Design of an ultra-broadband and fabrication-tolerant silicon polarization rotator splitter with SiO2 top cladding

An ultra-broadband and fabrication-tolerant silicon polarization rotator splitter is proposed in this Letter.Benefitting from the broadband and low-loss characteristics of the bi-level taper and counter-tapered coupler,the designed device has a simulated insertion loss and crosstalk of less than 0.2 and -15 dB in the waveband from 1290 to 1610 nm. These characteristics make it valuable in applications with large bandwidth requirements, such as full-grid Coarse wavelength division multiplexer(CWDM) and diplexer/triplexer fiber-to-the-home systems.The fabrication tolerance of the design is also analyzed, showing that the device performance is quite stable with normal manufacturing errors in silicon photonics foundries.