Anderson localization of electromagnetic waves in three dimensions

Anderson localization is a halt of diffusive wave propagation in disordered systems. Despite extensive studies over the past 40 years, Anderson localization of light in three dimensions has remained elusive, leading to the question of its very existence. Recent advances have enabled finite-difference time-domain calculations to be sped up by orders of magnitude, allowing us to conduct brute-force numerical simulations of light transport in fully disordered three-dimensional systems with unprecedented dimension and refractive index difference. We show numerically three-dimensional localization of vector electromagnetic waves in random aggregates of overlapping metallic spheres, in sharp contrast to the absence of localization for dielectric spheres with a refractive index up to 10 in air. Our work opens a wide range of avenues in both fundamental research related to Anderson localization and potential applications using three-dimensional localized light. Whether Anderson localization of light can be achieved in three dimensions has remained an open question. Numerical calculations now show that it is possible with a random arrangement of metallic spheres, but not with dielectric ones.