  Yes, it is possible to phase lock 25 fiber lasers but only for a short time.
Our experiments on passively phase locking two-dimensional arrays of coupled
fiber lasers reveal that the average phase locking level of 25 lasers is low
($20%-30%$) but can exceed 90% on rare instantaneous events. The average phase
locking level was found to decrease for larger number of lasers in the array
and increase with the connectivity of the array.
