LASER-ABLATION OF DIELECTRICS WITH PULSE DURATIONS BETWEEN 20 FS AND 3 PS

Laser-induced ablation has been extended down to a pulse duration of 2 0 fs generated by a Ti sapphire laser system at a wavelength of 780 nm . Barium aluminum borosilicate glass with an extremely high glass tran sformation temperature (similar to 600 degrees C) served as target mat erial. The most significant observation was a substantial decrease of the ablation threshold Fluence at pulse durations below 100 fs. All re sults indicate a dominant role of multiphoton absorption in addition t o collisional ionization in this time domain. (C) 1996 American Instit ute of Physics.