Theory of soliton stability in asynchronous modelocking

A new type of fiber laser modelocking is examined where a phase modulator is driven asynchronously with respect to a harmonic of the roundtrip cavity frequency. An asynchronous drive is able to produce high repetition rate (>1 GHz) soliton pulses that are shorter than the classic, active modelocking pulse width limit. It is shown that with a proper choice of fiber parameters, noise cleanup and soliton pulse shaping can be obtained using filtering and asynchronous phase modulation. Limits of asynchronous detuning are derived and a comparison with the parameters ranges for synchronous phase modulation is also presented.