High Sensitivity Fabry-Perot Interferometric Temperature Sensor Based on Three Different Microcavity States

A temperature sensing system based on the Fabry-Perot interference structure is designed. Air, distilled water, 5% NaCl solution, absolute ethanol, methanol and cured silicon rubber are used as the temperature sensitive materials of the sensor to improve the temperature sensitivity effectively. The experimental results show that when the medium in the cavity is air, the temperature sensitivity of the F-P interference structure is inversely proportional to the cavity length. However, when the medium in the cavity is liquid or the solid material constitutes F-P type detection probe, the length of the cavity will hardly affects the temperature sensitivity of the structure. Because at this time the main reason of the wavelength shift is the change of material's thermo-optical coefficient, the temperature sensitivity is proportional to it. In the experiment, methanol is the liquid with the highest absolute value of the thermo-optical coefficient. And when it is filled with F-P cavity, the temperature sensitivity is - 564 pm/degrees C. In addition, when the cured silicone rubber is used as an F-P type detection probe directly, the temperature sensitivity can be as high as 1.15 nm/degrees C. The temperature sensing structure has the advantages of small size, good repeatability, strong flexibility and plasticity, and has potential application values in the field of temperature sensing in the future.