Investigation on low-temperature characteristics of FBG sensors and the technology to enhance sensitivity
The mode of FBG's temperature-sensing is analyzed to and the low temperature performance of FBG is experimental study. Three package technologies can be used for enhancing the sensitivity of FBG under low temperature; the technologies include capillary steel tube package, metallized package and organic polymer package. The results show that the temperature sensitivity of bare FBG under low temperature is 0.00998 nm /°C, the temperature sensitivity of FBG with capillary steel tube package, metallized package and organic polymer package are 0.0213 nm /°C, 0.0283 nm /°C and 0.1376 nm /°C separately, which are 2.02, 3.30, 10.23 times compared with the bare fiber. The temperature sensitivity of FBG sensor under low temperature could be increased effectively by using package technology.
High resolution cryogenic optical fiber sensor system using erbium-doped fiber
In this paper, we propose a cryogenic optical fiber sensor which can measure temperature at higher resolution using the temperature characteristics of an EDF pumped by a 1480 nm laser diode and modulation of the injection current of the pump laser diode. The measurement resolution considering fluctuations of the light source in the sensor systems is /spl sim/0.4 K near room temperature and /spl sim/0.07 K near liquid nitrogen temperature.
Simultaneous measurement of strain and temperature by use of a single-fiber Bragg grating and an erbium-doped fiber amplifier.
We propose and demonstrate a novel sensor by using a single-fiber Bragg grating that can simultaneously measure strain and temperature with the aid of an erbium-doped fiber amplifier. By using a linear variation in the amplified spontaneous emission power of the erbium-doped fiber amplifier with temperature, we determine the temperature. By subtracting the temperature effect from the fiber Bragg grating Bragg wavelength shift, we determine the strain. Experiments show rms deviations of 18.2 microepsilon and 0.7 degrees C for strain and temperature, respectively.