Nanosecond Laser Pulses Research Articles

Realization of partially transmitted titanium/glass windows using a nanosecond pulsed laser

Titanium has been widely used in aerospace, ocean exploration, and other extreme fields because of its superior physical and chemical properties. In some specific fields, it is necessary to process titanium films to control the optical properties. In this study, we designed and fabricated four kinds of titanium-coated BK7 glass windows by using a weak 532 nm nanosecond pulsed laser and then analyzed their effective transmittance with a digital image processing approach. Finally, the actual effective transmittances of all processed samples were measured by utilizing a well-designed optical system. The results show that the total transmittance of the titanium-coated glass windows is from 5.70% to 48.72%. The processed four types of samples might be applied in different application scenes for the resistance of cosmic radiation. Such special windows we obtained in the study are thought to effectively shield cosmic rays and transmit some visible light at the same time. Our works may open up a new path for the realization of special windows used in some fields such as airline, outer space, scientific research stations at high altitude, etc.

A Study on the Manufacture of CNT Composites Bipolar Plate for the Fuel Cell Using a Nanosecond Pulsed Laser

The channels of the graphite-based bipolar plate for hydrogen fuel cells were mainly manufactured through milling due to low forming elongation and processability. However, during the milling process, the machining precision is low due to tool wear and vibration, and there is a risk of breakage. Non-traditional laser processing can solve the problems of tool wear and vibration through non-contact processing. In this study, the interaction characteristics of the nanosecond pulsed laser and CNT composites were observed, and channels and bipolar plates were manufactured. The effect of scanning speed and pulse duration was observed for interaction characteristics. Defects were observed due to high thermal effects at low scanning speed and high pulse duration. Channels were created depending on parallel pitch distance [] and Number of scans (NOS). The channel was evaluated for depth, top width, bottom width, channel angle, material removal rate, and surface roughness, and significant changes were observed depending on . The chemical composition, surface resistance, and contact angle of the laser-processed channel were measured. The laser processed channel was oxidized, and the surface resistance and contact angle increased. Finally, the manufacturability of the CNT composites bipolar plate using laser was examined.

Triple Rings Trepanning Technology for Holes Ablated Using Nanosecond Pulse Laser in Al2O3 Ceramics Substrate

Triple Rings Trepanning Technology for Holes Ablated Using Nanosecond Pulse Laser in Al2O3 Ceramics Substrate

Mapping nanoparticle formation and substrate heating effects: a fluence-resolved approach to pulsed laser-induced dewetting

This study investigates the fluence-dependent evolution of gold nanoparticles formed through single nanosecond pulsed laser dewetting of a gold thin film on a fused silica substrate. By employing a well-defined Airy-like laser spatial profile and reconstructing scanning electron microscope images across the irradiation spot into a panoramic view, we achieve a detailed continuous analysis of the nanoparticle formation process. Our morphological analysis, combined with finite element thermal simulations directly correlated with the applied fluence, identifies two distinct thresholds. The first threshold corresponds to the dewetting of the gold film at its melting point, resulting in large, sparse nanoparticles. The second threshold, where the substrate temperature reaches values near its melting point, leads to the formation of numerous small nanoparticles and a significant increase in coverage area. Notably, the formation of these small nanoparticles is attributed to substrate heating, which alters the interaction between the molten gold film and the substrate, increasing adhesion. Contact angle measurements of the nanoparticles confirm this change, revealing a shift in wettability, and highlighting the crucial role of substrate heating in modulating the interactions leading to nanoparticle formation. Our findings underscore the intricate interplay between laser fluence, material properties, and substrate interactions in pulsed laser dewetting, with the well-defined laser profile offering valuable insights into these dynamics.

Experimental study of flexible sensors based on ultraviolet nanosecond laser induced graphene

