U.S. patent application number 09/970974 was filed with the patent office on 2003-04-10 for integrated optical coupler and housing arrangement.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Brezina, Johnny Roy, Kerrigan, Brian Michael, Malagrino, Gerald Daniel JR., Moon, James Robert, Zumbrunnen, Michael Lynn.
Application Number | 20030068140 09/970974 |
Document ID | / |
Family ID | 25517774 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030068140 |
Kind Code |
A1 |
Brezina, Johnny Roy ; et
al. |
April 10, 2003 |
INTEGRATED OPTICAL COUPLER AND HOUSING ARRANGEMENT
Abstract
An optical coupler and housing arrangement includes a housing
portion adapted to receive an optical connector of a fiber optic
cable, and further includes an optical coupler portion integrally
formed with the housing portion. The optical coupler portion is
adapted to transmit optical signals to and from the fiber optic
cable. The optical coupler portion has a plurality of optical
fibers for transmitting the optical signals. Each of the optical
fibers extends from one end surface of the optical coupler portion
to another end surface of the optical coupler portion. The housing
portion has a recess for receiving the optical connector, with one
of the end surfaces of the optical coupler portion forming a back
surface of the recess.
Inventors: |
Brezina, Johnny Roy;
(Austin, TX) ; Kerrigan, Brian Michael; (Cary,
NC) ; Malagrino, Gerald Daniel JR.; (Rochester,
MN) ; Moon, James Robert; (Oronoco, MN) ;
Zumbrunnen, Michael Lynn; (Rochester, MN) |
Correspondence
Address: |
RABIN & BERDO, P.C.
SUITE 500
1101 14th STREET, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
ARMONK
NY
|
Family ID: |
25517774 |
Appl. No.: |
09/970974 |
Filed: |
October 5, 2001 |
Current U.S.
Class: |
385/92 ; 385/139;
385/76; 385/88 |
Current CPC
Class: |
G02B 6/4292 20130101;
G02B 6/421 20130101; G02B 6/4277 20130101 |
Class at
Publication: |
385/92 ; 385/76;
385/88; 385/139 |
International
Class: |
G02B 006/42; G02B
006/36 |
Claims
What is claimed is:
1. An optical coupler and housing arrangement, comprising: a
housing portion adapted to receive an optical connector of a fiber
optic cable; and an optical coupler portion integrally formed with
said housing portion, said optical coupler portion being adapted to
transmit optical signals to and from the fiber optic cable.
2. The optical coupler and housing arrangement recited in claim 1,
wherein said optical coupler portion has opposing end surfaces, and
a plurality of optical fibers for transmitting the optical signals,
each of said optical fibers extending from one of said end surfaces
to another one of said end surfaces.
3. The optical coupler and housing arrangement recited in claim 2,
wherein each of said optical fibers terminates in a region of the
respective end surfaces.
4. The optical coupler and housing arrangement recited in claim 3,
wherein each of said optical fibers has a length that is greater
than about 6 millimeters.
5. The optical coupler and housing arrangement recited in claim 2,
wherein said optical coupler portion further comprises a first pair
of alignment pins projecting from the one of said end surfaces and
being disposed to flank opposing sides of said optical fibers, and
a second pair of alignment pins projecting from the another one of
said end surfaces and being disposed to flank the opposing sides of
said optical fibers, said first pair of alignment pins being
engageable with the optical connector when received by said housing
portion, said second pair of alignment pins being engageable with a
die carrier.
6. The optical coupler and housing arrangement recited in claim 2,
wherein said housing portion has a recess for receiving the optical
connector, the one of said end surfaces forming a back surface of
the recess.
7. The optical coupler and housing arrangement recited in claim 6,
wherein said housing portion further includes integrally formed
latching fingers disposed on opposite sides of the recess and being
adapted to engage with the optical connector to secure the optical
connector within the recess.
8. The optical coupler and housing arrangement recited in claim 1,
wherein said housing portion and said optical coupler portion are
each comprised of a highly-filled polymer.
9. The optical coupler and housing arrangement recited in claim 1,
wherein said housing portion comprises a first housing portion, and
said optical coupler portion comprises a first optical coupler
portion; further comprising a second housing portion adapted to
receive a further optical connector; and a second optical coupler
portion integrally formed with said second housing portion; said
second housing portion being disposed adjacent to said first
housing portion and connected thereto.
10. The optical coupler and housing arrangement recited in claim 9,
wherein said second housing portion and said first housing portion
are integrally formed together.
11. An optical transceiver arrangement, comprising: an optical
coupler and housing arrangement, including a housing portion
adapted to receive an optical connector of a fiber optic cable; and
an optical coupler portion integrally formed with said housing
portion; and a carrier assembly having a carrier connected to said
housing portion, and a die chip connected to said carrier, said die
chip having at least one active region, said optical coupler
portion being adapted to transmit optical signals between the fiber
optic cable and the active region of said die chip.
12. The optical transceiver arrangement recited in claim 11,
further comprising: a laminate assembly having said carrier
disposed thereon, said die chip being electrically coupled to said
laminate assembly; and a cover disposed over said laminate assembly
and connected to said carrier.
13. The optical transceiver arrangement recited in claim 12,
wherein said cover is a heat sink for transferring heat from said
laminate assembly.
14. The optical transceiver arrangement recited in claim 12,
further comprising a flex cable electrically coupling said die chip
to said laminate assembly.
15. The optical transceiver arrangement recited in claim 14,
wherein said laminate assembly includes a wiring board having a
ground plane and at least one conductive pad disposed on a surface
of said wiring board, said conductive pad being electrically
coupled to said ground plane, said flex cable being electrically
coupled to said conductive pad.
16. The optical transceiver arrangement recited in claim 15,
wherein said laminate assembly includes a coating covering the
surface of said wiring board, said coating having at least one
recess formed therein that exposes said at least one conductive pad
to allow said flex cable to be electrically coupled to said
conductive pad.
17. The optical transceiver arrangement recited in claim 16,
wherein said flex cable has a conductive plate in electrical
contact with said at least one conductive pad, and having ground
wires electrically coupled to at least one of said die chip and
said carrier, said ground wires further being electrically coupled
to said conductive plate.
18. The optical transceiver arrangement recited in claim 17,
wherein said flex cable further has signal wires extending
therethrough, and an insulating coating covering said signal wires
and said ground wires, said insulating coating having at least one
window formed therein to expose said signal wires and said ground
wires, to allow said signal wires to be electrically coupled to
said die chip, and to allow the ground wires to be electrically
coupled to said at least one of said die chip and said carrier.
19. The optical transceiver arrangement recited in claim 14,
wherein said carrier has first and second spaced apart feet, said
flex cable extending between said spaced apart feet.
20. The optical transceiver arrangement recited in claim 12,
wherein said laminate assembly includes a wiring board having a
ground plane and at least one conductive pad disposed on a surface
of said wiring board, said conductive pad being electrically
coupled to said ground plane; and wherein said carrier has a foot
electrically coupled to said at least one conductive pad.
21. The optical transceiver arrangement recited in claim 12,
wherein said laminate assembly includes a wiring board and a
coating covering the surface of said wiring board, said coating
having a locating hole formed therein; and wherein said housing
portion has a locating pin extending from a bottom thereof, said
locating pin being received within the locating hole to position
said housing portion relative to said laminate assembly.
22. The optical transceiver arrangement recited in claim 11,
wherein said carrier has two spaced apart lands, said die chip
being disposed between said lands, said optical coupler portion
being fixed to said lands so as to be positioned in front of said
active region.
