  We investigate the effect of hydrogen coverage on the optical conductivity of
single-side hydrogenated graphene from first principles calculations. To
account for different degrees of uniform hydrogen coverage we calculate the
complex optical conductivity for graphene supercells of various sizes, each
containing a single additional hydrogen atom. We use the linearized augmented
plane wave (LAPW) method, as implemented in the WIEN2k density functional
theory code, to show that the hydrogen coverage strongly influences the complex
optical conductivity and thus the optical properties, such as absorption, of
hydrogenated graphene. We find that the optical conductivity of graphene in the
infrared, visible, and ultraviolet range has different characteristic features
depending on the degree of hydrogen coverage. This opens up new possibilities
to tailor the optical properties of graphene by reversible hydrogenation, and
to determine the hydrogen coverage of hydrogenated graphene samples in the
experiment by contact-free optical absorption measurements.
