Photon-triplet emission in nonlinear resonant metasurface

Abstract

The photon-triplet emission from nonlinear dielectric metasurfaces supporting quasi-boundstates in the continuum (qBIC) is investigated. The approach utilizes the quantum-classical correspondence between third-order spontaneous parametric downconversion and its reverse classical process, three-wave sum-frequency generation (TSFG), to efficiently predict the photon-triplet generation (PTG) rate. Numerical simulations of non-collinear TSFG with degenerate input waves at qBIC wavelengths reveal a tunable emission profile with spatio-angular correlations. These results demonstrate the practicality of using quantum-classical correspondence to study PTG in arbitrary χ³ structures and also underscore the potential of resonant nonlinear metasurfaces as compact, free-space photon-triplet sources with quantum state control.