Suchergebnisse

Se analiza una situación histórica, en la cual una decisión política termina por afectar profundamente la capacidad de un ejército. De fondo, se estudia la necesidad de mantener políticas de desarrollo permanente de los ejércitos en todos sus aspectos, tanto en la guerra como en los tiempos de paz. Justamente porque dada la imposibilidad de predecir el futuro incierto, un Estado debe, en principio, mantener una actitud vigilante en lo que respecta a su capacidad de defensa. Este es el caso de Inglaterra y su decisión de detener en el periodo de entreguerras el proceso de desarrollo de la tecnología militar, los cambios doctrinales y organizativos, de acuerdo con nuevas circunstancias.

En la era de la información intervienen un conjunto de sistemas de información y comunicaciones en un proceso articulado a partir de la recolección de datos por sensores satelitales, aeronaves, el monitoreo y sistemas de cómputo y vigilancia. En medio de este complejo tecnológico, se abre paso el nuevo campo del combate virtual, ya no como aquella extensión de espacio propicia para enfrentar al enemigo con determinada cantidad de tropa, equipo y capacidades suficientes para tal fin. Ahora, se presenta como un territorio de carácter virtual.

In Colombia, strict humanitarian reasons alleviated the horror and excesses of the violence, achieving the validity of international law of armed conflicts in an uncertain and complex operational environment. Operational law emerges as a strength to the missions deployed by the military force, complementing the transition towards a culture of peace, complying with the demands of international organizations, while articulating a constructivist notion to contribute to the reduction of violence and legitimizing more and more peaceful methods as a way out of conflict. However, the new threats accompanied by countless instability factors make it difficult to understand them and make it difficult to apply operational procedures and the actions of the security forces. Warning where the urgency is created to educate the military population much better in the application of national and international legal regulations for this purpose, since even the justum bellum theory does not offer clear answers in the justification of these new forms of armed conflict. ; En Colombia, las estrictas razones humanitarias aliviaron el horror y los excesos de la violencia hasta lograr la vigencia del Derecho Internacional de los Conflictos Armados (DICA), en un ambiente operacional incierto y complejo. El derecho operacional surge como fortaleza y complemento en las misiones desplegadas por las Fuerzas Militares y la transición hacia la cultura de la paz, cumpliendo con las exigencias de los organismos internacionales en articulación con una noción constructivista para coadyuvar a la reducción de la violencia y legitimar cada vez más los métodos pacíficos como salida al conflicto. Sin embargo, las nuevas amenazas, acompañadas de un sinnúmero de factores de inestabilidad, dificultan su entendimiento y entorpecen la aplicación de los procedimientos operacionales junto al accionar de la fuerza pública. En este sentido, se crea la urgencia de educar mucho mejor a la población castrense en cuanto a la aplicación de las normativas jurídicas nacionales e internacionales para tal fin, pues ni siquiera la teoría del justum bellum ofrece respuestas claras en la justificación de las nuevas formas de conflicto armado. ; Na Colômbia, razões humanitárias estritas atenuaram o horror e os excessos do violência, alcançando a validade do Direito Internacional dos Conflitos Armados em um ambiente operacional incerto e complexo. O Direito Operacional surge como uma força para as missões destacadas pelas Forças Militares, complementando a transição para uma cultura de paz, atendendo às demandas das organizações internacionais e articulando uma noção construtivista para contribuir para a redução da violência e legitimação de métodos cada vez mais pacíficos como saída do conflito. No entanto, as novas ameaças, acompanhadas de vários fatores de instabilidade, dificultam sua compreensão, dificultando a aplicação de procedimentos operacionais e ações das forças de segurança. Advertindo onde a urgência é criada para educar a população militar muito melhor na aplicação dos regulamentos legais nacionais e internacionais para esse fim, uma vez que nem mesmo a teoria da justum bellum oferece respostas claras para justificar essas novas formas de conflito armado.

