US 12,282,191 B2
Optical circuit element
Hiroki Hara, Tokyo (JP); Takashi Kikukawa, Tokyo (JP); and Atsushi Shimura, Tokyo (JP)
Assigned to TDK CORPORATION, Tokyo (JP)
Appl. No. 17/924,522
Filed by TDK CORPORATION, Tokyo (JP)
PCT Filed Aug. 19, 2021, PCT No. PCT/JP2021/030371
§ 371(c)(1), (2) Date Nov. 10, 2022,
PCT Pub. No. WO2022/070659, PCT Pub. Date Apr. 7, 2022.
Claims priority of application No. 2020-167655 (JP), filed on Oct. 2, 2020.
Prior Publication US 2023/0228941 A1, Jul. 20, 2023
Int. Cl. G02B 6/125 (2006.01); G02B 6/12 (2006.01)
CPC G02B 6/125 (2013.01) [G02B 2006/1204 (2013.01); G02B 2006/12061 (2013.01); G02B 2006/12097 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An optical circuit element comprising:
a substrate;
an optical waveguide layer that is formed on one surface of the substrate; and
a protective layer that is overlaid on the optical waveguide layer,
wherein the optical waveguide layer has an optical waveguide configured for light to be propagated therethrough,
wherein three or more groove portions, each of which reaches to a position deeper than the one surface of the substrate from a surface of the protective layer toward the substrate, are formed in a manner of extending substantially parallel to each other,
the optical circuit element further comprises a light absorption layer that covers at least a bottom surface and a side surface of at least one of the groove portions,
the groove portions are formed separated from each other along the one surface of the substrate, ends of the groove portions being aligned on a virtual straight line as viewed in a direction perpendicular to a lamination direction,
the groove portions are formed such that a gap between arbitrary adjacent groove portions among the groove portions differs from a gap between different arbitrary adjacent groove portions among the groove portions,
a gap d between the one surface of the substrate and a bottom surface of each of the groove portions is equal to or larger than half a wavelength of the light to be propagated through the optical waveguide, and
the optical waveguide layer includes lithium niobate.