JP5398355B2 - Fiber stub with optical isolator, optical receptacle with optical isolator, and optical module - Google Patents

Description

  The present invention relates to a semiconductor laser module that is small and densely mounted on an optical transceiver used for optical communication, and relates to a fiber stub with an optical isolator used for an optical receptacle portion of the semiconductor laser module.

  Conventional fiber stubs with optical isolators and optical receptacles and optical modules using the same are disclosed in, for example, Patent Documents 1 and 2, and the internal structure thereof will be described with reference to FIGS. FIG. 5 is a longitudinal sectional view of a main part of a conventional fiber stub with an optical isolator, and FIG. 6 is a central longitudinal sectional view of an optical module.

  The ferrule 102 is made of ceramic or glass material. The ferrule 102 has a through hole 127 having a diameter equal to or larger than the outer diameter of the optical fiber at the center, and a counterbore 121 on the rear end face 129 side. The through-hole 127 is melted and filled with glass 101 having the same refractive index as the optical fiber core as the light guide 101. The fiber stub 103 includes the ferrule 102 and a light guide (glass) 101. The rear end surface 129 of the fiber stub 103 is obliquely polished at a predetermined angle of, for example, 4 ° to 8 ° in order to suppress return light to an optical element such as a semiconductor laser due to near-end reflection. An optical isolator element 109 is installed on the rear end surface 129.

  The optical isolator element 109 includes a polarizer 106, a Faraday rotator 107, and an analyzer 108. The optical isolator element 109 is pre-rotated around the optical axis so that the angle of the transmission polarization plane of the polarizer 106 and the analyzer 108 is 45 °. Then, they are bonded together with an adhesive. Further, it is cut into a predetermined size so as to be accommodated in the counterbore part 121 of the fiber stub 103, and is formed on the rear end surface 129 so that the optical axis of the light guide 101 and the optical axis of the optical isolator element 109 substantially coincide with each other. Bonded and fixed. At this time, the transmission polarization plane of the polarizer 106 is bonded and fixed so as to be perpendicular or horizontal to the oblique polishing direction of the rear end face 129.

  A cylindrical magnet 110 that applies a magnetic field to the Faraday rotator 107 is disposed on the outer periphery of the fiber stub 103. The optical isolator element 109 functions as the optical isolator 111 by the magnetic field of the magnet 110 by being fixed to the position surrounding the optical isolator element 109 accommodated in the counterbore part 121 of the fiber stub 103 inside the magnet 110 by an adhesive or the like. .

  FIG. 6 is a longitudinal sectional view when the fiber stub 125 with an optical isolator of FIG. 5 is used in an optical module. The optical module is a coaxial semiconductor laser module having an optical axis as a central axis, and has a cylindrical casing as a whole. Further, an optical receptacle type to which the plug ferrule 131 is connected is shown. Illustration of the lead wire for wiring to the LD (laser diode), the PD for monitoring (photodiode) and the like is omitted.

  The conventional optical module includes an optical unit 100 including a semiconductor laser 112, a heat sink 113, a metal stem 114, a lens 115, and a lens holder 116, an optical isolator 111, and an optical receptacle 117.

  The semiconductor laser 112 in the optical unit 100 portion is mounted on the heat sink 113 by solder. The heat sink 113 is mounted on the support portion 114a of the metal stem 114 and is similarly fixed by solder. The lens 115 is fixed to a lens holder 116 made of metal by low melting point glass or the like, and the lens holder 116 is resistance-welded to the metal stem 114.

  The fiber stub 103 of the optical receptacle 117 is press-fitted into the second through hole 128 of the metal holder 105, and a second counterbore part 133 for fixing the magnet 110 is provided on the rear end side of the metal holder 105. . Further, a sleeve 118 made of ceramics or metal is inserted at the tip end side of the fiber stub 103, and a shell 119 made of metal or plastic is inserted and fixed to the metal holder 105 so as to cover the sleeve 18, and an optical receptacle 117 is formed. Has been.

  In such an optical module, the light emitted from the semiconductor laser 112 is condensed by the lens 115, and light is transmitted through the optical isolator 111 that prevents the reflected return light to the semiconductor laser 112 and the light guide body 101 of the fiber stub 103. The connector is assembled so as to be optically coupled to the tip of the optical fiber 132 installed at the center of the plug ferrule 131 of the connector.

  In assembling the optical module, the position of the optical receptacle 117 is adjusted by the lens 115 so that the tip position of the optical fiber 132 is in focus, and then the metal holder 105 of the optical receptacle 117 is fixed to the lens holder 116 by laser welding or the like. Is done. A third counterbore 134 is formed on the inner periphery 120 of the lens holder 116 so that the magnet 110 of the optical isolator 111 does not come into contact with the optical receptacle 117 when the position of the optical receptacle 117 is adjusted.

JP 2006-145987 A JP 2006-113360 A

  However, the conventional structure shown in FIGS. 5 and 6 has a problem that the optical isolator element 109 cannot be easily positioned when the optical isolator element 109 is bonded and fixed to the rear end surface 129 of the fiber stub 103. In other words, the optical surface of the optical isolator element 109 must be arranged in alignment with the center of the through hole 127, but the central axis of the through hole 127 and the center of the optical surface of the optical isolator element 109 are aligned and bonded. There is a problem that it is difficult.

  For this reason, the area of the optical surface of the optical isolator element 109 installed and fixed on the rear end surface 129 of the fiber stub 103 needs to be increased in consideration of positional deviation. For example, with respect to a beam diameter of about 0.3 mm incident on the optical isolator element 109, there is a problem that the size of the optical surface of the optical isolator 109 cannot be smaller than 0.45 mm length × 0.45 mm width.

  An object of the present invention has been devised in view of the above-described problems, and is to provide a fiber stub with an optical isolator, an optical receptacle with an optical isolator, and an optical module that can be easily assembled using a small optical isolator element. is there.

In view of the above problems, a fiber stub with an optical isolator according to an embodiment of the present invention has a cylindrical shape, and a polarizer and a Faraday rotator on a rear end surface of a ferrule in which a light guide is disposed in a central through hole. A fiber stub with an optical isolator in which an optical isolator element comprising: an optical isolator element having a width slightly larger than the width of the optical isolator element and inclined with respect to the rear end surface is formed so that the grooves having bottom surfaces traverses an opening of the through hole, in the groove, the optical isolator element is characterized in that it is installed to cover the opening.

  The optical isolator element has two parallel sides in a cross-sectional shape perpendicular to the optical axis. The distance between the two sides is less than the width of the groove, and the two sides and the groove are parallel to each other. Thus, it is preferable to be fitted in the groove.

  Moreover, it is preferable that the cylindrical magnet which applies a magnetic field to the said optical isolator element is installed in the said rear end surface of the said ferrule.

  The light guide is preferably made of an elastically deformable optical transparent body having a refractive index substantially equal to the core of the optical fiber connected to the light guide.

  It is preferable that the inner diameter of the through hole is greater than or equal to the outer diameter of the optical fiber.

  An optical receptacle according to an embodiment of the present invention includes a fiber stub with an optical isolator as described above, a sleeve in which a front end portion of the ferrule is inserted into one side opening of a through hole, and a rear end side outer peripheral surface of the ferrule. And a holder for gripping.

  Furthermore, in the optical receptacle with an optical isolator, it is preferable that a holding portion of the holder that holds the outer peripheral surface of the rear end side of the ferrule extends so as to accommodate a part of the magnet.

  In addition, an inner diameter of the extending portion of the holder extended to accommodate a part of the magnet is smaller than an inner diameter of the holding portion of the holder that holds the ferrule, and the holding portion and the extending portion It is preferable that a rear end surface of the ferrule is brought into contact with a step surface formed therebetween and fixed by an adhesive.

  An optical module according to an embodiment of the present invention includes the optical receptacle with the optical isolator, and an optical unit having an optical element arranged to be optically coupled to the optical isolator. .

  According to a fiber stub with an optical isolator according to an embodiment of the present invention, a groove having a width larger than the diameter of the through hole and having a bottom surface inclined with respect to the rear end surface is formed on the rear end surface of the ferrule. Since the optical isolator element is installed so as to cross the opening so as to cover the opening, the optical isolator element can be installed inclined along the bottom surface of the groove. Since the optical isolator element is installed in the groove, an optical isolator element small enough to cover the opening is sufficient, and the assembly of the optical isolator element is facilitated. The rear end surface of the ferrule only forms a groove, and the ferrule can be easily processed.

  The optical isolator element has two sides parallel to each other in a cross-sectional shape perpendicular to the optical axis. The distance between the two sides is less than the width of the groove, and the groove is formed so that the two sides are parallel to the groove. When fitted, the positioning of the optical isolator element is further facilitated, and displacement in the rotational direction with respect to the left and right and the optical axis during adhesive fixing can be suppressed. For this reason, the junction area of the optical isolator element can be reduced as much as possible, and this makes it possible to reduce the size of the optical isolator element as compared with the conventional structure.

  When a cylindrical magnet for applying a magnetic field to the optical isolator element is installed on the rear end face of the ferrule, the outer peripheral portion of the rear end face does not need to be an inclined surface, so that it becomes easy to install the cylindrical magnet.

  Further, when the light guide is formed of an elastically deformable optical transparent body having a refractive index substantially equal to that of the optical fiber core connected to the light guide, the light guide is connected to the connection portion between the light guide and the optical fiber. The optical loss that occurs is small, optical polishing of both ends of the fiber stub is unnecessary, and even if the tip of the optical connector plug ferrule is repeatedly abutted against the tip of the fiber stub, the light guide is damaged. Not stick.

  When the inner diameter of the through hole is equal to or larger than the outer shape of the optical fiber, it is difficult to cause an optical loss between the optical fiber and the optical transparent body.

  Further, according to the optical receptacle with an optical isolator according to an embodiment of the present invention, the optical isolator element can be miniaturized, and the optical stub with the optical isolator can be miniaturized. It can be an optical receptacle.

  Furthermore, when the holder holding part that holds the outer peripheral surface of the rear end side of the ferrule is extended so as to accommodate a part of the magnet, the optical isolator is accommodated inside the lens holder inner diameter of an optical module such as a semiconductor laser. There is no need to provide a counterbore part. Further, by inserting and fixing a part of the magnet in the through hole of the holder, further downsizing and cost reduction can be achieved.

  In addition, when the rear end surface of the ferrule is in contact with the step surface formed between the holding portion and the extending portion of the holder and is fixed by an adhesive, the plug can be plugged even if the fiber stub length is shortened. By pressing the ferrule against the tip of the fiber stub, the fiber stub can be made difficult to fall off. Further, by adhering and fixing the fiber stub, the tolerance of the inner diameter of the holder can be relaxed as compared with the case where the fiber stub is press-fitted and fixed.

  According to an optical module according to an embodiment of the present invention, the optical module includes the optical receptacle with the optical isolator and an optical unit having an optical element arranged so as to be optically coupled to the optical isolator. Can provide modules.

It is a longitudinal cross-sectional view which shows an example of embodiment of the fiber stub with an optical isolator of this invention. It is a longitudinal cross-sectional view which shows an example of embodiment of the semiconductor laser module of this invention. 1 is a perspective view showing an optical isolator element and a fiber stub in an embodiment of a fiber stub with an optical isolator of the present invention. It is a longitudinal cross-sectional view which shows the other example of embodiment of the semiconductor laser module of this invention. It is a longitudinal cross-sectional view which shows the example of the conventional fiber stub with an optical isolator. It is a center part longitudinal cross-sectional view which shows the example of the conventional semiconductor laser module.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a fiber stub 25 with an optical isolator according to the present invention. The fiber stub 3 used in the present invention includes a ferrule 2 and a light guide 1. The ferrule 2 is made of a ceramic material or a glass material, and has a through hole 27 in the central portion axial direction. The through-hole 27 is provided in a round hole shape matching the diameter of the light beam passing through the inside. The through hole 27 is filled with an optically transparent light guide 1 (hereinafter also referred to as an optical transparent body 1).

  The rear end surface 29 of the fiber stub 3 has a groove 22 having a width slightly larger than the diameter of the through hole 27, for example, a width of 0.35 to 0.4 mm with respect to a diameter of 0.1255 to 0.1265 mm of the through hole 27. It is formed so as to cross the central through hole 27. The groove 22 is provided by dicing or the like so as to be inclined by 8 ° with respect to a plane perpendicular to the optical axis in order to suppress return light due to near-end reflection to the optical element such as the semiconductor laser 12. The inclination direction may be inclined in the width direction of the groove 22, but may be inclined in the direction in which the groove 22 is formed from one end to the other end of the groove 22.

  The groove 22 is provided from the end of the position where the optical isolator element 9 is installed as a starting point 23, from there to the outer peripheral surface of the ferrule 2 across the through hole 27. Since the optical isolator element 9 is installed at a shallow position of the groove 22 inside the groove 22 from the starting point 23 of the groove 22, the optical isolator element 9 can be easily chucked, and the bottom surface of the groove 22 to be bonded is visually confirmed. It is easy to do.

  The optical transparent body 1 is made of glass or resin, but it is preferable to use the elastic transparent optical body 1 made of a gel material or the like. Moreover, it is preferable that the optical transparent body 1 has a refractive index of 1.4 to 1.5 which is substantially equivalent to the refractive index 1.46 of the core portion of the optical fiber. For example, an epoxy gel resin having a glass transition temperature Tg of −40 ° C. or less may be used. In general, the end surface 24 of the fiber stub 3 used for the optical receptacle 17 is subjected to curved surface polishing so as to abut the end of the plug ferrule 31 of the optical connector. The tip 4 of the optical transparent body 1 is formed to protrude slightly from the tip surface 24 by surface tension. As a result, the step of polishing the tip surface 24 into a convex curved surface can be omitted. The optical transparent body 1 is filled in, for example, a through hole 27 having a diameter of 0.125 mm to 0.3 mm that is equal to or larger than the diameter of the optical fiber (0.125 mm).

  The starting point 23 of the groove 22 is about 0.35 mm long and 0.35 mm wide on the surface 26 perpendicular to the optical axis as shown in FIG. It is preferable to be formed to be positioned at 0.175 mm. If the beam diameter of the incident light is about 0.3 mm, the optical isolator element 9 is formed to have a length of about 0.35 mm × 0.35 mm which is slightly larger than that. When the optical isolator element 9 is mounted and fixed in the groove 22, the horizontal direction is accommodated in the width direction of the groove 22 formed with a width equal to or greater than the horizontal direction of the optical isolator element 9, and the vertical direction targets the starting point 23 of the inclined surface. It is positioned and installed. If the width of the groove 22 is formed to be slightly longer than the lateral dimension of the optical isolator element 9, when the optical isolator element 9 is bonded to the fiber stub 3 and fixed, the groove 22 causes a positional shift in the left and right and rotation directions. Therefore, the optical isolator element 9 can be reduced in size and can be mounted substantially at the center of the opening of the through hole 27.

  The inclined surface of the groove 22 may be formed after the groove 22 is slightly dug down in the optical axis direction. Also in this case, the groove 22 is formed so that the starting point 23 of the groove 22 is at the same position as in the above case.

  The optical isolator element 9 includes a polarizer 6, a Faraday rotator 7, and an analyzer 8. Then, after rotating and aligning in advance so that the angle of the polarization plane of polarization of the polarizer 6 and the analyzer 8 is 45 °, each is pasted with an adhesive, and then cut into a predetermined size to obtain individual optical isolator elements. 9 is formed. Since the incident / exit surface of the optical isolator element 9 is installed in parallel with the surface of the groove 22 of the fiber stub 3 having, for example, an inclination angle of 8 °, it becomes a surface having an inclination angle of 8 ° relative to the optical axis. If the side surface of the optical isolator element 9 is formed so as to be parallel to the optical axis when the optical isolator element 9 is installed on an inclined surface, the optical isolator element 9 can be accommodated in a compact manner. Further, the direction of the transmission polarization plane can be distinguished from the angle formed by the incident surface and the side surface.

  The cylindrical magnet 10 for applying a magnetic field to the Faraday rotator 7 is preferably set to have an outer diameter equal to or smaller than a diameter of 1.25 mm, which is the minimum outer diameter of the fiber stub 3 generally used. . Such a magnet 10 is fixed to the rear end surface 29 of the fiber stub 3 with an adhesive so as to surround the optical isolator element 9 disposed inside the cylinder. The optical isolator element 9 and the magnet 10 constitute an optical isolator 11.

  If the cylindrical magnet 10 is bonded to the rear end surface 29 perpendicular to the optical axis, the cylindrical magnet 10 can be housed more compactly than when it is bonded to the inclined surface. Further, the bonding work is facilitated, and it is easy to ensure the bonding strength.

  If the outer diameter of the magnet 10 is equal to or smaller than the outer diameter of the fiber stub 3, the magnet 10 is prevented from protruding outward from the outer peripheral surface of the fiber stub 3, and the entire magnet 10 and the fiber stub 3 are accommodated in a cylindrical space. it can. As a result, when designing an optical module to be described later, as shown in FIG. 2, a part of the magnet 10 can be accommodated together with the fiber stub 3 in the second through hole 28 of the metal holder 5. The shape of 5 can be simplified.

  Thus, the fiber stub 25 and the optical isolator 11 constitute a fiber stub 25 with an optical isolator. By using a fiber stub with an optical isolator according to an embodiment of the present invention, the optical receptacle 17 and the optical module can be reduced in size.

  FIG. 2 is a longitudinal sectional view showing an optical receptacle 30 with an optical isolator and an optical module according to an embodiment of the present invention, and shows a coaxial type semiconductor laser module. In addition, illustration of the lead wire for wiring to LD (laser diode), PD for monitoring (photodiode), etc. is abbreviate | omitted.

  An optical receptacle 30 with an optical isolator according to an embodiment of the present invention includes the above-described fiber stub 25 with an optical isolator and the optical receptacle 17. The optical receptacle 17 includes a metal holder 5 that holds the rear end portion of the ferrule, and a sleeve 18 into which the front end portion of the ferrule is inserted. A shell 19 that covers the outside of the sleeve 18 to protect the sleeve 18 and whose rear end is held by the holder 5 may be provided.

  The metal holder 5 is generally formed in a cup shape with a bottom, and a second through hole 28 penetrating in the thickness direction from the center of the bottom is formed, and a fiber stub 25 with an optical isolator is formed in the second through hole 28. The rear end surface 29 side is configured to be press-fitted and retained. That is, the rear end surface 19 side of the fiber stub 25 is press-fitted into the through hole 28 so that the rear end surface 19 side of the fiber stub 25 is held in the through hole 28 of the holder. Further, the through hole 28 may be extended, and a part of the optical isolator 11 may be accommodated in the extended portion 28 b of the through hole 28.

  As the material of the metal holder 5, a stainless material having excellent corrosion resistance and weldability, such as SUS304, is used, but a weldable material such as iron or nickel may be used.

  The sleeve 18 is a split sleeve obtained by slitting a cylinder made of phosphor bronze, a ceramic material, or the like in the entire vertical direction, and the plug ferrule 31 for an optical connector can be held from one side opening.

  The shell 19 is formed in a cylindrical shape, and the sleeve 18 is separated from the side wall of the metal holder 5 and is accommodated in its entirety so as to be press-fitted and held in the metal holder 5. Metal or plastic is used as the material of the shell 19.

  The fiber stub 3 is inserted into the other opening of the sleeve 18, and the shell 19 is inserted and fixed in the metal holder 5 so as to cover the sleeve 18, thereby forming the optical receptacle 17.

  An optical module according to an embodiment of the present invention includes an optical receptacle 30 with an optical isolator according to an embodiment of the present invention, and an optical unit 100. The optical unit 100 accommodates an optical element 12 therein, and the optical element 12 is optically coupled to an optical fiber 32 of a plug ferrule 31 for an optical connector via an optical receptacle 30 with an optical isolator and an optical isolator element 9. Yes.

  The optical unit 100 includes a semiconductor laser 12, a heat sink 13, a metal stem 14, a lens 15, and a lens holder 16. The optical receptacle 30 with an optical isolator is configured by attaching the optical isolator 11 to the rear end face 29 side of the optical receptacle 17 described above.

  The semiconductor laser 12 is mounted on the heat sink 13 by solder, and the heat sink 13 is similarly mounted and fixed by solder on a metal stem 14 in which a support portion 14a is vertically projected on a cylindrical plane. The lens holder 16 is formed in a cylindrical shape with a material that can be resistance welded around the cylindrical surface of the metal stem 14. The lens holder 16 is formed so as to accommodate the semiconductor laser 12 and the heat sink 13, and the lens 15 is fixed in the middle of the laser optical path of the semiconductor laser 12 on the inner periphery 20 with low melting point glass or the like.

  The magnet 10 of the optical isolator 11 may be held in a state in which a part thereof is inserted and fixed in the second through hole 28 of the metal holder 5 in order to achieve downsizing and increase the adhesive strength. Therefore, the diameter of the outer peripheral surface of the magnet 10 is substantially the same as the diameter of the outer peripheral surface of the ferrule 3. The magnet 10 is bonded to the rear end surface 29 perpendicular to the optical axis. By forming one second through hole 28 having the same inner diameter as the second through hole 28, the optical isolator 11 can be accommodated together with the fiber stub 3. With such a configuration, the magnet 10 does not come into contact with the inner peripheral surface 20 of the lens holder 16 when the optical receptacle 17 is aligned with the inner peripheral surface 20 of the lens holder 16. An optical module that can be priced and can be bonded at both the groove 22 of the fiber stub 3 and the second through hole 28 of the metal holder 5 to increase the bonding area, increase the bonding strength, and improve the reliability. Can be provided.

  Further, the light emitted from the semiconductor laser 12 is collected by the lens 15, and the optical ferrule 31 at the center of the optical connector is connected via the optical isolator 11 and the optical transparent body 1 to prevent the reflected return light to the semiconductor laser 12. It is introduced into the tip surface of the optical fiber 32. The optical receptacle 30 with optical isolator and the optical unit 100 adjust the position of the optical receptacle 17 so that the optical fiber 32 is positioned at the position of the condensed light beam, and then laser the metal holder 5 of the optical receptacle 17 to the lens holder 16. It is assembled by being fixed by welding or the like.

  At this time, since the outer diameter of the optical isolator 11 is sufficiently small with respect to the inner circumference 20 of the lens holder 16, there is no need to provide the third counterbore portion 134 dedicated to the optical isolator 111 as shown in the conventional example of FIG. The module can be miniaturized. Further, since the optical transparent body 1 is formed of a gel-like resin, optical polishing of both end surfaces is not necessary, and the tip of the plug ferrule 31 of the optical connector is repeatedly fitted to the tip surface 24 of the fiber stub 3. The optically transparent body 1 is hardly scratched even if it is abutted by.

  FIG. 4 is a longitudinal sectional view showing an example of an embodiment formed by changing the inner diameter of the through hole 28 of the holder 5 of FIG. 2 in the middle, and shows a coaxial type semiconductor laser module. That is, the holder 5 has an inner diameter of the extending portion (through hole) 28b in which the magnet 10 is accommodated smaller than the inner diameter of the through hole 28a serving as a grip portion for gripping the ferrule 31, and the holder 5 has a through hole 28a and a through hole 28b. It is formed so as to have a stepped surface 28c therebetween. The rear end surface 29 of the fiber stub 3 is brought into contact with the stepped surface 28c, and the rear end portion of the fiber stub 3 rear end surface 29 is bonded to the inner wall surface of the through hole 28a.

  When the optical transparent body 1 is an optical fiber, the focal position of the light collected by the lens 15 is brought to the core portion of the optical fiber on the rear end face 29. The optical transparent body 1 is gelled. In the case of forming with a resin, the focal position of the light is set to be the core portion of the optical fiber 32 on the distal end surface 24 side.

  By the way, when the length of the fiber stub 3 is shortened to make the receptacle 17 small, for example, 2 mm or less, the gripping force of the fiber stub 3 by the through hole 28a may not be sufficient. In this case, the plug ferrule 31 is formed by providing the through hole 28b in the holder 5 and bringing the rear end surface 29 of the fiber stub 3 into contact with the stepped surface 28c formed between the through hole 28a and the through hole 28b having different inner diameters. Even if the tip of the fiber stub 3 is pressed, the fiber stub 3 can be hardly removed from the through hole 28. Moreover, if the fixing method using an adhesive is employed instead of the conventional press-fitting and fixing method, the inner diameter accuracy of the through hole 28a of the holder 5 can be relaxed. For example, when press-fitting and fixing, the processing accuracy can be relaxed from a processing accuracy of 10 μm or less to a processing accuracy of ± 20 μm or less.

  Hereinafter, as an example of the present invention, an optical module including the optical isolator-equipped fiber stub 11 and the optical isolator-equipped optical receptacle 30 shown in FIGS. 1 and 2 was produced. The optical module was a coaxial optical receptacle type semiconductor laser module.

  In FIG. 1, a groove 22 having a width of 0.4 mm is formed on the rear end surface 29 of the fiber stub 3 so as to cross the central through-hole 27 and the bottom surface is inclined by 8 ° with respect to the plane perpendicular to the optical axis. Provided by processing.

  The fiber stub 3 has a total length of 1 mm, an outer diameter of 1.25 mm, and a through hole 27 having a diameter of 0.2 mm provided in the central portion in the axial direction. The through-hole 27 was filled with an epoxy gel thermosetting resin having a refractive index of 1.48 and a glass transition temperature Tg of −50 ° C. as the optical transparent body 1. The thermosetting resin was filled to the extent that it protruded slightly from the opening of the through hole 27 by the surface tension from the tip surface 24 of the fiber stub 3.

  The starting point 23 of the inclined surface of the groove 22 was set at a position 0.175 mm from the center of the through hole 27 as shown in FIG.

  On the other hand, the optical isolator element 9 was formed by cutting a vertical cross section 26 with respect to the optical axis into a length of 0.35 mm × width of 0.35 mm. Then, as shown in FIG. 3, the bottom surface of the groove 22 having a bottom surface formed at an inclination angle of 8 ° was fixed with an adhesive so that the starting point 23 and the side surface of the optical isolator element 9 coincided with each other. The transmission polarization plane of the polarizer 6 was set to be perpendicular to the extending direction of the groove 22.

  A cylindrical magnet 10 for applying a magnetic field to the Faraday rotator 7 was used with an outer diameter of 1.2 mm, an inner diameter of 0.6 mm, and a length of 1 mm. And it fixed to the outer peripheral part of the rear-end surface 29 orthogonal to the optical axis of the fiber stub 3 with the adhesive agent. Thus, a fiber stub 25 with an optical isolator was formed.

  Next, as shown in FIG. 2, the semiconductor laser 12 was mounted and fixed on the heat sink 13 by soldering, and the heat sink 13 was similarly mounted and fixed on the metal stem 14 by soldering. The lens 15 was fixed to a lens holder 16 made of stainless steel with low melting point glass, and the lens holder 16 was resistance welded to the metal stem 14.

  In the fiber stub 25 with an optical isolator, the rear end surface 29 of the fiber stub 3 is press-fitted and fixed at a position where it does not protrude from the second through hole 28 of the metal holder 5, and a sleeve 18 made of zirconia material is inserted on the tip side. Then, a shell 19 made of a stainless material was covered so as to cover the sleeve 18 and press-fitted and fixed to the metal holder 5 to form the optical receptacle 17.

  The gap between the outer peripheral surface of the magnet 10 and the second through hole 28 of the metal holder 5 was filled with an adhesive to reinforce the adhesive strength. Then, the position of the optical receptacle 17 is adjusted so that the light condensed by the lens 15 is focused on the distal end surface of the optical fiber 32 inserted into the plug ferrule 31 on the optical connector side fitted in the optical receptacle 17. Thereafter, the metal holder 5 of the optical receptacle 17 was fixed to the lens holder 16 by laser welding.

  Table 1 shows the polishing time of both end surfaces of the fiber stub 3 of the conventional semiconductor laser module and the semiconductor laser module according to the present embodiment, the vertical sectional area with respect to the optical axis of the optical isolator element 9, the outer diameter of the magnet 10, the metal holder 5 and the lens. The result of putting together the presence or absence of the counterbore part for exclusive use of the optical isolator 11 of the internal diameter of the holder 16, the adhesion part confirmation between the optical isolator element 9 and the fiber stub 3, and the presence or absence of the damage | wound produced in the light guide body of the fiber stub is shown.

本実施例の光モジュールでは、ファイバスタブ３の中央の貫通孔２７内の光学的透明体１として弾性変形可能なゲル状の樹脂を採用したことで、両端面の研磨を不要とし、約５分要していた研磨時の作業時間を１００％低減できた。また、溝２２に接着固定する光アイソレータ素子９の光軸に対する垂直断面２６の面積は、従来例の約０．２ｍｍ^２に比し、本実施例では約０．１２ｍｍ^２と、約４０％低減できたことで光アイソレータ素子９の取り数を増やし、低価格化できた。

In the optical module of the present embodiment, since the elastic resin 1 in the center through-hole 27 of the fiber stub 3 is made of an elastically deformable gel-like resin, it is not necessary to polish both end surfaces, and about 5 minutes. The work time required for polishing could be reduced by 100%. Further, the area of the vertical cross section 26 with respect to the optical axis of the optical isolator element 9 bonded and fixed to the groove 22 is about 0.12 mm ^{2 in} this embodiment, which is about 40% less than that of the conventional example of about 0.2 mm ^2. As a result, the number of optical isolator elements 9 can be increased and the price can be reduced.

  Furthermore, the outer diameter of the cylindrical magnet 10 is set to φ1.2 mm, which is 40% lower than that of the conventional example, and the cylindrical magnet 10 is inserted into the second through hole 28 of the metal holder 5 to be inserted into the rear end surface 29 of the fiber stub 3 and the second through hole. By fixing in the hole 28, the optical isolator 11 was reduced in size without impairing the adhesive strength, and the second counterbore portion 33 of the metal holder 5 was not required.

  Further, by making the outer diameter of the optical isolator 11 smaller than the outer diameter of the fiber stub 3, it is necessary to provide a dedicated third counterbore portion 34 for housing the optical isolator 11 on the inner periphery 20 of the lens holder 16 of the optical module. In addition, the price of the lens holder 16 could be reduced.

  Further, the adhesive portion between the optical isolator element 9 and the fiber stub 3 before the magnet 10 is attached is compared with the structure having the counterbore portion 21 of the conventional example, and the groove 22 is visible, so that the adhesive meniscus is filled. Can be confirmed and managed, and the reliability has been improved.

  Further, when the tip of the plug ferrule 31 of the optical connector fitted to the optical receptacle 17 is repeatedly abutted against the tip of the fiber stub 3, the optical transparent body 1 made of an elastically deformable gel resin is scratched. I was able to confirm that there was no.

1. Light guide (optically transparent body)
DESCRIPTION OF SYMBOLS 2 ... Ferrule 3 ... Fiber stub 5 ... Holder 6 ... Polarizer 7 ... Faraday rotator 8 ... Analyzer 9 ... Optical isolator element 10 ... Magnet 11 ... Optical isolator 12 ... Semiconductor laser 13 ... Heat sink 14 ... Metal stem 14a ... Support part DESCRIPTION OF SYMBOLS 15 ... Lens 16 ... Lens holder 17 ... Receptacle 18 ... Sleeve 19 ... Shell 20 ... Inner circumference 22 ... Groove part 23 ... Starting point 24 ... Front end surface 25 ... Fiber stub with an optical isolator 26 ... Vertical section 27 ... Through-hole 28 ... Through-hole 29 ... rear end face 30 ... optical receptacle with optical isolator 31 ... plug ferrule 32 ... optical fiber 100 ... optical unit

Claims (9)

A fiber stub with an optical isolator in which an optical isolator element comprising a polarizer and a Faraday rotator is installed on the rear end face of a ferrule having a cylindrical shape and a light guide disposed in a central through hole. A groove having a width slightly larger than the width of the optical isolator element and having a bottom surface inclined with respect to the rear end face is formed so as to cross the opening of the through hole, starting from the end of the installation position of the isolator element. in the groove, with an optical isolator fiber stub, characterized in that said optical isolator element is disposed so as to cover the opening. The optical isolator element has two parallel sides in a cross-sectional shape perpendicular to the optical axis, the distance between the two sides is less than the width of the groove, and the two sides and the groove are parallel to each other. The fiber stub with an optical isolator according to claim 1, wherein the fiber stub is fitted in the groove. 3. The fiber stub with an optical isolator according to claim 1, wherein a cylindrical magnet that applies a magnetic field to the optical isolator element is disposed on the rear end face of the ferrule. 4. The light guide body is made of an elastically deformable optical transparent body having a refractive index substantially equal to that of an optical fiber core connected to the light guide body. Fiber stub with optical isolator as described. The fiber stub with an optical isolator according to any one of claims 1 to 4, wherein an inner diameter of the through hole is equal to or larger than an outer diameter of the optical fiber. A fiber stub with an optical isolator according to any one of claims 1 to 5, a sleeve in which a tip end portion of the ferrule is inserted into one side opening of a through hole, and a holder for gripping a rear end side outer peripheral surface of the ferrule. An optical receptacle with an optical isolator. 7. The optical receptacle with an optical isolator according to claim 6, wherein a grip portion of the holder that grips the outer peripheral surface of the rear end side of the ferrule extends so as to accommodate a part of the magnet. An inner diameter of the extending portion of the holder extended to accommodate a part of the magnet is smaller than an inner diameter of the gripping portion of the holder that grips the ferrule, and is between the gripping portion and the extending portion. 8. The optical receptacle with an optical isolator according to claim 7, wherein a rear end surface of the ferrule is brought into contact with the formed step surface and is fixed by an adhesive. 9. An optical module comprising: the optical receptacle with an optical isolator according to claim 6; and an optical unit having an optical element disposed so as to be optically coupled to the optical isolator.

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