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The broadband complex conductivities of transparent conducting oxides (TCO), namely, aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO) and tin-doped indium oxide (ITO), were investigated by using THz-TDS from 0.5 to 18 THz. The complex conductivities were accurately calculated using a thin film extraction algorithm and analyzed in terms of the Drude conductivity model. We find that a...
Ultrafast electron field emission from gold resonant antennas induced by strong terahertz (THz) transient is investigated using two THz pulse experiments. It is shown that UV emission from nitrogen plasma generated by liberated electrons is a good indication of the local electric field at the antenna tip. Using this method resonant properties of antennas fabricated on high resistivity silicon are...
In this work, a new design aimed to perform as a half-wavelength plate in the terahertz regime is presented. The fabricated samples exhibit a phase difference of 180° at 0.73 THz between the two principal polarisations that matches with the modelling results. The experimentally determined transmittances of the two polarisations were around 61 %, which is below theoretical predictions of reaching more...
We report the first observation of THz-field-induced electromigration in sub-wavelength metallic gap structures after exposure to intense single-cycle, sub-picosecond electric field transients of amplitude up to 400 kV/cm.
We present a design of periodically arranged microslits in a gold film for nonlinear terahertz phonon spectroscopy. Global optimization of array parameters gives a field enhancement of more than 50, due to plasmonic coupling between individual slits.
We experimentally show that metallic dipole antennas emit ultraviolet radiation when illuminated with ultrashort high-power terahertz pulses due to ultrafast electron field emission from the metal and consecutive ionization and excitation of atmospheric gas molecules.
Using a THz camera and THz bandpass filters, we measure the frequency-resolved beam profile emitted from a two-color air plasma. We observe a frequency-independent emission angle from the plasma.
Using a metamaterial composite, we demonstrate a bandpass filter that has only a single transmission mode from 0 to >25 THz. This usable bandwidth matches, or exceeds, that of currently used THz sources.
We experimentally demonstrate photoluminescence from nanostructured ultrathin gold films subjected to strong single-cycle terahertz transients with peak electric field over 300 kV/cm. We show that UV-Vis-NIR light is being generated and the efficiency of the process is strongly enhanced at the percolation threshold.
In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission...
We proposed a simple scheme to make a continuous metallic film on a semi-infinite substrate optically transparent, thus obtaining a completely transparent electrode in a desired frequency range. By placing a sub-wavelength composite layer consisting of dielectric and metallic stripes on top of the metallic one, we found that the back-scattering from the metallic film can be almost perfectly canceled...
We perform ultrabroadband THz spectroscopy of the dielectric function of arsenic trisulfide (As2S3). We observe the transition from universal scaling of the absorption at low frequencies to medium- and short-range-order at higher frequencies.
The concept of metamaterials (MTMs) is acknowledged for providing new horizons for controlling electromagnetic radiations thus their use in frequency ranges otherwise difficult to manage (e.g. THz radiation) broadens our possibility to better understand our world as well as opens the path for new applications. THz radiation can be employed for various purposes, among them the study of vibrations in...
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