Patent ID: 8854624

Claim:
An apparatus comprising: an optical waveguide configured to support propagating optical energy in a first direction; a photonic crystal comprising a dielectric material, the photonic crystal located on an exterior surface of the optical waveguide; wherein the photonic crystal comprises a first surface including a first array of periodic features on or within the dielectric material, the array extending in at least two dimensions and including an effective dielectric permittivity different from the surrounding dielectric material; and wherein the periodic features include a specified lattice constant, the periodic features configured to extract a desired portion of the propagating optical energy from the waveguide through the photonic crystal via outcoupling the desired portion of propagating optical energy from a waveguided mode established by the waveguide to a weakly-coupled leaky mode established by the photonic crystal, the desired portion determined at least in part by the specified lattice constant, and the outcoupling occurring in a direction having a component orthogonal to the waveguided propagation in the first direction.