In this work formation of conductive lines on the surface of AlN ceramic induced by laser radiation is presented. The transformation to conductive state is done be ablation of the ceramic surface using nanosecond Nd:YAG laser. The dependences of the processing conditions as applied laser fluence and the pulse overlapping on the resistance value are obtained for different surface modifications including straight lines, L, and + shapes. The formation of conductive structures is also studied for application of laser irradiation at the second (532 nm), third (355 nm) and fourth (266 nm) harmonics of the laser system. It is found that the resistance strongly depends on the processing conditions, as at appropriate choice it can be varied in a range of order of magnitude. Processing parameters windows are defined where the structure resistance has a minimal value. The performed analyses based on TEM, SEM, EDX, and Raman spectroscopy indicate that formation of aluminium layer, its oxidation and morphology define the processed areas conductivity. The role of oxidation is also confirmed by analyses of structures fabricated in vacuum, where significant reduction of the resistance is observed. It is found however, that a decrease of the ambient air pressure to 10 Torr is sufficient to obtain structures resistance of the same order as for processing in vacuum. Calculated data about the thickness of the conductive layer is also presented. The obtained results could be used in the design of microelectronic components, resistive elements, and novel optical materials.

In this work, we show that nanosecond laser processing of aluminium nitride (AlN) ceramic by a Nd:YAG laser operated at the fundamental wavelength (1064 nm) leads to the formation of a conductive layer decorated by a ripples structure. The characteristic orientation of these structures is perpendicular to the incident laser polarization. The period of the ripples is lower than the laser wavelength, namely, about 830 nm. Such structuring is observed after processing both in air and in vacuum. We discuss the mechanism of periodic structures formation based on the dependence of the surface morphology on the laser pulse number and fluence applied and the results of a simulation using the finite-difference time-domain approach. These results can form the basis of fabricating aluminium micro- and nanostructures with potential applications in electronics and photonics as systems for UV plasmonics.

In this paper, we describe the antibacterial action of Ag-doped Al 2 O 3 nanolayers deposited by RF reactive magnetron sputtering on stainless-steel surgical and microsurgical instruments. Synthesizing Ag/Al 2 O 3 protective coatings is necessary for suppressing the infections caused by pathogenic microorganisms following the application of surgical instruments. We further conducted microbiological studies on the action of the nanocomposite Ag/Al 2 O 3 layers against Gram-positive and Gram-negative bacteria ( Staphylococcus aureus and Escherichia coli ). The microbiological studies conducted proved the antibacterial effect of the nanocomposite Ag/Al 2 O 3 layers, the strongest effect against Escherichia coli and Staphylococcus aureus being observed after 48 hours of exposure. Also, the Ag/Al 2 O 3 nanolayers showed no cytotoxic effect. Our experimental findings suggest a very promising application of such antibacterial Ag/Al 2 O 3 nanolayers regarding the reduction of infections when stainless-steel surgical and microsurgical instruments are used.

Noble metal nanoparticle composed glasses attract significant attention due to the unique optical properties that they express in the near UV and visible spectral range. These are related to the high values of the extinction cross section and nonlinear optical characteristics. In this work we study the ability of laser irradiation to induce modification of the optical properties of borosilicate glasses that contain gold nanoparticles. The process is investigated by application of laser pulses of nanosecond Nd:YAG system on glasses that consist of nanoparticles with different size and shape. The results show that at certain conditions the glass optical properties can be modified as a change of the nanoparticles plasmon resonance wavelength is observed. The influence of the laser fluence and pulse number on this effect is studied. Two fluence regimes are defined: (i) at low fluences, close to the optical properties modification threshold the increase of the laser fluence results in a blue shift of the resonance wavelength; (ii) further increase of the laser fluences induces a red shift. Similar behavior is observed by changing the number of the applied pulses. Here after application of several thousand laser pulses additional, third regime of blue shift is realized. Theoretical models based on multiparticle Mie scattering theory and heat conduction equation are applied to explain the observed modifications. On their basis and performed analyses can be concluded that the induced optical properties variations are related to modification of the nanoparticles size and shape by melting, fragmentation and coalescence. The obtained results indicate an ability of nanoparticle size and shape modifications with a high spatial resolution in 3D and can be used for fabrication of integrated optical systems.

This work represents results on the response of noble metal-doped borosilicate glass to laser radiation with femto- and nanosecond pulse duration. The material under study is obtained by conventional melt quenching method as samples with noble metal concentration varied up to 10 wt% are fabricated. Optical and morphology changes of the glass samples induced by application of laser pulses with a wide range of parameters are studied. Below the permanent modification threshold, defects associated with formation of color centers in the material are observed and their properties as a function of the processing conditions are discussed. It is found that at certain conditions laser irradiation may induce direct formation of noble metal nanoparticles in the glass. When permanent morphology modifications are induced, different micro-and nanostructures are observed depending on the laser parameters. The morphology of the ablated area is studied as function of the laser fluence and number of the applied pulses. It is found that the presence of noble metal in the glass at concentrations up to 10 wt% (the maximal used) does not influence the ablation rate at both femto- and nanosecond ablation. The formation of defects and the composition of the material in the vicinity of the ablated zone are also discussed.

The process of laser radiation-induced formation and decomposition of Ag nanoparticles in glass is studied. Borosilicate glass samples are fabricated by melt quenching method. Silver nitrate is added in the fabrication stage in amount to form final glass samples with compositions of 1, 1.5, 5, and 10 wt% Ag. The fabricated samples are irradiated by laser pulses delivered by Nd:YAG nanosecond laser system at wavelength of 266 nm. It is found that at certain conditions laser radiation can induce coloration of the irradiated zone which is related to formation of silver nanoparticles. Detailed analyses are performed to characterize the formed nanoparticles. The application of a subsequent laser treatment of the glass samples with already formed nanoparticles can result in transparency recovery. The effect is demonstrated at wavelength of 355 nm of the Nd:YAG laser system. The observed formation and decomposition of nanoparticles are discussed on the basis of the calculated laser-induced heating dynamics and molecular dynamics simulation model for the silver atom motion. Diffusion growth and redox reactions are found to be responsible for the observed effects.

