Optical fiber element having a permanent protective coating with a shore D hardness value of 65 or more

Abstract

An optical fiber element includes an optical fiber having a numerical aperture ranging from 0.08 to 0.34 and a protective coating affixed to the outer surface of the optical fiber. The protective coating has a Shore D . .hardnees.!. .Iadd.hardness .Iaddend.value of 65 or more and remains on the optical fiber during connectorization so that the fiber is neither damaged by the blades of a stripping tool nor subjected to chemical or physical attack.

What is claimed is: 
     
       1. An optical fiber element, comprising: an optical fiber having a numerical aperture ranging from 0.08 to 0.34; . .and.!.   a protective coating affixed to the outer surface of said optical fiber, said protective coating having a Shore D hardness value of 65 or more.Iadd., wherein the protective coating remains on the outer surface of the optical fiber during connectorization and permanently thereafter.Iaddend..   
     
     
       2. The optical fiber element of claim 1 further including a buffer which substantially encloses said optical fiber and said protective coating, said buffer comprising an inner, resilient layer and an outer, rigid layer. 
     
     
       3. The optical fiber element of claim 2 wherein said inner, resilient layer has a modulus ranging from 0.5 to 20 MPa, and said outer, rigid layer has a modulus ranging from 500 to 2500 MPa. 
     
     
       4. The optical fiber element of claim 2 wherein said inner, resilient layer has a thickness ranging from 15 to 38 micrometers, and said outer, rigid layer has a thickness ranging from 25 to 48 micrometers. 
     
     
       5. The optical fiber element of claim 2 wherein said protective coating adhesively bonds with said optical fiber and with said inner, resilient layer, said bond with said optical fiber being stronger than said bond with said inner, resilient layer.Iadd., whereby the buffer may be stripped from the protective coating during connectorization such that the protective coating remains on the outer surface of the optical fiber during connectorization and permanently thereafter.Iaddend.. 
     
     
       6. The optical fiber element of claim 1 wherein said protective coating comprises an epoxy-functional polysiloxane having the structure: ##STR6## wherein: the ratio of a to b ranges from about 1:2 to about 2:1; and R is an alkyl group of one to three carbon atoms.   
     
     
       7. The optical fiber element of claim 6 wherein said protective coating further comprises a bisphenol A diglycidyl ether resin having the structure: ##STR7## wherein n ranges from 0 to 2. 
     
     
       8. The optical fiber element of claim 7 wherein said bisphenol A diglycidyl ether resin is present in said protective coating at a weight percentage ranging from about 0 to about 20, said weight percentage based on the total amount of epoxy-functional polysiloxane and bisphenol A diglycidyl ether resin present in said protective coating. 
     
     
       9. The optical fiber element of claim 7 wherein the ratio of a to b ranges from about 1:2 to about 1.5:1, and wherein said bisphenol A diglycidyl ether resin is present in said protective coating at a weight percentage ranging from about 0 to about 30, said weight percentage based on the total amount of epoxy-functional polysiloxane and bisphenol A diglycidyl ether resin present in said protective coating. 
     
     
       10. The optical fiber element of claim 6 wherein said protective coating further comprises a cycloaliphatic epoxide having the structure: ##STR8## 
     
     
       11. The optical fiber element of claim 10 wherein the ratio of a to b ranges from about 1:2 to about 1.5:1, and wherein said cycloaliphatic epoxide is present in said protective coating at a weight percentage ranging from about 0 to about 50, said weight percentage based on the total amount of epoxy-functional polysiloxane and cycloaliphatic epoxide present in said protective coating. 
     
     
       12. The optical fiber element of claim 10 wherein said protective coating further includes an alpha-olefin epoxide having the structure: ##STR9## wherein R is an alkyl of 10 to 16 carbon atoms. 
     
     
       13. The optical fiber element of claim 12 wherein: the ratio of a to b ranges from about 1.5:1 to about 2:1;   said epoxy-functional polysiloxane is present in said protective coating at a weight percentage ranging from about 27 to about 53;   said cycloaliphatic epoxide is present in said protective coating at a weight percentage ranging from about 27 to about 53; and   said alpha-olefin epoxide is present in said protective coating at a weight percentage of about 20, said weight percentages based on the total amount of epoxy-functional polysiloxane, cycloaliphatic epoxide, and alpha-olefin epoxide present in said protective coating.   
     
     
       14. The optical fiber element of claim 1 wherein said protective coating comprises a novolac epoxy having the structure: ##STR10## wherein the average value of n ranges from 0.2 to 1.8. 
     
     
       15. The optical fiber element of claim 1 wherein said protective coating comprises a bisphenol A diglycidyl ether resin having the structure: ##STR11## wherein n ranges from 0 to 2. 
     
     
       16. The optical fiber element of claim 1 wherein said protective coating has a thickness ranging from 8 to 23 micrometers. 
     
     
       17. The optical fiber element of claim 2 wherein said optical fiber and said protective coating have a combined diameter ranging from about 120 to about 130 micrometers. 
     
     
       18. The optical fiber element of claim 17 wherein the total diameter of said optical fiber element ranges from about 240 to about 260 micrometers. 
     
