Synchronization between two fixed cavity mode locked lasers

An active mode locked fibre ring laser is designed as a slave laser, driven by a commercial Ti:Sapphire laser acting as a master. The master-slave synchronization was stabilized for frequency detuning, but the output pulse width of the slave laser was observed to increase. The increase in pulse width was asymmetric about the ring cavity resonance frequency, a consequence of an asymmetry in the detuning range of the higher order cavity modes. We find that the detuning range decreases as the square of the mode number, in agreement with theory.