JP5485355B2 - Optical waveguide component and method for manufacturing optical waveguide component - Google Patents

Description

  The present invention relates to an optical waveguide component and a method for manufacturing the optical waveguide component, and more particularly, to an optical waveguide component capable of changing the waveguide direction of light and a method for manufacturing the optical waveguide component.

  At present, the operation speed of an electric circuit is approaching that of an optical transmission circuit. Therefore, in order to compensate a part of the high-speed operation of the electric circuit with an optical waveguide, the electric circuit and the optical transmission line are fused. ing. An optical fiber is used as an example of the optical waveguide.

  Specifically, a VCSEL (Vertical Cavity Surface Emitting Laser) is mounted on an electric circuit board, an optical signal emitted from the VCSEL is incident on an optical waveguide, propagated, and mounted on a PD (photograph) mounted on the electric circuit board. The light is received by a diode) and transmitted.

The optical waveguide embedded in the electric circuit board guides light in a direction parallel to the electric circuit board. Therefore, in order to couple the laser light of the VCSEL to these optical waveguides, the optical waveguide of 90 degrees is used. A change of direction is required.
As such a 90-degree optical waveguide direction conversion method, the end face of the optical fiber is polished at 45 degrees, and metal polishing is applied to the polished surface to form a mirror, and the 90-degree optical waveguide direction conversion is performed, A method of converting the direction of the optical waveguide with a mirror having an angle of 45 degrees has been studied.

  Therefore, as a method of performing the 90-degree optical waveguide direction conversion, an optical waveguide in which a desired portion is bent in a curved shape with a predetermined bending radius has been proposed (for example, see Patent Document 1).

JP 2005-292718 A

  However, the optical waveguide proposed by the present inventors described in Patent Document 1 was able to form a small bent portion, but by adopting a small and simple structure, only a single mode optical waveguide was adopted. In addition, even for a multi-mode optical waveguide having a large diameter, it is desired that the light guiding direction can be reliably changed by the bent portion.

  Therefore, in order to solve the above-described problems, the present invention has a small number of parts, does not require alignment, and is not only a single-mode optical waveguide but also a large-diameter multimode optical waveguide with a small bent portion bent at a desired radius. Even if it exists, it aims at providing the manufacturing method of the optical waveguide which can change the waveguide direction of light, optical waveguide components, and an optical waveguide.

  In order to solve the above problems, an optical waveguide component according to the present invention accommodates an optical waveguide having a bent portion in which a target portion is bent in a curved shape with a predetermined bending radius, and at least the bent portion of the optical waveguide. A multi-mode optical fiber having a core and a clad covering the core, wherein a cross-sectional area ratio of the core and the clad in the bent portion is 1/5 or more, The bending portion has a diameter of 50 μm or more, and the fixing member has a fixing portion that directly fixes both sides of the bending portion of the optical waveguide, and a space portion that houses the bending portion, The refractive index matching agent having a refractive index smaller than the refractive index of the surface portion of the bent portion is filled.

  In the optical waveguide component of the present invention, preferably, the fixing member has an opening at an end surface in the direction of the bending center of the bent portion of the optical waveguide, and the refractive index matching agent can be filled from the opening. It is characterized by that.

  The optical waveguide component of the present invention is preferably characterized in that the outer diameter of the bent portion of the optical waveguide is smaller than the outer diameter of the linear portion.

  The optical waveguide component of the present invention is preferably characterized in that the outer diameter of the core of the bent portion is 30 μm or more.

  The optical waveguide component of the present invention is preferably characterized in that the bent portion has a diameter of 125 μm or less.

  The optical waveguide component of the present invention is preferably characterized in that the bending radius of the bent portion of the optical waveguide is 5.0 mm or less.

  The optical waveguide component of the present invention is preferably characterized in that a plurality of the optical waveguides are arranged.

  The optical waveguide component of the present invention is preferably characterized in that the refractive index matching agent is an ultraviolet curable resin.

The optical waveguide component of the present invention is preferably characterized in that the refractive index matching agent is a thermosetting resin.

The method of manufacturing an optical waveguide component of the present invention includes heating a heating target portion of the optical waveguide, bending the heating target portion into a curved shape with a predetermined bending radius, and forming a bent portion;
A fixing portion for directly fixing both sides of the bent portion of the optical waveguide; a step of storing the optical waveguide in a fixing member having a space portion for storing the bent portion; and a surface portion of the bent portion in the space portion. Filling a refractive index matching agent having a refractive index smaller than the refractive index, wherein the optical waveguide is a multimode optical fiber having a core and a clad covering the core, and the core of the bent portion A cross-sectional area ratio of the clad is 1/5 or more, and a diameter of the bent portion is 50 μm or more.

  The method for manufacturing an optical waveguide component of the present invention preferably includes a step of making the outer diameter of the bent portion of the optical waveguide smaller than the outer diameter of the linear portion before the optical waveguide is housed in the fixing member. It is characterized by.

