JP2007199558A - Optical device and optical module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that size of a ferrule and the size of a lens are large and downsizing is difficult in an optical module such as an optical multiplexer/demultiplexer of the conventional constitution. <P>SOLUTION: The optical device is provided with: at least two optical fibers optically coupled to each other; an optical element 13 arranged between the optical fibers; and a light-transmitting member 14 which is interposed between the optical element 13 and the end part of the optical fiber, is spliced to the end part of the optical fiber by fusion and supports the optical element 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes an optical isolator having optical elements such as an optical isolator and an optical filter and having two or more optical fibers that input and output light, and a plurality of lights having different wavelengths are multiplexed or demultiplexed. The present invention relates to an optical device such as an optical multiplexer / demultiplexer, and an optical module including such an optical device.

  In recent years, with the increase in information capacity, the introduction of optical communication transmission devices has progressed, and the demand for optical modules such as optical isolators and optical multiplexers / demultiplexers used in optical communication transmission devices has increased. Here, a typical configuration of a conventional optical multiplexer / demultiplexer is shown in FIG. 7 (see, for example, Patent Document 1).

  The optical multiplexer / demultiplexer 31 shown in FIG. 7 includes an optical fiber 32, a two-core ferrule 35 that holds the optical fiber 33, a one-core ferrule 37 that holds the optical fiber 34, and a two-core ferrule 35 and a one-core ferrule 37. And an optical filter 38 and two lenses 36a and 36b arranged between the optical filter 38 and both ferrules. The optical multiplexer / demultiplexer has a function of demultiplexing light having a plurality of different wavelength bands incident on a single optical fiber into a plurality of optical fibers according to the wavelength bands, or light having different wavelength bands. It has a function of combining light emitted from a plurality of incident optical fibers by entering the light into a single optical fiber.

  With this optical multiplexer / demultiplexer 31, for example, when light λ1 and λ2 having two different wavelengths are incident on the optical fiber 32, the light λ1 and λ2 emitted from the optical fiber 2 are first incident on the lens 36a. . Since the lenses 36a and 36b have a function of converting the emitted light into parallel light, the light emitted from the lens 36a is incident on the optical filter 38 with its optical path bent. Here, since the optical filter 38 has a characteristic of transmitting the light with the wavelength λ1 and reflecting the light with the wavelength λ2, the light having the wavelength λ1 among the light emitted from the lens 36a is used. Is transmitted, and light of wavelength λ2 is reflected. Then, the light of wavelength λ2 reflected by the optical filter 38 is incident again on the lens 36a, is incident on the optical fiber 33 through the lens 36a, and the light of wavelength λ1 transmitted through the optical filter 38 is transmitted by the lens 36b. The light is collected and incident on the optical fiber 34. As described above, the optical multiplexer / demultiplexer 31 has a function as an optical demultiplexer that separates light having different wavelengths of λ1 and λ2 that has entered the optical fiber 32 into separate optical fibers. By reversing the input / output of light, that is, by combining the light beams λ1 and λ2 incident on the optical fibers 33 and 34 and entering the optical fiber 22, the optical fiber 22 functions as an optical multiplexer.

As another form of the optical multiplexer / demultiplexer, as shown in FIG. 8, a groove branched in a plurality of directions is formed on the substrate 49, and the optical fibers 42, 43, 44 are formed in the groove. The optical filter 48 is mounted in a groove formed at the intersection of the grooves and bonded and fixed with a translucent resin (see, for example, Patent Document 2). In this optical multiplexer / demultiplexer 41, when light having two wavelengths λ 1 and λ 2 is incident on the optical fiber 42, the light λ 2 reflected by the optical filter 48 is incident on the optical fiber 43. Since the transmitted light λ1 is incident on the optical fiber 44, it has the same function as the optical multiplexer / demultiplexer shown in FIG.
JP-A-8-271760 Japanese Patent Laid-Open No. 2-100005

  However, the optical device configured as the optical multiplexer / demultiplexer 31 has a problem that it is difficult to reduce the size of the device because the size of the ferrule and the lens is large. In addition, when the optical multiplexer / demultiplexer 31 is designed to have a small lens size in order to reduce its size, the interval between adjacent optical fibers is also narrowed. There is a problem that light leaks into the adjacent optical fiber slightly and enters, and the isolation characteristics deteriorate. Furthermore, in such an optical multiplexer / demultiplexer, light transmitted or reflected by the optical filter must be efficiently incident on each optical fiber, and components such as the lens, optical fiber, and optical filter are precisely aligned. Therefore, mass production is difficult.

