Second-harmonic generation in amorphous silicon-based materials

Abstract

This work explores the electric field-induced second-harmonic (EFISH) effect in amorphous silicon-based materials, such as SiNx, SiOx, and silicon nanocrystals embedded in a silicon oxide matrix. Since EFISH allows the induction of a sizable voltage-controllable second-order nonlinearity (χ(2)) by applying a DC field in any dielectrics with a sufficient large third-order nonlinearity (χ(3)), it offers an effective method to turn the used material in a second-order nonlinear platform even so it does exhibit a centrosymmetric or amorphous structure prohibiting a conventional χ(2). In detail, the presented experimental results show that specific χ(2) tensor components can be selectively accessed by adjusting the direction of the applied DC field. Furthermore, a potential enhancement of EFISH through quantum confinement effect and periodic photonic nanostructures is investigated. In this way, a high degree of functionality of the EFISH effect in photonic structures is demonstrated.