Measurements of self-guiding of ultrashort laser pulses over long distances

Abstract

We report on the evaluation of the performance of self-guiding over extended distances with f /20 and f /40 focussing geometries. Guiding over 39 mm or more than 100 Rayleigh ranges was observed with the f /20 optic at ne = 1.5 × 1018 cm−3 . Analysis of guiding performance found that the extent of the exiting laser spatial mode closely followed the matched spot size predicted by 3D non-linear theory. Self-guiding with an f /40 optic was also characterised, with guided modes observed for a plasma length of 90 mm and a plasma density of ne = 9.5 × 1017 cm−3 . This corresponds to self-guided propagation over 53 Rayleigh ranges and is similar to distances obtained with discharge plasma channel guiding