U.S. patent application number 14/211480 was filed with the patent office on 2016-09-29 for unitary multi-fiber optical ferrule with integrated lenses.
The applicant listed for this patent is US Conec, Ltd.. Invention is credited to Darrell R. Childers, Michael E. Hughes.
Application Number | 20160282565 14/211480 |
Document ID | / |
Family ID | 56975357 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160282565 |
Kind Code |
A1 |
Childers; Darrell R. ; et
al. |
September 29, 2016 |
Unitary Multi-Fiber Optical Ferrule with Integrated Lenses
Abstract
A unitary multi-fiber ferrule has micro-holes for optical
fibers, and a plurality of lenses disposed adjacent the front end,
each of the plurality of lenses optically aligned with one of the
micro-holes and exposed to air. Multiple rows of optical fibers and
lenses may also be used in the unitary multi-fiber ferrule. The
lenses have a divergence half angle of between about 2 and 20
degrees and may also have protrusions on them acting as an
antireflective coating.
Inventors: |
Childers; Darrell R.;
(Hickory, NC) ; Hughes; Michael E.; (Hickory,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
US Conec, Ltd. |
Hickory |
NC |
US |
|
|
Family ID: |
56975357 |
Appl. No.: |
14/211480 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12907644 |
Oct 19, 2010 |
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14211480 |
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61789427 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/3853 20130101;
G02B 6/3831 20130101; G02B 6/32 20130101; G02B 6/403 20130101; G02B
6/3861 20130101; G02B 1/118 20130101; G02B 6/3885 20130101 |
International
Class: |
G02B 6/38 20060101
G02B006/38 |
Claims
1. A unitary fiber optic ferrule comprising: a unitary main body
having a front end, a back end, and a middle portion disposed
between the front end and back end; a first opening adjacent the
back end of the unitary main body, the first opening configured to
receive at least two optical fibers; a plurality of optical fiber
openings extending from the first opening toward the front end,
each of the plurality of optical fiber openings configured to
receive an optical fiber; and a plurality of lenses disposed
adjacent the front end, each of the plurality of lenses being in
optical alignment with a respective one of the optical fiber
openings, the plurality of lenses having at least one surface
exposed to air and each of the plurality of lenses having a
divergence half angle of between about 2 and 20 degrees.
2. The unitary fiber optic ferrule according to claim 1, wherein
the divergence half angle is larger than 2 degrees.
3. The unitary fiber optic ferrule according to claim 1, wherein
the divergence half angle is about 5 degrees.
4. The unitary fiber optic ferrule according to claim 1, further
comprising a recessed portion directly adjacent the front end, the
plurality of lenses disposed in the recessed portion.
5. The unitary fiber optic ferrule according to claim 3, wherein
the plurality of lenses have an apex and the apex of each of the
plurality of lenses is between 50 and 200 microns from the front
end of the unitary main body.
6. The unitary fiber optic ferrule according to claim 5, wherein
the apex of each of the plurality of lenses is about 50 microns
from the front end of the unitary main body.
7-13. (canceled)
14. A unitary fiber optic ferrule comprising: a unitary main body
having a front end, a back end, and a middle portion disposed
between the front end and back end; a first opening adjacent the
back end of the unitary main body, the first opening configured to
receive at least 12 optical fibers; a plurality of optical fiber
openings extending from the first opening toward the front end,
each of the plurality of optical fiber openings configured to
receive an optical fiber, the plurality of optical fiber openings
comprising at least two rows; and a plurality of lenses disposed
adjacent the front end and in at least two rows, each of the
plurality of lenses being in optical alignment with a respective
one of the optical fiber openings, the plurality of lenses having
at least one surface exposed to air and each of the plurality of
lenses having a divergence half angle of between about 2 and 20
degrees.
15. The unitary fiber optic ferrule according to claim 14, wherein
each of the at least two rows of optical fiber openings and the
plurality of lenses comprise three rows.
16. A unitary fiber optic ferrule comprising: a unitary main body
having a front end, a back end, and a middle portion disposed
between the front end and back end, the front end terminating at a
front face; a first opening adjacent the back end of the unitary
main body, the first opening configured to receive at least two
optical fibers; a plurality of optical fiber openings extending
from the first opening toward the front end, each of the plurality
of optical fiber openings configured to receive an optical fiber;
and a plurality of lenses disposed adjacent the front end, each of
the plurality of lenses being in optical alignment with a
respective one of the optical fiber openings, the plurality of
lenses having at least one surface exposed to air, the plurality of
lenses have a divergence half angle of between about 2 and 20
degrees and are disposed within a recessed portion directly
adjacent the front end and the front end circumscribing the
recessed portion.
