JP2004177606A - Coupling method of optical device and optical fiber, and optical device with optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the positioning of the core part of an optical fiber and the optical waveguide part of an optical device easily and with high accuracy, and to reduce transmission loss in a connecting part, with respect to the coupling method of the optical device and the optical fiber, and the optical device with the optical fiber. <P>SOLUTION: In this coupling method, the optical fiber is inserted and arranged in the optical fiber mounting part of an optical device resin substrate in which an optical waveguide and the optical fiber mounting part are formed (S101), resin for adhesion (adhesives) is applied to the optical fiber mounting part (S102) and the optical fiber is drawn towards a desired direction with tensile stress which is locally generated by partially hardening the resin for adhesion and the position of the fiber is adjusted (S103). After the adjusting of the position of the optical fiber and the temporary stopping of the fiber are completed, the whole resin for adhesion is hardened and a coupling process is completed (104). The fixing of the position of the fiber is realized by adjusting positions of the optical device and the fiber. Since the initial positioning of the fiber is attained by simple positioning, the productivity is increased. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to coupling between an optical waveguide and an optical fiber of an optical waveguide type optical device used in the optical communication field and the optical information processing field.
[0002]
[Prior art]
Conventionally, as a method of coupling an optical waveguide and an optical fiber of an optical waveguide type optical device, a guide groove having a diameter similar to the optical fiber diameter on the surface is formed on a transparent substrate guide groove formed along a branch circuit pattern. It is known that a plastic optical fiber is wired, and then a transparent resin having a refractive index higher than the refractive index of the substrate material constituting the substrate is poured into the branch portion of the guide groove, cured and bonded to the plastic optical fiber. (For example, see Patent Document 1). Also, a molded part having an optical transmission path structure preform and an optical fiber guiding structure (where the optical transmission path of the optical transmission path structure preform is achieved by post-processing) and at least one connected A method of manufacturing a passive integrated optical device made of a polymer material, comprising an optical fiber-shaped optical transmission body, comprising forming a polymer having a step at each transition between an optical fiber guide structure and a preformed portion for an optical transmission line structure. 2. Description of the Related Art There is known a method for manufacturing a device for an optical transmission line network, in which a component is manufactured and both structures are manufactured at the same time (for example, see Patent Document 2). In addition, in order to minimize the transmission loss at the connection part, high-precision positioning is required for the connection between the optical device and the optical fiber. Normally, the transmission loss is minimized by using a six-axis stage controlled in XYZ axes and angle. Alignment is performed while monitoring a certain position. This alignment accuracy is required to be within 1 μm for a single mode optical fiber.
[0003]
[Patent Document 1]
JP-A-58-95305
[Patent Document 2]
JP-A-6-3545
[0004]
[Problems to be solved by the invention]
However, in the method described in Patent Document 1 described above, the optical fiber holding portion and the optical waveguide are manufactured in an integral structure, and the optical fiber is embedded in the optical waveguide, and light leaks into the optical fiber holding portion. However, there is a problem that the loss is large. Further, in the method described in Patent Document 2 described above, since the alignment of the optical waveguide and the optical fiber is performed based on the outer shape of the optical fiber, the outer diameter of the optical fiber and the size and positional accuracy of the core portion of the optical fiber are reduced. It becomes a problem. Further, when the optical fiber is embedded in the optical fiber guide structure, fine adjustment of the position of the optical fiber becomes difficult. In addition, when an optical device is manufactured in an integrated structure with an optical fiber, when the optical fiber and the optical waveguide are displaced from each other, adjustment becomes difficult, and there is a problem that the optical device cannot be used.
[0005]
In order to reduce the transmission loss at the connection part, when connecting the optical device and the optical fiber, the alignment is performed while monitoring the position where the transmission loss is minimized by using the XYZ axes and the 6-axis stage whose angle is controlled. Has also been done. An optical fiber is composed of a core part that propagates light and a clad part outside the core part. It is important to align (align) the core part of the optical fiber with the optical waveguide part of the optical device. is there. This alignment accuracy is required to be within 1 μm for a single mode optical fiber. The time spent for such alignment contributes to an increase in the cost of the optical device.
[0006]
The present invention solves the above-described problems, and can accurately align a core portion of an optical fiber and an optical waveguide portion of an optical device with a simple configuration and method, and can reduce transmission loss at a connection portion. It is an object of the present invention to provide a method of coupling an optical device and an optical fiber, and an optical device with an optical fiber.
[0007]
Means for Solving the Problems and Effects of the Invention
In order to achieve the above object, the invention of claim 1 provides a light-curing adhesive or a thermosetting adhesive between an optical device having an optical waveguide which is a component of an optical circuit and an optical fiber for transmitting light. In a method of coupling an optical device and an optical fiber by applying and curing an agent, a step of inserting an optical fiber into an optical fiber attaching portion of the optical device, and applying an adhesive to the attaching portion where the optical fiber is inserted. This is a method for coupling an optical device and an optical fiber, comprising a step of applying and a step of adjusting the position of the optical fiber.
