The improvement of temperature sensitivity by controlling the thermal expansion coefficient of no-core fiber

Abstract

In this paper, a liquid sealed temperature sensor is assembled based on single-mode-no-core-single-mode (SNCS) optical fiber structure. Theoretical calculations and experiments verify the sensing characteristics of this structure. The structure improves the temperature sensitivity to −355 pm/°C by encapsulating an organic solvent with large thermal optical coefficient and using packaging material with large thermal expansion coefficient. The theoretical results are in good agreement with the experimental results. Theoretical simulations are completed on MATLAB using far from the cut-off condition. The SNCS structure is encapsulated in a microfluidic chamber by applying microfluidic processing technology. The axial thermal expansion coefficient of the no-core fiber (NCF) is increased and radial thermal expansion coefficient is suppressed by the polydimethylsiloxane (PDMS) mold stretching NCF to improve the temperature sensitivity. The enhancement effect of PDMS stretching NCF on temperature sensitivity is verified by contrast experiment. Due to the wrapping of PDMS, the sensor has strong resistance to mechanical damage and external interference.