FIBER OPTIC PIGTAIL DESIGN FOR REDUCING INSERTION LOSS AND INSERTION LOSS RIPPLE
One embodiment of an optical fiber for reducing insertion loss and insertion loss ripple includes a tapered region where the optical fiber has a diameter of approximately 125 microns at a first end and a diameter of approximately 50 microns at a second end. The cladding layer of the tapered region is tapered from the first end towards the second end. This section of the optical fiber may be tapered using an etch process or any other technically feasible process. The tapered configuration enables the distance between the optical axes of two optical fibers inserted into a ferrule to be reduced from approximately 125 microns to approximately 50 microns. Decreasing the distance between the optical axes causes a reduction in both insertion loss and insertion loss ripple.
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1. Field of the Invention
The present invention relates generally to optical devices and, more particularly, to a fiber optic pigtail design for reducing insertion loss and insertion loss ripple.
2. Description of the Related Art
Bulk fiber (i.e., fiber with a 125 micron cladding diameter) is the most widely used fiber in fiber optic data and communications systems. Although fairly well-established as an industry standard, one well-known drawback of bulk fiber is that traditional methods of coupling these fibers to optical components with ferrules result in relatively high insertion loss and insertion loss ripple. High losses are particularly problematic when optical devices, such as dispersion compensators, are designed using several cascaded optical components, each of which is coupled to one or more optical fibers with a ferrule. For example, some dispersion compensator designs may include upwards of ten or more cascaded optical components. If the insertion loss and insertion loss ripple associated with each individual optical component are too great, then the compounded losses across the dispersion compensator may ultimately render the device unusable.
As the foregoing illustrates, there is a need in the art for a fiber optic pigtail design that reduces insertion loss and insertion loss ripple when bulk fiber is coupled to an optical component with a ferrule.
SUMMARY OF THE INVENTIONAn optical fiber configured for reduced insertion loss and insertion loss ripple includes a first section having a first diameter and a second section having a second diameter, where the first diameter is greater than the second diameter. The optical fiber also includes a third section having a first end with a first cross-sectional area and a second end with a second cross-sectional area, where the first cross-sectional area is greater than the second cross-sectional area. Further, the third section is tapered from the first end towards the second end.
One advantage of the disclosed optical fiber is that the tapered configuration enables the distance between the optical axes of two optical fibers inserted into a ferrule to be reduced from approximately 125 microns to approximately 50 microns. Decreasing the distance between the optical axes causes a reduction in both insertion loss and insertion loss ripple.
BRIEF DESCRIPTION OF THE DRAWINGS
Second optical fiber 120 has a first section 130, a second section 140 and a tapered section 150. First section 130 has a diameter of approximately 250 microns substantially throughout and extends approximately 0.5 to 0.8 millimeters into ferrule 160. First section 130 includes a core, a cladding layer and a coating. Second section 140 has a diameter of approximately 125 microns substantially throughout and extends approximately 0.3 to 0.6 millimeters further into ferrule 160 from the end of first section 130. The coating of second optical fiber 120 is stripped away from second section 140, leaving only the core and the cladding layer. Tapered section 150 has a first end 152 and a second end 180. Both first end 152 and second end 180 have circular cross-sections. The diameter of tapered section 150 at first end 152 is approximately 125 microns (i.e., substantially the same as the diameter of second section 140), and the diameter of tapered section 150 at second end 180 is approximately 50 microns. The cladding layer of tapered section 150 is tapered from first end 152 towards second end 180 over a length of approximately 0.9 to 1.2 millimeters. In one embodiment, tapered section 150 is tapered using an etch process. However, in other embodiments, tapered section 150 may be tapered in any other technically feasible fashion.
One advantage of the system disclosed in
Experiments have shown that decreasing the distance between optical axes causes a corresponding reduction in insertion loss and insertion loss ripple. For example, in a system comprising two untapered 125 micron optical fibers, a 6 millimeter collimator lens and an optical component coupled to the two optical fibers with a ferrule, where a distance of 5 millimeters separates the collimator lens and the mirrors of the optical component, the insertion loss is 0.31 dB and the insertion loss ripple is 0.32 dB. By contrast, the insertion loss is 0.23 dB and the insertion loss ripple is 0.12 dB for the same system when the two untapered optical fibers are replaced with two optical fibers configured in accordance with the teachings of the present invention. As the foregoing illustrates, the present invention reduces the insertion loss by approximately 26% and the insertion loss ripple by approximately 62%.
