JPH05114884A - Active and reserve switching device - Google Patents

Abstract

PURPOSE:To smoothly switch the active and reserve devices by making minimizing the scale of hardware without deteriorating the original speed of light. CONSTITUTION:An optical signal synthesizing branch means 24 synthesizes the light frequency digital signal of a plurality of channels distributed to a plurality of branches. A reserve light frequency channel setting means 25 seas the active light frequency channel to be switched and outputs an optical signal. A light delay difference compensation means 27 compensates the difference of delay of the light frequency channel setting means 25 for active and reserve devices to be switched based on the delay difference compensation control signal of a light delay difference detection control means 29. The light delay difference detection control means 29 detects the difference of bit phase of the optical signal system outputted by the light delay difference compensation means 27 based on the output of the light branch means 28 and outputs a changeover control signal when the phase is matched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an active standby switching device for optical frequency multiplex communication. In particular, a current standby switching device that performs channel switching by converting a plurality of channel signals into frequency-multiplexed signals without converting an optical signal into an electrical signal, compensates for a delay difference between current standby optical transmission lines, and switches without interruption. It is about.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing the configuration of a digital optical transmission device in which a conventional standby switching device is used.
FIG. 9 is a block diagram of a cross-connect device on the transmission side of a digital optical transmission device in which a conventional active switching device is used. FIG. 10 is a block diagram of a cross-connect device on the receiving side of a digital optical transmission device in which a conventional active switching device is used. FIG. 11 is a block diagram of a transmission line changeover switch of a digital optical transmission device in which a conventional active spare switching device is used. FIG. 12 is a diagram for explaining a frequency multiplexing method of a conventional optical frequency multiplexing transmission system.

In FIG. 8, in the transmitting side transmission apparatus 1A,
First, a digital transmission signal sequence from a plurality of input signal sources time-division-multiplexed at a transmission rate of 155.52 Mb / s, which is composed of a frame of 125 μs time length unit, is transmitted by the cross-connect device 2A on the transmission side to, for example, 1. 544M
After speed conversion to b / s, this 1.544M
Line editing is performed based on network management information and operation information set in advance in b / s subframe units. After the edited digital signal sequence is time-division-multiplex-converted again to, for example, 622.08 Mb / s by the high-speed multiplexer-converter 3A in each path unit in the multiplexer 9A,
The data is sent to the working optical transmission line 7 via the transmission side switch 4A on the transmitting side and the interface circuit 5.

In the receiving side transmission device 1B, the working optical transmission line 7
Signal is received by the interface circuit 6, and the demultiplexing device 9B performs high-speed demultiplexing conversion for each path or line on the high-speed demultiplexing device 3B via the transmission path changeover switch 4B on the receiving side. After that, the receiving side cross-connect device 2B performs line editing in the same procedure as the transmitting side cross-connecting device 2A in the transmitting side transmitting device 1A, and outputs a digital signal sequence to the output end.

At this time, a digital signal is input to the cross-connect device 2A of the transmission device 1A on the transmission side, and a multiplexer 9 is provided.
A between the A and the transmission line changeover switch 4A, the working optical transmission line 7,
Between the transmission path changeover switch 4B and the demultiplexing device 9B in the receiving side transmission device 1B and the cross-connect device 2
The digital signal output from B is constituted by an optical line. At this time, the optical signal between the devices and the optical transmission line is subjected to optical intensity modulation. For example, "0" of the digital signal is associated with "off" of the light, and "1" is associated with "on" of the light. There is.

When a failure of the optical transmission line or a failure of the transmission device occurs in the working optical transmission line 7 of such a conventional digital optical transmission device, it is necessary to suspend the device for maintenance of these. The working optical transmission line 7 is temporarily switched to the standby optical transmission line 8 by the transmission line changeover switches 4A and 4B. Further, when the spare optical transmission line is used again as the working optical transmission line after the restoration of the failure, the transmission line changeover switches 4A and 4B are used to switch back.

