U.S. patent application number 14/500313 was filed with the patent office on 2016-03-31 for precision alignment of optical fiber ends along respective optical pathways in a multi-optical fiber connector module, and methods.
The applicant listed for this patent is Avago Technologies General IP (Singapore) Pte. Ltd.. Invention is credited to Laurence R. McColloch.
Application Number | 20160091672 14/500313 |
Document ID | / |
Family ID | 55410394 |
Filed Date | 2016-03-31 |
United States Patent
Application |
20160091672 |
Kind Code |
A1 |
McColloch; Laurence R. |
March 31, 2016 |
PRECISION ALIGNMENT OF OPTICAL FIBER ENDS ALONG RESPECTIVE OPTICAL
PATHWAYS IN A MULTI-OPTICAL FIBER CONNECTOR MODULE, AND METHODS
Abstract
An MF connector module is provided that positions the fiber end
portions relative to respective V-grooves of the module in such a
way that the fiber end portions can be bent, and thereby loaded, by
a predetermined amount when the fiber end portions are being
installed in the respective V-grooves. The bending of the fiber end
portions ensures that the optical axes of at least the tips of the
fiber end portions are parallel to the optical axes of the
respective V-grooves. The loading of the fiber end portions caused
by the bending ensures that significant lengths of the fiber end
portions are tangent to and in contact with the inner walls of the
respective V-grooves. This tangential contact between the fiber end
portions and the inner walls of the V-grooves causes the fiber end
faces to be precisely aligned with the respective optical axes of
the MF connector module.
Inventors: |
McColloch; Laurence R.;
(Santa Clara, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Avago Technologies General IP (Singapore) Pte. Ltd. |
Singapore |
|
SG |
|
|
Family ID: |
55410394 |
Appl. No.: |
14/500313 |
Filed: |
September 29, 2014 |
Current U.S.
Class: |
385/79 ; 29/428;
385/83 |
Current CPC
Class: |
G02B 6/3861 20130101;
G02B 6/3839 20130101; G02B 6/3898 20130101; G02B 6/32 20130101 |
International
Class: |
G02B 6/38 20060101
G02B006/38 |
Claims
1. A multi-optical fiber (MF) connector module comprising: a module
body comprising: a top side, a bottom side, a front end, a back
end, a left side, and a right side; a chamber formed in the top
side of the module body, the chamber having at least a front wall,
a bottom, a first side wall, and a second side wall; a ridge, or
corner, opposite the front wall of the chamber and extending in a
direction that is generally parallel to the front wall of the
chamber; an optics system disposed in or on the front wall of the
chamber; and a plurality of V-grooves formed in the bottom of the
chamber, each V-groove having a front end and a back end that is
opposite the front end, the front end of each V-groove being
proximate the optics system, the V-grooves having respective
optical axes that are parallel to one another and generally
perpendicular to the front wall of the chamber, wherein the ridge
is a greater distance from the bottom side of the module body than
the grooves are from the bottom side of the module body, and
wherein when a plurality of end portions of optical fibers are laid
in the chamber, rear locations on the fiber end portions are in
contact with the ridge and end faces of the optical fibers are
proximate respective V-grooves of the plurality of V-grooves.
2. The MF connector module of claim 1, wherein the difference in
the distances of the ridge and the V-grooves from the bottom side
of the module body causes the fiber end portions to slope
downwardly from the ridge toward the respective V-grooves.
3. The MF connector module of claim 2, wherein the optics system
comprises an array of lenses having respective optical axes that
are coaxially aligned with the respective optical axes of the
respective V-grooves.
4. The MF connector module of claim 3, wherein the difference in
the distances of the ridge and the V-grooves from the bottom side
of the module body allow predetermined amounts of bend to be formed
in the fiber end portions to ensure that when at least tips of the
fiber end portions are disposed within the respective V-grooves,
optical axes of the tips are coaxially aligned with the optical
axes of the respective lenses.
5. The MF connector module of claim 1, wherein the module body is a
unitary part comprising plastic.
6. The MF connector module of claim 5, wherein the ridge is
integrally formed in the module body.
