11 documents found, page 1 of 2
Replacing the Gallium Oxide Shell with Conductive Ag: Toward a Printable and Re...
Hajalilou, Abdollah; Parvini, Elahe; Morgado, Tiago A.; Lopes, Pedro Alhais; Jorge, M. Estrela Melo; Freitas, Marta; Tavakoli, MahmoudLiquid metal (LM)-based composites hold promise for soft electronics due to their high conductivity and fluidic nature. However, the presence of α-Ga2O3 and GaOOH layers around LM droplets impairs conductivity and performance. We tackle this issue by replacing the oxide layer with conductive silver (Ag) using an ultrasonic-assisted galvanic replacement reaction. The Ag-coated nanoparticles form aggregated, poro...
Non-Hermitian linear electro-optic effect in three-dimensional materials
Morgado, Tiago A.; Rappoport, Tatiana Gabriela; Tsirkin, Stepan S.; Lannebère, Sylvain; Souza, Ivo; Silveirinha, Mário G.Here, we present an in-depth theoretical analysis of the linear electro-optic effect in low-symmetry three-dimensional (3D) conductive materials with large Berry curvature dipoles. Our study identifies two distinct kinetic contributions to the linear electro-optic effect: a gyrotropic Hermitian (conservative) piece and a non-Hermitian term that can originate optical gain. We concentrate on the study of 3D mater...
Engineering Transistorlike Optical Gain in Two-Dimensional Materials with Berry...
Rappoport, Tatiana G; Morgado, Tiago A.; Lannebère, Sylvain; Silveirinha, Mário G.Transistors are key elements of electronic circuits as they enable, for example, the isolation or amplification of voltage signals. While conventional transistors are point-type (lumped-element) devices, it may be interesting to realize a distributed transistor-type optical response in a bulk material. Here, we show that low-symmetry two-dimensional metallic systems may be the ideal solution to implement such a...
Experimental verification of magnetic near-field channeling using a helical-sha...
Morgado, Tiago A.; João, Guilherme; Pereira, Ricardo A. M.; Fernandes, David E.; Lannebère, SylvainThis article was published in Applied Physics Letters; We experimentally verify that a magnetic uniaxial wire medium lens consisting of a racemic array of helical-shaped metallic wires may enable channeling the normal component of the magnetic field of near-field sources with resolution well below the diffraction limit over a broad bandwidth. It is experimentally demonstrated that the helical-shaped wire medium...
Single-interface Casimir torque
Morgado, Tiago A.; Silveirinha, Mário G.Adifferent type of Casimir-type interaction is theoretically predicted: a single-interface torque at a junction of an anisotropic material and a vacuum or another material system. The torque acts to reorient the polarizable microscopic units of the involved materials near the interface, and thus to change the internal structure of the materials. The single-interface torque depends on the zero-point energy of th...
Super-collimation of the radiation by a point source in a uniaxial wire medium
Morgado, Tiago A.; Silveirinha, Mário G.We investigate the radiation properties of a short horizontal dipole embedded in a uniaxial wire medium. It is shown that the uniaxial wire medium enables a super-collimation of the dipole radiation such that the radiation pattern has a singularity and the radiated fields are non-diffractive in the broadside direction. We derive a closed analytical formula for the power radiated by the dipole in the wire medium...
Analytical solution for the stopping power of the Cherenkov radiation in a unia...
Morgado, Tiago A.; Fernandes, David E.; Silveirinha, MárioThis article was published in Photonics 2015, 2(2), 702-718; We derive closed analytical formulae for the power emitted by moving charged particles in a uniaxial wire medium by means of an eigenfunction expansion. Our analytical expressions demonstrate that in the absence of material dispersion the stopping power of the uniaxial wire medium is proportional to the charges velocity, and that there is no velocity ...
Spatially confined UHF RFID detection with a metamaterial grid
Morgado, Tiago A.; Alves, Jorge M.; Marcos, João S.; Maslovski, Stanislav I.; Costa, Jorge R.; Fernandes, Carlos A.; Silveirinha, Mário G.The confinement of the detection region is one of the most challenging issues in Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) systems. Here, we propose a new paradigm to confine the interrogation zone of standard UHF RFID systems. Our approach relies on the use of an all-planar metamaterial wire grid to block the radiation field (i.e., the far-field) of the reader antenna, and thereby obtain...
Uniaxial indefinite material formed by helical-shaped wires
Morgado, Tiago A.; Maslovski, Stanislav I.; Silveirinha, Mário G.We demonstrate that a racemic array of helical-shaped metallic wires may be regarded as a local uniaxial epsilon-negative (ENG) material even when the metal conductivity is very large (e.g. in the microwave regime) and, as a result, enables strong negative refraction over a wide frequency range. Based on the negative refraction effect, we demonstrate partial focusing of p-polarized electromagnetic radiation usi...
Generalized additional boundary conditions for wire media
Maslovski, Stanislav I.; Morgado, Tiago A.; Silveirinha, Mário G.; Kaipa, Chandra S. R.; Yakovlev, Alexander B.We generalize additional boundary conditions (ABCs) for wire media by including arbitrary wire junctions with impedance loading. Special attention is given to the conditions at the interface of two uniaxial wire media with metallic patches at the junction. The derived ABCs are validated against full-wave numerical simulations.