JP2001194560A - Bi-directional optical communication device and bi- directional optical communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and small sized bi-directional optical communication device and bi-directional optical communication equipment in which the whole duplex system communication is performed by one optical fiber and whose transmitting loss in both transmission and reception is small. SOLUTION: Transmitting light 13 radiated from a light emitting element 4 is condensed by a transmission lens 6, passes through the opening part 9 of an optical separation element 8 and is combined to the optical fiber 2. Receiving light 15 radiated from the optical fiber 2 is reflected by a curved surface-like reflecting surface 10 formed on the surface of the optical separation element 8 and is combined to the light receiving element 4. A part of transmitting light 13 (reflected transmitting light 14) reflected by the end surface of the optical fiber 2 whose end surface is inclined is reflected in the outside of the reflecting surface 10 and is not combined to the light receiving element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional communication device capable of transmitting and receiving optical signals in both directions, and more particularly, to home communication and electronic communication using a multimode optical fiber such as a plastic optical fiber as a transmission medium. Communication between devices, L
The present invention relates to a bidirectional optical communication device that can be used for an AN (Local Area Network) or the like.

[0002]

2. Description of the Related Art With the development of the information society, network technology using optical fibers has been receiving attention. Particularly, with the recent trend toward lower loss and wider bandwidth of plastic optical fibers (hereinafter referred to as POF), applications to home communication and communication between electronic devices have been advanced. 2. Description of the Related Art Conventionally, an optical communication device that transmits and receives signal light using an optical fiber as a transmission medium has been mainly a full-duplex type using two optical fibers. However, when two optical fibers are used, there are problems that it is difficult to reduce the size of the optical communication device and that the cost of the optical fibers increases as the transmission distance increases. For this reason, a bidirectional optical communication device that performs full-duplex optical communication using one optical fiber has been proposed.

In such an optical communication device, since transmission and reception are performed by the same optical fiber, it is important to prevent interference between transmission light and reception light. The cause of the interference of the transmitted light with the received light is that when the transmitted light is reflected by the end face of the optical fiber when entering the optical fiber (hereinafter referred to as near-end reflection), the transmitted light propagated through the optical fiber is emitted from the optical fiber. In some cases, the light is reflected at the end face of the optical fiber (hereinafter, referred to as far-end reflection), and the light is reflected from the other party's two-way communication device (hereinafter, referred to as partner module reflection).

[0004] As a typical method conventionally proposed, there is a method of separating transmission and reception light using a polarization separation element as disclosed in Japanese Patent Application Laid-Open No. 10-153720. This example will be described with reference to FIG.

In FIG. 5, a transmission light 113 emitted from a laser diode 104 is converted into an S-polarized light by a prism 1.
The light is incident on the polarization reflection film 110 on the slope portion 08. Most of the transmission light 113 is reflected by the polarization reflection film 110, condensed by the lens 106, and coupled to the optical fiber 102. On the other hand, the received light 115 emitted from the optical fiber 102 is condensed by the lens 8 and enters the polarization reflection film 110. About half of the received light 115 emitted from the multimode optical fiber 102 is the polarized light reflecting film 110.
And the other half is transmitted and coupled to the light receiving element 105. Since the transmission light 113 reflected by the optical fiber 2 is S-polarized, almost all of the light is reflected by the polarization reflection film 110,
Without coupling to the light receiving element 105, interference due to near-end reflection can be prevented.

Further, as disclosed in Japanese Patent Application Laid-Open No. 11-237535, there is a method in which the angle of the transmitted light is adjusted so that the reflected light of the transmitted light does not enter the light receiving surface. This example will be described with reference to FIG.

In FIG. 6, a transmission light 213 emitted from a light emitting element 204 is condensed by a lens 206, converted into an optical path by a rising mirror 208, and is incident on an optical fiber 202. Received light 215 emitted from the optical fiber is coupled to a light receiving surface 217 of a light receiving element 205 arranged to face the optical fiber 202. Transmit light 21
3 is incident on the optical fiber 202 along a direction different from the direction in which the received light 215 exits from the optical fiber 202. Therefore, the reflected light 2 reflected by the optical fiber 202
Reference numeral 14 irradiates a portion other than the light receiving surface 217 of the light receiving element 205 to prevent interference due to near-end reflection.

[0008]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. H10-1537
In the method disclosed in Japanese Patent Application Publication No. 20-200, since about half of the received light is reflected by the polarization reflection film 110, a reception loss of about 3 dB occurs, and there is a problem that light cannot be used efficiently. Was. Further, although near-end reflection can be prevented, far-end reflection and the reflection of the other module are not uniform in polarization, so that there is a problem that it is difficult to separate the reflected light from the received light. Furthermore, since polarized light is used, an inexpensive light emitting diode (LE) is used as a light emitting element.
Since D) cannot be used, and an expensive polarization separation film is required, there is a problem that the cost is increased.

In the method disclosed in Japanese Patent Application Laid-Open No. 11-237535, the transmission light 213 is transmitted to the reception light 215.
The transmission light 21
No. 3 has a problem that the incident NA to the optical fiber 202 increases and the coupling efficiency with the optical fiber 202 deteriorates.

An optical fiber coupler having an opening is disclosed in Japanese Utility Model Laid-Open Publication No. 63-26810. This example will be described with reference to FIG.

In FIG. 7, light propagating through an optical fiber 302a is collimated by a rod lens 306a to become parallel light, and a part of the light passes through an opening 309 of the optical branching / coupling element 308 and is condensed by a rod lens 306b. Then, the light is coupled to the optical fiber 302b. Further, the light applied to the portion other than the opening 309 of the optical branching / coupling element 308 is reflected, collected by the rod lens 306c, and coupled to the optical fiber 302c. By changing the diameter of the parallel light and the diameter of the opening 309 of the light branching / coupling element 308, the branching efficiency can be changed.

In this optical fiber coupler, the optical fiber 30
By arranging a transmitting element and a receiving element in place of 2b and 302c, transmission and reception light can be branched and used as a two-way optical communication device. In this case, however, interference between transmission light and reception light can be achieved. Since no preventive measures were taken into account, only half-duplex communication could be performed. That is, only a tilt of the optical fiber 202a or a slight assembly error occurs, and the reflected light from the optical fiber 202a returns to the optical branching / coupling element 208 other than the opening 209 and is coupled to the light receiving element. Further, reflection from the end face of the rod lens 206a also causes interference. Furthermore, with this structure, it was difficult to suppress the far-end reflection and the reflection of the partner module.

The present invention has been made in view of these problems, that is, full-duplex bidirectional communication is possible with a single optical fiber, light transmission and reception are small, and light loss is small. It is possible to prevent interference of transmission light with reception light, and it is possible to couple with a large-diameter optical fiber such as POF with high efficiency. , A two-way optical communication device.

[0014]

According to a first aspect of the present invention, a two-way optical communication apparatus performs transmission and reception by using a single optical fiber having an inclined area at least partially at an end face with respect to an optical axis. In the bidirectional optical communication device, transmitting means for emitting transmission light, irradiating the transmission light to the inclined region in the optical fiber, an opening provided in an area where the reception light is incident and transmitting the transmission light, A light separating unit provided around the opening and having a reflecting unit for reflecting the light received from the optical fiber, and a light receiving unit for receiving the received light reflected by the reflecting unit; The transmission light reflected by the light guide is guided to the outside of the reflection section.

A two-way optical communication device according to a second aspect of the present invention is a two-way optical communication device that performs transmission and reception by using a single optical fiber having an inclined region inclined with respect to an optical axis on at least a part of an end face. Transmitting means for emitting transmission light and irradiating transmission light to an inclined region in the optical fiber; an opening provided in a region where the reception light is incident and transmitting the transmission light; and an opening provided around the opening. A light separating unit having a reflection unit for reflecting the reception light from the optical fiber, a light reception unit for receiving the reception light reflected by the reflection unit, and a light reception unit disposed outside an optical path of the reception light, wherein the inclined region is provided. And a light-shielding unit on which the transmission light reflected by the light-receiving unit is directly incident.

A bidirectional optical communication device according to a third aspect of the present invention is the bidirectional optical communication device according to the first or second aspect, wherein the transmitting means converges the transmission light and makes the transmission light incident on the optical fiber. Wherein the incident position of the transmission light on the optical fiber is shifted from the center of the optical fiber in the direction in which the transmission light is reflected at the end face of the optical fiber.

A bidirectional optical communication device according to a fourth aspect of the present invention is the bidirectional optical communication device according to any one of the first to third aspects, wherein an end face of the optical fiber has a conical shape.

A bidirectional optical communication device according to a fifth aspect of the present invention is the bidirectional optical communication device according to the fourth aspect, wherein the transmission light from the transmission means converges so as to be focused at the opening. It is characterized by having.

A bidirectional optical communication device according to a sixth aspect of the present invention is the bidirectional optical communication device according to any one of the first to fifth aspects, wherein an angle α between a perpendicular to the optical axis of the optical fiber and the inclined region is formed. ,
The numerical aperture NAf of the optical fiber, the core refractive index n1, the angle β between the optical axis of the transmission light and the optical axis of the optical fiber, and the numerical aperture NAb of the transmission light are given by: arksin [NAf−n1 × sin (α)] + α <2x
[α + β-arksin (NAb)].

According to a seventh aspect of the present invention, there is provided a bidirectional optical communication device according to any one of the first to sixth aspects, wherein the optical fiber transmits and receives light to and from the bidirectional optical communication device. , Is provided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment according to the present invention will be described with reference to FIGS.

FIG. 1 is a schematic diagram showing the configuration of a two-way optical communication device. The bidirectional optical communication device 3 is connected to an optical fiber 2 for bidirectionally transmitting modulated light suitable for transmission based on a data signal to be transmitted, and to both ends of the optical fiber 2 so as to be optically coupled. And the two-way communicators 1 described above.

FIG. 2 is a schematic sectional view illustrating a two-way communication device according to the first embodiment of the present invention. The bidirectional communication device 1 includes a light emitting element 4 for generating modulated light based on a data signal, a light receiving element (light receiving unit) 5 for receiving modulated light from the optical fiber 2 and generating a data signal, and a light emitting element. The transmission lens 6 includes a transmission lens 6 for converting the transmission light from the (transmission means) 4 into an NA, and a light separation element (light separation means) 8 having an optical opening 9 formed in a part thereof.

First, the main components in FIG. 2 will be specifically described.

The optical fiber 2 is preferably a multi-mode optical fiber such as a POF. The POF has a core made of a plastic having excellent light transmittance, such as PMMA (PolymethylMethaAcrylate) or polycarbonate, and a clad made of a plastic having a lower refractive index than the core. In such an optical fiber 2, the diameter of the core is from about 200 μm to about 1 mm as compared with the quartz optical fiber.
Therefore, it is easy to adjust the coupling with the two-way optical communication device 1, and the inexpensive two-way optical communication device 3 can be obtained.

A PCF having a core made of quartz glass and a clad made of a polymer may be used. PC
F is more expensive than POF, but is characterized by small transmission loss and a wide transmission band. Therefore, PC
By using F as the transmission medium, it is possible to obtain the bidirectional optical communication device 3 capable of performing communication over a long distance and communication at a higher speed.

The light emitting element 4 is composed of a semiconductor laser, a light emitting diode (LED) or the like. The wavelength of the light emitting element 4 is a wavelength at which the transmission loss of the optical fiber 2 used is small,
It is preferably inexpensive. For example, optical fiber 2
When a POF is used, a semiconductor laser having a wavelength of 650 nm, which has a mass production effect for a DVD or the like, can be used. In addition, a monitor photodiode 12 is disposed at the rear of the light emitting element 4 so that the light amount of the light emitting element 4 is kept constant.

As the light receiving element 5, a photodiode having high sensitivity in the wavelength region of the light emitting element 4 by converting the intensity of the received modulated light into an electric signal, for example, a PIN photodiode made of silicon, An avalanche photodiode or the like is used. The light receiving surface 17 of the light receiving element 5 is formed of, for example, silicon nitride to a thickness of about 0.1 μm to prevent reflection of the received light 15 and improve light receiving efficiency. In addition, the anti-reflection film 16 is formed in a portion other than the light receiving surface 17, for example, from a material having a high light absorption rate and a low reflectance in a wavelength region to be used, such as a black colored resist. Not all of the received light 15 is incident on the light receiving surface 17, and a part of the received light 15 is incident on a portion other than the light receiving surface 17 and is reflected.
It causes reflection of the other module. Therefore, by forming the anti-reflection film 16 also on the portion other than the light receiving surface 17 of the light receiving element 5, it is possible to more reliably suppress the reflection of the partner module.

The light separating element 8 is formed on a substrate 11 (which may be made of a material other than plastic such as glass) made of plastic such as PMMA or polycarbonate by injection molding or the like. A reflective surface (reflective portion) 10 formed of a metal material is used. The light separating element 8 has a curved surface on the reflection surface 10 side, and has an opening 9. The opening 9 here refers to an opening in a surface obtained by extending the above-mentioned reflecting surface 10.

The portion of the substrate 11 immediately below the opening 9 is a hollow portion.
A ball lens as the transmission lens 6 is attached. By attaching the transmission lens 6 to the hollow portion in this manner, the alignment of the optical axis of the transmission light 13 can be facilitated.

A light shielding member (light shielding means) 18 is fixed to the light separating element 8, and the light receiving element 5 is provided on the light shielding member 18.

Next, the operation of the bidirectional optical communication device of this configuration will be described.

Transmission light 13 generated by light emitting element 4
Radiate radially according to the radiation angle of the light emitting element 4. Thereafter, the light is converted into an arbitrary numerical aperture NAb by the transmission lens 6 and condensed, passes through the opening 9 of the light separating element 8, and is coupled to the optical fiber 2.

On the other hand, the received light 15 propagating through the optical fiber 2 diverges radially according to the numerical aperture NAf of the optical fiber 2. The light is substantially totally reflected by the curved reflecting surface 10 of the light separating element 8, condensed, and coupled to the light receiving element 5. As described above, by forming the light separating element 8 as a curved surface, a receiving lens becomes unnecessary, and the cost is reduced.
A bidirectional optical communication device 1 that can be easily assembled can be obtained. The curved surface of the light separating element 8 is a spheroid having a focus near the light receiving element 5 and the end face of the optical fiber 2, so that the received light 15 emitted from the optical fiber 2 is efficiently coupled to the light receiving element 7. It becomes possible.

The transmission light (reflected transmission light) 14 reflected at the end face of the optical fiber 2 is reflected outside the reflection surface 10 of the light separating element 8 and is not coupled to the light receiving element 5. Specifically, the reflected transmission light 14 is incident on the end face of the light blocking member 18 and is reflected on the side opposite to the reflection surface 10. Here, since the light blocking member 18 on which the reflected transmission light 14 is incident is disposed outside the optical path of the reception light 15, the light receiving amount is not reduced by the light blocking member 18 and the light receiving member 15 is efficient.

The end face of the optical fiber 2 is processed to an inclination angle of about 10 ° (α in the figure). That is, in FIG. 2, the end face extends to the front of the two-way communication device on the right side (A direction side), and the end face remains on the back side of the two-way communication device on the left side (B direction side). Such an optical fiber 2
For example, when POF is used, processing and manufacturing can be easily performed by inclining the end face and pressing it against a hot plate to melt. By tilting the end face of the optical fiber 2, the reflected transmission light 14 reflected at the end face of the optical fiber 2 is reflected in the direction B in FIG. 2, and the reception light 15 is refracted in the opposite direction (direction A) and emitted. The reflected transmission light 14 can be easily reflected outside the reception light 15. Therefore,
Coupling of the reflected transmission light 14 to the light receiving element 5 can be suppressed, and interference due to near-end reflection can be prevented.

