No Copper in Fiber Optic Cables

I asked the question on Lost Coast Outpost after they severed the fiber optic cables in Hopland a while back: Do fiber optic cables contain copper, or did the bad guys just think they do? Nobody answered. 

The Santa Rosa Press- Democrat seems to have answered my question today: "Investigators believe the would-be thieves were seeking copper wire and abandoned the severed, partially unstrung cable — an estimated 700 feet — after realizing it wasn’t copper." 

They probably had no idea it was a fiber optic cable. Just something used by the phone company so assumed it contained copper.