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Photonic Crystal Fiber Transducers for an Optical Fiber Multilevel Temperature Threshold Sensor

Thermo-optical properties of the optical fiber transducers based on a filled Photonic Crystal Fiber used as a temperature threshold sensor were shown in this paper. A simple transducer is a piece of a partially filled PCF spliced with a standard single-mode fibers. As a filling material, a selected group of n-alkanes with the carbon atoms’ number within the range of 12–28 were used. The main advantages of these materials are phase transitions between solid and liquid states for temperatures from −10 up to 60 °C. Each transducer has a bistable switch on/off transmission characteristics depended on a given n-alkane physical state liquid or solid. These properties allow us to propose an optical warning system as a multilevel temperature threshold sensor. This system can be used in industrial applications to control temperature as a point sensor.