JP2005275049A - Method for forming microlens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a microlens having a spherical part with predetermined radius of curvature is easily and surely formed to a member for optical transmission having a core part of an optical fiber, etc. <P>SOLUTION: The method for forming the microlens includes (A) a process for making drops 4 of liquid photocuring resin composition adhere to an upper edge of the optical fiber 5 using the other optical fiber 1 at a state that the edge of the optical fiber 5 is turned upward and forming hemispherical drops having outer diameter larger than that of the core part of the optical fiber 5 on the upper edge of the optical fiber 5 and (B) a process for irradiating the liquid drops with ultraviolet rays 12 through the core part of the optical fiber 5 and forming the microlens 14 including a part of the outer surface of the drops as contours. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a microlens for reducing connection loss, which is provided on an end face of an optical transmission member such as an optical fiber, an optical fiber array, or an optical waveguide.

Optical fiber communication is a basic technology that supports high-speed and high-speed communication and supports the modern information society. Optical modules used in optical fiber communications (specifically, optical transceiver modules such as semiconductor lasers and photodiodes) are required to be reduced in size, thickness, and cost.
Under such circumstances, reducing the connection loss at the connection between the optical fiber and the optical module is an issue. As a method for reducing this connection loss, a method of forming a microlens on the end face of an optical fiber is conventionally known.
As an example, an optical fiber with a lens in which a lens made of a photocurable resin having an outer diameter smaller than the outer diameter of an optical fiber cladding is formed on an end surface of the optical fiber has been proposed (Patent Document 1). ).
In this optical fiber with a lens, after a cured resin is formed on the lower end of the optical fiber, an uncured resin is attached to the lower surface of the cured resin, and the uncured resin is cured with a curing light to form a spherical shape. It is manufactured by forming a lens.
As another example, a core-diameter-enlarged optical fiber with a lens is proposed in which a convex lens is attached to the end face of a core-diameter-enhanced single-mode optical fiber whose core diameter at the end of the single-mode optical fiber is increased as it approaches the end face. (Patent Document 2).
In this core diameter-enlarged optical fiber with a lens, the end of the core diameter-enlarged single mode optical fiber is immersed in a liquid transparent material in such a posture that the optical axis is almost vertical, pulled up in that posture, and attached to the end surface. It is manufactured by curing the drips to form a hemispherical lens on the end face of the optical fiber.
Japanese Patent Laid-Open No. 10-221547 Japanese Patent Laid-Open No. 7-29479

In the conventional technology described above, the size of the lens diameter is determined by the diameter of the end face of the optical fiber (or the bottom surface of the cured resin formed on the end face), and it is difficult to adjust to various dimensions.
In the above-described conventional technology, the uncured resin for forming the lens is attached with the end face of the optical fiber facing downward. Therefore, the uncured resin adheres to and is held on the lower end surface of the optical fiber by surface tension that balances with gravity. In this case, the contour of the uncured resin is unstable and easily changes, and it is difficult to maintain a spherical portion having a predetermined radius of curvature.
Accordingly, an object of the present invention is to easily and surely form a microlens having a spherical surface with a predetermined radius of curvature that can increase the light transmission efficiency for an optical transmission member having a core such as an optical fiber. It is to provide a method that can do this.

As a result of intensive studies to solve the above problems, the present inventor has obtained a liquid light so that the core portion on the end face of the optical transmission member such as an optical fiber has an outer diameter larger than the outer diameter of the core portion. After the droplets of the curable resin composition are attached, the droplets are irradiated with light to photocure a predetermined region of the droplets, thereby increasing the light transmission efficiency. The present inventors have found that a microlens having a curved surface with a radius of curvature can be formed.
That is, the method for forming a microlens of the present invention is a method for forming a microlens with respect to an end surface of an optical transmission member having at least one core part, and (A) the above-described end surface of the optical transmission member A step of attaching droplets of a liquid photocurable resin composition to each of the core portions so as to have an outer diameter larger than the outer diameter of the core portion; and (B) the photocurable resin composition The droplet is irradiated with light having a wavelength capable of curing the photocurable resin composition, so that at least a part of the droplet is photocured, and at least a part of the contour of the outer surface of the droplet is formed. Forming a microlens to be included as an outer surface.

