Here the engineering of anisotropic plasmonic metasurfaces in the form of nanostripes or nanostripe dimers is demonstrated by a novel self-organization technique. Subwavelength quasi-1D glass templates are fabricated over large (cm2) area by ion beam induced wrinkling, enabling the maskless confinement of out-of-plane tilted gold nanostripe arrays supporting localized plasmon resonances easily tunable from the Visible to the Near-Infrared spectrum. A multi-step variant of the method allows to achieve plasmon hybridization in Au-silica-Au nanostrip dimer arrays with excitation of plasmonic electric dipole and magnetic dipole mode featuring strong subradiant near-field enhancement. The selforganized method enables to tune the hybridized plasmonic mode in the Visible and Near-Infrared spectrum opening the possibility to exploit these templates in highly sensitive biosensing and/or nonlinear optical spectroscopies.
Near-field imaging techniques at terahertz (THz) frequencies are severely restricted by diffraction. To date, different detection schemes have been developed, based either on sub-wavelength metallic apertures or on sharp metallic tips. However high-resolution THz imaging, so far, has been relying predominantly on detection techniques that require either an ultrafast laser or a cryogenically-cooled THz detector, at the expenses of a lack of sensitivity when high resolution levels are needed. Here, we demonstrate two novel near-field THz imaging techniques able to combine strongly sub-wavelength spatial resolution with highly sensitive amplitude and phase detection capability. The first technique exploits an interferometric optical setup based on a THz quantum cascade laser (QCL) and on a near-field probe nanodetector, operating at room temperature. By performing phase-sensitive imaging of THz intensity patterns we demonstrate the potential of our novel architecture for coherent imaging with sub-wavelength spatial resolution improved up to 17 μm. The second technique is a detector-less s-SNOM system, exploiting a THz QCL as source and detector simultaneously. This approach enables amplitude- and phase-sensitive imaging by self-mixing interferometry with spatial resolution of 60-70 nm.