Description
REFERENCE TO RELATED CASE
[0001] This application is a continuation in part of application
Ser. No. 12/907,644 filed Oct. 19, 2010, and also claims priority
under 35 U.S.C. .sctn.119 (e) to provisional application No.
61/789,427 filed on Mar. 15, 2013, the contents of both
applications are hereby incorporated by reference in their
entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] Typically, optical fibers inserted in optical ferrules,
particularly MT ferrules, need a significant amount of processing
for the optical ferrules to be able to efficiently transmit the
light through the optical fibers and across a fiber optic junction.
Optical fibers are inserted into the ferrules and then epoxy is
injected into the ferrules to secure the fibers in the ferrules.
The ferrules are then placed in curing oven for about 30 minutes to
cure the epoxy. After the epoxy is cured, the ferrules are polished
and cleaned at least four times using a fiber optic polishing
machine The visual quality of the optical fiber end face is
examined and the ferrules are re-polished if there are significant
scratches or pits. The end face geometry is also usually measured
with an interferometer and re-polished if there are issues with the
end face quality. Lastly, an optical test is completed. This
process requires a significant capital outlay for the equipment as
well as significant time and operator intervention to achieve a
quality product.
[0003] Additionally, the integrated lenses have a divergence half
angle .THETA. that is between about 2 and 20 degrees. Most
preferably, the divergence half angle .THETA. is about 5 degrees.
With this divergence half angle, the size of the light spot from
the ferrule expands from 0.18 mm to more than 4.5 mm at a position
25 mm away from the ferrule when put into service. This greatly
reduces the intensity of the light emitted from the ferrule at that
distance and reduces the potential damage done to a person's eye
working around the ferrules, making this a safety feature of the
ferrules.
[0004] The lenses may also have increased losses as a result of
using the integrated lenses. The losses are due to reflection of
the light of the curved surfaces. Using a plurality of protrusions
molded onto the surfaces of the lenses, reduces the reflections and
the losses associated therewith. The protrusions preferably do not
have a dimension that is the same as or greater than the wavelength
of the light passing through the lenses.
[0005] While providing an excellent fiber optic connector, a
cheaper optical ferrule that can be more efficiently assembled
without the expensive equipment is needed.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a unitary multi-fiber
optical ferrule that has rounded holes in the body of the ferrule
to accept and guide the optical fibers and integrated lenses that
can either collimate or focus the light for optical communication
with another optical ferrule, the lenses having a particular
divergence half angle.
[0007] According to one aspect of the present invention, a unitary
fiber optic ferrule includes a unitary main body having a front
end, a back end, and a middle portion disposed between the front
end and back end, a first opening adjacent the back end of the
unitary main body, the first opening configured to receive at least
two optical fibers, a plurality of optical fiber openings extending
from the first opening toward the front end, each of the plurality
of optical fiber openings configured to receive an optical fiber,
and a plurality of lenses disposed adjacent the front end, each of
the plurality of lenses being in optical alignment with a
respective one of the optical fiber openings, the plurality of
lenses having at least one surface exposed to air and each of the
plurality of lenses having a divergence half angle of between about
2 and 20 degrees.
[0008] In yet another aspect, a unitary fiber optic ferrule
includes a unitary main body having a front end, a back end, and a
middle portion disposed between the front end and back end, a first
opening adjacent the back end of the unitary main body, the first
opening configured to receive at least two optical fibers, a
plurality of optical fiber openings extending from the first
opening toward the front end, each of the plurality of optical
fiber openings configured to receive an optical fiber, and a
plurality of lenses disposed adjacent the front end, each of the
plurality of lenses being in optical alignment with a respective
one of the optical fiber openings, the plurality of lenses having
at least one surface exposed to air and having a plurality of
protrusions, each of the protrusions having dimensions smaller than
wavelengths of light passing through the unitary fiber optic
ferrule.
[0009] Additional features and advantages of the invention will be
set forth in the detailed description which follows, and in part
will be readily apparent to those skilled in the art from that
description or recognized by practicing the invention as described
herein, including the detailed description which follows, the
claims, as well as the appended drawings.
