JPH0637367Y2 - Optical fiber array - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an optical fiber array in which one to a large number of optical fibers are aligned and fixed, and more specifically, an optical fiber element wire portion and a protective coating layer therefor. The present invention relates to an optical fiber array in which an optical fiber having a core wire portion covered with is aligned and fixed, and a thermal stress relaxation portion is provided between the element wire fixing portion and the core wire fixing portion of the optical fiber.

[Prior Art] In an optical transmission system, an optical fiber array is used for connecting optical fibers to each other or connecting an optical fiber and a planar waveguide.

As an optical fiber array of this type, for example, as shown in FIGS. 5 and 6, there is a configuration in which optical fibers are aligned and held by an alignment holding component in which a substrate 10 and a cover 12 are combined.

Here, the substrate 10 has an optical fiber element 14
Has a plurality of precision alignment grooves (V grooves) 16 for aligning the optical fibers, and a recess for accommodating the optical fiber core portion 18 in the rear.
The cover 12 has a structure in which 20 is formed, and the cover 12 has a through hole 22 for injecting an adhesive in the center thereof.

The substrate 10 and the cover 12 may be an integrally molded product made of plastic, but since the thermal expansion coefficient of the plastic is large, the tip end surface of the optical fiber element wire part is the end surface of the substrate or cover due to the expansion of the groove portion due to temperature change. The problem of transmission loss occurs. Therefore, processed products of glass and ceramics are often used in accordance with the demand for higher performance.

Use a jig to fix the optical fiber.
Are aligned in the precision alignment groove 16 and, at the same time, the optical fiber core 18
After storing it in the recessed part 20, covering the cover 12 and temporarily fixing it,
This is done by pressing in a resin adhesive from a through hole 22 formed in the center of the cover 12.

[Problems to be Solved by the Invention] However, in the above-described conventional optical fiber array, when a substrate or cover made of glass or ceramics is used, the thermal expansion coefficient of the resin adhesive is higher than that of the resin expansion coefficient. The coefficient is 6 to 10 times or more, and there is a problem that the transmission characteristics fluctuate due to temperature changes, and at high temperatures (for example, 80 ° C or higher), the resin adhesive deteriorates and the adhesive strength decreases, resulting in peeling between the substrate and cover. There were serious problems such as the occurrence.

Particularly in the case of an optical fiber array using an optical fiber having a wire portion and a core portion coated with a protective coating layer,
Due to the difference in thermal expansion coefficient between the wire fixing portion and the core wire fixing portion, there is a problem that the optical fiber element wire portion is broken.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to have high assembly accuracy, good temperature characteristics, and stable optical fiber that does not cause peeling of the substrate or breakage of the optical fiber even at high temperatures. To provide an array.

[Means for Solving the Problems] An optical fiber array according to the present invention has an alignment groove for aligning and accommodating an optical fiber element wire portion, and the optical fiber element wire portion and it are covered with a protective coating layer. It comprises a lower substrate on which the optical fiber core wire portion is mounted and an upper substrate for holding the aligned optical fiber element wire portion.

In order to achieve the above object, in the present invention, the upper substrate is transparent and the upper and lower substrates are made of glass or ceramics, and the alignment groove of the lower substrate accommodating the optical fiber element wire and the upper substrate are Fill the gap with solder and fix it,
The optical fiber core wire portion is fixed by a core wire holding board different from the upper board, and the optical fiber wire wire portion is loosened between the wire holding portion by the upper board and the core wire holding portion by the core wire holding board. As a structure in which they are arranged and covered with an epoxy resin protective film, a stress relaxation portion for relaxing the difference in coefficient of thermal expansion between the wire fixing portion and the core fixing portion is provided, and these points are characteristic.

As the solder used here, for example, a Pb-Sn-Zn system or a Pb-Sn-Sb system which can fix glass or ceramics is preferable.

When the number of aligned optical fibers is small, a dummy groove may be further provided on the lower substrate or the upper substrate, and solder may be filled in the dummy groove to increase the fixing strength.

[Operation] The optical fiber is housed in the alignment groove formed on the lower substrate without pre-metallizing the wire,
It is fixed by pressing it with the upper substrate and filling the gap between the alignment groove and the upper substrate with solder. At this time, since the upper substrate is transparent, the filling of the solder can be visually confirmed. For this reason, it is possible to firmly adhere while maintaining the highly accurate arrangement state. Further, since the substrate and the solder have the same coefficient of thermal expansion, the one having high thermal stability can be obtained.

Further, the core wire portion is fixed independently of the wire wire portion, and the core wire fixing portion and the wire wire fixing portion are apart from each other, so that a stress relaxation portion for relaxing the stress due to the difference in thermal expansion coefficient is formed between them.
It is possible to alleviate the pull-in and the protrusion due to the thermal expansion of the core portion in the wire-fixing portion to prevent breakage of the optical fiber and breakage or peeling of the substrate.

[Embodiment] FIG. 1 shows an embodiment of an optical fiber array according to the present invention. A is a front view, B is a side sectional view, and C is a plan view.

