The study analyzes phase performance in a fiber optic temperature sensor using mode-division multiplexing. In the simulation, the single mode fiber is polished to remove most of the cladding, and then gold and silver films are added. Finally, it is embedded in the heat shrinkable tube. Since the measuring chain is a functional combination of optical methods, optical fiber properties, and other photonic elements together with control electronic circuits, it is necessary to nd a suitable compromise between the chosen measurement method, fi measuring range, accuracy, and resolution.