Two-dimensional grating metasurface for communication band under Littrow mounting

Abstract

Abstract For communication, it is important to reduce the polarization-independence loss, especially for the stereoscopic incidence. A two-dimensional (2D) grating with the cylindrical hole (CDH) array is presented. The grating structure can achieve polarization-independent, high-efficiency and broadband output at the (-1, 0) diffraction order in the communication band. The novel metasurface achieves a diffraction efficiency of over 98% for both TE and TM polarizations at the (-1, 0) diffraction order. In addition, the (0, 0) diffraction order is well suppressed, resulting in extinction ratio of 43.89 dB and 46.18 dB for TE and TM polarization, respectively. In particular, the diffraction efficiency of the structure at the (-1, 0) order of magnitude under two polarizations exceeds 90% in the 1533-1561 nm bandwidth, which is a significant improvement over recently reported 2D gratings of the same type. Furthermore, the proposed structure has good incidence angle bandwidth and fabrication process tolerance, which ensures stable and efficient output in applications and fabrication. These results enrich the research on 2D gratings in the field of communication bands, and the designed grating has great potential for applications in spectroscopy, grating measurement and interferometry.