JPH06174963A - Optical branching and coupling element - Google Patents

Abstract

PURPOSE:To provide the optical branching and coupling element having high coupling efficiency of light by matching incident and exit angles of luminous fluxes and the numerical aperture of optical fibers with the optical branching and coupling element for optical communication which branches one light signal to N-pieces of the optical fibers and condenses the light signals from N-pieces of the optical fibers to one optical fiber. CONSTITUTION:A unit optical element 5a is constituted by arranging a first curved surface Sp1 having the end face of the fiber 11 at a focus O1 and a second curved surface Sp2 having the end face of the fiber 12a at a focus Oa2 in such a manner that the their light reflection surfaces face each other and by disposing the first curved surface Sp1 and the second curved surface Sp2 in such a manner that the luminous flux 8a on the on side from the center line of the fiber 11 among the diverging luminous fluxes determined by the exit numerical aperture of the exit end face of the fiber 11 is made incident on the incident end face of the fiber 12a at the incident angle corresponding to the incident numerical aperture. Plural pieces of such unit optical elements 5a are provided and plural pieces of these unit optical elements 5a commonly possess the first optical fiber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical branching / coupling element, and more particularly to a star coupler type optical branching / coupling element.

[0002]

2. Description of the Related Art In order to construct a local area network (hereinafter referred to as LAN) using optical communication, one optical signal is branched into N optical fibers or one optical signal from N optical fibers is divided into one optical signal. An element that collects in an optical fiber is required. An element shown in FIG. 5 is known as an element that achieves such an object.

The optical branch-coupling element shown in FIG.
It was disclosed in 11. FIG. 5 (a) shows the principle of this optical branching coupling, and an angle θ ₁ formed by a straight line connecting one focus O ₃ on the ellipse and one point P on the ellipse with the tangent at the intersection point P ₁
And the angle θ ₂ formed by the straight line connecting the other focus O ₄ and the intersection point P and the tangent line are equal to each other. That is, the property that the light emitted from the elliptical focus is focused on the other focus is used.

FIG. 5B shows a prior art optical branching / coupling device utilizing the above principle. One focus O ₁ of the ellipse forming the spheroid as a common, other focal point Oa _2, Ob _2, Oc ₂ to the optical fiber 12a, 12b, by arranging 12c, optical fiber 11 arranged in the focal point O ₁ The emitted optical signal is reflected by the spheroid and is evenly distributed to the optical fibers 12a, 12b, 12c.

[0005]

In such an optical branching / coupling device, the optical signal emitted from the optical fiber 11 is reflected by the spheroid and is incident on the optical fibers 12a, 12b, 12c depending on the emission angle of the light. In some cases, the incident angle at that time may be larger than the optical fiber incident limit angle. Also,
The light emitted from the optical fiber 11 diverges with an angular distribution that is determined by the numerical aperture of emission. Light fluxes on one side (half the angle determined by the exit numerical aperture) from the center line of the divergent light flux enter the optical fibers 12a, 12b, 12c, respectively. Conversely, optical fiber 12a,
The light fluxes emitted from 12b and 12c diverge with an angular distribution determined by the emission numerical aperture of each optical fiber and enter the optical fiber 11, but the incident angle on the optical fiber 11 is larger than the incident limit angle determined by the optical fiber 11. In other words, the light rays wider than the angle of incidence are optical fibers.
Although it reaches the end face of No. 11, it does not work effectively for the light propagation in the optical fiber because it is larger than the optical fiber incident limit angle, and it is not effectively used as an optical branching coupling element.
In order to realize highly efficient optical coupling, it is preferable that the luminous flux on one side of the center line of the divergent luminous flux be equal to the light receiving angle corresponding to the incident numerical aperture of the optical fibers 12a, 12b, 12c, as shown in FIG. It is difficult to perform such high-efficiency optical coupling in such an optical branching coupling element of the related art.

The present invention has been made in view of the above points, and an object thereof is to solve the above-mentioned problems, to achieve a desired optical branching ratio, a high coupling efficiency, and a high productivity. An object of the present invention is to provide an optical branching / coupling element that can be made at a high price.

[0007]

In order to achieve the above object, there is provided a first curved surface for reflecting and deflecting a part of a light beam emitted from the end face of the first optical fiber and diverging according to the emission numerical aperture of the first optical fiber. Arranged opposite the first curved surface,
The light beam reflected and deflected by the first curved surface is reflected and deflected by the second
A second curved surface incident on the end face of the optical fiber,
A unit optical element in which a first curved surface and a second curved surface are arranged so that the light beam reflected and deflected by the curved surface enters the second optical fiber at an incident angle corresponding to the incident numerical aperture of the second optical fiber. A plurality of unit optical elements are provided, and the plurality of unit optical elements share the first optical fiber.

Further, a second curved surface for reflecting and deflecting a light flux emitted from the end face of the second optical fiber and diverging according to the emission numerical aperture of the second optical fiber, and a second curved surface which is disposed so as to face the second curved surface and is reflected by the second curved surface. A first curved surface that reflects / deflects the deflected light flux and enters the end face of the first optical fiber, and the light flux reflected / deflected by the second curved surface is incident on the first optical fiber in accordance with the incident numerical aperture. A plurality of unit optical elements in which a first curved surface and a second curved surface are arranged so as to enter the first optical fiber within an angle, and the plurality of unit optical elements share the first optical fiber. And

Further, in the optical branching / coupling element having the above structure, the first and second curved surfaces are paraboloids of revolution, and the rotation axes of the paraboloids of revolution are arranged parallel to each other. It is assumed that the end faces of the optical fibers are arranged at the respective focal positions on the object surface. Furthermore, in the optical branching / coupling element having the above-described configuration, the first curved surface is any one of a paraboloid of revolution, a ellipsoid of revolution and a spherical surface, and the second curved surface is a paraboloid of revolution and ellipsoid of revolution. A curved surface of any one of a surface and a spherical surface, which is emitted from the end surface of the first optical fiber, and which is reflected and deflected by the first curved surface to form an image,
It is assumed that the image-formed light flux is reflected and deflected by the second curved surface and is incident on the end face of the second optical fiber.

Further, in the optical branching / coupling device having the above structure, the first curved surface is any one of a paraboloid of revolution, a ellipsoid of revolution and a spherical surface, and the second curved surface is a paraboloid of revolution. It is any one of a spheroidal surface and a spherical surface, and the light flux emitted from the end face of the second optical fiber and reflected / deflected by the second curved surface forms an image, and this imaged light flux forms the first curved surface. It is assumed that it is reflected and deflected, and is incident on the end face of the first optical fiber.

Further, in the optical branch-coupling element having the above structure, the light reflecting film is formed on the curved surface of the optical element. In addition, in the optical branching and coupling element having the above structure, the light reflecting film is formed on the inner surface of the optical element formed in a hollow shape. Further, in the optical branching / coupling element having the above-mentioned configuration, it is assumed that the light emitted from the optical fiber is totally reflected by the curved surface of the optical element.

[0012]

With the above structure, the light flux emitted from the focal point of the paraboloid is reflected / deflected on the paraboloid, travels parallel to the rotation axis of the paraboloid, and vice versa. When such a light flux is incident, this light flux is used to converge at the focal point of the paraboloid. That is, the light flux emitted from the optical fiber arranged at the focal point of the first paraboloid is reflected and deflected by the first paraboloid, and travels in parallel with the rotation axis of the paraboloid. This light beam is reflected and deflected by the opposing second parabolic surfaces whose rotation axes are parallel to each other, and enters the second optical fiber. Second
The parabolic surface of does not need to have the same focal length as the first parabolic surface, and the light flux traveling parallel to the rotation axis of the parabolic surface is reflected and deflected by the second parabolic surface, Entrance numerical aperture NA
High binding efficiency can be obtained by selecting a paraboloid that matches with.

Further, in the optical branching / coupling element having the above-mentioned structure, the property that the light flux diverging from the focal point of the spheroidal surface is condensed to the other focal point, the optical fiber disposed at the focal point of the first elliptic surface is used. The emitted light beam is reflected and deflected by the first ellipsoidal surface, and is condensed at a virtual point in the optical path which is another focal point of the ellipsoidal surface. This light beam is reflected and deflected by the second ellipsoidal surface (one focal point of this elliptical surface is arranged at a virtual point), and is incident on the second optical fiber arranged at the focal position of the second elliptical surface. . By appropriately selecting the focal length and major axis of the second spheroid, the incident numerical aperture NA of the second optical fiber can be matched.

The above-mentioned matter also holds for a combination of a paraboloid of revolution and an ellipsoid of revolution, and an image is formed by displacing the position of the end face of the fiber from the focal point of the paraboloid, and the ellipse of the ellipsoid is formed at this imaging position. You may focus on one side. Further, the above matter may be a combination of a spherical surface and a paraboloid of revolution, a spheroid of revolution, or a sphere.

[0015]

FIG. 1 shows an embodiment of an optical branching / coupling element according to the present invention. FIG. 1 (a) is a cross-sectional view of a main part, and FIG.
2A and 2B show another embodiment of the optical branching / coupling device according to the present invention. FIG. 2A is a perspective view and FIG. 2B is a top view. FIG. 3 is a principle view of the present invention, and FIG. 4 is a sectional view of a main part of still another embodiment of the unit optical element. The same members as those in FIG. 5 are designated by the same reference numerals. is there.

The optical branching and coupling element of the embodiment of FIG. 1 shows a case where it is composed of two unit optical elements 5a and 5b whose light paths are particularly easy to understand, and three optical fibers 11, 12a and 12b are arranged at predetermined positions. It is located at O ₁ , Oa ₂ , and Ob ₂ . Unit optical element 5
a and 5b have the same shape and are symmetrical with respect to a plane perpendicular to the plane of the paper including the center line of the optical fiber 11 (passing through the position O ₁ ). The unit optical element 5a will be described as a representative with reference to FIG. The unit optical element 5a has a first light reflection surface.
The member 5a ₁ having the curved surface Sp ₁ and the member 5a ₂ having the second curved surface Sp 2 arranged to face the first curved surface Sp 1 are configured as an integral structure. The light-reflecting surfaces of the members 5a ₁ and 5a ₂ are, for example, a part of a rotating paraboloid whose center of rotation is an axis including the focal point of the parabola and perpendicular to the quasi-line, or rotation about the major axis of the ellipse. It corresponds to a part of the ellipsoidal surface or a part of the spherical surface. The end face of the first position corresponding to the curved surface Sp1 (generally the focal position corresponding) O ₁ to the optical fiber 11, the end face of the optical fiber 12a to the position Oa ₂ corresponding to the second curved surface Sp2 is arranged, from the position O ₁ Part of the emitted light beam is reflected and deflected by the first curved surface Sp1 and
The light enters the curved surface Sp2, is reflected and deflected, and moves to the position Oa ₂
It is incident on the optical fiber 12a arranged at. The reversibility of light also allows light to travel the reverse path.

The boundary between the end faces of the members 5a ₁ and 5b ₁ of the unit optical elements 5a and 5b is a position perpendicular to the paper surface including the center line (including the position O ₁ ) of the optical fiber 11, and both unit optical elements 5a ,Five
b joins here, sharing position O ₁ and optical fiber 11. In the embodiment of FIG. 1, the first curved surface Sp1 and the second curved surface
The case where a part of the paraboloid of revolution is used as Sp2 is shown. The light beam emitted from the end surface of the optical fiber 11 arranged at the focal point O ₁ diverges with an angular distribution determined by the numerical aperture of the optical fiber 11 and spreads within the range indicated by the dotted lines 8a and 8b, and both first curved surfaces Sp1 Incident on. At this portion, the light flux of 8a is reflected and deflected to the left by the first curved surface Sp ₁ of the member 5a ₁ ,
It travels parallel to the rotation axis of curved surface Sp1 (rotational paraboloid). Since the rotation axis of the second curved surface Sp2 is parallel to the rotation axis of the first curved surface Sp1, the light flux traveling in parallel is further reflected and deflected by the second curved surface Sp2 to be condensed at the focal point Oa ₂ and the optical fiber.
It is incident on 12a. The light beam emitted from the optical fiber 12a passes through a path opposite to the above, is reflected and deflected by the portion indicated by 8a, and enters the optical fiber 11. The light beam in the portion 8b is deflected to the right, is focused on the focus Ob _{2 along} the same path, and is incident on the optical fiber 12b. Similarly, the light beam emitted from the optical fiber 12b is reflected and deflected by the portion indicated by 8b and enters the optical fiber 11.

FIG. 2 shows another embodiment of the optical branching / coupling device, which is composed of three unit optical devices 5a, 5b and 5c, and four optical fibers 11, 12a, 12b and 12c are provided in a predetermined structure. position
It is located at O ₁ , Oa ₂ , Ob ₂ and Oc ₂ . This optical element 5a, 5b,
5c has the same shape as each other, and has a rotationally symmetric structure about the center line (passing the position O ₁ ) of the optical fiber 11. The unit optical element 5a (5b, 5c) has the same structure as that described in FIG. 1, and has a member having a first curved surface Sp1 as a light reflecting surface.
5a ₁ (5b ₁ , 5c ₁ ) and a member 5a ₂ (5b ₂ , 5c ₂ ) having a second curved surface Sp2 that is arranged to face the first curved surface Sp1.

The light reflecting surfaces of the members 5a ₁ and 5a ₂ are, for example,
A part of a paraboloid of revolution, a spheroid of revolution or a sphere corresponds to this. The end surface of the optical fiber 11 is located at the position corresponding to the first curved surface Sp 1 (generally, the focal point corresponds) O ₁ and the second curved surface Sp 1.
The end face of the optical fiber 12a is arranged at the position Oa ₂ corresponding to 2, and the part 8a (8b, 8c) of the light beam emitted from the position O ₁ is the first curved surface Sp1 of the member 5a ₁ (5b ₁ , 5c ₁ ). Reflected and deflected,
The light enters the second curved surface Sp2 and is further reflected and deflected
Optical fiber 12a (12b, 12c) placed in Oa ₂ (Ob ₂ , Oc ₂ ).
Incident on. Also, due to the reversibility of light, it is possible to pass light in the reverse path.

Members 5a ₁ , 5b ₁ , 5c _{1 of the} unit optical elements 5a, 5b, 5c
Includes the central axis of the optical fiber 11 and is 60 to the left and right of this axis.
Unit optical elements that are bonded to each other at surfaces that form an angle of °
5a, 5b, 5c are spliced here and are configured to share position O ₁ and optical fiber 11. A case where a paraboloid of revolution is used as the light reflecting surface will be described with reference to FIG. First curved surface
Sp ₁ includes a focal point F ₁ and is a part of a paraboloid of revolution having an axis perpendicular to the normal line as an axis of rotation 14, and the end surface of the optical fiber 11 is located at the focal point F ₁ (corresponding to the focal point O ₁ in FIG. 1). It is arranged. Second
Curved Sp2 includes a focus F _2, Ri is a part of a paraboloid of revolution and the rotation axis 15 of the axis perpendicular to the directrix, the rotary shaft 14 and 15 are disposed parallel to one another, the focal point F ₂ ( The end faces of the optical fibers 12a (12b) are arranged at the focal points Oa ₂ and Ob ₂ in FIG. The dotted line shown on the right side of the perpendicular to the focal point F ₁ on the first curved surface Sp 1 is a virtual extension line of the curved surface Sp ₁ , and in reality, the member 5b ₁ is symmetrically arranged at this portion and is integrally structured with the member 5a _1. ing.

As described above, the light flux emitted from the optical fiber 11 diverges with an angular distribution determined by the emission numerical aperture of the optical fiber, and the emitted light on the left side of the perpendicular line passing through the focal point F ₁ (that is, the center line of the optical fiber 11) is a curved surface. It is reflected and deflected by Sp1 and travels parallel to the rotation axis 14. This reflected light is a curved surface Sp2
It is reflected and deflected by, and the rotation axes 14 and 15 are parallel, so the focus
It is incident on F ₂ . By selecting the focal length F ₂ appropriately,
A large part of the luminous flux emitted from the optical fiber 11 and reflected / deflected by the curved surface Sp1 is received at an incident angle corresponding to the incident numerical aperture of the optical fiber 12a (12b), that is, the incident limit angle.
Can be combined with. Conversely, the optical fiber 12a
The light emitted from (12b) can be converged within the incident limit angle of the optical fiber 11.

FIG. 3B shows a spheroidal surface Se1, Se as a light reflecting surface.
This is the case when 2 is used. 3 (a) is different from FIG. 3 (a).
Is a parallel ray after being reflected on the first curved surface, whereas FIG. 3 (b) shows that it forms an image and has a _third focal point F3. 3 (b), the curved surface Se1 is the focus of F _1, F _3, a part of the spheroid to the rotation axis of a major axis passing through the F _1, F _3, the curved surface Se2 is F _2, F ₃ It is a part of a spheroid having a focal point and a major axis passing through F ₂ and F ₃ as an axis of rotation, and both axes of rotation are on the same plane and intersect each other. At the focal point F ₁ (corresponding to the focal point O ₁ in FIG. 1), the optical fiber 11 moves to the focal point F ₁ .
Optical fiber 1 to ₂ (corresponding to focal points Oa ₂ and Ob ₂ in Fig. 1)
2a (12b) are arranged respectively.

As described above, the luminous flux emitted from the optical fiber 11 diverges with an angular distribution determined by the numerical aperture of the optical fiber, and the outgoing light on the left side of the center line of the optical fiber 11 arranged at the focal point F ₁ is reflected by the curved surface Se 1. Deflected and focused
Focus on F ₃ . This light flux is further reflected and deflected by the curved surface Se ₂ and enters the optical fiber 12a (12b) arranged at the focal point F ₂ . By appropriately selecting the focal length and major axis of the spheroidal surface, most of the light flux emitted from the optical fiber 11 and reflected / deflected by the curved surface Se1 can be converged to the incident limit angle of the optical fiber 12a (12b). Conversely, optical fiber
The light flux emitted from 12a (12b) can be converged within the incident limit angle of the optical fiber 11.

Although not shown, the curved surfaces Sp1 and Se
When combining 2, if the end face of the optical fiber is located far from the focal position of Sp1, and the resulting imaging position based on the converging property is F ₃ , and the focus of Se 2 is F ₃ ,
The light emitted from the optical fiber 11 can be converged to the incident limit angle of the optical fiber 12a. Similarly, when the curved surfaces Se1 and Sp2 are combined, they can be converged to the incident limit angle.

Further, there is a spherical surface as a special case of the spheroid. In this case, the center of the sphere is the focal point, but if one point on the spherical surface excluding the center of the sphere is selected, there is a problem of image distortion, but there is an imaging point corresponding to this. That is, the figure
By arranging one end face of the optical fiber and the image forming point at the corresponding point in 3 (b), the same effect can be obtained with a fiber having a large core diameter such as a plastic optical fiber.

The optical branching / coupling element of the present invention uses, as a light path, a light propagation path inside the members 5a ₁ and 5a ₂ of the unit optical element, and a cavity formed by the member instead of inside the member. There is something to propagate. FIG. 1 described above is an example belonging to the former, and it corresponds to the principle diagram (parallel rays) of FIG. 3 (a). The vicinity where the curved surfaces Sp1 and Sp2 intersect may be flat. In addition, as a design modification, for example, as shown in FIG.
It is also possible to make a fiber insertion hole at the F ₂ position to facilitate the attachment of the fiber. Further, although not shown in FIG. 1, there is also one using a spheroidal surface corresponding to the principle diagram of FIG. 3 (b) (a light beam is imaged at F ₃ ). In this case focus F ₁ , F ₂
In the vicinity of the position, in order to improve the coupling with the end faces of the optical fibers 11, 12a, 12b, the face of the focal position and the end faces of the optical fibers are parallelized.

In the structure in which the inside of the member of the unit optical element serves as the light propagation path, optical glass such as BK7 or transparent polymer resin such as PMMA is used as the member of the optical element. In addition, the light reflecting surfaces Sp1, S outside the members 5a ₁ and 5a ₂ are
A metal film such as gold may be vapor-deposited on p2 to form a reflective film. Further, in the present structure, the principle of total reflection based on the relationship between the refractive index of the member and the incident angle / reflection angle can be used without forming the reflection film. In this case, the light reflection loss due to the reflection film can be eliminated.

FIG. 4 shows still another embodiment according to the present invention. The difference from the embodiment of FIG. 1 is that the light path propagates light not in the member of the optical branching and coupling element but in the cavity formed by the curved plate member. As an example, the principle diagram of FIG. The corresponding ones are shown. The dotted line portion of FIG. 4 is the unit optical element of FIG.
The position of 5b is shown by an imaginary line. The difference from FIG. 1 is that a reflective film is formed on the inner surface of the optical elements 5a and 5b as a light reflecting surface. Since the path of the light flux is air on the inner surface, there are advantages that there is no light loss due to the members and that the light branching and coupling element can be formed lightly.

The present invention is not limited to the above embodiment, and there are various modifications. Specifically, in the above embodiment, the number of optical elements of the optical branching / coupling element was described as two and three, but the number is not limited to this. For example, by joining N optical members to each other, a 1: N branched bond can be realized. In this case, the joint surface where the optical elements are in contact with each other is selected to be 180 ° / N to the left and right of the rotation center axis. In addition, the light can be branched or combined at a desired branching ratio by configuring the optical element by changing the size of the optical element without selecting the same angle.

In the illustrated example, the optical fibers 12a, 12b, 12
Although c is shown vertically, it may be tilted. In this case, the total reflection type element can be designed more easily.

[0031]

As described above, according to the present invention, by reflecting the light flux at least twice, the fiber
The light flux emitted from 11 is assigned to a plurality of light receiving fibers, and these light receiving fibers 12a, 12b, ---- are made to enter at an angle corresponding to the incident numerical aperture, and conversely, the fibers 12a, 12
Since all the light beams emitted from b, ---- can be made incident on the fiber 11, it is possible to branch / couple light having a desired branching ratio and high coupling efficiency.

Further, a structure utilizing total reflection can be realized without using a reflection film, and an optical branching coupling element with little optical loss can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an embodiment of the present invention.

FIG. 2 is a schematic explanatory view of another embodiment of the present invention.

FIG. 3 is an explanatory view of the principle of the unit optical element of the present invention.

FIG. 4 is an explanatory view of a modified example of the unit optical element of the present invention.

FIG. 5 is a schematic explanatory view of a conventional optical branching / coupling element.

[Explanation of symbols]

5a, 5b, 5c Optical element 5a ₁ , 5b ₁ , 5c ₁ First curved member 5a ₂ , 5b ₂ , 5c ₂ Second curved member 8a, 8b, 8c Fiber 11 divergent light flux 11 Optical fiber 12a, 12b, 12c Optical fiber 14, 15 Rotation axis O ₁ Optical fiber end face Oa ₂ , Ob ₂ , Oc ₂ Optical fiber end face F ₁ , F ₂ , F ₃ Focus Sp1, Sp2 Rotation paraboloid Se1, Se2 Spherical ellipsoid

Claims (8)

[Claims] 1. A first optical fiber is emitted from an end face of the first optical fiber,
A first curved surface that reflects / deflects a part of the light flux diverging according to the exit numerical aperture of the optical fiber, and a first curved surface that is arranged so as to face the first curved surface, reflects / deflects the light flux reflected / deflected by the first curved surface, and A second curved surface which is incident on the end face, and the light flux reflected and deflected by the first curved surface is incident on the second optical fiber at an incident angle corresponding to the incident numerical aperture of the second optical fiber; An optical branching / coupling device comprising a plurality of unit optical elements each having a second curved surface, the plurality of unit optical elements sharing the first optical fiber. 2. The light is emitted from the end face of the second optical fiber,
A second curved surface that reflects / deflects a light beam diverging according to the numerical aperture of the optical fiber, and is arranged to face the second curved surface,
The light beam reflected and deflected by the second curved surface is reflected and deflected by the first
A first curved surface incident on the end face of the optical fiber,
A unit optical element in which a first curved surface and a second curved surface are arranged so that the light flux reflected and deflected by the curved surface enters the first optical fiber within an incident angle corresponding to the incident numerical aperture of the first optical fiber. An optical branching / coupling element comprising a plurality of unit optical elements, wherein the plurality of unit optical elements share the first optical fiber. 3. The optical branch-coupling element according to claim 1 or 2, wherein the first and second curved surfaces are paraboloids of revolution, and the rotation axes of the paraboloids of revolution are arranged parallel to each other. An optical branching / coupling element, which is provided, and an end face of an optical fiber is arranged at each focal position of these paraboloids of revolution. 4. The optical branching / coupling element according to claim 1, wherein the first curved surface is any one of a paraboloid of revolution, a spheroid of revolution and a spherical surface, and the second curved surface is a revolution parabolic surface. A curved surface of any one of an object surface, a spheroid, and a spherical surface, which is emitted from the end face of the first optical fiber and reflected by the first curved surface.
An optical branching / coupling element characterized in that a deflected light beam forms an image, and the imaged light beam is reflected and deflected by a second curved surface and is incident on an end face of a second optical fiber. 5. The optical branching / coupling element according to claim 2, wherein the first curved surface is any one of a paraboloid of revolution, a spheroid of revolution, and a spherical surface, and the second curved surface is a revolution paraboloid. A curved surface of any one of an object surface, a spheroid, and a spherical surface, which is emitted from the end surface of the second optical fiber and reflected by the second curved surface.
An optical branching / coupling element characterized in that a deflected light beam forms an image, and the imaged light beam is reflected and deflected by a first curved surface and is incident on an end face of a first optical fiber. 6. An optical branching / coupling element according to claim 1, wherein a light reflecting film is formed on a curved surface of the optical element. . 7. The optical branching coupling element according to any one of claims 1 to 5, wherein a light reflecting film is formed on the inner surface of the hollow optical element. Optical branch coupling device. 8. The optical branching / coupling element according to claim 1, wherein the light emitted from the optical fiber is totally reflected by the curved surface of the optical element. .