JP2005257940A - Wdm filter module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a WDM filter module which can perform connector connection with high reliability, has an excellent connection characteristic, and is small-sized. <P>SOLUTION: The WDM filter module is provided with a plug structure and a jack structure which incorporate a ferrule, a WDM filter to which a plurality of inputting/outputting optical fibers stored in the ferrule are connected and which conducts predetermined multiplexing and demultiplexing in accordance with wavelength, and a housing which contains a housing part of the plug structure and the jack structure and a housing part storing the WDM filter and is composed of an integrated member. The inputting/outputting optical fibers have a part which is not mechanically restricted between the ferrule and the WDM filter so that the location of the ferrule is freely changed inside the housing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a WDM filter module, and more particularly to a WDM filter module that can accommodate a plurality of optical transceivers in a wavelength division multiplexing transmission system.

  2. Description of the Related Art Conventionally, a wavelength division multiplex transmission system (hereinafter referred to as a WDM (Wavelength Division Multiplex) system) that multiplexes and transmits a plurality of optical signals having different wavelengths on one optical fiber is known. According to the wavelength division multiplexing transmission method, there is no need to use an active device for switching the transmission path, a predetermined wavelength is assigned to each optical signal, and a passive optical wavelength multiplexer / demultiplexer (WDM filter) is used. Thus, each optical signal to be transmitted can be switched to a predetermined transmission path. In a subscriber optical communication system, an upstream optical signal and a downstream optical signal having different wavelengths are multiplexed, and bidirectional transmission is realized by a single optical fiber.

  A subscriber optical communication system that connects an accommodation station having a node of a backbone communication network and a subscriber terminal such as a home or office with an optical fiber has an extremely large transmission capacity compared to information transmission by metal cable or radio. Have Moreover, even if the accommodating station and the subscriber are separated by 10 km or more, large-capacity transmission can be realized. In such a subscriber optical communication system, an extremely large transmission capacity can be used to provide various broadband services such as a high-speed IP (Internet Protocol) service and a multi-channel video service in the same system. .

  In addition, a PON (Passive Optical Network) system transmits time-division between a plurality of subscriber terminals and a receiving station, and a plurality of subscribers are connected to one optical fiber between the receiving station and a branching device. Contained. In the PON system, the transmission capacity allocated to each subscriber terminal is limited. Therefore, in order to further increase the capacity, the introduction of a WDM-PON system that multiplexes and transmits a plurality of optical signals having different wavelengths is being considered. ing.

  An optical transceiver module and a WDM filter module are mounted on an optical transceiver device of a subscriber terminal. A WDM filter module has a plug and jack structure that is detachable for connector connection between an optical transceiver module and a transmission optical fiber, and combines and demultiplexes predetermined signal light according to the wavelength of the optical signal It has a function.

FIG. 1 shows a configuration of a WDM transmission system to which a conventional optical transmission / reception apparatus that performs bidirectional transmission is applied. Each of the n subscriber terminals is provided with optical transmission / reception apparatuses 10-1 to 10-n, and input / outputs thereof are connected to the WDM filter module 1 through optical fibers 12-1 to 12-n. The WDM filter module 1 is connected to the accommodation station by a single optical fiber 13. Optical transceiver 10-1, the wavelength lambda ₁ to the optical signal in the upstream direction (accommodation station side from the subscriber side), are allocated to the wavelength lambda ₂ to the optical signal in the downstream direction (subscriber side from the central office side) . Similarly, wavelengths λ ₃ and λ ₄ are assigned to the optical transceiver 10-2.

Optical transceiver modules 11-1 to 11-n are mounted on the optical transceivers 10-1 to 10-n, respectively, and convert between electrical signals and optical signals. Since the optical transceiver 10-1 performs bi-directional transmission using one (one core) optical fiber, the optical transceiver module 11-1 includes an optical connector to which one optical fiber 12-1 is connected, A WDM filter 14 that multiplexes and demultiplexes optical signals having wavelengths λ ₁ and λ ₂ is incorporated. The optical transmitter (LD) 15 and the optical receiver (PD) 16 are each connected to the WDM filter 14.

The optical transceiver 10-2 performs bidirectional transmission of upstream and downstream optical signals using two (two-core) optical fibers. The optical transceiver module 11-2 has two optical connectors to which two optical fibers 12-2a and 12-2b are connected, and is responsible for transmission and reception of optical signals of wavelengths λ ₃ and λ ₄ , respectively.

Optical signals of wavelengths λ ₂ , λ ₄ ,..., Λ _2n transmitted from the accommodation station side to the subscriber side are demultiplexed by the WDM filter module 1 and transmitted to the optical transceivers 10-1 to 10-n, respectively. . On the other hand, optical signals of wavelengths λ ₁ , λ ₃ ,..., Λ _2n−1 transmitted from the optical transceivers 10-1 to 10 -n are multiplexed by the WDM filter module 1, multiplexed in the optical fiber 13 and accommodated. It is transmitted to the station side. The optical transceivers 10-1 to 10-n correspond to devices such as so-called transponders, ONUs (Optical Network Units), and media converters.

  When such a WDM transmission system is used commercially, the final number of terminals on the subscriber side is not necessarily determined when the system is first installed. In general, terminals, that is, optical transceivers 10-1 to 10-n are additionally installed according to the demand of subscribers. Therefore, at the initial stage of installing the system, it is necessary to install the WDM filter module 1 having a multiplexing / demultiplexing function corresponding to the number of wavelengths in consideration of the final number of terminals. However, if the number of terminals actually used is less than the initial expectation, an excessive investment will occur in the WDM filter module 1 as a result.

  Moreover, the optical fiber cable 12 which connects the WDM filter module 1 and the optical transmission / reception apparatuses 10-1 to 10-n is necessary, and the wiring configuration becomes complicated. And there is a problem that the space for installing the WDM filter module 1 is large and the installation cost becomes high. Furthermore, there is a problem that the number of optical fiber connection points for connecting the WDM filter module 1 and the optical transceivers 10-1 to 10-n increases, and accordingly, loss of optical signal power occurs.

  Therefore, a WDM transmission system with a small installation space, easy optical fiber wiring configuration, easy expansion of the system configuration as the number of subscriber-side terminals increases, and suppression of excessive capital investment (For example, Japanese Patent Application No. 2003-312021 by the present inventor). FIG. 2 shows a configuration of a WDM transmission system to which a conventional optical transmission / reception apparatus that performs bidirectional transmission using a single optical fiber is applied. Each of the n subscriber terminals is provided with optical transmission / reception devices 20-1 to 20-n and mounted with optical transceiver modules 21-1 to 21-n, respectively, for converting between electrical signals and optical signals. Do.

Since the optical transceiver 20-1 performs bidirectional transmission using one (one core) optical fiber, the optical transceiver module 21-1 includes one optical connector jack 31b and wavelengths λ ₁ and λ _2. And a WDM filter 25 for multiplexing and demultiplexing the optical signal. The optical transmitter (LD) 26 and the optical receiver (PD) 27 are each connected to the WDM filter 25. The optical transceiver 20-2 performs bidirectional transmission of upstream and downstream optical signals using two (two cores) optical fibers. The optical transceiver module 21-2 has two optical connector jacks, which are responsible for transmitting and receiving optical signals of wavelengths λ ₃ and λ ₄ , respectively.

Optical signals of different wavelengths λ ₁ , λ ₂ ,..., Λ _2n transmitted / received between the accommodating station side and the optical transceivers 20-1 to 20-n are one optical fiber 22-1 to 22-n. Multiplexed and transmitted in both directions. The optical transceivers 20-1 to 20-n are connected to the optical connectors of the mounted optical transceiver modules 21-1 to 21-n in cascade through the WDM filter modules 24-1 to 24-n that are directly connected. Has been.

The WDM filter modules 24-1 to 24-n have a function of allowing only optical signals having wavelengths assigned to the connected optical transceiver modules 21-1 to 21-n to pass therethrough. Specifically, the WDM filter module 24-1 will be described. The WDM filter module 24-1 transmits an optical signal having a wavelength λ ₂ among optical signals having wavelengths λ ₂ , λ ₄ ,..., Λ _2n transmitted from the accommodation station side and input to the common port (jack 32b). Output to module 21-1. Optical signals of other wavelengths are output from the input / output port (jack 33b).

Further, the optical signal of the upstream wavelength λ ₁ output from the optical transceiver module 21-1 is input (plug 31 a), and is output from the common port to the optical fiber 22-1. Further, optical signals of wavelengths λ ₃ , λ ₅ ,..., Λ _2n−1 output from the other optical transceivers 20-2 to 20-n are input from the input / output ports and directly from the common port to the optical fiber 22- Output to 1.

In this way, the optical signal of wavelength λ _2i transmitted from the accommodation station side and received by the optical transceiver i is installed on the upstream side by the multiplexing / demultiplexing function of the WDM filter modules 24-1 to 24-n. The WDM filter modules 24-1 to 24-i-1 are sequentially passed through and transmitted to the optical transceiver 21-i in the WDM filter module 24-i. On the other hand, the optical signal of wavelength λ _2i-1 transmitted from the optical transceiver 21-i sequentially passes through the WDM filter modules 24-1 to 24-i-1 installed on the upstream side, and the optical fiber 12-1 Is transmitted to. Conventionally, a two-fiber type optical transceiver such as the optical transceiver module 21-2 is used for two-fiber bidirectional transmission, but according to this configuration, it can be applied to one-fiber bidirectional transmission.

  The WDM filter modules 24-1 to 24-n are connected (removably) to optical transceiver modules 21-1 to 21-n having jacks in their interfaces, while the optical fibers 22-1 to 22-n are optically connected. Connector plugs are also connected to the WDM filter modules 24-1 to 24-n. In FIG. 2, for the sake of easy understanding, the WDM filter modules 24-1 and 24-2 are shown in a disconnected state. The jacks and plugs of the optical transceiver modules 21-1 to 21-n, the WDM filter modules 24-1 to 24-n, and the optical fibers 22-1 to 22-n are interchangeable, and the optical fiber 22-1. The plugs ˜22-n can also be connected to the optical transceiver modules 21-1 to 21-n.

  According to this configuration, when a terminal is added to implement a new service, the optical transceiver 20-n + 1 is newly installed. At this time, the WDM filter 24-n may be connected to the optical transceiver 20-n, and the input / output port of the WDM filter 24-n and the optical transceiver 20-n + 1 may be connected by an optical fiber. Here, if the WDM filter 24-n is connected to the optical transceiver module 20-n in advance, the service interruption in the optical transceiver 20-n due to the additional work is eliminated.

  As described above, with this configuration, there is no need to interrupt an existing service performed using the optical transceiver in the operation for adding a subscriber terminal. Furthermore, this operation is simple and easy to wire. Therefore, a new service can be easily added using an existing system. Moreover, since equipment can be added according to the increase in subscriber terminals, excessive capital investment can be reduced.

  In the WDM transmission system described above, a single-fiber bidirectional transmission optical transceiver module and a two-fiber bidirectional transmission optical transceiver module can be connected. In addition, the optical transceiver requires a small WDM filter module to which an optical connector plug can be connected. The form of the WDM filter module in such a usage form is sometimes referred to as a “pluggable type”, but is hereinafter simply referred to as a WDM filter module.

  As a specific structure or configuration of the WDM filter module, for example, the structure of a fixed attenuator described in Non-Patent Document 1 can be applied. FIG. 3 shows a configuration of a conventional WDM filter module for two-core bidirectional transmission. The WDM filter module 24-2 includes a WDM filter 28 that multiplexes and demultiplexes the optical signal according to the wavelength inside the housing 36-2. The two ports fitted and connected to the jack of the optical connector of the optical transceiver module are respectively composed of plugs 34a and 35a. On the other hand, the two ports fitted and connected to the plug of the optical fiber on the accommodation station side are composed of jacks 32b and 33b, respectively. The plugs 34a and 35a and the jacks 32b and 33b respectively have ferrules 37a to 37d in which optical fibers are accommodated on the central axis.

  FIG. 4 shows a configuration of a first example of a conventional WDM filter. The inside of the WDM filter 28a is constituted by an optical circuit composed of an optical waveguide or the like formed on the substrate 38. The ferrules 37a to 37d are fixed to the end of the substrate 38 including the end of the optical waveguide while being positioned with high accuracy with respect to the optical waveguide.

  FIG. 5 shows a configuration of a second example of a conventional WDM filter. The WDM filter 28 b has an optical circuit in which a dielectric multilayer interference filter 39 and a mirror 40 are arranged inside a housing 42. The ferrules 37a to 37d are fixed to the housing 42, and collimating lenses 41a to 41d are attached to the end faces of the ferrules 37a to 37d including the end face of the optical fiber. Light emitted from the end surfaces of the ferrules 37a to 37d is converted into a collimated light beam by the collimating lenses 41a to 41d. The converted light beam is reflected or transmitted by the dielectric multilayer interference filter 39 inclined at 45 degrees with respect to the optical axis, reflected by the mirror 40, and incident on the other ferrules 37a to 37d.

  FIG. 6 shows a configuration of a conventional WDM filter module for single-fiber bidirectional transmission. The configuration is the same as that of the WDM filter module shown in FIG. 3 except that one port is fitted and connected to the jack of the optical transceiver module.

Nagase et al., "SC-type optical fixed attenuator using metal-doped optical fiber", IEICE Technical Report, vol.95, No.3 (EMD95 1-5) pp.19-24, 1995

  Generally, two jacks of an optical transceiver module for two-core transmission each have a built-in ferrule. These two ferrules are fixed with respect to the main body of the optical transceiver module, and the relative position and the axial direction cannot be changed in the axial direction and the direction perpendicular thereto. On the other hand, for the WDM filter module, since the ferrules 37c and 37d are fixed to the WDM filter 28, it is difficult to change the relative position and the axial direction. Although the two ferrules 37c and 37d of the optical transceiver module or the two ferrules 37c and 37d of the WDM filter module have a specified relative distance, they actually have some errors.

  Therefore, when the WDM filter module cannot be fitted and connected to the optical transceiver module, there are cases where normal connection characteristics such as connection loss and return loss cannot be secured even if the WDM filter module can be connected. In order to ensure that the ferrule can be normally connected, the ferrule can hardly be bent at a length of several millimeters, so that the dimensional tolerance needs to be very small, which is not practical. It is not realistic to distort the joint portion between the WDM filter 28 and the ferrules 37c and 37d.

  A general optical connector realizes a PC (physical contact) that presses the ferrule in the axial direction to closely contact the ferrule end faces to be joined. The PC suppresses transmission light reflection at the end face of the optical fiber. The relative positions of the end surfaces of the two ferrules in the optical transceiver module or the end surfaces of the two ferrules 37c and 37d of the WDM filter module are also slightly different in the axial direction. Therefore, when the WDM filter module is connected to the optical transceiver module, there is a high possibility that only one of the two end faces is realized by the PC.

  In order to realize the PC between the ferrules 37c and 37d and the ferrule end faces in the optical transceiver module, the axial pressing force is applied by a spring built in an optical fiber plug connected to the jacks 32b and 33b of the WDM filter module. can get. This eliminates the need to incorporate a spring in the WDM filter module.

  However, this pressing force always acts on the WDM filter 28 and the joint portion between the WDM filter 28 and the ferrules 37c and 37d when the WDM filter module is used. As a result, if the relative positions of the ferrules 37c and 37d with respect to the WDM filter 28 fluctuate even if they are about several μm, the optical axis shifts and a large loss of optical signal power occurs. For example, even if the adhesive strength between the WDM filter 28 and the ferrules 37c and 37d is increased and a predetermined filter operation is secured initially, there is a problem that long-term reliability cannot be secured.

  The WDM filter module shown in FIG. 5 does not cause a problem regarding the positional error between the ferrules, but as described above, a problem arises regarding a decrease in reliability due to the pressing force for realizing the PC.

  When the WDM filter module is connected to the optical transceiver module and the optical fiber plug is connected to the WDM filter module, an external force from the optical fiber, particularly a tensile force, acts on the WDM filter module, and the connection portion between the optical transceiver module In some cases, a bending moment is applied. This causes a malfunction of the optical transceiver module. This bending moment increases as the total length of the WDM filter module increases.

  When the interface of the optical transceiver module is a MU connector jack, the ferrule is relatively thin, the split sleeve is thin, and the strength at the connection point is relatively low. Required.

  As described above, the relative position of the two ferrules on the plug side of the WDM filter module used in the state connected to the optical transceiver module can be changed. It is desirable that the position error between the two ferrules is absorbed. Further, it is desirable that the pressing force for realizing the PC is suppressed from acting on the WDM filter. Furthermore, it is required to sufficiently shorten the overall length of the WDM filter module to reduce the bending moment.

  The present invention has been made in view of such problems, and its object is to have compatibility with existing optical transceiver modules and optical connectors, and to perform connector connection with high reliability. It is to provide a small WDM filter module having good connection characteristics.

  In order to achieve the above object, the present invention is characterized in that one or a plurality of plug structures coupled with an optical connector jack and incorporating a cylindrical ferrule, and an optical connector plug are provided. 1 or a plurality of jack structures containing a cylindrical ferrule and a plurality of input / output optical fibers accommodated in the ferrule are connected to each other and input via the plurality of input / output optical fibers. A WDM filter that performs predetermined multiplexing / demultiplexing on the optical signal according to a wavelength and outputs the result to the plurality of input / output optical fibers, a housing portion of the plug structure and the jack structure, and the WDM filter. A housing that includes a housing portion that is housed, and is configured of an integral member, wherein the input / output optical fiber is disposed inside the housing. Ferrule to the to freely position variation, between said ferrule and said WDM filter, and having a mechanically unconstrained portion.

  According to this configuration, a part of the input / output optical fiber between the ferrule and the WDM filter is not mechanically restricted, and the position of the optical fiber and the degree of bending can be freely changed to some extent. Since the ferrule is also fixed to the housing with a certain clearance (clearance), the ferrule can change the position and the direction of the central axis in all directions (axial direction, lateral direction, longitudinal direction) within the clearance range. it can.

  Therefore, even if there is a certain dimensional tolerance in the distance between the two ferrules in the two jacks of the optical transceiver module for two-fiber bidirectional transmission, the two ferrules of the plug of the WDM filter module are positioned accordingly. Since it can be varied, the optical transceiver module and the WDM filter module can be fitted. Thereby, PC of the end surfaces of a ferrule can be implement | achieved and a connector connection can be performed with high reliability, without impairing a connection characteristic.

  According to a second aspect of the present invention, the ferrule built into one of the plug structures according to the first aspect and the ferrule built into one of the jack structures are opposed to each other. They are integrated so that their optical axes coincide.

  According to this configuration, when the transmission optical fiber and the WDM filter module are connected, the PC between the end faces of the ferrule can be realized by the pressing force of the spring built in the plug of the transmission optical fiber. Further, since the pressing force for obtaining the PC hardly acts on the WDM filter, it is possible to prevent the deterioration of the reliability of the WDM filter and the connection portion between the WDM filter and the optical fiber due to the pressing force.

  According to a third aspect of the present invention, the ferrule built into one of the plug structures according to the second aspect and the ferrule built into one of the jack structures are a third member. It is characterized by being integrated via.

  The invention according to claim 4 is characterized in that the plug structure according to claim 1 has a spring for pressing a built-in ferrule toward the jack side of the optical connector along the optical axis direction.

  According to this configuration, when the WDM filter module is connected to the optical transceiver module, the ferrule is pressed by the spring of the plug, and the PC at the ferrule end face can be realized. Since each ferrule can be handled independently in the manufacturing process, the end face of the plug ferrule and the end face of the jack ferrule can be polished together. Further, it is possible to cope with the case where the outer shape of the ferrule is different. In addition, the plug and jack ferrule axes do not need to be coincident, increasing the degree of freedom in the design of the plug and jack positions.

  According to a fifth aspect of the present invention, in at least one of the jack structures according to the fourth aspect, the optical axis direction of the built-in ferrule is 45 with respect to the optical axis direction of the ferrule built in the plug structure. It has an angle of not less than 90 ° and not more than 90 °.

  The invention according to claim 6 is characterized in that the input / output optical fiber according to any one of claims 1 to 5 is taken out only from one side of the WDM filter.

  According to this configuration, if the position and orientation of the WDM filter are appropriately determined, the space required for the input / output optical fiber wiring can be reduced. This can reduce the width and height of the WDM filter module and reduce the size.

  The invention according to claim 7 is characterized in that the WDM filter according to claim 6 is fixed in contact with the housing portions of the plurality of jack structures.

  The invention according to claim 8 is characterized in that the plug structure and jack structure according to any one of claims 1 to 7 are compatible with an MU type optical connector.

  The invention according to claim 9 is characterized in that the plug structure and the jack structure according to any one of claims 1 to 7 are compatible with an LC type optical connector.

  A tenth aspect of the present invention is characterized in that the WDM filter according to any one of the first to seventh aspects performs multiplexing / demultiplexing using a multilayer interference filter.

  According to an eleventh aspect of the present invention, in the input / output optical fiber according to any one of the first to seventh aspects, an effective relative refractive index difference between the core portion and the clad portion is 0.75% or more, and the clad The outer diameter is 90 μm or less.

  According to this configuration, the allowable value of the bending radius of the optical fiber is small, the space of the optical fiber wiring between the ferrule of the plug and jack and the WDM filter is reduced, and the size (total length, width, height) of the WDM filter module is reduced. ) Can be reduced.

  As described above, according to the present invention, a compact WDM filter having compatibility with existing optical transceiver modules and optical connectors, enabling high-reliability connector connection, good connection characteristics, and the like. Modules can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 7 shows a WDM filter module according to the first embodiment of the present invention. FIG. 7A is a cross-sectional view seen from above, and FIG. 7B is a vertical cross-sectional view seen from the side. The WDM filter module of the first embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. In the WDM filter module, a WDM filter 102 that multiplexes and demultiplexes an optical signal according to the wavelength is mounted inside the housing 101.

  In the WDM filter module, two ports that are fitted and connected to the jack of the optical connector of the optical transceiver module are composed of two plugs 111 and 112. On the other hand, the two ports fitted and connected to the plug of the optical fiber for transmission on the accommodation station side are composed of jacks 121 and 122, respectively. Here, the plug and the jack are portions of a pair of optical connectors, and they are fitted to achieve optical connection. The plugs 111 and 112 are respectively connected to the transmission port and the reception port of the optical transceiver module, and the jacks 121 and 122 are transmission optical fiber plugs toward the accommodation station and transmission light toward the other optical transceiver modules. Each is connected to a fiber plug.

  The housing 101 has a structure in which the plugs 111 and 112 and the jacks 121 and 122 are coupled together. Of course, the housing 101 may be composed of a plurality of members. In other words, parts of the housing 101 are plugs 111 and 112 and jacks 121 and 122, respectively.

  Plugs 111 and 112 and jacks 121 and 122 have ferrules 131 to 134, respectively. The ferrules 131 to 134 have a circular cross section and accommodate one optical fiber in the central axis. Split sleeves 141 and 142 for aligning the inserted ferrules are fitted into the ferrules 133 and 134 of the jacks 121 and 122, respectively. In the jacks 121 and 122, locking pieces 161 a and 161 b for fixing the inserted plug are formed integrally with the housing 101.

With such a configuration, among the optical signals having different wavelengths λ ₂ , λ ₄ ,..., Λ _m input from the jack 121, the optical signal having the wavelength λ ₂ is output from the plug 112. Optical signals of other wavelengths λ ₄ ,..., Λ _m are output from the jack 122. The optical signal having the wavelength λ ₁ input from the plug 111 is output from the jack 121. Furthermore, optical signals of wavelengths λ ₃ , λ ₅ ,..., Λ _m−1 input from the jack 122 are also output from the jack 121.

  Four optical fibers 151 to 154 are used for optical input / output with respect to the WDM filter 102. The four optical fibers 151 to 154 are inserted into the ferrules 131 to 134, respectively, and reach the ferrule end face. Here, the optical fibers 151 to 154 are not mechanically constrained between the optical fiber 151 to 154 and the housing 101 that covers the optical fiber in the region between the WDM filter 102 and the ferrules 131 to 134. Accordingly, the positions of the optical fibers 151 to 154 can be freely changed to some extent.

  In the first embodiment, the ferrule 131 and the ferrule 133, and the ferrule 132 and the ferrule 134 are integrally formed so that the respective optical axes facing each other coincide with each other, and are formed from one ferrule member. The predetermined portion near the center in the longitudinal direction of the ferrule member 135 has a structure in which the upper half is removed, and the optical fibers 151 to 154 can be inserted into the ferrules 131 to 134. Hereinafter, a member in which the ferrule 131 and the ferrule 133 are integrated is referred to as a ferrule member 135, and a member in which the ferrule 132 and the ferrule 134 are integrated is referred to as a ferrule member 136.

  The end faces of the ferrules 131 to 134 including the end faces of the optical fibers 151 to 154 are processed into a convex spherical smooth surface by polishing to realize PC. The WDM filter 102 is fixed to the housing 101, but the ferrules 131 to 134 are not directly fixed to the housing 101. The ferrules 131 to 134 can freely move in an axial direction or a direction perpendicular thereto within a range of clearance with the housing 101. From another viewpoint, the ferrules 131 to 134 can change the relative position with respect to the WDM filter 102. Furthermore, the relative position of the ferrule member 135 and the ferrule member 136 can also be changed.

  Thus, when the plugs 111 and 112 of the WDM filter module are fitted and connected to the optical transceiver module, the interval between the ferrule member 135 and the ferrule member 136 is made to coincide with the interval between the two ferrules in the optical transceiver module. Can do. In other words, the error between the two ferrules in the optical transceiver module can be absorbed, and the connection is not hindered.

  Further, when the plugs 111 and 112 of the WDM filter module are connected to the optical transceiver module and the plug of the optical fiber for transmission is connected to the jacks 121 and 122, the pressing force by the spring built in the plug is the end face of the ferrule 133. Then, it acts on the end face of the ferrule 131 via the ferrule member 135. Thereby, the PC is realized on the end faces of the ferrules 131 and 133. The same applies to the ferrules 132 and 134.

  As described above, in order to realize the PCs on the end faces of the ferrules 131 to 134, a pressing force is used from the plug of the transmission optical fiber, so that the WDM filter module does not need to include a spring and has a simple structure. become. Further, since the pressing force acting on the ferrules 131 to 134 hardly acts on the WDM filter 102, the reliability of the WDM filter 102 due to the pressing force does not decrease.

  As the WDM filter 102, a multilayer interference filter, a diffraction grating (grating), a distributed grating (eg, fiber grating), or a flat substrate optical waveguide circuit (control of the phase of light by the optical waveguide) can be applied. However, when a multilayer interference filter is used in particular, the size of the WDM filter 102 can be reduced.

  Further, the arrangement and configuration of the WDM filter 102 and the optical fibers 151 to 154 according to the first embodiment are such that when the WDM filter 102 is sufficiently short in the longitudinal direction, the height and width of the WDM filter module are reduced. It is valid.

(Second Embodiment)
FIG. 8 shows a WDM filter module according to the second embodiment of the present invention. The WDM filter module of the second embodiment corresponds to an optical transceiver module for one-fiber bidirectional transmission having one transmission / reception port. In the WDM filter module, a WDM filter 202 that multiplexes and demultiplexes an optical signal according to the wavelength is mounted inside the housing 201.

  In the WDM filter module, a port that is fitted and connected to the jack of the optical connector of the optical transceiver module is composed of one plug 211. On the other hand, the two ports fitted and connected to the plug of the optical fiber on the accommodation station side are composed of jacks 221 and 222, respectively. The WDM filter module of the second embodiment has a structure in which the plug 112 is removed from the WDM filter module of the first embodiment.

  Three optical fibers 251, 253, and 254 are used for optical input / output with respect to the WDM filter 202. The three optical fibers 251, 253, 254 are inserted into the ferrules 231, 233, 234, respectively, and reach the ferrule end face. Here, in the region between the WDM filter 202 and the ferrules 231, 233, and 234, the optical fibers 251, 253, and 254 are not mechanically constrained between the housing 201 that covers them.

  The ferrule 231 and the ferrule 233 are formed of a single ferrule member 235 so that the respective optical axes facing each other are integrated. When the transmission optical fiber plug is connected to the jack 221, the pressing force by the spring built in the plug realizes PC at the end faces of the ferrules 231 and 233. The ferrule 242 is restricted by the housing 201 from moving in the axial direction from the jack 222 toward the WDM filter 202. Therefore, when a plug is connected to the jack 222, a reaction against the pressing force from the plug is generated, and PC at the end face of the ferrule 234 is realized. On the other hand, the WDM filter 202 and the ferrules 231, 233, and 234 can move relative to each other, and the above-described pressing force hardly acts on the WDM filter 202.

With such a configuration, among the optical signals having different wavelengths λ ₂ , λ ₄ ,..., Λ _m input from the jack 221, an optical signal having a wavelength λ ₂ is output from the plug 211. Optical signals of other wavelengths λ ₄ ,..., Λ _m are output from the jack 222. The optical signal having the wavelength λ ₁ input from the plug 211 is output from the jack 221. Furthermore, optical signals of wavelengths λ ₃ , λ ₅ ,..., Λ _m−1 input from the jack 222 are also output from the jack 221.

(Third embodiment)
FIG. 9 shows a WDM filter module according to a third embodiment of the present invention. In the WDM filter module of the third embodiment, the jack 222 and the ferrule 234 of the WDM filter module of the second embodiment are removed, and the optical fiber 254 is extended to be an input / output optical fiber. The optical fiber 353 is fixed at the rear end of the WDM filter module so that an external force does not act on the optical fiber 353. A boot 361 is provided at a portion of the optical fiber 353 drawn from the WDM filter module to prevent breakage.

