An all-fiber tunable filter device that uses a resistive fiber coating to directly heat an intra-core Bragg grating is presented. Bragg gratings were fabricated in a hydrogen-loaded standard telecommunication fiber by a KrF excimer laser with a fluence of 50 mJ/cm2 per pulse. Electrical connections were realized with gold wires at the ends of the coated section and a total resistance of 38 Ω was measured. A large wavelength tuning range of 2.15 nm was obtained by application of a low electrical power of 0.54 W.