Multimode interference coupler and method for the structural configuration thereof
AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorsReinhard Kunkel, Martin Schell, Inigo Molina-Fernandez, Gonzalo Wangümert Perez, Alejandro Ortega Monux
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Abstract
A multimode interference coupler includes at least one supply waveguide and at least one output waveguide, wherein the coupler has along its longitudinal extent in the direction of the supply waveguide at least one longitudinal section in which the refractive index has a locally oscillating profile in a direction running substantially at right angles to the direction of the supply waveguide. A method for the structural configuration of such a multimode interference coupler.
Claims20
A multimode interference coupler having
- at least one supply waveguide,
- at least one output waveguide, and
- at least one interference section which is coupled to the at least one supply waveguide and the at least one output waveguide, wherein
- the refractive index of said interference section has an oscillating profile in a direction running substantially perpendicular to the direction of the supply waveguide, and wherein
- the effective refractive index neff of the modes being able to propagate inside said interference section decreases in an approximately quadratic manner with the mode number.
A multimode interference coupler having
- at least one supply waveguide,
- at least one output waveguide, and
- at least one interference section which is coupled to the at least one supply waveguide and the at least one output waveguide, wherein
- the refractive index of said interference section has an oscillating profile in a direction running substantially perpendicular to the direction of the supply waveguide, wherein
- maximum and minimum values of the oscillating refractive index profile are variable, and
- wherein the maximum and minimum values increase from the center of the interference section towards its edge.
A method for the structural configuration of a multimode interference coupler, said coupler having
- at least one supply waveguide,
- at least one output waveguide, and
- at least one interference section which is coupled to the at least one supply waveguide and the at least one output waveguide, wherein
- the profile of the refractive index n(x) is determined by solving the following equation:
- n
- 2
-
- (
- x
- )
- =
- n
- 0
- 2
-
- (
- x
- )
- +
- ∑
- k
- =
- 0
- M
- -
- 1
-
- N
- k
- ·
- φ
- k
-
- (
- x
- )
- ,
- where x denotes the spatial coordinate in a direction running substantially perpendicular to the direction of the supply waveguide, n0(x) denotes the refractive index of a known multimode interference coupler, M is the mode number of the mode being able to propagate inside the at least one interference section, Nk are numerical coefficients and φk(x) denotes a set of base functions.
Dependencies are inferred from the claim text.