  We demonstrate a trade-off between linewidth and loss-of-lock frequency in a
mode-locked laser employing active feedback to control the carrier-envelope
offset phase difference. In frequency metrology applications, the linewidth
translates directly to uncertainty in the measured frequency, while the impact
of lock loss and recovery on the measured frequency is less well understood. We
reduce the dynamics to stochastic differential equations, specifically
diffusion processes, and compare the linearized linewidth to the rate of lock
loss determined by the mean time to exit calculated from large deviation
theory.
