Temporal Talbot effect of optical dark pulse trains

The temporal Talbot effect describes the periodic self-imaging of an optical pulse train along dispersive propagation. This is well studied in the context of bright pulse trains, where identical or multiplied pulse trains with uniform bright waveforms can be created. However, the temporal self-imaging has remained unexplored in the dark pulse regime. Here, we disclose such a phenomenon for optical dark pulse trains, and discuss the comparison with their bright pulse counterparts. It is found that the dark pulse train also revives itself at the Talbot length. For higher-order fractional self-imaging, a mixed pattern of bright and dark pulses is observed, as a result of the interference between the Talbot pulses and the background. Such unconventional behaviors are theoretically predicted and experimentally demonstrated by using programmable spectral shaping as well as by optical fiber propagation. (C) 2022 Optica Publishing Group