Note: The spelling 'fiber optics' is also used in American English. The form 'fibre optic' is used as a modifier.
1.
Fibre optics is the use of long thin threads of glass to carry information in the form of light.
N-UNCOUNT
2.
Fibre optic means relating to or involved in fibre optics.
...fibre optic cables.
ADJ : ADJ n