This sounds like one of those posts that have lost something in the translation! Optical fibers can, in general, handle tens of killowatts...if the power is OPTICAL, ie. like at 1550 nm!
I do not know what you mean by an optical matching network at Sband. You are way too low in frequency to propagate anything at Sband on and optical fiber directly. Are you confusing sending microwaves down the fiber, which you can not do, with sending light down the fiber that is modulated by microwave frequencies, which you can do?