Optical Device Including a Buried Grating With Air Filled Voids and Method For Realising It
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Accused Products
Abstract
An optical device includes a waveguide, the waveguide having a core surrounded by a cladding, the cladding including a lower cladding, the core being placed above the lower cladding, a lateral cladding adjacent to a first and a second opposite lateral sides of the core, and an over-cladding, the over-cladding being positioned above the core and lateral cladding. The core and lateral cladding define a guiding layer. A grating structure is formed in the guiding layer, which includes a plurality of empty trenches. The over-cladding includes a cap layer, the cap layer having a first refractive index and being in contact with the grating structure. The first refractive index of the cap layer is substantially identical to the refractive index of the lateral cladding in contact with the cap layer. Additionally, the cap layer is located above the trenches and forms bridges connecting each couple of adjacent trenches of the plurality, so that voids are formed in the trenches.
49 Citations
78 Claims
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1-39. -39. (canceled)
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40. An optical device comprising a waveguide, said waveguide comprising
a core surrounded by a cladding, said cladding comprising a lower cladding, the core being placed above the lower cladding, a lateral cladding adjacent to a first and a second opposite lateral sides of the core, and an over-cladding, said over-cladding being positioned above said core and lateral cladding, wherein said core and lateral cladding define a guiding layer and said over-cladding comprises a cap layer, said cap layer having a first refractive index; - and
a grating structure formed in said guiding layer, said grating structure comprising a plurality of empty trenches, and said cap layer being in contact with said grating structure, wherein said first refractive index of said cap layer is substantially identical to the refractive index of the lateral cladding in contact with said cap layer, said cap layer being located above said trenches and forming bridges connecting each couple of adjacent trenches of said plurality so that the material forming said cap layer does not enter into said trenches. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A method for making a waveguide on a substrate, comprising the steps of:
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depositing a lower cladding layer on said substrate; forming at least one core over said lower cladding layer; depositing a lateral cladding layer over said core and/or over said lower cladding layer, wherein said lateral cladding and said core form a guiding layer; forming a plurality of empty trenches in said guiding layer; and depositing in a process chamber a cap layer on top of said plurality of empty trenches using a plasma chemical vapour apparatus, said deposition step comprising the substeps of; introducing a silicon source into the process chamber; and selecting the power to form the plasma and the depositing pressure in such a way that the material forming said cap layer is inhibited from filling said trenches. - View Dependent Claims (62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
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Specification