JP4591964B2 - Optical fiber connection method - Google Patents

Description

  The present invention relates to a method for connecting optical fibers, particularly holey fibers.

  In recent years, holey fibers have attracted attention as optical fibers that enable characteristics that cannot be realized with conventional optical fibers such as large structural dispersion and low bending loss characteristics. A holey fiber is an optical fiber having a cladding 2 having a structure in which a plurality of axially continuous air holes 1 (holes) are regularly arranged as shown in FIGS. 1 (a) and 1 (b). It is. Further, it is sometimes called a photonic crystal fiber because it is understood that air holes are regularly arranged.

  In this specification, a holey assist fiber (having a hole 3 having a core 3 having a higher refractive index than that of the clad 2 and having an air hole 1 in the surrounding clad 2 is used. This is called HAF (Hole-Assisted Fiber) (FIG. 1 (a)), and does not have the above-mentioned refractive index distribution, but a large number of air holes 1 are regularly arranged in the clad 2, and the effective refractive index of the clad 2 The holey fiber having a refractive index difference from the core 3 (corresponding portion) is referred to as an air-clad fiber (FIG. 1B).

Conventionally, in order to connect these fibers, a fusion splicing technique as disclosed in Patent Document 1 or a mechanical splice technique has been used.
JP 2004-53625 A Japanese Patent No. 3444352 N. Hirose, et.al., "Optical Solder Effects of Self-Written Waveguides in Optical Circuit Devices Coupling", 2001 Electronic Components and Technology Conference, 2001, p.223-228

  However, in order to perform fusion splicing, it is necessary to perform arc discharge and melt the tip of the optical fiber at a high temperature. As a result, the air hole collapses in the vicinity of the connection point, so in the case of HAF, the vicinity of the connection point has a structure similar to that of a conventional fiber such as SMF. The neighborhood becomes homogeneous glass. As a result, the bending loss characteristics of HAF are deteriorated, and the air clad fiber has a performance deterioration such as an increase of connection loss due to the disappearance of the refractive index difference between the core portion and the cladding portion at the connection portion.

  In addition, when using a mechanical splice for connection, in general, in order to suppress loss and reflection at the connection point, a liquid refractive index matching having a refractive index almost equal to that of the core glass at the transmission wavelength between the connected fiber end faces. The agent was applied. As a result, in the holey fiber, the refractive index matching agent infiltrates into the fine air hole by capillary action, and the refractive index difference due to the air hole is lost at the connection portion, resulting in performance degradation similar to fusion splicing. . Furthermore, since the refractive index matching agent infiltrates into the air hole with time, problems such as environmental resistance and changes in characteristics over time have occurred with respect to loss and reflection characteristics at the connection point.

  Accordingly, there is an urgent need to establish a low loss and simple holey fiber connection technology that can solve these problems.

  In order to solve the above-described problems, the present invention is characterized by using a self-forming optical waveguide technique (see Patent Document 2) when connecting holey fibers.

  Specifically, holey fibers or holey fibers and other types of optical fibers (hereinafter referred to as different types of fibers) are arranged so that their one ends are substantially opposed to each other with a gap therebetween, and after curing, A mixed solution containing at least two types of photocurable resins each having a different refractive index and curing start wavelength is interposed between one end of each of the fibers, and a light source having at least two types of wavelengths is used. A core portion and a clad portion are formed by curing a photocurable resin, or a mixture containing at least two types of photocurable resins having different refractive indexes after curing and different curing times and the same curing start wavelength. A solution is interposed between one end of each of the fibers, and a light curable resin in the mixed solution is cured using a light source of at least one type of wavelength to form a core. And characterized by forming a cladding portion.

  In addition, the heterogeneous fiber refers to all optical fibers having a waveguide structure based on a difference in refractive index of materials, such as a single mode fiber (SMF), a multimode fiber (MMF), and a dispersion shifted fiber (DSF), and having no air holes. .

  According to the present invention, by connecting by self-forming optical waveguide technology, it becomes possible to easily connect holey fibers or holey fibers and dissimilar fibers, and by conventional fusion splicing or mechanical splice. The problem of characteristic deterioration that has occurred can be avoided.

