0000000000089876
AUTHOR
Rafal Kotynski
Asymmetric transmission of terahertz radiation through a double grating.
We report on experimental evidence of unidirectional transmission of terahertz waves through a pair of metallic gratings with different periods. The gratings are optimized for a broadband transmission in one direction, accompanied with a high extinction rate in the opposite direction. In contrast to previous studies, we show that the zero-order nonreciprocity cannot be achieved. Nonetheless, we confirm that the structure can be used successfully as an asymmetric filter.
Some considerations on the transmissivity of trirefringent metamaterials
Nonlocal effects in metal–dielectric (MD) periodic nanostructures may typically be observed when the plasmonic particles and gaps are on the scale of a few tens of nanometers, enabling under certain conditions (succinctly for epsilon near zero) a collimated beam to split into three refracted signals. We developed a method for precisely evaluating the categorized transmissivity in an air/trirefringent metamaterial interface, which uses a fast one-dimensional Fourier transform and finite element solvers of Maxwell’s equations. In periodic arrays of MD nanofilms, it is proved a tunable transmissivity switch of the multirefracted beams under varying angle of incidence and wavelength, while keep…
Asymmetric transmission of transverse magnetic or radially polarized THZ waves through sub-wavelength gratings
We have developed a metallic double circular grating with sub-wavelength slits which blocks radially polarized light incident from one of its sides and acts as a focusing diffractive element in the other direction. The proposed grating has been optimized for the sub-THz frequency range. Unidirectional transmission through the grating has been demonstrated experimentally at 0.1 THz. We have also developed a planar metallic double grating with sub-wavelength slits which blocks light with a transverse magnetic polarization incident from one of the grating sides and transmits radiation incident from the opposite direction into the +1 and −1 diffraction orders. These gratings which could be used…
Broadband asymmetric transmission of THz radiation through double metallic gratings
We analyse numerically and experimentally the asymmetric transmission through sub-wavelength double metallic gratings. The possibility of achieving a broadband unidirectional transmission of THz waves through the grating is confirmed. The proposed gratings allow for efficient one-way transmission in the wavelength range from 2.5 to 3.5 mm.