Ultraviolet-visible conical emission by multiple laser filaments

Conical emission from laser filaments and higher-order Kerr effect in air.

We numerically investigate the conical emission (CE) from ultrashort laser filaments, both considering and disregarding the higher-order Kerr effect (HOKE). While the consideration of HOKE has almost no influence on the predicted CE from collimated beams, differences arise for tightly focused beams. This difference is attributed to the different relative contributions of the nonlinear focus and...

HV discharge acceleration by sequences of UV laser filaments with visible and near-infrared pulses

We investigate the triggering and guiding ofDChigh-voltage discharges over a distance of 37 cmby filaments produced by ultraviolet (266 nm) laser pulses of 200 ps duration. The latter reduce the breakdown electric field by half and allow up to 80%discharge probability in an electric field of 920 kVm. This high efficiency is not further increased by adding nanosecond pulses in the Joule range at...

Visible laser emission of Pr3+ in various hosts

We report on the first observation of low temperature pulsed blue and orange laser emissions in P~~+:YAG. Furthermore, we compare these results with similar observations in YLiF4 and YAlO3 doped crystals. Pulsed laser oscillations were obtained in crystals with uncoated surfaces by direct excitation of one of the relevant Stark components of the PO, 3 ~ 1 or 3 ~ 2 states. A careful1 spectroscop...

European Ultraviolet-visible Observatory

Conical emission due to four-wave mixing enhanced by the ac Stark effect in self-trapped filaments of light.

Experimental evidence is presented that shows that the conical emission often found surrounding a near-resonant laser beam after it passes through an atomic vapor is due to nondegenerate four-wave mixing enhanced by the ac Stark effect. We demonstrate self-trapping of a pulsed dye-laser beam in sodium vapor for wavelengths 0.04 to 10 A shorter than that of the D(2) resonance and show that the f...