Waveguide devices based on nonbirefringent substrates may still have form birefringence if index discontinuities exist. It is demonstrated that the semivectorial beam propagation method can be used to study the polarization dependence in waveguide devices. It is shown that the calculated coupling lengths of planar directional couplers match within 3.5% of analytical solutions. Results on polarization dependencies of coupling lengths and bending losses of rib waveguide devices are presented. Results of rib waveguide directional couplers indicate that the form birefringence can be significant. Losses of S-shaped bends are weakly polarization dependent in the low-loss regime.
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