- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Submicron bubbles/voids formation in the subsurface region of soda-lime glass by single pulse fs laser-induced spallation
摘要： The formation of bubbles near the surface of soda-lime glass induced by single pulse irradiation with Ti: Sapphire laser of a wavelength of 775 nm and 150 fs pulse duration below the laser ablation threshold is reported. The bubbles with a diameter of 0.3 to 3 μm are much smaller than the spot size of ~12 μm and exhibit a semi-spherical surface, an ellipsoidal void and an upper shell thickness of approx. 100 nm. The bubbles are formed in a narrow energy range between bulk glass modification and glass ablation. The bubbles formation is accomplished with some changes of the glass morphology around the bubbles. Damaged bubbles occur near the upper laser energy limit for bubbles formation that show nanoholes or slits in the bubbles shell and opened shells exposing the bottom of the void. It is suggested, that the bubble forming mechanism is related to nonlinear processes of laser photon absorption, laser-induced spallation processes, materials heating after electron relaxation, and thermal driven, viscoplastic-mechanical processes. Mainly the material composition gradient of the soda-lime glass near the surface that affects photon absorption, melting, ablation and material expansion processes enable the formation of these bubbles. The void inside the bubble is formed first by pre-spallation resulting in a detached layer that is lifted further forming the bubbles shell by subsurface laser ablation/evaporation processes of the bulk glass. The upper shell of the bubble is formed by a thermally stable crust of corroded soda-lime glass. The results may have valuable impact to laser ablation processes for high precision fabrication. Further, the fast fabrication of such 3D submicron structures due to the single pulse interaction with the glass enables new technical processes for potential applications in sensing, photonic or microfluidic.
关键词： soda-lime glass,surface modification,single pulse,nonlinear absorption,femtosecond laser,bubble,spallation
更新于2025-09-19 17:13:59
-
Ultrafast pump-probe ellipsometry and microscopy reveal the surface dynamics of femtosecond laser ablation of aluminium and stainless steel
摘要： An ultra-short laser pulse irradiated surface passes through a sequence of physical processes that occur over a wide temporal range, from femtoseconds to microseconds. In this paper for the first time, the complete laser ablation process for industrially relevant metals, aluminium (Al) and stainless steel (AISI 304) is tracked from the initial pulse impact to the final state. Time-resolved surface analytical techniques provide a complementary description of the surface dynamics. The pump-probe ellipsometry reveals changes of the complex refractive index for the first tens of picoseconds and time-resolved microscopy of the irradiated surface gives access to changes of the relative reflectivity from the initial femtosecond pulse impact to the final state at 10 μs. The changes in optical indices are affected by an ultrafast decrease in the density of the surface within the pressure unloading process in the first picoseconds and reveal spallation as the dominant mechanism for laser ablation in Al and stainless steel. The study also implies that the ablation volume is kept at an optimum when the ablation is initiated with ultrafast pulses within the pressure unloading process and is able to evolve over eight orders of magnitude without external perturbations.
关键词： Time-resolved ellipsometry,Spallation,Laser ablation,Nanostructure,Pump-probe reflectometry
更新于2025-09-19 17:13:59