Furthermore, our assignments of SHG, THG, and mPL are confirmed by measuring each feature's output intensity scaling as a function of excitation laser fluence. The data presented in Figure demonstrate the expected quadratic (Equation ) and cubic (Equation ) output intensity scaling for SHG and THG, respectively. Slight saturation is present at the highest fluences. The mPL feature has cubic or higher scaling which indicates that the photoluminescence is excited by a three or more photon process.