Broadband space-time wave packets propagating 70 m

The propagation distance of a pulsed beam in free space is ultimately limited by diffraction and space-time coupling. Space-time (ST) wave packets are pulsed beams endowed with tight spatio-temporal spectral correlations that render them propagation-invariant. Here we explore the limits of the propagation distance for ST wave packets. Making use of a specially designed phase plate inscribed by gray-scale lithography and having a laser-damage threshold of similar to 0.5 J/cm(2), we synthesize a ST light sheet of width approximate to 700 mu m and bandwidth similar to 20 nm, and confirm a propagation distance of approximate to 70 m. (c) 2019 Optical Society of America