A review of ultrafast laser micro/nano fabrication:Material processing,surface/interface controlling,and devices fabrication

Ultrafast laser processing technology has offered a wide range of opportunities in micro/nano fabrication and other fields such as nanotechnology,biotechnology,energy science,and photonics due to its controllable processing precision,diverse processing capabilities,and broad material adaptability.The processing abilities and applications of the ultrafast laser still need more exploration.In the field of material processing,controlling the atomic scale structure in nanomaterials is challenging.Complex effects exist in ultrafast laser surface/interface processing,making it difficult to modulate the nanostructure and properties of the surface/interface as required.In the ultrafast laser fabrication of micro functional devices,the processing ability needs to be improved.Here,we review the research progress of ultrafast laser micro/nano fabrication in the areas of material processing,surface/interface controlling,and micro functional devices fabrication.Several useful ultrafast laser processing methods and applications in these areas are introduced.With various processing effects and abilities,the ultrafast laser processing technology has demonstrated application values in multiple fields from science to industry.

Localized in‑situ deposition:a new dimension to control in fabricating surface micro/nano structures via ultrafast laser ablation

Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.

Electrons dynamics control by shaping femtosecond laser pulses in micro/nanofabrication: modeling, method, measurement and application

During femtosecond laser fabrication,photons are mainly absorbed by electrons,and the subsequent energy transfer from electrons to ions is of picosecond order.Hence,lattice motion is negligible within the femtosecond pulse duration,whereas femtosecond photon-electron interactions dominate the entire fabrication process.Therefore,femtosecond laser fabrication must be improved by controlling localized transient electron dynamics,which poses a challenge for measuring and controlling at the electron level during fabrication processes.Pump-probe spectroscopy presents a viable solution,which can be used to observe electron dynamics during a chemical reaction.In fact,femtosecond pulse durations are shorter than many physical/chemical characteristic times,which permits manipulating,adjusting,or interfering with electron dynamics.Hence,we proposed to control localized transient electron dynamics by temporally or spatially shaping femtosecond pulses,and further to modify localized transient materials properties,and then to adjust material phase change,and eventually to implement a novel fabrication method.This review covers our progresses over the past decade regarding electrons dynamics control(EDC)by shaping femtosecond laser pulses in micro/nanomanufacturing:(1)Theoretical models were developed to prove EDC feasibility and reveal its mechanisms;(2)on the basis of the theoretical predictions,many experiments are conducted to validate our EDC-based femtosecond laser fabrication method.Seven examples are reported,which proves that the proposed method can significantly improve fabrication precision,quality,throughput and repeatability and effectively control micro/nanoscale structures;(3)a multiscale measurement system was proposed and developed to study the fundamentals of EDC from the femtosecond scale to the nanosecond scale and to the millisecond scale;and(4)As an example of practical applications,our method was employed to fabricate some key structures in one of the 16 Chinese National S&T Major Projects,for which electron dynamics were measured using our multiscale measurement system.

Ultrashort pulsed laser induced complex surface structures generated by tailoring the melt hydrodynamics

We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation.The pulse train used,in particular,consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning(DLIP).The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow,while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained.Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies.The underlying physical processes behind the complex patterns’generation were interpreted in terms of a multiscale model combining electron excitation with melt hydrodynamics.We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.

激光直写制备衍射光学元件的研究及应用

衍射光学元件作为一种典型的微光学元件,其体积小、质量轻、设计自由度多、成像质量良好,在光学成像、光学数据存储、激光技术、生物医学等领域具有广阔的应用前景。随着现代光学系统的不断发展,对衍射光学元件的加工效率和制备精度提出了更高的要求。激光直写技术凭借加工精度高、工艺简单、灵活性好等优势,成为制备高精密仪器中关键光学元件所必需的一种加工方式。针对不同的加工需求,开发了多种激光直写系统,并在应用过程中不断地改进升级。另外,突破衍射极限的飞秒激光微纳结构制造技术,能够获得更高的加工精度和更好的分辨率,为微光学元件的制备提供了新的方法。首先介绍了激光直写技术的特点;其次综述了衍射光学元件直写加工技术的研究进展,包括直写技术的影响因素、激光直写系统和多光束加工技术;接着介绍了衍射光学元件的典型应用,如红外成像、色差校正、光束整形、图像显示;最后,对激光直写技术制备衍射光学元件存在的问题和未来发展趋势做出了总结。