23. The optical transceiver arrangement recited in claim 22,
wherein each land has an alignment hole formed therein; and wherein
said optical coupler portion further has opposing end surfaces and
a first pair of alignment pins projecting from one of the end
surfaces, and a second pair of alignment pins projecting from
another one of the end surfaces, said first pair of alignment pins
being engageable with the optical connector when received by said
housing portion, said second pair of alignment pins being
receivable by respective alignment holes of said carrier.
24. The optical transceiver arrangement recited in claim 11,
further comprising an electromagnetic interference shield disposed
around said housing portion.
25. The optical transceiver arrangement recited in claim 11,
wherein said optical coupler portion has opposing end surfaces, and
a plurality of optical fibers for transmitting the optical signals,
each of said optical fibers extending from one of said end surfaces
to another one of said end surfaces.
26. The optical transceiver arrangement recited in claim 25,
wherein each of said optical fibers terminates in a region of the
respective end surfaces.
27. The optical transceiver arrangement recited in claim 26,
wherein each of said optical fibers has a length that is greater
than about 6 millimeters.
28. The optical transceiver arrangement recited in claim 25,
wherein said housing portion has a recess for receiving the optical
connector, the one of said end surfaces forming a back surface of
the recess.
29. The optical transceiver arrangement recited in claim 28,
wherein said housing portion further includes integrally formed
latching fingers disposed on opposite sides of the recess and being
adapted to engage with the optical connector to secure the optical
connector within the recess.
30. The optical transceiver arrangement recited in claim 11,
wherein said housing portion and said optical coupler portion are
each comprised of a highly-filled polymer.
31. The optical transceiver arrangement recited in claim 12,
wherein said housing portion comprises a first housing portion, and
said optical coupler portion comprises a first optical coupler
portion; further comprising a second housing portion adapted to
receive a further optical connector; and a second optical coupler
portion integrally formed with said second housing portion; said
second housing portion being disposed adjacent to said first
housing portion and connected thereto; further comprising an
electromagnetic interference shield disposed around said first
housing portion and said second housing portion to retain said
housing portions in a side-by-side relationship.
32. The optical transceiver arrangement recited in claim 31,
wherein said laminate assembly includes a wiring board having a
ground plane and at least one conductive pad disposed on a surface
of said wiring board, said conductive pad being electrically
coupled to said ground plane; wherein said cover is a heat sink for
transferring heat from said laminate assembly; and wherein said
cover has a downwardly-projecting finger that extends between said
housing portions and engages with said conductive pad to provide
for electromagnetic separation.
33. A computer, comprising: a frame; a circuit board disposed
within said frame; and an optical transceiver arrangement,
comprising: an optical coupler and housing arrangement, including a
housing portion adapted to receive an optical connector of a fiber
optic cable; and an optical coupler portion integrally formed with
said housing portion; and a carrier assembly having a carrier
connected to said housing portion, and a die chip connected to said
carrier, said die chip having at least one active region, said
optical coupler portion being adapted to transmit optical signals
between the fiber optic cable and the active region of said die
chip.
34. The computer recited in claim 33, wherein said optical
transceiver arrangement further comprises: a laminate assembly
having said carrier disposed thereon, said die chip being
electrically coupled to said laminate assembly; and a cover
disposed over said laminate assembly and connected to said
carrier.
35. The computer recited in claim 33, wherein said cover is a heat
sink for transferring heat from said laminate assembly.
36. The computer recited in claim 34, wherein said optical
transceiver arrangement further comprises a flex cable electrically
coupling said die chip to said laminate assembly.
37. The computer recited in claim 33, wherein said housing portion
comprises a first housing portion, and said optical coupler portion
comprises a first optical coupler portion; wherein said optical
coupler and housing arrangement further comprises a second housing
portion adapted to receive a further optical connector; and a
second optical coupler portion integrally formed with said second
housing portion; said second housing portion being disposed
adjacent to said first housing portion and connected thereto.
38. The computer recited in claim 37, wherein said optical
transceiver arrangement further comprises an electromagnetic
interference shield disposed around said first housing portion and
said second housing portion to retain said housing portions in a
side-by-side relationship.
39. The computer recited in claim 33, further comprising a
tailstock attached to said frame; wherein said optical transceiver
arrangement further includes an electromagnetic interference shield
disposed about said housing portion, and being engageable with said
tailstock.
40. The computer recited in claim 34, wherein said cover of said
optical transceiver arrangement defines a heat sink disposed over
said laminate assembly.
41. The computer recited in claim 40, wherein said housing portion
has a rearwardly projecting ear in contact with said heat sink and
establishing a gap between said carrier and said heat sink.
42. A method of making an optical coupler and housing arrangement,
comprising: integrally forming together a housing portion and an
optical coupler portion, said integrally forming including:
adapting the housing portion to receive an optical connector of a
fiber optic cable; and adapting the optical coupler portion to
transmit optical signals to and from the fiber optic cable.
43. The method recited in claim 42, wherein said integrally forming
includes molding the housing portion and the optical coupler
portion.
44. The method recited in claim 43, wherein the housing portion and
the optical coupler portion are simultaneously molded in a same
operation.
45. The method recited in claim 44, wherein the housing portion and
the optical coupler portion are simultaneously injection molded in
the same operation.
46. The method recited in claim 42, wherein said integrally forming
includes: arranging a plurality of optical fibers in a
predetermined configuration; and after said arranging, performing a
molding operation to simultaneously form said housing portion and
said optical coupler portion while maintaining the predetermined
configuration.
47. The method recited in claim 46, wherein said arranging includes
aligning end faces of the optical fibers.
48. The method recited in claim 46, wherein said performing
includes performing an injection molding operation.
49. The method recited in claim 46, wherein said performing forms
the optical coupler to have opposing end surfaces, with each of the
optical fibers extending from one of the end surfaces to another
one of the end surfaces.
50. The method recited in claim 46, wherein said performing
includes molding the housing portion to have a recess for receiving
the optical connector of the fiber optic cable, and to have
integrally formed latching fingers disposed on opposite sides of
the recess, the latching fingers being adapted to engage with the
optical connector to secure the optical connector within the
recess.
51. The method recited in claim 46, wherein performing includes
performing an injection molding operation that additionally fixes
the optical fibers in place.
52. The method recited in claim 42, wherein the housing portion and
the optical coupler portion are each comprised of a highly-filled
polymer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The subject matter of this application is related to the
disclosures contained within U.S. patent application Ser. No.
09/894,934, attorney docket no. ROC920010154US1-IBM-212, entitled
Enhanced Optical Transceiver Arrangement; within U.S. patent
application Ser. No. 09/894,714, attorney docket no.
ROC920010151US1-IBM-210, entitled Enhanced Optical Coupler; and
within U.S. patent application Ser. No. 09/xxx,xxx, attorney docket
no. ROC92001118US1, entitled A Processing Protective Plug Insert
for Optical Modules, all having been assigned to International
Business Machines, Corporation, and all having been filed on Jun.
28, 2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an integrated optical
coupler and housing arrangement, and in particular, to a housing
and integrated optical coupler arrangement that is used to
optically couple and align a light emitter or light detector with
an optical fiber connector.
[0004] 2. Background Information
[0005] Computer and communication systems are now being developed
in which optical devices, such as optical fibers, are used as a
conduit (also known as a wave guide) for modulated light waves to
transmit information. These systems typically include a light
emitter or a light detector optically connected to the optical
fibers. A typical light emitter may be a so-called edge emitter, or
a surface emitter, such as a vertical cavity surface emitting laser
(VCSEL). A typical light detector may be a photodiode. A generic
term of either a light emitter or a light detector is an
"optoelectronic transducer." The optical fibers, which collectively
form a fiber-optic cable or ribbon, are typically coupled to the
respective light detector and the light emitter, so that optical
signals can be transmitted back and forth, for example.
[0006] As an example, optoelectronic transducers convert electrical
signals to or from the optical signals; the optical signals carry
data to a receiver (light detector) from a transmitter (light
emitter) via the fiber-optic ribbon at very high speeds. Typically,
the optical signals are converted into, or converted from, the
associated electrical signals using known circuitry. Such
optoelectronic transducers are often used in devices, such as
computers, in which data must be transmitted at high rates of
speed.
[0007] The conventional light emitter allows for integrated
two-dimensional array configurations. For example, the active
regions (i.e., the region that transmits or receives the optical
signals) of a conventional VCSEL can be arranged in a linear array,
for instance 12 active regions spaced about 250 microns apart, or
in area arrays, for example, 16.times.16 arrays or 8.times.8
arrays. Of course, other arrangements of the arrays are also
possible. Nevertheless, linear arrays are typically considered to
be preferable for use with optoelectronic transducers, since it is
generally considered easier to align the optical fibers that
collect the light emitted from the VCSELs in a linear array, than
in an area array. Moreover, it is also possible to utilize the
active regions singly, i.e., without being arranged in an
array.
[0008] The optoelectronic transducers are normally located on
either input/output cards or port cards that are connected to an
input/output card. Moreover, in a computer system, for example, the
input/output card (with the optoelectronic transducer attached
thereto) is typically connected to a circuit board, for example a
mother board. The assembly may then be positioned within a chassis,
which is a frame fixed within a computer housing. The chassis
serves to hold the assembly within the computer housing.
[0009] Typically, each optical fiber of the fiber-optic ribbon is
associated with a respective active region. Further, it is
conventional for the ends of the optical fibers of the fiber-optic
ribbon to terminate in a fiber connector. Such fiber connectors
usually have an industry standard configuration, such as the
MTP.RTM. fiber connectors manufactured by US Conec, Ltd. of
Hickory, N.C. However, fiber connectors having the industry
standard configuration are not suitable for connecting directly
with the sensitive active regions of the typical light emitters or
light detectors. Should direct contact occur between the respective
active regions and the fiber connector, the fiber connector would
likely damage the active regions, causing the light emitter or
light detector to become inoperative. It is thus conventional to
space the fiber connector away from the active regions. However, as
will be appreciated, by providing a space, it thus becomes
desirable to provide a way of optically coupling the active regions
with the spaced apart fiber connector, so that the optical signals
can be accurately and efficiently transmitted therebetween.
[0010] One conventional manner of optically coupling the active
regions with the fiber connector is to provide a lens assembly in
the space therebetween. However, lens assemblies tend to be
complicated and expensive. Thus, it is also known to provide a
fiber optic coupler between the active regions and the fiber
connector. However, the conventional fiber optic coupler has a
limited length, due to manufacturing constraints. Thus, the known
fiber connectors must be positioned relatively close to the active
regions, which may limit design options.
[0011] Moreover, it is important to ensure that most of the light
emitted from the active regions of the light emitter reaches the
respective optical fibers, and that most of the light emitted from
the optical fibers reaches the respective active regions of the
light detector. It is thus desirable to ensure that the fiber optic
coupler is precisely aligned with the respective active regions and
the fiber ends disposed within the fiber connector.
[0012] It is also known to dispose the optical coupler within a
housing, which is adapted to receive the optical connector in a
manner that automatically aligns the optical fibers terminating at
the optical connector with the optical coupler. The housing also
allows the optical coupler to be fixed relative to the light
emitter and/or light detector. That is, after the optical coupler
is aligned with the respective active regions, the optical coupler
may be fixed to the housing using a bonding agent, for example.
However, the application of the bonding agent requires further
steps during the manufacturing of the arrangement, thus increasing
assembly time. Moreover, the bonding agent could inadvertently be
applied to the optical face of the optical coupler, or to the
active regions, thus damaging the assembly.
[0013] Thus, there is a need for an optical coupler/housing
arrangement that allows the optical coupler to be fixed relative to
the housing without requiring an extra bonding step, or a separate
bonding agent.
[0014] Furthermore, the conventional optical coupler is typically
freely positionable within the housing, prior to the application of
the conventional bonding agent. For example, the housing may be
provided with a channel, with the optical coupler being disposed in
the channel. In order to ensure that the optical coupler can be
positioned within the housing, the outer periphery of the optical
coupler is made slightly smaller than an inner periphery of the
channel, so that the optical coupler fits within the channel with a
clearance fit. However, it must also be ensured that when the
optical connector is connected to the housing, the optical coupler
is aligned with the optical fibers that terminate at the optical
connector. Thus, both the channel within the housing, and the
optical coupler must be manufactured using relatively strict
tolerances. That is, if the optical coupler is made as large as the
tolerances allow, and the channel is made as narrow as the
tolerances allow, the optical coupler must still be capable of
fitting within the channel with a clearance fit. Moreover, once
received within the channel, there cannot be too much free play, or
the optical coupler may not be properly aligned with the optical
fibers terminating at the optical connector. Manufacturing these
components while maintaining the required tolerances is expensive
and time consuming. Thus, there is a need for an optical coupler
and housing arrangement that can be manufactured without regard to
the tolerances discussed above.
SUMMARY OF THE INVENTION
[0015] It is, therefore, a principle object of this invention to
provide an integrated optical coupler and housing arrangement.
[0016] It is another object of the invention to provide an
integrated optical coupler and housing arrangement that solves the
above mentioned problems.
[0017] These and other objects of the present invention are
accomplished by the integrated optical coupler and housing
arrangement disclosed herein.
[0018] According to one aspect of the invention, the integrated
optical coupler and housing arrangement includes an optical coupler
portion. The optical coupler portion optically couples active
regions of a light emitter die chip or light detector die chip with
the fibers within a fiber optic connector (i.e., an industry
standard connector attched to an end of an optical fiber ribbon),
so that the optical signals can be accurately and efficiently
transmitted therebetween.
[0019] The integrated optical coupler and housing arrangement
further includes a housing portion that has a recess for receiving
the fiber optic connector, and which is adapted to selectively
receive either the MPO or MTP industry standard connector, for
example. A back surface of the recess is defined by an end surface
of the optical coupler portion. Thus, when the fiber optic
connector is received within the recess, the optical fibers of the
optical coupler portion will be positioned adjacent to the fiber
optic connector.
[0020] The housing portion may also be provided with a pair of
latching fingers disposed on opposite sides of the recess. The
latching fingers are adapted to engage with the fiber optic
connector, to hold the connector in place.
[0021] In an exemplary aspect of the invention, the housing portion
and the optical coupler portion are formed from a filled polymer,
i.e., a polymer that includes a glass filler. In an exemplary
aspect of the invention, the polymer has a glass content of about
30%. This content has proven to be particularly suitable when
manufacturing the housing portion and the optical coupler portion
using the molding techniques discussed in the following
paragraphs.
[0022] In particular, in an exemplary aspect of the invention, the
housing portion and the optical coupler portion are manufactured
using an injection molding technique. The optical coupler portion,
if injection molded, can be made to have any desired length. That
is, the optical fibers, of any desired length, may be prearranged
in their desired locations, and then the filled polymer would be
injected around the fibers to form the optical coupler portion.
