共查询到20条相似文献,搜索用时 15 毫秒
1.
Haifeng Yang Haidong He Enlan Zhao Jiguo Qian Jingbin Hao Wei Tang Hua Zhu 《Journal of Russian Laser Research》2013,34(4):362-368
We report on the fabrication of surface nanoparticles and micro/nanograting structures on bulk pure aluminum in air using a 150 fs, 775 nm femtosecond laser. We investigate the size of the generated surface nanoparticles under irradiation with different femtosecond laser pulses. Smaller nanoparticles can be induced by a larger number of laser pulses and a lower laser fluence. In addition, we observe the formation of micro/nanogratings when the laser focus is scanned across a pure aluminum surface in air. We obtain micro- and nano-grating composite structures on a pure aluminum surface by adjusting the laser fluence and scan velocity. Femtosecond laser surface ablation of bulk pure aluminum in air is potentially a promising technique for efficient fabrication of surface nanostructures. 相似文献
2.
Coherent linking of periodic nano-ripples on a ZnO crystal surface induced by femtosecond laser pulses 总被引:1,自引:0,他引:1
X. D. Guo R. X. Li Y. Hang Z. Z. Xu B. K. Yu Y. Dai B. Lu X. W. Sun 《Applied Physics A: Materials Science & Processing》2009,94(2):423-426
We demonstrate the coherent linking of periodic nano-ripples formed on the surface of ZnO crystals induced by femtosecond
laser pulses. By adjusting the distance between two laser scanning zones, the periodic nano-ripples induced by two separated
laser writing processes can be coherently linked and the ZnO nanograting with much longer grooves is therefore produced. The
length limitation of this kind of nanograting previously set by the laser focus size is thus overcome. The micro-Raman mapping
technique is used to evaluate the quality of coherent linking, and the underlying physics is discussed. The demonstrated scheme
is promising for producing large-size self-organized nanogratings induced by femtosecond laser pulses. 相似文献
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4.
Tightly focused, linearly polarized, femtosecond laser radiation can produce highly birefringent nanograting structures inside fused silica glass. Here we report that when the polarization direction of the femtosecond light is changed, old nanogratings are erased and simultaneously replaced with new ones whose orientation is solely determined by the polarization of the rewrite beam. We also show that these volume nanogratings can be rewritten 1000 times with little degradation in their quality. 相似文献
5.
A. Schmidt F. Garwe U. Hübner T. May W. Paa M. Zeisberger G. Zieger H. Stafast 《Applied physics. B, Lasers and optics》2012,109(4):631-642
The THz radiation emission of Au-coated nanogratings (fused silica substrate, 30?nm Au layer thickness, 500?nm grating constant) upon fs laser irradiation (785?nm, 150?fs, 1?kHz,???1?mJ/pulse) is observed in both directions along the laser beam axis (forward and backward) and for both, illumination of the Au/air or the Au/silica interface. THz radiation along the laser beam propagation is emitted in a narrow solid angle of about 15°?fwhm independent on the laser pulse fluence, the angle of incidence and the nanograting profile. The bar width and groove depth of the nanograting as well as the angle of laser beam incidence strongly affect the THz radiation yield. The energy of single THz light pulses is measured absolutely (2?fJ in the 0.3?C0.38?THz range) using a highly sensitive and fast superconducting transition edge sensor. The bi-directional emission of THz radiation is in agreement with the model assumption of surface plasmon polaritons propagating simultaneously on both Au layer interfaces (Au/air and Au/silica). 相似文献
6.
Shazia Bashir M. Shahid Rafique Ali Ajami Wolfgang Husinsky Umm-i-Kalsoom 《Applied Physics A: Materials Science & Processing》2013,113(3):673-681
The present work deals with growth of nanoscale periodic and dot-like structures on the surface of stainless steel (SS) by the irradiation of femtosecond laser pulses. For this purpose Ti: Sapphire femtosecond laser pulses (wavelength of 800 nm, pulse length of 25 fs and pulse repetition rate of 1 kHz) were employed in a dry (air) and liquid confined (deionized water and ethanol) environments. The targets were exposed to 1000 succeeding pulses for various fluences ranging from 50 to 150 mJ?cm?2. Nanoscale structures including ripples, and dots were observed by SEM analysis. The growth and dependence of structure-formation on the ambient environment and laser fluence in both central as well as peripheral ablated areas is systematically investigated. The development of nanostructures and nanoripples is correlated with structural analysis carried out by micro Raman spectroscopy. 相似文献
7.
