JP2709861B2 - Optical fiber communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an optical fiber communication device that uses optical fibers as transmission lines and performs single-fiber bidirectional communication without cutting the optical fibers.

[Prior art]

In an optical fiber communication device using an optical fiber as a transmission line, two-way communication using one optical fiber is desired for simplicity in operation. Conventionally, a wavelength multiplexing method and a frequency multiplexing method have been mainly considered as methods for realizing one-core optical fiber two-way communication. By the way, the biggest problem in the optical fiber communication device of the single-fiber two-way communication system is the effect of the reflected light at the end face of the optical fiber. Is masked. This is a major factor that limits the dynamic range of the optical fiber communication device. Frequency multiplexing uses light of the same wavelength for the transmission signals of both stations and uses different carrier frequencies, but uses light of the same wavelength. Cannot be optically isolated from the signal, and after conversion into an electric signal, isolation is performed by an electric filter. In this case, it is difficult to obtain an optical fiber communication device having a wide dynamic range because sufficient isolation cannot be obtained with only an electric filter. On the other hand, in the wavelength division multiplexing method, since lights of different wavelengths are used for the transmission signals of the respective stations, the transmission signals of the own station and the transmission signals of the other stations can be distinguished by the wavelength of the light. Thus, the influence of the reflected light of the own station can be removed. Therefore, conventionally, an optical fiber one-fiber bidirectional communication device is generally configured by a wavelength multiplexing method. In such a case, the transmission and reception of the optical signal to and from the optical fiber as the communication line are usually performed by the end-face incidence / end-face emission method with high coupling efficiency at both stations. Since the coupling efficiency is high in the end face incidence / end face emission method, the wavelength of the output light from each station in the case of the wavelength multiplexing method is arbitrarily determined.

[Problems to be solved by the invention]

However, if both stations adopt the end-face incidence / end-face emission method, when installing one station in the middle of the laid optical fiber, the optical fiber must be cut off at the installation location, and the There are problems such as the inability to use the optical fiber laid in the portion of the optical fiber and the difficulty in moving the installation location within the optical fiber laying range. SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber communication device that enables a communication device to be installed without cutting an optical fiber while enabling communication with a large dynamic range.

[Means for Solving the Problems]

In order to achieve the above object, an optical fiber communication device according to the present invention includes an optical fiber used as a transmission line, a communication device on one side installed at one end of the optical fiber, and an optional device in the middle of the optical fiber. And a communication device on the other side installed at a position, and the communication device on the one side has a transmission wavelength set to a wavelength commonly used for the optical fiber, and transmits a transmission light of this wavelength to an end face. It is configured to be incident on the end face of the optical fiber by the incidence method and to receive light emitted from the end face by the end face emission method,
The communication device on the other side has a transmission wavelength longer than the transmission wavelength on the one side, and a local injection device and a bending light receiving system for transmitting a transmission light of this wavelength to a bent portion of the optical fiber by a bending incidence method. And a local detection device for receiving the light leaking from the bent portion.

[Action]