In the step (A), it is preferable that the droplets are attached in a state where the end face of the optical transmission member faces upward.
It is preferable that the adhesion amount of the droplets in the step (A) is determined so that the outer diameter of the microlens is 20 μm or more.
As an example of the method for attaching the droplets in the step (A), there is a method using an optical fiber having a liquid photocurable resin composition attached to the lower end.
In this case, the optical fiber and the optical transmission member can be aligned by emitting light of a wavelength that does not cure the liquid photocurable resin composition from the optical fiber.
As another example of the method for depositing droplets in the step (A), there is a method using a liquid ejecting means capable of ejecting a droplet of a predetermined liquid amount downward.
As an example of the photocuring method in the step (B), there is a method of emitting light having a wavelength capable of curing the liquid photocurable resin composition from the core portion of the optical transmission member.
As another example of the photocuring method in the step (B), the optical fiber is opposed to the core portion of the optical transmission member to which the liquid droplets adhere so that the optical axis is substantially coincident with the core portion. And a method of emitting light having a wavelength capable of curing the liquid photocurable resin composition from the optical fiber.
Examples of the optical transmission member that is an object of the method of the present invention include an optical fiber, an optical fiber array, and an optical waveguide.

According to the method for forming a microlens of the present invention, a microlens having a spherical surface with a predetermined radius of curvature can be easily and reliably formed on an optical transmission member having a core such as an optical fiber.
Further, since the microlens formed by the method of the present invention has a spherical surface portion (outer surface) having a predetermined radius of curvature, an optical transmission member such as an optical fiber, an optical module such as a semiconductor laser, or other optical transmission When connecting the working member, it is possible to reduce the connection loss and increase the tolerance for the shaft misalignment.
In particular, since the microlens formed by the method of the present invention has an outer surface having a radius of curvature larger than the outer diameter of the core portion, the distance (usually several) between the optical transmission member and the optical module. ([mu] m to several hundreds of [mu] m), and the light transmission efficiency between the optical transmission member and the optical module can be increased.
Further, according to the method for forming a microlens of the present invention, the microlens can be formed directly on the end face of the optical transmission member such as an optical fiber. Compared with a method in which a synthetic resin molded body is interposed, a microlens can be formed efficiently.
Furthermore, since the method for forming a microlens of the present invention does not include steps such as heating and melting, the microlens can be formed in a short time using simple equipment.

  The method for forming a microlens according to the present invention is a method for forming a microlens with respect to an end surface of an optical transmission member having at least one or more core portions, and (A) each of the core portions on the end surface of the optical transmission member. On the other hand, a step of adhering a liquid photocurable resin composition droplet so as to have an outer diameter larger than the outer diameter of the core portion, and (B) the photocurable resin composition droplet, Irradiating with light having a wavelength capable of curing the photocurable resin composition, photocuring at least a part of the droplets, and having at least a part of the contour of the outer surface of the droplets as an outer surface Forming a lens.

[Step A]
The step (A) is a step of attaching a liquid photocurable resin composition droplet to each of the core portions on the end face of the optical transmission member so as to have an outer diameter larger than the outer diameter of the core portion. It is.
Here, examples of the optical transmission member are not particularly limited as long as they have an axial core portion that is a light transmission path, and examples thereof include an optical fiber, an optical fiber array, and an optical waveguide. It is done.
The optical fiber is a member composed of an axial core portion and a clad portion that is coated around the core portion. In the optical fiber array, a plurality of optical fiber parts including an axial core part and a clad part coated around the core part are formed by using a suitable matrix material. It is a member (in other words, a member in which a plurality of optical fibers are integrally arranged in parallel) that are arranged so as to be parallel to each other at intervals.