Next, a conventional example of the cross-connect devices 2A and 2B and the transmission path changeover switches 4A and 4B will be described with reference to FIGS. In FIG. 9, the input to the cross-connect device 2A on the transmission side is, for example, 155.52 Mb /
s digital time division multiplexed optical signal train 10A, 10B,
10C undergoes photoelectric conversion by the input interface 11 and is once replaced by a digital pulse train of an electric signal. Next, these digital pulse trains are obtained, for example, from the Institute of Electronics, Information and Communication Engineers, Journal (B) J69-B, 2, pp13.
9-146 (S61-02) Path editing and line editing are performed in a unit of a predetermined time slot by the method as shown in "Three-stage switch network rearrangement algorithm". The outline is as follows. The digital pulse train of this electric signal becomes a unit of cross-connect (this is called a cross-connect time slot). For example, the cross connect circuit 13 on the transmitting side converts the time slot into an appropriate bit rate for each time length unit of 1.544 Mb / s, for example, the Institute of Electronics, Information and Communication Engineers, September 1988, pp 934-. 943
Time slots are exchanged by the T + T-S-T switch circuit configuration as shown in FIG. 4 of "Trend of Digital Cross-Connect Technology", and the digital time-division multiplexed optical signal trains 14A, 14B and 14C are obtained. After the time slot is set to a desired line or path, it is sent to the multiplexer 9A corresponding to each line or path. On the other hand, as shown in FIG. 10, the cross-connect device 2 of the receiving-side transmission device 1B
In B, the signal from the demultiplexing device 9B is processed by the cross-connect demultiplexing / converting circuit 16 after performing path editing and line editing in a predetermined time slot unit by the same procedure as the transmitting side cross-connecting circuit 13. Time slot 10 after demultiplexing and electro-optical conversion
The final configuration is D, 10E, 10F.

Further, in FIG. 11, the transmission line change-over switches 4A and 4B realize switching and switching back and forth between the working optical transmission line 7 and the standby optical transmission line 8, for example.
That is, first, the terminal 21 of the transmission path changeover switch 4A on the transmission side is the terminal 21A and the transmission path changeover switch 4 on the reception side.
The terminal 22 of B is connected to the terminal 22A,
Communication by the working optical transmission line 7 is performed via the electro-optical conversion circuit 60. At this time, the receiving side has a delay compensating circuit 19A using, for example, an electric memory for guaranteeing a delay difference between the optical transmission lines which will be described later.
It is assumed that 9A is arranged so that a signal from the optical transmission line can store a digital signal for a certain fixed length of time. Next, the following procedure is used to switch to the standby optical transmission line 8. First, the terminal 21 on the transmitting side is connected to the terminal 21B at the same time as the terminal 21A so that the signal is propagated in parallel to the working optical transmission line 7 and the standby optical transmission line 8. At this stage, a signal from the same signal source at the terminal 21 that has passed through both the optical transmission line 7 for the working and the optical transmission line 8 for the standby is transmitted to the terminals 20A and 20B of the transmission line changeover switch 4B on the receiving side. To be able to detect. Here, the working optical transmission line 7
With respect to the signals of and the auxiliary optical transmission line 8, the respective signals are temporarily stored in delay compensation circuits 19A and 19B using an electric memory, for example. This memory controls the stored time-series information by an external address to an arbitrary address.
It is a circuit that can take out the information stored in this address by designating, and can be realized by using an elastic store memory. A delay difference compensation detection circuit 20 which detects a delay difference between the transmission lines at the terminals 20A and 20B detects a relative delay time τ that is an integral multiple of the bit interval of the time series information. Furthermore, the delay compensation circuit 19 is delayed by τ detected by the delay difference compensation detection circuit 20.
The timing of signal reading from A and 19B is adjusted. Therefore, after switching to the standby optical transmission line 8, it is confirmed that the information of the multiplexed optical signal sequence is in a state of neither overlapping nor missing, and after connecting the terminal 22 to the terminal 22A and the terminal 22B simultaneously, the terminal 21A By disconnecting the terminal 22A, non-instantaneous switching is realized. At this time, the transmission device 1 on the transmission side
The transmission line changeover switch 4A of A has only a switching function, and the transmission line changeover switch 4B on the receiving side has the non-instantaneous interruption function of delay compensation accompanying the switching of the working spare.

The above-mentioned digital optical transmission device is a transmission system by optical intensity modulation in which a digital signal "0" or "1" is transmitted corresponding to "on" or "off" of light, and a large number of respective information is transmitted. The bit sequence of the digital signal from the source channel is time-division multiplexed (TDM: Time Division M) for superimposing at high speed by superimposing in the time direction.
This is a multiplex transmission method. On the other hand, separately from this, as an optical multiplex transmission system, each channel of an information source is assigned to an optical frequency, and the optical frequency multiplexing (FDM) is carried out after the optical frequency multiplexing.
Ion Multiplexing) transmission method. As shown in FIG. 12, this is because carrier frequencies ωn (n = 1, 2, 3,
...) is assigned to, for example, one channel of one digital information source of frequency ωn by frequency shift keying (FSK) as shown in "Coherent Optical Communication", Chapter 4, page 26 of the Institute of Electronics, Information and Communication Engineers. The digital signal “0” is assigned to ωn−f1, and “1” is assigned to ωn + f1 (fi is set to a frequency near ωn so that they do not affect each other between channel frequencies ωn), for example, a laser diode. Is performed, the channel frequencies ωn subjected to the plurality of modulations are multiplexed, and a large number of channel information sources are transmitted through one optical transmission line.

[0010]

However, in such a conventional active spare switching device as described above, the cross-connect devices 2A and 2B and the transmission line changeover switches 4A and 4B are provided in the transmission device as shown in FIG. Although the interface between each device is optically connected, the cross-connect and transmission path switching in the device are processed after being converted into an electrical signal, and the interface of the opto-electrical signal converter or the electro-optical signal converter etc. There is a problem that a circuit is required and the hardware scale becomes large. Further, when the cross-connect device and the transmission path changeover switch are configured by an electric circuit, the digital signal processing speed of the electric circuit cannot keep up with the high speed of the optical signal transmission, so the electric circuit can be processed at a low speed. There is a problem that the digital speed conversion of is required.

On the other hand, even in the optical FDM transmission system, when an attempt is made to add a cross-connect function or a transmission line switching function to a transmission device, the conventional technique has no choice but to rely on processing by an electric circuit. There is a problem in that an interface circuit for low-speed conversion, opto-electric conversion, electro-optical conversion, etc. is required, and the high speed inherent in light must be sacrificed in the transmission device. Furthermore, light F
When high-speed signal transmission is performed such that the transmission bit rate per channel in the DM transmission system exceeds several tens of Gb / s, there is a problem that processing by an electric circuit is limited.

The present invention solves the above problems,
To provide a working standby switching device capable of minimizing a hardware scale without converting an optical signal into an electrical signal and capable of switching a working standby without interruption without impairing the original high speed of light. With the goal.

[0013]

SUMMARY OF THE INVENTION According to the present invention, in an active standby switching device in which an optical transmission line is redundantly configured and a part of the optical transmission line is in a standby state for standby, an optical frequency digital signal of a plurality of channels to be input is input. An optical signal synthesizing / branching means for synthesizing a signal into an optical frequency multiplexed signal and distributing the optical frequency multiplexed signal to a plurality of branches, and a predetermined optical frequency channel is set for each of the plurality of branches. It is characterized by comprising a plurality of optical frequency channel setting means for selecting optical signals from a plurality of branching branches, and output terminals for outputting the outputs of the plurality of optical frequency channel setting means respectively to the optical transmission line.

According to the present invention, the optical frequency channel is set based on a delay difference compensation control signal which is inserted between at least two optical frequency channel setting means for setting the optical frequency channel to be switched and the corresponding output terminals. An optical delay difference compensating means for compensating the delay difference of the output of the setting means, and an optical branching means inserted between the optical delay difference compensating means and the corresponding output terminal for branching the output of the optical delay difference compensating means. , Detecting the bit phase difference of the optical signal series output by the optical delay difference compensating means based on the output of the optical branching means, outputting the delay difference compensating control signal, and outputting the switching control signal when the bit phases match. And an optical delay difference detection control means.

