JP2008541461A - Combined optical repeater for submarine optical transmission systems - Google Patents

Abstract

An optical amplifier device is provided for a submarine optical transmission system. The apparatus includes first and second modules. Each module includes an inner housing having an outer dimension substantially equal to the outer dimension of the inner fiber splice housing of the submarine fiber optic cable fitting. The inner housing includes a pair of opposing end faces each having a retaining element for retaining the inner housing within the outer housing of the submarine fiber optic cable joint. The inner housing also includes sidewalls interconnecting the opposite end faces and extending between the longitudinally opposite end faces. The sidewall includes a plurality of through holes, each receptacle having a receptacle portion having a plurality of through holes that are sized to receive passive optical components used in the optical amplifier.

Description

(Description of related applications)
This application claims the benefit of US Provisional Patent Application No. 60 / 681,063, filed May 13, 2005, named “Articulating Repeater,” which is incorporated herein by reference in its entirety. The

  This application is related to US patent application Ser. No. 10 / 687,547, filed Oct. 16, 2003, entitled “Optical Amplifier Module Housed In A Universal Cable Joint”, which is hereby incorporated by reference in its entirety. Incorporated as a reference.

  This application is also related to US patent application Ser. No. 10 / 715,330, filed Nov. 17, 2003, now US Pat. No. 6,917,465, which is hereby incorporated by reference in its entirety. Is incorporated by reference.

  This application is also related to US patent application Ser. No. 10 / 800,424, filed Mar. 12, 2004, entitled “Thermal Management of an Optical Amplifier Module Housed in a Universal Cable Joint”, which is incorporated herein by reference. The entirety of which is incorporated by reference.

(Field of Invention)
The present invention relates to the field of optical repeaters, and more particularly to an optical repeater used in a submarine optical transmission system.

  In submarine optical transmission systems, optical signals transmitted over fiber optic cables are attenuated over cable lengths that can span thousands of miles. In order to compensate for this signal attenuation, optical repeaters are strategically placed along the length of the cable.

  In a typical optical repeater, a fiber optic cable carrying an optical signal enters the repeater and is coupled through various components such as at least one amplifier and an optical coupler and optical decoupler before exiting the repeater. These optical components are coupled to each other via an optical fiber. The repeater is housed in a sealed structure that protects the repeater from ambient damage. During the placement process, the fiber optic cable is wound on a large drum installed on the ship. As a result, the repeater is wound around the drum along with the cable. Due to the nature of the signal and the increasing amount of information transmitted over the optical fiber, the repeater becomes increasingly larger and the increase in repeater length creates problems when wound around the drum. Drums can be up to 9-12 feet in diameter, but current repeaters can be longer than 5 feet in length, so it is impossible to lay flat or even flat along the drum is there. Huge pressures due to forces on the order of 100,000 pounds are encountered at the connection point between the repeater and the fiber optic cable to which the repeater is attached, especially during cable unwinding and winding. Non-equal loads along the cable can result from severe local bending imposed on the cable at the end of the repeater. This load necessarily results in cable component failure at loads well below the tensile strength of the cable itself.

  To prevent cable breakage during repeater placement, a bend limiter is often provided and the purpose of the bend limiter is to equalize the forces imposed on the cable. In addition, a gimbal can be provided at each longitudinal end of the repeater to which the bend limiting device is attached. The gimbal provides free angular movement in two directions. The bending angle enabled by the gimbal between the repeater and the bend limiting device further reduces the local bending imposed on the fiber optic cable.

  Conventional repeaters of large physical size make their placement difficult and increase their complexity and cost.

(Summary of Invention)
In accordance with the present invention, an optical amplifier device is provided for a submarine optical transmission system. The apparatus includes first and second modules. Each module includes an inner housing having an outer dimension substantially equal to the outer dimension of the inner fiber splice housing of the submarine fiber optic cable fitting. The inner housing includes a pair of opposed end faces each having a retaining element for retaining the inner housing within the outer housing of the submarine fiber optic cable fitting. The inner housing also includes sidewalls interconnecting the opposite end faces and extending between the longitudinally opposite end faces. The sidewall includes a plurality of through holes, each receptacle having a receptacle portion having a plurality of through holes that are sized to receive passive optical components used in the optical amplifier. The module also includes at least one circuit board having at least one voltage drop element for transferring voltage from the conductor to the electronics circuit associated with the optical amplifier from the circuit board. The insulated electrical path provides power received from conductors in at least one fiber optic cable to at least one circuit board. The voltage drop element is in thermal communication with the sidewall. The bend limiter couples the first module to the second module.