This exemplary procedure is farther advantageous in that, since the
optical fibers do not need to be inserted within holes preformed in
the optical coupler, the optical fibers will not be subjected to
damage during such a procedure. Moreover, because the injection
molding procedure also inherently fixes the optical fibers in their
desired locations, there is no need for a separate bonding
procedure to fix the optical fibers in place. Additionally, since a
separate bonding agent is not needed to fix the optical fibers
within the optical coupler portion, there is a reduced risk of the
optical fibers being damaged due to the boding agent inadvertently
contacting the optical fibers or other components.
[0023] This exemplary aspect of the invention also eliminates the
need for a subsequent polishing step to the end faces of the
optical fibers. That is, if the optical fibers are inserted within
the holes of an optical coupler, the end faces would subsequently
need to be polished, so as to remove any scratches or contaminates
that may have formed on the end faces during the insertion
procedure, and to ensure that all of the end faces are disposed in
essentially the same plane and at essentially the same relative
angle. However, when the optical fiber portion is formed by
injection molding, the end faces of the optical fibers are not
subjected to treatment after assembly that may cause damage
thereto. Moreover, the end faces can be prealigned, so that even
after the formation of the optical fiber portion, the end faces are
in their desired aligned orientation.
[0024] The exemplary described technique used for forming the
optical coupler portion can also be used to simultaneously form the
housing portion, so that the optical coupler portion and the
housing portion are integrally formed. This reduces the number of
separate components that must otherwise be formed. Further, this
technique eliminates the need to manufacture the mating surfaces of
the housing and optical coupler using exacting tolerances, thus
speeding up production. Additionally, this procedure eliminates the
need to separately adhere the optical coupler to the housing, thus
reducing the number of manufacturing steps, and reducing the risk
of contamination to the components from bonding agents.
[0025] In another exemplary aspect of the invention, the housing
portion and fingers are molded to have a one-piece configuration.
This reduces assembly time by eliminating the need to fix separate
latching fingers to the housing, and reduces inventory by
eliminating multiple parts.
[0026] In another exemplary aspect of the invention, the integrated
optical coupler and housing arrangement can include first and
second housing portions disposed side-by-side, each of which has an
optical coupler portion integrally formed therewith. This
configuration allows both a light emitter and a light detector, for
example, to be disposed in the same assembly, therefore saving
circuit board space. The respective housings can be manufactured
separately and joined together, for example, or the two housings
can be integrally molded together.
[0027] In another exemplarily aspect of the invention, the front
end of the integrated optical coupler and housing arrangement may
also be provided with an electromagnetic interference shield. The
electromagnetic interference shield is preferably formed from a
conductive, non-corrosive material, such as steel having a tin
plating. However, the electromagnetic interference shield can be
formed of any material that will attenuate electromagnetic
interference.
[0028] The electromagnetic interference shield may be hollow, to
allow the shield to be slipped over the front end of the integrated
optical coupler and housing arrangement. When properly positioned,
the edge of the electromagnetic interference shield will be
positioned essentially flush with the front end of the housing
portion. The shield may be provided with inwardly projecting
fingers that engage with the surface of the housing portion, to
hold the shield in place.
[0029] In another exemplary aspect of the invention, the
electromagnetic interference shield is provided with a number of
conductive grounding springs, which are disposed around the outer
periphery of an end of the shield. The grounding springs engage,
for example, with a tailstock attached to a system frame of a
computer, for example, to conductively couple the electromagnetic
interference shield to a ground potential. When properly
positioned, the grounding springs hold the electromagnetic
interference shield in a fixed position relative to the
tailstock.
[0030] The shield can advantageously be used to hold the first and
second housing portions together, when two separate housing
portions are provided. That is, the shield can be slid around the
adjacent housing portions, and serve as a clamp to retain the
housing portions in their relative positions.
[0031] In an exemplary aspect of the invention, the integrated
optical coupler and housing arrangement forms a component of an
optical transceiver arrangement that includes a plurality of other
interconnected subassemblies.
[0032] One of the subassemblies of the optical transceiver
arrangement is a carrier assembly. The carrier assembly includes a
die carrier for carrying a die chip, having opposing lands. The
opposing lands have a receiving space therebetween, in which either
a light emitter die chip or light detector die chip (hereinafter
referred to collectively as a die chip) is disposed.
[0033] The carrier is preferably manufactured from a conductive
material, so that it can serve as a ground for the die chip. For
example, the carrier can be formed from copper, and be gold plated
to enhance its conductivity and reduce its susceptibility to
oxidation.
[0034] The carrier further has spaced apart feet, which can be
attached to a further subassembly of the optical transceiver
arrangement, as will be subsequently described. The feet provide a
space under the carrier in which other components can be
disposed.
[0035] The lands are adapted to allow an optical coupler to be
attached thereto. For example, each land can be provided with a
receiving hole, which receives a corresponding alignment pin of the
optical coupler in a clearance type fit.
[0036] In another exemplary aspect of the invention, an epoxy, for
example, can be used to seal the exterior edges of the optical
coupler portion to the surface of the die chip. The epoxy may have
a sufficiently high viscosity so as to prevent the epoxy from
flowing into the gap between the front edge of the optical coupler
portion and the active regions of the die chip. Thus, a sealed air
gap will be formed between the ends of the optical fibers in the
optical coupler portion and the active regions to allow for the
efficient transmission of light, while preventing contaminants from
entering this space.
[0037] In a further exemplary aspect of the invention, the carrier
assembly includes a flex cable that is electrically coupled to the
die chip. The flex cable has both ground wires (or a ground layer)
and signal wires which may be covered by an insulating coating,
such as plastic. The insulating coating may be removed in a region
at one end of the flex cable, to form one or more windows which
expose the signal wires, grounds wires or both as they pass through
the space of the windows. For example, if the flex cable is
provided with two windows, one disposed over the other, the lower
window can be adapted to expose the ground wires, to allow the
ground wires to be electrically coupled to the conductive carrier.
The upper window can then be adapted to expose the signal wires,
which can then be electrically coupled to the die chip. This
arrangement works well when the die chip is attached and directly
grounded to the carrier. Alternatively, if the die chip is not
directly grounded to the carrier, then the flex cable can be
provided with only one window, which is adapted to expose both the
ground wires and the signal wires. These can then be electrically
coupled to the die chip, for example a light detector die chip, to
provide both a signal path and a return ground path.
[0038] Another end of the flex cable may be provided with a
conductive plate, such as a metal stiffener, electrically bonded to
the ground wires/ground layer of the flex cable. This conductive
plate can then be attached to a ground potential, in a manner that
will be subsequently described.
[0039] In use, the flex cable may be arranged to extend down the
front of the carrier (i.e., on the side the die chip is disposed),
and then flexed and bent to pass between the feet of the carrier
and through the space therebetween. Thus, the conductive plate will
then be disposed in a region behind the carrier.
[0040] In a further exemplary aspect of the invention, the optical
transceiver arrangement further includes a laminate assembly. The
laminate assembly includes a printed circuit board or wiring board,
that has a plurality of superposed, alternating conductive layers
and insulating layers formed in discrete planes. A front surface of
the wiring board may have various electronic components, such as a
light emitter driver chip and/or light detector driver chip,
attached thereto, and may have electrically conductive pathways or
wirings (also known as traces) between the components. The driver
chips may be positioned so that in the final optical transceiver
arrangement, the driver chips are positioned away from the carrier
to aid in heat dissipation.
