US 12,184,338 B2 · Optical 90-degree hybrid

Abstract

An optical 90-degree hybrid includes two splitters, two combiners and four arm waveguides that connect output ports of the splitters and input ports of the combiners. Each of the splitters, the arm waveguides, and the combiners is a part of an optical waveguide. The optical waveguide is configured so that the phase error generated in the splitters due to wavelength change is suppressed by the phase error generated in the arm waveguides due to the wavelength change. The optical waveguide is further configured so that the phase error generated in the splitters due to deviation of a structure parameter from a certain value (e.g., design value) is suppressed by the phase error generated in the arm waveguides due to the deviation.

An optical 90-degree hybrid comprising:

a first splitter that has a first output port, and a second output port that is different from the first output port, the first splitter being a 2×2 multimode interferometer;
a second splitter that is different from the first splitter and that has a third output port, and a fourth output port that is different from the third output port, the second splitter being another 2×2 multimode interferometer;
a first combiner that has a first input port, and a second input port that is different from the first input port;
a second combiner that is different from the first combiner and that has a third input port, and a fourth input port that is different from the third input port;
a first arm waveguide that connects the first output port and the third input port;
a second arm waveguide that connects the second output port and the second input port;
a third arm waveguide that connects the third output port and the first input port;
and
a fourth arm waveguide that connects the fourth output port and the fourth input port, wherein
the first splitter splits a first light into a first split light and a second split light, outputs the first split light from the first output port, and outputs the second split light from the second output port,
the second splitter splits a second light into a third split light and a fourth split light, outputs the third split light from the third output port, and outputs the fourth split light from the fourth output port,
the first combiner combines the second split light that enters thereto via the second arm waveguide and the third split light that enters thereto via the third arm waveguide so as to generate a first interference light and a second interference light that is opposite in phase to the first interference light,
the second combiner combines the fourth split light that enters thereto via the fourth arm waveguide and the first split light that enters thereto via the first arm waveguide so as to generate a third interference light and a fourth interference light that is opposite in phase to the third interference light,
each of the first and second splitters, the first to fourth arm waveguides, and the first and second combiners is a part of an optical waveguide that has a core and a cladding that surrounds the core,
the first output port is a cross port to an input port to which the first light enters,
the second output port is a through port to the input port to which the first light enters,
the third output port is a cross port to an input port to which the second light enters,
the fourth output port is a through port to the input port to which the second light enters, and
the optical waveguide is configured to satisfy following Expressions (1) to (4),
∂
Φ
∂
λ
<
0
(
1
)
∂
Φ
∂
λ
>
0
(
2
)
=
(
k
+
2
)
×
π
/
2
+
2
⁢
m
⁢
π
(
3
)
Φ
=
(
Φ1
-
Φ4
)
-
(
Φ2
-
Φ3
)
(
4
)
where λ is a wavelength of the first light and the second light, X is deviation of width of the core, Φ1 is a phase imparted to the first split light by the first arm waveguide, Φ2 is a phase imparted to the second split light by the second arm waveguide, Φ3 is a phase imparted to the third split light by the third arm waveguide, Φ4 is a phase imparted to the fourth split light by the fourth arm waveguide, m is an integer, k is either +1 or −1, and a unit of phases is radian.

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Optical 90-degree hybrid

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Optical 90-degree hybrid

Life of this patent

Abstract

Claims4