US3883219A
Expired / Lapsed
US
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Dielectric optical waveguide
Assignee: AT&T Inc
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Filing: 1973-12-26
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Granted: 1975-05-13
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Expires: 1993-12-26
Abstract
Abstract A method of fabricating dielectric optical waveguides comprises the steps of: (1) fabricating a single or double heterostructure from the GaAs-AlGaAs system preferably by liquid phase epitaxy or molecular beam epitaxy; (2) forming a native oxide layer on the top surface of the heterostructure by anodization in H2O2; (3) removing a portion of the oxide layer to form a mask and hence to define the waveguide shape in the direction of light propagation; and (4) forming a mesa-like structure with optically flat side walls by etching at a slow rate in Br2-CH3OH. After step (4) two alternative techniques leading to structurally different waveguides may be followed. In one technique, an AlGaAs layer is epitaxially grown over the mesa to form a two dimensional waveguide. In the other technique, the edges of the active region of an AlGaAs double heterostructure are differentially etched in a neutral solution of H2O2. The latter step is particularly useful in the fabrication of active devices because the resulting structure is self-masking, thereby facilitating the formation of electrical contacts.
Inventors
- 👤 Ralph Andre Logan
- 👤 Bertram Schwartz
- 👤 Jr Joseph Charles Tracy
- 👤 William Wiegmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:31
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/01; H10H20/011; H10H20/013; G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/13; G02B6/131; H01; H01S; H01S5/00; H01S5/20; H01S5/22; Y; Y10; Y10S; Y10S148/00; Y10S148/051; Y10S148/067; Y10S148/072; Y10S148/118
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
91 words
A DIELECTRIC OPTICAL WAVEGUIDE COMPRISING: A GAAS SUBSTRATE HAVING FIRST AND SECOND MAJOR SURFACES, A MULTILAYERED STRUCTURE COMPRISING THE FOLLOWING LAYERS EPITAXIALLY GROWN ON SAID FIRST MAJOR SURFACE IN THE ORDER RECITED: A AL2GA1-2AS FIRST LAYER AT LEAST ONE ALYGA1-GAS MIDDLE LAYER, AND A AL2GA1-2AS THIRD LAYER, Y<X AND Z? THE WIDTH OF SAID MIDDLE LAYER MEASURED PARALLEL TO SAID FIRST MAJOR SURFACE, BEING LESS THAN THE CORRESPONDING WIDTH OF SAID FIRST AND THIRD LAYERS SO THAT SAID LATTER LAYERS HAVE PORTIONS WHICH OVERHANG THE EDGES OF THE SAID MIDDLE LAYER.
Claim 2
Dependent Claim
91 words
A DIELECTRIC OPTICAL WAVEGUIDE COMPRISING: A GAAS SUBSTRATE HAVING FIRST AND SECOND MAJOR SURFACES, A MULTILAYERED STRUCTURE COMPRISING THE FOLLOWING LAYERS EPITAXIALLY GROWN ON SAID FIRST MAJOR SURFACE IN THE ORDER RECITED: A AL2GA1-2AS FIRST LAYER AT LEAST ONE ALYGA1-GAS MIDDLE LAYER, AND A AL2GA1-2AS THIRD LAYER, Y<X AND Z? THE WIDTH OF SAID MIDDLE LAYER MEASURED PARALLEL TO SAID FIRST MAJOR SURFACE, BEING LESS THAN THE CORRESPONDING WIDTH OF SAID FIRST AND THIRD LAYERS SO THAT SAID LATTER LAYERS HAVE PORTIONS WHICH OVERHANG THE EDGES OF THE SAID MIDDLE LAYER.
Claim 3
Dependent Claim
79 words
The waveguide of claim 1 wherein said middle layer forms the active region of an active device and said overhanging portions form air gaps therebetween, and further including a first electrical contact formed over the surface of said waveguide which includes said third layer, said first contact being bifurcated at said air gaps so that said active region is not short-circuited by said first contact, and a second electrical contact formed on said second major surface of said substrate.
Claim 4
Dependent Claim
71 words
The waveguide of claim 1 wherein said multilayered structure has, in a plane perpendicular to the direction of light propagation therethrough, a mesa-like cross-section which is made substantially uniform over an extended length of said waveguide, and which has side walls which are made optically flat, by etching said structure at a slow rate in a bromine methanol solution containing approximately 0.5 to 1.0 parts bromine per 1, 000 by volume.
Claim 5
Dependent Claim
81 words
The waveguide of claim 3 wherein the width of said middle layer is made smaller than that of said first and third layers by bringing said structure into contact with a solution of H2O2 in water buffered to a pH in the range of about 6 to 8, said solution differentially etch said middle layer at a faster rate than said first and third layers, so that said first and third layers overhang said middle layer and create air gaps therebetween.
Claim 6
Dependent Claim
14 words
The waveguide of claim 4 wherein said solution has a pH of about 7.05.
Claim 7
Dependent Claim
14 words
The waveguide of claim 14 wherein y 0 and said middle layer comprises GaAs.
Claim 8
Dependent Claim
55 words
The waveguide of claim 4 wherein said first major surface of said GaAs substrate is parallel to a (100) crystallographic plane, the plane of said cross-section is parallel to the (011) cleavage plane of GaAs, and said side walls are parallel to (111) crystallographic planes which are preferentially etched by said solution of bromine methanol.
Claim 9
Dependent Claim
166 words
A dielectric optical waveguide having along its length a mesa-like cross-section in a plane perpendicular to the direction of light propagation therethrough, comprising a GaAs substrate, a heterostructure epitaxially grown on said substrate, said heterostructure including at least an AlxGa1 xAs first layer, x > 0, grown on said substrate and an AlyGa1 yAs second layer, 0 < or = y < x, grown on said first layer and being adapted for the propagation of light therethrough, said heterostructure having the shape of a mesa formed by bringing said heterostructure into contact with a solution of bromine methanol containing about 0.05 to 0.1 percent bromine, said solution being effective to produce optically flat side walls on said mesa and a substantially uniform cross-section along the length of said waveguide, and an AlqGa1 qAs, q > y, third layer epitaxially grown on said heterostructure so that said second layer is bounded on four sides by AlGaAs layers having more aluminum therein, thereby to form a two-dimensional waveguide.
Claim 10
Dependent Claim
166 words
A dielectric optical waveguide having along its length a mesa-like cross-section in a plane perpendicular to the direction of light propagation therethrough, comprising a GaAs substrate, a heterostructure epitaxially grown on said substrate, said heterostructure including at least an AlxGa1 xAs first layer, x > 0, grown on said substrate and an AlyGa1 yAs second layer, 0 < or = y < x, grown on said first layer and being adapted for the propagation of light therethrough, said heterostructure having the shape of a mesa formed by bringing said heterostructure into contact with a solution of bromine methanol containing about 0.05 to 0.1 percent bromine, said solution being effective to produce optically flat side walls on said mesa and a substantially uniform cross-section along the length of said waveguide, and an AlqGa1 qAs, q > y, third layer epitaxially grown on said heterostructure so that said second layer is bounded on four sides by AlGaAs layers having more aluminum therein, thereby to form a two-dimensional waveguide.
Claim 11
Dependent Claim
40 words
The waveguide of claim 8 including an AlzGa1 zAs fourth layer, z > y, grown on said second layer, said AlqGa1 qAs third layer being grown on said AlzGa1 zAs fourth layer and on the side walls of said mesa.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |