Inline conversion filter capable of selecting reflection and transmission spectra of different bragg gratings using polarization-diversity loop

In this paper, we have demonstrated an inline conversion of transmission or reflection spectra of two fiber Bragg gratings (FBGs) having a different Bragg wavelength by incorporating a polarization-diversity loop without reconfiguring the filter structure. The proposed apparatus consists of a fiber-pigtailed polarization beam splitter, two FBGs, and three quarter-wave plates (QWPs). Without requiring reconnect of input/output ports or additional optical switches, the spectral selecting operation of the FBGs were carried out through proper adjustment of the QWPs contained in the proposed filter.