7. The MF connector module of claim 5, further comprising at least
first and second mating features disposed on the front end of the
module body for mating with respective first and second mating
features of a parallel optical communications module for
mechanically and optically coupling the MF connector module with
the parallel optical communications module.
8. A multi-optical fiber (MF) connector module assembly comprising:
a module body comprising: a top side, a bottom side, a front end, a
back end, a left side, and a right side: a chamber formed in the
top side of the module body, the chamber having at least a front
wall, a bottom, a first side wall, and a second side wall; a ridge,
or corner, opposite the front wall of the chamber and extending in
a direction that is generally parallel to the front wall of the
chamber; an optics system disposed in or on the front wall of the
chamber; and a plurality of V-grooves formed in the bottom of the
chamber, each V-groove having a front end and a back end that is
opposite the front end, the front end of each V-groove being
proximate the optics system, the V-grooves having respective
optical axes that are parallel to one another and generally
perpendicular to the front wall of the chamber, wherein the ridge
is a greater distance from the bottom side of the module body than
the grooves are from the bottom side of the module body; and a
plurality of end portions of optical fibers disposed in the chamber
with at least tips of the fiber end portions disposed within the
respective V-grooves and rear locations on the fiber end portions
being in contact with the ridge, and wherein a predetermined amount
of bend, or curve, exists in each fiber end portion between the
tips and the rear locations on the fiber end portions that are in
contact with the ridge, the bend in each fiber end portion being
directed away from the top side of the module body toward the
bottom side of the module body, the bends set respective
predetermined loads on the respective fiber end portions and cause
the tips to properly sit in the respective V-grooves thereby
ensuring that optical axes of the tips are coaxially aligned with
the optical axes of the respective V-grooves, and wherein optical
axes of the tips are coaxially aligned with the optical axes of the
respective V-grooves.
9. The MF connector module assembly of claim 8, wherein the optics
system comprises an array of lenses having respective optical axes
that are coaxially aligned with the respective optical axes of the
respective V-grooves.
10. The MF connector module assembly of claim 9, wherein the module
body is a unitary part comprising plastic.
11. The MF connector module assembly of claim 10, wherein the ridge
is integrally formed in the module body.
12. The MF connector module assembly of claim 11, further
comprising at least first and second mating features disposed on
the front end of the module body for mating with respective first
and second mating features of a parallel optical communications
module for mechanically and optically coupling the MF connector
module with the parallel optical communications module.
13. A method for installing ends of optical fibers in a
multi-optical fiber (MF) connector module, the method comprising:
providing a module body comprising: a top side, a bottom side, a
front end, a back end, a left side, and a right side; a chamber
formed in the top side of the module body, the chamber having at
least a front wall, a bottom, a first side wall, and a second side
wall; a ridge, or corner, opposite the front wall of the chamber
and extending in a direction that is generally parallel to the
front wall of the chamber; an optics system disposed in or on the
front wall of the chamber; and a plurality of V-grooves formed in
the bottom of the chamber, each V-groove having a front end and a
back end that is opposite the front end, the front end of each
V-groove being proximate the optics system, the V-grooves having
respective optical axes that are parallel to one another and
generally perpendicular to the front wall of the chamber, wherein
the ridge is a greater distance from the bottom side of the module
body than the grooves are from the bottom side of the module body;
and disposing a plurality of end portions of optical fibers in the
chamber with at least tips of the fiber end portions disposed
within the respective V-grooves and rear locations on the fiber end
portions being in contact with the ridge, and wherein a
predetermined amount of bend, or curve, exists in each fiber end
portion between the tips and the rear locations on the fiber end
portions that are in contact with the ridge, the bend in each fiber
end portion being directed away from the top side of the module
body toward the bottom side of the module body, the bends set
respective predetermined loads on the respective fiber end portions
that cause the tips to properly sit in the respective V-grooves
thereby ensuring that optical axes of the tips are coaxially
aligned with the optical axes of the respective V-grooves.
14. The method of claim 13, wherein the optics system comprises an
array of lenses having respective optical axes that are coaxially
aligned with the respective optical axes of the respective
V-grooves.
15. The method of claim 14, wherein the module body is a unitary
part comprising plastic.
16. The method of claim 15, wherein the ridge is integrally formed
in the module body.
