Calibration and Demodulation for Signals in FBG- interrogator Based on Photonic Integrated Circuit

Spectral characteristics of a photonic integrated circuit are investigated in the paper. The fiber-coupled photonic integrated circuit is a basic spectral element in the interrogator for sensors based on fiber Bragg gratings. The principle of operation of the indium phosphide based photonic integrated circuit is based on rough and fine spectral filtration. The rough and fine spectral filtration is performed by an eight channel Arrayed Waveguide Grating filter and Mach-Zehnder interferometers respectively. The signal from the Arrayed Waveguide Grating is connected with the interferometers via an optical switch. In this work, a study of the spectral characteristics of the circuit is carried out and an analytical description of the signals and approaches to finding analytical calibration coefficients are proposed. The description is used for the task of calibration and further signal demodulation with the photonic integrated circuit. The demodulation accuracy of the test signal is estimated as 100 pm.