Non-volatile 2 × 2 optical switch using multimode interference in an SbSe-loaded waveguide.

We propose a non-volatile 2 × 2 photonic switch based on multimode interference in an SbSe-loaded waveguide. The different modal symmetries of the TE and TE modes supported in the multimode region change their propagation constants distinctly upon the SbSe phase transition. Through careful optical design and FDTD optimization of the multimode waveguide dimensions, efficient switching is achieved despite the modest index contrast of SbSe relative to GeSbTe. The fabricated optical switch demonstrates favorable characteristics, including low insertion loss of ∼1 dB, a compact length of ∼27 µm, and small cross talk below -15 dB across a 35 nm bandwidth. Such non-volatile and broadband components will be critical for future high-density programmable photonic-integrated circuits for optical communications and signal processing.