Studies On The Interaction Of Ultra-short Laser With Transparent Medium

The interactions of ultra-short lasers with transparent medium and femtosecond micromachining have been intensively studied with the rapid advances in laser technology, especially the chirper pulse amplification technique. In this dissertation, laser-induced damages mechanism in the transparent medium was systematically studied by femtosecond and picosecond laser. The main are as the following:1) We investigated the optical micrograph of laser-induced damage spots on the surface of the fused silica irradiated by femtosecond and picosecond laser pulses at different intensites, respectively. These results showed that femtosecond laser pulses was better than picosecond laser pulses for micro-machining, and highly reproducible microchannels in the fused silica could be built with the diameter of about 33um and the length of 22~254um with Tr.sapphire femtosecond laser, and it was found that the damage diameter, depth and volume increased with the laser intensity increasing.2) The absorption, fluorescence and XRD spectra of Ti: Sapphire were measured and analyzed, and the optical damage of Ti:saphire by femtosecond and picosecond laser pulses were investigated, respectively. It was found the surface and the stress in the crystal had effects on the damage morphology, and the damage mechanisms including the bulk damage and the surface damage, was discussed and analyzed.