Graphene geometric diodes for terahertz rectennas (original) (raw)
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Terahertz antenna based on graphene
Journal of Applied Physics, 2010
We have investigated several configurations of antennas based on graphene. We show that patterned metallic dipole antennas or arrays of dipole antennas deposited on graphene highly benefit from the reversible high-resistivity-to-low-resistivity transition in graphene, tuned by a gate voltage. The radiation pattern and the efficiency of such antennas are changed via the gate voltage applied on graphene.
Antenna enhanced graphene THz emitter and detector
2015
Recent intense electrical and optical studies of graphene have pushed the material to the forefront of optoelectronic research. Of particular interest is the few terahertz (THz) frequency regime where efficient light sources and highly sensitive detectors are very challenging to make. Here we present THz sources and detectors made with graphene field effect transistors (GFETs) enhanced by a double-patch antenna and an on-chip silicon lens. We report the first experimental observation of 1-3 THz radiation from graphene, as well as four orders of magnitude performance improvements in a GFET thermoelectric detector operating at ~2 THz. The quantitative analysis of the emitting power and its unusual charge density dependence indicate significant non-thermal contribution from the GFET. The polarization resolved detection measurements with different illumination geometries allow for detailed and quantitative analysis of various factors that contribute to the overall detector performance. Our experimental results represent a significant advance towards practically useful graphene THz devices.
Evaluation of graphene-based terahertz photoconductive antennas
Scientia Iranica
Plasmonic mode propagation properties of a graphene strip placed on a substrate are studied in the THz range. Based on propagation properties (phase constant), a design guide for a dipole-like antenna made of graphene strips is presented. The input impedance and the radiation properties of such graphene-based antenna are investigated through full-wave numerical simulations. Full-wave simulations show that graphene antennas can provide higher input impedance, along with the tunability of the resonance frequency, which are two important design requirements in high performance terahertz photoconductive antenna sources and detectors.
Sub-wavelength Graphene Planar nanoantenna for THz Application
Materials Today: Proceedings, 2019
Owing to unique electronic and plasmonic properties at terahertz (THz) band, two-dimensional nano material graphene make it easy for the design of highly miniaturized ultra-wideband (UWB) reconfigurable THz antenna with simple nano structure at subwavelength scale. In this paper, a sub-wavelength miniaturized UWB reconfigurable graphene circular patch nanoantenna at THz band is reported. The simple structured graphene circular patch nanoantenna provides ultra-wideband of impedance bandwidth of 370%. The propagation of SPP waves in graphene THz antenna enables high miniaturization at THz band. At resonant frequency 0.75 THz, SPP wavelength λ SPP of the antenna is 10 times smaller than free space wavelength λ 0. Broad side radiation pattern with lower back lobe radiation is found at resonant frequency of the antenna. Moreover, frequency reconfiguration in the antenna is easily achievable by applying external voltage via Fermi energy of graphene. For a comparison propose, copper circular patch nanoantenna of the same dimension has been modelled in this work. Copper circular patch nanoantenna resonates at higher frequency 1.15 THz and provides a very narrow bandwidth. Compared to conventional copper metal antenna, graphene nanoantenna enables high miniaturization, UWB behavior, and easy reconfiguration. The proposed graphene nanoantenna can be promising for UWB THz applications.
Terahertz Detection and Imaging Using Graphene Ballistic Rectifiers
Nano Letters, 2017
A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a rectenna as a terahertz (THz) detector. A small-area (<1 μm 2) local gate is used to adjust the Fermi level in the device to optimize the output while minimizing the impact on the cutoff frequency. The device operates in both n-and p-type transport regimes and shows a peak extrinsic responsivity of 764 V/W and a corresponding noise equivalent power of 34 pW Hz −1/2 at room temperature with no indications of a cutoff frequency up to 0.45 THz. The device also demonstrates a linear response for more than 3 orders of magnitude of input power due to its zero threshold voltage, quadratic current−voltage characteristics and high saturation current. Finally, the device is used to take an image of an optically opaque object at 0.685 THz, demonstrating potential in both medical and security imaging applications.
The growing demand for sustainable energy generation has often pointed to solar energy as a very promising alternative. A new way to harvest solar energy is through solar rectennas. These systems are the integration of micro size antennas and nano diodes. In this way, electromagnetic energy can be captured and converted to the form of direct current. The challenges for the development of this technology are due to the submicron sizes since the theory that describes the operation of antennas moves away from classical electromagnetic behavior and incorporates quantum effects. At the same time, diodes operating in tens or hundreds of THz need specific properties. Within this context, this work presents an investigative study on solar rectennas for operation in THz range by using a bowtie antenna and a geometric diode, both based on graphene.
New THz opportunities based on graphene
2015
A number of THz signal-processing components are proposed. Firstly, a ballistic resonator is simulated for a graphene semiconductor structure. Graphene semiconductors have the advantage of exhibiting energy gaps depending on the width of the graphene sheet. Therefore loss free reflection of ballistic electrons as established by heterojunction epitaxy, can be realized by shaping the graphene widths. The design of corresponding THz oscillators is presented. Then quantum cascaded THz emitters are described. Finally, a number of basic components such as Schottky diodes on graphene transistors are discussed.
Graphene-based devices in terahertz science and technology
Journal of Physics D: Applied Physics, 2012
Graphene is a one-atom-thick planar sheet of a honeycomb carbon crystal. Its gapless and linear energy spectra of electrons and holes lead to nontrivial features such as giant carrier mobility as well as broadband flat optical response. In this paper recent advances in graphene-based devices in terahertz science and technology are reviewed. First, fundamental basis of the optoelectronic properties of graphene is introduced. Second, synthesis and crystallographic characterization of graphene material are described, particularly focused on the authors' original heteroepitaxial graphene-on-silicon technology. Third, nonequilibrium carrier relaxation and recombination dynamics in optically or electrically pumped graphene is described to introduce a possibility of negative dynamic conductivity in a wide terahertz range. Fourth, recent theoretical advances toward the creation of current-injection graphene terahertz lasers are described. Fifth, unique terahertz dynamics of the two-dimensional plasmons in graphene are described. Finally, the advantages of graphene devices for terahertz applications are summarized.
Graphene Based Terahertz Antenna Design for Modern Applications
International Journal of Innovative Research in Engineering and Management
In the Modern communication field, transmitting data through compact antennas like Microstrip patch antennas plays a major role. For Mobile radiolocation, satellite services, medical applications at Terahertz frequency range. Designing antennas for such applications at this frequency must have less weight and good characteristics. For this, graphene is the best suitable material for design due to its electrical, optical, and thermal conductivity properties. So, The Graphene-Based drilled substrate patch antenna 500 X 500 X 40 µm presents the simulation in the terahertz frequency. The prosed antenna structure is well suitable in the ISM (Industrial Scientific and Medical) band 1.36 THz-1.64THz 2.4 ~ 2.5 GHz. Its gives a high gain -20dB. Their Properties have been analyzed with CST for full-wave Simulations.