JP2009265121A - Optical transceiver module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To connect a POF cord to a light receiving element without using a high-accuracy ferrule or sleeve. <P>SOLUTION: The optical transceiver module 10 includes: a case 11; a module 12; a fiber insertion guide 13 and a fiber fixing cap 14. The module body 12 is an integral resin molding, which includes the light receiving element 20. A light condensing lens part 23 and an expanding guide surface 25 are formed on the side of the light receiving surface 20a of the light receiving element 20. The expanding guide surface 25 is formed into a conical shape, and the chip surface 15a of the POF cord 15 is made to abut on the expanding guide surface 25 by means of the fiber fixing cap 14. The optical axis CL1 of the POF cord 15 is aligned with the optical axis CL2 of the light receiving element 20. The optical axis of the POF cord 15 and the optical axis of the light receiving element 20 are simply and easily aligned with each other without using the high-accuracy ferrule or sleeve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical transceiver module in which an optical device and a lens are integrated and used in an optical signal transmission system.

  As a conventional optical transmission system, for example, as disclosed in Patent Document 1, a configuration using a single mode fiber in a transmission path is known. In an optical signal transmission system using a single-mode fiber in a transmission path, a signal generated by modulating a signal such as video, audio, data (hereinafter referred to as a modulation signal) is a laser module via a laser driving circuit. Is input. In the laser module, an optical signal whose intensity is modulated based on the modulation signal (hereinafter referred to as an optical modulation signal) is generated. The optical modulation signal passes through the optical transmission path, is sent to the light receiving module, is again converted into a modulation signal, is output, and then demodulated to the original signal.

  The laser module includes a laser diode, a condenser lens group, and a pigtail. The pigtail includes an isolator, an optical fiber, and an optical connector. The modulation signal input to the laser module is converted into an optical modulation signal in the laser diode. The light modulation signal is condensed on the fiber incident surface of the optical fiber by the condenser lens group, and a light modulation signal having a sufficient amount of light is incident on the optical fiber.

  The optical modulation signal is propagated in an optical transmission path including an optical connector connected to the optical connector of the pigtail and an optical fiber, and is emitted from the fiber exit surface. The emitted light modulation signal is condensed on the light receiving surface of the light receiving element by the condensing lens and converted into a modulation signal by the light receiving element. The reproduced modulated signal passes through an amplifier and is output.

  In a conventional optical signal transmission system, a single mode optical fiber (SMF) is used as an optical fiber from the viewpoint of reducing the generation of modal noise. Along with this, a distributed feedback laser diode (DFB-LD) that oscillates in a single mode has been used as a projector. When the reflected return light of the light modulation signal reaches the laser diode, noise increases. For this reason, it is necessary to make the optical connector a physical coupling type (for example, PC coupling) having a small amount of return loss and to sufficiently polish the end face of the optical fiber in the optical connector. In addition, in order to prevent reflection at the light receiving surface of the light receiving element from returning to the optical transmission path, the exit surface of the optical fiber is disposed obliquely with respect to the light receiving element. Further, the reflected return light is reduced by providing an optical isolator on the pigtail.

Patent Documents 2 and 3 disclose an aspect in which analog optical signal communication is performed using a multimode optical fiber instead of using a single mode glass optical fiber. In the cited document 4, an optical transceiver having high optical and mechanical accuracy and high reliability is disclosed.
Japanese Unexamined Patent Publication No. 63-218909 JP 2004-266663 A JP 2005-318532 A JP-A-11-168233

  As described above, when optical communication is performed using a single mode optical fiber or a multimode optical fiber, it is necessary to accurately align the optical axes of the optical fiber and each transceiver module. For this reason, for example, as shown in cited document 4, it is necessary to use a highly accurate ferrule or sleeve, and there is a problem that the construction cannot be performed easily and inexpensively.

  The present invention is for solving the above-mentioned problems, and can eliminate the need for a high-precision ferrule or sleeve so that the connection work can be performed easily and easily, and the coupling loss caused by the coupling axis deviation from the optical fiber can be reduced. An object of the present invention is to provide an optical transceiver module that can be manufactured at low cost.

  In order to achieve the above object, according to the present invention, an optical fiber is connected and has a light receiving surface or a light projecting surface for an optical signal transmitted through the optical fiber, and the optical signal and an electrical signal corresponding to the optical signal. A light having an optical device that converts one of the signals into the other signal, and a lens disposed between the optical device and the optical fiber so as to face the light receiving surface or the light projecting surface of the optical device In the transceiver module, the optical device is built in, and a transparent resin molded body in which the lens is integrally formed, and is formed in a peripheral portion of the lens of the transparent resin molded body, and the tip of the optical fiber is abutted. An expanding guide surface formed of a conical surface, a case in which the transparent resin molded body is accommodated, and provided in the case, holding the optical fiber, an optical fiber tip on the expanding guide surface Characterized in that it comprises an optical fiber holding member shed to.

  In addition, by pressing the optical fiber tip to the spread guide surface by the optical fiber holding member, the center axis of the spread guide surface coincides with the center position of the light receiving surface or the light projecting surface of the optical device, And it is preferable to be orthogonal to the light receiving surface or the light projecting surface. Further, the transparent resin molded body may be held in the case so as to be movable in a direction perpendicular to the optical axis of the optical fiber within a range where the tip of the optical fiber is located within the opening of the spreading guide surface. preferable.

  According to the present invention, the optical axis of the optical device and the optical axis of the optical fiber can be easily aligned. Therefore, the conventional high-precision ferrule and sleeve are not required, and these can be easily and easily joined together with the optical axes of the optical transceiver module and the optical fiber being aligned.

  As shown in FIG. 1, the optical transceiver module 10 of the present invention includes a case 11, a module body 12, a fiber insertion guide 13, and a fiber fixing cap 14. A plastic optical fiber (hereinafter simply referred to as POF) cord 15 is connected to the optical transceiver module 10.

  In this embodiment, the POF code 15 is composed of a great index (GI) type POF strand 16 and a covering portion 17. The GI-type POF strand 16 is configured such that the refractive index gradually increases toward the center in the radial direction. Currently, there are two types of diameters of the POF strands 750 μm and 1 mm. Any of these may be used, and the present invention is applied to those having an outer diameter other than these. Can be applied. The covering portion 17 may be omitted. In this case, the POF strand 16 is used as it is as an optical fiber.

  The end portion of the POF cord 15 has a covering portion 17 cut off, and the POF strand 16 is exposed. In addition, the tip processing is performed so that the tip of the POF strand 16 is perpendicular to the central axis of the POF strand 16.

  The module body 12 is composed of a transparent resin molded body 21 containing a light receiving element 20 as an optical device, and an electronic circuit board 22 that processes an electrical signal converted from an optical signal by the light receiving element 20. An electrical component 22 a is attached to the electronic circuit board 22.

  A condensing lens portion 23 formed integrally with the module body 12 is formed in the module body 12 at a position facing the light receiving element 20. The condensing lens unit 23 condenses the optical signal from the POF code 15 connected to the optical transceiver module 10 and makes it incident on the light receiving surface 20 a of the light receiving element 20.

  A conical recess 24 is formed in the transparent resin molding 21 on the light signal incident side of the condenser lens portion 23. The conical surface of the recess 24 is an expanded guide surface 25, and the distal end surface 15 a of the POF cord 15 is abutted against the expanded guide surface 25. The central axis of the conical recess 24 constituting the spread guide surface 25 coincides with the center position of the light receiving surface 20a of the light receiving element 20 and is orthogonal to the light receiving surface 20a. As a result, when the front end surface 15a of the POF code 15 is abutted against the expansion guide surface 25, the POF code 15 is guided to the expansion guide surface 25, and the optical axis CL1 of the POF code 15 and the light receiving element 20 receive light. The center axis (optical axis) CL2 of the surface 20a coincides.

  The expansion guide surface 25 has a minimum diameter of 750 μm or less in accordance with the outer diameter standard of GI type POF strands 16 currently provided, 750 μm, and 1 mm, and the maximum diameter takes into account the ease of insertion. For example, it is formed in about 3 mm. In this case, it can be used for two types of GI POFs of 750 μm and 1 mm. In addition, you may form the exclusive expansion guide surface 25 according to each GI type | mold POF of 750 micrometers and 1 mm, without setting it as such a combined use type.

  The case 11 fixes the module main body 12 and accommodates it inside, and is comprised from the case main body 11a, the cover part 11b, and the attachment stay 11c. Although not shown, the case 11 is provided with a connector. The connector includes a terminal connected to the electronic circuit board 22 and can be electrically connected to an external communication device. The cord may be pulled out from the case 11 instead of the connector.

  A fiber insertion guide 13 is formed integrally with the case 11. Although this fiber insertion guide 13 functions as a conventional sleeve, unlike a sleeve that is required to have high dimensional accuracy so that the optical axis of the POF code is aligned with the optical axis CL2 of the light receiving element 20, The POF cord 15 is formed in a cylindrical shape that can be inserted.

  In addition, the case 11 is formed with a female screw portion 30 as an attachment portion of the fiber insertion guide 13. The module main body 12 is securely fixed in the case 11 by screwing the male screw portion 31 formed on the outer peripheral surface of the fiber insertion guide 13 into the female screw portion 30. Note that, instead of or in addition to such a fixing method, fixing may be performed by screws or adhesion. In this embodiment, in order to prevent the fiber insertion guide 13 from coming off from the case 11, the attachment portion is fixed after screwing using an adhesive, but is simply fixed using a lock nut or other fixing means. May be.

  The fiber fixing cap 14 includes a cap body 40, a coil spring 41, and a pressing ring 42. An internal thread portion 43 and a stopper 44 are formed on the inner peripheral surface 40 a of the cap body 40. The female thread portion 43 is screwed into the cap mounting male thread portion 45 of the fiber insertion guide 13. The stopper 44 is for restricting the movement of the pressing ring 42 and the coil spring 41 in the cap body 40, and for preventing the pressing ring 42 and the coil spring 41 from dropping from the inner peripheral surface of the cap body 40. A locking surface 44a for locking the ring 42 is provided. The coil spring 41 urges the pressing ring 42 toward the module main body 12 side. The cap body 40 includes a lid portion 40b. By removing the lid 40b, the pressing ring 42 and the coil spring 41 are housed inside. Further, the pressing ring 42 and the coil spring 41 are accommodated in the cap body 40 by fixing the lid portion 40 b to the cap body 40.

  The pressing ring 42 includes a plurality of claws 46 on the inner peripheral surface. The claw 46 has a spring property. As a result, when the POF cord 15 is inserted, it is not locked to the covering portion 17 and can be easily inserted. Further, when pulling out in the direction opposite to the insertion, the claw 46 bites into the covering portion 17. Therefore, the covering portion 17 is fixed to the pressing ring 42 via the claw 46. Then, the POF code 15 is biased by the coil spring 41 so as to approach the light receiving element 20 in the direction of the optical axis CL2 of the light receiving element 20. By this energization, even if the optical axis CL1 of the POF code 15 is deviated from the optical axis CL2 of the light receiving element 20, the front end surface 15a of the POF code 15 is guided against the widening guide surface 25. The optical axis CL1 of the POF code 15 coincides with the optical axis CL2 of the light receiving element 20. Further, since the expanding guide surface 25 is formed so that the central axis of the conical surface of the recess 24 coincides with the light receiving surface 20 a of the light receiving element 20, the distal end surface 15 a of the POF cord 15 is expanded guide surface 25. , The optical axis CL1 of the POF code 15 becomes perpendicular to the light receiving surface 20a.

  The coil spring 41 and the pressing ring 42 constitute the POF code urging means of the fiber fixing cap 14. However, the present invention is not limited to these forms, and the function of pressing the POF code 15 against the expansion guide surface 25. What is necessary is just to have.

  Next, the operation of this embodiment will be described. When attaching the POF code 15 to the optical transceiver module 10, first, the tip surface 15a of the POF code 15 is cut at right angles to the optical axis CL1 by tip processing. Further, the covering portion 17 is peeled off from the tip surface 15a by L1. These can be performed quickly by using a dedicated processing tool.

  Next, the POF cord 15 is inserted into the fiber fixing cap 14, and the POF cord 15 is inserted into the pressing ring 42 so that the front end surface 15 a of the POF cord 15 protrudes from the fiber fixing cap 14 by a predetermined length. When the POF cord 15 is pulled so as to be pulled out after being stopped at a predetermined position after the POF cord 15 is inserted, the claw 46 bites into the covering portion 17, and the POF cord 15 is fixed to the inner peripheral surface of the pressing ring 42.

  In this state, the fiber fixing cap 14 is inserted into the fiber insertion guide 13 of the case 11 and screwed. As the fiber fixing cap 14 is screwed in, the tip surface 15a of the POF cord 15 abuts against the expansion guide surface 25 by the bias of the coil spring 41, and the optical axis CL1 of the POF code 15 and the optical axis CL2 of the light receiving element 20 coincide. In addition, the optical axis CL1 of the POF code 15 is orthogonal to the light receiving surface 20a of the light receiving element 20.

  As described above, in the present embodiment, by using the expanding guide surface 25 and the urging means for urging the POF cord 15 toward the expanded guide surface 25, highly accurate parts such as ferrules and sleeves that have been conventionally required are used. Therefore, the optical axis CL1 of the POF code 15 and the optical axis CL2 of the light receiving element 20 can be easily matched.

  In the above embodiment, an example in which the light receiving element 20 is used as an optical device of the optical transceiver module has been described. However, a light emitting element may be used as the optical device.

  Next, an optical analog signal transmission system using an optical transceiver module and a POF code will be described with reference to FIG. The optical analog signal transmission system 50 includes a laser module 51 that converts a carrier modulation signal into an optical modulation signal, a POF code 52 that transmits the optical modulation signal, and a light receiving module 53 that converts the optical modulation signal into a carrier modulation signal. Has been. The laser module 51 is an optical transceiver module of the present invention using a laser diode 56 as an optical device, and the light receiving module 53 is an optical transceiver module of the present invention using a light receiving element 62 as an optical device.

  The carrier modulation signal is generated by modulating a baseband signal such as video, audio, or data with a carrier (sine wave) in the modulator 54. Here, when the baseband signal is an analog signal, it is modulated by an analog modulation method such as AM (Amplitude Modulation) or FM (Frequency Modulation). On the other hand, when the baseband signal is a digital signal, it is modulated by a digital modulation method such as PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation). The carrier modulation signal is input to the laser module 51 via the amplifier 55.

  The carrier modulation signal input to the laser module 51 is converted into an optical modulation signal by a laser diode 56 that emits laser light in the visible light range. The light modulation signal is condensed on the fiber incident surface 52 a of the POF code 52 by the condenser lens unit 60, and a light modulation signal having a sufficient amount of light is incident on the POF code 52.

  The optical modulation signal is propagated in the POF code 52 and emitted from the fiber exit surface 52b. The emitted light modulation signal is converted into a modulation signal by the light receiving element 62 through the condenser lens unit 61, and is output through the amplifier 63.

  When constructing such an optical signal transmission system, by using the optical transceiver module of the present invention, the optical axis of the optical device and the optical axis of the POF code can be matched easily and easily with high accuracy. . In the above embodiment, the optical analog signal transmission system has been described as an example. However, the present invention may be implemented in an optical digital signal transmission system.

  Next, with reference to FIG. 3, the optical transceiver module 70 which is 2nd Embodiment of this invention is demonstrated. This optical transceiver module 70 has a simplified configuration of a case 71 as a POF code holding member and a fiber fixing cap 72. The module main body 73 is also formed by integrating a photodiode 75 and a substrate 76 thereof, an electronic component 77 and a substrate 78 thereof, a lead frame 79 and the like in a transparent resin molded body 74. The transparent resin molded body 74 is formed in a rectangular parallelepiped shape, but this may be a cylindrical body shape or other shapes. A lead wire (not shown) is connected to the lead frame 79, and a signal is sent to the outside of the case 71 through the lead wire. In this embodiment, the case of using as a light receiver is taken as an example. However, in the case of using as a light projector, for example, an LED or a laser diode may be arranged instead of the photodiode 75.

  The case 71 includes a base portion 71a and a POF code holding portion 71b. A storage hole 82 is formed in the base 71 a, and the module main body 73 is stored in the storage hole 82. After the module main body 73 is stored, the lid 83 that fits into the storage hole 82 is attached to the case 71, and the module main body 73 is fixed to the case 71.

  The POF cord holding portion 71b is formed in a stepped columnar shape whose diameter gradually decreases toward the tip, and a cord storage hole 85 is formed along the center line. The code storage hole 85 stores the POF code 86. The POF code 86 includes a POF strand 87 and a covering portion 88 that covers the POF strand 87. The cord housing hole 85 is a stepped hole, and the distal end surface and the stepped portion of the covering portion 88 are in a state where the distal end 87a of the POF strand is in contact with the expansion guide surface 73a of the module main body 73 as will be described later. It abuts on 85a or is fixed with a slight gap.

  A locking claw 90, a cord holding shaft 91, a tapered portion 92, and a male screw portion 93 are formed in this order from the tip on the outer peripheral surface of the POF cord holding portion 71b. Further, three slits 94 are formed in the axial direction in the POF code holding portion 71b at a pitch of 120 ° in the circumferential direction. The slit 94 provides flexibility to the cord holding shaft portion 91 and the taper portion 92. As will be described later, when the fiber fixing cap 72 is screwed into the POF cord holding portion 71b, the fiber fixing cap 72 is provided. The tapered portion 95 on the side engages with the tapered portion 92 and presses the tapered portion 92, whereby the tapered portion 92 and the cord holding shaft portion 91 divided by the slit 94 are pressed inward. By this pressing, the outer peripheral surface of the POF cord 86 is pressed and held, so that the POF cord 86 does not fall off from the POF cord holding portion 71b.

  The fiber fixing cap 72 is formed in a cylindrical shape, and includes a tapered portion 95, a female screw portion 96, a mounting shaft portion 97, and a locking portion 98 so as to correspond to the POF cord holding portion 71b. When the female screw portion 96 is screwed into the male screw portion 93 of the POF cord holding portion 71b and the taper portions 92 and 97 are brought into close contact with each other, the cord holding shaft portion 91 is deformed so as to be pushed inward and holds the POF cord 86. Prior to this screwing, the POF cord 86 is housed in the cord housing hole 85, and the tip 87 a is pressed so as to abut against the expansion guide surface 73 a of the module body 73. As a result, when the fiber fixing cap 72 is screwed, the tip 87a of the POF strand 87 moves along the widening guide surface 73a, and the movement of the widening guide surface 73a causes the center of the light receiving surface 75a of the photodiode 75 to move. And the center of the POF strand 87 coincide.

  In addition to fixing the module main body 73 in the case 71, although not shown in the figure, a gap is provided between the storage hole 82 and the module main body 73 in a direction perpendicular to the center line of the POF strand 87. It may be movable. In this case, when the opening diameter of the expanding guide surface 73a is D1 and the outer diameter of the tip of the POF strand 87 is D2, the center distribution of the cord housing hole 85 is centered (D1-D2). ), The transparent resin molded body 74 is movable in a direction perpendicular to the optical axis of the POF cord 86. As a result, the tip of the POF strand 87 is always positioned within the opening of the spreading guide surface 73a, and the tip of the POF strand 87 can be reliably opposed to the light receiving surface 75a.

It is sectional drawing which shows the joining state of the optical transceiver module of this invention, and a POF cord. It is a schematic block diagram of an optical signal transmission system. FIG. 9 is a cross-sectional view showing a second embodiment of the present invention and showing a joining state of an optical transceiver module and a POF cord.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical transceiver module 11 Case 12 Module main body 13 Fiber insertion guide 14 Fiber fixing cap 15 POF cord 15a Tip surface 16 POF strand 17 Covering part 20 Light receiving element 21 Transparent resin molding 23 Condensing lens part 25 Expansion guide surface 41 Coil spring 42 Pressing Ring 44 Stopper 51 Laser Module 52 POF Code 53 Light Receiving Module 70 Optical Transceiver Module 71 Case 72 Fiber Fixing Cap 73a Expanding Guide Surface 73 Module Main Body 74 Transparent Resin Molded Body 75 Photodiode

Claims (3)

An optical fiber is connected and has a light receiving surface or a light projecting surface for an optical signal transmitted through the optical fiber, and converts either the optical signal or an electrical signal corresponding to the optical signal into the other signal. An optical transceiver module, and an optical transceiver module having a lens disposed between the optical device and the optical fiber so as to face a light receiving surface or a light projecting surface of the optical device.
A transparent resin molded body in which the optical device is incorporated and the lens is integrally formed;
An expansion guide surface formed of a substantially conical surface formed on the periphery of the lens of the transparent resin molded body and against which a tip of the optical fiber is abutted,
A case in which the transparent resin molded body is stored;
An optical transceiver module, comprising: an optical fiber holding member that is provided in the case and holds the optical fiber and presses the tip of the optical fiber against the spread guide surface.   By pressing the tip of the optical fiber against the spread guide surface by the optical fiber holding member, the center axis of the spread guide surface coincides with the center position of the light receiving surface or the light projecting surface of the optical device, and The optical transceiver module according to claim 1, wherein the optical transceiver module is orthogonal to the light receiving surface or the light projecting surface.   The transparent resin molded body is movably held in the case in a direction perpendicular to the optical axis of the optical fiber within a range in which the tip of the optical fiber is positioned within the opening of the expansion guide surface. The optical transceiver module according to claim 1 or 2.

Images