JP2005265947A - Optical composite device, optical transmitting-receiving module, and manufacturing method of optical composite device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical composite device and an optical transmitting-receiving module which are small types and allows to correct a deviation of the optical axis. <P>SOLUTION: An optical isolator 6 and optical element substrates 7a, 7b located on both sides thereof are arranged in a groove 2a. The optical element substrate 7a has an optical filter 5 deposited on the surface in contact with a GI fiber 3b. The optical filter 5 is formed of a dielectric multi-layer which reflects a light beam of a predetermined wavelength and transmits a light beam of another wavelength. The optical filter 5, the optical isolator 6, and the optical element substrates 7 are formed in one body, and are embedded in the groove 2a in the integrated state. the light beam outgoing from the GI fiber 3b is reflected to the outside of a ferrule 2 by the optical filter 5. The light beam outgoing from a GI fiber 4b is made incident on the GI fiber 3b with the light path adjusted by the optical isolator 6 and the deviation of the optical axis reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical composite device used for optical communication and an optical transceiver module using the same. In particular, an optical composite device having a plurality of functions, in which an optical filter is supported by a material that transmits light, and an optical filter or mirror that multiplexes / demultiplexes light propagating in the optical fiber, and an optical isolator element are embedded. And an optical transceiver module including the optical composite device.

  As a subscriber communication system typified by FTTH (Fiber to the home), wavelength division multiplexing (WDM) in which bidirectional communication is performed using two wavelengths using an optical fiber, time division multiplexing (TDM: Time) (Division Multiplexing) is used.

  As a method of optically and efficiently connecting a light emitting element (or a light receiving element) and an optical fiber in a transmission module or a reception module used for optical fiber communication, conventionally, a lens is used and each position is adjusted with high accuracy. A method of fixing the optical element has been adopted. After that, by mounting optical fibers, light emitting elements (light receiving elements), etc. on a positioning bench using a highly accurate processed Si platform, etc., an optical communication device can be manufactured at low cost. And miniaturization is progressing.

  As a configuration for performing such optical fiber communication, an optical communication device described in Patent Document 1 is known. The optical transmission / reception module described in Patent Document 1 is mainly used in a subscriber network (access network), and an information transmission speed is several Mbps to several hundred Mbps. However, due to the trend toward higher speed and economy of optical networks, an inexpensive optical transmission / reception module having a transmission speed exceeding several Gbps has been required even in a subscriber network (access network).

  However, in the configuration of the optical transceiver module described in Patent Document 1, when communication is performed at a transmission speed exceeding several Gbps, the return light from the field is incident on the semiconductor laser as the light source through the optical fiber. May become unstable. As a result, it is difficult to increase the transmission speed. Therefore, it is conceivable to install an optical isolator used in high-speed communication in the optical transceiver module.

  When using an optical isolator, it is necessary to arrange in the optical axis of the light beam emitted from the semiconductor laser of the optical transceiver module. However, it is difficult for the optical transceiver module described in Patent Document 1 to dispose a general bulk optical isolator for optical communication. Therefore, it is necessary to embed an optical isolator in the optical path of the optical fiber in the same manner as the method of embedding the optical filter described in the document (Patent Document 1).

  Since the optical filter can form a dielectric multilayer film on a thin substrate such as polyimide or glass substrate, even if it is embedded in the optical path of the optical fiber, the loss of signal light passing through the optical fiber is relatively small. Note that the optical characteristics are controlled by the multilayer film portion (total film thickness is from a few μm to a few tens μm). However, since the thickness of the optical element that constitutes the optical isolator element is generally about 0.5 to 1.5 mm, the light emitted from the optical fiber is coupled to another corresponding optical fiber while the light is being coupled. Diffracts (spreads), so that there is a problem that the optical loss increases as the embedded element increases.

  Further, an optical isolator described in Patent Document 2 is known as an optical isolator element embedded in an optical path of an optical fiber. In this optical isolator, a core expansion optical fiber is used in which a portion of the optical fiber in which the optical isolator element is embedded is locally heated to expand the mode field diameter. The optical fiber is locally heated, and the dopant added to the core part for adjusting the refractive index is diffused into the cladding part, thereby producing a core-expanded optical fiber with an expanded mode field diameter.

  By using the core expansion optical fiber, even an optical element having a relatively large thickness can be embedded in the optical fiber with low loss. However, the loss may not be sufficiently reduced depending on the size (thickness) of the optical element embedded in the optical fiber. The light emitted from the core-enlarged optical fiber whose mode field diameter is enlarged follows the light diffraction principle, and the light spreading angle is reduced in inverse proportion to the spot size. Therefore, the optical connection loss is also reduced accordingly. However, the core expansion limit of an optical fiber that is generally used is about 40 μm. Further, in the core-expanded optical fiber, the optical in-phase surface (beam waist) is the end surface of the optical fiber as in the case of a general optical fiber. Therefore, the emitted light always spreads in the direction of divergence, and the loss always increases in proportion to the distance between the optical fibers.

  A configuration described in Patent Document 3 is known as an optical isolator element embedded in an optical path of an optical fiber. In this module, a refractive index distribution type optical fiber (graded index optical fiber: GI fiber) functioning as a lens is connected to the tip of a single mode optical fiber, and a coreless fiber for adjusting the focal length is further connected.

  With this configuration, the position of the beam waist can be changed by changing the structural parameter or the length of the gradient index optical fiber, so that the focal length becomes long. Accordingly, it is possible to embed a thick optical element between optical fibers with low loss.

Japanese Patent Laid-Open No. 2001-10062 JP-A-4-307512 JP 2002-14253 A

  In the case of a transmission module for transmission only, an optical isolator element embedded in an optical fiber is known. However, in the case of a transmission / reception module that performs bidirectional communication, it is necessary to provide means for optically connecting the transmission signal light to the light receiving element by a mirror or an optical filter that branches off from the optical axis. However, it is not preferable to separately form the optical filter insertion portion and the optical isolator element insertion portion in the optical path of the optical fiber because of high cost and large parts.

  When each element is mounted on a positioning bench, it is necessary to perform mechanical groove processing such as a dicing saw after mounting the optical fiber on the substrate. In that case, since the substrate is contaminated, additional cleaning is performed, and the bonding material, plating, and the like are deteriorated. Therefore, it is desirable that the components inserted into the optical fiber optical path can be passively mounted on a positioning substrate (such as a semiconductor bench) after being formed using a separate substrate.

  Therefore, an optical component for a transmission / reception module that includes an optical filter and an optical isolator element in an optical fiber and has a small size and high accuracy is required. Moreover, by integrating these elements, an optical component for a low-cost transmission / reception module is required.

  Accordingly, the present invention provides a small and low-cost optical composite device by forming a groove in an optical fiber support that supports an optical fiber, and inserting an optical filter or mirror and an optical isolator element into the groove. The purpose is to provide.

  However, when the light reflected by the optical filter or mirror is emitted to the outside from the optical fiber support and is formed with a groove having an angle surface that is incident on the external light receiving element, the light emitted from the optical fiber is otherwise There is a problem that a large optical axis misalignment occurs until the optical fiber is coupled to the other optical fiber, resulting in a large loss when coupled to another optical fiber.

  In addition, in a micro optical system using a gradient index optical fiber as a lens, the length of the gradient index optical fiber is processed with high accuracy in order to stably produce a predetermined spot size and a predetermined focal length. There is a need to. In general, since the cutting length accuracy of an optical fiber cutter used for an optical fiber fuser is about ± 0.5 mm, there is a problem that sufficient accuracy cannot be obtained and stable optical characteristics cannot be obtained. is there.

  The present invention solves the above problems, and a first object is to embed a composite optical element in which an optical element (an optical filter or mirror) and an optical isolator element are integrated between optical fibers, thereby providing a semiconductor laser. It is an object of the present invention to provide an optical composite device capable of stabilizing the high-speed operation and miniaturizing the optical transceiver module. It is another object of the present invention to provide an optical composite device capable of passive alignment mounting on a positioning bench (for example, Si bench) processed with high accuracy.

  A second object is to place an optical element having the largest difference in refractive index compared to the refractive index of the optical fiber at an angle different from the inclination angle of the groove, so that the optical fiber is emitted from the optical fiber to another optical fiber. Is to correct the optical axis shift of the light incident on. This is to reduce the coupling loss when coupled to another optical fiber.

  In addition, the third object is to use a light-transmitting substrate for the optical fiber support that supports the optical fiber, thereby increasing the length of the gradient index optical fiber that functions as a lens installed at the tip of the single mode optical fiber. And it is to adjust the distance to the groove with high accuracy.

  The invention according to claim 1 has light transmission properties, the first optical fiber arranged in a straight line, the second optical fiber arranged almost in the same straight line as the first optical fiber, and , Supporting the first optical fiber and the second optical fiber, and the light of the first optical fiber and the second optical fiber between the first optical fiber and the second optical fiber. An optical fiber support having a groove formed obliquely at a first angle with respect to the axis, and a composite optical element disposed in the groove, wherein the composite optical element is at least a Faraday An optical isolator element having a polarizer and a polarizer installed on both sides of the Faraday rotator, and an optical filter or mirror installed in at least one cross section of the groove, wherein the first angle is A first optical fiber or said first Of emitted from the optical fiber, the light reflected by the filter or the mirror is a light composite device, characterized in that the angle which is emitted to the outside of the optical fiber support.

  The optical filter has wavelength selectivity, reflects light having a predetermined wavelength, and transmits light having another wavelength. Further, the mirror does not have wavelength selectivity like an optical filter, and branches incident light according to the amount of light.

  For example, an optical filter is installed in the cross section of the groove on the first optical fiber side, and the optical filter reflects light having a predetermined wavelength emitted from the first optical fiber and emits it from the second optical fiber. It is assumed that light having a predetermined wavelength is transmitted. In this case, the light emitted from the first optical fiber is reflected by the optical filter and enters the optical fiber support. Based on the refractive index of the optical fiber support and the refractive index outside the optical composite device, the groove is formed in advance obliquely so that light is emitted from the optical fiber support to the outside of the optical composite device. When the groove is formed obliquely in this way, the light reflected by the optical filter is transmitted through the optical fiber support having optical transparency and emitted to the outside of the optical composite device.

  On the other hand, the light emitted from the second optical fiber passes through the optical isolator element, further passes through the optical filter, and enters the first optical fiber. Then, it propagates in the first optical fiber. The light transmitted through the optical isolator element is in a predetermined direction (one-way) and has a predetermined incident polarization plane. Therefore, the light transmitted through the isolator element and reflected by another optical element or the like again passes through the optical isolator element. It does not pass through and enter the second optical fiber. As a result, it is possible to prevent reflected return light to the second optical fiber.

  The invention according to claim 2 is the optical composite device according to claim 1, wherein the composite optical element is a wedge-shaped optical element between the optical isolator element and the optical filter or the mirror. The optical filter or the mirror, the wedge-shaped optical element, and the optical isolator element are integrally formed.

  Invention of Claim 3 is an optical composite device in any one of Claim 1 or Claim 2, Comprising: The said 1st optical fiber is a 1st single mode optical fiber at the front-end | tip at the 1st. A gradient index optical fiber is installed, and the second optical fiber has a second gradient index optical fiber installed at the tip of a second single-mode optical fiber, and the first optical fiber and the first optical fiber The second optical fiber is disposed so that the first gradient index optical fiber and the second gradient index optical fiber face each other, and the length of the first gradient index optical fiber is equal to the length of the first gradient index optical fiber. The second gradient index optical fiber has substantially the same length.

  A fourth aspect of the present invention is the optical composite device according to any one of the first to third aspects, wherein the first gradient index optical fiber and the second of the composite optical elements. The one having the largest difference from the refractive index on the central axis of the core of the gradient index optical fiber forms a second angle with respect to the optical axes of the first optical fiber and the second optical fiber. It is characterized by being installed diagonally.

  Since the groove is formed obliquely with respect to the optical axis, for example, the light emitted from the second optical fiber passes through the optical isolator element, and further passes through the optical filter and enters the first optical fiber. The optical axis shifts until it is done. Therefore, the optical path is corrected by obliquely arranging an element having the largest refractive index difference with respect to the optical fiber with respect to the optical axis shift caused when entering the obliquely formed groove. In other words, by disposing the element with the largest refractive index difference at a second angle different from the groove angle, the light is refracted in the direction opposite to the direction refracted when entering the groove, and the optical axis shifts. To cancel the optical axis and make it incident on the first optical fiber without any optical axis deviation. In this way, the coupling loss between optical fibers can be reduced by refracting light in the opposite direction with an element having the largest refractive index difference to cancel the optical axis deviation.

  A fifth aspect of the present invention is the optical composite device according to any one of the first to fourth aspects, wherein the first optical fiber and the second optical fiber are in the optical fiber support. It is inserted and supported.

  The invention according to claim 6 is the optical composite device according to any one of claims 1 to 4, wherein the optical fiber support has a linear groove formed on a surface thereof, The optical fiber and the second optical fiber are installed and supported in the linear groove.

  According to a seventh aspect of the present invention, there is provided a support substrate on which a linear positioning groove is formed, the optical composite device according to any one of the first to sixth aspects, wherein the optical composite device is installed in the positioning groove, and the second. A light-emitting element that causes light to enter the optical fiber, and a light-receiving element that receives the light emitted from the first optical fiber, reflected by the optical filter or the mirror, and transmitted through the optical fiber support. This is an optical transmission / reception module.

  The invention according to claim 8 is the optical transceiver module according to claim 7, wherein the second optical fiber is provided on the light emitting element side of the first optical fiber and the second optical fiber. A third optical fiber having a core diameter smaller than the core diameter is fusion-fixed.

  According to a ninth aspect of the present invention, there is provided an optical fiber support that supports an optical fiber, a groove that traverses the optical fiber and has a first angle with respect to the optical axis of the optical fiber is provided in the optical fiber. A groove forming step formed in the support, an optical isolator element having a Faraday rotator and a polarizer placed on both sides of the Faraday rotator, a wedge-shaped first optical element, and an optical filter on one surface Alternatively, a wedge-shaped second optical element provided with a mirror is prepared, the first optical element is bonded to one surface of the optical isolator element, and the first optical element is bonded The second optical element is bonded to the other surface of the optical isolator element by bonding the surface opposite to the surface on which the optical filter or the mirror is installed to the surface opposite to the surface, A first optical element and said A composite optical element having a configuration in which the optical isolator element is sandwiched between two optical elements, and the first optical element, the second optical element, and the optical isolator element are integrated. An optical composite device manufacturing method comprising: an element manufacturing step; and a step of embedding the integrated composite optical element in the groove formed in the optical fiber support.

  According to the optical composite device of the first aspect, since the groove formed in the optical fiber support is formed obliquely with respect to the optical axis of the optical fiber, the light reflected by the optical filter or the mirror The light can be emitted to the outside of the composite device and received by a light receiving element installed outside. In addition, by using a light-transmitting optical fiber support, the length of the optical fiber and the distance to the groove can be easily adjusted with high accuracy.

  According to the optical composite device of the second aspect, the optical isolator element and the optical filter or mirror are integrated and disposed between the optical fibers, whereby the entire element can be reduced in size. Manufacturing costs can be reduced.

  According to the optical composite device according to claim 4, among the optical elements constituting the composite optical element, the element having the largest refractive index difference compared to the optical fiber is disposed obliquely at the second angle. As a result, the groove portion is formed obliquely, and the optical axis deviation caused by refracting by individual substances having different refractive indexes in the groove can be canceled as a whole, and the optical axis deviation can be reduced. As a result, the coupling loss between the optical fibers can be reduced. Further, since the groove portion and the optical isolator element are formed obliquely with respect to the optical axis, it is possible to reduce the reflected return light reflected by them and returning to the optical fiber.

  According to the optical transceiver module according to claim 7, in addition to the effect obtained by the optical composite device, the optical composite device is arranged and fixed in a positioning groove formed in advance, thereby causing the light emitting element to emit light. This makes it possible to mount the optical composite device at the correct position without alignment. That is, since passive alignment can be performed, mounting of the optical composite device can be automated and simplified, and the number of assembly steps and cost can be reduced.

  According to the optical transceiver module of the eighth aspect, the third optical fiber having a smaller core diameter than the second optical fiber is fused and fixed to the light emitting element side, whereby the light emitted from the light emitting element and the second It is possible to improve the coupling with the optical fiber and reduce the coupling loss at that portion.

  According to the method for manufacturing an optical transceiver module according to claim 9, a compact optical transceiver module can be easily formed by embedding a composite optical element in which an optical filter or mirror and an optical isolator element are integrated between optical fibers. It can be produced. In addition, it is possible to reduce the manufacturing cost as compared with manufacturing an optical transmission / reception module by individually installing optical elements.

  Hereinafter, an optical composite device and an optical transceiver module according to embodiments of the present invention will be described with reference to FIGS.

  First, the configuration of an optical composite device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an optical composite device 1 according to an embodiment of the present invention. As shown in the figure, the optical composite device 1 according to this embodiment includes a ferrule 2 for fixing an optical fiber, optical fibers 3 and 4 with lenses, an optical filter 5, an optical isolator element 6, and an optical element substrate. 7 a and 7 b and a magnet 8.

  In the optical fibers 3 and 4 with lenses, GI fibers 3b and 4b as refractive index distribution type lenses are fixed to the ends of the single mode optical fibers 3a and 4a by fusion.

The GI fibers 3b and 4b are refractive index distribution type optical fibers having a refractive index distribution in the radial direction of the optical axis, and the refractive index distribution in the radial direction of the GI fiber is expressed by the following equation (1). Is done.
n (r) = n0 (1- (A / 2) r ² ) (1)
Here, r is a radial radius from the central axis, and n0 is a refractive index on the central axis of the core. A ^1/2 is a refractive index distribution constant. When the refractive index is a square distribution, A ^1/2 = (2Δ) ^1/2 / r. Here, Δ is a relative refractive index difference.

  This GI fiber has a function of converting a divergent light beam emitted from a single mode optical fiber into a parallel light beam or a convergent light beam, or converting a light beam incident on the optical fiber into a convergent light beam.

The ferrule 2 is made of a glass ferrule that is made of borosilicate glass or quartz glass and transmits light. The ferrule 2 has an insertion hole into which the optical fibers 3 and 4 with lenses are inserted. Furthermore, the ferrule 2, (1, the angle from the direction perpendicular to the optical axis and theta _g) a predetermined angle to the optical axis of the lensed optical fiber 3 held in the ferrule 2 so as to form a A groove 2a is formed in the groove. The ferrule 2 corresponds to the “optical fiber support” of the present invention.

  The optical fiber with lens 3 and the optical fiber with lens 4 are inserted into the insertion hole of the ferrule 2 with the groove 2a therebetween so that the GI fiber 3b and the GI fiber 4b face each other. Furthermore, the end faces of the GI fibers 3b and 4b are inclined at the same angle as the groove 2a with respect to the optical axis.

  An optical isolator element 6 is installed in the groove 2a. The optical isolator element 6 includes a Faraday rotator 6a having a rotation angle of 45 degrees and polarizers 6b and 6c that are provided on both sides of the Faraday rotator 6a and whose polarization directions are inclined by 45 degrees. A magnet 8 that magnetizes the Faraday rotator 6a of the optical isolator element 6 in a certain direction is provided around the Faraday rotator 6a.

  Furthermore, wedge-shaped optical element substrates 7 a and 7 b are installed on both sides of the optical isolator element 6. Specifically, a wedge-shaped optical element substrate 7a made of glass is placed between the optical isolator element 6 and the GI fiber 3b, and a wedge-shaped shape made of glass is placed between the optical isolator element 6 and the GI fiber 4b. The optical element substrate 7b is installed. The optical element substrates 7a and 7b correspond to the “wedge-shaped optical element” of the present invention.

  The optical element substrate 7a has an optical filter 5 formed on the surface in contact with the GI fiber 3b. Therefore, the optical filter 5 is provided between the optical element substrate 7a and the GI fiber 3b. The optical filter 5 has a wavelength selectivity, and a dielectric multilayer film that reflects light having a predetermined wavelength and transmits a light beam having another wavelength is used. Further, instead of the optical filter, a mirror that branches light may be used. In this case, light is not demultiplexed by wavelength selection like an optical filter, but light is branched according to the amount of light.

  As described above, the optical filter 5, the optical isolator element 6, and the optical element substrate 7 are integrally formed, and are embedded in the groove 2a in the integrated state. The optical filter 5, the optical isolator element 6, and the optical element substrate 7 that are integrally formed correspond to the “composite optical element” of the present invention.

Further, in the optical element substrate 7a, the surface opposite to the surface on which the optical filter 5 is formed has a predetermined angle with respect to the optical axis of the optical fibers 3 and 4 with lenses (in FIG. 1, orthogonal to the central axis) form a illustrated as angle theta _f from the axis) to, are inclined at an angle different from the angle of the groove 2a. The optical element substrate 7b is inclined at an angle different from the angle of the groove 2a, with the opposite surface facing the GI optical fiber 4b forming a predetermined angle θ _f with respect to the optical axis of the optical fibers 3 and 4 with lenses. doing.

Further, the polarizer 6b, the surface in contact with the Faraday rotator 6a is inclined at an angle different from the angle of the groove 2a at an angle theta _f. Polarizer 6c, the surface in contact with the Faraday rotator 6a is inclined at an angle different from the angle of the groove 2a at an angle theta _f. Thus, the Faraday rotator 6a is both sides of the surface in contact with a polarizer 6b and the polarizer 6c are inclined at an angle theta _f. That is, the whole optical isolator element 6 is inclined at an angle theta _f. In this embodiment, the optical isolator element 6 is inclined obliquely by sandwiching the optical isolator element 6 between the wedge-shaped optical element substrates 7a and 7b.

In the present embodiment, among the optical elements constituting the composite optical element, the Faraday rotator 6a has the largest refractive index, and the element having the largest difference from the refractive index on the central axis of the core of the GI fiber. . Then, the large Faraday rotator 6a refractive index is best (refractive index = 2.41) was placed obliquely at an angle theta _f.

Although the whole optical isolator element 6 inclined angle theta _f, it may be inclined only Faraday rotator 6a constituting the optical isolator element 6. In this case, it is also possible to insert a wedge-shaped glass between the polarizer 6b (6c) and the Faraday rotator 6a, and adjust the angle of the wedge-shaped glass to tilt only the Faraday rotator 6a.

  Further, a substrate 9 serving as a reference surface indicating the incident polarization direction of the optical isolator element 6 is installed on the side surface of the ferrule 2. The substrate 9 has a function of improving the mechanical strength of the groove formed in the ferrule 2 in addition to the function as a reference surface. Furthermore, a glass substrate can be used as the material of the substrate 9, and the cut filter 9a can be formed on the surface. The cut filter 9 a has a function of removing an extra signal from the light reflected by the optical filter 5. Moreover, you may use the glass substrate in which AR coating was formed into a film instead of the cut filter 9a. Note that the substrate 9 having these effects may not be installed.

  Such an optical composite device is formed by cutting the ferrule 2 with an outer peripheral slicer such as a dicing saw to form the groove 2a, and embedding a composite optical element in which the optical filter 5, the optical isolator element 6, and the optical element substrate 7 are integrated, It is produced by bonding and fixing. Thereby, since the optical fibers 3 and 4 with a lens are arranged on a straight line, the optical axis alignment between optical fibers becomes unnecessary, and it becomes possible to produce the optical composite device 1 easily.

  A method for manufacturing the optical composite device 1 will be described in more detail. First, the optical filter 5 is formed on one surface of a substrate made of glass. Then, the surface opposite to the surface on which the optical filter 5 is formed is cut obliquely to produce a wedge-shaped optical element substrate 7a. The optical element substrate 7b is also formed in a wedge shape by cutting the surface obliquely. Note that the optical filter 5 may be formed on one surface of the optical element substrate 7a that has been wedge-shaped by cutting the surface in advance.

  Next, the optical isolator element 6 is sandwiched and bonded by the wedge-shaped optical element substrates 7a and 7b to form a composite optical element in which the optical filter, the optical element substrates 7a and 7b, and the optical isolator element 6 are integrated. . As for the optical element substrate 7a, the surface opposite to the surface on which the optical filter 5 is formed is in contact with and bonded to the optical isolator element 6. The optical filter 5 may be formed on the optical element substrate 7a after the optical isolator element 6 is sandwiched and bonded by the wedge-shaped optical element substrates 7a and 7b.

  Then, the composite optical device 1 is fabricated by embedding the integrated composite optical element in the groove 2a of the ferrule 2 and bonding and fixing it. Thus, by integrating the optical elements having different functions (the optical filter 5, the optical element substrates 7a and 7b, and the optical isolator element 6), it becomes possible to reduce the size of the composite optical device 1, and optically separately. Manufacturing costs can be reduced as compared to installing elements.

  Moreover, in this embodiment, since the ferrule 2 consists of borosilicate glass or quartz glass, and has optical transparency, it becomes possible to install the optical fibers 3 and 4 with a lens with high precision.

  The optical fibers 3 and 4 with a lens are not manufactured separately, but are manufactured using a single-mode optical fiber fused and fixed in advance to both ends of a GI fiber. An optical fiber composed of a single mode optical fiber-GI fiber-single mode optical fiber is prepared in advance, and is inserted into the insertion hole of the ferrule 2 having optical transparency and bonded and fixed. After bonding, the ferrule 2 is scraped to form the groove 2a in consideration of the joining position of the single mode optical fiber and the GI fiber and the length of the GI fiber. When the groove 2a is formed, the GI fiber is also shaved together, thereby adjusting the length of the GI fiber. Such an operation is possible because the ferrule 2 has light transmittance.

  As described above, since the length of the GI fiber and the distance to the groove can be easily adjusted with high accuracy, a high-performance optical composite device can be easily manufactured.

  In the present embodiment, the example using the ferrule 2 in which the optical fibers 3 and 4 with lenses are inserted has been described. However, the present invention is not limited to this, and any optical fiber support having optical transparency may be used. . For example, the optical fibers 3 and 4 with a lens may be supported by a glass substrate on which a linear groove that supports the optical fibers 3 and 4 with a lens is formed. The cross-sectional shape of the groove may be formed in a V-shape, and the optical fibers 3 and 4 with lenses may be placed in the V-shaped groove, and the optical composite device may be manufactured by pressing and bonding with a glass substrate from above. Since at least one of the substrate having the groove or the substrate pressed from above may be a transmissive substrate, a free-cutting substrate such as ferrite can be used instead of the glass substrate. Note that the cross-sectional shape of the groove does not have to be V-shaped but may be rectangular.

  Next, the configuration of the optical transmission / reception module including the optical composite device according to the present embodiment will be described with reference to FIGS. FIG. 2 is a top view of the optical transceiver module according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of the optical transceiver module according to the embodiment of the present invention.

  As shown in FIG. 2, the optical transceiver module 10 according to the present embodiment mainly includes a support substrate 11 and an optical composite device 1 mounted on the support substrate 11. The support substrate 11 may be, for example, a semiconductor substrate such as Si, GaAs, or InP, a precisely processed glass substrate, a ceramic substrate, or a metal substrate. The support substrate 11 is formed with a V-groove 16 and a V-groove 17 narrower than the V-groove 16 on the same axis.

  The ferrule 2 of the optical composite device 1 is pushed into the V groove 16 and fixed. Further, the single mode optical fiber 4a is pushed into the V groove 17 and fixed. A light emitting element 12 made of, for example, a semiconductor laser and outputting a light signal to the single mode optical fiber 4a and a monitor element 13 for monitoring the light emitting element 12 are provided at the tip of the single mode optical fiber 4a.

  Further, as shown in FIG. 3, a groove 18 is formed in the V groove 16 at a position corresponding to the optical element 5. In the groove 18, a light receiving element 14 to which an optical signal from the optical fiber 3 a is input and A preamplifier 15 is installed. When the substrate 9 on which the cut filter 9 a is formed is installed in the optical composite device 1, the substrate 9 is inserted into the groove 18.

  Generally, a semiconductor substrate such as Si is used as the support substrate 11 and the V-grooves 16 and 17 are formed by a photolithography technique, so that the optical composite device 1 and the light emitting element 12 can be accurately aligned. It becomes. That is, since the alignment pattern of the V-grooves 16 and 17 and the light emitting element 12 can be formed with high precision by high-precision photolithography technology, the optical composite device 1 is accurately positioned with the V-grooves 16 and 17. The issuing element 12 can be mounted in the correct position by the alignment pattern. As a result, the light emitting element 12 can be accurately arranged on the axis of the optical composite device 1, and the optical composite device 1 can be mounted at a correct position without causing the light emitting element 12 to emit light and aligning. Thus, since passive alignment can be performed, the mounting of the optical composite device 1 can be automated, and the number of assembly steps can be reduced and the cost can be reduced.

  In the present embodiment, the optical composite device 1, the light emitting element 12, and the light receiving element 14 are installed on the support substrate 11 made of a semiconductor such as Si. It may be provided. Even in that case, the same operations and effects as the present embodiment can be achieved.

(Action and effect)
According to the optical composite device 1 and the optical transceiver module 10 including the same according to the present embodiment, the following preferable functions and effects can be achieved.

  The light having a predetermined wavelength propagating through the single mode optical fiber 3 a is emitted from the tip of the GI fiber 3 b and reflected by the optical filter 5. Thus, the characteristics of the optical filter 5 are determined in advance so as to reflect the light having a predetermined wavelength emitted from the optical fiber 3 with a lens.

Groove 2a is (1, the angle from the direction perpendicular to the optical axis and theta _g) a predetermined angle to the optical axis of the lensed optical fiber 3 and 4 because of the inclined at a light Is reflected by the optical filter 5 at a predetermined angle with respect to the optical axis of the optical fiber 3 with a lens. Since the ferrule 2 is made of transparent glass, the light reflected by the optical element 5 passes through the ferrule 2 and enters the light receiving element 14. Thus, since the groove 2a is inclined with respect to the optical axis, the reflected return light returning to the optical fiber 3 with a lens out of the light reflected by the optical filter 5 can be reduced. At the same time, the reflected light can be incident on the light receiving element 14 installed outside the optical composite device 1.

  When the cut filter 9a is provided on the side surface of the ferrule 2, the light transmitted through the ferrule 2 further passes through the cut filter 9a. By providing this cut filter 9a, it becomes possible to reduce the influence of optical coupling loss, light scattering, or optical crosstalk. Further, by providing a glass substrate with an AR coat instead of the cut filter 9a, reflection loss and light scattering can be suppressed.

  On the other hand, the light emitted from the light emitting element 12 enters the single mode optical fiber 4a, propagates through the single mode optical fiber 4a, exits from the GI fiber 4b, and enters the optical element substrate 7b. At this time, since the groove 2a is inclined with respect to the optical axis, the reflected return light returning to the optical fiber with lens 4 out of the light reflected by the end face of the GI fiber 4b can be reduced.

  The light incident on the optical element substrate 7 b passes through the optical element substrate 7 b and enters the polarizer 6 c of the optical isolator element 6. The light incident on the polarizer 6c is linearly polarized light having an axis in a predetermined direction and substantially coincides with the incident polarization direction of the polarizer 6c. Therefore, the light passes with low loss, and the Faraday rotator 6a. Is incident on. Since the rotation angle of the Faraday rotator 6a is 45 degrees, when the light passes through the Faraday rotator 6a, it becomes linearly polarized light whose axis is inclined by 45 degrees. And it injects into the polarizer 6b whose polarization direction inclined 45 degree | times with respect to the polarizer 6c. Since the linearly polarized light is inclined 45 degrees by the Faraday rotator 6a, the light passes through the polarizer 6b.

  The light transmitted through the optical isolator element 6 further passes through the optical element substrate 7 a and the optical filter 5 and enters the GI fiber 3 b in the ferrule 2. As described above, the characteristics of the optical filter 5 are determined in advance so as to transmit light having a predetermined wavelength emitted from the optical fiber 4 with a lens. The light incident on the GI fiber 3b enters the single mode optical fiber 3a and propagates through the single mode optical fiber 3a. When light enters the GI fiber 3b, it may be reflected by elements such as the optical filter 5 and the optical element substrate 7a, and the reflected light may enter the polarizer 6b. The linearly polarized reflected light incident on and transmitted through the polarizer 6b is further tilted by 45 degrees when transmitted through the Faraday rotator 6a. Therefore, the polarization direction is rotated 90 degrees by passing through the Faraday rotator 6a twice. As a result, the reflected light cannot pass through the polarizer 6c, and the reflected light does not return to the optical fiber 4 with a lens.

A part of the light emitted from the optical fiber 4 with a lens is reflected by the end face of the polarizer 6c, but the optical isolator element 6 is at a predetermined angle with respect to the optical axis (in FIG. 1, orthogonal to the optical axis). due to the inclined at an angle from the direction and theta _f), it is possible to reduce the reflected return light returning to the lensed optical fiber 4.

  As described above, since the groove 2a and the optical isolator element 6 each have a predetermined angle with respect to the optical axis, it is possible to reduce the reflected return light returning to the optical fibers 3 and 4 with a lens. And it becomes possible to reduce reflected return light further, so that an inclination angle is enlarged.

  However, since the groove 2a is inclined obliquely at a predetermined angle, a large optical axis shift occurs until the light emitted from the optical fiber 4 with a lens enters the optical fiber 3 with a lens, Loss when coupled to the optical fiber 3 with a lens is increased. At this time, the optical axis deviation can be corrected by adjusting the angle of the compound optical element having the largest refractive index.

  In the present embodiment, the refractive index of the Faraday rotator 6a is the largest, and the relative refractive index difference between the optical fibers 3 and 4 with a lens is the largest. By tilting the Faraday rotator 6a at a predetermined angle, the optical axis deviation can be corrected. That is, by disposing the element having the largest refractive index difference (in this embodiment, the Faraday rotator 6a) obliquely, the light is refracted in the direction opposite to the direction refracted when entering the groove 2a. The axial deviation is canceled out, and the light is incident on the optical fiber 3 with a lens without any optical axis deviation. In this way, the coupling loss between the optical fibers can be reduced by refracting light in the opposite direction with an element having the highest refractive index to cancel the optical axis deviation.

(Example)
Next, the angle at which light is emitted to the outside of the optical composite device 1 will be specifically described with reference to FIGS. 4 to 8. FIG. 4 is a cross-sectional view of the optical composite device according to the first and second embodiments. FIG. 5 is a cross-sectional view of the optical composite device according to the third and fourth embodiments. FIG. 6 is a cross-sectional view of the optical composite device in Example 5 and Example 6. 7 and 8 are tables summarizing Examples 1 to 6. FIG.

(Example 1)
In Example 1, the configuration of the optical composite device 1 was specifically as follows.
Refractive index of ferrule 2 (borosilicate glass): 1.49
External space of the optical composite device 1: air (refractive index = 1.00)
Angle θ _{g of} groove 2a: 45 °

Under the above conditions, the light emitted from the optical fiber 3 with a lens is reflected by an optical filter 5 at a reflection angle θ _r = 90 ° (angle formed with the optical axis of the optical fiber 3 with a lens) as shown in FIG. Reflected. The light then passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (air) perpendicularly. In other words, when the direction perpendicular to the boundary surface is taken as the reference axis, the light enters the angle θ ₁ = 0 ° with respect to the reference axis. And it radiate | emits perpendicular | vertical to external space (air). That is, the light is emitted at an angle θ ₂ = 0 ° with respect to the reference axis. The light emitted from the ferrule 2 is received by the external light receiving element 14.

(Example 2)
Refractive index of ferrule 2 (quartz glass): 1.44
External space of the optical composite device 1: resin (refractive index = 1.52)
Angle θ _{g of} groove 2a: 45 °

Under the above conditions, the light emitted from the optical fiber 3 is reflected by the optical filter 5 at a reflection angle θ _r = 90 ° as shown in FIG. The light then passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (resin) perpendicularly. In other words, when the direction perpendicular to the boundary surface is taken as the reference axis, the light enters the angle θ ₁ = 0 ° with respect to the reference axis. And it radiate | emits perpendicular | vertical to external space (air). That is, the light is emitted at an angle θ ₂ = 0 ° with respect to the reference axis. The light emitted from the ferrule 2 is received by the light receiving element 14.

  As can be seen from the first and second embodiments, when the angle of the groove 2a is 45 ° and light is vertically incident on the boundary surface between the ferrule 2 and the external space, the light is perpendicular to the external space from the ferrule 2. Will be emitted.

(Example 3)
In Example 3, the configuration of the optical composite device 1 was specifically set as follows.
Refractive index of ferrule 2 (borosilicate glass): 1.49
External space of the optical composite device 1: air (refractive index = 1.00)
Angle θ _{g of} groove 2a: 30 °

Under the above conditions, the light emitted from the optical fiber 3 is reflected by the optical filter 5 at a reflection angle θ _r = 60 ° as shown in FIG. Then, the light passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (air) at an incident angle θ ₁ = 30 °. And it radiate | emits by the output angle (theta) ₂ = about 48.2 degrees to external space (air). The light emitted from the ferrule 2 is received by the light receiving element 14.

Example 4
In Example 4, the configuration of the optical composite device 1 was specifically set as follows.
Refractive index of ferrule 2 (quartz glass): 1.44
External space of the optical composite device 1: resin (refractive index = 1.52)
Angle θ _{g of} groove 2a: 30 °

Under the above conditions, the light emitted from the optical fiber 3 is reflected by the optical filter 5 at a reflection angle θ _r = 60 ° as shown in FIG. Then, the light passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (resin) at an incident angle θ ₁ = 30 °. Then, the light is emitted to the external space (resin) at an emission angle θ ₂ = about 28.3 °. The light emitted from the ferrule 2 is received by the light receiving element 14.

(Example 5)
In Example 5, the configuration of the optical composite device 1 was specifically set as follows.
Refractive index of ferrule 2 (borosilicate glass): 1.49
External space of the optical composite device 1: air (refractive index = 1.00)
Angle θ _{g of} groove 2a: 15 °

Under the above conditions, the light emitted from the optical fiber 3 is reflected at the reflection angle θ _r = 30 ° by the optical filter 5 as shown in FIG. Then, the light passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (air) at an incident angle θ ₁ = 60 °. The light incident on the boundary surface is totally reflected on the boundary surface without being emitted to the external space (air), and propagates through the ferrule 2. Under the conditions of the fifth embodiment, the light emitted from the optical fiber 3 is not emitted outside the optical composite device 1 and is not received by the light receiving element 14.

(Example 6)
In Example 6, the configuration of the optical composite device 1 was specifically as follows.
Refractive index of ferrule 2 (quartz glass): 1.44
External space of the optical composite device 1: resin (refractive index = 1.52)
Angle θ _{g of} groove 2a: 15 °

Under the above conditions, the light emitted from the optical fiber 3 is reflected by the optical filter 5 at a reflection angle θ _r = 30 °. Then, the light passes through the ferrule 2 and enters the boundary surface between the ferrule 2 and the external space (resin) at an incident angle θ ₁ = 60 °. Then, the light is emitted to the external space (resin) at an emission angle θ ₂ = about 55.1 °. The light emitted from the ferrule 2 is received by the light receiving element 14.

  Each example has been specifically described above, but a summary of each example is shown in the tables of FIGS. FIG. 7 shows that when the ferrule 2 is made of borosilicate glass (refractive index = 1.49) and the external space of the optical composite device 1 is made of air (refractive index = 1.0), the light is emitted from the ferrule 2 to the external space. It is a table | surface which shows the emission angle of the light to be performed.

As can be seen from the table of FIG. 7, under the condition “refractive index of ferrule 2> refractive index of external space”, the incident angle θ ₁ to the boundary surface is critical angle θ _c : sin θ _c = (refractive index of external space / Refractive index of ferrule 2), light does not exit to the external space due to total reflection. In this embodiment, the critical angle θ _c = about 42.2 °.

  FIG. 8 shows the case where the ferrule 2 is made of quartz glass (refractive index = 1.44) and the external space of the optical composite device 1 is made of resin (refractive index = 1.52). It is a table | surface which shows the outgoing angle of the light radiate | emitted.

  As can be seen from the table of FIG. 8, under the condition “refractive index of ferrule 2 <refractive index of external space”, if the light reflected by the optical filter 5 installed in the groove 2a can reach the boundary surface, Light can be emitted to the external space.

As described above, in order to emit light from the optical fiber with lens 3 to the outside of the optical composite device 1, the inclination angle θ of the groove 2a is determined by the refractive index of the ferrule 2 and the refractive index of the optical composite device 1. _It is necessary to change _g to an appropriate angle. As described above, the “angle that is emitted to the outside of the optical fiber support” in the present invention is an appropriate angle corresponding to the refractive index of the ferrule 2 and the external refractive index.

(Example 7)
Next, an embodiment for adjusting the optical axis deviation will be described with reference to FIG. FIG. 9 is a graph showing the optical axis deviation when light is incident on the optical fiber 3 with a lens with respect to the angle θ _f of the optical isolator element 6 (Faraday rotator 6a).

In this example, the configuration of the optical composite device 1 was specifically as follows.
Single mode optical fiber 3a, 4a: A quartz single mode optical fiber having a clad diameter of 125 [μm] and a mode field diameter of about 9.5 [μm] was used.
GI fibers 3b and 4b: On-axis refractive index n0 = 1.446, relative refractive index difference = 0.85%
Optical filter 5: An optical filter made of a dielectric multilayer film having a thickness = 10 [μm] and an effective refractive index n1 = 1.61 was used. This optical filter transmits light having a wavelength of 1300 to 1500 nm and reflects light having a wavelength of 1540 to 1620 nm.
Optical element substrates 7a and 7b: made of a glass substrate having a thickness = 500 [μm] and a refractive index n4 = 1.51.
Faraday rotator 6a: thickness = 360 [μm], refractive index n2 = 2.41
Polarizers 6b and 6c: thickness = 200 [μm], refractive index n3 = 1.51

In addition, a semiconductor laser having an output wavelength of 1310 [nm] is used as the light emitting element 12, and light having a wavelength of 1550 [nm] propagates through the single mode optical fiber 3a. Moreover, the approximately 45 ° angle theta _g of the groove 2a.

Then, the optical axis shift of the light beam incident on the single mode optical fiber 3a was examined by changing the angle θ of the optical isolator element 6. FIG. 9 shows the result. In the figure, the horizontal axis indicates the angle θ _f [degree] of the optical isolator element 6 (Faraday rotator 6a), and the vertical axis indicates the optical axis deviation [μm].

As shown in the figure, when the angle θ _f of the optical isolator element 6 (Faraday rotator 6a) is about 28 degrees, the optical axis deviation is almost 0 [μm]. In other words, by tilting the optical isolator element 6 (Faraday rotator 6a) in a direction opposite to the tilt direction of the groove 2a, the optical axis shift caused by refraction by a material having a different refractive index is canceled as a whole, and the optical axis The deviation can be reduced.

  By eliminating the optical axis deviation in this way, it is possible to reduce the coupling loss that occurs when the light emitted from the optical fiber 4 with a lens enters the optical fiber 3 with a lens.

  In the present embodiment, the polarizers 6b and 6c are also inclined in the same manner as the Faraday rotator 6a, but the difference in refractive index between the optical element substrates 7a and 7b and the polarizers 6b and 6c is small. Even if the polarizers 6b and 6c are inclined, there is almost no effect of correcting the optical axis deviation. That is, since the refractive index difference is small, the polarizers 6b and 6c are hardly refracted, and the optical axis deviation cannot be offset. Therefore, the effect of correcting the optical axis deviation is mainly obtained by the Faraday rotator 6a, and the same effect can be obtained by tilting only the Faraday rotator 6a.

  Further, since the groove 2a is inclined at an angle of about 45 degrees, the light having a wavelength of 1550 [nm] propagating through the single mode optical fiber 3a is about 90 with respect to the optical axis by the optical element 5. It will be reflected in the direction of degrees. In other words, since the light can be reflected in a direction orthogonal to the optical composite device 1, the light can be efficiently incident on the light receiving element 14.

  Further, in order to improve the coupling between the light emitted from the light emitting element 12 and the optical fiber, the tip of the single mode optical fiber 4a has a high relative refractive index difference and a small core diameter (single mode conditions are satisfied. ) It is better to fuse and fix the optical fiber. It should be noted that the fused portion between the single mode optical fiber 4a and an optical fiber (HiΔ optical fiber) having a high relative refractive index difference and a small core diameter has a large difference in core diameter, resulting in loss. However, the core diameter of the HiΔ optical fiber can be expanded stepwise in a predetermined region by heat-treating the fused portion. By this process, it is possible to reduce the loss at the fused portion.

  For example, when the spot size of the light emitted from the light emitting element 12 is about 1.0 [μm], when the light is directly received by the single mode optical fiber 4a having the mode field diameter of about 9.5 [μm], the core diameter is large. Therefore, a loss occurs in the coupling. A composite optical fiber capable of reducing the coupling loss will be described with reference to FIG. FIG. 10 is a cross-sectional view of a composite optical fiber according to another embodiment.

  As shown in the figure, the composite optical fiber according to this embodiment is a heat-treated TEC light installed between the optical fiber 4c having a high relative refractive index difference and a small core diameter and the single mode optical fiber 4a. It consists of a fiber 4d, a single mode optical fiber 4a, and a GI fiber 4b fixed to the tip thereof by fusion.

Here, the configuration of each optical fiber will be described.
Single mode optical fiber 4a: Core diameter is about 9.5 [μm], relative refractive index difference is 0.3%
Optical fiber 4c: Core diameter is about 4 [μm], relative refractive index difference is 1.2%
TEC optical fiber 4d: The core diameter gradually increases from the side facing the optical fiber 4c toward the single mode optical fiber 4a. Specifically, the core diameter of the portion facing the optical fiber 4c is about 4 [μm], the core diameter gradually increases toward the single mode optical fiber 4a, and the core facing the single mode optical fiber 4a. The diameter is about 9.5 [μm].

  The TEC optical fiber 4d having a gradually changing core diameter is manufactured by applying heat from the periphery, diffusing a dopant such as Ge contained in the core into the cladding, and changing the refractive index.

  Thus, by receiving the light emitted from the light emitting element 12 with the optical fiber 4c having a small core diameter, the coupling loss can be reduced as compared with the case of directly receiving the light with the single mode optical fiber 4a having the large core diameter. it can. Then, by sandwiching the TEC optical fiber 4d between the optical fiber 4c and the single mode optical fiber 4a, the core diameter is gradually increased from the optical fiber 4c having a small core diameter, and the single mode optical fiber having a large core diameter is obtained. 4a can be combined.

It is sectional drawing of the optical composite device which concerns on embodiment of this invention. It is a top view of the optical transmission / reception module which concerns on embodiment of this invention. It is sectional drawing of the optical transmission / reception module which concerns on embodiment of this invention. It is sectional drawing of the optical composite device which shows one Example of this invention. It is sectional drawing of the optical composite device which shows one Example of this invention. It is sectional drawing of the optical composite device which shows one Example of this invention. It is the table | surface which put together the Example of this invention. It is the table | surface which put together the Example of this invention. It is a graph showing the optical axis offset of light with respect to the angle change of the optical isolator which concerns on embodiment of this invention. It is sectional drawing of the optical fiber which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical composite device 2 Ferrule 3, 4 Optical fiber with lens 5 Optical filter 6a Faraday rotator 6b, 6c Polarizer 7a, 7b Optical element board | substrate 8 Magnet 9 Board | substrate 9a Cut filter 10 Optical transmission / reception module 11 Mounting board 12 Light emitting element 13 Monitor light receiving element 14 Light receiving element 15 Preamplifier 16, 17 V groove 18 groove

Claims (9)

A first optical fiber arranged in a straight line;
A second optical fiber disposed substantially collinearly with the first optical fiber;
It has optical transparency, supports the first optical fiber and the second optical fiber, and the first optical fiber and the second optical fiber between the first optical fiber and the second optical fiber. An optical fiber support having a groove formed obliquely at a first angle with respect to the optical axis of the two optical fibers;
A composite optical element installed in the groove,
The composite optical element has at least an optical isolator element having a Faraday rotator and a polarizer installed on both sides of the Faraday rotator, and an optical filter or mirror installed on at least one cross section of the groove. ,
The first angle is an angle at which light emitted from the first optical fiber or the second optical fiber and reflected by the filter or the mirror is emitted to the outside of the optical fiber support. An optical composite device characterized by that. The composite optical element has a wedge-shaped optical element between the optical isolator element and the optical filter or the mirror,
The optical composite device according to claim 1, wherein the optical filter or the mirror, the wedge-shaped optical element, and the optical isolator element are integrally formed. The first optical fiber has a first gradient index optical fiber installed at the tip of the first single mode optical fiber,
The second optical fiber is provided with a second gradient index optical fiber at the tip of the second single mode optical fiber,
The first optical fiber and the second optical fiber are arranged such that the first gradient index optical fiber and the second gradient index optical fiber face each other,
3. The light according to claim 1, wherein a length of the first gradient index optical fiber and a length of the second gradient index optical fiber are substantially the same. 4. Composite device. Among the composite optical elements, the one having the largest difference between the refractive index on the central axis of the core of the first gradient index optical fiber and the second gradient index optical fiber is the first optical element. 4. The optical composite device according to claim 1, wherein the optical composite device is disposed obliquely at a second angle with respect to the optical axes of the optical fiber and the second optical fiber. 5. 5. The optical composite device according to claim 1, wherein the first optical fiber and the second optical fiber are inserted into and supported by the optical fiber support body. The optical fiber support has a linear groove formed on a surface thereof, and the first optical fiber and the second optical fiber are installed and supported in the linear groove. The optical composite device according to claim 1. A support substrate on which linear positioning grooves are formed;
The optical composite device according to any one of claims 1 to 6 installed in the positioning groove,
A light emitting element for making light incident on the second optical fiber;
A light receiving element that receives light emitted from the first optical fiber, reflected by the optical filter or the mirror, and transmitted through the optical fiber support;
An optical transceiver module comprising: In the second optical fiber, a third optical fiber having a core diameter smaller than the core diameter of the first optical fiber and the second optical fiber is fused and fixed to the light emitting element side. 8. The optical transceiver module according to claim 7, Prepare an optical fiber support that supports the optical fiber,
Forming a groove in the optical fiber support that traverses the optical fiber and has a first angle with respect to the optical axis of the optical fiber;
An optical isolator element having a Faraday rotator and polarizers disposed on both sides of the Faraday rotator, a wedge-shaped first optical element, and a wedge-shaped shape in which an optical filter or mirror is installed on one surface A second optical element;
Bonding the first optical element to one surface of the optical isolator element;
The surface opposite to the surface on which the optical filter or the mirror is installed is bonded to the surface opposite to the surface to which the first optical element is bonded, so that the surface on the other side of the optical isolator element Glue the second optical element,
The optical isolator element is sandwiched between the first optical element and the second optical element, and the first optical element, the second optical element, and the optical isolator element are integrated. A composite optical element manufacturing process for manufacturing the composite optical element;
Embedding the integrated composite optical element in the groove formed in the optical fiber support;
A method for manufacturing an optical composite device, comprising:

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