Optical and magneto-optical properties of Au:Conanoparticles and Co:Aunanoparticles doped magnetoplasmonic systems

© 2015 AIP Publishing LLC. We report a study of Au:CoNPs and Co:AuNPs doped magnetoplasmonic systems. In particular, we analyze the effect of adding different concentrations of Co (or Au) nanoparticles (NPs) in a Au (or Co) matrix on both the optical and magneto-optical constants. Through the use of a simple effective medium model, relevant changes in the optical properties of the Au NPs compared to those of bulk material have been identified. Such effects are not observed in the Co NPs system. However, in both systems, there is an increase of the effective diameter of the NPs as compared to the real diameter that can be due to interface effects surrounding the NPs. Moreover, the magneto-optical constants values of both systems are smaller (in absolute values) than expected, which could also be attributed to interface effects such as hybridization between Au and Co.This work was supported by the Spanish MINECO under Project Nos. MAT2011-29194-C02 (MAPS), CSD2007-00041 (NANOSELECT), and CSD2008-00023 (FUNCOAT). http://dx.doi.org/10.1063/1.4906946Peer Reviewe

Theoretical analysis of magnetoplasmonic interferometers for sensing

Comunicación presentada en la Conferencia Española de Nanofotónica (CEN2012), celebrada en Carmona (Sevilla) del 1 al 4 de octubre de 2012.Peer Reviewe

Plasmonic and magnetoplasmonic interferometry for sensing

[Introduction and background] Nowadays, we are surrounded by sensors in our daily lives, in industrial processes, medical diagnosis systems, environmental monitoring, etc. The development of sensors with higher sensitivity and smaller dimensions to be integrated in miniaturized systems is then of highest importance for our society. Within all different kinds of sensors, optical sensors are advantageous because they are highly versatile, non-invasive and they can be used in aggressive conditions. In particular, sensors based on surface plasmons, known as surface plasmon resonance (SPR) sensors, have become increasingly popular in biosensing in recent decades due to their high sensitivity and ease of use. Different SPR configurations, such as modulation techniques, have been proposed and demonstrated in order to increase their sensitivity, and attempts to obtain miniaturized SPR sensors have been carried out, the development of plasmonic interferometry sensors being a promising path.[Main results] We have compared theoretically the performance of three implementations of plasmonic sensors: the standard SPR configuration, plasmonic interferometry and magnetically modulated plasmonic (magnetoplasmonic) interferometry. Our results show that the sensitivity of plasmonic interferometers surpasses that of standard SPR methods for long enough except the micrometer-sized interferometers. Moreover, when plasmonic interferometers are magnetically modulated, the direct measurement of the induced modulation in the surface plasmon wavevector allows one to further increase the system sensitivity.[Wider implications] These results show that the development of plasmonic interferometers for sensing, either plain or magnetically modulated, is an interesting route to obtain miniaturized surface plasmon based sensors with higher sensitivity. Moreover, the extended knowledge of immobilization protocols in gold already developed for standard SPR sensors will remain applicable.We acknowledge funding from the Spanish MINECO ('MAPS' MAT2011-29194-C02-01 and 'FUNCOAT' CONSOLIDER INGENIO 2010 CSD2008-00023) and the Comunidad de Madrid ('MICROSERES-CM' S2009/TIC-1476).Peer Reviewe

