What advantages does Fiber-optic communication have over electrical transmission?
Fiberoptics can carry many times the number of calls as copper wire and is less prone to electromagnetic interference.
Why? Fiber optics uses light in the deep infared with a typical frequency of around 200 trillion Hertz (cycles per second). Copper wire can handle frequencies in the Megahertz range. For a simple comparison, let's call that 200 million Hertz. ("Mega" means million)
The greater the frequency, the greater the "bandwidth" and the more information can be carried. I'm going to oversimplify here to explain bandwidth, but the gist is that you can split the 200 million Hertz of copper wire into 200 separate frequencies of one million hertz each, but the 200 trillion Hertz frequency of fiber optics can be split into 200 million separate frequencies of one million each! So fiber optics can carry way more signals. In practice that difference isn't so great but it's improving each year.
And the electromagnetic interference? The size of the signal in copper wire can be greatly altered be a passing EM wave, reducing or eliminating the signal. Something very dangerous for aircraft.
Fiber optics uses pulses (digital) and so the strength of the signal is less important as long as it can still be detected.