What would modern life be without lasers? They entertain our cats, shape our corneas, destroy our missiles, and distract from the terrible music at B-grade rock concerts. Now they could help us find aliens.
The problem with looking for aliens, other than bothersome probes and anxiety about head size, is balancing the depth and breadth of the search through the night sky for signs of life. Any shift in focus means a corresponding shift in range, and it's tough to find a balance between the two.
A good way to understand this is by imagining yourself on a cliff overlooking an ocean. You can gaze out over the water, but you won't be able to see much detail. Unless what you're looking for is big, you're going to miss it. If you look through a pair of binoculars, you'll be able to see the details up close, but the majesty of the boundless ocean will be lost on you. If the Loch Ness Monster pops up one inch to the left of your field of focus, you won't see a thing.
So what's the cheat, when it comes to astronomy? What would allow us to see any source of communication over a broad range of space? Let's put it this way. Most people today can't tell Vega from Polaris, but they're able to tell Vega from an airliner heading to Miami. Motion and change stands out.
This is where the lasers come in. There are lasers, now, that can produce brighter light than the sun, and can move faster. Sadly, they aren't being used to space-write something cool in the hopes that aliens can read it and be impressed. They're actually not being used much at all. Our new strategy is to set up a detector that takes in broad ranges of the sky in hope that some other planet has been suckered into paying for an unbelievably powerful laser, only to beam out messages into space in the hopes that some other civilization might see them. The ball is in your court, Gliese 581 d. Don't keep us waiting.