ABSTRACT Metasurfaces, as artificially engineered two‐dimensional platforms for precise electromagnetic wave manipulation, have revealed revolutionary potential across imaging, sensing, and communication domains. Nevertheless, their practical adoption remains hindered by persistent challenges in achieving high‑precision and high‑efficiency fabrication of subwavelength architectures. Laser‑based processing emerges as a pivotal strategy to address these constraints, leveraging its unparalleled advantages including maskless operation, genuine three‑dimensional processing freedom, and broad material compatibility. This review systematically elucidates recent progress in laser‑fabricated metasurfaces. It begins with a delineation of the fundamental physical mechanisms governing femtosecond laser interactions with critical material systems, such as metals, dielectrics, and semiconductors. Subsequently, a comprehensive overview is presented of three principal laser processing modalities—subtractive, modificative, and additive approaches—analyzing their operational principles, performance benchmarks, and application landscapes. Special emphasis is placed on key enabling technologies, including beam shaping, aberration correction, and thermal management at hetero‑interfaces, which substantially augment fabrication capabilities and functional diversity. Finally, a prospective analysis is provided of outstanding challenges and future research trajectories toward industrialization, highlighting issues such as large‑area uniformity, multi‑material integration, and intelligent manufacturing paradigms.

Abstract This study addresses key challenges in micro-hole machining of Inconel 718 by proposing a composite process that combines nanosecond laser drilling with a self-generated NaCl abrasive jet. Conventional laser drilling often suffers from limited precision and severe thermal damage. In the proposed method, a heated NaCl solution is cooled to precipitate micron-scale NaCl crystals, which act as abrasives during laser processing. The synergistic action of particle impact/micro-grinding and laser-induced melting enhances material removal, suppresses the heat-affected zone, and improves hole-wall integrity. The method enables high-quality micro-hole fabrication with improved dimensional consistency, demonstrating potential for manufacturing film-cooling holes in aeroengine turbine blades.

Abstract A backscattered abrasive flow–assisted laser machining method is proposed to improve microhole quality in nickel-based superalloys. Using B 4 C abrasives and Inconel 718, the study investigates the effects of liquid layer position and jet velocity on microhole morphology under fixed laser parameters. The results show that an appropriately matched liquid layer position and moderate jet velocity effectively enhance molten material removal, suppress plasma shielding and molten re-solidification, and significantly improve hole wall quality and taper.

To achieve high-quality microhole processing at elevated laser powers, this work proposes a synergistic strategy-backside flowing chemical-assisted laser pulse-delayed scanning drilling [time-delayed (TD)-backside chemical-assisted laser drilling (BCALD)]. Unlike conventional immersion-based liquid-assisted laser drilling, which often suffers from significant plasma shielding and uncontrollable chemical etching, TD-BCALD significantly enhances energy utilization efficiency by precisely modulating the spatiotemporal coupling between laser pulses and chemical reactions. By coordinating a continuous flow of environmentally benign chemical fluid with an intermittently activated high-power laser in a pulse-delay regime, this approach enables highly controllable synergistic interactions within the laser-induced high-temperature zone. We first outline the individual mechanisms and key parameters of BCALD and laser pulse-delayed scanning drilling and then highlight how pulse-delay timing critically modulates their synergy. Detailed scanning electron microscopy and x-ray energy spectrometry analyses further elucidate the underlying mechanism of heat accumulation decoupling. Under an optimal 100 ms pulse delay, TD-BCALD achieves a taper angle of 0.987 degrees, roundness of 98.9%, and surface roughness of 1.502 mu m. These results, combined with the reduced chemical consumption and improved process stability, demonstrate the superior engineering potential and environmental benefits of TD-BCALD for advanced high-power laser microfabrication.

