Distributed feedback lasers based on perylenediimide dyes for label-free refractive index sensing

The refractive index sensing capabilitity of distributed feedback (DFB) lasers based on highly photostable (under ambient conditions) perylenediimide-based active films, are reported. The sensor bulk sensitivity is determined from changes in the laser emission wavelength upon exposure to different liquids. The role of the active film thickness (hf) on the sensor sensitivity and on the laser parameters is studied. Sensors based on very thin films (hf = 160 nm) show the highest sensitivities, but their laser thresholds are relatively high and their operational durabilities moderate. The use of thicker films (hf = 850 nm) allows reducing the laser threshold and increasing the durability by two orders of magnitude. In this case, a higher sensitivity is achieved when the sensor operates at the wavelength corresponding to the first-order TE1 mode, instead of at the TE0 one. Finally, it is also shown that the inclusion of a high refractive index TiO2 layer on top of the sensor structure improves the sensitivity by around two times.This work was supported by the Spanish Government (MINECO) and the European Community (FEDER) through grant no. MAT-2011–28167-C02. This work was partially funded by the Basque Government within the framework of the Etortek Program (Grant No. IE13-360). M. Morales-Vidal has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747)

Perylenediimide-based distributed feedback lasers with holographic relief gratings on dichromated gelatine

One dimensional second-order distributed feedback (DFB) lasers consisting of polystyrene (PS) films doped with a perylenediimide laser dye, deposited over dichromated gelatine (DCG) photoresist layers with solvent resistant relief gratings recorded by holographic lithography, are reported. The advantage of using the grating on DCG in the final device is that the fabrication process is simplified and the grating pattern better preserved, since no etching methods to transfer the grating to another substrate are needed. A very simple model, proposed to explain the experimental waveguide properties, has allowed identifying the waveguide mode at which DFB emission appears, which was the key to optimize the device performance. In the frame of this model, the thickness of the PS and DCG films could be adjusted in order to minimize the laser threshold and to control its wavelength tuneability. The performance of these lasers is comparable to that of recently reported devices based on the same active material, but deposited over high-quality DFB gratings engraved on SiO2 by nanoimprint lithography.We thank support from the Spanish Government (MINECO) and the European Community (FEDER) through Grant Nos. MAT2008-06648-C02 and MAT-2011-28167-C02, as well as to the University of Alicante. M.G.R. was supported by a CSIC fellowship within the program JAE

Two-dimensional distributed feedback lasers with thermally-nanoimprinted perylenediimide-containing films

Two-dimensional (2D) distributed feedback (DFB) lasers with gratings imprinted by thermal nanoimprint lithography on the active film are reported. They show thresholds for lasing of ∼10 kW/cm2, similar to the most efficient imprinted DFB lasers reported; and long operational lifetimes (under ambient conditions) of ∼12 × 104 pump pulses. The key for their successful operation has been the selection of a highly efficient and stable dye, perylene orange (PDI-O), and a proper matrix to host it, the fluoro-modified thermoplastic resist mr-I7030R, which has enabled 2D imprinting while preserving the dye optical properties. The use of the UV-curable resist SU8 as an alternative matrix for PDI-O to be imprinted by combined nanoimprint and photolithography was also investigated, and was concluded to be unsuccessful due to severe photoluminescence quenching. By replacing PDI-O with Rhodamine 6G, lasers with reasonable thresholds, but with significantly inferior operational lifetimes in comparison to PDI-O/mr-I7030R devices, were obtained.We thank support from the Spanish Government (MINECO) and the European Community (FEDER) through Grants MAT2011-28167-C02 and MAT2015-66586-R, as well as to the University of Alicante. M.M-V. has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747) and by a Junta de Castilla y León grant (no. SA046U16)

