U.S. patent application number 09/255333 was filed with the patent office on 2001-10-04 for tuned multiple fiber optic connector.
Invention is credited to CHONG, NYUEN.
Application Number | 20010026662 09/255333 |
Document ID | / |
Family ID | 22129054 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010026662 |
Kind Code |
A1 |
CHONG, NYUEN |
October 4, 2001 |
TUNED MULTIPLE FIBER OPTIC CONNECTOR
Abstract
A tuned multiple fiber optical connector and a method for tuning
same is disclosed. A first connector housing retains each of a
first plurality of optical fiber ends in a predetermined location.
The first connector housing has a first key element. A core of each
of the first plurality of optical fiber ends is oriented in a
predetermined fashion with respect to the first key element. A
second connector housing retains each of a second plurality of
optical fiber ends in a predetermined location. The second
connector housing comprises a second key element. A core of each of
the second plurality of optical fiber ends is oriented in a
predetermined fashion with respect to the second key element. The
first and the second connector housings are coupled such that the
key elements are disposed in a predetermined relation one to the
other. Therefore, the core of each of the first plurality of
optical fiber ends is substantially in alignment with the core of a
corresponding optical fiber end of the second plurality of optical
fiber ends.
Inventors: |
CHONG, NYUEN; (KANATA,
CA) |
Correspondence
Address: |
NEIL TEITELBAUM
NEIL TEITELBAUM & ASSOCIATES
834 COLONEL BY DRIVE
OTTAWA
K1S5C4
CA
|
Family ID: |
22129054 |
Appl. No.: |
09/255333 |
Filed: |
February 23, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60075965 |
Feb 24, 1998 |
|
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|
Current U.S.
Class: |
385/59 |
Current CPC
Class: |
G02B 6/3843 20130101;
G02B 6/3885 20130101; G02B 6/3831 20130101; G02B 6/3851 20130101;
G02B 6/383 20130101; G02B 6/3834 20130101; G02B 6/3873 20130101;
G02B 6/3825 20130101 |
Class at
Publication: |
385/59 |
International
Class: |
G02B 006/38 |
Claims
What is claimed is:
1. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends comprising: a first connector housing comprising at
least a first key element, the connector housing for retaining each
of the first plurality of optical fibre ends, a core of each of the
first plurality of optical fibre ends oriented with respect to the
same first key element in a predetermined fashion in a plane
perpendicular to the longitudinal axis of the fibre; and, a
coupling mechanism for coupling the first connector housing to
another connector housing.
2. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, comprising: a second connector
housing comprising a second key element, the second connector
housing for retaining each of the second plurality of optical fibre
ends in a predetermined location and a core of each of the second
plurality of optical fibre ends oriented in a plane perpendicular
to the longitudinal axis of the fibre in a predetermined fashion
with respect to the second key element; and, a coupling mechanism
for coupling the second connector housing to the first connector
housing such that when the second key element and the first key
element are disposed in a predetermined relation one to the other,
the core of each of the second plurality of optical fibre ends is
approximately in alignment with the core of a corresponding optical
fibre end of the first plurality of optical fibre ends.
3. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the first key element is
a mating key element for substantially limiting coupling of the
first connector housing and another second connector housing to a
single orientation.
4. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the first connector
housing comprises a plurality of bores, each bore for retaining one
optical fibre end.
5. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the first connector
housing comprises a bore for retaining a plurality of optical fibre
ends.
6. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the coupling mechanism
comprises one of a male first connector housing and a female first
connector housing.
7. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 2, wherein the coupling mechanism
comprises a third connector housing for coupling the first
connector housing to the second connector housing.
8. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the first connector
housing and another second connector housing are substantially
identical and mate one with the other in one and only one
orientation.
9. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the key element comprises
a pin.
10. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the key element comprises
a coloured mark.
11. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 2, wherein the first and second key
elements comprise the first connector housing and the other second
connector housing, the first connector housing having a mating
asymmetric shape.
12. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein all cores of the optical
fibre ends are oriented toward a same side of the centers of the
corresponding bores in a plane perpendicular to the longitudinal
axis of the fibre.
13. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the cores of the optical
fibre ends on one side of a line of symmetry of the connector are
oriented in a plane perpendicular to the longitudinal axis of the
fibre, the orientation in a first direction and the cores of the
optical fibre ends on the other side of the line of symmetry are
oriented in a plane perpendicular to the longitudinal axis of the
fibre, the orientation in a second opposite direction.
14. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 1, wherein the bores are arranged in
a circular fashion and the cores of the optical fibre ends are
oriented in a same direction in a plane perpendicular to the
longitudinal axes of the fibers relative to a straight line through
a center of the circle and a center of each bore.
15. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends comprising: a first plurality of optical fibre ends,
wherein each optical fibre end is retained in a ferrule having at
least an indicator element such that a core of the optical fibre
end is oriented in a plane perpendicular to the longitudinal axis
of the fibre, the orientation in a predetermined fashion with
respect to an indicator element of the ferrule; a first connector
housing comprising a first key element, the first connector housing
for retaining each of the first plurality of optical fibre ends in
a predetermined location such that the indicator elements of the
ferrules are disposed in a predetermined relation to the first key
element of the first connector housing; and, a coupling mechanism
for coupling the first connector housing to another connector
housing.
16. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 15, comprising: a second plurality
of optical fibre ends, wherein each optical fibre end is retained
in a ferrule such that a core of the optical fibre end is oriented
in a plane perpendicular to the longitudinal axis of the fibre, the
orientation in a predetermined fashion with respect to an indicator
element of the ferrule; a second connector housing comprising a
second key element, the second connector housing for retaining each
of the second plurality of optical fibre ends in a predetermined
location such that the indicator elements of the ferrules are
disposed in a predetermined relation to the second key element of
the connector housing; and, a coupling mechanism for coupling the
second connector housing to the first connector housing such that
when the second key element and a first key element of the first
connector housing are disposed in a predetermined relation one to
the other, the core of each of the second plurality of optical
fibre ends is substantially in alignment with the core of a
corresponding optical fibre end of the first plurality of optical
fibre ends retained in the first connector housing.
17. A tuned multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 15, wherein the ferrule retains a
plurality of optical fibre ends.
18. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends retained within a plurality of
ferrules to a second plurality of optical fibre ends comprising: a
first connector housing comprising a first key element, the first
connector housing for retaining each of the plurality of ferrules
in an opening within the first connector housing in one of a
plurality of orientations in a plane perpendicular to the
longitudinal axis of the opening and prevented from rotating by
engaging means; and, a coupling mechanism for coupling the first
connector housing and another connector housing.
19. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 18 comprising: a plurality of
ferrules, each ferrule for retaining an optical fibre end having a
core wherein the ferrules are physically keyed for insertion into
the openings within the first connector housing in each of at least
two different orientations.
20. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 19 comprising: a first plurality of
optical fibre ends, wherein each optical fibre end is retained in a
ferrule from the plurality of ferrules.
21. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 20, comprising: a second plurality
of optical fibre ends, wherein each optical fibre end is retained
in a ferrule; a second connector housing comprising a second key
element, the second connector housing for retaining each of the
second plurality of optical fibre ends in a predetermined location
such that each ferrule is retained in an opening within the second
connector housing in one of a plurality of orientations in a plane
perpendicular to the longitudinal axis of the opening and prevented
from rotating by engaging means; and, a coupling mechanism for
coupling the second connector housing and the first connector
housing such that when the key elements are disposed in a
predetermined relation one to the other, the core of each of the
second plurality of optical fibre ends is in a predetermined
orientation in a plane perpendicular to the longitudinal axis of
the bore with respect to the core of a corresponding optical fibre
end of the first plurality of optical fibre ends.
22. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 19, wherein the engaging means
comprises a cylindrical ferrule having a flattened face for
engaging with one of four sidewalls of the opening, the opening
having a quadratic cross section.
23. A tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends as defined in claim 19, wherein the engaging means
comprises a cylindrical ferrule having etched grooves for engaging
with a pin mounted within the opening.
24. A method for tuning a multiple fibre optic connector for
connecting a plurality of optical fibre ends comprising the steps
of: iteratively, determining a core orientation in a plane
perpendicular to the longitudinal axis of the core within the
fibre, the orientation with respect to a reference point of each
optical fibre end of the plurality of optical fibre ends; when a
core orientation is a predetermined orientation in the plane,
affixing the optical fibre ends in a connector housing such that
the core of each of the optical fibre ends is oriented in the plane
in a predetermined fashion with respect to a key element of the
connector housing; and, when the core orientation is other than the
predetermined orientation, altering the core orientation of at
least one of the plurality of optical fibre ends.
25. A method for tuning a multiple fibre optic connector for
connecting a plurality of optical fibre ends comprising the steps
of: determining a core orientation in a plane perpendicular to the
longitudinal axis of the core within the fibre, the orientation
with respect to a reference point of each optical fibre end of the
plurality of optical fibre ends; when a core orientation is a
predetermined orientation, affixing the optical fibre end in a
ferrule such that the core of the optical fibre end is oriented in
a plane perpendicular to the longitudinal axis of the fibre, the
orientation in a predetermined fashion with respect to an indicator
element of the ferrule; when the core orientation is other than the
predetermined orientation, altering the core orientation; and,
affixing the ferrules in a connector housing such that the
indicator elements of the ferrules are disposed in a predetermined
relation to a key element of the connector housing.
