Optic fibers, stripped of their jacket, weakened and embedded in a composite plate structure, cracked due to the occurrence of cracks and delaminations in the composite. At the location of a crack in a fiber, transmitted laser-light energy was converted into thermal energy, causing the temperature in the neighborhood of the crack to rise. The temperature change was detected with the aid of an infrared camera. Dynamic numerical simulations of the heat development in the vicinity of the fiber crack were performed. An analytical solution of the temperature distribution on the surface of the composite plate above a fiber crack was also developed. Both analytical and numerical results showed the feasibility of detecting and monitoring the hot spot on the composite plate caused by optic fiber cracking, by use of infrared emission from the fibers. This was successfully confirmed in experiment. The influence of parameters such as depth of the fiber below the surface of the plate, heat conductivity coefficient and light power, on the temperature distribution was also studied. Ultrasound scan of the damaged plate confirmed the accuracy of the hot-spot method in defining the damaged area.