John shares his knowledge of fiber optics by answering your specific questions
How can I trace the path of buried loose tube fiber? Unlike copper wire, which can be traced with a metal detector, there is usually no metal in loose tube?
This shouldn't be a problem if the original installer made provisions for tracing the fiber. He or she may have installed metallic marker tape, which is typically buried about one foot above the fiber.
Another option for the installer is to use armored outdoor fiber optic cable. Although this type of cable is used mostly for rodent protection, the metallic armor makes the cable easy to detect.