Soliton glasses in Fabry-Perot resonators

Frequency combs generated in microresonators by nonlinear states, such as soliton crystals, with crystalline defects can provide a rich optical spectrum that is useful for RF applications. In this paper, we report on the existence of a novel soliton glass solution to a modified Lugiato-Lefever equation, which we then show can be theoretically stable for Fabry-Perot microresonators. Soliton glasses are unique compared to previously reported soliton crystals and molecules in that soliton glasses produce a spectral line spacing that equals the inverse of the repetition time of the waveform in the cavity, accompanied by a stable aperiodic temporal spacing between soliton pulses in the resonator. Like a material glass, the soliton glass is characterized by short-range order and long-range disorder. We show that there are transition regions to access the soliton glass that go through spatio-temporal chaos. We computationally verify the stability of the glass over time scales equal to 2000 photon lifetimes using conventional evolutionary simulations in the presence of substantial noise. We also demonstrate the linear stability of the glass solutions by showing that any perturbations decay on a time scale that is on the order of the photon lifetime.