wave, for locally changing the propagation constants (β 1 , β 2 ) of at least one of said waveguide (11, 12) at longitudinally spaced intervals (14-1, 15-1; 14-2, 15-2; . . . 14-n; 15-n) therealong.
Claim 3
Dependent Claim
20 words
The modulator according to claim 1 wherein the spatial period, Λ, of said intervals is uniform over said distance L.
Claim 4
Dependent Claim
43 words
The modulator according to claim 2 wherein said period, Λ, is given by ##EQU13## where n o , n e are the effective refractive indices at an optical signal wavelength λ o , and at a modulating signal wavelength λ e , respectively.
Claim 5
Dependent Claim
41 words
The modulator according to claim 1 wherein said period Λ varies over said distance L between a first value Λ o at one end of said modulator to a second value Λ o +ΔΛ at the other end of said modulator.
Claim 6
Dependent Claim
49 words
The modulator according to claim 1 wherein said modulating means comprises a pair of electrodes (14, 15), at least one of which is provided with a plurality of fingers (14-1, 14-2 . . . 14-n) which extend over one of said waveguides (11) towards the other of said electrodes.
Claim 7
Dependent Claim
29 words
The modulator according to claim 1 wherein said modulating means comprises a pair of electrodes (14, 15) for producing periodic regions of electric field within said waveguides (11, 12).
Claim 8
Dependent Claim
40 words
The modulator according to claim 6 wherein said electrodes (14, 15) have fingers (14-1, 14-2 . . . 14-n; 15-1, 15-2 . . . 15-n) whose ends are symmetrically positioned above said waveguides (11, 12) and directly opposite each other.
Claim 9
Dependent Claim
39 words
The modulator according to claim 6 including a third electrode (18) disposed adjacent to one (14) of said pair of electrodes, and a fourth electrode (19) disposed adjacent to the other (15), of said electrodes for tuning said modulator.
Claim 10
Dependent Claim
19 words
The modulator according to claim 1 wherein the coefficient of coupling, κ, between said waveguides is given by κL=π/2.
References Cited (Backward Citations)
US3995311A
Cited
US4236785A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-04-25 | 1986-10-25 | 1987-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-04-25 | 1990-10-25 | 1991-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-04-25 | 1994-10-25 | 1995-04-26 | $7700.00 | Window Closed / Lapsed |