I am a new user of Lumerical products. I was trying to solve a polarization rotator design using FDE and EME solvers. My simulation shows the fundamental and coupled supermodes and corresponding effective indices for those modes. Mode field distributions look similar to what we expect but the coupling length calculation from those supermodes effective indices is not matching with the published results (paper attached). The paper shows the coupling length = 134.50 um but we are getting around 128 um. I simulated the propagation with the EME solver but still got the same less accurate result. I solved the waveguide structure with our in-house FEM mode solver and the results agreeing well with the published results. I tried to increase the mesh size but the results are still not accurate. Could you please help me to rectify the problem in my program? The program and the paper are attached with the post.
PR at 1.55 um_JLT paper_Barh et al.pdf (755.5 KB)