Frequency gating to isolate single attosecond pulses with overdense plasmas using particle-in-cell simulations

We present the isolation of single attosecond pulses for multi-cycle and few-cycle laser pulses from high harmonic generation in overdense plasmas, calculated with particle-incell simulations. By the combination of two laser pulses of equal amplitude and a small frequency shift between them, we demonstrate that it is possible to shorten the region in which the laser pulse is most intense, therefore restricting the generation of high harmonic orders in the form of attosecond pulses to a narrower time window. The creation of this window is achieved due to the combination of the laser pulse envelope and the slow oscillating wave obtained from the coherent sum of the two pulses. A parametric scan, performed with particle-in-cell simulations, reveals how the pulse isolation behaves for different input laser pulse lengths and which are the optimal frequency shifts between the two laser pulses in each case, giving the conditions for having a good isolation of an attosecond pulse when working with laser-plasma interaction in overdense targets.European Union and the Spanish Ministry of Economy and Competitivity (MINECO) (MAT2015-71119-R AEI/FEDER); Xunta de Galicia/FEDER (Agrup2015/11 (PC034)); Spanish Ministry of Education, Culture and Sports (MECD) (FPU14/00289)S

Laser-based surface multistructuring using optical elements and the Talbot effect

We present a laser based technique combined with the Talbot effect for microstructuring surfaces. The use of the Talbot effect is introduced as a solution to avoid damage of the periodic object used for micropattering different surfaces during the ablation process. The fabrication of two periodic objects (a mask and a microlens array) for micropattering surfaces and the identification of their Talbot planes is presented. A metal foil is ablated at distances corresponding to selected Talbot planes of the periodic objects. The setup allows us to design the desired pattern and the result is a multistructured surface with a high number of identical microholes, achieving a minimum diameter around 4μm. The different aspect of the periodic object working in direct contact and working at these Talbot distances is shown. These pictures reveal the advantages of working of using Talbot effect for a rapid, repeatable and no-contaminant multistructuring. Some industrial applications are illustrated.This work has been supported by the Consellería de Cultura, Xunta de Galicia/FEDER, Spain under Contract EM2012/019S

Table-top laser-based proton acceleration in nanostructured targets

The interaction of ultrashort, high intensity laser pulses with thin foil targets leads to ion acceleration on the target rear surface. To make this ion source useful for applications, it is important to optimize the transfer of energy from the laser into the accelerated ions. One of the most promising ways to achieve this consists in engineering the target front by introducing periodic nanostructures. In this paper, the effect of these structures on ion acceleration is studied analytically and with multidimensional particle-in-cell simulations.Weassessed the role of the structure shape, size, and the angle of laser incidence for obtaining the efficient energy transfer. Local control of electron trajectories is exploited to maximize the energy delivered into the target. Based on our numerical simulations, we propose a precise range of parameters for fabrication of nanostructured targets, which can increase the energy of the accelerated ions without requiring a higher laser intensity.This work has been partially supported by the Xunta de Galicia/FEDER under contract Agrup2015/11 (PC034) and by MINECO under contracts MAT2015-71119-R and FIS2015-71933-REDT. The authors would like to acknowledge the OSIRIS Consortium, consisting of UCLA and IST (Lisbon, Portugal) for the use of OSIRIS, for providing access to the OSIRIS framework. M Blanco also thanks the Ministry of Education of the Spanish government for the FPU fellowship. Camilo Ruiz also thanks MINECO project FIS2016-75652-P M Vranic acknowledges the support of ERC-2010-AdG Grant 267841 and LASERLAB-EUROPE IV—GA No. 654148. Simulations were performed at the Accelerates cluster (Lisbon, Portugal)S

Laser Surface Microstructuring of Biocompatible Materials Using a Microlens Array and the Talbot Effect: Evaluation of the Cell Adhesion

