Beam propagation of intense ultrashort laser pulses inside transparent dielectric materials for controlled 3D micro structuring

Summary form only given. Ultrashort laser pulses (with pulse durations below 5 ps) offer the possibility for microstructuring the surface of transparent materials and inside the bulk. The interaction of ultrashort laser pulses at a wavelength of 800 nm with the bulk of transparent materials like fluorides and oxides depends strongly on the pulse duration. To obtain equal conditions for the different experiments the laser beam was focused onto the front surface of the different samples. At a low fluence below surface damage threshold it was possible to initiate damage inside the bulk and with increasing shot numbers the damage track moves towards the surface. The pulse duration was 1.1 ps, characterizing a limit at which the self-focusing driven bulk damage was observable. While at sub-ps pulses no permanent damage was registered, at 5.3 ps only 10 laser shots were necessary to introduce damage inside the bulk of BK7.