Bochum 2015 – scientific programme

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K: Fachverband Kurzzeitphysik

K 4: Lasersysteme und deren Anwendungen II

K 4.7: Talk

Tuesday, March 3, 2015, 16:00–16:20, HZO 40

Real-Time Observation of Transient Electron Density in High Band Gap Materials Irradiated with Tailored Femtosecond Laser Pulses — •Cristian Sarpe, Thomas Winkler, Jens Köhler, Nikolai Jelzow, Nadine Götte, Bastian Zielinski, Arne Senftleben, and Thomas Baumert — University of Kassel, Institute of Physics and CINSaT, D-34132 Kassel, Germany

The first step in laser ablation of high bandgap materials is the generation of a high density free electron plasma. We have shown that tailored ultrashort laser pulses are suitable for robust manipulation of optical breakdown. By using these pulses the precision of femtosecond-laser machining results in microstructures one magnitude order below the optical diffraction limit [1, 2, 3]. Here we present our studies to investigate the early-time dynamics of a free electron plasma created by shaped femtosecond laser pulses in water, as a prototype for high bandgap materials, by using a robust spectral interference technique with an enlarged temporal measurement window [4]. The phase shift between a reference and a probe pulse produced in a common-path interferometer gives accurate information about the density of the free electron plasma. The temporal evolution of the plasma is accurately observed and its dependence on the laser intensity and temporal pulse shapes is analyzed. [1] L. Englert et al., Opt. Expr. 15, 17855 (2007) [2] L. Englert et al. JLA 24, 042002 (2012) [3] M. Wollenhaupt et al., JLMN (2009) 4 (3) 144-151 [4] C. Sarpe et al., NJP 14, 075021 (2012)