Patent ID: 11921320
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical circuit comprising:
a first waveguide configured to guide light in an N-th order mode (N is an integer satisfying N≥0);
a second waveguide, having a larger width than the first waveguide, configured to guide light in an M-th order mode (M is an integer satisfying M>N); and
a third waveguide configured to guide light in the N-th order mode, the third waveguide having a width that is the same as the width of the first waveguide,
wherein the first waveguide, the second waveguide, and the third waveguide are placed side by side in this order in a manner that the first waveguide, the second waveguide, and the third waveguide do not contact each other,
wherein the second waveguide includes at least a first curved portion in a curve shape curved toward the first waveguide while maintaining a combination of waveguide widths satisfying a mode conversion condition,
wherein the second waveguide and the third waveguide include, in a posterior stage of the first curved portion, a second curved portion in a curved shape curved toward the third waveguide while maintaining a combination of waveguide widths satisfying the mode conversion condition, and
wherein the first and third waveguides curve with the second waveguide.