JP2006284767A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it easy to manufacture an optical module while the optical module can be made small in size and integrated. <P>SOLUTION: The optical module has a ferrule having 1st and 2nd through holes passing through front and rear end surfaces, a 1st optical fiber disposed on a rear end surface side of the 1st through hole, a 1st coreless fiber disposed on a front end surface side of the 1st through hole, a 1st optical path which is disposed between the 1st optical fiber and the 1st coreless fiber in the 1st through hole and has a 1st GI fiber shaping light projected from the 1st optical fiber into a parallel light beam and making it incident on the 1st coreless fiber, a 2nd optical fiber disposed on a rear end surface side of the 2nd through hole, a 2nd coreless fiber disposed on a front end surface side of the 2nd through hole, a 2nd optical path which is disposed between the 2nd optical fiber and the 2nd coreless fiber in the 2nd through hole and has a 2nd GI fiber shaping light projected from the 2nd optical fiber into a parallel light beam and making it incident on the 2nd coreless fiber, and a reflection type optical functional element which reflects and/or transmits the light projected from the 1st optical path through its function and makes it incident on the 2nd optical path. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical module configured using an optical fiber, and more particularly to an optical module used for an optical communication component, an optical sensor, or the like.

  Various studies have been made toward miniaturization and integration of optical circuits of optical communication devices. For example, Patent Documents 1 and 2 disclose a reflective optical module that can shorten the length of an optical system portion by installing an input / output optical fiber on one side of an optical functional element. This conventional reflection-type optical module is effective in reducing the size of the optical circuit because the mounting area required for the extra fiber length processing outside the module is about half that of the in-line type optical module.

  In the reflection-type optical module of Patent Document 1, a reflection plate is installed on a substrate so as to be inclined with respect to the fiber optical axis, and an optical element or a lens is disposed between the reflection plate and the fiber. In this conventional example, it is possible to easily configure a reflective optical system having a plurality of functions, to reduce the mounting space, and to reduce the optical circuit mounting area by about 40% compared to the case where an inline optical module is used. Has been.

In addition, the reflection type optical module disclosed in Patent Document 2 uses a core expansion fiber in a lens system, and an optical element having a certain thickness is brought into close contact with the optical element by facing the optical element at a certain angle. It is effective as a means for integrating the reflection type optical modules.
JP 2004-206052 A JP-A-11-101920

However, the conventional reflection type optical module shown in Patent Document 1 requires assembly of the lens to the optical fiber and the optical element to the lens at a predetermined angle. There was a problem that it took time and effort.
Further, in the conventional reflection type optical module disclosed in Patent Document 1, it is difficult to further miniaturize and integrate.

In the conventional example in which the core expansion fiber is used in the lens system disclosed in Patent Document 2, the core expansion fiber must be expanded to about 35 to 40 μm in order to input and output light close to parallel light as a fiber collimator. There was a problem that the production involved a lot of difficulties and labor.
In addition, in order to achieve low-loss coupling, the optical distance between connecting fibers cannot be 1 mm or more, so the thickness of the optical element to be used is limited, and there is a certain limitation in the selection of the optical element. There was a point.

  Therefore, an object of the present invention is to provide an optical module that can be miniaturized and integrated and can be easily manufactured.

In order to achieve the above object, an optical module according to the present invention includes a front end surface, a rear end surface, and a ferrule having first and second through holes penetrating from the front end surface to the rear end surface, respectively.
The first optical fiber located on the rear end face side of the first through hole, the first coreless fiber located on the front end face side of the first through hole, and the first through hole in the first through hole. A first graded index fiber that is positioned between an optical fiber and the first coreless fiber and that enters the first coreless fiber by making light emitted from the first optical fiber into parallel rays; A first optical path,
The second optical fiber located on the rear end face side of the second through hole, the second coreless fiber located on the front end face side of the second through hole, and the second through hole in the second through hole. A second graded index fiber that is located between the optical fiber and the second coreless fiber and that enters the second coreless fiber by making the light emitted from the second optical fiber into parallel rays. A second optical path,
And a reflective optical functional element that reflects and / or transmits light emitted from the first optical path based on its function and then enters the second optical path.

  According to the optical module of the present invention configured as described above, an optical module that can be miniaturized and integrated and can be easily manufactured can be provided.

Embodiments according to the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the configuration of the optical module according to Embodiment 1 of the present invention. The first optical path on the input side and the second optical path on the output side, which are integrally configured using a two-core ferrule 4 And the reflective optical functional element 7.
In the first embodiment, the ferrule 4 has two through holes penetrating in the longitudinal direction, the first optical path is configured by using one through hole, and the second optical path is formed by using one through hole. An optical path is constructed. In the present specification, the end face of the ferrule 4 facing the reflective optical functional element 7 is referred to as a front end face, and the opposite end face is referred to as a rear end face.

  In the first embodiment, the two through holes are formed parallel to the long axis of the ferrule 4 and separated from the optical axis by the same distance. Further, the front end surface of the ferrule 4 has a wedge shape including two first and second surfaces having different directions, the opening of one through hole is on the first surface, and the opening of the other through hole Is on the second side. Further, in the first embodiment, the first surface and the second surface are inclined at the same angle θ with respect to the surface orthogonal to the major axis of the ferrule 4.

In the first embodiment, the first optical path contacts the optical fiber 3 inserted into one through-hole of the ferrule from the rear end surface side and the front end of the optical fiber 3 inserted into one through-hole from the front end surface side. A graded index fiber (hereinafter referred to as GI fiber) 1 that is in contact with the coreless fiber 2 that is inserted into one through hole from the front end face side and abuts against the tip of the GI fiber 1 is constituted.
Here, in the first optical path, the GI fiber 1 is processed to a predetermined length as will be described later, and the light emitted from the tip of the optical fiber 3 is converted into parallel rays and emitted through the coreless fiber 2. The Further, the exit end face of the coreless fiber 2 is inclined with respect to a plane orthogonal to the axis of the ferrule 4 so that the light parallel to the GI fiber 1 is emitted toward the incident portion of the reflective optical function element 7. Is formed.

Further, the second optical path includes an optical fiber 3 inserted into the other through-hole of the ferrule from the rear end surface side, and a GI fiber 1 inserted into the other through-hole from the front end surface side and contacting the front end of the optical fiber 3. The coreless fiber 2 is inserted into the other through hole from the front end face side and abuts against the tip of the GI fiber 1.
Here, in the second optical path, the GI fiber 1 is processed to a predetermined length, condenses the light incident through the coreless fiber 2, and passes from the core portion at the tip of the optical fiber 3 to the optical fiber. 3 is incident. The exit end face of the coreless fiber 2 is inclined with respect to a plane orthogonal to the axis of the ferrule 4 so that light from the reflective optical functional element 7 is efficiently incident on the GI fiber 1 through the coreless fiber 2. Is formed.

In the first embodiment, the reflective optical functional element 7 is a wavelength selective filter element configured to reflect a predetermined light of incident light on the surface thereof, and the incident / reflection portion of the ferrule 4 It is located on the extension line of the axis, and is arranged so that the incident surface of the reflective optical functional element 7 is orthogonal to the extension line.
For example, when the light of wavelength (λ1 + λ2) is incident from the first optical path, the wavelength selective filter element reflects only the light of wavelength λ1, and the light of wavelength λ1 is output through the second optical path. The

  Next, the distance between the reflective optical functional element 7 and the ferrule 4 in the optical device of the first embodiment configured as described above, and the inclination angle θ between the first surface and the second surface on the front end surface of the ferrule 4 are as follows. The setting method is described.

