Lithium niobate waveguide having weak phase drift

A lithium niobate waveguide having weak phase drift, comprising:

• a lithium niobate layer,
• a metal electrode, and
• a substrate layer,
• wherein the lithium niobate layer comprises a lithium niobate central ridge and lithium niobate extension surfaces extending towards two sides of the lithium niobate central ridge,
• wherein a metal oxide layer is disposed on an upper surface of the lithium niobate central ridge, and
• wherein the substrate layer is located on a lower surface of the lithium niobate layer,
• wherein a thickness of the lithium niobate central ridge ranges from 0.2 to 3 μm, a thickness of each lithium niobate extension surface ranges from 0.1 to 1 μm, and a width of the lithium niobate central ridge ranges from 0.3 to 3 μm,
• wherein the metal oxide layer is disposed on upper surfaces of the lithium niobate extension surfaces and a side surface of the central ridge,
• wherein the metal electrode passes through partial or all of the metal oxide layers, and/or partial or all of the lithium niobate extension surfaces, and/or partial or all of the lower substrate layer to be connected to a surface of a lowermost layer that is passed through.