JPH07294742A - Optical transmission material - Google Patents

Abstract

PURPOSE:To maintain the attenuation rate of light by multilayered films at a specified rate by providing an optical fiber with an even number of sheets of multilayered films in parallel with a plane slightly inclined from a plane perpendicular to the optical axis of this fiber in its mid-way and specifying the arrangement thereof. CONSTITUTION:The multilayered films 3, 10 of the same kind are arranged in a pair in parallel with the plane slightly inclined from the plane 4 perpendicular to the optical axis (a) in the mid-way of the light transmission path in the optical fiber 1 of one ferrule 2 embedded with the optical fiber 1 at its center by rotating these films at about 90 deg. with each other around the optical axis(a). In such a case, the multilayered films 3 of which the rotating direction is rotated counterclockwise are the multilayered films 10. The multilayered films 3 and the multilayered films 10 do not attain the state parallel with each other. The attenuation rates of the X direction and Y direction of the plane perpendicular to the optical axis (a) of the optical fiber 1 are complementarily attenuated with each other and are made constant even if there is a case that the plane of polarization of the incident light on the optical fiber 1 is rotated around the optical axis a by an external factor, according to such light transmission member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable for optical communication having an optical fiber used for optical communication, in order to give a desired attenuation or to pass a light of a desired wavelength limitedly. The present invention relates to an optical transmission member using a multilayer film on the way.

[0002]

2. Description of the Related Art Conventionally, an optical attenuator for attenuating a high power light amount to a predetermined amount so as to obtain an appropriate light reception level is provided in the middle of an optical fiber line used for an optical communication cable, When a filter for limiting the passage of light of a desired wavelength is provided, the filter shown in FIG.
As shown in (a) and (b), the multilayer film 3 was interposed in the longitudinal direction of the ferrule 2 with the optical fiber 1 embedded in the center.

The multi-layer film 3 is used as a means for eliminating the disadvantage that the attenuation amount changes due to the oxidation due to the increase of the light input level when the conventional metal film is used.

The multilayer film 3 is formed by the optical axis a of the optical fiber 1.
The light is prevented from being reflected by tilting it slightly (for example, about 8 °) from the orthogonal surface without arranging it on the orthogonal surface orthogonal to.

[0005]

However, in the arrangement structure of the multilayer film 3 as described above, as shown in FIG.
There is a problem in that the transmitted light has a different attenuation amount depending on the arrangement relationship of the multilayer film 3 in the XY plane 4, resulting in polarization dependence.

That is, when the incident light 6 having the polarization plane 5 as shown passes through the multilayer film 3 which is interposed in the transmission optical path and is inclined with respect to the XY plane 4, the x component of the incident light 6 is obtained. And y
When the amount of attenuation is compared with that of the component, the output light 7
The attenuation rates of the x component and the y component of are different.

Therefore, as shown in FIGS. 18 (a) and 18 (b), when the polarization plane 5 of the incident light 6 is in the X-axis direction, assuming that the attenuation factor of the multilayer film 3 in the X-direction is αx, the incident light is incident. When the incident light power of the light 6 is P6x, the outgoing light power P7x of the outgoing light 7 is P7x = αx · P6x. On the other hand, when the polarization plane 5 of the incident light 6 is in the Y-axis direction and the attenuation factor of the multilayer film 3 in the Y direction is αy, the output light power P7y = αy · P6y of the output light 7 is obtained as described above. Becomes

Since αx ≠ αy, even if P6x = P6y, the output light powers P7x and P7y in the X and Y directions of the output light 7 are different from each other, and the polarization plane 5 of the input light 6 is obtained. Depending on the direction, the attenuation rate will be different from the predetermined one.

When the optical fiber 1 is touched by the hand or the temperature is affected by the outside air temperature, the polarization plane of the light rotates, and the optical fiber 1 is tilted with respect to the XY plane 4 and set in the ferrule. Since the attenuation factors of the x component and the y component of the multilayer film are different, the attenuation factor of the multilayer film 3 is apparently changed, and the light receiving level of the emitted light 7 is changed.