As previously described, in a preferred embodiment, the configurations of first optical fiber 110 and second optical fiber 120 are substantially the same. However, in alternative embodiments, first optical fiber 110 and second optical fiber 120 may have different configurations, so long as the distance between optical axis 210 and optical axis 220 is between approximately 50 microns and approximately 125 microns.
In a preferred embodiment, each of distances 502, 504, 506 and 508 is approximately 50 microns and each of distances 512 and 514 is approximately 71 microns. In alternative embodiments, first optical fiber 510, second optical fiber 520, third optical fiber 530 and fourth optical fiber 540 may have substantially equivalent or different configurations, and distances 502, 504, 506 and 508 may be different from one another, so long as each of distances 502, 504, 506, 508, 512 and 514 is less than approximately 125 microns.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims
1-11. (canceled)
12. The system of claim 21, wherein a distance from the first optical axis at the second end of the third section of the input optical fiber and the second optical axis at the second end of the third section of the output optical fiber is between approximately 50 microns and approximately 125 microns.
13. The system of claim 12, wherein the distance between the first optical axis and the second optical axis is approximately 50 microns.
14. The system of claim 21, wherein the first end of the third section of the output optical fiber has a diameter of approximately 125 microns, and the second end of the third section of the output optical fiber has a circular cross-section with a diameter of approximately 50 microns.
15. The system of claim 14, wherein the third section of the output optical fiber is tapered using an etch process.
16. The system of claim 14, wherein the first diameter of the output optical fiber is approximately 250 microns, and the second diameter of the output optical fiber is approximately 125 microns.
17. The system of claim 21, wherein the second end of the third section of the output optical fiber has a D-shaped cross-section.
18. The optical fiber of claim 17, wherein the third section of the output optical fiber is tapered on one side using a polishing process.
19. The system of claim 17, wherein the first end of the third section of the output optical fiber has a diameter of approximately 125 microns, and the second end of the third section of the output optical fiber has a height of approximately 87-89 microns.
20. The system of claim 18, wherein the first diameter of the output optical fiber is approximately 250 microns, and the second diameter of the output optical fiber is approximately 125 microns.
21. A system for reducing insertion loss and insertion ripple when coupling optical fiber to an optical component, the system comprising:
- a ferrule coupled to the optical component;
- an input optical fiber having a first optical axis and a first end inserted into the ferrule and configured for transmitting an optical signal to the optical component, the input optical fiber further having: a first section having a first diameter, a second section having a second diameter, wherein the first diameter is greater than the second diameter, and a third section having a first end with the first cross-sectional area and a second end with a second cross-sectional area, wherein the first cross-sectional area is greater than the second cross-sectional area, and the third section is tapered from the first end towards the second end; and
- an output optical fiber having a second optical axis and a first end inserted into the ferrule and configured for receiving the optical signal reflected from the optical component, the output optical fiber further having: a first section having a first diameter, a second section having a second diameter, wherein the first diameter is greater than the second diameter, and a third section having a first end with the first cross-sectional area and a second end with a second cross-sectional area, wherein the first cross-sectional area is greater than the second cross-sectional area, and the third section is tapered from the first end towards the second end.
22. The system of claim 21, wherein the first end of the third section of the input optical fiber has a diameter of approximately 125 microns, and the second end of the third section of the input optical fiber has a circular cross-section with a diameter of approximately 50 microns.
23. The system of claim 22, wherein the third section of the input optical fiber is tapered using an etch process.
24. The system of claim 22, wherein the first diameter of the input optical fiber is approximately 250 microns, and the second diameter of the input optical fiber is approximately 125 microns.
25. The system of claim 21, wherein the second end of the third section of the input optical fiber has a D-shaped cross-section.
26. The optical fiber of claim 25, wherein the third section of the input optical fiber is tapered on one side using a polishing process.
27. The system of claim 25, wherein the first end of the third section of the input optical fiber has a diameter of approximately 125 microns, and the second end of the third section of the input optical fiber has a height of approximately 87-89 microns.
28. The system of claim 26, wherein the first diameter of the input optical fiber is approximately 250 microns, and the second diameter of the input optical fiber is approximately 125 microns.
Type: Application
Filed: Mar 29, 2005
Publication Date: Oct 12, 2006
Applicant:
Inventors: Di Yang (Fremont, CA), Giovanni Barbarossa (Saratoga, CA)
Application Number: 11/093,948
International Classification: G02B 6/26 (20060101);