We demonstrate the performance of a fiber Fabry-Perot (FFP) interferometer and show how the finesse of the interferometer can be adjusted by changing the operating wavelength. These sensors are extraordinarily sensitive and might have uses for high-density wavelength division multiplexing and high-resolution fiber sensor applications. We cannot resolve the transmission peaks using an optical spectrum analyzer and consequently use a tunable laser diode to study them.
Fiber Bragg gratings act as the mirrors for the FFP interferometer and consist of an optical fiber with a periodic change in the index of refraction.1 The reflectivity spectrum depends on the grating profile. The period of the refractive index profile and therefore the reflectivity spectrum can be changed with stress and temperature. Consequently Bragg gratings are used as sensors for biosensing, civil engineering, and industrial monitoring.