Low loss lateral optical waveguide intersections
A geometrically shaped optical waveguide crossing or intersection with minimal transmission loss is described. A symmetrically tapered waveguide intersection is used to minimize loss in the intersecting region where at least two optical waveguides cross one another at 90° or nearly 90°. The present invention embodies a waveguide crossing that includes tapering the width of the waveguides as they approach the intersecting region, forcing the propagating light to contract, thereby reducing asymmetric field distortions, and thus reducing transmission loss and effectively minimizing crosstalk. This is accomplished by focusing the propagating light through a perpendicular or near perpendicular in at least two waveguide intersection by simple linear tapering rather than by the use of a lens or other previously used devices.
1. An optical device comprising:
a first waveguide extending in a first direction; and
a second waveguide extending in a second direction substantially perpendicular to the first direction, the first and second waveguides intersecting at an intersection region, a first portion of the first waveguide being spaced from the intersection region,
wherein a width of the first waveguide narrows from the first portion of the first waveguide toward the intersection region, such that the first waveguide modifies a phase front of an optical beam which propagates along the first waveguide from the first portion of the first waveguide toward the intersection region.
2. The optical device of claim 1 , wherein the modified phase front has a parabolic shape.
3. The optical device of claim 1 further comprising a second portion of the first waveguide being spaced from the intersection region, the first and second portions of the first waveguide being positioned on opposing sides of the intersection region,
wherein a width of the first waveguide narrows from the second portion of the first waveguide to the intersection region.
4. The optical device of claim 3 , wherein a first portion of the second waveguide is spaced apart from the intersection region and a second portion of the second waveguide is spaced apart from the intersection region, the first and second portions of the second waveguide being positioned on opposing sides of the intersection region,
wherein a width of the second waveguide narrows from the first portion of the second waveguide to the intersection region and the width of the second waveguide narrows from the second portion of the second waveguide to the intersection region.
5. The optical device of claim 1 , further comprising a third waveguide extending in a third direction substantially perpendicular to the first and second direction, the third waveguide intersecting the first and second waveguides at the intersection region.
6. The optical device of claim 1 , wherein the first portion of the first waveguide is spaced a distance of approximately 3 microns from the intersection region.
7. The optical device of claim 1 , wherein the first portion of the first waveguide is spaced a distance of no more than approximately 3 microns from the intersection region.
8. The optical device of claim 1 , wherein the phase front of the optical beam is substantially perpendicular to a longitudinal axis of the first waveguide at a location within the intersection region as the optical beam propagates through the intersection region.