JP2001068737A - Light emitting / receiving device and single-core optical fiber bidirectional communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize optical power loss, reduce the cost and structure, and to improve reliability, by embedding light-emitting means within a light- propagating member, and by propagating light from the light-emitting means to a terminal. SOLUTION: First, light traveling along an optical fiber 8 exits from a terminal 9 and is converged via an exiting lens 19 for continuous propagation through a light-propagating member 13. The propagating light reaches a light-receiving surface 16 of a light-receiving element 12. Then, light exiting from a light- emitting surface 14 of a light-emitting element 11 propagates along the fiber 8 through the lens 19 and the terminal 9 in sequence, for coupling with the element 12 of a light-receiving/emitting module 3 on the opposite side via an optical fiber cable. Even when light from the terminal 9 of the fiber 8 scatters, the lens 19 formed at one end of the member 13 converges the scattered light for further travelling to the element 12, whereby the loss of received light due to the element 11 being embedded within the member 13 can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting / receiving device for performing bidirectional optical communication using one optical fiber,
Further, the present invention relates to a single-core optical fiber bidirectional communication system.

[0002]

2. Description of the Related Art FIG. 7 is disclosed in Japanese Patent Application Laid-Open No. 61-9610 (applicant: NEC Corporation, filing date: June 25, 1984, title of module: optical two-way communication module). FIG. 1 shows a basic configuration diagram of a system in a single-core optical fiber bidirectional communication performed. The system configuration will be described as follows.

[0003] Reference numeral 101 denotes a light emitting / receiving device, which is a light emitting device 102 (light emitting means) for converting an electric signal into an optical signal and a light receiving device 103 for converting an optical signal into an electric signal.
(Light receiving means) and an optical directional coupler or optical demultiplexer 104. On the other hand, reference numeral 105 denotes a light-emitting / light-receiving device.
(Light receiving means) and an optical demultiplexer 108.
These light emitting / receiving devices 101 and 105 are optically connected via one optical fiber 109.

The above publication also discloses a configuration in which the components of the light emitting / receiving device 101 (105) as shown in FIG. 8 are integrated. That is, the light emitting / receiving device 1
01 ′ (105 ′) converts light from the light emitting element 110 (light emitting means) into parallel light by the lens 111, and condenses the light by the lens 113 via the half mirror 112;
14, the light from the optical fiber 114 is reflected by the half mirror 112, collected by the lens 115, and then connected to the light receiving element 116 (light receiving means).

On the other hand, Japanese Patent Application Laid-Open No. 4-315327 (applicant: NEC Corporation, filing date: April 12, 1991)
Japanese Patent Application Laid-Open No. H06-216, entitled "Semiconductor Light Emitting / Receiving Device") discloses a single-core optical fiber bidirectional communication system having a configuration as shown in FIG.

[0006] In the single-core optical fiber bidirectional communication system, A and B indicate light-emitting and light-receiving devices having the same configuration, respectively. Reference numeral 117 indicates a laser diode (light-emitting means), and 118 indicates the laser diode (light-emitting means). A monitor light receiving element of the laser diode 117, 119 is a light receiving element (light receiving means), 120 to 122 are focusing lenses, 123 is a beam splitter, 124 is a rotating element for rotating incident light by 45 °, and 125 is light emission and emission of A and B. The optical fiber which connects between light receiving devices is shown.

In the above configuration, the optical signal from the laser diode 117 on the A side is collimated by the focusing lens 120 and transmitted through the beam splitter 123. Then, after the polarization plane is rotated by 45 ° by the rotation element 124, the light is transmitted to the B side via the focusing lens 122 and the optical fiber 125.

Since the optical signal from the A side is again rotated by 45 ° on the B side by the rotating element 124, the beam splitter 123 is rotated in a state where the polarization plane is rotated by a total of 90 °.
Will be incident. Therefore, the incident signal light is reflected here, and is transmitted through the focusing lens 121 to the light receiving element 11.
9 to be received.

The optical signal from the laser diode 117 on the B side is also received by the light receiving element 119 on the A side.

[0010]

In the above-mentioned prior art, since the light emitting / receiving device is composed of a large number of optical components, the light emitting / receiving device itself and the single-core optical fiber bidirectional device are used. The cost of the communication system (hereinafter abbreviated as a system) cannot be avoided.

[0011] In addition, since many optical components are provided, there has been a concern about the reliability of the light emitting / receiving device and the system.

Further, as can be seen from the arrangement of the various optical components described above (particularly the arrangement of the light emitting means and the light receiving means), it is difficult to reduce the size of the light emitting / receiving apparatus and the light emitting / receiving apparatus and the system itself become large. Had become.

Furthermore, since the light emitting / receiving device uses an optical demultiplexing / combining device, the loss of optical power is large in terms of performance, leading to a reduction in the dynamic range.

It is to be noted that the decrease in the dynamic range described above is caused by
This means that the output margin in consideration of the loss of various optical powers in the entire system is reduced. For example, when the system is mounted on a vehicle such as an automobile, the degree of freedom in design is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a light emitting / receiving device capable of minimizing loss of optical power as well as reducing costs, miniaturizing, and improving reliability. It is an object to provide a two-core optical fiber communication system.

[0016]

According to a first aspect of the present invention, there is provided a light emitting / receiving device for converting an electric signal into an optical signal, and a light emitting means for converting an optical signal into an electric signal. A light-emitting / light-receiving device, comprising: a light-receiving unit, and a light-propagating member that is disposed to face an end of one optical fiber and propagates light from the light-emitting unit and light to the light-receiving unit. Forming a lens protruding toward the terminal at one end of the light propagation member facing the terminal and arranging the light receiving means at the other end with respect to the one end to emit the light to the light receiving means emitted from the terminal. The light is transmitted from the one end to the other end, and the light emitting means is embedded in the light transmitting member so that the light from the light emitting means is transmitted toward the terminal.

According to a second aspect of the present invention, in the light emitting / receiving device according to the first aspect, the area of the light receiving surface of the light receiving unit is larger than the area of the light emitting surface of the light emitting unit. It is characterized by:

According to a third aspect of the present invention, in the light emitting / receiving device according to the first or second aspect, the width of the lens is larger than the diameter of the terminal. I have.

According to a fourth aspect of the present invention, in the light emitting / receiving device according to any one of the first to third aspects, an antireflection film is formed on the lens and / or the terminal. Features.

According to a fifth aspect of the present invention, in the light emitting / receiving device according to any one of the first to fourth aspects, a wavelength selection filter is disposed between the light emitting unit and the light receiving unit. It is characterized by doing.

Claim 6 has been made to solve the above problem.
The single-fiber optical fiber bidirectional communication system according to the present invention is characterized in that the light emitting / receiving device according to any one of claims 1 to 5 is disposed at both ends of a single optical fiber.

According to a seventh aspect of the present invention, there is provided the single-core optical fiber two-way communication system according to the sixth aspect, wherein the single-core optical fiber two-way communication system is mounted on a vehicle such as an automobile. I have.

According to the first aspect of the present invention, by embedding the light emitting means in the light transmitting member, light from the light emitting means propagates through the light transmitting member and enters the terminal of the optical fiber. Further, the light propagating in the optical fiber is incident on one end of the light propagation member, propagates in the light propagation member, and is coupled with the light receiving means provided on the other end. Even if the light emitted from the end of the optical fiber is diffused, the light is focused toward the light receiving means by the lens formed at one end of the light propagation member.

According to the second aspect of the present invention, when the light to the light receiving means passes through the light emitting surface of the light emitting means, the transmission area thereof becomes large.

According to the third aspect of the present invention, even if the light emitted from the end of the optical fiber is diffused, it is collected toward the light receiving means. Further, when light to the light receiving means passes through the light emitting surface of the light emitting means, the transmission area thereof becomes large.

According to the present invention, more light propagating in the optical fiber is incident. Also, more light from the light emitting means enters the end of the optical fiber. Further, the influence of crosstalk is reduced.

According to the fifth aspect of the present invention, it is possible to propagate a plurality of lights having different wavelengths.

According to the sixth aspect of the present invention, the light emitting / receiving device according to any one of the first to fifth aspects is disposed at both ends of one optical fiber. A single-core optical fiber bidirectional communication system having the functions and effects of the light emitting / receiving device is configured.

According to the seventh aspect of the present invention, since the degree of freedom of design is improved and the vehicle is mounted on a vehicle such as an automobile, the wire harness wired in the vehicle in addition to the above-described operation and effect. , Line saving and weight reduction are achieved.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram showing one embodiment of a single-core optical fiber bidirectional communication system of the present invention. 2 is a plan view including a partial cross section of the light emitting and receiving module of FIG. 1, FIG. 3 is a front view including a partial cross section of the light receiving and emitting module of FIG. 1, and FIG. FIG. 4 shows a side view including a cross section.

In FIG. 1, reference numeral 1 denotes a single-core optical fiber bidirectional communication system mounted on a vehicle such as an automobile, and a light emitting / receiving module as a light emitting / receiving device is provided at both ends of an optical fiber cable 2. 3, 3 are arranged.

That is, at both ends of the optical fiber cable 2,
For example, an optical connector 6 composed of a receptacle 4 and an optical plug 5 is provided, respectively, and the light receiving / emitting modules 3, 3 are disposed on the receptacles 4, 4 mounted on a wiring board (not shown), and a single-core optical fiber bidirectional cable is provided. The communication system 1 is configured.

The optical plugs 5, 5 to be fitted to the receptacles 4, 4 on which the light emitting / receiving modules 3, 3 are provided, are connected to the ferrules 7, 7 attached to both ends of the optical fiber cable 2, respectively. It is configured to be held, and when fitted to the receptacles 4, 4, the gap loss between the light receiving and emitting modules 3, 3 is kept to a minimum.

In this embodiment, the light receiving / emitting modules 3 will be described as corresponding to the light emitting / receiving device described in the claims. However, the receptacle 4 or the optical connector 6 is used as the light emitting / receiving device. It can be replaced.

Next, the respective components described above will be described in detail below.

The optical fiber cable 2 is composed of an optical fiber 8 (see FIG. 2, the same applies hereinafter) and a plurality of layers of coating material for coating the optical fiber 8. The ferrules 7, 7 are mounted in a state in which is exposed.

The optical fiber 8 is made of a transparent resin material such as, for example, PMMA (polymethyl methacrylate (methacrylic resin)) (or may be made of glass), and has a terminal 9 (see FIG. 2, hereinafter the same). , An anti-reflection film (not shown, AR coat) is formed. If the optical fiber cable 2 is called an optical fiber, the optical fiber 8 corresponds to a core portion.

The ferrule 7 is formed in a cylindrical shape having a step inside and outside, and an optical fiber 8 is mounted in a small diameter portion 10 thereof. In addition, the terminal 9 of the optical fiber 8 is exposed at the distal end surface of the small diameter portion 10. For example, an adhesive or the like is applied to the inside of the ferrule 7 so that the ferrule 7 does not easily fall off from the end of the optical fiber cable 2.

As shown in FIG. 2 to FIG. 4, the light receiving / emitting module 3 has a light emitting element 11 as a light emitting means, a light receiving element 12 as a light receiving means, and a substantially cylindrical shape made of a transparent resin material. Or a substantially bullet-shaped) light propagation member 1
3 and are arranged to face the terminal 9 of the optical fiber 8 with a slight gap.

The light emitting element 11 is a light emitting diode (LE)
D) or a laser diode (LD), which is embedded in the light propagation member 13 so that its light emitting surface 14 is arranged coaxially with the optical fiber 8. Further, the light emitting element 11
The terminal 15 is connected to a driver circuit for a light emitting element formed on the wiring board (not shown).

The light emitting element 11 is located at one end of the light transmitting member 13, that is, at one end of the light transmitting member 13 facing the terminal 9, and has the directivity of the light emitting element 11 toward the terminal 9 and the light emitting surface 14.
It is buried at a position where the above-mentioned received light loss described later can be sufficiently considered. Therefore, the position is not limited to the position shown in the figure, and it is also possible to bury a reflecting member such as a mirror and direct the reflected light (optical signal, transmitted light) to the terminal 9.

The light emitting element 11 is configured such that the area of the light emitting surface 14 is smaller than the area of the terminal 9 of the optical fiber 8 and sufficiently smaller than the area of the light receiving surface 16 described later. ing.

The light receiving element 12 is, for example, a photodiode (PD), and is disposed such that its light receiving surface 16 is in close contact with the other end of the light propagation member 13. The light receiving element 12 is formed in a substantially disk shape (not limited to this shape) corresponding to the diameter of the light propagation member 13, and the terminal 17 extending therefrom is connected to the terminal 15 of the light emitting element 11.
Similarly to the above, it is connected to a driver circuit for a light receiving element on the wiring board (not shown).

The light receiving element 12 includes a gap between the terminal 9 and one end of the light propagation member 13, a refractive index of a lens 19 described later, and a loss of received light (light (light signal, It is assumed that the area of the light receiving surface 16 is set in consideration of the loss caused by the reception light) by the light emitting element 11. Further, the light to the light receiving element 12 is emitted from the light emitting surface 1.
It is preferable to set the area of the light receiving surface 16 so that the transmission area becomes sufficiently large when the light passes through the upper surface 4. Reference numeral 18 is a base member for the light receiving element 12.

The light propagation member 13 has the same P as that of the optical fiber 8.
It is made of MMA (polymethyl methacrylate (methacrylic resin)) or an equivalent transparent resin material, and the light emitting element 11 is embedded therein as described above. A lens 19 protruding toward the terminal 9 is formed at one end of the light propagation member 13, and the light receiving element 12 is arranged at the other flat end. Furthermore, the diameter of the light propagation member 13 matches the width of the lens 19, and the width is larger than the diameter of the optical fiber 8, that is, the diameter of the terminal 9 (in this embodiment, larger than the diameter of the small diameter portion 10). It is formed so that it becomes. The lens 19 has
An anti-reflection film (not shown, AR coat) is formed.

The detailed description of the receptacle 4, the optical plug 5, and the optical connector 6 will be omitted. A known structure such as an optical connector may be applied and the design thereof may be changed as appropriate so that the light propagation member 13 can be mounted (especially the receptacle 4).

Next, the manufacturing process of the light emitting / receiving module 3 will be described with reference to FIGS.

First, as shown in FIG. 5, the light emitting element 11 is embedded in the light transmitting member 13 by resin molding (injection molding) to form a light emitting element lens assembly 20. And
The light receiving element 12 is attached and fixed to the light emitting element lens assembly 20 together with the base member 18 (see FIG. 6). As described above, the manufacture of the light emitting and receiving module 3 is completed (the light emitting and receiving module 3 can be manufactured by a very simple process).

Next, the operation of the light emitting / receiving module 3 will be described with reference to FIG.

First, the light propagating through the optical fiber 8 to the light receiving element 12 is emitted from the terminal 9, condensed via the lens 19, and propagates through the light propagation member 13. Then, the light travels inside the light propagation member 13 and propagates to the light receiving surface 16.

Next, the light emitting element 1 emitted from the light emitting surface 14
Light from 1 propagates through the optical fiber 8 through the lens 19 and the terminal 9 in this order. And the optical fiber cable 2
(See FIG. 1).

In the above configuration and the like,
In the (single-core optical fiber bidirectional communication system 1), since there is no conventionally used optical component such as a half mirror, the optical fiber 8
There is no possibility that the light amount of the light incident on the halves becomes half.

