JPH02260837A - Optical ping pong transmission system - Google Patents

Abstract

PURPOSE:To attain bidirectional time division communication with one optical fiber and to expand a non-relay transmission range by connecting an optical fiber provided with an amplification function to both ends of the optical fiber constituting a transmission line and propagating a stimulating light in the same direction as the transmission direction of a communication signal light. CONSTITUTION:The system is provided with stimulating light generating means PA, PB generating a stimulating light with a prescribed wavelength, optical fibers FA, FB doped with the rare-earth material and selection means OA, OB leading selectively the stimulating light to any of coupling means CPA, CSA, CPB, CSB. At the reception, a communication signal light stimulated by a stimulating light and amplified while being led to the optical fibers FA, FB from the coupling means CPA, CPB is led to light-receiving means RA, RB via the coupling means CSA, CSB and at the transmission, the communication signal light stimulated by a stimulating light and amplified while being led to the optical fibers FA, FB from the coupling means CSA, CSB is sent to the optical fiber transmission line PF via the coupling means CPA, CPB. Thus, the bidirectional time division communication is applied by using only one optical fiber and the non-relay transmission range is expanded more than the case with using two optical fibers.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for communicating between communication parties connected to both ends of an optical fiber.
This invention relates to an optical ping-pong transmission system that performs bidirectional time-division communication.

[Prior Art] FIG. 3 shows a conventional system for communicating at the same wavelength between communication parties A and B using optical fibers.

In Fig. 3, 31 is a signal light source S provided on the communication party A side.
A and 33 are also light receiving systems, 32 is a signal light source SR provided on the communication party B side, and 34 is a light receiving system RB. The signal light source SA on the customer A side is one optical fiber 35.
The signal light source Sa of the communication party B side is connected to the light reception system RA of the communication party A side via another optical fiber 36. As described above, in the past, two optical fibers were required to perform bidirectional communication between communication parties A and B even when multiplexing was not performed.

[Problem to be solved by the invention] As mentioned above, in the conventional system, in order to perform bidirectional communication even when multiplexing is not performed, two optical fibers, which are more expensive than metallic cables, are required. However, if an electric amplifier circuit was used to extend the transmission distance and expand the range of applications, there were problems such as the need for a high-performance amplifier circuit in the receiving system. .

For this reason, it is important to consider the advantages of optical fiber cables, such as high-speed and high-bandwidth transmission, when using optical fiber cables for subscriber transmission lines that generally carry a small amount of traffic. was also constrained by economic considerations.

In addition, when using conventional electrical amplification circuits, if the transmission method is changed, it is necessary to make complex circuit changes in response to the change, and there are problems with flexibility when changing the transmission method. There were also problems with reliability due to the need to connect two optical fibers in each direction, which required sophisticated connection technology.

Therefore, an object of the present invention is to be able to perform bidirectional time-division communication using only one optical fiber as a transmission path.
Moreover, it is an object of the present invention to provide an optical optical transmission system that can extend the non-relay transmission distance or increase the transmission speed, has flexibility in changing the transmission system, and has improved reliability in optical fiber connection.

[Means for Solving the Problems] In order to achieve such an object, the present invention arranges a means for generating communication signal light and a means for receiving the communication signal light at both ends of an optical fiber transmission line. In an optical transmission system for direct communication, an excitation light generating means for generating excitation light of a predetermined wavelength, a second optical fiber doped with a rare earth material, and an optical fiber transmission line between the optical fiber transmission line and the second optical fiber. a first coupling means which is arranged and capable of selectively receiving excitation light and transmits communication signal light and excitation light propagated from the optical fiber transmission line toward a second optical fiber; The second optical fiber is disposed between the second optical fiber and the generating means, is capable of selectively receiving excitation light, and sends the communication signal light and excitation light generated by the generating means toward the second optical fiber. a second coupling means; and a selection means coupled to the excitation light generation means and selectively guiding the excitation light to either the first or second coupling means; The 8-signal light is guided to the second optical fiber, excited and amplified by the pumping light, and guided to the light receiving means via the second coupling means, and at the time of transmission, the signal light is transferred from the second coupling means to the second optical fiber. This is characterized in that the communication signal light guided by the pump light, excited by the pumping light, and amplified is sent out to the optical fiber transmission line via the first coupling means.

[Function] According to the present invention, optical fibers doped with a rare earth material are connected to both ends of one optical fiber constituting a transmission path between communicating parties in order to provide an amplification function at the optical signal stage. In addition, a communication start signal and a communication completion signal are inserted into the communication signal light, and control based on these signals switches the propagation direction of the pump light so that the pump light propagates in the same direction as the transmission direction of the communication signal light. Because of this, communication signal light can be amplified and communicated without using electrical amplification means, making it possible to extend the non-relay transmission distance or increase the transmission speed.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

An embodiment of the present invention is shown in FIG. Here, A is a communication party having a light emitting source SA, a light receiving system RA, a directional coupler DCA, and a controller CA, and B is a communicating party having a light receiving system RB and a light receiving system S6.
, a directional coupler DC8 and a controller CI. The light emitting source SA sends a communication start signal oAs b
A light source that generates a communication optical signal OA in a format including a communication signal OAT and a communication completion signal OAE, and a light source SR
Similarly, a light source generates a communication optical signal 08 having a format including a communication start signal OSS_S communication signal 01IT and a communication completion signal ORE. These light sources SA and S
The communication optical signal generated by B is received by light receiving systems Ra and RA provided corresponding to the other party. The directional coupler DCA couples the optical signal from the light emitting source SA to the transmission line side and the optical signal from the transmission line side to the light receiving system. Similarly, the directional coupler DC sends the optical signal from the light source S8 to the transmission line side.
The optical signal from the transmission line side is coupled to the light receiving system R6.

The controller CA controls the optical switch O5A in response to the transmission and reception of the communication light No. 43, and controls the excitation light source P, which will be described later.
Pumping light P when transmitting and receiving a communication optical signal at A
. A and PRA are switched. A controller C [l is an optical switch O5] installed in communication party B for the same purpose.
8, and the excitation light P from the excitation light source P6. 6 and PR
8. PA is the excitation light P having a wavelength of 1.43 μm, for example, at the communication party A side during transmission. A is input to the ESA2 terminal of the Cobra CSA through the optical switch O5A, and at the time of reception, the excitation light PRA with a wavelength of 1.5 μm, for example, is input to the optical switch O.
5A is an excitation light source that enters the EPA3 terminal of the CPA, and P6 is an excitation light source that enters the EPA3 terminal of the Kabra CPA at the communication party B side. Similarly, during transmission, P6 transmits excitation light F'oa with a wavelength of 1.43 μm to the optical switch O5.
This is an excitation light source that inputs excitation light PRIII with a wavelength of, for example, 1.5 .mu.m to the EPa3 terminal of the coupler cpB via the optical switch O5B. Kabra CSA on communication party A side
There is an optical fiber FA between the ESAI terminal of the Cable CPA and the EPA 1 terminal of the Cobra CPA.
An optical fiber FB is connected between the ε5IS1 terminal of a and the EPal terminal of the converter cpa. These optical fibers FA and FB are connected to provide an amplification function at the optical signal stage, and are optical fibers doped with a rare earth material, such as erbium Er+3. An optical fiber OF for optical signal transmission is connected between the EPA2 terminal of the Cobra CPA on the communication party A side and the EPIS2 terminal of the Cobra CPIII on the communication party B side.

FIGS. 2(A) to 2(G) are diagrams illustrating the operation of the embodiment shown in FIG. 1. The same reference numerals in FIG. 2 are used for the same parts in FIG. 1.

The operation of the embodiment will be described below using FIG. 1 and FIGS. 2 (8) to (G).

FIG. 2(A) shows a state in which communication is not taking place between communicators A and 8. FIG. On the communicating party A side, excitation light Tn
Excitation light PRA with a wavelength of 1.5 μm, for example, from P A is inputted from the EPA3 terminal of Cobra Cp^, and on the communicating party B side, excitation light PRA with a wavelength of 1.5 μm, also from the excitation light source PI, is input to
The excitation light PRO of m is input from the EPB3 terminal of the coupler ('PR).

FIG. 2(B) shows the case where the communication party A sends a signal to the communication party A. First, the excitation light source PA to the EPA3 of the cabra CPA is
The excitation light PRA from the excitation light source PA is blocked, and the excitation light P having a wavelength of 1.43 μI, for example, is emitted from the excitation light source PA. A is Kabra C5A E
S A 2 O't4 0th order light emitting source SA incident on the
The communication start signal OAS of the communication optical signal 0^ (=communication start signal OAs+communication signal OAT+communication completion signal 0AE) is input from the ESA3 terminal of the Cobra C5A. In this case, within the optical fiber FA, the excitation light POA and the communication start signal OAS travel in the same direction, so that the communication start signal OAs is amplified, and the optical fiber cable 11. Cobra CP6 + passes through optical fiber FIS and Cobra C3lI and reaches the light receiving system Ra of communication party B. Since the excitation light P□・ is also incident on the communication party B side from pump light #tP a, In the communication start signal OA
Since the propagating optical signal oAs' of S and the pumping light PRB propagate in the same direction, the signal oAs' is amplified. The amplification in the optical fibers FA and F6 is the communication optical signal OA? The same process is performed for the communication completion signal 0■.

