US4243295A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polarization-independent optical directional coupler switch/modulator
Assignee: AT&T Inc
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Filing: 1979-09-19
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Granted: 1981-01-06
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Expires: 1999-09-19
Abstract
Abstract Because orthogonally polarized optical waves see unequal electrooptic coefficients and refractive indices for the same applied voltage, it has been difficult to obtain efficient switching of arbitrarily polarized waves. This difficulty is resolved in a reverse Δβ directional coupler (10, 11) which employs spatial tapering of the distance between waveguides (D(z)) for efficient through-coupling, and the appropriate choice of effective coupling strengths (s TE , s TM ) for the two polarizations for efficient cross-coupling.
Inventors
- 👤 Rodney C. Alferness
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:46
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/31; G02F1/313; G02F1/3132; G02F2201/00; G02F2201/12; G02F2201/125; G02F2203/00; G02F2203/06
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
124 words
A switch/modulator comprising: a pair of optical waveguides (10,11) supportive of TE and TM propagating modes having an interaction length L and coefficients of coupling for said modes that taper from a minimum at the ends of said waveguides to a maximum at a point therebetween; and means (13,14,15) for impressing voltages (V 1 , V 2 ) across selected portions of said waveguides; characterized in that: the waveguide parameters are such that the resulting normalized integrated coupling strengths 2s TE /π and 2s TM /π for said modes are between 1 and 1.3 or between 2.7 and 3; and in that s TM >s TE in the region 1 to 1.3; and s TM <s TE in the region of 2.7 to 3.
Claim 2
Dependent Claim
124 words
A switch/modulator comprising: a pair of optical waveguides (10,11) supportive of TE and TM propagating modes having an interaction length L and coefficients of coupling for said modes that taper from a minimum at the ends of said waveguides to a maximum at a point therebetween; and means (13,14,15) for impressing voltages (V 1 , V 2 ) across selected portions of said waveguides; characterized in that: the waveguide parameters are such that the resulting normalized integrated coupling strengths 2s TE /π and 2s TM /π for said modes are between 1 and 1.3 or between 2.7 and 3; and in that s TM >s TE in the region 1 to 1.3; and s TM <s TE in the region of 2.7 to 3.
Claim 3
Dependent Claim
22 words
The switch/modulator according to claim 1 wherein V 1 =V 2 for straight-through transmission and V 1 =-V 2 for crossover transmission.
Claim 4
Dependent Claim
20 words
The switch/modulator according to claim 1 wherein the coupling coefficient k(z) is given by ##EQU4## where A is a constant.
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) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |