JP2007017701A - Single core bidirectional optical transceiver module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single core bidirectional optical transceiver module in which coupling efficiency with an optical fiber is further enhanced. <P>SOLUTION: The transceiver module is equipped with a light emitting element 2 for emitting light of a first wavelength, an optical filter 5 arranged in the optical path of the first wavelength light 3 outgoing from the light emitting element 2, an optical fiber 6, and a light receiving element 8. The optical fiber 6 is provided with an inclined end face 6a in which light receiving sensitivity has distribution with an elliptical shape orthogonal to the optical axis Z. The light emitting element 2 and the optical fiber 6 are arranged in the manner that the rotation angle θc around the optical axis of the elliptical light intensity distribution C in the first wavelength light 3 from the light emitting element 2 coincides with the rotation angle θd around the optical axis Z of the light receiving sensitivity distribution D in the inclined end face 6a of the optical fiber 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a module for optical communication, and more specifically, a light receiving element is disposed outside an optical path connecting a light emitting element, an optical filter, and an optical fiber, and light from the light emitting element is guided to the optical fiber. In addition, the present invention relates to a single-core bidirectional optical transceiver module in which emitted light from the optical fiber is guided to a light receiving element.

  Conventionally, in an optical communication device, various modules are used to transmit and receive optical signals. For example, the following Patent Document 1 discloses an optical transmission / reception module shown in a schematic configuration diagram in FIG. The optical transceiver module 101 is a single-core bidirectional optical transceiver module.

  The optical transceiver module 101 includes a laser diode 102 that is a light emitting element. An optical fiber 103 is arranged so that light from the laser diode 102 is guided. A convex lens 104 and a demultiplexing filter 105 as an optical filter are disposed between the laser diode 102 and the optical fiber 103. That is, the convex lens 104 and the demultiplexing filter 105 are disposed along an optical path through which light is guided from the laser diode 102 to the optical fiber 103.

  The convex lens 104 is provided for converging light having the first wavelength emitted from the laser diode 102. The converged light passes through the demultiplexing filter 105 and is guided to the optical fiber 103. The optical fiber 103 has an inclined end surface 103a. The demultiplexing filter 105 has a plate shape, and the main surface is inclined with respect to the optical axis of the optical path.

  On the other hand, the light of the second wavelength emitted from the optical fiber 103 through the inclined end face 103a is arranged outside the optical path via the convex lens 106 arranged outside the optical path by the action of the demultiplexing filter 105. Guided to the photodiode 107.

In the optical transceiver module 101, the optical fiber 103 has an inclined end surface 103a in order to prevent the light from the laser diode 102 from being reflected by the end surface 103a of the optical fiber 103 and returning. The inclination direction of the inclined end face 103a and the inclination direction of the demultiplexing filter 105 are opposite to each other. As a result, the astigmatism generated by the demultiplexing filter 105 disposed in the optical path through which the light converged by the convex lens 104 is guided is canceled by the reverse tilt structure, and the coupling efficiency to the optical fiber 103 is increased. Yes.
JP 2003-307656 A

  In the optical transmission / reception module 101 described in Patent Document 1, as described above, the demultiplexing filter 105 is tilted in the direction opposite to the tilting direction of the inclined end surface 103 a of the optical fiber 103, thereby the demultiplexing filter 105. Astigmatism caused by 105 is canceled out, thereby suppressing a decrease in coupling efficiency to the optical fiber 103.

  However, since the demultiplexing filter 105 is inclined in the optical transceiver module 101, the light intensity distribution of the light having the first wavelength emitted from the laser diode 102 is converted when passing through the demultiplexing filter 105. Is done.

  On the other hand, the inclined end surface 103a of the optical fiber 103 is inclined in order to suppress the reflected return light, as described above. Therefore, the inclined end surface 103a has a light receiving sensitivity distribution with respect to incident light. In this case, it has an elliptical distribution in a plane orthogonal to the optical axis of the optical path. Therefore, when the light intensity distribution of the light having the first wavelength that has passed through the demultiplexing filter 105 does not match the elliptical light receiving sensitivity distribution on the inclined end surface 103a, the coupling efficiency to the optical fiber 103 is reduced. Will not be good enough.

  Therefore, the conventional single-core bidirectional optical transceiver module described in Patent Document 1 has a problem that the optical coupling efficiency to the optical fiber is not yet sufficient.

  In view of the current state of the prior art described above, the present invention provides a single-core bidirectional device that includes an optical filter that is inclined with respect to the optical axis of an optical path and an optical fiber that is provided with an inclined end face to suppress reflected return light. It is an optical transmission / reception module, which is to provide a single-core bidirectional optical transmission / reception module capable of further increasing the coupling efficiency to an optical fiber.

  1st invention of this application is arrange | positioned in the optical path of the light of the said 1st wavelength radiate | emitted from the light emitting element which emits the light of 1st wavelength, and with respect to the optical axis of this optical path And an optical filter that is inclined, and is disposed on the side of the optical path opposite to the light emitting element via the optical filter, and the light having the first wavelength is incident thereon and the light having the second wavelength And a light receiving element for receiving the light of the second wavelength by guiding the light of the second wavelength in a direction different from the optical path by the optical filter. In the single-core bidirectional optical transceiver module, the light having the first wavelength emitted from the light emitting element has a first elliptical light intensity distribution in a direction perpendicular to the optical axis of the optical path. Photosensitivity at the inclined end face of the fiber Has a second elliptical shape distribution orthogonal to the optical axis, and rotation of the first elliptical light intensity distribution around the optical axis in the light of the first wavelength emitted from the light emitting element. The light emitting element and the optical fiber are arranged so that the angle coincides with a rotation angle around the optical axis of the second elliptic light receiving sensitivity distribution on the inclined end face of the optical fiber. To do.

  According to a second aspect of the present invention, a light emitting element that emits light of a first wavelength, and an optical path of the light of the first wavelength emitted from the light emitting element, and inclined with respect to the optical axis of the optical path In the optical path, the optical filter is disposed on the opposite side of the light emitting element via the optical filter, and the light having the first wavelength is incident and the light having the second wavelength is emitted. And an optical fiber having an inclined end face, and further comprising a light receiving element that guides light of the second wavelength in a direction different from the optical path by the optical filter and receives the light of the second wavelength. In the single-core bidirectional optical transceiver module, light having a first wavelength emitted from the light emitting element has a first elliptical light intensity distribution in a direction orthogonal to the optical axis of the optical path. The light sensitivity on the inclined end face is A rotation angle around the optical axis of the first elliptical light intensity distribution after passing through the optical filter, and having a second elliptical shape distribution orthogonal to the optical axis, and the tilt of the optical fiber The rotation angle around the optical axis of the second elliptic light-receiving sensitivity distribution on the end face is the same.

  In the present invention, the light emitting element is not particularly limited, but in a specific aspect of the present invention, a laser diode that is widely used in an optical transceiver module is used as the light emitting element.

  In another specific aspect of the single-core bidirectional optical transceiver module according to the present invention, the thickness of the optical filter is preferably 0.5 mm or less.

  In still another specific aspect of the single-core bidirectional reception module according to the present invention, the optical filter has a structure in which a plurality of dielectric layers are stacked on a polyimide substrate.

  In the single-core bidirectional optical transceiver module according to the first invention, even if the light intensity distribution is converted when the light of the first wavelength emitted from the light emitting element passes through the optical filter, The light emitting element and the light so that the rotation angle around the optical axis of the elliptical light intensity distribution matches the rotation angle around the optical axis of the light reception sensitivity distribution of the second elliptical shape on the inclined end face of the optical fiber. Since the fiber is arranged, the coupling efficiency to the optical fiber can be further increased.

  That is, in the conventional single-core bidirectional optical transceiver module, when the tilt direction of the tilted end surface of the optical fiber is opposite to the tilt direction of the optical filter, astigmatism caused by the optical filter is canceled out. Although the coupling efficiency could be increased, it was not yet sufficient.

  In contrast, according to the present invention, as described above, the rotation angle around the optical axis of the light intensity distribution of the first wavelength is the rotation angle around the optical axis of the light reception sensitivity distribution at the inclined end face of the optical fiber. Therefore, it is possible to further suppress a decrease in optical coupling efficiency accompanying a change in light intensity distribution when passing through the optical filter.

  Therefore, according to the present invention, it is possible to provide a single-core bidirectional optical transceiver module that can guide light of the first wavelength to the optical fiber with high efficiency.

  When the rotation angle around the optical axis of the inclined end face of the optical fiber is matched with the rotation angle around the optical axis of the light intensity distribution after passing through the optical filter of the light of the first wavelength, The rotation angle around the optical axis of the light receiving sensitivity distribution at the inclined end face of the optical fiber can be made coincident with the rotation angle around the optical axis of the light intensity distribution of the light of the first wavelength. That is, in arranging the light emitting element and the optical fiber, it is possible to easily provide an optical transceiver module with improved coupling efficiency only by adjusting the rotation angle around the optical axis of the inclined end surface of the optical fiber according to the present invention. it can.

  Therefore, the rotation angle around the optical axis of the light receiving sensitivity distribution at the inclined end face of the optical fiber does not necessarily match the rotation angle around the optical axis of the light intensity distribution of the first wavelength before passing through the optical filter. . That is, as in the second invention, the rotation angle around the optical axis of the light intensity distribution of the first wavelength after passing through the optical filter is set to the rotation angle around the optical axis of the light receiving sensitivity distribution at the inclined end face of the optical fiber. Coupling efficiency can be increased simply by adjusting the rotation angle around the optical axis of the inclined end face of the optical fiber so that they match.

  In the present invention, the light-emitting element is not particularly limited, but when a laser diode is used, the light emitted from the laser diode is usually in the shape of an ellipse in the plane perpendicular to the optical axis. Usually it has a distribution. Therefore, when a laser diode is used as the light emitting element, the optical fiber is made to coincide with the rotation angle of the light intensity distribution of the laser diode around the optical axis in accordance with the present invention. The coupling efficiency can be effectively increased.

  Note that as the optical filter is thinner, the coupling loss to the optical fiber can be reduced, and therefore the coupling efficiency can be increased. Conventionally, it has been difficult to reduce the thickness of this type of optical filter having a structure in which a plurality of dielectric thin films are laminated on a glass substrate to 0.5 mm or less, but polyimide is used instead of the glass substrate. By using it, it is possible to easily construct an optical filter of 0.5 mm or less, thereby effectively increasing the coupling efficiency to the optical fiber.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  1A and 1B are schematic configuration diagrams of a single-core bidirectional optical transceiver module according to an embodiment of the present invention. The optical transceiver module 1 according to the present embodiment includes a light emitting element 2. The light emitting element 2 is not particularly limited, but is configured using a laser diode in the present embodiment. The light emitting element 2 may be configured using a light emitting element such as an LED other than the laser diode 2.

  From the laser diode 2, light 3 having the first wavelength is emitted. In the optical path of the light 3 having the first wavelength, the convex lens 4, the optical filter 5, and the optical fiber 6 are arranged in this order. The convex lens 4 is provided to converge the light 3 having the first wavelength and guide it to the optical filter 5. The light having the first wavelength that has passed through the optical filter 5 is incident on the inclined end surface 6 a of the optical fiber 6. The optical filter 5 is inclined with respect to the optical axis of the optical path of the light having the first wavelength. On the other hand, the inclined end surface 6a is also inclined with respect to the optical axis. The inclination direction of the optical filter 5 and the inclination direction of the inclined end surface 6a are opposite to each other.

  The optical filter 5 is made of a plate-like optical material. More specifically, although not particularly limited, the optical filter has an antireflection film on at least one surface of a structure in which a plurality of dielectric layers are laminated on a glass substrate or a structure in which a plurality of dielectric layers are laminated on a glass substrate. Have a laminated structure.

  As described above, the main surface of the optical filter 5 is inclined with respect to the optical axis Z of the optical path of the light 3 having the first wavelength. The inclination angle is about 45 degrees with respect to the optical axis Z.

  On the other hand, a convex lens 7 and a light receiving element 8 are disposed at a position away from the optical path of the light 3 having the first wavelength. Light having the second wavelength is emitted from the inclined end surface 6 a of the optical fiber 6, reflected by the optical filter 5, and guided to the convex lens 7. The light 9 having the second wavelength is converged by the convex lens 7 and received by the light receiving element 8. As the light receiving element 8, an appropriate photoelectric conversion element such as a photodiode can be used.

  As described above, in the optical transceiver module 1, the first wavelength light 3 emitted from the light emitting element 2 is guided to the optical fiber 6, and the second wavelength light 9 emitted from the optical fiber 6 is received. It is configured to be guided to the element 8. The optical filter 5 is disposed to guide the light 9 having the second wavelength to the light receiving element 8. The inclined end face 6a is provided to prevent the light 3 having the first wavelength from being reflected by the end face of the optical fiber 6 and returning from the light emitting element 2. That is, the inclined end surface 6a is provided to suppress the reflected return light.

  In addition, in the present embodiment, the tilt direction A of the optical filter 5 and the tilt direction B of the tilted end surface 6a are opposite to each other as in the optical transceiver module 101 described in Patent Document 1. That is, as shown in FIG. 1 (a), the tilt direction A is parallel to the main surface of the optical filter 5, passes through the optical axis Z, and ends at a point closest to the optical fiber 6. The inclination direction B is a vector direction that is parallel to the inclined end face 6a, passes through the optical axis Z, and ends at the end closest to the optical filter 5 side. When the inclination direction A and the inclination direction B are the same direction, the inclination direction A and the inclination direction B are parallel. In contrast, in the present embodiment, as in the case of the optical transceiver module described in Patent Document 1, the inclined direction B of the inclined end surface 6a is opposite to the inclined direction A of the optical filter 5. Is stipulated. Accordingly, a decrease in coupling efficiency to the optical fiber 6 due to astigmatism when passing through the optical filter 5 is suppressed.

  In addition, in this embodiment, the rotation angle around the optical axis Z of the light intensity distribution of the light 3 having the first wavelength is made to coincide with the rotation angle around the optical axis Z of the light receiving sensitivity distribution on the inclined end surface 6a. The light emitting element 2 and the optical fiber 6 are disposed. This will be described with reference to FIGS. 1B and 1C.

  FIG. 1B is a schematic perspective view for schematically explaining the light intensity distribution of the light having the first wavelength that has passed through the optical filter 5. The light having the first wavelength guided from the light emitting element 2 to the optical filter 5 has an elliptical light intensity distribution located in a plane orthogonal to the optical axis Z. In particular, when a laser diode is used as the light-emitting element 2, the emitted light has an elliptical light intensity distribution because the light emission angle of the laser diode is different between the vertical direction and the horizontal direction. This ellipse is the first ellipse. The first elliptical light intensity distribution fluctuates when it passes through the optical filter 5.

  In the present embodiment, even if the light intensity distribution fluctuates when passing through the optical filter 5 as described above, the coupling efficiency to the optical fiber 6 can be effectively increased.

  In FIG. 1B, light emitted from the light emitting element 2 passes through the optical filter 5 and its light intensity distribution varies, but has a first elliptical light intensity distribution C. The major axis of the first elliptical light intensity distribution C is represented by c as shown in FIG.

  On the other hand, the inclined end surface 6 a of the optical fiber 6 is inclined with respect to the optical axis Z so as to be in the inclination direction B. Accordingly, when the light of the first wavelength guided along the optical axis Z is incident on the optical fiber 6 from the inclined end surface 6a, the light receiving sensitivity is not uniform around the optical axis Z. As shown by the second ellipse D shown in 1 (c), it has an elliptical shape. The major axis direction of the second elliptic light-receiving sensitivity distribution D is d.

  In the present embodiment, the major axis c and the major axis d coincide with each other, in other words, the rotation angle θc around the optical axis Z of the light intensity distribution C and the rotation around the optical axis Z of the light receiving sensitivity distribution D. The light emitting element 2 and the optical fiber 6 are arranged so that the angle θd matches. The rotation angle θc around the optical axis Z of the light intensity distribution C is an angle formed by the major axis c with respect to an arbitrarily set reference angular position E around the Z axis, as shown in FIG. It is. Further, the rotation angle θd around the optical axis Z of the light receiving sensitivity distribution D is an angle formed by the major axis d with the reference position D.

  As described above, since the rotation angles θc and θd coincide with each other, it is assumed that the light intensity distribution of the light having the first wavelength that has passed through the optical filter 5 is changed by passing through the optical filter 5. In addition, since the major axis c and the major axis d coincide with each other, the light having the first wavelength is efficiently incident on the optical fiber 6 from the inclined end face 6a.

  The reference position E may be set at any position around the Z axis.

  Therefore, according to the present invention, it is possible to suppress a decrease in the optical coupling efficiency to the optical fiber 6 due to the conversion of the light intensity distribution of the light of the first wavelength when passing through the optical filter 5, and the optical coupling efficiency is reduced. A further improved optical transceiver module can be provided.

