We theoretically demonstrate a long-period grating (LPG) based single-mode fiber to multi-core fiber coupler. The coupling efficiency achieved was 24% of the input power, evenly distributed by all cores, using LPGs of length 4 cm.

Agradecimentos: The authors would like to thank grant 15/24494-8 from São Paulo Research Foundation (FAPESP), CNPq as well as the European Union's Horizon 2020 project under grant agreement no 688941 (FUTEBOL), the MCTI through RNP and the grant 151554/2018-8 CNPq, for the financial support