Current laser-induced graphene (LIG) methods encounter challenges such as subpar graphene quality and intricate manufacturing of electronic devices using graphene. In order to tackle these issues, this paper proposes a method of using an ultraviolet nanosecond pulse laser to stimulate the formation of graphene. Polyimide (PI) is subjected to laser irradiation in a single step to produce high-quality porous graphene. Subsequently, low-cost flexible pressure and strain sensors are manufactured using graphene. The Raman spectroscopy results demonstrate that the graphene generated has excellent quality (ID/IG = 0.14, I2D/IG = 0.37). Scanning electron microscopy shows that the LIG surface has a uniform porous morphology, with a patterning precision of 100 μm and a sheet resistance of 9.29 Ω/sq. The performance of the flexible pressure sensor was evaluated, demonstrating precise sensitivity (0.75 KPa−1 within 2.5 KPa range), a broad detection range (0–160 KPa), and a minimal detection limit of 20 Pa. The strain sensor exhibited a high level of sensitivity to strain (GF factor of 139), a broad linear range of strain (0–35 %), a low limit of detection (capable of detecting strains as low as 0.6 %), and outstanding durability (no signal distortion was observed even after subjecting it to over 2500 cycles of stretching). Flexible sensors can be worn as electronic skin on fingers, the neck, and the surface of robotic claws. The research results show that ultraviolet nanosecond pulsed lasers, using the LIG process, can produce graphene of higher known quality. The flexible pressure and strain sensors fabricated from this graphene exhibit outstanding performance.

Investigation on the impact of thermal softening effect induced by nanosecond pulsed laser-assisted cutting on the deformation mechanism of SiCp/Al composites

The machining of SiCp/Al composites containing high hardness SiC particles poses a significant challenge. The nanosecond pulsed laser-assisted cutting method has been selected to improve the machinability of SiCp/Al composites with a volume fraction of 45%. User-written subroutine is used to establish two dimensional and three dimensional cutting simulation models. The deformation mechanism of the Al matrix and SiC particles in SiCp/Al composites is investigated using cutting simulation, digital image correlation (DIC) experiments, and nanosecond pulsed laser-assisted cutting experiments. The effect of the various pulsed laser parameters on the surface quality of the workpiece is also investigated. The simulation and experimental results demonstrate that the damage of SiC particles and their arrangement hinder the plastic deformation of the Al matrix, and the nanosecond pulsed laser induces thermal softening effect and improve the plastic deformation of the Al matrix. Compared to the conventional cutting, the SiC particles exhibit a denser arrangement within the chip, and the plastic deformation of the Al matrix governs the chip deformation. The aim of this present study is to enhance the plastic deformation of the Al matrix, mitigate damage to SiC particles, improve the arrangement of SiC particles, and reduce the surface roughness of the workpiece in order to enhance the machinability of SiCp/Al composites.

Distinct nonlinear absorption behaviors in Cu1.8S nanocrystals influenced by geometry features

Spherical and lamellar [Formula: see text] nanocrystals with radial dimension of about 40[Formula: see text]nm were synthesized by the thermal injection method. Combining the crystal and morphological analysis with the photo physical property, the lamellar [Formula: see text] nanocrystals displayed the typical features of 2D metal sulfides which can be ultrasonically exfoliated into single or few layers of [Formula: see text] nanosheets due to the fact that the atomic layers were bonded by interlayer van der Waals forces. While in the spherical [Formula: see text] nanocrystals, no exfoliation or morphological change occurred after sonication. The nonlinear optical properties of spherical and lamellar [Formula: see text] nanocrystals after sonication were investigated by the [Formula: see text]-scanning technique using a 532-nm nanosecond laser pulse. The lamellar [Formula: see text] nanocrystals showed saturation absorption, reaching a normalized transmittance of 1.58 at [Formula: see text] with a [Formula: see text] value of [Formula: see text] and [Formula: see text] value of [Formula: see text]. While the spherical [Formula: see text] nanocrystals exhibited optical limiting effects, reaching the normalized transmittance of 0.38, with a [Formula: see text] value of 8[Formula: see text]cm/GW. Distinct nonlinear absorption behaviors in [Formula: see text] nanocrystals with the similar lateral size were observed in the spherical and lamellar [Formula: see text] nanocrystals, showing significant geometry feature-dependent nonlinear absorption behaviors.

WO3-Based Thin Films Grown by Pulsed Laser Deposition as Gas Sensors for NO2 Detection.

Thin films based on tungsten oxide (WO3) were grown by nanosecond pulsed laser deposition on alumina printed-circuit boards to fabricate electrochemical sensors for nitrogen dioxide (NO2) detection. Samples exposed to thermal annealing (400 °C for 3 h) were also produced to compare the main properties and the sensor performance. Before gas testing, the morphology and structural properties were investigated. Scanning electron microscopy and atomic force microscopy showed the formation of granular films with a more compact structure before the thermal treatment. Features of the main WO3 phases were identified for both as-deposited and annealed samples by Raman spectroscopy, whereas X-ray diffraction evidenced the amorphous nature of the as-deposited samples and the formation of crystalline phases after thermal annealing. The as-deposited samples showed a higher W/O ratio, as displayed by energy-dispersive X-ray spectroscopy. An Arrhenius plot revealed a lower activation energy (0.11 eV) for the as-deposited thin films, which are the most electrically conductive samples, presenting a better gas response (30% higher than the response of the annealed ones) in the investigated NO2 concentration range of 5-20 ppm at the moderate device operating temperature of 75 °C. This behavior is explained by a larger quantity of oxygen vacancies, which enhances the sensing mechanism.

Laser Cutting of Non-Woven Fabric Using UV Nanosecond Pulsed Laser.

The efficient cutting of non-woven fabric shows great significance to the development of the textile industry. In recent years, laser cutting technology has been widely applied in the clothing industry due to its high efficiency and cutting quality. In this work, a UV nanosecond pulsed laser with a wavelength of 355 nm and a max power of 6.5 W is used to cut non-woven fabric with a thickness of 0.15 mm. The variation of kerf width, surface morphology, and chemical contents are investigated under different laser processing parameters, and the optimal processing parameter is determined. The experimental results demonstrate that the degree of crystallization and chemical composition of the kerf on the non-woven fabric surface is significantly influenced by laser cutting parameters such as laser scanning speed (from 100 to 700 mm/s) and frequency (from 20 to 70 kHz). The scanning speed of 500 mm/s and frequency of 30 kHz are considered the best parameters for achieving abundant energy for the complete and efficient cutting of non-woven fabric. In addition, the level of carbonization and oxidation reaches a relatively low value, and the kerf width is 0.214 mm, which is considered a reasonable value under the optimal processing parameters, showing high cutting quality. Furthermore, the effect of different cutting treatments on surface morphology and chemical contents is also studied. The experimental results present that the non-woven fabric cut by laser possesses a flat kerf, showing a similar effect to that of scissor cutting. Moreover, due to the programmability of laser processing patterns, it is possible to create more intricate designs on non-woven fabric. This facilitates the application and promotion of laser-cut non-woven fabrics. These results can provide a certain reference for laser cutting in the textile industry and are expected to allow for the cutting of high-quality kerf with low carbonization and oxidation.

Heterogeneous ablation behavior of SiCf/SiC composite by nanosecond pulse laser

Heterogeneous ablation behavior of SiCf/SiC composite by nanosecond pulse laser

Processing characteristics of C/C composites with nanosecond pulse laser

This study investigates the effects of the nanosecond pulse laser parameters on the processing characteristics of carbon fiber-reinforced carbon matrix (C/C) composites through a series of laser cutting experiments. It compares the cutting width, depth, heat-affected zone (HAZ) width, processed surface micro-morphology, as well as the oxidation characteristics of the material under different processing parameters. The HAZ width is analyzed in relation to the variations in the oxygen content. The results indicate that both the cutting width and depth initially increase and then decrease with increasing repetition frequency. Moreover, increasing the laser power and pulse width gradually increases the cutting width, depth, and HAZ width, whereas a higher scanning speed tends to reduce the cutting width and depth. Since changes in the processing power, scanning speed, and pulse width affect the HAZ, the oxygen content exhibits a proportional relationship with the HAZ width. In addition, an increase in the repetition frequency can expand the HAZ while reducing the oxygen content. A careful increase in the repetition frequency aids in lowering the ablation threshold of the material, leading to more material removal. Nevertheless, a continuous increase in energy density can trigger a fiber pull-out phenomenon and cause degradation of the matrix.

Room-temperature ferromagnetic MnGa nanoparticles in dilute magnetic semiconductor (Ga, Mn)As thin film: preparation and characterization

The GaAs based diluted magnetic semiconductor, (Ga, Mn)As, with the unique advantage of manipulating the spin and charge was widely investigated in the scientific community and considered as a potential material for the spintronic devices. However, its Curie temperature (Tc), which is limited to around 200 K, hinders the research progress of diluted magnetic semiconductors for potential device applications. Herein, we propose an approach to prepare the MnGa nanoparticles embedded in (Ga, Mn)As matrix using the magnetron sputtering deposition of Mn on GaAs surface, followed by the nano-second pulsed laser annealing (PLA), which gives aTcabove 400 K. We demonstrate that the MnGa nanoparticles are only formed in (Ga, Mn) As thin film during the nano-second PLA under a critical range of energy density (0.4-0.5 J cm-2). The highest achieved coercivity, saturation magnetization and remanent magnetization are 760 Oe, 11.3 emu cm-3and 9.6 emu cm-3, respectively. This method for preparing the hybrid system of ferromagnetic metal/dilute magnetic semiconductor builds a platform for exploring the interesting spin transport phenomenon and is promising for the application of spintronic devices.

