JP2008209520A - Optical filter module - Google Patents

Abstract

An optical filter module that is small in size and easy to align is provided.
A plurality of substrates each having a reflecting surface that reflects light of a corresponding wavelength includes a filter substrate that is laminated so that the reflecting surfaces are parallel to each other, and includes a first optical fiber and a plurality of second optical fibers. One end portion of the first optical fiber is optically connected to the filter substrate on the same side with respect to each reflection surface, and the first optical fiber has an axial direction of an angle α with respect to a direction perpendicular to each reflection surface. The plurality of second optical fibers are on the same plane as the first optical fiber, on the opposite side to the first optical fiber with respect to the direction perpendicular to each reflecting surface, and the axial direction thereof is in the direction perpendicular to the reflecting surface. In contrast, they are arranged so as to have an angle α.
[Selection] Figure 1

Description

  The present invention relates to an optical filter module for use in, for example, an optical multiplex transmission type optical communication device and an optical sensing system device using a plurality of optical wavelengths.

Various optical communication components are used for downsizing and integration of optical circuits in optical communication devices. One example is the multi-core optical multiplexer / demultiplexer shown in FIG. In this optical multiplexer / demultiplexer, two (103a, 103b) are prepared in which an optical fiber with a tip lens is mounted on an optical fiber alignment substrate. Here, the optical fiber with a tip lens is a refractive index distribution type (graded index type, hereinafter referred to as “GI”) multimode fiber at one end of a single mode fiber (hereinafter, referred to as “SM fiber”) 104. The GI fiber lens 105 having been cut off is fused and connected. One optical fiber with a tip lens is mounted on one substrate 103a, and the total reflection mirror 106 is mounted on the lens mounting end surface side of the substrate 103a with the lens end removed. Four optical fibers with a tip lens are mounted on the other substrate 103b, and a band-pass filter 107 is attached to one end face thereof. The band-pass filter 107 is composed of a plurality of laminated dielectric multilayer films, and the dielectric multilayer films continuously change in thickness in a certain direction. This dielectric multilayer film has different wavelengths of light to be reflected and transmitted depending on the location, so that different wavelength light can be reflected and transmitted at the end of each optical fiber with a lens. In this multi-core type optical demultiplexer, the multi-wavelength light (λ1 + λ2 + λ3 + λ4) incident from the optical fiber with the tip lens of one substrate 103a is used, and the tip lens of the other substrate 103b having the bandpass filter 107 attached to one end surface. By entering the attached optical fiber, the wavelengths λ1, λ2, λ3, and λ4 can be demultiplexed in order and extracted. (For example, refer to Patent Document 1.)
Japanese Patent Laid-Open No. 11-190809

  However, since such an optical multiplexer / demultiplexer needs to connect two substrates 3a and 3b, there is a problem that adjustment of the optical axis, that is, alignment is difficult, and it takes time to manufacture. In addition, since the optical fibers for incidence and emission are respectively arranged at both ends of the optical multiplexer / demultiplexer, there is a problem that miniaturization is difficult.

  The present invention has been made to solve the above problems, and an object thereof is to provide an optical filter module that is small in size and easy to align.

  A first optical filter module according to the present invention includes a first optical fiber and a plurality of second optical fibers each having a GI fiber at one end, and a plurality of reflective surfaces each reflecting light of a corresponding wavelength. And a filter substrate that is laminated so that the reflecting surfaces are parallel to each other, and the one end of each of the first optical fiber and each of the second optical fibers has each of the reflections The first optical fiber is optically connected to the filter substrate on the same side with respect to the surface, and the first optical fiber is disposed so that an axial direction thereof is an angle α with respect to a direction perpendicular to the reflecting surfaces. The plurality of second optical fibers are on the same plane as the first optical fiber and are opposite to the first optical fiber with respect to the direction perpendicular to the reflecting surfaces, and the axial direction of the second optical fibers is the same as the first optical fiber. Are arranged such that the angle α with respect to a direction perpendicular to the morphism surface.

  Preferably, in the first optical filter module, each of the reflecting surfaces reflects light of a corresponding wavelength among incident light on one corresponding substrate among the plurality of substrates, Each is formed by attaching a dielectric multilayer film that transmits light of a wavelength. This optical filter module is referred to as a second optical filter module.

