JPH10221547A - Optical fiber with lens and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize the curvature radius of a lens at low price and improve total efficiency of the light by attaching the lens, which has the outermost diameter smaller than the outer diameter of a clad of an optical fiber and is formed of an optically hardening resin, to an end face of the optical fiber. SOLUTION: An end part of an optical fiber 1 is lowered (a) into a tank 21 filled with optically hardening resin 2. Secondly, the end part of the optical fiber 1 is dipped therein while holding a fixed interval h1 from the bottom of the tank 21. A hardening light 11 for the optically hardening resin 2 is guided from the undipped end face of the optical fiber 1 to a core 1a and the optically hardening resin 12 is hardened (b) by an emitting light 12 from the dipped end face of the optical fiber 1 in such a state as setting the core 1a as its center. When the optical fiber 1 is drawn up a fixed time later, the hardened resin 3 is formed in the end of the optical fiber 1 and the unhardened resin 4 is stuck (c) to its tip by the quantity of balancing between the surface tension of the resin and the gravity. Later, a hardening light 13 is irradiated so as to hardened the unhardened resin 4 and then a spherical lens is formed (d).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical fiber with a lens and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as one method of coupling light emitted from a semiconductor laser, a light emitting diode, an optical waveguide, or the like to an optical fiber so as to reduce light loss, an effect of a lens is applied to the tip of the optical fiber. A method of processing the tip into a hemispherical shape or a conical shape is used so as to have the tip. For example,
As in the case of "optical fiber (Japanese Patent Application Laid-Open No. 58-123512)", the tip of the optical fiber is processed by mechanical polishing so as to be conical, and the portion is heated and melted by arc discharge or the like, and the tip is rounded. Smooth. Further, as an example of adding a substance other than the optical fiber to the tip of the optical fiber, there is "Optical fiber with enlarged core diameter with lens and method of manufacturing the same (Japanese Patent Application Laid-Open No. 7-294779)". As shown in FIG. 7, an optical fiber 1 having a core 1a and a clad 1b
Is moved down to the tank 21 filled with the photo-curable resin 2 by the optical fiber lowering operation 47 (a).
The end of the optical fiber 1 is placed inside (b), and after a certain time elapses, the uncured resin 4 adheres to the end of the optical fiber 1 when pulled up by the optical fiber raising operation 48 (c). The uncured resin 4 is cured by irradiating light 13 to form a spherical lens.

[0003]

However, the above-mentioned manufacturing method requires two-stage work because it is processed by mechanical polishing and then heated and melted by arc discharge or the like.
There is a problem that the cost of the finished product is increased accordingly. In addition, there is also a problem that a plurality of optical fibers arranged in an array cannot be machined because a plurality of optical fibers cannot be mechanically polished at the same time.

[0004] In the other manufacturing method described above,
As shown in FIG. 8, there is a problem in the coupling efficiency when optically coupling with the semiconductor laser 25. Since the radius of curvature R1 of the cured resin 30 for the lens effect formed on the entire front end of the optical fiber 1 tends to be relatively large, only a part of the laser emission light 25a having a spread from the semiconductor laser 25 is used.
A large amount of light is not guided to the core 1a and escapes to the cladding 1b, and the light condensing action of the lens is small, so that it is difficult to increase the optical coupling efficiency.

An object of the present invention is to provide an optical fiber with a lens or an optical fiber array in which a plurality of optical fibers are arranged at a low cost and have a small radius of curvature of a lens and a high light coupling efficiency, and a method of manufacturing the same.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for attaching a lens formed of a photocurable resin with an outermost diameter smaller than the outer diameter of the cladding of an optical fiber to an end face of the optical fiber. An optical fiber with a lens is provided.

According to another aspect of the present invention, an end face of an optical fiber has a light guide portion having an outermost diameter smaller than the outer diameter of the clad of the optical fiber, and a lens is attached to the end face of the light guide portion. An optical fiber with a lens is provided.

According to another aspect of the present invention, there is provided an optical fiber with a lens, wherein the light guide and the lens are formed of a photocurable resin.

According to another aspect of the present invention, a plurality of optical fibers each having a lens having an outermost diameter smaller than the outer diameter of the cladding of the optical fiber attached to the end face of the optical fiber are arranged. An optical fiber array with a lens is provided.

