A fiber optic communication system including a fiber optic link, a transmitter system and a receiver system. The transmitter system includes a laser source producing a light beam, and a polarization controller receiving the light beam and providing an expected pattern of changing states of polarization to the light beam to output light signals into the fiber optic link to cause the expected pattern of changing states of polarization to be transmitted along the fiber optic link. The receiver system is provided with a polarization analyzer, and a light detector. The light detector receives the light signals transmitted by the transmitter, and forwards data indicative of the light signals to the polarization analyzer. The polarization analyzer analyzing the data with an inverse polarization reference frame and generates an alert based on deviations of the data from the expected pattern of changing states of polarization.