Microstructured surfaces on hard and brittle materials are widely used in a series of scientific and industrial applications, such as micro-electro-mechanical systems, nano-electro-mechanical ...systems, electronic devices, and medical products. However, the efficient precision machining of microstructured surfaces on hard and brittle materials faces great challenges. In this study, a new machining technology for high-efficiency precision fabrication of microstructured surface on hard and brittle materials was developed by a microstructured coarse-grained diamond grinding wheel. Initially, the laser microstructuring of the conditioned coarse-grained diamond grinding wheel was introduced. The influence of the laser-machined microstructure geometry on the form accuracy of the final, ground microstructured surface was theoretically analysed. Subsequently, the ductile regime grinding of the microstructured surface was examined for WC cermet and BK7 optical glass. The ground surfaces mainly under the ductile regime material removal were successfully achieved, especially in the case of WC ceramic. Finally, different linear and square microstructured surfaces with high form accuracy, sharp microstructure edge, and nanoscale surface roughness were efficiently fabricated on WC and BK7 optical glass by the method developed in the study.
This article presents a new simple method of creating light-absorbing carbon material for optical devices such as bolometers. A simple method of laser microstructuring of graphene oxide is used in ...order to create such material. The absorption values of more than 98% in the visible and more than 90% in the infrared range are achieved. Moreover thermal properties of the films, such as temperature dependence and the thermal response of the samples, are studied. The change in resistance with temperature is 13 Ohm K–1, temperature coefficient of resistance (TCR) is 0.3% K–1, and the sensitivity is 0.17 V W–1 at 300 K. Thermal conductivity is rather high at ∼104 W m–1 K–1 at 300 K. The designed bolometer operates at room temperature using incandescent lamp as a light source. This technique suggests a new inexpensive way to create a selective absorption coating and/or active layer for optical devices. Developed GO and rGO films have a large surface area and high conductivity. These properties make carbon coatings a perfect candidate for creating a new type of optoelectronic devices (gas sensors, detectors of biological objects, etc.).
The present article investigates the effect of graphite powder layers on the titanium surface layer during the treatment by the laser-induced plasma-assisted ablation method. Previous research mainly ...focuses on studying the effect of laser action on the quality of glass plate processing, rather than observing the changes in the substrate morphology caused by the treatment. Varying laser radiation parameters allowed obtaining the arrays of structures and determining the diagram of hardness values depending on the parameters of laser exposure. The method of laser treatment to increase the hardness of the surface layer under a graphite powder layer in contact with a dielectric transparent layer has been proposed and tested; the method has demonstrated a tenfold increase in the hardness of the surface layer. The results can be used in the improvement of cutting tools performance and applied in mechanical engineering or metalworking.
The thermo-plasmonic effect (heat deposition via absorption of laser light by metal nanoparticles) is applied to substantially enhance the effectiveness and controllability of the microstructure ...formation by laser-induced backside wet etching (LIBWE). Experiments were carried out with silicate glass plates using a pulsed 527 nm wavelength laser and an aqueous solution of AgNO3 as a precursor of the Ag nanoparticles. Mechanisms of such thermo-plasmonic LIBWE (TP-LIBWE) versions are considered. They involve: laser-induced photo-thermal reducing of silver (Ag) and self-assembling of Ag nanoparticles in water and the water/glass interface; fast laser-induced overheating of a water and glass surface through the thermo-plasmonic effect; formation of highly reactive supercritical water that causes glass etching and crater formation; generation of steam-gas bubbles in a liquid. It is significant that the emergence of the Marangoni convection results in bubble retention in the focal point at the interface and the accumulation of nanoparticles on the surface of the laser-induced crater, as this facilitates the movement of the bubbles with captured Ag particles from the fluid volume in the crater region, and accelerates the formation of the area of strong 'surface absorption' of laser energy. All these mechanisms provide a highly efficient and reproducible process for laser microstructure formation on the surface of glass using a novel TP-LIBWE technique.
•An Er:Yb doped KY(WO4)2/KY1−x−yGdxLuy(WO4)2 planar waveguide has been grown by LPE.•Ridge waveguides have been fabricated by beam-multiplexed fs-laser writing technique.•The proposed structures have ...been modeled using effective index method and BPM.•A passive characterization of the fabricated channel waveguides has been carried out.•Experimentally measured and numerically simulated results show a good agreement.
