JPH11261533A - Optical transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmitter-receiver which increases optical transmission efficiency by separating transmitted light from received light by the difference of optical transmission modes. SOLUTION: This optical transmitter-receiver 1 multiplexes transmitting light L1 and receiving light L2 which are opposite in a single optical transmission path 11, performs bi-direction optical communication, has a transmitting light generating means 2 that generates the light L1 of a specified single mode and separates the light L1 from the light L2 of unspecified plural modes which is acquired by dispersion to light of the unspecified plural modes in an optical transmission process in the path 11 by the difference of optical transmission modes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission / reception apparatus for multiplexing opposing transmission light and reception light using a single optical transmission line to perform bidirectional communication.

[0002]

2. Description of the Related Art A method of transmitting a signal by optical communication has been increasingly required due to diversification of information communication. When a signal is transmitted by optical communication, a single-core bidirectional communication line system using one optical fiber or a two-core bidirectional communication line system using two or more optical fibers is usually used. .

[0003]

In the conventional two-way optical communication, two optical transmission lines are prepared to optically transmit opposing transmission light and reception light on different lines. However, the use of two optical transmission lines doubles the cost of the optical transmission line, and also makes it difficult to miniaturize the connector of the optical transmission line and the entire optical transceiver. On the other hand, a technique for multiplexing the transmission light and the reception light on a single optical transmission line has also conventionally existed. For example, CDM: Carrier D
It is an visionMultiplex. The CDM is a method of optically transmitting transmission light and reception light as carriers having different timings, in other words, as packets with shifted times. This is half-duplex bidirectional optical communication, which is also called a ping-pong system, and cannot cope with full-duplex bidirectional optical communication in which transmission light and reception light travel on an optical transmission line simultaneously.

[0004] Accordingly, full-duplex two-way optical communication is supported.
A technique for multiplexing transmission light and reception light on a single optical transmission line also exists conventionally. For example, WDM:
Wavelength Division Multi
plex. WDM is a method of transmitting transmission light and reception light at different wavelengths, that is, putting transmission light and reception light having different light transmission wavelengths on one optical transmission line. In this case, by using a wavelength-selective optical element to separate transmission light and reception light multiplexed into one,
Light loss during separation can be kept small. However, use of two types of optical transmission wavelengths naturally requires two types of optical transmission / reception devices, and both ends of one optical transmission line must be terminated by different types of optical transmission / reception devices.

As described above, within the scope of the prior art, wavelength division multiplexing is appropriate for realizing full-duplex bidirectional optical communication in which opposing transmission light and reception light are multiplexed on a single optical transmission line. ,
However, it is necessary to use two types of optical transmitting and receiving devices properly. This proper use can be dealt with relatively easily in a centralized management network, but it is very difficult to deal with it in a parallel distributed network. In a centralized management network, since the master-slave relationship between nodes is fixed, as in the case of a server-client, two types of optical transmitting / receiving devices may be uniquely associated with this master-slave relationship. However, in the parallel distributed network, the master-slave relationship of the nodes is arbitrarily changed, or the master-slave relationship does not exist, so that two types of optical transmitting / receiving apparatuses cannot be uniquely associated.

Assuming that next-generation consumer optical networks, especially optical home networks, will be of a parallel distributed type, there is a problem with wavelength division multiplexing as described above. Therefore, it is necessary to perform full-duplex optical communication in which transmission light and reception light are multiplexed on a single optical transmission line using the same optical transmission wavelength for transmission light and reception light. Here, a wavelength-selective optical element cannot be used to separate transmission light and reception light multiplexed into one,
Alternative separation methods are required.

When a mere half mirror is used to separate transmission light and reception light multiplexed on a single optical transmission line (in the case of using a half mirror, to be precise, the transmission light and the reception light are separated). Although it cannot be said), the coupling efficiency of the transmitted light from the light emitting element to the optical transmission line is almost 50%, that is, the light amount loss-3d.
B, the coupling efficiency of the received light from the optical transmission line to the light receiving element is also approximately 50%, and the clogging light amount loss is −3 dB. Therefore, if only the sum of the two is defined as the optical transmission efficiency, it is approximately 25%, −6d.
B. Accordingly, it is an object of the present invention to solve the above-mentioned problem and to provide an optical transmitting and receiving apparatus capable of increasing optical transmission efficiency by separating transmission light and reception light by a difference in an optical transmission mode.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide an optical transmission / reception apparatus for multiplexing opposing transmission light and reception light on a single optical transmission line to perform bidirectional optical communication. Having transmission light generating means for generating transmission light of a specific single mode, and dispersing the transmission light of the specific single mode into unspecified multiple mode light in an optical transmission process in a single optical transmission line. This is achieved by an optical transmission / reception apparatus characterized in that received light of an unspecified multiple mode is separated by a difference in an optical transmission mode.

In the present invention, opposing transmission light and reception light are
When performing multiplexing in a single optical transmission line to perform bidirectional communication, the transmission light generation means generates transmission light in a specific single mode. This specific single-mode transmission light is separated into unspecified multiple-mode reception light obtained by dispersing it into unspecified multiple-mode light in the optical transmission process on a single optical transmission line, and is separated by the difference in the optical transmission mode. I do. Thereby, when multiplexing is performed in a single optical transmission line to perform two-way communication, the optical transmission efficiency can be greatly increased.

In the present invention, preferably, the specific single-mode transmission light of the transmission light generating means is made incident on a single optical transmission path, and the unspecified multiple-mode reception light emitted from the single optical transmission path is converted. There is provided a receiving light reflecting means for guiding the reflected light to a light receiving means for receiving the receiving light, and the receiving light reflecting means serves as a heat sink for dissipating the heat generated by the transmitting light generating means. Thereby, the transmission light of the specific single mode and the reception light of the unspecified plural modes can be separated by the reception light reflection means, so that the optical transmission efficiency can be increased. Further, since the reception light reflection means is a heat sink. In addition, the heat radiation efficiency can be increased by avoiding a rise in the temperature of the transmission light generating means.

In the present invention, preferably, the transmitting light generating means is a laser light source, and is disposed in the receiving light reflecting means. Thus, the transmitting light generating means can be provided in the receiving light reflecting means, so that the size of the apparatus can be reduced. In the present invention, preferably, transmission light having a polarization component is reflected by a polarization separation element and is incident on a single optical transmission path, or transmission light having a polarization component is transmitted by a polarization separation element to form a single transmission light. The light is made to enter the optical transmission line. In the present invention, preferably, the transmission light generating means includes:
A laser diode, and the single optical transmission line is a multimode optical fiber.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows an example in which a so-called connected home is connected to an information provider in the world by a network as an object to which the optical transceiver of the present invention can be applied. Various electric devices, information devices, and the like are arranged in the house 200. The house 200 provides information from an external content provider 201 to the home server 203 via the access network 202, and sends information from the home server 203 to the content provider 201 via the access network 202. You can do it. The house 200 is provided with an antenna 204 from which information from the content provider 201 is transmitted to the satellite 2.
05. As a method of providing this information, in addition to a satellite link using the artificial satellite 205, a method using terrestrial waves can be adopted.

In the house 200 shown in FIG. 1, a control system 210 for the above-described devices and a multimedia system 220 are provided. The control system 210 is a device used in a general household, for example, an electric light 210A, a refrigerator 210B, a microwave oven 210.
C, a signal path for controlling the indoor unit 210D of the air conditioner, the electric carpet 210E, the gas water heater 210F, the home medical device 210G, and the like is formed. On the other hand, the multimedia system 220 is a device corresponding to the multimedia age, such as a computer 220A, a telephone 220B, and an audio device 220.
C, portable information device 220D, digital still camera 2
20E, a printer / facsimile 220F, a digital video camera 220G, a game machine 220H, a DVD (digital versatile disk or digital video disk: trademark) player 220I, and a signal path for controlling a television receiver 220J and the like. The various devices of the control system 210 and the multimedia system 220 transmit and receive optical signals to and from the home server 203 using an optical fiber described later using a single-core bidirectional optical communication system. It can perform on / off control of each device, supply information to various devices, and perform operations such as switching on and off the television receiver 220J of the multimedia system 220, and supplying and sending information. It has become.

FIG. 2 shows an example of the optical transceiver 1 for connecting the home server 203 between various devices of the control system 210 or the multimedia system 220 shown in FIG. The optical transmitting and receiving apparatus 1 is used for a so-called single-core bidirectional optical communication circuit. The optical fiber 11 can multiplex and transmit and receive optical signals between one device M1 and the other device M2. it can. The optical transceiver 1 is provided in each of these devices M1 and M2. These devices M1 and M2 are connected to the control system 21 shown in FIG.
0, each device of the multimedia system 220, the home server 203, and the like.

FIG. 3 shows a preferred embodiment of the optical transceiver 1 shown in FIG. Optical transmitting / receiving device 1 of FIG.
Has a package 7, a receiving light reflecting unit 4 also serving as a heat sink, a laser light source 2, a light receiving unit 5, and the like. The package 7 contains the received light reflecting means 4 and the light receiving means 5 which are both heat sink blocks. A multi-mode type optical fiber 11 is connected to the connection portion 7A of the package 7.
11A are inserted and arranged. The received light reflecting means 4 housed in the package is made of a material having excellent heat dissipation such as aluminum, and is electrically connected to the ground GND. The reception light reflecting means 4 has a triangular shape when viewed in cross section, and has a receiving hole 4A formed in the center thereof. The laser light source 2 as transmission light generating means is disposed in the accommodation hole 4A. The laser light source 2 is connected to an external control system via a transmission amplifier 2A.

The light receiving means 5 is, for example, a photodiode and is arranged on the package 7.
For example, a photodiode can be used, and is connected to an external signal processing system via the receiving amplifier 5A.
The reception light reflection means 4 has a reception light reflection surface 4B.
The accommodation hole 4A is sealed with, for example, a sealing resin lid 4C. The laser light source 2 is sealed in the housing hole 4A by a cover glass 4D for laser sealing provided in the housing hole 4A.

The laser light source 2 is transmission light generating means for generating a specific single-mode transmission light L1, and the transmission light L1 generated by the laser light source 2 passes through a cover glass 4D and ends of the multi-mode optical fiber 11. The light enters the portion 11A. The unspecified multiple-mode received light L2 that has passed through the optical transmission process of the multimode optical fiber 11 spreads out from the end 11A of the multimode optical fiber 11, is reflected by the received light reflecting surface 4B, and is received. The light can be received by the means 5. When the light receiving means 5 receives the reception light L2,
The signal is sent to the signal processing system via the receiving amplifier 5A.

In the embodiment shown in FIG. 3, the receiving light reflecting means 4 converts the specific single-mode transmission light L1 into an unspecified plural number in the optical transmission process in the multimode optical fiber 11, which is a single optical transmission line. The received light L1 of the unspecified plural modes obtained by being dispersed into the light of the mode is separated by the received light reflecting surface 4B by the difference of the optical transmission mode. Thereby, the transmission light L1 and the reception light L2 can be efficiently separated. In addition, since the received light reflecting means 4 plays a role of a heat sink, it is possible to effectively absorb the heat generated by the laser light source 2 and radiate it to the outside, thereby preventing a problem such as an increase in the temperature of the laser light source 2.

Next, another embodiment of the present invention will be described with reference to FIGS. In the embodiment of the optical transmitting and receiving apparatus described in FIG. 4 and subsequent figures, the opposing transmission light and reception light are
In bidirectional optical communication multiplexed on a single optical transmission line, the same light transmission wavelength is used for the transmission light L1 and the reception light L2, and the transmission light and the reception light are not the difference in the light transmission wavelength, but the TE. (Tr
inverse electric mode (waveguide mode having no electric field component in the wave propagation direction) or TM
(Transverse magnetic mod
e; a mode of a waveguide that does not have a magnetic field component in the wave propagation direction). That is, the following optical transmitting and receiving apparatus 1 uses a laser diode as a light emitting element, a multimode optical fiber as an optical transmission line, and a transmission light having a polarization component based on an oscillation mode inherent to the laser diode. The received light having a plurality of polarization components dispersed by the above is transmitted and received after being polarization-separated.

At least 16 types of optical transmission / reception devices using polarization separation can be considered. That is, option (1): transmitting light having a specific polarization component,
The light is "reflected or transmitted" by the polarization separation element. Option (2): “Prism type or plate type” is used for the polarization separation element. Option (3): Optical elements such as a light emitting element and a light receiving element
"Discrete or integrated". Option (4): “Use or not use” a condenser lens for optical coupling between a light emitting element or a light receiving element and an optical transmission line. There are 16 types that can be considered from the matrix of the above four options. Some of these types are illustrated below. The operation principles of the above 16 types are roughly described into two types according to option (1). That is, a transmission light having a specific polarization component is reflected by a polarization splitting element, a “transmission light reflection type”, and a transmission light having a specific polarization component is transmitted by a polarization separation element, a “transmission light transmission type”. It is.

FIG. 16 shows the principle of operation of the "transmission light reflection type". First, the transmission light L1 is excited in an oscillation mode unique to the laser diode LD, and is polarized by a polarization splitting element, that is, a polarization beam splitter (PBS: Polarized Beam S).
plitter). Here, the coating of the polarizing beam splitter BS is, for example, S-polarized reflectance R
s = 99%, S polarized light transmittance Ts = 1%, P polarized light reflectance Rp = 1%, P polarized light transmittance Tp =
99% (due to the above, Ts = 99%, Rp
= 99% coating is difficult in practice). Then, the laser diode is mounted so that the polarization component of the oscillation mode of the laser diode LD becomes S-polarized light, relative to the polarization beam splitter BS. Then, the transmission light L1 that becomes S-polarized when viewed from the polarization beam splitter BS.
Is 99% at the polarization beam splitter BS, that is, almost totally reflected, and the coupling efficiency of the transmission light from the laser diode LD to the multi-mode optical fiber 11 becomes almost 100%. On the other hand, since the specific polarization component is not preserved in the multi-mode optical fiber 11, the transmission light L1 incident from one end of the fiber with S polarization is composed of two orthogonal polarizations of S polarization and P polarization and innumerable polarization components therebetween. The received light L2 is emitted from the other end of the optical fiber 11 and is again irradiated on the polarization beam splitter. Since the received light L2 is, as it were, an innumerable number of polarized light components made uniform, at this time, the received light L2 is (1% +
99%) ÷ 2 = 50%, that is, almost semi-transmitted, and the coupling efficiency of the received light from the multi-mode optical fiber 11 to the photodiode PD becomes almost 50%. As a result,
Multi-mode optical fiber 11 from laser diode LD
Efficiency of transmission light to the multimode optical fiber 1
The sum of the coupling efficiency of the received light from 1 to the photodiode PD, that is, the optical transmission efficiency as defined in the embodiment of the present invention is approximately 50%.

FIG. 17 shows the operation principle of the "transmission light transmission type". Similarly to the above-mentioned reflection type, the coating of the polarizing beam splitter BS is, for example, S-polarized reflectance Rs = 99%, S
It is assumed that the polarization transmittance Ts = 1%, the P-polarization reflectance Rp = 1%, and the P-polarization transmittance Tp = 99%, which are orthogonal to the S-polarized light.
Then, the laser diode LD is mounted in such a manner that the polarization component of the oscillation mode of the laser diode LD becomes P-polarized light, which is opposite to that described above, relative to the polarization beam splitter BS. Then, when viewed from the polarization beam splitter BS, the transmission light L1 that becomes P-polarized light here is transmitted by the polarization beam splitter at 99%, that is, almost completely, and transmitted light from the laser diode LD to the multimode optical fiber 11 is transmitted. The coupling efficiency is almost 100%. On the other hand, the transmission light L1 that has propagated through the multimode optical fiber becomes two orthogonal polarizations, P-polarization and S-polarization, and reception light L2 including an innumerable polarization component therebetween, and exits from the other end of the fiber.
The light is again irradiated on the polarizing beam splitter BS. At this time,
The reception light L2 is substantially semi-reflected by the polarization beam splitter BS, and the coupling efficiency of the reception light from the multi-mode optical fiber 11 to the photodiode PD becomes approximately 50%. Then, as a result, the sum of the coupling efficiency of the transmission light from the laser diode LD to the multi-mode optical fiber 11 and the coupling efficiency of the reception light from the multi-mode optical fiber 11 to the photodiode PD, that is, the present embodiment The light transmission efficiency defined by the above is approximately 50%. As described above, the light transmission efficiency due to the introduction of the polarizing beam splitter is
It is almost 50%. On the other hand, as described above, in the conventional separation using the half mirror, the light transmission efficiency is approximately 25%. This means that the light transmission efficiency is doubled and increased by +3 dB by the polarization separation method. In this way, in bidirectional optical communication in which opposing transmission light and reception light are multiplexed on a single optical transmission line, if transmission light and reception light are separated by a difference in optical transmission mode, transmission light and reception light can be separated. Even if the same light transmission wavelength is used for light, the light transmission efficiency can be improved.

In the embodiment of the optical transmitting / receiving apparatus of the present invention described in FIG. 4 and subsequent figures, a polarization separating element is used instead of the receiving light reflecting means 4 having the receiving light reflecting surface 4B which is a mirror surface in FIG. I have. The optical transceiver 1 of FIG.
7, a polarization beam splitter (polarization splitting element) 24, a laser diode (laser light source) 22, a photodiode 25 as a light receiving means, and the like. The package 27 has a connection portion 27A, and the end portion 11A of the multimode optical fiber 11 is connected to the connection portion 27A.

The polarizing beam splitter 24 includes the package 2
7 and the polarizing beam splitter 24 is
It is an S-polarized reflection plate type. The polarization beam splitter 24 is coated so as to reflect the S-polarized light almost completely and transmit the P-polarized light almost completely. The photodiode 25 is connected to a signal processing unit via a reception amplifier 25A. The laser diode 22 is connected to the control unit via the transmission amplifier 22A, and is mounted so that the direction of the polarization component in the oscillation mode becomes S-polarized relative to the polarization beam splitter 24. The laser diode 22 transmits the transmission light L1 in the specific single mode and reflects it by the polarization beam splitter 24,
The light can enter the end 11A of the multimode optical fiber 11. Unspecified multiple-mode received light L2 obtained by being dispersed into unspecified multiple-mode light in the optical transmission process of the multimode optical fiber 11 is received by the photodiode 25 through the polarization beam splitter 24.

In the embodiment shown in FIG. 4, the transmission light L1 generated by the laser diode 22 is S-polarized. On the other hand, when the reception light L2 is emitted from the end 11A of the multi-mode optical fiber 11, the light becomes a light in which the S + P polarized light and other innumerable polarized light components are uniformly distributed, and further passes through the polarization beam splitter 24. The light is received by the photodiode 25 as P-polarized light. FIG.
The optical transmitting and receiving apparatus 1 does not use a condensing lens, but has an optical system configuration using so-called discrete components, and a plate-type polarization beam splitter 24 includes a package 27.
And the transmission light L1 of the laser diode 22
Are almost totally reflected by the polarization beam splitter 24.

Next, the optical transmitting and receiving apparatus 1 shown in FIG. 5 has a package 37, a polarizing beam splitter 34, a photodiode (receiving means) 35, a laser diode (transmitting light generating means) 32, and the like. Connection part 37 of package 37
A is connected to an end 11A of the multimode optical fiber 11. The polarization beam splitter 34 is of a P-polarized light transmission plate type, and is coated so as to substantially totally reflect S-polarized light and substantially completely transmit P-polarized light.

The laser diode 32 is mounted so that the direction of the polarization component in the oscillation mode becomes P-polarized light relative to the polarization beam splitter 34. The laser diode 32 is connected to a control unit via a transmission amplifier 32A. The photodiode 35 serving as a light receiving unit is connected to a signal processing unit via a receiving amplifier 35A.
The transmission light L1 generated by the laser diode 32 includes a P-polarized component, and the transmission light L1 passes through the polarization beam splitter 34 and is transmitted to the end 1 of the multimode optical fiber 11.
1A.

On the other hand, when the reception light L2 is emitted from the end 11A, the reception light L2 becomes light in which S + P polarized light and other innumerable polarization components are multiplied, and is reflected by the polarization beam splitter 34. , S-polarized light components can be received by the photodiode 35. As described above, in the optical transmitting and receiving apparatus 1 of FIG. 5, the plate-type polarization beam splitter 34 is incorporated as a configuration of an optical system using so-called discrete components without using a condenser lens, and transmission from the laser diode 32 is performed. The light L1 is transmitted almost completely.

Next, an embodiment of the optical transceiver shown in FIG. 6 will be described. 6 includes a package 47, a polarization beam splitter 44, and a photodiode 4.
5, a laser diode 42 and the like. The end portion 11A of the multimode optical fiber 11 is connected to the connection portion 47A of the package 47. Polarizing beam splitter 4
Reference numeral 4 is coated so as to reflect the S-polarized light almost completely and transmit the P-polarized light almost completely. Laser diode 42
Are mounted such that the direction of the polarization component of the oscillation mode becomes S-polarized light relative to the polarization beam splitter 42. The laser diode 42 is connected to a control unit of the laser diode via a transmission amplifier 42A. The photodiode 45 is connected to a signal processing unit via a receiving amplifier 45A.

Transmission light L generated by laser diode 42
1 has an S-polarized component, is reflected by the polarization beam splitter 44, and is incident on the end 11A of the multimode optical fiber 11. On the other hand, when the received light L2 is emitted from the end 11A, the S + P polarized light and the myriad other polarized light components are in a uniform state, and pass through the polarization beam splitter 44 to become the P polarized light. The component can be received by the photodiode 45.

The optical transmitting / receiving apparatus 1 shown in FIG. 6 has an optical system configuration using so-called discrete components without using a condensing lens, and incorporates an S-polarization reflecting prism type polarization beam splitter 44 and a laser. The transmission light from the diode 42 is almost totally reflected.

The optical transceiver 1 shown in FIG.
7, polarization beam splitter 54, laser diode 5
5, a photodiode 52 and the like. An end 11A of the multimode optical fiber 11 is connected to a connection portion 57A of the package 57. Polarizing beam splitter 5
Reference numeral 4 denotes a P-polarized light transmitting prism type, which is coated so as to substantially totally reflect S-polarized light and substantially completely transmit P-polarized light.

The laser diode 55 is mounted so that the direction of the polarization component in the oscillation mode becomes P-polarized light relative to the polarization beam splitter 54. The laser diode 55 is connected to a control unit of the laser diode via a transmission amplifier 55A. The photodiode 52 is connected to a signal processing unit via a receiving amplifier 52A. P-polarized transmission light L transmitted by the laser diode 55
1 enters the end 11A of the multimode optical fiber 11 through the polarization beam splitter 54. On the other hand, the reception light L2 transmitted from the multimode optical fiber 11
Is emitted in a state where S + P polarized light and countless other polarized light components are made uniform, reflected by the polarization beam splitter 54, and the S polarized light component can be received by the photodiode 52.

The optical transmitting and receiving apparatus 1 shown in FIG. 7 has an optical system composed of so-called discrete components that do not use a condensing lens, and incorporates a P-polarization transmitting prism type polarizing beam splitter 54 and a laser diode. The transmission light L1 from the light source 55 is almost completely transmitted.

Next, the optical transmitting / receiving apparatus 1 shown in FIG. 8 will be described. The optical transceiver 1 has a package 67, a polarization beam splitter 64, a photodiode 62, a laser diode 65, and the like. Package connection 67A
Is connected to the end 11A of the multimode optical fiber 11. The polarization beam splitter 64 is of the S-polarization reflection prism type, and is coated so as to reflect the S-polarized light almost completely and transmit the P-polarized light almost completely.

The photodiode 62 includes a receiving amplifier 62
A is connected to the signal processing unit via A. The laser diode 65 is connected to a control unit of the laser diode via a transmission amplifier 65A. Polarizing beam splitter 6
A condenser lens 69 is arranged between the optical fiber 4 and the end 11A of the optical fiber 11. The laser diode 65 is mounted so that the direction of the polarization component in the oscillation mode becomes S-polarized relative to the polarization beam splitter 64. The transmission light L1 generated by the laser diode 65 is condensed by the condensing lens 65 and is transmitted to the end 1 of the multimode optical fiber 11.
1A.

On the other hand, the received light L2 has an end portion 11A in a state where S + P polarized light and an infinite number of other polarized light components are carried and made uniform.
In a state where the light is condensed by the condenser lens 69, the light passes through the polarization beam splitter 64, becomes a P-polarized light component, and is received by the photodiode 62.

The light transmitting / receiving device 1 shown in FIG.
9, an optical system composed of discrete components is used, and an S-polarization reflecting prism type polarizing beam splitter 6 is used.
4 and the transmission light L1 from the laser diode 65
Is almost totally reflected.

Next, the optical transceiver 1 shown in FIG. 9 includes a package 77, a polarizing beam splitter 74, and a laser diode 7.
5, a photodiode 72, a condenser lens 79, and the like. The end portion 11A of the multimode optical fiber 11 is connected to the connection portion 77A of the package 77. The polarization beam splitter 74 is of a P-polarized light transmission prism type, and is coated so as to substantially totally reflect S-polarized light and transmit almost completely P-polarized light. Laser diode 7
5 is connected to the control unit of the laser diode via the transmission amplifier 75A. The photodiode 72 is connected to a signal processing unit via a receiving amplifier 72A.

The condensing lens 79 includes the polarization beam splitter 7
4 and the end 11A. The transmission light L1 emitted from the laser diode 75 has a P-polarized component, passes through the polarization beam splitter 74, and passes through the condenser lens 79.
And is incident on the end 11A. The received light L2 that has passed through the multimode optical fiber 11 is S +
The P-polarized light and countless other polarized components are made uniform and reflected by the polarization beam splitter 74 to become S-polarized light, which can be received by the photodiode 72.

The light transmitting / receiving device 1 shown in FIG.
9, the optical system is composed of discrete components, and a P-polarized transmission prism-type polarization beam splitter is incorporated so that the transmission light L1 from the laser diode 75 is transmitted almost completely.

The optical transceiver 1 shown in FIG.
7, polarization beam splitter 84, photodiode 8
2. It has a laser diode 85, a condenser lens 89, and the like. An end 11A of the multimode optical fiber 11 is connected to a connection portion 87A of the package 87. The polarization beam splitter 84 is of the S-polarization reflection prism type, and is coated so as to reflect the S-polarized light almost completely and transmit the P-polarized light almost completely. The condenser lens 89
It is arranged between the polarization beam splitter 84 and the end 11A.

The photodiode 82 includes a receiving amplifier 82
A is connected to the signal processing unit via A. The laser diode 85 is connected to a control unit of the laser diode via a transmission amplifier 85A. The laser diode 85 and the photodiode 82 are provided integrally with one substrate, and the polarization beam splitter 84
Are also provided integrally with the substrate 86.
The transmission light L1 emitted from the laser diode 85 is reflected by the polarization beam splitter 84 and enters the end 11A of the multimode optical fiber 11 as an S-polarized component. The received light L2 from the multimode optical fiber 11 is S + P
The polarized light and the myriad other polarized light components are brought into a uniform state. After being condensed by the condensing lens 89, the light passes through the polarization beam splitter 84 and becomes the P-polarized light.
2 is received.

The optical transmitting and receiving apparatus 1 shown in FIG. 10 has an optical system composed of integrated components using a condensing lens 89. The optical transmitting and receiving apparatus 1 incorporates an S-polarized reflecting prism type polarizing beam splitter 84 and a laser diode. The transmission light L1 from the light source 85 is almost totally reflected.

Next, the optical transceiver 1 shown in FIG. 11 has a package 97, a polarization beam splitter 94, a laser diode 95, a photodiode 92, a condenser lens 99 and the like. The polarization beam splitter 94 is of a P-polarized light transmission prism type, and is coated so as to reflect the S-polarized light almost completely and transmit the P-polarized light almost completely. The polarization beam splitter 94, the laser diode 95 and the photodiode 92 are integrally set for one substrate 96. The laser diode 95 is connected to a control unit of the laser diode via a transmission amplifier 95A. The photodiode 92 is connected to the receiving amplifier 9.
It is connected to the signal processing unit via 2A.

Transmission light L emitted from laser diode 95
1 is condensed by a condenser lens 99 in a form including a P-polarized component, and is incident on the end 11A of the multimode optical fiber 11. This end 11A is connected to the connection 97A of the package 97. The received light L2 that has passed through the multimode optical fiber 11 is condensed by the condensing lens 99 and reflected by the polarization beam splitter 94 in a state where the S + P polarized light and a myriad of other polarized light components are made uniform, and is reflected by the polarizing beam splitter 94 to be S polarized light. The component is received by the photodiode 92.

The optical transmission / reception apparatus 1 shown in FIG. 11 has an optical system configuration of integrated components using a condensing lens 99, and incorporates a P-polarized transmission prism type polarization beam splitter 94 and a laser diode. Transmitted light L from 95
1 is almost completely transmitted.

Next, the optical transmitting / receiving apparatus shown in FIG. 12 will be described. The optical transceiver 1 includes a package 107, a condenser lens 109, a photodiode 102, and a laser diode 1.
05 etc. Connection 107 of package 107
The end A of the multimode optical fiber 11 is connected to A. The polarization beam splitter 104 is disposed almost integrally with the photodiode 102 and the laser diode 105. The polarizing beam splitter 104 is of a P-polarized light transmission prism type, and is coated so as to substantially totally reflect S-polarized light and substantially completely transmit P-polarized light.

The laser diode 105 is mounted so that the direction of the polarization component in the oscillation mode becomes P-polarized light relative to the polarization beam splitter 104. The laser diode 105 is disposed so as to be embedded in the polarization beam splitter 104. Laser diode 105
Is connected to the control unit of the laser diode via the transmission amplifier 105A. The photodiode 102 is connected to a signal processing unit via a receiving amplifier 102A. The transmission light L1 of the laser diode 105 is condensed by the condensing lens 109,
At the end 11A. Multimode optical fiber 1
After being collected by the condenser lens 109, the received light L2 from 1 is reflected by the polarization beam splitter 104 to become an S-polarized component, and can be received by the photodiode 102.

The optical transmission / reception apparatus 1 shown in FIG. 12 has an optical system composed of integrated components using a condensing lens 109. The optical transmission / reception apparatus 1 incorporates a polarization beam splitter 104 of a P polarization transmission prism type and a laser diode 105. Is transmitted almost completely.

FIG. 13 is a perspective view showing the optical transceiver 1 shown in FIG. 10 described above. The optical transceiver 1 is set on the circuit board 120.

FIG. 14 shows a specific example of the structure of the optical transceiver 1 as shown in FIG. As the multi-mode optical fiber, for example, a multi-mode plastic optical fiber can be used.
1 and attached to the receptacle 122. The end 11A of the optical fiber 11 is
Face to face.

The integrated optical module 130 is mounted on the circuit board 120.
, A photodiode 82, a polarization beam splitter (prism) 84, a laser diode 85, and the like are arranged. The laser diode 85 is connected to a connection pin 85A via a driver 85A. The photodiode 132 includes an amplifier 82A and a current-voltage amplifier 82B.
Is connected to the pin 82C. A condenser lens 89 is provided between the mirror 123 and the module 130.

In the embodiment of the present invention, in bidirectional optical communication in which opposing transmission light and reception light are multiplexed on a single optical transmission line, light of a specific single mode is unspecified in an optical transmission process. By using an optical transmission line that disperses the light in multiple modes, the transmission light and the reception light are separated by the difference in the optical transmission mode,
Optical transmission efficiency can be increased.

In the embodiment of the present invention, in bidirectional optical communication in which opposing transmission light and reception light are multiplexed on a single optical transmission line, light of a specific single mode is unspecified in an optical transmission process. A single-mode light is transmitted and an unspecified multiple-mode light is received using an optical transmission line that disperses the light into a plurality of modes. The same light transmission wavelength is used for the transmission light and the reception light, and the transmission light and the reception light are separated not by the difference in the light transmission wavelength but by the difference in the light transmission mode. From the light emitting element to the optical transmission line, increase the coupling efficiency of the transmission light, and, from the optical transmission line to the light receiving element, without impairing the coupling efficiency of the reception light,
Increase light transmission efficiency.

A laser diode is used as a light emitting element for transmitting light of a specific single mode, and an optical transmission line for dispersing transmission light pumped in a unique oscillation mode of the laser diode into light of an unspecified plurality of modes. A multimode optical fiber is used. A transmission light having a polarization component based on an oscillation mode unique to a laser diode, and a reception light having a plurality of polarization components dispersed by a multimode optical fiber,
Transmit and receive after separating the polarization.

