Adaptive interferometer for detection of mechanical vibrations based on dynamic population grating in Er-doped optical fiber

Simplified schematic of an all-fiber adaptive interferometer in a two-wave mixing (TWM) configuration is applied for detection of mechanical vibrations. This experiment used OFS-Fitel single-mode Er-doped optical fiber HG980. To improve the adaptive properties of the interferometer more, optical pumping of the Er-doped fibers (at 980 nm) could be done, or rare-earth doping elements with shorter spontaneous relaxation times of the metastable level could be utilized.