FIG. 2(C) shows a case where the communicating party A ends the communication,
First, a communication completion signal oA! is sent from the light emitting source SA! After sending out the communication optical signal OA from the light emitting source SA and the excitation light P from the excitation light source PA. Next, the pump light PRA from the pump light source PA is input to the EPA3 terminal of the converter CPA so that the communication optical signal from the communication party B can be amplified and received.

FIG. 2(D) shows the operation of the communication party B side when receiving the communication completion signal 0゛1 from the communication party A, and shows that the excitation light PRfl from the excitation light source P is incident on the Epas@ child of the cabra cpa. and excitation light P. 8 into Esa2@ of Kabra CSa in preparation for sending out the communication optical signal OIS from the light emitting source S8.

FIG. 2(E) shows a case where communicator B sends a signal to communicator A, and corresponds to the case where communicator A side and communicator B side are swapped in FIG. 2(B). Similarly, FIG. 2(F) shows a case where party B ends the communication, and corresponds to FIG. 2(C), and FIG. 2(G) shows the communication completion signal 0° from party B. BE
Figure 2 (D) shows the operation of communication party A during reception.
corresponds to The explanations for these FIGS. 2(E) to 2G) are the same as those for FIGS. 2(B) to D) described above if symbols A and B are replaced, so the explanation will be omitted.

Here, if communicator B does not continue communication in the state of FIG. 2(D) and if communicator A does not continue communication in the state of FIG. 2(G), Return to state.

[Effects of the Invention] As is clear from the above, according to the present invention, bidirectional time-division communication can be performed only by using one optical fiber, and the communication optical signal can be amplified within the optical fiber. Since communication is carried out in this manner, the non-repeater transmission distance can be expanded compared to the conventional case of using two optical fibers. If the present invention is applied to the same transmission distance range as the conventional one, the bit rate can be increased commensurate with the amplification within the optical fiber, and the bit rate can be increased to compensate for the amplification within the optical fiber. It is also possible to shorten the burst period to perform higher-speed transmission.

Furthermore, as mentioned above, the present invention provides an amplification function at the optical signal stage and does not use an electrical amplification circuit, so even when changing the transmission method, it is not necessary to make complicated circuit changes. This allows us to respond flexibly to such cases.

Furthermore, compared to the case of bidirectional transmission using two optical fibers, it is possible to effectively utilize the optical fiber lines in the same optical fiber cable. For example, one of the two optical fibers is saved. It becomes possible to provide another optical transmission system according to the present invention using an optical fiber, or to use it as a backup line to improve the reliability of the transmission line.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
A) to (G) are diagrams for explaining the operation of the embodiment of the present invention, and FIG. 3 is a diagram for explaining the conventional system. ^, B...Communicator, OCA, DCa...Directional coupler, sa, sa...Light emitting source, RA, RB...Light receiving system, CA, C,...Controller, P^, pa...Excitation light source, osA, osB...Optical switch, C! Arc! ! Is '''Cabra, CPA+CPB...Cabra, F^, Fll...Optical fiber doped with rare earth material, OF...Optical fiber, ESA l~ESA3'...Cabra C5AEPA l~
EPA3...Cabra CPAES81~ESB3...'
Kabra C5aEpffil~EPB3... Kabra cp
Terminal a, terminal , terminal , terminal . Communication, ft, $B (jl

Claims (1)

[Claims] 1) In an optical transmission system in which a means for generating a communication signal light and a means for receiving the communication signal light are disposed at both ends of an optical fiber transmission line to perform bidirectional communication, excitation light of a predetermined wavelength is provided. excitation light generating means; a second optical fiber doped with a rare earth material; disposed between the optical fiber transmission line and the second optical fiber; and capable of selectively receiving the excitation light. a first coupling means for sending the communication signal light and the excitation light propagated from the optical fiber transmission line toward the second optical fiber; the second optical fiber and the generating means; a second optical fiber, which is disposed between the optical fiber and the optical fiber, and is capable of selectively receiving the excitation light, and transmits the communication signal light generated by the generation means and the excitation light toward the second optical fiber. a coupling means coupled to the excitation light generation means and configured to direct the excitation light to the first
and a selection means for selectively guiding the light to either one of the second coupling means, and when receiving, the light is guided from the first coupling means to the second optical fiber and is excited and amplified by the excitation light. The communication signal light is guided to the light receiving means via the second coupling means, and at the time of transmission, it is guided from the second coupling means to the second optical fiber, where it is excited and amplified by the excitation light. 1. An optical ping-pong transmission system, characterized in that said communication signal light is sent to said optical fiber transmission line via said first coupling means.