Performance investigation of incident bandwidth based on reflective two-layer grating with high efficiency

Abstract

A novel reflective two-layer grating is proposed to obtain broad incident wavelength and angular bandwidths with the polarization-independent property. Although the conventional reflective single-layer grating can diffract high efficiency into the—1st order based on the mixed metal dielectric structure, deviations of the incident wavelength and angle will introduce much influence on the efficiency. By the reflective two-layer grating, the incident bandwidth can be improved greatly with high efficiency. The reflective two-layer grating can diffract efficiencies more than 90% into the—1st order within the incident wavelength range of 1376–1675 nm or the incident angular bandwidth of 33.05–51.21°. The presented reflective two-layer grating can have advantages of high efficiency and improved bandwidths. The given quite moderate fabrication tolerance should be significant for practical applications of such a reflective two-layer grating. • A reflective two-layer grating is presented for both TE and TM polarizations. • Incident bandwidths are improved greatly compared with the single-layer grating. • Moderate fabrication tolerance can make it significant for practical applications.