Zhihua Li Haixia Li Jingyu Zhang Shan Chen Mingtao Huang Xiaoling Yu 《Optics & Laser Technology》2012,44(4):923-928
Self-organized nanoripples are induced on bulk metal Cu and Ag by femtosecond laser, and the influence of number of shots on nanostructure formation has been investigated. The AFM images show that obtained grooves on Cu are about 50 nm deep, and have an average spacing of 481.41 nm, which is smaller compared to the incident radiation wavelength (800 nm). Arrays of ablated craters are machined on Cu and Ag surfaces by femtosecond laser in order to determine the optical characteristics of laser irradiated surface. Compared with that of untreated sample, the locations of maximum absorption wavelength of laser treated samples are not shifted, while average absorbance intensities are enhanced both for modified Ag and Cu surfaces. Finally, the effects of thermal conductivity, dielectric function as well as electron–phonon coupling coefficient on nanograting morphology induced by femtosecond laser are discussed qualitatively. 相似文献
8.
N. G. Semaltianos W. Perrie P. French M. Sharp G. Dearden S. Logothetidis K. G. Watkins 《Applied Physics A: Materials Science & Processing》2009,94(4):999-1009
Femtosecond laser (180 fs, 775 nm, 1 kHz) ablation characteristics of the nickel-based superalloy C263 are investigated. The
single pulse ablation threshold is measured to be 0.26±0.03 J/cm2 and the incubation parameter ξ=0.72±0.03 by also measuring the dependence of ablation threshold on the number of laser pulses.
The ablation rate exhibits two logarithmic dependencies on fluence corresponding to ablation determined by the optical penetration
depth at fluences below ∼5 J/cm2 (for single pulse) and by the electron thermal diffusion length above that fluence. The central surface morphology of ablated
craters (dimples) with laser fluence and number of laser pulses shows the development of several kinds of periodic structures
(ripples) with different periodicities as well as the formation of resolidified material and holes at the centre of the ablated
crater at high fluences. The debris produced during ablation consists of crystalline C263 oxidized nanoparticles with diameters
of ∼2–20 nm (for F=9.6 J/cm2). The mechanisms involved in femtosecond laser microprocessing of the superalloy C263 as well as in the synthesis of C263
nanoparticles are elucidated and discussed in terms of the properties of the material. 相似文献
9.
The influence of different laser pulse lengths on the removal of a polymer layer from metal substrates was investigated. As model systems, doped poly(methylmetacrylate) (PMMA) on titanium and tungsten substrates were selected.The ablation threshold and irradiation spot morphology of titanium and tungsten were compared for femtosecond (fs) and nanosecond (ns) laser irradiation and different pulse numbers. Nanosecond laser treatment resulted in a non-homogeneous surface morphology for both titanium and tungsten substrates. Femtosecond irradiation of tungsten revealed a homogeneous ablation spot with little changes in the surface morphology. For titanium, the formation of columnar structures within the irradiation spot was observed.Two different dopant concentrations were used for PMMA to achieve an equal linear absorption coefficient for the femto- and nanosecond laser wavelengths of 790 and 1064 nm. The best results were achieved for the removal of doped PMMA by femtosecond laser irradiation, where only a minimal modification of the metal surface was detected. In the case of nanosecond laser exposure, a pronounced change of the structure was observed, suggesting that damage-free cleaning of the selected metal may only be possible using femtosecond laser pulses. Different experimental parameters, such as laser fluence, pulse repetition rate and sample speed were also investigated to optimize the cleaning quality of doped PMMA from tungsten substrates with femtosecond laser pulses. 相似文献
10.
Electron dynamics and prompt ablation of aluminum surface excited by intense femtosecond laser pulse
A. A. Ionin S. I. Kudryashov S. V. Makarov L. V. Seleznev D. V. Sinitsyn 《Applied Physics A: Materials Science & Processing》2014,117(4):1757-1763
Thin aluminum film homogeneously heated by intense IR femtosecond laser pulses exhibits on the excitation timescale consequent fluence-dependent rise and drop of the IR-pump self-reflectivity, followed by its final saturation at higher fluences F > 0.3 J/cm2. This prompt optical dynamics correlates with the initial monotonic increase in the accompanying laser-induced electron emission, which is succeeded by its non-linear (three-photon) increase for F > 0.3 J/cm2. The underlying electronic dynamics is related to the initial saturation of IR resonant interband transitions in this material, followed by its strong instantaneous electronic heating via intraband transitions during the pump pulse resulting in thermionic emission. Above the threshold fluence of 0.3 J/cm2, the surface electronic heating is balanced during the pump pulse by simultaneous cooling via intense plasma removal (prompt ablation). The relationship between the deposited volume energy density in the film and its prompt electronic temperature derived from the self-reflection measurements using a Drude model, demonstrates a kind of electron “liquid–vapor” phase transition, driven by strong cubic optical non-linearity of the photo-excited aluminum. 相似文献
11.
