An interrogation system based on two semiconductor optical amplifiers for weak fiber Bragg gratings

An interrogation system based on two semiconductor optical amplifiers for weak fiber Bragg gratings(FBGs) was proposed in this study. The first Semiconductor Optical Amplifier (SOA) was used to modulate the light and the second SOA separated the signal through delayed switching. The proposed system has lower insertion loss and higher spatial resolution, and can interrogate time-division and wavelength-division multiplexed FBG array. Up to 50 FBGs, with a reflectivity of 0.2% and a spatial resolution of 5m along the optical fiber, were distinguished to demonstrate the interrogation system.