A slab optical waveguide confines in one transverse dimension optical signals propagating in two dimensions therein, and has a set of diffractive elements collectively arranged so as to exhibit positional variation in amplitude, optical separation, or spatial phase. The diffractive elements are collectively...http://www.google.de/patents/US20070019910?utm_source=gb-gplus-sharePatent US20070019910 - Distributed optical structures in a planar waveguide coupling in-plane and out-of-plane optical signals
