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14 pages, 5360 KiB

Open AccessArticle

Ultrafast Infrared Laser Crystallization of Amorphous Ge Films on Glass Substrates

by Yuzhu Cheng, Alexander V. Bulgakov, Nadezhda M. Bulgakova, Jiří Beránek, Martin Zukerstein, Ilya A. Milekhin, Alexander A. Popov and Vladimir A. Volodin

Micromachines 2023, 14(11), 2048; https://doi.org/10.3390/mi14112048 - 31 Oct 2023

Cited by 1 | Viewed by 925

Abstract

Amorphous germanium films on nonrefractory glass substrates were annealed by ultrashort near-infrared (1030 nm, 1.4 ps) and mid-infrared (1500 nm, 70 fs) laser pulses. Crystallization of germanium irradiated at a laser energy density (fluence) range from 25 to 400 mJ/cm² under single-shot [...] Read more.

Amorphous germanium films on nonrefractory glass substrates were annealed by ultrashort near-infrared (1030 nm, 1.4 ps) and mid-infrared (1500 nm, 70 fs) laser pulses. Crystallization of germanium irradiated at a laser energy density (fluence) range from 25 to 400 mJ/cm² under single-shot and multishot conditions was investigated using Raman spectroscopy. The dependence of the fraction of the crystalline phase on the fluence was obtained for picosecond and femtosecond laser annealing. The regimes of almost complete crystallization of germanium films over the entire thickness were obtained (from the analysis of Raman spectra with excitation of 785 nm laser). The possibility of scanning laser processing is shown, which can be used to create films of micro- and nanocrystalline germanium on flexible substrates. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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11 pages, 2476 KiB

Open AccessArticle

Comparative Study of Percussion Drilling in Glasses with a Femtosecond Laser in Single Pulse, MHz-Burst, and GHz-Burst Regimes and Optimization of the Hole Aspect Ratio

by Pierre Balage, Manon Lafargue, Théo Guilberteau, Guillaume Bonamis, Clemens Hönninger, John Lopez and Inka Manek-Hönninger

Micromachines 2023, 14(9), 1754; https://doi.org/10.3390/mi14091754 - 07 Sep 2023

Cited by 1 | Viewed by 1130

Abstract

In this contribution, we present a comparative study on top-down drilling in sodalime glass, with a femtosecond laser operating in single-pulse, MHz-burst and GHz-burst modes, respectively. We investigate the hole depth, drilling rate, and hole morphology for these three regimes while keeping the [...] Read more.

In this contribution, we present a comparative study on top-down drilling in sodalime glass, with a femtosecond laser operating in single-pulse, MHz-burst and GHz-burst modes, respectively. We investigate the hole depth, drilling rate, and hole morphology for these three regimes while keeping the same experimental conditions. We demonstrate that, for both burst regimes, the burst length has to be adapted for optimizing the hole depth. In the GHz-burst regime, the lower the ablation rate the longer the holes. The three drilling regimes lead to different hole morphologies, where the GHz-burst mode results in the best hole quality featuring glossy inner walls and an almost cylindrical morphology. Furthermore, we obtain crack-free holes, the deepest measuring 3.7 mm in length and 25 µm in entrance diameter corresponding to an aspect ratio of 150, which is the highest aspect ratio reported thus far with femtosecond GHz-burst drilling to the best of our knowledge. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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11 pages, 6181 KiB

Open AccessArticle

Increasing Heat Transfer from Metal Surfaces through Laser-Interference-Induced Microscopic Heat Sinks

by Frederic Schell, Richard Chukwudi Okafor, Tobias Steege, Sabri Alamri, Savan Ghevariya, Christoph Zwahr and Andrés F. Lasagni

Micromachines 2023, 14(9), 1730; https://doi.org/10.3390/mi14091730 - 02 Sep 2023

Cited by 1 | Viewed by 1109

Abstract

With the increasing processing power of micro-electronic components and increasing spatial limitations, ensuring sufficient heat dissipation has become a crucial task. This work presents a microscopic approach to increasing the surface area through periodic surface structures. Microstructures with a periodic distance of 8.5 [...] Read more.

