Demonstration of the space-time Talbot effect

We introduce a new effect that we call the ‘space-time’ (ST) Talbot effect in which an optical field lattice that is periodic in both space and time undergoes periodic axial revivals after propagation in free space. Although the purely spatial and purely Talbot effects have been observed separately in optics, they have not been realized simultaneously due to the disparity between the spatial and temporal Talbot lengths. Indeed, the temporal Talbot effect has been observed to date in only single-mode fibers. By identifying a new pulsed beam configuration that we call a V-wave whose diffraction and dispersion lengths are intrinsically equal, we obtain a periodic spatio-temporal lattice by discretizing the spatio-temporal spectrum of a V-wave, and consequently observe the first example of self-imaging in space and time using an optical field.