JP2009205105A - Optical device with optical filter, and optical receptacle and light receiving module, using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device with an optical filter having high reliability and giving a sufficient reflection attenuation amount in a simple configuration, and to provide an optical receptacle and a light-receiving module. <P>SOLUTION: The optical device with the optical filter comprises a ferrule having an inclined part composed of one end face inclined with respect to a direction orthogonal to the axial direction of an inner hole, an optical fiber inserted into the inner hole of the ferrule, and an optical filter which has a filter film that selectively transmits light in a specified wavelength band, and in which the filter film is joined to a surface facing the inclined part of the ferrule so as to clog the inner hole open on the end face of the ferrule. The optical fiber is formed by joining a single mode fiber and a graded index fiber, and the graded index fiber is disposed on the optical filter side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical device used for optical communication, an optical receptacle using the optical device, and a light receiving module.

  A band that selectively transmits only the required optical signal from the transmitted multiplexed signal when only a specific wavelength signal is required in the multiplexed signal when performing optical communication between the transmitting and receiving apparatuses. A path filter (hereinafter also simply referred to as a filter) is required. As an optical component including such a filter, for example, there is an optical component that is configured by attaching a filter to an end face of a connector ferrule with a built-in optical fiber.

  FIG. 8 is a schematic view of a conventional optical connector 100 with a filter. The optical connector ferrule 102 has a cylindrical shape, and the optical fiber 101 is inserted into an optical fiber insertion hole provided at the axial center thereof. The optical fiber 101 is fixed to the connector ferrule 102 by an adhesive, and one end surfaces of the optical connector ferrule 102 and the optical fiber 101 are inclined at a predetermined angle with respect to a plane perpendicular to the axial center. The optical filter 103 is bonded and fixed to the adhesive 104.

  The optical filter 103 is an interference filter in which a dielectric multilayer filter is deposited on one side of a transparent glass substrate. For example, the optical filter 103 transmits an optical signal having a wavelength λ1, but transmits optical signals having wavelengths λ2 and λ3. It has selective transparency to reflect.

When such an optical connector with a filter is used, optical multiplexed signals of wavelengths λ1, λ2, and λ3 propagating through the optical fiber 101 are selectively transmitted by the optical filter 103 that is bonded and fixed to the end face of the connector ferrule 102. Thus, only the optical signal having the wavelength λ1 required by the receiving apparatus side is propagated to the receiving apparatus side.
Japanese Patent Laid-Open No. 2-195306

  However, in the optical connector with an optical filter described above, the light of wavelength λ3 that is blocked from being transmitted is reflected by the filter film, so that the reflected light enters the optical fiber and propagates through the optical fiber as reflected return light. There is a problem that the return loss is reduced. In general, in order to reduce such reflected return light, the optical filter is disposed at a predetermined angle with respect to a plane perpendicular to the optical axis, but the reflected return light is further reflected at the end face of the ferrule, A part of the reflected light is reflected, and such an optical connector with an optical filter has a problem that a sufficient return loss cannot be obtained.

  In particular, when using a general single mode fiber for optical transmission as this optical fiber, there is a problem that sufficient return loss cannot be obtained unless the incident angle of the reflected light to the optical fiber is increased. . On the other hand, when the inclination angle of the optical filter is increased in order to realize this incident angle, reflection at the end face of the ferrule increases, and reflected return light may increase.

  The present invention has been made in view of the above, and an object thereof is to provide an optical device with an optical filter, an optical receptacle, and a highly reliable optical filter capable of obtaining a sufficient return loss with a simple configuration. It is to provide a light receiving module.

  As a result of intensive research in view of the above problems, the inventors have changed the arrangement of the filter film in the optical filter and dramatically reduced the reflected return light by arranging the graded index fiber on the optical filter side. Found that you can.

  Accordingly, a ferrule having an inclined portion whose one end surface is inclined with respect to a direction orthogonal to the axial direction of the inner hole, an optical fiber inserted into the inner hole of the ferrule, and light of a specific wavelength band are selectively transmitted. An optical filter having a filter film, the filter film being bonded to a surface facing the inclined portion of the ferrule so as to close an inner hole opened at one end surface of the ferrule, and the optical fiber is a single A mode fiber and a graded index fiber are joined, and the graded index fiber is arranged on the optical filter side.

