Patent ID: 9103975
Filing Date: 2015-08-11
Classification: G02B

Abstract:
1. A method of generating electromagnetic radiation carrying orbital angular momentum (OAM), the method comprising placing an electromagnetic wave in a resonator having a closed-loop waveguide supporting a guided wave propagating at resonance with angular order, p, and with an angular grating patterned in the closed-loop waveguide, the angular grating having a integer number, q, of grating elements, wherein the angular grating selectively couples the guided wave mode to a free space radiation mode having an OAM quantity, l, and out-of-plane wave vector component, k rad,z , and wherein significant coupling to the grating occurs only when the following wave matching condition is satisfied: where: m is the diffraction order of the angular grating, m=1, 2, 3, . . . ,.