Investigations on the modification of PMMA by ultrafast laser radiation from the UV to the mid-IR spectral range

Laser-processing of organics is of increasing interest for organic electronics, e.g. the isolation process of solar cells in organic photo voltaic modules. The ablation of PMMA by single pulsed ultrafast laser radiation is investigated in the spectral range from UV (260 nm) to the mid-IR (3.8 µm) in order to determine dependencies of the ablation process on the wavelength, and the pulse energy. At ultrafast pulse durations τH < 100 fs linear absorption (photo-excitation or resonant-infrared absorption) and non-linear absorption (multi-photon absorption or tunnel ionization) represent the main processes. The excited PMMA features similar dynamics of the absorption up to delay times of 120 ps for all investigated wavelengths, determining the electronic excitation after irradiation as the dominant process.