From a comparison between Fig. 1(a) and Fig. 1(b), it can be determined that the side polishing process has a great influence on the light transmission within the SPMMF.
As the F-P spectrum and FBG spectrum response independently to each other, the temperature cross-sensitivity problem has been resolved.
The sensitivity of this sensor was estimated to be 0.10 nm/%RH with negligible hysteresis (o1% RH).
A humidity sensor based on Fabry–Perot interferometer (FPI) and intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated.
The proposed sensor has a great potential in high-capacity sensor network and remote detections.
The experiment shows that the relative output power of the fiber laser has a good linear response to ambient humidity in a wide range from 25%RH to 95%RH.