In the first embodiment, for example, the propagating light beam that has propagated through the optical fiber 3 that is a single-mode fiber that is a fiber having an outer diameter of 125 μm is converted into collimator light (parallel light) by the GI fiber 1, and the coreless fiber 2 is It propagates and exits in the direction of angle β with respect to the optical axis from the exit surface inclined by an angle θ with respect to the direction perpendicular to the optical axis.
Here, the coreless fiber 2 is composed only of a clad portion made of quartz and having no core. When the refractive index of the coreless fiber is n1 and the refractive index of the exit side medium is n3, the exit angle β is expressed by the following formula ( Given in 1).
β = sin ⁻¹ {(n1 / n3) · sin θ} −θ (1)

  As can be seen from this equation (1), if the refractive index n1 of the coreless fiber 2 is large, the emission angle β can be made large. Moreover, the refractive index n1 can be adjusted in the range of 1.45-1.8 by putting the additive which increases refractive indexes, such as Ge, in a coreless fiber.

In the first embodiment, the distance D between the fibers 3 (through holes) of the two-core ferrule 4 is given by the following equation (2), and the distance D must be at least equal to or greater than the cladding diameter Cd of the optical fiber 3. . Note that the distance D is the distance between the optical axes of the optical fibers 3.
D = 2L · tan β ≧ Cd (2)

  Thus, in Embodiment 1 according to the present invention, in the present invention, the interval D of the optical fibers 3 is equal to the fiber clad diameter Cd, that is, the input / output optical fibers 3 are in close contact with each other. Is also possible.

In this regard, in the configuration of Patent Document 1, the lens is installed obliquely, and in the configuration of Patent Document 2, since the fiber is inclined at an angle θ2, in the conventional example, the input and output optical fibers are in close contact with each other. And cannot be configured.
Therefore, the optical device according to the first embodiment can realize an optical module that is smaller and more integrated than the conventional example.

  Next, the GI fiber 1 of the first embodiment will be described in detail. The GI fiber is a gradient index optical fiber, and when cut to a predetermined length, it becomes a lens having a focal length corresponding to the length.

Here, in particular, the GI fiber 1 is an optical fiber having an axially symmetric refractive index profile, and has a substantially squared refractive index profile.
For example, assuming that the refractive index distribution n (r) in the radial direction of the core of the GI fiber 1, the refractive index distribution is set so as to satisfy the following expression (3).
n (r) = n0 (1-A / 2r ² ) (3)
Here, a ≧ r ≧ 0, n0 is the refractive index on the core optical axis, A is the convergence constant, and a is the radius of the core.
The convergence constant A is given by the following equation (4).
A = {α0 · (α0−1) · Δ} / (a) ^α0 (4)
Α0 is a refractive index distribution constant, and is usually set to around 2.
Δ is the relative refractive index of the GI fiber, and is given by the following equation (5).
Δ = {n0−n (a)} / n0 (5)
Here, n (a) is the refractive index of the core outer peripheral surface of the GI fiber.

  By cutting such a GI fiber at the required length Z (by adjusting the GI fiber length (pitch length P) used inside), the necessary focal length and working distance can be obtained and necessary Therefore, it can be used as a gradient index lens. Further, by using the GI fiber 1 having a cladding outer diameter of 125 μm and a core diameter of about 100 μm, the single mode fiber 3 and the coreless fiber 2 having the same cladding diameter can be fused and used.

  FIG. 3 shows an example of ray tracing in the GI fiber 1, which has a core diameter 2a and a cladding diameter Cd. In the core 11 of the GI fiber 2, almost the behavior of a sine curve is shown, the unit length of the horizontal axis is expressed by the pitch (P), the vertical axis indicates the position of the light beam in the GI fiber 1, The position where the light beam spreads most is shown as 1. Note that P = 1 corresponds to one period (2π) of the sine curve.

The period P and the lens length Z are given by the following equations (6) and (7), respectively.
P = 2π / √A (6)
Z = 2πP / √A (7)

When the distance between the end face of the GI fiber and the focal point is a focal length f, f is given by the following equation (8).
f = 1 / {n0 · √A · tan (√A · Z)} (8)

  Here, in order to convert light from a point light source into parallel light, a light having a length of P = 0.25 may be used. A length of P = 0.5 is a lens that focuses between the end faces. In order to function as a lens, a length between P = 0.05 and P = 0.5 is used.

  FIG. 4A shows the value of the focal length f when parallel light is incident on a GI fiber with P = 0.05 to 0.3. When the relative refractive index Δ of the GI fiber is larger, the focal length f is smaller, that is, the NA is larger, and the spot diameter at the focal point can be reduced. It can be seen that the GI fiber 1 having a large Δ value may be used when connecting to a fiber having a small core diameter. Further, the focal length is shortened as the pitch P is increased. When the GI fiber 1 near P = 0.25 is connected to the optical fiber 3, a light beam close to parallel light is emitted from the coreless fiber 2.

By using such a GI fiber 1, the first and second optical paths that are fiber collimators can be configured.
In the first embodiment, the first or second optical path has the coreless fiber 2 on one side of the GI fiber 1 that is cut to a predetermined length by removing the protective coating and exposing the cladding, and the single mode on the other side. As shown in FIG. 2, the fiber 3 is fusion spliced, mounted and fixed in the through hole of the ferrule 4, and easily manufactured by polishing the incident / exit side end face on the coreless fiber 2 side at an angle θ. .

In the optical module according to the first embodiment, since the first optical path and the second optical path including the optical fiber 3 and the GI fiber 1 having the function of the lens and the coreless fiber 2 are integrally formed on the ferrule 4, In comparison, the number of components can be reduced, and the number of parts that require assembly fixing of the optical element and position adjustment with the connecting fiber can be reduced. Therefore, it can be easily manufactured and can be miniaturized.
Therefore, an integrated small reflection type optical module having a composite function having a plurality of input / output ports can be realized.

In the first embodiment described above, the optical element 7 using the filter element has been described.
However, the present invention is not limited to this, and a reflective optical function capable of emitting the light incident from the first optical path toward the second optical path after reflecting and / or transmitting the light based on the function. An element can be used.
Examples of such a reflective optical functional element include a reflective optical isolator element, a Faraday rotator, a polarizer, a diffraction grating, and a total reflection mirror.

  For example, a reflection type Faraday rotator is produced by coating an AR coat on one surface of a garnet substrate whose thickness is set so that the polarization rotation angle is 45 °, and a reflective film on the other surface. The

In addition, as shown in FIG. 5, for example, the reflection type optical isolator is a Faraday rotation whose thickness is set on the magnet 102 so that the total reflection mirror 103 and the polarization plane are rotated by 22.5 °. It is configured by laminating a child 104, a glass plate 105 and polarizers 106 and 107.
The polarizers 106 and 107 are configured such that the parallel Nicols condition is shifted by 45 °.

In the optical isolator configured as described above, incident light transmitted through the polarizer 106 passes through the glass plate 105 and then enters the Faraday rotator 104. The incident light has its polarization plane rotated by 22.5 ° by the Faraday rotator 104, then totally reflected by the total reflection mirror 3, and the polarization plane is rotated by 22.5 ° again by the Faraday rotator 104. The Therefore, this light is rotated by 45 ° in total, and then passes through the glass plate 105 and enters the polarizer 107, so that the light passes through the polarizer 107 under the condition of parallel Nicols.
On the other hand, of the reflected light, the returned light that has been reflected by the end face of the optical component or scattered within the optical fiber is incident on the polarizer 107 of the optical isolator again. Of the return light that has entered the polarizer 107, only light that satisfies the parallel Nicols condition of the polarizer 107 passes through it and enters the optical isolator, but this light passes through the optical Faraday rotator 104 twice. This further rotates the plane of polarization by 45 °. Therefore, the return light is incident on the polarizer 106 with a vertical Nicol, and the return light is cut off.
The reflection type optical isolator is configured as described above.

Embodiment 2. FIG.
As shown in FIG. 6, the optical module according to the second embodiment of the present invention uses a one-core ferrule 5 and a two-core ferrule 6 having an inclination angle θ, and the input side has one port and the output side has two ports. This is an optical module of a 1 × 2 reflective optical system.
In the optical module of the second embodiment, the first optical path on the input side is configured using the single-core ferrule 5, and two second optical paths on the output side are configured using the two-core ferrule 6.
The first optical path and the second optical path are configured in the same manner as in the first embodiment.

  In the optical module according to the second embodiment, the optical functional element 7 is, for example, a reflective wavelength selection filter in which a filter film is deposited on both sides of the substrate, and the surface of the substrate (surface facing the ferrule) has a wavelength. A thin film filter 8 that reflects light of λ1 is formed, and a thin film filter 9 that reflects light of λ2 is formed on the bottom surface of the substrate.

In the optical module according to the second embodiment configured as described above, when light having a wavelength (λ1 + λ2) is incident from the first optical path configured by a single-core ferrule, the light having the wavelength λ1 is transmitted through the thin film filter 8 on the surface of the substrate. The light is reflected and enters one of the two second optical paths that is closer to the first optical path.
The light having the wavelength λ2 is transmitted through the substrate of the optical functional element and reflected by the thin film filter 9 formed on the bottom surface, and the second one of the two second optical paths is located away from the first optical path. Incident in two optical paths.

  In the optical module according to the second embodiment, the light having the wavelength λ1 and the light having the wavelength λ2 can be separated and obtained through the two second optical paths in this way.

In the optical module of the second embodiment, the distance d (interval between the second optical paths) between the through holes of the two-core ferrule 6 is given by the following equations (9) and (10).
d = 2t · tan γ (9)
γ = sin ⁻¹ {(n0 / n2) · sin β} (10)
Here, t is the thickness of the optical function element 7, and n2 is the refractive index of the optical function element 7.

Further, the inclination angle θ and the emission angle β of the end faces of the ferrules 5 and 6 may be set based on the same concept as described in the first embodiment.
In the optical module according to the second embodiment configured as described above, the fiber intervals D and d can be shortened by adjusting the tilt angle θ, the emission angle β, and the thickness t of the optical element 7, thereby reducing the size of the optical module. Modules can be provided.

Embodiment 3 FIG.
As shown in FIGS. 7A and 7B, the optical module according to the third embodiment of the present invention uses the ferrule 15 in which the ferrule 5 and the ferrule 6 are integrated in the optical module according to the second embodiment. One optical path and a second optical path are formed. Since the configuration of the first optical path and the second optical path, the configuration of the optical function element 7 and the method for setting the distance between the ferrule and the optical function element 7 are the same as those in the second embodiment, the description thereof is omitted.

In the third embodiment, the three-core fiber collimator unit and the optical function element 7 having a 1 × 2 input / output port configured using the integrated ferrule 15 are mounted on the substrate 10. It is stored in the case 11.
In the third embodiment, in order to mount the three-core fiber collimator unit and the optical functional element 7 on the substrate 10, a V groove or a rectangular groove is formed on the substrate 10 to be positioned and fixed. Good.

  According to the optical module of the third embodiment configured as described above, each fiber is adjusted by adjusting the inclination angle θ, the emission angle β, and the thickness t of the optical element 7 as in the optical module of the second embodiment. The distances D and d can be shortened, and a small optical module can be provided.

  According to the optical module of the third embodiment configured as described above, it can be configured by the three-core ferrule 15, the optical function element 7, the substrate 10, the other mounting case 10, and the like. Even when compared with the configuration, the reflection type optical module can be configured with a significantly smaller number of parts.

In the second and third embodiments described above, the demultiplexer that extracts the light of the wavelength (λ1 + λ2) input from the first optical path, the light of the wavelength λ1 from one of the two second optical paths, and the light of the wavelength λ2 from the other Although explained using, the present invention is not limited to this, and can also be used as a multiplexer.
For example, in the optical module shown in FIGS. 6 and 7, when light having the wavelength λ1 is incident from one of the two second optical paths and light having the wavelength λ2 is incident from the other, the light having the wavelength (λ1 + λ2) is extracted from the first optical path. be able to.

In the second and third embodiments, the optical module having 1 × 2 input / output ports has been described. However, it is also possible to configure the input or output ports by three or more.
In this case, for example, a multilayer substrate having three or more reflective filter films may be used as the optical function element 7. In this way, a multi-branch filter module can be configured.

  In the first to third embodiments described above, examples in which the ferrule having a through hole is used have been described. However, in the present invention, instead of the ferrule, for example, a substrate having a V groove instead of the through hole, or the like. The fiber holding member may be used.

As an example, an optical module (ferrule-type optical component) according to the present invention was actually prototyped and evaluated.
The optical module evaluated as a prototype is the 1 × 2 reflective optical module shown in FIG.

The fiber used in this example was manufactured as follows.
The GI fiber 1 has an outer diameter of 125 μm, a core diameter of 105 μm, and a Δ = 0.0027. One end thereof is fused and connected to a single mode fiber (optical fiber 3), and then cut at a pitch length P = 0.07 (Z = 0.31 mm / f = 1200 μm), and the other end is set to a refractive index n1 = 1. 48 coreless fibers were fused and cut at a coreless fiber length of 0.3 mm. Three such fusion spliced fibers were prepared and mounted in a three-core ferrule made of zirconia ceramic and fixed by adhesion. The three-core ferrule has a length of 8 mm, a width of 2 mm, and a height of 2 mm, and a core interval D = 184 μm and d = 130 μm.

  Thereafter, polishing was performed so that the end face angle θ was 20 °, and an AR coating for antireflection was applied to each of the fiber entrance and exit ends (end face of the coreless fiber). In this way, optical paths in which the fiber and the lens were integrated were respectively formed in the through holes of the ferrule 15.

  Ferrules 15 each having an optical path formed in each through hole were fixedly mounted on a zirconia substrate 10 having a length of 10 mm, a width of 2.5 mm, and a thickness of 1 mm with a thermosetting adhesive. The optical functional element 7 has a wavelength selection filter on both sides of a substrate having a refractive index n2 = 1.41, t = 0.5 mm, height 1 mm and width 2 mm made of BK7 glass, and a filter thin film 8 on the surface with a wavelength of 1300 nm. The light was reflected, and light having a wavelength of 1550 nm was reflected by the reflective thin film 9 on the bottom surface. It was fixedly installed with a thermosetting adhesive facing the three-core ferrule 15 at a distance of L = 0.5 mm. With this configuration, the incident angle β of the optical element 7 is about 10.5 ° and the refraction angle γ is about 7.5 °.

It was installed in a metal case 11 having a length of 12 mm, a width of 5 mm, and a height of 4 mm to constitute a reflection type optical module.
In the optical module configured as described above, when light of wavelength λ1 = 1320 nm and light of wavelength λ2 = 1554 nm are incident from port 1 (incident end of the first optical path), port 2 (of the two second optical paths) The light having the wavelength λ1 = 1320 nm from the output port of the second optical path closer to the first optical path of the first optical path, and the port 3 (the output port of the second optical path farther from the first optical path of the two second optical paths). Output light having a wavelength of λ2 = 1554 nm.

  At this time, the insertion loss from port 1 to port 2 was 0.46 dB, and the return loss was 53 dB. The insertion loss from port 1 to port 3 was 0.57 dB, and the return loss was 51 dB.

  As described above, with the optical module according to the present invention, the focal length can be adjusted by adjusting the length P of the GI fiber by integrating the fiber and the lens, and the optical distance can be adjusted by adjusting the angle Θ. It was shown that a reflective optical module that can be easily combined and can be made compact and integrated can be realized by multilayering the substrate of the element 7.

  Further, in the two-core reflection type optical module size in the case of Patent Document 1, the distance between the fibers is 8.1 mm, the length is 25 mm, the width is 15 mm, and the height is 5 mm. In the three-core optical module, for example, the distance between the fibers can be 184 μm and 130 μm, and the case in this case can have a length of 12 mm, a width of 2.5 mm, and a thickness of 4 mm, and can be reduced to 1/8 in volume. As a result, it is understood that the optical module according to the present invention enables the reflective optical module to be significantly reduced in size and integrated.

It is typical sectional drawing which shows the structure of the optical module of Embodiment 1 which concerns on this invention. 3 is a schematic cross-sectional view showing a configuration of one optical path in the optical module according to Embodiment 1. FIG. It is the image figure which showed the ray tracing with respect to the pitch P in GI fiber. It is the graph which showed the relationship between the pitch P of GI fiber with respect to (DELTA) value of GI fiber, and a focal distance. It is sectional drawing which shows the structure of GI fiber typically. It is sectional drawing which shows the structure of a reflection type optical isolator. It is typical sectional drawing which shows the structure of the optical module of Embodiment 2 which concerns on this invention. It is typical sectional drawing which shows the structure of the optical module of Embodiment 3 which concerns on this invention. It is a typical side view which shows the structure of the optical module of Embodiment 3 which concerns on this invention.

Explanation of symbols

1: GI fiber, 2: coreless fiber, 3: optical fiber, 4, 5, 6, 15: ferrule, 7: optical functional element, 10: substrate, 11: case.

Claims (10)

A ferrule having a front end face, a rear end face, and first and second through holes penetrating from the front end face to the rear end face, respectively;
The first optical fiber located on the rear end face side of the first through hole, the first coreless fiber located on the front end face side of the first through hole, and the first through hole in the first through hole. A first graded index fiber positioned between an optical fiber and the first coreless fiber, and collimating light emitted from the first optical fiber and entering the first coreless fiber; A first optical path,
The second optical fiber located on the rear end face side of the second through hole, the second coreless fiber located on the front end face side of the second through hole, and the second through hole in the second through hole. A second graded index fiber that is located between the optical fiber and the second coreless fiber and that collimates the light emitted from the second optical fiber and enters the second coreless fiber. A second optical path,
A reflective optical functional element that is incident on the second optical path after reflecting and / or transmitting light emitted from the first optical path based on the function;
An optical module.   The front end surface of the ferrule includes two first and second surfaces having different directions, the opening of the first through hole is on the first surface, and the opening of the second through hole is the The optical module according to claim 1, which is on the second surface.   3. The light according to claim 2, wherein an exit end face of the first coreless fiber and the first face are located on the same plane, and an entrance end face of the second coreless fiber and the second face are located on the same plane. module.   The direction of the exit end face and the first surface and the direction of the entrance end face and the second surface are based on the position of the incident portion of the reflective optical functional element and the distance between the reflective optical functional element and the ferrule. The optical module according to claim 3, which is set as described above.   There are a plurality of the second through holes, each of which constitutes the second optical path, and the reflective optical functional element reflects and / or transmits the light emitted from the first optical path based on its function. The optical module according to claim 1, wherein the optical module is incident on each of the plurality of second optical paths.   The reflective optical function element is one selected from the group consisting of an optical isolator element, a filter element, a Faraday rotator, a polarizer, a diffraction grating, and a total reflection mirror. The optical module described in one. The optical module according to claim 1, further comprising a holding member having a front end face, a rear end face, and first and second grooves penetrating from the front end face to the rear end face instead of the ferrule,
An optical module in which the first optical path is disposed in the first groove and the second optical path is disposed in the second groove.   The front end surface of the holding member includes two first and second surfaces having different directions, one end of the first groove is on the first surface, and one end of the second groove is the second surface. The optical module according to claim 7.   9. The optical module according to claim 8, wherein the exit end face of the first coreless fiber and the first face are located on the same plane, and the entrance end face of the second coreless fiber and the second face are located on the same plane. . It has a front end surface, a rear end surface, and first and second through holes penetrating from the front end surface to the rear end surface, respectively, and the front end surface of the ferrule has two first and second surfaces having different directions. A ferrule for an optical module including a surface, wherein the opening of the first through hole is on the first surface, and the opening of the second through hole is on the second surface.

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