Tailoring the spatial localization of bound state in the continuum in plasmonic-dielectric hybrid system

Abstract

Bound states in the continuum (BIC) are considered as an effective means to dramatically elongate the trapping time of light. However, light-matter interaction depends not only on the life-time of an optical mode, but also on its mode volume. Therefore, increasing the life-time of an optical mode and minimizing the mode volume simultaneously, utilizing the BIC resembles a promising way for enhancing light-matter interaction. Herein, we have proposed a novel hybrid plasmonic-dielectric structure to manipulate the mode volume of BIC. For the Friedrich-Wintgen BIC, the electric field is strongly confined in the dielectric nanoparticle, leading to the considerable field enhancement compared with the single dielectric nanoparticle case. In contrast, strong localization of electric field can be achieved along the surface normal direction for the symmetry-protected BIC, leading to one order of magnitude reduction of mode volume in one unit cell compared with the conventional symmetry-protected BIC of all-dielectric structure. The proposed hybrid photonic system could provide an ideal flat platform for advanced manipulation of light-matter interaction.

Keywords

• bound state in the continuum
• mie resonance
• nonlinear optical absorption
• surface plasmon polaritons
• dielectric-metal hybrid structure