Waveguide design optimization for compact silicon photonic ferroelectric phase shifters

In this paper, a new, to the best of our knowledge, design for a ferroelectric BaTiO3 cladded silicon photonic phase shifter with very small switching length for compact photonic integrated circuits (PICs) is proposed. The proposed design is based on the choice of a waveguide core with suitably slanted sidewalls in order to favor the desired polarization of ferroelectric cladding and to make guided modes spread toward the ferroelectric cladding with the consequence of further reduction in switching length compared to the conventional (rectangular core) structure. The proposed design also gives the additional benefit of having the identical switching length for both TE and TM modes with the same configuration. These results offer a viable strategy to realize compact non-volatile phase shifters for reconfigurable and programmable PICs.