Highly sensitive magnetic field sensor with normal-incidence geometry using Ni-based bilayer subwavelength periodic structure operating in visible-wavelength region

We successfully demonstrate a highly sensitive optical sensor for detecting magnetic fields with normal-incidence geometry that uses a Ni-based bilayer subwavelength periodic structure (SWS) operating in the visible-wavelength region. The electromagnetic field distribution within the SWS as calculated by the finite-difference time-domain method indicates that the bilayer SWS has the potential to detect minuscule magnetic fields without the need for a complex incidence system. Our bilayer Ni-SWS system with its very simple normal incidence geometry is experimentally able to detect magnetic field changes of the order of a few millitesla.

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