JP2006276631A - Aligning method of optical coupling module and measuring beam emission device for alignment of optical coupling module and optical coupling module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure alignment between a sleeve to which the connector of an optical communication cable is connected so as to be attachable and detachable and a holder on which a light receiving element is mounted with high precision. <P>SOLUTION: In this aligning method of an optical coupling module, in order to perform alignment between the sleeve 5 in which a condensing lens 9 is incorporated and the holder 6 on which a photodiode 10 is mounted, a measuring beam emission device 30 for alignment is connected to the sleeve 5, a light beam emitted from its graded index type multimode optical fiber 34 irradiates the light receiving surface 10a of the photodiode 10, so that the spot diameter of the light beam becomes a spot diameter which is sufficiently larger than the light receiving surface 10a on the light receiving surface 10a of the photodiode 10, and positions of the sleeve 5 and the holder 6 are adjusted so that the received light quantity by the photodiode 10 becomes the maximum received light quantity, and when the received light quantity by the photodiode 10 becomes the maximum, the sleeve 5 and the holder 6 are fixed by welding means, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides an optical coupling module to which an optical communication cable is detachably connected, and constitutes the optical coupling module to align a sleeve to which a connector is detachably connected and a holder in which a light receiving element is incorporated. The present invention relates to a method for aligning optical coupling modules, a measuring light irradiation device for alignment of optical coupling modules used for this alignment, and further to an optical coupling module aligned in this manner.

  An optical fiber is used as a signal transmission path in optical communication. This optical fiber is a cable for optical communication, with a transmission side optical coupling module at one end and a reception side optical coupling module at the other end. Removably connected. The transmitting side optical coupling module is mounted on the casing as a light emitting element, for example, a laser diode, and the receiving side optical coupling module is mounted as a light receiving element, for example, a photodiode. A condensing lens is incorporated in the casing of each of the optical coupling modules on the transmission side and the reception side.

  The end portion of the optical fiber in the optical communication cable is usually inserted into a ferrule made of a guide cylinder to constitute a connector. On the other hand, the casing of the optical coupling module includes a sleeve to which a connector is detachably connected and a holder on which a light receiving element such as a photodiode is mounted, and a condensing lens is incorporated in the sleeve. When the connector of the optical communication cable is connected to the sleeve, the end face of the optical fiber comes to a position facing the condenser lens. In order for the light output from the optical fiber to be efficiently received by the light receiving element, the condenser lens is mounted, and the sleeve into which the connector is inserted and the holder mounted with the light receiving element must be accurately aligned. .

Here, it is desirable that the total amount of light irradiated from the optical fiber be taken into the light receiving element. Therefore, if the size of the projection pattern of the output light from the optical fiber onto the light receiving surface of the light receiving element is made smaller, the entire light quantity is received by the light receiving element. Such usage is disclosed in FIG. 4 of Patent Document 1, for example.
JP-A-6-273638

  By the way, the optical communication cable is provided in the receiving unit of the communication device and is detachably connected to the receiving-side optical coupling module including the light receiving element. Therefore, the connector of the optical communication cable is connected to the optical coupling module. When done, the optical fiber and the light receiving element must be accurately aligned. For this reason, after the optical coupling module is manufactured, an inspection is performed as to whether or not the optical fiber provided in the connector and the light receiving element are aligned. In general, whether or not an optical fiber and a light receiving element are aligned is inspected by actually connecting a connector of an optical communication cable and measuring the amount of light received by the light receiving element. become.

  From the above, when the alignment measurement with the optical communication cable performed after the manufacture of the optical coupling module is performed, the optical axis center of the optical fiber is determined even if it is determined to be an acceptable product. The center of the light receiving element is not always exactly coincident. That is, even if the spot diameter of the light emitted from the optical fiber is slightly deviated from the light receiving surface of the light receiving element, the amount of light received by the light receiving element hardly changes. The amount of light received by the light receiving element at the time of alignment is set in advance as a reference level. Even if the optical fiber and the light receiving element are slightly misaligned, it is determined that the optical communication cable and the light receiving element are aligned. There is a possibility that.