According to the present invention, a photocurable resin is attached and cured to an optical fiber whose end face has only been cut, and then the uncured portion attached by surface tension is cured, thereby reducing the radius of curvature of the lens at low cost. It is possible to form a lens having a small light coupling efficiency. Further, since the optical fiber array can be formed on a plurality of optical fibers at the same time, an optical fiber array with a lens can be easily formed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a first embodiment of the method for manufacturing an optical fiber according to the present invention. Core 1 that guides light
The end of the optical fiber 1 having a structure in which a is slightly surrounded by the cladding 1b having a low refractive index is lowered by the optical fiber lowering operation 41 into the tank 21 filled with the photocurable resin 2 (a).
Next, the end of the optical fiber 1 is immersed in the photocurable resin 2 while maintaining a constant interval h1 with the bottom of the tank 21. The curing light 11 of the photocurable resin 2 is guided to the core 1a from the end face of the optical fiber 1 where the liquid is not immersed, and the light is emitted from the end face of the optical fiber 1 in the immersion liquid so as to center around the core 1a. 21
Is cured in the photocurable resin 2 in the space at the constant distance h1 from the bottom surface of (b). After a certain period of time, when the optical fiber 1 is pulled up by the optical fiber raising operation 42, the optical fiber 1
The cured resin 3 is formed at the end of the uncured resin 3, and the uncured resin 4 adheres to the tip of the cured resin 3 by an amount that balances the surface tension of the resin with the gravity (c). Thereafter, the uncured resin 4 is cured by irradiating curing light 13 to form a spherical lens (d).

FIG. 2 is a diagram illustrating a second embodiment of the method for manufacturing an optical fiber according to the present invention. The end portion of the optical fiber 1 is lowered by the optical fiber lowering operation 43 to be slightly below the liquid level of the tank 22 filled with the photocurable resin 2. On the other hand, tank 2
The stage surface 24 set parallel to the liquid surface in 2 is positioned using the stage vertical shaft 23 so as not to come out of the liquid surface (a). Next, while keeping the distance between the end of the optical fiber 1 and the liquid surface of the photocurable resin 2 at h2, the light 11 for curing the photocurable resin 2 is guided to the core 1a from the opposite end surface of the optical fiber 1. The optical fiber 1 emits light 12 emitted from the liquid-side end face of the optical fiber 1. The photocurable resin 2 in the space of the space h3 between the stage surface 24 and the liquid surface with the core 1a as the center is cured. As the curing progresses, the stage vertical shaft 23 is lowered at a fixed rate by the stage lowering operation 44 to increase the thickness h3 and increase the thickness of the cured resin 5 (b). Next, when the cured resin 5 has a predetermined thickness, the curing light 11 is temporarily stopped, and then the stage vertical shaft 23 is lowered, so that the uncured photocurable resin 2 is thinned on the cured resin 5. The stage vertical shaft 23 is stopped so as to cover the stage. The optical fiber 1 is moved by the optical fiber lowering operation 45.
Is lowered by h2 so as to come into contact with the liquid surface, and then the curing light 11
Is again emitted to cure the photocurable resin 2 between the cured resin 5 and the end face of the optical fiber, and the cured resin 5 is connected to the end face of the optical fiber (c). When the optical fiber 1 is pulled up after a certain period of time, the cured resin 5 is formed at the end of the optical fiber 1, and the uncured resin 6 adheres to the tip of the optical fiber 1 in an amount that balances the surface tension of the resin with the gravity. Curing light 13
To cure the uncured resin 6 to form a spherical lens (d).

The case where the optical fiber with a lens formed by the above two methods is optically coupled to a semiconductor laser will be described with reference to FIG. The radius of curvature of the cured resin 26 formed at the tip of the optical fiber 1 can be relatively small,
Further, since the length L of the portion for guiding the light to the core 1a can be set to an arbitrary length, most of the laser emission light 25a having a spread from the semiconductor laser 25 is guided to the core 1a of the optical fiber 1, and the cladding 1b The amount of light that escapes is reduced, the light condensing action of the lens is large, and the optical coupling efficiency is easily increased.

FIG. 4 shows another embodiment for reducing the radius of curvature. The end of the optical fiber 1 having the core 1a and the clad 1b is lowered to a tank 21 filled with the photo-curable resin 2,
In a state where the end of the optical fiber 1 is attached to the photocurable resin 2, the curing incident light 11 is guided to the core 1 a and emitted from the core 1 a at the tip of the optical fiber 1. 2
Is cured to form a cured resin 32 (a). After the elapse of a predetermined time, the cured resin 32 can be attached to the end of the optical fiber 1 by pulling it up by the optical fiber raising operation 49 (b). Since the shape of the cured resin 32 becomes a shape (generally, a Gaussian distribution) corresponding to the light intensity distribution of the curing light emitted from the core 1a, the radius of curvature R3 at the tip can be made relatively small. In order to smooth the surface shape of the cured resin, the uncured resin attached to the end of the cured resin 32 is cured by irradiating curing light to form a lens.

Further, as shown in FIG. 5, as another method for reducing the radius of curvature of the lens effect portion and increasing the space between the lens and the semiconductor laser to increase the optical coupling efficiency, a tapered portion 1c at the tip of the optical fiber 1 is used. Is provided, and the cured resin 31 is adhered and cured in the same manner as in the above-described embodiment.
Can also be reduced.

