Polarization management is of paramount importance in integrated optics, partic-
ularly for highly birefringent photonic platforms such as silicon-on-insulator. In this paper, we
present a polarization beam splitter based on a multimode interference coupler incorporating
tilted subwavelength gratings. The tilt provides accurate control of the structural anisotropy
and enables independent selection of the beat length for two orthogonal polarization states.
As a result, device length is reduced to less than 100 μm while simultaneously achiev-
ing broadband operation through subwavelength grating dispersion engineering. Insertion
losses below 1 dB and an extinction ratio higher than 20 dB are demonstrated through
three-dimensional FDTD simulation in a 131-nm bandwidth.
