共查询到20条相似文献,搜索用时 31 毫秒
1.
Taek Yong Hwang A. Y. Vorobyev Chunlei Guo 《Applied Physics A: Materials Science & Processing》2012,108(2):299-303
Through femtosecond (fs) laser pulse irradiation, we produce two-dimensional quasiperiodic arrays of nanostructure-covered conical microstructures (NC-CMs) on Ni. We also find that a significant amount of nickel oxide covers NC-CMs owing to the interaction of fs laser pulses with Ni in ambient air. We show that, by controlling the fluence of laser, the reflectance of the fs laser-treated Ni surface can change dramatically in the infrared but the surface still has a high absorptance at UV and visible wavelengths. Because of this unique spectral reflectance, the fs laser-treated Ni surface is well suited for use as a solar absorber surface. 相似文献
2.
Through femtosecond (fs) laser pulse irradiation (pulse duration: 65 fs, central wavelength: 800 nm, and repetition rate: 250 Hz), we investigate the morphological evolution of fs laser-induced periodic surface structure on Au and Pt, called a nanostructure-covered large-scale wave (NC-LSW) with a period of tens of microns, densely covered by iterating stripe patterns of nanostructures and microstructures. We show that the surface morphology of NC-LSW crucially depends on the fluence of the laser, the number of irradiating pulses, and the incident beam angle. Our experimental observations allow us to establish a three-step model for the NC-LSW formation: the formation of laser-induced surface unevenness, inhomogeneous energy deposition due to the interference between the incident light and the scattered field, and nonuniform energy deposition due to shielding by the peaks of LSW. 相似文献
3.
Hong-Dao Yang Xiao-Hong Li Guo-Qiang Li Cai Wen Rong Qiu Wen-Hao Huang Jun-Bo Wang 《Applied Physics A: Materials Science & Processing》2011,104(2):749-753
A single-crystal silicon(111) wafer surface fixed on an x–y translation stage is scanned with a focused femtosecond laser beam at a wavelength of 800 nm under different atmospheres
(air, vacuum, and nitrogen). Different colors from different angles on the surface of the silicon then appear. From the result
of the experiments, periodic ripple surface structures emerge on the surface of colorized silicon, and the phenomenon is more
obvious in vacuum and nitrogen than in air. The periods of the surface structures on silicon are not the same in the different
atmospheres. Under vacuum, the period is the longest and is closer to the wavelength of the laser irradiation. Different from
metals, the range of energy density is smaller when the colorized silicon appears with femtosecond laser pulses. Through SEM,
TEM, and AFM, we observe in detail the microstructures of colorized silicon that forms in air, vacuum, and nitrogen and analyze
the possible physical mechanism. Finally, research into the optical reflection of the colorized silicon indicates that the
reflectivity is not higher than 30% in the 250–800 nm range. 相似文献
4.
This paper reviews a new field of direct femtosecond laser surface nano/microstructuring and its applications. Over the past few years, direct femtosecond laser surface processing has distinguished itself from other conventional laser ablation methods and become one of the best ways to create surface structures at nano‐ and micro‐scales on metals and semiconductors due to its flexibility, simplicity, and controllability in creating various types of nano/microstructures that are suitable for a wide range of applications. Significant advancements were made recently in applying this technique to altering optical properties of metals and semiconductors. As a result, highly absorptive metals and semiconductors were created, dubbed as the “black metals” and “black silicon”. Furthermore, various colors other than black have been created through structural coloring on metals. Direct femtosecond laser processing is also capable of producing novel materials with wetting properties ranging from superhydrophilic to superhydrophobic. In the extreme case, superwicking materials were created that can make liquids run vertically uphill against the gravity over an extended surface area. Though impressive scientific achievements have been made so far, direct femtosecond laser processing is still a young research field and many exciting findings are expected to emerge on its horizon. 相似文献
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J. J. J. Kaakkunen K. Paivasaari M. Kuittinen T. Jaaskelainen 《Applied Physics A: Materials Science & Processing》2009,94(2):215-220
Recently, the enhancing of bulk metals optical absorption with focused femtosecond pulses was demonstrated. This absorption
enhancement is caused by different nano- and micro-structures which are formed during laser ablation with ultrashort pulses.
In this paper we study the evolution of the surface structures using interferometric ablation and compare it to normal fs-ablation.
Previously we have shown that interferometric femtosecond ablation is an efficient method to fabricate absorbing metal surfaces.
In this study we ablated large areas of hole-array structures with different pulse numbers in polished stainless steel and
copper samples. The evolution of surface morphology and the depth of the holes for these structured surfaces are presented.
In addition, the reflectance of laser generated surface structures are measured at the wavelength range of 200–2300 nm using
a standard spectrophotometer. 相似文献
8.