A laser based technique for microstructuring titanium and tantalum substrates using the Talbot effect and an array of microlenses is presented. By using this hybrid technique; we are able to generate different patterns and geometries on the top surfaces of the biomaterials. The Talbot effect allows us to rapidly make microstructuring, solving the common problems of using microlenses for multipatterning; where the material expelled during the ablation of biomaterials damages the microlens. The Talbot effect permits us to increase the working distance and reduce the period of the patterns. We also demonstrate that the geometries and patterns act as anchor points for cells; affecting the cell adhesion to the metallic substrates and guiding how they spread over the materialThis work has been supported under contracts MAT2015-71119-R, Ministerio de Economía y Competitividad, and ISCIII/PI14-01140/FEDER, Instituto de Salud Carlos III, Spain. M. Aymerich acknowledges a Pre-Doctoral Fellowship from Xunta de Galicia (Spain) financed by the Secretaría Xeral de Universidades and the Fondo Social Europeo (FSE). D. Nieto thanks the Consellería de Cultura, Spain for their support under the Galician Programme for Research Innovation and Growth (2011–2015) (I2C Plan)S

Study of Different Sol-Gel Coatings to Enhance the Lifetime of PDMS Devices: Evaluation of Their Biocompatibility

A study of PDMS (polydimethylsiloxane) sol-gel–coated channels fabricated using soft lithography and a laser direct writing technique is presented. PDMS is a biocompatible material that presents a high versatility to reproduce several structures. It is widely employed in the fabrication of preclinical devices due to its advantages but it presents a rapid chemical deterioration to organic solvents. The use of sol-gel layers to cover the PDMS overcomes this problem since it provides the robustness of glass for the structures made with PDMS, decreasing its deterioration and changing the biocompatibility of the surface. In this work, PDMS channels are coated with three different kinds of sol-gel compositions (60MTES/40TEOS, 70MTES/30TISP and 80MTES/20TISP). The endothelial cell adhesion to the different coated devices is evaluated in order to determine the most suitable sol-gel preparation conditions to enhance cellular adhesion.This work has been supported under contracts MAT2015–71119-R, Ministerio de Economíay Competitividad, and ISCIII/PI14-01140/FEDER, Instituto de Salud Carlos III, Spain. M. Aymerich acknowledges a Pre-Doctoral Fellowship from Xunta de Galicia (Spain) financed by the Sistema Universitario de Galicia (SUG) and the Fondo Social Europeo (FSE)S

Control de filtros oftálmicos solares

En este trabajo se pretende reunir información acerca de los filtros oftálmicos solares y hacer un breve resumen de la legislación que los ampara en nuestro país. Se divide principalmente en dos bloques: El primer bloque es más teórico y en él se trata por un lado, como ha evolucionado en el tiempo la gafa de sol y su uso, así como los distintos problemas que causa en nuestra salud ocular no protegernos correctamente de la luz solar y las distintas radiaciones que la forman. Por otro lado describe la normativa española por la que se rigen las gafas de sol que hay en el mercado hoy en día. Se pretende resumir y agrupar las distintas leyes de manera que en el futuro pueda utilizarse como un manual de consulta que aclare cualquier duda sobre este tema de manera rápida y eficaz. El segundo bloque es un estudio realizado en el que se pretende buscar diferencias entre los diferentes filtros que encontramos en el mercado. Se separaron los filtros en tres categorías diferentes siendo el principal criterio el tipo de establecimiento de venta de la gafa de sol. En el primer grupo encontramos gafas obtenidas en un establecimiento óptico, en el segundo grupo gafas obtenidas en tiendas de una cadena de moda española que vende a nivel internacional y en el tercer grupo gafas obtenidas en bazares y mercadillos. De cada grupo se midieron 50 gafas completas (100 lentes) con el espectrómetro PerkinElmer precisly Lambda 25. Tras medir la transmitancia de cada filtro se procedió a analizar los datos para compararlos y comprobar si todos ellos cumplían con la normativa

