Optical fibers with improved resistance to ingressing molecules
An optical fiber includes a glass fiber having a glass core and a cladding which contains voids spaced apart from the core. The voids act as trapping sites for ingressing molecules from the surrounding environment, thereby reducing the effect of such molecules on the fiber's light-transmission properties.
1. An optical fiber with improved resistance to ingressing molecules, the fiber comprising:
a. a core for guiding at least a significant portion of incoming light; and
b. a cladding surrounding the core, the cladding containing one or more voids spaced apart from the core so as not to interfere with light travelling therein, the voids acting as trapping sites for ingressing molecules.
2. The optical fiber of claim 1 , wherein the voids extend longitudinally through the fiber.
3. The optical fiber of claim 1 , wherein the ingressing molecule is hydrogen.
4. The optical fiber of claim 1 , further comprising a hermetic coating on an outer surface of the optical fiber.
5. The optical fiber of claim 4 , wherein the coating comprises at least one of a ceramic material, a metal and a carbon-based composition.
6. The optical fiber of claim 1 , wherein the closest distance between the voids and the center of the core divided by the radius of the core is greater than 1.
7. The optical fiber of claim 1 , wherein at the closest distance between the voids and the center of the fiber, the power of transmitted light is no greater than its maximum value multiplied by 1/e 2 .
8. The optical fiber of claim 1 , where the voids form a pattern of concentric rings to create a multidirectional barrier to the diffusion of ingressing molecules toward the core.
9. The optical fiber of claim 1 , wherein at least some of the voids are filled with at least one gas capable of reacting with the ingressing molecules.
10. The optical fiber of claim 9 , wherein the gas comprises a halogen gas.
11. The optical fiber of claim 9 , wherein the gas comprises oxygen.
12. The optical fiber of claim 9 , wherein the gas comprises nitrogen.