US 12,032,231 B2
Optical signal processing apparatus and manufacturing method thereof
Keita Yamaguchi, Musashino (JP); Ai Yanagihara, Musashino (JP); Kenya Suzuki, Musashino (JP); Takashi Go, Musashino (JP); and Osamu Moriwaki, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/311,959
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Dec. 24, 2019, PCT No. PCT/JP2019/050556
§ 371(c)(1), (2) Date Jun. 8, 2021,
PCT Pub. No. WO2020/138053, PCT Pub. Date Jul. 2, 2020.
Claims priority of application No. 2018-243258 (JP), filed on Dec. 26, 2018.
Prior Publication US 2022/0066244 A1, Mar. 3, 2022
Int. Cl. G02F 1/01 (2006.01); B29D 11/00 (2006.01); G02F 1/21 (2006.01); G02F 1/225 (2006.01)
CPC G02F 1/0147 (2013.01) [B29D 11/00932 (2013.01); G02F 1/212 (2021.01); G02F 1/2257 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An optical signal processing device formed as a planar optical circuit comprising:
an optical waveguide formed on a silicon substrate, the optical waveguide comprising:
a phase modulation element that employs a thermo-optical effect;
a first silica thin film that is provided between a core of the optical waveguide and the silicon substrate;
a second silica thin film that is provided between the core of the optical waveguide and the silicon substrate;
a silicon laver that extends an entire width of an interface between the first silica thin film and the second silica thin film;
a first insulating groove; and
a second insulating groove,
wherein at least one of the first and second silica thin films was formed by thermal oxidation,
wherein the core of the optical waveguide is stacked on top the first silica thin film, the first silica thin film is stacked on top the silicon layer, the silicon layer is stacked on top of the second silica thin film, and the second silica thin film is stacked on top of the silicon substrate,
wherein a first width of the first silica thin film, the silicon layer, and the second silica thin laver are the same,
wherein a second width of the first and second insulating grooves is the same, and
wherein the second width of the first and second insulating grooves is larger than the first width of the first silica thin film, the silicon layer, and the second silica thin layer.