Limits of group-velocity tunability in dispersive media

Establish the limits on group-velocity tunability produced by non-differentiable angular dispersion for space-time wave packets propagating in dispersive media and other dispersive platforms.

Background

The paper explains that space-time wave packets can be generalized from free-space propagation to dispersive media, where their group velocity remains tunable and several related phenomena have been predicted and observed. However, the bounds governing this tunability in dispersive media have not been determined. The same unresolved issue extends to dispersive platforms such as space-time surface plasmon polaritons at metal–dielectric interfaces.

References

The limits on group-velocity tunability via non-differentiable AD in dispersive media have not yet been established .

— Limits on the free-space group velocity of optical wave packets incorporating angular dispersion. Part~II, non-differentiable angular dispersion: tutorial  (2609.19580 - Hall et al., 17 Sep 2026) in Section 8.4, “Further extensions”