[0008]
In the above coupling method, the position of the optical fiber can be fixed while adjusting the position of the optical device and the optical fiber. In addition, since the initial optical fiber positioning can be simplified positioning, productivity of the positioning step is improved.
[0009]
According to a second aspect of the present invention, in the method for bonding an optical device and an optical fiber according to the first aspect, when a light-curable adhesive is used as the adhesive for fixing the position of the optical fiber, the optical device for curing the adhesive is used for the optical device. It forms a wave path.
[0010]
In the above method, a desired position can be easily irradiated with light without using equipment (scanner, movable table, etc.) for controlling the irradiation position at the time of light irradiation.
[0011]
According to a third aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the second aspect, a plurality of optical fiber position adjusting optical waveguides are provided at symmetrical positions separated from the optical waveguides constituting the optical circuit by a radius of the optical fiber or more. The optical device provided is used.
[0012]
In the above method, the curing shrinkage of the optical fiber can be controlled uniformly, and the optical fiber misalignment in all directions can be corrected. In addition, even when the number of light sources is small, curing shrinkage can be uniformly generated. In addition, when arranged symmetrically, the curing shrinkage stress becomes uniform, and the adjustment of the amount of movement becomes easy to control.
[0013]
According to a fourth aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the third aspect, an optical device provided with optical fiber position adjusting optical waveguides having mutually different cross-sectional areas is used.
[0014]
In the above method, the amount of curing shrinkage of the photocurable adhesive applied to each part can be easily controlled only by selecting the optical fiber position adjusting optical waveguide.
[0015]
According to a fifth aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the third aspect, an optical device provided with an optical fiber position adjusting optical waveguide having an end face facing the side face of the optical fiber is used.
[0016]
In the above method, the amount of adhesive that can be cured at one time increases, and the efficiency of optical fiber positioning improves.
[0017]
According to a sixth aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the third aspect, the plurality of optical fiber position adjusting optical waveguides are located at symmetrical positions separated from the optical waveguides constituting the optical circuit by substantially the radius of the optical fiber. Is used.
[0018]
In the above method, the position of the optical fiber is automatically and appropriately determined without adjusting the amount of light incident on the optical waveguide for adjusting the position of the optical fiber.
[0019]
According to a seventh aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the sixth aspect, light is emitted by detecting reflected light at the end face of the optical fiber, the light incident on the optical waveguide for adjusting the position of the optical fiber. This is to select the optical waveguide for adjusting the position of the optical fiber.
[0020]
In the above method, it is possible to easily measure the direction of displacement of the optical fiber, and it is possible to cure only the photocurable adhesive on the opposite side that is displaced.
[0021]
According to an eighth aspect of the present invention, there is provided a method for coupling an optical device and an optical fiber according to the second aspect, wherein a plurality of types of polymerization initiators having different wavelength characteristics are mixed with each other by using a photocurable adhesive, and the optical waveguide for adjusting an optical fiber position is provided. By changing the wavelength of light incident on the light-curing adhesive, the curing shrinkage of the photocurable adhesive is controlled.
[0022]
In the above method, it is possible to control the amount of displacement of the optical fiber by changing the wavelength of the light to be irradiated.
[0023]
According to a ninth aspect of the present invention, in the method of coupling the optical device and the optical fiber according to the eighth aspect, the concentrations of the plural kinds of the polymerization initiators are different.
[0024]
In the above method, the amount of displacement of the optical fiber can be finely adjusted by changing the wavelength of the irradiated light.
[0025]
According to a tenth aspect of the present invention, in the method for bonding an optical device and an optical fiber according to the second aspect, a photocurable resin having a different curing wavelength is applied to each direction at least in the vertical and horizontal directions between the optical device and the optical fiber. After that, the light of the curing wavelength of the resin applied on the opposite side to the direction of the displacement is irradiated through the optical fiber position adjusting optical waveguide.
[0026]
In the above method, the position of the optical fiber can be adjusted only by selecting the wavelength of the incident light.
[0027]
According to an eleventh aspect of the present invention, in the method for bonding an optical device and an optical fiber according to the second aspect, an optical fiber end face is provided with a light-curable adhesive which has a light transmittance equivalent to that of an optical waveguide of the optical device when cured. On the side of the optical fiber, an adhesive having an adhesive strength equal to or higher than that of the photocurable adhesive used for the end face is used.
[0028]
In the above method, it is possible to reduce the loss of the optical device.
[0029]
According to a twelfth aspect of the present invention, in the method for coupling an optical device and an optical fiber according to the second aspect, in the step of inserting the optical fiber into the optical device, the optical fiber having a convex end surface is provided on the surface facing the optical fiber end surface. The position of the optical fiber is roughly determined by inserting into an optical device having a concave portion and adjusting the concave and convex portions.
