  Two mutually coupled chaotic diode lasers exhibit stable isochronal
synchronization in the presence of self feedback. When the mutual communication
between the lasers is discontinued by a shutter and the two uncoupled lasers
are subject to self-feedback only, the desynchronization time is found to scale
as $A_d\tau$ where $A_d>1$ and $\tau$ corresponds to the optical distance
between the lasers. Prior to synchronization, when the two lasers are
uncorrelated and the shutter between them is opened, the synchronization time
is found to be much shorter, though still proportional to $\tau$. As a
consequence of these results, the synchronization is not significantly altered
if the shutter is opend/closed faster than the desynchronization time.
Experiments in which the coupling between two chaotic-synchronized diode lasers
is modulated with an electro-optic shutter are found to be consistent with the
results of numerical simulations.
