Wavelength-switchable flat-top fiber comb filter based on a Solc type birefringence combination.

In this paper a polarization-independent wavelength-switchable flat-top fiber comb filter is newly proposed, which is based on a Solc type birefringence combination and polarization-diversity loop configuration. The proposed filter consists of a polarization beam splitter, two concatenated polarization-maintaining fibers, and two half-wave plates. Our theoretical analysis shows that the proposed apparatus has a much flatter passband and sharper notch than the conventional Sagnac birefringence filter. Particularly, by interchanging the Solc type birefringence combination within the filter between the folded and fan designs, channel wavelength switching operation, more specifically channel interleaving operation, can be achieved through the proper adjustment of the half-wave plates contained within the apparatus. Theoretical prediction was verified by experimental demonstration.