Impact of resonator rotational symmetry on infrared metamaterial absorber

We investigate the impact of rotational symmetry of the metamaterial perfect absorber on its performance. The calculated results show that a absorption peak appears at the same wavelength in the absorption spectrum no matter the polarization of the incident light parallels to x axis or y axis when the absorber possesses four-fold rotational symmetry. However, in the case of two-fold rotational symmetry, the absorption peak splits into two peaks when the polarization of the incident light parallels to x axis. The results of the absorption peak properties with different rotational symmetry may be helpful to design novel polarization-insensitive absorbers.