In the embodiment of the present invention, the transmission light and the reception light are separated by the difference in the optical transmission mode in the bidirectional optical communication in which the transmission light and the reception light facing each other are multiplexed on a single optical transmission line. As an example, if polarization separation is used, as described above,
The light transmission efficiency increases by +3 dB. The value of +3 dB enables the transmission distance to be extended by +20 m in the case of a multimode optical fiber made of acrylic plastic, for example. Because the optical loss of acrylic plastic optical fiber (as of January 1998) is -0.15 dB
/ M, 3 dB / 0.15 dB / m = 20 m. Conversely, if the emission light amount of the light emitting element is reduced by half by the increase of the light transmission efficiency by +3 dB, the operating life of the light emitting element can be extended. For example, in a laser diode, in general,
It is said that the square of the emitted light quantity and the operating life are inversely proportional, so halving the emitted light quantity extends the operating life by four times.

As described above, by separating the transmission light and the reception light by the difference in the optical transmission mode, the transmission distance and the life of the light emitting element can be extended. Further, since the same optical transmission wavelength is used for the transmission light and the reception light, it is possible to provide an optical transmission / reception apparatus which is easily adapted to not only a centralized management network but also a parallel distributed network. In addition, since bidirectional optical communication is performed using one optical transmission line, the size of the optical transceiver and the connector can be easily reduced. Such an optical transmission / reception device is optimal for a next-generation consumer optical network, particularly an optical home network.

The present invention is not limited to the above embodiment. In the above-described embodiment, the embodiment of the optical transmission / reception device of the present invention is used for constructing a home control system or multimedia network. However, the present invention is not limited to this, and the optical transmitting and receiving apparatus of the present invention can be applied to a communication system for exchanging various kinds of information in a moving body such as an automobile, an airplane, and a ship. Although a laser light source is used as the light emitting means, the wavelength used by the laser light source is not limited to 650 nm, and it is of course possible to use another wavelength region. The light emitting means is not limited to the laser light emitting source, and it is of course possible to use other types of light emitting sources.

[0061]

As described above, according to the present invention,
By separating the transmission light and the reception light by the difference in the optical transmission mode, the optical transmission efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example in which an optical transmission / reception device of the present invention is used for information communication of a control system or a multimedia system in a home.

FIG. 2 is a diagram simply showing an example in which the optical transmitting / receiving device of the present invention is disposed between devices.

FIG. 3 is a diagram showing a preferred embodiment of the optical transceiver of the present invention.

FIG. 4 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 5 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 6 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 7 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 8 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 9 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 10 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 11 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 12 is a diagram showing another preferred embodiment of the optical transceiver of the present invention.

FIG. 13 is a perspective view showing an embodiment of the present invention more specifically.

FIG. 14 is a diagram showing a configuration example of the embodiment in FIG. 13;

FIG. 15 is a diagram functionally showing the embodiment of FIG. 14;

FIG. 16 is a diagram showing an operation principle of a transmission light reflection type.

FIG. 17 is a diagram showing an operation principle of a transmission light transmission type.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical transmission / reception apparatus, 2, 22 ... Laser diode (transmission light generation means), 4 ... Reception light reflection means, 5,
25: photodiode (light receiving means), 7: package, 11: multi-mode optical fiber (single optical transmission line), 24, 34, 44, 54, 64, 74, 8
4, 94, 104: polarization beam splitter (polarization separation element), L1: transmission light, L2: reception light

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyoshi Horie 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hideki Yoshida 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. 72 within Sony Corporation (72) Inventor Shinobu Hidaka 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (6)

[Claims] 1. An optical transmitting / receiving apparatus for performing bidirectional optical communication by multiplexing opposing transmission light and reception light on a single optical transmission line, and a transmission light generation means for generating a specific single mode transmission light. Having a specific single mode transmission light, an unspecified multiple mode reception light obtained by dispersing the unspecified multiple mode light in an optical transmission process in a single optical transmission line, An optical transmission / reception device which is separated by a difference. 2. A specific single-mode transmission light from a transmission light generating means is incident on a single optical transmission line, and receives and reflects unspecified multiple-mode reception light emitted from the single optical transmission line. 2. The optical transceiver according to claim 1, further comprising: a receiving light reflecting unit that guides the light to a light receiving unit that receives light, wherein the receiving light reflecting unit is a heat sink for dissipating heat generated by the transmitting light generating unit. 3. The optical transmitting and receiving apparatus according to claim 2, wherein the transmitting light generating means is a laser light source and is disposed in the receiving light reflecting means. 4. The optical transmitting and receiving apparatus according to claim 1, wherein the transmission light having the polarization component is reflected by the polarization splitting element and is incident on a single optical transmission line. 5. The optical transmitting and receiving apparatus according to claim 1, wherein the transmission light having a polarization component is transmitted through a polarization separation element and is incident on a single optical transmission line. 6. The optical transmitting and receiving apparatus according to claim 1, wherein the transmitting light generating means is a laser diode, and the single optical transmission line is a multimode optical fiber.