Intrinsic dichroism in amorphous and crystalline solids with helical light

Abstract Amorphous solids do not exhibit long-range order due to the disordered arrangement of atoms. As a result, they lack translational and rotational symmetry on a macroscopic scale and are isotropic, meaning their physical properties remain the same in all directions. Because of their lack of symmetry, differential absorption of polarized light, called dichroism, is not known to exist in amorphous solids. However, they possess short- to medium-range order that can cause them to exhibit some features similar to crystalline solids. Using helical light beams that carry orbital angular momentum as a probe, we demonstrate that dichroism is intrinsic to both amorphous and crystalline solids. We show that in the nonlinear regime, angle-dependent absorption of helical light can map the crystal symmetry - a macroscopic feature, whereas helical dichroism is responsive to the short- to medium- range order whose existence is explained in terms of interband multiphoton-assisted tunneling. We also demonstrate that the helical dichroism signal is sensitive to chirality and its strength can be controlled and tuned using a superposition of OAM and Gaussian beams. Our research challenges the conventional knowledge that dichroism does not exist in amorphous solids and enables to manipulate the optical properties of solids, opening new opportunities for development of chiroptical spectroscopy.