Philip Lubin describes his appraoch to achieving laser driving spacecraft propulsion in the near term

100kg robotic craft could be sent to Mars in 3 days
1kg could go overnight to Mars
50-100 GW could send a wafercraft to 30% of the speed of light and i would involve 10 minutes

A system that is about 100 times the mass of the space station would be able to launch such missions to Mars or interstellar wafercraft.

So fully reusable Spacex rockets would be able to affordably launch such a system into space in the 2020s