The more spread out the orbit is the more leverage or influence outside forces have on said orbit...therefore less energy is required to move from one orbit to the next larger one than was required for the prior jump.
Are you excluding the only thing that keeps the light in the fiber is the angle of refraction provided by the difference in R(i) of two mediums glass n1 and n2 (cladding,air,etc..)?
Simply build a small water wheel / human size that someone can step into and walk the wheel around. water is lifted from the bottom of the wheel and released at the top.. can be made from local lumber and is simple enough to be easily maintained.
Just make sure the digital signal is run through an inverter or optical led driver IC that is capable of switching at the required speeds and enough current sink ability to light your led properly...