WO2008068842A1 - Optical repeater of optical submarine cable system and optical submarine cable system equipped with that optical repeater - Google Patents

Abstract

An optical repeater in which the possibility of entirely interrupting communication is low even when a feeding current decreases, and an optical submarine cable system in which the possibility of entirely interrupting communication is low because that optical repeater is provided. An optical repeater in which communication is prevented from being disrupted partially or entirely even when a feeding current decreases by stopping power supply to a part of a plurality of optical amplifiers provided in the optical repeater and/or to a part of a plurality of pump lasers provided in the optical amplifier, and an optical submarine cable system equipped with that optical repeater are achieved.

Description

 Specification

 Optical repeater of optical submarine cable system and optical submarine Cape Nore system including the optical repeater

 Technical field

 [0001] The present invention relates to an optical repeater of an optical submarine cable system and an optical submarine cable system including the optical repeater. More specifically, the present invention relates to an optical repeater of an optical submarine cable system and a power feeding method of an optical submarine cable system including the optical repeater.

 Background art

 [0002] An optical submarine cable system includes an optical fiber that propagates an optical signal carrying data, an optical repeater that relays the optical signal, and an internal conductor that energizes a feeding current for driving the optical repeater. Using the optical submarine cable installed inside, the optical signal transmitted from the land transmission device is relayed using the optical repeater, and the digital data is transmitted by receiving it at the opposite land transmission device.

 [0003] In an optical repeater feeding system used in an optical submarine cable system, generally, a direct-current voltage having a positive or negative polarity is applied to each optical submarine cable from the opposite land station. As a result, a direct current is supplied to the optical submarine cable system. In the optical repeater, the optical amplifier in the optical repeater is driven using the DC voltage generated across the resistor in the power circuit.

 FIG. 1 is a conceptual diagram of an optical submarine cable system. A power supply device 3 is installed at each opposing land station, and a direct current is applied to an optical submarine cable system including a plurality of optical repeaters 2. The current circulates in a closed circuit between the inner conductor of the optical submarine cable and seawater. Here, the DC current to be fed is controlled by the potential difference between both feeding devices 3.

 FIG. 2 is a schematic configuration diagram of the optical repeater 2. The power supply circuit 5 for obtaining a DC voltage from the current applied to the optical submarine cable and one or a plurality of optical amplifiers 4 for amplifying / relaying the optical fiber signal are loaded inside.

[0006] The optical amplifier 4 is an erbium-doped fiber 8 that directly amplifies signal light transmitted through the optical submarine cable system, and pumps it with pump light to generate an optical amplification effect. Multiple pump lasers 7, LD (Laser Diode) drive circuit 6 for driving the pump laser, and the function of combining signal light, pump light, and pump light, and blocking unnecessary wavelength light It consists of multiple optical components (not shown) and force. Here, the pump laser 7 has a plurality of redundant configurations because the influence on the signal light transmission quality is affected by the design of the system even if a part of the laser element with relatively low reliability of the laser element fails. This is to make it within an allowable range.

 [0007] In the normal power supply state, as shown in Fig. 3 (a), the power supply voltage of both power supply devices 3 is balanced and the virtual potential is zero near the middle point of the optical submarine cable system. is there. Here, the vertical axis represents the potential, and the horizontal axis represents the distance between land stations. If the cable grounding fault, that is, the cable sheath is damaged as shown in Fig. 3 (b), the inner conductor comes into contact with seawater and becomes electrically conductive, the power feeding device 3 is connected as shown in Fig. 3 (c). Each power supply voltage is automatically adjusted to keep the slope of the graph, that is, the current value constant (see Non-Patent Documents 1 and 2).

 [0008] Non-Patent Document 1: Noboru Oyama / Moji Kuwahara “Optical Submarine Cable Communication”, KDDI Engineering and Consulting (1991)

 Non-Patent Document 2: Akiba / Nishi "Submarine Cable Networks Systems", N'Ti'Ti Qoris (2001)

 Disclosure of the invention

 Problems to be solved by the invention

However, in the conventional system described above, if a cable ground fault occurs at a location away from the center as shown in FIG. 4, it is possible to adjust the power supply voltage of both stations to keep the current constant. As a result, the output voltage of the power supply device on the side where the failure point is far from has reached its peak, and the optical repeater cannot be driven due to insufficient power supply current.

[0010] In general, in an optical submarine cable system, there is an upper limit to the supply voltage from the land station due to limitations on the withstand voltage of the optical submarine cable, optical repeater, or connection and the convenience of the design of the power supply device. In particular, in the case of a long-distance optical submarine cable system, or in the case of an optical submarine cable system that has a small diameter and low withstand voltage and uses an optical submarine cable, the power supply voltage from one side alone is necessary for an optical repeater There is a case where the feeding current cannot be supplied. in this case, Even if there is no damage to the optical fiber, the current is not supplied to the optical repeater due to the location of the cable grounding failure, and communication is completely cut off. Usually, the repair of the submarine part of the optical submarine cable requires a period of one week or more. During this period, the communication was interrupted, causing serious damage.

 [0011] The present invention provides an optical repeater that is unlikely to be completely disconnected even when the power supply current is reduced due to a cable ground failure or the like, and the communication can be completely disconnected by including the optical repeater. An object is to provide an optical submarine cable system with low performance.

 Means for solving the problem

 In order to achieve the above object, an optical repeater of an optical submarine cable system according to the present invention is applied from a plurality of pump lasers for amplifying signal light transmitted from a land transmission device and a station on land. A power supply circuit for supplying current to the pump laser using a direct current supply current as a power source, pump laser power saving means for stopping supply of current to some pump lasers as the power supply current decreases, including.

 [0013] Further, the optical repeater of the optical submarine cable system according to the present invention further includes a plurality of optical amplifiers, each pump laser belongs to one of the optical amplifiers, and the pump laser power saving means includes a reduction in power supply current. Accordingly, it is preferable to stop supplying current to all pump lasers of some optical amplifiers.

 [0014] The power supply circuit further includes a resistor for generating a voltage for supplying a current to the pump laser at both ends, each pump laser is connected to the both ends of the resistor, and the pump laser power saving means includes one It is preferable to cut the resistance of the pump laser of the part.

 [0015] The pump laser power saving means preferably further reduces the resistance value of a resistor that generates a voltage at both ends for supplying a current to the pump laser in the power supply circuit.

 In order to achieve the above object, an optical submarine cable system according to the present invention includes the optical repeater described above.

 The invention's effect

[0017] According to the present invention, an optical repeater for an optical submarine cable is connected to a part of a plurality of optical amplifiers provided in the optical repeater when a direct current supplied from a land station is reduced. A power supply circuit that stops power supply is provided. Or Sarako, in the same case, in the optical amplifier Are equipped with a power supply circuit that stops power supply to some of the pump lasers. This makes it possible to realize an optical submarine cable system with a low possibility of disrupting some or all communications even when the power supply current to the optical repeater is reduced due to a cable ground fault or the like.

 [0018] When some of the optical amplifiers are stopped, communication of other fiber pairs is maintained by the remaining optical amplifiers, and the communication service can be maintained by moving the commercial line there.

 In addition, when some of the pump lasers are stopped, it is possible to maintain the drive of the optical amplifier with the light output of the remaining pump lasers. In this case, if the degree of transmission quality degradation of the entire optical submarine cable system due to the decrease in the output of the optical amplifier is within the margin of the system design, the influence on the communication service can be avoided.

 [0020] In particular, in long-distance optical submarine cable systems and optical submarine cable systems using relatively low insulation voltage underwater equipment, there is a possibility of continuing communication even when the cable grounding fault is off the center. Can be increased.

 [0021] Further, by adopting the present invention, it is not necessary to increase the supply voltage of the power supply device and the withstand voltage of the submarine equipment in order to increase resistance to cable ground faults, or land stations that are normally required. By omitting the redundant configuration of the power supply apparatus installed in the network, it is possible to provide a safe and inexpensive optical submarine cable system.

 Brief Description of Drawings

FIG. 1 is a conceptual diagram of an optical amplifying submarine cable system.

 FIG. 2 is a schematic configuration diagram of an optical repeater.

 [Fig. 3] Conceptual diagram of the power feeding method of the optical submarine cable system, (a) is a normal power feeding state, (b) is a state where a cable ground fault has occurred, and (c) is a power feeding device feeding power. The voltage is adjusted.

 [Fig. 4] The power feeding device is in a state where the power feeding voltage cannot be adjusted.

 FIG. 5 is a schematic configuration diagram of an optical repeater in an embodiment in which some pump lasers according to the present invention are stopped.

FIG. 6 is a schematic diagram of the configuration of an optical repeater in an embodiment in which some optical amplifiers according to the present invention are stopped. FIG. 7 is a schematic configuration diagram of an optical repeater in an embodiment in which some optical amplifiers according to the present invention are stopped and power feeding resistance is reduced.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 5 is a schematic configuration diagram of the optical repeater according to the first embodiment of the present invention.

The optical repeater 2 according to this embodiment includes an optical amplifier 4 and a power supply circuit 5. Furthermore, the optical amplifier 4 includes an erbium-doped fiber 8 that directly amplifies signal light, two pump lasers 71 and 72 that generate optical amplification by pumping it with pump light, and an LD for driving the pump laser. The drive circuits 61 and 62 and the force are also configured. In addition, the power supply circuit 5 includes resistors 92 and 93 for supplying a DC voltage to the LD drive circuits 61 and 62, a pump laser power saving means 12, and a force. The pump laser power saving means 12 includes a resistor 91 for the relay coil, a relay coil 10, and a relay SW11.

[0026] During normal operation, that is, when the necessary feeding current is supplied, the relay SW11 is connected to the a terminal. For this reason, the LD drive circuit 61 drives the pump laser 71 by a DC voltage generated across the resistor 92, and the LD drive circuit 62 drives the pump laser 72 by a DC voltage generated across the resistor 93, and the optical amplifier. 4 generates an optical amplification effect.

Here, when the power supply current to the optical repeater decreases due to a cable ground failure or the like, the pump laser power saving means 12 operates as follows. First, as the voltage of the resistor 91 decreases, the relay coil 10 operates, and the relay SW11 switches the a terminal force to the b terminal and is connected to the b terminal. As a result, the LD drive circuit 62 is disconnected from the resistor 93, and the power supply to the LD drive circuit 62 is stopped. On the other hand, the LD driving circuit 61 receives a DC voltage generated across the resistor 92 and the resistor 93, and the supply voltage to the LD driving circuit 61 is doubled.

As described above, in the present embodiment, by supplying the voltage of the LD drive circuit 62 to the LD drive circuit 61, even when the power supply current to the optical repeater decreases, the LD drive circuit 61 causes the pump laser to be reduced. 71 can be driven. That is, when the pump laser 71 and the pump laser 72 cannot be driven due to a decrease in the supply voltage, the voltage of the LD drive circuit 62 is supplied to the LD drive circuit 61 to maintain the drive of the pump laser 71. ing. This At this time, the optical amplifier is designed so that the optical output of the optical amplifier is maintained to some extent even if the total input power of the pump laser power is slightly reduced, so that communication is maintained.

 FIG. 6 is a schematic configuration diagram of an optical repeater according to the second embodiment of the present invention.

 The optical repeater 2 according to the present embodiment includes optical amplifiers 41 and 42 and a power supply circuit 5. In addition, the optical amplifiers 41 and 42 are erbium-doped fibers (not shown) that directly amplify signal light, respectively, and two pump lasers 71 and 72 that generate optical amplification by pumping it with pump light. And LD drive circuits 61 and 62 for driving the pump laser. In this embodiment, two pump lasers are driven by one LD drive circuit. The power supply circuit 5 also includes resistors 92 and 93 for supplying a direct current voltage to the LD drive circuits 61 and 62, pump laser power saving means 12, and power. The pump laser power saving means 12 includes a resistor 91 for the relay coil, a relay coil 10, and a relay SW 11, and a force.

 [0031] In a normal state, that is, when a necessary feeding current is supplied, the relay SW11 is connected to the a terminal. For this reason, the LD drive circuit 61 drives the pump laser 71 by a DC voltage generated across the resistor 92, and the LD drive circuit 62 drives the pump laser 72 by a DC voltage generated across the resistor 93, and the optical amplifier. 41 and 42 generate optical amplification.

 [0032] Here, when the power supply current to the optical repeater decreases due to a cable ground fault or the like, the pump laser power saving means 12 operates as follows. First, as the voltage of the resistor 91 decreases, the relay coil 10 operates, and the relay SW11 switches the a terminal force to the b terminal and is connected to the b terminal. As a result, the LD drive circuit 62 is disconnected from the resistor 93, and the power supply to the LD drive circuit 62 is stopped. On the other hand, the LD driving circuit 61 receives a DC voltage generated across the resistor 92 and the resistor 93, and the supply voltage to the LD driving circuit 61 is doubled.

As described above, in the present embodiment, by supplying the voltage of the LD drive circuit 62 to the LD drive circuit 61, even when the power supply current to the optical repeater decreases, the LD drive circuit 61 causes the pump laser to be reduced. 71 can be driven. At this time, since the optical amplifier 42 cannot drive the pump laser 72, the optical amplification function cannot be performed. However, the optical amplifier 41 is The amplifier laser 71 can be driven, and an optical amplification function can be performed. In other words, when the functions of both the optical amplifier 41 and the optical amplifier 42 are stopped due to a decrease in the supply voltage, the power of the optical amplifier 42 is supplied to the optical amplifier 41 to maintain the function of the optical amplifier 41. Yes. As a result, it is possible to maintain communication of the fiber pair on one side.

 FIG. 7 is a schematic configuration diagram of an optical repeater according to the third embodiment of the present invention.

 The optical repeater 2 according to this embodiment includes an optical amplifier 4 and a power supply circuit 5. In addition, the optical amplifier 4 includes an erbium-doped fiber 8 that directly amplifies signal light, two pump lasers 71 and 72 that generate pumping light by pumping it with pump light, and a pump laser. LD drive circuits 61 and 62 for driving, and force are also configured. The power supply circuit 5 is composed of resistors 92 and 93 for supplying power to the LD drive circuits 61 and 62 and pump laser power saving means 12. The pump laser power saving means 12 includes a resistor 91 for a relay coil, a resistor 94 connected in parallel to the resistor 93, a relay coil 10, and a relay SW11.

 [0036] During normal operation, that is, when a necessary feeding current is supplied, the relay SW11 is connected to the a terminal and the c terminal. For this reason, the resistor 94 is also disconnected from the circuit force, the LD drive circuit 61 drives the pump laser 71 by the DC voltage generated across the resistor 92, and the LD drive circuit 62 is pumped by the DC voltage generated across the resistor 93. The laser 72 is driven, and the optical amplifier 4 generates an optical amplification function.

 [0037] Here, when the power supply current to the optical repeater decreases due to a cable ground fault or the like, the pump laser power saving means 12 operates as follows. First, as the voltage of resistor 91 decreases, relay coil 10 operates, and relay SW11 switches the a terminal force to the b terminal, and the c terminal force also switches to the d terminal. Will be connected to. As a result, the LD drive circuit 62 is disconnected from the resistor 93 and the power supply is stopped. On the other hand, the LD drive circuit 61 receives a DC voltage generated across the resistors 92, 93, and 94, and the supply voltage to the LD drive circuit 61 increases.

As described above, in this embodiment, it is possible to maintain the optical output of the optical amplifier and maintain communication by driving the pump laser 71 by the LD driving circuit 61 as in the first embodiment. become. In the case of this embodiment, the relay SW11 is connected to the d terminal. The resistor 94 is connected in parallel to the resistor 93 of the power supply path. Since the resistor 94 and the resistor 93 are connected in parallel, the resistance value of the entire power supply path is reduced. As a result, the current of the entire power supply path is slightly recovered, and the possibility that communication can be maintained is increased as compared with the case of the first embodiment.

 Note that the number of optical amplifiers in the optical repeater, the number of pump lasers in the optical amplifier, and the number of LD drive circuits in this embodiment are merely examples, and the present invention is not limited to this example. For example, a configuration in which four optical amplifiers are provided in the optical repeater or a configuration in which four pump lasers are provided in the optical amplifier is also conceivable.

 In each of the embodiments, the pump laser power saving means is provided inside the power supply circuit. The pump laser power saving means need not be provided inside the power supply circuit. An embodiment in which the pump laser power saving means is provided inside the optical amplifier and an embodiment in which the pump laser power saving means is provided outside the optical amplifier in addition to the power supply circuit are also conceivable.

 [0041] The embodiments described above are merely illustrative of the present invention, and are not intended to be limiting. The present invention can be implemented in various other modifications and changes. . Therefore, the scope of the present invention is defined only by the claims and their equivalents.

Claims

The scope of the claims  [1] A plurality of pump lasers for amplifying signal light transmitted from terrestrial transmission equipment, and a power source for supplying current to the pump lasers using a DC power supply current applied from a station on land Circuit,  Pump laser power saving means for stopping supply of current to some pump lasers in response to a decrease in the feed current;  An optical repeater for an optical submarine cable system.  [2] further comprising a plurality of optical amplifiers,  Each pump laser belongs to one of the optical amplifiers,  2. The optical relay of the optical submarine cable system according to claim 1, wherein the pump laser power saving unit stops supplying current to all pump lasers of some optical amplifiers in response to a decrease in the feeding current. vessel. [3] The power supply circuit further includes a resistor for generating a voltage at both ends for supplying a current to the pump laser,  Each pump laser is connected across the resistor,  3. The optical repeater for an optical submarine cable system according to claim 1 or 2, wherein the pump laser power saving means cuts part of the pump laser in resistance. [4] The optical submarine according to claim 3, wherein the pump laser power saving means further reduces a resistance value of a resistor that generates a voltage at both ends for supplying a current to the pump laser in the power supply circuit. Optical repeater for cable systems. [5] An optical submarine Cape Nore system comprising the optical repeater according to any one of claims 1 to 4.