The Starshot Breakthrough Initiative, sponsored by Yuri Milner, now finances the attempt to use a huge laser on Earth to propell a tiny spacecraft to huge velocity. Not having to carry the energy for its own propulsion, the rocket equation is bypassed. But could such an energy beam from Earth also solve some other of the huge challenges of interstellar travel?
Power. Could a spacecraft transform the energy beam to electric power for use onboard?
Communication. Could the energy beam be modulated to communicate data to the spacecraft and be reflected in a modulating way by the spacecraft's sail to send data back?
Impact prevention. Could parts of the energy beam be focused by parts of the sail to first detect impacting dust grains ahead from their reflections, and the refocused to evaporate them?
Beam reinforcement. Could a convoy of similar sails (without payload) be launched regularly to refocus the energy beam to the next sail ahead?
Deceleration. Could such a convoy or the spacecraft itself, use the energy beam to decellerate the flyby speed?
Teleacope. Could the sail be reconfigured to work as a teleacopic mirror to observe the target star system as it approaches?
Could multiple such functions be performed by a single low mass large area thin sail/photovoltaic/reflector/lens component? I understand that the TRL for this is low, but basic physical challenges and opportunities maybe can be identified anyway.