Patent ID: 7099549

Claim:
A semiconductor resonator structure comprising: a light transmissive substrate; a guiding channel defined in the substrate; and at least two distributed gratings defined in the substrate surrounding the guiding channel by at least two opposing sides of the guiding channel, wherein either the period of each of the gratings or their refractive index or both are not constant, wherein the gratings have an index profile given by n(ρ)=n eq (ρ) R/ρ and n eq (ρ=R exp(U/R)) has a conventional Bragg grating index profile, where ρ is the radial polar coordinate, n(ρ) is the real index of refraction as a function of ρ, n eq (ρ) is the equivalent index of refraction as a function of ρ, U is a transformational coordinate given by ρ=R exp (U/R), and R is an arbitrary constant.