We report on a gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) able to detect multiple gas species for environmental monitoring applications, by exploiting a Vernier effect-based quantum cascade laser as the excitation source. The device emission spectrum consists of ten separated emission clusters covering the range from 2100 up to 2250 cm⁻¹. Four clusters were selected to detect the absorption features of carbon monoxide (CO), nitrous oxide (N₂O), carbon dioxide (CO₂), and water vapor (H₂O), respectively. The sensor was calibrated with certified concentrations of CO, N₂O and CO₂ in a wet nitrogen matrix. The H₂O absorption feature was used to monitor the water vapor within the gas line during the calibration. Minimum detection limits of 6 ppb, 7 ppb, and 70 ppm were achieved for CO, N₂O and CO₂, respectively, at 100 ms of integration time. As proof of concept, the QEPAS sensor was tested by continuously sampling indoor laboratory air and monitoring the analytes concentrations.

In this work, the incubation effect on the laser ablation threshold of quartz, after multi-shot irradiation with femtosecond pulses at 1030-nm-wavelength with different repetition rates, was investigated. A strong decrease of the multi-pulse ablation threshold with the number of pulses N was found due to incubation. Moreover, the influence of the repetition rate was negligible in the investigated frequency range which went from 0.06 to 200 kHz. A saturation of the threshold fluence value was observed at number of pulses N > 100 which has been found to be well fitted by an exponential incubation model. Using such model, we estimated the single-pulse ablation threshold value and the incubation coefficient for quartz, which were found equal to F_th,1 = 6.23 ± 0.23 J/cm² and k = 0.058 ± 0.004.

Carbon fibre-reinforced polymers (CFRP), thanks to their properties such as lightness, resistance to corrosion and fatigue, are emerging composite materials in the aeronautic fields, guaranteeing to reduce weight and costs by maintaining high performances in terms of strength and security. For preventing fluid damage and freezing, in aeronautic applications, CFRP parts need to be coated by painting. However, the paint/coating adhesion on CFRP composites is generally poor and affected by surface conditions. In this work, femtosecond laser texturing was investigated as an approach to improve adhesion of superhydrophobic coatings (SHC) to CFRP substrates. The laser textured surfaces show, after coating, a more lasting superhydrophobic behaviour compared to the as received sample, even after several cleaning cycles, demonstrating that the laser pre-treatment is a reliable and green method to enhance the adhesion of the SHC to the composite substrate.

This study presents the performance of a multi-gas sensor for greenhouse detection based on quartz-enhanced photoacoustic spectroscopy (QEPAS). The QEPAS sensor exploits an innovative, compact three-wavelength laser module as excitation source. The module integrates three interband cascade laser chips with a beam combining system, all enclosed in a compact metallic package with sizes of 40 × 52 × 17 mm to generate a single output beam. The multi-gas QEPAS sensor was tested in a laboratory environment for the sequential detection of two greenhouse gases, methane (CH₄) and carbon dioxide (CO₂), and a precursor greenhouse gas, carbon monoxide (CO). At an integration time of 100 ms, minimum detection limits of 21 ppb, 363 ppb, and 156 ppb, were estimated for CH₄, CO_2, and CO detection, respectively, all well below their natural abundance in air.

In this study, polymethyl methacrylate (PMMA) is joined with fused silica using pulsed femtosecond laser transmission micro‐welding. This technique enables the welding of transparent materials to each other without the need for intermediate opaque layers, through localized energy deposition. The laser parameters – peak fluence, scanning speed, and hatch distance – are systematically optimized to maximize joint shear strength. The ATR‐FTIR spectroscopic analysis has proven that mechanical interlocking is the primary mechanism of joint formation between the two materials. An analytical model based on heat accumulation is developed to describe the joining process, with a good predictive quality confirmed by comparison with the experimental results. This joining approach is applied to seal a hybrid PMMA‐fused silica microfluidic chip. The device has successfully passed a static leakage test by withstanding pressures up to the full‐scale value of the employed microfluidic pump at 2 bar, demonstrating the effectiveness of femtosecond laser transmission welding for fabricating robust and reliable joints in hybrid microfluidic devices.

In this work, femtosecond laser cutting of quartz wafers was demonstrated as an environmentally friendly alternative to the standard etching methods for production of sensitive sensor devices. The proposed approach employed milling channels for processing of the entire wafer thickness. The laser parameters examined for this procedure were the pulse energy, the number of scans and the channel width. Subsequent analysis of each channel focused on evaluating its depth, the angle of tapering, and the overall quality of the cut. The laser system operated at a central wavelength of 515 nm, delivering pulses with a temporal width of 390 femtoseconds. After identifying the optimal laser parameters for achieving the best channel quality through the wafer thickness (280 μ m), the method was used to directly laser-cut quartz microresonators in a tuning-fork geometry. The resonant performance of laser-cut tuning forks was simulated and experimentally validated using a laser-vibrometer under photoacoustic excitation. The results matched standard quartz-tuning-fork behavior, with the junction quality between the body and prongs significantly impacting performance. This study confirms femtosecond laser cutting as an efficient, eco-friendly method for producing quartz micro-devices, enabling single prototype fabrication not achievable with conventional methods.