Minimal observables for discriminating laser cavity solitons in a microresonator-filtered fibre laser Invited

We present a physics-guided discrimination approach for the practical identification of laser cavity solitons in a microresonator-filtered fibre laser. We introduce simple experimental observables derived from radio-frequency characterisation of the laser output, such as the low-frequency variance around DC and the normalised AC power. We show that, in conjunction with simple optical-spectrum observables such as the number of comb lines, they are sufficient to discriminate laser cavity solitons within the experimental microcomb landscape defined by the key control parameters of the system—erbium pump power and fibre-cavity length. Based on these quantities, we discuss simple heuristic figures of merit that exhibit a clear minimum for soliton states, paving the way for automated state discrimination.