Optical fiber with gratings and methods of forming thereof
Embodiments of the current disclosure include small diameter single-mode optical fibers having gratings and methods of forming thereof. In some embodiments, methods of forming a small diameter single-mode optical fibers having gratings include providing an optical fiber having a core and cladding with a combined outer diameter of 100 μm to 125 μm and a coating having a thickness of less than or equal to 20 μm, wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer; and exposing the core, through the coating, to a pattern of ultraviolet radiation to form an optical grating within the core.
1. A method, comprising:
providing an optical fiber comprising a core region, a cladding region surrounding the core region and a coating surrounding the cladding region;
wherein the core and cladding have a combined outer diameter of 100 μm to 125 μm,
wherein the coating has a thickness of less than or equal to 20 μm, and wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region, wherein the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer, wherein the low-modulus coating layer has a Young's modulus of less than or equal to 5 MPa and the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa; and
exposing the core, through the coating, to a pattern of ultraviolet radiation to form an optical grating within the core.
2. The method of claim 1 , wherein a ratio of a thickness of the low-modulus coating layer to a thickness of the high-modulus coating layer is from 0.8 to 1.2.
3. The method of claim 1 , wherein the coated optical fiber has a diameter of less than or equal to 145 μm.
4. The method of claim 1 , wherein the cladding of the optical fiber comprises a Titania-doped layer.
5. The method of claim 1 , wherein the coating has a thickness of less than or equal to 15 μm.
6. The method of claim 1 , wherein the coating has a thickness of less than or equal to 10 μm.
7. The method of claim 1 , wherein the coating has a thickness of less than or equal to 2 μm.
8. The method of claim 1 , wherein the coating is a UV curable material.
9. The method of claim 1 , wherein the optical grating has a period of about 200 nm to about 1500 microns.
10. The method of claim 1 , wherein the optical grating reflectivity is about 1×10 −6 to about 2×10 −4 per meter.
11. The method of claim 1 , further comprising transferring the optical fiber from a first reel to a second reel while exposing the core, through the coating, to a pattern of ultraviolet radiation to form an optical grating within the core.
12. An optical fiber comprising:
a core region having a plurality of optical gratings within the core
a cladding region surrounding the core region, wherein the core and cladding have a combined outer diameter of 100 μm to 125 μm; and
a coating surrounding the cladding region, wherein the coating has a thickness of less than or equal to 20 μm, and wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region, wherein the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer, wherein the low-modulus coating layer has a Young's modulus of less than or equal to 5 MPa and the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa.
13. The optical fiber of claim 12 , wherein a ratio of a thickness of the low-modulus coating layer to a thickness of the high-modulus coating layer is from 0.8 to 1.2.
14. The optical fiber of claim 12 , wherein the coated optical fiber has a diameter of less than or equal to 145 μm.
15. The optical fiber of claim 12 , wherein the cladding of the optical fiber comprises a Titania-doped layer.
16. The optical fiber of claim 12 , wherein the coating has a thickness of less than or equal to 15 μm.
17. The optical fiber of claim 12 , wherein the coating is a UV curable material.
18. The optical fiber of claim 12 , wherein the optical grating has a period of about 200 nm to about 1500 microns.
19. The optical fiber of claim 12 , wherein the optical grating reflectivity is about 1×10 −6 to about 2×10 −4 per meter.
20. An optical sensing system, comprising:
a control system comprising a light source, a light detector, and a processor;
an optical fiber; and
a light transmitting member operably coupling the optical fiber to the control system, wherein the optical fiber comprises:
a core region having a plurality of optical gratings within the core;
a cladding region surrounding the core region, wherein the core and cladding have a combined outer diameter of 100 μm to 125 μm; and
a coating surrounding the cladding region, wherein the coating has a thickness of less than or equal to 20 μm, and wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region, wherein the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer, wherein the low-modulus coating layer has a Young's modulus of less than or equal to 5 MPa and the high-modulus coating layer has a Young's modulus of greater than or equal to 0.5 GPa.