In-line tunable band-edge filter based on a single-mode tapered fiber coated with a dispersive material

We report the use of a single-mode tapered fiber coated with a dispersive material as a tunable band-edge filter. The band-edge wavelength can be adjusted, over a range of /spl sim/500 nm (1150-1650 nm), in a simple way with the taper waist diameter, the interaction length, or with the refractive index of the dispersive material that coats the taper. Moreover, the fabrication procedure is simple and of low cost.