JPS63167533A - Optical communication equipment - Google Patents

Abstract

PURPOSE:To apply switching to a standby line without interruption of communication and to monitor a transmission signal by providing an optical switch whose impressed voltage is controlled so as to switch a propagation path of an optical signal. CONSTITUTION:The optical switch is provided with polarized beam splitters 12a, 12b and full reflecting films 13a, 13b at each face of an electrooptic material layer 11 connected to a voltage application means 14. Without a voltage to the electrooptic material layer, the signal polarized wave to be transmitted is reflected totally and the signal light polarized wave reflected totally without any voltage impressed is transmitted. In this case, a signal light is radiated to a side different from the state impressed a voltage. In using the switch, part of the transmission signal is monitored and the standby line is switched quickly at failure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to technology in the field of optical communications. More specifically, the present invention relates to a new optical communication line configuration that allows line maintenance to be performed without interrupting communication.

Background of the Invention In recent years, communication systems using quartz-based optical fibers as transmission lines have been put into practical use, and even in Japan's public communication lines, high-capacity systems (F-400M) are used for relay communication lines.
) and small and medium capacity systems (F-32M, F-LOO
M) has already been put into practical use, and a 400 Mbs large capacity communication system has been put into practical use. Furthermore, in order to respond to the coming diversification of communication services, the introduction of optical communication systems to subscriber systems is being considered in the future.

By the way, as optical cables come to be substituted for copper cables such as coaxial cables, the establishment of maintenance techniques for optical signal lines becomes an important issue. In other words, when maintaining optical signal lines, it is necessary to use line switching technology such as switching from a working line to a protection line between subscriber terminals in an office, whether the working line is in use, or whether the line to be switched is correct. Line monitoring technology to determine whether or not this is the case will become inevitable.

Conventionally, such maintenance work has been performed by removing the connector at either end of the optical fiber cable and connecting it to a light receiver or a backup line.

Problems to be Solved by the Invention However, at the time of such monitoring or switching, communication using the line would be interrupted, so these operations could not be performed while the line was in normal use. .

Such situations in which communications are interrupted due to maintenance or repair work must be avoided at all costs, especially in subscriber-based communication lines, and unless these points are overcome, optical communication lines cannot be used for practical purposes. It cannot be applied to individuals.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the problems of the prior art described above and to realize a technique for monitoring or switching a communication line without interrupting the function of the communication line.

Means for solving the problem, namely, according to the invention, include selectable first and second outputs for one input, the first output being coupled to the main optical signal line, and the second output being coupled to the main optical signal line. An optical communication line comprising, at least one end of an optical signal line, an optical switch whose output can be coupled to another optical signal line, the optical switch converting an incident optical signal into a first polarized wave and a first polarized wave. a first polarizing beam splitter for separating into two polarized waves; a means for changing an optical path so that the first and second signal light polarizations intersect; and a means for transmitting the first and second signal light polarizations; an electro-optic material layer that rotates the plane of polarization of a transmitted light signal when a voltage is applied; and a second polarized light beam that is placed at the intersection of the first and second signal light polarizations that have passed through the electro-optic material layer and combines them. a splitter, and is configured to propagate an optical signal to the first and second outputs at an arbitrary rate by applying a voltage to the electro-optic material layer, and is configured to propagate an optical signal to the first and second outputs at an arbitrary rate, and to transmit the optical signal to the main optical signal line or the second output. An optical communication line is provided that is configured to emit an optical signal of an arbitrary proportion to at least one of arbitrary coupled signal lines without momentary interruption.

Operation Optical switches that can be suitably used in the communication line according to the present invention are as follows, for example. That is, the incident optical signal first enters the first polarizing beam splitter. At this time, if the first beam splitter is configured to totally reflect, for example, the S-polarized wave of the incident signal light and transmit all the P-polarized wave, each polarized wave of the incident optical signal will be mutually predetermined. They propagate in different directions at different angles.

Either one of these polarized waves is reflected by a total reflection film,
After allowing both side waves to propagate parallel to each other, they are transmitted through the electro-optic material layer. This electro-optic material layer is simply a transparent film when no voltage is applied, and transmits the incident optical signal as it is.

One of the signal light polarizations transmitted through the electro-optic material layer is changed in propagation direction by the total reflection film so as to be perpendicular to the other signal light polarization. Then, in a polarizing beam splitter placed at the intersection of both sides of the beam, one signal light polarization is transmitted as is, and the other signal light polarization is totally reflected. Therefore, by appropriately arranging the angle of this polarizing beam splitter, a signal light having substantially the optical power of the incident light is emitted in the propagation direction of the signal light polarization on the side that passes through the polarizing beam splitter.

