Sum-frequency generation
= Sum-frequency generation
{wiki=Sum-frequency_generation}
Sum-frequency generation (SFG) is a nonlinear optical process in which two photons with different frequencies interact within a nonlinear medium to produce a new photon with a frequency that is the sum of the two original frequencies. This process is based on the principle of nonlinear optics, where the polarization of a medium becomes dependent on the intensity of the electric field.