Optical waveguides – Accessories – External retainer/clamp
Reexamination Certificate
1999-03-05
2001-10-16
Font, Frank G. (Department: 2877)
Optical waveguides
Accessories
External retainer/clamp
C385S033000, C385S083000
Reexamination Certificate
active
06304708
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an optical fiber array constructed by arranging and fixing an optical fiber in a V-groove and a production method thereof.
Recently, with the densification of optical fibers, movement to multifilamantary planar waveguides (PLCs) has been accelerated. Furthermore, with the movement to multifilamantary planar waveguides, development has been advanced in the direction of shortening conventional standard pitches of the waveguides so as to avoid waveguide elements from upsizing and to achieve densification. Moreover, with the densification of optical fibers and shortening of waveguide pitches, pitches between fibers of optical fiber arrays that are connected to optical fibers have been also shortened in the development of fibers.
FIG. 9
shows an example of a half-pitched fiber array whose pitches each are shortened to a half of a conventional pitch.
In
FIG. 9
, a lower substrate
10
having a V-groove and a coated fiber housing substrate
15
are adhesively fixed with each other from above a step portion
12
of the lower substrate
10
. Coated fibers
13
a
and
13
b
are inserted with being piled in two levels from a coat housing groove
17
formed in the coated fiber housing substrate
15
, and respective fibers in lower and upper levels are alternately aligned in the V-groove. Next, by attaching an upper substrate (fiber presser substrate)
11
from above the V-groove of the lower substrate
10
and fixing the upper substrate
11
, an optical fiber array
22
is produced.
In the above case, after optical fibers are inserted between the upper and lower substrates, an ultraviolet hardening-type adhesive is injected into gaps of these upper and lower substrates and optical fibers. Next, ultraviolet rays are applied to harden the ultraviolet hardening-type adhesive and to fix the upper and lower substrates and optical fibers.
Although hardening of this adhesive is performed by applying ultraviolet rays to the adhesive, usually, the adhesive is hardened by applying the ultraviolet rays to the entire optical fiber array from above the optical fiber array.
Nevertheless, if the ultraviolet rays are applied to the entire optical fiber array as described above, the adhesive shrinks at the time of hardening. Therefore, since the adhesive over the entire optical fiber array is hardened at the same time, stress (distortion) corresponding to a product of the shrinkage of the adhesive used and the Young's modulus remains behind. This stress generates minute peeling within a boundary between the upper and lower substrates and adhesive, and this peeling may become a factor of degrading reliability from the long-term perspective. In addition, even if the peeling cannot be found, residual stress may exist with a high probability, and hence, such a state also has a possibility of becoming a factor raising a problem on long-term reliability.
Furthermore, in
FIG. 9
, a filling amount of a first adhesive between the lower substrate
10
and upper substrate
11
is largely different from that of a second adhesive injected into an upper gap (coat housing portion) of the step portion
12
that exists between the lower substrate
10
and coated fiber housing substrate
15
. In consequence, there was a problem that residual stress by the shrinkage at the time of the adhesive being hardened also becomes extremely large in a second adhesive portion.
SUMMARY OF THE INVENTION
The present invention is performed in consideration of such conventional problems. An object of the present invention is to provide an optical fiber array, which has no loss and excellent long-term reliability by suppressing residual stress in the optical fiber array as much as possible at the time of fixing an optical fiber with hardening adhesives, and a production method thereof.
According to the present invention, there is provided a production method of an optical fiber array comprising an upper substrate and a lower substrate where a V-groove is formed, the production method which comprises steps of inserting and arranging an optical fiber on the V-groove, fixing the upper substrate and the lower substrate with an adhesive, and fixing and aligning the optical fiber on the V-groove, wherein an ultraviolet hardening-type adhesive is hardened by applying ultraviolet rays to the V-groove in parallel from on an extension line of an optical fiber axis with the optical fiber being inserted and aligned between the upper and lower substrates and the ultraviolet hardening-type adhesive being injected into gaps between these upper and lower substrate and optical fiber.
In addition, the present invention provides a production method of an optical fiber array comprising an upper substrate, which is composed of a fiber presser substrate for pressing an optical fiber on a V-groove and a coated fiber housing substrate for housing an coated fiber, and a lower substrate where the V-groove is formed, the production method which comprises steps of inserting and arranging an optical fiber on the V-groove, fixing the upper substrate and lower substrate with an adhesive, and fixing and aligning the optical fiber on the V-groove, the production method further comprising sequential steps of: inserting and arranging the optical fiber between the upper and lower substrates; injecting the ultraviolet hardening-type adhesive into gaps between these upper and lower substrate and optical fiber; and hardening the ultraviolet hardening-type adhesive by applying ultraviolet rays to the V-groove in parallel from on an extension line of an optical fiber axis.
Furthermore, the present invention provides a production method of an optical fiber array comprising an upper substrate and a lower substrate where a V-groove is formed, the production method which comprises steps of inserting and arranging an optical fiber on the V-groove, fixing the upper substrate and lower substrate with an adhesive, and fixing and aligning the optical fiber on the V-groove, the production method further comprising sequential steps of: inserting and arranging the optical fiber between the upper and lower substrates; injecting an ultraviolet hardening-type adhesive into gaps between these upper and lower substrate and optical fiber, the ultraviolet hardening-type adhesive being composed of a first adhesive for bonding the optical fiber on the V-groove between the upper and lower substrate and a second adhesive for bonding the coated optical fiber between the upper and lower substrate, the first adhesive having a Young's modulus larger than the second adhesive; and hardening the ultraviolet hardening-type adhesive by applying ultraviolet rays to the V-groove in parallel from on an extension line of an optical fiber axis.
In the above method, it is preferable to harden the ultraviolet hardening-type adhesive by applying the ultraviolet rays in the direction from the bare optical fiber to the coated optical fiber. In addition, it is preferable that the optical fiber array is a half-pitched optical fiber array having two levels of coated optical fibers.
In addition, the present invention provides an optical fiber array which comprises an upper substrate, a lower substrate where a V-groove is formed, and optical fibers inserting and arranging on the V-groove, the upper substrate and the lower substrate being fixed with an adhesive, and the optical fibers being fixed and aligned on the V-groove, wherein the upper substrate comprises a fiber presser substrate for pressing the optical fibers on the V-groove and a coated fiber housing substrate for housing the coated optical fibers, and wherein a housing groove for coated-optical fibers and an adhesive inflow groove portion in the direction of a fiber axis are formed in the coated fiber housing substrate.
Furthermore, the present invention provides an optical fiber array which comprises an upper substrate, a lower substrate where a V-groove is formed, and optical fibers inserting and arranging on the V-groove, the upper substrate and the lower substrat
Fukuyama Masashi
Kurimoto Hironori
Burr & Brown
Font Frank G.
NGK Insulators Ltd.
Nguyen Sang H.
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