  We demonstrate low-threshold random lasing in random amplifying layered
medium via photon localization. Lasing is facilitated by resonant excitation of
localized modes at the pump laser wavelength, which are peaked deep within the
sample with greatly enhanced intensity. Emission occurs into long-lived
localized modes overlapping the localized gain region. This mechanism overcomes
a fundamental barrier to reducing lasing thresholds in diffusive random lasers,
in which multiple scattering restricts the excitation region to the proximity
of the sample surface.
