Thin film mediated and direct observation of LIPSS on soda-lime glass by femtosecond IR laser beam

•This paper investigates the formation of femtosecond laser-induced LIPSS on soda-lime glass substrate.•LIPSS formation on glass substrates can be induced through thin film layer for both top and bottom material irradiations.•Both HSFL and LSFL period sizes increase with higher repetition rates.•Direct LIPSS on glass substrates was successfully achieved in this study.•Heat accumulation and spectroscopy investigations were conducted to understand LIPSS formation mechanisms. In this work, we present an new approach for creating laser-induced periodic surface structures (LIPSS) on a soda-lime glass using a femtosecond (fs) laser source, marking the first instance of such a process. The formation of LIPSS upon irradiation with linearly polarized fs-laser pulses (τ = 300 fs, λ = 1030 nm) in the air environment is experimentally studied. Due to the nonlinear absorption behavior of the fs-laser beam in soda-lime glass, we conducted three different investigations to irradiate the glass substrate: (i) thin film-mediated LIPSS under top material irradiation, (ii) thin film-mediated LIPSS under bottom material irradiation, and (iii) LIPSS on glass substrate under bottom material irradiation. In the first case, High Spatial Frequency-LIPSS (HSFL) are observed, with parallel orientation to the laser beam polarization (E), across four different repetition rates or frequencies (f): 10 kHz, 50 kHz, 100 kHz, and 250 kHz. Additionally, the scan-axis alignment with the laser beam polarization significantly influences the uniformity of the generated LIPSS along the scan line. Redeposition is observed when the scan axis is parallel to the laser beam polarization, as compared to the perpendicular direction. In the second case, simultaneous formation of parallel (HSFL) and perpendicular Low Spatial FrequencyLIPSS (LSFL) to the laser beam polarization was highlighteded, exhibiting periods ranging from 200 nm to 550 nm for bottom irradiation. This observation occurs as the repetition rate varies between 10 kHz to 250 kHz. In the third case, we observed the LSFL formation without thin film layer on soda-lime glass material (bottom irradiation) when utilizing the maximum repetition rate f = 250 kHz. A notable alteration in the spatial period (545 nm - 585 nm) upon adjusting the focal distance (71 mm - 72 mm) between the substrate and the focal lens was evidenced. A possible mechanism of LIPSS formation has been discussed in the three different cases. The observation of regularly dis