Optical waveguide module-mounted device

Details Optical waveguide module-mounted device Optical waveguide module-mounted device

2002-05-14

2004-01-20

Zarroli, Michael C. (Department: 2839)

Optical waveguides

With optical coupler

Particular coupling structure

C385S094000

Reexamination Certificate

active

06681068

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an optical waveguide module-mounted device which comprises a case and an optical waveguide module mounted in the case, the module being comprised of an optical waveguide chip and optical fibers connected to the chip. More particularly, the present invention relates to an optical waveguide module-mounted device used in the field of optical communication.
BACKGROUND OF THE INVENTION
RELATED ART
The recent development of optical communication technology has demanded optical waveguide module-mounted devices, such as optical branching elements and optical multiplexers, with higher cost performance and higher reliability. In general, the conventional optical waveguide module-mounted device is composed of an optical waveguide chip and optical fibers for optical input/output, connected to the terminal end surfaces of the optical waveguide chip.
When the optical waveguide module is put in use in communication system, it is generally necessary to protect the module by a package to enhance the reliability. The package provides resistance to external mechanical impact, thereby improving long-term reliability. When an optical waveguide is connected to optical fibers, a UV-setting resin is generally used as an adhesive for connection. It is known that the long-term adhesive property of the UV-setting resin is deteriorated due to intrusion of moisture. Therefore, it is of importance that the connecting portion of the optical waveguide module is protected by a case or similar means so that the connecting portion is not exposed to moisture (see Japanese Patent No. 3,070,028).
FIG. 1
shows a longitudinal cross section of a conventional optical waveguide module-mounted device, which comprises an optical waveguide module composed of optical fibers
1
and an optical waveguide chip
2
, connected in such manner that their axes are aligned with each other, and a cylindrical case
4
in which the module is fixed via element-fixing members
3
. The optical fibers
1
are fixed in position with optical-fiber lead-in members
5
. The optical fibers
1
and the optical waveguide chip
2
are enclosed by the cylindrical case
4
and the optical-fiber lead-in members
5
.
FIG. 2
shows a cross section of another conventional optical waveguide module-mounted device. An optical waveguide module comprising optical fibers
1
and an optical waveguide chip
2
, connected in such manner that their axes are aligned with each other, is fixed to a lower half case
6
(the case is formed of an upper half case and a lower half case) by resin
7
. The optical fibers
1
are fixed in position with optical-fiber lead-in members
5
, and the optical waveguide module-mounted device is sealed with the upper half case
8
of the upper-lower separation type case. The optical fiber
1
and the optical waveguide chip
2
are enclosed by the lower half case
6
and the upper half case
8
of the upper-lower separation type case and the optical-fiber lead-in members
5
.
The optical-fiber lead-in member
5
, used in conventional optical waveguide module-mounted devices as shown in
FIGS. 1 and 2
, is typically made of a flexible gummy resin, in order to enhance bending strength reliability of the optical fibers.
FIG. 3
shows a condition of the conventional device, when the optical fiber is bent. As shown in
FIG. 3
, even when the bending direction of the optical fiber
1
is changed by external force, the lead-in member
5
is flexible enough to absorb the bend, thereby maintaining bending strength reliability of the optical fiber.
However, the structure of the conventional optical waveguide module-mounted device shown in
FIG. 1
has problems in that, in order to fix the optical waveguide module comprised of the optical waveguide chip and the optical fibers connected to the chip to the inside of the cylindrical case, it is necessary to pass the optical waveguide module through the cylindrical case and the optical fibers through the optical-fiber lead-in members. In addition, for adhesion of the optical waveguide chip to the cylindrical-case via element-fixing members, special jigs are required due to the cylindrical shape. Further, the fixing portion cannot be visually checked from above the case and thus the workability becomes poor, resulting in additional working processes.
On the other hand, since the conventional optical waveguide module-mounted device shown in
FIG. 2
is in the form of a box comprising an upper half and a lower half, as compared with the conventional case shown in
FIG. 1
, this shape allows visual checking of the portion of fixing the optical waveguide module to the case from above, and the workability is improved, leading to less working steps. However, more parts are necessary in this device, resulting in higher cost and more assembling steps, and the resultant device becomes costly.
In order to solve the above-mentioned problems, the present inventors proposed an optical waveguide module-mounted device formed of upper-lower separation type case member in co-pending U.S. patent application Ser. No. 10/104594, filed on Mar. 27, 2002 (based on Japanese Patent Application No. 2001-089644), assigned to the same assignee, which is incorporated herein by reference). Specifically, as shown in
FIG. 4
, an optical waveguide module comprising optical fibers
19
and an optical waveguide chip
18
, connected in such manner that their axes are aligned with each other, is fixed to an optical waveguide-chip fixing groove of a lower half case
12
(the case is formed of an upper half case
11
and a lower half case
12
) by resin (for fixing optical waveguide chip)
22
. The optical fiber
19
is passed through an optical-fiber lead-in groove
13
and fixed in position by a sealant
21
. At an internal position of the case, the optical fiber is further fixed to an optical-fiber fixing groove
14
by a resin (for fixing optical fiber)
20
. The fixed fiber is sealed with the upper half case
11
. The optical fibers
19
and the optical waveguide chip
18
are enclosed by the upper half case
11
and the lower half case
12
.
Problems to be Solved by the Invention
In the case of the optical waveguide module-mounted device shown in
FIG. 4
, i.e. the device described in the prior application by the present inventors (U.S. patent application Ser. No. 10/104594), the case member is provided with the optical waveguide-chip fixing groove
17
, the optical-fiber lead-in portions
13
and the optical-fiber fixing grooves
14
, which is different feature from the conventional devices shown in
FIGS. 1 and 2
. With this multi-functional integrated upper-lower separation type case, the number of parts can be reduced and assemblage can be easily conducted. However, the multi-functional integrated upper-lower separation type case, used in the optical waveguide module-mounted device shown in
FIG. 4
, is generally made of a resin by injection molding or a metal by metal injection, from the viewpoint of lowering production cost. The resultant optical-fiber lead-in portion is rigid and hard. Therefore, the case has a problem in that, when the optical fibers are bent by external force at portions where the optical fibers are led out of the case, friction between the fiber and the case occurs, which may lower the quality of the optical fibers, resulting in low liability of the optical fibers.
In brief, the optical waveguide module-mounted device comprising the multi-functional integrated upper-lower separation type case shown in
FIG. 4
has advantages of reducing the number of parts. In addition, since the case is comprised of open half cases, it is allowed to visually check the portions of fixing the optical waveguide module to the case from above and below, and thus the workability is improved, leading to less working steps. However, the case also has disadvantages in that, since the optical-fiber lead-in portions are made of a rigid resin or metal, bending strength reliability of the optical fibers is lowered when the optical fibers are abraded by the rigid case at the

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