LAUSR

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 TM0 mode can evolve into the TE1 mode. Then the TE1 mode is coupled to the TE0 mode at the cross port using the asymmetric directional coupler. The input TE0 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 TE0 mode at the whole C-band. For input TM0 mode, the ER and the EL are, respectively, lower than −10 and 1.5 dB.