nikitabu

It depends on the application. FEM software like COMSOL and CST Studio is typically used for simulating individual antennas. FDTD software like Lumerical is more popular for simulating metamaterials, which are basically large periodic arrays of sub-wavelength antennas.

MEEP is typically used in the nanophotonics community for simulating things metamaterials, photonic crystals, and waveguides. All of which can be thought of as optical antennas.