Optically tunable long-period fiber grating on an Er³⁺ fiber

An optically tunable long-period grating (LPG) on an erbium-doped fiber (EDF) is experimentally demonstrated. It is based on the core refractive index changes induced by the pump power on an LPG written in the EDF core. With an optimized design of the LPG, a shift of 5.5 nm of the attenuation band wavelength is obtained with a pump power of 100 mW at 1480 nm