JP2008268892A - Optical isolator module and optical element module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical isolator module and an optical element module which have high reliability by suppressing falling-off of an isolator. <P>SOLUTION: The optical isolator module is equipped with: an optical isolator element 10 having a pair of opposed light entering/exiting surfaces, a pair of side surfaces positioned in a direction crossing with the pair of light entering/exiting surfaces, and a base 10a positioned between the pair of light entering/exiting surfaces; and a tubular body 32 arranged so that one end face 32b opening at one end side of a through-hole 32a through which light is transferred may be opposed to one light entering/exiting surface. The tubular body 32 has a support part 32c extending from the one end face 32b, and the optical isolator element 10 is fixed in the support part 32c by the base 10a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical isolator module having an optical isolator that is built in an optical element module such as a transmitter for optical communication and suppresses reflected return light to a light emitting element such as an LD (laser diode), and an optical device on which the optical isolator module is mounted. The present invention relates to an element module.

  Optical modules for optical communication are becoming smaller with higher speed and wider bandwidth. In particular, optical isolator modules required for long-distance systems are required to be more reliable with smaller size. Such an optical isolator module is disclosed in Patent Document 1, for example.

  FIG. 5 is a longitudinal sectional view showing a conventional optical isolator module in which an optical isolator is attached to an optical fiber terminal. The optical isolator module 400 includes an optical isolator unit 200 including an optical isolator element 100 and a magnet 210, and an optical fiber terminal 300 including an optical fiber 31, a cylindrical body 32, and the like.

  The optical isolator element 100 includes two polarizers 111 and a Faraday rotator 112 interposed therebetween, and is bonded and fixed by an adhesive. The optical isolator element 100 is bonded and fixed to the distal end surface 333 of the cylindrical body 332 so that the light exit surface of the polarizer 111 on the light exit side covers the end surface of the optical fiber 331.

In order to apply a magnetic field to the Faraday rotator 112, the magnet 210 is inserted into the outer peripheral portion of the cylindrical body 332 of the optical fiber terminal 300 so as to cover the optical isolator element 100, and is fixed by an adhesive. 100 and the magnet 210 constitute an optical isolator section 200. In this way, the optical isolator unit 200 and the optical fiber terminal 300 are integrally assembled to form the optical isolator module 400.
JP 2000-162475 A

  In the conventional optical isolator module 400, the bonding surface between the optical isolator element 100 and the cylindrical body 332 of the optical fiber terminal 300 is only the distal end surface 333 of the cylindrical body 332. Therefore, in the optical isolator module 400, particularly when used for a long-distance high-reliability optical module, it is necessary to be able to withstand after a long-term reliability test such as in a high-temperature and high-humidity environment. As a result, the possibility that the optical isolator element 100 falls off from the distal end surface 333 is increased.

  Therefore, the present invention has been devised in view of the above-described problems, and an object of the present invention is to provide an optical isolator module and an optical element module that suppress the dropping of the optical isolator and have high reliability. .

  In view of the above problems, the optical isolator module of the present invention includes a pair of opposing light incident / exit surfaces, a pair of side surfaces positioned in a direction intersecting the pair of light incident / exit surfaces, and a pair of the light incident / exit surfaces. An optical isolator element having a bottom surface positioned, and a cylindrical body arranged so that one end surface opened on one end side of a through hole through which light is transmitted faces one of the light incident / exit surfaces, The cylindrical body has a support portion extending from one end surface, and the optical isolator element is fixed to the support portion at the bottom surface.

  In the optical isolator module of the present invention, the optical isolator element is characterized in that one of the light incident / exit surfaces is fixed to one end surface of the cylindrical body with a translucent adhesive.

  Furthermore, in the optical isolator module of the present invention, the support portion protrudes in the same direction as the longitudinal direction of the cylindrical body.

  Moreover, the optical isolator module of this invention WHEREIN: The one end surface of the said cylindrical body is an inclined surface inclined with respect to the direction orthogonal to the axial direction of the said through-hole.

  Furthermore, in the optical isolator module of the present invention, the support portion is formed integrally with the cylindrical body.

  The cylindrical body has a pair of wall portions extending from one end surface so as to face the side surface of the optical isolator element, and the side surface of the optical isolator element is fixed to the wall portion with the adhesive. The wall portion is formed integrally with the cylindrical body.

  In the optical isolator module of the present invention, the optical isolator element includes two polarizers each having the light incident surface, a Faraday rotator disposed between the two polarizers, and at least the Faraday rotator. And a cylindrical magnet inserted in the outer peripheral portion of one end of the cylindrical body so as to cover the optical isolator.

  In the optical isolator module and the optical element module according to the present invention, since the optical isolator element is fixed on the support portion extending from the one end surface of the cylindrical body, the optical isolator element is supported by the side surface of the support portion. be able to. As a result, in the present invention, since the optical isolator element can be prevented from dropping from the cylindrical body, the reliability can be improved.

  Hereinafter, embodiments of an optical isolator module of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an optical isolator module 40 according to an embodiment of the present invention. The optical isolator module 40 includes an optical isolator unit 20 including an optical isolator element 10 and a magnet 21, and an optical fiber terminal 30.

  The optical isolator element 10 includes two polarizers 11 and 11 ′ and a Faraday rotator 12 interposed between the polarizers 11 and 11 ′. The optical isolator element 10 is bonded with a light-transmitting adhesive (for example, an adhesive made of an epoxy resin). The optical isolator element 10 has a pair of opposing light incident / exit surfaces, a pair of side surfaces positioned in a direction intersecting with the pair of light incident / exit surfaces, and a bottom surface positioned between the pair of light incident / exit surfaces.

  The Faraday rotator 12 is a member that bears a function (Faraday effect) that rotates the polarization direction of incident light by a predetermined angle by applying a predetermined magnetic field, and is made of, for example, a bismuth-substituted garnet crystal. The thickness of the Faraday rotator 12 is set so that, for example, the polarization direction of incident light rotates by 45 °. Further, the Faraday rotator 12 only needs to have a shape having at least two light incident / exit surfaces, and examples thereof include various shapes such as a flat plate shape, a disc shape, and a wedge shape. The Faraday rotator 12 is made of, for example, a bismuth-substituted garnet or YIG garnet added with Tb, Gd, or Ho. Note that when the Faraday rotator 3 is a self-bias type that does not require application of a magnetic field, the magnet 21 may not be attached.

  The polarizers 11 and 11 ′ are members for selectively transmitting light in the polarization direction of a predetermined angle. The light transmission polarization direction of the polarizer 11 and the light transmission polarization direction of the polarizer 11 ′ are The Faraday rotator 12 is arranged so as to be shifted by an angle equivalent to the rotation angle in the polarization direction of the light. That is, if the polarization direction of the light incident on the Faraday rotator 12 is set to rotate by 45 °, the light transmission polarization direction of the polarizer 11 and the light transmission polarization direction of the polarizer 11 ′ are Arranged by 45 °. Examples of the polarizers 11 and 11 'include polarizing glass. Polarized glass is a member having polarization characteristics by arranging metal particles elongated in the glass in one direction, and transmits light having a polarization direction perpendicular to the extending direction of the metal particles. Absorbs light having a polarization direction parallel to the stretching direction. As the glass for forming the polarizers 11 and 11 ', for example, a glass in which a metal is contained in a borosilicate glass can be used. Further, examples of the shape of the polarizers 11 and 11 ′ include various shapes such as a flat plate shape, a disk shape, and a wedge shape.

  One of the pair of light entrance / exit surfaces of the optical isolator element 10 is the back surface (11a) of the surface bonded to the Faraday rotator 12 of the polarizer 11, and the other is on the cylindrical body 32 side of the polarizer 11 ′. Refers to the surface (11'a) that is located. The bottom surface of the optical isolator element 10 is located between the light incident / exiting surface 11a and the light incident / exiting surface 11′a, and the side surfaces of the polarizer 11, the Faraday rotator 12, and the polarizer 11 ′ are the same. The surface (10a) which exists on a plane is pointed out. The light entrance / exit surfaces 11a and 11′a of the optical isolator element 10 have a predetermined size that is sufficiently larger than the beam spot diameter of the incident light and also takes into account the optical axis deviation from the optical fiber 31, and the bottom surface 10a. Is formed so as to have the same angle as the angle of the one end face 32 b of the cylindrical body 32.

  The optical isolator 20 includes an optical isolator element 10 and a cylindrical magnet 21 for applying a magnetic field to the Faraday rotator 12 of the optical isolator element 10. The magnet 21 is inserted and fixed to the outer peripheral portion of the cylindrical body 32 of the optical fiber terminal 30 so as to cover the optical isolator element 10. In this embodiment, the magnet 21 is bonded and fixed to the cylindrical body 32, but may be fixed by press-fitting from the viewpoint of improving reliability in a high-temperature and high-humidity environment. Moreover, as a material of the magnet 21, Sm-Co etc. can be used, for example.

  The optical fiber terminal 30 includes an optical fiber 31, a cylindrical body 32, and a holder 33.

  The optical fiber 31 is a member for transmitting light. For example, an optical fiber such as a single mode fiber or a multimode fiber can be used, and the optical fiber 31 can be appropriately changed according to the application.

  The cylindrical body 32 is a member that has a through-hole 32a and holds one end of the through-hole 32a from which the coating of the optical fiber 31 has been removed via an adhesive. Examples of the material of the cylindrical body 32 include, for example, 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. Among these, zirconia-based ceramics (ceramics mainly composed of zirconia) having excellent weather resistance and toughness are preferable. The cylindrical body 32 has a support portion 32c that protrudes from one end surface 32b that opens at one end of the through hole 32a. The optical isolator element 10 is fixed on the upper surface 32d of the support portion 32c so that the light incident / exit surface 11'a of the polarizer 11 'faces the one end surface 32b. Specifically, the bottom surface 10a and the top surface 32d of the optical isolator element 10 are fixed through, for example, an epoxy adhesive.

  Thus, in the optical isolator module 40, the optical isolator element 10 can be supported by the upper surface 32d of the support portion 32c protruding from the one end surface 32b of the cylindrical body 32. As a result, in the optical isolator module 40, the optical isolator element 10 can be prevented from dropping from the cylindrical body 32, so that the reliability can be improved.

  Furthermore, in the optical isolator module 40, it is preferable that the light incident / exit surface 11'a of the polarizer 11 'of the optical isolator element 10 and the one end surface 32b of the cylindrical body 32 are fixed with a translucent adhesive. The translucent adhesive is a material that transmits a small loss of incident light, in other words, a refraction equivalent to the refractive index of the polarizers 11, 11 ′, the Faraday rotator 12, and the optical fiber 31. A translucent material having a ratio (for example, 1.45 to 1.57) may be used. For example, an epoxy or acrylic translucent material can be suitably used. In this way, if the light incident / exit surface 11′a of the polarizer 11 ′ of the optical isolator element 10 and the one end surface 32b of the cylindrical body 32 are fixed with a light-transmitting adhesive, the optical isolator element 10 is cylindrical. While being able to be firmly fixed to the state body 32 and loss of light in the adhesive can be reduced, reliability can be further improved. Furthermore, in the optical isolator module 40, if the one end surface 32b of the cylindrical body 32 is an inclined surface that is inclined with respect to the direction orthogonal to the axial direction of the through hole 32a, the influence of reflected return light on the light emitting element such as an LD. Can be suppressed. The inclination angle of the one end surface 32b of the cylindrical body 32 is inclined by 4 to 8 ° with respect to the surface orthogonal to the axial direction of the through hole 32a.

  As shown in FIG. 1, the support portion 32 c preferably protrudes in the same direction as the longitudinal direction (axial direction) of the cylindrical body 32. As described above, when the cylindrical body 32 is projected (extended) in the same direction as the longitudinal direction, both the light incident / exit surface 11 ′ and the bottom surface 10 a of the optical isolator element 10 are easily fixed to the cylindrical body 32. can do. In addition, the support portion 32c may be configured by joining another member to the one end surface 32b of the cylindrical body 32, but it is more integrally formed with the cylindrical body 32 from the viewpoint of cost reduction. Is preferred. And if it is such a support part 32c, it will be about 0.5-1.5 mm from the one end surface 32b of the cylindrical body 32 to the axial direction of the cylindrical body 32, and the through-hole 32a in the direction orthogonal to an axial direction, for example. It can be easily formed by cutting out to a deeper position.

  The holder 33 is a member for holding the cylindrical body 32 in the first through hole 33a and fixing the covering portion 31a of the optical fiber 31 in the second through hole 33b communicating with the first through hole 33a. It has a shape. The cylindrical body 32 is press-fitted into the first through hole 33a. The holder 33 can be formed of a metal member such as stainless steel.

  Next, another embodiment of the optical isolator module of the present invention will be described with reference to FIG. 2A and 2B show another embodiment of the optical isolator module of the present invention, in which FIG. 2A is a side perspective view, and FIG. 2B is the vicinity of the end face of a cylindrical body to which the optical isolator element of FIG. FIG. Moreover, FIG.2 (c) is the elements on larger scale which show the modification of the site | part shown in (b).

  The optical isolator module 40 ′ is different from the optical isolator module 40 in that the optical isolator module 40 ′ has a pair of wall portions 32 f extending from the one end surface 32 b of the cylindrical body 32 so as to face the side surface 10 b of the optical isolator element 10. As shown in FIG. 2B, the cylindrical body 32 has an end portion of the cylindrical body 32 that is larger than the through hole 32 a so that the width of the support portion 32 c is slightly larger than the width of the optical isolator element 10. A pair of wall portions 32f are formed on both sides of the optical isolator element 10 by cutting out to a deep position by dicing or the like. Thus, if the wall part 32f is formed by notching the end part of the cylindrical body 32, it can be formed integrally with the cylindrical body 32, so that the mechanical strength can be increased. The optical isolator element 10 is bonded and fixed to the support portion 32c and the four surfaces of the one end surface 32b and the wall portion 32f. The adhesive may be the same on all four surfaces. If the optical isolator 10 is installed by applying it to the support portion 32c and the one end surface 32b of the cylindrical body 32, the adhesive is bonded between the side surface of the optical isolator and the wall portion 32f. The agent is filled by scooping up. Since the optical isolator module 40 ′ has the pair of wall portions 32f, the optical isolator element 10 can be positioned more accurately and the bonding area between the optical isolator element 10 and the cylindrical body 32 can be increased. can do.

  Further, as shown in FIG. 2B, the optical isolator module 40 ′ extends until the wall portion 32f completely covers the side surface of the optical isolator element, but the present invention is limited to such a form. In addition, as long as the structure of the optical isolator element 10 is easy to position, only a part of the side surface of the optical isolator element 10 may be covered. For example, in FIG. 2C, the wall portion 32f extends only to a part of the side surface of the Faraday rotator 12 and the side surface of the polarizer 11 ′. The optical isolator element 10 can be positioned by matching the position with the wall portion 32f.

FIG. 3 is an enlarged perspective view of a fiber stub 50 with an optical isolator element, which is another embodiment of the optical isolator module. The fiber stub 50 with the optical isolator element is different from the optical isolator module 40 in that the optical fiber 31 is completely accommodated in the cylindrical body 32. The fiber stub 50 with an optical isolator element can be incorporated into an optical component such as an optical receptacle, for example, by using the other end surface 32e of the cylindrical body 32 as an optical polishing surface.

  FIG. 4 is a longitudinal sectional view showing an embodiment of the optical element module of the present invention. An optical element module 70 according to an embodiment of the present invention includes an optical unit 60 including a light emitting element 61 such as an LD, a lens 62, a stem 63, and an electronic cooling element 64, a case 71 that houses the optical unit 60, and an optical isolator. The module 40 and a holding member 72 (second holder) that holds the optical isolator module 40 are provided. Note that the monitor PD (photodiode) and wiring lead wires built in the case 71 are omitted.

  In the optical unit 60, the light emitting element 61 is mounted and fixed on the stem 63 by soldering, the lens 62 for condensing the light emitted from the light emitting element 61 is mounted on the stem 63 by solder or YAG laser, and the stem 63 is mounted on the electronic cooling element. It is formed by mounting and fixing on 64 with solder. The optical unit 60 is accommodated in a case 71 and fixed with solder or the like. Further, the optical isolator module 40 is inserted into the holding member 72 so that the flange portion 72a of the holding member 72 faces the pipe member 71a made of stainless steel or Fe—Ni material provided in the case 71. Finally, after adjusting the optical isolator module 40 in the XYZ directions with respect to the optical axis of the light emitted from the optical unit 60, the flange portion 72a of the holding member 72 is used as the pipe member 71a, and the holder 33 of the optical isolator module 40 ( The optical element module 70 is completed by welding the first holder) to the holding member 72 (second holder) with a YAG laser. Thus, since the optical element module 70 includes the optical isolator module of the present invention, it is possible to prevent the optical isolator element 10 from dropping from the cylindrical body 32, and thus the reliability can be improved.

  In the present embodiment, an example of an optical isolator module and an optical element module having an optical fiber has been described. However, the present invention is not limited to such a form, and for example, a tubular body is penetrated instead of an optical fiber. The hole may be filled with a translucent member, or may simply be configured to transmit light through a through hole.

  Hereinafter, an optical isolator module 40 was produced as an example of the present invention.

<Fabrication of optical fiber terminal>
First, the cylindrical body 32 made of zirconia ceramics having a through hole 32a at the center was press-fitted and fixed to one end side of the first through hole 33a of the holder 33 made of stainless steel. Next, the optical fiber 31 is inserted into the second through hole 33 b of the holder 33, and the tip of the optical fiber 31 from which the coating has been removed is fixed in the through hole 32 a of the cylindrical body 32 with an adhesive, The covering portion 31a of the optical fiber 31 was fixed to the second through hole 33b with an adhesive. Note that the cylindrical body 32 has an end surface of about 0.6 mm in the axial direction of the cylindrical body, and more than the central portion of the first through hole 33a through which the optical fiber 31 is inserted in the direction orthogonal to the axial direction. The support part 33c was provided by cutting out to a position about 0.2 mm deep. The one end surface 32b of the cylindrical body 32 was set so as to be inclined by 4 ° with respect to the surface orthogonal to the through hole 32a. Thereby, an optical fiber terminal was formed.

<Production of optical isolator element>
First, after rotating and aligning the angles of the transmission polarization planes of the two polarizers 11 and 11 ′ to be 45 °, Faraday rotation is performed using a light-transmitting adhesive between the polarizers 11 and 11 ′. The child 12 was stuck and fixed. The light incident / exit surfaces of the polarizers 11, 11 ′ are about 0.4 mm long × about 0.4 mm wide = about 0.16 mm ^{2 in} the direction of the optical axis for forming the bottom surface 10 a of the optical isolator element 10. This angle was cut to 4 °, which is the same as the angle of the one end face 32b of the cylindrical body 32. Since the two polarizers 11, 11 ′ and the Faraday rotator 12 are both about 0.2 mm in thickness, the area of the bottom surface 10 a of the optical isolator element 10 is about 0.4 mm in width × about 0 in thickness. .6Mm = about 0.24 mm ^2, is about 0.4 mm ² in conjunction with the input-output face of the light.

<Assembly of optical isolator module>
The light exit surface of the polarizer 11 ′ of the optical isolator element 10 is fixed to the one end surface 32 b of the cylindrical body 32 with a translucent epoxy adhesive having a refractive index of about 1.5 which is substantially the same as that of the optical fiber 31. On the other hand, the bottom surface 10a of the optical isolator element 10 was fixed to the upper surface 32d of the support portion 32c of the cylindrical body 32 with an epoxy adhesive. Finally, the optical isolator module 40 was manufactured by inserting and fixing the magnet 21 to the outer periphery of the cylindrical body 32 so as to cover the optical isolator element 10. In the optical isolator module 40 shown in the present embodiment, it is about 2.5 times as large as the bonding area (about 0.16 mm ² ) bonded only on the emission surface of the conventional optical isolator element 100 shown in FIG. Adhesive area is obtained.

Then, a high-temperature and high-humidity cycle test was performed on the optical isolator module according to the embodiment of the present invention and the conventional optical isolator module, and the deterioration of the adhesive strength was verified. Specifically, 20 samples each configured according to the present invention and samples configured according to the prior art are prepared,
The deterioration of the adhesive strength between the optical isolator element and the cylindrical body after being left for 2000 hours in an environment with an ambient temperature of 85 ° C. and a humidity of 85% was verified. The adhesive strength is a measured value when the adhesive portion with the cylindrical body is peeled off by pressing from the side surface of the isolator element using a push-pull gauge.

  According to this result, in the optical isolator module according to the embodiment of the present invention, the adhesive area between the optical isolator element and the cylindrical body can be increased by about 2.5 times compared to the conventional example. Can be increased by 2.7 to 2.8 times. Moreover, even after the test, it was possible to obtain an adhesive strength of 2.5 times or more as compared with the conventional example.

It is a longitudinal cross-sectional view which shows an example of embodiment of the optical isolator module of this invention. The other example of embodiment of the optical isolator module of this invention is shown, (a) is side perspective drawing, (b) is the elements on larger scale in the edge part of a cylindrical body, (c) is (b). It is the elements on larger scale of a modification. It is an expansion perspective view which shows the optical isolator element and cylindrical body of an example of embodiment of the optical isolator module of this invention. It is a longitudinal cross-sectional view which shows an example of the optical element module of this invention. It is a longitudinal cross-sectional view which shows the conventional optical isolator module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical isolator element 10a ... Bottom face 11, 11 'of optical isolator element ... Polarizer 12 ... Faraday rotator 20 ... Optical isolator part 21 ... Magnet 30 ... Optical fiber terminal 31 ... Optical fiber 31a ... Belly part 32 of optical fiber ... Cylindrical body 32a ... Through hole 32b ... One end surface 32c of the cylindrical body ... Support portion 32d ... Upper surface 32e of the support portion ... Other end surface 32f of the cylindrical body ... Wall portion 33 ... Holder (first holder)
33a ... 1st through-hole 33b ... 2nd through-hole 40, 40 '... Optical isolator module 50 ... Fiber stub 60 with optical isolator ... Optical unit 61 ... Light emitting element 62 ... Lens 63 ... Stem 64 ... Electronic cooling element 70 ... Optical element Module 71 ... Case 71a ... Case pipe 72 ... Holding member (second holder)
72a ... Flange of holding member

Claims (9)

An optical isolator element having a pair of opposing light incident / exit surfaces, a pair of side surfaces located in a direction intersecting with the pair of light incident / exit surfaces, and a bottom surface located between the pair of light incident / exit surfaces;
A cylindrical body arranged so that one end surface opened on one end side of the through-hole through which light is transmitted is opposed to one of the light incident / exit surfaces;
The cylindrical body has a support portion extending from one end surface, and the optical isolator element is fixed to the support portion at the bottom surface.   2. The optical isolator module according to claim 1, wherein one of the light incident / exit surfaces of the optical isolator element is fixed to an end surface of the cylindrical body with a light-transmitting adhesive.   The optical isolator module according to claim 1, wherein the support portion protrudes in the same direction as a longitudinal direction of the cylindrical body.   The optical isolator module according to claim 1, wherein one end surface of the cylindrical body is an inclined surface that is inclined with respect to a direction orthogonal to the axial direction of the through hole.   The optical isolator module according to claim 1, wherein the support portion is formed integrally with the cylindrical body.   The cylindrical body has a pair of wall portions extending from one end surface so as to face the side surface of the optical isolator element, and the side surface of the optical isolator element is fixed to the wall portion by the adhesive. The optical isolator module according to claim 1, wherein the optical isolator module is an optical isolator module.   The optical isolator module according to claim 6, wherein the wall portion is formed integrally with the cylindrical body.   The optical isolator element includes two polarizers each having the light incident surface, a Faraday rotator disposed between the two polarizers, and at least the Faraday rotator so as to cover the cylindrical body. An optical isolator module according to claim 1, comprising an optical isolator comprising: a cylindrical magnet inserted in an outer peripheral portion of one end portion. The optical isolator module according to any one of claims 1 to 8,
A cylindrical first holder in which one end of the cylindrical body is inserted and fixed;
A second holder in which the first holder is inserted;
A light-emitting element that transmits light toward the through hole of the cylindrical body via the optical isolator element;
An optical element module comprising a case that houses the light emitting element and is joined to the second holder.

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