  The third optical filter module according to the present invention has a first optical fiber and a plurality of second optical fibers each having a GI fiber at one end, and a plurality of transmission regions through which light of the corresponding wavelength is transmitted. A filter substrate having a transmission surface and a total reflection surface facing the transmission surface, wherein the one end portion of the first optical fiber and each of the second optical fibers is formed on the filter substrate. Each of the first optical fibers is optically connected to the transmission surface, and the axial direction of the first optical fiber is disposed at an angle α with respect to a direction perpendicular to the transmission surface of the filter substrate. The plurality of second optical fibers are arranged on the same plane as the first optical fiber, on the opposite side of the first optical fiber with respect to the direction perpendicular to the transmission surface of the filter substrate, There are respectively arranged such that an angle α with respect to a direction perpendicular to the light transmitting surface of the filter substrate.

  Preferably, in the third optical filter module, the transmission surface transmits a plurality of dielectrics that transmit light of a corresponding wavelength among light incident on the filter substrate and reflect light of other wavelengths. Each of the body multilayer films is attached. This optical filter module is referred to as a fourth optical filter module.

  Preferably, in any one of the first to fourth optical filter modules, the first optical fiber and each of the second optical fibers are optically attached to the filter substrate at one end portion thereof via an adhesive. Are connected to each. This optical filter module is referred to as a fifth optical filter module.

  Preferably, in any of the first to fourth optical filter modules, each of the first optical fiber and the second optical fiber includes a third optical fiber coupled to a tip of the GI fiber. This optical filter module is referred to as a sixth optical filter module.

  Preferably, in the sixth optical filter module, the third fiber is a coreless fiber. This optical filter module is referred to as a seventh optical filter module.

  Preferably, in the sixth or seventh optical filter module, end faces of the first tip portions of the first optical fiber and the second optical fibers are inclined by an angle α with respect to the axial direction. ing. This optical filter module is referred to as an eighth optical filter module.

  Preferably, in any one of the sixth to eighth optical filter modules, optical path lengths between the GI fiber in the first optical fiber and the GI fiber in each of the second optical fibers are equal to each other. Thus, the length of the third optical fiber of each of the second optical fibers is set.

  According to the optical filter module of the present invention, since the first optical fiber, the second optical fiber, and the filter substrate can be arranged on the same substrate, the position of each optical fiber and the filter substrate can be adjusted slightly. A structure with easy alignment can be realized. Further, since the incident and exit optical fibers are on the same side with respect to the reflection surface or transmission surface of the filter substrate, a small optical filter module can be realized.

  Exemplary embodiments of a reflective optical filter module of the present invention will be described below in detail with reference to the accompanying drawings.

(First embodiment)
1A and 1B are diagrams showing a configuration example of a reflective optical filter module according to a first embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a side view. As shown in FIG. 1, in the reflection type optical filter module 1 according to the present embodiment, four optical fibers 2a, 2b, 2c, and 2d are fixedly mounted on a mounting substrate 3, respectively. Each optical fiber 2 a, 2 b, 2 c, 2 d has one end of a GI fiber 4 having a predetermined length attached to one end of the SM fiber 5 by fusion splicing, and the coreless fiber 6 is attached to the other end of the GI fiber 4. Are formed by fusion splicing by the same means. The mounting substrate 3 has V-groove, U-groove or rectangular groove-shaped optical fiber fixing grooves on the upper surface, and corresponding optical fibers 2a, 2b, 2c, 2d are fixedly mounted in the respective optical fiber fixing grooves. ing. Here, the optical fibers 2b, 2c, and 2d are fixedly mounted so that the angle in the axial direction of each optical fiber 2b, 2c, and 2d with respect to the axial direction of the optical fiber 2a is 2α. A filter substrate 8 is disposed on the mounting substrate 3. Then, one surface of the filter substrate 8 is disposed so as to be perpendicular to the direction of the angle α with respect to the axial direction of the optical fiber 2a. That is, the end face of the coreless fiber 6 of the optical fiber 2a is inclined by an angle α with respect to the axial direction of the optical fiber 2a. The tip of each optical fiber 2a, 2b, 2c, 2d on the coreless fiber 6 side is bonded to the one surface of the filter substrate 8, respectively. Here, the filter substrate 8 is formed by closely laminating three filter elements 9a, 9b, and 9c as one optical element. In the following description, the optical fibers 2a, 2b, 2c, and 2d may be simply described as “optical fiber 2” without distinction. Further, the filter elements 9a, 9b, and 9c may be simply described as “filter element 9” without being distinguished.

