Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2003-02-03
2004-04-06
Lee, John D. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S089000, C385S090000, C385S091000, C385S092000, C385S094000
Reexamination Certificate
active
06715935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical module used in optical communications or data communications.
2. Description of the Related Art
An optical module in which an optical element mounting substrate for mounting optical elements are arranged in a package has been used in optical communications or the like. Recently, in order to meet a requirement to save cost for the optical module, an optical module whose package is made of resin has heretofore been developed.
FIG. 7A
is an exploded view of an optical module proposed in Japanese Patent Application No. Hei 9-007021 as an example of this type optical module.
FIG. 7B
is a perspective view of an example of an outer appearance of the optical module.
In the optical module
100
shown in
FIGS. 7A and 7B
, an array type optical element
1
in which, for example, light emitting portions or light receiving portions are arranged in an array is mounted on and fixed to an optical element mounting substrate
2
. A pattern of electric signal wirings
10
is formed on a mounting surface (substrate surface)
28
of this optical element
1
. Also, V-shaped grooves
9
(having a V-shape in cross section) as at least one pair of groove portions for positioning on the substrate side are formed on both sides with respect to the electric signal wirings
10
.
There are various kinds of the optical elements
1
. For example, there is a module in which a semiconductor laser chip having four channels for emitting an optical signal is arranged on a substrate, a module in which a photodiode chip for receiving an optical signal is arranged instead of the semiconductor laser chip, a module in which the semiconductor laser chip is arranged in the same manner and a photodiode chip for monitoring a light emission condition of the semiconductor laser chip is provided behind the semiconductor laser chip and the like. Among these optical elements, for example, the optical element that meets the specification is selected and mounted on and fixed to the optical element mounting substrate
2
.
A package
4
is made of resin to have a base portion
31
and a side wall
32
having a substantially L-shape (an L-shape in cross section) that is in an upright position at an end face of the base portion
31
. At least one (four in case of
FIG. 7A
) input/output optical fiber insertion hole
6
is formed in the side wall
32
of this package
4
.
Input/output optical fibers
7
are inserted into the input/output optical fiber insertion holes
6
, respectively. Each of the input/output optical fibers
7
is a short optical fiber for at least one of the optical input to the optical element
1
and the optical output of a beam outputted from the optical element
1
to the outside.
Further, a positioning projection
18
is formed in a position corresponding to each of the V-shaped grooves
9
of the optical element mounting substrate
2
in the package
4
. As indicated by the arrow B in
FIG. 7A
, the substrate surface
28
of the optical element mounting substrate
2
is caused to face the surface on which the projections
18
are formed in the package
4
, with the substrate surface
28
of the optical element mounting substrate
2
being directed downwardly (in FIG.
7
A), the optical element mounting substrate
2
is caused to overlap on the base portion
31
of the package
4
, and the projections
18
are inserted and fitted into the V-shaped grooves
9
.
FIG. 8
is a cross-sectional view showing an fitted condition of the projections
18
into the V-shaped grooves
9
. As shown in
FIG. 8
, the cross section of the projections
18
is formed into an arcuate shape at their ends, and the ends contact the groove surfaces of the V-shaped grooves
9
. Then, thus, the projections
18
are inserted and fitted into the V-shaped grooves
9
so that the package
4
and the optical element mounting substrate
2
are positioned with each other and the array type optical element
1
and the input/output optical fibers
7
are centered and optically coupled to each other.
Under the condition in which the optical element mounting substrate
2
and the package
4
are overlapped with each other as described above, the region (indicated by reference character A in
FIG. 7A
) between an inner wall surface
32
a
of the side wall
32
of the package
4
and the optical element
1
is sealed with resin. Thus, the input/output optical fibers
7
are bonded and fixed to the package
4
, at the same time, the optical element
1
of the optical element mounting substrate
2
as a whole is covered by the resin to be sealed. Furthermore, the optical element mounting substrate
2
is fixed to the package
4
.
The package
4
in which the optical element mounting substrate
2
is provided is mounted on a lead frame package
11
with the optical element mounting substrate
2
being directed downwardly as indicated by the arrow C in
FIG. 7A
, and fixed by adhesives
30
.
The optical module
100
shown in
FIGS. 7A and 7B
is constructed as described above. This optical module
100
is constructed so as to be electrically connectable to a circuit of a mounting substrate (not shown) through a plurality of lead terminals
17
formed in the lead frame package
11
.
Incidentally, reference numeral
20
in
FIGS. 7A and 7B
indicates an opening portion, which is a hole for wire bonding (lines made of gold are arranged from the optical element mounting substrate
2
to the lead frame package
11
) and injecting the adhesives
30
.
As described above, with the optical module
100
, only the projections
18
of the package
4
are inserted and fitted in the V-shaped grooves
9
of the optical element mounting substrate
2
so that the array type optical element I and the input/output optical fibers
7
are centered and optically coupled to each other. Thus, it is possible to provide the optical module that may optically and directly coupling the array type optical element
1
and the input/output optical fibers
7
with each other without any lens without using an expensive device.
However, although the resin made package
4
is molded by transfer molding, injection molding of the resin or the like, there is a problem in that it is technically difficult to form the projections
18
into a desired shape, for example, an arcuate shape having a diameter of about 125 &mgr;m.
Namely, in order to form the package
4
, as shown in
FIG. 9
, the resin forming the package
4
is caused to flow into a mold
33
having a groove
33
a
for forming the projection
18
and cured. At this time, in order to form the projection
18
to have an exact size and an exact shape, it is necessary to transfer the groove
33
a
of the mold
33
exactly with the precision of ±1 &mgr;m. In order to attain this, a high processing technique is required. Also, in view of the fact that it is difficult to exactly evaluate the dimension of the machined mold, it is difficult to enhance the dimensional precision of the mold
33
by feeding back the information of the dimensional error of the molded product.
For this reason, it is technically difficult to form the projection
18
with a high precision and exactly in accordance with the design as described above. Due to this, it is difficult to, precisely position the package
4
and the optical element mounting substrate
2
with each other. Accordingly, it is difficult to perform the precise positioning of the relative positional relationship between the optical element
1
and the input/output optical fiber
7
and to stably realize the high optical connection.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above, and an object of the present invention is therefore to provide an optical module in which an optical element mounting substrate and a package may be arranged exactly with each other.
In order to attain this and other objects, according to a first aspect of the invention, there is provided an optical module having an optical element mounting substrate on which an optical element is
Iwase Masayuki
Mori Hajime
Lee John D.
The Furukawa Electric Co. Ltd.
Valencia Daniel
LandOfFree
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