JP3018536B2 - Ultrasonic welding type for star coupler and its production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, 2 ^m × having an input fiber ends 2 ^m the functioning as input channels (m ≧ 2), and an output fiber ends 2 ^m book functions as an output channel The present invention relates to a 2 ^m channel star coupler and an ultrasonic welding type suitable for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 24 is a schematic diagram showing an example of a star-type optical data link system according to the background art of the present invention. In this star type optical data link system, as shown in the figure, four terminals A to D are mutually connected by a star coupler SC of 4 × 4 channels. That is, the star coupler SC, is provided with four input channels are connected to the transmission section TX _A ~TX _D terminal to D. Also, if the output channel is 4
One is provided, it is connected to the receiver unit RX _A to Rx _D terminal to D.

For this reason, when an optical signal S is transmitted from a certain terminal, for example, the terminal A, the optical signal S is not only received at each of the terminals BD, but also at the terminal A.
Can be received.

FIG. 25 shows an example of a star coupler SC having the above function. As shown in the figure, in this star coupler SC, the mixing rod 1
A large number of plastic fibers 2 and 3 at both ends 1a and 1b
Are optically coupled. Therefore, when an optical signal related to predetermined information is input to one of the plastic fibers 2, the optical signal related to the information is branched and output from each plastic fiber 3. That is, in the star coupler SC, the plastic fiber 2 functions as an input channel, and the plastic fiber 3 functions as an output channel.

[0005]

By the way, in the above conventional example, the star coupler SC is formed by the mixing rod 1 and the plastic fibers 2 and 3 having different thermal expansion coefficients.
Therefore, when the ambient temperature of the star coupler SC changes, the characteristics of the star coupler SC change greatly. This is because the rate of expansion (or contraction) of the mixing rod 1 due to the change in the ambient temperature is different from that of the plastic fibers 2 and 3. Further, since the mixing rod 1 and the plastic fibers 2 and 3 are merely optically coupled, the plastic fibers 2 and 3 may be displaced from the mixing rod 1 by vibrating the star coupler SC. However, there is a problem that the rod may be separated from the mixing rod 1. Therefore, star coupler S
The use environment conditions of C will be significantly restricted. In particular, when constructing a star-type optical data link system in a car with a large environmental temperature difference and severe vibration,
This is the main bottleneck.

Further, each of the terminals A to D is connected from the star coupler SC.
The optical distance (fiber length) to is not always constant and may vary widely. Therefore, in order to cope with such a case, considering the optical loss in the plastic fiber 3 connecting the mixing rod 1 of the star coupler SC and each of the terminals A to D, the branching ratio of the star coupler SC is set to a value corresponding to each distance. Star coupler S so that
It is desired to configure C. However, the star coupler SC shown in FIG. 25 cannot satisfy the demand due to its structure.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its first object to provide a highly versatile 2 ^m × 2 ^m channel star coupler which has a moderate use environment.

A second object of the present invention is to provide an ultrasonic welding type suitable for manufacturing the star coupler according to the first object.

[0009]

According to a first aspect of the present invention, there is provided an optical branching portion formed by welding intermediate portions of two plastic fibers to each other, and the optical branching portion. An optical element having first and second input fiber ends extending from one end of the portion and first and second output fiber ends extending from the other end of the light branching portion is formed by combining two optical elements. The intermediate portions of the first output fiber ends are welded to each other, and the intermediate portions of the second output fiber ends are welded to each other to form an optical branching portion.
Have been.

According to a second aspect of the present invention, in order to achieve the first object, 2 ⁿ (n) channels functioning as input channels are provided.
An input fiber ends ≧ 2), is constituted by two combining 2 ⁿ × 2 ^n-channel star coupler and an output fiber ends 2 ⁿ present which functions as an output channel, one of 2 ⁿ × 2 ^n-channel While the middle part of the output fiber end of the star coupler corresponds one-to-one with the middle part of the output fiber end of the other 2 ⁿ × 2 ⁿ channel star coupler,
The light branch portions are formed by being mutually welded.

According to a third aspect of the present invention, the first and second plastic fibers are made of a first and a second plastic fiber in an integrated state.
The intermediate portions, the first intermediate portions of the third and fourth plastic fibers, the second intermediate portions of the first and third plastic fibers, and the second intermediate portions of the second and fourth plastic fibers. 2 While holding the intermediate portions in contact with each other, at least the first and second
An ultrasonic welding type for transmitting ultrasonic vibration applied to one of the welding type members to each contact portion and ultrasonically welding the first to fourth plastic fibers to each other, In order to achieve a second object, the first welding-type member has a pair of convex portions arranged to face each other with a concave portion therebetween, and the second and first plastic fibers are provided on one convex portion. A first groove portion which is finished so as to be able to fit the first intermediate portion in this order, and a second groove portion which is finished so as to be freely engageable with the first intermediate portion of the fourth plastic fiber; The second intermediate portion of the second and fourth plastic fibers is engaged with the second intermediate portion of the first plastic fiber in such a manner that the second intermediate portion of the second and fourth plastic fibers can be freely fitted in this order. And a fourth groove portion is provided. 2 of the welding-type member has a pair of convex portions disposed opposite each other across the recess, the one of the convex portion, the first
A fifth groove portion finished to be freely engageable with the first intermediate portion of the plastic fiber, and a sixth groove finished so as to be able to fit the first intermediate portion of the third and fourth plastic fibers in this order. While the groove portion is provided, the other convex portion,
The seventh groove portion finished so as to be freely engageable with the second intermediate portion of the fourth plastic fiber and the second intermediate portion of the third and first plastic fibers are finished so as to be freely fitted in this order. An eighth groove is provided.

[0012]

According to the first and second aspects of the present invention, the respective intermediate portions of the plastic fiber are welded to each other so that the light is
A branch portion is formed to form a star coupler. Therefore, sufficient strength against vibration can be obtained. In addition, the component parts of the star coupler are made of only plastic fibers, thereby preventing a change in the characteristics of the star coupler due to a temperature change.

According to the third aspect of the present invention, the first and the second
Are integrated, the first and second intermediate portions of the first to fourth plastic fibers are brought into contact with each other in a predetermined relationship. When the ultrasonic vibration is applied to at least one of the first and second welding members, the ultrasonic vibration is applied to each contact portion via the first and second welding members. As a result, the first to fourth plastic fibers are welded to each other at the contact portion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an optical element which is a component of the star coupler according to the present invention will be described, and then the structure of the star coupler will be described in detail.

A. Configuration of Optical Element FIG. 1 is a schematic view showing a procedure for manufacturing an optical element. Here, the manufacturing procedure of the optical element 10 will be described, and the features of the configuration will be clarified.

First, two plastic fibers F ₁ ,
F ₂ is prepared, and the plastic fibers F ₁ and F ₂ are arranged in parallel as shown in FIG. This process may be performed manually by an operator or by a suitable mechanical device.

Then, the intermediate portions (regions surrounded by dotted lines) of the plastic fibers F ₁ and F ₂ are welded to each other over a predetermined length. Thus, as shown in FIG. (B), and the optical splitter 11, and one plastic fiber from the end 11a F _1, F ₂ in the longitudinal direction X extending fiber ends 12 _a, 12 _b of the optical splitter 11, Direction X from the other end 11b
The extending fiber ends 13 _a, 13 a _b are formed.

[0018] Thus the optical device 10 is manufactured, for example, if you enter a light signal S to the fiber ends 12 _a, respectively branched from the optical signal S is fiber ends 13 faces the fiber end 12 _{a a,} 13 _b Is output.

As the welding method, a conventionally well-known thermal welding method or a prior application filed by the present applicant (Japanese Patent Application No. 2-1755).
No. 4), there is an ultrasonic welding method, and any method may be used.

<Heat Welding Method> For example, the above-mentioned welding by the heat welding method is performed using a welding die 40 shown in FIG. 2 and a heat welding device 50 shown in FIG. Hereinafter, an example of the configuration of the welding die 40 and the thermal welding device 50 and an example of a thermal welding procedure will be described.

As shown in FIG. 2, the welding mold 40 is composed of first and second welding mold members 41 and 42 finished in a shape that can be fitted to each other. The first and second welding-type members 41 and 42 are provided with grooves (symbols omitted) extending in the X direction. Therefore,
While engaging the plastic fibers F ₁ and F ₂ extending in the X direction with the grooves, the first and second welded members 4 are joined.
When the members 1 and 42 are fitted to each other, as shown in the figure, the intermediate portions of the plastic fibers F ₁ and F ₂ are held in contact over the length Maki.

As shown in FIG. 3, the heat welding device 50 is provided with an electromagnetic heating mechanism 51, which extends from a plate 52 of the electromagnetic heating mechanism 51 in a direction perpendicular to the direction X. It is configured such that the welding die 40 can be held by the metal welding type holder 53. Therefore, simultaneously with the operation of the electromagnetic heating mechanism 51, the welding type holder 53 and the welding type 40 are heated, and the heat is applied to the contact portions of the plastic fibers F ₁ and F ₂ via the welding type 40.

Further, the heat welding device 50 is provided with a pressure applying mechanism (not shown) for applying a predetermined pressing force from above to the upper surface 53a of the welding type holder 53. Therefore, when the pressure applying mechanism operates, a predetermined pressing force is applied to one plastic fiber F ₁ via the welding type holder 53 and the first welding type member 41, and the plastic fiber F ₁ is applied to the other plastic fiber F _1. It is pressed against the fiber F _2.

Next, the heat welding procedure will be described. An operator arranges the plastic fibers F ₁ and F ₂ substantially in parallel as shown in FIG. Then, when a production start command is given via an operation panel (not shown) of the heat welding device 50, first, the plastic fibers F ₁ and F ₂ are held by the welding mold 40 (FIG. 2). Following that,
The pressure applying mechanism is operated, a predetermined pressing force is applied to the welding type holder 53, and the plastic fibers F ₁ and F ₂ are pressed against each other. Then, the welding unit 53 and the welding mold 40 are heated in a state where the electromagnetic heating mechanism unit 51 is operated and a predetermined pressing force is applied to the press-contacting unit, and the heat is transmitted through the welding mold 40 to the plastic mold. Fiber F ₁ ,
It is given to the press-contact portion of the F ₂ together. As a result, the press contact portions are welded to each other, and the light branching portion 11 is formed. After the completion of the heat welding, the electromagnetic heating mechanism 51 and the pressure applying mechanism are stopped in response to a stop command from the control unit, and a cooling device (not shown) is operated to bring the temperature of the welding mold 40 and the like to room temperature. Force cool them until they are.

<Ultrasonic Welding Method> Next, the above-mentioned welding by the ultrasonic welding method will be described.
In the ultrasonic welding method, the welding die 40 and the ultrasonic welding device 6 are used.
0 (FIG. 4) is used. As shown in FIG. 4, the ultrasonic welding device 60 is provided with an ultrasonic welding mechanism 61, and the vibrator 62 of the ultrasonic welding mechanism 61 is attached to the upper surface 41 b of the first welding mold member 41. Has been abutted. Therefore, simultaneously with the operation of the ultrasonic welding mechanism 61, the vibrator 62
Is ultrasonically vibrated in the Y direction orthogonal to the X direction, and the vibration energy is applied to the contact portions of the plastic fibers F ₁ and F ₂ via the first welding type member 41.

Further, the ultrasonic welding device 60 is provided with a pressure applying mechanism (not shown) for applying a predetermined pressing force to the ultrasonic welding mechanism 61. Therefore, when the pressure applying mechanism operates, a predetermined pressing force is applied to the plastic fiber F ₁ via the ultrasonic welding mechanism 61 and the vibrator 62, so that one plastic fiber F ₁ becomes the other plastic fiber F _2. Is pressed against.

Next, the procedure of ultrasonic welding will be described. As in the case of the above-mentioned heat welding, the operator arranges the plastic fibers F ₁ and F ₂ substantially in parallel. Then, when a production start command is given through an operation panel (not shown) of the ultrasonic welding device 60, first, the plastic fibers F ₁ and F ₂ are held by the welding mold 40 (FIG. 2). Subsequently, the pressure applying mechanism is operated, a predetermined pressing force is applied to the ultrasonic welding mechanism 61, and the plastic fibers F ₁ and F ₂ are pressed against each other. Then, the ultrasonic welding mechanism 61 is operated, and the vibration energy is applied to the press-contact portion between the plastic fibers F ₁ and F ₂ while a predetermined pressing force is applied to the press-contact portion. As a result, the press contact portions are welded to each other, and the light branching portion 11 is formed. Finally, when the partial welding of the plastic fibers F ₁ and F ₂ is completed, the ultrasonic welding mechanism 61 and the pressure applying mechanism stop in response to a stop command from the control unit.

By the way, the optical element 10 manufactured as described above has a distribution ratio equal to or close to that as shown in the earlier application (JP-A-2-17554). By manufacturing the optical element 10 according to the procedure described above, the distribution ratio can be largely changed.

FIG. 5 is an explanatory diagram for explaining the manufacturing procedure. The difference between this manufacturing procedure and the manufacturing procedure by the ultrasonic welding method described above is that the plastic fiber F
_{While 1} is arranged so as to extend straight in the longitudinal direction X, in that the input side of the plastic fiber F _2, i.e. the fiber end 12b are arranged at an angle θ with respect to the plastic fiber F _1. In particular,
For example, it can be performed by disposing the plate member 43 shown in the same figure on the left front of the welding die 40 and inserting the fiber ends 12a and 12b into the through holes 43a and 43b formed in the plate member 43, respectively. The angle θ can be arbitrarily set by adjusting the distance between the through holes 43a and 43b and the distance at which the plate member 43 is disposed from the welding mold 40. The other manufacturing procedures are the same as the above manufacturing method. Therefore, the description thereof is omitted.

FIG. 6 is a schematic view of the optical element manufactured as described above. Here, the relationship between the angle θ and the distribution ratio was examined using a conventionally known ray tracing method. That is, while changing the angle θ, the output ratio of the optical signal output from the fiber ends 13a and 13b when the optical signal was input to the fiber end 12b was calculated. The following table shows the results.

[0031]

[Table 1]

It can be seen from the table that the distribution ratio greatly changes with the change of the angle θ. Thus, by adjusting the angle θ, the distribution ratio of the optical element 10 can be set to an arbitrary value.

Therefore, as an example, the optical characteristics of the optical element 10 at an angle θ (= 18.5 °) manufactured according to the above manufacturing procedure under the following conditions will be verified. The conditions are as follows: (pressing force) = 3 kgf (vibration frequency) = 15 kHz (vibration amplitude) = 40 μm (vibration application time) = 0.3 second (welding mold length) = 5 mm (compression rate) = 92.5 %. The compression ratio is expressed by the following equation (compression ratio) = (D
/ D ₀ ) × 100 where D is the fiber F ₁ (F
₂ ) The diameter of D, D ₀ is the fiber F before ultrasonic welding.
₁ (F ₂ ).

The characteristics of the optical element 10 manufactured as described above were evaluated using an optical power measurement system (not shown). Specifically, an optical power measurement system (numerical aperture N.
A. = 0.2) (light intensity = 18.0μ)
W) is input to the fiber ends 12a and 12b of the optical element 10, while the fiber end 1
3a and 13b are directly received, and the output value P
₃ to P ₄ were measured respectively. Further, the distribution ratio and excess loss were determined based on the data thus obtained. The following table summarizes the results.

[0035]

[Table 2]

B. Next, first to third embodiments of the star coupler according to the present invention will be described. Also in this case, similarly to the description of the optical element 10 described above, the manufacturing procedure of the star couplers 70, 80, and 90 according to the first to third embodiments will be described below, respectively, and the characteristics of their configurations will be clarified. .

<First Embodiment> FIGS. 7 to 9 show a first embodiment of the star coupler according to the present invention.
It is a schematic diagram for explaining an Example. Star coupler 7
In manufacturing the optical element 0, first, the optical elements 10a and 10b manufactured as described above are prepared, and the optical elements 10a and 10b are arranged in parallel (FIG. 7). Then, the intermediate portions of the fiber ends 13a of the optical elements 10a and 10b are welded to each other by the above-mentioned thermal welding method or the above-mentioned ultrasonic welding method (FIG. 8). As a result, a light branching portion 71 is formed, and a fiber end 72 extending from the light branching portion 71 in the longitudinal direction X of the plastic fiber.
a, 72b are formed. Similarly, the intermediate portions of the fiber ends 13b of the optical elements 10a and 10b are
They are welded to each other (FIG. 9) to form a light branching portion 73 and fiber ends 74a and 74b. Thus, 2 the ^two fibers ends 12a serving as an input channel, 12
b, 12a, 12b and ^two fiber ends 72a, 72b, 74a, 74b functioning as output channels.
2 ² × 2 ^2-channel star coupler 70 is formed with and. The fiber ends 12a, 12b, 12
It goes without saying that the fiber ends 72a, 72b, 74a and 74b may function as input channels while the a and 12b function as output channels.

Second Embodiment FIGS. 10 to 12 are schematic views for explaining a second embodiment of the star coupler according to the present invention. In manufacturing the star coupler 80, first, the 2 ² × 2 ^2- channel star coupler 70 manufactured as described above is used.
a and 70b, and prepare the star couplers 70a and 70b.
b are arranged in parallel (FIG. 10). Then, as shown in FIG. 11, the intermediate portions of the fiber ends 72a are welded to each other by the above-mentioned thermal welding method or the above-mentioned ultrasonic welding method.
As a result, an optical branch portion 81 is formed, and a fiber end portion 82 extending from the optical branch portion 81 in the X direction.
a, 82b are formed. Similarly, the fiber ends 74a, the fiber ends 74b, and the fiber ends 72b are welded to each other at their intermediate portions, and the optical branching portions 83, 85, 8 as shown in FIG.
7 is formed. Thus, the input channels (or output channels) to function as two ^three fiber ends 1
2a, 12b, ... and, 2 ^three fiber ends functions as an output channel (or input channels) 82
^{a, 82b, 2 3 × 2} 3 -channel star coupler 80 having ... and are formed.

Third Embodiment FIGS. 13 to 15 are schematic diagrams for explaining a third embodiment of the star coupler according to the present invention. In producing the star coupler 90 is first prepared as described above 2 ³ × 2 ^3-channel star coupler 80a,
80b are prepared, and the star couplers 80a and 80b are arranged in parallel (FIG. 13). Then, as shown in FIG. 14, the intermediate portions of the fiber ends 82a are welded to each other by the above-mentioned thermal welding method or the above-mentioned ultrasonic welding method. As a result, a light branching portion 91a is formed, and fiber ends 92a and 92b extending from the light branching portion 91a in the longitudinal direction X of the plastic fiber are formed.
Similarly, the corresponding fiber ends are welded to each other at their intermediate portions to form light branch portions 91b to 91h as shown in FIG. Thus,
2 having two ^four fiber end portions 12a which functions as an input channel (or output channels), 12b, ... and, 2 ^four fiber end portions 92a which functions as an output channel (or input channels), 92b, the ... a
^{A 4} × 2 ^4- channel star coupler 90 is formed.

<Other Examples> In the above, 2 ² × 2 ² , 2 ³ × 2 ³ , 2 ⁴
Although the * 2 ⁴ channel star couplers 70, 80 and 90 have been described, the present invention is not limited to the above. That is, as in the first to third embodiments, first, 2 ⁿ (n ≧ 4) input fiber ends that function as input channels and 2 ^{n that} function as output channels.
A 2 ⁿ × 2 ⁿ channel star coupler having two output fiber ends is provided. And the first through third
Similar to the embodiment, and an intermediate portion of the output fiber ends of one of the 2 ⁿ × 2 ⁿ intermediate portion of the output fiber ends of the channel star coupler and the other 2 ⁿ × 2 ^n-channel star coupler, a one-to-one Weld each other while making them correspond. Thus, a 2 ^{n + 1} × 2 ^{n + 1} channel star coupler can be manufactured.

C. Next, the operation of the star coupler 70 according to the first embodiment will be described with reference to FIG. Star coupler 70
Is a 2 ² × 2 ² channel type, in which four fiber ends 12b, 12a, 12a, 12b function as input channels (or output channels) and four fibers function as output channels (or input channels). It has ends 72a, 72b, 74a, 74b. Therefore, for convenience of the following description, the fiber end 1
2b, 12a, 12a, with referred 12b from the upper side of the drawing forward as soon as first to fourth channels CH ₁ to CH _4, fiber end 72a, 72b, 74a, 74b, respectively fifth through eighth channels CH ₅ ~ It is referred to as a CH _8.

As shown in the figure, the first channel CH ₁
If the input optical signals S ₁ from the light signals S ₁ is guided to the optical splitter 11a, is branched into optical signals S _2, S _3.

Then, one optical signal S ₂ is transmitted to the optical branching portion 7.
1 and is split into optical signals S ₄ and S ₅ and output to the fifth and sixth channels CH ₅ and CH ₆ , respectively.
Further, the optical signal S ₃ is guided to the optical branching portion 73 and the optical signal S _3
6 is branched into S _7, the seventh and eighth channel C
Output to H ₇ and CH ₈ respectively.