This paper describes the luminescence properties of small silver clusters formed by laser treatment of silverdoped borosilicate glass. Using irradiation by a Nd:YAG nanosecond laser system operating at the fourth harmonic wavelength (266 rim), areas are formed in the glass samples that emit bright luminescence peaking at about 600 nm when excited by UV light in the spectral range 300-390 nm. The influence is presented and discussed of the glass composition and the laser processing parameters on the emission characteristics. It is further shown that the luminescent properties are affected by the fluence of the excitation source, namely, a complete quenching of the emission is achieved above a certain value. The luminescence of the irradiated areas is explained by the formation of Ag clusters due to irradiation-induced reduction of Ag ions and increased atom mobility resulting from the local heating. The limited stability of the luminescent areas upon UV radiation can be related to heat-induced cluster decomposition and re-oxidation. The results obtained provide a new insight in the optical properties of noble-metal nanostructures and could form the basis of fabrication of complex optical systems and luminescent component used in the study of, e.g., biological systems.

In this work results on laser assisted formation of silver nanoparticles in glass are presented. The sample material used in the experiments is Ag doped borosilicate glass fabricated by conventional melt quenching method. The glass samples are irradiated by nanosecond laser pulses at wavelength of 266 nm with a wide range of fluences and number of applied pulses. It is found that the laser radiation can lead to specific yellow coloration of the irradiated areas. The performed analyses show formation of silver nanoparticles in these zones. The optical properties of the irradiated areas are found to depend on the laser processing parameters and the silver concentration. The mechanism of nanoparticle formation is also discussed. The presented method can be used for formation of nanoparticles inside transparent materials and can be used for fabrication of novel materials with application in photonics.

In this work the effects of laser radiation and annealing process on the change of the optical properties of gold doped borosilicate glass are presented. The glass is fabricated by conventional melt quenching method as samples with three different concentrations of gold are produced. The laser irradiation is performed by a Nd:YAG system that generates nanosecond pulses at wavelengths of 1064, 532, 355, and 266 nm. The optical properties of the glass samples are studied on the basis of their transmission spectra in the UV-near IR spectral range. The results indicate that irradiation at wavelength of 266 nm induces color changes assigned to formation of defects (color centers). Annealing of the samples results in formation of red colored zones which positions correspond to the irradiated ones. The optical properties and TEM observation indicate that this effect is related to formation of gold nanoparticles. The optical spectra of the areas irradiated by laser pulses and annealed are studied for different processing parameters pulse number, laser fluence, annealing temperature, annealing time, and the gold concentration in the glass. Processing parameters that ensure efficient tuning of the optical spectra are defined. The presented study can be a basis for a method for surface modification of glass samples that can lead to formation of nanoparticle composed layer with tunable optical properties for applications as novel optical elements. (C) 2017 Elsevier B.V. All rights reserved.

We present results on laser-induced color changes in gold- and silver-doped glass. The doped borosilicate glass was prepared by conventional melt quenching. The study was focused on the change of the optical properties after irradiation of the glass by femtosecond laser pulses. Under certain conditions, the laser radiation induces defects associated with formation of color centers in the material. We studied this process in a broad range of laser radiation wavelengths – from UV to IR, and observed changes in the color of the irradiated areas after annealing of the processed glass samples, the color being red for the gold-doped glass red and yellow for the silver-doped glass. The structural and morphological analyses performed indicated that this effect is related to formation of metal nanoparticles inside the material. The results obtained show that femtosecond laser processing of noble-metal-doped glasses can be used for fabrication of 3D-nanoparticles systems in transparent materials with application as novel optical components.

In this work, results on laser processing of thin metal films deposited on paper are presented. Au, Ag, Cu, and Ni films are deposited by classical pulsed laser deposition method on different paper types—standard printer, glossy, and silicone paper. The produced films are then processed by nanosecond pulses delivered by Nd:YAG laser system operating at the basic wavelength of 1064 nm. The laser processing parameters are varied and their influence on the film modification is presented. It is shown that at certain conditions, the laser treatment of the films leads to formation of a discrete nanostructure, composed of a monolayer of spherical nanoparticles. The structure and morphology of the fabricated samples are presented and discussed. Results on the use of these structures in Surface Enhanced Raman Spectroscopy are also presented. The demonstrated method is an alternative way for fabrication of metal nanostructures with application in low cost sensor device fabrication.

In this work, results on laser processing of thin zinc oxide films deposited on metal substrate are presented. ZnO films are obtained by classical nanosecond pulsed laser deposition method in oxygen atmosphere on tantalum substrate. The produced films are then processed by nanosecond laser pulses at wavelength of 355 nm. The laser processing parameters and the film thickness are varied and their influence on the fabricated structures is estimated. The film morphology after the laser treatment is found to depend strongly on the laser fluence as two regimes are defined. It is shown that at certain conditions (high fluence regime) the laser treatment of the film leads to formation of a discrete nanostructure, composed of spherical like nanoparticles with narrow size distribution. The dynamics of the melt film on the substrate and fast cooling are found to be the main mechanisms for fabrication of the observed structures. The demonstrated method is an alternative way for direct fabrication of ZnO nanostructures on metal which can be easy implemented in applications as resistive sensor devices, electroluminescent elements, solar cell technology. (C) 2015 Elsevier B.V. All rights reserved.