With the increasing processing power of micro-electronic components and increasing spatial limitations, ensuring sufficient heat dissipation has become a crucial task. This work presents a microscopic approach to increasing the surface area through periodic surface structures. Microstructures with a periodic distance of 8.5 µm are fabricated via Direct Laser Interference Patterning (DLIP) on stainless steel plates with a nanosecond-pulsed infrared laser and are characterized by their developed interfacial area ratio. The optimal structuring parameters for increasing the surface area were investigated, reaching peak-to-valley depths up to 12.8 µm and increasing surface area by up to 394%. Heat dissipation in a natural convection environment was estimated by measuring the output voltage of a Peltier element mounted between a hot plate and a textured sample. The resulting increase in output voltage compared to an unstructured sample was correlated to the structure depth and developed interfacial area ratio, finding a maximum increase of 51.4%. Moreover, it was shown that the output voltage correlated well with the structure depth and surface area. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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18 pages, 17060 KiB

Open AccessArticle

Experimental Study on Carbon Fiber-Reinforced Polymer Groove Machining by High-Power Water-Jet-Guided Laser

by Shuo Meng, Yugang Zhao, Dandan Zhao, Chuang Zhao, Yu Tang, Zhihao Li, Hanlin Yu, Guangxin Liu, Chen Cao and Jianbing Meng

Micromachines 2023, 14(9), 1721; https://doi.org/10.3390/mi14091721 - 31 Aug 2023

Viewed by 1255

Abstract

Due to the excellent properties of carbon fiber-reinforced polymers (CFRPs), such as high strength and strong corrosion resistance, the traditional water-jet-guided laser (WJGL) technology has problems with fiber pull-out and has a small cutting depth when processing CFRPs. Therefore, in this study, we [...] Read more.

Due to the excellent properties of carbon fiber-reinforced polymers (CFRPs), such as high strength and strong corrosion resistance, the traditional water-jet-guided laser (WJGL) technology has problems with fiber pull-out and has a small cutting depth when processing CFRPs. Therefore, in this study, we used high-power water-jet-guided laser (HPWJGL) technology to perform groove processing experiments on CFRPs. The effects of four key process parameters, high laser power, pulse frequency, feed rate, and water-jet pressure, on the cutting depth were investigated by a single-factor experiment. The formation mechanism of groove cross-section morphology and the processing advantages of high-power water-jet-guided lasers were analyzed. On this basis, the mathematical prediction model of cutting depth was established by using the response surface method (RSM), and the optimal combination of process parameters was obtained. The mathematical prediction model was verified by experiments, and the error was only 1.84%, indicating that the model had a high reference value. This study provides a reference for the precision machining of HPWJGL technology. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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15 pages, 5344 KiB

Open AccessArticle

Bessel Beam Dielectrics Cutting with Femtosecond Laser in GHz-Burst Mode

by Pierre Balage, Théo Guilberteau, Manon Lafargue, Guillaume Bonamis, Clemens Hönninger, John Lopez and Inka Manek-Hönninger

Micromachines 2023, 14(9), 1650; https://doi.org/10.3390/mi14091650 - 22 Aug 2023

Cited by 1 | Viewed by 1472

Abstract

We report, for the first time to the best of our knowledge, Bessel beam dielectrics cutting with a femtosecond laser in GHz-burst mode. The non-diffractive beam shaping is based on the use of an axicon and allows for cutting glasses up to 1 [...] Read more.

We report, for the first time to the best of our knowledge, Bessel beam dielectrics cutting with a femtosecond laser in GHz-burst mode. The non-diffractive beam shaping is based on the use of an axicon and allows for cutting glasses up to 1 mm thickness with an excellent cutting quality. Moreover, we present a comparison of the cutting results with the state-of-the-art method, consisting of short MHz-bursts of femtosecond pulses. We further illustrate the influence of the laser beam parameters such as the burst energy and the pitch between consecutive Bessel beams on the machining quality of the cutting plane and provide process windows for both regimes. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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20 pages, 3819 KiB

Open AccessArticle

Optimising Surface Roughness and Density in Titanium Fabrication via Laser Powder Bed Fusion

by Hany Hassanin, Mahmoud Ahmed El-Sayed, Mahmoud Ahmadein, Naser A. Alsaleh, Sabbah Ataya, Mohamed M. Z. Ahmed and Khamis Essa

Micromachines 2023, 14(8), 1642; https://doi.org/10.3390/mi14081642 - 20 Aug 2023

Cited by 1 | Viewed by 1207

Abstract

The Ti6Al4V alloy has many advantages, such as being lightweight, formal, and resistant to corrosion. This makes it highly desirable for various applications, especially in the aerospace industry. Laser Powder Bed Fusion (LPBF) is a technique that allows for the production of detailed [...] Read more.

The Ti6Al4V alloy has many advantages, such as being lightweight, formal, and resistant to corrosion. This makes it highly desirable for various applications, especially in the aerospace industry. Laser Powder Bed Fusion (LPBF) is a technique that allows for the production of detailed and unique parts with great flexibility in design. However, there are challenges when it comes to achieving high-quality surfaces and porosity formation in the material, which limits the wider use of LPBF. To tackle these challenges, this study uses statistical techniques called Design of Experiments (DoE) and Analysis of Variance (ANOVA) to investigate and optimise the process parameters of LPBF for making Ti6Al4V components with improved density and surface finish. The parameters examined in this study are laser power, laser scan speed, and hatch space. The optimisation study results show that using specific laser settings, like a laser power of 175 W, a laser scan speed of 1914 mm/s, and a hatch space of 53 µm, produces Ti6Al4V parts with a high relative density of 99.54% and low top and side surface roughness of 2.6 µm and 4.3 µm, respectively. This promising outcome demonstrates the practicality of optimising Ti6Al4V and other metal materials for a wide range of applications, thereby overcoming existing limitations and further expanding the potential of LPBF while minimising inherent process issues. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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12 pages, 3742 KiB

Open AccessArticle

Very High-Aspect-Ratio Polymeric Micropillars Made by Two-Photon Polymerization

by Keynaz Kamranikia, Sébastien Dominici, Marc Keller, Niklas Kube, Karine Mougin and Arnaud Spangenberg

Micromachines 2023, 14(8), 1602; https://doi.org/10.3390/mi14081602 - 14 Aug 2023

Cited by 1 | Viewed by 1318

Abstract

Polymeric micropillars with a high-aspect-ratio (HAR) are of interest for a wide range of applications, including drug delivery and the micro-electro-mechanical field. While molding is the most common method for fabricating HAR microstructures, it is affected by challenges related to demolding the final [...] Read more.

Polymeric micropillars with a high-aspect-ratio (HAR) are of interest for a wide range of applications, including drug delivery and the micro-electro-mechanical field. While molding is the most common method for fabricating HAR microstructures, it is affected by challenges related to demolding the final structure. In this study, we present very HAR micropillars using two-photon polymerization (TPP), an established technique for creating complex 3D microstructures. Polymeric micropillars with HARs fabricated by TPP often shrink and collapse during the development process. This is due to the lack of mechanical stability of micropillars against capillary forces primarily acting during the fabrication process when the solvent evaporates. Here, we report different parameters that have been optimized to overcome the capillary force. These include surface modification of the substrate, fabrication parameters such as laser power, exposure time, the pitch distance between the pillars, and the length of the pillars. On account of adopting these techniques, we were able to fabricate micropillars with a very HAR up to 80. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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15 pages, 6230 KiB

Open AccessArticle

Research on Laser-Induced Damage Post-Restoration Morphology of Fused Silica and Optimization of Patterned CO₂ Laser Repair Strategy

by Xiao Shen, Ci Song, Feng Shi, Ye Tian, Guipeng Tie, Shuo Qiao, Xing Peng, Wanli Zhang and Zhanqiang Hou

Micromachines 2023, 14(7), 1359; https://doi.org/10.3390/mi14071359 - 30 Jun 2023

Viewed by 895

Abstract

Fused silica has become the preferred optical material in the field of inertial confinement fusion (ICF) due to its excellent performance; however, these costly optical elements are vulnerable, and their manufacture is time-consuming. Therefore, the restoration of laser-induced damage for these optical elements [...] Read more.

