Typical textbook problems in Classical Optics require little more than high school mathematics. At varying difficulties, elementary differential equations may be required for deriving equations of optics from Maxwell's Equations.
An elementary problem in Modern Optics involves the summing of states of photons, and this can be done as a simple geometric sum or as a messy integral. The equations for diffraction and interference are thusly derived.
It also includes geometrical optics.