Patent ID: 7116878

Claim:
A planar waveguide structure comprising: a core layer having a first refractive index, n core , and no photonic band structure; and a cladding layer, said cladding layer having first and second opposing external surfaces, said first surface contiguous with a first surface of said core layer, the cladding layer comprising: a first region having a first refractive index, n cladding , where n core >n cladding ; and a plurality of sub-regions formed in said first region, said sub-regions having a second refractive index, n sub , the sub-regions arranged in an array in a plane, said plane parallel to said first surface, each sub-region extending from said second surface of said cladding layer in a direction perpendicular to said plane, wherein the array of sub-regions comprises a photonic band structure in a region of said cladding, for perturbing only an evanescent field of an optical signal propagating through the core layer wherein an effective mode index contrast experienced by the optical signal propagating adjacent the cladding photonic band structure region is greater than 0.1 percent.