If the end face of the optical fiber 2 is inclined, the light reflected at the far end face can be reduced.
Interference due to far-end reflection can be reduced. When the optical fiber 2 is inclined, the transmission light 13 is refracted when entering the optical fiber 2. Therefore, the coupling efficiency can be improved by inclining the transmission light 13 with respect to the optical axis of the optical fiber 2 so as to be parallel to the optical axis of the optical fiber 2 after refraction.

Further, it is preferable that the transmission light 13 is made incident on the side where the transmission light 13 is reflected from the center of the optical fiber 2, that is, on the B direction side (the side whose end face is deep). By doing so, the reflected transmission light 14 reflected in the B direction side is received light 15
From the optical path of the light source.

Next, conditions for preventing the reflected transmission light 14 reflected by the optical fiber 2 from being coupled to the light receiving element 5 will be described with reference to FIG.

In order to prevent the reflected light 14 from interfering with the received light 15, the divergence angle (θ 1 in the figure) of the received light 15 emitted from the optical fiber 2 is set to the divergence angle of the reflected transmitted light 14 (θ in the figure).
2) It needs to be smaller. The spread angle θ1 of the received light 15 is determined by the numerical aperture NAf of the optical fiber 2, the inclination angle α, and the core refractive index n1. The spread angle θ1 in the B direction (left direction) in FIG. 3 is as follows: θ1 = arksin {NAf−n1 × sin (α)} +
α.

On the other hand, the spread angle θ2 of the reflected transmission light 14 is
Numerical aperture NAb of transmission light 13, transmission light 13 and optical fiber 2
And the inclination angle α of the optical fiber 2. The transmission light 13 is incident such that the reflected transmission light 14 is reflected in the obtuse angle direction (left side in the figure) of the optical fiber 2. The divergence angle of the reflected transmission light 14 in the obtuse angle direction of the optical fiber 2 is θ2 which is the minimum, and θ2 = 2 {α + β-arksin (NAb)}.

Therefore, by determining each parameter so that θ1 <θ2, the reflected light 14 can be converted to the received light 15
Can be separated. Note that the above formula is calculated assuming that the refractive index outside the optical fiber 2 is 1.

When the transmission light 13 is incident on the optical fiber 2, it is refracted by the inclination angle α and enters.
The angle β between the optical fiber 3 and the optical axis of the optical fiber 2 is set to β = arksin (NAf) −θ1, so that the optical fiber 2 becomes parallel to the optical axis of the optical fiber 2 after being incident on the optical fiber 2, 2 can be improved in efficiency.

Next, the loss due to transmission / reception separation by the optical separation element 8 will be described.

After exiting the optical fiber 2, the received light 15 spreads according to the numerical aperture NAf of the optical fiber 2. Optical fiber 2
Is Rf, at the position of the light separating element 8 at a distance L from the optical fiber 2, the received light 15
× (Rf + L × NAf). Then, since the area corresponding to the area of the opening 9 of the light separating element 8 is not reflected, the light is not coupled to the light receiving element 5 and is lost. That is, the loss can be reduced by increasing the distance L and reducing the area of the opening 9. For example, the diameter of the optical fiber 2 is 1 mm, the numerical aperture NAf = 0.3, the distance L between the optical fiber 2 and the light separating element 8 is 1.5 mm, and the opening 9 is φ0.3 m.
Assuming m, the loss is about 0.1 dB.

On the other hand, since the transmitted light passes through the opening 9,
No separation loss occurs. Therefore, it is possible to greatly reduce the separation loss as compared with the reception separation loss of 3 dB in the method using the polarization reflection film. Also, since the aperture 9 is located at the position where the reception light 15 is incident, that is, within the numerical aperture NAf of the optical fiber 2, the transmission light 13 transmits the numerical aperture NAf of the optical fiber 2.
The light can be incident with the following numerical aperture NAb, and the coupling efficiency of the transmission light 13 to the optical fiber 2 can be improved.