  In accordance with one aspect of the present invention, each of the modules includes at least one optical amplifier.

  According to another aspect of the invention, the at least one optical pump source is in thermal contact with one of the end faces.

  In accordance with another aspect of the present invention, each of the end faces includes at least one inwardly extending boss. The optical pump source is on one of the bosses extending inside.

  In accordance with another aspect of the present invention, the first side of the circuit board is on a surface extending through the sidewall. A thermal conduction pad is attached to the first side of the circuit board and provides a thermal conduction path between the voltage drop element and the sidewall.

  In accordance with another aspect of the invention, the voltage drop element is attached to a thermally conductive pad.

  In accordance with one aspect of the present invention, a submarine optical fiber cable coupling includes a pair of cable termination units each holding a terminal portion of the optical fiber to be coupled. Each retaining element is connectable to one of the cable termination units.

  In accordance with another aspect of the invention, each conductor of the fiber optic cable to be coupled is in electrical contact with one of the retaining elements.

  In accordance with another aspect of the present invention, the insulated electrical path includes a power line installed in a circuit board that is in electrical contact with one of the retaining elements.

  In accordance with another aspect of the invention, at least one voltage drop element is provided for transferring a portion of the voltage from the power line to the electronics coupled to the optical amplifier.

  According to another aspect of the invention, the voltage drop element is a zener diode.

  According to another aspect of the present invention, the circuit board includes a pair of circuit boards, and the insulated path further includes at least one electrically conductive pin that electrically connects power lines of the pair of circuit boards.

  In accordance with another aspect of the present invention, the plurality of through holes extend laterally through the receptacle portion of the sidewall in the longitudinal direction.

  In accordance with another aspect of the invention, the inner housing has a generally cylindrical shape. The receptacle portion of the sidewall has a curvature that defines the diameter of the cylindrical shape.

  According to another aspect of the present invention, the submarine optical fiber cable joint is a universal joint for coupling optical cables having various configurations.

  According to another aspect of the present invention, the universal joint includes a pair of cable termination units each holding a terminal portion of the optical cable to be coupled. Each retaining element is connectable to one of the cable termination units.

  In accordance with another aspect of the invention, each of the retaining elements includes a flange in which at least one optical fiber extending from a terminal portion of one of the optical cables extends through the flange and into the internal housing.

  In accordance with another aspect of the invention, the fiber optic storage area includes at least one fiber optic spool around which the optical fiber can be wound.

  In accordance with another aspect of the present invention, the inner housing is formed from a pair of half units, each of the pair of half units including one of the retaining elements.

  In accordance with another aspect of the present invention, the sidewall includes a pair of ribbed members extending longitudinally from the receptacle portion of the sidewall. Each of the ribbed members has a tension rod through hole extending longitudinally and laterally to support a tension rod used by the submarine fiber optic cable joint.

  In accordance with another aspect of the present invention, the outer dimension of the inner housing is less than about 15 cm × 50 cm.

  According to another aspect of the invention, the outer dimension of the inner housing is about 7.5 cm × 15 cm.

(Detailed explanation)
We can achieve a substantially smaller repeater by first reducing the length of the repeater so that the pressure on the repeater is significantly reduced during its placement, thereby reducing the gimbal's length. Recognizing that the need is removed. Removing the gimbal at the same time allows further reduction of the repeater dimensions.

  The inventors further recognize that repeaters of substantially reduced size can be housed in units formed from off-the-shelf components suitable for the undersea environment. In particular, the inventors have recognized that the housings conventionally used to interconnect various submarine fiber optic cables can also be used as ultra-small form factor repeater housings. As discussed below, one such housing, commonly referred to as a Universal Joint, has become the de facto worldwide standard for maintaining submarine cables and has a long history of good placement Have The present invention thus provides a repeater that is easily placed due to its small size and installed in a housing suitable for an economical seabed already well established in the submarine optical communications industry. Further, universal joints can interconnect various fiber optic cables so that repeaters can be used to interface with various cables and systems from various manufacturers.

  To facilitate an understanding of the present invention, an embodiment of a submarine fiber optic cable is described in connection with FIG. Various cable manufacturers use cables having various configurations and dimensions, but most cables use most of the components depicted in FIG. 1 in one form or other. The optical cable 330 includes a single centrally installed gel-filled buffer tube 332 made of a metal such as aluminum or stainless steel. Gel filled buffer tube 332 includes an optical fiber 335. In some cases, the buffer tube 332 is replaced by a centrally located king wire surrounded by an optical fiber embedded in the polymer. Two layers of strand wire serving as a strength member are wound around the buffer tube. One layer includes strand wire 338 and the other layer includes strand wire 339. A copper conductor 340 surrounds the strand wire and serves as both an electrical conductor and a hermetic barrier. An outer jacket 342 formed from polyethylene encapsulates the copper conductor 340 and serves as an insulating layer.

  FIG. 2 shows a simplified schematic diagram of a universal cable joint for coupling fiber optic cables for use in submarine optical telecommunications systems. Such a joint is called a universal cable joint because many different types of submarine optical telecommunication cables can be connected to each other regardless of the manufacturer. The cable fitting includes a common component assembly 10 in which a fiber optic splice is installed. The fiber splice is formed from two fibers each resulting from two cables each terminating in a cable termination unit 12. A protection assembly 15 surrounds the common component assembly 10 and the cable termination unit 12 and protects it from the outside environment.

FIG. 3 shows the Global Marine Systems Limited and the
A specific example of a universal cable joint available from the Universal Joint Consortium is shown, often referred to simply as a universal joint, as described above. 2 and 3, like reference numerals indicate like elements in FIGS. In FIG. 3, the protection assembly 15 depicted in FIG. 2 comprises a stainless steel sleeve 14 surrounding the common component assembly 10 and a polyethylene sleeve 16 molded over the common component assembly 10. The stainless steel sleeve 14 provides resistance to tension, twisting and compression loads, and further provides an electrically conductive path through which power can be transferred from the copper conductor of one cable to the other copper conductor.

  The bonding process strips off the various layers of the cable and reveals a predetermined length of outer jacket, copper conductor, strand wire and fiber package (eg, a buffer containing a fiber or a king wire surrounded by an optical fiber) Start by doing. The strand wire is clamped in a ferrule assembly installed in the cable termination unit 12. The fiber package extends into the common component assembly 10, where the fiber package is held in place by a series of clamps. In the common component assembly 10, individual fibers are separated and spliced to their corresponding fibers from the other cable. The splice is looped with extra fiber and looped and wound into a path formed in the common component assembly 10. The common component assembly 10 is inserted into a stainless steel sleeve 14 and the end cap 13 is screwed into each end of the assembly 10. Two tension rods 17 and 19 extend through the end cap 13 and the common component assembly 10. Tension rods 17 and 19 are designed to hold tension loads installed on the universal joint during the placement process in which the joint is moved from the ship to its submarine environment. Finally, the joint is located in a molten polyethylene injected mold and provides a continuous insulation (ie, polyethylene sleeve 16) on the outer jacket of the cable.

  The inventors have recognized that a cable joint, such as the universal cable joint depicted in FIGS. 2 and 3, can be modified to serve as a repeater housing in which one or more optical amplifiers are installed. FIGS. 4-9 illustrate one embodiment of an optical amplifier module 400 that replaces the common component assembly 10 found in FIGS. The optical amplifier module 400 should have substantially the same dimensions as a common component assembly that is only about 7.5 cm × 15 cm. As mentioned above, this size is much smaller than conventional repeater housings that are often several feet long. The optical amplifier module 400 depicted in the figure may support four erbium doped fiber amplifiers (EDFAs) that are physically classified as dual amplifiers for each of the two fiber pairs. Of course, the present invention encompasses an optical amplifier module that can support any number of EDFAs.

  Each optical amplifier includes an erbium-doped fiber, an optical pump source, an isolator, and a gain flattening filter (GFF). The amplifier is forward pumped with a single stage, cross-coupled pump laser. If one of the two pump lasers fails, the 3 dB coupler allows both coils of the dual amplifier erbium-doped fiber to be pumped. At the output, the isolator protects against backscattered light entering the amplifier. The gain flattening filter is designed to flatten the amplifier gain at the designed input power. An additional light path may be provided, allowing the filtered portion of the backscattered light of either fiber to be coupled back in the opposite direction, allowing COTDR type line monitoring. Of course, the optical amplifier module 400 can support EDFAs having various configurations such as multistage amplifiers, forward pumping and back pumping amplifiers, as well as fiber amplifiers using rare earth elements other than erbium.

