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ToF-SIMS is a sensitive technique for interrogating chemical composition at or near the surface of a material, with an emphasis on detecting elements present in extremely low quantities. Here, it was utilized to determine changes in element distribution at a muscovite surface caused by a single 150 fs laser pulse at 800 nm. Muscovite is a mineral with the standard chemical formula KAl2 (Si3Al) O10(OH)2. As a natural mineral, the composition varies. Several ions were studied including aluminium (Al), potassium (K), sodium (Na), and silicon (Si). The laser-irradiated surface area is microscopic - a few microns in diameter. To achieve spatial resolution of the ions within the laser treated region, a ∼100 nm wide ion beam is used. The laser material interaction produces a non-flat surface morphology that changes as the laser pulse fluence increases. Thus, ToF-SIMS is influenced by the ion beam shadowing effect. After the implications of artefacts linked to this are taken into account, there is a finding of net enrichment of sodium and potassium due to the laser irradiation. ToF-SIMS also shows differences in the elemental makeup of nanoparticulates ejected from the laser treated region and redeposited on the surrounding surface. With careful consideration of surface morphological changes, this study shows that ToF-SIMS can be employed in laser materials processing studies to investigate changes in elemental distribution.

Ultrafast laser pulse processing is an important tool used to modify the structural and morphological properties of a target material. Muscovite, a naturally occurring nano-layered mineral, is a material that has exhibited a complex systematic variation in the topography of laser processed sites as a function of the fluence of a single 150 fs, 800 nm laser pulse. These sites include depressed craters; raised bumps; bumps in craters, both with and without rims; and ultimately the onset of what would be identified as standard ablation. A means of quantifying the sequence of observed topographies of these micron sized modifications; which have height features ranging from a few, to a few hundred, nanometers; is required. We present the quantification of the sub-cubic-micrometer laser-modified-volumes in muscovite using full 3-D profiles obtained from optical surface profilometry. This includes quantifying modification volumes above and below the original surface plane separately. This gives information about redistribution of material. The net volume change indicates whether there is a net or apparent volume increase due to rarefraction, delamination, or cavitation, or a net volume removal. Thus, the volumetric analysis in combination with the morphological knowledge of the modified sites emerges as a potential indicator of the likely physical phenomena at play. This is illustrated by the volumetric analysis reported here-in for muscovite, exposed to single pulses in the fluence range 1.5–7 J/cm2. The OSP technique is commonly used to characterize surface roughness, and, morphology of processed surfaces, including laser processed surfaces. But, to our knowledge, this is the first time a detailed micro-volume analysis has been reported in a laser processing context. This can be applied universally to different laser processed materials, especially when multiple physical processes are at play. The resolution of the measurements is limited by the lateral and vertical resolution specifications of the OSP instrument.

Muscovite, a nanolayered transparent crystalline dielectric, is shown to respond like a polymer upon irradiation with a single 190 fs duration laser pulse, at a wavelength of 515 nm, for a range of fluences (1.4–6.4 J/cm2). Laser-pulse-modified sites were characterized using field emission scanning electron microscopy (FESEM). Cavitation and bubbling are observed in the laser processed region similar to previous observations in poly-methyl-methacrylate (PMMA). The diameter of these sites is consistent with the standard model commonly applied in laser ablation studies. These polymer-like results at 515 nm are in contrast to the response of muscovite exposed to a 150-fs single laser pulse at 800 nm for a similar range of fluences. Where a diverse range of topologies was observed as the fluence was increased. Additionally, we also report an absorption band edge at ~4 eV (for the muscovite sheet used in the study). This is lower than the previously reported band gap energy value of 7.8 eV. We propose that the differences observed at the two wavelengths are primarily due to either 2 or 3 photons being required for nonlinear photoionization and the impact of the mineral water content of muscovite (4.7 wt%).

Current active Q-switching is mainly generated by acousto-optical modulators (AOMs) or electro-optical modulators (EOMs). However, EOMs make the setup bulky, while AOMs require the radiofrequency (RF) signal and water-cooling. We present a novel approach to active Q-switching of an integrated waveguide chip laser by utilizing a deformed helix ferroelectric liquid crystal cell (6mm × 6mm) with a thickness of 2 mm. This device can be directly integrated onto the Ytterbium-doped waveguide chip and controlled by the electrical signal. In experiments, with an electrical signal with a pulse duration of 2 μs and a magnitude from 10 V to 84 V, the Q-switched lasers can be observed at a repetition rate ranging from 0.1 kHz to 20 kHz. The shortest pulse duration and the maximum slope efficiency is 38 ns and 22% respectively. This novel integrated and low-cost laser source is a promising tool for a broad range of applications such as gas sensing and LIDAR.