Magnetic and electric response of single subwavelength holes

We use polarization-resolved near-field measurements, in conjunction with electromagnetic theory, to separate and quantify the electric and magnetic optical response of subwavelength holes in thick gold films. Using 1550 nm light, we determine the amplitudes of the electric and magnetic polarizabilities of holes with diameters ranging from 600 to 1000 nm. Additionally, we study the scattered field distributions that arise from the interactions of the holes with surface plasmon polaritons, and show that forward-backward scattering ratios as high as 2.5 : 1 are possible. Our study provides experimental access and theoretical understanding of the full electromagnetic polarizability that describes the optical response of metallic holes at telecom wavelengths, which is a prototypical structure in currently explored optical signal processing and sensing devices.