Comment by dreamcompiler

Doppler is not a big problem with lasers because the carrier frequency is so much higher than RF that it doesn't matter; it's bang-bang AM modulated.

I'm assuming two things: That something like Manchester coding is being used so that some clock skew is tolerable, and that the laser carrier is not in fact being frequency or phase modulated. Last I checked FM and PM of optical frequencies was not yet practical outside of laboratories, but I'm happy to be corrected.