Each of the optical signals S _{2 to} S ₇ has a different intensity depending on the branching characteristic (distribution ratio) of each optical branch portion, but the information content is the same as the information of the optical signal S _1. is there. Accordingly, in the star coupler 70, the optical branching portion 11a, 11b, by setting the branching characteristics of the 71 and 73 suitably, the channel CH ₅ to CH ₈
The intensity of the optical signal output from the optical coupler can be adjusted to an arbitrary ratio, that is, the distribution ratio of the star coupler 70 can be controlled.
For example, according to the procedure shown in FIG.
In the case where the optical branching portion is formed such that each optical branching portion of 0 has an appropriate distribution ratio (= 9: 1), the distribution ratio of the star coupler 70 is 81: 9: 81 as shown in FIG. 9: 1
Becomes That is, if the input optical signal intensity 100 from the first channel CH ₁ ignoring light loss in the star coupler 70, the optical signal distribution ratio 9: 1 optical splitter 11
According to a, the optical signal is branched into an optical signal having an intensity of 90 and an optical signal having an intensity of 10. Then, one optical signal (intensity 90) is guided to the optical branching portion 71, and is branched into an optical signal of intensity 81 and an optical signal of intensity 9, and the fifth and sixth channels CH ₅ , CH ₅ ,
Output to CH ₆ respectively. Also, the light branching portion 11a
The optical signal of intensity 10 branched and output from the
Is divided into an optical signal of intensity 9 and an optical signal of intensity 1,
And the eighth channel CH ₇ and CH ₈ .

In the above, the case where the distribution ratio is set arbitrarily has been described, but it is also possible to make all the intensities substantially equal. The branching characteristics of the light branching portion are changed not only by changing the angle θ as described above, but also by changing the length of the light branching portion, changing the pressing force at the time of welding, and the like. .

[0046] Further, even when the input optical signal to a channel other than the channel CH _1, the same manner as above, the optical signal having the same information as the input optical signal from the four channels facing the input channel Are respectively distributed and output.

The operation of the star couplers 80 and 90 according to the second and third embodiments can be easily inferred from the operation of the star coupler 70, and a description thereof will be omitted.

D. Specific Example Next, after sequentially verifying the characteristics of the uncrosslinked polymethyl methacrylate-based plastic fiber star coupler 70 in which the optical branch portion was formed by the ultrasonic welding method and the thermal welding method, and further manufactured by the ultrasonic welding method The characteristics of the star couplers 80 and 90 made of uncrosslinked polymethyl methacrylate-based plastic fiber will be verified.

The inventor of the present application formed the optical branch portions 11a, 11b, 71 and 73 by ultrasonic welding under the following conditions in order to manufacture the star coupler 70 by ultrasonic welding. That is, the conditions are as follows: (pressing force) = 10 kgf (vibration frequency) = 15 kHz (vibration amplitude) = 40 μm (vibration application time) = 0.5 second (length of welding mold 40) Maki = 20 mm.

The characteristics of the star coupler 70 manufactured by the ultrasonic welding method were evaluated using an optical power measuring system. Specifically, an LED light having a wavelength of 660 nm emitted from the light source of the optical power measurement system (light intensity P ₁ = 15.4 μW)
The inputs to the first channel CH ₁ of the star coupler 70. On the other hand, the light emitted from the fifth through eighth channels CH ₅ to CH ₈ opposite to the first channel CH ₁ is received directly, the output value P ₅ to P for each channel CH ₅ to CH _8
8 were measured respectively. As a result, the output values P _{5 to} P ₈ were 2.8 μW, 2.5 μW, 4.1 μW, and 2.7 μW, respectively, and the distribution ratio was 1.1: 1.0: 1.6: 1.1. The excess loss LS in this case is:

[0051]

(Equation 1)

Was as follows.

Next, the 2 ² × 2 ² channels in the case of forming a star coupler by thermal welding star coupler 70
Will be described.

The inventor of the present application has verified the characteristics by using a heat welding method under the following conditions by a light welding method.
1, 73 were respectively formed. That is, the condition is (output of the electromagnetic heating mechanism) = 1200 W (heating time) = 1 minute (length of the welding mold 40) = 50 mm. However, the welding mold 40 by the electromagnetic heating mechanism 51 is used.
Is a local heating, and the central part of the welding mold 40 is 10 mm
To 210.degree. Then, the characteristics of the star coupler 70 were evaluated using the same optical power measurement system as described above. That is, the wavelength 660n
LED light (light intensity P ₁ = 39.0 μW) is input to the first channel CH ₁ of the star coupler 70, while output values P ₅ to CH _{5 to} CH ₈ to CH ₈ are output.
The P ₈ was measured, respectively. As a result, the output value P ₅ to P ₈
Are 0.062 μW, 0.059 μW, 0.054 μW, 0.05
5 μW, and the distribution ratio was 1.1: 1.1: 1.0: 1.0. The excess loss LS in this case is:

[0055]

(Equation 2)

Was

Next, the characteristics of the 2 ³ × 2 ³ channels of the star coupler 80 will be described.

The inventor of the present application formed each light branch portion by ultrasonic welding under the same conditions as above for the purpose of verifying the characteristics.

Then, the characteristics of the star coupler 80 were evaluated in the same manner as described above, using the same optical power measurement system as described above. That is, LED light having a wavelength of 660 nm (light intensity P
₁ = 15.5 μW) is input to the first channel CH ₁ (FIG. 12) of the star coupler 80, while the fiber ends 82a, 84a, 86 facing the first channel CH ₁ are input.
a, 88a, 82b, 84b, 86b, the output value P ₉ to P ₁₆ from 88b were measured. As a result, the output values P _{9 to} P ₁₆ are 1.32 μW, 1.33 μW, 1.28 μW,
1.30 μW, 1.20 μW, 1.35 μW, 1.30 μW, and 1.50 μW. The excess loss LS in this case is:

[0060]

(Equation 3)

Was

Next, the characteristics of the 2 ⁴ × 2 ^4-channel star coupler 90 will be described.

