An event cloaking scheme that requires a single dispersive medium (instead of two successive media with opposite dispersion) has also been proposed based on accelerating wavepackets. The idea is based on modulating a part of a monochromatic light wave with a discontinuous nonlinear frequency chirp so that two opposite accelerating caustics are created in space–time as the different frequency components propagate at different group velocities in the dispersive medium. Due to the structure of the frequency chirp, the expansion and contraction of the time gap happen continuously in the same medium thus creating a biconvex time gap that conceals the enclosed events.