Original question:
Can we use fire optic cable for connecting antennas to communication equipment?
As I understand it, is then NO electronic active circuits allowed between optical fiber and antenna, such as (de)modulators.
The optical fiber is also assumed to have a effective diameter much less then common radio wavelengths.
It is not impossible but very ineffective to use a conventional waveguide designed for optical frequencies for transferring RF waves.
Cladding in a glass fiber is normally carbon based that absorbs RF signals and fiber core is too thin for most RF wavelengths.
Another hypothetical possibility require that RF energy must be high enough to be able to charge and emit photons or other elementary particles.
There are however several more realistic solutions that not have active electronics at a receiving RF antenna end. A active electronic demodulator exist, but
not at antenna location.
A few years ago was following two similar systems hot topic:
EMPiRe - Electro-Magnetic Pulse Tolerant Microwave Receiver (DARPA)
ADNERF - All Dielectric Non Electronic Radio Front End
Main advantage is that RF antenna can be placed several miles away from RF receiver and the receiver can be placed in an EMP protected environment.
System loss is around 10-20 dB, but as R&D is mostly of military interest, improvement can have been done that not is official.
By adding RF sensitive nano structures, in the fiber core or cladding or at fiber end can similar effect be achieved and it is ongoing research in this field as it can be an cost effective alternative for modulating/transferring commercial +100GHz wide band RF.