JP2002122757A - Method and device for single-core bidirectional optical communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize low cost for single-core bidirectional communication by omitting a beam splitter, and to enhance optical coupling efficiency of optical fibers in transmitting and receiving light. SOLUTION: In the single-core bidirectional optical communication, in which a transmitter 30 and a receiver 40 are arranged near each of both ends of a single optical fiber, one of the transmission and reception at one end of the optical fiber 2 is performed via the end face of the optical fiber, while the other is carried out via a notched part 20 that has a reflection area and installed on the peripheral face of the optical fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for single-core bidirectional communication in which optical signals are bidirectionally transmitted and received using a single optical fiber. More specifically, home communication, communication between electronic devices, LAN (L
The present invention relates to a method and apparatus for single-core two-way optical communication used in an Ocal Area Network or the like.

[0002]

2. Description of the Related Art In the field of single-core bidirectional optical communication, conventionally, it is necessary to prevent near-end reflected return light generated by using a single transmission line from entering a light receiving element (PD) as noise. The mainstream is to separate the polarization inherent in the reflected light of the transmitted light.

As one example, a polarizing beam splitter
Japanese Patent Application Laid-Open Nos. 4-96437 and 10-153720 disclose a method of separating the reflected return light of the transmitted light from the received light using (PBS). Figure 26
Each method will be described with reference to FIG. 27 and FIG.

[0004] In the technique disclosed in FIG.
ED, 102 is PD, 103, 104 are lenses, 105
Is a PBS, 106, 107 and 108 are apertures, and 109 is an optical fiber. The light emitting point of the LED 101 is the lens 10
The optical fiber 109 is disposed at the focal position of the lens 104 at the focal position 3.

[0005] The received light from the optical fiber 109 becomes almost parallel light 111 by the lens 104. Almost parallel light 11
Among the light waves that have become 1, the P wave is reflected by the PBS 105 and received by the PD 102.

The transmission light from the LED 101 is transmitted to the lens 10
3 makes it almost parallel light 110. Among the light waves that have become substantially parallel light 110, the P wave is reflected by the PBS 105 and does not pass through the PBS 105. The S wave of the parallel light 110 passes through the PBS 105, is condensed by the lens 104, and enters the optical fiber 109. 4% of the light collected on the end face of the optical fiber 109 is reflected, and
To reach the PBS 105.

The rotation of the polarization plane does not occur in the reflection at the end face of the optical fiber and the transmission through the lens. Therefore, the reflected return light does not enter the PD 102 because it passes through the PBS 105. The diaphragms 106, 107, and 108 are provided to cut a component that is not parallel light and is generated due to lens aberration or the like.

The technology disclosed in FIG. 27 is similar to the technology shown in FIG. 26, and is an example of a conventional technology using the PBS 205. 201 is the Si on which the PD is formed
A substrate 202, a heat sink of a semiconductor laser (LD),
Numeral 03 denotes an LD, numeral 204 denotes a PD, numeral 205 denotes a prism having a base of a PBS 206, numeral 206 denotes a PBS, numeral 207 denotes a package, numeral 208 denotes a lens, numeral 209 denotes an optical fiber socket and connector, and numeral 210 denotes an optical fiber. Unlike the previous example, the PBS 206 in this example transmits a P-wave and
Designed to reflect waves.

The transmission light from the LD 203 has an S-polarization characteristic. Most of the light is reflected by the PBS 206, the optical path is changed, and the NA is converted by the lens 208, and then enters the optical fiber 210. On the other hand, the received light from the optical fiber 210 is collected by the lens
Then, only the P-polarized light component is transmitted and enters the PD 204. The near-end reflected return light reflected on the end face of the optical fiber 210 maintains the S-polarized component because the rotation of the polarization plane does not occur in the reflection at the end face of the optical fiber and the transmission through the lens. It does not reach the PD 204.

[0010]

However, the system using the PBS as in the conventional example has a problem that the cost of the entire optical system increases because the PBS itself is expensive, and there is a problem that one polarization of the received light is increased. There is a disadvantage that the signal itself is reduced to about half because the component is cut. Further, since the transmitting section and the receiving section must be arranged on the end face of the optical fiber having a maximum diameter of 1 mm, there is a problem of electric interference other than light and a problem that a complicated optical system is required.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to effectively solve the above-mentioned problems of the prior art, and provides an optical communication method and apparatus having the following features. Is what you do.

According to the optical communication method of the present invention, in one-core bidirectional optical communication performed by arranging a transmitting unit and a receiving unit near both ends of one optical fiber, one of transmission and reception at one end of the optical fiber is performed. Is performed through an end face of the optical fiber, and the other is performed through a notch having a reflection surface provided on a peripheral surface of the optical fiber.

A communication device according to the present invention is a communication device provided at one end of an optical fiber in the single-core bidirectional optical communication. In this device, a notch for optical coupling having a reflection surface is provided on a peripheral surface near one end surface of the optical fiber. The one end surface is employed as an optical coupling unit for performing either one of transmission and reception of an optical signal, and the notch is employed as an optical coupling unit for performing the other of transmission and reception.

According to the present invention, single-core bidirectional communication can be performed without using an expensive beam splitter, so that cost can be reduced. Also, in the conventional example using the beam splitter, the respective light amounts of the transmitted and received light are cut by about 50%, but in the present invention,
By adjusting the depth of the notch, optical coupling with higher efficiency than before can be achieved.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. (1) First Embodiment (FIGS. 1 to 4) FIG. 1 is a schematic diagram showing a configuration of a bidirectional communication link according to the first embodiment. In such a bidirectional communication link, an optical fiber 2 for bidirectionally transmitting modulated light suitable for transmission based on a data signal to be transmitted is used, and optical fibers 2 are optically coupled to both ends of the optical fiber 2. , Two bidirectional communication devices 1 are connected.

FIG. 2 shows a schematic sectional structure of the two-way communication device 1, and FIG. 3 shows an enlarged view in a circle of FIG.

The two-way communication device 1 includes a light emitting element (semiconductor laser) 30 that generates modulated light based on a data signal, and a light receiving element 40 that receives modulated light from the optical fiber 2 and generates a data signal. Have. The output of the light emitting element 30 is monitored by a monitor photodiode (not shown) and is controlled to a constant output. The light-emitting element 30 and the light-receiving element 40 may be mounted on a common pedestal, but if electrical interference is a problem, a shield can be provided and separated as in the sixth embodiment described later. It is.

Generally, in a single-core bidirectional optical communication device, it is necessary to provide a light emitting element and a light receiving element in the vicinity of the end face of one optical fiber. However, in the present invention, one of transmission and reception is performed through the cutout 20 provided on the peripheral surface of the optical fiber, so that the light emitting element and the light receiving element can be arranged at a relatively large distance. Although not shown, the light-emitting element 30 and the light-receiving element 40 can be separately protected from the surrounding atmosphere by a cover glass.

In FIG. 2, on the peripheral surface of the optical fiber 2,
A notch 20 for optical coupling is provided. Notch 20,
It includes an inclined surface 20a inclined at an angle of 45 degrees with respect to the optical axis of the optical fiber 2, and a vertical surface 20b orthogonal to the optical axis. On the inclined surface 20a, a reflection film 21 functioning as an optical path conversion mirror for transmitting light or receiving light is formed. This reflective film 21
Is formed using aluminum or the like.

The end of the optical fiber 2 is a ferrule (base).
By 3, fitting and positioning are performed with respect to the receptacle 10. The ferrule 3 is provided with a key 4 for preventing rotation of the optical fiber 2 with respect to the optical axis. The key 4 engages with a fitting groove 11 formed on the inner surface of the receptacle 10.

In the ferrule 3 and the receptacle 10,
Side openings 3a and 10a are formed, respectively, and light from the light emitting element 30 passes through these side openings and reaches the cutout portion 20. In FIG. 2, reference numeral 31 denotes transmission light, and 41 denotes reception light. The optical system 32 detects the incident light N of the transmission light 31
This is for converting A, and may be omitted as described later (see FIG. 5). Further, on the light receiving element 40 side, for example, an optical system for condensing light may be separately provided. In this embodiment, the light emitting element 30 is arranged on the peripheral surface side of the optical fiber 2 and the light receiving element 40 is arranged on the end surface side of the optical fiber 2. The arrangement with the light receiving element 40 may be exchanged.

The principle of the present invention will be described. Optical fiber 2
Means that the refractive index of the core is 1.5 and the refractive index of the cladding is 1.4
15. Assume that it is an SI plastic optical fiber (POF) having a structure NA of 0.5 and a diameter of 1 mm.

Usually, the light beam coupled to this optical fiber is
If the light does not enter the end face of the optical fiber at an angle of 30 ° or less with respect to the optical axis of the optical fiber, the optical fiber 2 is not optically coupled. The propagation angle inside the optical fiber is about 20 with respect to the optical fiber optical axis.
゜. When transmitting light to the optical fiber 2 from the peripheral surface of the fiber, if light rays entering into the optical fiber from the peripheral surface of the optical fiber are not limited to the optical axis but parallel, the angle with respect to the optical axis inside the optical fiber is considered. Is about 50 ° and does not propagate. Therefore, when the light is incident from the peripheral surface, it is necessary to reflect the light after entering the core of the optical fiber and convert the angle to about 20 ° or less with respect to the optical axis of the optical fiber. Notch 20 is provided for this purpose. FIG. 2 illustrates only light that is incident perpendicularly to the optical axis of the optical fiber.
The incident light need not be perpendicular to the optical axis if it falls within (about 20 °).

FIG. 4 is a graph showing the relationship between the maximum incident angle on the inclined surface 20a required for optical coupling with an optical fiber and the structure NA of the POF. This graph shows the slope of the notch 20
In this case, the inclination of 20a is 45 ° and the vertical plane 20b is perpendicular to the optical axis of the optical fiber. When the structure NA is 0.5 and the incident angle on the inclined surface 20a is 30 ° or less,
Optical coupling to the optical fiber 2 becomes possible. Slope 20a
When the inclination of the light beam is different, the allowable incident angle changes according to Snell's law, so that the transmission light 31
In this case, the light may be incident at an angle within ± 30 ° of the vertical.

The advantages of the present invention will be described. Optical fiber 2
Notch 20 of depth 0.3
mm, the cross-sectional area other than the notch 20 can be used for reception. The cross-sectional area ratio can be easily calculated, and about 75% of the cross-sectional area can be used for reception. In contrast, in the case of using polarized light as in the prior art,
Only about 50% of the cross-sectional area can be used for reception, and the merit of the present invention is clear in terms of reception efficiency.

Further, in the present invention, since the light emitting element 30 (transmitting section) and the light receiving element 40 (receiving section) can be arranged relatively far apart, the degree of freedom of the transmission / reception optical system layout is increased. When used for full-duplex communication, transmission light 31
It is necessary to prevent the light from returning to the light receiving element 40. The configuration shown in FIG. 2 in which the light emitting element 30 is provided on the other end side of the optical fiber 2 rather than the light receiving element 40 is suitable for this purpose. further,
As will be described later with reference to FIGS. 19 and 20, it becomes possible to cut off the stray light component by using an opening or a light absorbing member provided in the ferrule near the transmitting section. Further, even if the stray light enters the optical fiber 2, the fiber enters the non-propagation mode. Therefore, there is an advantage that light incident to a part other than the mirror constituted by the reflection film 21 hardly reaches the light receiving element 40.

(2) Second Embodiment (FIG. 5) In the first embodiment, the inclined surface 20a of the notch 20
In addition, a flat reflection film 21 as an optical path changing mirror is disposed, but in the second embodiment, a concave curved surface 20c is employed instead of the inclined surface 20a. Accordingly, the reflection surface 21c is also formed of a curved surface. When such a curved reflecting surface is employed, the optical system 32 as shown in FIGS.
A conversion can be performed.

In order to achieve good optical coupling, it is necessary to consider the arrangement of the light source 30 with respect to the ferrule 3 and the like.
In FIG. 5, the radius of curvature of the reflecting surface 21c is 1.2 mm, the radiation angle from the light emitting element 30 is 10 ° (that is, the incident NA = sin 10 ° = 0.17), and the light emitting element 30 is an optical fiber. 2 and 0.6 mm apart from the peripheral surface. At this time, the substantial excitation NA can be set to 0.1, which is effective in reducing the propagation loss in the fiber and the mode dispersion. Further, high coupling efficiency can be maintained even for an optical fiber having a low NA.

(3) Third Embodiment (FIG. 6) In the first and second embodiments, the notch 20 is used as the transmitting side. However, as shown in FIG. It is also possible to change the arrangement of the notches so that the cutout portion is on the light receiving side.

If the same optical fiber 2 as in the first embodiment is used, the transmitting section can be made smaller in this case, too.
Assuming that the depth of the cutout portion that is the light receiving portion is 0.7 mm and the depth of the remaining portion that can be used as the transmitting portion is 0.3 mm, the same reception efficiency as in the first embodiment can be obtained. Although the transmission light 31 spreads in the optical fiber 2, the stray light of the transmission light 31 does not enter the light receiving element 40 because the reflection film 21 functions as a shielding plate. However, when the transmission light 31 is reflected by the reflection film 21, the transmission efficiency is reduced by that amount. Therefore, except when the transmission light amount is intentionally reduced, the transmission light 31 is directed to a portion other than the cutout portion in the optical fiber 2 using a lens or the like. Transmit light 31
It is necessary to devise the method of incidence. For this reason, as shown in FIG. 2, the light receiving element 40 is disposed on the end face side of the optical fiber 2 and the light emitting element 30 is disposed near the notch 20 on the peripheral surface.
Is preferably arranged.

(4) Fourth Embodiment (FIGS. 7 to 15) In the first to third embodiments, the light emitting element 30 or the light receiving element 40 is located near the cutout 20 formed on the peripheral surface of the optical fiber 2.
And light is directly emitted or received through the notch 20. On the contrary, in FIG.
The light emitting element 30 is disposed at a position near the peripheral surface of the optical fiber opposite to the cutout portion 20 on the upper side. Also in such a configuration, the arrangement of the light emitting element 30 and the light receiving element 40 may be interchanged.

In this case, a reflective film 21 made of aluminum or the like may be provided as shown in FIG. 7, but total reflection by an interface between quartz or PMMA (acryl), which is a material of the optical fiber, and air is prevented. Since it can be used, the number of components can be reduced by omitting the reflection film as in the example of FIG.

Further, the configurations shown in FIGS. 7 and 8 have an advantage that the light reflected by the notch 20 does not need to further pass through the boundary surface. That is, for example, in the configuration of FIG. 3, the light reflected by the reflection film 21 needs to further pass through the boundary surface (vertical surface 20b), and when passing therethrough, the light is scattered. 7 and 8, the problem of such light scattering does not occur.

FIG. 9 is a graph showing the reflectance of TE mode light and TM mode light at the interface between PMMA and air. The incident angle θ of the light ray with respect to the normal to the reflecting surface (see FIG. 8)
It can be understood that total reflection can be achieved by setting the angle to 40 ° or more. In FIG. 8, the transmission light 31 from the light emitting element 30 actually has a certain radiation angle. For this reason, even when θ in FIG. 8 is 40 ° or more, the light of the portion radiated near the tip of the notch 20 may be less than the total reflection angle (40 °). If that happens,
By adding an optical system or changing the direction of the light emitting element 30, the incident angle may be adjusted to exceed 40 ° on the entire reflecting surface.

The light source is not limited to a semiconductor laser.
It is also possible to employ the LED 35 as shown in FIG. However, when the LED 35 is used, the distribution of the light source intensity becomes a Lambertian distribution, and the coupling efficiency is lower than that in the case of the semiconductor laser. Therefore, it is necessary to take measures such as adopting a condensing optical system. However, when light is projected into the optical fiber from the opposite peripheral surface opposite to the cutout portion 20 as shown in FIGS. 7 and 8, the curvature of the peripheral surface of the optical fiber itself can be used as light collecting means. There are advantages (see Figure 11).
That is, the optical system for NA conversion as shown in FIG. 2 can be omitted, and the number of components can be reduced. For example, in the case where the same optical fiber used in the first embodiment is used, if the light source is arranged at a position 1 mm from the peripheral surface of the fiber, the amount of light having an incident NA of 0.3 is converted into 0.2 and the light is substantially converted to 0.2. Excitation NA can be reduced.

When the semiconductor laser 30 is used as the light source, the radiation angle is relatively small as shown in FIG. 12 as compared with the case of the LED, which is advantageous in terms of transmission coupling efficiency.
For example, in the case of a CLS0765 semiconductor laser manufactured by Sharp Corporation, the emission angle is 30 ° in the ⊥ direction (vertical direction),
// 8 ° in the direction (parallel direction). As shown in FIG.
// If the direction is parallel to the optical fiber end face, most of the emitted light 31 can be coupled to the notch 20 in the // direction. However, in that case, the radiation angle becomes large in the ⊥ direction. In other words, when high transmission coupling efficiency is required, as shown in FIGS. 14 and 15, the ⊥ direction is parallel to the fiber end face so that the lens effect of the optical fiber peripheral surface itself can be used in the ⊥ direction, It is preferable that the direction of the small emission angle // is parallel to the optical axis of the optical fiber. When the distance from the light source to the peripheral surface of the optical fiber is 1 mm, it is possible to spin approximately 80% of the light with the notch having a depth of 0.3 mm.

(5) Fifth Embodiment (FIGS. 16 to 20) In the case of transmission between devices such as a digital video camera using an optical fiber in accordance with the standard such as IEEE1394, the transmission distance is only a few meters, so that it is a light receiving element. This may be a problem because the amount of light incident on the photodiode is too large. If the optical fiber is short, propagation loss does not occur, and almost all of the light from the light emitting element reaches the photodiode.

As a countermeasure in this case, it is possible to reduce the transmission light amount by reducing the light amount itself transmitted from the semiconductor laser, but in the present invention, the notch portion 20 is configured to be shallow as shown in FIG. This reduces the amount of transmitted light. That is, when the notch is made shallow, the area of the inclined surface is correspondingly reduced, and as a result, the amount of transmission light transmitted through the optical fiber 2 is reduced. The same effect can be obtained even if the width is reduced instead of making the notch shallow. In addition,
Since it is necessary to maintain the oscillation state in order to avoid the occurrence of oscillation delay even when the transmission pulse is dark, there is a limit in reducing the light amount of the semiconductor laser in order to obtain a predetermined extinction ratio.

FIG. 17 shows the relationship between the depth of the notch and the transmission light rate. Here, the semiconductor laser spot, which is the light emitting element, is arranged parallel to the minor axis direction optical fiber optical axis direction, and the major axis direction is perpendicular to the optical fiber optical axis direction. 0.6 mm distance
It is the result when it is set to. It can be seen that as the depth of the notch is increased, the transmission light rate increases and the amount of received light increases.

FIG. 18 shows the relationship between the transmission distance and the amount of incident light on the light receiving element when each of the notches has the notch depth shown in FIG. The longer the transmission distance, the greater the loss of light, and thus the less light reaches the light receiving element. Conversely, the upper limit of the maximum amount of light received by the light receiving element is determined by the limitation of the dynamic range of the light receiving element. In this case, 0.7 mW is the upper limit. When the amount of received light varies depending on the transmission distance (length of the optical fiber), the configuration of the optical communication module such as the light receiving element and the light emitting element is changed according to the transmission distance.
Adjusting and changing the depth of the notch in accordance with the transmission distance improves the mass production effect rather than (for example, increasing the laser power). In other words, when connecting the devices as described above, the optical fiber only needs to be several meters long, so it is preferable that the cutout portion of the optical fiber is made shallow. In addition, when the transmission distance is long, an optical communication device that can support various transmission distances can be obtained by making the notch deep.

When the amount of transmitted light is increased or decreased by changing the depth of the notch as described above, the transmission light projected to the peripheral portion other than the notch 20 does not enter the propagation mode, and therefore, is not transmitted into the optical fiber. Causes stray light that is not propagated. A method for preventing such stray light from occurring will be described with reference to FIGS. 19 and 20.

In FIG. 19, an opening 3b is provided on the side of the ferrule 3 around the notch 20. Although not shown, an opening connected to the opening 3b is also provided on the side of the receptacle (see FIG. 2) located outside the ferrule 3. Thereby, the transmission light that is not emitted to the cutout portion 20 and does not propagate in the optical fiber passes through the opening and escapes outside the optical fiber. On the other hand, in FIG. 20, a light absorbing member 39 is arranged on the inner peripheral surface of the ferrule 3 to absorb light that is not radiated to the cutout portion 20. With the configuration shown in FIG. 19 or FIG. 20, it is possible to prevent the light projected around the notch 20 from being irregularly reflected and reaching the light receiving element 40, and as a result, the SN ratio can be improved. 19 and 20, a semiconductor laser is used as the light emitting element 30, but the same applies to a case where an LED is used. Note that the method of adjusting the light amount by changing the depth, width, and the like of the cutout can be adopted even when a light emitting element is provided near the cutout as shown in FIG.