  Further, in an optical device having a configuration such as the optical multiplexer / demultiplexer 41, the optical fiber 42, 43, 44 is mounted in a groove formed on the substrate 48 via an adhesive, so that the substrate 48 is indispensable. It is necessary to enlarge the substrate 48 according to the length of the optical fibers 42, 43, and 44, and it is difficult to reduce the size of the device. Further, when the optical multiplexer / demultiplexer 41 is used in a specification that requires a high low loss of light, a lens for condensing the light emitted from the optical fiber is not used, so that the light is emitted from the optical fiber 42. In the optical system in which the transmitted light passes through the optical filter 48 and is coupled to the optical fiber 44, the beam diameter of the light is widened due to the thickness of the optical filter 48, so that the coupling loss of the light between the optical fibers is large. In the optical system in which the light emitted from the fiber 42 is reflected by the optical filter 48 and coupled to the optical fiber 43, there is a problem that the loss of light increases because the beam spreads by the thickness of the cladding diameter of the optical fiber itself. .

  The present invention has been made in view of the above problems, and an optical device of the present invention includes at least two optical fibers that are optically coupled, an optical element disposed between the optical fibers, and the optical element. And a translucent member that supports the optical element while being fused and connected to the end of the optical fiber.

  Moreover, in this invention, the edge part which faces the said optical element of the said optical fiber is melt-connected by the inside of the said translucent member, It is characterized by the above-mentioned.

  Moreover, in this invention, the site | part connected continuously with the surrounding surface of the edge part which faces the said optical element of the said optical fiber of the said translucent member is circular arc shape, It is characterized by the above-mentioned.

  In the present invention, the translucent member is provided with a recess having a bottom surface for supporting the optical element.

  In the present invention, the optical fiber includes a graded index fiber joined to an end facing the optical element.

  In the present invention, the optical fiber includes a coreless fiber joined to an end of the graded index fiber facing the optical element.

  In the present invention, the optical element is an isolator element including a Faraday rotator that rotates a polarization plane of incident light.

  In the present invention, the optical element is an optical filter for multiplexing and / or demultiplexing incident light.

  The optical module of the present invention includes a light emitting element, the optical device in which light emitted from the light emitting element is incident on one optical fiber, and light is emitted from the other optical fiber, and the optical device. A light receiving element for receiving the emitted light.

  According to the configuration of the present invention, at least two optical fibers that are optically coupled, an optical element disposed between the optical fibers, and the optical element and an end of the optical fiber are interposed. And a translucent member that supports the optical element while being fused and connected to the end of the optical fiber. As a result, in the optical device of the present invention, since the translucent member and the optical fiber are fixed by fusion splicing, a holding member that holds the optical fiber is not essential, and the miniaturization of components is realized. it can.

  In the optical device of the present invention, it is preferable that an end of the optical fiber facing the optical element is fusion-bonded to the inside of the translucent member. According to such a configuration, since the surface area of the optical fiber in contact with the translucent member can be increased, the optical fiber and the translucent member can be more firmly connected.

  Moreover, in the optical device of this invention, it is preferable that the site | part connected continuously with the surrounding surface of the edge part which faces the said optical element of the said optical fiber of the said translucent member is circular arc shape. According to such a configuration, for example, even if stress such as bending or pulling acts on the optical fiber from the outside, stress concentration generated at the connection portion between the optical fiber and the translucent member can be reduced. Therefore, the crack etc. which generate | occur | produce in the said connection site | part can be suppressed.