We consider a periodic chain of oscillating dipoles, interacting via long-range dipole–dipole interactions, embedded inside a cuboid cavity waveguide. We show that the mixing between the dipolar excitations and cavity photons into polaritons can lead to the appearance of new states localized at the ends of the dipolar chain, which are reminiscent of Tamm surface states found in electronic systems. A crucial requirement for the formation of polaritonic Tamm states is that the cavity cross section is above a critical size. Above this threshold, the degree of localization of the Tamm states is highly dependent on the cavity size since their participation ratio scales linearly with the cavity cross-sectional area. Our findings may be important for quantum confinement effects in one-dimensional systems with strong light–matter coupling. ; This work was supported by the Aragón government through the project Quantum Materials and Devices (Q-MAD) and Ministerio de Economía y Competitividad (MINECO) (Contract No. MAT2017-88358-C3-I-R). CAD acknowledges support from the Juan de la Cierva program (MINECO, Spain). ; Peer reviewed

A beam of linearly polarized light transmitted through magnetically biased graphene can have its axis of polarization rotated by several degrees after passing the graphene sheet. This large Faraday effect is due to the action of the magnetic field on graphene's charge carriers. As deformations of the graphene membrane result in pseudomagnetic fields acting on the charge carriers, the effect of random mesoscopic corrugations (ripples) can be described as the exposure of graphene to a random pseudomagnetic field. We aim to clarify the interplay of these typically sample inherent fields with the external magnetic bias field and the resulting effect on the Faraday rotation. In principle, random gauge disorder can be identified from a combination of Faraday angle and optical spectroscopy measurements. ; The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 604391 Graphene Flagship, from the European Research Council through Grant No. 290846, and from the Ministerio de Economía y Competitividad (MINECO), Spain under Projects No. MAT2014-53432-C5-1-R and No. FIS2014-207432. ; Peer Reviewed

4 páginas, 3 figuras.-- PACS numbers: 41.20.Jb, 42.25.Fx, 42.79.Ag.-- et al. ; We investigate band formation in one-dimensional periodic arrays of rectangular holes which have a nanoscale width but a length of 100 μm. These holes are tailored to work as resonators in the terahertz frequency regime. We study the evolution of the electromagnetic response with the period of the array, showing that this dependence is not monotonic due to both the oscillating behavior of the coupling between holes and its long-range character. ; The experimental work was supported by the Korea Science and Engineering Foundation (KOSEF) (SRC, No. R11-2008-095-01000-0), the Korea Research Foundation (KRF), KICOS (GRL, K20815000003), Hi Seoul Science/Humanities grant funded by the Korea government (MEST) (No. 2009-0071309), the Seoul R&BD Program (10543), and Seoul Scholarship Foundation. The theory work was funded by the Spanish Ministry of Science and Innovation under Projects No. MAT2008- 06609-C02, No. CSD2007-046-NanoLight.es, and by Grant No. RyC-2009-05489. ; Peer reviewed

9 páginas, 4 figuras. ; The role of Dyakonov surface waves in the transmission through structures composed of birefringent media is theoretically explored. In the case of structures using prisms, unexpected high transmission above the critical angle due to resonant excitation of Dyakonov surface waves is predicted. This transmission is produced only when TE polarized incident wave reaches the interface supporting the surface waves within a narrow interval of angles, for both the angle of incidence and the angle with respect to the optic axis of the birefringent media. As a result, over 90% transmission for a single and isolated peak confined in the two transversal directions, with hybrid TE and TM polarization, can be obtained. ; This work is supported by the Generalitat de Catalunya (2009-SGR-159) and the Ministry of Science and Innovation, Government of Spain (grant FIS2009-09928). ; Peer reviewed

