https://www.cnet.com/news/mit-researchers-lasers-could-send-bat-signal-to-alien-astronomers/

"The kinds of lasers and telescopes that are being built today can produce a detectable signal, so that an astronomer could take one look at our star and immediately see something unusual about its spectrum," author James Clark, a graduate student in MIT's Department of Aeronautics and Astronautics, said in a statement this week. "I don't know if intelligent creatures around the sun would be their first guess, but it would certainly attract further attention."  

The research came out Monday in The Astrophysical Journal. It suggests that a 1- to 2-megawatt laser could be pointed through the mirrors of a massive telescope -- like the controversial Thirty Meter Telescope planned for Hawaii -- and shot into space to produce a planetary-scale lighthouse.