SiCf/SiC composites present significant machining challenges due to their inherent characteristics. Although laser processing is considered a promising technique for machining SiCf/SiC composites, it faces limitations such as surface oxidation during laser ablation. To address these issues, this study investigates a hybrid approach combining underwater nanosecond laser ablation with post-processing using chemical solutions. A comparative analysis of ablation morphologies and elemental compositions was conducted between processing in ambient air and underwater environments. The results indicate that air channels formed during laser ablation, oxygen ions in water, and hydroxyl radicals (center dot OH) generated from collapsing cavitation bubbles contribute significantly to oxidation. The growth of oxides underwater follows a mechanism based on bubble-induced directional solidification and the aggregation of multi-scale particles. Notably, the oxides formed in the underwater environment are more readily removable, and when the power exceeds 40 W, concentric circular scanning during processing proves more advantageous for achieving desirable micro-hole morphology.

Femtosecond laser single-focus scanning has the problem of low efficiency when manufacturing large-area structures. This paper proposes a multi-focus parallel processing method based on the weighted Gerchberg-Saxton (GS) algorithm. A multi-focus hologram was designed and loaded onto a spatial light modulator to achieve uniform energy distribution. The effects of repetition frequency, pro-cessing times and scanning speed on the morphology of microchannels were systematically studied, and the uniformity was all above 90%. Using the opti-mized process parameters, a grating structure with a cross-sectional width of approximately 29.315 μm was fabricated inside the glass by the three-focal parallel process. Compared with single-focus scanning, this method triples the efficiency while maintaining high quality, providing a promising path for the manufacturing of scalable photonic devices.

To break through the limitations of traditional rectangular microchannel processing methods for microfluidic devices, this paper proposes a processing technique based on a holographic combined femtosecond laser beam. The phase and topology of the hologram are adjusted by SLM to flexibly control the spot width and energy distribution of a generated Bessel beam, thus realizing high-precision and multi-size processing. To achieve high-precision microchannel sidewalls and bottom surfaces, the positive first-order Bessel beam is shifted at an appropriate position after the zero-order light by using a blazed grating to obtain the suggested holographic combined beam required for processing. At a laser power of 0.98 W, compared with using only the Gaussian beam (bottom roughness Ra of 0.361 μm, MRR of 882.219 μm³/s) and the Bessel beam (Ra of 0.377 μm, MRR of 3490.590 μm³/s), processing with the combined beam reduces Ra to 0.128 μm, a reduction by factors of 2.8 and 2.9, respectively. Meanwhile, the MRR increases to 6786.362 μm³/s, representing improvements by factors of 7.7 and 1.9, respectively. Under this power, when the phase value s increases by 4 pixels, the microchannel width increases by 3.2 μm, and when the topological charge n increases by 4 pixels, the microchannel depth decreases by 0.7 μm. This novel method, which enables smooth surfaces without the need for post-processing, offers a new option for the high-quality, efficient, and flexible fabrication of curable resin microfluidic devices.

In this paper, the experiment of IN718 superalloy was carried out with the aid of liquid, and the influence of liquid aid on key indexes such as hole taper and diameter of inlet and outlet was systematically analyzed. At the same time, the chemical element composition of the hole wall was detected, and the thickness of oxide layer formed in different environments during machining was studied. Finally, the processing mechanism of IN718 superalloy nanosecond laser drilling under liquid-assisted conditions is discussed. The results show that both water-assisted and liquid-assisted can improve the quality of micropores in different degrees compared with the condition without auxiliary field in air, especially the effect of liquid-assisted is the most significant. Under this condition, the hole taper is reduced by 67%. In addition, with the help of liquid, the content of oxygen element in the pore wall of micropores is greatly reduced, and the element composition is closer to the base material. This study provides important theoretical support and technical optimization direction for nanosecond laser drilling technology.