  The filter operation is the same as in the second embodiment. By adopting the structure of the third embodiment in accordance with the form of the external structure for inputting and outputting optical signals, the volume can be reduced by the amount of the jack 222 as compared with the second embodiment.

(Fourth embodiment)
FIG. 10 shows a WDM filter module according to the fourth embodiment of the present invention. FIG. 10A is a cross-sectional view seen from above, and FIG. 10B is a vertical cross-sectional view seen from the side. The WDM filter module of the fourth embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. In the WDM filter module, a WDM filter 402 that combines and demultiplexes an optical signal according to a wavelength is fixed to a housing 401. The fixed position of the WDM filter 402 may be the lower or upper portion of the WDM filter module, that is, the side surface in the vertical direction, in addition to the side surface in the horizontal direction.

  In the WDM filter module, two ports that are fitted and connected to the jack of the optical connector of the optical transceiver module include two plugs 411 and 412. On the other hand, the two ports fitted and connected to the transmission optical fiber plug on the accommodation station side are composed of jacks 421 and 422, respectively. The housing 401 has a structure in which plugs 411 and 412 and jacks 421 and 422 are coupled together.

  Four optical fibers 451 to 454 are used for optical input / output with respect to the WDM filter 402. The four optical fibers 451 to 454 are “taken out” only from one side of the WDM filter 402. Here, a more specific meaning of “taken out” means that these optical fibers 451 to 454 are attached to the WDM filter 402 main body, or are shared with the optical fibers in the WDM filter 402, so that the WDM filter 402 It is pulled out from the main body. The WDM filter 402 is fixed to the side surface of the housing 401 in the lateral direction.

  Further, the direction of the WDM filter 402 is a direction in which the direction in which the optical fibers 451 to 454 are drawn from the WDM filter 402 is the horizontal direction. Here, the lateral direction is a direction perpendicular to the ferrule 431 and connecting the ferrule 431 and the ferrule 433. Hereinafter, the central axis direction of the ferrule 431 will be referred to as the axial direction (longitudinal direction), and the lateral direction and the direction perpendicular to the axial direction will be referred to as the vertical direction (vertical direction). In addition, the maximum dimensions in the axial direction, the horizontal direction, and the vertical direction of the WDM filter module are referred to as a total length, a width, and a height, respectively.

FIG. 11 shows a more detailed structure of the WDM filter 402. As the WDM filter 402, a multilayer interference filter is applied. The optical fibers 451 to 454 are fixed in parallel and in parallel to a member 471 at one end of the WDM filter 402, and collimating lenses 472a to 472d are attached to the respective tips. Optical signals having different wavelengths λ ₁ , λ ₃ ,... Λ _m are transmitted or reflected through the multilayer interference filters 473a and 473b and the mirrors 474a and 474b, and are multiplexed / demultiplexed.

  In the fourth embodiment, the ferrule 431 and the ferrule 433 are integrated by a joint 435 that is a third member so that the respective optical axes facing each other coincide. Similarly, the ferrule 432 and the ferrule 434 are integrated by a joint 436. The ferrules 431 to 434 are not directly fixed to the housing 401, and can freely move in the axial direction or a direction perpendicular thereto within a range of clearance with the housing 401.

  Input / output optical fibers 451 to 454 attached to the WDM filter 402 are inserted into the ferrules 431 to 434, respectively, and fixed with an adhesive or the like. The end surfaces of the ferrules 431 to 434 including the end surfaces of the optical fibers 451 to 454 are processed into a convex spherical smooth surface by polishing to realize PC. In the region between the WDM filter 402 and the ferrules 431 to 434, the optical fibers 451 to 454 convert the axial direction into an arc shape by 90 °. In this region, the optical fibers 451 to 454 are not mechanically constrained by the distance from the housing 401, and the position and the degree of bending can be freely changed to some extent.

  With this configuration, when the plugs 411 and 412 of the WDM filter module are connected to the optical transceiver module and the plug of the transmission optical fiber is connected to the jacks 421 and 422, the pressing force by the spring built in the plug is The ferrule 433 acts on the end surface of the ferrule 431 through the joint 435 from the end surface. Thereby, PC is realized at the end faces of the ferrules 431 and 433. On the other hand, since the pressing force acting on the ferrules 431 to 434 hardly acts on the WDM filter 402, the reliability of the WDM filter 402 due to the pressing force does not decrease.

  Compared with the first embodiment, the WDM filter module of the fourth embodiment has an error in the distance between two ferrules in the optical transceiver module to be connected, a difference in the axial position of the end faces, ferrules 431 and 433. Even if there is a large error such as a difference in the total length of the ferrules 432 and 434, the connection can be made without any trouble. In other words, the tolerance of these errors can be increased. This is because the change in the bending radius of the optical fibers 451 to 454 is small with respect to the movement amount of the ferrules 431, 433 and the ferrules 432, 434 in the axial direction, the horizontal direction, or the vertical direction, so that it does not fall below the allowable bending radius. It is because it can be made.

  In the arrangement of the WDM filter 402 and the wiring form of the optical fibers 451 to 454, the total length of the ferrules 431 and 433 and the ferrules 432 and 434 is not affected by the maximum dimension of the WDM filter 402. Therefore, although the width of the WDM filter module is slightly increased, the overall length can be shortened. On the other hand, in the WDM filter module of the first embodiment, the total length of the ferrule members 135 and 136 is increased according to the axial dimension of the WDM filter 101 to be mounted. In addition, since the optical fibers 151 to 154 are drawn from the WDM filter 101 in parallel with the axial direction of the ferrule members 135 and 136, the movable amount in the axial direction of the ferrules 131 to 134 cannot be taken sufficiently.

  In the WDM filter module of the first embodiment, the length of the ferrule members 135 and 136 is shortened by disposing the WDM filter 101 at a position somewhat away from the ferrules 131 to 134 and lengthening the optical fibers 151 to 154. be able to. However, the wiring of the optical fibers 151 to 154 requires a certain bending radius, and it is necessary to secure a space for covering with the housing 101 in order to protect the optical fibers 151 to 154. The width and height of the WDM filter module are greatly increased.

  In practical use, when an optical transceiver module, a WDM filter module, and a transmission optical fiber plug are connected, an external force from the transmission optical fiber, particularly a tensile force, acts on the WDM filter module. A bending moment may be applied to the jack portion. This bending moment increases as the total length of the WDM filter module increases. Therefore, by shortening the total length of the WDM filter, the allowable value of the external force that acts on the WDM filter module from the transmission optical fiber can be increased. Further, the possibility that the connection at the jack portion of the optical transceiver module becomes incomplete or the jack portion is damaged due to the external force from the transmission optical fiber can be reduced.

  The total length of the ferrules 431 and 433 and the ferrules 432 and 434 largely depends on the lower limit (allowable value) of the bending radius of the optical fibers 451 to 454. Therefore, in order to shorten the ferrules 431 to 434 and further shorten the total length of the WDM filter module, as will be described in detail later, a small-diameter optical fiber having a large relative refractive index difference between the core and the clad is used.

(Fifth embodiment)
FIG. 12 shows a WDM filter module according to the fifth embodiment of the present invention. The WDM filter module of the fifth embodiment corresponds to an optical transceiver module for one-fiber bidirectional transmission having one transmission / reception port. In the WDM filter module, a WDM filter 502 that combines and demultiplexes an optical signal according to a wavelength is fixed to a housing 501. As a fixed position of the WDM filter 502, in addition to the side surface in the horizontal direction, the lower or upper portion of the WDM filter module, that is, the side surface in the vertical direction can be used.

  In the WDM filter module, a port that is fitted and connected to the jack of the optical connector of the optical transceiver module includes one plug 511. On the other hand, the two ports fitted and connected to the plug of the optical fiber on the accommodation station side are composed of jacks 521 and 522, respectively. The WDM filter module of the fifth embodiment has a structure in which the plug 412 is removed from the WDM filter module of the fourth embodiment.

  The ferrule 531 and the ferrule 533 are integrated so that the respective optical axes facing each other coincide with each other, and are formed from one ferrule member. When the transmission optical fiber plug is connected to the jack 521, the pressing force by the spring built in the plug realizes PC at the end faces of the ferrules 531 and 533. The ferrule 542 is restricted by the housing 501 from moving in the axial direction from the jack 522 toward the inside of the module. Therefore, when a plug is connected to the jack 522, a reaction against the pressing force from the plug is generated, and PC at the end face of the ferrule 534 is realized.

(Sixth embodiment)
FIG. 13 shows a WDM filter module according to the sixth embodiment of the present invention. FIG. 13A is a cross-sectional view seen from above, and FIG. 13B is a vertical cross-sectional view seen from the side. The WDM filter module of the sixth embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. In the WDM filter module, a WDM filter 602 that combines and demultiplexes an optical signal according to a wavelength is fixed to a housing 601. As a fixed position of the WDM filter 602, in addition to the side surface in the horizontal direction, the lower portion or the upper portion of the WDM filter module, that is, the side surface in the vertical direction can be used.

  For example, when used in an optical transmission / reception apparatus, a height restriction is generally more strongly required, and therefore a WDM filter module in which a WDM filter 602 is disposed on a lateral side surface is used. When the optical transceiver module is disposed in the interface portion of the optical transceiver, and the WDM filter module is attached to the interface of the optical transceiver, the height limit of the WDM filter module is relatively small.

  Four optical fibers 651 to 654 are used for optical input / output with respect to the WDM filter 602. The four optical fibers 651 to 654 are taken out only from one side of the WDM filter 602. The direction in which the optical fibers 651 to 654 are drawn is an axial direction from the jack 621 toward the plug 611. However, the specific position of the WDM filter 602 is determined in consideration of the allowable value of the bending radius of the optical fibers 651 to 654.

  In the sixth embodiment, the ferrule 631 and the ferrule 633 are integrated by a joint 635 so that the respective optical axes facing each other coincide. Similarly, the ferrule 632 and the ferrule 634 are integrated by a joint 636. The ferrules 631 to 634 are not directly fixed to the housing 601 and can freely move in the axial direction or a direction perpendicular thereto within a range of clearance with the housing 601.

  The total lengths of the ferrules 631 and 633 and the ferrules 632 and 634 largely depend on the allowable value of the bending radius of the optical fibers 651 to 654, but can be as short as the WDM filter module of the fourth embodiment. If the bending radius of the optical fibers 651 to 654 can be reduced, the WDM filter 602 can be disposed at a position close to the ferrules 631 to 634 in the lateral direction. Further, the space required for the wiring of the optical fibers 651 to 654 is reduced, and the width of the WDM filter module can be reduced. Furthermore, the overall lengths of the ferrules 631 and 633 and the ferrules 632 and 634 can be shortened.

FIG. 14 shows a more detailed structure of the WDM filter 602. The WDM filter 602 includes an optical waveguide formed on a flat substrate 671 and multilayer interference filters 673a and 673b. The multilayer interference filters 673a and 673b and the mirror 674 are inserted into the tolerance portion of the optical waveguide. Optical signals having different wavelengths λ ₁ , λ ₂ ,... Λ _m input from the optical fibers 651 to 654 to the optical waveguide are reflected or transmitted by two multilayer interference filters 673a and 673b, and are multiplexed and demultiplexed. The The optical signal that has passed through the multilayer interference filters 673a and 673b is reflected by the mirror 674, and the optical waveguide is folded back. Compared with the case where the optical waveguide is bent, the area of the substrate can be reduced.

  The optical fibers 651 to 654 are fixed to one side of the end face of the flat substrate 671 including the end face of the optical waveguide. Thus, the WDM filter in which the optical waveguide and the multilayer interference filter are combined is small and does not require a collimating lens. In addition, since a technique for attaching an optical fiber to an optical waveguide substrate has been established, it can be mass-produced at a low cost.

  In the sixth embodiment, the ferrule 631 and the ferrule 633 are integrated by a joint 635 so that the respective optical axes facing each other coincide. Similarly, the ferrule 632 and the ferrule 634 are integrated by a joint 636. The ferrules 631 to 634 are not directly fixed to the housing 601 and can freely move in the axial direction or a direction perpendicular thereto within a range of clearance with the housing 601. This facilitates the insertion of the optical fibers 651-654 into the ferrules 631-634.

  Further, not only the end faces of the four ferrules 631 to 634 can be polished together, but also the handling of the WDM filter 602 and the optical fibers 651 to 654 during polishing becomes easy. Moreover, it is easy to mechanically expand the hole diameter with respect to the insertion port of the optical fibers 651 to 654 of the ferrules 631 to 634, and the insertion of the optical fibers 651 to 654 can be made easier. Furthermore, as will be described later, the case where the outer diameters of the ferrule 631 and the ferrule 633 or the ferrule 632 and the ferrule 634 are different can be dealt with.

  With such a configuration, the arrangement of the WDM filter 602 is a case where the total length in the direction in which the optical fibers 651 to 654 of the WDM filter 602 are drawn out is longer than that of the WDM filter module of the fourth embodiment. In addition, the total length of the WDM filter module can be shortened. Further, since the lengths of the optical fibers 651 to 654 from the WDM filter 602 to the ferrules 631 to 634 are long, polishing of the end faces of the ferrules 631 to 634 and incorporation into the housing 601 are relatively easy.

  Since the plugs 611 and 612 are inserted into the jacks of the optical transceiver module, the WDM filter 602 and the optical fibers 651 to 654 cannot be disposed in the vertical and horizontal spaces of the plugs 611 and 612. . Since the width or height of the WDM filter module depends on the fixed position of the WDM filter 602, the position of the WDM filter 602 is appropriately determined according to the usage pattern of the WDM filter module.

  Referring to the fourth and fifth embodiments, the WDM filter module of the sixth embodiment is changed to correspond to an optical transceiver module for one-fiber bidirectional transmission having one transmission / reception port. can do.

(Seventh embodiment)
FIG. 15 shows a WDM filter module according to the seventh embodiment of the present invention. FIG. 15A is a transverse sectional view seen from above, and FIG. 15B is a longitudinal sectional view seen from the side. The WDM filter module of the seventh embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. The WDM filter module of the seventh embodiment has the same configuration as the WDM filter module of the fourth embodiment.

  The four ferrules 731 to 734 are independent from each other, and their relative positions can be changed by the wiring of the optical fibers 751 to 754. When the WDM filter module is connected to the optical transceiver module, the plugs 711 and 712 are connected to the ferrules 731 and 732 in order to realize a PC with the ferrule end face of the jack of the optical transceiver module and the end faces of the ferrules 731 and 732. Springs 743 and 744 for pressing against the jack on the optical transceiver module side along the axial direction are respectively incorporated.