  The optical amplifier module 400 is designed to be compatible with the rest of the cable joint, thereby connecting to the cable termination unit 12 and fitting within the stainless steel sleeve 14 in the same manner as the common component assembly 10.

  A side view of the optical amplifier module 400 with the end cap 13 in place is shown in FIG. Module 400 is defined by a generally cylindrical shape structure with flanges 402 (as seen in FIG. 5) located on opposite end surfaces 403. Longitudinal plane 405 extends through optical amplifier module 400, thereby bisecting module 400 into two half units 404 and 404 'that are symmetrical about an axis of rotation perpendicular to longitudinal plane 405. That is, as best seen in FIG. 5, rather than dividing the end face 403 into two parts that are installed in different half units 404, each half unit 404 has an end face 403 on which the respective flange 402 is installed. Including a portion of one of them. FIG. 5 shows a perspective view of one of the units 404. In the embodiment of the invention depicted in FIGS. 4-9, each half unit 404 houses two erbium-doped fiber amplifiers.

  The flange 402 matches the cable termination unit 12 of the universal joint shown in FIG. As seen in the cross-sectional views of FIGS. 7 to 8, the through hole 407 extends from the end surface 403 to the inside, and the tension rod of the universal joint is inserted through the end surface 403. End face 403 also includes a clearance hole 430 for securing universal joint end cap 13 to optical amplifier module 400. The clearance hole 430 is located along a line perpendicular to the line connecting the tension rod through hole 407.

  As shown in FIGS. 4-6, each unit 404 includes a curved sidewall 412 that forms a semi-cylinder that defines a portion of the cylindrical shape structure. The spine member 406 is essential to and touches the curved sidewall 412 and extends longitudinally therefrom. A through hole 407 containing a universal joint tension rod extends through the spine member 406. The ceramic boss 440 is installed at the end of the spine member 406 away from the end flange 403. As shown in FIGS. 5 and 7, the through hole 407 extends through the ceramic boss 440. As discussed below, the ceramic boss 440 prevents current flow from one half unit 404 to the other.

  The circuit board support surface 416 extends along the periphery of the unit 404 in the longitudinal plane 405. Circuit board 426 is attached to support surface 416. When the half units 404 and 404 ′ are assembled, the circuit boards 426 and 426 ′ are mutually connected by a pair of interlocking conductive power pins 423 that provide electrical connectivity between the two circuit boards 426 and 426 ′. Connected. The internal cavity of the unit 404 that is placed between the circuit board support surface 416 and the spine member 406 serves as a fiber optic storage area. The optical fiber spool 420 is installed on the inner surface of the spine member 406 in the optical fiber storage area. As with any surplus fiber, erbium-doped fiber is wound around an optical fiber spool 420. The optical fiber spool 420 has an outer diameter that is large enough to prevent at least bending of the fiber beyond its minimum specific bending radius.

  The curved sidewall 412 is thick enough to support a plurality of through holes 418 extending longitudinally therein. Through-hole 418 serves as a receptacle for the passive components of the optical amplifier. That is, each receptacle 418 may include components such as isolators, gain flattening filters, and couplers.

  Each of the end surfaces 403 includes a pair of pump support bosses 403a (see FIGS. 6 and 7) extending inward and parallel to the circuit board 426. The circuit board 426 has a cutout so that the pump support boss 403a is exposed. A pump source 427 that provides pump energy to each optical amplifier is attached to each pump boss 403a.

(Electrical connectivity)
As mentioned above, the electrical connectivity between the cables in the two cable termination units 12 must be maintained. However, the various components in the optical amplifier module 400 are electrically isolated to allow a small voltage (eg, 5-20v) that must be supplied to the electrical components installed on the circuit board 426. I must.

  Referring again to FIG. 3, the optical amplifier module 400 and the sleeve 14 are surrounded by a polyethylene sleeve 16 that serves as a dielectric. Power is taken from the cable conductors installed in the termination unit 12 and transferred through the conductors installed on the circuit board 426. The circuit board is electrically insulated from the optical amplifier module 400 by the epoxy resin of the circuit board acting as a local dielectric. After the voltage drops for one electrical component of the circuit board, the voltage passes from the circuit board 426 to the circuit board 426 ′ via a pair of fault conductive pins 423, the pair of the pair of conductive pins. Each fault conductive pin includes a pin and socket assembly. Pin 423 allows for movement on any axis that may occur as a result of tension or hydrostatic pressure.

  More particularly, referring now to FIGS. 7 and 8, power is supplied to the electrical components as follows. Since the cable termination unit 12 is powered or electrically active, the end cap 13 is also electrically active. A power conductor extends within each of circuit boards 426 and 426 '. The power conductor receives power directly from the pump support boss 403a. One or more voltage drop elements, such as a Zener diode, are installed on the circuit board 426. A Zener diode that electrically couples the power conductor to other electrical components on the circuit board drops a voltage sufficient to power the electrical component. Electrical connectivity extends along the power conductor and is maintained across the circuit board relative to the other via conductive pins 423. In this way, electrical conductivity is installed from one end cap 13 through the end flange 403 and the pump support boss 403a in contact with the end cap 13 to the circuit board 426 in the pump support boss 403a. It extends through the power conductor, through one of the power pins 423 and through the power conductor installed in the other substrate circuit 426. Finally, electrical conductivity extends to the other end cap 13 via another pump support boss 403a and end flange 403.

  The electrical path is isolated from the optical amplifier module 400 as follows. An electrically insulating pad is placed between the circuit board support surface 416 and the circuit board 426. In this way, the pump support boss 403a is electrically insulated from the circuit board 426 except when passing through the power conductor described above. The ceramic isolator 442 surrounds the bolts that fasten the circuit board 426 to the side walls 412 of each half unit 404. The ceramic isolator 442 prevents electrical discharge from the bolts to the components installed on the circuit board 426. The ceramic boss 440 installed in each half unit 404 electrically insulates the spine member 406 from both the end cap 13 and the end flange 403 where the end cap contacts the spine member to which it is connected.

  FIG. 9 shows how the tension rod 409 extending through the through hole 407 is electrically isolated from the end cap 13. As shown in FIG. 9 for the leftmost end cap 13, a ceramic washer 444 surrounds the head of each tension rod 409. The ceramic washer 444 electrically insulates the end cap 13 from the tension rod 409. Since the seal made by the ceramic washer 444 is not hermetic, copper washers 446 and 448 are also provided to ensure that such a hermetic seal is achieved between the tension rod and the end cap 13. ing. The threaded end of the tension rod 409 terminates at the opposite end cap 13, and the threaded end is not electrically isolated from the end cap 13.

  Since the sleeve 14 contacts the end cap 13, the sleeve 14 is preferably formed from a non-conductive material. For example, the sleeve 14 can be formed from a thermally conductive ceramic. Thermally conductive ceramics are advantageous for strength. However, such ceramics are often nominally electrically conductive and need to be provided with an oxidized surface to serve as a dielectric. The oxide surface finish is preferably polished to facilitate the formation of a hermetic seal.

(Thermal management)
Pump source 427 and zener diodes generate a significant amount of heat that must be dissipated to ensure that the temperatures of the various components do not exceed their operating limits. This is a particularly difficult problem. This is because the pump source 427 and the zener diode can generate several watts of power for a small area. Furthermore, thermal energy must be dissipated while simultaneously achieving electrical isolation of these same components, and the two goals are clearly somewhat incompatible with each other. As described in detail below, many features of the optical amplifier module 400 enhance thermal management so that heat is dissipated properly.

  As described above, the pump source 427 is attached to the pump support boss 403 a of the end flange 403. Heat from the pump source 427 is thereby transferred through the pump support boss 403a to the end flange 403, which has a relatively large mass to serve as an effective heat sink. The end flange 403 similarly conducts heat to the end cap 13 seen in FIG.

  The side wall 412 of the optical amplifier module 400 is made of a heat conducting material such as metal, preferably aluminum. The sidewall 412 has a relatively large surface area and therefore serves as a spreader that dissipates heat across its surface in a uniform manner so that its local and overall temperature rise is kept to a minimum. The zener diode is preferably located as close as possible to the sidewall 412 so that heat generated by the diode can be easily transferred to the sidewall 412.

  For example, as best seen in FIG. 10, in one embodiment of the present invention, the Zener diode 484 is located at the bottom of the circuit board 426 (ie, on the circuit board opposite the side where the pump source 427 is located). side). A copper pad 480 is placed on this bottom surface under each of the ceramic isolators 442 that insulate the bolts 482 that secure the circuit board 426 to the support surface 416. Zener diode 484 is attached to copper pad 480 adjacent to bolt 482. The copper pad 480 serves as one of the electrical contacts to each of the zener diodes 484, and the other is indicated by reference numeral 486. A portion of each copper pad 480 is on the circuit board support surface 416. The copper pad 480 contacts the electrically insulating pad on which the circuit board 426 is located. The electrically insulative pad is a relatively good thermal conductor, which conducts heat generated by the Zener diode 484 from the copper pad 480 to the circuit board support surface 416 of the optical amplifier module 400. Thus, heat flows from the zener diode 484 through the copper pad 480 and the electrically insulating pad into the optical amplifier module 400. Once heat is dissipated on the side walls 412 of the module 400, the heat is transferred directly to the stainless steel sleeve 14 surrounding the module 400.

  The wide distribution of heat over the relatively large surface area of the end cap 13 and tension sleeve 14 allows heat to be effectively transferred to seawater through the surrounding polyethylene sleeve 16 which is not a particularly good heat conductor. is there.

(Linking optical amplifier modules)
As discussed in US Pat. No. 6,870,993, in some situations it may be desirable to use a combination of two or more optical amplifier modules depicted in FIGS. 4-9. That is, two or more optical amplifier modules (each inserted into a respective stainless steel sleeve and connected to a respective cable termination unit to form a repeater housing) can be used along the same cable. As mentioned above, the optical amplifier modules depicted above are configured to support two amplifier pairs, so if more amplifier pairs are needed, they can be placed in additional modules. For example, if two repeater housings are coupled to the same cable, four amplifier pairs can be provided. More generally, a concatenation of N optical amplifier modules may support 2N amplifier pairs.

  The connection of two or more repeater housings can also be used to redistribute amplifier components between the housings in a variety of ways. For example, if two such housings are used, one can be used to support all of all optical components and the other can be used to support electronic components. Thus, the various functional elements of the repeater can be distributed in various housings. When three optical amplifier modules are used, each of the optical components, power converter network and pump controller can be installed in various housings. Of course, the amplifier components can also be distributed between the housings in a wide variety of other permutations.

  FIG. 11 shows two optical amplifier modules 610 coupled to the bend limiter 630. The bend limiter 630 prevents the relative rotation between the two optical amplifier modules 610 from exceeding the maximum bend angle. This likewise prevents the fiber from being damaged. Also shown in FIG. 11 is a sleeve 614 (eg, sleeve 14 of FIG. 3) and an overarmor sleeve in which the optical amplifier module 610 is installed, as well as the cable termination unit 612 (eg, cable termination unit 612 of FIG. 3). 616 (eg, sleeve 16 of FIG. 3). As another advantage, this device reduces the number of bend limiting boots required. Instead of requiring a pair of boots for each individual repeater, the optical amplifier modules 610 are so close to each other that only two boots 640 are required for the entire connection of the repeaters. It is.

  In some cases, it may be desirable to couple the optical amplifier module to two conventional cable joints (eg, the universal joint shown in FIG. 3) in the manner shown in FIG. As shown, repeater housing 710 (where the optical amplifier is located) is installed along the cable between conventional cable fittings 720 to provide an integral unit. That is, repeater housing 710, cable segment, and cable joint 720 are operatively coupled together so that they can all be traversed by an optical signal. Providing such an integrated unit to a customer results in a number of advantages. For example, because the cable is already spliced to the conventional cable fitting 720, the customer does not need to open the repeater housing 710 to splice the repeater housing 710 into the cable, and is therefore relatively brittle as a result of the customer opening the housing. Reduce the possibility of damage to repeater components. Further, as in FIG. 12, when the cable pigtail 730 terminates at the end of a conventional cable joint 720 that is remote from the repeater housing 710, the unitary unit is mechanical, electrical and optical for the cable segment. As a cable segment that can use any splicing and joining technique desirable to achieve a secure connection, the integrated unit is considered effective for the customer.

