Recently, metasurfaces have broken new ground in high-field attosecond science. We demonstrate the ability to control recolliding electrons and holes using a plasmonic metasurface, which results in the emis-sion of high harmonics with controlled polarization and phase. Our metasurface enhances circularly polar-ized harmonics by approximately 43 times compared to unpatterned surfaces.

A bull’s-eye plasmonic antenna is exploited to enhance terahertz (THz) field detection by boosting the efficiency of nonlinear interaction in electro-optic sampling (EOS). Device performance is optimized numerically by targeting perfect spatiotemporal overlap between a near-infrared gating pulse and a locally enhanced THz field in a long nonlinear interaction length. The metallic bull’s-eye antenna is fabricated on a gallium phosphide crystal with a maskless laser direct writing technique. We experimentally demonstrate broadband EOS detection with 2.5 times higher sensitivity.

We introduce a terahertz plasmonic signal processor, realized by inducing a phase transition in a two-wire waveguide Bragg grating. This phase transition leads to a transmission peak within the forbidden band.

A terahertz (THz) vortex beam is generated through a spiral phase plate fabricated via two-photon polymerization lithography (TPL). TPL is a three-dimensional (3D) printing technique that exhibits high resolution and low surface roughness enabling the fabrication of high-frequency THz devices. The SPP is characterized via a scanless THz time-domain imaging (TDI) technique that allows to obtain a coherent hyperspectral analysis of the generated vortex beam. Numerical simulations are also conducted for comparison with experiments, revealing a good agreement.

In this experimental work, we take profit of the non-hermitian nature of photonic systems to engineer topological interface states in a synthetic dimension. To achieve this, we use the frequency eigenmodes of a modulated optical fiber loop, acting as a ring cavity, to encode extended versions of the Su-Schrieffer-Heeger Hamiltonian including complex long-range couplings. By driving the system with a laser at a well-defined frequency, we demonstrate the onset of localized interfaces through the interplay of drive and dissipation.