液体辅助激光加工硬脆材料及其应用

硬脆材料由于具有稳定的机械和化学性能、优良的光电特性等优势,在航空航天、光电工业等领域具有广泛的应用。激光加工由于具有高精度、高能量、非接触式加工等特点,是实现硬脆材料加工的理想技术。为了实现硬脆材料的去除加工,通常需要较高的激光能量,使得加工的结构精度较低,而且表面质量较差。本综述介绍了液体辅助激光加工技术在硬脆材料加工方面的研究进展,分别介绍了液相激光烧蚀、激光诱导背部湿法刻蚀和刻蚀辅助激光改性等三种液体辅助激光加工技术的原理,对比了各自的优势和不足,以及不同加工技术、辅助液体种类以及加工参数等对不同硬脆材料加工质量的影响,介绍了液体辅助激光加工技术目前主要的应用,最后,简要阐述了该技术存在的问题和未来的潜在发展。

超快激光制造表面增强拉曼散射传感器

表面增强拉曼散射(SERS)传感器在诸多领域拥有重要的应用潜力。为实现高精度SERS检测,增加热点密度和热点区域中分析物分子数量成为当前研究的重点。超快激光可快速在材料表面构筑大面积的微纳米结构,对于高性能SERS基底的商业化制备具有重要的意义。本文从热点密度和检测区域中分析物分子浓度两个方面,总结了近年来超快激光制造高性能SERS基底的工艺方法。超快激光既能“自下而上”,也能“自上而下”加工出具有局域场增强效应的微纳米结构。其中,超快激光制备的超疏水表面是目前实现待测分子富集的有效方法之一。最后展望了激光制备SERS基底的应用前景。

飞秒激光湿法刻蚀微纳制造

飞秒激光微加工作为一种新型微纳制造技术,在复杂三维构型制作方面具有其独特的优势,但激光加工效率问题严重制约了飞秒激光微加工技术走向实际工程应用,提出一种飞秒激光湿法刻蚀微纳制造方法,以提高飞秒激光微加工的效率为突破口,通过调控激光与物质相互作用获得材料的目标靶向改性,进而结合化学湿法刻蚀实现硬质材料上的高效和高精度三维微加工,采用这一方法制作出的微透镜尺寸为80μm,球冠高6.7μm,表面粗糙度小于10nm。利用这种方法,实现了不同结构与特性的高质量微透镜阵列的超精密制备,在石英内部也实现了螺旋微通道的复杂三维结构,螺旋通道直径为20μm,长径比超过100。

激光超衍射加工机理与研究进展

随着纳米科技和微纳电子器件的发展,制造业对微纳加工技术的要求越来越高.激光加工技术是一种绿色先进制造技术,具有巨大的发展潜力,己广泛应用于不同的制造领域.为实现低成本、高效率、大面积尤其是高精度的激光微纳加工制造,研究和发展激光超衍射加工技术具有十分重要的科学意义和应用价值.本文首先阐述了基于非线性效应的远场激光直写超衍射加工技术的原理与国内外发展状况,包括激光烧蚀加工技术、激光诱导改性加工技术和多光子光聚合加工技术等;然后介绍了几种基于倏逝波的近场激光超衍射加工技术,包括扫描近场光刻技术、表面等离子激元光刻技术等新型超衍射激光近场光刻技术的机理与研究进展;最后对激光超衍射加工中存在的问题及未来发展方向进行了讨论.

