Showing 3 results for Terahertz
Reza Ghayoor, Alireza Keshavarz,
Volume 13, Issue 1 (1-2019)
Abstract
By developing the terahertz (THz) technology, in addition to generators and detectors of THz waves, the existence of some tools such as modulators and filters are needed. THz filters are important tools for various applications in the field of chemical and biological sensors. Linear and nonlinear optical properties of the graphene have attracted lots of attention. In fact graphene exhibits various nonlinear phenomena. Hence in this paper, by entering the graphene to the field of THz and using the graphene nonlinear properties with utilizing the transfer matrix method and transmission properties of a periodic structure containing graphene are investigated. A fairly straightforward computational method allows us to examine the effect of different structural parameters on the transmittance spectrum. Simulation results show that if the graphene nonlinear response in a periodic structure in the presence of a high-intensity THz field is considered, the proposed structure displays two bands of passes and stopping which can improve the design of the filters and controllers of THz waves.
Mohammad Amin Bani, Majid Nazeri, Ahmad Sajedi Bidgoli,
Volume 15, Issue 2 (7-2021)
Abstract
In this paper, the frequency response of a detector antenna is investigated when a layer of dielectric is placed on it. For this purpose, the surface wave theory has been used to explain the propagation of the current pulses in the antenna electrodes. Examinations are also performed of the propagation spectra of two types of terahertz antennas, bow-tie and dipole (with LT-GaAs substrates), on which the dielectrics of gallium arsenide and silica are located. These antennas are simulated through the CST software (FDTD method). The simulations show that the presence of a surrounding dielectric on the surface of an antenna affects the velocity of the current pulse propagation on the electrodes. It is also shown that the change in the thickness and position of the surrounding dielectric have a negative effect on quality of detector antenna by shift its spectral response to lower frequencies.
Zoha Ameri, Fazel Jahangiri,
Volume 16, Issue 2 (7-2022)
Abstract
Using terahertz waves for intra-body communications between nanomachines is associated with dissipation during propagation, of which scattering is one of the most important effects. In this paper, scattering path loss with two different assumptions of air-enclosed and tissue-enclosed in subcutaneous fat is calculated and compared. The results show that for TM polarization, air-enclosed assumption gives smaller and greater scattering loss for frequencies less and bigger than 0.26 THz. The greatest difference between air-enclosed and tissue-enclosed results is observed for TE polarization at the approximate frequency of 0.4 THz.
