PLANAR OPTICAL WAVEGUIDE

• US 3,806,223 A
• Filed: 03/30/1972
• Issued: 04/23/1974
• Est. Priority Date: 03/30/1972
• Status: Expired due to Term

• Current Assignee: Donald B. Keck, Peter C. Schultz
• Original Assignee: Donald B. Keck, Peter C. Schultz
• Inventors: Keck, Donald B., Schultz, Peter C.
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US05/239,701
• Time in Patent Office: 754 Days
• Field of Search: 350/96WG
• US Class Current: 385/129
• CPC Class Codes: C03B 19/14 by gas- or vapour- phase reaction processes
• CPC Class Codes: C03B 37/014 made entirely or partially by chemical means , e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] C03C17/02 takes precedence
• CPC Class Codes: C03C 17/02 with glass C03C17/34, C03C17/44 take precedence
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 23/0025 by a laser beam
• CPC Class Codes: G02B 6/13 Integrated optical circuits characterised by the manufacturing method

Abstract

A method of producing a planar optical waveguide by applying to at least a portion of one flat surface of a substantially flat glass substrate having a predetermined desired index of refraction a first coating of glass having an index of refraction greater than that of said glass substrate. Thereafter a second coating of glass having an index of refraction less than that of the first coating of glass is applied over the exposed surface of the first coating of glass. The thickness of the first coating of glass being determined as a function of the highest mode order and the wavelength of light to be propagated within a waveguide having infinite width, and the indices of refraction of the substrate and each of the applied coatings.

Claims

2. The planar optical waveguide of claim 1 wherein said first and second applied coatings are sintered flame hydrolysis deposits.

3. The planar optical waveguide of claim 1 wherein said first coating is doped fused silica and said second coating is a material selected from the group consisting of pure fused silica and fused silica doped to a lesser degree than the material of said first coating.

4. The planar optical waveguide of claim 3 wherein said first coating is fused silica doped with at least one material selected from the group consisting of titanium oxide, tantalum oxide, tin oxide, niobium oxide, zirconium oxide, aluminum oxide, lanthanum oxide, and germanium oxide.

5. The planar optical waveguide of claim 3 wherein said first coating is fused silica doped with not more than 20 percent by weight titanium oxide.

6. The planar optical waveguide of claim 1 wherein the width to thickness ratio of said first coating is equal to or less than ten.

7. A planar optical waveguide for light propagation comprising a substantially flat glass substrate having a predetermined desired index of refraction. a first applied coating of glass having an index of refraction greater than that of said glass substrate deposited on and adhered to at least a portion of one flat surface of said substrate, said first coating of glass having an outer exposed surface substantially parallel to said one flat surface of said substrate, the thickness of said first coating being defined by said surfaces, the width of said first coating being the dimension perpendicular to both said thickness and the light propagation axis of said first coating, and a second applied coating of glass having an index of refraction substantially equal to that of said substrate deposited on at least one said outer exposed surface of said first coating of glass and adhered thereto, the thickness of said first coating of glass for any desired finite width thereof being equal to or less than the thickness '"'"''"'"''"'"''"'"'a'"'"''"'"''"'"''"'"' of a coating having infinite width, thickness '"'"''"'"''"'"''"'"'a'"'"''"'"''"'"''"'"' being determined in accordance with the following equation 2a/ lambda (n22 - n12)1/2 m + 1 where m <

or = 10 and is the highest mode order to be propagated within a waveguide the first coating of which has a thickness '"'"''"'"''"'"''"'"'a'"'"''"'"''"'"''"'"' and an infinite width, lambda is the cutoff wavelength of light to be propagated within said waveguide the first coating of which has a thickness '"'"''"'"''"'"''"'"'a'"'"''"'"''"'"''"'"' and an infinite width, n2 is the index of refraction of said first coating, and n1 is the index of refraction of said substrate and said substrate and said second coating of glass, said thickness of said first coating of glass being so determinable where the propagation constant of said waveguide is equal to or less than K1, where K1 2 pi n1/ lambda , and thE thickness of each of said substrate and said second coating of glass being at least about two times the thickness of said first coating of glass, whereas said first coating of glass forms the planar waveguide core, and said substrate and said second coating form the planar waveguide cladding,

8. The planar optical waveguide of claim 7 wherein said first and second applied coatings are sintered flame hydrolysis deposits.

9. The planar optical waveguide of claim 7 wherein said first coating is doped fused silica and said second coating is a material selected from the group consisting of pure fused silica and fused silica doped to a lesser degree than the material of said first coating.

10. The planar optical waveguide of claim 9 wherein said first coating is fused silica doped with at least one material selected from the group consisting of titanium oxide, tantalum oxide, tin oxide, niobium oxide, zirconium oxide, aluminum oxide, lanthanum oxide, and germanium oxide.

11. The planar optical waveguide of claim 9 wherein said first coating is fused silica doped with not more than 20 percent by weight titanium oxide.

12. The planar optical waveguide of claim 7 wherein the width to thickness ratio of said first coating is equal to or less than ten.