| Abstract [eng] |
The rapid advancement of solid-state laser systems and the continuous increase in laser output power – the optical Moore’s law – enabled the generation of femtosecond-ultraviolet (fs-UV) pulses. Even though the efficiency of ultrashort pulse generation in the deep-UV spectral range is currently only a few percent, the output power is now sufficient to ablate high bandgap dielectric materials. While ultrashort pulses offer high temporal energy localization, short wavelengths in the UV range offer high spatial energy confinement. Therefore, fs deep-UV laser pulses have great potential for very precise surface modifications. This dissertation focuses on the fs deep-UV pulse interaction with glasses and crystals. Ablation and material removal mechanisms are explored. Remarkably, precise ablation depth control, suitable for micro-optics fabrication, is demonstrated. A substantial improvement in ablation quality with reduced photomechanical fragmentation was observed during micro-channel ablation on c-cut sapphire when using deep-UV laser pulses rather than infrared ones. Enhanced depth control and surface quality when utilizing fs deep-UV pulses were successfully demonstrated for the first time in the fabrication of diffractive optical elements. Specifically, four-phase level diffractive photon sieve formation on the surface of fused quartz, as well as binary diffractive axicon formation on the surface of barium fluoride, is demonstrated. The findings highlight promising capabilities of femtosecond deep-UV pulses in precision optics manufacturing. |
