Sub-cycle switching at optical frequencies

Demonstrate temporally abrupt, sub-optical-cycle changes in the dielectric permittivity at optical frequencies in a photonic medium to realize time interfaces comparable to those previously achieved at microwave frequencies using metamaterials.

Background

Photonic collisions at time interfaces have been experimentally demonstrated at microwave frequencies by implementing temporally abrupt (sub-cycle) changes in a metamaterial’s dielectric properties. Achieving analogous sub-cycle switching at optical frequencies would enable direct optical implementations of these time-interface phenomena.

In this work, the authors realize coherent control using periodic (not sub-cycle) modulation in indium tin oxide at optical frequencies. They explicitly note that truly sub-cycle switching at optical frequencies has not yet been achieved, highlighting a concrete technological and experimental gap.