Nonlinear Fano-Feshbach resonances

Symmetry breaking in binary chains with nonlinear sites

We consider a system of two or four nonlinear sites coupled with binary chain waveguides. When a monochromatic wave is injected into the first (symmetric) propagation channel, the presence of cubic nonlinearity can lead to symmetry breaking, giving rise to emission of antisymmetric wave into the second (antisymmetric) propagation channel of the waveguides. We found that in the case of nonlinear plaquette, there is a domain in the parameter space where neither symmetry-preserving nor symmetry-breaking stable stationary solutions exit. As a result, injection of a monochromatic symmetric wave gives rise to emission of nonsymmetric satellite waves with energies differing from the energy of the incident wave. Thus, the response exhibits nonmonochromatic behavior.

Switching through symmetry breaking for transmission in a T-shaped photonic waveguide coupled with two identical nonlinear micro-cavities

Using coupled mode theory we consider transmission in a T-shaped waveguide coupled with two identical symmetrically positioned nonlinear micro-cavities with mirror symmetry. For input power injected into the central waveguide we show the existence of a symmetry breaking solution which is a result of mixing of the symmetrical input wave with an antisymmetric standing wave in the Fabry-Pérot interferometer. With growth of the input power, a feature in the form of loops arises in the solution which originates from bistability in the transmission in the output left/right waveguide coupled with the first/second nonlinear cavity. The domains of stability of the solution are found. The breaking of mirror symmetry gives rise to nonsymmetrical left and right outputs. We demonstrate that this phenomenon can be explored for all-optical switching of light transmission from the left output waveguide to the right one by application of input pulses.

Light induced Josephson like current between two coupled nonlinear cavities coupled with a symmetrically positioned photonic crystal waveguide

We consider light transmission in a photonic crystal waveguide coupled with two identical nonlinear cavities positioned symmetrically beside the waveguide and coupled with each other. Using Green function theory we show three scenarios for the transmission. The first one inherits the linear case in which the light transmission preserves the symmetry. In the second scenario the symmetry is broken by the light intensities at the cavities. In the third scenario the intensities are equal but the phases of the complex amplitudes are different at the cavities. This results in a Josephson like current between the cavities. The model consideration agrees well with computations of the Poynting current in a photonic crystal waveguide coupled with two optical cavities filled with a Kerr material.

The Fano resonance in plasmonic nanostructures and metamaterials

Since its discovery, the asymmetric Fano resonance has been a characteristic feature of interacting quantum systems. The shape of this resonance is distinctively different from that of conventional symmetric resonance curves. Recently, the Fano resonance has been found in plasmonic nanoparticles, photonic crystals, and electromagnetic metamaterials. The steep dispersion of the Fano resonance profile promises applications in sensors, lasing, switching, and nonlinear and slow-light devices.