Boosting the coupling efficiency in single-mode micro-structured fibers using Laguerre-Gaussian beams

Abstract

We propose a novel technique to boost the coupling efficiency of single-mode micro-structured fibers by tailoring the shape of the beam at the input. We show that by coupling programmable Laguerre-Gaussian (LG) beams into a single-mode micro-structured fiber, the optical throughput can be modulated with the topological charge of the LG beam. Phase holograms are encoded into a phase-only programmable spatial light modulator to produce LG beams at the Fourier plane of the coupling lens. For certain topological charges, the intensity of the guided light at the output end of the fiber can be greater than the intensity obtained by coupling a focused TEM₀₀ beam. For the solid-core micro-structured fiber used in the experiment, the output intensity for a coupled LG beam with topological charge, l = 16, is 7.5% greater compared to that of a focused TEM₀₀ beam.