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US 9,753,222 B2Granted
Asymmetric optical fiber coupler
AssigneePolyvalor, Limited Partnership
InventorsNicolas Godbout, Caroline Boudoux, Wendy-Julie Madore, Simon Lemire-Renaud, Xavier Daxhelet, Mikael Leduc
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Abstract
There is described an optical fiber coupler in which at least one fiber is a multiple-clad fiber, containing a single-mode core supporting a single guiding mode and an inner multi-mode cladding guiding multiple modes. The multiple-clad fiber is fused with a second fiber of a different etendue to create an optical fiber coupler having an enhanced multi-mode signal transmission.
Claims24
An optical fiber coupler comprising:
- a first optical fiber having a first cross-talk portion located between a first end and a second end, and having a first single-mode core, at least one inner multi-mode cladding, and a first outer cladding, the first cross-talk portion having a first etendue;
- a second optical fiber having a second cross-talk portion located between a third end and a fourth end, the second cross-talk portion having a second etendue, the second etendue forming an etendue ratio differing from one relative to the first etendue;
- and
- a coupling region where the first cross-talk portion is optically coupled to the second cross-talk portion;
- wherein the etendue ratio is indicative of an extraction of more than 50% of a multi-mode signal from the at least one inner multi-mode cladding of the first optical fiber at the second end to the third end of the second optical fiber while maintaining a single-mode signal in the first single-mode core,
- wherein a first cross-sectional area of the at least one inner multi-mode cladding of the first optical fiber is different from a second cross-sectional area of the second optical fiber, and
- wherein an inner one of the at least one inner multi-mode cladding is tapered to form an inner single-mode cladding, such that a fundamental mode of the first single-mode core is adiabatically transformed into a fundamental mode of the inner single-mode cladding and the inner single-mode cladding is transformed into a single-mode guiding region.
4 more elements
An optical fiber coupler comprising:
- a first fiber having a first end, a second end, a first middle portion therebetween and a first cross-section, and having a first core supporting a single guiding mode and a first inner cladding larger than the first core for guiding multiple modes;
- a second fiber having a third end, a fourth end, and a second middle portion therebetween, and having a second cross-section different from the first cross-section in at least one of structure and dimension, whereby a dimension of the second cross-section is different than a dimension of the first cross-section;
- and
- a fused region composed of the first middle portion fused to the second middle portion for a single mode signal to remain in the first core of the first fiber from the first end to the second end, and for more than half (50%) of a multi-mode signal in the first inner cladding of the first fiber to be extracted to the second fiber;
- wherein the first fiber is a pre-tapered double-clad fiber and a fundamental mode of the first core is adiabatically transformed into a fundamental mode of a reduced first inner cladding by pre-tapering of the first fiber, and the reduced first inner cladding is transformed into a single-mode guiding region.
2 more elements
A method for making an optical coupler comprising:
- providing a first optical fiber having a first end, a second end, a first cross-talk portion therebetween, and having a first core, at least one inner cladding, and a first outer cladding, the first cross-talk portion having a first etendue;
- providing a second optical fiber having a third end, a fourth end, a second cross-talk portion therebetween, the second cross-talk portion having a second etendue, the second etendue differing from the first etendue;
- tapering at least the first cross-talk portion;
- positioning at least a certain section of the first cross-talk portion of the first optical fiber in contact and along a certain section of the second cross-talk portion of the second optical fiber;
- and
- providing heat to both certain sections of the first and second cross-talk portions in a manner forming a fused region;
- wherein the fused region allows a single-mode signal to remain in the first core between the first end and the second end of the first optical fiber, and for more than half of a multi-mode signal in one of the at least one inner cladding of the first optical fiber to be extracted to the second optical fiber.
4 more elements
Dependencies are inferred from the claim text.