Enhanced generation of angle correlated photon-pairs in nonlinear metasurfaces
Andrea Mazzanti, Matthew Parry, Alexander N. Poddubny, Giuseppe Della Valle, Dragomir N. Neshev, Andrey A. Sukhorukov
Abstract
Abstract We reveal that strongly enhanced generation of photon pairs with narrow frequency spectra and sharp angular correlations can be realised through spontaneous parametric down-conversion in metasurfaces. This is facilitated by creating meta-gratings through nano-structuring of nonlinear films of sub-wavelength thickness to support the extended bound state in the continuum resonances, associated with ultra-high Q -factors, at the biphoton wavelengths across a wide range of emission angles. Such spectral features of photons can be beneficial for various applications, including quantum imaging. Our modelling demonstrates a pronounced enhancement, compared to unpatterned films, of the total photon-pair generation rate normalized to the pump power reaching 1.75 kHz mW −1 , which is robust with respect to the angular bandwidth of the pump, supporting the feasibility of future experimental realisations.