Loading and unloading a time cavity moving at the speed of light

We consider nonlinear-photonic cavities, flying at the speed of light, with the ability to trap photons. We demonstrate that a nonreciprocal interaction channel can serve to load and unload the cavity.

We consider a moving cavity, induced by a perturbation of the refractive index within a nonlinear waveguide, and flying with the speed of light. Conditions that enable the creation of attractive refractive-index wells, allowing to trap photons similar to a potential well in one-dimensional quantum scattering, can be realized within the propagation dynamics in waveguides with multiple zero-dispersion points. The underlying trapping mechanism is enabled by the interaction dynamics of group-velocity matched pulses with a vast frequency gap, located in separate domains of anomalous dispersion [1]. This supports the formation of incoherently coupled pulses, in which cross-phase modulation induces attractive potentials. Here, we demonstrate that by this mechanism, solitons can form moving cavities [2], which are fundamentally different from usual resting cavities [3]: trapping is described in time rather than in space, they exhibit a superior quality factor that breaks the fundamental time-bandwidth limit obeyed by usual cavities, and their specific characteristics of energy in-flow and out-flow render them nonreciprocal. We demonstrate that when a dispersive wave crosses such a cavity, phase matching resonances can be used to transfer energy to the cavity, i.e. to load the cavity. By tailoring the phase-relation of dispersive waves for successive crossing events, the cavity can be loaded and unloaded.