Hybrid sensor based on a single segment of hollow-core microstructured optical fiber for simultaneous measurement of pressure and temperature

In this work, we present the development of a novel hybrid optical fiber sensor designed for the simultaneous measurement of pressure and temperature. The sensor consists of a short section of hollow-core microstructured fiber (HCMF) spliced to standard single mode fiber. In the splice region an air bubble is created, forming two Fabry-Perot interferometers, one in air and the other one occurring in silica cavities. The manufacturing process is straightforward and cost-effective, requiring only a fusion splicer, making it suitable for scalable production. The sensor displays distinct sensitivities for each parameter, with the air cavity exhibiting a pressure sensitivity of (4.01 ± 0.04) nm/MPa and temperature sensitivity of (0.66 ± 0.06) pm/°C, while the silica cavity demonstrates a pressure sensitivity of (0.914 ± 0.004) nm/MPa and a temperature sensitivity of (8.27 ± 0.07) pm/°C. These results underscore the sensor capability to independently measure pressure and temperature variations with high precision, providing a robust solution for multi-parameter sensing in a range of applications.