Figure 7: (a) Sketch of a microroll consisting of an (In)GaAs (red) and a gold layer (yellow). (b) Simulation setup: black lines indicate the simulation volume with periodic boundary conditions in the and direction. A plane wave is incident in direction with the magnetic field vector pointing along the tube axis; that means in the direction. (c) Simulated transmission spectra of microroll arrays with varying winding numbers and the calculated resonance frequencies . (d) Retrieved complex permeability of a microroll array for a winding number of . Figure reprinted from  with slight modifications.