Solutions of nonlinear-optics equations found outside the approximation of slowly varying amplitudes and phases
Belenov E. M. , Nazarkin A. V.
A class of new nonlinear effects in the interaction of an electromagnetic field with a medium has been established: the existence of "half-wave" electromagnetic-field solitons, which is induced by a field of "Josephson" currents, which effectively multiply the light frequency.