We experimentally demonstrate optical filtering, polarization splitting and rotating, and mode (de)multiplexing and switching in silicon devices.

We firstly demonstrate silicon photonic filters based on Sagnac loop reflectors, including a wavelength and bandwidth-tunable comb filter, and two compact interleavers in the Michaelson interferometer and interfering loop configurations with compact footprints.

We then discuss a high extinction-ratio (30 dB) silicon polarization beam splitter (PBS) based on a grating-assisted contra-directional coupler (GACC), and an ultra-compact silicon polarization splitter and rotator (PSR) with a short coupling length of 8.77 micron.

We further talk about optical switching in wavelength, mode, and polarization. We demonstrate a 2x2 nanobeam thermal-optic switch with ultra-small mode volumes, a high tuning efficiency of 1.23 nm/mW and an ultra-low switching power of 0.16 mW. We then propose a mode- and polarization-selective switch (MPSS) architecture for next generation high capacity switching systems, and demonstrate 1x2 and 2x2 on-chip MPSS switches.