  The ferrules 733 and 734 are limited in the amount of movement in the axial direction by the housing 701, and when a transmission optical fiber plug is connected, the PC at each end surface is realized by the pressing force of the spring built in the plug. The

  An area for incorporating the springs 743 and 744 into the WDM filter module is required. For example, since this region fits within the plug structure of the MU type optical connector, there is almost no increase in the total length of the WDM filter module based on the built-in spring. In other words, the total length of the WDM filter module is approximately the same as that of the WDM filter module of the fourth embodiment.

  When the optical fibers 751 to 754 are inserted into the ferrules 731 to 734 and bonded, or when the end surfaces of the ferrules 731 to 734 are polished, the ferrules 731 to 734 can be handled independently, so that polishing becomes easy.

(Eighth embodiment)
FIG. 16 shows a WDM filter module according to the eighth embodiment of the present invention. The WDM filter module of the eighth embodiment corresponds to an optical transceiver module for one-fiber bidirectional transmission having one transmission / reception port. The WDM filter module of the eighth embodiment has a structure in which the plug 812 is removed from the WDM filter module of the seventh embodiment.

  The positions of the three ferrules 831, 833, and 834 can be relatively changed. There is no need to align the optical axis of the plug 811 and the optical axis of the jack 821.

(Ninth embodiment)
FIG. 17 shows a WDM filter module according to the ninth embodiment of the present invention. FIG. 17A is a cross-sectional view seen from above, and FIG. 17B is a vertical cross-sectional view seen from the side. The WDM filter module of the ninth embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. The WDM filter 902 is disposed above the jacks 921 and 922 and is fixed to the housing 901.

  Four optical fibers 951 to 954 are used for optical input / output with respect to the WDM filter 902. The four optical fibers 951 to 954 are taken out only from one side of the WDM filter 902. The direction in which the optical fibers 951 to 954 are pulled out is the axial direction from the jack 921 toward the plug 911. However, the specific position of the WDM filter 902 is determined in consideration of the allowable value of the bending radius of the optical fibers 951 to 954.

  If the dimensions of the WDM filter 902 are less than the dimensions of the jacks 921 and 922, the WDM filter 902 can be installed on top of the jacks 921 and 922. Therefore, although the height of the WDM filter module increases, the overall length and width are Does not increase.

(Tenth embodiment)
FIG. 18 shows a WDM filter module according to the tenth embodiment of the present invention. The WDM filter module of the tenth embodiment corresponds to an optical transceiver module for two-core bidirectional transmission having two ports, a reception port and a transmission port. In the WDM filter module, a WDM filter 1002 that combines and demultiplexes an optical signal according to a wavelength is fixed to a housing 1001. The fixed position of the WDM filter 1002 may be the lower or upper portion of the WDM filter module, that is, the side surface in the vertical direction, in addition to the side surface in the horizontal direction.

  In the WDM filter module, two ports to be fitted and connected to the jack of the optical connector of the optical transceiver module are composed of two plugs 1011 and 1012. On the other hand, the two ports fitted and connected to the transmission optical fiber plug on the accommodation station side are composed of jacks 1021 and 1022, respectively. The housing 1001 has a structure in which plugs 1011 and 1012 and jacks 1021 and 1022 are coupled together.

  The four ferrules 1031 to 1034 are independent from each other, and the relative positions can be changed by the wiring of the optical fibers 1051 to 1054. When the WDM filter module is connected to the optical transceiver module, the ferrules 1031 and 1032 are pivotally connected to the plugs 1011 and 1012 in order to realize a PC with the ferrule end face of the jack of the optical transceiver module and the end faces of the ferrules 1031 and 1032. Springs 1043 and 1044 for pressing in the direction are built in, respectively.

  Four optical fibers 1051 to 1054 are used for optical input / output with respect to the WDM filter 1002. The four optical fibers 1051 to 1054 are taken out only from one side of the WDM filter 1002. The direction in which the optical fibers 1051 to 1054 are pulled out is the horizontal direction. However, the specific position of the WDM filter 1002 is determined in consideration of the allowable value of the bending radius of the optical fibers 1051 to 1054.

  The central axes (ferrule axes) of the plugs 1011 and 1012 and the jack 1021 are in the same direction as the central axis of the jack of the optical transceiver module to be connected, but the central axis of the jack 1022 faces the lateral direction perpendicular thereto. Yes. Thereby, the plug of the transmission optical fiber is also connected to the jack 1022 from the lateral direction. Such a configuration is suitable when the wiring direction of the transmission optical fiber connected to the jack 1022 is the horizontal direction. In the WDM filter module of the seventh embodiment, it is necessary to bend the transmission optical fiber connected to the jack 1022 by 90 °, and a space for that is required.

  Further, when a tensile force acts on the transmission optical fiber connected to the jack 1022, the bending moment applied to the connection portion between the plugs 1011 and 1012 and the optical transceiver module can be made relatively small.

For plugs 1011 and 1012
(A) Jack 1021 is axial, jack 1022 is upward,
(B) Make the jacks 1021, 1022 sideways and opposite,
(C) Both jacks 1021, 1022 face down,
(D) Both jacks 1021 and 1022 face up,
(E) Jack 1021 faces downward and jack 1022 faces upward
It is possible to take a configuration such as In this way, the WDM filter module may be configured according to the wiring direction of the transmission optical fiber to be connected. A structure in which the axial direction of the jacks 1021 and 1022 is inclined by 45 ° with respect to the axial direction of the plugs 1011 and 1012 is also conceivable.

  Such various types of WDM filter modules have the same configuration if a WDM filter from which an optical fiber is drawn out only from one side of the main body is used and a configuration in which the WDM filter and each ferrule are connected by an optical fiber is employed. This can be realized using a WDM filter. A WDM filter module corresponding to a single-core optical transceiver module can also realize the same configuration as described above.

(Optical connector)
In the WDM filter module described in the first to tenth embodiments, as an interface (jack) of an optical transceiver module, a plug and jack of a WDM filter module, and a plug of an optical fiber for transmission, an SC type optical connector, an MU type optical A connector or a connector compatible with an LC type optical connector can be applied. The outer shape of the ferrule is 2.5 mm for SC type and 1.25 mm for MU type and LC type. When the interface of the optical transceiver module is MU type or LC type, the distance between the axes of the two parallel ferrules is usually 6.25 mm. Accordingly, the distance between the axes of the plugs of the WDM filter module is also 6.25 mm.

  When the jack of the WDM filter module is MU type or LC type, since the ferrule is relatively thin and the thickness of the split sleeve is small, the strength at the connection point is relatively low. Therefore, in the case of these types of optical connectors, as described above, it is necessary to make the total length of the WDM filter module as short as possible so that the bending moment due to the external force applied to the connection portion between the optical transceiver module and the WDM filter module is reduced. is there.

  When the interface of the optical transceiver module is LC type, the plug of the WDM filter module is LC type, the jack is MU type, and the transmission optical fiber plug is MU type. In this way, the WDM filter module can have a function of converting the type of the optical connector. When the ferrule is made into an integral structure after end face polishing, or when the spring is attached with the ferrule being independent, the plug and the jack can be made SC type and MU type having different ferrule diameters.

(Optical fiber)
In the WDM filter module described in the first to tenth embodiments, the total length of the module greatly depends on the allowable value (lower limit) of the bending radius of the optical fiber connecting the WDM filter and the ferrule. Therefore, in order to shorten the overall length, an optical fiber having a clad diameter as small as about 80 μm and a large relative refractive index difference between the core and the clad of 0.75% or more is used. Preferably, an optical fiber capable of setting the allowable value of the bending radius to about 10 mm or less, particularly about 5 mm is used.

