Vectorial Kerr Solitons: 2D Symmetry Breaking Phenomena

Kerr cavity solitons—the time-domain counterparts of Kerr frequency combs—have driven advances from chip-scale optical clocks to low-noise microwave generation. While most studies focus on single-mode resonators, multimode vectorial systems enable richer dynamics. We report two-dimensional spontaneous symmetry breaking in vectorial cavity solitons supported by orthogonal polarization modes. Under symmetric pulsed pumping, the solitons exhibit mirror-asymmetric polarization intensities and symmetry-broken temporal positions through cascading pitchfork bifurcations. Polarization- and temporal-symmetry breaking arise independently, with the latter explained by a vectorial perturbation model. These results reveal new dynamical degrees of freedom in Kerr resonators and broaden control of vectorial states of light.