It is well known that reflection of a Gaussian light beam (TEM(00)) by a planar dielectric interface leads to four beam shifts when compared to the geometrical-optics prediction. These are the spatial Goos-Hanchen (GH) shift, the angular GH shift, the spatial Imbert-Fedorov (IF) shift, and the angular IF shift. We report here, theoretically and experimentally, that endowing the beam with orbital angular momentum leads to coupling of these four shifts; this is described by a 4 x 4 mixin

Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials. In such experiments, a laser pulse normally excites several nanostructures at once. However, spectroscopic information may also be acquired using pulses from an electron beam in a modern electron microscope, exploiting a phenomenon called cathodoluminescence. This approach offers several advantages. The multimode imaging capabilities of the electron microscope enable the correlation of optical properties (via cathodoluminescence) with surface morphology (secondary electron mode) at the nanometre scale. The broad energy range of the electrons can excite wide-bandgap materials, such as diamond- or gallium-nitride-based structures that are not easily excited by conventional optical means. But perhaps most intriguingly, the small beam can probe a single selected nanostructure. Here we apply an original time-resolved cathodoluminescence set-up to describe carrier dynamics within single gallium-arsenide-based pyramidal nanostructures with a time resolution of 10 picoseconds and a spatial resolution of 50 nanometres. The behaviour of such charge carriers could be useful for evaluating elementary components in quantum computers, optical quantum gates or single photon sources for quantum cryptography.

In general the experiments on the linear optical properties of a single-layer two-dimensional atomic crystal are interpreted by modeling it as a homogeneous slab with an effective thickness. Here I fit the most remarkable experiments in graphene optics by using the Fresnel coefficients, fixing both the surface susceptibility and the surface conductivity of graphene. It is shown that the Fresnel coefficients and the slab model are not equivalent. Experiments indicate that the Fresnel coefficients are able to simulate the overall experiments here analyzed, while the slab model fails to predict absorption and the phase of the reflected light

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