Further, according to the present invention, an optical separating / connecting means is inserted between the optical branching means and an output terminal corresponding to the optical branching means, and the optical branching means and the corresponding output terminal are separated and connected based on the switching control signal. Can be provided.

[0016]

The optical frequency digital signals of a plurality of channels input by the optical signal combining / branching means are combined into an optical frequency multiplexed signal and the optical frequency multiplexed signal is distributed to the plurality of branch branches. A plurality of optical frequency channel setting means sets a predetermined optical frequency channel for each of the plurality of branch branches, selects an optical signal from the plurality of branch branches, and outputs the selected optical signal to the output terminal. Also, based on the delay difference compensation control signal input by the optical delay difference compensating means inserted between at least two optical frequency channel setting means for setting the optical frequency to be switched and the corresponding output terminals, the optical frequency channel setting means Compensate for output delay difference. An optical branching means inserted between the optical delay difference compensating means and the corresponding output terminal branches the output of the optical delay difference compensating means, and an optical delay difference detection control means based on the output of the optical branching means. It is possible to detect the bit phase difference of the optical signal series output by the optical delay difference compensating means, output the delay difference compensation control signal, and output the switching control signal when the bit phases match. Further, the optical separation / connection means inserted between the optical branching means and the corresponding output terminal can be connected / disconnected based on the switching control signal.

As described above, it is possible to minimize the hardware scale without converting an optical signal into an electrical signal, and to switch the working spare without interruption without impairing the original high speed of light.

[0018]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an active backup switching device according to the first embodiment of the present invention.

In FIG. 1, the active standby switching device has an input terminal 23 for inputting optical frequency digital signals of a plurality of channels and optical frequencies λ1 to λ from the input terminal 23.
5, an optical signal synthesizing / branching means 24 for synthesizing the optical frequency digital signal of 5 into an optical frequency multiplexed signal and distributing the optical frequency multiplexed signal to a plurality of branch branches, and a predetermined optical frequency for each of the plurality of branch branches. A plurality of optical frequency channel setting means 25 for setting a channel and selecting optical signals from the plurality of branch branches, and an output terminal 26 for outputting the outputs of the plurality of optical frequency channel setting means 25 to an optical transmission line, respectively.
It is characterized by having and.

The operation of the switching device having such a configuration will be described.

FIG. 2 is a block diagram of a second embodiment of the present invention, which is an active spare switching device. 2, the optical delay difference compensating means 27, 28 ₁ to 28 ₅ are optical branching unit, an optical delay difference detection control means 29, 31 are terminals.

In FIG. 1, input terminals 23 are assigned optical frequencies independent of each other, and are connected to digital optical signal channels which are respectively subjected to optical frequency shift keying (FSK) modulation. The optical signal from the input terminal 23 is guided to the input side of the optical signal combining / splitting means 24, and the optical frequency multiplexed signal (FDM) is generated in this combining portion.
Signal). Further, the optical signal combining / splitting means 2
The output side of 4 is a plurality of branching branches for distributing the combined optical frequency multiplexed signal with substantially equal light intensity, and the optical frequency multiplexed signal is output in parallel to this. .. With respect to this output light, one channel is selected from the optical frequency multiplexed signals in each branch by the optical frequency channel setting means 25 having the following variable frequency characteristics, and the signal light is guided to the output terminal 26. When switching is performed so as to guide an arbitrary channel to an arbitrary output terminal, the filter characteristic of the optical frequency channel setting means 25 is changed to extract an arbitrary optical frequency from the optical frequency multiplexed signal. Channel switching becomes possible. The wavelengths λ1 to λ5 on the output side in FIG. 1 show one example.

