Optical phase shifter, optical switch and 90 degrees optical hybrid
AssigneeNTT, Inc.
InventorsTakashi Go, Yuichiro Ikuma, Kenya Suzuki, Keita Yamaguchi, Ai Yanagihara
Life of this patent
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Abstract
An optical phase shifter in which a phase shift amount is kept constant in a wide wavelength region is provided. One aspect is the optical phase shifter constituting of two waveguides of a basic width, and configured so that two lights propagating through each waveguide have a phase difference, including a different type waveguide arranged in at least one of the two waveguides and having a waveguide width different from the basic width, and a configuration of the different type waveguide and a parameter of the two waveguides and different type waveguide are optimized.
Claims13
An optical phase shifter including two waveguides having a basic width W0 and configured such that two light beams propagating through the respective two waveguides have a phase difference ξ, the two waveguides comprising:
- a first waveguide;
- and
- a second waveguide,
- wherein the first waveguide comprises:
- a waveguide having a basic width W0;
- and
- a first different type waveguide having a width W1 different from the basic width W0 and a length L1, and
- the second waveguide comprises a waveguide having the basic width W0,
- wherein the first waveguide and the second waveguide are different in length by a difference ΔL, and when an equivalent refractive index of a waveguide having a width w is defined as n(w), a propagation distance along a light propagation path in the first different type waveguide from a starting point of the first different type waveguide is defined as z1, and a width of the first different type waveguide at the propagation distance z1 is set to W(z1), in a phase difference Δφ,
- Δ
-
- ϕ
- =
- 2
-
- π
-
- n
-
- (
- W
- 0
- )
- ·
- Δ
-
- L
- +
- ∫
- 0
- L
- 1
- {
- n
-
- (
- W
-
- (
- z
- 1
- )
- )
- -
- n
-
- (
- W
- 0
- )
- }
- ·
- dz
- 1
- λ
- [
- Math
- .
- 1
- ]
- for a wavelength λ of a predetermined wavelength range, the length L1 and the difference ΔL are set so that
- ∫
- (
- Δϕ
- -
- ξ
- )
- 2
-
- d
-
- λ
- [
- Math
- .
- 2
- ]
- becomes minimum.
Dependencies are inferred from the claim text.