Studying the collective excitations in charge neutral graphene (CNG) has recently attracted a great interest because of unusual mechanisms of the charge carrier dynamics. The latter can play a crucial role for formation of recently observed in twisted bilayer CNG graphene plasmon polaritons (GPPs) associated with the interband transitions between the flat electronic bands. Besides, GPPs in CNG can be a tool providing insights into various quantum phenomena in CNG via optical experiments. However, the properties of interband GPPs in CNG are not known, even in the simplest configurations. Here, we show that magnetically-biased single-layer CNG can support interband GPPs of both transverse magnetic and transverse electric polarizations (particularly, at zero temperature). GPPs exist inside the absorption bands originating from the electronic transitions between Landau levels and are tunable by the magnetic field. We place our study into the context of potential near-field and far-field optical experiments. ; We acknowledge funding from Spain's MINECO under Grant No. MAT2017-88358-C3 and funding from the European Union Seventh Framework Programme under grant agreement no. 881603 Graphene Flagship for Core 3 . L.M.M. acknowledge Aragon Government through project Q-MAD. A.Y.N. acknowledges the Basque Department of Education (grant numbers PIBA-2020-1-0014). The research for A.B.K. was supported by the Swiss National Science Foundation. ; Peer reviewed

We analyze the properties of strongly coupled excitons and photons in systems made of semiconducting two-dimensional transition-metal dichalcogenides embedded in optical cavities. Through a detailed microscopic analysis of the coupling, we unveil novel, highly tunable features of the spectrum that result in polariton splitting and a breaking of light-matter selection rules. The dynamics of the composite polaritons is influenced by the Berry phase arising both from their constituents and from the confinement-enhanced coupling. We find that light-matter coupling emerges as a mechanism that enhances the Berry phase of polaritons well beyond that of its elementary constituents, paving the way to achieve a polariton anomalous Hall effect. ; A. G.-R., L. M.-M., and F. G. acknowledge the European Commission under the Graphene Flagship, Contract No. CNECTICT-604391. L. C. and F. G. acknowledge funding from the European Union's Seventh Framework Program (FP7/2007-2013) through the ERC Advanced Grant NOVGRAPHENE (Grant Award No. 290846), and L. C. acknowledges the Comunidad deMadrid through Grant No. MAD2D-CM, S2013/MIT-3007. L. M.-M. and F. J. G.-V. acknowledge financial support by the Spanish MINECO under Contract No. MAT2014-53432-C5. ; Peer reviewed

This article is available under the terms of the Creative Commons Attribution 3.0 License. ; Here, we introduce the concept of magnetic localized surface plasmons (LSPs), magnetic dipole modes that are supported by cylindrical metal structures corrugated by very long, curved grooves. The resonance wavelength is dictated by the length of the grooves, allowing us to tune it to values much larger than the size of the particle. Moreover, magnetic LSPs also exist for extremely thin metal disks and, therefore, they could be used to devise metasurfaces with magnetic functionalities. Experimental evidence of the existence of these magnetic LSPs in the microwave regime is also presented, although the concept is very general and could be applied to terahertz or infrared frequencies. ; This work was supported in part by the European Research Council (ERC-2011-AdG proposal No. 290981) and the Spanish government (Grants No. CSD2007-0046- Nanolight.es and No. MAT2011-28581-C02). We also acknowledge financial support by the National Science Foundation of China (Grants No. 60990320, No. 60990321, No. 60990324, No. 61171024, No. 61171026, and No. 61138001), by the National High Tech (863) Projects (No. 2012AA030402 and No. 2011AA010202), and by the 111 Project (No. 111-2-05). ; Peer Reviewed

Vibrational ultrastrong coupling, where the light–matter coupling strength is comparable to the vibrational frequency of molecules, presents new opportunities to probe the interactions between molecules and zero-point fluctuations, harness cavity-modified chemical reactions and develop novel devices in the mid-infrared spectral range. Here we use epsilon-near-zero nanocavities filled with a model polar medium (SiO2) to demonstrate ultrastrong coupling between phonons and gap plasmons. We present classical and quantum-mechanical models to quantitatively describe the observed plasmon–phonon ultrastrong coupling phenomena and demonstrate a modal splitting of up to 50% of the resonant frequency (normalized coupling strength η > 0.25). Our wafer-scale nanocavity platform will enable a broad range of vibrational transitions to be harnessed for ultrastrong coupling applications. ; This research was supported by grants from the US National Science Foundation (ECCS 1809240 to D.Y., D.A.M., S.-H.O.; ECCS 1809723 to I.-H.L., S.-H.O.) and the Samsung Global Research Outreach (GRO) Program (to S.-H.O.). F.d.L.-P. and L.M.-M. acknowledge financial support from the Spanish Ministry of Economy and Competitivity through projects MAT2017-88358-C3-1-R and MAT2017-88358-C3-2-R and the Aragón Government project Q-MAD. M.P. acknowledges support from the US National Science Foundation (NSF DMR-1905135). M.B.R. acknowledges funding from the US National Science Foundation (NSF CHE-1709822). J.D.C. was supported by the Office of Naval Research Grant N00014-18-12107. S.-H.O. further acknowledges support from the Sanford P. Bordeau Chair in Electrical Engineering at the University of Minnesota. ; Peer reviewed

