The generation of surface plasmon resonances (SPR) in laser-induced periodic surface structures (LIPSS) allows their application in the field of optical sensing, such as the detection of refractive index variations in gases and liquids. We have fabricated gold-coated LIPSS nanostructures on stainless steel substrates by using femtosecond laser nano-ablation. This technique is a low-cost and high-throughput fabrication method applicable to fast and large-scale manufacturing. The depth profile of the fabricated LIPSS shows a central dip at the top of each ripple that split the geometry. The actual topography is modeled and included in a computational electromagnetism package to obtain the expected optical response under the experimental conditions. The measured and simulated spectral reflectances are compared, and the differences are explained by the departure of the fabricated LIPSS from the ideal topography. The experiments and simulations showed excellent agreement for the main spectral characteristics, like the Fano-like lineshapes of the spectral reflectance. This fitting provides the values used to determine the refractometric performance of the fabricated device, that shows a sensitivity of 518 nm/RIU and a figure of merit of 32 RIU-1 for an aqueous analyte. Our experimental results show that the fabricated devices are competitive in terms of cost and simplicity when compared to existing devices with similar performance.

The use of ultrashort-pulsed (USP) lasers in Additive Manufacturing (AM) enables the processing of different materials and has the potential to reduce the sizes and shapes manufactured with this technology. This work confirms that USP lasers are a viable alternative for Laser Powder Bed Fusion (LPBF) when higher precision is required to manufacture certain critical parts. Promising results were obtained using tailored and own-produced stainless steel powder particles, manufacturing consistent square layers with a series of optimized processing parameters. The critical role of processing parameters is confirmed when using this type of lasers, as a slight deviation of any of them results in an absence of melting. For the first time, melting has been achieved at low pulse repetition (500 kHz) and using low average laser power values (0.5-1 W), by generating heat accumulation at reduced scanning speeds. This opens up the possibility of further reducing the minimum size of parts when using USP lasers for AM.

Laser-Induced Periodic Surface Structures (LIPSS) manufacturing is a convenient laser direct-writing technique for the fabrication of nanostructures with adaptable characteristics on the surface of virtually any material. In this paper, we study the influence of 1D laser wavefront curvature on nanoripples spatial regularity, by irradiating stainless steel with a line-focused ultrafast laser beam emitting 120 fs pulses at a wavelength of 800 nm and with 1 kHz repetition rate. We find high correlation between the spatial regularity of the fabricated nanostructures and the wavefront characteristics of the laser beam, with higher regularity being found with quasiplane-wave illumination. Our results provide insight regarding the control of LIPSS regularity, which is essential for industrial applications involving the LIPSS generation technique.

The control of the interaction between materials and biological tissues is a key factor to optimize the overall performance of implants and prostheses integrated into the body. With this objective in mind, biomimetic hierarchical one- and two-dimensional surface patterns textured at the micro and nano scales were fabricated on titanium alloys using femtosecond laser processing. The experimental results show that laser irradiation promotes surface oxidation together with a polarization-dependent nano-ripple formation. Human mesenchymal stem cells were subsequently cultured on different surface patterns aiming at determining their response to the underlying micro and nano structures. The ripple topography was demonstrated to induce a nonfouling behavior, which could be exploited in the fabrication of biomimetic hierarchical surface patterns to develop cell-trapping modules.

A diffractive optical element was fabricated by monolithically integrating two volume phase-gratings (VPGs) in the bulk of a single-piece transparent material. A computer model of the diffraction generated by the double volume phase-grating (DVPG) was made with a rigorous coupled wave analysis simulator. Simulations and experiments show that the diffractive behavior of a DVPG can be controlled by arranging the relative displacement and the distance between the VPGs according to Talbot self-imaging planes. In order to diffract the total incident light, the phase accumulation in the VPGs has to be pi/2, which was achieved by single-scan femtosecond laser processing of a nanocrystal doped glass as the substrate material. Ex situ microscope images of the cross-sections are presented for laser processed lines in the form of VPGs and DVPGs. The far-field diffraction of DVPGs formed by selectively located VPGs was characterized with a monochromatic 633 nm and a supercontinuum white light. Functional designs of high diffraction efficiency with potential applications in photonics were successfully fabricated in a one-step and free of chemicals process.

