Temperature Sensor Based on Periodically Tapered Optical Fibers

In this paper, the fabrication and characterization of a temperature sensor based on periodically tapered optical fibers (PTOF) are presented. The relation between the geometry of the sensors and sensing ability was investigated in order to find the relatively simple structure of a sensor. Four types of PTOF structures with two, four, six and eight waists were manufactured with the fusion splicer. For each PTOF type, the theoretical free spectral range (FSR) was calculated and compared with measurements. The experiments were conducted for a temperature range of 20-70 degrees C. The results proved that the number of the tapered regions in PTOF is crucial, because some of the investigated structures did not exhibit the temperature response. The interference occurring inside the structures with two and four waists was found be too weak and, therefore, the transmission dip was hardly visible. We proved that sensors with a low number of tapered regions cannot be considered as a temperature sensor. Sufficiently more valuable results were obtained for the last two types of PTOF, where the sensor's sensitivity was equal to 0.07 dB/degrees C with an excellent linear fitting (R-2 > 0.99). The transmission dip shift can be described by a linear function (R-2 > 0.97) with a slope alpha > 0.39 nm/degrees C.

Automated summary

This paper presents the fabrication and characterization of a temperature sensor based on periodically tapered optical fibers (PTOF). The study investigates the relation between the geometry of the sensors and sensing ability, emphasizing the importance of the number of tapered regions in PTOF for temperature response. Results show that sensors with a low number of tapered regions cannot be considered effective for temperature sensing, while sensors with more tapered regions demonstrate excellent sensitivity and linear fitting.