DFB erbium-doped fiber laser with tunable phase shift induced in the laser cavity

In this work, the authors present a study of a DFB erbium-doped fiber laser in which the grating spatial phase shift was induced in the middle point of a uniform FBG (length, 11.5 cm) and was easily tuned with a magnetostrictive transducer at which a short fiber section (4 mm) was glued. The grating was written in a fiber with 1000 ppm concentration of erbium ions. The diffraction efficiencies of both parts of the grating equally divided by the transducer were ~ 98 %. To avoid the fiber cavity nonuniform heating the laser was pumped symmetrically from both grating sides.