Have you figured out how to configure the checks if fiber link is operational and if cable link is operational? If you have a plugin that says you that then it should be easy.
You then write a script that would check for the fiber link, and report OK if it is up, report WARNING if it is down and the cable is up, and give a CRITICAL if both of them are down.
Is that a remote device that you're trying to check? You should be more specific maybe. If it is snmp accessible then it could be done by checking the states of the fiber and cable interfaces of that device.