26. A method for tuning a multiple fibre optic connector for
connecting a first plurality of optical fibre ends to a second
plurality of optical fibre ends comprising the steps of: affixing
each of the first plurality and the second plurality of optical
fibre ends in a ferrule; mating a first connector housing with a
second connector housing such that key elements are disposed in a
predetermined relation one to the other indicating mating of the
two connector housings in one and only one orientation; placing
each of the first plurality of optical fibre ends and the
corresponding fibre of the second plurality of optical fibre ends
into a first and second connector housing, respectively, such that
cores of the first plurality of optical fibre ends and the
corresponding core of the second plurality of optical fibre ends
have a first orientation relative to each other in a plane
perpendicular to the longitudinal axis of the core within the
fibre; simultaneously launching light through each of the first and
second plurality of optical fibres; adjusting the relative
orientation of the cores of each fibre pair until a preferred
coupling is obtained; and, when a preferred coupling is obtained
securing the orientation of the fibre cores with respect to the key
elements by affixing the ferrules within the connector housings.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a connector for receiving
and connecting multiple optical fiber ends. In particular, the
present invention relates to a tunable multiple optical fiber
connector for tuning the core position of each fiber in the
connector to optimize coupling efficiency.
BACKGROUND OF THE INVENTION
[0002] In fibre based optical systems, signals propagate within
optical fibres. When optically coupling two components, a fiber is
coupled at a first end to a first component and at a second end to
a second component. Often in an optical system, a plurality of
fibres is routed within the system. When a large number of fibres
are used, designs often incorporate cables comprising a number of
fibres and having a single connector at each end of the cable. The
single multi-fibre connector is provided with bores for accepting
optical fibres. Into each bore, a fiber is inserted and held in
place. Unfortunately, the bores are not always precisely located
and, in order to insert a fibre, the bores must be larger in
diameter than the outside diameter of the fibres in order to
accommodate the fibres.
[0003] Small irregularities in ferrule and fibre manufacture can
result in significant signal loss, particularly in coupling single
mode fibres. A standard ferrule has an internal diameter closely
matching a fibre diameter. However, a ferrule having for example an
internal diameter of 128 .mu.m provided with a fibre having a
diameter of 127 .mu.m may be placed up to 0.5 .mu.m from the
concentric axis, equalling a total possible eccentricity of the
optical fibre of 1 .mu.m. In addition, the bore of the ferrule in
manufacture may not be concentrically placed. Tuning is thus
necessary to optimize the position of the fibre ends within a
connector and thereby adjust the coupling efficiency. For example,
a simple tuning apparatus allows for insertion of a connector in
any of a plurality of orientations. Once inserted, the connector is
fixed in its orientation and, therefore, the coupling efficiency
remains substantially constant and is improved when coupling is
between two ends having similar orientations.
[0004] Unfortunately, when using cables comprising multiple fibres,
each fibre coupling may result in significant loss. Tuning of
fibres by moving the two connector ends does not result in each
fibre pair being independently tunable. The relative placement of
the connector ends cannot be reoriented because the fibre
connections would change. When different fibres within a cable have
alignment errors as is commonly noted, it is near impossible to
find two connectors that couple efficiently for all fibre pairs.
For example, when correct alignment is sufficiently approximated by
aligning the connectors in one of four orientations, there is a one
in four chance of a good coupling. Through tuning of a single fibre
connector, the coupling is easily altered to achieve a most
efficient coupling from the four available orientations. When two
fibres are incorporated into a cable, there are 16 possible
orientations and since tuning is not available, only one in 16
connectors provides good coupling with an existing connector. When
a cable having 32 fibres is used, the chance of finding two that
mate with reasonable coupling efficiency is very small.
[0005] For more efficient installation of multi fiber or ribbon
fibres the coupling of multiple fibre ends at a single
multi-fibre-connector pair, heretofore, has not been satisfactory.
U.S. Pat. No. 5,671,311 to Stillie et al. discloses a method of
aligning a number of receiving ferrules within a less precise
housing by providing aligning pins for locating the ferrule bores
in the housing. Once the ferrules are positioned the fibres are
then inserted. This is a rather imprecise method, which does not
provide an opportunity to correct transmission problems once the
fibres and light sources are in place. Also, since the fibre is
inserted after the tuning is performed, slack between the ferule
and the fibre can be a significant problem.
[0006] Alternative multiple fibre connectors are disclosed in U.S.
Pat. No. 5,430,819 to Sizer II et al. A first connector
manufactured by AT&T under the trademark MACII, secures a
plurality of exposed fibre ends between a pair of silicon wafers
having a groove precision etched to locate each fibre end. A second
connector in accordance with the invention of Sizer II et al.
provides a pair of substrate plates having fibre-sized holes etched
through the substrate for locating each fibre end. Both of these
methods require absolutely precise manufacturing at considerable
cost, since no tuning adjustment of individual fibres is
possible.
