Dynamic microcavities and time-dependent media in collisions of unipolar attosecond pulses of different shapes

Optics of time-varying media has been actively developing in recent decades due to new possibilities for controlling the properties of light in space and time using such media. The advent of extremely short light pulses, up to unipolar half-cycle pulses, opens up new possibilities for ultrafast control of the properties of a medium in space and time on times of the order of half the field period, which are inaccessible for conventional multi-cycle pulses. In this paper, we numerically study the dynamics of Bragg microresonators in a three-level medium whose properties vary in space and time. This occurs when unipolar light pulses of different time shapes, Gaussian and rectangular, collide in it, having a small amplitude at which the medium is slightly excited and does not return back to the ground state after the passage of the pulses. We discuss broader possibilities for controlling the properties of a medium in space and time by using half-cycle pulses of different time shapes as a result of symmetric and asymmetric collisions of pulses in the medium.