Optical modulation element

Abstract

To provide an optical modulation element whereby reduced drive voltage and suppression of DC drift can be obtained at the same time. An optical modulation element includes: a substrate; and an optical waveguide formed of an electrooptic material film formed on the substrate and having a ridge part which is a protruding portion, and a slab part having a smaller film thickness than the ridge part 11r. The optical waveguide includes a first waveguide part having a first ridge width and a first slab film thickness and to which an RF signal is applied, and a second waveguide part having a second ridge width and a second slab film thickness different from the first slab film thickness and to which a DC bias is applied.

Dependencies are inferred from the claim text.