Improved performance of perylenediimide-based lasers

The aim of this work was to improve the laser performance, in terms of threshold and operational lifetime, of lasers based on polymer films doped with perylenediimide (PDI) derivatives as active media. For such purpose, we first investigated the amplified spontaneous emission (ASE) properties of perylene orange (PDI-O), when doped into polystyrene (PS) films. Lower ASE thresholds and larger photostabilities than those of similar films containing another PDI derivative (PDI-C6), recently reported in the literature, have been measured. Results have been interpreted in terms of the photoluminescence efficiency of the films, which depends on the type of molecular arrangement, inferred with the help of nuclear magnetic resonance experiments. We also show that PS films have a better ASE performance, i.e. lower thresholds and larger photostabilities, than those based on poly(methyl methacrylate), which was recently highlighted as one of the best matrixes for PDI-O. Finally, a one-dimensional second-order distributed feedback laser using PS doped with PDI-O was fabricated and characterized. This device has shown a threshold significantly lower (by around one order of magnitude) than that of a similar laser based on PDI-C6-doped PS.We thank support from the Spanish Government (MECC) and the European Community (FEDER) through grants MAT2008-06648-C02 and MAT-2011-28167-C02, as well as from the University of Alicante. MGR and MM are supported respectively by a CSIC fellowship within the program JAE and by MEC through a FPI fellowship

Traditions and innovations: versatility of copper and tin bronze making recipes in Iron Age Emporion (L’Escala, Spain)

Funder: Institute for Archaeometallurgical StudiesAbstractEstablished around 575 BC, Emporion was a Greek colonial enclave in north-east Iberia and hence constitutes a good context to study Mediterranean innovations and their adaptation with indigenous technologies. Here, we present an analytical study of the archaeometallurgical assemblage from a workshop context dated to the first occupational moment of Emporion’s Neapolis (second half of the sixth century BC), including slag and technical ceramics. We aimed at reverse engineering the copper and tin bronze metallurgical technologies at the site. The results allow the identification of copper smelting and melting, and a variety of bronze alloying techniques, together with iron smelting and forging. The use of Fe-rich copper ores with BaO, ZnO and PbO impurities is consistent with the exploitation of local sources, preceding the diversification of raw materials documented for later phases. The co-occurrence of co-smelting, cementation and co-melting as bronze making technologies is discussed with reference to parameters of efficiency and cost-effectiveness and contextualised in the broader colonial interaction, providing pointers for future comparative work and discussion. The early use of metallic tin for bronze production at the site supports a Mediterranean origin for this innovation in Iberia.</jats:p

Thermal-nanoimprint lithography for perylenediimide-based distributed feedback laser fabrication

In the present work thermal-nanoimprint lithography of various commercial thermoplastic resists as matrixes for perylenediimides (PDIs) has been studied. This fabrication method reduces the number of fabrication steps, and therefore, the cost of the obtained distributed feedback (DFB) lasers. The optical properties of these devices are analyzed, aiming to optimize their performance.Spanish Government (MINECO) and the European Community (FEDER) through grants MAT2008-06648-C02 and MAT-2011-28167-C02. Manuel G. Ramírez is supported by a CSIC fellowship within the program JAE

Impact of surface topography on the bacterial attachment to micro- and nano-patterned polymer films

The development of antimicrobial surfaces has become a high priority in recent times. There are two ongoing worldwide health crises: the COVID-19 pandemic provoked by the SARS-CoV-2 virus and the antibiotic-resistant diseases provoked by bacteria resistant to antibiotic-based treatments. The need for antimicrobial surfaces against bacteria and virus is a common factor to both crises. Most extended strategies to prevent bacterial associated infections rely on chemical based-approaches based on surface coatings or biocide encapsulated agents that release chemical agents. A critical limitation of these chemistry-based strategies is their limited effectiveness in time while grows the concerns about the long-term toxicity on human beings and environment pollution. An alternative strategy to prevent bacterial attachment consists in the introduction of physical modification to the surface. Pursuing this chemistry-independent strategy, we present a fabrication process of surface topographies [one-level (micro, nano) and hierarchical (micro+nano) structures] in polypropylene (PP) substrates and discuss how wettability, topography and patterns size influence on its antibacterial properties. Using nanoimprint lithography as patterning technique, we report as best results 82 and 86% reduction in the bacterial attachment of E. coli and S. aureus for hierarchically patterned samples compared to unpatterned reference surfaces. Furthermore, we benchmark the mechanical properties of the patterned PP surfaces against commercially available antimicrobial films and provide evidence for the patterned PP films to be suitable candidates for use as antibacterial functional surfaces in a hospital environment.This work is funded by the European Commission, under the project FLEXPOL (H2020-NMBPPILOT-2016-721062). The present study was carried out as part of a European project called “Antimicrobial FLEXible POLymers for its use in hospital environments” (FLEXPOL grant agreement No. 721062) funded by Horizon 2020 Framework Programme for Research and Innovation (2014-2020)

