  We report a direct observation on the unique laterally emitted surface second
harmonic generation (SHG) in a single ZnTe nanowire. The highly directional
surface SHG signal that polarizes along the direction vertical to the nanowire
growth axis, is significantly larger than the bulk SHG contribution, indicating
a high efficiency of surface SHG. Two strong SHG peaks are observed on both
sides of the nanowire surfaces in the far-field scanning images, which is
further supported by FDTD simulations, demonstrating that the unique laterally
emitted signal is ascribed to surface SHG in the ZnTe nanowire. The surface SHG
in a single ZnTe nanowire with unique lateral emission and high conversion
efficiency shows great potential applications in short-wavelength nanolasers,
nonlinear microscopy and polarization dependent photonic integrating.
