Nanostructure in holder
A close-up photo of the gold-coated nanostructure used in the experiments. It consists of a glass plate with a 1 cm x 1 cm area that has been etched with a shallow (40-nanometre deep) grating. Most of the glass plate is covered in a 30-nanometre thick layer of gold. The nanostructured area appears coloured because it diffracts light like the wings of a butterfly.