On the other hand, when a predetermined voltage is applied to the electro-optic material layer described above, the plane of polarization of light transmitted through this layer is rotated. Therefore, with the above configuration, when a voltage is applied to the electro-optic material layer and the polarization plane of the signal light polarized wave transmitted therethrough is rotated,
The phenomena exhibited by each optical polarization at the polarization beam splitter on the output side are reversed. In other words, the signal light polarization on the side that was transmitted when no voltage was applied is totally reflected, and the signal light polarization on the side that was totally reflected when no voltage was applied is transmitted. . Therefore, in this case, the signal light is emitted to a side different from the one in which the voltage is applied.

Such an optical switch has no mechanical operating parts and can operate at high speed only by controlling voltage. Furthermore, by continuously changing the voltage applied to the electro-optic material layer, it is also possible to branch the incident optical signal at an arbitrary optical power ratio.

Therefore, by using this optical switch, the following optical communication line can be constructed. That is, by inserting this optical switch at at least one end of a predetermined section of a communication line, a part of the transmission signal can be taken out and monitored from the communication line in this section, or when a failure occurs, It becomes possible to replace the line with a spare communication line connected to the second output. Furthermore, since the optical switch operates quickly during these operations, communication using this line is virtually uninterrupted.

Furthermore, as mentioned above, when the backup signal line connected to the second output of the optical switch is used as a communication line, due to the configuration of the optical switch, it is necessary to apply voltage to the optical switch while the backup line is in use. There is.

Therefore, the use of the signal line connected to the second output is temporary, and while communication is secured through this backup line,
Preferably, the main signal line is replaced after a fault-free one, and communication is maintained using the main communication line connected to the first output of the optical switch.

EXAMPLES The present invention will be described in more detail below with reference to the drawings, but what is shown below is only one example of the present invention and does not limit the technical scope of the present invention in any way.

FIG. 2(a) is a perspective view conceptually showing the configuration of an optical switch that can be suitably used in a communication line according to the present invention.

This optical switch is connected to the electric and pressure applying means 14.
Polarizing beam splitters 12a, 12b and total reflection films 13a, 13 are provided on each surface of the electro-optic material layer 11, respectively.
b. However, the positional relationship between the polarizing beam splitter and the total reflection film is reversed between the input side and the output side of the optical switch, and the total reflection film is on the back side of the polarization beam splitter 12a with the electro-optic material layer 11 in between. 13b is
A polarizing beam splitter 12b is provided on the back surface of the total reflection film 13a.
is located. The polarizing beam splitter 12a is arranged at an angle of 45 degrees with respect to the incident signal light Lln, and the other total reflection films 13a, 13b and the polarizing beam splitter 12b are arranged parallel to this.

Figure 2 (b-o and (g-2)) are diagrams schematically representing the operation of the above-mentioned optical switch. The state shown in FIG. 2 (b-2) is called the non-operating state and the operating state.

First, the operation of the optical switch in the non-operating state will be explained.

The signal light Llh incident on the optical switch is first separated into S polarization and P polarization by the polarization beam subric 12a. At this time, the polarization beam splitter 12a is P
It acts to completely transmit polarized waves and totally reflect S-polarized waves.

Therefore, the P-polarized wave maintains the propagation direction at the time of incidence, travels straight, passes through the electro-optic material layer 11, and then passes through the total reflection film 13.
The propagation direction is changed by b, and the polarizing beam splitter 1
Propagates towards 2b. In order to clarify this point, in Figure 2, the S polarization is marked with "○" and the P polarization is marked with "11".
”.

On the other hand, the S polarized light is
After changing the propagation direction, the total reflection film 13a changes the propagation direction again, propagates parallel to the P polarized wave, passes through the electro-optic material layer 11, and then travels straight to the polarizing beam splitter 12b. reach.

In the polarizing beam splitter 12b, the S-polarized wave is totally reflected and the two waves are totally transmitted, as described above. Therefore,
The S-polarized light that has reached the polarization beam splitter 12b as described above is totally reflected, while the P-polarized light is completely transmitted. Therefore, both polarizations are superimposed to produce a signal light that is substantially equal to the input signal light. uL/. , f are output upward on the diagram.

Next, the operation of the optical switch in an operating state, that is, a state in which a voltage is applied to the electro-optic material layer 11, will be described. Note that the applied voltage at this time is a voltage at which the amount of rotation of the polarization plane of the transmitted light becomes maximum, that is, 90°.

