Optical hybrid-waveguide electro-optical modulator

An apparatus, comprising:

• a silicon substrate;
• a lithium niobate (LN) layer;
• a planar electro-optic Mach-Zehnder modulator extending along a main surface of the silicon substrate and comprising two optical waveguide arms connected to receive light in parallel from an optical splitter, and two pairs of traveling wave (TW) drive electrodes, each pair of TW drive electrodes disposed to modulate light in a respective one of the two optical waveguide arms;
• an electrical driver connected to provide differential drive signals to the two pairs of TW drive electrodes such that the two optical waveguide arms are driven in a push-pull manner, the electrical driver having differential outputs connected to the at least two TW drive electrodes;
• and
• wherein each of the two optical waveguide arms comprises a hybrid optical core segment located adjacent to a corresponding pair of the two pairs of TW drive electrodes, each hybrid optical core segment comprising a portion of the LN layer and an optical guiding rib located adjacent to and along the portion of the LN layer, each optical guiding rib being a silicon rib integral with the silicon substrate, wherein the LN layer has a thickness in a range from 400 nm to 800 nm.