  The first reason is that a region having no refractive index distribution caused by various factors in the conventional connection technology does not exist between the optical fiber end faces in the self-forming optical waveguide technology. In the self-forming optical waveguide technology, it is possible to separate the formation stage (connection stage) of the core and the clad, and there is a refractive index distribution between the end faces of the optical fibers to be connected by the two types of photo-curing resins cured. This is due to the formation of the waveguide.

  The second reason is that in the self-forming optical waveguide technology, it is easy to prevent the difference in refractive index from the core due to air holes from being lost at the connection portion.

The time required for the viscosity or curing of the photocurable resin, the refractive index after curing can relatively freely controlled over a wide range of values, for example, the time required for hardening the plurality of air holes of the holey fiber It is also possible to adjust the value required for the resin to infiltrate to a certain depth (however, the diameter of each air hole is uniform). In this case, the refractive index after curing is adjusted to the core of the optical fiber. If the refractive index is adjusted to a value lower than the refractive index of the material, the refractive index of the cladding near the connection increases compared to the initial state (the state before connection), but the difference in refractive index from the core is completely as in the conventional technology. Is not lost, and the increase in connection loss is suppressed. In addition, since the cured resin is maintained in a solid state, the loss and reflection characteristics at the connection point are kept stable compared with the liquid refractive index matching agent, and the connection point as occurs in the mechanical splice technology. It is possible to reduce the deterioration of characteristics over time related to loss and reflection characteristics.

<Embodiment 1>
FIGS. 2 to 4 show the first embodiment of the optical fiber connection method of the present invention, in which an example of connecting holey fibers using light sources of two types of wavelengths is shown. 1, 4-2 is a holey fiber, 5 is a mixed solution of a photocurable resin, 6 is a light source (d) for forming a core part, and 7 is a light source (e) for forming a clad part.

  The mixed solution 5 of the photocurable resin includes two types of photocurable resins whose refractive index and curing start wavelength after curing are adjusted, that is, the first photocurable resin for forming the core portion and the cladding portion forming It is a mixed solution with the second photocurable resin and is prepared in advance.

Here, the adjustment of the refractive index after curing may be any value before the curing, but the refractive index n1 after curing of the first photocurable resin and the curing of the second photocurable resin. The subsequent refractive index n2 is
n1> n2
It means to adjust to meet the condition of.

  Further, the adjustment of the curing start wavelength means that only the first curable resin starts the curing reaction by the light from the light source (d) 6 for forming the core part, and the light from the light source (e) 7 for forming the cladding part. It refers to selecting the wavelength of each resin and each light source so that only the second curable resin initiates the curing reaction by light.

  First, as shown in FIG. 2, the holey fibers 4-1 and 4-2 are arranged such that one end to be connected to each other is substantially opposed with a gap.

  As the detailed arrangement of each holey fiber at this time, there are two possible arrangements depending on whether the light source (d) 6 for forming the core part is connected to only one of the holey fibers or both.

  That is, when the light source (d) 6 for forming the core part is connected to only one of the holey fibers, it is necessary to arrange them so that their central axes coincide with each other with a gap (first arrangement). Also, when the core forming light source (d) 6 is connected to both holey fibers, the center axes are not necessarily aligned and the “photo soldering effect” in the self-forming waveguide technology (Non-Patent Document 1). (See 2), an operation is used that enables connection with low loss even when there is a certain degree of axial misalignment (second arrangement). However, in order to connect with lower loss, it is desirable to connect the light source (d) 6 for forming the core part to both holey fibers by arranging the respective center axes to coincide with each other.

  Each of the fibers 4-1 and 4-2 is held by holding means (not shown) such as a holding base having a V-groove and a holding plate for fixing the fiber to the base. It shall be maintained until the end. In addition, the relationship between the central axes of the fibers described above is only required to be maintained in the vicinity of one end to be connected, and it is needless to say that it is not necessary to have such a relationship in the entire length of each fiber. (This point is common to all the embodiments of the present invention).

  Next, the photocurable resin mixed solution 5 is interposed between the end faces of the holey fibers 4-1 and 4-2, and as shown in FIG. 3, either the holey fibers 4-1 or 4-2 or The core-forming light source (d) 6 connected to both the other ends is operated, and light having a wavelength for forming the core portion is incident from the other end. Then, light having a wavelength for forming the core portion is emitted from one or both ends of the holey fibers 4-1 and 4-2 into the mixed solution 5, whereby the first photocuring property in the mixed solution 5 is obtained. Only the resin reacts and cures, and a waveguide (core portion) 8 is formed between the end faces of the holey fibers 4-1 and 4-2.

