US Patent 11402581 Mode converter

A mode converter for converting mode of propagating light is provided. The mode converter includes: a mode order conversion unit that includes an input-side first rib unit, an output-side first rib unit that extends along the input-side first rib unit, and a first slab unit arranged between the input-side first rib unit and the output-side first rib unit; and a rib channel conversion unit that includes an output-side second rib unit that is in contact with the output-side first rib unit, a second slab unit that is in contact with the first slab unit and a side surface of the output-side second rib unit, and a third slab unit that is in contact with another side surface of the output-side second rib unit.