An IR sensor "sees" the IR signal from any remote and turns it into an electrical signal. Inside the cabinet, the electrical signal is turned into IR again by having the signal turn LEDs on and off at the same rate as the original remote control's IR emitting LED.
This is WAY more flexible than any fiber optic system could be -- I am finishing up a home where there are three sensors in the living room that has both a TV and a projection system in different areas, as well as a whole-house audio system, and you can control the whole-house system from the main rooms and the three bedrooms via IR remote controls; there are also five locations where keypads have been programmed to issue macros, or sequences, of the electrical analog of the IR signal; this gets turned into IR as well, so the house system is controlled via IR from both keypads and remote controls.
And a couple of the zones of the curtain IR controls are used to turn the two fireplaces on and off.....
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