As described above, by using the two-way communication device 1 shown in the first embodiment, the near-end reflection, the far-end reflection, and the reflection of the partner module are small, and the entire optical fiber 2 is used. Duplex two-way optical communication becomes possible. Further, the reception light 15 and the reflection light 14 are transmitted through the small-diameter opening 9.
, Separation with low loss becomes possible.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. However, in the second embodiment, members having the same functions as those described in the first embodiment are given the same member numbers as in the first embodiment, and the description thereof is omitted. Was.

In this configuration, the end face of the optical fiber 2 has a conical shape. The light receiving element 5 is provided on a U-shaped light shielding member 18 having an opening through which received light passes, and the receiving lens 7 is provided in a region surrounded by the light shielding member.

The transmission light 13 is transmitted through the transmission lens 6 and has a numerical aperture NA.
b, passes through the opening 9 of the light separating element 8, and
The light enters the center of the end face of the optical fiber 2 in parallel with the optical axis, and is coupled to the optical fiber 2. On the other hand, the received light 15 that has propagated through the optical fiber 2 is reflected by the light separating element 8, condensed by the receiving lens 7, and enters a U-shaped light blocking member 18 having an opening through which the received light passes. It is coupled to a certain light receiving element 5. The transmission light 1 at the end face of the optical fiber 2
The reflected transmission light 3 is reflected outside the reflection surface 10 of the light separating element 8 and is not coupled to the light receiving element 5. Specifically, the light enters the outer wall of the light blocking member 18 outside the optical path of the reception light 15 and does not enter the light blocking member 18. Thus, the light shielding member 1 outside the optical path of the reception light 15
8 so that the reflected transmission light 14 is incident on it.
The received light 15 is not blocked by the light blocking member 18,
It is efficient.

The end face of the optical fiber 2 is formed in a conical shape with an inclination angle of about 10 ° (α in the figure). By making the end face of the optical fiber 2 conical, it is possible to reduce the reflected light at the far end face of the optical fiber 2 and to reduce the interference caused by the far end reflection. Further, since the conical shape is symmetrical with respect to the optical axis of the optical fiber 2, there is no need to worry about the connection direction with the bidirectional optical communication device 1.

It is preferable that the transmission light 13 is condensed by the transmission lens 6 so as to be focused on the opening 9. By setting the position of the opening 9 as the focal point, the area of the opening 9 can be reduced, and the reception loss can be reduced.

Also, as shown in the first embodiment, arksin {NAf-n1 × sin (α)} + α <2
By determining each parameter such that {α + β-arksin (NAb)}, near-end reflection can be more reliably prevented. Further, by covering the receiving lens 7 and the light receiving element 5 with the light shielding member 18, it is possible to prevent interference due to stray light.

As described above, by using the two-way communication device 1 shown in the second embodiment, it is possible to suppress the far-end reflection, the near-end reflection, and the reflection of the partner module, thereby improving the coupling efficiency. The optical communication device 3 can be obtained.

In the above embodiment, an example was described in which the optical fiber used was such that the entire end face was inclined and the end face was conical. However, the present invention is not limited to this, and the present invention is not limited to this. At least one portion may be inclined. In this case, it is desirable that the transmission light be incident on the inclined portion.

Further, in the above-described embodiment, for the light beams such as the transmission light, the reception light, and the reflected transmission light, a portion having an intensity of 1 / e ² or more of the maximum intensity on a plane perpendicular to the optical axis of each light beam. Shall say.

The configuration shown in the present embodiment is an example, and it is needless to say that the same effect can be obtained by partially changing the configuration.

[0058]

According to the present invention, the transmission light reflected by the optical fiber is separated from the reception light and guided to the outside of the reflection surface of the light separating element, so that interference due to near-end reflection can be prevented. In addition, there is no transmission light separation loss, and the reception light separation loss can be reduced. Also, interference due to far-end reflection can be prevented.

If the end face of the optical fiber has a conical shape, even if the transmission light is made incident on the center of the optical fiber, the reflected light is reflected to the outer peripheral portion. Fluctuations are reduced.

Further, the angle α between the perpendicular of the optical axis of the optical fiber and the inclination or conical shape of the end face of the optical fiber, the numerical aperture NAf of the optical fiber, the core refractive index n1, the optical axis of the transmission light and the optical axis of the optical fiber And the numerical aperture NAb of the transmitted light is given by: arcsin {(NAf−n1 · sin (α)} + α <
If the relationship of 2 {α + β-arksin (NAb)} is satisfied, the reflected light spreads more than the received light.
Near-end reflection can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the configuration of a two-way communication device according to the present invention.

FIG. 2 is a schematic diagram illustrating a two-way communication device according to the first embodiment.

FIG. 3 is a schematic diagram illustrating a near-end reflection prevention method of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration of a two-way communication device according to a second embodiment.

FIG. 5 is an explanatory diagram showing a configuration of a conventional optical communication device.

FIG. 6 is an explanatory diagram showing a configuration of a conventional optical communication device.

FIG. 7 is an explanatory diagram showing a configuration of a conventional optical communication device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 bidirectional optical communication device 2 optical fiber 3 bidirectional optical communication device 4 transmitting element 5 receiving element 6 transmitting lens 7 receiving lens 8 light separating element 9 transmitting area 10 reflecting surface 11 substrate 12 monitor photodiode 13 transmitting light 14 reflected light 15 Received light 16 Antireflection film 17 Light receiving surface 18 Light shielding member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Tamura 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yukio Kurata 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F term in reference (reference) 2H037 AA01 BA03 BA12 CA38 DA03 DA04 DA05 5K002 AA05 AA07 BA21 BA31 DA04 DA09 DA42 FA01 GA06

Claims (7)

[Claims] 1. A bidirectional optical communication device for performing transmission and reception using one optical fiber having an inclined area inclined with respect to an optical axis on at least a part of an end face. Transmitting means for irradiating the inclined area with transmission light, an opening provided in an area where the reception light is incident, and transmitting the transmission light, and receiving light from the optical fiber provided around the opening. A light separating unit having a reflecting unit that reflects light; and a light receiving unit that receives the received light reflected by the reflecting unit. The transmitting light reflected by the inclined region is provided outside the reflecting unit. A two-way optical communication device characterized by being guided. 2. A two-way optical communication device for performing transmission and reception using one optical fiber having an inclined region inclined with respect to an optical axis on at least a part of an end face. Transmitting means for irradiating the inclined area with the transmission light, an opening provided in the area where the reception light is incident and transmitting the transmission light, and reflecting the reception light from the optical fiber provided around the opening. A light separating unit having a reflecting unit that receives the light reflected by the reflecting unit; a light receiving unit that receives the received light reflected by the reflecting unit; A two-way optical communication device, comprising: 3. The two-way optical communication device according to claim 1, wherein the transmission unit includes a converging unit that converges the transmission light and makes the transmission light incident on the optical fiber. Wherein the incident position of the optical fiber is shifted from the center of the optical fiber in a direction in which the transmission light is reflected at an end face of the optical fiber. 4. The two-way optical communication device according to claim 1, wherein an end face of said optical fiber has a conical shape. 5. The two-way optical communication device according to claim 4, further comprising a convergence unit that converges the transmission light from the transmission unit so that the transmission light is focused on the opening. Optical communication device. 6. The bidirectional optical communication device according to claim 1, wherein an angle α between a perpendicular to the optical axis of the optical fiber and the inclined region, and a numerical aperture NAf of the optical fiber. , Core refractive index n1,
The angle β between the optical axis of the transmission light and the optical axis of the optical fiber, and the numerical aperture NAb of the transmission light are: arksin [NAf−n1 × sin (α)] + α <2 ×
A bidirectional optical communication device characterized by satisfying [α + β-arksin (NAb)]. 7. A bidirectional optical communication device according to claim 1, comprising: the optical fiber for transmitting and receiving light to and from the bidirectional optical communication device. Bidirectional optical communication device.