[0007] Tuning of single optical fibre connectors is known. For
example, it is known to provide a keying mechanism on an optical
fibre connector to prevent rotation of the optical fibre cable once
a desired coupling position has been determined, as described in
U.S. Pat. No. 5,096,276 to Gerace et al. The key element may be an
asymmetric shape or a pin or the like in a push-pull plug type
connector.
[0008] Two fibre ends joined in a connector may each be supported
in a ferrule or similar housing. Most commonly a cylindrical
ferrule with a central bore substantially the diameter of the
exposed fibre is used to support the fibre end within the
connector. As recognized in U.S. Pat. No. 4,738,508 to Palmquist,
and also in U.S. Pat. No. 5,390,269 to Palacek et al., tuning of
the ferrules within the connector is also needed to achieve high
performance connection with low insertion loss.
[0009] Palacek and Palmquist propose providing multiple rotatable
orientations of a fibre and ferrule within the connector by placing
the ferrule within a housing or collar having facets or knurls for
mating with a receiving housing.
[0010] It is an object of the invention to provide a connector for
receiving and connecting multiple optical fibre ends, in which each
optical fibre core is oriented in a predetermined fashion with
respect to a key element of a connector housing.
[0011] It is further an object of the invention to provide a
connector for receiving and connecting multiple optical fibre ends,
in which each optical fibre core can be tuned individually.
SUMMARY OF THE INVENTION
[0012] According to the present invention there is provided a tuned
multiple fibre optic connector for connecting a first plurality of
optical fibre ends to a second plurality of optical fibre ends
comprising:
[0013] a first connector housing comprising a first key element,
the first connector housing for retaining each of the first
plurality of optical fibre ends in a predetermined location, a core
of each of the first plurality of optical fibre ends oriented in a
predetermined fashion with respect to the first key element;
[0014] a second connector housing comprising a second key element,
the second connector housing for retaining each of the second
plurality of optical fibre ends in a predetermined location and a
core of each of the second plurality of optical fibre ends oriented
in a predetermined fashion with respect to the second key element;
and,
[0015] a coupling mechanism for coupling the first and the second
connector housings such that when the key elements are disposed in
a predetermined relation one to the other, the core of each of the
first plurality of optical fibre ends is substantially in aligmnent
with the core of a corresponding optical fibre end of the second
plurality of optical fibre ends.
[0016] In a preferred embodiment according to the invention there
is further provided a tuned multiple fibre optic connector for
connecting a first plurality of optical fibre ends to a second
plurality of optical fibre ends comprising:
[0017] a first plurality of optical fibre ends, wherein each
optical fibre end is retained in a ferrule such that a core of the
optical fibre end is oriented in a predetermined fashion with
respect to a key element of the ferrule;
[0018] a second plurality of optical fibre ends, wherein each
optical fibre end is retained in a ferrule such that a core of the
optical fibre end is oriented in a predetermined fashion with
respect to a key element of the ferrule;
[0019] a first connector housing comprising a first key element,
the first connector housing for retaining each of the first
plurality of optical fibre ends in a predetermined location such
that the key elements of the ferrules are disposed in a
predetermined relation to the first key element of the connector
housing;
[0020] a second connector housing comprising a second key element,
the second connector housing for retaining each of the second
plurality of optical fibre ends in a predetermined location such
that the key elements of the ferrules are disposed in a
predetermined relation to the second key element of the connector
housing; and,
[0021] a coupling mechanism for coupling the first and the second
connector housings such that when the first and the second key
elements are disposed in a predetermined relation one to the other,
the core of each of the first plurality of optical fibre ends is
substantially in alignment with the core of a corresponding optical
fibre end of the second plurality of optical fibre ends.
[0022] According to the invention there is further provided a
tunable multiple fibre optic connector for connecting a first
plurality of optical fibre ends to a second plurality of optical
fibre ends comprising:
[0023] a first plurality of optical fibre ends, wherein each
optical fibre end is retained in a ferrule;
[0024] a second plurality of optical fibre ends, wherein each
optical fibre end is retained in a ferrule;
[0025] a first connector housing comprising a first key element,
the first connector housing for retaining each of the first
plurality of optical fibre ends in a predetermined location such
that each ferrule is retained in a bore within the first connector
housing in one of a plurality of orientations and prevented from
rotating by engaging means;
[0026] a second connector housing comprising a second key element,
the second connector housing for retaining each of the second
plurality of optical fibre ends in a predetermined location such
that each ferrule is retained in a bore within the second connector
housing in one of a plurality of orientations and prevented from
rotating by engaging means; and,
[0027] a coupling mechanism for coupling the first and the second
connector housings such that when the key elements are disposed in
a predetermined relation one to the other, the core of each of the
first plurality of optical fibre ends is in a predetermined
orientation with respect to the core of a corresponding optical
fibre end of the second plurality of optical fibre ends.
