U.S. patent application number 11/093948 was filed with the patent office on 2006-10-12 for fiber optic pigtail design for reducing insertion loss and insertion loss ripple.
This patent application is currently assigned to Avanex Corporation. Invention is credited to Giovanni Barbarossa, Di Yang.
Application Number | 20060228075 11/093948 |
Document ID | / |
Family ID | 37072492 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060228075 |
Kind Code |
A1 |
Yang; Di ; et al. |
October 12, 2006 |
FIBER OPTIC PIGTAIL DESIGN FOR REDUCING INSERTION LOSS AND
INSERTION LOSS RIPPLE
Abstract
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.
Inventors: |
Yang; Di; (Fremont, CA)
; Barbarossa; Giovanni; (Saratoga, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP
3040 POST OAK BLVD
SUITE 1500
HOUSTON
TX
77095
US
|
Assignee: |
Avanex Corporation
|
Family ID: |
37072492 |
Appl. No.: |
11/093948 |
Filed: |
March 29, 2005 |
Current U.S.
Class: |
385/43 ;
385/123 |
Current CPC
Class: |
G02B 6/3855 20130101;
G02B 6/4202 20130101; G02B 6/4249 20130101 |
Class at
Publication: |
385/043 ;
385/123 |
International
Class: |
G02B 6/26 20060101
G02B006/26 |
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.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] 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.
[0003] 2. Description of the Related Art
[0004] 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.
[0005] 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 INVENTION
[0006] An 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.
[0007] 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
[0008] FIG. 1 illustrates a system for reducing insertion loss and
insertion loss ripple, according to one embodiment of the present
invention;
[0009] FIG. 2 illustrates an end view of the first optical fiber
and the second optical fiber of FIG.1, according to one embodiment
of the present invention;
[0010] FIG. 3 illustrates the second optical fiber of FIG.1,
according to a second embodiment of the present invention;
[0011] FIG. 4 illustrates an end view of the first optical fiber
and the second optical fiber of FIG. 1, according to the second
embodiment of the present invention; and
[0012] FIG. 5 illustrates an end view of a system for reducing
insertion loss and insertion loss ripple, according to another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 illustrates a system 100 for reducing insertion
losses, according to one embodiment of the present invention. As
shown, system 100 includes, without limitation, a first optical
fiber 110 and a second optical fiber 120 inserted into a ferrule
160 in order to couple first optical fiber 110 and second optical
fiber 120 to an optical component (not shown). Epoxy 190 is used to
secure first optical fiber 110 and second optical fiber 120 within
ferrule 160 once first optical fiber 110 and second optical fiber
120 are properly positioned within ferrule 160 relative to the
optical component. In a preferred embodiment, first optical fiber
110 and second optical fiber 120 have substantially similar
configurations; therefore, for simplicity, only the configuration
of second optical fiber 120 will be described.
[0014] 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.
[0015] FIG. 2 illustrates an end view of first optical fiber 110
and second optical fiber 120 of FIG. 1, according to one embodiment
of the present invention. As shown, a second end 170 of first
optical fiber 110 abuts second end 180 of second optical fiber 120
such that the distance between an optical axis (or optical center)
210 of first optical fiber 110 and an optical axis (or optical
center) 220 of second optical fiber 120 is approximately 50
microns. Although the preferred distance between optical axis 210
and optical axis 220 is approximately 50 microns, as is described
in further detail herein, insertion loss and insertion loss ripple
are reduced so long as the distance between optical axis 210 and
optical axis 220 is between approximately 50 and approximately 125
microns.