  In the method of manufacturing an optical waveguide component according to the present invention, preferably, the step of reducing the outer diameter of the bent portion of the optical waveguide is a step of melting the clad of the bent portion with hydrofluoric acid.

  According to the optical waveguide component and the optical waveguide manufacturing method of the present invention, the number of components is small, alignment is unnecessary, and even a multi-mode optical waveguide having a large diameter with a small bent portion bent at a desired radius can be used. The waveguide direction can be changed, and the optical waveguide component can be downsized.

1 is a perspective view showing a first preferred embodiment of an optical waveguide of the present invention. It is a figure which shows the example of a shape of the optical waveguide which has a bending part. It is a perspective view which shows 1st Embodiment and 2nd Embodiment of the optical waveguide component of this invention. It is a figure which shows the state which remove | excluded the optical waveguide and the guide pin from the fixing member of the optical waveguide component of FIG. FIG. 5 is a cross-sectional view taken along line GG of the optical waveguide component in FIG. 4. It is a figure which shows the state which has arrange | positioned the substance for filling in the space part of the optical waveguide component shown in FIG. It is a figure which shows the example of refractive index distribution. It is a figure which shows 3rd Embodiment of the optical waveguide component of this invention. It is a figure which shows the cross section of the core of an optical waveguide, and a clad. It is a figure which shows the state by which only the bending part was reduced in diameter. It is a figure which shows the cross section of the fixing member of the optical waveguide component in which the embodiment of FIG. 10 was positioned and fixed. It is a figure which shows the example of a measurement result of the bending loss in a core / area ratio.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
<First Embodiment>
FIG. 1 is a diagram showing a preferred embodiment of the optical waveguide of the present invention. 1A and 1B show an optical waveguide 1, an optical waveguide component 100, and a bending portion manufacturing apparatus 200 for the optical waveguide 1.

  An optical waveguide 1 shown in FIG. 1A is, for example, a silica-based optical fiber, and has a constant refractive index difference between a core and a clad over the entire length. The optical waveguide 1 is an optical fiber having a core 2 and a clad 3 covering the core 2. The outer diameter D of the cladding 3 of the optical waveguide 1 is a GI fiber (graded index optical fiber) having a core diameter S of 62.5 μm, for example, 125 μm. This GI fiber is an example of an optical fiber having an outer diameter of 50 μm or more.

  The linear optical waveguide 1 shown in FIG. 1 (A) is formed by heating the bent portion 10 as shown in FIG. 1 (B) using the bent portion manufacturing apparatus 200 shown in FIG. As illustrated in FIG. 1B, the bending portion manufacturing apparatus 200 includes two electrodes 4 and 5 and a control unit 6, and the control unit 6 energizes the electrodes 4 and 5 to provide electrodes 4 and 5. Arc discharge 7 is generated between the two. The arc discharge 7 is generated in the heating target portion 9 of the linear optical waveguide 1 to form the bent portion 10 as shown in FIG.

  When the desired heating target portion 9 of the linear optical waveguide 1 shown in FIG. 1 (A) is heated by the arc discharge 7 shown in FIG. 1 (B), the heating target portion 9 is above the bending point and below the softening point. Therefore, the heating target portion 9 of the optical waveguide 1 shifts to a processing state (a state where processing such as bending is possible). Then, the heated portion 9 that has shifted to the processed state is bent into a curved shape with a predetermined bending radius R shown in FIG. 2 to form a bent portion 10, and the shape is stabilized by being cooled.

  In this way, when the bent portion 10 is formed, the bent portion 10 of the optical waveguide 1 is bent at a high temperature and is cooled to room temperature (room temperature) after being bent, so that distortion due to bending does not occur. That is, the bent portion 10 of the optical waveguide 1 is bent in a state not less than the bending point and not more than the softening point, and is processed so that the bent state becomes an initial state. When the optical waveguide 1 is deformed below the bending point, distortion occurs, and when the distortion increases, the optical waveguide 1 breaks. After the bent portion 10 is processed above the bending point, the shape is used without deformation. It is said. For this reason, at the time of use, distortion does not occur and it does not break.

  In the optical waveguide component 100 according to the embodiment of the present invention, the object is to reliably and easily change the direction of the optical waveguide in a minute space. That is, the optical waveguide 1 according to the embodiment of the present invention can change the waveguide direction of light by 90 degrees with a small bending portion 10 and a small bending loss. For this reason, the size which can be practically used is defined from the physical size of the optical waveguide 1 to be used.

  FIG. 2 shows an embodiment of the bent portion 10, but the bending radius R of the optical waveguide 1 is preferably 5.0 mm or less. In this way, by setting the bending radius R to 5.0 mm or less, the optical waveguide 1 can be easily arranged even in an indoor or narrow space where arrangement is limited.

  Setting the bending radius R to 5.0 mm or less makes use of the advantage of employing the method for manufacturing an optical waveguide of the present invention. That is, when the bending radius R exceeds 5.0 mm, if a small-diameter optical fiber is used, the fracture strain may not be reached depending on the value of the bending radius R.