  When the portion corresponding to the core or the clad is composed of a plurality of portions having different refractive indexes, such as dispersion shifted fiber and photonic crystal fiber, the relative refractive index difference is effective (equivalent). Replaced by the relative refractive index difference. In such an optical fiber, even if the bending radius is reduced to 10 mm or less, radiation loss (bending loss) due to bending can be sufficiently reduced at a normal wavelength used in optical communication.

  In more general terms, in order to reduce the bending radius and the bending loss, the V value using the relative refractive index difference, the core diameter, and the wavelength as parameters is increased. If the optical fiber has a small diameter, even if the bending radius is small as described above, the mechanical reliability against bending, that is, the reliability that the optical fiber is not broken even when the optical fiber is bent for a long period of time is high. This is because, even if the bending radius is the same, the maximum tensile stress or the maximum compressive stress in the cross section is smaller in the small-diameter fiber than in the optical fiber having a cladding diameter of about 125 μm. In order to further increase the mechanical reliability of optical fiber bending, a screening test is performed in which a WDM filter module is bent at a radius smaller than the bending radius after the manufacturing to check for breakage. Good. The cladding diameter of the optical fiber is about 80 μm, but in principle, a diameter smaller than that is also possible.

  In the above-described optical fiber having a large relative refractive index difference, the core diameter is small and the mode field diameter (MFD) is as small as about 7 μm or less in order to obtain single mode characteristics. When the optical fiber in the jack of the optical transceiver module to which the WDM filter module is connected or the MFD of the optical fiber for transmission is about 10 μm, connection loss occurs due to the difference in MFD. Therefore, when the MFD of the optical fiber is enlarged only in the vicinity of the end face of the ferrule, the connection loss can be reduced. In order to expand the MFD, a method of expanding the core by heating is known.

  It is also conceivable to use an optical fiber having a relatively large core diameter and an MFD of about 7 to 10 μm. However, such an optical fiber has multi-mode characteristics, and a part of the optical power is coupled to a waveguide mode higher than the first-order mode, resulting in a loss. The MFD is designed in consideration of total connection loss, bending loss, and the like.

(Other components)
If the optical fiber has a coating in a region between the WDM filter and the ferrule, it can be prevented from being damaged and broken. It is also conceivable to make the wiring pattern more appropriate by partially restraining the optical fiber in this region.

  The housing can be manufactured at low cost by using plastic as a material and using an injection molding method as a manufacturing method. In general optical connectors, ferrules made of ceramic (mainly zirconia) or glass (including crystallized glass) are used. In order to reduce the manufacturing cost, a plastic ferrule manufactured by an injection molding method can be used in the WDM filter module.

  In the first to tenth embodiments, a pluggable optical module having various functions can be configured by mounting other types of functional elements instead of the WDM filter. For example, a pluggable optical monitor module can be obtained by mounting an optical monitor element that extracts a part of the power of an optical signal and converts it into an electrical signal. At this time, it is good also as a structure which has three or more plugs and jacks.

  In the first to tenth embodiments, the ferrule is cylindrical and accommodates only one optical fiber, and the plug or jack has a structure of a so-called single-core optical connector. On the other hand, a multi-core ferrule that houses a plurality of optical fibers in one member, such as a ferrule of an MT-type optical connector, may have a plug or jack portion having a multi-fiber optical connector structure. it can.

  Although the WDM filter module shown in the first to tenth embodiments is assumed to be directly coupled to the optical transceiver module, it can be used in other cases. For example, when a pigtail type optical transceiver module to which an optical fiber is permanently connected is mounted in an optical transceiver, and the optical fiber is connected to a jack of an optical connector provided on a side surface of the optical transceiver, The WDM filter module is connected to a jack on the side surface of the casing.

  The WDM filter module corresponding to the optical transceiver module for one-fiber bidirectional transmission shown in the first to tenth embodiments and the WDM filter module corresponding to the optical transceiver module for two-fiber bidirectional transmission are similar steps. Can be produced.

It is a figure which shows the structure of the WDM transmission system to which the optical transmission / reception apparatus which performs the conventional bidirectional transmission is applied. It is a figure which shows the structure of the WDM transmission system to which the optical transmission / reception apparatus which performs bidirectional transmission with the conventional one optical fiber is applied. It is sectional drawing which shows the structure of the conventional WDM filter module for two-core bidirectional transmission. It is sectional drawing which shows the structure of the 1st example of the conventional WDM filter. It is sectional drawing which shows the structure of the 2nd example of the conventional WDM filter. It is sectional drawing which shows the structure of the WDM filter module for the conventional 1-fiber bidirectional | two-way transmission. It is sectional drawing which shows the WDM filter module concerning the 1st Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 2nd Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 3rd Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 4th Embodiment of this invention. It is a block diagram which shows an example of the WDM filter of the WDM filter module concerning 4th Embodiment. It is sectional drawing which shows the WDM filter module concerning the 5th Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 6th Embodiment of this invention. It is a block diagram which shows an example of the WDM filter of the WDM filter module concerning 6th Embodiment. It is sectional drawing which shows the WDM filter module concerning the 7th Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 8th Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 9th Embodiment of this invention. It is sectional drawing which shows the WDM filter module concerning the 10th Embodiment of this invention.

Explanation of symbols

101 Housing 102 WDM Filter 111, 112 Plug 121, 122 Jack 131-134 Ferrule 141, 142 Split Sleeve 151-154 Optical Fiber 161 Locking Piece 135, 136 Ferrule Member

Claims (11)

One or more plug structures coupled to the jack of the optical connector and incorporating a cylindrical ferrule;
One or more jack structures that couple to the plug of the optical connector and contain a cylindrical ferrule;
A plurality of input / output optical fibers accommodated in the ferrule are connected, and predetermined multiplexing / demultiplexing according to the wavelength is executed on the optical signal input through the plurality of input / output optical fibers. A WDM filter for outputting to the plurality of input / output optical fibers;
Including a housing part of the plug structure and the jack structure and a housing part for accommodating the WDM filter, and a housing constituted by an integral member,
The optical fiber for input / output has a portion that is not mechanically constrained between the ferrule and the WDM filter so that the position of the ferrule can be freely changed in the housing. module.   The ferrule built into one of the plug structures and the ferrule built into one of the jack structures are integrated so that the respective optical axes facing each other are aligned. The WDM filter module according to claim 1.   The ferrule built into one of the plug structures and the ferrule built into one of the jack structures are integrated via a third member. 2. The WDM filter module according to 2.   2. The WDM filter module according to claim 1, wherein the plug structure includes a spring for pressing a built-in ferrule toward a jack side of the optical connector along an optical axis direction.   At least one of the jack structures has an optical axis direction of a built-in ferrule having an angle of 45 ° or more and 90 ° or less with respect to an optical axis direction of the ferrule built in the plug structure. Item 5. The WDM filter module according to Item 4.   6. The WDM filter module according to claim 1, wherein the input / output optical fiber is taken out only from one side of the WDM filter.   The WDM filter module according to claim 6, wherein the WDM filter is fixed in contact with a plurality of housing portions of the jack structure.   8. The WDM filter module according to claim 1, wherein the plug structure and the jack structure are compatible with a MU type optical connector.   8. The WDM filter module according to claim 1, wherein the plug structure and the jack structure are compatible with an LC type optical connector.   The WDM filter module according to claim 1, wherein the WDM filter performs multiplexing / demultiplexing using a multilayer interference filter. 8. The input / output optical fiber according to claim 1, wherein an effective relative refractive index difference between the core portion and the clad portion is 0.75% or more and a clad outer diameter is 90 μm or less. The WDM filter module described in 1.

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