US4709977A
Expired / Lapsed
US
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Controllable directional coupler
Assignee: Siemens AG
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Filing: 1985-04-16
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Granted: 1987-12-01
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Expires: 2005-04-16
Abstract
Abstract A controllable directional coupler comprises two optical waveguides on the surface of a substrate of electrooptical material, the waveguides extending parallel for a predetermined distance. The coupler also comprises a control electrode structure including a pair of control electrodes formed on the surface of the substrate and covering the two parallel waveguides along their lengths. In order to achieve low control voltage and a low coupling loss, in the case of butt coupling to a monomode fiber, in the interstice between the two optical waveguides, the refractive index of the substrate is reduced to a specific depth of the substrate at which the coupling intensity becomes largely independent of the near-field expansion in the waveguides.
Inventors
- 👤 Franz Auracher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:24
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/31; G02F1/313; G02F1/3132; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
118 words
In a controllable directional coupler of the type in which a pair of light waveguides extend parallel to one another for a length L at a surface of a substrate of electro-optical material defining an interstice therebetween, and in which a control electrode structure is carried on the surface of the substrate and comprises a pair of spaced control electrodes respectively positioned over respective ones of said waveguides, the improvement therein comprising: a zone in the interstice having a lower refractive index down to a predetermined depth with respect to the remainder of the substrate, whereby the lower refractive index and the predetermined depth are selected such that a cross over between the two wave guides still occurs.
Claim 2
Dependent Claim
118 words
In a controllable directional coupler of the type in which a pair of light waveguides extend parallel to one another for a length L at a surface of a substrate of electro-optical material defining an interstice therebetween, and in which a control electrode structure is carried on the surface of the substrate and comprises a pair of spaced control electrodes respectively positioned over respective ones of said waveguides, the improvement therein comprising: a zone in the interstice having a lower refractive index down to a predetermined depth with respect to the remainder of the substrate, whereby the lower refractive index and the predetermined depth are selected such that a cross over between the two wave guides still occurs.
Claim 3
Dependent Claim
16 words
The improved directional coupler of claim 1, wherein: said zone comprises a channel in the substrate.
Claim 4
Dependent Claim
14 words
The improved directional coupler of claim 1, wherein: said zone comprises doped substrate material.
Claim 5
Dependent Claim
113 words
In a method of making a directional coupler which comprises a pair of light waveguides extending parallel to one another at a surface of a substrate of electro-optical material and defining an interstice therebetween, and a control electrode structure carried on the surface and including a pair of spaced electrodes respectively located over respective ones of the waveguides, the improvement comprising the step of: lowering the refractive index of the substrate material in the interstice to a predetermined depth with respect to the refractive index of the remainder of the substrate, including selecting the refractive index in the interstice and the predetermined depth such that a crossover between the two waveguides still occurs.
Claim 6
Dependent Claim
113 words
In a method of making a directional coupler which comprises a pair of light waveguides extending parallel to one another at a surface of a substrate of electro-optical material and defining an interstice therebetween, and a control electrode structure carried on the surface and including a pair of spaced electrodes respectively located over respective ones of the waveguides, the improvement comprising the step of: lowering the refractive index of the substrate material in the interstice to a predetermined depth with respect to the refractive index of the remainder of the substrate, including selecting the refractive index in the interstice and the predetermined depth such that a crossover between the two waveguides still occurs.
Claim 7
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: wet-chemical etching a channel in the substrate.
Claim 8
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: dry-chemical etching a channel in the substrate.
Claim 9
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: ion etching a channel in the substrate.
Claim 10
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: plasma etching a channel in the substrate.
Claim 11
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: ion implanting a channel in the substrate.
Claim 12
Dependent Claim
25 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: ion exchanging a channel in the substrate.
Claim 13
Dependent Claim
45 words
The improved method of claim 4, wherein the substrate is LiNbO 3 and wherein: the step of lowering the refractive index is further defined as: placing the substrate in a fluorous molecular gas environment, and ion etching a channel in the substrate in the gas.
Claim 14
Dependent Claim
45 words
The improved method of claim 4, wherein the substrate is LiNbO 3 and wherein: the step of lowering the refractive index is further defined as: placing the substrate in a CHF 3 gas environment, and ion etching a channel in the substrate in the gas.
Claim 15
Dependent Claim
24 words
The improved method of claim 4, wherein: the step of lowering the refractive index is further defined as: doping the substrate at the interstice.
References Cited (Backward Citations)
US3936144A
Cited
US4583817A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-30 | 1991-06-01 | 1991-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-30 | 1995-06-01 | 1995-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-30 | 1999-06-01 | 1999-12-01 | $7700.00 | Window Closed / Lapsed |