In nanostructures, the dimensions of the material are on the order of the wavelength of light, which can enhance the nonlinear interactions. Materials such as plasmonic nanoparticles, photonic crystals, and nanowires are often used to exploit FWM. The confinement of light in these structures increases the local field intensity, thereby enhancing the nonlinear processes. This can lead to more efficient FWM, enabling the generation of new frequencies with lower input power.
