Abstract
AbstractGaAs‐based semiconductors are highly attractive for diverse nonlinear photonic applications, owing to their non‐centrosymmetric crystal structure and huge nonlinear optical coefficients. Nanostructured semiconductors, for example, nanowires (NWs), offer rich possibilities to tailor nonlinear optical properties and further enhance photonic device performance. In this study, it is demonstrated highly efficient second‐harmonic generation in subwavelength wurtzite (WZ) GaAs NWs, reaching 2.5 × 10−5 W−1, which is about seven times higher than their zincblende counterpart. This enhancement is shown to be 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. The findings, therefore, provide an effective strategy for enhancing and manipulating the nonlinear optical response in subwavelength NWs by utilizing lattice engineering.
Highlights
The investigated GaAs NWs were grown by molecular beam epitaxy (MBE) on Si (111) or GaAs (111)B substrates
The SHG intensity was found to be significantly stronger in WZ NWs as compared with ZB NWs, reaching the value of 2.5 × 10−5 W−1
Www.afm-journal.de highest reported in the literature, including complex waveguide and nanoresonator structures, as well as hybrid plasmonic structures.[15,31,33,34]. Such enhancement was directly verified by correlative SHG intensity mapping and transmission electron microscopy (TEM) characterization performed on the same polymorphic NWs
Summary
The investigated GaAs NWs were grown by molecular beam epitaxy (MBE) on Si (111) or GaAs (111)B substrates. Pairs as determined by the weighted contribution of both dom ains.[13,14,16,19,46] The expected polar pattern is shown by the blue line in Figure 3c assuming that the two domains are present with the weight ratio of 0.53:0.47, as revealed by TEM Such polarimetric pattern is detected from our reference thick ZB NWs with d ≈ 400 nm (see Supporting Information). Even stronger deviations of the measured polar plots from the expected polarimetric pattern in bulk are observed in thin WZ NWs. The corresponding results are shown by the symbols in Figure 3e,f for the //- and ⊥-component, respectively. They show that this response can be efficiently controlled by changing the strength of the built-in electric field either optically or electrically
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