Time and wavelength multiplexing of fiber Bragg grating sensors using a commercial OTDR

In principle, one way to achieve the desired characteristics of fiber Bragg grating (FBG) based sensors is the combination of wavelength division multiplexing (WDM) with time division multiplexing (TDM). Due to the WDM nature, this approach may lead to systems with very high spatial resolution, down to the millimeter scale, while allowing, through TDM discrimination, the interrogation of up to 100 sensors at a single wavelength. In this contribution, we suggest, and experimentally demonstrate, that the use of a commercial OTDR, combined with a tunable optical filter, provides an inexpensive way of implementing such a system.