     
       19. The optical fiber element of claim 1 wherein said optical fiber is capable of supporting multiple modes and has a numerical aperture ranging from about 0.26 to about 0.29. 
     
     
       20. The optical fiber element of claim 1 wherein said optical fiber is capable of supporting one mode and has a numerical aperture ranging from about 0.11 to about 0.20. 
     
     
       21. A method for producing an optical fiber element comprising the steps of: providing an optical fiber having a numerical aperture ranging from 0.08 to 0.34; and   affixing a protective coating to the outer surface of said optical fiber, said protective coating having a Shore D hardness value of 65 or more.   
     
     
       22. The method of claim 21 further including the step of applying a buffer which substantially encloses said optical fiber and said protective coating, said buffer comprising an inner, resilient layer and an outer, rigid layer. 
     
     
       23. The method of claim 22 wherein said inner, resilient layer has a modulus ranging from 0.5 to 20 MPa, and said outer, rigid layer has a modulus ranging from 500 to 2500 MPa. 
     
     
       24. The method of claim 23 wherein said inner, resilient layer is applied at a thickness ranging from 15 to 38 micrometers, and said outer, rigid layer is applied at a thickness ranging from 25 to 48 micrometers. 
     
     
       25. The method of claim 22 wherein said protective coating adhesively bonds with said optical fiber and with said inner, resilient layer, said bond with said optical fiber being stronger than said bond with said inner, resilient layer. 
     
     
       26. The method of claim 22 wherein said optical fiber and said protective coating have a combined diameter ranging from about 120 to about 130 micrometers. 
     
     
       27. The method of claim 26 wherein the total diameter of said optical fiber element ranges from about 240 to about 260 micrometers. 
     
     
       28. The method of claim 21 wherein said protective coating is applied at a thickness ranging from 8 to 23 micrometers. 
     
     
       29. The method of claim 21 wherein said protective coating comprises an epoxy-functional polysiloxane having the structure: ##STR12## wherein: the ratio of a to b ranges from about 1:2 to about 2:1; and R is an alkyl group of one to three carbon atoms.   
     
     
       30. The method of claim 29 wherein said protective coating further comprises a bisphenol A diglycidyl ether resin having the structure: ##STR13## wherein n ranges from 0 to 2. 
     
     
       31. The method of claim 30 wherein said bisphenol A diglycidyl ether resin is present in said protective coating at a weight percentage ranging from about 0 to about 20, said weight percentage based on the total amount of epoxy-functional polysiloxane and bisphenol A diglycidyl ether resin present in said protective coating. 
     
     
       32. The method of claim 30 wherein the ratio of a to b ranges from about 1:2 to about 1.5:1, and wherein said bisphenol A diglycidyl ether resin is present in said protective coating at a weight percentage ranging from about 0 to about 30, said weight percentage based on the total amount of epoxy-functional polysiloxane and bisphenol A diglycidyl ether resin present in said protective coating. 
     
     
       33. The method of claim 29 wherein said protective coating further comprises a cycloaliphatic epoxide having the structure: ##STR14## 
     
     
       34. The method of claim 33 wherein the ratio of a to b ranges from about 1:2 to about 1.5:1, and wherein said cycloaliphatic epoxide is present in said protective coating at a weight percentage ranging from about 0 to about 50, said weight percentage based on the total amount of epoxy-functional polysiloxane and cycloaliphatic epoxide present in said protective coating. 
     
     
       35. The method of claim 33 wherein said protective coating further includes an alpha-olefin epoxide having the structure ##STR15## wherein R is an alkyl of 10 to 16 carbon atoms. 
     
     
       36. The method of claim 35 wherein: the ratio of a to b ranges from about 1.5:1 to about 2:1;   said epoxy-functional polysiloxane is present in said protective coating at a weight percentage ranging from about 27 to about 53;   said cycloaliphatic epoxide is present in said protective coating at a weight percentage ranging from about 27 to about 53; and   said alpha-olefin epoxide is present in said protective coating at a weight percentage of about 20, said weight percentages based on the total amount of epoxy-functional polysiloxane, cycloaliphatic epoxide, and alpha-olefin epoxide in said protective coating.   
     
     
       37. The method of claim 21 wherein said protective coating comprises a novolac epoxy having the structure: ##STR16## wherein n ranges from 0.2 to 1.8. 
     
     
       38. The method of claim 21 wherein said protective coating comprises a bisphenol A diglycidyl ether resin having the structure: ##STR17## wherein n ranges from 0 to 2. .Iadd. 
     
     
       39.  A method for connecting an optical fiber element to a device, wherein the optical fiber element comprises: an optical fiber with a numerical aperture ranging from 0.08 to 0.34;   a protective coating affixed to the outer surface of said optical fiber, said protective coating having a Shore D hardness value of 65 or more; and   a buffer which substantially encloses said optical fiber and said protective coating; the method comprising:     removing the buffer from the protective coating such that the protective coating remains affixed to the outer surface of the optical fiber; and   inserting the optical fiber with affixed protective coating into the device to provide optical interconnection..Iaddend.