In the present work we propose a 2D-channel waveguide fabrication process based on the microstructuration of the cladding of a planar waveguide by femtosecond laser writing. The core of the waveguide is formed by a layer of KY1−x−yGdxLuy(WO4)2 epitaxially grown over a KY(WO4)2 substrate by means of Liquid Phase Epitaxy (LPE). A cladding of KY(WO4)2 is then grown by LPE over the core waveguide. To obtain lateral light confinement, the cladding is then micromachined using a multiplexed femtosecond laser writing beam, forming a ridge structure. Channel waveguides fabricated following this approach have been characterized in terms of their mode sizes and propagation losses at 0.98μm and 1.64μm, which are close to the wavelengths of interest in lasers/amplifiers based on the Er3+/Yb3+ system. Experimental data are compared with simulation analysis based on the Effective Index Method and the Beam Propagation Method, showing a good accordance between experimental and numerical results.
New results are presented for laser formation—in particular, the “drawing” of microstructures in polymer films using continuous-wave (CW) laser radiation λ = 405 nm with an intensity of 0.8–3.7 ...kW/cm2. The laser drawing was carried out in the polymer system poly-2,2′-p-oxydiphenylene-5,5′-bis-benzimidazole (OPBI), which consists of two phases: a solid polymer matrix with formic acid (HCOOH) dissolved in it. The formation of microstructures, including the stage of foaming, was carried out in three media: air, water and a supercritical carbon dioxide medium containing dissolved molecules of the silver precursor Ag(hfac)COD. The morphological features of foam-like track structures formed in the near-surface layer of the polymer films by laser “drawing” are considered. A model of processes is presented that explains the appearance of periodic structures. The key point of this model is that it considers the participation of the photoinduced mechanism of explosive boiling of formic acid molecules dissolved in the polymer matrix. Using Raman spectroscopy, spectra were obtained and interpreted, which relate to different stages in the formation of microstructures in OPBI films. The effects associated with the peculiarities of luminescent microstructures on the surfaces of glasses in close contact with polymer films during laser “painting” in the air have been studied.
In this paper, a mirrorless Yb 3+ -doped KY 1-x-y Gd x Lu y (WO 4 ) 2 waveguide laser with cw operation at 981.5 and 1001 nm, fabricated by liquid phase epitaxy and femtosecond laser ...microstructuring, is reported. A planar waveguide was fabricated by growing an Yb 3+ -doped KY 1-x-y Gd x Lu y (WO 4 ) 2 epitaxial layer by liquid phase epitaxy over a KY(WO 4 ) 2 substrate. This planar waveguide was then microstructured by means of a multiplexed beam femtosecond laser writing technique in order to define ridge waveguides. Mirrorless laser action is demonstrated in ridge waveguides with different fabrication parameters, obtaining maximum slope efficiency of 78% versus absorbed power, which confirms the feasibility of this technique for the development of integrated laser devices.
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t—The effect of ultraviolet (UV) laser radiation on the structure and adhesion properties of materials such as chromated bronze, stainless refractory austenitic chromium-nickel steels, and ...copper, has been experimentally studied. It has been shown that the surface microstructuring of elements of a diffusion-bonded joint improves its mechanical properties as to its tensile strength and tensile strain. Some results are presented for the laser perforation of a copper interlayer and the laser surface microstructuring of ceramic blanks which provide improvement in the mechanical properties of a Si
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Endoprostheses such as hip replacements are subject to wear. Lubrication of the joint interface plays a key role in the wear process, but the mechanisms of lubrication is challenging to understand. ...The main issue is the three-body abrasion which leads to a shorter life cycle. In order to improve the life cycle, the surfaces of the articulating components can be modified, for example by pulsed femtosecond-laser microstructuring. By microstructuring of the implant surface, the viscosity of the synovial fluid between the joint can be increased due to the non-Newtonian properties of the synovia. This leads to better lubrication and therefore lower particle abrasion. The objective of this study was to evaluate the impact of different microstructures on the viscosity of a joint fluid substitute. Various microstructures were investigated in a modified rheometer setup featuring a decreased gap size. As a test fluid, a synovial fluid substitute was used. The results show that an increase in the viscosity of the synovial fluid substitute can be achieved by microstructuring. An increase of viscosity of up to 20 % compared to the unstructured reference was observed with ring-structures with a diameter of 100 μm and a depth of 20 μm.
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