Fig. 3
Meta-optics for SPDC. a Top: schematic of SPDC in a LiNbO3 thin film. Bottom: the frequency spectrum measured using the single-photon spectroscopy method. The red curve is the calculated frequency spectrum and the blue dots are the values of second-order correlation as a function of the delay time [83]. b Top: schematic of SPDC in a single AlGaAs disk nanoantenna which supports Mie resonances. Bottom: SEM image of the antenna (left) and the measured coincidences and the fitted Gaussian curve (right) [84]