Phase conjugacy and symmetries in general optical systems

Various symmetry properties related to phase conjugation are investigated, indicating some new configurations in which these symmetries may arise. Sufficient criteria required to attain those properties are derived for arbitrary optical systems, and previous work by Wolf [ J. Opt. Soc. Am.70, 1311 ( 1980)] and Montgomery [ Opt. Lett.6, 314 ( 1981)] is generalized beyond free-space propagation.