DescriptionMany fundamental phenomena in condensed matter have energies of the order of meV, and thus, they are suitable for THz probing. The wide range of mechanical and electronic phenomena includes lattice vibrations, intraband transitions and cyclotron resonances in semiconductors, the dynamics of complex fluids, electron spins, and strongly correlated electrons, specific rotations, vibrations or librations of molecules and molecular aggregates, etc. Unfortunately, accessing the THz spectrum has not always been easy. The emergence and commercialisation of THz time-domain spectrometers has revolutionised THz science and technology, and is transforming the landscape of condensed matter physics. To illustrate the power of THz time-domain spectroscopy for condensed matter physics, two systems will be discussed: a magnetized semiconductor and a dielectric-backed subwavelength slit array.
Due to the applied magnetic field, time-reversal symmetry is broken in the former system, which enables the existence of the three-dimensional analogue of graphene, the so-called Weyl points, and the corresponding photonic Fermi arcs. To characterize the Weyl points and the Fermi arcs, a magnetic field is applied parallel to the surface of an InSb slab that is maintained in a low-temperature environment of T=50 K. In addition, a grating is deposited on the InSb slab so as to compensate the in-plane momentum mismatch between the incident terahertz radiation and the Weyl points. The reflection spectra as a function of the applied magnetic field reveal the Weyl points and Fermi arcs.
Under TE-polarization illumination (i.e. incident E-field parallel to the slits), the latter subwavelength slit array system shows a dielectric-thickness-dependent high transmission peak known as extraordinary transmission. The study of the temporal dynamics of such system for different number of slits (i.e. truncation of the array) under different quasi-optical configurations reveals the role of the leaky-wave associated to the TE1 grounded-dielectric slab.
|Period||18 Sep 2020|
|Event title||V International Conference on Metamaterials and Nanophotonics|
|Degree of Recognition||International|
- Weyl point
- Extraordinary transmission
- time-domain spectroscopy
Project: Research Councils