A filter device and method are presented for filtering a multi-channel randomly polarized light signal to separate therefrom at least one specific channel. The device comprises a polarizer assembly, and a filter structure. The polarizer assembly is operable for processing the multi-channel randomly polarized light signal to split it into two multi-channel light components of a predetermined polarization identical for both of said two multi-channel light components; and for processing two identically polarized light components to produce a randomly polarized light signal. The filter structure is operable to process said two multi-channel light components of said predetermined polarization to select from each of said two light components the specific channel, and thereby produce two first output light components of the specific channel propagating through spatially separated first light paths.