Magneto-optical characteristics of Au-Ni metasurface 1. . Gold d - PowerPoint PPT Presentation

Magneto-optical characteristics of Au-Ni metasurface 1. . Gold d ring g stru ructure cture One ring structure • Double ring structure • The design optimization • 2. . Hybrid Au-Ni Ni ring ng stru ruct cture re The design optimization • Magneto-optical characteristics • Kater eryna yna Domina na

1. G Gold ld ring structure ucture One ring structure EM-wave normal incident D=300nm r in vacuum r out h ring =60nm Au r in =40nm r out =60nm 1,0 2 |T| 0,8 2 |R| 0,6 2 2 &|T| |R| 0,4 0,2 0,0 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 Wavelength,  m

Double gold ring structure Au h spacer =50nm r in h ring =20nm r in =40nm r out D[nm] r out =60nm ɛ SiO 2 =2.1 250nm SiO 2

Double gold ring structure Current density distribution at resonances Symmetrical mode Asymmetrical mode

2 Au rings on Silica substrate (varying spacer height) Au h ring =20nm h spacer ɛ SiO 2 =2.1 250nm SiO 2 D=300nm r in r out r in =40nm r out =60nm 5

2 Au rings on Silica substrate (varying ring height) Au h spacer =50nm h ring 250nm SiO 2 ɛ SiO 2 =2.1 D=300nm r in r in =40nm r out r out =60nm 6

2 Au rings on Silica substrate (varying delta) Au h spacer =50nm h ring =30nm ɛ SiO 2 =2.1 250nm SiO 2 D=300nm r in =60-delta [nm] r in r out r out =60+delta [nm] 7

2. H Hybri rid Au-Ni Ni ring g structure ucture h spacer =40nm r in h ring =50nm r in =40nm r out D=300nm r out =60nm ɛ SiO 2 =2.1 250nm SiO 2

Current density distribution at resonances Ni upper+Au bottom λ =0,78µm λ =0,46µm 1 2 Au upper+Ni bottom λ =0,74µm λ =0,46µm

One Ni ring per period r in r in =40nm r out Ni h ring =20nm D[nm] r out =60nm 250nm SiO 2 Kerr rotation for 500 nm Ni film 10

Ni upper+Au bottom h ring =60nm h spacer =40nm r in =40nm r out =60nm MOKE Faraday effect D=300nm Optimized design of hybrid Au-Ni structure provides excitation of asymmetrical mode resonance in the optical range • obtaining Kerr rotation of ring structure with a filling factor ≈7% • comparable to Kerr rotation of bulk Ni changing the direction of polarization rotation without changing the • direction of magnitization