Lithium niobate photonic devices having engineered lithium niobate, silicon dioxide, and electrode extension thickness

A subassembly, comprising:

• an optical modulator, the optical modulator including a waveguide and an electrode, the waveguide including a ridge including at least one optical material having an electro-optic effect and being configured to carry an optical signal, the optical material including lithium, the electrode including a channel region and plurality of extensions, the plurality of extensions residing between the channel region and the waveguide, the plurality of extensions being closer to a portion of the waveguide than the channel region is, each of the plurality of extensions including a connecting portion coupled to the channel region and a retrograde portion, the connecting portion being between the retrograde portion and the channel region, the retrograde portion having a first width and the connecting portion having a second width, the first width being greater than the second width, the first width being not more than one micrometer, the channel region of the electrode being configured to carry an electrode signal, the plurality of extensions being configured to increase an electric field due to the electrode signal at the waveguide, the electrode signal providing electro-optic modulation of the optical signal in a frequency range having a bandwidth of at least 10 GHz, the optical modulator being configured to reduce a velocity mismatch between the optical signal and the electrode signal;
• and
• a driver coupled to the optical modulator and configured to electrically drive the electrode;
• wherein a functionality of the optical modulator is tailored by configuring compositions, shapes, dimensions, placements, and/or orientations of the electrode and the plurality of extensions relative to a composition, cut, and/or cross-sectional profile of the waveguide.

A method, comprising:

• providing a waveguide for an optical device, the waveguide including a ridge including at least one optical material having an electro-optic effect and being configured to carry an optical signal;
• and
• providing an electrode including:
• providing a channel region;
• and
• providing a plurality of extensions protruding from the channel region, the plurality of extensions being closer to a portion of the waveguide than the channel region is, each of the plurality of extensions including a connecting portion coupled to the channel region and a retrograde portion, the connecting portion being between the retrograde portion and the channel region, the retrograde portion having a first width and the connecting portion having a second width, the first width being not more than one micrometer, the first width being greater than the second width, the electrode being configured to carry an electrode signal, the plurality of extensions being configured to increase an electric field due to the electric signal at the waveguide, the electrode signal providing electro-optic modulation of the optical signal in a frequency range having a bandwidth of at least 10 GHz;
• wherein the waveguide and the electrode are configured to reduce a velocity mismatch between the optical signal and the electrode signal;
• and
• wherein a functionality of the optical device is tailored by configuring compositions, shapes, dimensions, placements, and/or orientations of the electrode and the plurality of extensions relative to a composition, cut, and/or cross-sectional profile of the waveguide.