17. The method of claim 13, wherein the module body further
comprises at least first and second mating features disposed on the
front end of the module body for mating with respective first and
second mating features of a parallel optical communications module
for mechanically and optically coupling the MF connector module
with the parallel optical communications module.
18. The method of claim 13, wherein the step of disposing the fiber
end portions in the chamber is performed by a tool having a forming
punch that presses against the fiber end portions to dispose them
fiber end portions in the chamber such that rear locations on the
fiber end portions are in contact with the ridge and end faces of
the optical fibers are proximate respective V-grooves of the
plurality of V-grooves.
19. The method of claim 18, wherein the step of disposing at least
the tips in the respective V-grooves is performed by a tool having
a forming punch that is moved to a precise, predetermined location
relative to the module body to press against the fiber end portions
to thereby cause the predetermined amount of bend to be formed in
each of the fiber end portions and at least the tips to be seated
in the respective V-grooves and.
20. The method of claim 19, wherein the precise, predetermined
location to which the forming punch is moved is preselected to form
the predetermined amount of bend in each of the fiber end portions,
and wherein the predetermined amount of bend is preselected to
cause predetermined loads to be set on the respective fiber end
portions.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The invention relates to optical communications. More
particularly, the invention relates to a multi-optical fiber
connector module configured to ensure alignment of the ends of
optical fibers along respective optical axes of the module, and
methods.
BACKGROUND OF THE INVENTION
[0002] Multi-optical fiber (MF) connector modules are used to
mechanically couple the ends of a plurality of optical fibers to a
parallel optical communications module that has a plurality of
optical channels. The parallel optical communications module may be
a parallel optical transceiver module having both transmit and
receive optical channels, a parallel optical transmitter module
having only transmit optical channels, or a parallel optical
receiver module having only receive optical channels. A typical MF
connector module includes an optics system that couples light
between the ends of the optical fibers held in the MF connector
module and the parallel optical communications module. Within the
parallel optical communications module, an optics system couples
light between the MF connector module and a plurality of
optoelectronic devices disposed inside of the parallel optical
communications module. For transmit optical channels, the
optoelectronic devices are electrical-to-optical converters such as
laser diodes or light-emitting diodes (LEDs). For receive optical
channels, the optoelectronic devices are optical-to-electrical
converters such as P-intrinsic-N (PIN) photodiodes.
[0003] The MF connector modules and the parallel optical
communications modules typically have mating features on them that
allow them to be fixedly or removably mechanically coupled (i.e.,
mated) with one another. A variety of MF connector modules and
parallel optical communications modules exist in the market today
that are designed to mate with one another in a way that optically
aligns the optical pathways between the ends of the optical fibers
and the respective optoelectronic devices to enable optical data
signals to be efficiently optically coupled between ends of the
optical fibers and the respective optoelectronic devices. In
designing and manufacturing the MF connector modules and the
corresponding parallel optical communications modules, great care
is taken to ensure that once the modules are mated together, very
precise optical alignment exists along the optical pathways.
[0004] Inside of the MF connector module, the ends of the optical
fibers are typically held in alignment with respective lenses of
the optics system of the MF connector module. The lenses of the
connector module couple light between the ends of the optical
fibers and the optics system of the parallel optical communications
module, which often folds the optical pathways by some angle (e.g.,
90.degree.). However, the folding of the optical pathways is
sometimes performed by the optics system of the MF connector
module, or folding may be performed by each of the optics
systems.
[0005] The alignment of the optical pathways that extend between
the ends of the optical fibers, the optics system of the MF
connector module, the optics system of the parallel optical
communications module, and the optoelectronic devices of the
parallel optical communications module should be very precise in
order to ensure good optical coupling efficiency and good
performance. A variety of configurations exist for holding the ends
of the fibers in fixed, aligned positions within the MF connector
module. It is well known to use a V-groove configuration in the MF
connector module for holding the ends of the optical fibers in
fixed, aligned positions within the MF connector module. The ends
of the optical fibers are positioned in respective V-grooves and
then a refractive index matching epoxy is used to fix the ends in
position within the respective V-grooves. A cover is sometimes
placed over the V-grooves to protect the fiber ends and to help
hold them in position.
[0006] One potential problem with such V-groove configurations is
that the V-grooves do not always perfectly align the ends of the
respective fibers with the lenses of the MF module. This is because
the optical fibers do not always conform to the V-grooves. The
optical fibers tend to act like rigid rods in the V-grooves in that
misalignment of the fiber at the back of the V-groove will result
in misalignment of the fiber at the front of the V-groove. For
example, if the fiber has ridden up the edge of the respective
V-groove at the back of the V-groove, it will usually also ride up
the edge of the V-groove in the front of the V-groove. In addition,
optical fibers of an optical fiber ribbon cable are not always
parallel to one another in all planes once the fibers have been
freed from the cable and stripped of their jackets. Fibers in a
ribbon cable have a "set," which means that when freed from the
cable and stripped of their jackets, they curl in multiple
directions and are not all parallel in all planes. The fiber "set"
makes it difficult to achieve the needed micron-level alignment
accuracy of the fiber ends with their respective lenses.
[0007] Moreover, if the V-grooves are formed in plastic, the
V-grooves may deform in the areas where a load is applied when the
fibers are pressed into them. This can cause the front portion of
the fiber end (end portion nearest to the lenses) to lift upwards
away from the V-groove, even if the deformation is within the
elastic stress range of the plastic. This upward lifting of the
fiber end in combination with the "set" problem can mean that a
different force is acting on each fiber due to its unique set,
which can cause the V-grooves to deform by unique amounts for each
fiber. This, in turn, can result in a unique alignment error for
each fiber.
[0008] A need exists for an MF connector module and methods that
enable ends of optical fibers to be installed and held in an MF
connector module in precise alignment with respective optical axes
of the module.
SUMMARY OF THE INVENTION
[0009] The invention is directed to an MF connector module, an MF
connector module assembly, and a method. The MF connector module
comprises a module body comprising a top side, a bottom side, a
front end, a back end, a left side, a right side, a chamber formed
in the top side of the module body, a ridge, or corner, an optics
system, and a plurality of V-grooves. The chamber has at least a
front wall, a bottom, a first side wall, and a second side wall.
The ridge, or corner, is opposite the front wall of the chamber and
extends in a direction that is generally parallel to the front wall
of the chamber. The optics system is disposed in or on the front
wall of the chamber. The V-grooves are formed in the bottom of the
chamber. Each V-groove has a front end and a back end that is
opposite the front end. The front end of each V-groove is proximate
the optics system. The V-grooves have respective optical axes that
are parallel to one another and generally perpendicular to the
front wall of the chamber. The ridge is a greater distance from the
bottom side of the module body than the grooves are from the bottom
side of the module body. When a plurality of end portions of
optical fibers are laid in the chamber, rear locations on the fiber
end portions are in contact with the ridge and end faces of the
optical fibers are proximate respective V-grooves.
[0010] The MF connector module assembly comprises the MF connector
module and a plurality of end portions of optical fibers disposed
in the chamber with at least tips of the fiber end portions
disposed within the respective V-grooves and rear locations on the
fiber end portions in contact with the ridge. A predetermined
amount of bend, or curve, exists in each fiber end portion between
the tips and the rear locations on the fiber end portions that are
in contact with the ridge. The bend in each fiber end portion is
directed away from the top side of the module body toward the
bottom side of the module body. The bends preload the fiber end
portions, which causes the tips to properly sit in the respective
V-grooves thereby ensuring that optical axes of the tips are
coaxially aligned with the optical axes of the respective
V-grooves.
[0011] The method comprises providing the MF connector module and
disposing a plurality of end portions of optical fibers in the
chamber with at least tips of the fiber end portions disposed
within the respective V-grooves and rear locations on the fiber end
portions being in contact with the ridge. A predetermined amount of
bend, or curve, exists in each fiber end portion between the tips
and the rear locations on the fiber end portions that are in
contact with the ridge. The bend in each fiber end portion is
directed away from the top side of the module body toward the
bottom side of the module body. The bends preload the fiber end
portions, which causes the tips to properly sit in the respective
V-grooves thereby ensuring that optical axes of the tips are
coaxially aligned with the optical axes of the respective
V-grooves.