[0041] The wiring board can be adapted to allow it to be attached
to a further printed circuit board, for example, by an end user. By
way of example, the lower surface of the wiring board can be
provided with a plurality of conductive pads arranged in an array,
each of which is coupled to a ground plane, power plane and wiring
plane of the board, using vias, for example, and each of which may
be attached to a respective lead of the further printed circuit
board using ball grid array (BGA) technology.
[0042] The laminate assembly may further include a polymer coating
disposed on the upper surface of the wiring board, and upon which
the housing portion can be disposed. The polymer coating may be
relatively thick, and formed to provide locating features to
facilitate the positioning of the various other subassemblies. For
example, the housing portion may be provided with one or more
projecting pins on a lower surface thereof, and the polymer coating
may be provided with receiving holes that accommodate the
respective projecting pins. Thus, during manufacturing, the housing
portion can be quickly located on the laminate assembly in the
desired location. Moreover, the coating protects the wirings and
components on the surface of the wiring board, and helps to
distribute heat generated by the drivers over a larger surface
area.
[0043] Moreover, the polymer coating may be provided with one or
more recesses formed therein, to expose respective conductive pads
that are electrically coupled to the ground plane. The feet of the
carrier can then be electrically bonded, using an electrical epoxy
for example, to the conductive pads so that the carrier is
electrically coupled to the ground plane. Moreover, the conductive
plate of the flex cable may be electrically bonded to another
conductive pad, to provide another means of electrically coupling
the ground plane to the die chip and carrier. Further, the signal
wires of the flex cable may be coupled, for example wire bonded, to
respective signal traces on the surface of the laminate.
Thereafter, the various electrical connections can be coated to
protect the connections and wires from being damaged. For example,
the coating can be a so-called chip coat epoxy material.
[0044] During the coupling of the flex cable to the laminate
assembly, the housing portion may also be fixed to the laminate
assembly. For example, the housing portion may be epoxied to the
laminate assembly.
[0045] In another exemplary aspect of the invention, the optical
transceiver arrangement may include a heat sink cover disposed over
the laminate assembly. In this exemplary aspect of the invention,
the polymer coating may include a step arranged around an outer
periphery thereof, and the heat sink cover may have a flange that
engages with the step to position the heat sink cover relative to
the laminate assembly. Once in position, the heat sink cover can
transfer and dissipate heat generated by the drivers, for
example.
[0046] The heat sink cover may also be provided with a
downwardly-projecting finger that is adapted to engage with an
exposed conductive pad of the wiring board, which is coupled with
the ground plane. In this manner, when the heat sink cover is in
position, the heat sink cover will be electrically coupled with a
ground potential, allowing the heat sink cover to serve as a
further ground potential for the light emitter/light detector.
Moreover, the downwardly-projecting finger can be positioned to
extend between adjacent housing portions (when so provided), and in
particular between the respective light emitter and light detector
when so provided, to serve as an electromagnetic emissions
separator. Thus, the heat sink cover can help prevent
electromagnetic interference from occurring between the light
emitter and light detector.
[0047] When properly positioned, the heat sink cover may be bonded
in place, for example using an epoxy, and may be positioned to abut
against a back of the retainer assembly.
[0048] The present invention results in an optical transceiver
arrangement in which various delicate components are sealed and
protected. Moreover, the thermal characteristics are optimized,
resulting in increased efficiency. Further, optical clarity is
enhanced and the resulting structure can be easily assembled and
used in small spaces. Further, the arrangement allows for both a
transmitter and detector in the same package. Additionally, this
arrangement allows MPO and MTP optical connectors to be selectively
attached thereto. Further, the resulting optical transceiver
arrangement has fewer parts, thus reducing inventory and reducing
manufacturing time. Moreover, due to the elimination of a separate
optical coupler, the reliability of the resulting structure is
enhanced, since the optical coupler portion cannot shift or become
separated from the housing portion, or become damaged during
assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 is a rear perspective view of an integrated optical
coupler and housing arrangement, according to an exemplary aspect
of the invention.
[0050] FIGS. 2 and 3 are sectional views of the integrated optical
coupler and housing arrangement shown in FIG. 1.
[0051] FIG. 4 is a partial sectional view of an optical transceiver
arrangement, according to an exemplary aspect of the invention,
taken along section lines 4-4 in FIG. 6.
[0052] FIG. 5 is an enlarged view of a portion of the sectional
view shown in FIG. 4.
[0053] FIG. 6 is a front elevational view of the optical
transceiver arrangement.
[0054] FIG. 7 is a perspective front view of the integrated optical
coupler and housing arrangement, according to an exemplary aspect
of the invention.
[0055] FIG. 8 is a perspective view of a portion of the optical
transceiver arrangement shown in FIG. 4.
[0056] FIG. 9 is a perspective view of an EMI shield of the optical
transceiver arrangement.
[0057] FIG. 10 is a perspective view of the optical transceiver
arrangement having the shield shown in FIG. 9 attached thereto,
according to an exemplary aspect of the invention.
[0058] FIG. 11 is a perspective view of the optical transceiver
arrangement shown in FIG. 10, disposed within a computer.
[0059] FIG. 12 is an elevational view of a carrier subassembly of
the optical transceiver arrangement.
[0060] FIG. 13 is a perspective view of the carrier subassembly of
the optical transceiver arrangement.
[0061] FIGS. 14 and 15 are various views of a laminate subassembly
of the optical transceiver arrangement shown in FIG. 10.
[0062] FIGS. 16 and 17 are various views of the wiring board of the
laminate subassembly shown in FIGS. 14 and 15.
[0063] FIG. 18 is a bottom view of the housing portion of the
integrated optical coupler and housing arrangement.
[0064] FIG. 19 is a perspective view of a heat sink cover of the
optical transceiver arrangement shown in FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] The invention will now be described in more detail by way of
example with reference to the embodiments shown in the accompanying
figures. It should be kept in mind that the following described
embodiments are only presented by way of example and should not be
construed as limiting the inventive concept to any particular
physical configuration.
[0066] Further, in the application, the terms "upper", "lower",
"front", "back", "over", "under", and similar such terms are not to
be construed as limiting the invention to a particular orientation.
Instead, these terms are used only on a relative basis.
[0067] Referring to FIGS. 1-3, the present invention is directed
toward an integrated optical coupler and housing arrangement 2,
which includes an optical coupler portion 4. The optical coupler
portion 4 optically couples active regions of a light emitter die
chip 6 or light detector die chip 6 (see FIGS. 4 and 5, and
hereinafter referred to collectively as a die chip 6) with the
fibers of a spaced apart fiber optic connector (not shown), such as
an industry standard MPO/MTP connector, so that the optical signals
can be accurately and efficiently transmitted therebetween.
[0068] The optical coupler portion 4 has two opposing end surfaces
7, 7', one of which faces toward the active regions, and the other
of which faces toward the fiber optic connector. The optical
coupler portion 4 further includes a plurality of spaced apart
optical fibers 8, each of which extends from the one end surface 7
to the other end surface 7'. The optical fibers 8 are used to
transmit optical signals between the fiber optic connector and the
active regions. The optical fibers terminate in a region of the
respective end surfaces; however, they may extend slightly beyond
the end surfaces.
[0069] The integrated optical coupler and housing arrangement 2
further includes a housing portion 10 that has a recess 12 for
receiving the fiber optic connector, and which is adapted to
selectively receive either the MPO or MTP connector, for example. A
back surface of the recess 12 is defined by the end surface 7' of
the optical coupler portion 4. Thus, when the fiber optic connector
is received within the recess 12, the optical fibers 8 of the
optical coupler portion 4 will be positioned adjacent to the fiber
optic connector.
