Design of a C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler

摘要

A C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed. The mode-evolution structure is designed in a bi-level taper through which the TM_0 mode can evolve into the TE_1 mode. Then the TE_1 mode is coupled to the TE_0 mode at the cross port using the asymmetric directional coupler. The input TE_0 mode propagates along the waveguide without mode conversion and output at the through port. From the experimental results, the extinction ratio is lower than 30 dB and the excess loss is less than 1 dB for input TE_0 mode at the whole C-band. For input TM_0 mode, the ER and the EL are, respectively, lower than ?10 and 1.5 dB.