Laser skeptics sometimes note that laser proponents over the years have made numerous predictions about when lasers might enter service with DOD, and that these predictions repeatedly have not come to pass. Viewing this record of unfulfilled predictions, skeptics might argue that “lasers are X years in the future—and always will be.”
unquote, link is inside Sep 9, 2015
The same is always said about fusion energy. It should be noted though that lasers, like fusion energy, often get starved of funding periodically.
TRW built Alpha, a megawatt class HF laser designed as for use in orbit in a satellite. It was successfully tested in a vacuum chamber in 1993. The next step would have been to build it to place into space for testing. It's funding was zeroed out in the Clinton years. HF lasers do not emit in the 'window' but reduce the cost of fuel: hydrogen is cheaper than deuterium. It would have been far more useful for forcing aircraft under 30k ft and, thus, limiting their range. Against a peer, not so useful because China or Russia could take out the sats. Enforcing a no fly zone, otoh...
THEL moved forward only as a way to protect Israel from katyushas and whatnot under Clinton. It was discontinued under Bush. The Iraq War funding and technological leakage were both concerns.
The stop and go nature of laser funding has always been an issue, but once you have something in the arsenal, getting it upgraded is much, much easier.