Veiled Talbot Effect

A freely propagating optical field having a periodic transverse spatial profile undergoes periodic axial revivals-a well-known phenomenon known as the Talbot effect or self-imaging. We show here that introducing tight spatiotemporal spectral correlations into an ultrafast pulsed optical field with a periodic transverse spatial profile eliminates all axial dynamics in physical space, while revealing a novel veiled Talbot effect that can be observed only when carrying out time-resolved measurements. Indeed, time diffraction is observed, whereupon the temporal profile of the field envelope at a fixed axial plane corresponds to a segment of the spatial propagation profile of a monochromatic field sharing the initial spatial profile and observed at the same axial plane. Time averaging, which is intrinsic to observing the intensity, altogether veils this effect.