  In the optical device of the present invention, it is preferable that a concave portion having a bottom surface portion for supporting the optical element is provided in the translucent member. According to such a configuration, since the optical element can be easily mounted and the mounting area is increased, the optical element can be more firmly fixed to the translucent member.

  In the optical device of the present invention, it is preferable that the optical fiber includes a graded index fiber at an end facing the optical element. With such a configuration, the optical effect can be adjusted without using a conventional lens while adjusting the optical path length in the translucent member to maintain the optimum optical coupling state by the lens effect of the great index fiber. This makes it possible to reduce the size of parts.

  Furthermore, in the optical device of the present invention, by providing a coreless fiber at the end of the graded index fiber facing the optical element, for example, even when the optical path length is designed to be long, the translucent member is made as small as possible. Since the thickness can be set, it is possible to reduce the loss of light generated in the translucent member.

  Hereinafter, the optical device of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing a first embodiment of an optical multiplexer / demultiplexer which is a kind of optical device of the present invention. An optical multiplexer / demultiplexer 100 according to the first embodiment of the present invention includes an optical fiber 17a in which single mode fibers 10a, 10b, and 10c, graded index fibers 11a, 11b, and 11c, and coreless fibers 12a, 12b, and 12c are joined. , 17b, 17c, and an optical filter 13 (corresponding to an optical element) in which an optical thin film 13b is formed on a support substrate 13a, and a translucent member 14.

  Each of the single mode fibers 10a, 10b, and 10c includes a core portion having a high refractive index and a clad portion that covers the outer periphery of the core portion, and uses the reflection due to the difference in refractive index at the interface between the core portion and the clad portion to The light is transmitted within the part, and is made of, for example, cylindrical quartz or the like, and has an outer diameter of the cladding part of, for example, about 125 μm and a core part of about 10 μm.

  The graded index fibers 11a, 11b, and 11c are fibers having an approximately square refractive index distribution in the axial symmetry, and can be used as a gradient index lens, so that they are emitted from the optical fibers 17a, 17b, and 17c. Or has a function of collecting or collimating incident light. The graded index fibers 11a, 11b, and 11c are made of, for example, columnar quartz or the like, and the outer diameter of the cladding portion is, for example, about 125 μm (equivalent to the single mode fiber described above), and the core portion has a diameter of about 50 μm. The core portion has the above refractive index profile. The graded index fibers 11a, 11b, and 11c and the single mode fibers 10a, 10b, and 10c are positioned so that the centers of the fibers coincide with each other, and then fused by heat such as arc discharge. Be joined.

The coreless fibers 15a, 15b, and 15c are fibers having a substantially uniform refractive index distribution, and the material thereof is made of, for example, quartz glass, the refractive index is about 1.45, and the light transmission loss is 0.25 × 10 ^−6. It is preferably equal to or less than dB / mm and thus has a relatively low light transmission loss. The coreless fibers 15a, 15b, and 15c have an outer diameter equal to that of the optical fiber (single mode fiber) and the graded index fiber, which is about 125 μm. For example, after adjusting the positions so that the centers of the respective fibers coincide with each other, the fibers are joined by heat fusion such as arc discharge, and are produced as optical fibers 17a, 17b, and 17c, respectively.

  In the optical filter 13, for example, an optical thin film 13b is provided on one main surface of a translucent support substrate 13a. The optical thin film 13b transmits light including light of a plurality of different wavelength regions for each wavelength region. Have a function of selectively separating (demultiplexing). Specifically, the optical filter 11 reflects light in one wavelength region and demultiplexes light for each wavelength region by transmitting light in the other wavelength region, that is, reflects light in a predetermined wavelength region. It has the function to do. In the first embodiment of the present invention, the optical filter 13 is incident on the single mode fiber 10a (see the solid line arrow in FIG. 1A) and is emitted from the two wavelength regions λ1 and λ2 emitted from the coreless fiber 12a. Is transmitted through one wavelength region λ1 and incident on the coreless fiber 12b, while the other wavelength region λ2 is reflected to be incident on the coreless fiber 12c. Can wave. In the first embodiment of the present invention, when the input / output of light is reversed (see the dotted arrows in FIG. 1A), the light incident on the optical fibers 10b and 10c passes through the optical filter 13. Can be made incident on the optical fiber 10a.

  The support substrate 13a constituting a part of the optical filter 13 is translucent and 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 1.55. Is used. Moreover, the size should just be beyond the effective diameter of light, for example, 0.5 mm square and thickness are 0.3 mm. The optical thin film 13b constituting a part of the optical filter 13 is a multilayer film formed 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 repetitive reflection interference between the dielectric films, and its film thickness is set to ¼ wavelength of the wavelength of light to be reflected. In this way, by setting the thickness of the dielectric film to ¼ wavelength, the phase of the light of a specific wavelength is matched in the multiple reflection at each dielectric film interface, and is strengthened by interference. A wavelength selective filter is realized. And in this optical filter 13, since the optical thin film 13b is formed in the surface of the support substrate 13a, the optical thin film 13b is easily produced by methods, such as vapor deposition and sputtering, on one main surface of the support substrate 13a, for example. Can do. In addition, although the optical filter 13 mentioned above is the structure by which the optical thin film 13b was formed in one main surface of the support substrate 13a, in this invention, it is not limited to the form mentioned above, for example, the optical thin film 13b is There may be a configuration in which the optical thin film 13b is disposed in a translucent substrate or a configuration in which the support substrate 13a is sandwiched between two substrates.

  The translucent member 14 is disposed between the coreless fibers 15a, 15b, 15c and the optical filter 13, and has a function of supporting the optical filter 13 and fixing the optical fibers 17a, 17b, 17c connected by fusion. Have. The material of the translucent member 14 is, for example, an optical glass having a melting point lower than that of quartz glass (melting point: 1700 to 1800 ° C.) mainly constituting the core part and the cladding part of the optical fiber, for example, borosilicate glass (melting point: 500 to 700 ° C.) and white glass (melting point: 500 to 700 ° C.). The refractive index is preferably about 1.45 to 1.55, which is equivalent to the refractive index of the optical fiber to be spliced. .

  The shape of the translucent member 14 is not particularly limited as long as the optical fiber that supports the optical filter 13 and the fusion-spliced optical fibers can be optically coupled via the optical filter 13. As shown in FIG. 1 (a), the shape may be a shape that is gripped from both sides of the optical filter 13, but the outer shape may be a circular or polygonal frame shape, etc. The shape which provided the recessed part in a part of a shape or a spherical form may be sufficient.

  In the present invention, the light transmissive member 14 is supported by the light transmissive member 14 and the light transmissive member 14 and the light filter 13 are interposed between the light transmissive member 14 and the light filter 13 to prevent light reflection. It is preferable to fill an optical adhesive (not shown) whose refractive index is matched. As the optical adhesive, a material such as an epoxy resin, an acrylic resin, or a silicon resin having light permeability can be used. Note that the epoxy resin, the silicon resin, and the acrylic resin are ultraviolet-cured or heat-cured by their additives, and these combined curing may be used.

  As a manufacturing method of this translucent member 14, for example, if it is made of borosilicate glass, it is manufactured by finishing it into a desired shape by dicing or the like.

  Further, the translucent member 14 is such that the attenuation (loss) of light per 1 cm of the translucent member with respect to light of a wavelength to be used (for example, 1550 nm) is 6 dB or less with respect to the amount of light input. . Preferably 3 dB or less is preferably used, and optimally 0.5 dB or less. Furthermore, as a method for measuring the amount of attenuation of light, light from a light source (for example, LED or LD) is converted into a parallel beam through a lens, arranged so as to pass through the translucent member 14, and emitted from the back surface. Measure the amount of light with a power meter. The amount of light attenuation is calculated from the ratio of the amounts of light obtained by this measurement. At this time, the reflection loss on the front and back surfaces is included and measured by the refractive index of the transparent member 14.

  Optical fibers 17a, 17b, and 17c are fused and connected to the translucent member 14, respectively. This fusion splicing is arranged at a position where the translucent member 14 and the optical fiber are connected to each other, and at least one of the translucent member 14 or the optical fibers 17a, 17b, and 17c is melted by, for example, arc discharge or laser. Then, it is cooled and connected. Since such fusion splicing can be performed more firmly than adhesion using a resin-based adhesive, a substrate for holding the optical fibers 17a, 17b, and 17c is not essential. Further, for example, even if an external force is applied to the optical fibers 17a, 17b, and 17c, the optical fibers 17a, 17b, and 17c can be prevented from dropping from the translucent member 14.

  As described above, in the present invention, since the optical fibers 17a, 17b, and 17c are fused and connected directly to the translucent member 14, a substrate for holding the optical fibers 17a, 17b, and 17c is not essential. Disappear. Therefore, in the present invention, it is possible to easily realize the miniaturization of parts.

  Further, as shown in FIG. 1B, the end portions of the optical fibers 17a, 17b, and 17c that face the optical filter 13, that is, the coreless fibers 15a, 15b, and 15c are fused and connected inside the translucent member 14. It is preferable. According to such a configuration, since the surface areas of the optical fibers 17a, 17b, and 17c that are in contact with the translucent member 14 can be increased, the optical fibers 17a, 17b, and 17c and the translucent member 14 can be further strengthened. Can be connected to.

Further, as shown in FIG. 1 (b), the end portions of the light transmissive member 14 facing the optical elements of the optical fibers 17a, 17b, and 17c, that is, the peripheral surfaces of the coreless fibers 15a, 15b, and 15c are connected continuously. It is preferable that the site | part 14a currently made is circular arc shape. According to such a configuration, even if a stress such as bending or pulling acts on the optical fibers 17a, 17b, and 17c from the outside, for example, the connection site between the optical fibers 17a, 17b, and 17c and the translucent member 14 Since the stress concentration occurring in the connection can be alleviated, cracks and the like generated in the connection part can be suppressed. Next, a method for manufacturing the optical multiplexer / demultiplexer according to the first embodiment of the present invention will be described.

  First, the optical fibers 17a and 17c are held by a fixing jig so that the light emitted from each of the optical fibers 17a and 17c forms an intersection. For example, when two light-transmitting members 14 having a flat plate shape are used, After the optical fibers 17a and 17c are applied to the side surfaces, the optical fibers 17a and 17c are applied to the translucent member 14 while the contact surfaces are heated in a short time by arc discharge or laser. insert. At this time, the design position is set slightly inward with respect to the abutting surface, and is inserted deeper than the design position at the time of initial insertion, and the optical fibers 17a and 17c are pulled back to the design position during heating. At the same time, the interface between the optical fibers 17a and 17c and the translucent member 14 can be formed in an arc shape. During the melting and heating, the translucent member 14 is melted to locally deform the translucent member 14, and the dimension in the thickness direction serving as an optical path changes. It is necessary to anticipate the amount of correction according to conditions. Next, the optical fiber 17b is fused to the other translucent member 14 at a position that is in line with the optical fiber 17a. Finally, the optical filter 13 is pasted between two translucent members 14 via an optical adhesive (not shown) whose refractive index is matched. At this time, light of λ1 and λ2 is introduced into the optical fiber 10a, and the output ends of the optical fiber 17b and the optical fiber 17c are measured with a power meter or the like, and the respective optical outputs are maximized. After the adjustment, the optical multiplexer / demultiplexer 100 is manufactured by curing the optical adhesive. At this time, since some optical adhesives shrink during curing, a positional deviation occurs. Therefore, it is preferable to make the structure as thin as possible, and it is also possible to make a positional deviation by finely adjusting the position until it is completely cured. Can be prevented. Note that the support substrate 13 a can also be used as one of the translucent members 14.

  Hereinafter, another embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the element and member similar to the optical demultiplexer 1 demonstrated previously with reference to FIG. 1, and duplication description is abbreviate | omitted.

