Focusing limits of intense ultrafast laser pulses in a high pressure gas: road to new spectroscopic source

Simultaneous detection and identification of multigas pollutants using filament-induced nonlinear spectroscopy

“…This is consistent with previous observations in air. 9 Analysis of the spectra in Fig. 1 shows that, besides the emission coming from N 2 + ͑B 2 ͚ u + → X 2 ͚ g + ͒ and N 2 ͑C 3 ⌸ u → B 3 ⌸ g ͒ produced by the nitrogen molecule in air, 9 some small molecular fragments, originating from the interaction of the trace species with the femtosecond laser pulses, can be observed.…”

Surface profile of material ablated with high-power lasers in ambient air medium

“…19 This observation stimulated interest in the studies of the ultra-intense laser pulse propagation in transparent media to exploit the phenomenon for laser fabrication. [20][21][22][23][24] Present results indicate that the experimental parameters can be adjusted to balance the two effects, yielding a cleaner surface profile. For more strongly focused beams, the distortion caused by the plasma was found to be significant.…”

“…19 Studies aimed at generating short columns of plasma in converging beams used for laser machining have been conducted recently. [20][21][22][23][24] The existence of a region in a beam with a relatively undistorted profile can be exploited to fabricate cleaner surfaces. Present results indicate that a desirable beam profile can be created at intensities close to the threshold.…”

Nitrogen fluorescence induced by the femtosecond intense laser pulses in air

“…It can be clearly seen from the figure that with the increase of the initial energy of the laser pulse E in , the onset of filaments moves towards the focus of the lens and the fluorescence intensity increases significantly. In addition, the filament length also [23][24][25][26] . In the transitions v-v , v and v denote the vibrational levels of upper and lower electronic states, respectively.…”