FIG. 6 shows an embodiment for simultaneously processing the tips of a plurality of optical fiber arrays arranged in an array.
This will be described with reference to FIG. Four optical fibers 27a, 27b,
Numerals 27c and 27d constitute an optical fiber array arranged at a fixed center interval by an alignment guide 28, and incident light for curing 14a, 1
4b, 14c, and 14d can be incident.
The end of the optical fiber array is lowered to the tank 29 filled with the photo-curable resin 2 by the optical fiber up / down operation 46, and then the end of the optical fiber array is placed in the photo-curable resin 2 with the bottom of the tank 29. The liquid is immersed while maintaining the constant interval h4. The curing light 14a, 14b, 14c, 14d of the photocurable resin 2 is guided to each core from the end faces of the four optical fibers that are not immersed, and the light emitted from the end faces of the respective optical fibers in the immersion liquid. Drain tank 2
The photocurable resin 2 in the space of the constant distance h4 from the bottom surface of the substrate 9 is cured. After a certain time has elapsed, the optical fiber up / down operation
When the optical fiber array is pulled up, a cured resin is formed at the end of each optical fiber, and the uncured resin adheres to the tip by an amount that balances the surface tension of the resin and gravity,
The uncured resin is cured by irradiating curing light to form a spherical lens. As described above, since the optical fiber array can be formed on a plurality of optical fibers at the same time, an optical fiber array with a lens can be easily formed.

[0018]

According to the present invention, a photocurable resin is adhered and cured to an optical fiber whose end face has only been cut, and then the uncured portion adhered by surface tension is cured.
It is possible to provide an optical fiber with a lens which is inexpensive, has a small radius of curvature of the lens, and has a high light coupling efficiency, and a method for manufacturing the same. Further, since the optical fiber array can be formed on a plurality of optical fibers at the same time, an optical fiber array with a lens can be easily formed.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a first embodiment of a method for manufacturing an optical fiber of the present invention.

FIG. 2 is an explanatory view of a second embodiment of the optical fiber manufacturing method of the present invention.

FIG. 3 is an explanatory diagram of optical coupling between an optical fiber with a lens according to the present invention and a semiconductor laser.

FIG. 4 is an explanatory view of a method for manufacturing another optical fiber with a lens according to the present invention.

FIG. 5 is an explanatory view of a tapered optical fiber with a lens according to the present invention.

FIG. 6 is an explanatory view of an embodiment of a method for manufacturing an optical fiber array according to the present invention.

FIG. 7 is an explanatory view of a conventional method for manufacturing an optical fiber with a lens.

FIG. 8 is an explanatory diagram of optical coupling between a conventional optical fiber with a lens and a semiconductor laser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 1a ... Core, 1b ... Cladding, 2 ... Photocurable resin, 3 ... Cured resin, 4 ... Uncured resin, 11 ... Curing incident light, 12 ... Outgoing light, 13 ... Curing light, 21: tank, 42: optical fiber raising operation.

Claims (6)

[Claims] 1. An optical fiber with a lens, wherein a lens made of a photocurable resin with an outermost diameter smaller than the outer diameter of the cladding of the optical fiber is attached to an end face of the optical fiber. 2. An optical fiber having a light guide portion having an outermost diameter smaller than the outer diameter of the cladding of the optical fiber on the end face of the optical fiber, and a lens attached to the end face of the light guide portion. Optical fiber. 3. An optical fiber with a lens according to claim 2, wherein said light guide section and said lens are formed of a photocurable resin. 4. An optical fiber array with a lens, wherein a plurality of the optical fibers according to claim 1, 2 or 3 are arranged. 5. A method for manufacturing an optical fiber with a lens, wherein an end of the optical fiber is immersed in a tank filled with a photocurable resin while maintaining a constant distance from the bottom of the tank, and the optical fiber is immersed in the tank. The light-curing light of the photocurable resin is used to cure the photocurable resin on the end face of the optical fiber in the immersion liquid, and after the optical fiber is pulled up, the uncured resin adhered to the end of the cured portion. Is cured with light for curing to form a lens. 6. A method of manufacturing an optical fiber with a lens, wherein light is guided through the optical fiber while keeping an end of the optical fiber at a constant distance from a liquid surface of the tank on a tank filled with a photocurable resin. By the curing light of the photocurable resin,
After curing the photocurable resin at a position corresponding to the optical fiber end face, and after almost contacting the optical fiber to the cured portion,
The contact surface is hardened and connected, and after the optical fiber is pulled up, the uncured resin attached to the end of the hardened portion is hardened with hardening light to form a lens. Method.