1460731699-9f865201-33ce-40d6-98fd-89aa2d2ec738

1. An optical device, comprising:
a substrate;
a first cladding disposed on the substrate;
a first optical waveguide extended in a first direction on the first cladding, and having a first refractive index;
a side grating formed in at least one side of the first optical waveguide;
a second optical waveguide filling a space of the side grating, extended in a second direction across the first direction on the first cladding, and having a second refractive index; and
a second cladding disposed on the second optical waveguide, and having a third refractive index,
wherein the first refractive index is greater than the second refractive index, and the second refractive index is greater than the third refractive index.
2. The optical device of claim 1, wherein the second optical waveguide is extended onto the first optical waveguide, and the second cladding is disposed on the extended second optical waveguide.
3. The optical device of claim 1, wherein the second cladding is disposed to contact the first optical waveguide.
4. The optical device of claim 1, wherein the second optical waveguide is a silicon nitride layer or a silicon oxide nitride layer.
5. The optical device of claim 1, wherein the first cladding andor the second cladding are a silicon oxide layer.
6. The optical device of claim 1, wherein the second optical waveguide comprises:
a first taper region;
a straight line region; and
a second taper region,
wherein a size of the first taper region is greater than a size of the straight line region, and the size of the straight line region is greater than a size of the second taper region.
7. The optical device of claim 1, further comprising a third optical waveguide spaced apart from the first optical waveguide,
wherein the third optical waveguide contacts the second optical waveguide, and the second cladding is disposed on a portion of the third optical waveguide or over the third optical waveguide.
8. The optical device of claim 1, wherein the side grating is symmetrically disposed in both side surfaces of the first optical waveguide.
9. The optical device of claim 1, wherein the side grating comprises:
a first side grating disposed in a one side of the first optical waveguide; and
a second side grating disposed in other side of the first optical waveguide,
wherein the first and second side gratings are offset by each other within a range of period.
10. The optical device of claim 1, wherein the side grating is disposed in only a one side of the first optical waveguide.
11. The optical device of claim 1, wherein the side grating is slopingly disposed in a one side of the first optical waveguide.
12. The optical device of claim 1, further comprising a fourth optical waveguide disposed on a vertical grating formed in the second optical waveguide,
wherein the fourth optical waveguide is an optical fiber.
13. The optical device of claim 1, wherein the first and second optical waveguides are disposed on the same plane.
14. An optical device, comprising:
a substrate;
a first cladding disposed on the substrate;
a first optical waveguide extended in a first direction on the first cladding, and having a first refractive index;
a first side grating formed in at least one side of the first optical waveguide;
a second side grating formed in at least one side of the first optical waveguide to be spaced apart from the first side grating;
a second optical waveguide filling a space of the first side grating, extended in a second direction across the first direction on the first cladding, and having a second refractive index;
a third optical waveguide filling a space of the second side grating, extended in the second direction across the first direction on the first cladding, and having a third refractive index; and
a second cladding disposed on the second and third optical waveguides, and having a fourth refractive index,
wherein the first refractive index is greater than the second and third refractive indexes, and the second and third refractive indexes are greater than the fourth refractive index.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A method for determining a combined motion estimate between digital images captured at different capture times, comprising:
using an electronic image capture device to capture at least two digital images of a scene at different capture times;
designating one of the digital images as a reference digital image, and the rest of the digital images to be non-reference digital images;
designating a plurality of image regions within the digital images, wherein each image region includes at least a subset of image pixels in the digital images;
determining a motion estimate for each image region by:
shifting the image regions within the non-reference digital images according to each of a plurality of spatial offsets relative to the image region within the reference digital image to determine a plurality of shifted image regions, wherein the spatial offsets include horizontal and vertical offset values, each of which correspond to an integer number of image pixels;
using a data processor to compute merit function values for each of the spatial offsets, wherein the merit function values are an indication of an amount of difference between the image region in the reference digital image and the shifted image regions in the non-reference digital images;
using a data processor to fit a fitting function having a predefined functional form to at least a subset of the computed merit function values, wherein the fitting function provides an estimated merit function value as a function of spatial offset; and
determining the motion estimate responsive to the fitting function;

determining the combined motion estimate by combining the motion estimates for the plurality of image regions, wherein the combined motion estimate is determined by forming a weighted combination of the motion estimates for the plurality of image regions, each motion estimate being weighted with a weighting coefficient, and wherein the weighting coefficient for each image region is determined responsive to the shape of the corresponding fitting function; and
storing an indication of the combined motion estimate in a processor-accessible memory.
