A device is provided. The device includes a waveguide configured to output a first light having a first polarization to a first side of the waveguide and a second light having the first polarization to a second side of the waveguide. The device also includes an optical element assembly disposed at the first side of the waveguide and configured to convert the first light having the first polarization into a third light having a second polarization, and output the third light toward the waveguide. The device further includes a polarizer disposed at the second side of the waveguide and configured to transmit the third light having the second polarization, and block the second light having the first polarization.