In recent years, enhanced light-matter interactions through a plethora of dipole-type polaritonic excitations have been observed in two-dimensional (2D) layered materials. In graphene, electrically tunable and highly confined plasmon-polaritons were predicted and observed, opening up opportunities for optoelectronics, bio-sensing and other mid-infrared applications. In hexagonal boron nitride, low-loss infrared-active phonon-polaritons exhibit hyperbolic behaviour for some frequencies, allowing for ray-like propagation exhibiting high quality factors and hyperlensing effects. In transition metal dichalcogenides, reduced screening in the 2D limit leads to optically prominent excitons with large binding energy, with these polaritonic modes having been recently observed with scanning near-field optical microscopy. Here, we review recent progress in state-of-the-art experiments, and survey the vast library of polaritonic modes in 2D materials, their optical spectral properties, figures of merit and application space. Taken together, the emerging field of 2D material polaritonics and their hybrids provide enticing avenues for manipulating light-matter interactions across the visible, infrared to terahertz spectral ranges, with new optical control beyond what can be achieved using traditional bulk materials. ; T.L. acknowledges financial support by DARPA grant award FA8650-16-2-7640. A.C. acknowledges support by CNPq, through the PRONEX/FUNCAP and Science Without Borders programs. J.D.C. acknowledges financial support from the Office of Naval Research that was administered by the NRL Nanoscience Institute. A.K. and N.X.F. acknowledge the financial support by AFOSR MURI (Award No. FA9550-12-1-0488). L.M.M. acknowledges the Spanish Ministry of Economy and Competitiveness under project MAT2014-53432-C5-1-R. F.K. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through the 'Severo Ochoa' Programme for Centres of Excellence in R&D (SEV-2015-0522), support by Fundacio Cellex Barcelona, the European Union H2020 Programme under grant agreement no 604391 Graphene Flagship', the ERC starting grant (307806, CarbonLight), and project GRASP (FP7-ICT-2013-613024-GRASP). ; Peer Reviewed

Photonic crystals (PCs) are periodically patterned dielectrics providing opportunities to shape and slow down the light for processing of optical signals, lasing and spontaneous emission control. Unit cells of conventional PCs are comparable to the wavelength of light and are not suitable for subwavelength scale applications. We engineer a nanoscale hole array in a van der Waals material (h-BN) supporting ultra-confined phonon polaritons (PhPs)—atomic lattice vibrations coupled to electromagnetic fields. Such a hole array represents a polaritonic crystal for mid-infrared frequencies having a unit cell volume of 10−5λ30 (with λ0 being the free-space wavelength), where PhPs form ultra-confined Bloch modes with a remarkably flat dispersion band. The latter leads to both angle- and polarization-independent sharp Bragg resonances, as verified by far-field spectroscopy and near-field optical microscopy. Our findings could lead to novel miniaturized angle- and polarization-independent infrared narrow-band couplers, absorbers and thermal emitters based on van der Waals materials and other thin polar materials. ; The authors acknowledge financial support from the European Commission under the Graphene Flagship (GrapheneCore2), the Spanish Ministry of Economy and Competitiveness (national projects MAT2017-88358-C3,MAT 2015-65159-R, MAT2014-53432-C5, FIS2014-60195-JIN), the Basque government (PhD fellowship PRE-2016-1-0150) and the European Research Council under the starting grants SPINTROS (Grant no. 257654) and 2DNANOPTICA (Grant no. 715496). ; Peer reviewed

