In situ and ex-situ physical scenario of the femtosecond laser-induced periodic surface structures

High-frequency periodic patterns driven by non-radiative fields coupled with Marangoni convection instabilities on laser-excited metal surfaces

“…Nevertheless, the existing models fail to explain the formation of regular HSFL with orientations both perpendicular and parallel to laser polarization and periods down to λ/15 on metal surfaces [22,43], as well as more complex morphologies, consisting of hierarchical periodic surface structures [19,21,22,43,59,60,[67][68][69] and quasihexagonal arrangements [36, 47, 49-53, 70, 71]. For instance, the transitions between HSFL and LSFL are contradictory discussed in the literature, where both lithographic scenarios, based on electromagnetic field enhancement between regular rectangu-lar grooves and period reduction or grating splitting [57,[72][73][74][75], and hydrodynamic scenarios based on the instability [48,59,60] were proposed. Field enhancement on subwavelength sinusoidal grating, for instance, does not result in period reduction [15].…”

Ultrafast Laser Direct-Writing of Self-Organized Microstructures in Ge-Sb-S Chalcogenide Glass

“…Interestingly, in some cases, As 2 S 3 shows low spatial periodicity (~800 nm) at lower fluence and high spatial periodicity around 200 nm at higher fluence [28][29][30]. The possible mechanism has been interpreted with the pump-probe experiment previously [28]. The other two glass systems observed are Ge-S and As-Se which show low spatial periodicity around ~750 nm [31,33].…”

“…Supplementary Table S1 summarizes the average spatial periodicity of self-organized nanostructures observed on chalcogenide glass surfaces. Interestingly, in some cases, As 2 S 3 shows low spatial periodicity (~800 nm) at lower fluence and high spatial periodicity around 200 nm at higher fluence [28][29][30]. The possible mechanism has been interpreted with the pump-probe experiment previously [28].…”

“…Self-organized nanogratings [19], crystallization [20], density modulation as well as chemical composition changes [21] due to ions migration are a few examples of reported laser-induced changes in various transparent substrates. For chalcogenide glass, our knowledge about ultrashort laser interaction with these substrates is limited to a few studies [9,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Some of the first studies highlight the nonlinear absorption of chalcogenide glass and explore the usage of laser-process thin films as a waveguide [22,23].…”

“…Some of the first studies highlight the nonlinear absorption of chalcogenide glass and explore the usage of laser-process thin films as a waveguide [22,23]. In further studies, reported facts are 1) laser fluence-dependent photoexpansion and a change in refractive index [9,[24][25][26][27], 2) surface self-organized nanostructures [28][29][30][31][32][33], 3) enhanced optical nonlinearity [34][35][36]. In addition, a few studies explored specifically the laser damage threshold in binary (As-S, As-Se) and ternary (Ge-As-S) chalcogenide glass systems [37][38][39], primarily for use in fiber-based applications.…”