  FIG. 2 is an enlarged view of an optical connection portion in the multi-branch reflection type optical module 1 shown in FIG. As shown in FIG. 2, each filter element 9a, 9b, 9c is made of a substrate having a surface on which a corresponding dielectric multilayer film 10a, 10b, 10c is formed. The substrates constituting the filter elements 9a, 9b, and 9c are laminated so that the dielectric multilayer films 10a, 10b, and 10c are parallel to each other. The optical fibers 2a, 2b, 2c, and 2d The body multilayer films 10a, 10b, and 10c are arranged so as to have an angle α with respect to a direction perpendicular to the surface direction. The optical fiber 2a and the optical fibers 2b, 2c, 2d are disposed on the opposite sides with respect to the direction perpendicular to the surface direction of the dielectric multilayer films 10a, 10b, 10c. Here, the three substrates constituting the filter elements 9a, 9b, 9c are each a rectangular substrate, and the dielectric multilayer film 10 is formed on one of the two opposing main surfaces of each substrate. The surface of the filter substrate 8 to which the tip ends of the optical fibers 2a, 2b, 2c, and 2d are joined is parallel to the surface direction of the dielectric multilayer film 10. Hereinafter, the dielectric multilayer films 10a, 10b, and 10c may be simply referred to as “dielectric multilayer film 10” without being distinguished from each other.

  FIG. 3 is a diagram showing the wavelength-reflection characteristics of the dielectric multilayer films 10a, 10b, and 10c. As shown in FIG. 3, the dielectric multilayer film 10a is a bandpass filter having a center wavelength of λ1 and a reflection wavelength band of ω1, and the dielectric multilayer film 10b has a center wavelength of λ2 and a reflection wavelength band of ω2. The dielectric multilayer film 10c is a bandpass filter having a center wavelength of λ3 and a reflection wavelength band of ω3. The dielectric multilayer films 10a, 10b, and 10c constituting each filter are generally filter elements 9a that alternately correspond to a thin film medium such as TiO 2 with a high refractive index having a film thickness of λ / 4 and a SiO 2 thin film medium with a low refractive index. , 9b, and 9c, and a narrow band or wide band characteristic can be obtained by slightly shifting the film thickness from λ / 4 or forming a multilayer film with different film thicknesses. Can do. The dielectric multilayer film 10 can be handled as a single multilayer film without being formed on the filter element 9.

  The filter element 9a having a thickness T1 having the dielectric multilayer film 10a reflects light having an incident angle of α and a wavelength of λ1 ± ω1 / 2 and transmits light of other wavelengths. The filter element 9b having the thickness T2 having the dielectric multilayer film 10b reflects light having an incident angle of α and a wavelength of λ2 ± ω2 / 2 and transmits light of other wavelengths. Further, the filter element 9c having a thickness T3 having the dielectric multilayer film 10c reflects light having a wavelength of λ3 ± ω3 / 2 and transmits light of other wavelengths. Here, the filter substrate 8 is configured as a multilayer filter substrate having a thickness (T1 + T2 + T3) by closely laminating filter elements 9a, 9b, and 9c. As a means for laminating each filter element 9a, 9b, 9c, there is a method using adhesion with a translucent UV adhesive, surface activated room temperature bonding, low-melting glass attachment, or the like. In the reflection type optical filter module 1 according to the present embodiment, the filter substrate 8 is obtained by stacking the filter elements 9a, 9b, and 9c to obtain a large filter substrate, and then cutting it into small pieces with a dicing saw. Can be obtained.

  As shown in FIG. 2, three wavelengths of light (λ1 + λ2 + λ3) are incident on the optical fiber 2a. The outgoing collimator light emitted from the GI fiber 4 in the optical fiber 2a enters the filter element 9a and enters the bandpass filter of the mounted dielectric multilayer film 10a at an incident angle α. The light having the wavelength λ1 incident on the dielectric multilayer film 10a is reflected at the reflection angle α and enters the coreless fiber 6 of the optical fiber 1b. Of the light having the wavelengths λ2 and λ3 transmitted through the dielectric multilayer film 10a, the light having the wavelength λ2 is reflected at the reflection angle α by the dielectric multilayer film 10b of the filter element 9b and enters the coreless fiber 6 of the optical fiber 1c. . The light of wavelength λ3 transmitted through the dielectric multilayer film 8b is reflected at the reflection angle α by the dielectric multilayer film 10c of the filter element 9c, and enters the coreless fiber 6 of the optical fiber 1d.

In this case, the distance on the central axis between the GI fiber 4 in the optical fiber 2a and the GI fiber 4 in the optical fiber 2b is W1, the central axis between the GI fiber 4 in the optical fiber 2a and the GI fiber 4 in the optical fiber 2c. If the upper distance is W2, and the distance on the central axis between the GI fiber 4 in the optical fiber 2a and the GI fiber 4 in 2d is W3, each optical fiber 2a, 2b, 2c, 2d It is fixed to the mounting substrate 3 so that the relationship of Expression (1) is established. It is assumed that the refractive index of the coreless fiber 6 and the filter substrate 8 are both made of quartz and have substantially the same refractive index.

Since W1, W2, and W3 can be regarded as twice the working distance WD of the GI fiber 4 to be used, Wn = 2WD (n = 1 to 3) is established. Considering the paraxial ray approximation, the working distance WD is expressed by the following equation (2).

The GI fiber 4 used here is manufactured by a method of manufacturing a gradient index multimode optical fiber, the core diameter is larger than the cladding diameter, and the outer diameter ratio is 1 for the cladding diameter. The core diameter is 0.9 or more, and the cladding diameter is about 125 to 500 μm. The basic optical characteristic of the GI fiber 4 is similar to a gradient index lens, and its length Z is determined so as to satisfy the relationship of the following formula (3).

  In the case of the reflection type optical filter module 1 according to the present embodiment, the optical fiber 2 using the GI fiber 4 having a pitch length of P> 0.25 is used. The coreless fiber 6 is a quartz optical fiber having only a cladding portion without a core, and has an outer diameter of about 125 to 500 μm.

  FIG. 4 shows a manufacturing method of the reflection type optical filter module according to the present embodiment using the optical fiber 2, and FIGS. 4A and 4B are diagrams for explaining a manufacturing process of the optical fiber 2. It is. As shown in (a), a SM fiber 5 having a predetermined length, a GI fiber 4 cut to a predetermined length, and a coreless fiber 6 cut to a certain length are prepared. Each fiber can be cut using a normal fiber cutter and a length setting jig. Next, one end of the SM fiber 5 and one end of the GI fiber 4 are fusion-spliced by a fusion splicer. Then, the fusion-connected GI fiber 4 is cut into a predetermined length Z with high accuracy by a fiber cutter. Next, the coreless fiber 6 is fused and connected to the GI fiber 4 and cut to a predetermined length by a fiber cutter. Thereby, the optical fiber 2 shown in (b) can be configured. Next, as shown in (c), the four optical fibers 2 are prepared, and mounted and fixed at predetermined positions of the fixing groove portion of the mounting substrate 3, respectively. The fixing position of each optical fiber 2 in the fixing groove is determined by previously cutting the slit on the mounting substrate 3 at an angle α with respect to the side surface of the substrate as a reference position. It can be set from the length between the two GI fibers 4. Thereafter, the right side portion of the slit of the substrate 3 is flatly removed to a predetermined depth by a dicing saw or the like to form the terrace portion 11 on which the filter substrate 8 is installed and fixed, and each optical fiber located at the right side portion of the slit is formed. Cut 2 sites. Then, the filter substrate 8 is installed and fixed in a state in which the filter substrate 8 is in close contact with the wall where the end of the coreless fiber 6 is exposed at the portion of the substrate 3 where the slit right side portion is removed. At this time, it is possible to accurately position the filter substrate 8 by installing the filter substrate 8, monitoring each reflected light to the optical fibers 2 b, 2 c, 2 c and finely adjusting the position of the filter substrate 8. . Further, the mounting substrate 3 to which the filter substrate 8 is fixed is fixed in a cylindrical or rectangular mounting case, and the input / output fiber insertion portion is sealed to produce a reflection type optical filter module.

  According to the optical filter module 1 according to the present embodiment, a mounting structure with easy alignment can be realized simply by connecting the filter substrate to the end of the coreless fiber and slightly adjusting it. In addition, since the incident optical fiber 2a and the outgoing optical fibers 2b, 2c, and 2d can be arranged on the same side with respect to the filter substrate, a small reflective optical filter module can be realized. Can do.

  Further, according to the optical filter module 1 according to the present embodiment, the coreless fiber 6 is connected to one end of the GI fiber 4 and the coreless fiber 6 is connected to the filter substrate 8, so that the end of the GI fiber 4 is inclined. And no increase in aberration occurs. For example, in the conventional multi-core filter module shown in FIG. 7, since the reflected light is used for demultiplexing, it is necessary to incline the end surfaces of the opposing substrates 103a and 103b, and at the same time, the GI fiber 104 Since it is necessary to incline the end portion, there is a problem in that the lens function of the shaved portion is deleted, thereby increasing aberrations and increasing optical loss. According to the optical filter module 1 according to the present embodiment, such an increase in optical loss can be prevented.

  Further, according to the optical filter module 1 according to the present embodiment, the coreless fiber 6 is connected to the tip of the GI fiber 4, so that the working distances W <b> 1, W <b> 2, W <b> 3 between the GI fibers 4 depend on the length of the coreless fiber 6. Therefore, it is possible to connect the GI fibers 4 with low loss.

  In the optical filter module 1 according to the present embodiment, the coreless fiber 6 is connected to the tip of the GI fiber 4. However, the present invention is not limited to this, and a fiber made of a translucent resin having the same refractive index as that of the coreless fiber 6 is connected. May be.

  In the optical filter module 1 described above, the coreless fiber 6 is connected to the end of the GI fiber 4 and the end of the coreless fiber 6 is connected to the filter substrate 8. You may connect to the filter board | substrate 8 through an adhesive bond layer. Even in such a case, the end of the GI fiber 4 is not inclined, and an increase in aberration can be prevented. In order to appropriately adjust the working distances W1, W2, and W3 between the GI fibers 4, it is more preferable to use a fiber such as the coreless fiber 4 than an adhesive.

(Second Embodiment)
FIG. 5 is a plan view showing a configuration example of a reflective optical filter module according to the second embodiment of the present invention. The reflective optical filter module according to the present embodiment is different from the reflective optical filter module 1 according to the first embodiment in that the filter substrate 22 to be used is not a multilayer but a single layer. That is, a band pass filter composed of each dielectric multilayer film 10a, 10b, 10c is mounted adjacent to one main surface of the substrate. The mounting can be performed by using a translucent adhesive, but other methods such as surface activated room temperature bonding may be used. The other principal surface of the substrate is a total reflection mirror surface made of a dielectric multilayer film, and reflects light of wavelengths λ1, λ2, and λ3 incident from the incident optical fiber 1a. In this case, the characteristic of the dielectric multilayer film 10 is different from that of the embodiment of FIG. 1, and the dielectric multilayer film 10a transmits light of wavelength λ1 and reflects light of other wavelengths. The dielectric multilayer film 10b transmits light of wavelength λ2 and reflects light of other wavelengths. The dielectric multilayer film 10c reflects light having a wavelength λ3 and reflects light having other wavelengths. That is, the reflectance η in the graph of FIG.

  As shown in FIG. 5, in the reflective optical filter module 21 according to the present embodiment, the light incident from the optical fiber 2a reaches the total reflection surface and is reflected by the total reflection surface. Then, the reflected light is incident on the dielectric multilayer film 10a, the light of wavelength λ1 is transmitted through the dielectric multilayer film 10a, and the light of other wavelengths is reflected again toward the total reflection surface. The light that reaches the total reflection surface is reflected and enters the dielectric multilayer film 10b, the light of wavelength λ2 is transmitted through the dielectric multilayer film 10b, and the light of other wavelengths is reflected again toward the total reflection surface. Is done. Further, the light that has reached the total reflection surface is reflected and enters the dielectric multilayer film 10c, and the light having the wavelength λ3 is transmitted through the dielectric multilayer film 10c. Each optical fiber 2b, 2c, 2d is joined to the corresponding dielectric multilayer film 10a, 10b, 10c so that the light of the corresponding wavelength is incident respectively.

  FIG. 6 shows the pitch length of the GI fibers 4 to be used and the intervals (coreless fiber lengths) between the GI fibers 4 when the coreless fibers 6 are connected to the GI fibers 4, respectively. It can be seen that the smaller the core diameter is, the larger the interval between the GI fibers 4 is. In the optical filter modules according to the first and second embodiments, the loss between the GI fibers 4 is equalized according to the pitch length of the GI fibers 4 to reduce the loss. Referring to FIG. 6, for example, when using a GI fiber 4 having Δ = 0.7% and a core diameter of 120 μm, when the length of the GI fiber (GIF length) is 900 μm, the GI fiber 4 in the quartz medium The optimum value of the intervals W1, W2, W3, that is, 2WD (working distance) is 3000 μm. As described above, the necessary intervals W1 to W3 of the GI fiber 4 may be set using the length of the GI fiber 4 from the graph of FIG.

  Next, the reflection type optical filter module according to the first embodiment was actually prototyped based on FIG. A SM fiber 5 having a predetermined length, a coreless fiber 6, Δ = 0.7%, and a GI fiber 4 having a core diameter of 120 μm are prepared, and the GI fiber is connected to one end of the SM fiber 5 along the process shown in FIG. 4 was fused and the GI fiber 4 was cut at a length Z = 900 μm ± 20 μm. Then, the coreless fiber 6 was fused and connected to the cut cross section, and the coreless fiber 6 was cut at a location of about 2 mm in length to configure the optical fiber 2. Then, 12 optical fibers 2 configured in this way were prepared. From FIG. 6, the optimum length of the quartz medium of the optical fiber 2, that is, the coreless fiber between the GI fibers is 3000 μm.

Next, the substrate 3 has a predetermined shape (length 10 mm, width 4 mm, height 2 mm), has four V-grooves (α = 6 °), and slits having an angle α on the filter fixing surface. Three quartz substrates 3 with cuts were prepared. Further, three filter elements 9 each having a different dielectric multilayer film 10a, 10b, 10c deposited on one main surface of a quartz substrate having a thickness of 0.4 mm are prepared, and these are prepared with a translucent adhesive. A large number of laminates were cut and cut into small pieces (approximately 0.75 to 1 mm) with a dicing saw. Here, the center wavelength of each filter composed of the dielectric multilayer film 8 is:
λ1 = 1310 nm (ω1 = ± 50 nm) λ2 = 1495 nm (ω2 = ± 5 nm)
λ3 = 1555 nm (ω3 = ± 5 nm).

Next, the optical fibers 2 were respectively fixed and mounted in four V-grooves. At this time, based on the equation (1) with reference to a slit cut to a small width at an angle α, a place where L1 = 0.4 mm, L2 = 1.8 mm, L3 = 1.0 mm, L4 = 0.2 mm Next, the GI fiber 4 was fixed with an ultraviolet curable adhesive and mounted. Next, a terrace portion for fixing and mounting the filter substrate 8 was processed. The cutting was performed by cutting a portion of the cutting region 11 at a depth of 0.8 mm along a groove having an angle α with a dicing saw to form a terrace portion on which the filter substrate 8 is fixedly mounted. Next, the filter 3 was placed on the terrace portion, and was tightly fixed to the wall at an angle α via a UV adhesive. At this time, the position of the filter substrate 8 may be optimized by fine fine adjustment while monitoring the outputs of the P2, P3, and P4 ports as necessary. In order to stabilize the fixing adhesive, it was allowed to stabilize at a predetermined temperature for a certain period of time. Next, the substrate 3 on which the filter substrate 8 is mounted is mounted on a cylindrical metal case having a length of 17 mm and an outer diameter of 5 mm, the input / output fiber 2 is sealed, and three evaluation samples (S1, S2, S3) )completed. The case may be rectangular instead of cylindrical. Table 1 shows optical characteristics of these evaluation samples S1 to S3 at normal temperature (25 ° C.).

As shown in Table 1, the insertion loss of the evaluation samples S1 to S3 is 0.28 to 0.49 dB, and compared with 2.1 to 2.8 dB of the embodiment shown in FIG. Is greatly reduced. Further, it was shown that the polarization dependence is 0.1 dB or less and the return loss is 50 dB or more, which has practically sufficient characteristics. Further, it is a reflection type optical filter module, and the mounting case length is as small as 17 mm, and the fiber extra length processing is only required on one side, so that it is possible to reduce the size for mounting.

It is the figure which showed the Example of the reflection type optical filter module by the 1st Embodiment of this invention, (a) is a top view, (b) is a side view. It is the figure which expanded and showed the filtering part of the reflection type optical filter module shown in FIG. It is the graph which showed the example of the characteristic of the dielectric multilayer used for the reflection type optical filter module by a 1st embodiment. It is the figure which showed an example of the manufacturing process of the reflection type optical filter module shown in FIG. 1, (a), (b) showed each GI fiber manufacturing process, (c) showed the board | substrate mounting of GI fiber. FIG. It is the top view which showed the structural example of the reflection type optical filter module by the 2nd Embodiment of this invention. It is the graph which showed the relationship between the GI fiber length used for the reflection type optical filter module of this invention, and the optimal GI fiber space | interval in a quartz medium. It is the figure which showed the Example of the conventional multi-core type filter module.

Explanation of symbols

1. 1. Optical filter module 2. Optical fiber 3. Mounting board 4. GI fiber SM fiber Coreless fiber8. Filter substrate 9. Filter element 10. 10. Dielectric multilayer film Terrace section

Claims (9)

A first optical fiber and a plurality of second optical fibers each having a GI fiber at one end;
A plurality of substrates each having a reflecting surface that reflects light of a corresponding wavelength, and a filter substrate that is laminated so that the reflecting surfaces are parallel,
The one end portions of the first optical fiber and the second optical fibers are optically connected to the filter substrate on the same side with respect to the reflecting surfaces, respectively.
The first optical fiber is disposed such that an axial direction thereof is an angle α with respect to a direction perpendicular to the reflecting surfaces,
The plurality of second optical fibers are on the same plane as the first optical fiber, opposite to the first optical fiber with respect to the direction perpendicular to the reflecting surfaces, and the axial direction is perpendicular to the reflecting surfaces. The optical filter module is arranged so as to be at an angle α with respect to the optical filter module.   Each of the reflective surfaces is attached to a corresponding one of the plurality of substrates by a dielectric multilayer film that reflects light having a corresponding wavelength among incident light and transmits light having another wavelength. The optical filter module according to claim 1, wherein each of the optical filter modules is configured as follows. A first optical fiber and a plurality of second optical fibers each having a GI fiber at one end;
A filter substrate having a transmission surface having a plurality of transmission regions each transmitting light of a corresponding wavelength, and a total reflection surface facing the transmission surface;
With
The one end portion of the first optical fiber and each of the second optical fibers is optically connected to the transmission surface of the filter substrate, respectively.
The first optical fiber is disposed such that an axial direction thereof is an angle α with respect to a direction perpendicular to the transmission surface of the filter substrate,
The plurality of second optical fibers are on the same plane as the first optical fiber, opposite to the first optical fiber in a direction perpendicular to the transmission surface of the filter substrate, and an axial direction of the second optical fiber is the filter substrate. An optical filter module, wherein the optical filter modules are arranged at an angle α with respect to a direction perpendicular to the transmission surface.   The transmission surface is formed by attaching a plurality of dielectric multilayer films that transmit light of a corresponding wavelength among incident light and reflect light of other wavelengths on the filter substrate. The optical filter module according to claim 3.   5. The first optical fiber and each of the second optical fibers, wherein the one end is optically connected to the filter substrate via an adhesive, respectively. The optical filter module in any one.   5. The optical filter according to claim 1, wherein each of the first optical fiber and each of the second optical fibers includes a third optical fiber coupled to a tip of the GI fiber. module.   The optical filter module according to claim 6, wherein the third optical fiber is a coreless fiber.   8. The end face of the one end portion of each of the first optical fiber and each of the second optical fibers is inclined by an angle α with respect to the axial direction thereof. Optical filter module.   The lengths of the third optical fibers of the second optical fibers are set so that the optical path lengths between the GI fibers of the first optical fibers and the GI fibers of the second optical fibers are equal to each other. The optical filter module according to claim 6, wherein the optical filter module is provided.

Images