Double-step five-port grating with polarization independence

This paper proposes a five-port grating under normal incidence at an incident wavelength of 800 nm. The grating is a two-step layered structure composed of fused silica and Ta2O5. Especially, compared with a conventional single-groove five-port grating for only one polarization, such a novel microstructure can simultaneously meet the transverse electric (TE)/transverse magnetic (TM) polarization requirements. Most importantly, the grating has good polarization-independent splitting performance. The data shows that grating structure has high process tolerance, which will have merits in the field of beam splitter. The proposed double-step five-port grating can be potentially applied in multichannel interferometers with the new polarization-independent property.