This optical fiber eyelet 30 has a precision alignment groove 34 having a V-shaped cross section for aligning and accommodating the optical fiber elemental wire portions 32 on the upper surface of the tip portion, and a V for aligning the optical fiber core wire portion 36 on the upper surface of the substrate portion. It is provided with a lower substrate 40 having a groove 38, an upper substrate 42 for pressing the aligned optical fiber element wire portions 32, and a core wire holding board 44 for fixing the optical fiber core wire portion 36, and they are separated from each other. A space between the upper substrate 42 and the core-portion holding substrate 44 serves as a stress relaxation portion for relaxing stress on the wire fixing portion.

The lower substrate 40 and the upper substrate 42 are made of glass or ceramics, and the upper substrate 42 is a transparent body. Core wire holding board 44
May be stainless steel, Kovar, or float glass. Precision alignment groove 34 and V groove 38 of lower substrate 40
Is machined at high density using a dicing saw.
Then, in the gap between the precision alignment groove 34 of the lower substrate 40 accommodating the optical fiber bare wire portion 32 and the upper substrate 42, the glass ceramic solder 46 is placed.
Are fixed by filling them using an ultrasonic soldering device. At this time, since the upper substrate 42 is transparent, the filling of solder can be confirmed.

The optical fiber core wire portion 36 is arranged in the V groove 38 of the lower substrate 40, sandwiched by the core wire portion holding substrate 44, and fixed by a heat resistant adhesive 48 having a thermal expansion coefficient equivalent to that of the material of the protective coating layer.
The stress relaxation portion between the upper substrate 42 and the core portion pressing base 44 is arranged by slackening the optical fiber element wire portion, and the exposed portion (curved portion) of the optical fiber element wire portion has a low Young's modulus or a substrate. A heat-resistant adhesive 48 (epoxy resin) having a coefficient of thermal expansion close to is covered with a thin protective film.

The actual assembly is performed as follows. First the parts to use,
In particular, the parts to be fixed with solder should be thoroughly washed so that no organic matter remains (residual primary coat, etc.). For example, it is desirable to perform ultrasonic cleaning in the order of acetone, alcohol, pure water and the like. Further, it is desirable that the optical fiber bare wire portion 32 is further subjected to ozone cleaning after the above-mentioned treatment.

It is possible to efficiently perform the temporary alignment of the optical fibers by using an assembling apparatus as shown in FIG. The optical fiber bare wire portion 32 is sandwiched between the precision alignment groove 34 of the lower substrate 40 and the upper substrate 42, and temporarily fixed by a pressing jig 50 with high accuracy. Similarly, the optical fiber core wire portion 36 is connected to the core wire portion V groove 38 of the lower substrate 40 and the core wire portion holding board.
It is clamped by 44 and temporarily fixed by a holding jig 52.
Then, the preheater 54 provided at the tip portion preheats the tip portion at a temperature about 20 to 30 ° C. lower than the melting temperature of the solder.
While preheating, solder the glass ceramics solder 46 with the ultrasonic soldering iron 56 to the precision alignment groove 34 of the lower substrate 40 and the upper substrate 42.
Fill the gaps and fix them. At this time, the work can be performed while confirming that the upper substrate 42 is filled with the solder.

Subsequently, the exposed part of the optical fiber strand (stress relaxation part)
A heat resistant adhesive having a coefficient of thermal expansion equivalent to that of the lower substrate 40 is applied to form a protective film, and the optical fiber core portion is bonded and fixed. Finally, the optical fiber array is completed by polishing the tip surface.

Cerasolzer # as a solder for glass ceramics in the prototype
186, # 246 (trade name: manufactured by Asahi Glass Co., Ltd.) and the like were used. A heat-resistant epoxy resin having a small coefficient of thermal expansion is used for the protective film of the exposed portion (stress relaxation portion) of the optical fiber element. In the prototype, Epotech 353ND (trade name: manufactured by Epoxy Technology Co., Ltd.) with SiO ₂ as a filler is used
A coating containing 50% by weight was used and applied to the minimum necessary thickness.

FIG. 3 shows another embodiment of the optical fiber array according to the present invention. A is a front view, B is a side sectional view, and C is a plan view. This embodiment is particularly effective when the number of optical fibers is small (for example, one or two). Since the basic structure is similar to that shown in FIG. 1, corresponding parts are designated by the same reference numerals for simplification of description. In this embodiment, two optical fibers are used.

When the number of optical fibers is small, the number of precision alignment grooves 34 formed on the lower substrate 40 is also small and the adhesive strength may be insufficient. Therefore, in such a case, a dummy groove 58 is provided, and the dummy groove 58 is also filled with solder to fix the lower substrate 40 and the upper substrate 42 together. In this example, the lower substrate
One dummy groove 58 is provided on each side of the tip portion of 40.
However, the number of dummy grooves is arbitrary, and may be provided on the lower surface of the upper substrate instead of the lower substrate, or may be provided on both the lower substrate and the upper substrate. The optical fiber bare wire portion 32 is housed in the precision alignment groove 34 of the lower substrate 40 and pressed by the upper substrate 42, and fixed by filling the gap between the precision alignment groove 34 and the upper substrate 42 with solder 46. In addition, the dummy groove 58 and the upper substrate 42
The gap 46 is filled with the solder 46, and the lower substrate 40 and the upper substrate 42 are firmly fixed to each other.

