Higher-order anapole-exciton strong coupling in nested Si-based hybrid systems

Higher-order anapoles have wide prospects in nonlinear optics and nanolasers due to their narrow resonances and strong energy localization. However, strong coupling involving higher-order anapoles has not been explored yet. In this work, we theoretically propose two Si-based hybrid systems consisting of a nested nanodisk-ring of Si and WSe2 to acquire strong coupling of higher-order anapoles with excitons. By tuning the structural parameters of the hybrid system with a Si nanoring inserted with a WSe2 nanodisk, the excited first-, second-, and third-order anapoles of the hybrid system all strongly couple with the excitons of the WSe2 nanodisk, leading to large Rabi splittings of 83.92, 90.95, and 78.53 meV, respectively. Furthermore, strong coupling behaviors of the excited first- and second-order anapoles of the hybrid system with the excitons of the WSe2 nanoring are also achieved in the hybrid system with a Si nanodisk surrounded by a WSe2 nanoring, with corresponding Rabi splittings of 191.3 and 189.1 meV. Our work opens a new direction for the research on higher-order anapoles and provides a promising outlook for high-performance strong coupling devices.