  As for the size of the other part of the optical waveguide component 100, the diameter (outer diameter) D of the optical waveguide 1 is preferably 50 μm or more, as shown in FIG. That is, considering the radius R and the diameter D described in FIGS. 1B and 2, it is physically possible to bend the bending radius R less than 50 μm with respect to the optical waveguide 1 having the diameter D of 50 μm. Impossible. In addition, since it is not easy to handle an optical waveguide having a diameter D of less than 50 μm, the minimum outer diameter D of the optical waveguide 1 is regulated to, for example, 50 μm to ensure ease of handling, and the numerical value of the bending radius R As for, it is set as the structure which implement | achieves bending physically by setting it as 10 times the minimum diameter of the optical waveguide 1 to be used. In the present embodiment, an optical fiber having a diameter D of, for example, 80 μm is bent at an angle of 90 degrees with a bending radius R of 1.0 mm.

Furthermore, the diameter D of the optical waveguide 1 is set to 125 μm as a preferred embodiment. This is because it can be said that the outer diameter is highly compatible with a typical optical waveguide currently generally used for optical transmission. By using an optical waveguide having a diameter D of 125 μm, the applicable range of the optical waveguide component can be greatly expanded.
Next, with reference to FIG. 3 thru | or FIG. 5, the fixing member which fixes the optical waveguide 1 of the optical waveguide component 100 is demonstrated. 3 is a perspective view showing a preferred embodiment of the optical waveguide component of the present invention, FIG. 4 is a perspective view showing a fixing member of the optical waveguide component shown in FIG. 3, and FIG. It is sectional drawing which shows the structural example of waveguide components.

An optical waveguide component 100 shown in FIG. 3 is obtained by arraying a plurality of optical waveguides 1 and fixing them with a fixing member 120. The fixing member 120 can also be called a fixing means or a connector ferrule. Although FIG. 3 shows an embodiment in which a plurality of optical waveguides 1 are fixed, a single optical waveguide 1 may be used.
In addition, by arranging a plurality of optical waveguides 1 in an array and fixing them with the fixing member 12, it is possible to collectively change the optical waveguide direction by 90 degrees for multi-channel signal light. Further, although not described in detail, the input / output portion of the optical waveguide component 100 is an optical waveguide equivalent to a general optical waveguide and MFD, so that the optical waveguide component 100 is fitted with, for example, guide pins 191 and 192. Thus, it is possible to connect to an external instrument such as another connector by precise alignment.

  The fixing member 120 has a first portion 121 and a second portion 122, and the first portion 121 is a plate-like portion formed along the X direction and has a thickness F1. The second portion 122 is a plate-like portion formed along the Z direction and has a thickness F2. As shown in FIG. 5, the first portion 121 and the second portion 122 have an L-shaped cross section, and the X direction is orthogonal to the Y direction and the Z direction. The butt angle between the first portion 121 and the second portion 122 may basically be matched with the bending angle of the bending portion 10 of the optical waveguide 1.

  A space portion 200 is formed inside the fixing member 120 as shown in FIG. The space portion 200 has a substantially cross-sectional L shape. The space portion 200 communicates with the external space through the opening 170 on the outer surface 161 of the first portion 121 and the outer surface 162 of the second portion 122. The material of the fixing member 120 is not particularly limited, but is made of metal, plastic, or ceramics.

  As shown in FIGS. 3 and 4, the fixing member 120 is provided with positioning portions 130 and 131 so that the optical waveguide 1 can be arranged and held in parallel when a plurality of optical waveguides 1 are arranged. . The positioning portions 130 and 131 are an example of a precise positioning mechanism provided in the fixing member 120 and are guide holes of the optical waveguide 1.

  The positioning unit 130 includes a plurality of positioning holes 140. The positioning mechanism 131 is composed of a plurality of positioning holes 141. The plurality of positioning holes 140 are formed along the X direction in the first portion 121, and the plurality of positioning holes 140 are arranged in series along the Y direction between the guide pins 191 and 191. The plurality of positioning holes 141 are formed in the second portion 122 along the Z direction, and the plurality of positioning holes 141 are arranged in series along the Y direction between the guide pins 192 and 192.

The plurality of positioning holes 140 are connected to one end portion 201 of the space portion 200 shown in FIG. 5, and the plurality of positioning holes 141 shown in FIGS. 3 and 4 are the other end of the space portion 200 shown in FIG. Connected to portion 202.
A connection portion between the plurality of positioning holes 140 and one end portion 201 of the space portion 200 has a tapered portion 203, and a connection portion between the plurality of positioning holes 141 and the other end portion 202 of the space portion 200 is tapered. Portion 204. The plurality of positioning holes 140 and 141 have an inner diameter that can hold the outer peripheral portion of the optical waveguide 1.