[0030]
In the above method, since the position of the optical fiber is determined to some extent, the width of fine adjustment by the adhesive can be small.
[0031]
According to a thirteenth aspect of the present invention, there is provided an optical device with an optical fiber manufactured by the method according to any one of the first to twelfth aspects.
[0032]
In the above configuration, since the position adjustment of the optical fiber is efficient, it is possible to reduce the cost of assembling the optical fiber and the device, and since the position adjusted with high accuracy can be obtained, an optical device having a small optical connection loss can be obtained. can get.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for coupling an optical device and an optical fiber and an optical device with an optical fiber according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals are given to common members in the drawings, and redundant description will be omitted. Generally, a photo-curable adhesive or a thermosetting adhesive shrinks during curing. If there is an attached fixed object, this shrinkage generates stress. By utilizing this stress, the position of the optical fiber can be adjusted.
[0034]
First, an outline of the combining method will be described. FIG. 1 shows a process flow of a method for coupling an optical device and an optical fiber. An optical fiber is inserted and arranged in an optical fiber attaching portion of an optical device resin substrate on which an optical waveguide and an optical fiber attaching portion are formed (S101). Next, an adhesive resin (adhesive) is applied to the optical fiber attachment portion (S102). Next, the position of the optical fiber is adjusted while pulling the optical fiber in a desired direction by the tensile stress locally generated by partially curing the adhesive resin (S103). After the position adjustment of the optical fiber and the temporary fixing of the optical fiber are completed, the entirety of the adhesive resin is cured, and the bonding process is completed (S104).
[0035]
(Basic method of optical fiber position adjustment)
Next, details of the combining method for each stage of each process will be described. 2 (a) to 2 (j) are a sectional view and a plan view at each stage of forming an optical device with an optical fiber. The optical device (substrate) 1 is composed of an optical waveguide 2 and a clad material surrounding the optical waveguide. The optical fiber mounting part 3 provided on a part of the clad material has a margin of several μm from the diameter of the optical fiber so that the alignment between the optical waveguide 2 and the core part 5 of the optical fiber 4 can be easily performed. It is formed as a groove. A single mode optical fiber used for optical communication generally has a cladding layer having an outer diameter of 125 μm and a mode field diameter (core diameter) of about 9 μm. In the case of multi-mode, a core diameter of 50 μm or more is used. Hereinafter, the case of the single mode in which higher mounting accuracy is required will be described. In a single-mode optical fiber, the alignment accuracy between the optical waveguide and the optical fiber is required to be 1 μm or less, so that high-accuracy alignment is required. In the present invention, when the shape of the optical waveguide is 6 μm in width and the search is 6 μm, the width of the groove of the optical fiber mounting portion 3 is 129 μm, and the search requires the center of the optical fiber to coincide with the center of the optical waveguide structure. 0.5 μm. Since the outer diameter of the optical fiber is 125 μm, there is a margin of 2 μm on one side, and the optical fiber is simply positioned in this range as shown in FIGS.
[0036]
Subsequently, as shown in FIGS. 2E and 2F, an adhesive 61 is applied to the optical fiber mounting portion by dropping or the like. Next, as shown in FIGS. 2 (g) and 2 (h), the position of the optical fiber 4 is measured, and if there is a shift with respect to the position of the optical waveguide 2, the optical fiber is bonded to the opposite side of the shift direction. When the optical fiber 4 is displaced downward in the figure, for example, heat L1 for curing the adhesive is locally applied from above to move the optical fiber 4 upward, or the adhesive is irradiated with light L1. 61 is cured locally. In the case of a photocurable adhesive, light can be irradiated particularly in a spot manner. Further, the substrate of the optical device having the optical waveguide is usually a transparent resin substrate, and light can be applied to the adhesive of the optical fiber mounting portion through the resin substrate. The light irradiation is performed by condensing the light with a lens or the like so that the adhesive starts to cure from the side opposite to the adhesive 61 (the wall surface of the mounting portion) with respect to the optical fiber 4, or is converted into a linear light by a cylindrical lens or the like. In the case of a thermosetting adhesive as well, the heat source is spot-shaped so that only a small area can be cured. After the position adjustment of the optical fiber and the temporary fixing of the optical fiber are completed, as shown in FIGS. 2 (i) and (j), when the entire bonding resin is, for example, a photo-curing resin, the adhesive resin is applied from both sides of the optical fiber. Cured by light L2 and R2. The adhesive 61 having fluidity becomes the adhesive 6 cured and solidified by the light energy.
