  We present and experimentally demonstrate a technique for achieving and
maintaining a global state of identical synchrony of an arbitrary network of
chaotic oscillators even when the coupling strengths are unknown and
time-varying. At each node an adaptive synchronization algorithm dynamically
estimates the current strength of the net coupling signal to that node. We
experimentally demonstrate this scheme in a network of three bidirectionally
coupled chaotic optoelectronic feedback loops and we present numerical
simulations showing its application in larger networks. The stability of the
synchronous state for arbitrary coupling topologies is analyzed via a master
stability function approach.
