JP2824982B2 - Optical communication network connection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication network system, and more particularly, to an optical communication network system in which a plurality of networks using different optical wavelengths are connected.

2. Description of the Related Art Many local area networks (LANs) using optical fibers as optical signal transmission media use short optical wavelengths of 0.85 μm. However, recent technological advances have reduced transmission loss and reduced transmission distance. LANs using long 1.3 μm optical wavelengths that can be extended are gradually increasing. as a result,
Currently, LANs using different optical wavelengths coexist.

Conventionally, such an optical communication network system in which LANs with different optical wavelengths are used is connected as shown in FIG.
Short wavelength (0.85μm) ring-shaped LAN41 and long wavelength (1.3μm)
The configuration is such that the ring-shaped LAN 42 of FIG. The gateway device 43 performs a conversion process of a protocol and a communication mode up to a network layer in addition to the optical wavelength conversion.

However, according to the configuration in which LANs are connected by such a gateway device, each LAN is basically independent, and becomes a dual or multiple network system as a whole. When communication is performed between a node of one LAN and a node of another LAN, software control of the gateway device is indispensable, and control of the entire system becomes complicated, and the gateway device becomes expensive. was there.

The present invention has been made in view of the above problems, and has as its object to provide a unified communication network system constructed from a plurality of networks using different optical wavelengths without using an expensive gateway device. .

Although the purpose is different, the optical signal is converted into an electric signal, then converted into an optical signal of another optical wavelength, and a bidirectional transmission using a single optical fiber using optical means is enabled. An optical wavelength converter (Japanese Patent Application Laid-Open No. 62-104328) is known.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is to form a plurality of networks composed of optical fibers from which optical signals of a single wavelength are transmitted in a predetermined direction in series, and to form a ring as a whole. In a network connection method for connecting, in order to convert an optical wavelength received from one network to an optical wavelength used by a network connected to the other, a light receiving element that converts an optical signal into an electric signal, A light-receiving amplifier for performing waveform shaping of the electric signal, separating received data and a received clock, and a timing extractor for reproducing the received data and the received clock in the received-light amplifier and outputting the data as the transmitted data and the transmitted clock. A light having a wavelength used by a network connected in response to the transmission data and the transmission clock output by the timing extraction unit. A configuration is provided in which a plurality of networks having different wavelengths are connected to each other by using a light emitting unit that converts the light into a signal and emits light.

Effect of the Invention According to the present invention, the optical signal on each optical signal transmission medium is transmitted to the optical signal transmission medium of the connection partner network by the optical wavelength conversion means even if the used optical wavelength of each network is different due to the above configuration. Since it is converted into an optical signal of an optical wavelength and transmitted, communication between networks is possible. In addition, since the whole network is a ring-shaped unified network system, complicated software control as in the conventional system using the gateway device is not required.

Embodiment FIG. 1 shows a schematic configuration of an optical communication network system according to an embodiment of the present invention, in which 1 is a LAN having a short wavelength (0.85 μm), and 2 is a long wavelength (1.3 mm).
μm) LAN.

Each end of the optical fiber cable 3 which is an optical signal transmission medium of the two LANs 1 and 2 is connected in series by an optical wavelength converter 4 for converting a long wavelength to a short wavelength and an optical wavelength converter 5 for converting a short wavelength to a long wavelength. And a ring-shaped unified optical communication network system is constructed as a whole.

The optical wavelength converters 4 and 5 perform only optical wavelength conversion, and
2 is connected, and no conversion processing such as protocol is performed. Therefore, the optical wavelength conversion devices 4 and 5 can be realized at a much lower cost than the gateway device.

In such a configuration, when transmission is performed from the LAN1 node to the LAN2 node, the short wavelength optical signal transmitted from the former node is converted into a long wavelength optical signal by the optical wavelength converter 5 and transmitted to the LAN2. , Received by the latter node. In the case of transmission from the LAN2 node to the LAN1 node, the long-wavelength optical signal transmitted from the former node is converted into a short-wavelength optical signal by the optical wavelength converter 4, transmitted to the LAN1, and received by the latter node. . At the time of such optical communication, software control of each of the optical wavelength converters 4 and 5 is unnecessary.

FIG. 2 is a configuration diagram of an example of an optical wavelength converter used as the optical wavelength converters 4 and 5. The optical wavelength conversion device shown here includes a light receiving element 11, a light receiving and amplifying section 12, a timing extracting / identifying section 13, a light emission driving section 14, and a light emitting element 15.

Light receiving element 11 is an optical fiber cable connected to the input side
It converts an optical signal input from 3a into an electric signal. In this case, an APD (avalanche photodiode) is used.
A light receiving element such as an IN photodiode may be used.

The light emitting element 15 converts an electric signal into an optical signal and outputs the converted signal to the optical fiber cable 3b connected to the output side. Here, a laser diode (LD) is used, but another light emitting diode (LED) may be used. Naturally, the light emission wavelength of the light emitting element 15 is selected as the used light wavelength of the network using the optical fiber cable 3b as a medium.

