Optical response to the linear and circular polarized light of the double-spirals structure

The optical response to the linear and circular polarized light of the double-spirals structures are investigated by the finite element simulation in this paper. For the linear polarized light the double-spirals structures are like a linear polarizer in the long wavelength region with the wavelength of 900–1500 nm, which corresponds to the standing-wave mode of a single spiral. The double-spirals structures have evident chiral effect in the long wavelength, and has 3–4 circular dichroism (CD) peaks in the wavelength range 850–1500 nm. For all structures investigated in this paper, the CD spectra have obvious blue shift with the increase of the arm width. The simulation results also indicate that the smaller the distance between the two spirals, the more the chiral effect of the double-spirals structures. The chiral effect for both structures with the distance of 400 nm diminishes, and both structures no longer have typical CD spectra.