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CN-116194811-B - Multi-core optical fiber

CN116194811BCN 116194811 BCN116194811 BCN 116194811BCN-116194811-B

Abstract

Multi-core optical fibers having low bending losses, low cross-talk and large mode field diameters. In some embodiments, a round multi-core optical fiber includes a glass matrix, at least 3 cores disposed in the glass matrix, wherein any two cores have a core center-to-core center spacing of less than 29 microns, and a plurality of depressed layers disposed between the corresponding cores and the glass matrix, each depressed layer having an outer radius of less than or equal to 14 microns and a depressed volume of greater than 50% Δmicrometer 2 , wherein the optical fiber has a mode field diameter of greater than about 8.2 microns at 1310nm, and wherein the optical fiber has an outer diameter of less than about 130 microns.

Inventors

  • K.W. Bennett
  • S.R. Buckham
  • LI MINGJUN
  • P. Tanden

Assignees

  • 康宁股份有限公司

Dates

Publication Date
20260505
Application Date
20210721
Priority Date
20200722

Claims (15)

  1. 1. A circular multi-core optical fiber, comprising: a glass substrate having a front face, a rear face, a length, a refractive index n 20 , and a central axis; at least 3 cores disposed in a glass matrix, each core having a center disposed along at least one diameter of the glass matrix, and wherein any two adjacent cores have a core center-to-core center spacing of less than 29 microns, wherein the core locations are located between the front and back end faces substantially parallel to the central axis and have respective refractive indices n 50 , wherein n 50 > n 20 , wherein each core and glass matrix define a waveguide, and A plurality of depressed layers, wherein each depressed layer is positioned between a corresponding core and a glass matrix, each depressed layer having an outer radius of less than or equal to 14 microns and a depressed volume of greater than 50% Δmicrons 2 ; Wherein the optical fiber has a mode field diameter at 1310 nm of greater than about 8.2 microns, Wherein the optical fiber has an outer diameter of less than about 130 microns, and Wherein the optical fiber further comprises an inner cladding region surrounding and directly contacting the core, the inner cladding region being formed of silica-based glass substantially free of dopants.
  2. 2. The optical fiber of claim 1, wherein the optical fiber comprises 4 cores, and wherein a center of each core is disposed along the first diameter of the glass matrix.
  3. 3. The optical fiber of claim 1, wherein the optical fiber comprises 5 cores, and wherein centers of the first and second cores are disposed along a first diameter of the glass matrix, and wherein centers of the third and fourth cores are disposed along a second diameter of the glass matrix that perpendicularly intersects the first diameter, and wherein centers of the fifth cores are located at intersections of the first and second diameters.
  4. 4. The optical fiber of claim 1, wherein the optical fiber has a diameter of about 125 microns.
  5. 5. The optical fiber of claim 1, wherein the plurality of cores is at least 4 cores.
  6. 6. The optical fiber of claim 1, wherein the plurality of cores is at least 8 cores.
  7. 7. The optical fiber of claim 1, wherein each optical fiber has a diameter of about 5 microns to about 27 microns.
  8. 8. The optical fiber of claim 1, wherein the optical fiber has a mode field diameter at 1310 nm that is greater than 8.5 microns.
  9. 9. The optical fiber of claim 1, wherein each recessed layer has an outer diameter of less than or equal to about 13 microns.
  10. 10. The optical fiber of claim 1, wherein the recess volume is greater than 55% microns 2 .
  11. 11. The optical fiber of claim 1, wherein the distance from the edge of the core to the edge of the glass matrix is 4 microns or less.
  12. 12. The optical fiber of claim 1, wherein the optical fiber has a crosstalk of less than about-30 dB.
  13. 13. The optical fiber of claim 1, wherein the difference in loss at 1310 nm between any two cores in the glass matrix is less than about 0.1 dB/km.
  14. 14. The optical fiber of claim 1, wherein the maximum loss per core in the glass matrix at 1310 nm is about 0.32 dB/km to about 0.45 dB/km.
  15. 15. The optical fiber of claim 1, wherein the difference in mode field diameter at 1310 nm between any two cores in the glass matrix is less than 0.3 microns.

