JPS5819878Y2 - Two-way optical communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical communication device using an optical fiber as a transmission path, and particularly to an optical communication device that performs bidirectional transmission using a single optical fiber.

This type of device does not require two optical fibers for bidirectional transmission, so it has the advantage that the transmission path is economical.

As shown in FIG. 1, a conventional device of this type includes an optical transmitter 11. Optical receiver 21. Optical coupler 31. Detachable optical connector 51 connecting optical coupler 31 and single optical fiber 4
One station is equipped with an optical transmitter 12, an optical receiver 22, an optical coupler 32, and a removable optical connector 52 at the other station that is to perform bidirectional optical communication with the layer. The optical connectors 51 and 52 were connected by a single optical fiber 4.

Therefore, for example, when the transmitted light from the optical transmitter 11 passes through the optical coupler 31 and the optical connector 51, the optical connector 5
Due to the air layer present at 1, only a small portion of the transmitted light is reflected.

This reflected light is mixed with the transmitted light from the optical transmitter 12 and reaches the optical receiver 21 via the optical coupler 31.

That is, since the reflected light from the optical connector 51 that is received by the optical receiver 21 as noise light is so-called near-end crosstalk, the degree of attenuation is smaller than that of the signal light, which significantly deteriorates the signal transmission quality. .

Conventionally, methods to eliminate this drawback include: (1) using optical transmitters with different wavelengths and inserting a wavelength-selective filter immediately before the optical receiver; (2) inserting an optical isolator immediately before the optical receiver; ■Methods such as dividing the frequency of the electrical signal transmitted in both directions and inserting an electrical filter into the output of the first receiver are being considered.

However, methods ① and ③ above require expensive wavelength selective filters and optical isolators, and method ② requires a frequency conversion circuit and an electrical filter, making the circuit configuration complicated and expensive. It had

The present invention has a simple configuration that is expected to be significantly cheaper than conventional devices, and eliminates the reflected light from the optical connector of the transmitted light, thus achieving good transmission quality in both directions using a single fiber. To provide optical communication equipment.

Next, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 2, in one embodiment of the present invention, the optical transmitter 11 and the optical coupler 31 that are buttoned at one station, and the optical receiver 21 and the optical coupler 31 are detachable. They are connected via optical connectors 511 and 512.

In addition, the optical transmitter 12 and the optical coupler 32 of this station and the other station with which bidirectional optical communication is to be performed, and further between the optical coupler 32 and the optical receiver 22 are connected via detachable optical connectors 522 and 521, respectively. connected.

The optical coupler 31 and the optical coupler 32 are directly connected by a single optical fiber 4, and there is no optical connector or the like that would cause reflected light between them.

In this case, for example, the reason why a part of the transmitted light from the optical transmitter 11 is reflected and received as noise light by the optical receiver 21 is that depending on the characteristics of the optical connector 521 and the optical coupler 32, 522 is considered.

However, the level of the reflected light from these 521 and 522 has been considerably attenuated by the round trip transmission loss of the single optical fiber 4 before reaching the optical receiver 21, so the level of the signal light to the optical receiver 21 is In contrast, it is sufficiently small and allows high-quality signal transmission.

It should be noted that the optical couplers 31 and 32 and the optical fiber 4 do not need to be connected as shown in the figure at the manufacturing stage, and the very short optical fiber connected to the optical coupler 31 and 32 and the long-distance optical fiber can be connected to each other. 4 and 4 can be permanently connected by fusion bonding at the site where they will be used.

Since this connection method causes very little reflected light, the object of the present invention can be achieved.

One purpose of using removable optical connectors is to facilitate replacement of components in the event of failure, but optical couplers do not contain any active elements and are highly reliable. Therefore, even with the configuration of the present invention, an optical transmitter including an active element,
The optical receiver can be easily replaced as in the conventional configuration shown in FIG.

In this embodiment, such an optical connector is 2 times larger than that in Fig. 1.
However, the price for two optical connectors is the same as the wavelength selective filter used in the conventional method (2), the optical isolator used in the conventional method (2), or the frequency converter used in the conventional method (2). Cheaper than circuits and electrical filters.

As explained above, the present invention is significantly cheaper than conventional devices that use expensive optical isolators and wavelength selective filters to remove reflected light from optical connectors and have complicated electrical configurations. A high-quality single-fiber bidirectional optical communication device that can significantly reduce reflected light can be obtained with a simple configuration that can be expected to reduce the amount of light.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional bidirectional optical communication device, and FIG. 2 is a block diagram of an embodiment of the bidirectional optical communication device of the present invention. In the figure, 11 and 12 are optical transmitters, 21 and 2
2 is an optical receiver, 31 and 32 are optical couplers, 4 is a single optical fiber, 51, 52, 511. 512, 521 and 522 indicate detachable optical connectors.

Claims (1)

[Scope of utility model registration request] An optical transmitter, an optical receiver, and an optical coupler are provided at each of the two stations that are to perform two-way optical communication with each other, and the optical couplers of the two stations are directly connected by a single optical fiber, and each station's A bidirectional optical communication device characterized in that an optical transmitter and an optical coupler are connected by an optical connector, and an optical coupler and an optical receiver of each station are connected by an optical connector.