Controlling Frequency Comb Line Spacing Via Symmetry Broken Faticons

Recently, a novel temporal structure known as the faticon has been identified within ring resonators composed of Kerr materials [1]. An example of a faticon is shown in Fig. 1(a), where its unique structure is seen to depend on two interlocked field components, $\left\vert E_{ \pm}\right\vert ^2$. These components co-propagate within the ring resonator but exhibit left- and right-circular polarizations, respectively. Faticons were initially predicted through a coupled set of (normalized) Lugiato-Lefever equations and have since been experimentally observed [1]. A key mechanism enabling the existence of a faticon is the spontaneous symmetry breaking (SSB) of light [2]–[5], wherein the symmetry between the two field components' intensities $\left\vert E_{+}\right\vert ^2$ and $\vert E_{-}\vert ^{2}$ spontaneously breaks $\left(\left\vert E_{+}\right\vert ^2 \neq\left\vert E_{-}\right\vert ^2\right)$ due to an infinitesimal change in a system parameter, such as the cavity detuning θ.