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US 9,484,706 B1Granted
Tapered core fiber manufacturing methods
AssigneenLIGHT, Inc.
InventorsJoona Koponen, Laeticia Petit, Petteri Väinänen
Life of this patent
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Abstract
Tapered core fibers are produced using tapered core rods that can be etched or ground so that a fiber cladding has a constant diameter. The tapered core can be an actively doped core, or a passive core. One or more sleeving tubes can be collapsed onto a tapered core rod and exterior portions of the collapsed sleeving tubes can be ground to provide a constant cladding diameter in a fiber drawn from the preform.
Claims13
An optical fiber, comprising:
- a tapered core that extends along a propagation axis, wherein the tapered core is at least partially doped with a rare earth element;
- and
- an inner cladding that surrounds the core and extends along the propagation axis, wherein the tapered core and the inner cladding have respective cross-sectional areas ACORE, AINNER, and a ratio ACORE/AINNER varies along the propagation axis, wherein the tapered core and the inner cladding define a plurality of portions with few mode cores and a plurality of portions that define single mode waveguides, wherein the single mode waveguide portions and the few mode core portions are spatially separate and alternatingly disposed along the propagation axis, and wherein an outer edge of the inner cladding defines a constant cross-sectional area.
A method, comprising:
- situating a core rod having a tapered core in a cladding tube, wherein the tapered core is doped with an active dopant;
- and
- drawing the core rod and the cladding tube so as to form a few mode optical fiber having an inner cladding that surrounds a fiber core and extends along the propagation axis, wherein the tapered core and the inner cladding have respective cross-sectional areas ACORE, AINNER, and a ratio ACORE/AINNER varies along the propagation axis, wherein the fiber core has a plurality of portions with few mode cores and a plurality of single mode tapered portions, wherein the single mode tapered portions and the few mode core portions are spatially separate and alternatingly disposed along the propagation axis, and wherein an outer edge of the inner cladding defines a constant cross-sectional area.
An optical fiber, comprising:
- a tapered core that extends along a propagation axis, wherein the tapered core is at least partially doped with a rare earth element;
- and
- an inner cladding that surrounds the core and extends along the propagation axis, wherein the tapered core and the outer edge of the inner cladding define respective cross-sectional areas ACORE and AINNER having diameters d1 and d2, respectively, wherein d1 varies along the propagation axis and each of d1 and d2 varies periodically along the propagation axis over at least two periods, and wherein the tapered core and the inner cladding define a few mode core, and a portion of the tapered core defines a single mode waveguide.
Dependencies are inferred from the claim text.