Fabrication-Tolerant Half-Ridge InP/InGaAsP Polarization Rotator With Etching-Stop Layer

Highly efficient and fabrication-error-resistant InP/ InGaAsP polarization rotator based on the half-ridge waveguide is experimentally demonstrated. A thin InAlAs layer is embedded inside the InGaAsP core layer to provide 20-fold etching selectivity with respect to InGaAsP, enabling precise control of the dry-etched core layer thickness. The designed device is fabricated to show a high polarization conversion efficiency of more than 95% with a large etching time tolerance of ±16%. Demonstrated scheme offers a practical path towards realizing compact and low-cost InP-based monolithic dual-polarization transceivers with on-chip polarization (de)multiplexers.