JPS62291226A - Bidirectional optical communicating system - Google Patents

Abstract

PURPOSE:To decrease the number of parts of a device and to achieve a low power consumption by using a semiconductor laser as a light source for transmitting information and a wavelength selecting type light amplifying element. CONSTITUTION:Switches 18-1 and 18-2 are connected to a1 and a2 sides, information signals 19-1 and 19-2 are sent through a modulating circuit to semiconductor lasers 12-1 and 22-2, converted to the light signal of wavelengths lambda1 and lambda2 and inputted to a 1X2 port type light star coupler 14-1. The output of the coupler 14-1 is transmitted through an optical fiber 15 to a B station side. At the B station, a light signal is supplied through a star coupler 14-2 equal to an A station to semiconductor lasers 12-3 and 12-4. At such a time, respective semiconductor lasers 12-3 and 12-4 are connected to current supplying parts 21-3 and 21-4 and operated as the wavelength selecting type amplifying element of the wavelength lambda1, and the wavelength lambda2. By the reverse connection of the switch of respective stations, the transmission from the B station to the A station is executed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a bidirectional communication system for bidirectionally transmitting optical signals of a plurality of wavelengths within a single optical fiber.

[Conventional technology]

Wavelength multiplexing transmission technology in optical 7-aipa communications is extremely important for improving economic efficiency, for mutual information transmission, and for fully expanding functionality. In the wavelength division multiplexing transmission described above, the optical multiplexer/demultiplexer is a key device.

Conventionally, optical multiplexers/demultiplexers are composed of passive elements such as interference film filters and diffraction gratings (Yanai, Optical Communication Handbook,
Asakura Shoten, p324-p331゜1982), as well as
Recently, a method for configuring an active type optical multiplexer/demultiplexer that utilizes the gain distribution of a semiconductor laser diode as a demultiplexing function has been proposed ("Proposal of an optical multiplexer/demultiplexer using a laser diode", 1985 Electronic Communication Academic Society Semiconductor and Materials Division National University, A
365, pi-180).

FIG. 2 shows a configuration diagram of the active type optical multiplexer/demultiplexer. 1~
3 has an oscillation temporary length of 0.88. 1.3°1.55
With a μm semiconductor laser, these laser output lights are input into an optical star coupler (3 x 3 boats) and combined into one.

The above combined signal is divided into approximately 34 minutes and outputted to the output capo 11-1, 11-2, 11-3. and 5. laser diode amplifiers each having a different center wavelength. 6. 7. The center wavelength of laser diode amplifier 5 is 0.
．． Since it is 88 μm, when this amplifier 5 is on, it is 0.
．． The wavelength of 88 μm is amplified and output, and is received by the optical receiver 8. Optical signals with wavelengths of 1.3 μm and 1.55 μm are absorbed and not output. Similarly, since the center wavelength of the laser diode amplifier 6 is 1.3 μm, the optical receiver 9 receives an optical signal of 1.3 μm. Further, since the laser diode amplifier 7 has a center wavelength of 2i and is set to ss μm, an optical signal of 155 μm is received by the optical receiver 10. As described above, the optical star coupler 4 combines and splits the optical signals of each wavelength into one branch, and the laser diode amplifier of the desired center wavelength is used.

This method selects an optical signal of a desired wavelength and demultiplexes it.

This is an extremely effective method for demultiplexing optical signals whose wavelengths are sufficiently far apart.

[Problem that the invention seeks to solve]

By the way, the optical multiplexer/demultiplexer with the configuration shown in Figure 2 is for one-way communication, and considering two-way communication, a laser diode amplifier and an optical receiver are required on the transmitting side, and a semiconductor is also required on the receiving side. A laser is required. In other words, the number of active elements is very large.

Considering the current cost of optical fibers, there is a problem that the cost of passive elements is higher than that of a duplexer.Also, an electric circuit is required to drive all active elements, and the overall power dissipation is low. There is also the problem that the cost is also high.

The purpose of the present invention is to have a simple configuration with a small number of parts.

The objective is to provide a low-cost, low-power consumption bidirectional optical communication system.

[Means for solving problems]

The above object is achieved by the following configuration. That is, at least one
In a system that bidirectionally transmits optical signals of different wavelengths from upstream to downstream, both the upstream and downstream sides are equipped with a semiconductor laser and an optical receiver for each wavelength.

The semiconductor laser is used as a light source for information signal transmission.

Alternatively, a wavelength-selective optical amplification element is used to transmit an optical signal to an optical receiver, and is switched and driven by an electric switch.

