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