Strong enhancement of second-harmonic generation in all-dielectric resonant waveguide grating

The authors demonstrate that a dielectric resonant waveguide grating can enhance optical second-harmonic generation by a factor of 550 compared to a similar flat surface. Their structure, which consists of purely dielectric and thereby transparent materials, has a low index silicon dioxide grating covered by a high index titanium dioxide layer and it is optimized for the fundamental wavelength of 1064 nm. Polarization dependence of the second-harmonic response suggests that the enhancement arises from the favorable interaction of the resonant waveguide mode and its strong local field with the inherent surface nonlinearity of the dielectric materials.Peer reviewe