Julien Perruisseau-Carrier

Reconfigurable terahertz plasmonic antenna concept using a graphene stack

The concept and analysis of a Terahertz (THz) frequency-reconfigurable antenna using graphene are presented. The antenna exploits dipole-like plasmonic resonances that can be frequency-tuned on large range via the electric field effect in a graphene stack. In addition to efficient dynamic control, the proposed approach allows high miniaturization and good direct matching with continuous wave THz sources. A qualitative model is used to explain the excellent impedance stability under reconfiguration. These initial results are very promising for future all-graphene THz transceivers and sensors. Keywords: Reconfigurable antenna, Graphene, Plasmons, Terahertz, frequency-tuning.

Design of tunable biperiodic graphene metasurfaces

Journal article Design of tunable biperiodic graphene metasurfaces Fallahi, Arya; Perruisseau-Carrier, Julien Published in: Physical Review B (ISSN: 1098-0121), vol. 86, num. 19 College Pk: Amer Physical Soc, 2012 Periodic structures with subwavelength features are instrumental in the versatile and effective control of electromagnetic waves from radio frequencies up to optics. In this paper, we theoretically evaluate the potential applications and performance of electromagnetic metasurfaces made of periodically patterned graphene. Several graphene metasurfaces are presented, thereby demonstrating that such ultrathin surfaces can be used to dynamically control the electromagnetic wave reflection, absorption, or polarization. Indeed, owing to the graphene properties, the structure performance in terms of resonance frequencies and bandwidths changes with the variation of electrostatic bias fields. To demonstrate the applicability of the concept at different frequency ranges, the examples provided range from microwave to infrared, corresponding to graphene features with length scales of a few millimeters down to about a micrometer, respectively. The results are obtained using a full-vector semianalytical numerical technique developed to accurately model the graphene-based multilayer periodic structures under study.

Analysis and design of terahertz antennas based on plasmonic resonant graphene sheets

Resonant graphene antennas used as true interfaces between terahertz (THz) space waves and a source/detector are presented. It is shown that in addition to the high miniaturization related to the plasmonic nature of the resonance, graphene-based THz antenna favorably compare with typical metal implementations in terms of return loss and radiation efficiency. Graphene antennas will contribute to the development of miniature, efficient, and potentially transparent all-graphene THz transceivers for emerging communication and sensing application.

Graphene-based plasmonic switches at near infrared frequencies

The concept, analysis, and design of series switches for graphene-strip plasmonic waveguides at near infrared frequencies are presented. Switching is achieved by using graphenes field effect to selectively enable or forbid propagation on a section of the graphene strip waveguide, thereby allowing good transmission or high isolation, respectively. The electromagnetic modeling of the proposed structure is performed using full-wave simulations and a transmission line model combined with a matrix-transfer approach, which takes into account the characteristics of the plasmons supported by the different graphene-strip waveguide sections of the device. The performance of the switch is evaluated versus different parameters of the structure, including surrounding dielectric media, electrostatic gating and waveguide dimensions.

Monolithic MEMS-Based Reflectarray Cell Digitally Reconfigurable Over a 360

In this letter, we present a reconfigurable reflectarray cell operating at 12 GHz and fabricated in a monolithic MEMS process. A 5-bit digital control allows reconfiguration of the reflection phase over the full 360deg range, while alleviating the impact of MEMS and bias voltage tolerances on the device performances. The designed reflectarray cell exhibits low frequency phase error (large bandwidth) and excellent measured reflection loss (-0.3 dB) with regard to state-of-the-art. Close agreement between measurements and full-wave simulations is observed.

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This paper proposes the concept, analysis and design of a sinusoidally modulated graphene leaky-wave antenna with beam scanning capabilities at a fixed frequency. The antenna operates at terahertz frequencies and is composed of a graphene sheet transferred onto a back-metallized substrate and a set of polysilicon DC gating pads located beneath it. In order to create a leaky-mode, the graphene surface reactance is sinusoidally modulated via graphenes field effect by applying adequate DC bias voltages to the different gating pads. The pointing angle and leakage rate can be dynamically controlled by adjusting the applied voltages, providing versatile beamscanning capabilities. The proposed concept and achieved performance, computed using realistic material parameters, are extremely promising for beamscanning at THz frequencies, and could pave the way to graphene-based reconfigurable transceivers and sensors.

Phase Range

The use of graphene for fixed-beam reflectarray antennas at Terahertz (THz) is proposed. Graphenes unique electronic band structure leads to a complex surface conductivity at THz frequencies, which allows the propagation of very slow plasmonic modes. This leads to a drastic reduction of the electrical size of the array unit cell and thereby good array performance. The proposed reflectarray has been designed at 1.3 THz and comprises more than 25000 elements of size about λ0/16. The array reflective unit cell is analyzed using a full vectorial approach, taking into account the variation of the angle of incidence and assuming local periodicity. Good performance is obtained in terms of bandwidth, cross-polar, and grating lobes suppression, proving the feasibility of graphene-based reflectarrays and other similar spatially fed structures at Terahertz frequencies. This result is also a first important step toward reconfigurable THz reflectarrays using graphene electric field effect.

Sinusoidally Modulated Graphene Leaky-Wave Antenna for Electronic Beamscanning at THz

A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-beam reflectarrays, or similarly to implement the so-called generalized law of reflection. The change in the complex conductivity of graphene when biased by an electric field allows controlling the phase of the reflected field at each element of the array. Additionally, the slow wave propagation supported by graphene drastically reduces the dimensions of the cell, which allows smaller inter-element spacing hence better array performance. An elementary cell is optimized and its scattering parameters computed, demonstrating a dynamic phase range of 300° and good loss figure for realistic chemical potential variations. Finally, a circuit model is proposed and shown to very accurately predict the element response.

Reflectarray Antenna at Terahertz Using Graphene

An approach for transmitting multiple signals using a single switched parasitic antenna (SPA) has been recently reported. The idea there is to map the signals to be transmitted onto a set of basis functions that serve as “virtual antennas” in the beamspace (i.e., wavevector) domain. In this paper, we generalize the derivation of the antenna pattern basis functions regarding a three-element SPA of arbitrary radiating elements, within a symmetric array topology, for multiplexing signals in the wavevector domain (using different beampatterns) rather than in the hardware antenna domain with multiple feeding ports. A fully operational antenna system example is modeled, optimized regarding its return loss and the power imbalance between the basis functions, and finally realized. The measurements of the SPA show good agreement with the simulated target values, revealing an accurate design approach to be adopted as a fast SPA prototyping methodology. The SPA has been successfully employed for multiplexing two binary phase-shift-keying (BPSK) datastreams over-the-air, thus paving the way for practically compact and highly efficient MIMO transceiver designs.

Tunable graphene reflective cells for THz reflectarrays and generalized law of reflection

The experimental characterization of the surface impedance of monolayer graphene at micro and millimeter wave frequencies is addressed. Monolayer graphene is transferred on a substrate stack, which is placed in the cross-section of a rectangular waveguide. In the fundamental mode, this setup is equivalent to a TE-polarized plane wave impinging under oblique incidence on an infinite graphene sheet, and similarly, the surface impedance of the graphene is a simple lumped element in a transmission-line model, that exactly represents the electromagnetic problem under study. Using this model, we propose a technique based on transmission matrices to accurately extract the surface impedance. The method is able to relax the influence of the substrates tolerances by taking advantage of the graphene infinitesimally small electrical thickness. It can also account for any gap between the sample and the test waveguide, thereby allowing to disregard graphene-metal contact resistance issues. The approach has been success...