[0028] According to the present invention there is provided a
method for tuning a multiple fibre optic connector for connecting a
plurality of optical fibre ends comprising the steps of:
iteratively,
[0029] determining a core orientation with respect to a reference
point of each optical fibre end of the plurality of optical fibre
ends;
[0030] when a core orientation is a predetermined orientation,
affixing the optical fibre ends in a connector housing such that
the core of each of the optical fibre ends is oriented in a
predetermined fashion with respect to a key element of the
connector housing; and,
[0031] when the core orientation is other than the predetermined
orientation, altering the core orientation of at least one of the
plurality of optical fibre ends.
[0032] In a preferred embodiment according to the present invention
there is further provided a method for tuning a multiple fibre
optic connector for connecting a plurality of optical fibre ends
comprising the steps of:
[0033] determining a core orientation with respect to a reference
point of each optical fibre end of the plurality of optical fibre
ends;
[0034] when a core orientation is a predetermined orientation,
affixing the optical fibre end in a ferrule such that the core of
the optical fibre end is oriented in a predetermined fashion with
respect to a key element of the ferrule;
[0035] when the core orientation is other than the predetermined
orientation, altering the core orientation; and,
[0036] affixing the ferrules in a connector housing such that the
key elements of the ferrules are disposed in a predetermined
relation to a key element of the connector housing.
[0037] In another preferred embodiment according to the present
invention there is provided a method for tuning a multiple fibre
optic connector for connecting a first plurality of optical fibre
ends to a second plurality of optical fibre ends comprising the
steps of:
[0038] affixing each of the first plurality and the second
plurality of optical fibre ends in a ferrule;
[0039] mating a first connector housing with a second connector
housing such that key elements are disposed in a predetermined
relation one to the other indicating mating of the two connector
housings in one and only one orientation;
[0040] placing each of the first plurality of optical fibre ends
and the corresponding fibre of the second plurality of optical
fibre ends into a first and second connector housing, respectively,
such that cores of the first plurality of optical fibre ends and
the corresponding core of the second plurality of optical fibre
ends have a first orientation relative to each other;
[0041] simultaneously launching light through each of the first and
second plurality of optical fibres,
[0042] adjusting the relative orientation of the cores of each
fibre pair until a preferred coupling is obtained; and,
[0043] when a preferred coupling is obtained securing the
orientation of the fibre cores with respect to the key elements by
affixing the ferrules within the connector housings.
BRIEF DESCRIPTION OF FIGURES
[0044] Exemplary embodiments of the invention will now be described
in conjunction with the drawings, in which:
[0045] FIG. 1A is a transverse sectional view of a prior art,
single fibre connector prior to tuning;
[0046] FIG. 1B is a transverse sectional view of the connector of
FIG. 1A subsequent to tuning;
[0047] FIG. 2A is a transverse sectional view of a further prior
art single fibre connector prior to tuning;
[0048] FIG. 2B is a transverse sectional view of the connector of
FIG. 2A subsequent to tuning;
[0049] FIG. 3 is an isometric view of a prior art MACII multiple
optical fibre connector;
[0050] FIG. 4 is an isometric view of a further prior art multiple
optical fibre connector;
[0051] FIG. 5 is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention;
[0052] FIG. 5A is an isometric view of the connector of FIG. 5
comprising a colour code as a key element;
[0053] FIG. 5B is an isometric view of the connector of FIG. 5
comprising a pin and a hole as a key element;
[0054] FIG. 5C is an isometric view of the connector of FIG. 5
comprising an asymmetric housing as a key element;
[0055] FIG. 6A is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention
indicating a fibre core orientation;
[0056] FIG. 6B is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention
indicating a fibre core orientation;
[0057] FIG. 6C is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention
indicating a fibre core orientation;
[0058] FIG. 6D is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention
indicating a fibre core orientation;
[0059] FIG. 7A is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention wherein
each optical fibre is retained in a separate bore;
[0060] FIG. 7B is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention wherein
all optical fibres are retained in one bore;
[0061] FIG. 7C is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention wherein
a housing comprises several bores, each bore retaining several
optical fibres;
[0062] FIG. 8A illustrates a tuned multiple optical connector in
accordance with the present invention comprising male and female
connector housings;
[0063] FIG. 8B illustrates a tuned multiple optical connector in
accordance with the present invention comprising two connector
housings having a same shape mated together by a third intermediate
housing;
[0064] FIG. 8C illustrates a tuned multiple optical connector in
accordance with the present invention comprising two connector
housings having a same shape mated together;
[0065] FIG. 8D illustrates a tuned multiple optical connector in
accordance with the present invention comprising a first connector
housing mated with two connector housings;
[0066] FIG. 9A is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention, wherein
optical fibre ends are supported by a ferrule and the ferrule has a
flattened face for engaging with a side wall of a bore;
[0067] FIG. 9B is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention, wherein
optical fibre ends are supported by a ferrule and the ferrule has
grooves for engaging with a pin mounted within a bore;
[0068] FIG. 9C is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention, wherein
optical fibre ends are supported by a ferrule and the ferrule has
an octagonal collar for engaging with matching surfaces a bore;
[0069] FIG. 9D is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention, wherein
optical fibre ends are supported by a ferrule and the ferrule
retains a plurality of optical fibre ends; and,
[0070] FIG. 9E is a transverse sectional view of a tuned multiple
optical connector in accordance with the present invention, wherein
optical fibre ends are supported by a ferrule and a plurality of
ferrules are retained in a single bore.
DETAILED DESCRIPTION
[0071] FIGS. 1A and 1B show an optical fibre end 22 within a prior
art single tunable connector. The ferrule 8 supporting the fibre
end 22 is surrounded by an octagonal collar 20 having outer faces
21. The connector includes a positioning channel 3 for engaging the
faces 21 of the ferrule collar 20. The center of the ferrule 8 is
marked 23. It can be seen in FIG. 1A that the fibre end 22 is
positioned eccentrically. The eight faces of the collar 20 provide
eight rotational positions for placing the ferrule within the
connector. A position is chosen for most efficiently coupling the
fibre end to a connecting fibre end disposed within an associated
mating connector element.
[0072] FIGS. 2A and 2B show an alternative embodiment of the single
prior art connector. The outer collar 10 has twelve ridges and
depressions about the ferrule 8. As a result twelve positions
within the connector are possible, allowing greater flexibility to
the fibre positioning.
[0073] In modern communication networks a large amount of data is
transferred via fibre optic cables. Fibre optic cables usually
comprise a large number of individual optical fibres arranged, for
example, in a ribbon like structure. Using a single connector for
each fibre in order to connect two fibre optic cables is not a
practical solution. The cable has to be split into the individual
fibres a sufficient distance from the end so as to be able to
connect each fibre pair individually. Further, substantial space is
required for the large amount of connectors. This creates a large
amount of fibres that are no longer aligned, crossing each other in
different orientations. In such a confusing situation it is very
likely that the wrong fibres are connected to each other. Also,
maintenance and reliability are reduced because of the tangle of
fibres that results. Therefore, it is preferable to connect the
ends of two fibre optic cables with a single coupling.
[0074] FIGS. 3 and 4 illustrate prior art multiple connectors in
which exposed fibre ends 101 and 201 are aligned in precisely
machined locating plates. In both embodiments provision is made to
adjust horizontal or vertical positioning of all of the fibre ends
together to couple with an aligned additional set of fibre ends. No
tuning of individual fibres is possible. Consequently,
manufacturing irregularities such as variability in fibre diameter,
eccentricity of the fibre core or variability in the machining of
the plate cannot be compensated resulting in significant signal
loss with each fibre coupling.
[0075] FIG. 5 illustrates a transverse section through a multiple
optical connector 100 in accordance with the present invention. The
multiple optical connector 100 comprises a first housing 30A and a
second housing 30B. Each housing 30A, 30B comprises a plurality of
bores 34 for retaining the first and the second plurality of
optical fibre ends 22, respectively. Each of a plurality of optical
fibre ends 22 is retained in a bore 34 within the connector
housings 30A, 30B such that an optical fibre core 32 is in a plane
perpendicular to the longitudinal axis of the fibre above the
centre 38 of the bore 34 retaining the optical fibre end 22. In
such an arrangement, each fibre core 32 is oriented with respect to
a key element 36. The key elements 36 of the connector housings
30A, 30B are mating key elements for substantially limiting the
coupling of the two connector housings 30A, 30B to a single
orientation. When the connector housings 30A, 30B are coupled the
key elements 36 are disposed in a predetermined relation one to the
other. The core 32 of each optical fibre end 22 retained in the
first connector housing 30A is then substantially in alignment with
the core 32 of a corresponding optical fibre end 22 retained in the
second connector housing 30B. Key elements 36 are for example as
illustrated in FIGS. 5B to 5C: a pin 70 to fit in a hole 71 or
asymmetric connector housings 72A, 72B. Alternatively as shown in
FIG. 5A, the key element is other than a mating element, for
example a coloured mark 68.
[0076] Such a connector is manufactured by iteratively determining
the core orientation of each optical fibre end 22 with respect to a
reference point. When the core orientation is substantially the
predetermined core orientation the optical fibre end 22 is affixed
in the connector housing 30 such that the core 32 is oriented in a
predetermined fashion with respect to the key element 36 of the
connector housing 30. For example, the optical fibre ends 22 are
affixed in the connector housing 30 using an adhesive such as
epoxy. When the core orientation is other than the predetermined
orientation, the core orientation is altered.
[0077] Provision of fibre optic cables with tuned and standardised
multiple optical connectors, for example the fibre cores of all
connectors are oriented in a same fashion as illustrated in FIG. 5,
allows a user to connect fibre optic cables easily without a
significant signal loss.
[0078] FIGS. 6A to 6D illustrate numerous possibilities to arrange
the core orientation of the optical fibre ends 22 according to the
present invention. The illustration in FIG. 6A shows the cores 32
of the optical fibre ends 22 having different orientations -up,
right and down-. Such an arrangement of the fibre cores
necessitates two different connector housings 30A, 30B for
coupling, one being a mirror image of the other. In the arrangement
shown in FIG. 6B the cores 32 of all optical fibre ends 22 point to
one direction. Two connector housings 30A, 30B having such an
arrangement are mated by turning one connector housing upside down.
FIG. 6C shows the fibre cores 32 retained in the left half of the
connector housings 30A, 30B pointing to the left whereas the fibre
cores 32 retained in the right half of the connector housings 30A,
30B are pointing to the right. Two such connector housings 30A, 30B
are coupled either upside pointing to upside or one connector
housing turned upside down relative to the other. The arrangements
shown in FIGS. 5 and 6A to 6C are useful for different embodiments
of ribbon connectors. FIG. 6D shows an arrangement of optical
fibres 22 in a circular fashion, their cores 32 pointing from the
centre 33 of the circle outward. Such a connector allows coupling
of two connector housings 31A, 31B in as many positions as the
number of optical fibres 22 retained in the connector housings 31A,
31B by turning one housing about its centre 33. Of course, when a
single connector orientation is desired, a key for substantially
limiting connector coupling orientation is included within the
connector.
[0079] FIGS. 7A to 7C illustrate various arrangements of optical
fibre ends 22 retained in a connector housing 30 according to the
present invention. In FIG. 7A each of the optical fibre ends 22 is
retained separately in a bore 34. This embodiment is advantageous
for manufacturing because each fibre end 22 is oriented and affixed
separately. In the embodiment shown in FIG. 7B all optical fibre
ends 22 are retained in one bore 34. This arrangement of optical
fibres requires the smallest amount of space but is difficult to
manufacture because all fibres ends 22 are affixed at a same time.
FIG. 7C shows an arrangement of the optical fibre ends 22 wherein
the connector housing 30 comprises several bores 34 with each bore
34 retaining several fibre ends 22. Affixing the fibres is eased in
this embodiment due to a reduced number of fibres retained in a
single bore 34.
[0080] FIGS. 8A to 8D illustrate different embodiments of a
multiple fibre optic cable and connector assembly. Two push-pull
connector housings 30A, 30B join fibre ends from a first optical
cable 40 and a second optical cable 42. The individual optical
fibres are separated and stripped to expose the fibre ends 22 for
placement in the connector housings 30A, 30B. A sufficient length
of fibre is exposed to permit rotation of the fibre end through 180
degrees. Of course, a jacketed fibre is also rotatable and is
considered exposed as that term is used herein. The loose fibres
are provided with strain relief support elements and a covering
(not shown). In the embodiment shown in FIG. 8A, two connector
housings 30A, 30B of different shape to form a male and a female
part are mated to couple the ends of the two fibre optic cables 40
and 42. FIG. 8B shows two connector housings 30 of a same shape
mated by a third intermediate housing 30C. This embodiment allows
the use of fibre optic cables having a same connector housing 30 on
both ends and therefore provides more flexibility during an
installation of a network. These advantages are also provided by
the connector housings shown in FIG. 8C where both connector
housings 30 have a same shape, and do not need a third intermediate
housing for mating the two connector housings 30. FIG. 8D
illustrates a multiple optical connector assembly 200 wherein one
connector housing 30 is mated with two connector housings 50 and 52
to split one fibre optic cable 40 retaining a plurality of fibres
into two fibre optic cables 42 and 44 each retaining fewer fibres.
This is very useful for network applications where many parallel
optical fibres are needed, for example, at a central station
leading to different locations. Of course, such a connector
assembly is useful for splitting a fibre optic cable into any
number of fibre optic cables.
[0081] FIG. 9A illustrates a transverse section through another
embodiment of a multiple connector in accordance with the present
invention. Each optical fibre end 22 is supported by a ferrule 5,
and the ferrules 5 are positioned in individual bores 34 within the
connector housing 30, wherein each bore 34 has cross section in the
form of a quadratic cross section. A co-operative engagement
between the ferrule 5 and the bore 34 is provided. As shown in FIG.
9A the ferrule has a flattened face 6 for engaging one of the
sidewalls 19 of the bore 34. A close fit prevents the ferrule 5
from rotating in position. It is evident to those of skill in the
art that the term close fit relates to reasonable tolerances and
not necessarily to a tight fit. Tolerances are selected based on
design requirements and, as such, will vary. As shown, the ferrule
5 may be positioned with the engaging face 6 against any one of the
four sidewalls 19. In another embodiment shown in FIG. 9B the
ferrule 5 comprises etched grooves 62 in a circumferential
arrangement. Engaging one of the grooves 62 with a pin 60 in the
connector housing bore 34 prevents the ferrule 5 from rotating in
position. FIG. 9C shows another aligned connector assembly in
transverse section. Each of the ferrules 5 has an octagonal
surrounding collar 64 to engage matching angular surfaces 66 of the
connector housing bores 34. Optionally, a plurality of optical
fibres 22 are retained in one ferrule 5 as illustrated in FIG. 9D.
Further optionally, a plurality of ferrules 5 is retained in one
connector housing bore 34 as shown in FIG. 9E, wherein the ferrules
5 have, for example, a hexagonal cross section.
[0082] A connector housing wherein optical fibre ends are supported
by a ferrule 5 is manufactured by iteratively determining the core
orientation of each optical fibre end 22 with respect to a
reference point of the ferrule 5. When the core orientation is the
predetermined core orientation the optical fibre end is affixed in
the ferrule 5 such that the core of each of the optical fibre ends
is oriented in a predetermined fashion with respect to an indicator
element of the ferrule 5. Indicator elements are, for example, a
groove 62 or a flattened face 6. When the core orientation is other
than the predetermined orientation, the core orientation of the
optical fibre end 22 is altered. After the optical fibre 22 has
been affixed in the ferrule 5, the ferrule 5 is inserted into a
bore 34 of the connector housing 30 such that the key element of
the ferrule 5 is disposed in a predetermined relation to a key
element 36 of the connector housing 30. After insertion the ferrule
5 is affixed in the bore 34.
[0083] In another embodiment a multiple fibre optic connector for
connecting a first plurality of optical fibre ends 22 to a second
plurality of optical fibre ends 22 is tuned by mating a first
connector housing 30A with a second connector housing 30B such that
key elements 36 are disposed in a predetermined relation one to the
other indicating mating of the two connector housings 30A, 30B in
one and only one orientation. Then, each of the first plurality of
optical fibre ends 22 and the corresponding fibre end of the second
plurality of optical fibre ends 22 are placed into a first
connector housing 30A and second connector housing 30B,
respectively, such that cores of the first plurality of optical
fibre ends 22 and the corresponding core of the second plurality of
optical fibre ends 22 have a first orientation relative to each
other. Simultaneously light is launched through each of the first
and second plurality of optical fibres. The relative orientation of
the cores 32 of each fibre pair is adjusted until a preferred
coupling is obtained. When a preferred coupling is obtained the
orientation of the fibre cores 32 with respect to the key elements
36 is secured by affixing the fibres ends 22 within the connector
housings 30A, 30B.
[0084] Preferably, each optical fibre end is retained in a ferrule
5 for support. It is important to provide nearly concentric
rotation of the ferrule within the bore so that eccentricities in
the position of the fibre core are adjusted without introducing
additional change in position from the engaging between the ferrule
and the bore. Clearly, some error will occur in manufacture.
[0085] In a further embodiment, a connector according to the
invention is formed such that individual fibre alignments within
the multiple fibre connector are purposely skewed or offset by
individually adjusting particular connectors so as to provide a
preferred amount of attenuation between predetermined pairs. Hence,
the individual adjustability provides enhanced coupling between
individual pairs, or alternatively reduced coupling between
particular pairs. Such a connector is highly advantageous in
communication networks to equalise the signal intensity in parallel
optical fibres after an imbalanced switching device or filtering
process.
[0086] The invention disclosed herein provides a tuned multiple
optical connector by aligning cores of a plurality of optical fibre
ends with respect to a key element of a connector housing retaining
said optical fibre ends. Standardisation of the orientation of the
cores of the optical fibre ends provides multiple optical
connectors for connecting fibre optic cables without significant
signal loss or alternatively, with predetermined signal loss. It
further allows connection of any fibre optic cables comprising such
connectors without adjustment of core orientation during
installation.
[0087] A tunable multiple optical connector allowing tuning of
individual optical fibre alignments within the multiple optical
connector is disclosed. The connector provides a method of
individually tuning optical fibre alignment within such a connector
for correcting manufacturing irregularities and other imprecision
relating to connector construction and use. Of course, numerous
other embodiments may be envisaged, without departing from the
spirit and scope of the invention.
* * * * *