Effect of nonlinearity in the pass-through optics on femtosecond laser   filament in air
  An influence of pass-through optics on femtosecond laser pulse filamentation in ambient air is analyzed for the first time both experimentally and numerically. Propagation of high-power femtosecond laser pulse through solid optical elements introduces spatiotemporal phase modulation due to the Kerr effect. This modulation may have a strong ef-fect on the pulse filamentation in air. We demonstrated that the phase modulation obtained in the thin pass-through dielectric plate reduces the distance to the filament onset and increases the plasma channel length 
Alexander A. Dergachev, Andrey A. Ionin, Valery P. Kandidov, Daria V.   Mokrousova, Leonid V. Seleznev, Dmitry V. Sinitsyn, ...
physics.optics