In the step (A), the optical transmission member is preferably such that the end surface is directed upward, that is, the surface on which the liquid photocurable resin composition droplets are to be adhered is a substantially horizontal upper surface. Placed in. In this case, liquid droplets of the photocurable resin composition are attached to each of the core portions of the optical transmission member with the end face of the optical transmission member facing upward. Thereby, the adhesion amount of the droplet can be adjusted more easily, and the shape of the curved surface portion of the outer surface of the droplet can be made more suitable.
The droplets of the photocurable resin composition must be attached so as to have an outer diameter larger than the outer diameter of the core portion. When the outer diameter of the droplet is equal to or smaller than the outer diameter of the core portion, the radius of curvature of the microlens formed by curing the droplet is reduced, and light is transmitted at the connection portion between the optical transmission member and the optical module. It becomes difficult to increase efficiency.
Note that the term “droplet outer diameter” means the outer diameter of the droplet-attached portion on the end face of the optical transmission member (however, if it is not circular, the maximum dimension).
In the present invention, the outer diameter of the droplet is preferably 20 μm or more, more preferably 20 to 130 μm, still more preferably 40 to 120 μm, and particularly preferably 60 to 110 μm.
If the outer diameter of the droplet is too large (for example, 200 μm or more), the radius of curvature of the microlens formed by the curing of the droplet becomes excessively large, and the transmission efficiency may decrease.

The kind of the photocurable resin composition used in the present invention is not particularly limited. For example, a composition containing a photopolymerizable monomer such as an acrylic monomer or an epoxy monomer, a photopolymerization initiator, and the like. Can be mentioned.
Here, examples of the acrylic monomer include (meth) acrylate having two (meth) acryloyl groups in the molecule, (meth) acrylate having one (meth) acryloyl group in the molecule, Examples include (meth) acrylates having three or more (meth) acryloyl groups.
Among these, examples of (meth) acrylates having two (meth) acryloyl groups in the molecule include ethylene oxide-added bisphenol A-type di (meth) acrylate, ethylene oxide-added tetrabromobisphenol A-type di (meth) acrylate, and propylene oxide. Bisphenol-containing di (meth) acrylates such as addition bisphenol A type di (meth) acrylate, propylene oxide addition tetrabromobisphenol A type di (meth) acrylate, alkyldiol diacrylates such as 1,4-butanediol diacrylate, And polyalkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate. In addition, since the (meth) acrylate which has two (meth) acryloyl groups in a molecule | numerator can improve heat resistance etc., it is used preferably.
Examples of (meth) acrylates having one (meth) acryloyl group in the molecule include phenoxy group-containing (meth) acrylates such as phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) ) Acrylate, ethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, and the like.
Examples of (meth) acrylate having three or more (meth) acryloyl groups in the molecule include trimethylolpropane tri (meth) acrylate.

As the photopolymerization initiator used in the present invention, a compound (photoradical polymerization initiator) that generates active radical species by irradiation with active energy rays such as ultraviolet rays is suitably used.
Examples of photopolymerization initiators include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2,2-dimethoxy 2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy- -Methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1- ON, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, and the like.
The blending ratio of the photopolymerization initiator in the photocurable resin composition used in the present invention is preferably 0.01 to 10% by mass, more preferably 0.1 to 7% by mass, and particularly preferably 0.5 to 5%. % By mass. When the blending ratio is less than 0.01% by mass, problems such as a decrease in the curing rate of the composition may occur. When the blending ratio exceeds 10% by mass, problems such as deterioration of transmission characteristics may occur.
Examples of other components of the photocurable resin composition include solvents, photosensitizers, antioxidants, ultraviolet absorbers, light stabilizers, silane coupling agents, coating surface improvers, thermal polymerization inhibitors, and leveling. Agents, surfactants and the like. These components are blended in appropriate amounts as necessary.

As a method of attaching the droplets in the step (A), for example, any of the following methods (a) and (b) can be employed.
(A) Method of using optical fiber for attaching droplets First, after immersing the lower end of an optical fiber for attaching droplets having a predetermined outer diameter in a liquid photocurable resin composition in a liquid tank Then, the optical fiber for droplet adhesion is pulled up. Next, the droplet adhering optical fiber is moved above the optical transmission member disposed with the end surface including the core portion facing upward, and the droplet adhering to the lower end of the droplet adhering optical fiber. Is attached in contact with the vicinity of the core portion of the optical transmission member.
At this time, light having a wavelength that does not cure the photocurable resin composition is emitted from the core portion of the optical fiber for droplet adhesion toward the core portion of the optical transmission member, and the position of the optical fiber for droplet adhesion is determined. While adjusting, look for the point where the intensity of the light incident on the optical transmission member is maximized, thereby matching the optimal position of the optical fiber for droplet adhesion (ie, the axis of the core of the optical transmission member) It is preferable to determine the position of the liquid transmission member and to attach the droplet to the optical transmission member at that position. In this case, the adhering droplet is formed in a substantially hemispherical shape centering on the core portion.

(B) Method Using Liquid Ejecting Unit First, an optical transmission member is arranged at a predetermined position with the end surface including the core portion facing upward. Next, the ejection port of the liquid ejection means capable of ejecting a predetermined amount of liquid droplets downward is moved above the optical transmission member by automatic control. And the droplet of a photocurable resin composition is dropped from the discharge outlet of a liquid discharge means, and a droplet is made to adhere to the core part of the member for optical transmission.
Here, the liquid ejecting means is not particularly limited as long as it can eject an appropriate amount of liquid droplets to form a microlens on the end face of the optical fiber. For example, an ink jet apparatus or a dispenser apparatus may be used. Etc. When the liquid volume of the liquid droplet is small, the liquid droplet ejection may be repeated a plurality of times until the liquid volume reaches a predetermined liquid volume (total volume) with respect to the core portion of the optical transmission member.

[Step B]
In the step (B), light having a wavelength capable of curing the photocurable resin composition is applied to the droplets of the photocurable resin composition attached to the optical transmission member in the above step (A). Then, at least a part of the droplet is photocured to form a microlens including at least a part of the contour of the outer surface of the droplet as the outer surface.
Here, as the light irradiation method, (a) a method of emitting light having a wavelength for curing the photocurable resin composition adhering to the core portion as droplets from the core portion of the optical transmission member, (B) After the optical fiber is disposed above the optical transmission member so that the optical axis coincides with the core portion of the optical transmission member to which the liquid droplets are attached. And a method of emitting light having a wavelength capable of curing the photocurable resin composition from the core of the optical fiber toward the core of the optical transmission member.
The outer surface having a wider area than the projected portion of the core portion of the light transmission member on the outer surface of the droplet of the light transmission member (see reference numeral S in FIG. 2) is irradiated with light. This is performed until the contour of the cured product (microlens) is formed. In order to form such a contour of the cured product, it is necessary to adjust the intensity of irradiation light and the irradiation time to a certain level or more. For example, when light is emitted from the core portion of the optical transmission member (in the case of the method (a) described above), a cured product (microlens) having a wide curved portion is formed by irradiating with ultraviolet rays for 5 minutes or more. be able to.
After the formation of the microlens, if the uncured photocurable resin composition is removed using a solvent such as acetone or ethanol, an optical transmission member having the microlens is completed.

