Double Resonance and Coherent Parametric Self-Mode-Locking in CW Superradiant Lasing

We find an intriguing regime of simultaneous emission of two power trains of superradiant pulses and soliton-like pulses in a class C laser with a low-Q combined cavity that supports two broadband superradiant modes and many quasi-monochromatic self-locked modes under the condition of double resonance when (i) the latter modes have an intermode spacing two times less than a frequency spacing between the superradiant modes and (ii) a pulse-repetition interval in an oscillogram of each superradiant mode is multiple of a pulse-repetition cycle of the self-mode-locking solitons, i.e., a cavity round-trip period.