Abstract

We present a femtosecond pulse self-shortening technique based on the transient regime of multiple filamentation in thin samples with Kerr nonlinearity. In this regime, a pulse passing through the sample keeps its front part unaffected by the multiple filamentation while the trailing part of the beam is broken into many filaments. The multiple filamentation in the trailing part causes strong on-axis intensity losses due to diffraction and refraction that allows far-field spatial filtering of the pulse front edge. Spectrum broadening due to self-phase modulation at the pulse front edge ensures the output bandwidth supporting truncated pulse duration. At the input intensity of $3\mathrm{TW}/{\mathrm{cm}}^2$, four- and two-fold self-shortening of 87 fs transform-limited pulses at 473 nm have been experimentally observed in a 1-mm-thick fused silica plate and 0.2-mm-thick PET film, respectively, without the use of additional dispersive elements. Results obtained in this paper show that this technique is simple and has, in principle, no limit in energy upscaling.

© 2018 Optical Society of America

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