[0012] These and other features and advantages of the invention
will become apparent from the following description, drawings and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A illustrates a top perspective view of the MF
connector module in accordance with an illustrative embodiment.
[0014] FIG. 1B illustrates a perspective cross-sectional view of
the MF connector module shown in FIG. 1A taken along line A-A'.
[0015] FIG. 2 illustrates a perspective view of a tool that may be
used to hold the MF connector module shown in FIGS. 1A and 1B and
to apply a force to the fiber end portions to install them in the
respective V-grooves of the MF connector module.
[0016] FIG. 3 illustrates an expanded cross-sectional view of a
portion of the view shown in FIG. 2.
[0017] FIGS. 4A-4C illustrate side cross-sectional views of the MF
connector module shown in FIGS. 1A and 1B in different stages of
installment of the fiber end portions in the V-grooves of the MF
connector module.
[0018] FIG. 5 illustrates a flow diagram of the method in
accordance with an illustrative embodiment for installing the fiber
end portions in the chamber of the MF connector module.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
[0019] In accordance with illustrative, or exemplary, embodiments
of the invention, an MF connector module is provided that has a
configuration that positions the fiber end portions relative to
respective V-grooves of the module in such a way that the fiber end
portions can be bent, and thereby loaded, by a predetermined amount
when the fiber end portions are being installed in the respective
V-grooves. The bending of the fiber end portions ensures that the
optical axes of at least the tips of the fiber end portions are
parallel to the optical axes of the respective V-grooves. The
loading of the fiber end portions caused by the bending ensures
that significant lengths of the fiber end portions are tangent to
and in contact with the inner walls of the respective V-grooves.
This tangential contact between the fiber end portions and the
inner walls of the respective V-grooves causes the fiber end faces
to be precisely aligned with the respective optical axes of the MF
connector module. Illustrative embodiments of the MF connector
module and of the installation method will now be described with
reference to FIGS. 1A-5, in which like reference numerals represent
like elements, features or components. It should be noted that
elements, features or components in the figures are not necessarily
drawn to scale.
[0020] FIG. 1A illustrates a top perspective view of the MF
connector module 1 in accordance with an illustrative embodiment.
FIG. 1B illustrates a perspective cross-sectional view of the MF
connector module 1 shown in FIG. 1A taken along line A-A'. The MF
connector module 1 comprises a module body 2 having an upper
surface 2a, a lower surface 2b, a front surface 2c, and a back
surface 2d. A cavity 3 is formed in the upper surface 2a and
extends a distance in the Y-direction of an X, Y, Z Cartesian
coordinate system into the module body 2. The chamber 3 is
configured to receive and hold end portions 4a of N optical fibers
4, where N is a positive integer that is equal to or greater than
2. For purposes of clarity, a single optical fiber 4 is shown in
FIGS. 1A and 1B. In accordance with this illustrative embodiment,
N=16, and thus the MF connector module 1 has sixteen respective
optical pathways and sixteen respective optical axes. It should be
noted, however, that the invention is not limited with respect to
the number of optical fibers that are connected to the MF connector
module 1 or with respect to the number of optical channels that are
provided in the MF connector module 1.
[0021] The module body 2 is typically a molded, unitary plastic
part, although the invention is not limited with respect to the
material of which the module body 2 is made or with respect to the
number of piece parts that are joined together to make the module
body 2. The module body 2 has male mating features 5a and 5b
extending from its front surface 2c for mating with
complementarily-shaped holes (not shown) formed in a body of a
parallel optical communications module (not shown) with which the
MF connector module 1 is designed to mate. In accordance with this
illustrative embodiment, the front surface 2c has a set-back region
6 (FIG. 1B) formed therein within which an optics system 7 (FIG.
1B) of the module 1 is disposed. The optics system 7 comprises a
linear array of N lenses 7a (FIG. 1B), each corresponding to one of
N optical axes 9 of the MF connector module 1.
[0022] When the end portions 4a of the optical fibers 4 are fixedly
positioned in the chamber 3, the end portions 4a need to be
precisely aligned with the respective optical axes 9 of the
respective lenses 7a. The manner in which the configuration of the
MF connector module 1 ensures such precise alignment will be
described below in detail. The cavity 3 functions as a holding
chamber for holding the end portions 4a of the optical fibers 4.