[0010] It is to be understood that both the foregoing general
description and the following detailed description of the present
embodiments of the invention, and are intended to provide an
overview or framework for understanding the nature and character of
the invention as it is claimed. The accompanying drawings are
included to provide a further understanding of the invention, and
are incorporated into and constitute a part of this specification.
The drawings illustrate various embodiments of the invention and,
together with the description, serve to explain the principles and
operations of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a top perspective view of one embodiment of a
unitary multi-fiber optical ferrule with integrated lenses
according to the present invention;
[0012] FIG. 2 is a front perspective view of the unitary
multi-fiber optical ferrule with integrated lenses of FIG. 1;
[0013] FIG. 3 is a top view of the unitary multi-fiber optical
ferrule with integrated lenses of FIG. 1;
[0014] FIG. 4 is a cross-sectional view of the unitary multi-fiber
optical ferrule with integrated lenses along the line A-A of FIG.
3;
[0015] FIG. 5 is a front elevational view of the unitary
multi-fiber optical ferrule with integrated lenses of FIG. 1;
[0016] FIG. 6 is a rear elevational view of the unitary multi-fiber
optical ferrule with integrated lenses of FIG. 1;
[0017] FIG. 7 is a perspective view of the unitary multi-fiber
optical ferrule with integrated lenses of FIG. 1 with optical
fibers in a ribbon configuration inserted therein;
[0018] FIG. 8 is a front perspective view of another embodiment of
a unitary multi-fiber optical ferrule with integrated lenses
according to the present invention;
[0019] FIG. 9 is a cross-sectional view of another embodiment of a
unitary multi-fiber optical ferrule with integrated lenses
according to the present invention;
[0020] FIG. 10 is a top perspective view of another embodiment of a
unitary multi-fiber optical ferrule with integrated lenses
according to the present invention;
[0021] FIG. 11 is a cross-sectional view of the unitary multi-fiber
optical ferrule with integrated lenses of FIG. 10;
[0022] FIG. 12 is an enlarged perspective view of the end face of
the multi-fiber optical ferrule of FIG. 10;
[0023] FIG. 13 is an enlarged view of a cross section at the front
end of the multi-fiber optical ferrule of FIG. 10;
[0024] FIGS. 14-16 are schematic representations of light passing
through lenses of a fiber optic ferrule;
[0025] FIG. 17 is an enlarged view of two multi-fiber optical
ferrules of FIG. 10 engaged with one another; and
[0026] FIG. 18 is a cross-section of a representative sample of the
protrusions on lenses of the multi-fiber optical ferrule.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Reference will now be made in detail to the present
preferred embodiment(s) of the invention, examples of which are
illustrated in the accompanying drawings. Whenever possible, the
same reference numerals will be used throughout the drawings to
refer to the same or like parts.
[0028] Referring to FIG. 1, a unitary multi-fiber optical ferrule
with integrated lenses 10 (optical ferrule) according to the
present invention is illustrated. The optical ferrule 10 preferably
has an front end 12, a back end 14, and a middle portion 16
disposed between the front end 12 and the back end 14. The optical
ferrule 10 is a unitary ferrule, that is, a single integral element
that is preferably molded at the same time from a homogeneous
material. The optical ferrule 10 is an optically clear polymer,
which may include polyetherimide, polycarbonate, cyclic olefin
copolymer, cyclic olefin polymer, or other transparent polymers.
The optical ferrule 10 has a first opening 18 adjacent the back end
14 to receive optical fibers therein. The optical ferrule 10 may
also have an opening 20 from the top surface 22 of the optical
ferrule 10 that is in communication with the first opening 18 to
inject epoxy to secure optical fibers within the optical ferrule 10
as described in more detail below. A plurality of micro-holes 24
extend through the middle portion 16 to hold and position optical
fibers inserted into the first opening 18. The micro-holes 24 are
preferably tapered, being larger adjacent the first opening 18 than
at the opposite end. A fiber stop plane 28 is disposed across an
opening 30 from the plurality of micro-holes 24. Preferably, the
opening 30 opens to one of the sides of the optical ferrule 10,
which is the top side 22 in this embodiment of optical ferrule 10.