Magnetoplasmonic Interferometers and Applications

Comunicación presentada en el 2nd Early Stage Researchers Workshop in Nanoscience, celebrado en Madrid el 28 y 29 de junio de 2012.Surface plasmons polaritons (SPP) are evanescent waves that propagate along a dielectric-metal interface. They can be confined in subwavelength metal structures, i.e. below the diffraction limit, which leads to many possible applications, including miniaturized optical devices. Within that context, the development of active plasmonics is important to achieve nanophotonic devices with advanced functionalities. This requires a system where the plasmon properties can be manipulated using an external agent. Among the different control agents considered so far, the magnetic field seems a promising candidate, since it is able to modify the dispersion relation of SPP at reasonable magnetic field strengths, and with a high switching speed. This modulation comes from the non-diagonal elements of the dielectric tensor, εij, appearing when the magnetic field is turned on. For noble metals, the ones typically used in plasmonics, these elements are proportional to the applied magnetic field but, unfortunately, very small at field values reasonable for developing applications. On the other hand, ferromagnetic metals have sizeable εij values at small magnetic fields (proportional to their magnetization), but are optically too absorbent. A smart system to develop magnetic field tunable plasmonic devices is the use of multilayers of noble and ferromagnetic metals. That is the framework of the present work, where we analyze the magnetic field induced SPP wavevector modulation (Ak) in Au/Co/Au films as a function of the wavelength and its possible application as a sensor.N

Magnetoplasmonics: Combining Magnetic and Plasmonic Functionalities

Comunicación presentada en el 3rd European Workshop on Self Organized Nanomagnets, celebrado en Guadarrama del 16 al 20 de abril de 2012.Nanosystems with combined magnetic and plasmonic functionalities have in recent years become an active topic of research. In these new stn-lctures, know as magneto-plasmonics, magnetic and plasmonic properties are interlwined, allowing for example plasmonic properties to become tunable upon de application of a magnetic field (active plasmonics), or the Magneto*Optical (MO) effects to be largely increased by plasmon resonance excitation, as a consequence of the enhancement of the electromagnetic (EM) field in the MO active component of the structure. ln this last case, the study of the enhanced MO activity in structures with subwavelength dimensions is especially interesting since they may be viewed as nanoantennas in the visible range with MO functionalities. The light harvesting properties of these systems upon plasmon resonance excitation bring as a consequence an enhanced EM field in its interior, and more interestingly in the region where the MO active component is present. At this stage, optimizing the EM field distribution within the structure by maximizing it in the MO components region while simultaneously minimizingit in all the other, non MO active, lossy components, will allow for the development of novel systems with even larger MO activity with reduced optical losses .Peer Reviewe

Catálogo de variedades de yuca, Cauca - Colombia

El presente catálogo de variedades de yuca representa la diversidad del cultivo en el departamento del Cauca, Colombia. En él, se han resumido las 28 variedades criollas y mejoradas como una guía de las mejores variedades disponibles en la región; para suplir las demandas de las rallanderias por almidón panificable. Cada variedad tiene descritas las características morfológicas, agronómicas, área y rendimiento reportado por agricultores y adicionalmente un código genético basado en marcadores moleculares tipo SNP

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Active Plasmonic Devices: Based on Magnetoplasmonic Nanostructures

This thesis investigates the effect of the magnetic field on propagating surface plasmon polaritons (SPPs), or surface plasmons for short. Above all, it focuses on using the magnetic field as an external agent to modify the properties of the SPPs, and therefore achieving active devices. Surface plasmons are evanescent waves that arise at metal–dielectric interfaces. They can be strongly confined (beyond the light diffraction limit), and provide a strong enhancement of the electromagnetic field at the interface. These waves have led to the development of plasmonic circuitry, which is a key candidate as an alternative to electronic circuitry and traditional optical telecommunication devices, since it is faster than the former and less bulky than the latter. Adopting both a theoretical and an experimental point of view, the book analyzes the magnetic modulation in SPPs by means of an interferometer engraved in a multilayer combining Au and Co. In this interferometer, which acts like a modulator, the SPP magnetic modulation is studied in detail, as are the parameters that have a relevant impact on it, simple ways to enhance it, its spectral dependence, and the highly promising possibility of using this system for biosensing. The thesis ultimately arrives at the conclusion that this method can provide values of modulations similar to other active methods used in plasmonics.I want to acknowledge the financial help of the International Iberian Nanotechnology Laboratory, as well as the different projects in which I have take part: • Optical microsystems Resonant Sensors (MICROSERES) from the Comunidad de Madrid • Magnetoplasmonics: hybrid nanostructures with magnetic and plasmonic properties from MICINN • NANOstructured active MAGneto-plasmonic MAterials—NANOMAGMA (NMP3-SL-2008-214107) from EU • Magneto-optically Active Plasmonic Systems (MAPS) from MICINNPeer reviewe