  Moreover, the said structure WHEREIN: The end surface of the said ferrule further has a surface which cross | intersects the said inclination part with a predetermined angle, It is characterized by the above-mentioned. With the above configuration, the light emitted from the optical fiber is reflected between the filter film and the surface intersecting the inclined portion at a predetermined angle, and the light proceeds toward the light receiving element. Is prevented.

  Further, in the above configuration, the optical filter is bonded to one end surface of the fiber stub through an optical adhesive having a high light transmittance, and the thermal expansion coefficient of the optical adhesive is the main part of the optical filter. The translucent support and the ferrule are substantially the same as those of the above-mentioned ferrule, or between their thermal expansion coefficients. By setting the thermal expansion coefficient of the optical adhesive as described above, it is possible to reduce the influence of thermal stress on the optical filter film, and to reduce the filter characteristic fluctuation due to temperature change.

  Moreover, the said structure WHEREIN: The said optical fiber is further provided with the coreless fiber joined with the said graded index fiber on the said optical filter side, It is characterized by the above-mentioned.

  An optical receptacle according to the present invention includes any one of the above-described optical devices with a filter, a bottomed cylindrical holder having a fitting hole for holding one end of the ferrule, and a sleeve inserted into the other end of the ferrule. And a cylindrical sleeve case having an accommodation hole for accommodating the sleeve and having one end fixed to the holder.

  Furthermore, a light receiving module according to the present invention is bonded to the above-mentioned optical receptacle, the light-receiving element that receives light via the optical fiber and the optical filter, and the holder of the optical receptacle, and houses the light-receiving element. And a cylindrical body.

  According to the optical device with an optical filter of the present invention, the filter film is disposed on the surface of the optical filter that faces the inclined portion, that is, the surface of the optical filter that faces the ferrule, and the optical fiber is graded on the optical filter side. Since the index fiber is provided, the numerical aperture NA of the optical fiber can be reduced, so that the reflected return light is hardly coupled to the optical fiber. As a result, in the optical device with an optical filter of the present invention, a sufficient return loss can be obtained even if the incident angle of the reflected light to the optical fiber is small, so that reflection at the end face of the ferrule can also be reduced.

  Therefore, according to the present invention, it is possible to provide a highly reliable optical device with an optical filter, an optical receptacle, and a light receiving module that can obtain a sufficient return loss with a simple configuration.

  As shown in FIG. 1, the optical device with an optical filter 1 according to the present invention has an inner hole 21 and an end surface 22, and the end surface 22 has an inclined inclined portion 23, An optical fiber 4 inserted into the hole 21; and an optical filter 6 having a filter film 6b that selectively transmits light in a specific wavelength band and joined to the inclined portion 23 of the ferrule 5. A filter film 6 b is formed on a surface 6 a ′ of the filter 6 facing the inclined portion 23. Further, in the optical device 1 with the optical filter, the optical fiber 4 is formed by joining a single mode fiber (SM fiber) 9 ′ and a graded index fiber (GI fiber) 9 ″, and the GI fiber 9 ″ is the optical filter 6. It is arranged on the side.

  Hereinafter, the optical device with an optical filter 1 according to the present invention will be described in detail with reference to the drawings. However, the embodiment described below exemplifies the present invention, and the present invention is not limited to this. In addition, in each figure, about the common part and member, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

(Embodiment 1)
FIG. 2A is a cross-sectional view of optical device 1 with an optical filter (hereinafter referred to as optical device 1) according to Embodiment 1 of the present invention. The optical device 1 according to the first embodiment of the present invention has a cylindrical ferrule 5 having an inner hole 21 for inserting the optical fiber 4 and an end face 22 having an inclined inclined portion 23, and the ferrule 5. An optical fiber 4 inserted into the inner hole 21, a bandpass filter (hereinafter referred to as an optical filter) 6 joined to the inclined portion 23 of the ferrule 5, and an optical adhesive 7 for joining the optical filter 6, . An optical fiber 4 is inserted into the inner hole of the ferrule 5 and bonded to form a fiber stub. One end surface of the fiber stub (one end surface of the ferrule 5) is formed to be inclined at a predetermined angle with respect to its axis, in other words, a direction perpendicular to the axial direction of the inner hole 21. Therefore, in the first embodiment, both the inclined portion 23 of the ferrule 5 and the end face of the optical fiber 4 are inclined at a predetermined angle. The optical filter 6 is bonded and fixed to the inclined portion 23 of the ferrule 5, that is, one end surface of the fiber stub by an optical adhesive 7. The optical fiber 4 is formed by joining a single mode fiber (SM fiber) 9 ′ and a graded index fiber (GI fiber) 9 ″, and the GI fiber 9 ″ is arranged on the optical filter 6 side.
The filter film 6 b is formed on the surface 6 a ′ of the optical filter 6 that faces the inclined portion 23 of the ferrule 5.

  FIG. 2B is a cross-sectional view showing a configuration of an optical device 100 having a filter film arrangement different from that of the optical device 1. When the filter film 6b is formed on the surface 6a "of the optical filter 6 opposite to the inclined portion 23 of the ferrule 5, it propagates through the core portion 3 of the optical fiber 4 as shown in FIG. Part of the light (light having a specific wavelength blocked from being transmitted) passes through the optical adhesive 7 and the translucent support 6a constituting the main part of the optical filter 6, and then the surface 6a "of the optical filter 6. It is reflected by the filter film 6b formed on the surface. A part of the reflected light is reflected by the inclined portion 23 of the ferrule 5, and then repeatedly reflected between the filter film 6 and the inclined portion 23 of the ferrule 5 on the outer periphery of the optical fiber, and then proceeds to the light receiving element side. The light having a specific wavelength that should be prevented from being transmitted is received by the light receiving element. However, as shown in FIG. 2A, in the optical device 1 according to the present embodiment, the filter film 6 b is formed on the surface 6 a ′ of the optical filter 6 facing the inclined portion 23 of the ferrule 5. Therefore, the light that propagates through the core portion 3 of the optical fiber 4 and is reflected by the filter film 6 b is almost incident on the clad 2 of the optical fiber 4. For this reason, the light incident on the clad 2 is gradually attenuated during back propagation, thereby improving the return loss characteristic of the optical device. Furthermore, in the optical device 1 according to the present embodiment, the optical fiber 4 is formed by joining the SM fiber 9 ′ and the GI fiber 9 ″, and the GI fiber 9 ″ is disposed on the optical filter 6 side. The reflection at the end face of the ferrule can be prevented, and the amount of reflected return light coupled to the core portion 3 can be reduced by the lens effect of the GI fiber lens.

  FIG. 3 shows the return loss with respect to the optical filter incident angle of the optical device 1. ● is for the optical device 1 according to the present embodiment in which the filter film is formed on the surface 6 a ′ of the optical filter 6, and □ is the inclined part of the ferrule of the optical filter 6 This is for the optical device 100 formed on the opposite surface 6a ″. In the optical device 100, when the incident angle with respect to the optical filter is 1.2 ° to 2.5 °, the return loss is 35 dB. However, the optical device 1 according to the present embodiment increases proportionally and can obtain a higher return loss than when a conventional optical device is used. Is in the normal range (greater than 0 ° and 3 ° or less), the reflection attenuation characteristics of the optical device are particularly improved.

  The single mode fiber 9 ′ of the optical fiber 4 includes a core part 3 having a high refractive index and a clad part 2 covering the outer periphery of the core part 3, and optical confinement due to a refractive index difference between the core part 3 and the clad part 2. It is an optical waveguide that transmits light within the core portion 3 by being used. The single mode fiber 9 ′ is made of, for example, cylindrical quartz or the like. The outer diameter of the cladding portion 2 is 125 μm, and the diameter of the core portion 3 is about 10 μm.

  The GI fiber 9 ″ of the optical fiber 4 is an optical fiber having an approximately square refractive index distribution in its axial symmetry, and is also called a refractive index distribution fiber. The GI fiber 9 ″ is a gradient index lens. Since it can be used, it has the function of collimating the light emitted from the single mode fiber 9 ′ in a conical shape. The GI fiber 9 ″ is made of, for example, columnar quartz, the outer diameter of the cladding portion 2 is 125 μm, the diameter of the core portion 3 is about 50 to 120 μm, and the core portion 3 has the above-described refractive index distribution. Then, the GI fiber 9 ″ and the single mode fiber 9 ′ constitute the optical fiber 4 by being bonded by, for example, heat fusion. Such heat fusion bonding can be performed without interposing a material whose refractive index changes at the interface between the single mode fiber 9 ′ and the GI fiber 9 ″, and is preferable from the viewpoint of reducing light loss. Note that the joining of the single mode fiber 9 ′ and the GI fiber 9 ″ is not limited to joining by fusion, and may be joined by, for example, an adhesive.

The ferrule 5 has a function of holding the optical fiber 4 and the optical filter 6. The ferrule 5 has a cylindrical shape, and as a constituent material, a simple substance such as zirconium oxide (zirconia), aluminum oxide (alumina), mullite, silicon nitride, silicon carbide, and aluminum nitride, or these as a main component is included. Examples include ceramics, phosphor bronze, beryllium copper, brass, stainless steel, glass ceramics such as crystallized glass, and plastics such as epoxy and liquid crystal polymer. Ceramics as components) are preferred. Among zirconia-based ceramics, in particular, at least one selected from the group consisting of zirconium oxide (ZrO ₂ ) as a main component and Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like is used as a stabilizer. Partially stable zirconia ceramics (mainly tetragonal crystals) are included as a more preferable material from the viewpoints of wear resistance and elastic deformation.

  In the ferrule 5, the optical fiber 4 is fixed through an adhesive in an inner hole 21 provided in a substantially central portion. Further, the end surface of the ferrule 5 on the GI fiber 9 ″ side is inclined at a predetermined angle with respect to a direction orthogonal to the axial direction of the ferrule 5 (the axial direction of the inner hole), and the inclined portion 23 thereof. The optical filter 6 is bonded and fixed by the optical adhesive 7 so as to close the opening of the inner hole 21.

  The optical filter 6 includes a plate-like, for example, translucent support 6a having a light incident surface 6a ′ and a light emitting surface 6a ″, and the light emitting surface 6a ′ is provided with a filter film 6b. The filter film 6b is a so-called band pass filter having a function of selectively transmitting a specific wavelength region from light including light of a plurality of different wavelength regions.

  The translucent support 6a constituting a part of the optical filter 6 is made of, for example, optical glass (borosilicate glass or white plate glass) or quartz glass, and has a refractive index of about 1.45 to 1.65. It is done. In addition, the size of the translucent support 6a may be equal to or larger than the effective diameter of light, for example, a flat substrate having a size of about 0.5 mm square. The filter film 6b formed on the end face of the optical filter 6 is a multilayer film configured by alternately laminating two or more kinds of dielectrics having different refractive indexes such as silicon dioxide and titanium dioxide. This dielectric multilayer film exhibits wavelength selectivity due to repeated reflection interference between the dielectric films, and its film thickness is set to be a multiple of 1/4 wavelength of the wavelength of light to be reflected. In other words, by multilayering so that a pair of high and low refractive indexes has a ½ wavelength, the phase of light of a specific wavelength is matched in multiple reflection at each dielectric film interface, and is strengthened by interference. By matching, a filter having a wavelength selection system can be obtained. In the optical filter 6, the filter film 6b is formed on the surface of the translucent support 6a. For example, the filter film 6b is deposited on the light incident surface 6a ′ of the translucent support 6a by a method such as vapor deposition or sputtering. Can be easily created. The optical filter 6 is provided with a filter film 6b so as to function as a filter having a light transmission and reflection wavelength range of 0.5 to 100 nm, and the dielectric multilayer film in the filter film 6b is provided. The number of layers is about 100 to 250.

  In the optical filter 6, the light emitting surface 6 a ″ of the translucent support 6 a on which the filter film 6 b is disposed is inclined within a range of ± 3 ° with respect to the direction orthogonal to the axial direction of the inner hole 21 of the ferrule. In addition, when the incident angle is 0 degree, the optical filter 6 is more likely to return the reflected wavelength light directly to the optical fiber 4. It is more preferable to set the angle to be 3 degrees or less other than 0 degrees from the viewpoint of reducing the incident angle dependency and preventing the reflected return light, where the angle is the light exit surface 6a of the translucent support 6a. ′ And the direction perpendicular to the axial direction of the inner hole 21 of the ferrule 5. If the light incident surface and the light emitting surface of the translucent support 6 a are parallel to each other, the light incident surface, or One end surface of the ferrule and the axial direction of the through hole of the ferrule It may be an angle formed with an orthogonal direction.

  The optical adhesive 7 is made of, for example, a translucent epoxy resin, and has a light transmittance of 90% or more, more preferably 95% or more, and still more preferably 99% or more when the thickness is 0.1 mm. Good to have

  As described above, according to the optical device 1 according to Embodiment 1 of the present invention, the surface 6 a ′ of the optical filter 6 facing the inclined portion 23, that is, the surface 6 a ′ of the optical filter 6 facing the ferrule 5. Since the filter film 6b is disposed on the optical fiber 4, the reflected return light is incident on the clad of the optical fiber 4 and gradually attenuates during propagation through the clad, so that the reflection attenuation characteristic can be improved.

(Embodiment 2)
Next, an optical device 1 ′ according to Embodiment 2 of the present invention will be described with reference to FIG. The optical device 1 ′ according to the second embodiment has an end surface of the ferrule 5 in that the end surface 22 of the ferrule 5 is notched and further includes a surface (intersection surface) 24 that intersects the inclined portion 23 at a predetermined angle. 22 is different from the optical device 1 of the first embodiment in which the crossing surface 24 is not provided. About another structure, it is the same as that of the structural member which concerns on Embodiment 1. FIG.

FIG. 4 is a cross-sectional view showing an optical device 1 ′ according to Embodiment 2 of the present invention.
In the optical device 1 ′ according to the second embodiment, the end surface 22 of the cylindrical ferrule 5 further includes a surface (intersection surface) 24 that intersects the inclined portion 23 at a predetermined angle. The intersecting surface 24 is preferably formed so as not to cut the optical fiber 4. In particular, as shown in FIG. 4, if the intersection surface 24 is formed so as to contact the lower end of the optical fiber 4, in other words, the edge of the inner hole 21 on the optical filter 6 side, the reflected return light is transmitted to the intersection surface. Since it becomes easy to reflect in 24, a reflection attenuation characteristic can be improved more. Further, if the intersecting surface 24 is inclined at a angle greater than 0 ° and not more than 10 ° with respect to the direction perpendicular to the axial direction of the ferrule 5, the adhesion strength of the optical filter 6 to the ferrule 5 can be improved while improving the reflection attenuation characteristics. Can be maintained.

The optical filter 6 is bonded and fixed by the optical adhesive 7 in parallel with the inclined portion 23 of the ferrule 5 inclined. A space is formed between the intersecting surface 24 and the filter film 6b of the optical filter 6, and the optical adhesive 7 is also disposed in this space. In this space, the optical adhesive 7 does not necessarily have to be arranged, but from the viewpoint of firmly fixing the optical filter 6 to the ferrule 5, it is better that the optical adhesive 7 is arranged in this space. .
With the above configuration, the light emitted from the optical fiber 4 is reflected between the filter film 6b and the crossing surface 24 of the ferrule cut out as described above, and receives a light receiving element (not shown). ) The progress of light to the side can be further reduced.
Therefore, in the optical device 1 ′ according to the second embodiment, the reflection attenuation characteristics can be further improved as compared with the optical device 1 according to the first embodiment.

(Embodiment 3)
Next, an optical device 1 ″ according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 5 is a sectional view showing an optical device 1 ″ according to Embodiment 3 of the present invention.

In the optical device 1 ″ according to the third embodiment, the coreless fiber 9 ′ ″ is joined to the end of the GI fiber 9 ″ facing the light incident surface 6a ′ of the translucent support 6a. Thus, the configuration of the optical device 1 according to the first embodiment is different.
In the third embodiment, the optical fiber 4 includes a single mode fiber 9 ′, a graded index fiber 9 ″, and a coreless fiber 9 ″ ′ that are joined in this order. It is arranged on the optical filter 6. The coreless fiber 9 ′ ″ is made of quartz having the same diameter as that of the GI fiber 9 ″ having a single refractive index. The coreless fiber 9 ′ ″ is exposed at one end face of the ferrule 5, and the ferrule 5 and the coreless fiber 9 ′ ″ are polished at the same time so as to have a desired end face angle. . By disposing the coreless fiber 9 ′ ″ on the end face side of the ferrule 5 in this way, it becomes possible to polish the end face without changing the length of the GI fiber 9 ″ having a lens effect. Since the length of the fiber 9 ″ can be maintained, it is preferable in terms of ease of design. Here, the coreless fiber 9 ′ ″ has an outer diameter of 125 μm, which is the same as that of the optical fiber, and is bonded by heat fusion as in the case of the GI fiber 9 ″ and the single mode fiber 9 ′.

(Embodiment 4)
An optical receptacle 10 according to Embodiment 4 of the present invention will be described in detail with reference to the drawings. FIG. 6 is a schematic diagram for explaining an optical receptacle 10 according to Embodiment 4 of the present invention.

  As shown in FIG. 6, the optical receptacle 10 according to Embodiment 4 of the present invention includes a fiber stub 14, a bottomed cylindrical holder 11 having a fitting hole for holding one end of the ferrule 5, and the ferrule 5. The sleeve 12 is inserted into the other end, and a cylindrical sleeve case 13 having a storage hole for receiving the sleeve 12 and having one end fixed to the holder 11.

  In the optical receptacle 10 according to the fourth embodiment, the fiber stub 14 includes, for example, a ferrule 5 made of a ceramic material such as zirconia or alumina, and a single mode fiber 9 ′ made of quartz glass or the like in the inner hole 21 of the ferrule 5. Is obtained by inserting and fixing an optical fiber 4 in which a GI fiber 9 ″ made of quartz glass or the like is bonded to one end of the fiber stub, and press-fitting the rear end portion of the fiber stub 14 into a metal holder 11 for fixing. Further, the inner diameter d of the holder 11 where the fiber stub 14 is inserted is made slightly smaller than the outer diameter D of the fiber stub 14. On the other hand, the tip of the fiber stub 14 is inserted into the inner hole of the sleeve 12. A sleeve case 13 for protecting the sleeve 12 is fixed to the holder 11 by press-fitting or bonding. Further, an optical filter 6 as an optical component is bonded and fixed to the rear end portion (GI fiber end) of the fiber stub 14. The rear end portion (GI fiber end) of the fiber stub 14 is an optical element of the fiber stub 14. It is preferable that the inclined surface be inclined at ± 3 ° (excluding 0 °) with respect to the axis, for example, light having a specific wavelength out of light incident from the light emitting element (LED, LD, etc.) via the plug ferrule 18. Is reflected by the optical filter 6, but by using the inclined surface as described above, it is possible to prevent the reflected light from returning to the light emitting element via the plug ferrule 18 again.

  Hereinafter, the effect of the optical receptacle 10 will be described using the light receiving module of the present invention shown in FIG. The optical fiber 4 of the fiber stub 14 and the optical fiber 19 of the plug ferrule 18 are optically connected. Here, it is preferable that the front end surface of the fiber stub 14 and the front end surface of the plug ferrule 18 are round surfaces (for example, a curvature radius of 5 to 30 mm). By using the round surface in this way, connection loss can be reduced when the optical fiber 19 and the plug ferrule 18 are connected.

  The sleeve 12 has a through-hole into which the fiber stub 14 and the plug ferrule 18 are inserted, and is a member having a function of matching the optical axis of the optical fiber of the fiber stub 14 with the optical axis of the optical fiber of the plug ferrule 18. is there. A fiber stub 14 is inserted into the through hole of the sleeve 12 from one open end, and a plug ferrule 18 is inserted from the other open end.

  In the present invention, a so-called split sleeve having a slit (not shown) extending in the longitudinal direction can be used as the sleeve 12. When such a split sleeve is employed, the hole diameter of the through hole is slightly smaller than the outer diameter of the plug ferrule 18 in order to increase the gripping force with respect to the plug ferrule 18 inserted into the sleeve 12 (for example, a fiber stub to the through hole). It is preferable that the pressure applied to the fiber stub 14 at the time of inserting 14 is set to 0.98 N or more.

  Further, as the sleeve 12, a so-called precision sleeve (no slit) can be employed instead of the split sleeve. Examples of the material constituting the sleeve 12 include the same material as the plug ferrule 18 described above.

  The sleeve case 13 is a substantially cylindrical tubular member having an accommodation hole for accommodating the sleeve 12, and has an opening into which the plug ferrule 18 is inserted and a joint for joining to the holder 11. The diameter of the space (housing hole) for accommodating the sleeve 12 in the sleeve case 13 is configured to be slightly larger (for example, 60 μm) than the outer diameter of the sleeve 12. The opening is a portion for guiding the plug ferrule 18 when the plug ferrule 18 is inserted, and is configured to be tapered. The opening end diameter in the opening is slightly larger (for example, 0.2 mm) than the outer diameter of the plug ferrule 18. As described above, the joint is a part for joining to the holder 11.

  The material constituting the sleeve case 13 includes synthetic resin (thermoplastic resin, thermosetting resin, etc.), metal (stainless steel, copper, iron, nickel, etc.), ceramics (aluminum oxide (alumina), zirconium oxide (zirconia), etc.) ), Glass (such as quartz), and the like. Among these, it is preferable to use stainless steel like the holder 11 in order to increase the reliability by combining the thermal expansion coefficient in consideration of fixing with the holder 11.

  In this way, the fiber stub 14 is held by the holding portion (fitting hole) of the holder 11 and the sleeve case 13 is held by the sleeve holding portion, and when the light receiving module is formed, the holder 11 includes the optical element. Module is connected.

  Examples of the material constituting the holder 11 include stainless steel, copper, iron, and nickel, and stainless steel materials such as SUS304 and SF20T that are excellent in YAG weldability are preferable.

(Embodiment 5)
Next, the light receiving module 20 according to Embodiment 5 of the present invention will be described with reference to the drawings. FIG. 7 is a schematic diagram illustrating a light receiving module 20 according to an embodiment of the present invention.

  The light receiving module 20 includes the optical receptacle 10 according to the fourth embodiment, and a metal casing 17 provided with the optical element 15 and the lens 16 on the rear end surface side, and on the rear end surface side of the optical receptacle 10, It is configured by joining the casing 17 by welding. In the light receiving module 20 configured as described above, the plug ferrule 18 is inserted into the inner hole of the sleeve 12 from the front end face side of the optical receptacle 10 (opposite the end face where the optical filter 6 is disposed), and the optical fiber 19 The end face of the is brought into contact.

The plug ferrule 18 is a member for protecting the optical fiber 19 and for coordinating the central axis of the fiber stub 14 with the central axis of the plug ferrule 18 in cooperation with the sleeve 12 described later. Examples of the material constituting the plug ferrule 18 include zirconium oxide (zirconia), aluminum oxide (alumina), mullite, silicon nitride, silicon carbide, aluminum nitride and the like, ceramics containing these as main components, and glass such as crystallized glass. Metals such as ceramics, phosphor bronze, beryllium copper, brass and stainless steel, plastics such as epoxy and liquid crystal polymer, etc. are mentioned. Among them, zirconia-based ceramics (ceramics based on zirconia) having excellent weather resistance and toughness are suitable. is there. Among zirconia-based ceramics, in particular, at least one selected from the group consisting of zirconium oxide (ZrO ₂ ) as a main component and Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like is used as a stabilizer. Partially stable zirconia ceramics (mainly tetragonal crystals) are included as a more preferable material from the viewpoints of wear resistance and elastic deformation.

  The optical fiber 19 is for propagating light, and examples of the optical fiber 19 include a quartz-based optical fiber, a plastic-based optical fiber, and a multicomponent glass-based optical fiber.

  Next, functions of the light receiving module 20 will be described. First, the wavelength multiplexed signal light λ1, λ2, and λ3 transmitted from the outside by the transmission fiber is incident on the optical fiber of the plug ferrule 18 and then incident on the optical fiber 4 of the optical device 1 included in the receptacle 10. The light incident on the optical fiber 4 is transmitted by the light λ1 having a specific wavelength by the bandpass filter function of the optical filter 6, and the light having other wavelengths is reflected and removed. The transmitted light beam λ1 is condensed on the optical element 15 through the lens 16 and converted into the original electrical signal. As described above, the light receiving module 20 has an advantage that light reception detection can be performed by extracting only specific information by using the optical device with a filter of the present invention (stub in the present embodiment).

It is sectional drawing which shows the optical device with an optical filter which concerns on Embodiment 1 of this invention. FIGS. 2A and 2B are diagrams for explaining the operational effects of the present invention due to the arrangement of the filter film. FIG. 3 is an explanatory diagram for explaining the function and effect of the present invention. FIG. 4 is a cross-sectional view showing an optical device with a filter according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view showing an optical device with an optical filter according to Embodiment 3 of the present invention. It is sectional drawing which shows the optical receptacle of this invention. It is sectional drawing which shows the light reception module of this invention. It is sectional drawing which shows the conventional optical device with an optical filter.

Explanation of symbols

1, 1 ', 1'', 100 Optical device with optical filter 2 Clad 3 Core 4, 19 Optical fiber 5 Ferrule 6 Optical filter 6a Translucent support 6b Filter film 7 Optical adhesive 9''' Coreless fiber 9 " Graded index fiber (GI fiber)
9 'single mode fiber (SM fiber)
DESCRIPTION OF SYMBOLS 10 Optical receptacle 12 Sleeve 14 Fiber stub 15 Optical element 16 Lens 17 Case 18 Plug ferrule 20 Light receiving module

Claims (6)

A ferrule having an inclined portion with one end face inclined with respect to a direction orthogonal to the axial direction of the inner hole;
An optical fiber inserted into the inner hole of the ferrule;
An optical filter having a filter film that selectively transmits light in a specific wavelength band, wherein the filter film is bonded to a surface facing the inclined portion of the ferrule so as to close an inner hole opened in one end surface of the ferrule And comprising
An optical device with an optical filter, wherein the optical fiber is formed by joining a single mode fiber and a graded index fiber, and the graded index fiber is arranged on the optical filter side.   The optical device with an optical filter according to claim 1, wherein an end surface of the ferrule further has a surface that intersects the inclined portion at a predetermined angle. The optical filter is bonded to the inclined portion of the ferrule via an optical adhesive,
The thermal expansion coefficient of the optical adhesive is approximately the same as that of the translucent support and the ferrule constituting the main part of the optical filter, or between the thermal expansion coefficients thereof. The optical device with an optical filter as described.   4. The optical device with an optical filter according to claim 1, wherein the optical fiber further includes a coreless fiber bonded to the graded index fiber on the optical filter side. An optical device with a filter according to any one of claims 1 to 4,
A bottomed cylindrical holder having a fitting hole for holding one end of the ferrule;
A sleeve inserted into the other end of the ferrule;
A cylindrical sleeve case having an accommodation hole for accommodating the sleeve, one end of which is fixed to the holder;
An optical receptacle comprising: An optical receptacle according to claim 5;
A light receiving element that receives light through the optical fiber and the optical filter;
A cylindrical body joined to the holder of the optical receptacle and containing the light receiving element;
A light receiving module comprising:

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