Epoxy may also be injected into the opening 30 to further secure
the optical fibers in the optical ferrule 10. Preferably, the epoxy
used in the opening 30 and the first opening 18 is an index-matched
epoxy that is also preferably light curable. The fiber stop plane
28 is positioned to be a reference plane for the ends of the
optical fibers that extend from the first opening 18 through the
plurality of micro-holes 24 and across opening 30.
[0029] The front end 12 has a recessed portion 40 with a plurality
of lenses 42 visible therein. The plurality of lenses 42 are
preferably set back from the front face 44 of the front end 12 and
are precisely positioned to be in optical alignment with the
plurality of micro-holes 24 (and the optical fibers inserted
therein). Preferably, the number of lenses 42 corresponds to and
are in individual alignment with the number and position of the
micro-holes 24. The plurality of lenses 42 are molded with the rest
of the optical ferrule 10 and are generally a collimating-type
lens. That is, the lenses 42, because they are in contact with air
in the recessed portion 40, are collimating due to the difference
in the index of refraction between the polymer and the air and the
shape of the lens. The light exiting from the optical fibers
inserted into the optical ferrule 10 passes through the portion 46
of the optical ferrule 10 between the fiber stop plane 28 and the
lenses 42 and is then collimated into a near-parallel light beam to
be received by lenses of an identical, mated optical ferrule, which
then focus the received light onto the ends of the optical fibers
in that ferrule. It is anticipated that the front end 12 of the
optical ferrule 10 makes physical contact with the other optical
ferrule using the front faces 44. With the front faces 44 of two
opposing optical ferrules 10 making physical contact, the recessed
portion 40 of each of the optical ferrules 10 are sealed off from
the environment and prevents dust, oil, moisture, or other
contaminants from being deposited on the lenses and affecting the
properties of the lenses 42. Thus, the optical ferrule 10 is
designed for ferrule-to-ferrule contact rather than for
fiber-to-fiber contact as with MT ferrules.
[0030] The optical ferrule 10 may use loose optical fibers that are
inserted into the micro-holes 24 or, as illustrated in FIG. 7, the
optical fibers may be in the form of an optical ribbon 50.
Similarly, loose optical fibers may be bundled rather than be
ribbonized before being inserted into the optical ferrule 10.
[0031] Referring back to FIGS. 1-6, the optical ferrule 10 also has
guide pin openings 60 that extend from the front end 12 to the back
end 14. Guide pins as are known in the prior art may be used to
align the optical ferrules 10 with one another. It should be noted
that while the position and apparent size of the guide pin openings
60 are standard for the industry, the size, location, and/or pitch
of the guide pin openings 60 may be altered to prevent the optical
ferrule 10 from being mated to a standard ferrule, such as an MT
ferrule.
[0032] It is also possible, as is illustrated in FIG. 8 in an
alternative embodiment of unitary multi-fiber optical ferrule with
integrated lenses 10', that a molded guide pin 70 and a guide pin
opening 60' may be used rather than two guide pin openings. By
using one integrated, molded guide pin 70 and a guide pin opening
60', making it a hermaphroditic ferrule, only one hermaphroditic
ferrule type needs to be manufactured and still allow for mating
with the other hermaphroditic ferrules. By using a hermaphroditic
ferrule, fiber optic connectors using the optical ferrules 10' are
mated key-up to key-up instead of the typical key-up to key-down
configuration. By molding the guide pin 70, fewer parts are needed
in the assembly, since there is no need for the female pin clamp,
the male pin clamp, or the metal guide pins that are commonly used
in other optical ferrule formats.
[0033] Another alternative embodiment of an unitary multi-fiber
optical ferrule with integrated lenses 10'' is illustrated in FIG.
9. The optical ferrule 10'' preferably has an front end 12'', a
back end 14'', and a middle portion 16'' disposed between the front
end 12'' and the back end 14''. The optical ferrule 10'' also has a
first opening 18'' adjacent the back end 14'' to receive optical
fibers therein. The optical ferrule 10'' may also have an opening
20'' from the top surface 22'' of the optical ferrule 10'' that is
in communication with the first opening 18'' to inject epoxy to
secure optical fibers within the optical ferrule 10''. The front
end 12'' has a recessed portion 40'' with a plurality of lenses
42''. The optical ferrule 10'' has a plurality of micro-holes 24'',
the plurality of micro-holes 24'' being divided into a plurality of
rows, and a corresponding plurality of lenses 42'', the plurality
of lenses 42'' are divided into a plurality of rows. As noted
above, each of the micro-holes 24'' being aligned with a respective
lens 42''. The number of rows of micro-holes 24'' and lenses 42''
may be determined based on need and application. A fiber stop plane
28'' is disposed across an opening 30'' from the plurality of
micro-holes 24''. Preferably, the opening 30 opens to one of the
sides of the optical ferrule 10, which is the top side 22'' in this
embodiment of optical ferrule 10''. As illustrated in FIG. 9, three
rows of micro-holes 24'' and lenses 42'' are present for a 36 fiber
ferrule.
