Time- and Wavelength-Division Multiplexed Heterodyne Detection Applied to FBG Interrogation

We report time- and wavelength-division multiplexing of fiber Bragg gratings interrogation based on heterodyne detection. A directly modulated distributed-feedback laser array is used as a multi-wavelength, frequency scanning, pulsed-light source. A heterodyne detection technique is used to increase the signal-to-noise ratio of weak reflections. Reflection spectra of 10 fiber Bragg gratings with three different wavelengths are simultaneously observed with high signal-to-noise ratios.