Design and analysis of polarization independent MMI based power splitter for PICs

An ultracompact and low loss polarization-independent 1 x 2 power splitter based on multimode interference (MMI) is designed and analyzed using Eigenmode expansion (EME) and variational FDTD method on silicon on insulator. The numerical tool shows that the excess loss of the power splitter is 0.04 dB for TE and 0.06 dB for TM polarization at wavelength 1550 nm while the polarization differential loss (PDL) is < 0.07 dB over wavelength 1500 nm-1600 nm. Moreover, the optimized MMI structure has a fabrication tolerance of width +/- 150 nm and a length of +/- 800 nm. In addition, polarization-independent arbitrary power splitter (APS) is designed using cascaded MMI and tapered waveguide as a phase shifter having excess loss < 0.16 dB for TE and <0.21 dB for TM mode at wavelength 1550 nm. The proposed devices have broad applications in optical interconnect and switches for PICs.