Highly Variable FBG Interrogator With Electro-Optical Attenuation and Time Delay

In this letter, we present a Fiber-Bragg Grating (FBG) interrogator combining wavelength and time division multiplexing to increase the number of interrogation up to 800 independent gratings. The unit consists of a super luminescent light emitting diode, a variable electro-optical attenuator and a spectrometer. The wavelength range is 85 nm spanning through the S, C, and L optical communication bands. High variability is assured by independent settings of time delay and optional signal enhancement for each individual time window with simultaneous wavelength multiplexing. The variability of the setup is advantageous for such an application as in civil and mechanical engineering where large numbers of gratings or groups of gratings are used and allows to measure a wide range of setups of FBGs.