Optical tuning and characterization of the anisotropic band structure of topological nodal ring systems

Abstract

We demonstrate that a topological nodal ring system driven by an off-resonant laser can be tuned between the semimetal phase and the insulator phases, including Weyl semimetal, semi-Dirac semimetal, and normal insulator phases. The controlling parameters are the disorder induced energy shift and the driving laser frequency. We further show that there exists a close correlation between the low energy spectrum and the low frequency conductivity. From the frequency dependence of conductivity components, one can deduce the anisotropic energy dispersion along different directions. This result offers a convenient optical method to tune and characterize electronic properties of nodal ring systems.