US4372642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple thin film absorption of reflected substrate modes in waveguide system
Assignee: United States Department of the Navy
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Filing: 1980-11-25
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Granted: 1983-02-08
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Expires: 2000-11-25
Abstract
Abstract Reduction of light reflections in substrate modes. The use of absorbing multilayer thin-film light interference coatings on the backside of a LiNbO3 substrate provides an optical system which substantially reduces reflected substrate modes in integrated optical spectrum analyzers at around 8300 A wavelength, or at other selected wavelengths, over a broad range of incident angles by selection of individual film thickness and optical constants.
Inventors
- 👤 Arnold H. Singer
- 👤 Ronald T. Holm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:27
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/16; G01R23/177; G02; G02F; G02F1/00; G02F1/01; G02F1/11; G02F1/125
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
73 words
An optical waveguide system with reduced substrate reflections comprising: a substrate; a thin-film optical waveguide on the frontside of the substrate for carrying light therethrough; and an absorbing antireflective multilayer coating on the backside of the substrate; whereby light of substantially a single wavelength having leaked into the substrate and incident to the backside of the substrate over a broad range of angles is substantially absorbed by the antireflecting coating with minimal reflection.
Claim 2
Dependent Claim
73 words
An optical waveguide system with reduced substrate reflections comprising: a substrate; a thin-film optical waveguide on the frontside of the substrate for carrying light therethrough; and an absorbing antireflective multilayer coating on the backside of the substrate; whereby light of substantially a single wavelength having leaked into the substrate and incident to the backside of the substrate over a broad range of angles is substantially absorbed by the antireflecting coating with minimal reflection.
Claim 3
Dependent Claim
21 words
The invention according to claim 1 where the broad range of incident angles varies from near normal up to about 76°.
Claim 4
Dependent Claim
13 words
The invention according to claim 1 wherein the substrate is LiNbO 3 .
Claim 5
Dependent Claim
24 words
The invention according to claim 3 wherein the thin-film optical waveguide is defined by Ti diffused into the frontside of the LiNbO 3 substrate.
Claim 6
Dependent Claim
68 words
The invention according to claim 1, 3 or 4 wherein the absorbing antireflective multilayer coating includes a transparent first layer on the substrate and has an index of refraction greater than n, where n is calculated according to the formula n=n.sub.s sin θ.sub.m where n s =index of refraction of the substrate, and θ m =maximum angle of incidence; and, layers outward of the first layer are lossy.
Claim 7
Dependent Claim
12 words
The invention according to claim 5 wherein the first layer is ZnS.
Claim 8
Dependent Claim
19 words
The invention according to claim 5 wherein the lossy layers are progressively more lossy outwardly from the first layer.
Claim 9
Dependent Claim
18 words
The invention according to claim 5 or 7 wherein the first lossy layer has an extinction coefficient k<n.
Claim 10
Dependent Claim
22 words
The invention according to claim 8 wherein the second lossy layer outward of the first lossy layer has an extinction coefficient k>n.
Claim 11
Dependent Claim
28 words
The invention according to claim 9 where the value of k of the second lossy layer is over two times the value of n of the same layer.
Claim 12
Dependent Claim
22 words
The invention according to claim 7 or 10 wherein the first lossy layer and second lossy layer are Ge and Al, respectively.
Claim 13
Dependent Claim
90 words
An optical waveguide system with reduced substrate reflections comprising: a substrate; a thin-film optical waveguide on the frontside of the substrate for carrying light therethrough; and an absorbing antireflective coating on the backside of the substrate comprising: a first layer of transparent material; a second layer of material being moderately lossy; and a third layer of material being highly lossy; whereby light of substantially a single wavelength having leaked into the substrate and incident to the backside thereof over a broad range of angles is substantially absorbed with minimal reflection.
Claim 14
Dependent Claim
90 words
An optical waveguide system with reduced substrate reflections comprising: a substrate; a thin-film optical waveguide on the frontside of the substrate for carrying light therethrough; and an absorbing antireflective coating on the backside of the substrate comprising: a first layer of transparent material; a second layer of material being moderately lossy; and a third layer of material being highly lossy; whereby light of substantially a single wavelength having leaked into the substrate and incident to the backside thereof over a broad range of angles is substantially absorbed with minimal reflection.
Claim 15
Dependent Claim
14 words
The invention according to claim 12 wherein the second layer material is semiconductor material.
Claim 16
Dependent Claim
12 words
The invention according to claim 13 wherein the second layer is Ge.
Claim 17
Dependent Claim
15 words
The invention according to claim 12 or 13 wherein the third layer material is metallic.
Claim 18
Dependent Claim
12 words
The invention according to claim 15 wherein the third layer is Al.
Claim 19
Dependent Claim
13 words
The invention according to claim 12 wherein the substrate is LiNbO 3 .
Claim 20
Dependent Claim
18 words
The invention according to claim 17 wherein the optical waveguide is Ti diffused into the LiNbO 3 substrate.
Claim 21
Dependent Claim
60 words
The invention according to claim 12, 17 or 18 wherein the first layer of transparent material has an index of refraction n t where the value of n t is greater than that calculated according to the formula n=n s sin θ m , where n s =index of refraction of the substrate, and θ m =maximum angle of incidence.
Claim 22
Dependent Claim
12 words
The invention according to claim 12 wherein the transparent material is ZnS.
Claim 23
Dependent Claim
19 words
The invention according to claim 12 wherein the first, second and third layers are ZnS, Ge and Al, respectively.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |