Absorption enhancement in visible range from Fano resonant silicon nanoparticle arrays embedded in single crystal Mg:Er:LiNbO3 synthesized by direct ion implantation

Abstract

Fano resonant Si nanoparticles (NPs) are synthesized in single-crystal Mg:Er:LiNbO3 using ion implantation and subsequent thermal annealing. The structural and optical properties of the Si NPs embedded in the crystal have been investigated. Spherical particles with radius of about 60 nm are observed by cross-sectional transmission electron microscope, while ion beam analysis are used to characterize the NPs formation process. The absorption of the Mg:Er:LiNbO3 crystals have been enhanced significantly due to the embedded Si NPs, which are induced by the Fano resonance effect in the visible light wavelength band. Periodic structures of spherical Si particles model is proposed and analyzed using the Mie theory to study the optical response features and local fields. As a result, numerical simulations demonstrate that periodicities of the array of Si NPs can yield narrow resonant peaks connected with multiple light scattering by the NPs and displaying a Fano-type resonant profile. The wavelengths of the absorption peak show clear red shift with increasing the radius of NPs and the peak intensity can be enhanced by decreasing the array period. This work opens an avenue to modulate the optical filed by embedding Fano resonant Si NPs for potential application in optical devices.