[0070] As best shown in FIGS. 6 and 7, the housing portion 10 may
also be provided with a pair of latching fingers 14 disposed on
opposite sides of the recess 12. The latching fingers 14 are
adapted to engage with the fiber optic connector, to hold the
connector in place.
[0071] Moreover, and as shown in FIG. 8, when not attached to the
fiber optic connector, a plug 15 can be inserted in the recess 12
and retained therein by the latching fingers 14. The plug 15
prevents contaminants from entering the integrated optical coupler
and housing arrangement 2, when the arrangement is not in use.
[0072] In an exemplary aspect of the invention, the housing portion
10 and the optical coupler portion 4 are formed from a filled
polymer, i.e., a polymer that includes a glass filler. In an
exemplary aspect of the invention, the polymer has a glass content
of about 30%. This content has proven to be particularly
advantageous when manufacturing the housing portion 10 and the
optical coupler portion 4 using the molding techniques discussed in
the following paragraphs.
[0073] In particular, in an exemplary aspect of the invention, the
housing portion 10 and the optical coupler portion 4 are
manufactured using an injection molding technique. The specifics of
injection molding are well known to those skilled in the art, from
other fields of endeavor, and will not be discussed in detail.
However, the use of other manufacturing techniques, such as
transform molding, may limit the maximum size of the optical
coupler to about 6 millimeters in length. One reason for this
limitation is that when an optical coupler is manufactured using
transform molding techniques, small through holes for receiving the
optical fibers must be molded into the optical coupler. After the
optical coupler and holes are formed, the optical fibers are
individually inserted into the holes, and adhered into place.
However, current technology only allows holes of such a small
diameter to be accurately formed to a maximum length of about 6 mm.
This relatively short length limits the design options when using
such an optical coupler. Moreover, the insertion of the optical
fibers into the holes can cause the end faces of the optical fibers
to become damaged, thus requiring that the end faces of the optical
fibers be subjected to a subsequent polishing step. Further, the
adhering of the optical fibers into the respective holes requires
yet a further operation to perform this task, and increases the
risk that the optical fibers (or other components) will become
contaminated by the bonding agent On the other hand, the optical
coupler portion 4 according to the present invention, if injection
molded, can be made to have any desired length. That is, when
injection molded, the optical fibers 8 are first prearranged in
their desired locations, and then the filled polymer is injected
around the fibers to form the optical coupler portion 4. Thus,
whereas the conventional manufacturing techniques limited the size
of the optical coupler by the length of the hole, injection molding
allows the optical coupler portion to have any desired length,
including lengths greater than 6 millimeters, since individual
holes for the optical fibers need not be formed.
[0074] This procedure is further advantageous in that, since the
optical fibers 8 do not need to be inserted within holes preformed
in the optical coupler, the optical fibers will not be subjected to
damage during such a procedure. Moreover, because the injection
molding procedure also inherently fixes the optical fibers 8 in
their desired locations, there is no need for a separate bonding
procedure to fix the optical fibers in place. Additionally, since a
separate bonding agent is not needed to fix the optical fibers
within the optical coupler portion 4, there is a reduced risk of
the optical fibers being damaged due to the bonding agent
inadvertently contacting the optical fibers or other
components.
[0075] This exemplary aspect of the invention also eliminates the
need for a subsequent polishing step to the end faces of the
optical fibers. That is, if the optical fibers are inserted within
the holes of an optical coupler, the end faces will subsequently
require polishing, so as to remove any scratches or contaminates
that may have formed on the end faces during the insertion
procedure, and to ensure that all of the end faces are disposed in
essentially the same plane and at essentially the same relative
angle. However, when the optical fiber portion is formed by
injection molding, the end faces of the optical fibers are not
subjected to treatment that may cause damage thereto. Moreover, the
end faces can be prealigned, so that immediately after the
formation of the optical fiber portion, the end faces are in their
desired aligned orientation.
[0076] Prior to the present invention, it was not believed to be
advantageous to form a housing and an optical coupler in an
integral arrangement. That is, it was conventionally believed that
the end faces of the fibers of the optical coupler required
polishing after their insertion within the holes. However, this
polishing could only be economically performed if the optical
coupler were separate from the housing.
[0077] However, the exemplary described technique used for forming
the optical coupler portion 4 can also be used to simultaneously
form the housing portion 10, so that the optical coupler portion
and the housing portion are integrally formed. In the context of
the present application, "integrally formed" is meant that there is
no set or defined boundary (i.e., transition) between the optical
coupler portion and the housing portion, as there would be if an
optical coupler were adhered within a housing. Instead, the optical
coupler portion is formed with the housing portion, so that these
two features are inseparable, and incapable at any time of existing
on their own.
[0078] This aspect of the invention reduces the number of separate
components that must otherwise be formed. Further, this technique
eliminates the need to manufacture the mating surfaces of the
housing and optical coupler using exacting tolerances, thus
speeding up production. Additionally, this procedure eliminates the
need to separately adhere the optical coupler to the housing, thus
reducing the number of manufacturing steps, and reducing the risk
of contamination to the components from bonding agents. Moreover,
this aspect of the invention ensures that the optical coupler
cannot inadvertently become separated from, or shift relative to
the housing portion.
[0079] In another exemplary aspect of the invention, the housing
portion 10 and latching fingers 14 are preferably molded to have a
one-piece configuration (i.e., integrally formed). This reduces
assembly time by eliminating the need to fix separate latching
fingers 14 to the housing, and reduces inventory by eliminating
multiple parts.
[0080] In another exemplary aspect of the invention, the integrated
optical coupler and housing arrangement 2 can include first and
second housing portions 10 disposed side-by-side, each of which has
an optical coupler portion 4 integrally formed therewith. This
configuration allows both a light emitter and a light detector, for
example, to be disposed in the same assembly, therefore saving
circuit board space. The respective housing portions can be
manufactured separately and joined together, for example, or the
two housing portions can be integrally molded together.
[0081] Referring also to FIGS. 9 and 10, the front end of the
integrated optical coupler and housing arrangement 2 may also be
provided with an electromagnetic interference shield 16. The
electromagnetic interference shield 16 is preferably formed from a
conductive, non-corrosive material, such as steel having a tin
plating. However, the electromagnetic interference shield 16 can be
formed of any material that will attenuate electromagnetic
interference.
[0082] As shown, the electromagnetic interference shield 16 is
hollow, to allow the shield 16 to be slipped over the front end of
the integrated optical coupler and housing arrangement 2. When
properly positioned, the edge of the electromagnetic interference
shield 16 will be positioned essentially flush with the front end
of the housing portion 10. The shield 16 may be provided with
inwardly projecting fingers 16' that engage with the surface of the
housing portion 10, to hold the shield 16 in place.
[0083] Preferably, the electromagnetic interference shield 16 is
provided with a number of conductive grounding springs 17, which
are disposed around the outer periphery of an end of the shield 16.
As shown in FIG. 11, the grounding springs 17 engage, for example,
with a tailstock 17' attached to a system frame 17" of a computer,
for example, to conductively couple the electromagnetic
interference shield 16 to a ground potential. When properly
positioned, the grounding springs 17 hold the electromagnetic
interference shield 16 in a fixed position relative to the
tailstock 17'.
[0084] By way of example, the grounding springs 17 can be formed as
metal fingers which extend in the same plane, and contiguous with,
a respective wall of the shield 16. The metal fingers can then be
bent so that the fingers are disposed essentially superposed to the
respective walls they are attached to. However, due to the memory
effect of the material, the fingers will exert a spring force that
acts in a direction away from the walls. Thus, the metal fingers
can engage with the tailstock, in the aforementioned manner.
