Flexible optical-fiber ribbon

1. An optical-fiber ribbon, comprising:

(i) a plurality of respectively adjacent optical fibers extending in a longitudinal direction and arranged in parallel to form an optical-fiber assembly, wherein each optical fiber includes, from its center to its periphery, a glass core, a glass cladding, a primary coating, and an outermost secondary coating comprising a cured first curable resin; and

(ii) a plurality of successive elongated rectilinear beads comprising a cured second curable resin arranged lengthwise along the optical-fiber assembly, wherein the beads are configured to form elongated bonds between adjacent optical fibers in the optical-fiber assembly;

wherein the cured second curable resin forming the beads has elongation at break of at least 150 percent as measured via ASTM D638-14;

wherein the cured second curable resin forming the beads has Young's modulus of between 1 MPa and 50 MPa as measured via ASTM D638-14; and

wherein, along at least a portion of the optical-fiber ribbon that includes successive elongated rectilinear beads, the beads are configured to fail internally at a load that is less than the load that would otherwise damage the optical fiber's primary coating and/or the optical fiber's outermost secondary coating during optical-fiber breakout.

2. The optical-fiber ribbon according to claim 1 , wherein the cured second curable resin forming the beads has elongation at break between 200 percent and 300 percent as measured via ASTM D638-14.

3. The optical-fiber ribbon according to claim 1 , wherein the cured second curable resin forming the beads has Young's modulus of between 15 MPa and 40 MPa as measured via ASTM D638-14.

4. The optical-fiber ribbon according to claim 1 , wherein the cured second curable resin forming the beads has stress at break between 20 MPa and 150 MPa as measured via ASTM D638-14.

5. The optical-fiber ribbon according to claim 1 , wherein the cured second curable resin forming the beads has intrinsic toughness of 20 mJ/mm 3 or less as measured via ASTM D638-14.

6. The optical-fiber ribbon according to claim 1 , wherein, as measured by a T-peel test, the force required to separate one optical fiber from the optical-fiber ribbon is between 0.01 N and 0.2 N.

7. The optical-fiber ribbon according to claim 1 , wherein, as measured by a T-peel test, the energy to break the bonds between each adjacent optical fiber's outermost secondary coating comprising the cured first curable resin and the corresponding bead comprising the cured second curable resin is 0.4 millijoule or less.

8. The optical-fiber ribbon according to claim 1 , wherein, as measured by a T-peel test, the force required to separate one 250-micron optical fiber from the optical-fiber ribbon is between 0.02 N and 0.15 N.

9. The optical-fiber ribbon according to claim 1 , wherein, as measured by a T-peel test, the force required to separate one 200-micron optical fiber from the optical-fiber ribbon is between 0.015 N and 0.1 N.

10. The optical-fiber ribbon according to claim 1 , wherein each elongated bond between adjacent optical fibers in the optical-fiber assembly chemically couples each adjacent optical fiber's cured first curable resin and the corresponding bead's cured second curable resin.

11. The optical-fiber ribbon according to claim 1 , wherein:

a first elongated rectilinear bead comprising a cured second curable resin is configured to form a first elongated bond connecting a first pair of adjacent optical fibers; and

a second elongated rectilinear bead comprising a cured second curable resin is configured to form a second elongated bond connecting a second pair of adjacent optical fibers, wherein at least one optical fiber of the second pair of adjacent optical fibers differs from the optical fibers of the first pair of adjacent optical fibers.

12. An optical-fiber-cable unit comprising one or more optical-fiber ribbons according to claim 1 .

13. An optical-fiber ribbon, comprising:

(i) a plurality of respectively adjacent optical fibers extending in a longitudinal direction and arranged in parallel to form an optical-fiber assembly, wherein each optical fiber includes, from its center to its periphery, a glass core, a glass cladding, a primary coating, a secondary coating, and an outermost ink layer comprising a cured first curable resin; and

(ii) a plurality of successive elongated rectilinear beads comprising a cured second curable resin arranged lengthwise along the optical-fiber assembly, wherein the beads are configured to form elongated bonds between adjacent optical fibers in the optical-fiber assembly;

wherein the cured second curable resin forming the beads has elongation at break of at least 150 percent as measured via ASTM D638-14;

wherein the cured second curable resin forming the beads has Young's modulus of between 1 MPa and 50 MPa as measured via ASTM D638-14; and

wherein, along at least a portion of the optical-fiber ribbon that includes successive elongated rectilinear beads, the beads are configured to fail internally at a load that is less than the load that would otherwise damage the optical fiber's primary coating, the optical fiber's secondary coating, and/or the optical fiber's outermost ink layer during optical-fiber breakout.

14. The optical-fiber ribbon according to claim 13 , wherein the cured second curable resin forming the beads has elongation at break between 200 percent and 300 percent as measured via ASTM D638-14.

15. The optical-fiber ribbon according to claim 13 , wherein the cured second curable resin forming the beads has Young's modulus of between 15 MPa and 40 MPa as measured via ASTM D638-14.

16. The optical-fiber ribbon according to claim 13 , wherein the cured second curable resin forming the beads has stress at break between 20 MPa and 150 MPa as measured via ASTM D638-14.

17. The optical-fiber ribbon according to claim 13 , wherein the cured second curable resin forming the beads has intrinsic toughness of 20 mJ/mm 3 or less as measured via ASTM D638-14.

18. The optical-fiber ribbon according to claim 13 , wherein, as measured by a T-peel test, the force required to separate one optical fiber from the optical-fiber ribbon is between 0.01 N and 0.2 N.

19. The optical-fiber ribbon according to claim 13 , wherein, as measured by a T-peel test, the energy to break the bonds between each adjacent optical fiber's outermost ink layer comprising the cured first curable resin and the corresponding bead comprising the cured second curable resin is 0.4 millijoule or less.

20. The optical-fiber ribbon according to claim 13 , wherein, as measured by a T-peel test, the force required to separate one 250-micron optical fiber from the optical-fiber ribbon is between 0.02 N and 0.15 N.

21. The optical-fiber ribbon according to claim 13 , wherein, as measured by a T-peel test, the force required to separate one 200-micron optical fiber from the optical-fiber ribbon is between 0.015 N and 0.1 N.

22. The optical-fiber ribbon according to claim 13 , wherein each elongated bond between adjacent optical fibers in the optical-fiber assembly chemically couples each adjacent optical fiber's cured first curable resin and the corresponding bead's cured second curable resin.

23. The optical-fiber ribbon according to claim 13 , wherein:

a first elongated rectilinear bead comprising a cured second curable resin is configured to form a first elongated bond connecting a first pair of adjacent optical fibers; and

a second elongated rectilinear bead comprising a cured second curable resin is configured to form a second elongated bond connecting a second pair of adjacent optical fibers, wherein at least one optical fiber of the second pair of adjacent optical fibers differs from the optical fibers of the first pair of adjacent optical fibers.

24. An optical-fiber-cable unit comprising one or more optical-fiber ribbons according to claim 13 .