L. Englert M. Wollenhaupt L. Haag C. Sarpe-Tudoran B. Rethfeld T. Baumert 《Applied Physics A: Materials Science & Processing》2008,92(4):749-753
Laser material processing of dielectrics with temporally asymmetric femtosecond laser pulses of identical fluence, spectrum,
and statistical pulse duration is investigated experimentally. To that end single shot structures at the surface of fused
silica as a function of fluence and pulse shape are analyzed with the help of scanning electron microscopy. Structures for
the bandwidth limited pulses show the known expansion in structure size with increasing laser fluence approaching the diffraction
limit, which is 1.4 μm for the 0.5NA microscope objective used. In contrast, structures from the asymmetric pulses are remarkably
stable with respect to variations in laser fluence and stay below 300 nm despite doubling the fluence. Different thresholds
for surface material modification with respect to an asymmetric pulse and its time reversed counterpart are attributed to
control of different ionization processes. 相似文献
12.
Yang Liao Bin Zeng Lingling Qiao Lianqing Liu Koji Sugioka Ya Cheng 《Applied Physics A: Materials Science & Processing》2014,114(1):223-230
Recently, femtosecond laser direct writing in porous glass is emerging as a powerful technique for building arbitrary 3D hollow micro/nanostructures in bulk glass materials. In this study, we investigate the pulse duration dependence of laser intensity window for inducing a single nanocrack inside porous glass by femtosecond laser direct writing. We find that the window for a single nanocrack increases with the pulse duration, while the roughness of side walls in the nanocracks becomes higher for pulses longer than ~300 fs. When the femtosecond laser pulses of an optimized duration of ~200 fs are chosen, a sufficiently broad range of laser intensity (~44 % of the structuring threshold) for creating a single nanocrack can be obtained, while smooth sidewalls required by nanofluidic applications can still be maintained. The reported results will be beneficial not only for the development of the 3D femtosecond laser micro/nanostructuring techniques, but also for gaining a deeper understanding of the physical mechanism behind the nanograting formation induced by femtosecond laser irradiation in glass and other transparent materials. 相似文献
13.
Weiwei Liang Feng Chen Hao Bian Qing Yang Xianhua Wang Jinhai Si Xun Hou 《Optics Communications》2010,283(11):2385-2389
Periodic surface nanostructures induced by femtosecond laser pulses on polycrystalline ZnO are presented. By translating the sample line-by-line under appropriate irradiation conditions, grating-like nanostructures with an average period of 160 nm are fabricated. The dependence of surface morphologies on the processing parameters, such as laser fluence, pulse number and laser polarization, are studied by scanning electronic microscope (SEM). In addition, photoluminescence (PL) analysis at room-temperature indicates that the PL intensity of the irradiated area increases significantly compared with the un-irradiated area. Using femtosecond laser pulses irradiation to fabricate periodic surface nanostructures on polycrystalline ZnO is efficient, simple and low cost, which shows great potential applications in ZnO-based optoelectronic devices. 相似文献
14.
We successfully fabricated a high-performance half-wave plate for the 405 nm wavelength based on monolithic integration of two nanograting layers. Each of the nanograting layers functions as a quarter-wave plate. Both of the nanograting layers were fully filled and planarized to achieve the monolithic integration. UV-nanoimprint lithography, along with thin-film deposition, high-aspect-ratio reactive ion etching, and trench-filling technologies, was used in fabrication and integration of the individual nanograting layers. High-aspect-ratio nanogratings with sub-50 nm linewidths and 100 nm spacing were fabricated to achieve good optical performance at the near-UV wavelength. The ability to integrate multiple nanostructure-based optical layers opens a path for integrated multifunction devices, as well as a new strategy for driving both miniaturization and cost. 相似文献
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16.