[0037]
One of the photo-curable adhesives used in the present invention is an ultraviolet-curable acrylic resin. When this adhesive was used, for example, light from a 100 W mercury lamp was condensed to φ0.2 mm by an optical fiber and a lens so as to irradiate only one side of the optical fiber. The energy density of ultraviolet rays was 100 mW per square cm, and irradiation was performed for several tens of seconds. Since the curing of the adhesive starts from the position where the light was irradiated, the irradiation was performed on the outer diameter of the optical fiber at the tip of the optical fiber near the optical waveguide where the coupling position accuracy is required. By such alignment with the adhesive and light irradiation, the connection loss of the optical fiber was reduced from 1.5 dB to 0.4 dB by simple positioning alone.
[0038]
An epoxy resin can be used as the thermosetting adhesive. The curing condition of the resin used was that the resin was completely cured at 85 ° C. for 2 hours, so the initial positioning was performed by condensing infrared rays and irradiating them for several minutes, and then heating the whole to obtain the desired light. Fiber coupling was performed.
[0039]
(Adhesive curing waveguide / Optical fiber position adjustment optical waveguide)
Next, an optical device provided with a dedicated adhesive curing waveguide (optical fiber position adjusting optical waveguide) for guiding light for photocuring when a photocurable adhesive is used will be described. 3A to 3J are a cross-sectional view and a plan view at each stage of forming an optical device with an optical fiber. As described above, the case of the single mode will be described. When the shape of the optical waveguide 2 on the optical device 1 is 6 μm in width and 6 μm in depth, the dimensions of the optical fiber 4 attaching portion 3 are 129 μm in width, and the depth must be such that the center of the optical fiber coincides with the center of the optical waveguide groove. And 65.5 μm. The adhesive curing waveguide 21 is provided in parallel with the original optical waveguide 2 so that when the optical fiber 4 is mounted, the outer diameter of the optical fiber is irradiated with light. Therefore, the interval between the adhesive curing waveguides 21 provided at diametrically symmetric positions of the optical fiber 4 is 125 μm. The adhesive curing waveguide 21 may be three-dimensionally arranged in a cylindrical shape along the outer diameter of the optical fiber. The cross-sectional shape of the adhesive curing waveguide 21 can be easily manufactured at the same size as the cross-sectional shape of the optical waveguide 2 at the time of manufacturing the optical device substrate, and the size can be changed as necessary. By providing and using such an optical fiber position adjusting optical waveguide, when irradiating the adhesive curing light as shown below, without using equipment for controlling the irradiation position, easily to a desired position. Light irradiation becomes possible.
[0040]
The optical fiber 4 is inserted into the fiber mounting part 3 of the optical device 1 as shown in FIGS. The groove width of the optical fiber mounting portion 3 has a margin of 2 μm on one side with respect to the outer diameter of the optical fiber 4. Next, as shown in FIGS. 3E and 3F, an optical fiber fixing adhesive 61 is applied around the optical fiber 4. It is efficient to use the same adhesive 61 as the core material for forming the optical waveguide 2. However, from the viewpoint of the difference in the refractive index from the cladding material, the optical characteristics, the adhesiveness to the optical fiber, etc. Is selected. Next, as shown in FIGS. 3G and 3H, the curing light L3 or R3 is incident on the adhesive curing waveguide 21, and a part of the adhesive 61 is cured. Since the curing of the adhesive 61 is accompanied by shrinkage, the shrinkage generates a tensile stress. That is, when the adhesive 61 is cured, a tensile stress is generated in the cured adhesive, and the optical fiber moves in that direction. An acrylic UV curable resin can be used as the adhesive. Light can be incident on a waveguide appropriately selected from a plurality of adhesive curing waveguides, and the optical fiber can be guided to an optimal position. Finally, as shown in FIGS. 3 (i) and 3 (j), the entire adhesive 61 is collectively cured by light irradiation L4 and R4.
[0041]
(Example of structure of optical waveguide for adjusting optical fiber position)
Next, an optical device having several structures of an optical fiber position adjusting optical waveguide will be described with reference to FIGS. FIGS. 4A to 4D show the position adjusting optical waveguide 22 in which the incident light side sectional area is larger than the outgoing light side sectional area. For example, if the photocurable adhesive used for optical fiber placement adjustment requires irradiation of light of 100 mW per square cm for about 60 seconds, the light guide side light source side optical waveguide cross-sectional area should be increased. It is possible to cope with this by improving the incident efficiency. In this case, for example, the incident light side of the optical fiber position fixing optical waveguide 22 may have an optical waveguide width of 100 μm and a search of 7 μm, and the emission light side may have an optical waveguide width of 7 μm and a depth of 7 μm.
[0042]
FIGS. 5A and 5B show an optical device having a structure in which a plurality of optical fiber position adjusting optical waveguides 23 and 24 are formed in a branch shape. When coupling an optical device and an optical fiber using such an optical device, when the position adjusting optical waveguides 23 and 24 have a branching optical waveguide structure and a structure in which light is branched evenly, Since the contraction in the vertical direction in the drawing occurs evenly, the movement by the optical fiber position adjustment is performed only in the horizontal direction (the horizontal direction in the drawing). The above-described branching structure is a description of a splitter that splits light energy evenly. However, by changing the ratio of energy distributed by branching, more efficient positioning may be possible. When the center of the core of the optical fiber is accurately aligned with the center of the waveguide (core portion) of the optical waveguide device by pressing the optical fiber into the optical fiber mounting groove, the pressing force on the substrate side from the center of the optical fiber should be increased. In this case, the adhesive can be aligned in the up-down direction, and for this purpose, a desired adhesive curing light irradiation can be performed by adopting a branch structure that increases the amount of light downward.
[0043]
FIGS. 6 and 7 show an optical device having a structure having a plurality of optical waveguides having different cross-sectional areas as optical waveguides for adjusting the fiber position. The curing amount of the photocurable resin is determined by the energy density and time of the irradiated light. When irradiating light from an optical waveguide, the stress generated due to curing shrinkage may be small because the irradiation area is limited. For this reason, when a plurality of adjustment optical waveguides 25, 26, and 27 having different optical waveguide cross-sectional areas are used for adjustment as shown in FIG. 6, when the displacement amount of the optical fiber is large and the necessary movement amount is large. In order to finely adjust the adhesive by using an optical waveguide 27 having a large cross-sectional area, it is preferable to use an optical waveguide 25 having a small cross-sectional area. The optical waveguide for position adjustment may have a width of 5 μm to 10 μm and a depth of 5 μm to 50 μm, for example. The optical waveguides for adjustment may be arranged in a plane as shown in FIG. 6, or may be arranged in a three-dimensional manner as the waveguides 28 and 29 shown in FIG.
[0044]
FIGS. 8A and 8B show an optical device having a structure in which fiber position adjusting optical waveguides 30 and 31 are provided so that the adhesive can be cured from the side of the optical fiber. To align the optical fiber 4 and the optical waveguide 2, it is necessary to control the placement of the optical fiber core and the optical waveguide 2 with sub-micron accuracy. In particular, it is important to align the end face of the optical fiber which is the optical coupling portion. As can be seen from the above examples, when irradiating light for curing the adhesive from the end face of the optical fiber, the diameter of the optical fiber is usually as small as φ125 μm, and the amount of the adhesive that can be cured at one time is limited. is there. Therefore, an optical waveguide is manufactured so that the adhesive can be cured from the side of the optical fiber. As shown in FIG. 8 (a), when the optical fiber position adjusting optical waveguide 30 is provided in a direction facing the side surface of the optical fiber 4, a larger area can be cured at a time, and the moving amount of the optical fiber can be reduced. Many can be taken. Further, as shown in FIG. 8B, the forming direction of the optical waveguide may be the oblique direction in the longitudinal direction of the optical fiber 4, and various variations can be used.
[0045]
(Optical fiber position adjustment function)
Next, a description will be given of a fiber position adjusting function in the case where the optical fiber position adjusting optical waveguide 21 is provided symmetrically with respect to the position of the optical waveguide 2. As shown in FIG. 9A, a plurality of optical fiber adjusting waveguides 21 and 21 are symmetrically arranged at positions separated from the optical waveguide 2 by a radius of the optical fiber 4, and an adhesive 61 is applied to the optical fiber 4. Suppose At this time, if the position of the optical fiber is shifted downward in the drawing, the upper light L12 of the light L12 and R12 simultaneously incident on the optical fiber position adjusting optical waveguide reaches the adhesive 61 and irradiates it. The curing of the adhesive starts. When curing starts, stress is generated by curing shrinkage, and the optical fiber position moves in an appropriate direction, that is, upward. On the other hand, the light R12 incident below the optical fiber is incident or reflected on the optical fiber at the end face of the optical fiber and does not directly reach the adhesive 61, and the curing of the adhesive does not proceed. No stress occurs. In this manner, the position of the optical fiber is automatically determined to be an appropriate position by operating the optical fiber position automatic adjustment function. Therefore, it is necessary to adjust the light amounts of the light L12 and R12 incident on the optical fiber position adjusting optical waveguide. There is no.
[0046]
Further, the adhesive for fixing the optical fiber needs to be uniformly cured around the optical fiber. By arranging an optical waveguide for curing the adhesive for fixing the optical fiber at a portion separated by a distance equal to or greater than the radius from the center of the optical fiber, and further arranging a plurality of these along the outer diameter of the optical fiber. In addition, the shrinkage of the adhesive can be uniformly cured. For example, when the optical fiber has an outer diameter of φ125 μm, the optical fiber fixing optical waveguide may be disposed at a distance of 62.5 μm from the center of the optical device optical waveguide core, and the size of the optical waveguide may be 6 μm square. .
