Dual-comb spectroscopy for in-plane angle measurement using OAM vortex light

By combining dual-comb spectroscopy and optical vortices, which have the orbital angular momentum (OAM) of light, we propose a novel measurement concept, "dual-vortex-comb spectroscopy (DVCS)." We extend the dual-comb spectroscopy to angle dimensions by utilizing the characteristic helical phase structure of optical vortices. We demonstrate a proof-of-principle experiment on DVCS that realizes in-plane azimuth-angle measurements with an accuracy of similar to 0.1 mrad after cyclic error correction, whose origin is verified by a simulation. We also demonstrate that the measurable angle range is tailored by the topological number of the optical vortices. This is the first demonstration of dimensional conversion between the in-plane angle and dual-comb interferometric phase. This successful result can expand the applicability of optical frequency comb metrology to new dimensions. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement