JP3293738B2 - Phase-locked system and constituent devices of the phase-locked system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase synchronization system for realizing phase synchronization between a main unit and a slave unit connected via an optical transmission line in a wavelength division multiplexing bidirectional communication system, and the phase synchronization system. Related to a constituent device.

[0002]

2. Description of the Related Art As a conventional method for realizing phase synchronization between a master device and a slave device that are opposed via an optical transmission line, an optical signal is transmitted from the master device to a slave device using a folded optical transmission line. There has been a method in which a delay time when a device makes a round trip to a device is measured, a half of the delay time is determined as a one-way delay time, and the phase is corrected based on the one-way delay time.

FIG. 10 is a block diagram showing a configuration example of a conventional phase synchronization system. In the figure, a master transmission unit 110 and a slave reception unit 120 which are opposed to each other are connected via two optical transmission lines 101 and 102. The reference phase signal a generated by the reference transmitter 111 of the main device transmission unit 110 is input to the slave device reception unit 120 via the outward optical transmission line 101. At this time, the reference phase signal a is
The phase changes due to the transmission delay, and becomes a phase signal b.
The phase signal b transmitted to the slave device receiving unit 120 is input to the phase adjusting unit 121, and is transmitted to the optical transmission line 10 on the return path.
2 is returned to the main device transmission unit 110. At this time, the phase of the phase signal b changes due to a delay in transmission,
It becomes the phase signal c. The phase signal c returned to the main device transmission unit 110 is input to the phase comparison unit 112.

[0004] The phase comparator 112 measures a phase difference ΔD between the reference phase signal a and the phase signal c. At this time, assuming that the delay time in the outward optical transmission line 101 is T1 and the delay time in the return optical transmission line 102 is T2, the phase difference ΔD
Is ΔD = T1 + T2 (1). Therefore, the one-way delay time ΔT measured by the phase comparison unit 112 is ΔT = ΔD / 2 = T1 + (T2−T1) / 2 (2)

Here, the optical transmission line 101 on the outward path and the optical transmission line 102 on the return path are generally housed in physically independent optical fiber cores, but usually the same optical fiber cable (a plurality of fibers are bundled). Stuff). Therefore, both lengths are almost equal, T1 ≒ T2, and (T2−T1) / 2 ≒ 0. Therefore, the delay time ΔT is regarded as the outward delay time T1, and this is transmitted to the slave device receiver 120 as the delay information e. The phase adjusting unit 121 of the slave device receiving unit 120 includes:
The phase of the phase signal b is controlled based on the delay information e,
A phase signal d synchronized with the reference phase signal a is generated. Accordingly, phase synchronization can be realized between master device transmitting section 110 and slave apparatus receiving section 120.

As a method for realizing bidirectional communication using one optical fiber, there is a bidirectional communication system using two lights having different wavelengths. FIG. 11 is a block diagram illustrating a configuration example of a wavelength division multiplexing bidirectional communication system. In this figure, two opposing communication devices 210,
220 is connected via one optical transmission line 201. The optical transmitter 211 of the communication device 210
It communicates with the 0 optical receiver 221 using an optical signal of wavelength λ1. Further, the optical transmitter 222 of the communication device 220 transmits the wavelength λ2 (≠ λ) to the optical receiver 212 of the communication device 210.
Communicate with the optical signal of 1). The optical signals of the wavelengths λ1 and λ2 are combined and separated by the wavelength multiplexers / demultiplexers 213 and 223. FIG.
In the system shown in (1), two-way simultaneous communication is possible using one optical transmission line 201, so that efficient communication can be realized.

[0007]

By the way, in the conventional phase locked loop system shown in FIG. 10, from the equation (2), the delay time T1 in the forward optical transmission line 101 and the delay time T2 in the backward optical transmission line 102 are obtained.の, ie, (T2−T1) / 2, is the error. In optical fiber communication in the current telephone network, an optical fiber cable in which several to several hundred optical fiber cores are accommodated in one cable is used. Therefore, there is a high possibility that the optical fiber cable in the forward path and the optical fiber cable in the return path are accommodated in the same optical fiber cable. However, even if the optical fiber cable in the forward path and the optical fiber cable in the return path are accommodated in the same optical fiber cable, the connection of the connector at the terminal section of the optical fiber cable, the transmission section and the reception section in the terminal apparatus, and the like. The optical fiber lengths of the forward path and the return path may be different due to the difference in the position of the optical fiber. Further, in long-distance communication via a number of devices such as relay devices, the difference between the forward path and the return path is further increased. For example, in a transmission path of about 2000 km, the difference between the delay time of the forward path and the delay time of the return path is larger. It is about 100 ns. This delay time difference is an amount that cannot be ignored when performing ultra-high-precision phase synchronization, and has been a problem of the conventional phase synchronization system shown in FIG.

In the wavelength division multiplexing bidirectional communication system shown in FIG. 11, the propagation time of an optical signal in an optical fiber varies depending on the wavelength due to the chromatic dispersion of the optical fiber. For example, a dispersion-shifted fiber adjusted so that the chromatic dispersion becomes almost zero when the wavelength is 1.55 μm is 1.54 μm.
In the wavelength band of μm to 1.56 μm, 2.5 ps / nm
km of wavelength dispersion is allowed. With respect to such chromatic dispersion, for example, when optical transmission of 1000 km is performed using two optical signals having wavelengths separated by 10 nm from each other, a maximum of
A delay time difference of 25 ns will occur. This delay time difference is an amount that cannot be ignored when performing ultra-high-precision phase synchronization, and it is not possible to simply combine a wavelength division multiplexing bidirectional communication system with a conventional phase synchronization system.

The present invention provides a phase synchronization system for realizing highly accurate phase synchronization between a master device and a slave device without being affected by chromatic dispersion in an optical transmission line in a wavelength division multiplexing bidirectional communication system. The purpose is to do.

[0010]

SUMMARY OF THE INVENTION A phase synchronization system according to the present invention measures a phase difference between respective wavelengths by wavelength division multiplexing bidirectional communication for transmitting an optical signal of two wavelengths in two directions, and an optical signal of two wavelengths. The measurement is performed by switching the phase difference measurement between each wavelength by wavelength division multiplexing communication that transmits in the same direction, comparing the respective phase difference information, and determining the delay time between the master device and the slave device. is there.

According to a first aspect of the present invention, an optical signal is received from an optical fiber to which a transmission device provided in a master device or a slave device is connected, and an optical signal having a wavelength λ1 and an optical signal having a wavelength λ2 are received from the received optical signal. Optical multiplexer / demultiplexer for separating an optical signal (21)
A first optical receiver (22) for separating a first phase signal (c) from the optical signal of wavelength λ1 separated by the optical multiplexer / demultiplexer (21), and the optical multiplexer / demultiplexer (21) Separated wavelength λ
A second optical receiver (24) for separating a second phase signal (d) from the second optical signal; and a phase difference between the first phase signal (c) and the second phase signal (d). That is, a first delay time (T1) for the optical signal of the wavelength λ1 to reach the present device from the transmitting device and a second delay time for the optical signal of the wavelength λ2 to reach the present device from the transmitting device. A phase comparator (26) for calculating a difference (T1−T2) from the delay time (T2) and outputting second phase difference information (g) representing the phase difference.
And an optical signal having a wavelength λ2 modulated by the first phase signal (c) is generated, and the optical signal is combined with the optical multiplexer / demultiplexer (21).
An optical transmitter (27) for transmitting the optical fiber to the optical fiber via the optical fiber
A state in which the optical multiplexer / demultiplexer (21) inputs the separated optical signal of the wavelength λ2 to the second optical receiver (24) (state 2), and a wavelength generated by the optical transmitter (27). an optical switch (23) for switching a state (state 1) of inputting an optical signal of λ2 to the optical multiplexer / demultiplexer (21), a switching control signal (e) for switching a state of the optical switch (23),
And an information transfer unit (29) for externally receiving first phase difference information (f) representing the sum (T1 + T2) of the first delay time (T1) and the second delay time (T2). When,
A switching control signal (e) received by the information transfer unit (29).
A controller (28) that controls the state of the optical switch (23) based on the value (T1 + T2) represented by the first phase difference information (f) and the second phase difference information (g). A delay time calculating section (25) for calculating the first delay time (T1) by dividing the sum of the value and the value (T1-T2) by 2;
The delay time (T1) obtained by the delay time calculator (25)
The phase adjustment unit (25) that generates a phase signal (a ′) synchronized with the reference phase signal (a) generated by the transmitting device by adjusting the phase of the first phase signal (c) based on ).

According to a second aspect of the present invention, there is provided a reference oscillator (11) for generating a reference phase signal (a), and a light having a wavelength λ1 modulated by the reference phase signal (a) generated by the reference oscillator (11). First optical transmitter for generating a signal (12)
A second optical transmitter (13) for generating an optical signal of wavelength λ2 modulated by the reference phase signal (a) generated by the reference oscillator (11); and the first optical transmitter (12) And the second optical transmitter (13).
And multiplexes the generated optical signal of wavelength λ2, sends the multiplexed optical signal to an optical fiber to which a receiving device provided in a slave device is connected, and receives an optical signal from the optical fiber. An optical multiplexer / demultiplexer (15) for separating the optical signal of the wavelength λ2 from the received optical signal, and the optical multiplexer / demultiplexer (15)
And a phase difference between the reference phase signal (a) and the phase signal (b), ie, the wavelength difference between the optical signal (b) and the reference phase signal (a).
A first delay time (T1) for the optical signal of the present device to reach the receiving device from the present device and a second delay time (T) for the optical signal of the wavelength λ2 to reach the present device from the receiving device.
2) and a phase comparator (14) for outputting first phase difference information (f) representing the phase difference, and a wavelength generated by the second optical transmitter (13). A state in which an optical signal of λ2 is input to the optical multiplexer / demultiplexer (15) (state 2)
An optical switch (16) that switches between a state (state 1) in which the optical multiplexer / demultiplexer (15) separates the optical signal of wavelength λ2 into the optical receiver (17); and the optical switch (16). And a switching control signal (e) output by the control unit (18), and a switching control signal (e) representing the control state.
An information transfer unit (19) for transmitting the first phase difference information (f) output from the phase comparison unit (14) to the outside is provided.

According to a third aspect of the present invention, there is provided a first optical transmitter (12) for generating an optical signal of wavelength λ1 modulated by an externally input reference phase signal (a); a second optical transmitter (13) for generating an optical signal of wavelength λ2 modulated in a), an optical signal of wavelength λ1 generated by the first optical transmitter (12), and the second optical transmission Tableware (13)
And multiplexes the generated optical signal of wavelength λ2, sends the multiplexed optical signal to an optical fiber to which a receiving device provided in a slave device is connected, and receives an optical signal from the optical fiber. An optical multiplexer / demultiplexer (15) for separating the optical signal of the wavelength λ2 from the received optical signal, and the optical multiplexer / demultiplexer (15)
And a phase difference between the reference phase signal (a) and the phase signal (b), ie, the wavelength difference between the optical signal (b) and the reference phase signal (a).
A first delay time (T1) for the optical signal of the present device to reach the receiving device from the present device and a second delay time (T) for the optical signal of the wavelength λ2 to reach the present device from the receiving device.
2) and a phase comparator (14) for outputting first phase difference information (f) representing the phase difference, and a wavelength generated by the second optical transmitter (13). A state in which an optical signal of λ2 is input to the optical multiplexer / demultiplexer (15) (state 2)
An optical switch (16) that switches between a state (state 1) in which the optical multiplexer / demultiplexer (15) separates the optical signal of wavelength λ2 into the optical receiver (17); and the optical switch (16). And a switching control signal (e) output by the control unit (18), and a switching control signal (e) representing the control state.
An information transfer unit (19) for transmitting the first phase difference information (f) output from the phase comparison unit (14) to the outside is provided.

According to a fourth aspect of the present invention, an optical signal is received from an optical fiber to which a transmitting device provided in a master device or a slave device is connected, and an optical signal having a wavelength λ1 and an optical signal having a wavelength λ2 are received from the received optical signal. Optical multiplexer / demultiplexer for separating an optical signal (21)
A first phase signal (c), a switching control signal (e), and first phase difference information (f) for separating the first phase signal (c), the switching control signal (e), and the first phase difference information (f) from the optical signal of wavelength λ1 separated by the optical multiplexer / demultiplexer (21). Optical receiver (2
2 ′) and the wavelength λ2 separated by the optical multiplexer / demultiplexer (21).
A second optical receiver (24) for separating a second phase signal (d) from the optical signal of the second phase, a phase difference between the first phase signal (c) and the second phase signal (d), That is, the wavelength λ
A first delay time (T1) for one optical signal to reach the present device from the transmitting device and a second delay time (T1) for the optical signal of the wavelength λ2 to reach the present device from the transmitting device.
2), and a phase comparison unit (26) for outputting second phase difference information (g) representing the phase difference, and a signal modulated by the first phase signal (c). An optical transmitter (27) for generating an optical signal having the wavelength λ2 and transmitting the optical signal to the optical fiber via the optical multiplexer / demultiplexer (21), and the optical multiplexer / demultiplexer (21) A state where the separated optical signal of wavelength λ2 is input to the second optical receiver (24) (state 2)
An optical switch (23) for switching between a state (state 1) of inputting an optical signal of wavelength λ2 generated by the optical transmitter (27) to the optical multiplexer / demultiplexer (21), and the first optical receiver A controller (28) for controlling the state of the optical switch (23) based on the switching control signal (e) separated by the device (22 '), and a value represented by the first phase difference information (f) ( T
1 + T2) and the value (T1) represented by the second phase difference information (g).
-T2) is divided by 2 to provide a delay time calculator (25) for calculating the first delay time (T1) and a delay time (T1) calculated by the delay time calculator (25). Adjusting the phase of the first phase signal (c) based on the reference phase signal (a) generated by the transmitting device.
Phase adjuster (2) that generates a phase signal (a ′) synchronized with
5).

According to a fifth aspect of the present invention, there is provided a reference oscillator (11) for generating a reference phase signal (a), and a light having a wavelength λ1 modulated by the reference phase signal (a) generated by the reference oscillator (11). First optical transmitter for generating a signal (12 ')
A second optical transmitter (13) for generating an optical signal of wavelength λ2 modulated by the reference phase signal (a) generated by the reference oscillator (11); and the first optical transmitter (12 ') ) Generated by the optical signal of wavelength λ1 and the second optical transmitter (1).
3) multiplexes the generated optical signal with the wavelength λ2, sends the multiplexed optical signal to the optical fiber connected to the receiving device provided in the slave device, and converts the optical signal from the optical fiber. An optical multiplexer / demultiplexer (15) for receiving and separating the optical signal of the wavelength λ2 from the received optical signal;
5) an optical receiver (17) for separating the phase signal (b) from the separated optical signal of wavelength λ2, and the reference phase signal (a).
And the phase signal (b), that is, the first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving device from the present device and the optical signal of the wavelength λ2 are A phase comparator (14) for obtaining a sum (T1 + T2) with a second delay time (T2) from the device to the present device and outputting first phase difference information (f) representing the phase difference;
And a state (state 2) in which the optical signal of wavelength λ2 generated by the second optical transmitter (13) is input to the optical multiplexer / demultiplexer (15), and the optical multiplexer / demultiplexer (15) is separated. An optical switch (16) for switching between a state (state 1) for inputting an optical signal of wavelength λ2 to the optical receiver (17), and a switch for controlling the state of the optical switch (16) and indicating the control state A control unit (18) for outputting a control signal (e), a switching control signal (e) output from the control unit (18), and first phase difference information ( f) superimposing means (12 ') for superimposing f) on the optical signal of wavelength λ1 generated by the first optical transmitter (12').

According to a sixth aspect of the present invention, there is provided a first optical transmitter (12 ') for generating an optical signal having a wavelength λ1 modulated by an externally input reference phase signal (a), and the reference phase signal A second method for generating an optical signal of wavelength λ2 modulated in (a)
Optical transmitter (13), and the first optical transmitter (12 ′)
Generates the optical signal of wavelength λ1 and the second optical transmitter (1).
3) multiplexes the generated optical signal with the wavelength λ2, sends the multiplexed optical signal to the optical fiber connected to the receiving device provided in the slave device, and converts the optical signal from the optical fiber. An optical multiplexer / demultiplexer (15) for receiving and separating the optical signal of the wavelength λ2 from the received optical signal;
5) an optical receiver (17) for separating the phase signal (b) from the separated optical signal of wavelength λ2, and the reference phase signal (a).
And the phase signal (b), that is, the first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving device from the present device and the optical signal of the wavelength λ2 are A phase comparator (14) for obtaining a sum (T1 + T2) with a second delay time (T2) from the device to the present device and outputting first phase difference information (f) representing the phase difference;
And a state (state 2) in which the optical signal of wavelength λ2 generated by the second optical transmitter (13) is input to the optical multiplexer / demultiplexer (15), and the optical multiplexer / demultiplexer (15) is separated. An optical switch (16) for switching between a state (state 1) for inputting an optical signal of wavelength λ2 to the optical receiver (17), and a switch for controlling the state of the optical switch (16) and indicating the control state A control unit (18) for outputting a control signal (e), a switching control signal (e) output from the control unit (18), and first phase difference information ( f) superimposing means (12 ') for superimposing f) on the optical signal of wavelength λ1 generated by the first optical transmitter (12').

According to a seventh aspect of the present invention, the first light according to the third aspect uses the phase signal (a ') generated by the phase adjusting section (25) according to the first aspect as a reference phase signal (a). The transmitter (12), the second optical transmitter (13), and the phase comparator (1)
4), the receiving device according to claim 1 and the transmitting device according to claim 3 are combined into one transmitting / receiving device.

According to an eighth aspect of the present invention, the first light according to the sixth aspect uses the phase signal (a ') generated by the phase adjusting section (25) according to the fourth aspect as a reference phase signal (a). The transmitter (12 '), the second optical transmitter (13), and the phase comparator (1
4), the receiving device according to claim 4 and the transmitting device according to claim 6 are combined into one transmitting / receiving device.

A ninth aspect of the present invention is characterized in that the transmitting apparatus according to the second aspect and the receiving apparatus according to the first aspect are connected by an optical fiber.

According to a tenth aspect of the present invention, the transmitting device according to the fifth aspect and the receiving device according to the fourth aspect are connected by an optical fiber.

According to an eleventh aspect of the present invention, the transmitting device according to the second aspect, at least one transmitting / receiving device according to the seventh aspect, and the receiving device according to the first aspect are connected in tandem by an optical fiber. And

According to a twelfth aspect of the present invention, the transmitting device according to the fifth aspect, at least one transmitting / receiving device according to the eighth aspect, and the receiving device according to the fourth aspect are connected in tandem by optical fibers. And

According to a thirteenth aspect of the present invention, there is provided a phase synchronization system in which a repeater having the following features is arranged between the respective devices according to the ninth or eleventh aspects.
The repeater receives an optical signal from an optical fiber to which a transmitting device provided in a master device or a slave device is connected, and separates an optical signal of wavelength λ1 and an optical signal of wavelength λ2 from the received optical signal. A first optical multiplexer / demultiplexer (31-1); and a first optical repeater (32-1) for relaying an optical signal of wavelength λ1 separated by the first optical multiplexer / demultiplexer (31-1). A second optical repeater (32-2) for relaying an optical signal of wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1), and the first optical repeater (32-1) And the second optical signal of wavelength λ1
Multiplexes the optical signal of wavelength λ2 relayed by the optical repeater (32-2), and converts the multiplexed optical signal to an optical signal connected to a receiving device provided in a slave device different from the slave device. A second optical multiplexer / demultiplexer (31-2) for transmitting an optical signal from the optical fiber and separating the optical signal of the wavelength λ2 from the received optical signal; A third optical repeater (32-3) for relaying the optical signal of wavelength λ2 separated by the splitter (31-2); and a wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1). Is input to the second optical repeater (32-2), and the optical signal of wavelength λ2 relayed by the second optical repeater (32-2) is input to the second optical repeater (32-2).
Input to the optical multiplexer / demultiplexer (31-2) (state 2)
And the second optical multiplexer / demultiplexer (31-2) inputs the optical signal of the wavelength λ2 separated by the second optical multiplexer / demultiplexer (31-2) to the third optical repeater (32-3). An optical switch (3) for switching between a state (state 1) in which the optical signal of wavelength λ2 relayed by 32-3) is input to the first optical multiplexer / demultiplexer (31-1).
3-1, 33-2), the switching control signal (e) and the first phase difference information (f) from the transmitting device, and the switching control signal (e) and the first phase difference An information transfer unit (35) for transmitting information (f) to the receiving device;
And the optical switch (33-1, 33-) based on the switching control signal (e) received by the information transfer section (35).
A control unit (34) for controlling the state of 2).

According to a fourteenth aspect of the present invention, there is provided a phase synchronization system in which a repeater having the following characteristics is provided between the respective devices according to the tenth or twelfth aspects. The repeater receives an optical signal from an optical fiber to which a transmitting device provided in a master device or a slave device is connected, and separates an optical signal of wavelength λ1 and an optical signal of wavelength λ2 from the received optical signal. A first optical multiplexer / demultiplexer (31-1);
The optical multiplexer / demultiplexer (31-1) relays the separated optical signal of the wavelength λ1 and separates the switching control signal (e) from the optical signal of the wavelength λ1. )When,
The wavelength .lambda.2 separated by the first optical multiplexer / demultiplexer (31-1).
A second optical repeater (32-2) for relaying the optical signal of the second optical repeater (32-2), and an optical signal of wavelength λ1 relayed by the first optical repeater (32-1 ') and the second optical repeater (32-2). -2) multiplexes the relayed optical signal of wavelength λ2 and sends the multiplexed optical signal to an optical fiber to which a receiving device provided in a slave device different from the slave device is connected, A second optical multiplexer / demultiplexer (31-2) for receiving an optical signal from the optical fiber and separating the optical signal of the wavelength λ2 from the received optical signal; and a second optical multiplexer / demultiplexer (31-). 2) a third optical repeater (32-3) for relaying an optical signal of wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1); 2 to the optical repeater (32-2), and
A state (state 2) in which the optical signal of wavelength λ2 relayed by the second optical repeater (32-2) is input to the second optical multiplexer / demultiplexer (31-2); The optical signal having the wavelength λ2 separated by the optical repeater (31-2) is transmitted to the third optical repeater (32).
-3) and the third optical repeater (32-3)
Optical switches (33-1, 33-2) for switching between a state (state 1) of inputting the optical signal of wavelength λ2 relayed by the first optical multiplexer / demultiplexer (31-1); A control unit (34) for controlling the state of the optical switches (33-1, 33-2) based on the switching control signal (e) separated by the optical repeater (32-1 '). Features.

According to a fifteenth aspect of the present invention, there is provided a phase synchronization system in which a repeater having the following features is placed between the respective devices according to the tenth or twelfth aspects. The repeater receives an optical signal from an optical fiber connected to a transmission device provided in a master device or a slave device, amplifies the received optical signal with pump light, and converts the amplified optical signal into the slave device. A receiving device provided in a slave device different from the device transmits the optical signal to an optical fiber connected thereto, and the receiving device receives an optical signal from the connected optical fiber, and amplifies the received optical signal by pumping light. An optical amplifier (36) for transmitting the amplified optical signal to an optical fiber to which the transmitting device is connected; an excitation light source (37) for emitting the excitation light; and an excitation light source (37). Pump light source input means (38) for inputting pump light to the optical amplification means (36).

[0026]

Embodiments of the present invention will be described below with reference to the drawings. §1. First Embodiment FIG. 1 is a block diagram illustrating a configuration example of a phase synchronization system according to a first embodiment of the present invention. In this figure, a main unit transmitting unit 10 and a slave unit receiving unit 20 are connected via an optical fiber 1.

In the main unit transmitting section 10, the reference oscillator 1
1 outputs a reference phase signal a, and the reference phase signal a
The signals are input to the optical transmitters 12 and 13 and the phase comparison unit 14. The optical transmitter 12 has a wavelength modulated by the reference phase signal a.
An optical signal of 1.31 μm is transmitted to the optical fiber 1 via the optical multiplexer / demultiplexer 15. The optical transmitter 13 sends out an optical signal having a wavelength of 1.55 μm modulated by the reference phase signal a to the optical fiber 1 via the optical switch 16 and the optical multiplexer / demultiplexer 15. An optical signal having a wavelength of 1.55 μm input from the optical fiber 1 is input to the optical receiver 17 via the optical multiplexer / demultiplexer 15 and the optical switch 16. The optical receiver 17 separates the phase signal b from the input optical signal having the wavelength of 1.55 μm, and inputs the phase signal b to the phase comparison unit 14. The control device 18 generates the switching control signal e and
And the switching control signal e is input to the information transfer device 19. The information transfer device 19 converts the switching control device signal e and the phase difference information f output from the phase comparison unit 14 into
It is transmitted to the slave device receiver 20.

In the slave device receiving section 20, the optical fiber 1
The optical signal of wavelength 1.31 μm input from the optical multiplexer / demultiplexer 2
1 is input to the optical receiver 22. An optical signal having a wavelength of 1.55 μm input from the optical fiber 1 is transmitted through an optical multiplexer / demultiplexer 21 and an optical switch 23 to an optical receiver 24.
Is input to The optical receiver 22 separates the phase signal c from the optical signal having the wavelength of 1.31 μm, and supplies the phase signal c to the phase adjuster 25, the phase comparator 26, and the optical transmitter 27.
The optical transmitter 27 has a wavelength of 1.55 μm modulated by the phase signal c.
Is transmitted to the optical fiber 1 via the optical switch 23 and the optical multiplexer / demultiplexer 21. The optical receiver 24 has a wavelength
The phase signal d is separated from the 1.55 μm optical signal, and the phase signal d is supplied to the phase comparator 26. The phase comparison unit 26 calculates phase difference information g indicating the phase difference between the phase signal c and the phase signal d,
It is supplied to the phase adjustment unit 25. The information transfer device 29 receives the switching control signal e and the phase difference information f from the information transfer device 19 of the main device transmitting unit 10, supplies the switching control signal e to the control device 28, and Is supplied to the phase adjustment unit 25. The control device 28 receives the switching control signal e
The optical switch 23 is switched based on.

Here, the optical multiplexers / demultiplexers 15, 21 have wavelengths of 1.
Light having a wavelength of 31 μm and light having a wavelength of 1.55 μm can be multiplexed or separated. For example, as the optical multiplexers / demultiplexers 15, 21, an optical fiber coupler type optical multiplexer / demultiplexer, a Mach-Zehnder interferometer type optical multiplexer / demultiplexer, an optical multiplexer / demultiplexer using a diffraction grating, or the like can be used.

The phase comparison section 14 of the main apparatus transmission section 10 compares the phase difference between the reference phase signal a and the phase signal b, and outputs the obtained phase difference information f via the information transfer apparatuses 19 and 29 to the slave section. The data is transferred to the phase adjustment unit 25 of the device reception unit 20. The phase comparing section 26 of the slave device receiving section 20 comprises a phase signal c and a phase signal d.
And supplies the obtained phase difference information g to the phase adjustment unit 25. As a result, the phase adjuster 25 of the slave device receiver 20 adjusts the phase of the phase signal c based on the phase difference information f and g, and the reference phase signal a of the master device transmitter 10.
And generates a phase signal a 'having the same phase as. The phase adjustment unit 25 can be easily realized by a combination of a programmable counter and a phase locked oscillator.

In the present embodiment, the optical switch 16 of the main unit transmitting unit 10 and the optical switch 23 of the slave unit receiving unit 20 are simultaneously switched, so that the optical transmission path between the master unit transmitting unit 10 and the slave unit receiving unit 20 is changed. 2 (a),
The two states shown in (b) can be formed.

That is, in the state 1 shown in FIG.
After the reference phase signal a is transmitted as an optical signal having a wavelength of 1.31 μm from the main device transmitting unit 10 to the slave device receiving unit 20, the wavelength 1.
The optical signal of 55 μm is returned from the slave device receiver 20 to the master device transmitter 10 to become a phase signal b. Where the wavelength 1.31
from the main unit transmitting unit 10 to the slave unit receiving unit 2 in the light of μm.
Assuming that the delay time due to transmission to 0 is T1 and the delay time due to transmission from the slave unit receiving unit 20 to the main unit transmitting unit 10 for light having a wavelength of 1.55 μm is T2, the phase comparison of the main unit transmitting unit 10 in state 1 is performed. The phase difference measured by the unit 14
1 results in Δ1 = T1 + T2.

In the state 2 in FIG. 2B, the reference phase signal a is simultaneously transmitted from the main unit transmitting unit 10 to the slave unit receiving unit 20 as light having wavelengths of 1.31 μm and 1.55 μm.
Since the transmission delay time due to the optical fiber does not depend on the light transmission direction if the wavelength is the same, the phase difference △ 2 measured by the phase comparator 26 of the slave receiver 20 in state 2
Is Δ2 = T1−T2.

As described above, the optical switches 16 and 23 are switched to measure both the phase difference △ 1 and the phase difference △ 2, and the phase difference Δ1
And the phase difference g indicating the phase difference Δ2,
The delay time T1 can be accurately obtained by taking it into the phase adjusting unit 25 of the slave device receiving unit 20 and performing the operation of T1 = (△ 1 + △ 2) / 2. Phase adjuster 25 of slave device receiver 20
Adjusts the phase of the phase signal c based on the delay time T1 to generate a phase signal a 'having the same phase as the reference phase signal a of the main device transmitter 10.

In the configuration of the present embodiment, the main unit transmitting unit 10
The wavelength error between the light output from the optical transmitter 13 and the light output from the optical transmitter 27 of the slave device receiving unit 20 becomes an error factor of the phase synchronization. However, in an optical transmitter using a semiconductor laser, the selection of the semiconductor laser and control of the temperature and the injection current can be performed without using a special wavelength tuning technique.
Wavelength alignment with an accuracy of 1 nm or less can be easily realized.
Therefore, the phase error due to the wavelength error is sufficiently smaller than the delay time difference between the light having the wavelength of 1.31 μm and the light having the wavelength of 1.55 μm, and thus the configuration of the present embodiment realizes highly accurate phase synchronization.

FIG. 3 is a block diagram showing another configuration example of the phase synchronization system according to the first embodiment of the present invention. The master device transmitting section 10 and the slave device receiving section 20 shown in this figure are the same as those shown in FIG. Further, in this figure, the slave device transmitting / receiving section 40 includes a reference oscillator 11
Is a combination of the main device transmitting unit 10 and the slave device receiving unit 20 except for the above. In the slave transmission / reception unit 40, the phase signal a 'obtained by the phase adjustment unit 45 is input to the optical transmitters 50 and 52 and the phase comparison unit 53 as the reference synchronization signal a. Although the phase synchronization system shown in FIG. 3 has only one slave device transmission / reception unit 40, the same connection is made in multiple stages to construct a phase synchronization system having a plurality of slave device transmission / reception units 40. Can also.

§2. Second Embodiment FIG. 4 is a block diagram illustrating a configuration example of a phase synchronization system according to a second embodiment of the present invention. The feature of this embodiment lies in that the switching control signal e and the phase difference information f described in the first embodiment are superimposed on an optical signal having a wavelength of 1.31 μm and transferred. The optical transmitter 12 ′ of the main device transmitter 10 ′ transmits an optical signal having a wavelength of 1.31 μm modulated by the reference phase signal a to the optical fiber 1 via the optical multiplexer / demultiplexer 15.
The switching control signal e and the phase difference information f are superimposed on the optical signal having a wavelength of 1.31 μm and transmitted to the optical fiber 1.

Correspondingly, the optical receiver 22 'of the slave receiver 20' has a separating function for extracting the switching control signal e and the phase difference information f from the optical signal having the wavelength of 1.31 μm. As a result, the switching control signal e and the phase difference information f are transmitted using the optical fiber 1, so that the information transfer devices 19 and 29 and the transfer path between the information transfer devices shown in the first embodiment are unnecessary. Become.

In this embodiment, the reference phase signal and the phase difference information are transmitted as superimposed on the optical signal as follows. Optical signals used in telecommunications usually have a frame structure with a certain period (for example, a period of 125 μs). Using the first bit of the frame as the reference phase,
By putting the phase difference information in the data area, the reference phase signal and the phase difference information can be transmitted by the optical signal. SDH (Synchronous), an international standard format for communication signals
(ous Digital Hierarchy) signal, an even better effect can be obtained. That is, in the SDH signal, an area independent of the main signal channel (the area is
By placing the phase difference information in this area, the reference phase signal and the phase difference information can be transmitted without interfering with the main signal.
This makes it possible to transmit the SDH main signal and the signal for phase synchronization simultaneously, which is advantageous in terms of economy.

FIG. 5 is a block diagram showing another configuration example of the phase synchronization system according to the second embodiment of the present invention. The master device transmitting section 10 'and the slave device receiving section 20' shown in this figure are the same as those shown in FIG. In this figure, the slave unit transmitting / receiving unit 40 ′ includes a master unit transmitting unit 10 ′ excluding the reference oscillator 11 and the slave unit receiving unit 2.
0 '. Slave device transceiver 4
At 0 ′, the phase signal a ′ obtained by the phase adjustment unit 45 is input to the optical transmitters 50 ′ and 52 and the phase comparison unit 53 as the reference synchronization signal a. Note that in the phase synchronization system shown in FIG. 5, there is only one slave device transmitting / receiving unit 40 ',
By performing the same connection in multiple stages, a phase synchronization system having a plurality of slave device transmission / reception units 40 'can be constructed.

§3. Third Embodiment FIG. 6 is a block diagram showing a configuration example of a phase synchronization system according to a third embodiment of the present invention. The master device transmitting section 10 and the slave device receiving section 20 shown in this figure are the same as those shown in FIG. In this figure, main device transmitting section 1
0 and the relay device 30 are connected via the optical fiber 1-1, and the relay device 30 and the slave device receiver 20 are connected via the optical fiber 1-2.

In the repeater 30, the optical fiber 1-1
The optical signal with a wavelength of 1.31 μm input from the optical multiplexer / demultiplexer 3
The optical signal is transmitted to the optical fiber 1-2 via the optical repeater 32-1 and the optical multiplexer / demultiplexer 31-2. An optical signal having a wavelength of 1.55 μm input from the optical fiber 1-1 is supplied to an optical multiplexer / demultiplexer 31-1, an optical switch 33-1 and an optical repeater 32-.
2. The light is sent to the optical fiber 1-2 via the optical switch 33-2 and the optical multiplexer / demultiplexer 31-2. An optical signal having a wavelength of 1.55 μm input from the optical fiber 1-2 is transmitted to the optical multiplexer / demultiplexer 31-2, the optical switch 33-2, and the optical repeater 32-.
3. The light is transmitted to the optical fiber 1-1 via the optical switch 33-1 and the optical multiplexer / demultiplexer 31-1. Information transfer device 35
Receives the switching control signal e and the phase difference information f from the information transfer device 19 of the main device transmitting unit 10, inputs the switching control signal e to the control device 34, and receives the switching control signal e and the phase difference information f. f to the slave device receiver 20.
The control device 34 switches the optical switches 33-1 and 33-2 simultaneously based on the switching control signal e.

The phase comparing section 14 of the main apparatus transmitting section 10 compares the phase difference between the reference phase signal a and the phase signal b, and outputs the obtained phase difference information f via the information transfer devices 19, 35 and 29. Is transferred to the phase adjustment unit 25 of the slave device reception unit 20. The phase comparison unit 26 of the slave device receiving unit 20 compares the phase difference between the phase signal c and the phase signal d, and supplies the obtained phase difference information g to the phase adjustment unit 25. As a result, the slave device receiver 20
The phase adjustment unit 25 adjusts the phase of the phase signal c based on the phase difference information f and g, and generates a phase signal a ′ having the same phase as the reference phase signal a of the main device transmission unit 10. The phase adjustment unit 25 can be easily realized by a combination of a programmable counter and a phase locked oscillator.

In the present embodiment, the optical switch 16 of the main unit transmitting unit 10 and the optical switches 33-1 and 33 of the relay device 30 are used.
-2, by simultaneously switching the optical switch 23 of the slave device receiver 20, the master device transmitter 10 and the slave device receiver 2
Two states can be formed as the state of the optical transmission line between 0 and 1 as in the first embodiment.

That is, in the state 1, the reference phase signal a
Is transmitted as an optical signal having a wavelength of 1.31 μm from the main device transmitter 10 to the slave device receiver 20 via the relay device 30.
An optical signal having a wavelength of 1.55 μm is returned from the slave device receiving unit 20 to the master device transmitting unit 10 via the relay device 30, and becomes a phase signal b. Here, the delay time due to the transmission from the main unit transmitting unit 10 to the slave unit receiving unit 20 for the light of wavelength 1.31 μm is T1, and the slave unit receiving unit 20 for the light of wavelength 1.55 μm
The delay time due to the transmission from the transmitter to the main unit transmitter 10 is represented by T2
Then, in state 1, the phase difference Δ1 measured by the phase comparison unit 14 of the main device transmission unit 10 is Δ1 = T1 + T2.

In the state 2, the reference phase signal a is transmitted at 1.31 μm wavelength and 1.55 μm wavelength light from the main unit transmitting unit 10 to the slave unit receiving unit 20 via the relay unit 30 at the same time. Since the transmission delay time due to the optical fiber does not depend on the light transmission direction if the wavelength is the same, the phase difference Δ2 measured by the phase comparison unit 26 of the slave device receiving unit 20 in state 2 is Δ2 = T1 −T2.

As described above, the optical switches 16, 33-1, 3
3-2 and 23 are switched to measure both the phase difference △ 1 and the phase difference △ 2, and the phase difference information f indicating the phase difference Δ1 and the phase difference g indicating the phase difference Δ2 are Phase adjuster 25
The delay time T1 can be accurately obtained by performing the calculation of T1 = (△ 1 + △ 2) / 2. Phase adjuster 25 of slave device receiver 20
Adjusts the phase of the phase signal c based on the delay time T1 to generate a phase signal a 'having the same phase as the reference phase signal a of the main device transmitter 10.

In the present embodiment, the main unit transmitting unit 10
And an example in which the slave device receiving unit 20 is connected via one relay device 30. However, since the distance between the master device transmitting unit 10 and the slave device receiving unit 20 is long, Even when two or more relay devices 30 are arranged, high-precision phase synchronization can be performed similarly.

Also, in the present embodiment, the main unit transmitting unit 10
Although the example in which the relay device 30 is arranged in the phase synchronization system including the slave device receiving unit 20 and the master device transmitting unit 10, the slave device receiving unit 20, and the slave device transmitting / receiving unit 40 as shown in FIG. It is also possible to arrange the relay device 30 in a phase synchronization system comprising

§4. Fourth Embodiment FIG. 7 is a block diagram illustrating a configuration example of a phase synchronization system according to a fourth embodiment of the present invention. The master device transmitting section 10 'and the slave device receiving section 20' shown in this figure are the same as those shown in FIG. The optical transmitter 12 'of the main unit transmitter 10' has a wavelength of 1.31 μm modulated by the reference phase signal a.
Through the optical multiplexer / demultiplexer 15 to the optical fiber 1-
1, the switching control signal e and the phase difference information f
The optical fiber 1-1 is superimposed on the optical signal having a wavelength of 1.31 μm.
To send to.

In response to this, the optical repeater 32-1 'of the repeater 30' is provided with a demultiplexing function for extracting the switching control signal e from the optical signal having the wavelength of 1.31 μm. Further, the optical receiver 22 'of the slave device receiver 20' is provided with a separating function for extracting the switching control signal e and the phase difference information f from the optical signal having the wavelength of 1.31 μm. As a result, the switching control signal e and the phase difference information f are transmitted using the optical fibers 1-1 and 1-2, so that the information transfer device 1 shown in the third embodiment can be used.
The transfer path between 9, 29, 35 and the information transfer device becomes unnecessary.

Further, in the present embodiment, the main unit transmitting section 1
FIG. 5 shows an example in which the relay device 30 ′ is arranged in the phase synchronization system including the 0 ′ and the slave device receiving unit 20 ′.
The main device transmitting section 10 'and the slave device receiving section 20' as shown in FIG.
It is also possible to arrange the relay device 30 'in a phase synchronization system composed of the slave device transmitting and receiving unit 40'.

In the first to fourth embodiments, two wavelengths in the 1.5 μm band, for example, 1.54 μm
Optical signals of two wavelengths, m and 1.56 μm, may be used. In this case, the configuration of the fifth embodiment described below can be adopted.

§5. Fifth Embodiment FIG. 8 is a block diagram illustrating a configuration example of a phase synchronization system according to a fifth embodiment of the present invention. The feature of the present invention is that, as shown in FIG. 8, an erbium-doped fiber 36, an excitation light source 37, and an optical coupler 38 for inputting the excitation light emitted from the excitation light source 37 to the Erbium-doped fiber 36 as a repeater 30 ″. Erbium-doped fiber 3 as an optical signal.
6 is that optical signals having wavelengths of 1.54 μm and 1.56 μm, which can be amplified, are used. On the other hand, the optical transmitter 12 ′ of the main unit transmitting unit 10 ′ transmits an optical signal having a wavelength of 1.54 μm, the optical transmitter 13 of the main unit transmitting unit 10 ′ transmits an optical signal having a wavelength of 1.56 μm, The optical receiver 17 of the main unit transmitter 10 'has a wavelength of 1.56μ.
m optical signals are received. On the other hand, the optical receiver 22 'of the slave receiver 20' receives an optical signal of 1.54 μm wavelength, the optical receiver 24 of the slave receiver 20 'receives an optical signal of 1.56 μm, and The optical transmitter 27 of the unit 20 'has a wavelength of 1.56.
Transmit an optical signal of μm. Regardless of which direction an optical signal having a wavelength of 1.54 μm or 1.56 μm passes,
Since 0 "amplifies the optical signal, there is no need to provide an optical multiplexer / demultiplexer or an optical switch in the repeater 30".

FIG. 9 is a block diagram showing another configuration example of the phase synchronization system according to the fifth embodiment of the present invention. The main device transmitting section 10 'and the relay device 30 "shown in FIG.
The slave device receiving section 20 'is the same as that shown in FIG. Further, in FIG.
0 'is a combination of the main unit transmitting unit 10' excluding the reference oscillator 11 and the slave unit receiving unit 20 '. In the slave device transmitting / receiving section 40 ', the phase signals a' obtained by the phase adjusting section 45 are used as the reference synchronization signals a, and the optical transmitters 50 ', 5'
2 and the phase comparator 53. Although the phase synchronization system shown in FIG. 9 has only one slave device transmitting / receiving section 40 ', a phase synchronization system having a plurality of slave device transmitting / receiving sections 40' is constructed by performing similar connections over multiple stages. You can also.

§6. Supplement Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the embodiment, and there may be a design change or the like without departing from the gist of the present invention. Even this is included in the present invention. The present invention can be used for systems other than optical fiber transmission lines and optical signals. For example, the present invention provides a system that performs phase synchronization using an optical signal that propagates in the atmosphere, a system that performs phase synchronization between an artificial satellite and the ground using radio waves, and that propagates radio waves in the ionosphere, and the like. It is also applicable to:

[0057]

According to the above invention, in the state 1, the reference phase signal is transmitted from the master device to the slave device by using the optical signal of the wavelength λ1,
The phase signal is returned from the slave device to the master device as an optical signal having the wavelength λ2, so that the phase signal reciprocates between the master device and the slave device. The phase comparator of the main device compares the phase of the reference phase signal with the returned phase signal. The phase difference obtained at this time is the sum of the delay time at the wavelength λ1 of the optical transmission line and the delay time at the wavelength λ2.

On the other hand, in the state 2, the reference phase signal is transmitted from the master device to the slave device using the optical signal of the wavelength λ1 and the optical signal of the wavelength λ2. The phase comparator of the slave device compares the phases of the phase signals separated from the optical signals of the respective wavelengths. The phase difference obtained at this time is the difference between the delay time at the wavelength λ1 of the optical transmission line and the delay time at the wavelength λ2.

When the sum and difference of the two unknowns are found, the values of the two unknowns can be calculated. Therefore, from the sum obtained in the above state 1 and the difference obtained in the above state 2, the value at the wavelength λ1 of the optical transmission line is obtained. The delay time and the delay time at the wavelength λ2 can be measured accurately.

Therefore, even if there is a difference in the delay time (wavelength dispersion) due to the difference in the wavelength of the optical transmission line, the delay time for each wavelength can be measured accurately.
High-precision phase synchronization between the master device and the slave device can be realized. Further, if the present invention is applied to a reference clock distribution network in a digital communication network, clock distribution without the influence of delay time due to propagation of a clock distribution transmission line can be realized, and the accuracy of the reference clock distribution network can be easily maintained. In the conventional phase synchronization system (see FIG. 10), two transmission media must be used. This is not only from the viewpoint of the accuracy of phase synchronization but also from the viewpoint of the use efficiency and economy of the transmission medium. Was also a problem. The present invention is capable of realizing high-precision phase synchronization with a single transmission medium, and is therefore more economical than the conventional phase synchronization system.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a phase synchronization system according to a first embodiment of the present invention.

FIG. 2A is a diagram illustrating a state 1 of the phase-locked system according to the first embodiment of the present invention, and FIG. 2B is a diagram illustrating a state 2 of the phase-locked system.

FIG. 3 is a block diagram illustrating another configuration example of the phase synchronization system according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration example of a phase synchronization system according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing another configuration example of the phase synchronization system according to the second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration example of a phase synchronization system according to a third embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration example of a phase synchronization system according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration example of a phase synchronization system according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing another configuration example of the phase synchronization system according to the fifth embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration example of a conventional phase synchronization system.

FIG. 11 is a block diagram illustrating a configuration example of a wavelength division multiplexing bidirectional communication system.

[Explanation of symbols]

10: main device transmission unit, 11: reference oscillator, 12,
13, 27 ... optical transmitter, 14, 26 ... phase comparator, 15, 21 ... optical multiplexer / demultiplexer, 16, 23 ... optical switch, 17, 22, 24 ... optical receiver, 18, 28
... Control device, 19, 29 ... Information transfer device, 20 ...
... Slave device receiving unit, 25 ... Phase adjusting unit

Continuation of the front page (56) References JP-A-3-223611 (JP, A) Jun Imai, Masami Kihara, Sub-nanosecond time transmission system using wavelength multiplexed bidirectional communication, Proc. Japan, The Institute of Electronics, Information and Communication Engineers, August 15, 1995, VOL. 1995, NO. Society B2, 378 Atsushi Imaoka and Masami Kihara, Long-Term Propagation Delay Characteristics of Telecommunications Lens, International Communications, USA. 41, NO. 5,653-656 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 H04L 7/00

Claims (15)

(57) [Claims] An optical signal is received from an optical fiber connected to a transmission device provided in a master device or a slave device, and an optical signal of wavelength λ1 and an optical signal of wavelength λ2 are separated from the received optical signal. An optical multiplexer / demultiplexer (21); and a first optical receiver (2) for separating a first phase signal (c) from the optical signal of wavelength λ1 separated by the optical multiplexer / demultiplexer (21).
2) and a second optical receiver (2) for separating a second phase signal (d) from the optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (21).
4), the first phase signal (c) and the second phase signal (d)
, That is, a first delay time (T) until the optical signal of the wavelength λ1 reaches the transmitting apparatus from the transmitting apparatus.
1) and the difference (T1-T2) between the second delay time (T2) until the optical signal of the wavelength λ2 reaches the transmission device from the transmission device.
2), and a phase comparator (26) for outputting second phase difference information (g) representing the phase difference, and generating an optical signal of wavelength λ2 modulated by the first phase signal (c). An optical transmitter (27) for transmitting the optical signal to the optical fiber via the optical multiplexer / demultiplexer (21), and an optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (21). State of input to the second optical receiver (24) (state 2)
An optical switch (23) for switching between a state (state 1) in which the optical signal of wavelength λ2 generated by the optical transmitter (27) is input to the optical multiplexer / demultiplexer (21); and the optical switch (23). And a switching control signal (e) for switching the state of (i) and a first (T1 + T2) representing the sum of the first delay time (T1) and the second delay time (T2).
An information transfer unit (29) that receives the phase difference information (f) from the outside, and a switching control signal (e) received by the information transfer unit (29).
A controller (28) for controlling the state of the optical switch (23) based on the value (T1 + T2) represented by the first phase difference information (f) and the second phase difference information (g). A delay time calculating unit (25) for calculating the first delay time (T1) by dividing the sum of the value (T1-T2) by 2 and a delay time calculated by the delay time calculating unit (25) (T1)
The phase adjustment unit (25) that generates a phase signal (a ′) synchronized with the reference phase signal (a) generated by the transmitting device by adjusting the phase of the first phase signal (c) based on A receiving device for a phase-locked system. 2. A reference oscillator (11) for generating a reference phase signal (a), and a reference phase signal (a) generated by the reference oscillator (11).
A first optical transmitter (12) for generating an optical signal having a wavelength λ1 modulated by a reference phase signal (a) generated by the reference oscillator (11)
A second optical transmitter (13) for generating an optical signal having a wavelength λ2 modulated by the first optical transmitter, an optical signal having a wavelength λ1 generated by the first optical transmitter (12), and the second optical transmitter ( 13) multiplexes the generated optical signal with the wavelength λ2, sends the multiplexed optical signal to the optical fiber to which the receiving device provided in the slave device is connected, and converts the optical signal from the optical fiber. An optical multiplexer / demultiplexer (1) that receives and separates the optical signal of the wavelength λ2 from the received optical signal.
5), an optical receiver (17) for separating a phase signal (b) from an optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (15), the reference phase signal (a) and the phase signal (b) ), That is, a first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving device from the present device and the optical signal of the wavelength λ2 reaches the present device from the receiving device. A phase comparison unit (14) for obtaining a sum (T1 + T2) of a second delay time (T2) until the first light is output and outputting first phase difference information (f) representing the phase difference; A state where the optical signal of wavelength λ2 generated by the transmitter (13) is input to the optical multiplexer / demultiplexer (15) (state 2).
An optical switch (16) for switching between a state (state 1) in which the optical multiplexer / demultiplexer (15) inputs the separated optical signal of wavelength λ2 to the optical receiver (17); and the optical switch (16). The control unit (1) controls the state of the control unit and outputs a switching control signal (e) indicating the control state.
8) an information transfer unit for transmitting the switching control signal (e) output by the control unit (18) and the first phase difference information (f) output by the phase comparison unit (14) to the outside (19) A transmission device for a phase synchronization system, comprising: 3. A reference phase signal (a) inputted from outside
A first optical transmitter (12) for generating an optical signal of wavelength λ1 modulated by the first optical transmitter; and a second optical transmitter (13) for generating an optical signal of wavelength λ2 modulated by the reference phase signal (a). ), The optical signal of wavelength λ1 generated by the first optical transmitter (12) and the optical signal of wavelength λ2 generated by the second optical transmitter (13) are multiplexed and multiplexed. An optical coupler that sends an optical signal to an optical fiber connected to a receiving device provided in a slave device, receives an optical signal from the optical fiber, and separates the optical signal of the wavelength λ2 from the received optical signal. Corrugator (1
5), an optical receiver (17) for separating a phase signal (b) from an optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (15), the reference phase signal (a) and the phase signal (b) ), That is, a first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving device from the present device and the optical signal of the wavelength λ2 reaches the present device from the receiving device. A phase comparison unit (14) for obtaining a sum (T1 + T2) of a second delay time (T2) until the first light is output and outputting first phase difference information (f) representing the phase difference; A state where the optical signal of wavelength λ2 generated by the transmitter (13) is input to the optical multiplexer / demultiplexer (15) (state 2).
An optical switch (16) for switching between a state (state 1) in which the optical multiplexer / demultiplexer (15) inputs the separated optical signal of wavelength λ2 to the optical receiver (17); and the optical switch (16). The control unit (1) controls the state of the control unit and outputs a switching control signal (e) indicating the control state.
8) an information transfer unit for transmitting the switching control signal (e) output by the control unit (18) and the first phase difference information (f) output by the phase comparison unit (14) to the outside (19) A transmission device for a phase synchronization system, comprising: 4. An optical signal is received from an optical fiber to which a transmitting device provided in a master device or a slave device is connected, and an optical signal of wavelength λ1 and an optical signal of wavelength λ2 are separated from the received optical signal. An optical multiplexer / demultiplexer (21); a first phase signal (c), a switching control signal (e), and first phase difference information (f) from the optical signal of wavelength λ1 separated by the optical multiplexer / demultiplexer (21). ) And a first optical receiver (2)
2 ′), and a second optical receiver (2) that separates a second phase signal (d) from the optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (21).
4), the first phase signal (c) and the second phase signal (d)
, That is, a first delay time (T) until the optical signal of the wavelength λ1 reaches the transmitting apparatus from the transmitting apparatus.
1) and the difference (T1-T2) between the second delay time (T2) until the optical signal of the wavelength λ2 reaches the transmission device from the transmission device.
2), and a phase comparator (26) for outputting second phase difference information (g) representing the phase difference, and generating an optical signal of wavelength λ2 modulated by the first phase signal (c). An optical transmitter (27) for transmitting the optical signal to the optical fiber via the optical multiplexer / demultiplexer (21), and an optical signal of wavelength λ2 separated by the optical multiplexer / demultiplexer (21). State of input to the second optical receiver (24) (state 2)
An optical switch (23) for switching between a state (state 1) of inputting the optical signal of wavelength λ2 generated by the optical transmitter (27) to the optical multiplexer / demultiplexer (21); and the first optical reception. A control unit (28) for controlling the state of the optical switch (23) based on the switching control signal (e) separated by the device (22 '), and a value represented by the first phase difference information (f) ( T1 + T2) and the sum of the value (T1−T2) represented by the second phase difference information (g) divided by 2 to obtain the first delay time (T1). The delay time (T1) obtained by the delay time calculation unit (25)
The phase adjustment unit (25) that generates a phase signal (a ′) synchronized with the reference phase signal (a) generated by the transmitting device by adjusting the phase of the first phase signal (c) based on A receiving device for a phase synchronization system. 5. A reference oscillator (11) for generating a reference phase signal (a), and a reference phase signal (a) generated by the reference oscillator (11).
A first optical transmitter (12 ') for generating an optical signal having a wavelength of λ1 modulated by the reference oscillator (11); and a reference phase signal (a) generated by the reference oscillator (11).
A second optical transmitter (13) for generating an optical signal of a wavelength λ2 modulated by: an optical signal of a wavelength λ1 generated by the first optical transmitter (12 ′) and the second optical transmitter Wavelength λ2 generated by (13)
The optical signal is transmitted to an optical fiber to which a receiving device provided in a slave device is connected, and an optical signal is received from the optical fiber. An optical multiplexer / demultiplexer (15) for separating the optical signal of the wavelength λ2 from the signal; and an optical receiver (17) for separating the phase signal (b) from the optical signal of the wavelength λ2 separated by the optical multiplexer / demultiplexer (15). ) And a phase difference between the reference phase signal (a) and the phase signal (b), that is, a first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving apparatus from the present apparatus. (T1 + T2) of a second delay time (T2) until the optical signal of the wavelength λ2 reaches the present device from the receiving device, and first phase difference information (f) representing the phase difference And a light having a wavelength of λ2 generated by the second optical transmitter (13). A state where a signal is input to the optical multiplexer / demultiplexer (15) (state 2)
An optical switch (16) for switching between a state (state 1) in which the optical multiplexer / demultiplexer (15) inputs the separated optical signal of wavelength λ2 to the optical receiver (17); and the optical switch (16). The control unit (1) controls the state of the control unit and outputs a switching control signal (e) indicating the control state.
8), the switching control signal (e) output from the control unit (18), and the first phase difference information (f) output from the phase comparison unit (14), by the first optical transmitter. And a superimposing means (12 ') for superimposing the optical signal of the wavelength λ1 generated by (12'). 6. A reference phase signal (a) input from outside
A first optical transmitter (12 ') that generates an optical signal of wavelength λ1 modulated by the second optical transmitter (12 ′) that generates an optical signal of wavelength λ2 that is modulated by the reference phase signal (a); 13), an optical signal of wavelength λ1 generated by the first optical transmitter (12 ′) and a wavelength λ2 generated by the second optical transmitter (13).
The optical signal is transmitted to an optical fiber to which a receiving device provided in a slave device is connected, and an optical signal is received from the optical fiber. An optical multiplexer / demultiplexer (15) for separating the optical signal of the wavelength λ2 from the signal; and an optical receiver (17) for separating the phase signal (b) from the optical signal of the wavelength λ2 separated by the optical multiplexer / demultiplexer (15). ) And a phase difference between the reference phase signal (a) and the phase signal (b), that is, a first delay time (T1) until the optical signal of the wavelength λ1 reaches the receiving apparatus from the present apparatus. (T1 + T2) of a second delay time (T2) until the optical signal of the wavelength λ2 reaches the present device from the receiving device, and first phase difference information (f) representing the phase difference And a light having a wavelength of λ2 generated by the second optical transmitter (13). A state where a signal is input to the optical multiplexer / demultiplexer (15) (state 2)
An optical switch (16) for switching between a state (state 1) in which the optical multiplexer / demultiplexer (15) inputs the separated optical signal of wavelength λ2 to the optical receiver (17); and the optical switch (16). The control unit (1) controls the state of the control unit and outputs a switching control signal (e) indicating the control state.
8), the switching control signal (e) output from the control unit (18), and the first phase difference information (f) output from the phase comparison unit (14), by the first optical transmitter. And a superimposing means (12 ') for superimposing the optical signal of the wavelength λ1 generated by (12'). 7. The first optical transmitter (12) according to claim 3, wherein the phase signal (a ′) generated by the phase adjustment unit (25) according to claim 1 is used as a reference phase signal (a). The receiving device according to claim 1 and the transmitting device according to claim 3 are combined into one transmitting / receiving device by inputting to the second optical transmitter (13) and the phase comparing unit (14). Transmitter / receiver for a phase synchronization system. 8. The first optical transmitter (12 ′) according to claim 6, wherein the phase signal (a ′) generated by the phase adjustment unit (25) according to claim 4 is used as a reference phase signal (a). And the second optical transmitter (13) and the phase comparison unit (14), whereby the receiving device according to claim 4 and the transmitting device according to claim 6 are combined into one transmitting / receiving device. Transmitting and receiving apparatus of a phase synchronization system. 9. A phase synchronization system, wherein the transmission device according to claim 2 and the reception device according to claim 1 are connected by an optical fiber. 10. A phase synchronization system, wherein the transmitting device according to claim 5 and the receiving device according to claim 4 are connected by an optical fiber. 11. A phase synchronization system comprising: a transmitting device according to claim 2, at least one transmitting / receiving device according to claim 7, and a receiving device according to claim 1, connected in tandem by optical fibers. 12. A phase synchronization system comprising: a transmitting device according to claim 5, one or more transmitting / receiving devices according to claim 8, and a receiving device according to claim 4, connected in tandem by optical fibers. 13. An optical signal is received from an optical fiber to which a transmission device provided in a master device or a slave device is connected, and an optical signal of wavelength λ1 and an optical signal of wavelength λ2 are separated from the received optical signal. A first optical multiplexer / demultiplexer (31-1), and a wavelength λ1 separated by the first optical multiplexer / demultiplexer (31-1).
And a wavelength .lambda.2 separated by the first optical repeater (32-1) for relaying the optical signal from the first optical multiplexer / demultiplexer (31-1).
A second optical repeater (32-2) for relaying the optical signal of the second optical repeater (32-2), and an optical signal of wavelength λ1 relayed by the first optical repeater (32-1) and the second optical repeater (32- 2) multiplexes the relayed optical signal of wavelength λ2 and sends the multiplexed optical signal to an optical fiber connected to a receiving device provided in a slave device different from the slave device. A second optical multiplexer / demultiplexer (31-2) for receiving an optical signal from an optical fiber and separating the optical signal of the wavelength λ2 from the received optical signal; and a second optical multiplexer / demultiplexer (31-2). ) Separated wavelength λ2
The third optical repeater (32-3) for relaying the optical signal of the above (2) and the wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1).
Is input to the second optical repeater (32-2),
And the wavelength λ relayed by the second optical repeater (32-2).
State (state 2) in which the second optical signal is input to the second optical multiplexer / demultiplexer (31-2), and the state where the second optical signal is input to the second optical multiplexer / demultiplexer (31-2).
2) inputs the separated optical signal of wavelength λ2 to the third optical repeater (32-3), and outputs the optical signal to the third optical repeater (32-3).
-3) an optical switch (33-1, 33-2) for switching between a state (state 1) of inputting the optical signal of wavelength λ2 relayed to the first optical multiplexer / demultiplexer (31-1); A switching control signal (e) and the first phase difference information (f) are received from the transmitting device, and the switching control signal (e) and the first phase difference information (f) are transmitted to the receiving device. An information transfer unit (35); and a switching control signal (e) received by the information transfer unit (35).
And a control unit (34) for controlling a state of the optical switch (33-1, 33-2) based on the relay device. Phase synchronization system placed. 14. An optical signal received from an optical fiber connected to a transmission device provided in a master device or a slave device, and an optical signal having a wavelength λ1 and an optical signal having a wavelength λ2 are separated from the received optical signal. A first optical multiplexer / demultiplexer (31-1), and a wavelength λ1 separated by the first optical multiplexer / demultiplexer (31-1).
And a first optical repeater (32-) that separates the switching control signal (e) from the optical signal of the wavelength λ1.
1 ′) and the wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1).
A second optical repeater (32-2) for relaying the optical signal of the first optical repeater, and a wavelength λ1 relayed by the first optical repeater (32-1 ').
And the optical signal of wavelength λ2 relayed by the second optical repeater (32-2) is multiplexed, and the multiplexed optical signal is provided in a slave device different from the slave device. A second optical multiplexer / demultiplexer (31-2) for transmitting an optical signal to the optical fiber connected to the receiving device, receiving an optical signal from the optical fiber, and separating the optical signal of the wavelength λ2 from the received optical signal; And the wavelength λ2 separated by the second optical multiplexer / demultiplexer (31-2).
The third optical repeater (32-3) for relaying the optical signal of the above (2) and the wavelength λ2 separated by the first optical multiplexer / demultiplexer (31-1).
Is input to the second optical repeater (32-2),
And the wavelength λ relayed by the second optical repeater (32-2).
State (state 2) in which the second optical signal is input to the second optical multiplexer / demultiplexer (31-2), and the state where the second optical signal is input to the second optical multiplexer / demultiplexer (31-2).
2) inputs the separated optical signal of wavelength λ2 to the third optical repeater (32-3), and outputs the optical signal to the third optical repeater (32-3).
-3) an optical switch (33-1, 33-2) for switching between a state (state 1) of inputting the optical signal of wavelength λ2 to the first optical multiplexer / demultiplexer (31-1); Based on the switching control signal (e) separated by the first optical repeater (32-1 ′), the optical switch (33-1, 3-3)
13. A phase synchronization system in which a repeater including a control unit (34) for controlling the state of 3-2) is arranged between the respective devices according to claim 10 or 12. 15. An optical signal received from an optical fiber connected to a transmission device provided in a master device or a slave device, the received optical signal is amplified by pumping light, and the amplified optical signal is sent to the slave device. A receiving device provided in a slave device different from the device transmits the optical signal to an optical fiber connected thereto, and the receiving device receives an optical signal from the connected optical fiber, and amplifies the received optical signal by pumping light. An optical amplifying unit (36) for transmitting the amplified optical signal to an optical fiber to which the transmitting device is connected; an excitation light source (37) for emitting the excitation light; and an excitation light source (37). 13. A phase synchronization system in which a repeater comprising pump light source input means (38) for inputting pump light to the optical amplifying means (36) is provided between the devices according to claim 10 or 12. .