Further, since the light receiving / emitting module 3 is configured without using the optical demultiplexing / combining device, the output margin can be made wider than before. That is, even when various optical power losses such as the optical power loss due to the optical fiber 8 are considered, the margin at the time of coupling with the light receiving element 12 becomes larger than before.

On the other hand, as can be seen from the arrangement of the light emitting element 11 and the light receiving element 12, the light receiving and emitting module 3 can be said to be compact.

Further, since the structure of the light emitting / receiving module 3 itself is simple, the reliability is improved and the cost is reduced.

On the other hand, the degree of freedom in designing the single-core optical fiber bidirectional communication system 1 is improved by the light emitting / receiving module 3, and the wire harness (not shown) routed in the vehicle is reduced in weight and weight. Can be achieved.

Therefore, from the above, it is possible to minimize the loss of the optical power, reduce the cost, reduce the size, and improve the reliability.

In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the gist of the present invention. That is, a wavelength selection filter may be arranged between the light emitting element 11 and the light receiving element 12 in the light propagation member 13 so as to propagate a plurality of lights having different wavelengths. The anti-reflection film (not shown) is formed in consideration of crosstalk (may not be provided).

[0059]

As described above, according to the first aspect of the present invention, by embedding the light emitting means in the light transmitting member, the light from the light emitting means propagates through the light transmitting member. The light enters the end of the optical fiber. Also, the light that has propagated in the optical fiber enters one end of the light propagation member,
The light propagates through the light propagation member and is coupled to the light receiving means disposed at the other end. Even if the light emitted from the end of the optical fiber is diffused, the light is focused toward the light receiving means by the lens formed at one end of the light propagation member.
This makes it possible to minimize the loss of received light due to the burying of the light emitting means. The light emitting and receiving devices include
For example, since there is no conventionally used optical component such as a half mirror, the amount of light that propagates in the optical fiber and enters the light propagation member does not become half. Further, since the light emitting / receiving device is configured without using the optical demultiplexing / combining device, the output margin can be made wider than before. That is, even when various optical power losses such as a loss of optical power due to a gap between a light propagation member and a terminal of an optical fiber and a loss of optical power due to an optical fiber are taken into consideration, the margin at the time of coupling with the light receiving means is taken into consideration. Becomes larger than before. Therefore, better optical communication can be realized. On the other hand, the arrangement of the light emitting means and the light receiving means makes the light emitting / receiving device more compact than before. That is, since the light emitting means is not provided as a separate member in the direction orthogonal to the axis of the optical fiber with respect to the light propagation member, the size of the light emitting / receiving device can be reduced particularly in the orthogonal direction.
In addition, since the configuration itself is simple, reliability is enhanced and cost is reduced. Therefore, it is possible to provide a light emitting / receiving device capable of minimizing the loss of optical power as well as reducing costs, miniaturizing, and improving reliability.

According to the second aspect of the present invention, since the area of the light receiving surface of the light receiving means is larger than the area of the light emitting surface of the light emitting means, the light to the light receiving means emits light from the light emitting means. When transmitting on a surface, the transmission area increases. Therefore, there is an effect that the loss of the received light on the light emitting surface can be suppressed as much as possible.

According to the third aspect of the present invention, since the width of the lens is made larger than the diameter of the terminal, even if the light emitted from the terminal of the optical fiber is diffused, the light is transmitted to the light receiving means. It is focused toward. Further, when light to the light receiving means passes through the light emitting surface of the light emitting means, the transmission area thereof becomes large. Therefore, even if the light emitted from the end of the optical fiber is diffused, it is not only efficiently collected toward the light receiving means but also received light loss when the light emitting means is close to one end of the light propagation member. This also has the effect of suppressing as much as possible.

According to the present invention, since the antireflection film is formed on the lens and / or the end of the optical fiber, more light propagating in the optical fiber is incident. Further, more light from the light emitting means enters the end face of the optical fiber. Further, the influence of crosstalk is reduced. Therefore, it is possible to reduce the loss of optical power related to the optical fiber and the light propagation member, and to improve the reliability.

