A significant enhancement of the longitudinal magneto-optical effect is demonstrated numerically and experimentally in transmission, and for small angles of incidence, through a subwavelength resonant structure consisting of a dielectric grating on top of a magneto-optical waveguide. The enhanced polarization rotation is associated with a high transmittance. These low footprint devices may thus be suitable for applications like magnetic field sensors or in non-destructive testing.

The enhancement of magneto-optical (MO) effects in planar devices is commonly obtained through the combination of a plasmonic resonance and a MO material, or through the microstructuration of such materials. However, the devices often suffer from weak optical signal, or require fastidious lithography processes. We present a much simpler device made of a photoresist 1D grating processed on a MO composite planar waveguide. This latter is formed by magnetic nanoparticles embedded in a silica matrix. Such all-dielectric device produces much higher Q-factor resonances, which finally result in giant MO intensity effects. Their magnitude combined with the ability of the device to be processed on large scale and various substrates, are very promising for a wide range of sensing applications.

No abstract

No abstract