JP2007121503A - Method for splicing optical fibers - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply splice PBGFs (Photonic Band Gap Fibers) to each other, or simply splice a PBGF and a full reflection waveguide type fiber together without producing degradation in characteristics and increase in connection loss. <P>SOLUTION: Between each one end of the PBGF 4-1, 4-2 to be spliced together, a mixed solution 5 of a first photo setting resin of which the refractive index after setting and the setting start wavelength are adjusted to a first refractive index n1 and a wavelength of a light source for forming a core part, respectively, and a second photo setting resin adjusted to a second refractive index n2 lower than the first refractive index n1 and the wavelength of the light source for forming a clad part, respectively, is interposed, to form the core part 8 by making the light of the wavelength for forming the core part incident to the other ends of the PBGF 4-1, 4-2 from the light source 6 and to form the clad part by radiating the light of the wavelength for forming the clad part from the light source 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for connecting an optical fiber, particularly a photonic bandgap fiber.

  In recent years, it is possible to guide a stronger peak power than a conventional optical fiber (hereinafter referred to as a total reflection waveguide type fiber) that consists of a core and a clad and guides light by total reflection. A photonic bandgap fiber (hereinafter referred to as PBGF) having various characteristics such as a material loss that can be reduced to the limit and a small nonlinear optical effect has attracted attention (Non-Patent Document 1). reference).

  As shown in FIG. 1, PBGF is a system in which a plurality of axially continuous air holes 1 (holes) are regularly arranged, and the effective refractive index of the cladding part 3 is higher than the refractive index of the core part 2. It is an optical fiber having the structure. In particular, in the PBGF structure shown in FIG. 1A, the air holes 1 are arranged in a hexagonal shape, and there is one air hole at the center, which is also called a honeycomb structure. Further, the structure of PBGF shown in FIG. 1B is called a hollow core structure in view of a huge hollow portion at the center.

Conventional optical fibers are generally made of silica-based glass or the like, and a dopant material is added to the core or the clad to give a refractive index difference therebetween. As a result, light is totally reflected at the boundary between the high refractive index core and the low refractive index cladding, and the light is guided in the core. On the other hand, in PBGF, light is guided not by total reflection due to a difference in refractive index but by a photonic band gap due to a periodic structure of air holes.
Japanese Patent No. 3444352 Takenaga et al. "Prototype of photonic bandgap fiber", Proceedings of the 2005 IEICE General Conference, C-3-66, March 2005, p. 236 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

  Conventionally, optical fiber connection methods include fusion splicing technology or mechanical splicing technology, but it has been difficult to connect PBGF with low loss and simpleness.

  The reason for this is that in fusion splicing, it is necessary to perform arc discharge and melt the tip of the optical fiber at high temperature. However, the discharge disturbs the periodic structure of the air hole around the splicing point and causes a refractive index difference. This is because, in addition to the generation of connection loss, excessive loss due to disturbance near the connection point of the photonic band gap structure occurs.

  In mechanical splices, a liquid refractive index matching agent is generally applied between the fiber end faces to be connected in order to suppress loss and reflection at the connection point. This refractive index matching agent is applied to the air hole by capillary action. This is because the infiltration causes an excessive loss due to disturbance near the connection point of the photonic band gap structure as in the fusion splicing.

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

  In order to solve the above-mentioned problems, the present invention is characterized in that a self-forming optical waveguide technique (see Patent Document 1) is used when connecting PBGFs.

  Specifically, PBGFs or PBGFs and total reflection waveguide type fibers are arranged so that their one ends are substantially opposed to each other with a gap therebetween, and at least two types of refractive indexes after curing and curing start wavelengths are different from each other. The mixed solution containing the photocurable resin is interposed between the one ends of the fibers, and the core portion and the clad are cured by curing the photocurable resin in the mixed solution using light sources of at least two types of wavelengths. A mixed solution containing at least two types of photo-curing resins having different refractive indexes after curing and different times required for curing and having the same curing start wavelength between the ends of the fibers. The core portion and the clad portion are formed by interposing and curing the photocurable resin in the mixed solution using a light source having at least one wavelength.

  It should be noted that the total reflection waveguide type fiber is precisely a single mode fiber (SMF), a multimode fiber (MMF), a dispersion shifted fiber (DSF), a holey fiber, etc. It refers to all optical fibers having a structure / principle that guides light.

  According to the present invention, it is possible to easily connect between PBGFs or between a PBGF and a total reflection waveguide fiber by performing connection using a self-forming optical waveguide technique, and to perform conventional fusion splicing or mechanical connection. It is possible to avoid the problem of characteristic deterioration that has occurred due to splicing.

  The reason is that, in the self-forming optical waveguide technology, the viscosity of the photocurable resin, the time required for curing, and the refractive index after curing can be controlled relatively freely within a wide range of values. Reduces the time required for curing, reduces the infiltration of the resin into a plurality of PBGF air holes by capillary action, or restricts the depth of infiltration to a certain extent, in other words, the resin has a capillary action To set (adjust) a value that does not fill the plurality of air holes of PBGF, or adjust the time required for curing to a value shorter than the time required for the resin to infiltrate into the plurality of air holes of PBGF by capillary action. Or the viscosity is adjusted to a value that allows the resin to infiltrate into a plurality of PBGF air holes to a certain depth by capillary action, or required for curing. By adjusting the time required for the resin to infiltrate into a plurality of PBGF air holes to a certain depth by capillary action (however, the diameter of each air hole is uniform). It can be kept in a state that does not affect the nick band gap structure. Therefore, it is possible to reduce loss and performance degradation due to changes in the waveguide structure when connected using the conventional connection method.

  In addition, if the refractive index after curing of the photocurable resin for forming the core portion is set to a value higher than the refractive index after curing of the photocurable resin for forming the clad portion, it was formed between the ends. Light can be guided by total reflection in a waveguide, that is, a self-forming optical waveguide, and can be connected with a lower loss than in the case of connection using a conventional connection method.

<Embodiment 1>
FIGS. 2 to 4 show an embodiment of the optical fiber connection method of the present invention, in this case an example in which PBGFs are connected using light sources of two types of wavelengths. , 4-2 is PBGF, 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 photo-curable resin mixed solution 5 includes two types of photo-curable resins whose refractive index and curing start wavelength after curing are adjusted, that is, a first photo-curable resin for forming a core (for example, a radical curable resin). ) And a second photo-curing resin (for example, cation-curing epoxy resin) for forming the clad portion, and 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 PBGFs 4-1 and 4-2 are arranged so that one ends to be connected are substantially opposed to each other with a gap therebetween.

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

  That is, when the light source (d) 6 for forming the core part is connected to only one of the PBGFs, it is necessary to arrange the respective central axes so as to coincide with each other with a gap (first arrangement). Further, when the core forming light source (d) 6 is connected to both of the PBGFs, the center axis is not necessarily aligned, and the “photo soldering effect” in the self-forming waveguide technology (see Non-Patent Document 2). ) Is used (second arrangement) in which connection is possible with low loss even when there is a certain degree of axial misalignment. However, in order to connect with a lower loss, it is desirable to connect the light sources (d) 6 for forming the core part to both PBGFs by arranging the respective center axes to coincide with each other.

  Each PBGF 4-1 and 4-2 are held by a holding means (not shown), for example, a holding base comprising a support base having a V-groove and a pressing plate for fixing the fiber to this base. It shall be maintained until time. 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 mixed solution 5 of the photocurable resin is interposed between the end faces of the PBGF 4-1 and 4-2, and as shown in FIG. 3, one or both of the other ends of the PBGF 4-1 and 4-2. 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, the light of the wavelength for core part formation is radiate | emitted in the mixed solution 5 from the end of either or both of PBGF4-1 and 4-2, and only 1st photocurable resin in the mixed solution 5 by this is emitted. Reacts and hardens, and a waveguide (core part) 8 is formed between the end faces of the PBGFs 4-1 and 4-2.

  In addition, as a specific method of interposing the mixed solution 5 between the end faces of each PBGF 4-1 and 4-2, for example, one end of each PBGF 4-1 and 4-2 of the support base constituting the holding means described above is used. It is only necessary to provide a depression for storing the liquid at a position opposite to the liquid and drop the mixed solution 5 on the depression.

  Next, after confirming that the core part 8 is reliably formed between the end faces of the PBGF, as shown in FIG. 4, the light source (e) 7 for forming the clad part is operated, and the PBGFs 4-1 and 4 are operated. -2 is irradiated with light having a wavelength for forming the clad portion on the already formed waveguide portion between the ends of -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 PBGFs.

  Here, in the self-forming optical waveguide technology, the viscosity of the photocurable resin, the time required for curing, and the refractive index after curing can be controlled relatively freely within a wide range of values. To set (adjust) a value that does not fill the plurality of air holes of PBGF, or adjust the time required for curing to a value shorter than the time required for the resin to infiltrate into the plurality of air holes of PBGF by capillary action. Or the viscosity is adjusted to a value that allows the resin to infiltrate into a plurality of PBGF air holes to a certain depth by capillary action, or the time required for curing is increased in the PBGF air holes by capillary action. By adjusting to the value required to infiltrate to a certain depth (however, the diameter of each air hole should be uniform). It can be kept in a state that does not affect the photonic band gap structure.

  Further, as described above, the refractive index n1 after curing of the first photocurable resin for forming the core portion is higher than the refractive index n2 after curing of the second photocurable resin for forming the cladding portion. Therefore, light can be guided by total reflection in a solid waveguide formed between one ends of the PBGF, that is, a self-forming optical waveguide. That is, the portion where the air hole of PBGF is kept uniform is guided by the photonic band gap, and the portion where the waveguide is formed by the photocurable resin is guided by total reflection. Conversion is performed. Thereby, it can connect with a low loss compared with the case where it connects using the conventional connection method.

  As described above, it is possible to easily connect with low loss by using the self-forming optical waveguide technology in connection between PBGFs, which is difficult to connect with low loss by the conventional connection method.

<Embodiment 2>
FIGS. 5 to 7 show an embodiment of the optical fiber connection method of the present invention, in this case, an example in which PBGF and a total reflection waveguide fiber are connected using light sources of two types of wavelengths. In the figure, the same components as those of the first embodiment are denoted by the same reference numerals. That is, 4 is PBGF, 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 cladding part, and 10 is a total reflection waveguide fiber. .

  First, as shown in FIG. 5, the PBGF 4 and the total reflection waveguide 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 a 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 PBGF or the total reflection waveguide fiber, Two arrangements are conceivable depending on whether to connect to both the PBGF and the total reflection waveguide type fiber.

  That is, when the core portion forming light source (d) 6 is connected to only one of the PBGF and the total reflection waveguide 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 core portion-forming light source (d) 6 is connected to both the PBGF and the total reflection waveguide type fiber, the central axes are not necessarily arranged to coincide with each other. ”(See Non-Patent Document 2), an effect 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, even when the light source (d) 6 for forming the core part is connected to both the PBGF and the total reflection waveguide type fiber, the respective central axes are arranged so as to coincide with each other. It is desirable to do.

  Next, the mixed solution 5 of the photocurable resin is interposed between the end faces of the PBGF 4 and the total reflection waveguide fiber 10, and as shown in FIG. 6, either the PBGF 4 or the total reflection waveguide fiber 10 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 of the PBGF 4 and the total reflection waveguide fiber 10 into the mixed solution 5, whereby the first photocuring property in the mixed solution 5 is emitted. Only the resin reacts and cures, and a waveguide (core portion) 11 is formed between the end faces of the PBGF 4 and the total reflection waveguide fiber 10.

  Next, after confirming that the core portion 11 is reliably formed between the end faces of the PBGF 4 and the total reflection waveguide fiber 10, as shown in FIG. 7, a light source (e) 7 for forming the cladding portion is provided. Operate and irradiate light having a wavelength for forming a cladding portion to the already formed waveguide portion between one end of the PBGF 4 and the total reflection waveguide fiber 10. Then, only the second photocurable resin in the mixed solution 5 reacts and cures, and the cured portion becomes the clad portion 12 between the PBGF and the total reflection waveguide fiber.

  As described above, the same effect as in the first embodiment can be exhibited in the connection between the PBGF and the total reflection waveguide fiber.

<Embodiment 3>
8 to 10 show an embodiment 3 of an optical fiber connecting method according to the present invention, in which an example in which PBGFs are connected using a light source of one type of wavelength is shown. The same components as 1 are denoted by the same reference numerals. That is, 4-1 and 4-2 are PBGF, 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 PBGFs 4-1 and 4-2 are arranged such that one ends to be connected are substantially opposed to each other with a gap.

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

  That is, when the light source (f) 14 is connected to only one of the PBGFs, it is necessary to arrange them so that their central axes coincide with each other with a gap (first arrangement). In addition, when the light source (f) 14 is connected to both PBGFs, the central axes are not necessarily arranged so that the “photo soldering effect” (see Non-Patent Document 2) in the self-forming waveguide technology is used to some extent. Even in the case where there is an axis deviation, an effect that connection can be made with low loss is used (second arrangement). However, in order to connect with lower loss, it is desirable to connect the light sources (f) 14 to both PBGFs by arranging the respective central axes to coincide with each other.

  Next, the mixed solution 13 of the photocurable resin is interposed between the end faces of the PBGF 4-1 and 4-2, and as shown in FIG. 9, one or both of the other ends of the PBGF 4-1 and 4-2. 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 PBGF 4-1 and 4-2 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 photocurable resin, the first photocurable resin reacts more and cures, and a waveguide (core portion) is formed between the end faces of the PBGFs 4-1 and 4-2. ) 15 is formed.

  Next, after confirming that the core portion 15 is reliably formed between the end faces of the PBGF, as shown in FIG. 10, the light source (f) 14 not connected to the fiber is operated, and the PBGF4-1, Light is irradiated to the already formed waveguide portion between the ends of 4-2. Then, similarly to the above, the first and second photocurable resins in the mixed solution 13 also react and cure, and the cured portion becomes the clad portion 16 between the PBGFs. Since the molar concentration of the first photocurable resin is low, a refractive index difference is generated between the core portion 15 as a result.

  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 effect as in the first embodiment can be exhibited even in the connection between PBGFs using light sources of one type of wavelength.

<Embodiment 4>
FIGS. 11 to 13 show an embodiment of the optical fiber connection method of the present invention, in this case, an example in which PBGF and a total reflection waveguide fiber are connected using a light source of one type of wavelength. In the figure, the same components as those in the second and third embodiments are denoted by the same reference numerals. That is, 4 is a PBGF, 10 is a total reflection waveguide fiber, 13 is a mixed solution of a photocurable resin, and 14 is a light source (f).

  First, as shown in FIG. 11, the PBGF 4 and the total reflection waveguide 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 PBGF and the total reflection waveguide type fiber, or the PBGF and the total reflection guide. Two arrangements can be considered depending on whether both are connected to the wave-type fiber.

  That is, when the light source (f) 14 is connected to only one of the PBGF and the total reflection waveguide type fiber, it is necessary to arrange them 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 the PBGF and the total reflection waveguide type fiber, the center axis is not necessarily aligned, and the “photo solder effect” in the self-forming waveguide technology (non-patent document) 2), an operation is used in which connection is possible with low loss even when there is a certain degree of axial misalignment (second arrangement). However, in order to connect with lower loss, even when the light source (f) 14 is connected to both the PBGF and the total reflection waveguide type 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 PBGF 4 and the total reflection waveguide fiber 10, and as shown in FIG. 12, either the PBGF 4 or the total reflection waveguide fiber 10 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 PBGF 4 and the total reflection waveguide fiber 10 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 PBGF 4 and the end faces of the total reflection waveguide fiber 10. A waveguide (core portion) 17 is formed.

  Next, after confirming that the core portion 17 is reliably formed between the end faces of the PBGF and the total reflection waveguide fiber, as shown in FIG. 13, the light source (f) 14 not connected to the fiber is connected. Operate and irradiate light to the already formed waveguide portion between the PBGF 4 and one end of the total reflection waveguide fiber 10. 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 18 between the PBGF and the total reflection waveguide fiber. Since the molar concentration of the first photocurable resin is low due to the formation of the core portion 17, a refractive index difference is generated between the core portion 17 and 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 PBGF and the total reflection waveguide fiber using one kind of light source.

Cross section of PBGF 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: Core part, 3: Cladding part, 4,4-1, 4-2: Photonic band gap fiber (PBGF), 5,13: Mixed solution of photocurable resin, 6: Core part Light source (d) for forming, 7: Light source (e) for forming the clad part, 8, 11, 15, 17: Core part (waveguide), 9, 12, 16, 18: Clad part, 10: Total reflection Waveguide fiber, 14: light source (f).

Claims (7)

A method of connecting photonic bandgap fibers,
Place the photonic bandgap fibers so that one end of each of them is facing 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,
A method of connecting optical fibers, comprising: forming a core part and a clad part by curing a photocurable resin in the mixed solution using light sources of at least two types of wavelengths. A method of connecting a photonic bandgap fiber and a total reflection waveguide fiber,
The photonic bandgap fiber and the total reflection waveguide fiber are arranged so that one ends of the photonic bandgap fiber and the total reflection waveguide fiber are opposed to each other with a gap therebetween,
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,
A method of connecting optical fibers, comprising: forming a core part and a clad part by curing a photocurable resin in the mixed solution using light sources of at least two types of wavelengths. A method of connecting photonic bandgap fibers,
Place the photonic bandgap fibers so that one end of each of them is facing 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,
A method of connecting optical fibers, comprising: forming a core portion and a cladding portion by curing a photocurable resin in the mixed solution using a light source having at least one wavelength. A method of connecting a photonic bandgap fiber and a total reflection waveguide fiber,
The photonic bandgap fiber and the total reflection waveguide fiber are arranged so that one ends of the photonic bandgap fiber and the total reflection waveguide fiber are opposed to each other with a gap therebetween,
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,
A method of connecting optical fibers, comprising: forming a core portion and a cladding portion by curing a photocurable resin in the mixed solution using a light source having at least one wavelength. In the optical fiber connection method according to any one of claims 1 to 4,
The viscosity of at least two types of photocurable resins is set to a value at which the photocurable resin is not filled in the plurality of air holes of the photonic bandgap fiber, or required for curing at least two types of photocurable resins. An optical fiber connection method characterized in that the time is set to a value shorter than the time required for the photo-curable resin to infiltrate into a plurality of air holes of the photonic band gap fiber. In the optical fiber connection method according to any one of claims 1 to 4,
The viscosity of at least two types of photocurable resins is set to a value at which the photocurable resin infiltrates into a plurality of air holes of the photonic band gap fiber to a certain depth, or at least two types of photocurable resins. A method of connecting an optical fiber, characterized in that the time required for curing is set to a value required for the photocurable resin to infiltrate into a plurality of air holes of the photonic band gap fiber to a certain depth. In the connection method of the optical fiber in any one of Claims 1 thru | or 6,
A method of connecting optical fibers, wherein the refractive index after curing of the photocurable resin for forming the core portion is set to a value higher than the refractive index after curing of the photocurable resin for forming the cladding portion.

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