Technology already exists that can produce extremely short laser pulses of petaWatts (1015 Watts). If one couples this to a large optical telescope like the 10-meter Keck, which is used like a searchlight mirror, there is an efficient system of directing nanosecond laser pulses at other interstellar civilizations. Laser light produced like this and directed toward the solar system would easily outshine the light from the star from which the light originated. According to Bhathal, the nanosecond laser pulse would appear about 5,000-7,000 times brighter than the background light from the ETI star. This fact is independent of distance, since both the laser light and the light from the ETI star will diminish at about the same rate with distance.
http://www.cosmiverse.com/space03010201.html
