Anomalously strong second-harmonic generation in GaAs nanowires via crystal-structure engineeringGaAs-based semiconductors are highly attractive for diverse nonlinear photonic applications, owing to their non-centrosymmetric crystal structure and huge nonlinear optical coefficients. Nanostructured semiconductors, e.g., nanowires (NWs), offer rich possibilities to tailor nonlinear optical properties and further enhance photonic device performance. In this work, we demonstrate highly efficient second-harmonic generation in subwavelength wurtzite (WZ) GaAs NWs, reaching 2.5x10-5 W-1 that is about 7 times higher than that of their zincblende counterpart. We show that this enhancement is predominantly caused by an axial built-in electric field induced by spontaneous polarization in the WZ lattice, via electric field-induced second-order nonlinear susceptibility, and can be controlled optically and potentially electrically. Our findings, therefore, provide an effective strategy for enhancing and manipulating the nonlinear optical response in subwavelength NWs by utilizing lattice engineering.
The full article can be found here: https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.202104671