Patent ID: RE41570

Claim:
An optical apparatus comprising: a slab optical waveguide substantially confining in one transverse dimension optical signals propagating in two dimensions therein; and a set of diffractive elements collectively arranged within the slab waveguide so as to exhibit a positional variation in amplitude, optical separation, or spatial phase over some portion of the set, wherein: the diffractive elements of the set are collectively arranged so as to apply a transfer function to an input optical signal incident on the diffractive element set to produce an output optical signal, the transfer function being determined at least in part by said positional variation in amplitude, optical separation, or spatial phase exhibited by the diffractive elements of the set; and the slab waveguide and the diffractive element set are arranged so as to substantially confine only one of the input and output optical signals to propagate in the slab waveguide so that the optical signal thus confined is successively incident on the diffractive elements of the set, while the other of the input and output optical signals propagates substantially unconfined by the slab waveguide in a direction having a substantial component along the confined dimension of the slab waveguide.