Tapered rib waveguides
AssigneeBell Communications Research, Inc.
InventorsElyahou Kapon, Arie Shahar, Robert N. Thurston
Life of this patent
Estimating the term…
Abstract
A tapered single-mode rib waveguide for which only laterally patterning is required. A sublayer is disposed between the low-index substrate and the high-index rib and has an intermediate index. Preferably a thin buffer layer of very low refractive index is disposed between the rib and the sublayer. The widths of the rib are chosen so that in a wide portion the optical power of the single-mode is concentrated in the rib or buffer layer but in a narrow portion the optical power is concentrated in the sublayer or substrate and additionally has a wide lateral distribution. A similar effect can be obtained by tapering an upper rib disposed on top of an untapered lower rib.
Claims9
A tapered single-mode rib waveguide, comprising:
- a substrate having a first refractive index;
- a sublayer formed on said substrate and having a second refractive index greater than said first refractive index;
- a buffer layer formed on said sublayer and having a third refractive index less than or equal to said second refractive index;
- and
- a tapered rib formed on said buffer layer and having a fourth refractive index greater than or equal to said second refractive index, wherein said tapered rib comprises a first longitudinally untapered portion of a first cross-section and a longitudinally tapered portion smoothly connected to said first portion and flaring laterally outward therefrom.
A tapered single-mode rib waveguide, comprising:
- a substrate of a first refractive index;
- a first rib of a second refractive index greater than said first refractive index formed on said substrate and longitudinally extending along a surface thereof;
- and
- a second rib of a third refractive index greater than said second refractive index formed on said first rib and longitudinally extending along a medial surface portion thereof, said second rib having a varying width in a first portion and a substantially constant width in a second portion.
A tapered single-mode rib waveguide, comprising:
- a substrate of a first refractive index;
- a layer formed on said substrate and having a second refractive index greater than said first refractive index;
- a first rib of said second refractive index formed on said layer and longitudinally extending along a surface thereof;
- and
- a second rib of a third refractive index greater than said second refractive index formed on said first rib and longitudinally extending along a medial surface portion thereof, said second rib having a varying width in a first portion and a substantially constant width in a second portion.
A tapered single-mode rib waveguide, comprising:
- a substrate of a first refractive index;
- a first rib of a second refractive index greater than said first refractive index formed on said substrate and longitudinally extending along a surface thereof;
- and
- a second rib of a third refractive index formed on said first rib and longitudinally extending along a medial surface portion thereof, said second rib having a varying width in a first portion and a substantially constant width in a second portion;
- wherein said first rib has a varying width in a portion adjacent said first portion of said second rib.
Dependencies are inferred from the claim text.