  Conventionally, attention has been paid to the inclination direction of the optical filter 5 and the inclination direction of the inclined end face of the optical fiber 6 as described in Patent Document 1, but the first wavelength emitted from the light emitting element 2 No attention has been paid to the relationship between the light intensity distribution of light and the light receiving sensitivity distribution on the inclined end surface 6a. On the other hand, in the present embodiment, as described above, the rotation angle θc around the optical axis Z axis of the light intensity distribution of the light 3 of the first wavelength and the light receiving sensitivity distribution around the optical axis Z in the inclined end surface 6a. By controlling the rotation angle θd, it is possible to realize high optical coupling efficiency to the optical fiber 6 that has not been realized in the past. This will be described based on a specific experimental example with reference to FIGS.

  FIG. 2 shows a case where the rotation angle θc around the optical axis of the major axis c of the first ellipse C showing the light intensity distribution of the light having the first wavelength emitted from the light emitting element 2 is 45 degrees. The change in coupling loss when the rotation angle of the optical fiber 6 is changed as the rotation angle of the light receiving sensitivity distribution of the inclined end face 6a of the optical fiber 6 is shown. The rotation angle of the optical fiber 6 refers to the rotation angle of the inclined end surface 6a around the optical axis, and the rotation angle of the optical fiber and the rotation angle of the light receiving sensitivity distribution of the inclined end surface 6a of the optical fiber 6 are as follows. A one-to-one correspondence is shown.

  3A schematically shows a configuration when the rotation angle of the optical fiber is 0 degrees, and FIG. 3B schematically shows a configuration when the optical fiber is 180 degrees.

  When the rotation angle of the optical fiber shown in FIG. 3A is 0 degree, as described in Patent Document 1, the inclination angle of the optical filter 5 and the inclination direction of the inclined end surface 6a of the optical fiber 6 are reversed. Suppose that it is a direction. As shown in FIG. 3B, when the inclination direction of the inclined end face 6a and the inclination direction A of the optical filter 5 are substantially the same direction, the optical fiber rotation angle is 180 degrees.

  As is apparent from FIG. 2, when the rotation angle of the optical fiber is 0 degree, the optical coupling loss is about −4.75 dB, and when −45 degrees, the order is −4.1 dB. It turns out that it becomes smaller. That is, the coupling loss is smaller when the rotation angle of the fiber is further shifted than when the inclination direction A of the optical filter 5 and the inclination direction B of the inclined end face 6a are reversed. I understand. This is because the rotation angle θc of the light intensity distribution of the light 3 having the first wavelength emitted from the laser diode is 45 degrees, and the rotation angle of the optical fiber is −45 degrees, that is, the rotation angle θd = 45 degrees. In this case, θc and θd coincide with each other, thereby further increasing the coupling loss.

  Therefore, according to the said embodiment, it turns out that the optical coupling efficiency to the optical fiber 6 can be improved effectively.

  As described above, since the rotation angle θd and the rotation angle of the inclined end surface 6a of the optical fiber 6 have a one-to-one correspondence, when setting the rotation angle of the light receiving sensitivity distribution of the optical fiber, the inclined end surface of the optical fiber is set. The rotation angle around the optical axis Z of 6a may be adjusted.

  The optical filter 5 is preferably thinner. FIG. 4 is a diagram showing a change in coupling loss and a change in optical axis deviation when only the thickness of the optical filter 5 is variously changed in the optical transceiver module used in the experimental example.

  As can be seen from FIG. 4, when the thickness of the optical filter exceeds 0.5 mm, the coupling loss increases.

  On the other hand, when the thickness of the optical filter is 0.5 mm or less, it can be seen that the coupling loss can be made relatively small. Therefore, it can be seen that the thickness of the optical filter is desirably 0.5 mm or less in order to reduce the coupling loss and to reduce the optical axis deviation. As shown schematically in FIG. 5 (a) when the thickness of the optical filter is 0.02 mm, and FIG. 5 (b) schematically shows the case where the thickness of the optical filter 5 is 0.5 mm. When the thickness is small, it is considered that the effect of astigmatism by the optical filter is reduced.

