Like many elements of sci-fi, the superweapon in Star Wars' Death Star seems implausible: can you really combine multiple laser beams into one fearsome blast? Apparently, you can... if not quite as dramatically as you see in the movies. Scientists have developed a technique that uses diamond to merge multiple laser beams into more powerful ones. The key was to put an exceptionally pure diamond at the point where the beams converge, taking advantage of the crystal's inherent tendency to send the light's power in a specific direction. The material is good at shedding excess heat, too, which is rather important when you're funneling a lot of laser power into a small space.
No, the invention isn't going to be used for destroying rebellious planets. The military could certainly stand to benefit, though. Super-powerful lasers could quickly destroy drones and missiles that normally require a sustained laser attack to take down. There are some more peaceful purposes, too: for a start, spacecraft could use extra-powerful lasers to annihilate oncoming space junk. And when existing single-laser technology is frequently limited by overheating worries, it's likely that there are many other potential uses that just haven't been feasible until now.