Canceling and Inverting Normal and Anomalous Group‐Velocity Dispersion Using Space‐Time Wave Packets
Layton A. Hall, Ayman F. Abouraddy
Abstract
Abstract Angular dispersion can counterbalance normal group‐velocity dispersion (GVD) that increases the wave‐vector length in a dispersive medium. By tilting the wave vector, angular dispersion reduces the axial wave number in this case to match the pre‐GVD value. By the same token, however, angular dispersion fails to counterbalance anomalous GVD, which in contrast reduces the wave‐vector length. Consequently, GVD‐cancellation via angular dispersion has not been demonstrated to date in the anomalous dispersion regime. Here, structed femtosecond pulsed beams, known as ‘space‐time’ wave packets, are designed to realize dispersion‐cancellation symmetrically in either the normal‐ or anomalous‐GVD regimes by virtue of non‐differentiable angular dispersion inculcated into the pulsed field. Furthermore, GVD‐inversion is also verified by reversing the GVD sign experienced by the field with respect to that dictated by the chromatic dispersion of the medium itself.