The inventor of the present application formed each light branch portion by ultrasonic welding under the same conditions as above for the purpose of verifying the characteristics.

Then, the characteristics of the star coupler 90 were evaluated using the same optical power measurement system as described above. That is, LED light having a wavelength of 660 nm (light intensity P
₁ = 15.5 μW) to the first channel CH ₁ (FIG. 15) of the star coupler 90, and the fiber ends 92a to 99a and 92b facing the first channel CH _1.
The output value P ₁₇ to P ₃₂ from ~99b were measured.
As a result, the output values P _{17 to} P ₃₂ are 0.68 μW and 0.55 μW, respectively.
μW, 0.52μW, 0.61μW, 0.60μW, 0.56μW, 0.49
μW, 0.55μW, 0.48μW, 0.61μW, 0.59μW, 0.58
μW, 0.55 μW, 0.60 μW, 0.60 μW, and 0.52 μW. The excess loss LS in this case is:

[0065]

(Equation 4)

Was as follows.

E. Effects of Embodiment As described above, according to the above embodiment, since the star coupler is constituted only by the plastic fiber, the coefficient of thermal expansion in each part of the star coupler is uniform. Therefore, even if the temperature of the usage environment of the star coupler changes,
Each part expands (or contracts) at the same rate. As a result, the characteristic change of the star coupler due to the temperature change is reduced. Further, since the optical branching portions of the star coupler are all ultrasonically or thermally welded, a sufficient strength can be obtained at the optical branching portions.

Further, as can be seen from the verification results of the above specific examples, all actually manufactured star couplers have low loss. In particular, in a star coupler manufactured by the ultrasonic welding method, the light loss is smaller than that in the case of heat welding. In addition, the distribution ratio of the star coupler can be set arbitrarily.

F. Modification Example of Ultrasonic Welding Type As shown in FIG. 2, the welding die 40 is configured to abut and hold an intermediate portion between _two plastic fibers F ₁ and F ₂ in a fitted state. Therefore, in order to form the light branching portion as described above, it is necessary to perform the ultrasonic welding process using the welding mold 40 for each light branching portion. For example, in order to manufacture the star coupler 70 (FIG. 9), four light branch portions 11a, 11b, 7
1, 73 need to be formed, and as a result, the ultrasonic welding process also needs to be performed four times. Therefore, there is a problem that the manufacturing operation of the star coupler becomes complicated.

Further, the star coupler manufactured by using the welding mold 40 has a problem that the length increases in the longitudinal direction X. For example, when the star coupler 70 is manufactured by the ultrasonic welding method as described above, the length L ₀ of the region occupying the light branching portion (the portion surrounded by the dotted line in FIG. 17) is 80 mm.
It will also be.

Therefore, the inventor of the present application has invented an ultrasonic welding type capable of manufacturing the above-described star coupler without causing the above-mentioned problems. Hereinafter, the structure of the ultrasonic welding type according to the present invention and 2 ² ×
The procedure in the case of producing a 2 ² channel star coupler will be described.

<Structure of Ultrasonic Welding Type> FIG. 18 is a perspective view showing an improved example of the ultrasonic welding type.
As shown in the figure, the ultrasonic welding mold 40 'includes first and second welding mold members 45 and 46 made of metal or resin.
And a frame member 47 finished so as to be freely fitted to the first and second welding-type members 45 and 46, respectively. For this reason, when the frame member 47 is fitted to the first welding member 45 and the second welding member 46 is fitted to the fitting body, the first and second welding members 45 and 46 are fitted.
Are integrated. The first and second welding members 4
The first and second welding members 45 and 46 may be integrated with each other so that the first and second welding members 5 and 46 can be fitted to each other. In this case, the frame member 47 becomes unnecessary.

On the upper surface of the first welding type member 45, two projections 45a and 45b are provided so as to protrude at a predetermined interval. That is, the two convex portions 45 sandwich the concave portion 45c.
a and 45b are arranged facing each other. And this convex part 4
5a is provided with two grooves 48a and 48b. The groove 48a is relatively deep, and is finished so that about two plastic fibers can be fitted therein. On the other hand, the groove 48b is relatively shallow, and is finished so that one plastic fiber can be freely engaged. Also, the convex portion 45b has
A relatively deep groove 48c is provided on the extension of the groove 48a similarly to the groove 48a, and a groove 48b is provided on the extension of the groove 48b.
Similarly, a relatively shallow groove 48d is provided.

FIG. 19 is a view showing the second welding-type member 46, and is a perspective view of the second welding-type member 46 of FIG. 18 viewed from another angle. As can be seen from FIGS. 18 and 19, the second welded member 46 is finished similarly to the first welded member 45. That is, the second welding type member 4
6, two convex portions 46a and 46b are provided so as to protrude across the concave portion 46c, relatively shallow groove portions 48e and 48g are provided in the convex portions 46a and 46b, respectively, and relatively deep groove portions 48f and 48h are provided respectively. Convex portions 46a, 46b
It is provided in. Therefore, as described later, after appropriately arranging the four plastic fibers and integrating the first and second welding members 45 and 46 as described above, the grooves 48a and 48e, the grooves 48b and 48f,
The two plastic fibers are held in contact with the grooves 48c and 48g and the grooves 48d and 48h, respectively, over a predetermined length (FIG. 20). In FIG. 20, the illustration of the frame member 47 is omitted for convenience of the drawing.

