Femtosecond UV Laser Pulses Research Articles

Ablation of Si and Ge Using UV Femtosecond Laser Pulses

ABSTRACTLaser ablation of silicon and germanium was carried out in moderate vacuum with l00fs to 400fs pulses at 248nm and intensities up to 3x1013 W/cm2. Evidence for non-thermal material removal was found. Imaged multishot ablation patterns display the intensity dependent self-structuring effect, forming well-known columnar structures. It is shown that continued irradiation of these structures eventually results in comparatively clean ablation. An increase of ablation rate with depth was observed. The reason is an intensity enhancement inside the pits by reflective focussing to a level where bond-breaking takes place. Furthermore, it was noticed that ablation contours can be significantly improved by electrically grounding the target.

Single-shot measurement of the intensity and phase of a femtosecond UV laser pulse with frequency-resolved optical gating

We extend to the ultraviolet frequency-resolved optical gating a new method for measuring the intensity and phase evolution of an individual ultrashort pulse without assumption. Using frequency-resolved optical gating, we measure a 310-fs, 308-nm pulse, whose phase is approximately cubic in time. We show that this phase distortion probably results from self-phase modulation and amplifier detuning.

Resonant photoionization of sputtered organic molecules by femtosecond UV laser pulses

Resonant photoionization of sputtered organic molecules by femtosecond UV laser pulses