There are two main options for repairing a broken fiber optic cable. Either splice the two broken ends together mechanically, using an optical gel, or fuse the ends back together through a process that uses heat.
The first step to fixing fiber optic cable is exposing the source of the problem. Slit the cable with a cable stripper to expose the inside, and then use a knife or scissors to peel back the protective layering that covers the fiber optic bundles at the center of the cable. Use alcohol to get rid of the protective gel covering the wires in the bundle.
The next important task is to remove all of the buffer tube with the alcohol. Continue wiping the fiber until you hear a squeaking sound, then cut the fiber to the length that you need using a cleaving device.
Lastly, use a tool called a mechanical splice tray to reattach the broken ends of the fiber optic cable together. Slide or snap the two ends of the cable into place on the splice tray, and allow the device to use either the optical gel method or the fusion method to firmly reattach the cable ends. Remember to put heat-shrink tubing over the finished work.