Ultranarrow perfect absorber with linewidth down to 1 nm based on optical anapole mode.

• This paper is investigated a silicon-dielectric-metal nanostructure, it supports the optional anapole mode due to the destructive interference between electric and toroidal dipoles. • Such the proposed nanostructure exhibits a near-perfect ultra-narrow absorption spectrum in the near infrared region with the absorption bandwidth of 0.48 nm and a high-quality factor up to 1763. In addition, the structure we designed has both excellent sensing performance and field enhancement performance, which can be used to design multi-function chips. • Our design is a simple flat structure, which is easy to process and manufacture in actual production. This paper is investigated a silicon-dielectric-metal nanostructure, it supports the optional anapole mode due to the destructive interference between electric and toroidal dipoles. Such the proposed nanostructure exhibits a near-perfect ultra-narrow absorption spectrum in the near infrared region with the absorption bandwidth (FWHM) of 0.48 nm and a high-quality (Q) factor up to 1763. Besides inherently low dissipative losses and strong anapole response, this optical nanostructure can demonstrate subtle refractive index sensing properties. Our work shed new light on active ultra-narrow band perfect absorption based on the optical anapole mode, and provides potential applications such as optical sensors, narrow-band filter, non-radiative data transmission and biomolecules manipulation. [ABSTRACT FROM AUTHOR]