Demonstration of spectral and spatial interferometry at THz frequencies.

A laboratory prototype spectral-spatial interferometer has been constructed to demonstrate the feasibility of the double-Fourier technique at far infrared (FIR) wavelengths (0.15-1 THz). It is planned to use this demonstrator to investigate and validate important design features and data-processing methods for future astronomical FIR interferometer instruments.

Controlling the optical near field of nanoantennas with spatial phase-shaped beams.

We report on a novel approach, based on sub-wavelength spatial phase variations at the focus of high-order beams, to reconfigure the optical near field distribution near plasmonic nanostructures. We first show how the introduction of phase jumps in the incident field driving a gap nanoantenna strongly affects its near field response. Beyond, we demonstrate the feasibility of exploiting this approach to selectively switch on and off hot-spots sites within a complex antenna architecture.

Characterization of optical beams with spiral phase interferometry.

In this paper we study both theoretically and experimentally a method to characterize the amplitude and phase of a paraxial optical beam. The method is based on the spiral phase interferometry technique, recently proposed. We theoretically analyze how to adapt the original proposal to deal with the special characteristics of finite optical beams.