High-fluence femtosecond laser ablation of silica glass: effects of laser-induced pressure

Abstract

A pump-probe technique is employed to investigate the dynamic process of femtosecond laser ablation of silica glass, and three stress waves are observed inside the silica glass in the time-resolved shadowgraphs at a fluence of 40 J cm−2. It is believed that the first stress wave is a thermoelastic wave generated by thermal expansion, while the second and the third are generated subsequently by the mechanical expansions as a result of the extremely high pressure induced by the laser. By employing digital holography, the ablation crater is investigated to identify the ablation results, and high-density silica glass is found beneath the ablation crater, which is also the result of the laser-induced pressure. Furthermore, it is found that more stress waves will be generated at a higher fluence, and the thresholds for the generation of the first, second and third stress wave are measured to be about 2 J cm−2, 6 J cm−2 and 31 J cm−2, respectively. The theoretical calculation result shows that the laser-induced pressure increases with the increase in fluence and can be on the scale of TPa, and we believe a higher pressure will induce more mechanical expansions and therefore more stress waves.

Pure Blue Perovskites Nanocrystals in Glass: Ultrafast Laser Direct Writing and Bandgap Tuning

“…In the ultrafast laser direct writing, the laser energy is injected in volume of a few cubic micrometers, leading to a strong thermal accumulation with localized high pressure and temperature. [23][24][25] In these extreme conditions, liquid nanophase separation can be generated in asprepared glass systems due to the presence of the chemical potential gradient. [26][27][28] For the Pb/Cd glass system, firstly, the separation of the Pb-rich liquid perovskite phase from the glass matrix phase was occurred.…”

“…[17,32,33] The localized temperature and pressure induced by ultrafast laser have a diverse effect on liquid nanophase separation. The pressure generated inside the glass can reach several even dozens of gigapascal levels with different laser parameters, [23,24] which can facilitate the liquid separation processing. [26][27][28]34] To reveal the underlying mechanism for the Cd 2+ ion substitution on bandgap engineering, we performed DFT calculations for shown.…”

Formation Mechanism of Elemental Te Produced in Tellurite Glass Systems by Femtosecond Laser Irradiation

“…The pressure is estimated to be around a few TPa in the volume of the fused silica and on its surface when it is irradiated by fs‐laser with an energy density of 40 J cm −2 . [ 61 ] The generated pressure results in high‐density silica [ 62 ] and a new crystalline phase [ 63 ] in fused silica or elemental aluminum formation [ 64 ] in the sapphire (α‐Al 2 O 3 ). Additionally, the surface cracks along the laser writing direction upon fs‐laser irradiation in Figure S8 indicate the stress level exceeds Young's modulus of tellurite glass (≈42 GPa).…”

Enabling orders of magnitude sensitivity improvement for quantification of Ga in a Ce matrix with a compact Echelle spectrometer

“…However, collecting the spectra at later times reduces recorded signal intensity as the LIBS plasma is significantly cooler, which diminishes the sensitivity of a derived calibration curve. 42 Thus, there is a trade-off between the mitigation of self-absorption effects and achievable univariate calibration sensitivity when increasing the gate delay. This trend is expressed in the fitting parameters shown in Table 1 as longer gate delays yield a lower ‘ a ’ coefficient (sensitivity) while improving the ‘ b ’ coefficient (self absorption).…”