Optical waveguides – Accessories – External retainer/clamp
Reexamination Certificate
1998-04-23
2001-05-29
Arroyo, Teresa M. (Department: 2881)
Optical waveguides
Accessories
External retainer/clamp
C385S052000, C385S065000, C385S083000, C501S079000
Reexamination Certificate
active
06240235
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an optical fiber fixing member made of a glass and a method for producing the same. The present invention also relates to a mold being suitable for molding an optical fiber array partly composed of the optical fiber fixing member described above, an optical module partly composed of this optical fiber array and an optical fiber guide block made of a glass.
BACKGROUND ART
Optical fibers for use in optical communication are usually fine fibers made of a glass, quartz-based single mode optical fibers for use in a long distance optical communication being composed, for example, of a core portion with an outer diameter of about 10 &mgr;m and a clad portion with an outer diameter of 125 &mgr;m for coating the core portion. Quartz-based multi-mode optical fibers are composed of a core portion with an outer diameter of 50 to 125 &mgr;m and a clad portion with an outer diameter of 125 &mgr;m for coating the core portion. Accordingly, when optical fibers are optically connected with each other (the phrase “optically connect” is referred to “optical interconnection” hereinafter) or optical fibers are optically connected with optical element(s) such as an optical waveguide, a lens, an light emitting element and a light acceptance element, a highly precise alignment is required for reducing connection loss at the optical interconnection part. Especially, in the optical interconnection of the quartz-based single mode optical fibers with each other and optical interconnection of the quartz-based single mode optical fiber with a quartz-glass-based single mode optical waveguide, an alignment with an accuracy of as high as about ±1 mm is required.
When optical fiber(s) is/are optically connected with other optical fiber(s) or optical element(s), the optical fiber(s) is/are previously fixed in an optical fiber fixing tool such as an optical connector or optical fiber array. The optical fiber array as used herein is at least provided with an optical fiber guide block comprising a thin plate on which optical fiber fixing engagement portion(s) for fixing (positioning) the optical fiber(s) is/are formed, optical fiber(s) engaged to the optical fiber fixing engagement portion(s) and a holding block comprising a thin plate for compression-fixing optical fiber(s) engaged to the optical fiber fixing engagement portion(s).
For example, Japanese Unexamined Patent Publication No. Hei 7-5341 discloses an optical fiber array fixing a tape fiber produced by protecting given strings of optical fiber disposed in parallel relation with each other with a coating material comprising a resin. As shown in
FIG. 26
, the optical fiber array
200
disclosed in the foregoing patent publication is provided with a thin plate of an optical fiber guide block
204
on which a given number of V-shaped grooves
203
as optical fiber fixing engagement portions for fixing optical fibers
202
exposed from a tape fiber
201
, optical fibers
202
and a thin plate of an optical fiber holding block
205
for compression-fixing the optical fiber
202
engaged to the V-shaped grooves
203
described above. The optical fiber guide block
204
constituting this optical fiber array
200
has a pedestal
207
for fixing the coated optical fiber
206
in the tape fiber
201
besides the V-shaped grooves
203
described above, the pedestal
207
being formed by one step lower than the V-shaped grooves
203
. The optical fiber array
200
is also provided with a coated optical fiber holding block
208
with a given cross sectional configuration for compression-fixing the coated optical fiber
206
fixed on the pedestal
207
.
An active alignment using a precision stage has been applied in the optical interconnection of the optical fibers fixed in optical fiber fixing tools such as an optical connector or optical fiber array with each other, or in the optical interconnection of the optical fiber(s) fixed in the optical fiber fixing tool and optical element(s) with a high alignment accuracy as described previously. This active alignment is executed, for example, in the mutual connection of the optical fibers fixed in optical fiber arrays as follows.
After fixing one optical fiber array (referred to “optical fiber array A” hereinafter) on which optical fiber(s) is/are fixed to one holder on the precision stage, the other optical fiber array (referred to “optical fiber array B” hereinafter) on which optical fiber(s) is/are fixed is fixed to the other holder on the precision stage. Then, a light beam is allowed to irradiate the optical fiber fixed with the optical fiber array A from the tip of the optical fiber, positioned at an opposite end to the optical end face (of the side faces of an optical fiber array, a side face positioned at the optical interconnection side where the optical fiber array is connected to the other optical fiber array or optical element: the same hereinafter). An optical detector is provided at the end of the optical fiber positioned at the opposite side of the optical end face in the optical fiber array B. The precision stage is then scanned in a wide range to search the position where any faint optical power is detected with the optical detector (this stage is referred to “first step”). The precision stage is finely scanned thereafter so that the optical detector senses the maximum optical power level, thereby completing the desired high accuracy alignment (this stage is referred to “second step”).
Since a long period of time is required for wide range scanning at the first step of the active alignment described above, it is desirable that the first step is substantially completed at the stage when the optical fiber fixing tools are fixed on the holders described above for making a highly precise alignment easy. Accordingly, it is desirable to precisely adjust the locational accuracy of the optical fiber fixing engagement portion(s), measured with reference to the bottom face or side face of the optical fiber fixing tool, to a degree of about 1/1 or less of the core diameter of the optical fiber fixed in the optical fiber fixing tool, along with precisely adjusting the dimensional accuracy of the optical fiber fixing engagement portion(s) for fixing optical fiber(s) in the optical fiber fixing tool. In the optical interconnection of the quartz-based single mode optical fibers with a core diameter of about 10 &mgr;m with each other or in the optical interconnection between the quartz-based single mode optical fiber and quartz-glass-based single mode optical waveguide, for example, the locational accuracy is desirably 10 &mgr;m or less and the alignment will be made more easily when this locational accuracy is 5 &mgr;m or less.
Optical interconnection by a passive alignment is made possible by adjusting the locational accuracy described above to about {fraction (1/10)} or less of the core diameter of the optical fiber. The passive alignment refers to a method in which, with no need of irradiating an beam to optical fiber(s) or detecting an emission beam from optical fiber(s), an alignment of the optical fiber fixing tools with each other or an alignment between the optical fiber fixing tool and an optical element is carried out merely by a mechanical positioning by taking advantage of the bottom face or side face of the optical fiber fixing tool as a reference face.
The passive alignment may be possibly executed by providing alignment mark(s) with a high locational accuracy at desired position(s) of the optical fiber fixing tool, along with making use of a specified face of the optical fiber fixing tool as a reference face. Otherwise, a guide pin engagement portions with a high locational accuracy are provided at desired positions of the two members to be connected (optical fiber fixing tools with each other or an optical fiber fixing tool and an optical element) with each other, thereby the passive alignment can be carried out by an optical interconnection of the optical fibers with each other or by an optical interconnection between the optical fiber fixing tool
Hirota Shin-ichiro
Uno Ken
Yamashita Teruo
Yokoo Yoshiatsu
Yoshida Masahiro
Arroyo Teresa M.
Hoya Corporation
Leung Quyen P.
Nixon & Vanderhye P.C.
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