An apparatus includes a lithium niobate (LN) layer, and a planar electro-optical modulator having at least one hybrid optical core segment formed of a portion of the LN layer and an optical guiding rib. The optical guiding rib may be located in a top silicon layer of a silicon photonics (SiP) chip, to which a thin-film LN chip is flip-chip mounted, and may be coupled to optical waveguide cores in a first silicon core layer of the SiP chip. One or more drive electrodes are disposed between a substrate of the SiP chip and the LN layer. In some embodiments hybrid optical core segments may include silicon nitride core segments and may form an MZM configured to be differentially or dual-differentially driven.