In FIG. 2, optical frequencies independent of each other are assigned to the input terminal 23, and digital optical signal channels each subjected to optical frequency shift keying (FSK) modulation are connected thereto. The optical signal from the input terminal 23 is guided to the input side of the optical signal combining / splitting unit 24, where it is combined as an optical frequency multiplexed signal (FDM signal). Further, the output side of the optical signal synthesizing / branching means 24 is a plurality of branching branches for distributing the synthesized optical frequency-multiplexed signal with substantially equal light intensity, and the optical frequency-multiplexed signal is parallel to this. Will be output. This output light is guided to the output terminal via the optical branching means 28 by selecting one channel from the optical frequency multiplexed signals in each branch by the optical frequency channel setting means 25 having the following variable frequency characteristics. Here, when performing switching to lead any channel to any output terminal,
By changing the filter characteristic of the optical frequency channel setting means 25, an arbitrary optical frequency can be extracted from the optical frequency multiplexed signal.

From such a state, as an example, the output terminal 26
A switching procedure for providing the input working channel optical signal given by the optical frequency λ2 of _{2 to} the output terminal 26 ₅ of the standby system without interruption will be described. Now, for the inputs from the input terminals 23 ₁ to 23 ₄ , the output from the output terminal 26 ₁ to the output terminal 26 ₄ operates as the working channel at the optical frequency λ1 to the optical frequency λ4, and the output terminal 26 ₅ is the backup system output terminal. It is supposed to be prepared as. Upon switching, the optical frequency channel setting means 25 ₅ is first set to the optical frequency λ2 at which the optical frequency extraction characteristic is to be switched, and the optical branching means 28 is arranged so as to branch the output optical signal of the optical delay difference compensating means 27 ₅ into two. Lead to ₅ . At this time, one output light of the optical branching means is guided to the output terminal 26 side by the optical branching means 28 ₂ and 28 ₅ , and at the same time, the other optical output is also guided to the optical delay difference detection control means 29.

Therefore, the optical delay difference detection control means 29 has the same optical frequency λ2 from both the active system and the standby system.
The signal light of is ready to be detected. Optical delay difference compensating means 2
In FIG. 7, after receiving the optical signals of both systems and converting them into a bit sequence of a digital signal, it is measured how many bits of the signals of both systems are relatively delayed, and the optical delay difference compensating means 27.
Adjust ₅ to compensate for the relative time delay of both systems. In this way, after detecting that neither signal loss nor duplication occurs between the optical signals of the two systems, the switching timing signal is output to the terminal 31 and the devices connected to the output terminals 26 ₂ and 26 ₅ are connected. It is possible to set a state in which switching can be performed without interruption. That is, the subsequent devices connected to the output terminals 26 ₂ and 26 ₅ can receive the switching timing signal from the terminal 31 and synchronously change the optical signal path to shift to the next processing operation. Here, it is possible to set a state in which the hitless switching is completed.

FIG. 3 is a block diagram showing the configuration of an active backup switching device according to the third embodiment of the present invention.

In FIG. 3, reference numeral 30 is an optical separating / connecting means and 32 is a switching control signal. Optical frequencies independent of each other are assigned to the input terminal 23, and digital optical signal channels which are subjected to optical frequency shift keying (FSK) modulation are connected to the input terminals 23, respectively. The optical signal from the input terminal 23 is guided to the input side of the optical signal combining / splitting unit 24, where it is combined as an optical frequency multiplexed signal (FDM signal). Further, the optical signal combining / splitting means 2
The output side of 4 is a plurality of branching branches for distributing the combined optical frequency multiplexed signal with substantially equal light intensity, and the optical frequency multiplexed signal is output in parallel to this. .. This output light selects one channel from the optical frequency multiplexed signals in each branch in the optical frequency channel setting means 25 having the following variable frequency characteristics, and is guided to the output terminal 26 via the optical branching means 28. .. Here, when switching is performed so as to lead an arbitrary channel to an arbitrary output terminal, it is possible to change the filter characteristic of the optical frequency channel setting means 25 and extract an arbitrary optical frequency from the optical frequency multiplexed signal. is there. Further, each channel is connected between the optical branching means 28 and the output terminal 26 by an optical separating / connecting means 30, and each optical separating / connecting means 3 is connected.
0 ₁ to 30 ₅ can be separated and connected at any timing.

