High-Q magnetic toroidal dipole resonance in all-dielectric metasurfaces
Ying Zhang,
Lulu Wang,
Haoxuan He,
Hong Duan,
Jing Huang,
Chenggui Gao,
Shaojun You,
Lujun Huang,
Andrey E. Miroshnichenko,
Chaobiao Zhou
Affiliations
Ying Zhang
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Lulu Wang
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Haoxuan He
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Hong Duan
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Jing Huang
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Chenggui Gao
School of Physics and Electronic Science, Guizhou Education University, Guiyang 550025, China
Shaojun You
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
Lujun Huang
State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Sciences, East China Normal University, Shanghai 200241, China
Andrey E. Miroshnichenko
School of Engineering and Technology, University of New South Wales at Canberra, Northcott Drive, Canberra, Australian Capital Territory 2610, Australia
Chaobiao Zhou
School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China
High quality (Q) factor toroidal dipole (TD) resonances have played an increasingly important role in enhancing light–matter interactions. Interestingly, TDs share a similar far-field distribution as the conventional electric/magnetic dipoles but have distinct near-field profiles from them. While most reported works focused on the electric TD, magnetic TDs (MTDs), particularly high-Q MTD, have not been fully explored yet. Here, we successfully realized a high-Q MTD by effectively harnessing the ultrahigh Q-factor guided mode resonances supported in an all-dielectric metasurface, that is, changing the interspacing between silicon nanobar dimers. Other salient properties include the stable resonance wavelength but a precisely tailored Q-factor by interspacing distance. A multipole decomposition analysis indicates that this mode is dominated by the MTD, where the electric fields are mainly confined within the dielectric nanostructures, while the induced magnetic dipole loops are connected head-to-tail. Finally, we experimentally demonstrated such high-Q MTD resonance by fabricating a series of silicon metasurfaces and measuring their transmission spectra. The MTD resonance is characterized by a sharp Fano resonance in the transmission spectrum. The maximum measured Q-factor is up to 5079. Our results provide useful guidance for realizing high-Q MTD and may find exciting applications in boosting light–matter interactions.
