a wide - band fiber - optic tunable filter is provided . dispersive polymers with different dispersion characteristics and side - polished fibers are used to fabricate wide - band tunable band - pass filters , band - rejection filters , short - wavelength - pass filters or long - wavelength - pass filters . this kind of wide - band fiber - optic tunable fiber filters is able to be used in the applications of fiber - to - the - home system networks . it is also able to be used in the applications of sensitive temperature sensors , high - resolution fiber refractometers , gain - flattened filters , fiber modal filters and fiber mode - field expanders / condensers .