It would be possible to detect such a laser from another galaxy as long as someone observes the Earth. True, no one has yet created such a strong laser, but even current lasers can be configured so that they can see radiation from one third of the galaxy's distant ray as observers.
The new study accurately examines these aspects of laser interstellar signals. It speaks of a 1-2 megawatt laser beam that focuses on a radius of 30-45 meters telescope. And yet another technology is not yet, but in the next five years it will become a reality. Such a system would allow for a clear signal to divert six kilobyles – three-quarters of a distance from us to the Galactic Center.
We can pull the signal so that it covers the main zones of the star, so we do not have to apply to any special exoplanet, it is enough to send a signal to the stars. It is theoretically possible to communicate this signal with other civilizations for decades or centuries, depending on the distance to the planet.
In addition, the laser could serve as a per-megabyte data rate channel, so contacting the extraterrestrial civilization could communicate with it. Of course, only if such civilizations are nearby.
The results of the study are published in the astrophysical journal.