JPH04217129A - Bidirectional communication system with same wavelength light - Google Patents

Abstract

PURPOSE:To attain a same wavelength light bidirectional communication system where the communication is possible between both transmission/reception devices set opposite to each other via an optical fiber despite increase of the section of the optical fiber by connecting these two transmission/reception devices via an optical fiber for transmission/reception of the signals of the same wavelength light. CONSTITUTION:The obliquely our parts of the input side of a direct optical amplifier 4 of the UP direction and the output side of a direct optical amplifier 5 of a DOWN direction are connected to each other between the transmission/ reception devices 1 and 2 via a branch type optical fiber 6. Meanwhile the obliquely cut parts of the input side of the amplifier 5 and the output part of the amplifier 4 are connected to each other via a branch type optical fiber 7. An optical bidirectional repeater 10 containing such amplifiers 4 and 5 is set between both devices 1 and 2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention connects opposing transmitting/receiving devices that transmit and receive signals of the same wavelength using a single optical fiber, This invention relates to improvements in a two-way optical communication system with the same wavelength that performs communication using optical signals of the same wavelength.

0002

2. Description of the Related Art FIG. 5 is a block diagram of a conventional optical two-way communication system having the same wavelength. In FIG. 5, an optical signal from the optical transmitting section 20 of the transmitting/receiving device 1 passes through a directional coupler 30, is transmitted via the optical fiber 3, and passes through the directional coupler 31 to the optical receiving section 23 of the transmitting/receiving device 2. input.

An optical signal having the same wavelength as the optical signal of the optical transmitter 20 from the optical transmitter 21 of the transmitter/receiver 2 passes through the directional coupler 31 and is transmitted via the optical fiber 3. The optical signal is inputted to the optical receiving section 22 of the transmitting/receiving device 1.

[0004] As described above, the directional couplers 30 and 31 are used to bidirectionally transmit optical signals of the same wavelength through one optical fiber 3, thereby enabling bidirectional communication of the same wavelength light.

[0005]

[Problem to be Solved by the Invention] However, when the directional couplers 30 and 31 are passed through, there is a problem that a loss of at least 3 dB each and a total of 6 dB or more occurs, shortening the transmission distance and shortening the section of the optical fiber 3. .

An object of the present invention is to provide a two-way communication system using the same wavelength light, which allows communication even if the length of the optical fiber is lengthened.

[0007]

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. As shown in FIG. 1, opposing transmitting/receiving devices 1 and 2 that transmit and receive signals of the same wavelength are connected by an optical fiber 3, and the same wavelength is transmitted between the opposing transmitting and receiving devices 1 and 2 via the optical fiber 3. In a same-wavelength optical bidirectional communication system that communicates using optical signals, between the transmitting and receiving devices 1 and 2,
The input side of the upstream optical direct amplifier 4 and the diagonally cut portion of the output side of the downstream optical direct amplifier 5 are connected by a branched optical fiber 6, and the downstream optical direct amplifier 5
An optical bidirectional repeater 10 is inserted in which the input side of the optical direct amplifier 4 and the diagonally cut portion of the output side of the upstream optical direct amplifier 4 are connected by a branched optical fiber 7.

[0008]

[Operation] According to the present invention, an optical signal from the transmitting/receiving device 1 passes through the branch type optical fiber 6 of the optical bidirectional repeater 10, is amplified by the optical direct amplifier 4, and passes through the branch type optical fiber 7 for transmission/reception. sent to device 2.

The optical signal from the transmitting/receiving device 2 having the same wavelength as the optical signal from the transmitting/receiving device 1 passes through the branch type optical fiber 7 of the optical bidirectional repeater 10 and is amplified by the optical direct amplifier 5.
The signal is sent to the transmitting/receiving device 2 through the branched optical fiber 6.

In this case, based on the principle of a fusion type directional coupler, in the branch type optical fiber 6, the light input from the branch type optical fiber 6 is input to the optical direct amplifier 4 and output from the optical direct amplifier 5. However, the light directed to the input of the optical direct amplifier 4 from the output of the optical direct amplifier 5 is suppressed, and in the branch type optical fiber 7, the light input from the branch type optical fiber 7 is input to the optical direct amplifier 5 and It is input to the output of the optical direct amplifier 4, but the output of the optical direct amplifier 5 is input to the optical direct amplifier 5.
Since the light directed to the input of optical bidirectional repeater 1 is suppressed,
Singing caused by the optical direct amplifier 4 and the optical direct amplifier 5 of 0 is prevented.

Furthermore, the light that is input to the output sides of the optical direct amplifiers 4 and 5 and reflected is emitted to the outside by diagonally cutting the output sides of the optical direct amplifiers 4 and 5.
Now, it is possible to efficiently amplify light of the same wavelength.

Therefore, if the optical bidirectional repeater 10 described above is inserted in the middle of the optical fiber 3 or at both ends, communication can be performed even if the distance between the sections of the optical fiber 3 is increased.

[0013]

[Embodiment] FIG. 2 is a block diagram of a same-wavelength optical two-way communication system according to an embodiment of the present invention, FIG. 3 is a block diagram of an optical two-way repeater according to an embodiment of the present invention, and FIG. FIG. 2 is a block diagram of an optical bidirectional repeater according to an embodiment.

In FIG. 2, an optical signal from an optical transmitter 20 of a transmitter/receiver 1 passes through a branch type optical fiber 6 of an optical bidirectional repeater 10, is amplified by an optical direct amplifier 4, and is amplified by a branch type optical fiber 7, It is sent to the other party through the optical fiber 3, and is transmitted through the branched optical fiber 6 of the optical bidirectional repeater 10 to the optical direct amplifier 4.
It is amplified by
It is sent to the optical receiving section 21 of.

The optical signal having the same wavelength as the optical transmitter 20 from the optical transmitter 21 of the transmitter/receiver 2 is transmitted to the optical bidirectional repeater 10.
The light passes through the branch type optical fiber 7, is amplified by the optical direct amplifier 5, passes through the branch type optical fiber 6 and the optical fiber 3, is sent to the other party, and is directly transmitted through the branch type optical fiber 7 of the optical bidirectional repeater 10. The signal is amplified by the amplifier 5 and sent to the optical receiving section 22 of the transmitting/receiving device 2 through the branched optical fiber 6.

Next, the optical bidirectional repeater 10 will be explained using FIGS. 3 and 4. FIG. 3 shows an optical bidirectional repeater using doped fiber as an optical direct amplifier, and FIG.
An optical bidirectional repeater using a laser diode amplifier is shown as an optical direct amplifier.

In FIG. 3, doped fibers 4-1, 5-1
Pumping light is input from a pumping light source 40 to directly amplify the respective lights. In addition, the input side of the doped fiber 4-1 and the output side of the doped fiber 5-1 are connected to a branch type optical fiber 6 so that the lights of the same wavelength amplified by the doped fibers 4-1 and 5-1 do not sing. The input side of the doped fiber 5-1 and the output side of the doped fiber 4-1 are connected by a branch type optical fiber 7.

The output sides of the doped fibers 4-1 and 5-1 are cut obliquely by about 3 to 4 degrees as shown in FIG. 3(A).
Since the optical fibers to the output side are connected with a rounded tip, the outputs of the doped fibers 4-1 and 5-1 are transmitted to the branch type optical fibers 7 and 6 with almost no loss. Input from optical fibers 7 and 6 and doped fiber 4-1
, 5-1 is emitted to the outside according to Snell's law, and the amount of light reflected back to the branch type optical fibers 7 and 6 is extremely small, so the S/N ratio should be set to a sufficient value. You can.

In FIG. 4, the optical direct amplifier uses laser diode amplifiers 4-2 and 5-2 using waveguides instead of the doped fibers 4-1 and 5-1 in FIG. It has a ring shape, is excited by an excitation circuit 41, and is amplified by stimulated emission.

Of course, the output sides of the laser diode amplifiers 4-2 and 5-2 are cut diagonally, and the optical fibers to the output sides are connected with a rounded tip to achieve the same effect as in the case of FIG. There is.

That is, if the configuration shown in FIG. 2 is used, since the optical bidirectional repeater 10 can amplify the signal, communication can be performed even if the length of the optical fiber 3 is lengthened. Shoko two-way repeater 10
Even if it is inserted in the middle of the optical fiber 3, it becomes possible to lengthen the section of the optical fiber 3 and perform communication.

[0022]

As described in detail above, according to the present invention, since amplification can be performed by the optical bidirectional repeater 10, communication can be carried out even if the length of the optical fiber 3 is lengthened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a block diagram of a same-wavelength optical bidirectional communication system according to an embodiment of the present invention;

FIG. 3 is a block diagram of an optical bidirectional repeater according to an embodiment of the present invention;

FIG. 4 is a block diagram of an optical bidirectional repeater according to another embodiment of the present invention;

FIG. 5 is a block diagram of a conventional same-wavelength optical bidirectional communication system.

[Explanation of symbols]

1 and 2 are transmitting and receiving devices, 3 is an optical fiber, 4 and 5 are optical direct amplifiers, 4-1 and 5-1 are doped fibers, 4-2 and 5-2 are laser diode amplifiers, 6 and 7 are branch type optical 20 and 21 are optical transmitting sections, 22 and 23 are optical receiving sections, 30 and 31 are directional couplers, 40 is a pumping light source, and 41 is an excitation circuit.

Claims (1)

[Claims] Claim 1: Opposing transmitting/receiving devices (1, 2) that transmit and receive signals of the same wavelength are connected by an optical fiber (3), and the optical fiber is connected between the opposing transmitting/receiving devices (1, 2). (3) In a same-wavelength optical bidirectional communication system that performs communication using the same wavelength optical signal via the transmitter/receiver (1,
2) between the input side of the upstream optical direct amplifier (4),
The diagonally cut portion of the output side of the downstream optical direct amplifier (5) is connected with a branched optical fiber (6), and the input side of the downstream optical direct amplifier (5) and the upstream side A two-way optical repeater (10) connected to a diagonally cut portion of the output side of the optical direct amplifier (4) by a branch type optical fiber (7) is inserted. Communications system.