The light receiving and amplifying section 12 is a section for shaping the waveform of the optical signal converted by the light receiving element 11, and includes a preamplifier 17, an AGC loop 18, an AGC amplifier 19, an offset canceller 20, and a main amplifier 21.

The timing extracting / identifying section 13 is a section for reproducing received data and a received clock from the signal after waveform shaping by the light receiving / amplifying section 12, and includes a mixer 23, a filter 24, and a limiter 25 for extracting the received clock. Data identification and reproduction circuit for reproducing received data based on a reception clock
It consists of 26. Each signal of the reproduced received data and the received clock becomes a signal of the transmitted data and the transmitted clock of the light emission drive unit 14.

The light emission driving unit 14 is a part that causes the light emitting element 15 to emit light according to the transmission data, and the NRZ / RZ conversion circuit 27, the light emitting element driving circuit 28, and the light emitting element driving circuit to stabilize the light output level of the light emitting element 15. Optical output control circuit that controls 28
It consists of 29.

When the optical wavelength conversion device having such a configuration is used as the optical wavelength conversion device 4 in FIG. After being converted into a signal and subjected to waveform shaping and timing correction, the light emitting element 15 uses the short wavelength (0.85μ
m) is converted to an optical signal and output side optical fiber cable 3b
Output to

It should be noted that an optical wavelength converter having a simplified configuration in which the timing extraction / identification unit 13 is omitted can be used. In addition, the optical wavelength conversion device may be provided with a circuit that detects reception interruption by monitoring a reception clock and controls an alarm or the like, or a circuit that detects an abnormality in the light output level of a light emitting element and controls an alarm or the like. It may be provided.

FIG. 3 is a schematic configuration diagram of an optical communication network system according to another embodiment of the present invention. The system uses light wavelength of lambda ₁ LAN 31, LAN 32 use light wavelength lambda _2, LAN 34 of an optical signal transmission medium LAN33 and used light wavelength of used light wavelength lambda ₃ is lambda ₄ (optical fiber cable) The optical wavelength converters 35, 36, 37, and 38 are connected in series to form a loop-shaped unified optical communication network system as a whole. Optical wavelength converters 35, 36, 37, 38 are the second
An apparatus as shown in the figure can be used.

Note that at least some of the LANs may use the same optical wavelength. For example, when λ ₁ = λ _4, a simple relay device that does not perform optical wavelength conversion can be used instead of the optical wavelength converter 38 for connecting the LANs 31 and 34. As the relay device, it is possible to use apparatus such as a device of the selected configuration lambda ₁ light emission wavelength of the light emitting element 15 in FIG. 2, or further omitting the timing extraction / identification unit 13 configured.

Effect of the Invention As is apparent from the above description, the present invention is for connecting a plurality of networks constituted by optical fibers,
By providing a conversion means for converting an optical wavelength received from one network into an optical wavelength used by a network connected to the other between the networks, without using an expensive gateway device, a plurality of optical wavelengths different from each other can be used. An integrated optical communication network system that enables optical communication between networks such as a LAN can be constructed. Further, since the reception data and the reception clock are once reproduced in the optical wavelength conversion unit and are output as the transmission data and the transmission clock, it is possible to easily manage a communication state or the like which is likely to occur when the networks are connected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical communication network system according to one embodiment of the present invention, FIG. 2 is a block diagram of an example of an optical wavelength converter, and FIG. 3 is an optical communication network system according to another embodiment of the present invention. FIG. 4 is a schematic configuration diagram of a conventional optical communication network system. 1, 2, 31, 32, 33, 34 ... LAN, 3, 3a, 3b ... optical fiber cable, 4, 5, 35, 36, 37, 38 ... optical wavelength converter, 11 ... light receiving element, 12: light-receiving amplifier, 13: timing extraction / identification unit, 14: light-emitting drive unit, 15: light-emitting element.

Claims (1)

(57) [Claims] In a network connection method for connecting a plurality of networks composed of optical fibers for transmitting optical signals of a single wavelength in a predetermined direction in series and as a whole as a whole, light is received from one of the networks. In order to convert an optical wavelength to an optical wavelength used by a network connected to the other end, a light receiving element that converts an optical signal into an electric signal, and a waveform shaping of the electric signal from the light receiving element is performed to receive data and receive data. A light-receiving amplifier that separates a clock, a light-receiving amplifier reproduces received data and a received clock, and outputs a transmission data and a transmission clock as a timing extractor; and a transmission data and a transmission clock that are output by the timing extractor And a light emitting unit that converts the light into a light signal having a wavelength used by the connected network and emits light, and Go signal to chromatography click, and by providing the one for the return, an optical communication network connection method characterized by connecting a plurality of networks together wavelengths.