Online calibration of PZT driven fiber Fabry–Perot filter nonlinearity using FBG array and PSO algorithm

The nonlinearity of a piezo-electrical transducer (PZT) driven fiber Fabry–Perot filter (FFP) is investigated and calibrated using a group of fiber Bragg gratings (FBGs). The peak positions of four series FBGs are used as wavelength references and detected by particle swarm optimization (PSO) algorithm with high accuracy and less computation time. Polynomial fit is employed to model the wavelength–voltage relationship of FFP. The absolute error in wavelength detection using the calibrated FFP is demonstrated by experiments to be as low as 25 pm. The wavelength resolution of FFP has also been studied by scanning the absorption spectrum of acetylene. The proposed approach of online calibrating the wavelength–voltage relationship of FFP has great potentials in applications where FFP is used as wavelength demodulator.