  In addition, as a specific method of interposing the mixed solution 5 between the end faces of the fibers 4-1 and 4-2, for example, the fibers 4-1 and 4-2 of the support base constituting the holding means described above are used. What is necessary is just to provide the depression part for a liquid reservoir in the position where one end opposes, and the mixed solution 5 should just be dripped at this depression part.

  Next, after confirming that the core portion 8 is reliably formed between the end faces of the holey fiber, the light source (e) 7 for forming the cladding portion is operated as shown in FIG. The light having the wavelength for forming the cladding portion is irradiated to the already formed waveguide portion between the ends of 1,4-2. Then, only the second photocurable resin in the mixed solution 5 reacts and cures, and the cured portion becomes the clad portion 9 between the holey fibers.

  Through the above-described steps, the problem of deterioration of characteristics caused by the conventional fusion splicing or mechanical splice can be avoided by performing the connection by the self-forming optical waveguide technology.

  The first reason is that a region having no refractive index distribution caused by various factors in the conventional connection technology does not exist between the optical fiber end faces in the self-forming optical waveguide technology. In the self-forming optical waveguide technology, it is possible to separate the formation stage (connection stage) of the core and the clad, and there is a refractive index distribution between the end faces of the optical fibers to be connected by the two types of photo-curing resins cured. This is due to the formation of the waveguide.

  The second reason is that in the self-forming optical waveguide technology, it is easy to prevent the difference in refractive index from the core due to air holes from being lost at the connection portion.

The time required for the viscosity or curing of the photocurable resin, the refractive index after curing can relatively freely controlled over a wide range of values, for example, the time required for hardening the plurality of air holes of the holey fiber It is also possible to adjust the value required for the resin to infiltrate to a certain depth (however, the diameter of each air hole is made uniform). In this case, the refractive index after curing is adjusted to the core of the optical fiber. If the refractive index is adjusted to a value lower than the refractive index of the material, the refractive index of the cladding near the connection increases compared to the initial state (the state before connection), but the refractive index difference from the core is completely as in the conventional technology. Is not lost, and the increase in connection loss is suppressed. In addition, since the cured resin is maintained in a solid state, the loss and reflection characteristics at the connection point are kept stable compared to the liquid refractive index matching agent, and the connection point is similar to that caused by mechanical splicing technology. It is possible to reduce the deterioration of characteristics over time related to loss and reflection characteristics.

<Embodiment 2>
FIGS. 5 to 7 show an embodiment 2 of an optical fiber connection method of the present invention, in which an example of connecting a holey fiber and a different fiber using light sources of two types of wavelengths is shown. The same components as those in Embodiment 1 are denoted by the same reference numerals. That is, 4 is a holey fiber, 5 is a mixed solution of a photocurable resin, 6 is a light source (d) for forming a core part, 7 is a light source (e) for forming a clad part, and 10 is a dissimilar fiber.

  First, as shown in FIG. 5, the holey fiber 4 and the dissimilar fiber 10 are arranged so that one ends to be connected to each other are substantially opposed with a gap therebetween.

  As the detailed arrangement of each fiber at this time, as in the case of the first embodiment, the light source (d) 6 for forming the core part is connected to only one of the holey fiber or the different fiber, or the holey fiber and There are two possible arrangements depending on whether they are connected to both types of fibers.

  That is, when the core portion forming light source (d) 6 is connected to only one of the holey fiber and the different type of fiber, it is necessary to arrange them so that the respective central axes coincide with each other with a gap (first). Placement). In addition, when the core forming light source (d) 6 is connected to both the holey fiber and the dissimilar fiber, the central axes are not necessarily aligned and the “photo soldering effect” in the self-forming waveguide technology (non- According to Japanese Patent Application Laid-Open No. H10-260260, an effect that connection can be made with low loss even when there is a certain degree of misalignment is used (second arrangement). However, in order to connect with lower loss, even when the light source (d) 6 for forming the core part is connected to both the holey fiber and the dissimilar fiber, the respective central axes should be arranged so as to be connected. Is desirable.

  Next, the photocurable resin mixed solution 5 is interposed between the end faces of the holey fiber 4 and the different type fiber 10, and as shown in FIG. 6, the other end of one or both of the holey fiber 4 and the different type fiber 10 is used. The core-forming light source (d) 6 connected to is operated, and light having a wavelength for forming the core part is incident from the other end. Then, light having a wavelength for forming the core part is emitted into the mixed solution 5 from one or both ends of the holey fiber 4 and the dissimilar fiber 10, whereby only the first photocurable resin in the mixed solution 5 is emitted. Reacts and hardens, and a waveguide (core portion) 11 is formed between the end faces of the holey fiber 4 and the different fiber 10.

  Next, after confirming that the core portion 11 is securely formed between the end faces of the holey fiber 4 and the different fiber 10, the light source (e) 7 for forming the cladding portion is operated as shown in FIG. Then, light having a wavelength for forming the cladding portion is irradiated onto the already formed waveguide portion between the ends of the holey fiber 4 and the different fiber 10. Then, only the second photocurable resin in the mixed solution 5 reacts and cures, and the cured portion becomes the cladding portion 12 between the holey fiber and the dissimilar fiber.

  As described above, the same effect as in the first embodiment can be exhibited in the connection between the holey fiber and the different type fiber.

<Embodiment 3>
8 to 10 show a third embodiment of the optical fiber connection method of the present invention, in which an example in which holey fibers are connected using a light source of one type of wavelength is shown. The same components as those in the first embodiment are denoted by the same reference numerals. That is, 4-1 and 4-2 are holey fibers, 13 is a mixed solution of a photocurable resin, and 14 is a light source (f).

  The photo-curable resin mixed solution 13 includes two types of photo-curing resins in which the refractive index after curing and the time required for curing are adjusted, that is, the first photo-curing resin for forming the core portion and the clad portion-forming solution. It is a mixed solution with the second photo-curable resin, and is prepared in advance.

Here, the adjustment of the refractive index after curing may be any value before the curing, but the refractive index n1 after curing of the first photocurable resin and the curing of the second photocurable resin. The subsequent refractive index n2 is
n1> n2
It means to adjust to meet the condition of.

In addition, the adjustment of the time required for curing is the time t1 from the start of curing by starting light irradiation from the light source in the first curable resin to the end of curing and the light irradiation from the light source in the second curable resin. The time t2 from the start of curing to the end of curing is
t1 <t2
It means to adjust to meet the condition of.

  As the curing start wavelength, the wavelength of each resin and the light source is selected so that the curing reaction is started by the light from the light source (f) 14 in both the first and second photocurable resins.

  First, as shown in FIG. 8, the holey fibers 4-1 and 4-2 are arranged so that one ends to be connected to each other are substantially opposed to each other with a gap therebetween.

  As the detailed arrangement of each holey fiber at this time, as in the case of the first embodiment, there are two arrangements depending on whether the light source (f) 14 is connected to only one of the holey fibers or both. It is done.

  That is, when the light source (f) 14 is connected to only one of the holey fibers, the light source (f) 14 needs to be arranged so that the respective central axes coincide with each other with a gap (first arrangement). Further, when the light source (f) 14 is connected to both holey fibers, the central axes are not necessarily arranged so as to coincide with each other due to the “photo soldering effect” (see Non-Patent Document 1) in the self-forming waveguide technology. Even when there is an axial misalignment, an effect that connection can be made with low loss is used (second arrangement). However, in order to connect with a lower loss, it is desirable to connect the light sources (f) 14 to both holey fibers by arranging them so that their respective central axes coincide with each other.

  Next, the photocurable resin mixed solution 13 is interposed between the end faces of the holey fibers 4-1, 4-2, and as shown in FIG. 9, either one of the holey fibers 4-1, 4-2 or The light source (f) 14 connected to both other ends is operated, and light is incident from the other end. Then, light is emitted from one or both ends of the holey fibers 4-1 and 4-2 into the mixed solution 13, thereby reacting with the first and second photocurable resins in the mixed solution 13. However, the time required for curing is different between the first photocurable resin and the second photocurable resin in the mixed solution 13, and the time t1 required for curing the first photocurable resin is longer. Since the time required for curing the second photo-curing resin is shorter than t2, the first photo-curing resin reacts and cures more and is guided between the end faces of the holey fibers 4-1 and 4-2. A waveguide (core part) 15 is formed.

  Next, after confirming that the core portion 15 is reliably formed between the end faces of the holey fiber, the light source (f) 14 not connected to the fiber is operated as shown in FIG. The light is applied to the already formed waveguide portion between the ends of -1,4-2. Then, similarly to the above, the first and second photocurable resins in the mixed solution 13 react and cure, and the cured portion becomes the clad portion 16 between the holey fibers. As a result, the molar concentration of the first photocurable resin is low, resulting in a difference in refractive index between the core portion 15 and the first photocurable resin.

  In order to obtain the optimum refractive index difference for the waveguide conditions, the molar concentration of the first photocurable resin for forming the core portion remaining in the mixed solution 13 at the end of the formation of the core portion 15 was considered. It is necessary to adjust the refractive index after curing of the second photocurable resin for forming the clad portion.

  As described above, the same effects as those of the first embodiment can be exhibited even in the connection between holey fibers using light sources of one type of wavelength.

<Embodiment 4>
FIGS. 11 to 13 show an optical fiber connection method according to a fourth embodiment of the present invention, here an example in which a holey fiber and a dissimilar fiber are connected using a light source of one type of wavelength. The same components as those in the second and third embodiments are denoted by the same reference numerals. That is, 4 is a holey fiber, 10 is a different fiber, 13 is a mixed solution of a photocurable resin, and 14 is a light source (f).

  First, as shown in FIG. 11, the holey fiber 4 and the heterogeneous fiber 10 are arranged so that one ends to be connected to each other are substantially opposed to each other with a gap therebetween.

  As the detailed arrangement of each fiber at this time, as in the case of the third embodiment, the light source (f) 14 is connected to only one of the holey fiber or the different fiber, or both the holey fiber and the different fiber are connected. There are two possible arrangements depending on whether they are connected.

  That is, when the light source (f) 14 is connected to only one of the holey fiber and the different type fiber, it is necessary to arrange them so that their central axes coincide with each other with a gap (first arrangement). Further, when the light source (f) 14 is connected to both the holey fiber and the dissimilar fiber, the center axes are not necessarily arranged to coincide with each other, and the “photo soldering effect” in the self-forming waveguide technology (see Non-Patent Document 1). Therefore, even when there is a certain degree of axial misalignment, the effect of enabling connection with low loss is used (second arrangement). However, in order to connect with lower loss, even when the light source (f) 14 is connected to both the holey fiber and the dissimilar fiber, it is desirable that the respective central axes be arranged so as to be connected.

  Next, the mixed solution 13 of the photocurable resin is interposed between the end faces of the holey fiber 4 and the different fiber 10, and as shown in FIG. 12, either one of the holey fiber 4 and the different fiber 10 or the other end of both. The light source (f) 14 connected to is operated, and light enters from the other end. Then, light is emitted from one or both ends of the holey fiber 4 and the dissimilar fiber 10 into the mixed solution 13, thereby reacting with the first and second photocurable resins in the mixed solution 13 and curing. However, the time required for curing differs between the first photocurable resin and the second photocurable resin in the mixed solution 13, and the time t1 required for curing the first photocurable resin is the first. 2 is shorter than the time t2 required for curing the photo-curing resin, the first photo-curing resin is more reacted and cured, and a waveguide (core portion) is formed between the end faces of the holey fiber 4 and the dissimilar fiber 10. ) 17 is formed.

  Next, after confirming that the core portion 17 is reliably formed between the end faces of the holey fiber and the different fiber, as shown in FIG. 13, the light source (f) 14 not connected to the fiber is operated, Light is irradiated to the already formed waveguide portion between the ends of the holey fiber 4 and the different fiber 10. Then, similarly to the above, the first and second photocurable resins in the mixed solution 13 are also reacted and cured, and the cured portion becomes the clad portion 18 between the holey fiber and the dissimilar fiber. Since the molar concentration of the first photocurable resin is reduced by the formation of 17, as a result, a refractive index difference is generated between the core portion 17.

  In order to obtain the optimum refractive index difference for the waveguide conditions, the molar concentration of the first photocurable resin for forming the core portion remaining in the mixed solution 13 at the end of the formation of the core portion 17 was considered. It is necessary to adjust the refractive index after curing of the second photocurable resin for forming the clad portion.

  As described above, the same effect as that of the first embodiment can be exhibited in the connection between the holey fiber and the dissimilar fiber using one kind of light source.

Cross section of holey fiber The block diagram which shows Embodiment 1 of the connection method of the optical fiber of this invention Manufacturing process diagram showing Embodiment 1 of the optical fiber connecting method of the present invention Manufacturing process diagram showing Embodiment 1 of the optical fiber connecting method of the present invention The block diagram which shows Embodiment 2 of the connection method of the optical fiber of this invention Manufacturing process diagram showing Embodiment 2 of the optical fiber connecting method of the present invention Manufacturing process diagram showing Embodiment 2 of the optical fiber connecting method of the present invention The block diagram which shows Embodiment 3 of the connection method of the optical fiber of this invention Manufacturing process diagram showing Embodiment 3 of the optical fiber connecting method of the present invention Manufacturing process diagram showing Embodiment 3 of the optical fiber connecting method of the present invention The block diagram which shows Embodiment 4 of the connection method of the optical fiber of this invention Manufacturing process diagram showing Embodiment 4 of the optical fiber connecting method of the present invention Manufacturing process diagram showing Embodiment 4 of the optical fiber connecting method of the present invention

Explanation of symbols

  1: air hole, 2: clad, 3: core, 4,4-1, 4-2: holey fiber, 5, 13: mixed solution of photocurable resin, 6: light source (d) for forming core part, 7: light source (e) for forming a cladding part, 8, 11, 15, 17: core part (waveguide), 9, 12, 16, 18: cladding part, 10: dissimilar fiber, 14: light source (f).

Claims (4)

A method for connecting holey fibers,
Place the holey fibers so that each one end faces each other with a gap between them,
Interposing a mixed solution containing at least two types of photocurable resins having different refractive indices and curing start wavelengths after curing, between one end of each of the fibers,
In the optical fiber connection method of forming the core part and the clad part by curing the photocurable resin in the mixed solution using a light source of at least two types of wavelengths,
And sets a value required for infiltration to a certain depth before Kisukuna without even two in the plurality of air holes in both the photocurable resin holey fiber the time required for curing of the photocurable resin,
An optical fiber connecting method, wherein the refractive index after curing of the at least two kinds of photocurable resins is set to a value lower than the refractive index of the core of the holey fiber. A method of connecting a holey fiber and a dissimilar fiber,
The holey fiber and the dissimilar fiber are arranged so that one end of each is substantially opposed with a gap between them,
Interposing a mixed solution containing at least two types of photocurable resins having different refractive indices and curing start wavelengths after curing, between one end of each of the fibers,
In the optical fiber connection method of forming the core part and the clad part by curing the photocurable resin in the mixed solution using a light source of at least two types of wavelengths,
And sets a value required for infiltration to a certain depth before Kisukuna without even two in the plurality of air holes in both the photocurable resin holey fiber the time required for curing of the photocurable resin,
An optical fiber connecting method, wherein the refractive index after curing of the at least two kinds of photocurable resins is set to a value lower than the refractive index of the core of the holey fiber. A method for connecting holey fibers,
Place the holey fibers so that each one end faces each other with a gap between them,
A mixed solution containing at least two types of photocurable resins having different refractive indexes after curing and time required for curing and having the same curing start wavelength is interposed between one end of each fiber,
In the optical fiber connection method of forming the core part and the clad part by curing the photocurable resin in the mixed solution using a light source of at least one wavelength,
And sets a value required for infiltration to a certain depth before Kisukuna without even two in the plurality of air holes in both the photocurable resin holey fiber the time required for curing of the photocurable resin,
An optical fiber connecting method, wherein the refractive index after curing of the at least two kinds of photocurable resins is set to a value lower than the refractive index of the core of the holey fiber. A method of connecting a holey fiber and a dissimilar fiber,
The holey fiber and the dissimilar fiber are arranged so that one end of each is substantially opposed with a gap between them,
A mixed solution containing at least two types of photocurable resins having different refractive indexes after curing and time required for curing and having the same curing start wavelength is interposed between one end of each fiber,
In the optical fiber connection method of forming the core part and the clad part by curing the photocurable resin in the mixed solution using a light source of at least one wavelength,
And sets a value required for infiltration to a certain depth before Kisukuna without even two in the plurality of air holes in both the photocurable resin holey fiber the time required for curing of the photocurable resin,
An optical fiber connecting method, wherein the refractive index after curing of the at least two kinds of photocurable resins is set to a value lower than the refractive index of the core of the holey fiber.

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