“…To enhance the extinction ratio further, increase in the Al grating thickness is effective, since it reduces the TE transmittance. 12,16) Another reason for the TE transmission leakage may be the misalignment of the Al grating direction; i.e., the direction of the AR grating was not completely parallel to the wire direction in the current sample. Therefore, we have to consider the effect of the structured birefringence; i.e., as this AR grating acted as a wave plate, TE polarization might have been transmitted slightly.…”