Fused silica has become the preferred optical material in the field of inertial confinement fusion (ICF) due to its excellent performance; however, these costly optical elements are vulnerable, and their manufacture is time-consuming. Therefore, the restoration of laser-induced damage for these optical elements is of great value. To restrain the post-restoration raised rim problem in the CO₂ laser repair process to improve the restoration quality, the separate influences of key parameters of laser power, irradiation duration, and laser beam diameter on post-restoration pit morphology are compared in combined simulation and experimental studies. An optimized, patterned CO2 laser strategy is proposed and verified; the results indicate that, with the strategy, the rim height decreases from 2.6 μm to 1.52 μm, and maximal photo thermal absorption is decreased from 784.2 PPM to 209.43 PPM. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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10 pages, 2982 KiB

Open AccessArticle

Advances in Femtosecond Laser GHz-Burst Drilling of Glasses: Influence of Burst Shape and Duration

by Pierre Balage, Guillaume Bonamis, Manon Lafargue, Théo Guilberteau, Martin Delaigue, Clemens Hönninger, Jie Qiao, John Lopez and Inka Manek-Hönninger

Micromachines 2023, 14(6), 1158; https://doi.org/10.3390/mi14061158 - 30 May 2023

Cited by 6 | Viewed by 1696

Abstract

The femtosecond GHz-burst mode laser processing has attracted much attention in the last few years. Very recently, the first percussion drilling results obtained in glasses using this new regime were reported. In this study, we present our latest results on top-down drilling in [...] Read more.

The femtosecond GHz-burst mode laser processing has attracted much attention in the last few years. Very recently, the first percussion drilling results obtained in glasses using this new regime were reported. In this study, we present our latest results on top-down drilling in glasses, focusing specifically on the influence of burst duration and shape on the hole drilling rate and the quality of the drilled holes, wherein holes of very high quality with a smooth and glossy inner surface can be obtained. We show that a decreasing energy repartition of the pulses within the burst can increase the drilling rate, but the holes saturate at lower depths and present lower quality than holes drilled with an increasing or flat energy distribution. Moreover, we give an insight into the phenomena that may occur during drilling as a function of the burst shape. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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10 pages, 6663 KiB

Open AccessArticle

Design and Realization of Polymeric Waveguide/Microring Structures for Telecommunication Domain

by Thuy Linh La, Binh Nguyen Bui, Thi Thanh Ngan Nguyen, Thi Lien Pham, Quoc Tien Tran, Quang Cong Tong, Aliaksandr Mikulich, Thanh Phuong Nguyen, Thi Thu Thuy Nguyen and Ngoc Diep Lai

Micromachines 2023, 14(5), 1068; https://doi.org/10.3390/mi14051068 - 18 May 2023

Cited by 1 | Viewed by 1338

Abstract

Polymer-based micro-optical components are very important for applications in optical communication. In this study, we theoretically investigated the coupling of polymeric waveguide and microring structures and experimentally demonstrated an efficient fabrication method to realize these structures on demand. First, the structures were designed [...] Read more.

Polymer-based micro-optical components are very important for applications in optical communication. In this study, we theoretically investigated the coupling of polymeric waveguide and microring structures and experimentally demonstrated an efficient fabrication method to realize these structures on demand. First, the structures were designed and simulated using the FDTD method. The optical mode and loss in the coupling structures were calculated, thereby giving the optimal distance for optical mode coupling between two rib waveguide structures or for optical mode coupling in a microring resonance structure. Simulations results then guided us in the fabrication of the desired ring resonance microstructures using a robust and flexible direct laser writing technique. The entire optical system was thus designed and manufactured on a flat base plate so that it could be easily integrated in optical circuits. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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13 pages, 3074 KiB

Open AccessArticle

Predictability of Astigmatism Correction by Arcuate Incisions with a Femtosecond Laser Using the Gaussian Approximation Calculation

by Isabel Llopis Sanmillan, Gabriele Thumann, Martina Kropp, Zeljka Cvejic and Bojan Pajic

Micromachines 2023, 14(5), 1009; https://doi.org/10.3390/mi14051009 - 07 May 2023

Viewed by 1588

Abstract

Planning astigmatic correction is a complex task. Biomechanical simulation models are useful for predicting the effects of the physical procedure on the cornea. Algorithms based on these models allow preoperative planning and simulate the outcome of patient-specific treatment. The objective of this study [...] Read more.

