A media storage device is provided. The device comprises different
configurations of a luminescent layer comprising a luminescent material
capable of emitting light while being bombarded by a beam from a beam
transmitter, a detector for detecting the light emitted from the
luminescent layer, and a phase-change layer located proximate the
luminescent layer. The phase-change layer is able to transform from a
first phase to a second phase. Light emitted from the luminescent layer
and received by the detector materially differs when the phase-change
layer transforms from the first phase to the second phase.