  FIG. 2 is a perspective view showing a second embodiment of the optical device (optical multiplexer / demultiplexer) of the present invention. In the optical multiplexer / demultiplexer 200 according to the second embodiment of the present invention, the optical multiplexer / demultiplexer is provided in that a concave portion 14b having a bottom surface portion for supporting the optical filter 13 is provided in a part of the translucent member 14. Different from corrugator 100. Other configurations of the optical multiplexer / demultiplexer 200 are the same as those described above regarding the optical multiplexer / demultiplexer 100. According to such a configuration, the optical filter 13 can be easily mounted and the mounting area is increased, so that the optical filter 13 can be more firmly fixed to the translucent member 14.

  Such a recess 14b of the translucent member 14 can be processed by, for example, dicing when the translucent member 14 is made of borosilicate glass. At this time, since the side surface of the optical fiber of the recess 14b becomes an optical surface, it is desirable that the surface roughness of the side surface is reduced to 1 μm or less by dicing or grinding.

  Further, when the optical filter 13 is disposed in the concave portion 14b, the optical adhesive described above is applied to one surface of the optical filter 13 and adhered to the side surface of the concave portion 14b, and the gap of the remaining concave portion 14b is elastically formed. If the structure is filled with a certain resin, it is possible to prevent the optical adhesive material from being peeled off due to thermal contraction during fixation or thermal expansion after completion.

    FIG. 3 is a plan view showing a third embodiment of the optical device (optical multiplexer / demultiplexer) of the present invention. In the optical multiplexer / demultiplexer 300 according to the third embodiment of the present invention, the optical multiplexer / demultiplexer 200 is provided in that the optical fibers 17a, 17b, 17c are arranged in parallel, and the optical filter 13 includes two optical thin films. And different. Other configurations of the optical multiplexer / demultiplexer 300 are the same as those described above regarding the optical multiplexer / demultiplexer 200. The optical filter 13 is configured such that the optical thin films 13b and 13c slightly overlap the front and back surfaces of the support substrate 13a. Such an optical filter 13 needs to be manufactured by, for example, forming the optical thin film 13b on a resin, melting the resin, and bonding the optical thin film 13b made of a dielectric multilayer film on the front and back of the support substrate 13a. According to such a configuration, since the optical fibers 17a, 17b, and 17c can be arranged close to each other in parallel, the components can be reduced in size. Furthermore, if the optical fibers 17a, 17b, and 17c are arranged in parallel as described above, it becomes easy to position and fuse these optical fibers together.

  FIG. 4 is a plan view showing a fourth embodiment of the optical device (optical multiplexer / demultiplexer) of the present invention. In the optical multiplexer / demultiplexer 400 according to the third embodiment of the present invention, the number of optical fibers of the optical multiplexer / demultiplexer 300 is increased to increase the number of channels. In the optical multiplexer / demultiplexer 400, a plurality of optical thin films 13b, 13d, 13e, and 13f are arranged on one surface of the support substrate 13a corresponding to the number of optical fibers, while one large thin film 13c is disposed on the opposite surface. The arranged optical filter 13 is used.

  At this time, the optical path lengths of the coreless fibers 12b, 12c, 12d, and 12e are adjusted to be substantially the same from the graded index fiber 11a, so that the tip positions of the optical fibers 17b, 17c, 17e, and 17d are the same. It is desirable to be adjusted to. This is because each optical fiber can be positioned and fused together.

  When an optical signal having four wavelengths λ1, λ2, λ3, and λ4 is input to the optical fiber 17a, the optical multiplexer / demultiplexer 400 passes through the optical thin film 13b and enters the optical fiber 10b. The wavelength λ2 is reflected in the order of the optical thin films 13b and 13c, passes through the optical thin film 13d and is incident on the optical fiber 17c, and the wavelength λ3 is reflected in the order of the optical thin films 13b, 13c, 13d, and 13c. The light passes through the thin film 13e and enters the optical fiber 10d, and the wavelength λ4 is reflected in the order of the optical thin films 13b, 13c, 13d, 13c, 13e, and 12c, passes through the optical thin film 13f, and enters the optical fiber 10e. It has a function to do.

  In the first to fourth embodiments of the present invention, the optical fiber 17 in which the coreless fiber 12 having the same diameter as the graded index fiber 11 is fused is used. The index fiber 11 may be fusion spliced, or only the single mode fiber 10 may be used without using the graded index fiber 11 depending on the application.

  FIG. 5 is a plan view showing an embodiment of an optical isolator which is a kind of optical device of the present invention.

  The optical isolator 500 uses an isolator element 18 (optical element) including a Faraday rotator having a magnet 19 disposed around it instead of the optical filter 13 disposed in the recess 14b of the translucent member 14. Thus, the optical multiplexer / demultiplexer 200 is different in configuration.

  In the optical isolator 500, the isolator element 18 is fixed in the recess 14b with a light-transmitting optical adhesive. The isolator element 18 is formed by stacking a first polarizer, a Faraday rotator, and a second polarizer and fixing each with a translucent resin, and transmits light in the forward direction (the arrow direction in FIG. 5). However, it has a function of blocking the transmission of light in the reverse direction.

  The first polarizer and the second polarizer have a function of transmitting a polarized light component in one direction of incident light and absorbing light of a component orthogonal thereto, and the polarizer is made of ellipsoidal metal particles. It consists of a polarizing glass having a structure dispersed in glass. This polarizing glass is a glass having polarization characteristics by arranging long stretched metal particles in one direction in the glass itself, light having a polarization plane perpendicular to the stretch direction of the metal particles is transmitted, Light with a parallel polarization plane is absorbed. This polarization characteristic is because the metal fine particles embedded in the dielectric exhibit light-plasma resonance.

The Faraday rotator is, for example, a bismuth-substituted garnet crystal, and its thickness is set so that the polarization plane of incident light having a predetermined wavelength rotates by 45 °. In order to rotate the plane of polarization, it is necessary to apply a sufficient magnetic field H in the direction of the optical axis Z of the incident light, and generally a permanent magnet (not shown) is often used. In addition, if the Faraday rotator has a very large magnetic hysteresis and does not have a magnet, a magnetic force-holding material that retains its own magnetic force, such as (TbBi) ₃ (FeAlGa) ₅ O _12, is not required. It becomes.

  The operation of the optical isolator 500 will be described below.

  As shown in FIG. 5, the light incident on the optical fiber 17 a is emitted from the end of the coreless fiber 12 a and is incident on the isolator element 18 via the translucent member 14. Of the light incident on the isolator element 18, the light in the polarization direction set in the first polarizer passes through the first polarizer. The light transmitted through the first polarizer is incident on the Faraday rotator, and is incident on the second polarizer with the polarization plane of the light rotated by 45 °. The second polarizer is arranged in advance so that the polarization direction thereof is at an angle of 45 ° with respect to the polarization direction of the first polarizer. Thereby, since the polarization direction of the light transmitted through the Faraday rotator coincides with the polarization direction of the second polarizer, the light passes through the second polarizer and enters the optical fiber 17b. On the other hand, the reflected light reflected by the difference in refractive index between the second polarizer and the Faraday rotator is incident on the Faraday rotator, so that the polarization direction is rotated by 45 °. Since the polarization direction of the reflected light transmitted through the Faraday rotator is shifted by 90 ° with respect to the polarization direction of the first polarizer, the reflected light is blocked at the surface of the first polarizer. Thus, the incidence on the optical fiber 17a is reduced. As described above, in the optical isolator 500, it is possible to suppress the light output fluctuation of the light source caused by the reflected light returning to the light source (not shown) that enters the optical fiber 17a.

  FIG. 6 is a plan view showing an embodiment of an optical module manufactured using an optical multiplexer / demultiplexer which is a kind of optical device of the present invention.

    In the optical module 600, laser diodes 20a to 20d (light emitting elements) for making light incident on the optical fibers 17b to 17e are disposed on the substrate 21 in the vicinity of the ends of the optical fibers 17b to 17e of the optical multiplexer / demultiplexer 400, respectively. It is an implemented configuration. In this laser diode, 20a to 20d are positioned on an electrode pattern formed by, for example, Au plating on a silicon substrate with high accuracy with reference to an electrode marker formed in advance on the substrate, and then applied to a gold-tin solder. It is fixed by heating. The silicon substrate 21 is formed with a V-groove for mounting a fiber on the basis of the electrode marker by, for example, an etching process, and the optical fibers 17b to 17e are mounted with high accuracy only by positioning against the V-groove. For example, the end of the optical fiber and the laser diode are sealed with an epoxy-based translucent resin. Such an optical module 600 efficiently combines light having different wavelengths emitted from the respective laser diodes into a single optical fiber 17a, and receives the combined light emitted from the optical fiber 17a as a light receiving element (not shown). ) Can be entered.

  In the above-described embodiment, the optical module for optical multiplexing has been described as an example. However, if the input / output of light is reversed, it has a function as an optical demultiplexer. Specifically, a light source such as a laser diode is disposed in the vicinity of the optical fiber 17a, and light having a plurality of different wavelength bands is incident from the light source, and the optical filter 13 according to the wavelength band to be demultiplexed. The optical thin film 13b may be set, and light receiving elements corresponding to the number of optical fibers may be arranged instead of the laser diodes 20a to 20d.

  According to the configuration of the optical module 600 of the present invention, a substrate for mounting a laser diode is required, but a substrate for holding the optical fiber 17a on the output side is not essential. However, it is possible to reduce the size of the parts. Further, in the optical module of the present invention, if the light emitting element and the light receiving element are mounted on different substrates, a substrate for holding the optical fiber constituting the optical device is not essential.

(A) is a top view which shows 1st Embodiment of the optical multiplexer / demultiplexer which is 1 type of the optical device of this invention, (b) is the elements on larger scale of (a). It is a perspective view which shows 2nd Embodiment of the optical multiplexer / demultiplexer which is 1 type of the optical device of this invention. It is a top view which shows 3rd Embodiment of the optical multiplexer / demultiplexer which is 1 type of the optical device of this invention. It is a top view which shows 4th Embodiment of the optical multiplexer / demultiplexer which is a kind of optical device of this invention. It is a top view which shows embodiment of the optical isolator which is 1 type of the optical device of this invention. It is a top view which shows an example of the optical module of this invention. It is a top view which shows an example of the conventional optical multiplexer / demultiplexer. It is a top view which shows an example of the conventional optical multiplexer / demultiplexer.

Explanation of symbols

17a to 17c, 32, 33, 34, 42, 43, 44: optical fibers 10a to 10e: single mode fibers 11a to 11e: graded index fibers 13a to 12e: coreless fiber 13: optical filter (optical element)
13a: Support substrate 13b: Optical thin film 14: Translucent member 14a: Recess 18: Isolator element (optical element)
19: Magnets 20a to 20d: Laser diode 35, 37: Ferrule 36a, 36b: Lens 31, 100, 200, 300, 400: Optical multiplexer / demultiplexer 500: Optical isolator 600: Optical module

Claims (9)

At least two optical fibers optically coupled; an optical element disposed between the optical fibers; and the end of the optical fiber interposed between the optical element and the end of the optical fiber And a light-transmitting member that supports the optical element. The optical device according to claim 1, wherein an end of the optical fiber facing the optical element is fusion-bonded to the inside of the translucent member. 3. The optical device according to claim 1, wherein a portion of the light transmissive member that is continuously connected to a peripheral surface of an end portion of the optical fiber facing the optical element has an arc shape. . The optical device according to any one of claims 1 to 3, wherein the translucent member is provided with a recess having a bottom surface for supporting the optical element. The optical device according to any one of claims 1 to 4, wherein the optical fiber includes a graded index fiber bonded to an end facing the optical element. The optical device according to claim 5, wherein the optical fiber includes a coreless fiber bonded to an end of the graded index fiber facing the optical element. The optical device according to claim 1, wherein the optical element is an isolator element including a Faraday rotator that rotates a plane of polarization of incident light. The optical device according to claim 1, wherein the optical element is an optical filter for multiplexing and / or demultiplexing incident light. A light emitting element, the optical device according to any one of claims 1 to 8, wherein light emitted from the light emitting element is incident on one optical fiber, and light is emitted from the other optical fiber, and the optical device And a light receiving element for receiving light emitted from the optical module.

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