Local investigation of the optical properties of subwavelength rectangular holes with a focused beam of electrons.

The optical properties of rectangular subwavelength holes in a gold film are investigated using the light generated when a focused beam of electrons impinges on the sample close to the hole. Using this technique, multi-spectral maps of the holes are obtained with a resolution beyond the optical diffraction limit. The results show the influence of hole shape on the spectrum of locally scattered light. Rectangular holes of varying shape and size are investigated, and the spatial distribution of the polarization of the observed light is measured. The influence of neighbouring holes is investigated by measuring small clusters of holes.