JPH0362006A - optical transmission equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical transmission device in which an optical transmitter and an optical receiver are connected by a transmission optical fiber.

BACKGROUND OF THE INVENTION In conventional optical transmission equipment, an optical transmitter and an optical receiver are
It used a transmitting optical link and a receiving optical link that had light emitting power and light receiving sensitivity depending on the transmission distance. t, that is, when the transmission distance is long, the emitted light power is large on the transmitter side,
On the receiver side, a link with high light reception sensitivity was required.

Problems to be Solved by the Invention When the above-mentioned conventional long-distance optical transceiver was installed at a location where the transmission distance was short, the reception level was too high and the received signal was greatly distorted, making it impossible to transmit and receive correctly. .

A possible solution would be to install a level adjuster in all stages of the long-distance p-optical transceiver to lower the transmission and reception level when used over short distances. However, in reality, making a level adjuster that can change the level to adapt a long-distance one to a short-distance one would be extremely expensive because the level adjustment range is too large. It is.

Therefore, the present invention has developed an optical transmission system [Th
The purpose is to provide

Means for Solving the Problems In order to achieve this objective, the optical transmission device of the present invention has an optical transmission link and a relay optical fiber connecting the optical transmitter optical output part, and an optical receiver. At least one of the relay optical fibers connecting the optical input section and the receiving optical link is configured so that fibers with different core diameters or numerical apertures can be selectively used depending on the transmission distance.

Therefore, according to the present invention, when used for short distances, at least one of the relay optical fibers is made of gold having a core diameter smaller than that of the transmission optical fiber. If an optical fiber with a smaller numerical aperture than the transmission optical fiber is used as the relay optical fiber that connects the optical fiber for reception and the optical fiber for reception, a loss will occur between them and the optical fiber for transmission, resulting in the optical fiber for reception Correct transmission and reception can only be achieved by transmitting an optical signal at an appropriate level.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
The figure is a schematic diagram showing the configuration of an optical transmission device of the present invention.

In other words, in the optical transmission device of the present invention, the optical transmitter 1 is as follows:
It is composed of a transmission optical link 2, a relay optical fiber 4, and a relay adapter (light output section) 3 for coupling with the transmission optical fiber 5. In addition, the relay optical fiber 4 is
An optical fiber having a core diameter smaller than that of the transmission optical fiber 6 is attached. On the other hand, the optical receiver 6 includes a reception optical link 9, a relay optical fiber 8, and a relay adapter (optical input section) 7 for coupling with the transmission optical fiber 5. The relay optical fiber 8 has a core diameter smaller than that of the transmission optical fiber 5, or has a smaller numerical aperture.

When an optical fiber with a large core diameter or numerical aperture is connected to the direct transmission optical link 2, the incident power to the optical fiber is large, and excessive light is incident on the reception optical link 9, which distorts the signal and prevents the correct signal from being received. become unable.

First, in this embodiment, a configuration in which the optical transmitter performs pre-attenuation is adopted, and this configuration will be explained here. Figure 2 shows the LICD in the transmission optical link and the relay optical fiber 4.
FIG. Transmission optical link L
The light emitted from the ED enters the relay optical fiber 4. When the relay optical fiber is inserted into the optical transmitter 1,
Since the core diameter is small, the optical power taken in by the relay optical fiber 4 is small. That is, compared to the case where the core diameter is large, large attenuation occurs, appropriate optical power enters the receiving optical link 9, and a signal without distortion can be received.

Next, the connection structure between the optical receiver 6 and the relay optical fiber 8 will be explained with reference to FIG. The light emitted from the transmission optical fiber 6 is transferred to the relay optical fiber 8 as shown in FIG.
When entering the core, the light that protrudes from the core diameter enters the cladding section, becomes radiation mode light, and is not transmitted. Therefore, even if the output power of the transmission optical fiber 6 is large, it is attenuated when it enters the relay optical fiber 8, and the reception optical link 9
Appropriate light is incident on the

Next, the case where the numerical aperture is small will be explained with reference to FIG.

Among the light transmitted from the transmission optical fiber 5, after entering the relay optical fiber 8, the light that has a large propagation angle cannot propagate in the core and reaches the cladding layer, as shown in FIG. It turns into radiation mode and runs away. Therefore, as in the case where the core diameter is small, the light is attenuated, appropriate optical power is input to the receiving optical link 9, and a correct signal can be received.

Effects of the Invention According to the present invention, when used for short distances, at least one of the relay optical fibers has a core diameter smaller than that of the transmission optical fiber, and the first receiver input section If an optical fiber with a smaller numerical aperture than the transmission optical fiber is used as the relay optical fiber that connects the reception optical link, a loss will occur between them and the transmission optical fiber, and as a result, it is not suitable for the reception optical link. As a result, the optical signal of the correct rep N is transmitted, and correct transmission and reception are performed.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of an optical transmission device according to an embodiment of the present invention, Fig. 2 is a plan cross-sectional view showing the coupling state of a transmission optical link and a relay optical fiber, and Fig. 3 is a first receiver. Figure 4 is a cross-sectional plan view of the coupling state of transmission optical fibers with different core diameters and relay optical fibers with different core diameters. FIG. 2 is a cross-sectional plan view of a state in which a fiber and a relay optical fiber are coupled. 1... Optical transmitter, 4, 5.8... Optical fiber 9... Reception link.

Claims (1)

[Claims] an optical transmitter having an optical link for transmission; an optical receiver having an optical link for reception connected to the optical transmitter via an optical fiber for transmission; and an optical output section of the optical transmitter and the optical transmitter. At least one of the relay optical fibers that connect the optical receiver optical input section and the receiving optical link is a fiber with a different core diameter or numerical aperture depending on the transmission distance. Optical transmission equipment configured to connect.