Fig. 1. Schematic of the encapsulated metal-dielectric grating configuration for two-port beam splitters.

Fig. 2. Theoretical grating efficiency as a function of two unified parameters, grating period P and groove depth D under (a) TE polarization, (b) TM polarization, and (c) the minimum of the ηTE and ηTM at each point.

Fig. 3. Partially enlarged contour of the part in the white rectangle in Fig. 2(c) with grating efficiencies over 46%.

Fig. 4. Grating efficiency of the encapsulated metal-dielectric reflective grating as a function of the incident wavelengths for two crossed polarizations, where “TEd” and “TMd” denote results for TE and TM polarizations calculated by the strict numerical calculation method, respectively, and the “TE” and “TM” are results obtained by the unified design method.