摘要
We describe a polarization rotator based on a parallel-core structure consisting of a silicon nanowire waveguide and a silicon-nitride waveguide.The 60-μm-long rotator provides a polarization extinction ratio of more than 10 dB with excess loss of less than 1 dB.In addition,the extremely wide bandwidth of more than 150 nm expected from calculations is confirmed in experiments.A study of the fabrication tolerance of our rotator indicates that fabrication error of around 25 nm is allowable.