Femtosecond laser production of metal surfaces having unique surface structures that are broadband absorbers

Abstract

Femtosecond laser induced modification of surface structure and the optical properties of metals are studied. A Ti:sapphire femtosecond laser is used for ablating bulk aluminum 2024 T3 alloy and highly pure neutron activation quality gold metal samples at different laser irradiation parameters. The ablation parameters are optimized for the two metals to form a low reflection surface in the wavelength range of 0.3–50 μm. “Black aluminum” and “black gold” metal surfaces are formed upon laser ablation, having a unique surface structure with micro- and nanosized features. Sample analysis is performed by several characterization techniques like scanning electron microscope, energy dispersive x ray, profilometry, and integrating sphere reflectance measurements. Correlation is drawn between the laser ablation parameters and the formed surface structure and its properties. The reflection of light is found to depend primarily on the surface structure (roughness) of the highly modified metal surfaces.

Self assembled nanoparticle aggregates from line focused femtosecond laser ablation

“…Most of the research on femtosecond laser material surface modification has been conducted using a spherical lens to focus the beam to a spot. A number of pulses are then illuminated on the same spot (e.g., drilling) or the sample is moved so that the laser pulses are rastered across the sample for surface modification and machining [1][2][3][4]. Using a cylindrical lens to form a line focused beam to ablate surfaces with a femtosecond laser however, is not as well documented in the literature and is the subject of this paper.…”

Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining

“…However, some authors use Equation (7) to calculate the "flat-top equivalent" fluence of a Gaussian beam and report it as fluence values [77,78], whereas others use Equation (1) to report peak fluence values [5,58,[79][80][81], while describing the micromachining parameters. The fluence calculated from Equation (7) for a Gaussian beam should be reported as "flat-top equivalent" fluence.…”

“…Figure 1. Timeline of fs laser micro/nano structuring and other related works [5,[22][23][24][25][26][27][28][29][30].…”

“…Laser textured surfaces exhibiting structural color can act as a permanent paint and might be used for decorative purposes [1,2]. Highly absorptive textured surfaces can find applications in solar cells [3,4] and in stealth technology [5]. Superhydrophobic surfaces fabricated by laser texturing have many applications that include anti-icing, anti-corrosion, self-cleaning, and drag reduction [6][7][8].…”

Nanostruktúrák lézeres kialakítása különböző fémek, illetve dielektrikumok felületén

“…Ezen vizsgálatok kimutatták, hogy a lézerrel kezelt felület optikai tulajdonságai a lézeres besugárzás hatására jelentősen megváltoznak [45][46][47]. Spektroszkópiai mérések igazolták, hogy megfelelő kísérleti körülmények mellett az eredetileg magas reflexiójú anyagok közel teljesen elnyelővé tehetők, amely jelenség széles spektrális tartományon (a közeli ultraibolyától a közeli infravörösig) bekövetkezik [48][49][50]. Az abszorpciónövekedést fémek széles skálája (például platina, volfrám, arany, alumínium, acél vagy titán-ötvözetek) esetén megfigyelték [51][52][53].…”