Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
2003-02-26
2004-12-07
Prasad, Chandrika (Department: 2839)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S088000
Reexamination Certificate
active
06827501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical comunication part including an optical element and a holder which calks the element therein. The present invention relates to a fabricating method of an optical communication part having an optical element fixed by caking in a hollow portion of a holder.
2. Prior Art
Some optical communication part are used with optical elements fixed within hollow holders. Such parts include optical communication equipment, measuring apparatuses, optical sensors and laser devices and the like, and further, such optical elements may include lenses, mirror reflectors, waveguides, optical isolators, and optical fibers or the like. Mechanical properties, for example, tensile strength, air-tightness and solder wettability are required for the above described parts.
According to a conventional art, in the optical communication equipment many optical communication parts have been used with optical elements fixed by calking in holders or ferrules. For example, Japanese Patent Publication No. 2-262607 discloses a method for calking a cylindrical lens within a holder.
However, it may be not sufficient that the optical element is fixed within the holder without using a curable bond material but only by using calking. For example, in the case where a spherical lens and a holder have different thermal expansion coefficients, even at a temperature when using an apparatus, a gap may be formed between the lens and the holder. This involves such a defect that the lens is deviated out of position, which doses not provide a desired optical property.
Japanese Patent Publication No. 2001-290049 discloses an optical communication part having an optical fiber fixed by calking to a ferrule which is shaped in a cylinder of a metal material plastically deformable and mechanically machinable by processing such as cutting. In
FIG. 22A
, within the ferrule, a glass fiber in an optical fiber
127
made of quartz glass from which a two-layered coating
128
has been removed in advance is inserted in the ferrule, and part of an outside of the ferrule
125
is deformed by adding compression from the outside toward a center thereof to calk the glass fiber
127
directly.
U.S. Pat. Re. No. 36231, as shown in
FIG. 22B
, discloses a structure in which the shapes of an optical fiber
126
and the ferrule
125
to be used are the same as that of
FIG. 22A
, except that upon fixing by calking a front end of the ferrule
125
is pushed in an axial direction by a upsetting die
129
having a tapered inner surface, resulting in the front end
134
of the ferrule
125
to be deformed in a tapered form to calk the optical fiber core
127
directly therein.
On the other hand, a structure is also suggested to fix by calking the optical fiber in the ferrule with a buffer material interposed between the ferrule
125
on the inside and the fiber core
127
to be calked. In a structure shown in
FIG. 22C
as an example of the above, at first, a coating
128
at the front end portion of an optical fiber
126
is removed, and then, the exposed optical fiber core
127
is inserted through the ferrule
125
. Japanese Patent Publication No. 2000-304968 discloses that a ferrule
125
is formed in a stepped form which is provided with a fiber core insertion hole
130
having inserted therethrough the fiber core
127
and with a coating insertion hole
131
having inserted therethrough a first coating
128
a
of the optical fiber
126
. This structure is further provided with a coating calk portion
32
for calking the first coating
128
a
, and the optical fiber
126
is fixed via the first coating
128
a
by deforming the coating calk portion
132
.
FIG. 22D
shows that the coating
128
is compressed between the back end of the ferrule and the optical fiber in addition to fixing by the direct calking of the fiber core
127
at the front end of the ferrule as shown in FIG.
22
B. At first, in the same manner as the above, the fiber core
127
from which the coating
128
has been removed in advance is inserted through the stepped-formed ferrule
125
and through a core insertion hole
130
at the front end of the ferrule and the coating is inserted through a coating insertion hole
131
at a rear end of the ferrule, after which the front end
134
around the fiber core and the rear end
135
of the ferrule
125
covering the coating
128
are calked respectively.
In the conventional techniques, as described above, a ferrule and a fiber core of optical fiber were directly calked, and, in calking, the outside of the ferrule was locally pressurized. However, it was very difficult in substance to deform the ferrule
125
uniformly by the force from its outer periphery. Even if the optical fiber
126
could be fixed to the ferrule, a gap was often formed between the ferrule and the fiber core which cannot ensure airtightness therebetween. On the contrary, where a calking amount is increased to secure airtightness, a crack tends to be generated in the fiber core by a calking strain directly produced thereto.
In the case of the structure as shown in
FIG. 22B
, it was possible to deform the front end of the ferrule
125
by the upsetting die
129
having a tapered inner shape, achieving airtightness easily, but a stress tended to be concentrated only on the front end
134
when the ferrule
125
was calked by the upsetting die
129
, because the front end face of the ferrule
125
before calking was flattened at right angle to the periphery of the ferrule. Accordingly, the deformation amount of the ferrule
125
must be very minute, and the calked length
133
in
FIG. 22B
was not more than 0.1 mm, decreasing strength against tension between the ferrule
125
and the optical fiber
126
.
Since the cross section of the front end
34
of the ferrule
125
was shaped flat, a friction force (contact resistance) against the die was so large when pressing the die
129
to the ferrule
125
that a force was not effectively transmitted in a direction toward an axis of the ferrule for calking the fiber core
127
, with the ferrule
125
stressed along the axis thereof, resulting in an external diameter of the ferrule
125
to be expanded. Where the external diameter of the ferrule
125
was expanded, in installing the optical part in communication equipment, an optic axis thereof was deviated from that of its counterparts, preventing the parts from optical connecting.
In the next place, in the case of the structure as shown in
FIG. 22C
, when installed the part in communication equipment, the part was fixed to the other part mainly by soldering or YAG laser welding in which a high temperature was provided to the coating
28
a
through the ferrule
125
and the coating
128
a
sometimes melted to drop out the optical fiber
126
therefrom.
Because the coating
128
a
was of synthetic resin such as polyacrylate or polyvinyl chloride, the coating had a negative impact on the peripheral parts due to outgassing from the coating
128
a
in communication equipment in which the part was installed. In addition, the coating
128
a
was easily deteriorated by absorption of water at a high temperature and a high humidity, and was expanded or contracted due to the temperature change, the optical parts having a problem of lowering of strength and reliability to the parts. Further, variation of thickness in the coating
128
a
changed a gripping force after calking, which makes strength unstable.
In the structure as shown in
FIG. 22D
, although airtightness was ensured by directly calking the optical fiber core
127
at the front end
134
of the ferrule
125
and the tensile strength at the front end side was compensated by calking the coating
28
at the rear end
135
of the ferrule
125
, when installing the optical part in communication equipment the coating
128
melted by heat in soldering or YAG laser welding in the same manner as the above described disadvantage and therefore the tensile strength of the optical fiber
26
was not secured.
SUMMARY OF THE INVENTION
The
Morooka Takayoshi
Takimoto Toshihiro
Yasuda Toshimichi
Hogan & Hartson LLP
Kyocera Corporation
Prasad Chandrika
LandOfFree
Optical communication part and method of fabricating the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical communication part and method of fabricating the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical communication part and method of fabricating the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3329008