  In this paper, we propose a plasmon-induced transparency (PIT) metamaterial
structure composed of Ag nanomaterials with polarization sensitivity. The
metamaterial model consists of three bright modes with different resonant
frequencies. The optical properties of the structure are further investigated
using finite difference time domain (FDTD) method. The results show that the
conversion between single-band PIT and dual-band PIT effects can be achieved by
changing the polarization degree of the incident light, the number of
transparent windows can be changed from one to two, and the process is
accompanied by the conversion of bright and dark modes and the change of the
resonance wavelength of the transmission peak. In addition, When the light is
polarized in the Y-direction, the two transparency windows have different
refractive index sensitivities, with FOM values of 5.94/RIU and 5.65/RIU,
respectively.
