We demonstrate the development of tunable optical filters based on fiber bragg gratings (FBGs). A distributed on fiber resistive heater consisting of a thin metal film is deposited by means of an Electron Beam Evaporator onto the outer surface of an uniform FBG. The physics of heat flow and diffusion in these structures leads to resistive heating of the metal film that follow, to a remarkably good approximation, the local resistance of the coating. This generated heating induces changes in the fiber's refraction index (thermo-optic effect), which together with the thermal expansion effect of fiber causes a shift in the Bragg wavelength thereby achieving the tunability. Experimental results show a dc tuning range of 4.284 nm (nickel as thin film) with a corresponding electrical power of 569 mW. A maximum efficiency of 8.133 nm/W (gold as thin film) was obtained for dc tuning.