Symmetry breaking in a T-shaped photonic waveguide coupled with two identical nonlinear cavities

We consider light transmission in a T-shaped photonic waveguide coupled with two identical symmetrically positioned nonlinear microcavities. We present two types of symmetry breaking. The first one is a result of mixing of the symmetric input wave with antisymmetric bound states in the Fabry-P\'erot interferometer architecture. Similarly, the second mechanism of the symmetry breaking is the result of mixing the symmetrical input wave with the antibonding bound state in a straight waveguide coupled with two cavities positioned perpendicular to the waveguide. In both cases the mixing is due to nonlinearity. In turn, the symmetry-breaking solutions give rise to nonsymmetrical outputs in the T-shape waveguide. These effects are directly demonstrated by the electromagnetic field solutions which are complimented by coupled mode theory for the light transmission.