Strong spectrospatial correlations in Anderson-localized lasing in periodic-on-average random systems

We experimentally address emergent spectrospatial correlations in a one-dimensional amplifying system that sustains Anderson-localized lasing modes. The structure is based on a periodic-on-average random template, and hence follows the frequency behavior determined by passbands and band gaps of a photonic crystal. A spectrospatial correlation map constructed for weak disorder reveals strong correlations and anticorrelations that extend over multiple band gaps. The origin of the correlation is traced to two parameters, namely the probability of generation of modes, and the congruence in the mode profiles of corresponding modes. Specific locations on the correlation map are identified that reflect the relative contribution of the two parameters. The experimental setup with a fine control on disorder strength allowed us to capture the systematic evolution of the correlation map with disorder, which uncovers an interesting variation in spectrospatial correlations in such Anderson-localized lasing systems.