Design and analysis of polarization beam splitter based on cascaded MMI on SOI

A high extinction ratio polarization beam splitter (PBS) based on cascaded multimode interference couplers is designed on silicon on insulator substrate using 3D beam propagation method (BPM). The numerical simulation tool shows that the polarization extinction ratio is greater than 20 dB for both TE and TM polarizations over C-band wavelength range. The proposed device has insertion loss below 0.8 dB at wavelength 1550 nm for TE and TM polarization. The polarization beam splitter has a compact size and relaxed fabrication tolerance in term of width and length of MMI coupler. These parameters make it as a promising element for polarization diversity circuit and photonic integrated circuits.