The main feature of this sensor is, it gives distributed sensing above long-range distances. Once the information arrives at the black box, then it produces a light signal. A fiber-optic sensor is a sensor that uses optical fiber either as the sensing element ("intrinsic sensors"), or as a means of relaying signals from a remote sensor to the electronics that process the signals ("extrinsic sensors"). This signal can then be measured by an instrument or interpreted by a user. For example, a thermocouple is a sensor that detects. The fiber optic sensor working principle is that transducer changes some optical fiber system parameters like wavelength, intensity, phase, polarization, etc.