Fabrication and Optical Characterization of Low-Loss Barium Titanate Waveguides

This paper presents low-loss monolithic Barium Titanium Oxide (BaTiO3), hereafter referred to as BTO, waveguides fabricated on a Silicon-on-insulator (SOI) platform, using a novel measurement approach based on optical back-scattering reflectometry (OBR). Utilizing this method, a low average propagation loss of 0.7 dB/cm was achieved for a straight waveguide which, to our knowledge, is the lowest propagation loss reported to date based on long BTO ridge-waveguides. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) highlight the smooth sidewalls responsible for lowering the waveguide loss. Design simulations and fabrication processes are presented, followed by optical characterization.