| CPC G02F 1/035 (2013.01) [G02F 1/212 (2021.01)] | 10 Claims |
|
1. An optical modulator comprising:
a rib waveguide that is a thin-film lithium niobate (LN) crystal;
a buffer layer that is laminated on the rib waveguide;
a signal electrode that is adjacent to the rib waveguide and inputs an electric signal to the rib waveguide; and
a ground electrode that is adjacent to the rib waveguide and outputs the electric signal from the rib waveguide, wherein
the buffer layer includes
a thick-film part that is laminated on a rib of the rib waveguide; and
thin-film parts that are laminated on slabs of the rib waveguide, the slabs being located on both sides of the rib, and that have smaller thicknesses than a thickness of the thick-film part,
the thick-film part includes
a first thick-film part that covers the rib; and
second thick-film parts that cover side wall surfaces of the rib, and cover parts of the slabs at sides of the rib, and
a second thick-film part of the second thick-film parts includes
a first stepped portion that is separated from one side wall surface at a side of the signal electrode of the side wall surfaces of the rib; and
a second stepped portion that is separated from other side wall surface at a side of a ground electrode of the side wall surfaces of the rib.
|