[modeless]

The article states that the reaction produced more energy than the fuel absorbed, not more energy than it took to run the lasers. I expect the efficiency of power transfer to the fuel is pretty low.

[lambdatronics]

You're right, they had 1.8 MJ of photons hitting the target, but something like 400MJ of energy going into the laser, which is inefficient (<1%).

[modeless]

Wow, I didn't guess that low. I guess it makes sense though.

[jatone]

also mentioned chain reactions which would be one way to generate more energy than input even if your input was high.