To address issues such as thick recast layers, high pore wall roughness, and dif-ficult-to-control geometric accuracy during micro-hole machining of nick-el-based high-temperature alloy 718, a laser-electrochemical hybrid pro-cessing method assisted by abrasive jet is proposed. By establishing a synergistic “electrolyte abrasive jet-nanosecond laser” processing system, combined with multiphysics coupling simulation and experimentation, this study sys-tem-atically investigates the influence mechanisms of parameters such as jet veloci-ty, jet angle, abrasive particle size, and voltage on microhole roundness, taper, wall roughness, surface morphology, and recast layer formation. Results indi-cate that moderate jet and electrical parameters significantly enhance ori-fice morphology and wall quality while effectively suppressing microcracks and re-cast layers. Orthogonal experiments optimized the following optimal process parameters: jet velocity 8 m/s, jet angle 60°, abrasive particle size 15 μm, volt-age 15 V, and current 3 A. Under these parameters, the micro-hole round-ness, surface morphology, and taper achieved optimal values, while hole wall rough-ness was significantly reduced and surface quality markedly improved.

This study investigates the optimization of process parameters for water-jet-assisted nanosecond laser drilling of Inconel 718, with a focus on improving microhole quality through pulse delay strategies and defocus control. Expe-ri-ments were conducted using concentric circular scanning under both un-derwa-ter and in-air conditions, with emphasis on the effects of delay meth-ods—specifically face-delay and line-delay—on geometric accuracy and mor-phologi-cal integrity. Results indicate that the line-delay approach significantly reduces entrance diameter, taper, microcracks, and oxidation compared to non-delayed and face-delayed conditions. The ablation threshold increased from 12.58 J/cm² in air to 22.12 J/cm² underwater due to energy attenuation effects. Optimal machining quality was achieved with a defocus distance of –0.5 mm, corre-sponding to focal positioning near the workpiece center. The study de-mon-strates that waterjet-assisted laser drilling with adaptive pulse delay effec-tively enhances machining precision and surface quality, showing great poten-tial for applications in high-temperature component manufacturing.

Laser processing has emerged as a pivotal technique for micro-hole fabrication owing to its exceptional efficiency and absence of tool wear. Nevertheless, certain imperfections persist in laser drilling. Consequently, this study presents a comprehensive analysis of the impact of laser processing parameters, methods, and physical field-assisted techniques on the quality and efficiency of laser drilling based on the characteristics desired for micro-holes. The findings reveal that selecting an appropriate laser wavelength and pulse width, coupled with meticulous adjustments to laser power, repetition frequency, and defocusing amount can enhance either processing efficiency or micro-holes quality; however, optimizing both aspects simultaneously remains challenging. By refining scanning strategies and implementing pulsed joint secondary repair approaches, heat accumulation is minimized while micro-holes quality is optimized; nevertheless, ensuring high processing efficiency poses difficulties. Ultrasonic assisted laser drilling enhances processing efficiency by facilitating the expulsion of molten materials, while magnetic field-assisted laser drilling improves processing efficiency by mitigating the attenuation of the laser caused by plasma clouds. Both techniques contribute to enhancing the quality of hole walls through their stirring effect. Water-based ultrasonic/magnetic field-assisted laser perforation combines heat dissipation and secondary flushing effects with ultrasonic/magnetic field assistance, resulting in superior micro-hole formation. Magnetic field-ultrasonic assisted laser perforation synergistically combines both effects. Furthermore, this study distinguishes between the promoting and inhibiting effects of rotating and static magnetic fields on molten metal flow, elucidating the impact of ultrasound and magnetic fields on molten metal from a melt dynamics perspective. Finally, we summarize the influence of each optimization method on micro-hole quality characteristics and processing efficiency while providing insights into future development trends.

Surface finish is a crucial quality characteristic of medical device components. However, existing surface polishing technologies have some shortcomings, such as difficulty in controlling the polishing effect, poor precision, and inability to manage components with complex shapes. In this study, a laser-chemical composite polishing system was designed and built for the precision polishing of medical-grade TC4 titanium alloy. The material removal mechanism of laser-chemical composite machining was analyzed. The evolution process of the material surface morphology and surface roughness changes at different polishing stages was investigated by conducting laser chemical composite polishing experiments on medical TC4 titanium alloys; thus, clarifying the mechanism of laser chemical composite polishing. The results show that material removal by laser-chemical composite polishing is based on the combined influence of laser thermal-mechanical effects and laser-induced chemical corrosion. Moreover, these two factors have a synergistic effect under certain conditions, which can mutually promote and enhance material removal efficiency and processing quality. Within an appropriate process window, chemical dissolution can completely remove the residues and remelts generated by laser ablation. Laser irradiation causes temperature differences between the peak and valley regions of the material surface, leading to different chemical dissolution rates. By exploiting the difference in the dissolution rates between the peaks and valleys on the surface of the workpiece, improvements in the surface roughness of the laser-irradiated region were achieved. Moreover, the chemical polishing mechanism is based on the atomic-scale dissolution of materials, which results in higher polishing precision compared with laser thermo-mechanical etching. The ratio of the laser etching material removal to the chemical dissolution material removal determines the ultimate roughness limit of the titanium alloy surface. A higher proportion of chemical dissolution resulted in better surface smoothness but a lower polishing efficiency. Therefore, during the final polishing stage, reducing the energy of laser irradiation on the workpiece surface can decrease the laser etching ratio and improve the final polishing effect. Additionally, the uneven distribution of the alloying elements on the surface of the TC4 titanium alloy affected the final surface smoothness. This is because Al and Fe in TC4 titanium alloys exhibit better chemical activity in acidic environments than V and Ti. During the chemical corrosion process, micro-galvanic cell phenomena occur, leading to preferential dissolution of the anode. Therefore, based on the chemical polishing mechanism, it can be understood that the ultimate polishing limit is influenced by the purity and microstructure of the material. The purer the material composition and smaller the microstructure, the better the final polishing effect. The selective removal of laser-chemical composite polishing is based on laser etching and thermochemical dissolution induced by laser activation. During laser-chemical composite polishing, laser irradiation acts as a local and selective heat source, inducing appropriate thermal shock and activating a non-uniform chemical reaction between the chemical solution and metal surface, resulting in temperature-induced chemical corrosion. In the laser irradiation area, the passivation film on the metal surface was stripped and dissolved under the dual action of physics and chemistry, whereas other parts of the workpiece material were protected by the passivation film, and almost no corrosion occurred. Under the continuous action of laser etching and chemical dissolution, the etching rates in the laser-irradiated and non-irradiated areas were significantly different, thereby achieving selective etching of the metallic material. The presence of bubbles during processing significantly affects the laser-chemical composite polishing. The causes of bubble generation were analyzed, and several methods were proposed to overcome bubble disturbances. It was demonstrated through experiments that, after taking appropriate measures, the bubble disturbance during the polishing process can be effectively reduced. Finally, the selective precision polishing of the medical TC4 titanium alloy was achieved using suitable process parameters. The surface roughness of laser irradiation area Ra decreased from 5.230 mu m to 0.225 mu m, and Sa decreased from 8.630 mu m to 0.571 mu m, which is a decrease of 95.7% and 93.4%, respectively. These research findings provide a reference for the precision polishing of titanium alloys or other self-passivating metal

The method of backwater-assisted picosecond laser secondary hole repairing(LSHR) is proposed to achieve high quality processing of the micro-holes. LSHR helps to reduce the difference in polarized light reflectivity and improve the roundness of the micro-hole outlet. The improvement of the discharge capacity of plasma and steam plays a key role in the improvement of the material removal rate and the improvement of periodic stripes. The mechanism of the two scanning modes was briefly discussed, and the processing effect of LSHR under different combinations of scanning modes was determined, so as to obtain the best combination of high-quality micro holes. Under the best combination, the micro-hole taper is 1.476 degrees, and the micro-hole outlet roundness is 0.924 %. The backwater-assisted method can further increase the material removal rate, reduce the micro-hole taper, and improve the quality of the hole wall. Compared with the air, the micro-hole taper is reduced by 0.636 degrees. However, the micro-hole outlet is more elliptical due to the refractive index of water. The experimental results provide a new reference for optimizing the picosecond laser drilling process.