As described above, in the optical transmission member using the conventional multilayer film, the apparent attenuation rate changes due to the polarization plane of incident light, temperature change, etc., and it cannot be maintained at a predetermined attenuation rate. There was a problem, and there was a problem to be solved here.

The present invention has been made in view of the above problems, and provides an optical transmission member in which a constant attenuation rate is maintained without being affected by external factors. With the goal.

[0012]

The gist of the present invention for solving the above problems and achieving the above objects is to provide a slight inclination from the plane perpendicular to the optical axis of the optical fiber in the middle of the optical transmission line in the optical fiber. Parallel to the plane, and at least two or more even-numbered multilayer films are provided, half of the multilayer films are arranged at the same rotation angle about the optical axis, and the remaining half of the multilayer films are That is, half of the multilayer films are arranged so as to be rotated by about 90 ° about the optical axis.

Further, a multilayer film provided in the middle of the optical transmission line in the optical fiber in parallel with a plane slightly inclined from the plane perpendicular to the optical axis of the optical fiber is rotated about 90 ° with respect to the optical axis. That is, a required number of them are arranged in pairs.

Half of the multilayer films are arranged at the same rotation angle about the optical axis, and the other half of the multilayer films rotate about the optical axis by about 90 ° with respect to the half multilayer films. At least two or more even-numbered multilayer films are provided for each ferrule in which the optical fiber is embedded; and half of the multilayer films are arranged at the same rotation angle about the optical axis. , The remaining half of the multilayer films are arranged by rotating the optical axis about 90 ° with respect to the half of the multilayer films, and at least two or more even-numbered multilayer films are provided.
One ferrule with embedded optical fibers, one for each ferrule, was arranged in series; to prevent multiple reflections, both sides of the substrate provided with the multilayer film were not parallel to each other; In order to adjust the cut-off wavelength of the film, the slit width of the ferrule is expanded more than the thickness of the substrate provided with the multilayer film so that the inclination of the multilayer film embedded in the slit can be adjusted. is there.

[0015]

According to the optical transmission member of the present invention, even if the polarization plane of the light incident on the optical fiber is rotated about the optical axis due to an external factor, the optical axis of the optical fiber is changed. The multi-layered films rotated about 90 ° with respect to each other in pairs form a complementary attenuation of the attenuation rates in the X-direction and the Y-direction of the surface orthogonal to the optical axis of the optical fiber, so that the attenuation rate becomes constant.

Further, by arranging the multilayer film for each ferrule or connecting the ferrules, it becomes possible to easily adjust to obtain a predetermined attenuation amount.

Further, since the both surfaces of the substrate provided with the multilayer film are not parallel to each other, multiple reflection is prevented and a desired attenuation amount can be obtained.

Since the slit width of the ferrule is made wider than the plate thickness of the substrate having the multilayer film, the cutoff wavelength of the multilayer film can be easily adjusted.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 show a front view and a plan view of a first embodiment according to the present invention. For ease of understanding, the portions corresponding to those in the conventional example will be described with the same reference numerals.

In the first embodiment, in one ferrule 2 having the optical fiber 1 embedded in the center, it is slightly inclined from the plane 4 perpendicular to the optical axis a in the middle of the optical transmission line in the optical fiber 1 ( For example, the multilayer films 3 and 10 of the same type provided in a plane of 8 ° are paired by rotating each other about 90 ° about the optical axis a of the optical fiber 1. in this case,
Regarding the rotation direction, the multilayer film 10 is in a state in which the multilayer film 3 is rotated counterclockwise as viewed from the left side of the drawing. Therefore, the multilayer film 3 and the multilayer film 10 are not in a parallel state.

To form such a ferrule 2,
The ferrule 2 is cut at two positions in a plane slightly tilted from a plane 4 perpendicular to the optical axis a and in a positional relationship in which the optical fiber 1 is rotated about 90 ° with respect to the optical axis a. The multilayer films 3 and 10 are fixed to each other with an adhesive or the like. The separation distance between the multilayer films 3 and 10 is set arbitrarily.

The second embodiment shown in FIGS. 3 to 4 is
It is a modification of the first embodiment, and is the same kind of multilayer film 3,
The slit 1 provided on the ferrule 2 so as to cut the optical axis a by slightly tilting the optical axis 10 from the plane 4 perpendicular to the optical axis a.
It is fixed to 1 and 12 with an adhesive or the like. Of course, the slits 11 and 12 are approximately 9 with respect to the optical axis a.
The layout is such that it is rotated by 0 °.

Ferrule 2 formed in this way
Is used as a fixed optical attenuator or as a filter for passing light of a specific wavelength, for example, when an incident light 6 such as a laser enters from the left side of the drawings in FIGS. It is attenuated at a constant attenuation rate without being affected by physical factors. Hereinafter, it will be described that the attenuation rate is constant.

That is, to explain in detail with reference to FIG.
The multilayer film 3 is inclined with respect to the XY plane 4 orthogonal to the Z axis of the optical axis a by θ1 rotation about the X axis. Further, the multilayer film 10 is arranged such that the multilayer film 3 is rotated by 90 ° in the light propagation direction, that is, in the clockwise direction when viewed from the incident light 6 side, with the Z axis as the center of rotation. Therefore, the multilayer film 10 is arranged at an angle of θ2 (= θ1) about the Y axis with respect to the XY plane 4 at the position of the multilayer film 10. Therefore, the multilayer film 3 and the multilayer film 10 are not in a parallel state.

The attenuation factor of the multilayer film 3 in the X-axis direction is α
If x is the attenuation factor in the Y-axis direction, αy is the attenuation factor in the multilayer film 10 rotated about 90 ° about the Z-axis, and the attenuation factor in the X-axis direction is αy.
The attenuation factor in the axial direction is αx.

Therefore, when the incident light power P of the incident light 6 is divided into the x component and the y component and the attenuation amount is obtained as Px and Py, first, in the light passing through the multilayer film 3, Px1 = αx · P
x, Py1 = αy · Py, and the light is multilayer film 1
By passing 0, Px2 of the x component and Py2 of the y component of the output light power of the output light 7 are Px2 = αy · Px1 = αy
・ (Αx ・ Px) = (αy ・ αx) ・ Px, Py2 = α
x · Py1 = αx · (αy · Py) = (αx · αy) ·
Py, and the attenuation rate of both the x component and the y component becomes (αx · αy).

In this way, the paired multilayer films 3 and 10 are formed.
However, since the polarization plane 5 of the incident light 6 is rotated and changed by an external factor, the multi-layer film 3 is rotated about 90 degrees about the Z axis which is the optical axis a. At 10, the optical transmission member has an apparent attenuation factor that does not change.

Further, since the multilayer films 3 and 10 have a relationship of being rotated by about 90 ° about the Z axis which is the optical axis a, as shown in FIG. Even if the multilayer film 3 is rotated counterclockwise from the viewpoint to arrange the multilayer film 10, the attenuation rate becomes (αx · αy), which is the same as the arrangement relationship of the multilayer films 3 and 10 shown in FIG. The decay rate. Further, the attenuation rate does not change even when the incident light 6 and the emitted light 7 are set in opposite light propagation directions and are optically transmitted from the multilayer film 10 to the multilayer film 3.

Thus, the optical axis a is attached to one ferrule 2.
By providing the multi-layered films 3 and 10 in a positional relationship that are rotated by about 90 ° with respect to each other as a rotation center, the attenuation factor in the emitted light does not change even if the polarization plane of the light changes The optical transmission member of is obtained.

The third embodiment according to the present invention is shown in FIGS.
As shown in FIG. 1, the multilayer films 3 and 10 that are rotated about the optical axis a of the optical fiber 1 by about 90 ° and form a pair are provided in the ferrules 2 and 2a in which the optical fiber 1 is embedded. It is a pair in which those provided with 3 and 10 are connected by an adhesive.

Also in this case, the multilayer film 10 may be rotated about the optical axis a with respect to the multilayer film 3 by approximately 90 ° in either the clockwise direction or the counterclockwise direction.

The fourth embodiment according to the present invention is shown in FIGS.
As shown in 0, it is a modification of the above-mentioned third embodiment,
The slits 13 and 14 are provided in the ferrules 2 and 2a, the multilayer films 3 and 10 are fitted in this, and are fixed by the adhesive agent.

As described above, in the third embodiment and the fourth embodiment, it is possible to save the troublesome work of fixing the multilayer films 3 and 10 by cutting one ferrule 2 at two positions and in a positional relationship rotated by 90 °. As a result, the number of man-hours for manufacturing the optical transmission member is reduced, and the cost is reduced.

In each of the above embodiments, two multilayer films 3 and 10 have been described. However, even if two or more even films are used, the same constant attenuation factor can be obtained. As a fifth embodiment, as shown in FIGS. 11 to 12, four multi-layer films 3, 10, 15, 16 are provided for each ferrule 2 or one ferrule 2 is used.
It is also possible to provide a multi-layer film one by one and connect them to connect them.

That is, in the fifth embodiment, the multilayer film 3 and the multilayer film 10 are rotated by about 90 ° about the optical axis a, and the multilayer film 15 and the multilayer film 16 are further rotated by about 90 °. ° It has a rotated relationship.

The multilayer film 3 and the multilayer film 15 have the same rotation angle about the optical axis a. The arrangement of the four multilayer films 3, 10, 15, 16 is as shown in FIG.
Not limited to the arrangement example shown in FIG. 1, for example, the multilayer film 10 may be interposed between the multilayer films 15 and 16 from the arrangement state of FIG. 11, or may be arranged further to the right side of the multilayer film 16 than the drawing. Good. Alternatively, the multilayer film 15 may be arranged on the left side of the multilayer film 3 in the figure.

Further, as a sixth embodiment, as shown in FIG. 12, two multilayer films which are in a relationship of being rotated by approximately 90 ° with each other and two multilayer films which are in a relationship of being rotated by approximately 90 ° with each other. And may have a positional relationship in which they are rotated at a slight rotation angle about the optical axis a.

That is, the multilayer films 3 and 10 are in a relationship of being rotated by approximately 90 ° to each other, and the multilayer films 15 and 16 are approximately 90 °.
In a rotated relationship, and said multilayer film 3 and multilayer film 1
0 may be a positional relationship of rotating about the optical axis a, and is not limited to the position of the same rotation angle about the optical axis a.

Then, the multi-layered films 3, 10, 15, 16
However, it may be provided for each ferrule 2 as described above, or one multi-layer film may be provided for one ferrule 2 so as to be connected to each other.

Next, a seventh embodiment will be described with reference to the multilayer films 3 and 10 described above.
Alternatively, in the arrangement of the multilayer films 15 and 16, as shown in FIG. 13, it is formed by vapor deposition on both surfaces of the glass substrate 17, and both surfaces of the substrate 17 on which the multilayer films 3 and 10 (15, 16) are vapor deposited. Is not parallel but tilted by the angle θ.

By using such a substrate structure, the substrate 1
When multiple reflections between 7 are prevented and the attenuation amount is α for each multilayer film, the total attenuation amount when a plurality of multilayer films is arranged is a desired attenuation amount (for example, α + α = 2α). Will be obtained.

Next, as an eighth embodiment, a means for adjusting the multilayer film installed in the slit of the ferrule 2 will be described. The attempt to adjust this multilayer film in the slit is
When the optical transmission member according to the present invention is used as an optical filter (for example, a bandpass filter), the cutoff wavelength changes depending on the inclination of the multilayer film, so that the cutoff wavelength is adjusted to a desired cutoff wavelength in advance. Is.

Therefore, as shown in FIG. 14, for example, the width 11a of the slit 11 of the ferrule 2 is made of glass provided with the multilayer film 3 so that the inclination of the multilayer film 3 contained in the slit can be adjusted. It is expanded from the plate thickness of the substrate 17.
However, the width 11a of the slit 11 is not so wide that the multilayer film 3 of the substrate 17 is perpendicular to the optical axis a.

Then, as shown in FIG. 15, after the adhesives 11b and 12a are injected into the slits 11 and 12 of the ferrule 2 in a required amount, the tip portion of the substrate 17a is inserted into the slits 11 and the slits 11 and 12 of the substrate 17a are inserted. The rear end portion projects from the surface of the ferrule 2 and is held by the vapor deposition plate holder 18.

Next, the measurement light is made incident on the ferrule 2 from the light source 19, and the wavelength characteristic of the light emitted from the ferrule 2 is measured by the optical spectrum analyzer 20.
Then, the inclination of the substrate 17a is adjusted by the vapor deposition plate holder 18 to a desired cutoff wavelength, and the adhesive 11a is cured with a curing agent to maintain the state of the substrate 17a.

Further, the portion of the substrate 17a protruding from the surface of the ferrule 2 is cut. In the other slit 12 as well, the substrate 17 is fixed in the same manner by adjusting its inclination.

In this way, for example, if one multilayer film is a high-pass filter and the other multilayer film is a low-pass filter, the cutoff wavelength of each multilayer film is adjusted to a desired value, so that the bandpass filter bandwidth is adjusted. It is possible to obtain narrow ones.

As described above, at least two even-numbered multilayer films are arranged in the optical transmission member so that one half and the other half are rotated by about 90 ° with respect to the optical axis a thereof. Even if the plane of polarization of the incident light changes around the optical axis due to an external factor, the attenuation factor can be maintained constant, and a polarization-independent optical transmission member can be obtained.

[0049]

As described above, the optical transmission member of the present invention is provided at least in the middle of the optical transmission path of the optical fiber so as to be parallel to a plane slightly inclined from the plane perpendicular to the optical axis of the optical fiber. Two or more even-numbered multilayer films are provided, and half of the multilayer films are arranged at the same rotation angle about the optical axis, and the remaining half of the multilayer films are the half of the multilayer films. Since they are arranged so as to rotate about 90 ° about the optical axis, the attenuation factors of the x component and the y component of the multilayer film act in a complementary manner to make the attenuation factor of the outgoing light constant, and the polarization plane of the incident light. Even if an external factor such as heat is applied to the direction of the optical fiber or to the optical fiber, a polarization-independent optical transmission member whose attenuation factor does not change can be obtained, which is an excellent effect.

A multilayer film provided in the middle of the optical transmission line in the optical fiber in parallel with a plane slightly inclined from the plane perpendicular to the optical axis of the optical fiber is rotated about 90 ° about the optical axis and rotated in pairs. Since the required number is provided, the attenuation factors of the x-component and the y-component of the multilayer film act in a complementary manner by the paired multilayer film to make the attenuation factor of the outgoing light constant, and Even if an external factor such as heat is applied to the direction or the optical fiber, a polarization-independent optical transmission member whose attenuation factor does not change can be obtained, which is an excellent effect.

Half of the multilayer films are arranged at the same rotation angle about the optical axis, and the other half of the multilayer films are rotated by about 90 ° about the optical axis with respect to the half of the multilayer films. Since at least two or more even-numbered multilayer films arranged are provided for each ferrule in which the optical fiber is embedded,
Various ferrules having a constant attenuation rate are prepared and can be arbitrarily selected and used as a filter, a fixed optical attenuator or the like, which has an excellent effect of improving work efficiency.

Half of the multilayer films are arranged at the same rotation angle about the optical axis, and the other half of the multilayer films are rotated by about 90 ° about the optical axis with respect to the half multilayer films. Since at least two or more even-numbered multi-layered films arranged, one for each ferrule in which the optical fiber is embedded, are arranged in series, one multi-layered film is provided for each ferrule. When the provided one can be installed in the middle of the transmission optical path by simply rotating it 90 ° and fixing it, work becomes easier, and one ferrule is cut at two positions and rotated 90 ° to fix the multilayer film. It saves you the trouble of
This has an excellent effect that the man-hours for manufacturing the optical transmission member can be reduced and the cost can be reduced easily.

Since both surfaces of the substrate provided with the multilayer film are not parallel to each other, multiple reflection between the substrates is prevented,
It has an excellent effect that a desired amount of attenuation is obtained and reliability is improved.

Since the slit width of the ferrule is expanded more than the plate thickness of the substrate provided with the multilayer film so that the inclination of the multilayer film embedded in the slit can be adjusted, the desired cutoff wavelength should be set. This makes it possible to achieve a superior effect that the bandwidth of the bandpass filter can be narrowed with high accuracy.

[Brief description of drawings]

FIG. 1 is a front view of a first embodiment according to the present invention.

FIG. 2 is a plan view of the first embodiment.

FIG. 3 is a front view of a second embodiment according to the present invention.

FIG. 4 is a plan view of the second embodiment.

FIG. 5 is an explanatory diagram illustrating an attenuation rate of the optical transmission member according to the present invention.

FIG. 6 is an explanatory diagram showing another example in which the arrangement of the multilayer films in FIG. 5 is changed.

FIG. 7 is a front view of a third embodiment according to the present invention.

FIG. 8 is a plan view of the third embodiment.

FIG. 9 is a front view of a fourth embodiment according to the present invention.

FIG. 10 is a plan view of the fourth embodiment.

FIG. 11 is an explanatory diagram of the fifth embodiment.

FIG. 12 is an explanatory diagram of the sixth embodiment.

FIG. 13 is an explanatory diagram of the seventh embodiment.

FIG. 14 is an enlarged explanatory view of a portion of the eighth embodiment.

FIG. 15 is an explanatory diagram of the eighth embodiment.

FIG. 16 is a front view (a) and a plan view (b) of an optical transmission member according to a conventional example.

FIG. 17 is an explanatory diagram showing how the light is attenuated.

FIG. 18 shows a case where the plane of polarization of the light is in the X-axis direction (a).
FIG. 6 is an explanatory diagram showing how light is attenuated in the case of (B) in the Y-axis direction.

[Explanation of symbols]

 1 optical fiber, 2,2a ferrule, 3,10,15,16 multilayer film, 4 XY plane perpendicular to optical axis, 5 polarization plane of light, 6 incident light, 7 emitted light, 11, 12, 13, 14 slits, 17 substrate, 18 vapor deposition plate holder, 19 light source, 20 optical spectrum analyzer.

Front page continued (72) Inventor Kuniharu Kato 1-6, Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Kazunori Kanayama 1-1-6, Uchiyuki-cho, Chiyoda-ku, Tokyo Phone Co., Ltd.

Claims (6)

[Claims] 1. An optical fiber in an optical transmission path,
At least two or more even-numbered multilayer films are provided parallel to a plane slightly inclined from the plane perpendicular to the optical axis of the optical fiber, and half of the multilayer films have the same rotation angle about the optical axis. And the remaining half of the multi-layered film is disposed by rotating the multi-layered film of about half with respect to the multi-layered film by about 90 ° about the optical axis. 2. In the middle of the optical transmission line in the optical fiber,
A plurality of multilayer films provided in parallel to a plane slightly inclined from a plane perpendicular to the optical axis of the optical fiber are rotated about the optical axis by about 90 ° and arranged in pairs so that a required number of layers are provided. Transmission member. 3. Half of the multilayer films are arranged at the same rotation angle about the optical axis, and the other half of the multilayer films rotate about the optical axis by about 90 ° with respect to the half multilayer films. At least two or more even-numbered multilayer films arranged by
The optical transmission member according to claim 1, wherein the optical transmission member is provided for each ferrule in which an optical fiber is embedded. 4. Half of the multilayer films are arranged at the same rotation angle about the optical axis, and the other half of the multilayer films rotate about the optical axis by about 90 ° with respect to the half multilayer films. At least two or more even-numbered multilayer films arranged by
2. A ferrule in which an optical fiber is embedded, one ferrule provided for each ferrule is connected and arranged.
The optical transmission member according to. 5. The optical transmission member according to claim 1, wherein both surfaces of the substrate having the multilayer film are not parallel to each other. 6. A ferrule having a slit width wider than a plate thickness of a substrate provided with the multilayer film so that the inclination of the multilayer film provided in the slit can be adjusted. 5. The optical transmission member according to any one of 5.