凝聚态物质的近红外飞秒激光微纳制备

利用近红外飞秒激光脉冲对玻璃和聚合物等透明凝聚态物质进行微纳制备.通过飞秒激光诱导的折射率变化在石英玻璃内部制备光栅等折射率型元器件;从后表面开始钻孔并引入蒸馏水,在钠钙玻璃中加工出纵横比很大的微细直孔;改变飞秒双光子聚合中激光焦点在样品中的位置,聚合出直线型和波浪型等不同形状的线条.

光纤激光诱导背面干法刻蚀制备二元衍射光学元件

为了降低激光直接辐照透明介电材料的表面加工粗糙度和激光能量密度刻蚀阈值,提高微光学元件的产出率,介绍了一种用固体介质作吸收层,激光直接作用在透明光学材料上进行微纳加工的激光诱导背面干法刻蚀工艺。首先,选用95氧化铝陶瓷作固体材料辅助吸收层,应用中心波长为1 064nm的掺镱光纤激光器,在3.2mm厚的熔融石英玻璃表面刻蚀了亚微米尺度的二维周期性光栅结构。然后,对刻蚀参数进行拟合并探讨了激光能量密度对刻蚀参数的影响。最后,观察该二元光学元件的衍射花样图形并讨论其衍射特性。实验制备了槽深为4.2μm,槽底均方根粗糙度小于40nm,光栅常数为25μm的二维微透射光栅,其刻蚀阈值低于7.66J/cm2。结果表明,应用该工艺制备二维透射光栅,降低了激光刻蚀透明材料的密度阈值及加工结构的表面粗糙度。

新型光刻技术研究进展

集成电路光刻作为传统光刻技术的典型代表,支撑着集成电路芯片的快速发展。新一代光刻技术具有工艺多样化、光刻精度高、光刻效率高的优点,在研发新型光电子器件、实现3维微纳结构、构建有序纳米孔通道等方面有很大的潜力。回顾了近些年来涌现的多种新型光刻技术,分析了各自的特征及在新型纳米电子、光子器件、能源、传感等领域中的应用。对未来光刻技术的发展方向进行了展望。

飞秒激光刻蚀增强非晶硅薄膜太阳电池性能的研究

通过恒速移动线偏振飞秒激光焦点对非晶硅(a-Si)pin型薄膜太阳电池n型硅膜表面进行绒化刻蚀处理,形成不同周期间隔"凹槽"状结构。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对刻蚀后薄膜表面形貌进行了表征,证实了刻蚀区域表面能够诱导晶态多孔微结构形成。比较了飞秒激光刻蚀前后a-Si太阳电池的光电转换效率(η)、开路电压、短路电流密度和填充因子。结果表明,当飞秒激光脉冲能量为0.75 J/cm^2、刻蚀周期间隔为15μm时,太阳电池光电转换效率达到14.9%,是未经过激光刻蚀处理电池光电转换效率的1.87倍。同时,反射吸收谱表明,电池表面多孔"光俘获"微结构的形成对其光电转换效率的提高起到了关键作用。

非线性激光制造的进展与应用(特邀)

超快激光是指脉冲宽度极窄的激光,其瞬时功率极高,与物质之间的相互作用呈现出非线性、非平衡、多尺度的状态。超快激光具有超快(脉冲持续时间短)、超强(瞬时功率高)、超精细(加工结构精细)等特点,由此实现的非线性激光制造技术可以打破传统微纳制造的局限,实现各类难加工材料和复杂微纳结构的超精细制造,精度可达亚微米至纳米量级,在微光学、生物医学、智能电子器件等前沿领域体现出了独特的应用价值。文中主要聚焦飞秒激光微纳加工技术前沿,简要概括了飞秒激光加工的特点;介绍了飞秒激光加工的主要技术手段,包括飞秒激光直写和飞秒激光并行加工;讨论了飞秒激光加工技术的前沿应用领域,如微纳光学器件、微流体器件、多功能结构化表面、生物医学工程等;最后,对飞秒激光加工制造技术未来的发展趋势和研究方向进行展望。