The cavity 3 has a lower surface 3a in which a plurality of
V-grooves 8 are formed. The V-grooves 8 extend parallel to the Z
axis of the X, Y, Z Cartesian Coordinate system shown in FIGS. 1A
and 1B. Each V-groove 8 is precisely aligned with a respective lens
7a, and thus the optical axes 8 of the lenses 7a correspond to
respective optical axes of the V-grooves 8.
[0023] As can best be seen in FIG. 1B, a ridge, or corner, 10
extends across the chamber 3 in the X-direction near the back of
the chamber 3. In other words, the ridge 10 is transverse to the
optical axes of the V-grooves 8. The ridge 10 is above the
V-grooves 8 in the Y-dimension, i.e., the ridge apex 10a has a Y
coordinate that is greater than the Y coordinate of the V-grooves
8. When the fiber end portions 4a are laid in the chamber 3, the
locations where the end portions 4a rest on the ridge 10 are above
(the positive Y direction) the locations where the end portions 4a
rest on or are suspended just above the V-grooves 8. This is
important because it allows a force to be applied to the fiber end
portions 4a to bend them by preselected amounts in order to
pre-load them during the installation process, as will be described
below in more detail.
[0024] In FIG. 1B, it can be seen that when the end portion 4a of
the fiber 4 is fully installed in its respective V-groove 8, the
outer surface of the fiber end portion 4a is in tangential contact
with the V-groove 8 along the entire length, or nearly the entire
length, of the V-groove 8. As indicated above, this continuous or
nearly continuous tangential contact between the fiber end portion
4a and the respective V-groove 8 causes the fiber end face 4b to be
precisely aligned with the respective optical axis 8 of the
respective lens 7a of the MF connector module 1. As will be
described below in more detail with reference to FIGS. 2 and 3,
each fiber end portion 4a is installed in its respective V-groove 8
by using a tool (not shown) that forms a preselected amount of bend
in the fiber end portions 4a in between the fiber end faces 4b and
the location on the fiber end portions 4a that come into contact
with the ridge 10. Arrow 11 in FIG. 1B represents the direction of
movement of the tool (not shown) against the fiber end portions 4a
to form the preselected amount of bend in the fiber end portions
4a. This bending, or shaping, of the fiber end portions 4a loads
them such that they exert a well-controlled force against the
respective V-grooves 8, which ensures that the outer surfaces of at
least the tips of the fiber end portions 4a are in tangential
contact with the respective V-groove 8. This, in turn, ensures that
the end faces 4b of the fibers 4 are precisely aligned with the
respective lenses 7a along the respective optical axes 8.
[0025] FIG. 2 illustrates a perspective view of a tool 20 being
used to hold the MF connector module 1 shown in FIGS. 1A and 1B as
a forming punch 22 of the tool 20 presses against the fiber end
portions 4a in the direction represented by arrow 11 to form the
preselected bends in the fiber end portions 4a and install them in
the respective V-grooves 8 (FIGS. 1A and 1B) of the MF connector
module 1. FIG. 3 illustrates an expanded cross-sectional view of
the portion of the view shown in the circle labeled with reference
numeral 21 in FIG. 2. The forming punch 22 moves a very precise
distance relative to the module 1 in the Y-direction represented by
arrow 11 to press the fiber end portions 4a against the V-grooves 8
and against the ridge 10 until a predetermined amount of bend has
been formed in the fiber end portions 4a. As indicated above, the
predetermined amount of bend formed in the fiber end portions 4a
loads them with predetermined amounts of force. The tool 20 is
designed and manufactured to control the Y positioning of the punch
22 with an accuracy of within 1.0 micrometers (microns). This
enables the fiber end portions 4a to be bent or curved by very
small amounts to shape the end portions 4a resulting in very small,
predetermined, uniform loads. For example, the loads that are
placed on the end portions 4a may be on the order of one-one
thousandth of a pound (lb), or 0.004 Newtons. These loads on the
fiber end portions 4a hold them in the respective V-grooves 8,
thereby ensuring that the end faces 4b of the fiber end portions 4a
are precisely aligned with the respective lenses 7a (FIG. 1B).
