Anti-resonant hollow-core fibers featuring support structures
An optical fiber may include a cladding structure extending along a fiber length providing a hollow interior fiber region, and anti-resonant (AR) elements formed as walled structures with walls extending along the fiber length. At least one of the AR elements surrounds an interior region and further includes one or more support structures in the interior region and formed as at least a portion of at least one of the walls, where the one or more support structures have a non-uniform thickness profile, and where the plurality AR elements is configured to guide light along the fiber length in a central portion of the hollow interior fiber region based on optical anti-resonance.
1 . An anti-resonant hollow-core optical fiber (AR-HCF) comprising:
one or more cladding structures extending along a length of the AR-HCF providing a hollow interior fiber region;
a first set of nested anti-resonant (AR) elements formed as a first distribution of two or more walled structures with walls extending along the length of the AR-HCF, wherein the first set of nested AR elements is distributed around and exclusively in contact with the one or more cladding structures, wherein all constituent AR elements of a particular one of first set of nested AR elements are in contact at a first contact point; and
a second set of nested AR elements formed as a second distribution of two or more walled structures extending along the length of the AR-HCF, wherein the second set of nested AR elements is distributed around and exclusively in contact with the one or more cladding structures and interleaved with the first set of nested AR elements, wherein all constituent AR elements of a particular one of the second set of nested AR elements are in contact at a second contact point, wherein an outer dimension of the first set of nested AR elements is larger than an outer dimension of the second set of nested AR elements, wherein the first set of nested AR elements and the second set of nested AR elements each include at least five sets of nested AR elements, wherein the second set of nested AR elements are in an alternating arrangement with the first set of nested AR elements to supplement confinement of light in the hollow interior fiber region by the first set of nested AR elements through optical antiresonance.
2 . The AR-HCF of claim 1 , wherein a quantity of the constituent AR elements in each of the first set of nested AR elements is different than a quantity of the constituent AR elements in each of the second set of nested AR elements.
3 . The AR-HCF of claim 1 , wherein the one or more cladding structures is formed as a tube, wherein each of the first set of nested AR elements contacts the tube at the first contact point, wherein each of the second set of nested AR elements contacts the tube at the second contact point.
4 . The AR-HCF of claim 1 , wherein the one or more cladding structures comprise a tube and one or more additional cladding elements located between the tube and at least one of the first set of nested AR elements or at least one of the second set of nested AR elements.
5 . The AR-HCF of claim 1 , further comprising:
a third set of AR elements formed as walled structures extending along the length of the AR-HCF.
6 . The AR-HCF of claim 1 , wherein at least one of the first set of nested AR elements comprises:
a first nested AR element; and
a second nested AR element located within an interior region of the first nested AR element bounded at least in part by the walls of the first nested AR element.
7 . The AR-HCF of claim 6 , wherein the first nested AR element is formed as a wall extending along the length of the AR-HCF and located entirely within the hollow interior fiber region, wherein the wall of the first nested AR element, in a cross-sectional plane orthogonal to the length of the AR-HCF, fully surrounds an interior region and further has a non-uniform thickness profile between the interior region and an outer perimeter of the first nested AR element, wherein the non-uniform thickness profile forms one or more support structures with solid shapes in the cross-sectional plane, wherein the second nested AR element is exclusively connected to the one or more support structures.
8 . The AR-HCF of claim 7 , wherein the one or more support structures comprise:
one or more slab support structures.
9 . The AR-HCF of claim 7 , wherein a fill factor defined as a ratio of an area of the walls of the first nested AR element in the cross-sectional plane to an area of the first nested AR element bounded by an outer face in the cross-sectional plane is at least 20%.
10 . The AR-HCF of claim 7 , wherein the one or more support structures include at least one of a notch or a groove to form two contact points with the second nested AR element.
11 . The AR-HCF of claim 7 , wherein at least one of the one or more support structures are porous.
12 . The AR-HCF of claim 6 , wherein at least one of the second set of nested AR elements comprises:
a third nested AR element; and
a fourth nested AR element located within an interior region of the third nested AR element bounded at least in part by the walls of the third nested AR element.
13 . The AR-HCF of claim 12 , wherein the fourth nested AR element is connected to one or more additional support structures, wherein the one or more additional support structures are formed as at least a portion of at least one of the walls of the third nested AR element, wherein the one or more additional support structures have a non-uniform thickness profile.
14 . The AR-HCF of claim 6 , wherein the third set of AR elements includes a set of non-nested AR elements.
15 . The AR-HCF of claim 6 , wherein the third set of AR elements includes a set of nested AR elements.
16 . The AR-HCF of claim 1 , wherein the second set of nested AR elements supplements the confinement of the light in the hollow interior fiber region by the first set of nested AR elements.
17 . The AR-HCF of claim 1 , wherein the second set of nested AR elements aids in the confinement of the light in the hollow interior fiber region when the AR-HCF is bent.
18 . The AR-HCF of claim 1 , wherein the second set of nested AR elements improves at least one of microbending loss or macrobending loss by at least 10 percent relative to an AR-HCF including the first set of nested AR elements and excluding the second set of nested AR elements.
19 . The AR-HCF of claim 1 , wherein the first set of nested AR elements and the second set of nested AR elements are symmetrically distributed to provide polarization-insensitive guiding of the light in the hollow interior fiber region.
20 . A method comprising:
fabricating a nested-element preform by:
fabricating a cladding preform including a hollow interior preform region;
fabricating a first set of nested anti-resonant (AR) preform elements distributed around walls of the hollow interior preform region; and
fabricating a second set of nested AR preform elements distributed around the walls of the hollow interior preform region and interleaved with the first set of nested AR preform elements, wherein the first set of nested AR elements and the second set of nested AR elements each include at least five sets of nested AR elements; and
drawing the nested-element preform into an AR hollow-core optical fiber (AR-HCF), wherein the AR-HCF comprises:
a cladding structure associated with the cladding preform, wherein the cladding structure extends along a length of the AR-HCF providing a hollow interior fiber region;
a first set of nested anti-resonant (AR) elements associated with the first set of nested AR preform elements, wherein the first set of nested AR elements are formed as walled structures with walls extending along the length of the AR-HCF, wherein the first set of nested AR elements is distributed around and in contact with a wall of the hollow interior fiber region; and
a second set of nested AR elements associated with the second set of nested AR preform elements, wherein the second set of nested AR elements are formed as walled structures extending along the length of the AR-HCF, wherein the second set of nested AR elements is distributed around and in contact with the wall of the hollow interior fiber region and interleaved with the first set of nested AR elements, wherein an outer dimension of the first set of nested AR elements is larger than an outer dimension of the second set of nested AR elements, wherein the second set of nested AR elements are in an alternating arrangement with the first set of nested AR elements to supplement confinement of light in the hollow interior fiber region by the first set of nested AR elements through optical antiresonance.
21 . The method of claim 20 , wherein the first set of AR preform elements includes one or more sets of nested AR preform elements, wherein at least one of the one or more sets of nested AR preform elements comprises a first nested AR preform element and a second nested AR preform element located within an interior region of the first nested AR element bounded at least in part by the walls of the first AR element, wherein the first set of AR elements includes one or more sets of nested AR elements associated with the one or more sets of nested AR preform elements.
22 . The method of claim 21 , wherein the second nested AR preform element is connected to one or more support structure preform elements, wherein the second nested AR element is connected to one or more support structures, wherein the one or more support structures are formed as at least a portion of at least one of the walls of the first nested AR element, wherein the one or more support structures have a non-uniform thickness profile.