https://doi.org/10.1051/epjconf/202125504002
Efficient coupling of free propagating light into Whispering Gallery Modes
1 Istituto Italiano di Tecnologia, Via Morego 30, 16136 Genova, Italy
2 Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), via Campi Flegrei 34—Comprensorio A. Olivetti, 80078, Pozzuoli (Na), Italy
* e-mail: xavislow@protonmail.com
Published online: 18 November 2021
Whispering Gallery Mode resonators are dielectric structures with cylindrical symmetry. They are typically excited with an evanescent field leaking out of a tapered fiber or a waveguide. It is also known that they can be excited with free propagating beams. In this work, we use a recently developed analytical model which quantitatively describes the coupling of free propagating beams into Whispering Gallery Modes for spherical particles. Using this model, we have been able to theoretically quantify the mode purity and the coupling efficiency of a resonant Whispering Gallery Mode of an order j*= 1456. We have observed that the transverse position of the beam plays a crucial role in determining the mode purity and coupling efficiency. Last but not least, we have verified that the coupling efficiency as well as the Q-factor predicted by our model are in an outstanding agreement with the experimental values measured on a microresonator of the same dimensions as the simulated one.
© The Authors, published by EDP Sciences, 2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
