Random stack of resonant dielectric layers as a laser system.

We propose a random stack of resonant dielectric layers as a system for random-laser study. Owing to the Fabry-Perot resonance of the dielectric layers, the propagation of light in such systems is frequency dependent (a band structure). As a consequence, if the system is designed such that pump light is in passband while optical gain is in stop band, the laser threshold can be reduced dramatically compared with those of completely disordered systems.