[0026] FIGS. 4A-4C illustrate side cross-sectional views of the MF
connector module 1 in different stages of installment of the fiber
end portions 4a in the V-grooves 8. FIG. 4A depicts the fiber
installment stage when the fiber end portions 4a have been laid in
the chamber 3 such that locations on the fiber end portions 4a near
the back surface 2d of the module 1 are in contact with the ridge
10 and the end faces 4b of the fiber end portions 4a are suspended
just above the respective V-grooves 8. FIG. 4B depicts the fiber
installment stage when forming punch 22 has moved against the fiber
end portions 4a causing the tips 4c of the fiber end portions 4a to
come into contact with forward portions of the V-grooves 8 and
causing the locations on the fiber end portions 4a near the back
surface 2d of the module 1 to come into contact with the ridge 10
to form the predetermined amount of bend in the fiber end portions
4a. FIG. 4C depicts the fiber installment stage when continued
movement of the forming punch 22 against the fiber end portions 4a
has placed them in tangential contact with the respective V-grooves
8 along the entire, or nearly the entire, lengths of the V-grooves
8.
[0027] In FIG. 4B, the dashed lines 25 represent the shape of the
fiber end portions 4a during the fiber installation stage shown in
FIG. 4A. It can be seen in FIG. 4B that when the fiber end portions
4a are bent by moving the punch 22 by a predetermined amount in the
Y-direction indicated by arrow 24, the optical axes 26 of at least
the tips 4c of the fiber end portions 4a are parallel to the
optical axes 27 of the V-grooves 8. The tips 4c are defined as a
portion of the fiber end portions 4a starting at the end faces 4b
and extending a distance, d, away from the end faces 4b along the
lengths of the fiber end portions 4a, where d is less than the
length, 1, of the V-grooves 8. As indicated above, the optical axes
27 of the V-grooves 8 correspond to the optical axes of the
respective lenses 7a (FIG. 1B). Therefore, the bend formed by the
punch 22 in the fiber end portions 4a does not cause the fiber end
faces 4b to be directed upwardly away from the respective V-grooves
8. The bends formed in the fiber end portions 4a uses the stiffness
inherent to the fibers 4 to create the appropriate individual loads
needed for the respective fibers 4. This stiffness in the fiber end
portions 4a causes the optical axes 26 of at least the tips 4c of
the fiber end portions 4a to remain parallel to the optical axes 27
of the V-grooves 8 throughout the installation process.
[0028] The movement of the punch 22 to a predetermined location
forces a shape (i.e., a bend) in the fiber end portions 4a that is
determined by the contact of the fiber end portions 4a with the
respective V-grooves 8, the forming punch 22 and the ridge, or
corner, 10. That shape can range from where just the fiber tip 4c
is in contact with the V-groove 8 to where the fiber end portion 4a
is in tangential contact with the inner surfaces of the V-groove 8
along the entire length of the V-groove 8. As long as at least the
tip 4c is in tangential contact with the V-groove 8, the optical
axis 26 of at least the tip 4c is coaxial with the optical axis 27
of the V-groove 8. This coaxial arrangement ensures precise optical
alignment of the fiber end portions 4a with the respective lenses
7a.
[0029] This also provides some tolerance for movement of the punch
22 during the installation process to allow misalignment to be
avoided. If the punch 22 were to be moved in the direction
indicated by arrow 24 beyond the point at which the fiber end
portion 4a is in tangential contact with the V-groove 8 along the
entire length of the V-groove 8, the end faces 4b would be directed
upwardly and the tips 4c would not be aligned with the respective
lenses 7a. As long as the positioning of the punch 22 is such that
at least the tip 4c is in tangential contact with the V-groove and
no more than the entire length of the V-groove 8 being in contact
with the fiber end portion 4a, precise optical alignment is
achieved. This also prevents the V-grooves 8 from being damaged by
excessive force of the fiber end portions 4a against the V-grooves
8. Therefore, while FIG. 4C depicts the fiber end portion 4a being
in tangential contact with the V-groove 8 along the entire length
of the V-groove 8, this is not required to achieve precise optical
alignment between the fiber end faces 4b and the respective lenses
7a.
