Dependence of lasing spectrum and self-mode-locking on a width of the photonic bandgap in a class C heterolaser with distributed feedback of waves in a Fabry-Perot cavity

Based on the numerical solution to the nonlinear Maxwell–Bloch equations, the joint implementation of active (parametric) and passive (coherent) mode locking for a class C heterolaser with a low-Q combined Fabry-Perot cavity in the presence of an effective distributed feedback of counter-propagating waves is demonstrated. It is shown that the multiplicity of the spectral width of the photonic band gap of the cavity to the intermode spacing far from this zone contributes to the effective phasing of quasi-monochromatic quasi-equidistant modes, thus making it possible a phenomenon of parametric coherent self-mode-locking. A number of examples are used to demonstrate typical properties of a quasi-periodic sequence of soliton-like pulses generated in the found regime, which does not require external modulation of the pump or laser parameters, or the placement of a fast-saturating absorber in it.