FIG. 1 shows an example of a submarine optical fiber cable. FIG. 2 shows a simplified schematic diagram of a universal cable joint for coupling fiber optic cables for use in submarine optical telecommunications systems. FIG. 3 shows a specific example of a universal cable joint available from Global Marine Systems Limited and the Universal Joint Consortium. FIG. 4 shows a side view of an optical amplifier module constructed in accordance with the present invention. FIG. 5 shows a perspective view of one of the half units forming the optical amplifier module depicted in FIG. FIG. 6 shows a side view of one of the half units forming the optical amplifier module depicted in FIG. FIG. 7 shows a cross-sectional side view of one of the half units forming the optical amplifier module depicted in FIG. FIG. 8 is a sectional side view of the optical amplifier module shown in FIG. FIG. 9 is an enlarged cross-sectional side view of the portion of the optical amplifier module that interconnects with the end cap. FIG. 10 shows a plan view of the bottom of one of the circuit boards illustrating how the zener diode is attached to facilitate heat transfer. FIG. 11 shows two optical amplifier modules connected to a bend limiter. FIG. 12 shows an embodiment of the present invention in which an optical amplifier module is coupled to two universal cable joints.

Claims (20)

An optical amplifier device for a submarine optical transmission system,
At least a first module and a second module, each of the modules comprising:
An inner housing having an outer dimension substantially equal to the outer dimension of the inner fiber splice housing of the submarine fiber optic cable joint, the inner housing comprising:
A pair of opposing end faces, each end face having a holding element for holding the inner housing within the outer housing of the submarine fiber optic cable joint;
Side walls interconnecting the opposite end faces and extending longitudinally between the opposite end faces, the side walls being a plurality of through holes, each through hole comprising a passive optical component used in an optical amplifier At least a first module and a second module including an inner housing including a sidewall portion including a receptacle portion having a plurality of through holes dimensioned to receive;
An optical amplifier device comprising: a bend limiter that couples the first module to the second module.   The optical amplifier apparatus according to claim 1, wherein each of the modules includes at least one optical amplifier. At least one of the modules is
At least one circuit board, wherein there is at least one voltage drop element on the circuit board for conducting a voltage from an optical fiber cable to an electronic device on the circuit board and coupled to the optical amplifier. A circuit board;
The optical amplifier device according to claim 2, further comprising: an insulated electrical path for supplying power received from a conductor of the fiber optic cable to the at least one circuit board.   The optical amplifier device according to claim 3, wherein the voltage drop element conducts heat with the side wall.   The optical amplifier apparatus of claim 2, further comprising at least one optical pump source in thermal contact with one of the end faces.   6. The optical amplifier module of claim 5, wherein each of the end faces includes at least one inwardly extending boss, and wherein the at least one optical pump source is on one of the inwardly extending bosses.   The first side of the circuit board is on a surface extending through the side wall and further comprises a thermal conduction pad attached to the first side of the circuit board, the voltage drop element and the side wall The optical amplifier module according to claim 3, wherein the optical amplifier module provides a heat conduction path between the two.   The optical amplifier module according to claim 7, wherein the voltage drop element is attached to the thermally conductive pad.   The submarine fiber optic cable coupling includes a pair of cable termination units each holding a terminal portion of a fiber optic cable to be coupled, each of the retaining elements being connectable to one of the cable termination units. The optical amplifier module according to claim 3.   The optical amplifier module of claim 9, wherein the conductor of each of the coupled fiber optic cables is in electrical contact with one of the holding elements.   The optical amplifier module of claim 10, wherein the insulated electrical path includes a power line installed in the circuit board that is in electrical contact with one of the holding elements.   The optical amplifier module according to claim 3, wherein the voltage drop element includes a Zener diode.   The at least one circuit board includes a pair of circuit boards, and the insulated electrical path further includes at least one electrically conductive pin that electrically connects the power supply lines of the pair of circuit boards. The optical amplifier module according to claim 11.   The optical amplifier module according to claim 1, wherein the plurality of through holes extend laterally through the receptacle portion of the longitudinal side wall.   The optical amplifier module of claim 1, wherein the inner housing has a generally cylindrical shape, and the receptacle portion of the sidewall has a curvature defining a diameter of the cylindrical shape.   The optical amplifier module according to claim 1, wherein the submarine optical fiber cable joint is a universal joint for coupling optical cables having various configurations.   Each of the retaining elements includes a flange through which at least one optical fiber extending from the terminal portion of one of the optical cables extends into the inner housing. Item 4. The optical amplifier module according to Item 1.   The optical amplifier module according to claim 1, further comprising an optical fiber storage area installed in the inner housing.   The optical amplifier module of claim 18, wherein the optical fiber storage area includes at least one optical fiber spool about which an optical fiber can be wound.   The optical amplifier module according to claim 1, wherein the inner housing is formed of a pair of half units, each of the pair of half units including one of the holding elements.

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