  We study the polarization dependence of optical absorption for the modified
Haldane model, which exhibits antichiral edge modes in presence of sample
boundaries and has been argued to be realizable in transition metal
dichalcogenides or Weyl semimetals. A rich optical phase diagram is unveiled,
in which the correlations between perfect circular dichroism, pseudospin and
valley polarization can be tuned independently upon varying the Fermi energy.
Importantly, perfect circular dichroism and valley polarization are achieved
simultaneously. This unprecedented combination of optical properties suggests
some interesting novel photonic device functionality (e.g. light polarizer)
which could be combined with valleytronics applications (e.g. generation of
valley currents).
