In this letter, we have fabricated a thin TiO2 core and electro-optic (EO) polymer cladding derived rib-waveguide and demonstrated its optical modulation at 1550 nm with a VπL figure of merit of 3.3 V cm. We utilized the high refractive index TiO2 to confine a large fraction of light in the relatively low refractive index EO polymer layer. Furthermore, this TiO2 core enables the modulator to be constituted without a transparent top cladding and also can increase the EO activity to a much higher level. As a result, the waveguide has an enhanced in-device r33, corresponding to a VπL of 1.65 V cm in a push-pull Mach-Zehnder interferometer structure.

doi:10.1063/1.4809818