Description

Multi-core optical fiber Cross reference to related applications The present application claims priority from U.S. patent application serial No. 63/054,941, filed on even 22-day 7 in 2020, in accordance with 35u.s.c. ≡119, the contents of which are hereby incorporated by reference in their entirety. Technical Field The present disclosure relates to multi-core optical fibers, and in particular, to multi-core optical fibers having low bending losses, low cross-talk, and large mode field diameters. Background A multi-core optical fiber is an optical fiber having multiple cores embedded in a cladding matrix. Multi-core optical fibers are attractive for many applications, including their use to increase fiber density to overcome cable size limitations and pipe congestion problems in passive optical network ("PON") systems. It is also attractive to use them for high speed optical interconnects, where there is a need to increase fiber density to achieve compact high fiber count connectors. For high performance of multi-core fibers, it is necessary to have low loss, low bending loss, low crosstalk, and large mode field, well matched to standard single mode fibers. Accordingly, the inventors have developed improved multi-core optical fibers with low bending losses, low cross-talk, and large mode field diameters. Disclosure of Invention In embodiment 1 disclosed herein, a circular multi-core optical fiber comprises a glass matrix having a front end face, a back end face, a length, a refractive index n 20, and a central axis, at least 3 cores disposed in the glass matrix, each core having a center disposed along at least one diameter of the glass matrix, and wherein any two cores have a core center-to-core center spacing of less than 29 microns, wherein the core positions are located substantially parallel to the central axis between the front and back end faces and have respective refractive indices n 50, wherein n 50>n20, wherein each core and the glass matrix define a waveguide, and a plurality of depressed layers, wherein each depressed layer is positioned between the corresponding core and the glass matrix, each depressed layer has an outer radius of less than or equal to 14 microns and a depressed volume of greater than 50% of Δmicron 2, wherein the optical fiber has a mode field diameter of greater than about 8.2 microns at 1310nm, and wherein the optical fiber has an outer diameter of less than about 130 microns. Embodiment 2 of the present disclosure may include embodiment 1, wherein the optical fiber comprises 4 cores, and wherein a center of each core is disposed along a first diameter of the glass matrix. Embodiment 3 of the present disclosure may include embodiment 1, wherein the optical fiber comprises 5 cores, and wherein centers of the first and second cores are disposed along a first diameter of the glass matrix, and wherein centers of the third and fourth cores are disposed along a second diameter of the glass matrix that perpendicularly intersects the first diameter, and wherein a center of the fifth core is located at an intersection of the first diameter and the second diameter. Embodiment 4 of the present disclosure may include embodiments 1 to 3, wherein the optical fiber has a diameter of about 125 microns. Embodiment 5 of the present disclosure may include embodiments 1 to 4, wherein the plurality of cores is at least 4 cores. Embodiment 6 of the present disclosure may include embodiments 1 to 4, wherein the plurality of cores is at least 8 cores. Embodiment 7 of the present disclosure may include embodiments 1 to 6, wherein each core has a diameter of about 5 microns to about 27 microns. Embodiment 8 of the present disclosure may include embodiments 1 to 7, wherein the optical fiber has a mode field diameter at 1310nm of greater than 8.5 microns. Embodiment 9 of the present disclosure may include embodiments 1 to 7, wherein the optical fiber has a mode field diameter at 1310nm of greater than 8.6 microns. Embodiment 10 of the present disclosure may include embodiments 1 to 9, wherein each recessed layer has an outer radius of less than or equal to about 13 microns. Embodiment 11 of the present disclosure may include embodiments 1 to 9, wherein each recessed layer has an outer radius of less than or equal to about 12.5 microns. Embodiment 12 of the disclosure may include embodiments 1 to 11, wherein the recess volume is greater than 55% Δmicron 2. Embodiment 13 of the present disclosure may include embodiments 1 to 11, wherein the recess volume is greater than 60% Δmicron 2. Embodiment 14 of the present disclosure may include embodiments 1 to 11, wherein the recess volume is greater than 65% Δmicrometer 2. Embodiment 15 of the present disclosure may include embodiments 1 to 14, wherein the distance from the edge of the core to the edge of the glass matrix is 4 microns or less. Embodiment 16 of the disclosure may include embodiments 1 through 14, wherein the distance from the edge of the core t