Graded-index core-based polarization dependence beam splitters realized with symmetric polymer directional couplers

In this paper, we design and demonstrate polymer-based polarization dependence beam splitters realized with graded-index (GI) parabolic directional couplers at 1550 nm. We investigate these directional couplers by using the beam propagation method (BPM) and the RSoft CAD BeamPROP solver is used for model design and characterization. We investigate the splitting ratio of 50:50 and 100:0 of these beam splitters for both TE and TM modes. In particular, the 50:50 beam splitters exhibit an output efficiency of 95% due to the absence of polarization. However, in presence of the polarization effect, the polarization dependency is analyzed and manipulated successfully, and the input intensity increases by approximately 98% at an incident angle of 31° due to the polarized launch field. Moreover, the 100:0 beam splitters act as the switching devices realized with GI polymer directional couplers. The insertion losses of the GI splitters are 0.162 dB and 0.186 dB, while the excess losses are 0.148 dB and 0.149 dB for TE and TM modes, respectively. Also, the polarization extinction ratio (PER) of the 100:0 beam splitters is >25 dB and >20 dB for TE and TM modes, respectively.