[0085] In the illustrated exemplary embodiment, the shield 16 can
be used to hold the first and second housing portions 10 together,
when two separate housing portions are provided. That is, the
shield 16 can be slid around the adjacent housing portions 10, and
serve as a clamp to retain the housing portions in their relative
positions.
[0086] In an exemplary aspect of the invention, the integrated
optical coupler and housing arrangement 2 forms a component of an
optical transceiver arrangement 18 that includes a plurality of
other interconnected subassemblies, the details of which will be
described in the paragraphs that follow.
[0087] For example, one of the subassemblies of the optical
transceiver arrangement 18 is a carrier assembly. As best shown in
FIGS. 12 and 13, the carrier assembly includes a die carrier 19,
having opposing lands 20. In the exemplary illustrated embodiment,
the opposing lands 20 have a receiving space therebetween, in which
either the light emitter die chip 6 or the light detector die chip
is disposed.
[0088] The carrier 19 may be manufactured from a conductive
material, so that it can serve as a ground for the die chip 6. For
example, the carrier 19 can be formed from copper, and be gold
plated to enhance its conductivity and reduce its susceptibility to
oxidation. However, it is contemplated that the carrier 19 can be
manufactured from other materials without departing from the spirit
and scope of the invention.
[0089] In another exemplary aspect of the invention, the carrier 19
has spaced apart feet 24, which can be attached to a further
subassembly of the optical transceiver arrangement, as will be
subsequently described. The feet 24 provide a space under the
carrier 19 in which other components can be disposed. Moreover, the
feet 24 are shown as being in registration with the lands 20.
However, variations in the relative placement of the feet 24 and
lands 20 are within the scope of the invention.
[0090] The lands 20 are adapted to allow the optical coupler
portion 4 to be attached thereto. For example, each land 20 can be
provided with a receiving and alignment hole 28. Further, each
opposing end surface 7, 7' of the optical coupler portion 4 may
have an alignment pin or pins 30 that projects therefrom (see FIG.
1). In the illustrated exemplary embodiment, each end surface 7, 7'
has a pair of alignment pins 30 disposed to flank the optical
fibers 8. The alignment pins 30 on one end surface 7 are received
within corresponding receiving and alignment holes 28, to align and
fix the optical coupler portion 4 to the die carrier 19. The
alignment pins 30 on the other end surface (see FIG. 6) are
insertable within corresponding holes formed in the fiber optic
connector, to align and fix the optical coupler portion 4 to the
fiber optic connector.
[0091] In the exemplary illustrated aspect of the invention, the
lands 20 are adapted to project out beyond the die chip 6. This
configuration prevents the optical coupler portion 4 from having
direct contact with the active regions (i.e., the regions that emit
or detect the light) of the die chip 6.
[0092] The optical fibers 8 of the optical coupler portion 4 may be
actively aligned with the active regions, so as to ensure that the
emitted light does not partially or completely "miss" its intended
target. By way of example, with the alignment pins 30 received with
a clearance fit in the respective receiving and alignment holes 28,
and with a 12-channel light emitter (i.e., a light emitter having
12 active regions), the light emitter may be turned on (activated).
The first optical fiber of the optical coupler could then be
aligned, in both an x- and a y-direction, with the center of the
first channel. The optical coupler portion 4 could then be rotated
about the z-axis of the first channel, until the maximum output of
the twelfth channel is ascertained. Thereafter, a UV curable
adhesive, for example, could be used to fix the respective
alignment pins 30 in the respective receiving and alignment holes
28 in the lands 20, thereby locking the optical coupler portion 4
in alignment with the active regions of the die chip 6.
[0093] After alignment, an epoxy, for example, can be used to seal
the exterior edges of the optical coupler portion 4 to the surface
of the die chip 6. The epoxy may have a sufficiently high viscosity
so as to prevent the epoxy from flowing into the gap between the
front edge of the optical coupler portion and the active regions of
the die chip 6. Thus, a sealed air gap will be formed between the
ends of the optical fibers 8 in the optical coupler portion 4 and
the active regions to allow for the efficient transmission of
light, while preventing contaminants from entering this space.
[0094] In a further exemplary aspect of the invention, the carrier
assembly includes a flex cable 40 that is electrically coupled to
the die chip 6. In the exemplary illustrated embodiment, the flex
cable 40 has a ground layer (hereinafter referred to as ground
wires) and signal wires (shown in hidden lines, and referenced as
41 in Figure) which may be covered by an insulating coating 41',
such as plastic. The insulating coating 41' may be removed in a
region at one end of the flex cable 40, to form one or more windows
42 which expose the signal wires, grounds wires, or both as they
pass through the space of the windows 42. For example, if the flex
cable 40 is provided with two windows 42, one disposed over the
other (not shown), the lower window can be adapted to expose the
ground wires, so that the exposed ground wires may be electrically
coupled to the conductive carrier 19. The upper window can then be
adapted to expose the signal wires, which can then be electrically
coupled to the die chip 6. This arrangement works well when the die
chip 6 is attached and directly grounded to the carrier 19. For
example, the back of the light emitter die chip 6 may be bonded to
the carrier 19 using an electrically-conductive epoxy, so that the
light emitter die chip 6 is grounded directly to the conductive
carrier 19. Alternatively, if the die chip 6 is not directly
grounded to the carrier 19, then the flex cable 40 can be provided
with only one window, which is adapted to expose both the ground
wires and the signal wires. These can then be electrically coupled
to the die chip 6, for example a light detector die chip 6, to
provide both a signal path and a return ground path.
[0095] By way of example, the signal wires and the ground wires of
the flex cable 40 may be electrically coupled to the carrier 19
and/or die chip 6 using a so-called tab bonding technique. Such a
technique is well known to those skilled in the art, and includes
using pressure, heat and vibrations to ultrasonically weld the
components together. Moreover, a wire-bond conductive ball (not
shown) may be used to couple the signal wires to the die chip 6.
For example, the wire-bond ball may be connected to tab bonds of
the die chip 6. The wire-bond ball may be coined down (i.e.,
flattened), to provide a smooth, flat surface to which the signal
wires may be bonded. By bonding the signal wires to the wire-bond
balls, as opposed to a surface of the die chip 6, the surface of
the die chip 6 is protected against damage that may otherwise occur
during the tab bonding technique. The tab bonds may then be covered
with a chip-coat protective adhesive, for example, to protect the
connection.
[0096] Another end of the flex cable 40 may be provided with a
conductive plate 44, such as a metal stiffener plate, electrically
bonded to the ground wires/ground plane of the flex cable 40. This
conductive plate 44 can then be easily attached to a ground
potential, in a manner that will be subsequently described.
[0097] In use, the flex cable 40 may be arranged to extend down the
front of the carrier 19 (i.e., on the side the die chip 6 is
disposed), and then flexed and bent to pass between the feet 24 of
the carrier 19 and through the space therebetween. Thus, when in
use, the conductive plate 44 will be disposed in a region behind
the carrier 19.
[0098] Referring also to FIGS. 14-17, in a further exemplary aspect
of the invention, the optical transceiver arrangement further
includes a laminate assembly 56. The laminate assembly 56 includes
a wiring board 58, that includes a plurality of superposed,
alternating conductive layers and insulating layers formed in
discrete planes. Although the individual layers are not separately
shown, such arrangements are known to those skilled in the art. In
the exemplary illustrated embodiment, the wiring board 58 is a
relatively flat board having a front surface that has various
electronic components 59, such as a light emitter driver chip
and/or light detector driver chip attached thereto, and having
electrically conductive pathways or wirings (also known as traces)
between the respective components. Preferably, the driver chips are
positioned so that in the completed optical transceiver
arrangement, the driver chips are positioned away from the carrier
19 to aid in heat dissipation.
[0099] By way of example, the conductive layers may include one or
more internal wiring planes (i.e., a set of wirings located in one
plane), each of which includes a number of individual conductive
wirings. As mentioned above, the wirings are used to interconnect
the various electronic components 59 locatable on the wiring board
together, and allow for the transmission of electrical signals.
[0100] Further, the conductive layers of the board 58 may also
include one or more power planes and/or ground planes, which are
typically sheets of conductive material, such as copper. The power
plane is used to supply power from the wiring board 58 to the
various electronic components 59 located on the wiring board,
whereas the ground plane serves as a ground potential for the
various electronic components 59. The power plane and the ground
plane may be located in different planes from the wiring plane, or
may be located in the same plane as a respective wiring plane.
[0101] Each of the conductive layers of the wiring board 58 may be
separated from the other overlying and/or underlying conductive
layers by a respective layer of insulating material. Moreover, the
wiring board 58 may be provided with a number of plated
mechanically-formed through holes and/or a number of plated
mechanically-formed vias (i.e., blind holes formed in the
insulating layers and plated or filled with a conductive material).
Each plated via and plated through hole is electrically coupled to
a respective conductive layer, and is used to transmit power or
electrical signals, through respective insulating layers, to and
from the associated electronic components 59 and/or between the
respective conductive layers. Further, the vias, for example, can
be used to interconnect the ground plane and wiring plane to
respective conductive pads 60 formed on the surfaces of the wiring
board 58.
[0102] The wiring board 58 can be adapted to allow its attachment
to a further printed circuit board 61 (see FIG. 11), such as a
backplane, for example, by an end user. By way of example, the
lower surface of the wiring board 58 can be provided with a
plurality of conductive pads 60 arranged in an array (not shown),
each of which is coupled to the ground plane, power plane and/or
wiring plane, using the vias, for example, and each of which may be
attached to a respective lead of the printed circuit board 61 using
ball grid array (BGA) technology, for example. Although not shown,
such technology is well known to those skilled in the art.
[0103] The laminate assembly 56 may also include a polymer, for
example, coating 62 disposed on the upper surface of the wiring
board 58, and upon which the housing portion 10 can be disposed.
The polymer coating 62 may be relatively thick and formed to
provide locating features to facilitate the positioning of the
various other subassemblies. For example, the housing portion 10
may be provided with one or more projecting pins 63 on a lower
surface thereof (see FIG. 18), and the polymer coating 62 may be
provided with receiving holes 63' that accommodate the respective
projecting pins 63. Thus, the integrated optical coupler and
housing arrangement 2 can be quickly located on the laminate
assembly 56 in a desired position. Moreover, the coating 62
protects the wirings and components on the surface of the wiring
board 58, and helps to distribute heat generated by the drivers
over a larger surface area.
[0104] Moreover, the polymer coating 62 may be provided with one or
more recesses formed therein. In the illustrated exemplary
embodiment, a relatively large recess may be formed in a central
region of the coating 62, to expose signal and/or power traces 63"
that are coupled to the wiring plane and/or power plane, and to
expose one or more conductive pads 60 that are electrically coupled
to the ground plane. The feet 24 of the carrier 19 can then be
electrically bonded, using an electrical epoxy for example, to the
exposed conductive pads 60 electrically coupled to the ground
plane, so that the carrier 19 is likewise electrically coupled to
the ground plane. Moreover, the conductive plate 44 of the flex
cable 40 may be electrically bonded to another conductive pad, to
provide another means of electrically coupling the ground plane to
die chip 6 and carrier 19. Further, the signal wires of the flex
cable 40 may be coupled, for example wire bonded, to the respective
signal and/or power traces 63" on the surface of the wiring board
58. Thereafter, the various electrical connections can be coated to
protect the connections and wires from being damaged. For example,
the coating can be a so-called chip coat epoxy material.
[0105] During the coupling of the flex cable 40 to the wiring board
58, the housing portion 10 may also be fixed to the laminate
assembly 56. For example, the housing portion 10 may be epoxied to
the laminate assembly 56.
[0106] As shown in FIG. 19, the optical transceiver arrangement may
also include a heat sink cover, which is disposed over the laminate
assembly 56 (best shown in FIGS. 4 and 5). In this exemplary aspect
of the invention, the polymer coating 62 includes a step arranged
around an outer periphery thereof, and the heat sink cover 64 has a
flange that engages with the step to position the heat sink cover
relative to the laminate assembly 56. Once in position, the heat
sink cover 64 can transfer and dissipate heat generated by the
drivers, for example.
[0107] The heat sink cover 64 may also be formed from an
electrically conductive material and be provided with a
downwardly-projecting finger 66 that is adapted to engage with an
exposed conductive pad 60 of the wiring board 58, which is coupled
with the ground plane. In this manner, when the heat sink cover 64
is in position, the heat sink cover 64 will be electrically coupled
with a ground potential, allowing the heat sink cover to serve as a
further ground potential for the light emitter/light detector.
Moreover, the downwardly-projecting finger 66 can be positioned to
extend between the first and second housing portions 10, and
between the respective light emitter and light detector (when so
provided), to serve as an electromagnetic emissions separator. For
example, the finger 66 can extend through the gap 67, as shown in
FIG. 2. Thus, the heat sink cover 64 can help to prevent
electromagnetic interference from occurring between the light
emitter and the light detector.
[0108] Once properly positioned, and referring back to FIG. 5, the
heat sink cover 64 is bonded in place, for example using an epoxy,
and will preferably be positioned to abut against a back of the
housing portion 10. Moreover, in an exemplary aspect of the
invention, a gap 68 is present between the back of the carrier 19
and the heat sink cover 64, which is subsequently filled with a
thermal epoxy 69. The thermal epoxy 69 provides for improved
conductivity between the carrier 19 and the heat sink cover 64.
This gap 68, which may be 0.005 inches, for example, can be
established using ears 70 which project from a rear of the
respective housing portions 10. The ears 70 abut against the heat
sink cover 64 when the heat sink cover, carrier 19, housing portion
10 and laminate assembly 56 are all properly joined together.
[0109] The present invention results in an optical transceiver
arrangement in which various delicate components are sealed and
protected. Moreover, the thermal characteristics are optimized,
resulting in increased efficiency. Further, optical clarity is
enhanced and the resulting structure can be easily assembled and
used in small spaces. Further, the arrangement allows for both a
transmitter and detector in the same package. Additionally, this
arrangement allows MPO and MTP optical connectors to be selectively
attached thereto. Further, the resulting optical transceiver
arrangement has fewer parts, thus reducing inventory and reducing
manufacturing time. Moreover, due to the elimination of a separate
optical coupler, the reliability of the resulting structure is
enhanced, since the optical coupler portion cannot shift or become
separated from the housing portion.
[0110] It should be understood, however, that the invention is not
necessarily limited to the specific arrangement and components
shown and described above, but may be susceptible to numerous
variations within the scope of the invention.
[0111] It will be apparent to one skilled in the art that the
manner of making and using the claimed invention has been
adequately disclosed in the above-written description of the
preferred embodiments taken together with the drawings.
[0112] It will be understood that the above description of the
preferred embodiments of the present invention are susceptible to
various modifications, changes, and adaptations, and the same are
intended to be comprehended within the meaning and range of
equivalents of the appended claims.
* * * * *