[0030] Once the fiber end portions 4a have been installed in the
respective V-grooves 8, an epoxy (not shown) is placed in the
chamber 3 beneath the fiber end portions 4a. The epoxy wicks
upwardly in between the fiber end portions 4a and into the
V-grooves 8, but does not come into contact with the punch 22. The
epoxy secures the end portions 4a to the respective V-grooves 8.
The epoxy is transparent to the operating wavelength of light that
is used with the MF connector module 1 and with the mating parallel
optical communications module (not shown). A cover (not shown) that
covers and protects the end portions 4a may be secured to the
chamber 3 by the epoxy or by some other mechanism. With this
design, the punch 22 remains above the fiber end portions 4a so
that it is not glued into the final assembly.
[0031] FIG. 5 illustrates a flow diagram of the method in
accordance with an illustrative embodiment for installing the fiber
end portions 4a in the chamber 3 of the MF connector module 1. The
fiber end portions are first laid in the chamber of the MF
connector module such that each fiber end portion is in contact
with the ridge located near the back of the chamber and the tips of
the fiber end portions are disposed proximate the respective
V-grooves, as indicated by block 41. As indicated above, the ridge
is above the V-grooves in the Y-direction, which provides space
beneath the fiber end portions to allow them to be bent to set
loads on them. The forming punch is then moved in the Y-direction
toward locations on the fiber end portions in between the ridge and
the V-grooves until the punch makes contact with the fiber end
portions, as indicated by block 42. After the forming punch makes
contact with the fiber end portions, the forming punch is moved to
a precise, predetermined location to form a predetermined amount of
bend in the fiber end portions and to move at least the tips of the
fiber end portions into contact with the inner walls of the
respective V-grooves. This step is represented by block 43.
[0032] As indicated above, the bend that is formed in each fiber
end portions is such that the optical axes of at least the tips of
the fiber end portions are parallel to the optical axes of the
V-grooves. In other words, the tips of the fiber end portions are
not angled upwardly away from the V-grooves. This ensures that when
the fiber end portions come into contact with the respective
V-grooves, at least the tips of the fiber end portions will be in
tangential contact with the respective V-grooves. Once the fiber
end portions have been installed in the respective V-grooves in
this manner, the fiber end portions are then secured to the
respective V-grooves and the punch is withdrawn so that it is no
longer in contact with the fiber end portions, as indicated by
block 44. As indicated above, this is typically accomplished by
using epoxy that is transparent to the operating wavelength,
although other mechanisms could be used for this purpose.
[0033] The ridge, or corner, 10, the punch 22 and the tangent of
the V-grooves 8 determine the shape of the bent fiber end portions
4a. The shape, in turn, sets the load that forces the fiber end
portions to sit correctly in the respective V-grooves 8. Thus, the
relative positions of these features with respect to one another
and with respect to the fiber end portions 4a are important.
However, the punch 22 can make contact with the fiber end portions
at different locations between the end faces 4b and the locations
on the fiber end portions 4a that come into contact with the ridge
10. The ridge 10 is essentially a stop or pivot point. This
function could be performed by virtually any feature capable of
performing the function. Such a feature may be integrally formed in
the module body 2 or it may be a separate component, element or
device that is secured to the module body 2 at the proper location
and with the proper orientation.
[0034] It should be noted that the invention has been described
with reference to illustrative, or exemplary, embodiments in order
to demonstrate the principles and concepts of the invention. As
will be understood by those of skill in the art, the invention is
not limited to the illustrative embodiments described herein. For
example, the MF connector module 1 is an example of an MF connector
module that may be configured with the ridge to allow a pre-loading
bend of a predetermined amount to be formed in the fiber end
portions. Persons skilled in the art will understand, in view of
the description provided herein, that a variety of MF connector
modules having various configurations can be provided with such a
ridge and used with the method to install fiber end portions in
V-grooves to achieve the benefits described above. Persons skilled
in the art will understand the manner in which these and other
modifications may be made to the embodiments described herein and
that all such modifications are within the scope of the
invention.
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