<Manufacturing Procedure of Star Coupler 70> Next, a manufacturing procedure in the case of manufacturing a 2 ² × 2 ^2- channel star coupler 70 using the ultrasonic welding mold 40 ′ will be described with reference to FIGS. 21 to 23. I do. First, the first
The frame member 47 is fitted to the welding type member 45. The illustration of the frame member 47 is omitted to facilitate understanding of the manufacturing procedure.

The first of the plastic fibers F ₂
And the second intermediate portions P ₂₁ and P ₂₂ are fitted into the grooves 48 a and 48 c of the first welding member 45, respectively, and the first and second intermediate portions P ₃₁ and P ₃₁ of the plastic fiber F ₃ are fitted.
₃₂ is engaged with the grooves 48f, 48h of the second welding member 46 (FIG. 21).

[0077] Further, as shown in FIG. 22, while the curving deformation of the central portion of the plastic fiber F _4, to engage the first intermediate portion P ₄₁ that the groove 48b of the first welding mold member 45, the the second middle P ₄₂ are fitted into the groove portion 48c is brought into contact with the second intermediate portion P ₂₂ of the plastic fiber F _2.

Further, as shown in FIG. 23, the _first portion of the plastic fiber F ₁ is bent while being deformed.
While it is brought into contact with the first intermediate portion P ₂₁ of the plastic fiber F ₂ the intermediate portion P ₁₁ are fitted into the groove 48a of the first welding mold member 45, a second intermediate portion P ₁₂ is engaged with the groove portion 48d.

Subsequently, the first and second welding members 45 and 46 are integrated as described above. As a result, the groove 48a, the first intermediate portion P _11, P ₂₁ of the plastic fibers F _1, F ₂ are in contact held by 48e.
Similarly, the first intermediate portions P ₃₁ and P ₄₁ of the plastic fibers F ₃ and F ₄ are formed by the grooves 48 b and 48 f.
8c, 48g, plastic fibers F ₂ , F ₄
The second intermediate portions P ₂₂ and P ₄₂ of the plastic fibers F ₁ and F ₃ are formed by the grooves 48 d and 48 h.
_12, P ₃₂ are abutting respectively held.

As described above, when the plastic fibers F _{1 to} F ₄ are held in contact with each other at predetermined positions, FIG.
Ultrasonic welding process by the ultrasonic welding apparatus 60 is performed in, ² 2 × 2 2-channel star coupler 70 (FIG. 17)
Is formed. Since the details of the ultrasonic welding process have already been described above, the description thereof is omitted here.

[0081] As described above, simplification of the case where a welding-type 40 ', by a single ultrasonic welding process can produce a 2 ² × 2 ^2-channel star coupler 70, star coupler manufacturing operations Can be achieved.

Next, the characteristics of the star coupler 70 made of an uncrosslinked polymethyl methacrylate plastic fiber manufactured by using the ultrasonic welding type 40 'will be verified.

The inventor of the present application manufactured the star coupler 70 under the following conditions using the above-described ultrasonic welding method. That is, the condition is (pressing force) = 15 kgf (vibration frequency) = 15 kHz (vibration amplitude) = 40 μm (vibration application time) = 1.0 second. The dimensions of the ultrasonic welding mold 40 'were set as follows. That is, the dimensions are (length L ₁ of convex portions 45a, 46a) = 20 mm (length L ₂ of convex portions 45b, 46b) = 20 mm (interval L ₃ between both convex portions) = 5 mm.

The characteristics of the star coupler 70 were evaluated in the same manner as described above, using the same optical power measurement system as described above. That is, LED light having a wavelength of 660 nm (light intensity P
₁ = 15.4MyuW a), while the input to the first channel CH ₁ of the star coupler 70, the output value P ₅ to P ₈ from the fifth to eighth channels CH ₅ to CH ₈ opposite to the first channel CH ₁ Each was measured. As a result, the output value P
₅ to P ₈ are respectively 2.8 μW, 2.5 μW, 4.1 μW , 2.
7 μW, and the distribution ratio was 1.1: 1.0: 1.6: 1.1. The excess loss LS in this case is:

[0085]

(Equation 5)

Was as follows.

As can be seen from the above verification results, the star coupler manufactured by using the ultrasonic welding type 40 'has low loss as in the above-described specific example. In addition, the length L ₀ of the region occupying the light branching portion (the portion surrounded by the dotted line in FIG. 17) is 45 mm, and the specific example (L ₀ = 80 m)
m) is shorter.

[0088]

As described above, according to the first and second aspects of the present invention, the optical coupler is formed by mutual welding of the intermediate portions of the plastic fibers to form the star coupler, so that the star coupler is formed. Sufficient strength is obtained. Moreover,
The component parts of the star coupler are only plastic fibers, so that a change in the characteristics of the star coupler due to a change in temperature can be prevented. That is, according to the first and second aspects of the present invention, a star coupler having a moderate use environment condition and high versatility can be obtained.

According to the third aspect of the present invention, when the first and second welding members are integrated, the first to fourth welding members are formed.
The first and second intermediate portions of the plastic fiber are appropriately abutted with each other. Therefore, when the ultrasonic vibration is applied to at least one of the first and second welding-type members, the ultrasonic vibration is transmitted to each contact portion, and the first to fourth plastic fibers are moved. At the same time, they are mutually welded to produce a star coupler.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a procedure for manufacturing an optical element.

FIG. 2 is a sectional view showing one embodiment of a welding type used for manufacturing an optical element and a star coupler.

FIG. 3 is a configuration diagram showing a configuration of a heat welding apparatus.

FIG. 4 is a configuration diagram showing a configuration of an ultrasonic welding device.

