Linear and second-order nonlinear optical properties of arrays of noncentrosymmetric gold nanoparticles

The optical properties of nanoscopic arrays of metal particles are dominated by plasmon resonances and electromagnetic interaction between the particles. We use electron-beam lithography to prepare arrays of noncentrosymmetric gold particles and study their linear and second-order nonlinear optical properties. By varying the orientation of the particles in a fixed lattice, we observe shifts in the polarized linear extinction spectra. The second-harmonic generation efficiencies of the two types of samples differ by up to 60%. The results show that the properties of the samples are sensitive to the smallest details of their structure.