Patent ID: 8401345

Claim:
An integrated circuit, comprising: an optical waveguide defined in a semiconductor layer; an optical modulator, having a first end and a second end, disposed on the optical waveguide, wherein a given end, which can be one of the first end and the second end, has a cross-sectional area having a first value; and a first 3-dimensional (3-D) taper structure and a second 3-D taper structure that are, respectively, proximate to the first end and the second end, wherein at least one of the first and the second 3-D taper structure is disposed directly on the optical waveguide, wherein a height of the first 3-D taper structure and a height of the second 3-D taper structure proximate to the optical modulator approximately equal a height of the optical modulator, and wherein a cross-sectional area of a given 3-D taper structure, which can be one of the first 3-D taper structure and the second 3-D taper structure, increases from a second value distal to the given end to the first value proximate to the given end, thereby reducing optical-coupling loss by approximately matching a spatial extent of an optical mode in the optical waveguide and a spatial extent of an optical mode in the optical modulator.