Waveguide-based bragg gratings with spectral sidelobe suppression and method thereof
First Claim
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1. An apparatus, comprising:
- a substrate; and
a plurality of regions formed in the substrate, the plurality of regions having refractive indices different from that of the substrate, the plurality of regions and intervening areas of the substrate forming a grating, the grating having a plurality of grating periods with substantially constant pitch, wherein each grating period of the plurality of grating periods includes a region of the plurality of regions, the plurality of regions having regions of at least two different widths.
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Abstract
A waveguide Bragg grating (WBG) is apodized by varying the duty cycle of selected grating periods while fixing the pitch of the grating periods. In one embodiment, the WBG is implemented in a silicon substrate using polysilicon filled trenches of varying width while keeping the grating periods'"'"' pitch constant. The polysilicon trenches are formed so that if the width of one trench is increased compared to an adjacent grating period, the trench width in the other adjacent grating period (if present) is decreased.
60 Citations
30 Claims
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1. An apparatus, comprising:
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a substrate; and
a plurality of regions formed in the substrate, the plurality of regions having refractive indices different from that of the substrate, the plurality of regions and intervening areas of the substrate forming a grating, the grating having a plurality of grating periods with substantially constant pitch, wherein each grating period of the plurality of grating periods includes a region of the plurality of regions, the plurality of regions having regions of at least two different widths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16)
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12. A method, comprising:
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providing a substrate with a buried layer having a refractive index less than that of the substrate;
forming, in the substrate and proximate the buried layer, a plurality of trenches of at least two widths, the plurality of trenches and intervening areas of the substrate forming a grating with a plurality of grating periods of constant pitch, each grating period including an associated trench of the plurality of trenches;
filling the plurality of trenches with a material having a refractive index different from that of the substrate and greater than that of the buried layer; and
forming a second layer on the substrate and plurality of filled trenches, the second layer having a refractive index less than those of the substrate and the material of the plurality of filled trenches.
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17. A system comprising:
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an optical signal source;
an optical fiber having one end coupled to the optical signal source; and
an integrated circuit that includes;
a substrate, and a plurality of regions formed in the substrate and having refractive indices different from that of the substrate, the plurality of regions and intervening areas of the substrate forming a grating, the grating having a plurality of grating periods with substantially constant pitch, wherein each grating period of the plurality of grating periods includes a region of the plurality of regions, the plurality of regions having regions of at least two different widths. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method, comprising:
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propagating an optical beam through a Xth region of a plurality of regions, the Xth region having a first width, wherein the plurality of regions are formed in a substrate, the substrate having a refractive index different from the refractive indices of the plurality of regions, and wherein the plurality of regions and intervening areas of the substrate form a grating, the grating having a plurality of grating periods of substantially constant pitch, each grating period of the plurality of grating periods including a region of the plurality of regions, the Xth region being contained in a Xth grating period of the plurality of grating periods; and
propagating the optical beam through a Yth region of the plurality of regions, the Yth region having a second width different from the first width and contained in a Yth grating period of the plurality of grating periods, the Yth grating period being adjacent to the Xth grating period. - View Dependent Claims (29, 30)
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Specification