Fig. 1: Schematic of the planar photonic chip and its photonic band gaps.
From: Planar photonic chips with tailored angular transmission for high-contrast-imaging devices
a The photonic chips composed of three parts, the bottom (29 pairs of SiO2 + SiNx in total), top multilayer (10 pairs of SiO2 + SiNx in total), and the scattering layer (doped with TiO2 nanoparticles). Under normal incidence of 640 or 750 nm wavelength light, evanescent waves or hollow cones of light can be generated at the top surface, respectively. b, c Calculated PBGs of the bottom and top multilayers. The color scale encodes the theoretical reflectivity of the bottom and top multilayer. The horizontal red-dashed lines represent the positions of the incident wavelengths, 640 and 750 nm. The vertical white-dashed lines represent the position of the TIR angle at glass/air interface (corresponding to NA = 1). The left parts of the b, c are of the TM-polarized incident beam and the right parts TE-polarized one, separated by the vertical black-dashed lines. d, e Calculated angular-dependent reflectivity of the bottom and top multilayers. The incident wavelengths are set as 640 and 750 nm. The incident polarization is of either TM (left part) or TE (right part). The insets on d, e simply presents the designed roles of the bottom and top multilayers. TM transverse magnetic, TE transverse electric.
