Improvement of SNR in laser-induced breakdown spectroscopy using microwave and multifiber synergy

Aiming to significantly improve the accuracy of LIBS measurements, we have achieved a significant improvement in MW injection, further SNR enhancement we demonstrate here using multi-fiber to receive the plasma spectrum. Laser-induced breakdown spectroscopy (LIBS) is often limited by weak plasma emission and poor signal-to-noise ratio (SNR), which restrict its detection limits for trace element analysis. In this study, we investigated a dual-enhancement strategy that combines a coaxial multifiber bundle with microwave (MW) excitation. A six-fiber array (200 µm core, coaxial geometry) increased plasma light collection efficiency, yielding up to a six-fold improvement in broadband emission intensity compared to a single-fiber configuration. When coupled with a 2.45 GHz pulsed microwave source, emission signals were further amplified by two to three orders of magnitude. The combined multifiber–microwave approach produced a dramatic ~ 2000-fold enhancement in emission intensity and a two- to three-order-of-magnitude improvement in SNR relative to conventional LIBS. Preliminary measurements on aluminum alloys demonstrated that the limit of detection improved from 1.016 wt.% (no MW) to 0.590 wt.% (with MW) for aluminum (Al), and from 0.378 wt.% to 0.323 wt.% for iron (Fe). The MW effect alone provided a ~ 500-fold enhancement, while fiber bundling contributed more than a 7.5-fold gain, nearly proportional to the number of fibers. Together, these improvements yielded an overall SNR increase of approximately 1500-fold compared with standard LIBS. To our knowledge, this is the first report demonstrating the synergy between multifiber collection and microwave excitation in LIBS. These findings open new opportunities for extending LIBS detection limits in applications such as environmental monitoring, alloy characterization, and nuclear materials analysis.