Reduction of polarization related effects in superimposed fiber Bragg gratings

Fiber Bragg gratings, and more specifically, superimposed fiber Bragg gratings (SIFBGs), are attractive commercial solutions for several multiband telecommunication applications. However, as a part of a telecommunication system, the polarization dependent properties present in SIFBGs due to the fabrication process dramatically limit their possible implementation in high bit rate optical communications. The development of techniques for the reduction of differential group delay (DGD) and the polarization dependent loss (PDL) in system components is then crucial. We present a simple method to reduce the DGD and the PDL induced during the fabrication of SIFBGs. The proposed fabrication method consists of irradiating the fiber core from different well controlled directions depending on the total number of expositions. We theoretically predict and experimentally demonstrate a reduction of the DGD and the PDL after each illumination.