Planning astigmatic correction is a complex task. Biomechanical simulation models are useful for predicting the effects of the physical procedure on the cornea. Algorithms based on these models allow preoperative planning and simulate the outcome of patient-specific treatment. The objective of this study was to develop a customised optimisation algorithm and determine the predictability of astigmatism correction by femtosecond laser arcuate incisions. In this study, biomechanical models and Gaussian approximation curve calculations were used for surgical planning. Thirty-four eyes with mild astigmatism were included, and corneal topographies were evaluated before and after femtosecond laser-assisted cataract surgery with arcuate incisions. The follow-up time was up to 6 weeks. Retrospective data showed a significant reduction in postoperative astigmatism. A total of 79.4% showed a postoperative astigmatic value less than 1 D. Clinical refraction was significantly reduced from −1.39 ± 0.79 D preoperatively to −0.86 ± 0.67 D postoperatively (p 0.02). A positive reduction in topographic astigmatism was also observed (p < 0.00). The best-corrected visual acuity increased postoperatively (p < 0.001). We can conclude that customised simulations based on corneal biomechanics are a valuable tool for correcting mild astigmatism with corneal incisions in cataract surgery to improve postoperative visual outcomes. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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15 pages, 11206 KiB

Open AccessArticle

Investigation of Heat Accumulation in Femtosecond Laser Drilling of Carbon Fiber-Reinforced Polymer

by Yaoyao Li, Guangyu He, Hongliang Liu and Mingwei Wang

Micromachines 2023, 14(5), 913; https://doi.org/10.3390/mi14050913 - 23 Apr 2023

Cited by 1 | Viewed by 1727

Abstract

Carbon fiber-reinforced polymer (CFRP) has indispensable applications in the aerospace field because of its light weight, corrosion resistance, high specific modulus and high specific strength, but its anisotropy brings great difficulties to precision machining. Delamination and fuzzing, especially the heat-affected zone (HAZ), are [...] Read more.

Carbon fiber-reinforced polymer (CFRP) has indispensable applications in the aerospace field because of its light weight, corrosion resistance, high specific modulus and high specific strength, but its anisotropy brings great difficulties to precision machining. Delamination and fuzzing, especially the heat-affected zone (HAZ), are the difficulties that traditional processing methods cannot overcome. In this paper, single-pulse and multi-pulse cumulative ablation experiments and drilling of CFRP have been carried out using the characteristics of a femtosecond laser pulse, which can realize precision cold machining. The results show that the ablation threshold is 0.84 J/cm² and the pulse accumulation factor is 0.8855. On this basis, the effects of laser power, scanning speed and scanning mode on the heat-affected zone and drilling taper are further studied, and the underlying mechanism of drilling is analyzed. By optimizing the experimental parameters, we obtained the HAZ < 10 μm, a cylindrical hole with roundness > 0.95 and taper < 5°. The research results confirm that ultrafast laser processing is a feasible and promising method for CFRP precision machining. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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11 pages, 3577 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Pulse-on-Demand Operation for Precise High-Speed UV Laser Microstructuring

by Jernej Jan Kočica, Jaka Mur, Julien Didierjean, Arnaud Guillossou, Julien Saby, Jaka Petelin, Girolamo Mincuzzi and Rok Petkovšek

Micromachines 2023, 14(4), 843; https://doi.org/10.3390/mi14040843 - 13 Apr 2023

Viewed by 1670

Abstract

Laser microstructuring has been studied extensively in the last decades due to its versatile, contactless processing and outstanding precision and structure quality on a wide range of materials. A limitation of the approach has been identified in the utilization of high average laser [...] Read more.

Laser microstructuring has been studied extensively in the last decades due to its versatile, contactless processing and outstanding precision and structure quality on a wide range of materials. A limitation of the approach has been identified in the utilization of high average laser powers, with scanner movement fundamentally limited by laws of inertia. In this work, we apply a nanosecond UV laser working in an intrinsic pulse-on-demand mode, ensuring maximal utilization of the fastest commercially available galvanometric scanners at scanning speeds from 0 to 20 m/s. The effects of high-frequency pulse-on-demand operation were analyzed in terms of processing speeds, ablation efficiency, resulting surface quality, repeatability, and precision of the approach. Additionally, laser pulse duration was varied in single-digit nanosecond pulse durations and applied to high throughput microstructuring. We studied the effects of scanning speed on pulse-on-demand operation, single- and multipass laser percussion drilling performance, surface structuring of sensitive materials, and ablation efficiency for pulse durations in the range of 1–4 ns. We confirmed the pulse-on-demand operation suitability for microstructuring for a range of frequencies from below 1 kHz to 1.0 MHz with 5 ns timing precision and identified the scanners as the limiting factor even at full utilization. The ablation efficiency was improved with longer pulse durations, but structure quality degraded. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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24 pages, 7758 KiB

