I-shaped Stack Configuration for Multi-Purpose Splitter

In this paper, a high-efficiency beam splitter based on an I-shaped stack configuration under normal incidence is proposed, which can function as a multi-functional polarization-independent and a bi-functional polarizationselective beam splitter at the wavelength of 1550 nm. The rigorous coupled-wave analysis and a simulated annealing algorithm are used in the process of calculating and optimizing. When the grating functions as a polarization-independent beam splitter, the diffraction efficiency of each main diffraction order can be greater than 48%, 32%, 24%, and 19% of dual- to five-port output for transverse electric (TE) and transverse magnetic (TM) polarizations respectively. When the grating is employed as a polarization-selective beam splitter, the total efficiencies exceed 95% for TE and TM polarizations as well. Furthermore, this research applies a simplified modal method to reveal the energy distribution inside the grating. Compared to previously reported beam splitters, the proposed grating structure has higher efficiency and uniformity, making it well-suited to the various output mode requirements of large-scale optical communication systems.