Now, as shown in FIG. 2 (b-2), when the signal light Lie enters the optical switch in the operating state, as in the non-operating state, the P-polarized light is completely transmitted by the polarizing beam splitter 12a. S-polarized waves are totally reflected. Follow.

Therefore, the P-polarized wave maintains the propagation direction at the time of incidence and travels straight through the electro-optic material layer 11, and then passes through the total reflection film 13b.
The polarizing beam splitter 12 changes the propagation direction by
propagates towards b. However, in this case, the electro-optic material layer 11 is in a voltage applied state, and the P-polarized wave transmitted through the electro-optic material layer 11 rotates the plane of polarization by 90' to become S-polarized wave.

The S polarized wave is polarized at 90° by the polarizing beam splitter 12a.
After changing the propagation direction, the propagation direction is changed again by the total reflection film 13a, propagates parallel to the above-mentioned P polarized wave, passes through the electro-optic material layer 11, and then travels straight to reach the polarizing beam splitter 12b. do. At this time, the S-polarized wave is also changed to P-polarized wave by passing through the electro-optic material layer 11 in the operating state.

On the other hand, in the polarizing beam splitter 12b, the S-polarized light is totally reflected and the P-polarized light is completely transmitted, as described above. Therefore, in the signal light polarization converted into S polarization and P polarization as described above, contrary to the non-operating state, the S polarization separated from the input signal light travels straight, and the input signal The P-polarized wave separated from the light is totally reflected. Therefore, these superimposed output signal lights are directed to the right in the figure by LouL/
. It is emitted as 7.

In this way, this optical switch can change the propagation direction of light by controlling the voltage applied to the electro-optic material layer. Incidentally, by continuously changing the voltage applied to the electro-optical element, it is also possible to branch the incident light at an arbitrary optical power ratio.

As shown in FIG. 3, this 9-inch optical system is put into practical use by being housed in a case 31 and equipped with connector mounts at the entrance and two exit ports.

When an optical fiber was connected to the optical switch fabricated in this way via the connector 32 and a signal light whose optical power was measured in advance was input, the optical fiber connected to the output port via the connector 33 received an approximately 2 dB attenuated light. A signal was output. That is, the insertion loss of this optical switch was extremely small at -2 dB.

Moreover, when a voltage of 0.1 .mu. Furthermore, voltage terminal 3
When a voltage of 5 .mu.

FIGS. 1(a) to 1(C) schematically show the configuration of an optical communication line according to the present invention formed using the above-described optical switch.

FIG. 1(a) shows a communication line with the most basic configuration.

An optical switch P is provided at the input end of the signal line on the transmitting station A side,
A main signal line M is coupled to the first output of the optical switch P, a backup signal line S is coupled to the second output, and the main signal line M and the reserve signal line S are coupled near the output ends of these signal lines. After that, it is connected to the receiving station to form a communication line.

Therefore, if a failure occurs on the main signal line M, the output of the optical switch P can be switched to the backup signal line S side, and the line can be secured by the backup signal line ms.

However, in reality, with the above-described configuration, it is necessary to always install a backup signal line, which results in an increase in the weight of the cable. Therefore, as shown in Figure 1, etc., an optical mixer K with one of its input ends open is inserted into the end of the main signal line M on the receiving station B side, and the open input end is Provide a detachable connector. With this configuration, if there is a failure in the main signal line M or if it is necessary to inspect or maintain the main signal line M, the second output of the optical switch P and the opening of this optical mixer can be connected. A communication line can be secured by connecting the input terminal to the backup signal line S.

However, when the backup signal line S is used as a communication line,
Due to the configuration of the optical switch, it is necessary to apply a voltage to the optical switch P while the backup signal line S is in use. Therefore,
If there is a failure in the main signal line M, the use of the backup signal line S connected to the second output is temporary, and while ensuring communication through this backup signal line S, the main signal line
The main communication line M connected to the first output of the optical switch is used again. In this way, there is no need to continue supplying voltage to the optical switch for a long period of time. Furthermore, it is not necessary to always connect the backup signal line S, and it is sufficient to connect it only when necessary.

Furthermore, as shown in FIG. 3, optical switches P and Q can be provided at both ends of the main signal line. The replacement of the main signal line in this case is performed in the following steps. That is, the backup signal line S is connected to the vacant connector of each optical switch P, Q, and both optical switches are activated at the same time, thereby ensuring signal transmission through the backup signal line S. Subsequently, the main signal line M is replaced, the optical switches P and Q are rendered inactive again, and communication is performed via the main signal line. In such a configuration, the optical switch Q on the receiving side has no special meaning, but it is an effective configuration, for example, when a communication line is used for bidirectional signal transmission.

In addition, as a different way of using this line, an optical switch P
By appropriately adjusting the voltage applied to the main signal line M, only a part of the optical signal propagating through the main signal line M can be taken out to the auxiliary signal line S. Therefore, as shown in FIG. 1(C), for example, an optical power meter C is connected to the end of the backup signal line S opposite to the optical switch P, so that the communication line can be used without interruption of communication. It becomes possible to monitor the status.

Effects of the Invention As detailed above, the optical communication line according to the present invention is equipped with an optical switch that can extremely easily switch the optical signal transmission path by the simple operation of controlling the applied voltage.

Therefore, in a predetermined section of an optical communication line that is equipped with this optical switch at the end, it is extremely easy to monitor the transmission signal of this line or switch the line to a backup line, and it is also possible to interrupt the communication. It can be done without. This optical switch also has low insertion loss, so
There is also virtually no deterioration in signal quality due to the configuration according to the present invention.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (C) are diagrams schematically showing the configuration of an optical communication line configured according to the present invention, and FIG. FIG. 2(b-1) and (b-2) are perspective views showing the main configuration of an optical switch suitable for use in optical communication lines; FIG.
FIG. 2(b-1) is a diagram schematically representing the operation of the optical switch shown in FIG.
) is a diagram showing functions in an operating state, and FIG. 3 is a diagram showing the appearance of an optical switch actually manufactured using the members shown in FIG. 2(a). [Main reference numbers] 11... Electro-optic material layer, 12aS12b... Polarizing beam splitter, 13a,
13b - Total reflection H1 14... Voltage application means, 31... Case, 32.
33... Connector, 35... Voltage application terminal P, Q =... Optical switch + M... Main optical signal line S... Reserve signal line 11-39. Electro-optic 9 material longitudinal layer 12a, 12b・
...Polarization high-△ splitter 13a, 13t)...
・-・Total reflection antinode 14-・・Voltage application means Figure 1 Reference 8 of the drawing (no change in content) Procedural amendment (method) % formula % 2. Title of invention Optical communication line 3. Case of person making amendment Relationship with Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka Name (21
3) Sumitomo Electric Industries Co., Ltd. 4, agent address: 1-1o-77 Higashikanda, Chiyoda-ku, Higashikeito 101
, Contents of correction (1) Figure 1 Q))' is corrected to Figure 1 (d) as shown in the attached sheet. (2) Replace "ra)'" on page 19, line 2 of the specification with r (d
) J and corrected d''-', / l, 'n, · Ride - Procedural amendment (voluntary) 1. Indication of the case Patent Application No. 314031 of 1985 2
, Title of the invention Optical communication line 3, Relationship to the case of the person making the amendment Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka Name (213) Sumitomo Electric Industries, Ltd. 4, Agent address ■101 Tokyo 1-10- Higashikanda, Chiyoda-ku
76. Number of inventions increased by amendment (none) 7. Detailed explanation of the invention in the specification subject to amendment 8. Contents of amendment

Claims (4)

[Claims] (1) First and second selectable for one input
an output, the first output being coupled to a main optical signal line,
An optical communication line comprising, at least one end of an optical signal line, an optical switch configured such that the second output can be coupled to another optical signal line, the optical switch converting an incident optical signal into a first polarization. a first polarizing beam splitter that separates the polarized light into a polarized light and a second polarized light;
and an electro-optic material layer that transmits the first and second signal light polarizations and rotates the plane of polarization of the transmitted light signal when a voltage is applied. and a second polarizing beam splitter disposed at the intersection of the first and second signal light polarizations transmitted through the electro-optic material layer to combine them, 1 and a second output at an arbitrary ratio, the optical signal is configured to propagate at an arbitrary ratio to at least one of the main optical signal line or an arbitrary signal line coupled to the second output. An optical communication line characterized in that it is configured to emit an optical signal without momentary interruption. (2) The optical path changing means includes a first total reflection film disposed so that one of the signal light polarizations that has passed through the first polarization beam splitter propagates in parallel with the other, and the electro-optic material layer. 2. The optical communication line according to claim 1, further comprising a second total reflection film disposed so that one of the signal light polarizations is orthogonal to the other. (3) A main optical signal line having one end coupled to the first output of the optical switch and a second optical signal line having one end coupled to the second output of the optical switch transmit a transmission signal at the other end. The optical communication line according to claim 1 or 2, characterized in that the optical communication line is joined to each other so as to be combined. (4) The optical communication line according to claim 1 or 2, wherein the optical switches are provided at both ends of a predetermined section of the signal line so that they can be controlled simultaneously.