Highly Sensitive Detection of the Lattice Distortion in Single Bent ZnO Nanowires by Second-Harmonic Generation Microscopy

We demonstrate a highly sensitive detection of the lattice distortion in single bent ZnO nanowires (NWs) by second-harmonic generation (SHG) microscopy. As the curvature of the single bent ZnO NW increases to 21 mm(-1) (<4% bending distortion), it shows a significant decrease (similar to 70%) in the SHG intensity ratio between perpendicular and parallel excitation polarization with respect to c-axis of ZnO NWs. A high detection sensitivity of 10(-3) nm on the bending distortion is obtained in our experiment. Importantly, the extraordinary nonaxisymmetrical SHG polarimetric patterns are also observed, indicating the twisting distortion around c-axis of ZnO NWs. Thus, SHG microscopy provides a sensitive all-optical and noninvasive method for in situ detecting the lattice distortion under various circumstances.