Fig. 4
From: Dual-band polarized upconversion photoluminescence enhanced by resonant dielectric metasurfaces
a Upconversion luminescence spectra of UCNPs coupled to the resonant metasurface, recorded with a rotating analyzer at various angles from 0 to 180° in front of the spectrometer. b Upconversion emission spectra from UCNPs on a glass substrate, recorded at different detection polarization angles ranging from 0 to 180°. c–d Polar plots illustrating the luminescence intensity of UCNPs coupled to the metasurface c and UCNPs on a glass substrate d as functions of the emission polarization angle. e Degree of polarization (DoP) for upconversion luminescence of UCNPs on both metasurface and glass substrate