The outer diameter of the microlens is preferably 20 μm or more, more preferably 20 to 120 μm, still more preferably 30 to 110 μm, and particularly preferably 40 to 100 μm.
When the outer diameter of the microlens is too large (for example, 150 μm or more), the radius of curvature of the curved surface portion tends to increase, and as a result, the focal length becomes too large and transmission efficiency decreases. Sometimes.
The “outer diameter of the microlens” is defined as the maximum dimension of the projected portion of the microlens with respect to the end face of the optical transmission member. For example, when the microlens is hemispherical, it means the diameter of the hemispherical.
The radius of curvature of the curved surface portion of the outer surface of the microlens is preferably 20 to 100 μm.
The focal length of the microlens is preferably 20 μm or more, more preferably 20 to 100 μm.
An optical transmission member having a microlens manufactured by the method of the present invention is connected to an optical module such as a semiconductor laser or a photodiode, or another optical transmission member (optical fiber, optical fiber array, optical waveguide, etc.). Used.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing an example of a method for forming a microlens of the present invention for an optical fiber, and FIG. 2 shows an example of a method for curing a photocurable resin composition in (c) of FIG. FIG. 3 is a flowchart showing another example of the photocurable resin composition curing method in FIG. 1C, and FIG. 4 is a diagram of the microlens of the present invention for an optical fiber array. It is a flowchart which shows an example of the formation method.

[A. When the optical fiber is a microlens attachment object]
In FIG. 1, after the lower end of the optical fiber 1 for adhering droplets is immersed in the photocurable resin composition 3 in the liquid tank 2, the optical fiber 1 is pulled up ((a) in FIG. 1). Next, an optical fiber 5 (having the same diameter as the optical fiber 1) for forming a microlens in which the optical fiber 1 having the droplet 4 of the photocurable resin composition 3 attached to the lower end is disposed so as to extend in the vertical direction. Then, the lower end of the optical fiber 1 is brought close to the upper end of the optical fiber 5 ((b) in FIG. 1), and the droplet 4 is attached to the optical fiber 5. The liquid droplet 6 adhering to the upper end surface of the optical fiber 5 has a slightly smaller liquid volume than the liquid droplet 4 and has an outer diameter larger than the outer diameter of the core portion 10 of the optical fiber 5 as shown in FIG. And has a substantially hemispherical shape having an outer diameter equal to or smaller than the outer diameter of the cladding portion 11 of the optical fiber (also the outer diameter of the optical fiber 5).
After that, as shown in FIG. 2B, light 12 having a wavelength capable of curing the photocurable resin composition at the end of the optical fiber 5 opposite to the end to which the droplet 6 is attached. (For example, ultraviolet rays) are incident, and the ultraviolet rays 12 are emitted from the end portion to which the droplets 6 are attached, whereby the droplets 6 made of the photocurable resin composition are gradually cured to obtain a cured product 13. To form. In addition, what is necessary is just to adjust the intensity | strength of an ultraviolet-ray so that the power in an output port may be about 50-100 microwatts, for example.
As shown in FIG. 2C, the emission of the ultraviolet rays 12 includes at least a region wider than the projected portion of the core 10 on the outer surface of the droplet 6 (reference S in FIG. 2A). This is performed until a cured product including an outline (outer surface) is formed. The irradiation time is, for example, 5 to 10 minutes. When the intensity of light irradiation is small (for example, 1 μW or less) or when the irradiation time is short (for example, 3 minutes or less), a cured product (microlens) having at least a part of the outer surface of the droplet 6 as an outline. ) Is difficult to form.
If the uncured photocurable resin composition 15 is removed by using acetone or the like after irradiation with ultraviolet rays, the optical fiber 5 having the microlens 14 at the end can be obtained.

In addition, as shown in FIG. 3, you may perform irradiation of an ultraviolet-ray using another optical fiber.
In FIG. 3, the optical fiber 20 is disposed above the optical fiber 5, and light having a wavelength that does not cure the photocurable resin composition (for example, light having a wavelength of 1,550 nm) is transferred from the optical fiber 20 to the optical fiber 5. The position where the intensity of the light emitted and transmitted to the optical fiber 5 is maximized is examined and aligned ((a) in FIG. 3). The optical fiber 20 includes a core portion 21 and a cladding portion 22.
Thereafter, light 23 (for example, ultraviolet rays) having a wavelength capable of curing the photocurable resin composition is emitted from the core portion 21 of the optical fiber 20 toward the core portion 10 of the optical fiber 5, so that the photocurable resin composition is obtained. The liquid droplet 6 made of a material is gradually cured to form a cured product 24. When the contact area between the lower end of the cured product 24 and the optical fiber 5 becomes sufficiently large, the irradiation of the ultraviolet rays 23 is stopped, and the uncured photocurable resin composition 26 is removed. Is obtained at the end.

