Birefringent optical waveguide structure having a strip waveguide buried in a cladding layer and the method of manufacturing
First Claim
1. A birefringent optical waveguide structure comprising at least one strip waveguide of a first material being buried in a cladding layer of a second material, each strip waveguide having a longitudinal axis, said cladding layer with the strip waveguide being positioned between two additional layers, said first material having an index of refraction higher than the index of refraction of the second material and both of the additional layers applying a mechanical stress on the cladding layer and on each strip waveguide with a component of the stress extending perpendicular to the longitudinal axis of the waveguide.
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Abstract
A birefringent optical waveguide structure comprises at least one or more strip waveguides of a first material embedded in a cladding layer of a second glass with at least one additional layer being applied on the cladding layer. The strip waveguides have a refractive index which is higher than the refractive index of the second glass of the cladding layers and the additional layer applies a mechanical stress to the strip waveguides which has a component extending perpendicular to the strip waveguides. Preferably, the mechanical stress is formed by the material of the additional layers having a different thermal expansion coefficient and a different elasto-optical coefficient than the materials forming the cladding layer and the strip waveguides. The method of forming the device includes rapidly cooling the structure from an elevated temperature to room temperature to create the mechanical stresses.
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Citations
14 Claims
- 1. A birefringent optical waveguide structure comprising at least one strip waveguide of a first material being buried in a cladding layer of a second material, each strip waveguide having a longitudinal axis, said cladding layer with the strip waveguide being positioned between two additional layers, said first material having an index of refraction higher than the index of refraction of the second material and both of the additional layers applying a mechanical stress on the cladding layer and on each strip waveguide with a component of the stress extending perpendicular to the longitudinal axis of the waveguide.
- 4. A birefringent optical waveguide structure comprising at least one strip waveguide of a first material being buried in a cladding layer of a second material and at least one additional layer being provided on the cladding layer, each strip waveguide having a longitudinal axis, said first material having an index of refraction higher than the index of refraction of the second material and the additional layer applying a mechanical stress on each strip waveguide with a component of the stress extending perpendicular to the longitudinal axis of the waveguide, the first material and the second material being glass materials, the material of the additional layer being a glass material having a different coefficient of thermal expansion and a different elasto-optical coefficient in comparison to the glass materials of the strip waveguide and cladding layer.
- 6. A method of forming a birefringent optical waveguide structure having at least one strip waveguide of a first material buried in a cladding layer of a second material and at least one additional layer being provided on the cladding layer, each strip waveguide having a longitudinal axis, said first material having a refractive index higher than the refractive index of the second material and said additional layer applying a mechanical stress to each strip waveguide with a component of the stress extending perpendicular to the longitudinal axis of the waveguide, said method comprising the steps of providing a substrate with a cladding layer having at least one strip waveguide embedded therein and having an additional layer on the cladding layer to form a structure, heating the structure to a relatively high elevated temperature and then subjecting the structure to a rapid cooling to room temperature.
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