Nanocrystalline resonant silicon nanoparticle for highly efficient second harmonic generation

Silicon is a centrosymmetric material, and the studies of nonlinear optical properties of silicon nanoparticles are primarily targeting the third-harmonic generation effects. Here we demonstrate that resonantly excited nanocrystalline silicon nanoparticles fabricated by an optimized laser printing technique exhibit strong second-harmonic generation (SHG) effects. We attribute an unexpectedly high yield of the nonlinear conversion to a nanocrystalline structure of nanoparticles supporting the Mie resonances. Our finding may open novel prospects for a design of nonlinear subwavelength light sources with exceptional functionalities fully integrated in Si-based nanoscale photonic circuits.