(A) is a schematic block diagram of the single core bidirectional | two-way optical transmission / reception module which concerns on one Embodiment of this invention, (b) is a typical perspective view for demonstrating the light intensity distribution of the light of 1st wavelength, (C) is a diagram for explaining the rotation angle θc of the light intensity distribution of the light of the first wavelength and the rotation angle θd around the optical axis of the light reception sensitivity distribution of the optical end face of the optical fiber. When the rotation angle of the light intensity distribution of the light emitted from the light emitting element is 45 degrees and the inclination angle of the optical filter is 45 degrees, the rotation angle around the optical axis Z-axis of the light receiving sensitivity distribution of the inclined end face of the optical fiber The figure which shows the change of the coupling loss to the optical fiber 6 when changing the rotation angle around the optical axis Z-axis of the inclination end surface corresponding to FIG. (A) And (b) is a schematic diagram for demonstrating the rotation angle of the optical fiber of the horizontal axis | shaft of FIG. 2, (a) shows the case where the rotation angle of an optical fiber is 0 degree | times, (b ) Is a diagram schematically showing a case where the rotation angle of the optical fiber is 180 degrees. The figure which shows the coupling loss to an optical fiber at the time of varying the thickness of an optical filter, and the change of optical axis offset. (A) And (b) is a schematic diagram for demonstrating the difference of the effect of astigmatism by the optical filter in case the thickness of an optical filter is 0.2 mm, and 0.5 mm. The schematic block diagram which shows an example of the conventional optical transmission / reception module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical transmission / reception module 2 ... Light emitting element 3 ... Light of 1st wavelength 4 ... Convex lens 5 ... Optical filter 6 ... Optical fiber 6a ... Inclined end surface 7 ... Convex lens 8 ... Light receiving element C ... Light intensity distribution of 1st ellipse c: long axis D: second elliptic light-receiving sensitivity distribution d: long axis Z: optical axis θc, θd: rotation angle

Claims (5)

A light emitting element that emits light of a first wavelength, and an optical filter that is disposed in an optical path of light of the first wavelength emitted from the light emitting element and is inclined with respect to the optical axis of the optical path; The optical path is disposed on the opposite side of the light emitting element via an optical filter, the light having the first wavelength is incident, the light having the second wavelength is emitted, and the inclined end face is An optical fiber having a second wavelength guided by the optical filter in a direction different from the optical path;
A light receiving element that receives the light of the second wavelength is further provided, and the light of the first wavelength emitted from the light emitting element has a first elliptical light intensity distribution in a direction orthogonal to the optical axis of the optical path. In a single-core bidirectional optical transceiver module,
The light receiving sensitivity at the inclined end surface of the optical fiber has a distribution of a second elliptical shape perpendicular to the optical axis,
The rotation angle around the optical axis of the first elliptical light intensity distribution in the light of the first wavelength emitted from the light emitting element, and the second elliptical light receiving sensitivity distribution on the inclined end face of the optical fiber. The single-core bidirectional optical transceiver module is characterized in that the light-emitting element and the optical fiber are arranged so that the rotation angle around the optical axis matches. A light emitting element that emits light of a first wavelength, and an optical filter that is disposed in an optical path of light of the first wavelength emitted from the light emitting element and is inclined with respect to the optical axis of the optical path; The optical path is disposed on the opposite side of the light emitting element via an optical filter, the light having the first wavelength is incident, the light having the second wavelength is emitted, and the inclined end face is An optical fiber having a second wavelength guided by the optical filter in a direction different from the optical path;
A light receiving element that receives the light of the second wavelength is further provided, and the light of the first wavelength emitted from the light emitting element has a first elliptical light intensity distribution in a direction orthogonal to the optical axis of the optical path. In a single-core bidirectional optical transceiver module,
The light receiving sensitivity at the inclined end surface of the optical fiber has a distribution of a second elliptical shape perpendicular to the optical axis,
A rotation angle around the optical axis of the first elliptical light intensity distribution after passing through the optical filter, and a rotation angle around the optical axis of the second elliptical light-receiving sensitivity distribution at the inclined end surface of the optical fiber. Is a single-core bidirectional optical transceiver module, characterized in that   The single-core bidirectional optical transceiver module according to claim 1 or 2, wherein the light emitting element is a laser diode.   The single-core bidirectional optical transceiver module according to claim 1, wherein the optical filter has a thickness of 0.5 mm or less. The single-core bidirectional receiving module according to claim 4, wherein the optical filter has a structure in which a plurality of dielectric layers are stacked on a polyimide substrate.

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