In this work, amplitude modulator of terahertz radiation was fabricated and experimentally studied. The sample consists of two plastic substrates, internally coated with multilayer graphene, the cavity between the plates was filled with ion gel. The fabricated sample was studied by terahertz time-domain spectroscopy method. In the experiment, waveforms of terahertz pulse transmitted through the sample at different applied DC voltage were obtained. It was shown that with increasing DC voltage, the amplitude of the transmitted terahertz radiation decreases. The results may be used to design attenuators and modulators for terahertz communication.
Dynamical manipulation of electromagnetic radiation in arbitrary manner is achievable through metasurface utilization. Significant issue for practical applications of metasurfaces is in solving inverse problem, i.e. prediction of metasurface pattern dimensions in accordance to the desired electromagnetic response. In this work, we propose the approach based on equivalent circuit model enabling to connect resonant features of metasurface with its geometry dimensional parameters.
In this work, we propose and theoretically investigate the first dynamically tunable metasurface based on new twodimensional (2D) material - multi-layer graphene (MLG). As a basis for metasurface development, the results of experimental studies in THz frequency band of 80-layered graphene on dielectric substrate under external optical pumping were used. The metasurface consist of the Polymethylpentene (TPX) substrate and cross-shaped MLG pattern. In addition, the structure of the metasurface is very simple and can be fabricated by chemical vapor deposition and laser engraving. Proposed non-metallic metasurface is high-potential candidate for designing an active THz devises.
In this work, we study infrared optical pump-induced changes in terahertz conductivity of multi-layer graphene on a silicon substrate using terahertz time-domain spectroscopy. Results indicate that the conductivity and optical parameters of investigated material strongly depend on a pumping intensity and the presence of FeCl3 molecules intercalation. The findings are helpful for determining the most optically tunable material towards designing of optically controllable terahertz devices based on new two-dimensional material beyond graphene monolayer.
Recent decades metamaterials in terahertz frequencies become very popular in the scientific society. Metamaterials is an arrangement of artificial structural elements (unit cell) that gives properties which cannot be found in nature. The effective properties of metamaterials depend on their design. This fact provides a big variety in applications of metamaterials as filters, absorbers, polarizers, etc.
In this work we have studied the influence of the chiral metasurface resonator conductivity on polarizing properties of the metasurface. The unit cell of the metasurface consists of metallic gammadion crosses on both sides of the dielectric substrate. The petals of the upper resonators were partly made of different metals. Each combination of metals in design of the resonator leads to a difference in transmission of the metasurface. Due to chirality, transmission coefficients for left- and right-handed polarized waves are different. This phenomenon causes changes in the polarization ellipse of transmitted wave. The metasurface was numerically simulated using CST Microwave Studio by finite-elements method in frequency domain. The virtual experiment shows a difference in ellipticity and azimuth polarization rotation angle spectra of resonators with different conductivity. These results provide usage of materials with changeable conductivity, for example, graphene, in development of tunable polarization converter.
The investigated metasurface might be used in terahertz polarimetry of cancer, teeth and skin deceases. These measurements can be performed by terahertz time-domain spectroscopy.
The polarizing properties of chiral metasurface made of planar array of gammadion crosses placed on silicone
substrate were investigated in the frequency range of 0.1-0.3 THz. The ability of polatization properties control
of metasurface working as elliptic polarizer by gammadion petal width changing was shown.
We propose a high-Q optically tunable terahertz (THz) filter consisting of subwavelength multilayer graphene/ dielectric/metal asymmetric square split-ring resonators (SRR) within a unit cell. The obtained simulation results demonstrate that Fano resonance can be efficiently modulated under IR-radiation of different intensity value. The modulation depth of Fano resonance can achieve about 60% under the maximum considered pumping intensity (corresponding to 0.4 eV of Fermi energy) with the Q-factor of about 135. The proposed metasurface provides narrow filtering of incident light as well as sensing applications.
This paper presents an investigation of terajets formation by dielectric periodic structure at terahertz frequencies in effective medium regime (photonic metamaterial). The dispersions of effective permittivity for three periodic structures formed by different types of plastics (ABS, PLA, Crystal) were analytically obtained for both regimes. Numerical simulation of this structure was performed by using COMSOL Multiphysics. The terajet formation was numerically shown.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.