Launching and manipulation of polaritons in van der Waals materials offers novel opportunities for field-enhanced molecular spectroscopy and photodetection, among other applications. Particularly, the highly confined hyperbolic phonon polaritons (HPhPs) in h-BN slabs attract growing interest for their capability of guiding light at the nanoscale. An efficient coupling between free space photons and HPhPs is, however, hampered by their large momentum mismatch. Here, we show —by far-field infrared spectroscopy, infrared nanoimaging and numerical simulations— that resonant metallic antennas can efficiently launch HPhPs in thin h-BN slabs. Despite the strong hybridization of HPhPs in the h-BN slab and Fabry-Pérot plasmonic resonances in the metal antenna, the efficiency of launching propagating HPhPs in h-BN by resonant antennas exceeds significantly that of the non-resonant ones. Our results provide fundamental insights into the launching of HPhPs in thin polar slabs by resonant plasmonic antennas, which will be crucial for phonon-polariton based nanophotonic devices. ; The authors acknowledge financial support from the European Commission under the Graphene Flagship (GrapheneCore2), the Spanish Ministry of Science, Innovation and Universities (national projects MAT2017-88358-C3, MAT2015-65159-R, MAT2015-65525-R, RTI2018-094830-B-100, RTI2018-094861-B-100, and the project MDM-2016-0618 of the Marie de Maeztu Units of Excellence Program) the Marie Sklodowska-Curie individual fellowship (SGPCM-705960), the Basque Government (PhD fellowship PRE 2018 2 0253), and the project PIC201660E046 from CSIC. M.M.W. acknowledges support from the Konrad-Adenauer-Stiftung. P.A.G. acknowledges support from the European Research Council under Starting Grant 715496, 2DNANOPTICA. ; Peer reviewed

Integrating and manipulating the nano-optoelectronic properties of Van der Waals heterostructures can enable unprecedented platforms for photodetection and sensing. The main challenge of infrared photodetectors is to funnel the light into a small nanoscale active area and efficiently convert it into an electrical signal. Here, we overcome all of those challenges in one device, by efficient coupling of a plasmonic antenna to hyperbolic phonon-polaritons in hexagonal-BN to highly concentrate mid-infrared light into a graphene pn-junction. We balance the interplay of the absorption, electrical and thermal conductivity of graphene via the device geometry. This approach yields remarkable device performance featuring room temperature high sensitivity (NEP of 82 pW/Hz−−−√) and fast rise time of 17 nanoseconds (setup-limited), among others, hence achieving a combination currently not present in the state-of-the-art graphene and commercial mid-infrared detectors. We also develop a multiphysics model that shows very good quantitative agreement with our experimental results and reveals the different contributions to our photoresponse, thus paving the way for further improvement of these types of photodetectors even beyond mid-infrared range. ; F.H.L.K. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through the "Severo Ochoa" Programme for Centres of Excellence in R& D (SEV-2015-0522), support by Fundacio Cellex Barcelona, Generalitat de Catalunya through the CERCA program, and the Agency for Management of University and Research Grants (AGAUR) 2017 SGR 1656. Furthermore, the research leading to these results has received funding from the European Union Seventh Framework Programme under grant agreement no. 785219 and no. 881603 Graphene Flagship for Core2 and Core3. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). K.J.T. acknowledges funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 804349. R.H. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (national project RTI2018-094830-B-100 and the project MDM-2016-0618 of the Marie de Maeztu Units of Excellence Program) and the Basque Government (grant No. IT1164-19). S.C. acknowledges financial support from the Barcelona Institute of Science and Technology (BIST), the Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya and the European Social Fund (L'FSE inverteix en el teu futur)—FEDER. D.E. acknowledges partial support from the Army Research Office MURI "Ab-Initio Solid-State Quantum Materials" Grant No. W911NF18-1-0431. J.G. was supported by the ARL-MIT Institute for Soldier Nanotechnologies (ISN). T.S. and L.M.M. acknowledge support by Spain's MINECO under Grant No. MAT2017-88358-C3-1-R and the Aragon Government through project Q-MAD. ; Peer reviewed