E. Fadeeva J. Koch B. Chichkov A. Kuznetsov O. Kameneva N. Bityurin C. Sanchez A. Kanaev 《Applied Physics A: Materials Science & Processing》2006,84(1-2):27-30
First results on femtosecond laser 3D-microstructuring are reported in a novel class of organic-inorganic hybrid materials based on titanium oxide gels. Transparent optical-grade polished hybrid samples demonstrate strong photosensitivity assigned to electrons trapped as Ti3+ centers. Two different regimes of the microstructuring are observed: reversible and irreversible. In tight-focusing conditions using “on-the-fly” technique the single-pulse microstructuring is achieved with nanojoule laser pulses. The process thresholds have been studied on the surface and into the bulk of the material with irradiation by 1, 2, 10, and 100 laser pulses. A reduction of the damage threshold fluence by a factor of 2.5 is observed when increasing exposure from 1 pulse (1.2 J/cm2) to 100 pulses (0.5 J/cm2). PACS 42.62.-b; 40.70.-a; 78.66.Sq 相似文献
17.
E. V. Golosov A. A. Ionin Y. R. Kolobov S. I. Kudryashov A. E. Ligachev S. V. Makarov Y. N. Novoselov L. V. Seleznev D. V. Sinitsyn 《Applied Physics A: Materials Science & Processing》2011,104(2):701-705
Gradual evolution of self-induced silicon surface topology from one-dimensional ridge-like to two-dimensional spike-like nanogratings
and then to isotropic sets of micro-columns was observed by evenly increasing IR and UV femtosecond laser irradiation dose.
This topological evolution exhibits clear indications of consequent melting and vaporization processes being set up during
the prolonged laser irradiation. Monotonously decreasing cumulative IR and UV femtosecond laser-nanostructuring thresholds
may indicate an increase of optical absorbance of the laser-nanostructured silicon surfaces versus the increasing laser dose,
consistent with the consequent onset of the abovementioned thermal modification processes. 相似文献
18.
Fundamental mechanism of femtosecond-laser-induced periodic surface nanostructure formation has been investigated under the condition using superimposed multiple shots at lower fluence than the single-pulse ablation threshold. With increasing the shot number of low-fluence fs-laser pulses, the periodic nanostructure develops through the bonding structure change of target material, the nanoscale ablation with optical near-fields induced around the high curvatures, and the excitation of surface plasmon polaritons (SPPs) to create the nano-periodicity in the surface structure. It is confirmed that non-thermal interaction at the surface plays the crucial role in the nanostructure formation. Based on the mechanism, we have demonstrated that the periodic nanostructure formation process can be controlled to fabricate a homogeneous nanograting on the target surface, using a two-step ablation process in air. The experimental results obtained represent exactly the nature of a single spatial standing SPP wave mode that generates periodically enhanced near-fields for the nanograting formation. The calculated results for a model target reproduce well the nanograting period and explain the characteristic properties observed in the experiment. 相似文献
19.
研究了800nm飞秒激光照射下45°高反膜ZrO2-Si O2的破坏及其超快动力学过程。利用原子力显微镜和扫描电镜观察了材料的烧蚀形貌,测量了破坏阈值与脉冲宽度、烧蚀深度与脉冲能量的依赖关系。随着脉冲宽度从50fs增加到900fs,其烧蚀阈值从0.35J/cm2增加到1.78J/cm2。烧蚀深度与激光能流密度近似成对数关系。当激光强度略高于烧蚀阈值时,材料很快被烧蚀到几百纳米,烧蚀深度表现出明显的层状特性。同时,利用建立的抽运探针实验系统,测量了高强度抽运脉冲作用下材料对探针光的反射率随延迟时间的变化,揭示了薄膜烧蚀的超快动力学过程。实验结果表明高反膜表层的材料对烧蚀特性有重要影响。 相似文献
20.
飞秒激光的波长对SiC材料烧蚀的影响 总被引:10,自引:0,他引:10
利用10倍的显微物镜将近红外飞秒激光脉冲汇聚到宽带隙半导体材料6H SiC的前表面,研究样品的烧蚀及诱导微细结构。用扫描电镜(Scanning electron microscope,SEM)及光学显微镜测量烧蚀斑。利用烧蚀面积与激光脉冲能量的关系确定SiC的烧蚀阈值。给出了SiC样品的烧蚀阈值与飞秒激光波长的依赖关系。实验结果表明,可见光区随波长增加,烧蚀阈值从0.29J/cm2增加到0.67J/cm2;而在近红外区,SiC的烧蚀阈值为0.70J/cm2左右,基本上不随激光波长变化而改变。结合计算结果,可以认为在飞秒激光烧蚀SiC的过程中,在近红外区,光致电离和碰撞电离均起到了重要的作用;而在可见光区,光致电离的作用相对大一些。 相似文献