Beamforming. The other articles I've seen on using the visible spectrum for communications mostly discuss sending to a mostly stationary object. It's not great for general purpose, but as a wiring replacement, can be rather useful.
Can we use a waveguide for beamforming? Maybe some kind of tube relying on total-internal reflection to guide our light around sharp corners?
i'm no computer scientist, but don't i have to request information in order to receive it?
What i mean is, do i have to attach a LED light to my laptop to request the data from the LED in my roof?
Yes and no. One could just receive broadcasted data -- a monitor on the other side of the room really doesn't need to send much info back. For a laptop, one wouldn't necessarily need to request data via an LED, the requests could be made over some other medium, like traditional wifi, with the responses coming from the LED.