According to the fifth aspect of the present invention, since the wavelength selection filter is disposed between the light emitting means and the light receiving means, a plurality of lights having different wavelengths can be propagated. To play.

According to the sixth aspect of the present invention, the light emitting / receiving device according to any one of the first to fifth aspects is disposed at both ends of one optical fiber. There is an effect that a single-core optical fiber bidirectional communication system having the function and effect of the light emitting / receiving device can be configured.

According to the present invention, since the degree of freedom of design is improved and the vehicle is mounted on a vehicle such as an automobile, the wire harness wired in the vehicle in addition to the above-described effects can be obtained. This leads to an effect that the wire can be saved and the weight can be reduced.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of a single-core optical fiber bidirectional communication system according to the present invention.

FIG. 2 is a plan view including a partial cross section of the light emitting and receiving module of FIG.

FIG. 3 is a front view including a partial cross section of the light emitting and receiving module of FIG. 1;

FIG. 4 is a side view including a partial cross section of the light emitting and receiving module of FIG. 1;

FIG. 5 is a side view of a light emitting element lens assembly for describing a manufacturing process of the light emitting and receiving module of FIG. 1;

FIG. 6 is a side view of the light emitting / receiving module for describing a manufacturing process of the light emitting / receiving module of FIG. 1;

FIG. 7 is a basic configuration diagram of a conventional one-core optical fiber bidirectional communication system.

8 is a configuration diagram showing a state in which respective components of the light emitting / receiving device of FIG. 7 are integrated.

FIG. 9 is a basic configuration diagram of another conventional one-core optical fiber bidirectional communication system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-core optical fiber bidirectional communication system 2 Optical fiber cable 3 Light emitting / receiving module (light emitting / receiving device) 4 Receptacle 5 Optical plug 6 Optical connector 7 Ferrule 8 Optical fiber 9 Terminal 10 Small diameter section 11 Light emitting element (Light emitting means) 12 Light receiving element (light receiving means) 13 Light propagation member 14 Light emitting surface 15, 17 Terminal 16 Light receiving surface 18 Base member 19 Lens 20 Light emitting element lens assembly

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/135 10/13 10/12 F term (Reference) 2H037 AA01 BA02 BA11 CA11 DA03 DA05 DA16 5F041 AA43 DA46 EE01 EE17 EE22 FF14 5F088 AA01 BA15 BB01 EA11 JA06 5K002 AA05 AA07 BA02 BA31 DA42 FA01

Claims (7)

[Claims] A light-emitting means for converting an electric signal into an optical signal; a light-receiving means for converting an optical signal into an electric signal; A light propagating member for propagating light to the means, wherein a lens protruding toward the terminal is formed at one end of the light propagating member facing the terminal and the one end. The light receiving means is disposed at the other end with respect to the light, and the light emitted from the terminal to the light receiving means is propagated from the one end to the other end, and the light emitting means is embedded in the light propagation member. A light-emitting / light-receiving device, wherein the light from the light-emitting means is transmitted toward the terminal. 2. The light emitting / receiving device according to claim 1, wherein an area of a light receiving surface of the light receiving unit is larger than an area of a light emitting surface of the light emitting unit. 3. The light emitting / receiving device according to claim 1, wherein a width of the lens is larger than a diameter of the terminal. 4. The light emitting / receiving device according to claim 1, wherein an anti-reflection film is formed on the lens and / or the terminal. 5. The light-emitting / light-receiving device according to claim 1, wherein a wavelength selection filter is arranged between said light-emitting means and said light-receiving means. 6. A single-core optical fiber bidirectional communication system, wherein the light emitting / receiving device according to claim 1 is disposed at both ends of one optical fiber. 7. The two-way optical fiber communication system according to claim 6, wherein the two-way communication system is mounted on a vehicle such as an automobile.