Temporal focusing of ultrashort pulsed Bessel beams into Airy-Bessel light bullets

We present measurements of the impulse response of a circular phase diffraction grating in dependence of the field point location behind it. These measurements were carried out using a white-light spectral interferometry set-up, which employs photonic crystal fibers in both the signal and reference arms, and achieves a few micron spatial and almost one-wave-cycle temporal resolution. Our study shows that the grating as a simple and robust single-element optical device (i) suppresses the material-induced spread of ultrashort pulses, (ii) thereby generates the Airy-Bessel light bullets, and (iii) enables temporal focusing of the pulses at the prescribed propagation depth. (C) 2012 Optical Society of America