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K: Kurzzeitphysik
K 3: Laser beam - matter interaction
K 3.5: Talk
Thursday, March 20, 2003, 12:30–12:45, F04
Investigation of the Photon-Mater interaction in the femtosecond regime by time-resolved Nomarski-photography and transient absorptions spectroscopy via the pump and probe method — •Hooman Khajehnouri1, Alexander Horn1, Ernst Wolfgang Kreutz1, and Reinhart Poprawe1,2 — 1Lehrstuhl für Lasertechnik, Rheinisch-Westfälische Technische Hochschule Aachen, Steinbachstraße 15, 52074 Aachen, Germany — 2Fraunhofer Institut für Lasertechnik, Steinbachstraße 15, 52074 Aachen, Germany
The interaction of ultrashort pulsed laser radiation in the femtosecond regime with fused silica, quartz and BK7-glass with time-resolved spectroscopy and time-resolved Nomarski microscopy has been investigated.
By focusing the beam in a water jet a whitelight continuum with broad continuum (λ =300-850 nm) has been generated with a conversion efficiency of 0.92%. The whitelight continuum has been characterized by spectroscopy and cross-correlation.
The interaction of a laser pulse within different substrates has been investigated by time-resolved Nomarski-photography and transient absorptions spectroscopy via the pump and probe method. The development of shock waves and refraction index changes during and after irradiation in BK7-glass and fused silica has been compared.
An absorption band ranging from UV to IR has been registered for BK7-glass and fused silica the absoption starts 2.5 ps after excitation with a fs laser pulse with a relaxation time 4.5 ns. The absorption band changes the frequency position equal to the chirp of the whitelight continuum.