  We theoretically propose and investigate an optical analogue of neutrino
oscillations in a pair of vertically displaced binary waveguide arrays with
longitudinally modulated effective refractive index. Optical propagation is
modelled through coupled-mode equations, which in the continuous limit lead to
two coupled Dirac equations for fermionic particles with different mass states,
i.e. neutrinos. We demonstrate that neutrino oscillations can be quenched by
nonlinear effects, and we predict the existence of neutrino solitons.
Incidentally, these phenomena are expected to play an important role in massive
supernova stars. Our results pave the way for using binary waveguide arrays as
a classical laboratory for predicting exotic effects in particle physics and
astrophysics.