Open AccessArticle

Integrated Intelligent Method Based on Fuzzy Logic for Optimizing Laser Microfabrication Processing of GnPs-Improved Alumina Nanocomposites

by Khaled N. Alqahtani, Mustafa M. Nasr, Saqib Anwar, Ali M. Al-Samhan, Mohammed H. Alhaag and Husam Kaid

Micromachines 2023, 14(4), 750; https://doi.org/10.3390/mi14040750 - 29 Mar 2023

Cited by 1 | Viewed by 1417

Abstract

Studies on using multifunctional graphene nanostructures to enhance the microfabrication processing of monolithic alumina are still rare and too limited to meet the requirements of green manufacturing criteria. Therefore, this study aims to increase the ablation depth and material removal rate and minimize [...] Read more.

Studies on using multifunctional graphene nanostructures to enhance the microfabrication processing of monolithic alumina are still rare and too limited to meet the requirements of green manufacturing criteria. Therefore, this study aims to increase the ablation depth and material removal rate and minimize the roughness of the fabricated microchannel of alumina-based nanocomposites. To achieve this, high-density alumina nanocomposites with different graphene nanoplatelet (GnP) contents (0.5 wt.%, 1 wt.%, 1.5 wt.%, and 2.5 wt.%) were fabricated. Afterward, statistical analysis based on the full factorial design was performed to study the influence of the graphene reinforcement ratio, scanning speed, and frequency on material removal rate (MRR), surface roughness, and ablation depth during low-power laser micromachining. After that, an integrated intelligent multi-objective optimization approach based on the adaptive neuro-fuzzy inference system (ANIFS) and multi-objective particle swarm optimization approach was developed to monitor and find the optimal GnP ratio and microlaser parameters. The results reveal that the GnP reinforcement ratio significantly affects the laser micromachining performance of Al₂O₃ nanocomposites. This study also revealed that the developed ANFIS models could obtain an accurate estimation model for monitoring the surface roughness, MRR, and ablation depth with fewer errors than 52.07%, 100.15%, and 76% for surface roughness, MRR, and ablation depth, respectively, in comparison with the mathematical models. The integrated intelligent optimization approach indicated that a GnP reinforcement ratio of 2.16, scanning speed of 342 mm/s, and frequency of 20 kHz led to the fabrication of microchannels with high quality and accuracy of Al₂O₃ nanocomposites. In contrast, the unreinforced alumina could not be machined using the same optimized parameters with low-power laser technology. Henceforth, an integrated intelligence method is a powerful tool for monitoring and optimizing the micromachining processes of ceramic nanocomposites, as demonstrated by the obtained results. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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18 pages, 9354 KiB

Open AccessArticle

Modeling and Prediction of Water-Jet-Guided Laser Cutting Depth for Inconel 718 Material Using Response Surface Methodology

by Chuang Zhao, Yugang Zhao, Dandan Zhao, Qian Liu, Jianbing Meng, Chen Cao, Zhilong Zheng, Zhihao Li and Hanlin Yu

Micromachines 2023, 14(2), 234; https://doi.org/10.3390/mi14020234 - 17 Jan 2023

Cited by 2 | Viewed by 1915

Abstract

In this study, the water-jet-guided laser (WJGL) method was used to cut Inconel 718 alloy with high temperature resistance. The effect of critical parameters of the water-jet-guided laser machining method on the cutting depth was studied by a Taguchi orthogonal experiment. Furthermore, the [...] Read more.

In this study, the water-jet-guided laser (WJGL) method was used to cut Inconel 718 alloy with high temperature resistance. The effect of critical parameters of the water-jet-guided laser machining method on the cutting depth was studied by a Taguchi orthogonal experiment. Furthermore, the mathematical prediction model of cutting depth was established by the response surface method (RSM). The validation experiments showed that the mathematical model had a high predictive ability for cutting depth. The optimal cutting depth was obtained by model prediction, and the error was 5.5% compared with the experimental results. Compared with the traditional dry laser cutting, the water conducting laser method reduced the thermal damage and improved the cutting quality. This study provides a reference for the precision machining of Inconel 718 with a water-jet-guided laser. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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13 pages, 4813 KiB

