US 12,153,295 B2
Optical waveguide element, and optical modulation device and optical transmission device using the same
Masayuki Motoya, Tokyo (JP); and Toshio Kataoka, Tokyo (JP)
Assigned to SUMITOMO OSAKA CEMENT CO., LTD., Tokyo (JP)
Filed by SUMITOMO OSAKA CEMENT CO., LTD., Tokyo (JP)
Filed on Sep. 27, 2022, as Appl. No. 17/954,304.
Claims priority of application No. 2021-162200 (JP), filed on Sep. 30, 2021.
Prior Publication US 2023/0096004 A1, Mar. 30, 2023
Int. Cl. G02F 1/035 (2006.01); G02F 1/025 (2006.01)
CPC G02F 1/035 (2013.01) [G02F 1/025 (2013.01); G02F 2201/121 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An optical waveguide element comprising:
a substrate having an electro-optic effect;
an optical waveguide formed in the substrate; and
a control electrode arranged on the substrate to modulate a light wave propagating through the optical waveguide,
wherein the control electrode comprises a signal electrode and a ground electrode,
the signal electrode and the ground electrode are arranged along a modulation effect portion of the optical waveguide that performs modulation,
a shape of a bottom surface of the ground electrode facing the substrate, a slit separating the ground electrode into a first ground electrode close to the signal electrode and a second ground electrode far from the signal electrode is formed in a range corresponding to the modulation effect portion, and
a width of the slit in a direction perpendicular to an extending direction of the modulation effect portion is 40 μm or more,
a shape of the first ground electrode has an L-shaped multi-step structure in which a lower portion is closer to the signal electrode than an upper portion, and
a width of the lower portion protruding toward a signal electrode side more than the upper portion in a direction perpendicular to an extending direction of the modulation effect portion is set to a range of 20 to 70% of a width of the signal electrode.