Patent ID: 8189972

Claim:
An optical coupler, comprising: a first waveguide configured to supply a first optical signal having a wavelength, the first optical signal having a first mode; and a second waveguide, wherein the first waveguide has a tapered portion, the tapered portion being spaced from the second waveguide by a distance sufficient to facilitate evanescent coupling of the first optical signal from the first waveguide to the second waveguide, a first effective refractive index of the first waveguide at a location in the tapered portion being equal to a second effective refractive index at a location in the second waveguide, the first effective refractive index being associated with the first mode and the second effective refractive index being associated with a second mode of a second optical signal having the wavelength, the second mode being different than the first mode, and the second waveguide being configured to supply the second optical signal, the first waveguide being laterally spaced from the second waveguide.