[0047]
(Monitor of light for curing adhesive)
Next, a method of monitoring the reflected light of the adhesive curing light and controlling the intensity of the adhesive curing light will be described. As shown in FIG. 10, a plate M for reflecting the adhesive curing light is arranged in the optical fiber position adjusting optical waveguide 32, and the light reflected at the end face of the optical fiber 4 (lights R14 and R15 in the example of the figure) is detected. 8 to detect. The detector 8 determines an optical waveguide 32 having a large amount of reflected light to limit the amount of incident light, and increases the amount of incident light to an optical waveguide having no reflected light. In the case as shown in FIG. 10, the adhesive curing light L13 reaches the optical fiber attaching portion (L14), cures the adhesive 61, and hardly generates reflected light. On the other hand, the light R13 for curing the adhesive is partially reflected by the end face of the optical fiber and returns to the optical waveguide for adjusting the position of the optical fiber because the optical fiber is located at the emission portion. By detecting this light, the direction of displacement can be detected. If the misalignment direction is detected, the light (L13) can enter the other optical waveguide efficiently, that is, intensify, with respect to the misalignment direction.
[0048]
(Adjustment of optical fiber position by characteristics of photocurable adhesive and selection of curing light)
Next, the optical fiber position control by controlling the curing of the adhesive will be described with reference to FIGS. Usually, a polymerization initiator is added to the photocurable adhesive, and when this initiator is irradiated with light, a radical group is generated, and the monomer is polymerized by the effect, and the adhesive is cured. . Since the polymerization initiator has a different wavelength at which the reaction is initiated for each type, it is possible to select and assign light to be cured for each type. Therefore, if a plurality of polymerization initiators are added to the photocurable adhesive, curing can be controlled by the wavelength of light.
[0049]
For example, as a polymerization initiator, 1% by weight of 2-hydroxy-2-methyl-1-phenyl-propan-1-one is 1% (by Ciba Specialty Chemicals Co., Ltd., based on an acrylic ultraviolet curing adhesive). 1% by weight of DAROCUR 1173) and 2-Penzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (IRGACURE 369, manufactured by Ciba Specialty Chemicals Co., Ltd.). As shown in FIG. 11A, an ultraviolet curing adhesive 62 to which such a polymerization initiator is added is applied to the optical fiber 4. Next, the lights L16 and R16 are incident on the optical fiber position adjusting optical waveguide 21 using a mercury lamp whose wavelength is cut off at a wavelength of 400 nm or less by a wavelength cut filter. As shown by the curve A in FIG. 11B, only the IRGACURE 369 reacts at a wavelength of 400 nm or more, so the amount of the cured adhesive becomes very small, and the position of the optical fiber can be finely adjusted. . Next, by taking a wavelength cut filter and irradiating the adhesive with the ultraviolet light L17 and R17, the entire body is cured, so that the optical fiber position adjustment and bonding can be performed efficiently.
[0050]
Further, by adding a plurality of polymerization initiators to the photocurable adhesive, curing can be controlled by the wavelength of light. For example, as a polymerization initiator, 0.2% by weight of 2-hydroxy-2-samethyl-1-phenyl-propan-1-one relative to an acrylic ultraviolet-curing adhesive (Ciba Specialty Chemicals Co., Ltd.) 1.0% by weight of DAROCUR 1173) and 2-Penzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (IRGACURE 369, manufactured by Ciba Specialty Chemicals Co., Ltd.). As shown in FIG. 12, an ultraviolet curing adhesive 63 containing such a polymerization initiator is applied to the optical fiber 4. Further, a plurality of optical devices 1 are provided on both sides of the waveguide 2 like the optical fiber position adjusting waveguides 32 and 35. Next, light L19 and R19 were incident on the optical fiber position adjusting optical waveguides 35 and 35 using a mercury lamp whose wavelength was cut by 400 nm or less using a wavelength cut filter. Curing at this wavelength takes a long time to cure because the amount of the polymerization initiator is small, generates a small stress, and allows fine adjustment. Next, light L18 and R18 having a wavelength of 400 nm or less are also incident, and the adhesive for fixing the optical fiber is uniformly cured, so that the optical fiber position adjustment and bonding can be performed efficiently.
[0051]
Further, when the optical fiber is arranged in the groove of the optical fiber attaching portion, the groove is divided into several parts by the optical fiber. In each of the divided portions, a polymerization initiator having a different polymerization initiation wavelength is arranged for each of the divided portions. As shown in FIG. 13, mercury lamps are used as light sources L64 and L65 for curing the adhesive, and wavelengths to be applied to the adhesive are selectively selected using a wavelength cut filter. For example, it is possible to cut off the light L65 and use only the light L64 for irradiation. For example, light having a wavelength of 200 nm to 500 nm is generated by a high-pressure mercury lamp, and light incident on the optical fiber position adjusting optical waveguide can be selected by a wavelength filter.
[0052]
Regarding the optical fiber bonding portion, the adhesive used for fixing the optical fiber attaches importance to the adhesion to the optical device substrate 1, but the light transmission rate between the optical waveguide 2 and the optical fiber 4 of the optical device is important. To emphasize. In some cases, the fixing adhesive may enter between the end face of the optical fiber and the end face of the waveguide, or a gap may be formed.However, the gap scatters light and increases the loss, thereby adversely affecting the optical characteristics of the optical device. . Therefore, as shown in FIG. 14, a photocurable resin 66 having good characteristics with respect to the wavelength of light intended for use of the optical device is applied between the optical fiber and the optical waveguide in advance. Thereby, it is possible to suppress bubbles generated between the optical fiber 4 and the optical waveguide 2. Next, an adhesive 67 having good adhesiveness is applied to the side surface of the optical fiber. At this time, there is a possibility of mixing with the photocurable resin 66 applied between the optical fiber 4 and the optical waveguide. However, there is no problem as long as the mixing does not occur at least in the region where the optical waveguide 2 and the optical fiber core face each other. In addition, it is necessary to select two adhesives that do not react. For example, the photocurable resin 66 used between the optical waveguide 2 and the optical fiber 4 is made of an acrylic ultraviolet curable resin or fatty tetrafluoropropyl methacrylate, and an epoxy photocurable resin (Epoxy Technology) is provided on the side of the optical fiber. UVO-114) may be used.
[0053]
(Easy positioning with optical fiber end face)
Next, simple positioning of the optical fiber will be described with reference to FIG. By providing the optical fiber 4 having the convex portion Q at the tip of the optical fiber and the concave portion P in the optical device 1, simple positioning can be performed when positioning the optical fiber 4. After such simple positioning, the optical fiber positioning optical waveguide 36 irradiates light L66 and R66 to perform optical fiber positioning. For example, the tip of the optical fiber 4 may be polished to have a convex shape of R100 μm, and the shape of the groove of the optical fiber attachment portion may be shaped so as to match the tip, so that the position of the optical fiber is easily determined. did it.
[0054]
(Optical device with optical fiber)
When the optical fiber coupling method according to the present invention is used, the optical fiber position adjustment becomes efficient and the connection loss is reduced. In addition, the efficiency of the optical fiber connection is improved, and the cost of assembling the optical fiber and the device can be reduced.
[0055]
The present invention can be variously modified without being limited to the above configuration. Further, in the above description, the coupling portion between one optical fiber and the optical device has been described with reference to a partial view. However, the present invention is also applicable to an optical device including a plurality of optical fibers. Light irradiation for curing the adhesive can also be performed from the upper surface or the lower surface of the optical device (in a direction perpendicular to the plane of the drawing).
[Brief description of the drawings]
FIG. 1 is a flowchart of a method for coupling an optical device and an optical fiber according to an embodiment of the present invention.
2A is a cross-sectional view taken along line C1-C1 in FIG. 2B of the optical device according to the coupling method, FIG. 2B is a plan view of FIG. 2A, and FIG. 2C is a diagram in which an optical fiber is inserted into the optical device. (D) is a cross-sectional view of C2-C2, (d) is a plan view of (c), (e) is a cross-sectional view of C3-C3 in (f), showing a state where an adhesive is applied around the optical fiber of the previous figure, (F) is a plan view of (e), (g) is a cross-sectional view taken along line C4-C4 in (h), showing a state in which light is partially applied to the adhesive of the previous figure, and (h) is a view of (g). FIG. 2 (i) is a plan view, FIG. 2 (i) is a cross-sectional view taken along line C5-C5 of FIG.
3A is a sectional view taken along line D1-D1 in FIG. 3B, showing a structure of an optical device according to another embodiment of the present invention, FIG. 3B is a plan view of FIG. 3A, and FIG. (D) is a sectional view taken along line D2-D2 in which an optical fiber is inserted into the device, (d) is a plan view of (c), and (e) shows a state in which an adhesive is applied around the optical fiber in the previous figure (f). , (F) is a plan view of (e), (g) shows a state in which the adhesive in the previous figure is partially irradiated with light, and (D) is a D4-D4 sectional view of (h). (h) is a plan view of (g), (i) is a cross-sectional view taken along line D5-D5 in (j) showing a state in which the entire adhesive is irradiated with light, and (j) is a plan view of (i).
4A is a sectional view taken along line E1-E1 in FIG. 4B, showing the structure of an optical device according to still another embodiment of the present invention, FIG. 4B is a plan view of FIG. 4A, and FIG. FIG. 3D is a cross-sectional view taken along line E2-E2 in (d) showing a state in which the adhesive around the optical fiber inserted into the optical device is partially irradiated with light, and (d) is a plan view in (c).
5A is a sectional view taken along line F2-F2 in FIG. 5B, showing a structure of an optical device according to still another embodiment of the present invention, and FIG. 5B is a sectional view taken along line F1-F1 in FIG.
FIG. 6 is a plan view showing a structure of an optical device according to still another embodiment of the present invention.
FIG. 7 is a sectional view showing a structure of an optical device according to still another embodiment of the present invention.
FIGS. 8A and 8B are plan views each showing a structure of an optical device according to still another embodiment of the present invention.
FIG. 9A is a plan view showing an optical fiber position adjusting method according to still another embodiment of the present invention, and FIG. 9B is a plan view showing a state where the optical fiber position is adjusted.
FIG. 10 is a plan view showing an optical fiber position adjusting method according to still another embodiment of the present invention.
FIG. 11A is a plan view showing an optical fiber position adjusting method according to still another embodiment of the present invention, and FIG. 11B is a characteristic diagram of an adhesive used in FIG.
FIG. 12 is a sectional view showing a structure of an optical device according to still another embodiment of the present invention.
FIG. 13 is a plan view showing an optical fiber position adjusting method according to still another embodiment of the present invention.
FIG. 14 is a sectional view showing a structure of an optical device according to still another embodiment of the present invention.
FIG. 15 is a sectional view showing the structure of an optical device according to still another embodiment of the present invention.
[Explanation of symbols]
1 Optical device
2 Optical waveguide
3 Mounting part
4 Optical fiber (optical fiber groove)
5 Optical fiber core
6 adhesive
61-67 adhesive
21-35 Optical waveguide for curing adhesive, optical waveguide for adjusting optical fiber position

Claims (13)

An optical device and an optical fiber are formed by applying and curing a photocurable adhesive or a thermosetting adhesive between an optical device having an optical waveguide which is a component of an optical circuit and an optical fiber for transmitting light. In the method of combining
Inserting an optical fiber into an optical fiber mounting portion of the optical device;
Applying an adhesive to the mounting portion into which the optical fiber is inserted,
Adjusting the position of the optical fiber. 2. The method of connecting an optical device and an optical fiber according to claim 1, wherein when an optical curing type adhesive is used as the optical fiber position fixing adhesive, an optical waveguide for adhesive curing is formed in the optical device. . 3. The optical device according to claim 2, wherein an optical device having a plurality of optical fiber position adjusting optical waveguides provided at symmetrical positions separated from the optical waveguides constituting the optical circuit by at least the radius of the optical fiber is used. Join method. 4. The method for coupling an optical device and an optical fiber according to claim 3, wherein an optical device provided with optical fiber position adjusting optical waveguides having different cross-sectional areas is used. 4. The method for coupling an optical device and an optical fiber according to claim 3, wherein an optical device provided with an optical fiber position adjusting optical waveguide having an end surface facing the optical fiber side surface is used. 4. An optical device according to claim 3, wherein an optical device is provided with a plurality of optical fiber position adjusting optical waveguides at symmetric positions separated from the optical waveguides constituting the optical circuit by substantially the radius of the optical fiber. How to join. 7. The optical fiber according to claim 6, wherein an optical waveguide for adjusting the position of the optical fiber to be irradiated with light is selected by detecting reflected light of the light incident on the optical fiber position adjusting optical waveguide at the end face of the optical fiber. Device and optical fiber connection method. Using a photo-curing adhesive prepared by mixing a plurality of types of polymerization initiators having different wavelength characteristics, and changing the wavelength of light incident on the optical fiber position adjusting optical waveguide, the curing shrinkage of the photo-curing adhesive can be reduced. 3. The method according to claim 2, wherein the optical device is controlled. 9. The method for coupling an optical device and an optical fiber according to claim 8, wherein the concentrations of the plural kinds of polymerization initiators are different. At least in the vertical and horizontal directions between the optical device and the optical fiber, after applying a photocurable resin having a different curing wavelength in each direction, the light of the curing wavelength of the resin applied on the opposite side to the misalignment direction is applied to the optical fiber. 3. The method for coupling an optical device and an optical fiber according to claim 2, wherein the irradiation is performed via an optical waveguide for position adjustment. A light-curing adhesive that has a light transmittance approximately equal to that of the optical waveguide of the optical device when cured is used for the end face of the optical fiber, and an adhesive force equal to or higher than the adhesive strength of the light-curing adhesive used for the end face is used for the side face of the optical fiber. 3. The method according to claim 2, wherein an adhesive having a force is used. In the step of inserting the optical fiber into the optical device, the position of the optical fiber is roughly determined by inserting the optical fiber having a convex end surface into the optical device having the concave portion on the surface facing the optical fiber end surface and matching the concave and convex. 3. The method for coupling an optical device and an optical fiber according to claim 2, wherein: An optical device with an optical fiber, manufactured by the method for coupling an optical device and an optical fiber according to claim 1.

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