FIG. 5 is a schematic view showing a procedure for manufacturing an optical element.

FIG. 6 is a schematic view of an optical element manufactured by the procedure shown in FIG.

FIG. 7 is a schematic diagram for explaining a first embodiment of the star coupler according to the present invention.

FIG. 8 is a schematic diagram for explaining a first embodiment of the star coupler according to the present invention.

FIG. 9 is a schematic diagram for explaining a first embodiment of the star coupler according to the present invention.

FIG. 10 is a schematic diagram for explaining a second embodiment of the star coupler according to the present invention.

FIG. 11 is a schematic diagram for explaining a second embodiment of the star coupler according to the present invention.

FIG. 12 is a schematic diagram for explaining a second embodiment of the star coupler according to the present invention.

FIG. 13 is a schematic diagram for explaining a third embodiment of the star coupler according to the present invention.

FIG. 14 is a schematic diagram for explaining a third embodiment of the star coupler according to the present invention.

FIG. 15 is a schematic diagram for explaining a third embodiment of the star coupler according to the present invention.

FIG. 16 is a schematic diagram for explaining another embodiment of the star coupler according to the present invention.

FIG. 17 is a schematic diagram showing a 2 ² × 2 ² channel star coupler.

FIG. 18 is a perspective view showing an improved example of the ultrasonic welding type.

FIG. 19 is a view showing a second welding type member.

FIG. 20 is a front view of the ultrasonic welding type.

FIG. 21 is a view for explaining a manufacturing procedure in the case of manufacturing a star coupler using the ultrasonic welding type shown in FIG. 18;

FIG. 22 is a diagram for explaining a manufacturing procedure in the case of manufacturing a star coupler using the ultrasonic welding type in FIG. 18;

FIG. 23 is a view for explaining a manufacturing procedure in the case of manufacturing a star coupler using the ultrasonic welding type shown in FIG. 18;

FIG. 24 is a schematic diagram showing an example of a star communication network as a background art of the present invention.

FIG. 25 is a diagram showing a conventional star coupler.

[Explanation of symbols]

10, 10a, 10b Optical elements 11, 11a, 11b, 71, 73, 81, 83, 85, 87, 91a to 91h Optical branching / coupling portions 12a, 12b, 13a, 13b, 72a, 72b, 74a, 74b, 82a, 82b, 84a, 84b, 86a, 86b, 88a, 88b, 91a to 99a, 91b to 99b Fiber end part 45 First welding member 45a, 45b, 46a, 46b Convex part 45c, 46c Concave part 46 Second weld type member 48a~48h groove F ₁ to F ₄ plus tick fiber _{P 11, P 21, P 31} , P 41 first intermediate portion _{P 12, P 22, P 32} , P 42 the second intermediate portion

Claims (3)

(57) [Claims] An optical branch portion formed by welding intermediate portions of two plastic fibers to each other; first and second input fiber ends extending from one ends of the optical branch portion; and the optical branch portion. A ² × 2 ^2- channel star coupler configured by combining two optical elements having first and second output fiber ends extending from the other end of the first output fiber end; The middle parts are welded together
Optical splitter is formed Te Rutotomoni, the second intermediate portion is welded to one another optical splitter output fiber ends form
A star coupler characterized by being formed . Wherein the input fiber ends 2 ⁿ present which functions as an input channel ^{(n ≧ 2), 2 n} × and an output fiber ends 2 ⁿ present which functions as an output channel 2
The ^n-channel star coupler a two combination 2 ^{n + 1} × constituted by 2 ^{n + 1} channel star coupler, second intermediate portion of the output fiber ends of one of the 2 ⁿ × 2 ^n-channel star coupler and the other A star coupler characterized in that it is fused to each other to form an optical branching portion while being in one-to-one correspondence with an intermediate portion of an output fiber end of an ⁿ × 2 ^n- channel star coupler. . 3. The first and second fusion bonding members are made of first and second welded members, and the first intermediate portions of the first and second plastic fibers are integrated with each other, and the third and third plastic fibers are integrated with each other. 4 and the second intermediate portion of the first and third plastic fibers.
While the intermediate portions and the second intermediate portions of the second and fourth plastic fibers are held in contact with each other, at least one of the first and second welding-type members is applied to the superconducting member. An ultrasonic welding type for transmitting ultrasonic vibration to each contact portion and ultrasonically welding the first to fourth plastic fibers to each other, wherein the first welding type member faces each other with a concave portion interposed therebetween. A first groove portion having a pair of convex portions arranged, and a first groove portion in which the first intermediate portion of the second and the first plastic fibers is finished so as to be freely fitted in this order in one convex portion; The second intermediate portion of the second and fourth plastic fibers is provided in this order on the other convex portion while the second intermediate portion of the second and fourth plastic fibers is finished so as to be engageable with the first intermediate portion of the plastic fiber of No. 4. Third groove finished to fit freely And a fourth groove formed so as to be freely engageable with the second intermediate portion of the first plastic fiber, and the second welding member is provided with a pair of convex portions opposed to each other with a concave portion interposed therebetween. A fifth groove formed on one of the protrusions so as to be engageable with the first intermediate portion of the first plastic fiber, and the first intermediate portion of the third and fourth plastic fibers. A sixth groove finished so as to be freely fitted in this order, and a seventh groove finished so as to be freely engageable with the second intermediate portion of the fourth plastic fiber on the other convex portion; An ultrasonic welding type, wherein an eighth groove is provided in which the second intermediate portion of the third and first plastic fibers is fitted so as to be freely inserted in this order.