Optical reflectivity and spatial mode localization of white-noise random dielectric oxide multilayers

The investigation of propagating electromagnetic waves along the random dielectric multilayers following a white-noise-like pattern is presented. The system constituents are chosen to be SiO2 and TiO2 in such a way that absence of absorption losses is guaranteed in the electromagnetic region of interest. The results of the calculation show that the reflectance of the noise-like structures depends on both the noise amplitude and the seed of the configurations; the latter being associated to the degree of randomness presented in the heterostructures, which is analyzed via specific statistical tools. Under an adequate design of the random structures it is possible to obtain broad range omnidirectionality, which is noticeably higher than the typical from periodic Bragg mirrors. In addition, selective spatial localization in the central part of the heterostructures is determined for certain propagating modes, with relative confined electric field amplitudes shown to reach up to 104 in some cases. According to the results of the simulations, this kind of heterostructures could have potential applications in photonics and optoelectronics such as solar concentrators and random lasers.