[B. When the optical fiber array is a microlens attachment target]
In FIG. 4, the lower end of the optical fiber 1 for droplet adhesion is immersed in the photocurable resin composition 3 in the liquid tank 2, and then the optical fiber 1 is pulled up ((a) in FIG. 4). Next, the optical fiber 1 with the droplet 4 of the photocurable resin composition 3 attached to the lower end is disposed above the core portion of the optical fiber array 30 (an assembly in which a plurality of optical fiber portions 31 are arranged in parallel). Light having a wavelength that does not cure the photocurable resin composition 3 with a distance (gap) of about 100 μm being moved ((b) in FIG. 4) (for example, light having a wavelength of 1,550 nm). Is applied to the core portion of the optical fiber array 30 for alignment.
Next, the optical fiber 1 is lowered, and the droplet 4 attached to the lower end of the optical fiber 1 is attached to the core portion of the optical fiber array 30 ((c) in FIG. 4).
The droplet 32 attached to the core portion of the optical fiber array 30 has an outer diameter larger than the outer diameter of the core portion of the optical fiber portion 31, and the outer diameter of the cladding portion of the optical fiber portion 31 (in FIG. 4). Is formed in a substantially hemispherical shape having an outer diameter equal to or smaller than that.
Thereafter, an optical fiber 33 for light irradiation (having the same diameter as that of the optical fiber portion 31) is prepared, aligned in the same manner as described above, and then separated by a distance (gap) of about 500 μm. A cured product (microlens) is formed by irradiating light 33 (for example, ultraviolet rays) having a wavelength capable of curing the photocurable resin composition from the core portion toward the core portion of the optical fiber array 30. After the above procedure is performed on each of the core portions of the optical fiber array 30 in the same manner, if the uncured photocurable resin composition is removed using acetone or the like, a microlens 34 is formed on each of the core portions. The optical fiber array 31 to which is attached is obtained.

Examples of the present invention will be described below.
[Preparation of Photocurable Resin Composition]
A mixture of 98% by weight of ethylene oxide-added bisphenol A type di (meth) acrylate and 2% by weight of a radical polymerization initiator (IRGACURE 819, manufactured by Ciba Specialty Chemicals) was prepared.
[Example 1]
As shown in FIG. 1, the lower end of the optical fiber 1 (outer diameter: 125 μm, core part diameter: 10 μm) is immersed in the photocurable resin composition 3 in the liquid tank 2, and then pulled up to form a photocurable resin. An optical fiber 1 having a droplet of the composition 3 attached to the lower end was obtained. Next, the droplet of the optical fiber 1 was attached to the upper end face of the optical fiber 5 (outer diameter: 125 μm, core portion diameter: 10 μm). Then, a laser beam of 405 nm is introduced into the other end of the optical fiber 5, and the droplet on the optical fiber 5 is irradiated with light while adjusting the output power of the laser light source so that the power at the upper end of the optical fiber 5 becomes 75 μW. did. After performing light irradiation for 6 minutes, the uncured photocurable resin composition was washed away with acetone to obtain an optical fiber having microlenses 14. The microlens 14 was hemispherical with an outer diameter of 80 μm.