随着高端精密装备的飞速发展,人们对高质量微孔的需求越来越迫切.激光加工凭借其加工精度高、效率高、无污染、应用材料范围广等优点成为微孔加工制造的首选方法.文章首先对激光加工微孔的质量特征(如深径比、锥度、圆度等)进行了介绍;其次总结归纳了激光加工方式(复制法和轮廓迂回法)、辅助方式(真空、气体、水等因素)和超声-激光复合加工对微孔质量的影响;最后对激光加工微孔存在的问题进行总结,并对未来发展方向进行了展望.

为解决自建激光并行加工实验平台因设备安装位置隐蔽、难以加装辅助装置等而造成实验操作不便、设备运行状态监测困难和交互性差的问题,以实验平台中单个光学位移台为例,利用Unity引擎设计了一种基于数字孪生技术的交互控制系统.该交互控制系统采用MQTT(message queuing telemetry transport,消息队列遥测传输)通信协议,利用服务器中转数据的方式完成跨软件间的信息交互.光学位移台的Kinesis控制软件和Unity引擎中的虚拟控制面板作为MQTT通信中的客户端,共同承担订阅者和发布者的角色.光学位移台的数字孪生模型根据数据信息对物理实体的运动状态进行实时映射,用户通过Kinesis控制软件或虚拟控制面板完成对物理实体和数字孪生模型的同步交互控制.采取引用.dll文件对Kinesis控制软件进行二次开发,调用Kinesis控制软件运动控制类的方法完成对光学位移台的运动控制,并将运动数据变量设置为高精度的float型和decimal型,确保数据精度不丢失.选取10组实际加工数据对交互控制系统运行的延时性、同步性进行测试.结果显示,Kinesis控制软件端数据发布耗时和Unity引擎端数据订阅耗时分别控制在20 ms和10 ms内.所设计的系统能够较好地保证数字孪生模型与物理实体间同步控制的一致性、动作映射的实时性,实现了光学位移台运动状态的可视化监测功能.此外,设置的运动数据类型可满足微米级的信息传递,保证了光学位移台使用时的精度要求;同时虚拟控制面板各功能正常运行,提升了光学位移台控制的便利性.

In this study, we used a novel method of laser machining combined with dynamic chemical liquid etching (LMDCE) to drill holes in 2.5D SiCf/SiC ceramic matrix composites (CMC-SiC). A chemical solution that could quickly remove the recast layer without damaging the substrate was selected. Severe recast layer and microcrack defects were observed when laser machining was performed in the air. The surface of the material was highly carbonized due to the thermal effect of the laser. The effect of different defocus amounts and scanning speeds on the hole taper was studied. A lower scanning speed can ensure that a smaller taper is obtained by the microhole. The bore diameter of the holes processed with a defocusing amount of 0 or -1 mm is more uniform. The results show that with the assistance of a dynamic chemical solution, the fibers break neatly into needle-like shapes, the thermal effect of the laser on the ceramic substrate is significantly weakened, the microhole shows good roundness, and there are no recast layers and oxides on the sample surface. In addition, microcracks are significantly reduced, and high-quality microholes without a heat-affected zone (HAZ) are machined. The method provides a new idea on how to eliminate machining defects and achieve higher-quality micromachining for ceramic matrix composites.

In this paper, a zooming relationship for holographic parallel laser foci with the fractional Fourier transform is revealed and optimized, which is beneficial for accurate control of the microfabrication of structures and micropatterning of material surfaces. Using a spatial light modulator (SLM) and a dedicated computer-generated hologram (CGH), a single Gaussian beam can be modulated into multiple laser foci to improve the microprocessing efficiency. As a new extension of fractional Fourier holography, the adjustment of the multifocal position and the detail scaling of the design target by different fractional orders was investigated by means of theoretical analysis and numerical simulation. The processing experiments for microwire pairs on a glass surface verify that the consistency between parallel microstructures is jointly determined by sampling intervals and fractional orders. Then, zooming optimization was performed for the precise and rapid patterning of indium tin oxide (ITO) films. The fractional holographic parallel laser multifocus processing method shows great potential for the processing of multilayer structural materials and complex surface topography.