  As shown in FIGS. 5 and 3, each optical waveguide 1 is securely held so as to pass through the space portion 200 in a state of being inserted through the positioning holes 140 and 141. The optical waveguide direction is converted by 90 degrees from the input side end (one end side) to the output side end (other end side). As shown in FIG. 5, the target portion 300 that is at least a part of each optical waveguide 1 is disposed in the space portion 200 in an L-shaped state. The target portion 300 includes the bent portion 10 formed as described above.

  As shown in FIG. 5, the fixing length S of the fixing portion 1P where each optical waveguide 1 is fixed by the positioning holes 140 and 141 is as small as 0.5 mm, for example, but is not limited thereto. .

As shown in FIG. 3, the fixing member 120 is positioned and fixed to an external element such as another fixing member or a connector by two guide pins 191 and 191 and two guide pins 192 and 192. It is a mechanism to do.
The two guide pins 191 and 191 are fitted into the guide hole 193 at the first end surface 186 of the first portion 121 and are fixed to protrude in the X direction. The two guide pins 192 and 192 are fitted into the guide hole 194 on the second end surface 188 of the second portion 122, and are fixed to protrude in the Z direction.
FIG. 6 shows a state where the space portion 200 of the fixing member 120 shown in FIG. 5 is filled with a refractive index matching agent that forms the refractive index matching portion 350 for filling. The state where the target portion 300 of each optical waveguide 1 is covered with the refractive index matching agent in the space portion 200 is shown. The refractive index matching agent forming the refractive index matching portion 350 is filled or injected into the space portion 200 from the opening 170.

  The refractive index matching portion 350 is formed on the surface of the target portion 300 of each optical waveguide 1 except for the fixed portion 1P (see FIG. 5) of each optical waveguide 1. In other words, the surface portion of the target portion 300 of each optical waveguide 1 is a refractive index matching agent (refractive index matching portion 350) having a refractive index smaller than the refractive index of the surface portion (cladding portion) of the target portion 300. Filled to be covered. In addition, as a refractive index matching agent which forms the refractive index matching part 350, the thermosetting resin which has a refractive index of about 1.32 is employ | adopted, for example. Further, FIG. 6 shows a state in which the refractive index matching agent is filled in the entire space portion 200 of the fixing member 120. However, the present invention is not limited to this, and at least the refractive index matching is performed on the surface of the target portion 300 of the optical waveguide 1. The part 350 should just be formed (not shown).

  In the optical waveguide component 100 having the structure as described above, the refractive index of the surface portion 19 (cladding portion) of each optical waveguide 1 (optical fiber) is, for example, 1.44, whereas the refractive index of the refractive index matching portion 350 is. Therefore, there is a large refractive index difference of about 8.2% at the interface between the surface portion 19 of the optical waveguide 1 and the refractive index matching portion 350. Due to this refractive index difference, the target portion 300 including the bent portion 10 of the optical waveguide 1 has a good light confinement effect and can prevent leakage of a propagated signal.

  Further, the refractive index matching unit 350 not only embeds the target portion 300 including the bent portion 10 of each optical waveguide 1 in the fixing member 120 to cover the outer periphery of the target portion 300, but also guides the light in the fixing member 120. This also acts as an adhesive for assembling the waveguide component 100. As a result, there is a merit that the inside of the fixing member 120 of the optical waveguide component module 100 has a strong structure.

  Furthermore, in this embodiment, the refractive index distribution of the GI portion in each optical waveguide 1 is a square distribution shape in which the difference between the core center refractive index (1.474) and the clad refractive index is 2%. Considering the refractive index of the portion 350 (thermosetting portion) as a reference, the center of each optical waveguide (optical fiber) 1 has a high refractive index difference of about 10%. The waveguide structure as a whole functions as an optical waveguide having a stepped (generally called dual shape) refractive index distribution as shown in FIG.

  Furthermore, since the optical waveguide component 100 as shown in FIG. 6 has a high refractive index structure, the optical waveguide component 100 can be connected to other modules even in a large-diameter multimode transmission light having a core diameter of 120 μm, for example. Even if the optical waveguide direction of the optical waveguide component 100 is converted by 90 degrees, the transmission loss of the optical signal due to the bent portion 10 of the conversion part is small. For example, in this embodiment, when the bending radius of the optical waveguide 1 is 1 mm, the transmission loss of the optical signal due to the bending is about 0.5 dB.

Second Embodiment
An optical waveguide component 100 according to a second embodiment of the present invention will be described.
The optical waveguide component 100 of the second embodiment has substantially the same configuration as that of the first embodiment except for the characteristics of the refractive index matching unit 350.

  In the second embodiment, a UV curable resin (ultraviolet curable resin) is used as a refractive index matching agent that forms the refractive index matching portion 350. This refractive index matching agent is, for example, a UV curable resin having a refractive index of 1.38. The refractive index matching portion 350 is formed by irradiating and curing ultraviolet rays through an opening 170 by an external light irradiation means. .

  In the second embodiment as well as in the first embodiment, the refractive index matching portion 350 also functions as an adhesive for assembling the optical waveguide component 100 in the fixing member 120. There is an advantage that becomes a strong structure.

