Faster Than The Speed Of Light?

[JimC]

The energy loss of the photons would be due to a gradual increase in their wavelength after each bounce from a surface accelerating away from them.

[mistermack]

The energy loss of the photons would be due to a gradual increase in their wavelength after each bounce from a surface accelerating away from them.

Yeh, it would gradually get redder with each reflection. But going on what that wiki page says, it's still 1000 times more energy efficient than just using the light once. Because you can bounce the light so many times, you reduce the losses of generating the light enormously.
To maintain acceleration, you just have to either amplify the light using a tiny bit of energy on each reflective cycle, or constantly dribble in new light to make up for the energy-depleted redder light.