A Fundamental Understanding of the Dependence of the Laser-Induced Breakdown Spectroscopy (LIBS) Signal Strength on the Complex Focusing Dynamics of Femtosecond Laser Pulses on Either Side of the Focus

Abstract

We correlate the focusing dynamics of 50 femtosecond (fs) laser radiation as it interacts with a silicon sample to laser-induced breakdown spectroscopy (LIBS) signal strength. Presented are concentric ring-shaped variations in the electric field in the prefocus region due to lens aberrations and nonsymmetry between the prefocus and post-focus beam profile as a result of continuum generation, occurring around the focus. Experimental results show different signal trends for both atmospheric and vacuum conditions, attributed to the existence of a continuum for the former. Lens aberrations effects on the LIBS signal strength are investigated using a plano-convex spherical lens and an aspherized achromatic lens. High-resolution scanning electron micrographs of the silicon surface after ablation, along with theoretical simulations, reveal the electric field patterns near the focus. The research results contribute to fundamental understanding of the basic physics of ultrashort, femtosecond laser radiation interacting with materials.

Keywords

Femtosecond LIBS fsLIBS Laser-induced breakdown spectroscopy LIBS Continuum Interference

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References

Bowlan

Gabolde

Trebino

. “Directly Measuring the SpatioTemporal Electric Field of Focusing Ultrashort Pulses”. Opt. Express. 2007. 15(16): 10219–10230.

Bowlan

Gabolde

Coughlan

M.A.

Trebino

Levis

R.J.

. “Measuring the Spatiotemporal Electric Field of Ultrashort Pulses with High Spatial and Spectral Resolution”. J. Opt. Soc. Am. B. 2008. 25(6): A81–A92. doi:10.1364/JOSAB.25.000A81.

Rodriguez

Bourayou

Méjean

Kasparian

Salmon

Scholz

Stecklum

Eislöffel

Laux

Hatzes

A.P.

Sauerbrey

Wöste

Wolf

J.P.

. “Kilometer-Range Nonlinear Propagation of Femtosecond Laser Pulses”. Phys. Rev. E. 2004. 69(3): 036607. doi:10.1103/PhysRevE.69.036607.

Kosareva

Daigle

Panov

Wang

Hosseini

Yuan

Roy

Makarov

Chin

S.L.

. “Arrest of Self-Focusing Collapse in Femtosecond Air Filaments: Higher Order Kerr or Plasma Defocusing”. Opt. Lett. 2011. 36(7): 1035–1037.

Chin

S.L.

Hosseini

S.A.

Liu

Luo

Théberge

Aközbek

Becker

Kandidov

V.P.

Kosareva

O.G.

Schroeder

. “The Propagation of Powerful Femtosecond Laser Pulses in Optical Media: Physics, Applications, and New Challenges”. Can. J. Phys. 2005. 83(9): 863–905. doi:10.1139/p05-048.

Théberge

Liu

Luo

Chin

S.L.

. “Ultrabroadband Continuum Generated in Air (Down to 230 nm) Using Ultrashort and Intense Laser Pulses”. Appl. Phys. B. 2004. 80(2): 221–225. doi:10.1007/ s00340-004-1689-x.

Yang

Zhou

Feng

Liu

. “The Study on Supercontinuum Generation of Femtosecond Pulse Propagating in Condensed Media”. Photonics and Optoelectronic (SOPO)2010 Symposium on. IEEE. 2010. Pp. 1–4. doi:10.1109/SOPO.2010.5504266.

Rae

S.C.

Burnett

. “Detailed Simulations of Plasma-Induced Spectral Blueshifting”. Phys. Rev. A. 1992. 46(2): 1084–1090.

Park

Lee

J.-H.

Nam

C.H.

. “Laser Chirp Effect on Femtosecond Laser Filamentation Generated for Pulse Compression”. Opt. Express. 2008. 16(7): 4465–4470.

10.

Parkes

Tate

A.J.

Schumacher

. “Plasma Formation and Self-Focusing in Continuum Generation”. Ohio State University: 2003. http://www.physics.ohio-state.edu/∼reu/03reu/REU2003reports/Parkes_final.pdf [accessed Nov 18, 2013].

11.

Schiffern

Doerr

Alexander

D.R.

. “Optimization of Collinear Double-Pulse Femtosecond Laser-Induced Breakdown Spectroscopy of Silicon”. Spectrochim. Acta, Part B. 2007. 62(12): 1412–1418. doi:10.1016/j.sab.2007.10.042.

12.

Parigger

Tang

Plemmons

D.H.

Lewis

J.W.L.

. “Spherical Aberration Effects in Lens-Axicon Doublets: Theoretical Study”. Appl. Opt. 1997. 36(31): 8214–8221.

13.

Parigger

C.G.

. “Laser-Induced Breakdown in Gases: Experiments and Simulation”. In: Miziolek

A.W.

Palleschi

Schechter

, editors. Laser-Induced Breakdown Spectroscopy. Cambridge, UK: Cambridge University Press, 2006. 1st ed. Pp. 171–193. doi:10.1017/CBO9780511541261.005.