Phase matching effects in high harmonic generation at the nanometer scale

Plasmon resonances are known to amplify the electromagnetic fields near metallic nanostructures, providing a promising scheme to generate extreme-ultraviolet harmonics using low power drivings. During high-order harmonic generation (HHG), the driving and harmonic fields accumulate a phase di erence as they propagate through the target. In a typical set-up –a laser focused into a gas jet– the propagation distances amount to several wavelengths, and the cumulative phase-mismatch a ects strongly the e ciency and properties of the harmonic emission. In contrast, HHG in metallic nanostructures is considered to overcome these limitations, as the common sources of phase mismatch –optical density and focusing geometry– are negligible for subwavelength propagation distances. We demonstrate that phase matching still plays a relevant role in HHG from nanostructures due to the non-perturbative character of HHG, that links the harmonic phase to the intensity distribution of the driving field. Our computations show that widely used applications of phase matching control, such as quantum path selection and the increase of contrast in attosecond pulse generation, are also feasible at the nanoscale.Junta de Castilla y León (SA046U16) and MINECO (FIS2013-44174-P, FIS2016-75652-P, FIS2015-71933-REDT, SEV-2015-0522, FIS2013-46768-P, FIS2016-79508-P). M. Blanco is funded by FPU grant program of MECD. C. H.-G. is funded by Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007-2013), grant Agreement No. 328334. A. Chacón and M. Lewenstein also acknowledge support from Adv. ERC grant OSYRIS, Generalitat de Catalunya (SGR 874, CERCA Program), and Fundació Privada CellexS

Microfluidic devices manufacturing with a stereolithographic printer for biological applications

Stereolithographic printers have revolutionized many manufacturing processes with their capacity to easily produce highly detailed structures. In the field of microfluidics, this technique avoids the use of complex steps and equipment of the conventional technologies. The potential of low force stereolithography technology is analysed for the first time using a Form 3B printer and seven printing resins through the fabrication of microchannels and pillars. Manufacturing performance of internal and superficial channels and pillars is studied for the seven printing resins in different configurations. A complete characterization of printed structures is carried out by optical, confocal and SEM microscopy, and EDX analysis. Internal channels with unobstructed lumen are obtained for diameters and angles greater than 500 μm and 60°, respectively. Outward and inward superficial channels in the range of hundreds of microns can be fabricated with an accurate profile, printing them with a perpendicular orientation respect to the base, allowing a proper uncured resin evacuation. Outward channels are replicated by soft lithography using polydimethylsiloxane. Clear, Model and Tough resins show a good behaviour to be used as master, but Amber and Dental resins present a poor topology transference from the master to the replica. According to the needs of devices used for biological and biomedical research, transparency as well as superficial biocompatibility of some resins is evaluated. Human umbilical vein endothelial cells (HUVEC) adhesion is confirmed on Amber, Dental and Clear resins, but these cells were only able to grow and progress as a cell culture over the Amber resin. Therefore, Amber showed an adequate biocompatibility, in terms of cell adhesion and growth for HUVECAuthors gratefully thank contracts AEI RTI2018-097063-B-100, AEI/FEDER, UE; ED431B 2020/29; ED431E 2018/08 and ED481D-2021-019, Consellería de Educación Xunta de Galicia/FEDER e Estructuración Xunta de Galicia, IN607A2019-02 and Sociedad española de cardiología y Fundación español del corazón, SEC/FEC-INV-BAS 20/013S

Internal Microchannel Manufacturing Using Stereolithographic 3D Printing

Internal channels are one of the most interesting structures to implement in microfluidics devices. Unfortunately, the optical technologies typically used in microfluidics, such as photolithography or reactive ion etching, are unable to generate these structures by only allowing surface structuring. Stereolithographic 3D printing has emerged as a very promising technology in internal microchannel manufacturing, by allowing a layer-by-layer structuring in volume performed by a laser that photopolymerises a liquid resin. Recent advances in laser technologies have reached resolutions of tens of micrometres. The high resolution of this type of printer, which a priori would allow the fabrication of channels of the same dimensions, may pose a problem by impeding the evacuation of uncured resin. In this chapter, the compromise between size and resin evacuation will be evaluated to find the optimal diameter range in which unobstructed and accurate microchannels can be obtained