From such a state, as an example, the output terminal 26
A switching procedure for providing the input working channel optical signal given by the optical frequency λ2 of _{2 to} the output terminal 26 ₅ of the standby system without interruption will be described. Now, from the input terminal 23 ₁ to the input terminal 23 ₄
Output terminal 26 ₁ to output terminal 26 ₄
Output from the optical frequency λ1 to the optical frequency λ4 and operates as a working channel, and the output terminal 26 ₅ is prepared as a standby system output. In addition, the optical separation / connection means 30 ₁ to 30 ₄ of the working system are in the connected state, while the optical separation / connection means 30 ₅ of the standby system is in the separated state. Upon switching, the optical frequency channel setting means 25 ₅ is first set to the optical frequency λ2 at which the optical frequency extraction characteristic is to be switched, and the optical branching means 2 is set so that the output optical signal of the optical delay difference compensating means 27 ₅ is branched into two.
Lead to 8 ₅ . At this time, one output light of the optical branching means is guided to the output terminal 26 side by the optical branching means 28 ₂ and 28 ₅ , and at the same time, the other optical output is also guided to the optical delay difference detection control means 29.

Therefore, the optical delay difference detection control means 29 has the same optical frequency λ2 from both the active system and the standby system.
The signal light of is ready to be detected. Optical delay difference compensating means 2
In FIG. 9, after receiving the optical signals of both systems and converting them into a bit sequence of a digital signal, it is measured which bit of the signals of both systems is relatively delayed, and the optical delay difference compensating means 27.
Adjust ₅ to compensate for the relative time delay of both systems. In this way, after detecting that neither signal loss nor duplication occurs between the optical signals of the two systems, a switching command is output by the switching control signal 32 to bring the optical demultiplexing connection means 30 ₅ into the connected state. This makes it possible to set a state in which switching can be performed without interruption. That is, the output terminal 26 _{2-26 5,}
Upon receiving the switching control signal 32, the non-instantaneous switching between the output terminals 26 ₂ and 26 ₅ is completed.

FIG. 4 is a block diagram of the optical signal combining / splitting means of the active spare switching device of the present invention. FIG. 5 is a block diagram of the optical frequency setting means of the active spare switching device of the present invention. FIG. 6 is a block diagram of the optical connection / separation means of the active spare switching device of the present invention. FIG. 7 is a block diagram of the optical delay difference compensating means of the active standby switching device of the present invention.

The optical signal combining / splitting means in the present invention is shown in FIG.
It can be realized by using an optical star coupler having an N × N configuration as shown in FIG. This is composed of a dielectric optical waveguide, and N pieces of input light from the optical input terminal indicated by N _i are combined into two systems by a waveguide having a branch structure, and N pieces of input light are provided by repeating this. Input lights having different optical frequencies are combined into one optical frequency multiplexed signal. On the other hand, the output light output at approximately the same light intensity optical frequency multiplexed signal into N optical output terminal N _o by providing a waveguide structure of a completely reverse the synthesis method of the optical signal in the input light. The photosynthesis branching means in the present invention can be realized as long as the relationship between the input and output of light realizes a function such as N input and N output. The optical branching means can be realized by using a structure such as the optical star coupler described above and having one terminal on the input side and two terminals on the output side. The optical branching means in the present invention can be realized as long as it realizes a function of branching one input into two. The optical frequency channel setting means is realized by selecting one channel from the optical multiplexed signal by using a frequency selection filter with a periodic type branching device as shown in FIG. 5 (a). FIG. 5A shows the principle of construction of the waveguide periodic filter. This is a Mach-Zehnder type optical frequency selection filter and is composed of a dielectric optical waveguide. The two optical waveguide arms L1 and L2 having different propagation distances are connected by a directional coupler. In such a configuration, for example, the frequency-multiplexed input light having the frequencies f1 and f2 from the optical input terminal 40 has a difference Δf between the optical frequencies f1 and f2 due to the difference Δ1 in the propagation delay of the light in the arms L1 and L2. Δf =
Under the condition that f2-f1 = c / 2nΔ1 is satisfied, an opposite phase signal is superimposed on one frequency f2, and the other frequency is taken out to the optical output terminal 39 by canceling the signal. It is possible. Where c
Is the velocity of light in a vacuum and n is the refractive index of the optical waveguide. In the structure as shown in FIG. 5A, the propagation distance of light is realized by thermally changing the refractive index n of the waveguide by the electrode 33 provided on the arm L1.

Further, by connecting such filters in multiple stages, it is possible to extract any one frequency from a large number of optical frequency multiplexed signals.
FIG. 5B is a schematic diagram showing the configuration of the multi-stage periodic demultiplexer. For example, when there are four frequencies f1, f2, f3 and f4, the frequencies f1, f3 and f
2, the frequency f4 is demultiplexed, and then the final four frequencies are demultiplexed as independent signals by the second-stage demultiplexer 43. The optical frequency setting means of the present invention can be realized as long as it can demultiplex any one frequency from the frequency-multiplexed optical signal.

The optical connection / separation means is realized by an optical switch as shown in FIG. This is a Mach-Zehnder type optical switch composed of a dielectric optical waveguide. Input light from the optical input terminal 44 is branched into the optical waveguides 45A and 45B. The branched lights are combined again, and the output light is output to the light output terminal 46. Here, electrodes are arranged on the optical waveguides 45A and 45B, respectively, and the electrode 47B is grounded to have the potential "0". On the other hand, an appropriate DC voltage is applied to the electrode 47A. By adjusting this voltage, when the signals from both waveguides are combined, when the voltage of the electrode 47A is adjusted so that the signals of the two waveguides are superimposed in the opposite phase, they are separated (off) and in the same phase. It is placed in the connected (on) state when the voltage is adjusted so that it is polymerized. The optical connection / separation means in the present invention can be realized as long as it has a function of connecting / separating optical signals.

The optical delay difference compensating means is realized by an optical delay compensating circuit as shown in FIG. 2 × optical delay compensation circuit
2 delay compensation optical switch 48, optical line 49 with optical delay time “0”, optical delay line 50 for setting unit optical delay, and optical delay lines 50, 51, 52 having an optical delay amount that is an integral multiple thereof and minute delay It is composed of an optical delay compensation line 56 wound around a piezoelectric element 55 for setting time. The optical delay lines 51 and 52 in FIG. 7 are twice and three times as many as the optical delay lines that set the unit optical delay, respectively. Now, assuming that the delay compensation time of the optical delay line 50 is ΔT, the optical delay line 51 is 2T and the optical delay line 52 is
Can set a delay compensation time of 3T. The optical input from the input terminal 53 is compensated for an integral multiple of the unit optical delay compensation amount according to the setting method of the delay compensation optical switch 48, and is output to the output terminal 58. The embodiment of FIG. 7 is a case where 2T delay compensation is realized. In such a multi-stage delay compensating circuit, the delay increase / decrease is performed digitally, so that the delay compensation from "0" to "T" is not performed. Therefore, in order to compensate for the delay from "0" to "T", the optical delay compensation line 56 is wound around the piezoelectric element 55, a voltage is applied from the electrode 57 to the piezoelectric element 55, and the optical delay compensation line 56 is applied. The optical path length is finely adjusted by applying tension to the optical delay compensating line 56 wound around the optical path and the final optical delay-compensated optical signal is obtained at the output terminal 58. The optical delay compensating means in the present invention can be realized by any optical circuit capable of controlling an arbitrary optical delay.

[0035]

As described above, according to the present invention, the hardware scale is minimized without converting an optical signal into an electric signal, and the working standby is performed without interruption without impairing the original high speed of light. There is an excellent effect that can be switched.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an active backup switching device according to a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of an active backup switching device according to a second embodiment of the present invention.

FIG. 3 is a block configuration diagram of an active backup switching device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of an optical signal combining / branching unit of the active backup switching device of the present invention.

FIG. 5 is a configuration diagram of an optical frequency setting unit of the active backup switching device of the present invention.

