Double-sided structure grating for dual-functional polarizing or non-polarizing splitter

Abstract

In this paper, a novel bidirectional dual-functional metal-dielectric reflective grating with a double-sided structure is described, which can achieve transverse-electric (TE) polarization in the -1st order and transverse-magnetic (TM) polarization in the 0th order as a polarizing beam splitter in the upper part of the grating or TE and TM polarizations in the -1st order with polarization-independent property in the lower part of the grating. The proposed grating works at wavelength 1550 nm under Littrow mounting. Rigorous coupled-wave analysis (RCWA) is used to optimize grating parameters. The upper part can achieve diffraction efficiencies of 99.53% and 99.11% for TE polarization in the -1st order and TM polarization in the 0th order, respectively. In addition, the extinction ratios of -1st order and 0th order are 58.87 dB and 52.02 dB, respectively. The lower part can achieve diffraction efficiencies of 99.41% and 99.26% for TE and TM polarizations in the -1st order, respectively. Furthermore, wide incident wavelength and angular bandwidths can be obtained in both the upper and lower parts. Such a high-efficiency dual-functional grating has a wide range of applications in optical systems.