[Example 2]
As shown in FIG. 4, the lower end of the optical fiber 1 (outer diameter: 125 μm, core part diameter: 10 μm) is immersed in the photocurable resin composition 3 in the liquid tank 2, and then pulled up to form a photocurable resin. An optical fiber 1 having a droplet 4 of the composition 3 attached to the lower end was obtained. Next, the optical fiber 1 is moved above the core portion of the optical fiber array 30 (an assembly in which a plurality of optical fiber portions 31 having an outer diameter of 125 μm and a core portion diameter of 10 μm are arranged in parallel). ((B) in FIG. 4), with a distance (gap) of 100 μm separated, light having a wavelength of 1,550 nm was applied to the core portion of the optical fiber array 30 for alignment.
Next, the optical fiber 1 was lowered, and the droplet 4 attached to the lower end of the optical fiber 1 was attached to the core portion of the optical fiber array 30 ((c) in FIG. 4).
Thereafter, an optical fiber 33 for light irradiation (outer diameter: 125 μm, core diameter: 10 μm) is prepared, aligned in the same manner as described above, and then separated by a distance (gap) of 500 μm. A cured product (microlens) was formed by irradiating ultraviolet rays having a wavelength of 405 nm from the 33 core portions toward the core portion of the optical fiber array 30. At this time, the intensity of the laser beam was determined so that the power at the lower end of the optical fiber 33 was 1 μW.
After the above procedure is similarly performed on each of the core portions of the optical fiber array 30, the uncured photocurable resin composition is removed using acetone, and the microlenses 34 are attached to each of the core portions. An optical fiber array 31 was obtained. The microlens 14 was hemispherical with an outer diameter of 90 μm.

It is a flowchart which shows an example of the formation method of the micro lens of this invention which made optical fiber object. It is a flowchart which shows an example of the hardening method of the photocurable resin composition in (c) in FIG. It is a flowchart which shows the other example of the hardening method of the photocurable resin composition in (c) in FIG. It is a flowchart which shows an example of the formation method of the micro lens of this invention which made optical fiber array object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,5,20,33 Optical fiber 2 Liquid tank 3 Photocurable resin composition 4,6,32 Droplet 10,21 Core part 11,22 Clad part 12,23 The wavelength which can harden a photocurable resin composition Light (ultraviolet light)
13, 24 Cured product 14, 25, 34 Microlens 15, 26 Uncured photocurable resin composition 30 Optical fiber array 31 Optical fiber portion

Claims (10)

A method for forming a microlens on an end face of an optical transmission member having at least one core part,
(A) The process of making the droplet of a liquid photocurable resin composition adhere to each of the said core part in the said end surface of the said optical transmission member so that it may have an outer diameter larger than the outer diameter of the said core part. When,
(B) The liquid droplets of the photocurable resin composition are irradiated with light having a wavelength capable of curing the photocurable resin composition, so that at least a part of the liquid droplets is photocured, and the liquid Forming a microlens including at least a part of the contour of the outer surface of the droplet as an outer surface.   The method of forming a microlens according to claim 1, wherein in the step (A), the liquid droplets are attached in a state where the end face of the optical transmission member is directed upward.   The method for forming a microlens according to claim 1 or 2, wherein, in the step (A), an adhesion amount of droplets is determined so that an outer diameter of the microlens is 20 μm or more.   The formation of the microlens according to any one of claims 1 to 3, wherein droplets are attached in the step (A) using an optical fiber having the liquid photocurable resin composition attached to a lower end. Method.   After aligning the optical fiber and the optical transmission member by emitting light of a wavelength that does not cure the liquid photocurable resin composition from the optical fiber, the droplets adhere to each other. The method of forming a microlens according to claim 4 to be performed.   The method for forming a microlens according to any one of claims 1 to 3, wherein the droplet is attached in the step (A) using a liquid discharge means capable of discharging a droplet of a predetermined liquid amount downward. .   The light curing in the step (B) is performed by emitting light having a wavelength capable of curing the liquid photocurable resin composition from the core portion of the optical transmission member. The method for forming a microlens according to any one of the above.   An optical fiber is disposed opposite to the core portion of the optical transmission member to which the droplet is attached so that the optical axis is substantially coincident with the core portion, and then the liquid is removed from the optical fiber. The method for forming a microlens according to any one of claims 1 to 6, wherein photocuring in the step (B) is performed by emitting light having a wavelength capable of curing the photocurable resin composition.   The method for forming a microlens according to claim 1, wherein the optical transmission member is an optical fiber. The method for forming a microlens according to claim 1, wherein the optical transmission member is an optical fiber array.

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