Optical absorption studies of pulsed-laser-engineered silver nanospheres and their enhanced catalytic performance in the degradation of toxic methylene blue dye

Pulsed laser ablation in liquid is an environment-friendly and one of the fastest physical routes to synthesize surfactant-free and stable metal/metal oxide nanoparticles with high purity and no harmful residues. In this study, we report the synthesis of silver nanospheres (AgNSs) using the nanosecond pulsed laser ablation in liquid (PLAL) technique resulting in the formation of a colloidal solution. Investigation of the optical properties using UV–Vis spectroscopy revealed the effects of laser wavelength, frequency, fluence, ablation time, and re-irradiation on the light absorption of the produced silver nanospheres. Physicochemical characterizations included FE-SEM, XRD, DLS, FTIR, and XPS techniques to evaluate the size, morphology, crystal structure, size distribution, zeta potential, and surface chemistry. FE-SEM studies revealed the formation of well-dispersed spherical Ag nanospheres with an average particle size of 209 nm without any agglomeration. DLS measurements showed high stability with a recorded zeta potential value of −38.27 (+/−1.81) mV and a wider size distribution. The XRD analysis indicated a face-centered cubic crystal structure with the formation of an oxide layer over the metallic silver core. The presence of silver and oxygen was confirmed through XPS studies with binding energies at 368.1 eV and 374.1 eV and oxide formation on the surface of Ag NSs. Finally, the catalytic activity of the Ag colloid was examined for the degradation of the toxic methylene blue dye. The results revealed an excellent catalytic response with 90 % of the dye degraded in just 15 min of reaction time. The kinetics of the degradation process were studied with a rate constant of 0.054/min−1 showcasing the effectiveness of the pulsed laser-synthesized silver colloidal nanomaterial as a sustainable approach for environmental remediation.

An improved laser photo-detachment diagnostic for negative ion density measurement

A photo-detachment Langmuir probe is a crucial tool because it gives a point measurement of negative ion density. The detection circuitry of a photo-detachment diagnostic with nanosecond laser pulses is critical for the accuracy of the results. Applying the electromagnetic theory to the design of the photo-detachment system has allowed it to stabilize its frequency response up to ~445 MHz, providing a significantly higher time resolution than in a common photo-detachment circuit setup. A systematic design rule is given in this paper to standardize the proper circuit. The new standard allows comparison between laboratories without concern for electronic parameter differences. The high-time resolution result shows three different peaks in the photo-detached electron current. This paper identified that the first peak is the most correlated to negative-ion density information, and the second and third peaks are related to background electrons interacting with build-up potential.

Ablation treatment of CFRP via nanosecond pulsed Ytterbium-doped fiber laser: Effects of process parameters on surface morphology and shear strength of adhesive bonded joints

Adhesive bonding is the joining technique that provides the maximum exploitation of Carbon Fiber Reinforced Polymers (CFRPs) for structural applications. However, it is necessary to attain a high-strength adhesive bond, achieved by removing surface contaminants, such as mold release agents, and simultaneously generating a surface structure suitable to increase the actual contact surface area. The purpose of the research work presented in this paper is to evaluate the effect of process parameters of a nanosecond pulsed laser pre-bonding surface treatment on the ablation of thermoset matrix CFRP substrates. In particular, the link between the volume of ablated material and the tensile shear strength (TSS) of adhesive bonded joints was evaluated by lap-shear tests, profilometer surveys, and Scanning Electron Microscope (SEM) analysis. ANOVA and regression models were used to highlight the influence of laser parameters, with power emerging as the most significant factor, and energy density proving pivotal for joint strength. Line spacing was also significant, while scanning direction had negligible impact. The key outcomes of the study demonstrated that controlled laser ablation plays a critical role in determining joint performance. A negative correlation was found between TSS and the thickness of ablated material, indicating that excessive ablation weakens the bond. Optimal joint strength was achieved with moderate fiber exposure while maintaining matrix integrity, emphasizing the need for precise control over laser parameters. Fracture surface analyses revealed distinct failure mechanisms, ranging from cohesive failure within the adhesive layer to interfacial failure at the fiber-matrix boundary, depending on the ablation conditions. The findings provide clear guidelines for optimizing laser surface treatments to enhance the structural performance of CFRP adhesive joints in practical applications.

