Fig. 6: Spontaneous parametric down converison (SPDC).
From: AlGaN/AlN heterostructures: an emerging platform for integrated photonics
An optimized heterostructure of AlxGa1−xN for entangled photon pair generation at 1550 nm. a Second-order nonlinear susceptibility tensor element χ33, b vertical component of the electric field of the higher order TM mode at 775 nm, c the fundamental TM mode at 1550 nm, and d effective index difference between these two modes as a function of pump laser wavelength.