FIG. 4 shows still another embodiment of the present invention, which is an example in which the optical fiber core wire portion is fixed by "caulking" instead of adhesion. Since this embodiment is basically the same as that shown in FIG. 1, the corresponding parts are designated by the same reference numerals,
A description thereof will be omitted.

Here, as an example of a pressing member for the optical fiber core wire portion 36, a pressing metal member 6 having a substantially inverted U shape is used, and the pressing metal member is fixed by "caulking" by applying force in the direction of arrow P. Note that in FIG. 4B, a protective film is not drawn on the exposed portion (stress relaxation portion) of the optical fiber element wire portion between the upper substrate 42 and the pressing metal fitting 60 for the sake of easy understanding of the drawing. As in the above example, it is covered and protected with a heat resistant adhesive.

If transparent bodies are used for the lower substrate 40 and the upper substrate 42 in the present invention as in the above-mentioned embodiment, it is possible to visually confirm whether or not the solder has sufficiently penetrated during the solder filling, so that the reliability of the fixation is improved. This is preferable because the cost is high, the soldering time is not longer than necessary, and the resin coating of the optical fiber core portion is not melted or deformed.

Since the exposed portion (stress relaxation portion) of the optical fiber wire between the upper substrate 42 and the core wire holding board 44 is covered with a protective film of a heat-resistant adhesive, the optical fiber wire is affected by the humidity in the air. The strength of the parts is prevented from becoming inferior.

In each of the above-mentioned embodiments, the precision alignment groove for the optical fiber wire portion and the V groove for the optical fiber core wire portion are formed on the same lower substrate. The present invention can also be applied to a structure in which a lower substrate having precision alignment grooves and a holder having a storage portion for the optical fiber core portion are combined.

[Advantages of the Invention] As described above, the present invention is configured such that the lower substrate and the upper substrate are made of glass or ceramics, and solder is filled and fixed in the gap between the upper substrate and the alignment groove of the lower substrate accommodating the optical fiber strands. Therefore, it is needless to say that the alignment accuracy of the optical fiber wire portions can be increased, and the matching of the thermal expansion coefficients of the upper and lower substrates and the solder becomes extremely good. In the present invention, solder is used to join the lower substrate with the optical fiber strands aligned and the transparent upper substrate that covers it, so that the substrate does not peel even at high temperatures and the solder filling is visually observed. As a result, solder filling with high accuracy and good quality can be performed.

Further, in the present invention, since the core wire fixing portion is provided independently and the stress relaxation portion for relaxing the stress due to the heat change of the core wire fixing portion is provided, an excessive thermal stress is not applied to the wire fixing portion. An optical fiber having excellent thermal stability and excellent temperature characteristics can be obtained. No breakage of the optical fiber due to protrusion due to the difference in the coefficient of thermal expansion does not occur, and reduction in transmission loss due to pulling does not occur.

[Brief description of drawings]

1A is a front view showing an embodiment of an optical fiber array according to the present invention, FIG. 1B is a side sectional view thereof, FIG. 1C is a plan view thereof, and FIG. 2 is an example of its assembling apparatus. FIG. 3A is a front view showing another embodiment of the present invention, FIG. 3B is a side sectional view thereof, FIG. 3C is a plan view thereof, and FIG. 4A is still another embodiment of the present invention. 4B is a perspective view thereof, FIG. 5 is a perspective view showing an example of the prior art, and FIG. 6 is a sectional view thereof. 30 …… Optical fiber array, 32 …… Optical fiber bare wire, 34
…… Precision alignment groove, 36 …… Optical fiber core wire, 40 …… Lower board, 42 …… Upper board, 44 …… Core wire holding board, 46 …… Solder, 48 …… Heat resistant adhesive.

Continuation of front page (56) Reference JP-A-60-256107 (JP, A) JP-A-62-19811 (JP, A) JP-A-55-156908 (JP, A) JP-A-54-91246 (JP , A) Actually opened 58-18215 (JP, U) Actually opened 59-131709 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. An alignment groove for accommodating an optical fiber element wire portion, and a lower substrate on which the optical fiber element wire portion and an optical fiber core wire portion covering the optical fiber element wire portion are mounted are aligned. In an optical fiber array comprising an upper substrate that holds down the optical fiber strand portion, the upper substrate is transparent and the upper substrate and the lower substrate are made of glass or ceramics, and the lower substrate that houses the optical fiber strand portion is The gap between the alignment groove and the upper substrate is filled with solder and fixed, and the optical fiber core wire portion is fixed by a core wire holding board that is different from the upper board. The optical fiber element wire section is slackened between the fixing section and covered with an epoxy resin protective film to reduce the difference in thermal expansion coefficient between the element wire fixing section and the core wire fixing section. An optical fiber array provided with a stress relieving portion.