Cascaded HfO₂/SiO₂ microstructure for symmetrical two-port beam dispersion

A new type of double-dielectric layer two-port beam splitter grating based on sandwich structure is proposed. This grating has the characteristic of zeroth order elimination. The structural parameters of the grating are optimized by the rigorous coupled-wave analysis (RCWA) and simulated annealing algorithm (SAA) to achieve the best performance of the grating. For both TE and TM polarizations, the diffraction efficiencies of & PLUSMN;1st orders can reach 49.34% and 49.15%, respectively. Meanwhile, the efficiency of the zeroth order is about only 0.5% for both polarizations. This novel microstructure has the significant characteristic of zeroth order elimination. Moreover, this grating has a wide incident bandwidth and excellent manufacturing tolerance. The simplified modal method (SMM) is also used to study the specific process of energy coupling in the grating.