FIG. 6 is a configuration diagram of an optical separating / connecting unit of the active backup switching device of the present invention.

FIG. 7 is a configuration diagram of an optical delay difference compensating means of the active backup switching device of the present invention.

FIG. 8 is a block configuration diagram of a digital optical transmission device in which a conventional active switching device is used.

FIG. 9 is a block configuration diagram of a cross-connect device on the transmission side of a digital optical transmission device in which a conventional standby switching device is used.

FIG. 10 is a block configuration diagram of a cross-connect device on the reception side of a digital optical transmission device in which a conventional standby switching device is used.

FIG. 11 is a block configuration diagram of a transmission path changeover switch of a digital optical transmission device in which a conventional standby switching device is used.

FIG. 12 is an explanatory diagram of a frequency multiplexing method of an optical frequency multiplexing transmission system.

[Explanation of symbols]

1A Transmitting side transmission device 1B Receiving side transmission device 2A, 2B Cross-connect device 3A High-speed multiplexer / conversion device 3B High-speed demultiplexing device 4A, 4B Transmission line changeover switch 5, 6 Interface circuit 7 Working optical transmission line 8 Standby optical transmission line 9A Multiplexing device 9B Demultiplexing device 10A to 10C, 14A to 14C Digital time division multiplexing optical signal sequence 10D to 10F Time slot 11 Input interface 12, 16 Cross-connect demultiplexing conversion circuit 13, 15 Cross-connect circuit 17 Output interface 19A, 19B Delay compensation circuit 20 Delay difference compensation detection circuit 20A, 20B, 21, 21A, 21B, 22, 22A
, 22B, 31,54 terminals 23 ₁ to 23 _5, 53 input terminal 24 the optical signal combining branching means 25 and 25 _to 253 ₅ optical frequency channel setting unit 26 ₁ to 26 _5, 58 Output terminals 27 and 27 _{1 to} 27 ₅ Optical delay difference compensating means 28 _{1 to} 28 ₅ Optical branching means 29 Optical delay difference detection control means 30, 30 ₁ to 30 ₅ Optical separating / connecting means 32 Switching control signal 33, 47A, 47B, 57 Electrode 39 Optical output Terminal 42, 43 Demultiplexer 40, 44 Optical input terminal 45A, 45B Optical waveguide 41, 46 Optical output terminal 48 Delay compensation optical switch 49 Optical line 50 to 52 Optical delay line 55 Piezoelectric element 56 Optical delay compensation line 60 Electro-optical conversion Circuit 61 Photoelectric conversion circuit λ1 to λ5 Optical frequency

Claims (3)

[Claims] 1. In an active standby switching device in which an optical transmission line is redundantly configured and a part of the optical transmission line is in a standby state for standby, an optical frequency digital signal of a plurality of channels to be input is converted into an optical frequency multiplexed signal. Optical signal synthesizing / branching means for synthesizing and distributing the optical frequency multiplexed signal to a plurality of branch branches, and optical signals from the plurality of branch branches by setting predetermined optical frequency channels for the plurality of branch branches. And a plurality of optical frequency channel setting means for selecting, and an output terminal for outputting the outputs of the plurality of optical frequency channel setting means to an optical transmission line, respectively. 2. The output of the optical frequency channel setting means based on a delay difference compensation control signal inserted and inputted between at least two optical frequency channel setting means for setting the optical frequency channel to be switched and the corresponding output terminals. An optical delay difference compensating means for compensating for the delay difference, an optical branching means inserted between the optical delay difference compensating means and the corresponding output terminal for branching the output of the optical delay difference compensating means, and the optical branching means. The optical delay difference detection control for detecting the bit phase difference of the optical signal series output by the optical delay difference compensating means based on the output of the above, outputting the delay difference compensation control signal, and outputting the switching control signal when the bit phases match. And means.
The currently used standby switching device. 3. An optical separating / connecting means which is inserted between the optical branching means and an output terminal corresponding to the optical branching means, and which connects and disconnects the optical branching means and the corresponding output terminal based on the switching control signal. The switching device according to claim 2.