飞秒激光制备柔性电子器件进展

消费电子市场正推动柔性电子器件向集成化、小型化及可穿戴的方向发展,同时也对柔性电子器件的制备提出了新的要求。光刻工艺加工精度高,但其成本昂贵、加工流程复杂且效率低。相比而言,飞秒激光加工兼有加工精度高和工艺流程简单的特点,已展现在制备柔性电子器件方面的独特优势和应用前景。为了更好地了解这一新兴领域的进展,本文概述了与柔性电子器件制备相关的五种飞秒激光加工工艺机理,包括激光液相纳米材料合成、激光纳米材料还原、激光诱导纳米连接、激光电极图案化及激光表面织构化,并介绍了制备的典型柔性电子器件性能,对存在的问题和未来发展趋势进行了分析和展望。

二维光栅制备及衍射特性研究

利用飞秒激光微加工平台,结合激光直写技术,在50 nm厚的金膜上制备出了二维光栅,研究了扫描速度和扫描间距固定时,飞秒激光能量密度的改变对二维光栅结构的影响。通过扫描电子显微镜(Scanning Electron Microscopy,SEM)对制备的二维光栅的形貌进行表征,并准确测量了光栅参数。利用氦氖激光分析了二维光栅的衍射效果,并与数值模拟得到的图案进行比较,分析了条纹缝宽和栅格尺寸对衍射点阵列光强分布的影响。研究表明飞秒激光直写技术可以方便快速地通过加工参数的改变制备不同尺寸分布的二维光栅。

激光微纳制造太阳能海水淡化材料研究进展

海水淡化技术在解决水资源短缺的问题上起着重要的作用,其中太阳能海水技术的研究#更是备受关注。激光微纳制造技术作为一种先进、便捷的加工方法,近年来在制备海水淡化材料领域取得了一定的研究成果。本文以太阳能海水淡化技术以及激光加工技术作为研究背景,根据研究材料的多样性,从材料的构成本质出发,将近年来关于激光微纳制造海水淡化材料的研究分为碳基类、金属基类和复合基类材料三个部分来进行阐述,最后结合当前研究,阐明该方向面临的挑战并对其前景进行展望。

激光诱导空化微纳制造实验研究

概述了激光微纳制造应用前景。通过单脉冲激光作用在水中,击穿水的阈值产生空化作用,从而在铝板上制造出了孔状的微纳结构。并且应用高速摄影仪和水听计分析了其制造机理,主要为微射流和等离子冲击波共同作用的结果。最后,提出了激光诱导空化微纳制造在表面结构微纳成型具有较好的定域性,但是表面控形和不同位置加工机理需要进一步探索研究。

Characteristic control of long period fiber grating （LPFG） fabricated by infrared femtosecond laser

Long period fiber gratings （LPFGs） with different spectral characteristics were fabricated with 1 kHz, 50 fs laser pulses. The contrast of resonant rejection band can be significantly increased by a proper amount of axial stress along a fiber during laser writing or post- processing with lower energy density laser irradiation. Variations of focal condition, pulse energy of laser irradiation and the number of grating periods lead to the generation of resonance rejection band of LPFGs from single-peak to multi-peak plus larger out-of-band loss. The out-of-band loss is primarily caused by Mie scattering from the laser processed cites, and it can be reduced by decreasing the duty cycle of grating pitch instead of lowing down the actual power of laser irradiation.

面向激光微纳加工的柔性XY平台设计与分析

针对激光微纳加工设备中传统机械式的微位移机构运动方向单一而柔性铰链本身驱动又存在驱动位移小的问题,设计了一种柔性大行程完全解耦的XY微纳运动平台;推导了杠杆位移放大器的放大比率模型,通过粒子群优化算法对运动平台的尺寸进行优化分析。运用ANSYS分析软件,对所设计平台的静力学、动力学性能进行分析。仿真结果表明:该平台具有良好的解耦特性,能够满足机构的两自由度运动解耦要求。