Plasma emission characteristics in laser-induced breakdown spectroscopy of silicon with mid-infrared, multi-millijoule, nanosecond laser pulses from a Ho:YLF excitation source

• Published in: Applied optics. Optical technology and biomedical optics Vol. 58; no. 17; p. 4592
• Main Authors: Kupfer, Rotem, Quevedo, Hernan J, Smith, Herbie L, Ha, Thanh N, Yandow, Andrew, Tiwari, Ganesh, Richmond, C Grant, Fang, Li, Manuel Hegelich, B
• Format: Journal Article
• Language: English
• Published: United States 10.06.2019
• ISSN: 2155-3165
• DOI: 10.1364/AO.58.004592

We characterized the plasma emission produced by the interaction of multi-millijoule, 40 ns duration, mid-infrared laser pulses with a silicon surface. The laser pulses were produced by a Q-switched Ho:YLF master oscillator power amplifier system. Using spectral measurements and a framing camera, we observed a spatial separation of the plasma plume, increased emission signal with low white-light generation, and a drop in the time- and space-averaged apparent plasma density with increasing pump energy. Our results can be explained by continuous heating of the plasma by the pump pulse due to the more efficient inverse bremsstrahlung absorption at longer wavelengths.