Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
2001-07-31
2004-06-08
Lee, John D. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S078000, C385S080000
Reexamination Certificate
active
06746160
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a preliminary member of an optical device component with optical fiber used to manufacture an optical device.
In recent years, with the rapid development of the optical communications network, high-quality and low-price optical devices have become necessary in bulk. In particular, in a plug type optical device or a receptacle type optical device with optical fiber built-in, a cylindrical optical device component in which an optical fiber is inserted into a precise capillary tube and fixed therein is used.
Priorly, as a component used in an optical device with optical fiber built-in, for example, an optical fixed attenuator, as shown in
FIG. 8
, an optical device component
5
is known, wherein an optical fiber
1
having a predetermined light signal attenuation factor is inserted into an inner hole
2
a
of a ceramic capillary tube
2
and fixed therein with an adhesive
4
, and both end faces
2
b
and
2
c
are processed to become convex spherical surfaces. In addition, as a component used in an optical device which emits or receives light signals, an optical device component
6
as shown in
FIG. 9
is known, wherein an optical fiber
1
is fixed in an inner hole
3
a
of a capillary tube
3
with the adhesive
4
, one end
3
b
is processed to become a convex spherical surface, and a light emitting element such as a semiconductor laser is connected to the other end
3
c
which has been diagonally polished.
The cylindrical optical device component
5
with the optical fiber
1
fixed as shown in FIG.
8
and
FIG. 9
has dimensional accuracy equivalent to that of a plug of an optical connector and is built in a housing
8
of an optical fixed attenuator provided with members having precisely aligning functions such as a receptacle
7
and a split sleeve. A plug end face of an optical connector
9
shown by a broken line, which has been processed to become a convex spherical surface, is butted against the end face of the optical device component
5
which has been processed to become a convex spherical surface in the housing
8
and physical contact (abbreviated as PC) connection where reflected light is suppressed on the connection end surface is achieved, where by making it possible to transmit light signals at a high speed.
However, in assembly of the optical device components
5
and
6
shown in FIG.
8
and
FIG. 9
, the adhesive
4
is infected into the inner hole
2
a
having an inside diameter slightly greater than the optical fiber
1
, thereafter a difficult operation is required such that while inserting the optical fiber, the adhesive
4
is uniformly filled in the gap between the inner hole
2
a
and optical fiber
1
so as not to create air bubbles and the like. Therefore, there is a problem in that skilled labor becomes necessary and since assembling capacity is in proportion to the number of workers, the cost becomes expensive.
In addition, in a case where a ceramic capillary tube is used as the optical device components
5
and
6
and the silica-based optical fiber
1
is fixed in the inner hole thereof, since the coefficient of linear expansion of the optical fiber
1
is 5×10
−7
/K, while the coefficient of linear expansion of the ceramic capillary tube is 1.1×10
−5
/K, that is greater by approximately two digits, protrusion and retraction phenomena occur on the end faces of the optical fiber
1
located at
2
b
,
2
c
,
3
b
, and
3
c
. With such phenomena, the intensity and phase of a light signal which propagates through the optical fiber
1
and other optical components connected thereto change, therefore, there is a problem in that connecting quality of the light signal is degraded.
In addition, in a case where a ceramic capillary tube is used as the optical device components
5
and
6
, when the end faces thereof are polished for PC-connecting with an optical connector, since the polishing speed on the ceramic capillary tube is slower than the polishing speed of the optical fiber
1
made of silica glass, it is necessary to use expensive diamond films and to use slurry which contains special abrasive grains and the like and requires advanced technical skill accumulation for handling.
In addition, since the ceramic capillary tube barely allows light of 1000 nm or more to penetrate therethrough, it is impossible to perform a flaw inspection of the optical device components
5
and
6
with optical fiber inserted and fixed therein by means of laser beams within the infrared region of 1000 nm or more.
Furthermore, the ceramic capillary tube barely allows light with a wavelength of 350 nm-500 nm, whereby photo-curing adhesive generally cures, to penetrate therethrough. Therefore there is also a problem in that photo-curing adhesive having sensitivity for ultraviolet rays to blue visible rays cannot be used.
In addition, the side of the optical device
5
to be connected to an optical connector is inserted into an adapter of the optical connector. In a case where a split sleeve made of zirconia has been built in the said adapter, if the ordinary glass optical device
5
is inserted, there is a fear that the glass surface of the optical device
5
will be damaged and the strength will be seriously degraded
In addition, it is necessary to insert the optical fiber whose covering has been removed in advance into the capillary tube, however, it is in practice difficult to almost completely remove the covering along the long length without breaking the fiber by means of an optical fiber stripper.
In addition, after the adhesive is filled into the capillary tube inner hole and the optical fiber is inserted, when the adhesive is cured, there is also a problem in that a contraction stress occurs in the adhesive and refractive index distribution of the optical fiber changes especially at the end portions of the long capillary tube.
In addition, after the adhesive is filed into the capillary tube inner hole and the optical fiber is inserted, when the adhesive is cured, there is also a problem in that the adhesive contracts and air bubbles generate.
For example, as shown in
FIG. 10
, in order to bring a light signal emitted from a laser diode
1
and condensed by the lens
2
into an optical fiber
4
inside an optical connector plug
3
or in order to condense a light signal emitted from the optical fiber
4
of the optical connector plug into a photodiode (not illustrated), a module as shown in the same drawing is used. In such a module, an optical fiber stub
5
with optical fiber
6
held in an inner hole
5
a
is used to bring in the light signal condensed by the lens
2
or for the signal to be emitted.
The end face
5
b
on the laser diode
1
(or photodiode) side of the optical fiber stub
5
is polished so that the end face
5
b
forms an angle of a few degrees with respect to the incident axis of the light signal to prevent reflected light from entering the laser diode
1
and becoming noise. Furthermore, the end face
5
c
on the other side is provided with a C-chamfer
5
d
on the peripheral portion to enable connection to an optical connector plug
3
and PC (a convex surface for physical contact) polishing around an optical fiber
6
as its center is provided.
These processes of the end faces
5
b
and
5
c
of the optical fiber stub
5
are performed, as shown in
FIG. 11
, by means of a special polishing device after the optical fiber
6
is fixedly fitted inside the inner hole
7
a
of a ferrule
7
composing the fiber stub
5
with adhesive
8
.
However, the ferrule
7
has a shape shown in FIG.
11
(A) and does not have a flare portion which guides the optical fiber
6
and eases insertion into the inner hole
7
a
. Therefore, in a case where the optical fiber stub
5
is assembled using the ferrule
7
, adhesive
8
is injected into the inner hole
7
a
having an inside diameter slightly greater than the optical fiber
6
, thereafter a difficult operation is required such that while looking through a microscope, the optical fiber
6
is carefully inserted an
Funabiki Nobuo
Horibe Syojirou
Iida Masanao
Nakajima Sotohiro
Takeuti Hirokazu
Arent & Fox PLLC
Lee John D.
Nippon Electric Glass Co. Ltd.
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