C. Rosati D. Ciofini I. Osticioli R. Giorgi S. Tegli S. Siano 《Applied Physics A: Materials Science & Processing》2014,114(1):253-259
Femtosecond laser nano-processing by enhanced light scattered from nanospheres has received much attention. Enhanced scattered near field enables us to ablate nanoholes at nanometer scales below the diffraction limit. In addition, the interference between the scattered far field and the irradiated laser enables us to fabricate spatially controlled periodic surface structures. In this paper, we simulated the time evolution of scattered near field and far field during the free electron excitation in silicon (Si) by femtosecond laser irradiation. The optical property of Si changes from dielectric to metal-like Si due to the increase of the free electron number density excited by femtosecond laser pulse. It is elucidated that the scattered field of Si shifts from Mie scattering to plasmonic scattering during laser irradiation. We achieved the optimal free electron density and laser intensity for precisely controlled periodic surface structures fabrication. We explained the temporal behavior of the scattering near field and far field from the standpoint of dielectric function of the materials. 相似文献
9.
In this paper, we perform a shot-to-shot detailed study of how residual thermal energy correlates to the optical absorptance change due to laser-induced surface structural modifications in multi-shot femtosecond laser ablation. We observe an overall enhancement for residual thermal coupling and absorptance in air. Surprisingly, residual thermal coupling in air shows a non-monotonic dependence on pulse number and reaches a minimum value after a certain number of pulses, while these behaviors are not seen in absorptance. In vacuum, however, both suppression and enhancement are seen in residual energy coupling although absorptance is always enhanced. To explain these observations, we suggest that air plasma plays a dominant role in thermal coupling at a relatively low number of applied pulses, while the formation of a cavity plays a dominant role at a high number of pulses. PACS 78.20.Ci; 81.05.Bx 相似文献
10.
采用了不同能量的单脉冲和多脉冲飞秒激光对LiNbO3晶体进行烧蚀,并刻蚀了表面衍射型光栅.通过扫描电镜和原子力显微镜观察了烧蚀点的形貌特征,首次发现利用单束飞秒激光脉冲对LiNbO3晶体烧蚀,可以得到超衍射极限的烧蚀点,当聚焦光斑直径约为2μm、能量为170nJ的单脉冲飞秒激光作用时,烧蚀点的直径约为400nm,100nJ,17个脉冲作用时烧蚀点的直径约为800nm.同时可以观察到在能量较低的多脉冲飞秒激光作用下, LiNbO3晶体呈现出大约200nm周期性分布的波纹状结构.实验结果表明,选择合适参数的飞秒激光脉冲可以对LiNbO3晶体进行超衍射极限加工,这对于利用飞秒激光制作LiNbO3基质的微纳光电子器件有十分重要的意义. 相似文献
11.
We report on an unusual permanent recording of light helicity on optically achiral metals. Following a number of circularly polarized (CP) or elliptically polarized (EP) femtosecond laser pulses, well-defined periodic surface structures are found on metal surfaces. These surface structures show different orientation when formed by left CP/EP compared with right CP/EP light. The formation of these structures is attributed to the interference between the incident light and the excited surface plasmons. To our knowledge, this is the only phenomenon that can permanently record light helicity with an optically inactive material. 相似文献
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Surface texturing of the metals, including steels, gained a new dimension with the appearance of femtosecond lasers. These laser systems enable highly precise modifications, which are very important for numerous applications of metals. The effects of a Ti:sapphire femtosecond laser with the pulse duration of 160 fs, operating at 775 nm wavelength and in two operational regimes - single pulse (SP) and scanning regime, on a high quality AISI 1045 carbon steel were studied. The estimated surface damage threshold was 0.22 J/cm2 (SP). Surface modification was studied for the laser fluences of 0.66, 1.48 and 2.37 J/cm2. The fluence of 0.66 J/cm2, in both working regimes, induced texturing of the material, i.e. formation of periodic surface structures (PSS). Their periodicity was in accordance with the used laser wavelength. Finally, changes in the surface oxygen content caused by ultrashort laser pulses were recorded. 相似文献
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J. Koch F. Korte T. Bauer C. Fallnich A. Ostendorf B.N. Chichkov 《Applied Physics A: Materials Science & Processing》2005,81(2):325-328
Using tightly focused femtosecond laser pulses one can produce sub-micrometer holes and periodic structures in almost all solid materials. But with structure sizes below one micron, femtosecond laser structuring forfeits its universal character. In this paper we concentrate on the discussion of the influence of electron-phonon coupling strength in metal ablation morphology. In metals with weak electron-phonon coupling, results of femtosecond laser ablation can be dominated by solidified flow dynamics in molten material. One can make use of this phenomenon for ablation-free nanotexturing of gold films. PACS 42.62.-b; 42.65.Re; 52.38.hf 相似文献
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利用波长为800 nm的飞秒激光,在空气和去离子水中诱导钛表面形成不同的周期条纹结构。在空气中,激光能量密度为0.265 J/cm2时,钛表面主要形成周期为500~560 nm低空间频率条纹结构;激光能量密度为0.102 J/cm2时,主要形成的是周期为220~340 nm高空间频率条纹结构。两种条纹均垂直于入射激光偏振方向,且条纹周期随着脉冲重叠数的增大而增大。在水中,除形成垂直激光偏振方向、周期为215~250 nm的高空间频率条纹结构,还形成了平行于激光偏振方向且周期约为入射激光波长八分之一的高空间频率条纹结构。利用表面等离子体理论、二次谐波及Sipe理论对各种周期条纹结构的形成机理进行分析,发现周期条纹结构的形成与钛表面氧化层有密切的关系。 相似文献
16.
