Study On Magneto-optical Periodic Nano-structures

Magneto-optic effects are widely used in magneto-optical modulators,magneto-optical isolators,magneto-optical sensors etc..With the continuous development of nanotechnology,it has been found that the combination of magneto-optical materials and sub-wavelength microstructures can provide many novel features and functions.On the one hand,by adopting these structures,a new regulation way of the optical properties of the device by the magnetic field can be realized.On the other hand,the electromagnetic field enhancement caused by the resonance in the structure leads to a great improvement in the magneto-optical performance of the structure.Therefore,it is necessary to conduct in-depth research on the magneto-optical periodic nano-optical structure.Firstly,in this paper,the magneto-optical surface plasmon resonance device composed of magneto-optical materials and noble metal periodic nanostructures was studied.The current MOSPR devices mainly use magnetic metals,and the optical loss is high.Applied to the refractive index sensing,there is a problem that the device has a low figure-of-merit?FoM?.Aiming at this problem,this paper proposes a MOSPR sensor based on dielectric magneto-optical material.The dielectric magnetic material film is Ce doped yttrium iron garnet?Ce:YIG?.The Ce:YIG film material has a low optical loss in the visible to near-infrared wavelength range and shows strong magneto-optical effect.By constructing periodic Au nanodisk arrays,Ce:YIG film and TiN film triple layers structure,Au nanodisk's LSPR and TiN-Ce:YIG interface propagation surface plasmon resonance coupling can be realized,which can significantly reduce the scattering loss of LSPR and enhance the magneto-optical effect.The absolute value of the Transverse Magneto-Optical Kerr Effect?TMOKE?reaches0.21.The use of this device to prepare the sensor,using the strong magneto-optical effect of the magneto-optical oxide,can significantly improve the FOM of the LSPR sensor.Based on the TMOKE spectrum for sensing,the sensor's FOM is up to 2200RIU^-1,which is more than 20 times higher than traditional LSPR devices(?108 RIU^-1).At the same time,we have prepared,characterized and tested this device.Then,the all-dielectric magneto-optical periodic nano-optical structure was studied.Due to the dispersion absorption and energy loss of the metal material,it is difficult to achieve high Q resonance.Mie resonance based on high dielectric constant all-dielectric metamaterial can effectively solve this problem.In this paper,a large area hexagonal period YIG/Ce:YIG nanohole structure was obtained by lift-off process using polystyrene nanosphere lithography and pulsed laser deposition.The structure period is1?m,and the nanohole diameter is 600 to 800 nm.The transmission spectrum of the all-dielectric grating structure exhibits obvious electrical resonance and magnetic resonance peak compared with the continuous film.This structure has enhanced magneto-optical effect and has potential applications in devices such as optical isolators and magneto-optical sensors.