Figure : Scaling of the measured intensity as a function of pump fluence for SHG, THG, and mPL processes for various (RNH 3 ) 2 (MA) n-1 Pb n I 3n+1 2D-RP perovskite samples. Straight lines are guides to the eye for quadratic (blue) and cubic (magenta) scaling. All measurements were performed with ω = 0.99 eV except for the PEA n = 2, TPMA n = 2, and TPMA n = 3 SHG measurements which were performed with ω = 1.05 eV. For SHG and THG, the monochromator was set to the second and third harmonics of the fundamental frequency, respectively, while for mPL the monochromator was set to the maximum of the mPL spectrum (see Figure for spectra).