Optical integrated circuit having passively aligned fibers and method using same

Claim 1

In combination: an optical integrated circuit (OIC) comprising a substrate having a reference surface on its bottom side and a plurality of waveguides on its top side, said waveguides having central axes that reside in a plane that is positioned above the reference surface by an exact predetermined distance, the bottom side of the OIC having an alignment feature for fixing the lateral position of the waveguides; a fiber array comprising a substrate having a reference surface on its bottom side and a plurality of troughs containing optical fibers on its top side, said optical fibers having central axes that reside in a plane that is positioned above the reference surface by said exact predetermined distance, the bottom side of the fiber array having an alignment feature for fixing the lateral position of the optical fibers; and a first planar bridging structure having a reference surface on its top side that engages the reference surfaces of the OIC and the fiber array, and holds the waveguides and optical fibers in vertical alignment, the top side of said planar bridging structure having complementary alignment features that engage the alignment features of the OIC and the fiber array and hold them in lateral alignment.

Claim 20

A method for providing accurate passive alignment between an optical integrated circuit (OIC) and a fiber array, both mounted on a bridging structure, said OIC comprising a silicon substrate having a plurality of longitudinally extending optical waveguides deposited on a top side thereof, said fiber array comprising a silicon substrate having an equal plurality of optical fibers disposed in longitudinally extending troughs on a top side thereof, said bridging structure comprising a planar silicon substrate, the method including the following steps: forming an alignment feature on the bottom side of the OIC substrate that establishes the horizontal location of the optical waveguides to within 0.5 microns; forming a reference surface on the bottom side of the OIC substrate that is a first predetermined distance below a plane that passes through the central axes of the optical waveguides; forming an alignment feature on the bottom side of the fiber array substrate that establishes the horizontal location of the optical fibers to within 0.5 microns; forming a reference surface on the bottom side of the fiber array substrate that is a second predetermined distance below a plane that passes through the central axes of the optical fibers, said first and second predetermined distances being equal to each other within 0.5 microns; forming alignment features on a top side of the bridging structure substrate that are complementary to the alignment features on the bottom sides of the OIC and the fiber array substrates; selecting the optical fibers for disposition in the troughs of the fiber array having outside diameters that are equal to a predetermined diameter ±0.3 microns; and narrowing the selection of optical fibers to ones having an eccentricity which is less than 0.15 microns.

Claim 21

A method for providing accurate passive alignment between an optical integrated circuit (OIC) and a fiber array, both mounted on a bridging structure, said OIC comprising a silicon substrate having a plurality of longitudinally extending optical waveguides deposited on a top side thereof, said fiber array comprising a silicon substrate having an equal plurality of optical fibers disposed in longitudinally extending troughs on a top side thereof, said bridging structure comprising a planar silicon substrate, the method including the following steps: forming an alignment feature on the bottom side of the OIC substrate that establishes the horizontal location of the optical waveguides to within 0.5 microns; forming a reference surface on the bottom side of the OIC substrate that is a first predetermined distance below a plane that passes through the central axes of the optical waveguides; forming an alignment feature on the bottom side of the fiber array substrate that establishes the horizontal location of the optical fibers to within 0.5 microns; forming a reference surface on the bottom side of the fiber array substrate that is a second predetermined distance below a plane that passes through the central axes of the optical fibers, said first and second predetermined distances being equal to each other within 0.5 microns; forming alignment features on a top side of the bridging structure substrate that are complementary to the alignment features on the bottom sides of the OIC and the fiber array substrates; selecting the optical fibers for disposition in the troughs of the fiber array having outside diameters that are equal to a predetermined diameter ±0.3 microns; and narrowing the selection of optical fibers to ones having an eccentricity which is less than 0.15 microns.