Superhydrophobic surfaces fabricated by microstructuring of stainless steel using a femtosecond laser 总被引:1,自引:0,他引:1
Fabrication of superhydrophobic surfaces induced by femtosecond laser is a research hotspot of superhydrophobic surface studies nowadays. We present a simple and easily-controlled method for fabricating stainless steel-based superhydrophobic surfaces. The method consists of microstructuring stainless steel surfaces by irradiating samples with femtosecond laser pulses and silanizing the surfaces. By low laser fluence, we fabricated typical laser-induced periodic surface structures (LIPSS) on the submicron level. The apparent contact angle (CA) on the surface is 150.3°. With laser fluence increasing, we fabricated periodic ripples and periodic cone-shaped spikes on the micron scale, both covered with LIPSS. The stainless steel-based surfaces with micro- and submicron double-scale structure have higher apparent CAs. On the surface of double-scale structure, the maximal apparent CA is 166.3° and at the same time, the sliding angle (SA) is 4.2°. 相似文献
17.
Laura Gemini Masaki Hashida Masahiro Shimizu Yasuhiro Miyasaka Shunsuke Inoue Shigeki Tokita Jiri Limpouch Tomas Mocek Shuji Sakabe 《Applied Physics A: Materials Science & Processing》2014,117(1):49-54
Laser-induced periodic surface structures (LIPSS) were formed on Si and SiC surfaces by irradiations with femtosecond laser pulses in air. Different kinds of self-organized structures appeared on Si and SiC at laser fluences slightly higher than the damage threshold, which was measured by confocal laser scanning microscope. The characteristic spatial periodicity of every observed structure was estimated reading the peak values of the 2D Fourier transform power spectra obtained from SEM images. The evolution of the spatial periodicity was finally studied with respect to both the laser fluence and the number of laser pulses. As already observed for metals, the behavior of the spatial periodicity on laser fluence can be related to the parametric decay of laser light into surface plasma waves. Our results suggest a wide applicability of the parametric decay model on different materials, making the model a useful tool in view of different applications of LIPSS. 相似文献
18.
We present periodic ripples and arrays of protrusions formed on the surface of silicon after irradiation by low-fluence linearly polarized femtosecond laser pulses. Laser-induced periodic surface structures (LIPSS) are observed for irradiation at center wavelengths of 800, ∼ 1300, and ∼ 2100 nm, with the structure periods somewhat less than the incident wavelengths in air. Additionally, we observe structures with spatial periods substantially less than the incident laser wavelengths. These sub-wavelength periodic structures form only when the photon energy is less than the silicon bandgap energy. We discuss a number of factors which may contribute to the generation of this surface morphology. 相似文献
19.
Long lines of periodic hole structures were produced on a gold film, a glass slide and polystyrene by laser ablation using interfering femtosecond lasers split by a transmission grating. An optical system comprising a cylindrical lens added to an imaging system with a transmission grating was used to obtain the interference of two beams along a long length, and high laser fluence was used to achieve laser ablation. The separation of each hole was 6.25 m, and the total length of the structure produced reached 6 mm, which is longest periodic structure produced by a shot of femtosecond laser. PACS 42.62.-b; 07.60.Ly; 42.40.Eq 相似文献
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基于Sipe-Drude模型和表面等离子体激元(SPP)的干涉理论分别对单脉冲飞秒激光诱导硅表面形成低频率周期性波纹进行分析研究.探究了波长800 nm、脉宽150 fs的单个飞秒激光烧蚀硅造成不同激发水平下波纹形貌的变化,考虑到材料的光学性质变化(由Drude模型得到的介电常数变化),引入包含双温方程的电子数密度模型.计算结果表明,Sipe-Drude和SPP理论都适用于分析和解释高激发态下周期性波纹,但Sipe-Drude理论更适合分析更为广泛的周期性波纹结构.同时,波纹延伸方向总是垂直于入射激光偏振方向,其空间周期略小于激光波长,并受到入射激光通量的影响.在激光通量为0.38 J/cm~2时,波纹周期达到最小值.另外,还得到了不同入射角度的波纹周期变化情况,并在不同偏振态下随入射角度增大时波纹周期呈现相反的变化趋势.该研究对于理解飞秒激光造成硅表面形成周期结构及其在加工硅材料领域具有重要参考意义. 相似文献