A nonlinear converter may comprise: alternating layers of a dielectric material and a metal material; a first refractive index of the nonlinear converter for a first wavelength (i.e., input wavelength or pump wavelength) between 207 nm and 237 nm, the first refractive index being less than 0.5, the first refractive index corresponding to metal fill ratio; and a second refractive index of the nonlinear converter for a second wavelength (i.e., output wavelength or SHG wavelength), the second wavelength being approximately double the first wavelength, the second refractive index corresponding to the metal fill ratio.