[0034] While the lenses 42 (and 42'') have been described as being
collimating lenses, they may also be focusing lenses so that the
optical ferrules (10, 10', and 10'') may be used with a different
form of optical ferrule, e.g., a standard MT ferrule. In this case,
the lenses 42 (and 42'') would focus the light to a point that
would correspond to the end of the optical fibers in the other
optical ferrules.
[0035] The process for inserting optical fibers, such as those in
the fiber optic ribbon 50, into the optical ferrules (10, 10', and
10'') is as follows. The optical fibers are stripped bare and
cleaned. The ends of the optical fibers are cleaved and then
inserted into the optical ferrule through the first opening 18 and
into the micro-holes 24. The optical fibers are pushed through the
micro-holes 24 until they reach the fiber stop plane 28 across the
opening 30. An index-matched epoxy is inserted into the openings 20
and 30 to secure the optical fibers in the optical ferrule. The
epoxy is light cured (UV and near-UV), which is usually less than
one minute in duration. Alternatively, a heat cured epoxy could be
used to secure the optical fibers in the ferrule. Then an optical
test is performed to ensure optical performance. This procedure
requires fewer steps and less equipment given that the ends of the
optical fibers do not extend through the end face of the optical
ferrule as in the MT ferrule discussed above. Additionally, there
is no polishing of the end face as noted above for the MT ferrule
and time can be reduced using a light-curable epoxy.
[0036] Another embodiment of a unitary multi-fiber optical ferrule
with integrated lenses 100 (optical ferrule) according to the
present invention is illustrated in FIGS. 10-13. The optical
ferrule 100 preferably has an front end 102, a back end 104, and a
middle portion 106 disposed between the front end 102 and the back
end 104. The optical ferrule 100 is a unitary ferrule, that is, a
single integral element that is preferably molded at the same time
from a homogeneous material. The optical ferrule 100 is an
optically clear polymer, which may include polyetherimide,
polycarbonate, cyclic olefin copolymer, cyclic olefin polymer, or
other transparent polymers. The optical ferrule 100 has a first
opening 108 adjacent the back end 104 to receive optical fibers
therein. The optical ferrule 100 may also have an opening 120 from
the top surface 122 of the optical ferrule 100 that is in
communication with the first opening 108 to inject epoxy to secure
optical fibers within the optical ferrule 100 as described in more
detail below. A plurality of micro-holes 124 extend through the
middle portion 106 to hold and position optical fibers inserted
into the first opening 108. The micro-holes 124 are preferably
tapered, being larger adjacent the first opening 108 than at the
opposite end. A fiber stop plane 128 is disposed across an opening
130 from the plurality of micro-holes 124. Preferably, the opening
130 opens to one of the sides of the optical ferrule 100, which is
the top surface 122 in this embodiment of optical ferrule 100.
Epoxy may also be injected into the opening 130 to further secure
the optical fibers in the optical ferrule 100. Preferably, the
epoxy used in the opening 130 and the first opening 108 is an
index-matched epoxy that is also preferably light curable. The
fiber stop plane 128 is positioned to be a reference plane for the
ends of the optical fibers that extend from the first opening 108
through the plurality of micro-holes 124 and across opening 130.
However, the optical fibers may be positioned in other ways as
well.