(6) Sixth Embodiment (FIG. 21) In the two-way communication apparatus of the present invention, interference at the time of transmission and reception can be easily prevented not only optically but also electrically. In the case of half-duplex communication where transmission and reception are not performed at the same time, crosstalk between transmission and reception is not a problem,
In full-duplex communication in which transmission and reception are performed simultaneously, it is necessary to prevent interference between the transmitting element and the receiving element, and the circuits associated therewith.

As described in the first embodiment,
In a typical single-core bidirectional optical communication device, the maximum is 1 m
Since it is necessary to provide a transmitting / receiving function near the end face of the optical fiber having only m, it is difficult to arrange the transmitting unit and the receiving unit far apart. However, in the present invention, since the transmitting unit and the receiving unit can be relatively separated from each other, the light emitting element 30 and its package 130, the light receiving element 4
It is easy to separate and arrange 0, its package 140, and each associated circuit. Further, regarding the electromagnetic waves, as shown in FIG. 21, a shield 50 can be provided to prevent mutual interference.

(7) Seventh Embodiment (FIGS. 22 to 25) A method of forming a notch in the peripheral surface of an optical fiber will be described.
As shown in FIG. 22, in the state of the optical fiber, a slit cut is made by a taper cutting blade 61. Reference numeral 60 denotes a rotation axis of the blade 61. If a fine-grained blade is used, a surface having a roughness similar to that of a polished surface can be obtained. This is effective for a quartz fiber in which the melting method described later cannot be adopted.

When the optical fiber is POF, the method of pressing the heater 70 having the projection 71 having a shape corresponding to the cutout 20 is simple as in the case of the end face processing by ordinary hot melt, and the viewpoint of the surface roughness is high. It is also effective from. The specific procedure is as follows. Since ordinary POF is made of PMMA, its softening point is between 74 ° C and 99 ° C. First, the heater 70 is heated to 74 ° C. or higher (FIG. 23). Thereafter, the heater 70 is pressed against the peripheral surface of the optical fiber (FIG. 24). Heater 70
The power is turned off while pressing is pressed, and the heater 70 is separated from the POF after the temperature has sufficiently dropped below 74 ° C. (FIG. 25).
The smaller the heat capacity of the heater, the better.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a bidirectional optical communication link to which the present invention has been applied.

FIG. 2 is a schematic sectional view illustrating an example of the optical communication device of the present invention.

FIG. 3 is an enlarged view showing the inside of a circle of FIG. 2;

FIG. 4 is a graph showing a relationship between a structure NA and an incident angle.

FIG. 5 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 6 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 7 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 8 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 9 is a graph showing a relationship between an incident angle and a reflectance.

FIG. 10 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 11 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 12 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 13 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 14 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 15 is a schematic sectional view of the example of FIG. 14 as viewed from the optical axis direction of the optical fiber.

FIG. 16 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 17 is a graph showing a relationship between a notch depth and a transmission light rate.

FIG. 18 is a graph showing the relationship between the transmission distance and the amount of incident light on the light receiving element when the notch depth is changed.

FIG. 19 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 20 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 21 is a schematic sectional view illustrating another example of the optical communication device of the present invention.

FIG. 22 is a schematic sectional view illustrating an example of the method for manufacturing an optical communication device according to the present invention.

FIG. 23 is a schematic sectional view illustrating a second example of the method for manufacturing an optical communication device according to the present invention.

FIG. 24 is a schematic sectional view illustrating a second example of the method for manufacturing the optical communication device according to the present invention.

FIG. 25 is a schematic sectional view illustrating a second example of the method for manufacturing the optical communication device according to the present invention.

FIG. 26 is an explanatory diagram showing a configuration of a conventional optical communication device.

FIG. 27 is an explanatory diagram illustrating a configuration of a conventional optical communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bidirectional optical communication apparatus 2 Optical fiber 3 Ferrule 4 Key 10 Receptacle 11 Mating groove 20 Notch 21 Reflective film 30 Light emitting element 31 Transmitted light 32 Optical system 35 LED 36 Transmitted light 39 Light absorbing member 40 Light receiving element 41 Received light 50 Electromagnetic Shield 60 Blade rotation axis 61 Blade 70 Heater 71 Projection 130 Transmitter package 140 Transmitter package

Claims (15)

[Claims] In one-core bidirectional optical communication in which a transmitting unit and a receiving unit are respectively arranged near both ends of one optical fiber, one of transmission and reception at one end of the optical fiber is performed via an optical fiber end face. An optical communication method, wherein the other is performed through a notch having a reflection surface provided on a peripheral surface of the optical fiber. 2. The optical communication method according to claim 1, wherein the transmission of the optical signal is performed through the cutout portion, wherein the optical fiber is transmitted from an opposing peripheral surface of the optical fiber opposite to the peripheral surface where the cutout portion is formed. , And project light toward the reflective surface of the notch,
An optical communication method comprising transmitting transmission light toward the other end of an optical fiber by using total reflection on the reflection surface. 3. The optical communication method according to claim 1, wherein transmission of an optical signal is performed through said cutout portion, wherein said optical fiber is transmitted from an opposing peripheral surface opposite to a peripheral surface where said cutout portion is formed. An optical communication method comprising: projecting light toward a reflection surface of a notch to collect light on the reflection surface by using a curvature of a peripheral surface of the optical fiber itself. 4. The optical communication method according to claim 1, wherein a semiconductor laser is employed as a light emitting means of said transmitting section, and an optical signal is transmitted through said notch. Light is projected from the opposite peripheral surface on the opposite side to the reflected surface of the notch, and the major axis of the light emitted from the semiconductor laser is made to coincide with the direction perpendicular to the optical fiber optical axis. Characterized in that the minor axis of the optical fiber coincides with the direction parallel to the optical fiber optical axis,
Optical communication method. 5. The optical communication method according to claim 1, wherein the transmission of the optical signal is performed through the notch, and the light is projected with a radiation area larger than a reflection surface of the notch, so that the light is transmitted through the optical fiber. An optical communication method, characterized in that the amount of transmitted light for transmitting the light is smaller than the amount of emitted light. 6. A communication device provided at one end of an optical fiber in single-core bidirectional optical communication performed by arranging a transmitting unit and a receiving unit near both ends of one optical fiber, respectively. A notch for optical coupling having a reflective surface is provided on a peripheral surface near one end face, and the one end face is employed as an optical coupling section for performing one of transmission and reception of an optical signal, and an optical coupling section for performing the other of transmission and reception. A two-way communication device, characterized in that the notch is employed. 7. The two-way communication device according to claim 6, wherein the reflection surface of the notch is formed by a plane inclined with respect to the optical axis of the optical fiber. 8. The two-way communication according to claim 6, wherein the reflection surface of the cutout is formed as a concave surface inclined toward an end surface of the optical fiber opposite to the one end surface. apparatus. 9. The optical fiber according to claim 6, wherein a transmitting unit or a receiving unit is arranged near an opposing peripheral surface on a side opposite to the peripheral surface where the cutout portion is formed. Communication device. 10. The two-way optical communication device according to claim 6, wherein said transmitting section includes a semiconductor laser as a light emitting means. 11. The two-way communication device according to claim 9, wherein said cutout portion is adopted as a light coupling portion for transmission, and a transmission portion is arranged near said opposed peripheral surface position. A two-way communication device, comprising: an optical path for allowing light from a transmission unit projected onto an inner peripheral surface of an optical fiber to escape to the outside of the optical fiber. 12. The two-way communication device according to claim 9, wherein said cutout portion is adopted as an optical coupling portion for transmission, and a transmission portion is disposed near said opposing peripheral surface position. A bidirectional optical communication device, comprising: a light absorbing member that absorbs light from a transmitting unit projected onto an inner peripheral surface of an optical fiber. 13. A shield provided between the transmitting unit and the receiving unit to prevent mutual interference of electromagnetic waves.
The two-way optical communication device according to claim 6. 14. The optical fiber according to claim 6, wherein said optical fiber is a plastic optical fiber whose plastic core is made of plastic, and said notch is formed on the peripheral surface of said optical fiber by grinding. A two-way communication device as described. 15. A plastic optical fiber having a waveguide core made of plastic as the optical fiber, wherein the notch is formed in a peripheral surface of the optical fiber by heating and melting. 7. The two-way communication device according to 6.