Effects of periodic structures on the. coherence properties of blackbody radiation

Radiative properties have been studied for one-dimensional dielectric multilayer structures subjected to blackbody radiation sources. The total hemispherical transmittances are calculated for periodic structures and structures with random variation in layer thickness, using wave-optics and ray-tracing methods. Simulation results show that for periodic structures, the transmittance calculated using wave optics approaches a nonzero constant value with an increasing number of layers, while the transmittance obtained using the ray-tracing method asymptotically approaches zero. For random structures, the transmittance given by wave optics drops to zero at different rates depending on the order of random variations in layer thickness. It is found that the wave interference effect always plays a role when dealing with multilayer structures. The results are explained based on extended and localized waves.