JP4409303B2 - Optical receptacle and optical module using the same - Google Patents

Description

The present invention relates to an optical receptacle used for an optical communication module and the like and an optical module using the same.

  An optical module for converting an optical signal into an electric signal has a structure in which an optical element such as a semiconductor laser or a photodiode is housed in a case, and the optical signal is introduced into or derived from an optical fiber via a lens or the like. It has become. FIG. 3 shows an example of such an optical module in which a connector is connected. The receptacle-type optical module shown in FIG. 3 has an optical element unit 21 connected to the rear end surface of the optical receptacle 9 and a front end surface connected to the front end surface of the plug ferrule 7.

  The optical receptacle 9 has a through hole 40 formed at the center of the bottom of a bottomed cup-shaped holder 4 formed by cutting or injection molding a stainless steel base material, and the optical fiber 2 is bonded and held at the center of the through hole 40. The rear end of the ceramic fiber stub 1 is press-fitted and held. Then, the end of the fiber stub 1 is fitted through the opening on one side of the sleeve 3, and a cylindrical shell (case) 5 covering the sleeve 3 exposed from the holder 4 is attached to the holder 4 to prevent the sleeve 3 from coming off. The structure is press-fitted into the side wall surface.

  Here, in an optical receptacle that requires high-efficiency optical coupling to a single-mode optical fiber, even if the plug ferrule 7 having the optical fiber 8 bonded and held at the center is repeatedly attached to and detached from the sleeve 3, it is highly accurate. Since positioning is required, high-precision machining is possible as the material of the sleeve 3, and ceramic having excellent wear resistance is often used.

 By the way, in recent years, with the spread of the Internet and the like, optical transmission has become common in data communication, and the optical communication transceiver that is the key device can simultaneously realize high speed, downsizing, and low cost. It has been demanded.

 However, if the size is reduced as it is, the insertion length of the plug ferrule 7 and the insertion length of the fiber stub 1 are shortened, so that the holding force of the sleeve 3 in the optical receptacle is reduced, and the plug ferrule 7 is There is a problem that the position of the fiber 8 in the plug ferrule 7 is shifted due to a lateral load due to its own weight or tension of the optical fiber 8 that is fixed, resulting in a decrease in light output or inability to obtain attachment / detachment reproducibility. Had occurred.

Therefore, in order to reinforce the holding power of the optical receptacle, the entire length of the fiber stub 1 is fitted into the sleeve 3 as shown in FIG. 4, and is pressed into the through hole of the holder 4 at the position of the fitted sleeve 3. 5 by press-fitting the holder 4 into the opening on the rear end side of the shell 5 so that the opening on the rear end side of the shell 4 holds the sleeve 3 and the fiber stub 1 through the holder 4. Also, a technique for reducing the size of the receptacle by holding it at a common position of the holder 4 (see Patent Document 1), and a surface of the holder 4 holding the fiber stub 1 in the through hole as shown in FIG. Since the fiber stub 1 is held only by the holder 4 by providing a stepped portion or the like, there has been proposed a structure that can be formed in a small size and stabilizes the gripping of the sleeve 3 (see Patent Document 2).
Japanese Patent Laid-Open No. 10-332988 Japanese Unexamined Patent Publication No. 2002-350693

 However, in the case of an optical receptacle having a structure in which the fiber stub 1 is held at a common position between the sleeve 3 and the holder 4 as shown in FIG. 4 of the conventional optical receptacle, the plug ferrule 7 has an optical loss compared to the fiber stub 1. In order to connect them without pressure, it is necessary to make the pressure input able to withstand the continuous load or the momentary load at the time of attachment / detachment. Since it is deformed or destroyed, it is necessary to process the diameter of the opening on the rear end side of the sleeve 3, the holder 4 and the shell 5 holding the fiber stub 1 with high accuracy.

  That is, when the sleeve 5 is brought into close contact with the inner diameter of the shell 5 to limit the inclination by making the inner diameter of the shell 5 equal to or smaller than that of the sleeve 3, the through hole 40 into which the fiber stub 1 of the holder 4 is inserted The outer shape into which the shell 5 is fitted, or the coaxiality of the through hole 40, the inner diameter and outer shape of the sleeve 3, the inner diameter of the shell 5 and the outer shaft, the inner diameter of the shell 5 and the inner diameter of the holder 4 and the sleeve 3 of the shell 5 Not only does the amount of eccentricity of the fitting inner diameters be processed with high accuracy, but the center of the outer shape of the fiber stub 1 and the inner diameter center of the shell 5 need to be aligned with high accuracy and without inclination, which not only increases the part cost. There is a problem that the yield is poor.

  Further, when a lateral load is applied to the plug ferrule 7, the insertion end side of the sleeve 3 may spread, and the holding side of the fiber stub 1 is held at the same position. Had the problem of increasing loss.

  Even in the structure in which the holder 4 side holds the end portion of the sleeve 3 as shown in FIG. 5, the insertion end side of the sleeve 3 spreads due to the lateral load on the plug ferrule 7, and the optical fiber is likely to be displaced and the loss increases. There was a problem. Further, the shell 5 itself has a problem that the position held by the excessive insertion and removal of the plug ferrule 7 is not stable, and the sleeve 3 cannot be protected when it is detached.

In view of the above problems, the optical receptacle according to the present invention includes a fiber stub in which an optical fiber is fixed at the center of the ferrule, a holder that holds the rear end of the fiber stub, and one side that holds the tip of the fiber stub. with a second side and the sleeve that holds the plug ferrule that will be connected to the distal end face of the fiber stub, optical receptacle comprising a casing the rear end portion with housing the sleeve is held before Symbol holder, said case Has a flange portion on the outer peripheral surface of the rear end portion, the rear end surface of the flange portion is in contact with the holder, and the front end surface of the flange portion is fitted to the holder It is characterized by being held in contact with the gripping member.

To form a pre-Symbol holder bottomed cup shape, between the flange portion of the case is brought into contact with the bottom surface of the holder, the side wall inner surface and the front SL case outer circumferential surface of the front Stories holder pre Symbol gripping member It is characterized by having been arranged in.

The holder is formed in a cylindrical shape, the gripping member is formed in a cylindrical shape, and a protrusion protruding from the inner wall of the cylinder is formed at one end, and the inner peripheral surface of the gripping member and the outer peripheral surface of the side wall of the holder are fitted together And the holder and the protrusion are in contact with the flange.

Before SL case, characterized in that the plug ferrule into the sleeve is provided with an inner diameter having a clearance relative to the outer diameter of the sleeve when inserted.

  And the optical module of this invention attaches the optical case which accommodated the optical element to the rear-end side of the above-mentioned optical receptacle.

According to the optical receptacle of the present invention, the case has a flange portion on the outer peripheral surface of the rear end portion, and the rear end surface of the flange portion is in contact with the holder, and the front end side surface of the flange portion is since it was held in contact with the fitted gripping member to the holder, it is suppressed by the case held a motion according to a further extent and inclination of the sleeve at the time of applying a lateral load by the gripping member and the holder In addition, since the rear end of the fiber stub is fixed with a holder, a stable connection with a plug ferrule can be realized, and an optical receptacle with excellent lateral load characteristics and an optical module using the same are provided. it can. Accordingly, it is possible to provide an optical receptacle and an optical module that can obtain a sufficient gripping force even if the size is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the member of the same structure as a prior art, it demonstrates using the same code | symbol. FIG. 1 and FIG. 2 are central sectional views for illustrating an embodiment of an optical receptacle of the present invention.

  As shown in FIG. 1, the optical receptacle of the present invention includes a fiber stub 1, a holder 4 for fixing the rear end of the fiber stub 1, one side holding the tip of the fiber stub 1, and the other side of the fiber stub 1. And a shell 5 (case) that is fixed to the holder 4 in a state in which the sleeve 3 is accommodated.

  A feature of the present invention is that the outer peripheral surface of the distal end portion of the fiber stub 1 directly or indirectly from the holder 4 has a gripping member 6 that is gripped by the shell 5 via the sleeve 3.

  The fiber stub 1 has a fiber through hole 1b formed in the center of a ferrule 1a made of a ceramic material such as zirconia or alumina, and an optical fiber 2 made of quartz glass or the like is inserted into the fiber through hole 1b and bonded and fixed. Obtained. The front end surface of the fiber stub 1 is polished into a spherical shape so that the connection with the plug ferrule 7 with the front end surface formed into a spherical shape can be reliably performed. Further, the rear end surface is cut into an inclined surface, and the return light of the laser light when assembled as an optical module as described later is prevented from returning directly to the laser element.

  The holder 4 is formed in a cup shape with a bottom, and a through hole 40 is formed in the center of the bottom surface, and the rear end side of the fiber stub 1 is press-fitted and held in the through hole 40. As the material, a stainless steel material having excellent corrosion resistance and weldability such as SUS304 is used, but a weldable material such as iron or nickel may be used.

  As the sleeve 3, a split sleeve obtained by slitting a cylinder made of phosphor bronze, a ceramic material, or the like into the entire length is used.

  The shell 5 is formed in a cylindrical shape, has an inner diameter that is about 1 to 20 μm larger than the outer diameter of the sleeve 3 spread by the plug ferrule 7 inserted from the other side of the sleeve 3, and is a metal excellent in rust prevention as a material. The sleeve 3 is housed in its entirety. And the collar part 50 is formed in the outer peripheral part of the rear-end side of the shell 5, and it is set as the dimension which the collar part 50 can enter in the holder 4. FIG.

  The gripping member 6 is formed in a ring shape, and a metal, resin, or the like excellent in rust prevention is used. The gripping member 6 is fitted to the holder 4 and is disposed with a predetermined clearance between the inner periphery of the side wall of the holder 4 and the outer periphery of the shell 5. In the state where the plug ferrule 7 is inserted, The outer peripheral surface of the distal end portion of the fiber stub 1 is configured to be indirectly held by the shell 5 via the sleeve 3.

  Accordingly, the expansion of the sleeve 3 at the time of insertion of the plug ferrule 7 is not limited, and there is room for expansion at the time of insertion, and the inclination after the insertion of the plug ferrule 7 is effectively limited by the gripping member 6. The optical connection loss occurs only at a small level just by tilting slightly about the optical fiber ends of both the plug ferrule 7 and the fiber stub 1 to which the optical connection is made.

  Further, the gripping member 6 is engaged with a step region R formed by the outer peripheral surface of the shell 5 and the flange portion 50. As a result, even when the shell 5 is fixed to the holder 4 with an adhesive, the shell 5 is difficult to be removed even if the adhesive is deteriorated by adopting a structure in which the step region R of the shell 5 is engaged. By tilting the bottom surface of the portion 50 against the holder 4, the tilt can be limited.

The structure of the gripping member 6 used in the present invention is not limited to the ring-shaped structure described above. For example, as shown in FIG. 2, the holder 4 is press-fitted into the cylindrical gripping member 6. The outer peripheral surface of the distal end portion of the fiber stub 1 may be configured to be directly held by the shell 5 via the sleeve 3. At this time, the inner diameter of the gripping member 6 is provided with a clearance that does not restrain the shell 5 before the plug ferrule 7 is inserted, and the holder 4 and the shell 5 can be fixed at a free position within the clearance. After the plug ferrule 7 is inserted, it is directly gripped by the shell 5 via the sleeve 3 as described above.
4 and 5 of the conventional structure, when trying to limit the inclination of the sleeve 3 only by making the inner diameter of the shell 5 equal to or smaller than the outer diameter of the sleeve 3, the fiber stub 1 of the holder 4 is inserted. Of the through hole 40 and the shell 5 to be fitted, or the coaxiality of the through hole 40, the coaxiality of the inner diameter and the outer shape of the sleeve 3, the inner diameter to fit the holder 4 of the shell 5, and the inner diameter to fit the sleeve 3 of the shell 5 In addition to processing all eccentricity with high accuracy, it is necessary to match the outer center of the fiber stub 1 and the inner diameter center of the shell 5 with high accuracy and without tilting. The rear end of the fiber stub 1 is fixed by the through hole 40 of the holder 4, and the gripping member 6 is held by the shell 5 directly or indirectly from the holder 4 via the sleeve 3. For, made possible because the deterioration of the insertion loss due to the inclination of the plug ferrule 1 without machining such high accuracy can be easily prevented.

As a desirable configuration, the fiber stub 1 and the sleeve 3 are formed of zirconia ceramics. In particular, the ceramic material contains ZrO ₂ as a main component, and contains at least one of Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like as a stabilizer, and a portion mainly composed of tetragonal crystals. It is preferable to use stabilized zirconia ceramics, and such partially stabilized zirconia ceramics have excellent wear resistance and are appropriately elastically deformed. Therefore, the plug ferrule 7 and the fiber stub 1 are used by utilizing elasticity. It is also advantageous when fixing by press-fitting like the holding sleeve 3 or the fiber stub 1.

  As a ceramic processing method, for example, when forming from zirconia ceramics, for example, a cylindrical or rectangular parallelepiped shaped body is obtained in advance by a predetermined molding method such as injection molding, press molding, extrusion molding, etc. Baking is performed at 1300 to 1500 ° C., and cutting or polishing is performed to a predetermined dimension. Note that a predetermined shape may be formed in advance on the formed body by cutting or the like, and then fired. In addition, the surface roughness is desirably an arithmetic average roughness (Ra) of 0.2 μm or less in consideration of insertability. The end surface on the plug ferrule side of the fiber stub 1 is processed into a curved surface having a curvature radius of about 5 to 30 mm in order to reduce connection loss with the optical connector. Further, the end face on the optical element side is mirror-polished to an inclined surface of about 4 to 10 ° in order to prevent the reflected light from being reflected by the end face of the optical fiber and returning to the optical element.

  In the structure using the fiber stub 4, the rear end face is obliquely polished in order to prevent reflected return light as described above, which is effective particularly when an optical element that is weak against reflection is used.

  In the press-fitting of the fiber stub 1 and the holder 4, not only the pressure input is set high in order to obtain a holding force with sufficient margin against a continuous load from the plug ferrule 7 or an instantaneous load. In order to fit with the shell 5 with high accuracy, it is necessary to be careful not to cause an inclination by press-fitting.

  In the sleeve 3, when the plug ferrule 7 is inserted and inserted so that there is no loss due to the difference in refractive index from the air and a load for optically connecting the optical fibers 2 and 8 is obtained, it is appropriate to hold the plug ferrule 7. It is necessary to have a strong holding force.

  As for the shell 5 and the gripping member 6, when a large load is applied to the plug ferrule 7 in the lateral direction, a force acts in a direction to incline the shell 5 directly through the sleeve 3, so that strength and durability are required. In addition, it is desirable to use a metal having excellent rust prevention properties, such as a metal plated with stainless steel or nickel, or a resin having heat resistance and suppressing thermal expansion as much as possible from the viewpoint of reliability. Further, the sleeve 3 itself is not fixed by the shell 5, and the inclination of the plug ferrule 7 is limited by setting the inner diameter of the shell 5 to have a clearance of 20 μm or less when the plug ferrule 7 is inserted. Thus, the receptacle ferrule 7 has a small variation in holding force with respect to the plug ferrule 7, and the plug ferrule 7 has a good detachability.

  As described above, in the optical receptacle of the present invention, after the plug ferrule 7 is connected to the optical receptacle, the sleeve 3 is not greatly opened or tilted even when a large load is applied to the plug ferrule 7 in the lateral direction. As a result, there is no significant connection loss. Therefore, as shown in FIG. 6, by attaching an optical case housing the optical element to the rear end side of the optical receptacle in FIG. 1, the lateral load due to the weight or tension of the optical fiber cord compared to the optical receptacle module in FIG. Therefore, it is possible to provide a good optical module with little loss.

  Examples of the present invention will be described.

  First, as an example of the present invention, an optical receptacle shown in FIG. 1 was produced. The optical connector connected to the optical receptacle was an LC connector. The cylindrical ceramic used as the fiber stub 1 was made of zirconia, and a cylindrical ceramic molded body was obtained by extrusion molding, and was baked and hardened in a firing process, followed by cutting.

  The optical fiber 2 is inserted and fixed in the cylindrical ceramic fiber through hole 1b thus obtained, the tip is mirror-polished to a curved surface with a curvature radius of about 10 mm, and the opposite side is emitted from an optical element such as an LD element. In order to prevent the reflected light from being reflected at the tip of the optical fiber and returning to the optical element, the inclined surface of 8 ° was mirror-polished to obtain a fiber stub 1.

  Further, in order to press-fit the fiber stub 1 into the holder 4 made of SUS304 having excellent rust prevention and weldability, it was press-fitted while confirming a sufficient load with a hand press with a pressure sensor (not shown). At this time, the press-fitting strength in the vicinity of the fixed position of this sample was about 120N.

  Accordingly, since the fiber stub 1 does not move if the load is less than that, the fiber stub 1 is sufficiently strong against the pressing force by the plug ferrule 7 and the impact at the time of attachment / detachment.

  Next, a split sleeve is used as the sleeve 3, which is made of zirconia ceramics and has a total length of 5 mm, and the fiber stub 1 is inserted into the through hole 40 of the holder 4. After the fiber stub 1 is abutted to the end surface of the holder 4, the sleeve 3 is fitted into a cylindrical shell 5 formed in a predetermined shape as shown in the figure having a flange 50 made of SUS304 having excellent rust prevention properties. The inner diameter of the shell 5 at this time was set to have a clearance of 4 μm with respect to the maximum outer diameter of the sleeve 3 when the plug ferrule 7 was inserted. Thereafter, the flange portion 50 of the shell 5 is abutted to the bottom surface portion of the holder 4, and thereafter, the flange portion 50 of the shell 5 is sandwiched and fixed while the gripping member 6 of SUS303 having excellent rust prevention properties is press-fitted into the holder 4. As a result, an optical receptacle having a length of 7.5 mm was obtained.

For comparison, the shell 5 has a conventional structure in which the flange portion 50 is not pressed and is press-fitted into the holder 4, and the inner diameter of the shell 5 is 100 μm clearance from the outermost diameter of the sleeve 3 when the plug ferrule 7 is inserted. Other than the above, it was prototyped as an equivalent optical receptacle.

  As a comparative measurement of the lateral load, the receptacles of the present invention and the conventional structure were respectively modularized as shown in FIG. 6 in which an optical case having an LD element on an optical receptacle was aligned and fixed. After a constant light is output from the power source and the plug ferrule 7 is inserted and connected to the connector, the light output is measured by a light output measuring instrument. And it implemented by the method of measuring the optical output with respect to a lateral load on the basis of the optical output before applying a lateral load.

  In this experiment method, the split sleeve is applied to the shell side and the fiber stub side is lifted by 0.2 mm with the plug ferrule 7 inserted in the optical receptacle of the present invention and the optical receptacle of the conventional structure without the gripping member 6 FIG. 7 shows the result of comparative measurement of the lateral load with Nishimono.

  As shown in FIG. 7, it was confirmed that the present invention is superior to this in measuring the lateral load, and is small and superior to the characteristics of the lateral load. In particular, it can be understood that even if the lateral load increases, the insertion loss does not deteriorate and can be stabilized.

The present invention is applicable not only to optical communication modules and the like, but also to optical modules for sensor applications.

It is sectional drawing which shows one Embodiment of the optical receptacle of this invention. It is sectional drawing which shows one Embodiment of the optical receptacle of this invention. It is sectional drawing which shows one Embodiment of the conventional optical receptacle. It is sectional drawing which shows one Embodiment of the conventional optical receptacle module. It is sectional drawing which shows one Embodiment of the conventional optical receptacle. It is sectional drawing explaining the measuring method of the connection loss with respect to a lateral load. It is a graph which shows the connection loss with respect to the lateral load of this invention and a prior art example.

Explanation of symbols

1: fiber stub 2: optical fiber 3: sleeve 4: holder 5: shell 6: gripping member 7: plug ferrule
8: Optical fiber 9: Optical receptacle 21: Optical unit 40: Through hole

Claims (5)

A fiber stub with an optical fiber fixed at the center of the ferrule, a holder that holds the rear end of the fiber stub, and a plug that holds one end of the fiber stub and the other side connected to the front end of the fiber stub An optical receptacle comprising a sleeve for holding a ferrule and a case for housing the sleeve and having a rear end held by the holder, the case having a flange on an outer peripheral surface of the rear end And the rear end surface of the collar portion is in contact with the holder, and the surface of the distal end side of the collar portion is in contact with and held by a gripping member fitted in the holder. Light receptacle. The holder is formed in a bottomed cup shape, the flange portion of the case is brought into contact with the bottom surface of the holder, and the gripping member is disposed between the inner peripheral surface of the side wall of the holder and the outer peripheral surface of the case. The optical receptacle according to claim 1. The holder is formed in a cylindrical shape, the gripping member is formed in a cylindrical shape, and a protrusion protruding from the inner wall of the cylinder is formed at one end, and the inner peripheral surface of the gripping member and the outer peripheral surface of the side wall of the holder are fitted together It causes the optical receptacle as claimed in claim 1, characterized in that said holder and said projection portion abuts against the flange portion. The optical receptacle according to claim 1, wherein the case has an inner diameter having a clearance with respect to an outer diameter of the sleeve when the plug ferrule is inserted into the sleeve. . An optical module comprising an optical case housing an optical element attached to a rear end side of the optical receptacle according to claim 1.

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