A communication device on one side is connected to one end of an optical fiber used as a transmission line, and a communication device on the other side is connected to an arbitrary position on the optical fiber. The communication device on one side receives the transmission light having the wavelength commonly used for the optical fiber on the end face of the optical fiber by the end face incidence method and receives the light emitted from the end face by the end face emission method. It is configured. The communication device on the other side has a transmission wavelength longer than the transmission wavelength on the one side, and transmits the transmitted light of this wavelength to the bent portion of the optical fiber by a bending incidence method by a local injection device and a bending light receiving method. And a local detection device for receiving light leaking from the bent portion. As described above, since the communication device on the other side is provided with the local injection device and the local detection device of the bending incidence / bending light receiving method, the communication device is installed at an arbitrary position of the optical fiber without cutting the optical fiber. can do. The transmission wavelength of the communication device on one side of the end face incidence / end face emission method is the normal wavelength of the optical fiber, but the other side including the local injection device and the local detection device of the bent incidence / bend light reception type. Since the transmission wavelength of the communication device is longer than that, the coupling efficiency between the local injection device and the optical fiber is high. The coupling efficiency between the local detection device and the optical fiber in the other communication device is
The wavelength of the optical signal to be received and received from the communication device on one side is not so high because it is the normal wavelength of the optical fiber, but the communication device on the one side is of the end face incidence / end face emission type. Because of this, the coupling efficiency is high, and a large signal can be propagated through the optical fiber. With such a large signal, light can be easily received even in a state where the coupling efficiency is somewhat poor, and the dynamic range does not become narrow. Therefore, the dynamic range can be increased in both bidirectional communication.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, an optical fiber 1 forms a transmission line. In this embodiment, an end-face incident / end-face type telephone (master) 2 is connected to one end of the optical fiber 1 by a connector or the like. ing. The other handset (slave) 3 is attached to an arbitrary part of the optical fiber 1 via an adapter 4. Although not shown, the adapter 4 includes a local injection device and a local detection device. These local injection device and local detection device apply light of a light source from outside to a bent portion having a very small diameter provided to the optical fiber 1 to couple light into the optical fiber 1 or leak from the bent portion. It is a device for extracting light to the outside. When the adapter 4 is attached to the optical fiber 1, the optical fiber 1 is bent, so that the optical signal can be transmitted and received by the local injection device and the local detection device, and it is not necessary to cut the optical fiber 1. In this way, the base unit 2 and the slave unit 3 are connected via one optical fiber 1. Then, a call is made between the master unit 2 and the slave unit 3 by a wavelength multiplexing method. That is, the transmission wavelength from the handset 2 to the handset 3 is different from the transmission wavelength from the handset 3 to the handset 2. The transmission wavelength from the former handset 2 to the handset 3 is a wavelength commonly used for the optical fiber 1, and the latter is used as the transmission wavelength.
The transmission wavelength from the communication device 1 to the communication device 2 is longer than the former wavelength. For example, assuming that a single mode optical fiber for a wavelength of 1.3 μm is used as the optical fiber 1, the transmission wavelength of the base unit 2 is 1.3 μm, and the transmission wavelength of the slave unit 3 is 1.55 μm. In the bending incidence / bending light receiving method, generally, the further away from the cutoff wavelength, the stronger the optical coupling with the outside. Thus, by setting the transmission wavelength from the handset 3 to the base unit 2 to be longer, the local injection device can increase the coupling efficiency,
A wide dynamic range can be obtained. On the other hand, from the viewpoint of the coupling efficiency of the local detection device of the bending light receiving method in the handset 3, a longer wavelength is more desirable, but as described above, the wavelength of the transmission signal from the handset 2 is , The normal wavelength of the optical fiber 1. This is because the output optical signal is coupled to the optical fiber 1 by the incidence on the end face in the base unit 2 of the communication device, and the coupling efficiency is high. That is, the optical signal transmitted from the base station 2 propagates as a sufficiently large signal in the optical fiber 1. Therefore, it is easy to receive such a sufficiently large signal even if the coupling efficiency with the optical fiber 1 of the bending light receiving type local detection device in the handset 3 is not so high. is there. Therefore, as described above, the transmission wavelength from the handset 2 is set to the normal wavelength of the optical fiber 1 and the transmission wavelength from the handset 3 is set to a longer wavelength, thereby providing a wide dynamic range. Thus, two-way optical fiber communication can be performed.

【The invention's effect】

According to the optical fiber communication device of the present invention, the other communication device (slave device) can be installed at an arbitrary position of the optical fiber without cutting the optical fiber, and the one communication device (slave device) can be installed. The dynamic range can be increased in both the two-way communication between the parent device and the child device. That is, since the slave unit is configured to have the local injection device and the local detection device of the bending incidence / bending light receiving system, it can be installed at an arbitrary position of the optical fiber without cutting the optical fiber. Becomes In addition, the master unit uses an end-face incidence / end-face emission system, the slave unit uses a bent incidence / bend light-receiving system, and the transmission wavelength from the slave unit is longer than the normal wavelength of the optical fiber. The transmission light can be made incident on the optical fiber with efficiency, while on the other hand, the transmission light is made incident on the optical fiber by the end face incidence method on the parent device side, so that the coupling efficiency of receiving light by the bending light reception method at the slave device is reduced. An optical signal large enough to compensate for the badness can be propagated through the optical fiber. Thus, in one optical fiber one-way bidirectional communication using one optical fiber, the wavelength of the optical signal from the parent device to the child device and the wavelength of the optical signal from the child device to the parent device are made different. Communication with a large dynamic range can be performed in both directions.

[Brief description of the drawings]

FIG. 1 is a schematic view of one embodiment of the present invention. 1 ... optical fiber, 2 ... talk machine (master), 3 ... talk machine (child), 4 ... adapter.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masashi Matsuda 4-83-3 Shibaura, Minato-ku, Tokyo Inside Kandenko Co., Ltd. (72) Inventor Masao Tanaka 1440 Mutsuzaki Sakura City, Chiba Prefecture Inside the Sakura Plant (72) Inventor Yoshiharu Unami 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside the Sakura Plant, Fujikura Electric Wire Co., Ltd. References JP-A-2-21735 (JP, A) JP-A-62-18131 (JP, A) JP-A-55-145445 (JP, A)

Claims (1)

(57) [Claims] An optical fiber used as a transmission line,
A communication device on one side provided at one end of the optical fiber, and a communication device on the other side provided at an arbitrary position in the middle of the optical fiber, wherein the communication device on the one side has a transmission wavelength. The wavelength is a wavelength commonly used in the optical fiber, the transmission light of this wavelength is incident on the end face of the optical fiber by the end face incidence method and is configured to receive light emitted from the end face by the end face emission method, The communication device on the other side is
The transmission wavelength is longer than the transmission wavelength on the one side,
It is configured to include a local injection device for transmitting the transmission light of this wavelength into the bent portion of the optical fiber by the bending incidence method and a local detection device for receiving light leaking from the bending portion by the bending light receiving method. An optical fiber communication device, comprising: