Polarization-independent highly-efficient splitter based on the cross-shaped ridge structure

A polarization-independent highly-efficient transmission beam splitter based on the cross-shaped ridge structure is proposed in this paper. Based on the rigorous coupled-wave analysis (RCWA) and the simulated annealing (SA) algorithm, the efficiencies of 32.33% of 0th order and 32.42% of ±1st order for transverse electric (TE) polarization and 32.53% of 0th order and 32.60% of ±1st order for transverse magnetic (TM) polarization can be achieved. In addition, the simplified modal method (SMM) is applied to analysis the internal energy changes process in detail. What is more, different from the reported references only considering the case of one layer, we also used the SMM to analyze the three-port cross-array beam splitter under normal incidence with the approximation treatment. The results show that the method of which has certain reference value, which can be the guidance of the design of the gratings with similar structures in the future.