  The refractive index matching unit 350 of the second embodiment has a refractive index of 1.38, and the refractive index of the surface portion (cladding portion) of the optical waveguide 1 (optical fiber) is 1.44. At the interface between the surface portion 19 and the refractive index matching portion 350, the refractive index difference is about 6.2%. Although the refractive index difference is smaller than in the first embodiment, the same effect as in the first embodiment can be obtained.

  As described above, the optical waveguide component 100 including the optical waveguide 1 and the refractive index matching portion 350 has a high refractive index structure (a structure in which the refractive index difference between the refractive index matching portion 350 and the clad is large). For example, even in a structure in which a large-diameter multi-mode propagating light having a core diameter of 120 μm or a leakage light that changes the optical waveguide direction by 90 degrees is likely to occur, the transmission loss of the optical signal can be reduced. For example, in this embodiment, when the bending radius of the optical waveguide 1 is 1 mm, the transmission loss of the optical signal due to the bending is about 0.7 dB.

<Third Embodiment>
A third embodiment of the optical waveguide component of the present invention will be described with reference to FIG.
The optical waveguide component 100 of the third embodiment has substantially the same configuration as that of the second embodiment except that the refractive index matching unit 350 (see FIG. 6) is air (space). That is, the space portion 200 of the fixing member 120 of the third embodiment has a hollow structure filled with air since it is not filled with a refractive index matching agent or the like.

For this reason, the surface portion 19 of the target portion 300 of the optical waveguide 1 shown in FIG. 8 is an air interface.
Note that the fixing portions 1P and 1P of each optical waveguide 1 in FIG. 8 are fixed to the inner peripheral surfaces of the corresponding positioning holes 140 and 141 using a thermosetting resin as the adhesive 600, respectively.

  In the optical waveguide component 100 of the third embodiment, since the cladding of the optical waveguide 1 is covered with the space portion 200, the refractive index of air 1, the refractive index of the cladding 1.44, and the central refractive index of the optical waveguide 1 1.47. And the refractive index difference Δ is about 27%.

  In such a structure having a large difference in refractive index, as in the first and second embodiments, the optical waveguide direction of the optical waveguide component 100 is set to 90 degrees even for large-diameter multimode transmission light having a core diameter of 120 μm, for example. Even with a structure for conversion, it is possible to further reduce the transmission loss of the optical signal. For example, in this embodiment, when the bending radius of the optical waveguide 1 is 1 mm, the transmission loss of the optical signal due to the bending is about 0.2 dB.

FIG. 9 schematically shows a preferable cross-sectional shape of the optical waveguide according to the embodiment of the present invention. The outer circle indicates the cladding 3 of the optical waveguide 1, and the inner circle indicates the core 2 of the optical waveguide 1. The radius of the core 2 a, the radius of the cladding 3 is b, is defined as a ^ 2 / b ^ 2 ( = a 2 / b 2) the area ratio of the core 2 and the cladding 3.
An optical waveguide 1 in which the area ratio of the core 2 and the cladding 3 is 1/5 or more is used. By increasing this area ratio, the power of light leaking from the core 2 to the clad 3 at the bent portion 10 shown in FIG. 1 is reduced, and after leaking from the core 2 to the clad 3, the boundary between the clad 3 and the external environment The power of the light reflected back to the core 2 and recombined with the core 2 increases, and as a result of these composite phenomena, it is possible to reduce the loss due to bending at the bent portion 10.

  FIG. 10 shows the vicinity of the bent portion 10 of the optical waveguide 1 according to the embodiment of the present invention. The area ratio between the core 2 and the clad 3 of the optical waveguide 1 does not necessarily have to be established over the entire length of the optical waveguide 1, and preferably the area ratio between the core 2 and the clad 4 only at the bent portion 10 that is bent. Can be established. This is because the bending loss 10 is a particularly effective phenomenon in the light loss reduction effect described above. In FIG. 10, a structure in which the area ratio of the optical waveguide 1 other than the bent portion 10 is smaller than the area ratio of the bent portion 10 is used.

  As an example of the area ratio described above, for example, by bending an optical fiber having an outer diameter of the core 2 of 30 μm and an outer diameter of the cladding 3 of 125 μm, the bent portion 10 is melted with hydrofluoric acid, The outer diameter of the clad was reduced to 65 μm only at the bent portion. In the original diameter of 30 μm / 125 μm, the area ratio is 36/625 = 0.0576, which is smaller than 1/5 (= 0.2). However, by reducing the cladding outer diameter to 65 μm, the area ratio at the bent portion 10 becomes 36/169 = 0.213, and the area ratio of the bent portion 10 is larger than 1/5 (= 0.2). Become. That is, the core / cladding ratio can be increased by reducing the diameter of only the bent portion 10 as compared with the remaining portion.

  As another embodiment of the present invention, an optical fiber having an outer diameter of the core 2 of 62.5 μm and an outer diameter of the cladding of 125 μm is bent, and the bent portion 10 is melted with hydrofluoric acid so that only the bent portion 10 is clad. The outer diameter of 3 is reduced to 85 μm. In this embodiment, since the area ratio before the diameter reduction is 62.5 μm / 125 μm, 1/4 = 0.25, which is larger than 1/5 (= 0.2). For this reason, the condition that the area ratio of the core 2 and the clad 3 is larger than 1/5 is satisfied. However, by reducing the diameter of the cladding, the area ratio at the bent portion 10 becomes 625/1156 = 0.541, which can be much larger than 1/5 (= 0.2). As a result, the bending loss reduction effect at the bent portion 10 becomes more prominent.

  The optical waveguide 1 having the area ratio shown in FIGS. 9 and 10 may have an optical waveguide component structure similar to that of the first to third embodiments. Specifically, in the optical waveguide having an area ratio of the core 2 and the clad 3 of 1/5 or more, the fixing member 120 in FIG. 11 is the same as the fixing member 120 of the optical waveguide component 100 shown in FIGS. It has a structure.

The fixing length S of the fixing part 1P in FIG. 11 is about 0.5 mm at both ends. Preferably, as shown in FIG. 11, a portion other than the fixing portion 1P is formed with a refractive index matching portion 350 such as an ultraviolet curable resin having a refractive index of 1.38 in the fixing member 120. The number of the optical waveguides 1 set in the fixing member 120 is, for example, 12 in a horizontal straight line, and the optical waveguides 1 are arranged at intervals of 250 μm, and can be used for high-density mounting. .
In FIG. 11, the area ratio of the core and the clad is set to 1/5 or more over the entire length of the optical waveguide 1 such as a glass fiber, or the area ratio of the core and the clad is formed only by the bent portion 10 as shown in FIG. Is 1/5 or more.
As shown in FIG. 11, a refractive index matching portion 350 such as this ultraviolet curable resin is formed in the fixing member 12 and also acts as an adhesive for assembling components, so that the inside of the module has a strong structure. There is an advantage.

The refractive index of the surface (cladding) of the optical waveguide (optical fiber) is 1.444, and there is a large refractive index difference of about 4% at the interface between the fiber surface and the ultraviolet curable resin.
The optical fiber functions as an optical waveguide having the entire outer diameter of 125 μm as a core, and the effect of reducing the bending loss due to the area ratio between the core and the clad being 1/5 or more.
Further, in this embodiment, the refractive index distribution of the GI portion which is the core in the optical fiber is a square distribution shape in which the difference between the core center refractive index (1.474) and the clad refractive index is 2%, which is an ultraviolet curable type. Considering the refractive index of the resin portion as a reference, the fiber center has a refractive index difference of about 6%. In this embodiment, the bending radius is 1 mm and the bending loss is about 1.3 dB.

  In still another embodiment, only the bent portion where the outer diameter of the core 2 is 62.5 μm and the outer diameter of the cladding 3 is 125 μm is melted with hydrofluoric acid so that the outer diameter of the cladding is 85 μm. The outside of the cladding is the same as the ultraviolet curable resin having a refractive index of 1.38. At this time, the area ratio between the core 2 and the clad 3 in the bent portion 10 is 625/1156 = 0.541 as described above, and the bending loss reducing effect in the bent portion 10 is significantly affected. The bending loss is about 0.25 dB, and a reduction in loss of about 1 dB is achieved as compared with the example before melting with hydrofluoric acid.

In another embodiment, the core 2 is 30 μm and the cladding 3 is 125 μm GI fiber (refractive index difference Δ is the same as in the previous embodiment). Only the bent portion is melted with hydrofluoric acid, and the cladding outer diameter is reduced to 65 μm. The outside is filled with an ultraviolet curable resin having a refractive index of 1.38.
As described above, the area ratio between the core and the clad is 36/625 = 0.0576, which is smaller than 1/5 (= 0.2) before the diameter reduction, but in the bent portion 10, the area ratio is 36/169 = 0.213. Before the diameter reduction, the bending loss was about 2.3 dB at a bending radius of 1 mm, but after the diameter reduction, the bending loss was reduced to about 0.7 dB. Although the core / cladding area ratio 0.213 in this example is smaller than the area ratio 1/4 before the diameter reduction in the previous example, the bending loss is small because the refractive index distribution and the refractive index difference Δ Are the same and only the core diameter is different from 30 μm and 62.5 μm, the larger 62.5 μm core diameter has a higher number of transmission modes of the optical fiber and the higher order mode is excited. Since the bending loss resistance is low, the loss is considered large.

In another embodiment, 12 fibers are arranged in a horizontal row at a 125 μm pitch using a GI fiber (refractive index distribution shape, refractive index difference Δ is the same as in the previous embodiment) having a core diameter of 50 μm and a cladding diameter of 80 μm. The bent portions 10 were filled with an ultraviolet curable resin having a refractive index of 1.38. The core / cladding area ratio is 25/64 = 0.391 in this case, and the bending loss at a bending radius of 1 mm is about 0.2 dB.
The core / cladding area ratio of this example and the example after the core diameter of 62.5 μm is 0.391 and 0.541, but the present example of 0.391 has a bending loss. Is considered to be due to the difference in the number of modes depending on the size of the core diameter described above. The core diameter of 62.5 μm has a larger number of modes than the 50 μm core diameter of the present embodiment, and higher order modes It is considered that the bending loss is large because the bending loss resistance is small.

  FIG. 12 shows measurement graphs in which bending loss was measured by changing the bending radius for several core / cladding area ratios. The graph of FIG. 12 shows a downward-sloping tendency. When a straight line is approximated, a practical bending loss of 1.5 dB or less is achieved with a core / cladding area ratio of 1/5 = 0.2 or more at a bending radius of 1 mm. Seems to be possible.

Next, another embodiment of the optical waveguide component 100 shown in FIG. 11 will be described. The fixing member 120 of the optical waveguide component 100 in FIG. 11 positions and fixes an optical fiber having an outer diameter a of 80 μm or 125 μm having a GI-type refractive index distribution with a core diameter of 62.5 μm, 50 μm, and 30 μm. .
Specifically, the core / cladding is 62.5 / 125, only the bent portion 10 is 62.5 / 85 (the remaining portion other than the bent portion is 62.5 / 125), 50/80, only the bent portion 10 is 30/65 ( The remaining parts other than the bent part are a total of four types of 30/125).

  The fixing length S of the fixing part 1P of the fixing member 120 is about 0.5 mm at both ends, the inside of the partial fixing member 120 other than the fixing part 1P is a space, and the surface of the optical waveguide is an air interface. That is, the inside of the optical waveguide component 1 has a hollow structure. In this structure, the module is weaker than the structure filled with the ultraviolet effect resin, but in this structure, the hollow portion has an air refractive index of 1, a fiber cladding refractive index of 1.44, and a fiber center refractive index. The optical waveguide structure has a staircase type refractive index distribution of 1.474, and the refractive index difference Δ is about 27%.

  With such a high refractive index difference, for example, even if the large-diameter multimode optical waveguide 1 having a core diameter of 120 μm is connected to the optical waveguide component 1 and its optical waveguide direction is converted by 90 degrees, the conversion unit The transmission loss due to bending of the bent portion 10 is small. When the bending radius of the optical fiber in this embodiment is 1 mm, the bending loss is 1 dB or less in any core / cladding area ratio embodiment. For example, the number of optical waveguides is 12 in a horizontal line with 250 μm intervals or 125 μm intervals (50/80 example), and can be used for high-density mounting.

  In each embodiment, a GI fiber having an outer diameter of 125 μm or 80 μm and a core diameter of 62.5 μm, 50 μm, or 30 μm was used, but these sizes are merely examples of implementation, and are not limited to these values. It is essential that the area ratio of the core and the clad is 1/5 or more. Further, the refractive index distribution of the core is not limited to the GI fiber of the embodiment, and can be applied to an arbitrary distribution such as a step index or a W type. Similarly, the refractive index difference Δ is not limited to the refractive index difference Δ of the embodiment.

In the optical waveguide 1 according to the embodiment of the present invention, the part to be heated of the optical waveguide 1 is heated to shift to the processing state, and the heating target part 9 that has shifted to the processing state is bent by bending with a predetermined bending radius. The portion 10 is formed, and the bent portion 10 is cooled and the shape is stabilized. The bending portion 10 that shifts to the processing state is accommodated in the space portion 200 of the fixing member 120, and the bending portion 10 accommodated in the fixing member 120 has a light refractive index smaller than the refractive index of the surface portion of the bending portion 10. It is formed by filling the surface portion 19 with the substance 350.
As a result, the structure is simple, the number of parts is small, the optical fibers need not be aligned at the part to be bent, and the multi-mode optical waveguide has a large diameter with a small bent part bent at a desired radius. Can also change the waveguide direction of light. In the optical waveguide 1 of the present invention, the bent portion 10 is heated to a temperature within the range of the bending point or more and the softening point or less to shift to the processed state. Thereby, when heating, it can be made to shift to a processing state reliably.

  The optical waveguide 1 of the present invention is an optical fiber having a core having an outer diameter of 50 μm or more and a clad covering the core, an all-core optical fiber having only the core, or a glass rod having only the clad.

In the optical waveguide of the present invention, the bending radius of the optical waveguide is preferably 5.0 mm or less. Thereby, an optical waveguide can be arranged even in a small space or corner.
In the optical waveguide component of the present invention, a plurality of optical waveguides are preferably arranged in an array, and at least a part of the plurality of optical waveguides is fixed by the fixing member having a positioning mechanism.

  In the optical waveguide component of the present invention, the refractive index matching portion that covers the surface of the optical waveguide only needs to have a refractive index lower than that of the cladding on the surface of the optical waveguide, and the material is an ultraviolet curable resin, a thermosetting resin, or air. There may be. Any material can increase the refractive index difference at the interface between the optical waveguide and the clad, thereby suppressing optical transmission loss.

By the way, this invention is not limited to the said embodiment, A various modified example is employable.
For example, when the bent portion manufacturing apparatus 200 in FIG. 1 forms the bent portion 10 in the optical waveguide 1, in order to heat the desired heating target portion 9 of the optical waveguide 1, heating is performed by arc discharge. Yes. However, the bending portion manufacturing apparatus 200 is not limited to this, and various means such as heating by a burner and heating by a furnace can be adopted.

In the embodiment of the present invention described above, for example, a GI fiber (graded index multimode optical fiber) having a core diameter of 62.5 μm and an outer diameter of 125 μm is used as the optical waveguide. This GI fiber is an example of an optical fiber having a core having an outer diameter of 50 μm or more and a clad covering the core.
However, the present invention is not limited to this, and in the embodiments and examples of the present invention, the optical waveguide may be an all-core type optical fiber having only a core or a glass rod type optical fiber having only a clad. Each embodiment of the present invention can be arbitrarily combined.

The optical waveguide of the present invention can function as an optical waveguide having a high refractive index structure by utilizing the difference in optical refractive index with the material outside the optical waveguide of this kind, and the material of the optical fiber. It is not limited to the refractive index distribution of the optical fiber or the outer diameter of the optical fiber.
Examples of optical waveguide materials include quartz, all plastic, and plastic cladding.

  In the illustrated optical waveguide 1, the light changing direction is 90 degrees, but the angle is not limited to 90 degrees, and an arbitrary angle can be selected.

DESCRIPTION OF SYMBOLS 1 Optical waveguide 1P Fixed part of optical waveguide 4,5 Electrode 6 Control part 9 Heating part 10 Bending part 19 Surface part of optical waveguide 1 100 Optical waveguide component 120 Fixing member 121 First part of fixing member 122 Second of fixing member Part 130 Positioning part (positioning mechanism)
131 Positioning part (positioning mechanism)
140 Positioning hole 141 Positioning hole 170 Opening portion 200 Optical waveguide bending portion manufacturing apparatus 300 Target portion

Claims (9)

An optical waveguide having a bent portion in which the target portion is bent in a curved shape with a predetermined bending radius;
A fixing member for storing at least the bent portion of the optical waveguide,
The optical waveguide is a multimode optical fiber having a core and a clad covering the core,
A cross-sectional area ratio of the core and the clad of the bent portion is 1/5 or more;
A diameter of the bent portion is 50 μm or more;
The fixing member has a fixing portion that directly fixes both sides of the bent portion of the optical waveguide, and a space portion that stores the bent portion,
The space portion is an optical waveguide component filled with a refractive index matching agent having a refractive index smaller than the refractive index of the surface portion of the bent portion,
The fixing member includes an inner bend of the optical waveguide has an opening on the outer surface of the fixing member along the both sides of the linear portion of the bending portion of the optical waveguide, the refractive through the opening Rate matching agent can be filled,
The optical waveguide component, wherein the refractive index matching agent is a UV curable resin or a thermosetting resin.   The optical waveguide component according to claim 1, wherein an outer diameter of the bent portion of the optical waveguide is smaller than an outer diameter of the linear portion.   The optical waveguide component according to claim 1, wherein an outer diameter of the core of the bent portion is 30 μm or more.   The optical waveguide component according to claim 1, wherein a diameter of the bent portion is 125 μm or less.   The optical waveguide component according to any one of claims 1 to 4, wherein a bending radius of a bent portion of the optical waveguide is 5.0 mm or less.   6. The optical waveguide component according to claim 1, wherein a plurality of the optical waveguides are arranged. Heating the heating target portion of the optical waveguide, bending the heating target portion in a curved shape with a predetermined bending radius, and forming a bent portion;
Storing the optical waveguide in a fixing member that directly fixes both sides of the bent portion of the optical waveguide, and a fixing member having a space that stores the bent portion;
Filling the space with a refractive index matching agent having a refractive index smaller than the refractive index of the surface portion of the bent portion;
The optical waveguide is a multimode optical fiber having a core and a clad covering the core,
A cross-sectional area ratio of the core and the clad of the bent portion is 1/5 or more;
The bending portion of the diameter is not less 50μm or more the fixing member, an inner bend of the optical waveguide, the opening on the outer surface of the bending the fixing member along the linear portion of each side portion of the optical waveguide And filled with the refractive index matching agent from the opening,
The method of manufacturing an optical waveguide component, wherein the refractive index matching agent is a UV curable resin or a thermosetting resin. Before storing the optical waveguide in the fixing member,
8. The method of manufacturing an optical waveguide component according to claim 7, further comprising a step of making an outer diameter of the bent portion of the optical waveguide smaller than an outer diameter of the straight portion. 9. The method of manufacturing an optical waveguide component according to claim 8, wherein the step of reducing the outer diameter of the bent portion of the optical waveguide is a step of dissolving the clad of the bent portion with hydrofluoric acid.

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