Fiber loop ring-down optical fiber grating gas pressure sensor

A kind of bare fiber Bragg grating (FBG) gas pressure sensor based on fiber loop ring-down is presented, in which there are no sensitizing means or assistant structure on the bare FBG. The pressure sensitivity is analyzed theoretically via discussing the relationship between the ring-down time and the gas pressure. By detecting the ring-down time at different gas pressure levels, the gas pressure characteristics of the bare FBG are investigated in the time domain. The experimental results demonstrate that there exists a linear dependence of the pressure applied to the bare FBG on the ring-down time. A high sensitivity of -0.384 μs/MPa (being equivalent to -240 pm/MPa) could be achieved, which is 79 times larger than that of the optical spectral analyzer interrogated. This kind of pressure sensor could be used for gas or liquid pressure measurement.