[Effect]

The bidirectional optical communication system of the present invention focuses on the fact that a semiconductor laser has a function as an excavation light source and a wavelength-selective amplification element, and has invented a new system that combines both of the above functions. It is. That is, at times, the information signal is converted into light and transmitted as a light source with the desired wavelength λ, and at other times, the optical signal t with the desired wavelength λ1 is selectively amplified from among the transmitted optical signals. The semiconductor laser is operated by switching its driving mode (using a switch) so as to transmit light to the light receiving section. Therefore, in the case of one-wavelength bidirectional communication, each station may have a simple configuration consisting of a semiconductor laser, a light receiving section, an electric switch, a modulation circuit, and a current supply section.

〔Example〕

FIG. 1 shows an embodiment of the bidirectional optical communication system of the present invention. This is an embodiment of a system in which two-wavelength optical signals are transmitted bidirectionally between stations A and B. 12-1 and 12-3 are semiconductor lasers whose oscillation center wavelength is λ1. 12-2.12
-4 is a semiconductor laser whose oscillation center wavelength is λ=. The wavelength interval between λ凰 and λ2 is set to be large. For example, 1.2μm and 1.55μm% or 1.3μm and 1
．． It appears as 55μm. These semiconductor lasers 12
-1 to 12-4 are information signals 19-1゜19-
2. 19-3. 19-4t- Operates as a light source for transmission, and at times selectively passes the transmitted optical signal with a desired oscillation center wavelength, and operates as an optical receiver (13-1,
13-2, 13-3, 13-4) is configured to operate as a wavelength-selective optical amplification element.

First, the method of transmitting t7 information from the coterie side to the station B side will be described. Switch 18-1: ax 'A1Cm continuation.

・The g-report signal 19-1 is sent to the semiconductor laser 12-1 through the modulation circuit, converted to an optical signal (wavelength λ1), and transmitted to the transmission line 22-1.lX2 boat type optical star coupler 14-1.
The signal is transmitted through the optical fiber 15 and sent to the 1st station B side.

The switch 18-2 is also connected to the AL side, and the alarm signal 19
-2 to the wavelength λ heat and transmits it to the station B side.

On the station B side, the above anti-length λ1. 1x2 optical signals including light 1j of λ2! The optical star coupler 14-2 branches the optical transmission into two, a2z-3 and 22-4. Then, it is input to the semiconductor lasers 12-3 and 12-4. Here, if the switch 18-3 is connected to the kbs side and the switch 18-4 is connected to the b4 side, the semiconductor laser 12-3, 12-4 receives a current from the current supply parts 21-3 and 21-4. is supplied.

When an optical signal approximately equal to the oscillation center wavelength of each of the semiconductor lasers 12-3 and 12-4 is input, the optical signal is selectively amplified. .

Such light augmentation version 1 is, for example, "Electronics Letters (EleCtrOniC3Letters,
24th) May 1984, Vow, 20. /i
11. It is described on p438-p439J. Therefore, the wavelength λ! input to the semiconductor laser 12-3! ,λ
Among the optical signals of 2, the light with wavelength λl is selectively amplified and passes through the optical transmission line 23-31 &: to the optical receiver 13-3.
received at The optical signal is then converted into electricity and sent to the terminal 16-3, where the information signal 19-1 is extracted. Similarly, the wavelength λ input to the semiconductor laser 12-4
1. Of the optical signals of λ2.

The optical signal of λ2 is selectively amplified and sent to the optical transmission line 23-4.
．． An information signal 19-2 is taken out at the terminal 16-4 through the optical receiver 13-4. Note that the optical receiver 13-3.1
The circuit switching control signal included in the output signal of 3-4 is sent to the switch control units 17-3 and 17-4.

The switches 18-3 and 18-4 are controlled based on the output signals of these switch control sections 17-3 and 17-4. In other words, the signal transmission from the doujin side ends, and conversely, the signal transmission from station B ends.
When you want to transmit a signal from the station A side to the station A side, switch 18
The switch control units 17-3 and 17-4 output signals for connecting the switch 18-3 to the a3 side and the switch 18-4 to the a3 side.

Next, the case where an information signal is transmitted from the station B side to the station A side will be explained. The switch 18-3 switches from b3 to a3, the switch 18-4 switches from b4 to a4'Ic, and the information signals 19-3, 19-4 are respectively sent to the semiconductor lasers 12-3.
12-4 is converted into an optical signal, combined at an 1X2 boat type optical star coupler 14-2, and transmitted through the optical fiber 15.

On the station A side, the above-mentioned combined signal is branched into two by a 1x2 port type optical star coupler 14-1, and the optical transmission line 22-1.2 is split into two.
2-2, and is manually input to the semiconductor laser 12-1.12-2. In the semiconductor laser 12-1, the wavelength λ1. Lambda goose's light signal hammer.

The optical signal having the wavelength λ1 is selectively passed through and guided to the optical receiving section 13-1. Here, the optical receiver 13-1 converts the optical signal into an electrical signal, indicating that information has been sent from the station B side to the switch controller 17-1.

In response to the above instruction, the switch control section 17-1 issues a signal to switch to the switch 18-1eat (glass).

Note that the switching of the switch ts-i from al to bI may be performed automatically by a line switching control signal sent from the other party as described above.

Alternatively, it may be done manually.

When the switch 18-1 changes from al to bl.

A press-fit current is supplied to the semiconductor laser 12-1 from the four-current supply section 21-1, and among the optical signals inputted to the semiconductor laser 12-1, the optical signal with the wavelength λl is selectively amplified, and the optical signal is sent to the optical receiver 13. -1 optical transmission p! An optical signal of wavelength λl is input through 23-1. The output of the optical receiver 13-1 is sent to the terminal, and an information signal 19-3 is output. Similarly, the semiconductor laser 12-2 is also supplied with an injection current from the Ili solder supply section 21-2, and the optical signal of wavelength λ2 is selectively amplified. The optical signal is then converted into an electrical signal by the optical receiver 13-2, and the information signal 19-4 is reproduced from the terminal 16-2.

Note that the switch 18-1. 18-2. 18-3゜1
The switching control of 8-4 may be performed in a non-stop manner. For example, if you want to send information from the station B side to the station A side, the above switch switching control signal is included in the information signal 19-3.19-4 and transmitted to the station A side, and this switch switching control signal is optically received. It may be detected by the section 13-1.13-2 and sent to the switch control section 17-1.17-2. Just in case, if you want to switch to the switch 18-1t-at-glass, transmit the switch switching control signal to the information signal 19-4 from the 1st station B side, and receive it at the optical receiver 13-2. This signal may be sent to the switch control section 17-1 as indicated by a one-dot line 24-1. Similarly, when it is desired to switch from switch 18-3t't)s to a3, a switch switching control signal is included in the information signal 19-2 and transmitted, and the optical receiver 13-4 receives it, and the point 424
-2, the switch switching control signal may be sent to the switch control section 17-3.

Furthermore, an optical signal of wavelength λl is transmitted from the waste input side to the station B side.
It is also possible to transmit an optical signal with a wavelength λ2 from the station B side to the station A side, or transmit an optical signal with a wavelength λ2 from the station Ag1 to the station B side, and an optical signal with a wavelength λl from the station B side to the station A side. It is clear from the explanation so far that the information can be transmitted to the other side.

The invention is not limited to the above embodiments. First, the number of wavelengths multiplexed can be one, three, or more. 1×n
baud)! If a wavelength-dependent optical star coupler is used and it is given a certain degree of demultiplexing characteristics, higher isolation characteristics can be obtained. Also, instead of the optical star coupler 14-1, 14-2, a demultiplexer with simple demultiplexing characteristics (for example, a directional coupler, an 8tIi! type optical coupler) may be used.

etc.), it is possible to achieve high isolation characteristics in the same way as above. Optical transmission line 23-1 between the semiconductor laser and the optical receiver. 23-2゜23-3.23
-4 may be omitted and the semiconductor laser and the optical receiver may be integrally formed on the semiconductor substrate.

〔Effect of the invention〕

According to the present invention, by using a semiconductor laser at times as a light source and at other times as a wavelength-selective amplification element, two-way optical communication with a simple configuration, low cost, and low power consumption with a small number of parts is achieved. This has the effect of providing a method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of a bidirectional optical communication system that is an example of the present invention, and FIG. 2 is a block diagram showing the structure of a conventional active type optical multiplexer/demultiplexer. 1-3.12-1-12-4... Semiconductor laser, 4°14-1.14-2... Optical star coupler, 5-7...
・Laser diode amplifier, 8~10.13-1~13
-4... Optical receiver, 11-1 to 11-3... Output port, 15... Optical fiber, 16-1 to 16-4...
- Terminals, 17-1 to 17-4...Switch control unit. 18-1 to 18-4...switch, 19-1 to 19-
4... Information signal, 20-1 to 20-4... Modulation circuit. 21-1 to 21-4... Current supply section, 21-1 to 22
-4.23-1 to 23-4... Optical transmission line. ,.

Claims (1)

[Claims] 1. A method for bidirectionally transmitting an optical signal of at least one wavelength in the upstream and downstream directions using one optical fiber,
Both the upstream and downstream sides are equipped with a semiconductor laser and an optical receiver for each wavelength, and the semiconductor laser is used as a light source for information signal transmission,
Alternatively, a bidirectional optical communication system characterized in that a wavelength-selective optical amplification element is used to transmit an optical signal to an optical receiver and is switched and driven by an electric switch. 2. If the wavelength of the optical signal transmitted within one optical fiber is two or more waves, the semiconductor laser emitted light of each oscillation center wavelength is combined using an optical multiplexer and transmitted into the optical fiber. 2. The bidirectional optical communication system according to claim 1, characterized in that: 3. The bidirectional optical system according to items 1 and 2, characterized in that the switching control of the electric switch is performed by detecting a circuit switching control signal sent from the other station using the optical receiver of the own station and using the detection signal. Communication method.