Reshaping gold micro and nano structures with polarization dependent photothermal annealing

We report a novel polarization dependent photothermal annealing technique for fine-tuning the shape of metallic micro- and nano-structures with flood exposure of nanosecond laser pulses after they are fabricated. This is realized by utilizing the local field enhancement due to collective electron oscillation on metallic nanostructures driven by electromagnetic waves. We have demonstrated that pre-patterned Au squares can be annealed into Au nanospheres; circular disks into elliptical disks; and rectangular Au microwires into Au nanowires with different aspect ratios.