Flight Demonstration of a Laser-powered Quadcopter (2010) [pdf]

This is pretty interesting, there is also tons of room for improvement and optimization.

One of the reasons why PV cells are far below their theoretical efficiency, which is something like 93%(Carnot efficiency based on sun temp which doesn't exactly equate to this application but is close enough), is because pv materials have a band gap and waste a lot of the broad-spectrum light energy from a source such as the sun(massive oversimplification).

If this became a thing, it would be plausible for solar pv material guys to put their heads together with laser manufacturers and create a pv/laser combination with absurd efficiency(perhaps >80%). I wasn't able to find the conversion efficiency in the article, I would be interested to know what it was.