Wide-Dynamic-Range High-Resolution Fiber Fabry–Perot Interferometric Sensor With Chirped Fiber Bragg Gratings

We present a novel optical fiber sensor based on a Fabry-Perot interferometer with chirped fiber Bragg gratings (CFBG-FPI) using a narrow wavelength sweep range. In a fiber Bragg grating (FBG) sensor, wavelength shifts in the reflection spectrum are detected. Using a fiber Fabry-Perot interferometer with FBGs (FBG-FPI), the resolution can be improved, but its dynamic range is reduced. Here, a CFBG-FPI is used to expand the dynamic range. It has many sharp transmittance peaks in its wide reflection band. Combining precise detection of the position of a transmittance peak position in a narrow wavelength sweep with the change in the number of peaks entering the sweep range, measurements as precise as FBG-FPI sensors are achieved over a wide dynamic range, a hundred times larger than that of FBG-FPI sensors.