[0016] One advantage of the system disclosed in FIGS. 1 and 2 is
that the insertion loss and insertion loss ripple related to
coupling first optical fiber 110 and second optical fiber 120 to an
optical component with ferrule 160 are reduced. Research has shown
that insertion loss and insertion loss ripple are functions of the
distance between the optical axes of the optical fibers and the
distance between the lens and mirrors of the optical component
being coupled to the optical fibers with the ferrule. Decreasing
the distance between the optical axes reduces the angular
misalignment between the optical signal output by the optical
component and the optical axis of the output optical fiber, thereby
reducing insertion loss and insertion loss ripple. Decreasing the
distance between the optical axes also reduces the sensitivity, in
terms of insertion loss and insertion loss ripple, to the distance
between the lens and mirrors of the optical component. As
previously described, the distance between optical axis 210 and
optical axis 220 in the system of FIGS. 1 and 2 is between
approximately 50 microns and approximately 125 microns (where the
preferred distance is 50 microns). By contrast, in prior art
systems where the optical fibers are not tapered, the minimum
distance between the optical axes of those optical fibers that can
be achieved is 125 microns. Thus, the present invention enables up
to a 60% decrease in the distance between optical axis 210 and
optical axis 220 relative to prior art systems.
[0017] 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%.
[0018] 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.
[0019] FIG. 3 illustrates second optical fiber 120 of FIG. 1,
according to a second embodiment of the present invention. As
before, second section 140 has a diameter of approximately 125
microns substantially throughout, and first end 152 of tapered
section 150 also has a circular cross-section with a diameter of
approximately 125 microns. In this embodiment, however, one side
305 of 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. Further, a second side 310 of the cladding
layer of tapered section 150 is untapered such that, as more
clearly shown in FIG. 4, the untapered part of second optical fiber
120 retains a semicircular shape having a diameter of approximately
125 microns. The configuration of the taper results in second end
180 of tapered section 150 having a D-shaped cross-section (as more
clearly shown in FIG. 4) and a height of approximately 88 microns.
In one embodiment, side 305 is tapered using a polishing process.
However, in other embodiments, side 305 may be tapered in any other
technically feasible fashion.
[0020] FIG. 4 illustrates an end view of first optical fiber 110
and second optical fiber 120 of FIG. 1, according to the second
embodiment of the present invention. As shown, tapered side 305 of
second end 180 of second optical fiber 120 abuts the corresponding
side of first end 170 of first optical fiber 110 such that the
distance between optical axis 210 of first optical fiber 110 and
optical axis 220 of second optical fiber 120 is approximately 50
microns. Again, as previously described herein, in alternative
embodiments, the distance between optical axis 210 and optical axis
220 may be between approximately 50 microns and 125 microns. In
addition, for purposes of this embodiment, the height (h) of second
end 180 of second optical fiber 120 (and second end 170 of first
optical fiber 110) is defined as the distance from a center 405 of
an edge formed by tapered side 305 of tapered section 150 and the
face of second end 180 to a point 410 on the edge formed by
untapered side 310 of tapered section 150 and the face of second
end 180 farthest from center 405. Again, in a preferred embodiment,
this height is approximately 88 microns.
[0021] FIG. 5 illustrates an end view of a system 500 for reducing
insertion loss and insertion loss ripple, according to another
embodiment of the present invention. As shown, system 500 includes
first optical fiber 510, a second optical fiber 520, a third
optical fiber 530 and a fourth optical fiber 540 inserted into a
ferrule (not shown). Distances 502, 504, 506 and 508 are
substantially equal and represent the distances between the optical
axes of adjacently positioned optical fibers in system 500--i.e.,
first optical fiber 510, second optical fiber 520, third optical
fiber 530 and fourth optical fiber 540, as the case may be. The
teachings of the present invention may be used to configure each of
first optical fiber 510, second optical fiber 520, third optical
fiber 530 and fourth optical fiber 540 such that each of distances
502, 504, 506 and 508 is less than approximately 88 microns. In
such a configuration, a distance 512 between the optical axes of
diagonally positioned second optical fiber 520 and third optical
fiber 530 and a distance 514 between the optical axes of diagonally
positioned first optical fiber 510 and fourth optical fiber 540 are
less than approximately 125 microns. Thus, the distances between
all optical axes are less than 125 microns, thereby resulting in
reduced insertion loss and insertion loss ripple, as previously
described herein.
[0022] 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.
[0023] 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.
* * * * *