US 12,092,870 B2
Optical waveguide
Takashi Go, Musashino (JP); Kenya Suzuki, Musashino (JP); Keita Yamaguchi, Musashino (JP); and Ai Yanagihara, Musashino (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Appl. No. 17/782,799
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Dec. 11, 2019, PCT No. PCT/JP2019/048480
§ 371(c)(1), (2) Date Jun. 6, 2022,
PCT Pub. No. WO2021/117161, PCT Pub. Date Jun. 17, 2021.
Prior Publication US 2023/0032684 A1, Feb. 2, 2023
Int. Cl. G02B 6/122 (2006.01); G02B 6/12 (2006.01); G02B 6/125 (2006.01)
CPC G02B 6/125 (2013.01) [G02B 6/1228 (2013.01); G02B 2006/12035 (2013.01); G02B 2006/12147 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An optical waveguide comprising:
a first waveguide;
a second waveguide; and
a clothoid tapered waveguide bend inserted between the first waveguide and the second waveguide, wherein
a waveguide width of the clothoid tapered waveguide bend continuously changes from a first waveguide width at a connection point of the first waveguide to a second waveguide width at a connection point of the second waveguide, a curvature radius of the clothoid tapered waveguide bend continuously changes from a first curvature radius at the connection point of the first waveguide to a second curvature radius at the connection point of the second waveguide, the first waveguide width and the second waveguide width are different from each other, and the first curvature radius and the second curvature radius are different from each other, and wherein
at least one of the waveguide width and a curvature of the clothoid tapered waveguide bend changes in such a manner that a square of an absolute value of an overlap integral between normalized electric field distributions of front and rear basic propagation modes at a connection point of a minute section configuring the clothoid tapered waveguide bend and having a constant waveguide length becomes constant.