Eco‐efficient recycling of carbon fibers from CFRP waste: A two‐step strategy by nanosecond pulsed laser

Eco‐efficient recycling of carbon fibers from <scp>CFRP</scp> waste: A two‐step strategy by nanosecond pulsed laser

Nanosecond pulsed laser coloring of the CrMnFeCoNi high entropy alloy

High-entropy alloys (HEAs) possess great potential for applications in the aerospace and military fields due to their excellent performance. Surface coloring can endow HEAs diverse functions. However, achieving a multi-color surface with minimal surface damage and cost remains a significant challenge. In this study, surface coloring of the CrMnFeCoNi HEA was attempted by nanosecond pulsed laser irradiation in air, and the multi-color surface was achieved. The evolution of surface color and morphology with laser parameters was analyzed. Then, five typical colors were selected, and the corresponding morphologies and chemical compositions were characterized by various techniques. The results showed that the change in oxide layer thickness as well as the formation of chromium-rich β-spinel and Cr (VI) compounds induced noticeable changes in surface color. Accordingly, complex surface patterns with various stable colors were prepared on the HEA surface, demonstrating the potential application of nanosecond pulsed laser coloring of HEAs.

Design of a compact beam transport system for laser-driven proton therapy

Abstract We put forward a new design of a compact beam transport system for intense laser-driven proton therapy, where instead of using conventional pulsed solenoids, our design relies on a helical coil irradiated by a nanosecond laser pulse to generate strong magnetic fields for focusing protons. A pair of dipole magnets and apertures are employed to further filter protons with large divergences and low energies. Our numerical studies combine particle-in-cell simulations for laser-plasma interaction to generate high-energy monoenergetic proton beams, finite element analysis for evaluating the magnetic field distribution inside the coil, and Monte-Carlo simulations for beam transport and energy deposition. Our results show that with this design, a spread-out Bragg peak in a range of several centimeters to a deep-seated tumor with a dose of approximately 16.5 cGy and fluctuation around 2% can be achieved. The instantaneous dose rate reaches up to 109 Gy/s, holding the potential for future FLASH radiotherapy research.

Optical and sign-flipping nonlinear optical properties of NiO/PMMA/PANI nanocomposite films

In this study, we introduce an efficient nanocomposite system to enhance optical properties of Nickel oxide (NiO) integrated with two polymers matrix. NiO nanoparticles is prepared using chemical co-precipitation method and its nanocomposite films (NCFs) were prepared with poly methyl methacrylate (PMMA) and polyaniline (PANI) using drop-casting method on glass substrate and was optimized by changing the concentration of NiO. The prepared NCFs were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), ultraviolet (UV)-visible absorption spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron (XPS) spectroscopy. The open-aperture z-scan method is employed for nonlinear optical investigations, utilizing a nanosecond pulsed laser with a wavelength of 532 nm for excitation. The findings indicate that the NCFs exhibit sign-flipping nonlinear behavior, indicating a transition from saturable absorption to reverse saturable absorption. This suggests that our NCFs exhibit optical limiting properties and potential for applications in photonic devices, such as optical switches and laser protection systems.

High-pulse-energy ultrafast 3 µm laser generation through OPG/DFG in PPMgLN

Abstract We report high-pulse-energy ultrafast 3 µm laser generation through optical parametric generation/difference frequency generation (OPG/DFG) in periodically poled magnesium-oxide-doped lithium niobate (PPMgLN). A commercial 1030 nm femtosecond laser is applied as the pump light and a homemade broadband nanosecond pulse laser around 1580 nm is used as the signal light in DFG. The broadband 1580 nm laser has a master oscillator power amplifier (MOPA) structure with a directly modulated superluminescent light-emitting diode (SLED) as the pulse seed and three stages of Er/Yb fiber amplifiers to lift its average power. A portion of the 1030 nm output pulse is converted to an electronic pulse via a pin detector, which is used as the trigger signal of the SLED driving circuit to ensure synchronization between the signal and the 1030 nm pump pulse. When injecting 2.12 W pump light into the PPMgLN, a broadband mid-infrared (MIR) output of 280 mW can be achieved directly through OPG with a center wavelength around 2.94 μm, a pulse width of 1.38 ps and a pulse repetition frequency of 500 kHz. The corresponding MIR pulse energy is 0.56 µJ. When injecting 2.62 W signal light simultaneously, a MIR output of 300 mW is achieved through the DFG process at the same pulse repetition frequency, corresponding to a pulse energy of 0.6 µJ. The conversion efficiency of the ultrafast pump laser to MIR reaches 14.1%. This high-pulse-energy 3 μm ultrafast laser has great prospects for applications in biological tissue ablation.