Open AccessArticle

Fuzzy Control Modeling to Optimize the Hardness and Geometry of Laser Cladded Fe-Based MG Single Track on Stainless Steel Substrate Prepared at Different Surface Roughness

by Maha M. A. Lashin, Mahmoud Z. Ibrahim, Muhammad Ijaz Khan, Kamel Guedri, Kuldeep K. Saxena and Sayed M. Eldin

Micromachines 2022, 13(12), 2191; https://doi.org/10.3390/mi13122191 - 10 Dec 2022

Cited by 10 | Viewed by 1278

Abstract

Metallic glass (MG) is a promising coating material developed to enhance the surface hardness of metallic substrates, with laser cladding having become popular to develop such coatings. MGs properties are affected by the laser cladding variables (laser power, scanning speed, spot size). Meanwhile, [...] Read more.

Metallic glass (MG) is a promising coating material developed to enhance the surface hardness of metallic substrates, with laser cladding having become popular to develop such coatings. MGs properties are affected by the laser cladding variables (laser power, scanning speed, spot size). Meanwhile, the substrate surface roughness significantly affects the geometry and hardness of the laser-cladded MG. In this research, Fe-based MG was laser-cladded on substrates with different surface roughness. For this purpose, the surfaces of the substrate were prepared for cladding using two methods: sandpaper polishing (SP) and sandblasting (SB), with two levels of grit size used for each method (SP150, SP240, SB40, SB100). The experiment showed that substrate surface roughness affected the geometry and hardness of laser-cladded Fe-based MG. To predict and optimize the geometry and hardness of laser-cladded Fe-based MG single tracks at different substrate surface roughness, a fuzzy logic control system (FLCS) was developed. The FLCS results indicate that it is an efficient tool to select the proper preparation technique of the substrate surface for higher clad hardness and maximum geometry to minimize the number of cladding tracks for full surface cladding. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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8 pages, 1669 KiB

Open AccessArticle

Femtosecond Laser Induced Lattice Deformation in KTN Crystal

by Quanxin Yang, Bin Zhang, Yuanbo Li, Xuping Wang, Feng Chen, Pengfei Wu and Hongliang Liu

Micromachines 2022, 13(12), 2120; https://doi.org/10.3390/mi13122120 - 30 Nov 2022

Cited by 1 | Viewed by 1127

Abstract

In recent years, many novel optical phenomena have been discovered based on perovskite materials, but the practical applications are limited because of the difficulties of device fabrication. Here, we propose a method to directly induce localized lattice modification inside the potassium tantalate niobate [...] Read more.

In recent years, many novel optical phenomena have been discovered based on perovskite materials, but the practical applications are limited because of the difficulties of device fabrication. Here, we propose a method to directly induce localized lattice modification inside the potassium tantalate niobate crystal by using the femtosecond laser. This selective modification at the processed regions and the surrounding areas is characterized by two-dimensional Raman spectrum mapping. The spectrum variations corresponding to specific lattice vibration modes demonstrate the lattice structure deformation. In this way, the lattice expansion at the femtosecond laser irradiated regions and the lattice compression at the surrounding areas are revealed. Furthermore, surface morphology measurement confirms this lattice expansion and suggests the extension of lattice structure along the space diagonal direction. Moreover, the existence of an amorphization core is revealed. These modifications on the sample lattice can induce localized changes in physicochemical properties; therefore, this method can realize the fabrication of both linear diffraction and nonlinear frequency conversion devices by utilizing the novel optical responses of perovskite materials. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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15 pages, 7296 KiB

Open AccessArticle

Experimental Investigation on Ablation of 4H-SiC by Infrared Femtosecond Laser

by Lukang Wang, You Zhao, Yu Yang, Manman Zhang and Yulong Zhao

Micromachines 2022, 13(8), 1291; https://doi.org/10.3390/mi13081291 - 11 Aug 2022

Cited by 6 | Viewed by 2069

Abstract

Femtosecond laser ablation has become one of the important structural processing methods for the third-generation semiconductor material, silicon carbide (SiC), and it is gradually being employed in the manufacture of microelectromechanical systems and microelectronic devices. Experimental study has been performed on infrared single [...] Read more.