2. The method according to claim 1 wherein the motion estimate for each image regions is a non-integer spatial offset corresponding substantially to a local minimum or local maximum of the corresponding fitting function.
3. The method according to claim 1 wherein the weighting coefficients for image regions where the corresponding fitting functions have steeper local minima are larger than the weighting coefficients for image regions where the corresponding fitting functions have shallower local minima.
4. The method according to claim 1 wherein the weighting coefficients for image regions where the corresponding fitting functions have larger second derivatives are larger than the weighting coefficients for image regions where the corresponding fitting functions have smaller second derivatives.
5. The method according to claim 1 wherein the fitting function has a parabolic functional form.
6. The method according to claim 1 wherein the digital images correspond to preview images captured using a digital still camera.
7. The method according to claim 1 wherein the digital images correspond to image frames of a digital video sequence.
8. The method according to claim 1 wherein the image region corresponds to a focus region identified by an auto-focus algorithm.
9. The method according to claim 1 wherein the image region corresponds to a detected face region within the captured digital images.
10. The method according to claim 1 wherein the image region corresponds to an image region having a high scene brightness level.
11. The method according to claim 1 wherein the image region corresponds to an image region having a high level of scene detail.
12. The method according to claim 1 wherein the image region corresponds to an image region where there is a large difference between the captured digital images.
13. The method according to claim 1 wherein the plurality of spatial offsets correspond to an array of horizontal and vertical offset values.
14. The method according to claim 1 wherein the plurality of spatial offsets are defined according to an iterative search strategy.
15. The method according to claim 1 wherein at least three digital images are captured, and wherein the spatial offsets used to shift the image regions within each of the non-reference digital images are scaled proportionally to a capture time difference between the reference digital image and the corresponding non-reference digital image.
16. The method according to claim 1 wherein merit function values are determined responsive to a mean absolute difference between pixel values for the image region in the reference digital image and corresponding pixel values for the shifted image regions in the non-reference digital images.
17. The method according to claim 1 wherein the motion estimate is an indication of the motion of an object within the scene.
18. The method according to claim 1 wherein combined motion estimates are determined for a plurality of different reference digital images captured at different times, and wherein the combined motion estimates for the different reference digital images are combined to determine a time-averaged motion estimate.
19. The method according to claim 18 wherein the time-averaged motion estimate is determined by forming a weighted combination of the combined motion estimates for the different reference digital images, each combined motion estimate being weighted with a weighting coefficient.
20. The method according to claim 19 wherein the weighting coefficients for more recent combined motion estimates are larger than the weighting coefficients for earlier combined motion estimates.
21. The method according to claim 20 wherein the number of combined motion estimates or the weighting coefficients for the combined motion estimates are determined responsive to a light level of the scene.
22. The method according to claim 1 wherein the combined motion estimate is adjusted as a function of a scene brightness value to compensate for the effects of image noise in the captured digital images.
23. The method according to claim 22 wherein the combined motion estimates are reduced for scene brightness values below a predefined threshold.
24. The method according to claim 1 further including:
determining one or more image capture settings responsive to the combined motion estimate; and
using the electronic image capture device to capture an archival image according to the determined image capture settings.
25. A method for determining a combined motion estimate between digital images captured at different capture times, comprising:
using an electronic image capture device to capture at least two digital images of a scene at different capture times;
designating one of the digital images as a reference digital image, and the rest of the digital images to be non-reference digital images;
designating a plurality of image regions within the digital images, wherein each image region includes at least a subset of image pixels in the digital images;
determining a motion estimate for each image region by:
shifting the image regions within the non-reference digital images according to each of a plurality of spatial offsets relative to the image region within the reference digital image to determine a plurality of shifted image regions, wherein the spatial offsets include horizontal and vertical offset values, each of which correspond to an integer number of image pixels;
using a data processor to compute merit function values for each of the spatial offsets, wherein the merit function values are an indication of an amount of difference between the image region in the reference digital image and the shifted image regions in the non-reference digital images;
using a data processor to determine a motion estimate responsive to the computed merit function values; and
using a data processor to determine a weighting coefficient associated with the motion estimate responsive to one or more statistics determined from the computed merit function values;