Isotopic variations and Zeeman-like splitting in the spectra of nonlinear photonic meta atoms

We study photonic meta-atoms, a unique class of composite solitary wave supported in nonlinear waveguides. We establish an analogy to one-dimensional soft-core atoms, allowing us to describe the complex dynamics via concepts from atomic physics. Higher-order dispersive effects cause specific spectral resonances characteristic for the eigenspectrum of a meta-atom. We demonstrate that subtle changes in this level of spectrum cause frequency shifts of the resonances. These shifts consist of isotopic and isomeric contributions that can be distinguished in terms of a simple model. We further demonstrate a generic mechanism that causes a Zeeman-like splitting of resonance lines.