Linear and nonlinear optical properties of gold nanoparticles with broken symmetry

We describe our research involving arrays of gold nanoparticles fabricated with electron beam lithography. Small defects in the particles introduced during the fabrication process result in broken design symmetry. The broken symmetry renders the arrays chiral, and signatures of chirality can be observed in both the linear and nonlinear optical responses through precise polarization measurements. The defects enhance the local electric field, enabling more efficient nonlinear optical generation and therefore making nonlinear optical measurements more sensitive to their presence. We also discuss future objectives for clarifying the microscopic processes underlying the optical responses in gold nanoparticle arrays.