Patent ID: 7245803

Claim:
An integrated optical apparatus, comprising: a planar waveguide having an elongate guiding portion and a grating coupler, said coupler having at least a flared waveguide portion comprising a relatively narrow end portion and a relatively wide end portion, said flared portion comprising upper and lower surfaces and at least one curved sidewall for guiding the propagation of light in said flared portion between said relatively wide end portion and said relatively narrow end portion, said curved sidewall having a curvature defined by a substantially hyperbolic path, wherein said flared portion has a grating positioned to couple light between said coupler and an optical element that is located above said planar waveguide by directing light into or out of said upper or lower surfaces of said flared portion, said light in said flared portions comprising curved wavefronts, said grating comprising a plurality of curved elongate scattering elements having curvatures that are different than the curvatures of wavefronts of said light propagating in said flared portion and scattered by said curved elongate scattering elements.