Label-free sensors based on perylenediimide-doped polystyrene distributed feedback lasers

Distributed feedback (DFB) laser sensors with active films consisting of a highly efficient and photostable perylenediimide dye (perylene orange, PDI-O) dispersed in polysytrene (PS), used as passive matrix, are reported. PDIdoped- PS DFB lasers show an excellent operational durability under ambient conditions, superior to those of previously reported DFBs used for sensing purposes. Their bulk refractive index sensing capabilities, under exposure to liquids of different refractive index, have been determined from changes in their emission wavelength. The role of the active film thickness on both, the laser and the sensing performance, has been explored. The use of a thick active film (850 nm) allows obtaining the lowest possible threshold and highest operational lifetime for this type of device although the sensor sensitivity is lower than that achievable with a thin film (160 nm). It is also shown that the inclusion of a high refractive index TiO2 layer on top of the sensor structure allows improving the sensor sensitivity by around two times.This work was supported by the Spanish Government (MINECO) and the European Community (FEDER) through grant no. MAT-2011–28167-C02. M.M-V. has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747)

Solution-processable, photo-stable, low-threshold, and broadly tunable thin film organic lasers based on novel high-performing laser dyes

Thin film organic lasers (TFOLs) represent a new generation of inexpensive, mechanically flexible devices with demonstrated applicability in numerous applications in the fields of spectroscopy, optical communications and sensing requiring an organic, efficient, stable, wavelength-tunable and solution-processable laser material. A distributed feedback (DFB) laser is a particularly attractive TFOL because it shows single mode emission, low pump energy, easy integration with other devices, mechanical flexibility and potentially low production cost. Here, amplified spontaneous emission (ASE) and DFB laser applications of novel high performing perylene dyes and p-phenylenevinylene (PV) oligomers, both dispersed in thermoplastic polymers, used as passive matrixes, are reported. Second-order DFB lasers based on these materials show single mode emission, wavelength tunability across the visible spectrum, operational lifetimes of >105 pump pulses, larger than previously reported PV oligomers or polymers, and thresholds close to pumping requirements with light-emitting diodes.This work was supported by the Spanish Government (MINECO) and the European Community (FEDER) through grant no. MAT-2011–28167-C02. M. Morales-Vidal has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747)

Organic distributed feedback laser for label-free biosensing of ErbB2 protein biomarker

The human epidermal growth factor receptor 2 (ErbB2) protein plays an important role in human malignancies. Its overexpression has been recognized as a feature of a malignant cancerous phenotype in breast cancer cell lines, and has become one of the most widely investigated clinical indicators of breast, ovarian, gastrointestinal and lung cancers. In this work a vertically emitting organic distributed feedback (DFB) laser has been used to detect the ErbB2 protein. This DFB laser consists of a polystyrene (PS) film containing a perylenediimide laser dye, deposited over a second-order one dimensional grating fabricated on fused silica by thermal-nanoimprint lithography and subsequent reactive ion etching processes. Specificity of the system to ErbB2 protein biomarker, achieved by functionalizing the PS with anti-ErbB2 monoclonal antibodies, is demonstrated. A concentration limit of detection for ErbB2 protein of 14 ng/mL has been obtained, and no cross-reactivity has been observed with bovine serum albumin (BSA) and tumor necrosis factor alpha (TNFα) proteins. These findings open the possibility of using this type of biosensors in clinical applications.This work was supported by the Spanish Government (MINECO) and the European Community (FEDER) through grant no. MAT-2011–28167-C02. This work was partially funded by the Basque Government within the framework of the Etortek Program (Grant No. IE13-360). M. Morales-Vidal has been partly supported by a MINECO FPI fellowship (no. BES-2009-020747)