Volume-phase gratings (VPGs) were fabricated in CdSxSe1-x quantum-dot-doped borosilicate glass at a low repetition rate (800 nm, 140 fs, 1 kHz). The VPGs were designed based on rigorous coupled wave analysis simulations. Results indicate that the inscribed thickness (L) is the key parameter to maximize the diffraction efficiency at order 1. Microscope images of the cross sections and diffraction efficiency measurements were taken in order to characterize the modification of the material at different laser-inscription parameters. A maximum VPG diffraction efficiency of 67% (at order 1) was achieved. Also, a refractive index change of Delta n = 2.25.10(-3) is estimated from these VPG diffraction efficiency measurements. The measurements regarding polarization-insensitive diffraction efficiency showed that the birefringence produced in the substrate is negligible. (C) 2019 Optical Society of America

A combination of atomic layer deposition and photolithography is applied to fabricate interdigitated electrodes of aluminum-doped zinc oxide embedded in polyethylene terephthalate substrates. Various designs with different gap to widths ratios are realized and important characteristics of the electrodes, including thickness, surface roughness, and electrical properties with different ZnO:Al2O3 ratios are studied. Oxygen plasma is applied to etch the polyethylene terephthalate surface and to embed the electrodes, a methodology which is a breakthrough toward ultimately thin devices fabrication. Moreover, the influence of oxygen plasma on the electrical properties of aluminum-doped zinc oxide is analyzed in more detail. Electrochemical impedance spectroscopy studies of two different stimuli responsive ionogels are performed using the fabricated electrodes. The results show the suitability of the use of the fabricated electrodes to monitor changes in ion motion and morphology of stimuli responsive materials. These electrodes and the process of characterization of the ionogels presented could be implemented to monitor electrochemical changes in real applications such as protective coatings.

ZnO thin film sputtered on alumina substrate is processed by Direct Laser Interference Patterning (DLIP). The heat transfer equation has been simulated for interference patterns with a period of 730 nm and two different fluences (85 mJ/cm2 and 165 mJ/cm2). A thermal threshold of 900 K, where crystal modification occurs has been calculated, indicating a lateral and depth processing around 173 nm and 140 nm, respectively. The experimentally reproduced samples have been analyzed from the structural and composition point of view and compared to conventional thermal treatments at three different temperatures (600 ºC, 700 ºC and 800 ºC). Promising properties have been observed for the laser treated samples, such as low influence on the thin film/substrate interface, an improvement of the crystallographic structure, as well as a decrease of the oxygen content from O/Zn = 2.10 to 1.38 for the highest fluence, getting closer to the stoichiometry. The DLIP characteristics could be suitable for the replacement of annealing process in the case of substrates that cannot achieve high temperatures as most of flexible substrates.

We demonstrate a rapid, accurate, and convenient method for tailoring the optical properties of diamond surfaces by employing laser induced periodic surface structuring (LIPSSs). The characteristics of the fabricated photonic surfaces were adjusted by tuning the laser wavelength, number of impinging pulses, angle of incidence and polarization state. Using Finite Difference Time Domain (FDTD) modeling, the optical transmissivity and bandwidth was calculated for each fabricated LIPSSs morphology. The highest transmission of similar to 99.5% was obtained in the near-IR for LIPSSs structures with aspect ratios of the order of similar to 0.65. The present technique enabled us to identify the main laser parameters involved in the machining process, and to control it with a high degree of accuracy in terms of structure periodicity, morphology and aspect ratio. We also demonstrate and study the conditions for fabricating spatially coherent nanostructures over large areas maintaining a high degree of nanostructure repeatability and optical performance. While our experimental demonstrations have been mainly focused on diamond anti-reflection coatings and gratings, the technique can be easily extended to other materials and applications, such as integrated photonic devices, high power diamond optics, or the construction of photonic surfaces with tailored characteristics in general.

There is an increasing interest in nanoscience and nanotechnology due to the new physics and chemistry that are accessible on the nanoscale and because of the large potential for new products and devices that they provide. Therefore, the ability to fabricate structures on the nanoscale with high precision and in a wide variety of materials is a crucial issue for the development of the nanoscience and nanotechnology. Lithography and the other processes associated with it are the core of the nanotechnology revolution. One of the most promising techniques for the fabrication of structures on the nanoscale is Laser Interference Lithography (LIL). LIL, also known as holographic or interferometric lithography, is a well-established concept largely explored in lithography. However, a pulsed multi- beam LIL tool for nanoscale structuring of materials that can scale beyond laboratory prototypes into cost effective industrial processes is not yet defined. In this document, a versatile and automatic high-power multiple beam interference lithography system design capable of overcoming the limitations of manual setups is presented.

Nanotechnology is the study of the controlling of matter on an atomic and molecular scale and is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale. This new book gathers and presents data on nanotechnology including the growth of zinc oxide (ZnO) nanostructured films by means of excimer laser ablation; modeling defective carbon nanotubes by molecular mechanics; advances in surface functionalization of carbon nanotubes; the catalytic, optical, and thermodynamic properties of amorphous TiO2 nanoparticles.