[0037] The front end 102 also has an integral guide pin 132 on one
side thereof and a guide pin opening 134 on the opposite side. As
will be recognized by one of ordinary skill in the art, the optical
ferrule 100 may have two integral guide pins 132 or two guide pin
openings 134. The front end 102 also has a recessed portion 140
with a plurality of lenses 142 visible therein. The plurality of
lenses 142 are preferably set back from the front face 144 of the
front end 102 and are precisely positioned to be in optical
alignment with the plurality of micro-holes 124 (and the optical
fibers inserted therein). Preferably, the number of lenses 142
corresponds to and are in individual alignment with the number and
position of the micro-holes 124. The plurality of lenses 142 are
molded with the rest of the optical ferrule 100. Moreover, the
lenses 142 have a forward most portion or apex that is preferably
between 50 and 200 microns from the front end 102. Most preferably,
the lenses 142 are only 50 microns from the front end 102 and the
front face 144 in particular. The optical ferrule 100 is cleaned
using a tool with a soft pile cloth to avoid scratching the lenses
142. If the lenses 142 are too deep, the tool may not be able to
reach the lenses 142 to clean them. If the lenses 142 are too close
to the front end 102, then they may get scratched. These distances
allow for the same tool to be used to clean several different sized
recessed portions 140.
[0038] The shape of the lenses 142 are different from the shape of
the lenses in the other embodiments. As noted above, the lenses 42
are shaped such that the light coming through the lens 42 is
generally collimated. This is illustrated in FIG. 14. However, if
the optical ferrule 10, 100 is not mated with another optical
ferrule, the light exiting the lens is small enough and
concentrated enough to damage a person's retina. The reason that
the light has typically been collimated is because the distances
between the opposite ferrules is not so important if the light is
collimated. In addition, for the case where the mated ferrules have
the same lens design, the optimum insertion loss is achieved with a
collimated beam. However, due the possibility of causing injury or
damage to a person's eye, something has to be done to reduce the
intensity of the light, which then has an effect on the distances
between the two lenses/ferrules. Shutters and other methods and
apparatus are known to block the light. However, in many instances,
these solutions are not optimal or practical. Therefore, if the
light exiting the lenses on the ferrule can be diverging, it is
possible to reduce the intensity. Thus, as illustrated in FIG. 15,
the lenses 142 are diverging lenses that have a divergence half
angle .THETA.. Preferably, the divergence half angle .THETA. is
between about 2 and 20 degrees. More preferably, the divergence
half angle .THETA. is not less than two degrees and most preferably
about 5 degrees. Taking this into account, if the ferrule (and its
connector) is in an adapter, the closest a person's eye could be to
the ferrule and lens is about 25 mm. If the light comes out of a
lens with a divergence half angle .THETA. of 5 degrees, then the
size of the light spot expands from 0.18 mm to more than 4.5 mm at
the 25 mm position. This greatly reduces the intensity of the light
and reduces the potential damage done to a person's eye.
[0039] FIG. 16 shows that the lens on a mated ferrule will
re-converge the light to focus it on the optical fiber. If the
divergence half angle .THETA. is larger than 5 degrees, then the
mated ferrule would have to have a different curvature to refocus
the light, or the losses would be extremely high.
[0040] FIG. 17 illustrates two optical ferrules 100 that are mated
to one another. The front ends 102 and particularly the front faces
144 of the optical ferrules 100 are in contact with one another.
This keeps dust and debris out of the recessed portion 140 and off
the lenses 142. With the lenses 50 microns from the front faces 144
of the optical ferrule 100, the distance between the lenses is only
100 microns and the divergence is not too great and cause a loss of
signal across the gap between the ferrules.
[0041] Another issue with the lenses 142 in the optical ferrules
100 is that it causes reflections of the light and increase loss.
One way to reduce the reflections and the attendant losses is to
apply an anti-reflective coating to the lenses. Anti-reflective
coatings are expensive and hard to apply, especially to such small
surfaces. They are also prone to scratching, particularly with the
cleaning necessary for the end faces. They also must pass
environmental testing without flaking and peeling. An alternative
is to mold protrusions 150 onto the exterior surface of the
plurality of lenses 142. See FIG. 18. If the protrusions are
smaller in all directions than the wavelength of the light passing
through them, then the protrusions 150 generally act like an
anti-reflective coating. It has been discovered that if the height
H and the width W of the protrusions 150 are smaller than 350 nm in
any one direction for use with the lenses 142, the lenses work
well. While the 350 nm dimensions are designed for white light, it
does work well with the 850 nm light used most often with the
optical ferrules. As the wavelengths of the light used can be 1310
or 1550 nm, the dimensions of the protrusions 150 may also get
larger.
[0042] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present invention
without departing from the spirit and scope of the invention. Thus
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *