Low energy and high-speed laser-induced breakdown spectroscopy

Here, we present very low pulse energies (below 200 nJ) at very high speed (over 100 kHz) LIBS experiment by employing our recently developed 25 ps, 14W, 2.8 GHz intra-burst repetition rate Yb-doped fiber laser system. To carry out the LIBS experiments, the laser beam is directed into a Galvo scanner and focused through a 56 mm long F-theta lens onto different materials, including steel, copper, aluminum, and silicon. Our investigation of LIBS encompassed various parameters, including varying pulse energies, the number of intra-burst pulses, and burst repetition rates. For instance, with a burst repetition rate of 100 kHz with 83 ns burst width (232 intra-burst pulses), we observed the threshold pulse energy stands at approximately 26 nJ for LIBS experiment on steel. Furthermore, at about 200 nJ, it is enough to keep a high signal-to-noise ratio. To the best of our knowledge, this is the first report on LIBS experiment by GHz-range laser operating in the burst mode regime.