Modeling and linearly tunable multi-resonant hybrid metal–dielectric nanostructures to optimize nonlinear optical frequency conversions

With the establishment of optimal conditions for the fabrication of hybrid metal–dielectric nanostructures, the use of these configurations has led to the efficient generation of nonlinear optical phenomena. In this study, a hybrid metal–dielectric nanostructure composed of gold nanorods and a Y:HfO 2 dielectric layer has been designed to optimally generate nonlinear optical frequency conversions using the finite element numerical method. Calculating the linear spectral response of the nanostructure and tuning the number of gold nanorods has led to an appropriate multi-resonant response for optimal generation of second-order nonlinear optical conversions. Then, precise adjustment of the radiation and output frequencies at the resonant points of the nanostructure’s spectral response has led to a significant enhancement of the efficiency of sum- and difference-frequency generation phenomena. Investigating the variations in radiation frequencies shows that overlapping the output frequency of the nonlinear phenomenon with the resonant frequencies of the nanostructure’s spectral response can enhance and optimize the efficiency of second-order nonlinear optical conversions. The numerical results of this study can be applied to achieve coherent light sources across various spectral ranges for applications such as laser generation and tuning, as well as laser spectroscopy for material identification at subwavelength scales.