  In recent years, information has been exchanged between communication terminals and devices such as personal computers and television receivers, such as optical communication cables for short-distance transmission, such as an optical LAN (Local Area Network) as an optical communication system. In this case, the connection of the connector to the optical coupling module is also performed on the user side. Generally, when manufacturing or assembling parts, variations in slight dimensions may occur due to their accuracy, and variations may also occur in the fitted state. Therefore, even if it is determined to be accurate at the time of the alignment measurement described above, when the connector of the optical communication cable is connected to the optical coupling module containing the measurement error, the position is shifted in the direction in which this error increases. As a result, part of the light from the optical fiber may be detached from the light receiving element, resulting in a decrease in the amount of light received by the light receiving element, resulting in a disadvantage that the signal S / N ratio is reduced. It will be.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a sleeve to which a connector of an optical communication cable is detachably connected in an optical coupling module, and a holder to which a light receiving element is attached. The purpose of this is to make it possible to carry out the alignment measurement with extremely high accuracy.

  In order to achieve the above-mentioned object, the present invention connects a holder incorporating a light receiving element, a condensing lens, and a connector for an optical communication cable through which an optical fiber for transmitting an optical signal is inserted, so that the connector is detachable. The optical coupling module for optical communication comprising a sleeve is fixed in a state in which the holder and the sleeve are aligned, the spot diameter being sufficiently wider than the light receiving surface of the light receiving element, and the center of the optical axis An alignment measuring light irradiation device equipped with an optical fiber that irradiates light having a distribution in which the intensity of light decreases as it goes from the periphery to the peripheral portion is connected to the sleeve, and the maximum amount of light is received by the light receiving element. Adjusting the relative positional relationship between the sleeve and the holder, and connecting and fixing the sleeve and the holder at the position where the maximum light receiving amount is obtained. It is an its features.

  Here, the optical fiber used for the alignment measurement light irradiation device is light having a distribution in which the intensity of light continuously decreases from the center of the optical axis toward the periphery on the light receiving surface of the light receiving element, that is, It is desirable to have a characteristic that substantially has a Gaussian distribution. Therefore, a graded index type multimode optical fiber having a larger diameter than the optical fiber provided in the connector connected to the optical coupling module or the same type of fiber is preferably used.

  Further, as an invention relating to a measuring light irradiation device for alignment alignment of an optical coupling module, an optical communication cable in which a holder incorporating a light receiving element and a condensing lens are mounted and an optical fiber for transmitting an optical signal is inserted An optical measuring module for optical communication comprising a sleeve to which a connector of the connector is detachably connected is used for aligning the holder and the sleeve. A connecting portion that is detachably connected to the sleeve in place of the connector, and is inserted into the connecting portion so as to be larger than the optical signal transmission optical fiber. It is composed of a graded index fiber having a diameter or a fiber of the same type as the optical signal transmission optical fiber. That.

  In the present invention, when the connector of the optical communication cable is connected, there is an effect that the optical fiber is connected to the light receiving element with extremely high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, for example, a configuration in which an optical communication cable is detachably connected to an optical coupling connector provided in a receiving unit of a communication device equipped in a personal computer or the like is shown.

  1 and 2, reference numeral 1 denotes a communication device equipped with an optical coupling module 2, and an optical communication cable 3 is detachably connected to the optical coupling module 2 of the communication device 1. FIG. 1 shows a state where the optical communication cable 3 is connected to the optical coupling module 2, and FIG. 2 shows a separated state. The optical coupling module 2 includes a sleeve 5 that is fixedly provided on the connection member 4 and a holder 6 that is connected to the sleeve 5. The sleeve 5 is formed with an insertion passage 7 into which a ferrule 23 provided in the connector 20 of the optical communication cable 3 to be described later is inserted and removed, and an annular positioning wall 8 is formed in the middle of the insertion passage 7. Yes. A condensing lens 9 is attached at a position ahead of the positioning wall 8, that is, at a position inside the communication device 1.

  A photodiode 10 is mounted on the holder 6 as a light receiving element that receives an optical signal and converts it into an electrical signal, and is fixed by, for example, an adhesive. Therefore, the holder 6 positions the light receiving surface 10a of the photodiode 10 at a predetermined position and constitutes a connecting portion with the sleeve 5. A plurality of contact pins 11 extend to the photodiode 10, and these contact pins 11 are connected to a circuit board (not shown) built in the communication device 1.

  Next, the optical communication cable 3 is provided with a connector 20 connected to the end of the flexible cable 21. The connector 20 includes a connector main body 22, a ferrule 23 fixed to the connector main body 22, and an optical fiber 24 inserted into the ferrule 23. The optical fiber 24 extends from the flexible cable 21 into the connector 20, and its emission end 24 a faces the tip of the ferrule 23.

  An annular recess 25 is formed between the connector main body 22 and the ferrule 23 in the connector 20. When the connector 20 is connected to the optical coupling module 2, the sleeve 5 has a predetermined length in the recess 25. At this time, the ferrule 23 comes into contact with the positioning wall 8 provided on the sleeve 5. Therefore, the insertion portion of the connector 20 into the sleeve 5 is the ferrule 23, and the end face and the outer diameter of the ferrule 23 match the dimensions of the positioning wall 8 and the insertion path 7 in the sleeve 5, thereby the connector 20. Is connected to the optical coupling module 2, the optical fiber 24 has a predetermined positional relationship with the photodiode 10. In the figure, reference numeral 12 denotes a clamp provided on the connection member 4. When the ferrule 23 of the connector 20 is inserted into the sleeve 5 and the tip of the ferrule 23 abuts against the positioning wall 8, the connector The clamp claw 12a of the clamp portion 12 is engaged with the stepped portion 22a formed in the main body 22, whereby the connector 20 is fixed while being connected to the optical coupling module 2.

  Thus, although the light output from the output end 24 a of the optical fiber 24 diverges, it is condensed by the condenser lens 9 mounted in the sleeve 5 in the optical coupling module 2 and is incident on the photodiode 10. The photodiode 10 is converted into an electrical signal (voltage or current) corresponding to the amount of received light. In this case, in order to improve the S / N ratio of the signal, it is necessary to increase the amount of light emitted from the output end 24a of the optical fiber 24 to the light receiving surface 10a of the photodiode 10 via the condenser lens 9. There is. Therefore, as shown in FIG. 3A, when the output light from the optical fiber 24 is projected onto the light receiving surface 10a of the photodiode 10, the spot diameter of the output light (indicated by hatching in the figure). The range is generally the same as or smaller than the light receiving surface 10a.

  The sleeve 5 and the holder 6 constituting the optical coupling module 2 are formed separately and then connected and fixed by means such as welding. From the above, it is necessary to align the sleeve 5 and the holder 6 when they are connected. In performing this alignment, the connector 20 of the optical communication cable 3 is connected to the sleeve 5, and the alignment measurement is performed from the optical fiber 24 in a state where the sleeve 5 is temporarily fixed to the holder 6 incorporating the photodiode 10. The light for use is emitted. Then, the amount of light received by the photodiode 10 is measured, and when the output of the photodiode 10 reaches a maximum, the focusing lens 9 and the connector 20 constituting the sleeve 5 are positioned in a connected state. Are fixed to the photodiode 10 in this state, the sleeve 5 and the holder 6 are fixed by welding means or the like. Thereby, in the optical coupling module 2, when the connector 20 is connected to the sleeve 5, the optical axis from the optical fiber 24 to the photodiode 10 is adjusted.

  By the way, as described above, since the spot diameter of the output light from the optical fiber 24 is smaller than the light receiving surface 10a, even if the total amount of the output light from the optical fiber 24 is received by the photodiode 10, The optical axes from the optical fiber 24 to the photodiode 10 do not necessarily coincide exactly. That is, as shown in FIG. 3A, when the center of the light receiving surface 10a of the photodiode 10 is O1, the center of the spot p in the output light of the optical fiber 24 as shown by the solid line in FIG. Is coincident with the center of the light receiving surface 10a of the photodiode 10, and as shown by the phantom line, the center of the spot diameter in the output light of the optical fiber 24 is O2, and the center O1 of the light receiving surface 10a. Even if it is decentered by Δs, the amount of light received at the light receiving surface 10a of the photodiode 10 does not change. That is, even if the light intensity distribution is d1 indicated by a solid line or the virtual line d2, the amount of light received on the light receiving surface 10a does not change, so it is determined that alignment has been performed. If the optical coupling module 2 is incorporated into the communication device 1 while the connector 20 of the optical communication cable 3 is connected, this eccentricity of Δs will not be a problem.

  However, the optical coupling module 2 is incorporated in the communication device 1 in advance, but the optical communication cable 3 is attached to and detached from the optical coupling module 2. Therefore, when the connector 20 of the optical communication cable 3 is actually connected to the optical coupling module 2, the above-described eccentricity Δs further increases due to a dimensional error between the connector 20 and the optical coupling module 2. Specifically, as shown in FIG. 3A, when the center of the light spot p is further displaced to the right, a large loss occurs in the amount of light received by the optical coupling module 2.

  From the above, at the time of the alignment measurement described above, the optical measurement cable 3 is used as shown in FIG. 4 without using the optical communication cable 3. This alignment measuring light irradiation device 30 has the same outer shape as the connector 20, that is, has a connector main body 32 having the same shape as the connector main body 22 and a ferrule 33 having the same shape as the ferrule 23. The ferrule 23 and the ferrule 33 which are portions where the connector 20 is inserted into the sleeve 5 have the same outer diameter. The shapes of the connector body 32 and the ferrule 23 are finished with high accuracy for adjustment. Therefore, the alignment of the insertion path 7 and the positioning wall 8 of the sleeve 5 in the optical coupling module 2 is performed with extremely high accuracy. The optical fiber 34 inserted into the ferrule 33 has a larger diameter than the optical fiber 24 of the connector 20 and a graded index type multimode optical fiber is used. Furthermore, a flexible cable 31 for guiding light from the light source is connected to the alignment measuring light irradiation device 30.

  Next, a method of performing alignment between the sleeve 5 incorporating the condenser lens 9 and the holder 5 equipped with the photodiode 10 using the alignment measuring light irradiation device 30 having the above configuration will be described. That is, as apparent from FIG. 4, the sleeve 5 is held by the first clamp member 40 and the holder 6 is held by the second clamp member 41 so that the sleeve 5 and the holder 6 are brought into contact with each other. At this time, the alignment measuring light irradiation device 30 is connected to the sleeve 5.

  As shown in FIG. 3B, the pattern of light emitted from the optical fiber 34 in the alignment measurement light irradiation device 30 has a spot diameter (sufficiently large on the light receiving surface 10a of the photodiode 10 than the light receiving surface 10a). (The range indicated by hatching in the figure). The desired spot radius is about 1.2 to 1.5 times the radius of the light receiving surface 10a. The optical fiber 34 is a graded index type multimode optical fiber. Therefore, the light quantity distribution on the light receiving surface 10a is such that the light quantity gradually decreases from the center position of the optical axis of the optical fiber 34 toward the periphery, and substantially has a Gaussian distribution or a distribution characteristic close thereto. ing.

  As shown in FIG. 3B, when the optical fiber 34 of the alignment measurement light irradiation device 30 and the photodiode 10 are accurately aligned, that is, the center of the light receiving surface 10a of the photodiode 10 and the optical fiber. When the center of the spot in the output light 34 coincides with O1, the pattern P1 indicated by the solid line in the figure is obtained, and the light intensity distribution at that time is as indicated by the solid line D1 in the figure. When the spot from the optical fiber 34 is shifted from the center O1 of the light receiving surface 10a of the photodiode 10 to O2, that is, when the pattern P2 indicated by the phantom line in the figure is reached, the light quantity distribution is also as indicated by the phantom line D2. Accordingly, the amount of light received by the light receiving surface 10a of the photodiode 10 is reduced. In FIG. 3A, the amount of light received by the photodiode 10 does not change even when the optical fiber 24 has an eccentricity Δs, whereas in FIG. 3B, the distance between the light receiving surface 10a of the photodiode 10 is not changed. If there is an eccentricity of Δs, the amount of received light will decrease, resulting in a large light amount difference. Even if there is a slight eccentricity, this eccentricity can be detected as a difference in the amount of received light of the photodiode 10.

  Thus, the sleeve 5 held by the first clamp member 40 and the holder 6 held by the second clamp member 41 are relatively moved so that the light receiving amount of the photodiode 10 is maximized. At that time, the sleeve 5 and the holder 6 are fixed at that position by means such as welding. The condensing lens 9 is incorporated in a predetermined position of the sleeve 5 in advance.

  As described above, in the optical coupling module 2, the insertion path 7 and the positioning wall 8 of the sleeve 5 that are positioned in the state where the connector 20 of the optical communication cable 3 is mounted, the condenser lens 9, and the photodiode mounted on the holder 6. This means that alignment with 10 is extremely accurate. Therefore, when the optical coupling cable 2 is connected to the optical coupling module 2 by attaching the optical coupling module 2 to the communication device 1 together with the connection member 4, output light from the optical fiber 24 is output by the optical coupling module 2. The light receiving surface 10a of the photodiode 10 can be effectively received.

  As a result, the optical coupling module 2 mounted on the communication device 1 such as a personal computer or a television receiver becomes extremely high quality, and the S / N ratio of the communication signal is increased.

It is sectional drawing of the state which connected the optical coupling module of the communication terminal which shows one Embodiment in this invention, and the receiving side connector of the cable for optical communication. It is sectional drawing of the state which isolate | separated the optical coupling module and receiving side connector in FIG. It is a principle explanatory view about alignment of an optical coupling module. It is structure explanatory drawing which shows the state which is performing alignment of the optical coupling module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication apparatus 2 Optical coupling module 3 Optical communication cable 5 Sleeve 6 Holder 7 Insertion path 8 Positioning wall 9 Condensing lens 10 Photodiode 10a Light-receiving surface 20 Connector 22 Connector main body 23 Ferrule 24 Optical fiber 30 Measurement light irradiation device for alignment 32 Connector Body 33 Ferrule 34 Optical fiber

Claims (6)

An optical communication optical coupling module comprising a holder incorporating a light receiving element and a sleeve to which a connector of an optical communication cable through which an optical fiber for optical signal transmission is inserted is detachably connected. In a state where the holder and the sleeve are aligned,
Measurement light irradiation for alignment equipped with an optical fiber that irradiates light having a spot diameter sufficiently wider than the light receiving surface of the light receiving element and having a distribution in which the intensity of light decreases from the center of the optical axis toward the periphery. Connect the device to the sleeve;
Adjusting the relative positional relationship between the sleeve and the holder so that the maximum amount of light by the light receiving element is received;
A method of aligning an optical coupling module, wherein the sleeve and the holder are connected and fixed at a position where the maximum amount of light is received. 2. The light according to claim 1, wherein a radius of a spot of an optical fiber provided in the alignment measuring light irradiation device is 1.2 times or more and 1.5 times or less of a radius of a light receiving surface of the optical element. The alignment method of the coupling module. 2. The alignment method for an optical coupling module according to claim 1, wherein the optical fiber provided in the alignment measuring light irradiation device is a graded index fiber having a larger diameter than the optical fiber for transmitting optical signals. The alignment of the optical coupling module according to any one of claims 1 to 3, wherein the optical fiber for transmitting the optical signal and the optical fiber provided in the measurement light irradiation device for alignment are the same type of optical fiber. Method. An optical communication optical coupling module comprising a holder incorporating a light receiving element and a sleeve to which a connector of an optical communication cable through which an optical fiber for optical signal transmission is inserted is detachably connected. A measuring light irradiation device for alignment used for aligning the holder and the sleeve,
A connecting portion having the same outer diameter as the insertion portion of the connector into the sleeve, and connected to the sleeve in a detachable manner instead of the connector;
An optical coupling characterized in that it is inserted into the connecting portion and is composed of a graded index fiber having a diameter larger than that of the optical fiber for optical signal transmission, or an optical fiber of the same type as the optical fiber for optical transmission. Measuring light irradiation device for module alignment. An optical coupling module in which a sleeve and a holder are aligned by the method according to any one of claims 1 to 4 and incorporated in a receiving unit of a communication device.

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