Desarrollo de dispositivos plasmónicos activos basados en nanoestructuras magnetoplasmónicas

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Óptica, leída el 26-03-2015En esta tesis se ha estudiado y analizado en profundidad el efecto de un campo magnético en plasmones propagantes de superficie, usando la estructura metálica Au/ Co/Au. Este análisis se ha llevado a cabo mediante un dispositivo activo, en particular en un interferómetro plasmónico que actúa como un modulador; pues al aplicar el campo magnético el vector de onda va a verse modificado, y en consecuencia habremos modulado también el patrón de interferencia del interferómetro. Este análisis ha sido realizado tanto experimentalmente como teóricamente. Por ejemplo se han litografiado mediante ¿Haz de iones focalizado¿ (FIB) los interferómetros, también se ha realizado el montaje óptico y magnético especial con su correspondiente automatización para la medida de la modulación magnética. Además se han caracterizado todas las muestras tanto óptica como magnéticamente mediante elipsometría y espectros kerr polares y transversales, se ha visto su topografía mediante AFM cuando ha sido necesario¿ El estudio teórico se ha hecho mediante el método de matriz de ¿dispersión¿, y analíticamente cuando ha sido posible.En concreto, hemos estudiado la dependencia de la modulación magnética de los plasmones con los distintos parámetros implicados en el interferómetro, como por ejemplo la estructura de la tricapa o las constantes magnetoópticas, así como la dependencia espectral y las posibilidades de aumentar dicha modulación magnética de manera sencilla. También se ha explorado la capacidad sensora de estos interferómetros modulados con un campo magnético y se han comparado con los conocidos sensores de resonancia de plasmón, llamados SPR. Finalmete, debido a la naturaleza evanescente de los plasmones, hemos analizado el concepto de modulación magnética de los SPPs en el campo cercano, usando distintas configuraciones interferométricas. De este trabajo, se han obtenido cinco conclusiones globales:El interferómetro magnetoplasmónico es una herramienta muy interesante tanto para medir como para analizar la modulación magnética del vector de onda del plasmón. Además los parámetros que gobiernan esta modulación magnética están relacionados principalmente con las propiedades del plasmón, más que con las propiedades magnetoópticas del material ferromagnético. Es especialmente fundamental el papel de la distribución del campo electromagnético del plasmón a lo largo de los materiales que forman la intercara, estrechamente relacionado con su relación de dispersión y la separación de ésta respecto a la línea de la luz.El interferómetro magnetoplasmónico puede ser, además, un dispositivo en sí mismo. Es una opción viable a la hora de modular de forma activa el plasmón. Hemos visto que aplicando campos magnéticos moderados ($20$ mT) obtenemos valores de modulaciones de intensidad de en torno al 2% en tricapas Au/Co/Au sin optimizar, en interferómetros del orden de decenas de micras. Además, podríamos obtener modulaciones de intensidad del 12% cambiando Fe por Co, trabajando a unos 950 nm y cubriendo el interferómetro con un dieléctrico con un índice de refracción n=1.49.Además, el interferómetro plasmónico es muy interesante también como biosensor, y puede ser más sensible que los tradicionales sensores de SPR. El interferómetro magnetoplasmónico, además, presenta la oportunidad de utilizar la modulación magnética del plasmón como nuevo parámetro sensor, siendo esta más sensible a cambios en el índice de refracción.Finalmente, del análisis en el campo cercano hemos visto que eligiendo diferentes configuraciones, podríamos tener acceso no solo a la modulación del vector de onda del plasmón, sino también a la componente vertical del mismo y a su correspondiente modulación magnética.Depto. de ÓpticaFac. de Ciencias FísicasTRUEunpu