Plasmonic response of a nanorod in the vicinity of a metallic surface: local approach with analytical solution

In this paper we present an analytical solution for the eigenmodes and corresponding electric fields of a composite system made of a nanorod in the vicinity of a plasmonic semi-infinite metallic system. To be specific, we choose Silver as the material for both the nanorod and the semi-infinite metal. The system is composed of two sub-systems with different symmetries: the rod has polar symmetry, while the interface has a rectangular one. Using a boundary integral method, proposed by Eyges, we are able to compute analytically the integrals that sew together the two systems. In the end, the problem is reduced to a one of linear algebra, where all the terms in the system are known analytically. For large distances between the rod and the planar surface, only a few of those integrals are needed and a full analytical solution can be obtained. Our results are important to benchmark other numerical approaches and represent a starting point in the discussion of systems composed of nanorods and two-dimensional materials.N M R P thanks Andre Gonvalves and Bruno Amorim for many discussions on the topic of plasmonics. N M R P acknowledges support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020, support from the European Commission through the project 'Graphene-Driven Revolutions in ICT and Beyond' (Reference No. 881603, CORE 3), COMPETE 2020, PORTUGAL 2020, FEDER and the FCT through projects POCI-01-0145-FEDER-028114

Enhanced Optical Dichroism of Graphene Nanoribbons

The optical conductivity of graphene nanoribbons is analytical and exactly derived. It is shown that the absence of translation invariance along the transverse direction allows considerable intra-band absorption in a narrow frequency window that varies with the ribbon width, and lies in the THz range domain for ribbons 10-100nm wide. In this spectral region the absorption anisotropy can be as high as two orders of magnitude, which renders the medium strongly dichroic, and allows for a very high degree of polarization (up to ~85) with just a single layer of graphene. The effect is resilient to level broadening of the ribbon spectrum potentially induced by disorder. Using a cavity for impedance enhancement, or a stack of few layer nanoribbons, these values can reach almost 100%. This opens a potential prospect of employing graphene ribbon structures as efficient polarizers in the far IR and THz frequencies.Comment: Revised version. 10 pages, 7 figure

Tunable graphene-based polarizer

It is shown that an attenuated total reflection structure containing a graphene layer can operate as a tunable polarizer of the electromagnetic radiation. The polarization angle is controlled by adjusting the voltage applied to graphene via external gate. The mechanism is based on the resonant coupling of $p-$polarized electromagnetic waves to the surface plasmon-polaritons in graphene. The presented calculations show that, at resonance, the reflected wave is almost 100% $s-$polarized.Comment: submitted to the Applied Physics Letter

Mechanism for graphene-based optoelectronic switches by tuning surface plasmon-polaritons in monolayer graphene

It is shown that one can explore the optical conductivity of graphene, together with the ability of controlling its electronic density by an applied gate voltage, in order to achieve resonant coupling between an external electromagnetic radiation and surface plasmon-polaritons in the graphene layer. This opens the possibility of electrical control of the intensity of light reflected inside a prism placed on top of the graphene layer, by switching between the regimes of total reflection and total absorption. The predicted effect can be used to build graphene-based opto-electronic switches.Comment: 5 page

Graphene-based polaritonic crystal

It is shown that monolayer graphene deposited on a spatially-periodic gate behaves as a polaritonic crystal. Its band structure depending on the applied gate voltage is studied. The scattering of electromagnetic radiation from such a crystal is presented calculated and analyzed in terms of Fano-type resonances between the reflected continuum and plasmon-polariton modes forming narrow bands.Comment: submitted to Phys. Rev. Let

Комп'ютерне проектування відсіків технічних поверхонь у навчальному процесі дизайнерів

Educational geometrical methods of automated designing of kinematic surfaces of the moldboards, realised in the form of computing programs that allow you to change the initial parameters of the pas, and explore the varied form of working surfaces of shelves, as well as getting in numerical or graphical form necessary to find solutions of variant information are considered.Рассматриваются учебные геометрические алгоритмы автоматизированного проектирования кинематических поверхностей полок, реализованые в виде вычислительных программ, которые позволяют изменять исходные параметры, варьировать и исследовать форму рабочих поверхностей полок, а также получать в численном или графическом виде необходимую для поиска вариантных решений информацию.Розглядаються навчальні геометричні алгоритми автоматизованого проектування кінематичних поверхонь полиць, реалізовані у вигляді обчислюваних програм, які дозволяють змінювати вихідні параметри, варіювати та досліджувати форму робочих поверхонь полиць, а також отримувати в чисельному чи графічному вигляді необхідну для пошуку варіантних рішень інформацію

Excitation of localized graphene plasmons by a metallic slit

In this paper we show that graphene surface plasmons can be excited when an electromagnetic wave packet impinges on a single metal slit covered with graphene. The excitation of the plasmons localized over the slit is revealed by characteristic peaks in the absorption spectrum. It is shown that the position of the peaks can be tuned either by the graphene doping level or by the dielectric function of the material filling the slit. The whole system forms the basis for a plasmonic sensor when the slit is filled with an analyte.The authors are grateful for useful discussions with H. Crespo. The authors acknowledge support from the European Commission through the project "Graphene-Driven Revolutions in ICT and Beyond" (Ref. No. 881603), and the Portuguese Foundation for Science and Technology through the Strategic Funding UID/FIS/04650/2019. Additionally, the authors acknowledge financing from FEDER and the Portuguese Foundation for Science and Technology (FCT) through Project No. POCI-01-0145-FEDER-028114