Femtosecond laser ablation has become one of the important structural processing methods for the third-generation semiconductor material, silicon carbide (SiC), and it is gradually being employed in the manufacture of microelectromechanical systems and microelectronic devices. Experimental study has been performed on infrared single and multiple pulses (1035 nm) femtosecond laser ablation of SiC at various processing parameters. Diameters of laser ablation spots on 4H-SiC were measured to estimate the absorption threshold for material modification and structural transformation, which were 2.35 J/cm² and 4.97 J/cm², respectively. In the multiple-pulse scribing ablation for microgrooves, the ablation threshold dropped to 0.70 J/cm² due to the accumulation effect when the effective pulse number reached 720. The calculated average of the thermally stimulated ablation depth of 4H-SiC is 22.4 nm, which gradually decreased with the raising of the effective pulse number. For obtaining square trenches with precise and controllable depths and a smooth bottom in 4H-SiC, the effects of processing parameters on the material removal rate and surface roughness are discussed. The ablation rate per pulse is almost constant, even if the effective pulse number varies. The reduction of laser spot overlapping ratio in x direction has a greater weakening effect on the material removal rate than that in y direction. The precise amount of material removal can still be controlled, while modulating the surface roughness of the ablated features by changing the hatch rotation angle. This research will help to achieve controllable, accurate, and high-quality machining results in SiC ablation, using infrared femtosecond laser. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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9 pages, 3832 KiB

Open AccessArticle

Manufacturing of Porous Glass by Femtosecond Laser Welding

by Hua Tan, Jiahui Pan, Xiaojia Zheng, Xiaoquan Fu, Yuxun Zhang, Yanxing Liu and Qiheng Huang

Micromachines 2022, 13(5), 765; https://doi.org/10.3390/mi13050765 - 12 May 2022

Cited by 2 | Viewed by 1999

Abstract

Based on femtosecond laser glass welding, four different porous structures of welding spots were formed by the manufacturing processes of spatiotemporal beam shaping and alternating high repetition rate transformation. Compared with an ordinary Gaussian beam, the welding spot fabricated by the flattened Gaussian [...] Read more.

Based on femtosecond laser glass welding, four different porous structures of welding spots were formed by the manufacturing processes of spatiotemporal beam shaping and alternating high repetition rate transformation. Compared with an ordinary Gaussian beam, the welding spot fabricated by the flattened Gaussian beam had smoother welding edges with little debris, and the bottom of the welding spot pore was flat. Instead of a fixed high repetition rate, periodically alternating high repetition rates were adopted, which induced multiple refractive indices in the welding spot pore. The welding spot pores manufactured by spatiotemporal beam shaping and alternating high repetition rate transformation have a special structure and excellent properties, which correspond to superior functions of porous glass. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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Review

Jump to: Research

15 pages, 1164 KiB

Open AccessReview

Laser-Based Manufacturing of Ceramics: A Review

by Pudhupalayam Muthukutti Gopal, Vijayananth Kavimani, Kapil Gupta and Dragan Marinkovic

Micromachines 2023, 14(8), 1564; https://doi.org/10.3390/mi14081564 - 06 Aug 2023

Cited by 2 | Viewed by 1830

Abstract

Ceramics are widely used in microelectronics, semiconductor manufacturing, medical devices, aerospace, and aviation, cutting tools, precision optics, MEMS and NEMS devices, insulating components, and ceramic molds. But the fabrication and machining of the ceramic-based materials by conventional processes are always difficult due to [...] Read more.

Ceramics are widely used in microelectronics, semiconductor manufacturing, medical devices, aerospace, and aviation, cutting tools, precision optics, MEMS and NEMS devices, insulating components, and ceramic molds. But the fabrication and machining of the ceramic-based materials by conventional processes are always difficult due to their higher hardness and mechanical properties. Therefore, advanced manufacturing techniques are being preferred for these advanced materials, and out of that, laser-based processes are widely used. The benefits of laser fabrication and machining of ceramics include high precision, reduced thermal damage, non-contact processing, and the ability to work with complex geometries. Laser technology continues to advance, enabling even more intricate and diverse applications for ceramics in a wide range of industries. This paper explains various laser based ceramic processing techniques, such as selective laser sintering and melting, and laser machining techniques, such as laser drilling, etc. Identifying and optimizing the process parameters that influence the output quality of laser processed parts is the key technique to improving the quality, which is also focused on in this paper. It aims to facilitate the researchers by providing knowledge on laser-based manufacturing of ceramics and their composites to establish the field further. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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