Time- and wavelength-division multiplexed interrogation of fiber Bragg gratings based on dual-wavelength differential detection

The dual-wavelength differential detection technique is used to interrogate fiber Bragg grating sensors. A directly modulated distributed-feedback laser array acts as a multi-wavelength, frequency-scanning pulsed light source. Pulse pairs with frequency drift and identical intensities are generated at three wavelengths. By interrogating 10 serially connected Bragg gratings at the three wavelengths using these pulse trains, we realize a time- and wavelength-division multiplexed temperature sensor system based on dual-wavelength differential detection using a simple setup.