Fiber optic cables and assemblies for fiber toward the subscriber applications
View Patent ↗A fiber optic cable includes an optical fiber, strength components disposed on opposite sides of the optical fiber, and a polymeric cable jacket. The optical fiber includes a glass core, a glass cladding, and a polymer coating. The cable jacket surrounds the optical fiber and the strength components. Further, the cable jacket is tightly drawn onto the optical fiber, where excess fiber length of the optical fiber is such that positive strain is present in the optical fiber at room temperature (25° C.).
1. A fiber optic cable comprising:
an optical fiber comprising a glass core, a glass cladding, and a polymer coating;
strength components disposed on opposite sides of the optical fiber; and
a polymeric cable jacket, wherein the cable jacket surrounds the optical fiber and the strength components,
wherein the cable jacket is tightly drawn onto the optical fiber, and wherein excess fiber length of the optical fiber is such that positive strain is present in the optical fiber, and wherein the fiber strain at room temperature (25° C.) is in the range of 0.1 to 0.3%.
2. The fiber optic cable of claim 1 , wherein a cross-sectional area of the fiber optic cable is in the range of 8 to 22 square millimeters and the fiber optic cable has a cross-sectional width in the range of 3 to 6 millimeters.
3. The fiber optic cable of claim 2 , wherein the cable jacket is tightly drawn onto the optical fiber without bonding to the optical fiber such that the optical fiber has a pull out force of less than eight pounds.
4. The fiber optic cable of claim 2 , wherein the fiber optic cable has a weight of 19 kilograms or less per kilometer.
5. The fiber optic cable of claim 1 , wherein the cable jacket has a medial height disposed about the optical fiber and an end height disposed about at least a portion of the strength components, wherein the medial height is less than the end height, and wherein a ratio of the medial height to the end height is less than 0.95.
6. The fiber optic cable of claim 5 , wherein the ratio of the medial height to the end height is in the range of 0.6 to 0.9.
7. The fiber optic cable of claim 1 , wherein the optical fiber is a bend-resistant optical fiber, such that:
attenuation at a wavelength of 850 nanometers in the optical fiber increases less than 0.5 decibels when the optical fiber is wrapped one turn around a mandrel that is 10 millimeters in diameter, and
the attenuation at the 850 nanometers wavelength in the optical fiber increases less than 0.2 decibels when the optical fiber is wrapped one turn around a mandrel that is 20 millimeters in diameter.
8. The fiber optic cable of claim 7 , wherein the cladding of the optical fiber comprises annular portions, and wherein a first of the annular portions of the cladding has a lesser index of refraction than a second of the annular portions.
9. The fiber optic cable of claim 8 , wherein at least one of the annular portions of the cladding comprises doped glass.
10. The fiber optic cable of claim 7 , wherein the cable jacket is contacting and tightly drawn onto the optical fiber without bonding to the optical fiber.
11. The fiber optic cable of claim 7 , wherein a cross-sectional area of the fiber optic cable is in the range of 8 to 22 square millimeters and the fiber optic cable has a cross-sectional width in the range of 3 to 6 millimeters.
12. The fiber optic cable of claim 11 , wherein the fiber optic cable has a weight of 19 kilograms or less per kilometer.
13. The fiber optic cable of claim 7 , wherein the cable jacket has a medial height disposed about the optical fiber and an end height disposed about at least a portion of the strength components, and wherein the medial height is less than the end height.
14. The fiber optic cable of claim 1 , wherein the strength components comprise a first elongate strength component and a second strength component,
wherein the first strength component and the second strength component are disposed on opposite sides of the optical fiber from one another and are generally aligned along a common plane with the optical fiber, wherein spacing between inner surfaces of the first and second strength components is in the range of about 0.8 to 1.5 millimeters, with the inner surfaces a distance of between about 0.4 to 0.75 millimeters on either side of the center of the optical fiber, and wherein the first and second strength components are larger in cross-sectional size than the optical fiber, whereby the first and second strength components shoulder crushing forces applied to the cable and thereby reduce attenuation of the optical fiber due to the crushing forces.
15. The fiber optic cable of claim 14 , wherein the spacing between inner surfaces of the first and second strength components is in the range of 0.9 to 1.35 millimeters.
16. The fiber optic cable of claim 14 , wherein when the cable is subjected to a crush load of 80 newtons per millimeter, the optical fiber experiences a radial stress of less than 30 megapascals.
17. The fiber optic cable of claim 14 , wherein when the cable is subjected to a crush displacement of 0.4 millimeters, the optical fiber experiences a radial stress of less than 15 megapascals.
18. The fiber optic cable of claim 14 , wherein the first and second strength components are dielectric rods.
19. The fiber optic cable of claim 18 , wherein the cable jacket has a medial height disposed about the optical fiber and an end height disposed about the first strength component, and wherein the medial height is less than the end height.
20. The fiber optic cable of claim 14 , wherein the cable jacket is contacting and tightly drawn onto the optical fiber without bonding to the optical fiber.