If you want to go high bandwidth, fiber optics is the way to go.
From trans-oceanic cables to the yet-unseen ‘fiber to every
home,’ fiber optics allows a lot more bandwidth than a copper
cable. In low-bandwidth applications, fiber optic cable
transmits data using one color of light. There’s a way to get
more bandwidth out of a fiber optic cable, as [Shahriar] found
out while experimenting with an RGB LED. For his experiment,
[Shahriar] used a BlinkM programmable RGB LED and a Sparkfun
color sensor. In fiber optic lines with one light, it is
possible to send many simultaneously using PWM, but noise
becomes a problem at high data rates. Using an RGB LED,
[Shahriar] sends three levels of Red, Green, and Blue to
transmit 9 bits at a time – perfect for sending a byte with a
parity check in one quick light burst. [Shahriar]‘s technique is
exactly how the pros pump massive amounts of data through a
single fiber optic cable. All the tools, code, and MATLAB
functions are available on [Shahriar]‘s site, ready to be use