Bifunctional dielectric grating enabling asymmetric optical transmission and polarization beam splitting

A bifunctional dielectric grating was numerically studied, for the first time, to simultaneously enable asymmetric optical transmission and polarization beam splitting under normal incidence. Demonstrated at optical communication dual bands of 1310 nm and 1550 nm, the asymmetry ratios of the grating acted as a polarization-independent optical diode (OD) reached 25.98 dB and 34.14 dB, and the extinction ratios of the grating functioned as a polarization beam splitter (PBS) achieved 19.32 dB and 26.15 dB, respectively. Both asymmetry ratios and extinction ratios were further evaluated across two 10 nm bandwidth windows (1310±5 nm and 1550±5 nm). The superior performance of bifunctional grating originated from Fabry–Pérot (F–P) resonance and guided-mode resonance (GMR). Additionally, a unidirectional transmission grating to generate orthogonally-polarized dual-wavelength beams was also presented. The proposed all-dielectric grating holds significant promise for optical communication and information processing due to its dual functionality, planar configuration, compelling performance and CMOS compatibility.